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n Site History Canepa's Car Wash(Pacific Avenue) Page 5 of 6 much higher than previously detected The groundwater sample analytical results from well MW-12D continue to indicate a trend of lower contaminant concentrations since the initial sampling event for this well conducted on October 25, 2001 The laboratory analytical results indicate a trend of increasing MTBE concentration at MW-3 The SJCEHD has indicated that quarterly groundwater monitoring continue at the site In a letter dated July 30, 2002, Condor requested temporary shutdown of the SVE unit based on data that indicates dwindling influent concentrations and to allow its relocation as part of the additional development of the site planned by the property owner The SJCEHD and Condor have agreed, however, that the SVE unit will be operated until development is imminent Regular maintenance of the SVE system, which included belt replacement, was conducted on September 4, 2002 In order to maximize the carbon use, change-out occurs in the first carbon unit when breakthrough is detected in the second carbon unit The procedure for carbon system change-out is as follows upon measurable breakthrough from the second carbon unit, the carbon in the first unit will be replaced with virgin coconut shell vapor phase carbon The units will be reversed in flow direction with the partially used unit as the first unit and new carbon in the second unit The weekly PID reading of the SVE system effluent indicated breakthrough on September 20, 2002, at 2 parts per million by volume The system was shut down on September 23, 2002, and change-out of the carbon system was conducted on September 30, 2002 In addition, after the change-out, quarterly soil vapor samples from the influent, • mid tank and effluent sample ports were colleted for laboratory analysis Laboratory analytical results from the mid tank soil vapor sample indicated concentrations of BTEX constituents and MTBE below the laboratory reporting limit, and, therefore, the destruction efficiency of the SVE system was estimated at 100% Condor performed quarterly monitoring activities at the site on October 14 and 15, 2002 Laboratory analytical results of the groundwater samples indicated concentrations of petroleum hydrocarbon constituents consistent with historical data The groundwater analytical results for SVE-4 were generally consistent with the previous groundwater analytical results reported for SVE-4 during the July 2002 monitoring event The groundwater sample analytical results from well MW-12D continue to indicate a trend of lower contaminant concentrations since the initial sampling event for this well conducted on October 25, 2001 The MTBE concentration detected in groundwater samples collected from MW-3 was lower than previously detected Condor prepared a Problem Assessment Report (PAR) and a Corrective Action Plan (CAP) for the site, dated October 18, 2002 Condor reported in the Third Quarter Groundwater Monitoring Report, dated August 19, 2002, that the laboratory analytical result for MTBE in the sample collected from SV-8 on July 2, 2002 was 5,500 [tg/L Upon review of the July 2, 2002 data submitted in Electronic Deliverable Format (EDF) to Condor by Excelchem, a discrepancy was noted in the original laboratory report for MTBE in the sample collected from SV-8 The EDF data indicated an MTBE concentration of 3,600 µg/L for the groundwater sample collected from SV-8 The EDF data for SV-8 was determined to be correct by Excelchem and a revised laboratory report was issued A copy of the corrected laboratory certificate of analyses and sham-of- _ custody record for the July 1-3, 2002 monitoring event and a revised summary of Historical Groundwater Monitoring Data were included in the Fourth Quarter Groundwater Monitoring Report, dated November 20, 2002