1. Civil Engineer, DNV GL, 1601 Rio Grande St., Suite 400, Austin, TX 78701 (corresponding author).
2. Frank H. Neff Professor, Dept. of Civil Engineering, Case Western Reserve Univ., Cleveland, OH 44106.
3. Retired, P.G. Geologist, Appalachian Regional Office of the US Office of Surface Mining Reclamation and Enforcement, 3 Parkway Center, Pittsburgh, PA 15220.