Geotechnical News March 2011
53
WASTE GEOTECHNICS
Fate and Transport of Process-Affected
Water in Out-of-Pit Tailings Ponds in the
Oil Sands Industry in Canada
Alexander Holden, Trevor Tompkins, Shama Haque
Leo Perez, Heather Sutherland, Mike Bowron
Kevin Biggar, Rob Donahue, Carl Mendoza
Jon Martin, K. Ulrich Mayer, Jim Barker
Dave Sego, Ania Ulrich
Introduction
Due to operational necessities in the
oil sands industry, above-grade tailings
ponds are constructed to store tailings
and process-affected (PA) water before
their ultimate placement is realized
within the excavated, open-mine pits.
Due to local geological depositional
histories and operational considerations
and constraints, there are a number
of locations where the placement of
these impoundments will occur atop
natural, buried outwash deposits,
relicts from previous glacial rivers.
If no engineered measures are taken,
these sand channels have the capacity
to act as potential flow paths for PA
water to migrate away from the tailings
ponds and into downstream surface
or ground waters. Flow and transport
modeling of a case study site suggests
that PA seepage may occur downward
through glacial till deposits into an
underlying sand channel; however,
the potential impact of the PA water
on native sediments and groundwater
resources is not known. Suncor Energy
Inc.’s South Tailings Pond (STP),
with approximately 8km and 50%
of the footprint of its dyke structure
atop the Wood Creek Sand Channel,
represents the first known such facility,
and offers the opportunity to develop
better understanding and management
techniques for this particular challenge.
A long-term research initiative has
been established between the Universi-
ties of Alberta, Waterloo, and British
Columbia and Suncor Energy Inc., with
the principal objectives being: 1) to un-
derstand the fate and transport of PA
water through native sediments; and 2)
to explore different remediation strate-
gies for PA water-impacted groundwa-
ter, ranging from monitored natural at-
tenuation to in situ chemical oxidation.
This paper provides a description of the
field site and the various research ac-
tivities, with an emphasis on the field
experiments that are being conducted.
Site Details
The STP (Figure 1) covers an area
of approximately 2300ha with an
approved, current tailings holding
capacity of 230Mm
3
. The STP is
designated for storage of PA water
and fine tailings, and deposition
commenced June 2006. Three
Figure 1. Schematic of the South Tailings Pond, showing the underlying Wood
Creek Sand Channel (WCSC) in yellow and the approximate locations of the Infil-
tration Pond, Groundwater Monitoring Transect and In Situ Aquifer Test Facility.
