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t 1.0 INTRODUCTION On behalf of the San Joaquin County Facilities Management Department, Ramage Environmental has prepared this Preliminary Investigation and Evaluation Report for submittal to San Joaquin County Public Health Services Environmental Health Division (PHS/EHD) and to the Central ' Valley Regional Water Quality Control Board (RWQCB) The project scope of work was completed according to Ramage Environmental's Work Plan, ' Preliminary Investigation and Evaluation, dated .July 14, 2000 On July 25, 2000, PHSIEHD approved the work plan A copy of the work plan approval letter is included in Appendix A 1 1 1 Site Location and Description ' The subject site is an active single-level parking garage located at 130 N Hunter Street in Stockton, California (Figure 1) Two former gasoline underground storage tanks (UST) existed ' under the sidewalk, adjacent to the west side of the garage building, and two former gasoline dispensers on a single island existed approximately 20 feet inside the west wall of the budding (Figure 2) 12 Previous Work ' In May 1994, Kleinfelder drilled two sod borings (designated B-1 and B-2) at the south end of each UST (Figure 2) The results of the investigation were documented in Kleinfelder's Environmental ' and Geotechnical Assessment Report and Tank Removal Plan, dated August 26, 1994 ' Both soil borings were drilled to a total depth of approximately 25 feet below ground surface (bgs) Based on field screening with a photoionization detector (PID), only the soil sample with the highest organic vapor concentration from each boring was submitted for laboratory analysis The ' soil sample collected at 20 feet from B-1 contained 290 milligrams per kilogram (mg/kg) of Total Petroleum Hydrocarbons (TPH)-as-gasoline, 4 7 mg/kg of ethylbenzene, and 8 0 mg/kg of xylenes The soil sample collected at 18 feet from B-2 contained 250 mg/kg of TPH-as-gasoline, 1 7 mg/kg of ethylbenzene, and 7 0 mg/kg of xylenes The sod samples from the bottom of the boreholes were not submitted for laboratory analysis Groundwater was not encountered during ' the investigation These sod sample analytical results are summarized in Table 1 1 4