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 Northeastern 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. Northeastern Plant now uses dry fly ash handling. Fly ash is stored in a lined landfill. The landfill has an “intermediate” liner. The landfill was not lined when it was first built. Northeastern Plant added the intermediate liner and now places all material over the liner.
In 2017, Northeastern Plant provided nearly 46,000 tons of CCR material for beneficial reuse.
- Coal Combustion Residuals Monitoring & Reporting
Public Service Company of Oklahoma (PSO) has completed the first steps in the new groundwater monitoring program under this rule.
PSO 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 Northeastern 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, chloride, fluoride, pH, sulfate 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, barium, beryllium, cadmium, chromium 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 how PSO conducted the monitoring:
- The bottom ash pond – six wells and
- The landfill – six wells.
- Alternate Source Reviews
Independent third parties completed Alternate Source Reviews for the landfill and bottom ash pond sites at Northeastern 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 Northeastern 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 and PSO recently completed the required review of location restrictions for Northeastern Plant’s CCR storage sites. This review found:
- The Northeastern bottom ash pond is separated from the uppermost aquifer by less than the five feet specified by the rule. It does meet the other four restrictions.
- The Northeastern landfill meets all location restrictions.
- Next Steps
- PSO will continue to test water from all of these wells twice each year.
- If PSO determines that the 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.
- Northeastern Plant has a closure date of no later than 2026. At that time, we will stop putting material into the bottom ash pond and the landfill and will begin closure activities.
- Bottom Ash Pond