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Congressional District # 06


EPA ID# OHD980612147
Last Updated: May, 2015

Site Description

The Union Carbide Corporation (UCC) Site is located in Warren Township, Washington County, Ohio, and is approximately four miles southwest of the City of Marietta, on Ohio State Route 7. The UCC Plant began operations at the Site in 1950. Phenol was manufactured at the facility from 1951 to 1971 using the Raschig Phenol Process. Other products produced at the facility included polystyrene (1955-1978), liquid epoxy resin (1959-1974), bisphenol-A (1960-1974), phenolic resin and polysulfone (1965-1980), and sulfone (1968-1980). The operational facilities within the site have all been sold by UCC to other companies. Wastes that were produced by these operations were disposed onsite between 1951 and 1979. The following major areas are associated with the site:

• Raschig Area - The location of the former phenol production operations, located at the western boundary of the site;

• Site A Landfill - This area was utilized for the disposal of plant wastes, including approximately one thousand 55-gallon drums, and is located in the northern portion of the site;

• Site B Landfill - This area was utilized for the disposal of plant wastes and tar materials from 1951 until 1972. It is located east of the plant production areas adjacent to the land owned by Chevron;

• Abandoned Benzene Transfer Pipeline - A former underground transfer line utilized to transport benzene from barges on the Ohio River to the Raschig Phenol Production Area;

• North Tank Farm - In 1990, a layer of tar-like material was detected at a depth of approximately 1 to 1.5 feet below the ground surface in this area. It was located along the northern boundary of the Chevron production area;

• Unnamed Creek - The stream which flows between the North Landfill and Site A Landfill, then along the northern and eastern boundaries of Site B Landfill. Deposits of polymer and tars were visually identified in the creek and confirmed by laboratory analysis;

• Monitoring Well TW-75 Area - This area was comprised of that portion of a fly ash dike wall south of Ohio Route 7 where phenolic tars were discovered in 1991 during installation of monitoring well TW-75;

• Lime Sludge Area - Area adjacent to the Site B Landfill and includes lime ponds and a sludge drying area. This location was used as a sedimentation basin;

• The North Landfill - This area was used between 1969 and 1979 primarily for the disposal of conventional plant trash generated during routine manufacturing operations at the site; and

• Site-wide groundwater contamination - This groundwater contamination is associated with the contaminated soils at the site.

The U.S. Environmental Protection Agency (EPA) and UCC entered into an Administrative Order by Consent (AOC) in 1997. Through the AOC, UCC voluntarily agreed to implement site response actions which were selected in an Enforcement Action Memorandum. The AOC separated the site into two Operable Units (OUs): a Soil Operable Unit (OU1) and a Groundwater Management Operable Unit (OU2).

Site Responsibility

The site is being addressed through federal, state, and potentially responsible parties' actions. The site is not proposed for or listed on the National Priorities List.

Threats and Contaminants

In the Raschig Area, benzene and chlorobenzene are the predominant volatile organic contaminants (VOCs) found in the soil profile at depth, while dibenzofuran, 2,4-dichlorophenol, phenol, and total polyaromatic hyrdrocarbons (PAHs) represent some of the semi-volatile organic contaminants (SVOCs). Concentrations of the isomer 2,3,7,8-TCDD were detected in surface and subsurface soil samples.

The Site A Landfill was reported to have been prepared by excavating a saucer-like depression that was lined with heavy polyethylene liner. The major types of waste material believed to have been disposed in this landfill include styrene, polystyrene, polysulfone, dimethylsulfoxide, phenolic resins, epoxy resins, miscellaneous solvents, paints, lubricating oils, and sulfide by-products.

The Site B Landfill is an apparent source of various VOC and SVOC contaminants to the underlying sand and gravel aquifer.

The Abandoned Benzene Transfer Pipeline refers to the underground pipeline which was used to transfer benzene. The contamination found in groundwater near this area is a result of the historic failure/leaks in the pipeline.

The North Tank Farm contains chlorinated biphenyls (CBPS) and 2,3,7,8-TCDD which is indicative of the Raschig Phenol process waste.

The Unnamed Creek investigations included surface water, creek sediments, seep sediment and seep water sampling. In addition, several soil borings were sampled to determine the lateral extent of polymer and tar deposits. Chlorobenzene, styrene, and toluene are some of the VOCs detected. Dibenzofuran, phenol, and pyrene are some of the SVOCs detected. Polymer and tar deposit samples collected along the creek also showed evidence of CBPs and PCDD/PCDF contamination. Laboratory analysis of samples collected during the installation of monitoring well TW-75 revealed the presence of constituents characteristic of the tar-like material generated during the Raschig Phenol Process.

The Lime Sludge Area investigations revealed chlorobenzene and phenol in groundwater and styrene and chlorobenzene in residual lime sludge. Monochlorobenzene was detected in soils in this area.

With respect to groundwater, three plumes have been identified at the site. One plume appears to originate beneath the Site B Landfill and extends to the southwest, south and southeast of the landfill. The second plume is located beneath the vicinity of the Raschig Area and Abandoned Benzene Transfer Pipeline. The third plume is located north and northeast of the Site A Landfill and originates from the North Landfill and Site A. The main VOCs found in groundwater include chlorobenzene, toluene, and benzene. In addition, 2-butanone, ethylbenzene, styrene, trichloroethene, and phenol were also detected at elevated levels.


Cleanup Progress

EPA signed an Administrative Order on Consent with UCC in September 1984. The AOC required UCC to conduct a Remedial Investigation/Feasibility Study (RI/FS) at the site. In September 1990, EPA issued a second AOC to UCC to conduct a Supplemental Feasibility Study (SFS) at the site (excluding the North Landfill). In June 1991, EPA issued an Administrative Order to UCC to conduct an RI/FS at the North Landfill. EPA decided in March 1995 that response activities to address the North Landfill site groundwater contamination would be combined with the response activities for the remainder of the site. Subsequently, EPA decided that operation and maintenance (O&M) for the North Landfill would also be combined with the response activities for the site. Other removal activities at the North Landfill are subject to a Voluntary Action Agreement executed by EPA and Union Carbide Corporation in May 1996.

EPA signed an Enforcement Action Memorandum in May 1996 which documented the need for a Non-Time-Critical Removal Action at the site. EPA and UCC entered into an AOC which became effective in March 1997. Through the AOC, UCC voluntarily agreed to implement the site response actions. The AOC separated the site into two OUs: a Soil Operable Unit (OU1) and a Groundwater Management Operable Unit (OU2). OU1 consists of the real property that comprises the Raschig Area, Site A Landfill, Site B Landfill and Lime Sludge Area, Unnamed Creek, the North Tank Farm and, solely for purposes of O&M activities, the OU1 portion of the site also includes the North Landfill. OU2 includes the areal extent of groundwater contamination associated with OU1, the abandoned Benzene Transfer Pipeline, the Monitoring Well TW-75 Area, and the North Landfill.

The activities selected to mitigate threats associated with the site consist of the following: 1) excavation and on-site consolidation of dioxin-contaminated soils; 2) installation of RCRA Subtitle C caps for two on-site landfills; 3) installation of a bottom liner for a portion of the capped area; 4) installation of a hydraulic barrier for contaminant and gradient control; 5) installation of a 150-foot concrete culvert; 6) creek bank stabilization; 7) site-wide groundwater treatment; and 8) institutional controls.

Construction work at the site began with closure of the North Landfill. This work was completed in April 1997. Work on the Soil Containment Operable Unit (OU1) was completed in February 2002. Construction of the Groundwater Management Operable Unit (OU2) was completed in August 2003 and EPA issued its final inspection approval letter in February 2004.

As part of the startup activities of the groundwater extraction system in December 2003, samples were collected from newly installed recovery wells. Dioxins and furans were found to be present at detectable concentrations in the combined recovery well discharges for Site A and Site B. The agreement between Solvay (the neighboring wastewater treatment facility) and UCC specifically stipulates that Solvay will not accept groundwater containing dioxins. Upon receipt of the groundwater data indicating the presence of dioxins and furans, UCC immediately shut down those recovery wells and notified Solvay, EPA and Ohio EPA.

Since 2004, several investigations have been conducted at the site with the goal of arriving at a modified remedy for site groundwater. These investigations have resulted in important refinements to the conceptual site model with respect to groundwater and the Plume A Source Area. UCC has presented several remedial alternatives in a Focused Feasibility Study (FFS) for both the Groundwater Operable Unit and Plume A Source Area Operable Units. EPA and Ohio EPA have reviewed and provided comments to UCC on these studies. Upon approval, EPA and Ohio EPA will pursue amending the site’s scope of work document to delineate the appropriate modifications to address the changes to the overall remedy for the site. In the interim, in order to implement the required institutional controls for the site, UCC has been working to obtain Environmental Restrictive Covenants on properties located adjacent to the facility. Once the documents are signed by all parties, the covenants will be filed with the Washington County Courthouse.

Ohio EPA will perform the annual Operation and Maintenance Inspection at the North Landfill Operable Unit and Soil Containment Operable Unit in June 2015. 


Remedial Project Manager, U.S. EPA
linda kern (kern.linda@epa.gov)
(312) 886-7341


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