Lateral gas transport in soil adjacent to an old landfill: factors governing gas migration

Field experiments investigating lateral gas transport in soil adjacent to a n old landfill in Denmark during a one-year period were conducted. A signif icant seasonal variation, with low concentrations of methane and high conce ntrations of carbon dioxide in the summer, caused by methane oxidation was observed. There was a good correlation between pressure above the barometri c pressure and the methane concentration in the soil, indicating that advec tive flow was the controlling process. This was confirmed by calculations. Diurnal measurement during a drop in barometric pressure showed that latera l migration of landfill gas was a very dynamic system and the concentration s of LFG at a specific place and depth changed dramatically within a very s hort time. The experiments showed that change in barometric pressure was an important factor affecting gas migration at the Skellingsted landfill in D enmark.