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<br />EUGENE M. SHEARER,P.E. <br />CONSULTING GEOLOGIST <br />5720 South Jasmine Street <br />Englewood,CO 80111-1525 <br />(303) 771-2371 <br />13 July 1992 <br />Mr. Bryan Archer <br />Sun Coal Company <br />10200 West 44th Ave.,Suite 120 <br />Wheat Ridge, Colorado 80033 <br />Dear Bryan: <br />ReY: Explosive Sedimen- <br />tation Pond Emer- <br />~enc.v Spillway <br />Repair <br />Following the survey of the "as built" emergency spillway at <br />the Yampa Pond, 5 41ay 92. you requested that I conduct a <br />cursory inspection of the Explosive Sedimentation Pond to <br />determine if the spring freezing and thawing had caused any <br />problems to the pond function. The embankments, input <br />channel and primary dewatering device were in acceptable <br />condition, however, the emergency spillway was in a, <br />presumably weather induced, condition that made it <br />unacceptable for specifications set forth in Section <br />4.05.6(11)(e), Regulations of the Mined Land Reclamation <br />Board. <br />Although alternate repair suggestions were put forth, S1LRD <br />personnel indicated that the most time effective solution to <br />the problem focused on improvement of the existing emergency <br />spillway. This direction has proved to be most workable as <br />the program has progressed. <br />Inasmuch as remedial construction on the emergency spillway <br />proved to be a substantial undertaking, it seems appropriate <br />that an updated drawing of the "As Functioning" Explosive <br />Sedimentation Pond be available for submittal to the MLRD. <br />The original ".4s Functioning" diagram, dated 5 July 1990, is <br />at a scale of one inch equals ten Feet. Inorder to present <br />the new data in proper relationship to the existing file <br />information the accompanying map of the repaired emergency <br />spillway utilizes the same scale. If a larger scale drawing <br />of the repaired installation is required, one can be <br />provided on request. <br />The update of the 5 July 1990 "As Functioning" drawing <br />corrects a mismeasurement of length on the primary- dewater- <br />ing device. The trapezoidal channel for the spillway is <br />designed to be four feet wide, with 2h to lv sideslopes to <br />be lined with 0.5 riprap in a matrix of 0.1 gravel. A <br />maximum waterflow depth of 0.6 foot will adequately dewater <br /> <br />