ACCOUNTING FOR WATER STORAGE EFFECTS IN LANDFILL LEACHATE MODELING

The water balance method is a widespread approach for estimating the v olumes of leachate that a landfill is likely to produce. Yet, this met hod does not always adequately reproduce observed patterns of landfill leachate production. This paper proposes a modified approach that tri es to account for the hydrologic behaviour of the waste in a manner wh ich is believed to be consistent with field measurements. The conceptu al model considers that a certain proportion of infiltration into the waste percolates rapidly through preferential pathways, while the rema ining infiltration is absorbed by the waste and released following a f irst-order kinetic relationship. A comparison between the proposed mod el and leachate volumes measured daily at two municipal solid waste la ndfills in France over a period of up to nine months suggests that the proposed approach is capable of reproducing observed behaviour. Moreo ver, the values attributed to the fitting parameters in order to obtai n a satisfactory match between measured and calculated data are consis tent with knowledge of the systems at hand and with the results of pre vious authors. While the proposed approach is not expected to improve substantially the long-term predictive capability of landfill leachate modelling, it is believed to be well suited for hydrologic performanc e diagnosis and for landfill leachate treatment system design.