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What is site contamination?

Contamination, in relation to land, water or a site, means having a substance present in or on that land, water or site at above background concentrations that presents, or has the potential to present, a risk of harm to human health, the environment or any environmental value (Contaminated Sites Act 2003).

The Contaminated Sites Act 2003 (CS Act) was introduced to identify, record, manage and clean up contamination in Western Australia. Land owners, occupiers and polluters must report known or suspected contaminated sites to the Department of Water and Environmental Regulation (DWER).

What is DWER's role around site contamination?

Investigating and cleaning up contaminated sites is, in most cases, the responsibility of the polluter or current site owner. DWER administers and enforces the CS Act and Contaminated Sites Regulations 2006. This includes classifying sites (in consultation with the Department of Health) and making information on contaminated sites available to the public. 

If a site is contaminated, is there a risk to the public?

For a risk from site contamination to exist, all three of the following elements must exist:

  • a source (e.g. contaminated groundwater)
  • a pathway  (e.g. use of bore water)
  • a receptor (e.g. residents)

There are many ways that site contamination can be managed—there is no ‘one size fits all’ approach and each case is assessed individually. The determination of whether an unacceptable risk from site contamination exists depends on a range of factors, including whether or not the current or proposed land use is considered sensitive, such as residential properties or schools. 

In some cases the way to minimise and manage risk is to remove one of the three elements – for example, if the pathway is removed then the risk to the public is reduced or removed. An example would be managing contaminated groundwater by ensuring that bores are not permitted within the contaminated area, preventing access to that water source.

Sometimes sites can be cleaned up by removing the source, such as removing contaminated soil, or by putting physical barriers between the contamination and people, thus removing the pathway. However, sometimes the nature of contaminants, their location or their extent, may mean that a complete site clean-up is not practicably possible and the contamination may need to be managed on an ongoing basis.