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Congressional District # 01


EPA ID# WID980820062
Last Updated: February, 2014

Site Description

The Delavan Municipal Well #4 ("Well #4") Superfund site is located in Delevan, Walworth County, Wisconsin.  The Well #4 site is defined as the contaminated aquifer used by Delevan's Municipal Well #4. 

There are more than 3,000 people living within one mile of the site. The population of Delavan relies on municipal water, and no private wells have been identified in the area. Surrounding the site are schools, homes, businesses, and an industrial facility.  The distance from Well #4 to the closest residence is 500 feet.

Well #4 was closed in 1982 due to discovery of contamination by volatile organic compounds (VOCs).  Since 1993, water pumped from Well #4 has been treated by an air-stripping tower and the effluent is then blended in a reservoir with water from two other wells prior to being pumped to the municipal water distribution system.   The treatment ensures that concentrations of contaminants entering the water distribution system are consistently below levels that are considered a health risk.


Site Responsibility

The Well #4 site is being addressed through federal, state, and potentially responsible party (PRP) actions.

Threats and Contaminants

The aquifer from which Well #4 draws water is contaminated with VOCs.  People could be exposed to VOCs by drinking or bathing with contaminated water.  However, untreated water currently does not exceed federal maximum contaminant levels (MCLs) under the Safe Drinking Water Act.

A cleanup remedy was installed at the site, which consists of an extraction well and groundwater aeration system that discharges VOCs to the atmosphere.  Emissions are monitored regularly in accordance with an air emission permit.  The discharge does exceed permitted conditions.

Cleanup Progress

A potentially responsible party (PRP) for the site contamination has taken steps to contain contaminated groundwater near the site through the installation of a groundwater extraction system and a soil venting system. While the systems had been operational for years, investigative work had shown that expansion was necessary. The groundwater extraction and soil venting systems were expanded in 1992. In January 1993, a focused feasibility study for interim remedial measures was approved which called for the construction of an expanded soil vapor extraction and groundwater extraction system (SVE/GWE).

The SVE/GWE system was constructed by the PRP and went online on June 16, 1994. The extraction system controls three source areas on the responsible party's property. The SVE segment of the project is removing VOCs at the rate of 26 lbs/yr. The groundwater quality has improved considerably since the system was constructed. VOC concentrations in nearly all monitoring wells have decreased significantly since the system has been put online.

In September 2000, EPA signed a Record of Decision to select continuation of the operation of the interim remedial measure (see above) as the final remedial measure.  As long as the interim remedial measure continues to operate successfully, no further action will be necessary.

EPA completed a five-year review (FYR) at the site in September 2000 and determined that the remedy was protective of human health and the environment.  The second FYR was completed in September 2010 and EPA determined that the remedy at the site remained protective.  EPA plans to complete third FYR by August 2015.



Remedial Project Manager, U.S. EPA
colleen moynihan (moynihan.colleen@epa.gov)
(312) 353-8196





Site Profile Information

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


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