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d 1 . 0 INTRODUCTION On behalf of the San Joaquin County Facilities Management Department, Ramage Environmental has prepared this Work Plan, Additional Site Investigation for submittal to San Joaquin County Environmental Health Division (EHD) and to the Central Valley Regional Water Quality Control Board (RWQCB . EHD verbally requested this work plan on February 13 , 2004 . This document also includes the groundwater monitoring results for the Fourth Quarter 2003 . 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 building (Figure 2) . 1 .2 Previous Work 1 . 2. 1 Initial Soil Borings In May 1994 , Kleinfelder drilled two soil borings (designated B- 1 and B-2) at the south ends of each UST (Figure 2) . Kleinfelder documented the results of the investigation in Environmental and Geotechnical Assessment Report and Tank Removal Plan, dated August 26 , 1994 . Both soil borings were drilled to total depths 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 soil samples from the bottom of the boreholes were not submitted for laboratory analysis . Groundwater was not encountered during the investigation . The soil sample analytical results are summarized in Table 1 . I � 4 it I