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QUARTERLY SUMMARY REPORT <br /> FIRST QUARTER- 2003 <br /> (January–March) <br /> Tosco (76) Service Station No 6981 <br /> 4707 Pacific Ave <br /> Stockton,CA <br /> COUNTY, San Joaquin RWQCB Office. Central Valley Region,Sacramento Branch <br /> BACKGROUND The USTs were replaced in 1988 To date 16 onsite and 5 offsite borings have been drilled and 13 <br /> groundwater monitoring wells, one pumping test well,and six vapor extraction wells installed 1,600 cubic yards(cy')of soil <br /> were excavated and aerated Groundwater monitoring began in February 1990 Vapor Extraction Test was performed in March <br /> 1992 A pump was test was performed in August 1992 A Vapor Extraction System(VES)was installed and operation initiated <br /> in September 1994 Wells MW-3, MW-10, MW-12, and MW-13 were abandoned to facilitate re-construction of street <br /> intersection Submitted work plan to install one offsite groundwater monitoring well and drill one soil boring in September <br /> 1997 Submitted Work Plan Addendum (dated 2117199) for additional borings/wells Submitted additional subsurface <br /> investigation (borings/wells) report date 11/15/99 USTs and product piping removed and samples collected in April 2000 <br /> Approximately 100 cy;of sot were over-excavated from the product piping/dispenser areas Submitted UST/line removal and <br /> sampling report(dated 8129100) Pulsing of the VES was initiated in November 1998 VES has not operated since April 2000 <br /> (UST removal and electrical service rerouted, blower failure) An ozone microsparge system was installed in 2001 and <br /> commenced operation in December of 2001 <br /> RECENT QUARTER ACTIVITIES Monitored and sampled groundwater monitoring wells Prepared and submitted the <br /> quarterly summary report Collected operational progress samples from the ozone sparge system Submitted Ozone <br /> eMicrospatge System First Semi-Annual Status Report, dated March 3, 2003 <br /> NEXT QUARTER ACTIVITIES Monitor and sample groundwater monitoring wells Prepare and submit a quarterly <br /> summary report Collect operational progress samples from the ozone sparge system <br /> CHARACTERIZATION/REMEDIAL STATUS <br /> Soil contamination delineated? -es <br /> Dissolved groundwater delineated des <br /> Free product delineated? n/a <br /> Amount of hydrocarbon contaminant recovered <br /> this quarter/tota19 0114,977' (lbs ) <br /> Soil remediation in progress? <br /> - anticipated start? 9/94 <br /> anticipated completion9 unknowns <br /> Dissolved/free product remediation <br /> in progress9 Yes, ozone microsparge for dissolved <br /> hydrocarbons <br /> anticipated start? 12/19/02 <br /> anticipated completion? unknown <br /> 1 Approximately 14,794 pounds of TPHg and 183 pounds of benzene have been extracted through 3Q02 <br /> 0 <br /> 140124 qsr 1 <br />