Project Name: BHP Billiton Mitsubishi Alliance

Asset Description

The Hay point coal terminal is used to export coal mined near Mackay, Queensland the terminal consists of twin berths known as berth 1 and berth 2. The structure consisted of individual caisson manufactured and floated into position before submerged into place and creating the berthing terminal. 

The structures are used to facilitate the docking of large ships offshore to secure for loading purposes.

The coal terminal structures are an integral asset to facilitate loading requirement and berthing facilities. The structures are prone to some of the worst conditions in the world, this includes tidal, humidity and a cyclone prone area within a marine environment. The concrete structures are suffering from steel reinforcement corrosion due to exposure to high concentrations of chloride and moisture at elevated temperatures.

Concrete spalling and corroded reinforcement was observed in the initial condition assessment.

Infracorr Consulting was appointed by the client to perform a diagnostic assessment of the concrete elements for the purpose of identifying the current condition of the concrete and providing options for rehabilitation and long-term protection of the asset.

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Solution

The Duoguard Hybrid Anode corrosion control treatment was chosen in preference to an impressed current system.  Both the Hybrid and galvanic systems were considered, however due to the environment and condition of the structure the Hybrid Cathodic treatments was evaluated as the most cost-effective option.  

Queensland complete contracting services [QCCS] was awarded the project, access to each caisson was via fixed scaffold to complete the corrosion control treatments. The site posed some difficult situations by being exposed to the elements and tidal influences experienced in the area including shipping movements. 

Infracorr consulting closely monitored and provided site supervision during the rehabilitation stages, this project is estimated to be completed in 2020.

The Benefits

The Duoguard hybrid cathodic protection system was installed to ensure similar performance equivalent to traditional ICCP systems however with lower installation and ongoing costs. The hybrid system was chosen as the most practical corrosion treatment system, only loose or delaminated concrete was removed.  

Monitoring has been designed to allow regular and cost-effective remote monitoring of the systems performance from anywhere where there is Internet access. 

Monitoring thus far indicates that the Hybrid system is protecting the reinforcement as the design had intended.