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Reducing PFAS contamination risk with AFFF cleanout

The current ambiguity around effective removal of PFAS compounds from fire suppression systems necessitates an approach based on science.

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PFAS

The US Department of War (DOW) and the Federal Aviation Admin­is­tra­tion (FAA) are tran­si­tion­ing away from aqueous film-forming foams (AFFFs) that have high concen­tra­tions of PFAS in favor of fluorine-free fire­fight­ing (F3) foams. Despite the increasing avail­abil­ity of the new F3 foams on DOW’s Qualified Product List (QPL), the transition may not be as easy as it sounds.

“Tran­si­tion­ing to F3 foam is far more complicated that just cleaning fire trucks,” says Jill Greene, AFFF decon­t­a­m­i­na­tion lead at CDM Smith.

The federal maximum contaminant levels for PFAS call for extremely low envi­ron­men­tal and drinking water levels, measured in the parts-per-trillion. That means an increased likelihood of aggressive remediation of PFAS in response to discharges of AFFF to the environment, down to an almost non-detectable level.

Developing a plan for tran­si­tion­ing away from AFFF is critically important to minimizing your risks and liabilities. Below are some key steps for a successful transition to reduce impacts to human health and the environment from PFAS: 

Four-step process: Assess Fire Suppression Needs, Develop Strategy, Implement Transition, Ongoing Assurance.
Icon of a magnifying glass over a document.

Assess your system.

If sufficient decon­t­a­m­i­na­tion is not performed, residual PFAS stuck to surfaces as supramol­e­c­u­lar assemblies will contaminate the F3 foam. PFAS structures disas­so­ci­ate over time, becoming a secondary source of PFAS in F3 or rinse solutions. This is known as the “rebound effect,” which may not appear until long periods of time following the rinse. This poses a major challenge since fire suppression systems can only be out of operation briefly. 

Blue icon of a trophy inside a gear shape, symbolizing achievement in risk reduction strategy.

Strategize for maximum efficiency.

When imple­ment­ing AFFF cleanout procedures, water is not an effective solvent and should not be relied upon solely. A variety of solvents and additives have been tested for their ability to clean PFAS-impacted surfaces. However, due to differences in fire truck models, operation patterns, and adherence to protocols, direct comparisons are difficult.

We recommend that an aggressive quan­ti­ta­tive surface swabbing method be used to quan­ti­ta­tively assess the mass of PFAS on surfaces to:

  1. Appro­pri­ately char­ac­ter­ize PFAS on surfaces
  2. Demonstrate effective decon­t­a­m­i­na­tion

  3. Assess the future potential rebound into F3 foam

    Four diagrams show PFAS rebound progression in F3 foams, with increasing green dots over time.
    Over time without effective decontamiantion, expect significant PFAS rebound into 3F Foams.

     

Light bulb over gears icon, symbolizes innovation and progress.

Implement cleanout promptly. 

An efficient onsite cleaning and rinsing protocol for the interior surfaces of PFAS-impacted fire­fight­ing infra­struc­ture should be carried out promptly to avoid extended system downtime. Individual components from fire suppressant systems will need to be decon­t­a­m­i­nated or replaced to reduce the potential for residual PFAS to leach into new F3 products.

Our research has identified that the most effective method to remove these assemblies and deliver effective decon­t­a­m­i­na­tion is via a combination of:

  1. A non-volatile solvent (Increased temperature)

  2. Surface Attrition

    Diagram showing cleaning process with a fire truck, ball valves, transfer pump, hot water jetting unit, and solution tank.
    Conceptual process flow diagram of CDM Smith's closed loop cleanout approach.


Following decontamination, sampling to determine the effectiveness of cleaning should be performed on the surfaces of the equipment components themselves, such as foam tanks and piping, to demonstrate how much PFAS remains. Unfortunately, the use of target analyses like EPA Draft Method 1633 will fail to detect the vast majority of PFAS that have been used as fluorosurfactants in firefighting foams. Instead, the total mass of PFASs needs to be estimated using analytical technologies such as the TOP assay and combustion ion chromatography methods. 

Lab technician tests water samples using a pipette, wearing blue gloves.
Comparative assessment at CDM Smith’s Bellevue Lab of short- and long-term effectiveness of cleanout using potable water versus proprietary flocculant from AFFF-impacted delivery systems.

 

Crossed wrench and screwdriver icons.

Stay Connected for Ongoing Support

The science in this field is continually advancing. In 2022, CDM Smith’s Dr. Ian Ross, in collab­o­ra­tion with two global labo­ra­to­ries (ALS and Eurofins), developed and proved the efficacy of a swab method to assess the mass PFAS on the surface of impacted pipes. Sampling of water rinses is an ineffective method for demon­strat­ing successful decon­t­a­m­i­na­tion as these data provide no indication of the PFAS mass left behind that will result in rebound.
 

Person in safety gear collecting samples near machinery with tools and equipment.
Swabbing foam concentrate tank on ARFF apparatus.

Reach out to our team

Greene_Jill_2021.jpg

Jill Greene

Senior Geologist

Jill manages environmental projects from start to finish, specializing in hydrogeologic, stormwater and hazardous waste investigations and remediation.

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