GSI, working with Hart Crowser and the Oregon Department of Environmental Quality, managed all technical elements of the McCormick & Baxter Superfund Site cleanup project. GSI continues to work post-remedy to manage ongoing monitoring, including monitoring the passive recovery of creosote from the subsurface. Since GSI started working on this site in 1999 approximately 6,200 gallons of creosote have been recovered since then.


The McCormick & Baxter Superfund Site, located on the northeast shore of the Willamette River in Portland, includes 41 acres of land and 23 acres of sediments beneath the Willamette River. McCormick & Baxter Creosoting Company operated between 1944 and 1991, treating wood products with creosote, pentachlorophenol, and inorganic (arsenic, copper, chromium, and zinc) preservative solutions. Historically, process wastewaters were discharged directly to the Willamette River, and other process wastes were dumped in several areas on the site. As a result, significant concentrations of wood-treating chemicals have been found in soil and groundwater at the site and in river sediments adjacent to the site. The US EPA listed the site on the National Priorities List (NPL) in June 1994.

GSI’s Solution

  • Designed and implemented contingency groundwater remedy in the summer of 2003, and constructed a combination steel sheet pile and soil bentonite slurry wall surrounding 18 acres of the site to prevent migration of creosote to the Willamette River.
  • The sediment remedy, implemented in 2004, primarily consisted of a sand cap placed over 23 acres of contaminated sediment. Organophilic clay was used in the creosote seep areas. To protect the cap from erosion, the sand and organophilic clay were armored with a combination of rock and concrete blocks.
  • The sediment remedy included the re-grading and capping of the riverbank with 2 feet of topsoil; and capping a 1-acre portion of the contaminated sediments along a high pressure sewer main in September 2005.

Projects currently underway at the site include:

  • Semi-annual monitoring of inter-armoring porewater, sub-armoring porewater, and surface water
  • Crayfish sampling; quarterly monitoring of groundwater and NAPL levels
  • On-going Non-Aqueous Phase Liquid recovery
  • Routine operation and maintenance activities.

GSI, along with DEQ, has partnered with the University of Texas and Portland State University to conduct further research to determine:

  1. If gases escaping from the cap are significant potential contaminant pathway.
  2. What the remaining capacity of the organophyllic clay is.
  3. If biodegradation is occurring within the sediment cap.

The work on this project was featured as a case study in the EPA’s guidance document: Use of Amendments for In-site Remediation at Superfund Sediment Sites