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6,734.69 0.523 1.492 <br />6,735.60 0.562 1.986 <br />6,735.68 0.566 2.031 <br />6,735.69 0.566 2.036 <br />The peak stage for the 100-yeaz, 24-hour event accounts for the following volumes: <br />0.02 ac-ft of sediment storage (maximum that will occw over three yeazs). This <br />occurs at an elevation of 6,730.74 ft amsl. Therefore, the SEDCAD mode] redefines <br />the Elevation-Capacity-Dischazge Table to show 0.000 ac-fr capacity at the top of the <br />sediment storage elevation, i.e.: <br />The input table above shows a capacity of 0.020 ac-ft at an elevation of 6,730.74 <br />feet. <br />The mode] output table shows a capacity of 0.000 ac-ft at an elevation of 6,730.74 <br />feet. <br />At the redefined starting elevation of 6,730.74 feet and capacity of 0.000 ac-ft, the <br />model adds the following volumes: <br />0.007 ac-$ (shown rounded as O.OI ac-ft in the model output) of initial pool <br />volume on top of the sediment storage <br />1.419 ac-ft of runoff volume from the l 00-yeaz, 24-how event <br />1.426 ac-fr of volume required above the sediment storage elevation. At this <br />elevation, the pond still has 1.01 feet of freeboard before overtopping. <br />The runoff volume resulting from the 25-year, 24-how event is 1.023 ac-ft. By <br />subtracting this number from the 100-year, 24-hour volume (plus the initial pool volume) <br />of 1.426 ac-ft, we have determined that the pond must not contain more than 0.403 ac-ft <br />to maintain the capacity to still contain runoff from the 25-year, 24-how event with at <br />least 1.0 feet of freeboard. The elevation cornesponding to the capacity of 0.403 ac-ft is <br />6,732.33 feet. At an elevation of 6,733.60 feet and pond capacity of 0.947 ac-ft, the pond <br />could completely contain the addition of the 25-year, 24-hour event with no freeboard. <br />Following is a summary of the above information: <br />100-yeaz, 24-hour rainfall runoff volume = 1.419 ac-ft <br />25-year, 24-how rainfall runoff volume = 1.023 ac-ft <br />3-yeaz sediment storage volume = 0.02 ac-ft <br />]nitial pool volume = 0.007 ac-ft (shown in model out as rounded value of 0.01 ac-ft) <br />Elevation <br />feet <br />6,730.52 <br />6,730.74 <br />6,732.33 <br />6,733.60 <br />6,734.59 <br />6,735.60 <br />Comments <br />bottom of the pond without sediment deposition <br />bottom of the pond with 3 yeazs sediment deposition (0.02 ac-ft) <br />pond has capacity to contain 25-year, 24-how event with ].O] ft freeboard <br />pond has capacity to contain 25-year, 24-how event with no freeboard <br />peak stage of ] 00-yeaz, 24-hour runoff volume with ] .Ol ft freeboard <br />maximum containment of pond (1.97 ac-fr) before overtopping <br />