Farmer with an auger attachment.
Cross country natural gas pipeline.
Never found farmer or tractor.
If you schmooze the guy up,In Iowa, all public utilies are required to belong to Iowa One Call. You call the 800 number (or 811) and you get a locate done withing 72 hours. You then have 48 hours to begin digging.
But they only locate public utility lines. Private lines must be located at the expense of the owner/builder.