If you’re using utility locating systems before hand digging or vacuum excavating around One Call marks, you’re ahead of the curve. The majority of contractors don’t use utility locating devices, says Dave Gasmovic, president of McLaughlin Boring Systems. If you are one of those contractors, you could save yourself a lot of time and perhaps grief by pinpointing the exact location of utilities before exposing them.
Safety zones around One Call marks vary by state, but are usually 2 feet to either side of the mark, which may be off several inches. “If you’re going to use a vacuum excavator that excavates a 6-inch hole and you have 4 feet you might have to vacuum, that’s a lot of lost time,” Gasmovic says.
The two most common types of utility locating systems are ground-penetrating radar and electromagnetic, or radio frequency, devices. While radar can give you a picture of everything underground, electromagnetic locators trace a specific utility.
Determining which type of locator to use, or if you need to use both types, can be tricky. The decision depends on factors ranging from soil type to utility depth to how crowded the underground environment is.
“I like to stress that in this day and age it’s a combination of approaches that solves a problem,” says Matt Wolf, president of Mala GeoScience. “No one piece of equipment is going to give all the answers underground, and at some point, none of the technology gives you the answers you need. Sometimes they all fail.” And at that point you have to turn to hand digging or vacuum excavation.
Radar vs. radio-frequency locating
The experts we talked to point out that you have to be aware of the different restrictions that go along with radar and radio-frequency systems so you’ll know when you should turn to another locating technique.
“If someone shows up with just one type of equipment to do locating work, they’re not getting as much of the story as they could possibly get,” says Ronald LaBarca, president of US Radar. “Using both types is one more level of protection. It’s like getting a second opinion from a doctor.”
