CEMA Delivers Oilsands Mine End Pit Lake Guidance Document

FORT MCMURRAY, AB, Oct. 4, 2012 /CNW/ - The Cumulative Environmental Management Association (CEMA) has approved and forwarded an End Pit Lakes Guidance Document to the Government of Alberta for its consideration. The living document took several years to complete and provides a 100-year operational plan for the design and creation of the 30 proposed End Pit Lakes in the mineable Athabasca oilsands region.

CEMA defines an oilsands End Pit Lake (EPL) as:

"An engineered water body, located below grade in an oil sands post-mining pit. It may contain oil sands by-product material and will receive surface and groundwater from surrounding reclaimed and undisturbed landscapes. EPLs will be permanent features in the final reclaimed landscape, discharging water to the downstream environment.

If oilsands operators can successfully demonstrate the effectiveness of EPLs as a reclamation tool, the new lakes could also serve as a permanent alternative to the temporary tailings ponds that now store by-products of the oilsands extraction process. The Guidance Document, which was written and peer reviewed by an international team of scientists and engineers, draws on the best available science to help operators test the concept.

"CEMA doesn't support or oppose the creation of End Pit Lakes in the closure plans of oilsands mine operators with leases in the Wood Buffalo region. But this document is currently the only one available to the planners and engineers responsible for reclaiming oilsands leases," said CEMA Executive Director Glen Semenchuk. "The work by the End Pit Lake Task Group and its consultants is world-class and peer-reviewed."

A multi-stakeholder, non-profit society CEMA is a key advisor to the provincial and federal governments and is committed to respectful, inclusive dialogue and collaboration. It makes recommendations to government on the management of cumulative environmental effects of regional development on air, land, water and biodiversity. CEMA has produced similar guidance documents for wetlands, soils, revegetation, and riparian areas.

To view the End Pit Lake Document or for more information visit www.cemaonline.ca.

BACKGROUND

No oilsands end pit lake (EPL) currently exists, but about 29 are proposed within the mineable oilsands region. The document presents the scientific and engineering expertise to guide all reclamation activities associated with EPL design and construction. This is a technical guidance document, one that provides the information, direction, and the advice that the planners and engineers who will be responsible for turning about 29 pits into functioning, healthy aquatic ecosystems will require to carry out those activities.

The current objectives for EPLs in the Athabasca oilsands were established by stakeholders in the region who agreed to participate in the information-gathering process: government agencies, Aboriginal and non-governmental organizations, and industry. It does not represent the views of all potential stakeholders, as a comprehensive survey or formal consultative process was beyond the project's mandate.

EPLs may or may not contain tailings associated with mining. In general, two types of EPLs are anticipated for oilsands mine sites:

EPLs with tailings storage: In this scenario, soft tailings such as fluid fine tailings or thickened tailings are capped with a layer of freshwater. Inputs to the lake include surface runoff, precipitation, groundwater seepage, and consolidation waters from tailings deposits. Tailings become denser over time and release pore water to the water cap. Process-related materials that may be placed in the mined-out pits includes tailings deposits, tailings sand, lean oilsands, overburden, petroleum coke and process-affected waters that remain at the end of mine operations.

EPLs without tailings storage: The excavated mined-out pit is allowed to fill with surface runoff and groundwater once mining and dewatering activities cease. The list of design and management considerations of EPLs that do not contain tailings is significantly shorter than those that do store mine tailings.

Returning mineable oilsands developments in the Athabasca oilsands region to a state functionally equivalent to the natural conditions that characterize the boreal forest of northern Alberta will involve a sophisticated suite of tools, techniques, and expertise. The end pit lake is an integral element of this task.

Reclamation of the pit that remains at the end of a mine's life, and its transformation into a sustainable lakes, is a developing technology. As a result, industry can draw on experiences from pit lakes created in other mining industries along with current research and literature reviews conducted within the region. Such experiences include Syncrude Canada's Base Mine Lake (BML) demonstration lake and test wetlands and CEMA's in-lake dynamics and water quality modeling and geotechnical stability analysis of EPL shorelines. The oilsands can also draw on experience from pit lakes created by other industries, such as Teck Coal's Sphinx Lake in Sparwood, British Columbia.

The permanent placement of fine tailings in EPLs is approved for many oilsands mines, subject to demonstration, based on previous Energy and Utilities Board Decisions.

EPLs will not be constructed in the undisturbed landscapes.

Independent experts reviewed every chapter of this document. But the science of EPLs and the regulations that govern their construction and management will continue to evolve. This document is intended to provide a base of knowledge, and direction, for EPL design and construction.

SOURCE: Cumulative Environmental Management Association

Corey Hobbs
CEMA Communications
780-881-4943
[email protected]