Once he came upon a giant sea turtle whose shell was riddled with bullet holes, and he has cleaned up countless deer carcasses.
It is far from a mundane trash-collecting role.
"A lot of my job is putting out fires, drop what you're doing in an emergency," said O'Hara, 57.
He was born in Michigan and moved at age 8 with his parents to Newport Beach.
O'Hara graduated from Corona del Mar High School in 1974 and worked for the city of Newport Beach for about three years, collecting trash from residential neighborhoods.
"Looking back, it all makes sense," O'Hara said. "I'm a trash man."
He started with Laguna as a part-time employee, helping city gardeners mow the grass.
Today, O'Hara assists in multiple areas, whether it's helping lifeguards set up towers during the summer or operating an aerial lift truck that allows an investigator at a crash site to take an overhead photo of the scene.
He is dependable and knowledgeable, said Public Works Director Steve May, who met O'Hara 18 years ago when May was hired as an engineer.
"John is, and has been, an incredible asset for the city," May said. "I'm able to call him any time day or night, and he'll drop whatever he is doing."
O'Hara said now is the time to retire, but by no means is he done learning.
He is considering taking courses in public works inspection, focusing on curbs, gutters and roadways.
"I'm trying to set it up where I'm available to the city if they needed me," O'Hara said.
He'll mostly miss seeing his "working family" every day.
"You spend more time with your co-workers than with friends, spouses and girlfriends," O'Hara said.