In 2015, the U.S. Environmental Protection Agency (EPA) issued a new rule addressing the handling, storage and disposal of coal combustion residuals (CCRs). CCRs are the materials that remain after coal is burned.
Two Mitchell Plant ash storage sites are included in the CCR monitoring program:
- The bottom ash pond and
- The landfill.
Both storage sites are in active use. Mitchell Plant has switched to dry fly ash handling. The fly ash now is stored in a lined landfill.
In 2017, Mitchell Plant provided 627 tons of material from the bottom ash pond for beneficial reuse. Also in 2017, it provided 369,800 tons of gypsum - the CCR material produced through the process to remove sulfur dioxide from the plant’s flue gases - for beneficial reuse.
- Coal Combustion Residuals Monitoring & Reporting
Kentucky Power has completed the first steps in the new groundwater monitoring program under this rule
Kentucky Power took a series of groundwater samples at the boundaries of both ash storage sites. We took some samples before the groundwater passed beneath the ash storage sites. (The reports refer to this as up-gradient.) We took other samples after it passed beneath the sites (down-gradient). We used the data to establish baseline levels for 21 different substances in the groundwater. It is important to remember that variations in the level of these substances in groundwater are natural and occur for many reasons.
Moving forward, we will use these baselines to help determine if our ash storage sites are impacting the groundwater. We will watch to see whether there are changes in the amount of these substances before and after the groundwater flows beneath the ash storage sites. We also will watch whether levels of these substances vary from the baselines we observed.
The initial data at Mitchell Plant show potential groundwater impacts very close to our storage sites. Using appropriate sampling and analysis methods, we found differences in the amounts of boron, calcium, chloride and total dissolved solids in certain wells before and after the groundwater passed beneath the storage sites. The rule calls these indicator substances. They are used to determine whether additional analysis is needed.
Baseline sampling in some wells showed one or more results for arsenic and radium above primary drinking water standards. One or more samples showing a higher concentration of a substance, even above a standard, does not mean that local drinking water is unsafe or that there is any impact from the ash storage site.
We are working to understand what the numbers mean. We will do additional monitoring and analysis to determine if there are groundwater impacts from our storage sites farther from the immediate area.
We proactively reached out and met with plant neighbors and community leaders to answer questions about the data collected so far and to discuss next steps.
Here’s now Kentucky Power conducted the monitoring:
- The bottom ash pond - seven wells and
- The landfill - 13 wells.
- Alternate Source Reviews
Independent third parties completed Alternate Source Reviews for the bottom ash pond and landfill sites at Mitchell Plant. The reviews consider other factors that could impact sampling results as the groundwater passes the CCR storage sites.
This review process found alternate sources for groundwater impacts at Mitchell Plant’s landfill site. The plant will continue sampling groundwater at the landfill to determine any future need for additional monitoring.
An alternate source for groundwater impacts was not found for the bottom ash pond.
- Location Restrictions – New
The CCR rule established location restrictions for coal ash storage sites. It requires that storage site locations be evaluated regarding proximity to
- Groundwater aquifers,
- Fault areas,
- Seismic zones and
- Unstable areas (example: presence of quicksand).
AEP has completed the required review of location restriction for Mitchell Plant’s CCR storage sites. This review found that both CCR storage sites at Mitchell Plant meet all location restrictions.
- Next Steps
- Mitchell Plant will continue to test water from all of these wells twice each year.
- If plant owners determine that an ash storage site is impacting the groundwater, we will expand monitoring to show whether there are water quality impacts farther away from the storage site.
- If additional monitoring indicates that changes in groundwater quality are coming from our ash storage sites we will seek public input as we develop a mitigation plan to address these impacts.
- Bottom Ash Pond