With a city-imposed deadline of Dec. 31 fast approaching, North Charleston Mayor Keith Summey said the still-anonymous buyers of the former Charleston Naval Hospital are working to close the deal by year's end.

North Charleston bought the former hospital from the federal government in the fall of 2012 and a short time later announced a $9.2 million deal to sell both the hospital and the city-owned vacant site of a former shopping center across the street.

The deal raised hopes that the city's investments in the properties would pay off, with large-scale redevelopment at the corner Rivers and McMillan avenues, including a full-service grocery store in a section of North Charleston that's called a "food desert" due to the lack of shopping options.

But the plan to sell the former Shipwatch Square/Pinehaven Shopping Center site and the vacant Charleston Naval Hospital has not been consummated, and Summey has said that if the buyers don't close the deal by the end of the year he'll take the properties to other interested parties.

"We're still working with the company, on a daily basis," the mayor said. "When you get into a complicated deal like this it can, unfortunately, take longer than I would like."

Mike Brownyard, a Mount Pleasant lawyer representing the buyer, Chicora Gardens LLC, said he expects the company to close on at least one of the two properties by year's end, but said they disagree that there's a Dec. 31 deadline.

"As far as we are concerned, we are under contract whether it closes on that date or not," Brownyard said. "It's always been everyone's goal to close, long before this."

Summey said there are other interested parties waiting, in case the sale falls through. If the sale falls through, North Charleston would keep a $1 million deposit, city officials have said.

"We spent about an hour in a large conference call with the mayor, his lawyers, his bond staff and our people," Brownyard said Thursday. "They are in the process of doing an addendum that will address all the issues that remain between the parties."

He said the development plan still calls for a grocery store, which was the city's primary goal.

"That's absolutely still part of it," said Brownyard. "There will be a grocery store there."

A preliminary site plan for the properties, shown at the end of 2012, included parks, a grocery store, office space and housing. That plan said the former 10-story hospital would be rehabilitated into a health clinic and senior living with private apartments but communal dining.

North Charleston spent about $4.2 million buying and clearing the shopping center site, and another $2 million to buy the hospital from the federal government.

Upkeep of the hospital over the past year has cost the city $617,389, not including security by city police.

South Carolina allows limited liability companies to operate with anonymity, identified only by their name and the name of the person - typically an attorney - who filed the company's paperwork. So, there's no transparent way to identify the developers behind the potential buyer, Chicora Gardens LLC.

Reach David Slade at 937-5552