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Port Geographe Coastal Structures Environmental Monitoring and Management Plan

924_09_001/1_Rev2 September 2016

Port Geographe Coastal Structures

Environmental Monitoring and Management Plan

Prepared for

Department of Transport

Prepared by

BMT Oceanica Pty Ltd

September 2016

Report No. 924_09_001/1_Rev2

Client: Department of Transport

Quality Assurance

BMT Oceanica Pty Ltd has prepared this report in accordance with our Health Safety Environment Quality Management System, certified to OHSAS 18001, AS/NZS 4801, ISO 14001 and ISO 9001 Status This report is 'Draft' until approved for final release, as indicated below by inclusion of signatures from: (i) the author and (ii) a Director of BMT Oceanica Pty Ltd or their authorised delegate. A Draft report may be issued for review with intent to generate a 'Final' version, but must not be used for any other purpose.

Approved for final release:

Author Director (or delegate) Date: 07 September 2016 Date: 07 September 2016 Disclaimer This report has been prepared on behalf of and for the exclusive use of Department of Transport, and is subject to and issued in accordance with the agreed terms and scope between Department of Transport and BMT Oceanica Pty Ltd. BMT Oceanica Pty Ltd accepts no liability or responsibility for it in respect of any use of or reliance upon this report by any third party.

Copying this report without prior written consent of Department of Transport or BMT Oceanica Pty Ltd is not permitted.

© Copyright 2016 BMT Oceanica Pty Ltd

BMT Oceanica: Department of Transport: Port Geographe Coastal Structures Environmental Monitoring and Management Plan i

Contents

Terms and Acronyms ................................................................................................................ iv

1. Summary ............................................................................................................................ 1

2. Context, Scope and Rationale .......................................................................................... 4

2.1 Project description ................................................................................................ 4

2.1.1 Seagrass wrack management ...................................................................... 6

2.1.2 Sediment management................................................................................. 7

2.1.3 Harbour entrance channel management ....................................................... 8

2.1.4 Summary ...................................................................................................... 9

2.2 Key environmental factors .................................................................................... 9

2.2.1 Coastal processes .......................................................................................10

2.2.2 Marine environmental quality .......................................................................10

2.2.3 Benthic communities and habitat .................................................................10

2.2.4 Air quality ....................................................................................................11

2.3 Requirements of the conditions ......................................................................... 11

2.4 Rationale and approach of the EMMP ................................................................ 12

2.4.1 Baseline studies ..........................................................................................12

2.4.2 Key assumptions and uncertainties .............................................................17

2.4.3 Management approach ................................................................................18

2.4.4 Rationale for choice of management actions ...............................................19

3. Implementation of the EMMP.......................................................................................... 21

3.1 Seagrass wrack management ............................................................................. 21

3.1.1 Condition environmental objective ...............................................................21

3.1.2 Management actions ...................................................................................21

3.1.3 Management targets ....................................................................................23

3.1.4 Monitoring....................................................................................................23

3.1.5 Review and revision of management actions ...............................................25

3.1.6 Reporting .....................................................................................................25

3.2 Sediment movement ............................................................................................ 26




3.2.4 Monitoring....................................................................................................29


3.2.6 Reporting .....................................................................................................31

3.3 Harbour entrance channel ................................................................................... 32




3.3.4 Monitoring....................................................................................................35


3.3.6 Reporting .....................................................................................................37

4. Adaptive Management and Reviews .............................................................................. 39

5. Stakeholder Consultation ............................................................................................... 41

6. References ....................................................................................................................... 43

ii BMT Oceanica: Department of Transport: Port Geographe Coastal Structures Environmental Monitoring and Management Plan

List of Figures

Figure ‎2.1 The Port Geographe Coastal Management Area and reconfigured breakwaters (updated version from Figure 1 in Ministerial Statement 990)............ 5

Figure ‎2.2 The Port Geographe Coastal Management Area, permanently installed bypassing pipeline, offshore disposal area, and Ngari Capes Marine Park exclusion zone ...................................................................................................... 7

List of Tables

Table ‎1.1 Summary of the Port Geographe Development Coastal Structures project, and associated condition environmental objectives and environmental management targets ............................................................................................. 2

Table ‎2.1 Coordinates of Port Geographe offshore disposal area ......................................... 6

Table ‎2.2 Summary of proposed maintenance dredging, wrack management and sand bypassing/nourishment campaigns at Port Geographe ......................................... 9

Table ‎2.3 Conditions of Ministerial Statement 990 and where they are addressed in this Environmental Monitoring and Management Plan ..........................................11

Table ‎2.4 Environmental, metocean, and engineering studies completed for the Port Geographe coastal structures development .........................................................12

Table ‎2.5 Recommended hydrogen sulfide exposure limits for public protection ..................16

Table ‎3.1 Risk-based management actions that will be implemented to meet the condition environmental objective relating to seagrass wrack management .........22

Table ‎3.2 Management targets to measure the efficacy of management actions related to the seagrass wrack management condition environmental objective ................23

Table ‎3.3 Routine monitoring to measure the efficacy of management actions against the management targets for seagrass wrack management ..................................23

Table ‎3.4 During-works monitoring to measure the efficacy of management actions against the management targets for seagrass wrack management ......................24

Table ‎3.5 EMMP reporting table for condition environmental objective relating to seagrass wrack management ..............................................................................26

Table ‎3.6 Risk-based management actions that will be implemented to meet the condition environmental objective relating to sediment movement .......................28

Table ‎3.7 Management targets to measure the efficacy of management actions related to the sediment movement condition environmental objective ..............................29

Table ‎3.8 Routine monitoring to measure the efficacy of management actions against the management targets for sediment movement.................................................29

Table ‎3.9 During-works monitoring to measure the efficacy of management actions against the management targets for sediment movement ....................................30

Table ‎3.10 EMMP reporting table for condition environmental objective relating to sediment movement .............................................................................................32

Table ‎3.11 Risk-based management actions that will be implemented to meet the condition environmental objective relating to the harbour entrance channel .........34

Table ‎3.12 Management targets to measure the efficacy of management actions relative to the harbour entrance channel condition environmental objective .....................35

Table ‎3.13 Routine monitoring to measure the efficacy of management actions against the management targets for the harbour entrance channel ..................................35

Table ‎3.14 During-works monitoring to measure the efficacy of management actions against the management targets for the harbour entrance channel ......................36

Table ‎3.15 EMMP reporting table for condition environmental objective relating to the harbour entrance channel ....................................................................................37

BMT Oceanica: Department of Transport: Port Geographe Coastal Structures Environmental Monitoring and Management Plan iii

Table ‎5.1 Stakeholder consultation, comments and responses to the Port Geographe Environmental Monitoring and Management Plan ............................................... 41

List of Appendices

Appendix A Ministerial Statement 990: Port Geographe Development Coastal Structures

Appendix B Department of Transport Maintenance Dredging – Environmental Management Framework (March 2016)

Appendix C OEPA correspondence regarding suitability of the DoT's Environmental Management Framework (8 October 2014)

Appendix D Example plume sketch and Secchi depth templates

iv BMT Oceanica: Department of Transport: Port Geographe Coastal Structures Environmental Monitoring and Management Plan

Terms and Acronyms

80th percentile Value below which 80% of the observations are found CD Chart datum CEO Chief Executive Officer of the Office of the Environmental Protection

Authority CoB City of Busselton DoH Western Australian Department of Health DoT Western Australian Department of Transport EAG Environmental Assessment Guideline EMF Environmental Management Framework EMMP Environmental Monitoring and Management Plan EMP Environmental Management Plan EPA Environmental Protection Authority GPS Global positioning system H2S Hydrogen sulfide gas LAC Light attenuation coefficient; a measure of the attenuation of light

with depth through the water column OEPA Office of the Environmental Protection Authority PGCMA Port Geographe Coastal Management Area ppm Parts per million Rolling two-year period A period of 24 consecutive months measured backward from the

current date UWA The University of Western Australia

BMT Oceanica: Department of Transport: Port Geographe Coastal Structures Environmental Monitoring and Management Plan 1

1. Summary This Environmental Monitoring and Management Plan (EMMP) is submitted in accordance with Ministerial Statement No. 990 (Appendix A), Condition 7 for the Port Geographe Development Coastal Structures by the Department of Transport (DoT) on behalf of the Minister for Transport. The EMMP also addresses Conditions 4, 5 and 6 of Ministerial Statement No. 990 (Appendix A). The content and format of this EMMP is consistent with the Environmental Protection Authority's (EPA) Environmental Assessment Guideline for Preparation of management plans under Part IV of the Environmental Protection Act 1986 (EPA 2015). The environmental management targets to measure achievement of the condition environmental objectives for seagrass wrack management, sediment movement, and the harbour entrance channel, that must be met through implementation of this EMMP, are outlined in Table 1.1.

2 BMT Oceanica: Department of Transport: Port Geographe Coastal Structures Environmental Monitoring and Management Plan

Table 1.1 Summary of the Port Geographe Development Coastal Structures project, and associated condition environmental objectives and environmental management targets

Title of proposal Port Geographe Development Coastal Structures Proponent Minister for Transport Ministerial Statement number 990

Purpose of this EMMP The Port Geographe Environmental Monitoring and Management Plan is submitted to fulfil the requirements of Condition 7 and also addresses Conditions 4, 5 and 6 of Ministerial Statement 990

EPA’s environmental objectives for the key environmental factors

Coastal processes To maintain the morphology of the subtidal, intertidal and supratidal zones and the local geophysical processes that shape them. Marine environmental quality To maintain the quality of water, sediment and biota so that the environmental values, both ecological and social, are protected. Benthic communities and habitat To maintain the structure, function, diversity, distribution and viability of benthic communities and habitats at local and regional scales. Air quality To maintain air quality for the protection of the environment and human health and amenity.

Condition environmental objective (seagrass wrack management)

Minimise the impact on the environment and human health due to trapped seagrass wrack.

Management targets (seagrass wrack management)

1. Maintain natural beachfront wrack dynamics by ensuring less than 60 000 m3 of wrack is on the Western Beach by December each year.

2. 24 hour average H2S concentrations adjacent to the Western Beach do not exceed Department of Health guidelines of 0.1 ppm.

3. Weekly (rolling 7-day) median light attenuation coefficient (LAC) at impact sites do not exceed the 80th percentile of the reference sites for two consecutive weeks (if completing offshore disposal during maintenance works).

4. No change in position of seagrass meadow edge outside of the predicted zone of influence of the offshore disposal area beyond natural variability (if completing offshore disposal during maintenance works).

Condition environmental objective (sediment movement)

Minimise the impact on the environment and coastal processes due to interruption to sediment movement by the reconfigured coastal structures.

Management targets (sediment movement)

1. Maintain natural alongshore sediment movement by ensuring less than 30 000 m3 erosion within Wonnerup Beach (to the eastern extent of the Port Geographe Coastal Management Area) at the end of a rolling two-year period (when compared to the November 2014 survey).

2. Weekly (rolling 7-day) median light attenuation coefficient (LAC) values at impact sites do not exceed the 80th percentile of the reference sites for two consecutive weeks (if completing offshore disposal during maintenance works).

3. No change in position of seagrass meadow edge outside of the predicted zone of influence of the offshore disposal area beyond natural variability (if completing offshore disposal during maintenance works).


2. Context, Scope and Rationale

2.1 Project description The Port Geographe development is located ~3 km east of Busselton, Western Australia. Developed in the 1990s, the original project saw the construction of breakwaters and groynes extending into Geographe Bay, together with a series of residential canals and a private marina. In 1991, Ministerial Statement 391 was issued to Tallwood Nominees Pty Ltd (Tallwood Nominees) for the construction of Port Geographe. The development has been progressively developed since the early 1990s. However, before completion, Tallwood Nominees experienced financial difficulties and the development ceased in mid-2009. The original design of the breakwater impeded the natural eastward littoral drift of sediment and wrack at the shoreline, causing large amounts of material to accumulate on the beach to the west of the harbour entrance channel (hereafter referred to as the 'Western Beach'). Decomposition of the accumulated wrack reduced the public amenity of this beach and resulted in reduced air quality in the surrounding area. The interrupted eastward littoral drift also led to erosion at Wonnerup Beach to the east of the development, threatening public and private infrastructure backing onto the beach. Wrack and sediment deposition in the harbour entrance channel affected the flushing characteristics of the Port Geographe artificial waterways. In 2013, the DoT became a joint proponent for Ministerial Statement 391. The DoT was responsible for the coastal structures component of the development, and responsibility for the land development and canal structures component was with Tallwood Nominees, until the land was purchased by Aigle Royal Developments in April 2015. In 2013 and 2014, the DoT completed construction and capital dredging campaigns to re-align the breakwaters in order to facilitate natural eastward littoral drift, thereby reducing the social and environmental impacts caused by the previous design. The reconfigured Port Geographe coast has two breakwaters (eastern and western) forming the entrance channel, a revetment along the eastern shoreline to Wonnerup and a small lagoon formed at the junction of the eastern breakwater and revetment (Figure 2.1, Figure 2.2). In 2013, Ministerial Statement 391 was amended to clarify the conditions within the statement, confirm the modifications to the coastal structures, and allow greater flexibility around the dredging volumes required for the reconfiguration. In November 2014, the Office of the Environmental Protection Authority (OEPA) finalised the Ministerial Statement and split it into two separate Ministerial Statements: Statement 989, for the management of the canal developments by the land owner; and Statement 990, for the management of the shoreline by the DoT. The proponent for Statement 990 is the Minister for Transport and the DoT completes environmental management on the Minister’s behalf. To ensure the conditions of Statement 990 are met, the DoT intends to maintain the area within the Port Geographe Coastal Management Area (PGCMA; Figure 2.1, Figure 2.2) that extends east and west of the reconfigured entrance channel, via periodic seagrass wrack and sediment management and harbour entrance channel maintenance dredging campaigns (summarised in sections below). These campaigns are facilitated by the presence of a permanent bypassing pipeline which, when deemed necessary, allows material to be pumped from one side of the development to the other (Figure 2.2).


Figure 2.1 The Port Geographe Coastal Management Area and reconfigured

breakwaters (updated version from Figure 1 in Ministerial Statement 990)


2.1.1 Seagrass wrack management Storms and energetic sea conditions may result in trapped wrack on the Western Beach. Wrack management works may need to be completed to reduce trapped wrack on the beach when it has the potential to cause an environmental impact, primarily due to the production of hydrogen sulfide gas (H2S). The method used to remove trapped wrack from the Western Beach will be dependent on the volume of wrack accumulated. Operationally, DoT may implement wrack management activities when accumulated volumes are above 30 000 m3. Historically an average of ~60 000–80 000 m3 of seagrass wrack can accumulate each winter on the Western Beach (BMT JFA 2015a), requiring management. Should a relatively small volume of trapped wrack be present on the Western Beach (~60 000 m3), wrack may be pushed into the littoral zone above the low water mark using land-based earthmoving equipment. Larger volumes of trapped wrack (~80 000 m3) may be removed from the Western Beach using land-based pumping equipment and/or trucking. Material may be pumped through the permanent bypassing pipeline and deposited in front of the eastern revetment pipeline connection (Figure 2.2), after which the material will typically continue to move in an eastward direction through natural processes. Seagrass wrack management options ensure that the nutrients provided by wrack remain within Geographe Bay. Aerobic decay of dry wrack generates substantially smaller amounts of H2S than anaerobic decay (which occurs when wet wrack decays at the waterline). Nearshore disposal is preferred, however if none of the nearshore disposal options listed above are suitable, the option for offshore disposal may be investigated. The proposed offshore disposal area is within the PGCMA and is also within the disposal area used previously for the 2013–2014 capital dredging campaign (Table 2.1, Figure 2.2). General seagrass wrack management works are typically expected to occur between September and November. Contingency seagrass wrack management works may be required if management target/s are not achieved. In this circumstance the contingency works on the Western Beach would be expected to commence in December (Section 3.1.5).

Table 2.1 Coordinates of Port Geographe offshore disposal area

Offshore disposal area1 position (GDA94 UTM50)

Easting Northing

North-west corner 351070 6278509 North-east corner 351305 6278515 South-east corner 351308 6278375 South-west corner 351073 6278369

Note: 1. See Figure 2.2 for offshore disposal area location in Port Geographe Coastal Management Area


Figure 2.2 The Port Geographe Coastal Management Area, permanently installed

bypassing pipeline, offshore disposal area, and Ngari Capes Marine Park exclusion zone

2.1.2 Sediment management It is anticipated that the shorelines and sediment levels within the PGCMA will eventually equilibrate to the reconfigured coastal structures and following this, sand is expected to naturally bypass across the harbour entrance channel to the beaches east of Port Geographe. However, prior to this, it is likely that the eastern beaches will require additional nourishment. The primary location for nourishment will be the western end of Wonnerup Beach, to allow natural eastward littoral drift of material along the shoreline. The supply options for nourishment material include external sources from outside the PGCMA (such as local quarries or sand pits), the Western Beach or the harbour entrance channel (provided the wrack content is expected to be low). It is noted that the dredging of nearshore sandbars outside the harbour entrance channel but within the PGCMA has also been considered as a potential source of nourishment material. However, it was deemed that, due to the nature of the complex coastal system, this potential source of sand for beach nourishment source should not be utilised unless a longer record of monitoring demonstrates there is a requirement to further alter this coastal system. Trucking of material from external sources outside the PGCMA (such as local quarries or sand pits) is more likely if surveys indicate smaller volumes are required for beach nourishment (e.g. 10 000–30 000 m3). Should surveys indicate that larger volumes are required (~50 000 m3), then a sand supply obtained from internal sources inside the PGCMA should also be investigated to minimise costs and potential transport impacts to local residents. This includes the option to mechanically bypass sand build-up on the Western Beach as a potential sand source inside the PGCMA, from where material would either be pumped through a pipeline or trucked.


However, it is intended that mechanical bypassing of sand from the Western Beach will be avoided where possible to allow this beach to naturally equilibrate against the new coastal structure configuration with minimal interference. In the event of an over-saturation of sediment on the Western Beach such that mechanical bypassing is investigated, there must be due consideration of: the beach profiles required to achieve the optimal natural bypass performance of the

reconfigured structures; and the propensity of this surplus sand to move into the entrance channel and cause a navigation

hazard. Any sand sourced for nourishment will consist of predominantly fine to medium grain sand, and will be free from contamination and debris. Works are typically expected to occur between October and December when no further storms are expected and prior to Christmas holidays when beach use will be high.

2.1.3 Harbour entrance channel management Maintenance dredging campaigns will be completed primarily to maintain the cross sectional area of the harbour entrance channel to ensure safe navigation and adequate flushing and water circulation. Material may also be dredged from areas adjacent to the harbour entrance channel to prevent infill if necessary. In most cases, a cutter-suction dredge will be used, and the disposal site will be dependent on the wrack content of the dredged material. If the scope only requires the removal of small volumes or isolated high spots, alternative methods such as wrack trawling or seabed ploughing may be considered. If the dredged material is expected to be suitable for beach nourishment (Section 2.1.2), it will be pumped through the bypassing pipeline and deposited through the Wonnerup Beach pipeline connection (Figure 2.2). If the wrack content of the material is expected to be high, it will be deposited in front of the eastern revetment via the established pipeline connection (Figure 2.2), after which the sandy material is anticipated to separate out and move eastwards to Wonnerup Beach. Both of these options are considered to minimise the risk of erosion on Wonnerup Beach. Nearshore disposal is preferred however if none of the disposal options listed above are suitable, the option for offshore disposal may be investigated. The offshore disposal area is within the PGCMA (Figure 2.2) and the location has been chosen to avoid and minimise impacts to seagrass meadows. Each maintenance dredging campaign will remove ~15 000–60 000 m3 of fine to medium grain sand and wrack from the harbour entrance channel. When required, works are typically expected to occur between September and December, when no further storms are expected and prior to Christmas holidays when marina and beach use will be high.


2.1.4 Summary A summary of the proposed campaigns at Port Geographe is outlined in Table 2.2. All details of the maintenance campaigns are indicative and will require review prior to each campaign.

Table 2.2 Summary of proposed maintenance dredging, wrack management and sand bypassing/nourishment campaigns at Port Geographe

Location Method Disposal site Volume Duration (weeks) Timing

Seagrass wrack management

Western Beach

Moved into littoral zone using earthmoving equipment Land-based pumping equipment and/or trucking

Western Beach littoral zone Eastern revetment pipeline connection Eastern end of Wonnerup Beach Offshore disposal area

~30 000–50 000 m3

1–12 September–December

Sediment management

External sources outside the PGCMA (such as local sand pits/quarries)

Trucking

Wonnerup Beach ~10 000–50 000 m3

4–8 October–December

Internal sources inside the PGCMA (such as the Western Beach and the entrance channel)

Bypassing (land-based pumping equipment) and/or trucking

Dredging (cutter suction dredge)

Harbour entrance channel management

Entrance channel and adjacent areas

Cutter suction dredge

Wonnerup Beach pipeline connection Eastern revetment pipeline connection

~15 000–60 000 m3

4–12 September–December

2.2 Key environmental factors This EMMP considers four key environmental factors that relate to the environmental management of the Port Geographe coastal structures. These factors are (EPA 2013): coastal processes marine environmental quality benthic communities and habitat air quality. The following sections describe the EPA's objectives for the protection of these four key environmental factors and outline why they are relevant to the Port Geographe coastal structures and the ongoing maintenance of this development. The EMMP management approach outlines how the condition environmental objectives and associated management targets protect these four key environmental factors (Section 2.4.3).


2.2.1 Coastal processes EPA's objective for coastal processes: To maintain the morphology of the subtidal, intertidal and supratidal zones and the local geophysical processes that shape them. The original design of the Port Geographe coastal structures impeded the natural eastward littoral drift of sediment and wrack at the shoreline, causing large amounts of material to accumulate on the beach to the west of the harbour entrance channel (Western Beach). The interrupted eastward littoral drift led to erosion at Wonnerup Beach to the east of the development. The reconfiguration of the Port Geographe breakwaters intends to facilitate natural eastward littoral drift along the Geographe Bay coast and ensure that the mechanisms for the transport of sand and wrack from beaches west of the development to beaches east of the development are reinstated. This involves monitoring natural coastal processes to ensure the reconfigured breakwaters are effectively promoting natural eastward littoral drift. However maintenance activities may also be required (see Section 2.1) before the beaches of the PGCMA reach equilibrium with the new coastal structures.

2.2.2 Marine environmental quality EPA's objective for marine environmental quality: To maintain the quality of water, sediment and biota so that the environmental values, both ecological and social, are protected. The presence of the Port Geographe coastal structures may cause large accumulations of trapped wrack that, when decomposing, can impact air quality and amenity in the surrounding area. The eastward transport of sand and wrack along the alignment of the Port Geographe coastal structures may cause some material to settle in the harbour entrance channel. This material may accumulate, reduce the cross sectional area of the channel, and potentially reduce water exchange between Geographe Bay marine waters and the Port Geographe waterways. Management of the harbour entrance channel depths, which is required for safe navigation and also to ensure adequate flushing of the artificial waterways, may involve maintenance dredging activities. These maintenance dredging and disposal activities have the potential to cause environmental impacts relating to marine water, sediment and biota quality at the dredging and disposal sites. In addition to maintenance dredging, further management activities may be required to maintain coastal processes and manage water and sediment quality within the DoT’s PGCMA (Section 2.1). These activities may include the mechanical bypassing of sediment and wrack from the Western Beach and sand nourishment of Wonnerup Beach. Bypassing and nourishment activities have the potential to cause environmental impacts relating to water, sediment and biota quality in the vicinity of the works.

2.2.3 Benthic communities and habitat EPA's objective for benthic communities and habitat: To maintain the structure, function, diversity, distribution and viability of benthic communities and habitats at local and regional scales. Extensive seagrass meadows exist in Geographe Bay and offshore of the Port Geographe coastal structures (outside of the PGCMA). Maintenance activities such as mechanical wrack bypassing that involve offshore disposal of material have the potential to cause environmental impacts on seagrass meadows in the vicinity of the offshore disposal area. These impacts are mainly related to short-term turbidity and potential smothering of seagrass meadows.


2.2.4 Air quality EPA's objective for air quality: To maintain air quality for the protection of the environment and human health and amenity. Decomposition of large accumulations of wrack by anaerobic bacteria on the Western Beach reduces the public amenity of the beach and results in reduced air quality in the surrounding area due to the generation of H2S. During maintenance activities (such as mechanical wrack bypassing), large quantities of H2S can be released over a short period of time which can potentially result in adverse health effects (ChemCentre 2010).

2.3 Requirements of the conditions This EMMP is submitted in accordance with Ministerial Statement 990, Conditions 4 to 7 for the Port Geographe Coastal Structures Development. The requirements of these conditions are addressed in sections of the EMMP as outlined in Table 2.3. The approach to how management actions have been developed to meet these conditions such that they follow the mitigation hierarchy and are protective of the EPA's key environmental factors, is explained in Section 2.4.3 and Section 2.4.4.

Table 2.3 Conditions of Ministerial Statement 990 and where they are addressed in this Environmental Monitoring and Management Plan

Ministerial Statement 990 Condition Section in EMMP

4-1 Where determined to be project attributable, the proponent shall maintain beach profiles on beaches east and west of the development, within the project area shown in Schedule 1, Figure 1, to the requirements of the CEO.

Section 2.1.2 Section 3.2

5-1 The proponent shall, unless otherwise approved by the CEO, annually bypass, dredge or remove trapped seagrass wrack and or sediment accumulated west of or within the harbour entrance, to the requirements of the CEO.

Section 2.1, Section 3

5-2 The proponent shall transfer sufficient sand to Wonnerup Beach for coastal protection, to the requirements of the CEO.

Section 2.1.2 Section 3.2

6-1 The proponent is to maintain the harbour entrance channel as per Schedule 1, to ensure adequate flushing and water circulation of the artificial waterways within the Port Geographe development, to the requirements of the CEO.

Section 2.1.3, Section 3.3

7-1 The proponent shall ensure impacts to the environment are minimised through the implementation of Conditions 7-2 to 7-8. Entire document

7-2 Within three calendar months following the issue of the Ministerial Statement, unless otherwise approved by the CEO, the proponent shall prepare an Environmental Management and Monitoring Plan to the requirements of the CEO. The Plan shall: (1) when implemented, substantiate whether Condition 7-1 is being met. (2) detail measures to manage water and sediment quality impacts to Geographe Bay associated with coastal management activities including dredging and bypassing. (3) detail measures to manage trapped seagrass wrack accumulation on the beaches adjacent to the development, as shown in Schedule 1, Figure 1. (4) detail measures to manage significant environmental impacts with regard to coastal processes and sediment movement as a result of the development. (5) determine trigger levels for implementation of management measures to ensure Condition 7-1 is met. (6) identify management measures to be implemented in the event that criteria identified required by Condition 7-2(5) have been exceeded.

Entire document

7-3 The proponent shall implement the approved Environmental Management and Monitoring Plan required by Conditions 7-2, unless otherwise approved by the CEO

Entire document

7-4 In the event that monitoring required by Condition 7-2 indicates trigger criteria have been exceeded, the proponent shall investigate to determine the likely cause(s) and provide a report that describes the investigation to the CEO within 10 days along with a description of the corrective management actions to be taken.

Section 3.1.6, Section 3.2.6, Section 3.3.6


Ministerial Statement 990 Condition Section in EMMP

7-5 The proponent shall implement the management actions identified in Condition 7-4 until the CEO determines that the remedial actions may cease.

Section 3.1.6, Section 3.2.6, Section 3.3.6

7-6 The proponent shall review the Environmental Management and Monitoring Plan annually, and revise where required, or as directed by the CEO. Section 4

7-7 The proponent shall implement the approved revisions of the Environmental Management and Monitoring Plan required by Condition 7-6 until advised otherwise by the CEO.

Section 4

7-8 The Proponent shall make the Environmental Management and Monitoring Plan, required by 7-2 publicly available in a manner approved by the CEO.

Section 5

Note: 1. EMMP = Environmental Monitoring and Management Plan, CEO = Chief Executive Officer of the Office of the

Environmental Protection Authority

2.4 Rationale and approach of the EMMP This document reflects the requirements of several conditions in Statement 990. The EMMP aims to ensure the breakwater reconfiguration is effective in enhancing natural coastal processes, and outlines what maintenance works may be required to ensure optimal performance of the coastal structures and minimise impacts on the environment in the PGCMA. The maintenance works (as described in Section 2.1) will be carried out in accordance with the EMMP and campaign-specific Environmental Management Plans (EMPs) to ensure minimal impact on the environment. The following sections provide background information and details on the Port Geographe development that have been used to develop the management approach for this EMMP. Results of baseline studies, modelling investigations, and reviews of historic and recent datasets have been used to inform the management approach for meeting the condition environmental objectives stated in Section 1. The section below also outlines a number of assumptions and uncertainties associated with the development and the proposed management approach. The management actions, management targets, and monitoring commitments in the subsequent sections of this EMMP are aligned with the overall management approach presented below.

2.4.1 Baseline studies A number of technical studies have been completed in the Geographe Bay region that help to provide an understanding of the possible impacts of the reconfiguration of the Port Geographe coastal structures on the existing environment, hydrodynamics, and natural coastal processes. Modelling studies and environmental, metocean, and engineering investigations completed over a number of years, have informed the monitoring and management approach for this EMMP (Table 2.4). Brief summaries of the results of these studies are provided below.

Table 2.4 Environmental, metocean, and engineering studies completed for the Port Geographe coastal structures development

Study type Organisation (and reference) Timeframe Key outcomes

Seagrass wrack dynamics in Geographe Bay

The University of Western Australia Seashore Engineering Pty Ltd BMT JFA Consultants Pty Ltd (Oldham et al. 2010, Pattiaratchi et al. 2011, Seashore Engineering 2014, BMT JFA 2015a)

2010–2015

Wrack accumulation in large quantities on Geographe Bay beaches is a natural occurrence

Seagrass wrack is generally removed from the beaches when the offshore supply of available seagrass is exhausted

Average accumulation of wrack on beaches west of Port Geographe is ~60 000–80 000 m3 per annum



Hydrogen sulfide (H2S) generation

ChemCentre The University of Western Australia Seashore Engineering Pty Ltd (ChemCentre 2010, Oldham et al. 2010, Seashore Engineering 2015)

2010–2014

H2S generation when large accumulations of wrack in nearshore saturated zone

Some exceedances of H2S guideline levels during previous bypassing campaigns with northerly winds

Port Geographe Sand and Seagrass Wrack Modelling Study

The University of Western Australia (Pattiaratchi & Wijeratne 2011)

2011

Curved breakwater configuration would accelerate and enhance wrack and sand transport processes

Optimum performance of the reconfiguration will be achieved once adjacent beach profiles and offshore bathymetry stabilise around the new structures

Maintenance works will shift from bypassing of sand and wrack to management of harbour entrance channel accumulations

Port Geographe harbour entrance channel flushing

The University of Western Australia (Pattiaratchi & Wijeratne 2016)

2016

The modelled e-folding times for the existing configuration of the coastal structures ranged from three days (close to the entrance to the artificial waterways) to ~20 days (for locations furthest from the entrance to the waterways)

Depth variations in the entrance channel caused a larger difference in the e-folding times between entrance configurations of -1.8 m chart datum (CD) and -1.3 m CD

Movements of particles inside the artificial waterways were strongly affected by tidal and seiche-induced currents

Shoreline movement and sediment transport in Geographe Bay

Riedel & Byrne Consulting Engineers Pty Ltd Damara WA Pty Ltd Shore Coastal Pty Ltd Seashore Engineering Pty Ltd BMT JFA Consultants Pty Ltd (Riedel & Byrne 1990, Damara WA 2010, 2011; Shore Coastal 2010, 2014; Seashore Engineering 2014, BMT JFA 2015b)

1941–2015

Historical shoreline movement highly dynamic

Predominantly eastward alongshore sediment transport

Sand supply from offshore Wonnerup sand bar

Sediment budget for Port Geographe indicates 20 000–65 000 m3 naturally bypassed per year

Metocean conditions

BMT JFA Consultants Pty Ltd (BMT JFA 2015c)

2014

Eastward surface currents across the Port Geographe development

Ebb and flood tide currents in the harbour entrance channel show oscillations of 30–40 min periods

Sediment and wrack quality

BMT Oceanica Pty Ltd (Oceanica & BMT JFA 2012, Oceanica 2013, BMT Oceanica 2014a, 2015a)

2012–2015

Sediment and wrack material within the PGCMA is generally clean and contains no contaminants at levels of concern



Environmental monitoring during maintenance works

BMT JFA Consultants Pty Ltd BMT Oceanica Pty Ltd (BMT JFA 2015d,e)

2012–2014

Seagrass meadow edge changes during capital and maintenance works within expected natural variability

Minor impacts on marine environmental quality and recreational amenity from temporary/localised increased water column turbidity

Metocean conditions Wave and current measurements were collected at three locations in the Port Geographe development and using GPS drogues from October–December 2014 following the breakwater reconfiguration (BMT JFA 2015c). Current measurements outside of the harbour entrance channel showed evidence of ebb and flood tides in addition to predominantly easterly nearshore currents along the coast. Wind conditions and tides were found to influence currents and occasional long periods of easterly flow along the coast (BMT JFA 2015c). Within the inner entrance channel and the Port Geographe canals, ebb and flood tide currents were aligned with the channel direction. A consistent oscillation at 30–40 minutes was measured at the inner entrance channel, with initial observations suggesting this is related to periods of increased swell waves (BMT JFA 2015c).

Shoreline movement Shoreline movement along Geographe Bay is highly dynamic, being influenced by coastal structures, offshore sandbars, drain outlets and variability in climatic conditions. Prior to construction of the Port Geographe development, the erosion from updrift groyne fields and the eastward migration of salients (typically associated with large offshore sand bars) influenced the shoreline in the vicinity of Port Geographe (Shore Coastal 2010, Damara WA 2011). The construction of Port Geographe in the late 1990s introduced the requirement for the alongshore sediment supply to downdrift beaches in the Wonnerup area to be provided by mechanical sand bypassing. Modelling by The University of Western Australia (UWA) found that the 2013/2014 reconfiguration of the Port Geographe breakwaters and re-alignment of the adjacent beaches would facilitate the eastward movement of sediment across the development once the Western Beach was saturated with sand and the new equilibrium beach profile was achieved (see below for more detail; Pattiaratchi & Wijeratne 2011).

Sediment transport Sediment transport rates across Geographe Bay are influenced by the direction of storm events and the interaction with varying coastal orientations and exposure (Damara WA 2011). There are summer/winter cycles in cross shore sediment transport in Geographe Bay with onshore transport in summer and offshore transport in winter (Damara WA 2010). This leads to the formation of beach erosion scarps and offshore sand bars over winter, with gradual onshore migration of the sand bar and restoration of the beach profile in summer (Damara WA 2010). A sediment budget for Port Geographe was developed using aerial imagery of Geographe Bay from 1941 to 2008 (Damara WA 2011). This analysis concluded that 20 000–30 000 m3 was bypassed eastwards at Port Geographe annually. A sediment budget of Wonnerup found that the Wonnerup sand bar feeds 25 000–35 000 m3 into the Wonnerup area annually; there is 15 000–20 000 m3 of eastward alongshore sediment supply into Wonnerup annually; and 40 000–50 000 m3 of eastward alongshore sediment transport out of the Wonnerup area annually.


Historical estimates of the required bypassing volumes at Port Geographe are based on annual longshore sediment transport rates varying from 20 000–65 000 m3. Between 2009 and 2012 an average of ~55 000 m3 of sand per annum was removed from the Western Beach and deposited at Wonnerup Beach during bypassing campaigns (BMT JFA 2015b). During the management of multiple dredging and sand bypassing campaigns at Port Geographe over recent years, specialist consultants have estimated that the average alongshore sediment transport rate is 65 000 m3 per annum (Seashore Engineering 2014, BMT JFA 2015b).

Wrack and sand transport modelling The recommended layout of the Port Geographe breakwater reconfiguration was modelled by UWA to determine whether it would accelerate and enhance wrack and sand transport processes, and reduce seagrass wrack accumulation (Pattiaratchi & Wijeratne 2011). The modelling exercise found the following: Natural bypassing of sand and seagrass wrack from west to east across the development can

occur once the Western Beach is saturated with sand. The performance of the reconfiguration will not be optimised until this occurs.

Occasional trapping of small quantities of seagrass wrack may occur from time to time across the development.

The recommended layout will cause the least amount of siltation in the harbour entrance channel compared to other reconfiguration options.

The design of the eastern end of the revetment improves conditions that previously caused erosion to the western end of Wonnerup Beach.

The reconfiguration will alter the coastal management focus from bypassing of seagrass wrack and sediment from the Western Beach to sediment management within the harbour entrance channel.

Harbour entrance channel modelling Hydrodynamic modelling studies have been completed by UWA to understand the influence of obstructions within the harbour entrance channel on water exchange and flushing (Pattiaratchi & Wijeratne 2016). The study modelled four different scenarios for the cross sectional area of the Port Geographe harbour entrance channel with depths at -2.8 m chart datum (CD; the design depth of the channel), -2.3 m CD, -1.8 m CD and -1.3 m CD. The study found that there was a substantial change in flushing and water exchange characteristics in the artificial waterways between the results from the -1.8 m CD and -1.3 m CD scenarios. Mean tidal amplitudes within the artificial waterways decreased by 5% for the -1.8 m CD scenario and by 15% for the -1.3 m CD scenario, when compared with the modelled results from the scenario with a design depth of -2.8 m CD. E-folding flushing times increased by 12% for the -1.8 m CD scenario and 35% for the -1.3 m CD scenario when compared with the modelled results from the scenario with a design depth of -2.8 m CD.

Nearshore bathymetry Since 2013, the nearshore bathymetry in the vicinity of Port Geographe has been influenced by the reconfiguration works. Changes observed from comparison of pre- and post-reconfiguration hydrographic surveys have shown widening of the Western Beach, re-alignment of the breakwaters, relocation and reorientation of the navigable entrance channel, release of sediment trapped in pocket beaches and the disposal of sediments in offshore, nearshore and beach areas (BMT JFA 2015e). A post-construction and beach nourishment hydrographic and topographic survey was completed in November 2014 across the entire PGCMA. This data is considered to be the initial benchmark


survey and will be used to assess future performance of the reconfigured coastal structures and comparison with future surveys will assist with identifying the need for maintenance works.

Benthic habitats The benthic habitat within Geographe Bay is predominantly seagrass beds (Oldham et al. 2010). The most common seagrasses within Geographe Bay are Posidonia australis, which covers 60% of the bay, and Amphibolis antarctica (Oldham et al. 2010). Seagrass meadows are present ~600 m offshore of the Port Geographe development (outside of the PGCMA), with some smaller patches of seagrass closer to shore (Figure 2.1). The remaining substrate within Geographe Bay is typically bare sand, with some patches of shallow limestone outcrops (DAL et al. 1995, DEC 2013). Seagrasses within Geographe Bay shed their leaves annually and these leaves are stored offshore in seagrass meadows and unvegetated zones during spring, summer and autumn (Oldham et al. 2010). During storms in late-autumn and winter each year, the leaves are transported inshore and large quantities of wrack are deposited on Geographe Bay beaches as a result of high water levels (Oldham et al. 2010). It is estimated that 32 600–35 200 tonnes of seagrass wrack is generated annually in Geographe Bay (Oldham et al. 2010). Wrack will usually remain on the beach for days or weeks until a subsequent storm transports the wrack alongshore. Smaller, thin aggregations of seagrass wrack below high water level are likely to be moved naturally while larger aggregations (>1 m) above high water level are only likely to move during storm events and high water periods such as spring tides (Oldham et al. 2010). Seagrass wrack is generally removed from the beaches when the offshore supply of available seagrass is exhausted (Pattiaratchi et al. 2011). Physical and chemical degradation of the material takes place as the wrack is transported on and off beaches, with nutrients ultimately returned to the marine environment. During the management of multiple wrack bypassing campaigns at Port Geographe over recent years, specialist consultants have estimated that the average accumulation of wrack on the beaches in the western section of the PGCMA has previously been in the order of ~60 000–80 000 m3 per annum (Seashore Engineering 2014, BMT JFA 2015a).

Hydrogen sulfide generation The Department of Health (DoH) provides odour guidelines relating to human health effects from exposure to H2S (Table 2.5). The DoH notes that the 2 ppm H2S limit is associated with bronchial effects in some asthmatics. The other limit values include safety margins and therefore an exceedance does not necessarily mean a health consequence (DoH 2015).

Table 2.5 Recommended hydrogen sulfide exposure limits for public protection

Limit (ppm) Averaging timeframe1

2 30 minutes

0.1 24 hours

0.014 90 days Source: DoH (2015)

Note: 1. The averaging timeframe is the time over which the measured level of H2S in air is averaged, and relates to

potential short- or long-term effects Monitoring of H2S generation during wrack bypassing works has been completed since 2008. During maintenance activities (such as mechanical bypassing), large quantities of H2S can be released over a short period of time which can potentially result in adverse health effects (ChemCentre 2010). Investigations by Oldham et al. (2010) found that H2S production is likely to


be greatest in accumulations of fresh seagrass wrack within the nearshore saturated zone. Data collected from 2010–2014 was examined to determine past exceedances of DoH guidelines during the works (Seashore Engineering 2015). The review found three recorded occasions where the DoH 30 minute guideline of 2.0 ppm H2S was exceeded. These three occasions coincided with light northerly winds during the bypassing works (Seashore Engineering 2015). There were up to 11 recorded occasions where the 24 hour guideline of 0.1 ppm H2S was exceeded, though some of the 2010 exceedances were considered to be associated with instrument/calculation error (Seashore Engineering 2015).

Water and sediment quality Geographe Bay generally experiences high water clarity, however episodes of naturally high levels of turbidity occur between autumn and spring due to the mobilisation of wrack and sediment into the water column during storm events. Sediment and wrack sampling and analyses have been completed on numerous occasions within the PGCMA to assess for elevated levels of contaminants: wrack sampled from the harbour entrance channel in January 2012 prior to maintenance

dredging works (Oceanica & BMT JFA 2012) sediment sampled from the Port Geographe marina and proposed capital dredging channel

and breakwater footprint in December 2012 (Oceanica 2013) sediment sampled from the Port Geographe canals in May 2014 for proposed maintenance

dredging (BMT Oceanica 2014a) sediment sampled from the Western Beach, nearshore & offshore areas of the PGCMA, and

Wonnerup Beach in August 2015 for proposed maintenance dredging and bypassing works (BMT Oceanica 2015a).

All of the sampling results indicated that the sediments and wrack were generally clean and concentrations of metals, organotins, and hydrocarbons were all below the relevant guidelines (Oceanica & BMT JFA 2012, Oceanica 2013, BMT Oceanica 2014a, BMT Oceanica 2015a).

Environmental monitoring during works The environmental impact assessments prepared for previous maintenance dredging and bypassing campaigns identified an increase in water column turbidity and smothering of seagrass meadows during offshore disposal as the key environmental issues that could arise during the campaigns (Oceanica 2013, BMT Oceanica 2014a, 2015a). These issues were actively monitored and managed during the previous maintenance campaigns in accordance with campaign-specific Dredging Environmental Management Plans (BMT Oceanica 2014b,c).

The bypassing and capital and maintenance dredging close-out reports (BMT JFA 2015d,e) describe the results of the environment monitoring during the works and confirmed that none of the above issues resulted in an adverse environmental impact. Turbidity monitoring indicated that considerable reductions in water clarity at the dredging and disposal sites recovered within a few days (BMT JFA 2015d,e). Monitoring of the seagrass meadows in the vicinity of the offshore disposal area indicated some areas of change in the seagrass meadow edge. After detailed analysis of multi-beam back scatter data from 2013–2014, the changes were found to be within the expected natural variability of seagrass movements and/or likely to be caused by natural physical disturbances, such as storms, rough conditions or localised currents (BMT JFA 2015e).

2.4.2 Key assumptions and uncertainties There are a number of key assumptions and uncertainties associated with the reconfigured Port Geographe coastal structures and their ongoing management. They are primarily related to the


wrack and sand modelling completed prior to the reconfiguration works (Pattiaratchi & Wijeratne 2011, Section 2.4.1), and the ongoing maintenance requirements of the development. It is anticipated that the reconfiguration will enhance the natural coastal processes of wrack and sediment movement, and facilitate adequate water exchange through the harbour entrance channel as predicted by the modelling study (Pattiaratchi & Wijeratne 2011, 2016; Section 2.4.1). If this occurs, then it is expected that minimal maintenance works will be required, and in some years, no maintenance works will be needed as the reconfiguration is performing as designed under typical metocean conditions. If any maintenance works are needed to fulfil the DoT's commitments under Statement 990, it is expected that these works will be of small-scale and short duration, and therefore significant environmental impacts are not expected (based on results of environmental monitoring completed for previous maintenance dredging and bypassing campaigns at Port Geographe, Section 2.4.1).

It is assumed from the results of the modelling study (Pattiaratchi & Wijeratne 2011) that:

The conceptual modelling work will translate to the physical site bringing about improved natural bypassing of sediment and wrack.

The reconfigured entrance channel delivers satisfactory flushing rates and water exchange to artificial waterways, maintaining water, sediment and biota quality.

There will be occasional trapping of small quantities of seagrass wrack across the development.

Drifting of sediment and wrack across the face of the development will not considerably impact water exchange between marine waters and the artificial waterways.

However some uncertainties remain:

Littoral drift capacity from the Western Beach to Wonnerup Beach is uncertain. It is uncertain to what degree H2S levels will be lowered by the reduction in saturated wrack

volumes on the Western Beach. Impacts of natural bypassing of sediment across the harbour entrance channel are uncertain

with some increase in sediment management expected due to siltation. Understanding of the project attributable impacts on wrack and sediment movement continue to improve as the natural coastal processes adjust to the reconfigured coastal structures. Adaptive monitoring and management is ongoing in three key areas of the PGCMA – the Western Beach, Wonnerup Beach and the harbour entrance channel – to assist with this understanding. Flexible and adaptive management and maintenance works will be required to manage these ongoing uncertainties.

2.4.3 Management approach The management of Port Geographe via this EMMP is focused on monitoring and management of three key components: seagrass wrack accumulations sediment movement harbour entrance channel depths. These three components are directly related to Conditions 4–7 in Statement 990, and are addressed in separate implementation sections of the EMMP (see Section 3). Each of the condition environmental objectives for seagrass wrack management, sediment movement and the harbour entrance channel are intended to be protective of all four EPA environmental factors


(and corresponding environmental objectives) described in Section 2.2. The risk-based management actions (see Sections 3.1.2, 3.2.2 and 3.3.2) and the reviewed and revised management actions (see Sections 3.1.5, 3.2.5 and 3.3.5) have been developed in accordance with the mitigation hierarchy (avoid, minimise, rehabilitate, offset; as per Section 6.3.2 of EAG17; EPA 2015) to ensure the condition environmental objectives (and the EPA environmental objectives) can be met (Section 2.4.4). The DoT recognises that there is some overlap of the monitoring and management actions between the three components, but for completeness, they are repeated in the individual component sections in Section 3 to ensure that it is clear how the condition environmental objective for each component (and ultimately the EPA environmental objective for each key environmental factor) will be met. There are potential impacts on the environment due to the presence of the Port Geographe coastal structures development. The DoT also recognises that completing maintenance works to alleviate these environmental impacts also has the potential to affect the environment. Therefore it is proposed that monitoring and management under the EMMP is implemented through a staged approach. This will allow for adequate consideration of the causal factors and determination of the most appropriate management responses. The first stage involves routine monitoring and management to determine the performance of the reconfigured coastal structures in enhancing natural coastal processes, and the need to complete maintenance works based on the results of the monitoring. The second stage of monitoring and management is required when maintenance works are deemed necessary, and it will focus on the potential impact on the environment during the maintenance works. Prior to the start of any maintenance works, an EMP specific to that maintenance campaign will be prepared based on the requirements detailed in this EMMP. This will include the currently defined monitoring and management requirements, but will also be amended, if necessary, to include additional requirements if future sampling or reviews indicate environmental or socio-economic issues that have not been previously identified.

2.4.4 Rationale for choice of management actions The management targets and management actions identified in the following sections of the EMMP have been developed based on the mitigation hierarchy (avoid, minimise, rehabilitate, offset; EPA 2015), and detailed reviews of the various baseline studies, modelling studies, and environmental, metocean, and engineering investigations completed for the Port Geographe development over a number of years (Section 2.4.1). Previous dredging, bypassing and nourishment campaigns completed at Port Geographe informed the various management targets for seagrass wrack management, sediment movement, and maintenance of the harbour entrance channel. For each of these campaigns, the close-out reports, results of environmental monitoring, and subsequent recommendations were reviewed to assist with developing the most appropriate management targets and management actions to ensure the impact on the environment from the presence of the Port Geographe coastal structures and any required maintenance works is firstly avoided, and then minimised as far as practicable. The staged management approach presented in Section 2.4.3 and the monitoring and management actions outlined in the EMMP are considered to be consistent with the DoT's Maintenance Dredging Environmental Management Framework (EMF; BMT Oceanica 2016, Appendix B) which applies to the DoT's ongoing statewide maintenance dredging program. The EMF is regularly reviewed, revised, and presented to environmental regulatory authorities (such as OEPA, Department of Parks and Wildlife, and the Department of Environment Regulation). The EMF has previously been acknowledged by the OEPA as a reasonable management framework for managing the maintenance activities being completed at Port Geographe from 2013–2016 (Appendix C).


The DoT has had a long association with the Port Geographe development and its environmental issues, and has been responsible for coastal management activities at the site since 2009. Based on that experience, previous studies, and the anticipated short-term duration and small-scale nature of the anticipated maintenance works, the choice of management actions and targets are considered to be appropriate to minimise and mitigate any environmental impacts, and ensure effective and efficient environmental management in order to achieve the environmental objectives stated in Section 2.2.


3. Implementation of the EMMP

3.1 Seagrass wrack management Seagrass wrack is deposited on Geographe Bay beaches and is transported naturally alongshore. The reconfigured Port Geographe coastal structures aim to enhance this natural transport of wrack alongshore. If wrack accumulates in large quantities against the coastal structures, the degradation of this material can release H2S and affect beach amenity and air quality. Management of wrack at Port Geographe may involve mechanical bypassing of material from the western side to the eastern side of the Port Geographe coastal structures.

3.1.1 Condition environmental objective Minimise the impact on the environment and human health due to trapped seagrass wrack.

3.1.2 Management actions Risk-based management actions (Table 3.1) have been identified and prioritised to achieve the condition environmental objective stated above (Section 3.1.1), and the EPA's environmental objectives (Section 2.2). These management actions focus the greatest management effort on minimising large accumulations of wrack on the Western Beach and reducing the impacts on seagrass meadows if maintenance works (mechanical bypassing and offshore disposal) are required. These management actions were specifically developed to minimise the impact on the environment and human health due to trapped seagrass wrack. The management actions assist with achieving the EPA's environmental objectives for the four key environmental factors (coastal processes, marine environmental quality, benthic communities and habitat, and air quality) by: ensuring littoral transport is not interrupted by monitoring coastal conditions and completing

maintenance works (key environmental factor: coastal processes) removing large accumulations of wrack on the coast that generate harmful levels of H2S (key

environmental factor: air quality) completing environmental monitoring of water and wrack quality for the maintenance works

(key environmental factor: marine environmental quality) completing environmental monitoring of turbidity during maintenance works to avoid and

minimise impacts to seagrass (key environmental factor: benthic communities and habitats) completing environmental monitoring of seagrass meadows for the maintenance works (when

disposing offshore) to avoid and minimise impacts to seagrass (key environmental factor: benthic communities and habitats).

These management actions will be implemented by the DoT for the Port Geographe development.


Table 3.1 Risk-based management actions that will be implemented to meet the condition environmental objective relating to seagrass wrack management

Environmental factor Environmental objective Impacts Management actions Risk-based priority Timing

Coastal processes

To maintain the morphology of the subtidal, intertidal and supratidal zones and the local geophysical processes that shape them

Interrupted littoral transport and accumulation of wrack

Implement coastal monitoring program Medium, adverse impact All project phases

Air quality

To maintain air quality for the protection of the environment and human health and amenity

Increased H2S levels from accumulated wrack Monitor H2S levels Medium, adverse impact Annually, Autumn to Spring

Marine environmental quality

To maintain the quality of water, sediment and biota so that the environmental values, both ecological and social, are protected

Reduced water clarity due to suspended sediment and wrack

Complete maintenance works in accordance with campaign-specific Environmental Management Plan Complete turbidity monitoring (nearshore & offshore disposal)

Low, adverse impact During maintenance works (nearshore and offshore disposal)

Benthic communities and habitat

To maintain the structure, function, diversity, distribution and viability of benthic communities and habitats at local and regional scales

Smothering/reduced light penetration to nearby seagrass meadows during maintenance works (with offshore disposal)

Complete maintenance works in accordance with campaign-specific Environmental Management Plan Complete turbidity monitoring (nearshore & offshore disposal) Complete seagrass meadow monitoring (offshore disposal)

Low, adverse impact Before, during, and after maintenance works (offshore disposal)

Note: 1. H2S = hydrogen sulfide


3.1.3 Management targets A number of management targets will be employed to measure and report against achievement of the condition environmental objective (Table 3.2). The outcomes of the Port Geographe capital dredging and breakwater reconfiguration project and previous wrack bypassing campaigns (Section 2.4) have informed the specific management targets.

Table 3.2 Management targets to measure the efficacy of management actions related to the seagrass wrack management condition environmental objective

Condition environmental objective

Minimise the impact on the environment and human health due to trapped seagrass wrack

Management target #1 Maintain natural beachfront wrack dynamics by ensuring less than 60 000 m3 of wrack is on the Western Beach by December each year

Management target #2 24 hour average H2S concentrations adjacent to the Western Beach do not exceed Department of Health guidelines of 0.1 ppm

Management target #3 Weekly (rolling 7-day) median light attenuation coefficient (LAC) values at impact sites do not exceed the 80th percentile of the reference sites for two consecutive weeks (if completing offshore disposal during maintenance works)

Management target #4 No change in position of seagrass meadow edge outside of the predicted zone of influence of the offshore disposal area beyond natural variability (if completing offshore disposal during maintenance works)

Note: 1. H2S = hydrogen sulfide gas, ppm = parts per million

3.1.4 Monitoring The purpose of the monitoring program is to inform, through the management targets, if the condition environmental objective is being achieved and when management actions will have to be reviewed and revised. This section describes how the DoT will complete routine monitoring to assess the performance of the Port Geographe coastal structures in promoting natural wrack dynamics, and also the monitoring that will be completed during maintenance works (if required) to determine whether the management targets are achieved.

Routine monitoring Routine monitoring tasks will be completed by the DoT. The DoT will implement a routine coastal monitoring program that will involve collecting, analysing and interpreting a number of coastal datasets over various timeframes (Table 3.3). Routine H2S monitoring will be completed between Autumn and Spring adjacent to the Western Beach (Table 3.3).

Table 3.3 Routine monitoring to measure the efficacy of management actions against the management targets for seagrass wrack management

Parameter Method Location Frequency

Seagrass wrack accumulation

Aerial photography

Western Beach (Freycinet Drive to Guerin Street)

At least once between Autumn and Spring each year

Site inspections by coastal technical advisor and photo monitoring

Approximately monthly, Autumn to Spring

Hydrographic and/or topographic surveys Three times per year


H2S monitoring using in situ measuring and data logging device

Adjacent to Western Beach Annually, Autumn to Spring



Wrack contaminant status

Wrack sampling and analysis as per DoT's Maintenance Dredging Environmental Management Framework (BMT Oceanica 2016, Appendix B)

Proposed wrack bypassing area on Western Beach

Every five years (or prior to maintenance works if period between works is greater than five years)

If the results of the routine monitoring indicate that the relevant management targets have not been met, then maintenance works (mechanical wrack bypassing) will likely be completed (as outlined in Section 2.1.1).

During-works monitoring Monitoring during maintenance works will be completed in accordance with the methods in Table 3.4 and described in detail in campaign-specific EMPs. Monitoring will focus on the key issues of water column turbidity, smothering and reduction of light for seagrass meadows, and H2S generation. If offshore disposal is undertaken, then monitoring of light levels over seagrass meadows will be done before, during and after works. Suitable locations of the impact and reference sites for light monitoring will be determined prior to offshore disposal. The impact sites will likely be in the seagrass meadow north of the offshore disposal area, and reference sites likely to the west of Port Geographe (Figure 2.2). The campaign-specific EMPs will also consider other environmental management measures to further reduce the impact of the works on the environment as per the EMF (BMT Oceanica 2016, Appendix B). Odour monitoring during maintenance works will be completed by the DoT adjacent to the Western Beach. This area is considered to pose the highest risk for exceedance of the DoH H2S guidelines. The DoT’s odour monitoring equipment will take continuous measurements during maintenance works. H2S levels recorded during periods of works will be compared to the DoH guidelines.

Table 3.4 During-works monitoring to measure the efficacy of management actions against the management targets for seagrass wrack management


Water column turbidity

Site photographs

Dredging and disposal site

Daily during works

Plume sketches1 Daily during works

Aerial photography Once during works

Secchi depths1 Offshore disposal area Daily during works (when offshore disposal occurring)



Adjacent to Western Beach Daily during works

Light attenuation In situ data loggers or hand-held meter

Impact sites in seagrass meadow adjacent to offshore disposal area, reference sites west of Port Geographe

Before, during and after offshore disposal

Seagrass meadow edge

Multi-beam surveys and/or towed video surveys

Seagrass meadow edge adjacent to offshore disposal area

Prior to and after offshore disposal

Note: 1. See Appendix D for example plume sketch and Secchi depth record templates


Weekly environmental monitoring checklists will be prepared during the maintenance works to identify any environmental issues, assess conformance with the campaign-specific EMP, and communicate any issues with collection of environmental monitoring data. Results of the during-works monitoring are reviewed frequently to determine whether there is any need to review and revise the management actions as per Section 3.1.5 below.

3.1.5 Review and revision of management actions Where the management target(s) are not met or exceeded, the DoT will review and revise the risk assessment and management actions and potentially identify additional management actions in accordance with the mitigation hierarchy (avoid, minimise, rehabilitate, offset; as per Section 6.3.2 of EAG17; EPA 2015), where necessary. During this process, the risks, key impacts, and associated management actions for seagrass wrack management will be reviewed and revised. The following are examples of revised and additional management actions for each of the impacts listed in Table 3.1: 1. Interrupted littoral transport and accumulation of wrack

i. Increase frequency of coastal monitoring program ii. Revise coastal monitoring program iii. Revise method/frequency/timing of maintenance works to reduce accumulated wrack

volumes iv. Issue community notice and install appropriate warning signs regarding conditions

2. Increased H2S levels from accumulation of wrack i. Push seagrass wrack to the back of the beach as far as practicable to reduce potential for

H2S generation ii. Revise H2S monitoring program iii. Issue community notice and install appropriate warning signs regarding potential odour

issues 3. Smothering or reduction of light penetration on nearby seagrass meadows during

maintenance works (with offshore disposal) i. Revise dredging and/or disposal methods and/or locations ii. Consider seagrass shoot density monitoring adjacent to offshore disposal area (and at

reference sites) in consultation with the OEPA iii. Seagrass meadow edge monitoring after end of maintenance works.

Reviewed and revised management actions will be implemented by the DoT to mitigate and manage any impacts so that the management targets and the condition environmental objective for seagrass wrack management are met.

3.1.6 Reporting Annual reporting The annual Statement of Compliance, required to be submitted by the DoT to fulfil Condition 3-6 of Statement 990, will state whether the condition environmental objective for seagrass wrack management has been met (Table 3.5). In the event that the condition environmental objective is not achieved during the reporting period, the Statement of Compliance will include a description of the effectiveness of revised and/or additional management actions implemented by the DoT and an analysis of the trends from the monitoring results. The annual Statement of Compliance will be submitted by 26 February each year in accordance with Condition 3-6 of Statement 990.


Table 3.5 EMMP reporting table for condition environmental objective relating to seagrass wrack management

Key environmental factors: Coastal processes, marine environmental quality, benthic communities and habitat, air quality (Ministerial Statement 990, Conditions 5-1, 6, 7)

Management targets for seagrass wrack management

Reporting on the management target Status

Management target #1: Maintain natural beachfront wrack dynamics by ensuring less than 60 000 m3 of wrack is on the Western Beach by December each year

Natural beachfront wrack dynamics were/were not maintained

■ YES ■ NO

Management target #2: 24 hour average H2S concentrations adjacent to the Western Beach do not exceed Department of Health guidelines of 0.1 ppm

Department of Health H2S 24 hour average guidelines were/were not exceeded

■ YES ■ NO

Management target #3: Weekly (rolling 7-day) median light attenuation coefficient (LAC) values at impact sites do not exceed the 80th percentile of the reference sites for two consecutive weeks (if completing offshore disposal during maintenance works)

Weekly median LAC values at impact sites did/did not exceed the 80th percentile of the reference sites for two consecutive weeks

■ YES ■ NO

Management target #4: No change in position of seagrass meadow edge outside of the predicted zone of influence of the offshore disposal area beyond natural variability (if completing offshore disposal during maintenance works)

Seagrass meadow edge position did/did not change beyond natural variability

■ YES ■ NO

Notes: 1. The status of achievement of the condition environmental objective is indicated by the following symbols:

■ = achieved ■ = not achieved 2. H2S = hydrogen sulfide, ppm = parts per million

Reporting on exceedances of management targets If a management target related to seagrass wrack management is exceeded (or not met), the CEO of the OEPA will be notified within ten days of identification of the exceedance. An investigation report will be prepared that describes the investigation into the exceedance and the corrective management actions in accordance with Condition 7-4 of Statement 990.

3.2 Sediment movement Alongshore sediment transport at Port Geographe is in a predominantly eastward direction. The reconfigured Port Geographe coastal structures aim to enhance this natural transport of sediment alongshore. If sediment accumulates in large quantities against coastal structures, it can indicate an interruption to natural sediment transport processes and result in erosion of downdrift beaches. Management of sediment at Port Geographe may involve mechanical bypassing of material from the western side to the eastern side of the development (see Section 2.1.2) to avoid/remediate erosion on downdrift Wonnerup Beach.

3.2.1 Condition environmental objective Minimise the impact on the environment and coastal processes due to interruption to sediment movement by the reconfigured coastal structures.

3.2.2 Management actions Risk-based management actions (Table 3.6) have been identified and prioritised to achieve the condition environmental objective stated above (Section 3.2.1), and the EPA's environmental objectives (Section 2.2). These management actions focus the greatest management effort on minimising project attributable erosion in the PGCMA and reducing the impacts on seagrass meadows if maintenance works (mechanical bypassing and offshore disposal, and/or


nourishment) are required. These management actions were specifically developed to minimise the impact on the environment and coastal processes due to the interruption to sediment movement by the reconfigured coastal structures. The management actions assist with achieving three of the EPA's environmental objectives by: ensuring littoral transport is not interrupted by monitoring coastal conditions and completing

maintenance works (key environmental factor: coastal processes) completing environmental monitoring of water and sediment quality for the maintenance

works (key environmental factor: marine environmental quality) completing environmental monitoring of turbidity during maintenance works to avoid and

minimise impacts to seagrass (key environmental factor: benthic communities and habitats) completing environmental monitoring of seagrass meadows for the maintenance works (when

disposing offshore) to avoid and minimise impacts to seagrass (key environmental factor: benthic communities and habitats).



Table 3.6 Risk-based management actions that will be implemented to meet the condition environmental objective relating to sediment movement


Coastal processes

To maintain the morphology of the subtidal, intertidal and supratidal zones and the local geophysical processes that shape them

Project attributable erosion at Wonnerup Beach

Implement coastal monitoring program Medium, adverse impact All project phases

Project attributable accretion at Western Beach

Implement coastal monitoring program

Low, adverse impact All project phases




Complete maintenance works in accordance with campaign-specific Environmental Management Plan Complete turbidity monitoring (nearshore and offshore disposal)





Complete maintenance works in accordance with campaign-specific Environmental Management Plan Complete turbidity monitoring (nearshore and offshore disposal) Complete seagrass meadow monitoring (offshore disposal)



3.2.3 Management targets A number of management targets will be employed to measure and report against achievement of the condition environmental objective (Table 3.7). The outcomes of the Port Geographe capital dredging and breakwater reconfiguration project and previous sediment bypassing campaigns (Section 2.4) have informed the specific management targets.

Table 3.7 Management targets to measure the efficacy of management actions related to the sediment movement condition environmental objective


Minimise the impact on the environment and coastal processes due to interruption to sediment movement by the reconfigured coastal structures

Management target #1

Maintain natural alongshore sediment movement by ensuring less than 30 000 m3 erosion within Wonnerup Beach (to the eastern extent of the Port Geographe Coastal Management Area) at the end of a rolling two-year period (when compared to the November 2014 survey)



3.2.4 Monitoring The purpose of the monitoring program is to inform, through the management targets, if the condition environmental objective is being achieved and when management actions will have to be reviewed and revised. This section describes how the DoT will complete routine monitoring to assess the performance of the Port Geographe coastal structures in promoting natural sediment transport, and also the monitoring that will be completed during maintenance works (if required) to determine whether the management targets are achieved.

Routine monitoring Routine monitoring tasks will be completed by the DoT. The DoT will implement a routine coastal monitoring program that will involve collecting, analysing and interpreting a number of coastal datasets over various timeframes (Table 3.8).

Table 3.8 Routine monitoring to measure the efficacy of management actions against the management targets for sediment movement


General beach condition


Beaches within and adjacent to PGCMA


Aerial photography PGCMA At least once between Autumn and Spring each year

Beach face and nearshore seabed elevations

Hydrographic and/or topographic surveys

PGCMA and surrounds (large-scale)

Annually (November or December)

PGCMA (small-scale) Biannually (in addition to large-scale survey)

Natural sediment transport volumes

Analysis of changes in hydrographic and/or topographic survey data

PGCMA Annually



Sediment contaminant status

Sediment sampling and analysis as per DoT's Maintenance Dredging Environmental Management Framework (BMT Oceanica 2016, Appendix B)

Proposed sand bypassing area on Western Beach

Every five years (or prior to maintenance works if period between works is greater than five years)

Note: 1. PGCMA = Port Geographe Coastal Management Area, DoT = Department of Transport If the results of the routine monitoring indicate that the relevant management targets have not been met, then maintenance works (mechanical sand bypassing/nourishment) will likely be completed (as outlined in Section 2.1.2).

During-works monitoring Monitoring during maintenance works will be completed in accordance with the methods in Table 3.9 and described in detail in campaign-specific EMPs. Monitoring will focus on the key issues of water column turbidity, and smothering and reduction of light for seagrass meadows. The campaign-specific EMPs will also consider other environmental management measures to further reduce the impact of the works on the environment as per the EMF (BMT Oceanica 2016; Appendix B). If odour monitoring is required (wrack is expected to be present in the material to be bypassed), monitoring will be completed as described in Section 3.1.4.

Table 3.9 During-works monitoring to measure the efficacy of management actions against the management targets for sediment movement



Site photographs Dredging and disposal site

Daily during works


Aerial photographs Once during works





Seagrass meadow edge Multi-beam surveys and/or towed video surveys





Adjacent to Western Beach

Daily during works (if wrack is expected to be present)

Note: 1. See Appendix D for example plume sketch and Secchi depth record templates Weekly environmental monitoring checklists will be prepared during the maintenance works to identify any environmental issues, assess conformance with the campaign-specific EMP, and communicate any issues with collection of environmental monitoring data. Results of the during-works monitoring tasks are reviewed frequently to determine whether there is any need to review and revise the management actions as per Section 3.2.5 below.


3.2.5 Review and revision of management actions Where the management target(s) are not met or exceeded, the DoT will review and revise the risk assessment and management actions and potentially identify additional management actions in accordance with the mitigation hierarchy (avoid, minimise, rehabilitate, offset; as per Section 6.3.2 of EAG17; EPA 2015), where necessary. During this process, the risks, key impacts, and associated management actions for sediment movement will be reviewed and revised. The following are examples of revised and additional management actions for each of the impacts listed in Table 3.6: 1. Project attributable erosion at Wonnerup Beach

i. Increase frequency of coastal monitoring program ii. Revise coastal monitoring program iii. Revise method/frequency/timing of sediment management works to minimise erosion

impacts 2. Project attributable accretion at Western Beach

i. Increase frequency of coastal monitoring program ii. Revise coastal monitoring program iii. Revise method/frequency/timing of sediment management works to minimise accretion

impacts 3. Smothering or reduction of light penetration on nearby seagrass meadows during


reference sites) in consultation with the OEPA iii. Seagrass meadow monitoring after end of maintenance works.

Reviewed and revised management actions will be implemented by the DoT to mitigate and manage any impacts so that the management targets and the condition environmental objective for sediment movement are met.

3.2.6 Reporting Annual reporting The annual Statement of Compliance, required to be submitted by the DoT to fulfil Condition 3-6 of Statement 990 will state whether the condition environmental objective for sediment movement has been met (Table 3.10). In the event that the condition environmental objective is not achieved during the reporting period, the Statement of Compliance will include a description of the effectiveness of revised and/or additional management actions implemented by the DoT and an analysis of the trends from the monitoring results. The annual Statement of Compliance will be submitted by 26 February each year in accordance with Condition 3-6 of Ministerial Statement 990.


Table 3.10 EMMP reporting table for condition environmental objective relating to sediment movement

Key environmental factors: Coastal processes, marine environmental quality, benthic communities and habitat (Ministerial Statement 990, Conditions 4–7)

Management targets for sediment movement Reporting on the management target Status

Management target #1: Maintain natural alongshore sediment movement by ensuring less than 30 000 m3 erosion within Wonnerup Beach (to the eastern extent of the Port Geographe Coastal Management Area) at the end of a rolling a two-year period (when compared to the November 2014 survey)

Natural alongshore sediment transport was/was not maintained

■ YES ■ NO



■ YES ■ NO


Seagrass meadow edge position did/did not changed beyond natural variability

■ YES ■ NO

Note: 1. The status of achievement of the condition environmental objective is indicated by the following symbols:

■ = achieved, ■ = not achieved

Reporting on exceedances of management targets If a management target related to sediment movement is exceeded (or not met), the CEO of the OEPA will be notified within ten days of identification of the exceedance. An investigation report will be prepared that describes the investigation into the exceedance and the corrective management actions in accordance with Condition 7-4 of Statement 990.

3.3 Harbour entrance channel Maintaining the cross sectional area of the Port Geographe harbour entrance channel will ensure that water exchange between Geographe Bay and the artificial waterways and canals is not restricted. Any substantial restriction of the cross sectional area of the harbour entrance channel as a result of sand and seagrass wrack accumulation may need to be managed through maintenance dredging campaigns.

3.3.1 Condition environmental objective Minimise the impact on the environment due to the restricted exchange of water through the harbour entrance channel.

3.3.2 Management actions Risk-based management actions (Table 3.11) have been identified and prioritised to achieve the condition environmental objective stated above (Section 3.3.1), and the EPA's environmental objectives (Section 2.2). These management actions focus the greatest management effort on minimising restricted exchange of water through the harbour entrance channel and reducing the impacts on seagrass meadows if maintenance works (maintenance dredging and offshore disposal) are required. These management actions were specifically developed to minimise the impact on the environment due to the restricted exchange of water through the harbour entrance channel. The management actions assist with achieving two of the EPA's environmental objectives by:


ensuring harbour entrance channel is not restricted by monitoring channel depths and completing maintenance dredging works (key environmental factor: marine environmental quality)

completing environmental monitoring of water and sediment quality for the maintenance works (key environmental factor: marine environmental quality)

completing environmental monitoring of turbidity during maintenance works to avoid and minimise impacts to seagrass (key environmental factor: benthic communities and habitats)

completing environmental monitoring of seagrass meadows for maintenance works (when disposing offshore) to avoid and minimise impacts to seagrass (key environmental factor: benthic communities and habitats).



Table 3.11 Risk-based management actions that will be implemented to meet the condition environmental objective relating to the harbour entrance channel




Restricted flushing and water circulation leading to poor water quality

Implement coastal monitoring program

Medium, adverse impact All project phases


Complete maintenance works in accordance with campaign-specific Environmental Management Plan Complete turbidity monitoring (nearshore and offshore disposal)





Complete maintenance works in accordance with campaign-specific Environmental Management Plan Complete turbidity monitoring (nearshore and offshore disposal) Complete seagrass meadow monitoring (offshore disposal)



3.3.3 Management targets A number of management targets will be employed to measure and report against achievement of the condition environmental objective (Table 3.12). The outcomes of the Port Geographe capital dredging and breakwater reconfiguration project, previous maintenance dredging campaigns and research completed by UWA on water exchange through the entrance channel (Pattiaratchi & Wijeratne 2016, Section 2.4.1) have informed the specific management targets.

Table 3.12 Management targets to measure the efficacy of management actions relative to the harbour entrance channel condition environmental objective


Minimise the impact on the environment due to the restricted exchange of water through the harbour entrance channel

Management target #1 Maintain cross sectional area of harbour entrance channel (below mean sea level) to no less than 120 m2 for two consecutive surveys.



3.3.4 Monitoring The purpose of the monitoring program is to inform, through the management targets, if the condition environmental objective is being achieved and when management actions will have to be reviewed and revised. This section describes how the DoT will complete routine monitoring to assess the performance of the Port Geographe coastal structures in maintaining the functionality of the harbour entrance channel, and also the monitoring that will be completed during the maintenance works (if required) to determine whether the management targets are achieved.

Routine monitoring Routine monitoring tasks will be completed by the DoT. The DoT will implement a routine coastal monitoring program that will involve collecting, analysing and interpreting a number of coastal datasets over various timeframes (Table 3.13).

Table 3.13 Routine monitoring to measure the efficacy of management actions against the management targets for the harbour entrance channel


Harbour entrance channel sand/wrack accumulation


Harbour entrance channel


Harbour entrance channel cross-sectional area

Hydrographic surveys Harbour entrance channel

Three times per year

General water quality Visual observations during site inspections

Harbour entrance channel and adjacent coastal waters


Sediment/wrack contaminant status

Sediment/wrack sampling and analysis as per DoT's Maintenance Dredging Environmental Management Framework (BMT Oceanica 2016, Appendix B)

Proposed dredging areas in harbour entrance channel

Every five years (or prior to dredging campaign if period between works is greater than five years)

Note: 1. DoT = Department of Transport


If the results of the routine monitoring indicate that the relevant management targets have not been met, then maintenance works (maintenance dredging) will likely be completed (as outlined in Section 2.1.3).

During-works monitoring Monitoring during maintenance works will be completed in accordance with the methods in Table 3.14 and described in detail in campaign-specific EMPs. Monitoring will focus on the key issues of water column turbidity, smothering and reduction of light for seagrass meadows, and H2S generation. The campaign-specific EMPs will also consider various other environmental management measures to further reduce the impact of the works on the environment as per the EMF (BMT Oceanica 2016, Appendix B). If odour monitoring is required (wrack is expected to be present in the material to be dredged), monitoring will be completed as described in Section 3.1.4.

Table 3.14 During-works monitoring to measure the efficacy of management actions against the management targets for the harbour entrance channel



Site photographs Dredging and disposal site

Daily during works


Aerial photographs Once during works





Seagrass meadow edge Multi-beam surveys and/or towed video





Adjacent to Western Beach

Daily during works (if wrack is expected to be present)

Note: 1. See Appendix D for example plume sketch and Secchi depth record templates Weekly environmental monitoring checklists will be prepared during the maintenance works to identify any environmental issues, assess conformance with the campaign-specific EMP and communicate any issues with collection of environmental monitoring data. Results of the during-works monitoring tasks are reviewed frequently to determine whether there is any need to review and revise the management actions as per Section 3.3.5 below.

3.3.5 Review and revision of management actions Where the management target(s) are not met or exceeded, the DoT will review and revise the risk assessment and management actions and potentially identify additional management actions in accordance with the mitigation hierarchy (avoid, minimise, rehabilitate, offset; as per Section 6.3.2 of EAG17; EPA 2015), where necessary. During this process, the risks, key impacts, and associated management actions for maintaining the harbour entrance channel will be reviewed and revised. The following are examples of revised and additional management actions for each of the impacts listed in Table 3.11:


1. Restricted flushing and water circulation leading to poor water quality i. Increase frequency of coastal monitoring program ii. Revise coastal monitoring program iii. Revise method/frequency/timing of maintenance works iv. Modify dredging depth and areas to reduce risk/likelihood of sediment/wrack

accumulation in harbour entrance channel v. Modify management of Western Beach sediment accumulation to reduce transport of

material into harbour entrance channel 2. Smothering or reduction of light penetration on nearby seagrass meadows during


reference sites) in consultation with the OEPA iii. Seagrass meadow monitoring after end of maintenance works.

Reviewed and revised management actions will be implemented by the DoT to mitigate and manage any impacts so that the management targets and the condition environmental objective for the harbour entrance channel are met.

3.3.6 Reporting Annual reporting The annual Statement of Compliance required to be submitted by the DoT to fulfil Condition 3-6 of Statement 990 will state whether the condition environmental objective for the harbour entrance channel has been met (Table 3.15). In the event that the condition environmental objective is not achieved during the reporting period, the Statement of Compliance will include a description of the effectiveness of revised and/or additional management actions implemented by the DoT and an analysis of the trends from the monitoring results.

The annual Statement of Compliance will be submitted by 26 February each year in accordance with Condition 3-6 of Ministerial Statement 990.

Table 3.15 EMMP reporting table for condition environmental objective relating to the harbour entrance channel

Key environmental factors: Coastal processes, marine environmental quality, benthic communities and habitat, air quality (Ministerial Statement 990, Condition 6, 7)

Management targets for the harbour entrance channel

Reporting on the management target Status

Management target #1: Maintain cross sectional area of harbour entrance channel (below mean sea level) to no less than 120 m2 for two consecutive surveys

Harbour entrance channel cross sectional area was/was not maintained

■ YES ■ NO



■ YES ■ NO


Seagrass meadow edge position did/did not changed beyond natural variability

■ YES ■ NO

Note: 1. The status of achievement of the condition environmental objective is indicated by the following symbols:

■ = achieved, ■ = not achieved


Reporting on exceedances of management targets If a management target related to the harbour entrance channel is exceeded (or not met), the CEO of the OEPA will be notified within ten days of identification of the exceedance. An investigation report will be prepared that describes the investigation into the exceedance and the corrective management actions in accordance with Condition 7-4 of Statement 990.


4. Adaptive Management and Reviews The DoT will implement adaptive management to learn from the monitoring and evaluation against management targets, and the implementation of revised management measures, to more effectively meet the three condition environmental objectives relating to seagrass wrack management, sediment movement, and the harbour entrance channel. The extent to which natural coastal processes will replicate the modelling results is yet to be realised, and will require ongoing monitoring to establish whether natural wrack and sediment movement are enhanced by the reconfigured coastal structures. Each year there will be natural variability in the coastal processes at Port Geographe. As a result, the interaction between natural sediment and seagrass wrack movement, and the reconfigured structures will change from year to year, requiring flexible and adaptive management approaches. The adaptive approach to be followed is described below: Systematic evaluation of routine monitoring data and comparison to benchmark data and

modelling results on an annual basis to assist with: assessing the proposal impacts and corresponding risk-based management actions verifying whether responses to the proposal impacts are similar to modelled predictions assessing the need to modify the November 2014 initial benchmark survey due to

equilibration of the coast to reconfigured coastal structures and/or larger scale coastal changes (for example climate change and sea level rise).

An increased understanding of the sediment and wrack transport dynamics and entrance channel flushing characteristics will arise from routine monitoring results and further data collection and research by the DoT. This will assist with reducing the various assumptions and uncertainties listed in Section 2.4.2, and for planning and refining maintenance works.

Contingency measures will be considered in campaign-specific EMPs to address unforeseen circumstances such as public complaints or environmental incidents such as hydrocarbon spills etc.

Any environmental issues and recommendations arising from the close-out reports from maintenance works will be reviewed in detail to improve management of future campaigns.

In accordance with Condition 7-6 of Statement 990, the EMMP will be reviewed annually, or as directed by the CEO, and revised by the DoT where required. In accordance with Condition 7-7 of Statement 990, the DoT will implement the approved revisions of the EMMP until advised otherwise by the CEO.

The annual review of the EMMP and preparation of the annual Statement of Compliance will assess the effectiveness of the management targets, management actions and general performance of the EMMP to identify the need to revise the management approach.

Amendments to the EMMP will also ensure best practice methods continue to be applied as knowledge, technology and requirements change. This may include amended or new environmental policies, new environmental guidelines, improved environmental understanding and outcomes following the annual Statement of Compliance reporting. Amendments to the EMMP are documented in Error! Reference source not found..

The EMMP references a number of appendices, external management plans and environmental frameworks (e.g. BMT Oceanica 2016; Appendix B). Any changes to these documents that may require subsequent changes to this document will be incorporated into the annual review of the EMMP.

The DoT may review the frequency and methods of the monitoring and maintenance programs outlined in this EMMP (to the approval of the CEO) if the reconfigured coastal structures are shown to be effective in minimising the impacts to the environment from


trapped wrack, the harbour entrance channel is flushing naturally and natural shoreline equilibrium is achieved on the Western Beach and Wonnerup Beach.

As outlined in the DoT’s approved Compliance Assessment Plan for Statement 990 (BMT Oceanica 2015b), and in accordance with the EPA’s Post Assessment Guideline 2 (EPA 2012a), the life of the proposal for the Port Geographe project is expected to extend to 2020 subject to demonstration that natural coastal processes have been reinstated at Port Geographe with minimal project attributable impacts. The need to continue implementation of this EMMP will be reviewed at this time in discussion with the CEO.


5. Stakeholder Consultation The Port Geographe capital dredging and breakwater reconfiguration project has involved extensive and ongoing stakeholder consultation with community, industry and government since 2004. The DoT has consulted with stakeholders while developing this EMMP to ensure consistency with the EPA's expectations on the principles of the environmental impact assessment process. This section provides a summary of consultation that has occurred for the Port Geographe project, which has involved extensive and ongoing stakeholder engagement with community, industry and government since 2004. The comments raised during consultations with stakeholders were considered in the development of the EMMP (Table 5.1). This consultation process is expected to be ongoing as the EMMP is reviewed and updated. The DoT will ensure the EMMP is made publicly available via the DoT’s website in accordance with EPA (2012b) and within 28 days of its approval by the CEO to fulfil Condition 7-8.

Table 5.1 Stakeholder consultation, comments and responses to the Port Geographe Environmental Monitoring and Management Plan

Organisation Type of consultation & date Stakeholder comments1 DoT response to comments

Port Geographe Community Consultation Forum

Regular meetings since 2009

Wonnerup Beach should remain a priority for replenishment and protection

Beach amenity is important to the community

Reduced levels of H2S from trapped seagrass remains a community priority

Entrance channel needs to remain navigable

Noted; and all elements addressed in this EMMP (Section 3)

City of Busselton (CoB) Meeting in April 2015

Protection of coastal infrastructure is essential

Desire for community input into EMMP management measures

CoB to integrate new lagoon area into bacterial sampling program

Coastal protection is integral part of the EMMP sediment management and beach nourishment activities (Section 3.2)

EMMP will be released for public comment and consultation

Noted; EMMP does not need to include bacterial sampling program in the new lagoon area

General public and stakeholders

Ongoing via dedicated email inbox and project phone line

Wonnerup Beach sand nourishment required to protect infrastructure

Protect Wonnerup foreshore vegetation

Post-reconfiguration coastal maintenance works on the Western Beach should be minimal

Coastal protection is integral part of the EMMP sediment management and beach nourishment activities (Section 3.2)

Vegetation will be managed primarily as per campaign-specific EMPs (Section 2.4.3)

Noted; need for works will be carefully considered (Section 2.1.2)


Organisation Type of consultation & date Stakeholder comments1 DoT response to comments

General public and stakeholders

Consultation on Draft EMMP July–August 2016

No works should be undertaken to bypass sand from the Western Beach to Wonnerup Beach.

Clarification provided in EMMP as to when bypassing sand from Western Beach may be necessary (Section 2.1.2)).

Alternate sand sources i.e. offshore sand bars and estuary inlet sand sources should be defined within the EMMP as possible sand sources.

Clarification provided in EMMP detailing the consideration of alternative sources of nourishment material (Section 2.1.2).

There should be no pumping or pushing of seagrass wrack off the Western Beach from December onwards.

Clarification provided in EMMP detailing the timing of wrack management, including the contingency measures that may be required if the management targets are not met (Section 2.1.1).

Future wrack and sand management works (mechanical intervention) in the PGCMA should be minimised and only undertaken when necessary.

The management targets within the EMMP have been carefully considered and developed to avoid unnecessary mechanical (human) intervention whilst meeting the environmental objectives.

Volume management targets for future wrack and sand management works (mechanical intervention) in the PGCMA should be lowered.

The monitoring tasks and the management targets within the EMMP have been carefully considered and developed to allow for necessary mechanical (human) intervention to meet the environmental objectives.

The PGCMA in which the EMMP is applicable should be aligned to management areas associated with the original development (under Ministerial Statement No. 391), thereby limiting the area of potential works and associated costs.

A PGCMA was established as part of Ministerial Statement No 990 which replaces and supersedes all previous conditions and commitments under Ministerial Statement No. 391. It is a regulatory requirement and is considered appropriate for the implementation of the Port Geographe Reconfiguration Project to ensure any potential project attributable impacts can be appropriately managed.

Notes: 1. The stakeholder comments listed here are a summary of the key comments received by the DoT that are directly

relevant to the EMMP. 2. DoT = Department of Transport, H2S = hydrogen sulfide gas, EMMP = Environmental Monitoring and

Management Plan, EMP = Environmental Management Plan.


6. References BMT JFA (2015a) Port Geographe Operational Maintenance Management Plan. Prepared for the

Department of Transport by BMT JFA Consultants Pty Ltd, Report Ref: R-300.12-14.3-1, Perth, Western Australia, February 2015

BMT JFA (2015b) Review of Long-shore Sediment Transport budgets – Technical Memo. Prepared for the Department of Transport by BMT JFA Consultants Pty Ltd, Report No. P-180.22-1, Perth, Western Australia, March 2015

BMT JFA (2015c) Port Geographe Metocean Monitoring Data Report. Prepared for the Department of Transport, Report No. R-300.12-14.3-1, Perth, Western Australia, January 2015

BMT JFA (2015d) Port Geographe Bypassing 2014 Closeout Report. Prepared for the Department of Transport by BMT JFA Consultants Pty Ltd, Report No. R-300.12-14.2-1 Rev0, Perth, Western Australia, February 2015

BMT JFA (2015e) Port Geographe Capital Dredging and Canal Maintenance Dredging 2013/14 Closeout Report. Prepared for the Department of Transport by BMT JFA Consultants Pty Ltd, Report No. R300.12-14.1-1, Perth, Western Australia, May 2015

BMT Oceanica (2014a) Port Geographe Marina Canals – Dredging Environmental Impact Assessment. Prepared for the Department of Transport by BMT Oceanica Pty Ltd, Report No. 924_03_001/3_Rev1, Perth, Western Australia, July 2014

BMT Oceanica (2014b) Port Geographe Marina Canals – Dredging Environmental Management Plan. Prepared for the Department of Transport by BMT Oceanica Pty Ltd, Report No. 924_03_001/2_Rev1, Perth, Western Australia, July 2014

BMT Oceanica (2014c) Port Geographe Wrack Bypassing and Beach Nourishment – Dredging Environmental Management Plan. Prepared for the Department of Transport by BMT Oceanica Pty Ltd, Report No. 924_05_001/1_Rev1, Perth, Western Australia, October 2014

BMT Oceanica (2015a) Port Geographe – Bypassing Environmental Impact Assessment. Prepared for the Department of Transport and BMT JFA Consultants Pty Ltd by BMT Oceanica Pty Ltd, Report No. 924_06_001/2_Rev0, December 2015

BMT Oceanica (2015b) Port Geographe Coastal Structures Compliance Assessment Plan – Ministerial Statement 990. Prepared for the Department of Transport by BMT Oceanica Pty Ltd, Report No 924_08_002/1_Rev0, Perth, Western Australia, November 2015

BMT Oceanica (2016) Department of Transport Maintenance Dredging – Environmental Management Framework. Prepared for the Department of Transport and BMT JFA Consultants Pty Ltd by BMT Oceanica Pty Ltd, Report No. 179_03_001/2_Rev0, Perth, Western Australia, March 2016

ChemCentre (2010) Report on the real time monitoring and management of hydrogen sulfide generation as a result of sea grass wrack bypass at Port Geographe, Report No. 09EH0421. Prepared for the Department of Transport, Perth, Western Australia, July 2010

DAL, UWA, WAWA (1995) Geographe Bay Study 1993–1995 Summary Report. Prepared for Water Authority of Western Australia by DA Lord & Associates and Centre for Water Research University of Western Australia, Department of Botany University of Western Australia, Water Authority of Western Australia (Southwest Region), Perth, Western Australia, June 1995


Damara WA (2010) Port Geographe Sand Management – Busselton Sediment Sampling. Prepared for the Department of Transport by Damara WA Pty Ltd, Report No. 95-01-Rev A, Perth, Western Australia

Damara WA (2011) Coastal Erosion Study: Assessment of Climate Change Impacts. Prepared for the Shire of Busselton by Damara WA Pty Ltd, Report No. 96-00-01, Busselton, Western Australia

DEC (2013) Ngari Capes Marine Park management plan 2013–2023, Management Plan Number 74. Department of Environment and Conservation, Perth, Western Australia, January 2013

DoH (2015) Department of Health – Hydrogen sulfide and public health http://ww2.health.wa.gov.au/Articles/F_I/Hydrogen-sulfide-and-public-health [Accessed 26 November 2015]

EPA (2012a) Post Assessment Guideline for Preparing a Compliance Assessment Plan. Office of the Environmental Protection Authority, Report No PAG 2, Perth, Western Australia, August 2012

EPA (2012b) Post Assessment Guideline for Making Information Publicly Available. Office of the Environmental Protection Authority, Report No PAG 4, Perth, Western Australia, August 2012

EPA (2013) Environmental Assessment Guideline for Environmental factors and objectives. Office of the Environmental Protection Authority, Report No EAG 8, Perth, Western Australia, June 2013

EPA (2015) Environmental Assessment Guideline for Preparation of management plans under Part IV of the Environmental Protection Act 1986. Environmental Protection Authority, Report No EAG 17, Perth, Western Australia, August 2015

Oceanica (2013) Port Geographe Capital Dredging 2013 – Dredging Environmental Impact Assessment. Prepared for the Department of Transport by Oceanica Consulting Pty Ltd, Report No. 924_02_001/1_Rev2, Perth, Western Australia, August 2013

Oceanica, BMT JFA (2012) Port Geographe 2012 Maintenance Dredging – Data Report. Prepared for the Department of Transport by Oceanica Consulting Pty Ltd and BMT JFA Consultants Pty Ltd, Report No. 924_001/2_Rev0, Perth, Western Australia, April 2012

Oldham CE, Lavery PS, McMahon K, Pattiaratchi C, Chiffings TW (2010) Seagrass wrack dynamics in Geographe Bay, Western Australia. Prepared for the Department of Transport, Report No. DPI 1062/07, Perth, Western Australia, April 2010

Pattiaratchi C, Wijeratne S (2011) Port Geographe Sand and Seagrass Wrack Modelling Study. Prepared for the Department of Transport by the University of Western Australia, Perth, Western Australia, May 2011

Pattiaratchi C, Wijeratne S (2016) Port Geographe reconfiguration: Effects of channel obstructions on flushing characteristics. Prepared for the Department of Transport by the University of Western Australia, Perth, Western Australia, January 2016

Pattiaratchi C, Wijeratne S, Bosserelle C (2011) Sand and seagrass wrack modelling in Port Geographe, south-western Australia. In Coasts and Ports 2011: Diverse and Developing: Proceedings of the 20th Australasian Coastal and Ocean Engineering Conference and the 13th Australasian Port and Harbour Conference. Engineers Australia, Perth, Western Australia, p. 564, September 2011

http://ww2.health.wa.gov.au/Articles/F_I/Hydrogen-sulfide-and-public-health


Riedel & Byrne (1990) Port Geographe Sand Bypassing and Coastal Management. Prepared by Riedel & Byrne Consulting Engineers Pty Ltd for Interstruct Holdings Pty Ltd, Rep No. R437, Perth, Western Australia

Seashore Engineering (2014) DOT400312-34 Independent Technical Advice (Construction) – Port Geographe: Sand Management. Prepared for the Department of Transport by Seashore Engineering Pty Ltd, Report No: SE003-16 Rev A, Perth, Western Australia, August 2014

Seashore Engineering (2015) Review of Historic Odour Monitoring Records. Prepared for BMT JFA Consultants Pty Ltd, Report No. SE016_03B, Perth, Western Australia, March 2015

Shore Coastal (2010) Geographe Bay Shoreline Movement. Prepared for the Shire of Busselton by Shore Coastal Pty Ltd, Busselton, Western Australia

Shore Coastal (2014) Busselton Coastal Management Plan Beach Monitoring (Year 1). Prepared for the City of Busselton by Shore Coastal Pty Ltd, Busselton, Western Australia

Appendix A

Ministerial Statement 990: Port Geographe Development Coastal Structures

Appendix B

Department of Transport Maintenance Dredging – Environmental Management Framework (March 2016)

Department of Transport Maintenance Dredging Environmental Management Framework

179_03_001/3_Rev0 March 2016

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Department of Transport Maintenance Dredging

Environmental Management Framework

Prepared for

Department of Transport and BMT JFA Consultants Pty Ltd

Prepared by

BMT Oceanica Pty Ltd

March 2016

Report No. 179_03_001/3_Rev0

Client: Department of Transport and BMT JFA Consultants Pty Ltd

Document history Distribution

Revision Author Recipients Organisation No. copies & format Date

A S Marshman B Hegge BMT Oceanica Pty Ltd 1 x docm 21/08/13

B S Marshman B Hegge BMT Oceanica Pty Ltd 1 x docm 03/12/14

C S Marshman T Ridgway BMT Oceanica Pty Ltd 1 x docm 14/05/15

D S Marshman P Wilkins K Ghaly

Department of Transport BMT JFA Consultants

1 x pdf 05/06/15

0 S Marshman

P Wilkins K Ghaly H Jacobs A Miller

Department of Transport BMT JFA Consultants OEPA DER

1 x pdf 22/03/16

Review

Revision Reviewer Intent Date

A B Hegge Technical review 14/02/14

B B Hegge Technical/editorial review 09/01/15

C T Ridgway Editorial review 04/06/15

D P Wilkins K Ghaly

Client review Client review

24/09/15 05/10/15

Quality Assurance

BMT Oceanica Pty Ltd has prepared this report in accordance with our Health Safety Environment Quality Management System, certified to OHSAS 18001, AS/NZS 4801, ISO 14004 and ISO 9001: 2008. Status This report is 'Draft' until approved for final release, as indicated below by inclusion of signatures from: (i) the author and (ii) a Director of BMT Oceanica Pty Ltd or their authorised delegate. A Draft report may be issued for review with intent to generate a 'Final' version, but must not be used for any other purpose.

Approved for final release:

Sarah Marshman Mark Bailey Date: 21/03/16 Date: 21/03/2016

Disclaimer This report has been prepared on behalf of and for the exclusive use of Department of Transport and BMT JFA Consultants Pty Ltd, and is subject to and issued in accordance with the agreed terms and scope between Department of Transport and BMT JFA Consultants Pty Ltd and BMT Oceanica Pty Ltd. BMT Oceanica Pty Ltd accepts no liability or responsibility for it in respect of any use of or reliance upon this report by any third party.

Copying this report without prior written consent of Department of Transport and BMT JFA Consultants Pty Ltd or BMT Oceanica Pty Ltd is not permitted.

© Copyright 2016 BMT Oceanica Pty Ltd

BMT Oceanica: DoT and BMT JFA: Department of Transport Maintenance Dredging Environmental Management Framework i

Contents

Acronyms and Definitions ......................................................................................................... v

Executive Summary ................................................................................................................. vii 1. Introduction ....................................................................................................................... 1

1.1 Background ............................................................................................................ 1

1.2 Purpose .................................................................................................................. 4

2. Maintenance Dredging Program ...................................................................................... 5

2.1 Determine maintenance dredging requirements ................................................. 5

2.2 Environmental impact assessment ...................................................................... 6

2.3 Approvals pathway ................................................................................................ 7

2.4 Confirm dredging scope and management .......................................................... 9

2.5 Stakeholder consultation ...................................................................................... 9

2.6 Supervision of maintenance dredging operation ................................................ 9

2.7 Maintenance dredging method ........................................................................... 10

3. Environmental Legislation .............................................................................................. 13

3.1 Environmental Protection Act 1986 .................................................................... 13

3.1.1 Environmental referral .................................................................................14

3.1.2 Level of assessment ....................................................................................14

3.2 Waterways Conservation Act 1976 ..................................................................... 15

3.3 Conservation and Land Management Act 1984 ................................................. 17

3.4 Contaminated Sites Act 2003 .............................................................................. 19

3.5 Aboriginal Heritage Act 1972 .............................................................................. 19

3.6 Environment Protection (Sea Dumping) Act 1981 ............................................. 20

3.7 Environment Protection and Biodiversity Conservation Act 1999 ................... 22

4. Environmental Guidelines .............................................................................................. 23

4.1 National Assessment Guidelines for Dredging.................................................. 23

4.1.1 Initial sediment screening (Phases I–II) .......................................................24

4.1.2 Further analysis (Phases III–V) ....................................................................26

4.2 Contaminated Sites Guidelines .......................................................................... 26

4.2.1 Ecological investigation levels and ecological screening levels ....................27

4.2.2 Health investigation levels ...........................................................................28

4.3 Acid Sulfate Soils Guidelines.............................................................................. 30

4.4 Australian and New Zealand Guidelines for Fresh and Marine Water Quality .................................................................................................................. 30

4.5 Landfill Waste Classifications and Definitions .................................................. 32

4.6 Sediment nutrient guidelines .............................................................................. 35

5. Environmental Impacts and Management ..................................................................... 36

5.1 Environmental factors and objectives ................................................................ 36

5.2 Significance framework ....................................................................................... 37

5.3 Environmental impacts of maintenance dredging operations .......................... 38

5.4 Environmental management ............................................................................... 40

ii BMT Oceanica: DoT and BMT JFA: Department of Transport Maintenance Dredging Environmental Management Framework

6. Environmental Monitoring of Dredging Operations .......................................................44

6.1 Pre-dredging sampling .........................................................................................44

6.2 During-dredging monitoring ................................................................................45

6.3 Reporting...............................................................................................................46

6.4 Monitoring summary ............................................................................................47

7. Review and Audits ...........................................................................................................48

8. References ........................................................................................................................49

BMT Oceanica: DoT and BMT JFA: Department of Transport Maintenance Dredging Environmental Management Framework iii

List of Figures

Figure 1.1 Maintenance dredging sites in Western Australia managed by the Department of Transport ....................................................................................... 3

Figure 2.1 Primary and secondary environmental approvals pathways .................................. 8

Figure 2.2 Cutter-suction dredge at Bandy Creek Boat Harbour ........................................... 10

Figure 2.3 Slurry pumping system (Slurrytrak) at Mandurah Entrance Channel ................... 11

Figure 2.4 Long-reach excavator at Ocean Reef Boat Harbour ............................................ 11

Figure 2.5 Trawling to remove wrack in Jurien Bay Boat Harbour ........................................ 12

Figure 3.1 Maintenance dredging sites and defined Waterway Management Areas and Catchment Management Areas ........................................................................... 16

Figure 3.2 Maintenance dredging sites with potential to affect Marine Parks ........................ 18

Figure 3.3 Environmental assessment for ocean disposal .................................................... 21

Figure 4.1 Assessment pathway for ocean disposal ............................................................. 24

Figure 5.1 Environmental Protection Authority's significance framework for the environmental impact assessment process ......................................................... 38

Figure 6.1 Decision tree for monitoring prior to dredging ...................................................... 45

Figure 6.2 Decision-tree for monitoring during dredging ....................................................... 46

List of Tables

Table 1.1 Facilities where the Department of Transport manages maintenance dredging (in geographical order from north to south) ............................................. 2

Table 2.1 Maintenance dredging frequency .......................................................................... 6

Table 3.1 Maintenance dredging sites within or adjacent to Marine Parks .......................... 17

Table 4.1 Screening Levels for sediment analytes from the National Assessment Guidelines for Dredging ....................................................................................... 25

Table 4.2 Contaminated Sites Guidelines ecological investigation levels for onshore disposal ............................................................................................................... 27

Table 4.3 Contaminated Sites Guidelines ecological screening levels for onshore disposal ............................................................................................................... 28

Table 4.4 Contaminated Sites Guidelines health investigation levels for onshore disposal ............................................................................................................... 29

Table 4.5 Texture-based acid sulfate soil Action Criteria ..................................................... 30

Table 4.6 Default trigger values for marine water physical and chemical stressors in tropical and south-west Australia for slightly disturbed ecosystems ..................... 31

Table 4.7 Trigger values for toxicants in marine water at alternative levels of species protection ............................................................................................................ 32

Table 4.8 Minimum number of sampling locations to support landfill waste classification .... 33

Table 4.9 Contaminant thresholds (for total concentration) for landfill wastes ..................... 33

Table 4.10 Australian Standard Leaching Procedures (ASLP) leachable concentration and the concentration limit (CL) values for waste classification ........................... 34

Table 5.1 Environmental factors and objectives used by the Environmental Protection Authority for assessing a proposal's impact on the environment .......................... 36

Table 5.2 Potential impacts associated with the Department of Transport's maintenance dredging operations ....................................................................... 39

Table 5.3 Description of consequences .............................................................................. 41

Table 5.4 Descriptions of likelihoods ................................................................................... 41

Table 5.5 Risk matrix .......................................................................................................... 41

iv BMT Oceanica: DoT and BMT JFA: Department of Transport Maintenance Dredging Environmental Management Framework

Table 5.6 Risk assessment of key biophysical and social issues that may be associated with the Department of Transport's maintenance dredging operations ............................................................................................................42

Table 6.1 Environmental monitoring summary table ............................................................47

BMT Oceanica: DoT and BMT JFA: Department of Transport Maintenance Dredging Environmental Management Framework v

Acronyms and Definitions

95% UCL A value that, when repeatedly calculated for randomly drawn subsets of size n, equals or exceeds the true population mean 95% of the time

ABA Acid-base accounting

AH Act Aboriginal Heritage Act 1972

ASLP Australian Standard Leaching Procedures

ASS Acid sulfate soils

CL Concentration limit

CS Act Contaminated Sites Act 2003

CSD Cutter suction dredge

CT Contaminated threshold

DAA Western Australian Department for Aboriginal Affairs

DDD Dichlorodiphenyldichloroethane

DDE Dichlorodiphenyldichloroethylene

DDT Dichlorodiphenyltrichloroethane

DEC Western Australian Department of Environment and Conservation

DEIA Dredging Environmental Impact Assessment

DEMP Dredging Environmental Management Plan

DER Western Australian Department of Environment Regulation

DoE Australian Department of the Environment

DoT Western Australian Department of Transport

DoW Western Australian Department of Water

DPaW Western Australian Department of Parks and Wildlife

EAG Environmental Assessment Guideline

EIL Ecological investigation level

EMF Environmental Management Framework

EPA Environmental Protection Authority

EPB Environmental Protection Bulletin

EP Act Environmental Protection Act 1986

EPBC Act Environment Protection and Biodiversity Conservation Act 1999

ESL Ecological screening level

HCB Hexachlorobenzene

HIL Health investigation level

LoR Limit of reporting

MCPA 2-methyl-4-chlorophenoxyacetic acid

MCBP 4-(4-chloro-o-tolyloxy)butyric acid

MPRA Marine Parks and Reserves Authority

NAGD National Assessment Guidelines for Dredging

vi BMT Oceanica: DoT and BMT JFA: Department of Transport Maintenance Dredging Environmental Management Framework

NEPC National Environment Protection Council

NtM Notice to Mariners

PAG Post Assessment Guideline

PAH Polycyclic aromatic hydrocarbon

PCB Polychlorinated biphenyl

PEP Project Execution Plan

PS Position Statement

SAP Sediment Sampling and Analysis Plan

TOC Total organic carbon

TPH Total petroleum hydrocarbons

TRH Total recoverable hydrocarbons

UCL Upper confidence limit

Wrack Seaweed or marine vegetation that is cast ashore

BMT Oceanica: DoT and BMT JFA: Department of Transport Maintenance Dredging Environmental Management Framework vii

Executive Summary

The Western Australian Department of Transport (DoT) is responsible for the management of a number of coastal facilities and small craft waterways around Western Australia (WA). A fundamental component of the DoT’s maintenance responsibilities is the requirement to retain navigable waters at these sites. The DoT, as the proponent of maintenance dredging activities at these sites, has ultimate responsibility to ensure the environment is protected under Part IV of the Environmental Protection Act 1986. The purpose of this Maintenance Dredging Environmental Management Framework (EMF) is to guide the DoT in the effective and efficient environmental management of their maintenance dredging operations. The EMF outlines the following: the DoT’s management of its maintenance dredging responsibilities the DoT’s maintenance dredging program and an outline of the typical works completed at the

various sites regulatory context for maintenance dredging at each facility environmental approvals pathways environmental and socio-economic issues typically arising from maintenance dredging

activities typical environmental management and contingency measures typical environmental monitoring. The DoT's maintenance dredging program is audited for compliance annually. Following the completion of each audit, the EMF shall be reviewed and updated to ensure it incorporates: amended or new environmental policies; new environmental guidelines; improved environmental understanding; and outcomes following the annual audit. This review schedule ensures the evolution and application of best practice environmental management to the DoT’s maintenance dredging program.

BMT Oceanica: DoT and BMT JFA: Department of Transport Maintenance Dredging Environmental Management Framework 1

1. Introduction

1.1 Background The Western Australian Department of Transport (DoT) is responsible for the management of a number of coastal facilities and small craft waterways around Western Australia (WA) (Figure 1.1). A fundamental component of the DoT’s maintenance responsibilities is the requirement to retain navigable waters at these sites and other regional channels. This is completed through an ongoing maintenance dredging program. This program is central to the viability of the State’s commercial fishing and marine tourism industry and to the safe use of waterways by recreational boat users. The statewide program is coordinated by a team that includes the: Principal and Superintendent (DoT) engineering and project management consultant environmental consultant dredging contractor. The DoT manages maintenance dredging (the removal of material from an ocean, estuary, river bed, beach or bank, including bypassing) at over 40 sites (Table 1.1, Figure 1.1). Twenty six of these maritime facilities are managed by the DoT, 14 of which have required maintenance dredging within the past 10 years. The authority for the DoT to carry out maintenance dredging works is given under Section 5(1) of the Marine & Harbours Act 1981. The DoT, as the proponent of maintenance dredging activities at these facilities, has ultimate responsibility to ensure the environment is protected under Part IV of the Environmental Protection Act 1986

(EP Act). In the past, the DoT has also assisted other agencies with management of maintenance dredging at the following additional sites: two commercial ports (Wyndham Port and Derby Port) Ocean Reef Boat Harbour (under management deed) for the City of Joondalup various regional waterways within the Swan River, Canning River, Peel Harvey Estuary and

Hardy Inlet Mandurah Entrance Channel and Dawesville Entrance Channel Collie River on behalf of South West Development Commission. The Coastal Infrastructure Business Unit of the DoT manages a rolling five year maintenance dredging program. The rate of natural siltation is typically dependent on the frequency and intensity of metocean events and is difficult to predict. Therefore the dredging program is based on historic dredging frequency, a review of hydrographic survey data and assessment of actual dredging requirements, and feedback from users at each facility.

2 BMT Oceanica: DoT and BMT JFA: Department of Transport Maintenance Dredging Environmental Management Framework

Table ‎1.1 Facilities where the Department of Transport manages maintenance dredging (in geographical order from north to south)

Region Site Facility

Kimberley Wyndham Port Port

Kimberley Derby Port Port

Pilbara Point Samson Boat Harbour (John's Creek) Small Boat Harbour

Pilbara Onslow Maritime Facility Channel and Harbour Basin

Gascoyne Exmouth Boat Harbour Small Boat Harbour

Gascoyne Coral Bay Maritime Facility Jetty

Gascoyne Carnarvon Boat Harbour Small Boat Harbour

Gascoyne Teggs Channel Channel

Gascoyne Denham Maritime Facility Channel and Harbour Basin

Mid West Kalbarri Maritime Facility Jetty

Mid West Murchison River Channel (Kalbarri) Channel

Mid West Port Gregory Maritime Facility Jetty

Mid West Geraldton Batavia Coast Marina Small Boat Harbour

Mid West Port Denison Boat Harbour Small Boat Harbour

Mid West Leeman Maritime Facility Jetty

Mid West Green Head Maritime Facility Jetty

Wheatbelt Jurien Bay Boat Harbour Small Boat Harbour

Wheatbelt Cervantes Maritime Facility Jetty

Wheatbelt Lancelin Maritime Facility Jetty

Metropolitan Two Rocks Marina Small Boat Harbour

Metropolitan Ocean Reef Boat Harbour Small Boat Harbour

Metropolitan Hillarys Boat Harbour Small Boat Harbour

Metropolitan Barrack Street Jetties Jetty

Metropolitan Fremantle Fishing Boat Harbour Small Boat Harbour

Peel Mandurah Entrance Channel Channel

Peel Sticks Channel Channel

Peel Murray and Serpentine River Channels Channel

Peel Yunderup Approach Channel Channel

Peel Point Grey Channel Channel

Peel Dawesville Entrance Channel Channel

South West Collie River Channel

South West Bunbury Casuarina Boat Harbour Small Boat Harbour

South West Port Geographe Channel Small Boat Harbour

South West Hardy Inlet Channel Channel

South West Augusta Maritime Facility Jetty

South West Augusta Boat Harbour Small Boat Harbour

Great Southern Albany Waterfront Marina Small Boat Harbour

Great Southern Emu Point Boat Harbour (Albany) Small Boat Harbour

Great Southern Bremer Bay Boat Harbour Small Boat Harbour

Goldfields/Esperance Hopetoun Maritime Facility Jetty

Goldfields/Esperance Bandy Creek Boat Harbour (Esperance) Small Boat Harbour


Figure ‎1.1 Maintenance dredging sites in Western Australia managed by the

Department of Transport


1.2 Purpose The DoT, as the proponent of maintenance dredging activities at these sites, has ultimate responsibility to ensure the environment is protected under Part IV of the EP Act. The purpose of this Environmental Management Framework (EMF) is to guide the DoT in the effective and efficient environmental management of their maintenance dredging operations. The EMF outlines the following: the DoT’s management of its maintenance dredging responsibilities the DoT’s maintenance dredging program and an outline of the typical works completed at the

various sites regulatory context for maintenance dredging at each facility environmental approvals pathway environmental and socio-economic issues typically arising from maintenance dredging

activities typical environmental management and contingency measures typical environmental monitoring. This EMF is intended to ensure that the DoT’s maintenance dredging activities are completed with due environmental care and transparency. The guidance is based upon the principles of: protection of the environment clear, relevant and practical identification of environmental issues efficient management and completion of environmental assessments as required. The maintenance dredging program continues to be audited annually to track compliance (Section 7). Following the completion of each audit, the EMF shall be reviewed and updated to ensure that it incorporates: amended or new environmental policies; new environmental guidelines; improved environmental understanding; and outcomes following the annual audit. This review schedule should ensure the evolution and application of best practice environmental management to the DoT’s maintenance dredging program.


2. Maintenance Dredging Program The DoT manages maintenance dredging via the following steps to ensure projects are progressed openly, effectively and with close regard to the social, environmental and safety issues: 1. determine maintenance dredging requirements 2. assess the environmental impacts and associated approvals pathways 3. confirm the dredging scope with the dredging contractor 4. complete stakeholder consultation 5. supervise the maintenance dredging operation and coordinate environmental monitoring 6. complete close-out reporting and capture lessons learnt.

2.1 Determine maintenance dredging requirements The DoT coordinates hydrographic surveys to support the maintenance dredging program. The frequency of hydrographic surveys at each site is determined from a consideration of the rate of sedimentation, the navigational risks, and feedback from users of the facility. Annual hydrographic surveys are typically done at 17 sites, and at another 14 sites hydrographic surveys are generally at a frequency of 2–5 years (Table 2.1). At a further five sites, hydrographic surveys are infrequent (>5 years; Table 2.1). The hydrographic survey data provides information on the form and stability of any previous disposal sites, the presence of significant accretion or erosion, and assists in prioritising areas for maintenance dredging. The hydrographic survey data is assessed, together with any input from users/operators, to determine the need for further action. This survey assessment is documented in a survey review document which recommends further actions that could include maintenance dredging or alternative methods to delay the maintenance dredging requirement (e.g. relocation of navigation aids). If maintenance dredging is required, then the most recent hydrographic survey shall be used to define the areas and volumes to be dredged. Several alternative disposal options should also be identified at this point. This planning work should also be informed by a review of the close-out reports from previous maintenance dredging campaigns at the site. This information is used for the preparation of scoping documentation for the dredging contractor and for the preparation of a Dredging Environmental Impact Assessment (DEIA; Section 2.2). The typical frequency of maintenance dredging at the DoT dredging sites is given in Table 2.1.


Table ‎2.1 Maintenance dredging frequency

Site Typical frequency

Wyndham Port Annual

Derby Port Infrequent

Point Samson Boat Harbour (John's Creek) Infrequent

Onslow Maritime Facility 5–10 years

Exmouth Boat Harbour 5 years (channel) 2–3 years (sand trap)

Coral Bay Maritime Facility No previous maintenance dredging

Carnarvon Boat Harbour 10 years

Teggs Channel 5–10 years

Denham Maritime Facility 7–10 years

Kalbarri Maritime Facility Infrequent

Murchison River Channel (Kalbarri) Annual

Port Gregory Maritime Facility Infrequent

Geraldton Batavia Coast Marina No previous maintenance dredging

Port Denison Boat Harbour Infrequent

Leeman Maritime Facility Infrequent

Green Head Maritime Facility Infrequent

Jurien Boat Harbour 5–10 years

Cervantes Maritime Facility Infrequent

Lancelin Maritime Facility 3–5 years

Two Rocks Marina Infrequent

Ocean Reef Boat Harbour Annual

Hillarys Boat Harbour No previous maintenance dredging

Barrack Street Jetties Infrequent

Fremantle Fishing Boat Harbour Infrequent

Mandurah Entrance Channel Annual

Sticks Channel No previous maintenance dredging

Murray and Serpentine River Channels 5–10 years

Dawesville Entrance Channel Annual

Point Grey Channel 5–10 years

Collie River Infrequent

Bunbury Casuarina Boat Harbour No previous maintenance dredging

Port Geographe Channel 2 years

Augusta Maritime Facility Infrequent

Hardy Inlet Channel 5–10 years

Albany Waterfront Marina Infrequent

Emu Point Boat Harbour Infrequent

Bremer Bay Boat Harbour Annual

Hopetoun Maritime Facility Infrequent

Bandy Creek Boat Harbour (Esperance) 2 years

2.2 Environmental impact assessment A DEIA should be prepared prior to commencement of the maintenance dredging works. The DEIA should outline the proposed dredging and disposal campaign; present the results of any environmental sampling; consider the potential environmental and socio-economic impacts of the proposed campaign; provide information on any stakeholder consultation that has been


completed; and recommend environmental monitoring and management measures to minimise any potential impacts of the campaign. Preparation of the DEIA requires an understanding of the various impact pathways and a consideration of the magnitude of these potential impacts versus natural variations experienced at the proposed dredging and disposal sites. The DEIA may be referred for formal environmental approval depending on the scale of the environmental and socio-economic impacts and the proposed location of the dredging and disposal works (see Section 2.3, Section 3.1, and Section 5). The DEIA is considered current for a period of five years after the environmental sampling is completed, but shall be briefly reviewed prior to each campaign (within the 5-year period) to ensure its suitability. However, the DEIA may require revision (within the 5-year period) if there has been any contamination events or major changes to the dredging or disposal method that could have an adverse impact on the environment.

2.3 Approvals pathway Most of the DoT maintenance dredging projects are not formally referred to the Environmental Protection Authority (EPA) as the dredging is of small-scale and occurs in already disturbed areas where no significant environmental impact is anticipated. Furthermore, there is generally strong community support for the dredging works. However, if significant adverse environmental impacts are anticipated, or there is a high level of stakeholder concern, then it is appropriate to refer the proposed works to the EPA under Part IV of the EP Act. There are a number of additional approvals that may be required (Figure 2.1, Section 3): if the proposed works are likely to impact on a matter of national significance, the proposal

needs to be referred to the Australian Department of Environment (DoE) under the Environmental Protection and Biodiversity Conservation Act 1999 (EPBC Act; with consideration of the bilateral assessment agreement)

if the proposed disposal site falls within State or Commonwealth waters (and not in Internal Waters), a Sea Dumping Permit from the DoE is required. The Sea Dumping Permit application process must commence prior to any sediment sampling and alternative disposal options must be investigated and documented

if the dredging or disposal site is in proximity to or within a Marine Park, the WA Department of Parks and Wildlife (DPaW) must be notified and a Lawful Authority may be required. This will involve consultation with the Marine Parks and Reserves Authority (MPRA)

if the dredging or disposal site falls within a Waterway Management Area managed by the WA Department of Water (DoW), then a Licence to Dredge is required (Figure 2.1)

if the dredging or disposal activities disturb or have the potential to create a contaminated site then liaison with the WA Department of Environment Regulation (DER) is required

if the dredging or disposal activities will disturb or remove native vegetation then a vegetation clearing permit from the DER is likely to be required.

In the case of emergency dredging works, safety issues may take precedence over environmental issues and the DoT Marine Safety Unit should be consulted.


Figure ‎2.1 Primary and secondary environmental approvals pathways


2.4 Confirm dredging scope and management The DoT has a long-term contract with a dredging contractor for the supply of dredging and related works for the DoT's coastal facilities. This contract includes a General Specification for Dredging which covers general requirements that are applicable to all sites which ensure the works are carried out with minimal environmental impacts. To manage the specific environmental aspects of each dredging campaign the Principal (DoT) shall prepare a Dredging Environmental Management Plan (DEMP), in consultation with the contractor. The DEMP should succinctly define the environmental monitoring program, management measures and management actions. The DEMP shall undergo a brief review (where appropriate) prior to each campaign to ensure its suitability. A full revision of the DEMP may be required if there are any major changes to the dredging or disposal method that have been deemed by the DEIA to have a potential impact on the environment. The contractor shall then prepare a Project Execution Plan (PEP) that describes the scope of dredging works, and shows how the environmental requirements of the DEMP shall be addressed.

2.5 Stakeholder consultation Prior to each dredging campaign, where appropriate, the relevant DoT Regional Coordinator and the DoT Regional Manager, and/or the Harbour Manager (if applicable) shall be notified of the works. The DoT shall also notify the local DPaW, the local DER, and the relevant local government authority of the works. Depending on the location, duration and scope of work, other consultation may be completed as follows: consultation with community and stakeholder groups such as surf clubs, sea rescue groups,

resident associations, commercial and recreational fishing associations consultation with Aboriginal Heritage groups placement of public information signage. All stakeholder consultation (verbal or written) shall be documented and uploaded to Pearl. If the dredging works are planned in a navigation area, a Notice to Mariners (NtM) shall be issued through the DoT Marine Safety Unit. A NtM is only required when works are being completed in a navigational area (e.g. NtM not required for Mandurah and Dawesville Entrance Channels, Ocean Reef bypassing).

2.6 Supervision of maintenance dredging operation When the environmental impact assessments are complete, relevant government authorities have been notified, and a DEMP and a PEP have been prepared, the dredging operation may commence. The DoT are responsible for the overall supervision of the dredging operation, including management and environmental monitoring. Weekly progress reports that include updates on dredging operations, site inspections and environmental monitoring results, are prepared by the engineering consultant for submission to the Principal. On completion of the dredging operation, the dredge is demobilised from site and a close-out report is prepared. The close-out report provides a summary of the maintenance dredging operation and environmental monitoring including any operational and/or environmental issues that arose. It shall also capture lessons learnt and recommendations for future dredging campaigns at the site. The close-out report provides an important reference for planning any future maintenance dredging works and should be completed within three months of completion of dredging.


2.7 Maintenance dredging method Many of the DoT's maintenance dredging projects are executed using a small cutter-suction dredge (CSD; Figure 2.2). The dredge uses a small rotating cutter-head on the end of a ‘ladder’ to loosen material off the seabed which is immediately recovered by a suction tube directly behind the cutter head. The material is then pumped to the disposal site via flexible floating or submerged pipelines. During dredging, the CSD is kept in position using anchors and/or spud poles. The main, or ‘working’ spud is used as a reaction point against which the dredge is moved forward and pushes the cutter head into the dredge cut. The cutter head of the dredge moves from one side of the cut to the other by winching on the anchors deployed either side of the dredge, causing the dredge to rotate around the main spud pole. A land-based excavator and slurry-pumping system is used at the Mandurah and Dawesville Entrance Channels to bypass large volumes of sediment annually (Figure 2.3). At other sites, land-based machinery is used and typically consists of a long-reach excavator, often working from a temporary bund or barge, with front end loaders and trucks on shore (Figure 2.4). Isolated high-spots may be removed using a trawl bar or plough and wrack1 material has also been removed from the seabed and water column at some sites using a trawl net (Figure 2.5).

Source: BMT JFA Consultants Pty Ltd (May 2013)

Figure ‎2.2 Cutter-suction dredge at Bandy Creek Boat Harbour

1 Seaweed or marine vegetation that is cast ashore.


Source: BMT JFA Consultants Pty Ltd (July 2013)

Figure ‎2.3 Slurry pumping system (Slurrytrak) at Mandurah Entrance Channel

Source: BMT JFA Consultants Pty Ltd (January 2013)

Figure ‎2.4 Long-reach excavator at Ocean Reef Boat Harbour


Source: BMT JFA Consultants Pty Ltd (November 2013)

Figure ‎2.5 Trawling to remove wrack in Jurien Bay Boat Harbour


3. Environmental Legislation It is preferred that potential environmental impacts are managed through the careful design and implementation of the dredging works to meet recognised environmental criteria. In this way, formal environmental assessment is often not required. In keeping with the EPA’s ‘General Guide for State Government Departments and Local Authorities (as Decision-Making Authorities)’, the DoT shall liaise with the appropriate local authorities regarding the impacts of their proposal (see Section 2.3). Formal approvals may be required if (Figure 2.1): significant environmental impacts are anticipated (Environmental Protection Act 1986) dredging is located within a Waterway Management Area (Waterways Conservation Act

1976) dredging is likely to impact on a Marine Park (Conservation and Land Management Act 1984) dredging is likely to disturb or create a contaminated site (Contaminated Sites Act 2003) dredging results in disturbance of Aboriginal heritage (Aboriginal Heritage Act 1972) dredged material is disposed to sea (Environment Protection (Sea Dumping) Act 1981) dredging will impact on a matter of national environmental significance (Environment

Protection and Biodiversity Conservation Act 1999). A number of the DoT maintenance dredging sites have previously received approval under the EP Act for facility construction and/or maintenance works. In these instances, further approval may not be required if the works were considered within the original approval. The relevant legislation and approval processes for each of the above Acts are summarised below.

3.1 Environmental Protection Act 1986 The Environmental Protection Act 1986 (EP Act) is the key legislation governing the requirement for environmental protection and management in WA including the assessment of the impacts of any proposed new works. The EP Act (mainly Part IV) together with its subsidiary Environmental Impact Assessment Administrative Procedures 2012 (EPA 2012), specifies the objectives and requisite procedures for environmental impact assessment of proposed works that must be complied with by all stakeholders including the proponent, the EPA and any other relevant party. The approach taken by the EPA during the Environmental Impact Assessment process has been documented by the EPA in a number of Environmental Assessment Guidelines (EAGs; formerly known as Guidance Statements). The EAGs of particular relevance to the DoT's maintenance dredging program include: Protection of Benthic Primary Producer Habitat in WA's Marine Environment (EAG3;

EPA 2009) Marine Dredging Proposals (EAG7; EPA 2011) Environmental Factors and Objectives (EAG8; EPA 2013a) Application of a Significance Framework in the EIA Process (EAG9; EPA 2013b) Protecting the Quality of Western Australia's Marine Environment (EAG15; EPA 2015a) Preparation of Management Plans under Part IV of the Environmental Protection Act 1986

(EAG17; EPA 2015b). The view of the EPA on various environmental or procedural matters are presented in a series of Environmental Protection Bulletins (EPBs; formerly known as Position Statements) that are applicable to the DoT's maintenance dredging program, such as EPB No. 1 Environmental Offsets – Biodiversity, and also Position Statements (PSs) and PS2 Environmental Protection of Native Vegetation in WA.


The Office of the EPA (OEPA) has prepared a number of Post Assessment Guidelines (PAGs) to assist proponents to meet their statutory requirements under Part IV of the EP Act. The following PAGs are relevant to the DoT's maintenance dredging program: Preparing an Audit Table (PAG1) Preparing a Compliance Audit Plan (PAG2) Preparing a Compliance Assessment Report (PAG3). All of the EAGs, PAGs, EPBs, and PSs are available on the EPA website (www.epa.wa.gov.au).

3.1.1 Environmental referral Under Section 38(1) of the EP Act (Part IV), where a proposed project development is likely to have a significant impact on the environment, the proponent must refer the proposal to the EPA for a decision on whether it requires formal environmental impact assessment, and if so, at what level of assessment. The DoT shall refer maintenance dredging projects to the EPA if they are anticipated to have a significant effect on the environment and no environmental approvals have previously been obtained. It may also be appropriate to refer a project if there is a high level of community/stakeholder concern. When referring a project it is necessary to submit a referral pro-forma (obtained from www.epa.wa.gov.au). The referral form outlines the project details and likely environmental impacts, management and consultation commitments. Typically the referral form is appended and references a detailed DEIA.

3.1.2 Level of assessment The referral is advertised by the EPA and subject to a 7-day public comment period. The EPA then determines a level of assessment based on a review of the referral and any public comments received. Historically, the EPA has typically decided not to formally assess the DoT's maintenance dredging projects and determined the projects to be 'Not Assessed—Public Advice Given'. There are three levels of formal assessment that the EPA can set: Assessment on Proponent Information Level A – for projects in which impacts can be readily

managed Assessment on Proponent Information Level B – for projects in which the impacts are

considered to be unacceptable Public Environmental Review – typically for large-scale complex projects with potential to

impact a number of environmental factors and/or with high level of public concern. The EPA is required to give written notice within 28 calendar days of its assessment level decision. However, if the EPA determines that the referral does not contain adequate information upon which to base a decision, it may request that this information is provided, and the EPA's assessment level decision will not begin until all information is received. It is therefore very important to ensure that sufficient detail is included in the referral to facilitate the EPA's determination of the level of assessment and avoid delays.

http://www.epa.wa.gov.au/


3.2 Waterways Conservation Act 1976 Dredging projects that occur within DoW's jurisdiction (Waterway Management Areas) require a Licence to Dredge under the Waterways Conservation Act 1976. The DoT maintenance dredging sites within, or in close proximity to, Waterway Management Areas include (Figure 3.1): Mandurah Entrance Channel Sticks Channel Dawesville Entrance Channel Point Grey Channel Emu Point Boat Harbour (Albany). Dredging at these sites shall require the preparation of an ‘Application for a Licence to Carry Out Dredging and/or Reclamation’ which is submitted to the DoW and is typically supported with a DEIA. For dredging sites within or in proximity to Catchment Management Areas (e.g. Port Geographe Channel, Figure 3.1) consultation with DoW and the relevant Catchment Management Authority should be completed.


Figure ‎3.1 Maintenance dredging sites and defined Waterway Management Areas and

Catchment Management Areas


3.3 Conservation and Land Management Act 1984 Projects that are likely to impact on a Marine Park should be submitted to the DPaW and the MPRA under the Conservation and Land Management Act 1984. Ten of the DoT maintenance dredging sites are within, or in close proximity to a Marine Park (Table 3.1, Figure 3.2). Maintenance dredging works at these sites may require referral if there is a possibility for the works to affect a Marine Park.

Table ‎3.1 Maintenance dredging sites within or adjacent to Marine Parks

Site Marine Park

Exmouth Boat Harbour Approximately 12 km south of the Ningaloo Marine Park

Coral Bay Maritime Facility Within the Ningaloo Marine Park

Teggs Channel (Carnarvon) Approximately 3 km north of the Shark Bay Marine Park

Denham Maritime Facility Within an exclusion zone of the Shark Bay Marine Park

Green Head Maritime Facility Approximately 1 km north of the Jurien Bay Marine Park

Jurien Bay Boat Harbour Within an exclusion zone of the Jurien Bay Marine Park

Cervantes Maritime Facility Within the Jurien Bay Marine Park

Ocean Reef Boat Harbour Within an exclusion zone of the Marmion Marine Park

Hillarys Boat Harbour Within an exclusion zone of the Marmion Marine Park

Port Geographe Channel Within an exclusion zone of the Ngari Capes Marine Park

http://pearl:8181/display/MAI/Exmouth+Boat+Harbour

http://pearl:8181/display/MAI/Carnarvon+%28Teggs+Channel%29

http://pearl:8181/display/MAI/Denham

http://pearl:8181/display/MAI/Jurien

http://pearl:8181/display/MAI/Ocean+Reef


Figure ‎3.2 Maintenance dredging sites with potential to affect Marine Parks


3.4 Contaminated Sites Act 2003 The disposal of dredged material to land has the potential to create a contaminated site. The identification, management and remediation of contaminated sites are covered by the WA Contaminated Sites Act 2003 (CS Act). The Contaminated Sites Guidelines document 'Assessment and management of contaminated Sites' (DER 2014) provides guidance on the assessment and management of contaminated sites under the CS Act (Section 4.2). Land disposal of dredged material is not dealt with specifically in the guidelines, but falls under the CS Act in that land is created, and potential human and environmental impacts must be subject to a risk assessment. This involves the comparison of sediment contaminant concentrations against the levels in the National Environment Protection (Assessment of Site Contamination) Measures guidelines (NEPC 2013) as referenced in the Contaminated Sites Guidelines (Section 4.2, DER 2014).

3.5 Aboriginal Heritage Act 1972 Dredging activities has the potential to disturb sites of Aboriginal Heritage significance. The Department for Aboriginal Affairs (DAA) maintain a register of over 22 000 Aboriginal Heritage sites (which can include artefacts, engravings, paintings, mythological or ceremonial places) in WA which have been defined under the Aboriginal Heritage Act 1972 (AH Act). If evidence of Aboriginal Heritage is located during the assessment or implementation of a project, it must be reported to the Registrar of Aboriginal Sites under the AH Act. Furthermore, where a project might impact upon an Aboriginal site, an Aboriginal Heritage survey should be commissioned, addressing anthropological and archaeological matters in the proximal area. If disturbance to an Aboriginal Heritage site is unavoidable an application for consent to the disturbance must be submitted via a notice under Section 18 of the AH Act. To assess whether an Aboriginal site is likely to be impacted during a maintenance dredging project the following information is reviewed: the Aboriginal Heritage Inquiry System (DAA 2013) to determine if there are there any

registered Aboriginal sites within the vicinity of the works. The DAA may also be queried to confirm that there are no known Aboriginal Heritage sites in the dredging and disposal areas

the nature and previous usage of the dredging site. Maintenance dredging is considered less likely to impact an Aboriginal Heritage site than capital dredging as the site has already been disturbed

the dredging design and dredging method is considered. There is a greater risk of disturbing an Aboriginal site if the dredging methods involve land-based excavation works in previously undisturbed area.

A heritage survey shall be done if assessment of the above information suggests that the level of risk is not low.


3.6 Environment Protection (Sea Dumping) Act 1981 The disposal of dredged material to sea2 requires a Sea Dumping Permit from the Australian Department of the Environment (DoE) (Figure 2.1). Applications for a Sea Dumping Permit for ocean disposal of dredged material are assessed under the Environment Protection (Sea

Dumping) Act 1981. Through this Act, the Australian Government assesses proposals to load and dump wastes and other materials at sea, permits acceptable activities and sets conditions of approval to mitigate and manage environmental impacts. To apply for a Sea Dumping Permit it is necessary to characterise the sediment prior to disposal. To ensure that the sediment sampling is appropriate, it is required to prepare and submit a Sediment Sampling and Analysis Plan (SAP) to the DoE for their approval prior to sampling (Figure 3.3). The National Assessment Guidelines for Dredging (NAGD; CA 2009) provide specific guidance for the preparation of SAPs. The DoE shall review the SAP and either approve or request amendments within ~20 working days. Following approval of the SAP, sediment sampling is completed and the results shall be submitted to the DoE in a SAP Implementation Report (Figure 3.3). Once the SAP Implementation Report has been endorsed by the DoE, a sea dumping permit application may be submitted to the DoE and should include the: approved SAP endorsed SAP Implementation Report DEIA completed Sea Dumping Permit application form. An application fee is required to be paid within 30 days after the submission of the permit application and the DoE shall review the application within 90 days of receipt of the application fee. However, if additional information is required the 90 days starts from the day the additional information is received by the DoE. It is therefore very important to ensure that sufficient information is provided initially to enable comprehensive scoping of the potential environmental issues and other appropriate information (outlined in the NAGD; CA 2009) to avoid delays.

2 The Environment Protection (Sea Dumping) Act 1981 applies in all Australian waters except for: a) when disposal is in Internal

Waters; or b) when the dredge pipeline is laid on land before discharging to Australian waters.


Figure ‎3.3 Environmental assessment for ocean disposal


3.7 Environment Protection and Biodiversity Conservation Act 1999 If a maintenance dredging project is likely to have a significant impact on matters of national environmental significance it will also require assessment under the Environment Protection and

Biodiversity Conservation Act 1999 (EPBC Act) (Figure 2.1). Environmental matters of national significance are defined by the EPBC Act as: listed threatened species and ecological communities migratory species protected under international agreements Ramsar wetlands of international importance the Commonwealth marine environment the Great Barrier Reef Marine Park World Heritage properties National Heritage places nuclear actions. Where there is the potential (or uncertainty) that a proposal may significantly impact upon any of these matters, a referral to DoE (or to the WA EPA under the assessment bilateral agreement) is required for a determination whether the proposal constitutes a ‘controlled action’ necessitating assessment and approval under the EPBC Act. DoE shall decide if the proposal requires formal assessment within ~20 business days of receipt.


4. Environmental Guidelines A number of environmental guidelines apply to the management and assessment of maintenance dredging works. Different guidelines may apply depending on the proposed dredging and disposal methods. The NAGD (CA 2009) were prepared to cover ocean disposal of sediments, but provide a useful reference for the assessment of all dredging projects (regardless of whether the works involve land disposal or ocean disposal). Where dredging is proposed in an estuarine environment the Acid Sulfate Soils Guidelines (DER 2015) should be considered. Where disposal to land (above the low water mark) is considered then the Contaminated Sites Guidelines (DER 2014) are applicable. If dredged material is planned to be disposed to landfill or if there is the potential for leachate to reach groundwater or surface water, the Landfill Waste Classification Guidelines need to be considered (DEC 2009). When sediment pore water is potentially contaminated or where dredge return water may be discharged back to the marine environment, the ANZECC & ARMCANZ (2000) Water Quality Guidelines should be considered. Details on these relevant guidelines are outlined below.

4.1 National Assessment Guidelines for Dredging The NAGD (CA 2009) provide a framework for the review and assessment of ocean disposal of dredged material in support of the federal EPBC Act and is also applicable to the EP (Sea Dumping) Act. The guidelines include information on: evaluating alternatives to ocean disposal assessing sediment quality assessing dredging and disposal sites assessing potential impacts on the marine environment and other users determining management and monitoring requirements. These guidelines were specifically prepared to inform assessment of dredging projects and sea dumping under the EPBC Act, however they do provide a useful reference even if ocean disposal of the dredged material is not intended. The various phases for assessment of dredged material for ocean disposal are outlined in Figure 4.1. The initial sediment screening phases (Phase I–II; Figure 4.1) are described in detail in Section 4.1.1, and further analyses (Phases III–V; Figure 4.1) are described in Section 4.1.2.


Source: CA (2009).

Figure ‎4.1 Assessment pathway for ocean disposal

4.1.1 Initial sediment screening (Phases I–II) The NAGD state that where there are no alternatives to ocean disposal, assessment of sediment quality is required and includes reviewing existing sediment quality information for the site. If existing data were collected from the site within five years, and the contamination status is not likely to have changed, further testing may not be required.


Where sufficient data are not available, sampling and analysis of the material to be dredged is required. The NAGD sets out guidelines for the sampling and analysis of sediments. The 95% upper confidence limit (UCL) of the sediment contaminant concentrations are compared against set Screening Levels that are used for initial assessment of the sediment (Table 4.1). The Screening Levels are presently the same as the Interim Sediment Quality Guidelines – Low values (ISQG-Low) from ANZECC & ARMCANZ (2000) (Table 4.1). In the event that the initial sediment screening identifies contaminants above the NAGD Screening Levels, the concentrations of these contaminants shall be compared against concentrations found in the ambient sediments at the proposed ocean disposal site.

Table ‎4.1 Screening Levels for sediment analytes from the National Assessment Guidelines for Dredging

Analytical parameter Screening Level (ISQG-Low value)

Metals & metalloids1 (mg/kg)

Antimony 2

Arsenic 20

Cadmium 1.5

Chromium 80

Copper 65

Lead 50

Mercury 0.15

Nickel 21

Silver 1.0

Zinc 200

Organics2 (μg/kg)

Total PCBs 23

DDD 2

DDE 2.2

Total DDT 1.6

Dieldrin 280

Chlordane 0.53

Lindane 0.323

Endrin 10

Total polycyclic aromatic hydrocarbons (PAHs) 10 000

Total petroleum hydrocarbons (TPHs) 550 mg/kg

Tributyltin (as Sn) 9 μg Sn/kg

RADIONUCLIDES4 (sum of gross alpha and gross beta) 35 Bq/g

Notes: 1. For other metals, compare to ambient baseline levels for sediments of comparable grain size in the vicinity of the

disposal site (if available) 2. Normalised to 1% total organic carbon (TOC) 3. These Screening Levels are often below the typical laboratory limit of reporting (LoR). In these instances the

results for these analytes should be reported as either ‘detected’ or ‘not detected’ 4. Maximum (Bq/g is becquerels per gram) 5. ISQG = Interim Sediment Quality Guideline, PCB = polychlorinated biphenyls,

DDD = dichlorodiphenyldichloroethane, DDE = dichlorodiphenyldichloroethylene, DDT = dichlorodiphenyltrichloroethane

Source: CA (2009)


4.1.2 Further analysis (Phases III–V) If the concentrations in the sediments to be dredged are greater than at the disposal site, the guidelines recommend further testing to assess the suitability of the dredged material for unconfined ocean disposal. The assessment framework for Phases III–V (Figure 4.1) is outlined below.

Phase III assessment – Elutriate and bioavailability testing If the Screening Levels are exceeded then further analysis of the sediment should be completed via elutriate and bioavailability testing for the exceeding analytes. Elutriate testing uses a dilution ratio of 1:4 (NAGD; CA 2009, p. 40). The elutriate results are compared against the ANZECC & ARMCANZ (2000) trigger values for Marine Water (Section 4.4). If the elutriate concentrations are below the relevant ANZECC & ARMCANZ (2000) trigger values after initial dilution (after 4 hours), then the material is considered suitable for ocean disposal (pending results of bioavailability testing). However, if the elutriate concentration is above the ANZECC & ARMCANZ (2000) trigger value, more detailed modelling of the expected dilution after ocean disposal (potentially using site specific hydrodynamic data from the disposal area) may be required. If modelling shows insufficient dilution after 4 hours (i.e. elutriate concentrations are still above the trigger values) the sediment is deemed unsuitable for ocean disposal unless effective controls can be put in place (Figure 4.1). Bioavailability testing (e.g. dilute acid extraction of metals, pore water concentrations, elutriate data) assesses the potential for sediment contaminants to impact organisms (Figure 4.1). The bioavailable concentration (95% UCL) shall be compared to the relevant criteria and if below, the material is considered suitable for ocean disposal. If the criteria are exceeded, toxicity and/or biaccumulation testing may then be implemented (see below).

Phase IV assessment – Toxicity/bioaccumulation testing If elutriate concentrations of contaminants are below the ANZECC & ARMCANZ (2000) trigger values, but the bioavailable fractions are above relevant criteria, toxicity and/or bioaccumulation testing is required. However, small dredging campaigns (less than 15 000 m3) can be exempt from toxicity testing where bioavailable contaminants exceed the Screening Level, but are below the SQG-High Value (CA 2009, Table 4.1). If a contaminant is found to be bioavailable, a desktop study of the bioaccumulation potential shall be done for those contaminants. If a contaminant is identified as bioavailable and has a potential to bioaccumulate, a bioaccumulation study may be completed. The bioaccumulation tests can be difficult to perform on some analytes, and it is permitted to skip these tests and do toxicity testing instead (CA 2009). The types of toxicity tests available vary between laboratories, and the types of tests needed vary between tropical and temperate ecosystems. The NAGD provides guidelines on how to choose the appropriate tests which should be done in consultation with the relevant local regulatory authority (e.g. DoE).

Phase V assessment A Phase V 'weight-of-evidence' assessment shall only be necessary if testing from the previous Phases I–IV is inconclusive. This assessment would review all relevant data, including field results/ecology, chemistry (bioavailability and desorption), laboratory ecotoxicity and bioaccumulation, to assist determination of the suitability for ocean disposal (CA 2009).

4.2 Contaminated Sites Guidelines The Contaminated Sites Guidelines (DER 2014) provide guidance on the assessment and management of contaminated sites under the CS Act (Section 3.4). While land disposal of


dredged material is not dealt with specifically in the guidelines, this still falls under the CS Act in that the land created may result in potential human and environmental impacts that must be subject to a risk assessment. This involves a preliminary disposal site investigation, and then the material to be dredged needs to be characterised and assessed to determine its compatibility with the receiving environment and associated land uses on a site-specific basis (DER 2014). The assessment involves the comparison of dredged sediment contaminant concentrations against investigation levels and screening levels from the National Environment Protection (Assessment of Site Contamination) Measure guidelines (NEPC 2013) as referenced in DER (2014). The investigation or screening level is the concentration of a contaminant above which further appropriate investigation and evaluation shall be required (DER 2014).

4.2.1 Ecological investigation levels and ecological screening levels The ecological investigation levels (EILs) and ecological screening levels (ESLs) provide an initial screening assessment to determine whether there is a potential risk to the environment (Table 4.2, Table 4.3). There are EILs published in Schedule B5C of NEPC (2013) for arsenic, chromium III, copper, dichlorodiphenyltrichloroethane (DDT), lead, naphthalene, nickel and zinc. The maximum and the 95% UCL of the arithmetic mean are to be used for comparison against the EILs and ESLs. If the EILs or ESLs are exceeded, a further, site-specific, risk-based investigation shall be required to determine whether contaminants levels are likely to pose an actual risk (DER 2014). These investigations may include comparison with background concentrations and/or consideration of environmental factors at the study site which may affect contaminant availability. Guidance on the nature of these investigations is provided in DER (2014).

Table ‎4.2 Contaminated Sites Guidelines ecological investigation levels for onshore disposal

Ecological investigation levels (mg/kg)

Area of ecological

significance1 Urban residential/public

open space2 Commercial/industrial3

Metals/metalloids

Arsenic 20 50 80

Chromium III 25–50 75–160 120–270

Copper 15–60 30–120 45-200

Lead 110 270 440

Nickel 1–25 10–170 20–350

Zinc 7–130 25–500 45–800

Polycyclic aromatic hydrocarbons

Naphthalene 10 170 370

Organochlorine pesticides

p,p'-DDT4 3 180 630 Notes: 1. Area of ecological significance = 99% standard protection level 2. Urban residential/public open space = 80% standard protection level 3. Commercial/industrial = 60% standard protection level 4. DDT = dichlorodiphenyltrichloroethane. Guideline is for total DDT which consists of p,p’-DDT and o,p’-DDT but

o,p’-DDT is far less common than p,p’-DDT and generally found only when p,p’ concentrations are high (NMI pers. comm. Jan 2015)

Source: NEPC (2013)


Table ‎4.3 Contaminated Sites Guidelines ecological screening levels for onshore disposal

Ecological screening levels (mg/kg dry weight) Area of ecological

significance1 Urban residential/public

open space2 Commercial/industrial3

Total recoverable hydrocarbons

C6-C10 less BTEX4 coarse/fine

125 180 215

>C10-C16 less naphthalene coarse/fine

25 120 170

>C16-C34 coarse – 300 1700

>C16-C34 fine – 1300 2500

>C34-C40 coarse – 2800 3300

>C34-C40 fine – 5600 6600

Monocyclic aromatic hydrocarbons

Benzene (coarse) 10 50 75

Benzene (fine) 10 65 95

Toluene (coarse) 10 85 135

Toluene (fine) 65 105 135

Ethylbenzene (coarse) 1.5 7 165

Ethylbenzene (fine) 40 125 185

Xylene (coarse) 10 105 180

Xylene (fine) 1.6 45 95


Benzo(a)pyrene 0.7 0.7 0.7 Notes: 1. Area of ecological significance = 99% standard protection level 2. Urban residential/public open space = 80% standard protection level 3. Commercial/industrial = 60% standard protection level 4. BTEX = Benzene, toluene, ethylbenzene, xylene Source: NEPC (2013)

4.2.2 Health investigation levels Contaminated soils disposed to land can pose a risk to human health through direct exposure (such as ingestion and inhalation) or indirect exposure (such as through groundwater contamination). The appropriate health investigation level (HIL) will depend on the future usage of the disposal site (Table 4.4): residential with garden/accessible soil (exposure level A) residential with minimal opportunities for soil access (exposure level B) public open space such as parks, playgrounds, and playing fields (exposure level C) commercial/industrial (exposure level D). The arithmetic mean of the sample concentrations should be compared against the relevant HIL. The standard deviation of the sample concentrations should be less than 50% of the HIL and no single concentration should be greater than 250% of the HIL (NEPC 2013). Where the HIL is exceeded and the criteria above not met, further risk-based investigations shall be required to determine whether modified, site specific, assessment levels can be developed.


Table ‎4.4 Contaminated Sites Guidelines health investigation levels for onshore disposal

Analytical parameter HIL "A" HIL "B" HIL "C" HIL "D" Metals & metalloids (mg/kg) Arsenic 100 500 300 3000 Beryllium 60 90 90 500 Boron 4500 40 000 20 000 300 000 Cadmium 20 150 90 900 Chromium VI 100 500 300 3600 Cobalt 100 600 300 4000 Copper 6000 30 000 17 000 240 000 Lead 300 1200 600 1500 Manganese 3800 14 000 19 000 60 000 Mercury (methyl) 10 30 13 180 Mercury (inorganic) 40 120 80 730 Nickel 400 1200 1200 6000 Selenium 200 1400 700 10 000 Organics (mg/kg) Total PAHs (16 PAHs) 300 400 300 4000 Carcinogenic PAHs 3 4 3 40 Total PCBs 1 1 1 7 Organochlorine and organophosphorus pesticides HCB 10 15 10 80 Heptachlor 6 10 10 50 Chlordane (trans- + cis- + oxy-) 50 90 70 530 Aldrin + dieldrin 6 10 10 45 DDT+DDD+DDE 240 600 400 3600 Endrin 10 20 20 100 Endosulfan (alpha- + beta- + -sulfate) 270 400 340 2000 Methoxychlor 300 500 400 2500 Mirex 10 20 20 100 Toxaphene 20 30 30 160 Atrazine 320 470 400 2500 Bifenthrin 600 840 730 4500 Chlorpyrifos 160 340 250 2000 Inorganics (mg/kg) Cyanides (free) 250 300 240 1500 Herbicides 2,4,5-T 600 900 800 5000 2,4-D 900 1600 1300 9000 MCPA 600 900 800 5000 MCBP 600 900 800 5000 Mecoprop 600 900 800 5000 Picloram 4500 6600 5700 35 000

Notes: 1. Not all of the health investigations levels (HILs) are listed as they are often not relevant to the Department of

Transport's maintenance dredging sites 2. HIL = health investigation level, PAH = polycyclic aromatic hydrocarbon, PCB = polychlorinated biphenyls,

HCB = hexachlorobenzene, DDT = dichlorodiphenyltrichloroethane, DDD = dichlorodiphenyldichloroethane, DDE = dichlorodiphenyldichloroethylene, MCPA = 2-methyl-4-chlorophenoxyacetic acid, MCBP = 4-(4-chloro-o-tolyloxy) butyric acid.

Source: NEPC (2013)


4.3 Acid Sulfate Soils Guidelines If dredging is occurring in an estuarine environment then there may be environmental risks associated with acid sulfate soils (ASS). The disturbance of ASS can increase pH levels and acidity, and cause mobilisation of metals into the water column. The Acid Sulfate Soils Guidelines Series (DER 2015) contains guidance on how to identify ASS risk areas and subsequent assessment methods including sampling and reporting for material intended for land reclamation purposes. These guidelines outline a risk assessment approach for ASS under the CS Act. Sampling for ASS should be completed as described in DER (2015) and submitted to the laboratory for chromium reducible sulfur suite analysis. The chromium reducible sulfur suite method measures the reduced inorganic sulfur content (%S) of the sediment which is then compared against Texture-based Action Criteria (DER 2015, Table 4.5). If the Action Criteria are exceeded, the laboratories complete acid base accounting (ABA) which assesses both the potential of a soil material to produce acidity from sulfide oxidation and also its ability to neutralise any acid formed (Ahern et al. 2004). If the total net acidity determined by ABA indicates sediments with positive net acidity, potential management measures will need to be considered to prevent the generation of actual ASS.

Table ‎4.5 Texture-based acid sulfate soil Action Criteria

Type of material Action Criteria

<1000 tonnes of materials is disturbed

>1000 tonnes of materials is disturbed

Texture range Approx.

clay content (%)

Equivalent sulfur (%S)

(oven-dry basis)

Equivalent acidity

(mol H+/tonne) (oven-dry basis)

Equivalent sulfur (%S)

(oven-dry basis)

Equivalent acidity

(mol H+/tonne) (oven-dry basis)

Coarse texture sands to loamy sands

<5 0.03 18 0.03 18

Medium texture sandy loams to light clays

5–40 0.06 36 0.03 18

Fine texture medium to heavy clays and silty clays

>40 0.1 62 0.03 18

Source: DER (2015) with texture range based on McDonald et al. (1990)

4.4 Australian and New Zealand Guidelines for Fresh and Marine Water Quality

Dredging causes the release of sediment pore water into the water column and return water from disposal sites is often discharged back into the marine environment. The impact of these discharges may be reviewed by comparing the water quality parameters (of elutriate sample concentrations of the proposed material prior to dredging and/or of the return water concentrations during dredging) with the ANZECC & ARMCANZ (2000) trigger values for physical and chemical stressors (Table 4.6) and toxicants (Table 4.7). The ANZECC & ARMCANZ (2000) Guidelines for Fresh and Marine Water Quality include values for a range of analytes to assess adverse effects on the marine environment. Default low-risk water quality guideline trigger values are presented for tropical (north of Carnarvon) and south-west Australia (south of Carnarvon). These trigger values are applicable to coastal lagoons (excluding estuaries) and embayments and waters less than 20 m depth.


The trigger values are for ‘chemical contaminants that have the potential to exert toxic effects at concentrations that might be encountered in the environment’ (ANZECC & ARMCANZ 2000). Trigger values for toxicants are defined for different levels of protection (Table 4.7) that signify the percentage of species expected to be protected within the ecosystem. The 99% or 95% protection level is most commonly applied in ‘slightly-moderately’ disturbed ecosystems, which would generally classify most of the DoT's maintenance dredging sites. However, some facilities would be considered highly disturbed ecosystems. Therefore the application of the guidelines should be assessed on a case-by-case basis. The mean of the water sample concentrations should be compared to the trigger values.

Table ‎4.6 Default trigger values for marine water physical and chemical stressors in tropical and south-west Australia for slightly disturbed ecosystems

Ecosystem type Chl-a TP FRP TN NOx NH4

+ DO (%)1 pH

Units μg/L Lower limit

Upper limit

Lower limit

Upper limit

Tropical Australia

Estuaries2 2 20 5 250 30 15 80 120 7.0 8.5

Marine inshore

0.7–1.43

15 5 100 2–83 1–103 90 n/a 8.0 8.4

Marine offshore

0.5–0.93 10 2–53 100 1–43 1–63 90 n/a 8.2 8.2

South-west Australia

Estuaries 3 30 5 750 45 40 90 110 7.5 8.5

Marine inshore 0.7 204 54 230 5 5 90 n/a 8.0 8.4

Marine offshore

0.34 204 5 230 5 5 90 n/a 8.2 8.2

Notes: 1. Dissolved oxygen (DO) trigger values derived from daytime measurements; DO concentrations may vary diurnally

and with depth 2. Derived trigger values do not include any data from tropical Western Australian estuaries therefore values should

be applied with caution 3. The lower values are typical of clear coral-dominated waters, while higher values are typical of turbid macrotidal

systems 4. These trigger values represent summer (low rainfall) conditions; the following values are appropriate for winter:

Chl-a (1.0 μgL-1), TP (40 μg P L-1), FRP (10 μg P L-1) 5. Not all of the trigger values for stressors and toxicants are listed in Table 4.4 as they are often not relevant to the

Department of Transport's maintenance dredging sites 6. n/a = not applicable, Chl-a = chlorophyll-a, TP = total phosphorus, FRP = filterable reactive phosphorus, TN = total

nitrogen, NOx = nitrate and nitrite, NH4+ = ammonium, DO = dissolved oxygen

Source: ANZECC & ARMCANZ (2000)


Table ‎4.7 Trigger values for toxicants in marine water at alternative levels of species protection

Toxicant

Trigger values for marine water (µg/L)1,2

Level of protection (% species)

99% 95% 90% 80% Metals & metalloids

Cadmium2,3 0.7 5.54 144 36

Chromium (Cr III)2 7.7 27.4 48.6 90.6

Chromium (Cr VI) 0.14 4.4 204 854

Cobalt 0.005 1 14 1504

Copper2 0.3 1.3 34 8

Lead2 2.2 4.4 6.64 124

Mercury (inorganic)3 0.1 0.44 0.74 1.44

Nickel2 7 704 200 560

Silver 0.8 1.4 1.8 2.64

Tributyltin (as μg/L Sn) 0.0004 0.0064 0.024 0.054

Vanadium 50 100 160 280

Zinc2 7 154 234 434

Non-metallic inorganics

Ammonia5 500 910 1200 1700

Aromatic hydrocarbons

Benzene4 500 700 900 1300


Naphthalene4 50 70 90 120 Notes: 1. Values in grey shading are typically applied to slightly-moderately disturbed systems (ANZECC &

ARMCANZ 2000) 2. The values have been calculated using a hardness of 30 mg/L CaCO3. These should be adjusted to the site

specific hardness (see Section 3.4.3 of ANZECC & ARMCANZ 2000) 3. For these toxicants, the potential for bioaccumulation and secondary poisoning effects should also be considered

(see Sections 8.3.3.4 and 8.3.5.7 of ANZECC & ARMCANZ 2000) 4. Trigger value may not protect key target species from chronic toxicity (see Section 8.3.7 of ANZECC & ARMCANZ

2000 for more information) 5. Ammonia expressed as total ammonia [NH3-N] at pH 8 6. Trigger values for other contaminants are available but are not listed here as they are not considered relevant to

the Department of Transport's maintenance dredging sites Source: ANZECC & ARMCANZ (2000)

4.5 Landfill Waste Classifications and Definitions If dredged material is planned to be disposed to a licensed or registered landfill site and there is the potential for leachate to reach groundwater or surface water, the Landfill Waste Classification and Waste Definitions (DEC 2009) need to be considered. This document provides a classification of landfill and waste types, and also criteria for the classification of wastes for acceptance to landfills licensed or registered in Western Australia under Part V of the EP Act (DEC 2009). If the material cannot be classified, sediment sampling will be required. The number of sediment samples depends on the volume to be disposed (Table 4.8). The sampling and the costs of disposal of non-inert material to classified landfill sites can be quite expensive and this should be considered in the planning phase of the maintenance dredging program (along with other sediment sampling programs to characterise dredged material; Section 4.1.1).


Table ‎4.8 Minimum number of sampling locations to support landfill waste classification

Volume (m3) Number of sampling locations

100 to 200 4

200 to 500 6

500 to 1000 8

1000 to 2000 11

2000 to 3000 15

3000 to 4000 18

4000 to 5000 20

5000 to 10 000 24

>10 000 24 (plus 4 for each additional 10 000 m3) Source: DEC (2009)

The first assessment phase involves testing for total contaminant values (Table 4.9). If any contaminant exceeds the maximum Class IV contaminant threshold values, the second assessment phase should determine the Australian Standard Leaching Procedures (ASLP) leachate concentrations and compare values to the concentration limits (CL; Table 4.10).

During the first assessment phase, the sediment samples should be analysed for all the contaminants of concern and these levels compared with the maximum contaminant threshold values and assigned a classification (Class I, II, III or IV; Table 4.9). The waste is then classified according to the highest class assigned for any of the analysed contaminants and may then be disposed to an appropriate landfill site.

Table ‎4.9 Contaminant thresholds (for total concentration) for landfill wastes

Contaminant CT1 (mg/kg) Class I

CT2 (mg/kg) Class II

CT3 (mg/kg) Class III

CT4 (mg/kg) Class IV

Metals

Arsenic 14 14 140 1400

Beryllium 2 2 20 200

Cadmium 0.4 0.4 4 40

Chromium VI 10 10 100 1000

Lead 2 2 20 200

Mercury 0.2 0.2 2 20

Molybdenum 10 10 100 1000

Nickel 4 4 40 400

Selenium 2 2 20 200

Silver 20 20 200 2000

Non-chlorinated organics

Benzene 0.2 0.2 2 20

Cresols (total) 400 400 4000 40 000

2,4-D (dichlorophenoxyacetic acid) 0.02 0.02 0.2 2

Ethylbenzene 60 60 600 6000

Petroleum hydrocarbons – – – –

Phenol (total, non-halogenated) 28.8 28.8 288 2880

Polycyclic aromatic hydrocarbons (total) – – – –

Styrene (vinyl benzene) 6 6 60 600

Toluene 160 160 1600 16 000

Xylenes (total) 120 120 1200 12 000


Contaminant CT1 (mg/kg) Class I

CT2 (mg/kg) Class II

CT3 (mg/kg) Class III

CT4 (mg/kg) Class IV

Chlorinated organics

Organochlorine pesticides, polychlorinated biphenyls etc. – – – –

Other metals2 % by weight

Aluminium , barium, boron, cobalt, copper, manganese, vanadium and zinc 5 5 10 20

Notes: 1. '–' means no contaminant threshold applicable, refer to values in Table 4.10 2. For waste containing significant quantities of these metals, preference should be given to recovery and recycling

rather than disposal 3. Not all of the contaminants are listed in Table 4.9 as they are often not relevant to the Department of Transport's

maintenance dredging sites Source: DEC (2009)

During the second assessment phase, the leachate concentrations should be compared against both the leachable concentration and the concentration limit values for the relevant waste classification (Table 4.10). The waste should then be classified according to the highest class assigned to any contaminant (Class I, II, III or IV) and disposed to an appropriate landfill site. If the leachable concentrations exceed the Class IV values then the material will need to be treated until the ASLP values are met (Table 4.10).

Table ‎4.10 Australian Standard Leaching Procedures (ASLP) leachable concentration and the concentration limit (CL) values for waste classification

Contaminant1 ASLP1 Class I

CL1 Class I

ASLP2 Class II

CL2 Class II

ASLP3 Class III

CL3 Class III

ASLP4 Class IV

CL4 Class IV

Units mg/L mg/kg mg/L mg/kg mg/L mg/kg mg/L mg/kg Metals

Arsenic 0.5 500 0.5 500 5 5000 50 20 000

Beryllium 0.1 100 0.1 100 1 1000 10 4000

Cadmium 0.1 100 0.1 100 1 1000 10 4000

Chromium VI 0.5 500 0.5 500 5 5000 50 2000

Lead 0.1 1500 0.1 1500 1 15 000 10 60 000

Mercury 0.01 75 0.01 75 0.1 750 1 3000

Molybdenum 0.5 1000 0.5 1000 5 10 000 50 40 000

Nickel 0.2 3000 0.2 3000 2 30 000 20 120 000

Selenium 0.5 50 0.5 50 5 500 50 2000

Silver 1 180 1 180 10 1800 100 7200

Aluminium, barium, boron, cobalt, copper, manganese, vanadium and zinc

– 5% by weight

5% by weight

– 10% by weight

– 20% by weight

Non-chlorinated organics

Benzene 0.01 18 0.01 18 0.1 180 1 720

Cresols (total) 20 7200 20 7200 200 72 000 2000 288 000

Ethylbenzene 3 1080 3 1080 30 10 800 300 n/a

C6-C9 petroleum hydrocarbons (PH)

– 2800 – 2800 – 28 000 – 112 000

C16-C35 PHs – 450 – 450 – 4500 – 18 000


Contaminant1 ASLP1 Class I

CL1 Class I

ASLP2 Class II

CL2 Class II

ASLP3 Class III

CL3 Class III

ASLP4 Class IV

CL4 Class IV

Units mg/L mg/kg mg/L mg/kg mg/L mg/kg mg/L mg/kg

(aromatics)

C10->C35 PHs (aliphatics) – 28 000 – 28 000 – 280 000 – –

Phenols (total, non-chlorinated) 1.44 42 500 1.44 42 500 14.4 425 000 144 –

PAHs (total) – 100 – 100 – 1000 – 4000

Benzo(a)pyrene 0.0001 5 0.0001 5 0.001 50 0.01 200

Styrene 0.3 108 0.3 108 3 1080 30 4320

Toluene 8 518 8 518 80 5180 800 –

Xylenes (total) 6 1800 6 1800 60 18 000 600 –

Chlorinated organics

2,4-D 0.3 360 0.3 360 3 1440 30 5760

OCP scheduled wastes

– 50 – 50 – 50 – 50

Other solvents – 50 – 50 – 500 – 2000

PCBs – 50 – 50 – 50 – 50 Notes: 1. Not all of the contaminants are listed in Table 4.8 as they are often not relevant to the Department of Transport's

maintenance dredging sites 2. ALSP = Australian Standard Leaching Procedures; CL = concentration limit, PH = petroleum hydrocarbons,

PAHs = polcyclic aromatic hydrocarbons, D = dichlorophenoxyacetic acid, OCP = organochlorine pesticides, PCBs = polychlorinated biphenyls

Source: DEC (2009)

4.6 Sediment nutrient guidelines No guidelines have been defined for nutrients in marine sediment in Western Australia and further research is required before nutrient guidelines can be developed (ANZECC & ARMCANZ 2000). Nutrient analyses shall instead be compared against available background concentrations.


5. Environmental Impacts and Management The DoT’s statewide maintenance dredging program includes sites with a wide range of climatic, oceanographic, biogeographic and social conditions. This diversity requires careful consideration of the relevant environmental factors to ensure appropriate environmental impact pathways are considered and that the monitoring and management for each maintenance dredging campaign is effective to address the relevant environmental objectives. This is described in detail in the following sections.

5.1 Environmental factors and objectives An environmental factor is part of the environment that may be impacted by an aspect of the proposal (EPA 2013a). The environmental objective for each factor is the desired goal that, if met, will indicate that the proposal is not expected to have a significant impact on the environment (EPA 2013a). The EPA’s environmental factors and associated environmental objectives underpin the EIA process in Western Australia and are described in EAG8 (EPA 2013a; Table 5.1). The EPA uses these factors and objectives (which are grouped into themes) as a basis for assessing whether a proposal's impact on the environment is acceptable (Section 3.1). The most relevant environmental factors for the DoT's maintenance dredging works are likely to be: benthic communities and habitats coastal processes marine environmental quality marine fauna flora and vegetation terrestrial environmental quality hydrological processes inland waters environmental quality amenity heritage.

Table ‎5.1 Environmental factors and objectives used by the Environmental Protection Authority for assessing a proposal's impact on the environment

Theme Environmental factor Environmental objective

Sea

Benthic communities and habitat To maintain the structure, function, diversity, distribution and viability of benthic communities and habitats at local and regional scales.

Coastal processes To maintain the morphology of the subtidal, intertidal and supratidal zones and the local geophysical processes that shape them.

Marine environmental quality To maintain the quality of water, sediment and biota so that the environmental values, both ecological and social, are protected.

Marine fauna To maintain the diversity, geographic distribution and viability of fauna at the species and population levels.

Land

Flora and vegetation To maintain representation, diversity, viability and ecological function at the species, population and community level.

Landforms To maintain the variety, integrity, ecological functions and environmental values of landforms and soils.

Subterranean fauna To maintain representation, diversity, viability and ecological function at the species, population and assemblage level.

Terrestrial environmental quality To maintain the quality of land and soils so that the


Theme Environmental factor Environmental objective

environment values, both ecological and social, are protected.

Terrestrial fauna To maintain representation, diversity, viability and ecological function at the species, population and assemblage level.

Water

Hydrological processes To maintain the hydrological regimes of groundwater and surface water so that existing and potential uses, including ecosystem maintenance, are protected.

Inland waters environmental quality To maintain the quality of groundwater and surface water, sediment and biota so that the environmental values, both ecological and social, are protected.

Air Air quality To maintain air quality for the protection of the environment and human health and amenity.

People

Amenity To ensure that impacts to amenity are reduced as low as reasonably practicable.

Heritage To ensure that historical and cultural associations are not adversely affected.

Human health To ensure that human health is not adversely affected.

Integrating factors

Offsets To counterbalance any significant residual environmental impacts or uncertainty through the application of offsets.

Rehabilitation and closure

To ensure that premises are closed, decommissioned and rehabilitated in an ecologically sustainable manner, consistent with agreed outcomes and land uses, and without unacceptable liability to the State.

Source: EPA (2013a)

5.2 Significance framework The EPA's significance framework for assessing environmental impact, as outlined in EAG9 (EPA 2013b), aims to understand the likely 'significance' (similar to 'consequence' in a traditional risk assessment terminology) of the environmental impacts of a proposal. The EPA's significance framework relates to the extent to which a project is likely to meet the EPA's environmental objectives (Figure 5.1; EPA 2013a). The EPA significance framework is applied as per the following (see also Section 3.1): if the EPA considers that a proposal can meet all of its environmental objectives then the

proposal is considered unlikely to have a significant impact on the environment if the EPA considers that a proposal may not meet one or more of the EPA’s environmental

objectives its impact on the environment is considered likely to be significant. Subsequently, key environmental factors are identified when the EPA's environmental objectives may be met, but there is the need for further information or conditions related to proposal implementation

if the EPA considers that a proposal is unlikely to meet one or more of its environmental objectives then its effect on the environment is likely to be unacceptable.

Through this approach it is intended that the environmental impact assessment shall focus on the impacts to each environmental factor that are most likely to be significant (EPA 2013a). The EPA's significance framework should be applied throughout the EIA process for DoT's maintenance dredging operations. In addition, a traditional risk assessment framework has been adopted (Section 5.3) to identify the potential key environmental factors as described in EPA (2013a).


Source: EPA (2013b)

Figure ‎5.1 Environmental Protection Authority's significance framework for the environmental impact assessment process

5.3 Environmental impacts of maintenance dredging operations The DoT’s maintenance dredging projects typically involve removal of relatively small volumes of clean marine sands from navigation channels adjacent to existing facilities. Nonetheless, a number of biophysical and social impacts may arise during a maintenance dredging project (Table 5.2). DoT maintenance dredging projects would usually fall into the "acceptable" zone of the EPA's significance framework. However to provide further resolution of the potential environmental issues, presented herein is a review of recent DoT maintenance dredging projects that determines the range of potential impacts, their consequence (Table 5.3) and likelihood (Table 5.4), to determine a risk level (Table 5.5) for a "typical" maintenance dredging campaign. The lists in these tables are not exhaustive and other appropriate management measures may be available at specific sites. Management measures shall be outlined in campaign-specific DEMPs. The highest risks, for a typical maintenance dredging campaign, are likely to be associated with turbidity and sedimentation, and mobilisation of contaminants.


Table ‎5.2 Potential impacts associated with the Department of Transport's maintenance dredging operations

Environmental factor(s) Issue Potential impacts Biophysical

Benthic communities and habitat Marine environmental quality

Turbidity and sedimentation Light limitation to benthic flora Smothering of benthic habitat Abrasion of marine organisms

Benthic communities and habitat Marine environmental quality Terrestrial environmental quality

Mobilisation of contaminants Deteriorating water quality Contamination of marine

organisms


Nutrient release from sediment Nuisance algal growth

Benthic communities and habitat Marine environmental quality Terrestrial environmental quality Inland waters environmental

quality

Acid sulfate soils

Acidification of waters Deoxygenation of the water

column Release of heavy metals

Coastal processes Landforms

Sediment removal/alteration of local topography

Downdrift erosion Updrift accretion


Hydrocarbon spill Contamination of marine organisms

Marine fauna Noise Disturbance of marine/terrestrial fauna

Marine fauna Vessel movement Collision with marine fauna

Benthic communities and habitat Marine environmental quality

Introduced marine pest species Introduction of invasive marine

pest species into previously un-impacted sites

Social

Amenity Turbid plume Reduced aesthetics and recreational values

Amenity Unsightly disposal site Reduced aesthetics

Human health Exposure to contaminants in dredged material

Reduced health of local community

Amenity Restricted public access to dredging and/or disposal sites

Restricted commercial and/or recreational values

Air quality Amenity Human health

Odour Reduced aesthetics and health of local community

Amenity Human health

Noise Reduced aesthetics and health of local community


Dust Reduced aesthetics and health of local community


5.4 Environmental management The DoT implements a number of management measures to reduce the potential impacts of maintenance dredging operations, including: initial consideration of the timing, scale, methods and potential impacts of the maintenance

dredging project (including review of any previous close-out reports) determining the status of environmental approvals for maintenance dredging at the site design of the dredging project to minimise environmental impacts at both the dredging and

disposal site liaison with affected stakeholders preparation (or update) of a DEIA and submission to regulatory authorities if required preparation (or update) of a DEMP in consultation with the dredging contractor to ensure

effective monitoring and management of the works on site communication with the dredging contractor to ensure environmental commitments are

understood and included in the PEP regular supervision of site works collection and review of environmental monitoring data obtained during dredging works communication of monitoring results to relevant parties post-dredging monitoring maintaining a complaints register completion of close-out report to document project and inform future campaigns. The potential biophysical and social impacts from maintenance dredging can generally be reduced to a low risk through the implementation of management measures. The greatest potential environmental risk is likely to be associated with turbidity and release of contaminants and nutrients.


Table ‎5.3 Description of consequences

Value Description Natural environment Human environment Marine fauna (individuals)

1 Insignificant Negligible impact with no remediation required No alteration to ecosystems

Very minor disruption to small section of community Insignificant impacts on quality of life No community interest/concern

Behaviour, physiology, and well-being barely or weakly affected

2 Minor Minor impacts with minimal remediation required Minor alteration to ecosystems Recovery period of weeks to months

Isolated short-term disruption to some communities Minor impacts on quality of life Limited community interest/concern Possible isolated local and individual concerns

Behaviour, physiology, and well-being affected to a degree that minimally influences individual reproductive success

3 Moderate Moderate impacts with some remediation required Moderate alteration to ecosystems Recovery period of months to years

Small number of minor illnesses Significant disruption to some communities Significant short-term or minor long-term impact on quality of life Moderate community interest/concern, limited (if any) regional or state interest

Behaviour, physiology, and well-being affected to a degree that individual reproductive success is reduced

4 Major Major impacts with considerable remediation required Major alteration to ecosystems Recovery period of years to decades

Small number of illnesses or loss of life Significant, widespread disruption to communities Significant long-term impact on quality of life Widespread community interest/concern – regional and state interest

Behaviour, physiology, and well-being substantially affected with reduction in individual reproductive success

5 Catastrophic Catastrophic impacts with significant remediation required Irreversible alteration to ecosystems Long-term environmental recovery period of decades

Large number of illnesses or loss of life Severe and widespread disruption to communities Severe long-term impacts on quality of life State, national and potential international interest/concern

Behaviour, physiology, and well-being severely (or mortally) affected with individual reproductive success greatly reduced or ceased

Table ‎5.4 Descriptions of likelihoods

Value Descriptor Description

1 Rare Occurs only in exceptional circumstances

2 Unlikely Could occur but not expected

3 Possible Should occur at some time

4 Likely Will probably occur in most circumstances

5 Almost certain Is expected to occur in most circumstances

Table ‎5.5 Risk matrix

Likelihood

Rare Unlikely Possible Likely Almost certain

Consequence

Insignificant 1 2 3 4 5

Minor 2 4 6 8 10

Moderate 3 6 9 12 15

Major 4 8 12 16 20

Catastrophic 5 10 15 20 25

Risk severity Low (1–4) Medium (5–10) High (11–25)


Table ‎5.6 Risk assessment of key biophysical and social issues that may be associated with the Department of Transport's maintenance dredging operations

Environmental factors Issue Potential impacts Likelihood Consequence Inherent risk rating Possible management measures1 Likelihood Consequence Residual

risk rating Biophysical



Turbidity and sedimentation Light limitation to benthic flora Smothering of benthic habitat Abrasion of marine organisms

4 3 12

Select appropriate dredge plant Review dredging method Time dredging to specific environmental conditions (e.g. winter

and onshore winds) Construct containment bunds, weirs, overflow systems, spreader

plates, submarine discharge

3 2 6



Terrestrial environmental quality

Nutrient release from sediment Nuisance algal growth 3 2 6

Select appropriate dredge plant Dispose to land instead of sea Time dredging to specific environmental conditions (e.g. winter

and onshore winds)

2 2 4




Mobilisation of contaminants Deteriorating water quality Contamination of marine

organisms 3 4 12

Dispose to land instead of sea Containment at disposal site Select appropriate dredge plant

2 4 8




Inland waters environmental quality

Acid sulfate soils

Acidification of waters Deoxygenation of the water

column Release of heavy metals

2 4 8 Minimise oxidation during dredging and at disposal site Dispose to sea instead of land Contain fine fraction

1 3 3

Coastal processes Landforms

Sediment removal/alteration of local topography

Downdrift erosion Updrift accretion

3 2 6 Discharge material back into sediment cell (i.e. sand bypassing) 3 1 3




Hydrocarbon spill Contamination of marine organisms

3 3 9 Inspect dredge daily Review oil spill and refuelling procedures Audit spill response and clean-up procedures

2 2 4

Marine fauna Noise Disturbance of marine/terrestrial fauna

2 2 4

Select appropriate dredge plant Selection of disposal site Time dredging to non-migratory periods Time dredging to avoid migratory periods for marine mammals

2 1 3

Marine fauna Vessel movement Collision with marine fauna 2 4 8 Time dredging to avoid migratory periods for marine mammals 1 4 4



Introduced marine pest species

Introduction of invasive marine pest species into previously un-impacted sites

2 3 6

Weekly clean of dredge using fresh water and brush the sides of the hull to minimise growth

Clean dredge and pipes at the end of a campaign and ensure remaining water and sediment is flushed out when loading vessel onto the trailer for transport

Transport dredge via road between maintenance dredging sites

1 3 4

Social

Amenity Turbid plume Reduced aesthetics and recreational values

4 2 8

Select appropriate dredge plant Time dredging to specific environmental conditions (e.g. winter) Public education, including signage/public notices and

community liaison

4 1 4

Amenity Unsightly disposal site Reduced aesthetics 3 2 6 Rehabilitation of site upon completion of disposal Modify disposal method

2 1 3


Environmental factors Issue Potential impacts Likelihood Consequence Inherent risk rating Possible management measures1 Likelihood Consequence Residual

risk rating

Human health Exposure to contaminants in dredged material

Reduced health of local community

2 3 6

Selection of disposal site Capping of disposal site on completion Restrict public access to disposal site Dredging without overflow

1 3 3

Amenity Restricted public access to dredging and/or disposal sites

Restricted commercial and/or recreational values

4 2 8

Selection of disposal site Public education, including signage/public notices and

community liaison Provide alternate access to areas

3 1 3


Odour Reduced aesthetics and health of local community

3 2 6 Time dredging to specific environmental conditions Limit proximity of public to dredging operation

2 2 4

Amenity Human health

Noise Reduced aesthetics and health of local community

3 2 6 Time dredging to specific environmental conditions Implement noise emission control measures (e.g. silencers)

2 2 4


Dust Reduced aesthetics and health of local community

2 2 4 Time dredging to specific environmental conditions Implement dust emission control measures (e.g. silt fences)

1 2 3

Note: 1. This list is not exhaustive and other appropriate management measures may be available at specific sites. Management measures shall be outlined in campaign-specific Dredging Environmental Management Plans


6. Environmental Monitoring of Dredging Operations Environmental monitoring may be completed before, during and after a dredging campaign to quantify the biophysical and social impacts and to help ensure that any impacts are minimised. Environmental monitoring prior to dredging is typically done to characterise the material to be dredged, and determine background water quality conditions and benthic habitats at the dredging and disposal site (where applicable). Environmental monitoring is completed during and after the dredging campaign to document any environmental impacts from the works. Environmental issues associated with turbidity and release of contaminants and nutrients are the focus of the environmental monitoring for the DoT's maintenance dredging program (Section 5.3). The environmental monitoring for a dredging campaign should be informed by an understanding of the: dredged material (volume and characteristics), dredging method, location (of dredging and disposal sites), and duration and timing of the dredging works. Comprehensive environmental monitoring is often not warranted for small-scale projects of short duration (e.g. <2 weeks) and involve small volumes (e.g. <1500 m3). The monitoring recommended herein is considered appropriate for the small-scale maintenance dredging done by the DoT and/or by leasees within DoT facilities. Detailed methods for monitoring are presented below for pre-dredging (Section 6.1) and during dredging (Section 6.2). Post-dredging monitoring is generally only required if there are significant environmental issues associated with the works and shall be dependent on the findings of the EIA process (e.g. TBT monitoring at Beadon Creek).

6.1 Pre-dredging sampling Pre-dredging monitoring typically involves sediment sampling of the proposed dredged material (and soil sampling at the disposal site if relevant) and may include benthic habitat surveys. The procedures for determining the pre-dredging monitoring requirements are presented in (Figure 6.1). Sediment sampling is completed to characterise the environmental and engineering characteristics of the dredged material in the dredging area. Soil sampling is required to determine the existing contaminant status of the onshore disposal site. The dredged material for the DoT maintenance dredging campaigns is typically marine sand, and occasionally the dredged material may be predominantly detached seagrass/algal material, known as wrack. The need for pre-dredging benthic habitat surveys shall be assessed on a case-by-case basis and only completed when sensitive benthic habitats in the vicinity of the dredging area may be impacted by smothering or light reduction (Figure 6.1).


Figure ‎6.1 Decision tree for monitoring prior to dredging

6.2 During-dredging monitoring A range of environmental monitoring is often completed during dredging to ensure the environmental impacts of maintenance dredging works are documented and understood. Monitoring components could include site photographs, plume sketches, remote imagery, aerial photography and water quality monitoring (Figure 6.2). The relevant procedures for each of the monitoring components are provided in the sections below and should be included in the individual DEMPs. These monitoring procedures should be discussed with the dredging contractor during the preparation of the DEMP to ensure that the monitoring commitments are feasible, well understood, and that the required monitoring equipment is available. Environmental monitoring data should be provided by the dredging contractor to the Principal weekly. This (together with other relevant information) is tracked using environmental monitoring checklists that accompany the weekly progress reports (Section 2.6, Section 6.3).


Note: 1. The dredged material is considered to be clean if all contaminants are below the relevant guidelines (Section 4)

Figure ‎6.2 Decision-tree for monitoring during dredging

6.3 Reporting All environmental monitoring data collected during dredging should be reviewed weekly to assess whether there is any possibility of environmental or socio-economic impacts from the dredging campaign. Weekly environmental monitoring checklists should be completed by the environmental consultant and provided to the engineering consultants for inclusion in the weekly progress reports to the Principal. The dredging contractor should also provide daily logs and weekly reports for inclusion in these progress reports. The environmental data from a dredging campaign shall be analysed and interpreted in the close-out report on completion of dredging (Section 2.6). A plume coverage figure shall be included in the close-out report along with a discussion on the proximity of the plume to nearby sensitive benthic habitats (if applicable).


6.4 Monitoring summary A summary of the pre-dredging and during dredging monitoring commitments that may be required to be implemented by the Principal and the dredging contractor during the dredging campaign is provided in Table 6.1.

Table ‎6.1 Environmental monitoring summary table

Monitoring Frequency Responsibility

Pre-dredging

Sediment sampling Every five years1 Principal

Wrack sampling Every five years1 Principal

Sediment sampling for engineering purposes Prior to or during each campaign Principal

Benthic habitat survey Prior to campaign where deemed necessary Principal

During dredging

Plume sketches Daily during dredging Contractor

Remote imagery Before, during and after dredging Principal

Site photographs Daily during dredging Contractor

Aerial photography At least once per campaign Principal

Water quality monitoring Dependent on length of dredging (approximately once every three weeks) Principal

Note: 1. Unless contamination of the site is likely to have increased or new pollution sources are present (CA 2009). For

sites that are infrequently dredged (i.e. greater than five years) sediment samples shall be obtained prior to each campaign


7. Review and Audits The EMF is intended to be a ‘live’ document, which is able to undergo regular revision to ensure best practice methods continue to be applied as knowledge, technology and requirements change. This is possible because the EMF document is available on the online extranet system, Pearl, which allows it to be quickly edited and updated by designated authors, and personnel working on the program can be efficiently notified of any changes. Any recommended changes to the EMF shall be captured as part of the ongoing monthly meetings (attended by the Principal, engineering consultant, environmental consultant and dredging contractor), and the close-out report of each dredging campaign. These changes can be quickly incorporated into the online version of the EMF, which in turn can be downloaded as a pdf document. Any changes made to the online version of the EMF document are documented in Pearl as they may be used for audit purposes. An annual internal audit of the maintenance dredging program and the EMF (carried out by the environmental consultant) shall ensure that all environmental commitments have been met during the 12-month audit period, and clearly identify any pending environmental commitments. The audit shall be carried out in Pearl against the current online version of the EMF and the EMF pages will be locked against editing during the audit. Any non-conformances can then be investigated in the context of the documented changes to the EMF made in the previous year (see above). The audit shall be efficient and transparent as all of the lines of evidence required for the audit are expected to be available on Pearl and therefore easily checked and linked into the audit report. The audit report shall discuss any non-conformances and the EMF may then be reviewed to address any issues in consultation with the Principal, engineering consultant and the dredging contractor.


8. References Ahern CR, McElnea AE, Sullivan LA (2004) Acid Sulfate Soils Laboratory Methods Guidelines.

Queensland Department of Natural Resources Mines and Energy, Indooroopilly, Queensland, June 2004

ANZECC, ARMCANZ (2000) Australian and New Zealand Guidelines for Fresh and Marine Water Quality, Prepared by Australian and New Zealand Environment and Conservation Council, Agriculture and Resource Management Council of Australia and New Zealand, Canberra, Australian Capital Territory, October 2000

CA (2009) National Assessment Guidelines for Dredging. Commonwealth of Australia, Canberra, Australian Capital Territory

DAA (2013) Aboriginal Heritage Inquiry System. Available from <http://www.dia.wa.gov.au/AHIS/> [Accessed 6 October 2014]

DEC (2009) Landfill Waste Classification and Waste Definitions 1996 (As amended December 2009). Prepared by the Department of Environment and Conservation, Perth, Western Australia, December 2009

DER (2014) Assessment and Management of Contaminated Sites – Contaminated Sites Guidelines. Prepared by the Department of Environment Regulation, Perth, Western Australia, December 2014

DER (2015) Identification and Investigation of Acid Sulfate Soils and Acidic Landscapes: Acid Sulfate Soils Guideline Series. Prepared by the Department of Environment Regulation, Perth, Western Australia, June 2015

DSEWPaC (2011) Stockholm Convention on Persistent Organic Pollutants (POPs). Available from http://www.environment.gov.au/settlements/chemicals/international/index.html [Accessed 26 June 2013]

EPA (2009) Environmental Assessment Guidelines No. 3 for Protection of Benthic Primary Producer Habitat in Western Australia's Marine Environment (EAG3). Prepared by the Environmental Protection Authority, Perth, Western Australia, December 2009

EPA (2011) Environmental Assessment Guidelines No. 7 for Marine Dredging Proposals (EAG7). Prepared by the Environmental Protection Authority, Perth, Western Australia, September 2011

EPA (2012) Environmental Impact Assessment (Part IV divisions 1 and 2) – Administrative Procedures 2012. Western Australian Government Gazette, 223 (Special):5937–5959

EPA (2013a) Environmental Assessment Guidelines No. 8 for Environmental Factors and Objectives. Prepared by the Environmental Protection Authority, Perth, Western Australia, June 2013

EPA (2013b) Environmental Assessment Guidelines No. 9 for Application of a Significance Framework in the Environmental Impact Assessment Process (EAG9). Prepared by the Environmental Protection Authority, Perth, Western Australia, June 2013

EPA (2015a) Environmental Assessment Guidelines No. 14 for Protecting the Quality of Western Australia's Marine Environment (EAG15). Prepared by the Environmental Protection Authority, Perth, Western Australia, March 2015

EPA (2015b) Environmental Assessment Guidelines No. 15 for Preparation of Management Plans under Part IV of the Environmental Protection Act 1986 (EAG17). Prepared by the Environmental Protection Authority, Perth, Western Australia, August 2015


McDonald RC, Isbell RF, Speight JG, Walker J Hopkins MS (1990) Australian Soil and Land Survey Field Handbook, A 1 (2nd edition). CSIRO Publishing

NEPC (2013) National Environment Protection (Assessment of Site Contamination) Measure Amendment 2013 (No. 1), National Environment Protection Council, Schedule 2013

BMT Oceanica Pty Ltd PO Box 462 Wembley

WA 6913 Australia Tel: +61 8 6272 0000

Fax: +61 8 6272 0099 [email protected]

www.bmtoceanica.com.au

Appendix C

OEPA correspondence regarding suitability of the DoT's Environmental Management Framework (8 October 2014)

Government of Western Australia Office of the Environmental Protection Authority

Mr James Holder Manager Maritime Projects - Coastal Infrastructure 0urRef: ST07-2°13-°007

, , , -r . Enquiries: Paul Zahra, 6145 0823 Department of Transport _ 0 . _ 1 ^ Email: [email protected] 1 Essex Street FREMANTLE WA 0160

Dear Mr Holder

MINISTERIAL STATEMENT 391 - PORT GEOGRAPHE - ENVIRONMENTAL MANAGEMENT FRAMEWORK

Thank you for your email of 6 October 2014 regarding environmental management at the Port Geographe Development. The Office of the Environmental Protection Authority (OEPA) accepts that the existing proponent, Tallwood Nominees Pty Ltd, is no longer involved in the active management of coastal processes.

It is acknowledged that the Minister for Transport, through the Department of Transport, has now taken full responsibility for the coastal management following significant reconfiguration of the coastal structures. Prior to the release of a new Ministerial Statement requiring a specific environmental management plan, the OEPA accepts that the Department of Transport's Environmental Management Framework (September 2012) would be appropriate to manage any further coastal activities in the interim, until such time as the new environmental management plan is approved.

The OEPA recommends that any variation to existing coastal management activities be appropriately communicated with the community prior to commencement.

Should you have any queries in relation to this correspondence, please contact Paul Zahra on 6145 0823.

Yours sincerely

Ian Munro MANAGER COMPLIANCE BRANCH

October 2014

The Atrium Level 8, 168 St Georges Terrace, Perth, Western Australia 6000. Postal Address: Locked Bag 10, East Perth, Western Australia 6892.

Telephone: (08)6145 0800. Facsimile: (08) 6145 0845. Website: www.epa.wa.gov.au

Appendix D

Example plume sketch and Secchi depth templates

Secchi Depth Measurements Sampler:

Date:

Time:

Cloud Cover (%)

Site Coordinate System Longitude (E) Latitude (S) Time Secchi Depth (m)

Disk Hitting Seafloor?

1 ddd°mm.mmm'/ ddd°mm'ss.ss"/

UTM-Easting-Northing

Yes / No



Yes / No



Yes / No



Yes / No


UTM-Easting-Northing Yes / No

Comments:

BMT Oceanica Pty Ltd PO Box 462 Wembley

WA 6913 Australia Tel: +61 8 6272 0000

Fax: +61 8 6272 0099 [email protected]

www.bmtoceanica.com.au

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