Trans Mountain has developed comprehensive plans to manage construction noise and vibration at Westridge Marine Terminal.
Trans Mountain Expansion Project construction activities generating intermittent noise at Westridge may include foreshore earthworks, foreshore foundations, upland earthworks, marine foundations (pile driving) and tunnelling.
The Noise Management Plan was developed to mitigate the effects on residences within 300 metres of construction activity. The plan includes innovative measures to minimize sound levels in residential areas throughout construction. It also addresses National Energy Board Conditions 80 (Facilities Construction) and 86 (Burnaby Tunnel) for the Trans Mountain Expansion Project.
General noise mitigation measures for all activities include:
- Enclosures for compressors running at night
- Noise barrier walls or berms as buffers for on-site noise, including the Burnaby Mountain tunnel portal at Westridge
- Monitoring sound levels to verify that selected controls are effective and whether additional controls are needed. As construction progresses, additional mitigation measures or actions may be implemented.
- Best practices for vehicle and equipment operators, including site speed limits, placement of materials as barriers and good maintenance practices
- Avoiding use of engine retarder brake
- Use of temporary noise barriers and acoustic ducting (baffles) and acoustic blankets (lagging)
- Implementing a notification and complaint process to ensure the community is notified of activity and that any noise complaints can be investigated and addressed
Specific measures are planned to mitigate pile driver noise:
- When marine impact pile driving is necessary, noise shrouds will cover the hammers that drive piles into the ocean floor. The shrouds will dampen the sound of hammer impact by 65 to 95 per cent. It is estimated that with the use of shrouds, sound levels at the local receptors will be within British Columbia Oil and Gas Commission guidelines for day-long averages.
- Reduce pile driving energies where possible, such as installing dock and trestle piles using a vibratory piling method to reduce the use of an impact hammer. Benefits of this approach will reduce noise and vibration on land, as well as reduce intensity of noise below water and sound pressure emitted to the marine environment.
- Where possible, schedule activity so that multiple piles are not actively impacted simultaneously
- Consider additional mitigation controls where feasible for the shore and foreshore foundations if impact pile driving is needed
The daytime average noise levels near residential properties are expected to range between 57 and 64 dBA (average-weighted decibels). Some short-term activities will be louder than the average, with other activities being quieter than the average. Noise level targets have been set based on BC Oil and Gas Commission and Health Canada noise guidelines.
As a comparison, a household refrigerator generates about 55 dBA and an ordinary conversation in an office at a one-metre distance generates about 60 to 65 dBA. Sound mitigation efforts will be used throughout construction, reclamation and operations.
Primary work shifts at Westridge Marine Terminal are 7 am to 8 pm, Monday to Friday. As required, Saturday work shifts will be from 9 am to 8 pm. Night shift work if required will be low-impact noise activities such as maintenance and hand labour and noise levels will be measured and evaluated against target levels.
Noise levels will be measured during construction. If the average weighted noise level exceeds the target levels, the source of noise will be investigated and mitigation measures will be implemented to reduce the noise level.
