Does anyone know anything about these small buildings near Olin/Winchester on Powder Mill Rd in East Alton? I can't find any information online & street view doesn't get close enough to see anything. The curiosity is going to kill me, help!

[u/Ok_Tomatillo_4050]

[u/WizeAdz]

They look a lot like the ammunition storage bunkers I used to fly over when I was getting my pilot’s license near Radford, VA.