The Department of State Development (DSD) letterbox dropped in April 2015 approximately 300 residential and commercial properties to the north, northwest and west of the former Marleston TAFE campus, to update on the results of soil vapour sampling undertaken earlier this year.
This testing was undertaken to confirm the results of the initial soil vapour sampling undertaken in February 2014. The results of the January and March 2015 sampling have been provided to an independent site contamination auditor for review and the auditor has advised that 'there remains no unacceptable risks to residential properties in the vicinity of the TAFE site'.
The letterbox drop follows communication in July by DSD to residents and commercial properties in the assessment area of the results of the initial soil vapour sampling undertaken in residential areas during February this year.
Earlier on 14 July 2014 the DSD, formerly the Department of Further Education, Employment, Science and Technology (DFEEST), advised residents of the results of soil vapour sampling that was undertaken by the site contamination consultant in February 2014.
The independent site contamination auditor engaged by DSD has reviewed the assessment undertaken by the consultant and has provided preliminary advice in relation to the soil vapour sampling. The site contamination auditor’s advice is that the risk to human health from the inhalation of trichloroethene (TCE) vapours in offsite residential areas adjacent the site is low and acceptable. The auditor has indicated that some data gaps are still present and investigation and risk assessment work is ongoing.
Residents and commercial properties were advised by DSD that further assessment will be undertaken and results from this work will be communicated to property owners. Residents were also reminded not to use bore water for any purpose until further notice. Mains water and rainwater tanks are not affected.
Environmental assessments at the former Marleston TAFE Campus have been ongoing since 2010 to determine the extent of groundwater contamination located on and offsite. The chemicals identified in groundwater are trichloroethene (TCE), perchloroethene (PCE) and dichloroethene (DCE) and have been detected in concentrations above the World Health Organization drinking water guideline values. TCE and PCE are industrial solvents used widely as a metal cleaner and degreaser, and DCE is a breakdown product of PCE and TCE.
The purpose of the soil vapour sampling was to determine whether or not the chemical substances present in the groundwater are also present in the soil pore spaces. The chemical substances in the groundwater have the potential to migrate from the groundwater through the soil as a gas (vapour).
TAFE SA first informed properties within the vicinity of the known groundwater in February 2011, further updates were provided to the residents and commercial properties in December 2012 and 2013. TAFE SA has now vacated the site and DSD will engage the consultant to undertake further assessment at the site and the surrounding area of Marleston, West Richmond and Richmond. This assessment will be reviewed by the independent site contamination auditor engaged by DSD.
For further information the EPA can be contacted on 08 8204 2004 or via email.
Letter to residents
Frequently asked questions
How did the EPA become aware of the contamination?
The EPA was first notified in June 2010 by consultants commissioned by the Department of Further Education, Employment, Science and Technology (DFEEST) to undertake environmental assessments on a portion of the TAFE SA Marleston campus. The chemicals of concern include trichloroethene (TCE), tetrachloroethylene (PCE) and dichloroethene (DCE).
What recent work has been undertaken?
In February 2014, the consultant engaged by DFEEST undertook soil vapour sampling and further groundwater sampling in the area of the identified groundwater contamination. The assessment included the installation of boreholes on council road verges in Marleston, Richmond and West Richmond.
The purpose of the soil vapour sampling was to determine if the chemical substances present in groundwater are also present in the soil pore spaces. The additional groundwater sampling was undertaken on site to investigate potential sources of the contamination.
The most recent groundwater sampling undertaken by the site contamination consultant in February 2014 indicated that the groundwater contamination plume extends in a nortwesterly direction from the Marleston TAFE SA campus to Salisbury St, West Richmond and Bignell St, Richmond.
The consultant has prepared a Preliminary Soil Vapour and Groundwater Risk Assessment Report. The independent site contamination auditor engaged by the Department of State Development (DSD, formerly DFEEST) has reviewed the report prepared by the consultant.
DSD has provided to the EPA the site contamination auditor’s written advice that he is of the opinion that the risk to human health from the inhalation of trichloroethene (TCE) vapours in the offsite residential areas adjacent the site is low and acceptable. The auditor has indicated that some data gaps are still present and investigation and risk assessment work is still ongoing.
What work is to be undertaken?
DSD has advised the EPA that further assessment will be undertaken in the area according with the auditor’s recommendations, and results from this work will also be communicated to property owners.
The EPA will continue to oversee all of the assessment and any remediation that is undertaken at the site and will continue to engage with DSD to ensure both on and offsite risks are managed.
How long has the contamination been present?
The contamination is historical in nature and arose from the use of TCE and PCE solvents that were considered historically acceptable at the time. It is likely that the contamination was caused progressively from the use and storage of these chemical substances as well as other activities undertaken in the vicinity of the TAFE SA Marleston Campus.
The disposal of chemicals on land was a common practice on many historical industrial sites. Once in the soil, these chemicals can move down to the water table and contaminate groundwater. DFEEST has not contributed to the contamination as the owner of the site.
What are TCE, PCE and DCE?
TCE and PCE are common industrial solvents and were used widely as degreasers and metal cleaners. DCE is generally present as the result of the degradation and breakdown of TCE and PCE.
For more information on the chemicals of concern, please refer to SA Health Chlorinated solvents in groundwater.
What is the problem posed by PCE, TCE and its breakdown products (DCE)?
The chemical substances found to be present in groundwater have the potential to change from liquid to gas (vapour phase) and move into soil pore 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 buildings. If ventilation is low, vapours may then accumulate within building spaces and be inhaled by persons in the building. The risk posed by these chemicals in commercial/industrial properties and homes would be through long-term exposure.
How did PCE and the other related chemicals get into the groundwater?
TCE and PCE and its breakdown products are liquid chemicals that readily flow and evaporate when released to the environment. Depending on how the chemicals were introduced to the soil, and the geology of the underlying soil and rock, it is possible that these chemicals migrated through the pores in the soil, dissolved in water and then flowed down gradient in the groundwater or became present through breakdown chemical reactions.
Liquid PCE and TCE are denser than water and will sink down through water until it reaches an impermeable barrier. In their pure forms they will then flow along preferential pathways via gravity or pool in confined areas. PCE and TCE that are dissolved in water will migrate with the groundwater in the general direction of groundwater flow.
Can I use the bore water?
The EPA advises residents and property owners to not use bore water until further notice. For example, the bore water should not be used for drinking, irrigation or any other uses.
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, in showers, swimming pools and gardens (via ingestion, inhalation or through the skin). The contaminated groundwater is approximately 6-8metres below ground surface.
What happens when TCE enters the human body or the environment?
For information regarding the TCE or chlorinated hydrocarbons entering the human body, please refer to the SA Health factsheet.
In the environment, TCE breaks down rapidly in air and surface water but much slower in soil and groundwater. TCE breaks down into DCE and then VC (vinyl chloride) which can then degrade to other products.
Are we exposed to TCE, PCE and other related chemicals in the community?
Exposures to these chemicals may occur in the general community, for example, TCE can be found in some household products such as correction fluid, paint or spot removers.
DCE exposure can result from the use of perfumes, lacquers and some plastics (eg thermoplastics). These types of exposures are referred to as background exposures. As exposures to chemicals occur from many sources in our everyday life, it is important that when there is a chance of exposure occurring that can be reduced or eliminated, action is taken.
It needs to be recognised that exposure to any one chemical often occurs from many sources to varying degrees and it is important to reduce total exposures to the lowest amount possible. This is to ensure that total exposure levels are below those that may produce effects on health.
Can I eat my fruit and vegetables?
If you have been watering your fruit and vegetables with bore water, SA Health advises that you should not eat them.
In areas impacted by TCE contaminated groundwater, home-grown produce are safe and do not pose an appreciable risk to residents who consume them, provided they are not watered with contaminated groundwater.
Will my fruit trees be affected?
SA Health assessment of the available literature indicates that the likelihood is low of fruits and vegetables grown in soil near contaminated groundwater containing TCE and related compounds at levels that might represent a risk to health.
For further information the EPA can be contacted on 1800 729 175 or via email.