Cumulative Effects Assessment Practitioners' Guide

Cold Lake Oil Sands Project: Case Study Highlights

VECs: Air quality, water quality, water quantity, fish, vegetation, moose, black bear, lynx, fisher

Issues: Changes to air quality, changes to surface and groundwater water quality, decreases in surface water levels, loss of wildlife habitat, reduced opportunities for fishing and other resource harvesting, increased road access

Approaches: Focussed Environmental Assessment Process provided an overall framework; Impact Models provided a structured methodological approach; quantitative GIS-based or other modelling provided numerical analysis; qualitative discussion based on quantitative results and professional judgment

Lessons learned: Advantages of blending EIA and CEA approaches, benefits of Impact Model approach; difficulties in obtaining information about other projects


Imperial Oil Resources Limited (Imperial Oil) proposed to expand its operations within its Cold Lake lease in north-central Alberta (IORL 1997a). This oil sands in-situ development, known as the Cold Lake Expansion Project, will expand the existing Cold Lake operations by the development of a central plant and addition of wells. Production is expected to increase from approximately 14,900 m 3/d to more than 20,000 m 3/d within a few years of operation. Approximately 2500 wells are currently operating within the Cold Lake Development Area.

The Cold Lake facility, the second largest producer of oil in Canada, extracts oil from sand deposits containing bitumen (a heavy oil). These deposits are located more than 400 m below the earth's surface, too deep for recovery by surface (open-pit) mining. Imperial Oil therefore developed cyclic steam stimulation, a thermal recovery process that injects steam at high pressure and temperature into the bitumen reservoir. The process consists of three steps (steaming, soaking and production) that is repeated until depletion of the bitumen reservoir.

Many pads, each containing a cluster of vertical and directional drilled wells (approximately 20 to 30) are used to access the bitumen-producing reservoir. Above-ground pipelines serve multiple pads, delivering steam to the pads and returning produced fluids to the central plant.

Assessment Approach

Imperial Oil was required to submit an EIA according to the Terms of Reference issued by Alberta Environmental Protection. The EIA was to identify direct project effects and cumulative regional impacts of the project. The objectives of the CEA component were to evaluate project-specific impacts in a regional context, taking into consideration other activities and projects that currently exist in the project region or projects that are reasonably foreseeable (i.e., have been approved, or are under approval). The Focused Environmental Assessment Process (Kennedy and Ross 1992) formed the basis of both the EIA and CEA. This approach included the use of a series of three workshops (issues scoping, assessment and mitigation) that provided a forum for practitioners to address various assessment issues. The Process also made use of Impact Models to describe important cause-effect relationships between the project and its surrounding environment.


Nine major environmental resource components were examined: air systems, surface water quantity, surface water quality, groundwater, aquatic resources, soils and terrain, vegetation, wildlife and resource use. A unique local and regional study area was identified for each component. In some cases, areas were the same for more than one component. Generally, the CEAs spatial bounds were based on existing jurisdictional boundaries or boundaries of the watershed surrounding the project. Effects were examined at local, combined (i.e., all project components) and regional scales.

Three temporal bounds were identified: 1) "Past" to represent regional conditions (i.e., pre-1979) prior to the proposed major heavy-oil development in the region; 2) "Existing" that included Imperial Oil's current operations and other existing projects in the region (e.g., other oil sands projects, forestry); and 3) "Reasonably Foreseeable" that included all future projects with regulatory approval or that were under an approval process.


Project effects were assessed at two scales: 1) combined effects of various activities directly associated with the project such as the pads, roads, and processing facilities; and 2) cumulative regional effects of the project with all other existing and reasonably foreseeable projects beyond the proposed expansion area (IORL 1997b).

The CEA relied on the results from a total of 35 Impact Models completed in the EIA (IORL 1997b). The models assessed effects on each of the nine environmental components. These models generally dealt with local effects; however, some models had regional implications "built-in" due to the wide extent of the effects. In these cases, conclusions reached from the models served as the basis for further assessment at a regional scale in the CEA (which consisted of a chapter in one of the volumes of the application submission). For some of these, the Impact Model itself constituted a substantial portion of the assessment approach for cumulative effects. Due to the close cause-effect relationships between different environmental components (e.g., water quality and aquatic resources), many Impact Models were "linked" together so that the output (i.e., results) from one model provided input into another.

The assessment of cumulative effects involved various degrees of quantitative (i.e., numerical) analysis and qualitative discussion. Qualitative analysis was conducted if a quantitative technique was not available or if a qualitative discussion was adequate. In all cases, interactions with various other projects were considered if the results of the Impact Models indicated a possibility of other than local effects. Temporal development scenarios were explicitly used in the assessment of effects on wildlife (the table "Summary of CEA Approaches" summarizes approaches used for each environmental component).

Lessons Learned

  • The use of a consistent assessment approach (i.e., Focussed Environmental Assessment) was beneficial, as the assessors found the CEA to be simply an extension of results from the EIA. Also, use of the same environmental components in the EIA and CEA and consistent approaches for determining impact areas and significance improved the communication of assessment results for decision-makers.
  • The identification and characterization of other projects in the CEA regional study area presented some challenges, partially overcome by including only projects with regulatory approval or under regulatory review.
  • The use of threshold values for environmental components presented challenges. For the physical components (i.e., air, water, soil) it was possible to use accepted guidelines and standards and, with appropriate assumptions, to simply extend values to the regional scale. For biological components (i.e., aquatic resources, vegetation, wildlife) it was not as straight forward, as the implications of project effects were more complicated owing to synergistic effects and to effects that are not scientifically understood or easily interpreted.
Summary of CEA Approaches
Environmental ComponentCEA Approach
AirSix Impact Models were developed. NOx and SO2 concentrations were calculated with a numerical air quality model as required by Alberta Environmental Protection and compared to provincial air quality thresholds within the airshed surrounding the project.
Surface Water QuantityThree Impact Models were developed. Water use volumes and project sources were compared with volumes from other projects.
Surface Water QualityFour Impact Models were developed. Key water quality parameters as defined by provincial guidelines were assessed.
GroundwaterThree Impact Models were developed. Contributions to water withdrawals, effects on water balance, and effects on water quality were assessed.
Aquatic ResourcesTwo Impact Models were developed. Qualitative discussion was used based on results of water quality and quantity assessments, regional workforce changes, and results of assessment of effects on various indicator fish species.
Soils and TerrainFive Impact Models were developed. Cumulative effects were limited due to the very local nature of impacts and use of mitigation for provincial reclamation certification.
VegetationThree Impact Models were developed. The area of land cleared was quantitatively determined in a GIS for each of the 20 vegetation ecosites within the regional study area.
WildlifeFour Impact Models were developed. Total habitat lost was quantitatively determined and implications on wildlife qualitatively discussed; changes in access density was quantitatively determined and implications on wildlife qualitatively discussed; changes in habitat suitability for four indicator species (moose, black bear, lynx and fisher) was quantitatively determined (with a GIS) and compared between three development scenarios.
Resource UseFive Impact Models were developed. Qualitative discussion was used, based on results of impact models for all environmental components, focussing on implications of influences of regional "agents of change" (e.g., road proliferation, human population growth).
  • The CEA for resource use is complex due to the often broad or subjective nature of the VECs. It was helpful to assign qualitative criteria for each resource use and provide detailed qualitative discussion based as much as possible on the baseline data and results from other Impact Models.
  • The proponent was not in a position to reasonably address regional planning issues. Regional issues were discussed in the CEA with a recommended action plan for review by decision-makers (e.g., a regional scale environmental monitoring program).
  • The integration of results from public consultation is a useful tool in determining relevant regional issues to be included in the CEA. It is important to ask questions about cumulative effects concerns during public consultation.
  • The CEAs methodological approach included a judicious blend of quantitative and qualitative based assessment. In all cases, the Impact Models provided direction in the assessment for each environmental component. Professional judgement, as is typically the case in EIA practice, was often used to provide the final interpretation of the assessment results regarding overall regional and long-term implications on VECs. Extensive use of quantitative analysis (i.e., air models, water volumes, spatial changes to vegetation and habitat) considerably improved the final conclusions made by assessment practitioners.