1987-03-03_REPORT - M1977493 - Laserfiche WebLink

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.� The Urad mine produced about 14 million tons of ore and about 48 million lb of molybdenum metal. Two tail- `"` ings areas, covering about 125 acres, pose the major rec- lamation problem. Three major waste products are used "x' ► * f,� ?'';' £'. in reclaiming the tailings areas: 1) development-rock waste from the Henderson mine; 2) sewage sludge from Hydromulching a road cut at the Henderson project. Exten- Metropolitan Denver Sewage Disposal District No. 1, sine hydromulc•hing of road cuts and fills is being done along and 3) wood chips, a sawmill product of pole peeling, "Ith as much other revegetation as possible during construction from the Forest Products Division, Koppers Co., in Fra- ser, Co. The rock waste is hauled to Urad as it comes out of the shafts at Henderson. Seven trucks and a dozer were pur- chased for this project and the haul is continuing on a sev- en-day schedule. The rock stabilizes the tailings against wind and water erosion. It is placed at depths of three ft on the tailings surface, 15 ft on the lower halves of the w dam faces and 10 ft on the upper halves of the faces. The additional five ft on the lower halves is a drain blanket of graded rock, contiguous with each dam face, to ensure proper drainage of water should the phreatic line ever sur- face on the faces. Rock gradation is accomplished with the aid of adozer-mounted rock rake. " `: Development rock will stabilize Urad tailings Placing rock on the face of a tailings dam at Urad. The rock is placed at depths of 15 ft on the lo)rer half of the dam face and 10 About 1.5 million tons of development rock will be ft on the upper half to ensure proper rater drainage should the used to stabilize the Urad tailings. The rock then be- phreatic line ever surface on the faces comes the growth medium for vegetation on the tailings areas. Since the origin of the rock is 2,000 to 3,000 ft be- (Continued from page 43) developed and the cooperative effort is considered to have been very successful. However, some of the partici- pants do not feel the "experiment" could be repeated today. In 1967, the cooperation was voluntary. The ad- vent of NEPA in 1969 now requires a somewhat similar x approach. Since public exchange is required,the flexibili- ty and freedom which occurs during a voluntary ex- change of ideas has been partially lost. The Henderson mine has 30 years of proven and prob- able ore reserves. As with the Climax mine, comprehen- sive reclamation that far in the future is difficult to plan. Extensive hydromulching of road cuts and fills is being ,; done, along with as much other revegetation as is pos- sible in a high-density construction area. N Spreading hood chips. Observation of'the test plots indicated the most economical and beneficial soil amendments to be in Urad mine a short-term operation application of 20 tons per acre of both sewage and)rood chips Reclamation at the Urad mine poses an entirely differ- low ground, it is a very poor growth medium for plants. ent set of circumstances from the other two mines. Urad The major problem to be overcome is the lack of organic was a short-term operation. It closed in November 1974 matter and nitrogen. after seven years of production. Comprehensive reclama- Soil tests were performed and vegetation test plots es- tion of the Urad mine is therefore possible and is under- tablished to compare the rock and tailings as growth me- way. dia. A 4 x 4 factorial experimental design using various