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Additional Subsurface investigation And Well Installation Report 1 The Southland Corporation,Store#19976 1399 N Main St Manteca California November 15 19W ' 1.0 INTRODUCTION ' This report is submitted by Fluor Daniel GTI, Inc (Fluor Daniel GTI)to summarize the results of site assessment conducted at Southland Store No 19976, located at 1399 N Main Street, in Manteca, California (Figures 1 through 3) The scope of work for the site assessment included the collection of background Information,the drilling of three groundwater monitonng wells (two single and one double- nested),collection of soil and groundwater samples, and preparation of this report summarizing the methods and results of the work performed The work was designed to fulfill the requirements of the San Joaquin County Public Health Services(SJCPHS) in their letter dated June 29, 1998 The work scope described in this report was completed at the site between September 2 and September 16, 1998 All work was performed In accordance with Fluor Daniel GTI's Work Plan for Additional ' Subsurface Investigation,dated June 5, 1998, and the Addendum to the Work Plan for Additional Subsurface Investigation,dated August 4, 1998,which was approved by the SJCPHS 20 BACKGROUND Underground storage tank replacement and associated soil sampling activities were conducted in 1996 On September 19, 1996, Fluor Daniel GTI collected a total of five soil samples from the tank pit area (Figure 2) One sample was collected from each end of the three USTs at a depth of 15 feet below ground surface (BGS),with the exception of the north end of the central tank that was inaccessible due to the location of the soil stockpile The samples were analyzed for benzene,toluene, ethylbenzene, and total xylenes (BTEX), methyl-tert-butyl-ether(MTBE),total petroleum hydrocarbons as gasoline(TPH-G), following EPA method 8020/modified 8015, and total lead by EPA method 6010 If MTBE was detected ' by EPA method 8020,an additional analysis by EPA method 8260 was used to confirm its presence Table 1 summarizes the soil analytical results of the soil samples collected beneath the tanks on September 19, 1996 On September 19 through 24, 1996,the tank pit was extended approximately 20 feet to the south and excavated to a depth of 13 feet BGS to accommodate the Installation of three new ' 10,000-gallon LISTS.(Figure 2) Soils encountered during the tank removal included fine sand to silty sand to a depth of approximately 10 feet BGS followed by silt,silty clay, and clayey silt with some ' interbedded fine sand to a depth of 15 feet BGS Soil encountered at 15 feet BGS appeared very moist to wet but no visual accumulation of groundwater was observed in the tank pit excavation or at the sample locations i 18978asr rpt FLUOR DANIEL GTI G�