EPA to Propose Remedy Modification, Chemplex Superfund Site, Clinton, Clinton County, Iowa
The U.S. Environmental Protection Agency (EPA) is in the process of evaluating whether it is appropriate to revise the remedy for the Chemplex Superfund site.
FOCUSED FEASIBILITY STUDY
The present ground water cleanup remedy is not working as well as expected. Although the present remedy has partially addressed ground water contamination it has also caused the contamination to move in the aquifer to areas that were previously uncontaminated.
EPA requested that Citigroup and ChevronTexaco (known as "ACC/GCC"), the parties conducting the Chemplex Site cleanup, prepare a Focused Feasibility Study (FFS) to evaluate other remedies. The FFS was finalized in July 2007 after receipt of comments from EPA and the public on the draft FFS. The revised remedy recommended in the final FFS was the “exposure control” alternative, which includes the following components:
- enhanced ground water monitoring;
- hot spot treatment of the most highly contaminated ground water;
- contingency measures to protect human health and the environment;
- land use controls to prohibit use of the ground water in the contaminant plume;
- extension of the City of Camanche municipal water line to residents located downgradient of the site; and
- establishment of a technical impracticability (TI) waiver to define where appropriate ground water cleanup levels will be met.
EPA requested that ACC/GCC conduct a performance test of the exposure control alternative identified in the FFS.
The original ground water remediation method was a “pump and treat” system to capture and contain contaminated ground water. It operated from late 1994 until September 2008. In September 2008 it was placed in temporary standby condition as part of the performance test. The performance test allowed the ground water system to return to natural flow conditions, which the parties believed would both facilitate hot spot treatment and better enable natural attenuation processes to clean up the contaminated ground water.
Other components of the performance test that were conducted include:
- Additional ground water monitoring wells were installed. It appears that the ground water contaminant plume has not moved significantly from 2008 to 2010.
- The hot spot pilot study has been completed and shows promising results in reducing contamination.
- A contingency plan that discusses measures which will be implemented if the ground water plume migrates unexpectedly.
- Land use controls have been implemented.
- The City of Camanche water supply system has been extended to areas that may be affected by the ground water contamination and many residents have been hooked up to City water.
ACC/GCC continues to monitor the contaminant plume by collecting and analyzing ground water data. EPA continues to review all monitoring reports and collects and analyzes independent ground water samples to ensure human health and the environment are protected.
If EPA were to change the remedy, the next step in the process would be for EPA to make available a Proposed Plan for public review and comment. The proposed plan will include a description of the proposed remedy changes and an explanation of the basis for those changes. After considering public comments, EPA would then issue an amended Record of Decision (ROD Amendment) revising the remedy.
The Chemplex facility in Clinton County, Iowa, was constructed in 1967 and has been in operation since then. Equistar Chemicals, LP, is the current owner/operator. The facility manufactures high and low-density polyethylene plastics from chemical stock.
Due to past waste disposal practices, ground water and soil at the site were contaminated with volatile organic compounds (VOCs) and polynuclear aromatic hydrocarbons (PAHs). EPA divided cleanup activities at the Site into two phases, called operable units. Operable unit (OU) 1 addressed ground water on a site-wide basis and OU2 addressed contaminated soils and wastes which were sources of ground water contamination.
Detailed site information, including the 2007 FFS, is available at the following locations:
EPA Records Center
901 N. 5th St.
Kansas City, Kan.
Camanche Public Library
102 12th Ave.
Questions or requests for information can be submitted to:
Community Involvement Coordinator
U.S. EPA Region 7
901 N. Fifth St.
Kansas City, KS 66101
Toll free: (800) 223-0425