ALL SUMMER LONG, something magical took place on Manton Street in South Philadelphia, where a long-abandoned "pocket park" had been neglected and overgrown with weeds for the past 20 years.

In June, after neighbors Mark Berman and Jessica Calter sent out notices seeking volunteers, residents came together to clean out the weeds, dirt, construction debris and wildly growing ivy.

"We met every single Tuesday night, rain or shine; we didn't skip a week from June until November," said Berman, president of the Friends of Manton Street Park & Community Garden.

They are sophisticated city dwellers who didn't embark on the project blindly, getting the OK to work on the park both from a staffer in Councilman Frank DiCicco's office and the Parks and Recreation Department.

The group's cleanup efforts - from clearing out overgrown weeds and grass to powerwashing the concrete and brick pavers - were so successful that Manton Street Park was featured on the South Philly Garden Tour in September, Berman said.

But the good news was turned upside down last month.

That's when the volunteers learned that in August the park, at 4th and Manton street, had been placed on a list of vacant lots the city wanted to sell to get rid of blighted properties .

Now Berman, Calter and other park volunteers are caught up in a government tailspin of miscommunication, outdated databases and a plan launched in April 2010 to rid the city of vacant lots.

It wasn't until residents saw surveyors on the property last month that they learned the park lots had been bundled for sale with a group of vacant lots across the city in an ordinance DiCicco introduced in May. The measure was passed by City Council in June and signed by Mayor Nutter in July.

Unfortunately, for the Manton Street volunteers, officials at Parks and Recreation had been relying on a 1990s-era database, which showed the lots as a city park, said Michael DiBerardinis, deputy mayor of environmental and community resources and commissioner of the Parks and Recreation Department.

"I feel bad about it and I'm sure they do, too." DiBerardinis said of the volunteers. "The assumption that it was in our inventory was not the right one."

The city began the process of selling the park in August, said John Herzins, deputy commissioner of the Department of Public Property.

And without their knowledge, the volunteers contend, much of the park - along with another lot next to it - was put up for auction Oct. 7.

Herzins insists that the department posts signs on all of its properties, but both Berman and Calter said they never saw a sign.

Officials told them the winning bidder - whom the city has declined to identify - has until today to finalize the sale, Berman said.

So yesterday, armed with 340 signatures on petitions they gathered by going door-to-door and on Change.org, Berman, Calter and a handful of other neighbors met with DiCicco for about 30 minutes.

Calter said they need the name of the potential buyer because the group is considering filing an injunction to block the sale.

"He [DiCicco] said he would do what he could in the time he has [before leaving office this month] to find out the buyer's name before Council breaks for recess," said neighborhood resident Kathy O'Neill. "He was very cooperative and seemed willing to help. We are going to take him at his word."

DiCicco declined to comment to the Daily News.

His staffer, Nick Schmanek, said it was not the first time that small neighborhood parks have been placed on the city's auction list of vacant or abandoned lots.

Earlier this year, with the help of Councilman Darrell Clarke, residents in Northern Liberties were able to keep their "Spooky Garden" neighborhood park - famed for its Halloween traditions - from being sold after it was listed on Craigslist.

"Sometimes we are able to save them, but sometimes we can't," Schmanek said.

Although the residents want to block the sale, Herzins said it may not be possible. "We have an agreement for sale. It's a legal document," Herzins said.

The neighbors learned after filing an open-records-act request that a man named Kevin O'Neill applied for a zoning permit last week to build three single-family homes on part of the lots where the park is and on an adjacent lot.

Calter said she is worried that the neighbors who came together to remake the park have lost faith in working to restore their community.

"What upsets me the most is that people feel like they've gotten burned and don't want to try again to beautify the neighborhood," Calter said, "because it could just get taken away from you."