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Oxbow A9nring, 1 LC-7ertinirol Reairian 7R-d3 <br />11 Wert Coal Refire F'ariliry <br />TahniralAkquary CommentlRerpanm <br />Se/itembtr 5, 2003 ~ . <br />Poge 12 <br />Re~onse: Potential discharge from the principal spillway discharge pipe is contained within a <br />pipeline which would pass any flows across the existing railroad ditch, under the railroad roadbed, and <br />dischazge at the natural ground surface on the north side of State Highway 133. <br />For the emergency spillway dischazge please refer to the previous response to Comment 12. In <br />addition, based on the SEDCAD+ design calculations, the 25-year, 24-hour peak flows would crest in <br />the pond at an elevation of 6029.72', with a corresponding discharge over the 15-foot wide broad- <br />crested weir of 9.23 cfs. Wifh the emergency spillway invert set at elevation 6029.5, dischazge flow <br />depth would be 0.22 feet, or approximately 2.6 inches. As shown by the detailed design drawings <br />included in the Sedimentation Pond E Embankment Wall Design report (MWH, July 2003), included <br />in. Exhibit 2.05-E4, concrete aprons extend outward at the base of the concrete embankment wall, <br />with the downstream apron extending three feet from the wall. In addition, an 18-inch thick grouted <br />rock splash apron extends from the face of the embankment wall across the base of the existing <br />UPRR drainage ditch. The grouted splash apron extends the entire width of the emergency spillway <br />and over 5-feet beyond on either end. The concrete apron and grouted rock splash apron would <br />prevent erosion at the dischazge point for any flow over the emergenry spillway. The grouted rock <br />splash apron would also serve as an energy dissipater to reduce initial flow velocities for any flows <br />transferred to the existing railroad ditch. . <br />49) Pleare expand the MiY/H Sedimentation Pond Retaining lY/all derign package to demanmate compliance with <br />C.A.S. 37-87-f05. <br />Response: Please refer to previous responses to Comments 11 and 29. <br />SO) Pkare have a regirtered engineer certify Drawing 2.03-M1 of the Permit Application Package (PAP) <br />Response: Please refer to previous response to Comment 32. <br />S f) A statement that all vegetation and organic materials rhal! be removed from the dirpara! ana and that the topsoil <br />shall be removed has been included in the application on page 2.0545; however, a ngirtered engineer har not certifted <br />thir page. Please include this rperifttation over rurh a certification (include in the engineering derign report). <br />ResnT_nse: A statement referencing the applicable construction specifications has been incorporated <br />into the ESC design report. Copies of the revised design information accompany these responses for <br />replacement in the Mining and Reclamation Plan document. <br />52) Pleare include ditch rpeciftcation in the rertifted engineering derign report <br />Response: Ditch designs were completed separately from the road and coal refuse facility designs <br />and the respective design packages were certified by the responsible design engineer, so it is not <br />appropriate or practical to include and certify [hese designs in the same package. Inclusion of ditch <br />specifications in either the road or coal refuse facility design package would also represent unnecessary <br />duplication. Cross-references to the ditch designs have, however, been added to the road and coal <br />refuse facility design packages and the corresponding permit text. Copies of the revised design <br />information accompany these responses for replacement in the Mining and Reclamation Plan <br />document. <br />53, 54, and 55J Although the application indicater on page 2.0545a that refure it to be plated and Compacted in <br />horizontal lftt, this page (rperificationf has not been included over the cert~cation of a registered engineer. Please <br />include this rpetification in the certifred engineering design report. <br />