Regular maintenance of a utility’s large-diameter pipe prevents emergency situations

June 23, 2020
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U.S. Submergent Technologies crew cleaning large diameter pipe in Tampa, Florida
USST Crew cleaning large diameter pipe in Tampa, FL.

Water and wastewater collection and treatment processes are largely out of sight, out of mind. Our society often takes this infrastructure for granted and is largely unaware of what’s happening below their feet, even though every person in this country uses it every day at home or at work.

Large-diameter pipe (LDP) is generally treated the same way throughout our industry; we don’t see it regularly, so we assume it is functioning properly. LDP infrastructure is primarily only cleaned or rehabilitated when issues arise, such as overflows or collapse that force attention. Once an emergency situation arises, utilities typically scramble to solve a large and complicated issue that they are unprepared to handle, exacerbated by the fact that large-diameter pipe is difficult to clean under flow while in service.

Managing Flow in Large vs Small Diameter Pipe

Large-diameter pipe is generally described as 24-inches in diameter or larger. Typically, utility systems have regular maintenance plans for smaller pipe systems 18-inches or smaller that involve a vacuum-only approach. Because of the smaller size of the pipes, cleaning this infrastructure is routine and often managed by the utilities themselves.

Flow in smaller pipes is significantly less than flow in large diameter pipes and is usually managed with vacuum technology. As an example, the capacity of a 6-inch diameter pipe compared with a 60-inch diameter pipe is 100 times greater, even though the difference in diameter is only 10 times larger. This reality is often missed because LDP comprises less than 5% of a collection system. These larger flows create challenges because of the amount of water that must be managed and possibly bypassed, when cleaning is required.

To clean large pipe systems under these conditions is challenging. Bypass is expensive and may not be a viable option. But regular maintenance of these larger systems is crucial to the health and preservation of collection infrastructure both short and long term.

One of the main roadblocks to cleaning LDP is managing flow. A simple vacuum cannot handle this type of project. A vacuum will produce little to no productivity when attempting to utilize it under heavy flow, compared to utilizing it with smaller diameter pipe under significantly less flow. The bottom line is if there is too much water, vacuum technology may not be as productive as when there is less water present.  Historically, when LDP needs to be cleaned, the pipes are either bypassed or blocked, sometimes using inflated devices, to block the water from flowing into the section of pipe being cleaned. The cleaning is then accomplished using confined space entry.

USST technology, equipment and skilled crew can clean LDP under full flow, while in service, and remove significant amounts of material at a high production rate, without the need for bypass or diverting flow. As one of the only cleaning processes in the nation that can accomplish this task, we stand ready to assist utilities to restore their collection system capacity. You can read more about USST’s large diameter pipe capabilities here.

USST’s technology can help determine if your large diameter pipes need cleaning

Regular maintenance of a utility’s large-diameter pipe will prevent emergency situations as well as maintain the designed capacity. Let us show you how it works by signing up for our Eyes in the Pipe Webinar to learn more about the technology USST is introducing and how to get visibility into your utility’s collection system. Reserve your spot today.

Have questions? Call (844) 765-7866 or email

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