site management planmarch 2016 site management plan lot 9005 allott way maddington wa prepared for...

MARCH 2016

SITE MANAGEMENT PLAN Lot 9005 Allott Way Maddington WA

Prepared for Hughes Family Trust Ref. W15038_01 I Revision 1

Document ID W15038_01 Rev 1.docx ii Revision: 1 Revision Date: 31/03/2016

REVISION HISTORY AND DISTRIBUTION LIST

Revision No. Issue Date Status Delivered

No. of Copies

0 26/10/2015 Initial submission for Auditor comment Stephen Hughes Hughes Family Trust Charlie Barber Australian Environmental Auditors

1 electronic copy

1 31/03/2016 Re-submission addressing Auditor comments

1 electronic copy

APPROVALS

Name Signature Title Date

Author Jeff Shivak Principal Environmental Scientist 31/03/2016

Checked Jeff Shivak Principal Environmental Scientist 31/03/2016

Approved Jeff Shivak Principal Environmental Scientist 31/03/2016

Document ID W15038_01 Rev 1.docx iii Revision: 1 Revision Date: 31/03/2016

EXECUTIVE SUMMARY

Enpoint has been engaged by the Hughes Family Trust (HFT) to prepare a Site Management Plan (SMP) to facilitate the clearance of environmental condition number 9 contained within the Western Australian Planning Commission (WAPC) conditional approval to subdivide Lot 9005 Allott Way, Maddington. This SMP applies to provisional Lots 521, 522 and 523, which collectively comprise an area of approximately 3.1 hectares.

HFT wish to sell the Site as-is and in order to realise the full value of the Site and to attract potential buyers, they require the Site to be re-classified under Contaminated Sites Act 2003 (the Act) and subsequently WAPC Condition 9 cleared. As such, the final Site layout and/or subdivision are currently not known. Therefore, this SMP has been designed taking this into consideration and provides mechanisms for ensuring that all gas protection measures required to be incorporated into any building designs are implemented during the planning phase, reviewed and approved by the appropriate authorities prior to any construction taking place.

The objective of this SMP is to provide details on how contamination identified during previous investigations at the Site will be managed in order to facilitate the clearance of WAPC Condition 9.

The scope of work is to take the findings of the prior investigations into account and to prepare a SMP in line with the DER’s guideline for ‘Assessment and management of contaminated sites’ (DER, 2014).

The management measures required to facilitate the development of the Site are summarised below.

Pre-Development / Planning Stage:

Communication of the risks outlined in this document via the following:

o Disclosure under the Act in the prescribed form (Form 6). o Community engagement.

Restrict unmitigated access to soil and abstraction of groundwater via relevant Contaminated Sites Act 2003 administrative measures (e.g. Site classification and notice on the land titles).

Development of design specifications for any proposed buildings at the Site incorporating the appropriate gas membrane specifications and submission for review and approval by the Auditor and/or DER/DoH prior to commencement of any construction at the Site.

Construction Phase:

Preparation of a Construction Environmental Management Plan detailing the environmental constraints and safety requirements during construction.

Baseline groundwater and landfill gas monitoring prior to commencement of construction.

Survey of groundwater bores within 500m down-gradient of the Site.

Decommissioning of all monitoring wells within the footprint of any ground disturbing works or any construction works to ensure they do not become vertical conduits for landfill gas migration.

Capture of all stormwater within a network of sealed drains and discharge to the local off-Site stormwater drainage system (no soak wells to be installed on-Site).

Ongoing groundwater and landfill gas monitoring throughout the duration of construction works.

Preparation of a Construction Quality Assurance Plan for the installation of the nominated gas protection measures.

Integration of the approved gas protection measures with the Site development and construction works

Document ID W15038_01 Rev 1.docx iv Revision: 1 Revision Date: 31/03/2016

Post Development:

Same management measures as during the Construction Phase but only triggered when any post development ground disturbing activities are required (e.g. maintenance of underground services and/or upgrades/additions to the Site are proposed).

Biannual groundwater monitoring and quarterly landfill gas monitoring to be completed for one (1) year post-development.

Maintenance and inspection of gas protection measures, infrastructure, equipment and monitoring network on a quarterly basis or until a risk assessment can demonstrate that this is no longer required.

Provided the management measures and contingency measures prescribed in this SMP are adhered to, the Site is considered suitable for a typical industrial/ commercial development.

This SMP has been designed to facilitate the re-classification of the Site and subsequently clearance of WAPC Condition 9 in order for a potential sale of the Site to proceed. Given that a buyer for the Site has not yet been identified, it is not possible / plausible to include any future proposed building designs and layouts within the SMP until the Site is sold and the new owner have drafted their own building designs and layout. As such, once the final Site layout and subdivision have been decided, any building design drawings must be drafted to include Site specific gas mitigation measures. The building design plans incorporating the gas protection measures along with the Construction Quality Assurance Plan for implementing these measures must be submitted to the DER/DoH and/or the Auditor for review and approval prior to any construction commencing at the Site.

On the basis of the above, Enpoint recommends that the Site be reclassified as ‘contaminated – restricted use’, with the restriction being that the management measures outlined in this SMP are implemented in full.

Document ID W15038_01 Rev 1.docx v Revision: 1 Revision Date: 31/03/2016

CONTENTS

EXECUTIVE SUMMARY .............................................................................................................. III

1. INTRODUCTION ................................................................................................................... 1 1.1 Background .................................................................................................................... 1 1.2 Approach ........................................................................................................................ 2 1.3 Objective and Scope of Work......................................................................................... 2 1.4 Site Identification ............................................................................................................ 3 1.5 Site Classification and Planning Conditions ................................................................... 4

2. PREVIOUS INVESTIGATIONS ............................................................................................. 5 2.1 Landfilling Extent ............................................................................................................ 5 2.2 Summary ........................................................................................................................ 5 2.3 Investigation Outcomes .................................................................................................. 6

3. CONCEPTUAL SITE MODEL ............................................................................................... 7 3.1 Sources .......................................................................................................................... 7

3.1.1 Primary Sources .................................................................................................. 7 3.1.2 Secondary Sources and Affected Media ............................................................. 7

3.2 Exposure Pathways ....................................................................................................... 8 3.3 Receptor Identification ................................................................................................... 8 3.4 Exposure Assessment ................................................................................................... 8

4. RISK ASSESSMENT OUTCOMES ..................................................................................... 10

5. REMEDIATION OBJECTIVES ............................................................................................ 14 5.1 Rationale for Selection of Gas Protection Measures ................................................... 14 5.2 Typical Gas Protection Measures ................................................................................ 16

5.2.1 Site Specific Design ........................................................................................... 17 5.3 Construction Quality Assurance ................................................................................... 18 5.4 Review and Approval of Gas Protection Measures ..................................................... 18

6. COMMUNITY ENGAGEMENT ............................................................................................ 19 6.1 Stakeholder Involvement .............................................................................................. 20 6.2 Future Site Owners and Occupiers .............................................................................. 20

7. SITE MANAGEMENT PLAN ............................................................................................... 21 7.1 Timeframe for Site Management ................................................................................. 21 7.2 Management Measures ............................................................................................... 21

7.2.1 Pre-Development / Planning Stage ................................................................... 22 7.2.2 Construction Phase ........................................................................................... 23 7.2.3 Post Development.............................................................................................. 27

7.3 Contingency Measures ................................................................................................ 28 7.4 Summary of Reporting Requirements .......................................................................... 31 7.5 Assumptions ................................................................................................................. 33 7.6 Uncertainties ................................................................................................................ 33

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8. CONCLUSIONS AND RECOMMENDATIONS ................................................................... 34 8.1 Site Suitability ............................................................................................................... 34

8.1.1 Site Specific Building Designs ........................................................................... 34 8.2 Limitations and Constraints .......................................................................................... 34 8.3 Site Re-Classification ................................................................................................... 34

9. REFERENCES .................................................................................................................... 35

10. LIMITATIONS AND IMPORTANT INFORMATION ABOUT THIS REPORT ..................... 36

ACRONYMS ................................................................................................................................ 38

TABLES IN TEXT

Table 1 Site Identification............................................................................................................ 3

Table 2 Site Classification and Planning Conditions .................................................................. 4

Table 3 Summary of Previous Investigations ............................................................................. 5

Table 4 Investigation Outcomes ................................................................................................. 6

Table 5 Primary Sources ............................................................................................................ 7

Table 6 Secondary Sources........................................................................................................ 7

Table 7 Exposure Assessment ................................................................................................... 9

Table 8 Tier 1 Risk Assessment Outcomes – Human Health .................................................. 10

Table 9 Tier 1 Risk Assessment Outcomes – Ecological ......................................................... 12

Table 10 Guidance Values for Gas Protection (per Table 7 of NSW EPA (2012)) .................... 14

Table 11 Scores for Protection Measures (per Table 8 of NSW EPA (2012)) ........................... 14

Table 12 Rationale for Selection of Gas Protection Measures ................................................... 16

Table 13 Typical Gas Protection Measures ................................................................................ 16

Table 14 Community Engagement ............................................................................................. 19

Table 15 Stakeholder Involvement ............................................................................................. 20

Table 16 Management Measures – Pre-Development / Planning Stage ................................... 22

Table 17 Management Measures – Construction Phase ........................................................... 23

Table 18 Management Measures – Post Development ............................................................. 27

Table 19 Contingency Measures ................................................................................................ 28

Table 20 Summary of Reporting Requirements ......................................................................... 31

Document ID W15038_01 Rev 1.docx vii Revision: 1 Revision Date: 31/03/2016

FIGURES AFTER TEXT

Figure 1 Site Location

Figure 2 Site Plan

Figure 3 Inferred Former Landfill Extent

Figure 4 Soil Sample and Asbestos Sample Locations

Figure 5 Groundwater Monitoring Well Locations

Figure 6 Landfill Gas Monitoring Well Locations

APPENDICES

Appendix A Western Australian Planning Commission Application

Appendix B Gas Membrane Technical Specifications

Appendix C Gas Membrane Typical Construction Details

Document ID: W15038_01 Rev 1.docx 1 Revision: 1 Revision Date: 31/03/2016

1. INTRODUCTION

Enpoint has been engaged by the Hughes Family Trust (HFT) to prepare a Site Management Plan (SMP) to facilitate the clearance of environmental condition number 9 contained within the Western Australian Planning Commission (WAPC) conditional approval to subdivide Lot 9005 Allott Way, Maddington (the Site – refer to Figure 1 for the Site location). This SMP applies to provisional Lots 521, 522 and 523, which collectively comprise an area of approximately 3.1 hectares (refer to Figure 2 for the Site plan showing the layout of the provisional Lots at the Site).

HFT wish to sell the Site as-is and in order to realise the full value of the Site and to attract potential buyers, they require the Site to be re-classified under Contaminated Sites Act 2003 (the Act) and subsequently WAPC Condition 9 cleared. As such, the final Site layout and/or subdivision are currently not known. Therefore, this SMP has been designed taking this into consideration and provides mechanisms for ensuring that all gas protection measures required to be incorporated into any building designs are implemented during the planning phase, reviewed and approved by the appropriate authorities prior to any construction taking place.

1.1 Background

Enpoint understands that an SMP has been prepared for provisional Lots 522 and 523 of the Site by WSP based on the outcomes of investigations conducted at the Site by various consultants since 2004 (WSP, 2014). The WSP (2014) SMP has been reviewed by the accredited WA Contaminated Sites Auditor (Charlie Barber, Australian Environmental Auditors) along with the various investigation reports and a Mandatory Auditor’s Report (MAR) (AEA, 2014) prepared with a recommendation that the Site be reclassified under the Contaminated Sites Act 2003 (the Act) as ‘Contaminated – restricted use’.

The MAR (AEA, 2014) along with all supporting documentation was submitted to the WA Department of Environment Regulation (DER) and Department of Health (DoH) for review and sign-off to facilitate clearance of the WAPC condition applied to these Lots. It is understood that the DER agreed with the recommendations made in the AEA (2014) MAR, but the DoH indicated that the SMP was too generic and required more specific details regarding the specifications for landfill gas mitigation design.

Since the AEA (2014) MAR for these Lots was prepared and management measures relating to landfill gas were identified to be inadequate by the DoH, further discussions with HFT have indicated that they would like to proceed with the clearing of conditions on the whole of the Site rather than the previous staged approach of clearing the conditions for Lots 522 and 523 first then progressing with the clearance of conditions for Lot 521. As such, this requires the preparation of an SMP for the whole of the Site (Lot 9005), which details the management measures required to mitigate risks relating to contamination identified on all Lots and further detail relating to landfill gas management measures required to adequately mitigate the landfill gas risk across the Site.

Investigations on Lot 521 have been conducted by Enpoint (formerly Environmental Strategies WA) and have been documented in a Detailed Site Investigation report (ESWA, 2014), which has been endorsed by the appointed Auditor.


1.2 Approach

Given the comments by the DoH on the previous SMP relating to Lots 522 and 523 (WSP, 2014) and subsequent discussions with HFT and the Auditor, it has been agreed that an SMP be developed as follows:

In a simple manner that clearly outlines the requirements which include:

o What management measures are required o How to implement the management measures o Who is responsible for implementation of the management measures o How to monitor / measure the effectiveness of the management measures during and

following development of the Site

Common management measures applicable across the whole of the Site so that the Site may be developed regardless of whether it sold as a whole or subdivided and sold separately

Inclusion of specific criteria for landfill gas mitigations measures for the subgrade and building bases that do not restrict any potential buyers of the Site to a specific building design/type.

Note that several of the management and contingency measures outlined in the WSP (2014) SMP have been nominated as measures in this SMP, given the following:

Lot 521 and Lots 522 and 523 (which make up the Site), were all part of a much larger site at one stage prior to subdivision and the Site history (and therefore contaminants of potential concern and corresponding contamination risk profile) on each of these Lots is the same.

The nominated management measures are deemed valid to adequately mitigate the identified risks.

The management measures outlined in WSP (2014) for Lots 522 and 523 have been reviewed by Charlie Barber and endorsed in the MAR (AEA, 2014).

The DER agreed with the recommendations made in the MAR (AEA, 2014)

Given the above, and the comments made by the Auditor and the DoH, this SMP incorporates further details around the following:

Timeframes and responsibilities for implementation of each of the management measures; and

Specifications for appropriate landfill gas protection measures and how they are to be incorporated and installed within any proposed building at the Site.

1.3 Objective and Scope of Work

The objective of this SMP is to provide details on how contamination identified during previous investigations at the Site will be managed in order to facilitate the clearance of WAPC Condition 9.

The scope of work is to take the findings of the prior investigations into account and to prepare a SMP in line with the DER’s guideline for ‘Assessment and management of contaminated sites’ (DER, 2014). This SMP outlines how the contamination risks identified at the Site will be effectively managed, including:

Documenting the management measures required to mitigate specific risks to the relevant receptors identified in the conceptual site models developed as part of previous investigations conducted at the Site and endorsed by the Auditor;


Outlining the timeframe for which Site management is necessary;

Detailing how Site activities are to be managed prior to and during Site development and management and monitoring requirements following Site development; and

Outlining the contingency measures that will be implemented in the event that any action criteria / trigger levels are exceeded.

This SMP can be relied upon by the Auditor in making a professional assessment of the Site, and for the purposes of submitting the MAR and recommendations to the DER. Likewise the DER can rely on this SMP in making their decision to re-classify the Site under the Act.

This SMP does not address any geotechnical issues associated with the Site and its intended development.

1.4 Site Identification The Site identification details are provided in Table 1 below.

Table 1 Site Identification

Site Details Description

Lot Number Lot 9005

Street Address 20 Allott Way

Suburb / Town Maddington WA

Certificate of Title Lot 9005 on Deposited Plan 40777 Volume: 2560 Folio: 13 (The current Certificate of Title is presented in Appendix A)

Site Location Figure 1

Site Coordinates Refer to Figure 2 for coordinates of Site boundaries

Site Area 31,314m2

Land Owner Patricia Hughes

Site Plan Figure 2

Current Land Use Vacant

Local Government Authority City of Gosnells

Current Zoning General Industrial (no proposed changes to current zoning)

Proposed Future Land Use Industrial


1.5 Site Classification and Planning Conditions Table 2 below outlines the Site classification details in accordance with the Act, WAPC conditions required to be cleared and accredited Contaminated Sites Auditor details:

Table 2 Site Classification and Planning Conditions

Aspect Details

Date Reported under the Act April 2008

Reasons for Classification Previous Site investigations identified hydrocarbons and asbestos in soil, and hydrocarbons, pesticides and heavy metals in groundwater at concentrations exceeding the relevant assessment levels at the time.

Date Site Classified under the Act 7 May 2008

Site Classification Possibly contaminated – investigation required

WAPC Application Number 152284 (WAPC Application is provided in Appendix A)

WAPC Condition to be cleared Condition 9

Contaminated Sites Auditor Details Charlie Barber – Australian Environmental Auditors


2. PREVIOUS INVESTIGATIONS

2.1 Landfilling Extent

Historical landfilling at the Site appears to have occurred within three (3) separate clay pits (Cells 1 to 3) excavated across the Site, which extend to as deep as 12m below ground level in some areas. The inferred lateral extent of the landfill is presented in Figure 3.

2.2 Summary

Investigations completed at the Site are summarised in Table 3 below.

Table 3 Summary of Previous Investigations

Lot(s) Type of Investigation Description Reference

9005 Preliminary Site Investigation (PSI)

PSI of the whole of the Site EES, 2004a

9005 Detailed Site Investigation (DSI)

DSI of the whole of the Site based on the outcomes of the PSI (EES, 2004a)

EES, 2004b

9005 Supplement to DSI Statistical analysis of soil sample results obtained from surface fill material (capping layer)

EES, 2004c

9005 Soil gas assessment

Landfill gas monitoring from existing groundwater monitoring wells installed within the waste material and from dedicated gas sampling points installed within the capping layer

EES, 2005a

9005 Groundwater monitoring

Additional groundwater sampling to confirm the direction of groundwater flow and provide additional attenuation data for discussion with respect to the risk assessment included in the DSI (EES, 2004b)

EES, 2005b

522 & 523 PSI PSI pertaining to Lots 522 and 523 only to expedite the clearance of WAPC conditions on these Lots

Douglas Partners, 2009

522 & 523 DSI DSI on this portion of the Site based on the outcomes of the PSI (Douglas Partners, 2009)

Douglas Partners, 2011

522 & 523 Additional Site Investigation (ASI)

ASI addressing data gaps identified in previous investigations in this portion of the Site (Douglas Partners, 2009 and 2011)

WSP, 2012

522 & 523 Landfill gas monitoring

Additional landfill gas monitoring to characterise the gas risk

WSP, 2013

521 DSI DSI addressing data gaps identified in previous investigations in this portion of the Site (EES, 2004a,b,c and 2005a,b)

ESWA, 2014


Sampling locations and monitoring well locations from each of the investigations conducted at the Site are presented as follows:

Soil sample and asbestos sample locations – Figure 4

Groundwater monitoring well locations – Figure 5

Landfill gas monitoring well locations – Figure 6

2.3 Investigation Outcomes

The outcomes of the environmental investigations as they relate to this SMP are outlined in Table 4 below.

Table 4 Investigation Outcomes

Media Investigation Outcomes Human Health Ecological

Asbestos

Landfill Material

Asbestos was not investigated within the landfill material Not Applicable

Capping Layer

ACM was detected at one test pit location (TP20 on Provisional Lot 522) above the DoH (2009) 0.05%w/w assessment criteria for ACM at commercial/industrial sites

Not Applicable

Soil

Landfill Material

Limited soil sampling has been completed within the landfill material Aromatic hydrocarbons were detected above the applicable human health investigation levels at the time (HILF) in two (2) locations within Cell 3

Soil sample results obtained from landfill material were not compared to any ecological investigation levels

Capping Layer

CoPCs were not detected in any samples collected from soils of the capping layer above the applicable human health investigation levels at the time (HILF)

Concentrations of the following CoPCs were detected above the applicable ecological assessment levels at the time (EILs) Metals (copper, zinc) Total recoverable hydrocarbons (TRH) Dieldrin

Groundwater

Concentrations of the following CoPCs were detected at the Site above the DoH (2014) Non-Potable Groundwater Use guideline (NPUG) or other relevant international non-potable use guidelines*: Ammonia Metals (iron, nickel, lead) Benzo(a)pyrene TRH*

Concentrations of the following CoPCs were detected at the Site above the ANZECC 2000 Fresh Water Assessment Levels (FWAL): Nitrogen Phosphorus Hydrogen sulphide Metals (arsenic, cadmium, copper, nickel,

lead, zinc, mercury)

Landfill Gas

The gas regime at the Site was characterised as being a Characteristic Situation 3 or a ‘Moderate Risk’ being typical of generation from an old landfill

Not Applicable


3. CONCEPTUAL SITE MODEL

This section summarises the sources, known and potentially affected media, transport mechanisms and linkage to potential receptors.

3.1 Sources

3.1.1 Primary Sources

The primary sources of known or potential landfill gas, soil and/or groundwater contamination at the Site are summarised in Table 5 below.

Table 5 Primary Sources

Known and Potential Primary Source(s) Comment

Waste material from landfilling

Clay extraction occurred at the Site between the mid-1940’s until sometime between 1985 and 1986 Backfilling of the Site with uncontrolled fill commenced sometime between 1986 and 1987 until the clay pits

were completely backfilled sometime between 1989 and 1991

Soil investigations from within the waste material conducted by EES (2004a and 2004b) indicates that there are concentrations of contaminants of potential concern (CoPCs) above the applicable assessment levels at the time present within the waste material

Asbestos was not assessed within the fill material

Asbestos within the capping layer

Asbestos fines (AF) and ACM were detected within the capping layer during test pitting conducted on-Site Calculations in accordance with the Department of Health (DoH, 2009) guideline indicated that the percent

asbestos in soil was below the Soil Asbestos Investigation Criteria for commercial/industrial premises, with the exception of ACM in one soil sample (collected from test pit TP20 on Lot 522), which was above the DoH (2009) commercial/industrial criteria

Capping layer material of an unknown source

The capping layer appears to have been applied across the Site between the late 1980’s and the early 1990’s Soil investigations from within the capping layer did not identify any CoPCs above the applicable human

health assessment levels at the time (HILF)

Soil investigations from within the capping layer identified concentrations of metals, TRH and dieldrin above the applicable EILs at the time

3.1.2 Secondary Sources and Affected Media

The known or potential secondary or diffuse sources of contamination remaining at the Site are summarised in Table 6 below.

Table 6 Secondary Sources

Known and Potential Secondary Source(s) Assessed Known Potential

Impacted soil within the waste material -

Landfill gas generation within the waste material -

Asbestos in the sub-surface soil matrix of the waste material -

Asbestos in surface soils - -

Impacted soil within the capping layer (upper 0.5m at Lot 521 and upper 0.3m at Lots 522 and 523) - -

Impacted soil within the capping layer beneath the depth of investigation -

Asbestos in sub-surface soils within the capping layer -* -

Note*: ACM was only detected in one sample (TP20) above the DoH (2009) assessment criteria for commercial/industrial sites.


3.2 Exposure Pathways

The following outlines the potential exposure pathways by which the CoPCs can possibly or are likely to be transferred from the primary and secondary sources of CoPCs to receptors:

Direct contact with potentially impacted soil beneath the depth of investigation resulting from Site development / construction earthworks within the capping layer

Airborne dust generation resulting from Site development / construction earthworks

Leaching of contaminants from soil to groundwater

Advective transport of impacted groundwater

Abstraction of impacted groundwater by on-Site bores

Off-Site migration of impacted groundwater originating from the Site and abstraction by off-Site bores

Vertical migration of landfill gas and accumulation in on-Site buildings / structures

Lateral migration of landfill gas and accumulation in off-Site buildings / structures

3.3 Receptor Identification

The following receptors may have the potential to be exposed to CoPCs at the Site:

Construction worker during Site development (human)

Maintenance workers following completion of development works (human)

Site occupants following completion of development works (human)

Off-Site occupants (human)

Bickley Brook (ecological)

3.4 Exposure Assessment

For a site to be deemed ‘contaminated’, and for contamination to be deemed a ‘risk’, a complete pathway must exist between the source of contamination and a receptor (e.g. people or components of an ecosystem).

Table 7 provides a pictorial representation of the known sources, routes of transport from sources to contaminated media, identified routes of exposure of receptors to media and the endpoint receptors.

Where an exposure pathway is likely to be complete then Tier 1 or screening level risk assessment is completed to assess if CoPCs in soil, groundwater and/or landfill gas have the potential to pose risk under the identified exposure scenario. Section 4 provides the risk characterisation outcomes for the exposure routes identified and provides the information to support the significance of the linkages shown in Table 7.


Table 7 Exposure Assessment


4. RISK ASSESSMENT OUTCOMES

The following tables outline the Tier 1 human health (Table 8) and ecological (Table 9) risk assessment outcomes for each of the potentially complete exposure pathways outlined in in Table 7 under each phase of development works. These risk assessment outcomes form the basis of the management measures outlined in this SMP.

Table 8 Tier 1 Risk Assessment Outcomes – Human Health

Stage of Development Works

Media Receptors Risk Assessment Outcomes Management / Protection Measures

Pre-Development Works (Current State)

Soil Site occupants

Soil within the horizon of the capping layer that was investigated (upper 0.5m on Lot 521 and upper 0.3m on Lots 522 and 523) did not contain CoPCs at concentrations greater than the HILF or asbestos in soil greater than the DoH (2009) soil asbestos investigation criteria (with the exception of one location – TP20 on Lot 522).

Impacted soil that may be present below this depth at the Site is not currently a risk to human health because the Site is currently vacant with a fence around the entire perimeter.

None

Groundwater

On-Site groundwater users

Impacted groundwater at the Site is not currently a risk to human health because the Site is currently vacant with a fence around the entire perimeter. None

Off-Site groundwater users

Impacted groundwater originating from the Site has the potential to be migrating off-Site. However, exposures to groundwater contaminants via dermal contact, ingestion or inhalation are considered to be negligible given the following:

The premises down-gradient of the Site are industrial The salinity of groundwater in this area is deemed to be unsuitable for

drinking water and irrigation as a garden bore (which was confirmed by the TDS concentrations obtained from wells at the Site)

None

Landfill Gas

Site occupants Landfill gas concentrations identified on-Site are not currently a risk to human health because the Site is currently vacant with a fence around the entire perimeter.

None

Off-Site occupants

Landfill gas has been identified at the northern perimeter (LFGW1 on Lots 521 and 522), eastern perimeter (BH19) and southwestern perimeter (BH9). Off-Site migration along the northern Site boundary has been delineated by the absence of landfill gas present in off-Site wells to the north (BH21, BH22 and BH23) and utility pits located along Allott Way to the north. The locations of BH9 and BH19 coincide with locations where Cells 1 and 3 respectively extend across the Site boundary.

The potential for landfill gas to be present on adjacent properties where landfill material is known to extend across the Site boundaries should be communicated with the landowners of these properties so that appropriate investigations may be undertaken to assess the risk that landfill gas from the waste material present beneath these properties may pose to receptors on these sites. Given that waste material extends onto these adjacent properties, any such investigation would be the responsibility of the landowners of these sites and not the responsibility of HFT.




Construction Phase

Soil Construction workers

Given that construction works at the Site would only need to be conducted on or within the capping layer (laying foundations, excavations for service trenches, etc.); it is not expected that waste material at the Site would be intersected during these works.

Therefore, any potential soil impacts present at the Site below the depth of investigation does not pose unacceptable risks to human health during the construction phase.

Preparation of a Construction Environmental Management Plan (CEMP) to ensure that the following management measures are adhered to during the construction phase:

Excavations / service trenching should be limited to: o the upper 0.5m of the capping layer on Lot 521; and o the upper 0.3m of the capping layer on Lots 522 and 523

Certified clean fill is imported to make up Site levels rather than cutting and filling

Any proposed building designs / layouts will need to take the above into consideration. Where final design levels are above the level of adjacent properties, either naturally or due to importation of clean fill, retaining walls will need to be incorporated along the property boundaries in these areas. The CEMP should include health and safety considerations (in the form of a safety management plan) during the construction phase and in addition, soil, water, waste, noise and dust management, monitoring and emergency response actions.

Groundwater Construction workers

Exposure pathways between groundwater at the Site and construction workers during Site development / construction are considered to be incomplete given the following:

Groundwater at the Site ranges from approximately 2m to 3m below ground level and excavations / service trenching are to be limited to the upper 0.5m/0.3m of the capping layer only, rendering routine, direct contact with impacted groundwater highly unlikely

Inhalation of organic vapours emanating from impacted groundwater are negligible given that volatile constituents (benzene and F1) were only present in two monitoring wells and at concentrations up to three orders of magnitude below the HSLD for sand

Any potential exposures to impacted groundwater would be reduced to negligible by the application of safe work practices.

Site works during the construction phase should be limited to the capping layer only, as detailed in the CEMP.

Landfill Gas Construction workers Landfill gas has the potential to accumulate in any service trenches / utility pits excavated during the construction phase at the Site.

Personal (exposure) and ambient air monitoring during the duration of the works to be conducted in any service trenches / utility pits, which would mitigate the risk of explosion and/or asphyxiation of construction workers by any landfill gas that may accumulate in these areas.

Post Development Soil

Site occupants

Intrusive maintenance workers

Potentially Impacted soil beneath the depth of investigation within the capping layer and beneath the capping layer has the potential to pose a risk to Site occupants and intrusive maintenance workers.

It is recommended that a Memorial be placed on the Title restricting ground disturbing activities to within the upper 0.5m on Lot 521 and 0.3m on Lots 522 and 523 of the capping layer only.

Therefore, the exposure pathway between impacted soil and human receptors on-Site under the future proposed industrial land use is considered incomplete.




Groundwater Site occupants Groundwater poses a potential risk to human health if it is abstracted for use on-Site.

It is recommended that a Memorial be placed on the Title restricting the abstraction of groundwater from the Site. Therefore, the exposure pathway between impacted groundwater and human receptors on-Site under the future proposed industrial land use is considered incomplete.

Landfill Gas Site occupants Landfill gas has the potential to accumulate within any proposed building at the Site.

Landfill gas protection measures are required to be incorporated into the construction of any proposed building(s) on-Site to mitigate the risk posed by landfill gas present at the Site. The protection measures should include at a minimum, installation of a proprietary gas resistant membrane to reasonable levels of workmanship under independent construction quality assurance (CQA) with integrity testing and independent validation. Rationale for selection of the gas protection measures is provided in Section 5.1. Landfill gas does not pose unacceptable risks to human health at the Site under the proposed industrial land use provided implementation of the above protective measures are incorporated into the construction of any building(s) proposed for the Site.

Table 9 Tier 1 Risk Assessment Outcomes – Ecological


Soil Terrestrial

ecological receptors

Flora

Soil within the upper 0.5m of Lot 521 and 0.3m of Lots 522 and 523 of the capping layer did not contain CoPCs at concentrations greater than the EIL. As such, it is considered that the soil within the capping layer will not pose unacceptable risks to ecological receptors given the following:

The Site is located in an industrial area and surrounded by industrial premises There are no ecological receptors present at the Site It is likely that the entire or majority of the Site surface will be covered by hardstand

None

Groundwater Terrestrial


Flora

Groundwater at the Site contains nutrients (nitrogen and phosphorus) and various metals at concentrations above the FWAL. It is considered that the groundwater beneath the Site will not pose unacceptable risks to ecological receptors at the Site given the following:

There are no surface water bodies present on the Site The Site is located in an industrial area and surrounded by industrial premises There are no ecological receptors present at the Site It is likely that the entire or majority of the Site surface will be covered by hardstand

None



Bickley Brook Bickley Brook is located approximately 250m down-gradient of the Site. There is the potential that groundwater impacts originating from the Site may be migrating off-Site to impact Bickley Brook.

Groundwater monitoring to be conducted to assess the following:

Groundwater flow directions If groundwater impacts originating from the former landfill Cells are

migrating off-Site at concentrations above the Fresh Water Assessment Levels

Groundwater monitoring should include LFGW5, LFGW6, LFGW7 and LFGW8 along the downgradient boundary Lot 521, which are installed outside of the landfill cells to assess if groundwater impacts are migrating outside of the landfill cells.

Landfill Gas Terrestrial


Flora

Landfill gas identified at the Site does not pose a risk to any ecological receptors given that the Site is located within an industrial area and there are no ecological receptors present at the Site. None


5. REMEDIATION OBJECTIVES

The overall objective is to make the Site suitable for a commercial/ industrial development and subsequent occupation, and therefore to ensure that all the identified contamination risks are reduced to an acceptable level via application of the suite of risk management measures listed in Section 7 of this SMP.

5.1 Rationale for Selection of Gas Protection Measures

The required gas protection measures have been adopted in accordance with Table 7 and Table 8 of NSW EPA (2012), which have been adapted for conditions in Australia from the procedures outlined in BS 8485:2007. Table 7 of NSW EPA (2012) provides ‘guidance values’ for gas protection measures required for a given Characteristic Gas Situation. These values are outlined in Table 10 below.

Table 10 Guidance Values for Gas Protection (per Table 7 of NSW EPA (2012))

Characteristic gas situation (CS)

Required gas protection guidance value

Low density residential

Medium–high density residential (strata title)

Public buildings, schools, hospitals, shopping centres

Standard commercial buildings (offices, etc.)

Large commercial (warehousing) and industrial buildings

1 0 0 0 0 0 2 3 3 3 2 1 (a)

3 4 3 3 2 2 4 6 (b) 5 (b) 5 4 3 5 6 (b) 6 (b) 6 (c) 5 4 6 6 (b) 6 (b) 6 (c) 6 6

(a) If maximum measured methane concentration exceeds 20%, increase to CS3.

(b) Residential development not recommended at CS4 and above without pathway intervention and high level of management.

(c) Consideration of evacuation issues and social risks required.

For the purposes of selecting guidance values at the Site, based on the proposed upgrade works, it fits into the category of ‘Large commercial (warehousing) and industrial buildings’.

Once a guidance value has been obtained from Table 10 above based on the outcomes of the Site specific landfill gas monitoring data to determine a Characteristic Gas Situation, gas protection measures or combinations of measures may be evaluated using the scores provided in Table 8 of NSW EPA (2012). These gas protections measures and associated scores are outlined in Table 11 below.

Table 11 Scores for Protection Measures (per Table 8 of NSW EPA (2012))

Measure or system element Score Comments

Venting and dilution measures

Passive sub-floor ventilation with very good performance (steady state concentration of methane over 100% of ventilation layer remains below 1% v/v at a wind speed of 0.3 m/s)

2.5


Measure or system element Score Comments

Passive sub-floor ventilation with good performance (steady state concentration of methane over 100% of ventilation layer remains below 1% v/v at a wind speed of 1 m/s and below 2.5% v/v at a wind speed of 0.3 m/s)

1 If passive ventilation cannot meet this requirement an active system will be required.

Subfloor ventilation with active abstraction or pressurisation

2.5 Robust management systems must be in place to ensure long-term operation and maintenance.

Ventilated car park (basement or undercroft) 4 Assumes that car park is vented to deal with exhaust fumes in accordance with BCA(a)

requirements.

Floor slabs

Reinforced concrete ground bearing floor slab 0.5 It is good practice to install ventilation in all foundation systems to effect pressure relief as a minimum. Breaches in floor slabs, such as joints, have to be effectively sealed against gas ingress to maintain these performances.

Reinforced concrete ground bearing foundation raft with limited service penetrations cast into slab

1

Reinforced concrete cast in situ or post- tensioned suspended slab with minimal service penetrations and water bars around all penetrations and at joints

1.5

Fully tanked basement 2

Membranes

Taped and sealed membrane to reasonable levels of workmanship with inspection and validation

0.5 The performance of membranes is dependent upon the design and quality of the installation, protection from and resistance to damage post installation and the integrity of joints in membranes that require joints. Materials that offer some degree of self-sealing and repair are preferred.

Proprietary gas-resistant membrane to reasonable levels of workmanship under independent construction quality assurance (CQA)

1

Proprietary gas resistant membrane to reasonable levels of workmanship under independent CQA with integrity testing and independent validation

2

Monitoring and detection (alarms)

Intermittent monitoring using hand-held equipment

0.5 Monitoring and alarm systems are only valid as part of a combined gas protection system. Where fitted, permanent systems should be installed in the underfloor venting system but can also be provided in the occupied space as a back-up.

Permanent monitoring system installed in the occupied space of the building

1

Permanent monitoring system installed in the underfloor venting / dilution system

2

Pathway intervention

Vertical barriers – Required for residential and public buildings at CS4 and above.


Table 12 below provides the rationale for selection of the gas protection measures required to be incorporated into the design of any proposed buildings at the Site.

Table 12 Rationale for Selection of Gas Protection Measures

Aspect Description Guideline Reference Report Reference

Characteristic Gas Situation

CS 3 based on GSV values as follows:

GSV of 2.693L/hr for methane based on: o maximum methane of 96.2%v/v; and o flow rate of 2.8L/hr

GSV of 0.538L/hr for carbon dioxide base on: o maximum methane of 19.2%v/v; and o flow rate of 2.8L/hr

Table 8.5 of C665, 2007 --

Gas Protection Guidance Value

2 – for ‘Large commercial (warehousing) and industrial buildings’

Table 7 of NSW EPA (2012) Table 10

Gas Protection Measure

Proprietary gas resistant membrane to reasonable levels of workmanship under independent CQA with integrity testing and independent validation

Table 8 of NSW EPA (2012) Table 11

5.2 Typical Gas Protection Measures

In accordance with the rationale for selection of the gas protections measures required at the Site as detailed above, Table 13 provides further detail / recommendations for typical gas protection measures that will need to be incorporated into any building design at the Site.

Table 13 Typical Gas Protection Measures

Aspect Typical Design Details

Gas Resistant Membrane

(Liquid Boot*)

The Liquid Boot* gas proof membrane features the following characteristics providing suitable outcomes to CS3 gas risk applicable at the Site: Liquid Boot meets the requirements of the LA methane mitigation standards Published testing proving the performance of the product in methane applications in

addition to significant worldwide construction precedence including Australia The material is spray applied and forms a single monolithic membrane without

seams. It is suitable for complex detailing including walls, lift pits, pile surfaces and

pipe/reinforcing penetrations. The product can be applied to constructions expected to be subjected to

subsidence without high risk of failure, as it is designed to suspend to the underside of slab.

Venting System Options

GeoVent* Network (Sub-slab application)

GeoVent is a 300 mm x 25 mm trenchless venting system comprised of a molded plastic cuspated core encased in a filter geotextile. The system includes conversion fittings to allow connection to conventional PVC piping typically used to connect to inlet and outlets at the building exterior. Outlets are typically terminated with a wind driven ventilator to enhance the performance of the venting system. Interleaving inlet and outlet strips are supported by a layer of gravel screenings (no fines), with nominal particle size distribution. This combination promotes efficient cross-flow ventilation over the site, allowing passive dilution of landfill gases to appropriate concentrations. Typical geocomposite and gravel networks will include: Silting geotextile layer to separate sub soil from screening material Layer of 100-300mm of 20mm (no fines) screening GeoVent strips placed 1m from building perimeter and 3-10m spacings dependent

on ventilation requirements


Aspect Typical Design Details

The use of geocomposites with gravel is often considered in LFG building design as it will generally be the most economical and efficient method of generating the required ventilation rates. Alternative options are generally considered when gravel layers exceed thicknesses of 150mm. Likewise if calculations determine excessive number of inlets/outlets, more practical options can be investigated. At this point, it is likely that thicknesses of 100-150mm will be assessed. It should be noted that this option may be considered only if structural load bearing permits.

Trench Network (Beneath hardstand areas)

Trench network designs are derived from gas or leachate collection systems in landfill applications. The method of construction limits the porous media to trenches in a similar layout to that described above. The network is often comparatively spaced with surrounding sub base material suitable for structural requirements. A typical trench network would include: Excavation (300 x 300mm) trench Placement of silting layer (as described above) Placement of geocomposite or slotted PVC pipe, generally within the centre of

trench Backfill using nominal screenings as described above, encapsulating the gravel at

the surface with the silting layer The selection of slotted PVC and geocomposite is dependent on the likelihood of venting activation. PVC will often be favoured over geocomposites given their increased aerodynamic efficiency within the system, particularly at high flow velocities. PVC: 5-20% open surface area Geocomposite: >95% open surface area

Note*: Liquid Boot and GeoVent are proprietary gas protection measures developed and manufactured by CETCO. CETCO are Australian based and possess an internal contracting division (including design and construct) for the installation of its products and also has a national network of approved applicators (including WA). Technical data on the performance of the CETCO Liquid Boot membrane and venting system designs along with typical construction details are provided in Appendix B and C respectively.

5.2.1 Site Specific Design

The design details listed in Table 13 above are typical designs only, which would be suitable to mitigate a CS3 gas risk. The development of a Site specific gas protection solution must be developed once the final Site layout and subdivision are decided and upon completion of structural and architectural planning. Gas protection measures are best considered early in the design phase to achieve both maximum performance and value engineering. As such, the above should be treated as a guide only at this Stage in establishing a Site specific solution.

Further to that detailed in Table 13 above, following are further design specifications that need to be taken into consideration:

The product must be specified such that it accommodates all Site specific construction details

The product must be installed to accommodate a staged construction format

Liquid Boot would likely need to be applied at a dry thickness of 1.5mm on T-40 base fabric (see Technical Specifications included in Appendix B and typical construction details included in Appendix C)

The Liquid Boot layer will need to be subject to thickness and smoke testing to prove the efficacy of the material (see Technical Specifications included in Appendix B)

The material will be protected by a G-1000 protective geotextile (see Technical Specifications provided in Appendix B and typical construction details included in Appendix C)


Further to the above specifics on the material, the following considerations will need to be assessed within the construction phase:

Any sub-base material must be free of foreign objects which could potentially damage the membrane. Further information will be provided on selection of appropriate subfloor ventilation

Sub-contractors / other trades will need to be isolated from the work zone during installation to prevent damage of the membrane.

Traffic must not commence until the G-1000 material is placed to ensure the integrity of the material

When installing steelwork, care must be taken with the following considerations:

Horizontal placement of steel to prevent puncture of the membrane

Plastic bar chairs or biscuit lids to distribute loads on the membrane

Minimization of wire clippings

Avoidance of oxy torch, grinding etc. over the membrane areas

Notification of identified defects whether at fault or not

It is important to notify all subcontractors the importance of any gas proof membrane, and to ensure integrity is maintained through all follow-on trades.

5.3 Construction Quality Assurance

Construction Quality Assurance (CQA) of the system is required via the provision of detailed validation measures which can be audited by regulatory bodies such as the DER / DoH and/or the Auditor to confirm the gas mitigation measures have been appropriately executed. This must be executed via a CQA plan, which can be developed and undertaken by CETCO or a suitably qualified independent inspector. CETCO have affiliations with two major consultancies in WA suitably trained in CETCO products.

5.4 Review and Approval of Gas Protection Measures

Once the final Site layout and subdivision have been decided, any building design drawings must be drafted to include Site specific gas mitigation measures with input from CETCO (or another suitably qualified remediation contractor / gas membrane installation specialists that can meet the above requirements / specifications at a minimum).

The building design plans incorporating the gas protection measures along with the CQA Plan for implementing these measures must be submitted to the DER/DoH and/or the Auditor for review and approval prior to any construction commencing at the Site.


6. COMMUNITY ENGAGEMENT

Given the relatively small size of the Site, the limited extent of the contamination, and given the relatively low levels of risk posed to surrounding human health and environment values, the contamination and landfill gas risk management measures outlined in this SMP will be accompanied by the following community consultation measures:

Table 14 Community Engagement

Task Timing Objective Measurable Outcomes

Stakeholder Identification

On approval of this SMP, prior to undertaking any further Site works

Identify community stakeholders who wish to participate in the engagement process

Records to demonstrate, at a minimum, that the following stakeholders were approached and invited to partake in the consultation process:

Adjacent land owners City of Gosnells DER DoH Representatives of the Site

development and construction contractors

Community Consultation Contact

Following stakeholder identification

Nominate a person who will be available to field questions from stakeholders

Name of contact(s), and phone number(s) and email address(es)

Consultation and Risk Communication

Following stakeholder identification

Communicate what management measures are being implemented at the Site to manage the contamination risks

Records of what information was communicated, and by what means communications were delivered to the identified stakeholders

Recording During Site development and construction

Maintenance of a record of communications

Records of contacts with the community and actions taken as a result of these contacts

Community Engagement Report

Following completion of construction

Documentation of the process

Report to summarise the community engagement process undertaken

The community engagement report, to be submitted in line with the above ‘Measurable outcomes’ must be prepared in line with the requirements outlined in the DER (2014) guidelines and a final copy of this report must be submitted to the DER.

In the event the client and/or DER require continued involvement of a Contaminated Sites Auditor a copy of this report must also be provided to the nominated Auditor.


6.1 Stakeholder Involvement

Information to be provided to community stakeholders identified above, and who wish to partake in the community engagement process, will include the following:

Table 15 Stakeholder Involvement

Information Timing

A one to two page flyer in non-technical language, in hard-copy or electronic format, as nominated by the identified stakeholders, to communicate the following information:

Summary of the identified contamination risks Future stages of the Site development To provide opportunities to comment and/or become involved in the engagement

process

Following the stakeholder identification task above

A one to two page flyer in non-technical language, in hard-copy or electronic format, as nominated by the identified stakeholders, to communicate the following information:

On results of the construction works Results of the post-construction monitoring To provide an opportunity to comment on the engagement process and provide

feedback

After the first round of post-construction monitoring

As specified in the preceding sections stakeholders will be given opportunities to provide input throughout the remainder of the project, commencing from approval of this SMP.

6.2 Future Site Owners and Occupiers

In the event the Site is offered for sale and/or lease, a copy of this SMP must be disclosed to the prospective purchaser(s) and/or lessee(s) and/or occupants prior to entering any legally binding agreements. Such disclosure:

Ensures that all future owners and occupiers of the Site are aware of their responsibilities in relation to implementing this SMP;

Ensures that all future owners and occupiers are aware of any residual environmental and health risks associated with the Site; and

Is in line with the requirement in the Contaminated Sites Act (2003) to provide formal disclosure to future owners, mortgagees in possession, and lessees prior to completion of a transaction on the land.


7. SITE MANAGEMENT PLAN

7.1 Timeframe for Site Management

The management measures outlined in this SMP apply to the following stages associated with the development of the Site:

Pre-Development / planning stage (Table 16)

Construction phase (Table 17)

Post Development (Table 18)

Timelines associated with specific management measures required to mitigate the identified risks to an acceptable level during each stage of development are outlined in the corresponding Table.

7.2 Management Measures

The following Sections outline the management measures required during each stage of Site development. These tables also outline the following:

Who is responsible for implementing the management measure(s)

Any documentation required to monitor / measure the effectiveness of the management measure(s)

Timeframe(s) for implementation of each of the management measure(s)


7.2.1 Pre-Development / Planning Stage

Table 16 outlines the management measures required during the pre-development / planning stage for the contamination risks identified. It is expected that these management measures will be implemented during a period which:

Site construction and design plans are being finalised;

Suitable contractors are being sourced; and

Contamination risks are communicated to all identified stakeholders.

Table 16 Management Measures – Pre-Development / Planning Stage

Media Management Measure Timeframe Responsibility Documentation / Reporting

All Communication of the risks outlined in this document (Section 4)

During the due diligence phase of any potential purchase of the Site

Following purchase of the Site during community engagement

Current Site owner Potential purchaser Identified stakeholders

Disclosure under the Contaminated Sites Act via Form 6

Flyer to be circulated as outlined in Table 15 following Stakeholder identification

Soil Restrict unmitigated access to soil via relevant Contaminated Sites Act 2003 administrative measures (e.g. Site classification and notice on the land titles).

Upon re-classification of the Site. Auditor DER/DoH

Site classification and notice on title under the Contaminated Sites Act 2003 to restrict access to soil.

Groundwater

Restrict unmitigated access to groundwater via relevant Contaminated Sites Act 2003 administrative measures (e.g. Site classification and notice on the land titles banning abstraction of groundwater for any purpose)

Upon re-classification of the Site. Auditor DER/DoH

Site classification and notice on title under the Contaminated Sites Act 2003 to restrict abstraction of groundwater from the Site.

Landfill Gas Develop design specifications for any proposed buildings at the Site incorporating appropriate gas membrane specifications and installation guidelines in accordance with Section 5.4.

During development of design plans for proposed buildings on-Site

Site owner (responsible for developing the Site)

Site developer Nominated construction contractor Qualified remediation contractor / gas

membrane installation specialists

Design specifications to be reviewed and endorsed by the Auditor and/or DER/DoH to ensure adequacy of the proposed gas membrane specifications


7.2.2 Construction Phase

Table 17 outlines the management measures required during the construction phase for the contamination risks identified. It is expected that these management measures will be implemented during the following activities:

Site preparation works

Any ground disturbing works

Site construction

Table 17 Management Measures – Construction Phase


Soil

Construction Environmental Management Plan (CEMP), which outlines the following:

Provision and maintenance of: o Appropriate signage on Site; o Perimeter fencing with shade cloth for wind break; and o Restricted public access.

For purposes of this SMP (in addition to typical and legally-required contractor safety management systems) the CEMP must include a safety management plan, which includes details on the application of the appropriate hierarchy of management controls (i.e. elimination, substitution, engineering, standard work practices, administrative controls and appropriate PPE) to minimise the risks of encountering impacted soil during Site development.

Limitations on the duration and depth of ground disturbing activities such as during installation of underground utilities and gas protection measures. Depth of ground disturbing activities should be limited to:

o the upper 0.5m of the capping layer on Lot 521; and o the upper 0.3m of the capping layer on Lots 522 and 523

Dust and asbestos monitoring requirements in accordance with DER (2011) and DoH (2009).

Asbestos monitoring must include: o Baseline monitoring to establish ambient conditions prior to any ground

disturbing activities; o Personal (occupational) and ambient air monitoring for airborne asbestos

fibres during ground disturbing activities; o Maintaining 24 hour turnaround on laboratory analyses of airborne

asbestos monitoring filters; o Reviewing monitoring results daily/on receipt from the laboratory to

The CEMP along with the safety management plan must be prepared, approved and reviewed by all construction contractors involved in the construction phase prior to commencement of any works on-Site. The CEMP must apply throughout the period that ground disturbing activities are on-going on Site and/or as long as excavations remain open.

Preparation of the CEMP / safety management plan:

Site owner (responsible for developing the Site); and/or

Site developer Compliance with the CEMP / safety management plan

Nominated construction contractor(s) and sub-contractor(s) conducting ground disturbing activities on-Site

Qualified remediation contractor / gas membrane installation specialists

The CEMP / safety management plan are to be prepared for review and endorsement by the Auditor and/or DER/DoH prior to commencement of any works on-Site. The Site development schedule should highlight the location, timing and duration of any ground disturbing activities, so that appropriate risk control measures in accordance with the CEMP may be planned and implemented appropriately. If any fill is to be brought onto Site, documentation is required to:

Record the volumes; Locations used on-Site; and Certify that it is clean or has

originated from a virgin source.

Document ID: W15038_01 Rev 1.docx Revision: 1 Revision Date: 31/03/2016

Media Management Measure Timeframe Responsibility

determine if management measures are adequate; and o Making all air monitoring results available to all contractors, by posting in

shared amenities areas or by making direct contact with the relevant personnel.

Dust suppression in all areas of the Site where ground disturbing activities are taking place.

Delineation of work zones to ensure that the correct Site personnel and visitors use the appropriate PPE during ground disturbing activities (including all times when excavations are left open);

Providing bin(s), doubled-lined with plastic, for containment of any fragments of suspected ACM that are encountered during Site construction works;

Disposal of all suspected ACM in sealed double-plastic at an appropriate off-Site waste disposal facility;

Handling of suspected ACM undertaken by qualified persons; Requirements for the importation of certified clean fill wherever necessary to level the

Site and/or achieve the desired elevations, eliminating the requirement for cut-and-fill earthworks; and

Requirements for installation of stormwater management controls to prevent run-off from transporting potentially impacted soil off-Site.

Groundwater

Baseline groundwater monitoring event at all available wells by a qualified environmental consultant.

Prior to any ground disturbing works or any construction works at the Site and prior to decommissioning any groundwater monitoring wells.

Site owner respdeveloping the

Conduct a survey to identify any groundwater abstraction wells/bores within 500m down hydraulic gradient of the Site, including requesting from property owners/occupants on what the bores/wells are used for. Prior to conducting this survey, a groundwater gauging round should be completed to accurately determine the groundwater flow direction at the Site.

Prior to any ground disturbing works or any construction works at the Site, for inclusion in the Baseline groundwater monitoring report.


Appropriate decommissioning of all groundwater monitoring wells existing within the footprint of any ground disturbing works or any construction works at the Site to ensure they do not become vertical conduits and/or contaminant migration post development. Decommissioning is to include the following:

Extraction of the casing of the monitoring wells (if possible) Filling the resultant hole with bentonite to the surface If extraction of the casing is not possible, the casing should be filled with bentonite.

Prior to any ground disturbing works or any construction works at the Site.




Secure all groundwater monitoring wells existing adjacent to and beyond the footprints of any ground disturbing works and any construction works at the Site so that they are not inadvertently destroyed.

Prior to commencement of ground disturbing activities.

Site owner responsible for developing the Site

Nominated construction contractor

Not applicable

Stormwater soak wells must not be installed on-Site. All stormwater must be captured within a network of sealed drains on-Site and discharge to the local off-Site stormwater drainage system.

During construction as warranted by the construction schedule.

Site developer Nominated construction

contractor Not applicable

Installation of replacement groundwater monitoring wells (with lockable covers). After ground disturbing works and construction works are completed.

Site owner responsible for developing the Site.

Inclusion of details of replacement wells (including locations and logs, etc.) in the Annual Groundwater and Landfill Gas Monitoring Report (see below).

On-going groundwater monitoring by a qualified environmental consultant. Biannually, for the duration of Site development, of all available monitoring wells.


Preparation of an Annual Groundwater and Landfill Gas Monitoring Report (see documentation below under ‘Landfill Gas’).

Landfill Gas

Baseline landfill gas monitoring of all available wells by a qualified environmental consultant.

Prior to any ground disturbing works or any construction works at the Site and prior to decommissioning any landfill gas monitoring wells.


Preparation of a Baseline Groundwater and Landfill Gas Monitoring Report .

Landfill gas monitoring by a qualified environmental consultant as follows:

Installation of in situ devices (such as GasClam) at strategic positions at the development Site to continuously log landfill gas data; and

Weekly download of data and review to identify trends (if feasible based on actual development footprint); or

Manual landfill gas monitoring using an infra-red gas analyser

During ground disturbing works and during the period of construction.


Continuous or periodic (based on the nominated methodology) landfill gas data set through development phase of project.

Preliminary reports, providing the monitoring data in tabular form for purposes of risk communication prior to and during Site development.

Inclusion of the complete dataset in the Annual Groundwater and Landfill Gas Monitoring Report.



Appropriate decommissioning of all landfill gas monitoring wells existing within the footprint of any ground disturbing works or any construction works at the Site to ensure they do not become vertical conduits and/or contaminant migration post development. Decommissioning is to include the following:

Extraction of the casing of the monitoring wells (if possible) Filling the resultant hole with bentonite to the surface If extraction of the casing is not possible, the casing should be filled with bentonite.

Prior to any ground disturbing works or any construction works at the Site.


Inclusion of the number and location of wells decommissioned in the Baseline Groundwater and Landfill Gas Monitoring Report.

Secure all landfill gas monitoring wells existing adjacent to and beyond the footprints of any ground disturbing works and any construction works at the Site so that they are not inadvertently destroyed.

Prior to commencement of ground disturbing activities.

Site owner responsible for developing the Site. Not applicable.

Preparation of a Construction Quality Assurance (CQA) Plan for the installation of the nominated gas protection measures in accordance with Section 5.3.

As early as possible during the planning stage following finalisation of design plans for buildings and prior to commencement of construction.


The CQA Plan is to be prepared for review and endorsement by the Auditor and/or DER/DoH prior to commencement of any construction works on-Site.

Integrate the landfill gas protection measures with the Site development and construction works in accordance with Section 5.2.1 and including the following:

Proprietary gas resistant membrane to reasonable levels of workmanship, free of defects, damage, punctures, or any leaks beneath all floor slabs and all building footprints with integrity testing and independent validation;

Sealing of all floor slab joints and floor slab penetrations; Design and construction of all utility service trenches, slabs, hardstand areas etc. to

ensure that landfill gases do not accumulate beneath or inside structures or migrate off-Site, and to ensure that gases can vent to atmosphere in a controlled manner; and

Integrity testing and independent validation of the integrity of the installed membrane. Technical specifications for suitable gas protection measures and integrity (smoke) testing of installed membranes are presented in Appendix B. Typical construction details for varying types of applications of this membrane in buildings are presented in Appendix C.

During construction of the sub-slab of all proposed buildings at the Site.

Integrity testing to be completed following installation of the membrane, prior to installation of the slab.

Site developer Nominated construction

contractor


Report on the testing of the gas resistant membrane validating its integrity and submission to the Auditor and/or DER/DoH if required.

Installation of suitable replacement landfill gas monitoring wells (with lockable covers). After ground disturbing works and construction works are completed. Site owner responsible for developing the Site.

Inclusion of details of replacement wells (including locations and logs, etc.) in the Annual Groundwater and Landfill Gas Monitoring Report (see below).

Landfill gas monitoring biannually, to include monitoring, for the duration of Site development, of all available monitoring wells.

Throughout the duration of Site development works.


Preparation of an Annual Groundwater and Landfill Gas Monitoring Report.


7.2.3 Post Development

Table 18 outlines the management measures required once the Site has been developed.

Table 18 Management Measures – Post Development


Soil

Same management measures as detailed in Table 17, but only triggered when any post-development ground disturbing activities are required (e.g. maintenance of underground services and/or if upgrades/additions to the Site are proposed).

Prior to and during any maintenance, upgrade works or additions / extensions to buildings on-Site. (See management measures outlined in Table 16 for specific timeframes for each requirement).

Site owner responsible for any Site upgrades / extensions

Intrusive maintenance workers

As per relevant documentation / reporting requirements outlined in Table 17.

Groundwater Biannual groundwater monitoring by a qualified environmental consultant. For one year post development, followed by an updated risk assessment. Site owner

Annual Groundwater and Landfill Gas Monitoring and Risk Assessment Report (see below).

Landfill Gas

Maintenance and inspection of landfill gas protection measures, infrastructure, equipment and monitoring network.

Quarterly or until a risk assessment can demonstrate that this is no longer required.

Site owner responsible for ensuring maintenance and inspections are completed at the required frequency

Auditor, DER and DoH for applying a memorial on the Title stipulating this requirement

Site classification and notice on title under the Contaminated Sites Act 2003 to perform quarterly maintenance or until no longer required on the basis of sound risk assessment.

Quarterly monitoring at all landfill gas monitoring wells and monitoring of gas levels inside the completed Site structures, followed by an updated risk assessment.

For one year post development. Site owner Annual monitoring and risk assessment report, to be combined with the above groundwater report


7.3 Contingency Measures

Table 19 outlines the contingency triggers and measures that may apply to the Site at any time during ground disturbing works or construction and/or at any time during occupation of the developed Site.

Table 19 Contingency Measures

Media Scenario Trigger Level Contingency Measures

Soil

Contractors and/or subcontractors do not adhere to the approved safety management plan. As observed by the construction manager.

Immediately stop works (excluding dust suppression, monitoring and other safety and environmental management controls) until contractors and/or subcontractors provide assurance that they will adhere to the approved safety management plan.

Revisit the SMP with contractors to educate and highlight the potential for risk unless the SMP is followed appropriately.

Unnecessarily prolonged and/or excessive ground disturbing activities (includes open excavations).

Excavations deeper than the depth of excavation (0.5m on Lot 521 and 0.3m on Lots 522 and 523)

Direct contractors to expedite ground disturbing activities and to close any open excavations.

Reschedule ground disturbing activities to a more suitable phase of Site works.

Excessive dust generation. As highlighted by any complaint from the community or workers, and/or as determined by visual or other monitoring.

Stop works until adequate dust suppression measures are in place. This may involve the inclusion of additional suppression measures to those already in place.

Contaminated fill, or suspected contaminated fill, is brought to Site.

If the fill has any odours, evidence of acid sulphate generation, foreign debris, unnatural staining, suspected ACM, or if the fill has originated from a known/ suspected contaminated site, etc.

Isolate the contaminated/ suspected contaminated fill and undertake fill characterisation sampling prior to placing the fill on Site.

Review the fill characterisation analyses to determine if the fill may remain on Site or if the fill is to be removed from Site, as appropriate.

Stormwater event transports soil/sediment anywhere off-Site. Not applicable Contain and collect all soil/ sediment transported off- Site and return it to the Site. Do not undertake any further earthworks (importing fill or excavations) until the Site

drainage controls are reviewed and upgraded as necessary.

Nuisance dusts, odours and/or noise. As highlighted by any complaint from the community or workers, and/or as determined by visual or other monitoring.

Stop all works associated with the reported nuisance(s) and review work procedures, limits of excavations and use of equipment and address the nuisance accordingly.


Media Scenario Trigger Level Contingency Measures

Suspected/ confirmed ACM is not being collected immediately upon discovery for containment in appropriately labelled bin(s), double-lined with plastic.

Not applicable.

Do not undertake any further ground disturbing works until a visual assessment is made of the area(s) where suspected/ confirmed ACM has been sighted.

Manually collect the pieces of suspected/ confirmed ACM if the above assessment deems it practical to do so.

If the assessment deems it impractical to manually collect the pieces of suspected/ confirmed ACM then sampling will be undertaken per the NEPM requirements (which supersede DOH, 2009) to quantify the amount of asbestos found, and to assess the risk of continuing ground disturbing activities.

If the risks of continued ground disturbing activities cannot be effectively or efficiently managed then, as a contingency measure, the area will be:

o Covered with a geotextile marker layer with clean fill or a permanen

site management planmarch 2016 site management plan lot 9005 allott way maddington wa prepared for...

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