TWO UNCONVENTIONAL SOURCES OF METHANE IN NORTH DAKOTA

Municipal waste has been buried at the current Fargo Municipal Landfill since 1980. The geologic setting consists of glaciolacustrine silts and clays, deposited in an offshore depositional environment of Glacial Lake Agassiz, and a shallow water table. The facility consists of unlined and lined waste placement areas. Approximately 1.7 million tons of waste has been placed within the lined landfill facility. A gas collection system was installed at the landfill in 2001 and currently removes landfill gas at a rate of more than 400 cubic feet per minute. Since construction over 300 million cubic feet of landfill gas has been used, as an alternative fuel source, by local industry in West Fargo. Landfill gas has also been observed in landfills near Minot, Harvey, Williston, Grand Forks, and Hillsboro.

In 1995, the North Dakota Geological Survey investigated sodium sulfate deposits beneath 15 playa lakes in northwestern North Dakota. The Holocene deposits beneath these lakes are up to 80 feet thick and consist primarily of black, organic-rich clays and crystalline layers of sodium sulfate. It was discovered during the investigation that these deposits are gas-rich. Although not analyzed, this gas was assumed to be a mixture of methane and hydrogen sulfide, strong odors suggested the presence of the latter. During the drilling program, gas bubbled continuously in the borehole and pockets of gas were encountered immediately beneath the salt layers. Gas was also observed escaping from vents on the bottom of Miller Lake in Divide County.