Laserfiche WebLink
capacity is no longer available, sediment removal or other corrective actions will be <br /> taken to restore adequate sediment storage capacity to the pond. <br /> Peabody will monitor the sediment storage capacity of each pond with one or a combination <br /> of the following methods, as applicable: <br /> 1. Reference Stake - A reference stake will be set at a predetermined clean-out <br /> elevation beneath the principal spillway. When sediment storage reaches this <br /> elevation, corrective action would be implemented to restore adequate sediment <br /> storage. Reference staking will be utilized in ponds that are normally dry and <br /> as an indicator for monitoring personnel as to when a more detailed survey of <br /> sediment storage capacity is warranted. <br /> 2. Cross Sectioning or Grid Method - For the ponds that normally contain water year <br /> round, or where a reference stake could not be detected below the water surface, <br /> a survey cross section or grid method will be used to determine sediment volume <br /> using accepted engineering practices. The survey would be performed on an <br /> annual basis to determine sediment storage capacity and to determine when <br /> corrective action is required to restore adequate pond capacity. <br /> 3. Aerial Mapping - An alternative method is photogrammetric mapping that would <br /> create an accurate 1" = 50' topographic map with 2 ft. contour intervals to <br /> determine the remaining storage volume beneath the principal spillway. This <br /> method could be used as the sole method for dry ponds or used in conjunction <br /> with the surveyed cross section method for ponds partially full of water. Once <br /> the topographic map has been generated, accepted engineering methods will be <br /> utilized to perform the volumetric calculations. <br /> Corrective action required to restore adequate sediment storage capacity may include the <br /> following: <br /> 1. Raise the spillways and redesign the pond in order to restore adequate storage <br /> capacity 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 a topsoil-like <br /> medium and utilized in reclamation. The material that is not suitable for a topsoil-like <br /> medium will be graded into the surrounding topography within the disturbance area, <br /> topsoiled, and revegetated in accordance with Peabody's approved reclamation plan. <br /> 13-5 Revised 04/11/88 <br />