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f ;rte 15 June 1999 <br /> fi�r. <br /> ='r' E' AGE Project No. 95-0118 <br /> Page 2 of 4 <br /> custody form,placed in a chilled container and transported to McCampbell Analytical, Inc. (MAI) <br /> �_ . in Pacheco, California, a State of California Department of Health Services (DHS)-certified <br /> laboratory. Each sample was analyzed in accordance with the following: <br /> k_a EPA Method"8015 Modified for total petroleum hydrocarbons quantified as gasoline (TPH- <br /> t g) and <br /> EPA Method 8020 for volatile aromatics (benzene, toluene, ethyl benzene and xylenes: <br /> BTEX), methyl tertiary butyl ether(MTBE). <br /> 3.0. FINDINGS <br /> `>= Ground water elevations and flow direction were determined from field measurements,hydrocarbon <br /> impact on ground water was determined by laboratory analysis. <br /> 3.1. RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> The relative ground water elevation in each well was calculated by subtracting the ground water <br /> depth from the surveyed casing elevations. The depth to ground water and the relative ground water <br /> elevationsare summarized in Table 1. During the second quarter sampling event,the depth to ground <br /> water from the casing tops at the site ranged from 30.07 feet to 31.80 feet. The average relative <br /> ground water elevation increased 1.45 feet over the quarter. <br /> During this monitoring event the ground water flow was directed toward the north in the central <br /> f=� portion of the site away from the former UST area. The gradient measured from well MW-3 toward <br /> vapor well VW-3 was 0.0075. Relative ground water elevation contours are illustrated in Figure 3. <br /> ;j <br /> 3.2. ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> J Water samples from monitoring wells MW-2, MW-3 and air-sparging well IAS-2 contained TFH-g <br /> at concentrations of 650 micrograms per liter(,ug/1), 2,000 µg/l and 400µg/l, respectively. <br /> A The samples from wells MW-2 , MW-3 and IAS-2 contained benzene at concentrations of 0.54µg11, <br /> 33 µgll and 3.2µg/l, respectively. Other BTEX compounds were detected at concentrations as great <br /> .;' as 370,ugll (xylene). MTBE was detected only in well MW-2 at a concentration of 15 µg/l. <br /> } Advanced GeoEnvironmental,Inc. <br /> i .: <br /> {'a <br />