A hydrogeological and geophysical assessment of a contaminant plume emanating from the Terra Nova Regional Waste Disposal Site

Abstract

A 16 year study, started in 1977, was undertaken to assess a subsurface contaminant plume emanating from the Terra Nova Regional Waste Disposal Site in Newfoundland. Eleven (11) monitoring wells, installed at the waste site shortly after the first cell was dug, were sampled regularly to detect changes in background groundwater concentrations of selected chemical parameters. Four (4) surface water locations were also monitored to detect changes in surface water chemistry. A geophysical study was undertaken to provide data on the location of the contaminant plume and to derive useful information on sub surface conditions. A geotechnical soil description including the hydraulic properties of the overburden soils was obtained using several in situ and laboratory techniques. Chemical analysis of the leachate plume was obtained via monitoring well water sampling. -- Groundwater sampling and the geophysical survey show that a leachate plume exists down stream of the waste site, but remains within the confines of the site boundaries. Electromagnetic (EM) surveys provide evidence that the leachate has preferentially flowed along bedrock channels. The geochemical sampling results exhibit variability with time suggesting preferential flow paths rather than a continuous uniform plume. Ion concentrations of surface water sites showed that water quality concentrations were below the Canadian Water Quality Guidelines for drinking water.