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• Lockable Ca <br />2" DR-11 HDPE <br />Non-Shrink G <br />GrcAe Une- (02.375" Bore <br />Mineral Topsoil <br />t -A <br />Gravely, NEW1.1 <br />Unconsolidated Soll-1, <br />Moderately <br />Weathered Bedrock : <br />Slightl <br />Weathered Bedroc <br />• Bedrock = <br />Perforated, 3/16° Dla„ III =1I <br />Spaced 4 Colunn5, II <br />V Annular Rows <br />Monltoring Well <br />Constructlon <br />The EPA currently is doing extensive monitoring of ground water sources (as stated earlier, The Big Five Tunnel <br />drainage is monitored, collected, and pumped to the Argo Tunnel Treatment Facility located in Idaho Springs). <br />As a part of normal mill operations, mill process water will be continuously monitored. A pH monitor and data <br />recorder will be installed at the tailings pump location within the mill. Should the pH reach a state outside of the <br />7.5-9 range that is necessary to precipitate the heavy metals, alarm notification will be activated for the operations <br />personnel. The submittal notes on this Serfilco Model 432 monitor/recorder can be found attached in this Exhibit C. <br />If the pH falls outside of the 7.5-9 range, the operators are instructed to shut down the operation that delivers waste <br />to the impoundment. Once the source of the problem is corrected upstream in the process, waste can then be <br />continued to be discharged to the impoundment. <br />It is practically impossible for heavy metals to be in solution under these operating conditions (pH range of 7.5-9) as <br />shown in the attached A Water Handbook for Metal M:ining_Operations, by Thomas R. Wildeman. <br />There are no known domestic wells or springs downgradient of the site (reference CO Div. of Water Resources map <br />• attached). Groundwater flow beneath the site is controlled by mine openings as discussed above in 6.3.3(1)(i). <br />Page 7 of 35