Environmental regulations mean that many of Australia’s old-style tips are not up to scratch. Shekar Atla, of the Baw Baw Shire Council, explains the lessons he learnt from rehabilitating the council’s landfill.
Rehabilitating a legacy landfill can be an arduous task for many councils.
Dozens of old Victorian landfills were last year suspected of leaking potentially toxic materials into soil and waterways.
The risk emerged from unlined landfills.
According to the Environment Protection Authority Victoria (EPA), engineered landfill liners of a certain standard were not compulsory until 2004, when a new EPA policy came into effect. Although, the EPA notes, the standards were previously well documented.
EPA Executive Director, Regional Services, Damian Wells says the EPA has been gathering location data from several sources on closed landfills in Victoria.
“While the EPA is unable to provide the number of closed landfills at risk of leaking, we know that site setting and context provide a strong indication of the likelihood based on geology, depth, meteorology, topography, base engineering/ lining (if any), capping quality and maintenance, and leachate and gas management,” Damian says.
“In preparing the location list, EPA is consulting with the metropolitan and regional waste and resource recovery groups who work with local councils and the private sector.”
Damian explains that if a site is not capped and rehabilitated as soon as practicable it may result in large volumes of leachate being generated, risks of contaminating groundwater and local creeks and rivers, migration of landfill gas, stability risks, erosion issues and potential odours – which can be costly to manage.
“These problems can be minimised, controlled or managed if a site is capped and rehabilitated as soon as practicable. Capping material and construction costs, including design consultancy, materials, labour and machinery hire, may also increase over time so it’s preferable to rehabilitate sites as soon as possible,” Damian adds.
“EPA is requiring that landfills undertake progressive rehabilitation work. This means that once a landfill cell is filled with waste, the operator needs to commence rehabilitation work while operating new landfill cells.”
A landfill liner is an impermeable engineered layer of heavy plastic and clay with a gravel layer that protects against groundwater contamination through downward or lateral escape of leachate, and allows for the drainage, collection and extraction of leachate.
The Baw Baw Shire Council, in Victoria’s east, is just one local government forced to grapple with the repercussions of having to rehabilitate an old-style tip.
The Trafalgar landfill was not lined, providing only a hole in the ground where the waste was tipped.
Environmental concerns and the price of transporting leachate from the site led to Baw Baw Shire Council closing its tip in 2011, investing in a $5.4 million rehabilitation of the 4.35 ha site.
Landfill rehabilitation, which involves returning the land to its former state, involves capping and revegetation, the installation and ongoing maintenance of gas and leachate collection systems and decommissioning infrastructure no longer required. Ongoing monitoring and maintenance of the above continues during the long aftercare period.
Shekar Atla, Coordinator Waste and Major Projects at Baw Baw Shire Council, says the council’s landfill commenced operations in the 60s and closed in 2011 – transforming the site into a transfer station.
He says the council experienced challenges managing the leachate and asbestos.
With an insufficient leachate collection system, the team had to transport the leachate to EPA-approved disposal sites.
From 1964 to 2011, the site accepted a range of waste products, such as domestic garbage and commercial waste.
It was an inexpensive landfill option for the council. That was until leachate began over owing the council’s retaining wall and crossing the landfill boundary, posing a risk of contamination to the local waterways.
Since 1964, about 500,000 tonnes of waste is estimated to have been landfilled at the site.
“There were issues leading to the closure and rehabilitation of our landfill which came all of a sudden. As a regional council, we still had three years of landfill life left for kerbside garbage disposal on site,” Shekar says.
Landfill capping, which involves placing a barrier over the lled land ll, includes the option of using compacted clay, geosynthetic clay liners, polyvinyl chloride and high density polyethylene.
To achieve the best results for the environment, the council decided to choose the EPA Victoria’s Best Practice Environmental Management publication (BPEM) cap instead of the EPA’s licence cap design.
“There was huge difference in cost between the existing EPA approved final cap design – less than a million dollars versus the landfill BPEM cap design, which turned out to be more than five million dollars.
“Due to the issues surrounding the leachate and odours leading up to the closure of the landfill in November of 2011, council knew that getting EPA approval for the existing approved final cap design would be an uphill battle. And so, we proactively decided to go with the BPEM landfill guidelines recommended Type 2 design. In coming to this decision, council also considered the on-going costs involved in leachate carting which were huge and also the uncertainty around the long-term issues by not adopting the best practice in the final cap construction.”
He says while it was a difficult decision politically, the result would have long-term benefits for the environment and the budget.
To read more, see page 28 of Issue 12.
Featured image: Murray Cook, Joe Gauci, Mark Koller, Helen Anstis, Shekar Atla, Russell Clarke, Thilina Wanasingha, Levent Hilmi and Phil Cantillon