1. Asst. Prof., Environmental Engrg. Dept., Cornell Univ., Ithaca, N.Y. 14853
2. Civ. Engrg. Dept., Stanford Univ., Stanford, Calif. 94305
3. Engr., Culp, Wesner, and Culp Consulting Engrg., P.O. Box 518, Cameron Park, Calif. 95682
4. Chmn. and Prof., Civ. Engrg. Dept., Stanford Univ., Stanford, Calif. 94305