A month later we are still digging in the backyard, taking out rock and piling up dirt.
We have now found the trench for the electrical line. In this trench, not far down from where we are digging, is a plastic conduit. Presumably the electrical supply lines are inside that conduit.
The conduit curves up as it gets to the house and vertically connects to our electrical meter and circuit breaker box.
In addition, we have found the cable and telephone lines. They were buried a couple inches into the dirt. The intent is to put them in a conduit like the electrical line.
In addition, we found another phone line that was left in the ground when we had a problem (last summer I believe) and they replaced the line with a new one.
We broke the water supply line once, just after we had the on/off valve switch replaced. We've put a temporary patch on to fix the break, until we can get to the point of dropping the entire water supply down to bedrock. At the moment we are supporting it in place.