HR: 09:00h
AN: H21H-05    [Abstracts]
TI: Effects of Temperature on Immiscible Displacement of a Viscous NAPL
AU: * O'Carroll, D M
EM: docarroll@eng.uwo.ca
AF: Department Civil and Environmental Engineering, The University of Western Ontario, Spencer Engineering Building, London, ON N6A 5B9 Canada
AU: Sleep, B E
EM: sleep@ecf.utoronto.ca
AF: Department of Civil Engineering University of Toronto , 35 St. George St., Toronto, ON M5S 1A4 Canada
AB: Thermal remediation techniques, such as hot water flooding, are emerging technologies that have been proposed to remove significant amounts of nonaqueous phase liquids (NAPLs) from the subsurface. These techniques were originally developed in the petroleum industry for enhanced petroleum recovery and later adapted for the remediation of NAPL contaminated sites. Hot water flooding exploits the temperature dependence of fluid properties, such as viscosity and interfacial tension, to improve NAPL removal efficiencies. Improved NAPL removal efficiencies result in reduced source longevity. Although hot water flooding has been applied at various remediation field sites it has received relatively little laboratory study in the contaminant hydrology community. This presentation describes results of a laboratory and modeling investigation designed to determine if hot water flooding techniques improve NAPL mass removal when compared to ambient temperature water flushing. Experiments were conducted in a bench scale two-dimensional sandbox (55 cm by 45 cm by 1.3 cm) and NAPL saturations were quantified using a light transmission apparatus in conjunction with a 14 bit CCD camera (1536 x 1024 pixels).Two immiscible displacement experiments were conducted in which the aqueous phase displaced a NAPL saturated zone. In the first experiment fluids were at ambient temperature (22 oC) and in the second fluid temperatures were elevated to approximately 50 oC. The hydraulic properties of the selected LNAPL, Voltesso 35, are strongly temperature dependent. At 50 oC Voltesso35 viscosity is 30 % of its value at ambient temperatures and the aqueous phase/Voltesso 35 interfacial tension is 83 % of its value at ambient temperatures. Experimental results of both the cold and hot water flooding experiments will be presented. A numerical simulator has been modified to include simultaneous flow of water and organic phases, energy transport, temperature and pressure. Model predictions of mass removal and NAPL saturation profiles compare well with observed behavior. A sensitivity analysis will be presented, exploring the temperature dependency of NAPL hydraulic properties, to assess the conditions under which it is advantageous to employ hot water flooding techniques.
DE: 1800 HYDROLOGY
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1847 Modeling
DE: 1849 Numerical approximations and analysis
SC: Hydrology [H]
MN: Fall Meeting 2005