Assessment of radiation contamination at an abandoned tin smelter facility in Galveston County, Texas

The Region 6 US Environmental Protection Agency (US EPA) and Technical Assistant Team (TAT) contractor, Ecology and Environment, Inc. (E and E), conducted a site assessment to determine the nature and extent of radiation contamination at an abandoned tin smelter facility in Texas City, Galveston County, Texas. Rapid, field-screening, radiation surveys were conducted, and four slag storage areas were located with gamma radiation levels above background levels. Comprehensive radiation surveys were performed at these locations with Global Positioning System (GPS) assistance for accurate location determination. Approximately 1,500 data points were collected from 10 acres. Accurate contour maps of gamma radiation levels were developed using geostatistical modeling and kriging. Radiation exposure levels ranged from background [< 10 microroentgen per hour (microR/hour)] to more than 500 microR/hour. Gamma spectroscopic analysis was performed on soil and slag samples using a field-portable, multichannel analyzer (MCA) system. Equilibrium activities of bismuth-214 and thallium-208 were measured as high as 100 picocuries per gram. Ten percent of all samples were sent to an independent radiochemistry laboratory for confirmation analysis. Laboratory and field screening results corresponded closely. In-situ radon emanation rates were measured with large area charcoal collectors (LACCs). Measured rates were less than one picocurie per square meter per second