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' 07 February 2000 • AGE-NC Project No 95-0144 Page 2 of 4 2 2 COLLECTION OF GROUND WATER SAMPLES 1 The depth to water was remeasured immediately following purging in each well to determine recharge A minimum of 80 percent recharge was observed In each well, except MW-19A,MW-20B and MW-21B immediately after purging Water samples were collected from each purged well using new disposable bailers Samples were transferred into 40-m1 EPA-approved VOA vials containing ' 0 5 ml 18% hydrochloric acid as a sample preservative and into 1-liter amber bottles without preservative The samples were labeled, stored on ice and transported under chain-of-custody to McCampbell Analytical, Inc (MAI), a California Department of Health Services (DHS)-certified ' analytical laboratory Each sample was analyzed for • Total petroleum hydrocarbons quantified as gasoline(TPH-g),diesel (TPH-d) and motor oil ' (TPH-mo) in accordance with EPA Methods 5030/8015m, and • Volatile aromatic hydrocarbons-benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary-butyl ether(MTBE) in accordance with EPA Method 8020/602 Samples collected from wells MW-19A&B,MW-20A&B and MW-21A&B were also analyzed ,for • Volatile organic compounds and fuel oxygenates, di-isopropyl ether (DIPE), ethyl tertiary- butyl ether(ETBE),MTBE,tertiary-amyl methyl ether(TAME) and tertiary butanol (TBA) in accordance with EPA Method 8260 modified 1 ' 3.0. FINDINGS Ground water elevation and flow direction were calculated from field data, hydrocarbon-impact to ground water was inferred from laboratory analysis of the ground water samples ' 31 RELATIVE R WATER ELEVATION AND GRADIENT GROUND ' The elevation of ground water in each well was calculated by subtracting the depth to water from the surveyed casing elevation(Table 1) Between August and November 1999, ground water elevation ' decreased an average of 10 1 feet in monitoring wells MW-19B, MW-20B and MW-21B, screened below a clay layer Ground water elevation decreased an average of 125 feet in the remaining wells The approximate hydraulic gradient for the November 1999 monitoring event was calculated to be ' 0 003 ft/ft with a northerly flow direction Ground water elevation contours derived from data . collected on 08 November 1999 are depicted in Figure 3 Ground water was between approximately 0 1 and 3 5 feet above the screened interval in monitoring wells MW-1, MW-2,MW-4 and MW-13 ' r Advanced Geo Environmental,Inc 1 i '