After hand digging in rockdirt for 400 feet or so, carefully 8 inches, I encounter the CATV cable - 2 inches deep!!!!!! At least I didn't hit the gas line or electric service.
I know where my utilities are. When I bought the house they were marked out so we could get the CATV installed. Even then I was careful just in case they were near the 8 inch mark. Never thought I'd have trouble at 2 inches.
It's free to get all lines marked. You never know what they did. Even then I hit my cable too at about 6 inches. Thankfully it was in poly pipe sheath. I cut through some old unmarked cable wires. I was like "what is that?".
I've seen them laying under freshly layed sod. We carry a roll of coax and splice kits in all our service and install vehicles. You ever want an upset client, cut off his T.V. and Internet!