Jump to main content.


Congressional District # 08


EPA ID# MND980904064
Last Updated: November, 2011

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 applied 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, draining into the Cat River which serves as a recreational area. 

Site Responsibility

The Minnesota Pollution Control Agency is the lead agency which managed cleanup of the site.  

Threats and Contaminants

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

Cleanup Progress

This site is being addressed as a state lead, fund-financed cleanup. In 1994, the state completed an investigation into the nature and extent of contamination and selected a remedy for the Site.  The 1994 soil remedy included excavation and stockpiling of contaminated soils as separate PCP- and dioxin-contaminated soils using an action level of 40 ppm PCP and 1 ppb dioxin (tetrachlorobenzodioxin (TCDD)-equivalent); investigation of soil washing to potentially reduce the volume of dioxin-contaminated soils; off-site incineration of remaining dioxin-contaminated soil; on-site bioremediation in a lined treatment cell for PCP-contaminated soils to meet a treatment standard of 40 ppm PCP.  The soil remedy also included a contingency to require consolidation and disposal of PCP and dioxin-contaminated soils iwith a RCRA-compliant cap if treatment studies or actual treatment for 3 years indicated that soil cleanup standards would not be met. 

In 1999, the State 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 soil remedy to require excavation and off-site disposal of dioxin-contaminated soil.  Therefore, the final soil remedy includes 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 ROD modification, the State and EPA determined that it would not be necessary to invoke the contingent remedy for groundwater.  Beyond the property line, the monitoring wells and a private well showed no detection of contamination.

In 1997, the United States Environmental Protection Agency with assistance from the Minnesota Pollution Control Agency (MPCA) removed 38 deteriorating drums, containing spent PCP solution. This allowed MPCA to decontaminate and move and / or dismantle 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 December 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.  Subsequent monitoring is being performed by MPCA and/or its contractors.  Groundwater monitoring continues and has confirmed that the contaminant plume does not extend beyond the property boundary.    

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 short-term, but that certain actions were needed to ensure long-term protectiveness.  These actions included evaluation of an additional soil area known as Area A and evaluation of potential groundwater flow to the northeast, and evaluation of institutional controls.  These actions are ongoing at the site.   




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

Community Involvement Coordinator, U.S. EPA
dave novak
(312) 886-7478

Site Profile Information

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


Local Navigation

Jump to main content.