The Minnesota Pollution Control Agency's Closed Landfill Program oversees more than 110 old landfills in the state. Addressing risk at the Freeway Landfill in Burnsville is currently the program's highest priority.
One of the first landfills permitted by the MPCA, Freeway was constructed in the early 1970s, before liners were required to be installed beneath municipal waste landfills. The site involves a unique setting with relatively shallow bedrock and is adjacent to the Minnesota River and a deep-rock-quarrying operation where significant dewatering has taken place for decades. The existing groundwater conditions have been heavily influenced by the long-term dewatering, which has left the water table artificially depressed in the bedrock below the landfill. Concerns have emerged that groundwater will come into contact with the waste when quarry operations end, posing new risks to the river, nearby public water-supply wells, and the lake that will form at the quarry pit.
Barr assisted the MPCA with site investigation, alternative assessment, and preliminary design, including development of several preliminary layouts and budget estimates for landfill closure. Options include (1) reconstructing the landfill on site with liners and landfill-gas controls and (2) removing waste from the site and either disposing of it at another landfill or treating it thermally at a waste-to-energy facility. Our work has also involved evaluating the cost and benefits of a range of liner designs for the onsite alternative, completing field studies. Barr is completing a detailed design for MCPA’s selected approach and is assisting with community engagement and environmental permitting in support of project construction.
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