Cascade Pole Site Remediation
The Port of Olympia and the Washington State Department of Ecology are actively partnering on a hazardous waste remediation for this former wood treatment facility on Port property. This site was determined to be a hazardous waste site under state law in the 1980's. Since that time, the Port and Department of Ecology have been working together to return this property to a productive use
Site History
The 17-acre former Cascade Pole Company (CPC) site and adjacent parcels of land are owned by the Port of Olympia. From 1939 to 1957, numerous wood treating companies leased this land from the Port. The companies used chemicals to preserve structural wood products, primarily utility poles and railroad ties. From 1957 until 1986, CPC operated on the site. Their above ground structures were dismantled, cleaned, and disposed of off-site in 1990.
Two main chemicals were used - creosote and pentachlorphenol. Creosote is primarily composed of polycyclic aromatic hydrocarbons (PAH) much like tar oil. Pentachlor-phenol (PCP) dissolved in a carrier oil became the primary wood preservative beginning in the early 1960's, though creosote was still used.
Unfortunately, these chemicals entered the environment as part of industry practices that were common until the late 1970's and early 1980's. Chemicals were spilled during handling in the plant, and waste material was simply dumped onto the ground or piped out to Budd Inlet, contaminating the offshore sediments.
The practices were stopped in the early 1980's due to increased environmental awareness, industry economics, and tighter governmental regulations.
In 1990, the Department of Ecology, Port of Olympia, and CPC entered into a court-ordered agreement to start remediating the environmental problem at the CPC site. In 1992 and 1993, a sheet pile cutoff wall and contaminant collection trench were installed. In addition, a ground water pump and treat system was installed to control the spread of contaminants out of the uplands. The pump and treat system consists of wells, which pump water from the ground to a treatment plant for removal of contaminants. The treated water is discharged to the LOTT treatment plant outfall.
In 1995, after several years of negotiations, the Port of Olympia and CPC entered into an agreement that allowed the Port to take control of the site and future remediation efforts at the site. DOE and the court gave CPC permission to relinquish control in exchange for a lump sum payment and annual cash payments toward site remediation activities.
The Remediation Process
Since 1995, the following treatment methods have been installed to reduce the contamination.
Slurry Wall and Sheet Wall
The slurry wall is in place to limit the spread of contaminated ground water off the site. It is made of a two-foot wide trench cut into the ground then back-filled with a clay and water mix.
In addition to the slurry wall, the sheet pile wall, installed in 1992, blocks the spread of contaminants off the site. The sheet wall is made of interlocking steel sheets and is located on the east side of the site.
The two walls connect to an aquitard, a naturally occurring formation of silts and clays, that underlies the entire site 20-28 feet below the ground. The aquitard and the slurry wall form a barrier minimizing the chance that contaminated ground water will leave the site.
Additional Groundwater Extraction System
The contaminated groundwater is collected by pumping water from extraction wells throughout the site. This water is treated at a plant to remove contaminants prior to being pumped to the LOTT treatment plant outfall. Over a five-year period, 6,500 gallons of wood preserving product were captured by this system. The Port is expanding on the original groundwater pump and treat system installed in 1993.
Sediment Replacement
The tidal areas outside the slurry wall and sheet wall contain contaminated sediment, which will be excavated and then stored inside the slurry wall. The sediment will be replaced with clean material. This excavation took place during 2001.
Site Cap
Eventually, the entire site will be capped with either an asphalt or plastic liner cap. The caps will keep rainwater from entering the site. The groundwater extraction system will continue to pump and treat water to minimize the chance of leakage from the slurry or sheet wall.
Future Land Use
Although plans have not been finalized for land uses after remediation efforts have been completed, the Port's comprehensive plan would put the southwesterly portion of the site to cargo uses for the marine terminal and the northeasterly side for public areas, environmental awareness, and marina support uses.
If you have further questions concerning the activities at this site, please call the Port of Olympia at (360) 528-8000.