The Metropolitan Council is breaking ground Wednesday on a fourth wastewater sludge incinerator at its Metro Plant in St. Paul, a $210 million project meant to keep pace with a region expected to add 350,000 more residents by 2050. The new unit will boost the plant's solids-processing capacity by about 25% and is scheduled for installation by the end of 2027.
The Metro Plant, which sits along Childs Road and dates back to 1938, is the largest wastewater treatment facility in Minnesota, according to Pioneer Press. It treats roughly 180 million gallons of wastewater daily, processes about 850 wet tons of solids each day, and handles an estimated 70% of all wastewater generated across the Twin Cities. The plant serves 66 communities directly and 73 communities for solids processing, discharging treated water into the Mississippi River.
Met Council Chair Robin Hutcheson and Environmental Services General Manager Leisa Thompson are among the officials expected to speak at Wednesday's ceremony, which is open to scheduled attendees and speakers but not the general public, per the same report. Ramsey County Commissioner Kelly Miller and Met Council member Gail Cederberg, who chairs the council's environment committee, are also tied to the project's oversight. The region's broader sewer network, which the article notes is not funded by property taxes but by user fees from utility bills, includes 600 miles of regional sanitary sewers owned by the Met Council that connect to another 5,000 miles of municipal sewer lines, collecting about 250 million gallons of wastewater daily from 109 metro-area communities.
A Plan Years in the Making
The fourth incinerator has been in the works since at least 2015, and the Minnesota Pollution Control Agency took public comment on an environmental assessment worksheet and an air emissions permit for the project back in 2023, the outlet reported. Once the new unit is operating, the Met Council's existing three incinerators are slated for rehabilitation, with that work expected to wrap by the end of 2030.
The decision to add another fluidized bed incinerator rather than pursue alternatives like land application or composting rests on economics as much as capacity. According to a formal facility planning analysis from the Metropolitan Council, adding a fourth incinerator was found to be 50% less expensive to build, operate, and maintain over time than every other solids treatment option evaluated. The council manages an ongoing regional capital improvement program that averages roughly $140 million a year, making the incinerator one of its larger single investments.
Weighing Emissions and Environmental Tradeoffs
Environmental comparisons factored into the decision as well. Lifecycle evaluations presented by the Metropolitan Council in December 2015 found that fluidized bed incineration at the Metro Plant produces greenhouse gas emissions roughly equivalent to 5,000 passenger vehicles per year, compared to about 11,000 vehicles' worth for anaerobic digestion and drying alternatives — a notable difference set against a Twin Cities transportation sector that accounts for emissions equivalent to roughly 4 million cars. During technical review of the facility plan, Met Council project engineers also reported that choosing a fourth incinerator over land application would cut potential facility emissions by 2.5 tons per year compared with the initial project design, according to Community Reporter. The facility remains bound by federal EPA standards regardless of which technology is chosen.
The incineration process itself generates roughly 38 tons of ash daily, which is currently landfilled while University of Minnesota researchers study whether it could serve as an agricultural phosphorus fertilizer for corn and soybean crops, per research highlighted by Access Water. Phosphorus is a finite nutrient currently mined globally, giving the research added significance beyond waste disposal. Separately, the plant's fluidized bed incinerators use waste-heat boiler systems that capture thermal energy from sludge combustion to generate steam and electricity, offsetting some of the facility's external energy costs, according to the American Council for an Energy-Efficient Economy.
A History Tied to Federal Enforcement and a Nearby Superfund Site
The Met Council's shift to fluidized bed incineration technology began in the early 2000s, replacing 1960s-era multiple hearth furnaces after a 1999 federal enforcement lawsuit, United States v. Metropolitan Council. That settlement prompted a $200 million overhaul of the original fluid bed incinerator system, according to Met Council records.
The plant's waste-handling history also connects to a nearby cleanup effort. Between 1977 and 1985, Metropolitan Council Environmental Services deposited sewage sludge incinerator ash across 31 acres at the adjacent Pig's Eye Dump, a site added to Minnesota's Superfund list in 1989 that received a comprehensive state cleanup plan finalized in January of this year, according to the Minnesota Pollution Control Agency. Initial remediation phases there removed lead-contaminated surface soil and hazardous battery drums.
Local advocacy groups, including the West Side Community Organization and the Sierra Club, raised environmental justice concerns in 2022 about cumulative industrial air pollution in nearby St. Paul neighborhoods and called for expanded air quality monitoring, according to the Sierra Club. St. Paul's East Side and West Side have historically carried a concentration of industrial processing infrastructure, a pattern residents point to in pushing for stricter cumulative pollution monitoring near the Superfund-listed dump site.
Part of a National Shift Away From Land Application
The St. Paul project also reflects a broader national trend. Clean water research published in 2024 and 2025 points to high-temperature sewage sludge incineration as a primary method for the thermal destruction of PFAS, or forever chemicals, as land application of biosolids faces tightening regulations nationwide, according to the Water Environment Federation. Several states have restricted land application of wastewater biosolids over groundwater contamination concerns, a shift that has pushed incineration further into the spotlight as a containment method.
Metropolitan Council Environmental Services serves 110 municipal customers and roughly 800 industrial permittees across the seven-county metro region, financing projects like the new incinerator through user fees and low-interest loans from the Minnesota Public Facilities Authority rather than local property tax levies, according to the National Association of Clean Water Agencies. Minnesota Pollution Control Agency Assistant Commissioner for Air and Climate Frank Kohlasch is also named in connection with the project's state-level air permitting review. With the region's population growth showing no signs of slowing, the Met Council is betting that a fourth incinerator, alongside rehabilitation of its three existing units by 2030, will keep the Metro Plant ahead of demand for years to come.
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