Potomac, fifth U.S. Navy ship to bear the name, was laid down at Sun Shipbuilding and Drydock Company at Chester, Pennsylvania, on 9 June 1955 and launched on 8 October 1956, sponsored by Mrs. T. H. Robbins, Jr. She entered non-commissioned U.S. Navy service under the control of the Military Sea Transport Service (MSTS) with a primarily civilian crew on 30 January 1957.

Two men were killed in the explosions, and the forward part of the ship was declared a total loss.

A disastrous waterfront fire was avoided by the prompt heroic action of Potomac crew members, United States Coast Guard personnel, and U.S. Marines, who prevented the fire from igniting large fuel storage tanks adjacent to the pier.

A new bow and forebody was constructed at Sun Shipbuilding and Drydock Company in Chester, Pennsylvania and welded there to the salvaged stern section, with the bridge and crew accommodations aft.

The reconstructed ship, SS Shenandoah, entered service in 1965 and became USNS Potomac (T-AO-181) in 1976 when purchased by the Military Sealift Command