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Bowie No. 2 Mine C 1996083 Technical Revision No. 84- Second Adequacy Review Page 6 of 15 <br />Reclamation Cost Estimate — Rule 2.05.4(2)(b) <br />43. a) The reclamation cost estimate for waste pile reclamation (cover and topsoil replacement) will be updated <br />under Technical Revision No. 77. As such, we will not propose to approve the revised cost estimate page <br />provided by BRL under TR -84. <br />b) Response accepted. BRL provided the requested volume. <br />The Division has prepared a reclamation cost estimate for TR -84 to update the cost of demolition of Gob Pile <br />#3 area structures (elimination of conveyor and refuse bin no longer proposed for construction, revised <br />culvert sizes, addition of culverts not in prior estimate) and the reclamation of the Pond J expansion that <br />results in a reduction in liability of $ <10,624.39 >. The estimate is attached. <br />New Items: <br />44. The second bullet in the Assumptions section of the 15 -Oct -2013 Buckhorn analysis states, "revised gob <br />properties were derived from recent laboratory testing on consolidated gob material by ATT Laboratories ". <br />Laboratory test results, particularly those upon which model assumptions are based, should be <br />incorporated into the appropriate geotechnical report(s), as was done by Buckhorn in 2006 and 2007. <br />a) Please expand the TR -84 (and any current or future) stability analysis to include the results of any <br />additional laboratory testing that has been conducted on coal mine waste at the Bowie No. 2 Mine. <br />b) For the native soil, an assumed 4 of 34 degrees was used. This value is not consistent with the 4 of 30 <br />degrees that was determined by Buckhorn in Mar -2007, based on laboratory testing of on -site <br />materials. Please provide justification for using a revised value for the angle of internal friction of <br />native soil, or revert to using the original value. <br />45. The third bullet in the Assumptions section of the 15 -Oct -2013 Buckhorn analysis refers to piezometers at <br />Gob Pile #3 that were monitored in June 2013 (no groundwater was observed). The Mar -2007 Buckhorn <br />report approved under TR -45 documents the installation of seven standpipe piezometers in the footprint <br />of Gob Pile #3. Based on readings taken in Nov -2007, a phreatic surface was developed for use in the <br />various stability analyses. <br />a) Please expand the discussion of the groundwater phreatic surface to address the condition of each of <br />the piezometers installed in 2007. Which of these piezometers have been disturbed or destroyed? <br />Which, if any, are still in use? What piezometers were utilized in 2013? <br />b) The current analysis fails to consider the effects (if any) of the sub - excavation of soil from the footprint <br />of the pile on the proximity of the phreatic surface. Please expand the analysis to consider Buckhorn's <br />original predicted location of the groundwater phreatic surface (based on the seven standpipe <br />piezometers) and the approved additional excavation of soil material from the footprint of the pile. <br />If you have any questions or need additional information, please contact me. <br />Sincerely, <br />al <br />Susan L. Burgmaier <br />Environmental Protection Specialist <br />cc: Tamme Bishop, J.E. Stover & Associates <br />Marcia Talvitie, DRMS <br />CIRCES Cost Estimating Soffi are <br />