40 CFR 440.148 - Best Management Practices (BMP).
The following best management practices are specific requirements which shall be included in each NPDES permit for all mining operations regulated under this subpart to the greatest extent applicable in each such mining operation.
(a) Surface water diversion: The flow of surface waters into the plant site shall be interrupted and these waters diverted around and away from incursion into the plant site.
(b) Berm construction: Berms, including any pond walls, dikes, low dams and similar water retention structures shall be constructed in a manner such that they are reasonably expected to reject the passage of water.
(c) Pollutant materials storage: Measures shall be taken to assure that pollutant materials removed from the process water and wastewater streams will be retained in storge areas and not discharged or released to the waters of the United States.
(d) New water control: The amount of new water allowed to enter the plant site for use in ore processing shall be limited to the minimum amount required as make-up water for processing operations.
(e) Maintenance of water control and solids retention devices: All water control devices such as diversion structures and berms and all solids retention structures such as berms, dikes, pond structures and dams shall be maintained to continue their effectiveness and to protect from unexpected and catastrophic failure.