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r -CLEARWATER <br /> G R O U P, I N C <br /> Environmental Services <br /> Ms Lori Duncan March 27, 2000 <br /> San Joaquin County Public Health Services / Environmental Health Division <br /> 304 East Weber Avenue <br /> Stockton, CA 95202 <br /> I <br /> ' Confirmation Soil Sampling, <br /> Groundwater Monitoring - First Quarter 2000, <br /> and Closure Request <br />' Ruiz Grocery, 4491 West Durham Ferry Road, Tracy, CA <br /> Dear Ms Duncan, <br /> tIntroduction <br />' This report, prepared by Clearwater Group (Clearwater) on behalf of Mrs Stella Ruiz, presents the <br /> results of recent confirmation soil sampling and first quarter 2000 groundwater monitoring activities at <br /> Ruiz Grocery, 4491 West Durham Ferry Road, Tracy, California (Figure 1) The work described here was <br /> originally proposed in Clearwater's Groundwater Monitoring Report - Fourth Quarter 1999 and <br /> Workplan for Confirmation Soil Borings dated November 15, 1999 The scope of work consisted of the <br /> drilling four confirmation soil borings for the purposes of evaluating the extent of post-remediation <br /> soil contamination, and to evaluate the effectiveness of the soil vapor extraction system (SVE)/ air <br /> sparge (AS) system operated from October 1998 to September 1999 In addition to the confirmation soil <br /> borings, all of the on-site monitoring wells were sampled in February 2000 The workplan was <br /> approved by the San Joaquin County Public Health Services / Environmental Health Division <br /> (SJCPHS/EHD) in correspondence dated December 31, 1999 <br /> Background <br /> Site History <br /> Two gasoline USTs and dispensers were removed from the site in 1988 Seven monitoring wells (MW- <br /> 1 through MW-7), one groundwater recovery well (RW-1), four soil vapor extraction wells (VW-1 <br /> through VW-4), and two air sparge wells (SW-1 and SW-2) have been installed at the site A domestic <br /> well (DW), screened in a deeper water bearing zone, also exists at the site (Table 1) The extent of soil <br /> and water contamination was delineated Based on historical investigation data, it was calculated that <br /> approximately 5,050 lbs (842 gals) of gasoline contaminants were present in the vadose zone prior to <br /> remediation Based on cumulative site data, Clearwater recommended construction of a remediation <br /> system consisting of combined groundwater and soil vapor extraction with air sparging The results of <br /> this work were presented in Clearwater's Problem Assessment Report, Feasibility Study, and Remedial <br /> ` Action Plan dated February 21, 1996 <br /> 520 Third Street,Suite 104 o Oakland,Cahfonua 94607 o Telephone 510-893-5160 o Fax 510-893-5947 <br />