For an important redevelopment project like that of New Haven’s waterfront, it’s never too early to start planning — even for something as mundane as the plumbing.

Like the sewer system, the funding and property acquisition phases of the redevelopment of River Street, in the southern half of Fair Haven, are also on schedule. In the end, the 42-acre blighted tract will become a blend of light industrial, commercial and residential complexes separated from the Quinnipiac River by a strip of open space.

“It takes time these things to come together,” said Helen Rosenberg, a New Haven business services officer. “Hopefully, this will work out.”

The project is expected to take as long as three years.

Currently, a junk yard belonging to Lloyd Terminals Inc. and an inactive 8-acre Hess oil distillation plant occupy large sections of the River Street tract. Other occupants include a Meyers Distributors’ warehouse that is 80 percent vacant, an inactive DuPont chemical distribution center, and the Regan Metals scrap yard.

But that could soon change.

Three times over the next two months, New Haven’s Board of Aldermen will review a proposal from the City Plan Commission to change River Street’s zoning. The changes are designed to prevent industrial storage centers from remaining on the redeveloped land.

“What is restricted are land-hungry uses that bring things in from the outside, like scrap metal yards,” said Karyn Gilvarg, the executive director of the City Plan Department.

But not all firms currently located in the zone will be forced to leave under the redevelopment proposal.

“We are encouraging some current business types to stay, such as printing houses and light manufacturing firms,” Gilvarg said.

The city hopes to create a mixed-use center to augment the recent rise in housing construction and renovations in Fair Haven’s nearby residential areas.

“Those uses also do not fit in with the nearby neighborhoods,” Gilvarg said.

In January, the Board of Aldermen approved the state’s designation of the 42 acres as part of a municipal development plan, allowing the city to acquire properties via eminent domain and apply for state financial assistance. The city has already entered negotiations with property owners to begin the process of purchasing land.

So far, the negotiations have been cordial.

“They’re not all saying OK, but there are discussions going on, and that’s the important thing,” Rosenberg said.

To facilitate the process, the city is obtaining updated appraisals of many of the River Street properties, Rosenberg said.

The entire project is expected to cost $20 million. On April 17, the Board of Aldermen’s Community Development Committee will review an application requesting $8 million in state aid for the project. The board also approved $10 million of municipal bonds for the project in early January. Contributions from private developers should cover the rest of the cost.