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NEWS | May 6, 2022

PNS Cuts Ribbon For Super Flood Basin After Historic First Docking

By PNS Public Affairs Portsmouth Naval Shipyard

PORTSMOUTH NAVAL SHIPYARD, Maine – Portsmouth Naval Shipyard held a brief ribbon cutting ceremony for the newly constructed Dry Dock #1 Super Flood Basin on May 5.

Honored guests at the ceremony included Chair of Cianbro Company, Peter Vigue and Senior Vice President of Stantec, David Bernier, representing the basin construction and design contract companies respectively. Participants in the ribbon cutting from the shipyard were Officer in Charge of Construction, Capt. Frank Carroll, Acting Shipyard Commander, Capt. Brian McLain and Nuclear Engineering and Planning Manager, Stephen Fahey, SES.

In April, the basin performed exactly as designed when it supported the docking of USS Cheyenne (SSN 773), a historic first in Dry Dock #1. Dry Dock #1 is the shallowest of the three dry docks at the shipyard and previously required a buoyancy assist system comprised of large floodable air-filled tanks as well as a peak high tide in order to dock and undock submarines. The Super Flood Basin, similar to a navigational lock, constructed at the entrance of the dry dock enables submarines to dock without buoyancy assist and independent of the Piscataqua River tides.

“The opening of the Super Flood Basin is a major milestone for Portsmouth Naval Shipyard ensuring we have the right capabilities to successfully execute our mission in support of the submarine fleet,” said Shipyard Commander, Capt. Michael Oberdorf. “[The week of April 11] we were able to dock Cheyenne in Dry Dock #1 without buoyancy assist tanks, a first for our shipyard. It took a great deal of planning and construction work to get us where we are today, and while we still have a lot of infrastructure optimization work ahead of us, this is a huge win for the shipyard and the Navy.”

The Super Flood Basin was a remarkable project, not only from what it delivers regarding readiness, but also the construction itself. The basin impounds more than 20 million gallons of water (40 Olympic swimming pools) at a 16-foot differential from the surrounding Piscataqua River. The Super Flood Basin project modified existing structures, parts of which were built in 1845, to allow the docking of submarines regardless of the tide.

“It truly was a team effort [among Navy leadership, Naval Facilities Engineering Systems Command (NAVFAC), Naval Sea Systems Command (NAVSEA), the shipyard and contractors Cianbro and Stantec] throughout the project,” said Officer in Charge of Construction, Capt. Frank Carroll. “From getting approval for funding, to approval to blast more than 34,578 lbs. of underwater explosives, to having three dive crews constructing simultaneously, to certifying the basin in expedited fashion, the Navy team really came together.”

The Super Flood Basin is a key project within the Navy's Shipyard Infrastructure Optimization Program (SIOP). SIOP is a holistic, once-in-a-century effort to completely update and modernize the Navy’s four public shipyards. Upgrading and building new dry docks is critical to ensure the Naval Shipyards are able to maintain and modernize the newest submarines and aircraft carriers.

“SIOP will modernize the U.S. Navy’s four public shipyards and provide needed facilities and efficiencies for generations to come,” said SIOP Public Affairs Officer Jeff Cunningham. “By modernizing the infrastructure and industrial plants, SIOP works to ensure the shipyards are able to deliver submarines and aircraft carriers out of availabilities on time to support our national security.”

With regard to Dry Dock #1, a new SIOP phase will soon bisect the Super Flood Basin and, in doing so create two additional dry docks which will complete the planned $1.7B effort to upgrade, expand, and modernize what will become Multi-Mission Dry Dock #1.

Cheyenne's docking also marks a new era at Portsmouth Naval Shipyard as she will be the first of several Los Angeles-class submarines to undergo a service life extension. In order to meet the submarine fleet's operational needs over the next decade, extending the service life of select Los Angeles-class submarines was deemed necessary while new submarines are built.

“This was an historic [event] for both Cheyenne and Portsmouth Naval Shipyard," said Cheyenne Commanding Officer, Cmdr. Samuel Bell. “This milestone is the culmination of significant effort and represents the dedication of both the Navy and the shipyard to the Los Angeles-class service life extension program. Cheyenne is setting the standard for engineered refueling overhaul excellence to benefit the follow-on submarines that will be the backbone of the fleet for decades. We are thrilled to lead this effort and pass a Bravo Zulu to Ship’s Force and the shipyard project team for all the hard work that has led to this.”

Cheyenne and her complement of more than 140 crewmembers arrived at Portsmouth Naval Shipyard November 23, 2021. Cheyenne, the final Los Angeles-class submarine delivered to the Navy, is the third ship of the United States Navy to be named for Cheyenne, Wyoming. Measuring 360 feet long and displacing more than 6,900 tons, Cheyenne is capable of supporting various missions, including anti-submarine warfare, anti-surface ship warfare, strike warfare, and intelligence, surveillance, and reconnaissance. The contract to build Cheyenne was awarded to Newport News Shipbuilding and Dry Dock Company on November 28, 1989, with its keel laid on July 6, 1992 and commissioned September 13, 1996.

Portsmouth Naval Shipyard is America’s leader for attack submarine maintenance, repair, and modernization. The on-time completion of submarine availabilities is critical to maintaining the U.S. Navy’s maritime superiority. As a NAVSEA field activity, Portsmouth is committed to expanding our undersea advantage and maximizing the material readiness of the fleet by safely delivering first-time quality, on time, and on budget.

For more information about the Shipyard Infrastructure Optimization Program, visit

For more information about Portsmouth Naval Shipyard, visit