Hydro-Geophysical Investigation of Contaminant Distribution at a Closed Landfill in Southwestern Ontario, Canada

Jianwen Yang, Siddharth Dilip Joshi

1College of Earth Sciences, Guilin University of Technology, Guilin, China 2Department of Earth and Environmental Sciences, University of Windsor, Windsor, Canada.
Conestoga-Rovers & Associates, Waterloo, Canada.

DOI: 10.4236/gep.2014.23002                

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.

Keywords

Geophysical Mapping, Hydrological Modeling, Landfill Leachate, Southwestern Ontario, Canada

Conflicts of Interest

The authors declare no conflicts of interest.

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