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' Creo[og&al TeCA41CS Ar_ Page 4 Additional Site Characterization &4°i Quarter Groundwater Monitoring Project No. 1030.2 February 20,2004 See Appendix C, Boring Logs for more information. ' 2.1.2 Soil Laboratory Analyses The following summarizes the soil sample testing used for this phase of work. The soil samples collected on November 12, 2003, were delivered to Sherwood Labs (California ' ELAP No. 1400), of Hilmar, California, for the following analyses: • Benzene, toluene, ethylbenzene and xylene(BTEX) by EPA method 8020 • Gasoline range petroleum hydrocarbons (TPH-Gasoline)by EPA method 8015(m) • MTBE by EPA method 8020 (positive results confirmed by EPA method 8260) ' The detection limits for these compounds are listed in the laboratory data sheets included in Appendix B and summarized in Table 2 of Appendix A. A Chain of Custody was completed for all samples collected and tracked to ensure sample integrity. ' As required under AB2886, the depth to groundwater data was submitted electronically to GeoTracker on January 7, 2004, and the confirmation number is 6530377566. ' 2.2 GeoProbe Investigation To further investigate the lateral extent of soil impacted with petroleum hydrocarbons, GTI proposed to advance ten (10) GeoProbes boreholes at the site. On November 10 and 12, 2003, GTI and V&W Drilling mobilized to the site to install GeoProbe boreholes and collect soil samples. ' Ten GeoProbe boreholes were advanced in the locations indicated in Figure 3. The borings were logged continuously and selected soil samples were sent to the laboratory for analyses. Groundwater was encountered at approximately 12 feet bgs during the GeoProbe investigation. 2.2.1 Soil Sampling Procedure ' The boreholes were drilled with a GeoProbe rig owned and operated by V&W Drilling of Isleton, CA (C57# 720904). The GeoProbe was advanced with a pneumatic hammer and soil samples were collected continuously in four-foot sections. At four-foot intervals, the coring tool, attached to the pneumatic hammer, was opened and advanced further to fill the ' core barrel. 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 was then cut and the selected interval was capped with plastic end caps and placed on ice ' for shipment to the laboratory. The remainder was used for geologic logging. A boring log providing sediment description using the USCS and other field observations was maintained by a professional geologist working under the supervision of a registered geologist and is included in Appendix C. _ - -- Two soil samples from each borehole were submitted to the laboratory for analysis. A ' surnmary of the soil analytical data from the GeoProbe is included as Table 3 while the laboratory data is included in Appendix B.