Trans Mountain Pipeline (ULC)
Trans Mountain Expansion Project
Volume 7
Volume 7 - Risk Assessment and Management of Pipeline and Facility Spills
Page 7–136
TABLE 7.1.12
LIKELY ENVIRONMENTAL EFFECTS OF CLWB SPILL DURING SPRING OR FALL TO THE FRASER RIVER NEAR HOPE, BC
Fraser River, Spring or
Fall Season
LIKELY OIL SPILL EFFECTS
Spatial Extent
Magnitude
Time to Recovery
Aquatic Receptors
Aquatic Vegetation
The side channel of the Fraser River is somewhat isolated from the main
Fraser River because of intermediate water levels. Islands and sandbars
are present and visible. Little if any riparian habitat is inundated. Aquatic
vegetation in the side channel has little exposure to floating oil, and
generally low sensitivity to dissolved hydrocarbon constituents. Little of the
oil sinks in this area.
Medium. Some aquatic vegetation is contacted by the spilled oil. Oil spill
recovery efforts in the side channel result in damage to the habitat. Oil
exiting the side channel to enter the main channel is carried up to 60 km
downstream, but little aquatic plant habitat is present in the main channel.
Spilled CLWB enters the side channel of the Fraser River, moving along it and
entering the main channel. Because more of the oil is retained in the side channel,
more habitat disturbance results from recovery efforts. Recovery is generally
complete within 12 to 24 months.
Aquatic Invertebrates
The side channel of the Fraser River is somewhat isolated from the main
Fraser River because of intermediate water levels. Islands and sandbars
are present and visible. Little if any riparian habitat is inundated. Aquatic
invertebrates in the side channel have moderate exposure to dissolved
hydrocarbon constituents. Little of the oil sinks in this area.
Medium. Some aquatic invertebrates are killed by exposure to dissolved
hydrocarbons in the side channel. Oil spill recovery efforts in the side
channel result in damage to the habitat. Oil exiting the side channel to
enter the main channel is carried up to 60 km downstream, but flow in the
river is such that acute toxicity to aquatic invertebrates is unlikely. Some oil
sinks and is deposited to sediment in areas of low flow and silty sediment.
This aquatic invertebrate habitat remains compromised.
Spilled CLWB enters the side channel of the Fraser River, moving along it and
entering the main channel. Because more of the oil is retained in the side channel,
more habitat disturbance results from recovery efforts. Efforts to recover sunken oil
from backwater areas of silty sediments take longer, but the natural flow regime of
the river tends to periodically erode and re-suspend sediment in these areas.
Recovery is generally complete within 12 to 24 months.
Fish and Fish Eggs
Fish, including potentially inward migrating salmon in the fall, could be
present in the side channel. Eulachon are not likely to use spring spawning
habitat this far up the Fraser River. Mortality of fish is possible in the side
channel, because of its small dimensions, but flow characteristics have low
turbulence, so droplet formation is limited. Flow is more turbulent in the
main Fraser River, but the oil is somewhat weathered by the time it leaves
the side channel, and the flow volume is still large, limiting the potential for
fish mortality.
Medium, and localized in the side channel.
Acutely lethal conditions persist for only about one day. Oil spill recovery efforts result
in disturbance of this aquatic habitat. Recovery is generally complete within 12 to 24
months.
In-water Amphibians
Amphibians may be spawning in the spring, but likely in protected areas
not exposed to the high summer river flows. Turtles may be present and
may be breeding, but also in more protected areas. Direct mortality is
unlikely for turtles, although some limited mortality of amphibians in the
side channel, or riparian areas of the main Fraser River is possible.
Low to Medium, because amphibians and turtles are likely to occupy
protected areas, not exposed to the main flow of the Fraser River.
Spilled CLWB enters the side channel of the Fraser River, moving along it with river
flow. Oil spill recovery efforts result in disturbance of this habitat. Recovery is
generally complete within 12 to 24 months.
Terrestrial Receptors
Shoreline and Riparian
Vegetation
Some shoreline and riparian vegetation is oiled along the overland flow
path to the side channel, but little riparian habitat along the side channel or
main Fraser River is contacted by oil, because of intermediate water levels.
Annual plants contacted by the spilled oil are likely to be killed. Leaves of
perennial plants, shrubs and trees will also be killed, but these plants are
likely to survive and regenerate. Effects are largely confined to the
overland flow path and the area where the oil enters the side channel.
Low. The combination of direct contact with spilled oil, as well as oil spill
recovery activities result in the physical destruction, and then
reconstruction of terrestrial habitat near the spill location. Effects on
riparian habitat of the side channel and main Fraser River are minimal.
The overland flow path and areas around the spill location are heavily disturbed by
clean-up activities in the first year following the oil spill. Recovery of terrestrial habitat
begins between 12 and 24 months after the spill, and is effectively complete after
about 5 years.
Soil Invertebrates
Soils are oiled along the overland flow path to the side channel. Riparian
areas of the side channel and main Fraser River are minimally affected.
Low. The combination of direct contact with spilled oil, as well as oil spill
recovery activities result in the physical destruction, and then
reconstruction of terrestrial habitat near the spill location. Effects on
riparian habitat of the side channel and main Fraser River are minimal.
The overland flow path and areas around the spill location are heavily disturbed by
clean-up activities in the first year following the oil spill. Recovery of terrestrial habitat
begins between 12 and 24 months after the spill, and is effectively complete after
about 5 years.
Mammals
Grizzly Bear
The grizzly bear as a receptor is also intended to represent other
omnivore/carnivores (such as raccoons). A small number of individual
animals might come into contact with spilled oil in the overland flow path,
the gully, the side channel, or stranded along shorelines of the main Fraser
River channel.
Low, because partially oiled animals would not be likely to die as a result of
exposure. However, disturbance caused by oil spill recovery activities
could cause an alteration of habitat use during the spring, summer and fall.
The overland flow path and areas around the spill location are heavily disturbed by
clean-up activities in the first year following the oil spill. Recovery of terrestrial habitat
begins between 12 and 24 months after the spill, and is effectively complete after
about 5 years.
Moose
Moose or other ungulates are potentially affected, as the gully and forested
riparian areas of the river could provide sheltering and feeding habitat.
Moose tend to be solitary, so effects of external oiling on more than a few
individual animals are unlikely.
Low, because moose have a large home range, oil spill recovery activity
would quickly cause them to leave the area. However, disturbance caused
by oil spill recovery activities could cause an alteration of habitat use during
the spring, summer and fall.
The overland flow path and areas around the spill location are heavily disturbed by
clean-up activities in the first year following the oil spill. Recovery of terrestrial habitat
begins between 12 and 24 months after the spill, and is effectively complete after
about 5 years.
