Managing CCR's

         The Coal Combustion Residual (CCR) Rule contains technical standards for the design, operation and closure of landfills and basins located at coal-fired energy centers.  Through this rule, EPA regulates CCR as solid waste under the Resource Conservation and Recovery Act (RCRA).  RCRA requires that CCR facilities operate in a manner that presents "no reasonable probability of adverse effect on health or the environment."  In 2016, Congress passed legislation that authorized states to develop CCR programs and adopt, as appropriate, site specific criteria.  In 2018 and in recognition of this congressional action, the Missouri General Assembly passed legislation authorizing the Missouri Department of Natural Resources (MDNR) to develop and submit a state CCR program to EPA for approval.

Also in 2018, EPA proposed revisions to the CCR Rule (Phase-One Rules) to address, in part, Congress's changes to RCRA and allow state directors to use risk-based processes similar to other existing solid waste program.  Both the State of Missouri and Ameren filed public comments that support EPA's proposed changes.  Copies of those comments can be accessed here.

EPA finalized the first phase of these CCR-related changes in July 2018, and the final phases are expected by summer 2019.  Until a state CCR program is finalized and approved by EPA, MDNR can utilize its state-level cleanup program to approve closure and corrective measures at Ameren's ash basins.


This ash basin at the Meramec Energy Center closed in the spring of 2018.

Read the report on our responsible management of coal combustion residuals.

Structural Stability Measures.

In 2008 and 2014 structural failures of surface impoundments at two energy centers in the southeastern United States resulted in the release of large quantities of coal ash slurry into adjacent rivers.  In one of those instances, the failure was largely the result of stacking coal ash well above the top of the basin embankment while the other was the result of a collapsed drainage pipe located beneath the basin. Following both incidents, Ameren voluntarily took steps to evaluate the physical condition of its facilities and to ensure ongoing safe operation. That assessment reflects that the various practices that contributed to the failure, including inappropriate storage and stacking of CCRs and inadequate foundations, were and are not present at Ameren's facilities.

A key to safe and secure management of CCR is by ensuring the integrity of landfills and ash basins.  The CCR Rule creates an evaluation process for existing CCR units and design standards for the construction of new units.  Plant operations staff inspect ash basins embankments weekly.  In addition, on an annual basis, we perform evaluations of all critical areas of the ash impoundments including embankment crest, interior and exterior slope, downstream toe area, and inlet/outlet works, etc.  Ameren's Dam Safety Program team regularly performs vegetation control, routine maintenance and erosion protection measures. As part of its CCR Rule compliance and to guard against the risk of structural failures, third-party engineering firms also perform specialized assessments at each of the energy centers, including hazard potential classification, structural stability, hydrologic and hydraulic capacity and safety factor determinations.  We also added video cameras to our inspection protocols to observe subsurface features such as piping and outlets. 

Ameren's basins and landfills are all protected by berms designed and maintained to withstand extreme weather events.  Third party engineers have performed modeling assessments to verify that the basins have sufficient retention capacity to hold a 100 year, 24 hour rainfall event. In addition, perimeter berms surrounding CCR landfills at our Sioux and Labadie Energy Centers are built to withstand a 500 year flood event.

Safe Drinking and Surface Water

Since 2012, Ameren Missouri has demonstrated that our coal combustion residual (CCR) management and disposal activities do not pose an adverse risk to public health and the environment. Reports have been prepared for all of Ameren Missouri's energy centers and can be accessed here. Each of the reports holds additional useful information about the local environment.

Labadie Energy Center
        Rush Island Energy Center
Meramec Energy Center
  Sioux Energy Center

Download an information sheet about Ameren Missouri's plans and progress. 

Water Resiliency Report. Ameren voluntarily participates in annual surveys regarding potential climate change risks including those related to water resources.  In 2018, Ameren engages an independent engineering firm to produce a Water Resiliency Report to assess water availability in our region and the Powder River Basin, a key portion of our supply chain.  That report is available here.

State Permits. Since the 1970s, ash basins have been categorized as water treatment facilities and as such are subject to Clean Water Act (CWA) requirements and state-administered permitting programs.  The CWA regulates discharges into surface waters (not groundwater) and publicly owned treatment works.  Industrial facilities such as power plants that discharge directly into surface waters must obtain and comply with NPDES permits and facility-specific pollutant discharge limits.  Ameren's ash basins at each of its energy centers are all lawfully permitted by MDNR and discharges from those basins into surface waters are specifically authorized by permit.  The permits not only contain very specific conditions that must be met, but also monitoring and reporting requirements that apply to the discharge.  Over the last decade, state environmental agencies began requiring groundwater monitoring and all of Ameren's energy centers now have monitoring requirements included in state operating water permits.

In Missouri, water quality is guarded through protection standards developed by state regulators. With respect to surface water, numerical limitations are placed in discharge permits as required by federal law. Effluent discharges into surface waters from Ameren's ash basins are all subject to numerical limits.  Groundwater is also subject to state protection standards for specific constituents and uses.  MDNR assigns "designated uses" to state water bodies, such as drinking water supply, irrigation, livestock and wildlife protection, and recreation. MDNR then designates water quality criteria to protect such uses.  Ameren monitors water quality at its energy centers by sampling groundwater through a system of onsite wells and surface water discharges from ash basins.  Ameren reports sampling data directly to MDNR as required by its permit.  In issuing permits, MDNR provides detailed descriptions and analysis of water quality requirements and facility operations.  Permits for all of our energy centers are posted on MDNR's website.

            CCR Rule.  Separate from state water permit obligations, we collect groundwater data as required under the federal CCR Rule, which imposes detailed requirements including specific public reporting obligations.  Consistent with those requirements, we have installed monitoring wells up- and down-gradient of CCR basins, which provide regular sampling for the presence of specific coal ash constituents.  Data is collected over several years to account for seasonal variations and will be used to establish protection standards through a statistical analysis protocol.  Due in part to background levels and site specific geochemistry, these protection standards can differ among energy centers.  We continue to collect and evaluate data to calculate the applicable protection standards required by the CCR Rule. Monitoring data collected in 2017 and the statistical analysis methodology used by Ameren are available here.

Ameren continues to collect data, including sampling to determine the nature and extent of any groundwater impacts.  Once those efforts are complete, Ameren will prepare reports that analyze the data and outline the extent of any observed impacts and appropriate corrective measures.  We anticipate completing those reports during the second quarter of 2019, after which we will host meetings to take public comments from interested stakeholders.

Ameren Missouri is stepping up efforts to increase recycling with up to 85 percent of future production put to beneficial use. CCRs can be used in the production of cement and concrete. It's likely the roads and highways you drove on today contain CCRs.

Detailed data and information for each of Ameren Missouri's coal-fired energy centers is publicly available, providing transparency to customers and stakeholders on Ameren Missouri's operations.

Ameren Has Conducted Extensive Environmental Evaluations at the Missouri Energy Center

Before the federal CCR rule, Ameren engaged multiple independent experts to evaluate groundwater and surface water quality at our energy centers. Copies of those reports are available here and contain the following information:

  •  Groundwater Flow – determined and plotted direction, flow rate and water level readings for all energy center sites on surface contour maps.
  • Public Water Supplies – identified the nearest location of public water supply intakes on the Missouri, Mississippi and Meramec Rivers. All such intakes are located miles from our facilities.
  • Residential Wells – identified private and community drinking water wells located within a one-mile radius of the energy centers.  In addition, Ameren installed offsite well networks at the Labadie and Rush Island Energy Centers to confirm that groundwater used by residential wells fully comply with drinking water standards.
  • Surface Water Sampling – sampled the Missouri, Meramec and Mississippi Rivers and adjoining creeks and backchannels to determine water quality and whether the ash basins impact those surface water bodies.
  • Risk Based Analysis – using flow rates for groundwater and surface water, calculated the concentration levels that would need to exist onsite before there could be an adverse impact to surface water.  As detailed in risk assessment reports prepared by Haley & Aldrich, for such an adverse impact to exist, onsite groundwater concentrations at each of the energy centers would need to be multiples higher than current conditions.

Haley & Aldrich also evaluated the groundwater and surface water data sets for the following potential exposures:  drinking water consumption, recreational use and fish consumption.  The analysis included more than 15,000 data points. Haley & Aldrich concluded, using EPA and MDNR published criteria, that the basins do not present either an ecological or human health risk. 

As detailed in the Haley & Aldrich 2018 reports, and under a risk-based analysis used by environmental regulators, for there to be a risk from a chemical constituent, there must first be a mechanism or physical pathway for such exposure to occur.  With respect to the ash basins, such a pathway does not exist thus there is no human exposure to groundwater impacted by coal ash constituents.  Concentration levels of certain constituents above drinking waterstandards do not equate to a health risk because a pathway of exposure, is absent. 

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