COAL COMBUSTION RESIDUE

The CCR ash at the Rosebud Power Plant is deposited while it is dry using a belly dump trailer pulled by a water tank truck. The ash is a pozzolanic material that contains both anhydrous calcium sulfate (CaSO4) and unreacted calcium oxide (CaO), also known as quicklime or unslaked lime. Both compounds have a strong chemical affinity to absorb water, forming a mixture of hydrated calcium sulfate (CaSO4-2 H2O, also known as gypsum) and hydrated lime (Ca(OH)2, also known as slaked lime). The purpose of adding water to the dry ash is to control fugitive dust and to form a solid mortar/concrete-like compound from the ash. Due to the nature of material and how it is stored, the CCR landfill at the Rosebud Power Plant minimizes the potential for CCR releases to the environment.

Also known as: CCR