That is the strangest setup I have ever seen. Everything indicates that it's underground.
Here in Florida you dig 3 ft down. You hit water so nothing's ever underground but maybe they can get away with it up there.
The sheet metal structure comes off the tower is the "cable tray" aka "Ice bridge" that takes the antennas cables to the main equipment, switch gear, and batteries.
There has to be a door or hatch where they can go down into the equipment room.
Probably fed off two split phase or three-phase. I see all the light poles in the parking lot so there's power.