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<br />29. Pages 9 through 11 list the sedimentation ponds for which designs have been submitted. <br />Exhibits show that in addition to We two ponds listed, three other sedimentation ponds <br />will be construMed. SCC should include language to the effect that the other three ponds <br />will be constructed in subsequent permit terms, and that designs would be submitted prior <br />to construction <br />30. Page 17 states that road ditch sideslopes will be 1.5:1 or flatter; page 13-7-1 says the <br />sideslopes will be 3:1; pa a 13-7 commrts to 5:1; and Exhibit 13-9 shows 3:1 on one srde, <br />and 2:1 on the other. Please make any necessary revisions so that the proposed road <br />ditch sideslopes are clear and consistent. <br />31. Page 22 states that SCC proposes to leave sections of haul roads as permanent access <br />roads. If SCC wishes to retain any roads, a detailed description of the post mine road <br />and a reqquest from the landowner must be submitted to the Division, in accordance with <br />Rules 4.03.1(7)(a) and 4.03.2(1)(£). <br />32. Page 32 states that waste water will be disposed of in septic systems. Please submit a <br />co of the permit obtained or a written waiver thereof from the Colorado Department <br />of Health for installation of a septic system. <br />33. Page 13-1-6, Table 2 is a listing of Seneca II-W soils information If this table should also <br />apply to the Yoast Mine, it should be updated, as it does not include a listing of all soils <br />ma ped in the Yoast Mine area. Please either revise the table or include an additional <br />' '' table that would pertain to the Yoast Mine. <br />_. n <br />r 34. Modelling of sediment control structures was based on a worst case scenario assumed by <br />SCC, with which the Division agrees. Should SCC make changes to the mining sequence <br />or total disturbance areas, appropriate revisions to sediment control structures would be <br />required. <br />35. Attachment 13-1, Addendum 2 is a summary of typical SEDCAD+ inputs for ditches and <br />culverts. This document is identical to Addendum 1, for ponds and impoundments. <br />Therefore, some in uts are described as "not applicable to impoundment designs." Please <br />revise Addendum 2 so that it applies to culverts and ditches, as described. <br />36. The ditch designs provided in Attachment 13-2 are based on vegetated channel <br />conditions. When the ditches are initially constructed, vegetation will not be established. <br />For all three diversion ditches, it is apparent that flows through the bare channels will <br />be erosive. Please provide a plan for temporary stabilization of the channels until <br />vegetation is established. <br />37. Attachment 13-3, page 1 says that excavated suitable material will be used in the <br />embankment construction of Pond 10, but that most of the embankment material will <br />come from the facilities area. One of the conclusions in Attachment 13-5 is that the <br />material in the vicinity of the proposed pond is not suitable for embankment construction <br />since the soils were observed to be soft and deformable. Please revise the construction <br />plan to omit plans for use of excavated material in the embanlanent construction, in <br />accordance wrth recommendations of the consulting engineers. If there is not adequate <br />material available in the facilities area, please indicate where suitable material may be <br />found. <br />38. The Division modelled runoff to Pond 10 and arrived at significantly different results than <br />did SCC. A copy of the results of the DMG model are enclosed. Differences in inputs <br />noted were: <br />M. Altevilla end G. Wendt ~] January 23, 1995 <br />