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' 06 April 1998 • AGE-NC Project No 95-0184 ' Page 2 of 4 Preservative The samples were labeled,placed in a chilled container and transported under chain-of- custody to McCampbell Analytical, Inc (MAI) in Pacheco, California The samples were analyzed in accordance with EPA Method 5030/8015m for total petroleum hydrocarbons quantified as ' gasoline (TPH-g), in accordance with EPA Method 602/8020 for volatile aromatics hydrocarbons (benzene,toluene,ethylbenzene and xylenes,BTE&X)with methyl tertiary-butyl ether(MTBE)and in accordance with EPA Method 8260 for volatile organic compounds and oxygenated compounds ' The sample from MW-4 was also analyzed in accordance with EPA Method 8015m for total petroleum hydrocarbons quantified as diesel (TPH-d) 3.0. FINDINGS 1 ' 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT The average depth to ground water at the site was 38 69 feet below the well casing tops during the January 1998 monitoring event Ground water elevation increased an average of 1 0 feet between October 1997 and January 1998 Ground water was approximately 16 feet above the screened • interval in monitoring wells MW-1, MW-2 and MW-3 Ground water elevations in these wells were similar to elevations measured in surrounding wells at the site Vapor well VW-5 was installed at an angle of approximately 15° from vertical and therefore was not used for calculating the ground water flow direction The inferred ground water flow direction in January 1998 was generally toward the east with a gradient of approximately 0 002 ft/ft (Figure 3) The gradient was more steep toward the western side of the site Free product with a thickness of less than 0 01 feet was measured in VW-213, VW--3 and VW-5C with the interface probe during the January 1998 monitoring event, traces of product were noted in well MW-4 during purging 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES TPH-g was detected in each well sampled, with concentrations as high as 170,000µg/1 (micrograms per liter, equivalent to parts per billion, ppb) Benzene was detected at concentrations as high as 38,000 ppb TPH-d was detected in the sample from MW-4 at a concentration of 9,100 ppb Di- isopropyl ether(DIPS)was detected in the sample from MW-3 at a concentration of 5 4 ppb MTBE was detected in samples collected from VW-2B, VW-3, VW-4 and VW-5B at concentrations of 1,300 ppb, 1,400 ppb, 1,200 ppb and 280 ppb, respectively 1,2-Dichloroethane (DCA)was detected in the samples from MW-1, MW-2 and MW-3 at concentrations of 14 ppb, 25 ppb and 9 7 ppb, respectively Eleven additional constituents were detected with EPA Method 8260 at concentrations as high as 7,400 ppb (1,2,4-tnmethylbenzene, MW-4) Analytical results are summarized on Tables IAdvanced GeoEnveronmental,Inc 1 ,