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29 <br />(3) Sized using 2.4 Ft. of head on pipe (HW/D=1.8), HW/D Scale No. 3 <br />(4) Culverts 23 & 24 are inlets culverts to culvert 25. Culvert 25 was sized using the Hazen- Williams <br />formula Exhibit 19, West Portal Data C21 through C25 <br />(5) Sized using 3 Ft. of head on pipe (HW/D=1.5), HW/D Scale No. 1 <br />(6) As Built 03/27/88 SDM <br />(7) 100 -Year 24 -Hour peak discharge. Temporary culverts installed as needed <br />(8)** Temporary culverts installed when required for site assess, then removed. <br />Sediment Ponds are inspected and an inspection report issued quarterly as required by Rule 4.05.9(17). <br />An annual inspection is also completed as required by Rule 2.05.9(15). The annual inspection includes a <br />differential level survey to determine water and sediment levels to document available storage capacity <br />and determine if sediment clean-out is required. If water levels preclude a determination of sediment <br />accumulation then the ponds shall be monitored and surveyed as soon thereafter as practical. <br />To facilitate dewatering surface water control ponds 7 and 8 to enable sediment cleanout, a temporary <br />pumping/piping system will be set up to pump water that cannot be discharged into the Purgatoire <br />River from pond 7 and pond 8 to pond 6. The pipeline from pond 7 will be run directly to the adjacent <br />pond 6. The pipeline from pond 8 will be run across the highway and the Purgatoire River along the <br />elevated RDA Refuse Conveyor as spill prevention protection exists at both crossings. If pond 6 does not <br />have sufficient capacity to hold all the water, the excess water will be pump from Pond 6 to the Allen <br />Mine East portal seals to gravity flow into the sealed and abandoned underground workings. This <br />system will be dismantled when cleanout has been completed. <br />Table 23 provides design criteria for sediment pond construction and maintenance. In addition five <br />containment basins provided localized sediment control for small areas within the mine disturbance <br />area not reporting to sediment ponds. Design criteria for these facilities can be found in Exibit 19, <br />Volume 2 Item 5. As -built drawings and stage storage curves useful in evaluating requirement for <br />sediment removal can be found in Exhibit 32. <br />Section 2.05 TR -71 08/08/2016 <br />