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NEWMONT; <br /> ���� Newmont Mining Corporation <br /> DEC26363 South Fiddler's Green Circle Suite 800 <br /> Greenwood Village CO 8011 1 <br /> T 719-689-2977 <br /> �SION OF RECLAMATION F 719-689-3254 <br /> MINING&SAFETY www newmont com <br /> SENT CERTIFIED, RETURN RECEIPT REQUESTED <br /> 7015-1660-0000-0779-8256 <br /> 19 December 2016 <br /> Mr. Timothy Cazier, P.E. <br /> Environmental Protection Specialist <br /> Colorado Department of Natural Resources <br /> Division of Reclamation, Mining and Safety <br /> Office of Mined Land Reclamation <br /> 1313 Sherman Street, Room 215 <br /> Denver, Colorado 80203 <br /> Re: Permit No. M-1980-244: Cripple Creek & Victor Gold Mining Company ("CC&V"); Cresson <br /> Project; — Globe Hill Stormwater Diversion Channel —TR#86 Preliminary Adequacy Review <br /> Response <br /> Dear Mr. Cazier: <br /> On November 28, 2016 the Cripple Creek and Victor Gold Mining Company (CC&V) submitted <br /> Technical Revision (TR) #86 proposing the installation of a stormwater diversion channel <br /> around the future development of the Globe Hill Pit at the Cresson Project Permit M-1980-244. <br /> On December 1, 2016 CC&V received Preliminary Adequacy Review comments from the <br /> Division of Reclamation, Mining and Safety (DRMS). Please find the comments from DRMS <br /> below in italics and CC&V's responses in bold. <br /> Comment 1). Hydrologic Analysis. The second paragraph under "Stormwater Design" on the <br /> second page of the TR request states "the total watershed contribution is 74 acres", and that a <br /> conservative "0% infiltration" approach was used to estimate a 100-year, 24-hour peak flow <br /> runoff of 11 cfs. The Division performed a rough check of the peak flow and the contributing <br /> area. The peak flow was check using the SCS (now NRCS) March 1984 "Procedures for <br /> Determining Peak Flows in Colorado"Figure S-1A (see Attachment A). Assuming a SCS curve <br /> number(CN) of 90, low infiltration, but not zero, the peak flow was estimated to be 218 cfs. An <br /> additional peak flow estimate was done using a more moderate CN of 70, which resulted in a <br /> peak flow estimate of 66 cfs. The Division estimated the contributing watershed area using <br /> Google Earth Pro with a USGS map overlay (see Attachment 8). This showed a contributing <br /> area of approximately 128 acres. <br /> a. Please double check your runoff analysis and provide the Division with calculations <br /> demonstrating the 11 cfs (or revised) peak flow estimate. Please be aware that the <br /> diversion channel needs to be designed for the worst case runoff condition, which is <br /> likely when all the contributing area south of the diversion channel has been cleared and <br /> grubbed, and the North Cresson/Globe Hill pit has not progressed to the point of <br /> capturing any of the contributing area. Also, if CC&V elects to estimate the peak flow <br />