ATLANTA -- They're on the clock, but Wednesday a CBS 46 News hidden camera investigation questions whether city workers are wasting time on your dime. And here's the catch: Those same workers are racking up hundreds of thousands of dollars of overtime.

The employees work for Atlanta's Public Works Department collecting trash, but we found them sitting around, watching the clock, even playing chess, all while they are supposed to be working.

The CBS 46 Investigates Team received a tip from a whistleblower who told us knocking off on the clock is a popular practice at Atlanta's solid waste department.

"These people want to make overtime, and they are sitting in the station at 2 o’clock," the whistleblower told Chief Investigative Reporter Wendy Saltzman.

He asked us to protect his identity, obscuring his face and using someone else's voice in fear of being fired. He says he's already reported the wasted tax money multiple times to City officials with no response.

Saltzman asked who he reported his concerns to.

"My supervisor, the head of the station, the one over her, and the one downtown." But the Public Works employee says, they have done nothing about it.

So CBS 46 News took our hidden cameras in to investigate. On 6 different occasions we caught between 15 and 50 workers, sitting around, not picking up trash at 2 and 3 in the afternoon. This, even when an Atlanta Spokesperson says they're still on the clock until 4.

Saltzman approached workers who were sitting around at 3:15 in the afternoon.

"Aren't you supposed to be picking up the trash?" Saltzman asked.

The worker responded, "No. It's time for us to get off. We get off at 4 o'clock." But Saltzman pointed out it was only 3:15. Multiply that time sitting around by hundreds of workers and that's a lot of time and money, wasted.

Saltzman then approached Supervisor Artis Watts and questioned, "Why are these people sitting here instead of picking up the trash? When you guys are racking up over half a million dollars in overtime?"

Watts walked away.

Our investigation discovered Atlanta trash collectors were paid an excess of $600,000 dollars in overtime last year. In the first 6 months of this year they were paid another $311,650 for work they did after hours.

A typical workday starts at 7:30 in the morning and the shift is supposed to be over at 4.

But the whistleblower tells us these hourly employees routinely sit in the substations from 2 to 4, waiting for the overtime clock to kick-in before they finish their jobs.

"That's what the point is," he told us. "Make nothing during the day, wasting time, come here and jump in a truck and make overtime." The whistleblower says he went as far up as trying to speak with Public Works Commissioner Joe Basista, but he still couldn't get answers. All the while he was watching his friends get fired because of Atlanta's swelling budget deficit.

"I feel like management is wasting our money, and we pay for it by losing our job," he continued.

When CBS 46 went to one of the solid waste stations at 3 in the afternoon to ask questions, the workers who were sitting around on the clock scattered and a security guard tried to thrown us off us off the property.

Watts dogged question after question and the City of Atlanta Public Works Department also refused our requests for an interview, and instead provided us with this statement which says:

"Lunch breaks may be taken during the day or at the end of their shift upon completion of their assigned routes. It is not unusual for workers to work through their lunch and breaks." The statement continues, "Should it be determined any employees have violated the overtime policy, this will be dealt with in accordance with the City's standard procedures for discipline."

We are looking for answers from our public officials as we continue to dig into this waste of your money. If you see government waste, e-mail Wendy Saltzman at Wendy.Saltzman@cbs46.com.