Preparation of an Application for Approval to Use Stabilized Phosphogypsum as a Fill Material for Coastal Protection Devices
This report covers an application prepared to obtain approval from EPA for an alternate use of phosphogypsum (PG) in a “coastal protection device in the form of a mechanically stabilized embankment” consisting of PG briquettes and geotextile fabric with limestone or granite as armoring. The application was prepared in two sections: (1) an embankment with 350 metric tons of raw phosphogypsum on the shoreline of Lake Salvador, Louisiana and; (2) a test structure with 650 kg of PG in Lake Pontchartrain.
The calculated risk for all receptors is well below the EPA’s individual risk criteria of 1 × 10-4. The risk values were obtained using a very conservative approach that includes the possibility of a person digging part of the material from under the limestone armor, the geotextile bags and geogrid and consuming it. Also, the use of the embankment and test structure as fishing platforms and as 35% of the annual seafood consumption from the contaminated zone is considered.
The information included with this application provides evidence that the radiological risk associated with the use of PG as a fill material in coastal protection devices represents a lower health risk to public health than the
disposal in stacks.