Designing and engineering a pipeline and associated facilities is a lengthy and detailed process.

Pipeline construction consists of a number of distinct activities that each contribute to the long-term integrity of the pipeline, as well as minimize the impact to the environment and to the landowner.

Pipeline integrity starts with sourcing the materials – oil pipelines are generally constructed from steel with a diameter typically ranging from 100 mm to 1,200 mm (4 inch to 48 inch). The highest quality steel is used. It is manufactured to stringent Canadian Standard Association (CSA) specifications, which include chemistry and material properties. Through production, transportation to the job site and installation, quality management processes ensure the pipe fully meets the requirements.

We are using three distinct construction methodologies in the Trans Mountain Expansion Project to place the pipe in the ground: conventional construction (often referred to as baselay), trenchless construction and water crossing construction.

Conventional Construction

Name: Trans Mountain
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For the majority of the pipeline route, conventional construction will be used. This is the style of construction most people think of when they imagine pipeline installation. Skilled tradespeople use specialized machinery in the 12 important steps to build a pipeline.

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This method is called open-cut construction and will be used in both urban and rural areas along the Expansion Project route.

Urban Pipeline Construction

Rural Pipeline Construction

: Once a pipeline is approved and a route is finalized, crews survey and stake the right-of-way (ROW) and any temporary working space required for construction.
: Trees and vegetation are removed from ROW and the topsoil is removed and stockpiled and protected for future reclamation activities.
: The ROW is then leveled and graded to provide a safe working space. The crew installs silt fences along edges of streams and wetlands to prevent erosion of disturbed soil and for protection of the water courses.
: Individual lengths of pipe, ranging from 12 to 24 metres long, are brought in from stockpile sites and laid out end-to-end along the right-of-way.
: Individual joints of pipe are bent using a hydraulic bending machine for directional changes and to fit the terrain.
: Welders join the pipes together using either manual or automated welding processes. Both manual and automatic welds are of the highest quality, with every weld inspected and certified using non-destructive examinations including X-ray or ultrasound methods.
: Coating on the outside of the pipeline is used to prevent it from corrosion or rusting. The new pipe, and any repairs to the existing pipe, is typically coated with fusion bond epoxy. In rockier areas, enhanced external coatings such as concrete or abrasive resistant fusion bond epoxy (ARO) will be used to protect the pipe and to provide additional mechanical protection. Prior to lowering the pipe section into the trench, a high-voltage tool checks the integrity of the coating to detect even the smallest defect. If a defect is noted, an epoxy repair coating is applied.
: Excavators dig the trench to the required depth and place the excavated soil to the side.
: The welded pipeline is lowered into the trench using heavy lifting machines called sidebooms.
: Once the pipeline is in place, select backfill may be used to bed and protect the pipe. Following this, subsoil and topsoil are replaced in the sequence in which they were removed.
: Hydrostatic testing is used to verify the integrity of the pipeline prior to activation and use. This process is a well-established industry practice used to confirm the ability of the pipeline to operate safely and determine if any repairs are needed. The process includes filling the segment of pipe with water to pre-determined limits of pressure, for an extended period.
: Valves are installed at intermediate locations as required by the pipeline design and the Canadian Standards Association pipeline code. The valves are used once the line is operational to shut off or isolate part of the pipeline.
: The final step is to reclaim the pipeline right-of-way, removing any temporary facilities, re-seeding, replanting and restoring the land. Plantings are controlled on the right-of-way for pipeline safety and monitoring.

Water Crossing Construction

River and watercourse crossing construction techniques will be used where the pipeline crosses a body of water. There are two techniques to draw on: stream isolation (dam and pump technique) or horizontal directional drill. In some circumstances, where flows are too high for stream isolation and geotechnical conditions preclude trenchless techniques, we will use an open cut crossing of the watercourse with conventional construction methodologies.

With the stream isolation technique, the stream is temporarily dammed and rerouted through temporary pumps or using piping often referred to as a flume. The pipe is then installed using conventional construction techniques before the dam is removed and the stream returned to its normal flow path. Great care is taken to preserve the environmental features around the stream such as the wildlife and aquatic habitat provided within the riparian zone.

Water Crossing Construction (Isolated Trench)

Stream Isolation

Horizontal directional drill (HDD) technique is used for larger water crossings depending on geotechnical conditions at the stream crossing. This methodology is described within trenchless construction techniques.

Conventional pipeline construction will take place on either side of the water crossing.

Trenchless Construction

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Building a Pipeline

Conventional Construction

Conventional Construction

Water Crossing Construction

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