Introduction

In 1997, the U.S. Environmental Protection Agency (USEPA) began a field investigation of the environmental conditions at a former waste-oil refinery in Westville, Ind. As part of this investigation, the U.S. Geological Survey (USGS) completed a study of geohydrology and water quality in the vicinity of the refinery. Previous investigations had detected contamination in soils at the site (ATEC Associates, Inc., 1985) and in off-site ground water (Dames and Moore, Inc., 1996). The site was listed as a Superfund site by USEPA in 1999.

The USGS study included installing monitoring wells, geophysical logging, aquifer testing, measuring ground-water and surface-water levels, measuring streamflow, and collecting water-quality samples. On the basis of a conceptualization of geohydrologic conditions developed from analysis of the collected data, the USGS constructed a ground-water-flow model for the study area. The calibrated model was used to investigate possible mechanisms of contaminant release, the effects of increased ground-water pumpage from nearby water-supply wells on contaminant distribution, and the capabil­ity of remediation by pumping from capture wells.