Superfund Information Systems: Site Profile

Superfund Site:

UNION CHEMICAL CO., INC.
SOUTH HOPE, ME

Cleanup Activities

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Background

The 12-acre Union Chemical Company, Inc. site is located in Hope, Maine. The Union Chemical Company began operations on site in 1967 formulating paint and coating strippers. In 1969, the company expanded its operations and began handling and recovering petrochemical-based solvents. In 1976, the company received a state permit for an underground disposal system (a septic system) for its process wastewater.

In 1979, as part of the recovery process, the company added a fluidized bed incinerator to burn contaminated sludges, still bottoms and other undetermined hazardous wastes. Some of these types of waste were burned in an on-site boiler that provided heat and operating power to the facility.

In anticipation of receiving approval for expansion of the incinerator, the company accepted additional spent solvents. Between 1979 and 1984, the plant was cited by the State of Maine for deficiencies or violations of several operating licenses. The Sate closed the waste treatment operations in 1984. The incinerator expansion was not approved and the company was unable to process all the spent solvents. At the time the State closed the waste treatment operations, about 2,000 drums and 30 liquid storage tanks containing hazardous waste were stored on the site.

The on-site soil and groundwater contamination resulted from a combination of leaking stored drums and spills and the use of the permitted septic system for disposal of the process wastewater. 

The site was placed on the National Priority List (NPL) on October 4, 1989 and removed from the NPL on September 21, 2018.

Following the removal of contaminated drums, and tanks in the mid-1980s, an investgiation was conducted to determine the nature and extent of the contamination. EPA issued a Record of Decision (ROD) in December 1990 that selected a comprehensive cleanup remedy for the facility's buildings and above-ground structures, on-site soils, off-site soils, and groundwater.

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What Has Been Done to Clean Up the Site?

As specified in the ROD, the on-site facilities were decontaminated, concrete structures crushed, asbestos in the still building containerized, and all material was shipped offsite for disposal in appropriate facilities.  The demolition debris was tested and characterized prior to off-site disposal.  The decontamination and demolition activities were completed in May 1994.

In Fall 1994, soil hot spots were consolidated into a portion of the Site and a clay soil cap was constructed over the entire area where soil cleanup would occur.  Beginning in June, and completed in December 1995, a network of 28 groundwater and 33 soil vapor extraction (SVE) wells with 91 hot air injection points was installed, a treatment building constructed, treatment equipment installed, and associated interior and exterior piping connected.

Upon completion of startup activities in October 1996, the SVE system operated continuously until March 1998.  After agency approval in March 1998, operation of the SVE system was discontinued to allow the soils to cool prior to the closure-sampling program.  The groundwater extraction system continued to operate during this period.  Closure sampling was completed in the fall of 1998.  Statistical analysis of the data by three groups working independently indicated that the soils had been cleaned up to below the ROD-specified cleanup levels.  Following acceptance of the closure sampling result, unused wells and piping were decommissioned in accordance with the Operations and Maintenance (O&M) Plan.

Following the testing of individual components with clean water in December 1995, the start-up of the groundwater extraction and treatment system was initiated on January 16, 1996. After completion of the source control cleanup in March 1998, the 28-well groundwater extraction network was reduced to three pumping wells at the downgradient edge of the SVE treatment area.  Computer modeling indicated these three pumping wells would be sufficient to control groundwater migration while groundwater cleanup activities continued.

To enhance the reduction of contaminant concentrations in the groundwater potassium permanganate was initially injected into the soils and shallow bedrock in October 1997 as a pilot study.  Based on the results of this study, potassium and sodium permanganate were used on an expanded basis in the summers of 1998, 1999, and 2000. Carbon sources in the form of molasses and sodium lactate were added in August and November 2001 to create a reducing environment to enhance degradation of ethane compounds by reductive dechlorination.  Lactate addition was carried out again in August 2002.

The extraction system has since been deactivated. The effluent discharge line from the treatment building was flushed out, then disconnected below the ground surface and grouted.  The external piping from the groundwater extraction wells was removed, and groups of extraction wells were decommissioned in 2005 and 2006.

 

In 1996, after collection of three years of meteorological data, possible areas where deposition from air emissions to off-site soils may have occurred were identified.  EPA and MEDEP, with input from the local community, selected off-site sampling locations and these were sampled in July and September 1996.  Review of the data resulted in agreement by all parties that the data did not show measurable off-site deposition in off-site soil from the Site incinerator.  In 1997, as discussed in the 1997 Explanation of Significant Differences, off-site soil activities were completed.

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What Is the Current Site Status?

The site was deleted from the National Priority List (NPL) on September 21, 2018.

The removal of contaminated drums, and tanks reduced the potential for exposure to contamination at the site.  The impact on groundwater was further reduced by the successful operation of a soil vapor extraction/hot air injection system that was operated from 1996 to 1998. With the successful cleanup of on-site soil, the soil is no longer a source of groundwater contamination. Contamination levels in the groundwater have decreased significantly through implementation of pump-and-treat technology and several innovative technologies; however, they are still above drinking water standards. It is estimated that 96 percent of the original contamination has been removed from the soils, bedrock and groundwater.

In 2011, EPA and the Maine Department of Environmental Protection (MEDEP) documented it was technically impracticable to successfully reduce remaining residual contamination to drinking water standards. EPA updated the remedy to reflect this and required use restrictions on the site to maintain the protectiveness of the remedy. These restrictions are to prohibit the use of groundwater and the installation of appropriate vapor barrier in any future buildings. Long-term groundwater monitoring is ongoing.

Cleanup Progress.

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Activity and Use Limitations

At this site, activity and use limitations that EPA calls institutional controls are in place. Institutional controls play an important role in site remedies because they reduce exposure to contamination by limiting land or resource use. They also guide human behavior. For instance, zoning restrictions prevent land uses – such as residential uses – that are not consistent with the level of cleanup.

For more background, see Institutional Controls.

Institutional Controls are required for this site.

This site requires ICs because a decision document, such as a Record of Decision, has documented some level of contamination and/or remedy component at the site that would restrict use of the site. These ICs are required to help ensure the site is used in an appropriate way and that activities at the site do not damage the cleanup components. These ICs will remain in place for as long as the contamination and/or cleanup components stay on site. The site contacts should be consulted if there are questions on the ICs for this site.
 
The following IC Instruments provide media-specific use restrictions that have been implemented by EPA for protecting human health, the environment and remedial engineering on this site. Instruments are documents used by EPA or other organizations to implement the use restrictions at a site. To know about other media-specific use restrictions that are planned but not implemented at this site, please contact the Regional Office using the Site Contact listed above.
 
Click here for IC Instruments implemented for this site.

To contact EPA regarding Institutional Controls and/or activity and use limitations, please complete this form.

 

The 1990 ROD and 2013 ROD Amendment require the implementation of institutional controls for the Site Property and nearby properties to protect human health and the environment.   On August 2, 2017, MEDEP recorded a Declaration of Environmental Covenant in the chain of title for the two lots comprising the Site Property at the Knox County Registry of Deeds (Volume 5192, Page 306).  Among other things, the Declaration of Environmental Covenant: (1) prohibits the extraction of groundwater; (2) prohibits the destruction, obstruction, tampering, or disruption of wells; (3) prohibits the discharge or injection of liquids to the subsurface; (4) prohibits the accumulation, storage, or stockpiling of wastes, and operation of a junkyard or automotive scrapyard; (5) requires a sub-slab vapor barrier and ventilation system or a sub-slab depressurization system for any constructed buildings, and (6) provides for EPA and MEDEP access to the Site Property. 

The 2013 ROD Amendment also calls for environmental deed restrictions or other mechanisms to limit the use of properties adjacent to the Site, as deemed necessary by EPA based on new information including but not limited to the development (or installation of drinking water wells) on properties adjacent to the Site or movement of the leading edge of either plume.  To date, EPA has not determined that it is necessary to implement other land use restrictions on the properties adjacent to the Site.

ICs are generally defined as administrative and legal tools that do not involve construction or physically changing the site. Common examples of ICs include site use and excavation restrictions put in place through State and local authorities like zoning, permits and easements. ICs are normally used when waste is left onsite and when there is a limit to the activities that can safely take place at the site (i.e., the site cannot support unlimited use and unrestricted exposure) and/or when cleanup components of the remedy remains onsite (e.g., landfill caps, pumping equipment or pipelines). Effective ICs help ensure that these sites can be returned to safe and beneficial use.
 
Disclaimer: This information is being provided by EPA as an informational tool to further assist the public in determining the types of restrictions that may be in place at National Priorities List sites being addressed by EPA under the Superfund program. In addition to the areas addressed by the institutional controls identified on this web site there may be other areas on the property that require restrictions on use of the property that are not captured in this EPA database. States and other entities may have implemented laws or restrictions applicable to this site. The information provided herein does not replace a title search or meet "All Appropriate Inquiry" requirements. U.S. EPA encourages users to review the Site files to obtain information regarding remedy components, containment systems and the land use for which cleanup standards were selected for these sites. More information and links can be found in the Institutional Control instrument collection of document, above, and the EPA regional offices may also be contacted.

 

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Sampling and Monitoring

A surface water and groundwater monitoring program has been performed since Summer 1992 to monitor the contaminants at the Site, assess the progress of the remedial action and evaluate potential impacts to Quiggle Brook and groundwater during the remedial activities.  The program was performed initially on a quarterly basis from Summer 1992 through Fall 1997 (22 sampling events), then semi-annually through Fall 2004 (14 sampling events).  The monitoring plan was modified in 2005 while pumping tests of the bedrock groundwater were being conducted and then resumed in Fall 2006.  Beginning in 2008, monitoring was reduced to every two years.  Groundwater and surface water samples have been analyzed for 24 site-specific contaminants.

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Enforcement Information

EPA and Maine Department of Environmental Protection (MEDEP) entered into a Consent Decree with the parties responsible to perform the remediation activities.

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