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Pond embankments, slopes, spillways and construction methods have been designed according to <br />such engineering factors as structural integrity and ability, slope and surface stability, adequacy <br />in height, size and shape to provide sufficient volume for sediment and detained water and <br />selection of proper spillways and outlet devices, passing of design storm events and proper <br />outflow rates. <br />The purpose of tite sediment ponds is not only to provide a final measure to prevent additional <br />contributions of sediment outside the permit area, but also to provide a means of compliance <br />with all applicable effluent limitations, especially with respect to total suspended solids. The <br />effluent quality is regulated by Section 4.05.2 and by Chimney Rock Mine's National Pollutant <br />Discharge Eliminations System (NPDES) Permit (Exhibit 8). <br />The engineering design parameters incorporated into the construction of the sedimentation <br />control structures are described in Exhibit 7, Sediment Control Design Criteria. Other <br />engineering design parameters for the various interceptor ditches, riprap, and terraces are also <br />depicted in Exhibit 7, Sediment Control Design Criteria. No permanent impoundments are <br />planned for the site. <br />Three small area exemptions (SAE) have been approved on the mine site as depicted on the <br />Drainage Control Map (Map 8). These areas include the reclaimed explosive storage area (as <br />approved in Minor Revision Number 35) the AVF area below Pond 002 (as approved in <br />Technical Revision Number 20) and the Pond 005 sediment cleanings (as approved in Technical <br />Revision 27). Facility design information associated with the sediment trap and the Pond 005 <br />sediment cleanings (TR-27) approved in TR-20 is contained in Exhibit 7. <br />To accommodate drainage in the East Pit reclaimed area, permanent diversions have been <br />installed as shown on the Drainage Control Map (Map 8). Design of these structures is contained <br />in the Addendum to Exhibit 7. <br />Topsoil (Removal and Storag, <br />Drainage Control Map (Map 8) depicts the locations and volumes of soil stockpiles. Kaiser <br />proposes to limit the amounts of topsoil to be replaced in order to insure placement of soil over <br />the entire area disturbed as a result of mining operations. Placement of approximately 6 inches of <br />soil over the entire mined area was found to be acceptable. Topsoil stockpile locations include <br />the following: <br />Stockpile A - 10,000 cubic yards <br />Stockpile A will be retained for reclamation of the sediment ponds. All other stockpiles have <br />been utilized for reclamation of the surface facilities and Revision 1 mined areas during the fall <br />of 1991. <br />,gP~.oY~r ~,/~~/d¢ T~-j4 <br />2.05-3 Rev. 10-26-04 <br />