Habitat Restoration and Environmental Remediation Success at a National Wildlife Refuge Wetland

The Lake River Industrial Site (LRIS), owned by the Port of Ridgefield (Port) in Ridgefield, Washington, USA, was home to a wood-treating facility from 1964 to 1993. The wetland habitat of Carty Lake immediately adjacent to the LRIS was found to be contaminated with dioxins and other wood-treating chemicals, likely a result of discharge from former stormwater outfalls. To inform the design of the cleanup action, Maul Foster & Alongi, Inc. (MFA) applied incremental sampling methodology (ISM) in wetland sediments. The ISM results were used to focus the active remediation to a limited area. MFA designed, permitted, and provided oversight for implementation of the remedial action, which involved temporarily dewatering and excavating sediment from 0.6 hectare of wetland. Through both careful design and an extensive grading effort, the restored wetland surface retained the nuanced topography and "pocket-habitats" of the preconstruction conditions. An approximately 550-meter-long failing bulkhead was also permanently stabilized in place by the construction of bioengineered soil embankments. The design and implementation also included significant landscape components; the wetland, transitional zones, and upland areas of the site were completely revegetated with native plant communities to provide wildlife habitat, prevent erosion, and restore culturally significant plants to an area historically used by Native American tribes.