Cutting Out the Risk

Utilities need to work together to eliminate cross bores and the associated dangers they present.

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Last month we presented several photographs to be coded. I would like to dedicate this entire article to one code in particular, the OBI code.

The Pipeline Assessment and Certification Program and Lateral Assessment and Certification Program manuals define the OBI Code as an “Object Intruding Through the Pipe Wall — typically third-party objects that have been inserted after the pipeline/sewer’s construction.” This code is used in pipelines and laterals to describe a condition within a pipe where another utility such as a gas line has penetrated the pipe, causing a very serious and potentially dangerous phenomenon known as a cross bore.

The Cross Bore Safety Association defines cross bores as “an intersection of an existing underground utility or underground structure by a second utility, resulting in direct contact between the transactions of the utilities that compromises the integrity of either utility or underground structure.” Damage caused by cross bores can be instantaneous, or can take weeks, months or years to manifest to the point where the damage is evident. Utilities such as electric, fiber optics or water mains that are accidently installed through sewer laterals and mainlines can cause fractured or broken sewer pipe, or even collapse.

When gas mains are installed through these sewers, they may lie dormant for 20 or 30 years until a sewer cleaner or plumber cleans the line, at which time the sparks from the cleaning tools reach, for example, a pressurized gas source, causing an explosion. Over the years, such explosions have destroyed property, caused many injuries, and cost several lives.

Gas companies around the country are using CCTV to inspect pipeline and lateral segments for objects intruding through pipe walls. Many sewer providers are also inspecting their laterals as part of a comprehensive system evaluation to eliminate extraneous flow into the system.

Regardless of the system owner’s responsibility for maintenance of the lateral once it leaves the mainline, or how the inspections are funded, the condition of the laterals in a system can provide valuable information about the operation of the collection system. The best of both worlds is when sewer and gas providers can work together to the benefit of each. Many municipalities throughout the country have worked together with gas companies to provide each with the information they need at a reduced cost.

In Cincinnati, the Department of Public Works has developed such a relationship with Duke Energy. By working together and using the common language of LACP, the gas company can investigate all defects coded OBI for potential cross bores, while the city can determine the condition of lateral pipes connected to their mainlines to make determinations related to I&I, potential operation and maintenance issues, or just to mark lines more accurately for future utility crossings.

“This arrangement has saved both utilities money,” says Jerry Weimer, supervisor of the Metropolitan Sewer District of Greater Cincinnati. “By sharing the cost and management, the program has found multiple cross bores, both gas and other utilities, preventing possible catastrophes.”

It is important that sewer providers work with gas companies to help eliminate cross bores while providing a higher level of service to their customers at a reduced cost. You can find more information about cross bores at

By working together, we will all win while promoting NASSCO’s mission to assure the continued acceptance and growth of trenchless technologies.

Ted DeBoda is executive director of NASSCO. He can be reached at


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