Region 5 Superfund (SF)

U.S. EPA REGION 5
LA CROSSE COUNTY
ONALASKA

Congressional District # 03

ONALASKA MUNICIPAL LANDFILL

EPA ID# WID980821656
Last Updated: April, 2008

Site Description

The Onalaska Municipal Landfill site consists of a seven-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 close by. 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. 

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 United States Environmental Protection Agency (U.S. EPA) in consultation with the state began a remedial investigation and feasibility study (RI/FS) in 1988. The RI/FS was completed in 1990, upon issuance of a cleanup decision by the agency. also called 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 construction of the cleanup remedy in 1993. The cleanup remedy was completed in July 1994 and 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; whereas, 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 shut down of the groundwater treatment system to study natural attenuation as an alternative to cleanup the remaining groundwater contamination. The system was shut down on November 26, 2001. The state took over the operation and maintenance of the site in June 2002. WDNR 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 five-year review was completed in 2003. It also determined that the remedy remains protective of human health and the environment.

The next five-year review is currently being undertaken.  It is scheduled for completion in July 2008.

Contacts

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

Community Involvement Coordinator, U.S. EPA
bri bill
(312) 353-6646

Aliases

ONALASKA MUNI LDFL

 

Site Profile Information

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