1. Prof. of Civ. Engrg., Univ. of Illinois, 205 N. Mathews Ave., Urbana, IL 61801.
2. Asst. Prof. of Civ. Engrg., Zagazig Univ.—Shobra Branch, Cairo, Egypt.
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 Dist., Div. of Solid and Infectious Waste Mgmt., Ohio Envir. Protection Agency, Dayton, OH.