The newly renovated Dry Dock 4, with its initial seismic retrofit work complete five months ahead of schedule, sits ready for its next occupant at Puget Sound Naval Shipyard and Intermediate Maintenance Facility in Bremerton, Wash., on Tuesday, May 19, 2026. (Jeb Fach/U.S. Navy)
BREMERTON, Wash. — Seismic anchoring work on Dry Dock 4 at Puget Sound Naval Shipyard and Intermediate Maintenance Facility was finished in April, five months ahead of schedule, the Navy said.
The additional time will allow for supplemental construction work to strengthen the facility against earthquakes which will be carried out under the current $377.7 million contract.
The expanded project scope, enabled by the early completion of anchoring, will include comprehensive soil improvements, structural upgrades to the pump well, and additional anchors to fully reinforce the dry dock — all using the same contracting team as in the initial scope of work.
Naval Facilities Engineering Systems Command (NAVFAC) Northwest completed anchor installation in the dry dock to help ensure its resilience in the event of a major seismic event, according to the statement released Friday.
The USS Pennsylvania, an Ohio-class ballistic missile submarine, enters Dry Dock 4 at Puget Sound Naval Shipyard in Bremerton, Wash., in May 2023. (Puget Sound Naval Shipyard)
In early 2023, the Navy temporarily closed three dry docks at the shipyard after seismic assessments revealed vulnerabilities to major earthquakes. Delta Pier at the nearby Trident Refit Facility in Bangor, home to ballistic missile submarines, was also shut down.
Dry Dock 4 was completed in 1942 and can accommodate battleships and aircraft carriers. It was used to repair battle-damaged ships during World War II.
In recent decades, scientists have become more aware of the Cascadia Subduction Zone — a 700-mile-long fault about 100 miles offshore in the Pacific Ocean stretching from British Columbia to Northern California.
According to the Pacific Northwest Seismic Network, the zone has produced seven major earthquakes in the past 3,500 years, with recurrence intervals of 400 to 600 years. Other estimates put the recurrence interval as low as 250 years. The last occurred in 1700.
The National Seismic Hazard Model created by the U.S. Geological Survey estimates a 15% chance of a magnitude 8.0 or greater quake in the Seattle area in the next 50 years.
A magnitude 9.0 event could trigger tsunami waves up to 100 feet along the northwest Pacific Coast. Most Navy installations in Puget Sound are shielded from direct wave impact. However, the shaking would damage facilities, and the tsunamis could manifest as widespread flooding in lower-lying areas of Puget Sound.
New anchors in the walls of Dry Dock 4 are intended to ensure the facility’s seismic resilience in the event of an earthquake. (Jeb Fach/U.S. Navy)
The Navy announced in September 2025 that it would invest $377.7 million to strengthen Dry Dock 4.
The project is part of the Pentagon’s 20-year, $20-billion Shipyard Infrastructure Optimization Program (SIOP) to overhaul all four of the nation’s public shipyards in Puget Sound; Pearl Harbor, Hawaii; Norfolk, Va.; and Kittery, Maine.
The shipyard on the Kitsap Peninsula, just west of Seattle across Puget Sound, is the “primary provider for the maintenance, repair, modernization, inactivation and disposal of ships, submarines and nuclear-powered aircraft carriers in the Pacific Fleet,” the Navy said in a statement.
“Completing the anchor installation five months early is a monumental win for our team and the fleet,” said Capt. Preston Taylor, commanding officer of NAVFAC Northwest. “We can use this new schedule window to execute even more seismic mitigations, saving the Navy significant time and money down the road.”
The Puget Sound Naval Shipyard and downtown Bremerton waterfront. The waterways Sinclair Inlet, Port Washington Narrows and Dyes Inlet are visible in the photo. Olympic Mountains are in the background. (U.S. Navy)
