The Department of Defense has awarded Bath Iron Works an extension of a planning, maintenance and modernization contract valued at $78.7 million.

BIW was previously named the “planning yard” contractor for the Navy’s Arleigh Burke-class DDG-51 destroyers and FFG 7-class frigates. The contract announced this week by the Defense Department extends the contract for a third year. As the planning yard, BIW staff will handle design, planning and provide material support for ship maintenance and modernization.

The General Dynamics subsidiary is also planning yard for two types of littoral combat ships.

Several Arleigh Burke destroyers and Zumwalt-class destroyers are under construction in Bath. Last week, BIW crews held a keel-laying ceremony for the future USS Rafael Peralta, which is the 35th Arleigh Burke destroyer built in Bath and was named for U.S. Marine Corps Sgt. Rafael Peralta, who was killed in action in Iraq in 2004. The shipyard also began fabrication of the future USS Daniel Inouye destroyer, which was named for the late Sen. Daniel Inouye of Hawaii.

With more than 5,500 employees, BIW is one of Maine’s largest private employers.