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some silt and some gravel. The expected hydraulic conductivity of <br />`~j~ 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 measu_~ed. However, when J <br />-._. ., ••:::the material is disturbed, it would be expected to be very similar <br />_.._..-.. .. to the strength of the waste material noted above. In its in-situ I <br />_.. - condition, it would be expected to have indurated somewhat, <br />-.developing a small shear strength. Accordingly streng-`rh parameters 1 <br />have been selected as follows: <br />Effective stress angle of friction: ~ 2E° <br />_.-_ .....- . Effective stress cohesion: ~ 100 psf <br />•~..- 3.3 Groundwater conditions <br />The water table has been measured in the AVF study holes and `..he <br />,, .water levels are reported in Appendix 3.?-6. The resLlts indicate <br />-= that the water table in the colluvium is in excess of 100 feet <br />._.,_.._-_= below the around surface at the portal location, and that the water <br />=.-,-_-:=.:;-:-_level in the colluvium does not vary sicnificantly cn a seasonal <br />-~...a 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 />i material is therefore expected to remain drained. This observation ~, <br />~' ~• is consistent with the high hydraulic conductivity estimated for <br />`she colluvium material (above). <br />There are no springs or seeps in the vicinity c° the pcrtals. <br />3.4 Surface water conditions <br />There are no surface water streams in the vicin_ty of the portals. <br />Precipitation is low, .and the runoff from `she hogback ever. under <br />major storm events appears to be very limited. <br />..-• - -, <br />• `~ Adrian Brown Consultants -6- _1t5/9oc53: <br />