1985-11-25_ENFORCEMENT - M1977378 (2)

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Mill Tailings Revegetation Project Page 2 ated at the 1000 tpd level from 1960 to 1978, when it closed due to inundation of the mill ore source by a glacial tarn located above the mine. The Mayflower tailings disposal system was used by Standard Metals on tailings pond No. 2 until 1974 and on pond No. 1 until 1975. In 1976 an entirely new tailings disposal site and system were con- structed, and the old ponds abandoned. The new disposal system em- ploys an underground pipeline for transporation and a cyclone for coarse-fine particle separation. The new tailings disposal system was a significant improvement because it eliminated tailings slurry spills which frequently occurred using the launder system; thus the amount of land area impacted by tailing pond construction decreased. Also, use of the cyclone for separation of tailings particles enabled better size class separation to be achieved, ultimately resulting in construction of a much more stable pond impoundment. Project Background In June 1975 the southwest berm of tailings pond No. 1 failed, re- leasing a portion of the pond' s interior to adjacent water courses. Regulatory agency action which resulted from the tailings spill re- quired Standard Metals to formulate and implement a stabilization program on inactive tailings deposition areas to reduce the potential of future breaks. Passage of the Colorado Mined Land Reclamation Act the following year (1976) made reclamation of all lands disturbed by mining activities in Colorado mandatory. In compliance with regulatory agency stipulations and the enacted reclamation legislation, Standard Metals personnel developed a reclamation plan for affected lands at the Silverton site in 1976 and initiated the plan in June 1977. Revegetation to a forest habitat was selected as the stabilization and reclamation plan for tailings ponds and other disturbed sites upon consideration of economical , physical and aesthetic factors. The goal of the revegetation program is to establish a self-sustaining vegetative cover reflecting species composition and density of adjacent floral communities. It was determined that establishment of a persistent vegetative cover on tailings depositional sites as well as other affected lands would satisfy physical stability requirements for steep tailings slopes and also mitigate pollutional impacts of these disturbed lands by wind and water erosion. In order to achieve the revegetation goal , the program was divided into three phases. 1. Seed bed stabilization 2. Pioneer community establishment 3. Secondary or successional community establishment. The initial phase, seed bed stabilization, is devoted toward modification of the seed bed microclimate to enhance seed germination and seedling survival . This objective is accomplished by: (1) erection of snowfences on tailings areas perpendicular to prevailing wind direction to decrease wind velocities across the seedbed, which prevents the seed from becoming