Dense Non-aqueous Phase Liquid - A contaminant that is denser than water and exists as an isolated "plug."

liquid contaminants that are relatively insoluble and heavier than water; also known as sinkers because they will sink to the bottom of an aquifer, where they become especially difficult to detect and clean up

See non-aqueous phase liquid.

One of a group of organic substances that are relatively insoluble in water and more dense than water. DNAPLs tend to sink vertically through sand and gravel aquifers to the underlying layer.

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.