Laserfiche WebLink
• Channel Designs <br />The surface water diversion dimensions were determined using 1\Iannings Equation Eor open channel <br />flow. All channels will be either gravel- or vegetated-lined channels. If flow velocities exceed 6 feet <br />per second, the channels will be lined with riprap or erosion will be controlled with the use of rock <br />check dams. Channels will be designed with a 0.3 Eoot freeboard. For channels where rock check <br />dams or straw bales are installed, a 1 foot freeboazd was added to the design depth. The Elk Creek <br />postmine channel will also be designed with a 1 foot freeboazd. Riptap sizes were determined using <br />Pader, OSM or limiting velocity methods. Given the uncertainty in determining riprap sizes for steep <br />grades, a factor of safety of 3 inches was added to the riprap Dso designed using the Pader method. <br />The limiting velocities were determined from the "Erosion and Sediment Pollution Control Program <br />1Vfanual", Bureau of Land and Water Conservation, Pennsylvania. The limiting velocities aze shown in <br />the channel design section. The Elk Creek channel was designed using the Simons/OSM method <br />which includes abuilt-in factor-of-safety. Riptap will consist of durable rock resistant to weathering <br />with a uniform gradation. <br />• This section contains design calculations for the following ditches: <br />Elk Creek Mine and D-Seam Portal Ditches <br />Yazd Ditches 1 and 2 <br />Berm Ditch <br />Refuse Ditches <br />Haul Road Ditch <br />Conveyor lA Ditch <br />East Clean Water Ditch <br />West Refuse Pile Diversion <br />West Refuse Ditch <br />East Refuse Ditch <br />Elk Creek Mine Ditches Dl, D2, D3 Upper, D3 Lower, D4, DS Upper, DS Middle, <br />DS Lower, D6, D7, D8 Upper & D8 Lower. <br />In addition, this section contains the design calculation for the following postmine temporary and <br />permanent ditches and channels: <br />• Substation 3 Channels <br />SS-1, SS-2, SS-3, & SS-4 <br />