Under the Environment Protection Act 1993 (EP Act), known or suspected groundwater contamination must be reported to the EPA. The authority can then require assessment, and if necessary remediation which means to treat, contain, remove or manage the contamination.
The EPA is working to manage site contamination across South Australia as part of the State Government’s strategic priority to deal with long-term environmental and health impacts of historic pollution. Scientific understanding and technologies to assess and remediate site contamination are constantly improving. The EPA also works with other regulators in Australia and overseas to improve knowledge and expertise in managing legacy contamination.
The EPA takes a risk-based approach for the assessment and remediation of groundwater contamination to ensure the protection of human health and the environment. This allows for a site to be remediated to a level that matches the future intended land use, for example as industrial, commercial or high density residential use. While it is not economically feasible to remediate every contaminated site, the EPA prioritises sites that are contaminated to an extent they present a potential risk to health or the environment.
Site contamination provisions
The EPA administers and enforces the EP Act to ensure responsible persons undertake this work appropriately. It also makes information on contaminated sites available to the public through the public register.
Pollution of the environment has been an offence since 1995, when the EP Act came into operation. Where there is sufficient evidence, the EPA can prosecute the polluter, provided the polluting activity occurred after May 1995.
Responsibility for site contamination is assigned according to the polluter pays principle – this means that the original polluter is liable for any clean-up and associated costs caused on and off the source site, regardless of when it was caused.
In most cases, the original polluter, or the past or current site owner must undertake or fund this work, including communicating with affected residents to keep neighboring property owners informed. Understanding the timing of the contamination and identifying the polluter are not always possible, and in some cases companies identified as past polluters may no longer exist.
Investigating and cleaning up contaminated sites can be expensive. Prospective land purchasers should be aware of the risk of potential contamination and carry out careful, thorough pre-purchase enquiries known as the ‘due diligence’ process.
When buying, selling or leasing property, you and/or your real estate agent should research the information held by the EPA as part of any routine due diligence enquiry:
Chemicals of concern
In order for site contamination to pose a potential health risk, there needs to be a pathway from the source to the environmental or human receptor. When site contamination affecting the soil has been remediated, sometimes a residual risk to residents comes from contamination that affects the groundwater on or off the site.
Site contamination affecting groundwater can contain chemicals such as heavy metals, volatile organic compounds (petroleum hydrocarbons, chlorinated solvents such as TCE and PCE), pesticides, polycyclic aromatic hydrocarbons and nitrates. If groundwater is affected by contamination it can be harmful to human health if extracted via a bore. In other circumstances contaminated vapour from the groundwater can enter residential indoor air.
SA Health provides advice to the EPA on the assessment of environmental contaminants that may be harmful to human health, and advises of the likely effects on impacted communities. Both agencies regularly review international scientific literature to ensure the most up to date assessments are made in regards to the potential health impacts on a community.
Trichloroethene, also known as trichloroethylene or TCE is a colourless liquid industrial chemical that is used widely in industry for metal cleaning and in production of products such as adhesives, lacquers, dyes, perfumes and soaps.
In the past, TCE was also used in many other applications such as removing caffeine from coffee beans in the production of decaffeinated coffee, in dry cleaning and as an anaesthetic for surgery.
SA Health has developed an indoor air level response range for the chemical trichloroethene (TCE). This provides a consistent response for the EPA, environmental consultants and auditors, when TCE is found or predicted to be found in residential homes through vapour intrusion. This is a conservative approach to protect the most vulnerable members of the community, and was developed and independently reviewed by national and international experts.
Tetrachloroethene, also known as tetrachloroethylene, perchloroethene or PCE is a colourless liquid industrial chemical that is widely used for dry cleaning fabrics and for metal cleaning. It is also used to make other chemicals and is used in some consumer products.
Benzene in its pure form is a colourless liquid with a sweet (aromatic) odour. Crude oil is the largest natural source of benzene, with petrol in Australia now containing about 1% by volume of this aromatic hydrocarbon.
Benzene is widely used by industry in the manufacture of many products including plastics, synthetic rubber, glues, paints, furniture wax, lubricants, dyes, detergents, pesticides, and pharmaceuticals. The International Agency for Research on Cancer (IARC) has established that benzene can cause cancer in humans.
Exposure to benzene typically occurs by breathing in air containing benzene vapour. Benzene evaporates into the air very quickly and is readily absorbed into the body from the lungs. In addition, skin contact or ingestion of benzene-contaminated water will result in absorption by the body.
Some forms of chromium are essential for the human body to function while other forms are toxic to humans. Exposure to toxic forms of chromium can occur in some work environments and sometimes in the general population due to contamination of our environment.
Hexavalent chromium, (chromium VI) rarely occurs naturally, and is mostly produced and released into the environment by human activities. Hexavalent chromium can be an impurity in Portland cement and in tattoo inks. It can also be generated in industrial processes involving stainless steel (casting, welding and cutting).
Hexavalent chromium compounds are used widely in many industrial applications and can contaminate groundwater below where it was used. If food or water was contaminated with hexavalent chromium then health effects may occur.
Per- and poly-fluoroalkyl substances, known as PFAS, are man-made chemicals that have been used in a range of industrial and consumer products since the 1950s.
PFAS have been used in domestic and commercial applications including in the manufacturing of non-stick cookware, in stain protection for fabrics, furniture and carpet, in food packaging and predominantly in some types of fire-fighting foams.
For the majority of South Australians, mains water (tap water) is not sourced from groundwater and is safe. In some regional areas where mains water is sourced from groundwater in South Australia, PFAS contamination is not present.
Soil vapour contamination
It has long been understood that some chemicals can be transported in groundwater for thousands of metres. More recently it has been discovered that they can also be found in the air spaces between soil particles as vapour. The science and understanding of soil vapour contamination has significantly increased over recent years.
Chemicals including petrols and solvents like trichloroethene (TCE), dichloroethene and vinyl chloride are termed ‘volatile’, are extremely common and have been used historically both domestically and industrially. Volatile chemicals, or ‘volatile organic compounds (VOCs) are commonly found in petrol, some glues and paints, some cleaning products and some degreasers.
When volatile chemicals are present close to residential properties, contaminated vapour can intrude into homes through small pathways, such as cracks in foundations or floorboards. This is called ‘vapour intrusion’. If these chemicals are present inside buildings at high enough concentrations over extended periods of time, they can potentially result in adverse effects to your health.
Mitigating vapour intrusion
In the rare instance that a home is affected by soil vapour intrusion, the EPA works with responsible persons to assist residents to manage any health risk.
As part of what is believed to be an Australian first, the EPA has successfully installed vapour mitigation systems in several homes in metropolitan Adelaide. The systems have reduced the vapour contamination in indoor air to within safe levels.
A typical vapour mitigation system (see pictures) consists of one or more 300-mm fans connected to a network of pipes. The pipes are installed below a concrete slab or within the crawl space beneath the flooring, depending on the house construction type.
The pipes take the vapour contamination from underneath the house and extract it to the atmosphere through a small vent mounted on the roof. In order to successfully remove indoor air contamination, the system must run 24 hours a day, 7 days a week. Each system is designed specifically for the construction type of a house.
Indoor air level response range
The EPA uses an ‘Indoor air level response range’ where key volatile chemicals have been found to enter indoor air in quantities that SA Health considers may not be confirmed as safe.The indoor air levels for trichloroethene (TCE) and tetrachloroethene (PCE) determine whether or not indoor air contamination is in high enough quantities to warrant the installation of a vapour mitigation system.
- Indoor air level response range (TCE)
- Interim indoor air level response range (PCE)
- Vapour intrusion and mitigation in Beverley, SA
For further information on soil vapour intrusion please contact (08) 8124 4216 or email.
If you have any questions please contact the Site Contamination Branch on (08) 8204 9934.
For SA Health advice from the Scientific Services Branch please phone (08) 8226 7100.