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<br />2.05.3(4)Ia)(ii) <br />The existing sedimentation pond was certified by Larry M. <br />Reschke, P.E. on May 7, 1985. The capacities of the pond as cer- <br />tified and the required pond size after reclamation, in accord- <br />ance with Table 2.05.3(4)(d1-5, are as follows: <br />Certified Required for <br />5/7/85 Poat <br />Reclamation <br />Water storage capacity 2.37 A.F. 2.29 A.F. <br />Sediment capacity 1.22 A.F. 0.78 A.F. <br />Total capacity 3.59 A.F. 3.08 A.F. <br />The required sediment pond capacity as well as the peak flow cal- <br />culations were performed in accordance with the manual titled <br />Procedures for Determining Peak Flows In Colorado dated March <br />1984. The sediment capacity was determined using the Universal <br />Soil-Loss Equation. These calculations are shown in detail on <br />Tables 2.05.3(4)(d)-4 & 5. <br />The size of the main drainage channel was not changed. The main <br />• drainage channel, also referred to as the major drainage channel, <br />is discussed on page 128a. <br />The upper diversion ditch and the lower catch ditch were sized <br />using Manning's equation, Q = A 1.486/n R~i3 Sl~a. A trapezoidal <br />channel was chosen with a 12-inch wide bottom. With a 9-inch <br />flow depth, a 2% slope and a coefficient of roughness, n, of <br />0.04, the channel is capable of passing 3.9 c.f.s. The flow cal- <br />culations for the upper diversion and the lower catch ditch show <br />a peak flow of 2.59 and 2.69 c.f.s. respectively. <br />The 24-inch diameter culvert was sized using nomographs contained <br />in the Handbook Of Steel Drainage & Highway Construction <br />Products. The flow calculations for the culvert show a peak flow <br />of 9.52 c.f.s. A headwater controlled 24-inch diameter culvert <br />is capable of passing 11.5 c.f.s. <br />The drainage channel leading up to and away from the 24-inch <br />diameter culvert must pass the 9.52 c.f.s. flow. The same <br />trapezoidal channel was chosen for this ditch. A 14-inch flow <br />depth and a 2 1/2 % elope are required to pass the design flow. <br />Where the drainage channel on the west side of the culvert inter- <br />sects with the west aide terrace ditch, the size of the channel <br />will be increased as shown on the post reclamation drainage sys- <br />tem map, Drawing No. 2.05.3(4)-2a <br /> <br />-99- Revised July 11, 1988 <br />