Variable thickness transient ground-water flow model. Volume 1. Formulation

Mathematical formulation for the variable thickness transient (VTT) model of an aquifer system is presented. The basic assumptions are described. Specific data requirements for the physical parameters are discussed. The boundary definitions and solution techniques of the numerical formulation of the system of equations are presented

Variable thickness transient ground-water flow model. Volume 3. Program listings

The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (OWNI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. Analysis of the long-term, far-field consequences of release scenarios requires the application of numerical codes which simulate the hydrologic systems, model the transport of released radionuclides through the hydrologic systems to the biosphere, and, where applicable, assess the radiological dose to humans. Hydrologic and transport models are available at several levels of complexity or sophistication. Model selection and use are determined by the quantity and quality of input data. Model development under AEGIS and related programs provides three levels of hydrologic models, two levels of transport models, and one level of dose models (with several separate models). This is the third of 3 volumes of the description of the VTT (Variable Thickness Transient) Groundwater Hydrologic Model - second level (intermediate complexity) two-dimensional saturated groundwater flow

Assessment of Effectiveness of Geologic Isolation Systems. Variable thickness transient ground-water flow model. Volume 2. Users' manual

A system of computer codes to aid in the preparation and evaluation of ground-water model input, as well as in the computer codes and auxillary programs developed and adapted for use in modeling major ground-water aquifers is described. The ground-water model is interactive, rather than a batch-type model. Interactive models have been demonstrated to be superior to batch in the ground-water field. For example, looking through reams of numerical lists can be avoided with the much superior graphical output forms or summary type numerical output. The system of computer codes permits the flexibility to develop rapidly the model-required data files from engineering data and geologic maps, as well as efficiently manipulating the voluminous data generated. Central to these codes is the Ground-water Model, which given the boundary value problem, produces either the steady-state or transient time plane solutions. A sizeable part of the codes available provide rapid evaluation of the results. Besides contouring the new water potentials, the model allows graphical review of streamlines of flow, travel times, and detailed comparisons of surfaces or points at designated wells. Use of the graphics scopes provide immediate, but temporary displays which can be used for evaluation of input and output and which can be reproduced easily on hard copy devices, such as a line printer, Calcomp plotter and image photographs

Calculation of soil hydraulic conductivity from soil--water retention relationships

A computer program has been written to solve the modified Millington and Quirk equation for computing the hydraulic conductivity curve for partially saturated soil from the moisture retention versus suction measurements. This document describes the equation and computer programs. It also shows plots of test results and compares them with physically measured data. (auth

MININR: a geochemical computer program for inclusion in water flow models - an application study

MININR is a reduced form of the computer program MINTEQ which calculates equilibrium precipitation/dissolution of solid phases, aqueous speciation, adsorption, and gas phase equilibrium. The user-oriented features in MINTEQ were removed to reduce the size and increase the computational speed. MININR closely resembles the MINEQL computer program developed by Westall (1976). The main differences between MININR and MINEQL involve modifications to accept an initial starting mass of solid and necessary changes for linking with a water flow model. MININR in combination with a simple water flow model which considers only dilution was applied to a laboratory column packed with retorted oil shale and percolated with distilled water. Experimental and preliminary model simulation results are presented for the constituents K/sup +/, Na/sup +/, SO/sub 4//sup 2 -/, Mg/sup 2 +/, Ca/sup 2 +/, CO/sub 3//sup 2 -/ and pH

Anticipated effects of an unlined brackish-water canal on a confined multiple-aquifer system

The major source of fresh water at Southport, North Carolina, is a confined multiple-aquifer groundwater system that can be affected in several ways by the proposed unlined cooling-water canal for the Brunswick nuclear power plant. The canal will route brackish water three miles from the Cape Fear Estuary to the plant condensers. The heated brackish effluent will then be routed six miles from discharge to the Ataantic Ocean. To evaluate the impact of the canal on the groundwater system, a mathematical model was used to describe steady-state responses resulting from a variety of conceivable hydrologic stresses. Numerical solutions were obtained by means of finite-difference approximations and a successive line overrelaxation solution technique. The model apprdximated three- dimensional saturated flow in aquifers of variable thickness by assuming two- dimensional flow in each aquifer with interaquifer transfer throughout the groundwater system. Simulation results indicated that saatwater from the estuary will eventually intrude upon Southport's municipal wells regardless of the presence of the proposed Brunswick canal. The canal system will not significantly decrease the time required for estuarine saltwater contamination of the wells. A major portion of the brackish water that downwells from the discharge canal appears to upwell in a parallel drainage channel west of the canal and in Dutchman Creek east of the canal. However, a low potential gradient toward the Southport wells is introduced by the downwelling portion of the discharge canal. This analysis did not consider the effect of the downwelling on the water quality of the Southport wells. However, saltwater movement along this gradient will require an order of magnitude more time to reach the wells than will saltwater intrusion from the estuary. Magnitudes and locations of upwelling and downwealing and the areal extent of the depression cones for the Southport wells wiaa be affected considerably by reducing the proposed operational water surface elevation in the discharge canal from +4.5 ft MSL to 0.0 ft MSL. (auth

Assessment of effectiveness of geologic isolation systems. Test case release consequence analysis for a spent fuel repository in bedded salt

Geologic and geohydrologic data for the Paradox Basin have been used to simulate movement of ground water and radioacrtive contaminants from a hypothetical nuclear reactor spent fuel repository after an assumed accidental release. The pathlines, travel times and velocity of the ground water from the repository to the discharge locale (river) were determined after the disruptive event by use of a two-dimensional finite difference hydrologic model. The concentration of radioactive contaminants in the ground water was calculated along a series of flow tubes by use of a one-dimensional mass transport model which takes into account convection, dispersion, contaminant/media interactions and radioactive decay. For the hypothetical site location and specific parameters used in this demonstration, it is found that Iodine-129 (I-129) is tthe only isotope reaching the Colorado River in significant concentration. This concentration occurs about 8.0 x 10/sup 5/ years after the repository has been breached. This I-129 ground-water concentration is about 0.3 of the drinking water standard for uncontrolled use. The groundwater concentration would then be diluted by the Colorado River. None of the actinide elements reach more than half the distance from the repository to the Colorado River in the two-million year model run time. This exercise demonstrates that the WISAP model system is applicable for analysis of contaminant transport. The results presented in this report, however, are valid only for one particular set of parameters. A complete sensitivity analysis must be performed to evaluate the range of effects from the release of contaminants from a breached repository