Chemical Fixation of Contaminated Soil from Gasworks Site


Chemical Fixation of Contaminated Soil from Gasworks Site

David Alden and Gary Birk (Tersus Environmental, LLC)
Richard Stewart (Ziltek)


David Alden

Tersus Environmental, LLC

Speaker Bio:

David Alden is a Technical Associate with Tersus Environmental where he provides technical support for Tersus’ portfolio of biotechnology-based solutions to manage complex, challenging environmental liabilities and reduce costs for site closure. He is a graduate of Universidad de las Americas-Puebla, Mexico, where he majored in Civil Engineering with a focus on waste-water treatment and and holds registration as a Professional Engineer in North Carolina. Alden worked for 4 years in the upstream oilfield sector performing offshore well tests and completion design and installation in the Gulf of Mexico. He participated in the in-situ oil-shale extraction experiment in the Piceance Basin, in Northwestern Colorado where protecting groundwater was the main challenge. Alden recently specialized in groundwater studies, completing a Masters Degree program in Joseph Fourier University, Grenoble France


A former gas works site located at Mead St, Birkenhead in South Australia, contained around 2,000 tonnes of PAH-contaminated soils that required off-site treatment and disposal. A combination of activated carbon, clay and aluminum hydroxide was used to immobilize the PAH contaminants to allow for safe disposal. McMahon Services provided supplied specialist soil mixing equipment and the treatment was conducted at a purpose-built treatment shed located at the Integrated Waste Services landfill site in Dublin, South Australia. The treatment process involved adding chemical fixation products and a solidification agent at 5% by weight. A single pass reduced the leachability of the PAHs and BaP to below the landfill criteria for Low level Contaminated Waste (LLCW) to allow the safe disposal of the treated soil. In addition, the treated soil passed the Multiple Extraction Procedure (MEP) which is recognized as one of the world’s most stringent soil leachability test. Overall, the project took out a prestigious National prize at the Civil Contractors Federation (CCF) Earth Awards in 2011. The award recognized companies Ziltek and project partners McMahon Services and Integrated Waste Services for expert management of high-level contaminated soils.


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