We had a visit from an engineer from the Wellington City Council. They think there's a water leak under our driveway, which is dark concrete with a nice pattern pressed into it. Apparently the council just find or suspect the problem, we have to fix it. We'll get a letter some time about it, for now that's all we know.

The council guy says it's sometimes / usually earthquakes that cause the problem, but there's usually no way to prove it.

Does anyone have any information about:

 

1. How to find the problem, without digging up an entire driveway? The council guy had headphones and some kind of microphone, but couldn't pinpoint where the leak is.
2. Fixing a patterned concrete driveway without completely ruining it? For example, can someone with a big saw cut out the area where the leak is, then have it put back somehow?
3. I assume home owners insurance doesn't cover this sort of thing? I know it doesn't cover gradual damage to the house, but we don't have any of that, it's a leak.

It cost me about $20K to redo the driveway 5 years ago :(

Update: this is done and solved. See the answer for what we did.