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<br />as related to cover depth. The report also concludes that soil <br />sample results show little overall significant change over the 6 <br />year period, and references approved cover depths of 18" to 24" at <br />two other western Colorado Mines. On page 25 of the report, it is <br />stated that "it appears that a cover treatment of 24 to 36 inches <br />would support a self-sustaining permanent stand of vegetation and <br />the intended post-mining land use of wildlife habitat and grazing." <br />i would generally concur with the conclusions set forth in the <br />report. However, given the rather inconclusive nature of the <br />vegetation data due to generally poor establishment of seeded <br />vegetation, combined with the somewhat elevated SAR levels in some <br />of the lower soil zones, I would recommend a minimum replacement <br />depth of 36", rather than 24". The three foot replacement depth is <br />in line with literature recommendations for soil replacement over <br />sodic spoil referenced in our June 14, 1996 review letter. Also, <br />as noted in that letter, a review of soil type descriptions for <br />soils in the affected area which supported sagebrush/grass <br />vegetation prior to disturbance indicates that in general, the <br />soils associated with this vegetation type are good quality loams <br />and silt loams at least 30 inches thick. <br />I look forward to reviewing the final report, and associated <br />technical revision application. <br />Please contact me if you have any questions. <br />Since 1 , <br />~'/ ~ - <br />Dan T. Mathew <br />Environmental Protection Specialist <br />cc: Larry Routten <br />