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Mr, Rich Atkinson <br />-5- <br />May 12, 1987 <br />a. On Map 35, it appears that a hill will be created in the <br />post-mining topography at the northern edge of the pit. <br />Colowyo should briefly discuss the impacts of this <br />configuration, such as the increase of spoil side slope length <br />on potential erosion. <br />b. The operator should substantiate how the average operating <br />grade for pit regrading was estimated. In addition, the 6.:- <br />equipment utilization factor seems high fora 3 shift <br />operation. The dozer operator correction factor should be .75 <br />rather than .80 Lastly, the material correction factors <br />should be adjus~ed to reflect the difference between highwall - <br />and spoil earthwork. <br />c. For rough grading calculations, the operator mast substantiate <br />the use of a 1.04 job factor, including a listing of each <br />component of that factor. <br />d. Topsoil replacement costs should be entirely recalculated. <br />Cycle times for the 988-B loader are low, resulting in <br />overestimation of productivity. Truck capacity of the 773-B is <br />low, resulting in underestimation of productivity. Job factors <br />should be adjusted to reflect a 3 shift operation. Lastly, it <br />does not appear that the truck-shovel team productivity was <br />properly calculated. <br />e. Reclamation costs for all channel reestablishment should be ' <br />added, including riprap material and placement. <br />f. It should be noted that if additional space is required in this <br />volume, much of the information in appendices B 8 C could be <br />removed by directly referencing the appropriate cost guides. <br />Rule 4 - Performance Standards <br />1. Colowyo should be aware that the Division must be notified prior to <br />using any sediment pond cleanings as topsoil. Division approval <br />should be included in the statement on page 4.05-7. <br />2. The Division has reviewed the designs for reestablishment of <br />permanent stream channels on the site, and has noted that no <br />transition zones are provided for upstream and downstream junctures <br />of protected and unprotected channel segments. For areas not <br />presently completed, a design must be submitted which includes <br />transition zones of appropriate length containing a double thickness <br />of riprap. This is required to protect the riprapped channel <br />sections from undercutting. <br />In addition, the present channel design states that allowable <br />velocities for unprotected channel segments is 5.0 to 5.5 fps.. <br />This eouates (with water carrying sediment) to a cobbly channel <br />bottom. Coiowyo should describe the material that will be in the <br />unprotected stream segments and its ability to withstand these <br /> <br />