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RULE 4 PERFORMANCE STANDARDS <br /> rtp>•'*t'iwe;.d,Yz e... :.u'ti:' ,.p.tw°K**.,^ a..:� '+rm Ya»a+r �'G . . .'R�v�'tv<.ya:yi »yarmabe'�ir asYt+rbw'iWlt�°i ,^. <br /> With a few exceptions, Colowyo plans to have all surface runoff from the disturbed area pass <br /> through sedimentation ponds. Sedimentation ponds are discussed in detail under Section 4.05.6, <br /> and their location is shown graphically Map 12 and 12A. <br /> Exceptions include such areas as topsoil stockpiles located along the paved haul road,East Taylor <br /> holding pond and pump station, raw and potable water lines, and railroad loop. Erosion and <br /> sediment control is achieved by protection with vegetation or rock. <br /> The Administration and Security buildings have associated paved parking areas which generate no <br /> sediment. <br /> Colowyo employs various methods to manage water which periodically collects internal to the <br /> mining operation and does not reach sedimentation ponds. various sumps, ditches, pumps, hoses <br /> and pipes, etc. will be employed to control water within pits and/or route water between pits. The <br /> ultimate destination of such water will be for operation's use (dust control, etc.), evaporation or <br /> seepage into the backfilled spoil areas. <br /> In addition to the mining, reclamation and treatment methods described and referenced in this <br /> Section, further protection of the hydrologic balance will be established by an on-going plan for <br /> monitoring potential changes in surface water quality and quantity and groundwater quality. This <br /> monitoring plan is described under Section 4.0-5.13 and the monitoring locations are graphically <br /> shown on Water Monitoring Sites for Permit No. CO-019-81 (Map 10B). Excess spoil valley fill <br /> areas are located downdip of mining and reclamation areas and periodic monitoring for seeps and <br /> springs and periodic monitoring of piezometer wells will detect the formation of spoil springs. <br /> 4.05.2 Water Quality Standards and Effluent Limitations <br /> The plan for protection and control of drainage and sediment described in 2.05.6 provides that <br /> surface drainage from the disturbed area within the permit area will be passed through <br /> sedimentation control structures. All ponds will be constructed and maintained to contain or treat <br /> the volume design for a 10-year, 24-hour precipitation event. The accumulation of sediment in the <br /> ponds will be monitored quarterly. In addition,grab samples of water,as required,will be collected <br /> from pond discharges to measure the effectiveness in meeting the applicable Colorado and Federal <br /> water quality standards. <br /> The proposed sedimentation ponds have been designed and will be constructed and maintained to <br /> effectively trap sediment from runoff resulting from precipitation events up to and including the <br /> 10-year, 24-hour precipitation event. <br /> Drainage from the mining area,after treatment in sedimentation ponds,is not anticipated to exceed <br /> the effluent limitations of any federal or Colorado agency requirements. Baseline groundwater <br /> quality is discussed in Section 2.04.7. No acid mine drainage of pH equal to or less than 6.0 is <br /> expected. <br /> Rule 4 Performance Standards 4-8 Revision Date: 12/20/19 <br /> Revision No.: TR-135 <br />