Work involved the bathymetric survey, site reconnaissance, coastal engineering analysis, engineering design, opinion of construction cost, and the preparation of construction drawings and specifications for the replacement of the deteriorated timber breakwater with a concrete structure. The design consisted of precast concrete panels and batter piles and a cast-in-place concrete deck and cap. Half of the structure provides fishing and public access. Special details were included in the design to enhance water circulation and encourage native oyster colonization. A design challenge consisted of specifying sheet pile and batter pile lengths for the highly variable foundation soil profile.

The work also included design for replacement of a windsurfing launch ramp. NCI performed construction engineering and resident inspection during the construction.

Preliminary engineering and design studies were performed by NCI to improve the existing Federal structure. A 100-foot rubble-mound spur was designed using hydraulic model test parameters to remedy localized beach erosion. The design included void sealing of the groin’s core to reduce upcoast sand leakage, and rebuilding of a portion of the groin’s mid-section to repair structural deficiencies. NCI prepared the detailed design plans and construction documents, supported the permit application process, and furnished on-site construction consultation.

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.