MINNEAPOLIS (WCCO) — Just days after touting the Vikings stadium as 90 percent complete, the contractors reveal millions of dollars worth of repairs are now needed on U.S. Bank Stadium.

Leaks in the snow gutter system are causing water to collect behind the siding. The billion-dollar sports arena is specially designed to move winter snow down a steep roof into heated snow gutters where it melts, but stadium builders recently uncovered a serious glitch.

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“We discovered, late fall, was that there was water that was penetrating the exterior skin of this wall, and was accumulating inside the wall cavity,” said John Wood, Vice President of Mortenson Consturction.

Water is leaking on the outside wall of the snow gutters, which are shaped like a giant continuous bathtub around the top of the facility. There’s no water damage inside, but Wood says fixing the problem outside is a major undertaking.

“It will be very visible to folks,” he said. “People will be seeing us taking the metal panels off the building, doing the repairs behind it, and then replacing them.”

Workers will remove 30 percent of the stadium panels circling the outside top of the facility, and install new vapor barriers, but first they’ll have to take down the massive U.S. Bank Stadium logos on the north and south sides.

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It’s a serious setback, but Wood says it’s fixable.

“It’s not going to delay the completion of the project,” he said. “We’ve got enough time to do the repair between now and opening day.”

Mortenson Construction estimates the repairs will take 90 days and cost $3 million to $4 million, paid for by the builders and designers.

In a separate development, the Minnesota Sports Facilities Authority tentatively agreed to pay Mortenson $16 million for cost overruns on the $1 billion facility for expected cost overruns, which could go as high as $29 million.

In a statement, Sports Authority Chair Michele Kelm Helgen said:

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“The agreement reached calls for the Authority to contribute $16.25M toward a settlement. I want to be clear, no additional state/taxpayer money is needed for this settlement. Current project funds along with an additional contribution from the Vikings will cover this.”