DSAC finalizes guidance and forwards comments to commissioners on 2023 Coffin Butte annual report

The Benton County Disposal Site Advisory Committee reviewed and finalized guidance to accompany Republic Services' revised 2023 Coffin Butte Landfill annual report and confirmed the guidance was transmitted to county leaders before the board's Oct. 15 review.

Chair Ken Eklund told members the committee had summarized technical questions and public concerns about the annual report and had charged member Rachel Purcell to finalize guidance; Purcell completed that task and staff confirmed the letter was sent to the county administrator and included with materials for the commissioners. "Thanks for doing that," Eklund said during the Oct. 9 meeting, and staff confirmed the guidance went with the annual report to the commissioners.

Committee members raised questions about groundwater testing and a parenthetical note in the guidance that suggested leachate may show elevated arsenic. Members asked for clearer context distinguishing arsenic likely from natural geologic (geogenic) background levels from arsenic that could be attributable to landfill leachate, and suggested inviting the landfill geologist to present findings when the next annual report is prepared.

Members also requested clearer mapping of monitoring wells, seasonal groundwater contours and flow direction, and noted that leachate and groundwater data are included in the annual report's appendices but can be technical for non‑specialist readers. Committee members recommended that future annual‑report briefings include a high‑level, plain‑language summary from the landfill geologist to explain trends and monitoring layout.

The committee took no additional formal action Oct. 9. Members were told the Board of Commissioners would review the updated annual report at its Oct. 15 meeting and that public comment to the board remained an avenue for additional input.