Congressional District # 06
WPSC MANITOWOC MGPEPA ID# WIN000509949
Last Updated: March, 2015
The WPSC Manitowoc former MGP ("Manitowoc") site is located southeast of the Manitowoc River in Manitowoc, Wisconsin. 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 a historically industrial area of the city. The majority of the site is currently occupied by 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. Operational records are not complete, but the Manitowoc gas plant may have 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) 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 EPA's Superfund Alternative site program.
The WPSC Manitowoc 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 with polynuclear aromatic hydrocarbons (PAHs); volatile organic compounds (VOCs), especially the group of VOCs called benzene, toluene, ethylbenzene, and xylene (BTEX); and other compounds. WPSC had conducted a soil cleanup action at the Manitowoc site on the most contaminated areas. However, the soil has residual levels of PAHs, BTEX, and cyanide in it.
Groundwater flows generally from beneath the site towards the Manitowoc River. Groundwater contaminants include PAHs, especially naphthalene, benzo(a)pyrene, and trimethylbenzene; cyanide; and BTEX. An underground pool of free product is 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 and/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 waste in soil is limited by the asphalt parking lot and commercial buildings covering much of the contaminated area of the site. In addition, exposure to contaminated groundwater is limited 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 agreed to conduct remedial investigations and feasibility studies at each of the former MGP sites. Because the six MGP 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."
Various investigations of the Manitowoc site have occurred under the state voluntary cleanup program since 1988. Some upland cleanup actions occurred 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 pool of free product found in the site groundwater.
Field sampling to delineate the nature and extent of contamination at the old MGP site and in the Manitowoc River began in 2008. WPSC submitted a draft remedial investigation (RI) report in July 2014 for EPA review. WPSC will submit the feasibility study (FS), a report documenting the array of cleanup alternatives, to EPA in May 2015. EPA plans to complete its review of the RI and FS reports and then issue a proposed cleanup plan for public comment in October 2015. EPA will then issue a Record of Decision in 2016 to select the site cleanup remedy.
EPA conducted community interviews in Manitowoc in February 2012 and later released the Community Involvement Plan, which is a template for engaging the public in the Manitowoc MGP site cleanup efforts. The plan is available online and at the Manitowoc Public Library.
ContactsRemedial Project Manager, U.S. EPA
margaret gielniewski (firstname.lastname@example.org)