Trans Mountain has completed a number of expansion projects since the original pipeline became operational in 1953. As a result, about 28 per cent of the 1,150-km pipeline system between Strathcona County, Alberta, and Burnaby, BC is already twinned.

The twinned sections have an active pipeline and a deactivated segment of pipeline. The deactivated segments are 24 inch pipe and are monitored and maintained, in anticipation of future use.

To complete the full twinning of the pipeline system, we will reactivate two pipeline segments that have been maintained in a deactivated state for the Trans Mountain Expansion.

We are bringing these inactive pipeline segments back into service:

  • Hinton, Alberta to Hargreaves, BC: approximately 150 km
  • Darfield to Black Pines, BC: approximately 42 km

Maintenance and Reactivation of Existing Line

The inactive 24-inch segments of the Trans Mountain Pipeline and any other pipe segments considered inactive are maintained as part of our ongoing Integrity Management Program.

This means the inactive segments are continuously protected against external corrosion with the same cathodic protection system as the active pipeline segments. The inactive segments are filled with nitrogen to maintain an inert environment and protect against internal corrosion.  The inactive segments are also protected through the Ground Disturbance program, with response to One Calls and internal permitting requirements to protect the pipe against third-party line strikes.

One of the differences between active and inactive pipeline segments is In-Line Inspection (ILI) tools are not run through inactive pipe as they are not in operation and don’t have any petroleum products within. While the pipeline is inactive, there is no potential for spills, and inspections and repairs are not required.


Before inactive pipeline segments are put back into service, we perform a number of steps to check the pipeline’s integrity. These measures include, however are not limited to:

  • Run ILI tools through the inactive pipe to inspect for any possible integrity hazards (such as metal loss, mechanical damage and cracking); up to four ILI tools will be passed through each section
  • Repair any defects identified by the ILI tools, just as we would on an active pipe segment
  • Perform a hydrostatic pressure test (test with water) to confirm the pipeline strength is qualified  at 25 per cent above its intended Maximum Operating Pressure
  • Obtain approval from the Canada Energy Regulator to reactivate the deactivated pipe segment through a Leave to Open application

As an extra precautionary measure, we will re-inspect reactivated segments of the pipeline within the first two years of operation.

Preparing for In-Line Inspection at Jasper Pump Station

In order for the ILI tools to pass through the Jasper Pump Station without interruption, approximately 165 meters of new 24-inch pipe is to be installed between the station isolation valves in a combination of buried piping (permanent) and surface piping (temporary). The buried portions will remain in place for final tie-in of the pump station to the expanded system. The surface portion will be removed after the hydrostatic testing has been completed. All activities related to the installation of the surface and buried piping will be confined within the existing fenced area of Jasper Pump Station.

Preparing for In-Line Inspection at Mount Robson Provincial Park  

In Mount Robson Provincial Park, and within the fenced area of KML’s former Yellowhead Pump Station site, a section of the Trans Mountain Pipeline was removed to facilitate the temporary connection of the Anchor Loop.  Again, in order for ILI tools to pass through this segment, approximately 75 meters of new pipe will be installed.

Preparing for In-Line Inspection at Tool Launching and Receiving Sites

At the ends of each segment, temporary valves and assemblies will be installed in order to conduct in line inspections.   These are required to safety and effectively launch and receive the ILI tools.  These components will be installed at Hinton Station, Hargreaves Trap site, Darfield Station and the soon to be constructed Black Pines Station.

Hydrostatic Testing Prior to Reactivation

Public safety is top priority during the hydrostatic testing. For public safety, access to the sections of the pipeline right-of-way where the hydrostatic testing is being performed will be restricted. Temporary road and trail closures will be in effect for the duration of the test. We will use aerial and ground patrols and post extra signage in the area to guide the public away from the pipeline sections under test. As a routine safety measure, mobile environmental protection units, as well as pipeline maintenance and response crews, will be on standby at key locations along the test segment.

Natural Hazard Remediation

The Integrity Management Program has identified 21 natural hazard sites  requiring remediation in order to re-establish the operating integrity at specific sites along the pipeline.  These are all located in Jasper National Park and Mount Robson Provincial Park. 

As part of the reactivation program, these sites will all be upgraded to meet CSA code and NEB requirements.  Most occurrences are located at watercourse crossings and occur through long-term stream erosion, and possibly short-term flood events, the pipeline at most of these sites is exposed or nearly exposed, or at risk of becoming exposed.  A number of different forms of remediation methods could be used and selection of the appropriate measures will depend on the circumstances at each site.  

Refurbishing Valves

As part of the reactivation of the two inactive pipeline segments on the Trans Mountain Pipeline system, we will inspect and refurbish the existing deactivated block valves.    

New Valves

Six new check valves and four new permanent block valves will be installed as part of the reactivation program.  These will be installed for operational purposes and to minimize spills in an event of a leak.    

Four check valves will be installed in Jasper National Park and one in Mount Robson Provincial Park.  One will be installed between Darfield and Black Pines stations.

Existing Valve Automation

As part of the reactivation program, four existing 24-inch manual block valves will be automated to provide additional remote isolation capability.  Three of the valves are located between Hinton, Alberta and Hargreaves, BC, and one valve between Darfield, BC and Black Pines, BC.