Potential Impacts of Leakage from Black Rock Reservoir on the Hanford Site Unconfined Aquifer: Initial Hypothetical Simulations of Flow and Contaminant Transport
Description: Initial scoping calculations of the unconfined aquifer at the Hanford Site were carried out for the U.S. Bureau of Reclamation (USBR) to investi¬gate the potential impacts on the Hanford unconfined aquifer that would result from leakage from the proposed Black Rock Reservoir to the west. Although impacts on groundwater flow and contaminant transport were quantified based on numerical simulation results, the investigation represented a quali¬tative assessment of the potential lateral recharge that could result in adverse effects on the aquifer. Because the magnitude of the potential leakage is unknown, hypothetical bounding calculations were performed. When a quantitative analysis of the magnitude of the potential recharge from Black Rock Reservoir is obtained, the hydrologic impacts analysis will be revisited. The analysis presented in this report represent initial bounding calculations. A maximum lateral recharge (i.e., upland flux) was determined in the first part of this study by executing steady-state flow simulations that raised the water table no higher than the elevation attained in the Central Plateau during the Hanford operational period. This metric was selected because it assumed a maximum remobilization of contaminants that existed under previous fully saturated conditions. Three steady-state flow fields were then used to analyze impacts to transient contaminant transport: a maximum recharge (27,000 acre-ft/yr), a no additional flux (365 acre-ft/yr), and an intermediate recharge case (16,000 acre-ft/yr). The transport behavior of four radionuclides was assessed for a 300 year simula¬tion period with the three flow fields. The four radionuclides are current contaminants of concern (COCs) in the Central Plateau and include tritium, iodine-129, technetium-99, and uranium-238. Transient flow and transport simulations were used to establish hypothetical concentration distributions in the subsurface. Using the simulated concentration distributions in 2005 as initial condi¬tions for steady-state flow runs, simulations were executed to investigate the relative effects on contam¬inant transport from ...
Date: March 9, 2007
Creator: Freedman, Vicky L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department