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2-11 Significant variability in'permeability,was noted ranging from 1 t 20 x LO -5 cm/sec. The average permeability was approximately 5 x 10-5 i cm/sec. The large variation in values indicates that the fill may consist of differing or layered materials. The soil test results further support this observation. The potential for hydraulic fracturing in the fill was assessed using the piezometers and falling head type permeability tests with various initial excess heads. The rising head test results were compared to the falling head test results. The falling head tests indicate that generally higher coefficients of I permeability were observed with high values of excess head, as compared to the permeabilities observed in the rising head tests. This high coefficient of permeability could be due to hydraulic fracturing of the soil. With time {and reduction of excess' head), the coefficient of permeability value tended to become less and similar to the rising head test results regardless of initial excess head. The rising and falling head test observations indicate that the fill was susceptible to hydraulic fracturingin' places. The potential for hydraulic fracturing could explain the water loss in the grout holes. , The results confirm that low horizontal stresses apparently exist in the da borehole fluid press—'hydr-auIiCRfrattffiri g Gtierefore is present either.,daa ;The potential fosure-or by stresses._exceeding the tensile strength of the soil. "V The piezometer test results and the coupling of genecal observations as discussed in Chapter 4.0 lead to the conclusion that mechanisms exist within the core which allow the vertical permeability to be equal to or greater that the horizontal permeability. The layered nature of the fill, the variation in grain size within these layers, and the potential for micro—cracking to connect these layers indicates that the horizontal