PNS Cuts Ribbon for Super Flood Basin After Historic First Docking > Naval Sea Systems Command > Recorded News Module

PORTSMOUTH NAVAL SHIPYARD, Maine – The Portsmouth Naval Shipyard held a brief ribbon-cutting ceremony for the new #1 Super Flood Basin Graving Dock on May 5.

Guests of honor at the ceremony included Cianbro Company President Peter Vigue and Stantec Senior Vice President David Bernier, representing the basin construction and design companies respectively. Participants in the inauguration of the shipyard were the officer in charge of construction, Captain Frank Carroll, the acting commander of the shipyard, Captain Brian McLain and the director of nuclear engineering and planning, Stephen Fahey , HIS.

In April, the basin worked exactly as expected when it supported the docking of the USS Cheyenne (SSN 773), a historic first in Dry Dock #1. Graving Dock No. 1 is the shallowest of the shipyard’s three dry docks and previously required a buoyancy aid system consisting of large flood-prone air-filled tanks as well as a high tide peak in order to moor and to unmoor submarines. The Super Flood Basin, similar to a navigational lock, built at the entrance to the dry dock allows submarines to dock without buoyancy aids and independent of the tides of the Piscataqua River.

“The opening of the Super Flood Basin is a major milestone for Portsmouth Dockyard, ensuring we have the right capabilities to successfully execute our mission of supporting the submarine fleet,” said the Dockyard Commander, Captain Michael Oberdorf. “[The week of April 11] we were able to dock Cheyenne in Dry Dock #1 without buoyancy aid tanks, a first for our shipyard. It took a lot of planning and building work to get us to 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 yard and Marine.

The Super Flood Basin was a remarkable project, not only for what it offers in terms of preparation, but also for the construction itself. The basin holds over 20 million gallons of water (40 Olympic size pools) at a differential of 16 feet from the surrounding Piscataqua River. The Super Flood Basin project modified the existing structures, parts of which were built in 1845, to allow mooring of submarines regardless of the tide.

“It was really 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 Construction Officer Captain Frank Carroll. “From getting funding approval to getting approval to blast over 34,578 pounds. from underwater explosives, to the simultaneous construction of three dive teams, to the expedited certification of the basin, the Navy team really came together.

The Super Flood Basin is a key project in the Navy’s Infrastructure Infrastructure Optimization Program (SIOP). SIOP is a one-of-a-kind holistic effort to completely update and modernize the Navy’s four public shipyards. Upgrading and building new drydocks is essential to ensure shipyards are able to maintain and modernize the newest submarines and aircraft carriers.

“SIOP will modernize the US Navy’s four public shipyards and provide the facilities and efficiency needed for generations to come,” said Jeff Cunningham, SIOP’s public affairs manager. “By modernizing infrastructure and industrial plants, SIOP ensures that shipyards are able to deliver unavailable submarines and aircraft carriers on time to support our national security.”

Regarding Dry Dock #1, a new SIOP phase will soon divide the Super Flood Basin and in doing so will create two additional dry docks that will complement the planned $1.7 billion effort to upgrade, expand and modernize what will become Multi-Mission Drydock #1.

CheyenneThe mooring also marks a new era at Portsmouth Dockyard as she will be the first of several The bone Angeles-class submarines to undergo a life extension. In order to meet the operational needs of the submarine fleet over the next decade, extend the life of certain Los Angeles-class submarines was deemed necessary as new submarines are built.

“It was a historic moment [event] for both Cheyenne and Portsmouth Dockyard,” said Cheyenne Commander, Cmdr. Samuel Bell. “This milestone is the culmination of significant effort and represents the dedication of the Navy and the shipyard to the Los Angeles– class life extension program. Cheyenne sets the gold standard for technical refueling overhauls for the benefit of the follow-on submarines that will form the backbone of the fleet for decades. We are delighted 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 over 140 crew arrived at Portsmouth Dockyard on November 23, 2021. Cheyennethe 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 over 6,900 tons, Cheyenne is capable of supporting various missions including anti-submarine warfare, surface anti-ship warfare, attack warfare, and intelligence, surveillance and reconnaissance. The building contract Cheyenne was awarded to Newport News Shipbuilding and Graving Dock Company November 28, 1989, her keel being laid on July 6, 1992 and commissioned on September 13, 1996.

Portsmouth Naval Shipyard is the US leader in the maintenance, repair and modernization of attack submarines. The timely completion of submarine availabilities is critical to maintaining the US Navy’s maritime superiority. As a field business of NAVSEA, Portsmouth is committed to extending our undersea advantage and maximizing fleet material readiness by safely delivering first quality, on time and on budget.

For more information on the Shipyard Infrastructure Optimization Program, visit

For more information on Portsmouth Naval Dockyard, visit

Rufus T. Sifford