SUMMARY

Practices to Identify and Mitigate PFAS Impacts on Highway Construction Projects and Maintenance Operations

Per- and polyfluoroalkyl substances (PFAS) are a class of more than 6,000 contaminants of emerging concern that can harm both ecosystems and human health. These anthropogenic compounds contain carbon–fluorine bonds that make them stable and persistent in the environment, earning them the nickname “forever chemicals.” PFAS regularly migrate from the sources of their contamination, including fire training areas at military sites and airports, PFAS manufacturing sites, and land-applied wastewater biosolids and landfills, such that they are commonly found at low levels, even in soils and water far from any likely source. PFAS bioaccumulate in the food chain and are found in the blood of nearly all humans, where they are associated with cancer, thyroid disease, increased cholesterol, and other health problems, even at low levels of exposure.

There are currently no binding federal regulations for PFAS, leaving regulation largely to the states. However, federal maximum contaminant levels (MCLs) have been proposed for drinking water and more rulemaking is under way. The EPA has begun designating several PFAS as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980. The designation of PFAS as hazardous substances would restrict how departments of transportation (DOTs) could handle and dispose of impacted materials and would give the EPA authority to direct cleanup of PFAS contamination. Additionally, cleanup, disposal, and discharge could be affected if the EPA designates PFAS as hazardous waste under the Resource Conservation and Recovery Act of 1976 or designates a specific level of PFAS as harmful to aquatic life.

State-level regulations for PFAS vary widely. At least 15 states have set their own MCLs for PFAS. Additionally, several states regulate PFAS in groundwater and applications such as firefighting foam and food contact papers.

The objective of this synthesis is to document current state DOT practices for identifying locations of potential PFAS contamination and mitigating the impacts of PFAS related to highway construction and maintenance operations. This study considers PFAS impact and mitigation efforts in all phases of highway project development (i.e., planning, design, right-of-way acquisition), construction, and maintenance.

The study gathered information on written DOT policies, methodologies for identifying and mitigating PFAS impacts, screening approaches, and the identification of PFAS-containing materials. To collect data, the synthesis used a literature review, a practitioner survey, and case examples from interviews. The practitioner survey was sent to the DOTs of all 50 states and the District of Columbia. A total of 44 survey responses were received, yielding an 86% response rate. In addition, eight case example interviews were conducted to

gather more detailed feedback. The case example participants were systematically selected to yield feedback from all four AASHTO regions and from states with formal, informal, and no policies related to PFAS.

The survey responses revealed that 39% (17/44) of the responding states have formal or informal procedures, policies, or guidance for identifying and mitigating potential PFAS contamination within a state agency other than the DOT; the remaining 61% (27/44) do not have such measures in place or are unsure. However, 23% (10/44) of the responding states have such procedures, policies, or guidance within the state DOT itself. Among the states that do have DOT-specific guidance, 70% (7/10) have informal procedures, policies, or guidance.

Additionally, 27% (11/41) of responding states have action plans related to PFAS; of those plans, 45% (5/11) were developed with the involvement of the state DOT. Similarly, 50% (20/40) of responding states have an interagency group addressing human exposure to PFAS; of those groups, 40% (8/20) involve the state DOT.

Of the responding state DOTs, 21% (9/42) reported encountering PFAS contamination on projects or within existing right-of-way areas. Another 30% (11/37) of the responding state DOTs are considering active remediation or removal of PFAS-containing materials or media at construction, maintenance, or storage sites. Moreover, 11% (4/37) of the responding state DOTs conduct testing or chemical monitoring for PFAS contamination on construction or maintenance project sites. All the responding state DOTs use private or contract laboratories for PFAS testing (4/4), whereas 25% (1/4) of these DOTs also use public or state laboratories.

One notable theme from the case examples was state DOTs anticipating new regulations related to PFAS. Of the DOTs interviewed in the case examples, 88% (7/8) explicitly stated that they expect new federal or state regulations related to PFAS in the future. All (8/8) case example states with no or informal PFAS-related policies expressed reluctance to finalize their policies until the pending federal regulations are established. Moreover, 88% (7/8) of the DOTs interviewed in the case examples stated the importance of communicating with state environmental agencies to understand the changing PFAS regulatory landscape.

Another theme from the case examples was state DOTs facing challenges related to restrictions on landfill disposal of PFAS-containing waste, such as soil from construction projects. Of the DOTs interviewed in the case examples, 75% (6/8) mentioned concern about the cost and logistical challenges of disposing of PFAS-contaminated waste. Of those DOTs, 83% (5/6) indicated that they had already experienced challenges because of PFAS restrictions from landfills.

The synthesis identified knowledge gaps that could be addressed by a study that produces a comprehensive guidance document to consolidate knowledge about PFAS across jurisdictions and assist DOTs in developing policies related to PFAS impacts on highway construction and maintenance projects. Such a document could include guidance on identifying common sources of PFAS, evaluating which products might contain PFAS, selecting and implementing testing methods, and deciding when and where DOTs should or should not test for PFAS.