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current ground water seepage into Streeter Creelc, and fill <br />Permeability cannot be reliably evaluated at this time. How- <br />ever, based on some pessimistic assumptions of infiltration <br />and fill permeability, it appears that a significant increase <br />in the ground water levels could possibly occur. These <br />r pessimistic assumptions would correspond to little or no <br />I control of surface runnoff, lac:c of a final waste dump <br />surface seal, and a relatively low waste dump permeability <br />of about 1 ft./day. The initial waste dump material we <br />observed during our site visit was quite silty and probably <br />has a permeability on the order of 1 ft./day. <br />Ne evaluated the long-term waste dump stability using <br />a simple sliding block analysis. This procedure effectively <br />assumes that the failure surface would lie along the top of <br />the existing ground surface. A conservative friction value <br />of 30° was used to compute the active pressure within the <br />~• waste dump. Figure 2 shows the results of the analysis and <br />indicates the general geometry of the sliding block analysis. <br />For any reasonable assumption of friction angle, a 4:1 slope <br />appears stable even far the extreme condition of maximum <br />ground water rise (fill saturation, ground water gradient of <br />4:1). Assuming no water buildup within the waste dump fill, <br />a 2:1 slope also appears stable for any reasonable assumption <br />~. of soil strength. On the other hand, should the maximum <br />ground water rise occur, a 2:1 slope would clearly be unstable. <br />The stability of a 2:1 slope for conditions of partial fill <br />saturation may be marginal. <br />To examine the limiting case of short-term stability during <br />fill placement, a circular failure surface was analyzed assum- <br />ing simple undrained strength behavior (so-called ~ = O <br />~ analysis). It was assumed for this short-term condition that <br />I~ <br />L_ <br />t_._ <br />t? <br />