Emerging Contaminants Summit

Spring 2020

rossIan Ross
Global PFAS Lead

Ian currently leads the Site Evaluation and Restoration (SER) group for Europe in a function that tailors clients' needs to the value that Arcadis can bring in managing their potential liabilities associated with land contamination and reuse of brownfield sites. He works with clients for the Arcadis group globally and is an active author and presenter at international conferences, particularly on the topic of emerging contaminants, analytical chemistry, chemical oxidation and novel remediation methods. Ian focuses on developing innovative technologies and communicating how these strategies can offer a more cost effective and sustainable approach to land portfolio management. He works as part of the Arcadis global technical knowledge and innovation (TKI) network which forms a multidisciplinary team to deliver solutions for complex sites. As a result of these activities he has won 3 national / international innovation awards for remedial design. Prior to joining Arcadis in 2002, Ian evaluated the biodegradation of xenobiotics via research and development projects for Blagden Chemicals, ICI and DSTL over a 10 year period, starting in 1992. This work involved harnessing a detailed understanding of microbial biochemistry, pollutant metabolism, analytical chemistry and molecular biology to solve problems associated with remediation of novel pollutants. During his time at Arcadis, Ian has ensured that Arcadis is at the leading edge when developing risk management strategies for the assessment and restoration of brownfield sites.



Remediation of Poly- and Perfluoro Alkyl Substances: New Remediation Technologies for Emerging Challenges 

Poly- and perfluoro alkyl substances (PFAS) comprise a diverse class of contaminants, which include PFOS (perfluorooctane sulfonate) and PFOA (perfluorooctanoic acid). PFAS are not amenable to bioremediation or conventional chemical treatment, and this limits in situ remediation options. PFAS are relatively ubiquitous in the environment at low concentrations, but source areas can exhibit higher PFAS concentrations. While the USEPA Health Advisory Limit of 70 nanograms per liter for the summation of PFOA and PFOS is not a maximum contaminant level (MCL), to be protective of potential beneficial reuse aquifers, PFAS groundwater plumes emanating from source zones will require some form of active management. The use of conventional sorbents, such as granular activated carbon (GAC) and anion exchange (AIX) resins, to address PFAS in water have become a “de facto” interim measure in response to immediate needs for PFAS removal from drinking water. Challenges of more comprehensive PFAS treatment in drinking water may also be addressed using technologies such as reverse osmosis or nano-filtration. Extending these technologies to extracted groundwater for remediation purposes, which have various degrees of geochemical and co-contaminant competition, often requires a treatment train, combining conventional sorbents and engineered filtration with more innovative and emerging remediation solutions for PFAS. These emerging solutions include many types of technologies to address source zones, mitigate mass flux in aquifers, or address PFAS in extracted water to improve the efficiency of conventional drinking water treatment technologies. There are new flocculation technologies, novel AIX resins, new engineered sorptive media, electrochemical oxidation, electrocoagulation, sonolysis, and advanced oxidation processes combined with advanced reductive processes. Remediation technologies for PFAS source zones in soil are primarily limited to excavation with onsite or offsite incineration (or other forms of thermal treatment) and in situ soil stabilization. For in situ soil stabilization to be considered viable, ongoing research and development is being conducted to evaluate the longevity of fixation amidst circumneutral pH and biotransformation, which may enhance PFAAs dissolution. Remediation of PFAS source zones and the associated groundwater plumes presently requires multiple technologies to protect human health in a cost-conscious manner. An investment in research and development to explore new technologies is part of a key initiative for groundwater preservation and protection of human health. The technologies discussed here will be presented, and their applicability/readiness to the remediation market will be assessed.



Investigation and Remediation of Multiple PFAS Source Zones at an Airport to Safeguard an at-Risk Water Supply

Elevated Concentrations of poly- and perfluoroalkyl substances (PFAS) were detected in surface water, which is used as a main drinking water supply for the population of Guernsey Island, a British Crown Dependency, located in the English Channel between the United Kingdom and France. The affected catchment area, which includes one of the Island's principal water supply reservoirs, collects surface water and groundwater from within the vicinity of the Island’s airport. The airport was identified as a potential source for the PFAS contamination. The objectives of this project were to investigate the extent of PFAS impacts within the airport and the surrounding environment; investigate whether the existing conditions were likely to deteriorate further; and identify an appropriate solution to safeguard the Island’s water supply. First, a detailed desktop review and preliminary risk assessment was completed, looking at historical uses of AFFF at the airport through records of aircraft accidents, training procedures, and material storage. The outcome of this study identified eleven potential source locations which required further assessment. Site investigations followed, including extensive soil, groundwater, and surface water sampling, which identified PFAS impacts at seven of these locations. Following detailed fate and transport modelling, four of these locations were considered to require remedial action. All investigation work was implemented without disruption to operations at the airport. Upon completion of the investigation activities, a water treatment system was designed, which incorporated the installation of two below ground capture trenches across the airfield to intercept PFAS-impacted groundwater. The water treatment system also collects and treats impacted surface water. With a capacity to treat up to 1.2 cubic meters per minute, the system is ensuring that concentrations of the PFAS are below drinking water criteria, prior to discharge into the wider catchment area. Following the installation of the water treatment system, soils identified to be contaminated with PFAS in the four source zones were excavated and contained within a purpose-built soil bund. The soils are encapsulated to isolate them entirely from the local environment, and the bund is an acoustic barrier to mitigate noise pollution from the airfield operations. The project highlighted the requirement to understand the history of AFFF use at airports and airfields as multiple sources zones are typical. The treatment solution reduced PFAS concentrations in the drinking water supply while also removing the risk of further leaching from the main source areas by isolating the contaminated material as part of wider redevelopment scheme.

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