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NOTES - MLRD BOARD PRESENTATION <br />HOMESTAKE PITCH PROJECT <br />GEOTECHNICAL TOPICS <br />A. North-Pit Landslide: <br />1. The revision includes amended post-mining topo to accommodate slide. <br />2. Slide history: <br />a. Originated in August, 1979 (Slides - June, 1980) <br />b. Began to overpower pit in 1983 (Slides - Se tember, 1983) <br />c. Continuing to adjust (Slides - August, 1984 <br />3. Analytical results <br />a. Call & Nicholas project equilibrium wi <br />the pit were backfilled or 10 years if <br />b. Equilibrium will be achieved when rate <br />per year. <br />1. Maximum observed rates of movement <br />2. Recent observed rates of movement <br />3. Criterion for stability - 6 inches <br />Il be reached in 5 years if <br />the pit isn't backfilled. <br />of movement decreases to 6" <br />- 30 feet/day <br />- tens of feet per year <br />per year <br />4. Homestake has recognized its ultimate responsibility: <br />"Homestake is aware of its responsibility for reclaiming the landslide <br />area regardless of the time involved (rate of adjustment) in reaching <br />the "final" equilibrium configuration. Homestake does not plan to <br />grade the slide area prior to its reaching equilibrium conditions, nor <br />is it anticipated that any major grading effort would be desirable or <br />appropriate after the equilibrium conditions are met. In order to <br />accomplish minor grading to reduce locally steep slopes and fissures <br />located near the head of the slide area, and thus to reduce the <br />potential for erosion and increase the stability for revegetation, <br />adequate surety has been incorporated in the calculations for <br />Exhibit L. These minor grading activities have been termed 'final <br />dressing'." <br />(August 31, 1984 Submittal Letter - Homestake Mining - pg. 3) <br />5. Homestake has committed to performance of a quarterly slope stability <br />monitoring program, in order to monitor the rates of movement within <br />the landslide mass. <br />6. Exhibit L Includes: <br />Pit wall topographic monitoring $16,000.00 <br />Final Dressing <br />Regrade East Wall (North Pit) Tension Crack $26,460.00 <br />Revegetation <br />2.5:1 Slope on East Side of North Pit $44,400.00 <br />Permit#: h'6- 9Z2-©b Confidental?: <br />Class c2AL Type-Seq.: <br />From: !"C To: <br />Doc. Name: M t_ r C7 l5r~ t ~ <br />Doc. Date (if no date stamp): - <br /> <br />