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., <br />change of a mere 2 feet is sufficient to trigger extraordinary <br />concern and subsequent expedited measures by Colowyo appears to be <br />unfounded and overly conservative. <br />However, Colowyo recognizes the Division's concern for a triggering <br />mechanism to be in place whereby the Division would be notified in <br />the highly unlikely event that a significant water level were to <br />develop in the fill. The question is what triggering mechanism is <br />satisfactory to address the Division's concerns while at the same <br />time not being overly conservative. <br />Colowyo proposes that, recognizing the stability analyses conducted <br />by CTL/Thompson indicates the fill would be stable even with a 100 <br />foot water table above bedrock, the mechanism for Division <br />notification could be at some percentage of that figure. Colowyo's <br />proposal ie for the Division notification to occur at 108 of the <br />maximum water table or 10 feet of water above bedrock. At this time <br />Colowyo will contact the Division within two working days and <br />complete a survey of the twelve subsidence monuments and report the <br />results to the Division within one month. The revised permit page <br />4.09-2 with these commitments is attached for your review. <br />The Division might also recall that other stipulations regarding <br />preparation of detailed engineering plane to abate any imminent or <br />manifested elope stability problems remain in effect.(Permit page <br />2.06-2) Colowyo believes that the combination of these original <br />requirements plus the new requirement for Division notification will <br />provide the detail necessary to insure that the Streeter fill <br />remains a stable, excellent example of western reclamation. <br />Sediment Pond Surveys: <br />Ae recommended by the Division, Colowyo will commit to conducting <br />sediment surveys on the Gulch A pond (discharge point 004) on a bi- <br />annual basis rather than every third year as proposed. The revised <br />permit page 4.05-6 reflecting this change is attached for the <br />Division's records. Colowyo anticipates that once reclamation <br />progresses to a significant degree at the top of the reconstructed <br />Gulch A drainage this issue will be revisited and the frequency of <br />survey modified further. <br />Overburden Honitoring - In Pit <br />Colowyo'e remaining overburden monitoring requirement will consist <br />only of the current regraded overburden monitoring program. <br />Sincerely, <br />~~~~ ~ ~o~ <br />amee A. Kiger J <br />Sr. Environmental Specialist <br />xc: R. G. Atkinson <br />Central Files <br />c:~wnivu:~rx:e <br />