Numerical Modeling of Groundwater and Contaminant Transport at the MADE-2 Site PDF Download

Author: Dale F. Rucker
Publisher:
ISBN:
Category : Groundwater
Languages : en
Pages : 434

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Author: Mandar M. Sarangdhar
Publisher:
ISBN:
Category : Groundwater flow
Languages : en
Pages : 390

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 25

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Book Description
Public domain computer programs were used to attempt an improved model of the tritium plume observed during Macrodispersion Experiment 2 (MADE-2), a field scale natural gradient experiment conducted at Columbus Air Force Base, Mississippi. A computational grid having 66 rows, 21 columns, and 9 layers was used. The finite difference program MODFLOW was used to simulate the flow of groundwater through a 330 m x 105 m computational domain. Solutions for the 468 day experiment were obtained using a Sun Sparcstation 2 for several choices of convergence and storage parameters. The simulations had small mass balance errors and were consistent with continuous head observations. The smallest storage coefficients gave the best agreement. The flow model is about as accurate as the data permit. Tritium plume simulations used the mixed Lagrangian-Eulerian finite difference program MT3D to solve the contaminant transport equation using the MODFLOW-predicted flow field. Thirteen runs were made using various advection algorithms and dispersivities, but none was successful. Numerical instabilities or grossly unrealistic predictions ended every run by simulation day 141. Further work is needed to obtain a satisfactory plume prediction. (AN).

Author: Jacob Bear
Publisher: Springer Science & Business Media
ISBN: 1402066821
Category : Science
Languages : en
Pages : 851

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Book Description
In many parts of the world, groundwater resources are under increasing threat from growing demands, wasteful use, and contamination. To face the challenge, good planning and management practices are needed. A key to the management of groundwater is the ability to model the movement of fluids and contaminants in the subsurface. The purpose of this book is to construct conceptual and mathematical models that can provide the information required for making decisions associated with the management of groundwater resources, and the remediation of contaminated aquifers. The basic approach of this book is to accurately describe the underlying physics of groundwater flow and solute transport in heterogeneous porous media, starting at the microscopic level, and to rigorously derive their mathematical representation at the macroscopic levels. The well-posed, macroscopic mathematical models are formulated for saturated, single phase flow, as well as for unsaturated and multiphase flow, and for the transport of single and multiple chemical species. Numerical models are presented and computer codes are reviewed, as tools for solving the models. The problem of seawater intrusion into coastal aquifers is examined and modeled. The issues of uncertainty in model input data and output are addressed. The book concludes with a chapter on the management of groundwater resources. Although one of the main objectives of this book is to construct mathematical models, the amount of mathematics required is kept minimal.

Author: Ushashree Balla
Publisher:
ISBN:
Category : Groundwater
Languages : en
Pages : 280

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 213

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Book Description
Public domain computer programs were used to simulate groundwater flow and contaminant migration through a site at the Columbus Air Force Base Mississippi In the MADE-2 (Macrodispersion Experiment a pulse of dissolved contaminants in the saturated zone of an alluvial aquifer was monitored for 15 months. MODFLOW solved for head and seepage velocity for input to the transport code, MT3D. The contaminant transport equation was solved separately from the flow equation since buoyancy effects were assumed to be negligible. Initial simulations of the tritlum plume did not extend far enough from the injection site. An ad hoc assumption of horizontal anisotropy applied to the conductivity field produced good agreement with the observed plumes. Although the simulated plumes were realistic, the horizontally anisotropic conductivity field used to achieve these predictions was not. The principal axes were not aligned with the directions suggested by pump tests or geology, the anisotropy ratio was in excess of any previously observed, and the effective conductivity was above what had been measured at the site. The use of public domain software to model contaminant transport at heterogeneous sites is technically practical; but in the absence of exhaustive field measurements, little confidence can be placed in the predictions.

Author: Kenneth Y. Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 118

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Author: Mark Goltz
Publisher: John Wiley & Sons
ISBN: 0470242345
Category : Science
Languages : en
Pages : 272

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Book Description
Teaches, using simple analytical models how physical, chemical, and biological processes in the subsurface affect contaminant transport Uses simple analytical models to demonstrate the impact of subsurface processes on the fate and transport of groundwater contaminants Includes downloadable modeling tool that provides easily understood graphical output for over thirty models Modeling tool and book are integrated to facilitate reader understanding Collects analytical solutions from many sources into a single volume and, for the interested reader, shows how these solutions are derived from the governing model equations

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: National Research Council
Publisher: National Academies Press
ISBN: 0309106192
Category : Nature
Languages : en
Pages : 104

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Book Description
The world's first nuclear bomb was a developed in 1954 at a site near the town of Los Alamos, New Mexico. Designated as the Los Alamos National Laboratory (LANL) in 1981, the 40-square-mile site is today operated by Log Alamos National Security LLC under contract to the National Nuclear Security Administration (NNSA) of the U.S. Department of Energy (DOE). Like other sites in the nation's nuclear weapons complex, the LANL site harbors a legacy of radioactive waste and environmental contamination. Radioactive materials and chemical contaminants have been detected in some portions of the groundwater beneath the site. Under authority of the U.S. Environmental Protection Agency, the State of New Mexico regulates protection of its water resources through the New Mexico Environment Department (NMED). In 1995 NMED found LANL's groundwater monitoring program to be inadequate. Consequently LANL conducted a detailed workplan to characterize the site's hydrogeology in order to develop an effective monitoring program. The study described in Plans and Practices for Groundwater Protection at the Los Alamos National Laboratory: Final Report was initially requested by NNSA, which turned to the National Academies for technical advice and recommendations regarding several aspects of LANL's groundwater protection program. The DOE Office of Environmental Management funded the study. The study came approximately at the juncture between completion of LANL's hydrogeologic workplan and initial development of a sitewide monitoring plan.