NEW YORK (CBSNewYork) — It has been nine years since the city swapped parkland for parking lots so the Yankees could build a new stadium, and a CBS2 investigation that started a year ago has uncovered a big problem with that deal.

As CBS2’s Jessica Schneider reported, the new parks are contaminated.

Kids play in the shadow of Yankee Stadium, at the Yankee Pocket Parks — just a few blocks away on River Avenue. Most of their parents have no idea the property is contaminated.

“The first thing that goes through my mind — I’m never going into this park again,” said area father Cesar Trinidad.

Trinidad’s 6-year-old daughter, Kayce, has been coming to the park for most of her life. She was shocked.

“They should close it,” Trinidad said.

The city gave the Yankees more than 20 acres of prime parkland on which to build the team’s $1.3 billion new home. As part of the deal, the city built eight new parks and redeveloped several city-owned parking lots to make up for the lost parkland.

The city built a playground for children and a skate park on the new parkland sites. But the problem is that under both lots are abandoned, leaking gas tanks that caused the contamination.

Corrugated metal structures with smokestacks rising from the top can be seen tucked away next to the parks. They house decontamination units that work to sift through and clean all the pollution underground.

CBS2’s Schneider asked Joyce Hogi of the Bronx Council for Environmental Quality whether parents should be concerned.

“Of course, of course they should be concerned,” Hogi said. “But I think also a lot of parents are unaware of the dangers that exist there.”

But Department of Parks and Recreation officials said there are no such dangers from the contaminated groundwater.

“It doesn’t sound good, but again, there’s no exposure to the public here,” said Liam Kavanagh, First Deputy Commissioner at the Parks Department.

The Parks Department said the parks near Yankee Stadium are, in fact, safe. But if it is, Schneider asked, why even do the cleanup and spend all that taxpayer money?

“You want the sites to be as clean as possible,” Kavanagh replied.

CBS2 has learned the cleanup effort has been under way since 2009. CBS2 also uncovered the contracts between the city and the engineering firm doing the decontamination work, and found it has already cost taxpayers $410,000.

And the cleanup still isn’t complete.

Still, Kavanagh said he would let his kids play at the parks.

“Yes, I would,” he said. “And you know, we’ve been very open with the community about both the condition and the progress.”

But community leaders to whom CBS2 talked are still fuming about what they call a dirty deal.

“We’ve always thought that was a very uneven swap — very uneven,” Hogi said.

The Yankees organization declined to comment, telling CBS2 the cleanup project is the responsibility of the New York City Department of Parks and Recreation.

The Parks Department insists children are safe while the cleanup process is ongoing.