A pilot-scale trial, believed to be the first trial of it’s kind in the world, will be conducted for an Australian government client. Aqueous film-forming foam (AFFF) firefighting foams were used at this location from the 1970’s until the start of a phase out period initiated in 2004. In 2016 an environmental assessment conducted at the client’s site identified areas impacted with per- and polyfluoroalkyl substances (PFAS) from the historical use of the AFFF foams. Based on these investigations, 2,500 tonnes of soil identified with PFAS impacts have been selected and designated for the physical/chemical treatment system pilot-scale trial.

The presentation will summarize the results of the pilot-scale testing on the PFAS impacted soils. An outline of the physical/chemical integreated soil and water treatment process will be provide along with a summary of the results of the testing focusing on soil type, starting PFAS concentrations and results achieved. Results will be compared to the remedial objectives established for the site presented as total and leachable PFAS and mass removal measured by the total oxidizable precursor (TOP) assay and the total organic fluorine (TOF) analysis.

Colin Morrell, Senior Vice President, Research and Development, CleanEarth Technologies
Colin Morrell is the Senior Vice President of Research and Development at CleanEarth Technologies with experience in the assessment and remediation of contaminated sites. Colin leads CleanEarth’s PFAS team, which is focused on development and delivery of PFAS remediation solutions. Development of solutions is being driven through a range of mechanisms including agreements with vendors, internal and external research, laboratory trials and university partnerships primarily in the areas of enhanced soil washing.

Per- and polyfluoroalkyl substances (PFAS) have been identified by many regulatory agencies of being compounds of concern within the environment. In recent years regulatory authorities have established a number of health-based regulatory values and evaluation criteria with values for groundwater typically being less than 50 nanograms per litre (ng/L). Subsurface studies suggest that the compounds are widespread in the environment and are recalcitrant. Traditionally, impacted groundwater is extracted and treated on surface using media such as activated carbon and exchange resins. These treatment technologies are generally expensive and not efficient and can last for decades. The application of in-situ remedial technologies is common for a wide variety of compounds of concern however the application of in-situ technologies for PFAS is just emerging. This study involved the application of colloidal activated carbon at a site in Canada. The PFAS compounds perfluorooctanoate (PFOA) and perfluorooctane sulfonic acid (PFOS) were detected in the groundwater at concentrations of up to 3,300 ng/L and 1,500 ng/L, respectively prior to remediation. The shallow silty sand aquifer was anaerobic in nature with a groundwater flow velocity of approximately 300 m/year. The colloidal activated carbon was applied using direct push technology resulting in the removal of the PFOA and PFOS to concentrations at and below the analytical detection limit (> 20 ng/L) over a 26-month period. Analysis of other PFAS post-injection showed that all of the PFAS analyzed were below their respective method detection limits. Detailed examination of cores taken post-injection indicated that the colloidal activated carbon was successfully distributed within the target zone of the impacted aquifer with the activated carbon being measured up to 5 m away from the injection point. The results of the study suggested that colloidal activated carbon could be successfully applied to address low to moderate concentrations of PFAS within a shallow anaerobic aquifer.

Rick McGregor, President, InSitu Remediation Services Ltd.
Rick McGregor is the President of InSitu Remediation Services Ltd. and has over 26 years’ experience in groundwater and soil assessment and remediation. Rick has worked in over 30 countries and has authored numerous papers on groundwater assessment and remediation. Rick holds a M.Sc. from the University of Waterloo in hydrogeology and geochemistry and is a Certified Ground Water Professional in Canada and the United States. He recently published the first paper on the in-situ remediation of PFAS in groundwater at a site in Central Canada.

We have demonstrated that ball milling can destroy per- and polyfluoroalkyl substances (PFAS) in contaminated soil. PFAS impacted soil from a 50+ year old firefighting training area (FFTA), as well as PFAS-spiked, silica-based sand, were used in all trials. Three different sized ball mills were used to evaluate and demonstrate scalability. A suite of 13 PFAS compounds spanning and extending beyond those with Canadian guidance values were tracked in all cases. Our results demonstrate up to 97% of the PFAS is destroyed within minutes in two types of soil, sand and clay, and that no identifiable PFAS products are produced. Conventional remediation technologies are not effective for the destruction of PFAS; this methodology of onsite PFAS-contaminated soil remediation is cost-effective and will be scaled on-site to develop detailed operational requirements.

Nick Battye, Geoscientist, Environmental Sciences Group, Royal Military College of Canada
Nick Battye is a geoscientist with the Environmental Sciences Group (ESG), located at the Royal Military College of Canada in Kingston, Ontario. The Environmental Sciences Group is a cost-recovery, multidisciplinary team uniquely located within an accredited university that is part of the Canadian federal government. On behalf of various federal governments and agencies, the group has conducted fundamental research and applied projects at over 150 locations across Canada on a wide variety of environmental issues and technologies, with an emphasis on contaminated sites, emerging contaminants, and remote locations.