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I November 2005 AG -NC Project No. 97-0327 Page 4 of 8 Since initiation of ground water monitoring, ground water elevations have ranged from approximately 19.31 to 34.74 feet below mean sea level, and the dominant ground water flow direction has been between south-southwest and south-southeast with low hydraulic gradients. TPH-g has only been detected in ground water samples collected from wells MW-1 and MW-2 at concentrations as high as 770 pg/l (July 2005; MW-1). TPH-d has been detected in wells MW-1 through MW-4 at concentrations as high as 430(pg/1);however,the highest concentration ofTPH-d (1,900 pg/l) was previously detected in a grab ground water sample collected from soil boring P-8 at depths between 51 to 55 feet bsg (June 1999). Since May 2000, various BTEX compounds have been detected only in well MW-2 at very low concentrations. With the exception of benzene, concentrations of BTEX have been detected below the California Department of Health Service's (DHS) Maximum Contaminant Levels (MCL) for drinking water frgm wells MWA through MW-4. Benzene has been detected on five separate occasions (Table'), but exceeded the MCL only twice from well MW-2, at concentrations of 6.2 pg/l (August 2000) and 1.5 pg/1 (July 2002). Low concentrations of MTBE have been detected from wells MW-1 and MW-2. MTBE concentrations in well MW-1 have not exceeded primary and secondary MCLs, and MTBE has not been detected in well MW-1 during the last three monitoring events. MTBE concentrations in well MW-2 generally have fluctuated around the primary MCL value of 13 pg/1 (Table 2);the maximum MTBE concentration detected utilizing EPA Method 8260 was 16 pg/l. Low occurrences of 1,2-DCA have consistently�been detected from wells MW-1, MW-2 and MW-4 at concentrations as high as pg/I (Table 2); the 1,2-DCA concentrations detected in water samples at the site were above the MCL of 0.5 pg/l. In the last two quarterly ground water monitoring events(April 2005 and July 2005), 1,2-DCA was detected only in samples from MW-4- at concentrations of 12.0 pg/1 and 2.6 pg/l, respectively. Since September 2001, Iow occurrences of TBA have consistently been detected from well MW-2 at concentrations as high as 48 pg/l,which is slightly above the DHS Action Level (AL) of 12 pg/l; action levels are health-based advisory levels and not enforceable standards. TBA has not been detected in well MW-2 during the last two monitoring events. Laboratory analysis of water samples collected from domestic water wells located at 451 and 452 North Lillian Avenue did not detect any constituents of concern. Advanced GeoEnvironmental,Inc.