A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Decontamination: Removal of harmful substances such as noxious chemicals, harmful bacteria or other organisms, or radioactive material from exposed individuals, rooms and furnishings in buildings, or the exterior environment.

Degree-Day: A rough measure used to estimate the amount of heating required for a give period; useful to estimate possible oil consumption rates for a given time period.

Delineation:  Methodology used to define the lateral and vertical extents and the severity of contamination in the environment. 

Dense Non-Aqueous Phase Liquid (DNAPL): Non-aqueous phase liquids such as chlorinated hydrocarbon solvents or petroleum fractions with a specific gravity greater than 1.0 that sink through the water column until they reach a confining layer. Because they are at the bottom of aquifers instead of floating on the water table, typical monitoring wells do not indicate their presence.

Density: A measure of how heavy a specific volume of a solid, liquid, or gas is in comparison to water. depending on the chemical.

Detection Limit: The lowest concentration of a chemical that can reliably be distinguished from a zero concentration.

Direct Push: Technology used for performing subsurface investigations by driving, pushing, and/or vibrating small-diameter hollow steel rods into the ground/ Also known as direct drive, drive point, or push technology.

Discharge: Flow of surface water in a stream or canal or the outflow of ground water from a flowing artesian well, ditch, or spring. Can also apply to discharge of liquid effluent from a facility or to chemical emissions into the air through designated venting mechanisms.

Downgradient: The direction that groundwater flows; similar to "downstream" for surface water.

Drawdown: 1. The drop in the water table or level of water in the ground when water is being pumped from a well. 2. The amount of water used from a tank or reservoir. 3. The drop in the water level of a tank or reservoir.

Duplicate: A second aliquot or sample that is treated the same as the original sample in order to determine the precision of the analytical method. (See: aliquot1.)

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z