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June 27, 2013 <br />Dr Berhan Keffelew <br />ivision of Reclamation Mining and Safety <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br />Re: Permit Number 42004-031 — Hazeltine Mine <br />;s �sVF <br />/Vpsgc�r /pN <br />i� <br />Technical Revision TR;92 — Adequacy Review Response <br />Dear Mr. Keffelew: <br />AGGREGATE <br />INDUSTRIES <br />This letter and the enclosed drawing are submitted in response to the Division's June 3, <br />2013 letters (2) regarding Aggregate Industries' (Al) April 30, 2013 revision request <br />which was submitted to address elevated surface water levels on the neighboring Orr <br />property. The letter responses follow the adequacy items as set forth in the Division's <br />review letter. <br />1) TR -02 supersedes the previously approved TR -01 plan. <br />2) The enclosed drawing provides the cross- section and additional features and <br />information as requested by the Division under this adequacy item. <br />3) The maximum flow capacity of the Agridrain is 3,500 cfs (under pressure). The <br />maximum flow rate that the Agridrain will need to handle in order to prevent a <br />rise in water level on the inlet side of the Agridrain is 1,750 cfs. <br />4) Select soils and clay collars will be installed around the inlet and outlet of the <br />Agridrain to ensure that this permanent drain is stable. <br />5) Flow diverted through the Agridrain into the excavated pit prior to bond release <br />will be directed into the existing pit dewatering system and discharged at a <br />previously approved discharge point to the South Platte River and therefore does <br />not cause injury to owners of water rights associated with the drained surface <br />flow, if any. Post bond release protection of any water rights related to surface <br />flow drainage into the reservoir will be addressed by the Division of Water <br />Resources as a condition of approval of the reservoir liner and any such <br />condition(s) will become an operational responsibility of the reservoir owner. <br />6) A rip -rap run down channel will be incorporated into the reservoir slope during <br />Aggregate Industires <br />West Central Region, Inc. <br />1687 Cole Boulevard, Suite 300 <br />Golden, CO 80401 <br />Telephone: 303 - 985 -1070 An Equal Opportunity Employer <br />