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Congressional District # 08


EPA ID# MND980904064
Last Updated: December, 2012

Site Description

The 212-acre Ritari Post & Pole site is located approximately 3.5 miles northeast of the town of Sebeka (population: 775) in a rural area of Wadena County, Minnesota,  The site was the location of a wood-preserving facility that operated from 1959 to 1991. The wood-preserving operation used creosote as a preservative until 1966, and following that, used pentachlorophenol (PCP) as a preservative.  From 1966 to 1973, the site used a process that allowed approximately 72,000 gallons of PCP to drip from treated wood directly onto the ground.  In addition, approximately 3,200 gallons of PCP-contaminated sludge were discharged directly to the ground.  About 350 people live within three miles of the site.  The site is located three-quarters mile from a wetland area which drains to the Cat River. 

Site Responsibility

The Minnesota Pollution Control Agency is the lead agency which managed cleanup of the site and continues to oversee the site.  

Threats and Contaminants

Soils at the site were contaminated with PCP, dioxins and furans.  Groundwater at the site was contaminated with PCP and various petroleum compounds which were used as carriers for PCP in the wood treating process. 

Cleanup Progress

This site was addressed as a state lead cleanup.  The Minnesota Pollution Control Agency (MPCA) completed an investigation into the nature and extent of contamination at the Site and in 1994, MPCA and EPA selected a remedy for contaminated soil and groundwater.  The soil remedy included excavation and stockpiling of contaminated soils using an action level of 40 ppm PCP and 1 ppb dioxin (tetrachlorobenzodioxin (TCDD)-equivalent).  For PCP-contaminated soils, the remedy required on-site bioremediation in a lined treatment cell.  For dioxin-contaminated soil, the remedy required investigation of soil washing as a treatment technology and off-site incineration of remaining dioxin-contaminated soil.  The soil remedy for both types of contaminated soil also included a contingency to require consolidation and disposal with a RCRA-compliant cap if treatment studies or actual treatment for three years indicated that soil cleanup standards would not be met. 

In 1999, MPCA and EPA modified the soil remedy in an Explanation of Significant Difference (ESD) to remove soil treatment and incineration from the remedy and invoke the contingency for on-site containment covered by a RCRA-compliant cap.  In 2008, the State and EPA modified the remedy for dioxin-contaminated soil to require excavation and off-site disposal.  Therefore, the final soil remedy included an on-site disposal unit with a RCRA cap and excavation and off-site disposal of additional soils. 

The 1994 groundwater remedy included installing an on-site water supply well and groundwater monitoring.  The groundwater remedy also included a contingency to require extraction and treatment if groundwater contaminants exceeded certain levels at the eastern boundary of the site.  In the 1999 ESD, the State and EPA determined that it would not be necessary to invoke the contingent remedy for groundwater and that groundwater monitoring would be sufficient.  Beyond the property line, the monitoring wells and a private well showed no detection of contamination.

In 1997, EPA and MPCA removed 38 deteriorating drums, containing spent PCP solution.  This allowed MPCA to decontaminate and move or  dismantle certain onsite buildings in preparation for further cleanup.  Installation of onsite and offsite monitoring wells and a deeper domestic well for the onsite household were also completed in 1997.  Contaminated soils were placed in an on-site, unlined capped cell, for which construction was completed in 2001.  A Preliminary Close Out Report (PCOR) was completed in 2001.  Maintenance of the onsite capped unit and groundwater monitoring are being performed by MPCA and its contractors. 

Five year reviews are conducted at the site.  The last review occured in 2008 and concluded that the remedy was functioning as intended and is protective of human health and the environment in the shortterm, but that certain actions were needed to ensure longterm protectiveness.  These actions included evaluation of an additional soil area known as Area A, evaluation of potential groundwater flow to the northeast, and evaluation of institutional controls.  These actions are ongoing at the site as part of the upcoming five-year review which will be completed in 2013.   




Remedial Project Manager, U.S. EPA
leah evison (evison.leah@epa.gov)
(312) 886-2064

Community Involvement Coordinator, U.S. EPA
heriberto leon
(312) 886-6163

Site Profile Information

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


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