Like you, we value water resources. That’s why extreme care and consideration is taken when planning our projects. On the Coastal GasLink Pipeline Project, our engineering and environmental field teams have spent many hours, gathering detailed information about rivers and streams along the pipeline route. For all of the bodies of waters we may cross, we’ve conducted field programs to collect information to support our applications to the BC Environmental Assessment Office and the Oil and Gas Commission. Learn more about how we take care of rivers and streams in our Q/A.
Q. How do you build a pipeline that crosses rivers and streams?
A. There are three ways a pipeline can cross rivers and streams. Two methods involve excavating a trench (ditch) and the third does not involve excavation in the stream channel. We decide on which method to use, based on our environmental and engineering studies (watch the video that shows the different types of crossings):
- Open cut – this method is used when the stream or water body is seasonally dry or completely frozen; we excavate a trench across a water way and then lay the pipeline into the trench.
- Isolation – water is temporarily redirected from its natural channel while the trench is excavated, and the pipeline is placed in the trench.
- Trenchless – through this method, we install the pipeline under the water body, without excavating a trench through the stream bed. There is no impact to the flow of the rivers and streams when completing a trenchless crossing, because we don’t construct through the bed or banks; this method requires a larger footprint of activity on either side of the stream.
Q. Who studies the rivers and streams? What are they looking for?
A. Since 2012, we’ve conducted environmental field programs that have been made of up of 72 fisheries and aquatics crews, who spent over 43,500 hours in the field. Crews included fisheries biologists, as well as Aboriginal participants, who gathered site-specific information on fish and fish habitat. This information helped us determine crossing methods, construction timing, and the best measures to reduce potential impacts.
Engineering field crews have spent over 16,500 hours in the field since the project began in 2012. They focus on surveying and investigating to help us refine the construction footprint and provide input into the engineering design. Assessments at water crossings are completed to ensure the appropriate crossing method is selected for each crossing. Their studies included geotechnical investigation on potential trenchless crossings, geophysical surveys, flow measurements, and assessments on water crossings.
Q. What happens to the rivers and streams during construction?
A. During construction, we monitor rivers and streams to make sure our plans are effective. This means monitoring both the stream and the surrounding river banks to understand if the measures we’ve put in place to reduce impacts are working as we expected, and to determine if changes are needed. We compare downstream measurements to upstream measurements to monitor the quality of the water, and to make adjustments when needed.
When measuring the water quality, we look at the amount of oxygen in the water, acidity, small particles and different ions that show up in the water, and the water temperature. These measurements help ensure watercourses retain the qualities needed to support fish following construction. These activities will happen throughout the installation of the pipeline on the site, multiple times per day. If the monitoring shows any unusual results, we’ll address it immediately. This could mean installing erosion/sediment control barriers; temporarily stopping work until the water quality returns to acceptable levels; or rescheduling work until conditions are more favourable (such as avoiding working during heavy rainfall, or working in the morning during freeze/thaw cycles when the ground is still frozen).
Q. How do you protect the fish and fish habitat during construction?
A. Fish matter to us. We’ve developed an Environmental Management Plan, which includes measures to protect fish and fish habitat during construction. This includes measures such as:
- Avoiding disturbance of or blocking access to important habitats during key times, such as spawning areas, migration routes and rearing areas.
- Constructing when watercourses are dry or frozen as much as we can.
- Isolating stream flows so work can occur during periods of reduced flow or in areas isolated from the flow.
- Relocating fish downstream from the work site during construction by a qualified professional.
- Replacing appropriate material to the streambed such as clean gravel as part of restoration.
- Re-grading, stabilizing, and seeding or planting approach slopes to grow vegetation to restore habitat along the river bank and minimize potential for erosion.
Q. What happens after construction? Are the rivers and streams still safe?
A. Just because construction is done, doesn’t mean we disappear! We monitor the construction footprint to see how the water and surrounding vegetation return as part of our 5 year post-construction monitoring. We look at the effectiveness of measures we put in place to reduce impacts. During the operations phase of the project, surveillance activities such as fly overs will be used to monitor the right of way on a regular basis. In addition our people on-the-ground may do site visits to follow-up on any noted change along the right of way.
By monitoring the rivers and streams after construction, we can ensure safe and reliable operations and measure how effective our mitigation and reclamation techniques were and determine if any further work may be needed.