Port commissioners approved a plan to modernize the San Diego waterfront’s 10th Avenue Marine Terminal beginning in the summer.

Meeting on Dec. 13, the board OK’d an environmental document covering the port’s plan to remake the terminal and handle more freight through it. The document foresees the port handling up to 4.6 million metric tons of cargo at the terminal, up from 1 million tons.

The original proposal called for handling as much as 6.1 million tons. Commissioners dialed back the plan “in order to mitigate significant air quality and health risk impacts,” the port said in a statement. Such impacts “are a concern given the project’s proximity to Barrio Logan and other sources of off-site pollutants, such as Interstate 5 and other large traffic generators in the vicinity.”

Work on a first phase of terminal improvements will begin in 2017, a port spokeswoman said. The $24 million, first phase of project will take slightly less than two years to complete. The port wants to demolish two 1950s-era transit sheds nestled against the berths with the deepest water. A $10 million federal grant will help pay for demolition. The port also plans to add high-mast light poles and improve railroad spurs on the terminal.

Other construction phases will follow, including the demolition of a warehouse and molasses tanks, and the installation of up to five large, cargo-handling gantry cranes. Market forces will determine how many cranes the port eventually installs, a port executive said earlier this year. An October story in the Business Journal summarized the plan.

In its Dec. 13 announcement, the port laid out several steps that it plans take to keep emissions in check. It includes a plan to buy up to 36 vehicles — forklifts, stackers and yard trucks — with zero emissions or low emissions. The port also plans to add what it calls a “bonnet system” to trap engine emissions from ships that can’t use shore power.