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The Department of Water and Environmental Regulation has produced Acid Sulfate Soil (ASS) risk maps for most coastal regions of WA to identify high risk ASS areas so disturbance and potential environmental damage can be avoided where possible. ASS risk areas are grouped into two classes according to the probability and depth of ASS and potential for disturbance.
Acid sulfate soil (ASS) materials commonly occur in Western Australia's low-lying wetlands, estuaries, salt marshes and tidal flats but are not limited to coastal regions.
Undisturbed, these soils are relatively harmless but when exposed to oxygen, through drainage or excavation, ASS materials produce sulfuric acid in large quantities. Other toxic elements, including arsenic, aluminium and heavy metals, can be generated when ASS materials are exposed to air.
Department of Water and Environmental Regulation has produced ASS risk maps for most coastal regions of WA to help developers, environmental scientists and planners identify and avoid disturbing ASS materials in high risk areas. ASS risk areas are grouped into two classes according to the probability and depth of ASS and potential for disturbance.
- Class 1 – there is a high to moderate risk of disturbing ASS materials at this site. WA Planning Commission will impose an automatic a condition on planning proposals in Class 1 areas.
- Class 2 – there is a moderate to low risk of disturbing ASS materials at this site. However, if site characteristics or local knowledge indicate the potential presence of ASS, further investigations are recommended, particularly if excavating more than 100 cubic metres of soil or carrying out dewatering/drainage works.
For more information on ASS site investigations and access to ASS risk maps see www.der.wa.gov.au/ass or contact Department of Water and Environmental Regulation's information line on 1300 762 982.