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III. Hydrologic Balance <br /> A. Water Quality Standards and Effluent Limitations <br /> There are no currently permitted small are exemptions located within the New Horizon <br /> Mine Permit. <br /> B. Diversions and Conveyance of Overland Flow <br /> ERMR uses various types of structures to control runoff from disturbed areas. In <br /> addition, surface mining activities are planned and conducted to minimize disturbance <br /> of the prevailing hydrologic balance in both the mine plan and adjacent areas in order <br /> to prevent long-term adverse changes in the hydrologic balance. Sediment and runoff <br /> control methods include diverting runoff through disturbed areas using stabilized earth <br /> channels, culverts or pipes so as to prevent, to the extent possible, additional <br /> contributions of sediment to stream flow or to runoff outside the permit area. ERMR <br /> also uses straw dikes, silt fences, small V-ditches, riprap, mulches, check dams, <br /> vegetative sediment filters, temporary cover crops and sediment traps that will reduce <br /> overland flow velocity, reduce runoff volume, or trap sediment. Collection ditches, <br /> culverts, and diversion design parameters are described in Section 2.05.3(3) Mine <br /> Facilities and detailed design information is given in Attachment 2.05.3(3)-l. Map <br /> 2.05.3(3)-1 illustrates the topography, ponds, and ditches. <br /> C. Stream Channel Diversions <br /> There are no stream channel diversions proposed for the NHM. Calamity Draw flows <br /> undisturbed parallel to the NHM southern boundary, while Tuttle Draw parallels the <br /> northern boundary. <br /> D. Sedimentation Ponds <br /> ERMR uses sediment ponds to prevent additional contributions of sediment to <br /> streamflow or runoff outside the permit area due to mining disturbances. Sediment pond <br /> locations are shown on Map 2.05.3(3)-l. Sediment pond design, construction and <br /> maintenance are described in Section 2.05.3(3) Mine Facilities. The pond designs and <br /> runoff calculations for the permit area ponds are shown in the following attachments: <br /> Pond 012 Attachment 2.05.3(3)-12 and 13, Pond 13 Attachment 2.05.3(3)-6, Pond 015 <br /> Attachment 2.05.3(3)-24, Pond 16 Attachment 2.05.3(3)-36 and Pond 18 Attachment <br /> 2.05.3(3)-35. <br /> Alternative design criteria and specifications have been approved for use in sediment <br /> pond design and/or construction. This decision is based on a thorough analytical <br /> demonstration by a qualified professional engineer that the resulting sediment ponds <br /> will be as environmentally sound and structurally stable taking into consideration <br /> 23 <br />