Region 5 Superfund

U.S. EPA REGION 5
WINNEBAGO COUNTY
OSHKOSH

Congressional District # 06

WPSC OSHKOSH MGP

EPA ID# WIN000509947
Last Updated: December, 2012

Site Description

The WPSC Oshkosh former MGP site is located north of the Upper Fox River, about 0.2 miles downstream of Lake Winnebago, in Oshkosh, Wisconsin.  Manufactured gas plants (MGPs) were industrial facilities that produced gas from coal, oil, and other feedstocks.  The Oshkosh MGP site totals about 12 acres in size, with about 7.6 acres on land and about 4.3 acres of potentially contaminated sediment found in an adjacent stretch of the river.

The Oshkosh MGP site is located in an historically industrial, commercial, and residential area of the city.  The city has owned the site since 2003 and has redeveloped it into a public park that includes an amphitheater and river walk.  Boat docking is desired along the shoreline to enable boaters to visit the park. 

MGPs started operating in the U.S. in the early 1800s, typically in urban areas where gas was needed for lighting, cooking, and heating.  The Oshkosh gas plant operated from 1869 to 1946.  Two gas production methods were used at the 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 these wastes and spills and leaks often resulted in contaminated soil and groundwater.  MGPs were often located near waterbodies and sediment contamination is common.

Wisconsin Public Service Corporation (WPSC), an operating utility company, is a potentially responsible party for several former MGPs located throughout Wisconsin, including the Oshkosh site. WPSC is addressing six of its former MGP sites under the Superfund alternative site approach.

Site Responsibility

The WPSC Oshkosh former MGP site is being addressed through potentially responsible party (PRP) actions under state and federal oversight.

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 in the nearby Upper Fox River contains PAHs.

People could be exposed to MGP wastes at the Oshkosh site by dermal contact with contaminated soil or river sediment or by drinking contaminated groundwater.  Benthic (bottom-dwelling) organisms could be exposed to sediment contaminants in the river.  Exposure to the MGP contaminants could cause toxic health effects.  However, because residents and nearby businesses use the city water supply for drinking, no one is drinking contaminated groundwater from the site.  Exposure to contaminated soil was limited through soil excavation.  Further remedial investigation is necessary to deduce and eliminate other exposure routes to MGP wastes.

Cleanup Progress

WPSC and EPA entered into a settlement agreement in May 2006 to address site conditions at six former MGP sites in Wisconsin, including the Oshkosh site.  Under the enforcement agreement, WPSC has agreed to conduct remedial investigations and feasibility studies at the six former MGP sites. Because the six sites have similar conditions and contaminants, and WPSC is a potentially responsible party (PRP) 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 address the worst problems first.

WPSC had conducted various investigations of the Oshkosh site under the state voluntary cleanup program since the 1990s.  In 2002, WPSC conducted cleanup actions that included source area excavation 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.

The remedial investigation at the Oshkosh site is planned to begin in 2014 in accordance with the enforcement agreement.

Community Involvement

The city of Oshkosh has developed the former MGP site into a public park.

Contacts

Remedial Project Manager, U.S. EPA
margaret gielniewski (gielniewski.margaret@epa.gov)
(312) 886-6244

 

Site Profile Information

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