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Mobil Oil Australia Pty Ltd 14 December 2012

Environmental Audit Report: Implementation of Groundwater Quality Management Plan (GQMP) Former Scoresby Fuelzone, 1271 Ferntree Gully Road, Scoresby, Victoria

AECOM

Environmental Audit Report: Implementation of Groundwater Quality Management Plan (GQMP)

14 December 2012

Environmental Audit Report: Implementation of Groundwater Quality Management Plan (GQMP) Former Scoresby Fuelzone, 1271 Ferntree Gully Road, Scoresby, Victoria

Prepared for

Mobil Oil Australia Pty Ltd

Prepared by AECOM Australia Pty Ltd Level 9, 8 Exhibition Street, Melbourne VIC 3000, Australia T +61 3 9653 1234 F +61 3 9654 7117 www.aecom.com ABN 20 093 846 925

14 December 2012

60248176

AECOM in Australia and New Zealand is certified to the latest version of ISO9001 and ISO14001.

© AECOM Australia Pty Ltd (AECOM). All rights reserved.

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14 December 2012

Quality Information Document Environmental Audit Report: Implementation of Groundwater Quality Management

Plan (GQMP)

Ref 60248176

Date 14 December 2012

Project Manager Averyll Coyne

Project Director Darryl Strudwick

Reviewed by Darryl Strudwick

Revision History

Revision Revision Date Details

Authorised

Name/Position Signature

0 14 Dec 2012 Final Darryl Strudwick – Environmental Auditor (Contaminated Land)

1

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Table of Contents Executive Summary i 1.0 Introduction 1

1.1 Background 1 1.2 Environmental Audit (2012) 2

2.0 Audit Scope and Methodology 3 2.1 Audit Objectives, Scope and Methodology 3 2.2 Documents Reviewed 5 2.3 Guidance Documents 5 2.4 Parties Involved 6 2.5 Auditors Support 6 2.6 Site Visit 6

3.0 Site Description and Layout 7 3.1 Site Description 7 3.2 Planning Scheme 7 3.3 Geology and Hydrogeology 7

3.3.1 Regional Geology 7 3.3.2 Site Geology 8 3.3.3 Regional Hydrogeology 8 3.3.4 Site Hydrogeology 8

4.0 Groundwater Quality Management Plan (GQMP) 10 4.1 Introduction 10 4.2 Auditor Review of Groundwater Monitoring in accordance with the GQMP 10 4.3 Adequacy of GQMP 16

4.3.1 Stability and behaviour of the plume 16 4.3.2 Triggers and contingencies 16 4.3.3 Process to determine an increase in plume extent and/or concentration levels 17 4.3.4 Does the monitoring program address all of the risks posed by groundwater

contamination from the premises? 17 5.0 Groundwater Quality at the Site 18

5.1 Groundwater Monitoring Data 18 5.2 Summary 20

6.0 Assessment of Risk to Beneficial Uses of Land and Groundwater 21 6.1 Introduction 21

6.1.1 Previous Audit (URS, 2007) 21 6.1.2 Risk to Beneficial Uses of Land and Groundwater during the GQMP period 22

6.2 Land 22 6.2.1 SEPP (Prevention and Management of Contamination of Land) 22 6.2.2 Assessment of Risk to Human Health 23

6.3 Groundwater 23 6.3.1 Perched water 23 6.3.2 Regional Aquifer 23 6.3.3 Assessment of Risk to Beneficial Uses of Groundwater 24

7.0 Conclusions and Recommendations 26 7.1 Conclusions 26 7.2 Recommendations 28

8.0 References 29 9.0 Limitations 31 Appendix A

Figures prepared by Coffey Environments A Appendix B

Property Report and Land Use Zoning B Appendix C

Determination of Clean Up of Groundwater to the Extent Practicable (EPA Victoria, 22 September 2011) C

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Appendix D Draft Pollution Abatement Notice (EPA Victoria, 2011) D

Appendix E Groundwater Quality Management Plan (GQMP) – Coffey, 2008 E

Appendix F 2012 Auditor Review of Former Mobil Scoresby Fuelzone Groundwater Monitoring Requirements (26 June 2012) F

Appendix G EPA Approval of Audit Scope G

Appendix H Historical Groundwater Monitoring Results, Perched and Regional Groundwater – 2004 to 2011 H

Appendix I Contaminant Contours, Benzene, C6-C9, C10-C36, Perched and Regional Groundwater – 2004 to 2011 I

Appendix J Search of the Victorian Groundwater Database J

Appendix K 2003 to 2011 Groundwater Charts – Groundwater Elevation and Hydrocarbon Concentrations K

List of Tables

Table 1 Summary of Audit Information

Table 2 Audit Objectives, Scope and Methodology

Table 3 Auditor Site Visits

Table 4 Surrounding Land Use

Table 5 Findings of the Auditor’s Review conducted in June 2012

Table 6 Beneficial Uses of Groundwater protected in Segment B

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Executive Summary Table 1 Summary of Audit Information

EPA File Reference No. 65300-2

Auditor Darryl Strudwick

Auditor Term of Appointment 18 November 2007 – 24 July 2015

Name of person requesting the Audit Mr Luis Cifuentes, CTC Program Manager, Mobil Oil Australia Pty Ltd

Relationship to premises/location Representative of former site occupier (Mobil Oil Australia Pty Ltd)

Date of request 02 / 08 / 2012

Date EPA notified of Audit 15 / 08 / 2012

Completion date of the Audit 14 / 12 / 2012

Reason for Audit To assess implementation of GQMP and whether groundwater monitoring at the site can cease.

Description of Activity

Activities undertaken in accordance with the GQMP. Risk of any possible harm to beneficial uses of land and/or groundwater caused by residual hydrocarbon contamination at the site.

EPA region South Metropolitan

Dominant - Lot on plan Lot 2 on Plan Number PS402800

Additional - Lot on plan(s) NA

Site/premises name NA

Buidling/complex sub-unit No. NA

Street/Lot - Lower No. NA

Street/Lot Upper No. 1271

Street Name Ferntree Gully

Street type (road, court etc) Road

Street suffix (north, south etc) NA

Suburb Scoresby

Postcode 3179

GIS coordinate of site centroid (GDA94):

Longitude/northing 145.221944

Latitude/Easting 37.89889

Member and categories of support team utilised No additional support team utilised

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EPA File Reference No. 65300-2

Outcome of Audit See conclusions and recommendations (Sections 7.1 and 7.2)

Further work or requirements Implement recommendations in Section 7.2

Groundwater segment A2 and B

Surrounding land use

North - Commercial Properties and stormwater drainage reserve

East - Cathies Lane reserve (Plate 3) and residential properties (note that residential properties are located 30 m from the south eastern site boundary)

South - Ferntree Gully Road and commercial/industrial properties

West - Commercial/industrial properties including “Tyre

Power”

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1.0 Introduction This Environmental Audit Report has been prepared by Mr. Darryl Strudwick (an EPA appointed Environmental Auditor – Contaminated Land) of AECOM Australia Pty Ltd (AECOM), at the request of Mr. Luis Cifuentes of Mobil Oil Australia Pty Ltd (Mobil).

This report has been prepared pursuant to section 53V of the Environment Protection Act 1970, and relates to the former Scoresby Fuel Zone service station (the site), located at 1271 Ferntree Gully Road, Scoresby, Victoria (Refer to Coffey’s figure titled ‘Site Locality Plan (August 2008)’ No. ENVIABTF07066XA-D01 – Appendix A). The site is currently operating as a ‘United’ Service Station facility and occupies an area of approximately 2,870

m2. The site is zoned Industrial (IN1 Zone) under the City of Knox planning scheme (Appendix B), and the surrounding land-uses are predominantly commercial/industrial, residential, public space and a drainage reserve.

1.1 Background

In September 2000, petroleum hydrocarbons were identified in the stormwater pits and drains at and adjacent to the site. Consequently, EPA Victoria issued a Clean Up Notice (dated 19 September 2000) which required immediate action to prevent further environmental impact. Stormwater remediation works were undertaken by Petro Quip Australia Pty Ltd (Petro Quip) in late 2000, which consisted of the installation and implementation of a stormwater treatment system.

Subsequent investigations undertaken by Petro Quip found that petroleum hydrocarbons were entering the stormwater system through the sub-surface in the southwest corner of the site. Soil and groundwater contamination was also found to exist as a result of petroleum storage, handling and related activities at the site. The primary source of petroleum hydrocarbon loss to the sub-surface was thought to be through unsuitable joins in the piping at remote fill points in the western portion of the site.

As a result of a condition of a second Clean Up Notice (issued by EPA Victoria on 15 July 2003), an Environmental Audit was conducted by Mr Peter Mirkov (IT Environmental Pty Ltd) in September 2003 to assess the risk to beneficial uses of land and/or groundwater. The Audit concluded that soil pollution at the site (prior to remediation) precluded the beneficial uses associated with ongoing commercial and industrial use. The Auditor also concluded that groundwater pollution precluded the beneficial uses of groundwater and that the site may potentially pose an unacceptable long term risk to human health. Recommendations were also made in relation to the preparation of a remedial action plan to restore the beneficial uses of land and groundwater.

A further Clean Up Notice was issued by EPA Victoria on 18 of November 2003 which required the commencement of the recommended clean up works on or before 1 December 2003. Between 21 November 2003 and 26 June 2004, remediation works were undertaken, which included excavation, storage and disposal of contaminated soil (approximately 4,650 tonnes), removal and replacement of underground storage tanks (USTs) and associated infrastructure. A total of approximately 4,500 L of free phase petroleum hydrocarbon and approximately 789,750 L of contaminated water were also removed from the tank pit and stormwater treatment system during the remedial works. The stormwater drainage pipe running along the southern side of the site was replaced at the time of remedial works.

Requirement 5 of the Clean Up Notice (dated 18 November 2003) required an Environmental Audit (post remediation) in relation to the risk of any possible harm or detriment to the beneficial uses of land and/or groundwater caused by petroleum storage and handling and related activities at the premises. On 2 August 2004, Mr Darryl Strudwick was engaged by Mobil to undertake the post remediation Audit.

Following discussions with EPA Victoria, Requirement 5 was addressed in two separate Audit reports, one in relation to the stormwater component and the other in relation to land and groundwater. An Audit report entitled “Stormwater Component – Environmental Audit Former Scoresby Fuel Zone, 1271 Ferntree Gully Road,

Scoresby Victoria” was finalised on 15 March 2005 (URS, 2005). The second Audit report titled “Environmental

Audit, Former Scoresby Fuel Zone, 1271 Ferntree Gully Road, Scoresby Victoria” (relating to an assessment of risk to the groundwater and land environments caused by contamination at the site) was issued in October 2007 (URS, 2007).

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Condition 6 of the Clean Up Notice Clean Up Notice (dated 18 November 2003) required that the Audit report include an opinion as to whether groundwater had been cleaned up to the extent practicable (CUTEP). After assessing the technical, logistical and financial considerations associated with a number of remedial techniques, the Auditor concluded that CUTEP had not occurred, as there were remedial options (such as MPVE) that he considered at the time were practicable, commensurate with the environmental significance of the contamination at the site.

A series of multi-phase vapour extraction (MPVE) events were then undertaken at groundwater wells containing the highest hydrocarbon concentrations in the southeast of the site to assess the potential effectiveness of this technology and reduce the mass of hydrocarbons in groundwater at the site. Based on the results of these events, the Auditor forwarded a formal CUTEP submission to EPA on 8 January 2009 (URS, 2009). The submission concluded that, in the Auditors opinion, CUTEP had been achieved, as the most practicable remedial technology had been trialled and found to not to be practicable at the site, commensurate with the environmental significance of the pollution.

CUTEP was determined by EPA Victoria for the site on 22 September 2011 (Appendix C). EPA attached a number of requirements to the CUTEP determination, including:

- A detailed groundwater quality management plan (GQMP) identifying a s53V Audit as the appropriate mechanism for cessation of groundwater management and monitoring.

EPA subsequently issued a draft Pollution Abatement Notice (PAN) (Appendix D), with the intention of ensuring that ongoing groundwater monitoring occurred at the site to “confirm the stability and behaviour of the plume and to set triggers and contingencies for addressing any changes in conditions at the premises”.

A Groundwater Quality Management Plan (GQMP) had previously been prepared by Coffey Environments (Coffey, 2008) following a recommendation to prepare and implement a GQMP in the Audit Report (URS, October 2007). The GQMP was attached to the Auditor’s CUTEP submission to EPA (URS, 2009). A copy of the GQMP attached as Appendix E of this Audit report. Groundwater monitoring events in accordance with the GQMP have been undertaken in August 2008, February 2009, August 2009, February 2010, September 2010 and June/July 2011. Data from these Groundwater Monitoring Events (GMEs) were incorporated into the various responses to EPA queries relating to the CUTEP submission.

Following a meeting between Mobil and EPA Victoria on 21 February 2012 to discuss the requirements of the draft PAN and the existing GQMP, EPA requested that an Environmental Auditor review the groundwater monitoring completed in accordance with the GQMP and assess whether it meets the requirements 3.1 and 3.2 of the draft PAN. Darryl Strudwick of AECOM (an appointed EPA Environmental Auditor) was engaged by Mobil to undertake this review. The review was completed on 26 June 2012 (attached as Appendix F) and concluded that the GQMP (Coffey, 2008) has been implemented and that groundwater quality at and down hydraulic gradient of the site has remained relatively consistent throughout the monitoring period. The Auditor recommended a Section 53V Environmental Audit is commenced, which will assess the risk posed by the residual contamination at and from the Site and make formal recommendations relating to ongoing management of polluted groundwater (including monitoring) in accordance with EPA Publication 840. On 8 August 2012, EPA confirmed that on the basis of the review, a s53V Environmental Audit is the appropriate mechanism to confirm if groundwater monitoring can cease.

1.2 Environmental Audit (2012)

Mr. Darryl Strudwick (a person appointed as an Environmental Auditor, pursuant to the Environment Protection

Act 1970) of AECOM was engaged by Mr. Luis Cifuentes of Mobil Oil Australia Pty Ltd on 2 August 2012 to undertake this s53V Environmental Audit. The Auditor notified EPA Victoria of the request to prepare an Audit Report on 15 August 2012 in accordance with Section 5 of the Environmental Auditor Guidelines for the Preparation of Environmental Audit Reports on Risk to the Environment (EPA Victoria publication 952.2, August 2007).

The proposed objectives and scope of the Audit were forwarded to EPA Victoria on 15 August 2012 in accordance with Section 8 of Environmental Auditor Guidelines for the Preparation of Environmental Audit Reports on Risk to the Environment (EPA Victoria Publication 952.2, August 2007).

The scope was approved by EPA Victoria in writing on 27 August 2012 (See Appendix F).

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2.0 Audit Scope and Methodology

2.1 Audit Objectives, Scope and Methodology

The objectives, scope and methodology for the Audit are provided in Table 2 (as forwarded to EPA Victoria on 15 August 2012 and accepted by EPA Victoria on 22 August 2012). Table 2 Audit Objectives, Scope and Methodology

Environmental Audit Objectives and Scope

Audit Objectives

- To assess whether groundwater monitoring has been undertaken in accordance with the Groundwater Quality Management Plan (GQMP) for the site.

- To review the groundwater monitoring data collected in accordance with the GQMP and assess whether the risks associated with groundwater quality at the site are unchanged.

- To identify whether further groundwater monitoring is necessary at the site.

Audit Scope

Activity - Activities undertaken in accordance with the GQMP. Risk of any possible harm

to beneficial uses of land and/or groundwater caused by residual hydrocarbon contamination at the site.

Components - Groundwater monitoring network. - Groundwater monitoring in accordance with GQMP.

Segment to be audited - The area within the boundaries of the site (Lot 2 on Plan Number PS402800) and

off-site areas potentially subject to risks associated with residual groundwater contamination.

Elements to be considered The elements of the environment to be considered through this Audit are: - Groundwater underlying the site and surrounds. - Land potentially affected by the groundwater quality.

Beneficial uses

Groundwater: The groundwater at the site has previously been classified as wthin Segment B (in accordance with the State Environment Protection Policy Groundwaters of Victoria 1997). The beneficial uses of groundwater to be protected for Segment B are: - Maintenance of Aquatic Ecosystems. - Potable mineral water supply. - Agriculture, parks and gardens. - Stock watering. - Industrial water use. - Primary contact recreation (e.g. bathing, swimming). - Buildings and structures. As detailed in previous reports, 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 applicable. Additionally, previous reports have observed that the chemicals of potential concern (CoPC) at this site are not likely to be harmful to the buildings and structures and are therefore not applicable. Land: The Audit will also assess the potential risk posed by the groundwater quality at the site during the monitoring period to the beneficial use of land - human health.

Risk Assessment - Comparison of soil and groundwater quality against the environmental quality

objectives of the relevant SEPPs. - Consideration of the likelihood of beneficial uses being realised.

Expected Completion Date 31 August 2012

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Environmental Audit Objectives and Scope

Exclusions

The Audit will not include: - Risks to the air environment (and beneficial uses) potentially caused by the

ongoing use of the site as a petroleum service station. - Risks posed to beneficial uses of land and groundwater caused by past activities

at the site that do not relate to petroleum service use.

Audit criteria

- Groundwater quality criteria for the parameters analysed (BTEX, TPH and Pb) adopted for the previous Audit of the site and stipulated within the GQMP.

Other relevant criteria documented in the following publications: - State Environment Protection Policy Groundwaters of Victoria, Victorian

Government Gazette, No. S160, December 1997. - State Environment Protection Policy (Prevention and Management of

Contamination of Land), Victorian Government Gazette, No. S95, June 2002. - Variation to State Environment Protection Policy (Waters of Victoria), Victorian

Government Gazette, No. S107, June 2003. - National Environment Protection (Assessment of Site Contamination) Measure

Guideline on the Investigation Levels for Soil and Groundwater, National Environment Protection Council, December 1999.

- Groundwater Sampling Guidelines (EPA Publication 669, April 2000). - Sampling and Analysis of Water, Wastewaters, Soils and Wastes (Inustrial Waste

Resource Guidelines, Publication 701, 2009). - Environmental Auditor Guidelines for the Preparation of Environmental Audit

Reports on Risk to the Environment (EPA Publication 952.2, August 2007)

Methodology

- Assess the adequacy of the GQMP: That is: Prepared in accordance with EPA Guidelines and expectations (e.g.

Publication 840). It confirms the stability and behaviour of the plume and sets triggers and

contingencies for addressing any changes in conditions at the premises. It has a process to determine any increase in plume extent and/or

concentration levels which could constitute a risk to human health or the environment, including contingencies related to remediation activities, if necessary.

The environmental monitoring program addresses all of the risks posed by groundwater contamination from the premises.

- Assess compliance of groundwater monitoring and analytical results with the GQMP.

- Identify CUTEP requirements at the time of CUTEP and assess whether CUTEP requirements have since been met.

- Risk Assessment: Assess the potential for risk to the beneficial uses of groundwater and land

(subject to the adequacy of the groundwater monitoring and analytical results), including the consideration of the likelihood of beneficial uses being realised.

- Preparation of a s53V Audit Report The following documents will be reviewed in detail: - Groundwater Quality Management Plan, Former Mobil Service Station, Scoresby

(Coffey, October 2008b). - The GME reports undertaken in accordance with the GQMP and historical data. - CUTEP information: Auditor submissions to EPA, comments from EPA and

Auditor responses. - CUTEP letter from EPA Victoria. - 2012 Auditor Review of Former Mobil Scoresby Fuelzone Groundwater

Monitoring Requirements (26 June 2012). Member and Categories of Proposed Support Team

Ms. Amanda Lee: (Environmental Chemistry – Analytical (Human Toxicology])

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2.2 Documents Reviewed

The Audit involved the review of the following documents:

- Environmental Audit Former Scoresby Fuelzone, 1271 Ferntree Gully Road, Scoresby Victoria (URS, October 2007);

- Interim Groundwater Monitoring Event Report (Coffey, October 2008);

note that field work for this GME was conducted in August 2008;

- Groundwater Quality Management Plan, Former Mobil Service Station, Scoresby (Coffey, October 2008) (Appendix E);

- E-mail correspondence between Coffey, the Auditor and Mobil relating to the GQMP (Coffey, 2008) and groundwater management requirements in the CUTEP submission (URS, 2009);

- Auditor’s CUTEP submission to EPA (URS, 8 January 2009);

- Interim Groundwater Monitoring Event Report (Coffey, March 2009);

note that field work for this GME was conducted in February 2009;

- Scoresby CUTEP-Response to EPA query_23_03_09 (URS, 23 March 2009);

- Letter addressed to EPA Victoria with response to questions on CUTEP (URS, 6 April 2009);

- Interim Groundwater Monitoring Event Report (Coffey, October 2009);

note that field work for this GME was conducted in August 2009;

- Former Scoresby Fuelzone, 1271 Ferntree Gully Road, Scoresby, Victoria – Further response to EPA queries on CUTEP Submission (URS, 26 March 2010);

- Interim Groundwater Monitoring Event Report (Coffey, April 2010);

note that field work for this GME was conducted in February 2010;

- Interim Groundwater Monitoring Event Report (Coffey, September 2010);

note that field work for this GME was conducted in September 2010;

- Former Scoresby Fuelzone, 1271 Ferntree Gully Road, Scoresby, Victoria – Additional Response to EPA queries on CUTEP Submission CARMS 65300.1 (URS, 25 October 2010);

- Post Phase 2 ESA August/September 2010 (Coffey, 30 November 2010);

- Interim Groundwater Monitoring Event Report (Coffey, September 2011);

note that field work for this GME was conducted in June/July 2011;

- Determination of Clean Up of Groundwater to the Extent Practicable – 1271 Ferntree Gully Road, Scoresby (EPA Victoria, 22 September 2011) (Appendix C);

- Draft Pollution Abatement Notice (EPA Victoria, 2011) (Appendix D);

- 2012 Auditor Review of Former Mobil Scoresby Fuelzone Groundwater Monitoring Requirements (26 June 2012) (Appendix F).

- Historical Groundwater Monitoring Results, Perched and Regional Groundwater – 2003 to 2011 (Coffey, 2011 – Appendix H);

- Contaminant Contours, Benzene, C6-C9, C10-C36, Perched and Regional Groundwater – 2004 to 2011 (Coffey, 2012) (Appendix I);

- 2003 – 2011 Groundwater Charts – Groundwater Elevation and Hydrocarbon Concentrations (Appendix K).

2.3 Guidance Documents

In undertaking this Audit, the Auditor has had regard to:

- EPA Publication 840, The Clean up and Management of Polluted Groundwater, April 2002, 16pp;

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- EPA Publication 952.2, Environmental Auditor Guidelines for the Preparation of Environmental Audit Reports

on Risk to the Environment, August 2007;

- Government of Victoria, State Environment Protection Policy (Groundwaters of Victoria), Victorian Government Gazette, No. S160, December 1997;

- Government of Victoria, State Environment Protection Policy (Waters of Victoria), Victorian Government Gazette, No. S107, June 2003;

- Government of Victoria, State Environment Protection Policy (Prevention and Management of Contaminated

Land), Victorian Government Gazette, No. S95, June 2002.

- National Environment Protection Council (NEPC), ‘National Environment Protection (Assessment of Site

Contamination) Measure’ 1999;

- National Health and Medical Research Council and the National Resource Management Ministerial Council (2011) National Water Quality Management Strategy - Australian Drinking Water Guidelines 6 – 2011; and

- Australian and New Zealand Environment and Conservation Council (ANZECC) and ARMCANZ, 2000. Australian and New Zealand guidelines for fresh and marine water quality.

2.4 Parties Involved

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

Owner of the site: United Petroleum

Former Site Lessee: Mobil Oil Australia Pty Ltd

Environmental Site Assessor/s: Coffey Environments (Coffey)

Primary Laboratory used by Assessor: Amdel Pty Ltd (Amdel)

Environmental Auditor: Darryl Strudwick (AECOM Pty Ltd)

2.5 Auditors Support

The Auditor has principally relied upon his own expertise in hydrogeology, fate and transport of contaminants in the subsurface, the interpretation of chemical data and assessment of impacts on groundwater in undertaking this Audit.

Additional personnel utilised by the Auditor to complete the Audit are presented below.

- Averyll Coyne (Senior Environmental Scientist) – Project co-ordination and management, site inspection and reporting under the instruction of the Auditor.

- Dr Belinda Goldsworthy (Principal Scientist) – Advised with respect to risks to Human Health.

2.6 Site Visit

The details of the site visit undertaken as part of this Audit are provided in Table 3 below. Table 3 Auditor site visits

Date Personnel Purpose of visit

29 August 2012 Darryl Strudwick (AECOM)

Averyll Coyne (AECOM)

- To allow the Auditor to visually inspect the site layout and gain an up to date spatial awareness of the site and surrounding land uses.

- To observe the location and condition of groundwater monitoring wells and soil vapour bores on and off-site.

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3.0 Site Description and Layout

3.1 Site Description

The former Scoresby Fuel Zone service station (the site) being audited is located at 1271 Ferntree Gully Road, Scoresby, Victoria (Refer to Coffey’s figure titled ‘Site Locality Plan (August 2008)’ No. ENVIABTF07066XA-D01 – Appendix A). The site is currently operating as a ‘United’ Service Station facility, occupying an area of approximately 2,870 m2 and is approximately rectangular in shape. The site is described as Lot 2A on Plan Number PS402800 (Appendix B).

The topography of the site is generally flat, while the regional topography has a gentle slope to the southwest towards Dandenong Creek. The nearest surface water receptors are Dandenong Creek, located approximately 1 km to the west of the site and Caribbean Lake, located just under 1 km southeast of the site. Corhanwarrabul Creek runs parallel to Caribbean Lake which subsequently joins with Dandenong Creek, to the north of Wellington Road.

The following key observations were made during a site inspection conducted by the Auditor on 29 August 2012:

- The buildings on the site consisted of a service station salesroom/store and former car wash area;

- The majority of the site was paved, with only minor landscaped areas (Plate 1) located on the southern and eastern portions of the site, as well as around the former car wash area (north of the site);

- A canopy was observed over the top of eight bowsers (Plate 2);

- There was no evidence of surface spills or leakage on the site; and

- All on and off-site groundwater wells to be monitored in accordance with the GQMP were located, including the GQRUZ delineation wells (i.e. MW16, MW18, MW19, MW19A, MW23, MW26, MW27, MW28, MW28A, MW29, MW29A, MW30A, MW31, MW32, MW33, MW34, MW35, MW36, MW37, MW38, MW39, MW40, MW41, MW42, MW43, MW44, MW45, MW46, MW47, MW48, MW49, MW52, MW52A, MW53, MW54A, MW55A and MW56).

The surrounding land use, as observed on 29 August 2012, is described in Table 4 below.

Table 4 Surrounding Land Use

Direction Land Use

North Commercial Properties and stormwater drainage reserve

East Cathies Lane reserve (Plate 3) and residential properties (note that residential properties are located 30 m from the south eastern site boundary)

South Ferntree Gully Road and commercial/industrial properties

West Commercial/industrial properties including “Tyre Power”

3.2 Planning Scheme

The site is situated within the City of Knox Municipality and is zoned Industrial 1 zoned (IN1Z) in the City of Knox Planning Scheme (See Appendix B). The main purpose of this zone is to provide for manufacturing industry, the storage and distribution of goods and associated uses in a manner which does not affect the safety and amenity of local communities (Department of Planning and Community Development (DPCD), 2012)

3.3 Geology and Hydrogeology

3.3.1 Regional Geology

According to the Geological Survey of Victoria 1:63,360 (Ringwood) and1:250,000 (Melbourne) geological map sheets, the site is underlain by Quaternary alluvial deposits (Qra), comprising silt, sands and gravels. The Quaternary deposits are underlain by the Lower Devonian Humevale Formation which comprises thinly-bedded marine siltstones with sandstones interbedded at the base of the Formation.

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3.3.2 Site Geology

The maximum reported depth of investigation at the site is 5.7 meters below ground level (mBGL) in MW08 (now decommissioned). Varying thicknesses of fill (up to 2 mBGL) has previously been reported across the site. The fill is reported to be thickest off-site, in MW30 and MW31 which are located at and approximately 10-15 m to the southeast of the site respectively. Refer to Coffey’s figure titled ‘Groundwater Quality Restricted Use Zone

(January 2009)’ in Appendix A for these groundwater wells in relation to the property boundary. The fill layer has since been removed across the site as part of the remediation works and does not exist over the central portion of the site. The fill comprises grey/black silts and orange clays with coarse gravels and brick fragments. The bore logs (compiled in URS, October 2007) show that the fill is underlain by orange/grey moist, plastic clay. This clay material appears to be logged in some wells as clayey silt.

3.3.3 Regional Hydrogeology

The site is located within the Dandenong Creek catchment. The closest registered groundwater well is located approximately 820 m east/northeast of the site. It is reported as being 53 m deep and is likely to be screened within the Lower Devonian aquifer. There was no available information regarding the use of this registered groundwater well.

The upper alluvial deposits consist of silty clays and clayey silts which are unlikely to be significant aquifers. ITE conducted pumping tests in September 2003 to investigate the link between the perched aquifer and the underlying Quaternary sediments. Pumping tests conducted on monitoring wells MW15 to MW17 show that MW17 could not support a pumping rate of 0.01 L/min and went dry, while MW15 and MW16 supported pumping rates of 0.8 L/min and 1.5 L/min, with 2.475 m and 1.209 m of drawdown respectively. Although ITE did not use the data for derivation of aquifer parameters, it can be inferred from the data that the sediments intercepted by these wells have low permeability.

The Devonian basement aquifer is reported by Leonard, (1994) as being massive with low primary porosity and permeability. Fractures are the main conduit for groundwater flow in these rocks. The degree of weathering also influences the movement of groundwater through this aquifer. The aquifer is likely to be recharged through the overlying Quaternary alluvial deposits.

3.3.4 Site Hydrogeology

Perched (in Fill)

Perched groundwater has been identified in the fill material outside of the backfilled excavation in the northern area of the site. Based on the most recent gauging event at the site, the depth to perched groundwater exists from 0.295 meters below top of casing (mBTOC) (MW20) to 1.163 mBTOC (MW40).

No comment can be made regarding groundwater flow direction within the perched aquifer (fill), as only two monitoring wells remain in the perched aquifer following decommissioning of the perched wells from the excavated area. There is no evidence from the logs of the regional groundwater monitoring wells drilled to the south and east of the site (MW18, MW19, MW26 to MW31) to suggest that the perched aquifer extends off-site to the south, southwest or southeast. Coffey did not intersect perched groundwater in MW28A and MW29A, located to the east of the site.

Previous investigations by ITE suggest that the groundwater in the fill is perched by an underlying silty clay layer which prevents connection between the perched and regional water systems (URS, October 2007). As only two wells remain in the perched system, this data is difficult to verify although the groundwater elevations in MW20 and MW21 are higher than the deeper regional wells. The TDS concentrations for the perched wells varied from 30 mg/L (MW40) to 1,963 mg/L (MW51) in the June 2011 sampling round, which are lower than the majority of the TDS concentrations measured in the regional wells located outside of the backfilled excavation.

Perched (in Backfilled Tank Pit Excavation)

When drilled in June 2003, most of the perched wells within the previously excavated areas, apart from MW38, were found to be dry. However, the water levels in these perched wells rose after June 2004, indicating the gradual influx of water into the previously excavated area. The relationship of the perched aquifer in the fill and the perched water in the previously backfilled excavation is unclear. In general, the water levels in the perched aquifer within fill material are higher than those in the previously backfilled excavation.

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Regional Aquifer

Based on the 2011 data (Coffey, 2011), the regional aquifer is located in a silty clay aquifer with standing water level (SWL) ranging between 0.270 mBTOC (MW29A) and 1.935 mBTOC (MW19). Groundwater elevation was reported to range between 51.380 mAHD at MW27 to 54.137 mAHD at MW55A.

The inferred groundwater flow direction in the regional aquifer has varied over the course of assessments at the site from south to southeast towards Caribbean Lake and Corhanwarrbul Creek. However, the inferred groundwater flow direction from the 2011 GME was reported to be to the southwest (Table 3.3, Coffey 2011). The Auditor has checked the groundwater elevations and inferred contours presented in Coffey (2011) and notes that the inferred groundwater flow direction during the June/July 2011 GME appears to be north-west.

Based on the groundwater elevations provided (Coffey, 2011), there was an increase (ranging from approximately 0.5 to 1.0m) in groundwater elevation between the 2010 GME and June/July 2011 GME in the following groundwater wells in particular: MW27, MW31, MW30A, MW55A, MW54A, MW29A and MW52A. These groundwater wells are predominantly located off-site (to the east and southeast of the site) in unsealed areas with a greater potential for infiltration from rain and surface water. According to the data provided, the groundwater elevation in on-site groundwater wells (in sealed areas) remained relatively stable (changes of less than 0.1m) between the 2010 GME and the June/July 2011 GME. The Auditor notes that the inferred regional flow direction in the wider area is expected to be towards the southeast. The inferred groundwater flow direction beneath the site in 2011 is not considered to alter the outcome of the Audit as the spatial distribution (as seen in Appendix I) of the residual contamination is consistent and delineates the extent of groundwater contamination off-site to the southeast.

No specific groundwater hydraulic conductivity or groundwater velocity assessments have been undertaken recently, however, the contamination contours (Appendix I) suggest that the hydrocarbon groundwater plume extends 10 to 15 m to the southeast into the Cathies Lane Reserve.

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4.0 Groundwater Quality Management Plan (GQMP)

4.1 Introduction

Following the completion of the s53V Audit Report (URS, October 2007), a GQMP (Coffey, 2008) was prepared, which incorporated the recommendations of the Audit report (URS, October 2007) with respect to ongoing groundwater monitoring (i.e. drilling additional monitoring wells, wells to be sampled, sampling method, analytical schedule, quality assurance/quality control (QA/QC) samples and sampling frequency).

The Auditor reviewed and commented on a draft GQMP and his comments were adequately incorporated into the final version (Coffey, 2008). This was documented in e-mail correspondence between the Auditor and Coffey relating to the GQMP (Coffey, 2008).

The final GQMP (Coffey, 2008) was reviewed and accepted by the Auditor and was implemented by Coffey in subsequent GMEs. In accepting the GQMP, the Auditor considers that the GQMP has been prepared in accordance with EPA guidelines (e.g. EPA Publication 840) and expectations.

It is noted that the CUTEP submission from the Auditor (URS, 2009) contained some requirements relating to groundwater management that were additional to those of the GQMP (e.g. monitoring for natural attenuation parameters in MW30 and MW31 - down gradient wells and re-installation of MW50 and MW52 to enable them to detect Phase Separated Hydrocarbons (PSH) if present). Our review of correspondence relating to the scopes of the GME’s and post Phase 2 ESA (as well as the GME reports) that occurred subsequent to the CUTEP submission (URS 2009), indicates that both the requirements of the GQMP and those of the Auditor CUTEP submission have been implemented during subsequent groundwater monitoring at the site.

4.2 Auditor Review of Groundwater Monitoring in accordance with the

GQMP

In June 2012, and at the request of EPA Victoria, the Auditor completed a review of the groundwater monitoring that has been undertaken to date in accordance with the abovementioned GQMP (AECOM, June 2012). The results of this review are provided in the Table 5 below. The Auditor notes that whilst the review was conducted for the purposes of comparing the groundwater monitoring works to the requirements of Sections 3.1 and 3.2 of the Draft PAN, the scope of review and outcomes are relevant to the objectives and scope of this Audit (see Table 2 Audit Objectives, Scope and Methodology).

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Table 5 Findings of the Auditor’s Review conducted in June 2012

Please note that the appendices referred to in this table are the appendices of the Auditor’s Review conducted in June 2012, not the appendices of this Audit Report.

No. Requirement of Draft PAN Scope of Works Undertaken by

AECOM Outcome of Review

3.1 Submit to EPA a Groundwater Quality Management Plan (GQMP) for identifying changes in groundwater quality (if any) immediately down gradient of the site, as well as the extent of the GQRUZ, to provide confirmation that beneficial uses are protected outside the contamination plume. The plan should include the completion of a s53V audit prior to the cessation of groundwater management and monitoring to confirm that no unacceptable risk remains

The following documents were reviewed:

GQMP (Coffey, 2008).

CUTEP submission (URS, 2009).

The Auditor considers that the GQMP (and GMEs undertaken in accordance with the GQMP), enables changes in groundwater quality (if any) immediately down gradient of the site to be identified.

The CUTEP nominates the extent of the GQRUZ and enables confirmation that beneficial uses are protected outside the contamination plume. The extent of the GQRUZ was based on groundwater modelling, incorporating conservative assumptions, and is located beyond the extent of the groundwater plume at the site.

Section 8.5 of the CUTEP submission (Cessation of Groundwater Management) includes the completion of a s53V Environmental Audit prior to the cessation of ongoing groundwater monitoring at the site.

3.2

3.2.1

The GQMP referred to in requirement 3.1 and must be verified by an EPA-appointed environmental auditor to ensure that:

Fulfils the environmental monitoring program addresses all of the risks posed by groundwater contamination from the premises and is in accordance with all applicable State Environment Protection Policies.

The following documents were reviewed: GQMP (Coffey, 2008).


Scope works documented from GMEs / Additional Investigations: Interim GME February 2010 (Coffey, 12 April 2010a), Post Phase 2 ESA August / September 2010 (Coffey, 30 November 2010b), Interim GME June / July 2011 (Coffey, 19 September 2011)

E-mail correspondence between Coffey, Auditor and Mobil relating to the GQMP (Coffey, 2008) and groundwater management

Based on the review undertaken in accordance with the scope of works, the Auditor confirms that the GQMP (Coffey, 2008) has been reviewed and endorsed by the Auditor and was implemented by Coffey (in subsequent GMEs).

The Auditor reviewed and commented on a draft GQMP and his comments were adequately incorporated into the final version (Coffey, 2008). This was documented in e-mail correspondence between the Auditor and Coffey relating to the GQMP (Coffey, 2008).

The CUTEP submission from the Auditor (URS, 2009) contained some requirements relating to groundwater management that were additional to those of the GQMP (e.g. monitoring for natural attenuation parameters in MW30 and MW31 - down gradient wells; re-installation of MW50 and MW52 to enable them to detect PSH (if present). Our review of correspondence relating to the scopes of the GME’s and post Phase 2

ESA (as well as the GME reports) that occurred subsequent to the CUTEP submission (URS 2009), indicates that both the requirements of the GQMP and those of the CUTEP submission have been implemented.

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requirements in the CUTEP submission (URS, 2009).

The Auditor concludes that based on the review undertaken, the methodology outlined in the GQMP and CUTEP submission has been followed during subsequent GMEs. This includes appropriate assessment and consideration of the protection of beneficial uses outlined in the SEPP.

Based on these findings, the Auditor considers that groundwater monitoring has been undertaken in accordance with that methodology and commitments outlined within the CUTEP and requirements of the SEPP.

No further action is recommended.

3.2.2 The GQMP confirms the stability and behaviour of the plume and sets triggers and contingencies for addressing any changes in conditions at the premises.

The following documents were reviewed: GQMP (Coffey, 2008).


Additional Response to EPA queries on CUTEP Submission (URS 25 October 2010).

Post Phase 2 ESA August / September 2010 (Coffey, 30 November 2010b).

Interim Groundwater Monitoring Event Report (June / July 2011), Coffey September 2011).

Contaminant Contours, Benzene, C6-C9, C10-C36, Perched and Regional Groundwater – 2004 to 2011 (Appendix C) and Historical Groundwater Monitoring Results, Perched and Regional Groundwater – 2003 to 2011 (Appendix D)

The Auditor considers the groundwater monitoring in accordance with the GQMP is sufficient to confirm the stability of and behaviour of the plume.

It is noted that sentinel groundwater monitoring wells MW54 and MW55 – which form part of the GQRUZ – were replaced with MW54A and MW55A. The original wells were destroyed by ‘others’ during road works on Ferntree Gully Road in 2010 and were replaced during the Post Phase 2

ESA (Coffey, 30 November 2010). The locations of the alternative wells were previously documented in the CUTEP submission as back up locations (in the case that the preferred locations could not be drilled).

It is also noted that a number of other groundwater wells were reinstalled during the Post Phase 2 ESA August / September 2010 works (Coffey, 30 November 2010b). These works were undertaken to replace monitoring wells considered to have been installed incorrectly or destroyed. This included monitoring wells MW50 and MW52, which have historically reported standing water levels up to 3m above the screened interval. The Auditor notes that an attempt was made to reinstall these wells (MW50A and MW52A – Coffey, 2010b) with the screen consistent with the standing water level measured in MW50 and MW52.

The GQMP (Coffey, 2008) incorporates ‘Trigger Levels/Points and

Contingency Plan’ (see Section 4.9 of the GQMP). These commitments are commensurate with Section 8.2 (Trigger Levels and Contingencies) of the CUTEP (URS, 2009). With the exception of replacing monitoring wells MW50 and MW52 as a contingency measure (as noted above), the Auditor is satisfied that the trigger levels have not been activated during the GQMP

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Based on the above review, an assessment was made on whether the degree and extent of the dissolved phase plume is stable / decreasing or increasing in the perched and regional aquifer system.

monitoring period (therefore the contingencies have not been necessary). The Auditor notes that increasing concentrations of dissolved hydrocarbons over three consecutive monitoring events has occurred in a few wells (eg. MW38, MW19A, MW19), these concentrations are within historically recorded ranges and are not considered to represent a change in contamination status.

Based upon a review of Contaminant Contour Plans (for Benzene, C6-C9, C10-C36, Perched and Regional Groundwater – 2004 to 2011: - Appendix C) and Historical Groundwater Monitoring Results (for Perched and Regional Groundwater – 2003 to 2011: - Appendix D) as prepared and updated by Coffey as part of this review, the following plume behavioural characteristics are noted:

Dissolved phase hydrocarbon contamination in the regional and perched aquifer, appears to be in a stabilised condition since remediation. The spatial extent and maximum concentrations of concern appear to be relatively consistent since 2004 to present and are noted to be concentrated in the southeast of the Site. This includes concentrations of benzene and TPH C6-C9 (>10,000ug/L) reported in the southeast at locations MW19A, MW26 and MW49).

Minor differences in the spatial distribution of dissolved hydrocarbons noted during each monitoring period may be attributed to installation of new monitoring wells to delineate the hydrocarbon plume (i.e.: regional wells MW19A, MW49, MW50 and MW52 installed between the June – August 2007 and August 2008 sampling rounds), change in standing water levels (i.e.: water present in wells during one sampling round and then dry during the next sampling round) and changes in contaminant concentrations.

Fluctuations in concentrations of dissolved hydrocarbons in some of the more impacted monitoring well locations is considered to be consistent with the presence of hydrocarbon at the water table and variations in groundwater elevation over time.

Based on the above findings, no further action is recommended.

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3.2.3 The GQMP outlines a process to determine any increase in plume extent and/or concentration levels which could constitute a risk to human health or the environment, including contingencies related to remediation activities, if necessary.




Interim Groundwater Monitoring Event Report (June / July 2011), Coffey September 2011).

The Auditor has reviewed the GQMP (Coffey, 2008) and CUTEP (URS, 2009) and notes the following procedures outlined within the plan to meet objective 3.2.3 of the draft PAN:

Monitoring – Undertake regular GMEs to determine any spatial increase of plume extent and/or concentrations levels by presenting comparison data (as shown in Appendix C and Appendix D).

Trigger Levels and Contingencies:

o The GQMP contains the following trigger: Changing of the

future land use to more sensitive than general non sensitive

commercial / industrial. A change in site use has not occurred (current site use is a service station) therefore change in potential risk has not occurred.

o The CUTEP submission (URS, 2009) contains the following trigger. Identification of a registered groundwater bore for a

beneficial use precluded by pollution within 300m down gradient

of the site boundary. No wells have been installed <less than 300m down gradient of the Site. A recent Victorian Groundwater Database search undertaken by Coffey (updated in 2011 GME report (Coffey, 2011) confirmed the nearest well reported was located 710m northeast of the Site (i.e. up gradient).

It is noted that the GQMP (Coffey, 2008) does not contain contingencies relating to remediation, however EPA’s periodic review

of the practicability to restore beneficial uses following a CUTEP determination is acknowledged.


3.2.4 The environmental monitoring program addresses all of the risks posed by groundwater contamination from the premises.


Environmental Audit Former Fuelzone, 1271 Ferntree Gully Road, Scoresby Victoria (URS,

The Environmental Audit Report (URS, October 2007) identified the following assessment of risk to groundwater:

Maintenance of Highly Modified Ecosystems – does not exist at the Site.

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October 2007).


Agriculture, Parks and Gardens –not currently or likely to be realised.

Stockwatering – precluded / does not exist or in the vicinity of the Site.

Industrial – currently does not exist at or surrounding the Site.

Primary Contact Recreation – precluded / does not exist at the Site.

Human health – risk to Site workers considered to be low and acceptable based on current land use scenario.

Based on the above assessment of risk, the GQMP (Coffey, 2008) addresses all of the relevant beneficial uses through the following mechanisms outlined within the plan:

Monitoring – numerous GMEs have been undertaken since 2004 to determine changes in plume characteristics.

Site Land Use – The GQMP (Coffey, 2008) states that a trigger is in place to monitor if there is a change in land use (to a more sensitive land use) and record an exceedance in line with the current risk profile.

Installation of wells less than 300m from the Site – Regular Victorian Groundwater Database searches have been undertaken by Coffey to ensure that this control is monitored (most recent search reported in 2011 GME report (Coffey, 2011)).


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After completing the review summarised in Table 4 above (see also AECOM, June 2012), the Auditor concluded that the GQMP (Coffey, 2008) has been implemented and that groundwater quality at and down hydraulic gradient of the site has remained relatively consistent throughout the monitoring period. The Auditor recommended this Audit be commenced to assess the risk posed by the residual contamination at and from the site and make formal recommendations relating to ongoing management of polluted groundwater (including monitoring) in accordance with EPA Publication 840. On 8 August 2012, EPA Victoria confirmed that on the basis of the June 2012 review, this Audit is the appropriate mechanism to confirm if groundwater monitoring can cease.

4.3 Adequacy of GQMP

The following text assesses the adequacy of the GQMP according to the methodology in Table 2 (Environmental Audit Objectives and Scope). As stated in Section 4.1, the final GQMP (Coffey, 2008) was reviewed and accepted by the Auditor and was implemented by Coffey in subsequent GMEs. In accepting the GQMP, the Auditor considers that the GQMP has been prepared in accordance with EPA guidelines (e.g. EPA Publication 840) and expectations.

4.3.1 Stability and behaviour of the plume

The Auditor considers that the groundwater monitoring in accordance with the GQMP is sufficient to confirm the stability of and behaviour of the plume for the following reasons:

- The groundwater well network monitored at the site includes groundwater wells within and around (including down hydraulic gradient) the plume. The monitoring record of some of these wells extends from to 2004 (i.e. long term monitoring record). The groundwater wells that define the extent of the GQRUZ to the southeast of the site are generally located between approximately 40 to 75 m down hydraulic gradient of the nearest contaminated groundwater well (See Coffey’s figure titled ‘Groundwater Quality Restricted Use Zone

(January 2009)’ No. ENVIABTF07066YA-D01A in Appendix A). As a result, monitoring these groundwater wells in accordance with the GQMP enables the Auditor to confirm whether or not the plume is remaining stable or otherwise;

- The monitoring well network has been monitored with a few exceptions. As detailed in Table 5, sentinel groundwater monitoring wells MW54 and MW55 (which form part of the GQRUZ) were replaced with MW54A and MW55A. These alternative groundwater well locations were previously documented in the CUTEP submission (in the event that the preferred locations could not be drilled); and

- Undertaking six monthly GMEs allows for assessment of plume stability and behaviour. The Auditor notes that the following GMEs have been undertaken in accordance with the monitoring frequency and analytes described within the GQMP: August 2008, February 2009, August 2009, February 2010, September 2010 and June/July 2011. Data from these GMEs was reported on and incorporated into the various responses to EPA queries relating to the CUTEP submission. The Auditor further notes that the most recent GME (June/July 2011) was conducted nine months after the previous GME, however, no significant change in groundwater concentrations or petroleum hydrocarbon distribution was observed. The relative consistency of groundwater concentrations and stability of the plume during the GQMP period (and since remediation in 2004) is discussed in Section 5, and presented in Appendices H, I and K.

4.3.2 Triggers and contingencies

The Auditor considers that the GQMP adequately stipulates triggers and contingencies for addressing any changes in conditions at the premises (as described below).

Section 4.9 of the GQMP (Coffey, 2008) incorporates ‘Trigger Levels/Points and Contingency Plan’. These

commitments are commensurate with Section 8.2 (Trigger Levels and Contingencies) of the Auditors CUTEP submission (URS, 2009) and are considered appropriate for addressing any change in conditions at the premises.

Further, with the exception of replacing monitoring wells MW50 and MW52 as a contingency measure to enable them to detect PSH if present and replacing MW54 and MW55 (as described above), the Auditor is satisfied that the trigger levels have not been activated during the GQMP monitoring period.

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The Auditor specifically notes the following:

- The GQMP contains the following trigger: “Changing of the future land use to more sensitive than general

non sensitive commercial / industrial”:

A change in site use has not occurred (i.e. current site use is a service station – commercial/industrial use) therefore potential risk has not changed; and

- The CUTEP submission (URS, 2009) contains the following trigger: “Identification of a registered

groundwater bore for a beneficial use precluded by pollution within 300 m down gradient of the site

boundary”:

No monitoring wells have been installed less than 300 m down gradient of the site. A Groundwater Database search undertaken by the Auditor (14 November 2012) confirms that the nearest groundwater monitoring well (Bore 82295) was located approximately 820 m northeast of the site (i.e. up hydraulic gradient). Please refer to Appendix J for a copy of the database search.

4.3.3 Process to determine an increase in plume extent and/or concentration levels

The Auditor considers that the GQMP has an adequate process to determine any increase in plume extent and/or concentration levels which could constitute a risk to human health or the environment for the following reason:

Undertaking six monthly GMEs allows for the determination of any spatial increase of plume extent and/or concentrations. The groundwater wells monitored in accordance with the GQMP are located within and at the periphery of the plume (including GQRUZ boundary), enabling changes in plume extent to be assessed. Please refer to Section 4.3.1 for further discussion regarding monitoring frequency.

4.3.4 Does the monitoring program address all of the risks posed by groundwater contamination

from the premises?

The Audit (URS, 2007) concluded that:

- Residual hydrocarbon contamination poses no unacceptable risk to on-site workers (commercial land use) and on-site intrusive workers; and

- Beneficial uses of groundwater precluded by the remaining pollution are neither existing nor likely at or in the vicinity of the site due to groundwater quality variability (background TDS), low aquifer yield (silty clays) and the inconsistency of these beneficial uses with the existing and likely long term use of the site and surrounding areas.

The final GQMP (Coffey, 2008) was reviewed and accepted by the Auditor and was implemented by Coffey in subsequent GMEs. In accepting the GQMP, the Auditor considers that the monitoring program addresses the risks posed by groundwater contamination from the premises.

The Auditor concludes that based on the review undertaken, the methodology outlined in the GQMP and CUTEP submission has been followed during subsequent GMEs. This includes appropriate assessment and consideration of the protection of beneficial uses outlined in the SEPP.

Based on this assessment, the GQMP is considered by the Auditor to be adequate.

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5.0 Groundwater Quality at the Site As detailed above, six GMEs have been undertaken in accordance with the GQMP. They are: August 2008; February 2009, August 2009; February 2010, September 2010; and June/July 2011 (note that these dates relate to when the groundwater sampling was undertaken and the GME reports are dated several months later).

5.1 Groundwater Monitoring Data

The Auditor has assessed the groundwater monitoring and analytical results with the GQMP. In doing so, the Auditor has referred to the following documents prepared and updated by Coffey:

- 2003 to 2011 Historical Groundwater Monitoring Results (Appendix H);

- 2004 to 2011 Contaminant Contour Plans for Benzene, C6-C9, C10-C36 (Appendix I);

- 2003 to 2011 Groundwater Charts – Groundwater Elevation and Hydrocarbon Concentrations (Appendix

K).

Based on the concentrations and distribution of analytes detailed in Appendices H, I and K, including the most recent GME (June/July 2011), the Auditor makes the following observations:

- Regional Aquifer

PSH has not been observed in any groundwater monitoring wells in the regional aquifer during the GQMP period.

Elevated concentrations of petroleum hydrocarbons have consistently been recorded across the site during the GQMP period. These concentrations are within the range of concentrations measured prior to the GQMP period for each groundwater monitoring well.

The spatial extent of the petroleum hydrocarbons in the regional aquifer appear to be consistent during the GQMP period (See Appendix I), with the highest concentrations consistently located in the southeast portion of the site as follows:

Concentrations of benzene at locations MW19A, MW26 and MW49 were reported as 13,900 µg/L, 10,800 µg/L and 12,900 µg/L respectively in the June/July 2011 GME;

Concentrations of TPH C6-C9 at MW19A, MW26 and MW49 were reported as 22,400 µg/L, 15,800 µg/L and 19,000 µg/L respectively in the June/July 2011 GME.

The highest concentration of benzene reported during the GQMP period was 28,200 µg/L in groundwater from MW49 in the southeast of the site during the February 2010 GME.

The highest concentration of TPH C6-C9 reported during the GQMP period was 79,000 µg/Lin groundwater from MW19 during the February 2009 GME.

Some of the concentrations of benzene reported in groundwater monitoring wells MW49 and MW39 during the GQMP period are indicative of the presence of residual PSH in the vicinity of these two groundwater wells.

The concentrations of dissolved hydrocarbons (TPH C6-C9) have increased over three consecutive monitoring rounds (i.e. February 2010, September 2010 and June 2011) in MW19A, MW19 with concentrations 17,300 µL, 17,400 µL, 22,400 µL respectively (for MW19A) and 25,600 µL, 26,000 µL, 34,800 µL respectively (for MW19) (See Appendix H).

These concentrations are within historically recorded ranges of these groundwater wells (i.e. TPH C6-C9: up to 60,400 µL in MW19A during August 2008; and up to 170,000 µL in MW19 during July 2003). As such, they are not considered to represent a change in contamination status.

Elevated concentrations of dissolved hydrocarbons have consistently been recorded at the site boundary or immediately off-site in Cathies Lane Reserve (i.e. MW19) during the GQMP period, however, they are reported to be below laboratory LOR at those groundwater wells which are located 15-20 m into the reserve (i.e. MW28/MW28A and MW29/MW29A).

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With the exception of benzene in groundwater from monitoring well MW31 on three occasions (2 ug/L in August 2008, 6 ug/L in February 2009 and 1 ug/L in February 2010), benzene concentrations were reported to be less than the laboratory LOR (1 ug/L) in groundwater monitoring wells MW30, MW30A and MW31. These three groundwater wells are located at and approximately 10-15 m to the southeast of the site boundary (see Appendix H). Benzene was reported to be less than the laboratory LOR in MW31 during the June/July 2011 GME and the concentrations of toluene, ethyl benzene and xylene were less than the laboratory LOR in these groundwater wells in all GMEs during the GQMP period.

Further, TPH (C10-C36) was detected at concentrations less than the adopted groundwater quality criteria in MW31 during the June/July 2011 GME. The concentration of TPH C10-C36 in MW31 was less than the laboratory LOR in the other GMEs during the GQMP period. The concentration of TPH C10-C36 was less than the laboratory LOR in MW30 and MW30A in all GMEs during the GQMP period.

TPH (C6-C9 and C10-C36) and BTEX were reported to be below the laboratory LOR in groundwater wells defining the off-site extent of the GQRUZ (MW18, MW28/MW28A, MW29/MW29A, MW54/MW54A, MW55/MW55A and MW56) during the GQMP period.

Overall, there has been no significant change in concentrations or distribution of petroleum hydrocarbons during the GQMP period (i.e. the highest concentrations of TPH and BTEX have remained in the southeast portion of the site and concentrations down hydraulic gradient remain mostly below the laboratory LOR (See Appendix I).

- Perched water:

PSH has not been observed in any groundwater monitoring well in the perched water during the GQMP period.

The spatial extent and maximum concentrations of petroleum hydrocarbons are relatively consistent during the GQMP period in the perched water zone (similar to the regional aquifer), with the highest concentrations consistently reported in the southeast portion of the site as follows:

Concentrations of benzene at locations MW38 and MW48 were reported as 17,500 µg/L and 5,520 µg/L respectively in the June/July 2011 GME.

Concentrations of TPH C6-C9 at locations MW38 and MW48 were reported as 22,400 µg/L and 7,100 µg/L respectively in the June/July 2011 GME.

The highest concentration of benzene reported during the GQMP period was 17,700 µg/L in groundwater from MW48 during the February 2010 GME.

The highest concentration of TPH C6-C9 reported during the GQMP period was 22,400 µg/L in groundwater from MW38 during the June/July 2011 GME.

The maximum dissolved benzene concentrations reported in perched water during the GQMP period do not appear to be indicative of the presence of residual PSH.

The concentrations of dissolved hydrocarbons have increased over three consecutive monitoring rounds (i.e. February 2010, September 2010 and June 2011) in MW38 with TPH C6-C9 concentrations of 10,200 µL, 18,300 µL, and 22,400 µL respectively; and benzene concentrations of 6,590 µL, 13,700 µL, and 17,500 µL respectively (See Appendix H).

These concentrations are within historically recorded ranges for this groundwater well during the GQMP period (i.e. TPH C6-C9: up to 63,000 µL during the January 2006 GME and benzene: up to 29,000 µL during the January 2006 GME). As such, they are not considered to represent a change in contamination status.

There has been no significant change in concentrations or distribution of contaminants in the perched water during the GQMP period (See Appendix I).

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5.2 Summary

Based on the concentrations and spatial distribution of the dissolved hydrocarbons in groundwater during the 2011 GME and the remainder of the GQMP monitoring period, the Auditor concludes the following:

- The concentrations of petroleum hydrocarbons in groundwater reported in the GQMP period are relatively consistent and are within the historically recorded range (i.e. there has been no significant change since the previous Audit);

- Dissolved phase hydrocarbon concentrations in the regional aquifer and perched water, appear to be in a stabilised condition. As discussed above, the spatial extent and maximum concentrations of petroleum hydrocarbons have remained relatively consistent during the GWMP period and since 2004, with the highest concentrations consistently in the southeast portion of the site. This includes concentrations of benzene and TPH C6-C9 (>10,000 µg/L) reported at locations MW19A, MW26, MW38 and MW49);

- Minor differences in the spatial distribution of dissolved hydrocarbons noted during each GME may be attributed to the following:

Installation of new monitoring wells to delineate the hydrocarbon plume (i.e. regional wells MW19A, MW49, MW50 and MW52 installed between the June and August 2007 and August 2008 sampling rounds);

Change in standing water levels (i.e. water present in groundwater wells during one sampling round and then dry/insufficient water during the next sampling round [e.g. MW20, MW51, MW18, MW19 and MW30]);

Changes in contaminant concentrations; and

Fluctuations in concentrations of dissolved hydrocarbons in some of the more impacted groundwater monitoring well locations is considered to be consistent with the presence of PSH at the water table, and variations in groundwater elevation over time.

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6.0 Assessment of Risk to Beneficial Uses of Land and Groundwater

6.1 Introduction

6.1.1 Previous Audit (URS, 2007)

An assessment of risk to beneficial uses of land and groundwater caused by residual soil and groundwater contamination at and from the site was undertaken in the previous Environmental Audit (URS, 2007).

The previous Audit (URS, 2007) concluded the following with respect to beneficial uses of groundwater:

- The beneficial use ‘maintenance of ecosystems” was found not to exist at the site. This beneficial use exists at the point of discharge of groundwater to the nearest surface water system, located approximately 1 km to the southeast and west of the site. The groundwater quality objectives for this beneficial use were observed to be exceeded at the site, however, groundwater monitoring data at the site combined with an estimated groundwater flow velocity indicated that ‘maintenance of ecosystems’ was unlikely to be affected by groundwater contamination at the site.

- The beneficial use ‘agriculture, parks and gardens’ was found not to be (or likely to be) realised at or around the site. Concentrations of BTEX compounds in groundwater at the site were expected to result in a ‘petrol’

odour that could result in groundwater not being used for this purpose (if it were to be realised). The potential use of groundwater for irrigation and watering use was determined to be limited by the background TDS concentrations (ranging from 620 mg/L, MW19 to 7,384 mg/L, MW27) which are suitable only for the irrigation of moderately salt tolerant crop species and has potential for deleterious effects on the soil (silty clay) structure.

- The beneficial use ‘stock watering” was found to be precluded by the benzene concentrations (>1 µg/L) in the perched aquifer around MW36, MW38, MW40 and MW46 as well as in the regional aquifer around MW19, MW26, MW33, MW35, MW39, MW41, MW43 and MW47. This beneficial use was found not to exist at the site and was considered not likely to be realised at, or in the vicinity of the site, as the zoning of the site and surrounding areas precludes the keeping of stock (intensive animal husbandry).

- The beneficial use ‘Industrial water use’ is restricted by the background TDS to “process wash waters” and

“once through cooling systems and make-up water”. Due to the presence of BTEX compounds in the groundwater that are likely to cause odours, this beneficial use was found to be precluded at the site. The use of groundwater for industrial water use was also found not to exist at the site or in the vicinity of the site and was considered to be unlikely due to low aquifer yield and variable groundwater quality.

- The beneficial use “primary contact recreation” for groundwater was considered to be precluded by the benzene and TPH C10-C36 concentrations in groundwater at the site. This beneficial use was found not to exist at or in the vicinity of the site at the time of Audit and was considered to be unlikely due to low aquifer yield and variable groundwater quality.

The previous Audit (URS, 2007) concluded the following with respect to beneficial uses of land:

- Residual soil contamination remaining beneath the site exceeds the adopted soil criteria for “maintenance of

ecosystems” for BTEX and TPH, however, under the commercial/industrial land use scenario with limited soil access there is minimal potential for exposure to the identified ecological receptors;

- The aesthetically impacted soil beneath the site was not considered to adversely affect the ongoing use of the site as a service station.

Human Health

- The residual concentrations of petroleum hydrocarbons (including benzene) in soil at various locations across the site exceeded the adopted guidelines for human health in the previous Audit (URS, 2007). A quantitative Human Health Risk Assessment (HRA) was undertaken to assess the risk posed to the health of site workers (e.g. console operators, and workers involved in excavation works) by residual hydrocarbons in soil and groundwater at and around the site.

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- The HRA assessed the risk to on-site workers on both the indoor and outdoor environment, from inhalation of hydrocarbon vapours resulting from soil and groundwater contamination. The calculation of (non-threshold carcinogenic) risk associated with the inhalation of benzene was found by Coffey to be below 1x10-5 incremental lifetime risk of cancer (Coffey, 2006). In addition, Coffey concluded that the calculated Hazard Index (HI) for risks associated with the inhalation of threshold contaminants of potential concern (CoPC) was below the acceptable limit of 1.

- A further assessment of risk to on-site intrusive workers from the inhalation of vapours and direct contact (eg. dermal contact and incidental ingestion) was also undertaken. The calculation of (non-threshold carcinogenic) risk associated with the exposure to benzene was found to be below 1 x 10-5 incremental lifetime risk of cancer. In addition, the calculated HI for risks associated with exposures to threshold CoPC was found to be below the acceptable limit of 1. The predicted concentration of volatile CoPC that may accumulate within excavations was identified to be lower than the occupational exposure inhalation standards (TWAs).

- As such, the HRA concluded that the contamination remaining at the site posed no unacceptable risk to:

Workers at the service station or other commercial land uses (assuming the site remains sealed); and

On-site intrusive workers (undertaking excavations in contact with contaminated soil and groundwater) at the site.

It is noted that the HRA relates to ongoing commercial/industrial use of the site.

6.1.2 Risk to Beneficial Uses of Land and Groundwater during the GQMP period

This Audit report relates to the risk posed to beneficial uses of land and groundwater by residual concentrations of petroleum hydrocarbons in groundwater monitored during implementation of the GQMP (2008 – 2011). Please refer to Sections 6.2 and 6.3.

This assessment has not directly considered the residual hydrocarbons in soil for the following reasons:

- the residual hydrocarbons in soil were assessed in the previous Audit Report (URS, 2007);

- there is no evidence of a recent source of hydrocarbon contamination to soil; and

- there has been no further assessment of soil or soil vapour during the GQMP period.

6.2 Land

6.2.1 SEPP (Prevention and Management of Contamination of Land)

The SEPP (2002) — Prevention and Management of Contamination Land provides the framework for the protection of land and associated beneficial uses throughout Victoria. The policy allows for a consistent approach to the prevention of contamination of land and clean-up of polluted land in Victoria, and sets environmental quality indicators and objectives for each beneficial use. The SEPP defines certain land use categories and associated beneficial uses of land to be protected.

Table 1 of the SEPP (2002) identifies the following beneficial uses of the land to be protected under the industrial/commercial land use category:

- Human health;

- Maintenance of highly modified ecosystems;

- Buildings and structures; and

- Aesthetics.

In accordance with the Audit scope (Table 2), the assessment of risk to beneficial uses of land in this Audit is restricted to human health. The risk to other beneficial uses of land is assumed to be consistent with the previous Audit (URS, 2007).

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6.2.2 Assessment of Risk to Human Health

In assessing the risk posed to human health resulting from petroleum hydrocarbons in groundwater measured during the GQMP period, the Auditor has considered the quantitative HRA undertaken as part of the previous Audit (URS, 2007). The HRA is described in detail in the previous Audit Report (URS, 2007) and summarised in Section 6.1.1 above. As described in Section 5 of this Audit report, the concentrations of petroleum hydrocarbons in groundwater measured during the GQMP period are relatively consistent and are within the historically recorded range. The Auditor considers that the outcomes of the quantitative HRA remain valid for the following reasons:

- The concentrations of petroleum hydrocarbons are similar to or less than those assessed in the previous HRA;

- The land use at the site (operating service station) and surrounding areas remains the same as assessed previously; and

- The exposure scenarios (on-site workers, console operators and workers in excavations in contaminated areas) are the same as those previously assessed.

As a result, the Auditor concludes that the contamination remaining at the site poses no unacceptable risk to:

- Workers at the service station or other commercial land uses (assuming the site remains sealed); and

- On-site intrusive workers (undertaking excavations in contact with contaminated soil and groundwater) at the site.

It is noted that the HRA relates to ongoing commercial/industrial use of the site. It did not assess other land uses such as residential. Should the use of the site change in future, an assessment of the risk specific to the proposed use is recommended.

6.3 Groundwater

6.3.1 Perched water

Perched water has been identified in fill in the north of the site as well as in the backfilled excavation (following site remediation). Based on the background ‘post-purge’ groundwater TDS (30 mg/L to 1,963 mg/L) measured during the June/July 2011 GME and reported in Table 5.3 of Coffey (2011), the perched groundwater at the site falls mostly within Segment B in accordance with Table 1 of the State Environment Protection Policy

(Groundwaters of Victoria). To be consistent with the 2007 Audit, perched water at the site is classified as Segment A2 . Perched groundwater has not been observed in the regional wells drilled off-site to the south and southeast of the excavation area. Therefore, and as concluded within the Audit Report (2007), the beneficial uses associated with perched water are unlikely to be realised.

6.3.2 Regional Aquifer

The TDS of the regional groundwater, as measured during the June/July 2011 GME and reported in Table 5.3, Coffey (2011) ranges from 443 mg/L to 13,455 mg/L. Even though a number of regional monitoring wells have TDS values within the Segment C range, the aquifer is conservatively characterised as Segment B. Additionally, the Department of Sustainability and Environment (DSE) Victorian Groundwater Beneficial Use Map Series (South Western Victoria Water-table Aquifer Map) places the groundwater in the Scoresby area within Segment B. The beneficial uses protected within Segment B are listed in Table 6.

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Table 6 Beneficial Uses of Groundwater protected in Segment B

Beneficial Uses B

(1,000-3,501 mg/L TDS)

Maintenance of Ecosystems

Potable mineral water

Agriculture, parks and gardens

Stock watering

Industrial water use

Primary contact recreation (e.g. bathing, swimming)

Buildings and structures

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.

The groundwater CoPC at this site are not likely to be harmful to the buildings and structures and therefore this beneficial use is not discussed further.

6.3.3 Assessment of Risk to Beneficial Uses of Groundwater

Maintenance of Highly Modified Ecosystems

The beneficial use ‘maintenance of ecosystems” does not exist at the site. This beneficial use exists at the point of discharge of the groundwater to the nearest surface water system, such as Caribbean Lake (Corhanwarrabul Creek) and Dandenong Creek, located 1 km to the southeast and west of the site respectively.

The groundwater objectives for this beneficial use remained exceeded at the site during the GQMP period, however, based on the groundwater monitoring data around the site (which effectively delineates the plume) and the groundwater flow velocity estimated at the time of the 2007 Audit (1 to 20 m/yr), the beneficial use ‘maintenance of ecosystems’ is unlikely to be affected by groundwater contamination at the site.

This conclusion is consistent with the assessment of risk to this beneficial use in the 2007 Audit.

Agriculture, Parks and Gardens

Although there are no groundwater quality objectives for petroleum hydrocarbons for this beneficial use, the concentrations of BTEX compounds in groundwater at the site monitored during the GQMP period are expected to result in a ‘petrol’ odour that could result in groundwater not being used for this purpose (if it were to be realised). As a result, this beneficial use is considered to be precluded by the petroleum hydrocarbon contamination in groundwater at the site.

The potential use of groundwater for irrigation and watering use is limited by the background TDS concentrations ranging from 520 mg/L (MW41) to 10,400 mg/L (MW27) (Coffey, 2011). These TDS concentrations are suitable only for the irrigation of moderately salt tolerant crop species and has potential for deleterious effects on the soil (silty clay) structure. This conclusion is consistent with the assessment of risk to this beneficial use in the 2007 Audit.

The beneficial use ’agriculture, parks and gardens’ is not currently realised and is not likely to be realised at or in

the vicinity of the site due to variable quality and low aquifer yield.

Stock Watering

The groundwater quality objectives for this beneficial use remained exceeded at the site during the GQMP period. The concentration of benzene exceeds the objective (1 ug/L) at MW36, MW38, MW40, MW46 and MW48 (perched water) and MW16, MW19, MW19A, MW26, MW33, MW35, MW39, MW41, MW47 and MW49 in the regional aquifer, during the June/July 2011 GME. As a result, this beneficial use is considered to be precluded by the petroleum hydrocarbon contamination in groundwater at the site. This conclusion is consistent with the assessment of risk to this beneficial use in the 2007 Audit.

This beneficial use is not likely to be realised at, or in the vicinity of the site, as the zoning of the site and surrounding areas precludes the keeping of stock (intensive animal husbandry).

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Industrial Water Use

The beneficial use ‘Industrial water use’ is restricted by the background TDS to “process wash waters” and “once

through cooling systems and make-up water”. Due to the presence of BTEX compounds in the groundwater that are likely to cause odours, this beneficial use is considered to be precluded at the site. This conclusion is consistent with the assessment of risk to this beneficial use in the 2007 Audit.

The use of groundwater for industrial water use is neither existing nor likely to be realised at or in the vicinity of the site due to low aquifer yield and variable groundwater quality.

Primary Contact Recreation

The groundwater objectives for this beneficial use remained exceeded during the GQMP period. As a result, this beneficial use is considered to be precluded by the benzene and TPH C10-C36 concentrations in groundwater at the site. This conclusion is consistent with the assessment of risk to this beneficial use in the 2007 Audit.

This beneficial use does not exist at or in the vicinity of the site and is unlikely due to low aquifer yield and variable groundwater quality.

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7.0 Conclusions and Recommendations

7.1 Conclusions

Having reviewed the relevant data and reports and made an assessment of risk to the groundwater and land environments caused by groundwater contamination emanating from the site, the following is concluded.

- Following a recommendation in a previous Audit report (URS, 2007) and a CUTEP submission to EPA, a GQMP was prepared for the Former Scoresby Fuelzone site in 2008.

- The final GQMP (Coffey, 2008) was reviewed and accepted by the Auditor and was implemented in subsequent GMEs.

- In accepting the GQMP, the Auditor considers that:

The GQMP has been prepared in accordance with EPA guidelines (e.g. EPA Publication 840) and expectations;

The GQMP adequately stipulates triggers and contingencies for addressing any changes in conditions at the premises;

Groundwater monitoring in accordance with the GQMP is sufficient to confirm the stability and behaviour of the plume; and

The GQMP has an adequate process to determine any increase in plume extent and/or concentration levels which could constitute a risk to human health or the environment.

- Overall, the Auditor considers the GQMP to be adequate.

- The Auditor is satisfied that groundwater monitoring undertaken between August 2008 and June/July 2011 has been conducted in accordance with the methodology outlined in the GQMP. This has included:

Gauging and sampling groundwater monitoring wells nominated in the GQMP for specific analytes (mostly on a six monthly basis);

Maintaining the groundwater monitoring well network;

Replacing groundwater monitoring wells where necessary; and

Appropriate assessment and consideration of the protection of beneficial uses outlined in the SEPP.

- The following conclusions are made with respect to groundwater quality at the site:

PSH has not been observed in any monitoring well in the regional aquifer or perched water during the GQMP period.

Elevated concentrations of petroleum hydrocarbons in groundwater have been recorded across the site during the GQMP period. These concentrations are within the range of concentrations measured prior to the GQMP period for each monitoring well;

The spatial extent of the petroleum hydrocarbons in the regional aquifer has remained consistent during the GQMP period, with the highest concentrations consistently located in the southeast portion of the site;

Some of the concentrations of benzene reported in several regional groundwater monitoring wells in the southeast of the site during the GQMP period are indicative of the presence of residual PSH in the vicinity of these wells;

TPH (C6-C9 and C10-C36) and BTEX were reported to be below the laboratory LOR in groundwater wells defining the off-site extent of the GQRUZ (MW18, MW28/MW28A, MW29/MW29A, MW54/MW54A, MW55/MW55A and MW56) during the GQMP period; and

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Overall, there has been no significant change in concentrations or distribution of petroleum hydrocarbons during the GQMP period (i.e. the highest concentrations of TPH and BTEX have remained in the southeast portion of the site and concentrations down hydraulic gradient remain mostly below laboratory LOR). The concentrations of petroleum hydrocarbons in groundwater measured during the GQMP period are similar or less than those measured prior to the GQMP period (since remediation).

- The Auditor has undertaken an assessment of risk to the beneficial uses of groundwater at the site, and concluded that the following beneficial uses of groundwater are precluded by the petroleum hydrocarbons in groundwater at the site:

Agricultural, parks and gardens;

Stock Watering;

Industrial Water Use; and

Primary Contact Recreation.

- The precluded beneficial uses are the same as those identified in the previous Audit (URS, 2007), although it is noted that the beneficial uses may not apply to groundwater when a GQRUZ has been declared by EPA.

- The Auditor has considered the quantitative HRA undertaken as part of the previous Audit (URS, 2007) during the assessment of risk to the beneficial use human health. The Auditor has concluded that the outcomes of the quantitative HRA remain valid for the following reasons:

The concentrations of petroleum hydrocarbons in groundwater at the site are similar to or less than those assessed in the previous HRA;

The land use at the site (operating service station) and surrounding areas remains the same as assessed previously; and

The exposure scenarios (on-site workers, console operators and workers in excavations in contaminated areas) are the same as those previously assessed.

- As a result, the Auditor concludes that the concentrations of petroleum hydrocarbons in groundwater remaining at the site poses no unacceptable risk to:

Workers at the service station or other commercial land uses (assuming the site remains sealed); and

On-site intrusive workers (undertaking excavations in contact with contaminated soil and groundwater) at the site.

- It is noted that the HRA relates to ongoing commercial/industrial use of the site. It did not assess other land uses such as residential. Should the use of the site change in future, an assessment of the risk specific to the proposed use is recommended.

- Based on the overall assessment of the implementation of the GQMP, the recorded concentrations and distribution of petroleum hydrocarbons remaining in groundwater at the site, and the risk posed to the beneficial uses of land and groundwater assessed, the Auditor considers that ongoing groundwater monitoring at the site is not necessary. Therefore, ongoing groundwater monitoring in accordance with the GQMP can cease.

- The following ongoing management of the remaining groundwater contamination is required in accordance with EPA publication 840:

Regular information provision to those potentially affected (eg. intrusive workers at and adjacent to the site);

Controls on the use of polluted groundwater (i.e maintain the GQRUZ);

Triggers/contingencies relating to change in land use; and

Triggers/contingencies relating to the identification of groundwater use less than 300 m from the site.

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8.0 References AECOM (26 June 2012 Auditor Review of Former Mobil Scoresby Fuelzone Groundwater Monitoring Requirements.

Australian and New Zealand Environment and Conservation Council and the National Health and Medical Research Council (1992) Guidelines for Assessment and Management of Contaminated Sites.

Australian and New Zealand Environment and Conservation Council (1992b) Australian Water Quality Guidelines for Fresh and Marine Waters.

Australian and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand (2000) National Water Quality Management Strategy - Australian and New Zealand Guidelines for Fresh and Marine Water Quality.

Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (September 2011) Health Screening Levels for Petroleum Hydrocarbons in Soil and Groundwater.

Coffey Environments (October 2008) Groundwater Quality Management Plan, Former Mobil Service Station, Scoresby.

Coffey Environments (October 2008) Interim Groundwater Monitoring Event Report.

Coffey Environments (March 2009) Interim Groundwater Monitoring Event Report.

Coffey Environments (October 2009) Interim Groundwater Monitoring Event Report.

Coffey Environments (April 2010) Interim Groundwater Monitoring Event Report.

Coffey Environments (September 2010) Interim Groundwater Monitoring Event Report.

Coffey Environments (30 November 2010) Post Phase 2 Environmental Site Assessment August/September 2010.

Coffey Environments (September 2011) Interim Groundwater Monitoring Event Report.

Environment Protection Act 1970.

Environment Protection Authority of Victoria (April 2000) Publication 669 – Groundwater Sampling Guidelines.

Environment Protection Authority of Victoria (June 2002) Publication 854 - Policy Impact Assessment – Prevention and Management of Contamination of Land in Victoria.

Environment Protection Authority of Victoria (April 2003) Publication 902 Environmental Auditing in Victoria.

Environment Protection Authority of Victoria (September 2006) Publication 668 - Hydrogeological assessment (Groundwater Quality) Guidelines.

Environment Protection Authority of Victoria (August 2007) Publication 952.2 - Environmental Auditor Guidelines for the Preparation of Environmental Audit Reports on Risk to the Environment.

Environment Protection Authority of Victoria (August 2007) Publication 860.1 - Environmental Auditing of Contaminated Land.

Environment Protection Authority of Victoria (August 2007) Publication 953.2 - Environmental Auditor Guidelines for Conducting Environmental Audits.

Environment Protection Authority of Victoria (October 2008) Publication 865.7 - Environmental Auditor Guidelines for Appointment and Conduct.

Environment Protection Authority of Victoria (June 2009) Industrial Waste Resource Guideline 701 – Sampling and Analysis of Waters, Waste Waters, Soils and Wastes.

Minister for Planning (27 September 2001) Direction No. 1 - Planning and Environment Act 1987 Section 12 (2) (a) of the - Potentially Contaminated Land.

National Environment Protection Council (1999) National Environment Protection (Assessment of Site Contamination) Measure.

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National Environmental Health Forum (1996) Monographs Soil Series No. 1 - Health Based Soil Investigation Levels.

National Health and Medical Research Council and the National Resource Management Ministerial Council (2011) National Water Quality Management Strategy - Australian Drinking Water Guidelines 6 – 2011.

URS Corporation Australia (October 2007) Environmental Audit Former Scoresby Fuelzone, 1271 Ferntree Gully

Road, Scoresby Victoria.

URS Corporation Australia (January 2009), CUTEP Submission: Former Scoresby Fuelzone (VL3692), 1271

Ferntree Gully Road, Scoresby Victoria.

Victorian Government (June 2003) Variation to State Environment Protection Policy - Waters of Victoria.

Victorian Government (December 1997) State Environment Protection Policy - Groundwaters of Victoria.

Victorian Government (June 2002) State Environment Protection Policy - Prevention and Management of Contamination of Land.

Victorian Government (August 2004) State Environment Protection Policy - Waters of Victoria.

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9.0 Limitations This audit report has been prepared for Mobil Oil Australia Pty Ltd (Mobil) in accordance with Section 53V of the Environment Protection Act 1970. It has also been prepared consistent with the scope of work and for the purpose outlined in the Proposal dated 12 July 2012. The Audit Report represents the Auditor’s assessment of

the risk of any possible harm to beneficial uses of land and/or groundwater caused by residual hydrocarbon contamination at the 1271 Ferntree Gully Road, Scoresby (the site) at the date the Report is signed.

Mobil and EPA Victoria may use this Audit Report in reaching their conclusions about the site. The scope of work performed as part of the audit process 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 opinions stated in this report, the Auditor has relied on information described in assessment reports supplied by Mobil, Coffey, and URS (identified in section 2.2 of this Audit report) and a site inspections conducted by the Auditor and his representative. The Auditor has taken this information to represent a fair and reasonable characterisation of the site, within the limitations of the investigation as state herein. No indications were found during our investigations that information contained in the reports was false. No investigation can in practice be through enough to preclude the presence of materials on the site that presently, or in the future, may be considered hazardous.

The Audit and this report are limited by and rely upon the review’s scope, the information provided by Mobil and its consultants (Coffey and URS) through the documents provided to the Auditor. The Auditor used reasonable care to avoid reliance upon data and information that may be inaccurate. The Auditor’s conclusions presented in

this report are therefore based on the information made available to him and on his own observations during the Audit. Opinions and judgments expressed herein, which are based on the Auditor’s understanding and

interpretation of current regulatory standards, should not be construed as legal opinions.

The Auditor notes that subsurface conditions can vary over short distances. The actual characteristics of sub-surface and surface materials may vary significantly between adjacent sampling locations and intervals. Due to often-changing regulatory evaluation criteria, concentrations of potential contaminants present and considered acceptable may, in the future, become subject to different regulatory standards.

This report was prepared in November 2011 and is based on the conditions encountered and information reviewed at the time of preparation. AECOM disclaims responsibility for any changes that may have occurred after this time.

This report should be read in full. No responsibility is accepted for use of any part of this report in any other context or for any purpose or by third parties. This report does not purport to give legal advice. Legal advice can only be given by qualified legal practitioners.

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Plates

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Plate 1 – Paved site surface

Plate 2 – Canopy over the top of eight dispensing bowsers

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Plate 3 – Cathies Lane Reserve (facing south)