Evaluation of in situ cosolvent flushing dynamics using a network of spatially distributed multilevel samplers

Inverse modeling for locating dense nonaqueous pools in groundwater under steady flow conditions

“…Perhaps the most promising of these is to flush chemical additives through impacted media in order to dissolve and/or mobilize entrapped NAPL. Among these additives are organic cosolvents [Imhoff et al, 1995;Sillan et al, 1998] and surfactants [Abriola et al, 1993]. Successful application of these technologies requires adequate knowledge of the DNAPL location in the subsurface.…”

Lab Testing and Field Implementation of Soil Flushing

“…The maximum efficiency of a cosolvent is a function of the solubilization or cosolvency power ) of the cosolvent, while the hydrodynamic efficiency achieved depends on the hydrogeologic heterogeneities of the aquifer (e.g., spatial correlation structure if the hydraulic conductivity); the composition and properties of the NAPL (e.g., singleor multi-component; density; wettability), and the fluid properties (e.g., viscosity, density and NAPL-water interfacial tension) of the solvent mixture used for flushing. Low-molecular-weight n-alcohols (e.g., methanol, ethanol, tert-butanol, pentanol, and hexanol) have been used as cosolvents Sillan et al 1998). Ethanol flushing was shown to be effective in solubilizing >85% of several target contaminants from an light NAPL (LNAPL) source zone at Hill AFB, UT , and about 60% of PCE from a source zone at a drycleaner site in Florida .…”

“…Low-molecular-weight n-alcohols (e.g., methanol, ethanol, tert-butanol, pentanol, and hexanol) have been used as cosolvents Sillan et al, 1998b). Ethanol flushing was shown to be effective in solubilizing >85% of several target contaminants from an light NAPL (LNAPL) source zone at Hill AFB, UT , and about 60% of PCE from a source zone at a drycleaner site in Florida .…”

“…Field studies at Hill AFB, UT and in Jacksonville, FL (Sillan et al, 1998; conducted in-situ flushing with food-grade ethanol, because of concerns with additives or "contaminants" in non-food-grade ethanol. Generally, for similar reasons, food-grade surfactants are preferred for in-situ flushing.…”

Horizontal ethanol floods in clean, uniform, and layered sand packs under confined conditions

“…The cosolvents are typically short-chain aliphatic organic compounds such as methanol, ethanol, propanol, acetone, methyl ethyl ketone, etc. [Grubb and Sitar, 1994; Rao et al, 1997; Jawitz et al, 1998;Sillan et al, 1998]. More broadly, the stability of flooding fronts is paramount to efficiently displacing the resident pore fluids from a variety of porous media: oil reservoirs, filter beds, fixed beds (regeneration), and aquifer media [Homsy, 1987].…”