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Geotechnical Evaluation ofMine-Induced Seismicity on Bruce Park Dam <br />On page five, in Section 2.4 -Basis for Selecting Ground Motion Time History, the <br />report states that a modified earthquake record was used in the seismic analysis of <br />the stability of the dam. In our discussion, you said that this was not a problem. <br />However, Greg Hunt of Bowie Resources told me that the National Institute of <br />Occupational Safety and Health (NIOSH) had been gathering Feld data concerning <br />rockfall seismicity but was not fmished writing the report. Would it be of value to <br />contact NIOSH and see if they have asite-specific roof fall seismic signal that could <br />be compazed with the modified earthquake seismic signal that was used in the <br />operator's report? Kent also had concerns about the use of earthquake data in the <br />analyses. <br />4. On page twenty, in Section 5 -Conclusions, statement number six states that the <br />consultant believes that no significant threat to the dam, reservoir or landslide is <br />expected. Considering that the reservoir's main embanlanent is a Class I dam, should <br />we ask the consultant what they mean by "significant"? <br />General Questions <br />The Division and the Division of Water Resources assumed that mining the D seam <br />up to within one mile of the Bruce Pazk Dam was acceptable and would not require a <br />demonstration of the geotechnical stability of the dam. BRL has mined up to the one <br />mile limit and has stated informally that they do not intend to mine the D seam any <br />closer to the Bruce Park Dam than that. Do the geotechnical reports submitted by <br />BRL demonstrate that the Divisions' acceptability of the one mile limit for the D <br />seam mine plan was a correct assumption? <br />6. BRL is preparing to submit a new mine plan for the Bowie No. 2 Mine, in which the <br />B seam would be mined. Apparently, the mine plan submittal will not include mining <br />to within less than one mile of the Bruce Pazk Dam. Similaz to the D seam question <br />above, do the reports demonstrate that the acceptability of the one mile limit for the <br />B seam is a correct assumption? <br />7. If BRL decides to mine the B seam closer than to within one mile of the Bruce Park <br />Dam, aze the current seismic analyses regazding the D seam applicable to the B seam <br />or will BRL have to submit new analyses? <br />cc: Sandy Brown <br />Dan Hernandez <br />Kent Gorham <br />