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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 would <br />be implemented to restore adequate sediment storage. Reference staking will be utilized in <br />ponds that are normally dry and as an indicator for monitoring personnel as to when a more <br />detailed survey of sediment storage capacity is warranted. <br />2. Cross Sectioning or Grid Method -For the ponds that normally contain water year round, or <br />where a reference stake could not be detected below the water surface, a survey cross section <br />or grid method will be used to determine sediment volume using accepted engineering <br />practices. The survey would be performed when needed to determine sediment storage <br />capacity and to 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 <br />storage volume beneath the principal spillway. This method could be used as the sole method <br />for dry ponds or used in conjunction with the surveyed cross section method for ponds partially <br />full of water. Once the topographic map has been generated, accepted engineering methods <br />will be utilized to perform the 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 <br />to comply with the applicable regulations. <br />2. Excavate the ponding area and enlarge the sediment storage capacity. <br />The material excavated will be tested to determine its suitability as topsoil and utilized in reclamation. The <br />material that is not suitable for topsoil will be graded into the surrounding topography within the disturbance <br />area, topsoiled, and revegetated in accordance with the approved reclamation plan. <br />Site specific conditions will determine the construction methods and equipment utilized at the time of <br />excavation. Sediment removal and water discharges will be conducted consistent with the approved mining <br />permit, the NPDES permit, and Section 4.05.6(3)(b). All sedimentation ponds will be inspected quarterly <br />under the supervision of a registered professional engineer and reported to the CDMG. <br />• <br />5 <br />