r001 mobil northcote audit report...

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Environmental Audit Former Mobil Northcote Service Station (VO1003) Corner St Georges and Arthurton Roads, Northcote, Victoria EPA Reference No. 48726-2

24 JANUARY 2011

Prepared for

Mobil Oil Australia Pty Ltd 12 Riverside Quay Southbank VIC 3006

43512483

Former Mobil Northcote SS (VO1003)

43512483/R001/A i

Table of Contents

Executive Summary ................................................................................................vii

Statement of Environmental Audit..........................................................................xi

1 Introduction .......................................................................................................1

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

1.2 Purpose of Report..............................................................................................1

1.3 Parties Involved .................................................................................................2

1.4 Auditor’s Support ..............................................................................................2

2 Environmental Audits (Contaminated Land) ..................................................3

3 Scope and Methodology of the Audit ..............................................................5

3.1 Audit Scope ........................................................................................................5

3.2 Audit Methodology ............................................................................................5

3.3 Reports Reviewed by the Auditor ....................................................................6

4 Site Description.................................................................................................8

4.1 Site Location ......................................................................................................8

4.2 Land Characteristics .........................................................................................8

4.3 Property Description .........................................................................................8

4.3.1 Certificates of Title...........................................................................................................8 4.3.2 Land Use Zone .................................................................................................................8

4.4 Proposed Use of the Site ..................................................................................9

4.5 Neighbouring Land Uses ................................................................................10

4.6 Topography, Stormwater Runoff and Natural Watercourses ......................10

4.7 Regional Geology and Hydrogeology............................................................10

4.8 Site Geology and Hydrogeology ....................................................................12

4.9 Groundwater Use in the Area .........................................................................14

5 Site History ......................................................................................................15

5.1 Introduction ......................................................................................................15

5.2 Historical Overview..........................................................................................15

5.3 Potential Contaminants of Concern...............................................................16

6 Beneficial Uses and Environmental Quality Criteria....................................17

6.1 General..............................................................................................................17


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6.2 Land ..................................................................................................................17 6.2.1 Human Health.................................................................................................................18 6.2.2 Maintenance of Ecosystems.........................................................................................19 6.2.3 Production of Food, Flora and Fibre............................................................................20 6.2.4 Buildings and Structures ..............................................................................................20 6.2.5 Aesthetics.......................................................................................................................21

6.3 Groundwater.....................................................................................................21

6.3.1 Maintenance of Ecosystems.........................................................................................22 6.3.2 Agriculture, Parks and Gardens...................................................................................22 6.3.3 Stockwatering ................................................................................................................23 6.3.4 Industrial Water Use ......................................................................................................23 6.3.5 Primary Contact Recreation..........................................................................................24 6.3.6 Buildings and Structures ..............................................................................................24

6.4 Surface Water...................................................................................................25

7 Environmental Site Assessment....................................................................26

7.1 Environmental Site Assessment (Handex, 1998)..........................................26

7.2 Tank Excavation Assessment Report (ITE, 2004).........................................27

7.3 Phase 1 Environmental Site Assessment (Coffey, 2006) .............................30

7.4 Inspection and Evaluation of Hazardous Materials (EnviroProtect, 2006) .......................................................................................31

7.5 Further Tank Excavation Assessment (Coffey, 2007) ..................................31

7.6 Phase 2 Environmental Site Assessment (Coffey, July 2008a)...................33

7.7 Soil Validation Assessment (Coffey, December 2008b)...............................35

7.8 Post Phase 2 Environmental Site Assessment (Coffey, December 2008c) .............................................................................................37

7.9 Annual Groundwater Monitoring Event (Coffey, February 2009a) ..............39

7.10 Groundwater Fate and Transport Modelling (Coffey, July 2009b) ..............41

7.11 2009 Post Phase 2 Environmental Site Assessment (Coffey, July 2009c)........................................................................................................42

7.12 Groundwater Monitoring Event (Coffey, February 2010a) ...........................43

7.13 Health Risk Assessment (Coffey, July 2010b) ..............................................44

7.14 Further Tank Excavation Assessment (Coffey, April 2010c) .......................45

7.15 Interim Groundwater Monitoring Event (Coffey, August 2010d) .................46


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8 Quality of Site Assessment Data ...................................................................48

8.1 General..............................................................................................................48

8.2 Sampling Spatial Density ................................................................................48 8.2.1 Soil...................................................................................................................................48 8.2.2 Groundwater...................................................................................................................49

8.3 Field Protocols .................................................................................................49

8.4 Laboratory Method Protocols.........................................................................51

8.5 Analytical Data Validation Procedure ............................................................56 8.5.1 Analytical Data Validation.............................................................................................57 8.5.2 Limits of Reporting ........................................................................................................73

8.6 Auditor’s Overall Comment on Data Quality .................................................77

9 Environmental Condition of Site....................................................................78

9.1 Imminent Environmental Hazards ..................................................................78

9.2 Site Condition Prior to Remediation (1998)...................................................78 9.2.1 Soil...................................................................................................................................78 9.2.2 Perched Water................................................................................................................78 9.2.3 Groundwater...................................................................................................................79

9.3 Infrastructure Decommissioning/Site Remediation (2003 – 2010) ..............79

9.3.1 Soil...................................................................................................................................79 9.3.2 Groundwater...................................................................................................................80

9.4 Final Condition of the Site ..............................................................................80

9.4.1 Soil...................................................................................................................................80 9.4.2 Groundwater...................................................................................................................83

9.5 Auditor Verification Sampling ........................................................................84

10 Harm, Detriment or Risk to Beneficial Uses of the Site ...............................85

10.1 Soil ....................................................................................................................85

10.1.1 Maintenance of Ecosystems and Production of Food, Flora and Fibre...................85 10.1.2 Human Health.................................................................................................................86 10.1.3 Buildings and Structures ..............................................................................................87 10.1.4 Soil Aesthetics ...............................................................................................................87

10.2 Groundwater.....................................................................................................88

10.2.1 Maintenance of Ecosystems.........................................................................................88


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iv 43512483/R001/A

10.2.2 Agriculture, Parks and Gardens...................................................................................89 10.2.3 Stockwatering ................................................................................................................90 10.2.4 Industrial Water Use ......................................................................................................90 10.2.5 Primary Contact Recreation..........................................................................................90 10.2.6 Buildings and Structures ..............................................................................................91

10.3 Groundwater (CUTEP) .....................................................................................91

11 Auditor's Conclusions ....................................................................................94

11.1 Findings of the Audit .......................................................................................94

11.2 Issue of Statement of Environmental Audit ..................................................96

11.3 Obligation to Provide Statement to Future Owners/Occupiers...................97

12 References.......................................................................................................98

13 Limitations.....................................................................................................101

Tables (in text) Table 1 Summary of Audit Information ......................................................................................... vii Table 2 Physical Site Information ................................................................................................ viii

Table 3-1 Auditor Site Visits.............................................................................................................. 5 Table 3-2 Reports Reviewed by the Auditor ..................................................................................... 6 Table 4-1 Surrounding Land Uses .................................................................................................. 10 Table 4-2 Generalised Geological Profile ....................................................................................... 12 Table 5-1 Potential Site Contaminants of Concern......................................................................... 16 Table 7-1 Summary of Site Excavations......................................................................................... 28 Table 7-2 Summary of Soil Stockpiles ............................................................................................ 29 Table 8-1 Soil Analytical Methods and Corresponding Laboratory LORs ...................................... 52 Table 8-2 Water Analytical Methods and Corresponding Laboratory LORs................................... 54 Table 8-3 Analytical Data Validation – ESA (Handex, 1998).......................................................... 57 Table 8-4 Analytical Data Validation - TEA (ITE, 2004).................................................................. 58 Table 8-5 Analytical Data Validation - Further TEA (Coffey, 2007) ................................................ 59 Table 8-6 Analytical Data Validation - Phase 2 ESA (Coffey, 2008a) ............................................ 61 Table 8-7 Analytical Data Validation - Soil Validation Assessment (Coffey, 2008b) ...................... 62 Table 8-8 Analytical Data Validation - Post Phase 2 ESA (Coffey, 2008c) .................................... 64


Table of Contents

43512483/R001/A v

Table 8-9 Analytical Data Validation - Annual GME (Coffey, 2009a) ............................................. 66 Table 8-10 Analytical Data Validation – 2009 PP2 ESA (Coffey, 2009c) ......................................... 67 Table 8-11 Analytical Data Validation - GME (Coffey, 2010a).......................................................... 69 Table 8-12 Analytical Data Validation - Further TEA (Coffey, 2010c) .............................................. 70 Table 8-13 Analytical Data Validation - Interim GME (Coffey, 2010d).............................................. 72

Tables (attached) Table 1 Adopted Soil Criteria for Beneficial Uses of Land

Table 2 Adopted Groundwater Quality Objectives

Table 3 Exceedances of Adopted Soil Criteria after Remediation/Validation

Table 4 Exceedances of Adopted Groundwater Quality Objectives after Remediation/Validation

Figures Figure 1 Site Locality Plan

Figure 2 Site Features Plan

Figure 3 Groundwater Contour Plan (November 2010)

Figure 4 Registered Groundwater Bore Locations (Statewide Groundwater Database)

Figure 5 Handex Soil and Groundwater Well Locations

Figure 6 Former UST Locations and ITE Excavation Extents (2003)

Figure 7a Excavation Extents (March 2005)

Figure 7b Excavation Extents (May 2005)

Figure 7c Excavation Extents (June 2005)

Figure 7d Excavation Extents (July 2005)

Figure 8 Final Excavation Extents (2007 – 2010)

Figure 9 Residual Soil Contamination in NE Corner of Site (February 2010)

Figure 10 Groundwater Quality Restricted Use Zone (GQRUZ)

Plates Plate 1 16 February 2010: Widening of St Georges Road (eastern site boundary)

Plate 2 16 February 2010: Retaining wall along the western site boundary

Plate 3 16 February 2010: NDCR backfill across the site


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vi 43512483/R001/A

Appendices Appendix A Glossary of Terms Appendix B Certificate of Title Appendix C City of Darebin Planning Schemes and Overlays Appendix D Borelogs Appendix E Victorian Groundwater Database Search Results Appendix F Copies of Site Assessment Reports (Refer to Attached CD) Appendix G Auditor Verification Results and COCs Appendix H Auditor CUTEP Submission and EPA Determination (refer to Attached CD) Appendix I Nitrate-N Criteria Documentation


43512483/R001/A vii

Executive Summary

ENVIRONMENTAL AUDIT (CONTAMINATED LAND)

Table 1 Summary of Audit Information

EPA file reference number: 48726-2

Auditor: Darryl Strudwick

Auditor term of appointment: 18 November 2007 to 17 November 2011

Name of person requesting audit: Mr Robert Samardjiev of Mobil Oil Australia Pty Ltd

Relationship to premises/location: Representative of site owner (at the time of the Audit request)

Date of request: 17 June 2008

Date EPA notified of audit: 17 June 2008

Completion date of the audit: 24 January 2011

Reason for audit: Voluntary, to facilitate site divestment

Current land use zoning: Residential 1 Zone (R1Z)

EPA region: Yarra

Municipality: Darebin City Council

Dominant – Lot on plan: Land in Plan of Consolidation 100143, Volume 8836, Folio 772, Parish of Jika Jika, County of Bourke

Additional – Lot on plan(s): N/A

Site / premises Street/Lot Street Name Street type Street suffix Suburb Postcode

137 St Georges Road n/a Northcote 3070

GIS coordinate of site centroid Longitude/Northing (GDA94): Latitude/Easting (GDA94):

Easting 323042 Northing 5817952

Site area (hectares) 0.202 hectares

Members and categories of support team utilised:

Peter McGowan (Environmental chemistry – analytical) Jackie Wright (Contaminant transport and assessment of exposure pathways and risk)

Outcome of audit: Statement of Environmental Audit

Further work or requirements: Implementation of Conditions of Statement of Environmental Audit.


Executive Summary

viii 43512483/R001/A

Nature and extent of continuing risk: • Concentrations of TPH C15-C36, B(a)P, Total PAH and zinc in historical fill material beneath the footpath in the northeast of the site that exceed the adopted soil criteria for beneficial uses associated with low density residential use, public open space, high density residential use and commercial industrial use. The historical fill is also considered to be aesthetically unacceptable for low density residential use, high density residential use and public open space with accessible soils; and

• Concentrations of MTBE in groundwater in some wells on-site and potentially in groundwater located a short distance off-site are considered to preclude the beneficial uses Agriculture, Parks and Gardens and Primary Contact Recreation.

Table 2 Physical Site Information

Site aquifer formation: Newer Volcanics

Average depth to groundwater: Approximately 3.7 m

Groundwater segment: Segment B

Groundwater flow direction: South

Past use / site history: Vacant land and residential housing

Surrounding land use: North – Arthurton Road and commercial/residential South – Auburn Avenue and residential East – St Georges Road and residential West – Laneway and residential

Proposed future use: Residential land use

Summary Outcome of Audit This Environmental Audit Report has been prepared by Mr. Darryl Strudwick (an EPA appointed Environmental Auditor – Contaminated Land) of URS Australia Pty Ltd at the request of Mr Robert Samardjiev of Mobil Oil Australia Pty Ltd.

The site has historically been used as a petroleum service station with an associated workshop. Infrastructure at the site included eleven USTs, bowsers, fill points and associated fuel lines, sales building and workshop including triple interceptor trap and hydraulic hoist. The site was closed in about 1998 and decommissioned in 2003, and has undergone environmental assessment and remediation between 1998 and 2010.

All infrastructure relating to the former use has been removed. Remediation of the site comprised excavation and removal of contaminated soil. Soil covering virtually the entire site has been excavated to depths between 1.8 and 5.0m below ground surface. Soil remaining on site has been validated. Excavations were backfilled with imported fill material (mainly NDCR from commercial quarries).

The site owner (Mobil) proposes to divest the site for use consistent with its land use zone (ie. residential – R1Z). The proposed use of the site is unknown, however it is assumed to be residential.


Executive Summary

43512483/R001/A ix

After considering the environmental condition and beneficial uses of the site, the Auditor has assessed any harm, detriment or risk to those beneficial uses and concluded the following:

• The Auditor is not aware of any imminent environmental hazards that are associated with the site;

• Historical fill material, which could not be excavated due to its proximity to St Georges and Arthurton Roads and the presence of underground services, remains beneath the footpath in the northeast of the site. The historic fill contains concentrations of TPH C15-C36, B(a)P, Total PAH and zinc that exceed the adopted soil criteria for beneficial uses associated with low density residential use, public open space, high density residential use and commercial industrial use. The Auditor considers that the historic fill beneath the footpath in the northeast of the site represents a potential for harm, detriment or risk to those beneficial uses. The historical fill is also considered to be aesthetically unacceptable for low density residential use, high density residential use and public open space with accessible soils;

• Residual concentrations of TPH, ethylbenzene, Total PAH and B(a)P in a small number of samples of natural soil at depths of 2m bgs and 3.5m bgs exceed the adopted soil criteria for beneficial uses associated with low and high density residential use, public open space and commercial / industrial use. It is reasonable to expect that these soils would have a hydrocarbon odour if exposed. Staining of natural soil was also reported to have been observed in validation samples collected at the base of the three USTs removed from the northeast corner of the site. The stained natural soil was located at about 2.4m bgs underneath the fence line / edge of the footpath. The stained soil was not excavated, but was covered by “liquidfill” (i.e. cement slurry). Due to the depth of the stained and potentially odorous soils, it is unlikely that future site occupiers would come into contact with these soils via standard soil exposure (gardens / accessible soil). Further, it is considered unlikely that these measured concentrations would pose an unacceptable level of risk to future users of the site (including residents) via a pathway into buildings. The Auditor does not consider the concentrations of these compounds at the stated locations to represent a potential for harm, detriment or risk to beneficial uses of the site. If exposed during future construction or excavation (eg. in-ground swimming pool), soils at these locations may have a hydrocarbon odour;

• Natural soil and imported backfill (NDCR) at the site contains concentrations of metals (arsenic, barium, chromium, cobalt, copper, manganese, nickel and vanadium) above the adopted soil criteria for various beneficial uses. The Auditor considers these metals to be representative of background concentrations and not to represent a potential for harm, detriment or risk to beneficial uses of the site;

• The concentrations of dissolved metals (cadmium, copper, nickel and zinc) in groundwater exceed the GWQOs for the beneficial use maintenance of ecosystems (as well as agriculture, parks and gardens and primary contact recreation in the case of nickel in a single sample). The concentrations of these metals represent background conditions which are not considered to adversely affect the beneficial uses of groundwater;

• Concentrations of MTBE in groundwater in some wells on-site and potentially in groundwater located a short distance off-site are considered to preclude the beneficial uses Agriculture, Parks and Gardens and Primary Contact Recreation. These beneficial uses are neither existing nor likely at or in the vicinity of the site; and


Executive Summary

x 43512483/R001/A

• The concentrations of sulphate in groundwater in two wells (MW7 and MW11) at the site exceed the GWQOs for the beneficial uses stock watering, primary contact recreation, industrial water use and buildings and structures. The concentration of sulphate in groundwater from MW17 exceeds the GWQO for stockwatering. These concentrations of sulphate are considered to be anomalous and not related to activities at the site. As a result, these beneficial uses are considered to be limited (not precluded) by the reported sulphate concentrations;

• Based on the CUTEP submission by the Auditor to EPA, EPA determined that the Clean up (of polluted groundwater) to the extent practicable had occurred.

Due to the presence of contaminated (TPH C15-C36, B(a)P, Total PAHs and Zinc) and aesthetically impacted historical fill material located beneath the footpath in the northeast of the site, as well as the contamination of groundwater by MTBE resulting from site activities that precludes the beneficial uses Agriculture, Parks and Gardens and Primary Contact Recreation, the site is not considered to be suitable for all beneficial uses.

The Environmental Auditor makes the Statement as included at the front of this report. The Statement of Environmental Audit confirms that the site is suitable for the beneficial uses associated with low density residential use, public open space, high density residential use and commercial/industrial use, subject to conditions contained within the Statement.


43512483/R001/A xi

Statement of Environmental Audit

ENVIRONMENT PROTECTION ACT 1970

I, Darryl Strudwick, of URS Australia Pty Ltd, a person appointed by the Environment Protection Authority (“the Authority”) under the Environment Protection Act 1970 (“the Act”) as an environmental auditor for the purposes of the Act, having:

1. been requested by Mr Robert Samardjiev of Mobil Oil Australia Pty Ltd (Mobil) to issue a certificate of environmental audit in relation to the site located at 137 St Georges Road, Northcote, described as Land in Plan of Consolidation 100143, Volume 8836, Folio 772, Parish of Jika Jika, owned/occupied by Mobil Oil Australia Limited;

2. had regard to, amongst other things:

(i) Guidelines issued by the Authority for the purposes of Part IXD of the Act,

(ii) the beneficial uses that may be made of the site, and

(iii) relevant State environment protection policies/industrial waste management policies, namely:

— State Environment Protection Policy, Prevention and Management of Contamination of Land, June 2002;

— State Environment Protection Policy, Groundwaters of Victoria, December 1997; — Variation to State Environment Protection Policy, Waters of Victoria, June 2003.

in making a total assessment of the nature and extent of any harm or detriment caused to, or the risk of any possible harm or detriment which may be caused to, any beneficial use made of the site by any industrial processes or activity, waste or substance (including any chemical substance); and

3. completed an environmental audit report in accordance with section 53X of the Act, a copy of which has been sent to the Authority and the relevant planning and responsible authority.

HEREBY STATE that I am of the opinion that: The site is considered suitable for the beneficial uses associated with low density residential use, public open space, high density residential use and commercial/industrial use subject to the following conditions attached thereto:

• The concrete footpath (or similar physical barrier) covering the historical fill adjacent to St Georges and Arthurton Roads in the northeast of the site must be maintained. If the barrier is damaged or removed during site works, it must be reinstated as soon as possible to the same condition or better than prior to the disturbance;

• Should removal of the footpath covering the historical fill be proposed to enable landscaping / vegetation or direct soil access by future occupants, the historic fill material must be removed and replaced with soil that is suitable for the proposed use;

• Should removal of the footpath covering the historical fill be proposed to enable installation or maintenance of underground services, the historic fill material must be reinstated beneath the barrier or removed from the site in accordance with EPA requirements for the disposal or re-use of contaminated soil; and

• Groundwater at the site is polluted and must not be used for Agriculture, Parks and Gardens and Primary Contact Recreation.

The condition of the site is detrimental or potentially detrimental to any (one or more) beneficial uses of the site. Accordingly, I have not issued a Certificate of Environmental Audit for the site in its current condition, the reasons for which are presented in the environmental audit report. The terms and conditions that need to be complied with before a Certificate of Environmental Audit may be issued are set out as follows:


43512483/R001/A 1

1

1 Introduction

1.1 Background This Environmental Audit Report has been prepared by Darryl Strudwick (an EPA appointed Environmental Auditor – Contaminated Land) of URS Australia Pty Ltd (URS) at the request of Mr Robert Samardjiev of Mobil Oil Australia Pty Ltd (Mobil).

The Audit has been conducted in accordance with Part IXD of the Environment Protection Act 1970 and “Environmental Auditor (Contaminated Land), Guidelines for Issue of Certificates and Statements of Environmental Audit”, EPA Pub. No. 759.1, September 2007.

The Auditor has exercised professional judgement and had regard to State Environment Protection Policies, Industrial Waste Management Policies and national and state environmental guidelines, where relevant.

The site subject to this Environmental Audit is located at 137 St Georges Road, Northcote (corner Arthurton Road) (the “site”) and is described as Plan of Consolidation 100143, Volume 8836, Folio 772, Parish of Jika Jika, County of Bourke (refer Figure 1). The title area (which is the site area subject to this audit) extends beyond the former service station area to St Georges Road along the eastern boundary and to Arthurton Road along the north eastern boundary (refer to Figure 2). The Auditor understands that the intersection was widened some time ago by VicRoads and the service station area was reduced, however, the title was not rectified. The site was a former service station that was decommissioned in 2003 and has undergone environmental assessment and remediation between 1998 and 2010.

The site owner, Mobil, has undertaken this audit as part of a due diligence process to facilitate divestment of the site. The site is zoned as Residential 1 Zone (R1Z) under the City of Darebin Planning Scheme. The proposed use of the site is unknown, however is assumed to be for residential purposes.

Mr. Warren Pump of URS was initially engaged to conduct the Audit on 4 March 2002 and notified the EPA on 7 March 2002. However, due to his relocation overseas, Mr Pump notified EPA of termination of the audit on 11 June 2008. Mr. Darryl Strudwick of URS was engaged to conduct the Audit on 17 June 2008 and notified EPA on 17 June 2008.

1.2 Purpose of Report The purpose of this Audit Report is to evaluate whether the site being audited is suitable for any (all) beneficial uses and, if not, whether it is suitable for the existing or intended use, or for a range of uses consistent with the zoning of the land. Therefore, this Audit will assess the health and environmental risks from exposure to contaminated soil, vapours, and/or waters (including groundwater) found at the site with respect to its existing and potential beneficial uses. This includes the impact of the land on contiguous segments of the environment and adjacent land, and the possibility of adjacent land impacting adversely upon the environmental condition of the subject land.


1 Introduction

2 43512483/R001/A

1.3 Parties Involved The following is a list of parties involved in the Audit:

Site Owner(s): Mobil Oil Australia Pty Ltd Environmental Site Assessor(s): Coffey Environments Pty Ltd (2006 onwards);

IT Environmental (Australia) Pty Ltd (now Coffey Environments) (2003 - 2007); and Handex Australia Pty Ltd (1998).

Primary Laboratory Used by Assessor(s): Australian Government Analytical Laboratories (AGAL) Amdel Limited Australia (Amdel) Australian Laboratory Services Pty Ltd (ALS)

Secondary Laboratory Used by Assessor(s): Australian Government Analytical Laboratories (AGAL) MGT Environmental Consulting Pty Ltd (MGT) LabMark Environmental Laboratories Pty Ltd (LabMark) Amdel Limited Australia (Amdel)

Auditor: Mr. Darryl Strudwick (URS) Laboratory Used by the Auditor: MGT Environmental Consulting Pty Ltd (MGT)

1.4 Auditor’s Support The following URS personnel assisted the Auditor in completing this Environmental Audit:

Victoria Conlon (Senior Hydrogeogist) – Project co-ordination and management, site visits;

Kelly Dobson (Senior Environmental Scientist) – Project co-ordination and management, site visits, analytical data validation and reporting under instruction of the Auditor;

Rachael Hofmann (Environmental Engineer) – Project co-ordination and management, site visits, analytical data validation and reporting under instruction of the Auditor;

Brad Scott (Environmental Chemist) – Groundwater verification sampling;

Vera Levina (Hydrogeologist) – Review of fate and transport model under the instruction of the Auditor;

Jonathan Thom (Senior Environmental Scientist / Risk Assessor) – Review of risk assessment of MTBE in groundwater under instruction of the Auditor;

Victoria Lazenby (Senior Environmental Scientist / Risk Assessor) – Review of risk assessment of MTBE in groundwater under instruction of the Auditor; and

Katie Richardson (Senior Environmental Scientist / Risk Assessor) – Review of environmental quality objectives under instruction of the Auditor.

The Auditor used the following members of his expert support team in completing this Audit:

Jackie Wright (Contaminant transport and assessment of exposure pathways and risk) – Review of risk assessment of MTBE in groundwater.

Peter McGowan (Associate Environmental Chemistry- analytical) – Peer review of analytical data, data validation and advice regarding analysis of MTBE and sulphate.


43512483/R001/A 3

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2 Environmental Audits (Contaminated Land)

The Environmental Audit (Contaminated Land) system provides for an Environmental Auditor (Contaminated Land) to undertake an independent review of the environmental condition of a site and form an opinion regarding its suitability for any existing, intended or potential use. The system is designed to provide:

• Assurance to the community that a site is suitable for its intended use; • Assurance to prospective purchasers and other parties involved in property investment and

development regarding the condition of a site and any restrictions attached to that site; and • A link between the environmental condition of a site, the suitability of a site for use and the

statutory planning process.

The Environment Protection Act 1970 (the ‘Act’) creates a mechanism under which a ‘Certificate’ or ‘Statement’ of Environmental Audit may be issued by a person appointed as an Environmental Auditor (Contaminated Land) by the EPA, following the completion of an Environmental Audit. Environmental Audits are undertaken in accordance with the procedures as set out in the Act and guidelines for auditors issued by EPA.

Environmental Audits are defined in Section 4 of the Act and their use is described in Part IXD of the Act. The definition of an ‘Environmental Audit’ is:

“a total assessment of the nature and extent of any harm or detriment caused to, or the risk of any possible harm or detriment which may be caused to, any beneficial use made of any segment of the environment by any industrial process or activity, waste, substance (including any chemical substance) or noise1”.

In conducting a Environmental Audit, the Auditor must identify the beneficial use(s) that are to be protected for the site in question. The beneficial uses considered could include for example:

• human health and well being; • maintenance of natural or modified ecosystems (including wildlife); • aesthetic enjoyment and amenity; • production of food, flora and fibre; and • buildings and structures (with regard to corrosion, chemical degradation, fire or explosion risk

related to contamination).

With respect to Environmental Audits of contaminated land or potentially contaminated land, the primary function of the Environmental Auditor is to Audit the environmental condition of the site in question (in accordance with provisions of Part IXD of the Act) and conclude as to the suitability of the site for use.

In undertaking an Environmental Audit, an Auditor considers all necessary data related to the environmental condition of the site. In assessing the present environmental condition of a site, the Auditor may review any previous site contamination assessments and relevant documentation applying to the subject site, which may comprise at least the following:

• the basis for the identification of contamination on the site, including site history, land uses, planning, zoning and the process of site identification;

• relevant correspondence;

1 Noise is not a relevant consideration when conducting an Environmental Audit (Contaminated Land) but is a factor that can impact on beneficial use.


2 Environmental Audits (Contaminated Land)

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• demography of the locality; • geology/hydrogeology of the area; • quality of water resources, including groundwater and stormwater run-off; • chemical and physical characteristics of the soil and the contaminants; • characterisation of contamination, including the nature and mobility of contaminants, their depth

and spatial distribution; and • licences and/or trade waste agreements from environmental, waste management or waste water

management agencies.

The Auditor may undertake his or her own investigation at, and in the vicinity of, the site to confirm the findings of the site assessment and therefore satisfy him or herself of the environmental condition of the site.

After preparing an Audit Report, the Auditor’s conclusions regarding the site and its suitability for use are included in a Certificate or Statement of Environmental Audit.

If the Auditor considers it appropriate, the Auditor will issue a Certificate of Environmental Audit, and an accompanying Audit Report. The Auditor must decline to issue a Certificate if the Auditor is of the opinion that contamination of the site renders the site detrimental or potentially detrimental to any (one or more) beneficial use of the site. In such cases, the Auditor will issue a Statement of Environmental Audit (and an accompanying Audit Report), identifying the uses for which the Auditor considers the site suitable.

For the purposes of Auditing, the ‘site’ subject to the Environmental Audit is defined as “the land at a premises being Audited as a parcel of Land and all other elements of the environment associated with the land within the boundary of the parcel of land” (EPAV, Publication 759.1, September 2007).

‘Land’ refers to the element of the environment that includes:

• soil, fill, rock, weathered rock and sand; • the vapour and liquids within interstitial space, in the unsaturated zone of (a); and • sub-aqueous sediment.

A glossary of terms and explanatory notes used in this Audit report are presented in Appendix A.

EPA has prepared guidelines in relation to Environmental Audits, which are entitled Environmental Auditor (Contaminated Land), Guidelines for Issue of Certificates and Statements of Environmental Audit, (Pub. No.759.1, September 2007). This Audit has been undertaken in accordance with these guidelines.

The Auditor must have regard to relevant State Environment Protection Policies and Industrial Waste Management Policies and other guideline documents when conducting an Environmental Audit. These include:

• State Environment Protection Policy (Prevention and Management of Contamination of Land); • State Environment Protection Policy (Groundwaters of Victoria); • State Environment Protection Policy (Waters of Victoria) and catchment specific schedules as

appropriate for the Audit in question; • State Environment Protection Policy (The Air Environment); and • Environment Protection (Industrial Waste Resource) Regulations.

Additional references for Auditors and for the Auditing system, which have been directly or indirectly considered as part of this Audit, are listed in Section 12 of this report.


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3

3 Scope and Methodology of the Audit

3.1 Audit Scope The Audit scope relates to the assessment of the environmental condition of the site (corner St Georges and Arthurton Roads, Northcote) in relation to contamination by previous land uses and its suitability for its proposed and other uses. This includes an assessment of potentially contaminating activities and the potential for contamination at the site to adversely affect beneficial uses at and off-site as well as for surrounding land uses (current and historic) to affect beneficial uses of the site.

3.2 Audit Methodology In conducting this Environmental Audit, the Auditor and/or his representative has:

• reviewed, evaluated, and commented on (where necessary) relevant site assessment reports (refer to Section 3.3) to gain an understanding of the environmental condition of the site and the completeness/adequacy of the site assessment (including Quality Assurance/Quality Control (QA/QC));

• reviewed and provided comments on the scope of investigation works provided by the site assessor (during the Audit period);

• inspected the site on at least four occasions. The date and purpose of each visit is provided in the table below. The site visits were mainly to inform the auditor as to the status of the site with regard to site investigation. The Auditor notes that the previous Auditor (Mr Warren Pump) and/or his representative visited the site on four occasions between March 2007 and May 2008. These are also shown in Table 3-1 below (shaded cells).

Table 3-1 Auditor Site Visits

Date Purpose/Activity Who Attended

27 March 2007 Initial site visit prior to ESA works. Warren Pump and Victoria Conlon

11 May 2007 Inspection of excavation works. Victoria Conlon

20 March 2008 Inspection of excavation works and three offsite tanks in NE corner.

Warren Pump and Victoria Conlon

26 May 2008 Inspection of UST removal. Victoria Conlon

31 July 2008 Inspection of groundwater sampling and collection of auditor verification groundwater sample. Brad Scott

11 February 2010 Inspection of UST excavation in NE corner of site. Rachael Hofmann

16 February 2010 Inspection of UST excavation in NE corner of site and collection of auditor verification soil sample.

Darryl Strudwick and Rachael Hofmann

15 July 2010 Inspection of groundwater sampling. Kelly Dobson

• collected a sample of groundwater from MW2 in the centre-north of the site in order to verify the environmental condition of groundwater at the site;

• satisfied himself of the environmental condition of the site; • identified the beneficial use(s) to be protected; • assessed the harm, detriment or risk posed by the condition of the site to beneficial uses to be

protected; • drawn conclusions as to the suitability of the site in its final condition for its existing and intended

use; and • prepared this audit report and Statement of Environmental Audit (SoEA) (attached).



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3.3 Reports Reviewed by the Auditor In undertaking this Environmental Audit, the Auditor has reviewed the documents in the following table.

Table 3-2 Reports Reviewed by the Auditor

Author Title

Handex Australia Pty Ltd (Handex), July 1998

Environmental Site Assessment, Closed Service Station Facility, Cnr St Georges Road and Arthurton Street, Northcote, Victoria, Site No. VO1003, 16 July 1998. Reference VO 1009-R1

IT Environmental (Australia) Pty Ltd (ITE), July 2004

Tank Excavation Assessment Report, Former Northcote Service Station, Corner of St. Georges and Arthurton Street, Northcote, Victoria, 8 July 2004. Reference J306207B

Coffey Environments Pty Ltd (Coffey), July 2006

Phase 1 Environmental Site Assessment, Mobil Service Station Northcote (VO1003), Corner St. Georges and Arthurton St, Northcote, Victoria, 25 July 2006. Reference ENVIABTF06207DA

EnviroProtect Pty Ltd, December 2006

Inspection and Evaluation of Hazardous Materials, Part 6 Asbestos & Hazardous Materials, prepared for JFTA Pty Ltd at Mobil Service Station – 137-151 St. Georges Road, Northcote (VO1003), December 2006.

Coffey Environments Pty Ltd (Coffey), January 2007

Further Tank Excavation Assessment Report, Former Mobil Service Station, Corner St. Georges and Arthurton Road, Northcote, Victoria, 9 January 2007. Reference ENVIABTF06207CA

Coffey Environments Pty Ltd (Coffey), July 2008a

Phase 2 Environmental Site Assessment Report, Former Mobil Northcote Service Station (VO1003), Corner St Georges and Arthurton Road, Northcote, VIC 3070, 28 July 2008. Reference ENVIABTF06207FA

Coffey Environments Pty Ltd (Coffey), December 2008b

Soil Validation Assessment, Mobil Northcote Service Station (VO1003), Corner of St. Georges and Arthurton Roads, Northcote VIC 3070, 17 December 2008. Reference ENVIABTF06207EA

Coffey Environments Pty Ltd (Coffey), December 2008c

Post Phase 2 Environmental Site Assessment, Former Mobil Northcote Service Station (VO1003), Corner St Georges and Arthurton Road, Northcote, VIC 3070, 19 December 2008. Reference ENVIABTF06207GA

Coffey Environments Pty Ltd (Coffey), February 2009a

Annual Groundwater Monitoring Event, Former Mobil Northcote Service Station (VO1003), Corner St Georges and Arthurton Road, Northcote, VIC 3070, 3 February 2009. Reference ENVIABTF06207HA

Coffey Environments Pty Ltd (Coffey), July 2009b

Groundwater Fate and Transport Modelling – Former Mobil Service Station Northcote (VO1003), 137-151 St Georges Road, Northcote, VIC 3070, 9 July 2009. Reference ENVIABTF06207JA

Coffey Environments Pty Ltd (Coffey), July 2009c

2009 Post Phase 2 Environmental Site Assessment, Former Mobil Northcote Service Station (VO1003), Corner of St Georges Road and Arthurton Road, Northcote, Victoria, 10 July 2009. Reference ENVIABTF06207MA

Coffey Environments Pty Ltd (Coffey), February 2010a

Groundwater Monitoring Event, Former Mobil Northcote Service Station (VO1003), Corner of St Georges Road and Arthurton Road, Northcote, Victoria, 18 February 2010. Reference ENVIABTF06207OA

Coffey Environments Pty Ltd (Coffey), July 2010b

Health Risk Assessment, Former Mobil Northcote Service Station (VO1003), 137-151 St Georges Road, Northcote, Victoria 3070, 12 July 2010. Reference ENVIABTF06207IA



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Coffey Environments Pty Ltd (Coffey), April 2010c

Further Tank Excavation Assessment Report, Former Mobil Northcote Service Station (VO1003), 137-151 St Georges Road, Northcote, Victoria, 29 April 2010. Reference ENVIABTF06207NA

Coffey Environments Pty Ltd (Coffey), August 2010d

Interim Groundwater Monitoring Event, Former Mobil Northcote Service Station (VO1003), Corner of St Georges Road and Arthurton Road, Northcote, Victoria, 19 August 2010. Reference ENVIABTF06207PA

Coffey Environments Pty Ltd (Coffey), August 2010e

CUTEP Report, Former Mobil Northcote Service Station (VO1003), Corner of St Georges Road and Arthurton Road, Northcote,3070 , 23 August 2010. Reference ENVIABTF06207KA

Note that the reports listed above are the key documents relating to site assessment, remediation and validation. The list does not include drafts of these reports and various scopes of work that the Auditor reviewed during this audit. Copies of the site assessment reports are included in Appendix F (on CD).


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4 Site Description

4.1 Site Location The site is located at 137 St Georges Road, Northcote (corner Arthurton Road), located approximately 6 km north of the Melbourne Central Business District (refer Figure 1). The site is located within the Darebin City Council municipal area. The Map Grid Australia (MGA) coordinates of the site are Easting 323042 and Northing 5817952 (Zone 55).

4.2 Land Characteristics The site area is an approximately rectangular shaped block with an area of 2015 square metres (0.20 hectares). The Arthurton Road frontage has a length of approximately 36 m and the St Georges Road frontage is approximately 53 m (Figure 2).

All site infrastructure, including buildings and petroleum related site equipment, was removed between 2003 and 2010. The site is currently vacant. Figure 2 illustrates the former site features present prior to infrastructure removal and remediation.

4.3 Property Description

4.3.1 Certificates of Title The Audit site is located at 137 St Georges Road, Northcote, 3070 (corner Arthurton Road) and is described as Land in Plan of Consolidation 100143, Volume 8836, Folio 772, Parish of Jika Jika, County of Bourke. A copy of the Certificate of Title and a Title Plan is provided in Appendix B. The title area (which is the site area subject to this audit) extends beyond the former service station area to St Georges Road along the eastern boundary and to Arthurton Road along the north eastern boundary (refer to Figure 2). The Auditor understands that the intersection was widened some time ago by VicRoads and the service station area was reduced, however, the title was not rectified. Plate 1 illustrates the widening of St Georges Road in the vicinity of the site compared to the properties to the south of Auburn Avenue.

4.3.2 Land Use Zone Under the provisions of the Darebin City Council Planning Scheme, the site is located within a Residential 1 Zone (R1Z). The site is subject to a Development Contributions Plan Overlay and a Special Building Overlay. Copies of the City of Darebin planning scheme and overlays are provided in Appendix C.

The purpose of the Darebin City Council R1Z is to:

• implement the State Planning Policy Framework and the Local Planning Policy Framework, including the Municipal Strategic Statement and local planning policies;

• provide for residential development at a range of densities with a variety of dwellings to meet the housing needs of all households;

• encourage residential development that respects neighbourhood character; and • in appropriate locations, to allow educational, recreational, religious, community and a limited range

of other non-residential uses to serve local community needs.


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The following land uses are prohibited within RZ1;

• amusement parlour; • animal boarding; • animal training; • brothel; • cinema based entertainment facility; • extractive industry; • horse stables; • industry (other than car wash); • intensive animal husbandry; • motor racing track; • nightclub; • office (other than medical centre); • retail premises (other than community market, convenience shop, food and drink premises and

plant nursery); • saleyard; • transport terminal; and • warehouse (other than store).

The site is overlain by a Development Contributions Plan Overlay (DCPO) and a Special Building Overlay (SBO).

The Development Contributions Plan Overlay is to identify areas which require the preparation of a development contributions plan for the purpose of levying contributions for the provision of works, services and facilities before development can commence.

The purpose of the Special Building Overlay is to:

• identify land in urban areas liable to inundation by overland flows from the urban drainage system as determined by, or in consultation with, the floodplain management authority;

• ensure that development maintains the free passage and temporary storage of floodwaters, minimises flood damage, is compatible with the flood hazard and local drainage conditions and will not cause any significant rise in flood level or flow velocity; and

• protect water quality in accordance with the provisions of relevant State Environment Protection Policies, particularly in accordance with Clauses 33 and 35 of the State Environment Protection Policy (Waters of Victoria).

4.4 Proposed Use of the Site The site owner, Mobil Oil Australia Limited, proposes to divest the site for use consistent with its land use zone (ie. residential – R1Z). The proposed use of the site is unknown, however it is assumed to be residential.


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4.5 Neighbouring Land Uses Land uses surrounding the site at the time of this Audit are summarised in Table 4-1 below

Table 4-1 Surrounding Land Uses

Direction Land Use

North Arthurton Road and commercial/residential East St Georges Road and residential South Auburn Avenue and residential West Laneway and residential

These neighbouring land uses were documented by, and confirmed by the Auditor during site inspections.

Potentially sensitive areas and possible receptors located within 500m of the site include the following:

• Batman Park, located approximately 100m to the northeast; • Greek Orthodox Monastery, located approximately 200m to the southeast; • Northcote High School, located approximately 500m to the south; • Merri park, located approximately 400m to the south; and • Croxton & Baltara Special Schools, located approximately 400m to the northwest.

4.6 Topography, Stormwater Runoff and Natural Watercourses The site is relatively flat, with a surface elevation of approximately 38 m AHD (based on elevations of groundwater bores at the site), grading slightly to the south. The western side of the site has been built up to provide a relatively flat surface. Plate 2 illustrates the retaining wall along the western site boundary along the laneway.

Historically, the majority of the site was covered with buildings or had a sealed surface of concrete. Garden beds were present in some areas of the site (Coffey, July 2006).

As at 15 July 2010 (final site inspection), the site was relatively flat and covered with compacted non-descript crushed rock (NDCR) (refer to Plate 3).

Based on the relatively flat topography, surface water falling on the site is likely to remain onsite and seep into the NDCR surface.

There are no natural watercourses at or in the immediate vicinity of the site. Merri Creek flows northwest to southeast through Thornbury and Brunswick East, with the creek flowing closest to the subject site approximately 550 metres southwest of the site (refer to Figure 1).

4.7 Regional Geology and Hydrogeology According to the 1:31,680 scale (SJ 55-5) geological map of Melbourne and Suburbs (1959), the geology of Northcote and the surrounding area predominantly consists of Tertiary aged Brighton Group sediments and the Silurian aged Dargile Formation sediments (mudstones, siltstones and sandstones), with some overlying Quaternary aged alluvium and Quaternary aged Newer Volcanics (basalts) present in the area.


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The Dargile Formation forms the surface geology throughout the majority of the Northcote/Thornbury area and forms the basement rock and underlay the entire Melbourne area at depth.

The following description of the stratigraphy of the Northcote/Thornbury area is based on the Melbourne Geological Mapsheet (1959) and regional hydrogeological information is predominantly sourced from Leonard (1992) and Birch (2003).

Quaternary Alluvium (Qra) The Quaternary aged alluvium of the area is fluvial and consist of alluvium, gravel sand and silt (Melbourne Geological Mapsheet, 1959). The alluvium is located mainly along Merri Creek, and is present to the immediate west of the Audit site.

Newer Volcanics (Qvn) The Quaternary aged Newer Volcanics consist of tholeitic to alkaline basalts with minor ash and scoria (Melbourne Geological Mapsheet, 1959). The basalts comprise multiple lava flows that are derived from volcanic eruption centres to the north of Melbourne.

The Newer Volcanics weather to generate smectite clays at the land surface. These are notable for shrink and swell characteristics, as they are subjected to drying and wetting respectively. The weathering profile is seldom greater than 2 m thick. Where present, the Newer Volcanics disconformably overlie the Tertiary aged Brighton Group throughout the region.

Leonard (1992) indicates that the groundwater regime in the Newer Volcanics aquifer system is complex, comprising a number of superposed basalt flows that are often separated by clay and silt aquitards. The upper most aquifer is largely unconfined, whilst deeper aquifers are confined to semi-confined (Leonard, 1992). Groundwater occurs in the contact zone between flows and the in the fractures and joints (Leonard, 1992).

Bore yields for extraction purposes are considered to be poor and are generally less than 1 L/sec, however, can be up to 40 L/sec (Leonard, 1992). Hydraulic properties of the aquifer vary greatly due to the nature of the basalt. According to Leonard (1992), hydraulic conductivity varies generally between 1 and 6 m/day.

Groundwater salinity is also highly variable within the Newer Volcanics aquifer with total dissolved solids (TDS) values ranging from less than 100 to over 6,000 mg/L (Leonard, 1992).

Brighton Group (Tpb) The Brighton Group Sediments comprise non-marine sand, sandy clay, silt and gravel, which can range from 20m to 80m in thickness.

The Brighton Group aquifer is usually recharged by direct infiltration where the sediments outcrop or by vertical leakage from the overlying Newer Volcanics (where applicable) (Leonard, 1992). The Brighton Group may be locally confined by overlying new Volcanics flows to unconfined in other areas. The hydraulic conductivity of the aquifer varies, but is on average less than 0.5 m/day and transmissivity varies between 10 m2/day and 75 m2/day.

Bore yields from the Brighton Group in the northern suburbs of Melbourne are generally less than 0.6L/s and groundwater salinities range from 2,500 to 8,000mg/L TDS (Leonard, 1992).


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Dargile Formation (Sud) The Silurian aged Dargile Formation forms an undulating surface which is considered to be the basement beneath the Melbourne area. This Formation comprises laminated and bedded sandstone, minor interbedded siltstone and shale, with the sequences often ripple marked and cross bedded. The weathering product of this formation is clay and there are former clay pits indicated to be within the vicinity of the site (i.e. Sir Douglas Nicholls Reserve, north of the site).

The Silurian aquifer forms part of the “basement” aquifer complex which underlies Melbourne (Leonard 1992). The Silurian aquifer comprises sedimentary strata that generally have a low primary porosity and permeability. Subsequently, groundwater entry and flow is dependant on the intersection of water bearing fractures in the bedrock. The hydraulic conductivity of this aquifer varies, depending upon the degree of fracturing and is stated to range from 0.02 m/d to 1 m/d (Leonard, 1992).

Groundwater salinity in the aquifer is extremely variable, ranging from 94 to 2,769 mg/L TDS (Leonard, 1992).

The closest surface water body is the Merri Creek, located approximately 550 m southwest of the site (Figure 1). Regional groundwater flow in this aquifer is likely to be in a south to south west direction towards Port Phillip Bay.

4.8 Site Geology and Hydrogeology The assessment of geological and hydrogeological conditions at and around the site is based on investigations undertaken by Coffey (2008 to 2010) and ITE (2004).

The specific geology identified at the site identified a surficial layer of fill material. This was underlain by basaltic soils (clay, silty clay and sandy clay) in the northern portion of the site to approximately 4 to 5 m bgs, and residual sandy clay soil overlying siltstone bedrock (ie. Silurian Aged Dargile Formation) was identified in the central and southern portion of the site.

It is noted that due to the extensive remedial works undertaken at the site, the onsite basaltic clays in the northern portion of the site were predominantly removed during various phases of excavation works and the site was backfilled with non-descript crushed rock (NDCR).

Borelogs are included as Appendix D.

The following table is a generalised geological profile beneath the site based on Coffey (2008a, 2008c and 2009c).

Table 4-2 Generalised Geological Profile

Approximate Depth (mbgl)

Lithology Description

0 – 3.5 Fill FILL; Gravel, coarse grained, grey.

3.5 – 10.0 (limit of investigation) Siltstone Orange/red/brown, dry, moisture content increasing with depth


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Notable exceptions to this general profile include:

• Fine to medium grained grey/brown gravel fill was encountered to an approximate depth of 0.4 m at MW3 and MW4, located in Auburn Avenue to the south of the site (refer to Figure 2);

• Basaltic Clay was encountered to an approximate depth of 4 m at MW1 and 5 m at MW2, located in the footpath along Arthurton Road to the north of the site; and

• Clay backfill material was encountered at MW5 to a depth of approximately 3 m.

Dargile Formation (Sud) Four groundwater monitoring wells (MW1 – MW4) were initially drilled at the site in February 2008. An additional eleven groundwater wells were drilled at the site in July 2008. All wells at the site were completed within the weathered siltstone beneath the site (up to 14.5 mbgl). It is expected that the aquifer is confined to semi-confined beneath the site.

Depth to groundwater beneath the site ranged from 2.55 m bgs (MW3) to 5.76 m bgs (MW15) based on historical groundwater monitoring data reported since 2008. Based on the latest complete round of monitoring undertaken in November 2009, Coffey (February 2010a), describe the groundwater flow direction as towards the south in the southern portion of the site and towards the west in the northern portion of the site (refer to Figure 3). This is consistent with the expected regional groundwater flow direction to the south and southwest towards Merri Creek.

No site specific hydrogeological assessments were carried out on the monitoring well network to determine local characteristics of the aquifer at the site.

The TDS range within the Silurian aged aquifer at the site has historically ranged from 400 mg/L to over 10,000 mg/L. Monitoring wells MW2, MW3, MW4, MW13 and MW16 have consistently reported TDS values below 1,000 mg/L. These wells are located along the site boundary or off-site along the northern and southern footpaths in close proximity to water mains and/or storm water drains. The Auditor therefore considers it likely that the low TDS values observed in these wells are attributable to freshwater infiltration from these underground services and are not representative of background TDS concentrations. TDS values from the remaining wells ranged from 1,100 mg/L to over 6,000 mg/L in the most recent rounds of sampling in February and July 2010, therefore, groundwater at the site is considered to fall within Segment B of the State Environment Protection Policy (SEPP) Groundwaters of Victoria.

The “Department of Natural Resources and Environment, 1994, South Western Victoria Water Table Aquifer Map” places most of the Melbourne area north of the Yarra River within Segment C. Given the large range of TDS values recorded at the site, groundwater has been conservatively placed within Segment B.


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4.9 Groundwater Use in the Area URS undertook a groundwater database search from the State Wide Groundwater Database (Department of Sustainability and Environment) on 7 December 2010 and identified 59 groundwater bores within a 2 km radius of the site.

Results of the groundwater database search are presented in Appendix E. The bores are presented relative to the site on Figure 4. A review of the Groundwater Database search indicates the following:

• Of the 59 registered bores, 17 are for groundwater investigation purposes, nine for domestic and stock use, one for observation purposes and the remaining 32 are for unknown uses;

• Eight of the nine domestic and stock bores are located between 1.5 and 2.0 km from the site in a south east or south west direction. The ninth domestic and stock bore is located approximately 730 m to the south east of the site. Given the distance these bores are from the site and that they are not located directly down gradient of the site, in the Auditor’s opinion, these bores would not be affected by any groundwater contamination that may exist at the site;

• The depth of the registered bores are typically between 12 and 25 m bgs. One bore for an unknown use is installed at 150 m bgs;

The information provided by the Statewide Groundwater Database is consistent with the Auditor’s understanding that groundwater from the area is predominantly used for investigation purposes.


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5

5 Site History

5.1 Introduction Information on the historical land use at the site was obtained from the following report:

• Coffey Environments Pty Ltd, Phase 1 Environmental Site Assessment, Mobil Service Station Northcote (VO1003), Corner of St Georges Rd and Arthurton St, Northcote, Victoria, prepared for Mobil Oil Australia Pty Ltd, July 2006.

The Coffey report is attached as a CD in Appendix F.

5.2 Historical Overview Historical data was obtained by Coffey (2006) using various sources including:

• Historical Certificates of Title; • Historic aerial photographs; • Sands and McDougall’s Directories of Melbourne and Suburbs; • Royal Historical Society of Victoria; and • City of Darebin records search.

Historical Certificates of Title indicates the site was divided into smaller parcels and on separate titles. The site was originally divided in a north/south orientation, with Mr Joseph Bradshaw owning the western portion of the current site in 1893 prior to the transfer of the land to the Mayor Councillors and Citizens of the City of Northcote in 1917. The Mayor Councillors and Citizens of the City of Northcote also owned the remainder of the current site on separate titles dated 1914 and 1922. It is not known what the site was used for. However, surrounding properties were residential.

The site was subsequently subdivided into four lots in an east/west orientation and transferred to various private owners between 1926 and 1941 (land use unknown). The title for the northern portion of Lot 1 (bound by Arthurton Road to the north) listed “William Moses Young of the corner of Arthurton and St Georges Roads Northcote Service Station Proprietor” from December 1949. When Mr Young passed away in April 1952, the title was transferred to his widow prior to being transferred to Mr Neil Anderson Ludehope, “Garage Proprietor” in March 1953. This portion of Lot 1 was then immediately transferred to Mr Henry Oswald Allsop and Mr Charles Frederick Allsop, who also acquired the southern portion of Lot 1 in March 1953, prior to transfer of all of Lot 1 to the current owner, Mobil Oil, in 1968.

Lots 2, 3 and 4 were transferred to various private owners for unknown site uses prior to transfer to Mobil Oil in 1968 (Lots 2 and 3) and 1970 (Lot 4).

According to information obtained by Coffey from the Royal Historical Society of Victoria (July 2006), the site was listed as Young’s Service Station in 1934 and remained so until the 1950s. The next available listing in 1974 listed the site as Allsop’s Service Station.

Discussions between Coffey and the City of Darebin indicated that the site was subdivided into four allotments (listed as 137, 139, 143, and 151) in 1924 and occupied by residential housing in the early 1940s. Building material comprised brick veneer with sizes ranging from 13 to 27 squares. Mobil acquired the site in 1968 and proceeded demolishing existing houses, including the service station comprising a brick veneer shop located on allotment 151.


5 Site History

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An aerial photograph review undertaken by Coffey (July 2006) indicated that in 1956 the site appeared to be subdivided into four allotments comprising vacant land and residential development. The 1966 photograph indicates a buildings representative of a service station are present. By 1978, when Mobil Oil owned the site, the photograph clearly shows the site is paved and cleared of vegetation and a service area and two additional canopies are evident.

Coffey (2006) reviewed three historical Mobil site plans, dated 31 October 1967, 5 January 1968 and 1977. According to Coffey, the 1968 plan shows a proposed service station layout with four USTs. The location and number of USTs (five) changed from the October 1967 and January 1968 plans and according to Coffey, given the short period time between the two drawings, it was assumed that the 1968 plan identifies the original location of the site’s USTs (four located towards the southeast corner of the workshop and one north of the proposed sales building) rather than the physical relocation of the USTs. According to Coffey, the purpose of the 1977 plan appears to be for the conversion of the original service station to a self-service business. An additional two USTs were identified to the northeast of the sales building.

All known petroleum hydrocarbon infrastructure was removed in June 2003, with the exception of three USTs located in the northeast corner of the site and extending under the footpath at the intersection of St Georges and Arthurton Roads. These three USTs were removed in February 2010. Removed infrastructure included eleven USTs, dispensing pumps, fill points, fuel lines, triple interceptor trap (TIT), and a hoist pit.

A site plan showing the historic layout of the site (circa 1970’s) is included as Figure 2.

5.3 Potential Contaminants of Concern Based on historic activities at and around the site, potential contaminants of concern (PCoC) have been identified and summarised in Table 5-1 below:

Table 5-1 Potential Site Contaminants of Concern

Activity Potential Contaminants of Concern

Storage of unleaded and leaded petrol Total Petroleum Hydrocarbons (TPH) Benzene, Toluene, Ethylbenzene and Xylenes (BTEX) Methyl Tertiary-Butyl Ether (MTBE) Lead

Storage of diesel fuel TPH Polycyclic Aromatic Hydrocarbons (PAHs) Phenols

Automotive workshop TPH Volatile Halogenated Compounds (VHCs) Heavy metals

Imported fill Metals TPH PAHs


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6

6 Beneficial Uses and Environmental Quality Criteria

6.1 General In conducting an Environmental Audit, the Auditor must be satisfied that the environmental condition of the site is neither detrimental nor potentially detrimental to beneficial uses of the site.

Beneficial use means a use of the environment or any element or segment of the environment which is: • conducive to public benefit, welfare, safety, health or aesthetic enjoyment and which requires

protection from the effects of waste discharges, emissions or deposits or of the emission of noise; or

• declared to State Environment Protection Policy to be a beneficial use.

The site is the land and all other elements within the boundary of the parcel of land that is subject of the Environmental Audit.

An element of the environment is any of the principal constituent parts of the environment including land, water, atmosphere, vegetation, climate, sound, odour, aesthetics, fish and wildlife. The relevant elements for the audit site are considered to be the following;

• Land at the site; • Groundwater beneath the surface of the site and down-hydraulic gradient of the site; and • Surface waters receiving runoff from the site.

The selection of environmental quality criteria for a site by the Auditor is based on the consideration of any possible “beneficial use” that may be feasible, and is particularly focused on the existing and likely future uses of the site. This includes consideration of all likely “sensitive uses” (e.g. residential dwelling) and of the potential for ecological risks presented by any chemicals that may remain on the site, by reference to accepted Australian Environmental Investigation Thresholds.

Where a site is contaminated to a level that precludes the protection of a beneficial use, the Auditor will conclude that the site is detrimental or potentially detrimental to one or more beneficial uses. In this event, the Auditor will indicate the measures necessary to:

• clean up the site to a level where the contamination does not preclude protection of any beneficial use or the beneficial uses designated by the Auditor; or

• manage the site to a level where the contamination does not preclude protection of the beneficial uses designated by the Auditor.

6.2 Land As outlined in Section 4, the site is within a Residential 1 Zone (R1Z), which enables sensitive use. The proposed use of the land is unknown, however it is assumed to be residential.

The State Environment Protection Policy (SEPP) Prevention and Management of Contaminated Land (PMCL) provides a statutory framework for protecting people and the environment from the effects of contamination. In accordance with Table 1 of that SEPP, the potential land use (sensitive use) requires the following beneficial uses to be protected:

• Human health; • Maintenance of (modified and highly modified) ecosystems; • Production of food, flora, and fibre; • Buildings and structures; and • Aesthetics.



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Soil quality objectives for the beneficial uses of land are outlined in Table 2 of the SEPP (Prevention and Management of Contaminated Land).

The Auditor has compared the results of the site investigations (soil) with the soil quality criteria adopted for the purposes of this audit outlined in Table 1. These reflect the soil quality objectives of the SEPP (PMCL) and the adoption of appropriate criteria when no soil quality objectives are identified in the SEPP. The soil quality objectives of the SEPP (PCML) are the environmental and health investigation levels published in the National Environment Protection Measure (NEPM) ‘Assessment of site contamination’ (Schedule B1), December 1999.

6.2.1 Human Health The Auditor has adopted the following health investigation levels (HILs) from the NEPM ‘Assessment of site contamination’ (Schedule B1):

• NEPM A HILs - “Standard” residential with garden/accessible soil (with home grown produce contributing less than 10% of vegetable and fruit intake) (low density residential).

• NEPM D HILs - Residential with minimal opportunities for soil access (high density residential). • NEPM E HILs – Parks, recreational open space and playing fields. • NEPM F HILs - Commercial/industrial uses including shops, offices factories and industrial sites.

For analytes where there are no human health investigation levels published in the NEPM (e.g. TPH C6-C9, TPH C10-C36) the Auditor has adopted the following:

• USEPA Regional Screening Levels (RSL) (2010) In the absence of a defined Soil Quality Criteria in the NEPM (1999) for metals (antimony, barium, tin, and vanadium); BTEX (benzene, toluene, ethyl benzene and xylenes); chlorinated hydrocarbons (e.g. PCE, TCE); and solvents (acetone and formaldehyde), US EPA Regional Screening Levels (RSLs) (2010) for residential soil and industrial soil have been adopted as the criteria for low-density residential and industrial end-uses respectively. High Density Residential criteria have been derived for metals by applying four times the Low Density Residential criteria. This is based on the relative exposure duration to non volatile compounds of high density land use expected when compared to low density residential land use, consistent with the NEPM (1999). For volatiles, no relative exposure factor has been applied, and the residential RSLs retained for low-density and high-density end-uses. Public Open Space criteria have been derived by applying two times the low density residential criteria, consistent with the NEPM.

With respect to SLs, the US EPA User’s Guide (USEPA, 2010) notes that SLs are tools for evaluating and cleaning up contaminated sites. They are risk-based (carcinogenic and non-carcinogenic) concentrations that are intended to assist risk assessors and others in initial screening-level evaluations of environmental measurements. The SLs are generic, and calculated without site specific information.

• CCME Canada-wide Standards for Petroleum Hydrocarbons (PHC) in Soil (2008) As speciated TPH analysis (to enable comparison with the limited NEPM HILs) was not undertaken, the CCME (2008) have been adopted. These are considered relevant as, similar to the NEPM, they have been developed using a scientifically defensible risk-based approach. They are based on the assessment and management of risks posed to humans, plants, animals and environmental processes (e.g. migration of soil contamination to underlying groundwater) under four common uses of land – agricultural, residential/parkland, commercial and industrial.



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Toxicological values for the CCME (2008) hydrocarbon fractions incorporate the Total Petroleum Hydrocarbon Working Group (1999) approach of proportioning aliphatic / aromatic components of TPH into fractions with similar toxicological and environmental behavioural properties. The CCME (2008) further group these fractions into practical sub-fractions based upon hydrocarbon-chain length (see below); each practical sub-fraction then has a toxicological value determined. This is consistent with the NEPM (1999). The CCME standards assume conservative exposure durations for the land use scenarios anticipated.

It is noted that CCME (2008) specifies Tier 1 concentrations for hydrocarbon fractions that are slightly different than those typically analysed by Australian laboratories. That is, CCME (2008) specifies C6-C10, C10-C16, C16-C34, and C35+ while the Australian Laboratory Fractions are C6-C9, C10-C14, C15-C28, and C29-C36. However, the CCME (2008) ranges are considered to be generally representative of risk conditions posed by the corresponding Australian laboratory TPH fractions, and are therefore considered to be appropriate screening criteria for the purpose of assessing site conditions.

The exposure scenarios as outlined in CCME (2008) may be directly applied to Australia for adoption for equivalent land use scenarios (with the exception of high density residential and public open space for which there are no CCME criteria). High Density Residential criteria have been derived by applying four times the Low Density Residential criteria except for volatiles (TPH C6 – C9) which are the same as for “standard” (i.e low) density residential. This is based on the relative exposure duration of high density land use expected when compared to low density residential land use, consistent with the NEPM (1999). Public Open Space criteria have been derived by applying two times the low density residential criteria, consistent with the NEPM.

• Victorian Occupational Health and Safety (Asbestos) Regulations (2003)

In the absence of a defined Soil Quality Criteria the NEPM (1999), Victorian Occupational Health and Safety (Asbestos) Regulations (2003) have been adopted for asbestos. Part 3 of the regulations (Prohibitions) ‘prohibit the use and reuse of asbestos containing materials (Regs 307 & 312(3)) unless it is soil from which asbestos has been removed and a visual inspection of the soil by a person indicates that there is no remaining asbestos containing material in the soil (Reg 301(3a) - General Exclusions)’. Effectively, the Auditor has adopted a ‘no visual evidence of asbestos’ criterion.

The adopted soil criteria applicable to the protection of human health are shown in the attached Table 1.

6.2.2 Maintenance of Ecosystems The Auditor has adopted the following ecological investigation levels (EILs) from the NEPM ‘Assessment of site contamination’ (schedule B1):

• NEPM - interim urban EILs – for the urban setting are based on considerations of phytotoxicity, ANZECC B levels, and soil survey data from urban residential properties in four Australian capital cities. For chromium, EILs are presented for chromium III and the more toxic chromium VI. For maintenance of ecosystems, it has been assumed that the chromium beneath the site comprises chromium III, and this value has been adopted as the screening criterion for total chromium. This is considered to be a reasonable assumption, as no anthropogenic sources of chromium contamination have been identified for the site, and naturally occurring chromium is composed almost exclusively of chromium III.



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For analytes where there are no EILs published in the NEPM the Auditor has adopted:

• ANZECC (1992) Environmental Investigation Levels

Environmental Investigation Levels from ANZECC (1992) have been adopted for metals where there is no NEPM EIL (tin).

• Canadian Council of Ministers of the Environment (CCME) Canada-wide Standards for Petroleum Hydrocarbons (PHC) in Soil (2008)

As described in Section 6.2.1, the CCME (2008) criteria are derived to protect multiple receptors (including human health and environmental receptors). The method of derivation is to separately derive criteria for multiple end-points, and select the most conservative as the overall criterion. Reference to the supporting technical document allows the value protective of environmental receptors to be identified. For the protection of modified ecosystems, the Auditor has adopted the most stringent of the guidelines identified to protect ecological receptors in CCME (2008) Environmental Quality Guidelines for TPH (C6-C9), (C10-C14), and (C15-C36).

• CCME Canadian Soil Quality Guidelines for the Protection of Environmental and Human Health (2007)

The CCME (2007) criteria are derived to protect multiple receptors (including human health and environmental receptors). The method of derivation is to separately derive criteria for multiple end-points, and select the most conservative as the overall criterion. Reference to the individual supporting technical documents for each contaminant allows the value protective of environmental receptors (the Environmental Quality Guideline, derived utilising toxicological data for vascular plants and invertebrates) to be identified. For the protection of modified ecosystems, the Auditor has adopted the CCME (2008) Environmental Quality Guidelines for BTEX compounds (benzene, toluene, ethyl benzene, and total xylenes).

• USEPA Ecological Screening Levels for Soil PAHs (2007) (Interim Final)

The USEPA Ecological Screening Levels (Eco-SSLs) are concentrations of contaminants in soil that are protective of ecological receptors that commonly come into contact with and/or consume biota that live in or on soil. Eco-SSLs are derived separately for four groups of ecological receptors: plants, soil invertebrates, birds, and mammals. The criterion for the protection of soil invertebrates has been adopted for Total PAHs. Separate criteria are presented for low-molecular weight (less toxic) and high-molecular weight (more toxic) PAHs; the criterion for high-molecular weight PAHs has conservatively been selected.

6.2.3 Production of Food, Flora and Fibre For the protection of beneficial use of food flora and fibre the Auditor has adopted the same criteria as for the beneficial use maintenance of ecosystems.

6.2.4 Buildings and Structures According to the SEPP (PMCL), contamination must not cause the land to be corrosive to, or adversely affect the integrity of structures or building materials.



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The exposure classifications for concrete piles and steel piles outlined in Australian Standard 2159-2009 “Piling-Design and Installation” (AS2159) have been considered during this Audit. AS2159 provides exposure conditions for sulphates (expressed as SO4), chlorides, and pH in order to assess soil conditions under an exposure classification. The criterion for sulphate from this standard has also been adopted into the NEPM as the EIL, where it is noted to be for the protection of buildings and structures.

6.2.5 Aesthetics According to the SEPP (PMCL), contamination must not cause the land to be offensive to the senses of human beings. Although this is a subjective parameter, aesthetic issues relating to the site may include discoloured soil (stained from spills, containing coloured waste, for example oil or carbon black), malodorous soils, abnormal consistency or soil containing waste (such as foundry slag, ash, bricks and concrete).

6.3 Groundwater The TDS of the regional groundwater at the site has historically ranged from 400 mg/L to over 10,000 mg/L. A number of site excavations were left open for long periods of time and the site is now covered with porous fill material, therefore, it is likely localised rainwater infiltration has lowered the groundwater TDS in some wells. It is also noted that monitoring wells MW2, MW3, MW4, MW13 and MW16 have consistently reported TDS values below 1,000 mg/L (refer to Table 5 from Coffey, 2010d). These wells are located along the site boundary or off-site along the northern and southern footpaths in close proximity to water mains and/or storm water drains. The Auditor therefore considers it likely that the low TDS values observed in these wells are attributable to freshwater infiltration from these underground services and are not representative of background TDS concentrations.

TDS values from the remaining wells range from 1,100 mg/L to over 6,000 mg/L in the most recent rounds of sampling in February and July 2010. The Victorian Groundwater Beneficial Use Map classifies groundwater in the area of the site as within Segment C. Based on the range of background TDS values observed, the regional groundwater at the site is considered to be within Segment B in accordance with the State Environment Protection Policy (Groundwaters of Victoria), 1997.

The beneficial uses of groundwater to be protected for Segments B are:

• Maintenance of ecosystems; • Potable mineral water supply; • Agriculture, parks and gardens; • Stock watering; • Industrial water use; • Primary contact recreation (e.g. bathing, swimming); and • Buildings and structures.

The Auditor notes the groundwater at and around the site is not mineral water as defined in Clause 4 of the SEPP (GoV) and therefore the beneficial use “potable mineral water” is not discussed further in this Audit report.

The levels of groundwater quality required to protect beneficial uses are specified by the groundwater quality indicators and objectives in Table 2 of the SEPP (GoV) (1997).



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The Auditor has compared the groundwater results of the site investigations with the groundwater quality criteria adopted for the purposes of this Audit. These reflect the groundwater quality objectives of the SEPP (Groundwater of Victoria) (see Table 6-1) and the adoption of appropriate criteria where there are no SEPP objectives (e.g. TPH C10-C36). The groundwater quality criteria adopted for the purposes of this audit are provided in Table 2 (attached).

6.3.1 Maintenance of Ecosystems Unlike other beneficial uses, the groundwater quality objectives (GWQOs) for maintenance of ecosystems apply at the point of discharge to surface water, prior to dilution and mixing with the receiving surface water.

The site is situated in the Waters of the Yarra Catchment (SEPP, Waters of Victoria, 1997-Schedule F7). The segment of the Yarra Catchment is the Rural Western Waterways Segment. According to the SEPP (as varied in 2003), the ANZECC 2000 protection of aquatic ecosystems, 95% protection are the GWQOs for this beneficial use and are provided in Table 2. Where only low-reliability trigger values are available in the ANZECC 2000 guidelines, these have been adopted.

As there are no GWQOs for Total Petroleum Hydrocarbons (TPH) in groundwater, the Tasmanian groundwater guideline value (Department of Primary Industries, September 2002) has been adopted for TPH C10-C36 (600 ug/L). This value is adopted from guideline criteria developed by the Netherlands Ministry of Housing for “mineral oil”.

There are also no GWQOs for MTBE in groundwater. The Auditor has therefore referred to the US EPA “Aquatic Life Criteria for MTBE” Fact Sheet (March 2006) and adopted the guideline value of 51,000 ug/L (51 mg/L).

ANZECC issued errata slip for the Fresh and Marine Water Quality Guidelines (ANZECC 2000) wich states that the nitrate trigger values should be deleted and replaced with “under review”. A memorandum was issued by Chris Hickey of the National Institute of Water and Atmospheric Research (2002) clarifying the guideline values for nitrate presented in ANZECC 2000. The memorandum presented recalculated guidelines following review of the toxicological data. These recalculated guidelines (including 7.2mg/L for Nitrate – N for 95% protection of Maintenance of Ecosystems) have been adopted as the criteria for nitrate and nitrate as N. The errata slip and memorandum is presented in Appendix I.

The closest surface water body to the site is Merri Creek located approximately 550 m west of the site.

6.3.2 Agriculture, Parks and Gardens The Auditor has adopted the following GWQOs for this beneficial use:

• Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC) 2000. Chapter 4: Primary Industries – Water quality for irrigation and general water use.

These guidelines do not include criteria for organic compounds (other than pesticides).

Although there are no published objectives for petroleum hydrocarbons for the beneficial use ‘agriculture, parks and gardens’, concentrations of BTEX compounds in excess of 20 to 50 µg/L are expected to result in a ‘petrol smell’ that could result in groundwater not being used for that purpose if it were otherwise suitable for that use.



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As there are no Australian GWQOs for MTBE in groundwater, the Auditor has adopted the low end of the US EPA guideline range of 20 to 40 ug/L (US EPA Fact Sheet: Methyl Tertiary-Butyl Ether (MtBE) (December 1997)). This range is based on potential aesthetic impacts (taste and odour) in drinking water rather than health impacts and has been conservatively applied to the beneficial use “agriculture, parks and gardens” if using impacted groundwater to spray garden from a hand held hose.

As there are no GWQOs for Total Petroleum Hydrocarbons (TPH) in groundwater, the Tasmanian groundwater guideline value (Department of Primary Industries, September 2002) has been adopted for TPH C10-C36 (600 ug/L). This value is adopted from guideline criteria developed by the Netherlands Ministry of Housing for “mineral oil”.

The adopted groundwater quality criteria for the agriculture, parks and gardens beneficial use are provided in Table 2.

6.3.3 Stockwatering The Auditor has adopted the following GWQOs for this beneficial use:

• Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC) 2000. Chapter 4: Primary Industries – Livestock drinking water quality.

Where there are no stockwatering specific objectives in ANZECC (2000) (e.g. organic toxicants), the document recommends drinking water guidelines for human health be adopted (National Medical Health and Research Council (NHMRC, 2004).

Where there are no criteria in NHMRC (2004), the Auditor has adopted the following:

• The USEPA Regional Screening Levels (tap water) for various chlorinated hydrocarbons (including TCE and chlorobenzenes); various PAHs; various metals; and various PCBs;

• The World Health Organisation Drinking Water Guidelines (2008) for pentachlorophenol and endrin;

• The Tasmanian groundwater guideline value (Department of Primary Industries, September 2002) has been adopted for TPH C10-C36 (600 ug/L). This value is adopted from guideline criteria developed by the Netherlands Ministry of Housing for “mineral oil”.

The adopted groundwater quality criteria for the stockwatering beneficial use are provided in Table 2.

6.3.4 Industrial Water Use The Auditor has adopted the following GWQOs for this beneficial use:

• Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC) 1992. Chapter 6: Industrial Water Quality.

The ANZECC (1992) guideline states that “water quality may affect the product by decaying (biological action), staining, corrosion, chemical reaction or contamination. It may affect the equipment by corrosion, scale formation or erosion, and plant efficiently by sludge formation, scale formation, foaming or organic growth.”

Based on background TDS, industrial water use of local groundwater would be restricted to “once-through cooling systems”. Therefore, the criteria of Table 6.3 of ANZECC (1992) have been adopted where available and are provided in Table 2.



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6.3.5 Primary Contact Recreation The Auditor has considered the GWQOs outlined in ANZECC (2000), Chapter 5: Guidelines for Recreational Water Quality and Aesthetics for the beneficial use of primary contact recreation. However, in ANZECC 2000 it is stated that until new recreational guidelines are to be developed; in the interim ANZECC 1992 should be applied (reproduced in ANZECC 2000). Subsequently, NHMRC developed the Guidelines for Managing Risks in Recreational Water 2008 (NHMRC 2008). This document references the NHMRC (2004) Australian Drinking Water Guidelines (ADWG, 2004) as a guide. NHMRC 2008 states that to account for percentage of daily intake from recreational waters, the drinking water guidelines provided can be modified by a factor of 10 to provide screening levels for chemicals. Therefore the Auditor has adopted the objectives and approach presented in NHMRC 2008. Drinking water guidelines presented in ADWG, 2004 indicate whether they are derived for aesthetic reasons or protection of health. This distinction between the derivation of the guidelines is re-presented in Table 2 for information.

For phenolics, a value is available in ANZECC (2000) but not in NHMRC (2008); this has been adopted as the criterion for phenolics. Where there are no recreation specific objectives in NHMRC (2008) or ANZECC (2000) the Auditor has adopted the following:

• The US EPA RSLs for tap water (2010) for various chlorinated hydrocarbons (including TCE and chlorobenzenes); various PAHs; various metals; and various PCBs. These drinking water values have been multiplied by 10 in accordance with NHMRC, 2008;

• The World Health Organisation Drinking Water Guidelines (2008) for pentachlorophenol and endrin. These drinking water values have been multiplied by 10 in accordance with NHMRC, 2008;

• The Tasmanian groundwater guideline value (Department of Primary Industries, September 2002) has been adopted for TPH C10-C36 (600 ug/L);

• The low-end of the US EPA guideline range of 20 to 40 ug/L (US EPA Fact Sheet: Methyl Tertiary-Butyl Ether (MtBE) (December 1997)). This range is based on potential aesthetic impacts (taste and odour) in drinking water rather than health impacts and has been conservatively applied to the beneficial use “primary contact recreation” if incidental ingestion in pools/spas filled with groundwater occurs; and

• Oil and petroleum should not be noticeable as a visible film on the water nor should they be detectable by odour (ANZECC 2000, Chapter 5).

The adopted groundwater quality criteria for the primary contact recreation beneficial use are detailed in Table 2.

6.3.6 Buildings and Structures The Auditor has adopted exposure classifications for concrete piles and steel piles outlined in Australian Standard 2159-2009 “Piling-Design and Installation” (AS2159-2009) for the purposes of this Audit. AS2159-2009 provides exposure conditions for sulphate (expressed as SO4) pH, and chloride in water in order to assess soil conditions under an exposure classification.



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6.4 Surface Water The site is situated in the Waters of the Yarra Catchment (SEPP, Waters of Victoria, 1997-Schedule F7). The segment of the Yarra Catchment is the Rural Western Waterways Segment. The Water Quality Objectives for this Segment are based on the 95% protection for “slightly” or “moderately modified” aquatic ecosystems, ANZECC 2000.

The Auditor does not consider that the site will affect any surface waters near the site for the following reasons:

• The stormwater system on site has been disconnected;

• The land surface is relatively flat and therefore limited surface water run off is expected; and

• The closest surface water body, Merri Creek, flows northwest to southeast through Thornbury and Brunswick East, with the creek flowing closest to the site approximately 550 metres southwest of the site.


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7

7 Environmental Site Assessment

A number of site assessments have been conducted at the site, as listed in Table 3-2, Section 3.3. Copies of these reports are attached in the CD provided in Appendix F.

These are the only reports known to relate to the assessment of contamination at the site. A summary of each site assessment is provided in the following sections.

7.1 Environmental Site Assessment (Handex, 1998) Handex was engaged by Mobil Oil Australia to undertake an Environmental Site Assessment of the closed service station facility on the corner of St Georges Road and Arthurton Road, Northcote.

The objective of the assessment was to assess environmental conditions of the site (Handex, 1998) prior to divestment.

Handex conducted a desktop study of information provided by Mobil, and a soil and groundwater sampling program. At the time of the investigation, the site was closed; however, all infrastructure, with the exception of bowsers, were still present at the site.

The desktop study involved review of surrounding land use, description of known site infrastructure, and review of regional geology, hydrogeology and potential groundwater uses.

The soil and groundwater sampling program involved drilling nineteen soil bores in a grid pattern across the site to a maximum depth of approximately 3.7m bgs and installation of one groundwater well within siltstone to a depth of 8.5 m bgs. A sample of perched water was also collected from one of the soil bores.

The soil profile encountered was generally a 0.1 m layer of concrete underlain by a thin layer of fill to approximately 0.2m bgs. This was underlain by sandy and/or silty clay to the maximum soil bore depth of 3.7m bgs. Hydrocarbon odours were noted in eight of the soil bores and in the groundwater well during drilling by Handex.

According to Handex, the concentration of TPH C6-C9 in one soil sample exceeded the Victorian Sensitive Use Criteria at location NGP16-1.8 (160 mg/kg), located close to the northern site boundary. All other grid soil samples reported concentrations of TPH below the relevant criteria or the laboratory limits of reporting (LOR).

Handex also reported the following:

• The concentration of benzene exceeded the Victorian Sensitive Use Criteria at location NGP16-3.2 (1.8 mg/kg); and

• The concentration of toluene and ethylbenzene exceeded the Victorian Sensitive Use Criteria at location NGP16-1.8 (5.9 mg/kg and 12 mg/kg respectively). Concentrations of xylene and total BTEX (65 mg/kg and 84 mg/kg respectively) at this location exceeded the Victorian Sensitive Use Criteria and Dutch “C” Levels.

Handex reported that all concentrations of heavy metals were below the Victorian Sensitive Use Criteria and Dutch “C” Levels, with the exception of lead at the following locations:

• NGP3-0.4 (360 mg/kg) located close to the southeast corner of the site; and

• NGP11-0.3 (330 mg/kg) located close to the southwest corner of the site.

One groundwater well was installed close to the centre of the site (MW1) within siltstone, with the screen installed at approximately 6-8.5m bgs. The standing water level was approximately 2.5m bgs.



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Benzene was detected at near detection limit concentrations (3 μg/L) in groundwater from MW1. All other analytical results reported for groundwater sampled from MW1 were below the laboratory detection limits.

Perched water was encountered at soil location NGP14 at approximately 1.2 m bgs, located close to the northwest corner of the site. The perched water sample, NTW1 reported concentrations of TPH C6-C9 (1,900 μg/L), TPH C6-C36 (3,700 μg/L), benzene (16 μg/L), ethylbenzene (63 μg/L), and total BTEX (110 μg/L) above the Dutch “C” Levels.

Handex concluded that the site appeared to have been impacted by the hydrocarbons from the USTs and, in its current condition, the site was not suitable for the current Residential “C” Zoning.

7.2 Tank Excavation Assessment Report (ITE, 2004) ITE was engaged by Mobil Oil Australia to undertake a Tank Excavation Assessment (TEA) at the former Mobil service station on the corner of St Georges Road and Arthurton Road, Northcote.

The objectives of the TEA were to:

• Remove primary sources of hydrocarbon contamination at the site, including all petroleum storage and handling infrastructure;

• Obtain information on soil contamination in the vicinity of UST excavations and other underground fuel infrastructure; and

• Validate the soils in the immediate vicinity of the UST/fuel infrastructure excavations.

Eight USTs were removed during excavation works in June 2003 by Abard Engineering. ITE noted that no scratches or holes were observed in the four fibreglass tanks (T1, T2, T3 and T5) and that the product lines were in good condition. No visible leaks were noted by either ITE or Abard Engineering. The four steel tanks (T4, T6, T7 and T8) had been abandoned and slurry filled at an earlier date (unknown) and the steel was noted to be in good condition with no gross corrosion evident. ITE noted that they did not observe any product leaks from tanks and associated infrastructure during removal. Refer to Figure 6 for UST locations.

The following table provides a summary of the excavations that were completed on site.



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Table 7-1 Summary of Site Excavations

Excavation Location

Excavation Size

(m x m)

Former Land Use

Soil Type Encountered

Range of PID

Readings (ppm)

Maximum Depth (m)

No. Validation Samples

A 9.5 x 16.3 USTs T1, T2 and T3

GRAVEL, pea gravel fill over natural silty clay

8.7 – 60.3 4.3 16 primary samples, 2 duplicates, 2 triplicates

B 5 x 5 UST T4, base of kerosene bowser

Backfill SAND, over natural silty clay

7.9 – 132 3.0 6 primary samples

C 1 x 10 Hoist and waste oil line


9.9 – 14.9 2.1 3 primary samples

D 10 x 12 USTs T5, T6, T7 and T8


21.9 – 1763 4.2 17 primary samples, 1 duplicate, 1 triplicate

Excavation E consists of Trenches A to E, the former locations of the bower islands and product lines Trench A 2.5 x 8 Bowser island

and tank lines GRAVEL/SAND fill over natural silty clay


Trench B 2.3 x 8 Bowser island and tank lines

GRAVEL/SAND fill over natural silty clay


Trench C 2.1 x 8 Bowser island and tank lines

GRAVEL/SAND fill over natural silty clay


Trench D 1 x 19 Product line GRAVEL/SAND fill over natural silty clay


Trench E 0.7 x 3 Waste oil line GRAVEL/SAND fill over natural silty clay

25.3 0.7 1 primary sample

According to ITE, six stockpiles were generated onsite during excavation works and sampled at a rate of 1 sample per 50 m3. The table below summarises the stockpiles that were generated onsite:



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Table 7-2 Summary of Soil Stockpiles

Stockpile Source Area Approx. Volume (m3)

No. Validation Samples

No. Field Screened Samples with PID

Stockpile A Pea GRAVEL from Excavations A and B

100 1 primary sample 2 samples

Stockpile B Pea GRAVEL from Excavation A

150 2 primary samples, 1 duplicate, 1 triplicate

3 samples

Stockpile C Pea GRAVEL from Excavation A

250 2 primary samples 5 samples

Stockpile D Backfill SAND from Excavation C

50 1 primary sample 1 sample

Stockpile E Pea GRAVEL from Excavation A

100 1 primary sample 2 samples

Stockpile F Backfill SAND, silty clay and slurry material from abandoned tanks from Excavation D and E

500 5 primary samples, 1 duplicate, 1 triplicate

10 samples

ITE did not observe significant amounts of water accumulating in the excavations or trenches while they were onsite observing tank removals or conducting soil sampling. However, ITE noted that a telephone conversation with Abard Engineering alerted them to the fact that Abard had pumped and disposed of 35,400 L of water from the site. ITE was not informed of the water pumping and disposal activities and therefore no pit water samples were collected for analysis.

ITE adopted NEPM ‘A’ (1999), NSW EPA Service Station Guidelines (1994) and Dutch Intervention Levels (2000) as the validation criteria for the site. EPA Bulletin 448.1 Classification of Wastes (2004) was used to classify soil for potential offsite disposal.

According to ITE, fourteen samples reported elevated levels of contamination above the adopted investigation criteria. In summary:

• Excavation A had been validated;

• Excavations B, C and D require further excavation/validation works;

• Trenches C and E, and base of kerosene bowser required further excavation/validation works;

• Stockpiles A, B, C, D, and E indicated contaminant concentrations below NEPM ‘A’ values, however, soils from stockpiles B, C, and D were noted to be odorous and therefore not considered suitable for reuse onsite; and

• Stockpile F reported two samples in excess of the NEPM ‘A’ criteria and Table 2 of EPA Bulletin 448.1. ITE recommended this stockpile be segregated and resampled.

According to ITE, as of 17 June 2003, no stockpiled soil had been removed from site. Excavations were open and no imported fill material had been transported to the site. ITE recommended that stockpiles A and E could be reused onsite as backfill; however, stockpiles B, C, and D were noted as odourous and therefore not considered suitable for reuse due to aesthetic considerations. They also suggested that Stockpile F be segregated and resampled, then appropriate soil management undertaken for either onsite or offsite use.



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7.3 Phase 1 Environmental Site Assessment (Coffey, 2006) Coffey was engaged by Mobil Oil Australia to undertake a Phase 1 Environmental Site Assessment of the Northcote Mobil Service Station located on the Corner of St Geroges Rd and Arthurton Road, Northcote.

The objectives of the assessment were to:

• Identify the presence of any potentially contaminated areas of concern; • Determine likely contaminant types; • Evaluate possible routes of contaminant migration; and • Determine the environmental sensitivity of surrounding areas/properties.

The scope of work for the Coffey Phase 1 Assessment involved:

• Review of historical Mobil site plans; • Review of regional geology and hydrogeology; • A Dangerous Goods Records Search; • Review of current and historical certificates of title; • Review of the EPA Contaminated Sites Registry; • Historical information from the Royal Historical Society of Victoria; • Review of historical aerial photographs dating from 1956; • Discussions with City of Darebin regarding historical local council records; and • Review of previous environmental site investigations.

Coffey reported that the site was non-operational and the following infrastructure was removed during the Tank Excavation Assessment (TEA) in June 2003:

• Eight USTs; • Dispensing pumps; • Fill points; • Vehicle hoist; and • Associated fuel lines.

Coffey undertook a search of historical information relating to the site. Details of this search, including searches of historical Certificates of Title, Royal Historical Society of Victoria, aerial photographs, and discussions with Darebin City Council, are outlined in Section 5.2 above.

At the time of the Phase 1 report, according to Coffey, all excavations and trenches had been backfilled and there were no sightings of spoil onsite as at 15 March 2006.

According to Coffey, the regional geology underlying the site area was expected to comprise Quaternary Newer volcanics (basalt, light to dark grey in colour with minor interbedded silty sand and baked soils) and the Silurian Dargile Formation (sandstone, siltstone, minor shaly siltstone). Previous investigations indicated the site was predominantly underlain by basalt from the Newer Volcanics; however, siltstone from the Dargile Formation was present in the south-eastern and south-western corners of the site. According to Coffey, previous investigations by Handex identified a perched aquifer approximately 1.2-2.5 m bgs at the base of the fill and unconsolidated sediments. It was unknown whether the perched aquifer was continuous offsite. The regional aquifer exists at approximately 7-10 m bgs, however, due to insufficient data, it was unknown if the depth to groundwater onsite is consistent with the regional groundwater level.



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A site conceptual model (SCM) generated by Coffey identified the potential impact from the former USTs and the potential for contamination to migrate offsite. Identified potential contaminants of concern from the hydrocarbon sources included TPH, BTEX, lead, PAHs, phenols, waste oil, VHCs, and metals.

The results of the Phase 1 ESA indicated that:

• The site has been operating as a service station for approximately 72 years; • The site was largely surrounded by residential properties and is currently zoned as Residential 1

(R1Z) under the Darebin Planning Scheme; • The site is not listed on, or in the vicinity of, a site listed on the EPA Priority Sites Register as of

February 2006; and • The site does not currently hold a license to Possess Dangerous Goods.

7.4 Inspection and Evaluation of Hazardous Materials (EnviroProtect, 2006)

EnviroProtect were commissioned by JFTA Pty Ltd to conduct a hazardous materials assessment of the Mobil service station located at 137-151 St. Georges Road, Northcote in December 2006.

The objectives of the hazardous materials assessment were to: assess the premises for the presence of any form of hazardous materials, identify the location, type and condition of the hazardous materials, and provide appropriate recommendations to ensure that the risk of exposure from the hazardous materials is controlled and prevented.

The principal items investigated during the hazardous materials assessment included asbestos, synthetic mineral fibre, lead paints, polychlorinated biphenyls (PCB), chemicals, and radiation contained within the onsite building.

The assessment involved visual observations and the collection and analysis of suspected hazardous materials. It did not include an environmental assessment for the identification of any underground contamination.

Materials identified as containing asbestos fibres during the survey were: asbestos cement products as fibrous cement sheeting and asbestos cement debris as asbestos cement sheeting debris.

Materials identified as containing hazardous materials during the survey were: synthetic mineral fibre in the form of air duct insulation, pipe lagging and general insulation, and various chemicals.

7.5 Further Tank Excavation Assessment (Coffey, 2007) Coffey (formerly ITE) was engaged by Mobil Oil Australia to undertake a further Tank Excavation Assessment (TEA) of the closed service station facility on the corner of St Georges Road and Arthurton Road, Northcote.

Tank excavation and soil validation works were conducted by Abard Engineering and IT Environmental (ITE) in June 2003 and reported in ITE’s Tank Excavation Assessment Report (2004). However, heavy rainfall in late 2003 affected excavations and stockpiles onsite necessitating further assessment at the site.



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The objectives of the further TEA were to:

• Validate soils in the immediate vicinity of Excavations A, B, C and D; Trenches C and E; soil sample location SS01; hoist pit and TIT;

• Re-sample eight existing stockpiles remaining onsite from the previous TEA work. Heavy rain in December 2003 redistributed stockpiled material around the site and into existing excavations, therefore re-sampling of stockpiled material and the excavations was required; and

• Obtain necessary approvals for disposal of contaminated soil/waste.

The scope of works included:

• Removal of the Triple Interceptor Trap (TIT); • Stockpile characterisation and offsite disposal; • Excavation validation; and • Importation of validated fill material for backfilling.

Large quantities of water were removed from open tank pits and excavations during site works after several heavy rainfall events. According to Coffey, a total of 185,300 L of water was pumped out and classified as aqueous hydrocarbon waste and disposed offsite by EPA licensed waste disposal contractors.

According to Coffey, a total of 22 stockpiles were created onsite. The total volume of excavated material was estimated to be 2,120 m3. A total of 63 primary stockpile samples were collected. Approximately 586 m3 of stockpiled soil reported analytical results below adopted assessment criteria, was noted to be free from residual hydrocarbon odour and/or staining and was assessed to be suitable for reuse as backfill material. The remaining 1533 m3 of stockpiled soil was assessed to be either above the adopted assessment criteria or contained hydrocarbon odour or staining. These stockpiles were classified according to EPA Bulletin 448.1 as follows:

• 1080 m3 as Fill Material (disposed offsite as Contaminated Soil (Low Level) due to presence of staining and/or odour);

• 385 m3 as Contaminated Soil (Low Level); and • 8 m3 as Contaminated Soil.

Coffey noted that at the time of reporting, all soil had been disposed offsite to an EPA licensed landfill with the exception of the 8 m3 contaminated soil, which remained onsite.

According to Coffey, 71 primary samples were collected from Excavations A, B, D, and Trenches A and D during the TEA and analysed for petroleum hydrocarbon impact. Sample density was in accordance with applicable regulatory guidelines, with the exception of the TIT and hoist pit (due to their proximity to the onsite building it wasn’t practical to excavate further to remove impacted soil and fully validate these locations), and the northern and western walls of Excavation D (due to inadequate sampling depth and number of samples submitted for analysis). As these areas were not sufficiently validated, further works would be necessary to validate these locations. Excavation extents and validation sample locations are illustrated on Figures 7a to 7d.

Coffey reported that the following excavation samples exceeded the adopted investigation criteria:

• TA-B2 (Trench ‘A’ located towards the central eastern portion of the site) exceeded the TPH C6-C9 investigation criteria;

• EXB-NW1 (Excavation ‘B’ located in the central northern portion of the site) and TA-NW exceeded the TPH C10-C36 investigation criteria;



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• TA-NW5 and TA-NW6 exceeded the benzene investigation criteria; • TA-NW6 exceeded the ethylbenzene investigation criteria; and • EXB-S, EXB-N and TA-N2 exceeded the benzo(a)pyrene investigation criteria.

Coffey noted that at the time of excavation works, it was understood that the potential future use of the site was for on-going general non-sensitive commercial use. A Tier 1 risk assessment was undertaken to assess risks to users of the site under a commercial land use. According to Coffey, the reported validation sample concentrations were deemed not to pose a risk in a commercial indoor air scenario. However, the benzene concentration of 8.6 mg/kg identified in soil sample TA-NW6 exceeds the Tier 1 risk assessment for maintenance/excavation workers. Coffey noted that if the site were to be divested for a more sensitive use, further clean-up works and/or a Tier 2 risk assessment may be required to accurately assess contamination levels and impact to maintenance/excavation workers (the Auditor notes that soil relating to sample location TA-NW6 was subsequently excavated and removed from the site).

According to Coffey, a total of 2864.66 tonnes of 40mm non-descriptive crushed rock (NDCR) was imported to site for backfilling of excavations during the 2005 works. The NDCR was validated prior to being imported and the results did not exceed the NEPM ‘A’ guidelines.

7.6 Phase 2 Environmental Site Assessment (Coffey, July 2008a) Coffey was engaged by Mobil Oil Australia to undertake a Phase 2 Environmental Site Assessment at the former Mobil service station located at the corner of St Georges and Arthurton Roads, Northcote.

Coffey noted that this was a preliminary offsite assessment to identify potential offsite soil and groundwater impact and to determine groundwater flow direction. At the time of writing the report, Coffey noted that onsite soil validation and infrastructure removal was underway and further onsite soil and groundwater assessment work would be conducted upon completion of soil excavation works.

The objectives of this Phase 2 ESA were to:

• Assess the nature, extent and sources of undissolved, dissolved and vapour phase petroleum hydrocarbon impacts of groundwater and soil (if any) at offsite locations;

• Assess the potential influence of site specific geological and hydrogeological conditions on the fate and transport of contaminants identified at the site;

• Identify potential risks (if any) that the contaminants may pose to human health and the environment;

• Use the data obtained from the assessment to propose appropriate corrective actions and/or options;

• Identify potential risk management options to address the encountered hydrocarbons.

The scope of works involved drilling, soil sampling, installation and groundwater sampling of four offsite groundwater monitoring wells (MW1 – MW4). MW1 and MW2 are located north of the site along Arthurton Road, and MW3 and MW4 are located south of the site along Auburn Avenue.

According to Coffey, the site specific geology encountered during drilling is described as follows:

• Coffey noted that there were no hydrocarbon odours or staining observed during drilling. Due to the siltstone geology, air hammer was the preferred method of drilling, which Coffey noted may have limited the opportunity to identify potential hydrocarbon odour or staining.



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• Groundwater wells were installed at depths of 8.0 m bgs (MW2 and MW3), 10.0 m bgs (MW4) and 14.5 m bgs (MW1) within the natural siltstone. According to Coffey, groundwater standing water levels (SWLs) measured between 3.17 (MW3) to 4.91 m below top of casing (m btoc) (MW4) within the siltstone underlying the site. Coffey concluded the siltstone aquifer was either confined or semi-confined. Based on interpreted groundwater contours, the inferred groundwater flow direction was to the south towards Merri Creek at a gradient of approximately 0.051. This flow direction is generally consistent with the anticipated regional groundwater flow direction.

According to Coffey, all soil analytical results were reported below the adopted criteria, with the exception of MW2-3.0, located to the north of the site, which contained a concentration of vanadium of 110 mg/kg. This concentration exceeded the maintenance of ecosystems Investigation Level (IL) of 50 mg/kg.

According to Coffey, all groundwater analytical results were reported below the adopted GWQOs with the exception of benzene (MW2 reported a concentration of 1.2 μg/L which exceeded the GWQO for primary contact recreation beneficial use (BU) of 1 μg/L) and various metals, including cadmium, chromium, cobalt, copper, lead, nickel and zinc, above the GWQO for the maintenance of ecosystems BU (nickel concentrations in some wells also exceeded the primary contact recreation BU).

Utility pit monitoring was undertaken by screening thirteen offsite pits for five minutes with a PID. No PID readings were recorded, and there was no visual or olfactory observations made, leading Coffey to conclude that there was no apparent impact of hydrocarbons within the monitored utility pits.

According to Coffey, soil analytical results did not preclude any of the relevant beneficial uses. Coffey noted that the concentration of vanadium identified in the soil was not considered to present a risk to soil ecosystems as the concentrations were considered to be representative of background levels and on-going soil validation work has identified similar concentrations of vanadium within the natural siltstone across the site. In regards to human health, all results were reported below the NEPM HIL ‘A’ levels. Coffey did not undertake an assessment as to whether soils are potentially corrosive to and likely to adversely affect the integrity of structures or building materials. Coffey noted that no deterioration of concrete footings was observed during on-going soil validation works on the site.

According to Coffey, impacted groundwater had not been delineated; however, groundwater conditions offsite were not considered likely to preclude any of the relevant protected beneficial uses. TPH C10-C28 concentrations were identified in MW2 (340 ug/L) and MW3 (160 ug/L), however, reported concentrations were below the adjusted adopted guidelines. Metal concentrations detected in groundwater were attributed by Coffey to background levels and not attributed to current or previous site activities.

Coffey concluded that further onsite assessment was required to identify potential contamination of groundwater and to determine whether potential petroleum hydrocarbon concentrations present in soil and groundwater are likely to pose an unacceptable health risk to proposed residential land use. According to Coffey, these results would also need to be confirmed with a quantitative Health Risk Assessment (HRA) to determine the potential health risks associated with possible residual hydrocarbon impact in groundwater.



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7.7 Soil Validation Assessment (Coffey, December 2008b) Coffey was engaged by Mobil Oil Australia to undertake a Soil Validation Assessment at the former Mobil service station located on the corner of St Georges Road and Arthurton Road, Northcote.

Tank excavation and soil validation works were undertaken in June 2003. Further excavation works were required and undertaken between August 2004 and July 2005, including re-sampling previously excavated tank pits and trenches, stockpile characterisation and offsite disposal and importation of validated fill material for backfilling.

The objectives of the soil validation assessment were to:

• Validate the top 1.0 m of soil across the site to ensure there was no residual contamination, remaining infrastructure, or aesthetic issues;

• Validate the soils in the immediate vicinity of previously excavated soil in Excavations B, C, and D, Trenches A and B, the former hoist pit and triple interceptor trap (TIT) (identified in the Further Tank Excavation Assessment (Coffey, 2007));

• Excavate test pits/trenches in the southern and south-eastern portion of the site where Handex (1998) previously identified lead contamination; and

• Obtain necessary approvals for the disposal of contaminated soil/waste and verify the contaminated material was disposed to a licensed facility.

Excavation locations are illustrated on Figure 8.

During this phase of works, three USTs were unearthed which had not previously been identified. These USTs were located in the northeast corner of the site and according to Coffey, extended beyond the site boundary underneath the adjoining footpath. According to Coffey, the tanks (T9 – T11) appeared to be of steel construction, in moderate condition and had previously been decommissioned and filled with water.

Upon consultation between Mobil, Coffey Environments, JFTA, the previous Auditor, VicRoads, and Darebin City Council, it was determined that the removal of the three additional USTs was neither safe nor practicable. Therefore, they were decommissioned (along with the surrounding area) with a 3% stabilising sand slurry.

According to Coffey, a total of 163 primary samples were collected from excavations and Coffey stated that the sample density was in accordance with Australian Standards AS4482.1 (1997) and AS4482.2 (2005) and NSW EPA (1994) Guidelines for Assessing Service Station Sites.

A total of 121 primary samples and 7 field duplicate samples and 7 field triplicate samples were collected from all stockpiles and analysed during the soil validation assessment.

According to Coffey, imported fill was sourced from High Quality Sales Bulla (clay material) and Boral Lysterfield Quarry (soft rock and NDCR) and sampled and analysed at a minimum rate of one sample per 100 m3 (total of 51 primary samples).

Coffey note that 41,000 L of water was removed from open excavations and the three additional USTs (2,000 L of oily water was pumped from the three USTs prior to decommissioning). The water was classified and disposed offsite by an EPA licensed waste disposal contractor.



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According to Coffey, excavation validation samples were assessed against the adopted guidelines, and where samples exceeded the criteria, excavations were extended until the samples collected at the excavation boundaries returned results below the adopted criteria and excavations were considered validated. Validation samples collected from all Excavations (A, B, C, and D, TIT, Trenches A and B) and Test Pits 1 and 2 reported analyte concentrations below the adopted guidelines, with the exception of four samples (TB-NW3, TB-EW24, TB-EW13 and TB-EW14).

Samples TB-NW3 and TB-EW24 were located along the northern site boundary (within the fenceline of Arthurton Road) and eastern site boundary (within the fenceline of St Georges Road) respectively (refer to Figure 8). TB-NW3 exceeded the adopted guidelines for TPH C6-C9 (114 mg/kg), ethylbenzene (5.4 mg/kg) and total xylene (26.6 mg/kg) while TB-EW24 exceeded the adopted guideline for TPH C6-C9 (69 mg/kg). Given the proximity of these sample locations to the site boundaries (as defined by the fence line), further excavation was not considered practicable. Trench B incorporating TB-NW3 was backfilled with compacted imported clay and the area incorporating TB-EW24 was backfilled with 3% stabilised slurry sand.

Samples TB-EW13 and TB-EW14, collected in the vicinity of the three additional USTs in the northeast corner of the site, returned analytical results above the adopted criteria. According to Coffey, soil in this area was removed up to the UST on the eastern boundary, however, it was not possible to excavate beyond the USTs. Coffey noted that sample TB-EW25, collected beneath the UST on the eastern boundary, reported analyte concentrations below the adopted criteria.

Coffey undertook a Tier 1 Qualitative Risk Assessment of residual TPH and BTEX contaminated soil (TB-NW3 and TB-EW24) against the New Zealand Government Ministry of Environment (1999) Guidelines for Assessing and Managing Petroleum Hydrocarbon Contaminated Sites. Coffey concluded that the samples along the eastern and northern site boundaries do not pose an unacceptable risk to site users, and a quantitative Tier 2 health risk assessment (HRA) would be required to confirm this assessment.

According to Coffey, prior to 1 July 2007, a total of approximately 1,848 m3 of stockpiled soil was disposed offsite in accordance with EPA Publication 448.1: 410 m3 as Contaminated Soil (Low Level) and 1,438 m3 as Fill Material (brick fill/stained/odorous). After 1 July 2007, approximately 2,840 m3 of stockpiled soil was disposed of off-site in accordance with EPA Publication 448.3: 120 m3 as Category B Contaminated Soil, 1,865 m3 as Category C Contaminated Soil and 855 m3 as Fill Material.

According to Coffey, a total of 5,692 m3 of material was imported to site, 5,232 m3 of which was NDCR, 384 m3 of clay and 76 m3 of 3% stabilised sand slurry. Validation samples were collected from the imported fill material. Several samples reported concentrations of vanadium, manganese, nickel, barium, or arsenic concentrations above the adopted NEPM EILs. Coffey attributed these exceedances to background concentrations of basalt NDCR sourced from the Melbourne area. Two samples reported concentrations of chromium and cobalt above the adopted NEPM HILs. Coffey undertook a review of these exceedances and found that the average concentrations of chromium and cobalt were below the adopted criteria and no samples exceeded 2.5 times the adopted criteria. Therefore, Coffey considered that the fill material was acceptable for use onsite.



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A selection of soil samples were analysed for pH and sulphate to assess the potential for soils at the site to corrode concrete structures. According to Coffey, the number of soil bores was consistent with AS 4482.1 Guide to Sampling and Investigation of Potentially Contaminated Soil. Soil samples were collected at 1.0m bgs and where natural soil was encountered. A total of twenty soil samples from eight soil bores were analysed for pH and sulphate. The soil pH results ranged from 7.3 to 10.1, with an average pH value of 8.7. Sulphate concentrations ranged 68 mg/kg to 1,880 mg/kg which are below the NEPM EIL guideline for sulphate (for protection of built structures) of 2,000 mg/kg. Coffey therefore considered that the concentration of sulphate in soil at the site is unlikely to preclude the beneficial use for buildings and structures. According to Australian Standard for Piling – Design and Installation (AS 2159), the concentrations of sulphate and the soil pH is likely to result in “non-aggressive” exposure of concrete piles, based on the most conservative measurements of 1,880 mg/kg of sulphate and a pH of 7.3.

7.8 Post Phase 2 Environmental Site Assessment (Coffey, December 2008c)

Coffey was engaged by Mobil Oil Australia to undertake a Post Phase 2 Environmental Site Assessment (PP2 ESA) at the former Mobil service station located at the corner of St Georges and Arthurton Roads, Northcote.

The purpose of this PP2 ESA was to assess whether previous activities conducted at the site have impacted upon the soil or groundwater and to evaluate if any identified impact may pose a threat to human health or the environment.

The objectives of this PP2 ESA were to:

• Assess the nature, extent and sources of undissolved and dissolved petroleum hydrocarbon impacts of groundwater and soil (if any) at onsite locations;

• Further assess the nature, extent and sources of undissolved and dissolved petroleum hydrocarbon impacts of groundwater at offsite locations;



• Use the data obtained from the assessment to propose appropriate corrective actions and options; and


This ESA was undertaken at this stage of the remediation works as excavation and backfilling of the site was completed and therefore, a detailed onsite groundwater assessment was able to be undertaken.

The scope of works involved drilling, soil sampling, installation and groundwater sampling of eleven onsite groundwater monitoring wells (MW5 – MW15), as well as groundwater sampling of the four existing offsite monitoring wells (MW1 – MW4).

Coffey also noted that the site contains fill (NDCR and clay) to a depth of 4m bgs where the former petroleum hydrocarbon infrastructure excavations were backfilled during site remediation works.



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Coffey noted that a slight hydrocarbon odour was observed during drilling of MW7 in the siltstone. No staining was noted in soil samples during the drilling of any of the soil bores/groundwater monitoring wells MW5 – MW15. Due to the siltstone geology, air hammer was the preferred method drilling, which Coffey noted may have limited the opportunity to identify potential hydrocarbon odour or staining. Refer to Appendix D for copies of the groundwater bore logs.

Groundwater wells were installed to a maximum depth of 10.0m bgs within the natural siltstone. Groundwater wells were gauged prior to sample collection using the low flow micro-purge technique. Groundwater standing water levels (SWLs) measured between 3.05 (MW12) to 5.41 m below top of casing (m btoc) (MW15). Based on the groundwater contour plan, the inferred groundwater flow direction is to the south towards Merri Creek.

TDS values ranged from 438 mg/L (MW3) to 9,920 mg/L (MW7). There was no PSH or hydrocarbon odour noted in any of the monitoring wells.

According to Coffey, all soil analytical results were reported below the adopted criteria, with the exception of MW8-6.0, located towards the central western portion of the site, which reported a concentration of nickel of 62 mg/kg. This concentration exceeded the maintenance of ecosystems IL of 60 mg/kg.

According to Coffey, soil analytical results did not present a risk to the relevant beneficial uses for the site. The concentration of nickel identified in MW8-6.0 was considered to be representative of background concentrations and on-going soil validation work has identified similar concentrations of nickel across the site. In regards to human health, all results were reported below the NEPM HIL ‘A’ levels. The soil pH and sulphate concentrations were reported at levels unlikely to preclude the beneficial use of buildings and structures, whereas a comparison with AS2159 indicates the soil pH and sulphate concentrations would likely result in a “moderate” exposure to concrete piles.

According to Coffey, all groundwater analytical results were reported below the adopted GWQOs with the following exceptions:

• MW7 reported a concentration of benzo(a)pyrene of 0.7 μg/L, exceeding the stock watering and primary contact recreation GWQOs of 0.01 μg/L;

• MW12 reported a concentration of total phenols of 2.1 μg/L, exceeding the stock watering GWQO of 2 μg/L;

• MW1, MW2, MW5 and MW11 reported concentrations of cadmium exceeding the maintenance of ecosystems GWQO of 0.2 μg/L;

• MW15 reported a concentration of chromium of 2 μg/L, exceeding the maintenance of ecosystems GWQO of 1 μg/L;

• MW1, MW3 and MW5 to MW15 reported concentrations of copper exceeding the maintenance of ecosystems GWQO of 1.4 μg/L;

• MW2 reported a concentration of iron of 620 μg/L, exceeding the maintenance of ecosystem GWQO of 300 μg/L;

• MW1, MW2, MW6 to MW11 and MW13 reported concentrations of nickel in excess of the maintenance of ecosystems, agriculture, parks and gardens and primary contact recreation GWQOs; and

• MW5 to MW15 reported concentrations of zinc exceeding the maintenance of ecosystems GWQO of 8 μg/L.



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According to Coffey, monitoring wells MW2, MW5, MW8 and MW9 contained groundwater concentrations of TPH C6-C9 above the laboratory LOR (20 ug/L), however, there were no concentrations of BTEX reported in these wells. Coffey enquired about this to the laboratory (ALS) and ALS advised that there was a peak in the VOC chromatograms, which could be attributed to the presence of MTBE. Coffey stated that this result would need to be confirmed by submitting fresh samples for the analysis of MTBE. Monitoring wells MW1 and MW5 to MW13 reported concentrations of TPH C10-C36 above the laboratory LOR (100 ug/L). Coffey suggested that a full semi-volatile organic compound scan would be required to identify the contributions of these results, or alternatively, further analysis using silica gel clean up of the laboratory extracts to determine if the compounds present are actually naturally occurring polar compounds.

Coffey concluded that contaminant concentrations in groundwater onsite and offsite are not considered likely to preclude any of the relevant protected beneficial uses. Coffey stated that metal concentrations detected in groundwater are regional and not attributed to current or previous site activities. Coffey also noted that these results would need to be confirmed with a qualitative Health Risk Assessment (HRA) to determine the potential health risks associated with possible residual hydrocarbon impact in groundwater.

7.9 Annual Groundwater Monitoring Event (Coffey, February 2009a) Coffey was engaged by Mobil Oil Australia to undertake a Groundwater Monitoring Event (GME) at the former Mobil Northcote Service Station located at the corner of St Georges and Arthurton Roads, Northcote.

The purpose of this GME was to assess whether previous activities conducted at the site have impacted the groundwater underlying the site, and to evaluate if any identified impact may pose a threat to human health or the environment.

The objectives of this GME were to:

• Assess the nature, extent and sources of undissolved, dissolved, and vapour phase petroleum hydrocarbon impacts of groundwater (if any) at all locations;



• Use the data obtained from the assessment to propose appropriate corrective actions or options; and


The scope of works involved gauging, sampling and analysis of all 15 existing groundwater monitoring wells (MW1 to MW15).

At the time of fieldwork (4, 5 and 8 September 2008), Coffey field personnel noted that all site excavations had been backfilled with NDCR and clay, the surface over the site consisted NDCR, and the site was secured by lockable cyclone fencing.



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According to Coffey, groundwater standing water levels (SWLs) measured between 2.57 (MW3) to 5.21 m below top of casing (m btoc) (MW15) and the inferred groundwater flow direction was generally south towards Merri Creek, however groundwater flow in the northern portion of the site had a slight westerly flow (also towards Merri Creek).

TDS concentrations ranged from 60 mg/L (MW2) to 10,400 mg/L (MW7) and the groundwater beneath the site was classified within Segment B of the Groundwater SEPP. There was no PSH or hydrocarbon odour noted in any of the monitoring wells.

According to Coffey, the concentrations of sulphate were higher than chloride in the majority of samples and may be attributed to anthropogenic sources. Based on the chloride and sulphate concentrations, Coffey classified the groundwater conditions as “moderate” exposure to concrete structures. Coffey states that there were some apparently anomalous sulphate concentrations where sulphate represents an unusually high proportion of the TDS, where normally chloride would be expected to be the major anion in groundwater. Locations with the highest TDS (MW7 and MW11) also had the highest proportions of sulphate in the TDS, suggesting there may have been a source of sulphate impact to groundwater on site. Coffey did not identify any patterns to the higher sulphate concentrations or any likely sources. Coffey suggested that it’s possible that sales, storage, and disposal of lead acid batteries at the site could have contributed to sulphate impacts; however, there is no evidence of impact of acid in the groundwater.

According to Coffey, all groundwater analytical results were reported below the adopted GWQOs with the following exceptions:

• MW6 and MW7 reported concentrations of benzene above the primary contact recreation GWQO of 1 μg/L;

• MW8, MW9 and MW10 reported concentration of MTBE above the agriculture, parks and gardens; stockwatering; and primary contact recreation GWQO of 20 μg/L;

• MW15 reported a concentration of arsenic exceeding the primary contact recreation GWQO of 7 μg/L;

• MW5, MW7, MW10, MW11 and MW14 reported concentrations of cadmium exceeding the maintenance of ecosystems GWQO of 0.2 μg/L;

• MW1, MW5 to MW15 reported concentrations of copper exceeding the maintenance of ecosystems GWQO of 1.1 μg/L;

• MW1, MW2, MW4 to MW7 and MW9 to MW15 reported concentrations of nickel exceeding the maintenance of ecosystems and primary contact recreation GWQOs of 11 and 20 μg/L respectively. The nickel concentration at MW11 also exceeded the agriculture, parks and gardens GWQO of 200 μg/L;

• All monitoring wells reported concentrations of zinc above the maintenance of ecosystems GWQO of 8 μg/L; and

• MW1, MW3, MW5 and MW12 reported pH values less than 5, the GWQO for buildings and structures.

According to Coffey, monitoring wells MW2, MW6, MW8, MW9, and MW10 contained concentrations of TPH C6-C9 above the laboratory LOR. Monitoring wells MW2, MW5, MW6, MW8 to MW10, MW13, and MW15 reported concentrations of TPH C10-C36 above the laboratory LOR. However, when the samples were analysed using silica gel clean-up, TPH C10-C36 concentrations were less than the laboratory LOR for all samples, indicating that the TPH C10-C36 is unlikely to originate from petroleum sources. Benzene was identified in two monitoring wells (MW6 and MW7) and toluene was identified in MW6 only. MTBE was identified in four monitoring wells (MW6, MW8, MW9 and MW10).



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A review of the potential beneficial uses to be protected by Coffey is summarised as follows:

• The identified petroleum hydrocarbons and metal concentrations are unlikely to adversely impact the nearest down gradient surface water body, Merri Creek due to the contaminant levels found in and adjacent to the site and the distance to the creek; and

• MTBE concentrations were detected above the adopted ILs for primary contact recreation and agriculture, parks and gardens. Coffey noted that MTBE is generally unpleasant in taste and odour and due to its small molecular size and solubility in water, moves rapidly in groundwater.

Coffey concluded that groundwater conditions onsite and offsite are not considered likely to preclude any of the relevant protected beneficial uses. Coffey noted that a qualitative Health Risk Assessment (HRA) and a Fate and Transport (F&T) study would be required to determine the potential health risks associated with possible residual hydrocarbon and MTBE impact in groundwater.

7.10 Groundwater Fate and Transport Modelling (Coffey, July 2009b) Coffey was commissioned by Mobil Oil Australia to conduct analytical Fate and Transport modelling of methyl tert-butyl ether (MTBE) identified in the groundwater at the former Mobil Service Station Northcote, located at 137-151 St Georges Road, Northcote, Victoria.

The objectives of the modelling were:

• To assess natural attenuation processes at the site; • To estimate the extent of impact likely to occur offsite as a result of the currently identified

contamination associated with an area of identified MTBE in the sub-surface at the site; • To predict the likely extent of dissolved phase plumes of MTBE; and • To determine the plume stabilisation times.

There are no Australian investigation levels for MTBE, therefore Coffey adopted the US EPA Human Health and Criteria Division (USEPA HECD) of the Office of Water Advisory contamination range of 20 to 40 μg/L. This guideline is based on aesthetic impacts rather than health effects.

The scope of the modelling was limited to mathematical screening level modelling.

BIOSCREEN-AT (Karanovic, 2007) was used to model the fate and transport of MTBE. Monitoring wells MW8 (edge of source), MW10 (middle of flow path) and MW13 (down-gradient well) were chosen for modelling purposes using the September 2008 data (Transect 1A) and May 2009 data (Transect 1B). Transect 1 was located directly south of the adopted source body. MW8 (edge of source) and MW17 (middle of flow path) were also chosen for modelling purposes using the May 2009 data (Transect 2). Transect 2 was located west-southwest of the adopted source body.

The key modelling results were:

• An assessment of primary and secondary indicators of natural attenuation was conducted. Evaluation of the data available indicated that natural attenuation through aerobic and anaerobic biodegradation is limited at the site;

• The modelling indicated that when the plume is in stablisised conditions, the adopted criteria for MTBE may be exceeded:

— Up to 25m down-gradient (south) of the adopted source zone in Transect 1A; — Up to 20m down-gradient (south) of the adopted source zone in Transect 1B; and — Up to 20m down-gradient (southwest) of the adopted source zone in Transect 2.



42 43512483/R001/A

• Residential properties are located approximately 52 m down-gradient and to the south of the source zone therefore MTBE concentrations in groundwater are unlikely to pose an unacceptable risk to users of the properties;

• Residential properties are located approximately 15 m down-gradient and to the west of the source zone therefore MTBE concentrations in groundwater would exceed the trigger value applied for the protection of the beneficial uses “primary contact recreation” and “agriculture, parks and gardens”. The adopted guideline value of 20 μg/L is considered conservative as it applies to aesthetic values of drinking water and is not specific to non-potable domestic use;

• The identified down-gradient potential groundwater receptor (Merri Creek located 550 m south/southwest of the site) is not likely to be impacted as a result of the identified impact.

7.11 2009 Post Phase 2 Environmental Site Assessment (Coffey, July 2009c)

Coffey was engaged by Mobil Oil Australia to undertake a Post Phase 2 Environmental Site Assessment (PP2 ESA) at the former Mobil Northcote Service Station located at the corner of St Georges and Arthurton Roads, Northcote.

The purpose of the PP2 ESA was to further delineate concentrations of MTBE identified within groundwater in the western portion of the site and reassess groundwater flow direction. Additionally, soil investigation works (three soil bores) were undertaken to further delineate previously identified soil impact along the boundaries of excavated areas (i.e. boundary validation samples TB-EW24 (2.4m bgs) at the eastern site boundary and TB-NW3 (0.5m bgs) at the northern site boundary).

The scope of works involved drilling of three soil bores (SB9, SB10, and SB11) in the footpath and two monitoring wells (MW16 and MW17) in the western portion of the site. Refer to Appendix D for the groundwater monitoring well borelogs. Gauging of all onsite and offsite groundwater wells and sampling and analysis of groundwater wells MW8, MW9, MW10, MW16 and MW17.

According to Coffey, the footpath investigation area was underlain by fill material between approximately 0.4 and 1.1m bgs followed by silty clay to approximately 2.5m bgs. The groundwater bores consisted of fill material (NDCR) to approximately 4.5m bgs, underlain by siltstone to 10m bgs (the limit of investigation).

One duplicate soil sample (QC6, duplicate of SB10-2.5) reported a concentration of benzo(a)pyrene of 1.1 mg/kg, which was above the NEPM HIL A criteria of 1 mg/kg. Several soil samples reported concentrations of arsenic, barium, manganese, nickel, and vanadium above the adopted ILs for maintenance of ecosystems.

The depth to groundwater ranged between 3.01m bgs (MW11) and 5.76 m bgs (MW15). The inferred flow direction was towards the south in the southern portion of the site and towards the west in the northern portion of the site.

There was no PSH or hydrocarbon odour noted in any of the 17 groundwater monitoring wells gauged.

Groundwater samples from MW8, MW9, MW10, MW16 and MW17 were analysed for TPH C10 – C36 (with and without silica gel clean-up), BTEX, MTBE, and TDS. BTEX results were reported below the LOR, whilst TPH C10 – C36 concentrations (without silica gel clean-up) were reported in some samples. TPH concentrations with silica gel clean-up were all reported to be below the LOR. MTBE concentrations in four of the five wells sampled were reported above the adopted criteria.



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Coffey concluded that MTBE concentrations were delineated in the northern, southern, and eastern portions of the site. According to Coffey, property boundary and access constraints limit the opportunity to delineate the full extent of the plume to the west. A comparison of MTBE concentrations between this round of sampling and that conducted in September 2008 indicates decreasing concentrations at wells MW8, MW9, and MW10. Fate and transport modelling would be necessary to provide an understanding of the likelihood of MTBE to impact offsite beneficial uses.

The closest surface water body is Merri Creek, located approximately 550m southwest of the site at its nearest point. The distance of the creek from the site makes it unlikely that groundwater contamination from the site is having any impact on the beneficial uses of surface water in the creek.

7.12 Groundwater Monitoring Event (Coffey, February 2010a) Coffey was engaged by Mobil Oil Australia to undertake a Groundwater Monitoring Event (GME) at the former Mobil service station located on the corner of St Georges Road and Arthurton Road, Northcote.

The purpose of the GME was to assess if any identified impact poses a threat to human health and/or the environment in relation to off-site conditions.

The specific objectives of the GME were:

• To assess the presence of PSH, dissolved phase hydrocarbons and MTBE in on and off-site wells; • Identify potential risks (if any) that the residual contaminants may pose to human health and the

environment; • Compare current groundwater conditions to previous conditions that existed at the site; and • Revise the existing fate and transport modelling to reflect current conditions at the site.

The scope of works involved gauging and sampling of all on and off-site groundwater monitoring wells and laboratory analysis of groundwater samples for TPH, BTEX, MTBE, sulphate, pH and TDS.

Depth to groundwater ranged between 2.55 (MW3) and 5.21 m bgs (MW17) and the inferred flow direction was towards the south in the southern portion of the site and towards the west in the northern portion of the site. PSH was not identified in any on or off-site wells.

Benzene was identified at MW7, with a maximum concentration of 3.9 µg/L. All other BTEX concentrations were reported below the LOR.

TPH C10-C36 concentrations were detected in MW3 (180 µg/L) and MW10 (130 µg/L). Silica gel clean up of these samples reported concentrations of TPH C10-C36 below the LOR of 100 ug/L, with the exception of MW3 which reported a concentration of TPH C15-C28 of 130 µg/L.

Concentrations of TPH C6-C9 were reported in samples MW2, MW5, MW9 and MW10. Generally the concentrations were consistent with the identified MTBE, with the exception of MW2 which recorded a concentration of TPH C6-C9 of 220 µg/L while MTBE was reported below the LOR of 5 ug/L. Coffey considered that this reported impact at MW2 was most likely due to a former on-site source of aliphatic hydrocarbons.

MTBE concentrations were reported above the adopted GWQO for beneficial uses agriculture, parks and gardens, and primary contact recreation at monitoring wells MW5, MW8, MW9, MW10 and MW17.



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According to Coffey, MTBE concentrations appear to be delineated to the north, south and east of the site, whilst concentrations have not been fully delineated to the west of the site. Further delineation is not possible due to the close proximity of the site boundary and the limited access in the adjacent laneway. The detection of MTBE at MW5 causes some uncertainty in the predicted offsite extent of the MTBE plume.

7.13 Health Risk Assessment (Coffey, July 2010b) Coffey was engaged by Mobil Oil Australia to undertake a Health Risk Assessment (HRA) at the former Mobil service station located on the corner of St Georges Road and Arthurton Road, Northcote.

The purpose of the HRA was to assess the potential health risks to on-site and off-site populations associated with impact currently identified in groundwater, based on the allowed residential land use on-site and existing residential use of properties located adjacent and hydraulically down-gradient of the site.

The results from the November 2009 and February 2010 groundwater sampling rounds were used for the assessment of petroleum hydrocarbon groundwater contamination at the site. The results from the September 2008 groundwater sampling round were adopted for metals.

Based on the identified beneficial uses, Coffey considered the most sensitive human health pathway to be primary contact recreation. To identify chemicals of potential concern for the vapour intrusion pathway, the USEPA (2009) Regional Screening Levels for Tap Water were adopted. These values are based on ingestion and inhalation of contaminants in domestic water supplies.

Residual soil impact was reported in the Further Tank Excavation Report along the northern boundary of the site at a minimum depth of 0.3 m bgs.

For the purpose of this assessment, the contaminants of potential concern (COPC) in groundwater were considered by Coffey to be:

• Benzene; • TPH C6-C9; • TPH C15-C28 (direct contact only); • MTBE; • Nickel (direct contact only); and • Sulphate (direct contact only).

For the purpose of this assessment, the COPC in soil were considered by Coffey to be:

• PAHs (direct contact only); and • TPH C15-C28 and TPH C29-C36 (direct contact only).

Based on the zoning of the site and surrounding properties, receptors of concern were considered to be:

• On-site residential occupants within a residential building; • On-site maintenance workers within a subsurface maintenance trench; • On-site construction workers within a subsurface excavation; • Off-site residential occupants within a residential building; and • Off-site maintenance workers within a subsurface maintenance trench.



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To assess the potential health risk to residential occupants, or maintenance and construction workers from the COPC, a vapour intrusion model provided in the Risk-Integrated Software for Clean-Ups (RISC 2003 V4.03) was utilised by Coffey. The model provides an estimation of vapour concentrations of COPC volatilised from groundwater or soil into a residential building, maintenance trench or excavation.

Based on the site conditions assessed, indoor air scenarios indicated that vapours emitted from groundwater are unlikely to pose an unacceptable incremental lifetime cancer risk to on-site and off-site residential occupants. Due to dilution effects and shorter exposure time it is also considered unlikely that groundwater impact at the site would pose an unacceptable incremental lifetime cancer risk to residents via outdoor air.

PAH impact detected in soil may pose a potential direct contact health risk to residential occupants, maintenance or construction workers in the vicinity of the residual soil impact along the northern site boundary. As this location is currently used as a footpath along Arthurton Road, Coffey considered it unlikely that the potential health risks will be realised.

Based on exceedances of the primary contact recreation guidelines the groundwater in the vicinity of the site is not considered suitable for extractive beneficial uses. Given the distance of current groundwater extraction bores and surface water bodies from the site, the calculated seepage velocity and the current contaminant concentrations, Coffey considered it unlikely that current registered extraction bores or surface water bodies would be impacted by the petroleum hydrocarbon plume.

7.14 Further Tank Excavation Assessment (Coffey, April 2010c) Coffey was engaged by Mobil Oil Australia (Mobil) to undertake a further Tank Excavation Assessment (TEA) at the former Mobil Northcote Service Station located at the corner of St Georges and Arthurton Roads, Northcote.

Three underground storage tanks (USTs) were identified in the north east corner of the site during previous investigations and were originally thought to be outside the title boundary. Following a review of the Certificate of Title and surveying of the site, it was determined the three USTs were within the site boundary, which extended under the footpath to the north and east. This TEA was undertaken to remove the three USTs and all known petroleum infrastructure and associated soil contamination within the title boundary to the extent practicable and to remove an area of soil on the northern boundary of the site which previously reported concentrations of BTEX and TPH above the adopted site assessment criteria to the extent practicable.

The objective of the proposed work was to verify that the soil remaining in the locations of the removed USTs would meet the site assessment criteria.

A total of 65 m3 of soil was excavated from two excavations during the removal of the three USTs (T9 – T11) and soil was stockpiled on site for subsequent analytical testing and characterisation. This soil was characterised in accordance with EPA guidelines and disposed off site to a licenced landfill.

The UST excavation was backfilled with ‘Liquidfill’, a cement based alternative to compacted fill. Approximately 10 m3 of validated quarry material was also delivered to the site and used to backfill the northern boundary excavation.

According to Coffey, excavated pits were successfully validated to meet “residential” clean-up criteria with respect to TPH, BTEX and phenols.



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Concentrations of benzo(a)pyrene and total PAH, however, exceeded health investigation levels (HILs) in validation samples collected from the walls of the excavation that were underneath the footpath adjacent to St Georges and Arthurton Roads.

According to Coffey, a meeting between a representative of VicRoads and JFTA (the principal excavation contractor) was conducted on site prior to the removal of the USTs. From these discussions, and given the location of the soils containing residual contamination at concentrations exceeding adopted criteria, it was considered impractical to excavate the impacted soil for the following reasons:

• The presence of underground services such as optical fibre under the footpath along St Georges and Arthurton Roads;

• The potential subsidence of the adjacent road surfaces given that the excavation was within 1 m from the road surface and 2 m below the ground level; and

• High traffic volume on St Georges and Arthurton Roads adding to the potential for subsidence of the excavation.

Concentrations of vanadium, barium and zinc exceeded EILs in some of the soil validation samples. These metal concentrations were considered to be indicative of natural/background concentrations.

According to Coffey, some residual hydrocarbon staining and odour may be detected during future excavation works on site (in the footpath area), however, Coffey consider that it is unlikely that the odour levels would represent an aesthetic concern in the context of the proposed future “residential” use of the site.

According to Coffey, all known petroleum infrastructure and associated impacted soil has been removed from the site to the extent practicable.

7.15 Interim Groundwater Monitoring Event (Coffey, August 2010d) Coffey was engaged by Mobil Oil Australia (Mobil) to undertake an interim Groundwater Monitoring Event (GME) at the former Mobil Northcote Service Station located at the corner of St Georges and Arthurton Roads, Northcote.

The purpose of the GME was to assess the groundwater conditions at the site and use the analytical data to refine the Fate and Transport model of contaminant behaviours (specifically MTBE).

The specific objective of the interim GME was to assess whether MTBE concentrations beneath the site continue to change or are stabilising and to re-assess the concentration of sulphate beneath the site using a more appropriate laboratory method.

Ten on-site and two off-site monitoring wells were sampled in February 2010. Four monitoring wells (MW5, MW8, MW10 and MW17) were re-sampled in July 2010 at the request of the Auditor (see Section 8.3).

The depth to groundwater in February 2010 across the site ranged from 2.8 (MW11) to 4.9 m bgs (MW13). Coffey did not encounter any PSH in the monitoring wells during the February or July 2010 monitoring rounds.

Based on the groundwater contour plan for the February 2010 data, the inferred groundwater flow direction is generally south (towards Merri Creek), however, groundwater flow in the northern portion of the site has a more westerly flow (also towards Merri Creek).



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TDS concentrations ranged from 680 mg/L (MW16) to 6,120 mg/L (MW17) in February 2010, and Coffey classified the groundwater beneath the site as within Segment B of the Groundwater SEPP.

TDS concentrations reported during the July 2010 monitoring event ranged from 1,100 mg/L (MW5) to 4,700 mg/L (MW17). With the exception of the TDS concentration at MW17, all TDS values fell within Segment B and were considered consistent with the February 2010 TDS concentrations.

Sulphate concentrations at two locations (MW7 and MW11) exceeded the reported TDS concentrations. This was also observed in the November 2009 GME. The laboratory was requested to use a different analytical method (ion chromatography), however, results were similar to those from the previous analysis.

Concentrations of TPH C6-C9 above the laboratory LOR were reported at MW5, MW8, MW9 and MW10. The distribution of TPH C6-C9 was consistent with that for MTBE.

Detectable concentrations of TPH C10-C36 were identified in MW5 and MW11. After silica get clean up, TPH C10-C36 concentrations were reported to be below the laboratory LOR.

Concentrations of BTEX and lead were less than the laboratory LORs.

Concentrations of MTBE were above the adopted IL of 20 ug/L (USEPA, December 1997) at MW5, MW8, MW9, MW10 and MW17, with concentrations ranging from 29 to 281 ug/L in February 2010.

MTBE concentrations were lower in the July 2010 sampling round in the four re-sampled wells. Concentrations remained above the adopted IL in MW5, MW8 and MW10.

Coffey re-calibrated the fate and transport model using the February 2010 MTBE concentration data. Along the south-westerly transect (MW8 to MW17), the modelling indicated that when the impact was in stabilised conditions (ie after 15 years), the adopted MTBE IL of 20 ug/L may be exceeded up to 10 m down-gradient of the adopted source zone (MW8) and within the site boundary.

MW10 is located in the middle of the flowpath if it is assumed the source zone is MW10. MW13, which has reported MTBE concentrations below the LOR since September 2008, is located down-gradient of MW10, therefore it is considered by Coffey that MTBE concentrations in MW10 are unlikely to migrate off-site.

The modelling indicated that when the impact was in stabilised conditions, the adopted MTBE IL of 20 ug/L may be exceeded up to 24 m down-gradient of the adopted source zone (MW5) along the westerly transect. Coffey noted that although MW5 is located 15 m from the site boundary, the modelling also indicated that the upper limit of the USEPA HECD aesthetic value of 40 ug/L would be unlikely to be exceeded at distances more than 18 m down-gradient of MW5. Coffey concluded that while the predicted MTBE concentrations beneath the adjoining residential properties may exceed the adopted IL, they would be within the range recommended by the USEPA, but unlikely to exceed it.


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8

8 Quality of Site Assessment Data

8.1 General In order to characterise the environmental condition of a site, an Auditor must be satisfied with the extent and quality of the site assessment data provided. The following is a critical appraisal of the site assessor’s investigation. It addresses the following:

• Appropriateness and completeness of the assessment with respect to the potential for contamination on the site;

• Validity of the investigation data with respect to data quality; and • Appropriate and correct interpretation of the data and justification for the assessment conclusions.

The quality of the site assessment validation data pertaining to the site conducted by Handex (1998), ITE (2004) and Coffey (2006 to 2010) is assessed in the following sections.

The objective of the data collection activities was to provide a representative assessment of the site's environmental condition to evaluate whether the site's beneficial use/s had been impacted by activities either on or off-site. This was achieved through the investigation of the presence or absence of likely contaminants, based on a background review identifying potential contamination sources, through the completion of an appropriate sampling and analysis program.

The Auditor considers that the scope of the assessments was broadly consistent with achieving these objectives.

8.2 Sampling Spatial Density

8.2.1 Soil The site has an area of approximately 0.20 hectares. The initial site contamination assessment (Handex, 1998) comprised of 19 primary sample locations.

This sampling density exceeds the minimum number of sample locations for a site area of approximately 0.20 hectares recommended in the Australian Standard AS4482.1-2005 (7 sample locations for a site area of 0.2 hectares). The recommended sampling density is based on detection of circular hot spots using square grid and does not take into account sample locations that target specific areas.

Remediation works undertaken between 2003 and 2010 resulted in the excavation of the top 3 to 4 m of soil across the whole site, thereby removing the original 19 soil sample locations. Therefore, the laboratory results pertaining to these locations are no longer relevant to the outcome of the Audit.

Approximately 320 primary soil samples were collected and analysed across the site for validation purposes during four separate phases of remediation works. Samples were collected at a minimum rate of one sample from the base and each wall of all excavations in accordance with the NSW EPA Service Station Guidelines (1994).

At the completion of remedial works in 2010, Coffey analysed a total of 25 soil samples from twelve soil bore locations that were converted into groundwater monitoring wells across the site within the excavated areas (soil samples were not collected during drilling of MW17 as the drilling technique required, air hammer, resulted in the potential loss of volatiles, thus compromising the integrity of the samples). Sampling density for soil samples across the site was approximately 1 in 154 m2. Another eight soil bores were also drilled across the site in a systematic grid formation to assess the soils for the beneficial use “buildings and structures”.



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The Auditor is satisfied that the soil sampling density undertaken at the site is sufficient to characterise the environmental condition of the site prior to and following remedial works undertaken.

8.2.2 Groundwater Seventeen groundwater monitoring wells have been installed by Coffey at and around the site (thirteen on-site and four off-site). The locations of these wells are illustrated on Figure 2 and reflect the:

• Site history (ie. location of potential sources of groundwater contamination); • Distribution of the contamination across the site; and • Up-gradient and down-gradient groundwater conditions on and off-site.

The Auditor notes that the standing water level was above the well screen in MW1 and MW5 – MW17 during the entire monitoring period (2008 to 2010). MW1, located off-site, was the first well to be installed and due to the confined to semi-confined nature of the aquifer beneath the site, the water level rose more than expected and above the well screen. Monitoring wells MW5 to MW15 were installed post-remediation through the crushed rock backfill material which extended approximately 3 to 4 m bgs across the site. Therefore, to prevent the potential for cross-contamination into the clean backfill material, the well screens were installed below the backfill material within the natural siltstone.

These wells are therefore potentially incapable of intercepting and monitoring phase separated hydrocarbons (PSH) if it were to be present around these wells, however, given the low concentrations of total petroleum hydrocarbons (TPH) identified in the soil and groundwater at these locations and the absence of any visible PSH during remedial activities, it is unlikely PSH is present beneath the site. It is also noted that saturated soil was not intersected during excavation works and that groundwater inflow into the excavations was not noted.

The Auditor considers the monitoring well network is adequate to address potential contaminant sources and the current and potential impact of contamination on beneficial uses of groundwater at the site.

8.3 Field Protocols Handex (1998) reported that soil and groundwater sampling was carried out in accordance with Australian and New Zealand Guidelines for the Assessment and Management of Contaminated Sites, 1992, and the Australian Standard, Guide to the sampling and investigation of potentially contaminated soil, Part 1: Non-volatile and semi-volatile compounds, AS 4482.1-1997. Field methodology adopted is included as Appendix C of the Handex 1998 report (attached as Appendix F).

ITE (2006) reported that the tank excavation assessment was completed in accordance with the ‘Environmental Site Assessment Specification’ – GRA-S-ESA-REV1, issued 5 March 2002. Section 4.3 of ITE’s report outlines the field methods employed for the assessment (attached as Appendix F).

Coffey reported that all phases of work were completed in accordance with the Mobil Specification (March 2002).

With respect to the sampling methodologies employed, the Auditor makes the following comments in regards to specific phases of work.



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Environmental Site Assessment (Handex, 1998) The Auditor notes the following with respect to Handex’s sampling methodology documented in Handex (1998):

• There were no details provided regarding whether the groundwater well was developed prior to sampling and what methodology was employed;

• Details regarding the soil sampling methodology using the geoprobe soil probing rig were outlined in Appendix C of the Handex report, however, no details regarding the methodologies employed to collect the perched water and groundwater samples were provided; and

• Calibration certificates for field meters were not included in the final report.

Tank Excavation Assessment (ITE, 2004) The Auditor notes the following with respect to ITE’s sampling methodology documented in ITE (2006):


Further Tank Excavation Assessment (Coffey, 2007) The Auditor notes the following with respect to Coffey’s sampling methodology documented in Coffey (2007):


Post Phase 2 Environmental Site Assessment (Coffey, 2008c) The Auditor notes the following with respect to Coffey’s field protocol’s documented in Coffey (2008c):

• Monitoring wells MW1, MW5 to MW15 were all screened below the water level. 100 mm conductor casing was installed at each on-site well location (MW5 to MW15) between 0.5 and 1.0 m below the NDCR backfill material (typically 3 to 4 m below ground surface across the site) to prevent surface water infiltration into the monitoring wells. It was therefore agreed between Coffey and the Auditor that the screened casing would start at the base of the conductor casing.

Groundwater Monitoring Event (Coffey, 2010a) The Auditor notes the following with respect to Coffey’s field protocol’s documented in Coffey (2010a):

• Significant drawdown occurred during groundwater sampling in November 2009 at monitoring wells MW4, MW5, MW14, MW15 and MW16. This was especially evident in wells MW5, MW15 and MW16, where drawdown equivalent to approximately 1.5 – 2 L of groundwater was observed and approximately 3 L of water was purged form the well during sampling. The Auditor requested that during future GMEs, either drawdown should be kept to a minimum (ie. < 100 mm), drawdown stabilises after the initial drawdown, or the volume of water purged far exceeds the volume of drawdown to ensure that water sampled is being sourced from the aquifer and not from the well.

Further Tank Excavation Assessment Report (Coffey, 2010c) The Auditor notes the following with respect to Coffey’s field protocol’s documented in Coffey (2010c):




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Interim Groundwater Monitoring Event (Coffey, 2010d) The Auditor notes the following with respect to Coffey’s field protocol’s documented in Coffey (2010d):

• Excessive drawdown was observed during groundwater sampling in February 2010 at monitoring wells MW8, MW9, MW10, MW11, MW12, MW16 and MW17. At the Auditor’s request, monitoring wells MW5, MW8, MW10 and MW17 were re-sampled in July 2010 to ensure groundwater samples were representative of the aquifer. Coffey noted that during re-sampling, the monitoring wells experienced an initial drawdown of approximately 2 m, then appeared to stabilise. Samples were collected following stabilisation of field parameters. The Auditor has relied upon the July 2010 results (and not the February 2010 results) for MW5, MW8, MW10 and MW17 for interpretive use.

The Auditor is satisfied that field protocols adopted by the site assessors were appropriate to ensure representative samples for characterisation of site conditions.

8.4 Laboratory Method Protocols The Auditor reviewed the analytical methods and analytical limits of reporting (LORs) used by the five laboratories, AGAL, Amdel, MGT, ALS and LabMark. The laboratories used different methodologies (with different LORs), for performing several soil and groundwater analyses. Analytical methods and LORs for soil and water are included in Table 8-1 and Table 8-2 below. The Auditor was not able to determine whether laboratory methods (or parts thereof) were compliant with standard methods published by NEPM, AWWA and USEPA.

Analytical methodologies accredited by the National Association of Testing Authorities (NATA) indicate that the methods adopted by each laboratory have been assessed and approved by an independent body for their competence in reporting accurate and reliable results. The Auditor has not verified the laboratory methods through a detailed audit. However, all laboratories used this investigation reported on the Certificate of Analysis that the document issued was in accordance with NATA accreditation requirements.



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Table 8-1 Soil Analytical Methods and Corresponding Laboratory LORs

Analysis AGAL (1998 / 2003)

LOR (mg/kg)

Amdel (1998 /

2003 -2005 / 2007 / 2008)

LOR (mg/kg)

MGT (2005 / 2007)

LOR (mg/kg)

ALS (2007 - 2010)

LOR (mg/kg)

LabMark (2008-2010)

LOR (mg/kg)

pH - - - - - - EA002 0.1- - - Cyanide NWS5B 0.5 236 / E3450 /

4270 0.1-0.5 USEPA

9010B 5 EK026 1 - -

Heavy Metals AGAL VL239 / 250

0.5 – 50 E5910/406-MS / 3100

0.5-5 USEPA 6010B

0.1-10 EG005T 1-50 3100 2

Mercury - - E5950 / 404FIMS / 3400

0.01-0.05 USEPA 7470/71

0.1 EG035T 0.1 3400 0.01

Total Cr 6+ - - 235 NK - - EG050S 1 - - Chloride - - - - - - ED045 10 - - Fluoride VL248 0.1 208 / E3500 2 / 10 USEPA

SW846 20 EK040T 40 - -

Sulfate (SO4) - - - - - - ED040N 50 - - TPH (C6-C9) AGAL VL234 25 E1230 /

513P&T / 1100

5 MGT100A-GC

20 EP080 10 1100 5

TPH (C10-C36) AGAL VL228/229

50 – 100 E1221 / 501-FID / 2000

10-50 MGT100A-GC

50-100 EP071 50-100 2000 10-20

BTEX/MAH AGAL VL234 0.5-1 E1010 / 504P&T / 513P&T / 1100

0.2-2 USEPA 8260B

0.05 EP080 0.2-0.5 1100 0.2-2



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Analysis AGAL (1998 / 2003)

LOR (mg/kg)

Amdel (1998 /

2003 -2005 / 2007 / 2008)

LOR (mg/kg)

MGT (2005 / 2007)

LOR (mg/kg)

ALS (2007 - 2010)

LOR (mg/kg)

LabMark (2008-2010)

LOR (mg/kg)

PAHs NGCMS11_22 0.1 E1110 / 512-MS / 2100

0.5-1 USEPA 8270C

0.1 EP075(SIM)B 0.5 2100 0.5-1

Phenols APHA5530D NK 244 / E1142 / 4850

0.1 USEPA 8270C

0.1-0.5 EP075(SIM)A 0.5-2 4850 0.1

Cresols - - - - HPLC 464 0.1 - - - - OC and OP pesticides

VL206 0.1 E1081 / 512-MS / 2300

0.1-0.5 USEPA 8081A / 8141A

0.05-0.1 EP068A 0.05 - -

PCBs VL206 0.2 E1081 / 512-MS / 2600

0.1-1 USEPA 8082

0.1 EP066 0.1 - -

VHCs - - E1270 / 504P&T / 1300

0.1-1 USEPA 8021B, 8260B, MGT400A

0.1 - - 1300 1-5

Halogenated Volatile Hydrocarbons

VL234 1 - - USEPA 8260B

0.05-0.2 EP074D, EP074E, EP074F, EP074G

0.5-5 - -

NK LOR not

provided

- Not Analysed



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Table 8-2 Water Analytical Methods and Corresponding Laboratory LORs

Analysis AGAL (1998)

LOR (mg/L)

Amdel (1998 / 2003 / 2004, 2007 / 2008)

LOR (mg/L) ALS (2007-2010) LOR (mg/L) LabMark

(2008-2010) LOR (mg/L)

pH - - 4000 0.1 EA005P 0.01 4000 0.1 TDS - - 4110 5 EA015 1 4110 20 TOC - - 4410 1 EP005 1 4410 1 Chloride - - 4300 0.5 ED045P 1 4300 0.5 Sulphate (SO4) - - 4300 0.5 ED040F / ED041 /

ED009 1 4300 0.5

Cyanide - - E2450 / 236 0.005 EK026 0.005 - - Fluoride - - E2500 / 208 0.1-0.5 EK040P 0.1 - - Heavy Metals AGAL

VL239/250 0.5 – 5.0 E4870 / E4910 / 406-

MS / 3100 / 404-MS 0.0002-0.2 EG020F 0.0001-0.01 3100 0.001-0.005

Mercury - - E4950 / 404FIMS / 3400

0.0001-0.001 EG035F 0.0001 3400 0.0001

Iron - - - - EG005F 0.01 3200 0.1 Ferrous Iron - - 4240 0.05 EG051G 0.05 4240 0.05 Ferric Iron - - Ferric iron 0.05 EG053FG 0.05 Ferric iron 0.05 Nitrite - - - - EK057G 0.01 - - Nitrate - - - - EK058G 0.01 4300 0.5 TPH (C6-C9) AGAL VL234 25 E0230 / 513P&T /

1200 0.02 EP080 0.02 1100 0.02

TPH (C10-C36) AGAL VL228/229

50 – 100 E0221 / 501-FID / 2000

0.02-0.2 EP071 0.05-0.1 2000 0.04-0.1

BTEX/MAH AGAL VL234 25 E0010 / 504P&T / 513P&T / 1200

0.0005-0.003 EP080 0.001-0.002 1100 0.0005-0.002



43512483/R001/A 55

Analysis AGAL (1998)

LOR (mg/L)

Amdel (1998 / 2003 / 2004, 2007 / 2008)

LOR (mg/L) ALS (2007-2010) LOR (mg/L) LabMark

(2008-2010) LOR (mg/L)

PAHs and Total PAH’s

- - E0110 512-MS / 2100

0.001-0.002 EP075(SIM)B 0.0005-0.001 2100 0.001-0.002

Phenols - - E0142 / 244 / 4850 0.00001-0.04 EP075(SIM)A 0.001-0.002 4850 / 2800 0.01-0.04 OC and OP pesticides - - E0081 / 512-MS 0.001 EP068A / EP075I,

EP075J 0.002-2 2200 and 2400 0.001-0.002

PCBs - - E0081 / 512-MS 0.001-0.01 EP066 0.001 2600 0.001-0.002 Methane - - Dissolved methane NK EP033 0.01 Dissolved

methane NK

MTBE - - - - EP074L 0.005 - - VHCs - - E0270 / 1300 0.001-0.03 - - 1300 0.005-0.03 SVOC scan - - - - EP075C, EP075D,

EP075E, EP075F, EP075G, EP075H

0.002-0.02 - -

Halogenated volatile organics

- - - - EP074D, EP074E, EP074F EP074G, EP074H, EP074J, EP074K

0.005-0.05 - -

NK LOR not

provided

- Not Analysed



56 43512483/R001/A

8.5 Analytical Data Validation Procedure Analytical data validation is the process of assessing whether data are in compliance with method requirements and project specifications. The primary objectives of this process are to ensure that data of known quality are reported, and to identify if the data can be used to fulfil the overall project objectives.

The data validation guidelines adopted are based upon AS4482.1-2005 and data validation guidance documents published by the United States Environmental Protection Agency (US EPA). The process involves an assessment of the accuracy and precision of analytical data from a range of quality control measurements, generated from both the sampling and analytical programs.

Specific elements of data validation that can be readily checked and assessed for ESA projects include:

• preservation and storage of samples upon collection and during transport to the laboratory; • sample holding times; • use of appropriate analytical and sampling procedures; • required limits of reporting; • frequency of conducting quality control measurements; • laboratory blank results; • field blank results; • trip blank results; • field duplicate results; • laboratory duplicate results; • matrix spike/matrix spike duplicate (MS/MSD) results; • surrogates spike results; and • the occurrence of apparently unusual or anomalous results, e.g. laboratory results that appear to

be inconsistent with field observations or measurements.

The following discussion summarises the findings of the data quality review undertaken on each of the intrusive phases of works at the site.



43512483/R001/A 57

8.5.1 Analytical Data Validation

Environmental Site Assessment (Handex, 1998)

Table 8-3 Analytical Data Validation – ESA (Handex, 1998)

Data Validation Item

Auditor Comments

Anomalous Results A review of the analytical results relative to observations made during the fieldwork program did not identify any anomalous results.

Quality Control Measures

Frequency of Field Quality Control Measurements

Field quality control procedures were not compliant with those defined in AS4482.1-1997 with respect to collection and/or analysis of equipment rinsate, field blank and trip blanks. There were no rinsate or blank samples collected or analysed. The Auditor therefore considers that this does not allow for a thorough assessment of the potential for false positive results from contamination of sampling equipment or cross contamination between samples. However, given that the entire site was subsequently excavated to approximately 3 mbgs, and the groundwater well was abandoned, the majority of soil samples collected by Handex are no longer relevant.

Sample Preservation and Handling

During sampling, field samples were handled and preserved in accordance with AS4482.1-1997. The temperature of samples upon arrival at the laboratory was not reported by the primary laboratory, however, it was noted on the COC that samples were stored with ice.

Sample Holding Times

The compliance with maximum holding times prior to analysis was not reported by the laboratory (AGAL) for soil samples collected. Therefore the Auditor is not able to verify that samples were analysed within recommended holding times.

Blank Monitoring Results for laboratory method blanks were below the limits of reporting for the analytes tested, however, the AGAL report for the grid point soil analysis did not report blank results for all analysis performed. Rinsate blanks, field blanks and trip blanks were not collected for the soil or groundwater sampling program. As discussed above, the analytical results are no longer considered relevant given the entire site was subsequently excavated.

Data Precision

Laboratory Duplicates (Primary Laboratory)

Laboratory duplicates were not reported for all analytes by AGAL for soils and Amdel for soils and water. The Auditor is therefore unable to verify that the laboratory method precision (repeatability) is acceptable.

Field Duplicates (Primary Laboratory)

Field duplicates were collected and analysed for soil samples, however, there were no field duplicates collected for groundwater. Data generated for the analyses of soil field duplicates indicate an acceptable degree of precision (repeatability) in the laboratory methodology and minimal variation of target compounds within the sample matrices. The auditor considers that the precision (repeatability) of the data reported is acceptable.

Field Triplicates (Secondary QC Laboratory)

There were no field triplicate samples collected or analysed for soil or groundwater. Therefore, the auditor was not able to verify the precision (reproducibility) of the data reported.

Internal Laboratory Protocols

Frequency of Laboratory Quality Control Measurements

Laboratory duplicates were undertaken at a rate of 10% by AGAL for the soil grid point analysis, and all results were within the acceptable limits. AGAL did not report sufficient matrix spike recoveries. Amdel reported sufficient matrix spike recoveries and laboratory duplicates for soil and groundwater.



58 43512483/R001/A


Auditor Comments

Limits of Reporting (LOR)

The majority of standard laboratory LORs for soil analyses were below the adopted criteria outlined in Section 6 (provided in Table 1) and are considered acceptable, with the exception of benzene, for which the LOR is greater than the adopted guideline. This exception is discussed in Section 8.5.2. The majority of standard laboratory LORs for groundwater analysis were below the adopted groundwater criteria outlined in Section 6 (provided in Table 2) and are considered acceptable, with the exception of lead and benzene, where the LORs were greater than the adopted guidelines. These exceptions are further discussed in Section 8.5.2, below.

Surrogate and Matrix Spike Recoveries

Surrogate and matrix spike recoveries were generally within the acceptable laboratory control limits for the samples analysed. The data indicates there was no significant bias in the quantitation of analytes present in individual samples.

Tank Excavation Assessment (ITE, 2004)

Table 8-4 Analytical Data Validation - TEA (ITE, 2004)


Auditor Comments




Field quality control procedures were undertaken in accordance with AS4482.1-1997 with respect to collection and/or analysis of equipment rinsate, field blank and trip blank samples.


During sampling, field samples were handled and preserved in accordance with AS4482.1-1997 and EPA 441.7-2000. However, it is noted that the temperature of samples upon arrival at the laboratory was not recorded for all sample batches.


The compliance with maximum holding times prior to analysis was not reported for all sample batches, therefore the Auditor is not able to verify that samples were analysed within recommended holding times for all samples collected. Laboratory batches which reported holding time data indicate samples were extracted and analysed within acceptable time frames.

Blank Monitoring All laboratory method blank, equipment blank, field blank and trip blank results were reported below the laboratory limits of reporting for the analytes tested, with the exception of equipment and field blank samples collected on the 16/06/03 and 17/06/03 for bromodichloromethane and chloroform. ITE states in its report that neither of these analytes were detected in the soil samples and given the similarity of the results, it is likely that the laboratory supplied water was contaminated with these analytes. The Auditor does not consider the quality of the soil samples have been adversely affected. The Auditor also notes that the full suite of parameters were not analysed for the equipment and field blanks collected on the 11/06/03, however, the auditor is satisfied that the analysis undertaken for the primary analytes of concern (TPH, BTEX and lead) is sufficient.

Data Precision


Laboratory duplicates were not reported for all analytes by Amdel. The Auditor is therefore unable to verify if the laboratory method precision (repeatability) is acceptable for one of the batches. However, laboratory duplicates analysed for all other batches indicate the laboratory method precision is acceptable.



43512483/R001/A 59


Auditor Comments


Field duplicates were collected and analysed at an acceptable rate of one per 20 samples. Data generated for the analyses of soil field duplicates indicate an acceptable degree of precision (repeatability) in the laboratory methodology and minimal variation of target compounds within the sample matrices. The auditor considers that the precision (repeatability) of the data reported is acceptable.


Field triplicates were collected and analysed at an acceptable rate of one per 20 samples. Data generated for the analyses of soil field triplicates indicate an acceptable degree of precision (repeatability) between the laboratory methodologies and minimal variation of target compounds within the sample matrices. The auditor considers that the precision (repeatability) of the data reported is acceptable.



Laboratory duplicates were generally undertaken at a rate of 10% and all results were within the acceptable limits. Sufficient matrix spike recoveries were also reported. One Amdel laboratory report, however, did not report any laboratory QC data, therefore the Auditor is unable to verify the frequency of laboratory control measurements for that batch.


The majority of standard laboratory LORs for soil analyses were below the adopted criteria outlined in Section 6 (provided in Table 1) and are considered acceptable, with the exception of benzene, TCE and PCE for which the LORs are greater than the adopted guidelines. These exceptions are discussed in Section 8.5.2.



Further Tank Excavation Assessment (Coffey, 2007)

Table 8-5 Analytical Data Validation - Further TEA (Coffey, 2007)


Auditor Comments




Field quality control procedures were undertaken in accordance with AS4482.1-2005 for most days of validation sampling with respect to collection and/or analysis of equipment rinsate, field blank and trip blank samples. QAQC samples were not collected and analysed for four of the thirteen days of sampling.





60 43512483/R001/A


Auditor Comments


The compliance with maximum holding times prior to analysis was not reported for all sample batches, therefore the Auditor is not able to verify that samples were analysed within recommended holding times for all samples collected. However, the laboratory reports were generally issued within a week of receiving the soil samples, therefore the samples are likely to have been analysed within holding times. Laboratory batches which reported holding time data indicate samples were extracted and analysed within acceptable time frames.

Blank Monitoring All laboratory method blank, equipment blank, field blank and trip blank results were reported below the laboratory limits of reporting for the analytes tested, with the exception of equipment blank, QC5, which reported a concentration of zinc of 6 μg/L, and field blank QC4 which reported concentrations of barium (1 μg/L) and zinc (12 μg/L). Coffey does not provide an explanation for these positive blank results, however, given the low concentrations reported and the fact that both these blank samples were collected on the same day, it is possible the rinsate water supplied by the laboratory was slightly contaminated and the Auditor does not consider the quality of the soil samples have been adversely affected.

Data Precision


Laboratory duplicates were undertaken for all sample batches and indicate the laboratory method precision is acceptable.


Field duplicates were collected and analysed above the acceptable rate of one per 20 samples. Data generated for the analyses of soil field duplicates indicate an acceptable degree of precision (repeatability) in the laboratory methodology and minimal variation of target compounds within the sample matrices. The auditor considers that the precision (repeatability) of the data reported is acceptable.


Field triplicates were collected and analysed above the acceptable rate of one per 20 samples. Data generated for the analyses of soil field triplicates indicate an acceptable degree of precision (repeatability) between the laboratory methodologies and minimal variation of target compounds within the sample matrices. The auditor considers that the precision (repeatability) of the data reported is acceptable.



Laboratory duplicates were generally undertaken at a rate of 10% and all results were within the acceptable limits. Sufficient matrix spike and surrogate recoveries were also reported.


The majority of standard laboratory LORs for soil analyses were below the adopted criteria outlined in Section 6 (provided in Table 1) and are considered acceptable, with the exception of benzene, TCE and PCE for which the LORs are greater than the adopted guidelines. These exceptions are discussed in Section 8.5.2.





43512483/R001/A 61

Phase 2 Environmental Site Assessment (Coffey, 2008a)

Table 8-6 Analytical Data Validation - Phase 2 ESA (Coffey, 2008a)


Auditor Comments




Field quality control procedures were generally undertaken in accordance with AS4482.1-2005 for soil and groundwater sampling with respect to collection and/or analysis of equipment rinsate, field blank and trip blank samples. Two sets of QAQC samples (rinsate, field and trip blank samples) were collected on one day of soil sampling and not collected on another.


During sampling, field samples were handled and preserved in accordance with AS4482.1-2005 and EPA 441.7-2000. The temperature of samples upon arrival at the laboratory was recorded for all sample batches and noted to be above 4oC, however, ice or icebricks were noted to be present when received by the laboratory.


The interpretive quality control reports for the ALS sample batches were not provided by Coffey, therefore the Auditor was not able to verify that samples were analysed within recommended holding times for all samples collected. However, the laboratory reports were generally issued within one to two weeks of receiving the samples, therefore the samples are likely to have been analysed within holding times. Amdel laboratory batches reported holding time data which indicated samples were extracted and analysed within acceptable time frames.

Blank Monitoring All laboratory method blank, equipment blank, field blank and trip blank results were reported below the laboratory limits of reporting for the analytes tested, with the exception of positive results in a number rinsate blanks and field blanks for both the soil and groundwater sampling programs. Low concentrations of metals (cobalt, copper and iron), inorganics (nitrate, nitrogen, TOC) and/or chloroform were detected in the QC samples. Coffey noted that the laboratory (ALS) confirmed that the deionised water supplied by the laboratory contained impurities which may be detected in the analysis. According to Coffey, chloroform, cobalt and iron are not contaminants of concern at the site, and copper is considered naturally occurring, therefore the field QC results are acceptable for the purposes of this investigation. The Auditor does not consider the quality of the soil samples have been adversely affected.

Data Precision


Laboratory duplicates were undertaken for all sample batches and indicate the laboratory method precision is acceptable.


Field duplicates were collected and analysed at the acceptable rate of one per 20 samples. Data generated for the analyses of soil field duplicates indicate an acceptable degree of precision (repeatability) in the laboratory methodology and minimal variation of target compounds within the sample matrices. The auditor considers that the precision (repeatability) of the data reported is acceptable.


Field triplicates were collected and analysed above the acceptable rate of one per 20 samples. Data generated for the analyses of soil field triplicates indicate an acceptable degree of precision (repeatability) between the laboratory methodologies and minimal variation of target compounds within the sample matrices. The auditor considers that the precision (repeatability) of the data reported is acceptable.



62 43512483/R001/A


Auditor Comments



Laboratory duplicates were generally undertaken at a rate of 10% and all results were within the acceptable limits. Sufficient matrix spike and surrogate recoveries were also reported.


The majority of standard laboratory LORs for soil and groundwater analyses were below the adopted criteria outlined in Section 6 (provided in Tables 1 and 2) and are considered acceptable, with the following exceptions for soil and groundwater. The LORs for benzene, TCE, PCE and cis-1,2-DCE for soil samples are greater than the adopted guidelines. The LORs for a range of metals, PAHs and chlorinated hydrocarbons, and nitrate and nitrite for groundwater samples are greater than the adopted guidelines (primarily in regards to the secondary laboratory, LabMark). These exceptions are discussed in Section 8.5.2.



Soil Validation Assessment (Coffey, 2008b),

Table 8-7 Analytical Data Validation - Soil Validation Assessment (Coffey, 2008b)


Auditor Comments




Field quality control procedures were generally undertaken in accordance with AS4482.1-2005 with respect to collection and/or analysis of equipment rinsate, field blank and trip blank samples. The Auditor notes that no field quality samples were collected or analysed during the soil bore drilling and sampling on 22 September 2008.


During sampling, field samples were generally handled and preserved in accordance with AS4482.1-2005 and EPA 441.7-2000. However, it is noted that the temperature of samples upon arrival at the laboratory was not recorded for all sample batches.


The compliance with maximum holding times prior to analysis was not reported for all sample batches, therefore the Auditor is not able to verify that samples were analysed within recommended holding times for all samples collected. However, the laboratory reports were generally issued within a week of receiving the soil samples, therefore the samples are likely to have been analysed within holding times. Laboratory batches which reported holding time data indicate samples were extracted and analysed within acceptable time frames.



43512483/R001/A 63


Auditor Comments

Blank Monitoring All laboratory method blank, equipment blank, field blank and trip blank results were reported below the laboratory limits of reporting for the analytes tested, with the exception of positive results in a number rinsate blanks and field blanks for both the soil and groundwater sampling programs. Low concentrations of metals (arsenic, barium, cadmium, copper, manganese, mercury and zinc), TPH C10-C36 fractions and/or chloroform were detected in the QC samples. Coffey provided the following explanations for the positive results: • Chloroform was not detected in any of the primary samples; • The metals concentrations were generally low and not high enough to have an

impact on the reported soil concentrations and indicative of contaminated deionised water;

• Concentrations of TPH in soil samples collected on the same day as the contaminated blank samples were reported less than the laboratory LOR.

The Auditor accepts these explanations and does not consider the quality of the soil samples has been adversely affected.

Data Precision


Laboratory duplicates were not undertaken for all secondary laboratory sample batches therefore the Auditor is unable to verify if the laboratory method precision (repeatability) is acceptable for these batches. However, laboratory duplicates analysed for all other batches indicate the laboratory method precision is acceptable.


Field duplicates were collected and analysed above the acceptable rate of one per 20 samples. Data generated for the analyses of soil field duplicates indicate an acceptable degree of precision (repeatability) in the laboratory methodology and minimal variation of target compounds within the sample matrices. Although some variations were observed, these are generally likely due to sample heterogeneity and low analyte concentrations exaggerating the RPD values. The auditor considers that the precision (repeatability) of the data reported is acceptable.


Field triplicates were collected and analysed above the acceptable rate of one per 20 samples. Data generated for the analyses of soil field triplicates indicate an acceptable degree of precision (repeatability) between the laboratory methodologies and minimal variation of target compounds within the sample matrices. Although some variations were observed, these are generally likely due to sample heterogeneity, low analyte concentrations exaggerating the RPD values and variations in laboratory analytical techniques. The auditor considers that the precision (repeatability) of the data reported is acceptable.



Laboratory duplicates were not undertaken for all secondary laboratory sample batches. Laboratory duplicates were generally undertaken at a rate of 10% for primary sample batches and all results were generally within the acceptable limits. Sufficient matrix spike and surrogate recoveries were also reported.


The majority of standard laboratory LORs for soil analyses were below the adopted criteria outlined in Section 6 (provided in Table 1) and are considered acceptable, with the following exceptions. The LORs for benzene, TCE, PCE and cis-1,2-DCE are greater than the adopted guidelines. These exceptions are discussed in Section 8.5.2.





64 43512483/R001/A

Post Phase 2 Environmental Site Assessment (Coffey, 2008c)

Table 8-8 Analytical Data Validation - Post Phase 2 ESA (Coffey, 2008c)


Auditor Comments








The interpretive quality control reports for the ALS sample batches were not provided by Coffey, therefore the Auditor was not able to verify that samples were analysed within recommended holding times for all samples collected. However, the laboratory reports were generally issued within a week of receiving the samples, therefore the samples are likely to have been analysed within holding times. LabMark laboratory batches reported holding time data which indicated samples were extracted and analysed within acceptable time frames.

Blank Monitoring All laboratory method blank, equipment blank, field blank and trip blank results were reported below the laboratory limits of reporting for the analytes tested, with the exception of the following: • All soil rinsate and field blanks reported low concentrations of chloroform; • One soil field blank also reported a low concentration of cadmium; • Two groundwater rinsate blanks and two field blanks reported low concentrations of

chloroform; and • One groundwater rinsate blank and one field blank reported low concentrations of

ferric iron, nitrate and nitrogen. Discussions between Coffey and the laboratory, ALS, confirm that the deionised water supplied by the laboratory for the blank samples contained impurities. Coffey also noted that soil and groundwater samples collected on the same day as the relevant blank samples reported concentrations of chloroform, cadmium and ferric iron below the laboratory limit of reporting. Concentrations of nitrate and nitrogen were detected in groundwater samples at several orders of magnitude higher than the levels observed in the contaminated rinsate and field blank samples. All other samples collected were reported at concentrations less than the laboratory limits of reporting. It is unlikely that cross contamination occurred. The Auditor accepts this explanation and does not consider the quality of the soil or groundwater samples have been adversely affected.



43512483/R001/A 65


Auditor Comments

Data Precision


Laboratory duplicates were not reported by secondary laboratory, LabMark. The Auditor is therefore unable to verify if the laboratory method precision (repeatability) is acceptable for these batches. However, laboratory duplicates analysed by the primary laboratory, ALS, indicate the laboratory method precision is acceptable.


Field duplicates were collected and analysed above the acceptable rate of one per 20 samples for groundwater, however, insufficient field duplicates were analysed for the soil sampling program. Two soil field duplicates were required, however, due to a mix up with samples, only one was analysed. Given the extensive history of soil sampling undertaken at the site and the similarity in results with previous investigations, the Auditor is satisfied that sufficient field duplicates were analysed. Data generated for the analyses of soil and groundwater field duplicates indicate an acceptable degree of precision (repeatability) in the laboratory methodology and minimal variation of target compounds within the sample matrices. Although some variations were observed, these are generally likely due to sample heterogeneity (soils) and low analyte concentrations exaggerating the RPD values. The auditor considers that the precision (repeatability) of the data reported is acceptable.


Field triplicates were collected and analysed at or above the acceptable rate of one per 20 samples for soil and groundwater. Data generated for the analyses of soil field triplicates indicate an acceptable degree of precision (repeatability) between the laboratory methodologies and minimal variation of target compounds within the sample matrices. Although some variations were observed, these are generally likely due to sample heterogeneity (soils), low analyte concentrations exaggerating the RPD values and variations in laboratory analytical techniques. The auditor considers that the precision (repeatability) of the data reported is acceptable.



Laboratory duplicates were generally undertaken at a rate of 10% and all results were within the acceptable limits. Sufficient matrix spike recoveries were also reported. The secondary laboratory, LabMark, however, did not report any laboratory QC data, therefore the Auditor is unable to verify the frequency of laboratory control measurements for those batches.


The majority of standard laboratory LORs for soil and groundwater analyses were below the adopted criteria outlined in Section 6 (provided in Tables 1 and 2) and are considered acceptable, with the following exceptions for soil and groundwater. The LORs for benzene, TCE, PCE and cis-1,2-DCE for soil samples are greater than the adopted guidelines. The LORs for a range of metals (secondary laboratory only), PAHs and chlorinated hydrocarbons, and nitrate and nitrite for groundwater samples are greater than the adopted guidelines. These exceptions are discussed in Section 8.5.2.





66 43512483/R001/A

Annual Groundwater Monitoring Event (Coffey, 2009a)

Table 8-9 Analytical Data Validation - Annual GME (Coffey, 2009a)


Auditor Comments






During sampling, field samples were handled and preserved in accordance with AS4482.1-2005 and EPA 441.7-2000. The sample temperature was either noted on the COC or marked as appropriately chilled.


The interpretive quality control reports for the ALS sample batches were not provided by Coffey, therefore the Auditor was not able to verify that samples were analysed within recommended holding times for all samples collected. However, the laboratory reports were generally issued within one to two weeks of receiving the samples, therefore the samples are likely to have been analysed within holding times. LabMark laboratory batches reported holding time data which indicated samples were extracted and analysed within acceptable time frames.

Blank Monitoring All laboratory method blank, equipment blank, field blank and trip blank results were reported below the laboratory limits of reporting for the analytes tested, with the exception of one rinsate blank which reported a low concentration of phenol. Only one groundwater sample collected on the same day as this rinsate blank reported a similar phenol concentration. Both concentrations are below the relevant GWQOs and the Auditor does not consider the quality of the groundwater samples have been adversely affected.

Data Precision


Laboratory duplicates analysed by the primary laboratory, ALS, indicate the laboratory method precision is acceptable. Laboratory duplicates were not reported by the secondary laboratory, LabMark. The Auditor is therefore unable to verify if the laboratory method precision (repeatability) is acceptable for these batches.


Field duplicates were collected and analysed above the acceptable rate of one per 20 samples for groundwater. Data generated for the analyses of field duplicates indicate an acceptable degree of precision (repeatability) in the laboratory methodology and minimal variation of target compounds within the sample matrices. Although some variations were observed, these are generally likely due to low analyte concentrations exaggerating the RPD values. The auditor considers that the precision (repeatability) of the data reported is acceptable.


Field triplicates were collected and analysed above the acceptable rate of one per 20 samples for groundwater. Data generated for the analyses of soil field triplicates indicate an acceptable degree of precision (repeatability) between the laboratory methodologies and minimal variation of target compounds within the sample matrices. One exception is the TDS results for MW2 and field triplicate QC5. Given the TDS value for MW2 is similar to that reported in previous monitoring rounds, the triplicate result is considered to be anomalous. The auditor considers that the precision (repeatability) of the data reported is acceptable.



43512483/R001/A 67


Auditor Comments



Laboratory duplicates were generally undertaken at a rate of 10% and all results were within the acceptable limits. Sufficient matrix spike recoveries were also reported. The secondary laboratory, LabMark, however, did not report any laboratory QC data, therefore the Auditor is unable to verify the frequency of laboratory control measurements for those batches.


The majority of standard laboratory LORs for groundwater analyses were below the adopted criteria outlined in Section 6 (provided in Table 2) and are considered acceptable, with the following exceptions. The LORs for a range of metals (secondary laboratory only), PAHs, chlorinated hydrocarbons and OCP’s are greater than the adopted guidelines. These exceptions are discussed in Section 8.5.2.



2009 Post Phase 2 Environmental Site Assessment (Coffey, 2009c)

Table 8-10 Analytical Data Validation – 2009 PP2 ESA (Coffey, 2009c)


Auditor Comments








The interpretive quality control reports for the ALS sample batches were not provided by Coffey, therefore the Auditor was not able to verify that samples were analysed within recommended holding times for all samples collected. However, the laboratory reports were generally issued within one week of receiving the samples, therefore the samples are likely to have been analysed within holding times. LabMark laboratory batches reported holding time data which indicated samples were extracted and analysed within acceptable time frames.

Blank Monitoring All laboratory method blank, equipment blank, field blank and trip blank results were reported below the laboratory limits of reporting for the analytes tested.



68 43512483/R001/A


Auditor Comments

Data Precision


Laboratory duplicates were not reported by the secondary laboratory, LabMark. The Auditor is therefore unable to verify if the laboratory method precision (repeatability) is acceptable for these batches. However, laboratory duplicates analysed by the primary laboratory, ALS, indicate the laboratory method precision is acceptable.


Field duplicates were collected and analysed above the acceptable rate of one per 20 samples for soil and groundwater. Data generated for the analyses of field duplicates indicate an acceptable degree of precision (repeatability) in the laboratory methodology and minimal variation of target compounds within the sample matrices. Although some variations were observed, these are generally likely due to low analyte concentrations exaggerating the RPD values. The auditor considers that the precision (repeatability) of the data reported is acceptable.


Field triplicates were collected and analysed above the acceptable rate of one per 20 samples for soil and groundwater. Data generated for the analyses of soil and groundwater field triplicates indicate an acceptable degree of precision (repeatability) between the laboratory methodologies and minimal variation of target compounds within the sample matrices. The auditor considers that the precision (repeatability) of the data reported is acceptable.



Laboratory duplicates were generally undertaken at a rate of 10% and all results were within the acceptable limits. Sufficient matrix spike recoveries were also reported.


The majority of standard laboratory LORs for soil and groundwater analyses were below the adopted criteria outlined in Section 6 (provided in Tables 1 and 2) and are considered acceptable, with the following exceptions for soil and groundwater. The LORs for benzene, TCE, PCE and cis-1,2-DCE for soil samples are greater than the adopted guidelines. The LORs for a range of metals (secondary laboratory only), PAHs and chlorinated hydrocarbons, and nitrate and nitrite for groundwater samples are greater than the adopted guidelines. These exceptions are discussed in Section 8.5.2.





43512483/R001/A 69

Groundwater Monitoring Event (Coffey, 2010a)

Table 8-11 Analytical Data Validation - GME (Coffey, 2010a)


Auditor Comments

Anomalous Results The reported concentrations of sulphate at MW7 and MW11 exceeded the laboratory-determined TDS concentrations. Coffey discussed this anomaly with the laboratory which identified that there was potential for sulphate concentrations to be overestimated, given the method used for the determination (ICP analysis followed by a conversion of sulphur concentration to sulphate concentrations). The Auditor requested a more precise method for analysing sulphate was used in subsequent GMEs.







The interpretive quality control reports for the ALS sample batches were not provided by Coffey, therefore the Auditor was not able to verify that samples were analysed within recommended holding times for all samples collected. However, the laboratory reports were generally issued within one week of receiving the samples, therefore the samples are likely to have been analysed within holding times. LabMark laboratory batches reported holding time data which indicated samples were extracted and analysed within acceptable time frames.

Blank Monitoring The Quality Control reports for the ALS sample batches were not provided by Coffey, therefore the Auditor was not able to verify that laboratory method blanks were reported below the laboratory limits of reporting for the analytes tested. Equipment blank, field blank and trip blank results were reported below the laboratory limits of reporting for the analytes tested.

Data Precision


The Quality Control reports for the ALS sample batches were not provided by Coffey , and laboratory duplicates were not reported by secondary laboratory, LabMark. The Auditor is therefore unable to verify if the laboratory method precision (repeatability) is acceptable for these batches.




Field triplicates were collected and analysed above the acceptable rate of one per 20 samples for groundwater. Data generated for the analyses of field triplicates indicate an acceptable degree of precision (repeatability) between the laboratory methodologies and minimal variation of target compounds within the sample matrices. The auditor considers that the precision (repeatability) of the data reported is acceptable.



70 43512483/R001/A


Auditor Comments



Data for laboratory duplicates was not provided by Coffey, therefore the Auditor was unable to verify that the frequency of analysis was sufficient. Data was not provided for the primary laboratory, ALS, therefore the Auditor is unable to verify the frequency of laboratory control measurements for those batches. Given the groundwater analytical results are consistent with previous rounds of sampling, it appears the laboratory results are reliable. Sufficient, and acceptable, laboratory quality control data was provided for the secondary laboratory, LabMark.





Further Tank Excavation Assessment Report (Coffey, 2010c)

Table 8-12 Analytical Data Validation - Further TEA (Coffey, 2010c)


Auditor Comments








The interpretive quality control reports for the ALS sample batches indicated that samples were analysed within recommended holding times for all samples collected. LabMark laboratory batches reported holding time data which indicated samples were extracted and analysed within acceptable time frames.




43512483/R001/A 71


Auditor Comments

Data Precision


Laboratory duplicates were not reported by secondary laboratory, LabMark. The Auditor is therefore unable to verify if the laboratory method precision (repeatability) is acceptable for these batches. However, laboratory duplicates analysed by the primary laboratory, ALS, indicate the laboratory method precision is acceptable.




Field triplicates were collected and analysed above the acceptable rate of one per 20 samples for groundwater. Data generated for the analyses of soil field triplicates indicate an acceptable degree of precision (repeatability) between the laboratory methodologies and minimal variation of target compounds within the sample matrices. The auditor considers that the precision (repeatability) of the data reported is acceptable.





The majority of standard laboratory LORs for soil analyses were below the adopted criteria outlined in Section 6 (provided in Table 1) and are considered acceptable, with the following exceptions: the LORs for benzene, TCE, PCE and cis-1,2-DCE for soil samples are greater than the adopted guidelines. These exceptions are discussed in Section 8.5.2.





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Interim Groundwater Monitoring Event (Coffey, 2010d)

Table 8-13 Analytical Data Validation - Interim GME (Coffey, 2010d)


Auditor Comments

Anomalous Results Concentrations of sulphate in groundwater were reported to be higher than chloride concentrations in the majority of samples. There are some apparently anomalous sulphate concentrations where sulphate represents an unusually high proportion of the TDS (in some cases, the sulphate results were higher than the TDS results) where chloride would normally be expected to be the major anion in groundwater in this aquifer. The laboratory was asked to confirm the results and reanalyse using a more precise method (ion chromatography), however, the original results were confirmed. Laboratory personnel suggested that there is possibly another source of sulphate in these samples that is not incorporated into the TDS determination. The Auditor believes the results are anomalous and the site is not the source of the elevated sulphate concentrations. However, he has conservatively adopted the results.







The interpretive quality control reports for the ALS sample batches indicated that samples were analysed within recommended holding times for all samples collected. LabMark laboratory batches reported holding time data which indicated samples were extracted and analysed within acceptable time frames.


Data Precision


Laboratory duplicates analysed by the primary laboratory, ALS, indicate the laboratory method precision is acceptable. Laboratory duplicates were not reported by secondary laboratory, LabMark. The Auditor is therefore unable to verify if the laboratory method precision (repeatability) is acceptable for these batches.




Field triplicates were collected and analysed above the acceptable rate of one per 20 samples for groundwater. Data generated for the analyses of soil field triplicates indicate an acceptable degree of precision (repeatability) between the laboratory methodologies and minimal variation of target compounds within the sample matrices. The auditor considers that the precision (repeatability) of the data reported is acceptable.



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Auditor Comments








8.5.2 Limits of Reporting

Soil The analytical limits of reporting were sufficiently low to enable a meaningful comparison between sample results and the Auditors adopted soil criteria (Table 1 – attached) for the constituents of potential concern.

For trichloroethylene TCE), the Canadian Environmental Quality Guideline of 0.05 mg/kg (taken from CCME Canada-wide Standards for Petroleum Hydrocarbons (PHC) in Soil (2008)) has been adopted as the screening criterion for maintenance of ecosystems and production of food, flora and fibre. The standard LOR for TCE used in the investigation (0.5 mg/kg) is above this screening criterion. As all soil results reported concentrations of TCE below the laboratory limit of reporting for all phases of work and the fact that virtually all soil at the site has been excavated to between 1.8 and 5m bgs the Auditor does not consider the LOR to affect the characterisation of the site.

Groundwater As outlined in Section 8.5.1 above, a number of standard laboratory LORs were greater than the adopted guidelines, as summarised below:

• Berylium (LOR 0.01 mg/L) above the adopted GWQO for the beneficial use Maintenance of Ecosystems (0.00013 mg/L) (secondary laboratory, LabMark, only);

• Cadmium (LOR 0.001 mg/L) above the adopted GWQO for the beneficial use Maintenance of Ecosystems (0.0002 mg/L) (secondary laboratory, LabMark, only);

• Mercury (LOR 0.001 mg/L) above the adopted GWQO for the beneficial use Maintenance of Ecosystems (0.0006 mg/L) (secondary laboratory, LabMark, only);

• Chromium (LOR 0.005 mg/L) above adopted GWQO for the beneficial use Maintenance of Ecosystems (0.001 mg/L) (secondary laboratory, LabMark, only);

• Copper (LOR 0.005 mg/L) above adopted GWQO for the beneficial use Maintenance of Ecosystems (0.0014 mg/L) (secondary laboratory, LabMark, only);



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• Lead (LOR 0.005 mg/L) above adopted GWQO for the beneficial use Maintenance of Ecosystems (0.0034 mg/L) (secondary laboratory, LabMark, only);

• PAH (anthracene) (LOR 0.0005 mg/L (primary laboratory) and 0.001 mg/L (secondary laboratory)) above the adopted GWQO for the beneficial use Maintenance of Ecosystems (0.0004 mg/L);

• PAHs (benzo(a)anthracene, benzo(b)fluoranthene and indeno(1,2,3-c,d)pyrene) (LOR 0.0005 mg/L (primary laboratory) and 0.001 mg/L (secondary laboratory)) above the adopted GWQOs for the beneficial uses Stockwatering (0.000029 mg/L) and Primary Contact Recreation. (0.00029 mg/L);

• PAH (benzo(a)pyrene) (LOR 0.0005 mg/L (primary laboratory) and 0.001 mg/L (secondary laboratory)) above adopted GWQOs for the beneficial uses Maintenance of Ecosystems (0.0002 mg/L), Stockwatering (0.00001 mg/L) and Primary Contact Recreation. (0.0001 mg/L);

• PAH (benzo(k)fluoranthrene) (LOR 0.0005 mg/L (primary laboratory) and 0.001 mg/L (secondary laboratory)) above the adopted GWQO for the beneficial use Stockwatering (0.00029 mg/L);

• PAHs (dibenz(a,h)anthracene) (LOR 0.0005 mg/L (primary laboratory) and 0.001 mg/L (secondary laboratory)) above adopted GWQOs for the beneficial uses Stockwatering (0.0000029 mg/L) and Primary Contact Recreation. (0.000029 mg/L);

• PAH (phenanthrene) (LOR 0.0005 mg/L (primary laboratory) and 0.001 mg/L (secondary laboratory)) above the adopted GWQO for the beneficial use Maintenance of Ecosystems (0.0002 mg/L);

• PAH (naphthalene) (LOR 0.0005 mg/L (primary laboratory) and 0.001 mg/L (secondary laboratory)) above the adopted GWQO for the beneficial use Stockwatering (0.00014 mg/L);

• Phenol (2-chlorophenol) (LOR 0.01 mg/L) above the GWQO criterion for the beneficial use Primary Contact Recreation (0.001 mg/L) (secondary laboratory, LabMark, only);

• Phenol (pentachlorophenol) (LOR 0.01 mg/L) above the adopted GWQO for the beneficial use Stockwatering (0.009 mg/L) (secondary laboratory, LabMark, only);

• Phenol (2-nitrophenol) (LOR 0.01 mg/L) above the adopted GWQO for the beneficial use Maintenance of Ecosystems (0.002 mg/L) (secondary laboratory, LabMark, only);

• Carbon tetrachloride (LOR 0.005 mg/L) above the adopted GWQO for the beneficial use Stockwatering (0.003 mg/L);

• Trichloroethylene (LOR 0.005 mg/L) above the adopted GWQO for the beneficial use Stockwatering (0.002 mg/L);

• Vinyl chloride (LOR 0.005 mg/L) above the adopted GWQOs for the beneficial uses Stockwatering (0.0003 mg/L) and Primary Contact Recreation (0.003 mg/L);

• 1,2,4-trichlorobenzene (LOR 0.005 mg/L) above the adopted GWQO for the beneficial use Stockwatering (0.0023 mg/L);

• 1,2,3,4 tetrachlorobenzene (LOR 0.005 mg/L) above the adopted GWQO for the beneficial use Maintenance of Ecosystems (0.002 mg/L);

• 1,2,3,5 tetrachlorobenzene (LOR 0.005 mg/L) above the adopted GWQO for the beneficial use Maintenance of Ecosystems (0.003 mg/L);

• 1,2,4,5 tetrachlorobenzene (LOR 0.005 mg/L) above the adopted GWQO for the beneficial uses Stockwatering (0.0011 mg/L);



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• Hexachlorobenzene (LOR 0.005 mg/L) above the adopted GWQO for the beneficial use Maintenance of Ecosystems (0.00005 mg/L);

• OCPs (endosulfan, lindane, heptachlor, heptachlor epoxide, aldrin, DDE, dieldrin, DDT, endrin, methoxychlor, chlordane, endosulfan alpha, endosulphan beta) (LOR 0.0005 mg/L (primary laboratory) and 0.001 mg/L (secondary laboratory)) above adopted GWQOs for the beneficial use Maintenance of Ecosystems (0.0000002 – 0.0002 mg/L);

• OCPs (heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin) (LOR 0.0005 mg/L (primary laboratory) and 0.001 mg/L (secondary laboratory)) above adopted GWQOs for the beneficial use Stockwatering (0.0003 – 0.0006 mg/L);

• PCBs (aroclors 1016, 1232, 1242, 1248, 1254) (LOR 0.001 mg/L) above adopted GWQOs for the beneficial use Maintenance of Ecosystems (0.000001 – 0.0006 mg/L);

• PCBs (aroclors 1016, 1221, 1232, 1242, 1248, 1254, 1260) (LOR 0.001 mg/L) above adopted GWQOs for the beneficial use Stockwatering (0.0000068 – 0.00096 mg/L); and

• PCBs (total PCBs and aroclors 1221, 1232, 1242, 1248, 1254, 1260) (LOR 0.001 mg/L) above adopted GWQOs for the beneficial use Primary Contact Recreation (0.000068 – 0.00034 mg/L).

Lower LORs for metals (beryllium, cadmium, mercury, chromium, copper and lead) and phenols (2-chlorophenol, 2-nitrophenol and pentachlorophenol) are able to be achieved by Australian laboratories, which would meet the adopted GWQOs. The LORs for these species were only reported above the adopted guidelines by the secondary laboratory. Therefore, as the primary laboratory reported sufficiently low LORs, the Auditor is satisfied that these species have been assessed appropriately.

Australian laboratories are able to determine the above listed PAHs to an ultra trace level (0.005- 0.1 µg/L); these reduced LORs would be generally below the adopted GWQOs. A review of the historical use of the Audit site indicates sources of PAHs and phenols may include historic filling of the site. Total PAH concentrations were reported up to 131 mg/kg in the surface fill material (the majority of fill material was subsequently removed during site remedial works) and less than the LOR at depth in the natural soils. The Auditor does not consider the LORs for these PAHs to affect the characterisation of the site for the following reasons:

• Groundwater criteria for Maintenance of Ecosystems apply at the point of discharge (and not at the site itself), in this case, Merri Creek, situated 550m southeast of the site;

• As discussed in Section 6, ANZECC (2000) defaults to the NHMC (2004) human health drinking water guidelines where no guideline is given in ANZECC for stockwatering. The NHMRC (2004) objectives have been derived using human health specific exposure scenarios (e.g. 70 years exposure, consuming 2L of water per day) and on the basis of an unacceptable probability of an increased incidence of cancer (in a human population) caused by the exposure and therefore is considered to be represent conservative criteria for stock; and

• A review of the registered groundwater bore search indicates that groundwater use in the area is for groundwater investigation purposes and is not utilised for stockwatering or primary contact recreation. Due to the land use and hydrogeological setting of the Audit site, the beneficial uses Stockwatering and Primary Contact Recreation are considered by the Auditor to be unlikely to be realised.



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Australian laboratories are able to determine the above listed OCPs to an ultra trace level (0.005-0.1 µg/L); the high end of this range is generally still above the adopted GWQOs for the beneficial use Maintenance of Ecosystems. OCPs may have been applied at the site for insect control, however there is no explicit evidence of the use or storage of pesticides on site. The Auditor did not consider the elevated LORs applied for OCP analysis at the site to affect the characterisation of the groundwater at the site for the following reasons:

• OCPs were reported below the laboratory LORs in the soil, therefore indicating a lower likelihood of their presence in groundwater;

• Groundwater criteria for Maintenance of Ecosystems apply at the point of discharge (and not at the site itself);


• A review of the registered groundwater bore search indicates that groundwater use in the area is for groundwater investigation purposes and is not utilised for stockwatering. Due to the land use and hydrogeological setting of the Audit site, the beneficial use Stockwatering is considered by the Auditor to be unlikely to be realised.

Laboratory LORs were above the adopted groundwater criteria (Maintenance of Ecosystems, Stockwatering and/or Primary Contact Recreation) for carbon tetrachloride, trichloroethylene, vinyl chloride, 1,2,4-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene and hexachlorobenzene. A review of the historical site use of the Audit site indicates that these chlorinated hydrocarbons are unlikely to have been used at the site and have not been detected in the groundwater at the site. The Auditor does not consider these elevated LORs to affect the characterisation of the site for the following reasons:

• As discussed in Section 6, ANZECC (2000) defaults to the NHMC (2004) human health drinking water guidelines where no guideline is given in ANZECC for Stockwatering. The NHMRC (2004) objectives have been derived using human health specific exposure scenarios (e.g. 70 years exposure, consuming 2L of water per day) and on the basis of an unacceptable probability of an increased incidence of cancer (in a human population) caused by the exposure and therefore is considered to be represent conservative criteria for stock; and

• A review of the registered groundwater bore search indicates that groundwater use in the area is for groundwater investigation purposes and is not utilised for stockwatering or primary contact recreation. Due to the land use and hydrogeological setting of the Audit site, the beneficial uses stockwatering and primary contact recreation are considered by the Auditor to be unlikely to be realised.



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Laboratory LORs were above the adopted groundwater criteria (Maintenance of Ecosystems, Stockwatering and/or Primary Contact Recreation) for PCBs (total PCBs and aroclors 1016, 1221, 1232, 1242, 1248, 1254, 1260). Australian laboratories are able to determine the above listed PCBs to an ultra trace level (0.000002-0.1 µg/L); these low end of this range would be generally below the adopted groundwater criteria.. A review of the historical site use of the Audit site indicates that these chlorinated hydrocarbons are unlikely to have been used at the site and have not been detected in the groundwater at the site. The Auditor does not consider these elevated LORs to affect the characterisation of the site for the following reasons:

• OCPs were reported below the laboratory LORs in the soil, therefore indicating a lower likelihood of their presence in groundwater;

• Groundwater criteria for maintenance of ecosystems apply at the point of discharge (and not at the site itself);


• A review of the registered groundwater bore search indicates that groundwater use in the area is for groundwater investigation purposes and is not utilised for stockwatering or primary contact recreation. Due to the land use and hydrogeological setting of the Audit site, the beneficial uses stockwatering and primary contact recreation are considered by the Auditor to be unlikely to be realised.

8.6 Auditor’s Overall Comment on Data Quality On the basis of the analytical data validation procedure employed, the overall quality of the analytical data produced (with the limitations discussed above) is considered to be of acceptable standard for interpretive use. The variable concentrations within the sample matrices observed through replicate analysis is expected in soil matrices, particularly those characterised as fill material.

As a result, after also considering URS verification sampling at the site (discussed in Section 9.5), the Auditor is of the opinion that the data produced by the sampling and analytical program are satisfactory and enable him to be satisfied as to the environmental condition of the site and make conclusions about the suitability of the site for use.


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9

9 Environmental Condition of Site

9.1 Imminent Environmental Hazards The Auditor is not aware of any imminent environmental hazards that are associated with the subject site.

9.2 Site Condition Prior to Remediation (1998) The following describes the environmental condition of the site prior to the commencement of this Audit in 2008 and prior to remediation. Prior to the site being decommissioned and remediated, the only known site investigation to have been undertaken at the site was by Handex in 1998 (and completed in 2002). At that time, the site was a closed service station with all infrastructure remaining on site (with the exception of the petrol dispensing pumps). The condition of the site prior to remedial works in 2003 is therefore limited to the 1998 site assessment (Handex, 2002). Figure 2 shows the site features at the commencement of the Audit and Figure 5 illustrates the soil and groundwater well locations.

9.2.1 Soil Prior to the site being decommissioned and remediated, it was largely covered with concrete pavement with small garden bed areas and site infrastructure included a salesroom, workshop, toilet block, four known USTs and associated underground pipes. The nine dispensing pumps had been removed. Nineteen grid point soil bores were drilled in 1998 and all encountered concrete up to 0.1m thick, underlain by fill (sandy, gravely clay with some brick fragments) to a typical depth of 0.4 m bgs. Brown, clay fill material with some sand and brick fragments was encountered to a depth of 3.5 m bgs at MW1, located a few metres to the north of UST 7.

Fill The historic fill at the site typically comprised green/black sandy clay of uneven texture with minor bricks and gravel present. Samples were analysed for a limited suite of analytes including TPH, BTEX, lead, and two samples were also analysed for heavy metals. All samples reported concentrations below the adopted investigation levels.

Natural Soil As per the fill samples, samples were analysed for a limited suite of analytes including TPH, BTEX, and lead. Benzene concentrations were reported above the adopted investigation levels at NGP16 at 1.8 and 3.2 m bgs, located in the central northern boundary of the site (refer to Figure 5). Concentrations of lead exceeded the adopted investigation levels at NGP3-0.4 (located close to the south eastern corner) and NGP11-0.3 (located close to the south western corner). All other samples within the natural soil reported concentrations below the adopted criteria.

9.2.2 Perched Water During soil sampling, perched water was encountered at NGP14 (located close to the north western corner of the site) at 1.2 m bgs (refer to Figure 5). No other perched water was encountered during the investigation. A sample of the perched water identified concentrations of TPH and BTEX, with TPH C10-C36 concentration exceeding the adopted groundwater quality objectives.



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9.2.3 Groundwater One groundwater monitoring well, MW1, was installed at the site prior to remediation by Handex in 1998 (Handex, 2002). MW1 was located in the centre of the site, between the southern tank farm and bowser island (refer to Figure 5). The groundwater was analysed for TPH, BTEX, and lead with all concentrations reported either below the laboratory LORs or the adopted groundwater quality objectives (GWQOs).

A full onsite assessment of groundwater was not undertaken prior to site decommissioning and remedial activities due to the planned extensive nature of infrastructure removal and large excavations. Four offsite groundwater monitoring wells were installed in February 2008, prior to the completion of remedial activities. Two wells (MW1 and MW2) were located to the north of the site on the footpath of Arthurton Road, and two wells (MW3 and MW4) were located to the south of the site on the footpath of Auburn Avenue.

The monitoring wells were sampled and analysed for a range of analytes, including TPH, BTEX, PAHs, phenols, heavy metals, VHCs, and natural attenuation parameters. All concentrations were reported below the laboratory LORs or adopted GWQOs, with the following exceptions:

• Groundwater from MW1 contained concentrations of cadmium (0.2 μg/L), copper (2 μg/L), nickel (185 μg/L) and zinc (27 μg/L) above the adopted maintenance of ecosystems (MoE) GWQOs;

• Groundwater from MW2 contained concentrations of copper (9 μg/L), lead (5 μg/L), nickel (31 μg/L) and zinc (16 μg/L) above the MoE GWQOs;

• Groundwater from MW3 contained concentrations of cadmium (0.2 μg/L), total chromium (2 μg/L), copper (4 μg/L), nickel (8 μg/L), zinc (9 μg/L) and nitrate (8.97 mg/L) above the MoE GWQOs; and

• Groundwater from MW4 contained concentrations of copper (2 μg/L), nickel (6 μg/L) and zinc (16 μg/L) above the MoE GWQOs.

9.3 Infrastructure Decommissioning/Site Remediation (2003 – 2010)

9.3.1 Soil Decommissioning and remediation of the site comprised removal of primary and secondary sources of contamination, including eleven USTs, bowser island, fill points, associated fuel lines (fill, suction and vents), hydraulic hoist, workshop, TIT and associated soils in various phases between 2003 and 2010. Plans of the remediation excavations are provided as Figure 4 of ITE (2004), Figures 3a to 3d of Coffey (2007) and Figures 11 to 20 of Coffey (2010e). Figure 6 illustrates the excavation extents in 2003, Figures 7a to 7d illustrates the excavation extents in 2005 and Figure 8 illustrates the extent of excavations across the site from 2007 to 2010. Figure 9 illustrates the extent of excavation relating to the removal of three USTs in the north east of the site in 2010. Excavation of historical fill in the north east of the site (during the removal of the three USTs) was limited by the close proximity of the roads, major intersection and underground services. Residual historical fill remains in this area.

The entire site, with the exception of a small area on the north western boundary and areas covered by the footpath along the eastern and northern boundaries, were excavated to depths between 1.8 and 5.0 m bgs.



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Excavations across the site were extended until soil validation samples returned analytical results below the criteria adopted by the site assessor and excavations were considered validated. The concentrations of various metals in soil (including vanadium (mostly), arsenic, barium, copper, manganese and nickel) were reported above the adopted IL for maintenance of ecosystems, however, similar concentrations were reported across the site and did not exceed the adopted human health criteria and were considered to be representative of background concentrations.

Soil excavated from the site contained concentrations of TPH C6-C9 that were generally below the LOR and up to a maximum of 322 mg/kg in Excavation C in the area of the former bowser island in the centre of the site. The maximum concentrations of TPH C10-C36 (1,110 mg/kg) and Total PAHs (130 mg/kg) were identified in Excavation C in the area of the former hoist pit in the eastern portion of the site. The excavated soil was disposed to Hi Quality Sales Bulla or SITA Dandenong South.

Prior to 1 July 2007, approximately 1,848 m3 of stockpiled soil was disposed off-site in accordance with EPA Publication 448.1. 410 m3 was disposed as Contaminated Soil (Low Level) and 1,438 m3 as Fill Material (brick fill/stained/odorous).

After 1 July 2007, approximately 2,905 m3 of stockpiled soil was disposed off-site in accordance with EPA Publication 448.3. 120 m3 was disposed as Category B Contaminated Soil, 1,865 m3 as Category C Contaminated Soil and 920 m3 as Fill Material.

Approximately 41,000 L of water (surface water runoff) was removed during the soil validation works from open excavations. 2,000 L of oily water was also pumped from the three USTs prior to decommissioning. The water was classified and disposed off-site by an EPA licensed waste disposal contractor.

Excavations across the site were predominantly backfilled with 40 mm non-descriptive crushed rock (NDCR) sourced from Boral Quarries and High Quality Sales, Bulla. The quality of this material is discussed in Section 9.4.1 below.

9.3.2 Groundwater No direct groundwater remediation has been undertaken or is proposed for this site.

9.4 Final Condition of the Site

9.4.1 Soil All soil results have been compared against the adopted soil criteria for the beneficial uses of land at the site (refer to Section 6 and Table 1).

Soil results which exceed the adopted soil criteria for the beneficial uses of land at the site have been summarised in Table 3 (attached) and are discussed below.

Historical Fill Material Historical fill material, comprising gravelly, clayey sand, remains beneath the footpath at the northern and eastern areas of the site. The depth of fill ranges from approximately 0.4 m bgs in the east to 1.2 m bgs in the north. The fill material has been completely excavated across the remainder of the site. Analytical soil results for the remaining historical fill material indicates the following:



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• Concentrations of TPH C15-C36 exceeded the adopted soil criteria for Human Health – Low Density Residential (300 mg/kg) at two locations beneath the footpath on the northern site boundary; ExE_V21 (520 mg/kg at 1.5 m bgs) and ExE_V25 (390 mg/kg at 0.3 m bgs);

• Concentrations of benzo(a)pyrene exceeded the adopted soil criteria for Human Health – Low Density Residential (1 mg/kg) at four locations beneath the footpath in the north east corner of the site; ExE_V18 (1.6 mg/kg at 0.3 m bgs), ExE_V22 (1.3 mg/kg at 1.5 m bgs), ExE_V24 (1.9 mg/kg at 0.3 m bgs) and ExE_V25 (6.9 mg/kg at 0.3 m bgs);

• Concentration of benzo(a)pyrene exceeded the adopted soil criteria for Human Health – Public Open Space (2mg/kg), High Density Residential (4mg/kg) and commercial / industrial use (5mg/kg) at sample location ExE_V25 (6.9 mg/kg at 0.3 m bgs);

• Concentrations of Total PAHs exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (18 mg/kg), Human Health – Low Density Residential (20 mg/kg) and Public Open Space (40 mg/kg) at soil location ExE_V25 (73.2 at 0.3 m bgs), located beneath the footpath on the northern site boundary; and

• The concentration of zinc exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (200 mg/kg) at sample location ExE_V24 (281 mg/kg at 0.3 m bgs), located beneath the footpath on the northern site boundary.

Natural Soil Concentrations of TPH C6-C9 exceed the adopted soil criteria for Human Health - Low and High Density Residential (30 mg/kg) at three locations in the base of the former excavations; EW23 (55 mg/kg at 3.5 m bgs), EW25 (90 mg/kg at 3.5 m bgs) and TA-B2_6/6 (110 mg/kg at 3.5 m bgs). EW23 and EW25 were located within the initial ITE Excavation D (excavation for USTs 5 – 8 in the central portion of the site) (refer to Figure 6), while TA-B2 was located to the south east of UST 3 (refer to Figure 7c). The TPH C6-C9 concentrations for samples EW25 and TA-B2 also exceed the adopted soil criteria for Human Health – Public Open Space (60 mg/kg).

Concentrations of TPH C10-C14 exceed the adopted soil criteria for Maintenance of Ecosystems (150 mg/kg), Production of Food, Flora and Fibre (150 mg/kg), Human Health – Low Density Residential (150 mg/kg), Human Health – High Density Residential (600 mg/kg), Human Health – Public Open Space (300 mg/kg) and Human Health – Commercial/Industrial (260 mg/kg) at two locations in the base of the former excavations; EW23 (760 mg/kg) and EW25 (940 mg/kg).

The concentration of TPH C15-C36 exceeded the adopted soil criteria for Human Health – Low Density Residential (300 mg/kg) at soil location EXC-WW2 (465 mg/kg at 2 m bgs), located in the central portion of the site, to the south west of the bowser island.

The concentration of ethylbenzene exceeded the adopted soil criteria for Human Health – Low and High Density Residential (5.4 mg/kg) and Human Health – Public Open Space (10.8 mg/kg) for soil sample EW23 (21 mg/kg at 3.5 m bgs).

The concentration of benzo(a)pyrene exceeded the adopted soil criteria for Human Health – Low Density Residential (1 mg/kg) at soil location TA-N2 (1.99 mg/kg at 3.2 m bgs), located in the north east portion of the site, to the east of UST 3.

The concentration of Total PAHs exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (18 mg/kg) at soil location; EW25 (18.7 mg/kg at 3.5 m bgs).



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The concentration of arsenic exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (20 mg/kg) at sample location EXC-NW2 (22 mg/kg at 3 m bgs), located in the central portion of the site.

Concentrations of barium exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (300 mg/kg) at eleven locations across the site with concentrations ranging from 310 mg/kg (TB-EW21 at 0.5 m bgs) to 730 mg/kg (TB-B18 at 2.3 m bgs).

The concentration of copper exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (100 mg/kg) at sample location TB-WW6 (174 mg/kg at 0.5 m bgs), located on the northern portion of the western site boundary.

The concentration of manganese exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (500 mg/kg) at sample location TB-B29 (655 mg/kg at 1.6 m bgs), located on the western site boundary.

Concentrations of nickel exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (60 mg/kg) at five locations, with concentrations ranging from 62 mg/kg (MW8_6.0) to 87 mg/kg (TB-B29 at 1.6 m bgs). Sample locations were distributed across the entire site.

Concentrations of vanadium exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (50 mg/kg) at 44 locations, with concentrations ranging from 50 mg /kg (ExE_V15 at 1.5 m bgs) to 225 mg/kg (TB-NW6 at 1 m bgs). Sample locations were distributed across the entire site.

Imported Fill Material Excavations across the site were predominantly backfilled with 40 mm non-descriptive crushed rock (NDCR) sourced from Boral Quarries and High Quality Sales, Bulla. Soil validation results of the imported fill indicated that several samples reported concentrations of various heavy metals above the adopted soil criteria for the Maintenance of Ecosystems and Production of Food, Flora and Fibre. These concentrations were reported below the adopted NEPM human health criteria. The results indicated the following:

• Concentrations of arsenic exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (20 mg/kg) for three samples, with concentrations ranging from 20 mg/kg (IF-26) to 27 mg/kg (IF-35);

• The concentration of barium exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (300 mg/kg) for soil sample IF-46 (1,680 mg/kg);

• Concentrations of manganese exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (500 mg/kg) for sixteen samples, with concentrations ranging from 529 mg/kg (IF-8) to 1,300 mg/kg (IF-11);

• Concentrations of nickel exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (60 mg/kg) for two samples; IF-44 (94 mg/kg) and IF-46 (136 mg/kg); and

• Concentrations of vanadium exceeded the adopted soil criteria for Maintenance of Ecosystems and Production of Food, Flora and Fibre (50 mg/kg) for two samples; IF-1 (54 mg/kg) and IF-11 (52 mg/kg).



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A concentration of total chromium exceeded the adopted soil criteria for Human Health – Low Density Residential Use (100 mg/kg) for sample IF-44 (110 mg/kg).

A concentration of cobalt exceeded the adopted soil criteria for Human Health – Low Density Residential (100 mg/kg) and Public Open Space (200 mg/kg) for sample IF-46 (228 mg/kg).

9.4.2 Groundwater No direct groundwater remediation was undertaken at the site. Groundwater across the site was extensively assessed during and following the completion of soil remedial activities, with the installation and sampling of thirteen on-site groundwater monitoring wells and sampling of the four previously installed off-site wells.

Groundwater sampling events were undertaken in July 2008, September 2008, April/May 2009 (selected wells), November 2009, February 2010 (selected wells) and July 2010 (selected wells). Table 4 outlines the exceedances of the adopted GWQOs after soil remediation for the most recent sampling event. The following summarises the condition of the groundwater at and around the site:

• BTEX compounds were reported to be below the laboratory LORs for all rounds of monitoring with the exception of benzene in September 2008 and November 2009 at MW7 (4 ug/L and 3 ug/L respectively). The benzene concentration at MW7 in the latest round of monitoring in February 2010 was below the laboratory LOR of 1 ug/L;

• TPH C6-C9 concentrations were reported in a number wells, ranging from 30ug/L to 440ug/L, however no BTEX concentrations were identified. Review of the chromatograms indicated methyl tert-butyl ether (MTBE) may be present (resulting in the TPH C6-C9 concentrations reported), and was subsequently analysed for the first time in September 2008. MTBE has consistently been detected in monitoring wells MW5, MW6, MW8, MW9, MW10 and MW17 in concentrations ranging from 12 ug/L (MW6 in November 2009) to 434 ug/L (MW5 in November 2009). Concentrations of MTBE in excess of the adopted GWQOs (for Agriculture, Parks and Gardens and Primary Contact Recreation) were present in wells MW5, MW8, MW9 and MW10 in July 2010 (the Auditor notes that MW6 was decommissioned in February 2010 to enable the removal of USTs 9 to 11 in the north eastern corner of the site);

• Concentrations of TPH C10-C36 were reported in various wells for each GME, however, when silica gel cleanup was applied to sample extracts, TPH C10-C36 concentrations were reported below laboratory LORs, with the exception of MW3 (130 ug/L in November 2009), which is below the relevant GWQO (600ug/L);

• Analysis of heavy metals reported concentrations of cadmium (0.0002 to 0.0007 mg/L), copper (0.002 to 0.027 mg/L), nickel (0.013 to 0.356 mg/L) and/or zinc (0.008 to 0.146 mg/L) in excess of the adopted GWQOs for the beneficial use Maintenance of Ecosystems at various well locations on and off the site. Given the consistent nature of the metals concentrations identified across the site and up and down gradient of the site, it was considered that these metals were naturally occurring in the siltstone aquifer. In accordance with the SEPP (Groundwaters of Victoria), where naturally occurring background concentrations exceed the nominated GWQOs, the background concentrations become the objectives; and



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• Elevated sulphate concentrations in excess of the adopted GWQOs for beneficial uses including Stock Watering, Primary Contact Recreation, Buildings and Structures and Industrial Water Use were identified in monitoring wells MW7, MW10, MW11 and MW17 (see Table 4). The issues associated with the reported sulphate concentrations (in some cases exceeding the TDS concentrations) are discussed in Sections 8.5.1 and 10.2.3.

9.5 Auditor Verification Sampling During a site inspection by the Auditor’s assistant on 31 July 2008 during the Post Phase 2 ESA phase of works, a groundwater verification sample from offsite monitoring well, MW2, was collected and sent for analysis. During a site inspection by the Auditor and his assistant on 16 February 2010 during the Further Tank Excavation Assessment phase of works, a soil verification sample was collected from the UST 9-11 excavation.

The objectives of verification sampling by the Auditor were to:

• independently verify the data provided by the site assessor; • correlate the Auditor’s observations of the groundwater with independent analytical results; • to gain a clearer understanding of the nature and distribution of contaminants on site; and • to satisfy the Auditor that the data presented by the site assessor can be relied upon in order to

issue a Certificate or Statement of Environmental Audit.

The Auditor elected not to submit the soil sample for laboratory analysis as onsite observations of the excavation and the soil sample indicated there were no visual or olfactory signs of contamination. Therefore, the Auditor considered analysis of the soil sample would not add any value in gaining a clearer understanding of the condition of the site.

The groundwater sample was collected using the low-flow equipment used by the site assessor, Coffey Environments and forwarded to MGT for analysis of TPH, BTEX, PAHs, phenols, volatile chlorinated hydrocarbons, heavy metals, and natural attenuation parameters.

Groundwater sampling sheets and certificates of analysis are contained within Appendix G. The results were generally below the laboratory LORs with the exception of TPH C6-C9, metals and natural attenuation parameters. A TPH C6-C9 concentration of 300 μg/L was reported, however, there are no applicable GWQOs for TPH C6-C9 in groundwater. All other analyte concentrations were reported below the adopted GWQOs, with the exception of cobalt (0.02 μg/L), iron (0.47 μg/L), nickel (0.025 μg/L) and zinc (0.011 μg/L) which all exceeded the adopted GWQO for Maintenance of Ecosystems. The concentration of iron also exceeded the Primary Contact Recreation GWQO.

A comparison of the Auditor verification sample results with the site assessor results indicates a good correlation between concentrations. This, together with a detailed review of the site assessors data, satisfies the Auditor that the data produced by the site assessor is acceptable and enables him to make conclusion about the suitability of the site for use. The results of the verification samples have been considered in combination with the primary data provided to the Auditor by the site assessor.


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10

10 Harm, Detriment or Risk to Beneficial Uses of the Site

10.1 Soil The beneficial uses of land associated with the proposed and potential uses of the site are outlined in Section 6.2. The environmental condition of the site after remediation is described in Sections 9.3 and 9.4. An assessment of the harm, detriment, or risk to beneficial uses of the site posed by the condition of the site follows.

10.1.1 Maintenance of Ecosystems and Production of Food, Flora and Fibre The concentrations of zinc and Total PAHs in historical fill material beneath the footpath near the northern site boundary (sample locations ExE_V24 and ExE_V25 respectively) exceeds the adopted soil criteria for beneficial uses of Maintenance of Ecosystems and Production of Food, Flora and Fibre. In the Auditor’s opinion, the concentrations of zinc and Total PAHs above the adopted soil criteria at these locations in historical fill represent a potential for harm, detriment or risk to the beneficial use Maintenance of (modified) Ecosystems and Production of Food, Flora and Fibre associated with low density residential use (ie. including gardens / accessible soil), high density residential use and public open space where soil is accessible. Due to the lower sensitivity associated with maintenance of (highly modified) ecosystems, the Auditor does not consider these exceedences of the adopted soil criteria to represent a potential for harm, detriment or risk to the beneficial use maintenance of (highly modified) ecosystems associated with commercial and industrial use.

The area of contaminated historic fill material is close to the intersection of St Georges and Arthurton Roads and is reported to contain underground services, including fibre optic cables. It is reasonable to assume that the contaminated historic fill will remain beneath the footpath and the underground services maintained. Should removal of the footpath (and potentially the underground services) to enable landscaping / vegetation be proposed, the historical fill would need to be removed and replaced with (or covered by) an appropriate depth of soil meeting the adopted soil criteria for Maintenance of (modified) Ecosystems and Production of Food, Flora and Fibre”.

The concentrations of TPH C10-C14 (maximum concentration of 940 mg/kg) exceeds the adopted soil criteria for beneficial uses of Maintenance of Ecosystems and Production of Food, Flora and Fibre at sample locations EW23 and EW25 situated in the central portion of the site. The concentration of Total PAHs also exceeds the adopted soil criteria for beneficial uses of Maintenance of Ecosystems and Production of Food, Flora and Fibre at sample location EW25. These sample locations are located at 3.5m bgs at the base of former excavations. The Auditor does not consider the residual TPH C10-C14 and Total PAH contamination at these locations to represent a potential for harm, detriment or risk to the beneficial use Maintenance of (modified) Ecosystems and Production of Food, Flora and Fibre.

The concentrations of some metals (arsenic, barium, copper, manganese, nickel and vanadium) in the natural soil and/or imported fill material (NDCR) exceed the adopted soil criteria for beneficial uses of Maintenance of Ecosystems and Production of Food, Flora and Fibre. Given the wide spread nature of the metals in the natural soil and the relatively consistent concentrations identified across the site, the Auditor is of the opinion that the concentrations of these analytes can be attributed to background levels present in the natural soil. Similarly, the Auditor considers the elevated metals concentrations identified in the NDCR to be attributable to background concentrations of basalt NDCR sourced from the Melbourne area. The Auditor does not consider the concentrations of various metals in natural soil and imported NDCR to represent a potential for harm, detriment or risk to the beneficial use Maintenance of Ecosystems and Production of Food, Flora and Fibre.



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10.1.2 Human Health The concentrations of TPH C15-C36 (maximum concentration of 520 mg/kg), Total PAHs (maximum concentration of 73.2 mg/kg) and B(a)P (maximum concentration of 6.9 mg/kg) in historical fill beneath the footpath near the northern site boundary (see Table 3) exceed the adopted soil criteria for the beneficial use Human Health associated with low density residential use and public open space. The maximum concentration of B(a)P (6.9 mg/kg) also exceeds the adopted soil criteria for Human health associated with high density residential and commercial / industrial use. In the Auditor’s opinion, the concentrations of these compounds in historical fill (at depths ranging from 0.3m bgs to 1.5m bgs) represent a potential for harm, detriment or risk to the beneficial use Human Health associated with low density residential, public open space, high density residential and commercial / industrial use. As discussed in Section 10.1.1, it is reasonable to assume that the contaminated historic fill will remain beneath the footpath and the existing underground services maintained. Should removal of the footpath (and potentially the underground services) to enable direct access to future occupants, the historic fill would need to be removed and replaced with soil meeting the adopted soil quality criteria for human health.

The concentrations of TPH C6-C9 (maximum concentration of 110 mg/kg), TPH C10-C14 (maximum concentration of 940 mg/kg), ethylbenzene (maximum concentration of 21 mg/kg) and B(a)P (maximum concentration of 1.99 mg/kg) at between one and three sample locations in natural soil exceed the adopted soil criteria for the beneficial use Human Health associated with various land uses including low density residential, public open space, high density residential and commercial / industrial use (TPH C10-C14 only). The sample locations are located within the central portion of the site (EW23, EW25 and TA-B2 (6/6)) at a depth of 3.5 m bgs. The Auditor considers it unlikely that future site occupants would come into contact with the soil at this depth via standard soil exposure (eg. gardens, accessible soil). A depth of up to 3m is sometimes considered accessible for the construction of an in-ground swimming pool in a low density residential setting. Further, it is considered unlikely that these measured concentrations would pose an unacceptable level of risk to future users of the site (including site residents) via a pathway of vapour intrusion into buildings.

As a result, the Auditor does not consider the concentrations of residual hydrocarbon compounds and B(a)P reported to represent a potential for harm, detriment or risk to the beneficial use of Human Health associated with potential uses of the site.

The Auditor also notes that TPH concentrations remaining in the central portion of the site were assessed by the consultant at the time (2003) using different criteria (NSW EPA Service Station Guidelines) which were considered to be “industry practice” at the time (before the commencement of this Audit).

The concentration of TPH C15-C36 (465 mg/kg) at sample location EXC-WW2 at 2.0 m bgs remains in the central portion of the site. This concentration exceeds the adopted soil criteria for Human Health associated with low density residential use (300 mg/kg). In the Auditor’s opinion, the concentration of TPH at this location does not represent a potential for harm, detriment or risk to the beneficial use Human Health associated with low density residential use (including gardens / accessible soil) as the contamination is localised (single location at site) and is considered to be non volatile (i.e. unlikely to pose a vapour risk to human health). It is unlikely that contact would be made with the soil through standard soil exposure, however, exposure could occur during excavation (eg. construction of building or in-ground swimming pool).



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The concentration of total chromium (110 mg/kg) in one sample of imported NDCR fill material exceeded the adopted criteria for the beneficial use Human Health - Low Density Residential (100 mg/kg). The Auditor notes that the adopted criteria for chromium relates to hexavalent chromium (CrVI). As the imported NDCR is natural material (i.e. sourced from a quarry) and there are very few natural sources of CrVI, the chromium reported in the NDCR is most likely to be trivalent chromium (CrIII), for which the corresponding criterion is 120,000mg/kg.

The concentration of cobalt (228 mg/kg) in one sample of imported NDCR exceeds the adopted soil criteria for Human Health – Low Density Residential (100 mg/kg) and Public Open Space (200 mg/kg). Based on the statistical analysis of the total chromium and cobalt results, undertaken in accordance with the NEPM Schedule B(7A), the following was concluded:

• The average concentrations of chromium (49 mg/kg) and cobalt (22 mg/kg) in the NDCR were below the adopted NEPM HILs for both metals;

• The sample concentrations that are greater than the adopted criteria are within 2.5 times the adopted guideline values; and

• The standard deviations of chromium (16 mg/kg) and cobalt (31 mg/kg) are less than half of the adopted guideline values.

The Auditor also considers these concentrations within the imported quarried material to be naturally occurring background concentrations of basalt NDCR sourced from the Melbourne area. In the Auditor’s opinion, these concentrations of chromium and cobalt do not represent a potential for harm, detriment or risk to the beneficial use of Human Health associated with low density residential use (with gardens / accessible soil) and public open space.

10.1.3 Buildings and Structures The soil pH measured in the imported fill (NDCR) and natural soils ranged from 7.3 (SB6-1.0) to 10.1 (SB8-1.0) which is within the adopted soil criteria for the beneficial use Buildings and Structures (pH >6.5). With regards to Australian Standard 2159-2009 “Piling-Design and Installation” (AS2159), the soils are considered to be low permeability soils. For low permeability soils, at a pH of 5.5 and above the exposure classification for concrete piles in soil is considered as non-aggressive and the exposure classification for steel piles in soil is considered as non-aggressive.

Soil sulphate (as SO4) concentrations ranged from <50 to 1880 mg/kg. With regards to AS2159, the exposure classification for concrete piles in soil is considered as non-aggressive.

The Auditor notes that these results alone cannot definitively assess the potential for the soils beneath the site to be corrosive to structures, however, the beneficial use of Buildings and Structures is unlikely to be affected by the concentrations of residual hydrocarbons and metals identified at the site, which are not known to be corrosive or damaging to concrete slabs, buildings, foundations or footings.

10.1.4 Soil Aesthetics The majority of historical fill material (the exception being beneath the footpath along the northern and eastern site boundaries) was removed from the site and excavations were backfilled with 40 mm NDCR with a few exceptions. A small area within the vicinity of sample TB-NW3 in Trench B, close to the northern site boundary, was backfilled with imported clay; Trench B along the St Georges Road site boundary was backfilled with 3% stabilising slurry sand; and the north east UST 9 – 11 excavation was backfilled with ‘Liquidfill’ (ie. cement slurry). The Auditor does not consider these materials to compromise the aesthetic condition of the site or be offensive to the senses of human beings associated with the proposed residential use of the site.



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Residual historical fill material remains beneath the footpath in the north and east of the site and was reported by the site assessor to be visually affected (i.e. stained). The Auditor considers the historic fill to be aesthetically unacceptable for low density residential, public open space and high density residential use where soil is exposed. The affected fill is not expected to be aesthetically unacceptable for less sensitive uses, including commercial or industrial where less access to soil can reasonably be expected.

Staining of natural soil was also reported to have been observed in validation samples collected at the base of the three USTs removed from the northeast corner of the site. The stained natural soil was located at about 2.4m bgs underneath the fence line / edge of the footpath (see Figure 9). Due to the close proximity of these locations to underground services and St Georges and Arthurton Roads, the stained soil was not excavated, but was covered by “liquidfill” (i.e. cement slurry). It is reasonable to expect that these soils would have a hydrocarbon odour if exposed. As discussed in Section 10.1.2, contact with these soils by future site occupants is unlikely via standard soil exposure (eg. gardens, accessible soil) and is even more unlikely due to the presence of the overlying liquidfill.

Residual hydrocarbons are present in natural soils at depths of 2m bgs (one sample) and 3.5m bgs (three samples). As discussed in Section 10.1.2, contact with these soils by future site occupants is unlikely via standard soil exposure (eg. gardens, accessible soil). Exposure to these soils could occur during construction or excavation (eg. in-ground swimming pool). Soils at these locations may have a hydrocarbon odour which is likely to be aesthetically unacceptable for standard residential use. A slight hydrocarbon odour was noted by Coffey field staff during drilling of monitoring well, MW7, at 5.0 m bgs within the natural siltstone.

In the Auditors opinion, the potential for exposure to natural soil that is stained or containing residual hydrocarbon odour does not represent a potential for harm, detriment or risk to the beneficial use Aesthetics associated with the potential residential use of the site on the basis that exposure of future occupants to the aesthetically impacted soil is unlikely and that it does not represent a risk to human health or the environment.

10.2 Groundwater The beneficial uses of groundwater to be protected at the site are identified in Section 6.3. The current condition of groundwater at the site is described in Section 9.3. No remediation of groundwater has occurred at the site.

An assessment of the harm, detriment or risk to beneficial uses of groundwater posed by the groundwater quality of the site is provided below.

10.2.1 Maintenance of Ecosystems The concentrations of dissolved metals (cadmium, copper, nickel and/or zinc) in excess of the adopted GWQOs for the beneficial use Maintenance of Ecosystems has been reported at various well locations on and off the site. After considering the primary data and Auditor verification sample, the Auditor considers that the concentrations of these metals represent background conditions with respect to site activities. Metals concentrations in the off-site, down hydraulic gradient wells (MW3 and MW4) and on-site monitoring wells were similar to those detected in the off-site up hydraulic gradient wells (MW1 and MW2), suggesting the concentrations of metals are wide spread and not attributable to on-site activities. In accordance with the SEPP (GoV), where naturally occurring background concentrations exceed the nominated GWQOs, the background concentrations become the objectives.



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This beneficial use applies at the point of discharge to surface water (i.e. not at the site). The closest surface water receptor is Merri Creek, located 550 m south-west of the site.

In the Auditor’s opinion, the reported concentrations of metals represent background concentrations and do not represent a potential for harm, detriment or risk to the beneficial use Maintenance of Ecosystems.

10.2.2 Agriculture, Parks and Gardens Concentrations of MTBE in groundwater from monitoring wells MW5, MW8, MW9, MW10 and MW17 exceeds the adopted GWQO (20 ug/L) for the beneficial use Agriculture, Parks and Gardens. This GWQO is based on aesthetic impacts (taste and odour) in drinking water rather than health impacts and has been conservatively applied to the beneficial use Agriculture, Parks and Gardens (odour observed if using impacted groundwater to spray garden from a hand held hose). The Auditor notes that other methods of application of groundwater to irrigate gardens may not result in an unpleasant odour and would not affect this beneficial use.

In the most recent rounds of groundwater monitoring in February and July 2010, concentrations of MTBE exceeding the adopted GWQO (20ug/L) ranged from 33 ug/L (MW10 in July 2010) to 202 ug/L (MW5 in July 2010). The Auditor notes that MW6, which reported a concentration below the adopted GWQO of 12 ug/L in November 2009, was decommissioned in February 2010 to enable the removal of USTs 9 to 11 in the north east corner of the site.

Coffey undertook an assessment of whether natural attenuation of MTBE at the site was likely to be occurring by assessing primary and secondary lines of evidence (refer to Sections 5.1 and 5.2 of Coffey, 2010e, for a detailed discussion). The Auditor concurs with Coffey’s conclusions that the primary and secondary lines of evidence are inconclusive and that natural attenuation through biodegradation is limited.

Fate and transport modelling (BIOSCREEN-AT Version 1.42) was also undertaken by Coffey to estimate the potential for MTBE to migrate off-site and predict the likely extent of dissolved phase MTBE, using the November 2009 and February 2010 groundwater analytical results using. The modelling estimated that MTBE concentrations greater than the GWQO (20 ug/L) may migrate up to approximately 28 m from MW5, the assumed on-site source, and therefore extend partially under two residential properties immediately west of the site, however, the concentration of MTBE would be within the range recommended by the USEPA (upper limit of 40 ug/L).

As a result, the Auditor considers that beneficial use Agriculture Parks and Gardens is precluded by the concentrations of MTBE in some wells at the site and potentially in groundwater located a short distance down gradient of the site.

The concentration of nickel exceeded the beneficial use Agriculture, Parks and Gardens at monitoring well MW11 (0.356 mg/L) in September 2008 (the last time metals were analysed). After considering the primary data and Auditor verification sample, the Auditor considers that the concentrations of nickel represent background conditions with respect to site activities (see Section 10.2.1), and do not represent harm, detriment or risk to the beneficial use Agriculture, Parks and Gardens.



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10.2.3 Stockwatering The concentration of benzene identified at MW7 (4 ug/L in September 2008 and 3 ug/L in November 2009) exceeded the GWQO for the beneficial use Stockwatering. However, the benzene concentration at MW7 in the latest round of monitoring in February 2010 was below the laboratory LOR and GWQO (1 ug/L). In the Auditors opinion, the concentration of benzene in groundwater does not represent potential harm, detriment or risk to the beneficial use Stockwatering.

The concentrations of sulphate in groundwater from monitoring wells MW7, MW11 and MW17 consistently exceed the GWQO for Stockwatering (1,000 mg/L). Sulphate concentrations have been historically high in monitoring wells MW7 (9,020 mg/L in February 2010) and MW11 (6,830 mg/L in February 2010) and exceed the laboratory measured TDS concentrations for these wells (6,120 mg/L and 5,550 mg/L respectively). Re-analysis by the laboratory confirmed the original sulphate results and laboratory personnel suggested that there is possibly another source of sulphate in these samples that is not incorporated into the TDS determination. In the Auditor’s opinion, the sulphate results are anomalous and the site is not the source of the elevated sulphate concentrations, however, he has conservatively adopted the results. Therefore, the beneficial use Stockwatering is potentially limited (rather than precluded) by the concentrations of sulphate in some wells at the site. The Auditor also notes that this beneficial use is neither existing nor likely to be realised at or in the vicinity of the site as it is inconsistent with the existing and likely future land use at or in the vicinity of the site.

10.2.4 Industrial Water Use The measured pH levels are outside the adopted GWQO range of 6.0 to 8.3 pH units for industrial use for once through cooling systems (brackish classification) at monitoring well locations MW11 (pH 5.9) and MW16 (pH 5.7). Sulphate concentrations exceed the adopted GWQO (2,700 mg/L) at monitoring well locations MW7 (9,020 mg/L) and MW11 (6,830 mg/L). Issues associated with reported sulphate concentrations are discussed in Section 10.2.3. In the Auditors opinion, the concentrations of these parameters potentially limit (rather than preclude) this beneficial use. The Auditor also notes that this beneficial use is neither existing nor likely to be realised at or in the vicinity of the site as it is inconsistent with the existing and likely future land use at or in the vicinity of the site.

10.2.5 Primary Contact Recreation The concentrations of MTBE in groundwater from monitoring wells MW5, MW8, MW9, MW10 and MW17 exceed the adopted GWQO (20 ug/L) for the beneficial use Primary Contact Recreation. The GWQO is based on aesthetic impacts (taste and odour) in drinking water rather than health impacts and has been conservatively applied to the beneficial use Primary Contact Recreation (odour and/or taint during incidental ingestion in pools/spas filled with groundwater).

In the most recent groundwater monitoring (February and July 2010), concentrations of MTBE exceeding the GWQO ranged from 33 ug/L (MW10 in July 2010) to 202 ug/L (MW5 in July 2010).

Section 10.2.2 discusses the natural attenuation and fate and transport modelling undertaken by Coffey. The modelling estimated that MTBE concentrations greater than the GWQO (20 ug/L) may migrate up to approximately 28 m from MW5, the assumed on-site source, and therefore extend partially under two residential properties situated immediately west of the site, however, the concentration of MTBE would be within the concentration range recommended by the USEPA (20ug/L to 40 ug/L).



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As a result, the Auditor considers that beneficial use primary contact recreation is precluded by the concentrations of MTBE in some wells at the site and potentially in groundwater located a short distance down gradient of the site. The Auditor also notes that this beneficial use is neither existing nor likely to be realised at or in the vicinity of the site.

Concentrations of nickel (single sample from MW11) and sulphate in groundwater at the site exceed the adopted GWQOs for the beneficial use Primary Contact Recreation. As described in Section 10.2.1 above, the concentrations of nickel are considered to represent background conditions at the site. As discussed in Section 10.2.3 above, it is the Auditor’s opinion that the sulphate results are anomalous and the site is not the source of the elevated sulphate concentrations. However, he has conservatively adopted the results and therefore, the beneficial use Primary Contact Recreation is potentially limited (not precluded) by the concentrations of sulphate in some wells at the site. This beneficial use is neither existing nor likely to be realised at or in the vicinity of the site.

The concentration of chloride (4,460 mg/L at MW1 in September 2008) exceeded the adopted GWQO for the beneficial use Primary Contact Recreation. MW1 is located off-site (upgradient). The Auditor did not consider the chloride concentration in groundwater from MW1 to represent harm, detriment or risk to the beneficial use Primary Contact Recreation.

10.2.6 Buildings and Structures Field measurements of groundwater pH recorded by Coffey during groundwater sampling ranged from 5.7 (MW16 in February 2010) to 8.0 (MW5 in July 2010), classifying the groundwater as “non-aggressive” to concrete and steel structures in accordance with AS2159-2009 - Table 6.4.2. Historical chloride concentrations (September 2008) within the groundwater range from 20 to 4,660 mg/L, classifying the groundwater as ‘non-aggressive” according to AS2159-2009 - Table 6.4.2. Sulphate concentrations ranged from 16 to 5,696 mg/L, classifying the exposure as “moderate” to concrete and steel structures in accordance with AS2159 – Table 6.4.2. This primarily relates to the potential for sulphate attack of buried concrete and unprotected steel. Overall, due to the concentrations of sulphate in groundwater, the exposure classification for steel and concrete structures in contact with groundwater is “moderate”.

There is a likelihood that building foundations will be deep enough to come into contact with groundwater (> 2.5 mbgs). AS 2159-2009 indicates that for a site classified as “moderate” where sulphate levels exceed 2,000 mg/L, reference should be made to AS 3735-2001 “Concrete structures for Retaining Liquids” and Supplement (AS3735 – Supplement 1 – 2001) for advice on concrete design.

10.3 Groundwater (CUTEP) No direct groundwater remediation has been undertaken or is proposed for this site.

As outlined in EPA Publication 840, polluted groundwater should be cleaned up such that beneficial uses (existing and potential) are restored. Where the restoration of beneficial uses is not possible or feasible, polluted groundwater must be cleaned up to the extent practicable.

An assessment of the practicability of various remedial techniques for the clean up of the MTBE contamination is included in Section 7 of the Coffey CUTEP report (2010e) (Appendix H). The review considers technical, logistical and financial aspects of identified remedial techniques as well as on-going management and timing (ie. reasonable timeframe) considerations.



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The Auditor reviewed the Coffey CUTEP report and concurred with Coffey’s conclusion that clean up of groundwater (in addition to primary and secondary source removal that has occurred at the site) is not practicable as it is not commensurate with the environmental significance of the environmental issues being addressed.

The rationale for this conclusion is as follows:

• There has been extensive groundwater investigation at the site with each well being monitored between three and six times since 2008;

• There is no evidence of NAPL on or off-site;

• Groundwater flow velocity is estimated to be in the vicinity of 3 m/year (based on slug test data conducted on wells MW5 and MW15 during November 2008) and the plume is considered to be relatively stable;

• Groundwater occurs within a tight siltstone aquifer system which means that the application of further remedial technologies is not likely to restore groundwater beneficial uses;

• All primary sources of contamination have been removed and extensive excavation of secondary sources (contaminated fill and natural soil) have been removed form the site;

• Concentrations of contaminants are relatively low (maximum MTBE concentration of 202 ug/L in July 2010) and appear to be either relatively stable or decreasing;

• A human health risk assessment has demonstrated that impact detected in groundwater is considered unlikely to pose an unacceptable health risk to future on and off-site residential occupants or maintenance and construction workers;

• The extent of the polluted groundwater is limited to the north and west of the site and potentially off-site;

• Groundwater fate and transport modelling indicates that MTBE concentrations greater than the GWQO (20 ug/L) may migrate up to approximately 28 m from MW5, the assumed on-site source, and therefore partially under two residential properties immediately west of the site, however, they would be within the concentration range recommended by the USEPA (20ug/L to 40 ug/L) (refer to Appendix A1 of Coffey, 2010e);

• The adopted GWQO for the beneficial use Agriculture, Parks and Gardens and Primary Contact Recreation relates to an aesthetic impact (odour, taste) in drinking water and therefore is conservatively applied in this context;

• The use of groundwater for these purposes in the future is unlikely due to the cost of installing a groundwater production bore (estimated to be in the vicinity of $5 - $15K), the relatively low yield of the Silurian siltstone aquifer, the background TDS of the groundwater (up to 6,500 mg/L) and the presence of reticulated water; and

• The nearest registered groundwater bore (for investigative purposes) to the site is in excess of 600 m to the southeast of the site and south of Merri Creek and is located in a different aquifer.

The Auditor does not consider ongoing monitoring of MTBE in groundwater at the site to be necessary due to the:

• Limited spatial extent of groundwater containing MTBE concentrations greater than the adopted GWQO (determined by both direct measurement and estimated groundwater modelling);

• Relatively consistent concentrations of MTBE measured in wells at the site;



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• The adopted GWQO being based on potential aesthetic impacts (odour, taste) rather than potential toxicity related impacts on protected beneficial uses; and

• The low likelihood of protected beneficial uses of groundwater being realised at and in the vicinity of the site.

Ongoing management of polluted groundwater at the site is proposed to comprise controls on the use of polluted groundwater, including the provision of information to ensure that affected landholders or subsequent landholders are aware of the polluted groundwater and beneficial uses that are precluded.

It is proposed that the information provision be in the form of:

• The Statement of Environmental Audit for the site should contain a condition stating that groundwater at the site is polluted and is not suitable for the beneficial uses Agriculture, Parks and Gardens and Primary Contact Recreation (and should not be abstracted and used for these purposes). The Statement is required to be provided to any person who proposes to become the occupier (s53ZE of the Environment Protection Act, 1970); and

• Identification of a Groundwater Quality Restricted Use Zone (GQRUZ) consistent with EPA Publications 759.1 and 840 where it has determined that CUTEP has occurred. In accordance with current advice from EPA, notification of a GQRUZ is required to those parties potentially affected by a GQRUZ. This would include all persons intending to occupy or purchase the site and residential properties to the west of the site.

The proposed extent of a GQRUZ that is recommended to be identified for this site is the site itself, and the adjoining two properties to the immediate west of the site (see Figure 10).

Based on the above, the Auditor submitted an opinion on Clean up (of Polluted Groundwater) to the Extent Practicable (CUTEP) at the site to EPA on 7 September 2010 and subsequent information on 4 and 7 October 2010 and 22 November 2010. EPA provided a determination on CUTEP on 14 December 2010. The CUTEP submission and determination is attached as Appendix H.

In its determination of CUTEP for the site, EPA:

• Determined that groundwater has been cleaned up to the extent practicable;

• Identified the site as within a Groundwater Quality Restricted Use Zone (GQRUZ) (including the two neighbouring properties on the western site boundary); and

• Instructed the Auditor to ensure that the Statement of Environmental Audit for the site includes:

— A condition restricting groundwater use for existing and potential precluded extractive beneficial uses of groundwater; and

— Other related information - stating that EPA has determined CUTEP and that the site is within a GQRUZ; a list of beneficial uses for which groundwater is suitable; noting that EPA may require periodic reassessment of the practicability of clean up.


94 43512483/R001/A

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11 Auditor's Conclusions

11.1 Findings of the Audit The site has historically been used as a petroleum service station with an associated workshop. Infrastructure at the site included eleven USTs, bowsers, fill points and associated fuel lines, sales building and workshop including triple interceptor trap and hydraulic hoist. The site was closed in about 1998 and decommissioned in 2003, and has undergone environmental assessment and remediation between 1998 and 2010.

All infrastructure relating to the former use has been removed. Remediation of the site comprised excavation and removal of contaminated soil. Soil covering virtually the entire site has been excavated to depths between 1.8 and 5.0m below ground surface. Soil remaining on site has been validated. Excavations were backfilled with imported fill material (mainly NDCR from commercial quarries).

The site owner (Mobil) proposes to divest the site for use consistent with its land use zone (ie. residential – R1Z). The proposed use of the site is unknown, however it is assumed to be residential.

After considering the environmental condition and beneficial uses of the site, the Auditor has assessed any harm, detriment or risk to those beneficial uses and concluded the following:

• The Auditor is not aware of any imminent environmental hazards that are associated with the site;

• Historical fill material, which could not be excavated due to its proximity to St Georges and Arthurton Roads and the presence of underground services, remains beneath the footpath in the northeast of the site. The historic fill contains concentrations of TPH C15-C36, B(a)P, Total PAH and zinc that exceed the adopted soil criteria for beneficial uses associated with low density residential use, public open space, high density residential use and commercial industrial use. The Auditor considers that the historic fill beneath the footpath in the northeast of the site represents a potential for harm, detriment or risk to those beneficial uses. The historical fill is also considered to be aesthetically unacceptable for low density residential use, high density residential use and public open space with accessible soils;

• Residual concentrations of TPH, ethylbenzene, Total PAH and B(a)P in a small number of samples of natural soil at depths of 2m bgs and 3.5m bgs exceed the adopted soil criteria for beneficial uses associated with low and high density residential use, public open space and commercial / industrial use. It is reasonable to expect that these soils would have a hydrocarbon odour if exposed. Staining of natural soil was also reported to have been observed in validation samples collected at the base of the three USTs removed from the northeast corner of the site. The stained natural soil was located at about 2.4m bgs underneath the fence line / edge of the footpath The stained soil was not excavated, but was covered by “liquidfill” (i.e. cement slurry). Due to the depth of the stained and potentially odorous soils, it is unlikely that future site occupiers would come into contact with these soils via standard soil exposure (gardens / accessible soil). Further, it is considered unlikely that these measured concentrations would pose an unacceptable level of risk to future users of the site (including residents) via a pathway into buildings. The Auditor does not consider the concentrations of these compounds at the stated locations to represent a potential for harm, detriment or risk to beneficial uses of the site. If exposed during future construction or excavation (eg. in-ground swimming pool), soils at these locations may have a hydrocarbon odour;



43512483/R001/A 95

• Natural soil and imported backfill (NDCR) at the site contains concentrations of metals (arsenic, barium, chromium, cobalt, copper, manganese, nickel and vanadium) above the adopted soil criteria for various beneficial uses. The Auditor considers these metals to be representative of background concentrations and not to represent a potential for harm, detriment or risk to beneficial uses of the site;

• The concentrations of dissolved metals (cadmium, copper, nickel and zinc) in groundwater exceed the GWQOs for the beneficial use maintenance of ecosystems (as well as agriculture, parks and gardens and primary contact recreation in the case of nickel in a single sample). The concentrations of these metals represent background conditions which are not considered to adversely affect the benefical uses of groundwater;

• Concentrations of MTBE in groundwater in some wells on-site and potentially in groundwater located a short distance off-site are considered to preclude the beneficial uses Agriculture, Parks and Gardens and Primary Contact Recreation. These beneficial uses are neither existing nor likely at or in the vicinity of the site; and

• The concentrations of sulphate in groundwater in two wells (MW7 and MW11) at the site exceed the GWQOs for the beneficial uses stock watering, primary contact recreation, industrial water use and buildings and structures. The concentration of sulphate in groundwater from MW17 exceeds the GWQO for stockwatering. These concentrations of sulphate are considered to be anomalous and not related to activities at the site. As a result, these beneficial uses are considered to be limited (not precluded) by the reported sulphate concentrations;

• Based on the CUTEP submission by the Auditor to EPA, EPA determined that the Clean up (of polluted groundwater) to the extent practicable had occurred.

Due to the presence of contaminated (TPH C15-C36, B(a)P, Total PAHs and Zinc) and aesthetically impacted historical fill material located beneath the footpath in the northeast of the site, as well as the contamination of groundwater by MTBE resulting from site activities that precludes the beneficial uses Agriculture, Parks and Gardens and Primary Contact Recreation, the site is not considered to be suitable for all beneficial uses.

The Site is considered suitable for the beneficial uses associated with low density residential use, public open space, high density residential use and commercial/industrial use, subject to the following:

• The concrete footpath (or similar physical barrier) covering the historical fill adjacent to St Georges and Arthurton Roads in the northeast of the site must be maintained. If the barrier is damaged or removed during site works, it must be reinstated as soon as possible to the same condition or better than prior to the disturbance.

• Should removal of the footpath covering the historical fill be proposed to enable landscaping / vegetation or direct soil access by future occupants, the historic fill material must be removed and replaced with soil that is suitable for the proposed use.

• Should removal of the footpath covering the historical fill be proposed to enable installation or maintenance of underground services, the historic fill material must be reinstated beneath the barrier or removed from the site in accordance with EPA requirements for the disposal or re-use of contaminated soil.

• Groundwater at the site is polluted and must not be used for Agriculture, Parks and Gardens and Primary Contact Recreation.



96 43512483/R001/A

The reason for refusing to issue a Certificate of Environmental Audit for the site is the presence of contaminated and aesthetically impacted historical fill material in the northeast of the site (that is not suitable for all beneficial uses) as well as the groundwater contamination (MTBE) resulting from site activities that precludes some beneficial uses.

In addition to the above, future occupiers of the site should note the following:

• The groundwater bores at (and relating to) the site should be decommissioned in accordance with the Minimum Construction Requirements for Water Bores in Australia (Edition 2, September 2003), to ensure that they do not act as a conduit for groundwater contamination in future;

• Residual concentrations of TPH and staining are located in natural soil at depths of greater than 2m. Although these are not considered to represent a health or ecological risk, this soil may have a hydrocarbon odour or be otherwise aesthetically impacted if it is exposed during construction or excavation;

• The following beneficial uses of groundwater are not precluded by the polluted groundwater : maintenance of ecosystems, stockwatering, industrial water use and buildings and structures;

• The concentrations of sulphate in groundwater at parts of the site may limit the ability for groundwater to be used for stockwatering, industrial water use and buildings and structures;

• Where building foundations are likely to come into contact with groundwater at the site (i.e. at depths greater than 2.5m bgs) AS 2159-2009 indicates that for a site classified as “moderate” where sulphate levels exceed 2,000 mg/L, reference should be made to AS 3735-2001 “Concrete structures for Retaining Liquids” and Supplement (AS3735 – Supplement 1 – 2001) for advice on concrete design;

• The Environment Protection Authority (EPA) has determined that: - groundwater has been cleaned up to the extent practicable; and - the site is within a Groundwater Quality Restricted Use Zone (GQRUZ);

• The extent of the GQRUZ identified by EPA comprises the site itself and the adjoining two residential properties to the immediate west of the site;

• On-going monitoring of groundwater quality at and around the site is not required; and

• In accordance with clause 19(3) of the State Environment Protection Policy (Groundwaters of Victoria), the Authority may require periodic reassessment of the practicability of groundwater clean up.

11.2 Issue of Statement of Environmental Audit After considering the issues described in this Audit Report, and in accordance with Part IXD of the Environmental Protection Act 1970, the Environmental Auditor has decided to issue a Statement of Environmental Audit. The Environmental Auditor makes the Statement as included at the front of this report. The Statement of Environmental Audit confirms that the environmental condition of the site is suitable for low and high density residential use, public open space and commercial/ industrial uses provided the stated conditions are met.


98 43512483/R001/A

12

12 References

ANZECC/NHMRC, 1992. Assessment and Management of Contaminated Sites, Australian and New Zealand Environment and Conservation Council and National Health and Medical Research Council, January 1992.

ANZECC, 1992. Australian Water Quality Guidelines for Fresh and Marine Waters, Australian and New Zealand Environment and Conservation Council, November 1992.

ANZECC, 1996. Guidelines for the Laboratory Analysis of Contaminated Soils, Australian and New Zealand Environment and Conservation Council, August 1996.

Birch W. D. (Editor), 2003. Geology of Victoria Geological Society of Australia (Victoria Division), Special Publication 23.

Budavari, S. ed, 1989. The Merck Index- An Encyclopaedia of Chemicals, Drugs and Biologicals 11th Edition. Merick & Co., Inc. USA.

CCME, 2001a. Canadian Council of Ministers of the Environment, Canada-Wide Standards for Petroleum Hydrocarbons in Soil, 2001.

CCME, 2001b, Canadian Council of Ministers of the Environment, Canada-Wide Standards for Petroleum Hydrocarbons in Soil, Technical Supplement, 2001.

Coffey Environments Pty Ltd, 2006. Phase 1 Environmental Site Assessment Report, Mobil Service Station Northcote (VO1003), Corner St. Georges and Arthurton St, Northcote, Victoria, 25 July 2006.

Coffey Environments Pty Ltd, 2007. Further Tank Excavation Assessment Report, Former Mobil Service Station, Corner St. Georges and Arthurton Road, Northcote, Victoria, 9 January 2007.

Coffey Environments Pty Ltd, 2008a. Phase 2 Environmental Site Assessment Report, Former Mobil Northcote Service Station (VO1003), Corner St Georges and Arthurton Road, Northcote, Victoria, 11 July 2008.

Coffey Environments Pty Ltd, 2008b. Soil Validation Assessment, Mobil Northcote Service Station (VO1003), Corner of St. Georges and Arthurton Roads, Northcote VIC 3070, 17 December 2008.

Coffey Environments Pty Ltd, 2008c. Post Phase 2 Environmental Site Assessment, Former Mobil Northcote Service Station (VO1003), Corner St Georges and Arthurton Road, Northcote, VIC 3070, 19 December 2008.

Coffey Environments Pty Ltd, 2009a. Annual Groundwater Monitoring Event, Former Mobil Northcote Service Station (VO1003), Corner St Georges and Arthurton Road, Northcote, VIC 3070, 3 February 2009.

Coffey Environments Pty Ltd, 2009b. Groundwater Fate and Transport Modelling – Former Mobil Service Station Northcote (VO1003), 137-151 St Georges Road, Northcote, VIC 3070, 9 July 2009.

Coffey Environments Pty Ltd, 2009c. Post Phase 2 Environmental Site Assessment, Former Mobil Northcote Service Station (VO1003), Corner of St Georges Road and Arthurton Road, Northcote, Victoria, 10 July 2009.

Coffey Environments Pty Ltd, 2010a. Groundwater Monitoring Event, Former Mobil Northcote Service Station (VO1003), Corner of St Georges Road and Arthurton Road, Northcote, Victoria, 18 February 2010.


12 References

43512483/R001/A 99

Coffey Environments Pty Ltd, 2010b. Health Risk Assessment, Former Mobil Northcote Service Station (VO1003), 137-151 St Georges Road, Northcote, Victoria 3070, 30 April 2010.

Coffey Environments Pty Ltd, 2010c. Further Tank Excavation Assessment Report, Former Mobil Northcote Service Station (VO1003), 137-151 St Georges Road, Northcote, Victoria, 29 April 2010.

Coffey Environments Pty Ltd, 2010d. Interim Groundwater Monitoring Event, Former Mobil Northcote Service Station (VO1003), Corner of St Georges Road and Arthurton Road, Northcote, Victoria, 19 August 2010.

EnviroProtect Pty Ltd, 2006. Inspection and Evaluation of Hazardous Materials, Part 6 Asbestos & Hazardous Materials, at 137-151 St. Georges Road, Northcote (VO1003), December 2006.

EPAV, Publication 448.1, Information Bulletin, Classification of Wastes, Environment Protection Authority, May 2004.

EPAV, Publication 448.3, Information Bulletin, EPA Publication 448 Classification of Wastes, Environment Protection Authority, May 2007.

EPAV, Publication 1178, Information Bulletin, Soils Sampling Guideline (Off-Site Management and Acceptance to Landfill), Environment Protection Authority, November 2007.

Handex Australia Pty Ltd, 2002. Environmental Site Assessment – Closed Service Station Facility, Cnr St Georges Road and Arthurton Street, Northcote, Victoria, site No. VO1003, 4 January 2002.

IT Environmental (Australia) Pty Ltd, 2006. Tank Excavation Assessment Report, Former Mobil Service Station, Corner of St. Georges and Arthurton Street, Northcote, Victoria, 23 October 2006.

National Industrial Chemicals Notification and Assessment Scheme (NICNAS), 2001. Benzene, Priority Existing Chemical Assessment Report No. 21. Commonwealth of Australia, September 2001.

NEPC, 1999. National Environment Assessment of Site Contamination Measure, National Environmental Protection Council, December 1999.

NHMRC, 2004, Australian Drinking Water Guidelines, National Health and Medical Research Council in collaboration with the Natural Resource Management Ministerial Council, 2004.

SEPP (Groundwaters of Victoria), 1997, State Environment Protection Policy (Groundwaters of Victoria), Victorian Government Gazette No. S160, December 1997.

SEPP (Waters of Victoria), 2003, Variation to State Environment Protection Policy (Waters of Victoria), Victorian Government Gazette No. S107, June 2003.

SEPP (Land), 2002, State Environment Protection Policy (Prevention and Management of Contamination of Land, Victorian Government Gazette No. S95, June 2002.

Shineldecker, 1992. Handbook of Environmental Contaminants: A Guide for Site Assessment, Lewis Publishers, USA.

Standards Australia, Australian Standard 4482.2, Guide to the Sampling and Investigation of Potentially Contaminated Soil – Volatile Substances, 1999.

Standards Australia, Australian Standard 4482.1, Guide to the Investigation and Sampling of Sites with Potentially Contaminated Soil – Non-volatile and Semi-volatile Compounds, 2005.

Standards Australia, Australian Standard 2159-1995, Piling – Design and installation, 5 August 1995.


12 References

100 43512483/R001/A

URS Australia Pty Ltd, 2010. Submission on Clean Up to the Extent Practicable (CUTEP) – Former Northcote Service Station – EPA Ref: 48726. 7 September 2010.

USEPA, Region 9 Preliminary Remediation Goals, United States Environmental Protection Agency, 1996.

Wright J. and Howell M., 2003. Volatile Air Emissions from Soil or Groundwater – Are They as Significant as Models Say They Are? In Contaminated Soils, Volume 8, Edited by Edward J. Calabrese, Paul T. Kostecki and James Dragun, p375-393.

VROM, 2000. Ministerial Circular on Target and Intervention Values for soil remediation. The Hague, The Netherlands: Ministry of Housing, Spatial Planning and the Environment (VROM).


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13

13 Limitations

This Audit report and Statement of Environmental Audit have been prepared in accordance with Section 53X of the Environment Protection Act 1970. The Statement of Environmental Audit represents the Auditor’s opinion of the environmental condition of the site and its suitability for beneficial uses at the date the Statement is signed.

It is acknowledged that the Audit report may be used by Mobil Oil Australia Pty Ltd, by the Environment Protection Authority and by the relevant planning authority (i.e. Darebin City Council) in reaching conclusions about the site. The scope of work performed in connection with the Audit may not be appropriate to satisfy the needs of any other person. Any other person’s use of, or reliance on, the Audit document and report, or the findings, conclusions, recommendations or any other material presented to them, is at that person’s sole risk.

In forming an opinion, the Auditor has relied on information supplied by Coffey Environments Pty Ltd. The Auditor has taken this information to represent a fair and reasonable characterisation of the site, within the limitations of the investigation as stated herein. No investigation, in practice, can be thorough enough to preclude the presence of materials on the subject property that presently, or in the future, may be considered hazardous. The actual characteristics of sub-surface and surface materials may vary significantly between adjacent test points and sample intervals and at locations other than where direct observation, measurement or exploration have been made. Due to often-changing regulatory evaluation criteria, concentrations of contaminants present and considered to be acceptable may, in the future, become subject to different regulatory standards.

Opinions and judgements expressed herein, which are based on the Auditors understanding and interpretation of current regulatory standards, should not be construed as legal opinions.

In the event that changes in conditions on or near the site either exist or occur after the date of signing of a Certificate or Statement of Environmental Audit, the Auditor disclaims responsibility for the occurrence or ownership or effects of such conditions or materials, whether they are hazardous or otherwise.


43512483/R001/A

Tables (attached)

Table 1 Adopted Soil Criteria for Beneficial Uses of Land

Table 2 Adopted Groundwater Quality Objectives

Table 3 Exceedances of Adopted Soil Criteria after Remediation/Validation

Table 4 Exceedances of Adopted Groundwater Quality Objectives after Remediation/Validation

Antimony mg/kg 311 124* 62** 4101 - - -Arsenic mg/kg 100 400 200 500 20 20 -Barium mg/kg 150001 60000* 30000** 1900001 300 300 -Beryllium mg/kg 20 80 40 100 - - -Boron mg/kg 3000 12000 6000 15000 - - -Cadmium mg/kg 20 80 40 100 3 3 -Chromium mg/kg 100 400 200 500 400a 400a -Chromium (III) mg/kg 120000 480000 240000 600000 400 400Chromium (VI) mg/kg 100 400 200 500 1 1 -Cobalt mg/kg 100 400 200 500 - - -Copper mg/kg 1000 4000 2000 5000 100 100 -Lead mg/kg 300 1200 600 1500 600 600 -Manganese mg/kg 1500 6000 3000 7500 500 500 -Mercury mg/kg 15 60 30 75 1 1 -Nickel mg/kg 600 2400 600 3000 60 60 -Tin mg/kg 470001 188000* 94000** 6100001 50*** 50*** -Vanadium mg/kg 3901 1560* 780** 52001 50 50 -Zinc mg/kg 7000 28000 14000 35000 200 200 -Cyanides (complexed) mg/kg 500 2000 1000 2500 - - -Cyanides (free) mg/kg 250 1000 500 1250 - - -

Benzo(a)pyrene mg/kg 1 4 2 5 - - -Total PAH mg/kg 20 80 40 100 185 185 -Phenol mg/kg 8500 34000 17000 42500 - - -

TPH C6-9 mg/kg 302 302 60** 3202 2102 2102 -TPH C10-14 mg/kg 1502 600* 300** 2602 1502 1502 -TPH C15-36 mg/kg 3002 1200* 600** 17002 13002 13002 -TPH >C16-C35 Aromatics mg/kg 90 360 180 450 - - -TPH >C16-C35 Aliphatics mg/kg 5600 22400 11200 28000 - - -

Benzene mg/kg 1.11 1.11 2.2** 5.41 253 253 -Toluene mg/kg 50001 50001 10000** 450001 753 753 -Ethyl Benzene mg/kg 5.41 5.41 10.8** 271 553 553 -Total Xylenes mg/kg 6301 6301 1260** 27001 653 653 -

TCE mg/kg 2.81 2.81 5.6** 141 0.053 0.053 -PCE mg/kg 0.551 0.551 1.1** 2.61 - - -1,2, cis DCE mg/kg 1601 1601 320** 20001 - - -Acetone mg/kg 610001 610001 122000** 6300001 - - -Formaldehyde mg/kg 120001 120001 24000** 1200001 - - -

Aldrin + Dieldrin mg/kg 10 40 20 50 - - -Chlordane mg/kg 50 200 100 250 - - -DDT + DDD + DDE mg/kg 200 800 400 1000 - - -Heptachlor mg/kg 10 40 20 50 - - -

Total PCBs mg/kg 10 40 20 50 - - -

Sulphate mg/kg - - - - 2000 2000 2000pH pH units - - - - - - >5.54

Phosphorus mg/kg - - - - 2000 2000 -Chlorides mg/kg - - - - - - -Asbestos - - - -

1 USEPA, 2010. Regional Screening Levels2 CCME, 2008. Canada-wide standard for petroleum hydrocarbons in soil3

4 CSA, 2009. AS2159-2009. Australian Standard: Piling - design and Installation.5 USEPA, 2007. Ecological Screening Levels for Soil PAHs (Interim Final). Value for the protection of invertebrates selected.a

*

** Human Health Low Density Residential Criteria multiplied by a factor of 2 in accordance with NEPM (1999).*** ANZECC, 1992. Environmental Investigation Level.

CCME, 2007. Environmental Quality Guidelines from Canadian Soil Quality Guidelines for the Protection of Environmental and Human Health. Individual values taken from supporting technical documents for the respective chemicals.

For Maintenance of Ecosystems and Production of Food, Flora, Fibre the guideline for Chromium III has been adopted for total chromium. This guideline assumes Cr VI concentrations are negligible.Human Health Low Density Residential Criteria for non-volatile components multiplied by a factor of 4 for high-density residential in accordance with NEPM (1999).

Human Health-Commercial/

Industrial

Maintenance of Ecosystems

No visual evidence of asbestos

Table 1Adopted Soil Criteria for Beneficial Uses of Land

Analyte Units Human Health-Low Density

Buildings and Structures

Production of food, flora, fibre

Human Health-High Density

Human Health-Public Open

Space

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Table 2Adopted Groundwater Quality Objectives

Analyte Units

Maintenance of Ecosystems - 95%

Freshwater (based on Urban Waterways

Segment, modified ecosystems) (ANZECC,

2000)

Agriculture, Parks, and Gardens

(ANZECC, 2000)

Stockwatering (ANZECC 2000)

Primary Contact Recreation

(NHMRC 2008)1

Buildings and Structures (AS2159

- 2009)

Industrial Water Use (based on ANZECC 1992, once through

cooling and make-up water)

Major Anions/CationsTDS mg/L - - 2000 5000a <35,000****pH units - - - 6.5 - 8.5 >6.5 6.0-8.3****Ammonia total mg/L 0.9*** - - 5a -Ammonia as N mg/L - - - 4.1a - -Calcium mg/L - - 1000 - <420****Chloride mg/L - c - 4000h <6,000 <19,000****Cyanide Total mg/L 0.007 - - 0.8h -Fluoride mg/L - - 2 15h -Nitrate as N mg/L 7.2 - 90.3 112h -Nitrite as N mg/L 0.16 - 9.12 9h -Nitrate mg/L 31.9 - 400 500h -Nitrite mg/L - - 30 30hSulphide mg/L - - - 0.05¤ -Sulphate (as SO4) mg/L - - 1000 2500a <1,000 <2,700****Sulphate as S mg/L - - 333.3 833.3a -Sodium mg/L - - - 1800a -Metals -Aluminium mg/L 0.055 5 5 2a -Antimony mg/L 0.009*** - - 0.03h -Arsenic mg/L 0.024 0.1 0.5 0.07h -Barium mg/L - - - 7h -Beryllium mg/L 0.00013*** 0.1 0.073** 0.73** -Boron mg/L 0.37 0.5 5 40h -Cadmium mg/L 0.0002 0.01 0.01 0.02h -Chromium (total) mg/L 0.001 0.1 1 0.5h -Cobalt mg/L 0.0014*** 0.05 1 0.11** -Copper mg/L 0.0014 0.2 0.4 10a -Iron mg/L 0.3*** 0.2 - 3a -Lead mg/L 0.0034 2 0.1 0.1h -Manganese mg/L 1.9 0.2 - 1a -Mercury mg/L 0.0006 0.002 0.002 0.01h -Molybdenum mg/L 0.034*** 0.01 0.15 0.5h -Nickel mg/L 0.011 0.2 1 0.2h -Selenium mg/L 0.011 0.02 0.02 0.1h -Tin mg/L 0.003*** - 22** 220** -Vanadium mg/L - 0.1 0.18** 1.8** -Zinc mg/L 0.008 2 20 30a -Volatile OrganicsMTBE mg/L 51+ 0.02^ - 0.02^ - -PAHs Acenaphthene mg/L - - 2.2** 22** - Anthracene mg/L 0.0004*** - 11** 110** - Benz[a]anthracene mg/L - - 0.000029** 0.00029** - Benzo[a]pyrene mg/L 0.0002*** - 0.00001* 0.0001* - Benzo[b]fluoranthene mg/L - - 0.000029** 0.00029** - Benzo[k]fluoranthene mg/L - - 0.00029** 0.0029** - Chrysene mg/L - - 0.0029** 0.029** - Dibenz[a,h]anthracene mg/L - - 0.0000029** 0.000029** - Fluoranthene mg/L 0.0014*** - 1.5** 15** - Fluorene mg/L - - 1.5** 15** - Indeno[1,2,3-cd]pyrene mg/L - - 0.000029** 0.00029** - Naphthalene mg/L 0.016 - 0.00014** 0.0014** -Phenanthrene mg/L 0.0002*** - - - - Pyrene mg/L - - 1.1** 11** -Total PAH mg/L - - - - -Petroleum HydrocarbonsTPH C6-C9 mg/L - - - - -TPH C10-C36 mg/L 0.6# 0.6# 0.6# 6# -Benzene mg/L 0.95 - 0.001* 0.01h -Toluene mg/L 0.18*** - 0.8* 0.25a -Ethyl Benzene mg/L 0.08*** - 0.3* 0.03a -Total Xylenes mg/L 0.63*** - 0.6* 0.2a -

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Table 2Adopted Groundwater Quality Objectives

Analyte Units

Maintenance of Ecosystems - 95%

Freshwater (based on Urban Waterways

Segment, modified ecosystems) (ANZECC,

2000)

Agriculture, Parks, and Gardens

(ANZECC, 2000)

Stockwatering (ANZECC 2000)

Primary Contact Recreation

(NHMRC 2008)1

Buildings and Structures (AS2159

- 2009)

Industrial Water Use (based on ANZECC 1992, once through

cooling and make-up water)

PhenolsPhenolics mg/L - - - 0.02° -Phenol mg/L 0.32 - - 110** -2 Chlorophenol mg/L 0.49 - - 0.001a -2,4,6 Trichlorophenol mg/L 0.02 - 0.02 -Pentachlorophenol mg/L 0.01 - 0.009¤ 0.09¤ -2,3,4,6 Tetrachlorophenol mg/L 0.02 - - 11* -2 Nitrophenol mg/L 0.002*** - - - -4 Nitrophenol mg/L 0.058*** - - - -Chlorinated HydrocarbonsCarbon tetrachloride mg/L 0.24*** - 0.003* 0.03h -TCE mg/L 0.33*** - 0.002** 0.02** -PCE mg/L 0.07*** - 0.05* 0.5h -cis-1,2-DCE mg/L - - 0.06* 0.6h -1,1-DCE mg/L 0.7*** - 0.03* 0.3h -VC mg/L 0.1*** - 0.0003* 0.003h -1,2,3 Trichlorobenzene mg/L 0.01 - 0.029** 0.29** -1,2,4 Trichlorobenzene mg/L 0.17 - 0.0023** 0.023** -1,3,5 Trichlorobenzene mg/L 0.008*** - - - -1,2,3,4 Tetrachlorobenzene mg/L 0.002*** - - - -1,2,3,5 Tetrachlorobenzene mg/L 0.003*** - - - -1,2,4,5 Tetrachlorobenzene mg/L 0.005*** - 0.0011** 0.011** -HCB mg/L 0.00005*** - - - -OCPsAlpha-BHC mg/L - - - - -Beta-BHC mg/L - - - - -Endosulfan mg/L 0.0002 - - - -Lindane mg/L 0.0002 - 0.02* 0.2h -Heptachlor mg/L 0.00009 - 0.0003* 0.003h -Heptachlor epoxide mg/L - 0.0003* 0.003hAldrin mg/L 0.00008 - 0.0003* 0.003h -DDE mg/L 0.00003*** - - - -DDD mg/L - -Dieldrin mg/L 0.00001*** - 0.0003* 0.003h -DDT mg/L 0.00001 - 0.02* 0.2h -Endrin mg/L 0.00002 - 0.0006¤ 0.006¤ -Methoxychlor mg/L 0.000005*** - 0.3* 3h -Chlordane mg/L 0.00008 - 0.001* 0.01h -Endosulfan alpha mg/L 0.0000002*** - 0.03* 0.3h -Endosulfan beta mg/L 0.000007*** - 0.03* 0.3h -PCBsAroclor 1016 mg/L 0.000001*** - 0.00096** 0.0096** -Aroclor 1221 mg/L 0.001*** - 0.0000068** 0.000068** -Aroclor 1232 mg/L 0.0003*** - 0.0000068** 0.000068** -Aroclor 1242 mg/L 0.0006 - 0.000034** 0.00034** -Aroclor 1248 mg/L 0.00003*** - 0.000034** 0.00034** -Aroclor 1254 mg/L 0.00001*** - 0.000034** 0.00034** -Aroclor 1260 mg/L 0.025*** - 0.000034** 0.00034** -Total PCBs mg/L - - - 0.0001 -

1

h Indicates selected value is 10 × health-based drinking water standarda Indicates selected value is 10 × aesthetic drinking water standard* Australian Drinking Water Guidelines (NHMRC, 2004)

** USEPA, 2010 RSLs (tap water). For primary contact recreation these values have been multiplied by 10.*** Low reliability trigger values - freshwater (ANZECC 2000)

**** Based on brackish water (>1,000-35,000 mg/L), (ANZECC 1992)# Dutch Intervention Guidelines (2000)+ US EPA Fact Sheet - Aquatic Life Criteria for MTBE (March 2006)^

c

¤° Primary contact recreation (ANZECC, 2000)

Unless otherwise stated, values for Primary Contact Recreation have been calculated as drinking water guidelines from NHMRC, 2004, multiplied by a factor of 10 consistent with NHMRC, 2008.

US EPA Fact Sheet - Drinking Water Advisory: Consumer Acceptability Advice and Health Effects Analysis on MTBE (December 1997)Chloride causes foliar injury at different concentrations in crops of varying sensitivity (175 mg/L for sensitive crops; 175 - 350 mg/L for moderately sensitive crops; 35 - 700 mg/L for moderately tolerant crops; >700 mg/L for tolerant cropsWorld Health Organaisation (WHO) Guidelines for Drinking Water Quality (WHO, 2008). For primary contact recreation these values have been multiplied by 10.


Sample Number Sample depth (m) Analyte Result (mg/kg) Beneficial Use Criteria (mg/kg)

Tank Excavation Assessment - June 2003

EW23 3.5 TPH C6-C9 55Human Health - Low Density Residential Human Health - High Density Residential 30

EW23 3.5 TPH C10-C14 760

Maintenance of Ecosystems and Production of food, flora and fibre

Human Health - Low Density Residential 150EW23 3.5 TPH C10-C14 760 Human Health - High Density Residential 600EW23 3.5 TPH C10-C14 760 Human Health - Public Open Space 300EW23 3.5 TPH C10-C14 760 Human Health - Commercial / Industrial 260

EW23 3.5 Ethylbenzene 21Human Health - Low Density Residential Human Health - High Density Residential 5.4

EW23 3.5 Ethylbenzene 21 Human Health - Public Open Space 10.8

EW25 3.5 TPH C6-C9 90Human Health - Low Density Residential Human Health - High Density Residential 30

EW25 3.5 TPH C6-C9 90 Human Health - Public Open Space 60

EW25 3.5 TPH C10-C14 940

Maintenance of Ecosystems and Production of food, flora and fibre

Human Health - Low Density Residential 150EW25 3.5 TPH C10-C14 940 Human Health - High Density Residential 600EW25 3.5 TPH C10-C14 940 Human Health - Public Open Space 300EW25 3.5 TPH C10-C14 940 Human Health - Commercial / Industrial 260

EW25 3.5 Total PAHs 18.7Maintenance of Ecosystems and Production

of food, flora and fibre 18

Further Tank Excavation Assessment - March - July 2005TA-N2 3.2 Benzo(a)pyrene 1.99 Human Health - Low Density Residential 1

TA-B2 (6/6) 3.5 TPH C6-C9 110Human Health - Low Density Residential Human Health - High Density Residential 30

TA-B2 (6/6) 3.5 TPH C6-C9 110 Human Health - Public Open Space 60

Soil Validation Assessment - January 2007 - June 2008

TIT-B4 2.3 Barium 370Maintenance of Ecosystems and Production


EXB-B2 4 Barium 340Maintenance of Ecosystems and Production


EXB-B2 4 Vanadium 71Maintenance of Ecosystems and Production


EXB-B4 4.5 Vanadium 65Maintenance of Ecosystems and Production


EXB-WW1 2 Vanadium 75Maintenance of Ecosystems and Production


TP1-B1 3 Vanadium 67Maintenance of Ecosystems and Production


TP1-B2 3 Vanadium 71Maintenance of Ecosystems and Production


TB-B8 3 Vanadium 77Maintenance of Ecosystems and Production






TB-B12 1.5 Vanadium 82Maintenance of Ecosystems and Production


TB-NW2 1 Vanadium 66Maintenance of Ecosystems and Production




TB-NW5 0.5 Vanadium 72Maintenance of Ecosystems and Production


Table 3Exceedences of Adopted Soil Criteria After Remediation/Validation

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Table 3 Soil Exceedances.xls







EXC-B2 5 Nickel 70Maintenance of Ecosystems and Production


EXC-B3 3.2 Vanadium 120Maintenance of Ecosystems and Production


EXC-B5 4 Nickel 66Maintenance of Ecosystems and Production


EXC-B6 1.5 Vanadium 50Maintenance of Ecosystems and Production


EXC-NW1 3.5 Vanadium 56Maintenance of Ecosystems and Production


EXC-NW2 3 Arsenic 22Maintenance of Ecosystems and Production


EXC-NW2 3 Vanadium 193Maintenance of Ecosystems and Production


EXC-NW3 3 Vanadium 70Maintenance of Ecosystems and Production


EXC-B9 3 Vanadium 67Maintenance of Ecosystems and Production


EXC-B12 2 Vanadium 57Maintenance of Ecosystems and Production


EXC-WW2 2 TPH C15-C36 465 Human Health - Low Density Residential 300

EXC-WW2 2 Vanadium 92Maintenance of Ecosystems and Production


EXD-B1 2.2 Barium 380Maintenance of Ecosystems and Production






EXD-EW2 1 Vanadium 58Maintenance of Ecosystems and Production


TB-B16 1.7 Barium 720Maintenance of Ecosystems and Production


TB-EW17 1.7 Vanadium 66Maintenance of Ecosystems and Production


TB-B18 2.3 Barium 730Maintenance of Ecosystems and Production


TB-EW19 1.5 Barium 340Maintenance of Ecosystems and Production


TB-EW21 0.5 Barium 310Maintenance of Ecosystems and Production


TB-NW10 2.5 Barium 430Maintenance of Ecosystems and Production












TB-B29 1.6 Nickel 87Maintenance of Ecosystems and Production




TB-B29 1.6 Manganese 655Maintenance of Ecosystems and Production






TB-WW6 0.5 Copper 174Maintenance of Ecosystems and Production


TB-WW6 0.5 Vanadium 59Maintenance of Ecosystems and Production




TB-EW27 1.3 Vanadium 50Maintenance of Ecosystems and Production




IF-1 NDCR Backfill Vanadium 54Maintenance of Ecosystems and Production


IF-2 NDCR Backfill Manganese 540Maintenance of Ecosystems and Production
















IF-11 NDCR Backfill Vanadium 52Maintenance of Ecosystems and Production






IF-26 NDCR Backfill Arsenic 20Maintenance of Ecosystems and Production








IF-44 NDCR Backfill Nickel 94Maintenance of Ecosystems and Production


IF-44 NDCR Backfill Chromium 110 Human Health- Low Density Residential 100

IF-46 NDCR Backfill Barium 1680Maintenance of Ecosystems and Production


IF-46 NDCR Backfill Nickel 136Maintenance of Ecosystems and Production

of food, flora and fibre 60IF-46 NDCR Backfill Cobalt 228 Human Health- Low Density Residential 100

IF-46 NDCR Backfill Cobalt 228 Human Health- Public Open Space 200













Post Phase 2 ESA - July/August 2008

MW8-6.0 6.0 Nickel 62Maintenance of Ecosystems and Production


Post Phase 2 ESA - April 2009

SB11_0.2 0.2 Nickel 67Maintenance of Ecosystems and Production


SB11_0.5 0.5 Vanadium 159Maintenance of Ecosystems and Production


Further Tank Excavation Assessment - February 2010

BF_1 NDCR Backfill Manganese 559Maintenance of Ecosystems and Production


ExE_V1 1.5 Vanadium 62Maintenance of Ecosystems and Production









of food, flora and fibre 50ExE_V18 0.3 Benzo(a)pyrene 1.6 Human Health - Low Density Residential 1



ExE_V19 2.4 Barium 340Maintenance of Ecosystems and Production





of food, flora and fibre 50ExE_V21 1.5 TPH C15-C36 520 Human Health - Low Density Residential 300ExE_V22 1.5 Benzo(a)pyrene 1.3 Human Health - Low Density Residential 1


of food, flora and fibre 51ExE_V24 0.3 Benzo(a)pyrene 1.9 Human Health - Low Density Residential 1

ExE_V24 0.3 Zinc 281Maintenance of Ecosystems and Production

of food, flora and fibre 200ExE_V25 0.3 TPH C15-C36 390 Human Health - Low Density Residential 300ExE_V25 0.3 Benzo(a)pyrene 6.9 Human Health - Low Density Residential 1ExE_V25 0.3 Benzo(a)pyrene 6.9 Human Health - High Density Residential 4ExE_V25 0.3 Benzo(a)pyrene 6.9 Human Health - Public Open Space 2ExE_V25 0.3 Benzo(a)pyrene 6.9 Human Health - Commercial / Industrial 5

ExE_V25 0.3 Total PAHs 73.2Maintenance of Ecosystems and Production

of food, flora and fibre 18ExE_V25 0.3 Total PAHs 73.2 Human Health - Low Density Residential 20ExE_V25 0.3 Total PAHs 73.2 Human Health - Public Open Space 40



Table 4Exceedances of Adopted Groundwater Quality Objectives after Remediation/Validation

Sample Location Date Analyte Result (ug/L) Beneficial Use GWQO

MW5 15/07/2010 MTBE 202Agriculture, parks and gardens;

Primary contact recreation 20MW7 24/02/2010 Sulphate 9020 mg/L Stockwatering 1000MW7 24/02/2010 Sulphate 9020 mg/L Primary contact recreation 2500MW7 24/02/2010 Sulphate 9020 mg/L Buildings and structures 1000MW7 24/02/2010 Sulphate 9020 mg/L Industrial water use 2700


Primary contact recreation 20


Primary contact recreation 20


Primary contact recreation 20MW11 25/02/2010 Sulphate 6830 mg/L Stockwatering 1000MW11 25/02/2010 Sulphate 6830 mg/L Primary contact recreation 2500MW11 25/02/2010 Sulphate 6830 mg/L Buildings and structures 1000MW11 25/02/2010 Sulphate 6830 mg/L Industrial water use 2700MW17 24/02/2010 Sulphate 1490 mg/L Stockwatering 1000



43512483/R001/A

Figures

Figure 1 Site Locality Plan

Figure 2 Site Features Plan

Figure 3 Groundwater Contour Plan (November 2010)

Figure 4 Registered Groundwater Bore Locations (Statewide Groundwater Database)

Figure 5 Handex Soil and Groundwater Well Locations

Figure 6 Former UST Locations and ITE Excavation Extents (2003)

Figure 7a Excavation Extents (March 2005)

Figure 7b Excavation Extents (May 2005)

Figure 7c Excavation Extents (June 2005)

Figure 7d Excavation Extents (July 2005)

Figure 8 Final Excavation Extents (2007 – 2010)

Figure 9 Residual Soil Contamination in NE Corner of Site (February 2010)

Figure 10 Groundwater Quality Restricted Use Zone (GQRUZ)


43512483/R001/A

Plates

Plate 1 16 February 2010: Widening of St Georges Road (eastern site boundary)

Plate 2 16 February 2010: Retaining wall along the western site boundary

Plate 3 16 February 2010: NDCR backfill across the site

Plates

16 February 2010: Retaining wall along the western site boundary

Plate 1

Plate 2

16 Febraury 2010: Widening of St Georges Road (eastern site boundary)

URS Australia Pty Ltd 1 of 2\\mel-fs\jobs\JOBS\43512483\Reporting\Audit\Plates\

Northcote audit plates.xls

Plates

Plate 3

16 February 2010: NDCR backfill across the site

URS Australia Pty Ltd 2 of 2\\mel-fs\jobs\JOBS\43512483\Reporting\Audit\Plates\

Northcote audit plates.xls

r001 mobil northcote audit report...

Documents