2010-05-07_PERMIT FILE - C2006085 (2)

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• Table 2.05.3 -2, Cont. Main Power Lines and Substation Overhead, poles on approx. 200 ft. centers, approximate length 600 ft., 3 conductor with neutral conductor. Substation on surface with 3 each step - down transformers, and 2 each power interrupt units. Fan Power line Overhead, poles on approx. 200 ft. centers, approx. length 2,600 ft., 3 conductor plus neutral. Pole mounted transformers, 3 each, at fan site. Mine Dewatering System 6 in. dia. steel pipe, 2 each x approx. 205 ft. long, from portal to sediment pond. Facility Septic System Septic tanks, 4 each 1500 gal. plastic in series, single leach field design pending. Ponds, I other Treatment Facilities and Diversions Drainage and sediment control for Northfield's proposed surface disturbances will include a sediment pond, ditches, culverts, and small area sediment control structures that will minimize erosion and prevent, to the extent possible, additional contributions of sediment to streamflow or runoff outside the permit area. Proposed drainage and sediment control structures and methods are described below and in the Drainage and Sediment Control Plan (Exhibit V). The Drainage and Sediment Control Plan includes supporting documentation, maps, and diagrams for the proposed drainage and sediment control structures. Northfield is proposing a single sediment pond located adjacent to the mine facilities area. This sedimentation pond, designated Pond 1, will be designed utilizing standard engineering practices to retain the runoff from a 10 -year, 24 -hour storm event plus mine dewatering inflow and effect compliance with all other applicable regulatory standards. The proposed pond will not meet the minimum criteria for designation as a MSHA structure. Pond design criteria and supporting calculations are presented in Exhibit V, including information concerning the size, configuration, and surface conditions affecting runoff within the contributing drainage area. 40 Sedimentation Pond 1 is designed to retain runoff from the main mine facility area. Surface water from this area will be collected and routed to Pond 1 by the North and South Runoff Collection Ditches. Mine 2.05.3 -24 Revised 12/04/09, TR -01