2001-12-11_PERMIT FILE - C1981019 (2)

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The pond has been designed to comply with the Board's requirements and provide an additional margin of safety. Detailed data on the pond is listed in Tables 7 and 8. • Work Area Sedimentation Pond This pond illustrated on Figure 11 is constructed in an area adjacent to the work area for providing sedimentation of the runoff from the working area. The working crea is the area occupied by the mine offices, maintenance facilities and yards, and storage yards and bui Idings. The pond was constructed at the beginning of mining activities and has been serving its intended function for some time. The design was checked for compliance with required regulations, and a principal pipe spillway and an emergency spillway were con- stru~cted in the summer of 1980 in accordance with the recommendations to meet the regtired regulations. Detailed data on the pond is listed in Tables 7 and 8. Loa+~out Area Sedimentation Pond This pond illustrated on Figure 12 is constructed in the loadout area for providing sedimentation of the runoff from the loadout area. The pond has been checked for com- pliance ~Nith the Board's regulatiors and meets t:•+ose requirements. in order to provide an additional measure of safety, for insuring sufficient detention time, it is recommendeld that an orifice plate with a 4" diameter orifice be attached to the 8" diameter principal spill- way pipe. This will insure sufficient detention time in the event the pond is filled to the elevation of the principal spillway at the time of a flood event and the valve on the 8" pipe is fully open. Detailed data on the pond is listed in Tables 7 and 8. COP~CLUSION The calculations made for the design and checking of the various features described are ~~ttached as annexures to this exhibit. All features have been designed in accordance with the Federal or State regulations applicable at the time of design. For those features ~- 9