Region 5 Superfund (SF)

U.S. EPA REGION 5
WASHINGTON COUNTY
LAKE ELMO

Congressional District # 06

WASHINGTON COUNTY LANDFILL

EPA ID# MND980704738
Last Updated: September, 2009

Site Description

The Washington County Landfill (WCL) is a municipal landfill that accepted municipal and industrial waste materials.  The WCL encompasses approximately 35 acres and, as of 2008, contains an estimated 1.9 million cubic yards of waste.  The solid waste is comprised of 73% residential wastes, 26% commercial wastes and 1% demolition wastes including waste from 3M Corporation (3M).  The WCL was listed on the United States Environmental Protection Agency’s (EPA’s) National Priorities List (NPL) in 1984 due to the groundwater being contaminated with volatile organic compounds (VOCs).  On October 24, 1984, the Minnesota Pollution Control Agency (MPCA) and Washington and Ramsey Counties (the Counties) agreed to a Response Order by Consent (Order). Pursuant to the Order, the Counties perform all necessary remedial actions (RAs).  An Administrative Order (AO) was issued by the EPA to the Counties on January 16, 1992, and amended on February 17, 1993, to continue the RAs.  In 1996, pursuant to the Minnesota Landfill Cleanup Act (MLCA), the MPCA and the EPA terminated the AO and put the WCL in long-term management under the Minnesota Pollution Control Agency’s (MPCA’s) Closed Landfill Program (CLP).  Once the WCL entered the CLP, EPA deleted the site from the NPL.  Through the MLCA, MPCA is responsible for the care of the WCL, including future clean-up actions, long-term operation and maintenance (O&M), and monitoring groundwater (GW) contamination and landfill gas.  The MPCA is also responsible for implementing land-use planning measures that minimize public exposure to the hazards from the WCL.

Site Responsibility

This site is being addressed through federal, state, county, and potentially responsible parties' actions.

Threats and Contaminants

In 1981, volatile organic compounds (VOCs) were detected in soil and groundwater on site.  In 1983-4, VOCs were detected in privite wells.  In 1992, soil was sampled at the landfill and methane was detected in explosive amounts.

Cleanup Progress

In 1975, the year that the WCL was closed, a 2 foot landfill cover was installed. In 1996, the cover was upgraded to current standard layers including: geomembrane, sand drainage layer, rooting zone, and topsoil with shallow rooted grasses.

In 1984, the Counties ordered the construction of monitoring wells and a gradient control well and sprayer system as part of the remedy for OU1 under the (Response Action Plan) RAP.  The one gradient control well, located near the south west corner of the WCL, was designed to extract up to 200 gallons per minute (gpm).  The extracted water then went through a spray irrigation area in the southeast portion of the WCL that consisted of an area of 1.9 acres with sandy soils.  This area was believed to be contained within the capture zone of the gradient control system; regardless, contamination migrated off-site into private wells and further remedial actions were required.

Contracts were awarded for construction of the water supply system and residential well abandonment on June 4, 1991.  Construction of the water supply system was initiated on June 25, 1991.  Connection of the 10 residences with drinking water advisories to the system was completed on December 31, 1992.  Connection of the remaining 71 residences was completed by June 1993.  All 81 residences now have a safe drinking water supply.

In the early 1990’s, there was a gas explosion due to faulty wiring and pressure build-up.  Fourteen extraction vents were installed in 1993 on the edge of the WCL (primarily at the western boundary) to capture methane migrating toward homes and municipal buildings and release it near the center of the WCL.  In 1996, MPCA decided to install an enclosed flare and active gas extraction system to burn the extracted methane instead of just having it released on-site. 

In 2004, the MPCA sampled for chemicals known as perfluorochemicals (PFCs) for the first time and found PFCs in on-site monitoring wells and also in some downgradient residential wells. At about this time, scientific studies had been performed documenting the risks from PFCs and improved laboratory detection limits now allowed better detection of PFCs.

Since 2005, the MPCA and the Minnesota Department of Health (MDH) have sampled 404 residential wells for PFCs.  One hundred residences have been placed on bottled because they were advised by MDH not to drink their water. The MPCA placed granular carbon filters on an additional 22 residences in 2006.

On May 22, 2007 the MPCA and 3M Corporation, agreed to a Consent Order under the Minnesota Environmental response and Liability Act (MERLA) on PFC contamination issues in Minnesota.  Further cleanup of the Washington County Landfill was included as part of the Consent Order.  The landfill will be dug-up and placed into triple-lined excavated boxes onsite. The triple lined boxes will prevent further escape of any contamination from the site.  Construction began in October 2008 and is estimated to take three years to complete.

Contacts

Remedial Project Manager, U.S. EPA
margaret gielniewski (gielniewski.margaret@epa.gov)
(312) 886-6244

Community Involvement Coordinator, U.S. EPA
Don De Blasio
(312) 886-9749

Aliases

WASHINGTON COUNTY LDFL

 

Site Profile Information

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