How to Avoid Utility Lines When Digging in Your Yard

Trench-digging
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There can be any number of reasons why you might need to dig trenches or holes in your yard. And there can be just as many different types of utility pipes and wires running through your lawn at different depths, any one of which could lead to an expensive or dangerous mishap if you cut into a line while digging. Some reasons you might dig into your include:

  • Creating a garden pond
  • Planting a tree
  • Digging up the yard for a sewer trench
  • Digging fence post holes
  • Digging foundations for a deck, shed, or garage
  • Trenching a base for an intended retaining wall
  • Digging up parts of your lawn to install an irrigation system
  • Trenching your yard to add conduit for an exterior outlet or light

Utility lines that might run beneath your lawn unbeknownst to you include:

  • Electrical service wires
  • Cable TV or internet service wires
  • Telephone service wires
  • Sewer and water mains
  • Natural gas supply pipes

Avoiding these wires while digging can be harder than you think. As a home ages over the years and services are added to the house, trenches are dug and earth or sod are laid over the top, and the trench locations are quickly forgotten. When a home passes from one owner to another, the locations of these utility lines are rarely communicated to the new owner.

Further complicating the issue is the fact that the buried depth of these utilities can vary widely from area to area. In colder climates, sewer and water lines are typically deep in the ground below the winter frost line, and homeowners can freely dig shallow trenches for irrigation piping or low-voltage landscape lighting without much fear. The same homeowner who moves to a warm climate, though, can be startled to find that water and sewer pipes are quite shallow. And over the years, utilities are added and canceled, so that you may find that active telephone wires for landlines are still present in your yard, even though you long since transitioned to cell service for all your telephone needs. There are literally millions of miles of underground utility lines running beneath residential lawns in the U.S., and accidentally cutting into one of them can disrupt vital services or even cause a fatal accident.

Fortunately, there are effective ways to pinpoint the location of underground utility lines before you dig.

Start By Calling 811

In 2005, U.S. federal government made 8-1-1 the national number to call for alerting 71 different regional services that coordinate location activities for underground public utilities throughout the U.S. In most areas, the service is known as "Call Before You Dig," but it is known as "Dig Safe" in the New England region. The process works like this:

  1. Call 8-1-1 two or three days before you plan to dig (the lead time required varies from region to region). Your phone call will be routed to a central call center.
  2. Answer the dispatcher's questions regarding the nature of your planned digging project.
  3. The dispatcher will reach out and contact any public utilities in your area that might be affected by your digging project. In some cases, the actual location and marking will be done by private companies working under contract with the utility companies. In other instances, it will be employees of the utility company who do the work.
  4. Workers will visit your property and mark the ground with paint or flags to indicate the location of underground utility wires and pipes. Typical color coding in most areas:
    • White: Proposed excavation
    • Pink: Survey markings
    • Red: Electric
    • Yellow: Gas, oil, steam
    • Orange: Communications, alarms
    • Blue: Potable water
    • Purple: Reclaimed water, irrigation
    • Green: Sewer
  5. The markings are regarded as valid for about 1 month after they are marked, since the water-soluble paint can wash off over time. Wait until all utilities have been marked before you start digging. If your work will not begin for 30 days or more after the initial marking, you should call 8-1-1 again and have the marking repeated.

Limitations of 8-1-1

This free 8-1-1 coordination service will mark the location of utilities up to the point where the lines make their initial connection to the home or service meter. If these lines continue underground—such as from a house to a detached garage or shed—the 8-1-1 coordination service does not pinpoint the location of these secondary lines. These secondary lines are considered to be the owner's property, not the utility company's.

And 8-1-1 does not coordinate location services for any service wires or pipes that are not considered public utilities or which have been installed by private companies. Some of the underground lines that are not typically located by services coordinated by 8-1-1 include:

  • Security systems
  • Lawn irrigation systems
  • Line voltage (120-volt) landscape lighting systems
  • Low-voltage landscape lighting wires
  • Electrical conduits or underground cables running to pools and spas

Where private companies have installed underground pipes or cables, contact the company and ask for assistance in locating them. In some instances, you will be charged for this service.

Regional Services

In some areas there are aggregated services similar to the nationwide one—but on a smaller, regional scale. A few of the larger services:

Individual states often maintain web portals providing information on safe digging. They are easily found by typing "8-1-1 (state name)" in the internet search window.

These regional and state services are now generally coordinated with the national 8-1-1 service, but they may offer additional services. For example, the local aggregated services may let you schedule on-line, or they may put you in touch with private location services who, for an additional fee, can locate and mark any private utility lines on your property that are not covered by 8-1-1. These web sites also offer a wealth of information on how to plan and execute a safe excavation.

Tips for Digging

  • Keep your trenches or holes at least 18 inches away from 8-1-1 markings. The tools used to locate underground wires are not always precise, and 8-1-1 guidelines say that holes or trenches should be kept at least 18 inches away from either side of marked lines.
  • If you have installed underground wires or pipes yourself, consult your notes to determine their location. Most irrigation pipes and low-voltage cables will be fairly shallow, so digging a series of test holes by hand can help you locate them.
  • There are private location services who will inspect your property for a fee and locate any underground pipes, conduits, and wires. This is especially helpful for non-public utility lines that were installed by private companies.
  • Dig slowly. Irrigation lines and landscape lighting conduits and cables are not identified by 8-1-1 location services, so dig methodically and slowly, examining the excavation regularly for unexpected pipes and cables.