ALAMEDA — Up to 760 townhomes and apartments are on track to be built at the Alameda Marina as part of a $57 million project that will include shoring up its crumbling seawall along the Oakland Estuary.

The City Council voted unanimously early Wednesday morning to approve a master plan and environmental impact report for the ambitious effort at 1815 Clement Ave., which is expected to take up to 15 years to complete.

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The decision came after the council heard from a string of public speakers — 38 initially signed up — and it followed about 75 community meetings over about the past six years as well as 10 meetings involving the Planning Board.

“This is a great project,” resident Victoria Fierce said, adding that the project will improve the marina’s infrastructure while creating affordable housing. “We need housing — plain and simple.”

The project calls for 250,000 square feet of maritime commercial space and about 4 acres of public open space along the shoreline, including an area set aside for a future portion of the San Francisco Bay Trail. The new facilities will include using a dock originally constructed to build segments of the Posey Tube — which motorists use to travel under the estuary from Alameda into Oakland — into a spot for launching kayaks and other watercraft. There also will be a 530-slip marina and a 60-boat dry storage yard.

While the 44-acre site has dry storage now for about 250 boats, just 165 spots are being used, and only 49 of those boats are registered and insured, according to the developer. The aging marina also has parking spots for recreational vehicles. Much of its shoreline breakwaters, bulkheads and piers — built in the 1940s — have deteriorated, which helped spur the redevelopment plan.

Fixing the marina’s 4,009 lineal feet of shoreline — which has sustained soil loss and cave-ins because of the complete loss of steel pile walls — is alone expected to cost $15 million to $17 million. The upgrades are also necessary because of anticipated sea level rise over the next 50 years, according to Pacific Shops, the site’s owner and developer.

Pacific Shops owns all of Alameda Marina except for 17 acres that includes land along the estuary and submerged land under the estuary that it leases from the city of Alameda. The estimated cost to upgrade the slip area of the marina, including dredging, pier and dock improvements, is put at $3.25 million to $4 million.

“This project looks like a really good solution to a deteriorating infrastructure,” said Michael McDonough, the Alameda Chamber of Commerce’s president.

Resident Dorothy Freeman, however, said too much housing was proposed, and that the plan needed to include businesses for future residents to purchase groceries and other necessities because otherwise traffic will increase in the surrounding neighborhood.

As part of approving the master plan in May, the Planning Board required that half of the housing be rentals and half be made available for ownership. Some 104 apartments would be designated as affordable. Rachele Trigueros, a senior policy manager at the Bay Area Council, a business-sponsored, public policy advocacy organization, told the council that not enough housing is being built throughout California to accommodate population growth.

And the result is displacement of residents, rising rents and increased traffic as people move to more affordable places to live but still must commute to work in the Bay Area’s urban hubs, Trigueros said. The Alameda Marina project will help address some of those problems, she said.