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x 1 } tt 7 t '1' t ' , I_ � _ x -. -e -. y - - "` i - _r 1 r _ n x i 11`J �- �L • ' I � c ' � ' t h i t t 7 l . 10 April 2001 AGE-NC Project No '96-0235 's Page 2 of 5 F 2 2 COLLECTION OF GROUND WATER SAMPLES Water samples were collected from each purged well using new disposable plastic bailers Each- ' t - water sample was transferred into 40-ml VOA vials containing 0 5 ml 18% hydrochloric acrd as a sample preservative and into 1-liter amber bottles without preservative After collection,the samples were properly labeled, placed in a chilled container and transported under chain-of-custody to - ' McCampbell Analytical, Inc (MAI), a State of California Department of Health Services (DHS)- certified analytical laboratory, and were analyzed for f 1 ` • Total petroleum'hydrocarbons quantified as gasoline'(TPH-g) and as diesel (TPH'd) in accordance with EPA Methods 5030/8015 and 3550/8015, respectively, ' • Volatile aromatic hydrocarbons - benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary-butyl ether (MTBE) in accordance with EPA Method 602/8020, and for • Fuel oxygenates - di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), MTBE, L ' tertiary-amyl methyl ether (TANTE), tertiary butanol (TBA), methanol, ethanol, ethylene chbromide(EDB) and 1,2-dichloro ethane(1,2-DCA) in accordance with EPA Method 8260 Modified - ' 3.0. FINDINGS Ground water elevation and flow direction were mferred from field data, hydrocarbon`impact to ' ground water was quantified by laboratiory analysis of the ground water samples Field observations, resultslof laboratory analysis of groundwater samples,and a discussion of data collected during field work follows ' f ' ' 3 1 GROUND WATER GRADIENT AND FLOW DIRECTION i - --The casing elevation of each well was previously surveyed relative to a City of Stockton bench mark -- ' The elevation of ground water in each well was calculated by subtracting the depth to ground water from the surveyed casing elevations (Table 1) Depths to ground water,ranged from 15 02 feet to '18 04 feet below the tops of the well casings Ground water elevations at the site ranged from-9 87 ' feet in MW--6A to -11 50 feet mean sea level (MSL) in MW-2 Groundwater elevation increased r an average of 1 86 feet in the wells MW4 was not monitored during the 13 March 2001 event due to construction activity in the area of the well . 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 21 96 and 24 12 feet above the Advanced GeoEnvironmenta4 Inc I { r M