TITLE:
Hydro-Geophysical Investigation of Contaminant Distribution at a Closed Landfill in Southwestern Ontario, Canada
AUTHORS:
Jianwen Yang, Siddharth Dilip Joshi
KEYWORDS:
Geophysical Mapping, Hydrological Modeling, Landfill Leachate, Southwestern Ontario, Canada
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.2 No.3,
June
12,
2014
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.