Legislative Council

QUESTION: Oaklands Estate groundwater contamination

February 28th, 2017

On the 28th of February 2017, Mark asked the Minister for Sustainability, Environment and Conservation a question about groundwater contamination near the Oaklands Estate.

The Hon. M.C. PARNELL: Just before Christmas Renewal SA wrote to residents of Mitchell Park and Clovelly Park advising them that the spread of the plume of contaminated groundwater is much worse than first thought. The agency also reiterated its advice to the community not to use bore water for any purpose. Also worrying is the indication that the contaminated plume could soon impact on the Oaklands Estate. Also at risk is the Oaklands Wetland, which is located adjacent to the Warradale Army Barracks and across the road from the Marion outdoor swimming centre.

The wetland is home to a diversity of wildlife, including birds, aquatic life and protected species; however, the key purpose of the wetland itself is to clean and supply water to parks and gardens in the Marion Council area. It is described by council as a 'water farm'. My questions to the minister are:

1. What arrangements are in place to protect the Oaklands Wetland from the contaminated plume, which is now just two or three blocks away?

2. What impact will groundwater contamination at Oaklands Estate have on the aquifer storage and recovery program at the wetlands?

The Hon. I.K. HUNTER  (Minister for Sustainability, Environment and Conservation, Minister for Water and the River Murray, Minister for Climate Change): I thank the honourable member for his most important question and his ongoing interest in this subject. In terms of the greater extent of the plume and its movement, I think it is moving in a couple of directions, south-west and north-west, but generally west, as you would expect groundwater to move in that part of Adelaide. Indeed, across the floodplain that was Adelaide, the normal groundwater movement is in a westerly direction. Sometimes, for local-specific reasons such as former creek beds being covered up by glaciation events and other inundations which have deposited levels of topsoil over the eons, you get localised movement in different directions, occasionally. However, normally it would then resume its westerly direction towards the gulf.

We are talking about groundwater contamination of TCE in this situation, and remember, from our discussions about this substance in previous years, it has essentially been a contamination of the topsoil, which has soaked down into the groundwater in many cases, mainly around institutions that used TCE for industrial purposes: car crash repair shops, car production in many guises, dry cleaners as well, and indeed I think I have reflected in this place that in my younger years, as a laboratory assistant, I used to use it to dissolve the wax out of my pathology slides and I would be dipping my hands into this material at the same time.

The other thing to remember about this substance is that it is incredibly volatile. When it comes into contact with the air, it essentially evaporates. Of course, it is also incredibly diluted when it comes into contact with groundwater. So, the concern in terms of this substance of TCE in groundwater is largely limited to two instances: one is when that groundwater is utilised through bores for drinking water purposes, and that's why there are advisories out to residents generally right across Adelaide, where there may have been industrial uses of this chemical in the past, not to use bore waters, particularly not to use them in any situation for drinking water supplies in metropolitan Adelaide.

The other issue of concern, as we saw in previous times, was in terms of vapour intrusion up through the soil and into the crawl spaces under houses. Again, that was very dependent upon the construction of the house, whether in fact it was a concrete slab on ground or whether it had a protective plastic membrane under that concrete slab; or if there were an elevated crawl way or walkway underneath that allowed the appropriate ventilation under floor. The contamination issues were really limited to those houses certainly in the Mitchell Park/Clovelly Park areas which had concrete slab on ground, with no protective membrane. I can vaguely recall that the concern production period for those sorts of houses was in the mid 1980s through to the mid 1990s. Subsequent to that, regulations were brought into place to provide for protective membranes under those concrete slabs, which prevented these problems.

To come to the gist of the honourable member's question: is there going to be any concern with the contact of the groundwater into the wetlands, I have no advice to that question, about whether there will be concerns or whether in fact there will be any connection between the groundwater and the wetlands. I am not sure that that's the case. I will have to take that on notice and bring back a response.

In any event, if there were, and again I will get some certain scientific advice from my agency about this, my expectation would be the further dilution of the chemical and the opportunity for evaporation will see that that chemical has absolutely no impact on the water. That would be my expectation but, again, I must hesitate to advise the council that I have no formal scientific training in that area, other than having used this chemical myself in the past in a laboratory. I will seek a response from my agency for the honourable member and for any community members who might be concerned. My expectation is that any contact of this chemical from groundwater into any surface environment would lead to a very rapid evaporation and therefore be of no concern. But I will follow up and get an answer for the honourable member.

 On the 30th of May 2017, the following reply was provided -

Hon I Hunter MLC:

“I have sought the advice of the Environmental Protection Authority (EPA) and have been advised that:

The Oaklands Wetland Managed Aquifer Recharge (MAR) scheme harvests water from the Sturt River which is then treated in the wetland and pumped to the tertiary aquifer, which is almost 100 metres below ground.

Contaminated groundwater is confined to the separate, upper aquifer of less than 25 metres below ground. Results of the groundwater investigations to date do not indicate that the water or aquifer used as part of the MAR scheme is being impacted by the offsite groundwater contamination.

The independent site contamination auditor engaged by Renewal SA, as the site owner of the former Mitsubishi Motors site, is still finalising assessments however the interim audit advice provided to the EPA indicates that neither the Sturt River nor the Wetlands have been impacted by groundwater contamination.”

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