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Response A total of 15 soil samples were collected from the excavation. All samples with the exception of three underwent laboratory analysis. These samples include EW1-11.0', SW2-10.0', and SW3- 10.01 . Initially during excavation confirmation sampling activities, soil samples were being collected at a depth of 12 feet below ground surface at the direction of PHS/EHD personnel. At the suggestion of Smith Environmental's geologist, soil samples were also collected at a depth of 10 feet blow ground surface where field conditions permitted. Water in the excavation pit appeared to stabilize at approximately 10 feet below ground surface. Field observations during the excavation indicated soil hydrocarbon contamination was limited to below 10 feet below grade near the eastern and southern boundaries of the excavation. Therefore when laboratory analysis of samples SW2-12.0' and SW3-12.0' indicated nondetectable results, the corresponding 10.0' soil samples were not analyzed. Soil sample EW1-11.0' was collected from a portion of the eastern sidewall which was excavated. Due to obvious soil contamination observed during the collection of this sample the excavation was continued an additional 10 feet eastward and consequently the sample point was removed from the subsurface. All soil sample locations are shown on Figure 3. A description of all excavation soil samples collected is included as Attachment 1. Comment Conclusions regarding the distribution of lead. Response Agreement was made that those soil samples with soil contamination and one without contamination would undergo lead analysis to determine background levels. Soil samples analyzed with soil contamination included NW I, B1, B2, EW2 at 12', and WW at 8 and 10'. One soil sample without soil contamination, sample EWlb at 12.5', also was analyzed for lead. Lead analytical results of soil samples containing detectable concentrations of petroleum hydrocarbons ranged from 0.95 to 7.5 ppm. Soil samples B2 at 15.0', collected beneath the former underground storage tanks, and WW at 8', collected beneath the former fuel dispensers, contained the highest lead concentrations at 7.5 and 6.10 ppm, respectively. Laboratory analysis of the soil sample without detectable concentrations of petroleum hydrocarbons (sample EWlb- 12.5') contained 1.0 ppm of lead. Although several of the analyzed soil samples have lead concentrations above 1.0 ppm all the samples are believed to be within regional background levels for total lead. Typical lead concentrations in the San Francisco Bay Region for example range between 30 to 300 ppm. The U. S. mean lead concentration in soils and surficial materials is 16 ppm (USGS Professional Paper 1270, April 28, 1992). 15008 i\sxR-o99s.noc 3 • SNftN