Document ID: chunk:federal_register_of_legislation:F2018L00053:body:0:p31
Version: federal_register_of_legislation:F2018L00053
Segment Type: other
Provision Reference: 
Character Range: 78409–81318

significant risk to users of the site as long as the soils in these areas are stable and remain undisturbed. This has been achieved in the short term in the plateau area by laying down temporary clean surface cover in priority areas consisting of topsoil/ grass or gravel. Long-term requirements will need to be considered in the remediation of each area.
Results from assessments showed that soils in all areas of Cockatoo Island contained contamination exceeding one or more of the health-based criteria applicable for the land uses being considered by the Harbour Trust, and therefore remediation would be required.

Stormwater and Sewerage System
During Dockyard operations, contaminated wastes were either disposed of or washed into the stormwater and sewerage systems. These systems were in poor condition, with sludge and grit remaining in pits, lines and tanks. Assessment of wastes in these systems showed elevated levels of heavy metals and PAHs, however other contaminants may also have been present. This represented a potential source of ground contamination, which could have become mobile under high flow conditions and migrated into the surrounding aquatic environment.
During Dockyard operations, stormwater either flowed directly to the harbour, or via the remaining system of pits and pipes. Some ponding and ground infiltration may still occur, particularly in areas where buildings have been demolished and ground slabs remain. The island's sewerage system, which is no longer in use, was comprised of:
  * Sewerage treatment plant (Building 56), located on the western side of the island adjacent to the Power House and Pumping Station;
  * A sewerage transfer station (Building 149); and
  * At least 9 septic tanks located around the site.
The Harbour Trust initially installed a small temporary sewage treatment plant to meet the needs of visitors and the workforce engaged for rehabilitation of the island, however as use of the Island increased, this facility was replaced by a macerator, that treats effluents prior to connection with the Sydney Water system near Elkington Park, Balmain.
Surface and Groundwater
A number of surface water and groundwater investigations were undertaken on Cockatoo Island in the 1990s. In 2001, the Harbour Trust also carried out a program of water quality monitoring in harbour waters surrounding the island (PPK, 2001), which found:
  * Dissolved copper, zinc, mercury and organotin compounds are considered to be the main contaminants of concern in groundwater, as they have been recorded as elevated with respect to the Australian and New Zealand Guidelines for Fresh and Marine Water Quality, 2000 (ANZECC). Groundwater quality has been noted to vary significantly within fill material over short distances;
  * Surface water investigations carried out in 2001 identified that copper, zinc and tributyltin were the main contaminants of concern