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. MAGPIE CREEK DIVERSIQN <br />The Magpie Creek temporary diversion is designed to divert Magpie Creek <br />around the surface facilities area. Its location is shown on the <br />Drainage and Sediment Control Map, (Map 20). The diversion is designed <br />and constructed to safely pass the 10-year, 24-hour storm event. <br />An as-built longitudinal profile and plan view drawing, prepared by <br />Western Engineers. Inc. has been reproduced as the Magpie Creek <br />Diversion As-Built Drawing, (Map 25). The drawing illustrates the <br />diversion's present configuration. The diversion begins at Station G, <br />approximately 400 feet east of County Road 92, and extends for <br />approximately 1.750 linear feet. The upper reach of the diversion has <br />a trapezoidal configuration with a 14-foot average bottom width, 2.5H:V <br />sideslopes and an average 1.1 percent channel slope. Starting at <br />Station 0, the lower reach is also trapezoidal with a 16-foot average <br />bottom width, 2H:1V sideslopes and an average 8 percent channel slope. <br />• The Magpie Creek drainage basin is located in a ponderosa pine-pinyon- <br />juniper woodland zone located between a ponderosa pine-douglas fir zone <br />in the foothills to the west and the short grass prairie to the east. <br />Two (2) major vegetation types are found in the drainage basin: <br />grassland and ponderosa pine-pinyon-juniper woodland. <br />For design purposes, the Magpie Creek drainage basin was divided into <br />two (2) subwatersheds. The upper reach of the diversion is designed to <br />pass the flow from the upper subwatershed and the lower reach is <br />designed to pass the flow from both subwatersheds. The lower <br />subwatershed flows into the Magpie Creek diversion at Station N as <br />shown on the Magpie Creek Diversion As-Built Drawing, (Map 25). <br />The peak discharge from the 10-year, 24-hour storm event was used to <br />confirm the stability of the existing Magpie Creek temporary diversion. <br />The maximum flow velocity int the upper channel reach from Station G <br />to Station 0 is 5.3 fps. Starting at Station 0, the channel steepens <br />for the last 400 feet before reaching the existing 8.8 feet diameter <br />• culvert under the GEC mine access road. The upper section has a well <br />138 Revised 7/24/01 <br />Technical Revision No. 32 <br />