Congressional District # 06
WPSC MANITOWOC MGPEPA ID# WIN000509949
Last Updated: May, 2012
The WPSC Manitowoc former MGP site is located southeast of the Manitowoc River in Manitowoc, Wisconsin. Manufactured Gas Plants (MGPs) were industrial facilities that produced gas from coal, oil, and other feedstocks. The Manitowoc site totals about 5 acres in size, with about 4 acres on land and about 1.2 acres of potentially contaminated sediment found in an adjacent stretch of the river.
The Manitowoc site is located in an historically industrial area of the city. The majority of the site is currently occupied by actively used commercial buildings and asphalt parking lots. Residential, commercial, and industrial-use properties are also found in the vicinity.
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. Operation records are not complete, but the Manitowoc gas plant seems to have been operated from before 1900 to about 1947. 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 waste and spills and leaks often resulted in contaminated soil and groundwater. MGPs were often located near waterbodies and sediment contamination is also common.
Wisconsin Public Service Corporation (WPSC), an operating utility company, is a potentially responsible party for several former MGPs located throughout Wisconsin, including the Manitowoc site. WPSC is addressing six of its former MGP sites under the Superfund alternative site approach.
The WPSC Marinette 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 Manitowoc site soil cleanup was conducted on the most contaminated areas. However, soil at the site still contains residuals of polynuclear aromatic hydrocarbons (PAHs); volatile organic compounds (VOCs), especially a group of VOCs called benzene, toluene, ethylbenzene, and xylene (BTEX); and cyanide. Groundwater flows generally from beneath the site towards the Manitowoc River. Groundwater contamination includes PAHs; cyanide; naphthalene; benzo(a)pyrene; trimethylbenzene; and BTEX. Free product (DNAPL) is routinely found in an area near the southwest corner of one of the buildings. Sediment in the nearby Manitowoc River contains PAHs and BTEX, and shows evidence of odor, sheen and/or tar associated with MGP waste. Visible sheens have been observed in surface water near the site.
People could be exposed to MGP wastes at the Manitowoc 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, exposure to MGP wastes is limited by the asphalt parking lots and commercial buildings covering the remains of the contaminated soil and because drinking water is supplied by the city.
WPSC and EPA entered a settlement agreement in May 2006 to address site conditions at six former MGP sites in Wisconsin, including the Manitowoc site. Under the agreement, WPSC has agreed to conduct remedial investigations and feasibility studies at the 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.
Under the state program various investigations of the Manitowoc site have occurred since 1988. Some upland cleanup occured between 1992 to 1994 when highly contaminated soil between the WPSC building and the Manitowoc River was excavated and removed from the site or treated in place by stabilization. Routine groundwater monitoring occurs annually. In 1997 a single extraction well and treatment system were installed to address the free product (DNAPL) found in groundwater.
Additional investigation of remaining contamination will occur under the enforcement agreement with EPA. Field sampling to delineate the remaining contamination at the old MGP site and in the Manitowoc River began in 2008 and will continue through late 2012.
ContactsRemedial Project Manager, U.S. EPA
margaret gielniewski (email@example.com)