oa Impact of Soil Vapor Extraction On SIP Measurements

The Wurtsmith Air force Base (WAFB) and Carson City refinery sites have long been known as locations exhibiting active bioremediation of hydrocarbons. the geophysical response over the hydrocarbon contaminants has been well documented by numerous authors. Recently the WAFB site has undergone extensive remediation (soil vapor extraction) efforts to remove the contaminant mass above the water table. the WAFB data and the Carson City data have been compared to see the effect that remediation efforts have had on the geophysical signatures of the sites. in both studies, sediment cores were collected from locations inside and outside of the contaminant plumes: one outside the plume and two inside. the contaminated cores were collected at a location proximal to the contaminant source and distant from the source to determine the effect that distance plays on the results. Spectral Induced polarization measurements (0.1Hz – 10kHz) were then taken on the cores to develop a SIP depth profile of the contaminant plumes. When the WAFB and Carson City cores are compared, the Carson City data shows a clear increase in real and imaginary conductivity components when inside the contaminant mass while the WAFB data does not show any significant response. This lack of response at the WAFB site is due to removal of the contaminant body and carbon source for the microbial populations that were once at the site. the contaminant body and microbial activity is still active at the Carson City location and exhibits a strong SIP response.