FAQs – Contaminated Sites

Contamination is any material (e.g. chemicals/ waste) or energy (e.g. heat) which is present above an acceptable level in the environment (e.g. in or on the land surface, in surface water, or in groundwater). Examples include hydrocarbon fuels, metals, asbestos, bacteria, domestic and industrial wastes etc.

There is a legal requirement for an owner/ occupier or person who may have caused or contributed to the contamination, to report a known or suspected contaminated site to the Department of Environmental Regulation (DER), under the Contaminated Sites Act, 2003.

You should employ a reputable environmental consultant to undertake a study; a list of some reputable consultants in WA may be found at the ACLCA-WA websitehttp://www.aclca-wa.org.au. The desk study may include a desk study of the site history (Preliminary Site Investigation (PSI)), and possibly investigation of the site (Detailed Site Investigation (DSI)).

This will depend on the current or proposed future use; if contaminants are present above threshold concentrations designated for different land uses, then a memorial advising of the contamination status will be placed on the Certificate of Title. Remedial works may be necessary to make the site suitable for the intended usage, which may allow the memorial to be removed.

PASS is any material (e.g. soils/ rock) which contains pyritic material (e.g. Iron sulfide, FeS2) in an un-oxidised state, which may release excess acidity, sulfate and metals due to oxidisation by exposure to air (e.g. by excavation, or lowering of the water table).

ASS is any material (e.g. soils/ rock) which contains partially or fully oxidised pyritic material (due to oxidisation by exposure to air (e.g. by excavation, or lowering of the water table)) and which has or is currently releasing excess acidity, sulfate and metals.

Monitoring the progress of the destruction of a contaminant via natural processes (e.g. microbial consumption). It should reduce the mass and concentration of a contaminant to an acceptable level (clean-up goal) within 30-years (inter-generational equality). The process should be understood, demonstrated to be occurring at an acceptable rate, and a fall-back (contingency) plan should be provided where MNA fails to meet the remedial objectives.

The typical stages may include the following, depending on the complexity/ size/ risk/ sensitivity associated with the site:

Stage 1: Preliminary Site Assessment (PSI); desk appraisal of site history
Stage 2: Detailed Site Investigation (DSI); investigation to fully characterise site contamination and assess the associated risk to human health and the environment
Stage 3: Remediation Action Plan (RAP); develop a plan to address/ manage unacceptable known contamination, including remedial and validation objectives

Stage 4: Site Remediation and Validation (SRV); develop a methodology to manage or remediate the identified contamination, to make the site suitable for its current and proposed use.
Stage 5: Site Management Plan (SMP): A plan to manage and monitor the remediation works, to ensure that no unacceptable impacts occur. This may include et. Al dust/ odours, water management, noise, stockpiling and transport of materials.

Stage 1: Preliminary Site Assessment (PSI); desk appraisal of site history
Stage 2: Detailed Site Investigation (DSI); investigation to fully characterise site contamination and assess the associated risk to human health and the environment
Stage 3: Site Management Plan (SMP); develop a methodology to manage or remediate the identified contamination, to make the site suitable for its current and proposed use.
Stage 4: Remediation, Validation and On-going Management (RVOM): Remedial works are undertaken, validated to show that they have successfully achieved the remedial goals, and any requirements for ongoing management (e.g. monitoring, maintenance of cover layers etc).