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• 2.05.6(6) <br />(b)(i)(C) <br />The Bruce Park Main Dam and Saddle Dam should not be affected by <br />subsidence since they lie entirely outside the limits of mining and are more <br />than 2,000 feet above the coal seam to be mined. The location of the mine <br />and its configuration are specifically designed to avoid subsidence or seismic <br />damage to the Bruce Park Dams. <br />GEI Consultants Inc. studied the stability of the main dam and saddle dam <br />during 2001 and 2002. See Volume X, Geotechnical Studies, Bruce Park <br />Dam. The study first determined the strength parameters, foundation and <br />soil types of the dams. The study then evaluated mine induced seismicity on <br />Bruce Park main dam and saddle dam. The basis for the analysis was that <br />mining in the area of the dams would occur over a period of 2 years and <br />would be within 1300 feet of the dam. Permanent deformations were <br />calculated considering a single magnitude 4.2 event and a combination of <br />100 magnitude 1.75 events, 20 magnitude 2.0 events, and 5 magnitude 2.5 <br />events. The study concluded the main dam and saddle dam would be stable <br />. under the assumed seismic loadings. The Applicant has determined the <br />events used in the GEI Consultants study are conservative. See Volume <br />IIIA, Exhibit 18 Seismic Monitoring, Summary Statement. <br />Mine induced seismic activity could possibly cause the Bruce Park <br />landslide to negatively affect the Terror Creek Reservoir. Please refer to <br />the Yeh and Associates, November 6, 2006, Final Geotechnical <br />Investigation and Evaluation Report, Bruce Park Landslide, located in <br />Volume IIIA, Tab 20 for a description of potential mine induced seismic <br />impacts. <br />Ponds could be damaged and drained by a subsidence crack that occurred <br />directly below the pond. The probability of such an event is very low. Any <br />pond affected by a subsidence crack could be repaired by lining the pond <br />with an impervious material such as bentonite or synthetic liner material. <br />PR -12 2.05-140- 06/10 <br />APPRoveD <br />Il /C, /ja <br />