The way I am reading this, it's not just the salt that's the danger. It sounds like the underground electric is becoming exposed to the weather and the electricity then travels through the water and onto the sidewalks, etc. Anything that accelerates the breakdown of concrete/asphalt (salt, time, other chemicals, traffic, freeze-thaw cycles of water, etc.) would present the same risks when compounded with the underground electric. It's just like a downed line above ground, except that those we can see and avoid.

DugansDad, do you have any underground electricity in your part of Montana? We don't have any in my part of Virginia, so all I have to watch for (electricity-wise anyway) are downed lines and exposed wires around my home.