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Additional Site Assessment Report 5 The Southland Corporation,Store#17334,4501 North Pershing Avenue,Stockton,CA January 15, 1998 The materials encountered during recent drilling at the site generally consisted of clayey silt and sandy silt to approximately 24 feet BGS,followed by Interbedded clayey silt and silty fine sand to the depths explored During drilling,groundwater was encountered at approximately 23 feet BGS 4 2 Results of Soil Sample Analyses Table 1 summarizes the laboratory analytical results for sod samples collected on September 23 and 24, and November 25 and 26, 1997 The highest benzene and TPH-G concentrations were detected in sample MWAA-25'at 0 39 mg/kg and 43 mg/kg, respectively MTBE was detected by EPA method 8020 in four of the twenty-three samples analyzed at concentrations ranging from 012 mg/kg to 81 mg/kg MTBE was confirmed In two of the same four samples and detected in two additional samples by EPA method 8260 at concentrations ranging from 0 049 mg/kg to 6 2 mg/kg TBA was detected in sample MW- 1A-21'at a concentration of 0 51 mg/kg TAME was detected in sample MWAA 21'at a concentration of 0 014 mg/kg DIPE and ETBE were not detected In any of the samples analyzed Copies of the analytical results and chain-of-custody documents are included in Appendix E 4.3 Results of Groundwater Monitonng/Analyses Groundwater monitoring and analytical data from the five wells are presented in Table 2 No measurable separate phase hydrocarbons(SP)were detected in any of the wells monitored During the monitonng and sampling on December 19, 1997,the depth to water was approximately 19 feet BGS Groundwater flow, as mapped from data collected on December 19, 1997,is to the northeast at a hydraulic gradient of 005 foot per foot(Figure 3) Figure 4 shows the lateral distribution of dissolved hydrocarbons(benzene,TPH-G and MTBE) in groundwater samples collected on December 19, 1997 Highest dissolved benzene, MTBE,and TPH-G concentrations were detected In well MW-1 at 1,200 micrograms per liter(pg/-),9,900 Vg/L,and 15,000 pg/L,respecbvely MTBE was confirmed in the same sample using EPA method 8260 at concentration of 14,000 pg/L. TBA, DIPE, ETBE, and TAME were not detected in any of tate samples collected Copies of the analytical results and chain-0f-custody are included in Appendix E 5 8 WASTE DISPOSAL A total of fourteen drums of sod and three drums of well purge water and nese water were removed from the site by Belshire Environmental Services,Inc The fourteen drums of soil were transported to TPS Technologies, Inc in Adelanto,California on December 23 and 30, 1997, pending proper treatment and disposal On December 9 and 29, 1997,water from the three drums of well purge water and rinse water were transported by Nieto&Sons to DeMenno Kerdoon in Compton,California for recycling (Appendix F) 17334iar rpt FLUOR DANIEL GTI