Hawaiian Environment Offers Unique Benefits in DoD Corrosion Battle
By Brett Ingold
The DoD and Army facilities located at Kawaihae Harbor, on Hawaii’s Big Island, are nestled in a beautiful, scenic location. The harbor offers a unique environment for developing new technologies that can help win the fight against corrosion.
Kawaihae Harbor plays host to the U.S. Army Garrison-Hawaii, which includes the Pohakuloa Training Area along with major DoD port facilities. The harbor is a busy thoroughfare that handles significant traffic every day.
One of the key pieces of infrastructure critical to daily operations is a manmade concrete structure commonly referred to as a “dolphin.” The dolphins, located within the harbor, are used to guide sea-bearing vessels for the Army and Navy. The Army is leading an effort designed to extend the service life of the dolphins by minimizing corrosion and concrete spalling caused by unique Hawaiian water conditions.
 |
Concrete dolphin structures sit offshore in Kawaihae Harbor, Hawaii. |
The long-term goal of this effort is to provide economically feasible options to extend the useful (service) life of concrete infrastructure pilings, the primary support pilings for dolphins and other marine structures used by the military worldwide.
Hawaii’s Environmental Challenges—A Boon for Researchers
Hawaii offers marine, land, and volcanic testing environments along with exposure to a variety of environmental factors like sunlight, wind, rain, and sand. While the Hawaiian environment offers many benefits to the DoD and other agencies, it also presents a number of additional challenges along the way. Many research projects are conducted on the Hawaiian Islands because of the ability to find a wide variety of environments within a small radius.
In this effort, the Hawaiian water environment is of primary interest. These waters offer high concentrations of oxygen to sustain marine life. However, the water also has an extremely high salt concentration, the main contributor to the concrete spalling problem observed on the dolphin structures. If this problem is left untreated, the critical functions of Kawaihae Harbor could be drastically affected.
Led by Corps of Engineers, DoD Partners Address a Corrosion Problem
The dolphins are supported by concrete, steel-reinforced pilings. These structural components are highly susceptible to this harsh environment. The environment’s high concentrations of salt rapidly attacks manmade structures and leads to rapid erosion and corrosion of their structural components. The dolphins corrode through a process known as rapid spalling of concrete.
In order to find a way to extend the service life of these critical structures, the DoD Office of Corrosion Policy and Oversight, the Assistant Chief of Staff for Installation Management, and the Installation Management Command have initiated a jointly sponsored study at Kawaihae Harbor. The partners involved in this effort include the U.S. Army Garrison-Hawaii, the Pohakuloa Training Area, Naval Facilities Engineering Command, and the Army Corps of Engineers, Engineer Research and Development Center’s Construction Engineering Research Laboratory (ERDC-CERL). (The Pacific Ocean Division and Hawaii District of ERDC-CERL are specifically involved.)
 |
| A dive crew installs composite wrapping on a concrete piling attached to a “dolphin.” |
ERDC-CERL’s research has centered on three dolphin structures within the harbor. The first of these structures was installed around 1980, and is nearing the end of its planned service life. The other two dolphin structures are newer, installed in the early 2000s, and will be protected with a composite wrapping and galvanic protection system.
The effort of minimizing the effects of salt on these concrete pilings is being led by ERDC-CERL within Kawaihae Harbor and is the Army’s first such effort. The goal is to install and test a composite wrap integrated with a cathodic protection (CP) system to prevent corrosion and provide protection from impact damage within the splash zone region of the reinforced concrete piles of the two newer dolphin structures. The older third piling will not be wrapped, but will instead serve as a reference point.
“The long-range goal of this effort is to provide design guidance for future use of this wrapping at other installations and on other types of marine infrastructure exposed to harsh environments,” said Dave Bailey, the project manager at ERDC-CERL.
Wrapping the Dolphins
The wrapping of dolphin structures within Kawaihae Harbor was completed using a dive crew and a CP team. “The two newer dolphins are located 75 to 100 feet from the shore and posed unique challenges for the dive crew, as far as access to the structures. The logistics were well handled by the CP team, which used scaffolding that could float under the dolphins where the water was over 15-feet deep,” Bailey said.
Instrumentation was placed on the wrapped piles to determine the corrosion potential of the reinforcement steel. The data collection system is powered by photovoltaics, the application of solar cells for energy, achieved by converting sunlight directly into electricity. The system uploads daily results of the corrosion study via satellite to computers located at ERDC-CERL in Champaign, Illinois. The data will also be accessible to Hawaii garrison field engineers on a Web site and will be made available to the public once the data collection is finished.
The data collection is ongoing and will illustrate any possible benefits in service life extension. “Corrosion potential measurements are used to indicate the effectiveness of the wrapping in preventing further corrosion, and will continue for four years,” Bailey said.
Corrosion is generally an expensive problem regardless of the area it affects. It currently costs more than $100 million annually to address corrosion issues on U.S. military piers worldwide. The potential benefits of this effort are of great interest to the entire maintenance community.
|
