Laserfiche WebLink
COLORADO <br />Division of Reclamation, <br />Mining and Safety <br />Department of Natural Resources <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br />April 14, 2016 <br />Interoffice Memo <br />King Coal Mine (Permit No. C-1981-035) <br />Technical Revision No. 20 (TR -20) <br />Robin, <br />I have reviewed the latest submission of King Coal Mine's (KC) TR -20 and associated changes in <br />regards to the design of the West Waste Bank (WWB), Trautner's "Revised Geotechnical <br />Engineering Study for the National King Coal I West Waste Bank Coal Mine Waste Disposal Area" <br />(Report) as well as additional applicable sections of KC's PAP and have the following comments: <br />4.05 - Hydrologic Balance <br />As discussed, KC has not submitted a hydrologic demonstration or design criteria to ensure the <br />newly proposed reaches, previously constructed reaches and associated culverts are sufficiently <br />designed to handle flows as required by Rule 4.05.3(3). Additionally, currently approved KI <br />Appendix 11 — Hydrologic Designs no longer remains applicable or accurate due to the proposed <br />routing of reaches as proposed under TR -20. Most notable differences are the addition of Reach 7- <br />B, length reduction of Reach 7, Reach 10 now routes to Reach 7-B rather than Reach 7, and the <br />increase in length of Reach 6 including additional surficial runoff directed to it from the West Waste <br />Bank. Please have KC update KI Appendix 11 — Hydrologic Designs to include changes as <br />proposed under TR -20. <br />4.10 — Coal Mine Waste Banks <br />Please have KC submit design detail regarding the proposed Bench Under Drain associated with the <br />West Waste Bank to ensure compliance with 4.10 and more specifically 4.09.2(2). Additionally, it <br />appears from the proposed Map King I-016 — West Waste Bank Design that the west end of the <br />Bench Under -Drain potentially drains into the main substation pad. Please have KC add additional <br />detail in regards to the discharge points of the Bench Under -Drain or clarification to where the <br />underdrain directs groundwater to. <br />1313 Sherman Street, Room 215, Denver, CO 80203 P 303.866.3567 F 303.832.8106 http://mining. state. co. us <br />John W. Hickenlooper, Governor I Mike King, Executive Director I Virginia Brannon, Director <br />