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Congressional District # 03


EPA ID# WID980821656
Last Updated: September, 2011

Site Description

The Onalaska Municipal Landfill site consists of a 7-acre landfill situated on an 11-acre parcel of property adjacent to the Black River in the Town(ship) of Onalaska (population 4,000). The surrounding area is rural and consists primarily of agricultural lands, although several homes are located nearby. The landfill area was formerly a sand and gravel quarry before it was used as a municipal landfill. From 1969 to 1980, the Township of Onalaska operated the landfill, where municipal refuse was commingled with industrial solvents such as naphtha, toluene, and trichloroethene. 

EPA proposed the site for the National Priorities List (NPL) in September 1983 and finalized the site on the NPL in September 1984.

Site Responsibility

This site is being addressed through federal and state actions.

Threats and Contaminants

The solvents from the landfill have contaminated the groundwater beneath the site, causing the contamination of an adjacent homeowner's drinking water well that the town of Onalaska replaced in the early 1980s. A floating layer of hydrocarbons, which acts as a source of groundwater contamination, was found to be emanating from the landfill. 

Cleanup Progress

The U.S. Environmental Protection Agency (U.S. EPA), in consultation with the state, began a remedial investigation and feasibility study (RI/FS) at the site in 1988. The RI/FS was completed in 1990, upon issuance of a cleanup decision by the agency. In the decision document, known as a Record of Decision (ROD), U.S. EPA determined that construction of a landfill cover (cap), a groundwater extraction and treatment system, and a bioremediation system would be protective of human health and the environment.

U.S. EPA, in concert with the state, began constructing the cleanup remedy in 1993. The construction work was completed in July 1994 and was documented in a preliminary close-out report (PCOR). Operation of the groundwater extraction and treatment and the bioremediation systems commenced at that time. It was estimated that the bioremediation system would operate for about five years and that the groundwater extraction and treatment system would operate for a minimum of 10 years. After 10 years of operation, the control of the site would be turned over to the state.

To date, the groundwater extraction and treatment system has pumped out 1.8 billion gallons of water for treatment via air stripping, significantly reducing the levels of contaminants in the groundwater plume. Current data indicates that metals are the only contaminants above the cleanup standards.  The bioremediation system, which simply supplies oxygen (air) to the subsurface soil where the hydrocarbon layer exists, has reduced the concentrations of the hydrocarbons in the soils.  The bioremediation system was discontinued in 1998 after soil gas data showed that the system no longer contributed to the cleanup.

On November 13, 2001, U.S. EPA signed an explanation of significant differences (ESD) for the site. The ESD allows for the temporary shutdown of the groundwater treatment system to study natural attenuation as an alternative to clean up the remaining groundwater contamination. The groundwater treatment system was shut down on November 26, 2001. The state took over the operation and maintenance of the site in June 2002. The Wisconsin Department of Natural Resources is continuing the natural attenuation studies.

A five-year review was completed in 1998 and determined that the remedy was still protective of human health and the environment. The second and third five-year reviews, completed in 2003 and 2008, respectively, also determined that the remedy remains protective of human health and the environment. 

U.S. EPA and WDNR are currently evaluating the need to have additional long-term institutional controls placed on the landfill property. The agencies are also evaluating a potential change to the current remedy that would permanently shut down the pump and treat system that was implemented to clean up volatile organic compounds (VOCs).


Remedial Project Manager, U.S. EPA
demaree collier (collier.demaree@epa.gov)
(312) 886-0214

Community Involvement Coordinator, U.S. EPA
susan pastor
(312) 353-1325




Site Profile Information

This profile provides you with information on EPA's cleanup progress at this Superfund site.


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