1. Consultant, Bengt Fellenius Consultants Inc., 1905 Alexander St. SE, Calgary, AB Canada T2G4J3. E-mail: bengt@fellenius.net
2. Senior Geotechnical Engineer, Berkel and Company Contractors Inc., 1808 Northshore Hills Blvd., Knoxville, TN 37922 (corresponding author). E-mail: tcsiegel@knology.net