The objective of this Statement of Need was to seek applied research to develop cost-effective in situ or ex situ remedial technologies for groundwater impacted by per- and polyfluoroalkyl substances (PFAS) resulting from the use of aqueous film forming foam formulations by the Department of Defense. Proposed efforts focused on the following objectives:

• Develop cost effective, in situ or ex situ remedial approaches for treating per- and polyfluoroalkyl substance impacted groundwater, including consideration of the impact of common co-occurring chemicals of concern on the remedial process given these compounds were commonly utilized at sites impacted with petroleum hydrocarbons and possibly chlorinated solvents (e.g., historical fire training sites).
• Develop treatment train approaches that cost-effectively treat PFAS and facilitate treatment of co-occurring chemicals of concern. Include the justification for a treatment train approach over a single technology.

Proposals clearly stated which specific PFAS would be included in the pre- and post-treatment analytical testing. Although the emphasis should have been on PFOA and PFOS, consideration should have been given to including other commonly occurring, high priority, PFAS compounds (e.g., PFNA, and PFHxS). Justification should have been provided for which PFAS compounds would be included in the laboratory studies.

Research and development activities at laboratory-, bench-, and field-scale were considered, although work did not necessarily have to culminate in a field-scale effort. In situ technologies and approaches should not have been applicable to a variety of hydrogeologic settings. Proposers should have been cognizant of previous SERDP-funded research that focused on developing a better understanding of fate and transport properties of PFAS in groundwater, and of the mechanisms involved in chemicals of concern destruction as well as previously funded research that focused on developing in situ technologies.

Funded projects will appear below as project overviews are posted to the website.

Research should lead to improved management of PFAS sites by facilitating the establishment of more cost-effective and efficient remedial action plans that are protective of human health and the environment. The remediation approaches that will be developed through this SON will improve the reliability of contaminant treatment processes and expedite the cleanup and closure of contaminated DoD sites.

AFFF formulations have been used by DoD since the 1970s to suppress fires, and there are hundreds of sites with associated PFAS contamination. DoD used AFFF mixtures containing significant quantities of PFOS and related perfluoroalkyl sulfonates such as perfluorohexane sulfonate (PFHxS) until 2002, when production stopped. However the DoD continued (until only recently) to use PFOS-containing AFFF stocks. Although the DoD’s legacy use of AFFF included various fluorotelomer-based formulations, the vast majority of DoD’s environmental liability likely results from the use of PFOS-based AFFF. Additional research on PFAS is timely given USEPA’s recent drinking water health advisories for two common PFASs, perfluorooctanoic acid (PFOA) and PFOS as well as the numerous states that are beginning to promulgate drinking water standards.

Many of the PFASs found in AFFF formulations are highly soluble and migrate rapidly, while others are far less mobile. The more soluble PFASs are likely to become depleted through flushing from source zones over time. However, other PFAS compounds may be retained in the source zone, with varying degrees of potential for mass transfer into the aqueous phase, infiltration to groundwater (for vadose zone source areas), and/or groundwater migration, particularly after several years in the subsurface. PFOS and PFOA are relatively mobile, though their fates are complicated by the presence of potential precursors for these compounds in complex PFAS mixtures such as AFFF formulations.

Due to their chemical structure, PFASs are very stable in the environment and are relatively resistant to biodegradation, photo-oxidation, direct photolysis, and hydrolysis. The perfluoroalkyl carboxylic acids and sulfonic acids have very low volatility due to their ionic nature and are relatively mobile in soil and leach into groundwater. Granular activated carbon (GAC) has been proposed for use or is being used at several sites to specifically remove PFOS and PFOA from contaminated water in ex situ processes; however, the cost-effectiveness of GAC systems remain questionable, specifically with regard to regeneration. Use of some types of technologies results in generation of ancillary waste streams (e.g., brines are generated during regeneration of ion exchange resins). Solutions are needed which include provisions for regeneration of spent media, and treatment and disposal of ancillary waste streams. Moreover, effective treatment options are needed that address a larger suite of PFASs commonly found at AFFF-impacted sites.

The cost and time to meet the requirements of this SON are at the discretion of the proposer. Two options are available:

Standard Proposals: These proposals describe a complete research effort. The proposer should incorporate the appropriate time, schedule, and cost requirements to accomplish the scope of work proposed. SERDP projects normally run from two to five years in length and vary considerably in cost consistent with the scope of the effort. It is expected that most proposals will fall into this category.

Limited Scope Proposals: Proposers with innovative approaches to the SON that entail high technical risk or have minimal supporting data may submit a Limited Scope Proposal for funding up to $200,000 and approximately one year in duration. Such proposals may be eligible for follow-on funding if they result in a successful initial project. The objective of these proposals should be to acquire the data necessary to demonstrate proof-of-concept or reduction of risk that will lead to development of a future Standard Proposal. Proposers should submit Limited Scope Proposals in accordance with the SERDP Core Solicitation instructions and deadlines.