Hazardous Pollutants in Class II Landfills

Class II landfills accept nontoxic municipal trash. Their gaseous emissions were originally assumed to be relatively free of hazardous substances. However, one Class II site in Southern California was found to be emitting enough vinyl chloride to exceed the California Air Quality Standard of 10 ppb for a 24-hour average in surrounding neighborhood. This paper presents a summary of the results of the analysis of landfill gas from over 20 additional Class II landfills. Ambient air surveys were conducted around five of the landfills. About 90 percent of the landfills contained measurable amounts of vinyl chloride and/or benzene. The concentrations exceeded 1 ppm in about half of the sites studied. Vinyl chloride is produced in situ by the action of bacteria on chlorinated solvents, and can be found in landfills that have been closed for over 30 years. The relative amounts of methane and vinyl chloride vary so much within a single landfill that methane measurements cannot be used as a surrogate for vinyl chloride