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SAE #2. It was reclaimed along with the BB detour road and no longer exists as of April 2010. <br />The sedimentation ponds are designed, constructed, and maintained as follows: <br />a. Ponds 008, 009, 012, and 013 have been designed to contain the 25 year, 24 hour <br />event with no discharge from the emergency spillway. Ponds 015, 016, and 018 <br />have been designed for a 100 -year, 24-hour event with no discharge. <br />b. The sedimentation ponds are designed to provide adequate sediment storage <br />volume in compliance with the DRMS regulations. The actual designs are based <br />on a minimum 3 year sediment volume based on USLE calculations. Actual <br />construction may cut more volume below the dam level (incised storage) to lessen <br />expensive cleanout during the operation. <br />c. The principal spillway design is an 18-24" diameter CMP or other pipe which will <br />have a valve on the entrance. This pipe will be stopped down in the inlet side to a <br />6" valve which will be controlled by a wheel on the pond embankment. During <br />normal conditions, the valve will be left slightly open to provide 24 hour <br />detention time for each pond during the large events. This is accounted for as <br />weep holes in the SEDCAD design runs. When a large event occurs, the operator <br />will wait until the Imhoff cone test shows that the water meets effluent standards <br />prior to discharge. If an Imhoff cone shows that the water meets the effluent <br />standard of 0.5ml settleable solids per liter, the valve will be opened until the <br />water has dissipated to the valve level. It will then be left slightly open to allow <br />detention time for subsequent storms. For Ponds 008, 012 and 013, SEDCAD <br />analysis has shown that the effluent from a slightly open valve still meets effluent <br />requirements. For these ponds, the operator can decide to leave the valve cracked <br />or shut as described above. <br />d. Appropriate combinations of principal and emergency spillways to safely contain <br />or discharge the runoff from a 25 -year, 24-hour precipitation or larger event, as <br />required by the DRMS's regulations, will be installed. If a pond is designed to <br />contain the runoff from a 25 -year, 24-hour event, an emergency spillway cut into <br />the dam will still be installed. <br />e. Pond freeboard will be a minimum of 1.0 feet from the highest level of water <br />allowed in the pond (or emergency spillway) to the top of dam. <br />f. The top of dam width will beat least 10.0 feet in all areas. <br />Section 2.05.3(3) Page 13 February 2017 (TR -78) <br />