Groundwater Contamination at the Former WearEver Aluminum Facility in Chillicothe, Ohio: Plume Containment, Expanded Monitoring, and Better Modeling Planned

     The WearEver Aluminum Company was established in Chillicothe, Ohio, in 1948. A 1986 EPA groundwater pollution report detailed a contaminant plume spreading toward the Scioto River and residential areas near Chillicothe’s wastewater treatment plant. The plant remained open until the late 1990s. Contaminants released during plant operations include trichloroethylene (TCE), benzene, vinyl chloride, lead, and cadmium. Consistently high TCE levels remain a major concern. Workers at the plant were exposed to hazardous pollutants, and cases of rare cancers, respiratory illnesses, and neurological disorders have been potentially linked to exposure, including prolonged exposure to toxic fumes during degreasing operations and lead-contaminated walnut shell dust used in polishing processes.

     Howmet Aerospace is the current owner of the property and is leading the cleanup efforts. The success of the cleanup has been called into question by water sampling and analysis that reveal persistently high contaminant levels. TCE levels have remained high and have reached levels as high as 400 micrograms per liter (µg/L)—80 times the EPA’s Maximum Contaminant Level (MCL) of 5 µg/L. Vinyl chloride levels were up to 100 times the EPA MCL in one well.

     Jay Salley, in a January 2025 article in the Scioto Valley Guardian, summarized the Ohio EPA’s critique of Howmet’s cleanup project and its conditions for remediation of the site, which include getting a better handle on the size and migration of the contaminant plume:

     Howmet is complying with EPA orders by drilling more monitoring wells, changing its plume modeling methods, and enhancing data collection, which I assume means, in part, getting more samples for analysis.

     Ohio State University professor Linda Weavers, co-director of the Ohio Water Resources Center, noted that the plume is very localized, about 28 feet underground at the southeast side of the city, east of the Pixelle plant and west of U.S. 23 and the Scioto River. The Pixelle plant is a paper mill that is scheduled to close at the end of the year unless it finds a buyer. The plant’s operations use about 1 billion gallons of water per year, which keeps the water levels low in the shallow aquifer in which the contaminant plume is confined. Thus, it is thought that the high water usage at the plant is helping to contain the plume, and turning that water off risks a “worst case scenario” where the plume migrates out and toward the surface as the water table rises. It is expected that the Ohio EPA, Howmet, and Pixelle, or its future owner, will come to an agreement of some sort to keep the plume contained. In any case, there is a clear need for expanded monitoring and data collection. The plume moves very slowly, and the remediation strategy for the site is to monitor and contain the plume so that chemicals don’t migrate and hurt the environment or nearby communities. In time, underground microorganisms in the aquifer will break down the chemicals, but that is a very slow process. Weaver notes that there are many such contaminated groundwater sites around the country where slow natural bioremediation and contaminant plume monitoring and containment are the remediation methods.

     Key Environmental, Inc. is preparing quarterly groundwater monitoring reports for the Ohio EPA. They note in the introduction to their Second Quarter 2025 report that:

“Historical manufacturing at the Howmet Aerospace Inc. (formerly known as Alcoa Inc. and more recently known as Arconic Inc.) Former WearEver Facility (Site) located in Chillicothe, Ohio has resulted in the presence of volatile organic compounds (VOCs) in subsurface soils and groundwater at the Site.”

     The contamination plume extends east-northeast to the paper mill’s non-potable wells about 2000 ft away. Below, the report gives the historical remediation strategy and implementation:

“The 1998 Decision Document identifies the selected remedy for groundwater based on the Remedial Action Objectives (RAOs) which were:

·        "Control access to affected groundwater, both on-site and off-site, such that unacceptable exposure does not occur, and

·        Ultimately achieve Maximum Contaminant levels (MCLs) for select volatile organic compounds (VOCs) found in the groundwater on-site. "

“To achieve the RAOs, the remedy selected by Ohio EPA for groundwater was a combination of the Source Area soil vapor extraction / air sparging (SVE/AS) and the Limited Action alternatives. The Limited Action alternative includes groundwater monitoring to evaluate the effectiveness of the SVE/AS at the source areas and to monitor both the on-site and off-site plume.”

“In March of 1999, Alcoa entered into an agreement (Director's Final Findings and Orders) with the Ohio Environmental Protection Agency (Ohio EPA) to perform the remedial actions at the Site, and to monitor the groundwater plume. Although the on-Site remedial actions have improved groundwater quality, the off-Site VOC groundwater plume is expected to persist for many years.”

“Ohio EPA included contingencies in the selected alternative to address a future situation like the anticipated cessation of pumping of the Pixelle production wells which is a groundwater use modification. Specifically, the 1998 Decision Document states: "under this alternative, contingencies are provided in the event that operation of any of the industrial wells along the Scioto River changes in such a way that the plume of VOC impacted groundwater changes in size or direction." Howmet is currently collaborating with Ohio EPA to implement the contingencies listed in the 1998 Decision Document which include:

·        "Evaluate the proposed groundwater use/change and determine the potential human health and environmental risks (including the risk of contaminating previously uncontaminated groundwater);

·        Identify alternative responses to the proposed groundwater use/change if determined to pose an unacceptable risk; and

·        Work with the [potentially downgradient] landowner and Ohio EPA to implement the alternative response that best suits the [potentially downgradient] landowner's needs, minimizes risk, and is most cost-effective.

     The Groundwater monitoring plan was updated in 2012 to include monitoring groundwater flow direction and increased water quality monitoring along the plume. Current objectives by Key Environmental are given below.

The objectives of the quarterly monitoring events described in the revised GWMP are as follows:

1) Confirm that hydrodynamic control of the existing off-Site VOC groundwater plume is maintained by the Pixelle Collector Wells 17 and 18, located to the east and northeast of the Site, by detecting potential southerly shifting of the plume toward potential groundwater receptors southeast of the Site; and

2) Monitor the sample concentrations of the off-Site plume.

In addition to these objectives, the GWMP includes performing water level measurements in selected wells to monitor the groundwater flow direction and the Groundwater Use Notification Agreements (GWUNAs) placed on the properties surrounding the Site.

     In addition to this, they are modeling what would happen if and when the paper mill water withdrawals are discontinued. The plan is to begin an enhanced monitoring program beginning August 1, 2025, to characterize and evaluate the steady-state conditions during the anticipated cessation of pumping from the paper mill wells. After the groundwater conditions are thoroughly characterized, an appropriate response action can be determined.” 

     Below are maps showing the mapped contaminant plume, some monitoring wells, and monitoring well locations.

     Howmet uses Field and Technical Services (FTS) to conduct groundwater monitoring. They installed passive diffusion samplers in the quarterly monitoring wells, and water levels are recorded regularly in the 18 monitoring wells and the 7 Pixelle wells. A piezometric surface map is shown below, which measures the groundwater elevation, or water table in the aquifer. The groundwater gradient is clearly decreasing to the east and east-northeast.  

     A zoomed-out piezometric surface map with the Pixelle wells shown gives the gradient alteration presumably from two of the wells’ cones of depression, along with the east-northeast groundwater flow direction.

     The historical and current contaminant levels for the VOCs TCE, cis-1,2 DCE, and vinyl chloride from the 2Q 2025 groundwater monitoring report are given below, as well as a summary of VOC detections and an explanation of contaminant concerns from an unknown source (Wear Ever Alert).

 

   

    

 

References:

 

Groundwater Monitoring Report. Second Quarter Sampling Event, May 2025. Howmet Former Wear Ever Facility in Chillicothe, Ohio. October 2025. Prepared for: Howmet Aerospace, Inc. Prepared by: Key Environmental, Inc. ViewDocument.aspx

WearEver site remains a contaminated concern for Ohio EPA. Jay Salley, News Editor. Scioto Valley Guardian. January 13, 2025. WearEver site remains a contaminated concern for Ohio EPA

Toxic chemicals contained by the shuttering Chillicothe Pixelle plant could infect the air and groundwater. George Shillcock. WOSU. July 29, 2025. Chemicals contained by Pixelle plant could pollute air, groundwater - WOUB Public Media