Variable thickness transient groundwater flow model theory and numerical implementation. [Radionuclide migration in ground water at Hanford]

Kipp, K.L.; Reisenauer, A.E.; Cole, C.R.; Bryan, Charles A.

doi:10.2172/7353122

Cited by 23 publications

(31 citation statements)

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“…Lindberg and Bond (1979) developed a Variable Thickness Transient (VTT) groundwater flow model of the 300 Area from a sub-region within the larger Hanford Project VTT model (Kipp et al 1972). These VTT models were two-dimensional (x-y) transmissivity finite difference models.…”

Section: Previous Modeling 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 Modeling 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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“…Early flow models were two dimensional (e.g., the Variable Thickness Transient [VTT] code) (Kipp et al 1972), and transport modeling, depending on application, was of the advective type (e.g., Hanford Pathline Calculation code) (Friedrichs et al 1977), quasi-three-dimensional particle tracking type (e.g., the Multicomponent Mass Transport [MMT] code) (Alhstrom et al 1977), or multiple streamtube type (e.g., the TRANSS code) (Simmons et al 1986). Early flow-models were calibrated with a stream-tube (a) ARC/INFO is a registered trademark of Environmental Systems Research Institute, Inc., Redlands, California.…”

Section: Chronology Of Site-wide Groundwater Model Developmentmentioning

confidence: 99%

Transient Inverse Calibration of Hanford Site-Wide Groundwater Model to Hanford Operational Impacts - 1943 to 1996

Cole¹,

Bergeron²,

Wurstner³

et al. 2001

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SummaryPacific Northwest National Laboratory has embarked upon a new initiative to strengthen the technical defensibility of and develop a more robust capability to incorporate uncertainty in the groundwater flow and transport model at the U.S. Department of Energy Hanford Site in Southeast Washington State. One aspect of the initiative is developing and using a three-dimensional transient inverse model approach to estimate the hydraulic conductivities, specific yields, and other site-wide scale parameters, including their uncertainties, by using data on the transient behavior of the unconfined aquifer system resulting from Hanford Site waste management since 1943. Over the historical period of Hanford operations, the large volumes of wastewater discharged to a variety of waste facilities resulted in large water table changes over most of the Hanford Site and created significant groundwater mounds (in excess of 20 m) under waste management facilities in the central part of the Site. Since 1988, the mission of the Hanford Site has changed from producing weapons to restoring the environment, and wastewater discharges have declined significantly, which has caused significant water table declines.The three-dimensional transient inverse calibration, which was recommended by an external peer review panel, is being performed using UCODE, a universal inverse modeling code developed jointly by the U.S. Geological Survey and the International Groundwater Modeling Center of the Colorado School of Mines. The work uses the existing consolidated site-wide groundwater model implemented with the Coupled Fluid Energy and Solute Transport code (CFEST), which is the forward model whose parameters are estimated by UCODE. The transient inverse calibration uses over 76,000 water level measurements taken in about 1200 wells at Hanford since the mid 1940s. Because of the long run times and large number of simulations, a serial computational approach for the coupled flow and transport inverse would require a year or more of computational effort. Thus we developed an innovative parallel computational approach that uses an isolated network of 23 computers. The approach uses a recently developed parallel version of UCODE that communicates with a parallel task manager to propagate the multiple simulation tasks (i.e., the forward model runs) for simultaneous computation on the dedicated computers. In addition, a customized version of the forward model code CFEST was developed to simplify the specification of inverse model parameters and the large number of observations. The existing consolidated site-wide groundwater model (referred to as the prior model in this report) was calibrated using 1979 data and a steady-state inverse approach in conjunction with trial and error transient model calibration runs using estimates of artificial discharges and a limited set of representative head observations taken between 1979 and 1996. The conceptual model for the prior model also provided the conceptual basis for the initial three-dimensional transien...

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“…A set of computer codes known as the Variable Thickness Transient (VTT) groundwater code (Kipp, et al, 1972) …”

Section: Code and Equipmentmentioning

confidence: 99%

“…Hanford is the Variable Thickness Transient Code (VTT) (Kipp et al, 1972 code, and a code developed by Intera Environmental Consultants (see Table III). The above codes are solved by the finite difference numerical technique, with the exception of CFEST, which uses the finite element scheme.…”

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confidence: 99%

A groundwater flow model of the aquifer intercommunication area, Hanford site, Washington

Simkover¹

2000

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Intercommunication has been identified between the unconfined and uppermost confined aquifer systems underlying a portion of the U.S. Department of Energy's Hanford Site. Erosional thinning and fracturing of the basalt confining layer within the study area allows physical contact between the two aquifers, but the vertical hydraulic gradient (a required driving force) is small. To better conceptualize the distribution and volume of the leakage occuring between the aquifer systems, this study investigates the confined Rattlesnake Ridge Aquifer flow system, which appears to be more sensitive to the vertical leakage than the overlying unconfined aquifer.

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Variable thickness transient groundwater flow model theory and numerical implementation. [Radionuclide migration in ground water at Hanford]

Cited by 23 publications

References 0 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

Transient Inverse Calibration of Hanford Site-Wide Groundwater Model to Hanford Operational Impacts - 1943 to 1996

A groundwater flow model of the aquifer intercommunication area, Hanford site, Washington

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