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EPA: Libby groundwater remedy broadly protective but gaps remain in controls; lower‑aquifer review and PFAS testing pending
Summary
The EPA presented the finalized five‑year review of the Libby groundwater Superfund site, finding the remedy operating as intended in many respects but identifying gaps in institutional controls, deferring lower‑aquifer conclusions pending more data, and recommending stronger deed restrictions and possible PFAS testing.
Jason Rafy, the EPA remedial project manager for the Libby groundwater Superfund site, told Lincoln County commissioners that the agency has finalized its seven‑time five‑year review and is issuing recommendations to fill data gaps and shore up long‑term protections.
Rafy said the five‑year review asks three central questions: is the remedy functioning as intended; are exposure assumptions and cleanup values still valid; and has new information emerged that would call protectiveness into question. The review found that engineered controls and recent soil work have progressed, and that an in‑situ biosparging system (started in area 2 last year) and newly drilled wells in area 1 should be brought online in the coming year to address the primary source area on International Paper property.
At the same time, Rafy said institutional controls (ICs) remain incomplete on a number of county parcels outside city limits, which leaves an exposure pathway risk even if no current exposures are known. For the upper‑aquifer human‑exposure operable unit (OU‑1), EPA judged the remedy "short‑term protective" pending stronger ICs; for the lower aquifer (OU‑2) the agency deferred a protectiveness determination until a focused addendum study is completed. Rafy also flagged the need to investigate possible per‑ and polyfluoroalkyl substances (PFAS) — referred to in the briefing as "POS" — because historical burning of wood‑treatment wastes and fire‑practice activities may have introduced such chemicals.
The agency recommended additional deed restrictions on and off International Paper property, consideration of a controlled groundwater area or other county controls, and working with the board of health and DNRC on options. EPA said it will produce a five‑year‑review addendum to complete the lower‑aquifer evaluation and the PFAS investigation; it did not provide firm completion dates but tied full remedy review to the startup of area‑1 operations anticipated in spring of next year.
Commissioners and attendees raised questions about whether existing private wells or additional new wells could interfere with the remedy; EPA said the local wells are generally low‑flow (roughly 35 gallons per minute), that monitoring wells are in place and that any impact would be identified and addressed through remedy modification or property owner coordination. Commissioners also discussed expanding city well‑protection ordinances or using strengthened ICs to address boundary inconsistencies.
The presentation concluded with next steps: EPA will complete the addendum for the lower aquifer, investigate PFAS presence and sampling needs, finalize deed‑restriction updates, and proceed to operate the in‑situ system in area 1 as scheduled.
