State of the Environment Report 2007
Land contamination is defined as land that has a pollutant (or pollutants) at above-background concentrations causing, or with the potential to cause, adverse impacts to human health, the environment or any environmental value. For this issue, 'pollutants' refers to chemicals such as heavy metals, pesticides, herbicides, oils, hydrocarbons and other toxic chemicals.
The toxicity and persistence of pollutants in soils, as well as their direct uptake by people, plants and animals, is the major concern with land contamination. The extent and severity of contamination will depend on pollutant type, land uses and industries, soil types and the effectiveness of pollution controls, if any exist. If the pollutant does not adhere to soil particles it may be mobilised by wind and water flow, or leached by soil water and transported by groundwater flow. For this reason, contaminated sites may cause both on-site and off-site environmental impacts. Contaminated sites are usually identified after the polluting activity or land use has ceased and the land is being redeveloped for another use. Some contaminated sites are identified once groundwater pollutant plumes are detected in inland waters or bore water.
Soil pollutants can affect human, plant and animal health if direct contact is made with contaminated soils or water, or if inhalation of chemical vapours and contaminated dust occurs. Impacts may vary in severity from reduced growth and reproduction to sickness, mutations and, in extreme cases, death. The effect of some toxic pollutants is increased by their ability to persist and build up in the environment over a very long period of time.
The Contaminated Sites Act 2003 identifies a specific objective to:
and identifies a principle that:
The actual number of contaminated sites in WA is difficult to determine. In 1995 it was estimated there were 1500 sites, with about 80% thought to be on the Swan Coastal Plain as a result of extensive land development, and major industry and manufacturing operations. New regulations under the Contaminated Sites Act 2003 have enabled better identification of contaminated sites in WA, through mandatory reporting of known or suspected contaminated sites. Although the Department of Environment and Conservation has a database of suspected contaminated sites, many require further investigation to clarify whether they are actually contaminated. As of March 2007, 1358 contaminated sites had been formally reported to the department. A significant number of additional sites is expected to be reported in 2007, to meet mandatory reporting requirements.
Known contaminated sites are mostly linked to past land uses for heavy industry, service stations, power stations, gasworks, landfill sites, mine sites, chemically intensive industries and some agricultural land uses (e.g. feedlots, market gardens). Service industries and the oil, petroleum and energy sectors currently account for over two-thirds of new contaminated sites identified (Figure L4.1). A high number of contaminated sites associated with the services sector can be attributed to land redevelopment. Remediation and treatment activities are normally required to ensure future land uses are not at risk of contamination.
![Figure L4.1: Proportion of identified Western Australian contaminated sites by sector. [Data source: Department of Environment and Conservation.]](/site/files/images/Figure-L4.1_Large.jpg)
There has been a trend towards increasing identification of contaminated sites since the early 1990s (Figure L4.2). Most of this increase can be attributed to greater awareness and identification of contaminated sites in relation to land redevelopment. Since 1992, improved leak detection capability for underground storage tanks of petrol stations has also led to improved identification of contaminated sites. A peak in 2004 is due to the identification of about 180 individual sites as a result of the Northbridge Redevelopment Project in Perth. New regulations for the Contaminated Sites Act 2003 became operational in December 2006, and is expected to result in a dramatic increase in the number of contaminated sites recorded in 2007.
![Figure L4.2: Number of contaminated sites reported to the Department of Environment and Conservation, 1992–2006. [Data source: Department of Environment and Conservation.]](/site/files/images/Figure-L4.2_Large.jpg)
The main causes of land contamination are poor or inadequate practices linked with the manufacture, use and disposal of chemicals by past or current industrial, agricultural or commercial activities. Point (local scale) contamination sources include chemical spillage, leakage of chemicals from landfill sites, storage drums, tanks, pipes and drains. Leakage of chemicals often occurs during industrial plant operation, storage or transportation. The main contaminants from industrial operations or waste that have potential to contaminate land include acids, alkalis, metals, surfactants, solvents and organic chemicals (such as phthalates, phenols, oils, aromatics, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, halogenated aliphatics, pesticides, radionuclides and biological contaminants). Diffuse (broad scale) contamination sources usually include leaching of contaminants from widespread application of pesticides and fertilisers.
Deliberate dumping of waste by-products because it is cheaper and easier can be environmentally damaging and harmful to human health. It can also be especially difficult and costly to clean up and may result in offenders being prosecuted.
Mining activities, such as constructed tailings storage dams and some disused mine sites, have the potential to contaminate land if managed or constructed inappropriately. Many tailings deposits are not built as engineered structures, but simply through piling up of tailings slurries. Depending on the nature of the mining operation and extractive processes, these tailings may contain acidic or caustic material, heavy metals or cyanide, generally rendering the land unsuitable for any other future land use. Mine pits may become contaminated due to acidic water, potentially carrying high levels of dissolved heavy metals, infiltrating the pit. They are likely to remain contaminated in the absence of extensive rehabilitation measures.
Historical use and improper disposal of pesticides has been a leading cause of contaminated sites. Pesticide operators are licensed, and pest control businesses regulated, by the Department of Health to prevent further contamination occurring. As of March 2007, there were 1664 licensed operators and 686 pest control businesses in WA. The number of operators has grown significantly in recent years, in response to favourable economic conditions and the property boom. The rising number of operators indicates that pesticide and herbicide use is increasing. Synthetic pyrethroids and organophosphates are the pesticides now favoured by operators, and are considerably less toxic and persistent in the environment than pesticides used several decades ago (Department of Health, unpublished).
Accidental spillage of hazardous chemicals, or biological or radioactive materials infrequently occurs following inappropriate storage, handling or transportation. Statistics indicate about 70 emergency events occur every year that involve hazardous materials (Fire and Emergency Services Authority, 2005). Many of these involve fires and chemical spills that may present some risk of land or water contamination.
There are currently about 6500 licensed sites in WA where hazardous chemicals are stored (Department of Consumer and Employment Protection, unpublished). While every attempt is made to store hazardous chemicals safely on licensed premises, inevitably there is a risk of spillage. Where spillages are significant or of a serious nature they may present a contamination issue if cleanup and remediation actions are not adequate.
Contaminated Sites Act 2003: The purpose of the Act is to enable and facilitate identification, management and remediation of contaminated sites. It uses the 'polluter pays principle', which attaches liability initially to the polluter, then the landowner or occupier, and finally the State Government. The Department of Environment and Conservation is responsible for administering the Act and associated regulations.
Soil and groundwater remediation research: Projects are being undertaken by CSIRO to develop innovative technologies for the investigation, assessment and remediation of contaminated groundwater, water and soils.
Management guidelines for contaminated sites: The Department of Environment and Conservation has released a series of documents addressing identification, assessment, remediation methods, monitoring, community consultation, land use planning, and management and reporting in relation to contaminated sites. In addition, a number of guidelines have been developed to provide advice on the management of contaminating activities situated on, or near, groundwater protection areas.
National programs: There are a number of national programs such as the River Contaminants Program, the National Groundwater Research and Development Program and the National Pollutant Inventory which are directed at identifying and reducing pollutants being discharged to the environment.
Assessment of site contamination: The National Environment Protection (Assessment of Site Contamination) Measure 1999 forms the basis of many WA guidelines. This measure was developed by the Commonwealth Government to establish a consistent method for assessment of contaminated sites, so as to ensure sound environmental management practices for protection of human health and the environment (National Environment Protection Council, 1999).
Contaminated Sites Committee: is a statutory committee comprised of environmental and legal experts who are responsible for deciding appeals and for prioritising and remediating orphan or State-owned sites.
Contaminated site remediation: Land Corp is responsible for the remediation of orphan sites on behalf of the State Government. For other privately owned sites it is the responsibility of the polluter, land owner or occupier to clean up a contaminated site.
Planning conditions: The Western Australian Planning Commission and local government planning authorities are responsible for placing conditions on subdivision, rezoning, building and other planning applications where contamination requires investigation and/or remediation before development occurs.
Environmental implications of contamination may be short-lived or persistent, depending on the nature of the pollutant and the extent of its spread through the environment. Persistent chemicals such as heavy metals, pesticides, herbicides and some biological and radioactive agents pose the greatest risk to people, flora and fauna. The environmental repercussions of land contamination are extremely serious and may lead to a variety of complications, from sickness, to cancer and mutations, to widespread death of flora and fauna. Health effects of pollutants may be acute (short-lasting) or chronic (long-lasting), and be localised (in the vicinity of contaminated site) or widespread, affecting nearby populations (epidemic). Severe contamination may also render some land uninhabitable and severely constrain land use options for decades to centuries.
Remediation of contaminated sites is generally expensive but the economic costs of land contamination far outweigh the cost of remediation. For example, site cleanup costs incurred by government for the former East Perth Gas Works were $17.5 million, and for the former fertiliser plant at Minim Cove in Mosman Park was $16 million. Even relatively simple situations can be costly, such as the cleanup of drums containing oil and the herbicide 2,4,5-T at several bush sites near Dwellingup, which was estimated to cost $500 000. Contamination of land can also contribute to decreased property values and affect future potential land use capability. For example, the old Causeway Bus Depot site fell in value by nearly $9 million because of evidence of land contamination (Auditor General for Western Australia, 2002). The social ramifications of land contamination are significant. Discovery of a contaminated site in, or close to, residential areas may cause considerable community concern and distress, irrespective of the risk of potential exposure to the contaminant (e.g. the Brookdale incident of 2002).
3.10 The Contaminated Sites Act 2003 and supporting regulations are now fully operational. Continue to implement the Act and regulations including the verification of suspected contaminated sites and their remediation.
