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• 13 April 1998 <br /> AGE-NC Project No 95-0143 <br />' Page 2 of 4 <br />' container,to McCampbell Analytical,Inc (MAI) in Pacheco, California The samples were analyzed <br /> for <br />' • total petroleum hydrocarbons quantified as gasoline (TPH-g) by EPA Method 5030/8015 <br /> modified <br />' • volatile aromatic compounds (benzene, toluene, ethylbenzene and xylenes BTE&X) in <br /> accordance with EPA Method 602, and <br /> • volatile organic compounds with oxygenated compounds in accordance with El'A Method <br />' 8260 <br /> F <br /> 30 FINDINGS <br /> 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> The relative elevation of ground water in each well was calculated by subtracting the depth to water <br /> from the surveyed casing elex ation (Table 1) Ground water elevation increased an average of 2 87 <br /> feet between November 1997 and February 1998 Ground water was approximately seven feet above <br /> the Screened interval in MW-3 and MW-9, appioxzmately four feet above the screened interval in <br /> MW-6 and MW-7 and approximately one foot above the screened interval in MW-10 and MW-14 <br /> Giound water was near the top of the screened interval for MW-15 and MW-16 and within the <br /> screened interval in MW-17 The approximate hydraulic gradient was calculated to be 0 0059 ft/ft <br /> with a northerly flow direction north of the site Ho\Never a shallower gradient of 0 0025 ft/ft was <br /> measured on the subject property with a northeasterly flow direction Relative ground water <br />' elevation contours for the Febivary 1998 monitoring event are illustrated in Figure 3 <br />' .32 ANALYTICAL RESULTS OF WATER SAMPLES <br /> During the Febivaiy 1998 momtoung event, TPH-g was detected at concentrations of 180,000 parts <br /> per billion (ppb, ieported as micrograms per Mer), 470 ppb, 5,100 ppb, 41,000 ppb and 550 ppb, in <br /> samples fiom MW-3, MW-6, MW-7, MW-9 and MW-14, respectively BTEkX compounds were <br /> detected in samples fiom the same wells at concentrations as high as 54 000 ppb (toluene in the <br /> sample fiom MW-3) <br /> 7Action <br /> yl benzene was detected in MW-7 at a concentration of 58 ppb, above the State of Cahforn�Level (AL) of 45 ppb 1,2-Dichloroethane (1,2-DCA) was detected in MW-14 at a <br /> ntration of 16 ppb, above the State of Calzfoinia Maximum Contaminant Level (MCL) of 0 5 <br /> ------ <br /> -._�.-- <br /> Affranced GeoEnr ironmcnta4,Inc <br />