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y A� 1 29 December 2000 AGE-NC Project No 96-0235 Page 5 of 8 r3.0. FINDINGS Ground water elevation and flow direction were inferred from field data, hydrocarbon.-Impact to r ground water and soil was quantified by laboratory analysis of the ground water samples Field ,observations, results of laboratory analysis of ground water samples and_a discussion of data collected during field work follows r 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION r Thelevation f ch well was previously surveyed relative to a CIt of Stockton benchmark The casing o ea p y y y The elevation of ground water in each well was calculated by subtracting the depth to ground water " rfrom the surveyed casing elevations (Table 1) Depths to ground water ranged from 15 12 feet to 17 61 feet below the tops of the well casings Ground water elevations at the site ranged from--9 57 r feet in MW-7 to — 11 13 feet mean sea level (MSL) in MW-2 Ground water elevation increased an average of 1 50 feet in the wells installed prior to July 2000 To infer ground water flow direction, the ground water elevation data was divided into two sets based on the well screen intervals Ground water was between 22 4 and 24 8 feet above the screened intervals in monitoring wells MW-1, MW-2, MW-6B, MW-813 and MW-9 comprising the deeper r water data set Ground water was within the screened intervals for monitoring wells MW-4, MW-5, MW-6A, MW-7, MW-8A and MW-10 and was approximately 12 5 feet above the screened interval in MW-3, comprising the shallow water data set Figure 3 illustrates the ground water elevations r based on the two data sets Ground water flow direction was calculated to be toward the southwest using data from wells screened within the lower interval Ground water elevations, based upon data from the shallow wells indicate a radial flow varying from the northwest to north to northeast 3 2 ANALYTICAL RESULTS OF WATER SAMPLES TPH-g was detected in the samples collected from MW-1,MW-2, MW-9,MW-10,MW-11 B,EW-1 and EW-2 at concentrations as high as 73,000 inicrograr s per liter (µg/1) .TPH-d was detected in rMW-1, MW-2, MW-3, MW-9, MW-10, MW-11B, MW-12B, EW-1'and EW-2 at concentrations as high as 14,000 µg/1 BTEX compounds were detected in samples from six wells at concentrations as high as 4,400 µg/1, 17,000 µg/l, 2,400 �Lg/l and 12,000 µg/l, respectively MTBE was detected in the water samples collected from MW-3,MW-4,MW-9, MW-10, MW-11 B, MW-12B, MW-13A, MW-13B and EW-1 at concentrations ranging from 1 6 lig/lto 180 µg/1 TBA was detected in water samples from MW-6B and MWl l B at concentrations of 22'µg/1 and 14 gg/l, . respectively Other oxygenates were not detected during the July and August 2000 monitoring r Advanced GeoEnvironmentsi,Inc r r