http://www.neb-one.gc.ca/clf-nsi/rsftyndthnvrnmnt/sfty/nvstgtnrprt/trnsmntnsmstnk121lk/trnsmntnsmstnk121lk-eng.pdf
Investigation under the National Energy Board Act In the Matter of 2012-01-24 Trans Mountain Pipeline ULC Sumas Tank 121 Leak [PDF 1060 KB]
FAQs – Final Investigation Report: Trans Mountain Pipeline ULC Sumas Tank 121 Leak
November, 2012
Copyright/Permission to Reproduce
Table of Contents
List of Appendices
List of Abbreviations and Definitions
1. Summary
2. Scope and Objectives of Investigation Under the National Energy Board Act (NEB Act)
3. Factual Information
3.1 Incident Description
4. Results of the Investigation Under the NEB Act
4.1 Failure Mechanism of the Tank Roof Drain System
Chapter 1 – Summary
On 24 January 2012, a release of 90 m³ of crude oil into the secondary containment of Tank 121 at Trans Mountain Pipeline ULCs (TMPU) Sumas Terminal in Abbotsford, BC occurred. The investigation revealed that the leak occurred after a gasket in a flange pair of the Tank 121 roof drain system failed under excessive pressure caused by water freezing in the roof drain system.
Although TMPU had a new procedure requiring the tank roof drain valve to normally be closed, the tank roof drain valve was open at the time of the incident. This was a contributing factor to the incident. The investigation found that TMPUs management of the procedural change to the normal drain valve position was inadequate.
The leak was detected later than it should have been. This can be attributed to the fact that the Control Centre Operator (CCO) did not follow TMPUs procedures on two occasions when setting and responding to the alarms and failed to recognize the leak situation. The investigation found that there were improper alarm settings in TMPUs new Supervisory Control and Data Acquisition (SCADA) system and this may have contributed to the CCOs inadequate response to the alarms.
The safety of Canadians and protection of the environment are the National Energy Boards (NEB or Board) top priorities. The Board requires pipeline companies to anticipate, prevent, manage and mitigate potentially dangerous conditions associated with their pipelines. TMPU has identified corrective actions to address all of the findings of cause and contributing factors identified in this investigation report. The Board is satisfied that these actions are appropriate to prevent the occurrence of similar incidents in the future.