DECOMMISSIONING-1: NEB case study shows abandonment pitfalls

Feb. 12, 2007
Pipeline abandonment must consider environmental remediation beyond simple closure or removal of the line in question.

Pipeline abandonment must consider environmental remediation beyond simple closure or removal of the line in question.

In August and September 1996, Canada’s National Energy Board heard and approved the abandonment of the entirety of Yukon Pipelines Ltd. (YPL), the first and (to date) only large-scale abandonment of an NEB-regulated pipeline. Although the NEB wrote its YPL leave-to-abandon order in 1996, and the majority of the pipeline and related infrastructure were removed soon after, the abandonment is still ongoing.

The leave-to-abandon order will not come into force until YPL demonstrates, to the satisfaction of the Board and in consideration of comments from other stakeholders, that soil and groundwater contamination associated with the pipeline has been successfully remediated.

This article provides an overview of the Board’s regulatory requirements and responsibilities with respect to pipeline abandonment, typical environmental issues associated with pipeline abandonment, and types and examples of pipeline abandonments addressed by the Board to date. Subsequent parts will present a more detailed examination of the YPL pipeline abandonment and associated remediation activity, including a discussion of some of the technical and regulatory challenges associated with the project.

Regulatory requirements

The NEB Act and Canadian Environmental Assessment Act (CEA Act), as well as associated regulations, standards, and guidelines define the NEB’s regulatory requirements and responsibilities with respect to pipeline abandonment. The following summary provides regulatory context for the cases discussed later in the article.

Under paragraph 74(1)(d) of the NEB Act, “A company shall not, without the leave of the Board, ...abandon the operation of a pipeline.” A company, therefore, must apply for and receive a “leave-to-abandon” order from the Board before it can abandon operation of its pipeline facilities.

When this order comes into force, the company’s authorization to operate the pipeline (granted under section 52 or 58 of the NEB Act) is canceled. Consequently, the subject pipeline facilities cease to meet the definition of a pipeline under section 2 of the NEB Act and NEB jurisdiction is terminated.

Sections 19 and 24 of the NEB Act also have important implications with respect to pipeline abandonment. Nothing in the NEB Act grants the Board authority to impose conditions upon a leave-to-abandon order. Subsection 19(1), however, permits the Board to direct that an order shall come into force at a future time or upon satisfaction of conditions imposed by the Board. Section 24 prescribes that any hearing with respect to pipeline abandonment must be public (a public hearing may be either oral or written).

In addition to considering environmental issues in the context of the Canadian public interest in making a decision under paragraph 74(1)(d) of the NEB Act, the Board must first perform an environmental assessment of the pipeline abandonment under sections 5 and 11 of the CEA Act. Typically, the environmental assessment for a pipeline abandonment project takes the form of an environmental screening (per section 18 of the CEA Act). Sections 16 and 18 of the CEA Act provide for public participation and consideration of public comments in the screening of a project. The Board integrates such public involvement into the public hearing process under the NEB Act.

The environmental screening conducted by the Board must consider the environmental effects of the pipeline abandonment project and “measures that are technically and economically feasible and that would mitigate any significant adverse environmental effects of the project” (per section 16 of the CEA Act).

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If the Board determines, pursuant to paragraph 20(1)(a) of the CEA Act, that, taking into account appropriate mitigation measures, the abandonment is not likely to cause significant adverse environmental effects, the Board may then issue its leave-to-abandon order. In doing so, the Board has the responsibility, per subsection 20(2) of the CEA Act, to ensure that mitigation measures taken into account in its decision are then implemented.

The leave-to-abandon order, however, terminates the Board’s jurisdiction and consequently its ability to ensure implementation of mitigation measures. In order to nonetheless meet its obligations under the CEA Act, the Board may use subsection 19(1) of the NEB Act to delay official leave to abandon until the physical abandonment activities have been completed and conditions with respect to environmental mitigation have been fulfilled.

According to subsection 15(3) of the CEA Act, for any physical work requiring an environmental assessment (for example, pipeline construction), the Board must consider every undertaking likely to be carried out in relation to that work, including abandonment.

In practice, because abandonment of most pipelines occurs in the distant future, this consideration typically takes the form of a standardized statement that “any environmental effects associated with the abandonment phase are likely to be similar to those caused by the construction phase. Pursuant to the NEB Act, an application will be required to abandon the facility, at which time the environmental effects will be assessed by the NEB.”1


Onshore Pipeline Regulations, 1999 (OPR-99) also governs NEB-regulated pipelines under the NEB Act. These regulations are goal-oriented (a blend of performance-based and prescription-based) and contain many provisions that apply to the full life of a pipeline, including abandonment. Section 1 defines abandon as “to remove permanently from service” and Section 50 states that an application pursuant to paragraph 74(1)(d) of the NEB Act “shall include the rationale for the abandonment and the measures to be employed in the abandonment.”

CSA Standard Z662-03, Oil and Gas Pipeline Systems (CSA Z662) applies to NEB-regulated pipelines transporting liquid or gaseous hydrocarbons. CSA Z662 defines piping, abandoned, as “piping that is removed from service and not maintained for later return to service” and includes more prescriptive requirements for pipeline abandonment than OPR-99.

Based on a 1996 discussion paper, Clause 10.14.1 specifies “the decision to abandon a section of piping, in place or through removal, shall be made on the basis of an assessment that includes consideration of current and future land use and the potential for safety hazards and environmental damage to be created by ground subsidence, soil contamination, groundwater contamination, erosion, and the creation of water conduits.” Clauses 10.14.2 and provide further details pertaining to the physical abandonment of the piping.2

Guidance Notes for the Onshore Pipeline Regulations, 1999, includes guidance with respect to regulatory requirements for pipeline abandonment.

The NEB Filing Manual includes guidance with respect to information to be included in abandonment applications in order for the NEB to make its decisions under the NEB Act and CEA Act.

The NEB continues to work on revisions to OPR-99 to distinguish between pipeline abandonment (permanent cessation of operation that results in discontinuance of service) and decommissioning (like “abandonment” but without discontinuance of service to end users).3-5 These amendments would provide regulatory clarity for projects such as diversion, replacement, or discontinued use of an old pipeline segment where a new or existing segment of pipeline would continue to provide the same service.

Companies currently apply to undertake such projects under Section 52, 58, or 74 of the NEB Act, none of which adequately accommodate these applications.3 The revised regulations would ensure that applications to decommission a pipeline receive examination and regulatory oversight of technical and environmental issues similar to those for abandonment, but without requiring the regulatory process necessary to address the effects of abandonment on end users.

Environmental effects

Pipeline abandonment can involve removal of the pipeline or abandonment in place, each with characteristic environmental effects discussed in detail in the Pipeline Abandonment Steering Committee’s 1996 discussion paper on pipeline abandonment technical and environmental issues.2

Pipeline abandonment by removal may be desirable when abandoning the pipeline in place could obstruct future land use or development, or result in a safety hazard. Pipeline abandonment in place may be desirable in areas sensitive to land disturbance such as environmentally sensitive areas, unstable or highly erodible areas, or crossings with water bodies, roads, railways or other pipelines. Large-scale pipeline abandonments typically use a combination of both options, with some segments abandoned in place and others removed depending on site-specific requirements.

Environmental effects of pipeline removal are similar to those of pipeline construction. Typical considerations include access, protection of cultural features and environmentally sensitive areas, topsoil conservation, erosion prevention, vegetation management, contingency planning, surface reclamation, and post-construction monitoring.

Abandonment in place still entails some ground disturbance, with similar environmental considerations but on a smaller scale. Whichever abandonment option an operator chooses, attention should be given to additional issues of ground subsidence, drainage, and contamination of soil, groundwater, and surface water.

Regulations state that where pipelines are abandoned in place “ground subsidence would be negligible for pipelines up to 323.9 mm in diameter,” but should be assessed on a site-specific basis for larger pipelines.2 The settling of soil disturbed by pipeline removal may also cause subsidence. Ground subsidence may channel surface runoff, resulting in topsoil loss, erosion, and siltation of water bodies.

The creation of water conduits associated with abandoned pipelines can lead to drainage of water bodies, flooding of previously dry low areas, and transport of contaminants. This problem is typically associated with corrosion of pipelines abandoned in place, allowing groundwater to enter, exit, and flow though the abandoned pipe, but preferential groundwater flow through uncompacted trench material following pipeline removal can create similar problems.

Typical mitigation measures for these subsidence and drainage issues include strategic placement of plugs and grouting, compaction of disturbed subsoil, and appropriate pipeline cleaning prior to abandonment in place.

Appropriate pipeline cleaning reduces residual contamination regardless of the abandonment option selected. If the operator chooses to remove the pipeline, it should first be emptied and cleaned sufficiently to prevent the release of contaminants when cutting the pipe into segments. If the pipeline is to be abandoned in place, cleaning should be sufficient to prevent contamination of the surrounding environment when the pipe corrodes and becomes a water conduit.

The other contamination issue presenting a wildcard regarding the time and money required for pipeline abandonment and reclamation is historical contamination from operational releases, leaks, and spills. Although abandonment does not cause historical contamination, it must be remediated for the protection of human and environmental health before the affected land is released for nonpipeline use.

As is the case for other pipeline abandonment issues, operators must seek meaningful input from stakeholders, including pertinent regulatory bodies, landowners, and land managers when addressing historical contamination. Landowner concerns may include health effects of residual hydrocarbon concentrations, effect on future land use, and effect on property value.

NEB decisions

Decisions made by the NEB during the past 15 years illustrate how the Board’s treatment of abandonment has evolved and provide context for the YPL abandonment.

Before 1996, minor abandonment applications considered by the Board included 3 Trans-Northern Pipelines Inc. (TNPI) projects in 1993 (Table 1). NEB did not hold hearings in these cases and the end users had no further need for the facilities.

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Environmental screenings considered factors including soil and groundwater contamination and revegetation. The NEB orders granted TNPI immediate leave to abandon the facilities and then (except for MO-22-93) added conditions pertaining to the abandonment. These conditions required TNPI to conduct environmental site assessments (ESAs) for contamination and undertake remediation if required.

The then-current federal environmental quality guidelines, as adopted by the Canadian Council of Ministers of the Environment (CCME), defined contamination.6-9

The 1996 hearing scrutinized pipeline abandonment much more closely with respect to the abandonment in place of the last 21.9 km of a pipeline owned by Manito. Because this segment was the only portion of the pipeline crossing a provincial border, the pipeline abandonment order (MO-5-96, pursuant to Hearing Order MH-1-96) resulted not only in the termination of the Board’s jurisdiction over the abandoned pipeline segment, but in the termination of the Board’s jurisdiction over the entirety of the remaining pipeline (located wholly in Saskatchewan).

Debate surrounding the pipeline abandonment was based primarily on economics and questions of jurisdiction, leading to intense discussion regarding when and how the Board’s jurisdiction would terminate and what government body would be responsible for regulatory oversight of contaminant remediation and ongoing environmental protection. Although Manito proposed remediation activities at some future date in conjunction with abandonment and remediation of associated production facilities under provincial regulation, the Board ordered Manito to remediate contaminated soils prior to “leave to abandon” the facilities.

Then-current CCME and provincial guidelines and background concentrations defined contamination. Other environmental issues addressed by Manito and considered by the Board included pipeline cleaning, creation of groundwater conduits, removal of surface facilities, surface water control, and waste management.

In contrast to the TNPI abandonment orders, the Board stipulated that leave-to-abandon would not come into force until certain conditions (including contaminant remediation) were met, placing conditions on the timing of the order coming into effect (per subsection 19(1) of the NEB Act) instead of on the abandonment itself (per paragraph 74(1)(d) of the NEB Act).10 11

In November 1997, once satisfied that Manito had met all the conditions of leave-to-abandon, including remediation of contamination attributed to operation of the pipeline, the Board declared the abandonment complete.12 This case set the stage for the YPL abandonment.

Following the YPL abandonment, cases considered by the Board have dealt primarily with projects that would be considered decommissionings under proposed OPR-99 revisions. For example, in 2002-03, TNPI applied under paragraph 74(1)(d) of the NEB Act to replace or re-route several pipeline segments as part of larger facilities construction applications. The Board noted that there would be no discontinuance of service as a result of these activities and decided that the activities could thus be addressed under section 52 of the NEB Act in conjunction with the overall construction activities for which TNPI had applied.

Abandonment, however, still guided consideration of issues pertaining to the environment and the termination of NEB jurisdiction. Environmental issues considered included historical soil and groundwater contamination and potential corrosion-created water conduits, which would then leach pipe materials into the groundwater. The NEB ordered TNPI to remediate any detected contamination to meet both federal and provincial guidelines.13-16

By contrast, in 2004, the Board issued Enbridge Pipelines Inc. an abandonment order (XO-E101-22-2004) pursuant to paragraph 74(1)(d) of the NEB Act for an old line segment that Enbridge was going to remove with no change in service. No hearing was conducted. Similar to the 1993 TNPI orders, leave-to-abandon came into force without delay and conditions were attached to the abandonment itself. Environmental issues considered included possible historical soil and groundwater contamination, potential naturally occurring radioactive materials (NORMs), topsoil conservation, and reclamation of disturbed areas.

The NEB ordered Enbridge to report any contamination encountered and how it would be remediated. Contamination was not defined in terms of provincial or federal guidelines.17

The proposed decommissioning revisions to OPR-99 would provide greater regulatory clarity and consistency regarding cases such as these.


The author acknowledges her colleagues at the National Energy Board for their assistance with management and review of this file and preparation of this article. She also thanks Dan Bulat of Envirotech Engineering for assistance with the review of this article.


  1. National Energy Board, “Environmental Screening Report [for Profico Energy Management Ltd. Construction of a 2.5 km Inter-Provincial Pipeline],”, August 2005.
  2. Pipeline Abandonment Steering Committee (Technical and Environmental Subcommittees), “Pipeline Abandonment: A Discussion Paper on Technical and Environmental Issues,”, November 1996.
  3. National Energy Board, “Proposed Amendment to the Onshore Pipeline Regulations, 1999-Decommissioning of Pipelines and Related Facilities,”, February 2003.
  4. National Energy Board, “Decommissioning of Pipelines and Related Facilities, Proposed Amendments to the Onshore Pipeline Regulations, 1999 and National Energy Board Processing Plant Regulations, Proposed Decommissioning Exemption Order,”, October 2003.
  5. National Energy Board, “National Energy Board Workshop 2003: NEB Workshop Proceedings,”, pp. 5-7, 60, 2004.
  6. National Energy Board, “Environmental Screening Document [for File No: 3400-T2-19, Trans-Northern Pipelines Inc., application to abandon Port Hope Meter Station, Prescott Meter Station and Prescott Lateral],” September 1993.
  7. National Energy Board, “Environmental Screening Document [for File No: 3400-T002-21, Trans-Northern Pipelines Inc., two projects on pipeline leased from Sun-Canadian Pipe Line Company Limited],” September 1993.
  8. National Energy Board, “Environmental Screening Document [for File No: 3400-T002-22, Trans-Northern Pipelines Inc. abandonment of Markham Meter station and Lateral and Hamilton Meter Station and Lateral],” November 1993.
  9. National Energy Board, “Environmental Screening Report [for Trans-Northern Pipelines Inc., or the Company, application dated Sept. 2, 1996, for the abandonment of the Hamilton Lateral and Hamilton Meter Station in the Province of Ontario],” March 1996.
  1. National Energy Board, “Environmental Screening Report [for Manito Pipelines Ltd., application dated Jan. 31, 1996, by Murphy Oil Co. Ltd. on behalf of Manito for the abandonment of the operation of the Blackfoot-Dulwich Pipeline System (the pipeline system), located in the Provinces of Alberta and Saskatchewan],” June 1996.
  2. National Energy Board, “Reasons for Decision, Manito Pipelines Ltd., MH-1-96, Facilities Abandonment,”, July 1996.
  3. National Energy Board, “Manito Pipeline Ltd., Abandonment of Blackfoot to Dulwich Pipeline as set out in Board Order Mo-5-96,” November 1997.
  4. National Energy Board, “National Energy Board Environmental Screening Report, Trans-Northern Pipelines Inc. Capacity Expansion and Line Reversal, Montréal, Quebec to Mississauga, Ontario, File 3200-T002-1, OH-1-2003,”, July 2003.
  5. National Energy Board, “Reasons for Decision, Trans-Northern Pipelines Inc., OH-1-2003, Facilities,”, July 2003.
  6. National Energy Board, “Environmental Screening Report [for Trans-Northern Pipelines Inc. Relocation of a Segment of Pipeline and Lowering of two Segments of Pipeline in the City of Hamilton, Ontario],”, November 2003.
  7. National Energy Board, “Reasons for Decision, Trans-Northern Pipelines Inc., OHW-1-2003, Facilities,”, November 2003.
  8. National Energy Board, “Environmental Screening Report [for Enbridge Pipelines Inc. Removal of 3.2 km of pipeline that has been deactivated since 1987],”, October 2004.

Based on a presentation to the ASME International Pipeline Conference, Calgary, Sept. 25-29, 2006.

The author

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Katherine E. Roblin ([email protected]) is an environmental specialist at the National Energy Board, Calgary. She has also served as an environmental engineer at O’Connor Associates Environmental Inc. She holds a BS in engineering (1996) from Queen’s University at Kingston, Ont. She is a member of the Association of Professional Engineers, Geologists, and Geophysicists of Alberta (APEGGA) and the Canadian Land Reclamation Association.