Halifax Convention Centre, 1650 Argyle Street, Halifax, NSJune 4-5, 2019
Background/Objectives. Historical use of aqueous film-forming foam (AFFF) at Royal Australian Air Force (RAAF) Base Williamtown in Australia has resulted in per- and polyfluoroalkyl substances (PFAS) contamination of groundwater and stormwater, both of which migrate off Base. Following the successful installation and operation of a stormwater treatment system at the Base, Defence requested a system to treat a groundwater source beneath the former Fire Training Area at the base. Prior to the contamination being identified, the aquifer was historically used for drinking water. Residents continue to use the aquifer for non-drinking domestic purposes. The affected aquifer lies within four metres of the ground surface and the water table increases substantially during rainfall. Approach/Activities. Defence requested the supply and operation of a 12.5L/sec treatment system to remove PFAS from the source beneath the former Fire Training Area. 15 extraction wells were installed and the provider worked closely with the environmental consultant to determine the best use of the extraction wells to meet project objectives. The custom supervisory control and data acquisition (SCADA) system provides real time data to allow educated well management decisions to be made to optimize PFAS mass removal and manage plume migration. The treatment system operates at or near its design capacity of 12.5 L/sec. The various components are installed inside three international shipping containers. The process flow includes sand filtration for iron and solids removal, two stages of pre-treatment resin to remove the total organic carbon (TOC) and colloidal iron, lead and lag regenerable resin vessels for PFAS removal, and polish resin to enhance the removal of short-chain PFAs compounds. The regeneration system facilitates the delivery and recovery of the proprietary regeneration solution, including distillation and superloading components to maximize reuse of the regenerant solution and minimize waste generation. The treated water is subsequently dispersed via an extensive sprinkler array, which is monitored to ensure pooling of water on the surface does not occur, particularly during times of high rainfall. Results/Lessons Learned. The groundwater treatment system has been operational since commissioning in July 2018 and has treated more than 104 million litres of water to below the Australian Health Based Guidance Values 0.07 µg/l for PFOS+PFHxS and 0.56 µg/l for PFOA. The high rainfall in the region and resulting increases in the groundwater table, sometimes for weeks on end, can impact upon the capacity to disperse the treated water without impacting the operational capability of the base. Close collaboration with the environmental consultant and Defence has allowed ongoing operations with limited downtime. The utility of the SCADA system, combined with the regenerable resin technology, results in consistent attainment of sustainable remediation objectives and minimizes waste generation. Marilyn Sinnett, Lead Mechanical Engineer, Emerging Compounds Treatment Technologies Marilyn Sinnett is the Lead Mechanical Engineer at Emerging Compounds Treatment Technologies (ECT). ECT is an equipment company focused on developing and commercializing treatment technologies for emerging, difficult-to-treat contaminants.
Following an exceptional weather event that occurred in July 2016, approximately 900 litres of aqueous film-forming foam (AFFF) (Ansulite 6%) was spilled at Canadian Forces Base Bagotville, in Saguenay. The storm water and foam migrated to the storm sewer network and into a retention pond with a holding capacity of 4,500 m3. As a result of the strong rains, the retention pond reached its full capacity and part of the water held there was pumped into four reservoirs with a total capacity of 320 m3 (four reservoirs of 80 m3). A carbon water-treatment unit was mobilized to the site to begin treating the water in the retention pond. The choice of filtering media was made based on previous treatment trials conducted by the Department of National Defence (DND). The temporary discharge criteria taken from the Federal Contaminated Sites Action Plan (FCSAP) - Provisional Guidance to Federal Departments for the Management of Contaminated Sites was 6 µg/L for perfluorooctane sulfonate (PFOS) and for this reason, a closed-loop water treatment strategy was used. Closed-loop water treatment operations made it possible to achieve the City of Saguenay’s discharge standards as well as those set for PFOS. The water volume treated by the closed-loop system in the retention pond and the four reservoirs was 7,200 m³ and 4,800 m³ respectively. The water treated in the retention pond and reservoirs was discharged into the storm sewer network on-site or into the municipal sewer network after approval from the City of Saguenay. There were several challenges with this project: 1) Validation of the proper filtering materials for the treatment of water containing an emergent contaminant within the context of an environmental emergency where time is ticking; 2) Minimum analysis timeframes of 72 hours following the receipt of samples at the laboratory; 3) Unfavourable weather conditions (heavy rains) with a retention pond and reservoirs having reached their full capacity and 4) Determination of the discharge criteria since only a single parameter of the per- and polyfluoroalkyl substances (PFAS) is standardized for a discharge into the environment. Marie-Noelle Riverin, Hydrogeology Engineer, Golder Marie-Noëlle Riverin earned a bachelor’s degree in Geological Engineering from Université Laval de Québec in 2003 and a master’s degree in Earth Sciences (Hydrogeology) from the Institut national de la recherche scientifique - Centre Eau, Terre et Environnement de Québec in 2006. She joined Golder in 2008 and is now an intermediate professional as a Hydrogeology Engineer. These projects enabled her to gain solid technical expertise in environmental characterizations (Phases II and III), remediation of contaminated sites (Phase IV) as well as hydrogeological modelling. Ms. Riverin was also involved in numerous hydrogeological studies with the purpose of developing and implementing groundwater quality monitoring programs. She also has field experience in mining exploration and environmental site characterizations and is capable of completing environmental follow-ups at various sites.