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Highlights
- Contamination audit of a former naval dockyard, situated
on an island in Sydney Harbour
- Extensive soil, groundwater and sediment sampling programs
- Liaison with regulatory authorities and preparation
of remediation plan.
Background
Cockatoo Island had operated for over 100 years as the
principal naval dockyard and naval shipbuilding establishment
in Australia. Previous uses had included a convict penal
settlement, women's prison, reformatory and seamanship training
centre. The Commonwealth Government, having decided to sell
the island, required an audit to assess the nature and extent
of soil and groundwater contamination on the island, and
to provide the data necessary to formulate and cost appropriate
remediation strategies.
Hydrogeological Environment
The central core of Cockatoo Island is composed of Triassic
sandstone (Hawkesbury Group). This core has been quarried
and tunnelled. Surrounding the core is an area of deep fill
which had been progressively emplaced on top of harbour
floor sediments throughout the industrial history of the
island. This fill comprises sandstone blocks, concrete,
rubble, steel plates and general waste materials. The groundwater
level is tidal, and generally 2 to 3 metres below surface
in the filled areas.
Contaminants
Potential contaminants included hydrocarbons, heavy
metals (including mercury and lead), marine paints and industrial
degreasing agents.
Objectives and Scope
Stage 1. In 1991 Coffey Partners International was
commissioned by the Australian Department of Defence to
carry out an initial pollution audit coincident with the
decommissioning of the Dockyard; Coffey appointed C. M.
Jewell as project manager. A historical uses survey carried
out by Defence was reviewed and supplemented by additional
material collected by Coffey. A detailed work plan was prepared,
and discussed with and approved by the NSW State Pollution
Control Commission (SPCC). An intensive period of sampling
and analysis followed, and results were compiled in a series
of factual and interpretive reports, culminating in the
development of a remedial strategy for the island. This
strategy has been approved by the SPCC. Additional work
commissioned from Coffey by Defence included a survey of
background concentrations of heavy metals in areas surrounding
Cockatoo Island, a forensic study to assess the age and
origin of some contaminants detected on the island, and
briefing of Queen's Counsel.
Stage 2. In 1993 the need for further more detailed
assessment to support a legal claim against the former operators
of the island became apparent. The Australian Government
Solicitor and the Department of Defence appointed CH2M HILL
Australia to carry out an investigation of structures, soils,
groundwater and sediment contamination. This work was to
lead into preparation of human health and ecological risk
assessments, and development of a final remediation strategy
and a defensible costing. CH2M HILL Australia subcontracted
management of the initial field program to C. M. Jewell
& Associates.
The intensive field program involved supplementary soil
sampling; forensic sampling from buildings, drains and tunnels;
drilling, sampling and testing a series of groundwater monitoring
boreholes; and a program of offshore sediment sampling using
a drop corer.
Results were compiled for incorporation in the risk assessment
and remediation costing programs.
Subsequently, C. M. Jewell & Associates has provided
ongoing support to CH2M HILL and Defence, including review
of the risk assessment report, input to the remedial strategies
and remediation costing report, management of a further
phase of drilling and groundwater sampling, tidal monitoring,
and assessment of changes in ground conditions during the
Coffey and CH2M HILL investigations.
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Projects
