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' 26 May 2004 • AGE-NC Project No 96-0229 ' Page 3 of 6 ' 3 1 GROUND WATER ELEVATION AND GRADIENT ' During the August 2003 monitoring event, depths to ground water in wells MW-1 through MW-14 were measured at between 30 96 feet and 33 79 feet below the tops of the well casings (Table 2) Ground water elevations were calculated to be between 18 49 feet(MW-5)and 20 83 feet(MW-12) I below mean sea level(MSL) The ground water surface elevation at the site was within the screened intervals of wells MW-2 through MW-10A,MW-11 and MW-12 but was approximately 15 and 17 feet above the screen intervals (`drowned') in wells MW-1 and MW-10B, respectively, and ' approximately 30 to 87 feet drowned at wells MW-13 (A-D) and MW-14 (A-D) The ground water elevation data for monitoring wells MW-2 through MW-12 during the June 2003 I ground water monitoring event is depicted and contoured in Figure 3, elevation data for deep- screened wells MW-1 and MW-1 OB were not used to determine ground water gradient because these elevations may be representative of deeper ground water conditions The general ground water adient at the site was calculated to be approximately 0 004 ft/ft or less g � � Pp Y > or approximately 21 feet per mile, and inferred to be flowing towards the northeast, further downgradient in the area bound by wells MW-7 through MW-12,the ground water gradient appeared to be much steeper at 0 02 ft/ft or less, or approximately 105 feet per mile I 32 LABORATORY RESULTS OF GROUND WATER SAMPLES A total of twenty-one ground water samples were submitted to McCampbell Analytical Inc (MAI), a DHS-certified laboratory in Pacheco, California ITPH-g was detected in water samples collected from wells MW-1 through MW-7, MW-9,MW-13 (A and D) and MW-14A at concentrations as high as 71,000 micrograms per liter (µg/1) in well MW-2 Various BTEX constituents were detected in ground water samples collected from wells MW-1 through MW-7, MW-9, MW-11, MW-13 (A, B and D) and MW-14A at concentrations as high as 18,000 }tg/l (xylene, MW-6), the highest benzene concentration was detected in sample MW-1 at a concentration of 6,200 �ig/l The fuel additive MTBE was detected by EPA Method 8260B in ground water samples collected from. wells MW-1 through MW-4, MW-6, MW-7, MW-9, MW-10 (A and B) and MW-11 at concentrations as high as 710 µg/1 (MW-6), and 1,2-DCA was detected in samples collected from • Advanced GeoEnvironmental,Inc