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Accidents Do Happen: Shell Muskeg Tailings Pond

Julia Ko

The Canadian Association of Petroleum Producers (CAPP) released their latest projections for oil sands production, with higher rates of production as new projects come on-line:

“Compared to the 2011 forecast, oil sands production is higher by about 100,000 b/d for most of the forecast period due to the acceleration of some projects before becoming higher by about 480,000 [barrels per day] by 2025 due to the inclusion of additional projects.”[1]

These higher rates of production exceed original estimates as highlighted In the Shadow of the Boom. Oil sands production have already surpassed original 1995 estimates, where by 2020 oilsands would produce between 800,000 to 1.2 million barrels per day, to current estimates of 3.5 million barrels per day by 2020.[2] Increased oil sands development includes mine expansion such as Shell’s Muskeg River Mine Expansion, in which Shell plans to increase production at their Jackpine Mine site from 100,000 to 300,000 barrels per day.[3]

Such substantial growth in oilsands development raises the question of risks of such development to groundwater resources, and whether our knowledge of groundwater in the region is sufficient to prevent harm in the face of oil sands expansion. As we previously highlighted in our Drilling Down report, knowledge and monitoring of regional groundwater and its interactions with surfacewaters in the oil sands region is inadequate to understand the cumulative impacts of oil sands development.[4]

A recent accident at the Shell Muskeg River Mine tailings pond offers an example of how little is understood about the detailed geology of the oil sands region or its groundwater resources.  In December 2010, Shell Canada hit what is suspected to be a deep, pressurized saline aquifer, i.e., a pressurized underground reservoir with high salt and mineral content. Shell Canada hit this aquifer while digging at the bottom of its Muskeg River oilsands mine pit to prepare a tailings pond. The shovel operator was doing the final clean-up of the pit floor when suddenly water started to bubble up from a hole just dug at a rate of more than 2,000 cubic meters per hour. Initially, it was thought that the water was the normal basal (shallow) water that drains out of the land and wetlands surrounding oil sands mine pits in northern Alberta, which is usually just pumped out of the pit into holding ponds. However, it soon became apparent that the water was saline and contained small amounts hydrogen sulphide, indicating that it came from some deep, saline aquifer originating far below the mine pit floor.

As of October, 2011, the saline groundwater was still flowing into what was intended to be a tailings pond but has now become a growing saline water containment pit at the Muskeg River oil sands mine site. Because of its high salinity, the water in the containment pit cannot be allowed to overflow or otherwise emptied into the Athabasca River. During the last year, Shell Canada, the ERCB, and Alberta Environment have been seeking a solution to this major problem, to control and prevent saline groundwater from flowing into the containment pit, or going beyond it.[5] Currently, Shell is considering pumping the saline water to another oilsands company’s facility for use in deep injection.  Another option is to fill the pit with sand, followed by standard industry land reclamation. 

Among other things, this accident clearly demonstrates that the oilsands industry’s normal seismic work to identify regional geological structures is not detailed enough to identify or avoid natural cracks that provide connections between deep aquifers and mines or tailings ponds, such as the 5-meter crack in the capstone under the Muskeg River Mine that resulted in this leak. Because a solid cap-rock barrier is necessary to contain pressures and chemicals used in deep in situ steam injection oilsands recovery, this problem may have important implications that extend beyond just oilsands mine operations.

The Shell Muskeg Mine incident highlights again the need for the Government of Alberta to commit resources to fully mapping and understanding groundwater resources in the oil sands region. Although oil sands companies do collect data and monitor surfacewaters and groundwater, a major problem is that these data are not publicly available. Further, this information is not coordinated or standardized, and therefore even if it were available, it is of little value for anyone interested in doing an independent assessment of regional groundwater resources and oil sands development’s effects on it. As a result, there is limited understanding of the detailed hydrology and geology in the oil sands region, impacts of regional development on groundwater, or how much groundwater can be withdrawn without causing harm. Unfortunately, the recently proposed draft Lower Athabasca Regional Plan (a land-use plan for the oil sands region) does not include any plan to map groundwater resources or movement, or identify sustainable limits of groundwater withdrawals. 

Key facts about the discharge of saline water from the Muskeg site:

  • As of October 15, 2011, Shell Canada’s tailings pond that is now a saline water containment pit had grown to contain more than seven million cubic metres (seven billion litres) of saline water.[6]
  • It will not be clear if the cement plug is successful in stopping the leak until late October 2012.
  • The Total Dissolved Solids (TDS) of the saline groundwater filling the pit is between 28,000 and 30,000 mg/L.  Alberta Environment and Sustainable Resource Development is only regulates water below 4000 milligrams per litre (mg/L) under the Water Acts Ministerial Regulations (205/98).

[1] Canadian Association of Petroleum Producers, Crude Oil: Forecasts, Markets, & Pipelines, June 2012, (last accessed June 7, 2012).

[2] National Oil Sands Task Force, The Oil Sands: A New Energy Vision for Canada (1995), p. 33. And, Alberta Energy Resources Conservation Board, Alberta’s Energy Reserves 2010 and Supply/Demand Outlook 2011-2020, ST98-2011 (2011), Figure S3.8.

[3] “Shell seeks input for Jackpine expansion,” June 5, 2012, Fort McMurray Today (last accessed June 7, 2012).

[4] Julia Ko and William Donahue, Drilling Down: Groundwater Risks Imposed by In Situ Oil Sands Development, July 2011, Water Matters;

[5] Flows eventually reduced to 200 cubic meters per hour.  In early 2012, Shell began a drilling effort to seal the geological crack in the bottom of the pit with a hot asphalt material and grouting cement, expecting to finish by October 2012.

[6] See David Cooper, “Oilsands leak turned mine to pond: Shell finds innovative fix for a never-before-seen problem,” October 15, 2011, Edmonton Journal.

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