The Petroleum Technology Alliance Canada retained Amec Foster Wheeler Environment & Infrastructure to conduct a Water Conduit Effect in Abandoned Pipelines study that included a literature review (Task 1), scenario identification (Task 2) and identification of potential mitigations (Task 3).
Water conduits are defined by the Pipeline Abandonment Steering Committee of the National Energy Board as: “A channel for conveying water. In the context of pipeline abandonment or decommissioning, refers to a pipeline that has become corroded and perforated and transports ground or surface water to a different location.”
A total of seventy-nine (79) sources of possible information were reviewed for real world examples and theoretical scenarios concerning water conduits in abandoned pipelines. No historical instances of water conduit formation in pipelines were found in the literature search, but research indicated that it remains a potential concern for pipeline abandonment. While several theoretical water conduit scenarios have been proposed, an understanding of the requisite conditions for water conduit formation in real-life applications has yet to be adequately established. Based on our understanding of the water conduit effect, the most likely scenarios involve: Contaminated Sites, Inclines, Recharging Water Bodies (rivers, lakes, oceans), and Small Water Body (wetlands, sloughs). The above four scenarios, are described and specific mitigation measures and management options to address them are made.
Amec Foster Wheeler notes that, given the predicted corrosion of pipelines is a long term process, there is considerable time to develop a more complete understanding of water conduits before implementing mitigation. Some studies have taken the approach that the risks associated with water conduit formation should be addressed at the time of abandonment (i.e. mitigation and management practices are carried out at that time); however, it may also be appropriate to assign a liability based on best mitigation practices like those in the table, but delay implementation of mitigations measures until a better understanding of water conduits formation is acquired.