Unley

In May 2017, the EPA undertook environmental works in an assessment area bounded by Charles Lane, Little Charles Street, Mary Street and Tyne Place in Unley. The EPA work was undertaken to ensure that the legacy of past industrial practices does not pose a risk to residents living there today.

It has long been understood that volatile chemicals can be transported in groundwater. More recently it has been discovered that they can also be found in the air spaces between soil particles as vapour.

In July 2017, the EPA advised no detections of chemicals in soil vapour above criteria for residential land use were identified. All properties in the Unley assessment area are considered by the EPA to be safe from soil vapour intrusion.

Further sampling of the vapour coming off the groundwater was undertaken during 2019 as a precautionary measure to ensure the potential for it to enter indoor air is clearly understood in one small area. The previous vapour assessments were completed using temporary samplers, and this 3rd stage of work was using permanent bores (see ‘Maps’).

• Stage 3 assessments, March 2019
• Stage 2 assessments, June 2018
• Soil vapour results, July 2017
• Stage 1 assessments, April 2017

• Unley Stage 3 environmental assessmental program, September 2019
• Unley Stage 2 environmental assessmental report, September 2018
• Unley Stage 1 assessment works, passive soil vapour investigations, June 2017

• Community update 4, 24 September 2019 
• Community update 3, 27 March 2019 
• Letter to residents, 4 June 2018
• Letter to residents, 20 July 2017
• Letter to residents, 28 April 2017
• Community update 2, 4 June 2018
• Community update 1, 28 April 2017
• Site contamination overview fact sheet, December 2016
• Indoor air level response range (TCE)
• Key messages

Why is the EPA undertaking assessment work in Unley?

On behalf of the SA Government, the EPA manages the legacy of existing contaminated orphan sites. An orphan site is where the original polluter no longer exists, cannot be found or identified, or is unable to carry out or pay the costs of the assessment or remediation that is required.

The EPA has developed a prioritised work program to investigate sites where it holds enough information to warrant further investigation into whether there is a potential human health risk. The EPA is aware of site contamination in the Unley area resulting from historic industrial and chemical disposal and handling practices.

When groundwater contamination happens near residential properties, these chemicals can potentially enter into homes in vapour form. The information provided historically is incomplete and a number of data gaps have been identified by the EPA.  

At this time it is not known who caused the site contamination. As a result the area is deemed to be an orphan site and the EPA will, on behalf of the community, assess the potential for a human health risk. In order to determine whether soil vapour intrusion is occurring in the Unley assessment area, work to gather more data will assist the EPA in its understanding of the soil vapour composition, and whether any additional assessment work is required. Work is being undertaken in road verges and are not required to be on private properties.

What triggered the EPA assessment?

Assessment of a site under audit adjacent to the EPA assessment area previously identified 49,000 micrograms per cubic metre (μg/m³) of TCE in shallow soil vapour and the auditor notified the EPA of a potential significant hazardous circumstance. This was remediated by the responsible party at the time, and follow up testing identified significantly reduced TCE in shallow soil vapour.

The notification however, indicated there may be an up gradient offsite source. The EPA understands that the same historical activities were likely to have been undertaken elsewhere in the assessment area. The reports held were undertaken over the last decade and the EPA identified a number of data gaps because they were completed prior to soil vapour being considered together with groundwater.

When did the EPA find out about the contamination?

The EPA was notified by an auditor that there may be a potential site of groundwater contamination in 2013. The EPA holds information on almost 2,200 sites that have been listed on the Public Register. 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. While it is not economically feasible to remediate every contaminated site, the EPA prioritises sites that have the potential to present a health or ecological risk and Unley is next on the prioritised work program to undertake further investigations.

What information does the EPA hold in regards to Unley?

The EPA holds a number of site contamination assessment reports for several sites between Charles Lane and Mary Street at Unley. The area comprises a mix of commercial, industrial and residential land. Site contamination is believed to come from historical industrial land uses such as refrigeration manufacturing, furniture manufacturing, cabinet making, boot making and a drapery.

South Australia has a proud manufacturing history and some chemical disposal and handling practices in these industries, that were considered appropriate at the time, are no longer acceptable by today’s environmental standards. Certain chemicals found in groundwater can cause health problems if people are exposed to high enough concentrations over long periods of time.

The majority of the historic reports held by the EPA were completed at a time where soil vapour was not broadly considered however, and after a review of historic files the EPA has determined that it is necessary to undertake further investigations to ensure there is no potential human health risk from vapour intrusion.

The EPA also holds reports it has commissioned (please see ‘Reports’ above).

Are home grown vegetables safe to eat?

Yes, soil vapour contamination generally does not contaminate the soil above it unless it is a source site.

Is bore water safe to use?

Yes, the results from previous stages of work indicated that there is no widespread contamination of groundwater in the Unley assessment area, and no risk to human health from groundwater exposure. Residents who were previously advised not to use their groundwater may now do so. 

Where are Adelaide’s groundwater contamination hotspots?

Site contamination exists in most urbanised areas in the world. South Australia is no exception, particularly suburbs on or near current or former industrial land. As recently as the 1980s, chemicals used by industry were simply tipped down drains and poured onto soil to evaporate.

Groundwater contamination is usually a long-term environmental legacy. Chemicals found in groundwater across metropolitan Adelaide include volatile organic compounds (petroleum hydrocarbons, chlorinated hydrocarbons and other organic compounds), pesticides, polycyclic aromatic hydrocarbons and nitrates.

What is the EPA doing about it?

Once polluted, aquifers can be very difficult to restore. Under the Environment Protection Act 1993, known or suspected groundwater contamination must be reported to the EPA, and it can require the liable party to undertake assessment and if necessary remediation, which means to treat, contain, remove or manage the contamination. In most cases, the original polluter or past/current site owner must undertake or fund this work, including a communication and engagement program to keep affected communities informed.

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. The EPA administers and enforces the Act to ensure responsible parties undertake this work appropriately. It also makes information on contaminated sites available to the public.

What if there is no liable party?

Sometimes identifying the polluter is difficult because it is often the result of previous industrial activity or activities that may have occurred a long time ago. Understanding the timing of the contamination and identifying the polluter is therefore not always possible, and in some cases companies identified as polluters in the past no longer exist.

An ‘orphan’ site is a term used to describe a situation where the original polluter no longer exists, cannot be determined or is unable to carry out or pay the costs of the assessment or remediation that is required. In 2016, the South Australian Government committed to an investment of $7.8 million over four years for the EPA to manage a number of existing contaminated orphan sites. This funding commitment recognises the importance the Government places on dealing with the issue of historical contamination.

How many orphan sites is the EPA currently assessing?

The EPA has undertaken or is currently undertaking works at orphan sites in:

• Albert
• Beverley
• Brighton
• Keswick
• Glenelg East
• Southeastern Edwardstown
• Thebarton
• Unley
• Woodville North.

What about when groundwater causes soil vapour intrusion?

In the rare instance that a home is affected by soil vapour intrusion, the EPA works with responsible parties to assist residents to manage any health risk. When contaminated groundwater enters the indoor air of homes as vapour through cracks in floorboards or concrete slabs, a ventilation system may need to be installed. The EPA uses an indoor air level response range for TCE, which considers long-term exposure levels (24 hours a day, 7 days a week over a lifetime of 70 years) to determine when this is required. 

Ventilation systems have been installed in homes in Adelaide suburbs where levels of TCE have measured above the ‘safe’ categories of the indoor air level response range. The EPA has installed 3 systems in Beverley and 6 systems in Thebarton as part of a pilot trial to test international research and technology to determine whether it could be applied in South Australia.

What if the EPA finds soil vapour intrusion exists in Unley?

The purpose of the work at Unley is to determine whether soil vapour intrusion exists, and if so what further assessment work needs to be undertaken. This work might include sampling on private properties closer to residential buildings, possible soil vapour sampling, indoor air sampling and crawl space or sub-slab sampling. All work on private properties will require the permission of the landowner to do so.

What can be done to neutralise the contamination?

Chlorinated hydrocarbons are incredibly difficult to remediate. They are also very persistent in the environment. There are some technologies that are successful in treating source zones, for example bioremediation, oxidation, thermal, excavation, and pump and treat at the surface. While this can deal with the source zone, it has limited impact on reducing the offsite contaminated groundwater plume size and associated risk.

For further information on health-related queries, please contact SA Health on (08) 8226 7100 or email.

For site contamination related enquiries, please contact the EPA on (08) 8124 4216 or email.