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Page 9 <br />Fred Banta <br />Dean Massey <br />February 6, 1980 <br />P,ecent research conpleted in Kentucky analyzed the shear strength of <br />spoil rinks. (.Huang) Triaxial and simple .shear tests were performed o.. <br />16 fills throughout eastern Kentucku. a Least seuare correlation of test <br />results determined that these fills exhibit an effective cohesion of 2GG <br />pounds pet square foot and an angle of internal friction of approximately <br />30°. Kentucky spoils may be higher in shale content than the Stre=t'r s~^i3. <br />The consultant's report presents no spoil gradation or lithologic data with <br />which to discern comparative spoil constituency. <br />7. The consultant's remrt indicates that the spoil material was placed by <br />dumping. The author observed, ". the material segregates itself into <br />laroe cobble and boulder size material at the tee of each lift. This natural <br />segregation creates a highly permeable zone at the bottom of each Lift ;/hich <br />essentially prscludes tf!e develooment of a high water table." Unfortunately, <br />this same segregation also rewlts in the formation of zones of relatively <br />impermeaole finer spoil fraction material in the upper portion of each dumped <br />1i ft. This zone of concentrated fine fraction could develoo the detrimental <br />characteristics of cohesive clays and silts, and serve to develop perched <br />water taoie conditions. ~~ <br />• <br />8. Reference is made to underground mine workings beneath the Streeter . <br />fill. It is observed t.`~at tae affect on stability should be negligible and <br />the underground workings could serve to dewater the subsurface. beneath the <br />fill. However, it is also wssible that subsidence could disrupt the fill. <br />Subsidence of the fill foundational area could create zones of lowered density <br />within the fill. These disrupted zones could allow infiltration of surface <br />runoff into peripheral areas of the fill which could deleteriously affect <br />fill stability. <br />In summary, I have discerned a number of critical assumptions embodied <br />in the analysis performed for the O.S.Pf.,oy C.T_L. Thompson. The cumulative <br />impact of these factors could render the origiral analysis insigrificant. The <br />analysis is devoid of specif_'c soils testine data :/ith which to accurately <br />appraise the soil shear strength character of the materials involved in t,9e <br />slope stability analysis. Ideally, the appropriate soils testing and ground- <br />water observations stx~uld be conducted to decrease the necessity for assumction <br />and increase the. amount of hard soil mechanics data. The consultant's analusis <br />of parameter accuracy should be expanded. In r_he absence of additional t=sting <br />dace more conservative shear strength values should be analyzed. Ir. addition, <br />scrutinu should be focused upon the cumulative effect of simultaneous <br />parameter variations. <br />(coat 'd) <br />• <br />