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D. Letter, dated March 27, 2006, from the Colorado Division of Water Resources (Denver). <br />E Letter, dated March 29, 2006, from the Colorado Historical Society. <br />F Letter, dated April 13, 2006, from the Board of Delta County Commissioners. <br />G. Letter, dated May 1, 2006, from the Western Slope Environmental Resource Council. <br />H. E-mail, dated May 2, 2006, from Colorado Division of Water Resources (Denver). <br />L Letter, dated May 2, 2006, from the USDA-Forest Service. <br />J. Letter, dated May 2, 2006, from the Terror Ditch and Reservoir Company (with attachments). <br />K. Letter dated May 16, 2006 from Jason Ward of the Colorado Division of Water Resources <br />The Division has received two adequacy review letters as responses to BRL's submittal dated <br />December 28, 2006. Both letters are attached. <br />L. Letter dated February 22, 2007 from the USDA-Forest Service. <br />M. Letter dated June 4, 2007 from Jason Ward of the Colorado Division of Water Resources. <br />Division's Adeauaev Review Letter Dated June 6, 2006 <br />The proposed seismic monitoring plan is in Exhibit 18 of the revised materials. We believe the design, <br />metl, odology, hardware, and software are appropriate for the analysis required by the Division. While this <br />Exhibit discusses the technical aspects ofseismic monitoring, it does not clearly discuss the monitoring plan <br />with regard to timing, implementation, and reporting to the Division. Ultimately, some sort ofthreshold event <br />will need to be determined, and an a~talysis of how much ground motion is acceptable at Terror Creek <br />Reservoir without creating instability is also necessary. Additional stations relative to the mine plan maybe <br />necessary to confirm ground motion at or near the reservoir. The site-specific known seismic events being <br />presently collected from the current array should be used in any future analysis that is required by part 5 of <br />stipulation no. 9. <br />33. Included with the revised materials in Permit Revision 10 is volume 10, Geotechnical Studies, Bruce <br />Park Dam. One part of this l~olume is a report titled Geotechnical Evaluation of Mine-Induced <br />Seismicity on Bruce Park Dam, GEI Consultants, Inc, June 2002, Project 99292 (GEI report). This <br />report, and the analysis included, forms the basis for seven conclusions reached by GEI with regard <br />to mining within 1300 feet of Terror Creek Reservoir (Bruce Park Dam). <br />Conclusion 1 b states "The yield acceleration needs to be greater than the applied acceleration for <br />significant deformations to occur. " Figure 3.4 shows a yield acceleration much greater than the <br />average maximum acceleration at all depths. Therefore, it seems that significant deformations are <br />likely. Please clarify or correct this important conclusion as necessary. <br />11 <br />