Ontario Power Generation's Response to the Joint Review

Serge Clement 1011170042-TM-G2100-0001-01
Tetra Tech December 23, 2011
circular hole in an infinite medium and take into account three zones of different hydraulic conductivity, i.e., the
concrete liner; the grouted zone and the in situ rock (see Appendix B). The head difference between the far
boundary (Lake Huron – approx. 1000 m from the shaft) and the shaft is assumed to be equivalent to the
hydrostatic pressure to ground surface, which, for the lower formations, does not take into account the depressurization
of the formations above them, making the estimates conservative.
It has also been assumed that the hydraulic conductivities of the in situ rock as well as the grouted rock will not
change after a seismic event. The rationale behind this assumption is based on the fact that the rock formations
are under a compressive stress state which is considerably higher than the stress changes induced by a seismic
event. Therefore, no tensile stresses will be present which could either open existing fractures or create new
ones.
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