As part of the Port Mann Highway 1 project, important environmental and habitat work is taking place on‐and off‐corridor to deliver the project to the highest environmental standards. This work has four main components: Enhancement, Compensation, Construction timing, Protection/Restoration.
Protection of Wildlife
There are many mammal species that could be encountered in the Fraser River such as harbor seals, California and Steller's sea lions, grey whales and killer whales. During the construction of the new Port Mann Bridge, timing of construction activities is the key measure for mitigating potential effects to marine mammals and their prey species. Instream activities, including pile driving, are restricted between March 1 and July 15th to protect eulachon and outmigrating juvenile salmon, which also mitigates for potential effects to seals and sea lions when they are most likely to be present in the river. When pile driving for the new Port Mann Bridge is occurring, vibratory hammers are the preferred method for in-river work. Impact hammering is used only selectively. The predominance of vibratory hammer use during pile driving is the key measure to reduce potential acoustic effects on marine mammals that may be present in the area during pile driving.
An innovative construction method developed by Kiewit/Flatiron for this project was the use of full-length piles at Pier N1, the main instream pier for the cable stay portion of the bridge. Rather than driving and splicing of piles, which involves numerous small steps, piles were welded to their full length prior to driving and then driven with the Derric Barge General, a marine crane brought in specifically for this work. This innovation allowed the piles to be driven in a single event and minimized the necessary use of impact hammering for the entire N1 pier work. The full-length pile technique also lessened the duration of pile driving for the N1 pier. Hydrophone monitoring was conducted at all times when impact hammering was underway. If at any time hydrophone monitoring detected underwater pressure exceedances of 30 kPa, mitigation measures such as using impact hammer during low tides (high velocity flows) and use of bubble curtains were implemented to manage the potential acoustic and sound pressure effects to fish (as well as marine mammals).
Additional Environmental Considerations
In addition to protecting marine wildlife, the Port Mann Bridge has been designed to accommodate cyclists, pedestrians and transit. It is expected that this new design will reduce greenhouse gases by 10,000 to 15,000 tonnes per year, as 20,000 people are expected to utilize transit and cycling by 2031.