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III IIIIIIIIIIIII III <br />sss <br /> <br />~~ ~~ <br />12055 W. Second Place • P.O. Box 15596 • Lakewood, Colorado 80215 • Telephone (303) 989-5037 <br />R~rC~I~~~ <br />September 12, 1985 <br />SEP 2 01985 <br />Mr. Jeff Deckler <br />Reclamation Specialist <br />1313 Sherman Street <br />Denver, Colorado 80203 <br />MINED LAND <br />RECLAMATION DIVISION <br />RE: Technical Revision to Modify Ponds 006 and 007. Response to Adequacy Issues. <br />Dear Mr. Deckler: <br />Following are responses to adequacy issues one (1) through eight (8) as outlined in <br />Candy Thompson's memorandum of June 14, 1985. <br />Adequacy Issue (1) <br />The subdrainage areas identified in Table 1 of our May 29, 1985 submittal were <br />taken from page 21, Volume 2 of the New Elk Permit Application. <br />• <br />The only modification to the ditch system involves extending the existing ditch <br />(Ditch 8-3, Map 13C, Volume 4) past 006 and into 007. The ditch enters 007 at CMP <br />No. 13. <br />Adequacy Issue (2) <br />Peak flows were taken directly from the New Elk Mine runoff calculations (Volume <br />II, Exhibit 16). Peak flows for 006 subdrainages = 20.00 cfs; peak flows for 007 <br />subdrainages = 4636 cfs. <br />Adequacy Issue (3) <br />Emergency Spillway 007 <br />Given: <br />(1) 25 year 24 hour event = 3.5 inches <br />(2) Drainage area = 54.0 acres <br />(3) CN = 85 (average for all subdrainages) <br />(4) Moderate slope (3-7%) <br />(5) Peak discharge = 46 cfs/inch of runoff <br />(f) Runoff = 2.03 with CN = 85 <br />Peak discharge = 46 cfs/inch x 2.03 inches = 93.4 cfs <br />• <br />