Unlike many federal contaminated sites where source materials originate from geographically-fixed infrastructure (e.g., underground fuel storage tanks) or activities (e.g., dump sites), it is expected that release of per- and polyfluoroalkyl substances (PFAS)-containing source materials at federal facilities will have occurred in numerous areas which are challenging to spatially and temporally define due to the nature of historical operations (e.g., firefighting equipment maintenance/testing) and historical release events (e.g., fuel-based fires, aircraft crash sites). Environmental site assessments completed at one Canadian military base identified more than 20 areas of potential environmental concern (APECs) occurring over an area of 450 hectares, with PFAS as the primary potential contaminant of concern.

The irregular release of PFAS at this particular federal property, combined with the mobility and persistence of these chemicals in the ambient environment, has contributed to the detection of PFAS in surface water, groundwater and soil throughout the base. As such, a new approach for classifying the contamination under the National Classification System for Contaminated Sites is being sought given the unique history of use and physico-chemical properties of these substances, as well as the need to adopt a contaminant-specific approach to effectively manage potential risks to human health and the environment.

This presentation will review the activities conducted in support of this novel approach for site classification (e.g., contaminant-specific Phase I environmental site assessment, base-wide stormwater monitoring and sampling) and will detail how this approach generates a more accurate representation of contaminant migration, potential for exposure to human and ecological receptors and priority for further action.

Erica Milligan, Senior Scientist, SLR Consulting (Canada) Ltd.
Erica Milligan is a Senior Scientist at SLR Consulting (Canada) Ltd.

Public Services Procurement Canada (PSPC), on behalf of the Department of National Defence (DND), has carried out environmental investigations in the firefighting training area (FFTA) at Canadian Forces Base (CFB) Comox since 2002. The FFTA has been used for fight fighting training purposes since at least 1968 and includes a gas hut and a water retention pond. A network of tributaries connect to the Scales Creek which, combined with other creeks, discharges into the Straight of Georgia further northwest of the CFB Comox property. An inventory of Species at Risk (SAR) carried out for CFB Comox in 2012 confirmed the presence of 14 SAR. The presence of northern red-legged frogs and breeding sites were identified in the retention pond at the FFTA and in nearby Scales Creek. A water resource desktop study conducted in 2016 identified groundwater and surface water extraction points offsite with potential for potable water and/or domestic use and agricultural purposes. The regulatory framework used for the environmental investigations in 2018 include: Health Canada’s Drinking Water Screening Values (DWSV); Canadian Council of Ministers of the Environment (CCME) draft Canadian Water Quality Guideline for perfluorooctane sulfonate (PFOS); Health Canada Soil Screening Values for Agricultural/Residential/Parkland land use; and, Federal Environmental Quality Guidelines (FEQG) for Agricultural and Residential use. The BC Ministry of Environment (BC MoE) has introduced remedial standards for soil and groundwater which would also apply for offsite properties.

Results from the environmental investigations conducted in 2002 identified contamination in the subsurface by hydrocarbons from the use of fuel oil and storage of waste oil. Subsurface investigations have been conducted at the FFTA area for select per- and polyfluoroalkyl substances (PFAS) since 2015 from the fire fighting foams used and fire fighting agents deposited historically, in addition to hydrocarbons, volatile organic compounds (VOCs) and metals. PFAS were detected in soil, groundwater, sediment and surface water and exceeding the regulatory criteria considered as currently applicable for remediation. The stratigraphy, surface water flow and groundwater flow at the FFTA area and CFB Comox site is complex. A conceptual site model was created in 2018 based on the data collected during the environmental investigations for characterization of the plume and evaluation of contaminant transport. While the understanding of the PFAS contamination characterization, fate and transport mechanisms have been improving in the recent years, remedial technologies for soil and water to treat PFAS contamination have also been evolving. The level of success from the use of the existing technologies and approach for risk mitigation and remediation of PFAS contamination is currently uncertain.

This presentation will be focused specifically on the PFAS contamination at the FFTA of CFB Comox, evaluation of risk management approaches and risk mitigation technologies to help PSPC and DND achieve their objectives for environmental due diligence and compliance for both onsite and offsite receptors.

Dave Osguthorpe, Environmental Specialist, Public Service and Procurement Canada
Dave Osguthorpe is an Environmental Specialist with Public Service and Procurement Canada (PSPC), in Victoria, British Columbia. Dave holds a Bachelor of Science degree in Environmental Science from Royal Roads University, a Diploma of Environmental Technology from Camosun College, and is certified by ECO Canada as an Environmental Professional (EP). Dave has worked with the PSPC Environmental Services, Contaminated Sites team for seven years, and is currently the PSPC Program Manager for CFB Comox.

Vijay, Senior Engineer, Arcadis Canada Inc.
Mr. Vijay Kallur is a Senior Engineer with Arcadis Canada Inc., and manages multiple roles in the Pacific Region for; Client Development, Client Program Management, Technical and Business Management.  He holds a graduate degree in geotechnical and environmental engineering from the University of Saskatchewan, with over 29 years of multi-disciplinary experience in environmental, civil, geotechnical and construction management.  He is one of the senior members of the Contaminated Sites Approved Professionals Society in British Columbia.  Mr. Kallur has worked in various sectors assisting clients as an advisor for regulatory compliance and providing expertise and leadership in strategic environmental risk management for large environmental programs, spill response, infrastructure and development, industrial and high risk sites.

In December 2005 the largest explosion in Western Europe since World War Two occurred at the Buncefield Oil Storage Terminal in the UK. In controlling the resulting fires approximately 250,000 litres of firefighting foam containing perfluorooctane sulfonate (PFOS) were deployed, a proportion of which directly impacted the underlying chalk Principal Aquifer which lies within a protected drinking water abstraction zone. Investigations identified PFOS to be present in groundwater beneath the site resting at approximately 35m below ground level, with source concentrations of PFOS ranged from between 20 to 50µg/l, well above the 0.3 µg/l guidance values in the UK.

We evaluated the transport of PFOS in fractured bedrock groundwater towards the drinking water abstraction. In this case, PFOS was discharged concurrently with the fuels and provided an opportunity to characterize the transport of both PFOS and hydrocarbons including benzene, toluene, ethylbenzene, xylenes (collectively, BTEX), and the fuel oxygenate methyl tertiary butyl ether (MTBE). The transport properties of BTEX and MTBE are well known. Therefore, comparing the transport of these hydrocarbons with transport of PFOS at this well-characterized site after a known discharge event has afforded a unique opportunity to gain insight into the transport of PFOS in the environment.

Site investigation activities included the completion of soil boring and bedrock boreholes, downhole geophysical investigations and the installation and sampling of groundwater monitoring wells for concentrations of PFOS, BTEX, and MTBE. Routine sampling of monitoring wells has ensued on a near-monthly basis for a period of up to five to seven years, thereby providing a detailed record of environmental monitoring. Contaminant modelling has also been undertaken during the quantitative risk assessment process along with remediation activities including groundwater pumping and capping of 12,000m3 of shallow soils impacted with PFOS both designed to remedy the potential impacts of the original incident.

The project has resulted in significant insights being gained regarding transport of PFOS in fractured rock at the site, including characterization of background PFOS concentrations and attenuation mechanisms such as retardation and dual-porosity mass transfer characteristics. Giving the significant increase in recognition of the number of potential per- and polyfluoroalkyl substances (PFAS) source zones globally and the significant number of drinking water supplies at risk these insights will be of interest to a wide audience.

John Vogan, Corporate Development Director, Arcadis
John Vogan is a hydrogeologist with more than 25 years’ experience in groundwater and soil investigation and remediation. John is responsible for supporting Arcadis technical project execution throughout Canada, and is a member of the Arcadis global emerging contaminants working group. Prior to joining Arcadis, John led a pioneering in-situ remediation company, originally a ‘spin-off’ of the University of Waterloo, which established passive permeable reactive barrier (PRB) groundwater treatment technology in the marketplace. John has co-authored over 30 technical publications and taught several short courses in collaboration with the United States Environmental Protection Agency (USEPA).

Since the late 2000s, 14 Wing Greenwood (Nova Scotia) has been a vanguard of per- and polyfluoroalkyl substances (PFAS) understanding, assessment, and strategic management. As one of the first bases in Canada to investigate PFAS impacts in the environment, work completed to date at the base has set much of the foundation for how PFAS are assessed and managed across the country (including the development of an industry accepted PFAS Sampling Guidance Protocol and, in consultation with Defence Construction Canada, Department of National Defence, and Environment Canada, completion of the first National Classification System for Contaminated Sites (NCSCS) Scoring for a PFAS impacted site).

Based on work conducted at various sites across the base (including the former firefighting training area, aqueous film-forming foam (AFFF) lagoon, hangars, taxiways, explosive ordnance disposal (EOD) range, and other historical sources of PFAS/AFFF application) pursuant to Steps 2 through 6 of Federal Approach to Contaminated Sites, this case study will focus on key findings related to PFAS assessment (and fate and transport) during the past decade that speak to fundamental gaps relative to our industry’s current understanding of PFAS science. Specifically, this case study will discuss how PFAS impacts were strategically addressed when the base’s main water supply well was first identified as having PFAS contamination despite limited and unenforceable regulatory guidance; correlate long-term surface water and sediment monitoring results collected along a brook that runs through the base, near many of the PFAS impacted sites; discuss the QA/QC implications (i.e., cross-contamination) of using materials “prohibited” by PFAS sampling protocol (e.g., double-check valve bailers, jute twine, rain gear, water totes, and low-density polyethylene (LDPE) tubing); present the application and evaluation of the total oxidizable precursor (TOP) Assay and precursor data; evaluation of weathered rock relative to PFAS concentrations in groundwater; and fate and transport in a complex dynamic hydrogeological setting.

Andrew Thalheimer, Partner, Dillon Consulting Limited
Andrew Thalheimer, P.Eng., is a Partner with Dillon Consulting Limited and is based in Halifax, NS. As Dillon’s National Remediation Leader, Andrew is a senior technical specialist with over 30 years of experience in contaminated site assessment and remediation. Andrew leads Dillon’s emerging contaminant program advancing the state of the practice in PFAS assessment and risk management and raising the awareness of PFAS within industry and regulatory communities. Over the last decade, he has worked as a technical expert on numerous sites that have involved PFAS characterization and assessment, presented PFAS-related topics at countless conferences across North America, co-presented a one-day training course on PFAS fundamentals, was a contributing expert in the update of Transport Canada’s PFAS Field Sampling Procedures, and was a contributing author to the National Ground Water Association’s (NGWA) “Groundwater and PFAS: State of Knowledge and Practice” guidance document. In addition, Andrew was the Principal Investigator for research conducted for the North American airport industry on managing AFFF and identifying areas of potential environmental concern (APEC) at airports (ACRP Report 173: Use and Potential Impacts of AFFF Containing PFAS at Airports). Andrew has significant experience conducting site investigations involving PFAS, characterizing source zones and downgradient plume impacts, including the evaluation of precursors and addressing co-mingled contaminants.

In June 2018, Environment and Climate Change Canada finalized the Federal Environmental Quality Guideline (FEQG) for perfluorooctane sulfonate (PFOS) in freshwater surface water. The guidelines refer to the reduced solubility of PFOS in marine environments and paucity of marine toxicity data as factors precluding the development of a marine-protective surface water quality guideline. Yet PFOS has been detected by researchers in Canadian marine waters, shellfish, fish and other wildlife suggesting that migration of PFOS to marine systems is occurring. For custodians managing migration of per- and polyfluoroalkyl substances (PFAS) from federal contaminated properties, what tools are available for evaluating whether PFAS concentrations in upland surface waters are a concern for nearby marine receiving environments?

This presentation will review surface water criteria for the protection of marine environments derived for PFAS in other jurisdictions, review publicly available data where migration of PFAS from upland sites to marine environments is occurring and outline a decision-framework for evaluating risks from upland sites to marine environments.

Mathew Coady, SLR Consulting (Canada) Ltd.
Mathew Coady is a risk assessor and professional biologist with SLR Consulting (Canada) Ltd.

Groundwater contamination is often the result of concentrated releases of hazardous substances to the land surface or the shallow subsurface. However, even highly dispersed releases of per- and polyfluoroalkyl substances (PFAS) at the land surface, such as deposition of air emissions from industrial facilities, can result in groundwater contamination above the current screening values and health advisory limits. Health Canada’s drinking water screening values for perfluorooctanoic Acid (PFOA) and perfluorooctane sulfonate (PFOS) are 0.2 micrograms per litre and 0.6 micrograms per litre, respectively. The United States Environmental Protection Agency’s drinking water health advisory for combined PFOA and PFOS is 70 parts per trillion (approximately 0.07 micrograms per litre), and several U.S. states have either instituted or proposed even lower limits. Only very small quantities of PFOA and PFOS are necessary to contaminate water to such low levels.

The authors have modeled transport of PFOA through air, soil, and water in settings in which the primary sources of PFOA were determined to be air emissions of PFOA from industrial facilities. PFOA was deposited on the surrounding land surface over hundreds of square kilometres and then leached through the unsaturated zone to the water table. A complex modeling sequence involving AERMOD (American Meteorological Society (AMS) and U.S. Environmental Protection Agency (EPA) Regulatory Model) (air deposition), SWB (soil-water-balance) (infiltration rate), MODFLOW-UZF (unsaturated zone flow), MODFLOW-NWT (saturated zone flow), and MT3D-USGS (unsaturated and saturated transport) was used to simulate the complete pathway from the facility stacks to groundwater receptors. The models were calibrated to available water level and water quality data and the results were used to inform subsequent investigations and remediation efforts. A key process captured in the modeling is the affinity of PFAS molecules for organic carbon, which results in lagged transport times through the unsaturated zone. These same soil and groundwater modeling techniques are also applicable to sites contaminated by other types of PFAS releases to the land surface, such as the use of firefighting foams at airports and fire training facilities. The results of this study confirm that an integrated multi-media modeling approach for PFAS fate and transport can provide significant value in assessing potential for contamination, predicting future concentration trends, designing remedies, and estimating clean-up times.

Adam Janzen, Environmental Engineer, Barr Engineering Company
Adam Janzen is an Environmental Engineer at Barr Engineering Company in Minneapolis, Minnesota. He has over seven years of experience in groundwater flow and transport modeling with application to contaminated site assessment and remediation, water supply development, and open-pit mine dewatering. He is also one of the instructors for the Interstate Technology & Regulatory Council’s (ITRC) Geospatial Analysis for Optimization at Environmental Sites web-based training and a co-author of the accompanying guidance document. Adam has a BS from the University of Illinois at Urbana-Champaign and a MS from Princeton University, both in Civil and Environmental Engineering. He is a licensed professional engineer in Minnesota and Ohio.