The Site is a former wood treating facility which treated wood with pentachlorophenol (“PCP”) on a 13.5 acre parcel from 1959 to approximately 1982. Sludge from the pressure treating process was deposited in lagoons on the northern edge of the Site. EPA has information that these lagoons caught fire sometime in the early 1970s, and that sludge from the wood treating operation was burned in an on-site boiler used to steam the wood before treatment. Water from the lagoons went through an on-Site treatment system, then into the city sewers. A ground water diversion, interception and collection system designed to capture water carrying leachate from the Site was constructed in the late 1970s. Water from this system was pumped to a treatment facility prior to being discharged into the city sewers. The lagoons were closed in 1978-1979 and were backfilled with soil. In 1975, Sentinel began manufacturing hog houses and later, in 1980, outdoor wood furniture made with lumber treated with copper chromated arsenic (“CCA”). Although the CCA lumber was treated off-Site, the sawdust and scrap wood from the manufacturing was burned on Site. Sentinel ceased operations in the late 1980s.
EPA entered into an AOC in 2001 with the PRP who agreed to conduct a removal action. An enforcement action memorandum was signed in August 2001. The scope of this removal action included:
- Establish and maintain security measures to control access to the Lagoon Area of the Site to prevent unknowing, unauthorized entry and exposure to contamination.
- Prevent off-site migration of contamination via surface water.
- Operate and maintain the ground water diversion system.
In December 2004, EPA signed a second action memorandum requiring the PRP to conduct additional actions including the following:
- excavate highly contaminated source soils and transport off-site for disposal.
- Construct a biotreatment cell for the treatment of low to moderately contaminated source soils.
- Apply chemical oxidation treatment to highly contaminated areas of ground water in order to better control off-site migration of contaminated ground water.
EPA and MDNR conducted additional assessment activities at the site in 2010. In 2011, EPA concluded that the activities required by the first action memorandum have either been completed or have been taken over by the second removal action. Therefore, this POLREP documents completion of the first removal action. The second removal action is still ongoing and will likely continue for several more years.
Planned removal actions at the site include continued biotreatment of site soils and chemical injection to treat highly contaminated groundwater. These activities are being conducted under the second removal action.
Next steps include continued oversight of the PRP lead actions at the site to treat onsite soils and ground water. It is anticipated that the second removal action will continue for several more years.
Evaluation of the monitoring well network revealed that operation of the drainage diversion system did not reduce the concentration of PCP getting into the stream flowing off-site. This discovery resulted in a second removal action to more aggressively treat source soils and ground water.
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