Occidental Chemical Corporation, Inc. Facility, Wichita, Sedgwick County, Kansas - Fact Sheet, June 2018

Public Comment Period for Proposed Remedy

INTRODUCTION

The U.S. Environmental Protection Agency (EPA) Region 7 invites the public to comment on the Proposed Remedy for the Occidental Chemical Corporation, Inc. (Occidental) facility site near Wichita, Kansas.

The Proposed Remedy includes measures to control the migration of an existing groundwater contaminant plume and reduce its size; excavate and consolidate contaminated surface soil and then consolidate it into the existing on-site landfill; install a seep collection system to enhance the landfill cap; install 10 recovery wells to extract dense non-aqueous phase liquid (DNAPL) contamination beneath the site; establish measures to protect against vapor intrusion concerns for several on-site buildings; as well as maintain existing asphalt and concrete cover and institute activity and use limitations to restrict use of impacted groundwater and future use of the property.

The public comment period runs from June 26, 2018, through August 9, 2018. EPA will hold a Public Availability Session on June 26, 2018 (see details below).

Written comments on the Proposed Remedy must be mailed or emailed no later than August 9, 2018, and must be sent to:

Brad Roberts
EPA Region 7 (AWMD/WRAP)
11201 Renner Boulevard
Lenexa, KS 66219
Email: roberts.bradley@epa.gov

BACKGROUND

The site is an active chemical manufacturing plant, located at 6200 South Ridge Road on approximately 160 acres of land in Sedgwick County, Kansas, approximately 5 miles southwest of the city of Wichita.

Frontier and Tennessee-Frontier began production of chlorine, sodium hydroxide, hydrochloric acid, and benzene hexachloride (BHC) at the site in 1952.

The Vulcan Materials Company (Vulcan) became the owner in 1957. At the time of purchase, the site was producing chlorine, caustic soda, hydrochloric acid, Lindane; 2,4-dichlorophenoxyacetic acid (2,4-D); pentachlorophenol, and various chloromethanes (methylene chloride, chloroform, and carbon tetrachloride).

In 1958, Vulcan began producing perchloroethylene. In 1959, Vulcan ceased 2,4-D production and began producing anhydrous hydrochloric acid.

In June 2005, Occidental Chemical Corporation purchased the site from Vulcan. Pentachlorophenol production ceased in June 2005.

Beginning in 1955, several on-site production wells were closed due to hardness and chloride contamination. In 1960, a study of salt contamination was performed at the Westar Energy, Inc. Murray Gill Energy Center, located to the northeast of the site. This began a series of groundwater investigations performed at and near the site.

Following passage of the Hazardous and Solid Waste Amendments in 1984, EPA conducted a Resource Conservation and Recovery Act (RCRA) Facility Assessment (RFA) at the site in 1986 and 1987. In May 1987, an RFA report determined that releases, potentially including off-site releases of hazardous materials, had occurred at the site.

EPA issued to Occidental a RCRA Permit to address corrective action requirements on August 30, 2007. A number of investigative steps and permitting actions were performed, and interim corrective measures were put in place to protect human exposures over the years prior to conducting a full investigation of contamination under the operating plant. In 2008, a RCRA Facility Investigation (RFI) Schedule of Work was agreed upon between EPA and Occidental. For the investigations that involved the collection of field samples, work plans outlining the scope of work for each area of concern were developed and submitted to EPA for review and approval.

The RFI data facilitated the development of a conceptual site model that characterized the nature and extent of contaminants in soil and groundwater, evaluated potential exposure pathways, and identified potential receptors. The conceptual site model identified potential release areas in parts of the process area and the landfill area.

SOIL: The following chemicals were detected in the soil at concentrations greater than the screening criteria, and therefore were identified as chemicals of potential concern (COPCs): pentachlorophenol, alpha-BHC, beta-BHC, hexachlorobenzene, hexachlorobutadiene, hexachloroethane, carbon tetrachloride, chloroform, perchloroethylene, trichloroethene; 2,4,6-trichlorophenol; 2,4-dichlorophenol; 1,2-dichloroethane; and 1,2-dichloropropane. In addition, 2,6-dichlorophenol and 3/4-chlorophenol were identified as COPCs because they were detected with no screening criteria for these parameters.

GROUNDWATER: The following chemicals were detected in the groundwater at concentrations greater than the screening criteria and therefore were identified as COPCs: 2,4-dichlorophenoxyacetic acid (2,4-D); pentachlorophenol; 2,3,4,6-tetrachlorophenol; 2,4,6-trichlorophenol; 2,4-dichlorophenol; 2-chlorophenol; alpha-BHC; beta-BHC; delta-BHC; gamma-BHC; hexachlorobenzene; hexachlorobutadiene; hexachloroethane; 1,1,1-trichloroethane; 1,2-dichloroethane; 1,2-dichloropropane; benzene; carbon tetrachloride; chloroform; methylene chloride; perchloroethylene; trichloroethene; and vinyl chloride. In addition, 2,3,4,5-tetrachlorophenol; 2,6-dichlorophenol; and 3/4-chlorophenol were identified as COPCs, as they were detected with no screening criteria for these parameters.

SOIL VAPOR: By means of an assessment for potential soil vapor intrusion concerns, 236 structures at the site were screened based on whether each structure is routinely occupied, construction type, and whether there is already a vapor intrusion mitigation system in place. Following the screening, soil vapor sampling was performed adjacent to each structure. The resulting data suggests that, in addition to some structures that already have measures in place to protect from vapor intrusion concerns, two additional structures within the process area have contaminants, including carbon tetrachloride, chloroform, hexachloroethane, and tetrachloroethene, at concentrations in soil vapor adjacent to the structures exceeding screening criteria.

CONTAMINANT RISKS

Following completion of individual RCRA Facility Investigation (RFI) reports for several areas, a comprehensive RFI report, and Supplemental RFI report, screening was performed for each environmental media to begin the risk assessment. An evaluation of potential receptors, routes of exposure, and site-specific factors impacting exposure was performed to determine if, or to what degree, the levels of contamination necessitate corrective measures. The Human Health Risk Assessment resulted in risk estimates for contaminated surface soil and groundwater that were above EPA’s acceptable limit of a 1-in-10,000 chance of cancer, and also above acceptable limits for non-cancer health effects.

CLEANUP GOALS

Site specific cleanup goals were calculated for two carcinogenic chemicals at a target cancer risk limit of 1 in 10,000 that is also protective of non-cancer health effects. The two calculated surface soil cleanup goals are pentachlorophenol at 441 mg/kg (milligrams per kilogram) and alpha-BHC at 458 mg/kg. 

The risk estimate for exposure to groundwater off-site in the potential future residential use scenario was also unacceptable. Rather than calculate site-specific groundwater cleanup goals, EPA proposes for both on-site and off-site to use Maximum Contaminant Levels (MCLs) established under the Safe Drinking Water Act, 42 U.S.C. sections 300f - 300j-26. The MCLs represent the maximum permissible levels of a contaminant in water that is delivered to any user of a public water system. If no MCL is available, EPA proposes that the corresponding tap water Regional Screening Levels (RSL) will be used.

PROPOSED FINAL REMEDY

The Proposed Remedy entails:

• Continued operation of the existing groundwater interceptor well system with groundwater plume monitoring, and the addition of one extraction well, including a specific performance goal and additional measures that may be considered for reducing the plume extent to the plant boundary within 25 years
• Concrete and asphalt ground cover with inspection and maintenance for surface soil in the process area, which includes the closed asbestos surface impoundment
• Excavation of 3,000 cubic yards of surface soil with consolidation into the existing landfill
• Existing landfill inspection and maintenance, plus installation of a seep collection system to enhance the landfill cap
• Maintain existing building pressurization heating, ventilation, and air conditioning (HVAC) system, with inspection and reporting to protect against vapor intrusion for a limited number of buildings
• Inspection with maintenance or additional measures, as needed, based on inspection findings to protect against vapor intrusion for two additional buildings
• Installation and operation of 10 vertical recovery wells for dense non-aqueous phase liquid (DNAPL) removal, with annual performance evaluations
• Activity and use limitations under an institutional control to prevent human contact usage of impacted groundwater; limit future site use to commercial or industrial; and require a Media Management Plan and a Health and Safety Plan to prevent exposures during future excavations on-site

FOR MORE INFORMATION

Comments or requests for information must be submitted prior to the expiration of the public comment period, which ends August 9, 2018.

• Explain your views.
• Tell us if you support or disagree with the Proposed Remedy. Please be specific.
• Provide potential alternatives to the Proposed Remedy, if you choose to.

The Administrative Record is available during normal business hours at the following locations hours:

Haysville Community Library
210 South Hays
Haysville, KS 67060
316-524-5242

EPA Region 7 Records Center
11201 Renner Boulevard
Lenexa, KS 66219
1-800-223-0425

A Public Availability Session will be held:
 
Tuesday, June 26, 2018
6:00 to 8:00 p.m.
Campus High School
2100 55th Street South
Wichita, KS 67217

A formal public hearing is not planned, but can be scheduled if requested. Any request for a public hearing must be made in writing to the EPA contact at the address listed on Page 1, and must state the nature of issues to be raised. EPA will evaluate any requests and hold a public hearing if it finds that doing so will contribute to the decision-making process by clarifying significant issues affecting the Proposed Remedy.

EPA will make a final decision on the Proposed Remedy only after the public comment period ends and all comments are reviewed. EPA may modify the Proposed Remedy based on any new information and comments from the public.

Individuals may write to the EPA contacts below to join the mailing list. Joining the mailing list will allow an individual to receive any updated information directly throughout the remedy selection process.

If you have questions or want to receive further information, please contact:

Tamara Freeman
Enforcement Coordination Office
U.S. EPA Region 7
11201 Renner Boulevard
Lenexa, KS 66219
Toll-free: 1-800-223-0425
Email: freeman.tamara@epa.gov

OR

Brad Roberts
EPA Region 7 (AWMD/WRAP)
11201 Renner Boulevard
Lenexa, KS 66219
Email: roberts.bradley@epa.gov