HIALEAH (CBS4)- More than a dozen laid off firefighters will be rehired in Hialeah, but there is no set date for their return.

Last December, Hialeah Mayor Julio Robaina said the move was needed to save the city money, up to $2.5 million.

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“The leaner we become and still provide services to our residents, the more efficient we’re being, the better we’re using our dollars,” Robaina said in December.

Five months later, the layoffs have cost the city money — nearly $10,000 a day in overtime and back pay based on union estimates, CBS4 news partner The Miami Hearld reported.

The firefighters are expected to return to work, according to city officials, but it is not clear when.

“It’s a process. It’s being worked out. It will be shortly,” said Fire Chief Marcos De La Rosa.

Until the veteran firefighters return to their positions, Hialeah is paying overtime to fill the vacant senior positions. Eventually, Hialeah will have to return back-pay to the laid-off firefighters. That could be expensive.

According to union estimates, it costs just over $4,500 to staff the senior positions — and every day the firefighters are off the job, the city owes another $5,404 in back-pay. Overall, union leaders estimate the layoffs have cost Hialeah over $1 million since Robaina issued the termination letters on Dec. 3.

The fire chief did not dispute those numbers, but said he has not crunched the numbers.

“I haven’t looked at them the way [the union has] evaluated them,” said De La Rosa.

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Asked whether he thought the layoffs were a good financial decision, De La Rosa said “that determination is not mine.”

As of March 31, with six months left in the fiscal year, Hialeah had spent 82 percent of its $800,000 overtime budget for the fire department and had $4,017 remaining from its $301,377 budget for executive salaries in the fire department.

The layoffs last December sparked a fight that went to arbitration. In April, a Fort Myers-based arbitrator, Robert Hoffman, ruled Hialeah fired the 16 firefighters without cause and that the city failed to analyze any savings. In his own calculations, Hoffman said any savings were much less than $500,000 and “may be none at all.” Hoffman ordered the city to rehire the senior firefighters — all veterans enrolled in the city’s deferred retirement program — and repay them back wages.

In May, the firefighters and union leaders marched to the mayor’s office, asking when they could go back to work. Robaina said then that he was evaluating all the options, including a possible appeal, and had to wait for the results from a union vote on a proposed contract with more than $3 million in concessions.

A few days later, the city’s outside legal counsel, William Radford, indicated in a letter to the state’s Public Employees Relations Commission, or PERC, that Hialeah would rehire the firefighters.

“Despite the fact that the City contends the Arbitrator Hoffman exceeded his jurisdiction in making his Award in this case, the City is nevertheless making arrangements to reinstate all sixteen grievants with back pay and otherwise fully comply with the arbitration Award,” Radford wrote.

The leader of the firefighters union, Mario Pico, said the city is creating an economic problem.

“The mayor [Robaina] is lying to the state in that ruling because he has not reinstated the individuals and he’s lying to the citizens because he’s not appealing the decision. The only logical conclusion is that for his political expediency he’s having the citizens waste $10,000 a day,” said Pico, president of the Hialeah Association of Firefighters IAFF Local 1102.

“My ultimate concern is that once he [Robaina] leaves, this mess is going to have to be cleaned up by the next mayor, the employees that remain and the citizens of Hialeah,” Pico added.

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On Monday, Robaina’s resignation as Hialeah took effect and Council President Carlos Hernandez was sworn in as acting mayor. Following the afternoon ceremony at City Hall, Hernandez said he understood a resolution was in “process.”