Upper center: the Sumas Mountain Landslide |
For many years the creek, which flows
west to join the Sumas River, was dredged to manage the sediment and limit
downstream flooding. But, several years ago, the 225-acre slide was found to
contain naturally-occurring asbestos and metals – chromium, cobalt and nickel.
When the sediment dries, the asbestos
can become airborne and present a risk to human health and the environment. The
metals can affect plants on land and aquatic life.
An action plan
Sediment from the Sumas Mountain Landslide in Swift Creek |
Dredge sediment
• Dredge Swift Creek as necessary before
remedy starts.
Construct and repair levees
• Stabilize sediment piles.
• Use current sediment piles and
deposits to construct new levees.
• Deposit any extra sediment not used in
new construction in a repository and cover with clean soil.
• Repair, stabilize, and cap current
levees with rock and clean soil.
Construct sedimentation basins and traps
• Capture new sediment in a series of
traps and sedimentation basins.
Monitor, manage, and maintain
Another view of landslide sediment in Swift Creek |
• Monitor groundwater after
stabilization.
• Manage new sediment in traps and
basins by periodically removing and placing in the repository*.
*More sediment storage repositories will be needed.
Repository site locations may change depending on property availability. We
will amend the plan and prepare a supplemental Environmental Impact Statement
(EIS) for future repositories.
• Inspect and repair facilities
regularly.
• Dredge Swift Creek periodically as
needed and place this sediment in the repository.
Control access
Restrict use of and access to the levees
to prevent disturbance of, and exposure to, the sediment and airborne asbestos.
Controls can include:
• Fencing off levees, sediment capture
facilities, and storage basins.
• Placing legal restrictions on future
use of the properties.
• Inspecting areas to ensure compliance.
• Purchasing additional property or
easements may be required.
Public comments and community meeting
Before we adopt this plan, we’re asking
the public to review it and related documents, and to send comments from Oct. 7 to
Nov. 5, 2019.
We’re jointly hosting a public meeting
with Whatcom County to provide information, answer questions and receive
comments:
- Wed., Oct. 9, 2019, 6-8 p.m.
- Nooksack Valley Middle School, 404 West Columbia Street, Everson, Wash.
We have three documents up for review:
- Swift Creek Action Plan: describes the flood control and sediment management work to take place in the Swift Creek watershed.
- Consent Decree: the legal agreement between Whatcom County and Ecology under which the county will carry out the action plan.
- Public Participation Plan: explains how we and Whatcom County will keep people informed about the project and how people can provide input as it proceeds.
More information
By Larry Altose, communications manager, Northwest Regional Office
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