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3.4. However, a more detailed description of the area weighting procedure and statistics for use <br />in comparison of reference area data to reclaimed area data will need to be provided. The aced <br />for such clarification is due in part to the complexities associated with the establishment and <br />documentation of the reference areas originally, in 1 991 and 1 992, The CCA report makes <br />reference to x`50150" weighting for the two sagebrush reference areas ( SREF-A and SRF -, <br />established in 1991 and 1992 respectively), but supporting rationale would need to he provided. <br />The major portion of the disturbance is in Mine Area 1, which is associated with S EF- , the <br />southern sagebrush reference area, established in 1991. Both sagebrush reference areas were <br />used for comparison to the much smaller Mine Area 3 disturbance, in 1992. As such, it would <br />seem that SREF-A would logically be weighted more heavily than SREF- (since all of the <br />sagebrush acreage that originally occurred within the disturbed portion of Mine Area 1, and <br />half of the sagebrush acreage that originally occurred within the disturbed portion of Mine Area <br />3, would be represented by SREF --A ). SREF -A was apparently the more productive of the two <br />sagebrush reference areas when both were sampled in 1992. <br />Please consider this matter and provide detail and justification for the area weighting <br />procedure within a minor revision application addressing Phase IiIII revgetatin <br />sampling plans and revgetatin success demonstration approaches, prior to submittal of <br />the next Phase II or Phase III bond release application. Area weighting should reflect the <br />percentage of the reclaimed area to be represented by the split Grassland Reference Area, <br />SRF-, and SREF-B, based on percentage of the disturbance that was originally <br />Grassland, percentage that was originally Sagebrush represented by only SRF-, and <br />percentage that was originally Sagebrush represented equally by SR F-A and SR F- . <br />Any reclaimed acreage that was originally Pinyon- Juniper would need to be allocated to <br />one or both of the Sagebrush reference areas, with justification. <br />3. The SL-02 application does not provide narrative or documentation addressing topsoil <br />replacement in conformance with permit requirements. Figure 1 of the SL-02 application <br />indicates an average soil replacement thickness of 10.7 inches was applicable for Mining Area <br />1, and a 16.4" replacement thickness was applicable for Mining Area No. 3 and associated <br />ancillary sites. <br />Please provide sample based documentation of soil replacement in conformance with <br />applicable criteria, in the context of any future Phase II bond release application. If such <br />data has not been previously collected, the Division requests that soil thickness sampling <br />be conducted on a 5 acre grid, with results to be included in the Phase II release <br />application. <br />4. It appears that the minimum liability period for Phase III bond release has been met, and the <br />operator may want to consider implementing data collection for Phase III as well as phase II, <br />for the entire reclaimed area in the near future. Vegetation cover data from the initial year of <br />sampling could be used for a Phase II release request, if desired. <br />