40 CFR 436.181 - Specialized definitions.
For the purpose of this subpart:
(c) The term “10-year 24-hour precipitation event” shall mean the maximum 24 hour precipitation event with a probable reoccurrence interval of once in 10 years. This information is available in “Weather Bureau Technical Paper No. 40,” May 1961 and “NOAA Atlas 2,” 1973 for the 11 Western States, and may be obtained from the National Climatic Center of the Environmental Data Service, National Oceanic and Atmospheric Administration, U.S. Department of Commerce.
(d) The term “mine” shall mean an area of land, surface or underground, actively used for or resulting from the extraction of a mineral from natural deposits.
(e) The term “process generated waste water” shall mean any waste water used in the slurry transport of mined material, air emissions control, or processing exclusive of mining. The term shall also include any other water which becomes commingled with such waste water in a pit, pond lagoon, mine, or other facility used for settling or treatment of such waste water.