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~. <br />r - <br />NORTHERN NO 1 HAUL ROR^ CUIV RTC <br />fiTIP11LRTION NO. 16 <br />In response to Stipulation No. 16 of the PROPOSED DECISION RND FINDINGS <br />OF COPIPLIRNCE dated October 19, 1964 the eight culverts at station <br />31+50 of the Northern No. 1 haul road is desSgned to pass the 10 year <br />24 hour event. <br />Rs per the attached calculations at a maximum head of 1.5 feet (as <br />actually measured by HanK Goufos) the eight 36 inch culverts will pass <br />357 cubic feet per second. In appendix R of the mine permit <br />application Espey, Huston 8 Rssociates, Inc. state that the peak flow <br />or worst case for the 10 year 24 hour event is 310 cfs. This 15 <br />assuming 0 di5ch arge from the sediment atfon pond. Therefore the <br />culverts have an excess capacity of 47 cfs or 15%. This !s well within <br />engineering tolerances. Even if the Northern No. I Sedimentation <br />Pond's gate valve is opened to allow continuous discharge with an <br />average retention time of 24 hours the peaK flow is Increased by only <br />0.14 cfs. <br />The peaK flow from the disturbed area again according to appendix A of <br />the Espey, Huston & Rssociates, Inc. report is 9.8 cfs. Rssuming after <br />reclamation that the sedircRntation pond is removed the peaK flow <br />through the eight culverts during a 10 year 24 hour event will be <br />approximately 320 cfs. The culverts still have an over cap icfty of 37 <br />cfs or 12%. This is still with in acceptable engineering tolerances. <br />I hereby certify that these calculations and statements are correct <br />within the confines of the accuracy of the data provided by Northern <br />Coal Company. <br />A. Troy Wills, P.E. <br />Dat~ ~ - <br />~~ ~ _ <br />"%4'r'~GtlAl ~~: <br />(. 4 _r~. <br />\ S, p <br />~' n<^~ <br />c <br />~' n.~ <br />_~ <br />`' <br />r <br />