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<br />1 <br /> <br /> <br /> <br />1 <br />t <br /> <br /> <br /> <br />1 <br /> <br /> <br />1 <br />1 <br />Ll <br /> <br />1 <br /> <br />II. BACKGROUND <br />2.01 Mine Plan Amendments <br />Mine Plan Amendments Nos. 3 and 4 revised the approach to slope design at the Morrison <br />Quarry with the implementation of the Observational Method throughout the quarry. The <br />significant changes presented in these Amendments were a reconfiguration of the east side of <br />the Central Quarry to address slope instabilities in that area and the provisional change in <br />slope inclinations elsewhere [o as steep as O.SH:1 V based on evaluations of preliminary <br />slopes established at 1H:1V. As a condition of the Amendments, the steeper slopes and <br />revised configuration could be implemented only in accordance with specific, predetermined <br />steps outlined in the Observational Method. Conditional approval of the Amendments <br />required annual reporting of geotechnical data, slope stability evaluations, attd current mine <br />conditions in areas where steeper slopes were utilized, or where unusual conditions were <br />encountered. <br />2.02 Observational Method <br />The Observational Method as described in Mine Plan Amendments Nos. 3 and 4, is a step- <br />wise approach to slope design by which new information is regularly used to upgrade <br />previous analyses. This method was utilized as a practical approach [o designing slopes in a <br />rock mass with variable conditions, in which some areas are poorly exposed and difficult to <br />characterize. This method establishes baseline conditions during initial evaluations. <br />Observed initial conditions are then compared with the baseline for analyses. As a required <br />condition of permit approval, annual geotechnical reports are presented to provide the <br />opportunity for periodic regulatory review of geotechnical conditions relating to mining <br />activities. <br />The Observational Method is applicable to any slope in the quarry, except the West Highwall <br />of the Central Quarry, which is steeper than 1H:1V. The method also applies to the east side <br />if the slope is altered from the previously approved slope reconfiguration of 1.5V:1H. <br />' G'~PROIECTS\]0200 Morriwn QW(ryl~1~MYL Rcpan Grni¢Mi.al AJdmEum~1998~98ry~ mukup dw Page 2 <br />