1. Research Director, Water Treatment Research, Inc., 2291 Plantation Ct., Lawrenceville, GA 30044. E-mail: james_amburgey@engineer.com
2. Professor Emeritus, Dept. of Civil and Environmental Engineering, Georgia Tech, Atlanta, GA 30332; and Senior Consultant/Principal Technologist, CH2M Hill, Sacramento, CA 95833. E-mail: appiah.amirtharajah@ch2m.com