This Technical Guidance Document is intended to provide preliminary design and management recommendations for End Pit Lakes (EPLs) in the Athabasca oil sands area. EPLs are an integral component in the management, operation and final reclamation landscape of oil sands development. This Technical Guidance Document will provide managers and oil sands industry representatives with guidelines to help resolve the optimal design and EPL parameters for their respective projects. This Technical Guidance Document is a living document and is meant to be flexible and responsive in its content. The first edition is based on knowledge gathered to date (2007) and will be updated as new information and research results become available. The second edition is expected in about 5 years, or in 2012, and should expand upon the current knowledge base, research results and recommendations for EPL design and management.
An EPL will be established in a mined-out pit of an excavated area. It will consist of a bottom substrate capped with water; soft tailings or other process-related materials may be placed on top of the bottom substrate. An EPL will need to be controlled, managed and monitored throughout much of its initial filling and during discharge to downstream aquatic environments. Ultimately, the EPL will become a biologically active, self-sustaining and functional ecosystem.
There are uncertainties regarding the construction, maintenance and final success of EPLs. The development of EPLs as a reclamation tool for process-affected waters raises issues of concerns for regional stakeholders. This document summarizes the perspectives and concerns of regulators, environmental and community groups, Aboriginals and the oil sands industry itself. Applicable government legislation, guidelines and policies are summarized.
Historical data are insufficient to determine a realistic outcome of the final features of EPLs. Modelling and relevant background studies have been the basis of research, but a fully realized EPL has yet to be constructed. Issues to be considered during the development, implementation and management of EPLs include the design, amounts and inflow/outflow rates of reclamation and natural waters, water quality, stratification and the toxicity and/or concentrations of compounds. EPLs will need to meet water quality guidelines prior to release to adjacent environments. Issues also include potential impacts to aquatic life, the bioaccumulation of compounds within the food web and the development and sustainability of the ecosystem.
Ongoing research, monitoring and new technologies will fill in these gaps. This document summarizes the results of historic research on EPLs. Current research directed by the CEMA EPLSG is also summarized. To date, the EPLSG research has focused on the selection and refinement of models best suited to predicting the potential for meromixis in EPLs. Nomographs have been developed that predict the stratification behaviour of lakes over time under various salinity, depth and size features. Future research will focus on further improvement of meromictic modelling, the influence of water quality on meromixis and biophysical modelling.
Key physical, chemical and biological components to be considered during the design and management of EPLs are described. Recommended design specifications to attain the goal or desired outcome of these components are also compiled in table format. Monitoring requirements including key parameters and frequency are included. Adaptive management is recommended as a method of incorporating flexibility and responsiveness to ongoing management challenges. The process of designing, managing and operating an EPL is summarized, as is the process for obtaining a reclamation certificate.