INFORMATION REGARDING ENVIRONMENTAL AUDIT REPORTS
August 2007
VICTORIA’S AUDIT SYSTEM AUDIT REPORT CURRENCY An environmental audit system has operated in Audit reports are based on the conditions encountered Victoria since 1989. The Environment Protection Act and information reviewed at the time of preparation 1970 (the Act) provides for the appointment by the and do not represent any changes that may have Environment Protection Authority (EPA Victoria) of occurred since the date of completion. As it is not environmental auditors and the conduct of possible for an audit to present all data that could be independent, high quality and rigorous environmental of interest to all readers, consideration should be audits. made to any appendices or referenced documentation An environmental audit is an assessment of the for further information. condition of the environment, or the nature and extent When information regarding the condition of a site of harm (or risk of harm) posed by an industrial changes from that at the time an audit report is process or activity, waste, substance or noise. issued, or where an administrative or computation Environmental audit reports are prepared by EPA- error is identified, environmental audit reports, appointed environmental auditors who are highly certificates and statements may be withdrawn or qualified and skilled individuals. amended by an environmental auditor. Users are Under the Act, the function of an environmental advised to check EPA’s website to ensure the currency auditor is to conduct environmental audits and of the audit document. prepare environmental audit reports. Where an environmental audit is conducted to determine the PDF SEARCHABILITY AND PRINTING condition of a site or its suitability for certain uses, an environmental auditor may issue either a certificate or EPA Victoria can only certify the accuracy and statement of environmental audit. correctness of the audit report and appendices as presented in the hardcopy format. EPA is not A certificate indicates that the auditor is of the opinion responsible for any issues that arise due to problems that the site is suitable for any beneficial use defined with PDF files or printing. in the Act, whilst a statement indicates that there is some restriction on the use of the site. Except where PDF normal format is specified, PDF files are scanned and optical character recognised by Any individual or organisation may engage appointed machine only. Accordingly, while the images are environmental auditors, who generally operate within consistent with the scanned original, the searchable the environmental consulting sector, to undertake hidden text may contain uncorrected recognition environmental audits. The EPA administers the errors that can reduce search reliability. Therefore, environmental audit system and ensures its ongoing keyword searches undertaken within the document integrity by assessing auditor applications and may not retrieve all references to the queried text. ensuring audits are independent and conducted with regard to guidelines issued by EPA. This PDF has been created using the Adobe-approved method for generating Print Optimised Output. To assure proper results, proofs must be printed, rather AUDIT FILES STRUCTURE than viewed on the screen. Environmental audit reports are stored digitally by This PDF is compatible with Adobe Acrobat Reader EPA in three parts: the audit report (part A), report Version 4.0 or any later version which is downloadable appendices (part B) and, where applicable, the free from Adobe’s Website, www.adobe.com. certificate or statement of environmental audit and an executive summary (part C). A report may be in colour FURTHER INFORMATION and black-and-white formats. Generally, only black- and-white documents are text searchable. For more information on Victoria’s environmental Report executive summaries, findings and audit system, visit EPA’s website or contact EPA’s recommendations should be read and relied upon only Environmental Audit Unit. in the context of the document as a whole, including Web: www.epa.vic.gov.au/envaudit any appendices and, where applicable, any certificate Email: [email protected] or statement of environmental audit.
1 of 145 REPORT ENVIRONMENTAL AUDIT AREA A - WEST MELBOURNE GASWORKS SITE
for Docklands Authority
Ref: CH\S:\Projects\37858\005\Audit rep A\GasworksAuditRepRevO.doc February 2002 2 of 145 m DAMES & MOORE PT~LTD A DAMES & MOORE COMPANY URS House 658 Church Street Richmond, Vic 3121 61-3-9279 2888 Tel 61-3-9279 2850 Fax
28 February 2002 Ref: CH\\\MELl\PROJECTS~ojectsU7858\005\Auditrep A\GasworksAuditRepRevO.doc
Docklands Authority AFL House, 140 Harbour Esplanade DOCKLANDS, VICTORIA 3008
Attention: Tom Graze
Dear Tom
ENVIRONMENTAL AUDIT REPORT AREA A - WEST MELBOURNE GASWORKS SITE
As discussed with Glenn Dixon, please find attached our report on the Environmental Audit of Area A of the former West Melbourne Gasworks site prepared in accordance with Section 53W of the Environment Protection Act 1970. In accordance with Section 12.6 of the Environmental Auditor Guidelines, a copy of this report is also provided directly to the EPA of Victoria, and a second copy on CD to the Docklands Authority as the representative Local Government Authority for its records.
We trust this meets with your requirements. However, if you have any queries or comments, please do not hesitate to contact us on 9279 2888.
Yours faithfully
Ken Mival Environmental Auditor (Contaminated Land)
DAMES & MOORE PTY LTD ACN 003 293 696 Offices Worldwide 3 of 145 “Though manufactured gas plant facilities have long ago been decommissioned, the sites upon which they stood serve today as a constructive focal point of dialogue between industry and the regulatory community regarding site characterisation, the assessment of risk, and the implementation of management alternatives that effectively protect public health and contribute positively to community development”
“Management of Manufactured Gas Plant Sites: The Gas Research Institute’s Two Volume Practical Reference Guide” Thomas D. Hayes et al. 1996, Amherst Scientific Publishers, Massachusetts.
4 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks Site February 2002 for Docklands Authority Page i
TABLE OF CONTENTS Page No.
1. INTRODUCTION ...... 12
1.1 PURPOSE OF REPORT ...... 14 1.2 PARTIES INVOLVED ...... 14 2. AUDIT GUIDELINES ...... 15
3. SCOPE OF AUDIT ...... 18
4. DOCUMENTS REVIEWED ...... 19
5. SITE DESCRIPTION ...... 22
5.1 SITE LOCATION & DESCRIPTION...... 22 5.2 ON-SITE ACTIVITIES AND USES...... 23 5.3 NEIGHBOURING LAND USES ...... 23 5.4 GEOLOGY & HYDROGEOLOGY ...... 24 5.4.1 Geology...... 24 5.4.2 Hydrogeology ...... 25 5.5 SITE CHARACTERISTICS...... 32 5.5.1 Topography & Drainage ...... 32 5.5.2 Natural Watercourses...... 32 5.5.3 Vegetation...... 32 5.5.4 Buildings...... 32 5.5.5 Underground Structures ...... 32 5.6 SITE HISTORY ...... 33 5.7 PREVIOUS INDUSTRIAL PROCESSES UNDERTAKEN ON-SITE ...... 34 5.8 BY-PRODUCTS AND WASTES GENERATED...... 35 5.8.1 Gas Production and Heat Recovery; & Tar/Oil/Water Separation...... 36 5.8.2 Gas Clean-Up...... 37 5.8.3 Wastewater Treatment ...... 38 5.8.4 Tar/Hydrocarbon Processing...... 38 5.9 MONITORIING OF SITE CONDITIONS ...... 39 6. BENEFICIAL USES OF THE SITE ...... 40
6.1 ASSESSMENT OF BENEFICIAL USES ...... 40 6.2 PREVIOUS BENEFICIAL USES...... 40 6.3 PROPOSED OR POSSIBLE BENEFICIAL USES ...... 41 6.4 RELEVANT ELEMENTS...... 41 7. POSSIBLE SOURCES OF CONTAMINATION...... 42
7.1 ON-SITE SOURCES ...... 42 7.2 OFF-SITE SOURCES ...... 42 7.3 CONTAMINANTS OF CONCERN...... 43 8. ASSESSMENT GUIDELINES...... 45
8.1 PURPOSE OF GUIDELINES USED FOR ASSESSMENT ...... 45 8.2 ANZECC ASSESSMENT GUIDELINES ...... 45 8.3 NEPM HEALTH INVESTIGATION GUIDELINES...... 46 8.4 NEPM ECOLOGICAL INVESTIGATION GUIDELINES ...... 47 8.5 STATUS OF GROUNDWATER IN AN AUDIT...... 47 8.6 GROUNDWATER POLICY AND GUIDELINES ...... 47 8.7 SITE SPECIFIC CLEAN UP CRITERIA ...... 48 9. REVIEW OF PREVIOUS ASSESSMENTS...... 50
9.1 INTRODUCTION...... 50 9.2 SUMMARY OF PREVIOUS ASSESSMENTS ...... 50
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TABLE OF CONTENTS (cont’d)
9.2.1 Environmental Audit Report (1993) ...... 50 9.2.2 Soil and Groundwater Contamination Assessment (1997) ...... 51 9.2.3 Groundwater Investigations (Egis 1999)...... 52 9.2.4 Proposed Encapsulation of Charles Grimes Bridge Road (Coffey, 1999) ...... 52 9.3 COMTECHPORT FILL...... 56 10. DERIVATION OF SITE SPECIFIC CLEAN-UP CRITERIA...... 57
10.1 SOIL QUALITY ACCEPTANCE CRITERIA...... 57 10.2 EGIS GROUNDWATER ASSESSMENTS...... 61 11. SITE REMEDIATION UNDERTAKEN ...... 63
11.1 MONITORING OF REMEDIATION OF AREA A UNDERTAKEN BY ENTERRA JV...... 63 11.1.1 Site Meetings ...... 63 11.1.2 Monitoring of Site Progress ...... 64 11.1.3 Material Tracking...... 64 11.2 IMPORTED FILL MATERIAL...... 69 11.2.1 Imported Natural Soils...... 70 11.2.2 Comtechport Fill ...... 71 11.3 CONSTRUCTION OF CLAY BUNDS...... 72 11.4 SOIL REMEDIATION PROCESSES ...... 73 11.4.1 Quicklime Treatment Process ...... 73 11.4.2 Potassium Permanganate...... 74 11.4.3 Fenton’s Reagent ...... 74 11.5 IDENTIFICATION AND CLASSIFICATION OF SOILS RE-USED ON AREA A ...... 75 11.6 OFF SITE DISPOSAL OF CONTAMINATED SOILS ...... 75 11.7 ACID SULPHATE SOILS ...... 76 11.8 RISK ASSESSMENTS...... 77 11.8.1 IT Environmental (2001) ...... 77 11.8.2 Auditor’s Risk Assessment (2001)...... 80 11.9 FATE & TRANSPORT MODELS ...... 80 11.9.1 IT Environmental (2001) ...... 80 11.9.2 Fate and Transport Model Undertaken by the Auditor (2001)...... 82 12. REVIEW OF REMEDIATION/VALIDATION DATA...... 84
12.1 OVERVIEW ...... 84 12.2 LABORATORIES USED BY THE SITE ASSESSOR...... 84 12.3 ANALYTICAL METHODS ...... 85 12.4 ANALYTICAL DATA VALIDATION ...... 86 12.5 QUALITY OF INFORMATION SUPPLIED ...... 87 12.5.1 General...... 87 12.5.2 RPD analysis - Soil ...... 90 12.5.3 RPD analysis - Groundwater...... 90 12.5.4 Surface Revalidation...... 91 12.6 UST VALIDATION ...... 92 12.7 ASBESTOS ...... 92 13. ASSESSMENT OF REMAINING HEALTH AND ECOLOGICAL RISKS ...... 93
13.1 POINT CONCENTRATIONS ...... 93 13.2 IMMINENT ENVIRONMENTAL HAZARDS ...... 95 13.3 HUMAN HEALTH RISKS ...... 95 13.4 ENVIRONMENTAL RISKS...... 97 13.4.1 Potential Pathways for Migration of Contaminants ...... 97 13.4.2 Discussion of Ecological Risks...... 97 13.5 GROUNDWATER RISKS ...... 98 13.5.1 Fill Material (A Wells)...... 104 13.5.2 Coode Island Silt/Fishermens Bend Silt (B Wells)...... 105
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TABLE OF CONTENTS (cont’d)
13.5.3 Moray Street Gravels (C Wells)...... 106 13.6 GROUNDWATER QUALITY IN AREA A ...... 106 13.6.1 Ammonia...... 106 13.6.2 Maintenance of Ecosystems – Existing and Likely...... 107 13.6.3 Primary Contact Recreation ...... 111 13.6.4 Buildings and Structures ...... 112 13.6.5 Industrial Water Use ...... 112 13.6.6 Potential for Recontamination of Shallow Groundwater ...... 113 13.6.7 Non Aqueous Phase Liquids ...... 113 13.7 GROUNDWATER AND SURFACE WATER QUALITY SUMMARY ...... 114 13.8 SOIL AESTHETICS ...... 115 14. ENVIRONMENTAL MANAGEMENT STRATEGY ...... 116
14.1 OBJECTIVES ...... 116 14.2 SCOPE ...... 117 14.2.1 Future Excavation Works...... 117 14.2.2 Groundwater Monitoring ...... 117 14.2.3 Groundwater Contingency Plan ...... 117 15. CONCLUSIONS...... 118
15.1 FINDINGS OF AUDIT...... 118 15.2 STATEMENT OF ENVIRONMENTAL AUDIT ...... 118 16. USE OF AUDITOR’S SUPPORT TEAM ...... 122
17. LIMITATIONS...... 123
18. REFERENCES ...... 124
TABLES
Table 13.4 Summary of Point Concentrations Remaining in Soils on Area A Table 13.5 Summary of Concentrations of Chemicals Recorded from Groundwater Bores Relevant to Area A
LIST OF FIGURES
Figure 1 Locality Map of Former West Melbourne Gasworks Site Figure 2 Site Plan showing boundaries of Audit Area (Area A) and location of historical activities Figure 3 Borehole Location Plan Figure 4 Adopted Groundwater Contours - 1997/98 Data Figure 5 Conceptual Geological Model of West Melbourne Gasworks Site
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TABLE OF CONTENTS (cont’d)
LIST OF APPENDICES
A Site Plan Supplied by Docklands Authority Defining Boundaries of The Site (GHD) B EPA Clean up Notice and Conditions & Letter on Clean-up to Extent Practicable C Summary Plan of Relevant Certificates of Title – Area A D Remediation Criteria as Agreed by Auditor for Inclusion in Remediation Contract E Example of RAP Including Remediation of Area A of West Melbourne Gasworks Site F Summary Plan Showing Grid System Established for the Remediation and Location of Main Structures and Sampling Locations Prior to Start of Remediation G Results of Auditor’s Sampling H Additional Data Provided by Enterra Joint Venture & Related Correspondence
CD’S THAT FORM PART OF THIS REPORT Dames & Moore CD Contents:
Area A Audit Report and Appendices
Submission to EPA on Clean Up to the Extent Practicable
Fate & Transport and Human Health Risk Assessment, Gasholder 1, 2 and Tar Pit, Former West Melbourne Gasworks Site
Enterra Joint Venture CD Contents:
CD1 – CD5 Site Validation Report Area A – Soil Report
CD01 Groundwater Data
LIST OF SUPPORTING DOCUMENTS
“Fate & Transport and Human Health Risk Assessment, Gasholder 1, 2 and Tar Pit, Former West Melbourne Gasworks Site, Docklands Victoria” Prepared by Dames & Moore, reference 37858\005\report\FT&HRA_Rev0.doc, November 2001.
“A Submission to the Environment Protection Authority on the Practicable Extent of Clean-up at Area A – West Melbourne Gasworks Site, Melbourne Docklands” Dames & Moore report ref 37858\005\report\Extent Pract Area A Rev B 0.doc, dated February 2002.
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TABLE OF CONTENTS (cont’d)
“Site Validation Report – Area A – Soil Report, Former West Melbourne Gasworks” prepared by Enterra Joint Venture, Reference: J700001A, 27 November 2001, revised February 2002.
“Site Validation Report – Area A – Groundwater, Former West Melbourne Gasworks” prepared by Enterra Joint Venture, Reference: J700001A R10, 12 November 2001, revised February 2002.
“North South Road Stockpile Sampling Program Environment Assessment Report” Volumes 1-3, Prepared by Egis Consulting Australia Pt Ltd, August 2000
“Final Concept Development Report for Enterra Joint Venture” Coffey Geosciences Pty Ltd, Report No E13635/2-CC, 13 August 1999.
“Groundwater Assessment of the Proposed Containment Area, Former West Melbourne Gasworks Site – Revised Final Report” Egis Consulting, reference VP8107.002.Rev2, September 1999.
“Site Specific Clean up Criteria for the Former West Melbourne Gasworks Site and the Victoria Harbour Precinct” Egis Consulting, reference VP7978.001.001.Rev0, December1998.
“Assessment of Soil and Groundwater Contamination at Victoria Harbour Precinct, Melbourne Docklands – Factual Report” Volumes 1,2 & 3 Golder Associates, CH2M Hill and Woodward- Clyde, December 1997
“The Australian Gas Association Site Remediation Task Force – Draft Guidelines for the Assessment and Management of Gasworks Sites” prepared by CMPS&F (Egis) reference SE102.002.005.RevC, February 1997.
“Site Characterisation. Victoria Harbour Precinct” prepared by CMPS&F Environmental, February 1997.
“West Melbourne Gasworks Draft Investigation” prepared by CMPS&F Environmental, April 1995.
“Phase II Investigation of Contamination of the West Melbourne Gasworks Site” Prepared by Camp Scott Furphy Ltd, January 1994.
EPA Notice dated 15th August 1994 directing Gas and Fuel Corporation of Victoria to take measures specified to clean up the land known as the former West Melbourne Gasworks.
“Environmental Audit Report: Former West Melbourne Gasworks Site” by Rick Graham Environmental Auditor – Sinclair Knight, reference 5V407.a02:RAG:rgz:25/1/94, 25 January 1994.
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REPORT ENVIRONMENTAL AUDIT AREA A – WEST MELBOURNE GASWORKS SITE for Docklands Authority Term of Appointment of Auditor December 1993 – December 2003 Location of the Site Area A Portion of Land bound by Piggot Street, Footscray Road, Blythe Street, and North Wharf Road at Melbourne Docklands, part of the property known as the former West Melbourne Gasworks and described in EPA Clean Up Notice dated 15 August 1994. Property Location Details Area A of the Gasworks site occupies part of the land described (Certificate(s) of Title) in the certificates of title: Volume 1016 Folio 076; Volume 2389 Folio 640; Volume 2416 Folio 077; Volume 3000 Folio 980; Volume 3118 Folio 563; Volume 3798 Folio 565; and Volume 3476 Folio 519 See section 5.1 for Australian Map Grid Co-ordinates. Municipality Melbourne Docklands - City of Melbourne, Victoria Current Zoning of the Site 1MU1 Mixed Use Docklands Victoria Harbour in Part 4 of the Docklands Planning Scheme Proposed Beneficial Use(s) Considered Beneficial uses relevant to Commercial, Open Space and Residential (High Density) segments Current Owner/Occupants of the Site State of Victoria: Department of Treasury & Finance (Owner). Docklands Authority (Occupier). Person Requesting Audit Mr Gordon Anderson, Technical Manager, Docklands Authority, (since retired and now represented by Mr Tom Graze of the Authority at time of completion of this Audit). Date of Request for Audit 16 September 1998 Date EPA Informed & Reference 17 September 1998 by Dames & Moore letter, reference KM:sa\\MEL-SVR1\JOBS\37858\002\Proj Manag\EPAinform.doc Completion Date of Audit February 2002 Assessment/Remediation Consultant(s) IT Environmental (Australia) Pty Ltd, on behalf of Enterra Joint Involved Venture. Laboratories Utilised Gribbles Analytical Laboratories Pty Ltd; Australian Laboratory Services Pty Ltd. Summary of Supporting “Site Validation Report – Area A – Soil Report, Former West Documentation Melbourne Gasworks” prepared by Enterra Joint Venture, Ref: J700001A, 27 November 2001 updated February 2002 – and “Site Validation Report – Area A – Groundwater, Former West Melbourne Gasworks” prepared by Enterra JV, Ref: J700001A R10, 12 November 2001, updated February 2002, and documents as referenced by EnterraJV and the Auditor including those listed in the Table of Contents of this report.
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Assessor’s Opinion of the Site Enterra Joint Venture believe that Area A of the site has been sufficiently remediated by the removal of previous structures and disposal of contaminated soils, and validated with regard to acceptance criteria provided in documentation referenced. Enterra states that “all in-situ soils” and “all treated and/or re- used soils” and “imported fill material” that remains on site are “statistically well within acceptance criteria adopted by the health based risk assessment” and the “the remedial works have resulted in a site that substantially exceeds the requirements of the risk based criteria”. Auditor’s Opinion on Assessment Acceptable – see Sections 9 and 12 of this report Methods Assessor’s QA/QC Acceptable – see Section 12 of this report Auditor’s Opinion on Laboratory Acceptable – see Section 12 of this report Methods Laboratory(s) QA/QC Acceptable – see Section 12 of this report Acceptance Criteria Considered NEPM “Assessment of Site Contamination”, Dec 1999 Schedule B(1) Guideline on Investigation levels for Soil and Groundwater ANZECC/NHMRC Australian and New Zealand Guidelines for the Assessment and Management of Contaminated Sites, Jan 1992 Health and Ecological risk based soil quality criteria developed for the site by Egis Pty Ltd SEPPs, IWMP’s Guidelines, Policies Environment Protection Act, 1970 and Standards considered Environmental Auditor (Contaminated Land) Guidelines for Issue of Certificates and Statements of Environmental Audit, EPA Victoria Publication No. 759 May 2001 State Environment Protection Policy (SEPP) “Groundwaters of Victoria” December 1997 State Environment Protection Policy (SEPP) “Waters of Victoria” 1988 including Schedule F7 Waters of the Yarra Catchment 1999. Industrial Waste Management Policy (IWMP) (Waste Acid Sulphate Soils) No S86, Government of Victoria Aug 1998. NEPM “Assessment of Site Contamination”, Dec 1999. AS4482.1-1997 “Guide to Sampling and Investigation of Potentially Contaminated Soil, Part 1: Non-Volatile Substances” September 1997. AS4482.2 – 1999 “Guide to the Sampling and Investigation of Potentially Contaminated Soil, Part 2: Volatile Substances” September 1999. Guidelines for Laboratory Analysis of Contaminated Soils” ANZECC, August 1996 ANZECC Australian Water Quality Guidelines for Fresh and Marine Waters, November 1992
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NH&MRC ARMCANZ Drinking Water Guidelines 1996 ANZECC/ARMCANZ (2000) Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000). ANZECC/NHMRC Australian and New Zealand Guidelines for the Assessment and Management of Contaminated Sites, Jan 1992 Victorian Environment Protection (Prescribed Waste) Regulations 1998 EPA Information Bulletin “Classification of Wastes”, Publication No.448, September 1995 Groundwater Quality Considered Risks are considered acceptable – See Section 13 of this report. Notwithstanding this opinion, a groundwater monitoring program is required to be undertaken initially by Enterra JV as part of their contractual obligations, and this audit is conditional on, and makes recommendations with regard to continuing monitoring by the Docklands Authority or its successors. Nature and Extent of Continuing Risks Soils contaminated with concentrations of PAHs, TPHs, MAHs, sulphate, ammonia, cyanide, metals and some pesticides at levels within acceptance criteria developed for the site, and groundwater contaminated at levels that may be a risk to some beneficial uses. Results of Audit The site is considered acceptable for high density residential use, open space (non-recreational), commercial and/or industrial use. It is also concluded that the level and extent of remaining contamination is unlikely to represent a health or environmental risk to neighbouring sites or the environment. Soil and groundwater contamination also remains present on neighbouring land beyond the boundaries of the audited site. Acceptable Beneficial Uses High Density Residential, Open Space (non-recreational), Commercial and/or Industrial. Management Requirements A Soil and Groundwater Management Plan is required to be prepared for the site encompassing all likely activities on the site that involve management of soils and/or groundwater including the following: Preparation and implementation of a Groundwater Management Plan including a minimum monitoring period. Appropriate management of any intrusive excavation works Maintenance of the integrity of the installed marker layer to identify the presence of soils classified as “D3” It is also recommended that: The groundwater on the site not be abstracted for beneficial uses of groundwater precluded by contamination. All plans prepared for a site development, or any subsequent changes to approved plans, or any changes to the S&GWMP in respect of soil and groundwater issues, should be subject to approval of an EPA appointed Environmental Auditor, or the EPA.
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ENVIRONMENT PROTECTION ACT 1970
STATEMENT OF ENVIRONMENTAL AUDIT
I, Kenneth N Mival, of URS Australia Pty Ltd, a person appointed by the Environment Protection Authority (“the Authority”) under the Environment Protection Act 1970 (“the Act”) as an environmental auditor for the purposes of the Act, having:
1. been requested by Mr Gordon Anderson of the Melbourne Docklands Authority (subsequently Mr Tom Graze of the Authority) to issue a certificate of environmental audit in relation to the site located at Area A of the former West Melbourne Gasworks site part of land bound by Pigott Street, Footscray Road, Blythe Street and North Wharf Road in Melbourne Docklands (‘the site”) owned/occupied by the Department of Treasury and Finance of the State of Victoria and the Docklands Authority respectively;
2. had regard to, among other things:
i. guidelines issued by the Authority for the purposes of Part IXD of the Act;
ii. the beneficial uses that may be made of the site; and
iii. relevant State environment protection policies/industrial waste management policies, namely:
• State Environment Protection Policy “Groundwaters of Victoria” December 1997
• State Environment Protection Policy “Waters of Victoria” 1988 Schedule F7 (Waters of the Yarra Catchment) 1999
• Industrial Waste Management Policy (IWMP) (Waste Acid Sulphate Soils) No S86, Government of Victoria Aug 1998.
in making a total assessment of the nature and extent of any harm or detriment caused to, or the risk of any possible harm or detriment which may be caused to, any beneficial use made of the site by any industrial processes or activity, waste or substance (including any chemical substance); and
completed an environmental audit report in accordance with section 53X of the Act, a copy of which has been sent to the Authority.
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HEREBY STATE that I am of the opinion that:
1. The site is suitable for the following beneficial uses subject to the conditions attached thereto:
i. High Density Residential Use; ii. General Open Space (Passive non-recreational use only); and iii. Commercial or Industrial Use. Subject to the following:
• All owners of the site, all occupiers and those made responsible for management of all parts of the site, including future dub-divisions, should be provided with a copy of this Statement of Audit, and also be provided with access to the site Environmental Management Plan (EMP) the preparation of which is also a condition of this Statement. The EMP that is relevant to this Statement of Audit should also include the following conditions: a) Preparation and implementation of an appropriate soil and groundwater management plan (S&GWMP) that includes a minimum monitoring period and provision for on- going management of groundwater where indicated. b) Engineered structures including the buildings, yards and open areas around buildings, pavement & parking areas, should be designed so that they are substantially covered with concrete, sealed surfaces or landscaping, that does not permit casual access to the underlying soils. c) No residential or commercial occupation be permitted of any basement areas other than reasonable access by building manager or maintenance staff, or for parking of cars or similar by others. d) Basement ventilation should be consistent with that normally provided for a basement car park. e) Appropriate management of any intrusive excavation works on the site in accordance with provisions of the S&GWMP f) Maintain the integrity of the marker layer where placed to identify the presence below of soils classified as “D3”. g) Monitor and maintain the integrity of low permeability bund walls placed on the perimeter of the site to restrict potential migration of contaminants on and off-site. h) Piles and deeper foundations and basement works should be constructed of concrete resistant to sulphate soils. i) It is recommended that the groundwater on the site not be abstracted for potential beneficial uses of groundwater precluded by contamination including: agriculture parks and gardens (irrigation), stockwatering and primary contact recreation. j) All plans prepared for, or any subsequent changes to approved site development plans, or to the S&GWMP in respect of soil and groundwater issues, and the monitoring and management of groundwater, or any proposal to extract groundwater for any purpose, should be subject to approval of an EPA appointed Environmental Auditor, or the EPA.
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k) Vegetable and fruit gardens should not be established on properties on the site, unless a minimum 500mm of 'clean' soil is provided in areas where re-used D1 class soils remain accessible. The condition of the site is detrimental or potentially detrimental to any (one or more) beneficial uses of the site. Accordingly, I have not issued a Certificate of Environmental Audit for the site in its current condition, the reasons for which are presented in the environmental audit report. The terms and conditions that need to complied with before a CeHicate of Environmental Audit may be issued are set out as follows:
Remediation on site, or removal of all soils from the site, contaminated with residual polycyclic aromatic hydrocarbons (PAH), petroleum hydrocarbons (TPH), monocyclic aromatic hydrocarbons (MAH), metals, cyanide, ammonia, and pesticides, including both re- used treated backfill soils and underlying Coode Island Silt Clay, to levels that permit any beneficial use; Remediation on site or removal of all groundwater contaminated with PAHs, TPHs, MAHs, cyanide, ammonia, and metals to levels that permit all beneficial uses appropriate to the relevant segment of each aquifer;
Other related information: As discussed with the Environment Protection Authority, soil and groundwater pollution which potentially may impact on Area A (the site), j?om Area B of the former West Melbourne Gasworks, and the groundwater and soils that remain on Area A of the site, have been cleaned up only to the extent practicable following consultation with and advicepom the EPA as given in a letter dated 21 February 2002 ref 36567/27990 part 2, therefore periodic review of the 'jrracticability" of clean-up of any remaining contamination is also required.
This Statement forms part of an environmental audit report prepared by Dames & Moore, titled "Stafutory Environmental Audit, Area A - West Melbourne Gasworks" reference: S:\37858\005\Report\GasworksAuditRepRevOdocdated February 2002. Further details regarding the condition of the site may be found in the environmental audit report and should be read in conjunction with this Statement.
Dated:
Signed: ......
K N Mival of Dames & Moore Pty Ltd
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15 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 12
1. INTRODUCTION
This Environmental Audit Report has been prepared by Ken Mival (EPA accredited Environmental Auditor - Contaminated Land) of Dames & Moore Pty Ltd, a division of URS Australia Pty Ltd. The Audit was undertaken at the request of Mr Gordon Anderson, Technical Manager, on behalf of John Tabart, CEO, of the Melbourne Docklands Authority. The Docklands Authority has subsequently been represented for this audit by Mr Tom Graze, General Manager Development and Infrastructure, since Mr Anderson’s retirement.
This report concerns an Environmental Audit conducted on part of the former West Melbourne Gasworks site, known as Area A, located on land bound by Pigott Street, Footscray Road, Blythe Street and North Wharf Road in Melbourne Docklands, City of Melbourne. The location of the site is indicated in the attached Locality Plan – Figure 1.
The land occupied by the former West Melbourne Gasworks is subject to a Clean Up Notice issued on 15 August 1994 to the Gas & Fuel Corporation of Victoria, then owners and occupiers of the site.
This Audit report relates only to the western portion of the former Gasworks Site, specifically that parcel of land defined by the Australian Map Grid coordinates detailed in Table 1.1.
Table 1.1 Co-ordinates of Area A of West Melbourne Gasworks Site
Point Easting Northing 1 318969.993 5811945.924 2 319102.350 5812012.230 3 319164.865 5811741.505 4 319130.230 5811745.220 5 318992.004 5811794.300 6 318955.137 5811805.572
These coordinates define an area of the former Gasworks, referred to as ‘Area A’. The remainder of the Gasworks site subject to the Clean up Notice, known as Area B and the Gas Regulating Station (GRS) will be referenced in separate audit reports when appropriate. The area audited is indicated in the attached Site Plan Figure 2.
The land subject to the audit was formerly zoned as PP17 – Port Purposes in the Port of Melbourne Planning Scheme and has been rezoned as 1MU1 – Docklands Victoria Harbour - Mixed Use in Part 4 of the Docklands Planning Scheme.
This audit represents the final phase in a long process that began in August 1993, when Mr Rick Graham of Sinclair Knight & Partners was engaged by the Docklands Authority to undertake an audit of the former West Melbourne Gasworks site. Mr Graham issued a Statement of Environmental Audit in January 1994 to the Docklands Authority that indicated the site was unsuitable for issue of a Certificate of Audit as the “concentrations of contaminants in soils exceed concentrations which are generally considered acceptable on sites used for residential, open space or commercial uses, and, an assessment of the risks to human
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16 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 13 health of future occupants of the site confirms that the risks presented by contaminants at existing concentrations are unacceptably high”.
As a result, on 15 August 1994, the EPA issued a Clean Up Notice on the site to the Gas & Fuel Corporation of Victoria directing the said party to clean up the land to “to remove contaminants and rehabilitate the land”. The land was also added to the EPA’s list of Priority Contaminated Sites.
Subsequent to Mr Graham’s audit, several further studies were undertaken by Docklands up to 1998 to explore the extent of contamination on the site both in the soils and groundwater. These studies are listed in the references to this audit report and were referenced by this Auditor as part of the audit process.
A parallel process was started by Docklands Authority to find a developer to undertake remediation of the Gasworks site as part of the development of the whole of the Victoria Harbour Precinct of Docklands. Two preferred bidders were identified in 1997 and they organised the second phase assessment of the whole of the Precinct, including the Gasworks area. However, the process was interrupted in 1998 when the Authority could not reach agreement with the preferred bidders on the extent of remediation. As a result, the Docklands Authority negotiated with one of the bidders through into 1999, whilst continuing with remediation of the former Gasworks portion of the Victoria Harbour Precinct as a separate process directly appointing a remediation contractor, Enterra Joint Venture (a Joint Venture of Abi Group and IT Environmental).
During this process, this Auditor was initially (in 1997) proposed by one of the unsuccessful bidders as the intended Auditor for the wider area of the Victoria Harbour Precinct that includes the Area A part of the former West Melbourne Gasworks. This was provisionally accepted by both bidders and by the Docklands Authority, with the intention of the Auditor being novated to the winning bidder in the development agreement once it was signed. The bidding process did not result in a successful developer and therefore, the appointment of the Auditor for the land comprising Victoria Harbour never eventuated. This situation was discussed with the EPA at the time in a number of meetings known as the Docklands Audit Panel, although no formal notice was provided to EPA at the time as no actual request for an audit had been made. This was clarified in Dames & Moore’s letter to the EPA of August 1998.
The Auditor was subsequently appointed directly by the Docklands Authority in September 1998 to undertake an audit of only the Gasworks part of the Victoria Harbour Precinct Site, with the eventual aim of providing a Statement of Audit for the Gasworks site to satisfy the conditions of the Clean up Notice.
With the agreement of the Auditor, a risk assessment was also started in 1998 by Egis Consulting on behalf of the Docklands Authority based on the previous studies, to establish risk based soil remediation target criteria for the site. This was reviewed by the Auditor and modified target criteria were developed for inclusion in a remediation contract based on the risk assessment and other factors such as aesthetic considerations (odour) and the potential for ecological risks.
The contract to remediate the whole of the former West Melbourne Gasworks site (excluding a portion known as the Gas Regulating Station (GRS)) was awarded to Enterra Joint Venture in mid 1999 with a planned completion date of September 2000. Remediation Work Plans were reviewed by the Auditor and the whole remediation process has been monitored at more than 100 site meetings and by numerous and frequent site visits. It has included monitoring of Enterra’s work methods on site, particularly the tracking
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17 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 14 of movement of soils; the periodic review of the soil management data-base set up by the contractor; and the continual review of validation data as it became available. This process is documented in this audit report and the remediation process in the attached validation report prepared by Enterra JV.
This audit has been conducted in accordance with section 53X of the Victorian Environment Protection Act 1970 and EPA “Environmental Auditor (Contaminated Land), Guidelines for Issue of Certificates and Statements of Environmental Audit”, Pub. No. 759, May 2001. The Auditor has exercised professional judgement and had regard and given due weight to Relevant State Environmental Protection Policies.
1.1 PURPOSE OF REPORT
The purpose of this audit is to evaluate whether the site is suitable for issue of a Certificate of Audit indicating that it is suitable for “any beneficial use” and if not, whether it is suitable for the intended high density residential, general open space (non-recreational), and commercial uses proposed by the Docklands Authority, a range of uses that is considered to be consistent with the intended zoning of the land. No information has been provided to the Auditor with regard to any future development within Area A of the former West Melbourne Gasworks area and therefore it has been assumed from the outset that the most sensitive use could be located anywhere within the area audited.
Therefore this audit assesses the health and environmental risks that may occur from exposure to contaminated soil, vapours and/or waters (including groundwater) that may be found at the site with respect to all of its potential beneficial uses. This includes the impact of the land on contiguous segments of the environment and adjacent land, and the possibility of adjacent land impacting adversely upon the environmental condition of the remediated subject land.
1.2 PARTIES INVOLVED
The pertinent parties involved in the remediation of the Former West Melbourne Gasworks site were as follows:
Site Owner(s): Department of Treasury & Finance
Site Occupier(s): Melbourne Docklands Authority
Environmental Site Assessor(s): IT Environmental (Australia) Pty Ltd, as part of Enterra Joint Venture, a Joint Venture with Abigroup Pty Ltd.
Primary Laboratory Used by Assessor(s): Gribbles Analytical Laboratories Pty Ltd
Secondary Laboratory Used by Assessor(s): Australian Laboratory Services Pty Ltd
Validating Laboratory used by Auditor: Australian Laboratory Services Pty Ltd
Remediation Contractor(s): Abigroup Pty Ltd, as part of Enterra Joint Venture, a Joint Venture with IT Environmental (Australia) Pty Ltd.
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2. AUDIT GUIDELINES
The environmental audit system is designed to provide:
• assurance to the community that a site is suitable for its intended use;
• assurance to prospective purchasers and other parties involved in property investment and development regarding the condition of a site and any restrictions attached to the use of that site;
• a link between the environmental condition of a site, the suitability of a site for use and the statutory planning process.
The Environment Protection Act 1970 (the “Act”) creates a mechanism under which “Certificates” or “Statements” of Environmental Audit may be issued by an EPA-accredited Auditor following the completion of an environmental audit with the procedures as set out in the Act.
Environmental audits are defined in Section 4 of the Act and their use is described in Section 53X. The definition of an “environmental audit” is:
“ a total assessment of the nature and extent of any harm or detriment caused to, or the risk of any possible harm or detriment which may be caused to, any beneficial use made of any segment of the environment by any industrial process or activity, waste, substance (including any chemical substance) or noise*.
*Note that in Section 3 of the Auditor Guidelines, the EPA states that “noise is not a relevant consideration when conducting an environmental audit (contaminated land) but is a factor that can impact on beneficial use”.
In conducting a statutory environmental audit, the Auditor must identify the beneficial use(s) that are to be protected for the site in question. The beneficial uses considered could include for example:
• human health and well being;
• maintenance and preservation of natural ecosystems and associated wildlife;
• groundwater quality;
• surface water quality;
• aesthetic enjoyment and amenity;
• productive capacity of land for agriculture, silviculture or horticulture; and
• integrity of artificial structures (with regard to corrosion, chemical degradation, fire or explosion risk related to contamination).
With respect to statutory audits of contaminated land, or potentially contaminated land, the primary function of the Environmental Auditor is to audit the status of the site in question in accordance with provisions of Section 53X of the Act.
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If the Auditor considers it appropriate, the Auditor will issue a Certificate of Environmental Audit, and an accompanying Auditor’s Report.
The Auditor must decline to issue a Certificate if the Auditor is of the opinion that contamination of the site renders the site detrimental or potentially detrimental to any beneficial use of the site.
For the purposes of auditing, the “site” subject to the environmental audit is defined “as the land at a premises being audited (as delineated by title boundaries) and any other relevant element of the environment” (Vic EPA, May 2001).
“Land” refers to the element of the environment which includes:
• soil, fill and rock including vapour and liquids within the void spaces, in the unsaturated zone of the soil profile and/or weathered rock; and
• sub-aqueous sediments.
The EPA has prepared guidelines in relation to statutory environmental audits, which are entitled “Environmental Auditor (Contaminated Land), Guidelines for Issue of Certificates and Statements of Environmental Audit”, Pub. No. 759, May 2001.
The Auditor takes into account relevant State Environmental Protection Policies, Industrial Waste Management Policies and Regulations when conducting a statutory environmental audit. These include for example:
• State Environmental Protection Policy (Waters of Victoria) and catchment specific schedules as appropriate for the audit in question;
• State Environmental Protection Policy (The Air Environment);
• State Environmental Protection Policy (Groundwaters of Victoria);
• Industrial Waste Management Policy (Waste Minimisation);
• Industrial Waste Management Policy (Waste Acid Sulphate Soils);
• Environment Protection (Prescribed Waste) Regulations 1998.
Guidelines that may be referenced include:
• EPA Information Bulletin 448 "Classification of Wastes" Sept 1995; and
• “Guidelines for the Laboratory Analysis of Contaminated Soils” prepared by ANZECC, August 1996.
It also includes reference to relevant Australian Standards and National guidelines where recognised and/or required by the EPA of Victoria including:
• National Environment Protection Measure (Assessment of Site Contamination), December 1999, prepared by the National Environment Protection Council (NEPC);
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• Australian Standards AS4482.1 & 2 –1997 & 1999 “Guide to Sampling and Investigation of Potentially Contaminated Soil, Parts 1 & 2: Non-Volatile & Volatile Substances”
Additional references for auditors and for the auditing system include those listed in Section 18 of this report (that have been directly or indirectly considered as part of this audit).
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3. SCOPE OF AUDIT
In assessing the present environmental condition of a site, the Auditor may review any previous site contamination assessments and all relevant documentation applying to the subject site, which may comprise at least the following:
• the basis for the identification of contamination on the site, including site history, land uses, planning, zoning and the process of site identification;
• relevant correspondence;
• demography of the locality;
• geology/hydrogeology of the area;
• quality of water resources, including groundwater and stormwater runoff;
• chemical and physical characteristics of the soil and the contaminants;
• characterisation of contamination, including the nature and mobility of contaminants, their depth and spatial distribution; and
• licences and/or trade waste agreements from environmental, waste management or waste water management agencies.
This report prepared by the Auditor reflects the recommended approach to assessing contaminated sites outlined in the NEPM, Assessment of Site Contamination, December 1999.
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4. DOCUMENTS REVIEWED
Relevant information that has been referred to for the purposes of this audit include the following:
• Sinclair Knight (January 1994) “Environmental Audit Report: Former West Melbourne Gasworks Site” prepared by Mr Rick Graham Environmental Auditor, Contaminated Land.
• Environment Protection Act (1970) Section 62A Clean up Notice dated 15 August 1994.
• Golder Associates, Woodward-Clyde and CH2M HILL (December 1997) “Assessment of Soil and Groundwater Contamination at Victoria Harbour Precinct, Melbourne Docklands”.
• CMPS&F (February 1997) “Docklands Authority, Site Characterisation, Victoria Harbour Precinct”.
• CMPS&F (February 1997) “Australian Gas Association Site Remediation Task Force. Draft Guidelines for the Assessment and Management of Gasworks Sites” (provided in confidence to the Auditor for his reference)
• Egis (CMPS&F) (December 1998) “Site Specific Cleanup Criteria for the Former West Melbourne Gasworks Site and the Victoria Harbour Precinct”.
• Egis Consulting (September 1999) “Revised Final Report on Groundwater Assessment of the Proposed Containment Area, Former West Melbourne Gasworks Site”.
• Enterra Joint Venture (26 October 1999) “Construction Management Plan for the Remediation of the West Melbourne Gasworks Site” (Revision 2)
• Coffey, (5 November 1999) “Former Gasworks Site, Encapsulation of Charles Grimes Bridge Road. Interim Goetechnical Design Report”
• Docklands Authority, IT Environmental (Australia) Pty Ltd & Abigroup Contractors Pty Ltd (August 1999) “Gasworks Site Remediation Contract”
• Review of bid proposals by prospective remediation contractors in terms of acceptability of the proposed outcome in relation to proposed beneficial uses
• Enterra Joint Venture (September 1999 to October 2000) “Remediation Action Plan for the Remediation of the West Melbourne Gasworks Site” (Encompassing Revisions 1 through 7 inclusive)
• Various remediation methodologies as put forward to the Auditor by Enterra during the course of numerous meetings both prior to and during the remediation contract as discussed in Section 11 of this report
• Enterra Joint Venture (Various) Weekly Environmental reports for the remediation of the West Melbourne Gasworks.
• Enterra Joint Venture (Various) Monthly Groundwater Monitoring Reports for the Remediation of the West Melbourne Gasworks.
• IT Environmental (Australia) Pty Ltd (October 2000) “Ammonia Transport in Groundwater – Numerical Modelling”.
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• IT Environmental (Australia) Pty Ltd (March 2001) “Phase Separated Hydrocarbon Impact – Fate and Transport Assessment” (Draft only).
• IT Environmental (Australia) Pty Ltd (March 2001) “Phase Separated Hydrocarbon Impact – Quantitative Risk Assessment” (Draft only).
• Enterra Joint Venture (November 2001) “Remediation of West Melbourne Gasworks Site – Area A Validation Report” as revised Feburary 2002.
• Enterra Joint Venture (November 2001) “Site Validation Report – Area A – Groundwater, Former West Melbourne Gasworks” as revised February 2002.
• Enterra Joint Venture various correspondences incorporated into the revised validation report (Enterra CD 5) issued February 2002 addressing issues raised by the Auditor.
In addition to the above documents, the following activities were undertaken to assist in forming an opinion on the overall adequacy of the remediation program:
• Attendance at over one hundred site meetings with relevant parties including the remediation contractor Enterra, a Joint Venture of Abi Group and IT Environmental (Australia) and its consultants, (including the IT staff of Enterra JV as the environmental assessor), Principal’s Technical Representative, Contract Superintendent, Docklands Authority, Environment Protection Authority and the Representatives of Unions employed on the site and their consulting advisers.
• Regular correspondence with the Environment Protection Authority, Client, Principal’s Technical Representative, Superintendent and Contractor regarding pertinent issues and the overall progression and implementation of the site works according to contract requirements.
• Regular monitoring visits to review the remediation works throughout the duration of the contract from 1999 to 2001, during which over eighty monitoring visits were undertaken by the Auditor and/or the Auditor’s Representatives.
It has also included the preparation by the Auditor’s support team of groundwater fate and transport models and human health risk assessments to support the audit conclusions regarding potential human health and ecological risks on the site. These included:
• Dames & Moore (July 2001) “Contaminant Fate & Transport Modelling, at West Melbourne Gasworks Site, Docklands”.
• Dames & Moore (September 2001) “Human Health Risk Assessment, Gasholder 2, Former West Melbourne Gasworks Site, Docklands”
• Dames & Moore (November 2001) “Fate & Transport and Human Health Risk Assessment, Gasholder 1, 2 and Tar Pit, Former West Melbourne Gasworks Site, Docklands Victoria” Prepared by Dames & Moore, reference 37858\005\report\FT&HRA_Rev0.doc, November 2001
The latter report supersedes the July 2001 and September 2001 modelling and risk assessment reports.
It also includes the preparation of a submission to the EPA on the practicable extent of remediation undertaken on the site:
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• “A Submission to the Environment Protection Authority on the Practicable Extent of Clean-up at Area A – West Melbourne Gasworks Site, Melbourne Docklands” Dames & Moore report ref 37858\005\report\Extent Pract Area A Rev B 0.doc, dated February 2002.
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5. SITE DESCRIPTION
5.1 SITE LOCATION & DESCRIPTION
The former West Melbourne Gasworks site is located in the City of Melbourne municipality between Pigott Street and North Wharf Road within the Victoria Harbour Precinct in the Docklands Area. The overall Site is commonly known as the Former West Melbourne Gasworks and covers a total area of 7.68 hectares.
At the discretion of the Docklands Authority, the site was divided into two main sections, namely Areas A & B.
This Statement of Environmental Audit covers Area A only.
Area A encompasses a total area of 35,776.732m2 and incorporates a number of Certificates of Title, namely:
• Volume 1016 Folio 076;
• Volume 2389 Folio 640;
• Volume 2416 Folio 077;
• Volume 3000 Folio 980;
• Volume 3118 Folio 563;
• Volume 3798 Folio 565; and
• Volume 3476 Folio 519.
However, given that Area A encompasses only part of some of the above mentioned Titles, Area A was surveyed to Australian Map Grid (AMG) coordinates by a licensed surveyor subcontracted by Enterra. As such, Area A is best defined by the AMG easting and northing coordinates contained in Table 5.1.
Table 5.1 Coordinates Defining the Boundaries of Area A of the West Melbourne Gasworks Site Point Easting Northing 1 318969.993 5811945.924 2 319102.350 5812012.230 3 319164.865 5811741.505 4 319130.230 5811745.220 5 318992.004 5811794.300 6 318955.137 5811805.572
A site plan showing the relationship between Area A and Area B with the overall Gasworks site and the AMG coordinates of the points defining Area A is included as Figure 2 of Enterra’s Validation Report for Area A. We also refer to the Site Plan Drawing Number 8259-07-CO-ORDS, prepared by the clients
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Technical Representative (GHD) that indicates the boundaries of the site and highlights the audited Area A. This plan is included in Appendix A of this report for reference.
5.2 ON-SITE ACTIVITIES AND USES
At the time of reporting, no activities were being undertaken on the Area A site. The overall former West Melbourne Gasworks site is presently surrounded by a 1.8 metre chain mesh fence and machinery has been excluded from the area since completion of physical remediation of that portion of the site in order to limit potential for recontamination. The remaining continuing remediation activities and processes were, at the time of completion of this audit, restricted to Area B of the site.
Details of the historical activities previously undertaken on the overall site are discussed in Section 5.6 of this report and a brief discussion on land uses and operations in and adjacent to Area A, are discussed below.
5.3 NEIGHBOURING LAND USES
The site is surrounded by the following:
• North – Victoria Dock is located approximately 200m from the northern boundary of the site, and includes proposed commercial developments of Victoria Harbour Precinct from the gasworks boundary to the existing Victoria Dock quayside. A new development including localised soil remediation, is currently in progress to the north east of Area A for an office development on the north side of Piggot Street for the National Australia Bank. Further to the north east of the site are other commercial developments including Colonial Stadium and the Comtechport Precinct, and to the north of Victoria Dock, the New Quay development, the Film and Studio site and proposed North Western Precinct within the former Business Park Precinct of Melbourne Docklands.
• East – The area east of the overall gasworks site is land that was formally a petrol station site, train sheds and the Queens Warehouse that now houses the Fox Vintage Car Collection including restoration workshops and administration building. Remediation is also about to take place on portions of this land. Further to the east of the Queens warehouse site, between old Footscray Road and Wurundjeri Way is the proposed Batman’s Hill Precinct development site. Beyond Wurundjeri Way are the metropolitan railway and VicRail rail lines, Spencer Street Station, and the Melbourne CBD. The area of the gasworks to the east of Area A is now vacant, but formerly included Charles Grimes Bridge Road that was constructed over many of the former gasworks structures including tar pits, gasholders, the former ammonia plant and other facilities related to gasworks operations. These are currently also being remediated and are discussed where relevant to this report.
• South – The Yarra River is located approximately 60m south of the site boundary beyond the adjacent North Wharf Road and former cement storage silos and wharfage relating to the former coal handling operations for the gasworks when it was operating. The area south of the Yarra River comprises the Yarra Waters Precinct of Melbourne Docklands between Lorimer Street and the Yarra which currently has four residential towers under construction. A number of industrial/commercial properties are located 350metres or more from the site, further to the south of Lorimer Street in South Melbourne.
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• West – The remainder of the Victoria Harbour Precinct includes former stables for the City of Melbourne, various Port installations including docks and warehouses, and the intersection of Victoria Dock and The Yarra River, the Bolte Bridge and Melbourne Port.
5.4 GEOLOGY & HYDROGEOLOGY
5.4.1 Geology
At the site sediments of the Quaternary Yarra Delta Group rest on uneven pre-Quaternary terrain of Tertiary sediments and/or residual soils of the Older Volcanics and Silurian siltstone formations inclined generally to the southwest at a low angle. The following units of the Quaternary and Tertiary formations are recognised at the site in sequential order from the top, and including the imported fill now located on Area A of the site. The general arrangement of the strata at the site are illustrated in the conceptual geological model in Figure 5 attached.
• Remediated fill, typically in the range 2m to 5m deep, comprising mainly imported crushed rock, but also including crushed concrete and reworked Coode Island Silt from within the gasworks site; Older Volcanics clays and re-used fill soils imported from the Wurundjeri Way excavations in Docklands (North South Road); Brighton Group sandy clay sediments, and crushed mudstone/siltstone of the Silurian excavated from various locations around the City of Melbourne.
• Coode Island Silt (CIS) unit, extending to depths between about 7m and 17m (Coffey, 1999), is described as a marine clay of high plasticity containing horizontal layers of siltier and sandier material. Silty sand and sand layers (up to 5 m thick) have been encountered at the base of CIS and are reported to exist in many parts of Yarra Delta area. The thickness of CIS at the site area generally appears to increase towards the south-west, with thickness in the range of 15m reported at the western end of the Area A. CIS encountered during the remediation works typically contained marine shells and shell fragments.
• Fishermens Bend Silt (FBS) unit, up to 15 m thick in the local region, comprises silty clay, fine sandy clay and clay. The upper surface of this unit is irregular due to erosion following deposition and prior to formation of the CIS deposits. Coffey (1999) reported that in the north-eastern corner of the Site (within what is now Area B), the CIS unit was relatively thin and FBS sediments were distinctly siltier and sandier than usual and generally a lighter brown or grey colour than the CIS. Enterra JV have reported that during their works, the thickness of FBS was noted as between 3 and 5 metres in that area. It may be present beneath the CIS in Area A but was often not distinguished from it during the investigations on the site. The Egis 1999 Groundwater report indicates that it believed the thickness of FBS to be of the order of 0.5 to 11.8metres across the Gasworks site. Subsequent investigations by Enterra for the Fate & Transport Modelling indicated that it could be discontinuous as the depth of CIS increases substantially westwards beneath Area A.
• Moray Street Gravels (MSG) unit aquifer consists of gravel and sand with minor layers of silt and clay. Review of available data indicates that it can be up to around 21 m thick in the Yarra Delta, but is reported by Enterra to be around 10 to 15m thick on the site. Egis indicated a range of 3.1 to greater than 8.9 metres for the MSG. The MSG does not outcrop on the Site, but is known from deeper boreholes, particularly for the Bolte Bridge construction to be present as a continuous aquifer across the area.
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• Werribee Formation unit typically comprises sands and gravels overlain by silts and clays. This formation was not encountered beneath Area A, however it was encountered in two boreholes located on the eastern boundary of Area B.
• In the north-eastern part of the Area B of the Gasworks site orange clay described as “Residual Older Volcanics” (OV) has been encountered in a number of bores on the site from depths 10 - 11 m below ground surface and appears to separate the FBS from older underlying formations. These were not encountered beneath Area A and are unlikely to influence this part of the site.
• Below the Tertiary sediments described above, the Silurian siltstone basement formation underlies the site area and was encountered in one bore on the overall gasworks site at a depth of about 30m below ground surface.
5.4.2 Hydrogeology
Our understanding of the hydrogeology on the site is based on a number of sources, but is principally derived from the borehole monitoring data generated during the various investigations prior to and during the remediation of the Gasworks site, and in the adjacent Victoria Harbour Precinct. It is also based on the review of the groundwater investigations undertaken by Egis documented in their revised final Groundwater report (Sept 1999) included with the documentation on CD supplied with the Enterra report, and also the Enterra Groundwater report itself.
Our understanding of the groundwater regime on the remainder of the site (Area B and the GRS) has also been reviewed and is separately discussed in a groundwater modelling report titled “Fate & Transport and Human Health Risk Assessment, Gasholder 1, 2 and Tar Pit, Former West Melbourne Gasworks Site, Docklands Victoria” dated November 2001, Ref 37858 005-7055, that supersedes earlier reports undertaken by the Auditor (and provided to the EPA) as part of a risk assessment to examine the potential for migration of contaminants into Area A from sources that may remain within Area B of the site. These documents are included on the CD of supporting documentation attached to this audit report for reference. The remaining relevant documents are supplied on the CDs provided by Enterra with their reports supporting this audit report.
As part of the remediation of the site, the removal of the fill soils effectively removed the impacted groundwater in that aquifer, and the excavation was also kept dry by pumping prior to placement of backfill, during which any polluted groundwater drawn into the site from elsewhere was intercepted and managed.
Inferred groundwater contours based on pre-1999 and post-1999 data indicate that the activities associated with remediation of the site have also temporarily lowered groundwater levels in the underlying CIS. In considering the variation in groundwater levels and contours in the CIS across the site during the remediation program, it must be considered that groundwater monitoring bores sealed into the clayey soils will also act like peizometers and water levels may vary up and down due to unloading and backfilling of the site changing the applied stresses.
No information for the MSG groundwater levels was available prior to 1999 or FBS groundwater levels prior to 2001. The studies undertaken prior to the start of site remediation were reviewed to assess potential groundwater flows and final RLs of the water table, once recovered back to equilibrium.
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Yarra Delta Group sediments host several aquifer systems. The Moray Street Gravels are considered to be the only major regional aquifer beneath the site with groundwater flowing in a south-east direction, and groundwater flow gradients reported to be “consistently around 0.002” (Egis 1999). This was examined prior to the start of remediation in order to assess the viability of a containment option and was discussed with the EPA at the time.
The study of the Yarra Delta geology by Egis (1999), indicated that groundwater in the MSG aquifer is likely to be confined within the aquifer by a contiguous layer of Coode Island Silt, and would be anticipated to discharge into Port Phillip Bay at some considerable distance from the site. It was therefore concluded at the time that the risk of potential impacts on receiving waters from pollution that may have entered the aquifer, was likely to be minimal.
This information was presented to the EPA in Dames & Moore’s letter dated 21 May 1999 following discussions with the EPA at a meeting of 12 May and responded to in the EPA’s letter of 9 June 1999, which indicated general concurrence with these considerations whilst requiring the remaining feasible beneficial uses of the groundwater in the MSG to be considered (industrial, buildings and structures and protection of ecosystems).
The overlying fill is considered to represent a system of perched aquifers of limited lateral extent and heterogenous nature. Within Area A of the site, almost all the original fill has now been excavated and either removed off-site or treated and replaced. Remediated or imported fill from a number of different sources (See Section 11.2) has been utilised in the remedial works undertaken. It is expected that these fill materials would have widely variable physical properties and permeabilities, although the preponderance of clayey material and weathered rock indicates a generally low mass permeability can be anticipated in the body of the fill.
The sediments of the CIS and FBS are usually grouped together as an aquitard, although it is anticipated that layers and lenses of sandier material within these units could form local, discontinuous aquifers. Previous investigations have reported a range of hydraulic conductivities for CIS and FBS sediments (refer Table 5.2 below). Due to their alluvial origin, the CIS is generally characterised by mass horizontal conductivities significantly greater than vertical. However, the FBS unit is reported to have horizontal and vertical permeabilities of a similar order, with the siltier and sandier parts of the FBS having mass permeability several orders of magnitude higher than the CIS.
Egis (1999) reported local groundwater flow within the CIS was to the east prior to commencement of remediation works. This is contrary to what would be considered a likely flow direction in the CIS which, due to the geography of the site and its location, would be anticipated to be toward Port Phillip Bay or at least north westwards or south westwards towards Victoria Harbour and the Yarra River. At the time of reporting by Egis, this reversal appeared to be due to depressions in the watertable identified at bores BH2, BH6 and BH7 (Egis 1999) and may have been a result of local influences (such as drainage into deep sewers or drains).
The overall low vertical permeability of the more clayey CIS and FBS sediments would suggest little or no hydraulic connection between the MSG and overlying units. This would be anticipated to be the case considering the hydraulic characteristics of the CIS, FBS and MSG and was considered an important issue in assessing the potential for groundwater and contaminant migration on the site.
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Table 5.2 Hydraulic Conductivity Data.
Formation Horizontal K Vertical K
CIS (Egis, 1999) Between 3.8e-9m/sec and 2.8e- between 1.1e-10m/sec and 5.1e- 5m/sec (0.0003 m/d – 2.42 10m/sec (9.5e-6m/d – 4.4e-5m/d) m/d) CIS (Coffey, 1999) 2.2e-11m/sec or less (1.9e-6 m/d) CIS (in Coffey, 1999) 1.5e-7 m/sec (0.013m/d) between 1e-10 m/sec and 1e-8 m/sec (8.6e-6 m/d – 8.6e-4 m/d), increasing in sandier materials to greater than 1e-8 m/sec FBS (slug test data, analysed Bouwer and Rice method: by IT Environmental Pty Ltd BH40 – 0.1 m/d, BH42 – 0.05 and independently calculated m/d, BH43 – 0.085 m/d, BH44 from source data by Dames & - 0.04 m/d, BH49 – 0.1 - Moore, 2001) 0.0035 m/d, BH50 – 0.05 m/d; Hvorslev method: BH40 – 0.25 m/d, BH44 - 0.073 m/d, B&R Method - BH49 - 0.0035 m/d. Median: 0.05 m/d
A layer characterised by sandier lithology at what appeared to be the contact between CIS and FBS, was encountered in most of the bores in the general area of the north eastern part of the overall site in the vicinity of Gasholder 2 in Area B. This layer comprises sandy silt or silty sand, 0.9 to 4.3 metres thick, and was investigated as a potential local aquifer. However, the sandy layers were not found to persist into Area A of the site, not being found in bores located adjacent to and slightly east of, the A/B boundary, in boreholes on Area A itself, or to the north of the gasworks where recently investigated for the new development by Egis for Lend Lease (direct communication to Auditor), and it appears to be a local feature only on Area B.
Historically infiltration recharge of the aquifers at the site would have been limited due to the paved and/or concrete sealed surfaces of the former Gasworks. Given Area A’s proposed future high density residential usage and the generally low permeability of the backfill soils used, it is considered that infiltration recharge of the aquifers will also be negligible once development is completed. This appears to already be indicated by the dry bores located in Area A where recharge has been very limited and it is dubious that the Fill could be considered an aquifer, at least in Area A, due to a lack of yield of groundwater. This could also be partly a seasonal effect as fluctuations in water levels were noted in many of the bores across the site that is relatively coincident with the seasons.
Previous site investigations undertaken by EGIS (1999) indicated negligible tidal influence in the CIS, however the MSG displayed some tidal influence with fluctuations in the order of 100mm noted and a directional shift fluctuating from an east-south-east direction to a south-east direction. It also indicated in
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31 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 28 it’s risk assessment report that tidal influence made a significant difference to the concentration of chemicals detected in some of the fill bores close to the receiving waters and outside of the gasworks site.
It is assumed that no groundwater extraction or usage is likely to continue in Area A after site remediation works have been completed. This is considered a realistic assumption due to the very low yield potential of the CIS/FBS formations and Fill aquifer, the lack of reliable groundwater in the Fill as indicated by the dry bores, and the poor quality (high TDS) of the groundwater in aquifers such as the CIS and MSG. This is discussed further below when considering “likely” beneficial uses of the groundwater.
Groundwater Quality & Beneficial Uses
The State Environmental Protection Policy (Groundwaters of Victoria) provides a guide for potential beneficial uses of groundwaters by allocating groundwater to five Segments which are defined by total dissolved solids (TDS) content of the groundwater. Using the most recent groundwater data provided in the Site Validation Report – Area A – Groundwater (Enterra October 2001- subsequently updated in February 2002 with data up to January 2002), the range of potential beneficial uses have been identified for each aquifer in Table 5.3.
Fill Material (A Wells)
Typically TDS values for the remediated areas of Area A of the gasworks exceed 3,500mg/L and lie within Segment C. Segment C includes maintenance of ecosystems, stock watering, industrial water use, primary contact recreation and building and structures. This is based on the values for bores located both in the fill material that is yet to be remediated, and in three monitoring bores re-established into the remediated soils on the site since completion of remediation. Of the new bores that have been installed to date, monitoring bore MW19A, and subsequently MW18A, were found to be dry following remediation and backfilling of Area A, whilst MW21A located on the boundary with Area B indicates a TDS appropriate to Segment C.
It is possible that initial recharge of the fill aquifer could also be considerably fresher in some areas as indicated by Monitoring Bore MW18A with a TDS of 1,100mg/L. MW18A is located within the remediated backfill which potentially indicates segment B. This lower TDS may be from dilution by recharge from rainfall subsequent to the remediation.
Recent analyses in later January 2002, found that both MW 18A and MW19A were now virtually dry and insufficient water remained for sampling. Field testing of the residual moisture in each bore indicated the TDS of what remains to now be closer to 1,800mg/L. MW21A in the remediated area of Area B indicates TDS exceeding 4,000mg/L and has increased to around 6,000mg/L since the beginning of 2002. It is therefore considered that Segment C is the most appropriate for the Fill Aquifer. This should be reviewed as part of any long-term monitoring program included in an environmental management plan for the site post remediation.
The water from the fill also exhibits a raised pH above 10 in both MW21A and MW18A. This appears to be due to the use of lime both to assist in remediation of the soils, and as a stabilising agent to reduce moisture content and assist in compaction. For treatment, lime was used up to as much as 10% by weight, and for compaction, a rate of 3 to 5% is normal practice by civil engineers. Previous investigations by this Auditor into lime as a hazard on a site audited at Bell Street Preston, indicated that, due to its buffering capacity, the pH of lime stays above pH10 and can be in the region of pH12 until virtually all of the lime
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32 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 29 has converted by oxidation to the carbonate form, when the pH drops rapidly. Exposure of the soils again to the air at the surface, would be anticipated to trigger this reaction and the pH rapidly reduce as a result. It is therefor unlikely to be a hazard to the quality of stormwater run-off from the site. Study of the effect of lime in groundwater at the same site, indicated that the pH was normal within 3 metres of a quarry that was filled with lime waste for more than 50 years and it was concluded that the presence of concentrations of lime remaining on that site were not a risk to the environment or to groundwater. Lime is also not toxic and not a health risk except that large clumps of unreacted lime can cause burns to mucous membranes.
It also appears unlikely that the transitory nature of the groundwater in the fill on Area A would provide sufficient yield for groundwater use. The area and volume of the fill and recharge capacity appears to be somewhat limited and the compaction and addition of stabilising agents to the compacted imported fill would also have reduced permeabilities to very low levels. It therefore could be considered to have insufficient yield for most potential uses. Attempts to develop the groundwater, if any is found within the fill, would also be expected ultimately to intersect water with TDS similar to the original quality from surrounding areas and, possibly, from Victoria Harbour. Therefore, it is considered that Segment C is the most appropriate classification for the fill material if any is used.
Segment C is relevant to maintenance of ecosystems, stock watering, industrial water use, primary contact recreation and building and structures. The only uses unique to Segment B if that has to be considered, is Agricultural Parks and Gardens – ie irrigation use, or potable mineral water.
Coode Island Silt (B Wells)
TDS values within the CIS or FBS generally lie within Segment D of the SEPP. All of the on-site bores that remain on Area A or adjacent areas of Area B, located in CIS post remediation, indicate TDS not less than 13,000mg/L. A few of the off-site bores located in this horizon indicated potentially lower TDS (MW350B, 353B and 415B). However, these remain in soils below unremediated fill outside the site and may be partly influenced by seasonal inflows of rainwater, as they also have a wide range of TDS up to maximums of 25,000mg/L.
Segment D beneficial uses that should be considered include maintenance of ecosystems, industrial water use and buildings and structures.
Yield would also be an issue for the CIS or FBS, generally considered to be aquitards rather than aquifers. Table 5.2 above indicates the results of field tests that confirm the very low vertical permeability and low horizontal permeability of these formations. Although, some more permeable sandy layers could exist within the formations, none were noted on Area A of the site. Therefore, it is considered that insufficient yield should eliminate the CIS/FBS formations from further consideration as aquifers.
Moray Street Gravels (C Wells)
All arithmetic average TDS values for the C Wells lie within Segment D. Segment D beneficial uses include maintenance of ecosystems, industrial water use and buildings and structures.
In this case, the MSG is the only formation beneath the site that should be considered to be a true aquifer as yields can be expected to be good.
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Summary
A summary of the groundwater TDS values in relation to the SEPP segments are presented in Table 5.3 below and an assessment of, and conclusions as to likely beneficial uses of the groundwater are discussed Section 13.5 of this report and summarised in Table 13.6. The locations of the relevant bores are indicated in Figure 3 of this report.
From the Egis study in 1999, it is known that no registered groundwater bores are located within 2.5km of the site except for groundwater monitoring bores. There are therefore no water supply bores on either the Victoria Harbour Precinct area or anywhere down gradient of the site within 2.5km and no existing beneficial uses of water extracted from the MSG or other aquifers. This is consistent with previous reviews of groundwater data undertaken by this Auditor for the Mirvac and Western Link Audits in which only a few shallow bores located in the Port Melbourne Sands were identified at some distance from this site in South Melbourne or Port Melbourne and which would have no hydraulic connection to the gasworks site.
No central database of bores has been made available for reference by Docklands, but monitoring bores located in shallow soils are known to be present on the MAB site to the north beyond Victoria Harbour, and to the south beyond the Yarra River. These also are not in hydraulic connection with the shallow fill soils on the Gasworks site and therefore not relevant to this analysis.
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Table 5.3 Groundwater TDS/pH Ranges & Beneficial Uses Summary Bore pH pH TDS TDS TDS TDS A1 A2 B C D Range Current mg/L mg/L Mg/L mg/L <500 501- 1001- 3501- >1300 Min Max Average Recent 1000 3500 13000 0 Fill Bores MW345A 6.5-7.8 7 4,700 10,000 7,426 4,700 MW350A 6.4-8 6.8 2,000 4,300 3,025 2,200 MW415A 6.6-7.6 7.1 3,000 9,800 4,760 3,900 MW18A 10.9-11.3 10.9 1,100 1,200 1,150 1,100 MW19A Dry MW21A 10.6-11.3 10.6 4,700 4,700 4,700 4,700 CIS/FBS Bores BH44 7.2 7.2 17,000 17,000 - 17,000 MW350B 7-8.2 7.2 3,300 19,000 7,710 5,900 MW353B 6.6-7 6.8 7,100 22,000 10,276 7,100 MW415B 6.8-7.9 7.1 2,200 25,000 6,243 6,100 MW417B 7-7.7 7.3 4,900 27,000 22,095 22,000 MW422B 6.8-7.3 7.2 3,300 23,000 16,220 23,000 MW17B 7.6-7.7 7.7 17,000 19,000 18,000 17,000 MW19B 7.4-7.5 7.5 27,000 30,000 28,500 30,000 MW21B 7.4 7.4 13,000 14,000 12,500 13,000 MW22B 7.3-7.6 7.6 27,000 28,000 27,500 27,000 MSG Bores MW11C 6.6-7.3 6.8 18,000 24,000 21,750 20,000 MW5C 6.7-6.8 6.7 23,000 23,000 - 23,000 MW19C 6.7-7.2 6.7 16,000 19,000 - 19,000 MW350C 6.9-7.9 7 14,000 22,000 19,000 19,000 MW353C 6.8-7.3 7 9,100 28,000 21,365 22,000 MW21C 6.6-6.8 6.6 16,000 19,000 - 19,000 MW422C 6.9-7.5 7.2 640 24,000 16,087 17,000 MW4C 6.5-8.2 6.8 390 27,000 17,854 18,000
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5.5 SITE CHARACTERISTICS
5.5.1 Topography & Drainage
Area A is essentially flat, however a slight cross fall runs east-north-east to west-south-west through the centre of Area A. As such, surface water run-off is expected to be to the north towards Pigott Street and to the south towards North Wharf Road. Stormwater in Pigott Street discharges to the south-west, whilst North Wharf Road stormwater discharges to the north-west. All stormwater in the area is discharged to Victoria Harbour and the Yarra River.
Since the completion of the remediation works in Area A, some minor ponding of stormwater was noted in the north-west portion of Area A, which appeared either to evaporate or infiltrate the fill soils. Docklands have indicated that the contractor will remedy this ponding so that the area sheds water prior to the release of Area A. However, it is expected that development of Area A with buildings roads and stormwater drainage infrastructure, would also rectify this relatively quickly and run-off would then be rapid and directed into the Yarra River, with much reduced levels of infiltration.
5.5.2 Natural Watercourses
The most significant environmental systems in the surrounding area are associated with the adjacent Yarra River and Victoria Harbour water body areas. The Yarra River is located approximately 60m south west of the southern boundary of the site, and Victoria Harbour is located approximately 200m north west of the northern boundary.
A portion of both the Yarra River and Victoria Harbour are expected to intersect the groundwater table that may migrate from the shallow aquifers on the gasworks site. The Yarra River and Victoria Harbour join approximately 900m west of the gasworks site and from their empty into Port Phillip Bay. The area is tidal and falls within the Upper Estuary Zone of Schedule F7 of the SEPP, Waters of Victoria.
5.5.3 Vegetation
At the time of reporting, Area A was denuded of all vegetation and no topsoil or grass had been placed. Some weeds have re-established on the areas of imported soils, but not on the crushed rock.
5.5.4 Buildings
No buildings are present on Area A having all been demolished or removed during the original decommissioning of the site and later during the remediation process, together with all the sub-structures, except the lower sections of piles broken off and left in the ground.
5.5.5 Underground Structures
A large number of underground structures, including the foundations of a number of buildings and the piles that supported them, remained on the site after removal of the superstructures. These were required by the remediation contract to be exposed during excavations undertaken by Docklands and removed together with any associated contamination. No underground structures remain present on Area A at the time of this audit except the remaining portions of the piles.
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The piles relating to former buildings located on-site were removed to the depth of excavation during the remediation works and all drains and conduits were removed up to the boundaries where they were cut-off and blocked with concrete. Locations of piles are presented on Enterra’s Figure 13. This plan should not be used for reference purposes. The locations of each pile were surveyed and the survey coordinates are understood to be available through Docklands Authority for the use of future developers.
5.6 SITE HISTORY
The historical usage of the overall gasworks site has been well documented and summarised in a number of previous reports reviewed by the Auditor, including:
• “Melbourne Docklands Redevelopment Ground Contamination Study, Volume 1”, Camp Scott Furphy Pty Ltd/Golder Associates Pty Ltd (September 1989);
• “Phase II: Investigation of Contamination of the West Melbourne Gasworks Site”, CMPS&F Pty Ltd (January 1994);
• “Environmental Audit Report: Former West Melbourne Gasworks Site”, Sinclair Knight & Partners Pty Ltd (January 1994);
• “West Melbourne Gasworks Draft Site Investigation”, CMPS&F Pty Ltd (April 1995);
• “Docklands Authority Site Characterisation, Victoria Harbour Precinct”, CMPS&F Pty Ltd (February 1997);
• “Former Gasworks Site Partial Site Encapsulation Final Concept Development Report”, Coffey Geosciences Pty Ltd (August 1999); and
• “Remediation of West Melbourne Gasworks Site, Area A Validation Report”, Enterra Joint Venture (September 2001) revised in February 2002.
In the early 1800’s, the area now known as Victoria Harbour Precinct consisted of a swampy flat land of the West Melbourne Swamp. In 1854, the City of Melbourne Gas and Coke Company leased 5 acres of Crown Land (the Site) within this area and established the West Melbourne gasworks facility to supply gas to Melbourne.
The gasworks facility produced gas for residential and industrial power by the gasification of black coal up until 1962 and from then on, the facility was upgraded to incorporate a catalytic oil gas facility. The original site was 2 hectares, however this was expanded to 8 hectares between 1900 and 1910. The West Melbourne Gasworks ceased production in 1970 and remaining structures on-site were subsequently demolished in 1974. The above ground structures were dismantled and removed, whilst a number of buried or sub-surface structures (such as tar pits, gasholder sumps, and other miscellaneous pits and pipelines) were filled or covered and left in place (CMPS&F, 1997).
Since the closure of the gasworks site in 1970, the main historical usages, as indicated from text references (Proudley, 1987) and from a study of the aerial photographs (Coffey, 1999) include the following:
• The 1972 aerial photo shows the southern and south west corner of the gasworks site to be largely cleared open space with a few buildings;
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• In 1974, the site was demolished. All above ground structures including the tall stack and the gasometers and tar tank were demolished to below ground levels. The buried part of the structures, such as the gasometers and tar pits, were backfilled and left in place.
• The 1975 aerial photo shows that most of the former gasworks site has been levelled, with only a few buildings remaining in the north west corner of the site. Works on the alignment of Charles Grimes Bridge Road had commenced. The aerial photos also show clear evidence of a gasholder approximately 10 – 15 m from Blyth Street and a clear imprint of the former tar tank adjacent to Blyth Street is evident.
Information supplied to various parties (including Egis, Coffey’s, Docklands Authority and this Auditor) included extracts from the Melbourne Board of Works contract for the removal of the gasholders to permit construction of the former Charles Grimes Bridge Road which crossed the former gasworks site to the east of the eastern boundary of Area A. Item 4.3.1 of the contract concerned the excavation and cleaning out of rubbish from pits on the site, and their backfilling with suitable material prior to construction of the road. However, no documents were available to indicate that this had taken place.
The approximate location of various structures comprising the former gasworks are also indicated on the site plan Figure 2, based on the information supplied from various sources.
The Site history is also summarised in the Enterra JV 2001/2002 validation report and has also been referenced by the Auditor for this assessment. The gas manufacturing and related industrial processes that occurred on the site, as based on various sources of information, are also discussed in section 5.7 of this report.
5.7 PREVIOUS INDUSTRIAL PROCESSES UNDERTAKEN ON-SITE
The former West Melbourne Gasworks site produced gas from coal carbonisation using black coal from January 1856 until 1962. From 1962 until 7 December 1970 the facility was upgraded to incorporate catalytic oil gas facilities (oil gasification). Summaries of these processes are listed below.
Coal Carbonisation. Coal gas was produced by heating black coal in a closed vessel called a coal- carbonisation retort, until all the volatile materials were removed. The evolved gases were collected and purified prior to use, and the remaining coke was removed from the retort.
Oil-Gas Production. The process of oil-gas production varied at each manufactured gas plant but generally consisted of catalytic cracking and steam reforming of a particular fraction from the distillation of crude oil followed by another catalytic reaction to increase the H2/CO ratio. Carbon and oil were used in the production of oil-gas by the following process:
• A blow with air to burn off carbon;
• Heating with air and oil;
• Steam generation of water gas (often called blue gas);
• Oil and steam generation of a mixture of gaseous hydrocarbons; and
• Steam purging to remove the final product.
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Following on from heat recovery, product gas undergoes a number of clean up steps depending on its final intended use. The most complex clean up requirements were undertaken at coal carbonisation plants, such as the West Melbourne Gasworks. Typically the product gases from coal carbonisation processes contain numerous organic and inorganic compounds. Many of these compounds had to be removed from the gas to ensure proper combustion, and many of the compounds also had potential commercial value. Typical clean up of these gases removed naphthalene, ammonia and light oil prior to a sulphur removal process.
Oil gas typically contains only traces of the many organic compounds, and several of the nitrogen based inorganic compounds. As a result gases formed through this process typically only required removal of trace organics such as naphthalene and sulphur prior to storage and/or distribution.
5.8 BY-PRODUCTS AND WASTES GENERATED
A process diagram showing the raw materials used, by-products and wastes generated in relation to each part of the gas production process at a typical manufactured gas plant is shown as Figure 5.4.
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Figure 5.4 Typical Coal Gas Production Process
Coal Coke GAS PRODUCTION GAS Oils AND HEAT RECOVERY Gas Product Air CLEAN-UP Steam Ammonia Saturator Ammonia Still Liquor Sludge Ash, clinker and Spent Lime coke Aqueous/hydrocarbon condensate Ammonium Lampblack Sulphate Spent Oxide Tar/oil/water TAR/OIL/WATER Liquid Scrubber emulsion SEPARATION Blowdown (nickel/arsenic/iron) Tar decanter sludge Naphthalene
Wastewater Tar / Oil Light Oil Light Oil Ammonium TAR AND Middle Oil Sulphate HYDROCARBON WASTEWATER PROCESSING Heavy Oil Lime/iron REATMENT T Anthracene Oil treatment sludges Pitch Phenol Acid/Caustic Treated Sludges Wastewater Tar / Oil
(Source: Management of Manufactured Gas Plant Sites, Volume 1, Wastes and Chemical of Interest, Gas Research Institute, 1987). A discussion of by-products, residuals and other wastes associated with each of the processes in Figure 5.4 above, is provided below.
5.8.1 Gas Production and Heat Recovery; & Tar/Oil/Water Separation
Feed Stocks
Feedstock utilised in the manufacture of gas consisted of coal, coke and a range of petroleum materials. The petroleum materials were fed either as the primary feedstock or as a carburetion oil to enhance the energy content of the manufactured gas. Carburetion oils at typical manufactured gas plants ranged from commercial oil to naphtha, heavier gas oils and heavy residuum from the gas plant by-products.
Solid Residuals
Coke (the substance remaining after gas has been extracted from coal) is the primary solid residual from the coal carbonisation process. Notwithstanding coke can also be used in the gas manufacturing process. It is generally processed to the point that ash is produced. Ash is also produced in the oil gas process, however this ash resembles a petroleum ash.
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Tars, Oils & Lampblack
Hydrocarbons in the form of tars, oils and lampblack (pigment made from soot) are produced in the manufacture of gas from coal and oil. Coal tars are produced primarily from the initial distillation of raw coal during the coal carbonisation process that occurred in both coke ovens and retorts.
Tar/Oil/Water Emulsions
Hydrocarbons are also condensed from the raw gas produced along with excess steam. The excess steam represents moisture which evolved from the coal or reactant steam which did not form part of the gasification reactions. During the condensation process the solid, aqueous and hydrocarbon phases formed emulsions. These emulsions were often used as fuels providing the water content was not too high. If the water content was high, the emulsion was often used for dust control on roads or managed as a waste. These emulsions were not as common to coal tar processes, rather, they usually appeared in oil gas processes.
Tar Decanter Sludge
During the coal gas process some very heavy hydrocarbons are produced which combine with fine coal or coke solids to form a solid/semi-solid black pitchy sludge which settles in the oil/tar/water separator. This material was typically purged from separators and used for dust control on roads or managed as a waste product. This material was not produced in any significant quantities by the oil gas process.
Aqueous Residuals
Condensation from the gas production process contained nearly all of the hydrocarbons with which it came into contact. Concentrations of these hydrocarbons are limited by their solubility in water. In general these residuals were combined with other process wastewaters and may have been managed in some kind of wastewater treatment unit prior to discharge off-site.
5.8.2 Gas Clean-Up
Hydrocarbon Residuals
Major hydrocarbon residuals from gas clean up works generally comprise light oil, naphthalene and ammonia saturator sludge. Ammonia saturator sludge is only associated with the coal carbonisation process and not the oil gas process. Ammonia saturator sludge is a by-product of the polymerisation of hydrocarbons in an acid scrubber used to recover ammonia from coal carbonisation gas. This material is typically a hard pitch-like material.
Naphthalene and light oil are by-products which could be sold, depending on market availability, or alternatively they could be recycled within the plant as part of the wash oil for use as a producer or carburetion feedstock. Recovered naphthalene typically included methyl and dimethyl derivatives of naphthalene as well as naphthalene itself.
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Inorganic Solid Residuals
Gas clean up often involved the reaction and/or absorption of gas constituents with solids which then produced and inorganic solid residual. The most common of these materials produced were spent lime, spent oxide and ammonium sulphate.
Ammonium Sulphate was a by-product produced directly from the reaction of ammonia in coal gas with sulphuric acid, as such it was only produced during the coal carbonisation process.
Spent lime and oxide (also referred to as purifier box wastes or oxide box wastes) resulted from the use of lime and iron oxide as solid reactants for the removal of sulphur from the product gas. In addition to removing sulphur, these products also remove cyanides from the gases. It is noted that gas-phase cyanide was only a significant by product during coal carbonisation processing.
Aqueous Residuals
During the gas clean up process aqueous residuals consisting predominantly of an ammonia liquor and liquid blowdowns from the aqueous sulphur removal systems. This residual was only produced during the coal carbonisation process. Ammonia liquor was generally processed in the wastewater treatment system.
5.8.3 Wastewater Treatment
Hydrocarbon Residuals
Lime or iron treatment used to form insoluble organic and inorganic precipitates which may have had characteristics similar to coke plant wastewater treatment process sludge. Typically suspended tar, coal particulates and oil and grease were removed in this treatment/separator process. Phenol was another major organic resulting from the wastewater treatment process.
Inorganic Solid Residuals
The major inorganic residual recovered from the wastewater generated at gasworks sites was ammonia. This was typically converted to ammonium sulphate via an on-site reaction with sulphuric acid.
Aqueous Residuals
Typically treated wastewater from gasworks sites was discharged to a local surface water body or the local municipal plant sewer.
5.8.4 Tar/Hydrocarbon Processing
The coal or oil gas tar produced consisted of a range of organics which had a market value if they could be recovered. These by-products consisted of several hydrocarbons with differing boiling point ranges. These hydrocarbons were known as light oil, middle oil, heavy oil, anthracene oil and pitch. In addition to these by-products, some wastes were produced as these hydrocarbons were treated prior to sale. Specifically, many of the tars were treated with acid or caustic as a means of removing either the tar acids or tar bases, and resulted in the production of both acid and caustic hydrocarbon sludges.
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5.9 MONITORING OF SITE CONDITIONS
The Auditor and/or Auditor’s team visited the gasworks site, including Area A over eighty times throughout the duration of the project. Monitoring visits were typically undertaken to assess the overall progress of the works. These visits were also used to verify the presence of historical sub-structure anticipated from the former gasworks operations.
The site was broken up into a number of 10metre grid squares and survey control allowed direct comparison of each grid with the former operations and earlier investigations undertaken in that area, in order to verify conclusions drawn by Enterra from their observations. The grid layout is illustrated in the combined site plan, Enterra’s drawing titled “West Melbourne Gasworks Site, Site Plan Detailing Previous Investigation Data – Boreholes/Test Pits” dated 15/05/2000 provided at the request of the Auditor, and included in Appendix F of this report for reference.
On a number of occasions the Auditor and/or Auditor’s representatives were also asked by Enterra to observe and/or comment on specific issues, and some such visits tended to be focussed on specific areas of the site whilst also allowing monitoring of general activities in progress.
The Auditor also requested to be informed when works were being carried out in areas of potentially significant residual contamination as based on the site history, to provide an opportunity to gain a visual understanding of these areas before any backfilling activities commenced. A number of unannounced visits were also paid to the site to review working methods and the level of supervision being provided by qualified staff, or to follow up on concerns that were identified at earlier visits.
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6. BENEFICIAL USES OF THE SITE
6.1 ASSESSMENT OF BENEFICIAL USES
The issue of a Certificate of Audit requires the Auditor to be satisfied that the environmental condition of the land at the site is neither detrimental nor potentially detrimental to any beneficial use of the land.
“Beneficial use” means a use of the environment or any element or segment of the environment which: a) is conducive to public benefit, welfare, safety, health or aesthetic enjoyment and which requires protection from the effects of waste discharges, emissions or deposits or of the emission of noise; or b) is declared to State environment protection policy to be a beneficial use.
In determining the environmental condition of the subject site, the Auditor took into account the following beneficial uses of the land at the site:
• the life, health and well-being of humans both on the site and external to the site;
• the life, health and well-being of other forms of life, including relevant flora and fauna, both on and external to the site;
• impact on surface waters and groundwater;
• impact on the ecology, and the production of food, on or immediately contiguous with the site; and
• the protection of buildings and structures with regard to corrosion, chemical degradation, fire or explosion risk related to contamination.
Where the land at a site is contaminated to a level which precludes the protection of a beneficial use listed above, the Auditor is prevented from issuing a Certificate of Audit, and will conclude that a state of pollution exists. In this event, the Auditor will direct that the land must be:
• cleaned up to a level where the contamination does not preclude protection of any beneficial use or the beneficial uses designated by the Auditor; or
• managed to a level where the contamination does not preclude protection of the beneficial uses designated by the Auditor.
6.2 PREVIOUS BENEFICIAL USES
The following beneficial uses of the site (post- use as a gasworks) have included:
• human health (associated with commercial/industrial uses i.e. non-residential related to mostly informal storage - non-load bearing); and
• use as open space and for commercial industrial purposes.
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Specifically the segments of the environment have included commercial/industrial use as an informal storage area for demolition materials for the last 10-20 years with probable use of the adjacent buildings as additional storage and office.
6.3 PROPOSED OR POSSIBLE BENEFICIAL USES
The proposed beneficial uses indicated by Docklands for the segment represented by Area A, is for the following:
• High density residential use, specifically related to construction of multi-storey apartment buildings with associated access roads, landscaped areas and other facilities (buildings).
• Open Space, specifically general (or passive) non-recreational open space use associated with public park areas, waterfront pathways, road infrastructure, car parking etc
• Commercial Use, envisioned primarily as retail activities, restaurants, office space or similar activities consistent with a major new suburb in a harbour setting.
No low density residential or other sensitive uses are proposed, and no industrial use, although this last would be feasible in the same terms as for Commercial use.
6.4 RELEVANT ELEMENTS
An element of the environment is any of the principal constituent parts of the environment including water, atmosphere, land, vegetation, climate, sound, odour, aesthetics, fish and wildlife.
For the former West Melbourne Gasworks site, relevant elements are considered to be the following;
• Surface waters on the site, runoff from the site and receiving waters;
• Groundwaters beneath the surface of the site and down-hydraulic gradient of the site;
• Land on the site;
• Atmosphere and odour at the site and within any proposed buildings at the site;
• Terrestrial flora and fauna, on the near the site; and
• Aesthetics of land and water elements on and near the site, including recreational use of the adjacent water bodies.
On this basis, the above elements are considered relevant and therefore part of the relevant segment for the purposes of the environmental audit.
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7. POSSIBLE SOURCES OF CONTAMINATION
7.1 ON-SITE SOURCES
Section 5 of this report contain details on former industrial processes and waste generation activities undertaken during the operation of the gasworks.
Table 7.1 summarises the more significant activities that are considered to have been potential on-site sources of contamination, and of the associated potential contaminants resulting from these operations, particularly those that relate specifically to Area A of the site.
Table 7.1 On-Site Sources Of Potential Contamination
Site Activity/Use Potential Contaminants Comment
Oil Gas Plant and Retort House Commonly PAHs, metals petroleum Considered likely to be operations including purifiers, waste hydrocarbons (fuels, lubricants and by- present, although water treatment, and waste disposal and products), solvents, and pesticides. probably confined to land filling on site with ash and tarry Including in the wastes also cyanides, the filled profile with contaminated wastes. phenols, ammonia, and sulphates. some infiltration into Potentially asbestos from building underlying Coode materials, although no evidence was Island Silt. noted of this on Area A.
Coke Storage PAHs
Coal Handling PAHs
Boiler House Operations TPHs, PAHs metals
Former Transport Operations TPHs, PAHs
Presence of underground storage tanks TPH/BTEX, lead Considered most likely (two identified at cell L25 and one at associated with fill N17) material, to top of CIS.
The approximate locations of the significant former gasworks structures are shown on Figure 2 and in the Enterra drawing included in Appendix F, and in detail in the historical plans included by Enterra in their Figures 3A to 3G.
7.2 OFF-SITE SOURCES
Potential off-site sources of contamination have been identified potentially upgradient from the site include the following areas.
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• Former underground structures including gasholders, tar pits, oil storage tanks, and other gasworks infrastructure including the retort houses and ammonia plant, all located within the overall former West Melbourne Gasworks site to the east of Area A in Area B of the site.
• The Gas Regulation Station (GRS) immediately west of Blyth Street (also included as part of the Clean Up Notice issued by the EPA).
• The Queen’s Warehouse site, located to the east of Blyth Street. This was built in 1890 and used to store confiscated, confidential and bonded goods. It is understood that it has also been used for bank note and stamp printing operations as well as storage of general goods.
• The area to the south of the Queen’s Warehouse building was occupied by Australian Quarantine & Inspection Service (AQUIS) from approximately 1961 until the present day. Fumigation chemical storage and treatment are understood to have taken place on this site.
• A service station was formerly located on the property located between the Queen’s warehouse and the former Footscray Road reserve. It is understood that this operated from 1952 until at least 1973.
• Trinidad Asphalt that also occupied the site to the north of Queen’s warehouse since the 1920s and that also contained USTs and processed tar by-products from the gas plant.
• The Spencer Street Railyards, located to the east of Wurundjeri Way.
• The areas immediately to the north, west and south of the boundaries of Area A also include areas historically potentially occupied by the former gasworks activities during early years of operation prior to formalisation of the current boundaries. This includes coal handling operations; cement loading and unloading; other wharf activities along the Yarra River frontage and in Victoria Harbour; and an area of hardstanding on the north side of Piggot Street that was used for car storage and delivery.
Given the variable groundwater flow directions indicated prior to remedial works (including flows to the east and south-east), during the remedial works and as indicated by the results of the monthly groundwater sampling performed for the duration of the remediation contract, it is considered that there is potential for impacts from these sources depending on the aquifers considered and local flow regimes. These potential sources have therefore been taken into account in the assessment and remediation program.
The groundwater modelling and risk assessment undertaken by the Auditor also considered the potential impact of migration of groundwater from the areas indicated above into Area A of the site. In particular, the potential for pollution of the groundwater beneath Area A from these areas was considered if the groundwater flow regime reverted to a north westerly, westerly or south westerly flow after recovery of the shallow water table.
7.3 CONTAMINANTS OF CONCERN
The contaminants associated with the gasworks operations and processes both on Area A and on the adjacent areas of gasworks and other operations detailed in Sections 5 to 7 of this report, are summarised in Table 7.2 below.
Table 7.2
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Typical Contaminants found at Gasworks Sites Inorganics Metals Volatile Phenolics PAHs Aromatics ammonia Aluminium Benzene phenol Acenaphthene cyanide Antimony Ethylbenzene 2-methylphenol1 Acenaphthylene nitrate Arsenic Toluene 4-methylphenol1 Anthracene 2 sulphate Barium total xylenes 2,4-dimethylphenol benz(a)anthracene sulphide Cadmium benzo(a)pyrene thiocyanates Chromium benzo(b)fluoranthene Copper benzo(g,h,i)perylene Iron benzo(k)fluoranthene Lead chrysene Manganese dibenz(a,h)anthracene Mercury dibenzo furan Nickel fluoranthene Selenium fluorene Silver fluorene Vanadium naphthalene Zinc phenanthrene pyrene 2-methylnaphthalene 1 methylphenol is synonymous with cresol 2 2,4-dimethylphenol is synonymous with 2,4 xylenol (Source: Management of Manufactured Gas Plant Sites, Volume 1, Wastes and Chemical of Interest, Gas Research Institute, 1987):
Although the above list is extensive, it was acknowledged by the Auditor during the many phases of investigation and risk analysis that took place, that many of the potential contaminants anticipated to be on the site were present at quite modest concentrations and of limited significance, whilst a number of key contaminants were present at significant concentrations. The remediation plans were therefore generally based on remediation of the key contaminants of concern, as that was anticipated also to remove concentrations of other contaminants that may have been present. This is discussed further below.
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8. ASSESSMENT GUIDELINES
8.1 PURPOSE OF GUIDELINES USED FOR ASSESSMENT
This section discusses soil and groundwater guidelines that have been used by the Auditor in the initial screening level assessment of contamination detected in soil and/or groundwater at the site. These guidelines are considered to be appropriate with respect to screening level assessment in Victoria and South Australia.
The purpose of the guidelines is to provide a basis whereby the data for a given site may be screened to identify conditions that may warrant further consideration with respect to risks to human health or the environment and therefore the requirement to undertake remediation or other site management. The guidelines do not represent values above which remedial action would be required either within a regulatory context or for the protection of human health or the environment. Rather, these guideline values provide an appropriate basis for identifying conditions that do not warrant any further consideration.
Where further consideration is indicated by exceedence of these guidelines, this has been provided by qualitative and quantitative risk assessments developed by others on behalf of Docklands Authority, or by the Auditor, to establish appropriate target criteria for the site.
The following sections summarise the sources of assessment guidelines for soil and groundwater used by the Auditor.
8.2 ANZECC ASSESSMENT GUIDELINES
The Australian and New Zealand Environment and Conservation Council (ANZECC), the National Health and Medical Research Council (NHMRC) and the Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ) have issued the following publications relevant to the assessment of environmental risks on the site.
• “Australian and New Zealand Guidelines for the Assessment and Management of Contaminated Sites” (ANZECC/NHMRC, 1992) – the ANZECC Guidelines.
• “Australian Water Quality Guidelines for Fresh and Marine Waters” (ANZECC, 1992)
• “Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC/ARMCANZ, 2000)
The “ANZECC Guidelines” in Victoria continue to be the sole formally recognised guidelines for the assessment and management of contaminated land (pending finalisation of the State Environmental Protection Policy for Land), although the National Environmental Protection Measure “Assessment of Site Contamination” of December 199, is also recognised by Victoria where these supplement or supersede the 1992 guidelines.
The ANZECC Guidelines outline an approach to the assessment, management and remediation of contaminated land and includes typical background concentrations (A levels) for a range of common contaminants and threshold concentrations for some contaminants (B Levels) above which further investigation of a site should be considered for the protection of the environment.
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Where investigation guidelines were not nominated in the ANZECC guidelines, reference is also made to the Dutch investigation level guidelines (1985) for environmental concerns. ANZECC recognises that the revised Dutch 2000 guidelines are conservative and have been principally set for the protection of groundwater.
The ANZECC environmental investigation criteria have been determined on the basis of current toxicological data and are considered to be conservative. These are interim criteria based on threshold levels for:
• phtyotoxicity; and
• uptake of contaminants which may result in impairment of plant growth or reproduction or unacceptable residue levels.
In general the investigation levels are considered to protect the most sensitive receptors. Where the levels of chemicals in soils are below ANZECC and Dutch investigation guidelines, the condition of the land is considered to satisfy the requirements of the protection of all beneficial uses (with the possible exception of groundwater quality).
The ANZECC guidelines provide a basis for the further investigation of contamination for a range of chemicals and, where exceeded, a risk-based review of the potential impact from environmental exposure for sensitive land uses is considered appropriate.
It is noted that Enterra have not, in the first instance, compared results for the validation works to ANZECC B thhreshold investigation levels, as target criteria were set for the site by the Docklands Authority based on earlier investigations and risk assessments that had already developed acceptance criteria for inclusion in the remediation contract. This is discussed in further detail in Section 13 of this report.
8.3 NEPM HEALTH INVESTIGATION GUIDELINES
The ANZECC guidelines do not provide thresholds for varying land uses. Therefore, for the purposes of establishing screening levels, the following guideline documents have been adopted for screening purposes for varying land use.
The National Environment Protection Measure “Assessment of Site Contamination” (NEPM, Dec 1999) provides risk-based Health Investigation Levels (HIL) for selected organic and inorganic chemicals. These levels are provided for a variety of exposure settings including residential and commercial/industrial land uses and do not necessarily take into account environmental concerns.
The NEPM Health-based Investigation Levels (HILs) have been developed to be protective of human health and are based on an assessment of potential exposure via ingestion of soil and dermal contact. The various investigation levels have been defined (in summary) as:
• Level A: standard (single) level residential (including child-care facilities);
• Level D: high rise residential land use (including high-rise apartments and flats);
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• Level E: recreational land use (including secondary schools); and
• Level F: commercial/industrial land use.
The Level A guideline would be appropriate for a screening level assessment for residential use, provided it is supplemented by reference to appropriate environmental criteria (flora, fauna and ecological values). Level A criteria are based on conservative assumptions to protect a young child living on the site. This exposure setting can also be applied to daycare centres, kindergartens, preschools and primary schools to provide protection to young children from soil contaminants. Levels D, E and F apply where there is reduced access to soil, or reduced time in the setting for young children. The Level F guideline is appropriate for the assessment of on going industrial use.
It should be noted that the NEPM guidelines do not provide an exhaustive list of potential contaminants and reliance on other guidelines or risk analysis is also necessary.
8.4 NEPM ECOLOGICAL INVESTIGATION GUIDELINES
As an interim measure, the NEPM (Dec 1999) provided ecologically-based investigation levels (EILs) for an urban setting based on considerations of phytotoxicity and soil survey data, whilst retaining several ANZECC B values where appropriate.
8.5 STATUS OF GROUNDWATER IN AN AUDIT
The now superseded 1998 EPA guideline on contaminated land auditing provided assistance to auditors in assessing whether groundwater is an “other relevant element” of the environment and therefore part of the “site” (the relevant segment of the environment) referred to in the Certificate or Statement of Environmental Audit. Therefore, although groundwater is always required to be considered in an environmental audit (“total assessment of the environment”), it may be assessed as “not relevant” to the site for the purposes of an environmental audit and therefore not a restriction to issuing a Certificate or Statement of Audit.
Where pollution of groundwater exists, however, and derives from the site such as to impact upon any adjacent element of the environment, a restriction on use of the site may exist and a Certificate may not be issued.
These principles have been incorporated into Section 13 of the updated May 2001 Auditor Guidelines.
8.6 GROUNDWATER POLICY AND GUIDELINES
The State Environmental Protection Policy ‘Groundwaters of Victoria’ (EPAV, 1997) (Groundwater SEPP) governs groundwater management in terms of contamination issues in Victoria. The Groundwater SEPP defines segments of the groundwater environment on a salinity basis with beneficial uses (ie potable supply, maintenance of ecosystems etc) assigned to each segment.
Based on the protection of beneficial use of the water, the Groundwater SEPP in most cases directs use of ‘The Australian Water Quality Guidelines for Fresh and Marine Waters’ (ANZECC, 1992). This provides the basis for assessment of beneficial uses of the groundwater such as for drinking purposes, stockwatering
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51 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 48 etc. The ANZECC/ARMCANZ 2000 Guidelines however have included consideration of ecosystem protection for fresh and marine waters based on protection of a range of between 80% and 99% of species. The Groundwater SEPP also directs use of SEPPs relevant to surface receiving waters with regards to ecosystem protection.
It should be noted that the referenced ANZECC water quality guidelines and the SEPP “Waters of Victoria” are applicable to protection of receiving waters and not to groundwater. However, they form an appropriate basis for undertaking a screening level assessment beyond which the potential impact on receiving waters needs to be assessed. It must also be noted that the SEPP directs the use of the ANZECC 1992 guidelines for indicators not included in the SEPP. The EPA is yet to endorse the use of the ANZECC/ARMCANZ 2000 guidelines in their place.
The selection of the applicable guideline value will be based on the following:
• an assessment of potential pathways by which human or environmental exposure might take place;
• any attenuation which may occur along that pathway; and
• the beneficial end use of the groundwater determined initially by salinity.
8.7 SITE SPECIFIC CLEAN UP CRITERIA
The early investigations of the site (CMPS&F 1994 to 1996, Egis 1997 to 1999, Golder et al 1997) were reviewed by the Auditor on his appointment in 1998 and subsequently during the remediation program. These reviews, together with direct observation during the sampling process, confirmed that the site, including Area A, was heavily contaminated with a range of mainly organic contaminants that could be attributed to the former operation of the gasworks. This confirmed the conclusions of the 1994 assessment and audit undertaken by Mr Rick Graham (discussed in Section 9 below) and also the issue of a Clean up Notice by the EPA.
It was decided by the Docklands Authority to employ Egis (formerly known as CMPS&F) to undertake a risk assessment to determine appropriate soil clean up criteria for the site. The objectives of the risk assessment were discussed with the Auditor and the methodology reviewed during late 1998 after the appointment of the Auditor. The Auditor commented on the process during the period October to December 1998 and on the final risk assessment presented to the Auditor in February 1999. These comments are referenced in Section 10 of this report.
The process undertaken by Egis was a two stage process involved the establishment of “Tier 1” criteria for each of the contaminants of potential concern (COPCs) suspected to be on the site from the history of the land or as identified in earlier investigations. The second stage was the development of a number of “Tier 2” criteria based on a site specific risk assessment and summarised in Tables ES 1 to ES6 in the Egis report titled “Site Specific Clean-up Criteria for the Former West Melbourne Gasworks Site and the Victoria Harbour Precinct” dated December 1998. Tables ES4 to 6 in the report referenced the remainder of the Victoria Harbour Precinct outside the gasworks site.
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The risk based criteria recommended in the Egis risk assessment were not entirely accepted by the Auditor as being suitable for remediation on the site due to factors not fully considered by the risk assessment such as aesthetic issues. The report also did not fully consider all potential impacts on or by the groundwater. The potential ecological risks were limited to a back analysis of the maximum concentrations of chemicals in the soils that would be anticipated to result in acceptable concentrations in the groundwater at the interface with the nearest receptors (in Victoria Harbour or the Yarra River) after moderation by natural attenuation over the distance to those receiving waters.
In some cases the soil concentrations so calculated, although possibly acceptable in terms of human health or protection of ecosystems, could in some instances give rise to significant odours, particularly if re- excavated at a later development stage. The final soil acceptance criteria (the so-called D1, D2 and D3 criteria) incorporated into the contract prepared by Egis for the remediation phase, were therefore requested by the Auditor to be modified in some respects to take account of such concerns. These criteria are summarised in Appendix D of this report.
It was also acknowledged that the groundwater would also remain contaminated to some degree and would therefore potentially have restrictions on potential beneficial uses and require on-going monitoring.
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9. REVIEW OF PREVIOUS ASSESSMENTS
9.1 INTRODUCTION
From 1989 until September 2001 several environmental site assessments were undertaken on the former West Melbourne Gasworks Site for various purposes, but mainly aimed at providing a clearer understanding of the extent and depth of contamination in the soils and groundwater beneath the site.
In August 1993 Rick Graham of Sinclair Knight & Partners Pty Ltd was engaged to conduct an environmental audit of the overall West Melbourne Gasworks site. The findings of this report were based on the available relevant reports at that time (issued between 1989 and 1993) and were presented in an environmental audit report dated January 1994. The audit report is presented in Appendix B of the Enterra Area A Validation Report as file 0075.tif.
The outcome of the 1993/4 environmental audit was the refusal to issue a Certificate of Audit for the site and issue of a Statement of Audit indicating that extensive contamination was present and the site was also a potential source of pollution to nearby water bodies. This resulted in issue of an EPA Clean Up Notice in August 1994 (presented as file 028.tif in Appendix B of the Enterra Area A Validation Report).
For the purposes of this (2002) environmental audit, the 1993 environmental audit, and the most pertinent site assessments undertaken in relation to the condition of the gasworks site, have been reviewed. No additional review of the quality of the documentation referenced by Rick Graham was undertaken as this was fully reviewed by an EPA accredited auditor and discussed in the 1994 audit report.
9.2 SUMMARY OF PREVIOUS ASSESSMENTS
9.2.1 Environmental Audit Report (1993)
On August 17 1993, the Dockland Authority engaged Mr R. A. Graham under the relevant section of the Environment Protection Act (1970), to conduct an environmental audit of the former West Melbourne Gasworks Site. The area subject to the audit was bounded by Pigott Street to the north, the Webb Dock Rail Line tot he east and North Wharf Road to the south.
Mr Graham reviewed all the available previous site contamination assessments and concluded that there was insufficient data available to provide a detailed understanding of the contamination distribution. Mr Graham recommended that further testing would be required to support a detailed remediation plan. Mr Graham noted that PAHs were identified as the contaminants controlling the risk and that the major exposure pathway for all potential land uses was by ingestion of contaminated soil by children. Mr Graham also considered that less than 10% of the site in its present condition was suitable for any type of residential or open space use and only 40% of the site was suitable for commercial use without remediation.
The audit report concluded that the site was not suitable for redevelopment without extensive remediation. The review of the available data also indicated that ammonia was a significant contaminant of potential concern (COPC) in the groundwater.
Two potential remedial outcomes for the site were identified as:
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54 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 51 a) a full clean-up involving excavation and off-site disposal of contaminated soil, or b) a combination of an engineered capping system and a long-term management system.
Mr Graham recommended that further work be conducted directed towards the remediation and redevelopment of the site. On the basis of his assessment, it was concluded that a Certificate of Environmental Audit could not be issued. A Statement of Environmental Audit was therefore issued indicating “…that I (Rick Graham) am of the opinion that the condition of the land at the site is detrimental or potentially detrimental to beneficial uses of the land at the site. Accordingly, I refuse to issue a Certificate of Environmental Audit for the site.”
9.2.2 Soil and Groundwater Contamination Assessment (1997)
In 1997, a contamination assessment of the land at the Victoria Harbour Park Precinct was undertaken by Golder Associates Pty Ltd (Golder), and CH2M Hill Australia Pty Ltd (CH2M Hill). The assessment was undertaken on the behalf of the Docklands Authority and the two bidders for the Precinct, Victoria Harbour Corporation and Yarracity Consortium, in order to establish a basis for the cost estimates for remedial works associated with the redevelopment proposals.
Golder and CH2M Hill were then the consultants for the two bidders competing for the development and the work was directed by Mr Richard Wolf of CH2M Hill who, together with Golder, prepared the report. Due to the size of the project, some assistance with field staff was also provided by AGC Woodward- Clyde Pty Ltd (WWC) under the direction of CH2M Hill.
This assessment included the Gasworks portion of the Precinct. However, as the Precinct only extended up to Charles Grimes Bridge Road, the areas of the gasworks site under, and to the east of Charles Grimes Bridge Road, were not included in these investigations. The area of the gasworks site covered by this Audit (Area A), did however fall within the investigated area.
Design and Scope of Assessment
The 1997 assessment involved the following:
• a review of existing available data on soil and groundwater contamination;
• preparation of a work plan detailing the proposed investigation works and sampling and analysis strategy;
• preparation of a Health and Safety Plan to be adopted during site investigation works;
• collection and chemical analyses of soil (fill and natural soil), groundwater and sediment samples from the site; and
• preparation of a factual report on the findings of the further investigation.
This report was reviewed by this Auditor as part of this audit in terms of the extent and appropriateness of the investigations undertaken, the frequency of the sampling and analyses undertaken, and the quality assurance undertaken on the site and in the laboratory testing to ensure adequate data quality objectives were met.
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The frequency of sampling was limited to a variable grid of between about 30 and 60 metres spacing across the Victoria Harbour Site. The frequency of sampling did not meet with the recommendations of Australian Standard AS4482.1, but was considered acceptable as a basis to allow estimation of the extent of remediation required.
The work plan included the implementation of a quality assurance program that complied with the recommendations in AS4482.1 in terms of the frequency of analysis of laboratory and field split samples, and the results of this analysis was considered to be within acceptable limits to allow reliance on the results for planning purposes. It is considered that the sampling and analytical program were undertaken at an acceptable standard. It was noted at the time that the test results were only provided in a tabulated form, therefore allowing only limited opportunity to check the precision of data transfer.
As much of the data is also relevant to soils eventually removed from the site, this now has limited application to the final condition of the land, so is not reviewed further in detail in this report. This data has not been incorporated into Enterra’s summary of data relevant to the final condition of the site. However, the data relevant to underlying natural soils was referenced by the audit team when considering the depth of clean up implemented by EnterraJV to ensure that pockets or lenses of contaminated soils had not been overlooked in the remediation process. Similarly, the groundwater investgations were superseded by the more extensive Egis investigation of 1999 and subsequent monitoring by Enterra during the remediation program.
The report on the Golder/CH2M Hill investigation is included with the documentation provided by Enterra on CD, and is attached to this audit report for reference. It is titled “Assessment of Soil and Groundwater Contamination at Victoria Harbour Precinct, Melbourne Docklands” prepared by Golder Associates, Woodward-Clyde and CH2M HILL dated December 1997.
9.2.3 Groundwater Investigations (Egis 1999)
The previous investigations were considered to be limited with regard to assessment of the status of groundwater beneath the Victoria Harbour precinct, and the gasworks in particular. Additional groundwater investigations were undertaken by Egis in 1999 at the request of the Auditor as insufficient information was available regarding the status of the various aquifers that were located beneath the site, in particular the Moray Street Gravel aquifer (MSG).
The MSG aquifer was known to be present beneath the site and the Auditor was concerned that it could provide a potential pathway for migration off-site of chemicals detected within the heavily contaminated fill soils and structures on the site. The results of this assessment are discussed in Section 10.2 of this report.
9.2.4 Proposed Encapsulation of Charles Grimes Bridge Road (Coffey, 1999)
This section discusses the considerations undertaken by the Auditor on alternative methods for the remediation by encapsulation of part of the former West Melbourne Gasworks site (Area B) to minimise excavation of contaminated material in an area proposed for a non-sensitive use as public open space. It is
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The proposed encapsulation included review of potential issues with retention of a large body of contaminated soils within the former gasworks site in relation to proposed beneficial uses (including public parks and minor commercial operations including proposed public facilities and a restaurant. It also included discussions between EPA and the Auditor on the implications and possible risks attached to implementation of the proposed containment system, and the presentation of reasoning as to why such a system may have been acceptable to the Auditor. These comments were based on the studies completed by Golder et al and Egis up to the end of 1998, including the risk assessment, and were communicated to the EPA at a meeting on 12 May 1999 and as confirmed in the Auditor’s letter of 21 May 1999 to the Authority.
As discussed at the meeting with the Authority, the Auditor was seeking confirmation that the interpretation of EPA policy and guidelines in relation to groundwater issues at the site was in accordance with the objectives of the EPA, to confirm the acceptability of the containment strategy proposed by Docklands prior to the finalisation of contracts for the remediation of the site.
The Auditor’s understanding and interpretation of the information presented by the Docklands Authority and its consultants regarding the soil and groundwater quality and proposed remediation options at the time of the discussion was as follows:
The two main aquifers of concern were a local upper unconfined aquifer within fill materials overlying Coode Island Silt, and a lower aquifer at about 20 metres depth within the granular Moray Street Gravels
The water quality in the deeper Moray Street Gravel Aquifer was saline (TDS 19,000 to 38,000 mg/L) and of limited beneficial use in terms of the SEPP on groundwater except in terms of the requirement for maintenance of ecosystems or potentially industrial use.
The geological model indicated that no hydraulic connection between the deep aquifer and marine or estuarine ecosystems in the Yarra Delta had been previously found within the many boreholes located in the area. This included within the Yarra River channel, and a connection appeared unlikely to exist within a relatively short distance of the site.
Gradients within the deeper aquifer were indicated to be relatively low, and flow rates, as predicted by Dockland’s consultants, modest even in a worst case scenario.
The only contamination at that time detected in the deeper aquifer was located centrally within the existing Footscray Road (Charles Grimes Bridge Road) corridor across the site and appeared related to potential source areas within the former gasworks (Area B of the site)
The more mobile contaminants such as benzene, petroleum hydrocarbons, and phenols, had at that time not reached the most southerly borehole, over 100 metres from the southern site boundary (the Yarra River), although this appeared to be the most likely flow direction as predicted by Docklands consultants. Other less mobile contaminants including mainly PAHs, were more localised in the central area.
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Ammonia was present in modest concentrations throughout all the bores up and down gradient on and outside the site and did not appear to be necessarily related to the Gasworks Site itself.
In a saline environment, diffusion was also considered to be more important in contaminant migration than advective flow transport and therefore migration rates were likely to be slower than the theoretical rates based on potential groundwater flow.
At that time (mid 1999), the Docklands Authority proposed to remediate the contaminated soils to the west and east of Footscray Road envelope to include removal of the top sections of former piles penetrating the underlying Coode Island Silt and sealing the cavity to prevent future potential vertical migration. They also proposed to construct a containment wall with a minimum 100 year design life around the road corridor to contain the remaining contaminated soils and contaminated shallow groundwater. As far as was practicable, the Docklands Authority also proposed to remove potential sources of contaminants contained within structures buried beneath the road within the containment area.
Although there remained some gaps in the available information which the Auditor requested to be filled, in that there was insufficient data on contaminants remaining inside and outside the known gasworks structures including former gasholders and tar pits, it was considered at the time that much of the information available was positive with regard to the alternative containment being proposed by Docklands and their contractors.
The Auditor was of the opinion that, providing the sources that remained within the containment area were adequately contained or else removed, then allowing for diffusion and attenuation over the likely distances to potential receptors, the contamination that had already reached the MSG as indicated by the Egis investigations, and may also reach it in the future, was not likely to migrate at a sufficient concentration or with sufficient rapidity, to be a risk to existing ecosystem receptors within the medium term. It was anticipated that a suitable risk assessment would also confirm that discharges exceeding policy objectives to surface water from the deep aquifer were unlikely in the long term. (A risk assessment was subsequently undertaken by the Auditor following removal of the main sources of contamination and confirmed the 1999 opinion).
In formulating these opinions, it was also noted that the containment option called for a capping layer which would assist the situation by limiting infiltration of rainwater which in turn would minimise the potential to drive groundwater flow deeper through the contained contaminated soils and into the underlying aquifers and minimise potential for later contact with the affected soils.
In these circumstances, where the site had been cleaned to the extent practicable, the Auditor believed that, as the contaminated groundwater was unlikely to impact on an existing or likely beneficial use, it would have been acceptable for the Auditor to issue a Statement of Audit for the contained portion of the site where uses of the land are limited to that of a transport and utilities corridor and passive open space.
The Statement of Audit would have included conditions indicating that groundwater abstraction should not be recommended, and would require on-going management of the groundwater to include long term monitoring at the boundaries of the containment as a minimum, together with a management plan to be implemented if conditions changed, such that an environmental risk could develop over time.
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In a worst case scenario, it was also the Auditor’s opinion that, if monitoring bores were installed around the containment after construction and indicated that contaminants were potentially migrating off site to a receptor, a groundwater management program could be instituted in the proposed parkland area created over the containment, to reverse hydraulic gradients to create an inward rather than outward flow.
The above opinions were accepted in principle by the EPA in their letter to the Auditor of 9 June 1999 provided that appropriate monitoring and a management plan was instituted that would be activated if conditions changed such that environmental risks developed over time.
In pursuing this option, Coffey Geosciences Pty Ltd (Coffey) were commissioned by Enterra (a joint venture between Abigroup Contractors Pty Ltd and IT Environmental Australia Pty Ltd) to design an encapsulation system for the on-site containment of contaminated soil. This included a study by Coffey Partners that was the basis of their design considerations. The Auditor reviewed this document titled: “Draft Technical Brief – Encapsulation of Charles Grimes Bridge Road, Interim Geotechnical Design Report”reference Coffey Geosciences Pty Ltd Ref E13635/2-DC dated 5 November 1999.
The following general and specific comments on the Coffey document were presented to Docklands by the Auditor with regard to the audit objectives on the former West Melbourne Gasworks site:
The documentation provided by Coffey indicated that further investigations were necessary before a design could be finalised.
The Auditor expected that the overall performance objective of the encapsulation approach was to contain existing contamination to such an extent that migration of these contaminants into the surrounding environment was limited for a period of at least 50 years without significant pumping requirements to lower water levels. (Site characterisation completed at the time of the report suggested the presence, within the Charles Grimes Bridge Road area (the containment area), of relict gas holders and other subsurface structures, as well as tarry free product (and associated NAPLs and DNAPLs) and zones of elevated soil and groundwater contamination. It was considered that these all represented potential sources of pollution and contamination of the surrounding environment that should be removed or contained.
It was anticipated at the time of the 1999 Coffey report that Area A, to the west of the proposed containment area, was to be remediated to soil clean-up criteria that were developed for the intended high density or commercial developments in that area. This remediation was expected to also lead to an improvement of existing groundwater quality in Area A, as dewatering activity would result in the removal of some shallow contaminated groundwater. On this basis the Auditor expected that the encapsulation approach for the Charles Grimes Bridge Road area should contain the contaminants such that they would not impact, for at least 50 years, on the post- remediation environmental quality of Area A, on the other areas surrounding the proposed containment wall, and on Victoria Harbour or the Yarra River.
The Auditor was unable to accept the proposals put forward by Enterra in the Coffey document as they indicated a maximum life of the proposed containment structure of only 8 years which did not meet with the remediation objectives. There was also no guarantee that the potential sources of
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continuing contamination to the groundwater beneath the site (the deep gasholders and tar pits) would be effectively removed or moderated.
As there appeared to be minimal net environmental benefit from the proposals put forward by Enterra, the Docklands Authority ultimately did not accept Enterra’s proposal and required full remediation of the park area to be undertaken. Full remediation of this area therefore subsequently took place, but much of the information provided in the investigation of this option was useful in monitoring the effectiveness of the remediation, particularly in regard to the removal of sources of contamination located in the gasholders and tar pits that may have remained sources of pollution into Area A of the site.
9.3 COMTECHPORT FILL
As part of the audit of the gasworks site, a report was provided to the Auditor titled “North South Road Stockpile Sampling Program Environment Assessment Report” Volumes 1-3, Prepared by Egis Consulting Australia Pt Ltd, August 2000. This report includes the results of the analysis of 800 samples at a 1 in 100m3 frequency that demonstrates the quality of soils stockpiled by Docklands on the precinct to the north of Colonial Stadium.
As the Auditor of part of the Docklands Infrastructure Developments as well as the Auditor of the West Melbourne Gasworks site where it was intended that the soils eventually be re-used, it was requested by this Auditor that this sampling be undertaken and was monitored as part of the audit. Egis managed the sampling and identified any material that exceeded “Low Level Contaminated Soil” criteria which was then removed by Maunsells.
Ultimately, some 69,000m3 of material from Comtechport meeting the D1 criteria for backfill material, was re-used on the Gasworks site including a substantial proportion on Area A. About 50,000m3 was re- used as “D1” classified material and the remainder being used in place of “D3”.
The documentation was reviewed by this Auditor for accuracy and compliance with AS Standards regarding QA for the laboratory analyses. The tracking of the movements of the stockpile were also monitored and the survey reports reviewed by the Auditor. It is considered that the data contained in the Egis report is sufficient and is representative of the material that was ultimately delivered to the site by Kingston Plant Hire on behalf of the Docklands Authority. The recovery, sorting, removal of any dumped foreign material identified visually or from the survey of the stockpiles, the screening to remove any remaining aesthetically objectionable material, and the final delivery of the fill material, was all managed by GHD on behalf of Docklands.
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10. DERIVATION OF SITE SPECIFIC CLEAN-UP CRITERIA
CMPS&F Pty Ltd (later known as Egis Consulting) was commissioned by the Dockland Authority to undertake the development of site specific risk-based clean up criteria at the former West Melbourne Gasworks Site. These soil acceptance criteria were based on an assessment of the potential health and environmental risks associated with the contaminated soils and groundwater at the gasworks site and the associated Victoria Harbour Precinct.
The Auditor reviewed the proposed methodology and requested a broadening of the scope of the risk assessment to include a wider range of COPCs and of the exposure scenarios to include for example, on site workers during the construction phase.
The report by Egis titled “Site-Specific Clean-up Criteria for the Former West Melbourne Gasworks Site and the Victoria Harbour Precinct” was finalised and released in December 1998.
10.1 SOIL QUALITY ACCEPTANCE CRITERIA
CMPS&F (Egis) adopted a 2-tiered risk-based approach for the development of site-specific risk-based clean up criteria. Tier 1 identified the chemicals of potential concern (COPC) that were expected to be the primary drivers for the site remediation program. The expected COPC based on the previous investigations reviewed by Egis, included polycyclic aromatic hydrocarbons (PAH), BTEX (benzene, toluene, ethylbenzene and xylene), cyanide, arsenic, cadmium, chromium, copper, cobalt, lead, mercury, molybdenum, nickel, tin, selenium, zinc, fluoride, phenol, cresols, sulphate and ammonia. The second tier involved development of site specific clean-up criteria for the identified COPC based on the future land usage of the site.
The Tier 1 COPC and criteria were also partly based on previous studies by Egis for the Gas Industry Association in a confidential report. That report is titled “The Australian Gas Association Site Remediation Task Force – Draft Guidelines for the Assessment and Management of Gasworks Sites” prepared by CMPS&F (Egis) reference SE102.002.005.RevC, and dated February 1997. This report was requested by the Auditor and supplied for reference to justify this part of the study.
The Gas Association report indicated that the five main classes of major contaminants of primary concern on a former gasworks site would be:
• PAHs which generally dominate clean up requirements of surface and near surface soil;
• MAHs (or BTEX) which were anticipated to be potentially major contaminants of groundwater;
• Phenolics (phenols and cresols)- which can be significant groundwater contaminants;
• Inorganics including cyanide, ammonia and sulphate which again can be significant groundwater contaminants; and
• Heavy metals – usually present at elevated concentrations but unlikely to determine clean up requirements.
Other contaminants noted as specific to some activities on a gasworks site included TPH, Asbestos and possibly PCBs in association with electrical equipment.
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The proposed Tier 1 Acceptance Criteria included in the Gas Association document included crtieria derived largely from existing published guidelines such as ANZECC 1992, Dutch Target and Intervention Criteria, and the proposed NEHF health based soil investigation levels by Langley (1996) subsequently the basis of the investigation levels included in the NEPM (1999). Water quality criteria were referenced directly to ANZECC 1992 water quality guidelines.
As the preliminary criteria recommended in the Gas Association report have been subsequently superseded in many cases by the NEPM 1999 and ANZECC 2000 guidelines and by the site specific criteria developed for the site, the report (which was provided in confidence) is not further reproduced as part of this audit.
The 1998 site-specific soil clean up criteria proposed by Egis in their risk assessment, were derived considering the proposed land uses of parkland/open space, high density residential, commercial/industrial and for roadways. The soil acceptance criteria derived by CMPS&F (Egis) (the D1, D2, D3 criteria) were then modified by Egis in discussion with the Auditor, to provide upper limiting criteria for inclusion in the remediation contract signed by Enterra and The Docklands Authority.
In many instances, the criteria indicated as acceptable with regard to potential human health or ecological risks in the Egis report were reduced substantially in consideration of other factors including aesthetic considerations, such as long term odour issues (particularly during a staged construction process), and the potential to impact on services (such as potential damage to PVC by phenolics). The criteria eventually agreed with the Auditor and incorporated into the remediation contract are summarised in Appendix D of this report and also in Appendix C of the Enterra JV Validation report (attached to this report).
The Auditor also requested that the tables of criteria be clearly indicated in the risk assessment documentation as site specific and unsuitable for use on other sites as they were dependant not only on the type of wastes present and the proposed beneficial uses, but also on the hydrogeological setting of the site, including the distance to potential receptors. A clear statement to this effect was included on each table included in the risk assessment report, although this was not carried through to the contract as the contract was itself site specific.
The Auditor’s opinions on the risk assessment were addressed in three letters to the Docklands Authority and to their consultant (Egis) dated 2 December 1998, 25 February and 22 March, 1999. The Auditor considered that the six tables of criteria developed by Egis (formerly CMPS&F) as based on the Tier 1 criteria developed by Egis and as modified by the risk assessment, were acceptable as target criteria for the contract for the clean up of the soils on the site.
Initially 6 tables of criteria labelled ES1 to ES6 were provided as the risk assessment was for the whole of the Victoria Harbour Precinct and included areas outside of the gasworks site. Only the first three, which were labelled D1, D2 and D3 in the contract, were relevant to the former gasworks site. The criteria included in Tables numbered ES4, 5 & 6 were modified to take account of areas of Victoria Harbour outside the gasworks site closer than 60 metres to the Yarra River, as some of the ecologically based criteria were distance dependant due to the method of assessment employed by Egis. These tables were not included in the contract document. Tables D4 and D5 included in the remediation contract, reference criteria for imported fill material quality and soils classified as low level contaminated. Tables D6, D7 and D8 were lists of contaminants required for soil analysis, for groundwater analysis, and for imported fill respectively.
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It was also advised to Docklands that further restriction could be placed on the concentrations indicated in the risk assessment, based on other limitations such as aesthetic (odour) requirements. It was intended that these concerns would be reviewed throughout the remediation process by direct observation and that some of the high concentrations indicated in the criteria for substances such as phenols, would be very much reduced in concentration to limit odour potential.
However, no significant concentrations of phenols were detected during the remediation phase and the only odour issues on the site resulted mainly from the presence of limited areas of ammonia contaminated soils, naphthalene, or a mixture of low concentrations of organic chemicals. As these mainly relate to management of Area B, they will be discussed further in that audit report.
The Auditor noted that some matters could not be finalised from the Egis risk assessment, either through lack of available data, (particularly on groundwater quality), or from the limited scope of the risk assessment undertaken. In particular it was noted that the treatment of groundwater and ecological risks was more from the point of view of the limiting concentrations that might be generated at the boundary of the site based on natural attenuation processes. It was recognised that this could be insufficient in some circumstances where the site was a potential source of groundwater pollution and that further groundwater studies were required to assess this matter. These studies were undertaken in the subsequent Egis groundwater investigations in 1999.
The risk assessment was also limited to targeting the key chemicals that were anticipated to drive the remediation process and therefore did not address all possible chemicals on the site, and the reduced scope of the groundwater modelling on which it was based, was also reduced from a multi-dimensional model to a uni-dimensional model. The Auditor concluded that these issues could be handled in contractual arrangements with the various parties and resolved during the remediation process.
With regard to odour management on the site, the Auditor had previously indicated to Docklands that this could be a major issue during construction and possibly in the long term due to the potential for the presence of many odoriferous chemicals on the site. This was not addressed by the risk assessment. It was indicated to Docklands that the control of odours would potentially require a number of measures including odour blankets, passive venting systems, or temporary sealing of exposed excavations, and this should be incorporated in a suitable odour management, control and monitoring program both during remediation and in the later development of the site. It would also depend on the final quality of the site accepted by any developer that might complete an agreement with Docklands.
As the final end use of the site was not known prior to the start of the remediation contract, the quality acceptance criteria approved for use by the Auditor that were included in the contract covered a range of potential uses based on the limits indicated by the risk assessment, and were aimed at providing areas of undifferentiated use that would include all potential beneficial uses anticipated on the site after consideration of “Any Beneficial Use” as required for issue of a Certificate of Audit.
The limitations and range of beneficial uses anticipated to be covered by the acceptance criteria were as follows:
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D1 Criteria – Soil Quality Acceptance Criteria for soils to a minimum depth of 1 metre for undifferentiated use including parkland (passive) open space, high-density residential and/or commercial use.
D2 Criteria – Soil Quality Acceptance Criteria for soils to a minimum depth of 1 metre below roadways part of the site infrastructure – but not for pavements or parking areas within eventual developments.
D3 Criteria – Soil Quality Acceptance Criteria for soils at depths greater than 1 metre for undifferentiated use as parkland (passive) open space, high density residential, commercial and/or roadways as part of the site infrastructure.
The acceptance criteria specifically excluded the use of the site for low density residential or other sensitive uses that would have similar potential exposure scenarios for young children, for example kindergartens or child care centres with substantial associated landscaped areas.
The primary purpose of the development of the D1, D2 and D3 criteria by Egis for the site was to limit the extent of remediation required to that necessary to achieve the objectives required by Docklands given the proposed land use. It was made clear to Docklands by the Auditor that, whilst these criteria may be acceptable for the proposed developments when completed within the limited range of beneficial uses indicated, the site would still be considered to be contaminated and a Certificate of Audit would have to be refused for the site. However, depending on the final level of remediation achieved, it was agreed with Docklands that the extent of clean-up represented by the modified criteria proposed in the contract, was likely to be acceptable provided that the criteria were viewed as upper limiting criteria and not target criteria by the remediation contractor. This view was applied during the remediation process. Where, if the criteria were exceeded in any way, this was the subject of further review, including where necessary a supplementary risk assessment process. Accordingly a procedure to allow for this process was included in the contract for the remediation.
Ultimately, in monitoring the remediation process, it was found that, as predicted in the Gas Association document, very few of the criteria were significant in arriving at decisions regarding the level of remediation of the soils. Most of the remediation process was controlled by the level of PAH contamination found in the soils and most of the other criteria had little or no impact on the management process. Where necessary, some risk analysis was undertaken by the contractor, for example where ammonia levels in the remediated soils were found to exceed the validation criteria in parts of Area B and the potential for groundwater contamination and ecological risks was examined by Enterra.
Furthermore, the level of conservatism in the use of the criteria was increased during the contract resulting from negotiations with the unions involved. The unions had concerns as to the potential exposure of workers to contaminated soils during the development and post construction periods. They believed that health and safety controls could be less vigilant at these times than during the remediation program, although these potential risks had been taken into account in the risk assessment by Egis and were given specific attention by the Auditor in his review.
As a result of the negotiations between the contractor and the unions on this issue, the values derived for surface soils (ie for the top 1m of the soil profile) were extended for re-used soils to within the top 2m of the replaced soil profile and, where D3 soils were present, it was agreed that these would be indicated by a suitable marker layer. The use of such a marker layer had also already been flagged as a requirement to Docklands by the Auditor in regard to conditions that might be placed on the site in the Statement of
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Audit. This was not initially included in the contract by Docklands as it was assumed it could be included if needed as a variation. The increased depth of D1 layer was implemented on the whole of Area A and has been taken into account by the Auditor in formulating an opinion on the final condition of the site.
It was also noted that the Egis risk assessment assumed the placement of a minimum of 150mm of topsoil wherever the D1 layer is not covered by buildings or pavement. The increased depth of D1 material ultimately placed on the site is considered to make this requirement redundant as it partly relates to the rate of emission of volatiles from the soils and this would also be substantially reduced by the increased depth.
10.2 EGIS GROUNDWATER ASSESSMENTS
A groundwater investigation was conducted by Egis to assess the potential impact of the proposed containment area and existing groundwater contamination on the environment downgradient, including the Yarra River and Victoria Harbour. This was presented to the Auditor in Egis’s report titled “Groundwater Assessment of the Proposed Containment Area, Former West Melbourne Gasworks Site – Revised Final Report” refVP8107.002.Rev2 dated September 1999.
The report embodied several earlier reports by Egis covering the geological setting of the Yarra Delta; groundwater assessments of the proposed containment area; the installation and sampling of additional wells to extend the study; and the review of local groundwater flow influences including sewage discharges and local de-watering activities.
The main purpose of these studies was to assess the feasibility of containment of gasworks related wastes within a containment area on the gasworks site. It also included consideration of the quality and issues relating to the deeper Moray Street Gravels aquifer, as they had not been previously investigated during earlier investigations.
Twenty four groundwater monitoring wells were installed by Egis within three ‘aquifers’ beneath the site, the shallow fill aquifer, the CIS/FBS sediments, and the Morary Street Gravels Aquifer.
The study indicated unanticipated hydraulic gradients within the various aquifers and investigated the causes. These included potential leakage to deep sewers or drains from the CIS/FBS aquifer, and the influence of de-watering, possibly for the casino development and/or the City Link tunnels, that may be responsible for a southerly flow in the MSG.
The groundwater assessment indicated that the CIS/FBS layers were of low vertical permeability and should act as an effective barrier to vertical migration and be protective of the underlying MSG. However there remained potential for lateral migration in these layers in sandy lenses or layers and due to the variation in the thickness of the CIS component.
Egis concluded that, although the MSG was locally contaminated beneath the major deep structures in the proposed containment area (Area B of the site) with PAHs, phenolics, MAHs, cyanide and some metals (particularly Cu, Pb and Zn), it had not migrated off-site as, with one exception, it was not detected in boreholes located to the north, south, east or west of the proposed containment area. Phenolics were detected at low concentration in the MSG to the north west.
The highest concentrations of contaminants were detected in the groundwater sampled from boreholes 7A, B and C that were drilled through what is now known to have been the highly contaminated base of Gasholder 2.
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Additional monitoring wells were sited in the downgradient flow direction south of the site also did not detect off-site migration of contaminants within the MSG.
Leakage to sewers was not considered an issue with regard to gradients within the MSG and flow in the overlying fill layers was indicated to be northwestwards or southwestwards towards Victoria Harbour or the Yarra River. However, the “sinks” within the CIS were considered potentially caused by leaks to sewers or by migration to the MSG via hydraulic connections due to piles constructed for the gasworks. The piles were therefore targeted for further investigation during the early stages of the Enterra remediation as recommended by Egis. However, no evidence of contaminants migrating into or down the wooden piles was indicated in cross sections of the timber analysed by Enterra, as discussed in Section 2.6.6 of their soil validation report.
The Auditor concluded from these studies that containment of the waste soils on site was feasible provided that the main sources of contamination (the gasholders and tar pits) were opened up and liquid contents removed, as the primary contaminated groundwater was located in the fill layers and they could be adequately contained by the underlying low permeability clayey silt formations, provided that a lateral cut-off structure could be effectively designed and constructed.
It was also concluded that, although contaminated groundwater had been detected in the MSG aquifer, this did not appear to be migrating off-site, the water was of limited existing or likely beneficial use due to high TDS, and there was no indication of a hydraulic connection to the Yarra River or Victoria Harbour. This was discussed with the EPA as recorded in Section 5.
A component of this conclusion was a requirement for monitoring of the groundwater aquifers throughout the remediation contract and the installation of groundwater extraction equipment if necessary to manage any failure of the containment system as indicated by monitoring.
Although containment did not proceed and the main sources of contamination were largely removed during remediation of Area B of the site, and by removal of contaminated fills on Area A, the potential for recontamination of Area A of the site from the remaining sources on Area B was considered in risk assessments and modelling undertaken by the Auditor based on the monitoring undertaken during the contract and on the final condition of the site. There also remains some potential for recontamination of the shallow groundwater from re-sue of treated soils on the site as discussed in the Egis 1998 risk assessment.
Excavation and removal of the vast bulk of the contaminated fills that previously existed on the site, and the dewatering of the excavation created, is anticipated to have largely removed the contaminated shallow groundwater and tarry wastes identified in the Egis investigations.
Monitoring has continued in the remaining bores available during and after remediation and in additional bores installed by Enterra to substitute for those lost in the remediation process. Most of the surviving monitoring bores were located outside the site boundaries. Therefore, a number of new monitoring bores were constructed inside Area A, including along the A/B boundary, to provide information on the final condition of the shallow groundwater, the CIS/FBS aquifer, and to confirm the condition of the MSG aquifer. The results of this monitoring are discussed in Section 13 of this report.
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11. SITE REMEDIATION UNDERTAKEN
The Department of Treasury & Finance together with the Docklands Authority furnished a Contract under which the remediation of the West Melbourne Gasworks was to be completed.
Remedial works started on 3 August 1999 and were intended to be complete by September 2000. This target date was not achieved and review of the remediation process by the Auditor has continued until sufficient remediation is considered to have been achieved for Area A, and is continuing in Area B and the GRS.
The site remediation works were undertaken in general accordance with the Remedial Action Plan (RAP) which was compiled by Enterra prior to the commencement of works. As different remedial techniques were employed or discarded as works progressed, these were added and deleted accordingly to the RAP. As a result a total of seven revisions to the RAP were implemented by Enterra throughout the project. The Auditor was provided with copies of these RAPs as they were developed, and comments on their compatibility with remediation objectives were provided to Enterra where considered appropriate. A copy of the RAP under which the remediation of Area A was finalised is included as Appendix E of this report.
11.1 MONITORING OF REMEDIATION OF AREA A UNDERTAKEN BY ENTERRA JV
The remediation process was monitored by the audit team since the inception of the process by Docklands Authority. This included review of each stage of the process including: formulation of the remediation contract by Egis; advice to potential bidders on the audit role and the requirements and limitations of the audit role; review of acceptability of the methods proposed by the preferred bidders; monitoring of the implementation of the work plan; and review of the quality and results of the validation of the site remediation by the contractor.
Throughout the remediation works for both Area A and the remainder of the site a number of issues arose which had some potential to affect the final condition of the site. These are discussed in detail below in relation to the various activities undertaken by the Auditor to monitor processes utilised by the contractor.
11.1.1 Site Meetings
Throughout the remediation program undertaken at the former West Melbourne gasworks, the Auditor and his team attended weekly site meetings to discuss issues relating to progress of the remediation with the Principal, Principals Technical Representative, the Contract Superintendent and the various Site Assessors (mainly the staff of IT Environmental part of Enterra JV, who provided the environmental professionals to manage the environmental monitoring on the site).
By the end of the remediation of Area A, over one hundred site meetings had taken place. The frequency of these meetings allowed the Auditor to have a close understanding of the site operations as they progressed, whilst providing a suitable forum to express his views on matters that were considered could impact on the final condition of the site. It also allowed opportunities to indicate to the contractor where there were matters that could be of concern to the EPA.
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In addition to the weekly site meetings, environmental meetings were held to discuss specific environmental issues. These were attended by the Auditor and/or his team, the Superintendent and/or his team and the Site Assessor.
Other meetings which have taken place throughout the course of the project have included discussion of particular issues, including discussions with the EPA on the interpretation of groundwater issues and remediation to the extent practicable in relation to potential pollution sources located in Area B, and with the Site Assessor and Superintendent regarding specific proposals to vary the remediation methodology and suitability of treated soils for re-use.
11.1.2 Monitoring of Site Progress
Regular monitoring visits to the remediation works have been undertaken by the Auditor and/or Auditor’s team throughout the duration of the remedial works from 1999 to 2002. As well as reviewing the ongoing remedial works as they have progressed over the overall gasworks site, the following specific issues were examined in-situ and reviewed:
• Depth and location of excavations in relation to known location of structures and the anticipated depth of contamination from prior investigations.
• Soil remediation validation sampling techniques.
• Groundwater monitoring bore installation and sampling techniques.
• Material tracking documentation and stockpile identification.
• Management of environmental database (ITEMS).
• Visible condition of examples of re-used backfill materials, including their aesthetic quality.
• Visible condition of examples of each source of fill material imported onto the site.
• Review of exposed sub-structures and validated excavation surfaces where available during site visits.
• Various soil treatment processes attempted and utilised on the site including lime, permanganate & Fenton’s reagent trials and treatment.
Over eighty monitoring visits were undertaken of the former West Melbourne Gasworks site by the Auditor and/or the Auditor’s Representatives over the period of remediation of Area A.
In addition to monitoring of the site works in progress, a number of monitoring visits were undertaken by the Auditor’s representative to the source sites of imported fill material offered by the contractor, in order to gain an appreciation of the proposed fill material in context of the source site and available environmental quality information.
11.1.3 Material Tracking
A significant risk on a major project of this type with regard to final condition of the site arises from the excavation, re-use, handling and/or disposal of large quantities of potentially contaminated soils, and from
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68 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 65 the potential for re-contamination of remediated or uncontaminated areas. A vital aspect of the project management is therefore to put in place at the outset a comprehensive soil management system in relation to all soil movements on the site. A basic requirement of such a system is to allow every soil load to be uniquely identified as to its origin, quality and final destination, and for the remediator to provide suitable supporting documentary evidence that each is being managed appropriately.
Since the commencement of the remediation works, as indicated in the RAP provided to the Auditor, Enterra JV put in place a detailed tracking system and database which was considered by the Auditor to satisfy these requirements. A grid system was set up for the site that allowed reference of all documentation to any 10 metre by 10 metre cell. See plan included in Appendix F of this report.
To provide assurance to the Auditor that the system in place was effective and functioning in the manner expected, the Auditor and Auditor’s representative undertook detailed audits of the material tracking system. The audits were aimed at assessing the system’s adequacy in tracking excavated material and its ultimate fate, and the level of confidence that could be allowed in its accuracy. This was achieved by observations of parts of the system on several occasions during regular monitorin visits. Two detailed audits of the whole system were undertaken on 9 August 2000 and 28 February 2001, and some components of the system were also audited on 21 January 2000 and 29 March 2000.
At both of the detailed audits, the original field records of the movement of soil on randomly selected days were analysed and cross-referenced against the electronic database for accuracy and to confirm the consistency of data transfer. These soils included: material imported from the ComTechPort site (a source of fill material generated by the earlier excavation of the north south road for the Docklands Authority and documented by Maunsell and Egis on behalf of Docklands “North South Road Stockpile Sampling Program Environment Assessment Report” Volumes 1-3, Prepared by Egis Consulting Australia Pt Ltd, August 2000); soil and/or crushed concrete material excavated and processed for re-use within the Gasworks site by Enterra; and material exported off the site by Enterra for disposal.
Each discrete soil movement (each truck load) was tracked through the system to establish whether it’s movement and final fate could be traced. EPA transport records of material classified as “Contaminated Soil” and disposed off-site, were also examined in order to establish whether they were managed in accordance with EPA waste management policies.
The Tracking System - Paper Trail
The tracking system depended on the basic input from Load Sheets provided by the truck drivers that record their daily activities listing all loads including destinations. The trucking contractor for off-site disposal trucks (Fleet) were paid on the tonnage disposed to landfill, which ensured a high degree of compliance with the system such that off-site disposal was adequately recorded in order to ensure payment.
The material tracking dockets used by the truck drivers indicated the time each load moved, the material type (ie. D1, D3, etc), and the cell or stockpile source and destination (eg stockpile, backfill, off-site disposal, etc). Smaller stockpiles when amalgamated in processing were also recorded on the material tracking sheets in a similar fashion. Material disposed off-site to landfill as Contaminated Soil was transported using the required EPA transport docket system as well as Enterra material tracking sheets.
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The Auditor is not aware of any exemption obtained by EJV from the EPA from the tracking requirements of the 1998 Prescribed Waste Regulations.
Each load was entered on the database indicating date, material classification, origin and destination, together with the quantity estimated from the type of truck used and type of material transported. Materials in the loads were identified either by their source cell reference, or by their stockpile type and number. Importantly, at the insistence of the Auditor, the soils were excavated in small parcels and were temporary stockpiles were not combined until each parcel had been separately classified by analysis of the key COPCs. This was to limit the potential for diluting hotspots of material to a lower classification. Once a parcel was classified for off-site disposal or treatment for re-use, it was only combined with soils of a similar classification.
Various stockpiles were created on the site depending on the contamination status of the material and its potential for treatment or disposal. For example stockpile classes included: potential for disposal by co- burning at Hazelwood stockpiles (HSP); hazardous waste for landfill disposal (PWSP); coarse material (CSP); fines stockpiles (FSP); treated stockpiles (TSP); untreated or unclassified stockpiles (USP); landfill stockpiles (LSP); oversized material stockpiles (OSP); and pugmill treatment stockpiles (PMSP).
Fill material brought onto the site was tracked only by the number of loads and quantity brought on to the site each day. Upon entering the site, all fill material was then classified in the same manner, as and imported fill. Thus there was no clear differentiation between different sources of fill after the material was placed in the excavation, except by comparison of the date with the various sources of supply. The fill material brought to site each day could, however, be traced to the range of cells backfilled that day. This could be traced from the total quantities of imported fill material brought onto site, and matched to survey information that provided the location and depth range of the filled area on a daily basis. Survey documentation was reviewed by the Auditor and successfully matched to the tracking records for the days reviewed as part of the audit. Therefore it is possible to identify the general location of any particular fill material that has been re-used or placed on the site.
A range of documentation for randomly selected dates was reviewed by the Auditor to confirm the application of the system by Enterra. Furthermore, all available documentation and EPA transport certificates for movements of “Contaminated Soil” on some randomly selected dates (including 20 and 26 June 2000, and 31 October 2000) was examined, to confirm that documentation of the off-site disposal of hazardous wastes was being tracked by Enterra in an acceptable manner. This included a comparison of Material Tracking Dockets, database entries and landfill weighbridge information for these days. It also included review of the stockpile sources and available documentation on laboratory analyses relevant to the material transported to confirm the appropriateness of its classification. These dockets were also being reviewed regularly by the Superintendent in regard to compliance with the contract and any deficiencies in documentation were brought to the attention of EJV and the Auditor.
A review of the Comtechport imported fill material tracking dockets was also undertaken for 30 November 2000, to ensure that this material was also being tracked in an acceptable manner following delivery by others to the Gasworks site. This material was also reviewed by the Auditor on site as to sorting and handling during the process prior to delivery to the gasworks site. See also Section 9 of this report.
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The Tracking System - Database
The computer based database utilised by Enterra was a sophisticated system which allowed the information entered from the material tracking records to be readily sorted by a range of parameters. The database tracking of each truckload of soil moved on-site generated a large amount of data entered manually into the database from the paper dockets and certificates. As a result, throughout the project, the database ranged from a few days, to approximately several months behind the actual paper trail due to a technical problem with the data-base size, as identified in the February 2001 audit.
The February 2001 audit revealed that the database was generating cell backfill information (ie which type of material had been used for backfill in a particular cell) and to what depth it was placed. As stated previously, however, imported fill was not classified as to it’s site of origin. This inconsistency was eventually eliminated by Enterra and the database continued functioning adequately for the remainder of the remediation of Area A
A general review of the efficiency of the database was also performed by selected tracking of the life of several stockpiles on-site as they were created, treated, and merged with other stockpiles, then either used as backfill or transported off-site for disposal as Contaminated Soil. This included follow up by the audit team on groups of load movements and the original paperwork, to check that the system had been applied as indicated in the database, and was being entered sufficiently accurately to rely on the data base.
A very useful part of the database was the ability to cross match estimated volumes with survey data to confirm a mass balance for excavation stockpiled and transported quantities.
Results of Tracking System Audit
Movements of soil on site were examined for specific dates in April, June and November 2000. It was found that loads, as detailed on the original load sheets on these dates, had been generally correctly identified in the database. This included movement of material stockpiles within the site and material classified for off-site disposal. Most of the loads investigated were tracked successfully completely through the system from excavation to treatment, and to final destination. By reference to available laboratory data, including the original laboratory certificates, they were also found to be appropriate for the destinations recorded.
An apparent anomaly was detected where the database showed material was moved between stockpiles HSP4 (an untreated stockpile) and TSP17 (a stockpile of treated material). The truck dockets for this movement were referenced and these showed the material was used as dry cover over TSP17 to manage odours. A satisfactory paper trail was therefore displayed for those movements.
The tracking load sheets and the transport certificates indicated appropriate use of EPA licensed transport to remove the material to the Tullamarine and Lyndhurst hazardous waste landfills as “Contaminated Soil”. This had also been physically observed on site during the course of site visits carried out by the Auditor and/or his representatives. A large number of loads with EPA Transport Certificates were also examined and matched with landfill weighbridge dockets indicating receipt of the same material at a suitably licensed landfill.
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It was also noted that, at the time of the February 2001 system audit, there was a backlog of data to be entered into the database that appeared to be up to nine months behind the paperwork. Therefore, at the time of the audit, it was a more onerous task for information to be obtained for movements that may have happened in that time. There were also concerns that, if there had been errors in disposal of the material, this would not have been detected in an appropriate time frame. However, this did not appear to have impacted on appropriate management of the materials reviewed, and Enterra were advised to get the data- base up to date to resolve the issue.
No significant inconsistencies were found in the records relating to transport of Prescribed Waste within, or exported from the site. At the time of the August 2000 system audit, the Auditor also had discussions with landfill management with regard to acceptability of the material being imported to the Lyndhurst landfill. It was noted that, although there had been transient issues regarding the level of contamination in some batches transported to the landfills and some odours, this was also being checked on a frequent basis by the landfill management, and it was understood that the material was meeting landfill conditions for disposal at the time the discussions were held.
The database for the general material tracking (not encompassing a backfilling component) was found to be complete with representative data accessible up until early November 2000. This meant that information contained in the database was unable to provide an up-to-date ‘snapshot’ of what was present on site at any given time. This was demonstrated when attempting to determine the fate of stockpile HSP22. All material from HSP22 was transferred to HSP26 by 8 November 2000 according to the paper records examined, however the database indicated 130m3 still present on-site in HSP22. This was a limitation of the useability of the data-base for prompt tracking of materials on the site, but did not prevent adequate management of the stockpiles.
It was also noted that, as it was not possible to monitor up-to-date information for the various stockpiles, there appeared to exist potential for mixing of inappropriate stockpiles together due to lack of readily available data. It was emphasised to Enterra that no such mixing should occur as it would be contrary to the methods agreed with the Auditor and in contravention of EPA policy.
A follow up review of this concern was undertaken in June 2001, once the contractor indicated that it had caught up, and it was found that the database had improved substantially and was approximately three weeks behind in being updated from material tracking documentation at the time of the review. This was considered to be an acceptable lag time, given the quantity of data being entered into the database.
Assessment of the Tracking System
It was concluded that an appropriate and comprehensive tracking system was developed and utilised by Enterra throughout the remediation works. It was found that the system worked well and a high degree of reliance could be placed on the material tracking records for material being excavated and disposed. Whilst the records for the importation of fill material were considered acceptable, a lower degree of certainty was applicable to the placement of imported fill material as its final destination was not specific but rather more general. Nevertheless, it was tracked to a level that was considered practical and acceptable in the circumstances.
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It was also noted that the fill sources were, in general, physically different in terms of colour and the nature of the soil material compared to each other and also compared to the fill and natural soils excavated on the site itself. It was therefore possible to confirm visually where imported fill had been placed on the site during visits on any one day. The plans reviewed by the audit team that had been drawn up by surveyors showing disposal areas on a daily basis, also appeared to reflect the locations used for re-use of fills or imported fill, to a reasonable degree of accuracy within the grid system used.
11.2 IMPORTED FILL MATERIAL
Throughout the remediation of the West Melbourne Gasworks, over 281,000m3 of imported fill material was utilised to backfill the excavated area. A large portion of this was placed on Area A. This material was sourced in varying quantities from 17 sites across Melbourne. With the exception of the stockpile of Comtechport fill, the source material utilised typically comprised natural formations such as Silurian mudstone and siltstone or Brighton Group clayey sands. The source sites and volumes are presented in table 11.1.
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Table 11.1 Sources of Imported Backfill Soils
Source Soil Type Volume (LCM)
University Square, Weathered Silurian Mudstone 50,077 Grattan Street, Carlton County Court, Brighton Group Sandy Clay/ 26,212 Cnr Lonsdale and William St, Weathered Silurian Mudstone Melbourne State Library, Silty Clay/ 1,810 Little Lonsdale Street, Weathered Silurian Mudstone Melbourne Wattletree Rd – Toorak Silty Clay 6,330 60 Wattletree Rd, Toorak St Kilda Baths, Sandy Clay/ Siltstone 4,018 Jacka Blvd, St Kilda Fitzroy St, St Kilda Brighton Group Sandy Clay 8,440 Cnr Canterbury Rd & Fitzroy Street, St Kilda Inkerman Street, St Kilda Brighton Group Sandy Clay 14,236 Cnr Inkerman & Greeves St, St Kilda Victoria Gardens, Richmond Quaternary Alluvium (Clays, 24,750 Cnr Burnely & Victoria Streets, Silts, Sands) Richmond Eastern Freeway, Doncaster Silty Clay/ Weathered 1,380 Eastern Freeway Road Reserve Mudstone 480 St Kilda Rd, Melbourne Brighton Group Sandy Clay 9,898 11 Stead St, South Melbourne Brighton Group Sandy Clay 2,260 44 Grange Road, Toorak Silty Clay 1,035 Girls School, Toorak Sandy Clay 5,884 Cnr Clendon Rd & Millicent Avenue, Toorak Queen Victoria Hospital Silurian Mudstone 55,187 Lonsdale Street, Melbourne Wills Street, Melbourne Silurian Mudstone 490
Comtech Port Fill Silty Clay/Weathered Older 69,020 Commonwealth Technology Port, Volcanics Basalt and reused Docklands fill.
In addition to the imported Fill, as indicated in Table 9 of the Enterra Report, some 31,000m3 of treated soil was also re-used on the site, approximately 10% of the total backfill soils. These are discussed in Section 11.5.
11.2.1 Imported Natural Soils
Most of the fill supplied to the gasworks site was a natural soil or crushed rock material. The information supplied by Enterra as documented in Tables 12A to 12I in their validation report, indicates materials that would be generally classified as “fill material”. These fall within the criteria included in the contract (D4 Criteria) that are based on “fill material” in EPA Information Bulletin 448 of September 1995 “Classification of Wastes” and are therefore considered suitable for re-use on the site.
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Some of the fill indicated minor levels of arsenic contamination or other metals due to naturally occurring mineralisation in the source rocks. These were rejected by the Auditor if the concentrations were found to be substantial. However, minor occurrences of natural mineralisation were not considered significant in the context of the quality of the remediated site, or if in doubt, were examined with regard to their leachability.
A number of potential source sites offered to Docklands for backfill soils by Enterra, were rejected by the audit team based on the history and/or contamination status of the soils indicated by preliminary analytical information obtained by Enterra or visual inspection. These sources were not used by Enterra.
11.2.2 Comtechport Fill
As discussed in Section 9, the so called “Comtechport Fill” was a stockpile of about 80,000m3 of soil excavated from the North South Road (now Wurundjeri Way) by Docklands and stockpiled on the Precinct (then Comtechport) immediately north of the Colonial Stadium within the larger Docklands Site.
At the request of the Auditor, as this material was excavated without segregation by the contractor constructing the major Docklands infrastructure, and was destined for re-use as backfill on the gasworks site, Egis was commissioned by Docklands to undertake a monitoring program in which a sample was taken for every 100m3 placed into the stockpile and analysed for a range of potential contaminants. Survey of the 100m3 cells and sample points was undertaken by Maunsells. A number of hotspots of fill materials excavated from the former rail yards were detected, including PAHs, organochlorine pesticides and a range of metals at concentrations exceeding EPA Prescribed Waste levels.
The hotspots were excavated, segregated and removed from the stockpile by Maunsells under the direction of Egis and the final quality of the stockpile reported by Egis “North South Road Stockpile Sampling Program Environment Assessment Report” Volumes 1-3, Prepared by Egis Consulting Australia Pt Ltd, August 2000.
The stockpile was subsequently partly removed along land adjacent to Footscray Road when a sub-surface failure started to occur, and some of the fill material was placed on the eventual MAB site on the north side of Victoria Harbour. A small volume was also placed as a bund on the eastern boundary of Charles Grimes Bridge Road. This was subsequently removed again when excavation of Area B of the gasworks site started. All of these movements of soils were tracked by Maunsells to retain the integrity of the original database.
Re-use of the soils was managed by GHD on behalf of Docklands and included screening to remove aesthetically objectionable and oversize material, including some piping and other materials that included an asbestos content. It included an initial scrape removal of foreign material including illegally dumped soils and wastes not part of the original stockpile. These added wastes were easily identified as they were randomly dumped and not part of the original structured and surveyed stockpiles. A separate stockpile of material sourced from the stadium was also sampled and analysed to assess its suitability to be added to the main stockpile.
The screening of the fill as it was re-excavated from the stockpile, was carried out under the review of the audit team and the soil produced re-supplied back to Enterra for use on the gasworks site. The Auditor was satisfied that the management measures put in place at each stage of the process were such that there is confidence that the data base gathered by Egis, as documented in their report is representative of the soils eventually re-used on the gasworks site.
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The quality of the soils re-used as indicated by the Egis data base largely falls within “fill material” classification, although there is also some “low level contaminated soil” present as a small proportion of the fill material. It therefore falls within the criteria accepted by the Auditor for re-use on the gasworks site as either D1 or D3 material, and should be managed in a similar manner to D1 soil.
The re-use of treated soils as backfill on Area A of the site is discussed in Section 11.5.
11.3 CONSTRUCTION OF CLAY BUNDS
The Auditor was aware of the presence of significant levels of tarry wastes up to and across the defined boundary of the former gasworks site. Each of the boundary excavations was inspected as the soils were exposed and the presence of any seepage of potentially contaminated material noted.
A number of pipes, ducts, channels and structures also extended across the boundary, many of them potentially containing mobile contaminants or could act as conduits for re-contamination of the remediated areas. Close attention was therefore given to these boundary areas during monitoring visits to the site and by reminders at meetings with Enterra.
During the remediation process, it was noted that some care was taken by the contractor to segregate areas in the site that had been excavated and remediated from those areas where contamination remained. The Auditor reviewed this separation from time to time during the clean up to assess the potential for re- contamination, either by direct contact or by seepage of groundwater into the areas already cleaned. It was noted that, generally seepage rates were relatively low and pumping by Enterra from strategically placed sumps maintained potentially polluted seepage water or non-aqueous phase liquids to levels below adjacent remediated areas.
Enterra maintained a waste pumping system on the site and a large volume water treatment plant for the removal of any tars or other non-aqueous organic wastes from the water pumped out of the excavation. This operated throughout the remediation period under an appropriate Trade Waste Agreement. A minor spill of water from the plant onto the completed Area A in 2002, was inspected by the Auditor and samples taken by Enterra indicated no significant contamination of the backfill soils. The results of the check sampling are included in Appendix H.
As part of the filling process, it was requested that Enterra identify all areas where contamination extended across the site boundary and all areas where there was any potential for recontamination of the remediated site. A bund wall about 600mm to 1000mm thickness of a low permeability clay soil, was then constructed between the boundary and the backfilled areas and keyed into the underlying CIS natural clayey soils. It was considered this was required to limit potential for long term seepage back into the site as it is possible that clean up of the adjacent areas of Victoria Harbour may take many years to complete.
As well as the bund wall, all conduits and pipes were cut off at the boundary and sealed with concrete prior to construction of the clay bund, to reduce potential for contaminated liquids to seep directly back into the remediated areas.
The locations of the boundary cut-off bunds are indicated on a plan supplied by Enterra JV, Figure 10 of the Validation Report.
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11.4 SOIL REMEDIATION PROCESSES
As part of the RAP and proposals originally presented to the Auditor by Enterra JV, it was proposed to treat and either remove off-site or re-use contaminated soils wherever they could be brought within the soil quality acceptance criteria for the site.
The Enterra proposal was that soils close to these criteria would be subject to treatment processes to reduce the level of contamination to within the acceptance levels. This process started with screening to remove hard coarse material that was largely uncontaminated, and together with concrete from foundations and structures on the site, was broken up by a mill, crushed and screened to within acceptable tolerances for re- use in the base of the validated excavation.
The Auditor requested that the re-use of solid inert on the site was put forward in the RAP for review by the EPA in terms of policy on classification of wastes and the Prescribed Waste Regulations. It is understood that no adverse comment was received by the EPA on this matter. The re-use of inert material in this context is therefore considered acceptable by the Auditor in terms of the environmental quality of the site and the relevant regulatory framework.
The fine material left from the screening process and the excavated classification stockpiles maintained by Enterra, were then assessed for immediate re-use on the site, or, where that was not possible, for further treatment to reduce the level of contamination. The Auditor insisted that the soil classification stockpiles would not be merged until they had been adequately characterised for treatment. Where treatment trials indicated that the level of contamination was too high for successful treatment, the material was prepared for suitable disposal off-site by alternative processes and not allowed for re-use. In this way, it was considered that unsuitable contaminated materials were unlikely to be diluted contrary to EPA policy.
Where the initial screening of the stockpiles indicated that treatment could be applied to make the soils suitable for re-use, a number of treatment processes were attempted and are discussed below. Where material was unsuitable for re-use, treatment in many cases still had to be applied to make the material acceptable for off-site disposal.
11.4.1 Quicklime Treatment Process
Quicklime was used to treat PAH contaminated soil on the site and had the dual effect of oxidising some organic contaminants at raised temperatures due to the heat of reaction, as well as chemically fixing other contaminants in the soil such as metals. It is possible that evaporation rather than oxidation during this process drove off some of the more volatile components.
Initially mixing was carried out with excavators directly into the stockpiles. However, this was inefficient and tended to allow powdered lime to disperse with the wind. Enterra therefore implemented the use of a pugmill in August 2000 to mix powdered quicklime with contaminated site soils more efficiently and with greater control. The resultant soil-quicklime mixture created an exothermic reaction of temperature in excess of 100°C that facilitated the oxidation of some contaminants. Enterra report that the reduction in PAH, particularly B(a)P generally was in excess of 30 to 40% in most batches treated (Area A Validation Report, 2001). If treated soil failed to meet the re-use criteria after the first round of quicklime treatment, it was often re-run through the pugmill for a second treatment application. If however, the contaminated soil failed to meet the re-use criteria a second time, it was usually disposed off-site or used to reduce the
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The quicklime-soil mixture was also found to become extremely dry (ie <10% moisture by weight) creating potential dust issues at the site. This was overcome by wetting the treated soils prior to transfer which also accelerated the reaction. The addition of quicklime was also found by Enterra to be effective in creating spadeable soils from excessively tarry soils or sludges found across the site. Enterra found that by the addition of approximately 10% quicklime, these soils and sludges could then be disposed of to landfill rather than the sludges being pumped as a tarry waste by a liquid waste contractor.
Monitoring of emissions on the site was undertaken throughout the project by Enterra, and although there was a component of volatilisation involved in the lime process, the monitoring is understood not to have indicated any significant potential exposures or air quality issues. Odours generated from untreated stockpiles were a more significant issue and complaints by the public were monitored by Enterra and the EPA. A number of complaints were received throughout the contract by Enterra, particularly when large stockpiles of soils were being managed or removed from the site and fresh surfaces exposed. The odour emissions were combated by Enterra using misting sprays and commercial odourcide sprays.
11.4.2 Potassium Permanganate
The addition of potassium permanganate to soils as an oxidising agent for the treatment of PAHs was attempted at both small scale and large scale trials on the site. These trials included four 30 to 50kg trials and one 80 tonne trial adding concentrations of potassium permanganate of up to 1.5% to the contaminated soil.
Enterra found that due to the high Total Organic Carbon (TOC) content of the site soils, the oxidising agent acted more readily on the more chemically available TOC rather than the target contaminants, the PAHs and hence, the concentrations of the PAHs in the treated soil showed negligible sign of reduction.
The use of permanganate, although part of the original proposal by Enterra, was therefore abandoned as a treatment method.
11.4.3 Fenton’s Reagent
Enterra engaged the EM Group to conduct a second chemical oxidation trial in early 2001, this time using Fenton’s Reagent. Fenton’s reagent is a mixture of hydrogen peroxide and ferrous sulphate. The EM Group also employed the use of surfactants and other proprietary liberating agents to wash the contaminated soil, the idea being to release the hydrophobic PAH compounds from the soil matrix making them available to the oxidant.
The EM Group trial proposed five 200 tonne trials. In these trials, the contaminated soil was passed through the pugmill during which the liberating agent was applied. The treated soil was allowed to stand for 12 to 24 hours. The soil was then ground mixed with ferrous sulphate before being passed back through the pugmill a second time in order to apply a hydrogen peroxide solution as the oxidant. The soils were then allowed to stand for a further 12 hours before being tested.
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The EM Group observed minor reductions in the PAH concentrations of the contaminated soil, however these reductions were not considered sufficient by Enterra to approve this method as a cost-effective treatment for soil remediation. The contaminated soil assigned to this trial was amalgamated with material that was ultimately sent to landfill.
The treatment trial was monitored by as the Auditor’s representative, a biochemist, and concurred with Enterra’s decision not to proceed further with the method.
11.5 IDENTIFICATION AND CLASSIFICATION OF SOILS RE-USED ON AREA A
During the project, the volume of soils managed in various stockpiles on the site was monitored as indicated in Section 11.1. As indicated in Table 11.1, up to the time of this audit, approximately 280,000 loose cubic metres of soil was imported to the site, most of it being classified as “Fill Material” and all falling well within the scope of the D1 criteria. This includes the Comtechport fill which, although it did contain some low level contaminated soil components, the bulk of the analyses indicated that most of it could be considered to be “Fill Material”.
Much of the re-used material from the site comprised crushed concrete solid inert material. The volume of re-used treated soil fines that could be classified as “D3” in comparison was relatively minor and is indicated in Table 4.6.8A of the Enterra Report to have been approximately 32,400 loose cubic metres, which comprises about 10% of the total backfill on Area A. Where the D3 was used, as required by the Auditor and agreed with the unions, an orange plastic marker layer was placed at the 2m depth on top of the D3 soils.
As the use of the “D3” material was not organised in any systematic way by the contractor, and Enterra kept no precise survey record of the areas where it was used, it is therefore not possible to identify individual parts of Area A that may be completely clear of contaminated soil. The location of the “D3” classified backfill is indicated in Enterra’s Figure 11 in the validation report. This figure records the location of areas where the marker layer was installed.
Much of the underlying validated soil surface, including areas where it was at more than 5 metres depth below the finished site, also contains some residual contamination within the limits of the D3 criteria.
It is therefore necessary for the whole of Area A to be dealt with as if all of it potentially contains some D3 material. On balance, however, the potential exposure to these soils from the site as a whole is extremely limited and the final condition of the site is considerably better than could have been expected from the original remediation contract as is suggested by Enterra in the conclusions of their report. This is discussed further in Section 13.
11.6 OFF SITE DISPOSAL OF CONTAMINATED SOILS
A major consideration of the audit was that heavily contaminated soils were effectively treated until suitable for disposal and that acceptable disposal options were employed by EnterraJV for material that left the site.
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The main proposal from Enterra was that the bulk of the soils that were too contaminated for re-use would be co-burned at a power station to recover the available energy from the hydrocarbons present. Soils that were unsuitable for this process would need treatment to stabilise the contaminants prior to disposal to a suitable facility.
Documentation has been provided by Enterra on material that has been sent off-site. This includes soils originally earmarked for off-site treatment using co-burning at a Latrobe Valley power station (the HSP stockpiles). The Auditor was not involved in these issues but noted that a trial of the treatment technology for 40,000 tonnes of waste was approved by the EPA. However, this trial did not eventuate and the disposal option was eventually abandoned by Enterra due to adverse circumstances concerning use of the methodology indicated by the receiving power station.
Many discussions took place during site meetings attended by the Auditor regarding the status of this proposal and a large volume (more than 50,000 tonnes) of material was stockpiled on the site for many months awaiting disposal.
As no other suitable and economic technology was found by Enterra to be available, and time limitations on the contract did not provide for other methods that include on-site remediation of the soils, the bulk of the waste soils that could not be made suitable for on-site re-use were subsequently disposed to appropriately licensed landfills. This required in many cases significant pre-treatment with lime to stabilise the soils to a condition suitable for acceptance by the landfill. This was monitored by the Auditor and the management of the waste soils was conducted by direct liaison between Enterra and the landfill operators.
As indicated above, the Auditor reviewed a number of representative EPA transport certificates produced by Enterra for compliance with acceptable protocols. A very large number of EPA certificates were produced by the process as in excess of 250,000 tonnes were eventually disposed to landfill from the whole of the Gasworks site, a substantial proportion of which will have been sourced from Area A. These certificates are very numerous and not individually documented in this Audit report as appropriate copies will have also been received directly by the EPA.
11.7 ACID SULPHATE SOILS
Although the whole of Area A of the site is underlain by Coode Island Silts, a known potentially acid sulphate soil requiring appropriate management in terms of the Victorian EPA’s Industrial Waste Management Policy (IWMP) on Acid Sulphate Soils, this was considered not an issue in regard to Area A of the site as the natural Coode Island Silt formation was largely left undisturbed and in a saturated condition. This is a condition unlikely to allow oxidation to a point where acid sulphate conditions are generated.
Testing on these soils by Enterra indicated that from the presence of sulphates in the soils, both from gasworks related processes and from naturally occurring sulphides in the soil, there was significant acid sulphate potential if the soils were allowed to be oxidised by exposure to atmosphere. The management of the soils both on-site and those removed off-site was therefore considered to be a significant issue by the Auditor.
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Most of the material excavated from the site was an ash waste fill heavily contaminated with tars and PAHs. A small proportion of the excavated soil would have included some of the underlying CIS to remove contamination that had penetrated the CIS material. Re-use of treated soils that may contain a proportion of CIS was therefore a concern. However, in Area A the treated soils comprised a very small proportion of the replaced fill soils (no more than about 10%) as these were largely imported from off-site and comprised the Comtechport fill of mainly Older Volcanics origin, Brighton Group sands and clays, and also the crushed siltstone formations from excavations in the City of Melbourne. The minor volumes of treated CIS that were re-used were also treated with lime which was anticipated to buffer any acid potential due to oxidation of sulphides in the CIS as discussed in Section 6.3 of the Enterra Report.
With regard to Area B, a significant volume of Coode Island Silt clayey soil was excavated and stockpiled as part of the remediation of the deep structures. This material was also stabilised with lime and either removed off-site or re-used in the same deep excavations on Area B as described above. The presence of lime and the replacement of these soils generally below the water table, is again considered likely to act as a buffer to retain the soil in an alkaline state and thus minimise any tendency to generate acid soil conditions. This will be discussed further in the audit report for Area B.
11.8 RISK ASSESSMENTS
Apart from the initial risk assessments and groundwater studies undertaken by Egis to establish acceptance criteria for the site, a number of other risk assessments together with groundwater modelling were undertaken in order to upgrade some of the generic criteria included in the original assessment by Egis.
These included modelling and risk assessments with regard to ammonia compounds that remained within Area B that are not relevant to Area A, but also assessments regarding residual sources of pollution that comprise dispersed non-aqueous phase liquids (NAPLs) that may remain within the deep excavations on Area B and have the potential to migrate to groundwater and possibly impact on the environmental quality of Area A. These are considered below.
11.8.1 IT Environmental (2001)
Summary of IT’s Findings
Phase separated hydrocarbon (PSH) (non-aqueous phase liquids) impact was observed underneath the base of the eastern side of the large gasholder located on Area B of the site immediately beneath the former Charles Grimes Bridge Road and approximately 50 metres east of the boundary between Area A and B.
Additional investigation of soils under the gasholder confirmed a hydrocarbon film to be present at levels between 6 and 8 metres below ground. Following an assessment of the mobility in groundwater in relation to this impact, IT Environmental (Australia) Pty Ltd (IT), the site assessor part of the Enterra Pty Ltd (Enterra) Joint Venture, carried out a quantitative risk assessment as provided for in the remediation contract.
The Enterra risk assessment concluded that adverse non-cancer health effects for the population using the park for recreational purposes are unlikely.
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Auditor’s Review of Enterra Risk Assessment
The draft risk assessment document was generally reviewed in accordance with the “National Environment Protection Measure for the Assessment of Contaminated Sites, Schedule B(4), Guideline on Health Risk Assessment Methodology” (NEPM, 1999). The review was divided into the key areas of risk assessment; namely data collection and evaluation, toxicological assessment, exposure assessment, risk characterisation and reporting.
A number of issues were found with the document that restricted its potential for use by the Auditor. These included:
• No key objectives for the assessment of risk identified.
• The general approach to risk assessment was not outlined.
• It was not clear if the vapour model used was based on USEPA standard guidance for risk assessments, or if the data available in guidance documents referred to in the NEPM had been incorporated into the models for use in Australia (where relevant).
• The risk assessment did not present a summary of the investigations and results on which it was based.
• Little site information was included such as description of the site, its surroundings, proposed land use, site geology, hydrogeology, topography or environmental setting which would be the basis for establishing appropriate exposure pathways and receptors in the exposure assessment.
• The extent of the contamination was not adequately defined and there was no discussion on the potential for site related chemicals to migrate off-site.
• The basis for selecting chemicals of potential concern (COPC) was unclear.
• No assessment was included as to the adequacy of the available data for use in the risk assessment. No data gaps were identified.
• The toxicity assessment presented generally utilised data available from the USEPA. The NEPM guidance requires the use of WHO and NHMRC data in preference to the USEPA, if available.
• The use of oral slope factors for PAHs is not directly relevant to the inhalation pathway.
• The exposure assessment presented was limited. The key exposure pathway identified was the migration of volatile COPC from the groundwater to the surface of the ground. It was not made clear whether the groundwater was also migrating to off-site environments. Only outdoor air exposure was considered, however, if restaurants or other public facilities are constructed, then exposure in the indoor air environment may need to be considered.
• Only adults had been assessed within a recreational exposure scenario whilst children are typically more sensitive receptors due to their lower body weight.
• The parameters and assumptions used for predicting air concentrations from the groundwater source were not presented.
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• Risk characterisation was presented, however as a number of major deficiencies were noted in the draft assessment, they could affect the outcome of the risk assessment.
The Enterra/IT risk assessment was therefore not accepted as appropriate for use by the Auditor. As Enterra considered that there was no reason for extending the risk assessment, the Auditor had to consider undertaking his own study of the risks that may relate to any remaining NAPLs on Area B of the site in terms of its potential impact on Area A.
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11.8.2 Auditor’s Risk Assessment (2001)
Summary
The Enterra/IT risk assessment was considered insufficient to allow the Auditor to assess whether remediation had been completed to an acceptable degree by the contractor. A further health and ecological risk assessment was therefore required to assess the extent of potential risks relating to non- aqueous phase liquids that may be left in the ground beneath former Gas Holder No2 at the end of remediation, and its potential impact on Area A. The Auditor therefore undertook groundwater modelling with a human health and ecological risk assessment for the former West Melbourne Gasworks site at Piggott Street, Melbourne Docklands to satisfy the needs of this Audit.
The risk assessment followed the identification by Enterra of significant residual contamination in deep soils remaining on the eastern portion of the site, (Area B). In particular, the Auditor’s risk assessment was limited to assessment of the risks associated with Phase Separated Hydrocarbon (PSH), associated with soils surrounding and beneath the location of the excavated Gas Holder 2 (GH2) located within Area B as the closest source to Area A. A second risk assessment and the associated groundwater modelling, was undertaken later for the remainder of potential sources (Gasholder 1 and a Tar Pit) and confirmed the results of the initial risk assessment.
In the context of Area A of the site, the potential risks to human health associated with the PSH for future residents of Area A were assessed. This assessment concluded that potential risks to human health associated with the exposure to the PSH that may be present within the groundwater at the interface of Areas A&B and in the potentially residential Area A, were expected to be low and essentially negligible. The latter risk assessment for Gasholder 1 and the Tar Pit arrived at similar conclusions.
These conclusions were documented in Dames & Moore’s reports titled:
“Human Health Risk Assessment, Gasholder 2, Former West Melbourne Gasworks Site, Docklands, Victoria” Dames & Moore report ref 37858\005\report\HRA R001 Rev1.doc, dated September 2001.
This was presented to the EPA but was subsequently superseded by:
“Fate & Transport and Human Health Risk Assessment, Gasholder 1, 2 and Tar Pit, Former West Melbourne Gasworks Site, Docklands Victoria” Dames & Moore reference 37858\005\report\FT&HRA_Rev0.doc, dated November 2001.
11.9 FATE & TRANSPORT MODELS
11.9.1 IT Environmental (2001)
Summary
Phase separated hydrocarbon (PSH) impact was observed underneath the base of the eastern side of the large gasholder located immediately beneath the former Charles Grimes Bridge Road. Additional investigation of soils under the gasholder confirmed a hydrocarbon film to be present at levels between 6 and 8 metres below ground. Whilst monitoring wells, which were installed during this investigation, did not show measurable PSH impact, a hydrocarbon sheen was observed in some to the wells.
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As a basis for development of the health risk assessment, and in order to examine the implication for groundwater quality on the site, following the detection of the PSH, IT Environmental (Australia) Pty Ltd (IT) on behalf of Enterra carried out a fate and transport assessment in order to determine the fate of the impact.
Auditor’s comments on Enterra Fate & Transport Model
The Auditor’s view of the Phase Separated Transport (PSH) fate assessment undertaken by Enterra Pty Ltd (Enterra) is that it was somewhat simplified for it’s objective, which was to provide a high level of assurance that groundwater containing potentially carcinogenic compounds would have negligible impact on human health or the environment, specifically as discharge to the Yarra River, a short distance from the site.
Firstly, the abbreviated approach adopted by Enterra did not use actual site data and it’s reliance on what were considered to be conservative assumptions appeared to be inappropriate for this project. A brief review of the data provided suggested the following:
• Sources and lateral extent/s of PSH as either dense non-aqueous phase liquids (DNAPL) or light non- aqueous phase liquids (LNAPL) in the Coode Island Silts had not been adequately delineated, and
• Lateral extent of dissolved phase plumes associated with PSH sources did not appear to be adequately delineated.
It was considered the methodology was over simplified. It comprised multiplication of adopted guideline values for each selected indicator compound by 2 until corresponding solubilities were reached, then multiplying of the number of times the calculation was done by the half lives to provide theoretical times for bio-degradation to occur. These times were then multiplied by a generic linear velocity for groundwater flow in the silt.
The statement that a plume would not go further than 10 m before concentrations drop below guideline values was considered to be too great an assumption. It was considered that this approach could be acceptable as a first pass assessment, but needed to be supported by a more rigorous examination of the assumptions and calculations for the purposes of the Audit.
Secondly, there were concerns with the groundwater "sink" theory advanced. Although it was possible in this case, there was only one bore (MW16B) that could be linked to such a groundwater "sink".
A computer based groundwater flow and contaminant transport model (preferably on a 2-dimensional basis) would have been preferred for the site. The fate of contaminants should be based on actual groundwater flow and contaminant characteristics of a site and not from laboratory bench-top biodegradation values. Literature based values should be used in an integrated flow and transport model for sensitivity analysis of conservative contamination scenarios. Modelling the fate of the contaminants from confidently known and delineated source areas and current plume concentrations at those areas would be a basis for model predictions and fate assessments.
It was also considered by the Auditor that the model should be based on site specific hydraulic and physical aquifer properties (i.e. not generic publication values) in order to minimise the use of sweeping assumptions. Actual values for the site were available from the studies undertaken by Coffey Partners for the containment. As none were available for the sandy layers in the Fishermen’s Bend Silt, these should
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Model outcomes should show predictions of the extent and concentrations of plumes from source areas under steady state groundwater flow and biodegradation conditions. The output should show predicted impacts to the plumes (ie in direction and extent) if groundwater flow conditions change in future (eg from inferred "sink" to normal flow conditions). An assessment should also be made into the possibility that LNAPL sources could migrate with time and the consequence of such an eventuality. A model could also allow for assessment of unknowns such as preferential sand flow paths to the Yarra River that were not identified or missed during drilling by adding a further level of conservatism
Overall, the Auditor did not accept the calculations or outputs of the fate and transport modeling reported by Enterrra/IT and requested that an appropriate study be undertaken.
11.9.2 Fate and Transport Model Undertaken by the Auditor (2001)
Summary
In order that the Auditor could assess whether remediation has been completed to an acceptable degree and “the extent practicable” by the contractor, Enterra Joint Venture, a fate and transport model was required to assess the extent of potential risks relating to identified non-aqueous phase liquids to the nearby surface waterbodies and land. The Auditor therefore undertook a fate and transport investigation of the PSH impact in Area B of the former West Melbourne Gasworks site and its potential to impact on Area A, the subject of this audit report.
Due to the identification of the PSH in the FBS at the base of GH2 excavation, (and subsequently in Gasholder 1 and the Tar Pit) there was concern that hydrocarbon contaminants could migrate away from the former GH2 site via advection in groundwater, either through the FBS or overlying aquifers, once site remediation works have ceased and groundwater levels on the site return to pre-remediation levels. This possibility was ignored in the Enterra model.
A computer based numerical groundwater model was used as a tool to assess the likely physical dimensions and chemical attributes of the groundwater contamination in space and time, particularly its possible migration off site, migration to the proposed residential Area A and potential discharge to receiving surface water bodies in the down hydraulic gradient direction from the former GH2 area.
Based on the inherent assumptions described in the report, the modelling predicts that the selected contaminants of concern were unlikely to reach the Yarra River and Victoria Dock and therefore should not have an ecological impact or constitute a health risk in recreational use of these water bodies. It was also predicted not to reach Area A such that concentrations of the contaminants of concern would exceed concentrations that would constitute a potential health risk to residents, even if a plume of dissolved phase contaminants spread through the fill layer at shallow depth after full recovery of the water table.
These conclusions are documented in the Dames & Moore reports titled:
“Contaminant Fate & Transport Modelling at West Melbourne Gasworks Site, Docklands” reference 37858\005\report\GWM R001-Rev0.doc, dated July 2001,
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This report was also presented to the EPA and subsequently superseded by
“Fate & Transport and Human Health Risk Assessment, Gasholder 1, 2 and Tar Pit, Former West Melbourne Gasworks Site, Docklands Victoria” reference 37858\005\report\FT&HRA_Rev0.doc, dated November 2001.
This report is included on the CDs attached to this report for reference.
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12. REVIEW OF REMEDIATION/VALIDATION DATA
12.1 OVERVIEW
The following is the Auditor’s appraisal of the validation data presented by Enterra JV to substantiate the final condition of Area A of the site. The Audit addressed the following:
• Compliance of the investigation with the requirements for Site Assessment Reports, as listed by Vic EPA in “Environmental Auditor (Contaminated Land), Guidelines for Issue of Certificates and Statements of Environmental Audit”, Pub. No. 759, May 2001;
• Appropriateness of assessment guidelines and whether they have been adequately interpreted and applied.
• Appropriateness and adequacy of the assessment with respect to the potential for contamination on the site.
• Validity of the investigation data with respect to acceptable data quality objectives.
• Appropriate and adequate interpretation of the data with justification for remediation decisions taken on site and validation conclusions reached as to final quality of the site.
The objective of the data collection activities during the remediation activities was to provide a representative assessment of the final environmental condition of Area A of the former West Melbourne Gasworks site, and to evaluate whether Area A is currently suitable for its proposed beneficial uses and not impacted adversely by on-site or off-site activities.
It is considered that the scope of the assessments undertaken by Enterra was broadly consistent with achieving these objectives.
12.2 LABORATORIES USED BY THE SITE ASSESSOR
The following laboratories were used by the site assessor:
Primary Laboratory: Gribbles Analytical Laboratories (Gribbles) Pty Ltd
Secondary Laboratory: Australian Laboratory Services Pty Ltd
The laboratories utilised are NATA accredited for the analytical suites performed and the certificates of analysis provided with the validation report were NATA approved.
The methods used by each laboratory did, however, vary in some respects in a number of important analyses. This initially showed up in review by the Auditor of interlaboratory QA for a number of validation analyses, where RPDs calculated by Enterra and checked by the Auditor, were found to exceed acceptable limits.
This matter was investigated early in the validation program and recommendations made to Enterra to modify assessment methods to comply with the acceptance criteria and allow appropriate comparison between the primary and secondary laboratory results. As a result, Enterra modified the methods being
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88 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 85 used by Gribbles Laboratories and reanalysed a number of the samples for cyanide and, for those that had been held too long to be valid for re-testing, undertook a number of comparative analyses of fresh samples using both methods. It was concluded that the differential between the methods used was insufficient to have altered the management approach to the soils analysed.
This is discussed further in the appraisal on the quality of the laboratory testing in Section 12.5 of this report. ALS was also used by the Auditor to undertake some check sampling on the validated soils in Area A and to assess some odorous soils from Area B.
12.3 ANALYTICAL METHODS
Analytical methods and laboratory levels of reporting (LORs) for the primary and secondary laboratories are summarised in Tables 12.1 and 12.2.
Table 12.1 Analytical Methods for Soil
Analyte Gribbles LOR ALS LOR mg/kg mg/kg Fluoride 208 Anions (sol) by chromatography 2 EK-040S 1 Sulphate 208 Sulphate (as S) by IC ED-040T 10 Ammonia as N 240 Ammonia by Distillation EK-055 2 Cyanide 236 Cyanide by UV-Vis (SFA)dry EK-026 Based on NEPM 1 weight Method 403 Mercury 404FIMS Mercury by Vapour AAS EG-035T 0.1 TPH (C6 to C9) 504P&T Based on USEPA 8260B 20 EP-071-SS 2 TPH (>C9) 501-FID Based on USEPA 418.1 20 EP-071-SS 50 to 100 PAH 505-MS 0.1 EP-075B-SS 0.5 to 1 BTEX/MAH 504P&T Based on USEPA 8260B 0.1 EP-074A-SS 0.5 Tot’ Halogenateds 502HS GC based on USEPA 5021 0.005 to EP-074-EE 0.5 to 5 0.05 Arsenic 406FIMS based on USEPA200.8 EG-005T 1 Cadmium 1 Copper Cobalt Lead Molybdenum 5 Nickel Selenium 3 Tin 2 Zinc Chromium (III) 406 & 250 Based on USEPA 7196 & EG-049 1 200.8 Chromium (VI) 250 based on USEPA 7196 EG-050 1 OC Pesticides 506ECD Based on USEPA8081 0.1 EP-068A-SS 0.05 to 0.2 Cresols 508MS Based on USEPA 8041 0.1 - - Phenols 508MS Based on USEPA 8041 0.1 EP-075A-SS 0.5 & 1 indiv
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Table 12.2 Analytical Methods for Groundwater
Analyte Gribbles LOR ALS LOR mg/L mg/L TPH 501-FID EP-071-WS C6-C9 0.04 0.02 C10-C14 0.04 0.05 C15-C28 0.1 0.1 C29-C36 0.1 0.05 Antimony E102.01 ICP-MS 0.005 EP-020F 0.001 (0.01, Se) Arsenic Beryllium Cadmium Chromium Cobalt Copper Lead Manganese Molybdenum Nickel Selenium Tin Zinc Calcium E102.01 ICP-AES 0.1 ED-005F 1 Magnesium ED-010F 1 Phosphorus EK-067 0.01 Sodium ED-015F 1 Chloride E118.01 by Ion Chromatography 0.5 ED-045 1 Fluoride EK-040 0.1 Sulphate as ED-040F 1 Sulphur Ammonia E118.02 by Segm’ted Flow Analysis EK-055 0.01 pH G516.11 EA-005 0.01 TSS & TDS G520 EA-015 1 BTEX/MAH 502HS by headspace 0.005 EP-074A-WS 0.001 Tot’ Halogenated 502HS by headspace EP-074E-WS 0.01 PAH 505-MS EP-075B-WS 0.002 Individual 0.001 Total 0.02 OC Pesticides 506-ECD 0.001 EP-068A-WS 0.0005 Phenols / Cresols 508-MS 0.001 EP-075A-WS 0.002 Mercury E102.03 by Flow Injection, Vapour 0.001 EG-035F 0.0001 AAS Total Cyanide G510.02 by colorimetry (SFA) 0.01 EK-026 0.005 Bicarb. Alkalinity G536.11 by titration Nitrogen E118.01 by Ion Chromatography 0.2
12.4 ANALYTICAL DATA VALIDATION
Analytical data validation is the process of assessing whether data are in compliance with method requirements and project specifications. The primary objectives of this process are to ensure that data of known quality are reported, and to identify if the data can be used to fulfil the overall project objectives.
The data validation guidelines adopted are based upon AS4482.1 and data validation guidance documents published by the United States Environmental Protection Agency (US EPA). The process involves the checking of analytical procedure compliance and an assessment of the accuracy and precision of analytical
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90 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 87 data from a range of quality control measurements, generated from both the sampling and analytical programs.
Specific elements of data validation that can be readily checked and assessed for ESA projects include:
• Preservation, labelling and identification, and appropriate storage of samples upon collection and during transport to the laboratory;
• sample holding times;
• use of appropriate analytical and sampling procedures;
• required limits of reporting;
• frequency of conducting quality control measurements;
• laboratory blank results;
• field blank results;
• trip blank results;
• field duplicate results;
• laboratory duplicate results;
• matrix spike/matrix spike duplicate (MS/MSD) results;
• surrogates spike results; and
• the occurrence of apparently unusual or anomalous results, e.g. laboratory results that appear to be inconsistent with field observations or measurements.
The need to appropriately identify, preserve, store and analyse samples within a specified time period after collection may be required in order to maintain sample integrity. Such actions aim to ensure that the loss of analytes, resulting from the occurrence various biotic and abiotic processes, is minimised.
Various guidelines have been published relating to sample preservation, storage and holding time requirements of environmental samples. If non-compliance to these requirements is observed for a given sample or samples, professional judgement should be used to evaluate the extent to which sample integrity and hence sample results may have been compromised.
12.5 QUALITY OF INFORMATION SUPPLIED
12.5.1 General
The review of documentation provided as outlined in the previous sections of this report, is considered to be of adequate quality and sufficiency for the purposes of this report and was supported by the Auditor’s
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91 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 88 observations during the site monitoring of the field investigation and remediation, and the Auditor’s review of previous studies upon which the field work was based.
The information provides:
• historical data, indicating previous uses of the site;
• data indicating the current and recent uses of the site;
• a distribution and frequency of sampling locations to obtain a valued judgement of the contamination status of the site;
• adequate accuracy and reproducibility of results verified via QA/QC sampling;
• an analytical suite sufficient to identify a broad spectrum of likely contaminants;
• soil and groundwater contamination sampling procedures suitable to produce accurate results for the purposes of this audit.
The potential contaminants, as indicated by the known history of the site and observations, and as reviewed by the Auditor, are considered to have been identified and sufficiently assessed in the investigations by the use of field observations and laboratory analysis, and have been addressed in the human health risk assessment by the derivation and implementation of site specific clean-up criteria (Egis, 1998).
The laboratory methodologies and detection limits used by the laboratories employed in the site validation undertaken by Enterra, namely Gribbles and ALS, have been reviewed. This included review of the reported in-house laboratory methodologies and detection limits. The laboratory review by the Auditor was undertaken in two components. Firstly, as a progressive review of weekly environmental reports presented to the Auditor throughout the duration of the site remediation process, and secondly, as a review of data presented in the Area A Soil and Groundwater Validation Reports prepared by Enterra JV. The in- house laboratory methodologies and detection limits that have been employed by both Gribbles and ALS are considered to be acceptable although a number of the groundwater analyses used LORs that significantly exceeded surface water ecosystem protection criteria.
The resultant tables of data presented in the reports as representing the condition of the site have also been compared by the Auditor for accuracy with the original test certificates supplied in the reports and found to be generally representative of the reported concentrations. An overall check was conducted randomly through the data tables to look for systematic and random anomalies. Approximately 10% of the data was then initially checked in detail for systematic errors. A number of systematic errors were identified and corrected by Enterra for re-submission in a revised report. Approximately 20% of the data summarised in the revised report was then checked in detail following these corrections and found to be representative of the results recorded in the laboratory certificates. The data summary tables provided in the Enterra report are therefore considered to be representative of the analyses conducted.
The quality of the laboratory analyses has been assessed for the Area A soil and groundwater validation reports by means of inter-laboratory duplicate analysis, blind duplicate analysis, internal laboratory duplicate analyses, and by analysis of laboratory matrix spikes and blanks. The Auditor notes that Enterra
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92 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 89 reported that they have reviewed 1 in every 10 samples for laboratory Quality Control and that a “more thorough review of this data will be completed at the time the subsequent (Area B) report is submitted”.
The Auditor undertook his own quality review of the data presented in two components. One component was a progressive review of the weekly environmental reports presented to the Auditor throughout the site remediation to verify that the results presented were sufficiently reliable to be accepted by the Auditor as representative of site conditions. The second component included a detailed review of the QA data presented by Enterra in the Area A Soil and Groundwater Validation Reports. The number of laboratory tests and equivalent QA laboratory duplicates and matrix spikes reported by Enterra, have also been reviewed by the Auditor. This has been compared with the project Quality Analyses section as presented in Section 3 of the Validation report.
The frequency of duplicate and triplicate samples that has been employed by Enterra was found to be approximately 10% of the total analyses conducted for the site validation and is therefore considered to be acceptable in terms of the recommendations included in Australian Standard AS4482.1. This has also been supported by the in-house quality control programs undertaken by the laboratories utilised, including numerous internal duplicates and matrix spikes, etc, which are considered to be in reasonable proportion to the numbers of samples analysed.
Enterra departed in one area from the recommendations in AS4482.1 as they did not employ the collection of field blank samples. Where questioned on this, they indicated that their rationale was that all of the samples, including groundwater samples, were collected with the use of dedicated single use and/or disposable equipment, including use of one time protective latex gloves to collect soil samples and dedicated and disposable balers to collect water samples. In collecting soil samples, they also collected samples by hand from freshly exposed surfaces that were broken open and not contacted by excavation plant. It was their opinion that there was little opportunity for cross contamination. As, due to the overall level of contamination on the site, and as the potential is for a more conservative interpretation of the laboratory analyses if some degree of cross contamination has occurred (despite Enterra’s confidence that it was unlikely), this procedure was considered by the Auditor to be acceptable in the circumstances.
For the above reasons and based on our review and observations made on site throughout the project, it is considered that the amount of Quality Assurance data collected is sufficient to provide confidence in the results from the primary analyses.
Except for some differentials as reported and discussed by Enterra in some of the analyses, the bulk of the QA analyses indicate an adequate degree of consistency in the results. Enterra have provided Relative Percent Differences (RPDs) calculated for both the intra-laboratory (blind duplicate) and inter-laboratory (triplicate) quality samples. The Auditor has also checked a significant proportion of the duplicate analyses reported by Enterra by re-calculation of individual RPDs from the source data provided and has found that the Enterra RPDs are representative of the duplicate analyses conducted.
A large number of RPDs could not be calculated as both results were below detection limits. Generally in the situation where either the primary or the duplicate sample result were below the detection limit, Enterra calculated the RPD based on half that detection limit. This could lead to some underestimate or overestimate of the RPD and was reviewed on that basis.
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12.5.2 RPD analysis - Soil
Enterra reported that 8,300 soil sample RPDs were calculated and of these, 1,739 RPDs (approximately 20%) exceeded the project acceptance limit of 30% (or 50% for organic analytes). The majority of these soil RPD exceedences appeared to be random in nature and were recorded for samples where the concentrations of the primary and QA/QC sample were both within the same range of soil re-use acceptance criteria (ie D1 or D3 criteria). The Auditor has also checked the frequency of RPD exceedences that may have resulted in the soil being incorrectly classified on the basis of the primary sample, and agrees with Enterra that this is in the order of no more than 1% of the total RPD exceedances.
As discussed in the previous section, a number of QA issues were identified by the Auditor in the weekly environmental reports early in the remediation contract and requested that Enterra review the methods in use. Where frequent RPD exceedences were observed for a number of the soil analytes, especially between the primary and secondary laboratories, Enterra classifies these as systematic errors. Systematic errors occurred for 6 analytes, namely sulphate, TPH>C9, benzo(a)pyrene, cyanide, fluoride and phenols. These were discussed with the Auditor and Enterra undertook the following remedial actions:
• Sulphate, cyanide and fluoride: a review and subsequent synchronisation of the methods used by both the primary and secondary laboratories;
• B(a)P: a review of B(a)P and total PAH data revealed no decipherable trends in the reported RPD exceedances and therefore no further action was taken;
• TPH>C6: a review of data revealed no decipherable trends in the reported RPD exceedances, and concluded that any misclassification of the soil was unlikely to have had a significant effect on the 95% UCL calculated and therefore no further action was taken; and
• Phenols: a comparison between the results of the primary and secondary laboratory revealed that no data from either laboratory exceeded the D1 criteria and hence no further action was taken.
With the cyanide analysis, the initial method being used by Gribbles was considered by the Auditor not to be consistent with the method set out in the ANZECC “Guidelines for the Laboratory Analysis of Contaminated Soils” 1996. After the method was adjusted to reflect a true “Total Cyanide” analysis method to allow comparison with the site acceptance criteria, which were also quoted as “Total Cyanides”, comparison of the results between the primary and secondary laboratories indicated a much closer degree of correlation.
Enterra also compared both methods used to examine the potential error range. They concluded that there would have been no change in their management of the soils tested. The Auditor also reviewed the earlier analyses of cyanide undertaken by Enterra prior to rectification of the test method. This review indicated that on-site management of the soils was unlikely to have been affected by the potential errors in the results reported, therefore no further action was taken by the Auditor except for continued monitoring of the QA data supplied for later analyses.
12.5.3 RPD analysis - Groundwater
Enterra reported that 1,360 groundwater sample RPDs were calculated on results up to September 2001, and of these, 169 RPDs (approximately 12.5%) exceeded the project acceptance limit of 30% (or 50% for
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94 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 91 organic analytes). The majority of these groundwater RPD exceedences were for metal analytes and recorded for samples where the concentrations of the primary and QA/QC sample were within the same reuse criteria (ie either both greater than or less than the ANZECC freshwater and marine water guidelines). The Auditor has also checked the frequency of RPD exceedences that may have resulted in the groundwater being incorrectly classified on the basis of the primary sample, and agrees with Enterra that this is in the order of 1.3% of the total RPD exceedences.
Based on the quality assurance procedures applied, as observed during the site monitoring, and from review of the analysis of the results documented throughout the project in the Weekly Environmental Reports, Groundwater Monitoring Events, and the Area A Validation Report, it is considered that the chemical analysis results provided in the Enterra reports, are sufficient to form conclusions as to the current environmental status of Area A of the site with an acceptable level of confidence.
On this basis, it was considered that there was no requirement for further verification of the environmental status of Area A of the former Gasworks site by additional sampling and laboratory testing other than that already undertaken by Enterra or as discussed in Section 12.6 below.
12.5.4 Surface Revalidation
Part of the backfilled Area A was used in the latter stages of the remediaton of the Gasworks for stockpiling of contaminated soils excavated from parts of Area B and for processing of these soils through a Pugmill. Protective bunding and a plastic sheet were layed down and reviewed by the Auditor prior to storage of contaminated soils on the backfilled areas.
At the request of the Auditor, the contaminated soil stockpiles and operational plant were removed from Area A and all remediation activities stopped on that part of the site prior to completion of the audit for Area A. This has been undertaken by Enterra and the area re-levelled and cleared of all plant machinery and operations and the boundary of the remediated area indicated by bollards and hazard tape.
Enterra have subsequently reported surface revalidation samples were collected from every fourth 10m x 10m alpha-numeric grid cell in every second alphabetical column across the areas where there was potential for re-contamination due to trafficking or contaminated soil storage. In areas where soil destined for landfill were stored in the plastic covered and bunded areas, the revalidation sample density was increased to one from every second 10m x 10m alpha-numeric grid in a checker pattern similar to the in- situ validation sampling of the base of the excavation. This methodology was adopted in consultation with the Auditor. The methodology and results of the surface revalidation of Area A are presented in the Addendum to the Enterra validation report titled “Area A Validation Report Addendum – Surface Revalidation Sampling” Enterra Ref: 4626/1.25 dated 21 September 2001.
The Auditor generally accepts the results presented in this addendum report and the surface at the finished grade is now considered acceptable for use, and the remaining stockpiled soils appropriately removed.
No more remediation activities are taking place on Area A, however a small spill occurred from the waste water treatment plant (WWTP) located to the west of the western boundary of Area A and impacting on grid square J29. This area was subsequently re-sampled by Enterra for the range of potential contaminants indicated by the most recent analyses on the water in the WWTP. Although some TPH and PAH was detected, concentrations were did not exceed D1 criteria and were not dissimilar to levels recorded from
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95 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 92 adjacent soils in grid square K29 not affected by the spill. These results are summarised in Enterra’s letter of 27 February 2002, included in Appendix H for reference.
12.6 UST VALIDATION
During the initial review of data provided by Enterra with a draft of the validation report, it was noted that although three underground storage tanks (USTs) had been removed from Area A of the site, no specific validation data was provided for the former location of these tanks in the Enterra Report, and the routine base validation samples were too widely spread to ensure that any potential “hot spots” had been adequately removed.
Accordingly, it was requested by the Auditor that additional validation sampling and analysis be performed at the former location of each UST in the underlying natural soils. This was undertaken by Enterra and a check sample taken by the Auditor. Two of the samples indicated no issues with the UST locations, however the Auditor’s sample from approximately 3 metres depth for the third location, indicated the presence of PAHs exceeding D3 criteria and a minor level of associated TPH contamination.
As it was possible that the contamination was within acceptable limits of variation (of up to 2.5 times) compared to the acceptance criteria, at the request of the Auditor, additional samples were undertaken in the vicinity of the former UST to establish whether a significant hot spot might be present. The Auditor also took his own samples to verify the results of the investigations mindful of recent indications from the EPA that it was expected that Auditors undertake their own testing to verify site conditions. As the remediation and validation program was largely complete before this directive was received, this was not considered for the earlier validation testing where the Auditor’s judgement indicated it was not required.
No further significant contamination was detected in the samples obtained from the natural soils underlying the fill and as the results did not indicate the presence of a significant hot spot beyond the limits of acceptable variation compared to the acceptance criteria, no further action was requested by the Auditor. The results of the Auditor’s check samples are included in Appendix G of this report.
12.7 ASBESTOS
Although asbestos is identified as a potential contaminant of concern on the site due to historical associations with gas plants, very few instances of potentially asbestos containing products were observed within the fill soils on the site, as noted in Section 4.6.11 of Enterra’s report. As virtually all the fill soils present were excavated during the conduct of the remediation within Area A, it is considered extremely unlikely that buried asbestos wastes could have remained undetected anywhere on the site, and none was indicated by the earlier boreholes and investigations prior to the remediation excavations.
Similarly, there was no evidence of loose fibrous asbestos materials noted in the excavated fills or contained within the wastes uncovered by the excavations. No analyses for asbestos fibres have therefore been undertaken on the excavated or re-used soils by Enterra or during the earlier investigations on the site, and were not considered necessary by the Auditor based on the observations made of the site as it was excavated over the period of the remediation.
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13. ASSESSMENT OF REMAINING HEALTH AND ECOLOGICAL RISKS
13.1 POINT CONCENTRATIONS
Enterra in presenting the data relevant to soils remaining on the site, have sub-divided the gasworks site into a number of domains that have similar historical usage. This allows statistical analysis of the available data without the volume of data being such that individual exceedences are overlooked.
The four domains relevant to Area A of the site are as follows:
Domain A1 – the north eastern quadrant – including validation tests from a thin strip of land ultimately included in Area B following a change in the indicated location the A/B line separating Area A from Area B
Domain A2 – the south eastern quadrant – also including a thin strip of land ultimately part of Area B following adjustment of the A/B line.
Domain A3 North – the north western quadrant
Domain A3 South – the south western quadrant
The locations of these Domains are indicated in Enterra’s Figure 5 and have been summarised on Dames & Moore’s Figure 3 of this report.
The concentrations of contaminants that remain in the soils at the base of the excavation following removal of the highly contaminated waste soils are summarised in Enterra’s Tables 1 and 2 for the soils at the base and 0.5metres below the base respectively. Table 3 indicates concentrations in the walls of the excavations.
Only isolated exceedences of the acceptance criteria remain following removal of the soils. The location and type of exceedence are indicated in Enterra’s Figure 8 for each of the Domains. The peak concentrations that remain (in those isolated cases) together with the 95% UCL calculated for each contaminant in each domain, are summarised in Table 13.4a at the end of this Audit report in comparison to the relevant NEPM guideline investigation criteria and the Site Acceptance Criteria established for the site based on the Egis risk assessment.
Table 13.4a summarises the exceedences for all domains. This review indicates that, whilst the relevant EILs from the NEPM for arsenic, chromium, copper, lead, nickel and zinc are exceeded by some of the peak concentrations, and for chromium by the 95% UCL, none of the NEPM D or E health investigation levels appropriate to high density residential and open space use are exceeded. The D1 or D3 target criteria are also not exceeded for any of the metals.
For Benzene the D1 & D3 criteria are only exceeded in a few isolated peak concentrations of up to 11mg/kg in Domain A1 and 8.2mg/kg in A2. The UCL 95% is however, well below the acceptance criteria for benzene over the whole of Area A, including the NEPM health investigation levels relevant to Open Space and High Density Residential.
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In no case does cyanide exceed relevant NEPM health investigation levels or the acceptance criteria for the site. Phenolics were not found to be significant in the latter investigations prior to the remediation or in the stockpiles of excavated soils and were not included in the validation program. Cresols were detected in the reused treated fill soils, but are within D3 criteria for re-use.
Some peak concentrations of Ammonia do exceed the D1 criteria. However, this was based mainly on concern about odours and ecological risks and the UCL 95% is within the selected criterion of 500mg/kg agreed with Egis. Ammonia is discussed further in relation to groundwater quality.
PAHs, in particular Benzo-a-Pyrene (BaP), were expected to be the main concern regarding validation of the site. The most significant individual PAH was naphthalene. However, although peak concentrations of BaP did in a few cases exceed NEPM D & E concentrations of 4 and 2 mg/kg, and in a few cases the D3 criteria, only in Domain A3 at up to 3.9mg/kg did the 95% UCL exceed the lower of the criteria – NEPM E level of 2mg/kg. The 95% UCL for the remaining in-situ material is therefore well within the acceptance criteria for the site. Similarly, although there were some exceednces of the D1 criteria in total PAHs, which would be interpreted to be mainly naphthalene, again the 95% UCL was well within the acceptance criteria.
It must be noted therefore that there is some potential for some remaining odour in the natural soils at depth as a result of the PAHs and ammonia that remain present.
In terms of the soils re-used, only the re-used treated soils have been reviewed in detail as the imported fills all fall within “fill material” guidelines. These are summarised in Table 13.4b. The re-used treated fine soils show peak concentration exceedences for the same metals as for the base samples. They also contain a proportion of TPH that exceeds the D3 acceptance criteria for a few individual samples. The 95% UCL indicates that statistical examination of these analyses results in upper confidence levels that are within most of the criteria and do not exceed relevant D1 or D3 acceptance criteria or that the maximum concentrations recorded for the site do not exceed D3 thus making further analysis unnecessary.
PAHs remain the most significant chemical in relation to the management of these soils with a few peak concentrations exceeding D3 criteria. However, the 95% UCLs for total PAH and for BaP, although exceeding D1 criteria, remain at concentrations of 282mg/kg and 18.2mg/kg, sufficiently within the D3 criteria of 500 and 25 mg/kg for total PAH and BaP respectively.
Therefore, although the re-used soils remain contaminated, as they were only used in the context of D3 class of material, they fall within the parameters considered acceptable for that use. The contamination levels also have the potential to create some groundwater contamination by the partitioning of the chemicals between the 2 media. However, the re-used soils also only represent some 10% of the material backfilled on the site, which reduces somewhat the capacity for those chemicals to be leached to groundwater in larger quantities. The remaining 90% of imported and clayey “Fill Material” provides local clayey soils that can to some extent re-absorb these chemicals into the soil matrix.
Because of the remaining presence of contaminated soils and the re-use of material classified as D3, the site is considered to remain contaminated and measures are required as conditions in the Statement of Audit for the site to ensure that the potential for re-exposure of these soils is minimised or, if re-exposure
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occurs, they are properly managed. A bright orange marker layer was also placed at the top of D3 classified re-used fill soils to identify where these soils occur.
Table 13.4c below references the deeper soils below the validated base of the excavation and summarises the data presented by Enterra in their Table 2.
Table 13.4c – Summary of Maximum Concentrations Detected Post Remediation in Sub-base Soils Chemical of Maximum Concentration Detected in D3 NEPM Potential Sub-base Samples Post Remediation Criteria E level Concern by Domains Criteria mg/kg mg/kg A1 A2 A3N A3S Arsenic 16 18 28 22 300 200 Cadmium <1 <1 <1 <1 50 40 Cobalt 43 19 20 34 500 200 Chromium 44 50 31 30 2,750 200 Copper 54 23 33 37 1,000 2,000 Mercury 1.6 1.4 2.8 1.1 20 30 (inorganic) Nickel 130 45 110 160 1,000 600 Lead 140 46 92 1000 3,000 600 Tin (inorganic) 4.3 5.2 12 10 500 - Selenium 5.2 4 3.6 3.1 100 - Zinc 140 150 250 410 5,000 14,000 BaP 7.3 18 3.9 10 25 2 Naphthalene 130 46 15 10 - 70** Total PAHs 330 420 44 81 500 40 Benzene 96.2 0.5 0.3 6 2** Toluene 1.7 15 0.1 0.05 20 Ethyl Benzene 9 0.7 2.1 0.6 10 Xylene 2.3 6 3.3 3.2 70 TPH C6-C9 170 44 10 10 1,000* TPH C10+ 1200 3400 690 1600 10,000* Cresols 0.2 9.7 <0.05 <0.05 25 Total Phenols 1.7 100 <0.8 <0.8 17,000 17,000 Ammonia 830 950 1100 450 500 Cyanide (total) 23.6 11 560 76 2,500 Sulphate 1900 1100 2400 1200 2,000 Notes * Based on EPA Fill Material criteria, ** Egis Tier 1 criteria
13.2 IMMINENT ENVIRONMENTAL HAZARDS
The Auditor is not aware of any imminent environmental hazards that are associated with the subject site.
13.3 HUMAN HEALTH RISKS
In assessing the level of risk that may be incurred from the presence of any remaining contaminants in the soil of this site, human health risks associated with long term residence and the presence of children are the
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99 of 145 Report Revision 0 Environmental Audit, Area A – West Melbourne Gasworks February 2002 for Docklands Authority Page 96 most significant with regard to potential beneficial uses of the site, including sensitive uses. Risks to children under the age of 5 that are resident on the site are considered likely to be the most significant given the location of the site in a built up area now being zoned for residential purposes, whether or not part of the area is used for commercial development or open space.
For a residential setting, in the health risk assessments conducted for the site, the actual exposure potential for adult and child residents of the site in the future, is also considered likely to be less than for the most conservative residential case. Therefore, satisfaction of criteria similar to NEPM EIL or ANZECC threshold investigation soil criteria as target criteria for the site was considered to be conservative.
This argument is also supported by risk based investigation levels that have been developed by the National Environmental Health Forum (NEHF) and incorporated in the NEPM ‘Assessment of Site Contamination’ for a typical residential scenario (A Levels) and for a medium to high density scenario (D Levels) which are based on a relatively conservative assessment of the potential for exposure of adults and children, and also generally on 100% bioavailability of contaminants.
The available data reviewed in the Enterra report, although limited to some extent in terms of the location of materials replaced on the site, suggests that exposure point concentrations for this site are unlikely to exceed the acceptance criteria that have been adopted for this audit. The fill soils and underlying natural soils, which are most likely to be sources of exposure to future residents, have exposure point concentrations generally below the NEPM HIL ‘D’ for high density residential use and in some cases below E levels for public open space. They are therefore considered to be acceptable in this context.
The health risk assessments undertaken, that include consideration of the proposed high density residential setting, generate acceptable concentrations of potential contaminants that are similar to or significantly greater than the limiting values for investigation criteria indicated in the NEPM HILs.
The Auditor therefore agrees with the conclusions of Enterra in their report that the condition of the site is acceptable for future development for sensitive uses, but limited to high-density residential use, or to commercial or general (passive – non-recreational) open space use. It is considered that the risks to human health from the levels of chemicals remaining on the site at the time of the investigation and testing are acceptable in the context of the proposed use of the site for limited sensitive uses.
Based on the available groundwater data and the modelling studies and risk assessments undertaken that took into account the site history, the nature of the fill materials and the underlying clayey and silty soils, the potential sources and concentration of contaminants and the estimated depth to groundwater, and the relevant beneficial uses of the groundwater on the site, it is also considered that the contaminant levels detected in the groundwater are unlikely to constitute a health risk at the site.
Relevant beneficial uses of the groundwater and associated risks are discussed in Section 13.5.
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13.4 ENVIRONMENTAL RISKS
13.4.1 Potential Pathways for Migration of Contaminants
The pathways for migration of any potentially mobile contaminants in clay soil materials to groundwater or laterally to Victoria Harbour or the Yarra River are considered to be constrained by:
• The moderate concentration of the contaminants that remain within the bulk of the soils (90%) replaced on the site following remediation, generally below concentrations commensurate with “Fill Material”;
• The low permeability of the natural silty clay sub-soil horizons of the CIS beneath the whole site;
• The depth to the deeper groundwater aquifers;
• Restricted infiltration from rainfall because of high annual evapo-transpiration potential and uptake by vegetation and eventual coverage of a large proportion of the site by development; and
• The tendency of the natural clays to encourage absorption of mobile chemicals.
Similarly, the potential for migration of chemicals via surface run-off from the site, or by migration through the surface fills, is anticipated to be insignificant due to the mainly low concentrations of chemicals detected in the surface soils. Where there remains some potential for mobilisation of the chemicals that remain in the re-used material, this is limited by the clayey soils used and to a large degree has been minimised by the stabilisation of these materials with lime used in the treatment process.
13.4.2 Discussion of Ecological Risks
Samples included in the validation of the base of the remediated site and some of the re-used soil material included significant concentrations of metals and organic compounds, primarily PAHs. These exceed in some cases the acceptance criteria for the site, for individual samples. However, in most cases, 95% Upper Confidence Limit of the average concentration, is below relevant NEPM EILs.
In all cases, the recorded concentrations are within the D3 site specific acceptance criteria, except for a few isolated concentrations of TPH and PAHs. The Egis risk assessment considered the D3 criteria in relation to potential for attenuation of the contaminants were they are leached out of the soil and migrate to the nearest receiving waters. This was examined in terms of the concentration that would be considered acceptable compared to relevant ecosystem criteria (originally the ANZECC 1992 criteria). The potential for migration of the remaining contaminated material has also been somewhat reduced due to the presence of up to about 10% lime and appears to represent a minimal risk with regard to potential to migrate and impact on receiving waters.
The presence of the contaminants in some cases exceeds relevant phtyotoxicity criteria and should be considered unsuitable for some sensitive plants. This should be managed by the use of suitable imported soils in areas where landscaping and establishment of deeper rooting larger shrubs and trees may be required.
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In summary, the concentrations of contaminants that remain on the site are considered to represent low risks to flora and fauna in the area and as may be associated with the proposed high density residential land use, public open space and commercial uses of the Victoria Harbour Precinct. Therefore the environmental risks to plants or local fauna populations and domestic animals are considered to be acceptable.
13.5 GROUNDWATER RISKS
A large number of monitoring bores have been constructed at various times and for various purposes both on the former West Melbourne Gasworks site and in the adjacent land comprising the remainder of Victoria Harbour Precinct, and some land to the east of the Precinct that also forms part of the Docklands development.
In assessing the risks to groundwater in terms of existing and likely beneficial uses a number of studies have been undertaken before, during and after the remediation of the site. Remediation is also continuing on Area B of the site, and is anticipated to take place in the remainder of the Victoria Harbour Precinct over time, and therefore care has been taken to examine the data and relate it to the current condition of Area A, and to the likely risks that relate only to that portion of the site since completion of remediation of Area A.
In this regard, the most relevant bores are those constructed on Area A itself, and those constructed in the adjacent remediated areas of the Gasworks Site, as these give the closest picture of the current condition of the groundwater, although as discussed elsewhere this is also expected to change over time. The locations of monitoring bores on the site relevant to Area A are shown in Figure 3.
The current status of the groundwater has also been summarised in the prior submission to the EPA titled “A Submission to the Environment Protection Authority on the Practicable Extent of Clean-up at Area A – West Melbourne Gasworks Site, Melbourne Docklands” Dames & Moore report ref 37858\005\report\Extent Pract Area A Rev B 0.doc, dated February 2002. This report is included in the CDs attached to this Audit Report.
Deciding on what is a relevant beneficial use for the groundwater in each aquifer on the site is a complex matter as it depends on the current quality of the groundwater and the remediation status of the area into which the various bores have been placed, together with the extent to which recharge of the site has taken place since completion of backfilling.
It is also acknowledged that the quality of the groundwater is likely to change over time. The Egis risk assessment assumed that, although the shallow groundwater in Area A may also be remediated as a result of the soil clean up, the presence of a proportion of re-used contaminated soil could result in some recontamination of the local groundwater that they come into contact with. Many of the acceptance criteria developed for the site took into consideration the attenuated concentration of the COPCs that ultimately may reach the receiving waters in relation to ecosystem criteria relevant to those waters.
Figure 6 of the Enterra Groundwater Report shows the Monitoring Wells available on the whole of the Gasworks site as at July 2001, and the graphs they have provided in their report show the fluctuations in concentration of contaminants in the bores used for monitoring over the period of the contract.
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The relevant bores to this assessment of groundwater risk are tabulated in Tables 13.1 to 13.3 below. These tables summarise the available bores that are located within the remediated areas of the site, and the adjacent areas outside Area A in unremediated soils for each of the three main aquifer groups, the shallow fills, the Coode Island Silt/Fishermens Bend Silt, and the Morary Street Gravel Aquifer.
Table 13.1 Location of Monitoring Bores in Fill Relevant to Area A
Fill Aquifer Borehole No. Location Distance from Boundary Fill Bores Located On Remediated Site Or Adjacent To A/B Line MW 18A Western Boundary of Area A NA MW 19A Northern Part of Domain A2 on Area A NA MW 21A Eastern Boundary east of A/B Line 20m east Fill Bores Located Off-Site Adjacent to Area A MW 350A North West of North Boundary 20m north MW 415A South of South Boundary 20m south Fill Bores Located Off-Site At More Than 100metres from Area A [MW5A] North West of North Boundary 150m northwest [MW 345A] West of Western Boundary 140m west
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Table 13.2 Location of Monitoring Bores in CIS/FBS Relevant to Area A
CIS/FBS Aquifer Borehole No. Location Distance from Boundary Fill Bores Located On Remediated Land On Site Or Adjacent To A/B Line MW 19B Northern Part of Domain A2 on Area A On site MW 17B Northern East Boundary east of A/B Line 5m east BH 44 Eastern Boundary east of A/B Line 30m east MW 21B Eastern Boundary east of A/B Line 20m east MW 22B South East Boundary east of A/B Line 30m east Fill Bores Located Off-Site Adjacent to Area A MW 417B South East of South Boundary 10m south MW 415B South of South Boundary 20m south MW 422B South West of South Boundary 20m south MW 350B North West of North Boundary 20m north MW 353B North East of North Boundary 20m north
Table 13.3 Location of Monitoring Bores in MSG Relevant to Area A
Moray Street Gravel Aquifer Borehole No. Location Distance from Boundary Fill Bores Located On Remediated Site Or Adjacent To A/B Line MW 19C Northern Part of Domain A2 on Area A NA MW 21C Eastern Boundary east of A/B Line 20m east Fill Bores Located Off-Site Adjacent to Area A MW5C North West of North Boundary 150m northwest MW 350C North West of North Boundary 20m north MW 353C North East of North Boundary 20m north MW 11C South East of South Boundary 40m southeast MW 4C South of South Boundary 40m south MW 422C South West of South Boundary 20m south
Tables 13.5a to 13.5c, located at the end of this Report, summarise the most recent available data for various available monitoring bores both on-site and off-site in each of the three aquifers on Area A, to allow comparison of the groundwater quality with relevant criteria.
A summary of the groundwater TDS values in relation to the SEPP segments are presented in Table 5.3 of this report and conclusions as to likely beneficial uses in Table 13.7 below.
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From the Egis study in 1999, it is known that no registered groundwater bores are located within 2.5km of the site except for groundwater monitoring bores. There are therefore no water supply bores on either the Victoria Harbour Precinct area or anywhere down gradient of the site within 2.5km and no existing beneficial uses of water extracted from the MSG or other aquifers. This is consistent with previous reviews of groundwater data undertaken by this Auditor for the Mirvac and Western Link Audits in which only a few shallow bores located in the Port Melbourne Sands were identified at some distance from this site in South Melbourne or Port Melbourne and which would have no hydraulic connection to the gasworks site.
No central database of bores has been made available for reference by Docklands, but monitoring bores located in shallow soils are known to be present on the MAB site to the north beyond Victoria Harbour, and to the south beyond the Yarra River. These also are not in hydraulic connection with the shallow fill soils on the Gasworks site and therefore not relevant to this analysis.
As discussed in Section 9 above, the TDS of the groundwater detected in the boreholes constructed by Egis and Enterra both on and off-site, is in the range 1,100 to 30,000mg/L in the shallow fill aquifer, depending on where they are located on the site. The lowest recorded TDS is from borehole MW18A, located in the remediated soils and impacted only by recent infiltration of rainwater and therefore although it could theoretically therefore be classified as Segment B – Agriculture Parks and Gardens, however, MW21A, located 30 metres into Area B of the site, but also in remediated soils has a TDS of 4,700mg/L, and therefore the lower TDS is considered unrepresentative of its likely final condition once groundwater has reached equilibrium with the soils. The average TDS value is in the range 3,000 to 7,000 mg/L for the majority of the fill material on the site, although this is also the unremediated fill.
For the CIS/FBS soils, the TDS for bores on or within close proximity of Area A, generally is in the range 3,800mg/L to 28,500mg/L, with most exceeding criteria for Segment C. As indicated in Table 5.3, all of the MSG bores indicate TDS exceeding 19,000mg/L and fall within Segment D.
It is evident from the discussion in Section 10 of this report, that utilisation of the criteria derived from the Egis risk assessment would leave the site to some extent contaminated, even though at least 90% of the backfill soils could be considered to fall within a “Fill Material” classification.
In order to formulate the soil criteria for the site discussed in Section 10 where there was a potential for ecological risks, Egis back calculated from concentrations that would emerge from groundwater into receiving surface waters indicated in the relevant SEPP for Yarra Waters (then in a draft form) or where not covered by the SEPP, from ANZECC 92 Australian Water Quality Guidelines for Fresh and Marine Waters. They allowed for natural attenuation processes without sorption over the 60 metres distance through the fills to the Yarra River, the nearest receiving waters south of the site, including Area A. The resultant concentrations for the selected chemicals modelled by Egis are summarised in Table 13.6.
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Table 13.6 – Summary of Results of Egis Analysis
Chemical Reference Indicator Derived Derived Soil at Yarra River Groundwater Concentration Draft SEPP (1995) Concentration at Site Boundary mg/L mg/L mg/kg Ammonia 0.008* 0.008 500 (total) (Unionised) Benzene 0.3 7.5 80 Toluene 0.3 29,000 587,250 Ethyl Benzene 0.25 260 6,090 Xylene 0.25 52.5 2,700 Benzo-a-pyrene 0.00015 0.0015 90 Phenols 0.05 45,000 378,000
The concentrations allowed in the final criteria accepted for the remediation of the site also took into account other factors such as odour, and final concentrations in soil horizons were mostly well below the concentrations indicated for the soils. Ammonia is also present as a background concentration in all of the aquifers beneath the site and could not be calculated by Egis. No analysis was undertaken for metals as they were not anticipated to be key contaminants within the material to be remediated.
Information regarding the contamination status of the site groundwater after remediation was sourced from the series of monthly Groundwater Monitoring Events (June 2001 to January 2002, Enterra) incorporated into the updated groundwater report CD provided by Enterra. In this Audit report, the analytical results are compared with the SEPP Waters of Victoria (Schedule F7 – Waters of the Yarra), Ecosystem Support Marine ANZECC (1992) values, Raw Water ANZECC (1992) and other relevant criteria. Exceedences of the adopted criteria are highlighted in Tables 13.5a to 13.5c for the three aquifers – Fill, CIS/FBS and the MSG. Each table includes both relevant on-site bores located in remediated areas, including some in adjacent areas in Area B, and bores located off-site in unremediated soils in the remainder of Victoria Harbour Precinct.
To assist the process, in Tables 13.5a to c, the relevant SEPP and ecosystem criteria are separated from a second comparison with all other relevant criteria. The exceedences of relevant criteria are discussed below.
Although non-aqueous phase liquids (NAPLs) were removed from parts of Area A during the remediation process, some NAPLs do remain on the adjacent Area B of the site and are subject to a separate submission to the EPA. The Auditor’s opinion of the risks presented to Area A from this remaining off- site source is that they are considered to be acceptable, which is discussed in the modelling and risk assessment report provided with this submission for reference.
The State Environment Protection Policy (Groundwaters of Victoria) provides a guide for potential beneficial uses of groundwaters by allocating groundwater to five Segments which are defined by total dissolved solids (TDS) content of the groundwater. Using the range of groundwater data provided in the Site Validation Report – Area A – Groundwater (Enterra October 2001), and in information provided in
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Groundwater Monitoring Events subsequently, the range of potential beneficial uses have been identified for each aquifer as indicated in Table 5.3 above.
On the basis of Table 5.3 and taking into account other factors such as yield and the location of the site, the beneficial uses summarised in Table 13.7 were considered likely.
Table 13.7 Existing and/or Likely Beneficial Uses on Area A
Potential Beneficial Existing Likely Comments Use
Potable Water / Potable NO NO No existing use of groundwater is recorded for the site or in Mineral Water the area, and the low anticipated yields makes it unlikely that it could be developed as a water supply source. TDS is also unlikely to be acceptable for a potable use in the Fill, and is too high to be considered in the CIS/FBS and MSG.
Agriculture Parks & NO NO Although localised improvement of the fill aquifer may occur Gardens (irrigation) due to seasonal infiltration of rainwater into the fill, the potential yield, limitations on recharge in the completed site, and a likely increase in TDS over time, makes it unlikely that groundwater would be used for local irrigation of gardens or landscaped areas on the site. TDS is also too high for CIS/FBS or MSG to be a likely use.
Stock Watering NO NO Although a possible use for the Fill aquifer from TDS, this land will eventually be part of the Melbourne CBD with high density residential as the main land use which makes Stock watering unlikely. The low potential yield in the Fill and CIS/FBS, and high TDS in the CIS/FBS and MSG aquifers, also eliminates this as a likely or relevant beneficial use.
Industrial Use NO NO Industrial use is not considered to be relevant in primarily high value residential commercial suburb on site. Low yields from the fill and CIS/FBS, and high TDS in the CIS/FBS and the MSG, also make it unlikely to be used from any aquifer. Water high in TDS from the MSG could be extracted in South Melbourne within 350metres of the site, but is not considered to be a relevant beneficial use as the high TDS makes it only suitable for one time cooling use which is only relevant to the power generation industry. There is also nowhere to dispose of surplus extracted water except directly into Port Phillip Bay where the temperature increase would likely exceed relevant SEPP indicators.
Primary Contact YES YES In terms of the SEPP, this is a relevant and likely beneficial Recreation use in the Yarra River and Victoria Harbour – for the CIS/FBS and fill aquifers, (but not for the MSG aquifer which does not daylight in adjacent receiving waters). The Fill aquifer and CIS/FBS is unlikely to be used for extraction of groundwater to fill pools etc, due to negligible potential
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yields, but the MSG could be so used for salt water installations. This has been considered.
Buildings & Structures NO YES Beneficial use in relation to structures in the primarily high profile residential/commercial in the area is relevant. Groundwater in all aquifers will be encountered by deep piled footings required for supporting large buildings over the soft CIS soils.
Maintenance of YES YES The Yarra River is 60 metres south of the site, and Ecosystems Victoria Harbour 150 to 200metres to the north. Local gradients at the site are variable. This is therefore considered existing and likely for the Fill and CIS/FBS aquifers, although low permeability in the CIS makes migration to receiving waters unlikely to be significant. The potential impact from residual contamination in the Fill was considered in the Egis risk assessment.
For the MSG, although gradient is currently southwards towards the Yarra, it is considered unlikely to intersect with the receiving waters until several kilometres to the south in Port Phillip Bay and is therefore impact on receiving waers isnot considered likely with regard to Area A.
13.5.1 Fill Material (A Wells)
Typically TDS values for the remediated areas lie within Segment C. This is based on the values for bores located in fill material that are mainly yet to be remediated. There have been three monitoring bores re- established on the site since completion of remediation. More have been requested by the Auditor to allow long term monitoring of the groundwater recovery in the fill layer but are not yet available. Of those that have been installed to date, monitoring bore MW19A, and subsequently MW18A, were subsequently found to be dry following remediation and backfilling of Area A, whilst MW21A located on the boundary with Area B indicates a TDS appropriate to Segment C.
It is possible that initial recharge of the fill aquifer could also be considerably fresher in some areas as indicated by initial samples from Monitoring Bore MW18A with a TDS of 1,100mg/L. MW18A is located within the remediated backfill. This lower TDS which potentially indicates segment B, may be from dilution by recharge from rainfall subsequent to the remediation.
The most recent analyses in January 2002, found that both MW 18A and MW19A were virtually dry and insufficient water remained for sampling. Field testing of the residual moisture in each bore indicated the TDS of what remains to be closer to 1,800mg/L. MW21A in the remediated area of Area B indicated a TDS in the range 4,000mg/L to around 6,000mg/L in recent analyses. It is therefore considered that Segment C is the most appropriate for the Fill Aquifer.
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The water from the fill also exhibited a raised pH above 10 in both MW21A and MW18A. This appears to be due to the use of lime both to assist in remediation of the soils, and as a stabilising agent to reduce moisture content and assist in compaction. For treatment, lime was used up to as much as 10% by weight, and for compaction, a rate of 3 to 5% is normal practice by civil engineers. Previous investigations by this Auditor into lime as a hazard on a site audited at Preston, indicated that, due to its buffering capacity, the pH of lime treated soils tends to stay above pH10 and can be in the region of pH12 until virtually all of the lime has converted by oxidation to the carbonate form, when the pH drops rapidly. Exposure of the soils again to the air at the surface, would be anticipated to trigger this reaction and the pH rapidly reduce as a result. It is therefore unlikely to be a hazard to the quality of stormwater run-off from the site. Study of the effect of lime in groundwater at the same site in Preston, indicated that the pH was normal within 3 metres of a quarry that was filled with lime waste for more than 50 years and it was concluded that the presence of concentrations of lime remaining on that site were not a risk to the environment or to groundwater. Lime is also not toxic and not a health risk except that large clumps of unreacted lime can cause burns if it comes in contact with mucous membranes.
It also appears unlikely that the transitory nature of the groundwater in the fill on Area A would provide sufficient yield for groundwater use. The area and volume of the fill and recharge capacity appears to be somewhat limited and the compaction and addition of stabilising agents to the compacted imported fill would also have reduced permeabilities to very low levels. It therefore could be considered to have insufficient yield for most potential uses. Attempts to develop the groundwater, if any is found within the fill, would also be expected ultimately to intersect water with TDS similar to the original quality from surrounding areas and, possibly, from Victoria Harbour. Therefore, it is considered that Segment C is the most appropriate classification for the fill material if any is used.
Segment C is relevant to maintenance of ecosystems, stock watering, industrial water use, primary contact recreation and building and structures. The only uses unique to Segment B if that were to be considered, is Agricultural Parks and Gardens – ie irrigation use, or potable mineral water.
13.5.2 Coode Island Silt/Fishermens Bend Silt (B Wells)
TDS values within the CIS or FBS generally lie within Segment D of the SEPP. All of the on-site bores that remain on Area A or adjacent areas of Area B, located in CIS post remediation, indicate TDS not less than 13,000mg/L. A few of the off-site bores located in this horizon indicated potentially lower TDS (MW350B, 353B and 415B). However, these remain in soils below unremediated fill outside the site and may be partly influenced by seasonal inflows of rainwater, as they also have a wide range of TDS up to maximums of 25,000mg/L.
Segment D beneficial uses that should be considered include maintenance of ecosystems, industrial water use and buildings and structures.
Yield would also be an issue for the CIS or FBS, generally considered to be aquitards rather than aquifers. Table 5.2 above indicates the results of field tests that confirm the very low vertical permeability and low horizontal permeability of these formations. Although, some more permeable sandy layers could exist within the formations, none were noted on Area A of the site. Therefore, it is considered that insufficient yield should eliminate the CIS/FBS formations from further consideration as an aquifer.
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13.5.3 Moray Street Gravels (C Wells)
All arithmetic average TDS values for the C Wells lie within Segment D. Segment D beneficial uses include maintenance of ecosystems, industrial water use and buildings and structures. The yields in the MSG would be expected to be good if developed as an aquifer.
13.6 GROUNDWATER QUALITY IN AREA A
13.6.1 Ammonia
The Egis risk assessment did not adequately deal with the presence of ammonia. However, if the results summarised in Tables 13.5a to 13.5c are examined, it is apparent that ammonia is present throughout all formations and all locations on and off the site, both up-gradient and down gradient. The concentration in the MSG aquifer is particularly uniform whether up-gradient or down gradient. (See figure 5H of the Enterra Groundwater Report).
Ammonia is a “chemical of potential concern” (COPC) on the gasworks site due to its presence as a by- product, although the ammonia plant was located on Area B of the site adjacent to what is now the GRS. However, the concentration in the MSG falls in a narrow range of 24 to 81mg/L. The ammonia also occurs throughout the CIS at concentrations of 4 up to 110mg/L, and in the overlying remediated fill at 24 to 110mg/L. It is also known to be present at similar concentrations within the CIS over much of the Yarra Delta and was encountered in bores for the Western Link and other parts of Docklands.
It appears therefore that the presence of the ammonia is endemic to the Yarra Delta formations and is largely a background concentration derived from the breakdown of organic matter incorporated into the more clayey estuarine environments at the time of deposition of the CIS formation. The ammonia in the CIS is therefore probably also the main source of ammonia in the adjacent aquifers, although anthropomorphic sources such as sewage effluent leakage into the various aquifers from off-site sources could also be contributing as past contamination on the gasworks site may also have done.
Rick Graham also examined in the 1994 audit report the potential release of ammonia to Yarra River. He estimated a potential concentration of up to 10micrograms/L of total ammonia equivalent to 0.12 micrograms/L of unionised ammonia, assuming a concentration of up to 100mg/L in the groundwater. It was his opinion that this was small in comparison to the 0.008mg/L of unionised ammonia then applying as an indicator in the relevant SEPP.
The revised schedule F7 of the SEPP now allows 0.02 to 0.03mg/L of unionised ammonia to enter the Yarra in the upper estuarine segment, where modified ecosystems are also likely. This is equivalent to a total ammonia concentration in the receiving waters of up to 2.2mg/L as indicated in the ANZECC 1992 Guidelines assuming pH in the range 6.5 to 7.5 and temperature around 10 to 15 degrees. This would drop significantly where there is a high pH such as indicated in the compacted fill.
On this basis, with concentrations in the formations up to 110mg/L on Area A, of the same order that Rick Graham considered, it is considered that the presence of the ammonia is unlikely to impact adversely on established local ecosystems and is not important to the maintenance of the ecosystem. Removal of the
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For the remainder of the concentrations of chemicals that remain in the various aquifers, potential impacts on likely or existing beneficial uses are considered in the following sections.
13.6.2 Maintenance of Ecosystems – Existing and Likely
Maintenance of ecosystems is a beneficial use of the groundwater at the site that has to be protected. The current status of the groundwater in the various formations beneath the site is summarised in Table 13.5 at the end of this report. The concentrations detected in monitoring bores located on and around the site are compared to the SEPP Schedule F7, Waters of the Yarra, and to other relevant ecosystem criteria.
Fill Aquifer
As indicated in Table 13.5, there is potential for off-site exposure of ecological receptors due to groundwater contamination from the fill layers. Due to the removal of the original bores located within Area A during the remediation phase, only one bore of the two replaced onto the site, MW18A, is available for consideration of likely potential impacts from the remediated fill on Area A itself. MW19A was found to be dry during the groundwater monitoring events in July and August 2001, and MW18A has also subsequently dried out. MW21A is located on Area B. The remaining monitoring bores in the fill are located in unremediated fill soils outside the site and therefore are not necessarily representative of the condition of groundwater on the remediated Area A.
The following chemicals were found to exceed ecosystem criteria in MW18A during two rounds of testing in June/July 2001, after installation:
Selenium, Cyanide, pH, TPH, total PAHs and phenols.
As discussed above, Ammonia also exceeds criteria relevant to the SEPP.
The concentration of selenium in MW18A of 0.007mg/L, only slightly exceeds the SEPP Schedule F7 Waters of the Yarra, NEPM for freshwater and ANZECC 2000, marine guideline protective of 95% of species, all of which are 0.005mg/L. Therefore it is considered that natural attenuation over the 60metres to the Yarra is highly likely to reduce concentrations well below any that may impact on receiving waters.
The cyanide concentration of 0.6mg/L at MW18A exceeds the SEPP and other criteria by about 2 orders of magnitude. This may relate locally to soil concentrations of cyanide in the A3 north of up to 1200mg/kg in the re-used material, that is about half of the 2,500mg/kg D3 criteria. Similar concentrations of cyanide are also present in most of the fill monitoring bores, and up to 1.5mg/L in MW21A, located in the remediated fill in Area B, and therefore may represent a risk to ecosystems. From the Egis risk assessment, it was anticipated to break down rapidly and attenuate in the environment and the D3 criteria was developed on that basis although no intermediate groundwater concentration was reported.
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Total PAHs in MW18A on the site, at 0.38mg/L, exceed NEPM criteria by about 2 orders of magnitude as does the 0.68mg/L in MW21A, indicating that PAHs, probably mostly naphthalene, are also present. However, BaP has not been detected in any of the fill bores and therefore is not considered to be an issue.
Other metal contamination exceeds ecosystem water quality objectives at the Yarra River (the SEPP Waters of Victoria – F7 – Yarra River) and/or the 2000 ANZECC/ARMCANZ Australian Water Quality Guidelines for the Protection of Aquatic Ecosystems, also the detection limits applied were greater than the SEPP indicators for cadmium, copper, lead and mercury. None of these metals were detected in the groundwater remaining on Area A (MW18A). However, in the bores located outside the site and in MW21A exceedences included the metals cobalt, chromium, lead, manganese, nickel, selenium and zinc.
Ammonia is present in most of the bores at concentrations between 6 and 15mg/L off the site, but also up to 110mg/L in MW21A. As this is a total concentration, this was compared to 2.2mg/L indicated in the 1992 ANZECC ecosystem criteria as appropriate for total ammonium ions, at pH of 7 to 7.3 and temperature of 10 to 15 degrees Celsius of the receiving waters. A low concentration of phenolics was also noted in the on-site bores.
TPH was detected at 2mg/L in the C10+ range in MW18A. This is compared to the NSW petrol station criteria which is suggested to be 10mg/L based on the inferred minimum dissolved concentration that could be generated where visible oil may be noted on the groundwater. This is appropriate for consideration of ecosystem criteria such as the SEPP as it requires there to be no visible floating oil or grease. Benzene is considered separately.
BTEX compounds were not detected in MW18A on Area A, but was found to be present in MW21A about 20metres east of the A/B line. The later sampling of MW21 in July 2001 and January 2002 indicated that these concentrations dropped below 1mg/L, although the benzene concentration still exceeds the Schedule F7 indicator by 3 orders of magnitude. However, this is not on Area A of the site and appears to be localised in deeper fills in that part of Area B and is considered separately with that Area. [The Benzene has been separately considered for Area B with regard to human health risks (related primarily to inhalation) in the Auditor’s risk assessment, where a dissolved concentration of 2.3mg/L of Benzene in groundwater at 1.5metres depth, was considered to be the cut off point for residential or commercial and open space use of the land.]
In summary, the one sample of groundwater from the fill in the remediated areas of Area A, contains relatively modest concentrations of contaminants and that the two samples taken before the water levels dropped below the base of the fill indicated a trend of reducing concentrations of contaminants. However, based on all of the bores in the remediated areas, the concentrations of the metals and other contaminants detected may exceed ecosystem objectives generally by between 1 and 2 orders of magnitude, and the pathway to the Yarra is relatively short at about 60 metres in the assumed down gradient direction. Attenuation of the metals in the clayey fill soils is anticipated to occur as a result of absorption onto the structure of the clay particles in the soils and by dispersion within the aquifer. Migration rates are also likely to be relatively slow as evidenced by very low ingress rates of water into the excavations during the remediation work, and subsequent re-hydration of the fill, although the variable nature of the imported fill is also more erratic in this regard.
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It is considered that, based on the Egis risk assessment, concentrations of contaminants reaching the Yarra through the fill aquifer are unlikely to be significant in relation to ecosystem criteria. However, there remains some potential for the ecosystem to be impacted and groundwater management and continued monitoring is a condition of this Audit Report to be included in a suitable site specific Environmental and Groundwater Management Plan.
There also remains some concern at re-contamination of Area A from the outside areas by free product and polluted groundwater. Clay cut-off walls were located on the boundary of the site to minimise the potential for re-contamination of the remediated site in this manner. The location of these clay bund walls is indicated on Enterra’s Validation Report Figure 10. The location of many of these walls in the anticipated down gradient direction for groundwater in the fill horizon, would also have the reverse effect after the water table has stabilised of minimising potential outwards migration from the site.
On balance, it is considered that there is no requirement for additional remediation of the Fill soils in Area A to protect Ecosystems, beyond what has already been achieved on the site.
It must be noted however, that as instructed in the EPA Guidelines, the earlier investigations by various parties and the validation testing by Enterra has indicated that gasworks wastes remain in soils adjacent to the former West Melbourne Gasworks site as defined in the Clean up Notice and addressed in this audit report. It is considered most likely that these areas of contamination represent previous undefined areas occupied historically by the Gasworks, rather than evidence of local migration from the audited areas. It is also understood by the Auditor that Docklands Authority is well aware of these wider areas of contamination and that they have been appropriately brought to the attention of developers occupying the remainder of the Victoria Harbour Precinct.
CIS/FBS Aquifer
With regard to the CIS/FBS aquifer, firstly it has extremely low permeability as indicated by Egis testing and later slug testing by Enterra in the FBS (see table 5.2), and therefore should not be considered an aquifer, rather an aquitard. From the testing undertaken, it would have extremely low to negligible yields and any transmission of contamination through the formation, both vertically or laterally, would be anticipated to be negligible as indicated by the modelling study undertaken for Area B.
MW 19B is considered to be the bore most representative of the CIS/FBS aquifer on the site, although MW17B, BH44, MW21B and MW 22B are also located in remediated soils on the Area B side of the A/B boundary. BH 44 is also somewhat closer to Gasholder 2 on Area B, and is potentially within soils impacted by long term contamination sourced from the Gasholder.
Contaminants that potentially exceed Ecosystem Protection Criteria in the CIS on the site (ie in MW19B) include:
Ammonia, Chromium, Cobalt, Copper, Lead, Manganese, Nickel, Selenium, Zinc, cyanide, BTEX, TPH >C9 and Total PAH.
BH44 and MW 21B contain benzene and other MAHs exceeding Yarra SEPP criteria. The rest of the suite of contaminants in the remediated areas, including chromium, cobalt, copper, lead, nickel, manganese,
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As discussed above, ecosystem criteria are significantly exceeded by the concentrations that remain in the CIS aquifer. However, studies on the permeability of these soils, and the results of the modelling and risk assessment undertaken for Area B for migration of dissolved phase contaminants based on these permeabilities, have indicated that the CIS and FBS layers are far less significant than the Fill layer with regard to the potential for lateral migration of contaminants in the groundwater.
Similarly, the extremely low yield of these formations makes the likely beneficial uses not relevant to the assessment of the environmental risks on this site. It is considered that there would be no net environmental benefit from attempting to remediate the CIS/FBS formations further to protect ecosystems in receiving waters.
MSG Aquifer
No TPH, MAH or PAH was detected within the MSG aquifer beneath or in the adjacent areas outside of Area A, except a transient concentration of total PAH, and up to 11mg/L of TPH (C10-C36) at MW11C on the south boundary of Area B. The source of this TPH is uncertain given the easterly gradient in the aquifer as indicated on Enterra’s Figure 5H in their Groundwater Report. It is possible that it comes from the unremediated areas of Victoria Harbour to the south of Area A and is therefore not an issue for this site. Recent (January 2002) data on MW11C of 0.3mg/L, confirmed that the concentrations detected in only the November GME, did not re-occur. It is therefore considered unlikely to be an ecological risk. This appears consistent with conclusions based on Egis investigations in 1999 on the potential for impact on the MSG aquifer from the more heavily contaminated parts of the gasworks site.
Metals were detected in the same suite as identified in the Fill and CIS, including chromium and selenium exceeding the SEPP in concentrations that are mostly less than an order of magnitude above the SEPP indicators, or for the remainder above relevant ANZECC criteria. Manganese exceeds ANZECC 2000 ecosystem criteria by up to 2 orders of magnitude. However, as the manganese is a naturally occurring mineral in the soils of the region and is present on and off-site and up and down gradient at similar concentrations, it appears to be a background concentration and unlikely to be linked to the Gasworks site.
Cyanide was also detected at up to 1 order of magnitude exceeding the SEPP criterion but is also widely spread across and outside the site. Cyanide can also result from natural processes or from other industrial processes than gasworks, such as metal hardening. Therefore, although it can be derived from contamination on the gasworks site, concentrations in the remediated soils were low and it is considered that the cyanide in this case may also represent mainly a background concentration in the whole area.
As discussed above, the range of ammonia concentrations is extremely consistent across the whole site in the MSG, including both up and down gradient of potential sources, confirming that it is likely to be a background concentration from naturally occurring sources in the CIS, rather than as a result of a source of contamination from Area A of the gasworks.
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Contaminants that potentially exceed Ecosystem Criteria in the MSG on the site therefore include: Ammonia, Chromium, Cobalt, Copper, Lead, Manganese, Nickel, Selenium, Zinc, Cyanide, TPH >C9 and Total PAH.
The MSG aquifer is not significantly contaminated in comparison to ecosystem indicators, and, as discussed in the Egis groundwater investigations, there is a long pathway, likely to be in excess of 2 kilometres, until it intersects with the receiving waters of Port Phillip Bay.
It is therefore considered that there would be no net environmental benefit in attempting to remediate the groundwater in the MSG Aquifer to protect ecosystems.
13.6.3 Primary Contact Recreation
Similar to the maintenance of ecosystems, concentrations of contaminants reaching the Yarra may exceed relevant guidelines regarding primary contact recreation. ANZECC 1992 provides guidance on Primary Contact which also references Raw Water criteria. These have been carried through into the ANZECC/ARMCANZ (2000) criteria for Primary Contact Recreation, which have therefore been referenced for comparison in Table 13.5. These are also relevant if the water is extracted for filling of swimming pools or fountains, however, due to lack of yield in the Fill and CIS/FBS, this is only considered relevant to the MSG aquifer.
As discussed above the CIS/FBS is unlikely to discharge at sufficient rate for any impact to occur on the receiving waters that would exceed Primary Contact Recreation Indicators.
The aquifers that are considered “likely” with regard to beneficial use for Primary Contact therefore are the Fill aquifer and the MSG, although seasonal variation in rainwater infiltration and the lack of yield could also make the Fill aquifer “unlikely”.
Comparison of the ANZECC/ARMCANZ criteria with MSG water quality, indicates that ammonia, chromium, manganese and selenium exceed the relevant indicators in the MSG bores that remain on the remediated site. Lead also marginally exceeds the 1996 (2001) NHMRC drinking water criteria in two bores in the MSG, and the Primary Contact/Raw Water criterion of 0.05mg/L in one off-site bore – MW4C with a concentration of 0.2mg/L.
The presence of ammonia would primarily be an aesthetic limitation due mainly to odour and adverse taste but is not likely to be a health consideration.
The results for the fill in remediated areas indicate the presence of metals arsenic lead and nickel exceeding NHMRC 1996 drinking water guidelines, ammonia, phenols and cyanide exceeding primary contact indicators and pH exceeding 10, also outside the range of 6.5 to 8.5. The high pH can limit the solubility of some metals (for example copper), but can also lead to increased mobilisation of the lead and arsenic.
The presence of benzene at 1.9mg/L was noted in MW21A, which is on Area A. This has also reduced in recent monitoring to below 1mg/L as discussed further above. No benzene or other BTEX was detected on the site in the active bore MW18A.
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It is also considered that the potential yield from the fill aquifer is unlikely to be sufficient for use of the water for filling of pools etc for the reasons discussed elsewhere and therefore is not considered to be a “Likely” use of this aquifer. The presence of the chemicals discussed above, would also restrict use of the aquifer for filling of pools on site if it were attempted.
Based on the results of the submission to the EPA on Clean-up to the Extent Practicable on the site, the EPA has in their response required that conditions be included in the Statement of Audit for the site related to ongoing management of groundwater pollution. Conditions are therefore included in the Statement of Audit covering this matter, together with recommendations on limiting the use of water for Primary Contact Recreation.
The concentrations within the fill aquifer are also considered unlikely to be sufficient at the boundary with receiving waters to be a risk for recreation activities in the Yarra or Victoria Harbour.
13.6.4 Buildings and Structures
Buildings and structures is a likely beneficial use of all aquifers on the site as piling is required for any building of more than one or two floors and basements may also be constructed.
The assessment of site history; inspections of the site; the review of potential contaminants of concern; and results of laboratory analyses, and the depth to groundwater, together indicate that the present condition of the site is unlikely to pose a risk of chemical degradation in the form of sulphate or chloride attack on buried concrete and unprotected steel. The concentration of sulphates is not significant, and although sulphides may be present in the CIS soils that are not yet oxidised to sulphates, it is considered that this is unlikely with regard to the remaining undisturbed CIS as it has remained saturated throughout the remediation.
Some point concentrations of sulphate in the re-used soils on the site exceeded the relevant acceptance criteria of 2,000mg/kg. However, the use of lime with the minor quantities of re-used CIS soils, both in treatment of the contamination and to aid compaction, is anticipated to have buffered those soils such that a reduction to an eventual acidic pH in solution is unlikely. The pH measured in the bores located in the re-used soils is also alkaline with a pH above 10, which confirms this assumption. It is therefore considered the quality of the groundwater is unlikely to impact on this beneficial use.
As a precaution, the Statement of Audit also includes recommending the use of acid sulphate resistant concrete to ensure that acid sulphate attack on the foundations at the site remains unlikely.
13.6.5 Industrial Water Use
As discussed in Table 13.7, this is not considered to be relevant in primarily high value residential commercial suburb on the site. Low yields from the fill and CIS/FBS, and high TDS in the CIS/FBS and the MSG, also make it unlikely to be used from any aquifer.
Water high in TDS from the MSG could potentially be extracted in South Melbourne within 350metres of the site which is potentially down gradient of the site (although existing gradients in the MSG indicate flow away from this area). This is also not considered to be a relevant beneficial use as, based on the
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ANZECC 1992 Guidelines, the high TDS makes it only suitable for one time cooling use, which is mainly relevant to the power generation industry. There is also nowhere to dispose of surplus extracted water except directly into Port Phillip Bay where the temperature increase would likely exceed relevant SEPP indicators and therefore would also not be feasible for these reasons.
Consideration of other uses as indicated in ANZECC 1992, indicates that the TDS is too high for industries where water of potable quality is usually required.
On balance it was considered that such a use in the area is unlikely, and is not relevant to considerations in the issue of the Statement of Audit.
13.6.6 Potential for Recontamination of Shallow Groundwater
Significant shallow groundwater contamination may also remain in the adjacent unremediated areas of the gasworks site, Area B, and in the surrounding areas of Victoria Harbour, that could impinge on the quality of groundwater beneath Area A. The contamination that has been removed from the soils previously located on Area A, or other parts of the Gasworks site, could also be considered a “source” of contamination that may have migrated off-site in the past. The groundwater modelling and health risk assessment undertaken by the Auditor for potential sources of pollution that may remain on Area B of the gasworks site after completion of remediation, has also been considered in terms of the potential to re- contaminate the soils and groundwater on Area A.
The potential for recontamination from sources that may remain within Area B, is considered in detail in the attached Dames & Moore report “Fate & Transport and Human Health Risk Assessment, Gasholder 1, 2 and Tar Pit, Former West Melbourne Gasworks Site, Docklands Victoria” reference 37858\005\report\FT&HRA_Rev0.doc, dated November 2001. This report models the possible migration of benzene and naphthalene from sources that may remain in the CIS/FBS soils at depth below former gasholder. The study assumed that groundwater would recover to approximately 1.5metres below finished level of the site based on the water levels measured in the fill prior to remediation. These levels are indicated in Figure 4.
The study concluded that concentrations of these contaminants in groundwater that may comprise a health or environmental risk, are unlikely to migrate from Area B of the site into Area A. This was considered for both the FBS/CIS and the replaced fill material, and is therefore considered not to represent a risk for Area A.
To limit the potential for recontamination from the unremediated portions of Victoria Harbour, clay bund cut-off walls up to 1 metre thick were also constructed on the boundary keyed into the underlying clay. The location of these bunds is indicated on Enterra Figure 10 in their Soil Validation Report.
13.6.7 Non Aqueous Phase Liquids
Section 18 of the SEPP “Groundwaters of Victoria” states that “where non aqueous phase liquid is present in an aquifer, it must be removed unless the Authority is satisfied that there is no unacceptable risk posed to any beneficial use by the non-aqueous phase liquid”. The excavations undertaken by Enterra appear to have removed the identified potential sources of NAPLs on Area A of the site.
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Some NAPLs may remain on the neighbouring Area B, and potentially in some of the unremediated parts of Victoria Harbour. The potential impact on Area A from the NAPLs remaining in Area B was considered to be negligible as discussed above.
13.7 GROUNDWATER AND SURFACE WATER QUALITY SUMMARY
From the discussion in Section 13.5 and 13.6 it is considered that there are potential risks if groundwater resources on or down gradient of the site were to be developed for likely beneficial uses, although there is no known existing use that may be impacted within 350metres of the site. There is also no hydraulic connection between the shallow fill soils and areas to the north, west and south. There is potential for impact on ecosystems in receiving waters, including the Yarra River and Victoria Harbour, and the aquifer quality is also considered unsuitable for contact recreation if the water is abstracted for that use, for example to fill swimming pools.
According to the SEPP – Schedule F7 (Waters of the Yarra) - the receiving waters fall into the Upper Estuary Segment of the Yarra. From Table 1 in Schedule F7, the segment is therefore considered to be a ‘highly modified ecosystem with some habitat values”. Also, although in the Upper Estuary Segment, Primary Contact Recreation (including water sports such as water skiing) is not a protected beneficial use, it is an intended beneficial use in the segment as from 2003. The concentrations that may be received at these waters should therefore also be considered in the light of promotion of the Dockland Area for recreational purposes and the intention to include this as a protected beneficial use from 2003.
The groundwater quality in all of the three ‘aquifers’ considered by this audit is relatively high in TDS, which also limits potential beneficial uses from extraction of the resource mainly to industrial use and buildings and structures, apart from maintenance of ecosystems. As discussed above, this is also considered an unlikely use due to the generally high TDS, and/or low yields. The MSG aquifer, which passes under industrial areas of South Melbourne, is the main candidate for industrial use due to the potential yields, and therefore was examined more closely in the Egis investigations. It also appears to be currently extracted on a significant scale for de-watering of a number of excavations to the south as the gradient is eastwards to south eastwards and the reduced piezometric level is approaching 1 metre below AHD in the south east corner of the gasworks site, although such use was not confirmed.
The MSG is also relatively isolated by the low permeability CIS from the mostly low concentrations of contaminants that remain on Area A, and also from the remaining potential sources of contamination, the gasholders and tar pit that have been removed from Area B. Monitoring has also indicated that migration of contaminants off-site in the MSG is unlikely to be currently occurring at significant concentrations, and only a modest concentration of TPH has been detected at one bore MW11C. The presence of ammonia is considered to be likely due to natural causes. For these reasons, it is not likely to be an issue for ecosystems due to the distance before the MSG aquifer intersects with the waters of Port Phillip Bay.
Industrial use appears to be unlikely within a reasonable distance from the site as the area is located more than 500metres from on-going industrial areas of South Melbourne, with the nearest industrial area to the South of Lorimer Street being about 350 metres from the site as discussed above. These distances also make it likely that attenuation through the MSG formation of any contaminants that may remain, would
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Consequently, this audit recommends that no extraction of groundwater for any beneficial use be undertaken from any of the aquifers on the site. If groundwater for a beneficial use was to be proposed on the site, the suitability of the groundwater for the proposed use should be reviewed by an appropriately qualified person such as an EPA accredited Environmental Auditor.
Post remediation, the site soils are contaminated with low concentrations of most of the metals and other compounds (PAHs, TPH, BTEX and cyanide and ammonia) detected in the groundwater, and therefore the site soils appear to have been the main source of this contamination. However, due to the mainly low concentrations of chemicals remaining in the shallow imported soils on Area A of the site, it is considered that the added contribution to surface and groundwater contamination of the region from Area A is likely to be negligible.
Based on the above considerations the environmental risks are also judged to be acceptable.
13.8 SOIL AESTHETICS
The Validation and Assessment Reports indicate the presence of some low concentrations of potentially odoriferous attributes of some of the soils at this site, particularly in the underlying natural CIS soils and re-used soils, although this was monitored by Enterra and the Auditor during the remediation process and noticeably odoriferous soils were not used as backfill.
The most likely soils that could have an odour are therefore the D3 class material at below 2 metres depth and some of the remaining natural soils at between 1 and greater than 5 metres depth. Management of any such soils would include limiting the potential for their re-excavation during later developments. No odour blankets were required by the Auditor to be placed on Area A to limit migration of odours to the surface as there were no indications that this was required.
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14. ENVIRONMENTAL MANAGEMENT STRATEGY
14.1 OBJECTIVES
The EPA has indicated in it’s letter of 21 February 2002, that “the Authority determined that polluted groundwater at Part A, West Melbourne Gasworks, Docklands, has been cleaned up to the extent practicable in accordance with section 12.2 of EPA Publication 759A of the “Environmental Auditor (Contaminated Land) Guidelines for Issue of Certificates and Statements of Environmental Audit”.
From the validation report provided by Enterra, and the Auditor’s assessment of remaining health and ecological risks on the site, it is the Auditor’s opinion that the remaining health and environmental risks are acceptable. However, the Auditor is of the opinion, and as noted by the EPA, that a number of contamination issues remain on the site that need to be managed appropriately.
As indicated in the conditions attached to the Statement of Audit, and as required by the EPA in their letter of 21 February 2002, a soil and groundwater management strategy must be developed for the completed development to put into effect the conditions and recommendations included in the Statement of Audit attached to this report.
The key to an effective long term management program for the site is, as part of the site Environmental Management Plan (EMP) to develop and implement appropriate protocols and procedures documented in a Soil and Groundwater Management Plan (S&GWMP).
The SGWMP should primarily aim to:
• define the responsibilities of all stakeholders with an interest in the site;
• limit the potential for re-exposure of significantly contaminated soils during development of the site;
• provide a protocol for the appropriate management of any contaminated soils that may be re-exposed during future deep excavations for developments or installation of services;
• provide a framework and targets for monitoring of groundwater at the site to confirm the results of the modelling and risk analysis;
• document the monitoring to confirm that potential post-remediation impacts on groundwater from adjacent areas of the site, or from on or off-site, do not jeopardise human health and are tolerable in the ecosystem, or minor and highly localised, or non-existent; and
• indicate thresholds that would trigger active management of groundwater at the site if required.
The strategy should build on the findings of the Auditor’s review in Section 13, and provide a framework for addressing the remaining land and groundwater contamination issues at the site through the future construction phases and thereafter with occupation of the site.
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14.2 SCOPE
The SGWMP should be developed to include at least the following items where there is potential to impact on the level of risk to humans living or working on the site, or to ecosystems.
14.2.1 Future Excavation Works
Future works may expose contaminated soils within the D1 class of material at shallow depth, or at the surface. Management of these soils and normal health and safety precautions in handling the soils should be considered by anyone employed on the site.
Similarly, excavations may extend beyond the 2 metre depth of the soil defined by the limits of the D1 criteria. This must be covered by specific management measures to prevent inadvertent spread of contamination, and must provide for appropriate health and safety precautions for workers and the public if such soils are to become exposed.
They must also provide for restriction of access to any excavations that are opened on the site below 2 metres depth for both safety reasons and to minimise potential for exposure of the public or of workers who are not appropriately trained or equipped to be able to undertake such work or to be exposed to the soils.
14.2.2 Groundwater Monitoring
Groundwater monitoring is required to be undertaken at regular intervals to confirm the findings of this audit and to allow prompt action to be taken to limit potential adverse impacts, if significant changes to groundwater concentrations occur or known areas of contamination migrate to areas where the concentrations may be an issue.
The location and type of monitoring bores should be designated in the plan and the frequency of sampling should be specified, together with ranges of concentrations for comparison with the monitoring results.
An initial period of monitoring is recommended to take place 3 months after completion of this audit, followed by 3 more monitoring events at 6 months, 1 year and at the end of 2 years. It is recommended that the results be reviewed by an EPA accredited auditor immediately after each event and any action can be recommended promptly, if needed. After 2 years, continuation of the monitoring can potentially continue at a reduced frequency. However, it cannot be ended until such time that remediation of the soils and groundwater takes place. The practicability of any such further remediation should also be considered on a regular basis in relation to available remediation technologies.
14.2.3 Groundwater Contingency Plan
As part of the groundwater management plan, a contingency component must be included to activate should concentrations exceed thresholds for one or more of the analytes in the monitoring bores.
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15. CONCLUSIONS
15.1 FINDINGS OF AUDIT
This environmental audit has addressed the environmental condition of a portion of the former West Melbourne Gasworks site known as Area A, which is currently owned by the Docklands Authority.
The site is unsuitable for the issue of a Certificate of Audit due to the presence of residual soil contamination in the soils and groundwater on the site including PAHs, TPHs, metals, ammonia, cyanides and sulphates and a Statement of Audit indicating the beneficial uses that are acceptable on the site is issued.
Site remediation works conducted by Enterra Joint Venture haves been completed within the scope of work anticipated such that the Auditor is satisfied that the site is suitable for the proposed uses within the limitations stated in this audit report.
This audit has found that the site is suitable for undifferentiated use within the limited range of beneficial uses including high density residential; general open space (passive – non-recreational); and/or commercial developments, as qualified by the conditions presented in the following Section 15.2.
15.2 STATEMENT OF ENVIRONMENTAL AUDIT
After considering the issues described in this audit report, and in accordance with guidelines issued by the EPA under Section 53X of the Environment Protection Act 1970, the Environmental Auditor has decided not to issue a Certificate of Environmental Audit due to the residual contamination located in the natural, re-used and imported soils remaining on the site.
The Environmental Auditor makes the Statement as included at the front of his report. The Statement of Environmental Audit confirms that the environmental condition of the site is however considered to be suitable for high density residential, general open space (passive – non-recreational) and/or commercial use under the conditions described below (and as summarised in the Statement).
• All owners of the site, all occupiers and those made responsible for management of all parts of the site, including future dub-divisions, should be provided with a copy of this Statement of Audit, and also be provided with access to the Site Environmental Management Plan the preparation of which is also a condition of this Statement.
• An appropriate Soil and Groundwater Management Plan is required to be prepared for Area A of the West Melbourne Gasworks site and part of the site EMP.
• Engineered structures including the buildings, yards and open areas around buildings, pavement & parking areas, should be designed so that they are substantially covered with concrete, sealed surfaces or landscaping, that does not permit casual access to the underlying potentially contaminated soils.
• Residential or commercial occupation of basement areas is not permitted other than for normal reasonable access by building manager or maintenance staff, or for parking of cars or similar by others.
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• Protection of basement workers also requires a physical barrier to be maintained between the basement and surrounding soils. The nature of the barrier can include normal concrete retaining walls and a drainage layer. Basement ventilation should be provided consistent with that normally included for removal of exhaust fumes from a basement car park.
• A marker layer installed at generally 2 metres depth below the surface to indicate the location of remaining “D3”class soils, should be retained in place and, if accidentally disturbed, be appropriately replaced.
• Piles and deeper foundations and basement works should be constructed of concrete resistant to potential acid sulphate attack.
• Vegetable and fruit gardens are recommended not to be established in properties on the site unless a thickness of 500mm (or more if appropriate) of clean soil is provided as a growing medium for deeper rooted plants in areas where re-used D1 class soils remain accessible.
The S&GWMP must include the following provisions:
• All intrusive works on the site that may give rise to contact with contaminated soils and/or groundwater, are to be appropriately managed in accordance with the guidelines included in the SGWMP
• Maintain physical barriers such as fences to limit access to areas being excavated or developed to authorised personnel trained to a level appropriate for the soils to be excavated and/or exposed.
• It is recommended that no groundwater be abstracted from the site, except for dewatering of excavations, groundwater quality management and environmental remediation purposes.
• If it is proposed that groundwater be extracted on the site for any purpose, this proposal should be approved by an EPA accredited Environmental Auditor.
• Where groundwater remains contaminated within the site and is proposed to be penetrated by a basement, an effective seal to the basement (tanking) should be provided, unless a risk assessment indicates this is not required for the proposed use, or unless groundwater is remediated.
• Low permeability bund walls have been constructed at certain locations on the perimeter of the former Gasworks site to minimise the risk of recontamination from adjacent unremediated areas off-site. Monitoring of groundwater inside and outside the bund walls should be undertaken to monitor effectiveness.
• The low permeability bunds must be left in place and if damaged in any way, be replaced as constructed, until such time as the remainder of the Victoria Harbour Precinct outside of Area A is remediated.
• Ongoing monitoring of groundwater in the remaining portions of the former gasworks site and Victoria Harbour outside of the remediated area is a minimum requirement.
Management Plan Required for Remediated areas of Gasworks Site
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In addition to the Groundwater Mangement requirements, the Site S&GWMP for Area A will also be expected to include the following components:
• Constraints on excavation of service trenches and other sub-surface works during the life of the development unless service easement routes with clean soil are provided.
• Inclusion of a plan of the site identifying the remaining known and potential areas of contaminated or odorous soils.
• Inclusion of a plan of the site identifying available corridors of soils without significant contamination or odour, where future excavation for services, utilities etc may be undertaken with minimal restrictions.
• All management of future excavated soils will need to be undertaken in accordance with EPA regulations and guidelines concerning management of potentially contaminated soils applicable at the relevant time.
• Health and safety considerations are required to be included with all management plans relevant to all stages of construction work and continuing site and or groundwater management.
• An Odour Management Plan is to be included with the Site EMP and the continuing S&GWMP post completion of construction.
• Odour and dust control measures are to be implemented during all and subsequent construction phases.
Additional Comments and Recommendations:
• Isolated pockets of odorous soils may remain at depth on the site including in the re-used soils. If these are subsequently re-exposed, management requirements should include provision for construction of an odour blanket over the top of the odorous soils before backfilling occurs, or, if beneath buildings, installation of a passive venting system to remove odorous vapour that may be released over time from the soils around or beneath buildings.
• The topsoil thickness at completion of development was assumed to be 150mm in parkland and residential areas subsequently to be constructed on Area A in the volatilisation modelling performed by Egis (formerly CMPS&F) to provide the site specific soil clean up criteria. The change in minimum depth of D1 or better material overlying D3 soil, has made this assumption redundant with regard to potential health risks. However, this thickness may also be insufficient for deeper rooting flora, and specific considerations will need to be made for preparing the site for planting of deep rooting trees and other vegetation.
In addition to the conditions and limitations indicated above, the following will be required where a cut-off wall has been constructed in the area under development.
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• Where bund walls are constructed to provide localised protection of part of the site to limit potential for recontamination from off-site sources where soil and/or groundwater clean up have not been undertaken, these walls are to remain undisturbed until the adjacent soils have been remediated.
• Where any bund wall is disturbed to allow construction of roads or services, or any part of a building, it must be replaced in the same condition as it was found unless the adjacent area of contamination has been previously removed.
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16. USE OF AUDITOR’S SUPPORT TEAM
As required by the May 2001 Auditor Guidelines, it is noted that the Auditor’s support team has been employed throughout the Audit since the start of work in 1998. Tasks undertaken by the support team include:
• Review remediation action plans and risk assessments – The Auditor, Dr Raghava Dasika, Dr Janet Kester and for the later risk assessments, Dr Martin Howell
• Preparation of Auditor’s health and ecological risk assessments – Dr Martin Howell, Mr Jeff Rabbidge and Dr Jacinta Gorman
• Review of modelling by Enterra, and preparation of groundwater modelling for the site – Uwe Dannwolf and Damien Finlayson
• Review of groundwater issues and groundwater chemistry – Alan Deeney, Dr Bruno Coniglio, Damien Finalyson.
• Monitor site conditions during remediation, review of site history and audit tasks including review of Enterra validation report and QA, and the preparation of this report - The Auditor, Mr Raghava Dasika, Dr Jacinta Gorman, Mr Cameron Hardie.
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17. LIMITATIONS
This audit document and accompanying report have been prepared in accordance with Section 53X of the Environment Protection Act 1970. The audit has been undertaken to satisfy the requirements of the Docklands Authority, which is the relevant planning authority with jurisdiction over the site and the Clean Up Notice issued by the EPA, dated 15 August 1994, Ref no.0028.
It is acknowledged that the audit document and report may be used by the client, by the Environment Protection Authority and by the Docklands Authority planning department in reaching their conclusions about the site. The scope of work performed in connection with the audit review may not be appropriate to satisfy the needs of any other person. Any other person’s use of, or reliance on, the audit document and report, or the findings, conclusions, recommendations or any other material presented to them, is at that person’s sole risk.
In forming an opinion, the Auditor has relied on information supplied by Enterra Joint Venture. The Auditor has taken this information to represent a fair and reasonable characterisation of the site, within the limitations of the investigation as stated herein. No investigation, in practice, can be thorough enough to preclude the presence of materials on the subject property that presently, or in the future, may be considered hazardous. The actual characteristics of subsurface and surface materials may vary significantly between adjacent test points and sample intervals and at locations other than where direct observation, measurement or exploration have been made. Because regulatory evaluation criteria are constantly changing, concentrations of contaminants present and considered to be acceptable may, in the future, become subject to different regulatory standards and require remediation.
Opinions and judgements expressed herein, which are based on our understanding and interpretation of current regulatory standards, should not be construed as legal opinions.
In the event that changes in conditions on or near the site either exist or occur after the date of signing of a Certificate or Statement of Environmental Audit, the Auditor disclaims responsibility for the occurrence or ownership or effects of such conditions or materials, whether they be hazardous or otherwise.
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18. REFERENCES
The following publications have been directly or indirectly considered in the preparation of this Audit Report:
“Management of Manufactured Gas Plant Sites: The Gas Research Institute’s two volume practical reference guide” Thomas D. Hayes et al. 1996, Amherst Scientific Publishers, Massachusetts.
“Circle of Influence – A History of the Gas Industry in Victoria” Ray Proudley 1987, Hargreen Publishing Company in Association with the Gas and Fuel Corporation of Victoria.
“The Australian Gas Association Site Remediation Task Force – Draft Guidelines for the Assessment and Management of Gasworks Sites” prepared by CMPS&F (Egis) reference SE102.002.005.RevC, February 1997.
Assink, KW, van den Brink, WJ (1986). “Contaminated Soil” Proc. First International TNO Conf. on Contaminated Soil, 11-15 Nov., p399-405, The Netherlands Martinus Nijhoff Publishers.
ANZECC/NHMRC “Assessment and Management of Contaminated Sites”, January 1992;
ANZECC (1992). “Australian Water Quality Guidelines for Fresh and Marine Waters.”, November.
EPA Publication No. 759, “Environmental Auditor (Contaminated Land) - Guidelines for Issue of Certificates and Statements of Environmental Audit”, May 2001;
EPA Information Bulletin “Potential Contaminating Land Uses” (Publication No. 472);
EPA Information Bulletin “Classification of Wastes” (Publication No. 448), September 1995;
EPA State Environment Protection Policy (SEPP), “Groundwaters of Victoria”, 1997;
EPA Information Bulletin “Management of Waste Contaminated Soil and Low Level Contaminated Soil” (Publication No. 626), October 1998;
EPA Draft State Environmental Protection Policy “Prevention and Management of Contamination of Land” and Draft Policy Impact Assessment (Publication No. 622), September 1998;
ANZECC “Guidelines for the Laboratory Analysis of Contaminated Soils”, August 1996;
Australian Standard, AS4482.1, “Guide to the Sampling and Investigation of Potentially Contaminated Soil, Part 1 - Non-volatile and Semivolatile Compounds” September 1997;
Australian Standard, AS4482.2, “Guide to the Sampling and Investigation of Potentially Contaminated Soil, Part 2: Volatile Substances” September 1999.
“The Health Risk Assessment and Management of Contaminated Sites”, O. El Saadi, A. Langley, SA Health Commission, 1991;
“Protocol for the Health Risk Assessment and Management of Contaminated Sites”, Eds. A. Langley, M. Van Alpen, Contaminated Sites Monograph Series No. 2, 1993;
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“Identification an Assessment of Contaminated Land, Improving Site History Appraisal”, J.W. Edwards, M. Van Alpen, A. Langley, Contaminated Sites Monograph Series No. 3, 1994
National Environmental Protection Council: National Environment Measure (Assessment of Site Contamination) Dec 1999;
Netherlands Ministry of Housing, Spatial planning and the Environment (1994). “Environmental Quality Objectives in the Netherlands - a review of environmental quality objectives and their policy framework in the Netherlands.” Risk assessment and Environmental Quality Division, Directorate for Chemicals, External Safety and Radiation Protection.
Other reports referenced by the Auditor that are considered to be relevant to conclusions as to the environmental condition of the Site, are included in the list of Supporting Documents in the table of contents located at the front of this report.
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129 of 145 TABLE 13.5 WEST MELBOURNE GASWORKS SITE REMEDIATION WORKS MSG AQUIFER GROUNDWATER RESULTS SUMMARY ANZECC ANZECC 1992 & ARMCANZ NEPM 1999 UNREMEDIATED AREAS OFF GASWORKS SITE IN VICTORIA HARBOUR REMEDIATED AREAS NEPM 1999 NHMRC 2001 (2000) & 1992 Schedule B1 PRECINCT ON-SITE Schedule B1 Raw Waters
Drinking Water Laboratory Primary Contact ANALYTE Irrigation Water Stock Watering Health/ Limits of MW350C MW353C MW422C MW4C MW5C MW11C MW19C MW21C Recreation Aesthetics Reporting
Notes: (f) DDT indiv (g) ref drinking (n) Aesthetics Depth 27.5 24 29.5 25.3 29 26.4 ? ? (tot)=total water guidel's (d) corrosion Status OK OK OK OK OK OK OK OK (e) ANZECC 92 AREA Off Site Off Site Off Site Off Site Off Site Off Site A B (f) DDT indiv Date 15-Jan-02 15-Jan-02 11-Jan-02 11-Jan-02 22-Jun-01 11-Jan-02 28-Jun-01 17-Aug-01 Antimony 0.003 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Arsenic 0.05 0.1 0.5 0.007 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Beryllium 0.1 0.1 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.008 Cadmium 0.005 0.01 0.01 0.002 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Chromium 0.05 1 (tot) 1 (VI) 0.05 (tot) ??? 0.014 0.012 0.013 0.027 0.049 0.01 0.058 0.035 Cobalt 0.05 1 0.005 0.01 0.025 <0.005 0.048 <0.005 0.007 <0.005 0.021 Copper 1 0.2 0.5 2 / (1) 0.005 0.008 0.011 0.011 0.035 <0.005 0.006 0.011 0.016 Lead 0.05 0.2 0.1 0.01 0.005 <0.005 0.006 0.031 0.2 <0.005 <0.005 <0.005 0.027 Manganese 0.1 2 0.5/(0.1) 0.005 1.3 2.8 1.2 2.9 0.95 4.7 0.52 8.1 Mercury (inorg) 0.001 0.002 0.002 0.001 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 Molybdenum 0.01 0.01 0.05 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Nickel 0.1 0.02 1 0.02 0.005 0.013 0.018 0.006 0.055 <0.005 <0.005 <0.005 0.035 Selenium (total) 0.01 0.02 0.02 0.01 0.005 0.063 0.076 0.059 0.061 0.05 0.062 0.051 0.093 Tin 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Zinc 5 2 20 3 0.005 0.019 0.025 0.065 0.61 0.053 <0.005 0.054 0.11 Cyanide 0.1 (g) 0.08 0.005 <0.005 <0.005 0.01 0.04 <0.005 0.01 0.1 0.03 Ammonia as N 0.01 (g) 0.5 / (1.5) 1 52 36 34 27 32 28 81 24 TDS 1000 <3,500 (g) 500 (d) 2 19000 22000 17000 18000 23000 20000 16000 19000 pH 6.5-8.5 (g) 6.5-8.5 7 7 7.2 6.8 6.7 6.8 6.7 6.6 Benzene 0.01 (g) 0.001 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 Toluene (g) 0.8/(0.025) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 Ethylbenzene (g) 0.3/(0.003) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 Xylene (g) 0.6/(0.02) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 TPH C6-C9 (g) 1 <1 <1 <1 <1 <1 <1 <1 <1 TPH C10-C36 (g) 0.04 to 0.1 <0.3 <0.3 <0.3 0.3 <0.3 0.3 <0.3 <0.3 Total PAH (g) 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 BaP 0.00001 (g) 0.00001(e) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 OC Pesticides 0.003 (c) (g) 0.02 (f) 0.001 (indiv) <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 Phenols 0.002 (tot) (g) 0.002 (e) 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 Cresols (g) 0.001 ----<0.001 - <0.001 <0.001 Sulphate as Sulphur 400 45 100 63 180 180 160 12 190 VHCs (g) 0.005 to 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 SVHCs (g) 0.005 to 0.02 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Results in mg/L (h) ANZECC 1992 - total ammonium ions @ 15degC and ph 6.5 to 7.5 (95%)* protective of 95% of species IIWL = Indicative Interim Working Levels - based on data in Section 8 of Guidelines
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ANZECC NEPM 1999 SEPP Yarra UNREMEDIATED AREAS OFF GASWORKS SITE IN VICTORIA HARBOUR REMEDIATED AREAS ARMCANZ Schedule Waters PRECINCT ON-SITE (2000) B1
Marine Aquatic Laboratory ANALYTE Schedule F7 Ecosystems Ecosytems Limits of MW350C MW353C MW422C MW4C MW5C MW11C MW19C MW21C (95%)* Marine Reporting
Notes: (a) = IIWL (b) Freshwater Depth 27.5 24 29.5 25.3 29 26.4 ? ? (III) Cr III ecosystems Status OK OK OK OK OK OK OK OK (f) DDT indiv AREA Off Site Off Site Off Site Off Site Off Site Off Site A B Date 15-Jan-02 15-Jan-02 11-Jan-02 11-Jan-02 22-Jun-01 11-Jan-02 28-Jun-01 17-Aug-01 Antimony 0.27 (a) 0.03 (b) 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Arsenic 0.05 0.05 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Beryllium 0.004 0.004 (b) 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.008 Cadmium 0.0002 0.0055 0.002 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Chromium 0.01 0.0274 (III) 0.05 (tot) 0.005 0.014 0.012 0.013 0.027 0.049 0.01 0.058 0.035 Cobalt 0.001 0.005 0.01 0.025 <0.005 0.048 <0.005 0.007 <0.005 0.021 Copper 0.002 0.0013 0.005 0.005 0.008 0.011 0.011 0.035 <0.005 0.006 0.011 0.016 Lead 0.001 0.0044 0.005 0.005 <0.005 0.006 0.031 0.2 <0.005 <0.005 <0.005 0.027 Manganese 0.08 (a) 0.005 1.3 2.8 1.2 2.9 0.95 4.7 0.52 8.1 Mercury (inorg) 0.00005 0.0004 0.0001 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 Molybdenum 0.034 (a) 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Nickel 0.015 0.07 0.015 0.005 0.013 0.018 0.006 0.055 <0.005 <0.005 <0.005 0.035 Selenium (total) 0.005 0.003 (a) 0.07 0.005 0.063 0.076 0.059 0.061 0.05 0.062 0.051 0.093 Tin 0.01 (a) 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Zinc 0.005 0.015 0.05 0.005 0.019 0.025 0.065 0.61 0.053 <0.005 0.054 0.11 Cyanide 0.005 0.004 0.005 0.005 <0.005 <0.005 0.01 0.04 <0.005 0.01 0.1 0.03 Ammonia as N 1 52 36 34 27 32 28 81 24 TDS 2 19000 22000 17000 18000 23000 20000 16000 19000 pH 6.5 - 8.5 7 7 7.2 6.8 6.7 6.8 6.7 6.6 Benzene 0.001 0.7 0.3 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 Toluene 0.001 0.18 (a) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 Ethylbenzene 0.001 0.08 (a) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 Xylene 0.001 0.35 (a) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 TPH C6-C9 0.005 (a) 1 <1 <1 <1 <1 <1 <1 <1 <1 TPH C10-C36 0.007 (a) 0.04 to 0.1 <0.3 <0.3 <0.3 0.3 <0.3 0.3 <0.3 <0.3 Total PAH 0.003 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 BaP 0.0002 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 OC Pesticides 0.0004 (f) 0.001 (indiv) <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 Phenols 0.4 0.05 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 Cresols 0.001 ----<0.001 - <0.001 <0.001 Sulphate as Sulphur 45 100 63 180 180 160 12 190 VHCs 0.005 to 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 SVHCs 0.005 to 0.02 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Results in mg/L (h) ANZECC 1992 - total ammonium ions @ 15degC and ph 6.5 to 7.5, equiv to 0.02 unionid ammonia as in SEPP (95%)* protective of 95% of species IIWL = Indicative Interim Working Levels - based on data in Section 8 of Guidelines
Ref: S:\Projects\37858\005\Audit RepA\Table 13.5 GWJan2002 MSG Rev3.xls Ecosystem Criteria Page 1 of 1 DAMES & MOORE131 of 145 TABLE 13.5 WEST MELBOURNE GASWORKS SITE REMEDIATION WORKS CIS/FBS AQUIFER GROUNDWATER RESULTS SUMMARY ANZECC 92 Raw Waters & ANZECC 1992 & NEPM 1999 ANZECC NEPM 1999 NHMRC 2001 UNREMEDIATED AREAS OUTSIDE GASWORKS SITE REMEDIATED AREAS ON GASWORKS SITE Schedule B1 ARMCANZ Schedule B1 (2000)
Drinking Water Laboratory Primary Contact ANALYTE Irrigation Water Stock Watering Health/ Limits of MW350B MW353B MW415B MW417B MW422B BH44 MW17B MW19B MW21B MW22B Recreation Aesthetics Reporting
Notes: (f) DDT indiv (g) ref drinking (n) Aesthetics Depth 4 4.9 5.44 9.9 6.43 9.5 6.6 ? ? ? (tot)=total water guidel's (d) corrosion Status OK OK OK OK OK OK OK OK OK OK (e) ANZECC 92 AREA Off Site Off Site Off Site Off Site Off Site B BABB (f) DDT indiv Date 10-Jan-02 10-Jan-02 10-Jan-02 10-Jan-02 10-Jan-02 6-Jun-01 27-Jun-01 27-Jun-01 27-Jun-01 26-Jun-01 Antimony 0.003 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.005 <0.005 <0.005 <0.005 <0.005 Arsenic 0.05 0.1 0.5 0.007 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.01 0.012 0.01 <0.005 Beryllium 0.1 0.1 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Cadmium 0.005 0.01 0.01 0.002 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Chromium 0.05 1 (tot) 1 (VI) 0.05 (tot) 0.005 0.013 0.013 <0.005 0.013 0.021 0.028 0.045 0.071 0.04 0.053 Cobalt 0.05 1 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.005 0.01 0.026 Copper 1 0.2 0.5 2 / (1) 0.005 <0.005 <0.005 <0.005 <0.005 0.005 <0.005 0.008 0.015 0.007 0.025 Lead 0.05 0.2 0.1 0.01 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.008 <0.005 <0.005 <0.005 Manganese 0.1 2 0.5/(0.1) 0.005 1.1 1.1 1.8 0.39 0.097 0.25 0.2 0.37 0.98 1.2 Mercury (inorg) 0.001 0.002 0.002 0.001 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 Molybdenum 0.01 0.01 0.05 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.006 0.008 0.01 0.025 Nickel 0.1 0.02 1 0.02 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.061 Selenium (total) 0.01 0.02 0.02 0.01 0.005 0.024 0.024 0.02 0.09 0.047 0.067 0.03 0.054 0.024 0.061 Tin 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Zinc 5 2 20 3 0.005 0.025 0.025 0.014 0.018 0.015 0.007 0.015 0.026 0.021 0.041 Cyanide 0.1 (g) 0.08 0.005 0.07 0.07 0.06 0.01 0.02 0.4 0.3 0.09 0.4 0.7 Ammonia as N 0.01 (g) 0.5 / (1.5) 1 20 20 14 9 54 26 15 110 25 - TDS 1000 <3,500 (g) 500 (d) 2 5900 5900 6100 22000 23000 17000 19000 27000 14000 28000 pH 6.5-8.5 (g) 6.5-8.5 7.2 6.8 7.1 7.3 7.2 7.2 7.7 7.5 7.4 7.6 Benzene 0.01 (g) 0.001 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 0.16 <0.001 <0.001 0.76 <0.001 Toluene (g) 0.8/(0.025) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 0.006 <0.001 <0.001 0.009 <0.001 Ethylbenzene (g) 0.3/(0.003) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 0.016 <0.001 <0.001 0.042 <0.001 Xylene (g) 0.6/(0.02) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 0.02 <0.001 <0.001 0.032 <0.001 TPH C6-C9 (g) 1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 TPH C10-C36 (g) 0.04 to 0.1 1.1 1.1 0.5 0.8 1.4 2.3 <0.3 <0.4 <1.4 0.3 Total PAH (g) 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 0.26 <0.02 <0.02 0.13 <0.02 BaP 0.00001 (g) 0.00001(e) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 OC Pesticides 0.003 (c) (g) 0.02 (f) 0.001 (indiv) <0.01 <0.01 <0.01 <0.01 <0.01 <0.001 <0.01 <0.01 <0.01 <0.01 Phenols 0.002 (tot) (g) 0.002 (e) 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 0.05 <0.01 <0.01 0.012 <0.01 Cresols (g) 0.001 -----0.15 <0.001 <0.001 0.038 - Sulphate as Sulphur 400 24 210 22 43 4 57 320 18 91 74 VHCs (g) 0.005 to 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 SVHCs (g) 0.005 to 0.02 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Results in mg/L (h) ANZECC 1992 - total ammonium ions @ 15degC and ph 6.5 to 7.5 (95%)* protective of 95% of species IIWL = Indicative Interim Working Levels - based on data in Section 8 of Guidelines Exceedences of Stock Water and Irrigation Water figures have not been highlighted.
Ref: S:\Projects\37858\005\Audit RepA\Table 13.5 GWJan2002 FBSCIS Rev3.xls All Other Criteria Page 1 of 1 DAMES & MOORE132 of 145 TABLE 13.5 WEST MELBOURNE GASWORKS SITE REMEDIATION WORKS CIS/FBS AQUIFER GROUNDWATER RESULTS SUMMARY
ANZECC NEPM 1999 SEPP Yarra ARMCANZ Schedule UNREMEDIATED AREAS OUTSIDE GASWORKS SITE REMEDIATED AREAS ON GASWORKS SITE Waters (2000) B1
Marine Aquatic Laboratory ANALYTE Schedule F7 Ecosystems Ecosytems Limits of MW350B MW353B MW415B MW417B MW422B BH44 MW17B MW19B MW21B MW22B (95%)* Marine Reporting
Notes: (a) = IIWL (b) Freshwater Depth 4 4.9 5.44 9.9 6.43 9.5 6.6 ? ? ? (III) Cr III ecosystems Status OK OK OK OK OK OK OK OK OK OK (f) DDT indiv AREA Off Site Off Site Off Site Off Site Off Site B BABB Date 10-Jan-02 10-Jan-02 10-Jan-02 10-Jan-02 10-Jan-02 6-Jun-01 27-Jun-01 27-Jun-01 27-Jun-01 26-Jun-01 Antimony 0.27 (a) 0.03 (b) 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.005 <0.005 <0.005 <0.005 <0.005 Arsenic 0.05 0.05 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.01 0.012 0.01 <0.005 Beryllium 0.004 0.004 (b) 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Cadmium 0.0002 0.0055 0.002 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Chromium 0.01 0.0274 (III) 0.05 (tot) 0.005 0.013 0.013 <0.005 0.013 0.021 0.028 0.045 0.071 0.04 0.053 Cobalt 0.001 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.005 0.01 0.026 Copper 0.002 0.0013 0.005 0.005 <0.005 <0.005 <0.005 <0.005 0.005 <0.005 0.008 0.015 0.007 0.025 Lead 0.001 0.0044 0.005 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.008 <0.005 <0.005 <0.005 Manganese 0.08 (a) 0.005 1.1 1.1 1.8 0.39 0.097 0.25 0.2 0.37 0.98 1.2 Mercury (inorg) 0.00005 0.0004 0.0001 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 Molybdenum 0.034 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.006 0.008 0.01 0.025 Nickel 0.015 0.07 0.015 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 0.061 Selenium (total) 0.005 0.003 (a) 0.07 0.005 0.024 0.024 0.02 0.09 0.047 0.067 0.03 0.054 0.024 0.061 Tin 0.01 (a) 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Zinc 0.005 0.015 0.05 0.005 0.025 0.025 0.014 0.018 0.015 0.007 0.015 0.026 0.021 0.041 Cyanide 0.005 0.004 0.005 0.005 0.07 0.07 0.06 0.01 0.02 0.4 0.3 0.09 0.4 0.7 Ammonia as N 2.2 (h) 1 20 20 14 9 54 26 15 110 25 - TDS 2 5900 5900 6100 22000 23000 17000 19000 27000 14000 28000 pH 6.5 - 8.5 7.2 6.8 7.1 7.3 7.2 7.2 7.7 7.5 7.4 7.6 Benzene 0.001 0.7 0.3 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 0.16 <0.001 <0.001 0.76 <0.001 Toluene 0.001 0.18 (a) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 0.006 <0.001 <0.001 0.009 <0.001 Ethylbenzene 0.001 0.08 (a) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 0.016 <0.001 <0.001 0.042 <0.001 Xylene 0.001 0.35 (a) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 0.02 <0.001 <0.001 0.032 <0.001 TPH C6-C9 0.005 (a) 1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 TPH C10-C36 0.007 (a) 0.04 to 0.1 1.1 1.1 0.5 0.8 1.4 2.3 <0.3 <0.4 <1.4 0.3 Total PAH 0.003 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 0.26 <0.02 <0.02 0.13 <0.02 BaP 0.0002 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 OC Pesticides 0.0004 (f) 0.001 (indiv) <0.01 <0.01 <0.01 <0.01 <0.01 <0.001 <0.01 <0.01 <0.01 <0.01 Phenols 0.4 0.05 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 0.05 <0.01 <0.01 0.012 <0.01 Cresols 0.001 -----0.15 <0.001 <0.001 0.038 - Sulphate as Sulphur 24 210 22 43 4 57 320 18 91 74 VHCs 0.005 to 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 SVHCs 0.005 to 0.02 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 Results in mg/L (h) ANZECC 1992 - total ammonium ions @ 15degC and ph 6.5 to 7.5, equiv to 0.02 unionids ammonia as in SEPP (95%)* protective of 95% of species IIWL = Indicative Interim Working Levels - based on data in Section 8 of Guidelines
Ref: S:\Projects\37858\005\Audit RepA\Table 13.5 GWJan2002 FBSCIS Rev3.xls Ecosystem Criteria Page 1 of 1 DAMES & MOORE133 of 145 TABLE 13.5 WEST MELBOURNE GASWORKS SITE REMEDIATION WORKS FILL AQUIFER GROUNDWATER RESULTS SUMMARY ANZECC ARMCANZ ANZECC 1992 & (2000) & NEPM 1999 NEPM 1999 NHMRC 2001 UNREMEDIATED FILL AREAS REMEDIATED FILL AREAS ANZECC Schedule B1 Schedule B1 (1992) RAW WATERS
Drinking Water Laboratory Primary Contact ANALYTE Irrigation Water Stock Watering Health/ Limits of MW345A MW350A MW415A MW5A MW18A MW19A MW21A Recreation Aesthetics Reporting
Notes: (f) DDT indiv (g) ref drinking (n) Aesthetics Depth 2.53 2.55 1.7 3 ? 3.5 ? (tot)=total water guidel's (d) corrosion Status OK OK OK OK OK OK OK (e) ANZECC 92 AREA Off Site Off Site Off Site Off Site A A B (f) DDT indiv Date 10-Jan-02 10-Jan-02 10-Jan-02 22-Jun-01 26-Jun-01 Dry Jul 01 31-Jan-02 Antimony 0.003 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 - <0.005 Arsenic 0.05 0.1 0.5 0.007 0.005 <0.005 <0.005 <0.005 <0.005 0.009 - 0.03 Beryllium 0.1 0.1 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 - <0.005 Cadmium 0.005 0.01 0.01 0.002 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 - <0.005 Chromium 0.05 1 (tot) 1 (VI) 0.05 (tot) 0.005 <0.005 <0.005 0.006 0.27 0.005 - 0.008 Cobalt 0.05 1 0.005 <0.005 0.008 <0.005 <0.005 <0.005 - 0.021 Copper 1 0.2 0.5 2 / (1) 0.005 <0.005 <0.005 0.009 <0.005 <0.005 - <0.005 Lead 0.05 0.2 0.1 0.01 0.005 <0.005 <0.005 0.035 0.017 <0.005 - <0.005 Manganese 0.1 2 0.5/(0.1) 0.005 4.5 5.5 1.5 5.9 0.006 - 0.05 Mercury (inorg) 0.001 0.002 0.002 0.001 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 - <0.001 Molybdenum 0.01 0.01 0.05 0.005 <0.005 <0.005 <0.005 <0.005 0.005 - 0.02 Nickel 0.1 0.02 1 0.02 0.005 0.008 0.008 0.007 <0.005 0.013 - 0.17 Selenium (total) 0.01 0.02 0.02 0.01 0.005 0.017 0.007 0.018 0.023 0.007 - 0.044 Tin 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 - <0.005 Zinc 5 2 20 3 0.005 0.026 0.031 0.09 0.04 <0.005 - 0.033 Cyanide 0.1 (g) 0.08 0.005 0.01 0.2 0.1 0.03 0.6 - 2.6 Ammonia as N 0.01 (g) 0.5 / (1.5) 1 58915 24 - 100 TDS 1000 <3,500 (g) 500 (d) 2 4700 2200 3900 13000 1200 - 5000 pH 6.5-8.5 (g) 6.5-8.5 7 6.8 7.1 6.8 10.9 10.6* Benzene 0.01 (g) 0.001 0.001 0.003 <0.001 <0.001 <0.001 <0.001 - 68 Toluene (g) 0.8/(0.025) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 - 0.04 Ethylbenzene (g) 0.3/(0.003) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 - 0.012 Xylene (g) 0.6/(0.02) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 - 0.075 TPH C6-C9 (g) 1 <1 <1 <1 <1 <1 - <1 TPH C10-C36 (g) 0.04 to 0.1 1.3 1 0.4 <0.3 2 - 23 Total PAH (g) 0.02 0.02 <0.02 <0.02 <0.02 0.38 - 1.2 BaP 0.00001 (g) 0.00001(e) 0.001 <0.001 <0.002 <0.001 <0.001 <0.001 - <0.01 OC Pesticides 0.003 (c) (g) 0.02 (f) 0.001 (indiv) <0.01 <0.01 <0.01 <0.01 <0.01 - <0.01 Phenols 0.002 (tot) (g) 0.002 (e) 0.01 <0.01 <0.01 <0.01 <0.01 0.023 - <0.01 Cresols (g) 0.001 --<0.001 - - - Sulphate as Sulphur 400 62 50 32 830 21 - 61* VHCs (g) 0.005 to 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 - <0.02 SVHCs (g) 0.005 to 0.02 <0.005 <0.005 <0.005 <0.005 <0.005 - <0.005 Results in mg/L (h) ANZECC 1992 - total ammonium ions @ 15degC and ph 6.5 to 7.5 * June 2001 Result (95%)* protective of 95% of species IIWL = Indicative Interim Working Levels - based on data in Section 8 of ANZECC 2000 Guidelines
Ref: S:\Projects\37858\005\Audit RepA\Table 13.5 GWJan2002 Fill Rev3.xls All Other Criteria Page 1 of 1 DAMES & MOORE134 of 145 TABLE 13.4b WEST MELBOURNE GASWORKS SITE REMEDIATION WORKS REUSED D3 MATERIAL SUMMARY Reused Fill - Fine Stockpile Reused Fill - Treated Stockpiles Reused Fill - Pugmill Stockpiles 95% UCL 95% UCL 95% UCL Maximum Point Maximum Point Maximum Point Normal Normal Normal Concentration Concentration Concentration NEPM D NEPM E NEPM EIL D1 (mg/kg) D3 (mg/kg) (mg/kg) (mg/kg) (mg/kg) Antimony - - Arsenic 400 200 20 300 300 38 10 6 11 59 11 Beryllium 80 40 ------Cadmium 80 40 3 50 50 4 1 0.5 1 0.5 1 Chromium 400 200 1 2,750 2,750 59 20 42 25 33 18 Copper 4,000 2,000 100 1,000 1,000 190 30 49 28 81 22 Cobalt 400 200 - 100 500 31 11 26 14 13 8 Lead 1,200 600 600 1,200 3,000 2000 131 210 103 480 108 Mercury 60 30 1 20 20 6 1 4.2 1 7.2 1 Molybdenum - - - 400 400 6 3 2.5 3 7.1 3 Nickel 2,400 600 60 1,000 1,000 77 40 70 47 58 30 Selenium - - - 100 100 5 2 1.5 2 5.9 2 Tin - - - 500 500 68 - 2.5 1 65 8 Zinc 28,000 14,000 200 5,000 5,000 480 96 140 101 300 83 Benzene - - - 6 6 1 - 0.05 0.05 0.1 0.1 Toluene - - - 20 20 2.5 - 0.2 0.07 0.1 0.1 Ethyl-Benzene - - - 10 10 1.7 - 0.05 0.05 0.1 0.1 Xylenes - - - 70 70 12 - 6.7 1.1 0.1 0.1 TPH C6 to C9 - - - 400 1000 190 - 10 10 140 13.5 TPH C10 to C36 - 4,000 10,000 15000 2001.1 2600 1726.2 11000 2041.5 Naphthalene - - - - - 97 12.0 34 15.5 36 12.3 Total PAHs 80 40 - 140 500 1600 282.6 440 328.3 420 264.4 Benzo(a)pyrene 4 2 - 7 25 78 18.2 25 20.9 25 20.4 Sulphate as Sulphur - - 600 2,000 2,000 3800 1622.5 1800 713 970 181 Ammonia as Nitrogen - - 500 500 170 - 210 - 46 16 Cyanide (total) 1,000 500 - 1,000 2,500 1200 - 325 177 250 134 Fluoride - - - 4,500 4,500 17 2.3 5 2 17 4 Phenol 34,000 17,000 - 17,000 17,000 2.2 0.4 0.6 0.2 1 0.3 Cresols (total) - - - 10 25 20 - 1.2 0.9 4.5 - VHCs (max result) - - - 5 5 0.1 - 0.025 0.025 0.01 0.01 SVHCs (max result) - - - 5 5 0.003 0.003 0.003 0.003 0.003 0.003 OC Pesticides total - - - 5 10 13 7.6 11 9.6 12 5.35
S:\Projects\37858\005\Audit rep A\Table 13b.xls 135 of 145 TABLE 13.4a WEST MELBOURNE GASWORKS SITE REMEDIATION WORKS AREA A BASE SAMPLE RESULTS SUMMARY - AREA A DOMAIN A1 DOMAIN A2 DOMAIN A3 North DOMAIN A3 South Maximum Point 95% UCL Maximum Point 95% UCL Maximum Point 95% UCL Maximum Point 95% UCL Concentration Log Normal Concentration Log Normal Concentration Log Normal Concentration Log Normal NEPM D NEPM E NEPM EIL D1 (mg/kg) D3 (mg/kg) (mg/kg) (mg/kg) (mg/kg) Antimony - - Arsenic 400 200 20 300 300 20 1.9 16 1.9 17 2.2 94 11.8 Beryllium 80 40 ------Cadmium 80 40 3 50 50 1 - 1 - 1 - 1 - Chromium 400 200 1 2,750 2,750 43 3.2 40 3.2 32 3.1 57 3.2 Copper 4,000 2,000 100 1,000 1,000 39 2.5 25 2.3 63 2.8 190 44.5 Cobalt 400 200 - 100 500 32 2.2 37 2.2 13 1.6 29 2.4 Lead 1,200 600 600 1,200 3,000 160 13.3 27 10.0 220 39.7 1000 153.0 Mercury 60 30 1 20 20 2 0.1 3 0.2 7 0.4 3 0.5 Molybdenum - - - 400 400 7 1.1 9 1.1 9 1.1 7 1.1 Nickel 2,400 600 60 1,000 1,000 130 3.2 110 3.0 74 3.0 210 51.5 Selenium - - - 100 100 3 0.7 4 0.7 4 0.7 2 0.7 Tin - - - 500 500 5 - 9 - 18 3.1 13 2.7 Zinc 28,000 14,000 200 5,000 5,000 220 3.1 120 3.7 960 88.5 700 119.0 Benzene - - - 6 6 11 0.3 8.2 2.4 1.3 0.1 0.2 - Toluene - - - 20 20 4.2 0.1 16 1.0 0.3 - 0.05 - Ethyl-Benzene - - - 10 10 1.6 0.1 2.4 0.1 1.6 0.2 1 0.1 Xylenes - - - 70 70 7.4 0.3 8.4 0.5 5.1 0.2 3.8 0.2 TPH C6 to C9 - - - 400 1000 80 - 52 - 10 - 34 - TPH C10 to C36 - 4,000 10,000 910 129.7 1,300 159.7 1,600 298 840 169 Naphthalene - - - - - 78 14.4 62 101.7 48 17 15 3.0 Total PAHs 80 40 - 140 500 200 14.3 200 25.0 400 85 100 30.6 Benzo(a)pyrene 4 2 - 7 25 5.2 0.3 12 0.2 23 4 12 3.8 Sulphate as Sulphur - - 600 2,000 2,000 2500 298.0 1900 373.0 520 - 3400 504(a) Ammonia as Nitrogen - - 500 500 670 5.5 1100 363.0 920 5.8 430 5.5 Cyanide (total) 1,000 500 - 1,000 2,500 16 2.0 12 3.0 280 13.2 23 6.0 Fluoride - - - 4,500 4,500 18 1.9 10 5.0 29 2.1 25 2.1 Phenols (sum) 34,000 17,000 - 17,000 17,000 ------Cresols (total) - - - 10 25 ------VHCs (max result) - - - 5 5 0.3 0.005 0.4 0.04 0.3 0.3 0.3 0.2 SVHCs (max result) - - - 5 5 0.3 0.005 0.1 0.01 0.05 0.0 0.05 0.02 OC Pesticides total - - - 5 10 < LOR < LOR < LOR < LOR < LOR < LOR < LOR < LOR (a) Not reported by Enterra. Value outside of normal statistical limits
S:\Projects\37858\005\Audit rep A\Table 13a.xls 136 of 145 TABLE 13.5 WEST MELBOURNE GASWORKS SITE REMEDIATION WORKS FILL AQUIFER GROUNDWATER RESULTS SUMMARY ANZECC SEPP Yarra NEPM 1999 ARMCANZ UNREMEDIATED FILL AREAS REMEDIATED FILL AREAS Waters Schedule B1 (2000)
Marine Aquatic Laboratory ANALYTE Schedule F7 Ecosystems Ecosytems Limits of MW345A MW350A MW415A MW5A MW18A MW19A MW21A (95%)* Marine Reporting
Notes: (a) = IIWL (b) Freshwater Depth 2.53 2.55 1.7 3 ? 3.5 ? (III) Cr III ecosystems Status OK OK OK OK OK OK OK (f) DDT indiv AREA Off Site Off Site Off Site Off Site A A B Date 10-Jan-02 10-Jan-02 10-Jan-02 22-Jun-01 26-Jun-01 Dry Jul 01 31-Jan-02 Antimony 0.27 (a) 0.03 (b) 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 - <0.005 Arsenic 0.05 0.05 0.005 <0.005 <0.005 <0.005 <0.005 0.009 - 0.03 Beryllium 0.004 0.004 (b) 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 - <0.005 Cadmium 0.0002 0.0055 0.002 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 - <0.005 Chromium 0.01 0.0274 (III) 0.05 (tot) 0.005 <0.005 <0.005 0.006 0.27 0.005 - 0.008 Cobalt 0.001 0.005 <0.005 0.008 <0.005 <0.005 <0.005 - 0.021 Copper 0.002 0.0013 0.005 0.005 <0.005 <0.005 0.009 <0.005 <0.005 - <0.005 Lead 0.001 0.0044 0.005 0.005 <0.005 <0.005 0.035 0.017 <0.005 - <0.005 Manganese 0.08 (a) 0.005 4.5 5.5 1.5 5.9 0.006 - 0.05 Mercury (inorg) 0.00005 0.0004 0.0001 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 - <0.001 Molybdenum 0.034 (a) 0.005 <0.005 <0.005 <0.005 <0.005 0.005 - 0.02 Nickel 0.015 0.07 0.015 0.005 0.008 0.008 0.007 <0.005 0.013 - 0.17 Selenium (total) 0.005 0.003 (a) 0.07 0.005 0.017 0.007 0.018 0.023 0.007 - 0.044 Tin 0.01 (a) 0.005 <0.005 <0.005 <0.005 <0.005 <0.005 - <0.005 Zinc 0.005 0.015 0.05 0.005 0.026 0.031 0.09 0.04 <0.005 - 0.033 Cyanide 0.005 0.004 0.005 0.005 0.01 0.2 0.1 0.03 0.6 - 2.6 Total Ammonia as N 0.02 - 0.03mg/L 2.2 (h) 1 5 8 9 15 24 - 100 TDS 2 4700 2200 3900 13000 1200 - 5000 pH 6.5 - 8.5 7 6.8 7.1 6.8 10.9 10.6* Benzene 0.001 0.7 0.3 0.001 0.003 <0.001 <0.001 <0.001 <0.001 - 0.68 Toluene 0.001 0.18 (a) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 - 0.04 Ethylbenzene 0.001 0.08 (a) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 - 0.012 Xylene 0.001 0.35 (a) 0.001 <0.001 <0.001 <0.001 <0.001 <0.001 - 0.075 TPH C6-C9 0.005 (a) 1 <1 <1 <1 <1 <1 - <1 TPH C10-C36 0.007 (a) 0.04 to 0.1 1.3 1 0.4 <0.3 2 - 23 Total PAH 0.003 0.02 0.02 <0.02 <0.02 <0.02 0.38 - 1.2 BaP 0.0002 0.001 <0.001 <0.002 <0.001 <0.001 <0.001 - <0.001 OC Pesticides 0.0004 (f) 0.001 (indiv) <0.01 <0.01 <0.01 <0.01 <0.01 - <0.01 Phenols 0.4 0.05 0.01 <0.01 <0.01 <0.01 <0.01 0.023 - <0.01 Cresols 0.001 --<0.001 - - - Sulphate as Sulphur 62 50 32 830 21 - 61* VHCs 0.005 to 0.02 <0.02 <0.02 <0.02 <0.02 <0.02 - <0.02 SVHCs 0.005 to 0.02 <0.005 <0.005 <0.005 <0.005 <0.005 - <0.005 Results in mg/L (h) ANZECC 1992 - total ammonium ions @ 15degC and ph 6.5 to 7.5, equiv to 0.02 unionisammonia as in SEPP * June 2001 Result (95%)* protective of 95% of species IIWL = Indicative Interim Working Levels - based on data in Section 8 of ANZECC 2000 Guinesd
Ref: S:\Projects\37858\005\Audit RepA\Table 13.5 GWJan2002 Fill Rev3.xls Ecosystem Criteria Page 1 of 1 DAMES & MOORE137 of 145 WEST BOUNDARY Estimated recovery EAST BOUNDARY level of groundwater future Clay cut-off AREA A AREA B on boundary 0 FILL 2 Current level Former Final dept FILL gasholder 4 h of remed excavation iation CIS 6 ? ? 8 SANDY FBS ? CLAYEY COODE ISLAND ? ? 10 SILT (CIS) ? OLDER 12 ? CLAYEY ? VOLCANICS FISHERMENS CLAY ) 14 D ? BEND SILT ? H A
( (FBS)
16 ? s ? e r ? t e
M 18 ? WERRIBEE FORMATION ? 20 ? ? ?
22 ? MORAY STREET 24 GRAVELS (MSG) 26 ? ? 28 SILURIAN ? SILTSTONE 30 ? ?
400 metres (approx)
TITLE CLIENT: REVISION: DESIGNED: DOCKLANDS AUTHORITY A C.J.H. CONCEPTUAL SCALE: DRAWN: AS SHOWN L.L.B. GEOLOGICAL DRAWING No: CHECKED: MODEL OF WEST S/37858-005-gasworks MELBOURNE CAD FILE NO: APPROVED: GASWORKS SITE PROJECT: Figure 5 FIGURE REMEDIATION OF DATE: STATUS: WEST MELBOURNE GASWORKS FEBRUARY 2002 Draft 5 A4 138 of 145 139 of 145 K C O D
I A R T O I C F V TAR MW353 TANK O 104 O F4 RF5ELIEF TP49 HOLDER T T 103 E H&G 117 S E E3 PLANT R 116 F6 C C S T OIL R POW H MW350 TP46 ER GAS PLE4A STORAGE TP41 TP42 TD47 NT A A 101 B T OILETPR43 Y .0 T HOUSE ASH TP48 R 0 .0 O 115 E5A EF67 G C TP35 ONVEY L 0 128OR E5 G N D2 GAS I 4 I E R P L HOLDER 0. S CTPO30KE TP36 D TP44 0.4 BINS RETOTPR37T GAS O 113 N HOUSE BOILTP45 127 D3 ERS E6 TP31 A G HOLDER A T H R D L D4 126 TP39 137 E C1 TP38 DE6 0.6 A TP24 I TP32 M E 0.6 O C IFE PL 136 ANT GF R 119 TP25 D5 EENGINE C S C2 TP40 GA TORA 130 RO S T 118 GE S OM REGG RS MW345 BINS C ULATING AT D6 S TP18 TP33 ALYTIC STATIO MW202 TP26 TP27 O S N IL GAS P B D6A LANT C
213 C3 C B1 CIRC R REL A 196 TP34 R
IEF 2 O
H TP29 U
218 MW218 HO W
TP19 LDER TP28 N I
B D
TP20 T
D 212 A
C4 B
E S G Y
S TP21 I
TO N N R H ES 145 152
L
G S 138 BH59 I E RE N
TORT E B H P OUSES C5 G TAR PIT
B2 TP22 R L R
TP23 / S
TP14 A MW138 O
TP7 N 216 155 T TP15 A BH57 C6 B3 BH56 D C7 215 TP8 BH58 MW166 166 A1 TP9 TP16
E OF TP17 FICE C TP10 I 153 B4 TP1 F TP11 B5 N F MW409 O TP12 O GAS PURIFIERS R TP2 A2 GAS T 217 BH51 BH55 H TP13 DRYING LAB A3 B6 B7 MW422 W TP3 168 PLANT H A R B-HOLE TP4 A4 EF17F5LUENT F TP5 PLANT R TP6 A5 O BH53 A BH52 D A6 A7 MW415 BH54 A7A MW417 LEGEND: Y A R R MW202 Monitoring Well location A R Golder-December 1997 I V E R Egis-September 1998
CLIENT REVISION: DESIGNED: TITLE C.J.H. 0 50 100 150 200 A DOCKLANDS AUTHORITY SCALE: DRAWN: Adopted Groundwater Approximate Scale in Metres As shown L.L.B. Contours based on DRAWING No: CHECKED: 1997 and 1998 data S/37858-005-nov 2001
CAD FILE NO: APPROVED: PROJECT Figure 4b FIGURE REMEDIATION OF WEST- DATE: STATUS: MELBOURNE GASWORKS FEBRUARY 2002 Draft 4 140 of 145 K C O D
I A R T O MW5A MW363C I C MW5C MW363B F V TAR TANK O 104 O F4 RF5ELIEF TP49 HOLDER T T 103 MW17B E H&G 117 S E E3 PLANT R 116 F6 C C T OIL R S POW H MW19C TP46 ER GAS PLE4A STORAGE A TP41 TP42 TD47 NT A 101 B T MW350C OILETPR43 Y MW350T A MW19BHOUSE ASH TP48 R O 115 E5A EF67 G C TP35 ONVEY L MW19A 128OR E5 G N D2 GAS I I E R P MW350B L HOLDER S CTPO30KE TP36 D TP44 BINS RETOTPR37T GAS O 113 N HOUSE BOILTP45 127 D3 ERS E6 TP31 A G HOLDER A BH44 T H R D L D4 126 TP39 137 E C1 TP38 DE6 TP24 A I TPA232 M E O
C IFE PL 136 ANT GF R 119 TP25 D5 EENGINE C S C2 TP40 GA TORA 130 RO S T MW345A 118 GE S OM REGG RS A3 North BINS C ULATING AT D6 S TP18 TP33 ALYTIC STATIO TP26 TP27 O S N IL GAS P B D6A LANT C
213 C3 C B1 CIRC R REL A 196 TP34 R
IEF 2 O
H TP29 U
MW21818A HO W
TP19 LDER TP28 N I
B D
TP20 T
D 212 A
C4 B
E S G Y
S TP21 I
TO N N R H ES 145 152
L
G S 138 BH59 I E RE N
TORT E B H P OUSES C5 G TAR PIT
B2 TP22 R L R
TP23 / S
TP14 A O
TP7 N 216 155 T TP15 A BH57MW21B C6 B3 BH56 D C7 215 TP8 BH58 166 A1 TP9 TP16 MW21C E MW21A OF TP17 FICE C TP10 A3 SouthI 153 A1 B4 TP1 F TP11 B5 N F O TP12 O GAS PURIFIERS R TP2 A2 GAS T 217 BH51 BH55 H TP13 DRYING LAB A3 B6 B7 MW422B W TP3 168 PLANT H A MW422C R B-HOLE TP4 A4 EF17F5LUENT F TP5 PLANT R TP6 A5 O BH53 MW415A A BH52 D A6 A7 BH54 MW22B A7A LEGEND: MW415B MW4C MW4B MW417B MW19A Shallow (Fill) Monitoring Well Y A R R A MW19B Intermediate (CIS/FBS) Monitoring Well MW11C R MW19C Deep (MSG) Monitoring Well I V E R
CLIENT REVISION: DESIGNED: TITLE 0 50 100 150 200 A C.J.H. DOCKLANDS AUTHORITY Approximate Scale in Metres SCALE: DRAWN: BOREHOLE LOCATION As shown L.L.B. PLAN DRAWING No: CHECKED: S/37858-005-gasworks
CAD FILE NO: APPROVED: PROJECT Figure 3 FIGURE REMEDIATION OF WEST- DATE: STATUS: MELBOURNE GASWORKS FEBRUARY 2002 Draft 3 141 of 145 K O C D
I A R T O C V I
F TAR TANK O 104 O F4 RELIF5 EF TP49 HOLDER T T 103 E H&G 117 S E E3 PLANT R 116 F6 C C T OIL R S POW H TP46 ER GAS PLE4A STORAGE TP41 TP42 TD47 NT A A 101 B T OILETP43R Y T HOUSE ASH TP48 R O 115 E5A EF67 G C TP35 ONVEY L 128OR E5 G N D2 GAS I I E R P L HOLDER S CTP30OKE TP36 D TP44 BINS RETOTP37RT GAS O 113 N HOUSE BOILTP45 127 D3 ERS E6 TP31 A G HOLDER A T H R D L D4 126 TP39 137 E C1 TP38 DE6 TP24 A I TP32 M E O
C IFE PL 136 ANT GF R 119 TP25 D5 EENGINE C S C2 TP40 GA TORA 130 RO S T 118 GE S OM REG RS BINS C ULATING ATA D6 S TP18 TP26 TP33 LYTIC STATIO TP27 O S N IL GAS P B D6A
LANT C
213 C3 C B1 CIRCA R REL 1962 TP34 R
IEF O
TP29 H U
218 HOL W
TP19 DER TP28 N I B D
TP20 T
D 212 A
C4 B
E S TP21 G Y
S I
TO N
N R H ES 145 152
L
G S 138 BH59 I E RE N
TORT E B H P
OUSES C5 G TAR PIT TP22 R
B2 R L
TP23 / S TP14Area A A O
TP7 N
216 155 T TP15 A BH57 C6 B3 BH56 D C7 215 TP8 BH58 166 A1 TP9 TP16
E OF TP17 FICE C TP10 I 153 B4 F Area B TP1 TP11 B5 N F O TP12 O GAS PURIFIERS R TP2 A2 GAS T 217 BH51 BH55 H TP13 DRYING LAB A3 B6 B7 W TP3 168 PLANT H A R B-HOLE TP4 A4 EFFL175 UENT F TP5 PLANT R TP6 A5 O BH53 A BH52 D A6 A7 BH54 A7A
Y A R R A
R I V E R
CLIENT REVISION: DESIGNED: TITLE A C.J.H. 0 50 100 150 200 DOCKLANDS AUTHORITY SCALE: DRAWN: Site Plan Approximate Scale in Metres As shown L.L.B. DRAWING No: CHECKED: S/37858-005-gasworks CAD FILE NO: APPROVED: PROJECT Figure 2 FIGURE REMEDIATION OF WEST DATE: STATUS: MELBOURNE GASWORKS January 2002 Final 2 142 of 145 SITE LOCATION
CLIENT REVISION: DESIGNED: TITLE 0 500 A C.J.H. DOCKLANDS Approximate Scale in Metres SCALE: DRAWN: Locality Map of As shown L.L.B. Former West DRAWING No: CHECKED: Melbourne S/37858-005-gasworks CAD FILE NO: APPROVED: Gasworks Site PROJECT locality FIGURE REMEDIATION OF WEST DATE: STATUS: MELBOURNE GASWORKS February 2002 Final 1 143 of 145 Appendix A Site Plan Supplied by Docklands Authority Defining Boundaries of The Site (GHD)
Ref: CH\dm-mel-nt1\S:\Projects\37858\005\Audit rep A\GasworksAuditRepRev0.doc DAMES & MOORE
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