REV95542 - Laserfiche WebLink

Home Browse Search

• • 1111111 1111111 Pond embankments, slopes, spillways and construction methods have been designed according • to such engineering factors as structural integrity and ability, slope and surface stability, adequacy in height, size and shape to provide sufficient volume for sediment and detained water and selection of proper spillways and outlet devices, passing of design storm events and proper outflow rates. The purpose of the sedimentation ponds is not only [o provide a final measure to prevent additional contributions of sediment outside the permit area, but also to provide a means of compliance with all applicable effluent limitations, especially with respect to total suspended solids. The effluent quality is regulated by Section 4.05.2 and by the Chimney Rock Mine's National Pollutant Discharge Eliminations System (NPDES) Permit (Exhibit 8.) The engineering design parameters incorporated into the construction of the sedimentation control structures are described in Exhibit 7, Sediment Control Design Criteria. Other engineering design parameters for the various interceptor ditches, riprap, and terraces are also depicted in Exhibit 7. Sediment Control Design Criteria. No permanent impoundments are planned for the site. Three small area exemptions (SAE) have been approved on the mine site as depicted on the Drainage Control Map (Map 8). These areas include the reclaimed explosive storage area (as approved in Minor Revision Number 35) the AVF area below Pond 002 (as approved in Technical Revision Number 20) and the Pond 005 sediment cleanings (as approved in Technical Revision 27). Facility design information associated with the sediment trap and the Pond 005 • sediment cleanings (TR-27) approved in TR-20 is contained in Exhibit 7. The Stollsteimer Creek crossing culvett is a temporary structure and is planned to be removed during reclamation activities proposed for the fall of 1991. Topsoil (Removal and Storage Drainage Control Map (Map 8) depicts the locations and volumes of soil stockpiles. Kaiser proposes to limit the amounts of topsoil to be replaced in order to insure placement of soil over the entire area disturbed as a result of mining operations. Placement of approximately 6 inches of soil over the entire mined area was found to be acceptable. Topsoil stockpile locations include the following: Stockpile A - 10,000 cubic yards Stockpile A will be retained for reclamation of the sediment ponds. All other stockpiles have been utilized for reclamation of the surface facilities and Revision 1 mined areas during the fall of 1991. 2.05-3