Design for Small-Boat Harbor Improvements and Tidal Flushing, St. Paul Harbor, St. Paul Island, Alaska

A 1:10-scale (undistorted) three-dimensional coastal hydraulic model was initially used to investigate the design of proposed harbor improvements at St. Paul Harbor, St. Paul Island, Alaska, with respect to wave and current conditions in the harbor and sediment patterns at the site. Wave-induced circulation and sediment patterns seaward of the main breakwater as a result of submerged reefs were investigated. Proposed improvements consisted of deepening the entrance channel, constructing a maneuvering area and installing a wave dissipating landfill inside the existing harbor, and constructing submerged reels seaward of the main breakwater. The model was reactivated in 1997 to study, on a preliminary basis, small-boat harbor improvements and flushing of Salt Lagoon in St Paul Harbor. In this study, the model was reactivated to finalize the design of small-boat harbor improvements and flushing at St. Paul Harbor. The model reproduced approximately 2,865 m (9,400 ft) of the St Paul shoreline, the existing harbor, the surface area of Salt Lagoon with its connecting channel to the harbor, and sufficient offshore area in the Bering Sea to permit generation of the required test waves. An 18.3-m-long (60-ft-long) unidirectional, spectral wave generator and an automated data acquisition and control system were used in model operation. Conclusions from study results were as follows: (a) Preliminary experiments indicated that all improvement plans would result in wave heights of less than 0.3 m (1.0-ft) in the small-boat mooring area for short-period storm wave conditions. (b) Preliminary experiments indicated that the harbor would experience long-period (surge) conditions for all the improvement plans.