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Paul Banks May 13, 2004 Page 3 reductions to values that would equate to transmissivities in the range of 40,000 to 60,000 gpd/ft provided a better match with respect to water table gradient. The specific yield value of 0.20 was found to be an insensitive pazameter and was varied between 0.18 and 0.22 during our simulations. These values are within the normal expected range for unconsolidated sands and gravels. The results of the modeling work indicate that the mining operations, and under the assumptions included in the model, will potentially have an impact on the water table local to the mine property and, to a lesser degree, across the alluvial valley to the north to the vicinity of the Excelsior ditch. Simulating mining and dewatering along a 1000-foot wide swath along the entire northern portion of the mine property, drawdowns of 5 to 8 feet were predicted for the azea north of the mine in the vicinity of the Evans wells, while 2 to 4 feet of drawdown was predicted for the area across the valley where the Excelsior ditch is located. The impacts of these predicted drawdowns on the wells and the ditch can be assessed via additional considerations. With respect to the ditch, the concern has been that lowering of the water table in the ditch vicinity could increase the leakage out of the unlined structure. However, visual observations of the ditch last February, when it was not flowing, clearly indicated that the ambient non-irrigation season water table lies below the bottom of the ditch. Figure 3 is a photograph of the ditch taken at that time, and shows that there is no water standing in the bottom of the ditch, as would be the case if the water table were higher. Given this condition, it is clear that any changes in the local water table resulting from the mining operations cannot have any impact on the ditch leakage, as the phenomena referred to as the "hydraulic break" has already occurred. This means that there is no d]rect hydraulic connection between the water level, or stage, in the ditch and the local water table and thus altering the water table below the bottom of the ditch cannot affect the ditch leakage rate, which has already achieved its maximum. This can be better understood by considering the opposite case whereby the ambient water table lies just below the level of the stage in the ditch. In this case, there will be some net ditch loss governed by the minimal head differential between the ditch stage and the water table elevation. As the water table elevation is lowered, the head differential increases, thus driving more water out through the bottom of the ditch. However, there is a limit here. Once the water table lowers to the level of the bottom of the ditch, the differential has reached its maximum and any further lowering will hydraulically disconnect the two and cannot increase the rate of leakage from the ditch at that point. Thus, the mining operations and any change in the water table resulting from the associated dewatering operations cannot have any impact on the flows in the Excelsior ditch. A further consideration here is the question of whether or not the surficial clays, as noted at the mine property also exist along this reach of the ditch, which, if such were the case, further reduce any possibility of a mine related impact on the ditch. With respect to the Evans wells, the model predicted, as noted above, drawdowns in the range of 5 to 8 feet. To better assess what impact this might have on the ability to pump the wells; an additional analysis was carried out. In this case, a pump test analysis and well simulation program, Agtesolve, was utilized in determining how the lowering of the water table dlartir~ attd lhood Wq[er Causultartts, lrm.