Measurements of Soil Gas and Atmospheric Methane Content on One Active and Two Inactive Landfills in Wood County, Ohio

Abstract

Methane concentrations (by volume) in soil gas and in the atmosphere were measured over several days in February and March of 1996, at several on-site stations on three solid waste landfills in Wood County, Ohio. The lower detection limit for methane in soil gas was 0.2 percent (2,000 ppm) and in the atmosphere was 0.1 percent (1,000 ppm). The oldest site, Asman9s Landfill (1962–1973), contained no atmospheric methane at or above the detection limit and had the second highest methane content in soil gas of the three landfills. Wales Road Landfill (1950s–1994) had the highest soil gas methane concentration, as high as 96 percent (960,000 ppm) methane, and had some detectible atmospheric methane (as much as 4,000 ppm) on two occasions over one station. Wood County Landfill (1972-present) had the lowest average soil gas methane content of the three landfills, but the highest atmospheric methane (as much as 8,000 ppm), although all of the methane concentrations at or above the detection limit were measured near four passive vents in the landfill, where soil gas methane content was below the detection limit. Methane concentration in soil gas increased with increasing barometric pressure, but the relationship between atmospheric methane concentration and barometric pressure appears to be more complex, from a few data points for atmospheric methane concentration above the Wood County and Wales Road Landfills. The Wood County Landfill would make an excellent test site for a methane imaging experiment that employs airborne multispectral remote sensing.