Numerical Simulation of the Radius of Influence for Landfill Gas Wells

Abstract

In North America, most domestic waste produced is disposed in landfills. These sites generate leachate and gas, mainly CH4 and CO2, which are harmful for the environment if not properly controlled. The design of active landfill gas recovery systems is based in large part on the radius of influence of vertical pumping wells. This parameter is commonly estimated empirically. This study presents results of numerical simulations of the radius of influence of gas recovery wells for different site conditions. The simulations were performed with the TOUGH2‐LGM simulator. In the simulation scenarios, the radius of influence was defined in relation to several factors: the waste thickness, the generation rate of CH4 gas in the waste, and CH4 concentration in the recovered landfill gas. The results are presented in the form of general graphs that are not site‐specific. The adequacy of the results still needs to be validated against field measurements. On the basis of simulation results, a systematic approach is proposed for the design of landfill gas recovery systems, and this approach is illustrated with a hypothetic example. This approach should guide landfill managers and engineers in the design of landfill gas recovery systems. The simulations only considered cases where landfills are open to the atmosphere, which are representative of most operating conditions. The results thus do not apply to post‐closure conditions usually involving an impermeable cover built on top of the waste.

A Comprehensive Numerical Model Simulating Gas, Heat, and Moisture Transport in Sanitary Landfills and Methane Oxidation in Final Covers

“…Water percolating through the waste affects the degree of saturation and the distribution of leachate and gases in the pore spaces, thus lowering the effective permeability of porous media for both phases as well as the heat conductivity [27,49]. In addition, as the movement of the moisture is primarily in the downward direction, heat is carried in that direction.…”

Modeling Methane Migration and Oxidation in Landfill Cover Materials with TOUGH2-LGM

“…THOUGH2-LGM was successfully utilized in problems pertaining to production and collection of biogas, as well as gas migration through unsaturated porous or fractured media (Bour et al 2003;Nastev et al 2003;Vigneault et al 2004).…”

A logistic model for the prediction of the influence of water on the solid waste methanization in landfills

“…In the first type, biological processes are reduced to the hydrolysis of the solid substrate, which is the limiting reaction step. The substrate degradation rate is described by a simple first order substrate related kinetic (Arigala et al, 1995;Findikakis and Leckie, 1979;Hashemi et al, 2002;Nastev et al, 2001;Vigneault et al, 2004). No water dependency for the hydrolysis reaction is introduced.…”