Project Details
- Permitting & Engineering Design
Client
Port of Bellingham
Location
Bellingham Bay
Team Members
Carolyn Carlstrom
Jennifer Wynkoop
Katie Saltanovitz, PE
Steven Quarterman
Bellingham Eelgrass Mitigation & Cleanup
Did you know that over 50,000 acres of Puget Sound is covered with eelgrass? Eelgrass is an aquatic flowering plant common in tidelands and shallow waters along much of Puget Sound’s shoreline. It provides important habitat for many species such as herring, crab, shrimp, shellfish, waterfowl, and salmonids. Landau has worked with the Port and City of Bellingham for many years on the closure and cleanup of the Cornwall Avenue Landfill. A portion of the cleanup project extends into Bellingham Bay where a sediment cap will be placed, requiring the removal and eventual restoration of the eelgrass beds in that area.
96,000 sf of eelgrass will be planted on the site following cap placement, one of the largest eelgrass replacement projects in Puget Sound.
The Challenge
Under the Clean Water Act, eelgrass beds are identified as saltwater habitats of special concern, and a component of critical saltwater habitat under the City of Bellingham Shoreline Master Program. These environments are extremely fragile while also being critical to the survival of certain aquatic species. To effectively complete site cleanup, the existing eelgrass beds must be removed so a sediment cap can be installed. This sediment cap will contain and prevent the spread of existing contaminants and debris while also providing a healthy substrate for both plant and fish communities.
Our Approach
The approved cleanup action includes intertidal and upland excavation of landfill debris. A sediment and shoreline cap will protect remaining material that cannot be excavated. Landau is also developing designs to recontour a portion of the subtidal area to create a fish habitat and eelgrass mitigation bench that will also provide shoreline slope stabilization. Placement of the nearshore sub-tidal and intertidal cap will displace existing eelgrass beds; however, the newly formed habitat bench will be replanted with eelgrass to serve as mitigation.
The Solution
The remedial design is intended to minimize intrusion of the project into aquatic habitat and, through eelgrass restoration, to achieve overall improvements in shoreline ecological functions over time, providing no net loss of habitat area and functions.
The mitigation includes creation of an eelgrass habitat bench to assist in retaining sediment on the southern half of the site. The habitat bench will create a 1:1 replacement area for transplanting, voluntary recruitment, and spreading of the restored eelgrass.
Approximately 59,860 sf of eelgrass is currently present on the site. The completed project will create 96,000 sf of eelgrass mitigation area. Stringent performance standards and monitoring plans will be put in place to achieve the desired outcomes for restoration of the eelgrass beds.
