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BACKGROUND The Transmission Shop (the "site") is located at the northwest corner of the intersection of Charter Way and Lincoln Street in Stockton, San Joaquin County, California(Figure 1) The site is a multi-business property located in a commercial and residential neighborhood The site contains The Transmission Shop, a transmission repair shop, and the former Rodger's Harbor Sea Food Market According to the San Joaquin County Public Health Services (SJCPHS), two underground storage tanks (USTs) were previously at the site, which was a retail service station that dispensed gasoline until sometime in the 1950s It is unknown when the first UST and dispenser island were removed Thorpe Oil of Lodi, California, removed the second UST in February 1996 Residual hydrocarbons were reported in soil samples collected from beneath the UST, however, Total Petroleum Hydrocarbons as gasoline (TPHg), Total Petroleum Hydrocarbons as diesel (TPHd), and benzene concentrations were below laboratory detection limits There are three other known former or current automobile service stations with UST facilities near the site, on the other three corners of the intersection of Lincoln Street and Charter Way (see inset, Figure 2) UST-related petroleum hydrocarbons have been detected in groundwater ' beneath each of those facilities, according to reports held by the SJCPHS The general direction of groundwater in the site vicinity is eastward (away from the Port of Stockton), according to SJCPHS IP GROUNDWATER MONITORING On May 9, 2005, a Shaw technician measured depth to groundwater and collected samples from the nine site wells, MW-1R through MW-3-R, MW-4-R-S, and MW-4R-D, and VW-1D through VW-4 Free product was not observed in the groundwater monitoring wells (see Table 1 and ' Appendix A) Sampling and analysis procedures are presented in Appendix B I The groundwater samples were analyzed by Severn Trent Laboratory (NELAP #01119CA) in West Sacramento, California, for TPHg using U S Environmental Protection Agency (EPA) Method 8015M, and for benzene, toluene, ethylbenzene, and xylenes (BTEX) and methyl tert- butyl ether (MTBE) using EPA Method 8021 B The laboratory analyses indicate that TPHg were present in the groundwater samples from wells IMW-1R, MW-4R-S, MW-4R-D, and VW-1D through VW-4, at concentrations ranging from 130 to 68,000 micrograms per liter (µg/L) BTEX were reported in samples from wells MW-1R, 1 MW-4R-S, MW-4R-D, and VW-1D through VW-4, benzene ranged from 12 to 9,100 µg/L MTBE was not detected in any sample during this event Copies of the chain-of-custody records and laboratory analytical report are included in Appendix C The groundwater elevations measured on May 9, 2005 varied from about -105 to -115 feet mean sea level and indicated a generally eastward flow Groundwater analytical data are summarized on Table 1 TPHg and benzene concentrations are shown on Figure 3 ' N VQcDP�2005\Pr118NW800341A 5ag dcx 2 SHAW ENVIRONMENTAL,INC