The Chicago Fire Department will blow past its overtime budget by more than $20 million this year and Mayor Rahm Emanuel is proposing another big boost in overtime spending for 2014, prompting the head of the fire union to call on City Hall to hire more firefighters and paramedics.

Total overtime payouts will hit around $43 million by the end of 2013, fire department spokesman Larry Langford told WBEZ Friday. That’s more than double the $20 million Emanuel’s budget set aside for Chicago Fire Department overtime in his 2013 budget.

Chicago Fire Department leaders may face questions about those hefty overtime payments on Monday, when they appear before aldermen to defend their $575.7 million budget for next year. Mayor Rahm Emanuel’s proposed spending plan calls for nearly $35.4 million in overtime spending, a 77 percent spike over this year’s budgeted amount.

A crop of about 400 new fire academy graduates will just keep pace with retirements, Langford said.

“So what we’re doing now is trying to more accurately reflect the amount of anticipated overtime in 2014 so that the number that we have better reflects the reality of the situation,” he said.

The fire department’s overtime budget has grown rapidly over the last three years.

The number of sworn personnel has dropped from about 5,000 a couple of years ago, to 4,440 budgeted positions for 2014. The overtime bulge is partially due to the fact that the department hasn’t been able to train new classes of recruits for several years, as it fought a lawsuit brought by black applicants who said the firefighter test was discriminatory, Langford said.

At least three new classes will graduate from the firefighter academy by mid- to late-2014, which will mean about 405 new firefighters — just enough to fill current vacancies. Once the new classes are in place, the overtime expenses will drop, he said.

As manpower levels have dropped, minimum staffing requirements outlined in union contracts have meant that fire trucks and engines must always be staffed by at least five firefighters, while each ambulance needs at least two paramedics. That’s also driven up overtime costs, Langford said.

But Tom Ryan, president of the Chicago Firefighters Union Local 2, told WBEZ Friday the overtime bump shows that Chicago needs to bring overall staffing levels higher.

“We are losing valued members of this department,” Ryan said. “A lot of experience is walking out the door, as they should after a long career. And we’d like to see…younger people come onto the job.”

Public safety overtime spending will spike under Emanuel’s proposed budget proposal. Chicago police overtime alone would more than double, from $32 million in this year’s budget to $71 million in 2014. Police Superintendent Garry McCarthy revealed last week the city will actually end up spending about $93 million on overtime by the end of the year, prompting some aldermen to question why Emanuel doesn’t want to hire more cops to deal with the city’s violence problems.

The fire department has also felt the pressures of Chicago’s gun violence, Ryan said.

“A lotta those [victims] were saved, and that was due to the efforts of Chicago’s firefighters and paramedics who are out there every day on the front lines dealing with these issues when people decide to shoot one another,” he said.

The city also will train a new crop of paramedics next year, though Langford did not have details on how many, or when they might join the ranks.

He said the Chicago Fire Department is expecting 135 firefighters to come out of the newest class, which enters the academy Nov. 18th. It’s looking for 270 more hires from two more classes scheduled to graduate later in 2014.

Alex Keefe is political reporter at WBEZ. You can follow him on Twitter and Google+