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Phase II Environmental Site Assessment Manteca Multimodal Station Project Southeast of Moffat Boulevard and Main Street Manteca,California TPH in Soil(0.5 feet below grade): 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. 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. Because none of the detected TPH concentrations exceeded the SFBRWQCB ESLs to which they were compared, it is reasonable to anticipate 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 County EHD and the CVRWOCB determine screening levels on a case-bv-case basis.. we recommend that the City of Manteca discuss the results with the San Joaquin County EHD,to confirm that the use of the SFBRWQCB ESLs is acceptable for this site,or to determine a site specific screening level for the TPH in soil beneath the site. TPH-g and VOCs in Groundwater: VOCs and TPH-g were detected in two of the groundwater samples (B1 and B3)collected from the soil borings advanced along the southern boundary of the site. Because VOCs and TPH were not detected in any of the five foot deep soil samples collected from B 1 through B5, and because groundwater in the vicinity of the site is expected to flow in a northwesterly/northerly direction, it is reasonable to conclude that the TPH and VOC concentrations in groundwater located in the vicinity of B3 and B 1 are originating from an offsite source located hydraulically upgradient(south/southeast)of the subject site. Furthermore, because none of the detected VOC and TPH-g concentrations exceeded the MCLS or SFBRWQCB ESLs for drinking water, it is reasonable to expect that further investigation or remediation of the groundwater beneath the site would not be required by a regulatory agency. During the redevelopment of the site, the City of Manteca should notify the contractor of the possibility of encountering contaminated soil beneath the site(in the vicinity of RB4 and possibly other areas not identified during this Phase I1 ESA). Prior to redevelopment of the site, a Soil Management Plan should be prepared to provide guidance for the proper handling, onsite management and disposal of contaminated soil in the vicinity of RB4, and other areas, if encountered, during excavation and grading activities. REFERENCES The following published reference materials were used in preparation of this Phase II ESA: Bradford, G.R., Chang,A.C., Page, A.L.,Bakhtar,D.,Frampton,J.A., and Wright, H., Background Concentrations of Trace and Major Elements in California Soils, March 1996. California Department of Water Resources, California's Groundwater Bulletin 118,2003. California Department of Conservation, Geologic Map of the San Francisco-San Jose Quadrangle, 1990. California Environmental Protection Agency(CaUEPA), Use of California Human Health Screening Levels (CHHSLs) in Evaluation of Contaminated Properties, January 2005. California Geological Survey, California Geomorphic Provinces Note 36, December 2002. California Regional Water Quality Control Board, Water Quality Control Plan (Basin Plan)for the California Regional Water Quality Control Board, Central Valley Region, 1991; 16 Rincon Consultants