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Ditch D -D2 <br />Ditch D -D2 is formed when the flow from ditch D -D1 and ditch D -E1 join below <br />sediment pond C. From the intersection of the two flows the ditch becomes a V -Ditch <br />that must be capable of handling the combined flow from the two ditches (1.79 + 14.62) <br />= 16.41 <br />The following information is generated from the use of the computer program Haestad <br />Methods FlowMaster I version 3.43. The ditch side slopes are 1.5h:ly, Manning's n = <br />.03. <br />Ditch <br />Flow <br />Velocity <br />Flow cfs Grade <br />Depth <br />fps <br />16.41 2% <br />1.5 <br />5.1 <br />16.41 10% <br />1.1 <br />9.3 <br />Construct Ditch D -2 two feet deep to allow for freeboard. The section with the 10% <br />grade will require gunnite riprap or riprap and concrete lining for erosion protection. <br />Culvert C -D1 <br />Culvert C -D1 is located in ditch D -D2. The culvert must be 30" in diameter to handle <br />the 16.41 cfs flow. Ditch D -02 must be constructed at least 30" deep at the transition <br />between the ditch and culvert <br />I* Drainage Area E <br />Drainage area E is the upland area located above the haul road that provides access to <br />the gob pile. A berm will be constructed along the south side of the road to contain <br />run -off to the site. A single ditch will be constructed on the north side of the road to <br />handle the flow from drainage area E. The peak flow for this area is 1.79 cfs. <br />Ditch D -E1 <br />Drainage area E is the upland area located above the haul road that provides access to <br />the gob pile. A berm will be constructed along the south side of the road to contain <br />run -off to the site. A single ditch will be constructed on the north side of the road to <br />Ditch Flow Velocity <br />Flow cfs Grade Depth fps <br />1.79 2% 0.65 2.90 <br />Construct ditch D -E1 1.5 feet deep to allow for freeboard. Alternative sediment control <br />features will be installed in the ditch to trap sediment before it leaves the site. <br />Culvert C -E1 <br />Culvert C -E1 was deleted from the design Jan. 1998. <br />PR -07 EXH -8 -12 2/03 <br />