1. Department of Civil and Environmental Engineering, Texas Tech University, Lubbock, Texas 79409-1023, The Institute of Environmental and Human Health, Department of Environmental Toxicology, Texas Tech University, Lubbock, Texas 79409-1163, Freese and Nichols, Inc., 2220 San Jacinto Boulevard, St 330, Denton, Texas 76205, and Department of Civil and Environmental Engineering, Texas Tech University, Lubbock, Texas 79409-1023