SSP&A was retained to estimate and depict the lateral extent and the volume of radiologically-impacted material (RIM) within Areas 1 and 2 of Operable Unit 1 (OU-1) at West Lake Landfill Site, located in Bridgeton, St. Louis County, Missouri. This work was one step in the process of supporting the evaluation of potential remedy alternatives at the site.
SSP&A was involved in several geochemical evaluations at the Site, including:
- Interpretation of a select number of laboratory analyses conducted on specific “fate and transport” samples;
- Calibration of a source-term geochemical model describing the time varying leaching potential of uranium, thorium, and radium from RIM;
- Predictions of the transport and fate of radionuclides that may partition from the RIM into pore water within the Site and that have the potential to migrate toward the groundwater in OU-1; and
- Predictions of the transport and fate beneath OU-1 of any radionuclides that may reach groundwater.
SSP&A employed geostatistical methods to determine the extent and volume of RIM to determine the volume of both impacted and unimpacted soil to be removed in each potential excavation alternative, and to estimate mean and Upper Confidence Limits (UCLs) of the mean activity concentrations for radium and thorium in the excavated and non-excavated soil under each alternative to support the evaluation of risk associated with each alternative.
