occurs naturally within some environments as part of the rock weathering process but is exacerbated by large-scale earth disturbances characteristic of mining and other large construction activities, usually within rocks containing an abundance of sulfide minerals. Areas where the earth has been disturbed (e.g. construction sites or highway construction) may create acid rock drainage.
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Note: ARD can occur naturally in undisturbed rock formations or be accelerated by excavation and exposure during construction, quarrying, or mining.
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