Interim characterization report for the 300 Area process trenches

Schalla, Ronald; Wallace, Roger.; Aaberg, R.L.; Airhart, S.P.; Bates, D.J.; Carlile, J.V.M.; Cline, C.S.; Dennison, D.I.; Freshley,; Heller, Ph.

doi:10.2172/6676561

Cited by 41 publications

(62 citation statements)

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“…1.2 1.4 Lindberg and Bond (1979), Schalla et al (1988), Gaylord and Poeter (1991), and Swanson et al (1992) performed early studies on the hydrogeologic characterization of the 300 Area. The hydrogeologic framework of the 300 Area was recently updated in a limited field investigation (LFI) of the 300 Area performed in fiscal years (FY) 2006).…”

Section: Previous Studiesmentioning

confidence: 99%

Three-Dimensional Groundwater Models of the 300 Area at the Hanford Site, Washington State

Williams¹,

Rockhold²,

Thorne³

et al. 2008

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iii Executive SummaryThe purpose of this research is to develop and maintain numerical groundwater flow and transport models that can be used to refine the conceptual site model for groundwater beneath the 300 Area, and to assist in evaluating alternative remediation technologies focused on the 300 Area uranium plume. Groundwater flow rates and directions in the 300 Area are very dynamic because of the high hydraulic conductivities, along with the large daily, weekly, and seasonal fluctuations in the Columbia River stage. Quantifying the dynamics of groundwater flow and transport in the 300 Area aquifer will help understand the significant seasonal variability of uranium plume concentrations seen in biannual groundwater monitoring, and will help evaluate remediation options. Groundwater flow rates are very high in the upper portion of the 300 Area unconfined aquifer (within the Hanford formation), with velocities up to 10 to 15 m/d (35 to 50 ft/d) based on a tracer test and limited plume-migration data. Variability in the groundwater-flow directions is apparent from analysis of hourly and subhourly automated water-level measurements from monitoring networks established in the 300 Area. Generalized flow directions in the area between the north and south process ponds are toward the east to south, with the directions changing toward the south and west during periods of increases in the river stage (daily and seasonal).High-resolution water level and river stage data were required to simulate the dynamics of the 300 Area aquifer. Two scales of groundwater flow and transport models were developed based on the availability of high-resolution water-level monitoring data. A larger-domain model was developed that includes the 300 Area and extends north and south using data from the early 1990s water-level monitoring network. A smaller domain model was developed for a portion of the large scale model domain in the north of the 300 Area that used water-level data from another smaller monitoring well network that was established in 2004. These models focus on the highly permeable upper portion of the unconfined aquifer within the Hanford formation that has hydraulic conductivity values 2 to 3 orders of magnitude higher than the underlying Ringold Formation aquifers. These models simulate saturated and unsaturated groundwater flow and transport with the STOMP code, which was developed at Pacific Northwest National Laboratory. 1The hydrostratigraphy, topography, and bathymetry for the three-dimensional models used a consistent framework using EarthVision  software.The model domains include the lower portion of the vadose zone to encompass the range of river stage and water- The hydrostratigraphic units were determined from previously published interpretations of the 300 Area, along with data from additional wells installed since those studies. A reanalysis of some of the older geologic unit picks from well logs in the area, along with using geophysical logs, was conducted based on the detailed knowledge gained from the 300 ...

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Section: Previous Studiesmentioning

confidence: 99%

Three-Dimensional Groundwater Models of the 300 Area at the Hanford Site, Washington State

Williams¹,

Rockhold²,

Thorne³

et al. 2008

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“…The brief discussion that follows highlights the similarities and differences in the geologic and hydrogeologic properties of these geologic layers, ordered from oldest to youngest. The information presented is a summary from previous reports (e.g., Lindberg and Bond 1979;Schalla et al 1988;Gaylord and Poeter 1991;Swanson et al 1992;Thorne et al 1993;Lindsey 1995) and recent reports (Williams et al 2007). …”

Section: Geologic Setting Of the 300 Areamentioning

confidence: 99%

“…Gaylord and Poeter (1991) report that the Hanford formation is generally coarser grained (larger gravels), less cemented and compacted, and does not have extensive fine-grained lithofacies as compared to the Ringold Formation. Previous and ongoing studies have concentrated on defining the two and three-dimensional surface of the Ringold contact in the 300 Area, including the area in the immediate vicinity of the Columbia River shoreline (e.g., Lindberg and Bond 1979;Schalla et al 1988;Gaylord and Poeter 1991;Swanson et al 1992;Thorne et al 1993;Lindsey 1995;Williams et al 2007). …”

Section: Observations and Measurements Of The Ringold Contactmentioning

confidence: 99%

Investigation of the Hyporheic Zone at the 300 Area,Hanford Site

Fritz¹,

Kohn²,

Gilmore³

et al. 2007

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SummaryAt the Hanford Site in southeastern Washington State, contaminated groundwater discharges to the Columbia River after passing through a zone of groundwater/river water interaction at the shoreline (i.e., the hyporheic zone). In the hyporheic zone, river water may infiltrate the riverbank during periods of high-river stage and mix with the approaching groundwater. Contaminants carried by groundwater may become diluted by the infiltrating river water, thus reducing concentrations at locations of exposure, such as riverbank springs and upwelling through the riverbed. There have been limited studies of contaminant concentrations, physical properties, or the extent of the hyporheic zone near the Hanford Site's 300 Area, yet this zone is a major interface for discharge of groundwater contamination into the Columbia River.The Remediation Task of the Remediation and Closure Science Project conducts research to meet several objectives concerning the discharge of groundwater contamination into the river at the 300 Area of the Hanford Site in Washington State. This report documents research conducted to meet these objectives by developing baseline data for future evaluation of remedial technologies, evaluating the effects of changing river stage on near-shore groundwater chemistry, improving estimates of contaminant flux to the river, providing estimates on the extent of contaminant discharge areas along the shoreline, and providing data to support computer models used to evaluate remedial alternatives. This report summarizes the activities conducted to date, and provides an overview of data collected through July 2006. Recent geologic investigations (funded through other U.S. Department of Energy [DOE] projects)have provided a more complete geologic interpretation of the 300 Area and a characterization of the vertical extent of uranium contamination. Extrapolation of this geologic interpretation into the hyporheic zone is possible, but little data are available to provide corroboration. Penetration testing was conducted along the shoreline to develop evidence to support the extrapolation of the mapping of the geologic facies. While this penetration testing provided evidence supporting the extrapolation of the most recent geologic interpretation, it also provided some higher-resolution detail on the shape of the layer that constrains contaminant movement. Information on this confining layer will provide a more-detailed estimate of the area of riverbed that has the potential to be impacted by uranium discharge to the river from groundwater transport.Water sampling in the hyporheic zone has provided results that illustrate the degree of mixing that occurs in the hyporheic zone. Uranium concentrations measured at individual sampling locations can vary by several orders of magnitude depending on the Columbia River and near-shore aquifer elevations. This report shows that the concentrations of all the measured constituents in water samples collected from the hyporheic zone vary according to the ratio of groundwater and C...

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“…The sites represented include the 300 Area (Schalla_1997_D.mdb), BC Cribs and Trenches (SVSoils_BCCrib_D.mdb), the ILAW site (SVSoils_ILAW_D.mdb), the Sisson & Lu Site (SVSoils_S&L_D.mdb), a clastic dike study site (SVSoils_VZTFFY03_D.mdb), and a compilation of data generated by the Westinghouse-Hanford Co. Geotechnical Engineering Lab (SVSoils_Freeman_D.mdb). The data in Schalla_1997_D.mdb represent data reported by Schalla et al (1988), collected more than 20 years ago, that were previously available only in hardcopy. These and other historical data were entered by hand into Excel spreadsheets and/or into SoilVision ® .…”

Section: Physical and Hydraulic Properties Databasementioning

confidence: 99%