Pierre River Mine Project

WATER AENV SIRS 15 – 43
The typical steps in designing and implementing a detailed groundwater
extraction system include:
Section 12.1
• updating the hydrogeological model to include additional geological and
hydrogeological information and any modifications to ETDA design. This
typically includes updates on hydraulic conductivity, aquifer thickness,
groundwater flow direction and velocity, and subsurface chemical behaviour.
• updating the groundwater flow model based on the updated hydrogeological
conceptual model to assess the seepage management system components, to
clearly define groundwater extraction rates, and to define the expected
performance of the seepage management system
• designing a seepage management system, including designing:
• the extraction system, including the number and location of wells, well
diameters, screen perforation and length, filter pack specifications, and
completion intervals
• the horizontal drains and interceptor trenches, including the depth and
width of trenches, diameter, perforation size and slope of collector pipe,
sand and gravel pack specifications, and maintenance manholes
• the collection system, including the pipe diameter and length and pump
specification
• the surface infrastructure, electrical systems, instrumentation and
controls
• installing and commissioning the seepage management system
Shell expects to start designing its seepage management system about 18 months
before construction of the ETDA begins. Constructing and implementing the
seepage management system will take between 12 and 18 months, and coincide
with start-up of the ETDA.
Request 17e Shell mentions they are aware of publicly reported information on seepage from
ETDA at other facilities but are unable to provide details of the suspected causes
of the exceedence events or how the interception measures implemented will
function.
i. Describe and discuss the known causes of seepage that are being considered
for the design and construction of the seepage interception system.
ii. In the event that seepage rates exceed the interception system what are the
contingency design and construction measures that will be used?
Response 17e i. External tailings disposal area seepage occurs as a result of the elevated fluid
level in the ETDA relative to the groundwater level in the underlying
April 2010 Shell Canada Limited 12-9
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