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J. J. Dudash - 4 - August 13, 2003 <br />17. DMG -Please indicated those items included in conformance with Rule 4.10.3(3) on the detailed <br />design of the excess material stockpile. <br />BRL -Not applicable. There are two terraced ditches on the excess material stockpile. <br />Additionally, excess rock will be utilized to plate the out slope of the excess material stockpile. <br />18. DMG -Please include all construction requirements under Rule 4.10.4 on the detailed design the <br />excess material stockpile. <br />BRL -Not applicable. <br />19. DMG -Please reference, including location, of the geotechnical stability analysis for the B-seam <br />excess material storage stockpile that demonstrates a safety factor of 1.5. If not included in the <br />section of other geotechnical analyses, suggest it be part of the detailed design package. <br />BRL -Enclosed is a Geotechnical Engineering Study for the B-Seam Portal Bench dated July 30, <br />2003. The report is to be inserted into Volume VII, Tab 10. <br />Surtace Water Hvdroloav <br />20. DMG - It is stated on proposed page 2.05-45 that Surtace water will be diverted around the B- <br />seam excess material stockpile. This is also required under Rules 4.10.3(2) and 4.09.2(7). <br />However, Map 21-2 shows that upland water is not being diverted around the stockpile. Please <br />provide appropriate designs, using the 100 year-24 hour event as required in Rule 4.09.2(7), and <br />map modifications that provide for the diversion of upland runoff around the B-seam excess <br />material stockpile. <br />BRL -The quoted rules are not applicable. Additionally, the D-Seam portal bench and the light <br />use road that extends to the east from the D-Seam portal bench significantly reduce the drainage <br />area above the excess material storage area. <br />21. DMG -Rule 4.09.2(7) requires that runoff from the surface of the B-seam excess material <br />stockpile is diverted to stable channels that are designed for the 100 year-24 hour event. <br />However, as shown on proposed pages Exh-8-65 and Exh-8-68, ditches D-C5 and D-C10 were <br />designed using the 10 year-24 hour precipitation event. Please provide revised ditch designs for <br />ditches D-C5 and D-C10 using the 100 year-24 hour precipitation event. <br />BRL -Rule 4.09.2(7) is not applicable. The ditches D-CS and D-C10 were designed using the 10 <br />year-24 hour event which is consistent with all of the drainage features designed on the entire <br />mine site. <br />22. DMG -Please provide Sedcad designs that demonstrate the proper sizing of the riprap that will be <br />used in the riprapped channels proposed in this revision. <br />BRL - Riprap sizing was added to the V-Ditch design tables, pages Exh8-29 and 29i. The <br />SEDCAD utility program was used to size rip-rap for ditches with a flow velocity of 6.0 fUsec or <br />greater. The Simon/OSM -Steep Slope Design and Pader Method were both used to size the <br />riprap. Where the Pader Method was used, 3" was added to the riprap size. <br />23. DMG -Since it affects surface water runoff, will there be guard rail or a berm on the outside edge <br />of the B-seam portal bench and the coal preparation plant ? <br />BRL -There will be a berm. <br />