Three-fluid retention in porous media involving water, PCE and air

A review of non-invasive imaging methods and applications in contaminant hydrogeology research

“…An important first use of gamma radiation imaging for contaminant hydrogeology research was to generate fluid saturations (Ferguson and Gardner, 1962; Fritton, 1969), in some cases to compute parameter values for saturation-pressure relations (Ferrand et al, 1986; Dane et al, 1992; Hofstee et al, 1997; White et al, 2004). Measurements with gamma radiation assure the determination of such curves locally within a porous medium, rather than providing data averaged over the total volume of a relatively large sample, as determined with typical pressure cells.…”

“…For example, Dane et al (1992) showed that a gamma radiation system could be used to determine both water and DNAPL trichloroethene (TCE) saturations every 1 cm along a 1-m-long column; this coupled with fluid pressure distributions at hydraulic equilibrium were used to develop saturation-pressure relationships. Hofstee et al (1997) used a similar approach to measure water and DNAPL perchloroethene (PCE) saturations at eight different locations along a 1-m-long column. These measurements were used to investigate the nonspreading behavior of the PCE in unsaturated conditions.…”

Final Technical Report EMSP 70045 Investigation of Pore Scale Processes That Affect Soil Vapor Extraction

“…This is illustrated below in Figure 7. Hofstee et al (1997) measured capillary-pressure saturation curves for a nonspreading NAPL (tetrachloroethene) in a three-phase (air-water-NAPL) system. Above residual saturation, applied suction was required to displace the NAPL with air, indicating that capillary forces held the NAPL in place above residual saturation, and that gradients in capillary pressure could potentially cause flow.…”

Volatilization of Non-Aqueous Phase Liquid in Porous Media: Vapor Phase Mass Transfer Characteristics

“…For the measurement of pore structure for pairs of wetting and nonwetting fluids, generally hydrologists and soil scientists use the capillary pressure-saturation (Pa-,S) relationships that reflect the pore structure characteristics of the medium (Lenhard and Parker, 1987;Ferrand et al, 1989;Hofstee et al, 1997). When a nonwetting fluid, such as NAPL or gas invades water, or gas displaces NAPL, the process is called drainage.…”