The Waste Isolation Pilot Plant A Potential Solution for the Disposal of Transuranic Waste (1996) / Chapter Skim
Currently Skimming:
F. REGIONAL HYDROGEOLOGY
F. REGIONAL HYDROGEOLOGY
Pages 134-142
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 134... ...
Although it is obvious that the properties of a regional aquifer must be defined with some accuracy in order to permit reliable predictions of ground-water flow and transport, it may be less clear that it is also necessary to define accurately the boundary conditions, recharge, and discharge in order to fully define and calibrate a mode} of the aquifer system. Studies of regional aquifer systems are most comprehensive when the study area extends to the natural geologic or hydrologic boundaries of the system and includes as much of the natural recharge and discharge areas of the system as possible.
|
From page 135... ...
Conceptual Errors Conceptual errors are derived from theoretical misconceptions about the basic processes, dimensionality, and/or boundary conditions that are incorporated in the model. Conceptual errors include neglecting relevant processes and representing inappropriate ones.
|
From page 136... ...
As long as the sources of numerical errors are recognized and the magnitude of the error is controlled, the solution may be sufficiently accurate for use. The solute-transport equation is in general more difficult to solve accurately using numerical methods than is the ground-water flow equation, largely because the mathematical properties of the transport equation vary depending on which terms in the equation are dominant in a particular situation.
|
From page 137... ...
Although flow may be predominantly horizontal, some vertical components of flow and transport undoubtedly exist, and they may significantly affect the flow, transport, travel times, and concentration distributions in the Culebra in areas downgradient from a potential release. Fractures are the high-permeability avenues (or pathways)
|
From page 138... ...
If future climate change induces greater diffuse recharge to the water table, then the saturated thickness of the Dewey Lake Red Beds may increase significantly, resulting in greater transmissivity values and higher flow velocities. Since the recharge would likely retain a relatively low content of dissolved solids, use of the Dewey Lake as a drinking water source might increase significantly in the future.
|
From page 139... ...
Recent controlled field experiments and theoretical advances in the study of transport processes indicate that large-scale (macroscopic) dispersion results largely from spatial variations in velocity, caused by spatial variations in hydraulic conductivity and effective porosity (see Gelhar et al., 1992~.
|
From page 140... ...
The differences in conceptualization must not yield inconsistencies in the effective surface area of fractures per unit volume of aquifer between the field estimates and the PA models, because such inconsistencies might affect the calculated rates of matrix diffusion. Overestimates of the amount of plume spreading can occur if the assumed dispersion coefficients are too large or if assumed patterns of heterogeneity artificially induce divergence of flow.
|
From page 141... ...
They state that "an extreme case is where the fracture skins have zero permeability and porosity so that no interchange of fluids, colloids and solutes between the fracture and the matrix is possible." Analytical methods are available to interpret the results of tracer tests conducted in fractured aquifers having skin effects (see Moench, 1984; Sharp et al., 1995~. The presence of a skin effect would render meaningless any projections of matrix diffusion rates based solely on the physical properties of the matrix.
|
From page 142... ...
A recently published review of transport of reactive contaminants in heterogeneous media concludes that "the transport of reactive solutes appears to be influenced most greatly by subsurface heterogeneity and rate-lim~ted mass transfer interactions" (Brusseau, 1994, p.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.