Point cook thermal desorption remediation project

Full: Introduction - Enviropacific were engaged by the Commonwealth of Australia (Department of Defence) to undertake the source removal remediation of a former fire training area (FTA) located at the RAAF Williams Base, Point Cook, Victoria (the Site). Historical fire fighting training activities, in particular, were suspected to have tainted the underlying soil and groundwater. With confirmed evidence of contaminated soil and groundwater, a remediation plan (AECOM, 2010) was developed to address the organic hydrocarbon contamination including DNAPL, LNAPL and dissolved phase contamination. During 2014 approximately 70,000 tonnes of highly contaminated soil were treated by ex-situ direct fired thermal desorption technology. Method - In mid-2013 Enviropacific commissioned the manufacture of a direct-fired thermal desorption (DTD) plant for the purpose of treating contaminated soil at the Site. The DTD plant was mobilised to site from the US in late 2013, with installation and commissioning of the plant being completed in early-2014. Proof of Performance (PoP) testing at a feed rate of 23 tonnes per hour was completed successfully in early April 2014 and full scale treatment operations commenced shortly after. Following further optimisation works the DTD operated at up to 30 tonnes per hour and an additional three PoP tests were completed. Treatment activities ceased in February 2015 and the Site has been rehabilitated and revegetated. Key challenges have included: Design and construction of a DTD plant capable of effectively treating high concentrations of chlorinated hydrocarbons; Design and construction of general site facilities including water treatment plant, emission control systems, major services including 2 km of underground HV power and water; Development of a strong multidisciplinary team capable of managing the project complexity and delivering successful environmental outcomes; Commissioning and operation of the DTD plant under an active flight path and close to Port Philip Bay with gale force winds; Health and safety considerations when working around highly odourous and volatile hydrocarbons; PFOS co-contamination. Results and discussion - This paper will discuss the challenges faced and results achieved in this complex thermal remediation project. (author)