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TASK 2 SURFACE DRAINAGES <br /> There will be three drainages constructed at the Sutey Pile: (A) a large diversion around <br /> the base of the pile, (B) a contour trench will be excavated to divert runoff from the upper <br /> portions of the pile to the north, and (C) a downdrain along the front of the pile. <br /> The diversion ditch (Channel A) currently exists, but must be reconstructed in order to <br /> safely pass flows from the refuse pile and from the adjacent drainage area. The diversion <br /> will be 3,500 feet long, 10 feet wide at the base and the top of the side slopes will be no less <br /> than five (5) feet above the ditch invert. Side slopes shall not exceed 3H:1V. Riprap with <br /> a median diameter (D-50) of ten inches (maximum diameter not to exceed eighteen inches) <br /> will be placed in the channel to a depth of twenty (20) inches over a well-compacted <br /> subgrade (see Drawing A). After placement, the riprap surface will be worked to be well- <br /> graded with the voids choked with smaller cobbles and stones. A source of riprap within <br /> the mine site area will be identified by the CONTRACTOR, subject to approval of the <br /> PROJECT MANAGER. The material will consist of durable sandstone or metamorphosed <br /> shale materials. Unaltered Mancos Shale is not acceptable for riprap. <br /> The contour trench (Channel B) will be 200 feet in length, and ten (10) feet wide and no <br /> less than four (4) feet in depth as measured from the base to the top to the cut on the <br /> inside of the excavation. Side slopes will not exceed 3H:1V. The dozer will excavate this <br /> 'IJ shaped cut into the side slope of the refuse pile spoiling the cut material downslope. <br /> The contour trench will be excavated at the location staked in the field by the PROJECT <br /> MANAGER. The contour trench will be staked and excavated so that it follows the contour <br /> of the Sutey Refuse Disposal Area. <br /> An existing downdrain (Channel C) at the south end of the pile must be reconstructed. The <br /> drain will be 800 feet long, five feet wide at the base and the top of the side slopes will be <br /> no less than three feet above the down drain invert. Side slopes will not exceed 3H:1V. <br /> Riprap with a median diameter (D-50) of twelve (12) inches (maximum diameter not to <br /> exceed three feet) will be placed in the channel to a depth of at least eighteen (18) inches <br /> over a well compacted subgrade. After placement, the riprap surface will be worked to be <br /> well-graded with the voids choked with smaller cobbles and stones. A source of riprap <br /> within the mine site area will be identified by the CONTRACTOR, subject to approval of <br /> the PROJECT MANAGER. The material will consist of durable sandstone or <br /> metamorphosed shale materials. Unaltered Mancos Shale is not acceptable for riprap. <br /> Measurement and Payment <br /> Surface drainages will be measured to the nearest linear foot. Payment for this task will be <br /> paid for at prices established under Item 2, Channel A, Channel B, and Channel C on the <br /> Bid Schedule per lineal foot installed. Such payment shall be considered full compensation <br /> for all labor, materials, equipment and all other items necessary and incidental to the <br /> furnishing and placement of the Surface Drainages as directed and described in the <br /> specifications. Payment will be as this task is completed and approved by the PROJECT <br /> MANAGER. Payment for this task will be made only for the unit price shown under Item <br /> 2 of the Bid Schedule. <br /> 6 <br />