CONFERENCE RECAP: ENGINEERING RESILIENCE
Engineering Resilience Rebuilding Guam’s Glass Breakwater
F or more than 80 years, Guam’s Glass Breakwater has stood as a critical line of defense for Apra Harbor, protecting the port’s economic activity and supporting the operational readiness of U.S. naval facilities. But decades of typhoons, wave action and successive repairs have taken their toll on the massive structure. Erica Treflik-Body of W.F. Baird & Associates Ltd. (Baird) offered delegates of the APP’s conference an inside look at the history, engineer- ing challenges and innovative repair strategy now being implemented to strengthen the breakwater for decades to come. Baird is part of the TPC-NAN JV and is the coastal engineering firm responsible for the design of the repair project, which forms part of the $571 million Apra Harbor Waterfront Repair (AHWR) Project being under- taken by Naval Facilities Engineering Systems Command (NAVFAC). “The Glass Breakwater is Apra Harbor’s first line of defense,” Treflik- Body said. “For port operations, it reduces wave energy, allowing cargo ships to berth safely, cranes to oper- ate reliably, and goods to move with- out costly delays.” She added that its importance extends beyond com- mercial activity. The breakwater also protects naval berths, fueling sta- tions and other critical infrastructure from Guam’s typhoon-driven seas. “In short, this breakwater safeguards Guam’s economic engine and its mari- time security,” she said. A structure built for another era The Glass Breakwater is named after U.S. Navy Admiral Henry Glass, who played a significant role in Pacific operations in the late 19th century.
“The Glass Breakwater is Apra Harbor’s first line of defense ... In short, this breakwater safeguards Guam’s economic engine and its maritime security,”...
Construction began in 1941 and was completed in 1946 by the U.S. Navy Seabees. The scale of the original undertak- ing was extraordinary. The break- water extends approximately 2.8 miles, reaches depths of up to 36 feet and required nearly two million cubic yards of locally quarried rock fill. Its outer armor consisted of massive stones ranging from 10 to 30 tons. Treflik-Body noted that the accom- plishment is particularly remarkable given the equipment available to the Seabees at the time. Constructing and stabilizing such large stones in an active wave environment would have been a formidable challenge even with today’s technology. The breakwater also played an important historical role. During the final stages of the Second World War, Apra Harbor became a major staging area for U.S. military operations, with
the breakwater providing the sheltered conditions necessary to support naval logistics. Over the decades, however, the structure has experienced the relentless effects of Guam’s severe wave climate. Eight decades of patchwork repairs The Glass Breakwater has under- gone a series of repairs dating back to 1946. In general, the repairs were reactive, responding to damage caused by individual storms and typhoons. Documentation of damage and repairs is available from 1969 onwards. Following storm damage in 1969, addi- tional armor stone was placed on the seaward face to restore armor eroded by severe storm waves. In 1976, Typhoon Pamela resulted in extensive damage and another major repair effort. Dolos concrete armor units were also intro- duced in portions of the structure.
Photo source: U.S. Navy
The Glass Breakwater protects Apra Harbor in Guam.
October 2026 — PACIFIC PORTS — 39
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