Congressional District # 06
HECHIMOVICH SANITARY LANDFILLEPA ID# WID052906088
Last Updated: September, 2011
The Hechimovich Sanitary Landfill site is situated on 24 acres and is located in Williamstown, Wisconsin, a rural area, located approximately two miles south of Mayville. The site is a former municipal and industrial waste landfill that operated under different ownerships from about 1959 to 1986. For a period of time the site was licensed to accept hazardous waste and the site did receive liquid industrial wastes that were placed in unlined pits. Some of the types of wastes disposed in these pits included paint sludges, cutting oils, and spent organic solvents. The Wisconsin Department of Natural Resources (WDNR) required the pits to be closed in 1980.
The U.S. Environmental Protection Agency (EPA) detected volatile organic compounds (VOCs) in two wells downgradient of the site in 1984. During operations, the owner of the site violated the terms of the landfill's operating license by depositing solid waste in areas beyond those previously approved by WDNR. This violation was the subject of a state enforcement action in July 1987.
EPA proposed the site for inclusion on the National Priorities List (NPL) in June 1988 and finalized the site on the NPL in March 1989.
The towns nearest to the site are Mayville with 4,330 residents and Horicon with 3,585 residents. Approximately 5,000 people obtain their drinking water from private wells located within three miles of the site.
Site ResponsibilityThis site is being addressed through federal, state, and potentially responsible party (PRP) actions.
Threats and ContaminantsGroundwater in several monitoring wells downgradient of the site is contaminated with VOCs in excess of state groundwater quality standards. In addition, two residential water supply wells are contaminated with VOCs in excess of state drinking water criteria. On-site soil is also contaminated with VOCs. Direct contact with or ingestion of contaminated groundwater or soil may pose health threats. Local surface waters may be used by residents for recreational activities. If site-related contaminants should migrate into the surface water, residents could be exposed to them when coming into direct contact with these bodies of water. Directly north of the Hechimovich Landfill site is a wetland which could be at risk from site runoff.
Through the enforcement of an existing state court order, the PRPs installed a landfill cap and a gas collection system at the site. Because of the success of the initial actions, WDNR determined in a January 1994 Record of Decision (ROD) that no further source control action was necessary. EPA concurred on the ROD.
The PRPs completed studies to determine the nature and extent of groundwater contamination in 1994. WDNR selected a final remedy for the groundwater in a September 1995 ROD. The selected action was to continue with the source control actions and determine, through long-term groundwater monitoring, if those actions will remediate the groundwater contamination. Should the groundwater contamination not be remediated by the source control actions, the selected remedy will be revised through a decision amendment to require further actions.
The first five-year review for the site was completed in February 1999 and the second review was completed in June 2004. In June 2009, EPA signed the Third Five-Year Review Report for the site. The 2009 five-year review, which was prepared by WDNR, found that the remedy is protective of human health and the environment in the short-term, but identified issues that needed to be addressed.
As discussed in the 2009 five-year review, the understanding of site conditions dramatically changed in the spring of 2009. Based on ongoing site investigations it seems probable that waste disposal activities at the landfill property are a source of drinking water contamination in several private drinking water wells located about 1800-4000 feet northeast of the waste boundary. Two of these wells have vinyl chloride concentrations exceeding state and federal drinking water maximum contaminant levels. In addition, one of these drinking water wells has a vinyl chloride concentration high enough to make the water unusable for any domestic purposes. This drinking water contamination lies deep within the bedrock aquifers downgradient, northeast, of the site. It is now understood that there is a deeper, previously unknown, groundwater contaminant plume leaving the landfill property to the northeast, moving through various bedrock units and impacting private drinking water wells cased 180-190 feet below the ground surface. Based on the current site conceptual model, it seems likely that the source of the bedrock contamination was a dense non-aqueous phase liquid (DNAPL) lying on top of the shale. This DNAPL is now likely dissipated and not amenable to any practical remedial measures. Because the source of the bedrock contamination can not be addressed through an active remedial measure, future response actions at the site will involve primarily monitoring and mitigation of current and future water supply impacts.
As an interim public health protection measure, bottled drinking water has been provided to the two homes with contaminant levels exceeding drinking water standards. One of the homes which was a rental unit has been vacated. A permanent water supply solution for the second home will involve either a new well or treatment system on the existing well.
ContactsRemedial Project Manager, U.S. EPA
sheila desai (firstname.lastname@example.org)
Community Involvement Coordinator, U.S. EPA
HECHIMOVICH SANINTARY LANDFILL
HECHIMOVICH SAN LDFL