Inadequate spillway capacity, significant hydrologic loadings on embankments and structures, and operation and maintenance are common dam safety issues, instigating the need for risk-reduction measures and/or rehabilitation. 3D weirs, or weirs with a crest length greater than the spillway width, are a particularly efficient approach to reduce these concerns. These weirs are also commonly used in new dams and may be useful as levee spillways. In some cases, these structures may be an alternative to gated spillways, which require operation and maintenance and can cause downstream flooding from misoperation or failure. Examples of 3D weirs include: arced or curved weirs, box-inlet drop spillways, labyrinth and piano-key weirs, and labyrinth fuse gates. Because of their hydraulic performance and site-adaptive geometries, these types of weirs are of increasing interest to those involved in dam safety, including practitioners, researchers, regulators, and dam owners. However, these spillways have complex hydraulic behaviors and can be challenging to develop efficient designs.
Brian Crookston, Ph.D., P.E.
Schnabel Engineering/Senior Engineer
Brian Crookston, PhD, PE is a Senior Engineer and Water Resources Technical Discipline Coordinator with Schnabel. His primary role is as an H&H technical resource for dam and levee projects company-wide. He has particular interests in water conveyance, hydraulic structures, and dam safety, including spillway hydraulics, flow acoustics, debris, energy dissipation, physical and numerical modeling, and design optimization.
Greg Paxson, P.E.
Greg Paxson, PE is a Principal with Schnabel and manages the dam engineering group in the West Chester, Pennsylvania office. Greg received his undergraduate degree in Civil Engineering from the University of Delaware and his Master's degree from Villanova University. He is registered as a Professional Engineer in eight states and has 20 years of experience in dam engineering. He has been involved in the design of nearly 50 dam rehabilitation projects, including numerous spillway upgrades and more than 20 projects involving labyrinth spillways.