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Mc JeffKel]er <br />March 6, 2006 <br />Page 2 <br />With respect to the background figure, it is important to recognize that the map includes the <br />locations of the slurry wall lined pits from the previous modeling, both those proposed by Asphalt <br />Paving and those for the proposed Westminster storage pits to the south. These outlines were added <br />to the base map for the prior modeling and it seemed most eflicient for purposes of this report not to <br />have to prepaze a separate base map excluding the slurry wall locations. <br />As can readily be determined from the Figures, the drawdown impacts from the Phase I <br />dewatering will be minimal Some three-plus feet of drawdown is observed at the east edge of the <br />Phase I area that then decreases rapidly as one moves to the east. At the WIA well site, the <br />predicted drawdown is considerably less than 0.5-foot. <br />The second simulation run, as noted above, incorporated the Phase II and I[I sluny wall. <br />Figures 3 and 4 present the predicted drawdown contours for this configuration. As would be <br />expected, the presence of the large impermeable barrier immediately east of the Phase I area <br />essentially removes any impacts from the Phase I pit. The contours to the south of the slurry wall <br />azea are negative and reflect the slight mounding that is predicted to occur along the upstream edge <br />of the slurry wall azea. Similazly, the contour line that extends out north of the WIA well represents <br />a minimal drawdown imposed from the downstream shadowing impacts of the slurry wall. <br />Based on the results of the modeling carried out, it is our opinion that the Phase I dewatering <br />and mining will have no significant impacts on the surrounding water table conditions, especially if <br />the Phase lI and III slurry wall is installed prior to the completion of the phase I mining. In a highly <br />transmissive aquifer as exists at Wattenberg, the slight drawdowns predicted are, in our opinion, <br />extremely unlikely to have any measurable effect on the ability of alluvial wells in the area to <br />continue to pump as would be the case absent the Phase I mine operations. <br />Please let us know if you have any questions concerning the modeling carried out or the <br />contents of the letter report. We appreciate the opportunity to have been of service to you on this <br />project. <br />Sincerely, <br />~/ <br />i~~~ <br />ippe L. Martin, C.P.G. <br />Vice President <br />cc: Mr. Paul Banks w/enc <br />Martin and Waod Water Consu{tarits, Inc. <br />