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I It ' I ., 26 April 2004' AGE-NC Project No 97-0333 Page 11 of 12 ' s The results from the ground water monitoring and sampling events performed in August 2003 are as follows • Generally, depth to ground water at the site varied between 24 and 26 feet bsg,ground water elevations ranged between 6 46 feet(MW-9E) and 7 95 feet (MW-4) above mean sea level The ground water elevation increased approximately'0 68 feet between August 2003 and the November 2003 ground water monitoring events, the average increase in may be due to seasonal fluctuation, however, the ground water elevation is the lowest documented at the site ' First Zone ground water flow was inferred to be towards a ground water depression in the area of wells EW-1,MW-2,MW-6 and MW-7A at a gradient between 0 003 ft/ft and 0 008 ft/ft (Figure 4) ' Second Zone,Third Zone and Pnmary Aquifer ground water flow was inferred to be towards the south-southwest and south-southeast at approximate gradients of 0'001 ft/ft or less (Figures 5, 6 and 7, respectively) • Due to` the low ground water gradient at the site, small variations in ground water! measurements or changes of recharge/discharge of the local ground water could greatly modify the inferred ground water flow direction • The highest on-site concentrations of dissolved MTBE were detected in the samples collected in the area of First Zone monitoring wells MW-2, MW-6 and MW-7A at ' concentrations as high as 28,000µg/1 Lower concentrations of on-site MTBE were detected I ' in water samples from First,Second,Third and Primary Aquifer Zone monitoring wells MW- ' ;I 1, MW-3, MW-7 (B-E) and MW-8 (A and C), generally, moderate to significant MTBE f increases were reported this quarter from most of the on-site wells(Figures 8 and 9,Table 3) • Off-site MTBE was reported only in the water sample from Second Zone monitoring well MW-1213 at a concentration of 30 µg11 I I • Concentrations of PCE and/or TCE have been detected in water samples collected from all ' well locations associated with the Rainwater Car Wash investigation Minor to significant PCE and)or TCE concentrations were detected in 39 of 47 ground water monitoring wells located in First Zone, Second Zone,Third Zone and Primary Aquifer Zone Aquifers (Figure ' '10, Table 4) The highest concentrations of dissolved PCE were detected in the samples collected in the area of on-site well MW-10B(upper Second Zone),and offsite well MW-12A (First Zone) at concentrations as high as 1,400 µg/1 ' I I i • PCE and TCE are chlorinated solvents often associated;with dry cleaning operations Based on a August 2003 PCE iso-concentration map I iii First Zone water (Figure 10), AGE ' finterpre'ts the PCE/TCE-plume to have originated from the dry cleaner's facility located I 'immediately east of the Rainwater Car Wash SII ' I ' ' f AdvaiseedGeoEnvironmental,Inc i t ,IC