Loose Neutral or Poor Ground?
Contact your power company and report an outage.

Specifically, a lost neutral.   This is a serious problem that needs to be fixed lickety-split.  

Your neutral is either gone or fading fast, and differential current is flowing through the neutral-ground bond, grounding electrode system, earth, to the transformer's ground and back to the transformer.  Dirt doesn't conduct electricity well enough to do that job, which is why the voltages are going out of balance. 

I bet the workers servicing the grounding electrode system were getting "zappity zap zap" while they were working on it. There should never be current flowing on ground wires.