Linnton Mill Restoration
The Linnton Mill Restoration project came about due to a need to restore the river corridor after being the location of several different manufacturing facilities. BCI was brought in to create a new river channel and a lowland habitat; both of which would allow for the reintroduction of aquatic and avian life to the area, as well as reduce flooding and begin the process of removing impurities from the environment. The project covered twenty-five acres of wetlands and required the extraction and handling of contaminated wood pile, soil, and debris.
Site Conditions
After decades as home to a plywood mill and other manufacturing facilities, the groundwater in the area was contaminated with high levels of VOC, PCB, Heavy Metals, and Arsenic. On top of that, there were approximately 2,000 wood pile embedded into the river bank to hold up in-water structures -- much of which had been treated with Creosote, a chemical that continuously leaches toxins into the environment.
Means and Methods
In order to create the river channel, approximately 350,000 yards of contaminated soil and debris had to be removed and contained in a safe, environmentally friendly upland habitat. BCI made use of a pre-existing concrete pad that spanned almost five acres to seal stockpiled contaminated soils from groundwater.
Linnton Creek became integrated into the new Willamette River channel via the removal of a twenty-foot diameter pipe placed in the 1930s. The integration of the fresh water with the stagnant, polluted waters helped encourage aquatic and aviation life to return to the newly restored ecosystem. Habitat features included the installation of anchored wood fish structures, large tree snags, and boulder habitat clusters.
A custom vibratory pile extractor/driver was designed by BCI in collaboration with American Piledriving Equipment (APE) and used to vibrate down up to 12’ into the substrate and extract from the structural area of the pile. The extractor proved successful in removing 99% of the pile without breakage. The 2,000 wood pile were removed and disposed of at a site certified to accept toxic waste. Tens of thousands of yards of buried wood and bark, entire buried buildings, and concrete structures were also removed and processed into reusable materials.
Through the use of strategic selection and careful planning, native plants and groundcover were reintroduced to the area to help the new wildlife thrive. The plants were chosen with the intention of helping filter out toxicities that may leach off the concrete pad.
Final Results
Upon completion, wildlife quickly took residence in the newly created wetlands connected to the Willamette River. Several benefits included improved water quality, stored floodwater, provided nesting areas for amphibians and birds, and helped to control erosion. The installed snag logs serve as perching posts for eagles, osprey and other birds in the upland areas. Rock and wood habitat structures are now a home to voles, ground squirrels, and mink. The backwater channel provides critical habitat for juvenile salmonids, lamprey, and other native fish.