Laserfiche WebLink
1. Reference Stake - A reference stake will 6e set at a predetermined clean-out elevation <br />beneath the principal spillway. When sediment storage reaches this elevation, corrective <br />action would be implemented to restore adequate sediment storage. Reference staking will <br />be utilized in ponds that are normally dry and as an indicator for monitoring personnel as to <br />when a more 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 <br />section or grid method will be used to determine sediment volume using accepted <br />engineering practices. The survey would be performe.. when needed to determine <br />sediment storage capacity and to determine when corrective action is required to restore <br />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 <br />method for dry ponds or used in conjunction with the surveyed cross section method for <br />ponds partially full of water. Once the topographic map has been generated, accepted <br />engineering methods 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 <br />and 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. <br />The material that is not suitable for topsoil will be graded into the surrounding topography within the <br />disturbance 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 <br />mining permit, the NPDES permit, and Section 4.05.61311b1. All sedimentation ponds will 6e inspected <br />quarterly under the supervision of a registered professional engineer and reported to the CDMG. <br /> <br />5 <br />