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WFC uses sediment ponds to prevent additional contributions of sediment to <br />streamflow or runoff outside the permit area due to mining disturbances. Existing <br />and proposed sediment pond locations are shown on Map 2.05.3(3)-l. Sediment <br />pond design, construction and maintenance are described in Section 2.05.3(3) <br />Mine Facilities pages 2.05.3(3)-10 through 25 of the permit application package. <br />The pond designs and runoff calculations for the permit area ponds are shown in <br />the following attachments: Pond 007 Attachment 2.05.3(3)-2; Pond 008 <br />Attachment 2.05.3(3)-4; Pond 009 Attachment 2.05.3(3)-5; Ponds 10 & 13 <br />Attachment 2.05.3(3)-6; Pond Oll Attachment 2.05.3(3)-14; Pond 012 <br />Attachment 2.05.3(3)-12 and 13; and Pond 014 Attachment 2.05.3(3)-11. <br />Pond 010 has an approved design but has not yet been built. Ponds 015 and 016 <br />are proposed in the western edge of the permit area but have not yet been fully <br />desiplleu. ronus 007 aiiu 008 are the only ponds mat wiil remain as permanent <br />impoundments after reclamation. The approved demonstrations to allow retention <br />of Pond 007 and 008 are in Attachments 2.05.3(3)-16 and 2.05.3(3)-19, <br />respectively. <br />The sediment ponds described above will treat all disturbed area drainage with <br />exception to the 5 Small Area Exemptions that exist or are planned in the permit <br />area. The designs for these exemptions are shown in Attachment Small Area <br />Exemptions. The areas are also shown on Map 2.05.3(3)-1. No small area <br />exemptions exist on the New Horizon #1 site. The Division specifically grants <br />exemption from the sediment pond requirement for those areas described in <br />Attachment 2.05.3(3)-7. The small area exemptions were originally approved for <br />the entire permit area in the year 2000 under Permit Revision No. 5 and area <br />granted based on conformance with the requirements of Rule 4.05.2(3)(a) and (b). <br />Alternative, design criteria and specifications have been approved for use in <br />sediment pond design and/or construction. This decision is based on a thorough <br />analytical demonstration by a qualified professional engineer that the resulting <br />sediment pond will be as environmentally sound and structurally stable taking <br />into consideration physical, climatological, other characteristics of the site, and <br />will conform to the impoundment performance factor of safety of 1.3. <br />(4.05.6(11)). <br />D. Acid-forming and Toxic-forming Spoil <br />The Division proposes to approve temporary storage of acid- and toxic-forming <br />spoil for more than 30 days. This decision is based on a finding that burial or <br />treatment of these materials within 30 days is not feasible and the delay will not <br />result in any material risk of water pollution or other environmental damage <br />(4.05.8(3)). See Section 2.04.6 for identification, mining plan contingencies, and <br />spoil/mine soil reconstruction plans (respectively) that address acid or toxic spoil <br />horizons. <br />25