IIn support of CH2M HILL Hanford Group, Inc.'s (CHG) preparation of a Field Investigative Report (FIR) for the Hanford Site Single-Shell Tank (SST) Waste Management Area (WMA) B-BX-BY, a set of numerical simulations of flow and solute transport was executed to predict the performance of surface barriers for reducing long-term risks from potential groundwater contamination at the B-BX-BY WMA. This report documents the simulation of 14 cases involving two-dimensional cross sections through the B-BX-BY WMA. Two cross-sections were used for this analysis, one through the BX WMA from tanks BX-108 to BX-102, and another through the trench B-38 for simulating B trench discharges. The simulations were used to investigate the impact of surface barriers, water-line leaks, inventory placement, meteoric recharge and partitioning between the aqueous and sorbed phases. Three transported solutes were considered: uranium-238 (U-238), technetium-99 (Tc-99), and nitrate (NO3). For the BX tank simulations, results showed that simulations investigating water-line leaks demonstrated the highest peak concentrations. Interim barriers had a significant impact on peak concentrations in later times, but not in early times due to a high concentration zone of contaminants near the water table. Overall, simulation results for the BX WMA showed that only a small fraction of the U-238 inventory migrated from the vadose zone in most of the test cases. In general, similar peak WMA concentrations occurred for all of the simulations (
Revised: October 9, 2009 |
Published: August 25, 2002