Laserfiche WebLink
Geotechnical Evaluation of Mine-Induced Earthquakes on Bruce Park Dam <br />Bowie Resources, Limited <br />June 2002 <br />Executive Summa <br />The purposes of this report are to present a) the results of engineering analyses of mine- <br />induced seismicity on Bruce Park Dam and on a landslide on the right (looking downstream) <br />side of Bruce Park Reservoir and b) our opinions regarding possible impacts to Bruce Park <br />Dam and the landslide from mine-induced seismicity. <br />For the purpose of the analysis, we considered that the proposed mining activity near the dam <br />and reservoir would take place over a period of 2 years. Permanent deformations were <br />evaluated for two conditions: a single magnitude 4.2 mine-induced seismic event and <br />cumulative effects of a combination of 100 magnitude 1.75 events, 20 magnitude 2.0 events, <br />and 5 magnitude 2.5 events. <br />Based on the results of the evaluations performed and documented in this report, we <br />conclude the following: <br />1. Bruce Park Dam and Bruce Park Saddle Dam should not be adversely impacted from <br />mine-induced seismicity generated from long wall mining at the Bowie Resources <br />mine for the following reasons: <br />.J <br />a. The dams and foundations consist of clays soils that are not susceptible to <br />liquefaction during seismic loading. <br />b. Permanent deformations of the dam and saddle dam during seismic loading <br />should be insignificant because the expected ground motions (accelerations) at the <br />dam and saddle dam sites are less than the computed yield acceleration. <br />2. The computed static factor of safety for the existing landslide depends on the pore <br />water conditions in the slope and would range from about 1.1 to 2.0 for phreatic <br />surfaces ranging from the ground surface to the top of bedrock, respectively. <br />3. A permanent deformation of about 9 inches may occur in the existing landslide if a <br />rare magnitude 4.2 mine-induced seismic event occurs under conditions where the <br />phreatic surface in the landslide is at the ground surface. If the phreatic surface is at <br />mid-depth or at the bottom of the landslide, a rare magnitude 4.2 event would <br />generate permanent deformations of 1.5 and 0.3 inches, respectively. <br />4. No cumulative deformation of the landslide is expected if the phreatic surface is at or <br />below the mid-depth of the landslide and mining activities over a 2-year period <br />02-05.22 Geotechnical Evaluation of Mittc-lnduced Eanhquaka <br />GEI Consultants, Inc.