Spoil bank
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The term "spoil bank" or spoil tip refers to a pile of refuse, created by excavation of earth materials from a site, or by removing excess surface materials from a site.
Common usages of the term
Most commonly the term is used for the piles of waste earth materials removed during an excavation process.
- In surface mining (commonly called strip mining) for coal or other underground deposits, earth materials removed to expose the targeted deposit are piled up alongside the excavation site (commonly a strip mining pit) in spoil banks.
- A dredge in placer mining is used to dig up volumes of gravel and other earth materials which are then sent through sluices to remove gold or other minerals, and the remaining earth materials("tailings") are deposited behind the dredge in spoil banks.
- In hydraulic mining high-pressure jets of water dislodge earth materials which are put through sluices to sort out gold or other minerals, and the residuary earth materials are left in spoil banks.
- The excavation of ditches and canals results in spoil banks being left along the side of the canal or ditch.
Spoil banks can also refer to refuse heaps formed from removal of excess surface materials. For example, alongside livestock lots spoil banks are formed of manure and other slurry periodically removed from the surface of the livestock lot areas.
Similar terms
In England the term "spoil heap" or "pit bank" is used for the pile of refuse of excavation from a coal mine, or open coal pit.[1]
Etymology
The phrase originates from the French word "espoilelier", a verb conveying the meaning: to seize by violence, to plunder, to take by force.[2]
Environmental issues
Spoil banks are closely related to environmental issues. During the industrial revolution era mining activity was generally unregulated in the United States, and spoil banks produced by mining activities were first generated, then left behind when the mining effort became unprofitable and the site was abandoned. These mining sites in general and the spoil banks in particular have produced environmental problems over years, which include surface runoff of silt, and leaching of noxious chemical compounds from spoil banks exposed to weathering. These cause contamination of ground water, and other problems.[3][4] Today in the United States forward-looking state and federal mining regulations require that the earth materials from excavations be removed in such a fashion that they can be replaced after the mining operations cease in a process called mine reclamation, with oversight of mining corporations, including requiring adequate reserves of monetary bonds to guarantee a completion of the reclamation process when mining becomes unprofitable or stops. (See for example, Surface Mining Control and Reclamation Act of 1977).