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' DRAFT <br /> For lead, the 95 percent UCL lead concentration of 90 mg/kg in soils was well below the <br /> child receptor-based lead in soil target concentration and the industrial receptor-based <br /> lead in soil target concentration. Consequently, the soil lead concentration in Area 2B <br /> does not appear to represent a potential health hazard. <br /> 2.3 Area 3 <br /> Noncarcinogenic hazards and carcinogenic risks at Area 3 are presented in Table C-6. <br /> Noncarcinogenic HIs for the outdoor construction worker, landscape maintenance <br /> worker, and commercial worker were less thane one. HIs were greater than one for the <br /> resident, primarily due to the presence of arsenic in soil. Arsenic concentrations in Area <br /> 3 soils ranged from 3.3 mg/kg to 12 mg/kg. <br /> ' Excess cancer risks at Area 3 were 1.17E-10 for the construction worker, 5.33E-05 for the <br /> landscape maintenance worker, and 1.31E-10 for the commercial/industrial worker, and <br /> 8.81 E-05 for the resident. <br /> The elevated noncarcinogenic hazard and carcinogenic risk for the resident are primarily <br /> due to arsenic in soil through the ingestion and dermal and routes of exposure. Typical <br /> background arsenic concentrations reported by Bradford, et al (1996) ranged from 0.59 to <br /> 11 mg/kg for soils collected throughout California. The U.S. EPA Region 9 (1999) <br /> residential preliminary remediation goal (PRG) for arsenic (cancer endpoint) is 0.39 <br /> mg/kg and 22 mg/kg for the non-cancer endpoint. The industrial soil PRG is 2.7 mg/kg <br /> for the cancer endpoint and 440 mg/kg for the noncancer endpoint. The representative <br /> soil concentration used in the risk calculations for Area 3 was 7.98 mg/kg which exceeds <br /> the residential EPA Region 9 PRG but falls within the reported California soil <br /> background arsenic concentrations (Bradford et al., 1996). Available site soil data <br /> indicate that the highest arsenic concentration at Area 3 was 12 mg/kg well below the <br /> non-cancer endpoint PRG for industrial site use although greater than the cancer endpoint <br /> PRG for industrial site use. Further evaluation of natural background concentrations of <br /> ' SOMA 99-2218 17 12/10/99 <br />