2014-08-11_REVISION - C1982056 (2)

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��1111 Peabodq Twentymile Coal, LLC Mr. Dan Hernandez Colorado Division of Reclamation, Mining and Safety 1313 Sherman St., Room 215 Denver, Colorado 80203 303.866.3567 X8134 Re: Minor Revision MR14 -280, Monitoring Well Relocation Dear Mr. Hernandez; 29515 Routt County Road 27 Oak Creek, CO 80467 970.879.3800 August 6, 2014 RECEIVED AUG 112014 cr'Wlsrmm *f lRealwatiPo, fmia" A:we�y With this submittal, Twentymile Coal, LLC (TC) is requesting CDRMS approval of a Minor Revision (MR14 -280) to our existing approved Mining and Reclamation Permit, to relocate the proposed downgradient groundwater monitoring well for the Wolf Creek Reserve (WCR) area. TC's original intent was to pull the casing for Drillhole WC013, ream the drillhole to a larger diameter, install surface and well casing consistent with the approved monitoring well completion diagram, and complete and develop the well as the downgradient monitoring well for development of the Wolf Creek Reserve. Drillhole WC013 is located on the existing 6MN facilities pad and is within the existing facilities disturbance area. TC's drilling contractor was not successful in their attempt to break the existing casing loose and pull the casing. Consequently, TC had the contractor plug and seal Drollhole WC013, consistent with the drillhole reclamation plan and applicable State Engineer requirements. In order to establish the required downgradient monitoring well, TC proposes to offset from Drillhole WC013 approximately 150 feet, and drill and complete the well (WC013A) consistent with the previously approved plans. The proposed new location is still on the 6MN facilities pad and within the existing facilities disturbance area. The proposed activities will occur on lands, and will affect surface and minerals owned or controlled by TC, and will be conducted during fall 2014, as shown on Figure EX52 -F4, WCR Supplemental Coreholes II. As an existing disturbance area, no additional soil removal, grading, or other surface preparation is necessary. Wattles, sediment fence, and/or berms will be used to control site drainage and prevent off -site sediment transport in the immediate drilling area, with overall drainage control for this area provided by the existing 6MN Sedimentation Pond. A nominal 9.625 -inch drillhole will be completed using conventional rotary drilling methods and drilling mud as the circulation medium, to a depth of approximately 1,550 feet. On completion of drilling, the drillhole will be cased, completed, and developed as a groundwater monitoring well. This submittal includes revised PAP text and supporting materials, as identified by the accompanying Summary of Revisions /Additions. In order to complete drilling before weather conditions become too adverse, TC would like to initiate the proposed activities as soon as possible, and therefore, requests the assistance and cooperation of the CDRMS is completing review and approval of this application in a timely manner. Once you have opportunity to review this submittal, please feel free to contact me with any questions, or to discuss the submittal and related matters. We appreciate your attention and assistance.