Pillar Point Harbor
Half Moon Bay, CA
A breakwater system was designed for development of an extensive recreational and commercial fishing boat berthing facility located within a semi-protected Federal harbor of refuge on the open coast. Alternative methods were studied to provide shelter from deep water storm swell transmitted through existing and permeable rubble-mound structures, and short period seas locally generated within a broad inner harbor fetch. A matrix of breakwater cross-sections and layouts was formulated and analyzed to select an optimum plan that achieved the desired level of wave attenuation; minimized adverse wave reflection at the specially configured entrance; satisfied navigation maneuvering and visibility requirements; and maintained acceptable water circulation via natural tidal flushing processes. Physical hydraulic model tests were conducted in a small-scale ripple tank to economically assess the merits of the 49 alternative plans that were considered. The preferred plan consisted of over 3,300 feet of rubble-mound breakwater, including a 1,200-foot detached offshore segment. NCI provided the various oceanographical wave and current studies to specify the project’s design criteria; prepared the detailed structural design of the preferred plan; evaluated and approved potential quarry stone sources for the multi-layered cross-section; and provided construction inspection and consultation services.