Landfill Leachate Migration Through Shallow Unconfined Aquifers

Abstract

We model the transport of a simply reactive contaminant through a landfill and initially pure, underlying, shallow, one‐dimensional unconfined aquifer with a plane, sloping bottom under steady hydraulic conditions in the assumed absence of dispersion and downgradient dilution. The user population and a presumedly constant contaminant loading factor determine the pollution input to the groundwater system, and we model the near field response as a single linear reservoir whose output comprises the far field source term at the downgradient edge of the landfill. The far field analysis yields a method of characteristics solution valid in the vicinity of the source location with frame speeds modified by recharge, head loss, bottom slope, and linear adsorption, and concentrations reflecting first‐order reaction kinetics. We calibrate and test the near and far field models against conservative chloride and first‐order reactive bicarbonate data at the Babylon, New York landfill with accurate and physically plausible results.