Tailings Management Plan – Ready-to-Reclaim Criteria – Fluid Tailings Profiles – Water-capping Technology
In this decision, the AER considered Canadian Natural Upgrading Limited’s (“CNUL”) application pursuant to section 13 of the Oil Sands Conservation Act (“OSCA”) for approval of its tailings management plan (“TMP”) for the Muskeg River Mine (“MRM”).
The application sought approval for the TMP to 2115, which was 57 years beyond the MRM’s end of mine life.
For the reasons summarized below, the AER approved CNUL’s application, subject to terms and conditions (the “Approval Conditions”).
Regulatory Scheme
Tailings are a by-product of the process used to extract bitumen from mined oil sands and consist of water, silt, sand, clay and residual bitumen.
The AER regulates tailings from oil sands mining operations to ensure that the tailings are managed in an efficient, safe, orderly and environmentally responsible manner over their entire life cycle.
The AER applies a risk-based approach to regulating, where higher-risk activities receive the greatest regulatory oversight. Given the nature and scale of fluid tailings generated by oil sands mine operations and the ongoing research and development of tailings treatment technology, fluid tailings management is one of Alberta’s higher-risk industrial activities.
The Government of Alberta regulates tailings under the Lower Athabasca Region: Tailings Management Framework for Mineable Athabasca Oil Sands (“TMF”). The AER noted that following regarding the TMF:
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The TMF’s objective is to minimize fluid tailings accumulation by ensuring that fluid tailings are treated and reclaimed progressively during the life of a project, and all fluid tailings associated with a project are ready-to-reclaim (“RTR”) within 10 years of the end of mine life.
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The TMF establishes four outcomes: land use must be returned to Albertans, sustainable ecosystem, liability is minimized to Albertans, and environmental effects are managed.
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As part of the implementation of the TMF, the AER released Directive 085: Fluid Tailings Management for Oil Sands Mining Projects (“Directive 085”), which sets out requirements for fluid TMPs, including both existing fluid tailings (i.e., legacy) and new fluid tailings.
Approval Until September 2021 and AER Directed Amendment Application
The AER found that:
(a) there was sufficient information to authorize CNUL to manage its fluid tailings and treated tailings deposits for the next few years based on the Approval Conditions;
(b) however, the AER was unable to assess whether CNUL would be able, over the medium and long-term, to manage its fluid tailings and treated tailings deposits to meet the TMF’s objective and Directive 085 requirements due to uncertainties and deficiencies in the application
The AER, therefore, included the Approval Conditions to address these uncertainties and deficiencies, including requiring an amendment application be submitted by September 30, 2021.
The Approval Conditions addressed the following:
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amendment application requirements;
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project-specific thresholds for both new and legacy fluid tailings;
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tailings treatment technology and deposit performance plans and updates over the short term in support of the medium- and long-term management of fluid tailings, including mitigation measures and research, monitoring, evaluation, and reporting;
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stakeholder and indigenous community engagement; and
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environmental effects and implications.
Fluid Tailings Profiles and Project-Specific Thresholds
The TMF defines new fluid tailings as fluid tailings that are produced after January 1, 2015. All new fluid tailings must be RTR within ten years of end of mine life.
New Fluid Tailings Profile
The AER found that CNUL’s new fluid tailings profile met the TMF and Directive 085 profile guidance only until December 31, 2022.
As a result, the AER did not authorize the end of mine life target. The solid blue line in the figure below depicts the authorized new fluid tailings profile that CNUL must achieve until December 31, 2022. The dotted blue line in the figure depicts the AER’s medium- and long-term expectations for the new fluid tailings profile. The dotted red line in the figure depicts CNUL’s proposed new fluid tailings profile.
Specifically, the AER found that CNUL’s proposed new fluid tailings profile beyond 2022 did not meet the TMF’s objective or the TMF and Directive 085 profile guidance for the following reasons:
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The TMF and Directive 085 expect that projects manage new fluid tailings for expected volumes produced during 3 to 10 years of full production. Based on this the AER found that CNUL’s proposed fluid tailings profile resulted in peak accumulation of 127.8 million cubic metres (Mm3), representing about 15 years of full production.
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CNUL proposed growth in tailings accumulation until 2054, a period of nearly 40 years to accumulate the peak volume.
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CNUL had not demonstrated that the fluid tailings treatment capacity was equal to or greater than the new fluid tailings production rate, as required by the TMF and Directive 085.
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The end of mine life target was greater than five years of fluid tailings production at MRM. The TMF and Directive 085 require the end of mine life target to be the equivalent of five years or less of fluid tailings accumulation. Based on a production rate of about 8.5 Mm3/year, CNUL’s end of mine life target would be about 43 Mm3 instead of the proposed 120 Mm3.
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The proposed new fluid tailings profile did not demonstrate that all new fluid tailings generated at the MRM would be RTR within 10 years of MRM’s end of mine life (2058).
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The TMF and Directive 085 require profiles to be project specific. The AER found that CNUL’s new fluid tailings profile included fluid tailings volumes generated from froth transferred to the MRM from the Jackpine Mine. Profiles are required to track project-specific fluid tailings volume, regardless of fluid or treated tailings storage and final placement locations.
To address the concerns, in the amendment application CNUL is required to provide a revised new fluid tailings profile that:
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is representative of MRM tailings only; and
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includes an end of mine life target that is no greater than five years accumulation of fluid tailings production at MRM.
Legacy Fluid Tailing Profile
Legacy fluid tailings are fluid tailings that existed before January 1, 2015. All legacy fluid tailings must be RTR by end of mine life.
The AER found that CNUL’s legacy fluid tailings profile met the TMF’s objective because the existing volume of 91.4 Mm3 would be treated and would achieve RTR status by 2050, eight years before the end of mine life. However, the AER found that given uncertainties regarding the available technology and the RTR criteria over the medium- to long-term, the revision of the new fluid tailings profile could impact the legacy fluid tailings profile. Consequently, the AER authorized CNUL’s legacy fluid tailings profile only until December 31, 2022.
The solid line in the figure below depicts the authorized legacy fluid tailings profile that CNUL must achieve until December 31, 2022. The dotted line depicts CNUL’s commitment to achieving RTR status for all legacy fluid tailings eight years before the end of mine life.
The AER said that it expects the legacy fluid tailings profile in the amendment application would meet or exceed this commitment.
Thresholds
The volume of accumulated fluid tailings is the primary indicator in the TMF used to manage and decrease liability and environmental risk resulting from the accumulation of fluid tailings. Triggers and a limit (collectively referred to as “thresholds”) are set relative to the fluid tailings profiles. The thresholds ensure that fluid tailings are not accumulating beyond a volume or at a rate that precludes operators from meeting the TMF’s objective. Various management actions are required when thresholds are exceeded.
Three project-specific thresholds are set based on an operator’s fluid tailings profiles in accordance with the TMF and Directive 085:
(a) Profile deviation trigger:
(i) occurs when the volume of fluid tailings is growing 20 percent faster than that approved for the profile;
(ii) additional management action is required when the profile deviation trigger is exceeded;
(iii) is based on when the fluid tailings volume growth is 20 percent higher than that in the approved profile; and
(iv) allows a five-year rolling average to account for year-over-year variability. The profile deviation trigger applies to both legacy fluid tailings and new fluid tailings profiles;
(b) Total volume trigger:
(i) occurs when the volume of fluid tailings has exceeded its approved maximum accumulation and requires additional management action;
(ii) level is based on 100 percent of the greater of the maximum approved fluid tailings volume profile or the end of mine life target (volume of fluid tailings that can achieve RTR state within 10 years after end of mine life and is the equivalent of 5 years, or less, of fluid tailings volume accumulation); and
(iii) applies to the new fluid tailings profile.
(c) Total volume limit:
(i) under the TMF is the volume of fluid tailings above which it presents an unacceptable risk to the environment and potential long-term liability;
(ii) if exceeded will compromise the ability of an operator to have all of their fluid tailings in an acceptable management state (i.e., RTR) within ten years of the end of mine life. Therefore, the most severe management responses are initiated;
(iii) is based on 140 percent of the greater of the maximum approved fluid tailings volume profile or the end of mine life target; and
(iv) applies to the new fluid tailings profile.
To allow for year-over-year variability, the AER set the profile deviation trigger for CNUL as a five-year rolling average of the annual profile deviation, as provided under the TMF and Directive 085. The profile deviation trigger is applicable to both the new fluid tailings and legacy fluid tailings profiles.
The AER considered that its decision to authorize the new fluid tailings profile only until December 31, 2022, affected the approach to set the total volume trigger and total volume limit. The total volume trigger and limit are based on the greater of the maximum approved fluid tailings volume profile or end of mine life target. As there was no end of mine life target authorized, the AER set the total volume trigger at 69 Mm3 and the total volume limit at 97 Mm3.
These thresholds remain in effect beyond December 31, 2022. The thresholds may be revised depending on the AER’s decision on the amendment application.
If any threshold is exceeded, CNUL is required to comply with the management response or action directed by the AER. If CNUL exceeds a threshold after December 31, 2022, Directive 085 provides that “the AER makes the final decision of the fluid tailings volume to be placed in the fluid tailings inventory, any threshold exceedance, and the assigned management level.”
Fluid Tailings Treatment Technology
Technology Selection
Directive 085 requires operators to justify that their selected technologies are the best available for the project. The AER noted that the MRM currently used a combination of composite tailings (“CT”) and thickeners with a codeposition of thickened tailings with tailings solvent recovery unit (“TSRU”) tailings, whole tailings, and coarse sand tailings to form North Pool Deposit (“NPD”) Type deposits. CNUL would discontinue the use of CT by the end of 2018 upon completion of Cell 2.
The AER authorized CNUL to continue to use CT to complete Cell 2 and to use thickeners with a codeposition of the thickened tailings with TSRU tailings, whole tailings and coarse sand tailings to form NPD Type deposits.
CNUL was not authorized to use centrifuge treatment technologies, fluid tailings drying, or atmospheric fines drying (“AFD”) at MRM. CNUL’s TMP did not provide sufficient information for the AER to evaluate the use of these technologies at the MRM, and CNUL did not identify any volume of fluid tailings that will be treated using fluid tailings drying or AFD technologies.
The approval also prohibited placing any water, including industrial wastewater, above treated or untreated tailings for the purpose of creating a water-capped deposit as a closure landscape feature (“water-capped pit lake”).
Because CNUL currently plans to use water-capped pit lakes, CNUL was also required to provide a feasible alternative tailings treatment technology and implementation plan in the amendment application.
The amendment application must:
(a) address the medium- and long-term uncertainties associated with the NPD Type deposit, including environmental risk, segregation, settlement, capping material availability, and deposit performance to support future reclamation activities and achieve stable targeted ecosites that meet the TMF’s outcomes; and
(b) include a plan for additional fluid tailings treatment technology that ensures sufficient treatment capacity.
The AER also required CNUL to report annually on the progress of this ongoing tailings technology selection project.
Ready-to-Reclaim Criteria
Under the TMF and Directive 085, fluid tailings are considered RTR when they have been processed with an accepted technology, placed in their final landscape position, and meet RTR criteria.
RTR criteria are used to track the performance of a tailings deposit toward its ability to be reclaimed as predicted.
RTR criteria are intended to support the objective of reclaiming oil sands mining projects to self-sustaining locally common boreal forest ecosystems that are integrated with the surrounding area and consistent with the values and objectives identified in local, sub-regional and regional plans.
There are two sub-objectives that address different aspects of performance:
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Sub-objective 1: The deposit’s physical properties are on a trajectory to support future stages of activity.
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Sub-objective 2: To minimize the effect the deposit has on the surrounding environment and ensure that it will not compromise the ability to reclaim to a locally common, diverse and self-sustaining ecosystem.
The TMF and Directive 085 allow operators to develop RTR criteria that are suitable for their type of tailings, technology, deposit and future reclamation activities.
Under Directive 085, treated tailings that meet their applicable RTR criteria can be removed from the fluid tailings inventory because they are on a trajectory to meet long-term reclamation outcomes. In circumstances where RTR criteria are no longer met, or there is a deviation from the expected trajectory, CNUL must identify the volume not meeting the RTR criteria and the degree of nonperformance.
Measurement and Averaging
Each treated tailings deposit must be measured to determine if the RTR criteria have been achieved. Directive 085 requires operators to submit a measurement system plan six months from the date of an approved TMP.
CNUL was required to develop a measurement system plan that included the following:
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definitions of parameters for fluid tailings and RTR criteria measurements;
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reference to standards and procedures used to measure fluid tailings and treated tailings and RTR criteria;
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an explanation of and justification for measurement procedures that are unique to CNUL and its plan;
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evidence that the plan will address the measurement outcomes as per section 5 of Directive 085;
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an explanation of how each of the deposit’s RTR criteria will be measured using deposit sampling, calculated, and reported;
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a description of the tailings deposit sampling, measurement, and survey program; and
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justification of how measurement, sampling, and spacing intervals will:
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show the variation of the tailings deposit properties;
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verify that the tailings deposit is achieving RTR criteria; and
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identify if any material in the tailings deposit is not achieving RTR criteria.
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The AER did not accept CNUL’s proposal to use the average solids content by weight of the entire deposit as an RTR criterion since averaging would not provide sufficient information:
(a) to identify variations in tailings characteristics across a deposit; or
(b) to assess risks and liabilities for underperforming treated tailings and the effect on a deposit’s performance toward the targeted ecosites.
The AER found that the averaging process would obscure a meaningful understanding of the deposit volumes that have been treated unsuccessfully or were failing to improve as expected. The AER noted that a deposit might show excellent performance on average while a significant portion of the tailings deposit is underperforming and compromising the ability to reclaim.
The AER, therefore, required CNUL to measure the volume of treated tailings based on deposit sampling. The deposit sampling must be sufficient to identify variability within the entire deposit.
Sub-objective 1: Solids Content
CNUL indicated that solids content by weight was chosen as a sub-objective 1 RTR criteria measure:
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based on historical data;
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as solids content can be used to evaluate the progress of consolidation, the degree of saturation and the readiness for capping of a deposit; and
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given that increasing solids content can be correlated to strength gain in the deposit.
The AER found that solids content alone may not be sufficient to measure a deposit’s performance or its ability to meet future stages of reclamation activity and meet the objectives of the TMF.
The AER, therefore, required CNUL, for each treated tailings deposit, to monitor and report annually, sands-to-fine ratio, effective stress, deposit consolidation, pore water pressure, clay types and percentage, and any other parameters considered relevant by the AER or CNUL.
The AER determined that, given the additional monitoring and reporting required, the use of the solids content by weight of a deposit was an acceptable sub-objective 1 RTR criteria measure until a decision was made on the amendment application.
The amendment application must include updated RTR criteria for all tailings.
Stakeholder and Indigenous Community Engagement
The TMF and Directive 085 describe the importance of transparency, engagement and enhancing stakeholder and indigenous community understanding of fluid tailings management.
The AER noted that, as part of its original approval decision, the AER’s predecessor commended the original applicant, Shell, for its proactive, inclusive and constructive engagement of genuine-interest stakeholders.
To ensure continued transparency, information sharing and involvement in tailings management, the AER required CNUL to engage stakeholders and indigenous communities on tailings management activities undertaken pursuant to the approval.
The AER also required CNUL to:
(a) hold an annual forum with stakeholders and indigenous communities regarding tailings management activities; and
(b) report to the AER annually on its engagement efforts.
Environmental Effects
The TMF’s objective is to minimize fluid tailings accumulation, which may reduce environmental effects such as seepage, occurrences of wildlife contact with tailings ponds, and the tailings footprint.
For previously approved projects, a proposed TMP must:
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be consistent with the previously predicted environmental outcomes or identify any inconsistencies; and
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include mitigation measures and contingency plans, that would minimize the risk of environmental effects over the life of a project.
The AER found that CNUL’s existing surface water and groundwater control measures would adequately manage the environmental effects during the mine’s operating phase. CNUL must operate these measures in accordance with the terms and conditions in its Environmental Protection and Enhancement Act (“EPEA”) approval.
No EPEA approval air emission limits were being amended as a result of the TMP.
There were no changes arising from the TMP that require changes to previously-assessed impacts to surface water and groundwater quality during the mine’s operating phase.
