Nonaqueous phase liquids (NAPLs) are hydrocarbons that exist as a separate, immiscible phase when in contact with water and/or air. Differences in the physical and chemical properties of water and NAPL result in the formation of a physical interface between the liquids which prevents the two fluids from mixing. Nonaqueous phase liquids are typically classified as either light nonaqueous phase liquids (LNAPLs) which have densities less than that of water, or dense nonaqueous phase liquids (DNAPLs) which have densities greater than that of water. This issue paper focuses on transport, fate, characterization, and remediation of LNAPLs in the environment.

• Light Nonaquaeous Liquids (PDF)(28 pp, 250 K, 1995, 540-S-95-500)