Case Study: St Louis County Landfill Geothermal Heat Recovery and Leachate PFAS Treatment Systems Project

Landfills are not often associated with sustainable design. St. Louis County (Minnesota) is working to change this mentality by simultaneously tackling two significant environmental issues: climate change and per- and polyfluoroalkyl substances (PFAS) management.

St Louis County broke ground in early 2025 at its Virginia Regional Landfill for the construction of the first fully permitted, land-applied PFAS leachate treatment facility in the state of Minnesota. To minimize added emissions and reduce energy use, the new leachate treatment system will use heat produced by the landfill’s decomposing waste captured by its landfill-based geothermal system (constructed in 2024) to heat the treatment building and some treatment processes.

The Virginia Regional Landfill is a municipal solid waste landfill located up-state [CK1] in Minnesota that spray-irrigates its landfill leachate onsite. Since the emergence of PFAS as a significant health concern, the Minnesota Pollution Control Agency (MPCA) has indicated that leachate spray irrigation will no longer be allowed without significant treatment. Publicly owned treatment works (POTWs) within Minnesota have also signaled concern regarding continued acceptance of leachate for treatment. This project and its state-of-the-art design will allow St. Louis County to successfully continue onsite leachate management and land application at its Virginia, Minnesota, facility. This presentation will:

• Review the regulatory landscape and driving factors that led to the project
• Review past pilot treatment evaluations and results
• Provide an overview of the facility and its full-scale, advanced leachate treatment system
• Present design considerations and selection for the facility’s major treatment processes and infrastructure, including PFAS treatment and other compounds of interest such as boron
• Concentrate management and next steps for evaluating PFAS destructive technologies
• Provide an overview of the landfill-based geothermal system, general concept, design considerations, and final and as-built designs for the landfill cell constructed in 2024

By leveraging landfill heat, the treatment system can operate at a lower operating cost while improving overall performance and reducing added emissions.