Keeping the Vision: A Small Port’s Journey to Comprehensive Remediation of a Wood Treating Site

The former Pacific Wood Treating’s (PWT’s) wood-treating operations heavily impacted the Lake River Industrial Site (LRIS) that is owned by the Port of Ridgefield (the Port) and is located along the lower Columbia River in the city of Ridgefield, Washington. Site impacts included extensive dense nonaqueous phase liquid (DNAPL) contamination in soil and groundwater as well as ubiquitous metals, tetrachloroethene, pentachlorophenol (PCP), and dioxin contamination in soil. Dioxin contamination extended off of the site conveyed by stormwater into surface waterbodies and wetlands and into an adjacent residential neighborhood by truck tracking and aerial deposition. By partnering with the Washington State Department of Ecology (Ecology), the Port was able to make use of state grant funding, avoid the National Priorities List, and begin their vision of turning the site into a community asset. The Port performed a comprehensive investigation and remediation of the site over two decades to both address risk to human health and the environment and to return the Port’s property to productive use. The Port implemented remediation primarily as a sequence of strategic emergency and interim actions that were intended to function together as a final remedy. Remediation technologies employed on Port-owned property included steam-enhanced remediation of DNAPL in deep groundwater, excavation and off-site disposal of soil and shallow DNAPL impacts, installation of a clean soil cap across the site, and replacement of the aged storm sewer network. Dioxin-contaminated sediment in Lake River, a tidal backwater of the Columbia River, was removed using the precision-dredging method. Dioxin contamination in Carty Lake, a priority wetland habitat in the Ridgefield National Wildlife Refuge (RNWR), was removed by excavation “in the dry”; habitat within the lake was successfully restored and enhanced. The Port also led remediation of 29 residential properties and additional public rights-of-way with shallow dioxin contamination in soil. Accessible contaminated soil was excavated and disposed of off site; landscaping elements were carefully restored with minimal disruption to homeowners. This case study will follow the project, that included active remediation of nearly all environmental media, to understand how this small port district leveraged a variety of creative funding opportunities and advanced remedial technologies to lead and complete a major site cleanup. Work at the LRIS is now complete, and off-site work is nearly complete. The project opened Ridgefield’s only waterfront, closed by industry for over 100 years, to thriving public use—including dedicating a large swath of the waterfront as a public greenway. In cooperation with the Port, the RNWR has since made this greenway the locus of a new trail network across the refuge. The Port’s property is now ready for redevelopment as the focal point of a community that has consistently ranked as the fastest growing in Washington State.