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Additional Site Assessment Report and Work Plan for Additional Subsurface Investigation 1 The Southland 22MRration,Store#1997611399 N Main St Manteca California June S.1938 1 1.0 INTRODUCTION This report is submitted by Fluor Daniel GTI, Inc to summarize the results of the soil and groundwater ' assessment conducted at Southland Store No 19976 located at 1399 North Main Street in Manteca, California (Figure 1) The scope of work included sampling soil from three geoprobe borings near the underground storage tank(UST) pad and pump island In addition,groundwater samples were collected 1 from the three bonngs(Figure 2) The worts scope was designed to fulfill the requirements of the San Joaquin County Public Health Services(SJCPHS) 1 The work described in this report was completed at the site on April 29, 1998, in accordance with the scope of work outlined in Fluor Daniel GTI's Wait Plan for Subsurface Inveshgadon,dated March 31, 1998 and 1 the Addendum to Work Plan for Subsurface Inveshgafron,dated April 20, 1998, which was accepted by the SJCDEH In addition,this report presents a work plan for additional site invesbgabon at the subject site The scope of work includes collection of background information,drilling and sampling of three soil bonngs, installation of monitoring wells in the bonngs,collection of groundwater samples from the monitoring wells, liquid level 1 gauging of the monrtonng wells, and preparation of an assessment report summarizing the methods and results of the work preformed 2.0 BACKGROUND On September 19, 1996, Maness Environmental Services removed three USTs from site, Fluor Daniel GTI 1 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 1 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 1 method 8260 was used to confirm Its presence 1 Table 1 summarizes the sod analytical results of the sod 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 1 10,000-gallon USTs(Figure 2) Sods 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 On September 20, 1996, a total of seven soil samples were collected from the floor of the additional tank ' pit excavation six samples at 13 feet BGS and one sample at 15 feet BGS Soil samples were collected 19976=r rpt1 FLUOR DANIEL GTI