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Superfund Alternative Site For Wisconsin
WINNEBAGO COUNTY
OSHKOSH
Congressional District # 06
WPSC OSHKOSH MGP
EPA ID# WIN000509947Last Updated: February, 2007
Site Description
The WPSC Oshkosh MGP site is located in Oshkosh, Wisconsin. Wisconsin Public Service Corporation (WPSC), an operating utility company, is responsible for several former manufactured gas plants (MGPs) throughout Wisconsin. The Oshkosh site is about 7.6 acres in size, with approximately 4.3 additional acres of contaminated adjacent sediment in the nearby Upper Fox River. The Upper Fox River borders the site to the south and Lake Winnebago is located about 0.2 miles downstream. The Oshkosh site is located in an area that was historically industrial, commercial and residential. The gas plant operated from 1869 to 1946. Since 2003, the site has been owned by the City of Oshkosh and was redeveloped into a public park which includes an amphitheater and river walk. Boat docking is desired along the shoreline to enable boaters to visit the park.
MGPs were industrial facilities that produced gas from coal, oil, and other feedstocks. MGPs started operating in the U.S. in the early 1800s, typically in urban areas where gas was needed for lighting, cooking, and heating. Two gas production methods were used at the WPSC MGP facilities: coal carbonization and carbureted water gas. Both processes produced waste and by-products such as tars, purifier waste, oils, sludges, and acidic waste. Disposal of waste and spills and leaks often resulted in contaminated soil and groundwater. MGPs were often located near waterbodies and sediment contamination is also common.
Site Responsibility
This site is being addressed through federal and potentially responsible party actions. This is one of six former MGPs to be addressed by WPSC under the Superfund Alternative Sites approach.
Threats and Contaminants
Soil, groundwater and sediment at former MGPs are often contaminated. At the Oshkosh site soil cleanup was conducted on the most contaminated areas. However, soil at the site still contains residuals of polynuclear aromatic hydrocarbons (PAHs), a group of volatile organic compounds (VOCs) called benzene, toluene, ethylbenzene, and xylene (BTEX), lead, and cyanide. Shallow groundwater at the site flows south toward the Upper Fox River while bedrock groundwater appears to flow north, away from the river. Groundwater contamination includes PAHs, cyanide, and BTEX. Sediment is the nearby Upper Fox River contains PAHs.
Cleanup Progress
WPSC and EPA entered a settlement agreement in May 2006. Under this unique agreement, WPSC has agreed to conduct remedial investigations and feasibility studies at six former MGP sites located throughout Wisconsin. Because the six sites have similar conditions and contaminants, and WPSC is responsible for each, the agreement allows a streamlined approach to site investigation and remedy development. Some benefits of the agreement include the use of multi-site documents, a mechanism to review the adequacy of past work, and scheduling flexibility to allow progress on the worst problems first.
Under the state program various investigations of the Oshkosh site have occurred since the 1990s. In 2002, upland remediation was conducted that included source area excavavtion and thermal treatment of about 23,500 tons of contaminated soil; installation of a sheet pile containment barrier wall along the shoreline of the Upper Fox River; groundwater treatment and gradient control; and capping the site. Routine groundwater monitoring occurs annually. Additional investigation of remaining contamination will occur under the enforcement agreement with EPA.