I was a utility locator some years ago. What has been said above is completely true. The utility company (Century Link, Comcast, Xcel, etc.) own the cables or pipes up to and including the meter. It is their responsibilty to have the locates performed within 3 days after you call at no charge to you.

If they need into your backyard or through a fence, make sure it's unlocked, and you don't have dogs outside, or be home when they do he work. If the gate is locked, or dogs are present, they won't do the locate. I've been bit once, and trapped in a backyard due to dogs. And I refused to jump a fence to do the locate.

I'm not sure who does the locating where you live, it might be USIC, formerly SafeSite. If you do have private utilities in your yard (wired walkway lighting, underground power to an outbuilding, etc.) they can locate that as well, for a fee. I did private locates fairly often.

Also, it will help you later to bury a tracer wire with your new sprinkler system that the locating transmitter can clamp to. Just in case more digging is needed. Or draw up good blueprints of where it is buried. Use distance from sidewalk, tree, house wall, driveway, etc.