How one Bay Area janitor made $276,000 last year

The average janitor earns $26,180 a year . But one San Francisco-based janitor has managed to increase that average tenfold. Liang Zhao Zhang, a BART system service worker, raked in over $275,000 in 2015, thanks to overtime pay.BART spokesperson Alicia Trost confirmed that Zhang made a base salary of $57,945 and $ 162,050 in overtime pay. Benefits brought him to a total of $276,121.

This is the third year in a row the janitor has made a six-figure salary.

While researchers at Transparent California, the nonprofit that released the 2015 public employee compensation data, call BART's compensation packages outrageous and irresponsible, Zhang isn't the one to blame, according to his employers. He "signs up for every overtime slot that becomes available," Trost tells CNBC. "He is likely working almost every day of the year cleaning our stations."

SFGate reports that Zhang clocked over 4,000 hours in 2015. To put that into perspective, the typical BART employee works about 2,000 hours per year. 

"He is signing up for time that is also available to others," Trost explains. "If he doesn't take the hours, someone else will. The sign-ups are based on seniority."

It's difficult to determine exactly how much Zhang makes per hour — overtime pay is different depending on the type of shift — but SFGate estimates that he is "making roughly $56 an hour before taxes and when you pull out benefits from his salary."

While a $276,000 salary is impressive, it's not even close to what the head of BART pulls in: Grace Crunican, who was named general manager of the transit system in 2011, brought home $458,810 in total pay and benefits last year, according to Transparent California .