ENGINEERING RESILIENCE
The Glass Breakwater project ... represents an effor to transition from a reactive maintenance cycle to a compre- hensive, engineered strategy for long-term resilience.
site characterization, numerical wave modelling, physical model testing, advanced armor unit placement tech- nology and real-time wave forecasting. It also recognizes the unique condi- tions of Guam — from its steep off- shore shelf and coral reef environment to its exposure to powerful and pro- longed typhoons. The TPC-NAN JV project team is working with environmental agencies and following required procedures, including measures related to coral spawning. Construction is expected to take approximately four years. Work will continue through challenging weather periods, with wave forecasting helping the team determine when conditions are suitable for specific activities. For a structure that has protected Guam for more than eight decades, the goal is straightforward: ensure it can continue to do so. “The Glass Breakwater has protected Guam for over 80 years,” Treflik-Body told APP conference delegates. “Storms like Sinlaku and Bavi have reminded us how critical it remains today.” By combining lessons from the structure’s long history with modern engineering, physical modelling and real-time data, the project is creat- ing a new chapter in the life of one of Guam’s most important pieces of mar- ine infrastructure. For Apra Harbor, the stakes extend well beyond the breakwater itself. Its continued performance supports safe commercial port operations, protects critical infrastructure and contributes to naval readiness. The new Accropode TM armor sys- tem is designed to provide the stabil- ity needed to withstand Guam’s severe wave climate — helping ensure that the Glass Breakwater remains a first line of defense for the island’s mari- time economy and security for dec- ades to come.
foundation for the first Accropode TM units. The working platform is subse- quently backfilled and the existing sea- ward face of the structure is reshaped to create the sloping stone under- layer. Finally, the Accropode TM units are installed to achieve a pre-defined placement grid and varying unit orien- tations as per technical guidance pro- vided by Concrete Layer Innovations (CLI), the licensor for the Accropode TM technology. Accurate placement is achieved using a crane equipped with the POSIBLOC TM placement system. This system provides real-time place- ment coordinates and orientation for each unit as it is placed, and provides the crane operator with a digitally-gen- erated image of the previously placed units to assist in the final placement of each unit to meet the specified requirements. Using real-time data to manage construction risk Real-time wave forecasting has been integrated into the construction plan- ning process. A wave buoy positioned just offshore of the breakwater feeds measured information into a wave fore- cast model, with this model producing daily reports that identify conditions suitable for construction activities. The system provides the construction team with a forward-looking view of when in-water activities can safely and effect- ively proceed. For a project operating in one of the Pacific’s most challenging storm environments, reliable wave forecast information is critical. The importance of this approach was demonstrated by two recent Super Typhoons (Sinlaku and Bavi), with the forecast output
guiding the contractor in preparing for the storms, including “buttoning up” work in progress to the extent possible and implementing protection meas- ures for large construction equipment that could not be removed from the breakwater. At the time of Super Typhoon Sinlaku (mid-April), no Accropode TM units had been installed on the struc- ture. The project team was preparing the underlayer when the storm caused significant erosion and material loss along the breakwater, requiring emer- gency repairs before permanent con- struction could resume. The first Accropode TM units were placed in late May. In early July, Super Typhoon Bavi provided another real- world test of the developing repair. Approximately 400 feet of Accropode TM units had been installed when the storm struck. Treflik-Body noted that the repaired section sustained no sig- nificant damage, although other por- tions of the existing breakwater did require additional emergency repairs. The experience gained during these two storms clearly demonstrated the fragility of the existing breakwater and provided an important early indication that the repair design was performing as intended. Building for the next generation The Glass Breakwater project is more than a major infrastructure rebuild. It represents an effort to transition from a reactive maintenance cycle to a com- prehensive, engineered strategy for long-term resilience. For decades, the structure was maintained through a series of tar- geted repairs following storm damage. The new approach combines detailed
42 — PACIFIC PORTS — October 2026
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