What's Below the Denver Airport?

Anons. Last year I spoke with someone I know and trust that is a member of the Denver Airport underground club. Here's what they told me.

There is massive complex underneath the airport that is built for a number of people to survive a major event. The complex has its own water and power supply as well as enough food to last about 25 years.

The list of members is limited and cost millions to become a member.

They told me that they entered the Denver airport and were directed to an elevator/entrance that was not labeled. Biometrics were taken to be used for future access.

The elevator took them down into a massive tunnel system where military type trucks and equipment were operating as well as workers in uniform. Like military but not.

They were directed to get on a small trolly/train that went for miles through tunnel systems. Once the trolly stopped they entered into a large imax like theater where they were presented an onboarding video about the complex.

Those are some of the details I remember and I have no reason not to believe this person.