A numerical model, based on the Darcy law, was used to simulate the two-dimensional gas flow around a passive vent in a sanitary landfill. We follow Findikakis and Leckie [ASCE J. Environ. Eng. 105 (1979) 927] in modeling the biodegradation of the solid waste and assume the first-order biodegradation kinetics. The numerical results from the Fresh Kills landfill, New York, show that the well's ability in extracting the landfill gas by the passive vent decays quickly with the increase of the radial distance from the well. The influence radius of the well is generally less than 20 m. The effects from the final soil thickness, well depth, and other parameters on the gas flow are also discussed. (C) 2003 Elsevier Science B.V. All rights reserved.