Abstract
This paper presents a hydro-geophysical investigation into the landfill leachate distribution and subsurface geology at a closed site in southwestern Ontario, Canada, using geophysical mapping and hydrological modeling approaches. Conductivity mapping was first conducted over the study site using a frequency-domain EM terrain conductivity meter, revealing an anomalous high-con- ductivity zone of about 200 m (S-N) × 80 m (W-E) at the western half of the site. The DC resistivity survey was then carried out at this anomalous zone with eight S-N profiles and three W-E profiles measuring 200m in length using a Wenner-α configuration. Our resistivity survey results indicate that the landfill leachate travels mainly south-east wards over the upper aquifer, with a minor vertical component into the upper weathered portion of the silt/sand aquitard at some locations. No contamination seems to exist in the lower sand aquifer. The geophysical results were later used to develop two conceptualized models for hydrological modeling. Our numerical results predict the leachate distribution at the study site in the future, confirming that the contaminant will occupy the entire upper aquifer and the most of the aquitard in a time of 1000 years, and that the barrier of the aquitard will protect the lower sand aquifer from the leachate pollution. These findings are critical in evaluating the current leachate conditions and the existing compliance monitoring plan for potential implementation at this study site and other sites in elsewhere.
Highlights
Due to an increase in the commercial and industrial growth rate in countries around the world, proper waste management and monitoring techniques have to be developed to anticipate and avert undesirable impacts to the environment (Farquhar, 1989; Soupios et al 2007; Renou et al 2008).To avoid adverse socio-economical and environmental impacts of contamination from landfills in future, government organizations have passed stringent laws which ensure that proper waste disposal/monitoring protocol are followed by individuals and other organizations
Due to the ever-increasing rate of waste generation, governments are pressured to construct more landfills, which primarily rely on setting up multiple layers of expensive impermeable geomembranes and liners to contain the effluents within the landfill and completely disregard the geological and hydrogeological parameters of the area during the planning stages (Gray et al 1974; Tchobanoglous et al 1993; Cossu, 1994; Cossu, 1995)
The problem with geo-synthetic membranes is that they are an unproven technology which has only been used for the past 30 years. Their performance beyond this time remains uncertain and this should be a cause of worry for all those nations that adopt this technology (Allen, 2001)
Summary
Due to an increase in the commercial and industrial growth rate in countries around the world, proper waste management and monitoring techniques have to be developed to anticipate and avert undesirable impacts to the environment (Farquhar, 1989; Soupios et al 2007; Renou et al 2008).To avoid adverse socio-economical and environmental impacts of contamination from landfills in future, government organizations have passed stringent laws which ensure that proper waste disposal/monitoring protocol are followed by individuals and other organizations. Due to the ever-increasing rate of waste generation, governments are pressured to construct more landfills, which primarily rely on setting up multiple layers of expensive impermeable geomembranes and liners to contain the effluents within the landfill and completely disregard the geological and hydrogeological parameters of the area during the planning stages (Gray et al 1974; Tchobanoglous et al 1993; Cossu, 1994; Cossu, 1995). This is an expedient temporary solution for the problem but uneconomical for developing countries. Studies have proven that such geo-synthetic membranes have faltered under the stress of waste, temperature fluctuations due to exothermic reactions of waste degradation, type of waste buried and age-related inconsistencies (Rollin et al 1991; Thomas and Woods-DeSchepper, 1993; Cazzuffi et al 1995; Duquennoi et al 1995; Surmann et al 1995; Thomas et al 1995; Thomas and Kolbasuk, 1995)
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