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r~ Reporting Period September 30, 1997 -October 7, 1997 Field Observations, Data Collection, and Ongoing Evaluations Page 2 A complete inspection was performed by MCC on October 4, 1997 and October 7, 1997 to visually observe and evaluate the stability of slopes within the project area. Data collection efforts and evaluation or re-evaluation of specific areas of concern continues. Individual areas are discussed in detail in the following sections. Supporting documentation is attached for your review. RPE Access Road: Just north of the Sylvester Gulch crossing, a 50 foot long by 8 foot high by 6 foot deep section of the steep, temporary cut slope broke off and settled about 3 feet. This failure appears to be weather related, and does not appear to represent a larger instability or the precursor to a larger failure. The steep cut slope stood for over three months before shearing off. The failed area is within the excavation limits of the final slope and will be removed and graded in the process of completing the RPE access road. Lower Sylvester Gulch Road: Excavation work is 100 % complete between Stations 37 and 50, and fill operations in this section are almost complete. The additional french drains described in last week's report were completed at the top of the slopes between Stations l9 and 23. Seventeen layers of geogrid at MSE Wall E (Station 50+50 to 54) are now completed (approximately 80%). All slopes beAveen Station 25+50 and 54 (including benched slopes and the locations of french drains) appear stable and no slumping due to the heavy rains was observed. The latest reading on inclinometer I-2 (10/2) showed a large movement in two directions at the surface and minor, but incrementally increased movement in one direction (downslope) at approximately 25 feet depth. The surface movement is attributed to construction equipment which installed a french drain very close to the casing. The movement at depth bears watching. Inclinometer 1-2 will be maintained and monitored during construction and for the long term. Upper Sylvester Gulch Road: The residual failure at approximately Station 63+50 reported three weeks ago remains stable after regrading. Surface surveys continue to indicate no appreciable movement either above the cut slope or below the fill area. Stability analyses and other evaluations of the failed fill area by Golder Associates and Barr Engineering were postponed for a week to allow incorporating the latest survey data. Anew inclinometer, I-13, was installed at the top of the ridge above the failed area. This inclinometer is primarily for monitoring potential slope movement associated with future mine water treatment facilities placed on the ridge (MR to be submitted soon), but should also provide useful information on slope conditions above the failed area. Main Embankment (F-Walls): As reported previously, construction of the F-Walls was finished out at a lower elevation due to concerns over small, but increasing movements at depth observed in inclinometer I-9 and I-]0 on either side of the embankment. The embankment is now complete except for final base course and guardrail. The weekly measurements at 1-9 and I-10 taken on October 2 show continued incremental increases in cumulative movement in the same directions as previously reported. However, movements have slowed, foundation settlement has stopped, and pore pressures continue to decrease. MCC will continue to monitor the inclinometers and piezometers. Landing #2 Road: The light-use road to Landing #2 was inspected on October 7. Soil cut and fill slopes appeared stable throughout the length of the road. Drainage ditches appear to be working properly.