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1 <br /> and small earthen channel spillways serve as the primary spillways for each pond. Area- <br /> Capacity tables for each pond are presented on Figure 2 as well as included in the tables in the <br /> SEDCAD output. . Each pond is assumed to be full to the primary spillway elevation at the start <br /> of the 10/24 and 25/24 events. Spillway details and the stage storage curve are presented on <br /> the original design drawings. <br /> The runoff inflow into each pond is then routed through the pond to determine the peak pool <br /> elevation while passing the storms. Because the ponds are in series, the inflow into the East <br /> Pyeatt Pond 1 pond includes the runoff from its direct watershed plus the routed outflow from <br /> the haulroad crossing. Similarly, the inflow to the lowermost ponds includes the routed outflow <br /> from both upper ponds plus the runoff from their directly tributary watershed. <br /> As shown in the SEDCAD output, the 24-hour average settleable solids concentration released <br /> from the lowermost pond ( East Pyeatt Pond 3), is 0.00 ml/l, well below the 0.5 ml/I settleable <br /> solids standard. <br /> In the 25/24 event, the ponds spillways flow at depths of 2.35 feet, 1.51 feet, and 1.82 feet <br /> below the lowest spillway elevation in the East Pyeatt Pond 1, East Pyeatt Pond 2 and East <br /> Pyeatt Pond 3, respectively, leaving freeboard to the dam crest of 4.65 feet, 2.5 feet, and 5.2 <br /> feet respectively. In conclusion, the existing pond structures are sufficient to adequately treat <br /> the additional planned disturbance. <br /> The following materials accompany this submittal: <br /> • Figure 1, "East Pyeatt Area As-Built Ponds" <br /> • Figure 2, "East Pyeatt Area As-Built Ponds, Year 2019" <br /> ENGINEERING CERTIFICATION <br /> I am a Registered Professional Engineer in the State of Colorado and a representative of <br /> Environmental Solutions, Inc, P. O. Box 2996, Cheyenne, Wyoming. Being familiar with the <br /> Trapper Mine operation and the coal program permitting process in Colorado, to the best of my <br /> knowledge and experience the attached document meets the requirements of current <br /> regulations and the applicable requirements of the approved permit document within CDRMS <br /> Permit C-1981-010. <br /> ♦`����Pq 0 L �C i�i4 <br /> i <br /> ' 32257 z <br /> Ce <br /> O <br /> z (ns. '••....••�GEC♦♦� <br /> THOMAS C PETERSON <br /> P.E. No.32257 <br /> �L4//a <br /> " VAIL <br /> 2 August, 2018 <br />