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2. Excavate the ponding area and restore or enlarge the sediment storage capacity. <br />The material excavated will be tested to determine its suitability as topsoil and utilized in reclamation, or <br />graded into the surrounding topography within the disturbed area, topsoiled, and revegetated in <br />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 4.05.6(3)(b). All sedimentation ponds will be inspected <br />quarterly under the supervision of a Registered Professional Engineer and reported to the CDRMS. A <br />professional engineer will certify each sedimentation pond and impoundment annually. <br />Based on SP's previous experience at the Seneca IIW Mine, pit dewatering will be primarily a seasonal <br />occurrence. The dewatering process will be a sporadic operation -controlled occurrence depending on <br />various factors which may include the location of the pit inflows, the location of standing water in the pit, <br />or the location within the pit of overburden and coal removal operations. When pit dewatering is <br />required, the anticipated dewatering rate will be in the range of one to two cubic feet per second, or less. <br />Any dewatering discharges will be directed to a pond. The discharge from the pit dewatering will be <br />controlled, as necessary, with an adequate energy -dissipater (ie: rock riprap, geotextiles, metal or concrete <br />energy dissipater boxes, etc.) or discharged onto non -erodible bedrock material. Pit dewatering will have <br />an insignificant impact on the proposed pond. The pit dewatering will be sporadic versus continuous. <br />The flow rate of one to two cubic feet per second or less, compared to the design 10 -year, 24-hour peak <br />inflow rate, is very insignificant. In addition, all discharge from ponds will be in accordance with <br />applicable discharge permits. <br />All sedimentation ponds and impoundments will be maintained until the disturbed areas are reclaimed and <br />the vegetation success requirements of Tab 22 are met, the untreated drainage from the disturbed area <br />ceases to contribute additional suspended solids above natural conditions, and the drainage leaving the <br />pond meets applicable State and Federal water quality requirements, if any, for the receiving streams. All <br />temporary ponds will be removed when the appropriate sections of the regulations are satisfied. <br />Permanent impoundments will be reevaluated prior to bond release and any appropriate remedial <br />construction (ie: modification of the discharge to facilitate through -flow of storm discharges) performed <br />to satisfy the appropriate sections of the regulations. Prior to submittal of any final bond release request, <br />SP will submit a complete Technical Revision demonstrating that each permanent impoundment meets <br />the requirements of Rule 4.05.9(13) for permanent impoundments. SP will inspect any permanent <br />impoundments on an annual basis (typically after spring runoff) and will repair any significant damage to <br />or erosion of pond embankments and inlet/outlet structures. If the lands associated with any permanent <br />impoundments are transferred or sold, a similar commitment for regular inspection/maintenance will be <br />included in the transfer/sale agreements. <br />When sedimentation ponds are removed, the affected land will be regraded and revegetated pursuant to <br />the CDRMS regulations, Section 4.05.17, and the approved reclamation plan. <br />Design Methodology The precipitation runoff (peak flow and volume) is estimated using the Soil <br />Conservation Service (SCS) triangular hydrograph techniques as described in Design of Small Dams <br />(U.S. <br />RN06 5 12/01/16 <br />