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CommenUResponses, TR$2 <br />Page 3 <br />to continue through at least 2012, and reclamation operations will continue for some time <br />beyond that. Soil replacement thickness should reflect the best estimate of available soil <br />volume to be salvaged from azeas yet to be disturbed, in conjunction with the current <br />volume of soil in stockpile. In addition to the "current" topsoil balance provided in <br />proposed Table 2.05-1, updated versions of the soil balance projections provided in <br />current Tables 2.05-1 and 2.05-2 should also be provided. <br />Please provide new topsoil balance projection tables for the remainder of the mine <br />fife, comparable to current Tables 2.05-1 and 2.05-2. Projections should incorporate <br />salvage volumes estimated for remaining areas to be disturbed, based on acreage <br />and projected salvage thickness for the affected soil types. If experience has shown <br />that original salvage volumes were over-estimated, it may be reasonable to base <br />salvage projections on the low end of the thickness range listed for the deeper soil <br />types, rather than the mid-point. For example, salvage projection of 30" rather <br />than 40" for Barnette soils, 25" rather than 35" for Work soils, and 20" rather than <br />25" for Havre soils. <br />Response: Given the mature phase of mining for the current permit, the remaining topsoil <br />stripping has a relatively limited impact on the overall replacement depth. As stated in <br />the comment to Item 2, only a limited amount of stripping remains. <br />One of the problems with the original soil mapping is the lack of detail in using this data <br />to predict topsoil stripping volumes. The attached Figure 1 diagram is provided to <br />illustrate this. As shown, there were two areas stripped in 2005 totaling about 78 acres. <br />The topsoil polygon data shown was obtained from Map 6. While the system of mapping <br />unit numbers has been modified based on updated soil nomenclature, the topsoil <br />polygons themselves are unchanged from the original soil mapping provided on Map 6. <br />This data is believed to be based on an Order 3 Soil survey. <br />Note that only three soil polygons are significantly represented by the 2005 stripping <br />areas. These are: <br />Map Unit Old Map Unit <br />135 (formerly 17E) <br />37 (formedy 14E and 14F) <br />206 (formerly 104) <br />Soil Name Depth Range <br />Work Loam 25" - 45" <br />Burnett 30" - 50+" <br />Borolls Rock Outcrop 0" - 8" <br />Actual field conditions encountered during topsoil stripping activities tend to be much <br />more variable that the general mapping units presented on Map 6. Thus, its value as a <br />planning tool is limited. <br />4. For verification purposes, and to provide early indication of the need for any future <br />adjustments in average topsoil replacement depths, please provide a permit <br />commitment to submit survey-based annual topsoil balance documentation (as <br />provided in amended Table 2.05-1), within each year's Annual Reclamation Report. <br />Response: We agree that this is a reasonable request. A commitment to provide an annual <br />analysis of available topsoil quantities will be presented in each year's Annual Report. A <br />