ST. PETERSBURG — A Miami developer is planning what could be a $2 billion project that would transform a now-sleepy area south of downtown St. Petersburg.

The project by Royal Palm Companies would include both affordable and high-end housing on roughly 50 acres bordered by Fourth Street S and Bay Street, and 14th and 18th avenues SE, according to property owners who have been approached about selling. The area just south of Bayboro Harbor and bisected by Salt Creek is currently home to some '50s-era houses, a few commercial businesses and the Salvation Army's administrative headquarters for southern Pinellas County.

Royal Palm executives did not return requests for comment. The company's website said it has developed more than 50 projects in Central and South Florida, including the 60-story Paramount Miami World Center under construction with 500 condo units and 450,000 square feet of retail space. It is the second-largest planned community in the nation, the website said.

Jan Hawk, who operated Hawks Diesel on 1400 3rd Street S for several decades, said two Realtors working for Royal Palm first contacted him and other owners about a year ago.

"They literally knocked on doors and said, 'Do you want to sell?' '' Hawk recalled. He initially declined but is considering an offer for an amount he would not disclose. The 60-plus page contract includes conditions that he considers unacceptable.

"I'm still telling them 'no' until they snap out of it,'' he said. "I want a real contract.''

The city has been trying with mixed success to revitalize neighborhoods south of its booming downtown. However, the low-lying area east of Fourth Street S where the Royal Palm project would go is in a coastal high-hazard zone at risk of extensive flooding. The St. Petersburg City Council is about to consider changes that would allow for increased density in high hazard areas with the caveat that new construction be flood resistant and environmentally friendly.

Hawk said he had attended recent meetings on the proposed changes where Royal Palm representatives also were present.

"Everything is contingent on high hazard zones and you know how the city moves — glacially,'' he said. "They're not going to start this (project) tomorrow.''

READ MORE: As flood risk rises in St. Petersburg, city weighs whether to allow increased development in flood zones

On Friday, Mayor Rick Kriseman said, "I am excited about this project and believe it will further stimulate an area of our city that is on the cusp of its own renaissance, but there will be strict development standards to account for the geography and our changing climate. The developer's compliance with these standards will complement the work we're doing citywide to adapt to sea level rise, high tides, and heavy rain."

City Council member Gina Driscoll, whose district includes the Bayboro area, said she did not know much about the project. She said her main concerns would be its location in a "vulnerable'' part of the city and its environmental impact on Salt Creek.

Driscoll noted that many properties near the creek had been neglected over the years. "In general, that's an area that could be put to better use,'' she said. "Whether this (development) is a better use remains to be seen.''

The Salvation Army owns a large tract at 340 14th Ave. S where its regional headquarters provides social services and emergency shelter.

"There are developers that have reached out to the Salvation Army and we are exploring future options,'' said Lt. Col Gary Haupt, the organization's area commander. He acknowledged hearing the name Royal Palm but said "we have no commitment with them at this time.''

Also included in the proposed development area is a parcel leased to a company that makes floating docks. Hawk said the trust that owns the property has agreed to sell; its managers could not be reached for comment.

A Pinellas County native, Hawk said he has mixed feelings about a huge new project in an area perhaps best known for "Thrill Hill'' — a large hump on Third Street S — and the once bucolic Salt Creek, where he canoed as a kid to Lake Maggiore.

"It isn't what I envisioned growing up,'' he said,''but we have more people than we have places to put them.''

William Felder, who recently bought and is rehabbing an 84-year-old house near Hawk's property, said he hasn't been approached about selling. But he would, if the price is right.

"I've been surprised,'' he said, "that development has been so slow moving from downtown.''

Contact Susan Taylor Martin at smartin@tampabay.com or (727) 893-8642. Follow @susanskate.