LA PRAIRIE TOWNSHIP
Congressional District # 01
WHEELER PITEPA ID# WID980610620
Last Updated: November, 2011
Site DescriptionThe 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. T he 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' 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.
Under a unilateral administrative order (UAO), GMC undertook 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. The remedy addressed groundwater contaminants such as iron, manganese, chromium and arsenic and cadmium and lead in soils. Construction was completed in 1992, and the operation and maintenance phase began in 1993. Groundwater has been monitored since 1992, and 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, has confirmed that groundwater contaminants at the site have 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 Five-Year Review 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. The site was subsequently delisted from the National Priorities List (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. As part of a nationwide ongoing evaluation of long-term monitoring at deleted Superfund sites, OIG sampled PW-3 in May 2008. In September 2010, OIG completed an Evaluation Report for the Site and recommended that EPA region 5 take corrective action by conducting additional sampling of the residential well with excess levels of the chemical compound di(2-ethylhexyl)phthalate (DEHP) to verify the Region's assertion that DEHP is originating from the sampling process. The August 2011 samples taken by Region 5 at PW-3, along with 12 additional on-site and off-site wells, did not detect DEHP with the exception of method blank samples. Therefore, Region 5's recent sampling results confirm that DEHP does not exist at the site above the federal or state drinking water standards. EPA provided documentation of our recent findings to OIG to close out the audit, and to the resident. The next Five-Year Review is scheduled in 2012.
ContactsRemedial Project Manager, U.S. EPA
Karen Mason-Smith (email@example.com)
Community Involvement Coordinator, U.S. EPA