Board hears presentation on proposed Demcon anaerobic digester in Louisville Township

The Scott County Board of Commissioners received an informational presentation on a land-use application by Demcon Companies to build an anaerobic digester facility on reclaimed portions of the former Bridal Rock Quarry in Louisville Township.

Greg Wagner, Scott County planning and zoning staff, told commissioners the site is zoned I-2 (heavy industrial) and the digester portion would occupy roughly 26 acres within a larger 30-acre project area reclaimed from quarrying. The project underwent an Environmental Assessment Worksheet (EAW) reviewed by the Minnesota Pollution Control Agency (MPCA); the MPCA issued a negative declaration that allowed Demcon to proceed to a county conditional-use and plat review.

Bill Keegan of Demcon Companies described the technology and market plans. He said the facility would accept source-separated food waste, some yard/wood waste and other organics, process them in high-solids anaerobic digesters to produce renewable natural gas (RNG) and treat digestate into biochar. "We would produce around 200,000 MMBtu per year of renewable natural gas," Keegan said, and described the biochar as a high-temperature, low-oxygen byproduct used as a soil amendment, filtration media or for carbon sequestration.

Keegan and county staff outlined safeguards and site design. The facility will include an air quality control system and scrubber stacks; the project obtained a variance from the county Board of Adjustment for a scrubber stack height that exceeds the 45-foot building-height limit. Keegan said the building and digesters will be set in a reclaimed depression roughly 20 feet below surrounding grades and that the eastern frontage along U.S. Highway 169 will be screened with substantial plantings.

Traffic and feedstock details presented to the board included an estimated 30 to 50 truck trips per day (inbound for deliveries and outbound for byproducts and employee traffic). Keegan said the facility’s inbound processing would be about 75,000 tons per year of organic materials, including roughly 10,000 tons of wood-type material to balance the feedstock. He described a projected two-year construction schedule if local permits are approved and estimated production beginning in mid-2027.

Keegan also said the project tested biochar and feedstock with respect to PFAS and reported non-detect results in the outbound biochar at the testing limits used (parts-per-trillion levels). He said the project’s estimated greenhouse-gas benefit is approximately a 30,000-ton CO2-equivalent reduction per year (the company’s carbon intensity estimate) and a projected facility life of several decades.

Tristan Martinson of Ramsey-Washington Recycling & Energy (R&E) confirmed that Ramsey and Washington counties have signed a feedstock supply contract with Demcon and committed to supplying 65,000 tons of organics under that agreement; he said R&E’s collection program is rolling out and that additional counties may be approached to meet feedstock needs. County environmental staff emphasized the project fits priorities in the county’s solid-waste management plan that encourage organics diversion and technology to reduce landfilling.

Commissioners asked about the status of the Ramsey–Washington contract, CenterPoint Energy and Excel Energy purchases of RNG under Minnesota’s Natural Gas Innovation Act, truck counts on Highway 169, permitting timelines and costs related to added air-quality monitoring and control systems. Keegan said state permitting and contract conversations are in final phases and that utilities remain interested in buying the RNG under the state statute. No county action (vote) was taken at the meeting; the presentation was informational and staff invited further questions and follow-up with county and regional partners.

The board discussion included requests to continue outreach and to clarify traffic and feedstock flows; county staff and project representatives said neighborhood notices and public meetings had been held during the EAW and conditional-use review process.

The presentation materials and public-notification history were presented to the planning commission previously, and the Louisville Township board recommended approval at its January meeting. Scott County staff said formal county permit approvals were pending the board’s regular agenda process later in February.

The meeting did not adopt ordinances or issue permits; it was a staff presentation and public Q&A about the Demcon land-use application and associated state permits.