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Phase II Environmental Site Assessment Manteca Multimodal Station Project Southeast of Moffat Boulevard and Main Street Manteca, California RB 14 does not exceed the screening levels to which it was compared, it does not warrant further assessment or remediation of zinc at the site. Lead. The results of the STLC analyses for R134 at 0.5 feet had 11.5 mg/L soluble lead in the soil sample. Because this result exceeds the STLC threshold of 5 mg/L, if soil is excavated from this area, it would be classified as a California Hazardous Waste and would require special handling during excavation. Note that the sample collected from 2 feet below grade from RB4 had a total lead concentration of 2.38. This concentration is low and would not require special J 1:.. . T!. !`. •!`i t e'-£!A 2 : T ! P.1 ,t 11QL1LL1111g'. 111CICIUM, 11 LIM dIr-d Ul DtD'+ 1J LU UG 91ULICU UL11111g IGurvulupIIIGIIL UL LIIU JILL, LLICI1, prior to grading,the soil in the vicinity of RB4 (up to 2 feet below grade) should be excavated and disposed offsite at an accepting facility. TPH IN SOIL Comparison to SFBRWQCB ESLs SLs and CHHSLs have not been established for TPH in soil. In addition,the San Joaquin County Environmental Health Department(EHD)and the Central Valley RWQCB (CVRWQCB) indicate that screening levels for TPH in soil are determined on a case-by-case basis. Because the EHD and the CVRWQCB have not established screening levels for TPH in soil,the detected concentration of TPH have been compared to environmental screening levels (ESLs) established by the San Francisco Bay RWQCB (SFBRWQCB)to provide an idea of how other regulatory agencies approach TPH. The ESLs are described as follows: SFBRWQCB Environmental Screening Levels (ESLs,: The San Francisco Bay RWQCB has established ESLs for chemicals commonly found in soil and groundwater at sites where releases of hazardous chemicals have occurred. The ESLs are considered to be conservative. Under most circumstances,the presence of a chemical in soil, soil gas or groundwater at concentrations below the corresponding ESL can be assumed to not pose a significant, long term(chronic)threat to human health and the environment. Additional evaluation will generally be necessary at sites where a chemical is present at concentrations above the corresponding ESL. Active remediation may or may not be required depending on site specific conditions and considerations. TPH-Q: TPH-g was not detected in any of the soil samples collected from the site. TPH-d.• As shown in Table 1, low concentrations of TPH-d ranging from 3.2 to 35 mg/kg were detected in five soil samples collected from beneath the site at depths of 0.5 feet below grade. The SFBRWQCB soil screening level for TPH-d in shallow soil (less than 3 meters [9.8 feet] below grade) is 83 mg/kg. The detected concentrations of TPH-d(3.2 to 35 mg/kg)are below the SFBRWQCB screening level of 83 mg/kg. TPH-o: As shown in Table 1, low concentrations of TPH-o ranging from 6 to 82 mg/kg were detected in 14 soil samples collected from beneath the site at depths of 0.5 feet below grade. The SFBRWQCB soil screening level for TPH-o in shallow soil(less than 3 meters [9.8 feet] below grade) is 370 mg/kg. The detected concentrations of TPH-0 (6 to 82 mg/kg) are below the SFBRWQCB screening level of 370 mg/kg. Conclusions Regarding TPH in Soil Because none of the detected TPH concentrations exceed the SFBRWQCB screening levels, it is reasonable to expect that further investigation or remediation of the TPH detected in soil beneath the site would not be required by a regulatory agency. However, because the San Joaquin r14 Rincon Consultants