Expansion is part of a short-term solution to Twin Cities metro’s growing waste problem
The Minnesota Pollution Control Agency (MPCA) has released its environmental assessment worksheet (EAW) and draft air permit for the proposed vertical expansion of the Pine Bend Landfill in Dakota County. BFI Waste Systems of North America LLC, owned by Republic Services, is proposing to raise the height of the landfill by 85 feet, increasing its capacity by approximately 8,185,000 cubic yards — or 2,398,746 tons — and extending its life through 2045.
The Pine Bend Landfill accepts mixed municipal waste from the seven-county metropolitan area, which generates 3.3 million tons of garbage annually and sent 30 percent more waste to landfills last year than in previous years. This project is part of the short-term solution to expand four area landfills to help address the growing problem and ensure continued safe and proper management of waste materials.
The EAW and air permit, in addition to the solid waste permit that will be released at a later date, all work together to assess the potential for significant environmental effects and put measures in place to protect the environment and nearby residents from pollution generated by the landfill.
Environmental assessment worksheet
The EAW reviewed potential impacts to air, local geology, soils, groundwater, surface water, and other potential environmental impacts. Some key findings include:
- The project will not absorb groundwater and is not located within protection areas for wells or drinking water supplies. The facility has an existing groundwater monitoring network in place and would continue to monitor groundwater quality.
- Leachate generated will be collected by systems that are already constructed and in place.
- An existing liner system is in place over certain sections of the landfill. A new composite liner is planned for future installation.
- New well heads are proposed to capture and transport methane gas via pipeline to an adjacent recovered natural gas facility.
- Sampling for perfluoroalkyl substances (PFAS) at 22 monitoring wells is required in the landfill’s solid waste permit. Most recent sampling shows levels at or above permit levels at 12 wells and two springs. Testing over time shows a decrease of PFAS at some well locations and an increase at others.
Air emissions permit
The MPCA is updating and reissuing the landfill’s air emissions permit, which includes three minor amendments.
Emissions generated from the larger landfill, as well as the facility’s renewable natural gas plant and diesel-fired tipper, remain below permit thresholds. Emissions of volatile organic compounds (VOCs) from the vertical expansion will increase by 0.25 tons/year. Emissions from the installation of the renewable natural gas plant decreased for most pollutants but increased by 7.4 tons/year for VOCs. The diesel-fired tipper has emissions low enough to be classified as an insignificant source.
The renewable gas plant began operating in 2022 and helps reduce greenhouse gas emissions that contribute to climate change. The plant captures biogas generated from decomposing waste — which is mostly methane, a potent greenhouse gas — and transforms it into renewable natural gas used by Xcel Energy. It is the first such plant in Minnesota.
The air permit requires the renewable natural gas plant to install and maintain controls to reduce emissions:
- A thermal oxidizer will combust gases that are either removed as waste during processing or do not meet pipeline quality standards.
- An open flare will combust landfill gas that cannot be accommodated by the renewable gas plant and/or pipeline.
The Pine Bend Landfill has been developed in phases since 1971. Construction for this phase is anticipated to begin in early 2024.
Community meeting to discuss the expansion
The public is encouraged to comment on the EAW and air permit during the 45-day public notice period, starting October 31, 2023. The MPCA will host a public meeting for community members on November 30, 5:30-7 p.m., at Woodcrest Church (525 Cliff Road, Eagan, MN 55123), with an open house and brief presentation on the draft permits and EAW.
The public can review the draft EAW and air permit and submit public comments by visiting www.pca.state.mn.us/publiccomments or by mail to:
EAW: Minnesota Pollution Control Agency
c/o Megen Dvorak Kabele
520 Lafayette Road
St. Paul, MN 55155
Air permit: Minnesota Pollution Control Agency
c/o Joy Wiecks
520 Lafayette Road
St. Paul, MN 55155