Veteran documentary editor, producer and director Sam Pollard has seen a lot during his 30 years in the business, but what happened in Centreville, Ala., in March, while filming his latest doc, “Slavery by Another Name” for PBS, caught him by surprise.

Based on the 2009 Pulitzer Prize-winning book by Wall Street Journal writer Douglas Blackmon, which challenges the belief that slavery ended with 1863’s Emancipation Proclamation, the doc recounts how in the years following the Civil War, new forms of forced labor emerged in the American South, trapping hundreds of thousands of African Americans in a brutal system that lasted until the onset of World War II.

But Centreville mayor Tom Bamberg blocked Pollard’s crew from filming in a local park.

During their seven-day Alabama shoot in late March, the crew filmed in various locations in and around Centreville, but when it came time to shoot a reenactment scene in the town’s Cahaba Park, they were told that the park’s pavilions were rented out and the grounds were unavailable.

Blackmon then contacted Bamberg via email asking for specific rental times and for permission to shoot in areas of the park away from the pavilions.

Bamberg’s emailed response was: “I do object to this being filmed in our park. I also object to it being filmed in our city. We are a quiet, small town, and I don’t want this to cause controversy.”

Pollard, who has worked on numerous race-related docs, including Spike Lee’s “When the Levees Broke” and “4 Little Girls,” as well as HBO’s feature length documentary, “By the People: The Election of Barack Obama,” says he was startled by Bamberg’s words.

“I’ve worked on a lot of documentaries, and sometimes you run into people who don’t want to be interviewed,” Pollard says. “But this was the first time a community, led by the mayor, said that we were not welcome. It was surprising, because this is 2011, but I guess (Bamberg) felt that we were going to open up a can of worms that he didn’t want opened.”While Blackmon contends that the city’s decision to bar the crew to film from Cahaba Park was illegal and a violation of First Amendment rights, Centreville city attorney Mike Hobson maintains that Bamberg’s initial explanation and not the mayor’s subsequent email was the real reason behind the park’s off-limits status.

While Hobson denies that Pollard was banned from filming in the park, he did add that “they wanted to film with actors dressed in old-time prison garb, and he wanted to depict those actors as being slaves who were tied to a stake driven into the ground. He wanted to do that in a public park on a weekend when other people were using the park for recreational purposes. We didn’t think that that was appropriate, and we felt like that would cause controversy. So, yes, the mayor had a problem with that.”

Hobson then explained that the crew needed a license, which Blackmon contests.

The specific scene, which Pollard says was a reenactment on a farm using a historic structure in the backdrop, was subsequently shot at another location.

“This is the first time in the 10 years since I started researching and writing the book that the door was so overtly slammed in my face,” Blackmon says.

The doc, being produced by Twin Cities Public Television, with an estimated budget of $1.5 million, received funding through grants provided by orgs including the National Endowment for the Humanities and the W.K. Kellogg Foundation.

“Slavery by Another Name” is scheduled to air on PBS in 2012.