1987-12-01_PERMIT FILE - C1981017 (289)

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Most of the road cuts experience only minor sloughing and • erosion problems. Occasional moderate instability is due to slope erosion and sloughing. A zone of important instability was identified where very severe erosion gullies occur in high, steep soil cuts. Fill slopes generally experience only minor instability. Moderate erosion rills occur locally near the end of the road. Road F (see Table 9) from the junction of E- and G-roads to No. 3 mine bench is 13, 400 feet in length, with an average grade of 8. 5%. Again, most of the road is constructed in cut and fill . The majority of cuts are in rock. Heights of cuts range up to 60 feet, with the larger portion of them less than 20 feet in height. Most cut slopes range up to 600 , with a significant number at up to greater than 600, and a few of 400 or less. The greater portion of fill slopes are less than 20 feet high, but many are up to 40 feet or more in height. Most fills are constructed at the angle of repose (30 - 450) ; a few are placed at less than 300. Only minor stability problems are found in most of the cuts. Moderate stability problems consist of sloughing , and rockfall from rock cuts. Important stability problems are large sloughs and slide areas. A major, large-scale slide area lies above the road between stations 53+00 and 57+50 in a zone of soils. The slide extends to a much greater height than the road cut, and may not be related to road construction. Most fill slopes also experience only minor instability problems. Oc- casional stability problems consist mostly of sloughing and rilling due to erosion. Important fill instability problems are major rilling and gullies, . and rare large sloughs. Road G (see Table 10) to No. 5 mine bench from the junc- tion of E- and F-roads , has a length of 19, 700 feet, with an average grade of 2.7%. Nearly half of the road length is in cut and fill construction, and approximately 250 or the road has no significant earthwork. Cuts are distributed between soil and rock. The majority of cuts are less than 40 feet in height, although a few are up to 60 feet high. Slopes of cuts are generally steep; mostly up to 600, and occasionally steeper than 600. Cut slopes near the end of the road , at the mine bench, are essentially flat. Most fills are less than 20 feet in height, with a few ranging- to more than 40 feet high. Most fill slopes are at 30 - 450 , the approximate angle of repose. Rare areas of fill , which are essentially flat, occur along the road . Stability problems in the road cuts are distributed over a range from minor to important. Minor problems include minor erosion and sloughing. Moderate instability occurs primarily in . the form of sloughs. The G-road is unique in that it has large segments of cut which experience severe instability. This 26 GE44(YDR0 CONSULTING.INC.