Ontario Power Generation's Response to the Joint Review

Introduction
This Technical Memorandum provides estimates of inflows through the upper 190 m of the shaft, based on
a) the current measurements of hydraulic conductivities of the upper formations; b) the measured hydraulic
conductivities of the grouted rock around the shaft and its extent; and c) the hydraulic conductivity of the
concrete liner, after it undergoes seismic loading.
In Situ Hydraulic Conductivities
Original in situ hydraulic conductivities were reported in Golder’s Documents 1011170042-REP-G2060-0001-
00 [1] and 1011170042-TM-G2090-0001-A [2] and were based on based on 1) the consolidated results of all DGR
borehole hydraulic testing at the time, 2) hydraulic testing of US-series boreholes, 3) core inspection, 4)
observations of fluid loss during drilling of DGR boreholes and US-8, and 5) observations on fluid volume
production and drawdown during opportunistic groundwater sampling of DGR boreholes. Subsequently, a series
of holes were drilled during the grouting trials, and a site specific hydraulic conductivity data set was obtained
based on the following assumptions:
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DATE December 23, 2011 REFERENCE No. 1011170042-TM-G2100-0001-01
TO Serge Clement
Tetra Tech
CC R. Heystee, NWMO
FROM J.L. Carvalho/C.M. Steed EMAIL jcarvalho@golder.com
POTENTIAL INFLOWS THROUGH CRACKED HYDROSTATIC CONCRETE SHAFT LINER
Borehole P1/DGR-7 was drilled and tested before any grouting and is considered to be representative of
the in situ conditions;
Borehole P3 was drilled after borehole P2 was grouted; however, it was drilled at a distance from P2 such
that the test results are considered to be representative of the in situ conditions; and
Due to the observed variability between boreholes P1/DGR-7 and P3, a profile of hydraulic conductivity
based on the highest value of P1 and P3 has been adopted (see Figure 1).
Table 1 shows the weighted average for the hydraulic conductivity by formation before (in situ) and after
grouting.
The shaft will be designed as a sealed system down to the bottom of unit G of the Salina Formation and this
memorandum addresses only inflows through a “cracked” concrete liner above the F unit (exclusive). It is also
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