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Letter to Jay Jones -5- November 29, 1995 <br /> later time, the Division will require a demonstration that the <br /> impoundments, in their present or future operating configuration, <br /> can safely contain and/or spill an appropriate inflow design flood. <br /> Determination of the magnitude of an appropriate inflow design flood <br /> would be partly based on whether an impoundment is designed to fully <br /> contain floodwaters, or whether an impoundment is designed to pass <br /> all or part of the floodwaters through a spillway or spillways. The <br /> evaluation of the impoundments ability to handle the inflow design <br /> flood must be based on initial conditions that consider maximum <br /> operational water volumes, and the freeboards associated with <br /> maximum operational water volumes would become an enforceable <br /> component of the Reclamation Permit. If the impoundments are <br /> designed to spill any portion of the inflow design flood outside the <br /> containment of the Climax water treatment and discharge system, a <br /> statement that such releases are permissible under the Climax CDPS <br /> Permit will be required. <br /> (c) In Exhibit G of the Climax Mine 1989 permit amendment, it is <br /> stated that the Robinson Lake spillway is deigned to pass the <br /> probable maximum flood. It is further stated that when Robinson <br /> Lake reaches storage capacity for any reason, overflow is pumped to <br /> the Tenmile drainage for treatment and ultimate discharge. Section <br /> 5.4 .2 of the EPP indicates that after Eagle Park Reservoir is <br /> converted to fresh water storage, it will still retain the long-term <br /> emergency function of containing accidental and unanticipated <br /> releases from the Robinson Reservoir and other upstream sources. <br /> Won't the Eagle Park Reservoir be classified by the Water Quality <br /> Control Division once conversion to fresh water storage is complete? <br /> Also, please provide information on minimum operational freeboard in <br /> Robinson Lake, and relate the storage capacity associated with the <br /> freeboard to a frequency analysis of storm related inflows. It is <br /> the Division's view that in accordance with Rule 6.4. 19 (7) (f) , <br /> minimum freeboard should become an enforceable permit requirement, <br /> and that discharge from the emergency spillway to Eagle Park <br /> Reservoir should only occur in the event of a relatively extreme <br /> storm event. <br /> (d) Water pathways between the Mayflower decant system, the <br /> concrete collection ponds below No. 5 Dam, the Mayflower impoundment <br /> under-drains, and the clear water pond need to be better described <br /> and illustrated. I have not been able to obtain a good <br /> understanding of these relationships from the EPP narrative, <br /> schematics, or maps. Also, what is the minimum operational <br /> freeboard for the clear water pond? Minimum freeboard may have to <br /> be specified as a permit condition to provide sufficient storage <br /> capacity for unusual storm water inflows as well as seep water <br /> inflows during possible pump-back system down-time. <br /> (e) In Exhibit G of the 1989 Climax Mine permit amendment, it is <br /> stated that: <br />