4. The lurker: Pool lines, propane lines, landscape lighting and other ‘add-ons’
The danger:
So much gets buried in your yard after the “official” stuff is buried. Think about it: electrical wires to the sockets and lights on that shed or outbuilding. Pipes to heat the hot tub or pool. Here’s another biggie: Out in the country there might be a copper line that runs from the liquid propane fuel tank to the house. Strike that pipe just the wrong way and a spark could ignite the gas and cause an explosion. What’s worse, no regulations govern how deep that line has to be buried, says Dean Kranig, of Kranig Excavating and Landscaping in Eden, Wis.

If you’ve bought a house from someone else, you have no idea where this stuff is buried — or how deep.

“I’ve found that stuff as shallow as 3 inches and as deep as 2 feet,” Kranig says.

Avoiding trouble: Utility companies can’t help you this time; they don’t know where this stuff is, either. So what to do? 

Hire a “private locator,” Kranig says. For $100 to $150, a private locator will come out and do just that — find the other stuff that’s hidden beneath the sod.

Here’s another benefit of hiring a private company: It can locate stuff that a call to 811 won’t.

When you place a call to 811, the person who comes out to mark up your lawn doesn’t always mark every utility. (The laws vary by state.) You’ll be informed in writing what has been marked — and what hasn’t been marked.

BingParanoid? Get an underground shelter

Where Kranig lives in Wisconsin, for instance, “‘Digger’s Hotline’ doesn’t mark water lines, they don’t mark sewer lines,” he says.

If a call to the water company can’t get the job done for free, a private locator can track down the water line by clipping a test unit onto one part of the water line, Kranig says. “A good private locator will be able within about 18 inches of the line, where that line is, and also approximately how deep that line is.” (Your local 811 call center should be able to suggest some private locators, says Khrysanne Kerr, director of program development for the Common Ground Alliance.)

5. The lurker: Houses on shaky foundations
The Danger:
Many subdivisions are built on land that has been bulldozed flat and filled in to create level ground, covering ponds and filling in swales. Sometimes this is done lazily. Carter of Ask the Builder says he has seen piles of scrap wood and insulation buried by builders who are too lazy to rent a Dumpster. He once was an expert witness about a house that was literally cracking in half because it was built on a valley that was filled with trees and branches and then covered with dirt, “and they built the house on that, so the house was literally sinking.”

Avoiding trouble: If you suspect something fishy is going on underground — or if you’re about to buy a new home in a new area and want to be sure that the earth under your feet is solid — head to your local university, Carter says: The United States Geological Survey has produced both soil maps and topographical maps of where your house sits.

“Look and see what the land looked like before the earthmovers came,” Carter says.  Make sure you’re not buying a lot where they filled in a valley, he says, or “buying a lot where there used to be a pond.” With the soil maps, you can know what kind of soil to expect even before you turn a spade — and know if anything looks odd.

How to dig
If you need to dig in your yard, and you’ve called 811, don’t consider those colorful markings that the locator sprays — red for electrical, yellow for gas — an “X marks the spot” and start digging, says Browning of Duke Energy. Better to consider them places to avoid — and by a wide margin, she says.

Why?

“Guess what? They’re not always right,” Carter says. “They can be off by a couple of feet.” Laws vary by state, but contractors are often required to hand-dig (that is, use a shovel) within 18 inches on either side of where a pipe or line is thought to be. You should give them a wide berth, too.

“If it doesn’t make a difference where that tree goes that you want to plant, move it to the side two feet,” contractor Kranig says. “Why ask for trouble? If you accidentally hit that wire, you can accidentally kill yourself.”

If you absolutely must dig closer to a marking of any kind, here’s what to do:

  • Use a hand shovel and dig, slowly and carefully, until you’ve dug the hole you need or until you’ve found the utility.
  • Then dig around it with care. “It’s kind of like an archaeological dig. Take your time, digging.”
  • Don’t do anything aggressive. “Don’t stick a shovel in and jump on it,” Kranig says.  “A lot of people will take a pickaxe — they’ll say, ‘The ground is really hard.’ Well, that’s asking for it.”
  • Call your local 811 call center for assistance. The centers handle about 20 million calls annually and can give advice on digging near utility lines, says Kerr of the Common Ground Alliance.