Hamilton County Mayor Jim Coppinger told commissioners during a budget work session Tuesday the county was considering selling its Silverdale facility to Corrections Corporation of America, the private company that runs the workhouse now, and having CCA build and operate a new jail to replace the county's aged downtown facility.

Coppinger said he would soon come to the commission and ask it to hire the PFM consulting firm to research the move.

"We are looking at total privatization of our jails and our Silverdale workhouse," Coppinger told commissioners.

But Coppinger said Tuesday it wasn't set in stone. The study, which is expected to cost six figures, will guide them.

"If it makes sense, we'll do it. If it doesn't, we won't. But we know one thing: In a couple of years, we are going to have to replace that jail," Coppinger said. "And we are just looking for a way to keep the taxpayers from paying for that."

But still, the county's Silverdale contract with CCA runs out in April 2016.

Costs at Silverdale increased by $1 million in the proposed 2016 budget, because of a population increase of 7.1 percent at the workhouse.

And the cost of housing prisoners at the jail is ever-increasing, Coppinger said.

The proposed budget projects the jail operation's budget at $12.2 million, up from $12 million last year. And $10 million of that is in salaries and benefits.

Coppinger said CCA can run the jail cheaper than the county, and it could greatly reduce the cost and liability to the taxpayers.

That would in part mean some of the 173 positions in the sheriff's jail budget could be in jeopardy, although Coppinger said Tuesday part of any negotiation with CCA would include discussions to get current jail employees hired with CCA.

The announcement set off alarms at the sheriff's office.

Sheriff Jim Hammond fired off a statement late Tuesday saying the jail was not being sold and "the future careers of his staff in the jail is a non-negotiable."

Hammond said the study was only a study. After years of concerns from the grand jury about the jail's condition and manpower needs, he said it was time to start addressing the issue.

"I felt like we needed to do a study to see what options are available to us," Hammond said. "I don't think [Coppinger's] asking to close the jail or sell the jail. I think he's just asking to study the situation."

Hammond is concerned about his staff, but some human rights group are concerned about privatizing at all.

Hedy Weinberg, executive director of the American Civil Liberties Union-Tennessee, said the county's prisoners should not be put in the hands of a private company.

"As a private corporation, CCA's obligation is to maximize its profits, often at the cost of compromising public safety and accountability. Evidence of cost savings in private jails and prisons is mixed at best," Weinberg said in a statement.

She said numerous government and academic agencies that have studied private jails have found no advantages.

"The bottom line is that private prisons are accountable to shareholders, not taxpayers. We urge Hamilton County to proceed very cautiously and not to relinquish control of its jails to CCA," she said.

Alex Friedmann, managing editor for Prison Legal News, a monthly publication that covers the criminal justice system, said it's almost impossible to say whether operation by CCA would even be cheaper.

"Silverdale has been operated by CCA since the 1980s, there's not really any other benchmark to say they've saved money," Friedmann said.

But he said it is true that private companies can make a profit running jails, mainly because salaries and employee benefits are much lower.

"If CCA couldn't make a profit on running the jail, they wouldn't run it," he said. "The problem is the type of people you are able to hire at these lower wages tend to be of a lower quality in terms of training."

Friedmann speaks from experience, having been a CCA inmate for six years. Since then, he won a five-year lawsuit against CCA through the Human Rights Defense Center, of which he is associate director. The suit, which ended in 2013, forced CCA to comply with state open records law.