CHICAGO (CBS) – Deputy Chief Jeffrey Horan is currently the highest earner of Chicago Fire Department overtime and supplementary pay in the city, making more than $87,000 in overtime from January to June. That’s on top of his $156,000 salary.

Horan is poised to take home more than $332,000 for the year. He’s on pace to hit more than $175,000 in overtime this year, which puts him well above his 2017 total of $114,000 and far beyond his 2016 total of nearly $78,000.

Deputy District Chief David Dietz is in the same boat. He’ll hit $162,000 in overtime, far above his previous years totals, if he keeps up this pace.

The same is true of Deputy District Chief Charles Maes. He’s on track to hit $155,000 in overtime this year alone.

“People are literally doubling their paychecks with overtime and supplementary pay,” said Adam Andrzejewski, CEO and found of OpenTheBooks.com.

Andrzejewski leads the watchdog organization and has been investigating these overtime expenditures for years. He says the problem has gotten noticeably worse.

“Overtime pay is expensive. It’s expensive to taxpayers, and city resources are being mismanaged and squandered because of the lack of staffing level within the ranks of the city agencies,” Andrzejewski said.

The Chicago Fire Department told CBS 2 that these deputy district chiefs are making up for vacancies, and it all has to do with pensions.

Many employees at that rank have resigned from their exempt positions and returned to the rank-and-file in order to get the best pension deal, and then it’s hard to fill their spots.

A CFD spokesperson said the Commissioners’ Office and the Office of Budget Management are aware of the issue.

“This is another example of the pay and benefit systems within the city that are completely broken,” Andrzejewski said.

The fire commissioner earns about $200,000 a year, and the mayor earns about $216,000 per year.