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<br />Ivtemo to Wallace Erickson 7 Mav 3 2001 <br />It is stated in the Applicant's analysis (revised Exhibit G received 3/20/01) that drawdown in the <br />Robinson Well of less than 10 feet is acceptable and that drawdown of less than 2 feet is insignificant. <br />This statement by the Applicant is based on the notion that the Robinson Well penetrates 60 feet of <br />water yielding alluvial sand and gravel. Tltis notion is taken from State Engineer's records that indicate <br />a well depth of 65 feet and a water level in the well at five (5) feet below ground surface. if the entire <br />length of the Robinson Well below the water table is drilled into water yielding formation, DMG would <br />agree with the Applicant's statements regarding significant and acceptable drawdowns, in that a ten foot <br />drawdown would only reduce the wells yield by approximately one-sixth. However, given that the <br />Applicant represents that the depth to bedrock in the pit area is on the order of 20 feet (revised Exhibit <br />D received 3/20/01), it seems unlikely that the depth to bedrock at the Robinson Well is as much as 121 <br />feet, which the Applicant's analysis assumes. It is possible that the Robinson well was drilled through <br />twenty feet (more or less) of alluvium, then continued to a total depth of 65 feet in bedrock. This well <br />drilling strategy may not provide significantly greater yield, but may have been done to provide <br />additional in-bore storage of water. The following diagram is illustrative. <br />If the Robinson Well is in fact configured similarly to the above diagram, a ten foot drawdown in the <br />well could diminish the well yield to one-third of its current value. The Applicant has stated in a <br />telephone conference that the owners of the Robinson Well represent the borehole to be completed in <br />alluvium through its entire depth, which would make drawdown less of a concern. Without the <br />