[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: 40CFR61.204] [Page 147] 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. 61.204 Distribution and use of phosphogypsum for outdoor agricultural purposes. Phosphogypsum may be lawfully removed from a stack and distributed in commerce for use in outdoor agricultural research and development and agricultural field use if each of the following requirements is satisfied: (a) The owner or operator of the stack from which the phosphogypsum is removed shall determine annually the average radium-226 concentration at the location in the stack from which the phosphogypsum will be removed, as provided by Sec. 61.207. (b) The average radium-226 concentration at the location in the stack from which the phosphogypsum will be removed, as determined pursuant to Sec. 61.207, shall not exceed 10 pCi/g (4500 pCi/lb). (c) All phosphogypsum distributed in commerce for use pursuant to this section by the owner or operator of a phosphogypsum stack shall be accompanied by a certification document which conforms to the requirements of Sec. 61.208(a). (d) Each distributor, retailer, or reseller who distributes phosphogypsum for use pursuant to this section shall prepare certification documents which conform to the requirements of Sec. 61.208(b). (e) Use of phosphogypsum for indoor research and development in a laboratory must comply with Sec. 61.205. [57 FR 23317, June 3, 1992, as amended at 64 FR 5579, Feb. 3, 1999; 65 FR 62158, Oct. 17, 2000]