LA PRAIRIE TOWNSHIP
Congressional District # 01
WHEELER PITEPA ID# WID980610620
Last Updated: May, 2015
The Wheeler Pit site, located in Rock County, Wisconsin, is a 3.82-acre former disposal area. It lies within a 35-acre abandoned gravel pit. Wheeler Pit originally was mined for sand and gravel by the Chicago, Milwaukee, St. Paul, and Pacific Railroad company. In 1956, General Motors Corporation (GMC) leased a four-acre portion of the pit from the railroad for waste disposal. From 1960 to 1974, GMC used Wheeler Pit to dispose of paint and waste water sludges from its Janesville auto assembly plant as well as coal ashes from power plant boilers. The sludge and ash were contained by a dike at the pit. In 1971, a liquid was found seeping on the ground from the GMC disposal area. Disposal at Wheeler Pit ceased in 1974, and the site was covered at the request of La Prairie Township. From 1974 to 1988, the site was monitored intermittently for groundwater contamination. Approximately 51,000 people live within three miles of the site. The Rock River is approximately two miles west of the site. The city of Janesville operates five groundwater wells within three miles of the site. Three of the wells supply virtually all of the Janesville water supply. Five private wells are located within one-quarter mile of the site.
Site ResponsibilityThis site is being addressed through federal, state, and potentially responsible parties' (PRPs) actions.
Threats and ContaminantsElevated levels of the volatile organic compounds (VOCs), trichloroethylene (TCE), chromium, zinc, arsenic, and barium were found in site groundwater samples collected in 1981 by GMC and the Wisconsin Department of Natural Resources (WDNR). Groundwater resources, underlying the site, were found to be contaminated with heavy metals, including iron, manganese, chromium, and arsenic as well as low levels of VOCs. Soils and surface wastes contain heavy metals such as cadmium and lead and semi-VOCs.
The Site was placed on the National Priorities List (NPL) in September 1984. An investigation and study was conducted during 1987 through 1990, to determine the nature and extent of contamination at the Site. The investigation determined that the human health risks posed by contaminants warranted a federal response action. Under a unilateral administrative order (UAO) in May 1991, EPA required GMC to undertake the design and construction of the remedy at the site. The remedy consisted of construction of a multilayer cap, installation of a fence around the site to restrict access, consolidation of 36,400 cubic yards of waste and soil from neighboring property into the original disposal area, long-term groundwater monitoring, institutional controls of groundwater and land use on the site, and natural attenuation of the contaminated groundwater. Construction was completed in 1992, and the operation and maintenance (O&M) phase began in 1993 at the Site. Groundwater had been monitored at the Site since 1992.
In April 1997, a Five-Year Review was performed to evaluate the protectiveness of the site remedy. A 1998 Five-Year Groundwater Assessment Report, prepared by GMC, confirmed that groundwater contaminants at the site had decreased to below the Wisconsin Preventive Action Limits (PALs) except for one contaminant, manganese. A second Five-Year Review was completed in fall 2002 which determined that the site remedy was protective of human health and the environment. The second Five-Year Review also recommended that an explanation of significant differences (ESD) be prepared to delete manganese from the site contaminants of concern. An ESD was issued in summer 2003. Since groundwater cleanup goals have been achieved at the Site, Wheeler Pit was deleted from the NPL on April 20, 2004. A third Five-Year Review was completed in September 2007, and determined that the remedy was protective of human health and the environment in the short-term. However, long-term protectiveness at the site requires that a mechanism be developed to regularly monitor existing groundwater and land use restrictions to ensure that these restrictions remain effective.
EPA collected groundwater samples from a residential private well (PW-3) on August 9, 2011, and completed data validation efforts on August 26, 2011. This effort was in response to an Office of Inspector General (OIG) audit. The August 2011 samples taken by Region 5 at PW-3, along with 12 additional on-site and off-site wells, did not detect contaminants at the Site above the federal or state drinking water standards. EPA provided documentation of its findings to OIG to close out the audit, and to the resident. EPA also obtained a Title Commitment for the Site on March 25, 2011, and completed an evaluation of institutional controls (ICs) on April 20, 2012. The WDNR restarted O&M activities in August 2012, after the PRP (General Motors Corporation) stopped conducting O&M in 2008 and went bankrupt in 2009. The landfill cap is preventing direct contact with waste materials and minimizing the flow of water through the waste mass. Site use is consistent with current deed and land use restrictions. The fourth Five-Year Review for the Site was completed in September 2012, and found that the remedy is protective of human health and the environment in the short-term. However, in order for the remedy to be protective in the long-term, O&M activities must be conducted, a review of the ICs are needed and ICs need to be optimized and/or recorded where necessary to ensure that the remedy continues to function as intended. Long-term protectiveness at the Site requires compliance with land and ground water use restrictions. Long-term stewardship and monitoring is necessary to ensure compliance with the use restrictions by maintaining and monitoring effective ICs and site remedy components. U.S. EPA is currently working with two PRPs/land owners and WDNR to update the ICs at the Site.
ContactsRemedial Project Manager, U.S. EPA
Karen Mason-Smith (firstname.lastname@example.org)
Community Involvement Coordinator, U.S. EPA