The Portland Planning Board is set to vote Tuesday on a long-debated housing project that could reshape the Bayside neighborhood and bring 445 new apartments into the city’s tight housing market.

But it was still not clear Monday if last-minute design changes will be enough to resolve concerns about flooding a neighboring property.

“Whether the plan is feasible or not we have not yet determined,” said John Bannon, an attorney for the owners of Noyes Self-Storage on Somerset Street.

Those concerns about flooding appear to be the last hurdle for the project known as “midtown,” which was first proposed by Miami-based developer The Federated Companies five years ago.

The Planning Board is due to vote on the revised plan after a public hearing Tuesday at City Hall. The meeting is scheduled to start at 4:30 p.m. and break for dinner before resuming at 7 p.m.

The project was originally approved by the city a year ago. That original plan included four 16-story apartment towers, two parking garages and ground-floor retail space.

But that version faced strong resistance from those who said it was out of scale with the neighborhood and with the city’s downtown. A group called Keep Portland Livable sued to overturn the city’s approval, arguing that the massive project conflicted with the city’s long-term plans.

In a settlement reached in October, the developer agreed to drop the height from 16 stories to six stories, reduce the number of residential units from 650 to 445 and scrap one of the two parking garages. In return, Keep Portland Livable dropped its opposition.

Because the site of the development is in a zone that frequently floods, the city and developer plan to share the cost of raising the level of Somerset Street between Pearl and Elm streets by 2 feet.

However, the owner of Noyes Self-Storage, situated between Kennebec and Somerset streets, worries that the raised street will cause water to pool by the base of the building, penetrate the old brick walls and flood the first floor, where half its business is located.

The street-raising plan was redesigned to allay those concerns and the Planning Board vote was delayed until Tuesday to allow time to reach a settlement.

The newest design would keep the ground floor of Noyes Self-Storage 18 inches above Somerset Street, instead of six inches above, said city spokeswoman Jessica Grondin. At the current street level, there’s a 3-foot buffer.

Bannon said the city submitted its proposal to change the grading of the street to the Noyes family a week ago and his client was still reviewing the design Monday.

Raising the elevation of Somerset Street in conjunction with the project is part of the city’s long-term plan for Bayside and East Bayside – burgeoning neighborhoods with a history of flooding problems that will only get worse if sea levels rise and storms become more extreme because of climate change.

The cost of the street-raising project has been estimated at $4 million, with the city paying two-thirds of the cost and the developer covering the rest.

Grondin said the city would determine if the cost of the project would be affected, once a solution with the Noyes family was reached.