Downtown in Soft Ground
Critchfield and MacDonald describe the shield excavation of twin bus tunnels 21.25 ft in diameter and 5,000 ft long as part of the Downtown Seattle Transit Project. This $450 million project,...

Simulation of Reactive Chemical Transport in a Varying Thermal Field with Reaction-Flow Coupling
A computer program, THCVP, simulates coupling between advective/diffusive solute transport and chemical reactions, coupling of the reactions to heat transport, and feedback from precipitation/dissolution...

Diffusion Barrier Transport Properties of Unsaturated Paintbrush Tuff Rubble Backfill
Diffusion coefficients (D) were experimentally determined in unsaturated tuff gravel to evaluated the effectiveness of tuff gravel and rubble as a diffusion barrier to ionic transport...

Three-Dimensional Plume Dynamics in the Vadose Zone: PORFLO-3 Modeling of a Defense Waste Leak at Hanford
In 1973, approximately 450 m3 of liquid containing radioactive and chemical wastes leaked from the 241-T-106 single-shell tank into the vadose zone...

Geochemical Modeling: An Integrated Approach to Nuclear Waste Disposal Issues
To meet nuclear waste repository licensing requirements, the response of repository components and of the enclosing host rocks and fluids to temperature fluctuations, fluid flow, radionuclide...

Diffusion Coefficients and Hydraulic Conductivity in Unsaturated Hanford Soils and Sediments
Two groundwater transport parameters of some Hanford formation materials, the hydraulic conductivity and the diffusion coefficient, were measured to aid in predicting contaminant migration....

Properties of the West Valley Waste Form
The centroid composition of the West Valley Demonstration Project waste form has been selected on the basis of criteria mandating high chemical durability and good processibility. A review...

Characteristics of Potential Repository Wastes
The U.S. Department of Energy is responsible for the eventual disposal in a repository of spent fuels, high-level waste, and other radioactive wastes that may require long-term isolation....

Effects of Water Composition on the Dissolution Rate of UO2 Under Oxidizing Conditions
Dissolution rates were measured on crushed unirradiated UO2 fuel pellet samples under oxidizing conditions using a flow-through testing method. Water...

Renovating the Riverside Water Plant?A Case Study
In 1986, the City of Waco, Texas began construction of the first of four projects designed to renovate the Riverside Water Treatment Plant. The water treatment plant was originally constructed...

A Rational Basis for Determining Safety of Containment
Design of waste containment facilities may follow one of three tacts: (1) the liner and cover systems may have prescribed components of predetermined minimum thicknesses and hydraulic...

Effects & Risk Analysis for Time Variable Exposures
The effects of toxicants on organisms in natural settings are a function of both the variations in exposure concentrations and duration of exposure. This paper present analysis procedures...

Unmixing Mixed Waste
A thermal treatment process successfully converted sludge classified as hazardous chemical/radioactive mixed waste to low specific activity radioactive waste at the National Guard Armory...

Remediating A Fire Site
Machin and Ehresmann describe remediation of a 15 acre fire site at Fort Huachuca, Ariz. An investigation after the fire showed that all of the debris contained asbestos. Sampling confirmed...

Factors Affecting Neutron Gauge Calibration
Neutron gauge characteristics and soil chemistry affect gauge calibration. External factors also influence gauge calibration and should be considered in the calibration procedure. Gauge...

Relationship of Soil Type and Chemicals to the Calibration of Neutron Meters
Theory of neutron scattering and moderation in matter explains many of the characteristics of calibration curves of neutron moisture probes. Characteristics include effect of atomic species...

Research Needs in Movement of Agricultural Chemicals to Groundwater
Better prediction of the movement of agricultural chemicals to groundwater is necessary to permit development of best management practices to reduce adverse environmental effects of agriculture....

Geochemical Factors Affecting Trace Element Mobility
Selected geochemical processes to be considered when modeling the movement of trace elements in soils are presented. The topics covered include: solid phase-solubility equilibria, ion...

Application of the U.S.G.S. DHM for Floodplain Analysis
The two-dimensional Diffusion Hydrodynamic Model, DHM, is applied to the evaluation of floodplain depths resulting from an overflow of a leveed river. The environmental concerns of flood...

Thermal Plumes from Staged Diffusers into a Uniform Quiescent Environment
The behavior of thermal plumes from staged multiport diffusers was investigated experimentally. The three-dimensional temperature distribution was measured by scanning thermistor rakes...

 

 

 

 

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