The longstanding and at times violent protests against Atlanta's planned police and firefighter training center are partially responsible for a nearly $20 million rise in costs connected to the project, city officials said.

The 85-acre (34-hectare) project, which critics call "Cop City," is now expected to cost $109.65 million, up from a previous estimate of $90 million, Atlanta Deputy Chief Operating Officer LaChandra Burkes told City Council members on Wednesday.

Atlanta has already committed $67 million toward the project, but Burkes emphasized that taxpayers would not be on the hook for the newly incurred security, insurance, legal and construction costs. She said that money already set aside for contingencies, as well as private donors to the nonprofit Atlanta Police Foundation, would pay for the costs. The foundation is leading construction of the project.

"We are confident, in working closely with the foundation, that any gaps in this project will be filled," she said.

Burkes said the "Stop Cop City" movement is responsible for 23 acts of arson that have damaged or destroyed 81 items, including construction equipment and police vehicles.

Officials have both increased the number of police officers assigned to guard the site at all hours, and have taken on $6 million in outside security costs to protect companies and people who have received threats from self-described "forest defenders." The attacks have also caused the project's insurance costs to rise by $400,000, Burkes said.

"The frequency and intensity of the attacks in opposition of the training center ... have contributed significantly to an increase in the estimated cost," Burkes said.

Atlanta has also accumulated more than $1.2 million in outside legal fees to defend itself against multiple environmental lawsuits against the project, as well as a referendum campaign that officials are trying to quash.

The fight over the training center in DeKalb County has gone national, with opponents saying the facility will worsen police militarization and harm the environment in a poor, majority-Black neighborhood. They say the city's fight against the referendum is anti-democratic — and dovetails with their concerns about a violent police response to protests and prosecution of dozens of opponents on racketeering charges.

Supporters of the training center, including Democratic Atlanta Mayor Andre Dickens, say that the city must replace outdated facilities and that it is key to train officers better to avoid improper use of force.

Officials have repeatedly made changes to the project in order to respond to local residents' concerns. Burkes said those tweaks — which include changes to the training center's layout and the addition of a 100-foot (30-meter) tree buffer around the property — are another significant reason for the rise in costs.

Burkes said all of the pre-construction work has been completed and that crews are in the "beginning phases of the actual construction work," with the project expected to be completed by December.