Laserfiche WebLink
SPILLWAY CAPACITIES <br />i The stock ponds were analyzed to determine if the spillways for the permanent stock ponds have the <br />capacity to pass the peak dischazge from the 25-yeaz, 24-hour storm event In addition riprap <br />requirements were also evaluated. <br />The peak dischazge, spillway capacity and riprap requirements were determined using SEDCAD 4. <br />The peak discharge was determined using the same methodology and assumptions outlined in this <br />permit A curve number of 71 was used for this evaluation which represents a hydrologic soil group B <br />with a fair herbaceous cover. All hydrology inputs and results are shown on the attached SEDCAD 4 <br />computer printouts. <br />To determine spillway capacity, capacity tables were developed based on the existing spillway bottom <br />widths using SEDCAD 4. The SEDCAD 4 results are attached. Using these tables and the peak flow <br />from the 25-yeaz, 24-hour storm event, the depth of flow and freeboard was determined for each stock <br />pond. The results are show on the table below. <br />Riprap requirements were determined using the OSM method found in SEDCAD 4. All inputs and <br />results are shown on the attached SEDCAD 4 printouts. The results are summarized on the following <br />table. <br />SENECA II <br />STOCK POND <br />SPILLWAY SUMMARY <br />u <br />Pond 25 Year <br />Flow <br />(cfs) Bottom <br />Width <br />(h) Invert <br />Spillway <br />(h) Depth of <br />Flow <br />(fr) Peak <br />Flow Elev. <br />(fr) Top of <br />Embankment <br />(fr) Freeboard <br /> <br />- (h) Riprap <br />d50 <br />(in) <br />T4 17.4 6 7096.0 1.1 7097.1 7102.1 5.0 12 <br />T8 13.5 8 7318.5 0.7 7319.2 7321.6 2.4 6 <br />T16 G.0 10 7464.6 0.5 7465.1 7469.0 3.9 6 <br />T17 12.5 20 7135.0 0.4 7135.4 7138.0 2.6 9 <br />T20 6.4 20 7202.0 0.4 7202.3 7204.3 2.0 6 <br />T26 32.19 18 7333.3 0.9 7334.2 7336.4 2.2 9 <br />T28 24.44 20 7502.6 0.8 7503.4 7505.0 1.G 9 <br />T29 30.9 18 7403.8 0.9 7404.7 7406.0 1.3 12 <br />T30 19.04 18 7674.0 0.7 7674.7 7675.8 1.1 9 <br />T31 8.89 15 78]8.0 0.8 7818.8 7820.3 1.5 6 <br />T32 7.31 12 7812.6 0.5 7813.0 7814.8 1.8 6 <br />T33 10.33 17 7212.0 0.8 7212.5 7213.8 1.3 9 <br />L~ <br />