Melbourne Water has fixed and filled a collapsed Springvale South landfill site using clay-rich biosolids.
Melbourne Water’s General Manager Integrated Planning, Chris Williams, said about 1.3 million tonnes of treated biosolids stockpiled at the Eastern Treatment Plant (ETP) were reused to finish the project.
“For the past decade Melbourne Water has been investigating other ways to use these biosolids. This landfill project was a perfect opportunity to do just that. We found this material can also be used in construction and roadworks or to produce bricks,” Mr Williams said.
“Some of the product has also been used in our own projects at the ETP, cheaply and effectively.”
Biosolids are the solid materials generated in the wastewater treatment process, separated from the liquid before being treated and dried.
The drying pans at the ETP were originally lined with clay, which meant that every summer when the pans were harvested, an amount of clay was scrapped and mixed with the biosolids.
Over the past few years, Melbourne Water has added a protective layer of cement-treated crushed concrete to the drying pans – allowing for harvested biosolids to be used more broadly, such as for agricultural purposes.
The landfill rehabilitation project was carried out by Progress Earth, an earthworks contracting business.
Progress Earth Director, Craig Carter, said he was delighted to collaborate with Melbourne Water to deliver a suitable reuse solution for the biosolids within the guidelines of the Environmental Protection Authority (EPA).
“Considering it hadn’t been done before on this scale it was very pleasing to get the approvals in place and into the project. I think it has been a fantastic outcome for both Melbourne Water and the Clarke Road Landfill,” Mr Carter said.
Under EPA guidelines, biosolids need to be stockpiled for three years to ensure they are bacterially safe and around 30,000 tonnes are produced annually at the ETP.