1. Professor, School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (corresponding author).
2. Battelle Memorial Institute, 397 Washington St., Duxbury, MA 02332.
3. Massachusetts Water Resources Authority, Charlestown Navy Yard, 100 First Ave., Boston, MA 02129.
4. Principal Engineer, Hazen and Sawyer, 498 Seventh Ave., New York, NY 10018.