New study helps turn landfills into green areas

By Nikki Sorbello

ABC Wide Bay

Topic:Environment

Kerry Dalton and Nadun Bulathge at the Bundaberg phytocapping trial site. (Supplied: Bundaberg Regional Council)

In short:

Researchers hope new data will help landfill owners move to phytocapping technology, turning dumps into thriving green spaces.

The emerging technology is a method of covering landfill with soil and plants.

What's next?

A national assessment of its use and a three-year research project will update the industry guidelines to help increase the use of phytocapping.

Transforming end-of-life landfills into thriving green spaces could become easier as researchers deliver new data on phytocapping.

Typically, waste dumps are covered with clay or plastic, but phytocapping is a relatively new technology using soil and plants to achieve the same results.

The method has been tested at a Bundaberg landfill since 2019, and Mayor Helen Blackburn said it was the way forward.

"It's certainly a much better way for the environment, but also it does save money in the long term," Cr Blackburn said.

Phytocapping works by using soil and trees to prevent water reaching waste. (Supplied: act.gov.au)

In partnership with Central Queensland University, the council worked with PhD candidate Nadun Bulathge for six months.

From a special scientific device called a lysimeter and moisture sensors, Mr Bulathge was able to analyse seven years' worth of data — roughly a million data points.

"Phytocapping is a nature-based solution, but we don't have numbers," he said.

"We don't have measured figures to prove to regulatory authorities this phytocapping is giving results that are similar to other expensive capping materials."

Mr Bulathge said his research, which was yet to be published in full, would show phytocapping worked better than expected, even under the worst-case scenario.

Nadun Bulathge says he worked with Bundaberg Regional Council for six months to analyse data. (Supplied: CQUniversity)

"My target is to give some kind of practical, industrial-friendly and industry orientated solutions in such a way that the outcome is directly applied to the industry for the betterment of economy," he said.

Range of benefits

The Department of Environment mandates that councils cover landfill sites to prevent leachate, a toxic liquid created when water mixes with the waste, which can contaminate groundwater.

Phytocapping was introduced to Australia in 2003 and first legitimately used in 2011.

It works by trapping water in the soil, so trees can deliver it back into the atmosphere through the transpiration process.

Burrowing bandicoots were discovered on trail cameras at the phytocapping trial in Bundaberg. (Supplied: Bundaberg Regional Council)

Bundaberg Regional Council branch manager of waste and recycling Kerry Dalton said, unlike traditional caps, phytocaps required minimal maintenance, took up excess water and were visually appealing.

The council has already expanded on its initial trial site and is now considering the technology for a second landfill site.

"We are going to start on the next landfill site in the next year, once we have a bit more information to make sure the cap works, that it's effective," she said.

Reclaiming green spaces

Ruby Michael is a senior lecturer in ecological engineering at Griffith University and has been researching phytocaps as long as they've been in Australia.

She said the technology had proven itself equal in engineering performance but had additional benefits other technologies lacked.

"And because the phytocap has such densely planted, diverse vegetation, there's an opportunity for it to really be a flourishing and exciting green space compared to a parkland."

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