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r � <br /> Pombo Ranch Property <br /> Fourth Quarter Groundwater Sampling Report October 2004 <br /> Page: 2 <br /> 0.4 to 1.1 feet higher than levels recorded in the July 14, 2004 event. Shallow <br /> groundwater flow was to the Northeast with a flat gradient (N54E / 0.0006), similar to the <br /> groundwater flow observed in previous events. A very slight downward vertical gradient <br /> was observed at the well pair MW5 and MW105. Wellhead elevations, depth to water <br /> measurements, and groundwater elevations are shown below. Groundwater elevations and <br /> flow direction are located on figure 2. Cumulative groundwater elevations are shown on a <br /> hydrograph in figure 6. <br /> Groundwater Elevations 10/20/04 <br /> Well jCollar Elevation DTW GW Elevation <br /> MW-1 53.47 9.46 44.01 <br /> MW-2 53.22 9.47 43.75 <br /> MW-3 55.02 10.08 44.94 <br /> MW-4 53.55 9.56 43.99 <br /> MW-5 53.46 9.68 43.78 <br /> MW-105 53.55 10.03 43.52 <br /> Gasoline petroleum and volatile aromatic hydrocarbons were detected at very low 05` <br /> concentrations in wells MW1, MW2, MW4 and MW5 located at and immediate down <br /> gradient from the former underground storage tanks. Fuel oxygenates were detected at <br /> very low concentrations in wells MW4. Laboratory analyses are shown below and on <br /> Figures 3 and 4. <br /> Laboratory.Groundwater Sam le Results 10/20/04 <br /> Sam le I.D. Gasoline Benzene Toluene E-Benzene Xylenes Oxygenates Dissolved 02 <br /> MW-1 0.07 0.9 12 1.1 5.5 ND 0.92 <br /> MW-2 0.10 1.0 18 2.1 9.8 ND 0.80 <br /> MW-3 <0.05 <0.3 <0.3 <0.3 <0.6 ND 0.85 <br /> MW4 0.30 2.5 <0.3 9.3 6.3 29 mtbe 0.60 <br /> MW-5 1.0 2.3 20 16 16 ND 0.98 <br /> MW-105 10.12 1 0.8 1 18 1 2.5 12 ND 1.43 <br /> ND=Non Detect NA=Not Analyzed <br /> Mg/L for gasoline&DO µglL for BTEX,MTBE,and 8260 Oxygenated Compounds <br /> Dissolved oxygen measurements were collected as part of the groundwater monitoring to <br /> provide an estimate of the level of biologic activity in the groundwater. The dissolved <br /> oxygen was measured during this monitoring event in the field (and noted on the field <br /> logs), using a down hole meter. Dissolved oxygen concentrations are presented in the <br /> above table and in figure 5. <br />