For drivers headed north on the Lake Pontchartrain Causeway, the picturesque Mandeville lakefront’s stately homes and spreading oaks emerge gradually from the horizon, a bucolic welcome to the north shore.

But one part of that view, just east of the Causeway, doesn’t match the rest. It’s neither stately nor bucolic: a 78-acre overgrown vacant lot, a sandy scar on the city’s best feature.

That scar — what remains of the old PreStressed Concrete factory site, which provided much of the concrete for the bridge that brings thousands of cars to Mandeville each day — has lain dormant for decades. But that could finally be changing: The parish’s Planning and Zoning Commission has before it a plan to develop the site with homes, stores, a marina and a hotel.

Like any major development in Mandeville, however, the plan faces challenges. Residents have voiced serious concerns about traffic, the proposed density of the residential development and whether it would mesh with the surrounding area.

The commission will have to examine those questions before it makes a recommendation — in September or October at the earliest — to the City Council, which will have to approve or reject the ordinance defining the plan.

But many agree on this: The site is long overdue to be developed.

“This has been part of the city’s comprehensive plan for probably 25 years,” said Nixon Adams, a member of the Planning and Zoning Commission. Getting the site back into commerce is a project “everybody in town has wanted to start for a long time,” he added.

Those long-held hopes first got a glimmer of reality earlier this year when the owners of the property, Michael and Marc Pittman, commissioned an architectural firm to hold several public meetings on what to do with the property. Architect Steven Oubre presented general plans for a mixed-use development called Port Marigny that would contain houses, apartments, condominiums, retail shops, a hotel and a marina.

Those plans inched closer to reality this summer when the developers submitted a series of documents — including a 75-page “Master Plan and Guiding Principles” book — to the city for review.

While many were heartened by what they saw, not all were sold on all the elements.

“The city is faced with tremendous opportunity and tremendous risk,” said Councilman Ernest Burguières, who said he plans to take a long, hard look at the potential impact of such a large development in one of the city’s oldest areas.

“A decision this year will have consequences for decades,” Burguières said. To help allay concerns, he has submitted a list of questions to the project’s authors.

Chief among the concerns is traffic. The current plan calls for 429 residential units, including apartments, condos and houses. It also envisions a 120-room hotel plus retail shops and a marina.

That’s a lot of additional cars on local streets, none of which are wider than two lanes. And the main artery through the area, Monroe Street, frequently clogs at its intersection with East Causeway Approach during peak traffic times.

Councilwoman Carla Buchholz, whose district includes the site, pronounced herself impressed with the overall plan. “But I have concerns about how they are going to move people in and out of that area,” she said.

The Pittmans have commissioned a traffic study to examine how the Port Marigny development would affect the traffic flow, and the city has hired a traffic consultant to review that study.

Similar worries have been voiced about the development’s density. The 429 residential units could mean 1,000 or more new people in town, a significant addition to a city of about 12,000. Those extra residents could provide a boost to the city’s economy, but they could also put additional strains on infrastructure.

The Pittmans have shown sensitivity to that concern, lowering the residential unit count from about 600 when the idea was first floated earlier this year to the current 429.

“The density has changed a lot,” Councilman Rick Danielson acknowledged. Wherever that number ends up falling, it will have to be acceptable to the city and its residents, he said.

Regardless of what the concerns are now, all involved expect a lengthy review process. The Planning and Zoning Commission has scheduled three special meetings — Aug. 18, Sept. 1 and Sept. 29 — just to discuss Port Marigny, and more may be added, if needed. The city has hired David Bailey, a city manager from Florida, to help local officials review the overall plan.

Planning and Zoning has the option of recommending the plan to the council, recommending it with modifications or urging the council to deny it. The council then will have to greenlight the project or send the developers back to the drawing board.

If approved, it will take years to build.

Port Marigny “means a lot” to Mandeville, Danielson said, adding that it would forever change the city. His colleague Burguières agreed.

“I hope it goes ahead and succeeds,” Burguières said. “Nobody wants a failure.”

Follow Faimon A. Roberts III on Twitter, @faimon.