Description of Source:
Phosphogypsum is a radioactive waste product that results from processing phosphate ore to make the phosphoric acid used in fertilizer. Phosphate ore contains uranium and radium. These radionuclides can be found in phosphogypsum, as well. Phosphogypsum is stored on site in large, aboveground piles, known as stacks. These stacks can emit large concentrations of radon gas to the ambient air.

This Subpart applies to phosphogypsum stack owners, phosphoric acid producers, agricultural users, and entrepreneurs who wish to use phosphogypsum in their research products.

The Standard: 
Each person who generates phosphogypsum shall place all phosphogypsum in stacks. Phosphogypsum may be removed from a phosphogypsum stack only as expressly provided in this Subpart. After a phosphogypsum stack has become an inactive stack, i.e., no further routine additions of phosphogypsum will be made, the owner or operator shall assure that the stack does not emit more than 20 picocuries per meter per second of Radon-222 into the air.

Reporting Requirements: 
Inactive stacks must be monitored and the results of emissions testing reported to EPA. If a stack ceases to be inactive, the owner or operator must notify EPA in writing. Emissions testing is required once the stack has become inactive again. Testing must be repeated at least once during each calendar year that the owner or operator removes additional phosphogypsum from the stack. In addition, the owner or operator of a stack from which phosphogypsum will be removed and distributed shall prepare a certification document for each quantity of phosphogypsum that is distributed in commerce.

More Information:
Electronic Code of Federal Regulations (e-CFE): 40 CFR 61, Subpart R
EPA Radiation Protection Division NESHAPs Home Page