Toolbox Talk: Underground Utilities

By Published On: March 22, 2022

Underground Utilities

A few decades ago we started burying utilities to keep them safe from the elements. Overhead power and telephone were proving difficult to maintain out in the weather, keeping trees clear, animals nesting or chewing on parts, theft of wires and components, it only made sense to hide them underground. The problem now is we can’t see them!

There is a free service throughout the US and Canada called the Common Ground Alliance. They provide a locating service to find and mark public utilities in the area of your project. In every state, you can call 811 and submit a request 2-3 days before you break ground. They also collect data in a report called DIRT (Damage Incident Reporting Tool) in 2020 there were 475,770 damages reported to underground utilities.

70% of damages come from 4 root causes

  1. No call was made to locate
  2. Excavator started digging without verifying marks
  3. Inaccurate marks from abandoned facility
  4. Excavator failed to maintain clearance after locating


What’s the Risk?

A standard electrical service to a house is two – 120v wires. Larger commercial buildings will have three lines. They are flexible wires with a thin black rubber sheathing, and that’s it there is no hard conduit or protective shield, just wires in the ground. Service lines are supposed to be at least 3’ below grade, but if there was something preventing that depth they don’t have to be.

Natural Gas main through a housing development are essentially a continuous 4” plastic pipe, with 1” pipes branching off to each home. In a perfect situation these lines are with the electrical service, but that’s not always the case. To locate a plastic line, they should have a tracer wire. Any time you put a shovel in the ground around your house, there is a risk of hitting a wire or pipe.

There are a few variables that might cause the locator service to miss-mark an underground wire. Because of that, the CGA requires the excavator (homeowner or contractor) to maintain at least 18” clearance from the marks. Within 18” you can only hand dig or “soft dig” (vacuum) until you locate and uncover the lines in question. You also should never start digging directly on the marks, you start to the side and dig toward the line, allowing the dirt to fall away from the lines to help avoid contact.

*Some states require up to 4 feet of clearance (Michigan for example)

What Do the Colors Mean?

Typically, utility companies will use the same colors throughout the state. An example of colored spray paint markings and flags are:

Orange – Telecommunication (phone/cable)

Yellow – Natural Gas

Red – Electricity

Blue – Water

Green – Sewer

The Monetary Risk

While utility services like electricity and gas can be very dangerous if you contact them, any of the services can cost thousands of dollars in damages or repairs. If not to save your health, do it to save your wallet. The DIRT report estimates in 2020 there was $30 Billion dollars in societal costs (that is indirect costs for facility damages, businesses unable to operate, medical bills, property damage, etc.) When a contractor is found at fault for utility damages, they are liable for these monetary damages.

The one call service is FREE and it can save your life, your business, and your reputation. Always make the call and wait for the clear before you dig.

Whats the Process

  1. Call 811 and set up flagging
  2. Wait 2-3 days for marking
  3. Check the site and online to see all utilities have “cleared”
  4. Respect the flags!
  5. Hand dig within the tolerance zone

Questions for you

  1. What is the service in your state called, have you ever called them?
  2. Would you run barefoot in the dark through a room full of legos? Or would you turn on the lights? This is the same concept, free risk reduction.
  3. Have you ever seen a shovel that contacted electric service?

Here are a few more Toolbox Talks related to digging: Trenching, Roll Over Protection, Diesel Exhaust

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