Since the 1920s, over 400,000 km of petroleum pipelines have been installed in Alberta. Pipeline abandonment is an increasingly relevant issue as the pipeline network ages. The full or partial abandonment of pipeline systems is necessitated by factors such as wind or water erosion issues, pipeline integrity issues, changes in source supply and customer demand, urban development encroachment and regulatory requirements. Pipeline abandonment-in-place is generally the preferred option based on the technical condition and environmental sustainability of the pipeline, however, in some cases pipeline removal or partial removal cannot be avoided. In all cases, the planning process for abandonment includes technical evaluation, risk assessment, environmental assessment, landowner consultation and/or evaluation of future land use. Abandonment plans must also include environmental protection measures to be implemented during the removal of any pipeline segment and consideration of the post-abandonment implications of any pipeline left in place. These measures include topsoil conservation, erosion/sediment control and reclamation. This paper discusses environmental protection measures for pipeline abandonment, using issues faced during abandonment of one of the oldest natural gas pipelines in Alberta as a case study. Challenges faced during this project included gathering of appropriate historical information including leak history and maintenance records, removal of all aboveground facilities, accommodations for future land use plans including road development and measures taken to minimize the risk of the abandoned pipeline becoming a water conduit. In addition, the paper will discuss the extensive planning and construction effort required to undertake pipeline abandonment at several fish-bearing watercourse crossings, where pipeline exposures during high water events necessitated pipeline removal. A primary objective in the planning and the removal of the abandoned pipeline was minimal disturbance of the land.

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