Code of Federal Regulations Title 40. Protection of Environment § 40.412.15 New source performance standards (NSPS)

(a) Except as provided in paragraph (b) of this section, any new source subject to this subpart must achieve the following performance standards:  There must be no discharge of process wastewater pollutants into U.S. waters.

(b) Whenever rainfall events cause an overflow of process wastewater from a facility designed, constructed, operated, and maintained to contain all process-generated wastewaters plus the runoff from a 25–year, 24–hour rainfall event at the location of the point source, any process wastewater pollutants in the overflow may be discharged into U.S. waters.