Upon activation you receive the Radio Signal Echo Foxtrot in Morse. It is one of nine drainage chambers broadcasting such a signal. Just east of the tower is the source, a Sealed Cistern just over the cliff face. Check your local map.
There is no clue as to the story of the deceased occupant, but it would seem that he or she took shelter in the drainage chamber when the bombs fell. When the walls crumbled and partially caved in, the occupant was buried alive, with only the upper torso and head protruding from the rubble.
There is a red "X" under the ground you can only see using no clipping mode (enter tcl in the console), similar to the other sealed cistern at WKML Broadcast Station.
Again when using the console command 'tcl' players can see that it is not in fact a drainage chamber but instead a possible escape route from train tunnels, there are two train tunnel segments which run parallel to the sealed cistern.