Non aqueous phase liquids

Villaume, J.F., Investigations at sites contaminated with dense non-aqueous phase liquids (DNAPLs),... 

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. 

Maguire, T. F., 1988 Transport of a Non-Aqueous Phase Liquid within a Combined Perched and Water Table Aquifer System In Proceedings of the National Water Well Association of Ground Water Scientists and Engineers FOCUS Conference on Eastern Regional Ground Water Issues, September, 1988. 

Villume, J. G. 1985, Investigations at Sites Contaminated with Dense Non-Aqueous Phase Liquids (NAPLs) Ground Water Monitoring Review, Spring, Vol. 5, No. 2, pp. 60-74. 

Conner, J. A., Newell, C. J., and Wilson, D. K., 1989, Assessment, Field Testing and Conceptual Design for Managing Dense Non-Aqueous Phase Liquids (DNAPL) at a Superfund Site In Proceedings of the National Water Well Association and American Petroleum Institute Conference on Petroleum Hydrocarbons and Organic Chemicals in Groundwater Prevention, Detection, and Restoration, November, pp. 519-533. 

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... 

Weber WJ, Mukherji S, Peters CA, (1998) Aqueous dissolution of constituents of composite non-aqueous phase liquid contaminants. In Rubin H, Nakis N, Carberry J (eds) Soil and aquifer pollution. Springer, Heidelberg pp 123-135... 

Foams are being investigated as a technology for site remediation applications. Foams may be used to treat non-aqueous-phase liquids in the soil subsurface. Foams could be used to deliver gases, surfactants, chemicals, nutrients, and bacteria to the subsurface. 

The Ferox process offers several potential advantages over conventional permeable barrier walls. For example, Ferox injection parameters may be modified to reflect the contaminant concentration heterogeneities present at most dense non-aqueous-phase liquid (DNAPL) sites. Unlike permeable walls, Ferox is not limited to the treatment of dissolved-phase contaminants and may be applied under structures. In addition, Ferox is not limited by depth and does not require the use of excessive quantities of iron powder. 

Bioslurping is a commercially available, in situ technology that combines vacuum-enhanced free-product recovery with bioventing of subsurface soils to simultaneously remediate petroleum-hydrocarbon-contaminated groundwater and soils. Vacuum-enhanced recovery utilizes negative pressure to create a partial vacuum that extracts free product and water from the subsurface. Bioventing is forced aeration to accelerate in situ bioremediation of hydrocarbons and non-aqueous-phase liquids (NAPLs). 

In situ chemical oxidation using potassium permanganate was also demonstrated to treat dense, non-aqueous-phase liquid (DNAPL) at the Canadian Forces Base Borden in Ontario, Canada, between 1996 and 1997. This application used a series of six injection and five oxidant recovery weUs. The total cost of the project was approximately 45,000 (D18766A, p.l3). 

Waterflood oil recovery is a commercially available, in situ techuology for the treatment of groundwater contaminated with dense non-aqueous-phase liquids (DNAPLs) such as oil. Water-flood oil recovery is tailored to specific site conditions and is generally used in conjunction with barrier technologies. All information is from the vendor and has not been independently verified. 

Cosolvent flushing is an in situ technology that enhances the remediation of contaminated soils and groundwater by injecting water and a cosolvent such as alcohol (e.g., ethanol, methanol, and isopropyl) into a contaminated area. Research has shown that an organic cosolvent can also accelerate the movement of metals through a soil matrix. The alcohol causes both an increase in aqueous contaminant solubility and lowering of non-aqueous-phase liquid (NAPL)-water interfacial tension. 

SPSH has several advantages. It is applicable to sites where contaminants are present as non-aqueous-phase liquids (NAPLs). The technology reduces volatile organic carbon (VOC) removal time to a few weeks for a typical site, whereas soil vapor extraction (SVE) alone requires years for remediation. This reduction in removal time can signrhcantly decrease costs over SVE (from 2 to 10 times). Excavation and ex situ soil treatment is typically much more expensive to implement than SPSH, especially at deep sites. 

CESAR was developed to address the problem of locating, characterizing, and removing dense non-aqueous-phase liquids (DNAPLs) from contaminated aquifer systems. The process is particularly suited to remediating groundwater contaminated with chlorinated solvents, such as trichloroethylene (TCE), tetrachloroethene (PCE), trichloroethane (TCE), and carbon tetrachloride (CCE). According to the vendor, CESAR can also be applied to sites contaminated with creosote, polychlorinated biphenyls (PCBs), Freon 113, volatile organic compounds (VOCs),... 

Costs for CESAR vary greatly, depending on site characteristics, the amount of dense non-aqueous-phase liquid to be solubilized, the depth of the aquifer, the amount and concentrations of clay and many other considerations (D137560, p. 238). 

According to the vendor, remediation activities cost 1200/gal to remove dense non-aqueous-phase liquids from groundwater at the Hill Air Force Base in Utah (D14795Z, p. 1). 

The process of anaerobic biotransformation with steam injection is a technology for the in situ remediation of soils and groundwater contaminated with dense non-aqueous-phase liquids (DNAPLs). Using this approach for remediation, steam is injected into the soil to volatilize and remove DNAPLs, with the simultaneous introduction of nutrients. The resulting subsurface conditions are suitable for biotransformation of the dissolved phase, into compounds that are more easily removed by vapor and groundwater extraction. 

Electrokinetics has been used to mobilize metals and dissolved contaminants to in situ treatment or recovery zones. Electrokinetic transport uses these mechanisms to move bacteria through the subsurface to the contaminated media. The technology can be used to treat organic contaminants that adsorb to aquifer soils including halogenated hydrocarbons and non-aqueous-phase liquids (NAPLs). 

Reclaim is commercially available and suitable for the recovery of VOCs, vinyl chloride, trichloroethylene, carbon tetrachloride, dense non-aqueous-phase liquid (DNAPL) compounds, and, in particular, petroleum hydrocarbons. The vendor states this technology has been used in a wide variety of industrial applications, such as the remediation of groundwater at service stations, dry cleaners, herbicide production facilities, and municipal and industrial landfills, among others. 

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. 

Soil vapor extraction (SVE) (also called vacuum extraction, soil venting, or in situ vaporization) is used to remove volatile organic compounds (VOCs) and some semivolatile organic compounds (SVOCs) from contaminated soil. SVE systems apply a vacuum in an extraction well to remove soil vapors. This creates a negative pressure that causes the volatilization of some chemicals in the vadose zone of the soil. The technology has also been used to extract non-aqueous-phase liquid (NAPE). Contaminant volatilization is often enhanced through the use of air injection wells to supply unsaturated air into the vadose zone of the soil. 

ISOTEC was chosen to treat soils contaminated with dense non-aqueous-phase liquids (DNAPLs) at a Superfund site in Florida. With a projected cost of 340,000, ISOTEC was cheaper than the alternative technologies considered. The estimated cost for implementing six-phase heating at the site was 535,000, and the estimated cost for excavation and ex situ treatment was 835,000 (D21478I, pp. 10, 11). 

Abbreviations TCE, trichloroethylene DCE, dichloroethylene PCE, perchloroethylene TCA, trichloroethane cDCE, cis-dichloroethylene DNAPL, dense, non-aqueous-phase liquid. 

TERRA-PURE is an in situ technology that ntihzes a flushing system for extraction of contaminants from soil. According to the vendor, it is applicable to organic and inorganic contaminants present at relatively high concentrations and to non-aqueous-phase liquids. 

The vendor states that tetrachloroethane (PCE), trichloroethene (TCE), and other volatile compounds are difficult to remove from saturated soils because they are relatively insoluble. The vendor states that the technology is especially applicable to sites contaminated with dense non-aqueous-phase liquids (DNAPLs). Using the ISSZT technology creates an unsaturated zone from which these contaminants can be readily air stripped. Other contaminants such as polychlorinated biphenyls (PCBs) or metals can be isolated from groundwater and contained within barriers preventing the spread of contamination. 

The process can be applied to the cleanup of source areas such as dense pools of non-aqueous-phase liquid (NAPL) below the water table surface, light NAPL pools floating on the water table surface, and NAPL contamination remaining after conventional pumping techniques. Subsurface conditions after application of the thermal process are generally amenable to biodegradation of residual contaminants. 

During the field demonstration in 1997 at the Department of Defense s (DOD s) Operable Unit 2, Hill Air Force Base in Utah, approximately 908 gal of dense, non-aqueous-phase liquids (DNAPLs) were removed from contaminated soils. The cost of the demonstration was 230/yd of soil treated and 165/gal of DNAPL removed. These costs included the purchase of all the equipment and an extensive monitoring network. It is estimated that future applications at the site would require roughly half as many wells and the boiler rental would be restricted to a much shorter period. These conditions would lower the direct treatment costs to 103/yd of treated soil and 74/gal DNAPL removed (D18518W, p. 216). 

Detergent Extraction of Non-Aqueous-Phase Liquids in the Subsurface (DeNAPLs)... 

Steam injection and vacuum extraction (SIVE) is a patented, commercially available in situ technology. SIVE has been used to remove non-aqueous-phase liquids (NAPLs), diesel fuel, jet fuel, semivolatile and volatile organic compounds (SVOCs and VOCs), chlorinated solvents, acetone, and benzene, toluene, ethyl benzene, and xylenes (BTEX) from soil and ground-water. 

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