The 12-acre Union Chemical Company, Inc. site began operations in 1967 as a formulator of paint and coating strippers. In 1969, the company expanded its operations and began handling and recovering petrochemical-based solvents. 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. Between 1979 and 1984, the plant was cited by the State for deficiencies or violations of several operating licenses. The State closed the waste treatment operations in 1984, at which time approximately 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 improper handling and operating practices such as leaking stored drums, spills, use of a septic tank and a leachfield for disposal of process wastewater, and could also be attributed to past disposal methods. There are approximately 200 people living within a 1/2-mile radius of the site. These residents depend on groundwater for domestic use. The site is bounded by Quiggle Brook and is partially in the 100-year flood plain. Grassy Pond is less than 1 mile east of the site and is an alternate drinking water source serving approximately 22,800 people in the Towns of Camden, Rockport, Rockland, and Thomaston.
Threats and Contaminants
The Remedial Investigation found that the buildings and other plant facilities contained heavy metals, dioxins, and asbestos. Approximately 2 1/2 acres of the site are fenced and contained the former processing buildings, two aboveground storage tanks, a former drum storage area, and incinerator facilities. On-site groundwater and soils are contaminated with volatile organic compounds (VOCs) including xylenes, trichloroethylene, tetrachlorethylene, and 1,1-dichlorethene. Off-site surface water contamination may have occurred through discharges of contaminated process wastewater into the adjacent Quiggle Brook and through natural discharge of contaminated groundwater into the brook. People who come into direct contact with or accidentally ingest contaminated groundwater could be at risk.
The site is being addressed in two stages: immediate action and long-term remedial action. The long-term remedial action has four components: demolition and removal of the buildings and structures on site; clean up of the on-site soils to performance standards established in the 1990 Record of Decision (ROD); evaluation of off-site soils for possible impact from the facility's incinerator; and restoration of the groundwater beneath the site.
Response Action Status
Immediate Actions In 1984, the State and EPA collectively
removed all surface drums, over 100,000 gallons of liquid wastes and sludges
from aboveground storage tanks, and some contaminated soil from the site.
Facilities Based on results of site investigations, EPA selected the following remedies in 1990:soil excavation and on-site low-temperature soil aeration treatment; vacuum-enhanced groundwater extraction, on-site groundwater treatment, and on-site discharge of treated groundwater into Quiggle Brook; facilities decontamination and demolition, and off-site disposal of debris; and further monitoring and analysis of off-site soils to determine whether contamination is present as a result of past site operations. Throughout all phases of the data collection and analysis effort, EPA will determine if additional cleanup actions are required. The design for these remedies began in late 1991 and was completed in 1995. From 1993 to 1994, the facilities decontamination and demolition was completed.
On-Site Soils In 1994, EPA with the Maine Department of Environmental Protection and community concurrence, adjusted the treatment to soil vapor extraction of the contaminated soils. In addition, the groundwater extraction system was significantly expanded to clean up groundwater more quickly at the site. In late 1994 and early 1995, EPA began limited source control actions in preparation for the soil vapor extraction and groundwater extraction systems. The soil vapor extraction and groundwater extraction systems began operating in early 1996. Compliance sampling of the site soils in September 1998 demonstrated that the soil performance standards had been achieved.
Off-Site Soils Meteorological data was collected on-site to address concerns that airborne material from the incinerator had impacted residential property. Sampling locations were selected based on modeling of the data and input from the community. The results showed no impact from the site incinerator. Further description of response to off-site soils can be found in EPA's September 1997 Explanation of Significant Differences ( ESD).
Groundwater Start-up of the groundwater extraction system began in February 1996. The groundwater cleanup efforts were augmented with the addition of potassium and sodium permanganate into the subsurface in 1998, 1999, and 2000; molasses and sodium lactate solutions (as carbon sources) in 2001 and 2002; and hydrogen peroxide in 2005. With the groundwater extraction system following the expected course of decreased removal of contaminants, the system was deactivated at the end of 2000 Based on the available data, EPA believes that the contaminant plumes in both the shallow soils and bedrock attentuate to drinking water quality prior to the property boundaries.
2007 Five-Year Review EPA has just completed a five-year review of the Site as required under the Superfund law. EPA concluded that the remedy remains protective of human health and the environment in the short-term, but that institutional controls on the property will be needed to assure long-term protectiveness,
Enforcement Highlights In 1987 and 1988, EPA, the State, and 288 parties potentially responsible for contamination at the site entered into two Administrative Orders. In these Orders, the parties agreed to conduct an investigation to examine the possible cleanup alternatives and reimburse EPA and the State for approximately 80 percent of past cleanup costs. In 1989, EPA entered into a Consent Decree with nine additional potentially responsible parties where the parties agreed to reimburse EPA for additional incurred past costs and certain litigation costs. In 1991, EPA entered into a Consent Decree with the past owner/operator for reimbursement of additional EPA past costs and for a Resource Conservation and Recovery Act (RCRA) Administrative Order violation from 1987. Also in 1991, EPA filed three separate Consent Decrees with three potentially responsible parties for violations. A Consent Decree between EPA, the State, and 60 potentially responsible parties was issued in 1991 formalizing an agreement for the parties to support site cleanup. In early 1992, EPA, Maine DEP, and 270 potentially responsible parties formalized a settlement agreement.
The removal of contaminated drums, tanks, and soil has reduced the potential for exposure to contamination at the Union Chemical Company, Inc. site. With the successful cleanup of the on-site soil, the soil is no longer a source of contamination to the groundwater. Contamination levels in the groundwater have been decreased significantly since the Remedial Investigation through implementation of pump-and-treat technology and several innovative technologies but are still above drinking water standards.
Current Site Status
EPA, MEDEP, and the PRPs are updating the Conceptual Site Model - a synthesis of all geologic, hydrologic, and chemistry data used to develop a comprehensive explanantion of the fate and transport of the site contaminants. This document will form the basis for determining the next steps for the Site.
See the internet EPA report for more information.