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PROPOSED DECISION - Canadian Strip/Phase II Bond Release <br />October 1, 1990 <br />Page 2 <br />III, EVALUATION <br />On September 5, 1990, a Phase II Bond Release Inspection was performed at <br />the Canadian Strip Mine. Cathy Begej led the inspection, and it was <br />attended by Dennis Byrnes, OSM-Albuquerque, Dave Harr and Gene Dillashaw, <br />Kremmling Office of BLM, Glenn Murdock, previous employee at Canadian <br />Strip and Jerry Koblitz, Grey stone Development Consultants, the <br />permitting liaison for Wyoming Fuel Company. <br />The first condition which must be met for Phase II Bond Release concerns <br />erosional stability at a site, as defined by rule 3.03.1(3)(b). A site <br />should not contribute suspended solids to streamflow or runoff outside <br />the permit area in excess of pre-mining levels, as determined by baseline <br />data. Wyoming Fuel Company prepared a sediment loss analysis of the <br />sediment generated from a 10-year, 24-hour storm event using the software <br />package SEDCAD+, Version 3.0, and the Revised Universal Soil Loss <br />Equation (RUBLE) sub-routine, Vegetative cover information was derived <br />from baseline data from the reference areas and 1990 vegetation <br />sampling. The operator divided the reclaimed area into three watersheds, <br />coincident with the post-mining drainage and sediment Donds. The <br />analysis was run using three soil types: a composite of SCS sieve <br />analyses for soil types in the mine area; a composite texture from six <br />soil samples taken in upland areas of the reclaim and a composite texture <br />from two soil samples taken from sediment in the base of Ponds 1 and 2. <br />All runs in all watersheds showed lower sediment generation in the <br />post-mining situation, as summarized in Tables 1, 2 and 3 (attached). It <br />should be noted that these results reflect erosion protection provided by <br />both vegetative cover and total cover. At Canadian Strip, a wood chip <br />mulch was applied which still covers the site, <br />TABLE 1: Summary of SEDCAD+ <br />Results Using the SCS Particle Size Distribution in the Analysis <br /> Runoff Peak <br /> Mining Volume Discharge Sediment <br />Watershed Situation (ac-ft) fcfs) (tons) <br />1 Pre- 2.06 12,61 12.8 <br />1 Post- 1.90 15.26 3,3 <br />2 Pre- 1,08 8.78 5,3 <br />2 Post- 1,04 4.99 4,5 <br />3 Pre- 0.22 2.25 1.1 <br />3 Post- 0,05 0.45 0.1 <br />