Louis Theodore, Eng.Sc.D, (retired) was a Professor of Chemical Engineering for 50 years. He is the author of several publications, including Fluid Flow for the Practicing Chemical Engineer, Thermodynamics for the Practicing Engineer, Mass Transfer Operations for the Practicing Engineer, and Air Pollution Control Equipment Calculations and Pollution Prevention. R. Ryan Dupont, PhD, is Cazier Professor of Civil and Environmental Engineering, and a Research Associate at the Utah Water Research Laboratory. He is the author of many research publications and books including Groundwater and Soil Remediation: Process Design and Cost Estimating of Proven Technologies, Water Resource Management Issues: Basic Principles and Applications, and Unit Operations in Environmental Engineering.