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~. <br />.^. <br />Reporting Period August 4, 1997 -August 11, 1997. <br />3 <br />Substation: Visual observation of the failed slope above the substation on August 6 and <br />August 11 showed no obvious additional movement in the slumped area and no advancement <br />of the head scarp into the Landing #2 Road, even with saturated slope conditions during the <br />entire week. MCC will continue to monitor this slope. <br />Shaft Site #1 and #2: The shallow slope failure on the steep cut slope south of Shaft #1 was <br />pulled down, and a 15' wide by 30' high by 200' long compacted soil buttress was constructed <br />against this slope and backsloped at 1.25:1. This required realigning the Clearwater ditch and <br />culvert, and sediment ditch further into the bench. Overall slope angle (top of cut to bench <br />elevation) is now approximately 1.5:1. When inspected on August 11 after two heavy rain <br />events, no cracking or movement was observed. Outside the slide zone, slopes aze remaining <br />stable at approximately 0.7:1. Excavation of the north slope of the shaft sites is exposing <br />significant massive sandstone, yielding steeper back slopes than designed. These slopes are <br />solid and stable. <br />Electric Borehole Road: As reported previously, six discreet springs at the start of this road <br />were intercepted with lined french drains and routed to Sylvester Gulch. All french drains <br />continue to flow. No additional springs have been encountered. Road cuts and fills (under <br />construction) appear stable. <br />Data Collection and Evaluation <br />Monitoring of inclinometer I-12 at the failed fill area continues. Surface surveys continue to <br />indicate no appreciable movement either above the cut slope or below the fill area. The greatest <br />total movement to date (since July 12) is approximately 0.6' at Station BS located at the toe in the <br />center section of the failure area. Most of this movement occurred within the first week, before <br />the fill material was removed from the slope. <br />A final reading at inclinometers I-4 (approximately Station 30+00) was taken on August 7. Data <br />analysis and re-evaluation of the current design slope at this location is in progress. A third <br />reading at inclinometer I-2 was also taken. Movement is slower than anticipated and the data <br />results aze inconclusive. Monitoring and evaluation of I-2 will continue. <br />Survey data for the substation cut slope shows no movement above the Landing #2 Road or <br />below the finished slope (on the substation pad), however, minor movements of 0.2' to 0.5' have <br />been detected on the slope itself. MCC will continue to monitor and evaluate this slope. <br />Readings of survey prisms above the main shaft site cut slopes indicate that no large scale <br />movement or failure is occurring. Additional hubs will be place on the finished slopes this week <br />to monitor the performance of the slope and buttress that was completed last week. Back <br />calculation of soil strength properties, collection of accurate surface survey data, and re- <br />evaluation of design slope configurations will continue. <br />