Design and Construction of Kaumalapau Harbor Breakwater Island of Lanai, Hawaii

Kaumalapau Harbor is a small barge harbor located on the southwest coast of the island of Lanai in the State of Hawaii, U.S.A. The harbor was protected by an old, deteriorated, rock rubblemound breakwater, originally constructed in 1925. The breakwater was recently completely rebuilt by the U.S. Army Corps of Engineers, Honolulu District, in association with the State of Hawaii. Oceanographic design considerations included a water depth of about 21 m (70 ft) and direct exposure to possible 10.7 m (35 ft) hurricane strength storm waves. The repairs utilized an armor layer of 31.8 tonne (35 ton) Core-Loc^TM concrete armor units, the largest units of this type used to-date. The use of Core-Loc units, a relatively new armor unit type, presented both design and construction challenges to insure that their performance capability was maximized. Particular attention was placed on developing a Core-Loc placement plan to achieve the required unit packing density, and utilizing rigorous construction techniques to achieve the specified armor layer placement. This project contributed significantly toward furthering design and construction guidelines for Core-Loc use. Construction was completed in 2007, and the project won the ASCE, Hawaii Section, 2008 Outstanding Civil Engineering Achievement Award.