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ft) rk Environmental Assessment Report 2 Chevron U S A Products Company, 508 Charter Way,Stockton CA May 11, IM 23 Soil Sampling Soil samples were collected from boreholes MWA, MW -2, MW -3 and SBA at 5 -foot Intervals during drilling, beginning at approximately 5 feet BGS Samples were collected using a 2 5 -inch O D split -spoon sampler, lined with three 2 -Inch -diameter by 6 -Inch -long brass sample tubes The sampler was driven 18 Inches ahead of the augers at each sample point Soil samples were field screened for hydrocarbon vapors using a photo -ionization detector (PID) Soil was logged using the Unified Sod Classification System by a Groundwater Technology field geologist working under the supervision of a California registered geologist (Appendix B) One sample tube from each 5 -foot Interval was sealed, labeled and placed on Ice in an Insulated container for transport under chain -of -custody manifest to Sequoia Analytical (Sequoia), a California state -certified analytical lab In Sacramento Based on PID readings and the depth to first groundwater observed in each boring, 16 soil samples were selected for laboratory analysis (Tables 1 and 2) Samples were analyzed for benzene, toluene, ethylbenzene and total xylenes (BTEX), and total petroleum hydrocarbons -as -gasoline (TPH-G), using U S Environmental Protection Agency (EPA) methods 5030/8020/modified 8015 Six samples collected from boring MW -1 were also analyzed for total petroleum hydrocarbons -as -diesel (TPH-D) using EPA method 355018015, and total oil and grease via Standard Method (SM) 5520 EBF In addition to the above analyses, samples collected from the 10- and 35 -foot depths from boring MW -1 were analyzed for purgeable halocarbons via EPA method 8010, extractable organics using EPA method 8270, and the metals cadmium (Cd), chromium (Cr), lead (Pb), nickel (Ni) and zinc (Zn) Upon completion of drilling and sampling, boring SBA was backfilled with grout to surface on March 16, 1995 2.4 Groundwater Monitoring Well Installation and Development A groundwater monitoring well was installed in each of bonngs MW -1, MW -2 and MW -3 on March 15 and 16, 1995 Each monitoring well was constructed of 2 -inch -diameter schedule 40 PVC blank casing and 0 020 -inch slot well screen with flush threads Well screen was installed at a depth of 30 to 50 feet BGS in each well A #3 -sand filter pack was installed in the annulus from the bottom of each borehole to 2 feet above the top of the well screen, followed by a well seal consisting of a 2 -feet thick bentonite layer overlain by neat cement (grout) to ground surface Each well was secured by a locking expandable well cap and fitted with a traffic -rated well box set in concrete Details of well construction are presented in the drilling logs (Appendix B) Figure 2 shows the location of the monitoring wells on site • 0071EAp,ptfChv Joey ❑❑❑ TTECCHJNW)GY-,