Oregon Public Broadcasting

The Pendleton Round-Up is 100 years old. The iconic western rodeo in northeast Oregon gets under way Wednesday amid even more cowboy hoopla than usual.

Pendleton normally has a population of 17,500. This week Round-Up organizers expect 75,000 more for the rodeo. To get ready for the onslaught of revelers, one man has prepared "cattle" of a different sort. Anna King explains.

Few people want to talk to Mark Milne about his job. Even his wife has banned work talk at the dinner table.

Mark Milne: "No one plans on being a waste water superintendent or something. It's not a fireman job, it's not being a doctor. But it's a good job."

That's right. Mark Milne runs the waste water treatment plant in Pendleton.

Anna King / Northwest News Network

Mark Milne is waste water superintendent for the City of Pendleton, Ore. The town expects 75,000 visitors for it's 100th Pendleton Round-Up rodeo this week.

Mark Milne: "Well most people, they just flush and forget."

And flush they do, a lot more than usual during the Round-Up, and a lot more items than you would think.

Mark Milne: "I mean they flush anything and everything don't they? And it's amazing what people fit down a toilet."

Pills, penitentiary coveralls, kids toys....

Mark Milne: "Some things I don't even know how they get down there. I still haven't figured out the 200 feet of rope that made it down the sewer."

To take care of all that trash Milne shows me his powerful "grinder."

He proudly tells me this baby can eat through a piece of lumber in minutes. But it's not just garbage that Milne has to plan forduring Round-Up.

This rodeo is known for its copious amounts of beer and it even has a whiskey named for it. Down in the sewers, all that booze turns into a lot of ammonia and nitrates.

This treatment plan has to process a tremendous increase in waste far more quickly than usual. So Milne and his team turn to cattle....not cows though. "Cattle" is what Milne calls the bacteria that eats all that waste.

Mark Milne: "Just like if you have cows and are raising cattle, there are only so many cows you can have per acre. As the food goes up you can have more cows per acre and that's our goal is to grow more cows per acre when we get the food and then we have to get rid of those cows per acre when we don't have the food."

The wrong balance of bacteria could upset the overall system, and send germs or pollution out in to the rivers and streams.

It's not just Pendleton's sewage system that's ramping up as the Round-Up turns 100.

Carl Culham is the Secretary and Publicity Director for the rodeo. He says Round-Up crowds are usually good-humored. But there will be extra police and volunteers on hand to make sure everything runs smoothly.

Carl Culham: "I don't know if we can get too big. It might get very crowded; there might be some issues with a line at a restaurant or something like that. But you know it's Round-Up week and we want everything to be just right."

As the Round-Up gets underway, much of the work to plan and prepare is already done.

Waste water manager Mark Milne will be keeping an eye on how his sewage system handles the surge of visitors. But he and his staff plan to take Friday off, along with the most of the city.

The official slogan of Round-Up 100 is "Let'er Buck." Milne's got another saying.

Mark Milne: "Yeah, Let'er Flush!"