Former Sodium Disposal Facility
The Former Sodium Disposal Facility (FSDF), formerly known as the "Sodium Burn Pit" operated from 1956 to 1978. The FSDF was built to treat waste sodium and NaK(a mixture of sodium and potassium). It was also used to react the sodium within various scrap test components (pumps, valves, etc.) before they were disposed of. Combustible liquid waste (oils, etc.) was also burned at the facility.
Components to be cleaned were placed on the slab, opened to expose the sodium and then washed off with water. Sodium ignites in the presence of moisture (hence the name 'burn pit'). After the components were washed, they were placed into unlined open pits where they were allowed to remain until residual sodium was reacted. The components were then retrieved and disposed of off-site as solid waste.
The sodium-water and NaK-water reactions also generated sodium hydroxide and potassium hydroxide, which subsequently react with carbon dioxide in the air to form sodium carbonate and potassium carbonate.
The Sodium Disposal Facility was never intended for use or disposal of radioactive materials, however it is clear that some contaminated equipment was taken to the facility. Subsequent surveys and soil sampling showed that the FSDF was both radioactively and chemically contaminated.
Following termination of operations at the FSDF in 1978, limited cleanup and removal of equipment and debris was performed in the late 1970s and 1980s. Periodic radiation surveys and soil samples indicated low levels of radioactive contamination, principally in the lower pond. A major characterization survey was performed in 1987.
In 1991, the California Regional Water Quality Control Board (RWQCB) issued an order under the California Toxic Pit Cleanup Act (TPCA) to remove all contaminated material from the lower pond. Rocketdyne performed a baseline radiological survey indicating only localized contamination. Following excavation of the lower pond in 1992, the RWQCB sampled the area to confirm that all contamination had been removed. All radioactive sample analysis indicated only background levels of radio-isotopes remained. In December, 1992, the RWQCB issued a letter documenting Rocketdyne's compliance and removed this site from the TPCA program.
In 1994, Rocketdyne completed excavation of the upper pond and other areas under the oversight of the California Department of Health Services (DHS) and the Department of Toxic Substances Control (DTSC). Upon completion of all excavation, Rocketdyne conducted a radiation exposure survey of the entire FSDF area including all the drainage channels. This survey was documented and submitted to the California DHS.
In 1995, soil samples from the upper pond, lower pond, western area and both drainage channels were independently analyzed by the Oak Ridge Institute of Science and Education (ORISE). ORISE concluded that the concentrations were below regulatory agency approved residential cleanup standards. A soil sample radiological analysis report was prepared and submitted to the California DHS in July 1996, with a request to release the facility for (radiologically) unrestricted use.
In August 1996, Rocketdyne published a factsheet on the status of the FSDF. The factsheet was titled "Speaking of The Santa Susana Field Laboratory - The Former Sodium Disposal Facility" and was mailed to a large number of the neighboring community to inform them of the cleanup process.
Additional testing conducted by DHS showed that no radiological contamination remained above background. In May 1998 the DHS removed the FSDF from California Radioactive Materials License 0015-19 and formally released the facility for (radiologically) unrestricted use. In November 1999, the final decommissioning report was prepared. In March 2000, the certification docket was completed.
More detail is provided in the Radiological History of the FSDF.
In 1999, additional soil was excavated from the upper pond as part of the RCRA Interim Measure in order to remove chemical contamination. In December 2000, the DHS and DTSC stated unequivocally that there was no radiological hazard from the FSDF soil, and stated that the soil could be legally and safely disposed of at a permitted Class I hazardous waste facility.
- Letter to Senator Boxer and Senator Kuehl from DHS and DTSC, December 2000
- Attachments to DHS/DTSC Letter
Efforts are being taken to understand the nature and extent of the impacts to groundwater beneath the FSDF and the area is included in the site-wide RCRA corrective action. DOE is working with DTSC to determine final remedy for the area and further cleanup may be required.
Several excavations, including a RCRA Interim Measure, removed all contaminated soils to bedrock. The soils were disposed of at an off-site landfill. In May 1998, the DHS removed the Sodium Disposal Facility from California Radioactive Materials License 0015-19, and formally released the facility for radiologically unrestricted use. The FSDF site was backfilled, graded, and landscaped to match the surrounding area in 1999. An interim measures report was submitted to the DTSC and additional work may be required under the RCRA corrective action program.