Utilities on Utilities: Investigating Overlapping Infrastructure

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Evan Mowbray

Utilities on Utilities: Investigating Overlapping Infrastructure

Over many years, the world has constantly changed with new construction projects, renovations, and infrastructure updates. We’re building newer, more modern structures in both new areas and existing sites, sometimes abandoning the old outdated systems that would provide utility services and installing new systems around them. This results in a constant complication of underground infrastructure that sometimes leads to utilities overlapping. This is more common in cities where decades of utility systems exist on top of each other, but it’s also common in suburbs and the country. Striking overlapping utilities could be dangerous for both systems. What do we do about making sure we don’t hit both existing infrastructure and abandoned infrastructure?

First thing’s first, how do you find out if two utilities are overlapping? Utility lines may cross over each other at a specific point along a path, running parallel or perpendicular. Gas, water, and electric lines can appear to lead in and out of the same place. Electromagnetic radar is a great way to determine if there’s overlapping lines. By connecting a radio transmitter to a specific utility line, you can get a stronger signal with radio detection to help differentiate between two different types of utilities. 

Our team was called out to examine the grounds of a school for a stormwater improvement project, where different types of utilities ran parallel and turned 90 degrees towards the main road from the entrance. There were already a few sewer lines that were found to travel under existing utilities, but it was easy to tell where those lines overlapped and how deep the sewer system ran based on inlets. The distance between the lines made it easy to differentiate between the lines up until a point. A neighbor near the entrance of the school accidentally hit one of the water lines while installing a fence. This resulted in a repair of the damaged water system and a utility adjustment to ensure the fence could be installed. This adjustment meant the water was moved to closer overlap the electric and communication utility lines. Radar detection can be a key in finding out where two utility lines overlap, but in order to understand how they overlap, we might need to dig deeper.

In addition to ground penetrating radar, vacuum excavation is a powerful tool for understanding how utility lines overlap. Using either air or water, we can uncover utilities without doing damage to the line compared to more conventional digging methods. Combined, ground penetrating radar and vacuum excavation make up the full service of subsurface utility engineering. By physically digging down to the utility, we can determine exactly how these things overlap along with the direction utilities are headed in. It’s also useful for unknown utilities; digging down to an unknown utility can determine what kind of utility or structure you’re working around. When utilities run close or over top of each other, such as the previously mentioned example, it’s often recommended to dig test holes for utilities to ensure a full understanding of what’s underneath.If you need a full understanding of your utilities, our team at Trinity Subsurface can help determine both the horizontal and vertical locations of your complex subsurface infrastructure. Visit the rest of our website to find out more information about the services we can provide for your next project!

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