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• i <br /> 20 December 2000 <br /> AGE-NC Project No. 95-0100 <br /> Page 2 of 8 <br /> Data collected at the site during the investigation of the former UST site indicated that hydrocarbon- <br /> impacted soil is present in the vadose zone from approximate depths of 5 to 35 feet bsg. Therefore, <br /> only hydrocarbon-impacted soil remediation alternatives were explored during feasibility studies. <br /> The results of the soil remediation feasibility studies are detailed in the Corrective Action Plan <br /> prepared by AGE, dated 29 November 1995. <br /> AGE installed and operated a thermal oxidation SVE unit at the site. Soil gas/vapor samples indicted <br /> a decrease of overall concentrations of TPH-g and BTEX over a six month operation. As a result <br /> of the declining concentrations in the soil/vapor extraction, soil samples were collected in January <br /> 1999 to confirm the removal of the hydrocarbons. Additionally one `grab' ground water sample was <br /> collected at the request of the PHS-EHD. The `grab' ground water samples contained residual BTEX <br /> and MTBE. <br /> Three ground water monitoring wells were installed in late 1999 and these wells, along with the three <br /> domestic water supply wells, have been sampled a total of three times. Ground water samples <br /> contained MTBE at concentrations as high as 1,800 micrograms per liter, specifically in the area of <br /> the former UST dispenser area. Lower concentrations of MTBE have been continually detected <br /> approximately 130 feet northwest of the former USTs. <br /> 3.0. SCOPE OF WORK <br /> Based on the analytical results of the ground water samples, the release of petroleum hydrocarbon <br /> compounds at the site has impacted ground water. AGE proposes to established ground water <br /> monitoring wells to evaluate the lateral extent of MTBE impact to ground water beyond the current <br /> well network. The investigation of the extent of the MTBE contamination at the site will consist of <br /> the following tasks: <br /> • Permitting and pre-field work activities; <br /> • Soil sample collection and analysis; <br /> • Monitoring well installation and development; <br /> • Ground water sample collection and analysis and <br /> • Report preparation. <br />