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• Appendix M(i) <br />72-Inch Culvert <br />The Munger Canyon Mine haul road has one 72-inch diameter culvert which conveys <br />the Munger Creek flow under the haul road. The location of the culvert is shown on <br />Figure 2.3-4 Surface Hydrology Map. <br />Rule 4.03.1(4)(e)(i) states that culverts with an end area of 35 square feet or less shall <br />be designed to safely pass the 10-year, 24 hour precipitation event without a head <br />unless suitable protection against erosion or fill saturation is in place at the entrance <br />and exit of the culvert. <br />The end area of the 72-inch diameter culvert is less than 35 square feet, therefore it <br />must be designed to safely pass the 10-year, 24 hour event. The calculations of flow <br />for Qto, 249 cfs, are located in Appendix M(v). <br />A 72-inch diameter culvert will safely pass 249 cfs with a HW/D ratio of approximately <br />1.3 according to the nomograph, Figure 4-28, on page i 89 of the Handbook of Steel <br />Drainage & Highway Construction Products, AISI 1983. <br />In my opinion, the existing 72-inch diameter culvert has suitable protection against <br />• erosion and fill saturation at the entrance and exit of the culvert. This opinion is based <br />on my inspection of the culvert and the fact the culvert has been in place for over 20- <br />years. Therefore, the existing 72-inch diameter culvert meets the requirements of Rule <br />4.03.1(4)(e)(i). <br />ENGINEER'S CERTIFICATION <br />The calculations and information presented on this page were prepared by me during <br />the month of August 2003, and the information presented is true and correct to the <br />best of my knowledg~,ig~id~S,~ief. <br />a ~ 03 <br />,~P.E. Date <br />i~al Engineer <br />~o. 19230 <br /> <br />M" <br />Page 15 <br />New 08/03 <br />