Pierre River Mine Project

WATER AENV SIRS 15 – 43
Question No. 28
Request Volume 2, SIR 294e, Page 21-49.
Section 12.1
The assumption that storage capacity for a given surface area of a pit lake is
greater than that of a wetland is misleading because it is not the surface area but
rather the ‘active’ depth or volume that is critical in relation to patterns of water
storage, retention and release. Peat soils and living Sphagnum may retain well
in excess of their weight by volume of water, and in doing so, they buffer the
rates at which fluxes of water storage, retention and release occur.
28a Provide data and information to demonstrates how pit lakes will be regulated to
respond in the manner that the natural wetland systems operate (e.g., in terms of
mimicking time lags), in particular in relation to typical fluxes that occur, such
as from storm and flood events, and extended periods of desiccation/drying.
Response 28a The pit lakes will not be regulated (designed) to respond to various storm events
in the same manner that the natural wetland systems operate (i.e. the pit lakes are
not expected to exactly mimic the natural wetlands in terms of storage capacity
and time lags to attenuate floods). Therefore, the reclaimed landscape will have a
different hydrological response compared to natural conditions. The effects of
this change in hydrological response are captured in the surface water hydrology
assessment (see EIA, Volume 4A, Section 6.4.5).
Question No. 29
Request Volume 2, SIR 297a, Page 21-51.
Shell states that Modeling has been completed to confirm that the residence time
will be sufficient to biodegrade organic constituents to acceptable levels.
29a Indicate where in the EIA this modeling is reported and assessed in relation to
this question. If it is not in the EIA, provide the data and information.
Response 29a Pit lake water quality modelling methods are presented in the EIA, Volume 4B,
Appendix 4-2, Section 2.1.3.2; pit lake modelling results are presented in EIA,
Volume 4B, Appendix 4-7, Section 4; assessment of modelling results is
presented in EIA, Volume 4A, Section 6.5.6.3.
April 2010 Shell Canada Limited 12-41
CR029