Facility Configuration and Construction Method
In addition to using hazard potential as a classification, impoundments and dams are also classified based on their configuration and development/construction staging. The disposal facility configuration is often dependent upon the terrain and storage size requirements, and the development staging reflects the general sequence or direction of disposal or construction activity.
Facility configuration categories are shown below. Each diagram is shown as a tailings dam or coal slurry impoundment storing solid waste. Each configuration may also be used to store water.
Cross-valley impounding embankment:
Side-hill impounding embankment:
Diked impounding embankment:
Many impoundments and dams used by the mining industry are constructed over many years as dictated by the rate of waste produced by the operation. Planning and design of an impounding embankment generally involves distinct development/construction stages that are associated with intermediate points in the facility construction and the general timing and directional development of the disposal operations. Each stage typically reflects a few months to a few years of disposal operation and usually reflects the direction in which development occurs. The direction of construction normally falls into two categories: upstream and downstream. Upstream construction involves initial construction and placement of embankment material in downstream areas to form the impoundment with sequential placement during subsequent stages in upstream locations, typically at higher elevations. Downstream construction involves initial construction and placement of embankment material in upstream areas with placement during subsequent stages in downstream locations. It is common to have both upstream and downstream construction stages as part of a disposal facility design. An intermediate development condition is centerline construction where stages are constructed both upstream and downstream of the previous stage, with the crest of the two stages generally in alignment, but separated by the elevation increment of the stage.
Downstream construction method:
Upstream construction method:
Centerline construction method: