Mapping Contamination Potential by Combining 3-D Geologic Analysis and Groundwater Hydrology—an Application of GIS for Preemptive Protection of Groundwater Underlying Oil Production and Processing Facilities

James M. Rine¹, John M. Shafer², Elzbieta Covington², William Domoracki², Michael Waddell², and Richard C. Berg^3
1 OMNI Laboratories, Inc, Houston, TX
² Earth Sciences & Resources Institute, Columbia, SC
³ Illinois State Geological Survey, Champaign, IL

If groundwater resources underlying areas of petroleum production and processing are “preemptively“ protected, the high cost of remediation can be avoided. A methodology to preemptively protect groundwater was tested in a multi-year hydrogeologic study at the Marine Corps Air Station in Beaufort, SC (MCAS-Beaufort), a facility whose numerous fighter jets insure massive use, transport, and storage of petroleum products. The study focus was on determination of groundwater contamination potential throughout the 22 km2 airbase using a GIS-based stack-unit mapping methodology. The contamination potential assessment at MCAS-Beaufort was completed based on integration of historic hydrogeology data, new high-resolution reflection seismic profiles, and core analysis from over 40 new boreholes and wells. Six hydrogeologic units were mapped and tops from these units were “machine-subtracted” to create isopach maps. The hydrogeologic units were then ranked according to their vertical permeability and relative proximity to the ground surface with fine-grained units being ranked as more important than coarse-grained units because the former impedes the flow of contaminants more so than the latter. Addition of hydrologic models, based on multi-seasonal water level monitoring, combined with the geologic model showed, however, that even in areas overlying low permeability strata, contaminants released on the ground surface could reach critical underlying aquifers within tens of years due to rapid groundwater flow. Consequently, this study demonstrates that both geologic mapping and groundwater modeling are necessary to accurately delineate areas of high and low aquifer sensitivity, thus providing a preemptive way to avoid costly groundwater contamination and cleanup.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005