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1 <br /> Task 3 SURFACE DRAINAGES <br /> Excavated, sorted and stockpiled riprap within the waste borrow area will be transported <br /> and placed within the five (5) post-regraded intermittent drainages as marked on the <br /> drawings. Rock used for placement as drainage riprap will range between six to thirty-six <br /> inches (6" - 36") in size and will be well graded. The subgrade under riprap/rock <br /> placement will be well compacted prior to placement. Riprap will be spread in one or <br /> two lifts evenly across the bottom and sides to armor the drainages without choking the <br /> flow. After placement the riprap surface will be worked to be well-graded with the voids <br /> choked with smaller cobbles and stones. Drainages will be constructed to start a <br /> minimum of ten feet (10) above the backfill/disturbance limit. The tops of the <br /> sideslopes of all drainage ditches will be at least two feet higher than the invert of the <br /> ditch. It is anticipated that 2,200 linear feet of drainage ditches will be constructed. <br /> Measurement and Payment <br /> Surface drainages will be measured to the nearest linear foot. Payment for this task will <br /> be paid for at prices established in Item 3 of the Invitation and Bid sheet per lineal foot <br /> installed. Such payment will be considered full compensation for all labor, materials, <br /> equipment and all other items necessary and incidental to the furnishing and placing of <br /> the Surface Drainages as directed and described in the specifications. Payment will be <br /> as this task is completed and approved by the Project Manager. Payment for this task <br /> will be made only for the unit price shown under Item 3 of the Bid Schedule. <br /> Task 4 WETLAND CONSTRUCTION <br /> A drainage network similar to the one that comprises the existing wetland will be <br /> reconstructed at the delineated location alongside Highway 160. The wetland treatment <br /> area for the acid mine drainage will consist of a series of three basins which will measure <br /> approximately 150' long by 40' wide in total. Drainage from the existing drainage pipe to <br /> the wetland will be connected by surface drainage riprap.channels as described above <br /> under Item 3. <br /> The wetland basins will be excavated to a depth of four feet (4) with side slopes of <br /> 1H:1V with top dimensions of approximately 40' long by 30' in width. Excavated <br /> material must be uniformly spread over the adjacent slopes to conform to the regraded <br /> topography. The excavated basins will be filled with a mixture of 70% sand and 30% <br /> aged manure. It is estimated that 373 cubic yards of sand and 160 cubic yards of manure <br /> will be required. The final embankments will have a minimum top width of five feet (5) <br /> with outslopes no steeper than 3H:1V. <br /> Positive outflow from each pond will be provided through spillways. Spillways will be <br /> constructed with a final depth of one foot (1'), a bottom dimension of three feet (3'), and <br /> side slopes of 2H:1V. The spillways will be well compacted prior to armoring with a <br /> twelve-inch (12") layer of four to eight inches (4" to 8") diameter rock. The pond's <br /> spillways will be connected by surface drainage riprap channels as described above under <br /> Item 3. <br /> 7 <br />