Laserfiche WebLink
<br /> <br />(approximately 2,500 feet to the west) from Pond 11, <br />the postmining topography should have little affect, if <br />any, on these drainage structures, as well. <br />In conclusion, Seneca feels that during mining activity <br />and after completion of reclamation, that the existing <br />structures along Rockcastle Road should perform as well <br />as they are currently and not be compromised. <br />43a. The supporting calculations for weighted curve numbers <br />used in the culvert calculations has been included in <br />Attachment 13-8 as Table 13-8-1. <br />All designs and input data for every Road A and B <br />culvert were reviewed. All 16 culverts will be pipes <br />projecting from the fill. In Attachment 13-i, Addendum <br />2, the Dodson and Associates Hydraulics Program User's <br />Manual and Program Reference can be found. On Page 55 <br />of the manual, tables are included showing the entrance <br />loss coefficient for various types of culverts and <br />design of entrances. At the bottom of Table B-6, the <br />entrance loss coefficient for corrugated metal pipe, <br />projecting from fill (no headwall) is 0.80. Every <br />culvert was revised to show an entrance loss <br />coefficient of 0.80. This factor has very little <br />effect on the output if you review what is currently in <br />the permit and the revised material submitted in this <br />package. Also included for every culvert is the output <br />for the SEDCAD+ culvert sizing utility module. It <br />should be mentioned that in reviewing the inputs for <br />the SEDCAD+ program, that the entrance loss coefficient <br />utilized was 0.90. In looking at the help screen for <br />this input factor, SEDCAD+ suggests using 0.90 for a <br />corrugated metal pipe, projecting from fill. When <br />comparing the results of the Dodson and SEDCAD+ <br />programs, the same size culvert is generated by both <br />programs. Your statement that if SCC does not intend <br />to employ culvert inlets with headwalls and/or <br />wingwalls, the proposed diameter of Culverts YA-1, YA- <br />7, and YA-8 will not be adequate for the predicted <br />flows is incorrect. SEDCAD+ generated identical sizes <br />for these three culverts as the Dodson program did, and <br />no other input data was changed except for the entrance <br />loss coefficient. Finally, performance curves of <br />headwater versus discharge for each calculated culvert <br />and smaller and larger sizes has also been included <br />with this submittal. <br />For Culvert YA-6, designs for the 10-year and 25-year <br />storm event have been submitted. Someone else prepared <br />the initial and revised calculations for this culvert. <br />Please review and revised material with this submittal. <br />An answer for why the size has been reduced from two <br />72-inch culverts to two 60-inch culverts cannot be <br />4 <br />