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Geotechnical Evaluation of Mine-Induced Earthquakes on Bruce Park Dam <br />Bowie Resources, Limited <br />June 2002 <br />t? <br />Section 1 - Introduction <br />1.1 Purpose and Objectives <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. The location of Bruce Park Dam is <br />shown on Figure 1.1. <br />The intent of the analyses is to evaluate the likely impacts of mine-induced seismicity on the <br />main dam, saddle dam, and landslide. The locations of the main dam, saddle dam, and <br />landslide are shown on Figure 1.2. Analyses to evaluate the stability and safety of the main <br />dam, saddle dam, landslide, and other appurtenants from other loading conditions and from <br />tectonically induced earthquakes are not part of this work. <br />1.2 Background <br />lip The Soil Conservation Service constructed the original Bruce Park Dam in 1940 with a <br />structural height of 41 feet. Bruce Park Dam was raised to a reported structural height of 58 <br />feet between 1950 and 1952 (main dam). At the same time an auxiliary or saddle dam was <br />constructed on the opposite end of the reservoir to a reported structural height of 28 feet. <br />( Bruce Park Dam was re-classified by the Office of the State Engineer (SEO) from a Class III <br />! (low hazard) dam to a Class I (high hazard) dam on December 4, 1990. Bruce Park Dam and <br />_ Reservoir are owned and operated by Terror Ditch and Reservoir Company. <br />As part of Bowie Resources Limited (BRL) submittal for Technical Revision No. 22 9TR- <br />22) to a Division of Minerals and Geology (DMG) permit, BRL was required to gather data <br />on the geotechnical characteristics of Bruce Park Dam and evaluate the probable <br />geotechnical response of the dam to mine-induced seismicity. The proposed mining is <br />anticipated to be located approximately 2,100 feet below the ground surface and could be as <br />close as 1,300 feet to the dam site. BRL retained GEI Consultants, Inc. (GEI) in November 2000, to collect geotechnical data <br /> <br />and to perform engineering evaluations to identify the probable response of the dam and <br />landslide to mine-induced seismic events. The geotechnical data collection was completed in <br />two phases: <br />02-05-22 Geotechnical Evaluation of Mine-Induced Earthquakes <br />GEI Consultants, Inc.