DENVER — The developers of Denver International Airport’s Great Hall renovation project are speaking out for the first time following the city’s termination of its contract with them.

Great Hall Partners was fired Tuesday over concerns about cost, the project’s timeline and safety.

The FOX31 Problem Solvers obtained hundreds of previously classified documents written by the developer to airport officials highlighting issues with the project.

In July, the developers complained about airport management:

“Not only does the owner continue to make substantial changes to the design at this late stage, but the owner’s failure to issue much-needed direction and support regarding these owner caused changes plagues the project,” a document states.

Great Hall also questioned DIA CEO Kim Day’s leadership, saying she was “rarely available to make a decision.”

A major issue repeatedly mentioned in the documents was concerns about concrete and whether it was stable enough to carry out designs.

Great Hall referred to it as “concrete cancer” and alleged airport officials covered up previously known information regarding the concrete.

“Had owner timely disclosed this information and its concerns about weak concrete[,] Developer could have [..] avoided months of delays and millions of dollars,” a document states.

Before being fired, Great Hall estimated the projected would cost $288 million more than expected and would not be completed until 2024.

The project was supposed to be complete in 2021.

Kim Day answered questions regarding whether she should be fired Tuesday.

“Certainly I am at will and the mayor could do that, but I think we are in agreement this is the right thing to do,” Day said about her future.

Day also addressed concerns about the concrete.

“We do not believe there is a concrete problem that impacts the Great Hall but we are doing testing to make sure,” she said.