1. Asst. Prof. of Civ. Engrg., Zagazig University—Shobra Branch, Cairo, Egypt.
2. Prof. of Civ. Engrg., Univ. of Illinois, 205 N. Mathews Ave., Urbana, IL 61801.
3. Envir. Engr., Central Ofc., Div. of Solid and Infectious Waste Mgmt., Ohio Envir. Protection Agency, Columbus, OH.
4. Civ. Engr., Schaeffer, Amos, & Hughes, LLC, 1253-G Lyons Rd., Dayton, OH 45458; formerly, Envir. Engr., Southwest District, Div. of Solid and Infectious Waste Mgmt., Ohio Envir. Protection Agency, Dayton, OH.