CHICAGO (STMW) — Police followed two would-be tree grate thieves to a recycling center on the West Side, where they found hundreds of city-owned tree and sewer grates, worth thousands of dollars.

Ald. Scott Waguespack (32nd), who went to the center with police, said the men were loitering near a tree in the 5000 block of West Pensacola Avenue on Thursday afternoon, which aroused police suspicion.

According to a complaint filed by the city’s Legal Department on Friday, police followed the men with the grate to Industrial Metal Enterprise at 901 N. Kilpatrick Ave. and watched them unload it.

Industrial Metal Enterprise buys, processes and sells industrial scrap metal nationwide, according to its website.

The complaint lists Ireneuez Kowalczyk and Janine Pawlus as the owners of Industrial Metal Eand Michelle Pawlus as manager. The complaint says the plant sells all metal received within 60 days.

But police found hundreds of pieces of metal city property at the facility, from rings that go inside sewers before they are built out to entire sets of tree grates, according to the complaint.

Everything was either stamped with the city’s name or the name of the foundry many city materials are sourced from.

Arena described “entire long dump trucks full of broken grates and broken city sewer caps, and just piles of tree grates” at the processing center.

“It’s astounding, it’s brazen,” he said.

Waguespack estimated the cost of the tree grates at up to $2,000 per set and the sewer grates near $500 each, though prices can change depending on the street they’re on.

On Thursday, police would say only that two people were arrested at the Kilpatrick address for theft, but no charges had been filed as of Friday afternoon.

Waguespack was in a meeting with Arena when Arena heard from his ward superintendent about the piles of city materials found at the processing center, so both aldermen drove to the site to see for themselves about 5 p.m. Thursday, Waguespack said.

At the site, they contacted the owner and city departments heads involved in the care of the streets, Waguespack said.

The owner of the processing center was trying to get two semi trucks loaded up and off the property while police were there, but officers blocked it from leaving, Waguespack said.

He said he’s noticed tree grates on Milwaukee Avenue and sewer caps missing on Elston Avenue, in addition to basically anything thieves can unscrew, including bike racks and parts of light posts.

The alderman said he watched footage submitted by residents of men hauling away tree grates late at night, though the license plates of their trucks was never visible.

He said the thefts have picked up in recent months, adding, “When they realized there was a place they could take it, then you saw grates disappearing at a lot higher rate.”

Arena said grates were taken from Milwaukee Avenue at the beginning of the summer, sometimes whole blocks at a time gone overnight. Arena said his office had filed numerous police reports, but there was no break until Thursday.

A spokesman from the city’s Legal Department said the site had been secured and a protective order prevents Industrial Metal Enterprise from selling or removing anything at the plant until it can be determined who the materials belong to.

According to the legal department’s complaint, the city’s Claims Manager asked Michelle Pawlus for permission to remove the city’s property from the Kilpatrick plant. Pawlus declined to answer.

Arena said he has paid for grate replacement out of his ward’s Menu money, adding the city should definitely seek restitution.

“That’s taxpayer dollars, and I want that money back,” he said.