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., <br />POWDERHORN COAL COMPANY <br />NORTH DECLINE CHANNEL <br />CERTIFICATION <br />Updated 7/25/01 <br />The North Decline permanent channel relocation was performed in the spring of 1992 as <br />part of the final reclamation of the North Decline site. Larry M. Reschke, P.E., certified the <br />construction of the channel relocation in 1995. Mr. Reschke certified the permanent <br />channel relocation meets or exceeds the design requirements of plans submitted to and <br />approved by the DMG. <br />During 2000, UTE Water replaced most of its aging 24-inch water line with a new 48-inch <br />welded steel pipeline. This new water line crossed the reclaimed North Decline and cut <br />through the upper (southern) end of the engineered North Decline channel. <br />The North Decline channel is shown in plan view on Exhibit 12C and in section view on <br />Exhibit 21. The section of the channel that was disturbed and reconstructed is <br />represented by Section B-C on Exhibit 21. Section B-C on Exhibit 21 shows a trapezoidal <br />channel 35-feet wide at the bottom, 2-feet deep with 2H:1 V side slopes, a 2.5% grade and <br />requires 6-inch rip rap (Dso = 6"}. <br />UTE Water reconstructed the North Decline channel during November 2000. Although <br />UTE only disturbed approximately 50-feet of the channel, they constructed approximately <br />325-feet of new channel. This extension of the channel to the south provides a good <br />transition from the natural ephemeral channel to the engineered riprap channel. The new <br />channel segment has a fairly consistent grade which averages 3.2%. <br />Section B-C on Exhibit 21 presents the best representation of the reconstructed channel. <br />The design of Section B-C is based on a 2.5% grade whereas the reconstructed channel <br />has a fairly consistent grade which averages 3.2%. The following table illustrates the <br />insignificant difference between the design 2.5% grade and the as-built 3.2% grade. <br />Grade Flow Depth Velocity D50 Riprap <br />2.5% 1.5 8.3 4.1" <br />3.2% 1.3 8.6 4.8" <br />I James E. Stover have inspected and surveyed the reconstructed channel. Based on the <br />above table and to the best of my knowledge and belief, the reconstructed channel meets <br />the applicable p~o~f8tistandards and design criteria presented in Powderhorn's <br />Mining and R~1@~e~+or~,~~it, C-81-041. <br />~ z:v . <br />• <br />E. Stov,Q~~ <br />do Prpfi'~ional Engineer <br />~C>~ 19230 <br />ZS n l <br />Date <br />