Norfolk Naval Shipyard (NNSY) held a groundbreaking on Jan. 23 to renovate Dry Dock 4. The U.S. Navy said the renovation effort will cost $200 million and take almost three years.

This makes it the largest NNSY initiative under the larger $21 billion 20-year Shipyard Infrastructure Optimization Program (SIOP). The Navy said this renovation will meet the service’s needs for submarine overhaul in the 2020s and beyond for Ohio, Virginia, and Columbia-class vessels.

Dry Dock 4 first opened in 1919.

The Navy plans by 2031 to begin replacing its current fleet of 14 Ohio-class ballistic missile submarines with a fleet of 12 Columbia-class boats. The program is expected to cost roughly $130 billion, according to the Government Accountability Office.