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. <br />Wyoming <br />full Compon~ iii iiiiiiiiiiiii iii <br />• 12055 W. Second Place • P.O. Box 15596 • Lakewood, Colorado 80215 • Telephone (303) 989-5037 <br />May 1, 1985 <br />~~~~~ <br />Mr. Jeff Deckler ~ "~ <br />Colorado Mined Land Reclamation Divison ' <br />1313 Sherman Street ~ `',. <br />Denver, Colorado 80203 ~•~ . ._,., <br />Re: Response to New Elk Permit Revision Stipulations 4, 7, and 8, and Stipulation 2, <br />Technical Revision to the Permit Revision. <br />Dear A4r. Deckler: <br />The enclosed as-built drawing, as-built hydraulic calculations, and certification are <br />for the Purgatoire River channel diversion at the New Elk Mine. A post construction <br />survey showed that the channel bottom was narrower than designed and the south <br />embankment slope was 2.84H:1V not 2H:1V. <br />• These variances were taken into account and a hydraulic analysis was done to see if <br />the 100 yr-24 hr event (7910 cfs) could be handled by the channel. The rip-rap on the <br />south embankment slope from station 0+30 to 1+90 was extended vertically to adjust for <br />the higher flowline. The remaining rip-rap height on both side slopes was sufficient. <br />Rip-rap size was also increased due to the greater tractive forces on the side slopes. <br />The new D90 rip-rap size on the 200' radius curves is 2.4 feet while the straight section <br />D50 size is 1.5 feet. <br />If you have any questions or need additional information, please call. <br />Sincerely, <br />ST~.~ ~~ E <br />Steve Magnuson P.E. <br />Mining Engineer <br />Enclosure <br />SDM/cs <br />cc: Anita Culp <br />Jack Snow <br />Dave Stout <br />• Mike Kolin <br />