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Discussions with the DRMS during the application process indicated that the <br />Division considered the SM -18 mine to be a dry mine site where the likelihood of <br />encountering groundwater was minimal. It was Cotter's understanding that the <br />conventional approach of installing up- and down - gradient wells for these type <br />of mines would provide limited or misleading data. The EPP presented a <br />technical case that showed any potential water encountered during mining <br />would be a perched zone of limited extent making the location and installation of <br />a conventional monitoring well problematic at best. The most likely result of <br />drilling three monitoring wells is that the wells will be dry. This conclusion is <br />supported by drill hole data illustrated by Figures Ul and U2 that showed few <br />moisture zones in the Salt Wash Member. Another consideration is the location <br />of the monitoring well -- especially for a compliance well. For example, with <br />groundwater flow rates of less than a foot per year in the Salt Wash Member of <br />the Morrison Formation and a limited time for the transport of water recently <br />encountered in the mine to migrate into the surrounding rock, a monitoring well <br />would have to be drilled immediately adjacent to the mine workings to detect <br />impacts to groundwater. The approach discussed with DRMS and presented in <br />the EPP would sample any groundwater encountered during mining, determine <br />where the groundwater was coming from, discuss the results with DBMS, and <br />determine the best approach for installing a monitoring well. Based on the <br />results of this phased approach and discussions with the DRMS, additional wells <br />may be warranted. If required by DRMS, Cotter will install additional <br />monitoring wells but the best approach that yields useful data may be something <br />other than conventional monitoring wells drilled from surface. If the purpose of <br />the regulation is to assess the impact of mining activities on the surrounding <br />groundwater, then holes can be drilled from inside the mine into the rock up- <br />and downgradient where groundwater is seeping into the mine, water samples <br />obtained from the subsurface drill holes and groundwater in the mine, and the <br />results submitted to DRMS for evaluation. The alternative approach presented <br />in the EPP and discussed with the DRMS is a technically better approach to <br />7 <br />