The Use of 3D Seismic Imaging in Making Groundwater Management Decisions At Hazardous Waste Sites

Abstract: Three-dimensional (3D) acoustic imaging is a highly developed technology that has produced a detailed image of the subsurface, at over 30 hazardous waste sites. 3D imaging has been used to provide the density of data necessary to analyze the pathways for fluid transport, whether in free phase or as a dissolved plume. This information has then been used to optimally locate control or monitor points. Evaluation of chemical sampling while drilling has been combined with the seismic data to address whether the plume can be contained or remediated. In 1994 the first 3D seismic survey over a hazardous waste site was performed at Naval Air Station North Island in California. The 3D seismic information, followed by confirmatory drilling, significantly changed the site conceptual model. The seismic image saved time and costs for characterization and remediation. A seismic survey at a NASA site and confirmatory drilling showed that free product was not present and that natural attenuation could be used. At Edwards AFB in California, there was concern that contaminants could migrate off base. The seismic image demonstrated that this was unlikely. The technology can be used to help determine if groundwater problems exist and for more rapid remediation when required. METHODOLOG