This research, funded through U.S. Department of Energy's Idaho National Engineering and Environmental Laboratory's Subsurface Science Initiative (SSI), supports the DOE's mission in environmental science.
Hydrologist Robert Lenhard of the INEEL, has resolved a critical contamination modeling problem by refining current constitutive theory - theory describing relations among fluid relative permeabilities, saturations, and pressures. His new model predicts the distribution of residual NAPL based on the prior fluid wetting and drying cycles in the subsurface. Lenhard will present his work at the American Geophysical Union meeting in San Francisco, CA, on December 8, 2002 during the Hydrology session.
"If you run existing multiphase flow models long enough, the results show that NAPL will completely drain from a vadose zone, which is contrary to field and experimental observations" said Lenhard. Better constitutive theory is needed for developing accurate computer models. "The lack of well-founded constitutive theory may be the foremost element impeding the development of accurate predictive multiphase flow models," he adds.
Lenhard's modeling advance represents a shift in researchers' conceptual understanding of NAPL behavior by recognizing that some NAPL becomes immobilized in pore spaces
Contact: Deborah Hill
DOE/Idaho National Laboratory