CCR management systems and wet impoundments have been a focus at coal-fired facilities due to mandates by the EPA and state regulations regarding the disposal or storage of byproducts. RECON’s CCR management solution is to first stabilize wet impoundment materials in-place, and then develop a landfill for dry CCRs on top of the now dry, stabilized CCR materials. This process not only meets or exceeds regulations, but also provides a cost-saving alternative when compared to new land requirements, landfill permitting, cell development with liners, and dig and haul removal of wet CCRs. The following stages describe RECON’s general process of using an existing CCR wet impoundment as the footprint for a dry CCR landfill cell.
Stage 1: Mass Impoundment Stabilization
RECON begins the process by performing stabilization of CCRs after the water on the impoundment has been removed. The CCRs are stabilized to increase strength and decrease permeability as required. By using RECON’s patented reagent blend in-situ (LSS®) or a utility’s own CCRs, RECON is able to stabilize the pond by introducing appropriate pozzolanic reactions to produce a low-cost stabilized monolith base. Once the material is cured, the monolith provides a structural foundation to access heavy equipment on and build the landfill for the dry CCRs. Vertical wick drains can be installed through the CCRs, if necessary, to provide a means of dewatering and consolidating CCRs based on geotechincal engineering design. Depths of solidification can be modified depending on engineering designs, states’ regulations, and a utility’s internal policy requirements or risk assessment. In some cases, full depth stabilization is not required.
Stage 2: Perimeter Impoundment Stabilization
The perimeter is then reinforced using deep soil mixing techniques to meet engineered design requirements for vertical expansion, as specified by clients’ engineering firm, and prevent any slip-plane failure potential.
Stage 3: Constructing the Landfill
Once the wet CCRs have been stabilized and meet all performance criteria, construction of the landfill begins according to engineered design. The landfill’s perimeter dike is raised to increase vertical space and then is followed by the installation of appropriate liners inside the cell. CCR regulations will require well monitoring systems that may include leak detection piping and sumps to monitor possible leaching from new deposits.
Stage 4: Filling the Landfill
After construction of the landfill that meets all requirements of the EPA CCR regulation requirements, it is ready to accept dry CCR deposits. Along with RECON’s 25 years of experience with landfill construction and development, RECON also has the expertise to provide the day-to-day operations of CCR handling, beneficial use applications, and landfill management.
Eventual Cap and Cell of Landfill
Once the landfill has met its maximum volume (depending on the projected operations of the plant) the landfill is ready to be graded, capped, and revegetated for long-term maintenance. The surface area can then be beneficially used for recreational purposes, such as a park or laydown yard in case the plant undergoes a major turnaround or expansion.
CCR Impoundment Advantages
- In-place stabilization is more cost effective when compared to CCR conditioning, removal through dig and haul operations and the costs associated with new landfill development. Calculated savings approach 20% to 30% or more depending on the facility characteristics.
- In-situ stabilization mitigates risk to utilities and provides a significant buffer from spills on roadways during transportation and other risks associated with trucking over public roads. Keeping the CCRs in place and on site significantly insulates the utility from ENGO targeting and will likely be a preferred method for most state EPD regulations.
- Building a landfill over former CCR impoundments maximizes use of space, thereby reducing the footprint that would be required for new landfills and may be the only alternative to plants that are landlocked or lack acreage for new fills.
- RECON has the ability to specialize its equipment fleet to meet the demands of deep soil mixing and in-situ stabilization, and RECON has the technical expertise to formulate the proper mix designs to create impermeable monoliths with existing wet CCRs. Our specialize fleet sets us apart from most general contractor and incumbent ash management services.