Congressional District # 07
WPSC STEVENS POINTEPA ID# WIN000509983
Last Updated: August, 2013
The 3-acre WPSC Stevens Point MGP site is located next to Pioneer Park and near the Wisconsin River in an historically industrial area of Stevens Point, Wisconsin. The site is currently open space owned by the Wisconsin Public Service Corporation (WPSC), an operating utility company. The gas plant was operated from about the 1890s to the late 1940s. During operations, a former slough ran adjacent to the site and carried site wastes into what is now the park and toward the river. The waste from the site has contaminated sediment in a small pond in Pioneer Park and in the river.
Manufactured Gas Plants (MGPs) were industrial facilities that produced gas from coal, oil, and other feedstocks. MGPs began 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 facility: coal carbonization and carbureted water gas. Both processes produced waste and by-products such as tars, purifier waste, oils, sludges, and acidic waste. On-site disposal of waste and spills and leaks often resulted in contaminated soil and groundwater. MGPs were often located near waterbodies and thus sediment contamination is also common.
WPSC is responsible for several former MGP sites throughout Wisconsin.
The Stevens Point MGP site is being addressed by the potentially responsible party (PRP) under state and federal oversight.
Threats and Contaminants
WPSC conducted a soil cleanup action at the site in 1998 that concentrated on the more highly contaminated areas. However, soil at the site still contains residual amounts 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.
WPSC and EPA entered a settlement agreement in May 2006. Under the 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.
Previously under the state program, WPSC had conducted various investigations at the Stevens Point site since the 1990s. In 1998, WPSC cleaned up soil in the upland area, which included the excavation and thermal treatment of about 16,400 tons of highly contaminated soil and placement of clean soil cover. Routine groundwater monitoring was conducted on a quarterly to semi-annual basis.
Additional investigation of remaining contamination is now occuring under the enforcement agreement with EPA. Investigation planning started in 2006, and the first round of field work was completed in 2007. Additional field work was initiated in January 2011, and revisions to the remedial investigation and feasibility study (RI/FS) were submitted in May and December 2011. EPA approved the revised RI/FS Report in May 2012, and in June announced a proposed cleanup plan that consisted of the placement of institutional controls on the property to restrict access to contaminated soil and groundwater, the monitoring of the natural attenuation of contaminated groundwater, dredging contaminated river sediment, and covering the contaminated pond sediment. EPA signed a Record of Decision selecting this remedy in September 2012, and, in May 2013, the agency and WPSC entered into an enforcement agreement under which WPSC would complete the remedial design. EPA plans to negotiate with the PRP to sign a Consent Decree by April 2014 under which the PRP would perform the selected remedial action.
ContactsRemedial Project Manager, U.S. EPA
leslie patterson (email@example.com)