Laserfiche WebLink
i <br />i <br />i <br />6.0 Watershed Sediment Yield <br />The maximum sediment allowed in the sediment pond would be 2.62 acre-feet at an <br />elevation of 7231.9 feet. The sediment will have to be removed when it reaches 60 <br />percent of this amount or 1.57 acre-feet at an elevation of 7229.25 feet. <br />Using the sediment numbers from 10yr-24hr event, 164.4 tons of sediment would be <br />deposited in the pond. Assuming an average density of 110 Ibs/ft3 it would take <br />approximately 25 storms to fill the pond to the level of 7229.25 feet. Refer to Appendix <br />1, Sediment Pond "As Built". <br />6.0 Evaluation <br />Basin A <br />All the ditches will be adequate to handle all the runoff as calculated. Refer to Appendix <br />2, Runoff Control Structures Verification for Basin A. <br />The culverts will be adequate to handle the runoff as calculated. The entrance to <br />Manhole # 3 will have sufficient depth to create the required head that will push the <br />water through the 24-inch culvert. Refer to Appendix 2, Runoff Control Structure <br />Verification for Basin A and Table 1, Culvert Comparison. <br />Basin B <br />All the ditches will be adequate to handle all the runoff as calculated. Refer to <br />Appendix 3, Runoff Control Structures Verification for Basin B. <br />The culverts will be adequate to handle the runoff as calculated. The entrance to the <br />culvert next to the coal stockpile (32.2LF x 24 in. Dia. CMP) will require a head of .72 <br />feet to push water through the culvert. According to the map there is sufficient elevation <br />to create the required head. The culvert (90LF x 24 in. Dia. CMP) that goes under the <br />road at the truck loadout will require a head of 1.10 feet to push water through the <br />culvert. According to the map this inlet is a catch basin and there is sufficient elevation <br />to create the required head. The culvert (82LF X 24 in. Dia. CMP) at the base of the <br />coal stockpile will require a head of 0.80 feet to push water through the culvert. <br />According to the map this inlet is a catch basin and there is sufficient elevation to create <br />the required head. Refer to Appendix 3, Runoff Control Structures Verification for Basin <br />B and Table 1, Culvert Comparison.