Accounting for water storage effects in landfill leachate modelling

Abstract

The water balance method is a widespread approach for esti mating the volumes of leachate that a landfill is likely to pro duce. Yet, this method does not always adequately reproduce observed patterns of landfill leachate production. This paper proposes a modified approach that tries to account for the hydrologic behaviour of the waste in a manner which is believed to be consistent with field measurements. The con ceptual model considers that a certain proportion of infiltra tion into the waste percolates rapidly through preferential pathways, while the remaining infiltration is absorbed by the waste and released following a first-order kinetic relationship. A comparison between the proposed model and leachate vol umes measured daily at two municipal solid waste landfills in France over a period of up to nine months suggests that the proposed approach is capable of reproducing observed behav iour. Moreover, the values attributed to the fitting parameters in order to obtain a satisfactory match between measured and calculated data are consistent with knowledge of the systems at hand and with the results of previous authors. While the proposed approach is not expected to improve substantially the long-term predictive capability of landfill leachate mod elling, it is believed to be well suited for hydrologic perfor mance diagnosis and for landfill leachate treatment system design.