2013-05-22_REVISION - M2004031 - Laserfiche WebLink

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RECEIVED ✓MAY ? ? ?013 May 21, 2013 DIV1" OF RECI.Al90 MINING AND SAFM Mr. Berhan Keffelew ✓ Division of Reclamation Mining and Safety 1313 Sherman Street, Room 215 Denver, CO 80203 AGGREGATE INDUSTRIES Re: Permit Number M- 2004 -031— Hazeltine Mine /technical Revision Request Regarding Water on Neighboring Property Dear Mr. Keffelew: This letter is submitted as a summary of our telephone conversation of this date regarding your questions relative to Aggregate Industries' technical revision request of April 30, 2013. As we discussed, there are no additional reclamation costs associated with the alternative surface drainage system proposed in the April 30 revision request. Surface water will be gravity fed, not pumped, to the agri-drain to be installed on the east side of the excavated mine. The agri-drain will be set to adjust the water drainage to establish pre- mining surface conditions on the neighboring Orr property. As the system proposed is for drainage and control of surface water elevation to reduce surface water levels to pre- mising conditions, and does not involve pumping of groundwater, an amendment to AI's substitute water supply plan and/or well permit is not necessary. The elevation of the pipe section from the agri-drain through the slurry wall will be surveyed in to provide for pipe installation/slurry wall breach above the reservoir spillway structure elevation, with the intent of leaving the pipe in as a long -term, post - mining solution to the neighbor water issue. Water coming into the reservoir via the pipe post - mining will be monitored and discharged in accordance with Division of Water Resources requirements at the time of its approval of the slurry wall. There is no new, additional water pumping associated with the proposed system. As noted in the revision request, an existing 88 -hp pump will be relocated to the west of its existing location and water will be discharged at a previously approved discharge point on the west boundary of the site to the South Platte River. Based upon the additional information provided to you today, verifying that the proposed technical revision does not result in any additional costs associated with reclamation, I Aggregate You in&ated that the Division will proceed with approving AI's revision request. West Central Region, Inc. 1687 Cole Boulevard, Suite 300 Golden, CO 80401 Telephone: 303 - 985 -1070 An Equal Opportunity Employer