PFAS Plumes Cleaned Up Using Proven, Sustainable, Approach
By Maureen Dooley – REGENESIS Vice President, Industrial Sector
If history is any guide, the threat of “Forever Chemicals” (i.e., PFAS) spreading from industrial facilities, military bases, and airports will largely be remedied by allowing natural attenuation to take its course. Natural attenuation encompasses processes that lead to reduction of the mass, toxicity, mobility, or volume of contaminants without human intervention.[1] However, PFAS’ everlasting nature suggest that at many sites, an enhanced natural attenuation remedy, such as in situ (i.e., in-place) treatment of PFAS source area groundwater, will be required to facilitate natural attenuation of a PFAS plume.
The environmental industry first saw natural attenuation displace pump-and-treat (P&T) as a remedy for hydrocarbon treatment in the mid-1990s after the Air Force Center for Environmental Excellence (AFCEE) developed a protocol for natural attenuation of fuel hydrocarbons in 1994, then followed with a protocol for natural attenuation of chlorinated solvents in 1996. These concepts and processes proved effective and were further adapted by the US EPA and state regulatory agencies throughout the early 2000s and were broadened to incorporate a wide range of contaminants, including metals.
With the enormous cost of operating inefficient P&T systems and the attendant generation of hazardous waste, history is poised to repeat itself as leading environmental experts publish protocols for the natural attenuation of PFAS. It only makes sense. This approach will save governments billions of dollars, avoid the enormous carbon footprint associated with inefficiently pumping and treating water, prevent the generation of toxic PFAS-laden filtering media, and eliminate the environmental risk of PFAS.
Remediating PFAS using a Monitored Natural Attenuation (MNA) approach[1] will require demonstrating minimal exposure to these chemicals now or in the future through groundwater plume monitoring. Points where exposure to PFAS could occur include potable water wells and streams located near PFAS release sources (e.g., firefighting rescue and training areas at airport facilities worldwide).
MNA can be a practical and cost-effective remedial path toward site closure but only if PFAS plumes can be shown through monitoring to be stable or declining. However, without enhanced attenuation[2] interventions, it is unlikely that stable-or-declining-plume conditions will be met due to PFAS’s extraordinary persistence and mobility.
Perhaps the most practical and effective enhanced attenuation intervention involves the targeted in situ sorption treatment at PFAS source zones, such as demonstrated by the injection of PlumeStop® Colloidal Activated Carbon (CAC) at Fairbanks International Airport (FIA.)
In a webinar hosted by REGENESIS® scheduled for broadcast on January 27, 2021, 2 p.m. EDT, Kristen Freiburger, Associate at Shannon & Wilson, will discuss the fate and transport properties of PFAS that lead to groundwater plume development and PFAS exposure risk. Kristen will be joined by Maureen Dooley, REGENESIS Vice President, Industrial Sector, who will present examples of the CAC application at PFAS contaminated sites where the aquifer properties were modified to drastically reduce PFAS’ ability to migrate (i.e., transport) through the aquifer. Ms. Freiburger will outline how PFAS have been virtually eliminated from groundwater following the CAC application at FIA, including over 500 nanograms per liter PFOA and PFOS reduced to non-detect, through 19 months of performance monitoring completed thus far.
Experienced remediation practitioners know that eliminating contaminants at the plume source using enhanced attenuation intervention methods drastically reduces the contaminant flux in the plume. This action forces the plume’s extent to decline, which is demonstrated through MNA. Results observed at FIA and other AFFF (i.e., aqueous film forming foam) release sites like Camp Grayling Army Airfield demonstrate the viability of an EA remedial approach using CAC to target PFAS source zones, now being adopted at other airport sites globally.
About the author – Ms. Dooley has over thirty years’ experience in many aspects of environmental industry including project management, research and development, senior technical oversight, remedial design and laboratory management. Ms. Dooley’s current position is the Vice President Industrial Sector for REGENESIS.
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[1] According to the EPA, MNA is a remedial approach that: . . . relies on natural attenuation processes (within the context of a carefully controlled and monitored site cleanup approach) to achieve site-specific remedial objectives within a time frame that is reasonable compared to other methods. The “natural attenuation processes” act without human intervention to reduce the mass, toxicity, mobility, volume, or concentration of contaminants in soil and groundwater. These in-situ processes include biodegradation, dispersion, dilution, sorption, volatilization, and chemical or biological stabilization, transformation, or destruction of contaminants. U.S. EPA. Use of Monitored Natural Attenuation at Superfund, RCRA Corrective Action, and Underground Storage Tank Sites, EPA/9200.4-17P. Published online 1999:41.
[2] According to the ITRC, “Enhanced Attenuation is any type of intervention that might be implemented in a source-plume system to increase the magnitude of attenuation by natural processes beyond that which occurs without intervention. Enhanced attenuation is the result of applying an enhancement that sustainably manipulates a natural attenuation process, leading to an increased reduction in mass flux of contaminants.” ITRC (Interstate Technology & Regulatory Council). Enhanced Attenuation: Chlorinated Organics. EACO-1. Washington, D.C.: Interstate Technology & Regulatory Council, Enhanced Attenuation: Chlorinated Organics Team. www.itrcweb.org. Published online 2008.
