1991-09-01_REVISION - C1981035 - Laserfiche WebLink

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measured values of each of these tends to increase the stability of the waste bank slope and thus the original assumed values are indeed conservative. The safety factors for the new pile configuration will increase due to the effect of the more stable pile geometry (flatter surface slope) as well as due to the field measured soil parameters. For example, the stability analysis was redone for section 4 resulting in a factor of safety of 4.7. Results are shown on the attached worksheets. 4. Construction Densities State regulations require that waste material be placed in the bank and compacted to at least 90% of the maximum dry density. Soil sample taken from the drill hole were used in a Proctor Test to determine the maximum dry density and the optimum moisture content. The tests conformed to the required AASHTO T99-74 standard procedure. Results are; Maximum Dry Density = 91.0 pcf Optimum Moisture Content = 12.0% Four samples were tested to determine the field density of the existing waste bank. Of these two were reported by Lambert and Associates as, "may have experienced disturbance". The remaining two indicated compaction rates of 91% and 94% and thus conform to the requirements. 5. Drainage Features The eastside drainage channel will be intercepted above the waste pile approximately 50 feet above section 4. A diversion structure consisting of an earthen berm with a pipe inlet will be constructed to divert flow through the pipe and under the pile. Details of the drainage features are given in a separate Technical Revision. As stated in TR1 (April 1991) an intercept ditch is required both at the top and bottom of the pile. The upper ditch will slope from the west end (section 1) to the east end (section 4.3) of the pile and will drain into the eastside channel above the diversion berm. The lower intercept ditch will slope from the east to the west and will enter the main buried diversion pipe through a connector pipe at about section 2.