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Geological Technics lKc. *.✓ N%.01 Page 2 Golden State Smog Check SI Report Project No.: 947.2 December 7,2001 California. A review of the Haines records reveals that the Property has been in commercial use (automotive related businesses) since 1950. The Sanborn records reveal that the Property was used for residential purposes from 1917 through 1950. The assessor's records revealed that the Property was used as a gasoline/automotive service station from 1950 through 1968. The San Joaquin assessor's records indicate that one 5,000 gallon, two 2,000 gallon and one 1,000 gallon underground storage tanks were used during the 1950s and 1960s. The locations of the former tanks are not known nor do we know if any underground storage tanks still remain on the site. There is a patch of asphalt on the southern portion of the property that may be the fonner location of one or more of the USTs (Figure 2). Currently there is one building, two awnings, vent piping on the east wall and a former dispenser island. The Property, which is approximately 10,000 square ft, is covered entirely by concrete or asphalt. At the present time two businesses are in operation on the Property. There is an automotive smog inspection shop and an automotive detail shop. 2.0 SCOPE OF INVESTIGATION On November 21, 2001, Geological Technics Inc. supervised the drilling of 2 boreholes using GeoProbe direct push method to investigate the possibility of soil being impacted by petroleum hydrocarbons. 2.1 Borehole Drilling& Soil Sample Collection The Site Map in Figure 2 shows the locations that the boreholes.were drilled. The boreholes were drilled with a GeoProbe rig owned and operated by V&W Drilling of Rio Vista, CA (C57# 720904). The GeoProbe advances a continuous coring tool with a pneumatic hammer to a selected depth. The soil sample enters an acetate cylinder contained in the coring tool. Upon filling, the coring tool is pulled from the hole and the cylinder is removed. The cylinder is then cut and the selected interval is preserved for laboratory analysis. The remainder of the sample was used for geologic logging. All soil samples were capped with plastic end caps, labeled and placed in a cooler at 4° Celsius for transport to the laboratory following Chain of Custody protocol. The GeoProbe borings were advanced to a depth of 26-feet bgs. Soil samples were collected at 5-foot intervals for geologic logging. The 10-foot sample from borehole #1, the 15.5-foot sample from borehole #2 and the 25-foot soil samples from each borehole were submitted to Sherwood Labs in Hilmar, CA for analysis. Since only selected samples were to be submitted for laboratory analysis, a screening process was used to gather additional information through field observation. This information was used to detennine which samples were to be analyzed. The following characteristics were noted in the screening process: • sediment type, especially grain size and clay content • moisture content • visible evidence of contamination, i.e., color change due to reduction of iron or discoloration from hydrocarbons and other pollutants