Prairie State Energy Campus Near Field CCR Monofill

Project Summary

The Prairie State Energy Campus near Marissa, Illinois, is comprised of a 1,600-megawatt power generation facility, adjacent coal mine and on-site monofill. The power plant came online in 2012 and has been producing energy on behalf of its member- owners to supply power to more than 2.5 million families and businesses across the Midwest and Mid-Atlantic region. Prairie State’s mine produces nearly 6.5 million tons of coal each year. As a byproduct of energy production, the campus generates coal combustion residuals, or CCRs.

Prairie State’s CCR monofill, Near Field, provides the facility with more than 30 years of storage for any of the CCR material that is not beneficially reused.

Hanson provided design and development for the monofill, including:

  • A composite liner system consisting of a 3-foot, compacted, low-permeability soil layer and a 60-mil, high-density, polyethylene (HDPE) geomembrane.
  • A composite final cover system consisting of a 1-foot, compacted, low-permeability soil layer, a 40-mil HDPE geomembrane and a 3-foot protective soil layer.
  • A leachate management system.
  • A surface water management system.
  • Groundwater, leachate and surface water monitoring, as necessary. 

The monofill has been designed with multiple cells; construction and filling of the cells will be staged over the life of the facility. Subcells may be developed to limit the size of active areas. Temporary separation berms will be constructed between cells and subcells to protect the underlying composite liner prior to developing the adjacent cell. This will be done to control surface water run-on to the active disposal area as a way of minimizing leachate generation and maintaining environmental compliance.

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