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. 31 January 2000 AGE-NC Project No 95-0184 ' Page 2 of 4 t ' 22 COLLECTION OF GROUND WATER SAMPLES Water samples were collected from each purged well using new disposable bailers Each sample was ' transferred into 40-m1 EPA-approved VOA vials containing 0 5 ml. 18% hydrochlonc acid as a E sample preservative The sample from'MW-4 was also transferred into a 1-liter amber bottle without ' preservative The sample containers were labeled,placed in a chilled container and transported under ' chain-of-custody to McCampbell Analytical, Inc (MAI) in Pacheco, California, a California Department of Health Services (DHS)-certified analytical laboratory The samples were analyzed ' for • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA ' Method 5030/8015m • Volatile aromatic hydrocarbons (benzene, toluene, ethylbenzene and xc lenes, BTEX) with methyl ternary-butyl ether (MTBE) in accordance with EPA Method 602/8020 and I • Volatile organic compounds and fuel oxygenates (di-isopropyl ether [DIFF], ethyl tertiary- butyl ether [ETBE], tertiary-amyl methyl ether [TAME] tertiary butanol [TBA] and MTBE) In accordance with EPA Method 8260 i ' The sample from MW-4 was also analyzed for total petroleum hydrocarbons quantified as diesel (TPH-d) in accordance with EPA Method 8015m ' 30 FINDINGS 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT i The average depth to ground water at the site was 31 80 feet below the well casing tops during the ' Nox ember 1999 monitoring eN ent Ground water elevation decreased an average of 1 34 feet between August and November 1999, Ground water was approximately 22 to 23 feet above the screened interval in monitonng wells MW-1, MW-2 and MW-3 Ground water was approximately I13 feet above the screened interval in MW-4, VW-2B and VW5C, 7 9 feet above the screen in MW-, 7, 3 5 feet above the screen in VW-3 and 1 6 feet above the screen In VW-4 Ground water was v.ithin the screened interval of well VW-513 only Ground water elevations in deeper wells were slightly lower than elevations calculated for the shallower 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 elevation and flow direction Measurable free product was not encountered at the site during the November 1999 monitoring event For hydraulic gradient determination, the wells were divided into two data sets, MW-1, MW-2 and E 4d),ancid CIUEmir.ental laic