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' eola kat rechAks Inc. Page 5 Additional Site Characterization &4`h Quarter Groundwater Monitoring Project No. 1030.2 February 20,2004 2.2.2 Soil Laboratory Analyses The following summarizes the soil sample testing used for this phase of work. The soil samples collected on November 10 and 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 3 of Appendix A. A Chain of Custody was completed for all samples collected and tracked to ensure sample integrity. rAs required under AB2886, the depth to groundwater data was submitted electronically to GeoTracker on January 7, 2004, and the confirmation number is 6530377566. ' 2.3 Soil Boring Investigation In accordance with the directive in the July 18, 2003, letter from SJCEHD, GTI advanced two soil borings at the site. The work was done to investigate the possible NNW/SSE ' trending sand channel. Grab groundwater samples were to be collected at 10 and 15 feet bgs. However, groundwater was encountered at 12 feet bgs and the sample depths were changed to 12 and 16 feet bgs. 2.3.1 Soil And Groundwater Sampling Procedure The two soil 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. Upon reaching groundwater at approximately 12 feet bgs, the core barrel was removed and a 3/" PVC casing with a one foot screen interval was placed in the borehole. Water samples were collected using a Waterra check valve and dedicated tubing. After the water samples were collected, the PVC casing was removed and the core barrel was advanced to 16 feet bgs and another water sample was collected in the same manner. ' 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 soil boring were submitted to the laboratory for analysis. A summary of the soil analytical data from the soil boring investigation is included as Table 3 ' while the laboratory data is included in Appendix B.