2019-07-03_REVISION - C1981010 - Laserfiche WebLink

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Grouse to E. Pyeatt Diversion Ditch The Grouse to E. Pyeatt Diversion Ditch will be constructed in 2019 to temporarily divert approximately 70 acres westward from the Grouse drainage into the East Pyeatt drainage system, This is needed to allow topsoil stripping in the adjacent drainage basin. The 10 gear/2 4 hour storm event was used to size the diversion ditch. This storm produces 1,40 inches. While the majority of the remaining stripping area is assumed to be disturbed at once, it is probable that only portions of the topsoil stripping area may be contributory in a given time. The trapezoidal ditch will be about 3600 feet in length, 15 feet in width with 2H,1V side-slopes and a typical channel slope of 2.78 percent (0.0278 ft/ft). The peak flow resulting from the design storm produces approximately 33.4 cfs. Under these design conditions, the channel will flow about 0.49 feet in depth at a velocity of about 4.2 feet/sec. In order to assure freeboard, the minimum ditch depth will be 2.5 feet to allow adequate freeboard. Near the lower portion of the diversion ditch near Station 0+00, the ditch depth approaches about 25 feet. The following materials accompany this submittal-, • Figure 1, "Grouse Diversion to East Pyeatt Ditch" S E DCAD ,model, 10 year-2 4 hour event for this ditch ENGINEERING CERTIFICATION I am a Registered Professional Engineer in the State of Colorado and a representative of Environmental Solutions, Inc, P. 0. Box 2996, Cheyenne, Wyoming, Being familiar with the Trapper Mine operation and the coal program permitting process in Colorado, to the best of my knowledge and experience the attached document meets the requirements of current regulations and the applicable requirements of the approved permit document within CDR MS Permit C-1981-010. 41*0 POO go Pe cS 3225 AL lilt 0 THOMAS C PETEA�5R___ P.E. No.32257 TR-1 23, June, 2019