Site Overview

The Zimmer site, located along the Ohio River near Moscow, Ohio, consists of a retired power plant that no longer produces electricity and a permitted landfill.

Today, the company continues to operate the landfill facility that is about three miles from the retired power plant site, where it manages materials associated with past operations and other authorized sources.

Low-angle view of a cooling tower with beige concrete support columns at the base, against a pale sky.
Current Operations
Industrial power plant with cooling tower and smokestack reflected in calm water, surrounded by green hills and yellow wildflowers.
FAQ
A cargo ship sailing on a river, with a forested hillside in the background and the sunlight reflecting on the water.
History

Current Operations

Current Site Status

The Zimmer Power Plant began commercial operation in 1991 and was retired on May 31, 2022, and is no longer generating power.

Ongoing work at the former power plant site focuses on land management, environmental monitoring, and regulatory compliance.

Landfill Operations

The Zimmer landfill site became operational in 1991 when the plant began generating power. It is a permitted residual waste landfill consisting of multiple engineered cells, a leachate collection system, treatment ponds, and groundwater monitoring systems. The facility was designed, constructed, and continues to operate in accordance with applicable permits and regulatory requirements.

The landfill and associated sedimentation ponds were designed and engineered in accordance with state-issued permits. These engineered features are intended to contain permitted byproducts from coal combustion. Landfill operations have remained consistent: there have been no material changes in recent years.

An aerial view of a water treatment plant with circular sedimentation tanks and a long conveyor system, surrounded by dense green trees and a river in the background.
An aerial view of a water treatment plant with circular sedimentation tanks and a long conveyor system, surrounded by dense green trees and a river in the background.

    • Older landfill sections include a mixture of fly ash, bottom ash, and stabilized FGD byproducts, among other materials associated with coal-fired power generation.

    • Newer landfill sections include stabilized FGD byproducts, along with inert (non-hazardous and odorless) material from the nearby operational Miami Fort Power Plant. The inert materials are a limestone-based byproduct composed primarily of naturally occurring substances, including silica and river sediment. No coal ash is currently transported from the Miami Fort facility to the landfill. 

    • The inert limestone-based byproducts are transported by truck from Miami Fort. These trucks typically use a dedicated haul road for transport to and from the landfill– this is not a mandate or restriction; it is a practice instituted voluntarily by the site.

  • The Zimmer site is operated in accordance with applicable permits and regulations.  

    Regulatory compliance:

    • The site continues to operate under federal, state, and local environmental permits and requirements. More information can be found on the company’s public coal combustion residuals (CCR) reporting website.  

    Ongoing monitoring:  

    • Conditions at the landfill site are closely monitored in accordance with state and federal requirements. 

    • Ohio EPA has periodically conducted ambient air monitoring to evaluate concerns raised by the public with the site, including in July 2026. 

    • The company regularly communicates with federal, state, and local regulatory agencies, including the Ohio EPA, about landfill operations. 

    Routine evaluation for improvement:

    • We routinely evaluate and implement opportunities to enhance the performance of environmental controls. 

  • At times throughout the landfill’s operation, low levels of odors have been observed near the site. The company has installed and operates odor-mitigation systems.

    • Understanding the Science:

      • Odors can occur when rainwater or moisture interacts with landfill materials, producing a liquid byproduct known as leachate. This liquid is a typical byproduct of landfill operations that can produce an odor at times.

      • The leachate is collected and managed onsite within a sedimentation pond as part of normal operations in compliance with our permits.

    • Variability:

      • Intermittent odor near the landfill can result from water or leachate collecting in the sedimentation pond.

      • Odor intensity can vary significantly based on weather conditions, temperature, humidity, and wind direction, among other factors.

    • Investing in Odor Mitigation:

      • Over the years, the company has implemented a series of odor-mitigation systems and technologies designed to reduce odor levels.

        • Examples of improvements include:

          • Pond aeration systems installed and upgraded

          • Perimeter air neutralization systems installed and upgraded

          • Carbon filtration system installed and upgraded

          • Periodic sedimentation pond dredging

      • These systems operate continuously and are monitored routinely and adjusted as needed.

      • New technologies continue to be evaluated and tested.

  • Vistra engages with officials, community stakeholders, and area residents about the site.

    • The company communicates with officials and regulatory agencies regarding site conditions and community questions.

    • Monitoring, testing, and evaluation efforts are ongoing to ensure the site continues to operate safely and in compliance with regulations.