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some silt and some gravel. The expected hydraulic conductivity of <br />this material, again using the Hazen method, is about 4x10'Z cm/sec, <br />• . which is a relatively free draining material. <br />....The strength of this material has not been measured. However, when <br />- the material is disturbed, it would be expected to be very similar <br />-. to the strength of the waste material noted above. Zn its in-situ <br />condition, it would be expected to have indurated somewhat, <br />- developing a small shear strength. Accordingly strength parameters <br />have been selected as follows: <br />Effective stress angle of friction: 28° <br />Effective stress cohesion: C 100 psf <br />• <br /> <br />3.3 Groundwater conditions <br />The water table has been measured in the AVF study holes and the <br />water levels are reported in Appendix 3.3-6. The results indicate <br />that the water table in the colluvium is in excess of 100 feet <br />below the ground surface at the portal location, and that the water <br />level in the colluvium does not vary significantly on a seasonal <br />basis (a maximum season variation of about 10 feet is indicated by <br />the data). Thus it appears unlikely that the water table would <br />ever approach the surface in this location, and the foundation <br />material is therefore expected to remain drained. This observation <br />is consistent with the high hydraulic conductivity estimated for <br />the colluvium material (above). <br />There are no springs or seeps in the vicinity of the portals. <br />3.4 Surface water conditions <br />There are no surface water streams in the vicinity of the portals. <br />Precipitation is low, and the runoff from the hogback even under <br />major storm events appears to be very limited. <br />Adrian Brown Consultants -6- <br />1145/900531 <br />