Scheduled Chemical Waste
Arising from the extensive clean up program was a quantity of excavated soil contaminated with scheduled chemical waste.
Broadly, scheduled chemical wasted can be defined as hazardous material containing chemicals exceeding a concentration threshhold and is difficult to safely dispose of without special technologies and facilities.
The treatment of scheduled chemical waste at Sydney Olympic Park pioneered use of innovative environmental technology and successfully reduced contaminants with a concentration of up to 900,000 parts per million to a concentration of less than one part per million.
There are 24 compounds listed in the 1994 Scheduled Chemical Waste Chemical Control Order, under the Environmentally Hazardous Chemicals Act 1985. These include a range of chlorinated benzenes, chlorinated phenols and organochlorine compounds formerly commonly used as pesticides such as DDT, DDE, DDD, Dieldrin, Endrin, Heptachlor and Chlordane. Material is considered to be scheduled chemical waste if it contains one or more of the listed 24 compounds where the total concentration of those constituents is more than one milligram per kilogram (or one part per million).
Arising from the extensive excavation and remediation works during the initial development of infrastructure at Sydney Olympic Park, approximately 400 tonnes of contaminated material was stockpiled in a secure area.
In 1999 the NSW Environment Protection Authority (EPA) issued the Authority with a licence under the Environmentally Hazardous Chemicals Act (1985) to treat this waste material.
In determining the appropriate treatment process, the Authority undertook extensive consultation with national and local stakeholders. A summary of the proposed treatment process was advertised in state and local newspapers inviting submissions from the local community.
The Authority also consulted with members of the Homebush Bay Environmental Reference Group. This group included community representatives, academics and environmental non-government organisations and was established to facilitate public communication in relation to remediation activities occurring at the Park.
The treatment process occured in two stages - Indirect Thermal Desorption (ITD) and Base Catalysed Destruction (BCD). Prior to developing this technology, the only option was the permanent storage of highly contaminated materials in secure warehousing. The EPA, the Homebush Bay Environmental Reference Group and various environmental organisations endorsed the treatment process.
The treatment process can be simply summarised as:
- in August 1999 the stockpiled waste material was sorted, mechanically screened and crushed
- the Stage 1 ITD process commenced in September 1999 and used heat to separate the concentrated chemical waste from the soil. End products included: treated residual soil, water and a concentrated chemical sludge (stockpiled for treatment in Stage 2 of the process)
- the Stage 2 BCD treatment process destroyed concentrated waste by reversing the chemistry used to manufacture them initially. End products of the Stage 2 treatment process included: salt, caustic soda, water and carbon in a carrier oil.
In accordance with the EPA Licence, environmental monitoring of dust, vapours, noise and water occurred throughout the project.
The Stage 2 treatment was completed in May 2002. Approximately 37,000kg of highly concentrated material, some in the order of 900,000 parts per million (ppm), was treated down to a final aggregated concentration of less than 1 part per million. Under the Scheduled Chemical Waste Chemical Control Order, this treated material was no longer classified as scheduled chemical waste.
With the completion of treatment of the waste, all residual materials were disposed to appropriately licensed facilities and the final site validation processes and documentation were completed (March 2003) with final sign off from the Independent Site Auditor received 3 April 2003.