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1 i Ripona Market July 2006 Third Quarter Groundwater Sampling Report Page: 2 1 Groundwater flow direction was flat with a very shallow��gradient (North 60 East 10.0028 j similar to past monitoring events. The groundwater elevations and groundwater flow direction are shown on Figure 2. Site Map / Groundwater Flow. A very slight vertical -'' component of groundwater now (upward 0.0001 Ft/Ft) was observed at the deep 1 shallow well pair MW2 /MW4. Groundwater Elevations 07113/,06 Well Collar Elevation DTW !j GW Elevation MW-1 63.28 21.78 141.5 MW-2 63.59 21.99 141.6 MW-3 63.80 22.29 41.51 i MW-4 63.52 21.98 '1141.54 a MW-5 163.18 121.71 1 141-47 1i The analytical laboratory did not report detectable concentrations of petroleum and jr aromatic hydrocarbons or MTBE in waters sample collected from the monitoring wells. Groundwater chemistry for the July 13, 2006 event iah presented in Figure 3. A slight oxygen low is present at MW2 with higher oxygen concentrations measured in the other wells. Dissolved oxygen distribution for the July 13, 2006 event is shown in Figure 4. Laboratory Groundwater Sam le Results Petroleum Com ounds 0711310 Sample I.D. Gasoline Benzene .Toluene E-Benzene X lentis MTBE t-Butanol 1,2DCA DO MW-1 <0.05 <0.3 <0.3 <0.3 <0.6 M <0.5 <5 <0.5 - MW-2 <0.05 <0.3 <0.3 <0.3 <0.6 ;j <0.5 <5 <0.5 3.43 MW-3 <0.05 <0.3 <0.3 <0.3 <0.6 ;j <0.5 <5 <0.5 4.43 MW-4 <0.05 <0.3 <0.3 <0.3 <0.6 M - 0.5 <5 <0.5 3.43 MW-5 <0.05 <0.3 <0.3 <0.3 1.2 X0.5 <5 <0.5 3.83 ND=Non Detect NA=Not Analyzed j Mg/L for gasoline&Dissolved Oxygen µg(L for BTEX,MTBE,and 8260 Oxygenated Compounds r The lateral and vertical extent of MTBE, the contamiant of concern has been defined laterally and vertically to be restricted to the immediate vicinity of the former F i underground storage tanks. Similar fluctuations in water level]and previous detections of low concentrations of MTBE indicate that the deep well�MW-4 is in communication with the shallow well MW-2, h I j A comparison of MTBE concentrations detected in monitoring well MW-2, located in the vicinity of the former underground storage tanks, indicates that MTBE concentrations show a decrease from greater than 2000 ug/1 to below the laboratory detection limit of 0.5 ug/l. The chart shows clearly shows a decrease in oxygen content associated with the decrease of MTBE content followed by a rebound rin oxygen content and MTBE concentrations dropping to non-detectable. A chart of MTBE and dissolved oxygen ; concentrations and groundwater elevations is site is presented in Figure 6.