1. Staff Engineer, Brown and Caldwell Environmental Engineers and Consultants, 333 E. Wetmore Road, Suite 165, Tucson AZ 85705 (corresponding author).
2. Affiliate Professor, Dept. of Civil and Environmental Engineering, Univ. of Washington, P.O. Box 352700, Seattle, WA 98195 and Senior Geologist, Stillwater Sciences, 1314 NE 43rd St., Seattle, WA 98105.
3. Professor, Dept. of Civil and Environmental Engineering and Public Affairs, Univ. of Washington, P.O. Box 352700, Seattle, WA 98195.