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PSE&G Utilizes CISBOT to Remediate a Challenging Cast Iron Gas Main Leak

Project Overview

Union City, NJ is a suburb of New York City situated just a half mile from the Lincoln Tunnel, a key thoroughfare into Midtown Manhattan. PSE&G is the largest utility company in New Jersey—providing natural gas to 1.8 million customers as well as electricity to 2.2 million customers over a 2,600 square-mile corridor across the state.

When a leaking joint on a 20” diameter cast iron gas main operating at 15psig forms under a newly paved, 5-way intersection in Union City, PSE&G chose to utilize CISBOT robotic technology to address the leak and prevent new leaks from forming in the vicinity for years to come. The technology addressed the leak with no disruption of traffic in the intersection or gas service to customers.

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Union City, NJ

• 20” Cast Iron (15 psig)
• 89 Joints Remediated (1,070ft)
• 1 Excavation

• Addressed leak in intersection and protected main against future leaks
• Avoided large-scale excavation and roadway restoration
• Minimized disruption to the public


Traditional leak repair at the leak location would have been challenging, costly and disruptive. In addition to the 20” cast iron gas main being 8ft deep in the area, the intersection of John F. Kennedy Blvd and Bergen Turnpike is a heavy traffic corridor that hosts commuters, public transit routes as well as a consistent flow of emergency vehicles.

“Excavating over the leak would have resulted in multiple deep excavations as well as a requirement from Union City to re-pave and restore the entire intersection,” says Ryan V., Sr. Supervisor Gas Distribution at PSE&G. “Even after patching the leak, there would still be a risk of additional leaks forming in following years.”

The 20” gas main was also a feeder, helping move larger volumes of natural gas throughout the community. Challenges around taking the gas main out of service limited repair and restoration options since taking the main out of service was not possible.


To resolve the leak and prevent new leaks from forming along the gas main, PSE&G opted to utilize CISBOT Robotic Cast Iron Joint Sealing to remotely remediate the joints in this section of main.

With the robot’s ability to travel up to 700ft from the point of entry, PSE&G was able to identify a point of entry 150ft away from the leak to position the CISBOT launch site. While the leak was in Union City in an area that would be highly disruptive and challenging to get permit approvals, the launch site selected by PSE&G was in North Bergen, NJ which has less restrictive access requirements and would not require curb-to-curb restoration. The gas main was also not as deep in this area – further reducing excavation costs.

Before the pre-sealing inspection on December 5, 2023, GMI readings were taken nearby to monitor the leak and ensure there was no public risk. ULC’s field operations team began joint sealing the following week to begin addressing the immediate leak area. Additional GMI readings were taken after the sealing process which showed zero gas readings. PSE&G plans to continue monitoring the area.

CISBOT was able to internally remediate 89 joints over a period of four working weeks to resolve the active leak and prevent new leaks from forming along the 1,070 ft section of gas main.

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ULC Technologies’ ability to deliver robotic internal cast iron joint remediation in live mains meant the project could be delivered in colder months when gas demand is increased. This allowed PSE&G to resolve the issue without having to wait until the spring. The solution is also providing a reactive and proactive approach by fixing any existing leaks on the gas main and preventing new leaks from forming for many years.


“CISBOT sealed 89 joints over approximately four working weeks to address the active leak and protect against future leaks. This technology helped us significantly reduce costs and disruption to the public and was remarkably easy to coordinate and set up. This was not only a success for PSE&G, but it was also a win for the whole community.”

Ryan V., Senior Supervisor, PSE&G


To learn more about CISBOT visit our web page or contact us.

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