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Congressional District # 06


EPA ID# WID006100275
Last Updated: November, 2014

Site Description

The Oconomowoc Electroplating Company Inc. (OECI) Site was once an electroplating facility located at 2572 West Oak Street, in Ashippun, Wisconsin. The 10-acre OECI Site comprises 4-acres formerly occupied by the OECI facility (bounded by Elm, Oak, and Eva Streets, and the Town of Ashippun’s municipal garage), and 6 acres of adjacent wetland located to the southwest. Davy Creek flows through the adjacent wetland approximately 500 feet south of the treatment facility. The area immediately surrounding the OECI Site is a mixture of light industrial, commercial, municipal, and residential parcels. There is no municipal water supply, and the residents and businesses rely on groundwater from individual wells for their drinking water.

Site Responsibility

This site is being addressed through federal and state actions. The Remedial Action at the OECI Site was federally financed because the only identified Potentially Responsible Party formally declined to participate in the CERCLA process. Federal regulations allow federally financed remedial actions to proceed for a period of up to ten years after the remedy becomes Operational and Functional (O&F). EPA defines the ten year period between the O&F determination and the start of Operation and Maintenance (O&M) as a long-term response action (LTRA). After the ten year LTRA, federal regulations provide the statutory basis for the transfer of federally financed ground water and surface water restoration projects from an EPA directed LTRA to a State directed O&M program. The OECI Site was deemed O&F on May 7, 1999; the ten year LTRA expired May 7, 2009.

The transfer of the OECI Site to a State led O&M program was delayed by the shutdown of the groundwater extraction and treatment system in 2004, which necessitated formally amending the ROD. The ROD was amended in May 2011, and the selected remedy for OU-3 was changed from groundwater extraction and treatment to source area removal or in situ treatment and MNA. Subsequent to the ROD amendment, EPA completed the in situ treatment of residual source areas at the site, and responsibility for O&M at the site was oficially transferred to the State in October 2014.

Threats and Contaminants

The OECI facility began operating in 1957. The plating processes used nickel, chrome, zinc, copper, brass, cadmium, and tin. Contamination associated with the OECI Site originated from spent process solutions, the transfer of material from processing baths to rinses, accidental spills, leaks, plating tank filter systems, and sludge from plating baths. Wastewater from the OECI facility contained cyanide compounds, chromium compounds, and acid-alkaline solutions. In addition, degreasing operations also contributed volatile organic compounds (VOCs) to the waste stream. The VOCs that were used by OECI include chloroform, 1-1-dichloroethane, 1-2 dichloroethane, 1,1-dichloroethylene, tetrachloroethylene, 1,1,1-trichloroethane, and trichloroethylene.

Prior to 1972, untreated wastewater was discharged directly into the wetland area south of the OECI property. In 1973 OECI installed a wastewater treatment system, and the Wisconsin Department of Natural Resources (WDNR) issued a Wisconsin Pollution Discharge Elimination System (WPDES) permit for discharges to Davy Creek. OECI also constructed two unlined settling lagoons to supplement their wastewater treatment system. Over the years, both lagoons accumulated large volumes of plating sludge and supernatant, which overflowed the lagoons and accumulated in the wetlands between the OECI facility and Davy Creek.  

Electroplating activities and careless waste management at OECI contaminated groundwater, wetland and creek sediments, and subsurface soils with cyanide, VOCs, and heavy metals, including chromium, cadmium, copper, nickel, and zinc. Ingesting, inhaling, or coming into direct contact with the contaminated soil, groundwater, or creek sediments may cause a potential health threat. These contaminants also threaten aquatic organisms in the wetland and creek sediments, and could bioaccumulate, possibly posing a threat to anyone consuming those organisms. 

Cleanup Progress

In 1990 EPA issued a Record of Decision (ROD) that identified four Operable Units (OUs) at the site: OU-1, surface water, metal hydroxide sludge and contaminated soils associated with the two RCRA Subtitle C lagoons located behind the OECI facility; OU-2, contaminated soil around the OECI facility not associated with the RCRA lagoons; OU-3, contaminated groundwater associated with the site; and OU-4, the most highly contaminated sediments in Davy Creek and the wetlands area. A 1991 Explanation of Significant Differences (ESD) added a fifth operable unit (OU-5) to provide for dismantling the abandoned facility and disposing of associated debris, and a 1994 ESD addressed the final cleanup for the adjacent wetlands and Davy Creek.

The remedial actions carried out under the 1990 ROD and two subsequent ESDs comprised multiple removal operations to eliminate the source of contamination from the site. These included:

• Excavation and disposal of the lagoon sludge and surrounding soils
• Excavation and disposal of non-lagoon contaminated soil and debris from the site
• Excavation and disposal of sediments contaminated with metals from the wetlands adjacent to Davy Creek

These source removal activities were successfully completed during the early to mid 1990’s. In addition to the remedial actions that addressed OU-1, OU-2, OU-4, and OU-5, the 1990 ROD also required the extraction and treatment of contaminated groundwater from OU-3 to restore conditions to Wisconsin groundwater quality standards, and a groundwater extraction and treatment system was built in 1996.

EPA evaluated the performance of the groundwater extraction and treatment system in 2000 and 2004, and concluded that it had essentially eliminated the environmental and human health threats posed by heavy metals in groundwater, but the high organic carbon content of the silty sand in the water table aquifer creates a reservoir of TCE that is sorbed to the soil, constituting a source that could persist for decades, limiting both the migration of TCE away from source area and the ability to remediate the site through pumping and treating the groundwater. EPA authorized the shutdown of the treatment plant in July 2004.

EPA amended the 1990 ROD on May 16, 2011, changing the remedy for OU-3 from extraction and treatment to source area removal or in situ treatment and Monitored Natural Attenuation (natural attenuation refers to inherent subsurface processes including volatilization, dispersion, adsorption, and biodegradation). Given the residual source material’s resistance to extraction, EPA’s revised strategy for completing the remedial action focuses on removing or treating the residual source material, allowing natural attenuation to remove VOCs from the contaminant plume until remedial standards are achieved, and monitoring groundwater to ensure protectiveness and assess the degree of natural attenuation that is occurring.

The most recent Five-Year Review (FYR) was completed in July 2012.  The 2012 FYR concluded that the remedy is currently protective of human health and the environment in the short term. The removal of lagoon sludge, contaminated soil, contaminated sediment, former facility, and associated debris has achieved the remedial action objectives of minimizing the migration of contaminants to groundwater and surface water and preventing ingestion or direct contact with contaminated media. The next FYR will be completed before July 11, 2017.

Property Reuse

The Town of Ashippun has expressed an interest in using the building that houses the groundwater treatment facility and the adjacent parking area for storing fire and maintenance equipment, and a local business has also expressed an interest in obtaining the building for light manufacturing. Part of the amended remedy included ensuring that the treatment plant is suitable for transfer. This has been completed. The site’s location adjacent to a wetland and between two ball fields would also support recreational use, but deed restrictions must be impleted before any reuse can be allowed.


Remedial Project Manager, U.S. EPA
william ryan (ryan.williamj@epa.gov)
(312) 353-4374

Community Involvement Coordinator, U.S. EPA
susan pastor
(312) 353-1325




Site Profile Information

This profile provides you with information on EPA's cleanup progress at this Superfund site.


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