Keeping the Atlanta Braves’ new Cobb County ballpark looking shiny and new will be an expensive proposition, estimated to cost $65 million over the next 30 years.

Half of that cost will be shouldered by county taxpayers — in addition to the $300 million in public money the county is committing to construction.

Jim Pehrson, Cobb’s finance director, said an agreement has not yet been reached on how much money will be dedicated toward capital maintenance, but the Braves provided the county with the estimate.

Pehrson said the lease agreement will likely require both sides to make equal contributions into a capital maintenance fund every year.

The Braves announced Monday that they will leave Turner Field when their lease expires after the 2016 season. The team plans to build a new stadium and mixed-use development on 60 acres of land near interstates 75 and 285.

Under a deal negotiated by the Braves and Cobb officials, county taxpayers will cover 45-percent of the $672 million cost for buying the land, preparing the site, designing and building the ballpark. The County Commission votes Nov. 26 on the deal.

Braves spokeswoman Beth Marshall said Friday the capital maintenance fund would cover repairs or needed replacement of “anything that is affixed to the stadium,” such as scoreboards, seats, lights, turf, or plumbing.

Other upgrades, like buying a next-generation scoreboard, expanding a section of the stadium, or adding new fan amenities are not be covered by the fund and would be the Braves responsibility.

Andrew Zimbalist, an economics professor at Smith College and the author of several books on the public financing of stadiums, said maintenance deals range from teams paying none of the costs to paying most of them.

“Deals on maintenance are all over the map,” Zimbalist said, before adding that the Braves estimate “sounds skimpy.”

But it is difficult to know if the estimate is reasonable and whether the county is getting a good deal until the entire lease is final, Zimbalist and other experts say.

The Braves capital maintenance requests over the past four years at Turner Field have averaged $1.7 million — from a high of $2.6 million in 2009 to a low of $1.4 million in 2012.

Steve Labovitz, an attorney at McKenna Long & Aldridge, was chief of staff for former Atlanta Mayor Bill Campbell and negotiated the city’s deal with the Atlanta Hawks to build Philips Arena. After leaving the city, Labovitz’s first client was the city of San Diego, which hired him to negotiate with the Padres for construction of Petco Park.

Labovitz agreed that the entire lease has to be considered before deciding if the county’s maintenance agreement is a good deal for taxpayers. The county is expected to have a Memorandum of Understanding signed by both sides next week, prior to the county commission vote; the lease would be negotiated at some point after that.

“The devil is always in the details,” Labovitz said. “It will depend on the definition of what capital maintenance is. It will depend on the revenue sources. There are a million different things, and you have to look at it comprehensively.”

The Braves’ lease at Turner Field distinguishes between routine maintenance and capital improvements and repairs. The team pays directly for maintenance, and puts money into a fund for capital improvements that is controlled by the Atlanta Fulton County Recreation Authority.

The team gives the recreation authority a list of capital maintenance repairs, and the authority’s board votes to approve or disapprove those repairs. That arrangement has been a source of tension and frustration between the two sides during Turner Field’s 17-year history.

Cobb plans to get a jump on funding its share of the capital maintenance fund, Pehrson said.

One of the revenue streams the county plans to use for its share of $17.9 million in annual debt service is a new tax on businesses and apartment complexes within the Cumberland Community Improvement District, a six square-mile business corridor that includes the Cumberland Mall. Those revenues will likely begin coming in next year, but bond payments won’t begin until 2017.

Pehrson said he anticipates that revenue going into the capital maintenance fund until it’s needed for bond payments.

“That will give us a head start,” Pehrson said, who added that there will be very little spent on capital maintenance during the early years of the ballpark. “You have all the warranties, so there is very little cost on the front end.”

Beyond that, the county’s plan for payments into the fund is less clear.

Pehrson said the county expects to generate more than it needs for debt service, and that money would be dedicated to the maintenance fund. In addition to the CID tax hike, the county is adding a car rental tax and a fee on hotel stays, and it is shifting some property tax revenue.

“You’re going to have a lot of economic development that will provide additional revenue to the county,” Pehrson said. “That anticipated growth will provide additional dollars that will be identified and set aside.”