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' 18 November 1998 <br /> AGE-NC Project No 95-0143 <br />' Page 2 of 4 <br /> 2 2 COLLECTION OF GROUND WATER SAMPLES <br /> Water samples were collected from each well using new,disposable bailers and,upon retrieval, were <br /> transferred into 40-m1 EPA-approved VOA vials containing 0 5 ml 18% hydrochloric acid as a <br /> sample preservative The samples were labeled and transported under chain-of-custody, In a chilled <br /> container, to McCampbell Analytical, Inc (MAI), a California Department of Health Services <br /> (DHS)-certified analytical laboratory in Pacheco, California The samples were analyzed for <br /> • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA <br />' Method 5030/8015 <br /> Volatile aromatic compounds (benzene, toluene, ethylbenzene and xylenes BTE&X) with <br /> methyl tertiary-butyl ether (MTBE) in accordance with EPA Method 602, and <br /> • Volatile organic compounds with oxygenated compounds (di-Isopropyl ether [DIPE], ethyl <br /> tert-butyl ether [ETBE], MTBE, tert-amyl methyl ether [TAME] and tert-butanol [TBA]) in <br /> accordance with EPA Method 8260 <br /> Due to breakage of sample containers during shipping to the laboratory, the sample collected from <br />' MW-3 could not be analyzed for volatile organic compounds with oxygenated compounds <br /> 3.0. FINDINGS <br /> 1 3 1 GROUND WATER ELEVATION AND GRADIENT <br /> The elevation of ground water in each well was calculated by subtracting the depth to water from <br /> 1 the surveyed casing elevation(Table 1) Ground water elevations decreased an average of 0 53 feet <br /> between May and August 1998 Ground water was above the screened interval of all wells at the site <br /> from almost one foot above the screened interval in MW-17 to nearly nine feet above the screened <br />' interval in MW-3 The approximate hydraulic gradient was calculated to be 0 001 ft/ft with a <br /> northeasterly flow direction on the subject property However, a steeper gradient of 0 003 ft/ft was <br /> measured north of the site with a northerly flow direction Ground water elevation contours for the <br />' August 1998 monitoring event are Illustrated in Figure 3 <br />' 32 ANALYTICAL RESULTS OF WATER SAMPLES <br />' During the May 1998 monitoring event, TPH-g was detected at concentrations of 180,000 parts per <br /> billion(ppb,reported as micrograms per liter),2,100 ppb,2,400 ppb and 34,000 ppb In samples from <br /> . MW-3,MW-6,MW-7 and MW-9,respectively BTE&X compounds were detected in samples from <br /> Advanced GeoEnvironmental,Inc <br />