Monroe County Ridgeville Landfill Liner CQA & Partial Cap

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The Monroe County Solid Waste Department hired Ayres to provide construction quality assurance (CQA) and documentation for the Phase 4 liner at the Ridgeville 2 Landfill and also design the reshaping of a problematic landfill cap.

Construction observation services include survey documentation to verify construction material layer elevations and thickness, collection of bulk samples for soil testing, waste relocation observation and related soil samples, a proof-roll of the sub-base floor, observation of sub-base and clay placement, collection of samples from the clay liner and cap material, CQA of geomembrane deployment and testing, leak location services for the Phase 4 liner, and post-construction documentation.

At the same time, Ayres provided services for a partial cap of the Ridgeville 1 Landfill, a combination natural attenuation landfill with a clay cap and composite liner and cap that started accepting waste in 1979. The landfill grew to 26 acres and was closed in 2006. The oldest parts of the landfill were designed as a natural attenuation landfill, but these first phases were determined to be the cause of groundwater contamination with PCE (tetrachloroethylene), TCE (trichloroethylene), and vinyl chloride. The landfill cap was designed with a flat slope, and areas of the cap experienced differential settlement to the point of ponding water and wetland vegetation on the cap. The landfill was experiencing a large amount of surface water infiltration through the clay cap and creating excess leachate.

Ayres worked with Monroe County to develop a Remedial Options and Action Plan to reduce the amount of leachate generated in the landfill. The existing clay cap was salvaged and regraded to a consistent slope, and a 3.5-acre composite cap of linear low-density polyethylene (LLDPE) geomembrane style cap was constructed over the areas of greatest concerns and flat slopes. A passive gas system was also installed in this cap area. As of the last groundwater sampling event, leachate volumes have dried up almost completely, and groundwater impacts of PCE, TCE, and vinyl chloride have been decreasing.

Project Information

Client's Name

Monroe County Solid Waste Department


Monroe County, WI

Primary Service



Local Government