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Subsurface Investigation Report 216 N.California St. March 24,2008 Page 3 FIELD OBSERVATIONS Soil exhibiting excavation backfill characteristics (medium brown silty sand and clayey sand) was encountered from surface to approximately 18 feet bgs. Soil staining was visible as greenish-grey discoloration from 11.5 feet bgs to the total drilling depth of 50 feet bgs. Noticeable petroleum hydrocarbon odors were coincident with stained soil. Silty clay was encountered from approximately 16 feet bgs to 26 feet bgs. From 26 feet bgs to 36 feet bgs, a downward-coarsening lithology was encountered (sandy silt to silty sand). Groundwater was encountered at approximately 30 feet bgs and sampled at 34 feet bgs, although groundwater depths in nearby monitoring wells have recently been reported at approximately 24 feet bgs. A noticeable sheen was present in the groundwater sample. Silty sand was encountered from 36 feet bgs to 42 feet bgs, followed by coarse sand with gravel from 42 feet bgs to 44 feet bgs. Sand with silt was encountered from 44 feet bgs to 48 feet bgs, followed by finer- grained silty sand with clay to 50 feet bgs. LABORATORY ANALYTICAL RESULTS Soil samples were collected from the following depths: 19.5-20 feet bgs; 29-29.5 feet bgs; 35.5-36 feet bgs; and 47.5-48 feet bgs. The four soil samples and one groundwater sample were analyzed for benzene, toluene, ethyl benzene, and total xylenes (BTEX) by EPA Method 8021B; total petroleum hydrocarbons quantified as diesel (TPH-D) by EPA Method 8015M; lead in soil by EPA Method 7420; and dissolved lead in groundwater by EPA Method 200.8. Benzene was not detected at or above the laboratory reporting limits in any of the samples. Toluene, ethyl benzene, and total xylenes were detected in all of the samples at relatively low concentrations. Lead was not detected at or above the laboratory reporting limit in the groundwater sample, and was detected at low concentrations in soil samples. Diesel-range petroleum hydrocarbons (TPH-D) were detected in all of the samples at moderate to elevated concentrations. Laboratory analytical results are summarized in Table 1,below, and included in the laboratory report with certificates of analysis and the chain of custody record(Attachment B). Table 1 Laboratory Analytical Results Constituent Sample ID Date Sampled Units: mg/kg TPH-D B T E X Lead Detection Limit 5.0 0.005 0.005 0.005 0.010 1.0 5401-SBI-20 02/19/2008 2,400 <0.005 0.31 0.74 4.5 4.2 5401-SBI-29.5 02/19/2008 4,500 <0.005 0.30 1.3 6.2 3.1 5401-SBI-36 02/19/2008 850 <0.005 0.32 0.66 4.5 2.5 5401-SBI-48 02/19/2008 1 40 1 <0.005 1 0.070 0.040 0.090 1 1.9 Groundwater: Units= /L 5401-SBI-GW-34 1 02/19/2008 1 590,000 F__<_0_.5_T 4.2 13 1 79 1 <1.0 Units: mg/kg:milligrams per kilogram,parts per million(ppm).µg/L:micrograms per liter,parts per billion(ppb) B,T,E,X=benzene,toluene,ethyl benzene,total xylenes.TPH-D=total petroleum hydrocarbons quantified as diesel. Analytical methods used:EPA Methods 8015M(TPH-D);8021B(BTEX),7420(lead in soil);and 200.8(dissolved lead in groundwater). DISCUSSION AND CONCLUSIONS Due to subsurface conditions, the drilling method used was not practical to continue with the investigation as planned. Due to increasing hydrostatic pressure with depth, soil recovery within the sampling tube decreased, while groundwater volume increased within the sampling tube. The practical limit of direct-push drilling methods at the Site appears to be approximately 25 feet below groundwater elevation. One boring was completed in the center of the former tank pit where the former over co�rnoa