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the oxygenation points were monitored daily, and weekly thereafter. Onsite air monitoring results indicate that hydrocarbon vapor migration had not been induced at the site. • On April 19, 2004, one soil boring was advanced and converted to an extraction well (EW-1). EW-1 was installed for the proposed NETTM system to remove SPH and mitigate hydrocarbon mass from the source area between AST 4131 and AST # 139. The well was purged and sampled with an interface probe. Free product was not detected in the well during installation; therefore the NETT'" system was not installed. EW-1 was monitored and sampled during all four quarters of 2005. Free product was not observed during the monitoring events; therefore, the NETTM system will not be installed. 3.4 Sources of Offsite Impacts Primary sources of petroleum hydrocarbon impacts to soil and groundwater were identified by a database search conducted by Environmental Data Resources (EDR) and a review of historical reports. A copy of the report entitled The EDR Radius Map Report, dated January 16, 2004, is presented in Appendix H. No leaking underground storage tank (LUST) sites were found within a '/z-mile radius of the site. Two LUST and 3 CORTESE sites were identified within a one-mile to two-mile radius of the site. These sites include: • DEUEL Vocational Institution, located at 23500 Kasson Road, Banta, California, at a distance of 3,660 feet southeast of the site; • Strong Property, located at 5157 Bus Loop 205 W, Banta, California, at a distance of 3,793 feet west- southwest of the site, and; • Moore Petroleum, located at 5491 F Street, Banta, California, at a distance of 7,339 feet west of the site. Releases of petroleum hydrocarbons have been identified at each of these sites. MtBE has been observed at a concentration of 2,000 parts per billion (ppb) and 5 ppb in groundwater beneath the Moore Petroleum and Strong Property sites, respectively. However, as all these sites are located a large distance away from the subject site, and in a direction away from groundwater flow observed at the site (north flowing), it appears that releases from these sites may not have potential to impact soil and groundwater beneath the site. 3.5 Potential Groundwater Receptors M As previously stated the Department of Water Resources file review indicated that no County or p y p ty City operated municipal water supply wells, which are typically screened in the Lower Tulare Aquifer, were observed within a one-mile radius of the site. A database search was conducted by EDR, on behalf of SECOR, to determine potential receptors of impacts from groundwater. A copy of the report entitled EDR GeoCheck Report, dated January 16, 2004, is presented in Appendix H. Seven United States Geological Survey (USGS) monitoring wells, and five private supply wells were identified within a one-mile radius of the site. None of the 12 wells identified as a result of the EDR database search are located downgradient of the site, given the predominantly north-northeastern groundwater flow direction. • BLASLAND, BOUCK &LEE,INC. 324106 engineers,scientists,economists 3-6 J\DOC 06\44634_001 61 022_Conceptual Site Model.doc