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2. Provide an emergency spillway capable of passing runoff from the 25-year, 24-hour storm <br />event; <br />3. Provide adequate storage, in conjunction with Pond 016, for sediment generated as determined <br />by SEDCAD analysis; and, <br />4. Provide a nonclogging ciewatering device and principal spillway that will provide adequate <br />detention time for the 10-year, 24-hour storm event. <br />In some instances, mining will cause the drainage area to change during the life of the pond. When <br />mining into the watershed, the pit intercepts the runoff. In these cases a conservative pit move <br />procedure was used; the pond was analyzed for the largest anticipated disturbed drainage area that <br />will contribute runoff. It was estimated that this condition would occur if all of the proposed mining <br />area is disturbed and the area is in different phases of mining and reclamation. In addition, the <br />structure was conservatively designed to include adequate capacity for sediment storage and <br />retention of the ] 0-year, 24-hour storm event. Finally, the design assumed the principal spillway is <br />o en rable during the 25-year, 24-hour storm event and provides adequate freeboard to prevent <br />overtopping of the embankment. The SEDCAD output for the pond as-built conditions aze attached. <br />CONSTRUCTION SUMMARY <br />SCC personnel; Dan Allen (surveyor) and Roy Karo (Reclamation Manager) supervised the <br />construction of Pond 016A. Mr. AIlen and Mr. Karo ensured that all work was performed in <br />accordance with the design and specifications. In addition, MWH personnel (consultants) were on <br />site at several critical occasions during construction to conduct compaction testing, soil analysis, etc. <br />Suitable materials excavated from the pond area and associated side-slopes were used in the <br />embankment construction: The material was placed and compacted in the embankment to meet or <br />exceed the design specifications. <br />1, Robert J. Shevling (SCC Engineering Manager) inspected the embankment construction on a <br />frequent basis during construction and upon completion of the as-built to ensure proper construction <br />of Sedimentation Pond 016A and to satisfy the requirements of Rules 4.05.6 and 4.05.9. To the best <br />of my knowledge, based upon my professional expertise, and to the extent possible, Pond 016A was <br />constructed in accordance with prudent state-of--the-art methods for earthen embankment <br />construction. Further, the structure was constructed in compliance with the approved design, to the <br />extent possible, as specified in Attachment 13-SB of SCC's approved mine permit. Minor field <br />adjustments in horizontal and vertical alignments were necessary during construction to compensate <br />for unanticipated natural conditions, limit the disturbance area, and construct a structure consistent <br />with the reclaimed topography. To the best of my knowledge and belief, the field adjustments made <br />during construction are in conformance with the intent of the approved design plans and <br />specifications. . <br />TR-56 13-SF-F.2 Revised 09/06 <br />