At what concentrations are nonmethane organic compounds typically found in uncontrolled landfill gas?
Concentrations of NMOC in uncontrolled landfill gas can vary depending on several factors, including the type of waste discarded in the landfill, the climate surrounding the landfill, and the physical properties of the individual organic compound. A default concentration of 595 parts per million by volume (ppmv) of NMOC is presented in EPA’s Compilation of Air Pollutant Emission Factors (AP-42). Of this total NMOC, 110 ppmv are considered HAP compounds, according to default concentrations in AP-42. Therefore, total uncontrolled concentrations of organic HAP at MSW landfills are typically less than 0.02 percent of the total landfill gas. The Standards of Performance for New Stationary Sources (NSPS) and National Emission Standards for Hazardous Air Pollutants (NESHAP) regulations require combustion of NMOC, a surrogate for organic HAP, at a destruction efficiency of 98 percent, or to an outlet concentration of 20 ppmv NMOC.
