Abstract
Steel sheetpile bulkheads installed in the late 1940's and early 1950's at a U.S. Government facility on a Pacific island in the western Hawaiian chain have experienced severe localized corrosion failures due to exposure to sea water. The bulkheads were installed without any corrosion control measures (no coatings or cathodic protection) and are now in need of replacement. The purpose of the bulkheads is primarily to eliminate the natural erosion of the island's shoreline but in one location they are used to form a protected harbor. Virtually the entire island is ringed with sheetpiling, but the only locations presently being rehabilitated are those considered to be at especially critical locations -- the airstrip, harbor entrance, tank farm and dock areas.
A corrosion survey was conducted to investigate the potential for external corrosion on the replacement steel sheetpile bulkheads and to collect data necessary for the selection and design of appropriate cathodic protection systems. The survey included measuring the soil resistivity and pH on both the island and ocean sides of the existing bulkheads.
The survey revealed that cathodic protection was necessary only on the ocean side of the replacement bulkheads. Galvanic cathodic protection utilizing aluminum anodes was designed for the ocean side of the bulkheads; this type of system is easier to install and maintain and has a lower total life cycle cost than impressed current cathodic protection.
