ABSTRACT
The UCG process has the potential to cause significant hydrologic and geomechanical changes in the area surrounding the coal seam. Estimation of the environmental threat posed to groundwater resources as a result of UCG involves consideration of several elements, including (Burton): Enhanced vertical hydraulic conductivity of the rock matrix above the burn chamber as a result of collapse and fracturing; Thermally-driven upward flow of groundwater resulting from in situ burning of coal; Generation of the contaminants within the burn chamber; Potential for bioattenuation of contaminant compounds that migrate into potable water aquifers. To directly address the issue of environmental risk posed to groundwater, the parameter spaces associated with these relevant processes need to be explored to identify, in a quantitative context, those scenarios are most favorable for UCG and which are least favorable. Output from such an effort will facilitate comparison of risk scenarios.
