WIN000509983, Superfund Alternative Approach Agreements Sites | Region 5 Superfund

U.S. EPA REGION 5
PORTAGE COUNTY
STEVENS POINT

Congressional District # 07

WPSC STEVENS POINT

EPA ID# WIN000509983
Last Updated: May, 2008

Site Description

The WPSC Stevens Point MGP site is located in Stevens Point, Wisconsin. Wisconsin Public Service Corporation (WPSC), an operating utility company, is responsible for several former manufactured gas plants (MGPs) throughout Wisconsin. The Stevens Point site is about 3 acres in size, with additional areas of contaminated sediment in a pond in the adjacent Pioneer Park and in the nearby Wisconsin River. The Stevens Point site is located in an historically industrial area, which included lumber operations. The gas plant operated from about the 1890s to the late 1940s. The site is bounded to the west by Pioneer Park, a public park owned by the City of Stevens Point. Beyond the park further west is the Wisconsin River. During operations a fomer slough ran adjacent to the site into what is now the park and toward the river. The site is currently open space owned by WPSC.

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 Stevens Point site soil cleanup was conducted on the most contaminated areas in 1998. However, soil at the site still contains residuals of polynuclear aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs) including a group of VOCs called benzene, toluene, ethylbenzene, and xylene (BTEX), lead, and cyanide. Groundwater at the site generally flows west, away from the Wisconsin River because the site is upstream of the Main Street Dam. Groundwater contamination includes PAHs, cyanide, BTEX, and lead. Sediment in the small pond in Pioneer Park contains PAHs and the nearby Wisconsin River sediment, particularly near the slough, contains PAHs and BTEX, and shows evidence of odor, sheen or tar associated with MGP waste.

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 Stevens Point site have occurred since the 1990s. In 1998, upland cleanup occurred including excavation and thermal treatment of about 16,400 tons of highly contaminated soil and placement of clean soil cover. Routine groundwater monitoring occurs quarterly for some wells and semi-annually for others. Additional investigation of remaining contamination will occur under the enforcement agreement with EPA. Investigation planning started in 2006, and field work was completed in 2007. The results of the investigation will be reviewed to determine areas that may need additional cleanup.

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