Cross Bore Safety

What are Cross Bores?

A cross bore occurs when one utility gets inadvertently installed through or damages another pre-existing utility. M.U.D. is concerned with situations where a natural gas pipe has been installed through a sewer lateral. A sewer lateral is the privately owned sewer pipe that connects a home or business to the city’s mainline sanitary sewer. The city’s mainline sanitary sewer is the large sewer pipe generally installed underneath the street.

Cross bores typically occur when a utility is installed using a trenchless installation method. Trenchless utility installations lead to cross bores because the construction personnel installing a new utility cannot see what is underground and therefore cannot avoid it.

M.U.D. prefers to install gas pipe using a trenchless installation method — called directional boring — because it limits the invasiveness of construction, especially in developed areas of the city. Directional boring involves digging a hole at the start of the pipe and one at the end. A directional boring machine then drills an underground hole between the two holes and pulls the entire pipe segment underground. In the past M.U.D. installed its gas pipe by digging a trench along the entire length of the pipe.

Directional boring is also safer for the residents in an area compared to having an open trench the entire length of the pipe. Directional boring is also quicker and more cost effective for our customer owners.


Inspection Program

M.U.D. partners with plumbing contractors to perform sewer lateral inspections for certain areas. These free safety inspections are to check for damage that may have occurred to the sewer pipe connecting your home to the mainline sanitary sewer, which is typically located under the street. Damage to this sewer pipe may have occurred during a previous underground natural gas pipe installation in the area. M.U.D. is proactively inspecting areas where this problem could have occurred.

A damaged sewer pipe could pose a safety risk to your home.
If a plumber uses mechanical cleaning equipment in the damaged sewer pipe, the equipment could sever the nearby natural gas pipe causing natural gas to leak into your home. Because this is a safety issue that could affect multiple homes, on April 6, 2011 our Board of Directors approved an amendment to our Gas Rules and Regulations that allows M.U.D. to shut off a customer’s gas and/or water service if we are unable to inspect that property’s sewer pipe.

These inspections take between 30 and 60 minutes. During the inspection, the contractor will insert a small camera into your sewer lateral and attempt to inspect the pipe between your house and the mainline sanitary sewer.

Frequently Asked Questions (FAQs)

  • Why are sewer laterals different than other utilities?

    Prior to directional boring, M.U.D.’s construction crews call in a utility to locate and identify all the utilities that will be crossed by the new gas pipe. The construction crews then dig holes to expose each of these utilities at the point they will be crossed so they can visually verify the new gas pipe does not damage the existing utility as the gas pipe gets installed. Sewer laterals are a problem because they are owned by each individual homeowner and thus not located during a standard utility locate. So M.U.D. does not know where each sewer lateral is and therefore cannot visually verify it has not been damaged.

  • Why is the issue of sewer laterals coming to light now?

    Generally, the city owned mainline sanitary sewer is installed very deep in the ground compared to the depth a gas pipe is installed. The previous thinking in the natural gas industry was the elevation difference was so great that there was a very low risk of damaging a sanitary sewer or sewer lateral. However, many sanitary sewers were installed years ago when standards were not as strict as they are today. Likewise, the standards for installing sewer laterals were not as stringent. Therefore, there are instances when the elevation difference is not nearly as great as what it would be by today’s standards.
  • Are cross bores just associated with the natural gas industry?

    No, this is a problem that occurs with any company that installs its utility using directional boring. Many utilities including natural gas, power (electricity), telecommunications, and fiber optics are installed throughout the Omaha area and the rest of the nation using directional boring.

  • How frequently do cross bores occur?

    Nationally, it is estimated there are two to three cross bores per mile of installed gas pipe. Based on the inspections performed over the past year, M.U.D. has seen quantities similar to the national average in Omaha.

  • Are cross bores a safety hazard?

    Cross bores are not an immediate safety hazard. The normal waste water passing through a sewer lateral will not harm a gas pipe. Depending on the location of the cross bore, it may cause a sewer lateral blockage over time. Cross bores can become dangerous if someone attempts to clear the blockage using mechanical cleaning equipment such as augers that can cause the gas pipe to become severed causing natural gas to leak from the pipe and can lead to a deadly explosion.

    A sewer lateral is generally installed in a downward slope from a home to the street. Because natural gas is lighter than air, it will go up when released to the atmosphere. If a natural gas pipe is severed inside a sewer lateral, the gas will try to rise which means it travels towards the home rather than into the mainline sanitary sewer.

  • What is M.U.D. doing about cross bores?

    At the beginning of 2011, M.U.D. began inspecting the sewer laterals of all properties in an area where we installed gas pipes using directional boring. M.U.D. construction crews are also placing pink warning tags on the front doors of all homes in areas where direction boring installations are being done. We also compiled a list of all the areas where we installed gas pipes using directional boring in the past. We are in the process of inspecting these areas as well; however it will take several years to complete all of the necessary inspections.

  • How is M.U.D. performing sewer lateral inspections?

    M.U.D. is currently using several contractors to visually inspect sewer laterals. One type of contractor inserts a small camera into a home’s sewer lateral and pushes the camera from the home to the city’s mainline sanitary sewer. The camera is typically inserted into the sewer lateral through a basement cleanout, rooftop vent pipe, or floor drain.

  • What should I do if a contractor contacts me regarding a sewer lateral inspection?

    M.U.D. partners with plumbing contractors to perform sewer lateral inspections. It is possible one of these contractors will call to schedule an inspection. These companies will also be placing information tags on homes where inspections are needed. Please remember, these inspections are free of charge so our contractors will not attempt to charge any residents or up sell any of their other services while doing work for M.U.D.

    If you have any questions or concerns when contacted by a contractor on behalf of M.U.D., immediately call us at 402.554.6666 prior to letting anyone inside your home.

  • How do I know if my sewer lateral has a blockage?

    A sewer lateral blockage has different characteristics than a standard drain blockage. A drain blockage will cause one drain to run slowly or not at all while other drains in a house flow freely. A drain blockage could also occur anywhere in a house. A sewer lateral blockage will cause multiple lower level drains to run slow or back up. Please note, this will be most apparent on the lowest level of the home and not on any levels above that.