Pierre River Mine Project

WATER ERCB SIRS 46 – 79
Section 7.1
Response 52a Table 10-2 from the Pierre River Mine, Project Description, Volume 2 shows the
annual water balance for the Pierre River Mine Project. According to this
balance, the fraction of total water lost to tailings pore space (external and in-pit)
versus total diverted water (Athabasca, basal water and runoff) is greater than
90%.
Request 52b What is the porosity of the sediments in the tailings ponds?
Response 52b The porosity of the sediments in the external tailings disposal area is shown in
Table ERCB 52-1.
Question No. 53
Table ERCB 52-1: Predicted Tailings Sediment Porosity
External Tailings In-Pit
Sediment Type Type Disposal Facility Facilities
Coarse tailings Cell 0.37 -
Beach 0.43 0.43
Thickened tailings – 0.68 0.64
Mature Fine tailings – 0.85 0.85
TSRU tailings Solids 0.65 0.65
Hydrocarbons 0.07 0.07
Non-segregating tailings On-spec - 0.39
Off-spec - 0.42
Request Volume 1, Section 13.1, Page 13-21, Supplemental Information Responses.
Shell states, “Treatment of water would not reduce the total volume of water
required to fill the pit lakes,” and “Maximizing the reuse of process-affected
water released by tailings will minimize the amount of process-affected water
inventory at the end of mine life.”
53a How do these two quotes relate to one another?
Response 53a The statements are unrelated.
The first statement points out that, even by treating and reusing process-affected
water throughout the operating mine life, there will be no change in the amount
of water required to fill the pit lakes because, regardless of treatment, all
available water is used in the extraction process.
The second statement explains that Shell’s process-affected water inventory near
the end of the mine life is primarily the result of releasing water from nonsegregating
tailings as it consolidates over time in the backfilled mine pits. Shell
7-6 Shell Canada Limited April 2010
CR029