Western Processing Company, Inc.
EPA ID# WAD009487513
EPA Region 10
King County

9th Congressional District

Other Names:
Last Update: April, 2012

Hide details for Site DescriptionSite Description

The 13-acre Western Processing Company, Inc. site is located in the highly industrialized Kent Valley, about 20 miles south of Seattle and 2 miles north of the city center for Kent. The company originally reprocessed animal by-products and brewer's yeast, but the business expanded in the 1960s to include recycling, reclaiming, treating, and disposing of industrial wastes. These included electroplating wastes, waste acids (pickle liquor and battery acid), zinc dross and flue dust from steel mills, transformers, waste oils, pesticides, and spent solvents.

From 1961 until 1983, about 300 businesses transported their industrial wastes to the Western Processing site. The company stored 72 bulk tanks and approximately 5,000 drums on the site property. The property also contained other containers, buried materials, open waste piles and 10 lagoons. In 1983, the company was permanently closed by federal court order.

As of the 2000 census, 78 people lived within one mile of the site and 78,327 people lived within three miles of the site. The nearest drinking water well for the City of Kent (pop. 86,660) is located more than a mile from the site. This aquifer is much deeper than the contaminated aquifer at the site.

Site Responsibility: This site is being addressed through federal, state, and potentially responsible parties' actions

NPL Listing HistoryDates
Proposed Date:12/30/1982
Removed Date:
Withdrawal Date:
Final Date:09/08/1983
Deleted Date:

Hide details for Threats and ContaminantsThreats and Contaminants

Media Affected:
Contaminants found in groundwater and sediments include volatile organic compounds (VOCs), phenols and heavy metals. Soils contained VOCs, polychlorinated biphenyls (PCBs), phenols, and metals. VOCs and metals were detected in surface water.

Hide details for Cleanup ProgressCleanup Progress

Early Actions:
Beginning in 1983, EPA removed over 2,400 truckloads of chemical waste, contaminated soil and other debris from the site. This included 127 drums of PCB contaminated liquids; 160,170 gallons of flammable/combustible liquids or solvents; 51,280 gallons of corrosive liquids; 250,160 gallons of other waste liquids; and 1,944 cubic yards of solidified flammables and paint sludges. EPA and the State of Washington also capped a waste material pile with an impermeable, flexible cover, regraded portions of the site, installed a stormwater runoff system, and constructed a lined impoundment for stormwater collection and treatment.

The removal action was completed by November 1984 with the exception of approximately 6,000 gallons of a dioxin-contaminated oily liquid that was discovered in one storage tank. This material was successfully treated in 1986 on site. Residual material from the treatment process was shipped to Chemical Waste Management's SCA incinerator in Chicago.

Source Control:
In 1988, a soil-bentonite slurry wall was constructed around the 14.5 acre site to laterally confine the remaining site contaminants to the site boundaries. This 4400’ long permiter wall is 30” wide and 40’ to 50’ deep. The wall is keyed into the aquitard located at the bottom of the shallowest aquifer. This slurry wall also increases efficiency of the groundwater extraction and treatment measures.

Vertical containment of the contaminants was achieved by groundwater extraction, so that there was a continual upward flux of groundwater through the site. Extracted groundwater was then treated to remove the contaminants, with the treated groundwater discharged to the local sewer system. In 1999, an impermeable RCRA cap was placed over the main containment area. By eliminating most of the precipitation from infiltrating into the containment area, it was easier to maintain an upward movement of groundwater through the area, and possible to use a slower rate of groundwater extraction.

Entire Site:
In addition to the removal actions, stormwater control, containment and extraction measures identified above, the remedy selected by EPA involved the following elements:
• an extensive soil and subsurface waste sampling program, on and off site property;
• excavation of hot-spots of soil within the containment area,
• operation and maintenance of the groundwater extraction and treatment facility,
• excavation of contaminated Mill Creek and East Drain sediments;
• long-term surface water and groundwater monitoring;
• remediation of an offsite plume of 1,2-dichloroethene located west of Mill Creek, and
• institutional controls to protect the remedy, such as deed restrictions, as necessary.

Cleanup since the initial removal actions have been performed by the Responsible Parties under a Consent Decree with EPA. Surface water quality goals for Mill Creek were attained in 1990, which was followed with the cleanup of contaminated sediments in Mill Creek and the East Drain in 1994. Extensive monitoring, including sampling of the extraction wells, treatment plant influent and effluent, and Mill Creek and the East Drain, is continuing.

Groundwater in the area of the offsite plume was extracted and treated between October 1988 and April 2000. Site conditions are conducive for natural attenuation of the remaining offsite contamination, so a monitored natural attenuation program was implemented on April 2000 and only trace concentrations have been detected in recent monitoring events. Monitoring results show that the contaminants biodegraded as predicted. The area will continue to be monitored until cleanup standards have been met.

Long-term Actions:
Groundwater within the containment area will continue to be pumped and treated until all established cleanup goals have been met. Most of the institutional controls are in place but some of the required controls, such as deed restrictions, still need to be implemented in order to ensure the long term protection of the remedy. In March 2000, EPA, the Western Processing Trust, and the Washington Department of Ecology celebrated the conclusion of the active phase of cleanup work at Western Processing. At that time, many significant cleanup milestones had been accomplished over the previous 15 years of work, including a 95% reduction in groundwater pollutant levels.

The remedy for the Western Processing site is currently protective of human health and the environment because the contaminated groundwater and soil in the source area are contained by the slurry wall, the RCRA cap and the containment pumping and treatment system. Offsite contaminants have declined to the point that concentrations of groundwater contaminants in the affected area are frequently below quantification limits at this time. There is no current exposure pathway to the offsite groundwater contaminants. However, for the remedy to be protective in the long term, institutional controls that will run with the land need to be placed on the property to protect the containment cell. EPA and the Western Processing Trust are working to resolve this issue.

Recent Updates:
Site visits and reviews of the operations and monitoring data are done twice per year. The last review took place on 8 December 2011. All operations were considered to be satisfactory and all systems were operating normally. The next review is scheduled on 14 June 2012.

The site was inspected on 3 April 2008 to assess the protectiveness of the remedy, including the condition of the extraction and treatment system, condition of the cap and cover, stormwater control, and security fencing. That inspection found:
1. The Western Processing site remained fenced with access controlled by onsite personnel.
2. The RCRA cap and drainage system appeared to be properly maintained and functioning as designed.
3. The site groundwater extraction system operated continuously with only very brief shut-downs for a brief outage in March 2007 and routine maintenance.
4. During 2007, the treatment plant processed 3.38 million gallons of water, and extracted 2.9 pounds of zinc, 0.2 pounds of chromium, and 44.7 pounds of volatile organic compounds (VOCs) from the water before discharge.
5. Documentation verifies that the treatment plant remains in compliance with the King County water discharge requirements.
(The site currently operates under King County Major Discharge Authorization No. 4111-01.)
6. Piezometers are a necessary component for the monitoring system, have a limited lifespan, and were being replaced as necessary throughout the year.
The next full-site inspection will take place before August 2013

EPA performs a formal review of the site progress every five years to ensure that the remedy continues to protect human health and the environment. EPA completed its fourth Five-Year Review of the Western Processing Superfund site in July 2008; and determined that the site continues to protect human health and the environment. Copies of the complete assessment are available at: http://www.epa.gov/superfund/sites/fiveyear/f2008100002609.pdf

Howard Hanson Dam:
In the winter of 2009-2010, the Corps of Engineers minimized the amount of water retained by the Howard Hanson Dam due to a compromised embankment next to the dam. At that time, Engineers at the Corps projected a 1 in 3 risk of flooding in the Green River Valley; some of the worse case projections involved a partial flooding of the Western Processing site, along with the loss of power and sewer services. The Western Processing Trust has developed a flood mitigation plan to address this possibility, and was prepared to implement that plan if flooding occured. Due to work done by the Corps to stabilize the embankment up through May 2011, the Corps reduced their risk estimate of flooding in the Green River to 1 in 60.

72nd Ave. S.
The City of Kent plans to extend 72nd Ave. S. across the site, starting work sometime in 2012-2014.. The containment cell was constructed to withstand the load of an extended 72nd Ave S. on top of it. Some monitoring locations will change to accomodate the road and the contractors collecting groundwater samples. The Western Processing Trust is coordinating these activities with the City of Kent.

Hide details for Regional ContactsRegional Contacts

SITE MANAGER(S):Chris Bellovary
E-MAIL ADDRESS:bellovary.chris@epa.gov
PHONE NUMBER:206-553-2723
E-MAIL ADDRESSsherbina.debra@epa.gov
PHONE NUMBER:206-553-0247
Information pertaining to this site is housed at the following location(s):
EPA Region 10 Superfund Records Center (Administrative Record)
1200 Sixth Avenue, Suite 900, ECL-076
Seattle, WA 98101