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Unpicking the unforeseen

Posted 24 Feb

MOD. at UniSA
Mikala Kidd blog

Words by Walter Marsh.

We don’t always know how our way of life could impact the planet in 50 or 100 years’ time. For environmental scientist Mikala Kidd, the problems facing our soil today raises big questions about the future.

“I knew I wanted to do something to do with environmental science – it’s a pretty broad field these days, there’s so many different areas you can get into,” says Mikala, whose love of chemistry was piqued by a winter school elective on soil science.

In the 20th century, the arrival of the motor car changed the way we live and travel around regional Australia. But while the atmospheric impact of the combustion engine is now well-known, the ageing infrastructure of motoring’s golden age also poses ongoing problems for the soil beneath our feet.

Today, Mikala spends her time unpicking the unforeseen long-term side effects of the car and truck on the land they criss-cross.

“Specifically, we do a lot of work with petrol stations — that’s a lot of hydrocarbon contamination,” she explains. “We mostly do remediation and monitoring of any contamination we do find. It’s a process of removing those tanks, clearing out any contaminated soil and if stuff does go into groundwater, looking after that and helping remediate that.

“Luckily people in Adelaide, or the CBD don’t draw on groundwater — most of the issues come from when the hydrocarbons leech into the groundwater through the soil. It becomes more of an issue in regional areas, where people do pull on the groundwater a lot more than they would in metropolitan areas.”

While regional petrol stations are widely distributed, and often some distance from densely populated areas, when something does go wrong the effects can be wide-reaching. The difference between a minor leak and a ecosystem-imperilling disaster comes down to a spectrum of environmental and geological factors, all of which Mikala and her colleagues must take into account when identifying the level of risk and the safest solution.

“If it gets into a creek, that kind of thing, it can cause huge issues environmentally,” she says. “But it does have a lot of dependence on the geology of the site, and the depth of groundwater as well;  if it’s one or two metres, that’s going to be way more of an issue than if it’s 50 metres deep.

“If its a clay, clays don’t leech the hydrocarbons very easily because its a very tightly-packed medium. When you have sand, that’s a huge issue because it’ll just leech straight through — it can travel a really long distance in a very short time. All those factors create a profile of what needs to be done on a site.”

For the most part, Mikala’s work involves cleaning up the long tail of infrastructure installed at a time when ‘best practice’ — and the technical knowledge, regulatory standards and priorities that informed it — looked quite different.

“Most of the issues that we deal with are with tanks from the 1960s and 70s leaking,” she says. “Nowadays they have way better technologies with the tanks they installed – they’re double-lined, with a vacuum seal in between so you can detect any pressure changes if there’s a leak. Whereas in the 1950s, 60s 70s =, they’d just put metal tanks in which could rust — no one really knew any better.”

Beyond petroleum, contaminants ranging from fire retardant PFAS to dry cleaning fluids imperil ecosystems and humanity in unexpected ways. “PFAS is a really big issue because it moves a lot easier within water and within soil, it can move way greater distances in less time,” she says.

“What we deal with nowadays was once super normal — even up until the 90s PFAS was used pretty heavily. [Often] it’s just something they did in the past, and didn’t really know any better. Now it’s up to us to fix that.”

As Mikala and her colleagues clean up the unforeseen ways past practices conflict with our present needs, their work touches on broader questions about humanity’s evolving use of land, and our responsibilities not only to those currently living on it, but far into the future. This reaches far beyond rusted out petrol stations on the side of rural highways, from suburban infill causing once industrial areas to be transformed into residential areas to attempts to ‘future-proof’ nuclear waste disposal sites for thousands of years.

“Now there’s a lot of research being done with any new emerging materials to make sure they’re not going to be really mobile in the environment if they do happen to get out in 50 years time,” she says — to ensure we’re making things safe now.”

“Land is just such a precious resource that is also non-renewable, so we really need to take care of it. And where we can, remediate it to the best of our ability — because we’re not gaining any more of it.”

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