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• Although the primary means of sediment control are diversion structures <br />and a sedimentation pond, Sunbelt will utilize, as necessary, straw <br />dikes, riprap, check dams, mulches, vegetative sediment filters, dugout <br />ponds, or other measures that reduce overland flow velocity or runoff <br />volume. <br />4.05.6 Sedimentation Ponds <br />The location of the planned sedimentation pond is presented on the <br />Drainage and Sediment Control Plan Map (Map 6). The design plans and <br />specifications for the sedimentation pond are presented in Section <br />2.05.6. The sedimentation pond will be located as close as practical to <br />the area being disturbed by surface facilities. <br />This application contains calculations used to determine runoff volumes <br />• and flow rates for the 10-year, 24-hour precipitation event and <br />subsequent sediment volumes. The precipitation data were obtained from <br />• the NOA Atlas 2, Volume 3, for Colorado; soil types were obtained from <br />the Soils Map (Map 4). The design of the sedimentation pond is based on <br />worst case conditions. The worst case condition exists during and just <br />after an area has been disturbed and before any final revegetation of <br />the construction site is completed. <br />A non-clogging, dewatering device will be located at a lower elevation <br />on a maximum sediment storage volume. Dewatering will be achieved as <br />necessary to apply with the applicable state laws and regulations. <br />Sediment will be removed from the sedimentation pond when the volume of <br />sediment accumulates to not greater than 60 percent of the designed <br />sediment storage volume. Yearly measurements of sediment accumulations <br />will be conducted. The pond will be cleaned out when water levels are <br />lowest, and the least amount of precipitation is expected. The removed <br />sediment may be used as topsoil or subsoil if it meets the suitability <br />criteria discussed under Section 2.04.9. <br />• <br />4.05-5 <br />