ICRI 2009 Project Award Winner
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Award of Excellence: Water Structures Category

Kawaihae Harbor Mooring Structure Cathodic Protection
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Kawaihae Harbor, Hawaii

Submitted by Electro Tech CP


Kawaihae Harbor Mooring Structure

Owner
U.S. Army Corps of Engineers
Champaign, Illinois

Project Engineer/
Designer

U.S. Army Corps of Engineers
Champaign, Illinois

Repair Contractor
Electro Tech CP
Tequesta, Florida

The U.S. Military facility at Kawaihae Harbor, HI, serves 
as the main port for delivery of equipment used at the Pohakuloa Training Area. Ships arrive at the facilities’ mooring dolphins, built in 2001. They consist of two dolphin structures and a concrete ramp. Dolphin No. 2 is a concrete platform supported by 21 prestressed, octagonal concrete piles, and Dolphin No. 3 is supported by 19 prestressed, octagonal concrete piles. The piles are driven directly into the bottom of the sea floor. 

The owner and engineer had conducted several inspections of the dock and piers. They discovered that the piles had cracks in the concrete, allowing ingress of seawater, causing the prestressing steel to corrode. The owner wanted a repair system that would provide corrosion protection to the concrete piers. The system, however, had to be durable so it would not be easily damaged by impact from large ships or floating debris. 

The project team opted to use a sacrificial cathodic protection system. The galvanic system establishes a current flow from an externally placed anode to the steel reinforcement. This current flow provides enough energy to polarize the steel reinforcement. The polarization overcomes the isolated anodic and cathodic sites (local corrosion cells) on the reinforcement, thus creating an electrically homogeneous cathodic condition for the steel in relation to the newly placed anode. Under the newly created conditions, the steel ceases to corrode while the external anode does instead. A compression panel made of a wood/plastic composite material also was used for each face of the piles to secure the expanded zinc mesh anode sheet to the concrete surface. 

Although the remote location of this project required tremendous planning, the repair strategy was a huge success. The team faced many challenges, including tidal conditions, inclement weather, and continuous operation of the mooring dolphin structures during installation. The installation of a remote monitoring system solution will provide the owner with valuable data on system performance.

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