Sewer Line Safety

Sewer Line Safety

What is a cross-bore?

Many utilities use trenchless technology to install underground lines. Trenchless technology basically consists of construction methodologies such as directional boring, moling, horizontal auger boring, and other methods for the installation of pipelines and cables below the ground with minimal excavation. This proven construction practice provides an alternative to open trenching and helps reduce road closures, minimizes restoration costs, and allows for safe and efficient utility construction in established neighborhoods or urban areas.

Prior to any construction, utilities and contractors are required to call 811 and request the marking of all utility lines in the area. Sewer lines are sometimes not marked or marked incorrectly, leaving the potential for natural gas lines to be bored through the sewer lines (“cross-bore”). A cross-bore can go undetected for months or even years. Eventually, if a sewer backup develops, a plumber is called to remove the blockage. Plumbers often use a mechanical rotary device to remove a blockage from a clogged sewer line. This practice can damage the utility line and create an unsafe situation allowing natural gas to migrate into the sewer system and even into homes and buildings. 

Columbia’s Sewer Line Safety Program

As Columbia continues with its enhanced focus on pipeline safety, the Company identified the need for a sewer line safety program to isolate and correct cross-bore situations. Columbia and its contractor will partner with local municipalities to inspect the sewer lines (service laterals, main, and storm) and take any necessary action.

Hydromax logo

Hydromax is our authorized contractor for the sewer line safety program in Virginia. You may receive phone calls from them to schedule an appointment to do some inspections or other work for the program.

Nonmetallic Utility Line Installations

Effective in 2002, Virginia law requires that any nonmetallic utility lines are installed in a manner so that they are locatable. Operators of sewer lines are required to mark their facilities according to the law when they receive notice of an excavation from VA811.

To learn more about Virginia’s Underground Damage Prevention Act, commonly known as the “Miss Utility Law,” log on to

If you have further questions, please contact Karl Brack, Director of Communications and Community Relations at 1-804-768-6410 or

Safety Tips

  • Call 811 before you clear.
  • Become familiar with the color coding of utility markings.
  • If the markings from existing underground utility lines cross the path of the sewer line, it may be a cross-bore that is causing the blockage.
  • Be alert to any unusual conditions, including:
    • Hissing sounds
    • Natural gas odor (rotten eggs)
    • Blowing dirt
    • Bubbling water (in a sink, toilet, or other area where water collects)
  • If you reasonably suspect or determine the blockage is caused by a cross-bore:
    • Do not attempt to clear the blockage with a mechanical device.
    • Contact and get help from the utility provider(s) that may be involved.
    • Hand or soft dig in the area where the blockage or the cross-bore may exist.
  • If a cross-bore is discovered:
    • Stop all work.
    • From a safe place, contact the utility operator involved if not already on site.
    • If you suspect a natural gas leak by smelling, seeing, or hearing gas escaping:
      • Leave the area immediately, and warn others to leave or stay away from the area.
      • From a safe place, call 911 and contact the gas company for the area.
      • Remain outside until the gas company can send someone to inspect the area.
      • Do not operate electrical equipment or anything or anything that could cause a spark, including phones, lights, appliances, doorbells, flashlights, tools, etc.
      • Do not try to find the leak yourself or operate any pipeline valves.
      • Do not proceed with your work until the utility informs you it is safe to do so.

Call 811 Before You Dig

VA811 is a free service for a Virginia residents. State law requires those planning to dig to call 811 at least three working days before the start of the project so all underground utility lines, including natural gas pipelines can be marked.

Damage from digging is the #1 cause of underground natural gas leaks. To avoid hitting a natural gas line:

  • Always call 811 three days before you dig.
  • Columbia Gas representatives will survey the land and leave marks corresponding to the approximate horizontal location of underground natural gas lines to within two feet of either side of the marks.
  • Dig with CARE around natural gas underground lines.
    • Dig with CARE means:
      • Call 811 before you dig.
      • Allow required time for marking.
      • Respect the marks.
      • Excavate carefully.