Temporal Geophysical Investigations of the FT-2- Plume at the Wurtsmith Air Force Base, Oscoda, Michigan

Abstract

The decommissioned Wurtsmith Air Force Base former Fire Training Cell (FT-02) facility has been the focus of several geophysical investigations. After several decades of fire training exercises, significant amounts of hydrocarbons and some solvents seeped into the subsurface contaminating the vadose and saturated zones in the source area. Groundwater geochemistry studies defined a contaminant plume that was approximately 125 m wide and >300 m long. The boundary of the plume was further defined by using GPR, SP, and resistivity techniques. The source of the geophysical anomalies was attributed to biogeochemical modifications of the contaminated zone resulting from intrinsic bioremediation. In 2007, another integrated geophysical study of the site was conducted. GPR, SP, and electrical resistivity surveys were conducted with expectations of achieving similar results as the past investigations. However, there was a marked decrease in geophysical response from all of our geophysical techniques. The GPR anomaly has migrated deeper into the subsurface, the positive SP response was significantly attenuated, and the conductive resistivity anomaly has been replaced by background resistivity values. Also, six Geoprobe cores at three different locations were collected in order to conduct laboratory microbial counts and IP measurements. We attribute the attenuation of the observed geophysical anomalies to ongoing soil vapor extraction initiated in 2001. Significant removal of the contaminant mass by the vapor extraction system altered the subsurface biogeochemical conditions and these changes were documented by the 2007 geophysical data. The results of this study show that the attenuation of the contaminant plume is detectable with geophysical methods.

Meeting Name

21st Symposium on the Application of Geophysics to Engineering and Environmental Problems (2008: Apr. 6-10, Philadelphia, PA)

Department(s)

Geosciences and Geological and Petroleum Engineering

Keywords and Phrases

Air Force Base; Biogeochemical Conditions; Contaminant Plume; Electrical Resistivity; Fire Training; Geophysical Data; Geophysical Methods; Geophysical Techniques; Michigan; Microbial Count; Resistivity Values; Saturated Zone; Soil Vapor Extraction; Source Area; Vapor Extraction; Biogeochemistry; Bioremediation; Electric Conductivity; Geophysics; Groundwater Geochemistry; Hydrocarbons; Soil Conservation; Vapors; Geophysical Prospecting

Geographic Coverage

Michigan

International Standard Book Number (ISBN)

978-1605603001

International Standard Serial Number (ISSN)

1554-8015

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2008 Environmental and Engineering Geophysical Society (EEGS), All rights reserved.

Publication Date

01 Apr 2008

Link to Full Text

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