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7. Bedrock exposures at the site primarily reveal foliation jointing subparallel to <br /> metamorphic compositional layering. The foliation strikes northwest and dips <br /> from shallow to moderately steeply to the northeast, generally into the hillside <br /> that is being mined. Secondary joints that are steeply dipping to subvertical also <br /> occur. Finally, tertiary joints exist that dip northwest to southwest, or generally <br /> out of the hillside that is being mined. <br /> 8. Analysis shows potential slope failures if the slope were steepened to 1:4 from the <br /> originally proposed 1:2 configuration,but acceptable slope conditions for a quarry <br /> development if steepened to 1:3 as Elk Creek is presently proposing(12 ft <br /> benches by 35 ft highwalls= 1:2.9). <br /> 9. For the proposed 1:3 slopes, our analyses indicate that sliding failure is <br /> kinematically admissible only on the westerly dipping joint set,but that this is <br /> mechanically admissible only in the upper weathered rock. Toppling failure is <br /> not kinematically admissible for any of the six joint sets analyzed. Several wedge <br /> failure modes are kinematically and mechanically admissible in the upper <br /> weathered rock, but not in the general rock mass. The upper weathered rock <br /> should be laid back to 1:1. Limited individual wedge failure in final individual <br /> highwalls is usually considered acceptable in quarry operations. <br /> LIMITATIONS <br /> Brierley Associates prepared this report in a manner consistent with the level of care and <br /> skill ordinarily exercised by members of the engineering community currently practicing <br /> in Colorado subject to the time limits and physical constraints applicable to this report. <br /> No other warranty, express or implied,is made. <br /> This report has been prepared for the specific site,development and purpose described to <br /> Brierley by Elk Creek. The data,interpretations and recommendations contained herein <br /> pertain to this specific project and are not applicable to any other project or site location. <br /> Furthermore,they are for the sole benefit of Elk Creek. No other party may use or rely <br /> on this report or any portion thereof for other benefit without the express written <br /> permission of Brierley. <br /> Slope stability evaluations included in this report are based on the referenced data <br /> available at this time and on the proposed slope design by Elk Creek. If,during <br /> construction, subsurface conditions are encountered in the future that differ materially <br /> from those described in this report,Brierley should be contacted and allowed to review <br /> said conditions and reevaluate the conclusions and recommendations provided at this <br /> time. If Brierley is requested to provide future assurances about conditions not materially <br /> differing from those presently assumed and/or about the stability of final slopes <br /> constructed in the future, adequate field review, observation and evaluation by Brierley <br /> will be required. <br /> Finally, all conclusions and recommendations about slope stability are based on final <br /> slope configurations proposed by Elk Creek and assumed to be constructed in a safe <br /> manner with the level of care and skill ordinarily exercised by members of the mining <br /> JC 00775 <br /> PetersonlElk Creek <br />