SITE INFORMATION AND CORRESPONDENCE

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Mr. Allan Fetters - 2 - 13 June 2007 beneath Ripon Farm Service, it does not rule out the possibility of a fertilizer release at the facility. In the deeper water-bearing zone, both monitoring wells contained about the same concentrations of nitrate, greater than the water quality objective. In the March 2007 off-site monitoring event, all groundwater samples were provided to two different laboratories for analysis. One laboratory, McCampbell, reported consistently lower concentrations than the other laboratory, Excelchem. The higher the nitrate concentration in the samples, the more pronounced the differences in the analytical results were. McCampbell routinely filters all of their samples before analysis in order to protect their instruments, while Excelchem routinely only filters turbid samples unless filtration is specifically requested. While the differences in concentration were large for the highest concentration observed (Exelchem reported 898 mg/I nitrate-as-nitrate in a sample from RMW-3S, whereas McCampbell reported 440 mg/I nitrate-as-nitrate in a sample from this well), the data clearly show that nitrate concentrations are elevated above the 45 mg/I maximum contaminant level in both the shallow and deep water-bearing zones, with the exception of shallow well RMW-1 S-R to the north. In order to remove one element of uncertainty, Ripon Farm Service should request that all samples analyzed for nitrogen be filtered. Groundwater Flow Direction Groundwater surface elevations obtained from the four on-site wells predominately show a westerly direction, varying from west northwest to west southwest, with the August 2006 event showing a slight northern component. The off-site monitoring wells have shown a west- southwest direction and in the most recent event of March 2007, a west northwest direction from three of the four shallow wells. The northern-most off-site well, RMW-1 S-R, showed a water surface elevation that was inconsistent with the water surface elevations of the other off- site wells, and the inclusion of this well in the water surface contour would introduce a southerly component to the west northwest direction shown by the other three wells. Ripon Farm Service should verify the survey elevation and depth measurements of RMW-1 S-R to confirm that the water surface elevation is correct. Currently, the water surface elevations of the off-site monitoring wells are not measured in the same time period as the on-site monitoring wells. Ripon Farm Service needs to make arrangements with the well sampling crews to provide at least one monitoring event each quarter in which the groundwater elevation of the four on-site wells are measured the same day as the off-site shallow wells. Ripon Farm Service should also include groundwater elevation measurements from MW-4 and MW-5, which are two of the shallow on-site monitoring wells that are associated with the underground fuel investigation being conducted on the western portion of the Ripon Farm Service property. In two locations, there is an off-site shallow and deep monitoring well pair. Ripon Farm Service should also calculate the vertical gradient at each monitoring event and list it in the groundwater elevation table.