2008-09-16_PERMIT FILE - C1982056A (4)

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Due to the fact that the pH is being elevated, it was decided to have sulfuric acid available in the event a pH adjustment was needed prior to the effluent discharging from the system. The chemical and equipment for this procedure is housed in the chemical storage building located on the west side of the west cell as shown on Map 32. • This system will be used only if the effluent approaches the pH discharge limitation of 9.0. In 2006, the sodium hydroxide system was replaced with an electro-coagulation system which achieves the same result through ionization and agglomeration of particulate iron. The treatment ponds and associated surface facilities and systems will be removed and disturbed areas reclaimed when no longer needed for treatment of mine- water discharge. Reclamation plans for this facility are summarized on page 2.05-105.1. EMD - lORT Dewatering Wells 1 and 2 and 6MN Mine Water Transfer Line 1MR07 224 MR08 2281 The EMD Dewatering Well installation consists of two dewatering wells and associated "ancillary equipment and structures (existing); and treatment facilities, settling ponds, and discharge point (permitted for possible future construction). The EMD (or l ORT) Dewatering Wells 1 and 2 draw from the sump developed off the lORT entry (refer to Map 23, Mine Plan, for the location of the sump). An access/light-duty road was constructed to the borehole site from RCR33. The initial 1,600 feet of this road required new construction, while the remainder of the road (3,000 feet) involved upgrades to the existing ranch road. For definition purposes, the beginning 700 feet is an access road and the remaining 3,900 feet is a light-duty road. The location of the access road is shown on Maps 17 and 18. The location and alignment of the initial 1,600 of the road differs slightly from the original proposal in order to provide for greater visibility and safety at the junction with the existing road. During construction of the road, approximately 6,800cy of soil material was windrowed to the side of the road. This volume is based on constructing a road 4,600 feet long and 20 feet wide, and salvaging soil material to a depth of 24 inches. The stockpiled soil material was seeded with the pastureland seed mixture at the specified rate. The finished width of the road is approximately 12 feet, and it is surfaced with approximately 9 to 12 inches of 6-inch pit run gravel and 3 to 4 inches of 1 %2-inch road-base or crushed rock. Culverts were installed at minor drainage crossings along the road alignment. Design calculations for these culverts, numbered EMD-1 through EMD-4, are provided in Exhibit 8a, Culvert Sizing -EMD Dewatering Facility Access Road. The EMD Dewatering Well installation consists of a graveled pad area, 14-inch (Well 1) and 12-inch (Well 2) cased wells with down-hole pumps and 6 or 8-inch discharge lines, the pump and control building, two power distribution transformers and powerline, the transfer pipeline, and associated soil stockpile and ASC drainage controls. The pad area is approximately 100 x 240 feet, and during well drilling operations, two 10 x 10 x 50 foot mud pits were excavated. On completion of drilling, the mud pits were backfilled with excavated material. Nominal 17.5-inch diameter boreholes were drilled into the sump area, approximately 1,350 feet of 12 or 14-inch metal casing was installed in the drillholes, and grouted along its entire length. Submersible pumps capable of pumping 550 gpm (Well 1) and 700 gpm (Well 2) were installed in the casing. To complete well installations, an 8-foot length of 8-foot diameter corrugated metal pipe with lid was placed over each borehole as a surface casing/access manhole. The material excavated from the surface casings was spread over the pad. The control building is approximately 10 x 10 x 10 feet, and sets on a concrete pad 10 x 10 x 0.5 feet. Substation 2, at the site, consists of two transformers and associated switch-gear on concrete foundations, surrounded by a graveled pad with a 7-foot high security chain-link fence around its perimeter. The existing powerline, approximately 1.5 miles in length, ties Substation 2 to Substation 11, on the 6MN Road. The 6 and 8-inch discharge lines from the submersible well pumps connect to the 8 and 12-inch HPDE Mine Water Return Lines to FCM-2 (Well 1) and the 12-inch HDPE connector line, which ties from We112 to the Mine Water Return Line near the junction of this line with the 6MN Mine Water Storage Reservoir Transfer Line. HDPE pipe is extremely flexible. With a cold bend radius of 160 inches, the pipe can be offset 80 inches vertically over a length of 160 inches. This greatly exceeds any potential offset due to surface subsidence. The current transfer pipeline, and any future piping to treatment ponds, will be buried at a depth of 5 to 6 feet to minimize freezing problems. The existing Mine Water Return Line is approximately 7,300 feet long. The connector line from We112 will be approximately 1,000 feet long. Any future feed line for the water treatment ponds would be approximately 4,300 feet long. MR08-228 2.05-77.1 03/06/08