[Code of Federal Regulations]
[Title 40, Volume 8]
[Revised as of July 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR61.201]

[Page 145-146]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 61_NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS
--Table of Contents
 
     Subpart R_National Emission Standards for Radon Emissions From 
                          Phosphogypsum Stacks
 
Sec. 61.201  Definitions.

    As used in this subpart, all terms not defined here have the meaning 
given them in the Clean Air Act or subpart A of part 61. The following 
terms shall have the following specific meanings:

[[Page 146]]

    (a) Inactive stack means a stack to which no further routine 
additions of phosphogypsum will be made and which is no longer used for 
water management associated with the production of phosphogypsum. If a 
stack has not been used for either purpose for two years, it is presumed 
to be inactive.
    (b) Phosphogypsum is the solid waste byproduct which results from 
the process of wet acid phosphorus production.
    (c) Phosphogypsum stacks or stacks are piles of waste resulting from 
wet acid phosphorus production, including phosphate mines or other sites 
that are used for the disposal of phosphogypsum.