MINNEAPOLIS (WCCO) – Each year the five animal barns at the Minnesota State Fair serve as temporary lodging for about 15,000 cows, horses, sheep, goats, pigs, llamas, rabbits and other livestock.

There is a lot of manure.

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State officials estimate more than 250 tons of manure accumulate over the 12 days of the fair — the excremental equivalent of five sperm whales.

Every fourth night during the fair, the entire animal population departs and is replaced by a new set of livestock.

The evening of turnover is a hectic and busy time for Minnesota Dirt Works, the fair’s subcontractor for its dirtiest jobs.

During an evening turnover, enough straw-and-manure bedding to fill an Olympic-size swimming pool must be plowed out of the barns, loaded onto trucks and driven to a farm near Hastings.

The work starts around 5 p.m., when local athletic teams, booster clubs and church groups fundraise by picking out the human trash from the barns.

Soon after, Minnesota Dirt Works’ nine employees start using skid loaders to push the manure from the barns. Greg Harder, the fair’s livestock manager, said it’s “like pushing snow from a parking lot.”

The waste piles up on Stevens Street, towering 14 feet high and stretching half a block.

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“You look at it and you don’t think it’s going to go away,” said Dan Ames, the president of Minnesota Dirt Works.

But over the course of six hours, 13 full-size semi-trucks make a total of 60 hour-long trips to Hastings, where they dump their hauls on the side of a field.

The barns are then swept, disinfected and decorated with fresh straw to welcome a new batch of livestock.

“At 2 o’clock everything’s full, by 6 o’clock it looks like the day after Mardi Gras, by midnight everything’s clean, and by 2 in the morning the barns are getting filled back up again,” Harder said.

Mark Goodrich, the fair’s deputy manager in charge of livestock, said watching the turnover is a popular pastime.

“The city folks like seeing it happen,” he said. “They come down here to see the big boar. They come down to see trucks loaded up. Little kids love watching big tractors and big trucks and big horses. It’s taking city folks to the farm without having to go to the farm.”

And the manure?

It’s tested for nutrient levels, which determines how thick it should be spread as fertilizer. After it’s composted, it will be mixed with dirt across 1,000 acres of sweet corn and bean fields.

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“It helps the dirt stabilize itself,” Harder said. “Gives it some body, some organic body.”