silverstream pipeline replacement project

Silverstream Pipeline Replacement Project Assessment of Effects on the Environment

23 August 2021

GHD Limited

Grant Thornton House, Level 1, 215 Lambton Quay

Wellington, Wellington 6011, New Zealand

T +64 4 495 5800 | F +64 4 472 0833 | http://www.ghd.com

Last saved date 23 August 2021

File name https://projects.ghd.com/oc/NewZealand3/silverstreampipebrid/Delivery/Documents/Consenting/Silverstream AEE .docx

Author Shannon Watson

Project manager Steven Kelliher

Client name Wellington Water Ltd

Project name WWL - Silverstream Pipe Bridge

Document title Silverstream Pipeline Replacement Project | Assessment of Effects on the Environment

Revision version Rev [00]

Project number 5137713

Document status

Revision Author Reviewer Approved for issue

Name Signature Name Signature Date

00 Shannon Watson Helen Anderson

Clive Welling

23/8/2021

© GHD 2021

This document is and shall remain the property of GHD. The document may only be used for the purpose for which it was commissioned and in accordance with the Terms of Engagement for the commission. Unauthorised use of this document in any form whatsoever is prohibited.

Silverstream Pipeline Replacement Project i

Limitations GHD prepared this document for the benefit of Wellington Water Limited (the Client), subject to the terms of the Professional Services Contract between the Client and GHD and for the purpose agreed between GHD and Wellington Water Limited as set out in Section 1.1 of this report. GHD accepts no liability or responsibility whatsoever for, or in respect of, any use of, or reliance upon, this report by any third party. This disclaimer shall apply notwithstanding that this document may be made available to other persons for an application for permission or approval or to fulfil a legal requirement.

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Contents

Limitations i

Glossary of abbreviations and defined terms vi Abbreviations vi Defined Terms viii

1 Introduction 1 1.1 Purpose of this report 1 1.2 The Applicant 1 1.3 The Project 1 1.4 Resource consents sought (“the Application”) 4 1.5 Structure of the Application and supporting documents 4 1.6 Structure of this AEE 4

2 Background and strategic context for the Project 6 2.1 Overview 6 2.2 Project objectives 6 2.3 The need for the Project 6 2.4 Strategic context 12 2.5 Design requirements 14 2.6 Consenting strategy – Project sections 16

3 Description of the existing environment 19 3.1 Introduction 19 3.2 General site location and description 19 3.3 Cultural 23 3.4 Landform 24 3.5 Water 27 3.6 Ecology 31 3.7 Built environment 36

4 Project description 40 4.1 Introduction 40 4.2 Pipeline 40 4.3 Pipe bridge 41 4.4 Works in rivers and streams 45 4.5 Earthworks and vegetation removal 45 4.6 Network utilities 46

5 Construction Methodology 47 5.1 Introduction 47 5.2 Development of the construction methodology 47 5.3 Indicative construction programme 48 5.4 General philosophy 48

Silverstream Pipeline Replacement Project iii

5.5 Enabling works 48 5.6 Main construction works 49 5.7 General construction aspects 52

6 Statutory context 55 6.1 Introduction 55 6.2 Resource Management Act 55 6.3 Plans and policy documents 58 6.4 Regional Policy Statement for the Wellington Region 61 6.5 Proposed Natural Resources Plan 61 6.6 Operative Regional Plans 61 6.7 City of Lower Hutt District Plan 62 6.8 Upper Hutt City Council District Plan 62 6.9 Activities requiring resource consent 62 6.10 Existing designations 71 6.11 Statutory acknowledgements 71 6.12 Other legislative matters 72 6.13 Activities considered to be otherwise consented 73

7 Consideration of Alternatives 74 7.1 Introduction 74 7.2 Project history and previous reports 74 7.3 Options Identification 75 7.4 Evaluation criteria and weightings 76 7.5 Option Shortlisting 78 7.6 Multi Criteria Analysis Process 79 7.7 Alternative bridge construction methodologies 83 7.8 Conclusion 83

8 Engagement and consultation 84 8.1 Introduction 84 8.2 Engagement approach 84 8.3 Public engagement 87 8.4 Post-lodgement engagement 87

9 Assessment of effects on the environment 88 9.1 Introduction and summary of effects on the environment 88 9.2 Construction effects 88 9.3 Ecology 92 9.4 Contaminated land 102 9.5 Landscape, natural character and visual effects 103 9.6 Dewatering 109 9.7 Natural hazards and geotechnical risk 112 9.8 Cultural values 114 9.9 Social and recreation impact 115 9.10 Network utilities 117

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9.11 Archaeology and heritage 118

10 Measures to manage effects on the environment 119 10.1 Introduction 119

11 Statutory assessment 123 11.1 Introduction 123 11.2 Assessment of relevant objectives and policies of planning documents 123 11.3 Other matters 142 11.4 Section 105 assessment 147 11.5 Section 107 assessment 149 11.6 Part 2 analysis 149

12 Summary 154

Table index

Table 1 Abbreviations used in this AEE vi Table 2 Defined Terms viii Table 3 Structure of the application 4 Table 4 Structure of the AEE 5 Table 5 Wellington Water Strategic Service Goals 13 Table 6 Limit State Definitions 15 Table 7 Plan Zones, overlays and notations 21 Table 8 Indicative construction movements 53 Table 9 Section 104 requirements 57 Table 10 PNRP consents sought - Construction 63 Table 11 RFP consents sought - Construction 65 Table 12 Land use consents sought from HCC - Construction 67 Table 13 Land use consents required from UHCC - Construction 68 Table 14 Existing consents 73 Table 15 Initial options 75 Table 16 Additional options 76 Table 17 Scoring range and descriptions 77 Table 18 Outcome of sensitivity testing 78 Table 19 Shortlisted options 78 Table 20 Assessment criteria 80 Table 21 Summary of Ecological Values assigned to affected habitats (as per EIANZ 2018) 92 Table 22 Summary of Ecological Values assigned to affected fauna species (as per EIANZ 2018) 92 Table 23 Magnitude of effect 93 Table 24 Matrix for overall level of effect 93 Table 25 Identified landscape effects 106 Table 26 Instrumentation monitoring frequency 111 Table 27 Trigger levels for settlement monitoring during construction 111 Table 28 Management plans to submit to Council’s 120 Table 29 Regional Policy Statement objectives and policies assessment 126 Table 30 Regional Freshwater Plan objectives and policies assessment 128

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Table 31 HCC DP objectives and policies assessment 132 Table 32 UHCC DP objectives and policies assessment 134 Table 33 Proposed Natural Resource Plan objectives and policies assessment 137

Figure index

Figure 1 Existing Kaitoke Main location 3 Figure 2 Project Overview 3 Figure 3 Expected water supply restoration times following a significant hazard event

(Silverstream site location shown in red) 10 Figure 4 Council Jurisdictional Boundaries 20 Figure 5 Plan Zones, Overlays and Notations 20 Figure 6 Flooding overlays from the UHCC DP and HCC DP 21 Figure 7 Designations for HCC and UHCC in the vicinity of works 23 Figure 8 Known locations of the Wellington Fault 26 Figure 9 Location of bores within 500 m of Project area (GWRC GIS portal) 31 Figure 10 Terrestrial community types within the Project area (from Appendix F) 32 Figure 11 Location of nearby archaeological sites 38 Figure 12 Elevation of the Silverstream Pipe Bridge 42 Figure 13 Evaluation criteria and sub criteria 77 Figure 14 Option 14 81 Figure 15 Network arch bridge preliminary design concept 82

Appendices

Appendix A Detailed Design Report Appendix B Figures Appendix C Detailed Site Investigation Appendix D Assessment of Dewatering Effects Appendix E Hydraulic Assessment Appendix F Ecological Impact Assessment Appendix G Assessment of Natural Character, Landscape and Visual Effects Appendix H Archaeological Assessment Appendix I General layout and preliminary design plans Appendix J Assessment of relevant rules in regional and district plans Appendix K Engagement Register Appendix L Iwi engagement correspondence Appendix M Proposed consent conditions Appendix N Relevant objectives and policies of national, regional and district planning documents

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Glossary of abbreviations and defined terms Abbreviations

Table 1 below sets out the technical abbreviations.

Table 1 Abbreviations used in this AEE

Abbreviation/Acronym

Term

AEE Assessment of environmental effects

AEP Annual exceedance probability

ARI Average return interval

BPO Best practicable option

CEMP Construction Environmental Management Plan

CLMG Contaminated Land Management Guidelines

CLMP Contaminated Land Management Plan

CNVMP Construction Noise and Vibration Management Plan

CoPTTM Code of Practice for Temporary Traffic Management

CPT Cone penetrometer test

dB Decibel

HCC DP City of Lower Hutt District Plan

DOC Department of Conservation

DSI Detailed site investigation

ESC Erosion and sediment control

ESCP Erosion and Sediment Control Plan

GIS Geographical information system

GWRC Greater Wellington Regional Council

Ha Hectares

HAIL Hazardous Activities and Industries List

HCC Hutt City Council

HNZPT Heritage New Zealand Pouhere Taonga

km Kilometres

L/s Litres per second

m Metres

m2 Square metres

m3 Cubic metres

MCA Multi criteria analysis

MfE Ministry for the Environment

MSE Mechanically stabilised earth

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Abbreviation/Acronym

Term

NES National Environmental Standard

NESFW Resource Management (National Environmental Standards for Freshwater) Regulations 2020

NES Soil Resource Management (National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health) Regulations 2011

NPS National Policy Statement

NPSFM National Policy Statement for Freshwater Management 2020

NZS 6803 New Zealand Standard NZS 6803:1999 “Acoustics – Construction Noise”

OD Outer diameter

PNRP Proposed Natural Resources Plan for the Wellington Region (Appeals version)

PSI Preliminary site investigation

RFP Operative Regional Freshwater Plan for the Wellington Region

The River Te Awa Kairangi/Hutt River

RMA Resource Management Act 1991

RPDL Regional Plan for Discharges to Land for the Wellington Region

RPS Regional Policy Statement for the Wellington Region

SH2 State Highway 2

UHCC DP Upper Hutt City Council District Plan

Waka Kotahi Waka Kotahi NZ Transport Agency

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Defined Terms

Table 2 below sets out the defined terms (and some acronyms above apply)

Table 2 Defined Terms

Term Definition

Active channel Area of the river bed covered by flowing water at any particular time

Amenity values Defined in section 2(1) of the RMA as “those natural or physical qualities and characteristics of an area that contribute to people’s appreciation of its pleasantness, aesthetic coherence, and cultural and recreational attributes.”

Annual exceedance probability

The probability of exceeding a given threshold within a period of one year. It can be applied to any type of risk.

Archaeological site Defined in section 6 of the Heritage New Zealand Pouhere Taonga Act 2014 as “Means, subject to section 42(3), (a) any place in New Zealand, including any building or structure (or part of a building or structure), that (i) was associated with human activity that occurred before 1900 or is the site of the wreck of any vessel where the wreck occurred before 1900; and (ii) provides or may provide, through investigation by archaeological methods, evidence relating to the history of New Zealand; and (b) includes a site for which a declaration is made under section 43(1).”

Average Recurrence Interval

The average time period between rainfall or flow events that exceed a given magnitude.

Background concentrations Defined in the NES Soil as “naturally occurring ambient concentrations of the element (contaminant) in soil in the area local to the land”.

Best practicable option Defined in section 2(1) of the RMA, as “in relation to a discharge of a contaminant or an emission of noise, means the best method for preventing or minimising the adverse effects on the environment having regard, among other things, to – (a) the nature of the discharge or emission and the sensitivity of the receiving environment to adverse effects; and (b) the financial implications, and the effects on the environment, of that option when compared with other options; and (c) the current state of technical knowledge and the likelihood that the option can be successfully applied.”

Construction works Activities undertaken to construct the Project.

Contaminant Defined in section 2(1) of the RMA, as “any substance (including gases, odorous compounds, liquids, solids, and micro-organisms) or energy (excluding noise) or heat, that either by itself or in combination with the same, similar, or other substances, energy, or heat – (a) when discharged into water, changes or is likely to change the physical, chemical, or biological condition of water; or (b) when discharged onto or into land or into air, changes or is likely to change the physical, chemical or biological condition of the land or air onto or into which it is discharged.”

Contaminated land Defined in section 2(1) of the RMA, as “land that has a hazardous substance in or on it that – (a) has significant adverse effects on the environment; or (b) is reasonably likely to have significant adverse effects on the environment.”

Cumec A cumec measures water flow. 1 cumec (1 cubic metre per second) equals 1 cubic metre passing a given point every second.

dB LAeq(24h) Sound pressure level average, A-weighted, sound pressure level over the measurement period of 24 hours.

Designation Defined in section 166 of the RMA, as “a provision made in a district plan to give effect to a requirement made by a requiring authority under section 168 or section 168A or clause 4 of Schedule 1 of the RMA.”

Design Channel As defined by GWRC Hutt River Flood Management Plan, dated October 2001.

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Term Definition

Defined as: The optimum river channel width and alignment to carry floods. A theoretically developed natural and sustainable channel has been refined to match the existing form of the Hutt River as far as reasonable. It is the channel that will be maintained for the Hutt River in order to lessen the potential for berm areas, stopbanks and developed urban areas to be damaged in floods.

Discharge Defined in section 2(1) of the RMA, as including emitting, depositing, and allowing to escape.

Erosion control Methods to prevent or minimise the erosion of soil, in order to minimise the adverse effects that land disturbing activities may have on a receiving environment.

Fish passage The movement of fish between the sea and any river, including up-stream or downstream in that river.

Groundwater Natural water contained within soil and rock formations below the surface of the ground.

Heavy vehicle A motor vehicle having a gross laden weight exceeding 3500 kg.

Kaitiakitanga Guardianship.

Mauri The essential quality and vitality of a being or entity.

Ngā Taonga Nui a Kiwa Those large freshwater and coastal entities from which mana whenua derive cultural and spiritual identity, their status as mana whenua and the associated responsibilities that come with that including those of kaitiaki. These places are the larger rivers and harbours that have a long history of multiple and complex resource use associated with large populations. Ngā Taonga Nui a Kiwa emphasises the importance of mana whenua relationships with rivers, lakes, harbours and estuaries.

Piece of land The portion of a site, or property, on which hazardous activities are being, have been or are more likely than not to have been undertaken. The NES Soil applies to the piece of land occupied by the HAIL activity. A piece of land may extend beyond the property parcel.

Pier Vertical support structure for a bridge.

The Project The Silverstream Pipeline Replacement Project.

Project works All proposed activities associated with the Project.

Sediment control Measures to prevent or minimise the discharge of sediment that has been eroded.

State highway Means a road, whether or not constructed or vested in the Crown, that is declared to be a State highway under section 11 of the National Roads Act 1953, section 60 of the Government Roading Powers Act 1989 (formerly known as the Transit New Zealand Act 1989), or under section 103 of the LTMA.

Taonga A treasured/highly prized object or natural resource.

The Application This application for resource consent

True Right Bank The right bank of a river when facing downstream. In the case of this Project it is the western bank, i.e. the side that includes State Highway 2.

True Left Bank The left bank of a river when facing downstream. In the case of this Project it is the eastern bank, i.e. the side that includes Eastern Hutt Road.

Silverstream Pipeline Replacement Project 1

1 Introduction The existing ‘Te Mārua to Karori’ drinking water pipeline (known as the Kaitoke Main) runs from the Te Mārua water treatment plant to the Karori pump station. It supplies 100% of Porirua City’s and 40% of Wellington City’s daily potable water needs.

In 2015, the Kaitoke Main, that crosses Te Awa Kairangi/Hutt River via the Silverstream road bridge on Fergusson Drive was identified as significantly corroded. In addition, the pipe crosses the Wellington Fault line and damage as a result of an earthquake would likely interrupt water supply to Porirua and Wellington City for a significant period of time.

The Silverstream Pipeline Replacement Project (the Project) proposes to relocate the section of water pipe that is attached to the Silverstream road bridge and along State Highway 2 (SH 2) by constructing a purpose-built bridge over Te Awa Kairangi/Hutt River approximately 330 metres downstream of the road bridge, and a new section of underground pipeline in Manor Park Golf Course to improve resilience in earthquake and flood events. The bridge will be dual use, able to carry a new water pipe and additional smaller three waters infrastructure in future and will also provide access for pedestrians and cyclists between Silverstream and Manor Park.

1.1 Purpose of this report

The purpose of this report is to present the required information in support of resource consent applications for the construction, operation and maintenance of the new pipe bridge and replacement section of the Te Marua to Karori main pipeline (Kaitoke Main) at Silverstream (the Project). Resource consent is required from Hutt City Council, Upper Hutt City Council and Greater Wellington Regional Council respectively.

1.2 The Applicant

1.2.1 Wellington Water Limited

Wellington Water Limited is the Applicant for the Silverstream Pipeline Replacement Project.

Greater Wellington Regional Council (GWRC) owns the assets involved in the supply of bulk water, including four water treatment plants, 15 pumping stations and just over 180 kilometres of large-diameter pipelines. Wellington Water Limited’s role is to manage the treatment and supply of water to the Wellington Region. Since 19 September 2014, Wellington Water has managed the bulk water supply function of GWRC under a service delivery contract.

Wellington Water Limited will be responsible for the construction and operation of the pipeline and compliance with consent conditions.

1.3 The Project

The purpose of the Project is to replace an aging section of the Kaitoke Main at Silverstream to improve the resilience of the bulk water supply network. At present, the Silverstream section of the Kaitoke Main is nearing the end of its economic and asset life. Testing and inspection of the pipe shows that the integrity of the pipe is


deteriorating due to corrosion. Completion of the Project will ensure that Wellington Water are proactively protecting the supply of water to Wellington, Porirua and Stokes Valley1.

The Kaitoke Main is essential to the overall integrity and resilience of the region’s water supply. It would be difficult, if not impossible, to meet the region’s normal water demand if the pipeline failed. In that event, all water would need to be supplied via the other main regional sources at Waterloo and Wainuiomata and the network would be unable to meet expected demand for water.

The economic losses resulting from the failure of this section of the pipeline are significant and will escalate the longer the water supply disruption lasts. When looking at the economic impact to Porirua alone, the loss of water would directly impact normal business operation and significantly reduce the annual GDP for Porirua.

Restoring the water supply to Porirua is estimated to take approximately 40 days after a major earthquake and much longer to restore water supply to the areas of Wellington City serviced by the Kaitoke Main. Potential costs incurred over this time include:

– Disruption for customers who rely on the provision of water to run their businesses.

– Costs incurred providing the basic water needs of 20 litres of water per-person per-day, for all of Porirua and the western and northern areas of Wellington and the economic and operational costs associated with people being limited to 20 litres of water per-person per-day.

– Emergency repairs and the consequential disruption of traffic along high usage areas of the road network adjacent to the pipeline.

To ensure rapid recovery following a major earthquake, core infrastructure needs to be as resilient as possible and have the capability to be returned to service in the shortest practicable amount of time.

The construction of a more durable pipeline in this location is expected to significantly reduce the time that would be required to restore the water supply to Porirua City and a further reduction to the time it would take to restore water to Wellington City and beyond.

WWL is proposing to replace the section of the Kaitoke Main that runs between the existing Kingsley valve chamber in Fergusson Drive, Silverstream and the existing branch main immediately north of the stream running through Keith George Memorial Park located on the western side of SH2 (shown in Figure 1 below, and Appendix B).

The wider Project also involves the replacement of an associated pipeline (the Kingsley pipeline) which supplies all water to Stokes Valley (also shown in Figure 1). The Kingsley pipeline component (refer Figure 2 and Appendix B – Section 1 & 2) is being consented separately to the proposed new pipe bridge across the Te Awa Kairangi/Hutt River. The wider Project includes:

– Replacement of this section of the Kaitoke Main with a new pipeline along Fergusson Drive, which will cross Te Awa Kairangi/Hutt River via a new pipe bridge (refer Figure 2 – Section 3) to join the existing trunk main located in the rail corridor approximately 200 m south of Keith George Memorial Park Stream (Section 4).

– Provision of a new water supply main connecting the Kingsley Pump Station to the new trunk main along Eastern Hutt Road (refer Figure 2 – Section 2). The Kingsley pipeline provides Stokes Valley with its water and its upgrade will ensure continuity of service for Stokes Valley.

– The preliminary design and bridge design plans are also contained in Appendix I.

1 Stokes Valley is supplied by the Kingsley pipeline, the replacement of this pipeline is part of the broader programme of replacement works at Silverstream (refer section 2.6 of this report for further detail.


Figure 1 Existing Kaitoke Main location

Figure 2 Project Overview


1.4 Resource consents sought (“the Application”)

1.4.1 Regional resource consents

Various resource consents are required for the construction of the Project as detailed in section 6: Statutory context, of this application. In summary, the following resource consents are required pursuant to the GWRC Proposed Natural Resources Plan (PNRP) Appeals Version (as at 21 August 2021) and the relevant operative regional plans:

– Land use consents for earthworks in accordance with section 9(2) of the RMA;

– Land use consents for works in the bed of a river in accordance with section 13 of the RMA;

– Water permits for temporary diversion of groundwater and temporary and permanent diversion of surface water in accordance with section 14 of the RMA; and

– Discharge permits for discharges of sediment to land and water in accordance with section 15 of the RMA.

1.4.2 District land use consents

Resource consent is sought from HCC to disturb the soil of contaminated land during construction as a controlled activity under regulation 9(1) of the NES Soil. This consent is pursuant to section 9(1) of the RMA, for an activity that is not allowed by a National Environmental Standard without a resource consent.

Land use consents (section 9(3) of the RMA) from UHCC and HCC are also sought for the following activities:

– Bulk earthworks and land disturbance works;

– Construction of the pipe bridge across Te Awa Kairangi/Hutt River;

– Construction of new underground and above ground sections of pipeline; and

– Ground improvement works.

1.5 Structure of the Application and supporting documents

This application and associated technical reports, design drawings and supporting information, contains the information required by the RMA. The structure of the application is set out in Table 3 below.

Table 3 Structure of the application

Name Contents

Resource consent application forms Forms for resource consents (Form 9). Schedule of land directly affected by the resource consents. Proposed resource consent conditions.

Assessment of Effects on the Environment AEE (this report).

Supporting Technical and Assessment Reports Technical reports detailing the design requirements and assessing the effects of the construction and operation of the Project.

Drawing Set Indicative design drawings for all aspects of the Project including pipelines, pavement/paths, location and design of pipe bridge and other structures. Drawings supporting the technical assessments.

1.6 Structure of this AEE

In accordance with the requirements of the RMA (and particularly Schedule 4), this AEE provides the following information and it is structured as set out in Table 4 below.


Table 4 Structure of the AEE

Section Name Contents

1 Introduction An introduction to the Application, Applicants and Project, including summary of required approvals and structure of the AEE and application

2 Background and strategic context for the Project

Sets out the background and strategic context and need for the Project and the Project objectives

3 Description of the existing environment Description of the existing environment

4 Description of the Project Description of the Project

5 Construction of the Project An outline of the indicative method to construct the Project

6 Statutory context Identification of the legal framework that applies to the Application, and identification of the required approvals

7 Consideration of alternatives The methodology by which alternatives to the various Project elements have been considered

8 Consultation and engagement An outline of the engagement that has occurred during preparation of the Application, feedback received and responses to issues raised

9 Assessment of effects on the environment Outline of the methodology and assessment of the actual and potential effects on the environment, including consideration of measures proposed to avoid, remedy or mitigate effects

10 Management of effects on the environment Proposed measures to manage the identified effects, including a management plan framework

11 Statutory assessment An assessment of the Project against the matters set out in applicable provisions of the RMA. An assessment of the project against the relevant provisions of relevant national, regional and local statutory and non-statutory documents.

12 Summary Summary

Appendix M Proposed Conditions of Consent Proposed District and Regional consent conditions


2 Background and strategic context for the Project

2.1 Overview

This section provides background information about the Project, the strategic context with regard to project objectives and need for the Project and the consenting strategy that has been adopted.

2.2 Project objectives

The overall objective of the Project is to improve the resilience of the bulk water supply network, by replacing the Kaitoke Main at Silverstream and an associated pipeline (the Kingsley pipeline) which supplies water to Stokes Valley. Completion of the Project will enable the on-going supply of water to Wellington, Porirua and Stokes Valley.

The following objectives have informed the Project design and implementation:

Function

The new water supply infrastructure can continue to supply 100% water to Porirua, 40% water to Wellington and all of Stokes Valley (the dependent population) from 2021, and have an asset life meeting or exceeding 100 years.

Resilience and repairability

The new water supply infrastructure is likely to remain in service after 1 in 2,500 year earthquake event (6.25 magnitude in Upper Hutt, Wellington Fault) and a 1 in 2,500 year flood event.

Where the new water supply infrastructure fails, the supply can be permanently or temporarily reinstated within 30 days (using equipment likely to be available in close proximity) to continue to deliver water to the dependent population.

Flood protection

Any new bridge structure across the Hutt River provides for a 2,800 cumec flood (which is larger than a 1 in 2,500 year return period flood event) to pass.

2.3 The need for the Project

2.3.1 Problem identification

A number of strategic investigations, scoping studies, scheme assessment and business case processes have been undertaken between 2015 and 2019 which identified the following key issues, which are sought to be addressed through the Project.

Key drivers for the replacement of the identified section of the current Kaitoke Main pipeline relate to addressing the following risks for the existing water pipeline(s):

– The condition of the existing pipeline is compromised, exacerbating maintenance requirements and posing a risk of failure or rupture.


– The existing pipeline is built across the Wellington Fault and is highly vulnerable to damage or failure in a major earthquake event.

– The existing pipeline is attached to the deck of the Silverstream road bridge and is at risk of failure or damage in any flood event greater than a 1 in 40 year event.

– The existing pipeline is located under SH 2 and access and repairs would be time consuming and highly disruptive to traffic flows on SH 2.

These key drivers are outlined in further detail below.

2.3.1.1 Condition of the existing pipeline

A study of the condition of the existing pipeline undertaken by MWH (now Stantec) in 20152 found that the existing pipeline attached to the Silverstream road bridge, which connects SH 2 and Fergusson Drive, is affected by pit corrosion that will result in an increasing prevalence of pinhole leaks which will exacerbate maintenance requirements and potentially lead to failure or rupture. The condition assessment identified numerous coating defects and sections of pipe with no cathodic protection and noted that the pipeline alongside the SH 2 corridor south of Silverstream road bridge is also affected by stray electrical currents, understood to be originating from the electrical rail system and a railway transformer adjacent to SH 2, which are likely to be causing accelerated corrosion of the pipeline in this area. The MWH report references a study undertaken by MPT Solutions on the condition of the pipeline in 2007 which predicted the remaining pipeline asset life in some areas to be as low as 5 and a half years.

The pipeline attached to the Silverstream road bridge is affected by atmospheric corrosion which, over time, will result in an increasing prevalence of pinhole leaks. While pinhole leaks do not significantly reduce the performance of the pipeline by themselves, they are an indication that the pipeline is severely affected by corrosion. The reduced wall thickness (due to corrosion) places the pipeline at risk of catastrophic failure. Since 2006 WWL have been renewing the tie-bolts, repairing the ring girders, reworking the support angles and bracing, sandblasting and painting sections of the existing pipeline at each bridge pier. The last significant repairs were carried out in 2012. At the time of sandblasting for painting, contractors experienced water weeping through the walls of the pipeline which could not be spot welded because of the pressure in the pipe. The main had to be shut down and drained, with welding repairs carried out, over a period from 28th Feb to March 22nd, 2012. However, the leaks recorded were expected to worsen over the following five years in line with the 2007 MPT Solutions investigations.

2.3.1.2 Seismic resilience

The Kaitoke Main crosses the Wellington Fault adjacent to and within Te Awa Kairangi/Hutt River. It is therefore within a ‘high ground acceleration zone’ and where significant displacement each side of the Fault is expected, and where the pipe is likely to break (or fail) in a significant seismic event. The pipeline crosses the Wellington Fault adjacent to the western abutment of Silverstream road bridge. The pipeline, as currently constructed, is not considered to be resilient in the event of major seismic movement.

Investigations have determined the Silverstream road bridge is also highly vulnerable to damage in a major earthquake, and the bridge would be difficult to reinstate following rupture or displacement of the Wellington Fault. The MWH report notes seismic strengthening was carried out on the bridge in 2012 to bring it to current standards (at 2015) however the proximity to the Wellington Fault still remains a significant risk to the bridge.

2 Silverstream Bridge Pipeline Condition Assessment and Realignment Options Feasibility Study, MWH, July 2015


A report produced by UHCC in 20003 regarding strengthening of the Silverstream road bridge noted the bridge was constructed in 1937/38 and was in reasonable condition for its age however ongoing maintenance was required to prolong its design life. A report from GHD prepared for UHCC shows that the bridge was strengthened in the longitudinal direction for seismic load in 20074. The strengthening works included strengthening of bridge diaphragms and diagonally post-tensioning or anchoring of the eastern abutment and first eastern pier to the ground. However, due to site and cost constraints, the bridge was not strengthened in the transverse direction as it was found satisfactory for smaller transverse seismic events (remain usable after a 1 in 450 year earthquake event).

The bridge has not been strengthened to resist a “Wellington Fault event” due to a low benefit cost ratio for achieving such additional capacity given the limited remaining ‘asset life’ left in the bridge.

As a result, Silverstream road bridge is highly vulnerable to damage from any major movement of the Wellington Fault.

2.3.1.3 Flood hazard risk

The Wellington Regional Council’s Hutt River Floodplain Management Plan 2001 (HRFMP) describes that the existing Silverstream road bridge only has a five-year flood capacity with an allowance for passing debris. Without allowance for debris, the bridge is currently designed to pass a 1 in 40 year flood event. The pipeline is therefore at risk of being submerged and of debris strikes in even moderate flooding events.

Additionally, as the existing pipeline is located below the haunches of the bridge beams the pipeline has the potential to raise upstream flood levels during a flood event.

2.3.1.4 Access and maintenance

The topography of the area creates a pinch point between the Hayward Hills and the Hutt River, and includes the Wellington Fault between these features. A Wellington Lifelines Group/WREMO Lifelines Study identifies the section of SH 2 along the Haywards Hill as a location where a significant earthquake could cause a full road closure or slope failure5.

The MWH report6 describes that downstream of the Silverstream road bridge the pipe is buried under SH 2 for a distance of approximately 1500 m, to the bottom of Haywards Hill. When SH 2 was widened in the nineties, approximately 2 m of fill was built up over the pipeline. Repairs to the section of pipeline within SH 2 would be time consuming (days rather than hours) and highly disruptive to traffic flows on SH 2.

2.3.2 Consequences if problems not addressed

A major failure or disruption in one part of the water network is likely to significantly affect other parts of the network. Bulk water supply to reticulated areas of Porirua City and the northern and western areas of Wellington City is usually supplied from the Te Mārua Water Treatment Plant (via Kaitoke Main). Any disruption to the Kaitoke Main would impact directly on the supply of all water to Porirua and northern and western areas of Wellington. The Kaitoke Main is essential to the overall integrity and resilience of the region’s water supply. It would be difficult, if not impossible, to meet the region’s normal demand if the pipeline failed. In that event, all water would need to be supplied via the other main regional sources at Waterloo and Wainuiomata and the network would be unable to meet expected demand for water. With no viable network alternative, WWL customers will need to wait until repairs are carried out before drinking water can be restored. This represents a

3 Strategic Plan Review - Silverstream Bridge Strengthening, UHCC, 2000 4 Silverstream Bridge Seismic Strengthening Final Report, GHD Limited, July 2007. 5 WeLG / WREMO ‘Transport Access’ initial project report – March 2013 6 Silverstream Bridge Pipeline Condition Assessment and Realignment Options Feasibility Study, MWH, July 2015


serious risk to WWL customers’ safety, and to the ability of the region to recover from a significant natural hazard event.

Figure 3 demonstrates how long populations reliant on the WWL water supply network are expected to be without water following a significant natural hazard event. Depending on the damage to the bulk water network, Porirua could be without water supplied from the bulk water network for over 40 days after a significant event, and areas of northern and western Wellington could be without water for much longer (over 70 days)7. This would result in significant disruption costs, represents a serious risk to human and animal welfare, and would significantly impact the region’s ability to recover from a significant event.

The economic losses resulting from the failure of this section of the pipeline are significant and will escalate the longer the water supply disruption lasts. Potential costs incurred over this time include:

– Disruption for customers who rely on the provision of water to run their businesses;

– Costs incurred providing the basic water needs of 20 litres of water per-person per-day, for all of Porirua and the western and northern and western areas of Wellington;

– The economic and operational costs associated with people being limited to 20 litres of water per-person per-day; and

– Emergency repairs and the consequential disruption of traffic along SH 2 and Fergusson Drive; both high usage areas of the road transport network

Loss of water supply to such a large population following either operational failure of the pipeline or a significant event will have serious implications for businesses in Porirua City and northern and western areas of Wellington City, and the health of the population living in these areas. In addition, this will place significant pressure on resources (both local labour and available roading infrastructure) and repairs will be challenging to implement to the pipeline along SH 2.

When looking at the economic impact to Porirua alone, the loss of water would directly impact normal business operation and significantly reduce the annual GDP for Porirua. The data shows an annual GDP for Porirua of about $1.86bn8 or about $5 million per day. Under a mains break scenario, GDP will be affected for approximately 40 days which is in the order of $200M in GDP for Porirua. These losses are a result of latent insurance costs and economic losses to local business as a result of reduced output of businesses that rely on a stable water supply including food preparation establishments such as cafes, restaurants and food manufacturers, and large business customers such as Whittaker’s Chocolates.

As transport plays a key role in enabling economic growth and productivity, the location of the pipeline in SH 2 would also cause significant disruption that has direct and other flow-on impacts on the economy. Using the NZ Transport Agency’s economic evaluation manual9, there would also be additional economic losses resulting from delays to commuters travelling to Wellington from Upper Hutt, including longer travel times, increased congestion and bottleneck delays, increased fuel cost and reduced working hours for commuters adapting to the changing travel conditions.

7 Water Supply Resilience Recommended Programme: Towards 80-30-80, Wellington Water, 2017 8 https://ecoprofile.infometrics.co.nz/porirua%2bcity/QuarterlyEconomicMonitor/Gdp 9 https://www.nzta.govt.nz/resources/economic-evaluation-manual


Figure 3 Expected water supply restoration times following a significant hazard event (Silverstream site location shown in red)

2.3.3 Project benefits

The Project, to improve the resilience of the Kaitoke Main, provides the following benefits:

– Reduces the time taken to restore supply to customers in Porirua and affected parts of Wellington after a significant event.

– Provides increased security of supply to customers in Porirua, northern and western Wellington parts of Hutt City, and Stokes Valley10.

– Reduction in emergency water supply costs.

– Reduction in community and business disruption.

– Reduction in the risk of emergency repairs which could take a considerable time to carry out.

– Maintenance of public health and sanitation, which would be severely compromised by a prolonged outage.

– Avoidance of disruption to a major transport route (SH 2) to effect repairs.

Further detail regarding Project benefits is provided below.

10 Security of supply of water to Stokes Valley is provided through the Kingsley pipeline section


2.3.3.1 Reduction in expected time to restore water supply

As reported in the October 2016 Three Waters Decision Making Committee paper11, after an earthquake event, the construction of a resilient pipeline in this location is expected to provide around 23 days’ improvement in time to restore water supply via SH 58 to Porirua City and 21 – 23 days improvement in time to restore water to affected areas of Wellington City.

2.3.3.2 Reduced network utility costs

The location of the Project passes through an area of modified character within the Hutt River corridor, nested downstream of the existing rail and road bridges. Through ongoing work with GWRC’s Flood Protection Department (GWRC Flood Protection) which works with communities to manage flood risk from the region’s rivers and streams by managing waterways to keep them away from people rather than keeping people away from the waterways, the alignment selected mitigates costs associated with management of the river bed and banks, through locating the proposal as close as practicable to existing development to avoid creating a separate modified area requiring erosion control.

The proposed pipe bridge includes provision for a future second pipe or network utility to be constructed on the bridge in future. This offers benefits in the form of a reduction in future operational costs, as costs to manage the river corridor can be reduced if infrastructure can be co-located onto the new pipe bridge in the future.

2.3.3.3 Resources following a hazard event

Following a major earthquake event the Community Infrastructure Resilience (CIR) Strategy would be in effect, which sets a plan in place to provide water from resilient reservoirs and alternative water sources until the bulk water network is back online. The CIR plan was initiated to deliver on the short term goals of the Towards 80-30-80 strategy12 and requires significant temporary resource and personnel to provide the basic water needs of 20 litres of water per person per day. For Porirua and areas of the north and west of Wellington, this would require customers to collect water in bottles from tap stands at local distribution points after a major event until restoration of the network, which as noted above could be over 100 days in some areas.

If the resilience of the water supply from Te Mārua WTP through Silverstream can be strengthened, the resources to maintain this temporary supply can be distributed elsewhere and minimise traffic movements transporting water.

2.3.3.4 Active transport improvements

As part of the Project, there is an opportunity to incorporate a walking and cycling path as part of the design of the new pipe bridge, resulting in improved resilience (refer 2.3.3.5 below) and an effective solution to cross the river being achieved for the community. This would improve active transport connections by providing the opportunity to create a direct pedestrian and cycle connection between Silverstream and Manor Park.

The design of the new bridge approaches will provide dedicated active mode connections to existing and planned cycle routes in the area, including the planned active mode improvements through Manor Park Golf Course and the KiwiRail corridor to the north of the proposed bridge13. Provision of cyclist and pedestrian connections as part of the bridge design will address a missing link in the regions’ pedestrian and cycleway network.

11 3 Waters Decision Making Committee Paper: GWRC Silverstream Bridge Pipe Replacement – Current Status and Proposed Way Forward, WWL, 2016 12 Water Supply Resilience Recommended Programme - Towards 80-30-80. The goal of the 80-30-80 strategy is to provide 80% of customers, within 30 days of a reasonable seismic event, with 80% of their normal water needs 13 Waka Kotahi and Hutt City Council have approved funding for improved active mode connections, in the form of a three to four metre wide shared path to the north of the bridge location along the rail corridor towards Manor Park.


2.3.3.5 Transport network resilience

Emergency civil defence access has also been considered in the design of the pipe bridge. The proposed dual use pipeline and walking and cycling bridge would increase transport resilience in the area. While the pipe bridge will provide enough clearance for maintenance vehicles, depending on design, the bridge could include the ability for larger light vehicles to cross the bridge in a civil defence emergency and one-way light vehicle access could be used for civil defence purposes.

2.4 Strategic context

Wellington’s water supply network crosses multiple fault lines and many of the region’s customers are a long way from one of the region’s three main water sources that feed the network. As noted above, a significant seismic event will disrupt water supplied to the communities of Porirua, and northern and western areas of Wellington, for a long period of time.

2.4.1 Water Supply Resilience Strategic Case

With no viable network supply alternative to meet required demand for water, the community will need to rely on very limited emergency water supplies until repairs to the network can be made. To address the network’s vulnerability to natural disasters a Water Supply Resilience Strategic Case14 was developed and endorsed by all councils and sets the context for developing a strategy to improve the resilience of the water supply network founded on the principles of the Civil Defence and Emergency Management Act 2002 (CDEM Act). The CDEM Act requires councils to ensure they are able to continue to function to the fullest possible extent following a hazard event; although that may be at a reduced level.

2.4.2 Water Supply Resilience Recommended Programme: ‘Towards 80-30-80’

The reduction of time that water can be restored to customers after a major event is a long-term goal endorsed by GWRC and Wellington Water; this is to provide 80% of customers with 80% of their drinking water within 30 days of a reasonable seismic event (Towards 80 – 30 - 80). ‘Towards 80-30-80’ describes the key principles and recommended programme to address problems and reduce the risks of recovering from a significant earthquake event. At the time of preparation of the strategy, the Kaitoke Main replacement had already been allocated funding in the GWRC Long Term Plan 2015-202515 given it is a critical asset to the bulk water supply network, and subsequently the Project was in the feasibility and optioneering phases.

To ensure rapid economic recovery following a major earthquake, and to minimise the impact of an operational failure and repair, it is imperative that core infrastructure is as resilient as possible, and lifeline utilities such as the Kaitoke Main are able to continue to function to the fullest possible extent following a hazard event. The construction of a more resilient water supply network in this location is expected to directly provide around 21-23 days’ reduction to the 40 days’ that would be required to restore the water supply to Porirua City and a further reduction to the time it would take to restore water to Wellington City and beyond under the existing situation.

In summary, the replacement of the Kaitoke Main at Silverstream has been in planning well before the ‘Towards 80-30-80’ strategy was developed and is essential to the successful implementation of the programme.

14 “Legislative requirements” - Water Supply Resilience Strategic Case, Wellington Water, 2015 15 Long Term Plan 2015-2025 http://www.gw.govt.nz/long-term-plan-2015/

http://www.gw.govt.nz/long-term-plan-2015/


2.4.3 Wellington Lifelines Resilience Programme

Wellington Lifelines Group (WeLG) has developed a regional lifeline utility resilience programme16 developed from the plans, strategies and policies that exist from all of Wellington’s lifeline infrastructure providers. The programme identifies interdependencies between infrastructure projects and prioritises projects to reduce the national economic impact following a major earthquake event. WeLG has developed a Regional Lifelines Utility Resilience Programme which shortlists 25 priority infrastructure projects that will deliver maximum resilience benefits to Wellington. The programme lists the Kaitoke Main replacement at Silverstream in Phase One of the programme as a ‘must-do’ for the Wellington region.

Completing resilience infrastructure projects prioritised in the programme is a step forward in minimising the social and economic impact following a major earthquake.

2.4.4 Long Term Plan 2018 - 2028

The Kaitoke Main replacement at Silverstream is a major renewal project programmed for delivery in the GWRC 2018 - 28 Long Term Plan (LTP). This project aligns with both priority areas detailed in the GWRC’s LTP; water supply and regional resilience.

With regional resilience a priority area for GWRC, the strengthening of the bulk water network in this location is crucial to protecting the supply of water to Porirua and minimising the length of time before water can be restored to other areas of the region.

2.4.5 Wellington Water Service Goals

The replacement of the Kaitoke Main at Silverstream aligns with the following Wellington Water strategic service goals (Table 5 below).

Table 5 Wellington Water Strategic Service Goals

Objective Description

Primary

We provide reliable services to customers. Customers have access to reliable water and wastewater services.

The new water supply infrastructure can continue to supply 100% of Porirua and Stokes Valley’s water, and 40% of Wellington’s water (the dependent population) from 2021, and will have an expected service life meeting or exceeding 100 years.

Secondary

We provide three water networks that are resilient to shocks and stresses. We work to meet agreed levels of service to restore water services to customers.

16 Wellington Lifelines Project: Protecting Wellington's Economy Through Accelerated Infrastructure Investment Programme Business Case https://www.wremo.nz/assets/Uploads/Wellington-Lifelines-PBC-MAIN-Combined-20191009.pdf

https://www.wremo.nz/assets/Uploads/Wellington-Lifelines-PBC-MAIN-Combined-20191009.pdf


The new water supply infrastructure is designed to remain in service after a 1 in 2,500 year earthquake event (7.1 magnitude in Upper Hutt, Wellington fault) and 1 in 2,500 year flood event17.

Should the new water supply infrastructure fail, supply can be relatively quickly reinstated following the 80-30-80 strategy using equipment likely to be available in close proximity. This would require the pipeline to be reinstated into operation within days.

2.5 Design requirements

The design requirements for the Project are outlined in section 3 of the Detailed Design Report, attached as Appendix A and are summarised below.

2.5.1 Basis of Design

The Basis of Design is informed by the Project Design Brief (the Design Brief) for the Project issued by WWL in October 2015. The Design Brief specified that the Kaitoke Main is required to have an Importance Level of 4 (IL4) as defined by AS/NZS 1170 (Structural Design)18.

In addition, the Design Brief specified the following criteria:

– The pipeline shall remain operational as far as practicable following a major earthquake (annual probability of 1 in 1,000 years);

– The pipeline shall be able to be repaired using materials, plant, and resources reasonably expected to be available on-site following a severe earthquake or flood;

– Structures enclosing or supporting the pipelines shall be designed as IL4 structures as defined in AS/NZS 1170;

– The pipeline shall resist damage from floods, river erosion and landslides.

2.5.2 Bridge design

As part of the pipeline will be supported by a bridge structure, GHD has adopted the requirements of the NZTA Bridge Manual 3rd Edition19 (the Bridge Manual) for the design. Although the primary purpose of the Bridge Manual is for bridges procured and constructed by Waka Kotahi, it is considered to be a solid basis of design for all structures at the IL4 importance level.

2.5.3 Seismic resilience criteria

Site specific seismic design criteria for the network arch bridge and pipeline have been provided through the completion of a Site Specific Seismic Hazard Analysis (SSSHA), completed by Tonkin and Taylor20. In summary, the

17 Table 2.1: Importance level and annual probabilities, Table 6A.1: Unweighted peak ground acceleration coefficients. Bridge manual (SP/M/022) 3rd edition, NZTA, 2016 18 IL4 assets are required “to be maintained in an operational state or are to be returned to a fully operational state within an acceptable short timeframe” following the SLS2 as defined in Clause 2.4 of NZS 1170.5:2004 (Part 5: Earthquake actions – New Zealand) 19 NZTA as now known as Waka Kotahi – so referred to as Waka Kotahi Bridge Manual, 3rd Edition, 3rd Amendment 20 Silverstream Pipe Bridge Site Specific Seismic Hazard Analysis, Tonkin & Taylor, December 2020


proposed structures have been designed to withstand the seismic events that correspond to each limit state described in Table 6 below.

Table 6 Limit State Definitions

Limit State Relevant Definition, as per NZS 1170 or NZTA Bridge Manual Corresponding event

Pipeline: Ultimate limit state (ULS)

NZS1170.5:2004, Clause 2.1.4: Ultimate limit state for earthquake loading shall provide for: Avoidance of collapse or loss of support to parts of categories P.1, P.2, P.3 and P.4 (Section 8);

1 in 2,500 year seismic event

Bridge: Damage Control Limit State (DCLS)

NZTA Bridge Manual, Section 5.4.2: After exposure to a seismic event of design (DCLS) severity, the structure shall be usable by emergency traffic within three days, although damage may have occurred, and some temporary repairs may be required to enable use by vehicles.

Pipeline: Serviceability Limit State (SLS2)

NZS1170.5:2004, Clause 2.1.4: Serviceability limit states for earthquake loading are to avoid damage to: In a structure with critical post earthquake designation (i.e. importance level 4) all elements required to maintain those operations for which the structure is designated as critical, are to be maintained in an operational state or are to be returned to a fully operational state within an acceptable short timeframe (usually minutes to hours rather than days) after the SLS2 earthquake as defined in Clause 2.4.

1 in 1,000 year seismic event

Bridge: Serviceability Limit State (SLS)

NZTA Bridge Manual, Section 5.4.2: The serviceability limit state (SLS) event: After an event with a return period significantly less than the design (DCLS) value, damage should be minor, and there should be no more than minimal disruption to traffic (e.g. temporary speed restrictions and temporary lane closures to facilitate repairs such as the reinstatement of deck joint seals).

It is important to recognise the section of pipeline supported by the bridge is not, by itself, resilient. It is resilient because the pipe bridge has been designed to be resilient. As damage sustained by the pipeline during a seismic event cannot be quantified exactly, it is important for the pipeline to be designed to be easily accessible for repair and maintenance following a seismic event. If the pipeline is damaged during a seismic event, the bridge offers an indispensable platform on which to repair the pipe over the river and the Fault. Without the bridge it would not be possible to reinstate the pipeline in the river and across the Fault without major works that will require months to complete.

2.5.4 Flood Risk

The following sections detail the flood resilience standards which have been applied to the design of the bridge and the in-ground pipeline. While a specific design flood standard has not been specified the bridge design must comply with the GWRC Hutt River Floodplain Management Plan 2001 (HRFMP)21.

21 http://www.gw.govt.nz/assets/Our-Services/Flood-Protection/Hutt/FP-Hutt-River-FMP.pdf


2.5.4.1 Pipe bridge

The proposed pipe bridge is situated in an area that has an Erosion Zone (or Erosion Area)22 extending 80 metres outwards from the edges of a modelled design channel. These Erosion Zones identify the areas where the river channel is expected to migrate and where this will be allowed without any intervention (re-alignment or management to constrain the channel). The HRFMP prescribes that any structure constructed inside this Erosion Zone must be maintained by the asset’s owner. In this case, WWL will maintain the pipe bridge. All of the bridge piers and the eastern embankment are located within the 80 metre Erosion Zone as it is not feasible to build a bridge that spans this full width given the position of Eastern Hutt Road and the rail line.

The HRFMP sets the design criteria for any new bridges across the Te Awa Kairangi/Hutt River. Policy 15 of the HRFMP requires any new or replacement bridges to provide for a 2,800 m3/s (cumec) river flood capacity without adversely affecting flood defences or raising upstream flood levels. This sets the design height of the new bridge above the river which consequently dictates the number and size of the bridge piers and abutments. As noted above, for the design of the bridge, the Project has also adopted the requirements of the Bridge Manual as the recognised best practice standard for bridge design.

The HRFMP exceeds the design requirements within the Bridge manual for flood risk, and therefore the bridge has been designed in accordance with this more conservative requirement. For the 2,800 m3/s (cumec) event, the bridge structure and pipe will not be compromised as the bridge deck is above the predicted flood level.

2.5.4.2 In-ground pipeline

In the absence of a specific design flood criteria for the in-ground pipeline, a risk-based approach that considers both seismic and flood events together has been applied to the Project design23. To quantify and compare the risk levels, the flood and river erosion risks to the in-ground portion of the pipeline in the 1 in 100 year ARI flood event and the 2800 m3/s flood event have been evaluated.

2.5.5 Provisions for climate change

Design levels for the bridge have been provided by GWRC Flood Protection and correspond to a 2,800 m3/s flow rate consistent with the HRFMP. The HRFMP is based on risk assessment (and acceptable levels of service); the 2800 m3/s standard has been set by GWRC Flood Protection to incorporate the risk caused by climate change through to at least 2090. GWRC Flood Protection has advised that it is unlikely there will be a requirement for an increase in the design standard over the next 70 plus years.

GWRC has advised that freeboard to the underside of the superstructure is to be a minimum of 1900 mm consistent with the HRFMP, made up of 900 mm freeboard and 1000 mm for debris clearance. The Bridge Manual requires the bridge to be designed for a 1 in 2500 year flood event with a 1200 mm freeboard.

The HRFMP requires an additional 700 mm of freeboard to that required by the Bridge Manual. Over the life of the bridge, the additional 700 mm of freeboard required by the HRFMP is expected to accommodate any increase in flood levels due to climate change.

2.6 Consenting strategy – Project sections

While the original approach was to consent the Project in its entirety, the requirement for WWL to allocate project budget and commence construction within Financial Year 2020 - 2021 (ending in June 2021) or lose available funding to complete the Project required a change in approach to delivering the Project. The Project

22 The GWRC HRFMP defines the Erosion Zone as “land that is being actively eroded by the river… the Alluvial Erosion Area width is based on the effects of two or three large floods occurring in quick succession” (page 221). 23 See email correspondence from John Duggan, WWL, dated 2 July 2021, attached as Appendix B of Detailed Design Report (Appendix A)


was subsequently split into four sections to ensure elements of the Project could be brought forward enabling construction to commence before June 2021.

In determining how to split the Project into sections the following criteria were applied:

– where possible, the relevant section traverses a single territorial authority.

– sections can be independently constructed and then easily incorporated into the wider Project should the Project proceed in a staged manner.

– The wider pipeline replacement project has been split into four sections for consenting purposes. These sections consist of the following, and are shown in Figure 2 above.

• Section 1: Kaitoke pipeline extension – from the existing Kaitoke Main valve chamber on Fergusson Drive to the new bridge connection

• Section 2: Kingsley main – extending from Kingsley Pump Station on Reynolds Bach Drive to the new Kaitoke main section at the new bridge connection

• Section 3: New bridge over Te Awa Kairangi/Hutt River

• Section 4: Manor Park Extension – connects the new pipeline over the bridge to the existing Kaitoke Main cross-connection under the rail corridor through construction of a new pipeline through Manor Park Golf Course

– These sections were then split into two stages for consenting:

– Stage 1: Sections 1 and 2 – Non-notified resource consent for works on the true left bank of Te Awa Kairangi/Hutt River, Eastern Hutt Road and Reynolds Bach Drive

– Stage 2: Sections 3 and 4 – Notified consent for the pipe bridge, associated earth embankments and new pipeline through Manor Park – the consent to which this AEE relates.

2.6.1.1 Stage 1

Sections 1 and 2 were chosen to be brought forward and consented on a non-notified basis as these sections require relatively minor construction works and are able to operate independently of the pipe bridge and the new pipeline through Manor Park. Completion of Sections 1 and 2 will immediately increase the resilience of the water supply to Stokes Valley through an improved network between Kingsley Pump Station and the Kaitoke Main on Fergusson Drive.

2.6.1.2 Stage 2

Because of the likely wider public interest in the new pipe bridge (Section 3) as a result of the changes to natural character and amenity values in the popular Te Awa Kairangi/Hutt River corridor, and the challenge to identify all persons who may have an interest in the Project greater than that of the general public, WWL requests public notification of Sections 3 and 4. Section 4 cannot be ‘livened’ or operated without the presence of a new pipeline over Te Awa Kairangi/Hutt River (Section 3) to connect Section 1 with Section 4, which requires the construction of the pipe bridge, or an alternative connection to the Kaitoke Main. For this reason, WWL decided to consent Sections 3 and 4 together as one notified application.

This AEE comprises Stage 2 of the resource consent applications being sought for the Project.

2.6.2 Status of Stage 1 consents

Resource consent for Sections 1 and 2 were lodged with GWRC and UHCC on 19 March 2021, with no resource consents required from HCC. UHCC granted land use consent on 10 May 2021. However, changes to the design of the aerial crossing and erosion protection approach for scour discharges at Hulls Creek have delayed the


processing of the regional consents required24. Nevertheless, construction of the sections of underground pipeline where regional consents are not required, is currently being progressed.

24 As at 23 August 2021 the regional consents had not been granted however draft conditions had been circulated and agreed and the approval of the regional consents was deemed imminent.


3 Description of the existing environment

3.1 Introduction

The Project area extends from SH 2 in the west across Te Awa Kairangi/Hutt River to the interface with Eastern Hutt Road in the east. The Project area is illustrated in Figure 1 and Figure 2 (above) and included in Appendix B.

The specialist technical assessment reports found in Appendix C to Appendix H of this AEE provide detailed descriptions of specific environmental features relevant to each discipline.

The description of the existing environment covers the Project area as well as areas beyond the Project area that are impacted by the Project. The description of the existing environment is divided into the following themes:

– General site location and description

– Cultural

– Landform

– Water

– Ecology

– Transport

– Built environment

3.2 General site location and description

The general area of works is alongside and over Te Awa Kairangi/Hutt River at Silverstream, south of the Silverstream road and rail bridges. The proposed pipe bridge is aligned perpendicular to the flow of the river. The proposed pipeline through Manor Park Golf Course will traverse from the base of the bridge on the true right (western) bank of Te Awa Kairangi/Hutt River and proceed through the golf course until it meets an existing cross-connection beneath the rail corridor and SH 2.

3.2.1 Location and zoning

The Project is located at the northern boundary of Hutt City Council and the southern boundary of Upper Hutt City Council. The proposed pipe bridge will be located over Te Awa Kairangi//Hutt River, crossing the jurisdictional boundary between Upper Hutt City Council and Hutt City Council. A figure showing the district council boundaries is provided as Figure 4 below (also see Appendix B).


Figure 4 Council Jurisdictional Boundaries

Figure 5 Plan Zones, Overlays and Notations


The Project footprint is subject to a number of district planning zones, and both district and regional overlays and notations. These are identified in Table 7 and shown in Figure 5 above and Figure 6 below (also see Appendix B).

Figure 6 Flooding overlays from the UHCC DP and HCC DP

Table 7 Plan Zones, overlays and notations

Zoning/planning notation Comment

Greater Wellington Proposed Natural Resources Plan (Appeals Version 1 July 2021)

Ngā Taonga Nui a Kiwa (Schedule B)

Te Awa Kairangi/Hutt River is listed as Ngā Taonga Nui a Kiwa for both Ngāti Toa and Taranaki Whānui for the following reasons:

– Ngā Mahi a ngā Tūpuna (the interaction of mana whenua with freshwater for mana whenua purposes)

– Te Mahi Kai (places where mana whenua manage and collect food and resources) – Wāhi Whakarite (sites and activities where particular practices and activities take place) (Taranaki

Whānui) – Te Mana o te Tangata (a water body with value to all those who interact and rely upon it) – Te Manawaroa o te Wai (the potential for a water body to be restored following historic pollution) – Te Mana o te Wai (a water body inherently connected to the identity and mana of the area) – Wāhi Mahara (a place of learning where local knowledge and history are etched) (Taranaki

Whānui)

Statutory Acknowledgement (Schedule D)

Te Awa Kairangi/Hutt River is subject to Statutory Acknowledgements in respect of both Ngāti Toa and Taranaki Whānui.

Ecosystem and habitats with significant indigenous

Te Awa Kairangi/Hutt River is listed as having significant indigenous ecosystems, due to the following criteria:


Zoning/planning notation Comment

biodiversity values (Schedule F1)

– High macroinvertebrate community health; – Habitat for indigenous threatened / at risk fish species; and – Habitat for six or more migratory indigenous fish species. The following indigenous fish species have been recorded in the catchment:

– Bluegill bully, common bully, Cran’s bully, dwarf galaxias, giant bully, giant kokopu, inanga, koaro, lamprey, longfin eel, redfin bully and shortfin eel.

Regionally significant primary contact recreation (Schedule H1 and H2)

Te Awa Kairangi/Hutt River is listed in: – Schedule H1 as being a significant contact recreation freshwater body, and

– Schedule H2 as having a priority for the improvement of water quality for contact recreation and Maori customary use.

Important trout fishery rivers and spawning waters (Schedule I)

Te Awa Kairangi/Hutt River is listed as an important trout fishery river and spawning waters in Schedule I (Map 22a)

Surface water community drinking water supply protection areas (incorporates Schedule M1)

Te Awa Kairangi/Hutt River is listed as a surface drinking water supply (river). The abstraction consent is held by GWRC, and the water supplies the Wellington metropolitan area

Operative Regional Freshwater Plan

Rivers with Important Trout Habitat

Te Awa Kairangi/Hutt River is listed as having important trout habitat in Appendix 4 of the RFP.

Water bodies with regionally important amenity and recreational values

Te Awa Kairangi/Hutt River is identified as a water body with regionally important amenity and recreational values in Appendix 5 of the RFP.

Upper Hutt District Plan

Open Space Zone Construction of the pipeline and bridge abutments and embankments, including works within road reserve within UHCC jurisdiction on the eastern side of the river fall within the Open Space Zone

100 year flood extent The majority of the Project footprint within UHCC jurisdiction will be within areas which are subject to the 1 in 100 year flood extent overlay.

Hutt City District Plan

River Recreation Activity Area

Construction works on the western side of the river including the location of bridge abutments and earth embankments are located in the River Recreation Activity Area. The existing pipeline over Silverstream Bridge is also located within the River Recreation Activity Area.

General Recreation Activity Area

Construction works on the western side of the river, including the earth embankments and the new section of pipeline running alongside the rail corridor are located with the General Recreation Activity Area

Wellington Faultline Special Study Area

The Wellington Faultline Special Study Area (Special Study Area) overlay is intended to manage the risk of a fault rupture on development caused by ground deformation. The new pipeline parallel to SH 2 and areas of the bridge structure are located largely within the Special Study Area.

3.2.2 Designations

In addition to the planning notations identified above, construction activities will also be undertaken both within and adjacent to the following designations under the HCC DP:

– NZR3, for Railway Purposes - Wairarapa Railway with New Zealand Railways Corporation (KiwiRail) as Requiring Authority; and

– TNZ1, for Motorway Purposes with Waka Kotahi as Requiring Authority.

The extent of these designations is shown in Figure 7 below. The proposal will require construction works within the NZR3 and TNZ1 designations, associated with the connection of the replacement pipeline through Manor


Park Golf Course to the existing cross-connection within the rail corridor, and connecting the cross-connection to the existing Kaitoke main on the eastern side of SH 2.

There are no designations within UHCC jurisdiction affected by Project works.

Figure 7 Designations for HCC and UHCC in the vicinity of works

3.3 Cultural

As noted above, Te Awa Kairangi/Hutt River is Ngā Taonga Nui a Kiwa to tangata whenua (large freshwater entity from which mana whenua derive cultural and spiritual identity), treasured by Māori for the abundant food resources it provided, and the access it gave to the vast forest across the valley floor.

3.3.1 History

Taranaki ki te Upoko te Ika (Taranaki Whānui) hold mana whenua over Te Awa Kairangi/Hutt River and derive cultural and spiritual identity from the river. Prior to European settlement, Maori travelled in the Hutt Valley largely by waka – many kainga and pā were close to the river. Te Awa Kairangi/Hutt River linked the settlements and provided a food supply. Mahinga kai were found along the river such as at Petone, which was a wetland that held abundant resources of birds, tuna and other food sources. Waka were carved from forest trees felled for that purpose close to the river.

Te Runanga o Ngāti Toa Rangatira (Ngāti Toa) also have long-standing associations with Te Awa Kairangi/Hutt River. The iwi claim associated with the river from the time of their participation in the invasion of the Hutt Valley during 1819 and 1820. Although Ngāti Toa Rangatira did not remain in the area after this invasion, Te Awa Kairangi/Hutt River continued to be important to the iwi following their permanent migration and settlement in the lower North Island in the late 1820’s and early 1830’s.


Maori historically used Te Awa Kairangi/Hutt River to travel through the Hutt Valley in their waka, and used the hinterland to hunt, gather kai and timbers for works including the building of waka, pā palisades and other structures. Historically, the flora and fauna of the river was vital for survival of Maori and although this significance has lessened over time, the cultural significance to mana whenua remains.

3.3.2 Values

Te Awa Kairangi/Hutt River is valued by both tangata whenua who continue to reside in the region, adjacent communities and visitors. Today, the river is still regularly used in summer for fishing through iwi traditional harvesting rights, including for whitebait – juvenile inanga, kokopu and eeling. The river therefore continues to be valued for the provision of mahinga kai.

The community value Te Awa Kairangi/Hutt River for the sense of place it provides and its recreational and scenic values, embodied in the popularity of the Hutt River Trail, which provides opportunities for recreation in the environs of the river.

3.4 Landform

The Assessment of Natural Character, Landscape and Visual Effects (Appendix G) includes a detailed description of the existing natural character and landscape environment, with a summary provided below.

3.4.1 Landscape and visual

The Hutt Valley comprises a broad valley, formed within a wider landform system of steep and elevated ridges, hill country, valleys and basins, and lower coastal areas influenced by Wellington Harbour and coastal processes. The Tararua and Remutaka Ranges broadly enclose the Hutt Valley to the north and east. Landforms surrounding the Hutt Valley to the east and west comprise steep-rolling hill country – being the hills between Upper Hutt and Mangaroa, the Haywards Hills, and the eastern hills between Hutt Valley and Wainuiomata. To the immediate west of Te Awa Kairangi/Hutt River is the Wellington Fault.

The Project area is contained within the Hutt Valley Character Area as identified within a previous Hutt Landscape Study25. Te Awa Kairangi/Hutt River is the dominant element of this defined landscape character area and in combination with the Wellington Fault has been instrumental in the formation and character of the entire valley floor. Within the Project area, Te Awa Kairangi/Hutt River’s path follows the Wellington Fault. Te Awa Kairangi/Hutt River only starts to separate from this landform in the lower reaches, as it runs towards Wellington Harbour.

The Project area is located between an existing wastewater weir downstream and the Silverstream road and rail bridges upstream. These structures introduce substantial existing modification directly within the active riverbed and adjoining river margins at this location.

Te Awa Kairangi/Hutt River at this location is popular for fishing and other recreational uses within the river corridor, as the gravel beaches provide direct access to the water.

3.4.2 Geology

Ground conditions at the site are summarised in GHD’s Geotechnical Interpretative Report26 and are briefly summarised below.

25 Hutt Landscape Study April 2012, prepared by Boffa Miskell Ltd 26 Silverstream Pipe Bridge Geotechnical Interpretive Report (July, 2021). This report, and the appendices to this report have been used to inform the design of the bridge and are referenced in the Detailed Design Report and are available upon request.


Each side of the river is characterised by Holocene alluvium, primarily sandy gravel, overlying basement greywacke rock at depth. The material on the true right is much thicker due to a combination of natural river terraces and historical filling with reworked alluvial gravels from nearby. However, this material is considerably weaker than that on the true left bank due to proximity to the Wellington Fault.

3.4.3 Contaminated land

In October 2019, a Preliminary Site Investigation (PSI) for the proposed works across the entire Site identified two HAIL activities that are more likely than not to have been undertaken across the Project area. These activities, included the following:

– HAIL Category F6: Railway yards – evidence of both modern and historic railway tracks and railyards adjacent to the Site, which was obtained during the aerial photo review.

– HAIL Category A10: Pesticide use (adjacent to the alignment) – Golf course between the railway line and Hutt River which may have been subject to spraying of pesticides and herbicides.

A Detailed Site Investigation (refer Appendix C) was undertaken to determine the contamination levels of the following contaminants potentially present based upon the HAIL Categories:

– Trace elements (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn), associated with the nearby railway.

– Hydrocarbons including polycyclic aromatic hydrocarbons (PAHs), phenols/creosote, and solvents, associated with the nearby railway.

– Asbestos in soil, associated with building demolition material associated with the fill material that had been placed on Site and/or brake lining dust from the railway.

– Organochlorines and organophosphate pesticides (OCP and OPP), which is associated with the golf course on parts of the Site.

In accordance with Regulation 7 of NES Soil, the DSI has concluded that the measured concentrations of the potential contaminants are considered to be low and are unlikely to pose a risk to human health and the environment now or in the future.

3.4.4 Natural Hazards

The Project area sits across the Wellington Fault. The Wellington Fault extends from a point south of the Wellington Heads to a point north of Te Mārua water treatment plant. Rupture of the Fault is expected to occur along the entire length of this block. The Fault is a right lateral strike-slip fault and has dextral displacement (in other words when standing on either side of the Fault the opposite side of the Fault moves to the right).

The location of the Fault, connected between known locations, is shown in relation to the proposed pipeline in Figure 8.


Figure 8 Known locations of the Wellington Fault

Fault rupture, ground-shaking, liquefaction, lateral spreading, regional uplift/subsidence and slope instability are all seismic risks associated with the Wellington Fault.

3.4.4.1 Fault rupture

The Wellington Faultline Study Zone27 is located within the Project area. This zone covers 75 m either side of the inferred trace of the Wellington Fault at ground level, reflecting the uncertainty of the exact location of the Fault below ground and where fault rupture will express itself at ground surface should the Fault rupture.

3.4.4.2 Ground shaking

In addition to the Wellington Fault, the Wairarapa Fault, Ohariu Fault and Hikurangi Subduction Zone are other significant known active faults nearby. Rupture of any of the above faults would result in varying levels of ground shaking at the subject site.

3.4.4.3 Liquefaction

The liquefaction vulnerability is generally low across the site, due to groundwater and ground conditions. Potential for liquefaction varies significantly between different earthquake events but for the design event discussed in this report the Eastern Hutt Road embankment is identified as the only potentially liquefiable zone, with potentially liquifiable material encountered at up to 3.2 m BGL.

3.4.4.4 Lateral spreading

Lateral spreading only occurs in the case of liquefaction. The potential for lateral spreading is therefore generally low across the site. Some lateral spreading may occur at the Eastern Hutt Road embankment.

27 An area where land use is managed for natural hazard risk in the Hutt City Council District Plan


3.4.4.5 Slope instability

There is some seismic induced slope instability on the rail corridor embankments and the existing embankment on Eastern Hutt Road. The extent of slope instability will depend on the magnitude of the seismic event occurring but for the design earthquake considered here some minor slope instability is expected.

3.4.4.6 Flood and erosion hazard

Te Awa Kairangi/Hutt River is prone to flooding, and the flood problem has been exacerbated by development in the Hutt Valley, constraining the river. The HRFMP estimates the risk of various flood events over the next 100 years as follows:

– 1 in 100 year flood (1,900 cumecs) – 63% chance, about two in three

– 1 in 440 year flood (2,300 cumecs) – 20% chance, one in five

– Rare flood (2,800 cumecs) – 4% chance

The lower reaches of Te Awa Kairangi/Hutt River are managed and modified with extensive bank protection works undertaken in the river over time resultingin a well defined and contained river corridor which is deliberately constrained along a fixed alignment.

At Silverstream the erosion of the banks is managed through willow plantings and provision of light rock armouring close to the existing road and rail bridges. This is in comparison to the river in lower reaches where heavier structural engineering features, such as rock lined banks, concrete blocks and groynes have been implemented to protect infrastructure and private property from erosion.

3.5 Water

3.5.1 Existing state of Te Awa Kairangi/Hutt River

Te Awa Kairangi/Hutt River flows through the length of the Hutt Valley from the headwaters within the Remutaka mountain range to Wellington Harbour. The Te Awa Kairangi/Hutt River is heavily managed for much of its length within the Hutt Valley, including in the proposed bridge location. Here, the river is relatively straight and with the main floodway confined between the Manor Park Golf Course (west bank) and Eastern Hutt Road (east bank).

The river channel is approximately 75 m wide at the proposed bridge location, although in periods of low flow the river meanders within this width. The current river channel is bounded on either side by an 80 m Erosion Zone (or Area). It is understood that the position of the current river banks will not be maintained within the Erosion Zone and that the river channel will be allowed to migrate within this area. Discussions with GWRC Flood Protection have identified measures will not be taken to prevent the active river channel from moving into this area.

Edge protection, in the form of planting, is in place along both banks of the river in the area of interest. Just upstream of the proposed bridge location are two existing bridges, the rail bridge and Silverstream road bridge where the existing bulk water pipeline is currently attached.

Downstream of the proposed location there is a weir within the river channel, the weir has been constructed to retain a large wastewater pipeline. The effective stop banks of the Hutt River in this location are Eastern Hutt Road to the east, and to the west of the river the effective stop bank is the KiwiRail rail embankment.


In 2010, GWRC produced a summary report presenting data from various gravel surveys between 1987 and 2009. The report notes the overall trend of degradation downstream of the Silverstream wastewater crossing. Upstream of this, the gravel tends to be aggrading with some localised sections of degradation (Gardner, 2010).28

Te Awa Kairangi/Hutt River displays a pattern typical of most rivers: erosion and transport of sediment in the upper catchment, conveyance through the mid reaches, and deposition in the lower reaches and at the mouth. Although numerous tributaries flow into Te Awa Kairangi/Hutt River, few of these are natural and only one tributary is located within the Project area (refer to section 3.6.2.2 below).

3.5.1.1 Water quality

GWRC has established long term water quality monitoring sites on Te Awa Kairangi/Hutt River, one at Manor Park just downstream of the Project area, and one at Boulcott further downstream of the Project area. GWRC (Heath & Greenfield)29 and Aquanet (Greer and Ausseil 2018)30 have recently undertaken a comprehensive review of the current state and trends of water quality.

The water quality data indicates that water quality within the Project area is generally good, showing low to moderate nutrient concentrations and low contaminant levels, with many parameters analysed being below the level of detection. Observed median nutrient values were below relevant attribute and guideline levels; dissolved oxygen, temperature, and clarity were at a level that would not affect the ecological health of Te Awa Kairangi/Hutt River. Previous GWRC analysis concluded that both the Boulcott and Manor Park sites had excellent water quality.

3.5.2 Management of Te Awa Kairangi/Hutt River

Te Awa Kairangi/Hutt River has a long history of river management by GWRC Flood Protection (and its predecessors) to achieve flood protection and erosion control. These works are largely authorised by two consents; the GWRC existing river maintenance resource consent, reference number WGN130264 and consent number WGN110149 for the extraction of gravel at the river mouth. The main aim of the river management work programme is to:

– Establish and maintain Te Awa Kairangi/Hutt River within its design channel alignment as defined in the HRFMP;

– Maintain the flood capacity of the existing channel by removal of obstructions and gravel build-ups as necessary; and

– Maintain the integrity and security of the existing flood defences (including stopbanks and bank protection works).

In addition, the work programme also aims to maintain, or (where possible) improve, the in-river and adjacent riparian environment on a reach-by-reach basis.

These management activities occur from the coastal marine area for the extraction and the upstream side of the Estuary Bridge, Waione Street, Petone to the eastern end of Gillespies Road, Upper Hutt, a reach of approximately 28 km.

28 Gardner, M (2010), Hutt River floodplain management plan – Hutt River Gravel Analysis 1987 -2009, Greater Wellington Regional Council Report, Reference N/03/09/05, June 2010. 29 Heath MW and Greenfield S (2016) Benthic cyanobacteria blooms in rivers in the Wellington Region: Findings from a decade of monitoring and research. Greater Wellington Regional Council, Publication No. GW/ESCI-T-16/32, Wellington. 30 Aquanet Consulting Ltd. (2018). Whaitua Te Whanganui-a-Tara River and stream water quality and ecology. Report Prepared for Greater Wellington Regional Council


The existing flood management activities are undertaken by GWRC Flood Protection in accordance with a Code of Practice and conditions of the existing resource consents noted above.

3.5.2.1 Maintenance of channel alignment

Structures

Channel alignment is maintained using a combination of ‘hard edge’ protection works (e.g. rock rip-rap linings or groynes), ‘soft edge’ protection works (e.g. planted, layered or tethered willows and debris fences), mechanical shaping of the beaches and channel by ‘ripping’ or recontouring, and channel diversion cuts.

Groynes are impermeable structures that project out from the bank edge to deflect the flow of water. Stockpiles of rock/concrete blocks are held adjacent to the river at a number of sites for urgent works during or after a major flood event.

Rock lining consists of rock boulders placed against a section of river bank to form a longitudinal wall that armours and protects the softer bank material behind it from scouring and erosion.

Permeable erosion protection includes the construction of debris fences, permeable groynes, and debris arresters. Debris fences extend from the bank into the river channel and are used to support the creation or re-establishment of a willow buffer zone along the edge of the river channel, to maintain channel alignment. These debris fences are interplanted with willows; once established, the fences and willows trap flood debris, and slow flows and gravel movement. Without debris fences, willows are more vulnerable to flood damage and are less likely to establish.

Mechanical shaping

Beach ripping involves dragging a prong behind a bulldozer to loosen up the upper surface layer, or armour layer, of the beach. Beach ripping is undertaken on dry beaches to loosen the gravels and encourage mobility during future high flows or floods when the beach is inundated. Ripping helps prevent the formation of channel distortions and reduces lateral bank erosion.

Beach recontouring involves more extensive movement and redistribution of the gravels. It is also carried out on the dry bed and is used to streamline and shape a beach to avoid any future obstructions to flow.

Bed recontouring is the mechanical shaping or realignment of a section of the active bed. It is used to establish or maintain a design stream alignment and/or reduce erosion. It may involve moving material from a dry beach into the wet channel and/or moving the material from the wet channel onto a dry beach, to achieve a new channel form. It is used as an alternative to the construction of permanent structures such as groynes or rock lining in the first instance.

Maintenance of channel capacity

Various tools are used to maintain river channel capacity, including beach scalping, removal of vegetation and flood debris, and gravel extraction. Beach scalping involves the mechanical clearance of weeds and grasses from gravel beaches. Vegetation reduces flood flow velocities which can encourage gravel aggradation and reduce channel capacity. Large machinery is used to remove the vegetation and loosen the armouring layer.

Removal of vegetation from beaches is done throughout the 28 km reach every year on an ‘as required’ basis and usually in conjunction with beach ripping. Unwanted willows or other species including weeds are removed from the channel to minimise the potential for blockages during floods, or to prevent dislodged willows re-growing in the channel.

Removal of flood debris can include removing trees, slip debris, collapsed banks and remains of structures but does not include normal gravel build up. Flood debris blockages reduce channel capacity and can deflect flood


flows into banks causing lateral erosion. Flood debris removal is normally undertaken after each significant flood event.

Regular gravel extraction is also undertaken to maintain channel capacity. Gravel bed material is extracted from Te Awa Kairangi/Hutt River to maintain bed levels to a design profile within an envelope of maximum and minimum levels, which corresponds to the approximate riverbed level present in 1998. The aim is to maintain a balance between flood capacity (reduced by higher bed levels) and the threat of undermining bank protection works (increased by lower bed levels). Material is excavated from the beaches where possible, and from the active channel. The existing gravel extraction activity is determined by regular bed level surveys and gravel volume assessments.

3.5.3 Groundwater

Te Awa Kairangi/Hutt River plays a significant role in the hydrogeology of the groundwater system as it is the main recharge source to the underlying aquifer system. The hydrogeological conditions of the Project area are described in detail in the Assessment of Dewatering Effects attached as Appendix D of this report.

Te Awa Kairangi/Hutt River is listed as a surface drinking water supply under the PNRP and the Project area also spans the Upper Hutt Category A and Lower Hutt Category B Groundwater Zones of the PNRP.

Intrusive ground investigations have been undertaken in several stages across the wider Silverstream project site between 2016 and 2021. The ground conditions encountered across the site are summarised as:

– Alluvium: Deposited on either side the Hutt River, alluvium deposits primarily comprise a medium dense to dense sandy gravel with varying degrees of silt. This is generally presented from the ground surface in thicknesses of 3 to 14 m (but has been encountered to depths >20 m BGL). This alluvial material is overlain by thin layers of silt / sandy silt in some areas of the site.

– Greywacke (basement) rock: Wellington Greywacke underlies the overburden alluvium at the site. It generally consists of fine-grained sandstone and argillite. The Greywacke is generally highly fractured into 5 – 40 mm angular clasts, cemented by quartz infill, with occasional black clay/weathered argillite bands. The weathering profile (depth to slightly weathered rock) varies across the site.

Groundwater monitoring has been undertaken between the 16th of December 2020 and 4 June 2021. Groundwater has been encountered at depths as shallow as 0.9 m BGL extending up to 8 m BGL. Monitoring has confirmed that the groundwater is hydraulically connected to, and fed by, Te Awa Kairangi/Hutt River.

There are no known active water take consents (surface water or groundwater) within 500 m of the Project area. Manor Park Golf Course has a bore for irrigation located near the clubhouse (>500 m southwest of the alignment).

There are 23 bores or wells within 500 m of the alignment. The bores are generally shallow with bore depths ranging between 3.4 to 18 m BGL. The location of the bores are shown in Figure 9 below.


Figure 9 Location of bores within 500 m of Project area (GWRC GIS portal31)

3.6 Ecology

The Project area lies within the Sounds-Wellington Ecological Region and the Wellington Ecological District. This Ecological District is characterised by steep, strongly faulted hills and ranges, the Hutt River floodplain, and the Wellington and Porirua Harbours.

The variety of landforms within the catchment provides a number of different habitats for fauna and flora. The Ecological Impact Assessment (Ecology Assessment) included as Appendix F includes a detailed description of the existing ecology, with a summary provided below.

3.6.1 Terrestrial Ecology

Vegetation that once covered the flood plain has been cleared over the last 150 years to facilitate development and infrastructure, including housing, industrial development, roading and rail infrastructurePrior to clearance, species such as raupo, flax and toetoe dominated the wetlands, and kahikatea, matai, pukatea and rimu forest grew extensively on the valley floor. Only fragments of native vegetation remain within the former flood plain.

Large contiguous areas of secondary native forest are located immediately adjacent to SH 2 however none of this forest is expected to be affected by project works.

The variety of landforms within the Project footprint provides a number of different habitats for fauna and flora. Desktop assessment and field work was undertaken to identify vegetation communities and their values in the project area, as described in the Ecology Assessment attached as Appendix F.

31 https://mapping.gw.govt.nz/gwrc/


Figure 10 Terrestrial community types within the Project area (from Appendix F)


3.6.1.1 Vegetation

The vegetation within the Project area is comprised of planted vegetation, including in patches along the eastern floodplain, the riparian margins, and along the railway corridor. In addition, recent planting has occurred on the western side of the river within the Manor Park restoration site which is confined by the Manor Park Golf Club, Te Awa Kairangi/Hutt River, and the rail corridor.

Mown grass is the primary vegetation type across the Project area, comprising the floodplain, on both banks of the river. Interspersed through the maintained grassy areas are patches of planted native scrub/shrubland and unmaintained areas comprising rough grassland/weed fields. Immediately bordering Te Awa Kairangi/Hutt River are a mixture of willows that have been planted to aid flood management.

Over the last 12-15 years Forest and Bird has planted native species in the river corridor and flood plain. Species such as karamu, flax and toetoe are now present, holding values for food and limited habitat for some bird species such as Tui.

The Project area has been split into specific terrestrial communities as shown in Figure 10 and outlined in the Ecology Assessment. These communities are summarised below.

3.6.1.2 Manor Park Golf Course restoration area

The plantings in this area are rank grasses and weedy vegetation, and exotic species still dominate the area. Therefore, this area is not representative of a natural community. There are large areas of blackberry present on the western side of the site, where clearance and planting has not yet occurred, as well as areas that are re-establishing throughout the plantings. There are no biological or physical features that are locally, regionally, or nationally scarce, At-Risk or Threatened.

The vegetation that has been planted does not have a natural diversity of ecological units, ecosystems, species, and physical features. The plantings are small and scattered over rank grass and (currently) do not provide connectivity or buffering for representative, rare, or diverse ecosystems and habitats. While known to provide habitat for a number of Not Threatened fauna species, it does not provide seasonal or core habitat for protected, At-Risk or Threatened indigenous species.

3.6.1.3 Railway Corridor

This vegetation community is very simple in diversity and structure, with the canopy almost a monoculture of māhoe (with occasional other broadleaves, tree ferns). While this vegetation is primarily native, there is a high presence of weedy and exotic tree species scattered throughout. It is not sufficiently representative of a naturally regenerating community or representative of the vegetation which would naturally occur in this location.

3.6.1.4 Native plantings (outside of riparian corridor)

This vegetation is described as planted (for amenity rather than ecological function) and simple in taxa richness, with no biological or physical features that are locally, regionally or nationally scarce or threatened.

The planted vegetation although containing some small simple patches of native species does not enhance connection or provide buffering for representative, rare or diverse ecosystems and habitats or provide seasonal or core habitat for protected, At-Risk or Threatened indigenous species.

3.6.1.5 Riparian plantings

The riparian vegetation has a mixture of planted willow and a selection of native species towards the landward edge. The assemblage is not representative of a natural river riparian community and there are no biological or physical features that are locally, regionally, or nationally scarce or Threatened.


While the riparian margins have some (but limited) role in buffering the river from surface run-off, and in supporting movement of species, the cover is not continuous, and the in-river functions are limited.

Riparian sections are likely to contain some (limited) useful habitat for macroinvertebrates and other fauna.

3.6.1.6 Exotic vegetation

On the eastern side of the river, beyond the riparian margin are considerable areas of managed (mown) grasses, with scattered poplars. Within the golf course (western side) there are a variety of exotic trees planted and scattered throughout. There is also a larger patch of exotic plantings present on the golf course.

These communities are induced and dominated by introduced species, many of which are naturalised and invasive. They do not provide important habitat for terrestrial native fauna or avifauna.

3.6.1.7 Potential wetland habitat

There is one area (5 m x 5 m) of slightly wetter appearance than other areas of rank grasses on the true right bank. There were no other depressions or contours or features suggestive of damp or rain collecting features and no indication of any wetland vegetation within the survey area. Given the surrounding land modifications and disturbances (e.g. railway line, blocked culverts, sediment deposition and access tracks) the potential wetland habitat is considered to be induced.

The area of potential wetland was surveyed in accordance with the Clarkson method32 and hydric soil testing was undertaken. The prevalence of Yorkshire fog and the dominance of facultative species (equally likely to be found in wet and dry soils) suggest this area does not provide suitable habitat for indigenous wetland facultative or obligate species.

The PNRP and NPS-FM exclude communities dominated (i.e. >50% coverage) by pasture species from the definition of a natural wetland33. Yorkshire fog is the main species present with an average cover of 70%, including contributing greater than 50% of the coverage in each of the 1 m2 sub-plots surveyed in the potential wetland area. The prevalence of Yorkshire fog (considered a pasture species) and the dominance of facultative species (equally likely to be found in wet and dry soils) suggest this area does not provide suitable habitat for indigenous wetland species.

This area is not considered a “natural wetland” according to the PNRP definition due to the large presence of Yorkshire fog and lack of other facultative and obligate wetland species.

3.6.1.8 Birds

A desktop review of published records of birds observed within the Project area, identified that between 2012 and 2015 GWRC conducted summer surveys of riverbed-nesting shorebird species along Te Awa Kairangi/Hutt River by dividing the river into 1 km sections and undertaking surveys identifying species and numbers of birds within each section. Across the entire length of the river, 44 bird species were recorded, including 26 native and 18 exotic species. Six sites of value for indigenous birds were identified on Te Awa Kairangi/Hutt River during these surveys but only one, extending from the Silverstream Weir to the eastern end of Awa Kairangi Park, is located in proximity of the Project footprint.

32 Clarkson, B. R. (2013). A vegetation tool for wetland delineation in New Zealand. Landcare Research for Meridian Energy Ltd. 33 While no list of “pasture” species is provided in the NPS-FM, GWRC has released a guidance document which includes what they perceive to be pasture species in the Wellington Region (refer: http://www.gw.govt.nz/assets/Biodiversity/Wetland-Technical-Determination.pdf).


No Threatened species were observed during the GWRC survey, which includes the Project footprint, or have been reported on e-Bird (a citizen science database), within and in close proximity to the proposed bridge location.

Of the 44 bird species recorded during the GWRC surveys, seven are currently classed as At Risk (black shag, royal spoonbill, pied shag, little black shag, variable oystercatcher, red-billed gull and whitehead). Although not observed within the Project footprint, it is likely that some of these species, particularly the shag species, occasionally use habitats within the Project area for foraging and roosting and they will likely travel through the Project area when traversing up and down the river corridor.

Site visits were undertaken to supplement the desktop information identified, this included walkovers in 2019 and surveys of shag populations in early 2021. During walkover on 20 August 2019 and the shag surveys between 23 March and 13 April 2021, 26 avifauna species were observed, including 15 indigenous species within the Project footprint. Of the 15 avifauna species observed only two were identified as At Risk or Threatened black shag and little black shag. All other species observed were Not Threatened.

The avifauna habitat within the Project area is not considered suitable, or core, habitat for nesting indigenous avifauna. The Project area may be used by avifauna for roosting, foraging, or resting; however, habitat is provided for these behaviours throughout the Te Awa Kairangi/Hutt River corridor.

3.6.1.9 Lizards

The DOC administered BioWeb herpetofauna database has records for seven lizard species within 5 km of the Project area within the last 20 years. However, there have been no lizard records within 1 km and only one record within 2 km, since 1999.

While not represented in the BioWeb database, lizard release has occurred at the “Manor Park restoration site” in 2018, as part of a restoration project by Forest and Bird. A total of 63 skinks of two varieties (copper skink and northern grass skink) were released in the floodplain north of Manor Park Golf Course. Both are common, robust and widespread species, with a conservation status of Not Threatened.

Site surveys undertaken by Boffa Miskell in early 2020 confirmed some of these lizards are still present within the Manor Park restoration site within the Project footprint. Populations are not anticipated outside of what may have survived following the release of lizards within the Manor Park restoration site but surveys have shown the northern grass skink population is recruiting, based on the presence of gravid females and juveniles.

While not surveyed, the mixed native and exotic arboreal vegetation within the railway corridor is considered unlikely to contain arboreal lizards. The vegetation is separated from potential source populations (in the Belmont Regional Park) by SH 2 and the rail line. This vegetation lacks complexity and suitable refugia and is subject to frequent disturbance from the golf course and the road/rail operations.

The arboreal vegetation alongside the Hutt River is also considered unlikely to harbour arboreal lizards. As with the vegetation along the railway, it is isolated from source populations, lacks complexity, and is exposed and subject to disturbance by river management activities, the nearby road and users of the Hutt River Trail.

In summary, the habitat within the Project area is not considered core habitat for lizard taxa but can be considered suitable habitat for Not Threatened terrestrial skinks.

3.6.2 Freshwater Ecology

3.6.2.1 Te Awa Kairangi/Hutt River

As described in section 3.5 above, Te Awa Kairangi/Hutt River throughout the Project area is a highly modified and managed system. This includes within the Project area where flows and gravel movements are influenced by


the Silverstream road and rail bridges upstream, and the wastewater weir downstream. Within the Project area, the bed of Te Awa Kairangi/Hutt River is approximately 70 m wide with river gravels dictating, and frequently altering, the wetted width of the river at any given time.

The section of Te Awa Kairangi/Hutt River (being downstream of the intake weir at Kaitoke) is not classified in the Regional Freshwater Plan as containing any special ecological values. Te Awa Kairangi/Hutt River is identified in the Regional Freshwater Plan and the PNRP as a ‘River with Important Trout Habitat’. Te Awa Kairangi/Hutt River is identified in Schedule F1 of the PNRP as having significant indigenous biodiversity values for supporting ‘High Macroinvertebrate Community Health’, ‘Threatened or At Risk Fish Habitat’ and ‘Migratory Fish Habitat’.

The New Zealand Freshwater Fish Database identifies that since 2000, 13 native freshwater fish species have been recorded in Te Awa Kairangi/Hutt River. Of the 13 native fish species, seven have a current At Risk conservation status. The most commonly recorded fish species has been longfin eel, shortfin eel and redfin bully.

Sections of the river within the Project area provide suitable habitats, including for spawning, for taxa such as the bully species. However, it is not particularly good habitat for taxa which prefer gravel habitats (and slower water), including for spawning, such as koaro and common smelt. Pebbles, cobbles, and boulders are the prominent substrate types within the Project area. Accordingly, some of the fish taxa observed within the catchment such as giant and banded kokopu are unlikely to reside within, or near, the Project area due to flow conditions (rates and depths) and lack of suitable habitat features.

The macroinvertebrate community composition is reflective of a relatively high value assemblage, and indicative of good/excellent water quality. Te Awa Kairangi/Hutt River provides habitat for a substantive assemblage of freshwater fish taxa, including migratory species, and species which spawn in or on gravel beds.

Overall, this section of Te Awa Kairangi/Hutt River is considered to provide fair-moderate habitat for indigenous aquatic fauna.

3.6.2.2 Unnamed tributary

The unnamed tributary is considered a highly modified stream that has been artificially straightened with flows now heavily influenced by existing structures under the rail corridor and SH 2. The unnamed tributary is not expected to comprise any rare or distinctive habitats and the macroinvertebrate community composition is expected to be indicative of poor-quality, soft-bottom streams dominated by tolerant taxa.

A perched culvert near the confluence with Te Awa Kairangi/Hutt River and ‘buried’ culverts under the railway and SH 2 infrastructure limits the habitat potential and habitation by aquatic fauna.

The condition of the unnamed tributary, when coupled with poor maintenance of existing infrastructure, does not provide suitable habitat opportunities for freshwater fish or sensitive macroinvertebrates. Flows are largely limited to slow-runs and fine sediment deposits prevail on the bed. The tributary is not expected to have a representative fish and/or macroinvertebrate fauna and does not provide an important connectivity function.

3.7 Built environment

3.7.1 Adjacent Land Uses

Land use on the eastern side of Te Awa Kairangi/Hutt River within the Project area is characterised by commercial, industrial activities and open space/reserve activities. The western side of the Project is framed by SH 2, the KiwiRail corridor, and Manor Park Reserve and Golf Course.

Along Eastern Hutt Road, to the immediate East of the subject site is a new industrial area. This area is zoned Business Industrial. This area was developed in c.2020 and is currently occupied by a range of business and


industrial users. To the south of this industrial area is a storage and pumping station for wastewater overflow operated by WWL on behalf of Upper Hutt City Council and Hutt City Council.

The rail corridor runs to the immediate north of the site and continues with a bridge over Te Awa Kairangi/Hutt River approximately 250 m north of the proposed bridge location. Similarly, SH 2 is to the north and west of the Project area, while the Fergusson Drive road bridge is approximately 330 m to the north.

There are no sensitive land uses near the site of works and the nearest occupied residential dwelling (on Reynolds Bach Drive) is approximately 450 m to the south.

There are several parks and reserves on both the left and right banks of Te Awa Kairangi/Hutt River. The Hutt River Trail is on the true left bank of the river. The true right bank of the river is not currently accessible to the general public.

3.7.2 Infrastructure and utilities

A number of other regionally and nationally significant utilities are located within and surrounding the Project area, including transmission and distribution networks for electricity, gas, wastewater, road and rail and telecommunications.

Below is a summary of the known services within the Project area:

– PowerCo: Strategic gas main along Eastern Hutt road in southbound lane

– Chorus: multiple cables, including fibre run through Manor Park Golf Course parallel to the rail line

– FX Network: fibre cables predominantly in the rail reserve, one cable crosses State Highway 2 but is downstream of the of area of interest

– Transpower: one 110 kV overhead transmission line crosses the Hutt River to Haywards substation but is outside the area of interest

– Wellington Electricity: cables in southbound lane of Eastern Hutt Road

– HCC/ UHCC:

• The UHCC trunk sewer main is in the Eastern Hutt Road southbound lane and extends as far as the sewer crossing where it crosses to the western bank (via a weir structure in Te Awa Kairangi/Hutt River) and continues adjacent to the river through Manor Park Golf Course towards Lower Hutt.

• A trunk sewer running from Stokes Valley through to the Hutt River crossing on the west side of the Eastern Hutt Road.

• There are several stormwater pipes discharging to Te Awa Kairangi/Hutt River from Eastern Hutt Road. None of these are within the Project area and therefore are not affected by project works.

– Vodafone: cables are in the rail reserve and within Manor Park Golf Course.

– State Highway 2

– Hutt Valley Line/Wairarapa Line (owned by KiwiRail)

3.7.3 Hutt River Trail

Formal and informal paths for walking and cycling extend north-south along both banks of Te Awa Kairangi/Hutt River, including the highly popular Hutt River Trail. The Hutt River Trail runs alongside Te Awa Kairangi/Hutt River from Petone’s Hikoikoi Reserve to the Te Marua entrance of Kaitoke Regional Park, Upper Hutt. The Hutt River Trail runs the entire length of the eastern riverbank (29 km) and is popular for recreational use as well as for commuting by bicycle within the Hutt Valley.


Within the Project area the Hutt River Trail follows Eastern Hutt Road on berms as an un-sealed track. Footpaths are provided on both sides of Silverstream road bridge to facilitate pedestrian access across Te Awa Kairangi/Hutt River at Silverstream however this access is very narrow and located very close to live traffic so is not regularly used by pedestrians or cyclists.

3.7.4 Built heritage and archaeology

The Archaeology Assessment in Appendix H identifies there are limited historical resources for the area in question, making it difficult to determine what activities or occupations may have left an archaeological signature. The nature of past works, including the replacement of earlier roading and railway fabric is undocumented, making it impossible to determine with certainty whether pre-1900 fabric is likely to remain in situ. Additionally, while Māori occupation and use of the area is well attested, the absence of known Māori archaeological sites along this area of the river mean that the likelihood of encountering Māori archaeological material in the area is not well understood. While there are known traditions of Māori use and occupation of the area, there is no evidence for use of the specific area in question.

There are few recorded archaeological sites along the Hutt River, or near the proposed area of works. The remains of the 1903 bridge across the river, recorded as R27/535, located downstream of the Silverstream weir is the only known feature within proximity of the Project area (refer Figure 11).

Figure 11 Location of nearby archaeological sites

There are no other recorded archaeological sites within 2.5 km of the Project area. The majority of Māori archaeological sites in the Hutt Valley are located near the mouth of the river and although there are accounts of


Māori use of the river and surrounding valleys, there is no physical evidence that would indicate that any Māori archaeological remains would be encountered within the Project area.

The Project area falls within a series of dynamic low river terraces that have formed in recent decades, or within major road and rail corridors that have seen significant excavation and refurbishment over the years. It is unlikely that any pre-1900 road or rail fabric remains in situ within the proposed area of works.


4 Project description 4.1 Introduction

The Project consists of the design, construction, operation and maintenance of a replacement section of Kaitoke Main at Silverstream. Key components of the Project are as follows:

1. Construction of an approximately 100 m long main span pipe bridge, 66 m long western approach span and 36 m long eastern approach span across the river which includes pedestrian and cycling access

2. Bulk earthworks and ground improvement works

3. Construction of underground and above ground sections of pipeline

4. Associated works including lighting, pedestrian/cycle connections and landscaping within the Project area

The Project description below is based on the preliminary design and the methods identified during the early contractor involvement (ECI) phase of design. This information identifies an “envelope” (or worst-case scenario) of actual and potential effects of construction activities such as earthworks and vegetation clearance footprints that have been used as a basis for the environmental assessments. These assessments are outlined in the technical reports included as supporting information in this application (refer to Appendix C - Appendix H).

Project features and the associated envelope of effects related to construction works are described in further detail below.

4.2 Pipeline

4.2.1 Pipeline on the western side of the river

The Kaitoke Main pipeline through the Manor Park Golf Course has been designed to meet the following requirements:

Item Description

Structure Pipeline

Pipe Material Steel – concrete lined

Pipe OD 1,066.8 mm

Wall Thickness 9.5 mm

Location Between the Rail Corridor and Te Awa Kairangi/Hutt River

The alignment of the proposed pipeline, shown as the worst case scenario 12 m wide construction corridor along its length, is shown in the drawings contained in Appendix I. The pipeline will be installed by trench and lay method through Manor Park Golf Course. It will then connect into the existing cross connection under the rail corridor.

This cross-connection was constructed in 1998 during the upgrade of SH 2 and is located under SH 2 and the railway line, terminating in the embankment between the rail line and Manor Park Golf Course. The connection was capped at both ends and was never connected to the existing Kaitoke Main. The proposed new pipeline will connect into this existing pipe at the golf course end. A small area of works will also be required on the eastern side of SH 2 to liven the cross-connection to the existing section of the Kaitoke Main at this location.

Prior to the start of construction, the Contractor will be required to locate, inspect and pressure test the existing pipe section to ensure it meets the necessary performance requirements.


4.2.2 Pipeline on bridge

Where the Kaitoke Main crosses the Te Awa Kairangi/Hutt River and the Wellington Fault the pipeline has been designed to meet the following requirements:

Item Description

Structure Pipeline

Pipe Material Steel – epoxy lined

Pipe OD 914.4 mm

Wall Thickness 9.5 mm

Location On new pipe bridge crossing Hutt River and Wellington Fault

Installation Method. Installed on sliding bearings attached to bridge deck

4.2.3 Scour valves and chambers

Scour valves and chambers will be located at low points along the pipeline to allow the pipe to be drained for any required repairs or maintenance in future.

To protect the main pipeline from backflow contamination the scour valve assembly will consist of one high-pressure and one low-pressure valve with a non-return valve in between. The non-return valve will provide protection for the main pipeline from backflow from the scour valve chamber and an additional sluice valve will add an additional level of backflow prevention.

The exact location of scour valves and chambers and the type of discharge system (whether overland flow via open channel or piped) to convey flow from the main pipeline to the river will be confirmed as part of detailed design. However, the scour chamber will be large enough34 to allow for treatment (de-chlorination of the water) through dosing water in the chamber with sodium thiosulphate before the de-chlorinated water is discharged via the low level outlet to the discharge system. Erosion protection will likely be required at the discharge point regardless of the discharge system adopted, this is likely to be in the form of geotextile overlain by appropriately sized rock rip rap.

4.3 Pipe bridge

The proposed pipe bridge is shown in the plans in Appendix I and an artist’s representation of the bridge once completed can be found in the Graphic Supplement attached as an appendix to the Assessment of Natural Character, Landscape and Visual Effects (Appendix G). The construction of the bridge includes construction of earth embankments, the piles and abutments, and then placement of the new bridge superstructure atop the pier structures. The bridge will be lifted into place by cranes, which will require temporary encroachment by a crane into the river bed. The expected construction methodology for the bridge is described in section 5.

The proposed pipe bridge is comprised of an approximately 100 m long main span, a 66 m long western approach span which crosses the Wellington Fault, and a 36 m long eastern approach span (refer Figure 12 below and Appendix I). The bridge will carry a new watermain pipeline up to 914 mm (outside diameter) OD and 211 m long with provision for other network utilities to be installed in the future. The pipe bridge is situated on a straight horizontal alignment but on a 0.5% fall from Pier 3 to the western end and on a 2% fall from Pier 3 to the eastern end to assist with drainage of stormwater.

34 The dosing chambers have been designed to allow sufficient dosing or detention time of the chlorinated water at the peak expected flow rates in the scour outlets. Guidelines for calculating the required dosing flow rates and concentrations can be found in the Water NZ document Hygiene Practices to Prevent Water Supply Contamination (2019).


Figure 12 Elevation of the Silverstream Pipe Bridge


The central span is the 100 m long network arch bridge superstructure which comprises two high strength steel arches, with high strength steel lateral bracings and hangers to form a network arch arrangement, and steel concrete composite deck.

Both approach spans are steel truss bridges which comprise steel members and a concrete composite deck.

The superstructures are all supported by piled piers on either end. The piers are formed by four reinforced concrete piles. All the piles are keyed into the bed rock at the base and cast monolithically at the top with a reinforced concrete pile cap.

The pot bearings that support the network arch bridge and eastern approach bridge are fixed while the other pot bearings that support the western approach bridge are free sliding bearings allowing this bridge to horizontally rotate with the Wellington Fault rupture. A vertical steel pin is installed through the end diaphragm at either end of the western approach bridge to guide the bridge superstructure to rotate horizontally during Wellington Fault rupture.

The bridge is designed as ‘non-integral’ at either end with deck movement joints such that the approach fill (embankments) will not directly interact with the superstructure.

The bridge has been designed for pedestrian/cyclist live loads as defined by the Bridge Manual and for up to 10,000 kg gross weight maintenance vehicle live load as defined by NZS 1170.1.

4.3.1 Service provisions

The bridge cross section incorporates a 3.3 m wide pedestrian/cyclist shared path on the downstream side of the deck and a 2.6 m wide watermain operation and maintenance envelope.

The pipe bridge has been designed to carry the additional loads of two smaller service pipelines in the future. Services provided on the bridge include:

– 1 x 914 mm OD watermain pipeline

– 2 x 400 mm pipelines for other three waters services

– 2 x 100 mm diameter service ducts on the bridge deck for approved third-party utility services

– 2 x 50 mm ducts for lighting

The pipelines will be supported by a series of pipe supports that are installed on the surface of the reinforced concrete deck. The 914 mm pipeline will be constructed immediately after completion of the bridge. The additional pipeline(s) will be constructed only if required at some time in the future, with any required adjustments to the pedestrian/cyclist access to be made at that time.

4.3.2 Design, amenity and safety features

Design, amenity and safety features are illustrated in the Landscape Concept Plans contained in Appendix G Features proposed to be included in the final bridge design are summarised below.

4.3.2.1 Amenity features

Observation platforms are proposed to be located on the upstream and downstream edges of the eastern and western approach spans.

Seating structures and freestanding approach gateways at the eastern and western approaches are proposed. These features have been incorporated into the concept design plans and will be refined as part of detailed design in consultation with Mana Whenua and the community.


Recreation amenity features include but are not limited to pathways at the approaches on both sides of the bridge which provide an opportunity to improve connections to the existing and planned wider walking and cycling network.

Other amenity features will include planted areas and lizard habitat features.

4.3.2.2 Safety features

The bridge will include safety barriers with a barrier height of 1400 mm from the deck surface to the top edge of the top rail35. All rails will be round to minimise the potential for injury to users of the bridge. A 150 mm pedal clearance is also provided from top rail to post to minimise the potential for snagging of cycle handlebars or pedals.

4.3.2.3 Materials and finishes

Preliminary concepts for materials and finishes, including colours are shown in the Landscape Concept Plans contained in Appendix G.

The main superstructure elements are proposed to be fabricated from structural steel with an appropriate corrosion protection system (coating). The deck, substructure and foundations will be constructed from reinforced concrete and all concrete deck surfaces will include slip resistance.

4.3.2.4 Lighting

Lighting is proposed to ‘wash’ across surfaces to improve amenity and safety. To prevent damage, light fixtures will be located under rails and between posts, out of easy reach.

Lighting is also required to reduce the chance of birds using the river as a way finding landmark at night colliding with the bridge profile, in particular reducing the risk of birds colliding with the cables in the network arches.

4.3.3 Maintenance

All the primary load carrying elements of the pipe bridge are adequately designed and detailed in such a way that little maintenance is required for the duration of the 100-year design life.

All permanent structural elements of the bridge have been designed to have a design life of 100 years. Replaceable elements such as bridge bearings and movement joints have been designed with a life of 40 years before the first major maintenance or replacement is required.

4.3.3.1 Access for inspection and maintenance of the pipeline

All parts of the structure, except buried surfaces and abutment backwalls, are accessible for the purposes of maintenance, repair and inspection. Elevated work platforms affixed to the bridge will be required and provision will be made for a mobile scaffold platform, using a trolley system, under the network arch main span. Replacement pipe and major fittings would be either craned directly onto the bridge or moved on the bridge using wheeled lifting plant.

Access to the abutment pads, deck edges and all other areas of the deck will be via readily available proprietary access equipment, such as mobile platform equipment located at riverbank, or via mobile under-deck gantry scaffold. The arch will be designed to support a working platform for replacement of the deck hangers.

35 Consistent with clause B2.5 of the Bridge Manual to protect cyclists from falling.


Ramps in the form of access embankments are provided at each end for access to the deck level for light maintenance vehicles, including elevated work platforms with the deck having been designed to support up to 10 tonnes in total weight.

In the case where there is only one pipe on the bridge, the clear side of the deck will be used for maintenance vehicle access. In the case where a future pipeline is constructed on the bridge, access will be via the clear space between the pipes.

4.4 Works in rivers and streams

4.4.1 Te Awa Kairangi/Hutt River

The Project requires some reshaping of the riverbed to enable construction of the new bridge. This involves riparian vegetation removal and recontouring of gravel to provide a suitable platform for construction vehicles to launch and crane/lift the bridge structure into place once the bridge piers have been constructed.

Approximately 2,000 m3 of bed material over a total area of approximately 1,000 m2 will be disturbed and recontoured to support construction of the bridge superstructure. This is expected to be largely in-situ beach material and little if any of this material will be from within the active channel (flowing water).

Recontouring of the bed to temporarily divert flowing water may also be required to allow construction works associated with river banks and the installation of piers to be undertaken in the dry. In-situ material will be recontoured and shaped into bunds to protect construction areas from flowing water.

Any areas of disturbed banks will be shaped and planted post construction with either natives, willows or a combination of both, as shown in the Landscape Concept Plans contained in Appendix G to provide bank stability and minimise scour and erosion.

4.4.2 Unnamed tributary

Temporary diversion of flow from the unnamed tributary will be required to trench the pipeline under the bed. Flow will be over-pumped and returned to the tributary downstream of the disturbance.

Post pipeline installation a permanent weir/ford structure will be constructed to provide ongoing access across the tributary for maintenance and repairs to the Kaitoke Main pipeline on the western bank. The design of the weir/ford will be confirmed through detailed design but the applicant confirms the structure will be designed to maintain existing flows and support fish passage.

4.5 Earthworks and vegetation removal

4.5.1 Earthworks

Earthworks including excavation and filling, reuse of on-site material, removal of waste material and importing of angular aggregate material to stabilise disturbed surfaces is proposed across the Project.

Earthworks are associated with ground improvement works, trenching and laying of underground sections of pipeline and the construction of the pipe bridge and access embankments. The majority of earthworks will be cut to fill with the excavated material used to backfill excavations or re-spread on-site. Excavated material will be stockpiled nearby for re-use across the Project as required, it is estimated stockpiles will have a maximum height of 2.5 m. Any excess cut that cannot be re-used on site will be disposed of off-site, this material is expected to be a relatively small proportion of the earthworks required.

The bulk earthworks (including both cut and fill) totals are still to be confirmed but are expected to be in the order of:


Activity Approx volume (m3) Approx area (m2)

Western bank (pipeline alignment)36 16,000 14,000

Bridge construction (including ground improvement works, piers and embankments)

56,050 33,800

Temporary construction structure (in river) 2,000 1,000

Eastern Bank pipeline and chamber 1,500 1,500

4.5.2 Vegetation removal

Approximately 17,800 m2 (1.78 ha) of indigenous or mixed native and exotic vegetation within the existing river corridor will need to be removed to enable construction of the pipe bridge, and further areas of vegetation will be cleared to construct the new pipeline within Manor Park Golf Course. The extent of the potential vegetation disturbance is shown in Landscape Concept Plans contained in Appendix G and the ecological and amenity values of these vegetation communities are discussed in sections 9.3.3.1 and 9.5.3.3 of this AEE.

4.6 Network utilities

4.6.1 Services

There are several services that the pipeline will cross during construction. Due to the size of the pipe, creating additional bends to fit under or over services will add significant time and cost to the construction of the pipeline. For this reason, where possible, services will be relocated when they are in the path of the proposed pipe alignment.

In cases where services are unable to be relocated (i.e. high pressure gas mains), the new pipe will be constructed under or over the service. In these cases, strict supervision will be carried out and appropriate safety procedures followed.

The temporary changes and relocation of network utilities include:

– Electricity and gas distribution including the relocation of high and low voltage power cables

– Temporary relocation of the 33 kV overhead lines

– Fibre optic communication cables and telephone lines

4.6.2 Roads and rail

As described in section 4.2.1 above, a section of the 1993 pipe design was constructed underneath SH 2 and the KiwiRail corridor and capped at both ends. This existing section will provide a link between the new Kaitoke Main pipeline and the existing main on the western side of SH 2.

As the cross-connection is located within and under the carriageway of SH 2 and the rail corridor, careful planning is required during construction to minimise disruption when connecting the link to both the new and existing pipelines.

36 Includes worst-case scenario footprint of swale for scour water discharge


5 Construction Methodology 5.1 Introduction

This section provides an outline of an indicative construction methodology to inform the assessment of environmental effects. It provides a broad overview of the likely construction methodology for the Project and provides details of the main construction elements that are likely to be undertaken. The approach outlined is based on the experience the two ECI (Early Contractor Involvement) contractors have in developing and constructing projects of a similar scale locally and throughout New Zealand.

The information provided in this section is indicative only and is intended to provide sufficient detail of the proposed construction activities to confirm the Project can be constructed, to enable an assessment of the potential construction related effects on the environment and to identify any necessary measures to avoid, remedy or mitigate those effects.

Construction of the Project will be influenced by a number of factors, including:

– The detailed design of the Project, which will occur concurrently to the consideration of resource consents, will be confirmed once consents have been granted;

– The construction timing, staging, and duration;

– The procurement method adopted for construction of the Project; and

– Technological advances in construction techniques and methodologies.

The applicant seeks flexibility in final design and construction methods to accommodate these factors, while ensuring that adverse effects on the environment are appropriately remedied or mitigated.

Once the contract(s) for the Project have been awarded and a contractor (or contractors) are in place, the construction methodology will be further refined and developed. This refinement will be undertaken in compliance with conditions of the resource consents which will be in place to manage the effects of the construction activities.

5.2 Development of the construction methodology

The construction methodology and activities outlined in this section were developed through an iterative process that involved several rounds of reviews with two contractors and their supporting technical specialists (ECI). The intention was to consider the programme implications and potential adverse effects of various construction options to achieve a methodology that, as far as practicable, avoids, or otherwise minimises, potential adverse effects, while being operationally efficient. This included consideration of the following:

– The potential location and extent of construction compounds, bridge construction yards and construction haul roads, with the intent being to minimise disturbance and vegetation clearance in sensitive environmental areas;

– The construction methodology for the bridge, with the intent being to minimise disturbance of the river bed and banks;

– Construction programme and timing of particular activities, to take advantage of seasonal weather conditions;

– Best practice construction guidelines and consent authority standards, relevant to the avoidance and minimisation of adverse effects on the environment;

– Practical implementation, access requirements, safety and cost considerations, and potential for staging;


– The use of well-established construction techniques while not precluding methods to maximise the opportunity for contractor innovations; and

– Opportunity to reuse excavated material on site to minimise off-site disposal.

5.3 Indicative construction programme

It has been assumed that construction of the Project will start in 2022 and take approximately two years to complete. Enabling works may be undertaken and the construction programme anticipates this. For example, some vegetation clearance, site establishment and relocation of utilities may be done in advance of the main construction period.

The indicative construction programme is based on the following typical sequence of works:

– Enabling works (vegetation clearance as necessary, services relocation, site establishment);

– Main construction works including:

• Ground improvements;

• Earthworks;

• River works;

• Structures;

• Pavements and surfacing; and

– Completion works (reinstatement/landscaping).

The specific staging and phasing of the work will be dependent on the method of procurement and contractor expertise, the availability of contractors and availability of other resources such as materials and construction equipment.

While some elements of the Project will be undertaken concurrently (such as pipe bridge and pipeline construction), it will be necessary to construct many elements sequentially to manage flood risk, optimise materials and minimise disruption, in particular to the Eastern Hutt Road and SH 2 freight and commuter traffic.

5.4 General philosophy

The Project will involve a range of typical construction activities including earthworks, piling, the placement of structures, and heavy vehicle movements, with associated noise and dust emissions.

The construction phase of the Project will seek to minimise disruption to the river bed, adjacent properties and the wider community. This is to be achieved through measures including offsite construction of structural elements (e.g. bridge members and arch components), use of proprietary products, and standardised designs. It is intended that as much of the Project is built off site as is possible. This will allow for construction elements which may have adverse environmental effects, to occur off site in controlled environments, and be brought into the Project area as and when required. This will minimise disruption, allow for swift assembly and installation and reduce overall potential adverse effects from the Project construction phase.

5.5 Enabling works

Prior to the commencement of the main construction activities it is anticipated there will be works undertaken that will facilitate efficient construction. These works are likely to be:

– Further detailed site investigations, including geotechnical investigations to confirm the ground conditions at pier locations and the location of existing services and pre-vegetation clearance checks;


– Site establishment activities, including establishing site access points, haul roads, construction yards, site offices, worker facilities and fencing;

– Establishment of temporary routes/detours for pedestrians and cyclists;

– Establishing environmental mitigation measures (e.g. erosion and sediment controls);

– Vegetation trimming and clearance, and

– Protecting and/or relocating existing network utilities

Site establishment work will include setting up site compounds and temporary fencing and providing locations for the storage of materials and working areas for cranes. This is expected to consist of portacom buildings and storage containers, site ablutions, laydown and storage areas and security fencing on both sides of the river. Fencing will be installed generally along the construction site boundary with entry and exit points to the Project site on both sides of the river. Fencing will be maintained so all visitors and truck movements to the site are controlled and monitored. Any topsoil stripped during establishment of the site compounds will be stock-piled for re-use during landscaping works (with appropriate erosion and sediment controls).

Working areas adjacent to the pipe bridge location will be required for a crane to lift the new bridge sections into place. This will require trimming and felling of vegetation on the eastern and western banks of Hutt River/Te Awa Kairangi. Ground improvement works requiring excavation of unsuitable in-situ material and replacement with imported hardfill will be required at the crane platforms and within areas of the river bank to provide access to the river.

Bunds will be constructed around the site offices/construction yard and laydown areas to provide protection from flooding during the construction period. The bund will be to the level of the 1 in 100 year flood with an additional 0.5 m freeboard and created from excavated materials and stabilised.

Longer term traffic management measures such as re-routing of pedestrian and cycle routes within the river corridor will also be implemented as part of the enabling works phase.

5.5.1.1 Protection and relocation of existing network utilities

Existing network utilities affected by the construction of the Project will need to be maintained, protected or relocated.

The applicant has a number of existing memoranda of understanding with network utility providers for similar works. Initial discussions have been undertaken with some network utility operators regarding the management of their assets during construction. Network utilities will be protected or relocated to the relevant provider's standards. Protection or relocation of existing utilities will generally occur prior to (as enabling works) or in conjunction with the main construction phase of the Project. The scope and timing of the necessary utility relocation and protection works will be developed and agreed between the applicant and network utility operators to enable continued operation, to mitigate any safety hazards and provide cost efficiency for the required works.

During the subsequent detailed design phase, construction methodologies will be developed in consultation with each network utility operator to manage effects of construction on specific network utilities.

5.6 Main construction works

5.6.1 Public access to recreational areas

During construction works it is probable, for the safety of the public, that the recreational areas and tracks within the river corridor will be closed to public access. The period of time that access will be restricted will be


equivalent to the duration of the construction period plus any re-instatement works requiring heavy plant or machinery.

Where possible, temporary access tracks will be provided through the work areas, however this will depend largely on the contractor’s final construction methodology and the ability for the public to safely access these temporary tracks.

5.6.2 Pipe bridge construction

The following construction sequence for the proposed pipe bridge is envisaged, as detailed below:

5.6.2.1 Foundation/pier construction

For bridge approach embankments, mechanically stabilised earth will be used for the ramps and abutment foundations. The abutment beams will be formed and poured on-site.

A steel casing will be driven into the ground and the piling rig will bore the pile or alternatively the pile will be driven into the ground, with any material removed disposed of or re-used on-site. Drilling fluid comprising of bentonite or polymer compounds may be required. Piling specific controls will be established for this phase. This is likely to include dirty water diversions and silt fencing to contain sediment laden run-off. A dewatering system may be established if deemed to be required.

A reinforcing cage will be lifted into the pile and the pile will be filled with concrete using a concrete pump. The pile will then be trimmed to the required height. Any cement laden water will be pumped into tanks or removed by vacuum truck.

Following construction of the pile the pier head (or cap) will be constructed. Reinforcing, falsework and formwork is installed, concrete is poured and then stripped. The formwork is then removed.

This process will be repeated for each pier.

Construction of the piers is expected to take approximately 6 months to complete.

5.6.2.2 Bridge superstructure

Structural steel sections will be manufactured off-site and delivered to the site for assembly. The proposed assembly site for main span of the bridge (network arch section) fabrication is within the area abutting Eastern Hutt Road, in council reserve land adjacent to the river. Once assembled, cranes on each side of the river will be used to lift the bridge into place on the piers. The smaller truss bridges will be installed in-situ on the eastern and western banks after the arch structure is in place. After the superstructure comprising the arch structure and truss bridges is in place the pre-cast deck panels will be installed progressively from each side of the river.

A temporary crossing structure, such as a causeway or similar platform of pre-cast panels to support bridge construction will be installed within the bed of the river (refer section 5.6.4 below). If temporary piers are required to support the superstructure during construction these will be constructed off the temporary crossing structure (but do not require excavation of the bed).

Bridge superstructure construction is expected to take approximately 5 months to complete.

5.6.3 Pipeline

5.6.3.1 Pipeline on bridge

The section of the pipe on the bridge will be progressively installed along the bridge. A small Hi-Ab or similar equipment will be used to install the pipe brackets and pipe sections. This will involve carrying the pipe sections


out onto the bridge and lifting them into place. The pipe section will then be welded in place. The buried sections of pipeline on the bridge approaches will be connected to the bridge with flexible joints once the bridge pipe section is complete.

5.6.3.2 Underground sections of pipeline

Vegetation clearance will be undertaken along the pipeline corridor and erosion and sediment controls will be installed. This is expected to include silt fencing and dirty and clean water diversions. The pipeline will be installed in 12 metre sections. Small temporary pipes will be used to convey overland flow across and under work sites if required.

Flow will be temporarily diverted during excavation to install the section of pipeline under the unnamed stream. Following pipe installation, the trench will be backfilled, and the ford/weir structure will be constructed to provide permanent access over this section of stream. The flow will be reinstated over the weir/ford post its construction.

A 12 m wide construction corridor will be used in most cases to allow sufficient horizontal clearance from the top of the trench for machinery to safely pass however it is anticipated that this can be reduced to 7 m in locations of ecological sensitivity such as through the stand of Māhoe and across the unnamed tributary. The total area of disturbed land for the pipeline corridor is not expected to exceed approximately 10,000 m2.

The trench for the pipeline will be excavated in 12 m sections, with spoil trucked to nearby stockpiles. Excess spoil that is not used for reinstatement will be reshaped and left onsite. Bedding will be installed in the base of the trench and the pipe installed. The pipe will be joined and welded before backfilling to finished level.

Dewatering will be required during excavation of the pipe trench. Groundwater encountered will be pumped out of the trench and treated to the appropriate standard in a containment device (container or similar) before being discharged directly to the river.

The final cut‐ins at the cross-connection under the rail corridor and the western side of SH 2 to liven the pipeline will occur once the new pipeline section has been tested.

Construction of the pipeline through Manor Park Golf Course will take approximately 6 months to complete. The cut‐ins at the cross-connection will take a further two weeks to complete.

5.6.3.3 Reinstatement

Reinstatement will take place progressively as the pipeline is installed and areas are completed. In particular, along the pipeline corridor within Manor Park Golf Course, the grassed areas and unsealed tracks will be progressively reinstated. Around the bridge structure the embankment approaches will be constructed with structural fill, then topsoiled with topsoil from the onsite stockpiles ready for planting. other areas that have been disturbed as a result of pipeline installation will be landscaped in accordance with the Landscape Concept Plan contained in Appendix G.

Once the work requiring heavy machines is complete, the shared path sections on the bridge approaches will be poured. The site offices, car‐parking and storage areas will be removed, and the ground reinstated to its original state.

Erosion and sediment controls will be progressively removed as earthworked areas are determined to be stabilised. The site fencing will be removed after all ESC devices have been decommissioned and/or removed.

5.6.4 Temporary construction structure

A causeway or platform, with a base layer of site won river gravels, may be constructed within the river channel to support construction of the pipe bridge. The structure may include a temporary pier which would be


embedded into the platform (not the river bed) and would support the bridge deck during the construction of the network arch superstructure. The structure would be approximately 20 m wide, with a platform height approximately 1 m above river level and would be allowed to overtop and be washed out during flood events. The structure would remain in place until the bridge superstructure is complete, a period of up to 20 weeks.

5.6.5 Scour and erosion protection

Scour and erosion protection works include vegetative planting or rock riprap. These measures will be installed progressively throughout the Project as exposed faces are completed to provide either immediate protection (riprap) or to facilitate vegetative protection as early as possible.

Riprap protection comprises a layer of geofabric placed on profiled in-situ material, upon which is placed a bedding layer to protect the fabric, upon which are placed the riprap rocks.

The riprap will be constructed from the riverbank and be undertaken in no to low flow conditions. This work will be undertaken in either an up or downstream direction. Placement of the bedding layer and riprap will be by large excavator potentially with a long reach or a grapple attachment for the careful interlocking placement of individual rocks.

Bedding and rock material will be transported to the relevant construction site by truck.

5.7 General construction aspects

5.7.1 Construction areas

As identified above, the Project will have one or more site compounds from which the construction works will be managed for the duration of the Project.

Final locations and areas required for the construction compounds and bridge construction will be confirmed at detailed design stage and outlined in the Construction Environmental Management Plan (CEMP), once a contractor has been appointed.

5.7.2 Erosion and sediment control

The scale of the Project will require the disturbance of a large area of land on both sides of Te Awa Kairangi/Hutt River. An overriding principle for the Project has been to minimise disturbance of the river and the amount of construction-related sediment in the river and associated downstream catchment.

A key erosion and sediment control (ESC) principle will be to minimise the area and length of time that particular areas of ground are open or the riverbed is disturbed, through staging and sequencing of works and progressively stabilising disturbed areas to reduce the potential for erosion and sediment generation to occur. This best practice approach will be used in conjunction with proven structural and non-structural control devices and methods for the land-based earthworks and in river works. The over-riding ESC principle is to undertake works in the dry as far as practicable, and this is expected to require temporary diversion of run-off around construction areas and temporary diversion of ground and surface water during construction.

Best practice erosion and sediment control measures will be implemented for the Project. The erosion and sediment controls will include:

– Clean water diversions

– Dirty water bunds

– Silt fencing

– Stabilised hardstand areas


– Dewatering treatment system

5.7.3 Water use requirements for construction

Water may be required for construction activities, such as dust suppression. No resource consents for water takes are sought at this time. The contractor will be required to obtain sufficient water supply for construction of the Project. The potential source or sources are not yet known, but may involve reuse of water collected on site or reticulated drinking water, as the Te Awa Kairangi/Hutt River catchment is fully allocated. If the contractor's chosen source requires resource consent they will be required to obtain the consent prior to the commencement of works.

5.7.4 Construction vehicle movements

Light vehicles used during construction will be predominantly crew cabs (utility vehicles or light trucks), light trucks, maintenance plant, Project management and construction observation vehicles (car or utility vehicle).

The majority of vehicle movements associated with construction will be truck and truck and trailer movements. These movements will be largely confined to off-road activities or within the construction area. Heavy vehicle movements on the local road network will be predominantly for bridge lifts, importation of aggregate and fill materials to site, plus delivery of pre-cast structures and building materials. Construction traffic access to the eastern side of the river will be off Eastern Hutt Road and access to the western side of the river will either be through Manor Park Golf Course or via an existing access point near the Fergusson Drive intersection with SH 2 (left turn only).

It is expected that over dimension and overweight loads will occur overnight or off-peak. This would be for the delivery and establishment of heavy equipment (such as large excavators and cranes) and large loads (e.g. bridge beams and components).

An indicative number of daily construction vehicle movements is outlined in Table 8 below.

Table 8 Indicative construction movements

Activity Average movements (per day)

Pipeline Construction

Light Vehicles 30

Truck 5

Truck & Trailer 10

Eastern Hutt Rd Access

Light Vehicles 20

Truck 5

Truck & Trailer 1

Fergusson Drive Access

Light Vehicles 30

Truck 5

Truck & Trailer 1

5.7.5 Traffic management

Construction of the project will require temporary traffic management (TTM) on both SH 2 and Eastern Hutt Road during certain periods of construction. This may include:


– Shoulder and lane closures;

– Temporary deviations;

– Road closures/detours;

– Site access arrangements including acceleration and deceleration lanes; and

– Temporary speed limits.

In many instances construction activities can be undertaken offline, with temporary traffic management only needed where construction of SH 2 pipeline tie-ins is required under live traffic, or to manage traffic during delivery of materials and launching of the bridge. Traffic management will also include re-routing of pedestrian and cycle routes around construction areas for the duration of construction. Temporary traffic management controls will be implemented in accordance with the standards in the Code of Practice for Temporary Traffic Management (COPTTM) to ensure that measures are put in place safely and that the impacts of construction traffic are minimised as much as practicable.

5.7.6 Hazardous substances and materials

Construction activities and site works will include a wide range of machinery and construction plant. The majority of this plant will be motorised and require a regular supply of fuels and oils. The machinery will require refuelling on- site, with any required fuel, oils and other lubricants stored within or adjacent to the construction areas.

The management of hazardous substances, including storage, handling, transport and disposal, will be subject to specific management practice and industry guidelines. These measures will be outlined in the CEMP and will minimise potential effects on health and safety from exposure to hazardous substances and the potential for adverse effects on the environment.


6 Statutory context 6.1 Introduction

The purpose of this section is to set out the statutory framework against which the Project must be assessed. Relevant statutory matters are set out, including the applicable RMA planning documents as well as matters under other relevant legislation. This section focuses particularly on those provisions of the RMA that are relevant to the application, including:

– Purpose and principles of the RMA (Part 2);

– Duties and restrictions (Part 3);

– Applications for resource consent (Part 6).

An assessment of the Project against the statutory framework is provided in section 11 of this AEE. In addition, this section identifies the statutory authorisations sought under the RMA for the Project. In summary, the applicant is seeking construction related resource consents, as set out below.

6.1.1 Resource consents

The applicant is seeking resource consents for construction related activities associated with the Project37 including:

– Land use consent to disturb the soil of contaminated land pursuant to the NES Soil under section 9(1) of the RMA;

– Land use consents for land disturbance activities under section 9(2) of the RMA;

– Land use consents for earthworks and activities associated with construction of the pipe bridge and installation of network utilities under section 9(3) of the RMA;

– Activities in, on, under or over the bed of lakes, rivers and streams under section 13 of the RMA;

– Diversion of water in rivers and groundwater under section 14 of the RMA; and

– Discharge of contaminants to land where it may enter water under section 15 of the RMA.

6.2 Resource Management Act

6.2.1 Purpose and principles (Part 2)

Section 104 of the RMA is expressed as being subject to Part 2 of the RMA. Part 2 of the RMA is comprised of sections 5 to 8 and outlines the purpose and principles of the RMA.

Section 5 sets out the purpose of the RMA, being to promote the sustainable management of natural and physical resources, and states:

“(2) In this Act, sustainable management means managing the use, development, and protection of natural and physical resources in a way, or at a rate, which enables people and communities to provide for their social, economic, and cultural well-being and for their health and safety while —

(a) sustaining the potential of natural and physical resources (excluding minerals) to meet the reasonably foreseeable needs of future generations; and

37 There are no consents required for the operation or maintenance of the project. Further assessment of operation and maintenance requirements can be found in Appendix J.


(b) safeguarding the life-supporting capacity of air, water, soil, and ecosystems; and

(c) avoiding, remedying, or mitigating any adverse effects of activities on the environment.”

Section 6 of the RMA sets out the matters of national importance that all persons exercising functions and powers under the RMA shall recognise and provide for. Subsections (a), (b), (c), (d), (e), and (h) are relevant for the Project. In summary, these matters relate to:

(a) the preservation of the natural character of the coastal environment (including the coastal marine area), wetlands, and lakes and rivers and their margins, and the protection of them from inappropriate subdivision, use, and development:

(b) the protection of outstanding natural features and landscapes from inappropriate subdivision, use, and development

(c) the protection of areas of significant indigenous vegetation and significant habitats of indigenous fauna:

(d) the maintenance and enhancement of public access to and along the coastal marine area, lakes, and rivers:

(e) the relationship of Māori and their culture and traditions with their ancestral lands, water, sites, waahi tapu, and other taonga:

(h) the management of significant risks from natural hazards.

Section 7 sets out other matters to which particular regard shall be had. Of relevance to the Project are subsections (a), (aa), (b), (c), (d), (f), (g), (h) and (i) as set out below.

(a) kaitiakitanga:

(aa)the ethic of stewardship

(b) the efficient use and development of natural and physical resources:

(c) the maintenance and enhancement of amenity values:

(d) intrinsic values of ecosystems:

(f) maintenance and enhancement of the quality of the environment:

(g) any finite characteristics of natural and physical resources:

(h) the protection of the habitat of trout and salmon38:

(i) the effects of climate change.

Section 8 requires all persons exercising functions and powers under the RMA to take into account the principles of the Treaty of Waitangi (Te Tiriti o Waitangi).

6.2.2 Duties and restrictions (Part 3)

Part 3 of the RMA sets out a number of restrictions on the use of resources (including land and water), and on activities that impact on resources (such as the discharge of contaminants).

38 Salmon and the habitat of salmon are not relevant to the Project


Section 9 of the RMA imposes restrictions on the use of land. The Project will include land disturbance activities controlled under section 9(1) and the NES Soil and section 9(2) of the RMA related to earthworks which contravene regional rules, and numerous activities that require land use consent under district plan rules (section 9(3) of the RMA).

Section 13 of the RMA imposes restrictions on activities in, on, under and over the beds of lakes and rivers. Te Awa Kairangi/Hutt River traverses the Project area and it, as well as an unnamed tributary, will be affected by structures as part of the Project, through the installation of the new pipe bridge and maintenance access for the pipeline. The Project also requires temporary reshaping of the riverbed to construct a suitable access for construction equipment during construction and assembly of the pipe bridge.

Section 14 of the RMA relates to any take, use, damming or diversion of water. The Project will require temporary and permanent diversion of Te Awa Kairangi/Hutt River in association with reshaping of the river channel during construction and permanent diversion of floodwaters from Te Awa Kairangi/Hutt River due to permanent structures in the river and floodplain. There will be temporary diversion of water associated with works within and under the bed of the unnamed tributary. There will also be ground water diversion in the form of dewatering associated with construction of the Project.

Section 15 of the RMA restricts discharges into air, or into or onto land or water. The Project will involve discharges to land and water during construction, and maintenance of the pipeline in future39.

The specific resource consents and the relevant plan rules requiring consent are set out in section 6.9 below.

6.2.3 Resource consents

As the consent authority for the regional consent applications, GWRC must consider applications for resource consents under sections 104 to 107 of the RMA and may impose conditions under sections 108 and 108AA if it chooses to grant consent.

As the consent authorities for the district consent applications HCC and UHCC must consider applications for resource consents under section 104 of the RMA and may impose conditions under sections 108 and 108AA if they choose to grant consent.

6.2.4 Matters for consideration

As required by section 104, consent authorities considering applications for resource consent must, subject to Part 2, have regard to the following matters as assessed in this AEE. Table 9 below sets out the Section 104 requirements.

Table 9 Section 104 requirements

Section 104 requirement AEE reference

(1)(a) Actual and potential effects on the environment of allowing the activity

Section 9: Assessment of effects on the environment and the technical assessment reports in Appendix C to Appendix H of this Application

(1)(ab) Measures proposed for the purpose of ensuring positive effects on the environment to offset or compensate for any potential adverse effects

Section 9: Assessment of effects on the environment Section 10: Measures to manage effects on the environment

(1)(b) Relevant provisions of national and/or regional policy statements, national

Section 11: Statutory assessment

39 Although discharges of scour water are required during maintenance, these discharges are assessed as a permitted activity as outlined in Appendix J.


Section 104 requirement AEE reference

environmental standards, plans and other regulations

(1)(c) Other matters that are considered to be relevant and reasonably necessary to determine the application

Section 11: Statutory assessment

Section 105 of the RMA sets out further matters that must be considered in relation to the consents sought for the discharge of water and contaminants (stormwater and sediment) during construction and discharges of potable water during the ongoing operation of the Project. The matters identified in section 105 of the RMA are assessed in sections 9 and 11 of this AEE, which demonstrate how the requirements of section 105 are met.

Relevant policy statements and plans are identified in section 6.3 below. An assessment against these provisions is provided in section 11 of this AEE.

In addition, there is a range of 'other matters' that must be considered, which can include matters outside the RMA, including non-statutory policy documents. A brief description of other matters relevant to the Project is outlined in sections 6.4 to 6.6 below. An assessment against other relevant matters is provided in section 11 of this AEE.

6.2.4.1 Restrictions on the power to grant consent

Section 107(1) of the RMA restricts the power to grant resource consent to discharge a contaminant or water where that discharge is likely, after reasonable mixing, to give rise to any of a number of specified types of adverse effects. This restriction is subject to the exceptions listed at section 107(2), including where there are exceptional circumstances, or where the discharge is of a temporary nature.

A detailed assessment against section 107(1) is contained in section 11 of this AEE.

6.3 Plans and policy documents

The national, regional and district planning and policy documents relevant to the Project (prepared in accordance with the RMA) are listed below.

6.3.1 National Policy Statements

6.3.1.1 National Policy Statement for Freshwater Management 2020 (NPSFM)

The revised NPSFM came into effect on 3 September 2020. It contains one overall objective and 15 policies. The policies relevant to the Project are summarised below:

– Te Mana o te Wai and involving tangata whenua in freshwater management (Policies 1 and 2);

– Integrated whole-of catchment management (Policy 3);

– Integration with New Zealand’s response to climate change (Policy 4);

– Implementation of a National Objectives Framework to ensure that the health and well-being of degraded water bodies and freshwater ecosystems is improved, and for all others is either maintained or improved (Policy 5);

– No loss of extent of inland wetlands and protection of their values (Policy 6);

– Avoidance of the loss of river extent and values to the extent practicable (Policy 7);

– Protection of significant values of outstanding water bodies (Policy 8);

– Protection of the habitats of indigenous freshwater species (Policy 9);

– Protection of the habitat of trout and salmon (Policy 10);


– Efficient use and allocation of freshwater (Policy 11);

– Achievement of the national target (as set out in Appendix 3) for water quality (Policy 12);

– Monitoring and reporting (Policies 13 and 14); and

– Enabling communities to provide for their social, economic, and cultural well-being (Policy 15).

These provisions will be taken into consideration when assessing the proposal under the PNRP. An assessment of the Project in relation to the NPSFM provisions is provided in section 11 of this AEE.

6.3.2 National Environmental Standards

6.3.2.1 Resource Management (National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health) Regulations 2011

The NES Soil regulates the use of land that is or may be contaminated, if one of the five specified activities is proposed on that land. In doing so, the NES Soil establishes a nationally consistent set of soil contaminant values for 12 priority contaminants, across five standard land use scenarios (rural residential, residential, high density residential, recreational and commercial/industrial), and a methodology for establishing the applicable standards for contaminants of concern that are not priority contaminants.

The NES Soil applies to sampling and disturbing the soil on any piece of land identified as meeting one of the following criteria:

– An activity or industry described in the Hazardous Activities and Industries List (HAIL) is being undertaken on it;

– An activity or industry described in the HAIL has been undertaken on it; or

– It is more likely than not that an activity or industry described in the HAIL is being or has been undertaken on it.

Rules in a district plan must be prepared in accordance with regulations in national environmental standards including the NES Soil, otherwise the regulations take priority.

The potential effects of land contamination are addressed in section 9.4 of this AEE, which concludes that there is land within the Project footprint where it is known that HAIL activities are likely to be currently, or are more than likely to have been undertaken. However, WWL commissioned a detailed site investigation which demonstrates that contaminants found in or on the land within the Project footprint are at or below background concentrations. As a result, the NES Soil should not apply to the Project40 and resource consent is not strictly required.

However, an area of the pipeline alignment through Manor Park Golf Course has not been able to be sampled due to delays in the geotechnical programme. It is not expected that contaminants within this area will be any different to those in other areas of Manor Park Golf Course, but soil in this area has not been sampled and a conservative approach has been adopted. Accordingly, consent is sought from HCC to disturb the soil of contaminated land (within Manor Park) during construction as a controlled activity under regulation 9(1) of the NES Soil. This consent is pursuant to section 9(1) of the RMA, for an activity that is not allowed by a National Environmental Standard without a resource consent.

A detailed assessment of the proposal against the requirements of the NES Soil is provided in Appendix J of this AEE.

40 Regulation 5(9) NES Soil.


6.3.2.2 Resource Management (National Environmental Standards for Freshwater) Regulations 2020 (NESFW)

The NESFW came into effect on 3 September 2020. The regulations in the NESFW cover a variety of activities, including works within and adjacent to natural wetlands, and construction and alteration to structures such as culverts, weirs, fords and flap-gates within the bed of a river41.

No consents are required under the NESFW as it does not apply to this proposal for the reasons outlined below.

6.3.2.3 Wetlands

There is a potential wetland habitat adjacent to the Project area. This area will not be disturbed or affected in any way by Project works.

WWL commissioned an ecological assessment of this potential wetland (refer to Assessment of Ecological Effects in Appendix F) in order to determine whether the area was considered to be a ‘natural wetland’ as defined by the NESFW42. In summary, the assessment found this area does not fall within the scope of ‘natural wetland’ as defined by the NESFW (or the PNRP) due to the dominant cover of Yorkshire fog. In any case, this wetland area will not be affected by Project works as it falls within an area of indigenous vegetation identified for retention.

6.3.2.4 Works in rivers

The relevant activities which fall under the NESFW relevant to the Project include the potential construction of a temporary causeway in Te Awa Kairangi/Hutt River and placement and use of a weir/ford structure in the unnamed tributary.

Reclamation

‘Reclamation’ is defined to mean the manmade formation of permanent dry land, and includes the construction of any causeway into or onto any part of a bed of a river43. This only applies in the context of the formation of permanent dry land. Consequently, the temporary causeway required in Te Awa Kairangi for construction of the new bridge does not meet the definition of reclamation under the NESFW which reflects the definition of reclamation prescribed in the National Planning Standards44.

Proposed weir/ford

The Project includes installation of a weir or ford structure that will convey flow from the unnamed tributary over the underground pipeline and provide access across the tributary for maintenance activities. Installation of this ford/weir requires consideration under the NESFW because the tributary meets the definition of a river.

41 ‘River’ means a continually or intermittently flowing body of fresh water; and includes a stream and modified watercourse; but does not include any artificial watercourse (including an irrigation canal, water supply race, canal for the supply of water for electricity power generation, and farm drainage canal) (s2(1) RMA) 42 ‘Natural Wetland’ means: a wetland (as defined in the Act) that is not: (a) a wetland constructed by artificial means (unless it was constructed to offset impacts on, or restore, an existing or former natural wetland); or (b) a geothermal wetland; or (c) any area of improved pasture that, at the commencement date, is dominated by (that is more than 50% of) exotic pasture species and is subject to temporary rain derived water pooling (refer section 3.21 NPSFM) The NESFW defines “natural wetland” in the same way as NPSFM (see regulation 3 NESFW). 43 Regulation 3 NESFW defines ‘reclamation’ as in Chapter 14 of the National Planning Standards (2019). 44 ‘Reclamation’ means the manmade formation of permanent dry land by the positioning of material into or onto any part of a waterbody, bed of a lake or river or the coastal marine area, and: (a) includes the construction of any causeway; but (b) excludes the construction of natural hazard protection structures such as seawalls, breakwaters or groynes except where the purpose of those structures is to form dry land.


Regulation 72 of the NESFW contains conditions that set standards for weir design and Regulations 62, 64 and 67 require that prescribed information on weirs and fords be supplied to the regional council once the structure has been installed. This weir/ford will not affect fish passage as the stream does not provide habitat or connectivity for fish between the river and upstream catchment. The design of the weir/ford will be progressed as part of detailed design, however the applicant confirms the structure will be designed to meet NESFW fish passage requirements, to maintain passage in the (unlikely) event upstream passage becomes possible in future.

As the applicant confirms the structure will be constructed in accordance with all relevant conditions in Regulation 72 of the NESFW the activity is a permitted activity.

6.4 Regional Policy Statement for the Wellington Region

The Regional Policy Statement for the Wellington region (RPS) became operative on 24 April 2013. Relevant resource management issues are:

– 3.3 Energy, infrastructure and waste;

– 3.4 Freshwater (including public access);

– 3.5 Historic heritage;

– 3.6 Indigenous ecosystems;

– 3.7 Landscape;

– 3.8 Natural hazards; and

– 3.10 Resource management with tangata whenua.

An assessment of the Project in relation to the relevant sections of the RPS is provided in section 11 of this AEE.

6.5 Proposed Natural Resources Plan

The Proposed Natural Resources Plan (PNRP) was notified in July 2015. Hearings were held between 2015 and 2018 and decisions issued in July 2019. The plan is currently in the appeals stage – provisions that were not appealed or where the appeals have been resolved are deemed operative. Provisions with unresolved appeals are yet to be made operative and hence the operative provisions in the relevant regional plan remain relevant. The assessment in this AEE has been based on the PNRP as it stood at 1 July 2021.

A summary of specific consent triggers with respect to the PNRP rules is provided below in Table 10 and a full assessment of the applicable rules (including permitted activities) is set out in Appendix J.

A summary assessment of the Project in relation to the relevant objectives and policies of the PNRP is provided in section 11 of this AEE.

6.6 Operative Regional Plans

6.6.1 Operative Regional Freshwater Plan for the Wellington Region

As the PNRP is yet to be made fully operative, parts of the Regional Freshwater Plan (RFP) remain relevant to the Application. An assessment of the Project in relation to the relevant objectives and policies of the RFP is provided in section 11 of this AEE, and a full assessment of the applicable rules (including permitted activities) is set out in Appendix J.

The RFP was made operative on 17 December 1999 and was updated through six plan changes, the most recent of which took effect from 1 August 2014. A summary of specific consent triggers with respect to the RFP rules is provided below in Table 11.


6.7 City of Lower Hutt District Plan

The City of Lower Hutt District Plan (HCC DP) was made fully operative on 18 March 2004. The plan has been subject to a rolling review and HCC embarked on a comprehensive review of the District Plan in mid-2020. HCC’s current timeline suggests draft provisions will be released from mid-2021 with the plan not finalised and notified until mid-2022.

Objectives and policies relating to the following activities covered by the HCC DP are relevant to the Project:

– Bulk earthworks and land disturbance works

– Establishment of the pipe bridge across Te Awa Kairangi/Hutt River

– Construction, replacement, relocation, operation and maintenance of underground network utilities

– Construction of new structures in the Wellington Fault Special Study Area

– Ground improvement works

A summary of specific consent triggers with respect to the rules is provided below in Table 12 and a full assessment of the applicable rules in the HCC DP is set out in Appendix J.

6.8 Upper Hutt City Council District Plan

The Upper Hutt City Council District Plan (UHCC DP) was made fully operative in 2004. The most recent plan change became operative on 31 March 2021. UHCC embarked on a comprehensive review of the rural and residential chapters of the UHCC DP via Plan Change 52 in early-2020. Council’s current timeline suggests draft provisions for the plan change will not be notified for consultation until 2022.

Objectives and policies relating to the following activities covered by the District Plan are relevant to the Project:

– Bulk earthworks and land disturbance works

– Establishment of the pipe bridge across Te Awa Kairangi/Hutt River

– Construction, replacement, relocation, operation and maintenance of underground network utilities

– Construction of new structures in the Wellington Fault hazard area and 1 in 100 year flood extent

– Ground improvement works

A summary of specific consent triggers with respect to the rules is provided below in Table 13 and a full assessment of the applicable rules in the UHCC DP is set out in Appendix J.

6.9 Activities requiring resource consent

All activities that require consent under the regional and district plans are set out below.

All resource consents for the construction of the Project are being sought as part of this application. If, after detailed design is complete, further or different consents are required, these will be sought at that time.


6.9.1 Consents sought for construction activities

Table 10 PNRP consents sought - Construction

RMA consent Activity/scope of application Rule reference Activity Status

Land use (s.9(2)) – earthworks and vegetation clearance

Earthworks45 undertaken across the Project, including bridge abutment and piling construction, construction areas, access and haul roads which are greater than 3,000 m2 per property in any 12 month period. Vegetation clearance within 5 m of a surface water body.

R101: Earthworks and vegetation clearance

Discretionary Activity

Land use (s.13) – new river crossing structures in, on, under or over the bed of the river

New pipe bridge across Te Awa Kairangi/Hutt River with piers constructed within the riverbed, including temporary crossing structures required for construction, where the general conditions cannot be complied with:

• The catchment area above the bridge and temporary structures exceeds 50 ha

• The area of the bridges and temporary structures within the bed of the river exceeds 20 m2

R129: All other activities in river and lake beds Discretionary Activity

Land use (s.13) new structures New structures (e.g. scour outlets and erosion protection structures) in the bed of a river where the general conditions cannot be complied with:

• The footprint of the structure exceeds 10 m2


Land use (s.13) – demolition and removal of structures in, on, under or over the bed of rivers

Demolition and removal of temporary structures required for construction activities and the removal of the existing pipeline affixed to Silverstream road bridge where the general conditions cannot be complied with:

• the activity disturbs greater than 10 m2 of bed


Land use (s.13) – beach recontouring Beach/river bed recontouring where:

• general conditions cannot be complied with as works will occur within areas of the bed covered by water

• excavation will exceed a depth of 1 m


Land use (s.13) – bed recontouring and excavation of the river bed

Bed recontouring and excavation and disturbance of the river bed not otherwise provided for by any rule in the PNRP.


45 Definition of earthworks in the PNRP excludes (amongst other matters) earthworks associated with: (d) the construction, repair, upgrade or maintenance of: (i) pipelines .



Land use (s.13) – trimming or removal of vegetation from the bed of any river or lake

Removal of vegetation from the bed of Te Awa Kairangi/Hutt River where the general conditions cannot be complied with.


Land use (s.13) – tracking across Te Awa Kairangi/Hutt River

Construction vehicle tracking across and through Te Awa Kairangi/Hutt River not otherwise provided for.


Water permit (s.14) – take and diversion of groundwater

Excavation and associated take and diversion (including discharge) of groundwater for dewatering from land identified in the HAIL associated with bridge construction. (Note: Dewatering activities associated with the trenching and installation of the replacement pipeline, including chambers and fittings, will be undertaken in accordance with the WWL global dewatering consent (WGN170366))

R140B: Dewatering Restricted Discretionary Activity

Water permit (s.14) – diverting water within or from a river

Diversion of water within or from Te Awa Kairangi/Hutt River due to construction of structures in the floodplain that will obstruct the flow of water from Te Awa Kairangi/Hutt River during flood.

R135: General rule for damming and diverting water Discretionary Activity

Water permit (s.14) – placing structures that obstruct the flow of water

All structures (both temporary and permanent) which require consent under Rule R129 that will obstruct the flow of water in Te Awa Kairangi/Hutt River. This also includes temporary diversion of water within Te Awa Kairangi/Hutt River associated with construction works.

R131: Damming or diverting water within or from rivers


Discharge permit (s.15) –discharge of sediment and contaminants from earthworks and vegetation clearance

The discharge of sediment into water or onto land where it may enter water from earthworks or vegetation clearance on land within 5 m of a waterbody The discharge of sediment laden water from an area of bulk earthworks greater than 3,000 m2

R101: Earthworks and vegetation clearance Discretionary Activity


Table 11 RFP consents sought - Construction


Land use (s.13) – new river crossing structures in, on, under or over the bed of the river

New pipe bridge across Te Awa Kairangi/Hutt River with piers constructed within the river bed, including temporary crossing structure(s) required for construction, where:

• The length of the bridge and temporary crossing structure exceeds 6 m

• Structures are required in the river bed

• The disturbance of bed material exceeds 20 m3

Rule 49: All remaining uses of river and lake beds Discretionary Activity

Land use (s.13) new structures New structures (scour outlets and erosion protection structures) in the bed of a river not provided for by any other rule in the RFP.


Land use (s.13) – demolition and removal of structures in, on, under or over the bed of rivers and streams

Demolition of temporary structures required for construction activities and the removal of the existing pipeline affixed to Silverstream road bridge where:

• the activity disturbs greater than 20 m3 of bed material;

• Work is undertaken in flowing water during trout spawning (31 May – 31 August)


Land use (s.13) – bed recontouring and excavation of the river bed

Bed recontouring and excavation of the river bed not otherwise provided for by any rule in the RFP.


Land use (s.13) – trimming or removal of vegetation from the bed of any river or lake

Removal of vegetation from the bed of Te Awa Kairangi/Hutt River where the removal is not for flooding or erosion protection purposes or removal is undertaken in flowing water during trout spawning (31 May – 31 August)


Land use (s.13) – tracking across Te Awa Kairangi/Hutt River

Construction vehicle tracking across and through Te Awa Kairangi/Hutt River not otherwise provided for.


Land use (s.13) – structures and use of land in the floodway

The excavation and construction of structures and associated use of land within Te Awa Kairangi/Hutt River Floodway not associated with flood protection purposes where the structure obstructs the flow of water

Rule 48A: Uses of land within the Waiohine Floodway, the Lower Ruamahanga River Floodway, and the Hutt River Floodway

Restricted Discretionary Activity

Discharge permit (s.15) – stormwater discharge of sediment and contaminants from earthworks and vegetation clearance

The discharge of sediment laden water from an area of bulk earthworks greater than 3,000 m2 The discharge of contaminants that may enter water not otherwise provided for in the RFP. This includes discharges from contaminated land and dewatering discharges that cannot meet permitted activity conditions.

Rule 5: All remaining discharges to fresh water Discretionary Activity



Discharge permit (s.15) to discharge sediment during and as a result of works in watercourses (i.e. structures, bed disturbance etc described above)

The discharge of sediment associated with works in watercourses not otherwise provided for by the specific activity rules.



Table 12 Land use consents sought from HCC - Construction

Activity Activity/scope of the application Rule Reference Activity Status

Construction of new underground sections of pipeline

Where located outside of the rail corridor the permitted activity standards for earthworks associated with network utilities cannot be met.

Rule 13.3.1.15 All network utilities that are not otherwise listed as a permitted, controlled, restricted discretionary or non-complying activity.


Construction of the above ground sections of pipeline

Above ground sections of pipeline greater than 3.5 m above ground level and greater than 15 m2 in area.

Rule 13.3.1.11 Cabinets and other network utility structures not otherwise listed in this table that do not meet the permitted activity standards in Rule 13.3.1.9.


Construction of the new pipe bridge Construction of a new pipe bridge where associated earthworks exceed 1.5 m in height or depth and 100 m2 in area.

Rule 13.3.1.15 All network utilities that are not otherwise listed as a permitted, controlled, restricted discretionary or non-complying activity


Structures within the Wellington Fault Special Study Area

Any structure within the Wellington Fault Special Study Area that is not a permitted activity.

Rule 14H 2.1 All structures where the whole site or a portion of the site falls within the Wellington Fault Special Study Area


Earthworks not associated with establishment of a network utility

Earthworks associated with the construction of the earth embankments resulting in a change in ground level greater than 1.2 m and exceeding 50 m3.

Rule 14I 2.2 In all activity areas except Special Recreation Activity Area, Passive Recreation Activity Area, Hill Residential Activity Area, and the Landscape Protection Residential Activity Area, earthworks which fail to comply with any of the Permitted Activity Conditions.



Table 13 Land use consents required from UHCC - Construction

Activity Activity/scope of the application Rule Reference Activity Status

Construction of new underground sections of pipeline

Cabinets and other network utilities structures that do not meet the permitted activity standards

Rule 30.1 All network utilities that are not otherwise listed as a permitted, controlled, restricted discretionary or non-complying activity


Construction of the new pipe bridge Aerial crossings necessary for network utilities, located on or within existing bridges and structures or across watercourses that cannot meet permitted activity standards.

Rule 30.1 All network utilities that are not otherwise listed as a permitted, controlled, restricted discretionary or non-complying activity


Structures within the fault band hazard Any new structure to be erected within the fault band identified on the Planning Maps

Rule 33.1 Any new structure to be erected within the fault band identified on the Planning Maps


Structures within the flood hazard Buildings and structures to be erected within the 1% (1 in 100 year) flood extent of the Hutt River, as shown on the Planning Maps

Rule 33.1 Buildings and structures to be erected within the 1% (1 in 100 year) flood extent of the Hutt River, as shown on the Planning Maps


Earthworks not associated with establishment of a network utility

The site of the construction area is within the 1 in 100 year flood extent of the Hutt River.

Rule 23.1 Earthworks which do not meet the standards under rules 23.2 – 23.17 unless specifically identified as a Discretionary or Non-Complying Activity.



6.9.2 GWRC Flood Protection river maintenance consent

As noted in section 3.5.2 above, GWRC Flood Protection hold an existing consent which authorises river maintenance activities across a 28 km section of Te Awa Kairangi/Hutt River. The existing river maintenance consent WGN130264 is comprehensive in terms of the activities that it provides for. These are summarised as follows:

– Land use consent [32238]: River management activities in the bed and on the banks, berms and stopbanks of Te Awa Kairangi/Hutt River for flood protection, erosion control and public amenity purposes including:

• construction, maintenance, repair, replacement, extension, addition, alteration, demolition and removal of structures

• planting, maintenance and removal of vegetation

• re-contouring and mechanical ripping of the river bed

• constructing diversion channels

• shaping, re-contouring and repair of bank edges, berms and stopbanks

• clearance of flood debris

• operation of machinery in the river bed, entry and passage of the river bed

• maintenance of drains

• dredging

• construction of walkways, cycleways and associated structures including stormwater drainage, culverts, and footbridges; and

• excavation, disturbance and deposition of material.

– Water permit [34077]: To temporarily and permanently divert the flow of Te Awa Kairangi/Hutt River during and as a result of river management activities for flood protection, erosion control and public amenity purposes.

– Discharge permit [34034]: To discharge sediment and sediment laden stormwater into Te Awa Kairangi/Hutt River during, and as a result of, river management activities within and outside the river bed for flood protection, erosion control and public amenity purposes,

– Land use consent [34486]: To extract gravel from the bed and banks of Te Awa Kairangi/Hutt River using a combination of wet and dry methodologies.

The consent contains a very comprehensive description of river management activities which is consistent with all future GWRC Flood Protection operation and maintenance requirements for the section of the Te Awa Kairangi/Hutt River where the Project is located, being the Manor Park Reach: Pomare Rail Bridge to Silverstream Rail Bridges 46.

River maintenance activities include:

(f) development of vegetative bank protection, including tree planting, willow layering, cabling and tethering; and

(g) maintenance of vegetative works, including:

(i) additional planting;

46 As defined by the HRFMP


(ii) new layering of trees;

(iii) re-cabling of tethered willows;

(iv) removal of old trees; and

(v) trimming and mulching of trees;

Sitting behind this consent is the “Code of Practice” and “Environmental Monitoring Plan for River Management Activities” which together co-ordinate consistent implementation of all river management activities undertaken by GWRC Flood Protection.

Section 10 of the Code describes all river management methods that make up GWRC’s river management ‘toolbox’ including the measures to be taken to avoid or mitigate the potential adverse effects of the activity.

The Code can be amended (as per condition 11.1 of the consent). The consent also requires the following management plans to be prepared:

– Operational Management Plan – in relation to each reach of the river (consistent with the relevant HRFMP);

– Annual Work Plans (must be consistent with Operational Management Plan and sections 6, 10 and Appendix 7 of the Code); and

– Site specific effects management plans and monitoring (SSEMP) - required for activities listed in Condition 4.3 and 4.4 (high potential impact activities).

Other conditions also set key bottom lines for the following matters:

– managing bed levels

– minimization of disturbance of noise and amenity

– fish passage

– riparian vegetation (addresses high value riparian vegetation –means riparian vegetation within the consent area that is identified in the Operational Management Plan, the PNRP, by GWRC’s Key Native Ecosystems and Wetland Programmes, or by flood protection surveys as having significant indigenous biodiversity values)

– sediment release; and

– lizards and geckos.

Conditions also set out requirements for baseline monitoring and management, Kaitiaki monitoring, Ropu Kaitiaki (knowledge sharing) and annual reporting, amongst other matters.

6.9.2.1 Relevance to Project

Following completion of the Project, monitoring and any required modifications to the restoration planting or erosion protection works will be implemented under the construction consents for a period of 5 years.

Following this 5 year period, the applicant’s ongoing requirements will ‘fall away’ and the GW Flood Protection river maintenance consent will be the mechanism to provide for the maintenance of any planting and erosion protection structures within the river corridor. Any works undertaken under the river maintenance consent are assumed to be undertaken by GWRC Flood Protection.

An MoU between WWL and GWRC is currently being prepared which will set out the asset management responsibilities for the pipe bridge and pipeline post-construction.


6.9.3 Bundling of activities

Where there are a group of activities where the effects overlap, or where the activities are intrinsically linked (such that one activity could not occur without the others), it is appropriate for them to be considered holistically as a single bundle according to the most stringent activity status.

The resource consents for the Project are appropriately bundled together. The most restrictive activity status applies and therefore the Project is considered as a discretionary activity under both the regional and district plans.

6.9.4 Resource consent lapse period

Section 125(1)(a) of the RMA provides that a resource consent lapses, unless given effect to, five years after the date of commencement of the consent unless a date is specified in the consent. Pursuant to section 125(1), the applicant seeks an extended lapse period of 10 years for their respective resource consents.

The reasons for seeking 10-year lapse periods include:

– A requirement for flexibility in the event of another pandemic lock-down; and

– Potential delays if funding priorities change, or there are difficulties sourcing a contractor or components.

6.9.5 Consent duration

The applicant seeks resource consents with the following durations:

– Unlimited duration in respect of land use consents under section 9(2);

– Five (5) years from the date of commencement under sections 13, 14 and 15 of the RMA, in respect of consents required for construction activities; and

– Thirty-five (35) years from the date of commencement under sections 13 and 14 of the RMA in respect of consents required for permanent structures in the bed of a river.

6.10 Existing designations

There are no existing designations to authorise the works required to construct the Project.

The designations set out in section 3.2.2 are located immediately adjacent to the Project area. In order to undertake work on land where there is an existing designation in place, which would prevent or hinder a public work or project or work to which the designation relates, the written consent of the requiring authority is required under section 176(1)(b) RMA.

The works required to tie-in the proposed Kaitoke Main to the existing cross-connection under SH 2 and the KiwiRail corridor will require disruption to the operations of SH 2 and the rail network. The works are expected to require temporary lane closures and suspension of operations on the rail network at this location. As a result, these works will likely hinder the purpose of these designations.

Prior to construction commencing on land subject to existing designations, approval under section 176(1)(b) RMA will be required from KiwiRail and Waka Kotahi.

6.11 Statutory acknowledgements

A statutory acknowledgement is a formal recognition by the Crown of a particular cultural, spiritual, historic and traditional association that an Iwi has with a specific area. The statutory acknowledgements provided under Treaty Settlement legislation for areas within Lower Hutt are confirmed in the PNRP – Chapter 12 – Schedule D.

There are two statutory acknowledgements within the Project area:


– Port Nicholson Block (Taranaki Whānui ki Te Upoko o Te Ika) Claims Settlement Act 2009, which includes Te Awa Kairangi/Hutt River; and

– Ngāti Toa Rangatira Claims Settlement Act 2014, which includes Te Awa Kairangi/Hutt River.

6.12 Other legislative matters

This section provides a brief introduction to the other legislation that will be relevant in the delivery of the Project to provide context for other authorisations that are expected to be necessary for the Project. Any authorisations required under other legislation are not applied for as part of the current application package and the requirement for additional authorisations is stated for information only. The additional authorisations will be applied for at the appropriate phase of the Project.

6.12.1 Heritage New Zealand Pouhere Taonga Act 2014

The District Plans (HCC DP & UHCC DP) do not identify any Significant Archaeological Resource Sites within the Project area. The Archaeology Assessment concluded that there is no reasonable cause to suspect that heritage or archaeological sites will be disturbed during the proposed works. Therefore, it is considered that no authority is required under the Heritage NZ Pouhere Taonga Act 2014.

6.12.2 Wildlife Act 1953

The Wildlife Act 1953 addresses the protection and control of wild animals and birds and the management of game. The potential effects of the Project on protected species are discussed in section 9.3.3 of this AEE. An application will be made under the Wildlife Act for an authority to relocate protected species, including lizards, prior to commencing construction of the Project.

6.12.3 Utilities Access Act 2010

A Corridor Access Request (CAR) is a type of permit required by Road-Controlling Authorities and Waka Kotahi for excavation work, or other non-excavation activities, within a transport corridor. This is to comply with the National Code of Practice for Utility Operators’ Access to Transport Corridors and is a legislated requirement under the Utilities Access Act 2010.

Representatives of all utilities, local authorities, Waka Kotahi and KiwiRail have collaboratively developed the Code which followed several rounds of public consultation before being approved.

Excavation works will be required within both the road and rail corridor and a CAR will be required from Waka Kotahi and KiwiRail for these activities.

6.12.4 Legislation governing railway corridor access

KiwiRail’s operations are governed by the New Zealand Railways Corporation Act 1981 (NZRCA), the Railways Act 2005 and the State Owned Enterprises Act 1986. KiwiRail grants access rights to place utility structures in railway land in accordance with section 35 of the NZRCA. This access is granted through a Deed of Grant that sets out the responsibilities of each party and identifies the location where the Grantee is permitted to either cross rail land or have an asset on rail land. The applicant will need to obtain a Deed of Grant for access to the rail corridor and for the sections of pipeline trenched under the rail corridor approaching the existing cross-connection.

Section 75 of the Railways Act requires all Utility Operators to obtain the Railway Corridor Manager’s consent before entering the land. The applicant will be required to follow the CAR process when seeking to gain access to the rail corridor.


6.13 Activities considered to be otherwise consented

6.13.1 Existing consents

Table 14 sets out all known resource consents held by the applicant that may potentially be relied on to authorise certain aspects of the Project either during the investigation and construction phases, or for maintenance of the project works following completion.

Table 14 Existing consents

Consent holder/ No / Type Purpose Granted Expiry Comment

Wellington Water Limited (WWL) WGN170366

[34868] Water permit

To divert and take groundwater for the purpose of dewatering

13/10/17 13/10/37 The WWL global dewatering consent provides for dewatering to enable the maintenance, repair, upgrade and installation of stormwater, sewer and bulk water infrastructure. This consent will be used to manage dewatering activities associated with trenching and installation of the replacement pipeline.

[34869] Discharge permit

To discharge treated dewatering water to water and to land where it may enter water including the coastal marine area.

[34983] Land use

Land-use consent (bores) to; Install dewatering spears; Construct and maintain bores for geotechnical and groundwater sampling purposes; and Excavate trenches which intercept groundwater


7 Consideration of Alternatives 7.1 Introduction

Clause 6 of Schedule 4 to the RMA requires that assessments of environmental effects include “a description of any possible alternative locations or methods for undertaking the activity” if “it is likely that the activity will result in any significant adverse effect on the environment.” While the expert assessments do not suggest that effects on the environment will be significantly adverse, good practice for environmental impact assessment requires a consideration of alternative locations and methods as part of identifying and evaluating the effects associated with an activity.

In addition, particular provisions of the PNRP require no other practicable alternatives to be available to enable the activity to occur – such provisions include PNRP Policy P27.

This section describes the consideration of alternatives process carried out for the Project, both in determining the pipeline alignment and the design refinement of the proposed bridge structure, which both used an MCA process and also describes the alternative construction methodologies considered to construct the bridge, developed in collaboration with the ECI contractors.

The assessment of alternatives for the Project occurred in two stages:

– Alternative alignments and locations and the type of design solution; and

– Refinement of bridge design options and more detailed assessment of structural design alternatives for the crossing.

7.2 Project history and previous reports

In 1991 the Bulk Water Supply department of the Wellington Regional Council (now GWRC) proposed diversion of the Kaitoke Main to mitigate the adverse effects of a realignment of SH 2, and to address flooding and earthquake risks to the pipeline on the Silverstream road bridge. GWRC prepared a design for their proposed pipeline (colloquially referred to as ‘the 1993 design’). The route of the pipeline in the 1993 design consisted of the following:

– Started at the Kingsley Valve Chamber in Fergusson Drive

– Was installed through the rail embankment at the eastern end of the Silverstream rail bridge

– Was laid on the eastern side of Eastern Hutt Road between the rail bridge and Hutt Valley bulk sewer crossing (weir)

– Was laid on the western side of Eastern Hutt Road between the Hutt Valley bulk sewer crossing and a point approximately 1,000 m south of Fergusson Drive

– Was trenched and laid under Te Awa Kairangi/Hutt River

– Was laid in Manor Park Golf Course and across the rail corridor and SH 2 to connect to the existing pipeline

A short spur connection was constructed south of the Manor Park Clubhouse across the rail corridor and SH2, but other than this, the 1993 option did not progress further. The reason is unknown.

In 2015 MWH completed a pipeline condition assessment and replacement feasibility study which shortlisted five options for replacing the Kaitoke main and Kingsley pipelines47.

47 Silverstream Bridge Pipeline Condition Assessment and Realignment Options Feasibility Report, MWH, 2015


In 2016, GHD was engaged to assess the 1993 design in terms of constructability, practicality and seismic resilience of the alignment, and to prepare a preliminary design based on the 1993 design; or if the 1993 design was found to be unsatisfactory, to prepare a preliminary design based on a more practical route. Part of this process involved determining the actual location of the Wellington Fault, as opposed to the indicative location based on desktop assessment.

Geotechnical assessment determined the Fault was located to the south of the estimated location, on the northern (true right) bank of the river. This had a significant impact on the feasibility of the 1993 design, particularly with regard to resilience and repairability after a significant earthquake event, due to the 1993 design involving trenching and laying the pipeline under Te Awa Kaiangi/Hutt River. As a result, GHD undertook a broader options identification process. This process is summarised in the following sections.

7.3 Options Identification

The approach to identifying options entailed:

1. Collating existing alignment and design options considered in the 1993 design to re-align the pipe, and the 2015 feasibility study completed by MWH.

2. Undertaking a high level engineering assessment by GHD based on the most current survey information, liaison with subject matter experts and early contractor involvement (ECI) to determine construction, supply and logistical risks.

3. Engagement with potentially affected stakeholders (Manor Park Golf Course, NZ Transport Agency, GWRC Flood Protection, KiwiRail, Silverstream Retreat) to understand potential property impacts and to inform identification of options which would or could reduce potential impacts on their land. Whilst options were not discounted at this stage because of stakeholder input, impacts on private property and stakeholders this was reflected in the option scoring.

This process resulted in the identification of 20 different options, some of which were variations of an option (for example Option 15 was a variation of Option 14 and Option 19 was a variation of Option 18). The options described in Table 15 included shortlisted options from the 2015 MWH feasibility study. The ‘Do Nothing’ option was discounted because of the project drivers and the importance of the pipeline to the water supply for the Wellington region.

Table 15 Initial options

Option Description

1 1993 Design - Pipeline trenched and laid in Hutt River

2 1993 Design - Pipeline crosses Hutt River on a new pipe bridge

3 Strip of private land purchased so pipeline does not clash with sewer/gas. Trench and laid in river

4 Strip of private land purchased so pipeline does not clash with sewer/gas. Crosses river on new bridge

5 Pipeline on upstream side of existing road bridge and trench and laid in SH2

6 Pipeline on upstream side of bridge and trenched and laid in rail corridor

7 Pipeline on down-stream side of bridge and trenched and laid in SH2

8 Pipeline on down-stream side of bridge and trenched and laid in rail corridor

9 Pipeline on down-stream side of bridge and trenched and laid in golf course

10 Pipeline on separate pipe bridge and trenched and laid in golf course

11 Pipeline on separate pipe bridge and trenched and laid in rail corridor

12 Pipeline trenched and laid on western side of Eastern Hutt Road and under river upstream of bulk sewer weir, crossing sewer


Option Description

13 Pipeline trenched and laid on western side of Eastern Hutt Road and under river upstream of bulk sewer weir, parallel to SH2

14 Pipeline trenched and laid on western side of Eastern Hutt Road. Pipeline crosses river by pipe bridge

15 As per Option 14 except crossing is moved upstream and pipeline is trench and laid in rail corridor and not golf course

16 Pipe inserted in spare sewer duct. Pipeline trenched and laid in golf course

17 Pipeline trenched and laid on western side of eastern Hutt Road, crosses Hutt River by tunnel and trenched and laid in golf course

18 Pipeline trenched and laid on western side of eastern Hutt Road, crosses Hutt River by pipe bridge and trenched and laid in golf course

19 As per Option 18 but pipe crosses river through bored tunnel under the Hutt River to the south of Option 18

20 Do minimum - reline the existing pipe along the existing alignment

A further eight options (refer Table 16) were identified in October 2018 from a variety of sources, including GWRC Flood Protection and WWL. This list included an option to build a new water supply pipe on a new Silverstream bridge (Option 25). This option had originally been discounted because of the time lag between the need to replace the Kaitoke Main at Silverstream and replacement of the Silverstream road bridge. It was reinstated at the request of GWRC Flood Protection.

Table 16 Additional options

Option Description

21 Tunnel option under river, located downstream of Option 19 where offset between tunnel and fault exceeds 50 m. Option requires new crossing under SH 2 and rail corridor

22 Pipeline on separate bridge, parallel to and mirroring existing rail and road bridges. Pipe angled to cross perpendicular to fault, trenched and laid in golf course

23 Similar to Option 22. Pipe bridge on downstream side of rail bridge. Pipeline crosses river by pipe. Bridge pipeline trenched and laid parallel to the rail corridor

24 Pipeline laid in river as extension to the existing weir structure. Extension constructed on the upstream side of weir to extend life of the weir. Pipeline leaves river at weir on east side of the fault and crosses fault by aerial span. Option similar to bridge crossing, but only has one portion above ground

25 Pipeline constructed on the new road bridge. Pipeline laid in SH 2

26 Pipeline built on upstream side of existing rail bridge. Trenched and laid parallel to the rail corridor on true right of the river

27 Pipeline alignment is the same as Option 21 except pipeline is trenched and laid in the river

28 Pipeline alignment is the same as Option 21 and 27 except pipeline crosses river on new pipe bridge. Pipeline crosses the fault on land by way of a trench

7.4 Evaluation criteria and weightings

The evaluation criteria and weightings were developed in stages – firstly by the GHD technical specialists in workshops on 22 and 25 May 2018 and then reviewed and updated with the inclusion of feedback from the Landscape and Ecology technical specialists (6th and 24th September 2018). The criteria, weightings and scoring range were reviewed by Kensington Swan in April and July 2018.

The criteria and weightings reflect the objectives of the WWL project brief to GHD, which required a resilient design solution, and the requirements of Part 2 of the Resource Management Act 1991. A summary of the evaluation criteria and sub-criteria are provided below in Figure 13.


Figure 13 Evaluation criteria and sub criteria

7.4.1 Scoring Results

Each option received a total calculated score between 1 and 5 (refer Table 17 for scoring range and descriptions), with the highest performing option (using the original weighting) scoring 3.71 (Option 14) whilst the lowest performing option scoring 2.02 (Option 6). The individual option score was derived from the rating multiplied by the weighting. The scoring range was relatively narrow (only 1.69 points between the highest and lowest performing options). The results showed that there was no perfect option.

Table 17 Scoring range and descriptions

Criteria Description

5 The alignment option presents few difficulties, taking into account reasonable mitigation proposals. There may be significant benefits in relation to this aspect of the alignment.

4 The alignment option presents a minor area of difficulty, taking into account reasonable mitigation proposals. There may be some benefits in relation to this aspect of the alignment.

3 The alignment option presents some areas of reasonable difficulty. Effects cannot be completely avoided. Mitigation is not readily achievable at reasonable cost and there are few or no apparent benefits.

2 The alignment option includes extensive areas of difficulty in terms of the criterion being evaluated, which outweigh perceived benefits. Mitigation is not readily available.

1 The alignment option includes extreme difficulties in terms of achieving the Project on the basis of the criterion being evaluated.


The application of different weightings during sensitivity testing resulted in three different best performing options (Options 2, 14 and 18) (refer Table 18). In the original weighting scenario, Option 18 scored 3.59 so little different to Option 14. In the original weighting scenario Option 2 scored 3.42.

Table 18 Outcome of sensitivity testing

A - Original weighting B - Equal weightings C - Higher Enviro/cost focus

D - Project objectives only

Highest performing option

Option 14 Option 18 Option 2 Option 14

Lowest performing option

Option 6 Option 9 Option 26 Option 12

7.5 Option Shortlisting

Twenty-eight options were too many to take forward for consideration by stakeholders. The options were therefore shortlisted in a workshop attended by WWL and GHD on 9th October 2018. The options were narrowed down by assessing each option against its ability to meet the Project objectives. During this workshop, it was agreed that ‘Future Proofing – the ability to add additional infrastructure to a future pipe bridge’ was not a key Project objective.

Part of the shortlisting process involved re-confirming and re-wording the Project investment objectives. The revised Project investment objectives are presented below:

1. Functional - The new water supply infrastructure can continue to supply 100% of Porirua and Stokes Valley’s water, and 40% of Wellington’s water (the dependent population) from 2021, and have an asset life meeting or exceeding 100 years.

2. Resilient - The new water supply infrastructure is likely to remain in service after a 1 in 2,500 year earthquake event and 1 in 5,00048 year flood event.

3. Repairable – Where the new water supply infrastructure fails, the supply can be permanently or temporarily reinstated within 30 days (using equipment likely to be available in close proximity) to continue to deliver water.

4. Flood protection – Any new bridge structure across the Hutt River provides for a 2,800 cumec flood (which is larger than a 1 in 2,500 year return period flood) to pass.

A shortlist of six preferred options based on the above investment objectives was identified, as presented in Table 19.

Table 19 Shortlisted options

Option Description Comment

14 This option consists of a pipe bridge, near the existing road and rail bridges, built perpendicular to the fault.

Its geometry crossing the Wellington Fault line is better and hence more resilient than other options. The option has the potential to accommodate pedestrian and cycling linkages and utilities in the future.

48 The Resilience project objective was developed with Stakeholders in early 2018 and was based on the NZTA Bridge Manual 3rd Edition Amendment 0 (May 2013). This Bridge Manual required IL4 (Importance Level 4) structures to be designed for a 1 in 5000 year flood event. The Bridge Manual was later updated with Amendment 3, October 2018. IL4 structure are now required to be designed for a 1 in 2500 flood event. Structures at Silverstream will be designed to a minimum of the 1 in 2500 year flood event, in accordance with the most recent Bridge Manual standard. This modification in design standard has no material effect on the ability of the bridge to withstand a significant flood event.


Option Description Comment

18 This option consists of a pipe bridge, further south, and built perpendicular to the fault.

Option 18 meets the Project objectives and is constructable.

21 This option consists of a tunnel crossing the river south of Silverstream Retreat, and crosses the fault perpendicularly in land using trenching.

Option 21 is a tunnel and therefore requires no work in the riverbed due to construction methodology, which reduces health and safety risks during construction. It also passes under the river within the bedrock and therefore is not as vulnerable as the other two southern options to scour and flood risk. It is therefore an option which should be short-listed as it meets all criteria, and is constructable.

23 This option consists of a pipe bridge, near the existing road and rail bridges, parallel to the existing bridges but turning to cross the fault line at a right angle (perpendicularly).

Similar to Option 14 but is constructed on an angle and avoids Manor Park Golf Course greens and fairways. Option 23 meets the Project objectives and is constructable.

24 This option utilises space in the existing weir, with the pipe leaving the weir to cross the fault line on a short aerial span.

Option 24 would require structures in the river and therefore the long-term resilience is less certain than other options. Option 24 meets the investment objectives and is constructable.

25 This option involves construction of a new road bridge which would also accommodate the new pipe.

Uncertain timeframes for construction and concerns about cost and resilience of a new road bridge that might not meet required design standards for the pipeline. Do not recommend short-listing but include in list of options presented to stakeholders for confirmation of decision and reasoning

7.6 Multi Criteria Analysis Process

On 14 November 2018 GHD facilitated a workshop with key stakeholders WWL, GWRC Flood Protection and iwi representatives, the purpose of which was to identify the preferred option for replacement of the Kaitoke Main at Silverstream. The workshop format applied New Zealand Treasury guidelines for multi criteria assessments (MCA), and the Better Business Case model. This method encourages collaboration between stakeholders to develop clear, concise and evidence-based investment proposals. In summary the following steps were completed at the MCA workshop:

– Workshop participants confirmed the investment objectives.

– Workshop participants confirmed the assessment criteria (refer Table 20). However, as part of preparation for the workshop, the criteria were grouped under sub-headings and the criterion headings modified in some cases (for example ‘Future Proofing’ became ‘Ability to accommodate additional infrastructure’).

– During the workshop Morrie Love, representing Te Ati Awa, confirmed there were no specific cultural matters which would influence the choice of one short-listed option over another. As a result, all options were given a score of 5 for this criterion.

– During the workshop Sharyn Westlake (representing GWRC Flood Protection) provided additional detail about the Hutt River and in particular buffer zones where development cannot occur (the Erosion Zone). As a result, the Option 18 bridge would have to be longer than originally anticipated to avoid the Erosion Zone and, as a result, would result in the loss of a fairway at Manor Park Golf Course.

– The workshop participants ranked the six shortlisted options and identified why options should either be removed from consideration or be considered further. This process included reassessing the scores for each


evaluation criteria. This resulted in the removal of three options from the shortlist being Options 21, 24 and 2549.

– The number of short-listed options was reduced to three – Options 14, 18 and 23. These options were variations of a new utility bridge over the Hutt River. A new utility bridge performed the highest against the criteria of: function, resilience and repairability compared to other shortlisted options.

Table 20 Assessment criteria

Assessment Criteria

Environmental and Social Impacts

Landscape and visual effects Landscape, visual amenity

Natural processes Water quality and ecology, groundwater quality and quantity, flood risk

Social cultural and heritage Cultural, archaeological and built heritage, public access, land and property Consentability Notification, timeframes for consent, and third party approvals

Cost, constructability and operations

Constructability Alignment with existing infrastructure, health and safety considerations, ease of construction.

Cost Total cost, Kingsley Pipeline upgrade cost, contaminated land disposal cost.

Ability to accommodate additional infrastructure

The option provides for an additional pipeline and/or other infrastructure to be added in the future

Operational requirements Maintainability, access for maintenance

A new bridge also provided the flexibility to be placed in a location that preserved future land uses and mitigated increases in flood risk in accordance with the HRFMP. Having reduced the number of short-listed options to three – Options 14, 18 and 23, workshop participants identified Option 14 as the most preferred. Option 14 is shown in Figure 14 below. The area in green is the location of modified infrastructure and areas in red are zones where there are constructability or resilience risks.

49 Options 21, 24 and 25 were excluded because of concerns about land impact, cost and the reduction in resilience and ability to repair and maintain these options in the long term.


Figure 14 Option 14

Once a crossing of Te Awa Kairangi/Hutt River (Option 14) had been identified as the preferred design response, the design of the structure used to carry the pipe over the river needed to be confirmed. Design of the crossing (bridge) also followed an MCA process.

WWL specified the bridge design requirements; these included:

– 100 years design life;

– The ability to accommodate seismic loads relating to the effects caused by movement of the Wellington Fault during a design event (7.1 Mw earthquake based on a 500-770 year event);

– The Design Brief specified that the Kaitoke Main is required to have an Importance Level of 4 (IL4) as defined by AS/NZS 1170 (Structural Design)

– HRFMP requirements by placing the superstructure above the 2800 cumec flood level;

Preferred Option (14)

A pipeline trenched and laid on western side of Eastern Hutt Road, then the pipeline crosses river by pipe-bridge. The option was originally proposed by the landscape expert. It has better landscape and natural character outcomes than many of the other options as the new structure will be grouped and viewed alongside other bridge and weir structures. The location is also a balance between sufficient clearance and orientation away from the Wellington Fault for seismic resilience and allowing for flood protection maintenance and work in the Hutt River.


– Allowance for two pipes and additional services (ducts) and vehicle access on the bridge deck for maintenance.

To meet these requirements, seven bridge designs were developed, and their advantages / disadvantages identified and assessed by way of MCA:

– Option 1: Super Tee

– Option 2: Steel Plate Girders

– Option 3: Network Arch

– Option 4: Suspension Bridge

– Option 5: Cable stayed

– Option 6: Pipe suspended bridge

– Option 7: Warren Truss

The bridge structure assessment included the same criteria used to determine the preferred alignment with some additional considerations related to maintenance and inspection requirements and constructability and constraints on construction materials. Ultimately the MCA assessment confirmed a ‘network arch’ bridge structure as the preferred option (Option 3). In short, the network arch structure was preferred because it was the only structure that would enable construction to be completed wholly outside of the bed of the river and was the most resilient structure under seismic events.

Selection of the network arch as the preferred structure was reinforced after further assessment and consultation with both WWL and GWRC Flood Protection. The preliminary design concept of the network arch is shown below in Figure 15.

Figure 15 Network arch bridge preliminary design concept

7.6.1 Preferred design option

The preferred replacement of the pipeline was Option 14, a new aerial crossing of Te Awa Kairangi/Hutt River in an area of existing infrastructure, between the Silverstream rail bridge and the wastewater weir.

The preferred bridge structure was a tied network arch bridge that crosses both Te Awa Kairangi/Hutt River and the Wellington Fault at an angle which allows the new bridge and pipeline to articulate over the Fault when it moves. The network arch was assessed to be the most seismically resilient for the site specific parameters and the structure can span Te Awa Kairangi/Hutt River avoiding the need for significant in-river work and permanent structures in the active channel. The bridge can be designed to allow the HRFMP design flood event (2800 cumec) to pass whilst not increasing the flood risk in this location.


This bridge structure also provides a safe platform for maintenance of the pipeline, includes provision for future services to be added later and has the additional benefit of providing pedestrian and cyclist access across Te Awa Kairangi/Hutt River at Silverstream.

7.7 Alternative bridge construction methodologies

Alternative construction methodologies for the bridge are very limited due to the size of the network arch required to span both the Te Awa Kairangi/Hutt River and the Wellington Fault, being a 100 metre span between Piers 2 and 3. The resulting weight and size of the network arch structure means that there are limited alternatives available to the ECI contractors to construct the bridge.

Manufacturing of the structural steel sections will be undertaken off site in sections and then delivered to site for final assembly.

Lifting the assembled network arch onto the piers requires very large cranes to be located on both sides of the river, due to the weight and size of the structure. Temporary works are required in the Hutt River to construct a causeway and working platform from the eastern bank to enable a crane to lift the network arch and other bridge superstructure into place. This bridge construction methodology has been proposed by both ECI contractors as the most appropriate and efficient way to install the bridge superstructure. Due to the weight and size of the network arch, the cranes required will be some of the largest available in New Zealand and close to the limit of the crane lift capacity. Therefore due to size and weight of the network structure and construction equipment limitations, temporary works in the Hutt River are required to locate the crane in a position which enables the bridge to be lifted into place.

7.8 Conclusion

In summary, in selecting the options now proposed for the Project, the applicant has carried out a structured, transparent, and systematic process, which has taken into account a wide range of potential alternatives. The construction of the selected option (network arch) has been tested with the two ECI contractors, and temporary works in the Hutt River are required to enable cranes to have a working platform from which the bridge superstructure can be lifted in to place.


8 Engagement and consultation 8.1 Introduction

This section provides an overview of stakeholder, iwi and public engagement with respect to the Project. It addresses the purpose of engagement and consultation, summarises feedback including the tools and techniques implemented, the parties engaged and the engagement outcomes. This section then goes on to outline the common issues and themes raised by the stakeholders, iwi partners, the Upper Hutt community and the wider public.

8.2 Engagement approach

Engagement has been guided by the principles and core values of the Internal Association for Public Participation (IAP2) and the respective guidelines for best practice consultation under the RMA and the Local Government Act (2002)50.

8.2.1 Engagement purpose and objectives

The purpose of the engagement across all stages is to build trust and acceptance amongst iwi partners and stakeholders, as well as to inform, consult, and involve them so as to gain feedback on the Project. The process informed the options chosen, and the design refinements made as design progressed. The objectives of the engagement varied depending on the Project phase, and the desired outcomes of engagement during that phase. However, the overarching engagement objectives for the Project are as follows:

– To work collaboratively with Taranaki Whānui and Ngāti Toa

– To work collaboratively with key stakeholders and the community

– To build understanding of the Project and support for its implementation

– To ensure key community groups, leaders and the community at large are informed about the consent process and able to have a say.

– To increase community and stakeholder understanding that this is part of wider programme of regional water supply upgrades

8.2.2 Engagement register and previous engagement undertaken

An engagement register summarising the engagement undertaken to date is attached as Appendix K . This outlines the dates and parties which have previously been consulted regarding the Project. This engagement register is summarised below.

8.2.2.1 Iwi engagement

Preliminary Design

Mana whenua advice was taken, in particular from Taranaki Whānui regarding the history of the area and the uses of the Project area by mana whenua. Mana whenua also attended the MCA workshops to help to develop and provide input into the decision making process which resulted in the final alignment, as proposed.

50 GWRC - Greater Wellington Regional Council Significance and Engagement Policy (2019); HCC - Hutt City Council Significance and Engagement Policy (2018) and Hutt City Council Community Engagement and Consultation Guidelines (2020), Upper Hutt City Council Significance and Engagement Policy (2020).


Both Taranaki Whānui and Ngāti Toa Rangatira have been consulted regarding the on-going development of the Project. Conversations with Ngāti Toa have been previously facilitated by Wellington Water’s iwi liaison advisor Ms Maiora Dentice (no longer with Wellington Water as of late 2020) and have been primarily with Ms Naomi Solomon.

Ms Solomon, on behalf of Ngāti Toa, has previously advised that this Project is not a priority for Ngāti Toa but there are capacity issues in terms of resourcing to provide input into the Project (refer Appendix L). Since the initial response from Ngāti Toa received in October 2020, where Ngāti Toa indicated that the project was not high on their priority list and there was limited capacity to provide someone to advise on the Project, the applicant has made further attempts to obtain the feedback of Ngāti Toa and to provide a forum to discuss the Project with Ngāti Toa. At this time, no formal response from Ngāti Toa has been received since October 2020. Wellington Water Limited continues to make efforts to engage directly with Ngāti Toa about the Project and as part of WWL’s partnership agreement with Ngāti Toa will continue to do so throughout the processing of the application and during the detailed design and construction phases. As the resource consent application is to be publicly notified, Ngāti Toa will also be able to make a submission reflecting any concerns or opinions they have regarding the Project during the notification period of this consent application.

Taranaki Whānui have been involved through the MCA process and early design development. No concerns have been raised by Taranaki Whānui and a Position Statement (attached as Appendix L) has been prepared outlining the key principles for Taranaki Whānui and the framework for collaboration and input from Taranaki Whānui during the detailed design and construction phases.

Consultation with Taranaki Whānui has been with Kara Puketapu-Dentice (no longer with Taranaki Whānui as of mid-late 2020) and more recently with Kura Moeahu regarding the preparation of the Position Statement. Mr Morrie Love on behalf of Taranaki Whānui and Wellington Tenths Trust has also been previously consulted about the Project and provided input into the MCA process.

8.2.3 Key stakeholders

8.2.3.1 Neighbouring landowners

Manor Park Golf Course is the only neighbour of the site which is not a council entity. Notably, the land is currently owned by GWRC and Clearspan Property Assets Ltd (NZBN 9429033072470). The land is leased to the operator of Manor Park Golf Sanctuary (referred to in this report as Manor Park Golf Sanctuary)51. Manor Park Golf Sanctuary were consulted as part of the engagement strategy as the works would affect the usage and operation of the golf course. Furthermore, their approval was sought in relation to access to the golf course for ground investigations relating to contaminated land (golf greens) and geotechnical investigations. A site visit with the representatives of Manor Park Golf Course was undertaken on the 11th June 2021. This identified areas to avoid with respect to scour and air valve chambers and refined the number of chambers required through the golf course site.

8.2.3.2 GWRC Flood Protection

GWRC Flood Protection has played a key role in shaping the Project through the MCA process by providing the design constraints related to flood risk to be understood.

During the MCA process general design considerations and constraints were provided by GWRC Flood Protection, and workshops were undertaken in September of 2018 to develop alternatives which defined a number of alternative options that were considered during the MCA. Further advice was provided in November 2018 to

51 The lease is not registered on the title.


refine option maps and identify Erosion Zones and to understand how GWRC Flood Protection managed the river channel and its margins at this location. This resulted in the shifting of the bridge approximately 150 m further downstream to its current location.

During the more recent design development phase GWRC Flood Protection have been consulted to discuss matters relating to scour, bridge abutments, bridge design, flood levels and design height of the bridge deck. GWRC Flood Protection have also provided additional support when determining the most appropriate approach to flood modelling to be used for the effects assessments for the Project.

8.2.3.3 Forest and Bird

Forest and Bird have two separate branches which have been consulted as part of this project. On the true right bank of the river, the Lower Hutt branch of Forest and Bird (Forest and Bird LH) have been involved in the restoration of the river margins with native plantings, as well as monitoring and improving the habitat for native lizard species in the restoration site. The Lower Hutt branch has been consulted regarding the disturbance of their native plantings as a result of the proposal. Forest and Bird LH have been regularly informed of the Project footprint as more information about likely extents and effects have come to hand. Forest and Bird LH have provided additional advice on species that they would like to be retained or replanted on-site, as well as providing input into the preparation of the indicative Landscape Concept to reinstate the site after works are completed.

The true left bank of the river is overseen by the Upper Hutt branch of Forest and Bird. This group has conducted plantings along Hull Creek, to the south of the Project. This includes plantings on the eastern and western sides of Eastern Hutt Road. None of the plantings carried out by Upper Hutt Forest and Bird will be affected by the Project. Despite this, they were engaged in a community meeting in March of 2021. No feedback was received, or issues raised.

8.2.3.4 KiwiRail

The pipeline alignment for the Project will potentially affect the KiwiRail corridor to the north of the subject site. The preliminary designs for the railway infrastructure have been reviewed by KiwiRail as they have been developed, and KiwiRail has shared design standards and requirements to ensure that the preliminary design will be consistent with KiwiRail requirements. Consultation with KiwiRail identified that the pipeline should be located more than 10 m away from the centre line of the rail line, preferably below the rail embankment, and that any vehicle access to the proposed alignment should have a fence or gate installed at the entry point to prevent public access and potential vandalism in the rail corridor. These design elements have been incorporated into the current design for the Project. Consultation with KiwiRail will continue during the detailed design and construction phases around the timing and methodology for connecting the new pipeline to the existing cross-connection beneath the rail corridor.

KiwiRail are required to provide a Deed of Grant to authorise works within their designations. The applicant has not yet applied for a Deed of Grant but it will do so before construction commences.

8.2.3.5 Waka Kotahi

Waka Kotahi have been consulted regarding the proposal with a meeting held on the 15th of July 2021 to introduce Waka Kotahi to the works required within the road corridor to connect the new pipeline through the existing cross-connection under SH 2 and the rail line. Waka Kotahi did not raise any particular concerns but did inform the applicant about the expected information requirements for any required application for works within the SH 2 corridor.


Further consultation with Waka Kotahi is on-going and approvals required from Waka Kotahi (CAR and s176 RMA approval) will be applied for post-lodgement and prior to construction in accordance with standard procedures.

8.2.3.6 Vodafone

Vodafone services will be potentially affected by the pipeline alignment as it approaches close to existing Vodafone infrastructure. Preliminary design plans of the pipeline alignment have been shared with Vodafone and any relocation of Vodafone assets will take place in compliance with their protocols.

8.3 Public engagement

Wider public engagement about the Project has not yet occurred. The primary method of public consultation will be through the formal notification of this application. To this end several information sources have been prepared by the applicant to inform the public about the potential effects and benefits of the Project:

– A project web site;

– Visualisations of the pipe bridge, to be supplied as a component of this resource consent and used in public consultation.

The notification of the Project should provide sufficient time and information for members of the public to engage with the Project should they wish to. Any issues raised by the public will be addressed following completion of the submission period.

8.4 Post-lodgement engagement

On-going communication will be undertaken post-lodgement of the resource consent applications. This will include on-going discussions with Mana Whenua (Ngāti Toa and Taranaki Whānui), key stakeholders, and affected landowners, sharing Project information with interested parties and providing updates via the Project website and local media. There will also be specific consultation activities and input into the detailed design and environmental monitoring activities from Mana Whenua, and the network utility operators whose services require protection or relocation because of works required during the construction of the Project.


9 Assessment of effects on the environment

9.1 Introduction and summary of effects on the environment

An assessment of any actual or potential effects that the activity may have on the environment, and the ways in which any adverse effects may be mitigated has been prepared in accordance with Schedule 4 of the RMA. The assessment is presented in such detail as corresponds with the scale and significance of the actual or potential effects that the activity may have on the environment. The assessment of effects on the environment from the Project is provided in the following sections of this report. The preliminary design for the Project, as reflected in this AEE and supporting drawings and assessment, has sought to avoid or mitigate adverse effects through the alternatives assessment, development of Project design features and the proposed construction methodology. The Project design has gone through a series of iterations against the parameters of the natural environment to achieve a design which achieves the Project objectives while avoiding, remedying or mitigating effects on the environment. Where it has not been practicable to avoid adverse effects, the applicant proposes measures, as set out in this section, to remedy or mitigate adverse effects.

9.2 Construction effects

9.2.1 Introduction

The Project construction methodology is described in section 5 and provides guiding principles and measures to avoid, remedy, or mitigate any adverse effects of activities on the environment. The final construction methodology will be developed by the Contractor once consent conditions are confirmed and detailed design has been completed.

9.2.2 Construction traffic

Disruption during construction will occur, as temporary traffic management and lane closures will be necessary to construct the bridge sections and sections of the pipeline (tie-in on western side of SH 2). In addition, during construction there will be an increase in traffic movements to and from the construction sites on Eastern Hutt Road and Fergusson Drive/SH 2 on both sides of Te Awa Kairangi/Hutt River.

The construction of the Project will take approximately two years. There will be delays to road users and localised access restrictions at times during construction of the Project. Given the scale of some of the bridge sections it may be necessary to close one lane of traffic at certain times to enable delivery of construction materials and during the launching of the bridge superstructure. Where possible delivery of larger construction materials and works requiring lane closure or disruption to traffic flows will be undertaken at off peak times. Providing access for construction vehicles, and minimising the impact for all road users and the community will be important.

Disruption to traffic will only be over a short distance where access for oversized construction materials and plant is required from Eastern Hutt Road and the Fergusson Drive intersection. This will be for short periods of time spread over approximately two years. The CEMP will include measures to manage and mitigate potential effects in accordance with the CoPTTM. It will identify how temporary access for all modes will be provided, and will require approval from UHCC and Waka Kotahi as RCA’s. Communications strategies will also be developed to ensure the traffic changes and anticipated traffic delays during construction are communicated with potentially affected businesses and the community. Under the CEMP businesses and residents will be informed of the programme of works and when there are likely to be traffic disruptions.


Works are intended to be undertaken during daytime, however there may be situations where work is required at night. The timing of works will be outlined in the CEMP.

9.2.3 Construction noise and vibration

Construction effects include increased noise and vibration. These effects will be typical of any construction activity and will be experienced mainly during standard working hours. If construction activities are required at night assessment of the expected construction noise will be undertaken, and if determined to be required, a consent for construction noise will be sought at that time.

In relation to construction vibration, there are no sensitive receivers within 380 m of proposed construction works and no relevant permitted activity standards for construction vibration in either the HCC DP or the UHCC DP. As a result, the effects of construction vibration have not been considered further.

In relation to construction noise, the proposed works will be undertaken using standard construction equipment and methodologies common to construction projects in New Zealand. The main sources of potential noise during the construction phase of the Project include:

– Heavy machinery including cranes and excavators;

– Heavy vehicles such as trucks;

– Stationary plant such as mobile generators and pumps;

– Piling, including percussion (impact driven) piling activity; and

– Use of construction tools such as welders and power tools.

The relevant noise assessment criteria are considered to be set out in the HCC DP, the UHCC DP and the New Zealand Standards in NZS 6803: 1999 Acoustics – Construction Noise.

To simulate the worst-case scenario, the sound power level from the loudest construction equipment to be used on the Project, being the impact pile driver which has a sound power level of 133 dBa52, has been identified to calculate the overall sound power level for the loudest expected construction activity at the nearest sensitive receiver. This approach is considered conservative as the Project extends over a large area and there will generally be a greater distance between construction equipment and sensitive receivers. In addition, given the highly trafficked Reynolds Bach Drive (Silverstream Landfill), industrial and commercial activities on Eastern Hutt Road and the proximity of SH 2 and the rail line, the ambient noise levels are expected to be relatively high.

Noise modelling undertaken for RiverLink which will also involve impact driven piling has been reviewed to understand potential noise effects for the Project. The RiverLink assessment demonstrated that an unmitigated noise level of approximately 65 dbA was expected at 300 m from the noise source. The findings of the noise modelling undertaken for RiverLink have been used to inform the assessment below.

9.2.3.1 UHCC District Plan

The UHCC DP includes a specific rule (Rule 32.3) addressing limits for noise from construction and demolition activities, which applies district wide. The limits and time frames set in Rule 32.3 of the UHCC DP generally coincide with the recommended upper limits in NZS 6803:1999 for construction noise received in residential zones and rural dwellings for construction activities of ‘typical duration’53 for the daily time periods of 0730 – 1800 and 2000 – 0630. The UHCC DP limits apply regardless of the total duration of the construction work (i.e.

52 Reference noise levels of construction equipment have been obtained from BS 5228-1:2009+A1:2014 Code of practice for noise and vibration control on construction and open sites – Part 1: Noise (“BS5228-1”), US FTA 2018 and AS 2436-2010 Guide to noise and vibration control on construction, demolition and maintenance sites (“AS 2436”). 53 Defined in NZS 6803:1999 as construction work at any one location for more than 14 days but less than 20 weeks


the rule does not set different standards for work of less than 14 days or more than 20 weeks). Rule 32.3 allows for a slightly longer daily period of high noise generating construction activities during normal workdays and Saturdays but also a longer period of ‘night time’ low noise limits, while NZS 6803:1999 recommends a more gradual daily increase and decrease in noise limits during normal work days, while being slightly more restrictive on Saturdays, and less restrictive on Sundays and public holidays.

To the extent practicable, construction activities will be undertaken during standard working hours (7 am to 6.30 pm). As a result, the Project will comply with UHCC DP standards for noise as the source of noise is the Open Space Zone and there are no Residential Zones or rural dwellings nearby. The nearest Residential Zone is located on Kiln Street in Silverstream54, approximately 900 m from the nearest piling activity. The nearest rural dwelling is located even further from the piling activity.

9.2.3.2 HCC District Plan

The HCC DP includes permitted activity conditions requiring:

- The maximum sound level shall not exceed Lmax 75dBA during the hours 10.00pm - 7.00am, measured anywhere within a residential activity area

- All construction, demolition, and maintenance work shall comply with NZS 6803P "Measurement and Assessment of Noise from Construction, Maintenance and Demolition Work".

Note: NZS6803P has since been superseded by NZS 6803:1999.

The HCC DP also prescribes specific noise limits for non-residential activities within Residential Activity Areas. The closest Residential Activity Area to the Project is Silverstream Retreat which is located within Noise Area 1. Noise Area 1 noise limits are:

Noise Area 1 Maximum 60dBA 7.00am - 10.00pm (Sun 9.00am - 4.00pm)

Maximum 45dBA 10.00pm - 7.00am

To the extent practicable, construction activities will be undertaken during standard working hours (7 am to 6.30 pm). The boundary of Silverstream Retreat is located over 380 m from the nearest point of piling activity and the closest building within the Silverstream Retreat boundary is over 450 m from the nearest point of piling works. As a result, construction noise at or within the boundary of Silverstream Retreat is expected to comply with NZS 6803:1999 'Measurement and Assessment of Noise from Construction, Maintenance and Demolition Work' and the noise limits for Noise Area 1 as set out in the HCC DP.

9.2.3.3 Measures to manage construction noise and vibration

Community engagement is often key to mitigating construction noise and vibration effects. Provided that the potentially affected receivers are informed, noise and vibration levels are generally tolerated because of the transitory nature of construction works.

Noise and vibration training should be part of the site-induction programme undertaken by all staff. Current noise and vibration issues/complaints should form part of the agenda at site meetings and toolbox talks.

The noisiest works should be kept within standard construction working hours where reasonably practicable. For example, driven piling works should be restricted to 7.30 am – 6 pm Monday to Friday, unless there is a practical reason why driven piling works are required outside of these timeframes.

54 There is a Residential Conservation Zone closer than this but there are no dwellings or other buildings within this zone that are closer than the 900 m to the Kiln Street Residential Zone


If determined to be required as a result of complaints, or noise monitoring during construction indicating an exceedance, further measures to minimise the impacts of construction noise can be adopted. Such measures could include noise curtains or timber cushioning in the base of the pile excavations to soften the noise.

Measures for communicating with affected receivers and the methods to monitor and manage construction noise, including but not limited to those identified above, will be outlined in the CEMP which will require certification by Council’s as secured by proposed conditions of consent.

9.2.3.4 Summary of effects of construction noise

Given the distance between construction activities and the nearest residential activity (Silverstream Retreat) the proposal is expected to comply with Rule 32.3 of the UHCC District Plan and Rule 14C 2.1.1 of the HCC District Plan. Overall, noise from construction activities is expected to be indiscernible from the high ambient noise levels in the Silverstream area. Accordingly, effects of construction noise are expected to be negligible.

9.2.4 Dust

It is unlikely that much (if any) dust will be generated by the activities, given the nature of the construction and the alluvial environment, as well as the high groundwater table in which works will be undertaken.

Dust from earthworks areas will be controlled through standard dust mitigation methods such as:

– Water cart(s) – used to dampen exposed surfaces

– Road sweeper/vacuum loading truck(s) – remove sediment/dust from site access areas

– Geotechnical fabrics – stabilise exposed surfaces

– Hay mulch – stabilise exposed surfaces

– Aggregate – stabilise exposed surfaces

Construction management practices will also be implemented to minimise the potential for dust effects to be generated. This includes measures such as controlling stockpiles, limiting the extent of exposed surfaces, avoiding overloading dumpers and vehicles transporting construction material and through careful monitoring of weather conditions. A proposed condition of consent is included requiring that dust generated during construction to not cause an offensive or objectionable effect at any point beyond the site boundary, and the inclusion of dust management measures and monitoring forms part of the requirements of the CEMP.

Because of the relatively modest scale of earthworks and exposed surfaces anticipated during the works, it is considered the potential generation of dust will be able to be appropriately controlled through standard dust mitigation measures to be implemented through the CEMP and will have negligible adverse effects.

9.2.5 Effects on public access during construction

During the construction phase, health and safety requirements will affect public access to Te Awa Kairangi/Hutt River in the vicinity of the construction area. However, this restriction will be localised and small relative to the extent of public access to Te Awa Kairangi/Hutt River outside of the construction area. Public access is currently restricted on the western bank of the Project site, with no access to this area available to the general public.

The areas requiring restrictions on public access during construction will be temporary and disturbance would be kept to the minimum to safely undertake the construction. The areas subject to restrictions at any particular time during the construction phase will be specified in the CEMP.

Pedestrian and cyclist access around the construction site will be maintained, with temporary access provided around the construction area for the duration of construction. Effects on the community as a result of


restrictions to access to the river corridor during the construction phase is described in further detail in the Social and Recreation Amenity Impacts in section 9.9 below.

The direct effect of restrictions on public access to Te Awa Kairangi/Hutt River as a result of these relatively small construction areas are assessed as negligible, given the extent of the wider river corridor available for recreation and access both upstream and downstream of the Project area.

9.3 Ecology

This section summarises the findings of the assessment of the actual and potential effects on terrestrial and aquatic ecology arising from the Project. The full assessment is contained in the Ecological Impact Assessment (Ecology Assessment) attached as Appendix F.

9.3.1 The receiving environment

The ecology of the receiving environment is detailed in section 3.6 of this AEE.

Table 21 summarises the ecological values (based on the EIANZ (2018) methods) for vegetation, and terrestrial and aquatic habitats found within the Project footprint. Overall, using the EIANZ (2018) guidelines, the terrestrial and wetland environment is of Low ecological value and the Te Awa Kairangi/Hutt River environment is of High ecological value. The unnamed tributary is of Negligible ecological value.

Table 21 Summary of Ecological Values assigned to affected habitats (as per EIANZ 2018)

Classification Habitat component

Repr

esen

tativ

e

Rarit

y

Dive

rsity

Cont

ext

Inte

grity

Conclusion

Terrestrial Planted vegetation (Manor Park restoration site and planted native patches)

VL L L L N/A Low

Riparian vegetation VL L L M N/A Low

Railway corridor vegetation L M L L N/A Low

Managed grasslands with exotic plantings VL VL VL VL N/A Negligible

Aquatic Wetland habitat VL VL VL VL N/A Negligible

Te Awa Kairangi/Hutt River M H M H H High

Unnamed tributary VL VL VL L VL Negligible

VL= Very Low, L = Low, M = Moderate, H = High, N/A = Not applicable

Table 22 below summarises the assessment of ecological values for fauna species which are likely to be found within the Project footprint during at least some stage of the year based on the EIANZ (2018) methods.

Table 22 Summary of Ecological Values assigned to affected fauna species (as per EIANZ 2018)

Fauna type Consideration Ecological Value

Herpetofauna and avifauna Northern grass skink, copper skink Low

Barking gecko, ngahere gecko (both unlikely to be present on-site) High

Black shag, little black shag, pied shag, bush falcon Moderate

Little shag and seventeen native, Not Threatened species Low


Freshwater fauna Longfin eel, koaro, dwarf galaxias, inanga, bluegill bully High

Four Not Threatened fish species, and two Not Threatened macroinvertebrate taxa

Low

Brown Trout Negligible

9.3.2 Assessment methodology

All ecological effects of the Project have been assessed using the Environment Institute of Australia and New Zealand Ecological Impact Assessment Guidelines 2018 (second edition) (the EcIA Guidelines), which is an industry best practice methodology for assessing the potential effects of a project.

The EcIA Guidelines have been used to ascertain the following:

1. The ecological value of the environment;

2. The magnitude of ecological effect from the proposed activity on the environment (without any effects management); and

3. The overall level of effect to determine whether an effects management response is required (i.e. mitigation).

Values of ecosystems and particular species55 are assessed against four criteria (and an additional criteria for aquatic habitats), and scored between ‘Negligible’ and ‘Very High’. Once the value of ecosystem components is determined, the measure of impact is assessed by the Magnitude of effect (extent, scale, duration and degree of change caused by an impact - Table 2356) with an overall level of effect between ‘Negligible’ and ‘Very High’ ultimately recorded as determined by the Matrix shown in Table 24.

Table 23 Magnitude of effect

Magnitude of effect

Description

Very High Total loss of, or very major alteration to, key elements/ features of the baseline conditions, such that the post development character, composition and/or attributes will be fundamentally changed and may be lost from the Site altogether; AND/OR loss of a very high proportion of the known population or range of the element/feature.

High Major loss or major alteration to key elements/ features of the baseline conditions such that post development character, composition and/or attributes will be fundamentally changed; AND/OR loss of a high proportion of the known population or range of the element/feature.

Moderate Loss or alteration to one or more key elements/features of the baseline conditions such that post development character, composition and/or attributes of the existing baseline will be partially changed; AND/OR loss of a moderate proportion of the known population or range of the element/feature

Low Minor shift away from baseline conditions. Change arising from the loss/alteration will be discernible but underlying character, composition and/or attributes of existing baseline condition will be similar to predevelopment circumstances/patterns; AND/OR having a minor effect on the known population or range of the element/feature.

Negligible Very slight change from baseline condition. Change barely distinguishable, approximating to the “no change” situation; AND/OR having negligible effect on the known population or range of the element/feature.

Table 24 Matrix for overall level of effect

ECOLOGICAL VALUE

Very High High Moderate Low Negligible

M A Very High Very High Very High High Moderate Low

55 With regards to species, the conservation status of all New Zealand biota have been assessed by DOC against a standard set of criteria and lists published. 56 Roper-Lindsay et al, 2018


High Very High Very High Moderate Low Very Low

Moderate High High Moderate Low Very Low

Low Moderate Low Low Very Low Very Low

Negligible Low Very Low Very Low Very Low Very Low

Positive Net Gain Net Gain Net Gain Net Gain Net Gain

Ecological significance was assessed in accordance with Section 6(c) of the RMA. Terrestrial habitats and fauna were assessed against Policy 23 and Policy 47 of the RPS. Natural wetlands were assessed against relevant definitions of the PNRP and NPS-FM. Freshwater habitats and fauna were also assessed against Policy 25 of the RPS, and Schedule F1 of the PNRP.

9.3.3 Effects on ecology

This section provides an assessment of the potential direct and indirect effects on ecological values associated with the construction and operation of the Project. The level of effects provided in this section does not incorporate any recommended remedy, mitigation57 or offsetting (i.e. is on the basis of no effects management). These potential ecological effects (and the activities that cause them) are discussed below.

The assessment of effects contained in this section is conservative. In many cases, it is likely the magnitude and overall level of effect will be less than what is described below (i.e. the below assessment reflects the worst-case scenario).

9.3.3.1 Terrestrial environment

Vegetation communities and habitats

The location and footprint of the vegetation communities within the Project area is identified in Figure 10 in section 3.6.1 of this report. The clearance of 0.6 ha (33% of the total area) of the Manor Park restoration site (administered by Forest and Bird) is considered to have a Very Low overall level of effect, as the vegetation community is not representative of any natural community type, and habitat removal will therefore result in a very minor shift from baseline condition.

Planted patches on the eastern floodplain, totaling 0.17 ha, have similarly Low ecological value and function, and their removal will have a Very Low overall level of effect.

The removal or disturbance of up to approximately 343 linear metres (up to 0.86 ha) of riparian vegetation within the Project footprint and an additional 24 linear meters (approximately 0.05 ha) along the western side of the river may be affected as part of the scour discharge infrastructure construction (within the scour construction footprint). This clearance amounts to approximately 7% of the length of riparian vegetation within this section of the river. The clearance required is expected to have a Very Low overall level of effect as the riparian species are common and the clearance and disturbance is small in the context of the riparian community both upstream and downstream of the Project.

Removal of 0.1 ha of broad leaf forest vegetation (predominantly māhoe) within the railway corridor is anticipated to have a Negligible magnitude of effect and Very Low overall level of effect as it would be a minimal shift from baseline.

Managed grasslands are a common feature along the Hutt River corridor within recreational spaces; clearance of 1.2 ha of grasslands on the eastern floodplain and 0.5 ha from the golf course and then a further either 0.19ha or

57Controls that can be reasonably assumed to be carried out as part of any construction works have been incorporated into the level of effect, e.g. contaminant storage and sediment control measures.


0.78ha within the golf course as part of the scour construction footprint will not be a significant deviation from baseline, or a Negligible magnitude of effect and will have a Very Low overall level of effect.

Herpetofauna

A population of northern grass skinks (and potentially a smaller population of copper skinks) persists within the Manor Park restoration site. This population is constrained to this site (by the road, river and golf course) and so it is unlikely to be able to disperse out of the area. Approximately 30% of the vegetation within this area (0.6 ha) is to be removed reducing available habitat. If unmitigated, this will likely result in the harming or mortality of any lizards residing within the clearance area resulting in a Moderate magnitude of effect, and an overall Low level of effect.

At-Risk arboreal lizard species have not been surveyed as they are not considered likely to be present within the Project area and if they are would be in very low densities. Regenerating māhoe, of which a very small proportion will be cleared (0.1 ha), is the only affected habitat where arboreal species have the potential to be encountered. Therefore, the magnitude of effect on arboreal lizards is expected to be, at most, Negligible, and the level of effect Very Low.

Given the limited mobility of lizards, the removal of vegetation will likely result in the mortality of lizards resident in the habitat unless salvage is undertaken. Notwithstanding a low magnitude of effect, native lizards are protected under the Wildlife Act 1953 and hence management to minimise mortality during habitat removal will be required to meet statutory obligations under the Wildlife Act, as well as good practice no net loss biodiversity outcomes.

9.3.3.2 Avifauna

Potential effects on avifauna are possible during both construction and operation of the Project.

Bridge design and operation

If cables on the network arch superstructure are positioned too close together (i.e. are not wide enough to allow birds to fly between the cables) or are not designed thick enough (i.e. are not visible to birds) the cables will provide a collision risk to birds if located within their flight corridors. Collision may result in injury or mortality of birds, and if at high numbers, may have population-level impacts on species.

The effect on particular species during operation is summarised below:

– Little shag and black shag - Due to the permanency of the bridge structure and the presence of other cable bridges within the vicinity of the Project, low risk of collision and low mortality risk is anticipated leading to a negligible magnitude of effect. A Negligible magnitude of effect on Low (little shag) and Moderate (black shag) ecological values results in a Very Low overall level of ecological effect.

– Bush falcon - Collision risk occurs when falcons are hunting prey; however, based on the static nature of the structure and the presence of other bridges within the vicinity of the Project, falcons are deemed to be tolerant of similar structures within their vast foraging ranges and therefore the magnitude of effect will be Low. A Low magnitude of effect on a Moderate value, results in a Low overall level of effect.

– Native, Not Threatened species - The flight behaviours, and because the river is not a key corridor for movement of these species, mean that collision risk is Very Low. If collision-induced mortality was to occur, it would have a Negligible magnitude of effect on population levels and an overall Very Low level of effect.

Bridge construction

Collision risk with the bridge during construction is also a hazard to avifauna species. The risk to shag species is negligible given that they pre-dominantly fly up and down the river corridor and not across it to areas outside of


the river margins where the bridge will be constructed. In addition, Not Threatened birds in the area do not exhibit flight behaviours that predispose them to collision risk. There is risk to bush falcon due to the gradual construction of the bridge however there will be time for the birds to become familiar with the location of the bridge. As a result the magnitude of effect is considered Negligible and there will be a Very Low overall level of ecological effect.

Habitat loss

Habitat loss will result from the removal of small areas of grassland, mixed native and exotic shrubland and willow trees during construction of the bridge. As the avifauna species that use the habitat in the Project area have low to Moderate ecological value and the magnitude of effect is Negligible as there is ample similar habitat nearby, the overall level of effect of habitat removal is Very Low.

Disturbance during construction

Disturbance and displacement of foraging, roosting and nesting avifauna species may occur during construction due to noise and construction activities. The impact on particular species is detailed below:

– Little shag and black shag - construction will remove some willow trees that provide suitable habitat for roosting, however the abundance of willow trees of similar sizes and ages along the riverbanks will provide alternative roosting habitat, resulting in a Negligible magnitude of effect and a Very Low overall level of ecological effect.

– Bush falcon - As falcons are highly mobile and have extensive home ranges, meaning they can relocate to other territories, the magnitude of effect is Negligible and the overall level of ecological effect is Very Low.

– Native, Not Threatened species - Negligible magnitude of effect is anticipated due to the temporary nature of the effect, the small size of the Project area and the abundance of similar habitat in close proximity. This results in a Very Low overall level of ecological effect.

9.3.3.3 Aquatic environment

Te Awa Kairangi/Hutt River

River and stream environment

To facilitate the bridge construction, in-river works will be required. The nature and longevity of the works in the river are largely dependent on the weight of the bridge and the assembly process. The potential effects arising from in-river works are considered separately below.

Causeway / work pad

To facilitate the bridge construction some works in the river corridor are required, including creation of a work pad for cranes to work from and construction of temporary bridge piers. The work pad/causeway will be disestablished following the completion of the superstructure of the bridge and the bed reinstated to approximately what existed prior to construction. The creation of a work pad will require gravel relocation and/or placement of pre-cast concrete panels to create a 15-20 m wide work pad / causeway. This may influence surface water flow paths; however, gravels within the river are already mobile and frequently redistributed during high flood/flow events. It is noted that re-construction of the temporary causeway or work pad may be required following heavy rainfall or flooding events.

Aquatic fauna is adapted to these conditions, and additionally, the gravel bed that is proposed to be utilised is frequently disturbed by recreational users. Recontouring of river gravels is not expected to have a measurable impact on the underlying character, composition, or attributes of the existing baseline. Given the prevalence of


gravel habitats throughout the Hutt River, this will have a minor effect on aquatic populations and macroinvertebrate community, resulting in a Low overall level of effect.

Temporary piers

Depending on the bridge installation approach adopted, coupled with the weight of the bridge, temporary piers may be installed within the river corridor to support bridge assembly. The temporary piers would be installed within the footprint of the causeway / work pad and would not be embedded into the bed of the river/bedrock. There is not expected to be any disturbance of the riverbed or interaction with surface flows in normal flow conditions, resulting from the temporary nature of the works, and effects will have already occurred with the formation of the work pad / causeway.

Permanent piers

The permanent piers will be, to the extent practicable, located outside the active river channel (outside flowing water). However, ground conditions, particularly the presence of splinter faults or geological deformations, may result in the pier closest to the true right (western) bank (Pier 2) being partially within the river channel. If this does occur, the pier is to extend from the river bank rather than be isolated within the channel (i.e. it will be contiguous with the riverbank). Given the small footprint of the pier this potential ‘worst-case scenario’ magnitude of riverbed disturbance equates to a Negligible magnitude of effect and overall a Very Low level of ecological effect on the aquatic environment.

Riverbank disturbance

The riverbank will be disturbed in areas where access to the river, vegetation clearance or ground improvement is needed to facilitate bridge construction. Te Awa Kairangi/Hutt River has High ecological value, but the river edges are highly modified with willow plantings and rock armouring.

The riverbanks will likely also be disturbed during the construction of Pier 2. Vegetation clearance may also result in bank disturbance as a result of erosion or scour over-time.

Project works will only result in a minor shift from existing baseline conditions when considering the wider riverscape, resulting in a Very Low overall level of effect.

Sediment discharge

There is residual risk of sediment discharge events when erosion and sediment controls are compromised by adverse weather events and extraneous material entering the watercourse. Fine sediment levels in Te Awa Kairangi/Hutt River are relatively low, with a corresponding high value macroinvertebrate community. Due to the size and flow of the river, its assimilative capacity is high and would require a substantive sediment pulse to notably alter the macroinvertebrate community structure; it is more likely that sediment discharge from works on the land will not be measurable beyond the zone of reasonable mixing and will only last a few days at most, resulting in a Low magnitude of effect and Low overall level of effect. It is also noted that potential effects of sediment discharge would be further reduced during periods of elevated flows when high turbidity levels are already present.

Contaminant discharge

Metals, hydrocarbons, oils and cleaning compounds contained in run-off adhere to sediment particles and can be absorbed by sediment feeding detritivores and/or plants. Given the small size of the proposed bridge and pipeline works relative to the high urbanisation levels within the Hutt River catchment and relatively small level of proposed impermeable surfaces that will be used (infrequently) by maintenance vehicles, any discharge of contaminants is unlikely to be measurable above the existing baseline. Contaminant release also predominantly


occurs during periods of elevated flow where contaminant loading in the river will be elevated due to the urban nature of the upstream catchment. Therefore, contaminant discharge is expected to result in a Negligible magnitude of effect and a Very Low overall level of effect.

Cement discharge

Cement and cement laden water (while unlikely) is the most likely contaminant to be released during construction (other than sediment). Cement will be used to pour the concrete required around the bridge piles, and to form the piers and areas of the abutments. Lime contained in cement is soluble in water and increases water pH to a level most fish species cannot tolerate (pH > 10) and can be fatal to aquatic fauna. Lime particles dissolve and spread through water meaning dilution of concrete discharges will actually exacerbate the problem and increase alkalinity (pH) of the water. As a result, adverse ecological effects from discharges of concrete or concrete laden water may extend beyond the point of discharge.

A concrete discharge event to Te Awa Kairangi/Hutt River will be expected to have a High magnitude of effect and a Very High overall level of effect.

Scour discharge

Periodically, scour water from the pipeline will be treated using sodium thiosulfate to remove chlorine before being discharged to Te Awa Kairangi/Hutt River via a pipe or grassed swale. Excess sodium thiosulfate concentrations can depress pH and dissolved oxygen concentrations, resulting in fish mortality. Assuming discharges to Te Awa Kairangi/Hutt River occur in flowing portions, the large assimilation capacity of the river means these adverse water quality conditions are unlikely given the rarity and limited duration of the expected treated scour water discharge events. This results in an, at most, Low magnitude of effect. This results in, at most, a Low overall level of effect.

Fish passage

Fish passage in Te Awa Kairangi/Hutt River will remain in place throughout construction and operation of the Project, as the works pad / causeway will not stretch across the length of the active channel (flowing water) meaning passage for fish will be maintained. Therefore, works in the river will have a Negligible magnitude of effect and a Very Low overall level of effect on fish passage.

Brown Trout

Brown trout have Negligible ecological value. Therefore, it would take a Very High magnitude of effect on brown trout before it becomes a Low overall level of effect rather than a Very Low overall level of effect on brown trout. Brown trout is the most recorded fish species in Te Awa Kairangi/Hutt River according to the NZFFD suggesting there is a healthy population within the river. Therefore, any potential disturbance to trout within the Project Footprint will have a Negligible magnitude of effect on the Te Awa Kairangi/Hutt River population, resulting in a Very Low overall level of effect on the Negligible ecological value brown trout.

Unnamed tributary

Sediment discharge

The bed of the unnamed tributary is dominated by a high sediment load and a macroinvertebrate community that is expected to be adapted to and tolerant of these conditions. The tributary is also not expected to have a stable fish population, if fish are present at all. Therefore, a sediment discharge is anticipated to have a Very Low overall level of effect as it is unlikely to alter pre-development discharge conditions.


Cement discharge

The potential effects of cement discharges are expected to be the same in the unnamed tributary as they are for Te Awa Kairangi/Hutt River as outlined above. Cement could enter the unnamed tributary during construction of the permanent ford/weir crossing. In summary, in the event of a discharge the magnitude of effect is expected to remain High, but as the tributary has Negligible ecological value a Very Low overall level of effect is expected.

Fish passage

Fish passage is currently restricted between Te Awa Kairangi/Hutt River and the unnamed tributary due to the perched culvert under the existing maintenance track which is likely to partially (if not completely) prevent passage. Fish passage is also anticipated to be poor (if present at all) underneath the rail corridor and SH 2 due to the lack of maintenance and condition of existing infrastructure which has resulted in significant sedimentation restricting flow and inability to locate the culverts.

It is anticipated that approximately 20 m of the unnamed tributary will be temporarily diverted and over-pumped to allow for the buried pipeline to be installed. The temporary diversion and disturbance of the tributary will alter the benthic condition within the affected reach but this will be a temporary effect and is unlikely to have a measurable impact on the wider aquatic ecology resulting in a Low magnitude of effect. Once the pipeline has been trenched under the tributary, a weir/ford structure will be constructed to provide permanent access to the pipeline (from the surface) for repairs and maintenance post-construction. The weir/ford will be designed to support fish passage in accordance with the NZ Fish Passage Guidelines and will not adversely affect fish passage.

In combining these two considerations, the more conservative Moderate magnitude of effect has been adopted. Therefore, a Moderate magnitude of effect on the Negligible value unnamed tributary results in a Very Low overall level of effect.

9.3.4 Measures to avoid, remedy or mitigate actual or potential effects

The Ecological Assessment recommends a number of actions to avoid, remedy or mitigate potential adverse effects on terrestrial and aquatic habitats, flora and fauna.

The overall approach to managing adverse effects of the Project on freshwater ecology follows the effects management hierarchy, in accordance with principles outlined in the PNRP and the NPSFM.

Measures to avoid, minimise and/or mitigate effects during the construction and operation of the Project recommended in the Ecology Assessment are summarised below. The applicant is proposing to implement these recommendations.

The full detail of how effects on ecological values will be addressed is to be further developed in an Ecological Management Plan (EMP), prepared by a suitably qualified ecologist, and specific conditions of consent to capture the recommendations included in the Ecology Assessment as outlined below.

9.3.4.1 Avoidance

Avoidance measures, where possible, have been incorporated into the iterative design process undertaken to date and further measures to avoid adverse effects, specifically related to avoiding both works and structures within flowing water to the extent practicable, will be considered during detailed design and construction activities.

The iterative design process has allowed for the following potential ecological effects to be avoided:

1. Effects on the potential wetland habitat have been avoided due to its inclusion in a “vegetation retention” zone;


2. The core lizard habitat within the Site (the area where the lizards were released in 2017, and where they continue to be monitored) was fenced early on to ensure avoidance during vegetation clearance and construction;

3. The proposed alignment for the pipe originally went through the regenerating vegetation to the north of the golf course; it has since been realigned to avoid the majority of this community;

4. Complete blockage of cross-sectional flows and fish passage within Te Awa Kairangi/Hutt River has been avoided via the use of a work pad / causeway (if needed) that does not extend the full width of the river;

5. The known shag roost trees on the eastern and western banks will not be felled or trimmed during construction works.

9.3.4.2 Minimise and remedy effects

The applicant proposes the following measures to minimise or remedy effects, as needed:

Terrestrial vegetation

– Vegetation loss will be minimised, including through site management and the physical delineation of vegetation to be retained or protected on-site;

– Planting of approximately 2.9 ha to remedy the loss of approximately 1.5 ha of low value native and exotic vegetation within the Project area; This is nearly twice the area of the vegetation being disturbed and should result in a net benefit.

– Weed control, including clearance of invasive exotic pest species, prior to construction works commencing to limit the spread of seed or stem fragments during vegetation clearance or construction;

– The contractor and project ecologist will conduct a site walkover and identify areas where the 12 m construction corridor proposed for pipeline trenching purposes should be reduced to minimise effects on indigenous vegetation;

The above measures will be secured through the development of Vegetation Removal and Planting Establishment sections in the EMP. These sections will outline the methodologies to minimise effects on existing vegetation and provide details of the replanting and maintenance and monitoring procedures, with the objective of improving the amenity and habitat values of revegetated areas in the Project area over the medium-long term.

Herpetofauna

– Vegetation clearance in lizard habitats will be avoided during colder months (May-August inclusive) when lizards are less active and less likely to be detected or survive relocation;

– Mitigating loss of habitat by improving the quality of the remaining habitat (through the addition of habitat components such as debris piles, rock piles, artificial cover objects), and by restoring the vegetation as soon as possible (where practicable) once works are complete.58

The above measures will be secured through development of a Lizard Management section within the EMP. The Lizard Management section will outline methods for salvage, relocation and habitat enhancement, incorporating all areas where lizards could potentially be present with the objective of improving the habitat values of Project features and revegetated areas for lizards.

58 As part of any lizard salvage process, a Wildlife Act Authorisation (permit) must be obtained from the Department of Conservation, to allow the handling, disturbance and relocation of lizards, as well as the incidental deaths of any that are unable to be salvaged.


Avifauna

– Lighting bridge cables from dusk-dawn during construction and operation with dim white light or pale coloured lighting to minimise potential bird collision risk; and

– Engaging a suitably qualified ecologist to undertake a pre-clearance check for roosting and nesting shags in the willows on the banks either side of Te Awa Kairangi/Hutt River prior to construction.

• If roosting shags are detected, felling will not occur until the birds have left the trees;

• If nesting shags are detected, an exclusion zone will be established around the tree(s) where construction works, which may impact nesting, cannot occur until nesting activities are completed.

The above measures to minimise effects on avifauna are to be secured through an Avifauna Management section in the EMP dedicated to management of effects on avifauna, and specific conditions requiring pre-clearance checks and monitoring of shag roosting and nesting behaviour (if identified) during construction activities.

Aquatic habitats

– Avoid, where practicable, peak spawning periods for potentially affected fish species, particularly bullies. If spawning periods (September – February inclusive) cannot be avoided a suitably qualified ecologist will advise on the feasibility of actively translocating egg masses and the attending male bully;

– Crane and machinery movements within the river channel will be minimised and the length of time the work pad / causeway is in place kept to the minimum duration practicable;

– To the extent practicable, efforts will be made to avoid working within the wetted channel or flowing water. In the event works in flowing water are required, fish rescue and relocation efforts are to be undertaken before the works commence;

– Temporary diversion of surface water to create dry working environments may be required, this includes in-river diversion of flow through recontouring of river gravels. If partial diversion(s) is required, then fish will be rescued and relocated from the affected area(s) prior to in-river works commencing;

– The contractor and a suitably qualified ecologist will undertake a walkover and identify areas where the construction corridor proposed for pipeline trenching purposes can be reduced to minimise effects on the unnamed tributary;

– Any permanent structure (weir/ford) to be constructed in the unnamed tributary will be constructed in accordance with the NIWA fish passage guidelines59 so that it does not inhibit fish passage in the event existing barriers to fish passage are remedied upstream and downstream of the tributary in future.

– Efforts will be made to discharge treated scour water to land rather than directly to the river. If piping is required, the pipe will terminate at the top of the riverbank to allow for discharge down the bank.

The above measures to minimise effects on aquatic fauna are proposed to be managed through an Aquatic Habitat Management section in the EMP, and specific conditions related to management of bullies, timing restrictions around in-river/stream works and ongoing fish passage requirements in accordance with the NESFW.

To mitigate the potential effects of sediment on water quality and aquatic ecology, an ESCP will be developed. The proposed ESCP (in addition to the CEMP) will also cover management of cement laden water and other construction related contaminants.

59 New Zealand Fish Passage Guidelines, NIWA, Franklin et al 2018.


9.3.5 Conclusion

With implementation of remedy and minimisation measures outlined above, which will be incorporated into appropriate sections in the EMP and otherwise secured by conditions of consent, the Ecology Assessment concludes that effects can be managed to a Very Low overall level of effect and there will be no residual adverse effects that would require offsetting (in accordance with Schedule G1 of the PNRP and NPSFM). The Project would therefore achieve an overall no net loss in indigenous biodiversity values and features with the potential for ecological benefits. Accordingly, ecological effects as a result of the Project are likely to be negligible.

9.4 Contaminated land


The environmental setting of the Project is predominantly low-lying and flat in the area adjacent to Te Awa Kairangi/Hutt River. Based on the local topography, the anticipated shallow groundwater flow direction is toward the Hutt River, at a depth of approximately 1.32 m below ground level extending to 4.35 m below ground level. The nearest surface water to the site is the Hutt River and the unnamed tributary.

A PSI undertaken identified that HAIL activities were ‘more likely than not’ to have presently or historically occurred within the Project area, in the form of rail yards and tracks (Category F6) and the Manor Park Golf Course (Category A10 – pesticide use).

9.4.2 Assessment of contaminated land effects

Construction works associated with the Project will require substantial soil disturbance. There is the potential that contaminated soils may be disturbed during the construction period of the Project, which would result in discharges of contaminants to air, land and water (surface and groundwater) where there may be an effect on the environment, and discharges of contaminants where there may be an effect on human health, including project construction workers, site workers and/or the public. The DSI (refer Appendix C) has assessed the suitability of each site for the intended land uses (recreation) and provided recommendation for management and/or remediation during the construction phase. A draft CLMP has been prepared for the Project (refer Appendix C)

The measured concentrations of the potential contaminants of concern in soil and groundwater are considered low. Although measured concentrations of some of the trace elements slightly exceed the published background rate, the spatial pattern of exceedances does not indicate a ‘hot spot’ of contamination and therefore these exceedances are considered to reflect published natural background concentrations. None of the concentrations of contaminants were above respective human health soil contaminant standards or soil guideline values for recreational land use. The measured concentrations in soil or groundwater are not considered to pose any unacceptable risks to human health or the environment. It is noted that consent has been sought under the NES CS for a controlled activity on a conservative basis, due to an area of the pipeline alignment through Manor Park Golf Course not having been sampled.

In addition, all of the results for groundwater are below the limits established in the Wellington Water global dewatering consent for the protection of freshwater and marine receiving environments, meaning groundwater encountered during construction works can be discharged to an appropriate surface water source.

9.4.3 Measures to avoid, remedy or mitigate actual or potential adverse effects

Potential adverse effects on human health and the environment, as a result of disturbance of contaminated soils, will be managed through the implementation of a CLMP and other specific management procedures that will be developed for construction (e.g. on site soil management practices, off site soil transport and disposal,


implementation of the ESCP, and the management of dust through the CEMP). With the implementation of the CLMP and the other specific management procedures, any effects on human health and the environment from contaminated land during construction will be adequately managed such that they are minor.

Management responses in the CLMP include:

– Ensuring reuse of contaminated soils is appropriate where deposited within the site for cut and cover areas.

– Where excess soil is required to be removed off-site, material must be deposited with the permission of the landowner and appropriate resource consents to receive the material must be in place. A review of the receiving land (its land use) should be undertaken.

– Verification of soil disposal landfill sites’ acceptance conditions with the contractor prior to transportation from the Project site to the landfill. Where measured soil concentrations are below or commensurate with published background concentrations that can be accepted as cleanfill, the facility must be contacted to ensure the soil can be received.

– Guidance for groundwater discharges, including a receiving source, and management and compliance requirements should be outlined in the ESCP and Dewatering and Settlement Monitoring Plan (DSMP).

9.4.4 Conclusion

A PSI undertaken for the Project has identified two land uses that historically occurred on the Project area that may have caused possible contamination, being the rail tracks and Manor Park Golf Course. The DSI has concluded that the measured concentrations of the potential contaminants are considered to be low and are unlikely to pose a risk to human health and the environment now or in the future.

9.5 Landscape, natural character and visual effects

This section presents the findings of the assessment undertaken to determine the actual and potential landscape and visual effects of the Project. This includes consideration of effects on the natural and urban landscape (including relevant aspects of urban design), natural character of the river environment and visual effects. This assessment is supported by the Assessment of Natural Character, Landscape and Visual Effects attached as Appendix G.


The receiving environment of the Project associated with an existing modified context following the margins of Te Awa Kairangi/Hutt River is summarised in section 3.4 and to a lesser extent section 3.7 of this report.


Assessment of the natural character, landscape and visual effects of the Project has been undertaken with reference to the Quality Planning Landscape Guidance Note (Boffa Miskell Limited)60 and examples of best practice, including: the UK guidelines for landscape and visual impact assessment61 and the New Zealand Landscape Institute Guidelines for Landscape Assessment62. Identified effects of the Project area have been rated using a seven-point scale ranging from ‘Very Low’ to ‘Very High’. The full assessment criteria is detailed in Appendix 1 of the Assessment of Natural Character, Landscape and Visual Effects (Appendix G).

60 https://www.qualityplanning.org.nz/index.php/node/805 61 Guidelines for Landscape and Visual Impact Assessment, 3rd Edition, 2013 62 Best Practice Note Landscape Assessment and Sustainable Management 10.1, NZILA


9.5.3 Assessment of effects

9.5.3.1 Natural Character

The surrounding modified extent of the Project area is assessed as contributing moderate to moderate-low levels of natural character. Te Awa Kairangi/Hutt River and its vegetated margins provide a wildlife corridor with moderate natural character; the river system and broad floodplain, including the presence of wildlife are important factors which contribute to natural character. The effects on natural character have been assessed having regard to the post-development state.

The proposed bridge structure spans a modified area of Te Awa Kairangi/Hutt River and will lead to a Negligible reduction in the levels of natural character in the context of this broader modified river corridor.

The design allows for Pier 2 of the bridge to shift up to 5 m into the design channel. During construction a temporary causeway or construction platform may be constructed of site-won river gravels. These activities will result in short-term disturbance of the river bed, although this occurs in a section of the river already heavily modified by existing bridge piers, flood protection works and the sewer weir, mitigating this impact.

At a finer scale:

– The proposed pipe bridge will appear suspended within a more modified part of the river corridor. This will result in a ‘lighter’ overall footprint within the river corridor and minimises long-term biophysical impacts within the primary active channel.

– The piers of the proposed bridge will occupy a modified open space setting, and the night lighting of the bridge aims to highlight it as an architectural feature without undue light spill, providing amenity and safety at a human scale and minimising potential for birds colliding with the bridge.

– There will be opportunities to restore riverside planting and to reinforce existing planted areas to preserve natural character associations within the modified river margin context.

– Vegetation required to be removed along the river margins to allow for the construction of the pipe bridge and scour discharge points will be replaced following construction with hardy native fast-growing grass and shrub species, along with longer lived tree specimens. If required, planting of sterile willow trees will be used for bank stabilisation.

Overall, levels of natural character effects are assessed as Low in this modified section of river corridor. Continued opportunities exist to enhance the existing condition though planting and associated habitat creation along river margins as part of the Project.

9.5.3.2 Landscape Effects

The following effects on existing landform from the Project have been identified:

– Temporary disruption of the landscape to bury the pipeline in the context of the existing road and rail structure. This will be apparent during construction, but landform effects generated by trenching can be rehabilitated at completion and quickly absorbed within the modified urban context.

– Construction of scour pipelines or swales beneath or across Manor Park Golf Course, to discharge scour water across rip rap armouring to Te Awa Kairangi/Hutt River

– Within the river channel, construction effects have been minimised using a network arch and truss structure. Pier 2 of the bridge may shift up to 5 m into the river design channel to respond to local ground conditions (e.g. avoid splinter faults) but will remain outside of the active channel. Construction occurs in an area that has already been subject to modification, adjacent to the river embankment, where areas of fill have occurred in the past. Beyond the design channel, landform disturbance will occur in association with the construction of piers, temporary bunding for flood control during construction, and construction of


earth embankments facilitating access onto the bridge. Such modification predominantly occupies existing modified embankments which reduces the landscape sensitivity of such areas.

– On the true right (western) bank, construction of the bridge will require substantial localised earthworks along the margins of the river. In the context of existing modification observed within the river corridor to facilitate piers and earth embankments enabling vehicle and pedestrian access; these effects will remain embedded in a highly modified local context that lacks any important landscape elements in an area largely obscured from public view.

– On the true left (eastern) bank, earthworks will be more prominent and will adjoin open space areas including the Hutt River Trail. Earth embankments respond to the margins of the river and facilitate planting designed to reduce visual effects. Landscape sensitivity in this area is reduced due to existing modified embankments.

Given the scale of disruption to the landscape required to construct a bridge in the river corridor, landform modification is expected to generate temporary Moderate-High adverse effects on the local landform. Overall, once areas of disturbance have been reinstated with grass and vegetation the Project will result in Moderate-Low adverse effects.

9.5.3.3 Vegetation clearance

Effects on existing vegetation include:

– Construction of the pipeline will entail some localised removal of shrub and tree planting adjoining the Silverstream Rail Bridge and along the margins of the railway corridor and golf course adjoining SH 2 and riparian vegetation removal at the scour discharge points.

– Construction of the pipe bridge will require the localised removal of planted exotic and native vegetation along the adjoining river banks and margins. On the eastern bank clearance is required to provide the platform for bridge assembly, construction compounds and for construction access to the river. On the western bank, clearance is associated with the 12 m construction corridor for the pipeline, the establishment of the access embankment and construction access to the river.

Removal of vegetation will result in Moderate-High adverse effects on existing landform, which are reduced to Moderate-Low with mitigation (replanting).

9.5.3.4 Landscape character

Landscape character effects include:

– The temporary disruption to existing open space characteristics and values during construction; and

– The permanent modification of the existing open space values and wider long-term impacts on the character and amenity of the Hutt Valley.

The pipe bridge will occupy an existing modified section of Te Awa Kairangi/Hutt River. Key changes to landscape character as a result of the proposed pipe bridge will result from the proposed removal of existing vegetation, earthworks and other associated construction activities, and addition of night lighting. Because of the modified landscape context in which these activities occur, landscape character effects are considered to be Moderate adverse during construction.

Once established, the proposed bridge structure will sit within the context of the existing Silverstream bridges and upstream of the wastewater weir and appear well integrated within this modified river corridor. Potential future pedestrian access will reinforce established recreation associations and proposed night lighting will highlight the bridge as an architectural feature within the river corridor ameliorating any temporary adverse landscape character effects. Once planting establishes, the proposed bridge is considered to become effectively


integrated within established bridge crossing in this modified context and generate Low neutral landscape character effects.

9.5.3.5 Summary of landscape effects

The proposed network arch option minimises disturbance to the riverbed by avoiding permanent structures in the design channel (to the extent practicable). The effects on landscape values are mitigated by the modified and vegetated river corridor in the context of existing bridges and a wastewater weir in which the proposed bridge will be located. Whilst effects on the existing landform and vegetation will be apparent, these effects will be temporary and exist in the context of existing road and rail infrastructure. Effects on landscape values are largely reversible once identified mitigation (planting) has become established.

A summary of the identified landscape effects is set out below in Table 25.

Table 25 Identified landscape effects

Without Mitigation With Mitigation

Description of Effect Level of Effect63

Nature of Effect64

Level of Effect

Nature of Effect

Effects on existing landform

Temporary disruption to bury the pipeline in context of existing road and rail infrastructure. Construction of the bridge will require substantial localised earthworks along the margins of the Hutt River in the context of existing modification observed of the river corridor to facilitate piers and earth embankments enabling vehicle and pedestrian access Earth embankments respond to the margins of the river and facilitate planting designed to reduce visual effects

Moderate - High

Adverse Moderate - Low

Adverse

Effects on existing vegetation

Construction of the pipeline will entail some localised removal of shrub and tree planting adjoining the Silverstream Rail Bridge and along the margins of the railway corridor and golf course adjoining SH2 Construction of the proposed pipe bridge and scour discharge points will require the localised removal of planted exotic and native vegetation along the adjoining river banks and margins

Moderate-High

Adverse Moderate Low

Adverse

Landscape Character Effects

Proposed pipe bridge occupies an existing modified section of the Hutt River Potential future pedestrian access will reinforce established recreation associations Proposed night lighting will highlight the bridge as an architectural feature within the river corridor

Moderate Adverse Low Neutral

9.5.3.6 Visual Effects

To understand the effects of the proposed development, the assessment has included the preparation of three indicative visual simulations from representative viewpoints, showing the proposed bridge in its landscape context with mitigation (year 5). Visual effects have been considered from public and private vantage points.

63 Level of Effect assessed as: Very High, High, Moderate-High, Moderate, Moderate-Low, Low, Very Low 64 Nature of Effect assessed as: Adverse, Neutral or Beneficial


Views from public areas

Open views of the bridge will be limited to when the public are approaching and passing immediately beneath the bridge structure due to existing vegetation and the railway and road bridges’ obscuring views.

To the south of Hull’s Creek, along the river corridor and Hutt River Trail, public views will remain relatively well-contained as the structure will be screened by established vegetation. During construction the disruption to the context of open recreation space and established areas of vegetation is considered to generate moderate-high adverse effects. Following completion, the bridge will represent a distinct natural built environment that blends within the vegetated backdrop and existing river crossings, which will generate Moderate-Low effects.

Effects from Eastern Hutt Road and Reynolds Bach Drive are considered to be Low adverse, as the bridge will represent a distinctive and contained localised element in the context of existing modification. Planting along the new embankment reinforces the green corridor along the river edge. Where visible, which will be limited to glimpsed views of the proposed pipe bridge, including night lighting, the pipe bridge will be a localised feature seen within established modified influences.

Visual effects from Manor Park Golf Course are anticipated to be Moderate to High adverse during construction due to removal of vegetation and construction of the underground pipeline next to fairways and the construction of the scour pipes or swales will be visible from parts of the golf course. Once the golf course has been re-instated (e.g. re-grassed) following burial of the pipe, residual effects will be Low.

Rail corridor

Users of the Hutt Valley Rail Line will experience transient views of the construction and finished pipe structure due to existing vegetation along the rail corridor, resulting in Low adverse effects. Removal of vegetation will increase glimpses of elevated parts of the bridge structure for train users. Any views from the railway bridge will be fleeting and observe a new landmark bridge suspended structure above the active river bed and embedded within vegetation established along river banks. In this context the proposed bridge is expected to generate Low adverse effects.

State Highway 2

The removal of vegetation between the golf course and the rail corridor will open up glimpsed views of elevated parts of the arched bridge structure for users of SH 2. Any views from the railway bridge will be fleeting and observe a new landmark bridge suspended structure above the active river bed and embedded within vegetation established along river banks. In this context the proposed bridge is expected to generate Low neutral effects.

Private residences

Effects from private vantage points may be experienced from the southwest at Silverstream Retreat, Silverstream Rail Museum and the Northpower Building at 410 Eastern Hutt Road. Glimpsed views may also be experienced from the dwellings at 2 and 15 Reynolds Bach Drive. Views from these properties and private residences are largely obscured by the landform and existing vegetation. Due to the screening by vegetation for all private buildings and the bridge being a localised feature seen within established modified influences, the Project will have no more than Low effects.

9.5.3.7 Summary of visual effects

Despite the scale of the proposed bridge structure, views remain confined to a limited area of the Hutt Valley and associated Hutt River corridor. Views will be most apparent from the true left bank of the river along the Hutt River Trail, where pedestrians and cyclists will experience open views passing beneath the southern end of the bridge structure. Whilst some temporary more substantial adverse effects will be apparent during construction,


given transient views will be experienced in the context of existing modification including existing adjoining bridges and the weir structure.

From further afield the proposed bridge becomes more difficult to see, generating only Low and Very Low effects.

Cumulative Effects

The construction of a new pipe bridge across Te Awa Kairangi/Hutt River will be observed in the context of existing bridges and a weir structure and remain largely contained within established areas of vegetation which occupy and enclose this modified section of river corridor. Similarly, landscape effects will remain contained and primarily associated with temporary vegetation disturbance which can be effectively rehabilitated through replacement planting. The potential for improved recreation access combined with the pipe bridge would provide an additional benefit in terms of recreation use currently accommodated in this area. Given this contained modified context associated with existing structures crossing the river, any cumulative effects will be limited and remain no more than minor once established.

The potential for improved recreation access combined with the pipe bridge, provide an additional benefit in terms of recreation use of the river corridor.

9.5.4 Measures to avoid, remedy or mitigate actual or potential effects

A range of measures have been proposed to avoid, remedy or mitigate landscape and visual effects which have been identified for this Project:

– Areas of exposed soil should be reinstated to resemble the existing landform and reinstated with grass or vegetation as set out in the Landscape Concept Plans, within the next available planting season.

– The proposed colouring of the pipe bridge should be selected from materials in the natural range of greens, browns or greys with a low reflectivity to appear recessive against a vegetated backdrop.

– Planting designed to mitigate implementation of the bridge structure should promote habitat creation and safe pedestrian access where relevant. Such planting should be in general accordance with landscaping as set out in Figures 6: Pre-Construction and Remediation and Figure 6a Revegetation Strategy (Appendix G) address the following:

• The extent of existing vegetation to be retained within the site;

• Areas of vegetation proposed to be removed;

• Species, spacings and sizing of identified planting areas.

– Lighting to be designed to contribute to the safety and architectural feature of the bridge structure in general accordance with Figure 7: Bridge Lighting Concept (Appendix G).

– A Final Urban Design and Landscape Plan (UDLP) should be prepared for the proposed development. The UDLP shall include detailed design drawings and outline landscape treatment for all permanent structures, landscape and public space features, safety and amenity features and signage.

– The UDLP shall be consistent with the Planting Establishment and Management section of the EMP which outlines:

• The native species that are proposed to be planted, the size of the plants and the density of planting;

• Details of the on-going maintenance of the planting including, but not limited to, the replacement of plants, future management, and eradication of pest plants

• Details of the proposed monitoring regime.


9.5.5 Conclusion

The bridge structure and buried pipelines will be integrated and located within an area of existing modified character, resulting in avoidance of significant adverse landscape and natural character effects.

Temporary adverse visual and landscape effects will occur during construction through disturbance from earthworks and vegetation removal. Once completed, the proposed works will accommodate replacement planting to mitigate the effects of disturbance within a modified river margin context and support potential for enhanced recreational opportunities, including potential links to existing and future recreational trails established in this area.

Overall, the bridge will appear carefully sited with no more than minor impacts on the existing natural character and landscape amenity values along the river corridor.

9.6 Dewatering

This section summarises the findings of the assessment of the actual and potential effects of the Project on groundwater arising from dewatering during the construction activities. A full assessment is provided in the Assessment of Dewatering Effects attached as Appendix D.


The context of the groundwater system as it relates to the potential effects of dewatering is outlined in sections 3.4.2 Geology and 3.5.3 Groundwater of this report.


Two-dimensional groundwater modelling was undertaken to assess the likely magnitude and extent of groundwater flows and drawdowns that could result from construction-related dewatering. The modelled inflow rates and volumes were used to assess whether dewatering would likely be a permitted activity or whether WWL’s global dewatering consent would need to be relied upon for dewatering activities. The modelling also aided in assessing site-specific settlement potential and whether any management response was required.

Two cross sections were created using Geostudio 2019 SEEP/W finite element numerical modelling software to represent the two largest and deepest excavations, one at the Eastern Hutt Road connection chamber and the other at the location of a scour manhole on the western bank, that were anticipated to encounter groundwater. The utilised software is able to model the unsaturated flow conditions that can occur when an excavation is dewatered. Modelling indicated that a zone of influence from the effects of drawdown could be expected up to approximately 210 m from dewatering activities.

9.6.3 Assessment of dewatering effects

Based on groundwater level measurements, it is anticipated that the majority of excavations for works will not reach the groundwater table. However, a few of the larger/deeper excavations for scour valves and connection chambers will intercept groundwater levels. Therefore, dewatering will be required.

Existing water users

A conservative radius of 500 m was applied and the GWRC database was checked to identify any groundwater users within this radius. 23 bores or wells were identified within this 500 m radius, the bores are generally shallow, with depths of 3.4 -18 m below ground level. Fifteen of the bores are located within 210 m of the proposed alignment but are not within 210 m of the proposed connection chamber where the greatest level of


drawdown is anticipated (>0.2 m). One bore is located within the 0.2 m drawdown radius of the scour manhole excavation on the western bank but is considered unlikely to exist.

As there are no consented surface water users or noted groundwater use bores within the expected drawdown radius of 210 m, the effects from the short-term dewatering on surrounding water users is expected to be negligible.

It is understood there is an existing irrigation bore within Manor Park Golf Course, approximately 600 m southwest of the alignment. However, modelling has indicated that the drawdown radius will not extend that far; therefore, there is expected to be no effect from dewatering on the Manor Park Golf Course irrigation bore.

Surface water bodies

Seep sections and analysis have identified that shallow groundwater is hydraulically connected to Te Awa Kairangi/Hutt River and therefore any dewatering could cause a degree of river depletion. However, dewatering of each excavation will be of a short duration and water will be extracted at relatively low pumping rates. As noted in section 9.4 of this report, the DSI has determined that contaminants in groundwater are below the concentrations beyond which water is not safe for human health and aquatic species in the Wellington Water global dewatering consent. All dewatered water is to be treated and returned to Te Awa Kairangi/Hutt River and therefore no water will be lost from the system.

Therefore, the Assessment of Dewatering Effects concludes effects on surrounding surface water bodies are likely to be negligible.

Potential for settlement on existing infrastructure

Dewatering of excavations has the potential to cause surface settlement which may affect nearby assets. The replacement pipeline will be constructed parallel to existing utility lines along Eastern Hutt Road, and the nearest building is 60 m from the embankment and connection chamber works. Settlement potential was analysed based on geotechnical conditions and calculations concluded that settlement adjacent to the proposed excavations is expected to be negligible considering the dense, granular in situ material that is found across most of the site.

9.6.4 Measures to avoid, remedy or mitigate adverse effects of dewatering

Measures to avoid, remedy or mitigate adverse dewatering effects are centred around monitoring. Monitoring is proposed to record groundwater levels and groundwater quality prior to, throughout and following construction activities. This will allow actual changes to groundwater to be checked against those modelled and appropriate responses to be implemented, if needed.

While there is negligible settlement anticipated, a Dewatering and Settlement Monitoring Plan (DSMP) (refer Appendix B of the Assessment of Dewatering Effects (Appendix D) has been prepared which outlines the recommended monitoring programme, trigger levels and contingency actions should drawdown be shown to be greater than anticipated. An appropriate construction management and monitoring methodology, prepared by the construction contractor in general accordance with the draft DSMP, will enable tolerable limits of drawdown and settlement to be maintained such that no adverse effects are realised within existing buildings, utilities or other infrastructure.

In summary, the draft DSMP recommends that existing monitoring wells on site are monitored pre, during and post construction, and that a series of settlement pins and settlement markers be installed along adjacent embankments, road bridges and buildings. Indicative locations for settlement pins and markers are provided in the draft DSMP. Settlement pins are also recommended in Manor Park Golf Course, between the pipeline and rail line, due to uncertainty of the condition of the fill below the rail corridor. The draft DSMP recommends


monitoring points be surveyed prior to dewatering commencement, during construction and post construction in accordance with the frequency outlined in Table 26 below.

Table 26 Instrumentation monitoring frequency

Instrumentation Monitoring Frequency

Pre-Construction During Construction Post Construction

Settlement Pins/Markers

Once Daily until the reading is stabilised, then twice a week for two weeks followed by weekly.

Once a week for four weeks followed by fortnightly for three months in total or liability periods whichever is greater

Trigger levels presented in Table 27 below and detailed in the DSMP should also be adopted to provide early warning of settlement and enable appropriate response measures to be implemented.

Table 27 Trigger levels for settlement monitoring during construction

Level Settlement Value Action

Level 0 <5 mm Best estimate of ground behaviour. No action required.

Level 1 (Alert Value)

5 mm Increase monitoring frequency and implement contingency actions

Level 2 (Alarm Value)

15 mm Cease dewatering and implement contingency / mitigation measure to limit/address differential settlement exceedance.

If settlement during dewatering activities exceeds 15 mm, the work shall be stopped immediately, and an appropriate mitigation strategy, developed alongside GWRC, shall be implemented.

A condition of consent requiring the submission of a final DSMP prepared in general accordance with the draft DSMP has been proposed to ensure dewatering and settlement effects are appropriately managed. The DSMP shall include as a minimum:

– Duration, location, volume and rate of any dewatering required

– Quality of water to be discharged

– Effects of land subsidence

– Effects on surface water bodies and interference effects on any known lawfully existing water takes at the time of construction

– Measures to avoid and/or mitigate any potential adverse effects from dewatering activities on nearby buildings and infrastructure; and

– Groundwater level monitoring requirements and trigger levels, including:

• Location of monitoring pins/markers

• Contingency actions in the event trigger levels are exceed;

• Reporting requirements

9.6.5 Conclusion

Numerical modelling has been undertaken for the two larger excavations (chamber connection and scour valve and manhole).

No current groundwater or surface water users have been identified within the radius of influence of the drawdown. No adverse effects on surrounding water users are anticipated. Pumping is to be of a short duration, with all water returned to adjacent surface water bodies once it meets appropriate water quality standards.


Effects of dewatering on nearby surface water bodies is considered to be negligible. Settlement adjacent to the excavation is expected to be negligible.

Monitoring via settlement pins/markers and groundwater levels is recommended to protect surrounding infrastructure, and monitoring of existing monitoring wells. The DSMP outlining the recommended monitoring methodology and trigger levels has been included in the Assessment of Dewatering Effects. Appropriate construction management and recommended monitoring will ensure that tolerable limits of drawdown and settlement are maintained such that no adverse effects are expected to be experienced by existing water users or within existing buildings, utilities and other infrastructure.

9.7 Natural hazards and geotechnical risk

Natural hazards have shaped the Hutt Valley and Te Awa Kairangi/Hutt River into their current forms, and will continue to impact the Project area and wider region. The Project will continue to be at risk from these natural hazards.

9.7.1 Seismic

Numerous active faults are located in the Wellington region, including the Wellington Fault itself which traverses the western bank of Te Awa Kairangi/Hutt River within the Project area, and gives rise to various earthquake-related risks.

The likelihood of rupture of the Wellington Fault, ground shaking from an earthquake and the associated liquefaction, lateral spreading, regional uplift/subsidence and earthquake induced slope instability could cause severe effects on Project elements. The earthquake hazards identified cannot be avoided unless the Project is not constructed, and cannot be remedied. However, the effects can be mitigated through design and construction. Natural hazard risks to the Project will be addressed adequately and appropriately through standard detailed design process and the Building Act 2004 approvals required for the structures

The Project does not cause or exacerbate land based natural hazards in other areas.

Analysis of liquefaction identified a potentially liquefiable layer at the proposed access embankment on the eastern end of the pipe bridge. However, excavation of the embankment footprint is expected to exceed the depths of the potentially liquefiable zone. This will remove the liquefaction prone soils from under the embankment and therefore remove this risk. The analysis indicated that the liquefaction potential for the remaining portions of the pipeline and pipe bridge is minor to none.

Such design and construction can mitigate the effects of many of the natural hazards. The pipe bridge will be designed and constructed with a seismic design philosophy that is in accordance with the Bridge Manual, the best practice standard for bridge construction.

9.7.2 Flooding

As outlined in section 2.5.4 the pipe bridge will be designed for a 2800 m3/s flood event in Te Awa Kairangi/Hutt River and the in-ground portion of the pipeline will be designed with a risk-based approach that considers the relative impacts of significant seismic and flood events, including potential scour impacts.

The effects of the Project on flood risk and scour are outlined in detail in the Hydraulic Assessment contained in Appendix E. These effects are summarised below.

9.7.2.1 Flood risk

Hydraulic modelling was completed to determine the impact of the proposed bridge on flood levels and inform the design of the pipeline and the bridge to mitigate flood and scour risks.


Hydraulic modelling was completed using the MIKE FLOOD calibrated hydraulic model of the Hutt River and floodplain provided by GWRC Flood Protection. Additional hydraulic modelling was completed using a one-dimensional river model built with HEC-RAS software. This was built as an extract of the existing MIKE FLOOD model. The model covers the proposed pipe bridge location and extends approximately 1300 m upstream and 1000 m downstream of its location.

Full details of the model parameters and results can be found in the Hydraulic Assessment (Appendix E).

Hydraulic flood modelling with the proposed bridge structure in place has shown minor increases in flood levels in the river channel in the 2800 m3/s flood event. Within the river channel, flood levels are expected to increase 20-30 mm upstream of the proposed pipe bridge. There is no flood level impact upstream of the existing road bridge at Silverstream or downstream of the proposed pipe bridge. In the event Pier 2 has to be shifted 5 m from its current location into the design channel, which reflects the worst case scenario, there would be a further increase in flood level of approximately 5 mm.

Based on a maximum increase in flood levels in a 2800 m3/s flood event of 30 mm at the proposed bridge, it is reasonable to conclude that only similar increases in flooding outside the river corridor are possible and the effects of these will be negligible. The bridge location is in a section of the river where there are no stop banks, and the effects of larger floods (than the 2800 m3/s flood) are assessed as having only limited further increases in flood depth.

9.7.2.2 Effects of scour

Movement of the river channel within the Erosion Zone has been taken into account through the design of the bridge piers and the embankment. As identified in section 2.5 of this report, it is not feasible to build a bridge that spans this full width given the position of Eastern Hutt Road and the railway. All of the bridge piers and the eastern embankment are located within the 80 metre Erosion Zone and therefore scour analysis has been completed for the current river bed profile and an assumed future river profile where the toe of the bank has migrated 80 metres either side of the river65.

The calculations show a potential scour depth of 2.5-3.7 m at the bridge piles. The bridge has been designed to withstand scour at the piles up to the depths predicted by the hydraulic modelling and to be structurally resilient in a 2800 m3/s flood event. In the case of a 2800 m3/s flood event or where over time the channel bank migrates 80 m east (up to the edge of the Erosion Zone), the eastern embankment will be undermined.

For the seismic design case, no significant scour is assumed. The likelihood of a 1 in 2800 m3/s design flood followed by a 1 in 2500 year design earthquake is extremely low. To design for a design flood event which scours the soil at the piles, followed by a design seismic event would be cost prohibitive.

9.7.2.3 Management of effects of scour

The eastern embankment will be constructed with Duramesh facing under the bridge on the river side and reinforced soil throughout. The Duramesh facing is designed to withstand moderate flood velocities and modelling at the 2800 m3/s flood event indicates maximum velocities of 1.1 m/s adjacent to this face which is within the design range of the Duramesh product.

The embankment does not provide structural support for the bridge, the structural integrity of the bridge will not be impacted however maintenance vehicle access from the eastern side in a significant flood event will be impeded. Although this embankment is required for rapid maintenance after a seismic event, in a flood event the

65 Potential scour at the piers and abutments was calculated using the HEC-RAS model and Hydraulic Engineering Circular No.18 (HEC No. 18) produced by the US Department of Transportation - Federal Highway Administration (FHWA).


bridge height (above the flood level) mitigates damage to the pipe. The western side of the bridge is also assessed to remain accessible during and after a 2800 m3/s flood event.

In addition, there is the potential for a section of the in-ground pipe adjacent to the eastern embankment to be exposed following embankment scour or if there is a breach of the embankment from floodwaters on the Eastern Hutt Road side.

A number of options were reviewed to design the embankment for the same flood criteria as the bridge structure. However, these were deemed to be not required at this time. As part of the proposed Landscape Concept Plan (found in Appendix G), deep rooted plants will be planted along the river banks and within the reserve area and will prevent some potential erosion. If during the life cycle of the pipe bridge there are signs of significant erosion affecting the eastern embankment (and the road), localised scour protection (rock rip-rap) or bank stabilisation works could be implemented to minimise the need for costly repairs.

9.8 Cultural values

Te Awa Kairangi/Hutt River has a strong association with Te Āti Awa hapu of Ngāti Te Whiti, Ngāti Tāwhirikura, and others of Te Āti Awa nui tonu including Ngāti Tama, and historically with Ngāti Rangatahi, Ngāti Toa Rangatira and Ngāti Hāua.

The applicant has consulted with Mana Whenua during the development of the proposed design solution. In particular, Mana Whenua from Taranaki Whānui have been involved in the MCA process. A Position Statement has been prepared on behalf of Taranaki Whānui (refer Appendix L). This assessment describes the relationships of Taranaki Whānui to the whenua and awa and provides recommendations for mitigating effects on cultural values. The Position Statement requires that consultation with Taranaki Whānui shall continue during the design process, development of management plans and through collaboration on conditions of consent providing opportunity to deepen human, spiritual and cultural connection with the river environment.

Since the initial response from Ngāti Toa received in October 2020, the applicant has made further attempts to obtain the feedback of Ngāti Toa with no additional response from Ngāti Toa received to date. Ngāti Toa will be able to make a submission reflecting any concerns or opinions they have regarding the Project during the notification period of this consent application.

9.8.1 Values

Te Awa Kairangi is subject to a statutory acknowledgement for both Taranaki Whānui and Ngāti Toa. As identified in section 3.3 of this report, Te Awa Kairangi is listed as Ngā Taonga Nui a Kiwa for both Taranaki Whānui and Ngāti Toa within the PNRP.

Te Awa Kairangi/Hutt River historically was highly important for the abundance of freshwater fish and the Pā and kāinga which extended along the river valley or along its main tributaries.

The identification of other traditional cultural values is derived from traditional uses of the Project area in both the river and the banks and cultural sites in or near the Project area. However, the key sites to Mana Whenua are located downstream of the Project area, closer to Boulcott and further downstream towards the river mouth.

The Project area is not known to contain any sites of cultural significance to Mana Whenua. As noted in section 8.2.2.1 the applicant has consulted (or made efforts to consult) with relevant iwi to understand their views of the Project and allow the project team to understand any potential impacts on cultural values to inform the detailed design and construction methodologies for the Project.


9.8.2 Effects on cultural values

In general, excavation and construction works have the potential to destroy Māori archaeological sites on the banks of rivers, however it is unlikely that archaeological sites will be destroyed because of the level of activity in colonial times in this area of the river and the geomorphology of the ‘active’ river terraces in this area. However, archaeological remains could be accidentally discovered during works.

For iwi / Mana Whenua, the works in the bed and on the banks of the river are of high significance especially because spiritual and cultural well-being is strongly linked to the ecological health of the Te Awa Kairangi/Hutt River and its ecosystems.

9.8.3 Measures to avoid, remedy or mitigate effects on cultural values

Various methods have been identified to mitigate potential adverse effects on cultural values as a result of Project works. An Accidental Discovery Protocol has been proposed as a condition of consent, and will be in place for the duration of construction as a mechanism to protect any Māori cultural material found during construction. In the event that koiwi (human skeletal remains) or other artefacts are discovered the work in that area will stop to allow site inspection by tangata whenua representatives and/or Heritage New Zealand (as appropriate), who will determine the extent of the discovery, and whether a more extensive site investigation is required. Any cultural artefacts or materials discovered will be handled and removed by tribal elders responsible for the tikanga appropriate to their removal or preservation.

The measures listed below are also anticipated to appropriately avoid, remedy or mitigate any remaining effects on cultural values:

– Salvage and relocation of indigenous fauna prior to works and restrictions of works in the river channel during peak spawning and migration periods of indigenous fish;

– Erosion and sediment controls;

– Planting of the river banks and floodplain with native species to enhance habitat and food sources for indigenous fauna, and

– Opportunities for recognition of the connection of Māori to Te Awa Kairangi/Hutt River to be provided by the Project through interpretive features and naming of parts of the Project.

The community will see some benefit arising from the pipe bridge, particularly with improvements to pedestrian and cycle access and restoration planting that will improve habitat for wildlife. In this regard, more attractive places for recreation and the improved ability to use cycle and walking paths generally have a positive health benefit to all, including Māori.

9.8.4 Conclusion

A range of measures to mitigate potential adverse effects on cultural values are proposed, in particular the use of an Accidental Discovery Protocol. Overall, the effects of the Project on cultural values are expected to be minor. The Project further offers opportunities through interpretive features to enhance cultural and heritage values and share them with the wider community.

9.9 Social and recreation impact

This section outlines the social effects assessment in relation to the Project. These effects focus on the experiences (actual or anticipated, direct or indirect) of individuals, businesses, and communities’ response to changes in the Te Awa Kairangi/Hutt River corridor and to local roads and transport patterns.


9.9.1 Effects on social and recreation values

The construction and operation phases of the Project have the potential to generate both positive and adverse regional and local social effects.

The Project is anticipated to have significant positive impacts to the local and regional community, and as such the Project has a high level of support from those members of the community that the Project has consulted with (refer section 8). These benefits include improving the resilience of the bulk water supply network against future flood and seismic events, improved access to Te Awa Kairangi/Hutt River in this location and the opportunity to improve connections to planned and existing pedestrian and cycling networks. A notable benefit of the Project is that it will provide opportunities for the community to access an area of the river corridor on the western bank not previously accessible by the general public, creating new space for recreation alongside the margins of the river.

The Project will also have some significant impacts, and these are predominantly related to the construction phase. Construction impacts are anticipated to extend for around two years. There are both positive and adverse social effects identified during construction of the Project. The positive construction related effects include the opportunity for creation of local construction jobs. Negative impacts include uncertainty surrounding traffic and river access issues, visual, noise and health impacts of construction, loss of access to the active transport along the Hutt River Trail and restrictions to access to recreation activities within the river corridor at Silverstream during construction.

9.9.2 Measures to avoid, remedy and mitigate adverse effects on social and recreation values

Key mitigation measures proposed to address adverse social and recreational effects of the Project are:

– Preparation of a CEMP which includes requirements around communications regarding changes to traffic arrangements. Communication should include information about alternative access and travel options, complaint management process and updates on construction phasing.

– Staging of the Project to consider minimisation of longer term impacts to specific stakeholders such as the businesses on Eastern Hutt Road.

– A walking and cycling trail will be maintained on the eastern side of the river for the duration of construction. Any required detours around construction work will be clearly signposted and maintained to an acceptable standard;

– Communication and signage to ensure pedestrians and cyclists are informed of changes to access to the Hutt River Trail;

– Communication and signage to inform users of Te Awa Kairangi/Hutt River of construction works affecting the bed and any flowing water that may pose navigation or safety risks to river users;

– Dust and noise management measures to be outlined within the CEMP to ensure dust and noise are appropriately managed.

9.9.3 Conclusion

Overall, with the implementation of the measures identified above, which are to be controlled through conditions of consent, the potential adverse social and recreation impacts can be mitigated to a satisfactory level. It is considered the ultimate benefits of the Project will far outweigh these impacts.


9.10 Network utilities

There are a large number of existing infrastructure networks throughout the Project area ranging from local service connections through to regionally significant road, rail, water, electricity and gas transmission infrastructure.

9.10.1 Existing network utilities

Existing network utilities found within the Project area, or with the potential to be affected by Project works, are identified in section 3.7.2 of this report.

9.10.2 Effects on network utilities

Given the scale of the Project, effects on network utility infrastructure are anticipated. This includes impacts from temporarily or permanently relocating existing network utilities and from construction activities.

The Project team has consulted with network utility operators to identify the location of utilities within the Project area and will continue to consult network utility operators about specific requirements related to relocation and/or protection of network utilities and to develop appropriate measures to manage adverse effects on network utilities during the construction and operation of the Project. There are well-established procedures across the industry for the relocation and/or protection of network utilities arising from construction activities.

9.10.3 Measures to avoid, remedy or mitigate adverse effects on network utilities

The general design philosophy adopted for the Project has been to avoid potential adverse effects on existing network utilities, wherever practicable. However, not all potential impacts can be avoided due to the large scale of the Project and the considerable number of network utilities located within the Project area needing to be re-located.

Consultation with relevant network utility providers has begun and through this consultation process design standards will be identified and the construction methodologies developed to minimise impacts on these utilities. These solutions typically involve one or more of the following approaches:

– Providing increased protection for the utility so that its operation is not adversely affected by the Project

– Providing access to the utility so that its operation and maintenance is not adversely affected by the Project

– Relocating or realigning part of the network utility to avoid or mitigate potential adverse effects, and

– Other specific measures (e.g. dust management) to address potential physical adverse effects on sensitive network utilities, such as transmission lines.

Consultation with affected operators will continue during detailed design to ensure that any relocation, diversion or protection of network utilities will meet the requirements of the operators.

9.10.4 Conclusion

Overall, any operational adverse effects on network utilities have been avoided or can be mitigated through design of the Project including planned relocation of utilities where required. Consultation with the network utility operators is underway. Any adverse effects during construction can be appropriately managed through measures which will be developed in consultation with the network utility operators.


9.11 Archaeology and heritage

An assessment has been undertaken by an appropriately qualified and experienced archaeologist to review the risk of archaeological sites in the vicinity of the Project works, as defined in the Heritage NZ Pouhere Taonga Act 2014. The Archaeology Assessment is provided in Appendix H.

The desktop assessment includes a review of the geomorphology of the area to determine whether there are older land surfaces that would have been suitable for pre-European or 19th century settlement. It indicates the presence of a 19th century railway, and a late 19th and early 20th century bridge in the general vicinity of the works. However, the assessment notes the proposed works either take place on dynamic low river terraces that have formed in recent decades, or within major road and rail corridors that have seen significant excavation and refurbishment over the years. The assessment therefore concludes it is unlikely that any pre-1900 road or rail fabric remains in situ within the proposed area of works.

There are known traditions of Māori use and occupation in the area, however there is no evidence for use of the specific area of proposed works. The likelihood that an unrecorded Māori archaeological site will be encountered in the specific area of works is assessed as low.

Overall, it was concluded that there is no reasonable cause to suspect that archaeological sites will be disturbed during the proposed works. Therefore, it is considered that no authority is required under the Heritage NZ Pouhere Taonga Act 2014 and there will be no adverse effects on archaeology or heritage values.


10 Measures to manage effects on the environment

10.1 Introduction

The assessment of effects on the environment in section 9 of this AEE identifies a range of positive and adverse, actual and potential effects from the construction and operation of the Project.

The consent design of the Project has sought to avoid adverse effects to the extent practicable through the iterative design and consideration of alternatives processes, which have been informed by numerous technical specialists, and the proposed construction methodology. The effects assessment has identified a range of potential adverse effects that cannot be avoided and require remediation or mitigation to appropriately manage adverse effects.

This section discusses the measures proposed and provides:

– The Project delivery framework, identifying how conditions and management plans will be implemented through the detailed design, construction and operational phases of the Project;

– Details of the management plans, the timing of their submission and duration and the approval mechanism for proposed management plans, and

– A summary of measures to manage adverse effects.

The mitigation, remediation and monitoring measures summarised in this section are reflected in the proposed conditions for the resource consents in Appendix M.

Key to the future management of effects is the development and implementation of a suite of measures, including management plans, monitoring and maintenance requirements, that are detailed in the conditions of consent. Collectively, these will form the Project delivery framework. This includes the need to manage areas of environmental sensitivity, to recognise environmental risk issues, and to identify the mechanisms to avoid, remedy or mitigate (and in some instances, offset) any actual and potential effects.

In addition to the resource management elements identified above, the applicant and their contractor will implement other mechanisms to manage the design, construction and operation of the Project. This includes documented procedures in project management plans, health and safety plans, works delivery documentation and management systems.

10.1.1 Proposed conditions

Based on the mitigation and monitoring measures summarised at the end of this section, a suite of resource consent conditions are proposed to ensure that the potential adverse effects that might arise from the construction, operation and maintenance of the Project will be appropriately avoided, remedied or mitigated. The proposed conditions address pre-construction requirements relevant to the detailed design process, management plans and monitoring as well as maintenance and the ongoing operation and maintenance of the Project. The proposed conditions are contained in Appendix M of this AEE.

10.1.2 Management plans and other information

Many of the potential effects of the Project are proposed to be managed through management plans and supporting site management and monitoring measures. These measures will be secured through the conditions


which will outline their information requirements and how they will be implemented. The majority of the management plans will be developed during the detailed design and pre-construction phases of the Project. When the management plans are submitted to the relevant regulatory authorities, they will reflect the final design and construction methodology for the Project. Table 28 below outlines which management plans will be submitted to which authority for certification or for information prior to construction.

The management plans that will be provided for information relate to matters that either are not the subject of a resource consent (e.g. communication and engagement measures); address matters of relevance to mana whenua, where mana whenua are best placed to determine the acceptability of the plan; or they are the subject of other council approval processes (e.g. the specific requirements of the road controlling authorities and network utility operators).

Each management plan will contain a Project-specific methodology for avoiding, remedying or mitigating the actual and potential adverse effects arising from the construction and/or operation of the Project, within the parameters set in the conditions. Management plans may be submitted in parts or in stages to address particular activities or to reflect the staged implementation of the Project.

Table 28 Management plans to submit to Council’s

Management Plan Approval mechanism Decision Pathway

Construction Environmental Management Plan (CEMP)

Certification GWRC HCC UHCC

Erosion and Sediment Control Plan (ESCP) Certification GWRC

For Information HCC UHCC

Dewatering Settlement Monitoring Plan (DSMP)

Certification GWRC

Ecological Management Plan (EMP), including sections on: – Vegetation Removal Management – Planting Establishment and

Management – Lizard Management – Avifauna Management – Aquatic Habitat Management

Certification GWRC HCC UHCC

Contaminated Land Management Plan (CLMP)

Certification HCC

Urban Design and Landscape Plan (UDLP) Certification HCC UHCC

For Information GWRC

The scope of each of the management plans, including the purpose of the plan and the proposed content is set out in the sections that follow.

10.1.2.1 Construction Environmental Management Plan (CEMP)

The CEMP sets out the measures to manage effects during construction. The purpose of the CEMP is to confirm the construction methods and management procedures used in order to avoid, remedy, mitigate potential adverse effects arising from construction activities. It will include the environmental management and monitoring procedures to be implemented during the Project’s construction phases and details of the 'how, who,


what, where and when' in respect of the environmental management and mitigation measures to be implemented.

The CEMP will be prepared with the input of the construction contractors and will be provided to Councils for certification prior to construction commencing. The CEMP will also clearly outline where other management plans are relevant for managing effects of construction during specific activities or within specific areas.

The CEMP shall include details of:

– Construction works programming;

– The final construction methodologies

– Site management measures;

– Staff and contractors’ responsibilities;

– Training requirements for employees, contractors, any sub-contractors and visitors;

– Environmental incident and emergency management;

– Environmental complaints management;

– Traffic management measures, including those for pedestrians and cyclists, during construction;

– Compliance monitoring;

– Corrective actions, if necessary, in specified circumstances (e.g. relating to wildlife management);

– Stakeholder and communication management.

The CEMP will be submitted to all regulatory authorities for certification and will be implemented during the duration of construction activities.

10.1.2.2 Erosion and Sediment Control Plan (ESCP)

The purpose of the ESCP is to set out the measures to be implemented during construction to minimise erosion and the discharge of sediment beyond the boundaries of the Project area. As a minimum, the ESCP will demonstrate how the requirements of the Erosion and Sediment Control Guidelines for the Wellington Region (2021) will be met.

The ESCP will also include consideration of chemical treatment methods, if they are required, outlining the specific design details for chemical treatment devices to be used on site, the dosage rates to be implemented for each device and how the performance of chemical treatment devices will be monitored.

10.1.2.3 Dewatering and Settlement Monitoring Plan (DSMP)

The DSMP will provide details on how dewatering activities will be managed to avoid, mitigate or remedy effects on ground and surface water, and potential effects of settlement, by including the following details:

– Duration, location, volume and rate of any dewatering required

– Quality of water to be discharged

– Effects of land subsidence

– Effects on surface water bodies and interference effects on any known lawfully existing water takes at the time of construction

– Groundwater level monitoring requirements and trigger levels,

– Location of monitoring pins/markers

– Contingency actions in the event trigger levels are exceeded;

– Reporting requirements


A draft DSMP has been prepared and is included as an appendix to the Assessment of Dewatering Effects (Appendix E). The final DSMP will be prepared in general accordance with this draft DSMP.

10.1.2.4 Ecological Management Plan (EMP)

The EMP will set out the specific procedures, methods and monitoring requirements required to be undertaken for the Project. It will include details of the mitigation and monitoring required for terrestrial fauna and flora (including avifauna) and aquatic fauna. The contents of the EMP is set out in the relevant draft consent conditions contained in Appendix M.

The EMP will include a number of sections related to the management of specified ecological communities during Project construction and operation. These sections include:

– Vegetation Removal Management

– Planting Establishment and Management Plan

– Lizard Management

– Avifauna Management

– Aquatic Habitat Management

The EMP will be submitted to GWRC, HCC and UHCC for certification and will be implemented for the duration of construction and associated post-construction monitoring of the effects of the Project.

10.1.2.5 Contaminated Land Management Plan (CLMP)

A CLMP will be prepared prior to excavation in areas known to be contaminated or potentially contaminated. The CLMP will be prepared in accordance with the requirements of the resource consents under the NESCS.

The purpose of the CLMP is to set out the procedures and methods to be implemented during construction to control the disturbance and movement of any identified contaminated, or potentially contaminated soils. The procedures focus on managing the health, safety and potential environmental risk from contaminated land associated with the Project. A draft CLMP has been prepared and is included as an appendix to the DSI (Appendix C) and the contents of the CLMP are set out in the relevant resource consent condition in Appendix M.

The CLMP will be submitted to HCC for certification and will be implemented during construction under the supervision of a Suitably Qualified and Experienced Practitioner.

10.1.2.6 Urban Design and Landscape Plan (UDLP)

A DLP will be prepared to integrate the Project’s permanent works into the surrounding cultural and environmental landscape and urban context and illustrate the cultural and environmental elements of the Project. The UDLP will also support the achievement of the objectives of the EMP through combining landscape planting with restoration planting and habitat rehabilitation where practicable.

A Landscape Concept has been prepared and is included as an appendix to the Assessment of Natural Character, Landscape and Visual Effects (Appendix G). The UDLP will be prepared having regard to this Landscape Concept.


11 Statutory assessment 11.1 Introduction

This section provides an assessment of the Project against the relevant statutory framework within which resource consents are sought. In particular, this section assesses the Project against the statutory requirements of sections 104(1)(b) RMA, 105 RMA, 107 RMA, and Part 2 of the RMA, being sections 5 to 8 of the RMA.

11.2 Assessment of relevant objectives and policies of planning documents

In the following sections, we provide an assessment of the Project against the relevant provisions of these planning documents:

– NES Soil (refer section 6)

– NES Freshwater (refer section 6)

– National Policy Statement for Freshwater Management;

– Regional Policy Statement for the Greater Wellington Region;

– Proposed Natural Resources Plan (appeals version dated 1 July 2021);

– Operative Regional Freshwater Plan for the Wellington Region;

– Operative Regional Plan for Discharges to Land for the Wellington Region;

– City of Lower Hutt District Plan; and

– Upper Hutt City Council District Plan.

The assessment of the relevant statutory planning documents in this section is supported by Appendix N. This section summarises how the Project fits with the applicable policy direction across the themes drawn from the planning documents listed. Appendix N sets out the full text of the relevant objectives and policies and groups them by key themes.

11.2.1 National Policy Statement for Freshwater Management

The Project involves temporary reshaping of the riverbed of Te Awa Kairangi/Hutt River within the Project area and earthworks and construction activities within the bed and within close proximity to the river, and as such, the NPSFM is relevant to the Project.

Policy 1 requires that freshwater is managed in a way that gives effect to Te Mana o te Wai. Te Mana o te Wai refers to the fundamental importance of water and recognises that protecting the health of freshwater protects the health and well-being of the wider environment. Te Mana o Te Wai seeks to protect the mauri of the wai (water) while restoring and preserving the balance between the water, the wider environment, and the community.

The six principles of Te Mana o te Wai inform the implementation of the NPSFM:

– Mana whakahaere: the power, authority, and obligations of tangata whenua to make decisions that maintain, protect, and sustain the health and well-being of, and their relationship with, freshwater.

– Kaitiakitanga: the obligation of tangata whenua to preserve, restore, enhance, and sustainably use freshwater for the benefit of present and future generations.

– Manaakitanga: the process by which tangata whenua show respect, generosity, and care for freshwater and for others.


– Governance: the responsibility of those with authority for making decisions about freshwater to do so in a way that prioritises the health and well-being of freshwater now and into the future.

– Stewardship: the obligation of all New Zealanders to manage freshwater in a way that ensures it sustains present and future generations.

– Care and respect: the responsibility of all New Zealanders to care for freshwater in providing for the health of the nation

Te Mana o te Wai also includes a hierarchy of obligations that prioritises:

– first, the health and well-being of water bodies and freshwater ecosystems

– second, the health needs of people (such as drinking water)

– third, the ability of people and communities to provide for their social, economic, and cultural well-being, now and in the future

These principles have been considered in the design and consenting approach for the Project, which seeks to provide holistic consideration of the effects of the Project on freshwater with the objective to maintain, and where possible, enhance the mana and mauri of Te Awa Kairangi/Hutt River.

The Project has been developed to respond to the history of, and current pressures, on water supply infrastructure as a result of hazards attributed to Te Awa Kairangi/Hutt River and earthquakes, while having regard to the integrated approach to freshwater management and land use to avoid adverse effects (including cumulative effects) on the health and well-being of freshwater environments. A suite of technical assessments have been undertaken to assess the effects of the Project, these assessments have been undertaken in an integrated manner, taking into account potential effects on the freshwater receiving environments.

Policy 2 requires that tangata whenua are actively involved in freshwater management (including decision making processes), and that Māori freshwater values are identified and provided for. The applicant has worked in partnership with Taranaki Whanui during the development of the Project and is committed to maintaining this partnership and working alongside Mana Whenua throughout the Project’s construction and operation. This is reflected through the Position Statement prepared by Taranaki Whānui with respect to the Project and the applicant’s engagement efforts with Ngāti Toa to date. Ngāti Toa will have the opportunity to provide feedback during the submission process, ensuring their role in the decision making process is maintained.

Policy 3 of the NPSFM requires freshwater to be managed in an integrated, whole of catchment approach. The development of the Project followed an integrated process, by which the interrelationships of various aspects of the Project and its effects were considered in the design of the Project with effects on the receiving environment (at a catchment scale) including Te Awa Kairangi/Hutt River and the groundwater system considered by technical experts.

Policy 4 requires freshwater to be managed as part of New Zealand’s integrated response to climate change. The severity and frequency of flood events is only expected to increase with climate change. The Project seeks to provide resilience to the effects of climate change by minimising the effects of flooding on regionally significant water supply infrastructure.

Policies 7, 8 and 9 require that the loss of river extent and values is avoided to the extent practicable, the significant values of outstanding water bodies are protected, and the habitats of indigenous freshwater species are protected, respectively. The Project avoids the loss of river extent and the significant biodiversity, and natural character, values will be maintained and where possible enhanced. As a result, the habitats of indigenous freshwater species will be appropriately protected.

While the affected reach of Te Awa Kairangi/Hutt River is not identified as an outstanding water body (with reference to Policy 8), as set out in the Ecology Assessment, the Project will have effects on the values of Te Awa


Kairangi/Hutt River and an unnamed tributary, particularly water quality and consequential effects on aquatic habitat and freshwater species in the downstream receiving environment during construction. Measures are proposed to minimise these effects to the extent practicable, including fish salvage and recovery prior to in-stream works, erosion and sediment controls and a carefully considered construction methodology which avoids works in flowing water to the extent practicable. With the above measures in place, habitats of indigenous freshwater species will be protected and the impact on river values will be minimised to the extent practicable.

Policy 10 requires the habitat of trout and salmon to be protected so long as this does not compromise the protection of indigenous freshwater habitats. Te Awa Kairangi/Hutt River provides habitat to trout and is a popular river for trout fishing, and this has been considered in the Project design and construction methodology. Minimising effects on freshwater habitat, including habitat for trout and migration of trout to upstream habitat, has informed the design and construction methodology, particularly the construction phasing and approach to avoiding works in the active channel. Any construction related effects on trout will be limited in extent and duration during construction activities (temporary) and there will be no long-term effects on trout habitat or populations.

Policy 15 relates to enabling communities to provide for their social, economic, and cultural wellbeing in a way that is consistent with this NPSFM. The Project will increase the resilience of the water supply network and will allow the community to enjoy the river and the river trail more, including by providing access to areas of the river corridor that was previously not accessible. The Project is therefore highly enabling of social, economic and cultural benefits for the surrounding communities.

11.2.1.1 Specific clauses of the NPSFM

Two specific clauses of the NPSFM, particularly relevant to consideration of the effects of the Project, have been considered as if they are already operative in a regional plan. These are assessed below.

3.24 Rivers

“The loss of river extent and values is avoided, unless the council is satisfied:

(a) that there is a functional need for the activity in that location; and

(b) the effects of the activity are managed by applying the effects management hierarchy”

The Project will not require the loss of river extent and as outlined in the Ecological Assessment (Appendix F) and Assessment of Natural Character, Landscape and Visual Effects (Appendix G) the values of the significant biodiversity and natural character values the river supports will be maintained.

3.26 Fish passage

“The passage of fish is maintained, or is improved, by instream structures, except where it is desirable to prevent the passage of some fish species in order to protect desired fish species, their life stages, or their habitats.”

The Project has had careful regard to the maintenance and improvement of fish passage. It is noted that there is an existing fish passage barrier in the unnamed tributary at the existing access track culvert. The Project is not undertaking any works to this access track or culvert and therefore this fish passage barrier will remain. A permanent crossing of the unnamed tributary for maintenance is required as part of the Project. Design work has determined that a weir/ford crossing is the most appropriate design solution in order to ensure that fish passage at this location can be maintained. Although fish passage is currently restricted, the Project design ensures that fish passage is not precluded, should existing fish passage barriers upstream and downstream of the weir/ford be removed, and fish passage becomes possible in the future.

In conclusion, the Project is consistent with the NPSFM.


11.2.2 Regional Policy Statement for the Wellington Region

The Regional Policy Statement for the Wellington Region (2013) is a document prepared under the Resource Management Act 1991 that identifies the major resource management issues for the Wellington region. The RPS sets an over-arching framework for resource management issues in the region, with the detailed policy direction provided through the regional and district plans. As such, while an assessment of the Project against the RPS has been undertaken, to a large extent, the key policy direction which is relevant to the Project is provided by the regional and district plans. An assessment of relevant objectives and policies of the RPS is set out in Table 29.

Table 29 Regional Policy Statement objectives and policies assessment

Theme Relevant objectives and policies

Comment

Regionally significant infrastructure and network utilities

Objective 10 Policy 39

The RPS requires the social, economic, cultural and environmental benefits of regionally significant infrastructure to be recognised and protected, by having particular regard to these benefits and protecting Regionally Significant Infrastructure (RSI) from incompatible use and development. The Kaitoke main is considered RSI and the replacement of this RSI is therefore considered generally appropriate. In respect of potential reverse sensitivity effects on existing RSI, the Project will involve works within the rail corridor and disruption to SH 2 in discrete sections. The underground infrastructure also requires re-alignment and relocation of existing network utility services, some of which are RSI. The Project will continue to work with affected network utility providers to minimise disruption and allow for the continued safe and efficient operation of network utilities during construction and in the long term.

Development form, design and function

Objective 22 Policy 57 Policy 58

Policy 54 of the RPS requires particular regard to be given to the region’s urban design principles. Although not an urban design Project, elements of the Project such as the bridge, will include urban design elements. Urban design has and will continue to be a key focus for the Project as the bridge design is developed and refined. The RPS seeks the integration of land use planning, infrastructure and transport; and the provision and use of infrastructure in a way that is efficient and safe, and co-ordinated with the development and operation of new infrastructure (Policy 57 and 58).

The Project provides an opportunity to improve safety, connectivity and accessibility to the existing cyclist and pedestrian network in the Hutt River corridor, and as such is consistent with the direction in the RPS.

Māori relationships and cultural effects

Objective 23 Objective 24 Objective 25 Objective 26 Objective 27 Objective 28 Policy 48 Policy 49

The RPS requires the principles of the Treaty of Waitangi to be taken into account and recognition and provision for matters of significance to tangata whenua. Recognition of the role of tangata whenua as kaitiaki and provision for tangata whenua involvement in management of natural resources has been achieved for this Project through the recognition of the connection Mana Whenua have to the Te Awa Kairangi/Hutt River environment as reflected in the Position Statement prepared by Taranaki Whānui. Following discussion with Ngāti Toa in earlier phases of the Project, the applicant has made numerous efforts to further engage with Ngāti Toa, however have not received any further formal response to date. As part of the partnership agreement with Ngāti Toa the applicant will continue to consult with Ngāti Toa throughout the consenting, detailed design and construction phases of the Project. The Project has ensured, through the relationship with Taranaki Whānui and the provision for ongoing involvement and recommended mitigation secured through conditions of consent, that it will facilitate the protection of the relationship of Taranaki Whānui with the historic, traditional, cultural and spiritual elements of Te Awa Kairangi/Hutt River and supporting freshwater and terrestrial ecosystems. Ngāti Toa will be able to make a submission reflecting any concerns or opinions they have regarding the Project during the notification period of this consent application, ensuring that their role as kaitiaki is maintained. Adverse effects on indigenous biodiversity values have been appropriately avoided or mitigated where there is the potential for a reduction in historical, cultural or spiritual



Comment

association held by Mana Whenua with Te Awa Kairangi/Hutt River. Indigenous biodiversity values and the spiritual connection of Mana Whenua to their land and waters are to be enhanced through providing for the role of Mana Whenua as kaitiaki and through the practical exercise of kaitiakitanga in restoring and enhancing the river margins post-construction.

Natural character and recreation amenity values (including public access)

Objective 8 Objective 18 Policy 53

The RPS seeks to maintain and enhance public access to rivers with indigenous ecosystems and habitats and areas with special amenity and significant historic heritage values. Te Awa Kairangi/Hutt River has been identified as supporting indigenous ecosystems and the Project will enhance physical and visual access to the river corridor at this location. Observation platforms on the bridge deck and pedestrian/cycle access across the river suitable for all levels of mobility will improve the connection between the community and the river. Access to the river corridor will be restricted in some locations during construction to protect and encourage biodiversity and to protect health and safety of the public, however these restrictions will be temporary.

Heritage Objective 15 Policy 46

Objective 15 and Policy 46 of the RPS seek to identify and protect heritage values, including consideration of the potential effects on heritage places, sites and areas. Policy 46 provides direction on matters to consider to determine if an activity which affects heritage values is inappropriate. There are no archaeological or historic heritage sites within the proposed Project footprint which have been assessed as having some historic heritage value. However, there is potential for unrecorded archaeological sites to be located during excavation of the riverbed and banks. This will be managed through an accidental discovery protocol. Overall, construction will have no effects on known archaeological and historic heritage sites and/or values, and little potential for effects on unrecorded subsurface sites.

Natural hazards Objective 19 Objective 20 Objective 21 Policy 51 Policy 52

The RPS seeks to ensure that new development (including infrastructure) is located and designed to manage the impacts from natural hazards that may be experienced over their lifetime, that hazard mitigation works do not increase the risk and consequence of natural hazard events and that communities are more resilient to, and better prepared for, the consequences of natural hazards. The Project, in particular the pipe bridge, has been designed in accordance with the most up to date design standards, including the HRFMP and the Bridge Manual. The Project has been assessed to have a negligible impact on downstream flooding or erosion within the buffer zone. The design has also considered fault rupture, ground shaking, lateral spreading, regional uplift/subsidence and slope instability. These risks are generally unavoidable and can be mitigated to the extent practicable through engineering design. The Project does not cause or exacerbate ground hazards in other areas. As such, the Project is consistent with the hazard direction in the RPS.

Water quality Objective 12 Objective 13 Objective 29 Policy 40 Policy 41 Policy 42

The relevant objectives and policies of the RPS seek to manage freshwater quality to meet the range of uses and values for which freshwater is required, safeguard the life capacity of waterbodies and meet the needs of future generations by minimising the effects of earthworks and vegetation disturbance. As described in section 9.3.4 of this AEE, best practicable options will be adopted for construction water management and treatment. Earthworks and land disturbance will be managed to avoid, remedy or mitigate the potential effects of erosion and sediment discharges to the receiving environment. Land disturbance will be managed to retain soil and sediment on the land by implementing best practicable options for sediment and erosion control. Mechanisms will be implemented to manage effects of sediment generation such as stabilisation requirements and refining the construction sequencing and programme to minimise the risk and severity of discharges.



Comment

As a result, any changes in water quality associated with the Project are expected to be minor, and as such the Project is considered to be consistent with the RPS direction in relation to water quality.

Biodiversity and ecology

Objective 13 Objective 16 Policy 43 Policy 47

The RPS indigenous biodiversity objectives seek to ensure rivers support healthy functioning ecosystems and indigenous ecosystems and habitats with significant biodiversity values are maintained and restored. Policies seek to protect aquatic ecological function and to manage effects on areas with significant biodiversity values. As described in Section 7, a comprehensive alternatives assessment was undertaken, which sought to avoid or remedy effects on environmental values. Where this was not practicable, measures have been proposed to remedy effects on these values. In particular, the Project seeks to avoid works in flowing water to the extent practicable and restoration and enhancement of riparian margins to improve the opportunities and habitat available for biodiversity over-time, are proposed to protect ecological values and manage effects. The Project is considered to be consistent with the RPS direction on biodiversity and ecological values.

Take use and diversion of water

Objective 14 The RPS requires that freshwater is allocated and used efficiently. Temporary damming and diversion of Te Awa Kairangi/Hutt River if required during construction will not result in any water being diverted outside of the river system (no diversion outside of the river bed). In addition, any flow diverted during construction in the unnamed tributary will be returned to the unnamed tributary. Therefore, minimum flows and water levels will not be impacted. As such, the Project will efficiently use surface water and is consistent with the direction of the RPS.

General Amenity effects

Objective 1 Objective 2

The RPS requires discharges of odour, dust and smoke to avoid adversely affecting amenity and people’s wellbeing, and also requires that human health is protected from fine particulate matter. Discharges of dust to air as a result of earthworks and construction activities may occur. These discharges will be managed through best practice site management and specific mitigation measures during construction. With mitigation measures in place, potential offensive and objectionable effects on human health, property and the environment are not anticipated beyond the boundary of the construction site. The Project is therefore considered consistent with the relevant objectives and policies of the RPS.

11.2.3 Operative Regional Freshwater Plan for the Wellington Region

The Regional Freshwater Plan (RFP) is the operative plan in the Wellington Region for managing freshwater issues, including water quality and quantity. A summary assessment of this regional plan is provided in Table 30 below.

Table 30 Regional Freshwater Plan objectives and policies assessment


Comment

Integrated Management

Policy 4.2.30 Policy 4.2.31

The RFP seeks to provide for appropriate involvement of tangata whenua, people and communities in freshwater management decision making and to provide for integrated management of freshwater resources. Consultation with people and communities has been ongoing, with the Project signalled in the LTP66 enabling the public and stakeholders to be involved in decision-making. In this regard, a publicly notified consent process has been sought to enable the public and stakeholders the opportunity to have their say and so that effects of use and development across the jurisdictional boundaries

66 GWRC 2021-31 Long Term Plan, pg.93, 154



Comment

can be considered holistically in an integrated manner (Objective 4.1.15 and Policies 4.2.30 and 4.2.31). The RFP also requires a precautionary approach to freshwater where information is incomplete or limited. In the case of this Project, it is considered that there is adequate information on the potential effects on freshwater, such that a precautionary approach is not relevant.


Objective 4.1.1 Objective 4.1.2 Objective 4.1.3 Objective 4.1.15 Objective 5.1.3 Policy 4.2.1 Policy 4.2.2 Policy 4.2.3 Policy 4.2.4 Policy 4.2.5 Policy 4.2.6 Policy 4.2.7 Policy 4.2.8 Objective 7.1.4

The RFP requires recognition of the Treaty of Waitangi and tangata whenua values. The Project has recognised and provided for the relationship of tangata whenua with taonga, ancestral sites (4.1.1) through engagement with Taranaki Whānui and with Ngāti Toa. Taranaki Whanui prepared a position statement. The Project proposes through conditions of consent to protect the mauri and quality of water (Objectives 4.1.2 and 5.1.3), and ensure cultural values are not adversely affected, access to Te Awa Kairangi is retained and effects on habitats of species harvested by tangata whenua are minimised and mitigated (Objectives 4.2.1, 4.2.3 and 4.2.4). The applicant has made numerous attempts to obtain the feedback of Ngāti Toa with no formal response from Ngāti Toa received to date. As part of the partnership agreement between Ngāti Toa and the applicant the applicant will continue to consult with Ngāti Toa during the consenting, detailed design and construction phases of the Project. In addition, Ngāti Toa will be able to make a submission reflecting any concerns or opinions they have regarding the Project during the notification period of this consent application. Ngāti Toa will therefore have the ability to be involved in decision making on freshwater management issues (Objective 4.1.15). Recognition of the role of tangata whenua as kaitiaki and provision for tangata whenua involvement in management of natural resources has been achieved for this Project through the recognition of Mana Whenua as kaitiaki, in particular through recognition of the unique cultural and spiritual connection of Mana Whenua to Te Awa Kairangi/Hutt River consistent with the respective statutory acknowledgements. The Project has ensured, through the relationship with Mana Whenua and involvement and support of Mana Whenua and adoption of the recommended measures to mitigate adverse effects on ecological values and to enable cultural expression through design features, that it will facilitate the protection of the relationship of iwi with the historic, traditional, cultural and spiritual elements of Te Awa Kairangi/Hutt River and supporting ecosystems. This is consistent with Policies 4.2.2, 4.2.5, 4.2.6 and 4.2.7.

Natural character and recreational amenity values (including public access)

Objective 4.1.4 Objective 4.1.7 Objective 4.1.8 Policy 4.2.9 Policy 4.2.15 Policy 4.2.17 Policy 5.2.4

The RFP seeks to preserve and protect natural character; and maintain (and enhance) access, recreational values, and amenity of wetlands, rivers and lakes. During the construction of the Project there will be a temporary effect on access, natural character and amenity. To minimise these effects to the extent practicable, the works will be staged, reducing the extent of river and land affected at any one time minimising effects on natural character (Objectives 4.1.4, 4.1.8 and 4.2.15). The design and construction methodology have had regard to minimising effects on ecosystems, habitats, species and water quality (4.2.9). The Project will result in enhanced access to the river corridor, and provide public access to an area of the river corridor that is not currently accessible to the public, this will enhance recreational values alongside the river margins, consistent with Policy 4.2.17. Natural character will be preserved with opportunities for further enhancement through habitat restoration. Landscape values will also be improved through native riparian and landscape planting (Objective 4.1.7). The Project is therefore consistent with the policy direction in the RFP regarding natural character



Comment

Natural hazards Objective 4.1.9 Objective 4.1.10 Policy 4.2.18 Objective 7.1.2 Objective 7.1.3 Policy 7.2.3 Policy 7.2.6 Policy 7.2.7

The RFP seeks to manage the risk of flooding to health and safety, natural values, physical resources and property to an acceptable level. New development (including infrastructure) is required to be located and designed to manage the impacts from flooding that may be experienced over their lifetime (Objectives 4.1.9 and 4.1.10). The RFP allows development of new structures within the river bed provided that they do not contribute to flood risk and do not damage flood mitigation works (Objectives 7.1.2 and 7.1.3). The Project will improve the resilience of RSI in the face of natural hazard risks that are deemed unacceptable due to the potential consequences on the community. Predicted changes in climate, which are predicated to exacerbate natural hazard (in particular flooding) effects, have been taken into account in the design of the bridge. Best available and up-to-date hazard information across a range of probabilities was used to inform the design in the face of flooding as consistent with Policy 7.2.6. The Project will not have any significant effects on flood risk or natural values (Policy 7.2.3) and will avoid adverse effects on the integrity of flood mitigation works 7.2.7). The Project, including its structures and earthworks activities, has been designed to improve the resilience of RSI in flooding events and otherwise minimise the flood risk and adverse effects to people and property as a result of new structures in the river and floodplain (Policy 4.2.18).

Water quality Objective 4.1.5 Policy 4.2.27 Objective 5.1.1 Objective 5.1.2 Policy 5.2.3 Policy 5.2.4 Policy 5.2.6 Policy 5.2.8 Policy 5.2.10 Policy 5.2.13 Policy 5.2.15

The RFP seeks to safeguard the life-supporting capacity of water and aquatic ecosystems, manage water quality for ecosystem health purposes and contact recreation and to meet the needs of future generations, and encourages discharges to land and treatment of discharges to reduce adverse effects (Objectives 4.1.5, 5.1.1, 5.1.2 and Policies 5.2.3, 5.2.4 5.2.6 and 5.2.13). The Project will utilise best practice techniques during construction to manage sediment, which is predicted to result in a negligible change in the downstream receiving environment, when considered in conjunction with the existing sediment/water quality within Te Awa Kairangi/Hutt River. As discharges during construction are temporary and where possible discharged to land, the proposal is consistent with Policies 5.2.8, 5.2.10 and 5.2.13. With the proposed measures in place to manage adverse effects on freshwater quality from discharges of sediment and other construction contaminants, any potential effects on freshwater and associated ecosystems will be minimised such that they are consistent with the policy framework of the RFP.

Biodiversity and ecology Objective 4.1.5 Objective 4.1.6 Policy 4.2.11 Policy 4.2.12 Policy 4.2.14 Policy 5.2.3 Policy 5.2.6 Policy 7.2.11 Policy 7.2.14

Key provisions of the RFP include objectives 4.1.5 and 4.1.6 which require that the life supporting capacity of freshwater is safeguarded and significant aquatic vegetation and habitats of freshwater fauna are protected. These objectives are given effect to through Policy 4.2.11 which requires activities to avoid, remedy and mitigate adverse effects which affect aquatic ecosystems and habitats, Policy 4.2.14 which requires activities to avoid, remedy and mitigate effects on identified important trout habitat and Policy 7.2.11 which seeks to ensure that the use of river beds not covered by water does not disturb nesting birds. Policy 4.2.33 provides for activities with no more than minor effects. The Project includes works with no significant or prolonged decreases in water quality, no anticipated adverse effects on mahinga kai or waahi tapu. Any adverse effects on plants, animals and habitats will be temporary and minimised to the extent practicable. The Project will be consistent with the relevant provisions of the RFP. A range of measures are proposed to minimise the potential effects of the Project on ecological values including restoration planting, erosion and sediment controls, salvage of indigenous fauna and flora prior to construction where practicable (Policies 5.2.3, 5.2.6 and 7.2.14) and replanting following completion of the works. The Ecology Assessment has determined that the effects of the Project on freshwater ecology values will be, at worst, minor.



Comment

Activities within the bed of rivers

Policy 4.2.33 Objective 7.1.1 Policy 7.2.1 Policy 7.2.2 Policy 7.2.12

Policy 4.2.33 provides for activities with no more than minor effects and includes criteria for determining whether an activity will have no more than minor effects. As outlined in section 9 of this report, the Project is expected to meet all of the criteria listed in Policy 4.2.33. The RFP allows for specified uses within river beds where adverse effects are avoided, remedied or mitigated and significant adverse effects are avoided (Objective 7.1.1 and Policy 7.2.1). The Project works within Te Awa Kairangi/Hutt River and the unnamed tributary are specified uses in the RFP – namely structures for network utility purposes; and structures for activities which need to be located in, on, under, or over the beds of rivers and lakes. The effects of these works are assessed in the Ecological Effects Assessment (Appendix F). Effects will be appropriately avoided, remedied and mitigated and there are not expected to be any significant adverse effects (Policy 7.2.2). The removal of vegetation will not exacerbate bank erosion or the flood hazard and will be subject to the proposed consents sought in this AEE.

Take, use and diversion of water

Objective 6.1.1 Objective 6.1.2 Objective 6.1.4 Policy 6.2.7 Policy 6.2.8 Policy 6.2.14 Policy 6.2.15 Policy 6.2.17

The RFP requires maintenance of water levels and flow regimes in water bodies to protect their natural, cultural and amenity values (Objectives 6.1.1 and 6.1.2). The Project will not have any adverse effects on nearby ground water users and will not result in significant adverse effects on surface water (Policy 6.2.8). Policy 6.2.15 provides for the temporary damming or diversion of a river where adverse effects are avoided, remedied or mitigated. Temporary damming and diversion of Te Awa Kairangi during construction will be undertaken within the river channel (no diversion outside of the river) and flow diverted in the unnamed tributary will be returned to the unnamed tributary downstream of the diversion. The RFP allows for the take of groundwater where it will not adversely affect groundwater quality or quantity or impact on takes from surrounding bores. To ensure that groundwater and nearby buildings and infrastructure are appropriately protected during construction, a DSMP has been developed to protect nearby groundwater users, buildings and infrastructure. This will ensure the Project is consistent with the direction in the RFP in relation to groundwater (Policy 6.2.17).

11.2.4 Operative Regional Plan for Discharges to Land for the Wellington Region

While not strictly required given the proposal does not require consents under the Regional Plan for Discharges to Land (RPDL) because the Project area does not meet the definition of a contaminated site, an assessment of the relevant objectives and policies has been included for completeness.

The RPDL is the operative plan in the Wellington region addressing discharges to land. This plan contains objectives and policies which are relevant to the Project, including Objectives 4.1.10 and 4.1.11, and Policies 4.2.46, 4.2.47, 4.2.48 and 4.2.49. In summary, the RPDL seeks to protect land and water resources through identification, management and remediation of land that is contaminated and to avoid creation of new contaminated land through management of discharges from contaminated land.

Any residual contamination risk will be appropriately managed through a Contaminated Land Management Plan (CLMP) which will include site-specific control measures as necessary for the construction phase. The Project is consistent with the objectives and policies in the outcomes sought in the RPDL.

11.2.5 City of Lower Hutt District Plan

The relevant objectives and policies of the HCC DP are assessed Table 31 below.


Table 31 HCC DP objectives and policies assessment


Comment


13.1.1 Objective & Policy (b) 13.1.2 Objective & Policy (a) 13.1.3 Objective & Policy (a) – (c) 13.1.4 Objective & Policy (a) – (f)

The objectives and policies of Chapter 13 of the HCC DP seek to recognise and protect the local benefits of Regionally Significant Infrastructure (RSI) and ensure that RSI and network utilities are not compromised by other activities. This includes avoiding, remedying and mitigating adverse effects on RSI and network utilities as a result of new use and development. In addition, the provisions seek to manage adverse effects on the environment as a result of the location, operation and maintenance of network utilities. The Project has been designed to comply with relevant National Environmental Standards and to meet other nationally recognised standards and guidelines and provides an opportunity for additional infrastructure to be supported by the bridge in future. The water supply network is defined as regionally significant infrastructure. The proposed works are required to increase the resilience of the water supply network and maintain existing levels of service for Porirua and areas of Wellington. As identified in Section 9 of this AEE effects of the construction of the Project can be appropriately avoided, remedied or mitigated. GWRC Flood Protection and KiwiRail, and Waka Kotahi and UHCC as RCA, have been consulted about the proposal, including the design and anticipated construction related effects. The pipeline will be underground except where it crosses Te Awa Kairangi/Hutt River, where underground placement was considered and deemed an unsuitable technical option due to the increase earthquake risk in this location. The Project is therefore consistent with the policy direction for enabling new RSI and protecting existing network utilities from reverse sensitivity effects.


14A 3.1 Objective 14A 4.1 Policy 14A 4.2 Policy 14A 4.6 Policy 14A 4.7 Policy

The HCC DP’s objectives include the provision of a safe, efficient, resilient and well-connected transport network that is integrated with land use patterns, facilitates and enables urban growth and economic development and meets local and regional needs; and provides for all modes of transport. The Project will contribute to achieving these objectives by providing an opportunity for better integration with the Hutt River trail and existing and planned pedestrian and cycle networks (Objective 14A 3.1). The effects of constructing and operating the bridge, which includes improved, pedestrian and cyclist access, will be appropriately avoided, remedied and mitigated through the design process and construction management as secured by conditions of consent. The Project will provide an opportunity to improve the safety and resilience of the pedestrian and cycle network, and will contribute to meeting the transport needs of the local community, of Lower and Upper Hutt communities and of GWRC.


14E 1.1 Objective & Policy (b) and (c) 14I 1.2 Objective & Policy (d)

The HCC DP provisions seek to identify and protect significant natural, cultural and archaeological resources and values in Lower Hutt from use or development that is inappropriate. The HCC DP recognises that new cultural and archaeological resources may be uncovered generally (14E 1.1(b)) or specifically through earthworks (14I 1.2(d)). There are no cultural or archaeological resources within or adjacent to the Project footprint, but the Project has put in place an accidental discovery protocol to assist with any accidental finds.


7A 1.1.4 Objective & Policy 7A 1.2.1 Objective & Policy (b), (d), (f) 7C 1.2.1 Objective & Policy (a), (b), (d), (e)

Chapter 7A related to the General Recreation Activity Area seeks to restrict the range and nature of non-recreational activities, ensure that the design and external appearance of structures maintains and enhances amenity values of recreation and open space areas and to encourage the multi-utilisation of buildings and structures. Chapter 7C seeks to control the external appearance of structures and maintain and enhance public access to the river. The draft Landscape Plans and the UDLP, to be secured by conditions of consent, provide the opportunity for urban design consideration of all structures to be constructed



Comment

within the river corridor. Whilst the Project will result in a temporary disruption to access to Te Awa Kairangi/Hutt River during the construction period, the Project will result in a significant improvement in amenity values and open space. The Project achieves this through the provision of improved cyclist and pedestrian access across the river and restoration planting which provides improved amenity for the community and improved habitat for wildlife. The Project is consistent with the objectives and policies of Chapter 7A and 7C of the HCC DP.

Heritage 14E 1.1 Objective & Policy (b) and (c) 14I 1.2 Objective & Policy (d)

The HCC DP provisions seek to identify and protect significant natural, cultural and archaeological resources and values in Lower Hutt from use or development that is inappropriate. The HCC DP recognises that new cultural and archaeological resources may be uncovered generally (14E 1.1(b)) or specifically through earthworks (14I 1.2(d)). There are no cultural or archaeological resources within or adjacent to the Project footprint, but the Project has put in place an accidental discovery protocol to assist with any accidental finds.

Natural Hazards 7A 1.2.2 Objective & Policy (b) 7C 1.1.3 Objective (b) & Policy (e) 7C 1.2.1 Objective & Policy (e) 14H 1.1.1 Objective & Policy (a) – (d)

The HCC DP seeks to avoid or reduce the risk of adverse effects of natural hazards on people and property and to manage new buildings and structures in the primary and secondary river corridors. Chapter 7C requires that the flood carrying capacity of the river channel and margins is not reduced and that structures are sited to avoid increasing flood risk. The Hydraulic Assessment concludes that there will be a negligible increase on flood levels in the river channel and downstream as a result of the Project. The Project will have no more than minor effects on flood protection structures. The Project is required to improve the resilience of regionally significant infrastructure from natural hazard risks that are deemed unacceptable due to the potential consequences to the community. Predicted changes in climate, which are likely to exacerbate flooding effects, have been taken into account in the bridge design. Best available and up-to-date hazard information across a range of probabilities was used to ensure that the flooding risk associated with the Project is understood and was not increased. The Project, including its structures and earthworks activities, has been designed to improve flood protection/resilience and otherwise minimise the flood risk and adverse effects to people and property. With regard to other natural hazards the Project straddles the Wellington Fault and will be designed to manage risk of seismic activity, slope stability, and settlement in accordance with the Bridge Manual. Where required, structural controls will be implemented through design to mitigate any residual land instability or seismic risks. The Project is consistent with the objectives and policies of the HCC DP relating to natural hazards and flooding.

General Amenity Effects 14C 1.1 Objective & Policy (f), (g)

The HCC DP seeks to maintain or enhance amenity values in all activity areas by avoiding or mitigating the adverse effects of excessive noise. In relation to the Project this applies during construction activities. As outlined in section 9.2.3.2 compliance with applicable construction noise is expected during construction activities. The Project will meet the relevant rules in the HCC DP related to noise and the noise objectives and policies of the HCC DP are therefore not relevant.

11.2.6 City of Upper Hutt District Plan

The relevant objectives and policies of the UHCC DP are assessed Table 32 below.


Table 32 UHCC DP objectives and policies assessment


Comment


Objective 16.3.1 Objective 16.3.3 Objective 16.3.4 Policy 16.4.2 Policy 16.4.3 Policy 16.4.5 Policy 16.4.8 Policy 16.4.9 Policy 16.4.10 Policy 16.4.12 Policy 16.4.13 Policy 16.4.14 Policy 16.4.15 Policy 16.4.16 Policy 16.4.17

The objectives and policies of Chapter 16 of the UHCC DP seek to recognise and protect the benefits of regionally significant infrastructure (RSI) and network utilities and ensure that RSI and network utilities are not compromised by other activities. This includes avoiding, remedying and mitigating adverse effects on RSI and network utilities as a result of new use and development. In addition, the provisions seek to manage adverse effects on the environment as a result of the location, operation and maintenance of network utilities. The Project co-locates transport (by providing pedestrian/cycle access across the bridge) and utilities, provides the opportunity for additional utilities infrastructure in future; . The Project will also improve connectivity between existing and planned pedestrian and cycling networks. Adverse effects of the proposal on the environment have been avoided to the extent practicable. Those effects which cannot be avoided have been remedied and mitigated as outlined in Section 9.3.4.. In respect of potential reverse sensitivity effects on existing RSI, works are required in the rail corridor and discrete areas of SH 2 and relocation or realignment of network utility services, some of which are RSI, will be required. The applicant will continue to work with affected network utility providers to minimise disruption and allow for the continued safe and efficient operation of network utilities during construction and in the long term. The Project has been designed to comply with relevant national environmental standards and to meet other nationally recognised standards and guidelines and provides an opportunity for additional infrastructure to be supported by the bridge in future. The pipeline will be underground except where it crosses the river. The assessment of alternatives outlines why placement of the pipeline under the river was impracticable and why the proposed design and location of the pipe bridge and pipeline are the most appropriate. The community have had visibility of the Project through the LTP process for GWRC and strategic reports which have identified the urgency of the Project to respond to concerns about resilience (as discussed in section 2 of this AEE). The community will have further opportunity to comment on the Project through the public notification process, which has been sought to ensure the community is able to input into the decision making process.


Objective 16.3.3 Policy 16.4.4 Policy 16.4.5 Policy 16.4.6

The Project will provide an opportunity for better integration with the Hutt River Trail and both existing and planned pedestrian and cycle networks. The effects of constructing and operating the bridge, which includes improved, pedestrian and cyclist access will be appropriately avoided, remedied and mitigated through the design process and construction management as secured by conditions of consent. Overall, the Project will provide an opportunity to improve the safety and resilience of the pedestrian and cycle network and will contribute to meeting Upper Hutt’s transport needs


Objective 11.3.2 Policy 11.4.2 Policy 11.4.3 Policy 11.4.4

When developing natural and physical resources the UHCC DP requires regard to be had for the Treaty of Waitangi principles, in particular recognition of the role of tangata whenua as kaitiaki. Provision for tangata whenua involvement in management of resources has been achieved for this Project through the recognition of the unique cultural and spiritual connection to Te Awa Kairangi/Hutt River. A Position Statement has been prepared between the applicant and Taranaki Whānui. The Position Statement identifies the relationships of Taranaki Whānui to the whenua and awa, and provides recommendations for mitigating effects on cultural values. The Position Statement requires that consultation shall continue during the design process, development of



Comment

management plans and through collaboration on conditions of consent providing opportunity to deepen human, spiritual and cultural connection with the river environment. Taranaki Whānui have been involved in the assessment of alternatives process and further opportunity exists for kaitiakitanga and partnership through input into the development of management plans and design of approach gateway features and interpretive signage, secured by the UDLP process and conditions of consent. The applicant has made numerous attempts to obtain the feedback of Ngāti Toa with no formal response from Ngāti Toa received to date. As part of the partnership agreement between Ngāti Toa and the applicant the applicant will continue to consult with Ngāti Toa during the consenting, detailed design and construction phases of the Project. In addition, Ngāti Toa will be able to make a submission reflecting any concerns or opinions they have regarding the Project during the notification period of this consent application. The proposal is consistent with kaitiakitanga and provides for the protection of the relationship of iwi with the historic, traditional, cultural and spiritual elements of Te Awa Kairangi/Hutt River and its supporting ecosystems.


Objective 7.3.1 Objective 7.3.2 Policy 7.4.2 Policy 7.4.3 Policy 7.4.4 Objective 12.3.2 Objective 13.3.2 Objective 15.3.1 Policy 15.4.1 Policy 15.4.3

The UHCC DP seeks to promote a high level of environmental quality and protect open space and visual amenity values and to avoid, remedy or mitigate adverse effects of activities in areas of open space. The UHCC DP also seeks to promote the development of a safer and more secure environment for the community. Following completion of construction, the natural and ecological qualities of the river will be maintained, and likely enhanced, through replacement planting, and new areas of restoration planting. Once completed the Project will result in enhanced access to the river corridor, and provide public access to an area of the river corridor that is not currently accessible to the public, this will enhance recreational values alongside the river margins The Project will result in a significant improvement in amenity values and open space which will increase use of the river corridor and contribute to a safer and more secure environment. The Project achieves this through the provision of improved cyclist and pedestrian access across the river and restoration and landscape planting which provides improved amenity for the community and habitat for wildlife.

Natural hazards Objective 9.3.3 Policy 9.4.1 Policy 9.4.2 Policy 9.4.6 Policy 9.4.7 Policy 9.4.8 Objective 14.3.1 Policy 14.4.1 Policy 14.4.2 Policy 14.4.3 Policy 14.4.4 Objective 16.3.3 Objective 16.3.5 Policy 16.4.18 Policy 16.4.19

Flooding Effects of the access embankments on flood flows and storage have been modelled with assessment concluding there will be a negligible increase in flood levels. The Project seeks to avoid or otherwise minimise increasing flood risk. The pipe bridge has been designed to accommodate a 2800 cumec flood. This means the pipe bridge will not be inundated or act as a barrier to flood flows in the 2800 cumec design event. In addition, the bridge piles, access embankments and abutments have all been located and designed to be as resilient as practicable against scour in the design flood event. Policy 14.4.3 requires avoidance of development within high hazard areas of identified Flood Hazard Extents and Erosion Hazard Areas. While the proposal cannot entirely avoid development in the high hazard areas, permanent structures have been designed and located to be as resilient as possible to scour and erosion as a result of flood events. Overall, the Project has sought to avoid or otherwise minimise adverse effects of flooding as a result of project works and is consistent with the provisions of the UHCC DP related to flood risk. Seismic Resilience The seismic risks associated with being within close proximity to the Wellington Fault cannot be avoided. Instead, the Project has been designed



Comment

and aligned such that, in the event of failure or damage in a significant seismic event, the bridge and pipeline can be quickly and easily repaired. The Project design has had regard to the most appropriate separation distances from the Fault and the design of the bridge and pipeline has been undertaken in accordance with the most up to date industry standards to meet acceptable levels of resilience and safety based on site specific hazard assessments. Earthworks in the floodplain Earthworks within the flood hazard zone, with the exception of the access embankments, the earthworks will be temporary, with the ground reinstated to its current condition and levels upon completion of works. All earthworks will be suitably engineered and undertaken in a manner which minimises effects on habitats of indigenous fauna. The use of erosion and sediment controls in accordance with the GWRC Erosion and Sediment Control Guidelines 2021 will be implemented to minimise erosion, control sediment run-off and to ensure areas of disturbance are stabilised and vegetation cover is restored as soon as practicable. This will be managed by way of ESCP, secured by conditions of consent. It is considered the Project avoids any adverse effects on the function of the floodplain.

Water quality Objective 13.3.1 Objective 13.3.2 Policy 13.4.1

The UHCC DP seeks to protect and enhance water quality and diversity of aquatic habitats, and to void, remedy or mitigate the adverse effects of land use activities on water the quality and the diversity of aquatic habitats. The potential effects on water quality arise from excavation in the floodplain and disturbance of the river bed during construction activities. These activities will be temporary and the Project will utilise best practice techniques, secured by an ESCP and conditions of consent, during construction to manage sediment. The Project’s sediment discharges will result in a negligible contribution to the existing sediment loading of Te Awa Kairangi, and effects will be appropriately managed. With the proposed measures in place to manage adverse effects on freshwater quality from discharges of sediment, any potential effects on freshwater and associated ecosystems will be minimised.

Biodiversity and ecology Objective 12.3.1 Policy 12.4.1

The UHCC DP requires the protection and enhancement of significant indigenous ecosystems and biodiversity, and seeks to protect and enhance significant natural areas of indigenous vegetation and fauna habitats from the adverse effects of activities that would reduce indigenous biological diversity and/or the life supporting capacity of ecosystems. The Project will be consistent with the relevant provisions of UHCC DP. A range of measures are proposed to minimise the potential effects of the Project on ecological values, any birds migrating or roosting in the Project area and trout habitat, these measures will be secured by the EMP and conditions of consent. The Ecology Assessment has determined that the effects of the Project on freshwater ecology values will be temporary and at worst, minor.

General amenity effects Objective 15.3.1 Policy 15.4.4

The UHCC DP seeks to manage noise levels such that they are acceptable to the community. In relation to the Project this applies to noise in the Open Space Area during construction activities. As outlined in section 9.2.3.1 compliance with applicable noise limits in the UHCC DP will be achieved during construction activities. Construction works at night will be avoided and night-time activities (delivery of oversized plant and construction materials) will be compliant with noise limits. Further measures to minimise construction noise will be outlined in the CEMP. The Project will be consistent with the noise objectives and policies of the UHCC DP.


11.2.7 Proposed Natural Resources Plan

The PNRP is the combined regional plan for the Wellington Region. Parts of the plan are currently under appeal. It is expected that appeals on provisions relevant to the Project will largely be resolved by the time of lodgement, but some relevant provisions are likely to be altered through consent orders during the intervening period. An assessment of relevant provisions, as per the Appeals Version at 9 August 2021, is set out in Table 33.

Table 33 Proposed Natural Resource Plan objectives and policies assessment


Comment

Integrated management

Objective O1 Objective O2 Objective O3 Objective O4 Policy P1 Policy P2 Policy P3

These objectives and policies of the PNRP relate to the holistic management of resources, recognising the intrinsic values of air, land and water to the social, economic and cultural wellbeing of the community. The Project has been developed in accordance with the principles of integrated management (Objective O2). The assessment of the Project has been undertaken on a whole of catchment basis (ki uta ki tai) with potential effects being considered and managed in an integrated manner as consistent with Objective O1 and Policy P1, while acknowledging the cross-boundary interactions of Te Awa Kairangi/Hutt River as directed in Policy P2. Objective O3 seeks to sustain the mauri of fresh and coastal waters and where it has been depleted, natural resources and processes are enhanced to replenish mauri. Objective O4, which relates to recognition of the intrinsic values of freshwater and safeguarding its life supporting capacity, is particularly relevant. The Project design includes restoration of the river corridor with native species to improve the opportunities and habitat available for biodiversity and restore and improve the mauri of the river over-time. A precautionary approach has been adopted for the bridge design in a manner consistent with Policy P3, with the bridge deck being located above the HRFMP requirements which already accounted for climate change considerations, with an additional buffer provided for further protection against flooding. The Project will appropriately protect the intrinsic values and safeguard the life supporting capacity of Te Awa Kairangi/Hutt River.

Regionally significant infrastructure

Objective O12 Objective O12A Objective O13 Policy P12 Policy P13 Policy P14

These objectives and policies of the PNRP seek to recognise the benefits of RSI and that it meets the needs of present and future generations, including having particular regard to the strategic integration of Regionally Significant Infrastructure and land use and providing for development of RSI (Policy P13). The PNRP also seeks to ensure that RSI is not compromised by incompatible activities. This includes avoiding, remedying and mitigating adverse effects on RSI as a result of new use and development. The Project is required to protect and improve the resilience of RSI and is therefore supported by the provisions of the PNRP. The Project has been developed in an integrated manner ensuring that the replacement water supply infrastructure associated with the Project is compatible and supports (and enhances) the surrounding land use as consistent with Policy P12. The Project achieves this by providing the opportunity to improve connectivity of existing and planned pedestrian and cycling networks. In respect of potential reverse sensitivity effects on existing RSI, the Project will involve works in the rail corridor and discrete areas of SH2, and the relocation or realignment of network utility services, some of which are RSI. The proposed pipe bridge has been located downstream of the rail bridge which is RSI and when completed will remove the need to dig up SH 2 to carry out repairs or maintenance on the pipeline in future. GWRC Flood Protection, Waka Kotahi and UHCC as RCA have been consulted. The applicant has also consulted with Vodafone and will continue to work with affected network utility providers to minimise disruption and allow for the continued safe and efficient operation of network utilities during construction and in the long term, consistent with Policy P14.



Comment


Objective O14 Objective O15 Policy P17 Policy P18 Policy P19 Policy P20 Policy P21 Policy P44

The PNRP requires that the relationships of Māori and their culture and traditions with their ancestral lands, water, sites, waahi tapu, and other taonga are recognised and provided for; kaitiakitanga is recognised; and Mana Whenua actively participate in planning and decision making (Objectives O14 and O15). As per Policy P18, Te Awa Kairangi/Hutt River is identified as Ngā Taonga Nui a Kiwa to Taranaki Whānui and Ngāti Toa. The applicant recognises the relevant statutory acknowledgements of both iwi consistent with Policy P21. Taranaki Whānui Taranaki Whānui have actively participated in the development of the Project, including through the MCA process and pre-application consultation. A Position Statement has been prepared by Taranaki Whānui in relation to the Project, describing the relationships to the whenua and awa, and providing recommendations for mitigating effects on cultural values. The Position Statement requires that consultation with Taranaki Whānui shall continue during the design process, development of management plans and through collaboration on conditions of consent providing opportunity to deepen human, spiritual and cultural connection with the river environment consistent with Policies P19 and P20. As consistent with Policy P17, adverse effects on mauri have been assessed and the Position Statement recognises and provides for the role of kaitiaki in sustaining mauri through the detailed design and construction of the Project. Ngāti Toa Since the initial response from Ngāti Toa received in October 2020, the applicant has made numerous attempts to obtain the feedback of Ngāti Toa with no formal response from Ngāti Toa received to date. As part of the partnership agreement between Ngāti Toa and the applicant the applicant will continue to consult with Ngāti Toa during the consenting, detailed design and construction phases of the Project. In addition, Ngāti Toa will be able to make a submission reflecting any concerns or opinions they have regarding the Project during the notification period of this consent application. The Project is consistent with the Māori relationships and cultural effects direction in the PNRP.


Objective O9 Objective O10 Objective O17 Policy P9 Policy P10 Policy P24 Policy P48

The PNRP seeks to maintain and enhance recreational values, maintain and enhance public access and to preserve and protect from inappropriate use and development the natural character of rivers and lakes. In relation to recreational values, the Project will enhance public access to the river corridor for pedestrians and cyclists (P9), and enhance the recreational opportunities available to the community within and adjacent to the river corridor and improve access to the river for swimming and fishing. This will therefore enhance recreational values of Te Awa Kairangi/Hutt River. The Assessment of Natural Character, Landscape and Visual Effects describes that during construction, there will be a temporary effect on natural character. Construction works will be staged and the maximum footprint and duration of disturbance at any one time will be limited to minimise these effects to the extent practicable. This is in keeping with Policy P9. Once construction has been completed, there will be opportunities to restore riverside planting and to reinforce existing planted areas to preserve natural character. Overall, levels of natural character are considered to be maintained to their original level (moderate-low) with opportunities to further enhance natural character through planting and associated habitat creation along river margins. The Project is not considered to be an inappropriate use or development (Objective O17). During construction of the Project there may be some inconsistencies with the policy direction in the PNRP in the form of adverse effects on natural character values as a result of construction activities within and adjacent to the river; however, following completion of the construction works, the Project will avoid, remedy and mitigate adverse effects in a manner which maintains natural character, and landscape, visual amenity and recreation values as



Comment

consistent with Policies P24 and P48. As outlined in section 9.5 of this AEE, the Project also results in opportunities to enhance the natural character and landscape and recreation amenity values post-construction.

Natural Hazards Objective O20 Objective O21 Policy P27 Policy P28 Policy P29 Policy P104

The PNRP seeks to manage the effects of natural hazards and climate change on people, the community and infrastructure to an acceptable level and to avoid inappropriate use and development in high hazard risk areas. Objective O21 and Policy P27 of the PNRP seek to avoid use and development within high hazard risk areas (which includes the bed of rivers) unless five cumulative criteria are met:

- There is a functional need for the activity to be located in that area. - The residual risk after hazard mitigation measures is low. - The development does not cause or exacerbate hazards in other areas. - Adverse effects on natural processes are avoided, remedied or

mitigated. - Natural cycles of erosion natural cycles of erosion and accretion and

the potential for natural features to fluctuate in position over time due to climate change over at least the next 100 years are taken into account. (Policy P27).

The Project has been designed and adverse effects modelled in a manner consistent with the advice provided by GWRC Flood Protection based on the time period provided for in the HRFMP (90 years or out to 2070). As outlined in the Hydraulic Design Report, due to the uncertainty in estimating flood effects beyond 2090 GWRC Flood Protection advised no further modelling was required. The works proposed in the bed of Te Awa Kairangi/Hutt River involve minor recontouring of in-situ river material to provide for safe and efficient construction. Assessment has identified the Project will not cause or exacerbate hazards in other areas (Objective O20). Adverse effects on natural processes have been minimised to the extent practicable through the bridge design. In relation to Policy P28, the proposed pipe bridge forms part of a broader lifelines resilience strategy and is considered necessary to protect infrastructure from unacceptable hazard risk. As such, the Project is supported by the PNRP. In accordance with Policy P29, the effects of climate change on biodiversity, natural hazards and aquatic ecosystem health and mahinga kai have been taken into account throughout the design process and it is noted that the requirements of the HRFMP and the Bridge Manual which prescribe the design standards that the Project must achieve also include consideration of the effects of climate change. As noted above, the Project has been designed and effects modelled in a manner taking into account the flood related impacts of climate change specified in the HRFMP and directed by GWRC Flood Protection. There will be no more than minor adverse effects on existing catchment based flood and erosion control activities (Policy P104).

Contaminated land Objective O43 Objective O51 Policy P89 Policy P95

The PNRP seeks to protect the environment from discharges from contaminated land and to avoid the creation of new contaminated sites. The DSI concludes that there will be no risk to human health or the environment as a result of discharges from contaminated land. Effects from disturbance will be appropriately managed through a CLMP which will include best practice control measures and site-specific management techniques where necessary during the construction phase (Objective O43). The measures in the CLMP will avoid and otherwise minimise discharges from contaminated land and will avoid creation of new contaminated areas. The Project is therefore consistent with the PNRP direction for discharges from contaminated land in Objective O51 and Policies P89 and P95.

Water quality Objective O23 Objective O24

The PNRP seeks to ensure that the quality of groundwater, surface water and coastal marine area is maintained or improved (Objective O23) and water



Comment

Objective O25 Objective O46 Objective O47 Policy P62 Policy P63 Policy P67 Policy P70 Policy P71 Policy P72 Policy P98 Policy P101

quality in rivers is maintained or improved such that it is suitable for contact recreation and Māori customary use (Objective O24 and Policy P63). Water quality, flows, and aquatic habitat will be maintained during construction works and will therefore maintain ecosystem health and mahinga kāi (Objective O25). The direction of the PNRP seeks to promote discharges to land over discharges directly to water, and to minimise sediment runoff entering water. In relation to all discharges to land and water Policy P67 of the PNRP seeks to minimise the effects of all discharges by following a hierarchy which in the first instance avoids the production of contaminants and otherwise minimising the volume of the contaminants in any discharge using land-based treatment systems. Specifically related to earthworks, Objective O47 of the PNRP seeks to minimise the amount of sediment laden runoff entering water. To achieve this objective, Policy P98 requires the use of good management practice to minimise erosion, control sediment runoff and to ensure areas of disturbance are stabilised and vegetation cover is restored. The Project will ensure that riparian margins are maintained through planting with appropriate species and implementation of pest plant and animal control until planting has established as required by the Planting Establishment section of the EMP (Policy P101). As discussed in the Ecological Assessment, the Project proposes the implementation of best practice erosion and sediment control which includes treatment systems, and management of in-river works to be outlined in an ESCP. As a result, the Project’s sediment discharges will result in a negligible contribution to the existing sediment loading of Te Awa Kairangi/Hutt River, and effects of point source discharges from scour outlets and ESC devices will be appropriately managed such that they are no more than minor (Policy P70 and P71). This is consistent with limits on the zone of reasonable mixing as directed by Policy P72. Therefore, the Project is consistent with the PNRP’s direction to maintain or improve water quality.

Biodiversity and ecology

Objective O27 Objective O29 Objective O30 Objective O31 Objective O35 Policy P31 Policy P32 Policy P34 Policy P38 Policy P40 Policy P41 Policy P41A Policy P42

The PNRP seeks to protect and restore ecosystems and habitats with significant indigenous biodiversity values, through the careful management of activities and effects. Te Awa Kairangi/Hutt River is a scheduled site for indigenous biodiversity values (F1) so falls for consideration under Policy P40 and the mitigation hierarchy under Policy P41. The unnamed tributary is not identified as significant so falls under the hierarchy in Policy P32. With the implementation of avoidance and mitigation measures outlined in the EMP and other specific measures, secured by conditions of consent, the Project will be consistent with the direction in the PNRP for the following reasons:

- Natural flow characteristics will be maintained (P31) - Water quality will be maintained (refer assessment above) - Effects on freshwater fauna and terrestrial fauna will be avoided and

otherwise minimised through fauna relocations prior to works and careful staging and on-site management of construction works. All permanent structures will support fish passage (Objectives O29 and O31 and Policies P31, P34, P41A)

- In-river activities will be restricted at times or carefully managed to minimise effects on critical life cycle periods of avifauna and aquatic ecology

- Riparian habitat will be restored and enhanced (Objective O28 and Policy P31)

- The Project will avoid the introduction of pest plants and animals and contribute to the management of existing pest plants and animals (P31)

- The Project will have no more than minor effects on trout and will maintain trout habitat (Objective O30)



Comment

- In relation to the unnamed tributary that is not identified in the PNRP as ‘significant’ and therefore falls for consideration under Policy P32, significant adverse effects on ecological values have been avoided

- In relation to Policy P41, adverse effects on the significant indigenous biodiversity values of Te Awa Kairangi/Hutt River will be avoided or otherwise minimised such that they are no more than minor

- Consideration has been given to maintaining ecological connections and the cumulative effects of incremental loss of ecosystems and habitats with indigenous biodiversity values (Policy P42)

In summary, the Project is consistent with the policy direction in the PNRP in relation to biodiversity and ecological values.

Instream works / Activities within the bed of rivers

Policy P106 Policy P106 seeks to manage the introduction and removal of plants in the beds of rivers. The Project is consistent with this policy as the proposed removal of existing plants and introduction of new planting will be native with limited exotic species included for flood protection purposes.

Take, use and diversion of water

Policy P110 Policy P122 Policy P123 Policy P125 Policy P126 Policy P129 Policy P130 Policy P131

Surface water The PNRP provides for the take, use, damming and diversion of surface water as long as flows are sufficient to maintain aquatic ecosystem health and sediment transport, and natural and recreation amenity values of the water bodies. The Project will involve temporary damming and diversion of water to enable installation of the pipeline beneath the unnamed tributary. Any damming or diversion of water in Te Awa Kairangi/Hutt River during construction will be contained within the river banks, maintaining flows within the river system. As such any temporary diversions will have no more than minor effects on aquatic ecosystem health or natural or recreation amenity values consistent with Policies P110, P122 and P129. Groundwater The PNRP seeks to protect existing takes from being compromised by new bores, sets requirements around construction of new bores, requires protection of groundwater quality and seeks to manage the effects of dewatering activities. Effects of the Project on groundwater quantity and quality have been assessed in the Hydrogeology Assessment (Appendix E). Project activities with potential effects on the groundwater system include:

- Installation of geotechnical investigation bores - Dewatering of excavations during construction activities to provide a

dry working environment - Construction of bridge foundations and piles which extend into

underlying groundwater systems Having regard to Policies P125 and P126, a final DSMP will be developed and implemented to protect groundwater quantity and quality and to avoid any potential settlement effects during ground disturbance and dewatering activities. All investigation bores will be constructed in accordance with best practice and will be decommissioned when no longer in use in accordance with relevant standards (Policies P130 and P131).

General amenity effects

Objective O41 Policy P55

The PNRP seeks to manage discharge of contaminants to air to maintain air quality at appropriate levels to protect amenity values, human health and the quality of the environment. The effect of the Project on air quality is related to discharges of dust to air as a result of earthworks and construction activities. These discharges will be managed through best practice site management and specific mitigation measures during construction which will be secured in accordance with the CEMP. With mitigation measures in place, potential offensive and objectionable



Comment

effects on human health, property and the environment are not anticipated beyond the boundary of the construction areas. The discharge of dust associated with construction of the Project will be appropriately managed consistent with the PNRP provisions in Objective O41 and Policy P55. The dust emissions associated with construction of the Project are therefore consistent with the relevant objectives and policies of the PRNP.

11.3 Other matters

Section 104(1)(c) requires decision makers to have regard to other matters relevant in consideration of the application. A discussion of other matters considered relevant to the resource consent applications is provided below.

The Project has been shaped in accordance with key legislation and policy that provides strategic direction and guidance on the respective statutory roles and responsibilities of the regulatory authorities. In addition to the RMA matters, the key legislation and policies that have guided the development of the Project relate to:

– Flood protection strategy, including the HRFMP and associated community based flood management strategies;

– Spatial planning and growth strategies for Hutt City and Upper Hutt which set out principles, for the coordinated development and design of open space and the river corridor and its immediate environs; and

– Urban design guidance including the New Zealand Urban Design Protocol and National Crime Prevention through Environmental Design Guidelines (CPTED).

11.3.1 National context

11.3.1.1 National Crime Prevention Through Environmental Design Guidelines (2005)

The National Crime Prevention Through Environmental Design (CPTED) guidelines outline how urban planning, design and place management strategies can reduce the likelihood of crime and deliver numerous social and economic benefits in the long-term. Places that are safe and feel safe are vibrant – they attract people, activity and positive social interaction. Popular places are also better for business, with high pedestrian counts reflected in higher turnover, employment, profit and investment.

The CPTED guidelines introduce seven qualities of safer places, these are qualities that will improve the urban environment while reducing crime and the fear of crime.

Of particular relevance to the Project, CPTED guidelines encourage local authorities to adopt, develop and implement a framework to raise public awareness of crime prevention and safety and its link to the built environment. This seeks to promote the value of crime prevention as a key component of good design which will achieve more attractive and vibrant public places; these outcomes, in turn, enhance public safety and reduce opportunities for criminal offending.

The CTPED guidelines also encourage design to take into consideration long-term maintenance requirements, while ensuring quality design and encouraging use. The Project responds to maintenance and management through a design that seeks to minimise ongoing operational costs and the frequency of required maintenance of structures and design features.

The design has been informed by CPTED principles. These principles will continue to be incorporated into the detailed design and the UDLP.


11.3.2 Regional context

11.3.2.1 Hutt River Floodplain Management Plan (2001)

The HRFMP is a 40-year blueprint for managing and implementing programmes that will gradually reduce the effects of flooding from Te Awa Kairangi/Hutt River. The Plan is a foundation for implementing structural and non-structural flood protection measures, and includes an environmental strategy for enhancing the river environment.

The Plan was prepared by GWRC over a 10-year period with significant input from UHCC, HCC and Mana Whenua through the Hutt River Floodplain Management Sub-Committee, as well as community groups and organisations in the Hutt Valley. It reflects how the community believes the flood risk should be managed. The Sub-Committee (now renamed the Hutt Valley Floodplain Sub-Committee) is a joint sub-committee and includes councillors from GWRC, HCC and UHCC. It meets quarterly to oversee the implementation of the HRFMP.

The HRFMP outlines a holistic approach to flood protection, combining physical protection (such as stopbanks and river realignment) with non-structural measures (such as appropriate land zoning and preparing communities for flooding). It also looks at environmental opportunities and ways to enhance the river environment.

The HRFMP’s ultimate goal is to improve the wider Hutt Valley community’s resilience to flooding, allowing the community to maintain or enhance its present level of economic vitality and quality of life.

The HRFMP establishes a risk based design standard for flood protection within the Te Awa Kairangi/Hutt River floodplain. This design standard informs the level of protection proposed in the Project, including the height of the bridge above the river, the engineering standards for the base and construction of the bridge. The design standard is risk-based, which means that the level of physical works for a local area is determined by assessing the social, economic and environmental benefits and the costs of providing flood protection. The design standards are applied based on the impact of the flood event – a higher standard applies to areas such as Lower Hutt because of the potential social, economic and community loss as a result of a significant flood event.

Policy 3 from the HRFMP, the risk based 2,800 cumec design standard requires: new and replaced bridges and associated waterways to pass a 2,800 cumec flow”

This design standard is predicted to be equivalent to a 1 in 440 year event including an allowance for predicted climate change to 2090.

Section 4.5 of the HRFMP contains policies for managing utilities and services in the Te Awa Kairangi/Hutt River corridor. Policy 27 relates to services crossing the river corridor, and states that “services will only cross the river at approved or designated service crossings.” Policy 28 covers agreements for managing services in the river corridor.

The Project design has been informed by the HRFMP, in particular the bridge has specifically been designed to accommodate and be resilient to a 2,800 cumec flood. An MoU between WWL and GWRC is being prepared which sets out the asset management responsibilities for the pipe bridge and pipeline.

11.3.2.2 Te Awa Kairangi/Hutt River Environment Strategy and Action Plan (2018) (ESAP)

The Te Awa Kairangi/Hutt River Environmental Strategy Action Plan (ESAP) replaces the Hutt River Environmental Strategy (2001). The focus of the ESAP is on the enhancement and management of the river environment and the way it encompasses natural, social and cultural aspects or uses of the river corridor, in the widest sense, while providing flood protection.


The ESAP has been prepared by GWRC, in collaboration with UHCC, HCC and Mana Whenua. It identifies opportunities to enhance Te Awa Kairangi/Hutt River’s environment as part of HRFMP implementation, to help achieve many of the HRFMP’s environmental and community outcomes. The focus of the HRES is:

“on the enhancement and management of the river environment and the way it encompasses natural, social and cultural aspects or uses of the river corridor, in the widest sense, while providing flood protection”.67

The ESAP includes three goals, related to the natural environment, community and recreation, and a number of objectives to guide the reach-specific concept plans. The strategy provides concept plans that identify ideas or opportunities for enhancing the river environment in line with the linear park vision for Te Awa Kairangi/Hutt River. These opportunities are either linked to capital works within each reach along Te Awa Kairangi/Hutt River, or exist as separate enhancement opportunities.

The Project will seek to support this strategy by incorporating a cycle and walkway into the bridge construction itself. This will help to connect the left and right banks of the river at Silverstream. Other amenity features are being proposed such as restoration of native vegetation within the river corridor to replace exotic species that are being removed and maintaining and improving lizard habitat on the West side of the river.

Within the ESAP, the Site is identified within the Pomare Rail Bridge to Silverstream Bridge sector. Opportunities identified for this area include enhancing the ecological corridor across the river between the indigenous forest located on both sides of the river. Additional planting of indigenous vegetation to further enclose the river corridor, particularly the open grassed area, will create a contrasting experience for Hutt River Trail users, giving the reach a more ‘wild’ and ‘bush’ aesthetic.

An action that was identified is to maintain and enhance the Silverstream Bridges area as a recreation destination. The Project will achieve that by adding a new bridge to this area and providing pedestrian/cycle access that will improve the connection to existing and planned active transport networks, further enhancing this area of the river corridor as a recreation destination.

11.3.2.3 Whaitua te Whanganui-a-Tara

Whaitua te Whanganui-a-Tara is a catchment-based initiative which brings together an independent committee of local people from the Hutt Valley and Wellington working in partnership with Mana Whenua to develop a programme to improve the quality of the Wellington / Whanganui-a-tara streams, river and harbour.

The programme is currently under development and expected to be delivered for community feedback by August 2021. The programme will include recommendations for specific work programmes, and regulatory plan provisions.

These measures will seek to provide for the integrated management of land and water resources to improve water quality. The recommendations and measures are anticipated to inform future regulatory plan changes and establish a programme of work to achieve the community’s objectives for water quality and quantity in the whaitua (catchment).

11.3.2.4 Wellington Regional Growth Framework 2021

The Wellington Regional Growth Framework is a regional level spatial plan that provides a 30-year vision for how the region will grow and respond to growth and urban development challenges. The purpose of the framework is to help to guide and co-ordinate regional scale urban planning and align investment in infrastructure and services.

67 Page 5, Hutt River Environment Strategy and Action Plan 2018


It is a region-wide collaborative project between GWRC, the city and district councils within the Wellington Region, Mana Whenua, Waka Kotahi and the Ministry of Housing and Urban Development. It takes into consideration these partners’ existing work to plan for and accommodate Wellington’s growth. The framework has 6 objectives:

– Increase housing supply and improve housing affordability and choice

– Enable growth that protects and enhances the quality of the natural environment and accounts for a transition to a low/no carbon future

– Improve multi-modal access to and between housing, employment, education and services

– Encourage sustainable, resilient and affordable settlement patterns/urban form that make efficient use of existing infrastructure and resources

– Build climate change resilience and avoid increasing the impacts and risks from natural hazards, and

– Create employment opportunities.

Submissions on the Wellington Regional Growth Framework closed in May 2021. The Project will help to enable the objectives of the framework through the continued supply of water, improving water supply resilience. It will also enable safe multi-modal transport in the Silverstream reach of the Hutt River. The design of the bridge and pipeline has also incorporated additional resilience related to predicted changes in natural disasters due to climate change.

11.3.2.5 GWRC Long Term Plan – water supply

The long term plans sets out what GWRC will do over the 10 years between 2021-2031 in the Wellington Region. The relevant section of the long-term plan related to the Project is the Water Supply section. This section developed a number of priorities for water management which included:

– Thriving environment - providing clean and sustainable drinking water and reducing water demand and providing bulk supply that is respectful to the environment.

– Resilient future - bulk water supply that is robust, to ensure sufficient drinking water is available for the immediate future and for generations to come.

– Connected communities - The region has sufficient water supply that is of high quality and safe

Furthermore, the Project was expressly identified within the Long-Term Plan for replacement within the 2021-2024 period. It has been identified as a water supply Key programme.

The Project helps to implement GWRC’s long-term priorities for water supply, in particular by increasing the resilience of vital municipal water supply infrastructure for Wellington and Porirua as well as providing resilience in the event of natural disasters.

11.3.3 Local context

11.3.3.1 Lower Hutt Growth Story (LHGS) (2018)

The Lower Hutt Growth Strategy is a summary of the urban growth, land use, transport, and resilience goals for Lower Hutt. It particularly identified, as a desired outcome, improving resilience from major events and more focus on active modes and multi-modal connections. With respect to multi-modal transport the plan identifies continuing to improve the Hutt River Trail.

The Project will help to implement these strategies by improving the resilience of existing transport infrastructure as well as providing a resilient and separate active mode of transport between Hutt City and Upper


Hutt. Provision of cyclist and pedestrian connections at Silverstream as part of the bridge design will address a missing link in the regions’ pedestrian and cycleway network and improve connectivity to the Hutt River Trail.

11.3.3.2 Upper Hutt Land Use Strategy (2016 – 2043)

The Upper Hutt Land Use Strategy has been prepared to align with the Long Term Plan with respect to not only land-use but also the integration of transport, infrastructure and the environment with land-use needs from the community and economy of Upper Hutt City.

The strategy encourages the expansion and protection of environmental resources as well as the delivery of quality infrastructure that is resilient, efficient and also encouraging further development of sustainable transport.

The Project is designed to be resilient in a 2800 cumec flood, as well as in significant seismic events and thus has been designed to be resilient to future disasters. It also enhances the connectivity of the city with the inclusion of a shared path over the bridge which encourages further development of Upper Hutt’s sustainable transport network.

11.3.3.3 Upper Hutt City Council Infrastructure Strategy (2018-2048)

The Upper Hutt City Council Infrastructure Strategy is a component of its long-term plan and outlines the strategy for the following infrastructure assets:

– Three waters: wastewater, stormwater, water supply

– Land Transport

– Parks and reserves, and

– Council property

Relevant focus areas in this plan, for the Project are:

– Water supply: Improving resilience in the event of a natural disaster (pipes, storage and supply).

– Land transport: providing cycling and walking facilities that meets the agreed levels of service for all ages

– Parks and reserves: providing and extending of cycling and walking facilities.

The Project includes a bridge that is resilient to foreseen natural hazards, in particular significant seismic events as well as a 2800 cumec flood. The inclusion of the shared pathway in particular will meet the focus areas for land transport and will utilise the existing reserves and create additional separate connections for cyclists and pedestrians. This will help to integrate Upper Hutt’s cycle and walkways with Hutt City’s as well as improving the amenity of the area for residents.

11.3.3.4 Upper Hutt City Long Term Plan (2021-2031)

The Upper Hutt City Long Term Plan identifies the long term focus to council activities and decision making. The Long Term Plan identifies, as a focus area in the land transport activity group, providing cycling and walking facilities that meet agreed levels of service for all ages. The Project, as a component of the wider Te Awa Kairangi cycle and walkway corridor, will help to provide additional transport for cycling and walking throughout the Hutt Valley.

11.3.3.5 Hutt City Council Infrastructure Strategy (2018-2048)

Hutt City’s infrastructure strategy is to identify the significant infrastructure challenges and opportunities for Lower Hutt over the next 30 years.

The underlying principles of the infrastructure strategy are:


– Protect people, property and the environment

– Ensure infrastructure is resilient in the long-term and adaptable to changing circumstances

– Maintain an overarching community understanding and awareness of infrastructure services and issues facing them

– Ensure robust information underpins long-term infrastructure decisions

– Maintain strong collaboration with stakeholders and partners

– Ensure infrastructure complies with all appropriate regulations and standards

These lead to a further set of goals with respect to infrastructure, these are:

– To ensure infrastructure supports the growth of our safe, healthy, liveable and vibrant city.

– To increase the resilience, sustainability and long term adaptability of the infrastructure.

– To improve the design, development and management of infrastructure to serve the community needs, desires and aspirations

– To upgrade the infrastructure to reinforce the growth of our strong, diverse and innovative economy

– To strengthen the reliability, efficiency and effectiveness of the infrastructure networks

The Project is consistent with the principles and goals of the infrastructure plan. The construction will protect people and the environment and will replace opportunistic exotic species with native plantings to improve the natural character and biodiversity values within the river corridor. The bridge and pipeline have been designed with all foreseeable increases in severity of natural events due to climate change taken into account. The bridge structure, and pipeline will not preclude other infrastructure from being developed in the area, such as a planned replacement for the Silverstream road bridge and will support the construction of an additional (smaller) pipeline in future. The inclusion of pedestrian and access in the bridge design has been incorporated in response to a community desire for additional cycling and walking infrastructure and will help to ensure that the community’s vision of a Hutt Valley cycleway are brought a step closer to being realised. The upgrade to the bulk water supply, through construction of the new bridge and pipeline, will ensure that bulk water supply is reliable and efficient for the foreseeable future.

11.3.3.6 Hutt City Long Term Plan (2021-2031)

The Hutt City Long Term Plan identifies the initiatives and services that are planned to be funded within the next 10 years. This identifies the Project and desires of community and ultimately provides certainty for funding particular projects and identifies the strategically important areas of investment.

The Hutt City Long Term Plan identifies several objectives for active transport modes that the current project will contribute to. In particular Hutt City Council are focused on improving community connectedness and travel options that people can use safely and easily. The cycleway/walkway on the pipe bridge will contribute to a safe and accessible active transport mode connecting Lower Hutt and provide additional transport modes along Te Awa Kairangi.

11.4 Section 105 assessment

Some of the resource consent applications are for discharge permits for contaminants into water and onto land. Therefore section 105 RMA is relevant. Section 105 RMA outlines additional matters that consent authorities must have regard to for discharge permits in addition to the matters in section 104(1) RMA, namely:

– The nature of the discharge and the sensitivity of the receiving environment to adverse effects; and

– The applicant’s reasons for the proposed choice; and

– Any possible alternative methods of discharge, including discharge into any other receiving environment.


11.4.1 The nature of the discharge and the sensitivity of the receiving environment

Discharge permits are being sought in respect of runoff from earthworks and discharges of contaminants to land where it may enter water, and discharges directly to water, during construction activities. Detailed consideration has been given to methods for addressing any potential adverse effects of these discharges, and appropriate methods will be adopted (including through design and construction methods) to ensure effects are appropriately managed.

The nature of the proposed discharges and sensitivity of the receiving environment in relation to the discharges during construction and operation have been outlined in section 9.3.3 of this AEE.

The sensitivity of the receiving environments can be summarised as follows:

– Te Awa Kairangi/Hutt River is identified as a river with significant indigenous biodiversity values in the PNRP.

– The Ecology Assessment has identified Te Awa Kairangi/Hutt River as having high ecological value.

– The affected unnamed tributary is assessed as having negligible ecological value.

It is noted sedimentation is an existing issue within the above freshwater environments, particularly following rainfall events. In this regard, the receiving environment already carries high contaminant loads, and any additional discharges from Project works (in particular sediment and heavy metals) will be indiscernible.

11.4.2 Discharges of contaminants to land and water during construction

During construction of the Project, discharges will occur to Te Awa Kairangi/Hutt River and the unnamed tributary. Discharges will largely consist of sediment run off from earthworks and general construction activities and suspended sediment as a result of construction activities within the river bed. The resultant effect of construction activities being that discharges as a result of run-off, and works in the river, mean the river may contain higher levels of sediment than normal during the construction period. Because works are required in areas within and adjoining surface water, and that works to create a dry working environment (i.e. diversion of flow) will in some instances be more invasive than undertaking works in flowing water as fast as practicable, discharges to surface water are considered unavoidable. However, where works occur outside of surface water, mitigation measures such as ESC controls will be implemented to prevent construction related discharges entering surface water. Measures to minimise the adverse effects of discharges will be adopted to remedy or mitigate effects where there is no feasible alternative discharge location or method. These options are summarised below.

Industry best practice site management and the proposed construction methodology will minimise effects on people and the environment to the extent practicable, particularly given works are required within and adjacent to areas with significant indigenous biodiversity values.

Key measures to minimise the effects of discharges include:

– Construction activities are conducted in a staged and confined manner with limited footprints and durations

– Management plan procedures to avoid, minimise, treat, and monitor discharges

– Monitoring and reporting procedures in management plans

Specific measures for relevant areas of the Project area are summarised below:

11.4.2.1 Works within and adjacent to surface water

Key measures to minimise the effects of works within surface water include:

– Avoiding work in low flow and ecologically sensitive seasons and procedures to avoid adverse effects on sensitive biodiversity


– Restricting the duration of works within and adjoining flowing water to protect aquatic habitat from prolonged sediment exposure

11.4.2.2 Works outside of surface water bodies

Key measures to minimise the effects of works outside of surface water bodies include:

– Avoidance of works in heavy rainfall events

– Progressive stabilisation to reduce the extent of disturbed surfaces and subsequent volumes of sediment generation

– Short term stabilisation (rock armour, hard fills and metals, geofabric) when rainfall events are forecast

– Separating sources of clean water from active construction areas

– Use of sediment treatment devices to treat sediment laden water before discharging to any river (via land)

– Chemical treatment to maximise performance of devices where reasonably practicable

– Erosion and sediment control measures to reduce erosion and detain contaminated sediments on site

– Contaminant testing and chemical treatment of any dewatering and stormwater runoff prior to discharge

The Project also has the potential to result in discharges of other construction related contaminants to surface water (i.e. cementitious products and fuels and oils). These contaminants will be managed in accordance with industry best practice. Disposal of contaminated land and any water which is unsuitable for site treatment will be subject to off-site disposal (landfill) as an alternative to discharging into the natural environment.

The Ecology Assessment (Appendix F) concludes that the effects of discharges of sediment and other contaminants during the construction phase of the Project will be, at worst, minor.

11.5 Section 107 assessment

Section 107(1) RMA sets out restrictions on granting discharge permits if, after reasonable mixing, the contaminant or water discharged is likely to give rise to certain effects in the receiving waters (as listed in s107(1)(c)-(g) RMA).

The Project involves discharges to water during both the construction and operational phases, although discharges during the operational phase (scour water) are permitted. The discharges meet the tests in section 107 RMA, allowing the grant of discharge permits for the following reasons:

– The potential for effects associated with odours, conspicuous oils, floatable or suspended materials on receiving waters from construction and operational discharges (s107(1)(c) and (e) RMA) will be minor (see section 9.3.3 of this AEE).

– The Ecology Assessment concludes that there could be minor effects on the colour and visual clarity of Te Awa Kairangi/Hutt River as a result of suspended sediment. Any effects will be of localised extent and temporary duration, as they are limited to construction activities and the construction period. After reasonable mixing these discharges are not expected to be conspicuous (s107(1)(d)).

– Based on the assessment of effects in section 9.3.3 of this AEE, there will be no significant adverse effects from the discharge of sediment or other contaminants on aquatic life during construction and operation of the Project (s107(1)(g)).

11.6 Part 2 analysis

Section 104(1)(b) of the RMA sets out the matters that decision-makers are required to have regard to when considering an application for resource consent and any submissions received.


Any such consideration, however, is subject to Part 2 of the RMA which sets out the purpose and principles of the RMA. The purpose of the RMA as stated in section 5 is to promote the sustainable management of natural and physical resources. The Court of Appeal in RJ Davidson Family Trust v Marlborough District Council68 has confirmed that decision-makers in resource consenting matters must have regard to Part 2 where "it is appropriate to do so"69 however, where the relevant plan provisions have clearly given effect to Part 2 there may not be a need to do so as it "would not add anything to the evaluative exercise."70 Nonetheless, it is a requirement of clause 2(1)(f) of Schedule 4 to the RMA that an application for a resource consent includes an assessment of the activity against the matters set out in Part 2.

Part 2 of the RMA requires decision-makers to consider different matters in exercising their functions under the RMA (matters of national importance (section 6), other matters (section 7) and the principles of the Treaty of Waitangi (section 8)), and stipulates the manner in which these matters are to be considered ("recognise and provide for," "have particular regard to," and "take into account," respectively).

When the benefits of the Project are considered alongside measures to avoid, remedy and mitigate adverse effects, it is considered the Project promotes the sustainable management of natural and physical resources and is consistent with the purpose and principles of the RMA. The purpose of the RMA will be achieved by granting the resource consents sought, subject to the consent conditions set out in this AEE.

11.6.1 Section 5 - Purpose

The Project will enable people and communities to provide for their social, economic and cultural wellbeing and for their health and safety through:

– Improving the resilience of the regionally significant potable water supply infrastructure.

– Providing significant community social and transport benefits by providing opportunities to improve connection to existing pedestrian and cycling networks, improving access and safety of users of these active transport networks

– Increased health and safety through increased protection against natural hazards resulting from a more resilient potable water supply network at this location

In balancing these considerations with the matters in section 5(2) of the RMA, the following conclusions are derived from the assessment in the preceding sections of the AEE:

– The Project will help safeguard the life supporting capacity of natural resources, specifically:

• Water – construction activities will avoid the active channel to the extent practicable and discharges from construction activities will be treated and there will be overall long-term benefits on water quality arising from re-vegetation and planting within the riparian margins of Te Awa Kairangi/Hutt River; and

• Ecosystems – by avoiding, remedying and mitigating effects of construction activities on ecological values.

The Project includes a suite of measures appropriate to the scale and significance of the potential effects that may arise during the construction and operation of the Project to avoid, remedy or mitigate those adverse effects.

For these reasons, the Project will achieve the RMA’s purpose of sustainable management of natural and physical resources.

68 RJ Davidson Family Trust v Marlborough District Council [2018] NZCA 316, [2018] 3 NZLR 283. 69 RJ Davidson Family Trust v Marlborough District Council [2018] NZCA 316, [2018] 3 NZLR 283 at [47] and [75]. 70 RJ Davidson Family Trust v Marlborough District Council [2018] NZCA 316, [2018] 3 NZLR 283 at [75].


11.6.2 Section 6 – Matters of national importance

The Project addresses the section 6 matters of national importance that must be recognised and provided, as follows:

(a) The preservation of the natural character of the coastal environment (including the coastal marine area), wetlands, and lakes and rivers and their margins, and the protection of them from inappropriate subdivision, use and development

During construction works, there will be a noticeable, but temporary, effect on natural character, in the river corridor. These works will be staged to minimise the effects to the extent practicable. Once the works are complete and habitat restoration in the form of planting has established, the Project will maintain, or even enhance, the natural character of Te Awa Kairangi/Hutt River, compared to the existing moderate natural character values in this location.

Overall, the Project recognises and provides for the preservation of natural character of Te Awa Kairangi/Hutt River.

(c) the protection of areas of significant indigenous vegetation and significant habitats of indigenous fauna

Project works will avoid to the extent practicable areas of significant vegetation and significant habitats of indigenous fauna. Measures are proposed to address unavoidable effects, namely disturbance of the river during bridge construction and to provide for restoration of aquatic habitats as quickly as possible. Positive effects will arise through restoration planting proposed in the river corridor, i.e. through the planting of native forest species that would have been the predominant vegetation in the floodplain historically. Overall, the construction methodology and conditions of consent will protect significant habitats of indigenous fauna (Te Awa Kairangi/Hutt River) during construction with freshwater habitat and species expected to quickly recover post-construction.

Overall, it is expected that proposed mitigation measures will appropriately protect significant indigenous vegetation and significant habitats of indigenous fauna.

(d) the maintenance and enhancement of public access to and along the coastal marine area, lakes, and rivers

While access to the river in the Project Area may be temporarily restricted during construction, in the long term the Project enhances public access to and along Te Awa Kairangi/Hutt River through the provision of pedestrian / cycle access across the river and the opportunity for improved connections to existing pedestrian/cycle routes within and along the river corridor.

(e) the relationship of Māori and their culture and traditions with their ancestral lands, water, sites, waahi tapu, and other taonga

The relationship of Māori and their culture and traditions with their ancestral lands, water, sites, wāhi tapu, and other taonga was taken into account in the development of the Project, in particular through the consideration of alternatives process. Going forward, the Position Statement provided by Taranaki Whanui recognises that the detailed design process will provide ongoing opportunities for Mana Whenua to incorporate cultural values into the Project through interpretive signage, input into the development of management plans and the conditions of consent.

Since October 2020 the applicant has made numerous attempts to obtain the feedback of Ngāti Toa with no formal response from Ngāti Toa received to date. As part of the partnership agreement between Ngāti Toa and the applicant the applicant will continue to consult with Ngāti Toa during the consenting, detailed design and construction phases of the Project. In addition, Ngāti Toa will be able to make a submission reflecting any concerns or opinions they have regarding the Project during the notification period of this consent application.


(h) The management of significant risks from natural hazards

There are two significant natural hazards risks that this Project has considered: earthquakes (the need to have water supplied to the population in Porirua and Wellington City) and flooding (to protect the bridge and pipeline from flooding events). The design of the bridge takes into account the possibility of flooding events that could impact the bridge. It is also designed so as not to increase or exacerbate flooding upstream or downstream and as such the proposal contributes to the management of significant risks from natural hazards. Design and construction measures will be used to mitigate flooding and earthquake risks to the extent possible in accordance with relevant national and local level design standards, including the HRFMP and the Bridge Manual. Significant risks of natural hazards are therefore considered to be appropriately managed.

11.6.3 Section 7 – Other matters

The following matters in Section 7 of the RMA have been given particular regard to:

– Kaitiakitanga and the ethic of stewardship (s.7(a) and 7(aa)) have been recognised. Kaitiakitanga and stewardship will continue to be recognised through the detailed design and construction of the Project, as recognised by the Taranaki Whānui Position Statement and conditions of consent. As part of the partnership agreement between Ngāti Toa and the applicant the applicant will continue to consult with Ngāti Toa during the consenting, detailed design and construction phases of the Project. In addition, Ngāti Toa will be able to make a submission reflecting any concerns or opinions they have regarding the Project during the notification period of this consent application.

– The efficient use and development of natural and physical resources (s.7(b)), whereby the Project will increase the resilience of regional significant potable water supply while also providing opportunities for improvements of pedestrian / cycle networks and the ability to accommodate additional services upon the bridge deck in future.

– The maintenance and enhancement of amenity values (s.7(c)) has been recognised, through the provision of riparian and landscape planting that contributes to improve amenity values and habitat for wildlife. The Project’s effects on amenity values during construction, especially those related to water quality and noise will be managed through implementation of construction management plans, adopting best practice techniques and site management measures. The UDLP process, and supporting consent conditions will appropriately manage, and are expected to enhance in the longer term, visual and natural character amenity effects on users of the river corridor.

– The Project will avoid any material adverse effects on the intrinsic values of freshwater and terrestrial ecosystems (s.7(d), with adverse effects on freshwater and the terrestrial environment being limited in both spatial extent and duration (temporary) and appropriately managed in a manner which maintains, and enhances in the case of terrestrial ecosystems, the intrinsic values of ecosystems in the long term.

– The maintenance and enhancement of the environment (s.7(e)), protection of ecosystems and the quality of the environment (both natural and physical) were key considerations during the design development and alternatives assessment processes and development of the construction conditions which seek to avoid adverse effects to the greatest practicable extent. Where adverse effects cannot be avoided, mitigation has been proposed to ensure that the quality of the environment is maintained and where possible enhanced. The Project is expected to result in overall positive effects on the Te Awa Kairangi/Hutt River environment at Silverstream.

– Te Awa Kairangi/Hutt River provides habitat to trout, and this has been considered in the Project design. Any effects on trout are expected to be temporary and limited to disturbance during works outside the active river channel.


– The effects of climate change (s.7(i)) have been considered through the design of the bridge, with predicted changes in the frequency and intensity of flood events due to climate change informing the design standards for the Project.

11.6.4 Section 8 – Treaty of Waitangi

The applicant recognises their role in taking into account the principles of the Treaty of Waitangi through their partnership with local iwi. Principles of the Treaty of the Waitangi have been taken into account through engagement with the relevant iwi early in the development of the Project. In developing the Project, recognition has been given to both the relationship of Mana Whenua to their lands, culture and traditions in this area and the commitment to partnership between Mana Whenua and the applicant.

In particular, Taranaki Whānui have provided cultural input and advice to inform the consideration of alternatives process. The partnership and relationship between Taranaki Whānui and the applicant will be maintained in the subsequent phases of the Project as recognised through the Position Statement.

Since the initial response from Ngāti Toa received in October 2020, where Ngāti Toa indicated that the project was not high on their priority list and there was limited capacity to provide someone to advise on the project, the applicant has made further attempts to obtain the feedback of Ngāti Toa and to provide a forum for the Project team to discuss the Project with Ngāti Toa. At this time, no formal response from Ngāti Toa has been received since October 2020. Wellington Water Limited continues to make efforts to engage directly with Ngāti Toa about the Project and as part of WWL’s partnership agreement with Ngāti Toa will continue to do so throughout the processing of the application and during the detailed design and construction phases. As the resource consent application is to be publicly notified, Ngāti Toa will also be able to make a submission reflecting any concerns or opinions they have regarding the Project during the notification period of this consent application.


12 Summary The purpose of this report is to present the required information in support of resource consent applications for the construction, operation and maintenance of the new pipe bridge and replacement section of the Te Marua to Karori main pipeline (Kaitoke Main) at Silverstream. Consent is required from Hutt City Council, Upper Hutt City Council and Greater Wellington Regional Council respectively.

The Project provides much needed resilience to the bulk water supply network to promote the health and wellbeing of the community, while being sensitive to the receiving environment and the recreational amenity values of the river corridor.

The statutory assessment that has been undertaken has concluded that the Project is consistent with the relevant objectives and policies of the applicable national, regional and district level statutory provisions.

The Project will promote the sustainable management of natural and physical resources and is consistent with the purpose and principles of the RMA. While the Project will result in some temporary adverse effects during construction, particularly in relation to ecology, landscape and visual amenity, and recreation and amenity values, the Project will result in significant long-term positive effects, particularly in relation to resilience, and social and recreational amenity values through provision of pedestrian and cycling access across Te Awa Kairangi/Hutt River. In summary the Project provides the following benefits:

– Minimises the time taken to restore supply of water to customers in Porirua and parts of Wellington City after a significant flood or earthquake event.

– Provides increased security of water supply to customers in Porirua and parts of Wellington.

– Reduces emergency water supply costs.

– Reduces community and business disruption following earthquake and flooding events.

– Reduces the need for emergency repairs which could take considerable time to carry out after an earthquake or flooding event.

Avoids disruption to a major transport route (SH 2) to restore the water supply after an earthquake or flooding event.

The preferred option is the construction of a network arch bridge spanning the Hutt River in a location downstream of the existing Silverstream road and rail bridges and upstream of the existing wastewater weir. This option was selected via an MCA process.

Throughout the consideration of alternatives, and the subsequent design process, the approach has been to avoid and, where avoidance is not possible, remedy or mitigate actual or potential adverse effects associated both with the construction stage and the operation of the Project.

The assessment of the effects on the environment in Section 9 of this AEE has identified a range of positive and adverse actual and potential effects on the environment from construction and operation of the Project. Potential adverse effects have been avoided where possible, or otherwise minimised to the extent practicable. A range of potential adverse effects still require mitigation. A suite of measures are proposed as part of draft conditions of consent, including management plans, supported by appropriate monitoring and maintenance, to manage actual and potential effects. To this end design features and construction methodologies have been adopted and will be further developed during the detailed design stage.

The overall conclusion is that in relation to 'adverse effects on the environment' the Project has effectively avoided, remedied and mitigated adverse effects. As a result, it is the conclusion of this AEE that the purpose of the RMA will be achieved by granting the resource consents sought for the Project.


Due to the likely wider public interest in the new pipe bridge as a result of the changes to natural character and amenity values in the popular Te Awa Kairangi/Hutt River corridor, public notification of this application is requested.

Silverstream Pipeline Replacement Project

Appendix A

Detailed Design Report


Appendix B

Figures


Appendix C

Detailed Site Investigation


Appendix D

Assessment of Dewatering Effects


Appendix E

Hydraulic Assessment


Appendix F

Ecological Impact Assessment


Appendix G

Assessment of Natural Character, Landscape and Visual Effects


Appendix H

Archaeological Assessment


Appendix I

General layout and preliminary design plans


Appendix J Assessment of relevant rules in regional and district plans


Appendix K

Engagement Register


Appendix L Iwi engagement correspondence


Appendix M Proposed consent conditions


Appendix N

Relevant objectives and policies of national, regional and district planning documents