November 2022, Vol. 249, No. 11


Urban Pipeline Construction: Innovations Overcoming Density, Aging Infrastructure Issues

By Richard Nemec, P&GJ Contributing Editor, North America 

(P&GJ) — Under any congested urban street is more of the same crowding, but in the form of various utility conduits that support the commerce and other activity aboveground.

The markings are there for the trained eye appearing as different colored painted hashtags on the pavement: red marks electric lines, yellow is for natural gas pipelines, orange denotes communications, green marks sewer lines and blue is water pipes.   

Within this underground thicket could be a leaking 100-year-old gas main with a utility crew and engineers aboveground searching for its location.  

The job of maintaining pipelines in this urban mass has become more complex and global in scope. Each local operation is tied to a larger effort these days to mitigate against climate change by reducing methane emissions.   

Looking for faster, better, more effective ways to work in the densely populated environments has equipped pipeline operators and utilities with new sets of tools. Innovation is changing the makeup of jobs and mindsets within the energy field.  

Culminating in late 2020, the U.S. Pipeline Hazardous Materials and Safety Administration (PHMSA) and the Illinois-based Gas Technology Institute (GTI) evaluated and refined a technology for more than two years, enabling the 3-D location of “unlocatable” pipelines in a live flowing gas, real-time environment.  

The technology developed by the global utility underground management/detection firm Reduct was already in place when the PHMSA-GTI collaboration developed the application for urban pipeline operations/maintenance (O&M) work without shutting down the gas stream.

“This project enabled the deployment in a live gas main through a 90-degree fitting,” said Mike Adamo, GTI’s vice president for Operations, OTD. As a result, information now can be gathered that will help improve the accuracy of geospatial information systems (GIS) databases, Adamo noted, along with providing more accurate pipeline information for construction planning. It allows a geospatial probe to map existing buried pipelines, according to a Dec. 15, 2020, final joint report from GTI and PHMSA.  

There is now a commercial geospatial probe for mapping existing buried pipelines as a means of mitigating against third-party excavation damage and cross bores at the earliest stages, according to the GTI/PHMSA report, “Improved Tools to Locate Buried Pipe in Congested Undergrounds.”   

It concluded that the mapping technology will not interrupt service to downstream customers. “Additionally, a cloud-based data collection system will be created to quickly collect and store data that is easily accessible to utilities.”  

Both improved safety and planning should be a byproduct. The joint research produced an externally driven inner-pipe mapping probe that accurately routes underground pipelines within what GTI calls a 6-inch (152.4-mm) window of the pipe’s centerline.   

“The probe provides location data from inside the pipe, meaning that there is no reliance on acquiring location data from the surface to detail the coordinates of the pipe,” the GTI/PHMSA report notes.  

The increasing challenges of pipeline work in densely populated areas is spawning more innovation, driven by cost and climate change pressures.  

“A number of our members are using methane mitigation technology to avoid purging natural gas to the atmosphere during replacements and repairs,” said American Gas Association (AGA) spokesperson Jake Rubin. “A similar solution is in development for service lines, too.” Other AGA member utilities are enhancing their data collection and mapping with their accelerated main replacement programs, Rubin added.  

Utilities throughout the nation, stretching from Pacific Gas & Electric Co. (PG&E) in the west to Baltimore Gas and Electric (BG&E) in the east are piloting and installing patented, branded cross-compression processes, leak remediation technologies and various mapping approaches.   

In most cases, work in the urban areas these days requires extra training for utility and contractor crews who are applying special equipment, data and processes to O&M work under busy streets. The environmental payoff can be big as companies expand their emissions-free operations throughout their service territories.

In the fall of 2022, PG&E was already alerting its customers in the north San Francisco Bay suburb of Corte Madera of transmission pipeline testing and replacement work scheduled for 2023–24.   

On pipelines running parallel to Highway 101, PG&E plans replacements in 2023 and strength tests in 2024 on different sections of pipe on both sides and crossing the heavily trafficked north–south highway. The San Francisco-based combination utility told customers that it will perform “a strength test on our underground natural gas pipeline” to confirm the pipeline’s integrity and operating pressure.  

“During this test, we empty then fill the pipeline with water and pressurize it to a level higher than normal operating pressure,” according to the utility’s community safety notification. “We repair or replace sections of the pipeline that do not meet safety standards. During the test, you may see PG&E [and contractor] crews, vehicles and equipment. Our work should not interrupt customers’ gas service.”  

PG&E said it also plans to replace sections of the natural gas pipeline in Corte Madera, excavating around the existing underground pipeline and installing new pipe using “industry recognized and proven techniques.”   

Customers were reminded that construction would require PG&E trucks and other heavy equipment in the area. It further warned that crews may need to release natural gas from the pipeline by venting a pipeline.   

“As PG&E releases gas from the line, the smell of natural gas and the sound of venting may be noticeable,” the utility notice explains. “The natural gas released during venting will quickly dissipate into the atmosphere and will not be harmful. Customers in the area will be notified prior to any venting. PG&E encourages anyone who has concerns about natural gas odors in or around their home or business to call PG&E.”  

In the Rockies and Upper Midwest regions, Xcel Energy’s multistate gas utility network is focused on accelerating the reduction of methane emissions in its 36,000-mile (57,936-km) pipeline network because it is the most cost-effective path to net-zero solutions by 2050.   

This includes increasing the use of certified low-methane natural gas from its major suppliers and stepped-up vegetation management along pipeline routes as well as innovative approaches in congested urban settings.   

“We aim to operate a net-zero methane gas delivery system by 2030,” said Xcel CEO Bob Frenzel.  

On an accelerated basis, Xcel removes trees and brush along its approximately 2,400-mile (3,862-km) natural gas transmission rights-of-way to allow its crews the critical access needed to perform regular pipeline patrols, assessments and equipment mitigation. It also allows the company to comply with U.S. Department of Transportation regulations requiring regular monitoring to enhance safety.  

“Our work will occur on properties that have been identified as having incompatible vegetation around a pipeline,” Xcel told its customers. “Such vegetation includes trees, large shrubs and woody-stemmed plants that can interfere with the safe operation and maintenance of our pipelines, and whose roots also can damage the underground pipe.”  

Along with tightening up its pipeline network underground and clearing obstacles aboveground, Xcel has committed that by 2030 all its gas purchases will be produced with the lowest methane emissions rate possible.  

“As a conservative estimate, our current supply is purchased at approximately a 1% emissions rate per throughput,” according to an Xcel web report, equating to about 3 million short tons (mst) for both its natural gas and electric businesses. By 2030, the company aspires for the emissions intensity of gas purchases to be well below the national average of 0.25%.

CEO Frenzel has publicly acknowledged that what Xcel is attempting to do will be “extremely challenging.” For the near-term 2030 goals, the company most likely will have to purchase some offset credits. But he insists that the Xcel gas system is “a valuable, shared asset in which we’ve all invested over many decades, and we plan to continue using it for decades to come.”  

In the east, BG&E uses a company called ZEVAC (zero emissions vacuum and compression), which bills itself as a producer of products and technology, to apply gas emissions recovery and mitigate against methane seeping into the atmosphere. BG&E deploys reliable, proven and patented equipment in “most situations requiring purging/venting of gas,” including maintenance, repairs and abandonments.   

“We have used it mostly on main abandonments,” said Joe Reynolds, senior engineer for Gas Engineering. “As our crews become more comfortable using the ZEVAC, we hope to use it as much as possible.”  

ZEVAC officials said they can adapt to individual operator’s purchasing preferences with rental, sales and training options for its different-sized equipment.   

“We provide limited on-site service for demonstrations or emergencies and comprehensive training to self-perform routine maintenance with rented or purchased equipment,” ZEVAC officials said.   

There also is a network of trained ZEVAC contract crews. These are service companies with crews trained on the use of ZEVAC technology.  

BG&E’s Reynolds noted that ZEVAC is pneumatically powered with internal compressors that pull gas from one pipe and transfer it to a different pipe. Thus, it keeps the gas in the system and not in the atmosphere. Units used by BG&E are fairly large, Reynolds said, and are named Quad units because they have four internal compressors and are transported on a trailer in the urban settings. Smaller units also are available, such as ones used by some of BG&E’s sister companies in Delaware and Washington, DC.  

As with many gas operators, BG&E finds the ZEVAC units particularly useful in crowded urban areas. “There are many benefits to using [them] in those situations, namely reduction of greenhouse gas (GHG) emissions, cutting down on calls from customers complaining about gas odors and improved safety,” Reynolds said.  

Regarding leaks, BG&E has another technology from ULC Robotics, CISBOT, which is deployed to “stop gas leaks from the inside out.”  

It’s a robotic technology that works inside old cast iron mains to fix leaks and extend the life of the distribution pipelines without interrupting service or urban commerce. CISBOT repairs all the joints in a main by injecting an industry-proven anaerobic sealant. This process, as applied by BG&E, repairs existing leaks and prevents new leaks from forming. It supports the utility’s capital construction and emergency response.  

While internally fixing both jute and mechanical joints, CISBOT deploys a computer-controlled injection method with the ability to inject from multiple positions around each joint.   

“CISBOT is a less-expensive, less-disruptive approach to repairing large-diameter cast iron pipeline joints, and it was the right fit for [recent projects],” BG&E engineers noted.  

First, obstructions from the other pipes and wires eliminated the use of traditional excavation and encapsulations – there just wasn’t space for the traditional approach. Second, this section of pipeline featured joints positioned every 9 feet (2.7 meters), and CISBOT allowed BG&E to inspect and proactively repair multiple aging joints along the way.  

At Atlanta-based Southern Company, with gas operations spread around the South and Midwest, distribution crews are stepping up leak detection in congested urban areas while eliminating flaring and venting of gas with the use of compressed natural gas (CNG) equipment.  

Southern Company Gas, for example, is relying on systems that are both mobile and easy to deploy, according to Emeka Igwilo, vice president and chief of Operations Support.   

“The traditional leak detection picks up parts-per-million, but our mobile system gets parts-per-billion,” said Igwilo, focusing on business (urban area) districts. “Next year, we’re going to expand that to our entire footprint. This lets us know on a consistent basis where we have significant emissions on our system.”  

Southern has about 2,500 miles (4,023 km) of transmission pipelines within its four utilities, 75,000 miles (120,700 km) of distribution pipe and about 68,000 miles (109,435 km) of service lines. Most of the transmission assets are in rural – not urban – areas, Igwilo said. A few of the stations switching from transmission to distribution are in urban areas, but most are in less-congested areas.  

Southern’s approach focuses on three areas: people, processes and technology, Igwilo said. Training is intended for people. Southern is also finding new ways for processes to be more efficient and effective in urban areas. For technology, Southern emphasizes proven solutions.   

“We try to find partners that know what they are doing and that we can safely and reliably integrate into our system. The three areas are working in concert. We have really good operators who know the company is open to innovation,” he said.  

Igwilo said Southern is now identifying leaks at a higher rate than it did using the traditional leak detection approach. Another innovation is the use of CNG to avoid venting or flaring gas  during repairs and maintenance. Gas is stored as CNG and then returned to the pipeline in gaseous form.  

“It helps us to basically repurpose the gas and put it back in the system when the work is complete,” Igwilo said. “You can move it from site to site when it is needed for construction activity, and you can attach it to a trailer and move it around.”  

Southern focuses on the business districts, which are, by definition, congested, urban areas – “wall-to-wall concrete,” as Igwilo described them. It is the urban environment where operators encounter a lot of dense infrastructure with extremely limited rights-of-way and easements. “These areas are very, very hard to operate in,” Igwilo said.    

Southern also makes sure that when working in urban environments its crews are using best practices to mitigate against traffic and making the work “as minimally disruptive as possible,” Igwilo said.  

Training is a critical part of the newly heightened focus on work in congested areas. Contractors and utility operators alike are addressing this part of the conundrum and recognizing the current competitive job market raises the importance of the effort.   

“Finding the people who are willing to do this type of field work is a challenge in the current environment, and more so for the contractors,” Igwilo said. “We have relations with trade organizations, schools, etc., that create a pipeline for us, so we have a better chance than most to get the right people.”  

Southern Gas uses two models – contract crews, who are trained on the use of equipment, or utility crews. In any event, all crews are trained. “In compliance activity, you cannot operate the equipment unless your training is up to date.  

In support of its ongoing efforts, in 2021 Southern commissioned ICF Resources LLC to complete a study on decarbonization pathways for its gas operations. Company officials said the report in September 2021 is the “core component” of their ongoing value chain–based assessment, describing various portions of emissions coming from each asset class at the utility.   

“The ICF study is a prediction that we will use to perform direct validation measurements,” Igwilo said. “To the extent that urban areas have emissions, we will identify and mitigate them.”  

ICF presented Southern with four pathways, or strategies, for its ongoing operations, including one that would transition to total electrification, comparing costs and performance among the foursome.  

The analysis determined that the lowest cost and higher emissions reductions came from relying on natural gas technologies and increased use of renewable natural gas (RNG). ICF concluded that Southern Gas could keep its future costs “affordable by leveraging its existing gas networks with new and efficient technologies and RNG.”  

Southern CEO Kim Greene said the study confirmed that natural gas and a modernized delivery infrastructure are “foundational” to the company’s net zero emissions goals. “[ICF] identified gas-focused pathways that include a balanced approach to addressing how our utility operations and gas supply practices can be leveraged to achieve important climate goals,” Greene said.  

The initiatives under crowded urban streets take on added importance for achieving infrastructure improvements, advancing leak detection/repair, and enhancing measurement and reporting, along with the added reliance on RNG.  

Greene added that getting to net zero by 2050 also will require the intangible of reaching close coordination with local, state and federal regulators.  

Richard Nemec is P&GJ’s Los Angeles-based contributing editor. He can be reached at  

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