By Lori Lovely
The Trans Mountain Pipeline was established in 1953 to create a reliable energy supply for Canada and the United States.
The initial capacity was 150,000 barrels per day, with four pump stations along the line and a marine loading dock. Since 1953, the pipeline’s capacity has been increased a number of times by twinning parts of the line as well as adding associated facilities. In 2019, Canada approved the Trans Mountain Expansion Project.
The Trans Mountain Expansion is essentially a twinning of the existing 1,150 km pipeline between Strathcona County, Alberta, and Burnaby, British Columbia.
It will create a pipeline system with nominal capacity going from about 300,000 barrels per day to 890,000 barrels per day.
New pipeline
The Expansion Project will construct about 980 km of new pipeline, 193 km of reactivated pipeline, 12 new pump stations, with 19 new tanks added to existing storage terminals in Burnaby, Sumas and Edmonton. Along with new storage terminals, there will be three new berths built at Westridge Marine Terminal.
The existing pipeline will carry refined products, synthetic crude oils and light crude oils with the capability for heavy crude oils. The new pipeline will carry heavier oils with the capability for transporting light crude oils.
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Construction is currently happening across Alberta and British Columbia for the Expansion Project. Work at Burnaby Terminal and Westridge Marine Terminal began in August 2019.
Step-by-step
Temporary roadways are currently under construction at the Burnaby Terminal, where the site is being prepared for 14 new storage tanks. One existing tank and the surrounding utilities will be removed to accommodate the new layout.
To house the tanks with enough capacity to contain 110 per cent of the tanks’ working volume, crews will first build a berm and containment area. Next, the foundations will be constructed by using poured-in-place concrete and compacted fill to create a concrete ring. Both the containment area and foundations will be covered by a specially designed synthetic liner that is anchored to the berm.
Layers of cathodic protection will be installed under the base of the tank to prevent corrosion. Leak detection piping and instrumentation will also be installed. The tank floor will be installed in sections and welded together. Tank walls will then be lowered into place by a crane and welded. After non-destructive testing is performed on the welds, the whole tank will be hydrotested to confirm its integrity.
Each tank will be topped by an internal floating roof to reduce odour and an external fixed roof. The floating roof will be built on the bottom of the tank and then lifted to enable installation of the legs, which are designed to travel up and down with the roof to keep it from contacting the floor when the tank is empty.
Around the perimeter, fire suppression and detection systems will be connected by piping systems to an on-site water reservoir and a foam concentrate tank. The expansion will also include an enhanced stormwater treatment system.
Other early work at the site includes tree clearing, top soil and ground soil stripping, reconfiguration of roadways for access, setting up systems for monitoring soil and water quality during construction and installation of temporary sound walls.
Changes to the terminal will also include relocation of existing delivery pipelines at the terminal to accommodate the expansion and connection to the existing electrical grid.
Burnaby Mountain Tunnel
Those pipelines will pass through Burnaby Mountain from the tank farm to the Westridge Marine Terminal. To achieve that, preparations for construction of the Burnaby Mountain Tunnel are underway. The 2.6 km tunnel will accommodate three 76 cm delivery lines that connect the two terminals.
After 101 secant piles on the portal wall are complete, boring operations will begin at Westridge, using a 122 metre tunnel boring machine that will produce a 4.43 metre diameter bore.
Commissioned from Herrenknecht to bore through Burnaby Mountain, the machine is capable of remaining stable in 13.5 bar of water pressure the equivalent of being more than 137 metres underwater.
A launch frame will support the TBM outside of the tunnel at Westridge. Thrust cylinders with 25,300 kN of thrust will enable the TBM to propel itself forward. As it pushes forward, the cutter head will simultaneously rotate and break up the earth.
Excavated material will exit through the screw conveyors and be transferred to the belt conveyor and onto muck cars for removal from the tunnel. A total of 38,700 neat cubic metres of material is expected to be excavated.
As the tunnel is excavated, concrete segments will be installed behind the TBM, which will place six pre-cast concrete segments, each of which is 1.5 metres wide, to form one complete ring. It will then propel forward again, beginning another cycle. More than 10,000 concrete segments will be installed, requiring 1,740 cycles to complete the tunnel.
Westridge Marine Tunnel
At the same time, work is underway at the Westridge Marine Terminal. Work includes marine, onshore and foreshore construction. Contractor Kiewit Ledcor TMEP Partnership (KLTP) is installing soil anchors to support widening of the main access road inside the terminal, while also completing soil improvement along the foreshore, which is being constructed of sheet pile cells that are filled with aggregate material and soil to establish a foundation.
The marine terminal expansion includes a new dock with three tanker berths to accommodate simultaneous loading of three Aframax-size tankers, a utility dock to moor tugboats, boom boats and emergency response vessels, additional delivery pipelines and an extension of land along the shoreline for new equipment.
At more than 90 metres long and 30 metres wide, the D.B. General is the largest revolving derrick barge on the West Coast of North America, with a maximum capacity of 700 tons. It will be used to assist with installation of 4.2 metre water piles to support new berth structures and trestles.
The longest pile is 80 metres in length, making it the longest single pile in Kiewit’s Canadian history. The heaviest pile is 149 tonnes. The General will also be used to install 24 dolphin jackets. These massive structures are installed on top of the dolphin piles.
Work continues on the federally owned Trans Mountain Expansion Project in Alberta and BC. Final completion is anticipated by the end of 2022
