Newell

TODD H. WIEDEMEIER, PG, is a technical director at Parsons Engineering Science, Inc., in Denver, Colorado.

HANADI S. RIFAI, PhD, is an assistant professor in the Department of Civil and Environmental Engineering at the University of Houston, Texas.

CHARLES J. NEWELL, PhD, PE, is Vice President and Environmental Engineer at Groundwater Services, Inc., in Houston, Texas.

JOHN T. WILSON, PhD, is a senior research microbiologist.