2011-06-20_REVISION - C1981019 (5)

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RULE 2 PERMITS about 6,200 feet in length and has a maximum sustained slope of 8.3 percent. The East Haul Road is about 5,200 feet in length with a maximum slope of 5.8 percent. These roads are also specifically designed to meet Rio Tinto internal road design guidelines while minimizing additional disturbed area and preventing environmental damage. Other design requirements are presented in the Construction Notes section of Map 25D and are summarized below. Cross fall slopes between centerline and road shoulders shall be between 1 and 2 percent as directed by the field engineer. Upon completion of these three roads, the entire running surface of the road shall be surfaced with approximately 1.0 to 1.5 inches of rock or crushed gravel for traction. Additional crushed gravel surfacing shall be reapplied as necessary throughout the life of the roadway. A 6 foot high berm shall be used at all locations where the roadway is elevated. Cut slopes shall be 0.5H:1 V or less when completed in competent rock. Elsewhere, cut slopes in unconsolidated materials shall be laid back at 1.5H:1V or less as directed by the field engineer. Drainage from haul road shall be directed to the pit(s) wherever possible. A ditch shall be installed at toe of all cut slopes. If needed, temporary erosion control measures shall be implemented during construction to minimize sedimentation and eresicn until permanent control measures can be established. The field engineer shall determine the need for control measures during construction. Such temporary and permanent control measures would include silt fences, straw bales, straw wattles, rock check dams, or other measures such as downstream sediment ponds. Many truck routes within the Collom area will be constructed as in -pit truck routes, due to their location within existing pit limits. Therefore, all truck routes constructed during the permit term within the immediate mining area are exempt from any construction specifications, since roadways within the immediate mining pit area are not included within the code of Colorado Regulations Definition of "road" (Rule 1.04(111)). Out of pit haul roads such as those identified on Map 23B will be designed and constructed in accordance with Rule 4.03. In general, mining area truck routes are built with a crown, are ditched on either side for proper drainage, have berms of at least axle height on outside (downslope) exposures, and only exceed grades of nine percent for distances of less than 100 yards. Typical truck routes are from 80 feet to 120 feet wide, are surfaced with sized crushed rock, and are maintained with motor graders. In order to obtain access to the Little Collom Sediment Pond, an existing two track road will be upgraded as shown on Volume 20, Exhibit 25, Item 1. This road, which is about 6,600 feet in length, has been designed to meet the applicable portions of CDRMS Rule 4.03.2 for Access Roads. It is specifically designed to meet the minimum design requirements while minimizing additional disturbed area and preventing environmental damage. The road ties to existing county road 32. The completed road will have a width of 12 feet. Use of road is for routine environmental monitoring and occasional pond maintenance only. Typical road use would consist of one trip per week by a light use vehicle using one way travel and low speed. Horizontal alignment will exactly follow existing two track road alignment and is consistent with existing natural topography. Overall grade of the road is approximately 6 %. The existing two -track road will be hard bladed to remove all vegetation and rutting and to provide a level surface across roadway, with maximum cut and fill depths of less than 2 feet. Following blading, a minimum 4 inch thickness of clean, minus 2 inch gravel shall be placed and compacted across the entire width. A triangular V -ditch approximately 18 inches in depth shall be cut on the uphill (Eastern) side of the completed roadway. Routine road maintenance will consist of occasional blading and drainage control. Any outslopes created from the construction of this access road will be seeded with the mix listed above post construction. 2.05.3 (4) Operation Plan — Ponds, Impoundments, and Diversions Collom — Rule 2, Page 97 Revision Date: 5/20/11 Revision No.: PR -03