Revised Hydrogeology for the Suprabasalt Aquifer System, 200-East Area and Vicinity, Hanford Site, Washington

Williams, Bruce A.; Bjornstad, Bruce N.; Schalla, Ronald; Webber, William D.

doi:10.2172/991099

Cited by 54 publications

(76 citation statements)

References 23 publications

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“…A schematic representation of the 300 Area hydrogeologic column is shown in Figure 2.1. Reidel et al [1992], Lindsey [1995], Williams et al [2000] and DOE-RL [2002])…”

Section: Geologic Setting/hydrostratigraphymentioning

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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“…A schematic representation of the 300 Area hydrogeologic column is shown in Figure 2.1. Reidel et al [1992], Lindsey [1995], Williams et al [2000] and DOE-RL [2002])…”

Section: Geologic Setting/hydrostratigraphymentioning

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 hydrogeologic description for the 200-West and 200-East Areas presented below is taken primarily from Spane et al (2003), which is based on the following reports: Graham et al (1984), Lindsey et al (1992), Connelly et al (1992aConnelly et al ( , 1992b, Thorne et al (1993), Lindsey (1995), and Williams et al (2000).…”

Section: Hydrogeologic Settingmentioning

confidence: 99%

Results of Detailed Hydrologic Characterization Tests?Fiscal and Calendar Year 2005

Spane

Newcomer²

2008

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This report provides the results of detailed hydrologic characterization tests conducted within selected Hanford Site wells during fiscal and calendar year 2005. Detailed characterization tests performed included groundwater-flow characterization, barometric response evaluation, slug tests, in-well vertical groundwater-flow assessments, and a single-well tracer and constant-rate pumping test. Hydraulic property estimates obtained from the detailed hydrologic tests include hydraulic conductivity, transmissivity, specific yield, effective porosity, in-well lateral and vertical groundwater-flow velocity, aquifer groundwater-flow velocity, and depth-distribution profiles of hydraulic conductivity. In addition, local groundwater-flow characteristics (i.e., hydraulic gradient and flow direction) were determined for a site where detailed well testing was performed. Results obtained from these tests provide hydrologic information that supports the needs of Resource Conservation and Recovery Act waste management area characterization as well as sitewide groundwater monitoring and modeling programs. These results also reduce the uncertainty of groundwater-flow conditions at selected locations on the Hanford Site. v SummaryThe U.S. Department of Energy's Hanford Groundwater Monitoring Project, managed by Pacific Northwest National Laboratory, examines the potential for offsite migration of contamination within aquifer systems underlying the Hanford Site. An important characterization element that helps define the migration of contamination is the analysis of hydrologic tests, which provide estimates of hydraulic properties for the tested aquifer systems. Information gained from analyzing hydrologic tests is important when evaluating aquifer-flow characteristics (i.e., groundwater-flow velocity) and transport travel time, which are key parts of effective groundwater monitoring and modeling. Obtaining representative hydraulic-property information for the unconfined aquifer beneath the Hanford Site can be complicated by temporal changes in the water-table elevation and associated aquifer thickness. In particular, earlier hydrologic tests in the 200-West and 200-East Areas may reflect overlying, hydrogeologic units that are no longer saturated and are not part of the current groundwater flow system. Obtaining current information on hydraulic properties of the aquifer provides a way to assess the reliability and/or representativeness of earlier data and provides up-to-date information that can be used for effective groundwater monitoring and modeling.This report presents test results obtained from the detailed hydrologic characterization program of the unconfined aquifer system conducted for the Hanford Groundwater Monitoring Project during fiscal (FY) and calendar year (CY) 2005. Hydrologic tests conducted as part of the detailed program include the following:• slug testing (9 completed wells tested)• discrete depth interval slug testing (3 boreholes tested; with a total of 14 discrete-depth interval tests)• tracer-dil...

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“…Lindsey et al (2001) argued against a Plio-Pleistocene age for this gravel sequence, since Plio-Pleistocene-age gravels (informally named pre-Missoula gravels by PSPL [1982]) have previously been reported as "bleached" on the Hanford Site (Lindsey et al 1994). However, unbleached alluvial gravels of Plio-Pleistocene age are reported for the 200 East Area (Williams et al 2000) as well as south of the Hanford Site at Yakima Bluffs (Lindsey et al 1994). Furthermore, gravelly deposits recovered from beneath the PPlz unit in 299-E33-46 did not display all the characteristics listed above.…”

Section: 18mentioning

confidence: 99%

Characterization of Vadose Zone Sediment: Borehole 299-E33-46 Near B 110 in the B BX-BY Waste Management Area

Serne¹,

Bjornstad²,

Gee³

et al. 2008

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Executive SummaryThis report was revised in September 2008 to remove acid-ectractable sodium data from Table 4.17. The sodium data was removed due to potential contamination introduced during the acid extraction process. The rest of the text remains unchanged from the original report issued in December 2002.The overall goal of the of the Tank Farm Vadose Zone Project, led by CH2M HILL Hanford Group, Inc., is to define risks from past and future single-shell tank farm activities. To meet this goal, CH2M HILL Hanford Group, Inc., asked scientists from Pacific Northwest National Laboratory to perform detailed analyses on vadose zone sediment from within the B-BX-BY Waste Management Area. This report is the third in a series of three reports to present the results of these analyses. Specifically, this report contains all the geologic, geochemical, and selected physical characterization data collected on vadose zone sediment recovered from a borehole installed approximately 4.5 m (15 ft) northeast of tank B-110 (borehole 299-E33-46).This report also presents our interpretation of the data in the context of the sediment lithologies, the vertical extent of contamination, the migration potential of the contaminants, and the likely source of the contamination in the vadose zone and groundwater east of the B Tank Farm. The information presented in this report supports the B-BX-BY field investigation report prepared by CH2M HILL Hanford Group, Inc. (a) Overall, our analyses identified common ion exchange and heterogeneous (solid phase-liquid solute) precipitation reactions as two mechanisms that influence the distribution of contaminants within that portion of the vadose zone affected by tank liquor. We did not observe significant indications of caustic alteration of the sediment mineralogy or porosity, but we did observe slightly elevated pH values between the depths of 15 and 25 m (52 and 83 ft) bgs. X-ray diffraction measurements indicate no evidence of mineral alteration or precipitation resulting from the interaction of the tank liquor with the sediment. However, no scans of samples by scanning electron microscopy were performed that might suggest that there is faint evidence of caustic attack.Our analyses do not firmly suggest that the source of the contamination in the groundwater below and to the east of B Tank Farm is the 1971 transfer line leak at B-110. However, we are firmly convinced that the fluids from the transfer line leak event are present in the vadose zone sediments at borehole 299-E33-46 to a depth of 52 m (170 ft) bgs, within the Hanford H2 sand unit. Below this depth the concentration of nitrate still appears to be slightly elevated above natural background levels. There is also elevated technetium-99 between 68 and 69 m (222 and 226 ft) bgs in the Plio-pleistocene mud layer but we can't show that this contamination traveled through the entire vadose zone and in fact may have migrated horizontally from other sources. iv The near horizontally bedded, northeasterly dipping sediment likely caused hor...

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Revised Hydrogeology for the Suprabasalt Aquifer System, 200-East Area and Vicinity, Hanford Site, Washington

Cited by 54 publications

References 23 publications

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

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

Results of Detailed Hydrologic Characterization Tests?Fiscal and Calendar Year 2005

Characterization of Vadose Zone Sediment: Borehole 299-E33-46 Near B 110 in the B BX-BY Waste Management Area

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