1988-04-11_PERMIT FILE - C1981008A (20)

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Site specific conditions will determine the construction methods and equipment utilized at the time of excavation. Sediment removal and water discharges will be conducted consistent with the approved mining permit, the NPDES permit, and Section 4.05.6(3)(b). All sedimentation ponds will be inspected annually under the supervision of a registered professional engineer and reported to the CMLRD. Based on Peabody's experience at the Nucla Mine, pit dewatering will be primarily a seasonal occurrence. The dewatering process will be a sporadic operation-controlled, occurrence depending on various factors which may include the location of the pit inflows, the location of standing water in the pit, or the location within the pit of the overburden and coal removal operations. When pit dewatering is required, the anticipated dewatering rate will be in the range of one to two cubic feet per second or less. Any dewatering discharges will be directed to the Pond 007 - East Ditch which drains into Pond 007. The discharge from the pit dewatering will be controlled with an adequate energy dissipator (i.e., rock riprap, geotextiles, metal or concrete energy dissipator boxes, etc.) or discharged onto non-erodible bedrock material. This pit dewatering will have an insignificant impact on the proposed Pond 007. The pit dewatering will be sporadic versus continuous. The flow rate of one to two cubic feet per second or less compared to the design 10-year, 24-hour peak inflow rate of 81.5 cubic feet per second is very insignificant. In addition, all discharge from this pond will in accordance with applicable discharge permits. All sedimentation ponds and impoundments will be maintained until the disturbed areas are reclaimed and the vegetation success requirements of Tab 22 are met, the untreated drainage from the disturbed area ceases to contribute additional suspended solids above natural conditions, and the drainage leaving the pond meets applicable State and Federal water quality requirements, if any, for the receiving streams. All temporary ponds will be removed when the appropriate sections of the regulations are satisfied. All sedimentation pond slopes will be protected from erosion where surface runoff enters the ponding area. Monitoring for rills and gullies on pond slopes will be carried out on a periodic basis; the monitoring being geared to those periods after spring snowmelt and during required quarterly pond inspections. 13-6 Revised 09/26/90