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~, <br />J.E. Stover & Associates -17- May 31, 1996 <br />Bowie No. 2 Mine <br />please explain the reason why culvert C-13, and its value of <br />1.88 cfs is used for culvert C-B12. <br />45. Please add the data for culverts C-D1, C-E1, C-F1 and the <br />culvert at the base of the gob pile to the Culvert Summary <br />and Minimum Size Requirements table, found on page 26 of <br />Exhibit 8. <br />46. On Map 20, Sedimentation Control Plan, and on Map 21-1, <br />Drainage Plans, please add the annotation to the culvert at <br />the base of the gob pile. <br />47. Please add the annotation of culvert C-F1 to Map 20, <br />Sedimentation Control Plan. <br />48. On page 23 of Exhibit 8, a statement is made that flows <br />greater than 6 fps in ditches are considered to be erosive. <br />The Division would like to state its position that erosive <br />velocities depend upon the type of soil and the amount and <br />type of any vegetation in the ditch. As a general guideline <br />only, the Division has, in the past, used 5 fps as the <br />threshold velocity for erosion. <br />49. On Map 20, Sedimentation Control Plan, please add <br />annotations for ditches D-F1 and D-F2. <br />50. Please add the data for ditches D-D1, D-D2, D-Ei, D-F1 and <br />D-F2 to the V-Ditch Design table, found on page 24 of <br />Exhibit 8. <br />51. The operator has requested, on page 12 of section 4.1.5 of <br />Volume IV, small area exemption status for the coal waste <br />pile topsoil stockpile and the coverfill stockpile. However, <br />no designs have been submitted, pursuant to Rule 4.05.2(3). <br />Please submit such designs, after which the Division can <br />determine whether small area exemption status is <br />appropriate. In the designs, please account for the fact <br />that the two areas seem to be placed at the bottom of <br />drainage watersheds, which could result in significant <br />erosion due to runoff from a storm event. <br />52. Referring to Map 5-1, Vegetation Sample Locations, in <br />Exhibit 5, and the photographs in Exhibit 5, it appears that <br />most of the vegetation sampling sites are located within the <br />most heavily vegetated area of the general site. <br />Consequently, less heavily vegetated areas lying to the <br />east, but still draining to mine ponds, may be under- <br />represented in the sampling. If you disagree with this <br />assessment, please explain. If you agree that the assessment <br />