Labyrinth Spillways

State dam safety program responses to the following inquiry: Due to the expressed interest from the dams community regarding nappe vibration and debris, we have prepared the following brief survey. The intent is to provide new and useful information and applied research to owners, regulators, and practitioners regarding labyrinth spillways. We also seek to develop a more complete list of labyrinths built in the USA. This information will be compiled and presented in several upcoming technical papers and presentations at national and international conferences focused on dams. We greatly appreciate you taking the time to complete this survey.

1. How many labyrinth spillways are in your state? Please list structure names.
2. Do any of these spillways exhibit nappe vibration (pulsating acoustic pressure waves)?
3. Does debris accumulate at any labyrinths in your state when not spilling ? If so, please describe type of debris and if this is a concern.
4. In general, how do your labyrinth spillway s handle floating debris? Are they self-cleaning (i.e., debris passes over the spillway during storms, etc.)?
5. Are there any issues such as blockages, log jams, required post - storm maintenance, etc.? If so, please elaborate.
6. Has the labyrinth improved debris and related maintenance issues that existed prior to its construction? Have any new issues developed because of the labyrinth?
7. Were potential debris issues considered during design? Or, how have you mitigated debris issues since construction?

The ASDSO surveys archive is available to members through the members only section of DamSafety.org