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Letter to Bryce Romig <br />revision that a cutoff will be installed between Robinson Lake and Eagle <br />Park Reservoir, and that this cutoff will prevent the flow of ground water <br />from Robinson Lake to Eagle Park Reservoir. On October 17, 1995, the <br />Division received drawings and specifications for the proposed cutoff <br />installation, the essential elements of which are a concrete wall, keyed <br />into bedrock, a pump -back system to return ground water intercepted by the <br />concrete wall to Robinson Lake, and a set of alarms and redundant flow <br />return controls. The design of this system is acceptable to the Division, <br />if the following provision is incorporated: The certification of the <br />cutoff will include a statement from the certifying engineer that the <br />concrete wall was keyed into sound, durable, un- fractured bedrock, or that <br />fractures in the bedrock where adequately grouted to prevent ground water <br />flow beneath the concrete cutoff wall. <br />It is clear that the future beneficial use of the ground water between the <br />concrete cutoff wall and Eagle Park Reservoir will be to recharge the <br />reservoir. Given that the purpose of the concrete cutoff wall is to <br />prevent the flow of ground water that could be contaminated by seepage <br />from Robinson Lake into Eagle Park Reservoir, the concrete cutoff wall <br />would be a "protection afforded groundwater quality ". Rule 3.1.7(6)(a) <br />of the Mineral Rules and Regulations requires that points of compliance <br />be established "to evaluate protection afforded groundwater quality ". It <br />is the Division's view that a monitoring well should be established in the <br />non - indurated material beneath the cutoff wall to evaluate its <br />effectiveness, and that numeric protection levels should be established <br />for the monitoring well based on ambient ground water quality. <br />An effort has been made to be comprehensive in the review of your ground <br />water program technical revision, however, it is likely that additional <br />issues will be raised as a result of your responses to this letter or <br />otherwise. Please contact me regarding an extension of the decision date <br />for the technical revision. Please also contact me if you have any <br />questions, or if I may be of any assistance. <br />Sincerely, <br />Allen C. Sorenson <br />Reclamation Specialist <br />C:\WP51\CLIMAXGW.TR <br />-5- November 6, 1995 <br />