OAKLAND -- The A’s gained momentum Monday toward the construction of their proposed waterfront ballpark.

By a unanimous 7-0 vote, the Port of Oakland Board Commissioners approved a preliminary term sheet that allows the A’s and the board to negotiate details of the team’s land acquisition for the ballpark for at least four years.

A’s president Dave Kaval called the decision “a critical interim step forward.” It frees the A’s to pursue procedural matters with the city and the state of California while continuing talks with the port.

“It’s critical to be on the same page as the Port Commission when we go get other approvals,” Kaval said.

Submitting an environmental impact report will be among the A’s upcoming priorities, if not the top priority. Kaval estimated that an environmental impact report might not be completed until the end of the year, though a draft could be ready by the end of summer. The port and city council then would consider the report for approval in 2020.

Kaval reiterated his hopes of breaking ground for the new ballpark in 2021 and opening it in '23.

During the phase of the meeting reserved for public comment, dozens of longshoremen who work at the port passionately expressed concerns about the area being transformed into an entertainment district -- much like adjacent Jack London Square -- or a strip of condominiums.

Kaval maintained that the port’s maritime emphasis will remain intact, pointing out he had tailored several aspects of the ballpark’s construction or features to suit the workers’ wishes.

Board president Ces Butner insisted that preserving the integrity and the needs of the maritime industry remained the organization’s chief concern. However, referring to the ballpark’s creation, he asked rhetorically, “Why can’t we have a transformative event in our city?”

The pleas and complaints of the maritime community were loud and sincere enough to prompt the board to attach an amendment to the agreement with the A’s. The amendment basically guaranteed that essential qualities of the port would not be compromised.