Three-dimensional analysis of future groundwater flow conditions and contaminant plume transport in the Hanford Site unconfined aquifer system: FY 1996 and 1997 status report

Abstract

et al. (1996) in support of the Environmental Restoration Program. However, the current three-dimensional model has resulted in higher estimates of peak concentrations at shallow depths and less vertical migration than was predicted in previous site-wide yodel applications. These discrepancies are attributable to differences in basic assumptions made about the hydrogeologic framework and the horizontal and vertical V discretization used in each model. The differences in assumptions resulting from each modeling approach affect lateral and vertical distributions of predicted hydraulic heads and contaminants in the unconfined aquifer.The near-term impacts of existing plumes to on-site drinking water supplies were examined by evaluating predicted concentration levels in the vicinity of identified on-site water supplies over the next Farm, will be impacted by future transport of these contaminants.vi

Addendum to Composite Analysis for Low-Level Waste Disposal in the 200 Area Plateau of the Hanford Site

“…4.120-4-123 in Kincaid et al 1998) predict an overall decline in the water table and accompanying changes (mainly declines and shifts) in hydraulic gradients within the operating areas and across the site. The different areas approach steady state at varying rates, as illustrated in Cole et al (1997). The areas north of the gap between Gable Butte and Gable Mountain along the Columbia River have the shortest time constants, and water levels in this region reach steady state by the year 2100.…”

“…For groundwater flow and saturated-zone transport of contaminants, an existing three-dimensional numerical model that has been developed for the Hanford Site unconfined Aquifer (Wurstner et al 1995;Barnett et al 1997;Cole et al 1997) was used. Predictions of groundwater flow in the unconfined aquifer focused on the response of the aquifer to the cessation of wastewater discharges from Hanford Site operations.…”

Uncertainty Analysis Framework - Hanford Site-Wide Groundwater Flow and Transport Model

“…Some excellent examples of modeling studies and investigations involving appropriate uses of a sitewide model and its general capabilities at the Hanford Site include recent modeling studies described in DOE Tank Waste Remediation System Environmental Impact Statement (TWRS EIS) 1994, DOE Hanford Remedial Action Environmental Impact Statement and Comprehensive Land-Use Plan (HRA EIS) 1996, Chiaramonte et al (1997), Cole et al (1997), and Kincaid et al (1998). A brief description of the each of these analyses and how a site-wide model was used is summarized in the following section.…”

“…In Cole et al (1997), a three-dimensional site-wide model of groundwater flow and transport was developed under the Hanford Groundwater Project to increase the understanding of contaminant transport on the Site and to better forecast the migration of the contaminant plumes being monitored by the project. The falling water table, resulting from the cessation of Hanford operations, is reducing the saturated extent of the highly conductive Hanford formation and is also causing the water table to move from the Hanford formation into mud units of the underlying Ringold Formation.…”

Evaluation of the Potential for Agricultural Development at the Hanford Site

“…The geology and hydrology of the Hanford Site have been studied extensively over the past 50 years (Cole et al 1997;Neitzel et al 1997). Geologically, the"Hanford Site lies within the Pasco Basin, a large structural depression that has collected a relatively thick sequence of fh.wial, Iacustrine, and glacio-fluvial sediments over the past several thousand years.…”