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,~. ~-8 sl~~ ~>cti . s.s' III IIIIIIIIIIIIIiII ~dyP .o~-~ • Project Name: Power Borehole Access Culvert PD-1 Prepared by: DJK Date: 3/27/00 Project Number: 1342845.06180100 Checked by: %!=G Date: ~~L/b~ Purpose: Montgomery Watson has been asked by Twentymile Coal Company (TCC) to design a culvert for the access road to the Power Borehole site. The purpose of the culvert is to prevent any water from ponding along side the road. Methodology: A culvert (PD-I) will be installed under the borehole access road prior to the road entering the pad area. The watershed contributing to the culvert is small in size (0.45 ac) and consists primarily of the light-use road. The entire watershed was assumed to be disturbed for purposes of this culvert design. The 10-year, 24-hour storm was used in this design which is appropriate for this application. Hydrology was modeled using the SEDCAD4 computer model consistent with methodologies presented in previous submittals. Hydrology results are presented on the accompanying SEDCAD4 computer printouts. The inlet control nomograph for corrugated metal pipes (cmp) developed by the Bureau of Roads in 1963 was used for culvert design. This nomograph is recommended in the National Engineers Handbook, Section 4, Hydrology (1972) and has been used in previous TCC submittals. The culvert was designed with a projecting entrance and a HW/D = 1. Desien Parameters Hydrology Storm Event Area • Curve Number Land Use Peak Flow Culvert Design IO-year, 24-hour - I.R in. 0.45 ac 90 Assume all disturbed 0.44 cfs Culvert Size = 12" Refer to attached nomograph. National Engineers Handbook, Section 4, Hydrology (1972), Exhibit 14-9. CERTIFICATION 1, DANIEL KEUSCHER, STATE THAT THE INFORMATION P THROUGH DF-8 WAS PREPARED BY ME AND IS CORRECT KNOWLEDGF. AND INFORMATION. ~30 2006 DATE DANIEL iE GES DP-1 Y • ....,~ '~~ ~i:° r~+. '° 33307 ~' ~• •~ Si,12•~~ 33307 ~OMAI ~ APPROVED JUN 1 4 2000 ~"