The MPCA’s Closed Landfill program oversees more than 110 old landfills in Minnesota. Freeway Landfill, which sits adjacent to the Minnesota River and a deep rock-quarrying operation in Burnsville, is currently their highest priority for addressing risk. One of Minnesota’s first landfills permitted by the MPCA, Freeway Landfill was constructed in the early 1970s before liners were required beneath municipal waste landfills. The existing groundwater conditions have been heavily influenced by the quarry’s long-term dewatering, leaving the water table artificially depressed in the bedrock below the landfill waste. Concerns have emerged that groundwater will come into contact with the waste in the future when quarry operations end, posing new risks to the river and nearby public water-supply wells. Another concern is the presence of emerging contaminants of concern, including 1,4-dioxane and per- and polyfluoroalkyl substances (PFAS).
Barr assisted the MPCA with site investigation, alternative assessment, and preliminary design, including developing several preliminary layouts and budget estimates for landfill closure. We also conducted an analysis of potentially relevant federal, state, and local regulations and technical requirements for the alternatives under consideration. Barr’s supporting efforts include evaluating costs, benefits, and regulatory compliance for a range of liner designs for the on-site alternative. To assist the environmental review and permitting for the project, we completed field studies, including wetland delineations, tree and raptor surveys, and a floodway evaluation. Barr is completing a detailed design for MPCA’s selected approach and is assisting with community engagement and environmental permitting in support of project construction.