The plan to get the Bay Area's only professional soccer team new digs hit a few snags thanks to secret underground bomb shelters buried on the stadium site.

The property across from the San Jose airport used to hold a tank manufacturer and until construction crews started digging, no one knew what was underground.

On Friday, NBC Bay Area got a firsthand look at the site on Coleman Avenue to see the problems that have been plaguing the project.

San Jose Earthquakes President Dave Kaval took us on a tour for an in person look at what has forced a delay of the grand opening. Kaval says demo crews encountered a surprise after trying to take down the old building that used to be home of the FMC factory.

“We thought it was a 6 inch concrete slab on the site but when we got down there we started finding stuff. They called them icebergs because they’d hit one and not even know how deep it was,” Kaval said.

In all crews unearthed 70 vaults, sub-vaults, and basements that had been used as bomb shelters. One was as large as an Olympic-sized swimming pool. Crews also found munitions, thankfully, they turned out not to be explosive.

A high water table in the area also created problems: one vault alone was holding so much water that it took 600 tons of rocks to get the water out. Kaval says they had no way of knowing what was underground.

“There wasn’t necessarily a record. We actually brought some old employees here from the actual factory out to get some more insight in terms of what was there,” Kaval said.

The City of San Jose told NBC Bay Area Friday that the planning department worked extensively with the Earthquakes organization to investigate the site beforehand, but said the FMC (Food Machinery Corporation) factory that was once a food machinery manufacturer was at the site too early for “as built” drawings.

That means no records to track what crews would find in the demolition process.

The San Jose Earthquakes boasts characters like the Bash Brothers, the Crow Ninja, and Wondo - who is one of the top scorers in all of Major League Soccer.

But if you walk around San Jose, you might be hard pressed to find anyone wearing the Earthquakes team logo.

There are hopes that the team will get a big fan boost once it gets a new stadium opens. It can hold 18,000 seats, which is almost twice the capacity of the one the team is using right now at Santa Clara University.

Chris Wondolowski, star player and top league scorer, said he and the team are excited for when the doors to the new stadium finally open for their loyal fans.

“It’s going to be great to get more fans out there and create even more of a buzz,” said Wondolowski. “And have it loud, have that home field advantage is always great.”