CHAPTER 5
Summary of Findings
The findings of this synthesis highlight the following key conclusions regarding PFAS impacts and challenges in DOT construction and maintenance operations.
PFAS Impacts and Challenges
The extent of PFAS impacts on DOT construction and maintenance operations varies widely among states. For 23% (10/44) of responding DOTs, PFAS are a sufficiently pressing topic to garner specific departmental procedures, policies, or guidance to address in construction and maintenance. However, among the state DOTs that do have specific guidance, the majority—70% (7/10)—have informal procedures, policies, or guidance. Three responding DOTs indicated having formal PFAS-related procedures, policies, or guidance within their agency. Most states have no formal guidance or regulation related to PFAS within an agency other than their DOT. However, 39% of responding DOTs (17/44) indicated that their state does have formal or informal PFAS-related policies, procedures, or guidance.
Nonetheless, considerations of PFAS have affected many state DOTs. Of the responding DOTs, 21% (9/42) reported knowingly encountering PFAS contamination on projects or within right-of-way areas. Of those DOTs that had encountered PFAS contamination, 33% (3/9) indicated that they had established a precedent for managing PFAS impacts on projects. Active remediation or removal of PFAS-containing materials or media at construction, maintenance, or storage sites is being considered by 30% (11/37) of the responding state DOTs. Moreover, 11% (4/37) of these state DOTs conduct testing or chemical monitoring for PFAS contamination on construction or maintenance project sites. Costs for such testing are significant: All respondents reported paying at least $200 per sample for PFAS testing. All the responding state DOTs use private or contract laboratories for PFAS testing, whereas one DOT mentioned also using public or state laboratories.
Despite the variability among DOTs in addressing PFAS in highway construction and maintenance, several consistent themes were evident across the survey respondents and case examples. All the case example participants articulated concerns about the general cost of managing the effects of PFAS on construction and maintenance projects. Other, more specific, themes have implications for how managing PFAS may affect project costs, timelines, and personnel commitments for highway construction and maintenance:
- Pending federal regulation. Although the EPA recently proposed regulations on PFAS in drinking water, no federal regulations yet exist on groundwater, soils, or hazardous substance designations. More federal and state regulation of PFAS is widely anticipated. Of the DOTs interviewed in case examples, 88% (7/8) explicitly stated that they expect new federal or state regulations related to PFAS in the future. As a consequence, some DOTs are refraining from policy changes until federal regulations are finalized.
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Collaboration with state regulatory agencies. Eighty-eight percent (7/8) of the DOT representatives interviewed in the case examples stated that communicating with state environmental agencies is crucial to help their DOT understand the changing PFAS regulatory landscape. However, the extent that DOTs communicate and collaborate with state environmental agencies varies. For example, 27% (11/41) of DOTs responding to the survey 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, 40% (8/20) involve the state DOT.
Of the case example participants, 75% (6/8) indicated their belief that PFAS regulation will likely come—or has already come—from the state level in addition to the federal level, although the type and extent of anticipated regulations varied from state to state. The same percentage cited the benefit of communicating with state environmental agencies to be aware of regulatory changes.
- Restrictions on landfill disposal. In addition to water and soil regulations, 27% (10/37) of survey respondents indicated that their DOT or contractors are subject to PFAS-related regulatory or receiving restrictions for landfilling materials. Further, 75% (6/8) of the case example participants mentioned concern about the cost and logistical challenges of disposing of PFAS-contaminated waste; the costs to ship PFAS-contaminated soils long distances to the landfills that accept such waste may be high. Of those DOTs, 83% (5/6) indicated that they had already experienced challenges because of PFAS restrictions from landfills. Among the case example participants, 38% (3/8) specifically articulated concerns about landfills that do not accept waste with any measurable PFAS, even if concentrations do not exceed background levels.
PFAS Contamination Identification and Mitigation
A substantial majority—78% (7/9)—of responding DOTs that have encountered PFAS require special management of soil or water when PFAS are detected on a project. Potentially as a consequence of these requirements, 38% (3/8) of case example respondents indicated that they only test for PFAS when they have other cause to believe PFAS are likely present, such as past PFAS-related activities or industries. These determinations are typically informed by databases of previous land uses or PFAS-related activities, frequently maintained by state environmental agencies.
Few DOTs identify materials or containers that may contain or be contaminated with PFAS. Eleven percent (4/37) of survey respondents have a DOT-specific procedure for identifying PFAS-containing materials, and 5% (2/37) of these state DOTs have procedures in place for identifying containers that may have held PFAS-containing materials. However, two case example DOTs (25%) mentioned their states having existing or pending policies to explicitly avoid acquiring PFAS-containing materials.
When identified, PFAS contamination might be mitigated through soil disposal or storage on-site. Two case example participants indicated that storage on-site was preferred and allowable under their current procedures. Nonetheless, specific regulations designating when and how contaminated soils can be moved and relocated vary. Among survey respondents, 27% (10/37) are subject to PFAS-related restrictions for landfilling, whereas 22% (8/37) are subject to restrictions for land application. One case example participant indicated that their DOT used granular activated carbon to remediate aqueous PFAS before water was discharged.
PFAS mitigation is not necessarily a legal requirement for some DOTs, even if they have PFAS-related policies. Three case example DOTs mentioned current or pending regulatory policies that will not hold DOTs responsible for contamination that the DOT did not cause,
particularly if that contamination has migrated from properties outside the right-of-way. Of the survey respondents, 70% (26/37) of do not consider active remediation of PFAS on sites, and 65% (24/37) do not consider liability for PFAS-related impacts in the acquisition, sale, maintenance, or disturbance of rights-of-way or project sites.
Sampling, Testing, and Screening Approaches
With regard to sites identified as likely locations of PFAS contamination, all survey respondents that screen for PFAS indicated that sampling occurs in the soil phase, although 75% (3/4) test water as well. Of the case example participants, two DOTs mentioned that sampling typically requires additional training in PFAS-related protocols for contractors, including how to avoid sample contamination. Testing may be performed by either commercial or state labs, although all survey respondents indicated that they employ commercial labs certified for performing standard EPA methods for PFAS analysis.
In addition to the need for specific training in sample collection, the cost of laboratory testing fees for PFAS is typically higher than for many other environmental contaminants, and processing times can be slower.
Knowledge Gaps and Further Suggested Study
Most of the survey and interview participants came from environmental backgrounds and divisions. Therefore, the knowledge gaps noted are presented from this context and with a primary focus on core DOT functions of construction and maintenance operations for highways. Nonetheless, firefighting foams, which are often found at airports, are a significant source of PFAS contamination; airports tend to fall outside the jurisdiction of environmental divisions and instead are the responsibility of aeronautical divisions. As such, separate but harmonized identification and mitigation procedures may be needed by the aeronautical divisions.
This synthesis identified a major knowledge gap related to the effects of PFAS contamination on DOT operations. There is no unified or comprehensive guidance document for DOTs outlining PFAS regulations from states, landfills, and the federal government; tools for identifying potential sources or likely sites of PFAS contamination; standard methods and protocols for chemical screening of contamination; and means for mitigating and remediating PFAS. Such a document would consolidate knowledge across jurisdictions and assist DOTs that have thus far not substantially altered their procedures to mitigate PFAS contamination.
The objective of suggested future study would be to provide DOTs with a reference document with technical guidance on the status of PFAS regulatory requirements and risks, current PFAS impacts on DOTs, identification of common sources of PFAS (e.g., airports, military bases, leaching from landfills), and a collection PFAS testing methods and notification requirements. Additionally, this suggested study could produce a general roadmap for PFAS impacts at DOTs. This roadmap would identify, strategize, and prioritize needs to address DOT-related issues of PFAS, including additional issues identified in this synthesis, such as rejected material at landfills, potential on-site material management strategies, and the DOT’s role in PFAS mitigation.
