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Every five years, SPL will monitor the sediment storage capacity of sediment ponds 006, 015, 016, and 017 <br />with one or a combination of the following methods, as applicable: <br />1.) Reference Stake - A reference stake will be set at a predetermined clean-out elevation beneath <br />the principal spillway. When sediment storage reaches this elevation, corrective action will be <br />implemented to restore adequate sediment storage. Reference staking will be utilized in ponds <br />that are normally dry and as an indicator for monitoring personnel as to when a more detailed <br />survey of sediment storage capacity is warranted. <br />2.) Cross Sectioning or Grid Method -For the ponds that normally contain wafer year round, or <br />where a reference stake cannot be detected below the water surface, a survey cross section or <br />grid method will be used to determine sediment volume using accepted engineering practices. <br />The survey would be performed when needed to determine sediment storage capacity and to <br />determine when corrective action is required to restore adequate pond capacity. <br />3.► Aerial Mapping - An alternative method is photogrammetric mapping that would create an <br />accurate 1" = 50' topographic map with 2 ft. contour intervals to determine the remaining storage <br />volume beneath the principal spillway. This method could be used as the sole method for dry ponds or <br />used in conjunction with the surveyed cross section method for ponds partially full of water. Once the <br />topographic map has been generated, accepted engineering methods will be utilized to perform the <br />volumetric calculations. <br />Corrective action required to restore adequate sediment storage capacity may include the following: <br />1.) Raise the spillways and redesign the pond in order to restore adequate storage capacity and to <br />comply with the applicable regulations. <br />MR -83 4b Revised 10/16 <br />