Alternatives for Ground Water Cleanup (1994) / Chapter Skim
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B Glossary
B Glossary
Pages 285-298
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From page 285... ...
Alkane A chemical composed of a straight chain of carbon atoms bonded on all sides by hydrogen atoms and containing no double bonds between carbon atoms. The simplest alkane is methane.
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From page 286... ...
Capillary fringe zone The zone immediately above the water table. Carbonate A rock formed primarily from carbonate minerals, such as limestone and dolomite.
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From page 287... ...
These systems control the ground water flow direction around the contaminated site by using pumps, injection wells, and cutoff walls placed at strategic locations. Conventional pump-and-treat systems Systems that extract contaminated ground water and treat it at the surface.
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From page 288... ...
Dispersion is caused by diffusion and mixing due to microscopic variations in velocities within and between pores as well as by macroscopic velocity variations among zones of differing hydraulic conductivity. Dissolution The process by which solid or nonaqueous-phase liquid components of a contaminant dissolve in infiltration water and form a ground water contaminant plume.
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From page 289... ...
Because the oxygen supply in ground water is often limited, these bacteria can be important players in degrading subsurface contaminants. Feasibility study A study carried out at a hazardous waste site covered under the Comprehensive Environmental Response, Compensation, and Liability Act to determine possible remedies for contamination at the site.
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From page 290... ...
Hydraulic conductivity A measure of the volume of water at the existing kinematic viscosity that will move in a unit time under a unit hydraulic gradient through a unit area of medium measured at right angles to the direction of flow. Hydraulic containment See "Containment." Hydraulic gradient The change in head per unit distance in a given direction, typically in the principal flow direction.
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From page 291... ...
More precisely, it is the rate of discharge of ground water per unit area of the geologic medium per percentage volume of the medium occupied by voids measured at right angles to the direction of flow. Intrinsic permeability A measure of the relative ease with which a porous medium can transmit a liquid under a potential gradient.
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From page 292... ...
Nonenforceable health goals established under the Safe Drinking Water Act intended to protect against known and anticipated adverse human health effects with an adequate margin of safety. Technical feasibility is not considered in setting MCLGs.
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From page 293... ...
They may occur spontaneously when the appropriate chemicals are mixed, or they may be catalyzed by microorganisms. For example, when microbes degrade organic compounds, they may transfer electrons away from the compound, converting the compound to carbon dioxide and deriving energy from the electron transfer process.
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From page 294... ...
Record of Decision A document issued by the Environmental Protection Agency specifying the remedy for contamination at a site covered under the Comprehensive Environmental Response, Compensation, and Liability Act. Redox potential Describes the distribution of oxidized and reduced species in a solution at equilibrium.
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From page 295... ...
A study carried out at a hazardous waste site covered under the Comprehensive Environmental Response, Compensation, and Liability Act to determine the extent of contamination and the risk it poses. Residence time The average amount of time a fluid spends during transport through a unit volume of subsurface or a laboratory vessel.
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From page 296... ...
Safe Drinking Water Act The law, passed in 1974, that required the setting of standards to protect the public from exposure to contaminants in drinking water. Saturated zone The part of the subsurface that is beneath the water table and is saturated with water.
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An "electron donor substrate" may be thought of as a food source; the microbes degrade it to provide energy for cell growth. An "electron acceptor substrate" is oxygen or another substance that microbes use in the process of digesting the electron donor substrate; the organisms transfer electrons from the electron donor to oxygen (or another electron acceptor)
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From page 298... ...
Water table The "top" of the subsurface zone that is saturated with ground water. More precisely, it is the surface in an aquifer at which pore water pressure is equal to atmospheric pressure.
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