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Temporary Conveyance Channels <br /> The Work Area Pond has two temporary conveyance ditches that route water from the <br /> disturbances areas around the Colowyo facilities area to the Work Area Pond. The locations of <br /> both ditches are presented on Map 12 and Figure Exh. 7-14WA-2. <br /> The assumed hydrologic condition for both temporary ditches is the post mine condition when <br /> the entire Work Area watershed is topsoiled, seeded, and reporting to the Work Area Pond. <br /> North and South Facilities Ditches <br /> The temporary North and South Facilities Ditches have been modeled under the 10-year, 24-hour <br /> storm event. Both ditches are trapezoidal in structure with a vegetative lining. <br /> A SEDCAD model has been included below which evaluates the peak flow and total runoff <br /> volume for both ditches for the 10 year, 24-hour storm event. The ditch configurations for the 10 <br /> year, 24 hour storm event for both temporary ditches are summarized on the table below. <br /> Facilities Ditches <br /> Peak Flow Average Channel Side MinimumErosion <br /> Station CFS Sloe % Type Slopes Depth Protection <br /> Feet <br /> South Facilities Trapezoidal 1H:1V <br /> Ditch 0+00 to 16.44 5.2 2' bottom 1H:7V 1.18 Vegetation <br /> 33+92 <br /> North Facilities <br /> Ditch 0+00 to 20.24 5.1 Trapezoidal 2H:1V 1.38 Vegetation <br /> 5+00 2' bottom <br /> North Facilities Trapezoidal 1H:1V <br /> Ditch 5+00 to 14.86 2.8 2' bottom 1H:7V 1.36 Vegetation <br /> 21+76 <br /> Exh. 7-20WA-2 Revision Date: 1/6/21 <br /> Revision No.: TR-146 <br />