Portsmouth Naval Shipyard Dry Dock 1 Extension and Super Flood Basin

The problem at Portsmouth is elevation. Dry Dock No. 1 was built for the boats of another era and its floor sits too shallow for a Virginia-class submarine to dock on a normal tide. The Navy’s answer is to build a 3.5-acre basin at the dock entrance that works like a navigation lock, raising the water artificially so a submarine can come in without buoyancy assist and without waiting on the Piscataqua.

NAVFAC Mid-Atlantic awarded the $1.73 billion firm-fixed-price contract to 381 Constructors in August 2021 — at the time the largest military construction contract the Navy had ever let. Only $70 million was funded at award, with the balance incrementally funded across roughly seven years. The joint venture brings together The Industrial Company, Cianbro and The Middlesex Corporation.

Project Scope

A partitioned two-bay addition to the existing WWII-era Dry Dock No. 1, designated Dry Dock No. 1 North and Dry Dock No. 1 West, plus the super flood basin at the entrance. The basin is the technically hard part: a gated impoundment in a tidal river that has to hold elevation reliably enough for a submarine to transit. The work is part of the Navy’s 20-year Shipyard Infrastructure Optimization Program and runs to a June 2028 completion.

Why It Matters

Four public shipyards maintain the entire U.S. submarine fleet, and every one of them was laid out for hulls that no longer exist. Portsmouth is the first of the four to get this scale of rebuild, which makes it the template for Norfolk, Puget Sound and Pearl Harbor. It’s also a reminder of what incremental federal funding does to a contractor’s balance sheet — 381 Constructors signed a $1.73 billion contract with $70 million behind it, and has been building against appropriations ever since.

Project Team & Details