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Site Background Canepa's Car Wash,Park Street Page 3 of 7 • The groundwater table has been above the top of all well screens since the August 1996 monitoring event The average depth to groundwater in the monitor wells was approximately 26 86 feet below the surveyed well collar measuring points on October 17, 2002 The groundwater elevation contours indicated that the groundwater gradient was generally toward the northeast, consistent with previously reported groundwater gradients The average groundwater elevation decreased by approximately 1 60 feet since July 5, 2002 Quarterly groundwater monitoring activities were conducted on January 13, 2003 The laboratory analytical results for the groundwater samples collected from MW-1, MW-4, MW-6, and MW-7 indicated that BTEX constituents were not detected at or above laboratory reported detection limits, but were detected in MW-2 and MW-5 Benzene was detected in the groundwater samples collected from MW-3 TPH-G was detected in the groundwater samples collected from MW-2, MW-3, MW-5, and MW-7 MTBE was detected in the groundwater samples collected from MW-3 and MW-6 When retested using EPA Method 8260B, MTBE was not detected in MW-2 The concentration of benzene in MW-2 generally has an inverse relationship with groundwater elevation In contrast, benzene concentrations in MW-5 have generally increased as the groundwater elevation has increased The concentration of MTBE in MW-6 has ranged from < 0 5 to 23 µg/L over time and was below California EPA's maximum contamination level (MCL) of 13 micrograms per liter (pg/L) for January 2003 Low concentrations of MTBE have continued to be present in groundwater samples collected from MW-3 (7 2 pg/L for January 2003) It is possible that the low concentrations of MTBE represent background concentrations since they are at the up-gradient extent of the Site The groundwater table has been above the top of all well screens since the August 1996 monitoring event . The average depth to groundwater in the monitor wells was approximately 26 86 feet below the surveyed well collar measuring points on January 13, 2003, the same as the previous quarter The groundwater elevation contours indicated that the groundwater gradient was generally toward the northeast, consistent with previously reported groundwater gradients In a letter dated March 18, 2003, Mr Wong of the SJCEHD approved the work plan dated November 1, 2002 that described additional soil and groundwater investigation with CPT Upon receipt of the approval to conduct the described work, Condor initiated Site planning and preparation activities, including the procurement of off-Site access agreements and permitting with adjacent property owners Quarterly groundwater monitoring activities were conducted on April 4, 2003 The laboratory analytical results for the groundwater samples collected from MW-4, MW-6, and MW-7 indicated that BTEX constituents were not detected at or above laboratory reported detection limits in those samples BTEX constituents were detected at low concentrations in the groundwater samples collected from MW-1 and MW-3, at moderate concentrations in the sample collected from MW-2, and at relatively elevated concentrations in the sample from MW-5 MTBE was detected at concentrations of 8 2 and 13 gg/L, respectively, in the groundwater samples collected from MW-3 and MW-6 MTBE was also detected at concentrations of 600 and 350 pg/L, respectively, in the samples collected from MW-2 and MW-5 with EPA Method 8020 Reanalysis of those samples using EPA Method 8260B, however, indicated that MTBE was not present at or above the laboratory reporting limit of 5 0 µg/]L The laboratory analytical results of the groundwater samples collected on April 4, 2003 were generally consistent with historical monitoring results The groundwater table has been above the top of all well screens since the August 1996 monitoring event The average depth to groundwater in the monitor wells was approximately 26 61 feet below the surveyed