Light non-aqueous phase liquids

Testa, S. M., 1990, Light Non-Aqueous Phase Liquid Hydrocarbon Occurrence and Remediation Strategy, Los Angeles Coastal Plain, California In Proceedings of the International Association of Hydrogeologists, Canadian National Chapter, on Subsurface Contamination by Immiscible Fluids, April, in press. 

At Lawrence Livermore National Laboratory site 300, these compounds along with trichloroethylene (TCE) were used in heat-exchanger pipes at their materials testing facility [421-423]. Subsurface contamination by these compounds resulted from leaking heat-exchanger pipes. TBOS and TKEBS were present as light non-aqueous phase liquids whereas TCE was present as a dense... 

Dry Cleaning Site, Riverside, California. The PetroClean bioremediation system treated 2,000,000 gal of groundwater and light non-aqueous-phase liquid (LNAPL) at a total project cost of 270,000 (D10107L, pp. 8-12). 

In situ oil skimmers are commercially available for the recovery of free product [i.e., light non-aqueous-phase liquids (LNAPLs) such as oil, grease, or other hydrocarbons] floating on the water table. Oil skimmers can be used alone or in conjunction with other remediation technologies, such as (in situ) soil vapor extraction, bioventing, or bioremediation, or (ex sim) membrane filters, coalescers, or chemical processes. The technology is implemented in sim by lowering the skimmers into wells located in the zone of contamination. 

In 1996, OxyVac was used at a cement products manufacturing site in Salt Lake City, Utah, to treat 6400 to 14,000 yd of soil and sediment contaminated with VOCs. Groundwater and light non-aqueous-phase liquids (LNAPLs) were also treated to a depth of 7 to 15 ft in an area of 25,000 sft. Total costs at this site were 230,000 (D10341T, p. 16 D215751, pp. 13, 14). 

Waddill, D.W. and Parker, J.C. (1997). "Recovery of light, non-aqueous phase liquid from porous media Laboratory experiments and model validation." J. Contam. Hydrol, 27, 127-155. 

Suspension films separating two solid surfaces, and Wetting films separating a solid or liquid from a vapour. The minimum water content for which a small sample of soil or similar material will barely flow in a standardized test method. Also termed the upper plastic limit . See also Atterberg Limits, Plastic Limit, Plasticity Number. Light non-aqueous phase liquid. See Non-aqueous Phase Liquid. 

NAPL) Any liquid other than water. In environmental fields this term commonly refers to petroleum hydrocarbons less dense than water (light non-aqueous phase liquid, LNAPL), or oils such as chlorinated hydrocarbons that are more dense than water (dense non-aqueous phase liquid, DNAPL). 

Light non-aqueous phase liquids (e.g. petrol) and dense non-aqueous phase liquids (e.g. perchloroethylene) in an aquifer... 

Surfactants and microemulsion systems can be used for ex situ treatment of contaminated soil or in situ soil decontamination. In situ remediation is usually preferred if excavation of the contaminated soil is not possible or expensive, e.g. beneath buildings or for contaminations at great depth. Often bioremediation or natural attenuation is used for decontamination. In most cases, these techniques only permit the effective degradation of contaminants in the plume formed by dissolved pollutants which may be very large. However, for the remediation of a contaminated site, it is also necessary to remove the source where the pollutants maybe adsorbed in large quantities or may be present as solid or liquid phases. The latter are called NAPL (non-aqueous phase liquids) and a differentiation is made between LNAPL (light non-aqueous phase liquids) with a lower density than water and DNAPL (dense non-aqueous phase liquids) with a higher density than water (see Fig. 10.1). 

MTBE and TBA with densities of < 1 g/cm belong to the so called LNAPL (light non aqueous phase liquids) whereas CAH with densities of > 1 g/cm belong to the DNAPL (dense non-aqueous phase liquids). While DNAPL (heavy phase) tend to migrate as an independent phase in greater depths, LNAPL (light phase) float on the groundwater table. 

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