The question of who will pay for about $15 million in disputed construction costs for the U.S. Bank Stadium is headed to mediation.

The Minnesota Sports Facilities Authority, which is overseeing the construction of the $1.1 billion Vikings stadium on behalf of the public, said M.A. Mortenson Co. has made a formal application for mediation over $15 million in disputed costs.

The Minneapolis-based contractor also filed for a right to proceed with arbitration if the mediation fails.

Authority officials, in a statement released Thursday, said that “while there has been continuous willingness to discuss these disputed costs, we have not yet been able to reach agreement.”

Taxpayers already are covering $500 million of the stadium’s cost.

Initially, the Vikings were covering $477 million, but since construction began, team owners have repeatedly increased their contribution. To date, owners Mark and Zygi Wilf have put an additional $95 million into the project.

The 66,000-seat stadium set to open next summer.

Staff report