Milwaukee Metropolitan Sewerage District approves deal to buy landfill gas from Waste Management

Landfill gas from the Metro landfill in Franklin will begin flowing to the Jones Island sewage treatment plant in the summer of 2019, as part of a revised agreement approved Monday by the Milwaukee Metropolitan Sewerage District's commission.

Waste Management of Wisconsin will be the district's second supplier of landfill gas — a lower cost fuel than natural gas — to power the plant and dry Milorganite fertilizer, after connections are completed in two years.

Metro is across S. 124th St. from the district's first supplier, Advanced Disposal Service's Emerald Park landfill in Muskego. The landfill is north of County Line Road.

Contaminants will be removed from Metro's landfill gas before it is piped to Emerald Park and blended with the fuel supply there, officials said. Concentrations of water vapor, hydrogen sulfide and silicon particles in the gas must be reduced before the fuel is burned at Jones Island.

MMSD will be responsible for designing, constructing and operating the landfill gas treatment plant, compressors and meters to be built on Metro property, under the agreement. Cost of the plant is estimated at $11 million, officials said.

Waste Management will construct a pipeline connection to Emerald Park and maintain its landfill gas extraction system at Metro, as part of the deal.

The agreement will save district ratepayers up to $10 million over the 20-year contract, according to MMSD Controller and Treasurer Mark Kaminski.

MMSD will pay Waste Management 36% of the market price for natural gas based on energy content, not volume, under terms of the revised agreement.

Landfill gas is released during decomposition of garbage by bacteria. About 50% to 55% of the gas is methane.

Burning landfill gas offsets the use of natural gas and other nonrenewable resources and improves air quality by reducing emissions of hazardous pollutants, according to the U.S. Environmental Protection Agency.

The fuel is burned in three turbines on Jones Island to generate electricity for the sewage treatment plant. Waste heat from the turbines has been used in drying of sewage sludge in the production of Milorganite fertilizer.

MMSD also plans to begin converting burners inside large rotary sludge dryers at the Milorganite factory so they will be able to burn both natural gas and landfill gas when the additional flow arrives from the Metro landfill.

No decision has been made on how many of the 10 dryers will be converted, officials said. Cost of switching each burner is estimated between $700,000 and $900,000, depending on the number that is done, Kaminski said.

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The price paid by MMSD would not fall below $1 per dekatherm during the 20-year term of the deal. One dekatherm is equal to 1 million British thermal units, or Btu.

The district agrees to buy a minimum of 300,000 dekatherms from the Metro landfill in the first year and a minimum of 430,000 dekatherms in subsequent years.

In return, Waste Management will stop burning the gas in turbines at its own electrical power plant on the Metro property. Since 1985, the company has sold the power to We Energies.

The agreement is contingent on Waste Management receiving state Department of Natural Resources approval for a 9 million cubic yard expansion of the Metro landfill.

Lack of a reliable flow of landfill gas was an issue for the district's first supplier, Emerald Park. Advanced Disposal has delivered less of the fuel than promised each year since the start of that contract in 2014.

Advanced Disposal estimates it will deliver 381,000 dekatherms this year. At its current rate of supply, the company will deliver around 342,000 dekatherms by the end of the year, according to Kaminski.