Chawathil First Nation
Last updated on February 21, 2024Area: Chawathil First Nation outside Hope
Large amounts of sediment and woody debris accumulated at three sites in the area, which caused flooding of roads and houses. The remediation process involves removing the sediment, reconstructing existing culverts, and repairing stream banks to reestablish proper drainage.
The culvert at Site CR-8 is located on an alluvial fan where the channel grade substantially flattens. In response to decreasing stream power, sediment aggradation occurs in the reach leading up to the crossing. The aggradation results in flow leaving the channel upstream of the crossing, flooding adjacent land. High flow eroded the road embankment fill and channel bank on the east side of the culvert inlet. The erosion has resulted in an undercut road embankment. Sediment was noted deposited inside the culvert, reducing the capacity of the crossing.
The subject culvert and channel at Choleqw Creek known as Site CR-9 are located on an alluvial fan where the channel grade substantially flattens. In response to decreasing stream power, sediment deposits in the reach upstream and downstream of the crossing. Channel aggradation resulted in flow leaving the channel to the west, flooding adjacent land, including across the North Service Road. During the 2021 AR event the channel and the crossing infilled with sediment and to a lesser extent debris. This resulted in a complete avulsion of the channel approximately 480 m upstream of the crossing. The original channel is now dry, with the current flow path poorly defined, through the forest and across the North Service Road, flooding the road.
The subject culvert at the West Tributary known as Site CR-10 is located on an alluvial fan where the channel grade substantially flattens. In response to decreasing stream power, sediment deposits in the reach leading up to the crossing. Channel aggradation resulted in flow leaving the channel upstream of the crossing and flowing west across an open field, across the North Service Road, and flooding three homes along Jackson Avenue and Chawathil Road.
Project Details
Total Budget:
$675,000
Projected Completion Date:
Completed
Community & Taskforce Members
- Chawathil First Nation
- Indigenous Services Canada
- Fisheries and Oceans Canada
- Ministry of Environment and Climate Change Strategy
- Ministry of Forests
- Ministry of Emergency Management and Climate Readiness
- Northwest Hydraulic Consultants
- Shxw'ówhámél Ventures
- Jim Dent Construction Ltd
Images
Image above: Before sediment removal.
Image above: After sediment removal.
Image above: Flooding on the north service road.
Image above: Looking upstream.
Risk Evaluation
Public Health and Safety
S-CR-8
Minor disruption to few.
S-CR-9
Minor, short-term disruption to local community or moderate disruption to few.
S-CR-Site 10
Moderate disruption to local community, or substantial disruption to few.
River Capacity
S-CR-8
Flow temporarily floods adjacent land.
S-CR-9
Flow floods adjacent lands resulting in prolonged flooding.
S-CR-10
Flow floods adjacent lands resulting in prolonged flooding.
Environmental
S-CR-8
Small, short-term loss or deterioration of important, unique, rare, or endangered habitat, species, landscapes, or culturally valued sites. Moderate, recoverable loss or damage of less valued habitat, species, landscapes, or sites.
S-CR-9
Moderate temporary or small permanent loss or deterioration of important, unique, rare, or endangered habitat, species, landscapes, or culturally valued sites. Moderate loss or damage of less valued habitat, species, landscapes, or sites.
S-CR-10
Small, short-term loss or deterioration of important, unique, rare, or endangered habitat, species, landscapes, or culturally valued sites. Moderate, recoverable loss or damage of less valued habitat, species, landscapes, or sites.
Infrastructure
S-CR-8
Impacts to infrastructure (erosion or scour, debris accumulation, infilling, etc.) leave the road vulnerable.
S-CR-9
Impacts to infrastructure (erosion or scour, debris accumulation, infilling, etc.) leave the road vulnerable.
S-CR-10
Impacts to infrastructure (erosion or scour, debris accumulation, infilling, etc.) leave the septic system vulnerable.
Project Links
Contact information
sec.info.epd@gov.bc.ca
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