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ADDITIONAL ASSESSMENT REPORT <br /> .TAY'S MINI MART <br /> STOCKTON, CALIFORNIA <br /> JUNE 2003 <br /> Soil analytical results from the geoprobe investigation are summarized in Table 1 and shown on <br /> Figure 3 The laboratory reports with COC documentation are included in Appendix B <br /> GROUNDWATER ANALYTICAL RESULTS <br /> TPH G was reported in the groundwater samples from SB-3 and SB-4 at 390 micrograms per liter <br /> (µg11) and 81 µg/1, respectively TPH D was reported in the groundwater samples from SB-3 and <br /> SB-4 at 180 micrograms per liter (µg11) and 72 µg11,respectively The laboratory noted that the <br /> TPH D results were primarily due to overlap from a gasoline range product and most likely <br /> indicate a weathered gasoline rather than diesel <br /> Benzene was reported in the groundwater sample from SB-3 at a concentration of 7 4 µg/l <br /> Toluene was ND in all three groundwater samples Ethylbenzene was reported in the groundwater <br /> sample from SB-3 at a concentration of 2 1 µg/1 Total xylenes were reported in the groundwater <br /> sample from SB-3 at a concentration of 3 5 µg/1 <br /> MTBE was reported in the groundwater samples from SB-3 and SB-4 at 6 8 ug/l and 7 2 ug/l, <br /> respectively All of the other oxygenates were ND in all groundwater samples taken EDB was <br /> . ND in all groundwater samples taken 1,2-DCA was reported in the sample from SB-3 at 31 µgll <br /> Groundwater analytical results are summarized in Table 2, and shown on Figure 4 The laboratory <br /> reports with COC documentation are included in Appendix B <br /> CONCLUSIONS AND RECOMMENDATIONS <br /> Soil and groundwater samples from the vicinity of the UST pit were non-detect for all constituents <br /> tested Soil and groundwater samples from the former piping and dispenser locations are impacted <br /> with petroleum hydrocarbons and MTBE at levels low enough to justify a nsk-based closure <br /> analysis <br /> Levels of BTEX constituents and MTBE in soils do not indicate a source significant enough to <br /> degrade groundwater to any substantive degree <br /> GHH makes the following recommendations <br /> • Perform a sensitive receptor survey for this site <br /> • Using the results of the sensitive receptor survey and previous subsurface investigation <br /> results, prepare a Risk-Based Corrective Action (RBCA) assessment to determine <br /> whether site closure is warranted <br /> 5 <br />