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Well Installation and Site Investigation Report ARCO Facility No.5469 Stockton,California Page 5 method estimates soil lithology by comparing the force (cone bearing pressure) required to advance the probe (Q) to the friction ratio (Rf) [(Rf equals sleeve friction (FS) divided by the probe tip load times the penetration pore pressure (Ud)]. A graphical diagram illustrating CPT interpretations of soil types is included in Appendix C. Computer generated CPT logs were plotted in the field, providing the field geologist a graphical log of subsurface soil lithology. The CPT test data report, which includes logs of all CPT data, graphical geologic logs, and additional information on the CPT technique, is presented in Appendix C. CPT tests were performed in accordance with American Society of Testing and Materials (ASTM) Method D3441. The location of boring CPT-1 is included on Figure 2. Soil samples were collected by driving a 1.7-inch diameter piston-type sampler, equipped with two pre-cleaned 1.25-inch diameter by 6-inch long brass sleeves, into undisturbed soil at the desired sampling interval. Additional sleeves of soil collected at each sampling interval were field screened for volatile organic compounds using a photoionization detector (PID). The soil samples were classified onsite using the Unified Soil Classification System. The lowermost intact sample tube from each interval was retained for analysis. The sample tube ends were covered with Teflon' sheets and tight fitting plastic caps. Once labeled and sealed, the samples were placed in an ice-chilled cooler. Each sample was identified on a chain-of custody form that followed the samples to the analyzing laboratory. Soil sampling intervals, soil descriptions, and PID readings are included on the borehole sampling log presented in Appendix B. Stratus and Gregg returned to the site on November 21, 2002, to collect grab groundwater samples using the Hydropunch" technique. Groundwater samples were collected by pushing the HydropunchT" sampler, with 2-inch diameter steel rods, to the desired sampling interval. The CPT operator subsequently pulled up on the steel rods, exposing a 4-foot long PVC screen. Samples were collected by lowering a metal bailer within the steel rods. Groundwater was collected in the bailer and placed in properly preserved glass sample containers provided by the laboratory. Following collection, the samples were placed in an ice-chilled cooler. Each sample was appropriately labeled and identified on a chain-of-custody form. Groundwater sampling intervals are included on the borehole sampling log presented in Appendix B. .Analytical Methods Soil and groundwater samples were forwarded to Sequoia Analytical, Inc., a California state-certified laboratory (ELAP #1210), for chemical analysis under strict chain-of-custody procedures. Soil samples were analyzed for TPHG using USEPA Method 8015B Modified, for benzene, toluene, ethylbenzene, and total xylenes (BTEX) using USEPA Method 8021B, and for MTBE, TBA, ethyl tertiary butyl ether (ETBE), di-isopropyl ether (DIPE), tertiary amyl methyl ether (TAME), and 1,2-dichloroethane (1,2-DCA) using USEPA P:1Bp-Arco for URS154691Reports\S469report2003.doc