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<br />_11_ <br />~~ <br />Information in the original permit application on the quantity and quality of <br />surface water in the mine area can be found on page 2.04-8 and Exhibits 6 and <br />8 of Volume 1, Exhibit 9 of Volume 2, and maps 8 and 9 of Volume 3, and in <br />CF&I's October 12, 1982 response to the Division's Draft Findings. <br />The hydrologic balance of the proposed refuse disposal site will be protected <br />by the placement of a sediment pond downstream of the refuse embankment which <br />will collect all water draining over and through the pile. <br />The Division has reviewed the proposed sediment pond for compliance with the <br />regulations regarding sediment storage and design storm retention. Due to the <br />large nature of the proposed embankment, the Federal Mine Safety and Health <br />Administration (MSHA) will be reviewing the structure for stability and hazard <br />considerations. Because the MSHA review will not be completed until after <br />this decision is issued, the following stipulation is necessary. <br />STIPULATION N0. 1 <br />PRIOR TO ANY CONSTRUCTION ACTIVITIES FOR THE PROPOSED SEDIMENT POND, WYOMING <br />FUEL COMPANY MUST RECEIVE A WRITTEN NOTICE TO PROCEED FROM THE DIVISION. THIS <br />NOTICE WILL BE PROVIDED ON THE BASIS OF MSHA APPPROVAL OF THE STRUCTURE AND <br />THE DIVISION'S REVIEW OF ALL MATERIALS SUBMITTED TO SECURE MSHA APPROVAL. ALL <br />MATERIALS SUBMITTED TO MSHA FOR REVIEW SHALL ALSO BE SUBMITTED TO THE DIVISION, <br />Due to the long life of active placement of refuse in the pile and the <br />relatively large drainage area (85.1 acres), the sediment pond will be a <br />constructed embankment with a height of 35 feet. In order to insure stability <br />of the embankment, and to insure that the pond only delays water and does not <br />store it, two dewatering devices have been designed: the first (at the 2 acre <br />foot level) will be effective during the early years of refuse placement when <br />total sediment yields will be less than the total design life. The first <br />dewatering device will be closed at such time that stipulated sediment volume <br />has been filled. At this time the second dewatering device (at the 4.95 acre <br />foot level) will be opened and be the effective dewatering device for the <br />remaining life of the embankment. The following stipulation is required in <br />order to ensure effective operation and stability of the sediment pond. <br />STIPULATION N0. 2 <br />THE OPERATOR MUST COMMIT TO THE FOLLOWING MAINTENANCE OF THE SEDIMENT POND: <br />A. ONLY ONE DEWATERING ORIFICE WILL BE OPEN AT A TIME. THE FIRST ORIFICE <br />AT THE 2 ACRE FOOT LEVEL WILL 8E CLOSED AT SUCH TIME THAT THE SEDIMENT <br />VOLUME REACHES 60% OF THE DESIGN STORAGE OR 1.2 ACRE FEET. AFTER <br />CLOSURE OF THE FIRST ORIFICE, THE SEDIMENT LEVEL WILL BE MAINTAINED AT <br />NO MORE THAT 40% OF THE 4,95 ACRE FOOT DESIGN VOLUME FOR SEDIMENT OR AT <br />APPROXIMATELY THE 2.0 ACRE FOOT LEVEL. STAFF GAGES WILL BE INSTALLED TO <br />ASSURE PROPER DETERMINATION OF SEDIMENT LEVEL. <br />6. THE OPERATOR WILL MAKE QUARTERLY INSPECTIONS OF THE SEDIMENT POND IN <br />ORDER TO ASSURE THE OPERABILITY OF THE DISCHARGE STRUCTURES AND <br />STABILITY OF THE EMBANKMENT. <br />