Landfills case study: Space heating with LFG: Small project-big savings

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Courtesy of Waste Advantage Magazine

On a typical January morning in Minnesota, a landfill operator is working on the compactor’s transmission. Despite the four inches of snow on the ground, he opens the garage doors in the maintenance building to let out some of the excess heat. Unlike previous winters, this year the operator can afford to crank up the heat in the building while working on equipment because the heat is being fueled by a renewable energy source created right on site.

The Crow Wing County Landfill located in northern Minnesota recently installed a boiler fueled by landfill gas (LFG) to provide heat to its two maintenance buildings. With this investment, the landfill has been able to significantly reduce its heating costs and its carbon emissions.

A Small Site with Big Hopes

The landfill serves the county’s nearly 60,000 yearround residents and, during the spring and summer, it serves twice that population as vacationers visit the many resorts dotting the lakes of the county. The landfill provides disposal options for nearly all kinds of waste. The landfill’s current disposal area is a four cell, 22.5 acre area. It began operation in 1991 under the U.S. Resource Conservation and Recovery Act, Subtitle D rules, and was the first in the state of Minnesota to do so. In addition to the active areas of the landfill, there is also an unlined 28-acre landfill that was closed in 1992.

The county constructed Cell 1 along with two leachate treatment ponds (700,000 gallons each) in 1991. In 1995, it added Cell II and a third treatment pond with capacity of 680,000 gallons. Disposal occurred in Cells I and II for 10 years before the landfill built Cell III in 2001. Then in summer 2007, it constructed Cell IV and a 2.5 million gallon leachate pond with the eight-acre Cell IV beginning waste filling in 2008.

Crow Wing County has worked hard to construct and operate a facility that is able to manage and maintain environmental liabilities on site. In 1994, it installed a land application system on the closed landfill. Using the treatment capabilities of the leachate ponds, the landfill reduced offsite hauling of leachate by spraying treated leachate over the 11- acre spray field. However, as the facility grew, the need for more leachate storage, treatment and disposal increased.

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