City of Melbourne Greenline project

GPT’s sustainability innovations delivery manager, Dale O’Toole, says getting your head around water neutrality is not easy.

“Usually, when I mention that, the first question I get is – what do you mean by water neutrality?”

There’s even international debate about what that actually means, he says.

“Water neutrality is much more than just water consumption. It considers the pollutive elements of stormwater and the velocity impacts of stormwater.”

According to O’Toole, a company committed to being “water neutral” should eliminate the environmental impacts of “the water cycle”, and if that can’t be done, then the company should reduce those impacts or compensate for its effects on nature.

“I can’t say GPT has locked this in, but I can tell you that Steve (Ford, head of sustainability and energy) and I are very committed to pushing this through – and the impact of stormwater is much more of a major issue than people would realise.”

O’Toole argues that in the same way that the industry wants to reduce carbon, it should also want to reduce how much water is used in their assets – especially the pollutants it may contain.

“It’s so innocuous – people wash their car, and it goes down there, and you look at our shopping centres, and you have water running off car parks, but when you start to dig into the research behind it, it is horrendous, some of the pollutants that are coming off car parks and other areas.”

“The smaller, dissolved pollutants are the biggest problems”. They have a myriad of sources – from the chemicals embedded in tyres that come loose on bitumen to cleaning chemicals.

At shopping centres, for instance, when water hits an open car park, it picks up all the pollutants and ultimately goes to a waterway – some are very sensitive.

“Everyone understands water efficiency,” he says – but not so much the quality of the water allowed to go off site and ends up in streams and rivers.”

O’Toole wants to create clear pathways to better outcomes, so he’s co-opted former GPT sustainability manager Bruce Precious to solve some of the problems and plug some of the knowledge gaps in the industry.

“We set up a fledgeling industry group to get many more people to engage on this,” O’Toole says, adding that there have been initial discussions with Melbourne Water, Greater Western Water, and GreenFleet.

O’Toole’s plans are still in the making, so he’s not revealing details yet.

And there is so much to do, much of it potentially sensitive.

For instance, changing the location of the water discharged from office towers.

In Sydney, for instance, office towers often discharge to a main trunk pipe in the centre of Sydney, “which goes out to the Sydney Harbour – which is not great in any respect, but it’s a different thing than going to a local creek,” which some actually do, he adds.

“A local creek has less resilience than a big outlet going into the Sydney Harbour, so a big part of work we are doing with Melbourne Water defines the degree of sensitivity of those receiving bodies of water.”

Treating Stormwater

It’s a major problem when there are storms.

When there’s torrential rain, he says, “pollutants smash into the riverbank and erode the bank, and that releases a lot of sediments, and the sediment itself causes so many problems for silt that it smothers the aquatic life underneath it.”

Animals bear the brunt of damage, and insects in food chains get washed away, affecting local aquatic life.

Permeable concrete

One solution is permeable paving.

“We are exploring the ability to do that in our car parks and logistics assets, but we also want to push this harder in our retail purchases,” O’Toole says.

But of course, it’s not so simple, O’Toole says.

“It has to be done correctly. If you don’t do it correctly and you have a clay surface underneath – clay just doesn’t hold water, so you’ll need to find a subsoil that will accommodate this, but if you don’t, there are other ways to channel the water away.

“We’ve had some discussions with local councils, and they are very anxious about heat island impact, and if this was a traditional hard surface on a 40-degree day in Melbourne, it would go straight to the creek, and the temperature of the water that hits the local stream is damaging to aquatic life.”

Other filtration methods

According to O’Toole, businesses could also look at stormwater detention, where an underground tank is used to capture and slow down the velocity of the water before it goes out to local waterways.

“It can break down velocity impact, but you can also look at putting a gross pollutant trap or mechanical cleaners to ensure the water is relatively clean before discharging it, and we have already had a number of those on site.

“There are all types of treatment systems, you’ve got filter baskets, and there are maintenance regimes to check these periodically because they won’t do much good if they block up.”

“Shopping centres spray weed killer to stop all weeds in footpaths or herbicides in our landscapes, insecticides on our loading docks, but all these terrible chemicals get washed down with rain and go into the waterways.”

One solution is to choose a less harmful herbicide.

“An example of something we’ve been working on is conducting water samples to better understand what goes into the waters.

“I came from a public health background, and I used to be involved in the outbreak of the Legionnaires’ disease, and when I went into the built environment, it was more about saving water, and I get that, but from what I’ve learned in the past nine months – I’m fearful of what’s taking place in terms of stormwater.

“Now that we can’t stop people from driving cars, things like rain gardens could actively filter out much of this stuff.”

-with Bevin Liu

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