2008-08-01_REVISION - C1996083 (3)

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reasonably approximates a seismic signal generated from longwall mining at the Bowie No. 2 Mine. Please provide such a demonstration. The Division has no further concerns. In the May 12, 2008 submittal, BRL added an appropriate discussion to Exhibit 18. B. In the TR-22 review, the Division received a letter from the Colorado Division of Water Resources (DWR), dated June 11, 2003, in which additional information was requested concerning the landslide immediately adjacent to the Bruce Park main dam. A copy of this letter is attached. Please submit these data and report, per the recommendations described in the DWR letter of June 11, 2003, as part ofthe adequacy review for PR-10. The Division has no further concerns. The May 12, 2008 submittal contained a geotechnical monitoring plan in Exhibit 20 of Volume IIIA. 32. The Division has received one comment letter from the USDA-Forest Service, dated April 18, 2008, which is attached. The Division anticipates receiving a comment letter from the Colorado Division of Water Resources, which will be forwarded to BRL when it is received. In a response dated April 18, 2008 and sent to BRL in the Division's adequacy review letter dated June 12, 2008, the USDA-Forest Service stated that BRL's responses to their concerns are adequate and that, provided the PR-10 application is not further modified, they concur with the approval of PR-10. The Division has not received the latest comment letter from the Colorado Division of Water Resources yet but will forward it to BRL when it is received. Division's Adeauacv Review Letter Dated June 6 2006 The proposed seismic monitoring plan is in Exhibit 18 of the revised materials. We believe the design, methodology, hardware, and software are appropriate for the analysis required by the Division. While this Exhibit discusses the technical aspects of seismic monitoring, it does not clearly discuss the monitoring plan with regard to timing, implementation, and reporting to the Division. Ultimately, some sort of threshold event will need to be determined, and an analysis of how much ground motion is acceptable at Terror Creek Reservoir without creating instability is also necessary. Additional stations relative to the mine plan may be necessary to confirm ground motion at or near the reservoir. The site- specific known seismic events being presently collected from the current array should be used in any fixture analysis that is required by part S ofstipulation no. 9. 33. Included with the revised materials in Permit Revision 10 is Volume 10, Geotechnical Studies, Bruce Park Dam. One part of this Volume is a report titled Geotechnical Evaluation of Mine- Induced Seismicity on Bruce Park Dam, GEI Consultants, Inc, June 2002, Project 99292 (GEI report). This report, and the analysis included, forms the basis for seven conclusions reached by GEI with regard to mining within 1300 feet of Terror Creek Reservoir (Bruce Park Dam).