In article ,
"Al Schmidt" wrote:

How do I find underground wires (110V, water sprinkler valves,...)?

Call your local underground utility locating service.

In addition to making the arrangements to have your PUBLIC lines located, they
may be able to suggest a contractor that will locate PRIVATE lines.

In the past, I have, as a courtesy, located ONE private line (or two) for a
good customer. These days, locators are so very pressed for time that such
freebies are probably nonexistent.

Plastic water lines (no metal) CANNOT be located by COMMON locators.
Nonmetallic lines (gas, etc) are usually placed along with a 14-12-gauge
locating WIRE in the same trench. Lawn sprinkler companies usually don't
bother to place such wires. Good luck!
--

JR