The Pipeline Abandonment Research Steering Committee (PARSC) through the Petroleum Technology Alliance of Canada commissioned CH2M HILL Energy Canada, Ltd. (CH2M), Decom Consulting Ltd., and Allnorth Consultants Limited (Allnorth) to conduct a review of a previous pipeline abandonment program, which involved a surface assessment of three 34-inch-diameter (836.6-millimetre outside diameter) pipeline segments of the Enbridge Pipelines Inc. (Enbridge) Line 3 pipeline (the Project), abandoned between 1978 and 1980. The pipeline segments are colocated with other operating pipelines within the Enbridge Mainline right-of-way (ROW), to the immediate east of the City of Edmonton. The pipeline segments were both areas where the abandoned pipeline segment was removed and where the pipeline was abandoned in place. Segments of the pipeline that were abandoned in place were capped, filled with inert gas pressure, and had cathodic protection maintained in accordance with Section 121 of the Oil and Pipeline Regulations, SOR/78-746, September 28, 1978.
The objective of the Project is to review the condition of a medium-diameter pipeline that was abandoned more than 10 years ago, and to evaluate the outcomes achieved by the pipeline abandonment program. To evaluate the outcomes of the pipeline abandonment program, the following tasks were completed:
- Review of the pipeline abandonment methodologies that were implemented at the time of pipeline abandonment
- A field surface assessment, to determine if there was evidence of effects or potential effects of pipeline abandonment in place, as currently understood by the industry
- Identification of any effects of pipeline abandonment, to determine if there was evidence outside of the current industry understanding of the risks of pipeline abandonment
- Identification of areas along the abandoned pipeline segments where subsurface testing could be conducted to further confirm the presence or absence of those potential effects
The previously identified potential effects of pipeline abandonment in place include:
- Ground subsidence and frost heave
- Soil and groundwater contamination
- Subsidence at road, railway, and utility crossings
- Watercourse and wetland crossings
- Creation of water conduits
The abandoned pipeline segments were assessed using ground-based field studies to determine if there was surficial evidence of the potential environmental effects of pipeline abandonment and to suggest locations where further assessment (that is, subsurface investigation) is recommended to visualize the pipe and surrounding soil for the potential effects described in this report.