Most of the maintenance work we perform to keep the Trans Mountain pipeline operating safely can be done while product is still flowing, but certain projects require the line to be shutdown in order to safely undertake the work. During the shutdown window our crews and contractors work around the clock and in a variety of locations, to get the work done. We sat down with Dan Bonner, Operations Engineer, to learn more about our most recent shutdown, which occurred in July.

What is a mainline shutdown?

Mainline shutdowns involve stopping the flow of product out of Edmonton Terminal and isolating or isolating portions of the Trans Mountain Pipeline to complete maintenance activities.  Work at certain pump stations and terminals, like electrical work that will shut down critical pumps, also requires the mainline to be shut down.

How often does this happen and why?

We typically plan for two mainline shutdowns per year, in the spring/summer, and again in the fall, but occasionally have three or more shutdowns in a single year. To minimize disruption to operations, multiple activities are coordinated into the same outage window.

We complete mainline shutdowns for multiple reasons including pipeline integrity, capital project work, operations, which includes items like valve replacements, pump rebuilds or mainline relief modifications, emergency response, abnormal operation conditions and modifications to existing assets.

What projects were completed during the most recent shutdown?

Two primary projects were completed during the July 2020 shutdown:

A cutout and replacement of a previously repaired integrity feature near our Kamloops Terminal. Although a repair was completed at this site, the Pipeline Integrity group will complete a detailed analysis of the feature to help characterize similar inspection tool run results found elsewhere on the line.

Installation of a new mainline block valve was completed near Merritt. Work is continuing at this site, with plans to have remote automation of the valve complete in 2020.

Mainline Shutdown BISEP Isolation Tower


Some additional activities occurred during the outage, including electrical maintenance with BC Hydro, and communications upgrades with the Expansion Project in Kamloops. All outages accounted for, the mainline was shut down for 33 hours.

How did COVID-19 make this shutdown different from other shutdowns?

We established safe working protocols for COVID-19 prevention, and strict hygiene practices and PPE (including fire-retardant masks) were required.

The more challenging aspect, as we’ve seen in our personal lives, was restricting social interaction. We moved to digital meetings, rather than having the full crew assemble in a pipeline maintenance shop, restricted group gathering for meals and breaks which meant we missed the opportunity to catch up before or after splitting into day and night shifts.

How long is the planning process for a shutdown like this?

Once projects are set and an outage date is determined, the planning process typically starts several months in advance. A high-level desktop study is completed to determine the optimal way to isolate and drain a given segment, and how other planned maintenance activities will impact the operations, with a goal of minimizing outage time as much as possible without impacting worker safety or risk to the environment.

Detailed job plan development, contractor procurement, and field execution of preparatory works will typically occur one to two months in advance of the outage date.

How many people are involved?

Although the local operations and pipeline integrity crews completed most of the preparatory works, Trans Mountain personnel from across the line came to support during the shutdown. Between the two sites, about 35 Trans Mountain staff were involved in the shutdown, plus our control centre operators in Edmonton.

Contractors were also brought in, including our regional contractors, welders, linestop technicians, vacuum trucks, a pig tracker, and others – in total it was about 45 people.

Mainline Shutdown Pup Joint Cold Cuts


What does a normal shift look like during a mainline shutdown?

We start each shift with a tailgate/toolbox safety meeting and permit issuance by Trans Mountain operations, including all contractor personnel, and then head off to our assigned locations.  

Overall job schedules are typically timed around the mechanical shift, to maximize daylight for the cutout and welding. With isolation and drain-down complete, crews will cold cut the pipeline, install vapour barrier mud plugs and complete welding of the new pipeline joint and mainline block valve. The welds are x-rayed, and any new assets, such as valves are commissioned prior to completion of a Pre-Startup Safety Review checklist and handover to operations in a state of readiness.

The last shift involves removing locks and opening mainline isolation valves. The pipeline is then restarted, and operations resume.