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Reservoir Spillways and Dewatering <br />Each of the four large sediment ponds has been equipped with an emergency and <br />principal spillway. The principal spillway will allow dewatering though a drop <br />inlet, or riser pipe, which will be perforated. A skimming device consisting <br />of half a CMP section will be installed over the perforation to prevent the <br />discharge of floating oil and grease. Until impounded water accumulates to the <br />perforation level and can be discharged, it will evaporate or percolate through <br />the reservoir sides and bottom until sediment acts as a liner. In anticipation <br />of no flow through the riser pipe, the applicant intends to obtain water stor- <br />age rights (p. V-9). <br />Sediment Removal <br />Sediment storage volumes were developed based on three year yields calculated <br />by using the Universal Soil Loss Equation. These were derived by examining the <br />characteristics of the upstream drainage area contributing to the sediment <br />pond, including disturbed and undisturbed areas. Tons of sediment contribution <br />per year was established for each subarea and then tripled to obtain the re- <br />quired sediment storage volume. Sediment will be removed from each pond when <br />it has accumulated to 60 percent of the design capacity. The sediment will <br />then be disposed of in the Refuse Disposal area (page IV-74). <br />Monitoring _ 7 <br />Surface water quantity and quality will be monitored at the same stations that <br />were used for collection of baseline data. These nine stations include two <br />sites each on the White River, Scullion Gulch and Red Wash, and one at Raven <br />Park Dam, Lincoln Reservoir and Fossil Reservoir in the headwaters of Scullion <br />Gulch (Figure 11 .C-11):~ Additionally, data collected by the U.S. Geological <br />Survey at station no. 09206300 on the White River above Rangely will be <br />examined and utilized. Monitoring points have been proposed at the outlet of <br />the four sediment ponds in the D-Portal and Refuse Disposal Areas. These <br />discharges will 6e monitored in accordance with the NPDES permit for which the <br />applicant has applied. <br />9 <br />