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' Rajappan&Meyer • . Date:3/3/99 Arch Road/Highway 99 Page: 3 ' 2.2 Geophysical Survey A geophysical survey was conducted at the site to determine if USTs remained at the site of the former gas station. The survey entailed vertical magnetic gradient (VMG), ground penetrating radar (GPR), and electromagnetic line locating (EMLL) surveys. The VMG method was used to determine the presence of buried ferrous metal. The GPR survey was used to obtain a continuous reflection profile of shallow subsurface features. The EMLL survey measured conductivity values over a specific point to a depth of approximately 18 feet below ground surface (bgs). Results of the VMG survey indicated the presence of four anomalies. One of the anomalies had closures that were consistent with USTs. The anomaly covered an area of ' approximately 45 by 100 feet in the central portion of the property. The GPR data was collected over the four anomalies identified by the VMG. The GPR data did not indicate signatures within the upper two to four feet that are large enough to represent a UST. The EMLL investigation did not indicate the presence of near surface metal that may have represented a UST. However, it did define the location of a utility line in the central portion of the site running in a northerly direction. Refer to Appendix A for the ' Geophysical Survey Report 2.3 Soil Borings Ten shallow soil borings were advanced at the site. Four of the borings were advanced inside of the anomaly detected by the VMG survey. Subsurface soil samples were collected utilizing a geoprobe. Two soil samples were collected from each borehole (unless subsurface conditions prevented borehole completion): one at 10 feet bgs and one at 15 feet bgs. URSGWC continuously logged each borehole in accordance with the Unified Soil Classification System. Refer to Appendix B for the soil boring logs. Samples were collected in acrylic sleeves. The ends of the sleeves were sealed with TeflonTM tape and polyethylene end caps, placed in a cooler, and transported under chain- of-custody protocol to Chromalab of Pleasanton, California, a State-certified laboratory. All down-hole equipment was decontaminated between sample locations. ' Each sample was analyzed for total petroleum hydrocarbons-diesel (TPH-D), TPH- gasoline (TPH-G), benzene, toluene, ethylbenzene, and xylenes (BTEX), and lead. Samples were not analyzed for methyl-tertiary-butyl-ether(MTBE), because this additive was not used in gasoline during the 1960s. The borehole locations are presented in Figure 2. R&M/Arch Rd/43-00066762.00.5000