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Phase II Environmental Site Assessment Manteca Multimodal Station Project, Southeast of Moffat Boulevard and Main Street,Manteca, California County EHD and the CVRWQCB determine screening levels on a case-by-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 Comparison to MCLS and SFBRWQCB ESLs VOCs and TPH-g were detected in two of the groundwater samples (B 1 and 133) collected from the soil borings advanced along the southern boundary of the site. The detected concentrations of VOCs in groundwater were compared to State of California Department of Public Health (DPH)maximum contaminant levels (MCLS) for contaminants in drinking water. However, because acetone does not have an established MCL, the detected concentration of acetone was compared to SFBRWQCB ESLs for contaminants in drinking water. In addition, MCLS have not been established for TPH in drinking water,therefore, the detected concentration of TPH-g in B3 was also compared to SFBRWQCB ESLs for contaminants in drinking water. As shown in Table 2,the detected concentrations of VOCs and TPH-g in the groundwater samples collected from beneath the site do not exceed the MCLs or ESLs to which they were compared. Conclusions Regarding TPH-g and VOCs in Groundwater VOCs and TPH-g were detected in two of the groundwater samples (B 1 and 133) collected from the soil borings advanced along the southern boundary of the site. VOCs and TPH were not detected in any of the five foot deep soil samples collected from B 1 through B5. 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(or south/southeast) of the subject site. Except for acetone,the VOCs detected in the groundwater are typically associated with gasoline. It appears likely that the VOCs in groundwater originated from the Standard Oil Company Supply Station site or other industrial facility to the south that currently or formerly stored tanks of gasoline, diesel or oil products. Based on the results of this assessment,there is no reason to believe that the VOCs and TPH in groundwater originated from the subject property. Furthermore, because none of the detected VOC and TPH-g concentrations exceeded the MCLs or SFBRWQCB ESLs for drinking water, it is reasonable to anticipate that further investigation or remediation of the groundwater beneath the site would not be required by a regulatory agency. CONCLUSIONS AND RECOMMENDATIONS Lead in Soil Sample RB4 (0.5 feet below rade): 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 handling. Therefore, if the area of RB4 is to be graded during redevelopment of the site,then,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. Rincon Consultants 15