Sept/Oct 2009

Balancing the flows

An examination of Athabasca’s Water Management Framework

By D. Zlotnikov

Suncor’s primary extraction plants separate raw bitumen from the sand in giant separation cells.

Like other regions rich in natural resources, Alberta has had to strike a balance between protecting the environment and embracing economic growth. Previously, this equilibrium would have been defined by Canada’s strict regulations on emissions and water withdrawals. But the situation in the Athabasca Basin was unique in the rapidity and concentration of its economic development. One of the greatest areas of concern for local stakeholders and for national and international non-governmental organizations was the welfare of the Athabasca River.

The Athabasca experiences significant seasonal variations in flow rates, explains Preston McEachern, a section head in the Oil Sands Environmental Management Division at Alberta Environment. McEachern is one of the primary authors of that ministry’s response to the ecological challenge of protecting the river — The Water Management Framework.

The framework, currently in the first of two phases, focuses on the Athabasca’s overall flow during any given week. The flow is highest in summer, explains McEachern, due to the contribution of snowmelt and various surface water bodies and tributaries. In winter, when these additional inflows are absent, the flow rate drops significantly.

Water is an integral part of the extraction process used today, explains Chris Fordham, manager of strategy and regional integration at Suncor. “The ore is mined, broken up in sizers, and water is added to it to create the lumpy slurry that goes to the extraction plant,” he says. “There, more hot water is added, causing the bitumen to float off. The water stays with the remaining material – the tailings.” More water is needed for the high-pressure chemical upgrading processes, which converts bitumen into lighter crude. Currently, all the operations draw their water from the Athabasca River.

The framework’s rationale is that as more projects come online, the pressures on the river will increase, necessitating the evaluation and control of the cumulative, rather than just individual, effect of the water withdrawal licenses. To this end, the framework introduces three colour-coded conditions which, along with associated restrictions, are adjusted weekly.

Under the “green condition,” when flow rates run high, each operator may withdraw water up to the limit set by its water usage license, as long as the cumulative withdrawals of all the operating projects are less than 15 per cent of overall river flow. Given that historically, as McEachern notes, “withdrawals have accounted for less than one per cent of annual flow,” the cumulative limit is unlikely to overly constrain operators.

During “yellow conditions,” when river flow decreases to the lowest 20th percentile of historical values, the cumulative constraint is more likely to be felt. During such times, combined withdrawals must not exceed 15 cubic metres per second (cumecs) during the ice-covered periods, or 34 cumecs during other times.

Restrictions are strictest during the dry “red condition,” when river flows are in the bottom fifth percentile of historical rates. The withdrawal limit is set at the lesser of 15 cumecs or five per cent of median flow in each week. During winter, this would typically amount to between 8 and 12 cumecs.

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