The Portland Planning Board on Tuesday reviewed plans for a $10 million expansion of the city’s shipping container terminal but delayed a final vote on the project until next month pending sale and easement agreements with a neighboring landowner.

The proposal from the Maine Department of Transportation would double the size of the International Marine Terminal, directly link the port to a rail line and upgrade the terminal’s truck-loading facility. The result, according to supporters, will be an “inter-modal” terminal able to move freight more efficiently and at lower cost to customers, thereby positioning Portland to better compete with other East Coast ports.

After a detailed presentation, planning board members endorsed most aspects of the plan but held off on a final vote until MDOT has completed negotiations with Phineas Sprague Jr., owner of the boatyard that will have to give up part of its land to make room for the expansion. While the state has planned to use the power of eminent domain to claim the land, Sprague has been cooperating with the state and said Tuesday night that he was satisfied with the terms of the nearly complete deal.

Sprague described the terminal expansion as “an extraordinary opportunity” for the city, the state and the shipping line Eimskip that operates between Portland and ports in Northern Europe, Iceland and Newfoundland.

“This is a 100-year opportunity for the city of Portland and the state of Maine, and you guys are in a position where you have to get it right,” Sprague told board members.

Under the proposal, the International Marine Terminal would expand along Commercial Street to the west side of Casco Bay Bridge. The project would connect the shipping facility to the existing rail lines, allowing containers to be offloaded from ships and onto trains without leaving the facility.

Craig Morin, a consultant with HNTB who has been working with the Maine Department of Transportation, said a direct rail connection will help open additional market opportunities in the Midwest and Canada, benefiting the port, local manufacturers and Maine industries such as forestry and commercial fishing.

The project will be financed primarily through state-issued transportation bonds. Roughly 15 percent of the project’s anticipated $10 million price will go toward improving Commercial Street.

Those improvements include a realignment of Commercial Street, a signalized intersection at the main terminal entrance across from Beach Street, designated left-hand turn lanes, wider shoulders, new brick sidewalks, bike lanes, enhanced pedestrian crossings and aesthetic enhancements such as trees and traffic islands. MDOT has also worked with two businesses on either side of Beach Street – Nova Seafoods and J.B. Brown – to enhance access to their facilities.

No one spoke in opposition to the project on Tuesday, although several speakers and board members expressed concerns.

One of the biggest topics of discussion was a proposed 4-foot-high concrete wall that will be built along several hundred feet of Commercial Street on the West side of the Casco Bay Bridge. That wall will be topped with a 4-foot-high metal rail fence to accommodate the requests of neighborhood residents and city officials who want the public to be able to see into the facility.

Morin said the wall is necessary both for security and to create a strong barrier between traffic on Commercial Street and the train-loading facility, which will feature a 128-ton vehicle that will lift containers from trucks and place them on rail cars. Morin noted that the “reach stacker” machine is three times as heavy as a typical tractor trailer and will move perpendicular to Commercial Street.

“We can still maintain the safety of the site without compromising safety along Commercial Street,” Morin said.

Board members as well as a representative of the city’s planning office questioned whether a 4-foot-high wall was necessary. But Morin said the developers were open to suggestions on how to improve the aesthetics of the wall, whether through a “textured” concrete face or other adornments.

The planning board is slated to take up the proposal at its next meeting July 8.