Like above posters stated if you called (here it is called "call before you dig") and had all utilities marked you are off the hook. If not you have to pony up. A couple years back a buddy and I were putting a new electrical service in for his sister. Drove a 1/2" ground rod straight through the middle of a 3/4" gas line. I got lucky for one that I am still standing. When the utility came out first thing they did after shutting off the gas they called the utility locators. The locator told us it is law before breaking the surface of the earth to call and have utilities marked. $800 bill if I remember correctly.