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�OF�O\. DEPARTMENT OF NATURAL RESOURCES <br /> o! DIVISION OF WATER RESOURCES <br /> -, I <br /> John W.Hxckenlooper <br /> 187 j Governor <br /> August 7, 2012 Exec King <br /> g Executive Director <br /> Dick Wolfe,P.E. <br /> Director/State Engineer <br /> DEERE & AULT CONSULTANTS, INC David L.Nettles,P.E. <br /> DEREK FOSTER, P.E. Division Engineer <br /> 600 S. AIRPORT ROAD, BLDG A, STE 205 <br /> LONGMONT, CO 80503 <br /> RE: SLURRY WALL LINER APPROVAL - PROVISIONAL <br /> STAGECOACH PIT, DRMS M-1983-067 (WDID 0203015) <br /> S26/35-T1S-R67W, WATER DIVISION 1, WATER DISTRICT 2 <br /> Dear Derek: <br /> The purpose of this letter is to provisionally approve the lining of the Stagecoach Pit. This liner is <br /> located in the S'YzSWSW of Section 26 and the E/SWNW and the NWNW of Section 35, all in <br /> Township 1 South, Range 67 West of the 6"' P.M. and is a part of the Stagecoach Pit (DRMS M-1983- <br /> 067). There is active mining occurring within the liner boundary with future mining to occur in the <br /> southern portion of the liner boundary. The slurry wall liner leak test commenced March 26, 2012 and <br /> concluded on July 2, 2012. A site inspection was performed by our office on March 28, 2012 to <br /> review site conditions and the leak test plan. <br /> Your report dated July 27, 2012 provides the liner summary and leak test result. The test data <br /> provided indicates that the liner meets the design standard referenced in the August 1999 State <br /> Engineer Guidelines for Lining Criteria for Gravel Pits (1999 SEO Guidelines). Meeting the design <br /> standard requires that during reservoir operations all water inflows and outflows for the liner perimeter <br /> enclosed area be accounted for on a monthly basis. <br /> This liner approval is applicable only during mining operations at the site and does not classify the <br /> structure as a reservoir capable of water storage. However, for the remainder of mining operations, <br /> water within the liner boundary is now classified as trapped native ground water. The trapped native <br /> ground water may be removed from within the lined area and returned to the stream system through <br /> surface flow or ground water recharge without the need for replacement so long as the operator does <br /> not put the water to beneficial use. All native trapped ground water remaining that is put to beneficial <br /> use (except for the water removed in product) must be replaced by the operator. All inflow of water <br /> into the liner boundary from any source, including precipitation and ground water inflows shall be <br /> removed by the pit operator so as not to cause out-of-priority storage. In order for the liner to be <br /> approved for water storage the operator must perform a final leak test once mining is complete <br /> and the site is at final grade. The final leak test will be allowed to have a modified duration of <br /> 30-days as long as the liner continues to satisfactorily operate during mining operations. <br /> Please contact me at the number below if you have any questions. <br /> Sincerely, <br /> Jona an 1. er ez, P.E. <br /> Water Resource Engineer <br /> ec. William Schneider, District 2 Water Commissioner(Williarn.Schneider(a.state.co.us) <br /> WDID File(0203015) <br /> Water Division 1 • Greeley <br /> 810 911,Street,Suite 200•Greeley,CO 80631 •Phone:970-352-8712•Fax:970-392-1816 <br /> www.water.state.coms <br />