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n•w1y ) Y ' 04 February 2004 AGE-NC Project No 98-0534 ' Page 2 of 3 ' 2 2 COLLECTION AND ANALYSIS OF GROUND WATER SAMPLES ti After the depth to ground water was measured to ensure that a minimum of 80% well-volume ' ' recharge had been achieved, a'water sample was collected from each well using a dedicated and disposable plastic bailer Immediately upon retrieval,samples were transferred Into one-liter amber bottles and three 40-m1 EPA-approved volatile organic analysis(VOA)vials containing 0 5 ml 18% hydrochloric acid as a sample preservative The samples were logged on a chain-of-custody form, stored in a chilled container under ice The samples were later transported under chain-of-custody to Cal Tech Environmental Laboratory(CTEL), State of California Department of Health Services ' (DHS)-certified analytical laboratory# 2424 for analysis The samples were analyzed for • Total petroleum hydrocarbons quantified as gasoline (TPH-g) and diesel (TPH-d) in ' accordance with EPA Method 8015 Modified, • Benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary-butyl ether ' (MTBE) in accordance with EPA Method 8021, and • Oxygenated compounds - di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), MTBE,tertiary-amyl methyl ether(TAME),tertiary butanol(TBA),ethanol,methanol, 1,2- dibromoethane (EDB) and 1,2-dichloroethane(1,2-DCA) in accordance with EPA Method 8260-Modified 3.0. FINDINGS ' Ground water elevation, flow direction and gradient were determined from field data collected on ' 31 October 2003, the contaminant impact to ground water was assessed from the laboratory data ' 3 1 GROUND WATER ELEVATION AND GRADIENT The relative elevation of ground water in each well was calculated by subtracting the depth to ground ' water from the relative casing elevation(Table 1) The average depth to ground water on 31 October was 12 5 feet below the tops of the well casings,presently the water table is at the top of the screened interval of the wells Ground water was inferred to be flowing towards the south west across the former UST area to 0 002 (see Figure 3) The ground water elevation of monitoring well MW-4 appeared anomalously low,out of the range of the surrounding wells by 1 foot,and therefore the data from that well was not used to map the ground water elevation Advanced GeoEnvironmental,Inc