A methodology for establishing cleanup objectives in the unsaturated soil zone using sensitivity and uncertainty analysis for chemical fate and transport

To support the Corrective-Measures and Cleanup-Alternatives Studies (CMS) p repared by Science Applications international Corporation (SAIC) at the Por tsmouth Gaseous Diffusion Plant (PORTS) in Portsmouth, Ohio, a soil-leachin g numerical analysis was conducted to help establish cleanup objectives for deep-soil contamination. For approximately 60 pollutants that exist at the PORTS site, the study defined those deep-soil concentrations that would mo st likely not cause groundwater contamination in excess of U.S. Environment al Protection Agency (USEPA) guidelines. These values were then used as the technical basis for defining soil-cleanup goals. Numerical modeling of env ironmental systems provides project managers with unique information that i s not available from other sources. With its ability to quantify the import ant aspects of problem physics, modeling allows one to rapidly accumulate t he physical insight needed to solve a problem in a systematic and focused m anner. This increased understanding acquired early in the planning stages o f a project permits managers to make decisions that are typically more thor ough, cost effective, and defensible. This article describes one such numer ical study conducted jointly by the Oak Ridge National Laboratory (ORNL) an d SAIC for the PORTS.