[Code of Federal Regulations]
[Title 40, Volume 26]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR421.42]

[Page 478]
 
                TITLE 40-PROTECTION OF ENVIRONMENT
 
      CHAPTER I-ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 421-NONFERROUS METALS MANUFACTURING POINT SOURCE CATEGORY--Table of Contents
 
          Subpart D-Primary Copper Smelting Subcategory
 
Sec. 421.42  Effluent limitations guidelines representing the degree of effluent reduction attainable by the application of the best practicable control 
          technology currently available.

    (a) Except as provided in 40 CFR 125.30 through 125.32 and paragraph 
(b) of this section, any existing point source subject to this subpart 
must achieve the following effluent limitations representing the degree 
of effluent reduction attainable by the application of the best 
practicable control technology currently available (BPT): There shall be 
no discharge of process wastewater pollutants to navigable waters.
    (b) A process wastewater impoundment which is designed, constructed, 
and operated so as to contain the precipitation from the 10-year, 24-
hour rainfall event as established by the National Climatic Center, 
National Oceanic and Atmospheric Administration, for the area in which 
such impoundment is located may discharge that volume of process 
wastewater which is equivalent to the volume of precipitation that falls 
within the impoundment in excess of that attributable to the 10-year, 
24-hour rainfall event, when such event occurs.