Laserfiche WebLink
• Energy Dissipaters <br />Energy dissipaters will be constructed at the location <br />of reclaimed ponds P-7, P-6 & P-5. The dissipaters <br />will be rock check dams. The check dams will be 10' feet <br />wide and 1.1-feet deep. The triangular channels will be <br />constructed to provide a smooth transition between the V-type <br />collection ditch and the rock check dams. In order to verify <br />the capacity of the check dams it will be assumed that the dams <br />are plugged off and act as sharp crested weirs. The following <br />calculation will determine the flow depth over a ten foot <br />wide sharp crested weir. <br />The flow across a sharp <br />following formula. Ref <br />Urquhart, Fourth Editio <br />K = WEIR FACTOR <br />L = EFFECTIVE LENGTH OF <br />H = MEASTURED HEAD <br />Q = <br />crested weir is calculated using <br />Civil Engineering Handbook, <br />page 4-49. <br />3.400 <br />WEIR 10.000 FEET <br />0.500 FEET <br />12.02 CFS <br />Q REQUIRED 9.82 CFS <br />The rock check dams will be constructed in a location at <br />• which the total depth of the channel can be 1.9 feet. <br />The required 1.9-foot depth will provide for the 1.1 foot <br />high check dam, the 0.5 feet depth calculated for the <br />sharp crested weir and 0.3 feet freeboard. (1.1' + 0.5' +0.3') <br />It is possible that erosion maX occur upgradient of the check <br />dams. The ditches will be monitored for erosion. If necessary <br />the ditch erosion protection will be enhanced. <br />• <br />4-B:11 <br />November 1994 <br />