Dr. Rex Bryan has a Ph.D. in Mineral Economics/Geostatistics from the Colorado School of Mines, and a MS in Geology from Brown University. Dr. Bryan has specialized in environmental statistics and modeling with more than 25 years of experience, including 18 years of experience in hydrogeology, site assessment, risk assessment, and remediation. He has been a co-author of several of EPA guidance documents including: Guidance for Data Usability in Risk Assessment (USEPA, April 1992, 9285.7-09A) Dr. Bryan has statistically analyzed soil and groundwater contaminated by petroleum, gasoline, diesel, PAHs, dioxins, and chlorinated chemicals. He has programmed geostatistical software to model groundwater flow down- gradient, with lateral dispersion using gaussian diffusion concepts, and is currently performing geostatistical analysis of ground water contamination from the Colorado Department of Transportation Materials Testing Laboratory. Dr. Bryan has evaluated direct push and ground penetrating radar technologies for the EPA Office of Technology Assessment (TIO) and used state-of-the-art ground water modeling programs, including MEPAS, to model the movement of chemicals from spills within several media simultaneously. MEPAS can be requested to convert all concentrations into human risk values. He has characterized rate, concentration, and extent of horizontal and vertical migration of contamination in ground water for numerous sites. He has worked on environmental projects in Louisiana, Texas, and Mississippi, and many other states, as well as sites outside the United States.