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<br />Ms. Christine Johnston <br />Mountain Coal Company <br />Page 4 <br />April 14, 1997 <br />2.05.3 Operation Plan -Permit Area <br />2.0_ 5.3(3) Mine Facilities <br />18. As noted in Comment 55, below, MCC has not provided adequate narrative describing <br />each of the proposed mine support facility structures. There are a number of facilities <br />shown on the "General Arrangement of Site Layout Showing Sinking Facilities and <br />Services" map which are not discussed in the narrative. <br />19. The water handling system proposed in the March 7, 1997 submittal is generally <br />acceptable. However, it is the Division's understanding that the use of sumps within the <br />West Elk Mine will be formally proposed for approval with the forthcoming Probable <br />Hydrologic Consequences (PHC) Technical Revision. <br />20. The Division still has a concern about surface runoff from the proposed shaft site running <br />down the slope and into pond SG-1. MCC had stated that this situation had been resolved <br />with the redesign of the shaft site drainage area. However, examination of Drawing <br />E611201A does not show how runoff will be redirected from the slope leading to pond <br />SG-1. Please provide a further explanation of MCC's position. <br />21. The Division has no further concerns. MCC added culverts CSLY-5 and CSLY-(0 to the <br />drainage plan. Revised Sedcad designs and revised Maps 53B and 54B were included in <br />the March 7, 1997 submittal. <br />22. MCC's submittal of the RFP plan set, accompanied by a design structural stability <br />analysis of the Tensaz Fabric and Block retaining walls does allow the Division additional <br />detail regarding the intended earthwork on vazious cut and fill slopes within the SGFA. <br />The designs appear to be performed in accordance with standard fabric wall design <br />methodology. One problem continues to exist. In keeping with its slope stability <br />analytical methodology applied throughout its analyses of MCC's proposed "post- <br />construction" (mine plan) and "post-reclamation" (reclamation plan) configurations, Golder <br />Associates has assumed all bedrock and native soils have one azbitrazy pair of material <br />strength pazameters. As is addressed at length in comments hereafter regarding MCC's <br />response to Item #71, the Division does not believe this methodology to be appropriate. <br />In the case of those retaining structures installed adjacent to original ground cut slopes <br />this suggests that the structural analysis may also be flawed. Please provide appropriate <br />information to demonstrate to the division that embankment stability will result. <br />