The Northwest Seaport Alliance managing members Thursday approved $141 million worth of construction and cranes to dock two of the largest container ships simultaneously at Husky Terminal in the South Harbor.

The actions also included a 20-year lease extension, allowing Husky Terminal and Stevedoring to operate the terminal until 2046.

“This is a real historic moment for the alliance,” Port of Seattle Commission President John Creighton said during the meeting. “It’s the first major investment that the two commissions will be approving in our harbors and our gateway.”

Future Terminal 5 improvements in the North Harbor are under environmental review.

The Husky Terminal upgrades include reconstruction of Pier 4 to align it with Pier 3, creating a contiguous 2,960-foot berth, as well as the purchase of two more super-post-Panamax cranes to join two already ordered. These improvements will allow two 18,000-TEU ships to dock at the same time.

The reconstructed berth will also include conduit for future shore power to allow ships to plug into electricity while at dock.

Construction is estimated to be done in 2018.