1. Associate Member, ASCE
2. Member, ASCE
3. Sr. Geoenvir. Engr., Tonkin and Taylor Ltd., Newmarket, Auckland, New Zealand. E-mail: mkhire@tonkin.co.nz
4. Prof., Dept. of Civ. and Envir. Engrg., Univ. of Wisconsin, Madison, WI 53706. E-mail: chbenson@facstaff.wisc.edu