Republic Services outlines Coffin Butte Landfill expansion and gas management plans

The Benton County government meeting on May 2, 2025, focused on the Conditional Use Permit Application for the expansion of the Coffin Butte Landfill by Republic Services. The meeting addressed several key points regarding the landfill's operational timeline, design changes, and environmental impacts.

The discussion began with a review of the landfill's projected lifespan. Republic Services representatives indicated that without the proposed expansion, the landfill has approximately 10 to 11 years of operational life remaining, with an estimated end of waste placement around 2052. The expansion proposal aims to extend this timeline by an additional six years.

A significant change from the original 2021 proposal was highlighted: the slope of the landfill expansion area has been modified, reducing the height by 90 feet. This adjustment was necessary due to a smaller footprint for the expansion, which now only extends to the south side of Coffin Butte Road. The design change impacts the landfill's elevation and slope, limiting how high waste can be placed.

Concerns regarding gas generation from the landfill were also discussed. Republic Services confirmed that two-thirds of the landfill gas produced is currently utilized by a local utility company, with plans to enhance this capacity. The company is exploring options to scrub the gas for pipeline use, rather than solely relying on flare burn-off.

The meeting also addressed the issue of leachate management. A clarification was made regarding the landfill's role as a receiver of leachate rather than a producer of PFAS (per- and polyfluoroalkyl substances). It was noted that PFAS found in leachate originates from the waste stream itself.

Noise and odor modeling were additional topics of concern. Commissioners raised questions about the adequacy of noise assessments and the potential for fugitive emissions from the landfill. Republic Services assured that they conduct regular monitoring to identify and mitigate any high methane levels on the landfill surface.

Overall, the meeting provided a comprehensive overview of the proposed landfill expansion, addressing operational timelines, environmental considerations, and community concerns. The next steps involve further analysis and potential adjustments based on feedback from the meeting.