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GM Holden enters into a voluntary site contamination assessment proposal
The EPA and Holden entered into a voluntary site contamination assessment proposal (VSCAP) on 22 November 2016, which provided a framework and set of defined deliverables for the assessment of the nature and extent site contamination (on and off site) as a result of Holden activities at the site. Holden satisfied the terms of the VSCAP in February 2019 with the delivery of a site contamination audit report.
Details of the VSCAP are publicly available on the public register.
Archived
Community engagement
Holden has established a community reference group of key community representatives from local government, schools, not-for-profit organisations and businesses located in the Salisbury and Playford areas.
The group wasscheduled to meet every 3 months to share information so that the community is up to date on Holden’s activities and can give feedback on these activities.
Letters to residents
Media releases
Background
Holden have been undertaking various site contamination assessment and remedial works at the site since 1999, generally as a result of events resulting in environmental harm or site contamination (ie release of chemicals to the environment as a result of failure of infrastructure or spill events). The EPA regulated Holden to ensure all site contamination assessment and remedial works undertaken have been adequate.
An EPA accredited site contamination auditor was engaged to audit the environmental assessment works and prepare a site contamination audit report for the site since March 2012.
The EPA and Holden entered into a voluntary site contamination assessment proposal (VSCAP) on 22 November 2016, which provides a framework and set of defined deliverables for the assessment of the nature and extent site contamination on and off-site as a result of Holden’s activities at the site. The term of the VSCAP was 2 years.
The site contamination audit report will be provided as the final deliverable of the VSCAP, with the report to detail the nature and extent of site contamination (on and off-site) and what remediation is or remains necessary for a specified use. The site contamination audit report will be publicly available on the EPA’s public register, once available.
On completion of the VSCAP and based on the conclusions of the site contamination audit report, Holden will provide the EPA a detailed plan for the remediation of site contamination which poses an unacceptable risk to human health and the environment on and off-site.
The Environment Protection Act 1993 provides the EPA the power to require Holden to undertake all required environmental assessment work including remediation, if it fails to comply with its obligations under the Act and the VSCAP. Holden has to date has met its obligations as agreed to under the VSCAP.
Ground (bore) water contamination
The EPA is aware of contamination of underground water beneath and down hydraulic gradient of the site. Based on information held by the EPA the main contaminants of concern in groundwater are primarily, but not limited to, chlorinated hydrocarbons, specifically trichloroethylene (TCE), tetrachloroethylene (PCE), dichloroethene (DCE) and vinyl chloride (VC).
On 23 January 2012 Holden notified the EPA of elevated concentrations of TCE and PCE in groundwater to north of the site, which extended beneath the residential areas to the north of the site. Following assessment of nature and extent of the identified TCE and PCE concentrations, it was identified that a potential vapour intrusion risk may have existed beneath a select portion of the residential properties to the north.
As the chlorinated hydrocarbons are known to present vapour plumes, the environmental consultant commenced a targeted soil vapour sampling program on road verges and council land in early July 2012. Holden completed crawl space testing at a number of residential properties in August 2012 and February 2013 to assess the potential vapour risk, under the supervision of its site contamination auditor.
The soil vapour and crawl space testing determined that the potential for vapour intrusion at the residential properties and risk to human health is considered to be low and acceptable.
The 2 rounds of crawl space testing was completed to ensure seasonal variability was not influencing the measured concentrations of vapour in the crawl spaces. Both rounds of testing identified TCE and PCE at levels below the adopted site-specific health screening criteria.
Holden door knocked the 20 residential properties in May 2013, and letterbox-dropped a further 75 residents to advise of the results of the testing.
Further assessment of groundwater contamination is continuing by Holden, as required by the VSCAP. Holden will continue to keep residents well informed of any further assessment results.
The EPA and Holden have advised all land owners within the assessment area to not use groundwater for any purpose, unless it has been tested and determined to be fit for purpose.
Frequently asked questions
What are TCE, PCE, DCE and VC?
TCE and PCE are common industrial solvents and were used widely as degreasers and metal cleaners. For more information on the chemicals of concern, please refer to SA Health.
Chlorinated hydrocarbons are a widespread contaminant of groundwater around the world. SA Health consistently advises all South Australians not to use bore water unless they have had the water adequately and frequently tested and it is shown to be safe for its intended use.
What is the problem posed by PCE, TCE and its breakdown products (DCE and vinyl chloride)?
The chemical substances found to be present in groundwater also have the potential to change from liquid to gas (vapour phase) and move through pore spaces in the soil to the ground surface. It is then possible for the vapours to further migrate and build up in confined spaces such as cellars, houses and basement car-parks. The risk posed by these chemicals in commercial/industrial properties and homes would be through long-term exposure.
Exposure can occur if the chemicals migrate through the soil pore spaces to the ground surface, and then find their way through crawl spaces, cracks and holes in the slab, floor or walls of the building. If ventilation is low, vapours may then accumulate within building spaces and be inhaled by persons in the building.
Why is it necessary to collect samples of the air in crawl spaces of people’s homes?
As the chemicals are volatile in nature (ie they are present in a gas phase), they have the potential to migrate through the soil and into confined spaces ie crawl spaces.
Exposure can occur if the chemicals migrate through the soil pore spaces to the ground surface, and then find their way through crawl spaces, cracks and holes in the slab, floor or walls of the building. If ventilation is low, vapours may then accumulate within building spaces and be inhaled by persons in the building.
Previous air samples were collected from the crawl spaces of homes and sent to a specialist interstate laboratory for chemical analysis. The site contamination consultant prepared a risk assessment which was provided to the site contamination auditor and the EPA.
The outcome of the assessment was that concentrations of TCE and PCE are all below the site specific health screening levels that have been approved by the independent site contamination auditor for all crawl spaces tested. Ambient air was also tested which identified similar results to the crawl space testing results.
It should also be noted that people are exposed to ‘background exposures’ in our everyday life (see the FAQ ‘Are we exposed to TCE and its breakdown products in the community?’).
How long has the contamination been present?
The contamination is historical in nature and arose from the use of TCE and PCE solvents that for a number of historic activities that were considered acceptable at the time. It is likely that the contamination was caused progressively from the use of these chemical substances for cleaning metal parts and plastics, as well as for dry cleaning at the site. At this stage, the source of the contamination has not been confirmed.
Can I use bore water for any use?
The EPA and SA Health advise residents and property owners to not use bore water for any use until further notice. For example, the bore water in the area should not be used for drinking, irrigation or any other uses until further notice is provided by the EPA.
If you are outside the investigation area, you should still have your bore water tested. Even if these bores are not affected by industrial pollutants, bore water can be contaminated by other sources such as historical agricultural and horticultural activities and fuel storage. It is also possible for bore water to be unsuitable for use because of the presence of naturally occurring chemicals.
How can contact with these chemical substances occur if they are in groundwater (bore water)?
Exposure occurs through using contaminated groundwater for drinking or cooking, and in showers, swimming pools and gardens (via ingestion, inhalation or through the skin). The contaminated groundwater is approximately 18–20 m below ground surface.
