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March 1991 Coa/ Raluss P/ss/iciry Resulb and Re/sfed Stability lmplicationa 1 2 • The refuse pile is curtemly beirtg mastructed from both coarse and fine refuse materials. Cttrtem placemem proportion is one Gk of firs refttse to orc or more lifts of coarse refuse with the porential for some variance with changes in geologic and mioirtg conditions. It is expected that the 5oe refuse material has lower svength properties, therefore, for the stability analyses it was conservatvely assumed that the entire pile was trade uP of floe refuse. The strength properties assumed for the floe refitse are ~~~~~~ below: Friction Attgle - 33 degrees Cohesion - 0 psf Unit Weight - 50 pcf • r1 LJ The above values were based oo a series of direct shear tests conducted on the floe reftue by GeoWat (1988)'. The direct shear tat results indicted a friction angle of 33 to 35 degrees. The lower end of this range wu conservatively used in the stability analyses. A friction angle of 33 degrees is coosisrem with the sample descriptions and the plasticity tat results presented in Table C-1 and oo Figure C-1. Attached as Attachmem C-4 are published cortelatioas of friction angle with material description and pLtsdciry index (Tenaghi and Peck, 1967)'. Both of the correlations indicate that a friction angle of 33 degrees, under drained conditions, is reasonable for the 5ne refttse. Based on the consistency of test results from samples obtaired from differem parts of the reftue pile a~ from the preparation plain, it is ottr opinion that further taring of the fine refuse material is not wartamed and that the strength properties used in the stability analyses are appropriate. ' GeoWest (1988), "Reevaluation of Refuse Pile Stability for Modified Placement Practices' Terraghi and Peck, 1967, 'Soil Meciwnlcs in Engineering Practice' Second F.ditioa, 1967, John Wifey & Soar, hr. New York, NY. ..~.a.~.r~.. ~.~ ~~w