2013-09-27_REVISION - C1982056 - Laserfiche WebLink

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Peab I ��1111 ENERGY Twentymile Coal, LLC 29515 Routt County Road 27 Oak Creek, CO 80467 970 879.3800 Mr. Jason Musick September 24, 2013 Colorado Division of Reclamation, Mining and Safety RECEIVED 1313 Sherman St., Room 215 Denver, Colorado 80203 303.866.3567 X8134 SEP 2 7 2013 Re: Minor Revision MR13 -267, EMD Water Monitoring Wells DIVISION OF RECLAMATION MINING AND SAFETY Dear Mr. Musick; With this submittal, Twentymile Coal, LLC (TC) is requesting CDRMS approval of a Minor Revision (MR13- 267) to our existing approved Mining and Reclamation Permit, for minor maintenance of existing ranch roads, construction of drill -pads, drilling and completion of two groundwater monitoring wells, and reclamation of the drill- sites. The purpose of the proposed water monitoring wells is to determine the level and extent of groundwater accumulations in the sealed Eastern Mining District (EMD) mine workings, and to provide for future monitoring of water level and quality in this area. The proposed activities would occur on lands and would affect minerals owned by the State of Colorado and controlled by TC (State Lease CO- 3229), as shown on Figure EX33A -F1, EMD Water Monitoring Wells, and would be conducted during 4°i quarter 2013. Environmental baseline studies were previously completed for the EMD and are included in the current PAP. Site- specific cultural resource surveys have been completed for the proposed drill sites and access, and will be documented by a cultural resource survey report, which will be forwarded on receipt. Drill -sites have been selected and located to facilitate access from existing County and ranch roads. Minor maintenance may be required for portions of the existing ranch roads, including grading to address rills or washouts and placement of suitable road -base materials, to assure good access during any wet conditions and minimize any road damage. Where direct access from existing roads is not feasible, drilling equipment and supplies will travel overland short distances during periods when ground conditions are favorable, to access the drill sites. Drill pads will be approximately 100 x 100 feet (0.23 acres), with soil material stripping limited to an area around the drillhole collar, and the area surrounding any mud pits necessary to support drilling operations, in order to minimize disturbance and facilitate site reclamation. Nominal 14 -inch -inch drillholes will be completed to a 60 -foot depth to set a surface casing, then the holes will be extended by drilling a nominal 10- inch drillhole to a depth of approximately 1,710 feet using a hammer drill with air for cuttings removal or conventional rotary drilling methods and drilling mud as the circulation medium. A 12 -inch or slightly larger surface casing will be set in the upper 60 -feet for each well, with 8 -5/8 -inch casing extending to a depth of 1,610 feet during drilling. A 4 -1/2 -inch casing will be extended from the surface to 1,610 feet, with 4 -1/2 -inch slotted screen extending from 1,610 to 1,710 feet. Once the 4 -1/2 -inch casing is in place, the 8 -5/8 -inch casing will be removed. A gravel pack will be placed in the screened interval, and all remaining casing will be fully grouted in the boreholes. On completion of the wells, they will be developed by cleaning and flushing the wells with fresh water. For each well, a pit approximately 12' x 12' x 10' will be excavated on the pad to contain the drilling mud and hold the drill cuttings. Drainage from the drill pads will be controlled using berms and straw wattles. For each well, the surface casing will extend above the ground surface and will be capped and locked to limit access. On completion of the drilling and well completion activities, any excess water will be pumped out of the cuttings pits into trucks and hauled off -site to a suitable disposal area, the cuttings pits will be allowed to dry out, pits will be covered and excavated material regraded over the pits, pads will be regraded to blend with the