Methane Emissions at Nine Landfill Sites in the Northeastern United States

Abstract

Methane emissions were measured at nine U.S. landfill sites using chamber and/or tracer flux techniques. These flux measurement methodologies were compared at two sites, and excellent agreement (<10% difference) was observed. Total methane emissions ranged from 540 to 30 100 L min-1. Expressed on an area basis, methane fluxes ranged from a low of 9.1 g of CH4 m-2 d-1 at a closed 20-ha site with active gas recovery to 130 g of CH4 m-2 d-1 at a 23-ha active site with no gas recovery. Methane emission factors [in units of m3 of CH4 min-1 (106 m3 waste-in-place)-1] were calculated for seven of the nine sites. The two sites with no active gas recovery exhibited the highest emission factors of 4.8 and 5.1. Values were significantly lower at three sites with partial gas recovery, ranging from 1.6 to 3.7. At the two closed sites with active gas recovery, emission factors were much lower still (0.4 and 1.1). It is evident that even partial gas recovery at active landfill sites can significantly reduce methane emissions, and gas recovery at closed, covered sites reduces methane emissions to the atmosphere by as much as a factor of 10.