I was there as a "grantee" (i.e. Scientist) so I don't know much about the contractor side of it.

On the user-facing side, it seems to be a Microsoft-heavy place (we got active directory accounts, etc. and had to log into one of the Windows machines in the cluster to change our password).

My interaction with the IT people was mostly asking for port forwarding / static IP reservations for some some of our computers that needed to be accessible from up North, and for that they seemed to forward those requests to Denver (where the contractor HQ is).