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Under a contract with Washington Group International (WGI) for the USACE
Tulsa District, Pangea completed the remediation of an abandon
radioactive waste burial site located in Waco, Texas. Burial activities
at the site occurred during the 1940s and 1950s, when the property was
under the ownership of the United States Air Force. Solid radioactive
waste was placed in 12-foot deep concrete-walled disposal wells or
“tubes.” The tubes were constructed of concrete pipe, approximately
twenty-four inches in diameter with 6-inch outer walls and plugs of
concrete at either end of the tube. The tubes contained small
radioactive items, such as radium-painted dials and gauges, electron
tubes, small test objects, and other contaminated equipment. Pangea
completed the safe removal and disposition of the disposal tubes
including: radiation protection and monitoring; waste characterization;
waste profiling; waste profiling; and the transportation and disposal of
the wastes.
Due
to the uncertainties about the integrity of the burial tubes and the
activity levels of the contents, special procedures were developed to
keep the tubes intact during excavation and removal operations. Soil
excavation occurred in 1-foot lifts so the tubes could be inspected and
allow for characterization of the soils at each stage of the excavation.
A combination of gamma walkover surveys and soil sampling/analysis was
used to characterize the soils.
Characterization of the internal contents of the disposal tubes was
accomplished by using a combination of gamma spectroscopy and activity
mapping. Using these methodologies made it possible to determine the
activities, concentrations, and isotopes of the waste contained within
the disposal tubes. It also allowed for effective characterization of
the wastes while minimizing disposal costs by utilizing local landfills
and in-state disposal facilities. A final walkover survey was conducted
in conjunction with WGI and the State regulatory authorities, following
the excavation of the tubes.
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