ACER Technical Memorandum No. 2 - Freeboard criteria and guidelines for computing freeboard allowances for storage dams

Revision of the 1981 document.

This document presents Bureau of Reclamation policy pertaining to freeboard allowances for storage dams. Freeboard is provided to prevent overtopping of the dam crest by waves. Freeboard also provides an additional measure of safety of the dam to account for the uncertainties in accurately estimating reservoir water surfaces and wave heights, and uncertainties in reservoir operation and structure performance. This memorandum contains information on the many considerations that are required for freeboard analysis as well as methods to account for these considerations and perform the analysis. This edition...is significantly different from the original 1981 edition. This second edition offers a simplified approach to freeboard calculations under certain conditions and suggests a probabilistic approach if the simplified computations are not appropriate. More extensive wind data are also now available to facilitate the use of probability. The wind effects on water have also been revised according to the latest Corps of Engineer’s studies. The crest elevations of both new and existing dams may be evaluated on the basis of a calculated risk.