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EPA presents five‑year review for Libby groundwater Superfund site; agency flags limited institutional controls and need for PFAS study
Summary
EPA remedial project manager Jason Rafy told Lincoln County commissioners the sitewide five‑year review finds institutional controls remain limited on some parcels, the soil remedy and land farm cleanup are nearly complete, and additional work (a lower‑aquifer addendum and PFAS investigation) is needed before a final protectiveness determination for the whole site.
Jason Rafy, EPA remedial project manager for the Libby groundwater Superfund site, told the Lincoln County Board of Commissioners on Aug. 6 that the agency’s seventh five‑year review is complete and identifies remaining work to ensure long‑term protectiveness. "We found that institutional controls are still limited," Rafy said, describing properties outside city limits that lack restrictions to prevent new well drilling and noting that deed restrictions on some parcels are not sufficiently protective. Rafy summarized the remedy progress, including startup of area 2 in situ bioremediation and drilling in area 1, and said the soil remedy and land‑farm work are essentially complete and will be seeded this fall.
The EPA presentation outlined three outstanding technical efforts. Rafy said the agency will prepare a five‑year review addendum to evaluate the lower aquifer, which lacks sufficient data for a protectiveness determination, and a separate addendum to investigate possible PFAS (per‑ and polyfluoroalkyl substances) impacts tied to historic fire‑practice or other site activities. "We decided to take a closer look at the lower aquifer remedy," Rafy said, adding the review has taken longer because earlier documentation was not as thorough as the agency would like. He told the board that the in situ biospar (bioremediation) system will be brought online for area 1 in spring and that the record of decision’s review period will be tied to that startup.
On remedial protections, Rafy said the EPA classified operable unit 1 (human‑exposure pathway) as short‑term protective because some county parcels still lack institutional controls; operable unit 2 and the sitewide status were deferred pending completion of the lower‑aquifer review and the PFAS investigation. He recommended the county and state consider additional controls — for example, establishing a controlled groundwater area or strengthening deed restrictions — and said EPA will work with local officials and the state DNRC on options. Commissioners asked technical questions about the CAMU location, whether the newly drilled private wells (reported at about 35 gallons per minute) could affect the remedy, and how sentinel monitoring wells will be used; Rafy said modeling and monitoring to date do not indicate an operational problem, but the agency will add data where needed and adjust the remedy if monitoring suggests plume changes.
Next steps include producing addenda for the lower aquifer and possible PFAS impacts, continuing monitoring and sentinel well installations as warranted, planting the land farm, and closing the on‑site landfill in the coming years. The county will be involved in discussions about additional institutional controls and possible controlled groundwater area designation.
