The city and county of Denver has shut down its bidding process on an expansion of the Colorado Convention Center for alleged bid rigging on the $233-million project. The city was getting ready to interview the three finalists on the job when it uncovered the improprieties.

In a letter posted on the city’s website on Tuesday, Denver Mayor Michael Hancock wrote, “I was fully briefed by the City Attorney and her team yesterday. We believe this is a significant breach of the public trust and a willful violation of a competitive bidding process. We will never tolerate this type of behavior from our contractors and will continue to address this swiftly and aggressively.”

The mayor asked the district attorney’s office to investigate the process, which the city says was “irreparably compromised by non-city participants.” The city alleges that documents were improperly released to a contractor bidding on the project, that “improper discussions about the bidding process” took place and that project plans may have been altered.

The three finalists for the contract were Hensel Phelps Construction, PCL Construction and Mortenson. The city’s executive director of public works is requesting a review of Mortenson’s “prequalification status for bidding on future projects.”

The mayor said in his letter that Denver also will “seek legislation to enhance the scope of the city’s debarment ordinance.”

Mortenson officials would not comment on the city’s actions, but Maja Rosenquist, senior vice president at Mortenson, released a statement on Tuesday: “We’ve received a letter from the City and County of Denver concerning termination of the RFP for the Colorado Convention Center Expansion project. We take the issues raised by the City very seriously and are committed to addressing this matter thoroughly and appropriately. We are conducting our own review of our participation in the RFP process and will cooperate with any further inquiries by the City or the District Attorney’s Office.”

Meanwhile, the city has terminated its contract with development company Trammell Crow, which was being paid $9 million for project management on the convention center job. In response to the action, Trammell Crow released the following statement:

“The alleged actions in connection with the Colorado Convention Center project have in no way been authorized by Trammell Crow Company and are contrary to the firm’s values and longstanding business practices. We are cooperating fully with the City and are conducting our own internal investigation. We will take internal actions as the results of our investigation dictate, including appropriate disciplinary measures.”

Company representatives did not immediately respond to requests for an interview.

No Official Charges or Details Provided

The city did not offer details about the bid-rigging allegations nor have prosecutors charged or indicted any of the companies that may be involved.

Trammell Crow has been involved in some of the Denver area’s largest projects, including the revamp of the city’s Union Station, History Colorado Center and the construction of Denver Water’s $196-million headquarters complex, for which Mortenson is the general contractor.

Mortenson has worked on several large city projects lately, including the new Westin Hotel at Denver International Airport. It is leading construction of the Gaylord Rockies Hotel & Resort, a nearly $800-million private project near DIA, set to open on Dec. 18.