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CIPS Taylorville
Taylorville, Illinois
Christian County
The former Ameren Central Illinois Public Service Superfund Site is located at 917 South Webster Street in Taylorville, Illinois. The Site is approximately 1.2 acres in size and along with two adjacent parcels also owned by Ameren make up an area of approximately 20.8 acres.
The three parcels are subject to an Environmental Covenant (EC) with the Illinois EPA, restricting disturbance of soil and use of groundwater for potable purposes within the EC Area. The Site lies in a residential area adjacent to Manners Park. The site was designated as a "State-lead" enforcement case with Illinois EPA as the lead agency and United States Environmental Protection Agency (USEPA) Region 5 as support agency.
Background
The former manufactured gas plant (MGP) was constructed in 1892 and was operated by the Taylorville Gas and Electric Company until it was purchased in 1912 by Ameren predecessor companies. Ameren predecessors operated the MGP from 1912 until 1932. The plant produced a low-quality gas from coal, which was used for lighting and heating. When the plant was closed, most of the above ground structures were torn down. Below ground tanks reportedly were filled with soil and miscellaneous materials and left in place.
Various response actions were completed at the site, such as demolition and removal of all former MGP structures above and below ground, excavation, and offsite disposal of approximately 12,000 cubic yards of contaminated soil and sediments in the drainage swale; and backfilling of affected areas with clean soils. Groundwater at the Site was contaminated with polynuclear aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). A pump and treat (P&T) system to address contaminated groundwater has been active on the site since 1995. In an effort to accelerate remediation, In-Situ Chemical Oxidation (ISCO) was applied to source materials in 2006-2007 and 2010-2012.
Current Actions and Remediation
A portion of the parcel is utilized for the P&T facility and storage of remediation support materials. The P&T system uses two extraction wells to remove groundwater from the site for on-site treatment. The treated water is discharged to the drainage system that flows to Seaman Estates Pond.
The existing P&T system, while effectively removing most of the groundwater contamination, would take an estimated 100 years or longer to meet the Illinois Groundwater Quality Standards. For this reason, the Illinois EPA proposed in situ solidification and stabilization (ISS) as an additional remedial action. For ISS, a slurry mixture of binding agents is developed and mixed with subsurface soil using large diameter augers. The mixture then cures and hardens in place creating a solid stable structure below the surface. Stabilization can also include mixing contaminated soil with other binding agents, which are intended to cause a chemical reaction with COCs to make them less likely to be released to the surrounding environment.
A Remedial Design Investigation was conducted in May-November 2022 to determine if ISS is a feasible remedial alternative for the Site. During the investigation over 2,000 groundwater and soil samples were taken. Ameren submitted a Focused Feasibility Study to Illinois EPA in the spring of 2023. The study examined potential remedial options. From August 11,2023 to October 4, 2023, Ameren conducted an ISS Pilot Study to determine the effectiveness of different ISS mixes.
After receiving odor complaints from community members and conducting a site inspection, Illinois EPA issued Ameren a stop work order on the Pilot Study on October 4th, 2023.
To ensure the project was protective of human health and the environment, Illinois EPA reviewed Ameren’s Revised Ambient Air Monitoring Plan and the Summary of Air Emissions Monitored During Pilot Study and Corrective Measures Taken Report. After review, on December 21, 2023, Illinois EPA sent Ameren a letter outlining the “The Next Steps Forward for the Ameren CIPS Taylorville Site”. The letter addressed ongoing comments and clarified the State’s requirements before the ISS Pilot Study could continue.
In January 2024, Ameren notified Illinois EPA that the ISS Pilot Study will be suspended, and the site would be demobilized and the disturbed area restored. Restoration work included backfilling, grading, installing liners, utility restoration, soil and water management, surveying, monitoring well abandonment, groundwater sampling, air monitoring, and site security. Site restoration was finished in March 2024.
The P&T system is still operating.
Additional Site Information
Groundwater
Groundwater monitoring wells are located on the site, at the site boundary and off-site. There are 30 years of data to show the plume is contained onsite and does not migrate towards residences. Groundwater samples are collected quarterly.
Soil
Most of the contaminated soil located above the groundwater table was removed in 1987. In 2022, a soil investigation was conducted in the Remedial Design Investigation and 87 soil borings were taken. Samples were collected every 2 feet- 50 feet below ground surface and every five feet below that until bedrock. A total of 2,821 samples were taken.
Air
During the Pilot Study and demobilization process, Ameren followed their Ambient Air Monitoring Plan. Ameren collected air data around the site for contaminates of concern hourly while employees were on site. During the pilot study, there were five stationary air monitoring stations that collected information around the site 24/7 and results were compiled weekly. The Plan outlined action levels for contaminants of concern and the response action to be taken if actions levels were reached. Without construction onsite, air monitoring is not currently taking place.
What to Expect?
Ameren continues operating the P&T system. Prior to making any major changes to the Record of Decision, a public notification and public comment period would be held. If you would like to be added to the mailing list for this site, please contact the Illinois EPA contact listed below.
Documents
Illinois EPA encourages the public to review documents that make up the Administrative Record to gain a more comprehensive understanding of the Site and remediation activities that have been conducted. The Administrative Record for the Site can be accessed at the following location:
Taylorville Public Library
121 West Vine Street
Taylorville, IL 62568
Phone: (217) 824-4736
Illinois EPA maintains an Information Repository for the Site, which includes the full Site record. The Information Repository is available online at:
https://webapps.illinois.gov/EPA/DocumentExplorer/Documents/Index/170000173096
Additional Documents
Public Meeting Presentation (3/26/2024)
Public Meeting Flyer (3/26/2024)
Superfund Process Flyer for Ameren Taylorville site
For more information on the multiple alternatives considered, see the Focused Feasibility Study.
Contacts
Sarah Brubaker, Office of Community Relations
sarah.brubaker@illinois.gov
217-786-0790
For more information, please contact the Illinois EPA Office of Community Relations. Additional documents not available on this webpage may be obtained through a Freedom of Information Act request or through IEPA Document Explorer.