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Ms. Christine Johnston <br />Mountain Coal Company <br />Page 7 <br />April 14, 1997 <br />stated in Rule 4.05.6(3)(d). Pond liners have been known to leak and the extra protection <br />would be desirable. <br />38. The Division requested that the Sedcad designs for pond SG-1 be revised to show that <br />weep holes in the primary discharge structure ran from elevation 6768 to elevation 6774 <br />only. The November 18, 1996 submittal showed weep hole elevations above and below <br />those elevations. MCC has supplied revised Sedcad designs which need further revision. <br />The revised Sedcad elevation-discharge tables, for all three runs, still show weeps holes <br />at elevations above and below those mazks. It is possible that this is a program bug, <br />because, in reviewing the dischazge data in the same table, it does not appear that water <br />is discharged through the weep holes until the water level is above elevation 6768. <br />Nonetheless, please submit new Sedcad runs which show the weep holes at the correct <br />elevations. <br />39. The Division requested that certain elevations be shown on the pond SG-1 drawing. Most <br />of the requested elevations were included in new drawings E611304A and E611306A, that <br />replace the drawing entitled "Sediment Pond SG-1 Plan, Sections, and Details." However, <br />the Division requests that these new drawings show the elevation of the lowest weep hole <br />in the primary discharge pipe. It is not possible to scale this elevation from the drawing <br />because the drawing, E611306A, Detail No. 2, appears to show the elevation as being less <br />than 6767 feet. If this is true, please modify this detail as well. <br />40. The Division had concerns about the decant system of pond SG-l. MCC has revised the <br />decant system, eliminating the 180 degree turn. This appeazs to be a better method. <br />However, in doing so, MCC has also changed the location of the decant pipe inlet. It is <br />now located closer to the pond inlet, cutting the travel distance by about half. The <br />Division would like to comment that this increases the chance of short-circuiting of the <br />pond's sedimentation filtering system. <br />The Division still has a concern about the potential for clogging of the sand filter. MCC <br />has commented that the sand filter decant system has been designed for easy clean out and <br />sand replacement if it does become clogged. Please explain how West Elk intends to clean <br />out the decant system and replace the sand if the system becomes clogged while the pond <br />is filled with water. <br />41. 7'he Division has no further concerns. MCC has committed to using straw bales and silt <br />fences as the primary sediment control structures at the SAES. MCC has submitted a <br />revised letter from Golder Associates, dated February 27, 1997 and included in the March <br />7, 1997 submittal, which states this. In addition, the locations of these sediment control <br />