Momentum is building to construct a new baseball stadium at Oakland's Charles P. Howard Terminal with the certification of a key environmental document last Thursday night. But, hard work is ahead.

The Oakland City Council voted 6-2 to certify the final environmental impact report and pave the way for a binding financial agreement between the city and the Oakland Athletics. That may happen this summer.

Once that does happen, then ground can be broken.

Councilmembers Noel Gallo and Carroll Fife opposed the certification. The project is in Fife's district, District 3.

Oakland Mayor Libby Schaaf, who will be leaving office when her term ends, spoke confidently to reporters Friday morning.

"This project is happening and it is going to happen in a spectacular way," she said.

But Oakland A's President Dave Kaval said Friday afternoon that the city and the Oakland A's still have a "huge hill to climb."

The two still must negotiate the financial details of the project, which may be the hardest part.

Kaval said negotiations over money are the hardest.

Other issues are looming, too, such as what will be in the community benefits package and how to keep pedestrians and motorists safe along the nearby railroad tracks.

City councilmembers want 15% of the housing at the project site, commonly known as Howard Terminal, to be affordable and 20% more offsite. That's just one piece of the community benefits package, but a key one.

Schaaf called it a "do or die" issue for the City Council.

The A's have a proposal before the city on community benefits including affordable housing and Kaval could not go into details. He said the city and the A's need to negotiate before making the outcome public.

Railroad tracks are near the project site and Union Pacific owns all of them in front of Howard Terminal, a company spokeswoman said.

"Union Pacific has serious safety concerns with the proposed Waterfront Ballpark District Project, and its location next to two busy rail yards and a busy passenger rail station," Union Pacific spokeswoman Robynn Tysver said.

"Union Pacific believes developing the Howard Terminal site without removing rail, vehicle and pedestrian conflicts will exacerbate roadway congestion and create significant safety risks for the public and our employees," Tysver said.

The project as it stands includes one bridge over the railroad tracks for vehicles and one for pedestrian and bicyclists.

Kaval acknowledged Union Pacific has concerns.

Including passenger rail, close to 100 train movements occur each day by Howard Terminal, said Adrian Guerrero, general director for policy and partnership at Union Pacific.

Each train stops in front of Howard Terminal for 10 to 25 minutes, Union Pacific officials said.

The collective concerns of Union Pacific, passenger rail partners, the California Public Utilities Commission and other area stakeholders "remain unaddressed in the deficient Final Environmental Impact Report," Tysver said.

"We hope the City upholds its commitments for continued discussions on these critical safety issues, and that they are formally incorporated into a needed agreement before this project moves forward," she said.

Gallo maintained Thursday night that the Coliseum is the best place for the A's. Fife asked the A's to talk with the people who live and have lived in areas such as West Oakland, which will be impacted by the project, because many people have concerns.

Kaval said a lot of community engagement has gone into the project.

Fife also wondered whether the city is beholden to the A's timeline as work toward a new ballpark is moving quickly.

Schaaf said trying to find a new home for the A's started before she became mayor seven years ago.

"This has been a very long timeline," Schaaf said.

Kaval said the A's have been working to find a new home for five years and still don't have one.