2016-09-26_REVISION - M2004031 (4)

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AVCOLORADO Division of Reclamation, Mining and Safety Department of Natural Resources 1313 Sherman Street, Room 2?5 Denver, CO 80203 Date: September 26, 2016 RE: Rationale for Recommendation to Approve Amendment No. 01 (AM -01) with Objections, Aggregate Industries, Hazeltine Pit, Permit No. M-2004-031 Introduction Herein, all references to the Act and Rules refer to the Colorado Land Reclamation Act for the Extraction of Construction Materials, 34-32.5-I01 et seq., C.R.S. (Act), and to the Mineral Rules and Regulations of the Colorado Mined Land Reclamation Board for the Extraction of Construction Materials (Rules or Rule). A copy of the Act and Rules are available through the Division's web site at www.mining.state.co.us. On September 26, 2016, the Division of Reclamation, Mining and Safety (Division or Office) issued its recommendation to approve AM -0I for the Hazeltine Pit over public objections. This document is intended to explain the process by which the Division arrived at its recommendation to approve, over public objections, and respond to the issues raised by the objecting parties and commenting agencies. The Division reserves the right to further supplement, amend, modify, or clarify this document and recommendation with additional details as necessary. Summary of the Review Process Aggregate Industries (Operator) filed the application for AM -01 with the Division on December 16, 2015. The amendment was submitted, not to increase affected area or change the post - mining land use (developed water storage), but to comply with an October 28, 2015, Board Order to provide a permanent groundwater mounding mitigation plan for Division review. To address groundwater mounding, the amendment obligates the Operator to install a groundwater drain structure, referred to the Orr drain. The Orr drain is intended to reduce the groundwater levels up -gradient of the existing slurry wall and adjacent to the Orr property to approximate pre -slurry wall groundwater levels (drain invert will be set at an elevation of 5036.5 feet). The drain will allow groundwater to gravity discharge into the lined reservoir. The groundwater will discharge from the reservoir through a new discharge pipe, to be constructed at the designed normal high water elevation of the reservoir (5036 feet), back into the South Platte River. The Operator believes installation of these structures will restore groundwater in the vicinity of the Orr property to approximate pre -slurry wall elevations and that disturbances to the hydrologic balance will thereby be minimized. 1313 Sherman Street, Room 215, Denver, CO 80203 P 303.866.3567 F 303.832.8106 http://mining.state.co.us John W. Hickentooper, Governor i Bob Randall, Executive Director I Virginia Brannon, Director or.. Cocos� 8.7