Aquatic environment
Fish and fish habitat
Fish and fish habitat play vital roles in aquatic ecosystems. Fish species assessed include salmon, sturgeon, eulachon, trout, char and other culturally important and traditional use fish species.
Anticipated effects from project activities
- Dredging, sediment disturbance and underwater noise may affect fish behaviour, mortality or injury
- Fish are anticipated to be resilient to changes in water and sediment quality, as changes are likely to be periodic and reversible
- Permanent habitat loss in the footprint of new infrastructure
How we will reduce effects
- Conduct in-water work during least-risk timing windows
- Use soft start procedures and daily work stoppages to minimize noise impacts
- Implement vessel speed limits to reduce noise and disturbance
- Conduct fish salvage to safely relocate fish from dewatered areas
- Develop a Fisheries habitat offsetting plan to restore and enhance aquatic and riparian habitat
Future conditions
- Temporary residual effects on fish and fish habitat are expected during tunnel construction and removal of temporary infrastructure
- Restoration efforts will focus on offsetting the effects of the construction and habitat loss
- Cumulative effects on fish health, behaviour and habitat are expected to be of low magnitude, short to medium term and reversible
Groundwater
Groundwater supports plant growth, provides wildlife habitats and stores carbon and nutrients. Groundwater also feeds surface water bodies like ponds, streams and rivers.
Anticipated effects from project activities
- Removing vegetation, compacting soil or pumping water out of construction areas may cause temporary effects to groundwater levels and flow
- Removing water from a location may also temporarily change groundwater levels and flow during early construction
How we will reduce effects
- Fill excavated areas using clean and similar soil types
- Follow environmental guidelines to restore land and groundwater after construction
- Install underground barriers to prevent groundwater from seeping into work areas and limit impacts to salt wedge
- Develop a groundwater quality monitoring program
Future conditions
- With mitigation in place, no residual effects are anticipated on groundwater during operation of the new tunnel
Marine mammals
Marine mammals are in the local environment and may interact with areas near the project footprint. Marine mammals assessed include harbour porpoise, humpback whales, grey whales, California sea lions, Stellar sea lions and harbour seals.
Anticipated effects from project activities
- Construction may cause temporary behavioural changes and disturbance for seals and sea lions
- Construction vessels in the river may cause temporary disturbance to all marine mammals from additional underwater noise
- Construction may cause temporary changes in the abundance and distribution of prey
How we will reduce effects
- Comply with marine mammal regulations
- Schedule in-river construction activities within the least-risk timing windows
- Develop an underwater noise mitigation strategy, including underwater noise monitoring during construction
- Use speed limits to lower underwater noise and reduce the risk of vessel strikes on marine mammals
- Use “soft starts” – gradual noise increases that offer marine mammals time to leave the area
- Schedule daily work stoppages to minimize impacts on fish
- Implement and follow sediment and waste management procedures to keep water clean
Future conditions
- Residual effects are expected to be mostly short-term and reversible
- Underwater noise from traffic through the new tunnel has the potential to negatively affect sea lions and harbour seals, such as by masking seal vocalizations, however effects are predicted to be negligible; no effects for whales and harbour porpoises are predicted
- Given nearby developments and the impact of existing cumulative effects, the project may cause short-term effects on Southern resident killer whales, such as underwater noise from vessel traffic, reduced availability of prey and exposure to contaminants
Marine use
In-river work could potentially affect marine access and area use. Marine use also includes commercial transportation; commercial, recreational and Indigenous fisheries; marine tourism and recreation; and other marine uses by First Nations.
Anticipated effects from project activities
- Temporary, short-term impacts on navigation, requiring vessels to alter course or change speed
- Temporary navigation impacts from river closures required to immerse the tunnel elements; the project anticipates a minimum of six closures for approximately 48-hour durations
- Potential temporary delays for commercial, Indigenous and recreational fishers due to navigation restrictions
- Temporary disruptions to marine tourism and recreation access
How we will reduce effects
- Implement a Marine construction staging plan, which will outline marine areas used for construction activities, construction schedule and navigation detours to reduce marine disruptions
- Develop marine supply chain logistics and operating procedures to minimize disruptions
- Implement fisheries access management protocols to allow safe, unimpeded access to fish harvesting areas
- Develop a Marine Communications Plan to keep marine users and regulators informed of Project activities
Future conditions
- No anticipated effects on navigation once the new tunnel is in operation
- Improved marine connections to key transportation hubs like the region’s ports, airports, highways, Tsawwassen ferry terminal and the United States border
- Changes to the marine setting may affect the area’s appearance but will be mitigated through vegetation restoration
- Cumulative effects are anticipated to be mostly low in magnitude and continuous during construction, but short-term and reversible
River hydraulics and morphology
River hydraulics and morphology refers to the river depth, speed and direction of flow of the Fraser River, including sediment transport, riverbed levels and bank stability.
Anticipated effects from project activities
- Minimal changes to flow distribution into Ladner Reach and the Cannery Channel
- Potential minor, localized changes to the riverbed within about 1.2 km upriver and downriver of the Tunnel corridor area and the Temporary moorage area
- No predicted effects to the dynamics of the salt wedge
How we will reduce effects
- Conduct in-river activities outside of the freshet season (when river flows are high) to help minimize erosion (scour) and the buildup of sediment
- Minimize the duration of the open immersed tube tunnel trench to prevent sediment from building up
- Limit in-river construction to least-risk timing window
- Use underwater separation walls to minimize in-river footprint and disturbance to the river
Future conditions
- Changes to riverbed and river flow near the tunnel and temporary moorage area are anticipated to be minor and partially reversible
Surface water and sediment quality
Project works could affect surface water and sediment quality, including within rivers and streams.
Anticipated effects from project activities
- Dredging and soil removal are expected to change surface water quality and increase suspended sediment
- Temporary and reversible impacts on water and sediment quality are expected during construction due to sediment disturbance, runoff from construction areas and release of alkaline material from concrete work
How we will reduce effects
- Implement an environmental monitoring program to track water quality throughout all project phases
- Use erosion and sediment control measures to control water runoff, erosion and sediment movement
- Use water treatment to meet environmental standards before releasing water from the site
- Implement and enforce spill prevention and emergency response procedures
- Dispose waste materials properly to protect the water surface
Future conditions
- Long-term positive effects as a result of new stormwater management systems, drainage infrastructure and improvements to water runoff treatment
- Cumulative effects are expected to be minor, short-term and reversible with mitigations in place
