Trans Mountain has made significant progress on the Trans Mountain Expansion Project since construction began in late 2019. Construction is occurring simultaneously across most of the pipeline route, at terminals and at pump stations.

Many steps are involved in building a pipeline and activities happen in a phased approach. It isn’t unusual to see different levels of activity through the different phases. You can find more information about the pipeline construction process here.

During the winter months especially, construction projects can become more difficult for a variety of reasons, primarily to adapt to winter weather conditions. Specific or particularly harsh weather conditions could cause construction slowdowns and halts in the field.

To get a better idea of what this winter construction season holds, we spoke with Project Management team members in each region to see what can be expected during the next few months.


With about 47 kilometres of pipeline construction complete, crews in the Greater Edmonton region are finishing the final three kilometres and preparing for construction wrap-up. Mainline construction is finished and all 14 horizontal directional drills (HDDs) are complete. Over the next few months, crews are focusing on completing the two remaining horizontal directional bores. Once these trenchless crossings are complete, the crews will finish tie-ins, complete backfilling the site and demobilize heavy equipment. Cleanup and reclamation will continue until freeze-up and crews will begin preparing for hydrotesting, which is scheduled to finish prior to the winter break at the end of December. Work will also be continuing through the winter at the Edmonton Terminal, which is prepared to handle winter construction conditions.

Crews will return by early summer of 2021 to complete the remaining cleanup and reclamation work.

The winter construction season is also bringing a flurry of work to the Yellowhead region. An abundance of wet areas and wetlands means winter offers the opportunity to work through portions that are inaccessible to equipment and crews during spring, summer and fall, leading to periods where work stops, like during our spring breakup. Over the winter, work will be focused on pipeline construction between the Pembina River to west of the Town of Edson. Two HDDs, the Pembina River HDD and Sundance Creek HDD are also scheduled for this time. Work will also continue at pump stations throughout the region.

Working while the ground is frozen, along with the use of matting, means we are able to minimize soil rutting or mixing when operating heavy equipment. Topsoil is appropriately salvaged and conserved for use during reclamation activities, allowing us to return the land to its previous use.

Edson Pump Station - Concrete Pour

With the colder temperatures, techniques such as heating and hoarding for concrete pours and painting are being implemented. This provides consistent temperatures for concrete curing, allows paint to dry and the work to continue.

North Thompson

This winter crews will continue work in the North Thompson. Work in the region includes right-of-way grading, striping and clearing as well as continuing to develop approach/access sites. Water course crossings will be a key part of construction during the winter months. As in other regions, winter work will also continue at pump stations throughout the North Thompson.

Going into winter, the hope is that once the cold weather starts it will be here to stay. Continuous freeze and thaw cycles and heavy snow can both affect what work can be completed. We anticipate field construction slowdowns and halts due to winter weather conditions and factor that into the schedule. Avalanche risk will be a potential in some parts of the region and increased safety measures and training are put in place to address this.

BC Interior and Coquihalla – Hope

Similar to the North Thompson, construction crews are taking necessary steps to continue working in winter weather conditions. In Kamloops, construction will continue through the winter, with work on the Thompson River HDD, Ord Road and in Kenna Cartwright Park. Clearing and grading work south of Kamloops, as well as logging work, will continue as late into the season as weather allows.

In the Coquihalla Summit area, clearing, grading and blasting will continue as long as weather conditions remain safe to do so. This region is the most technically challenging stretch of pipeline construction on the entire Expansion Project due to the high number of steep slopes. The same crew will then move down into the Hope-Popkum area and begin similar work there. The Ohamil Camp Community is also scheduled to be occupied this winter.

Lower Mainland

In the Lower Mainland, construction activities are moving forward as scheduled. This winter, pipeline construction is scheduled to begin between Langley and Burnaby Terminal, while work continues at both Burnaby Terminal and Westridge Marine Terminal. Pipe installations, shallow foundation work, soil anchoring, bulk excavation and berm construction will all continue through the winter at Burnaby Terminal. At Westridge Marine Terminal, mobilization for the Burnaby Mountain Tunnel construction is scheduled to begin, while work will continue on the foreshore and on the water.

Winter conditions are less extreme in the Lower Mainland than in other regions along the line, however, it does mean a substantial increase in rainfall is expected at both terminals and along the pipeline route. We’ve prepared winterization plans to deal with the increased requirements related to erosion and sediment controls that come with heavier rainfall as well as plans if it snows.