1. Sanitary Engineer, Wastewater Enterprise, San Francisco Public Utilities Commission, City and County of San Francisco, San Francisco, CA 84124 (corresponding author).formerly, Graduate Research Assistant, Dept. of Civil Engineering, Univ. of Alberta, Edmonton AB, Canada T6E 5L9.
2. Professor, Dept. of Civil Engineering, Univ. of Alberta, Edmonton AB, Canada T6G 2W2.