The Coal Combustion Residuals (CCR) and Effluent Limitations Guidelines (ELG) regulations have many overlapping impacts on the operation of coal plants, primarily concerning ash ponds and their discharge. First, the ELG rule requires zero discharge of any ash transport water and places stringent limits on the metals contained in the discharge of FGD wastewater. This will most likely require modifications to bottom ash systems as well as the implementation of FGD wastewater treatment systems at many plants. Secondly, the CCR rule requires closure of any ash pond that is found to violate groundwater protection standards or is unable to meet the location restrictions outlined in the rule.
Getting Started for Settlement Compliance
There are many factors that can affect a CCR/ELG compliance project, and most electric utilities are working to develop a phased project definition study that outlines the scope, implementation schedule and budget for their compliance solution. An integrated, holistic plan is required for this effort, and should include:
- Water balance verification with flow measurements and constituent sampling
- Bottom ash conversion technology evaluations
- FGD system optimization and wastewater treatment technology evaluations
Major Changes to Address for Compliance
Ash ponds are typically the heart of a power plant’s water balance. Think of the ash transport water and the FGD wastewater as about 40% of the flow routed through a facility. These flows are segregated and the discharges either treated or eliminated in order to comply with ELG.
One of the most challenging aspects of overall regulatory compliance will likely include the handling of remaining non-CCR flows after these streams are removed. Non-CCR flows generally include landfill leachate, coal pile runoff, site stormwater, boiler blowdown, demineralizer regeneration wastes, RO reject, cooling tower blowdown, plant drains and other low-volume wastewaters.
Some luck utilities will be allowed to continue routing non-CCR flows to their ash pond, providing all of the CCR rule requirements can be satisfied by their facility. Even if these requirements are met, the discharge water quality from the facility will be impacted once any ash sluice flows are removed from the overall water balance.
A few utilities are focusing on these non-CCR streams, and these impacts should not be overlooked by others. One potential solution involves the construction of a new water balance pond prior to any ash pond closure. Many factors affect the design of this new water balance pond including anticipated discharge limits, water quality for the remaining streams, particle size analysis, overall residence time and available site footprint.
Similar ponds or tank-based treatment solutions will likely be required at many facilities nationwide as we move further down the path of CCR compliance. Utilities should include the cost and schedule for this modification as they develop compliance plans for each plant’s compliance plan. Doing so will help establish the proper ELG compliance date for each facility, and prevent cost overruns during the project execution phase.