Improve Pipeline Leak Detection and Mitigation

By Member Michael Graham

Every day more than 2.6 million miles of pipelines across the United States transport enormous volumes of natural gas and liquid petroleum that provide for the nation’s energy needs. These pipelines crisscross the country under our neighborhoods, homes, and businesses. While, statistically, pipelines are the safest method for energy transportation, the NTSB has investigated some accidents that demonstrate the need for improved pipeline leak detection and mitigation:

  • ​On February 23, 2018, a natural gas-fueled explosion at a house in Dallas, Texas, injured all five occupants, one of whom died. The house sustained major structural damage. Investigators located a through-wall crack in the 71-year-old natural gas main that served the residence and positive gas measurements leading from this crack to the residence. Investigators believe the pipeline was likely cracked in 1995 by accidental damage from mechanical excavation equipment. Leaked gas accumulated and eventually ignited from the gas main, which was damaged during a sewer replacement project 23 years earlier. Atmos Energy Corporation failed to detect the leak during an earlier investigation of two related natural gas incidents just two days before the February 23rd explosion.
  • On August 10, 2016, a 14-unit apartment building in Silver Spring, Maryland, partially collapsed due to a natural gas-fueled explosion and fire, which also heavily damaged an adjacent apartment building. Seven residents died and 65 were transported to the hospital, along with three firefighters, who were treated and released. The probable cause was the failure of an indoor mercury service regulator with an unconnected vent line, which allowed natural gas into the meter room where it accumulated and ignited.
  • On September 9, 2010, a 30-inch-diameter segment of an intrastate natural gas transmission pipeline, owned and operated by the Pacific Gas and Electric Company (PG&E), ruptured in a residential area in San Bruno, California. The rupture produced a crater about 72 feet long by 26 feet wide. The section of pipe that ruptured, which was about 28 feet long and weighed about 3,000 pounds, was found 100 feet south of the crater. PG&E estimated that 47.6 million standard cubic feet of natural gas was released, ignited, and resulted in a fire that destroyed 38 homes and damaged 70, killing eight people and injuring many more. Several people were evacuated from the area.

High Consequence Area Leaks

According to the Pipeline and Hazardous Materials Safety Administration (PHMSA), in the last five years, an estimated 1.05 million leaks have been repaired on gas distribution systems. While most pipeline leaks are minor, during the same time, there have been 827 leaks in high-consequence areas – segments of pipeline systems within more populated areas that pose the greatest threat to human life and property – on gas transmission systems, and an estimated 167 accidents on gas distribution and transmission systems.

Leak Detection and Mitigation

Pipelines reliably and efficiently transport the energy that provides heat and electricity for countless Americans. Ensuring the safe distribution and transmission is paramount. Pipeline leak-detection and mitigation tools are essential and can make the difference between a minor leak and a deadly explosion. The NTSB first identified the need for leak-detection and mitigation methods in natural gas transmission and distribution pipelines nearly 50 years ago, but PHMSA, the federal pipeline regulator, has yet to require operators to use these life-saving measures, and many operators have yet to act on their own.

Pipeline systems equipped with leak-detection systems and automatic shutoff valves, or remote‑control valves, can warn operators of an imminent accident and allow for quick mitigation. Also, placing gas service regulators outside buildings can prevent a gas-leak incident; yet, many older homes and multifamily structures still have regulators inside, which can trap accumulating gas and lead to an explosion. And finally, methane detection devices help mitigate the consequences of a natural gas leak by alerting the public, thereby minimizing exposure.

I encourage PHMSA, industry groups, pipeline operators, and the public to work together to ensure the continued safe transportation of our important energy resources.

What is the Solution?

The Role of The Regulator

PHMSA is trusted to act on behalf of citizens to enhance pipeline safety. To better protect public safety, the NTSB has called on PHMSA to:

  • Require all operators of natural-gas transmission and distribution pipelines to equip their supervisory control and data-acquisition systems with tools to help recognize leaks and pinpoint their location.
  • Require automatic shutoff valves or remote-control valves to be installed in high‑consequence areas and in class 3 and 4 locations.
  • Require that all new service regulators be installed outside occupied structures and that existing interior service regulators be relocated whenever the gas service line, meter, or regulator is replaced. Multifamily structures should be prioritized over single-family dwellings.
  • Require methane-detection systems in residential occupancies with gas service.

The Role of Industry Groups

Gas industry groups can also play a critical role in improving public safety. The NTSB urges industry groups to:

  • Revise the National Fuel Gas Code, National Fire Protection Association 54 to require methane-detection systems for all types of residential occupancies with gas service.
  • Develop additional guidance for gas distribution operators so they can safely respond to leaks, fires, explosions, and emergency calls.

Operators Can Enhance Safety Directly

Regardless of when—or if—PHMSA makes the NTSB’s recommended changes, pipeline operators can take steps now to mitigate gas pipeline risks. The NTSB recommends operators take the following action:

  • Review and update, as needed, their incident-reporting practices; policies and procedures for responding to leaks, fires, explosions, and emergency calls; and integrity management programs.
  • Equip supervisory control and data-acquisition systems with tools to assist in leak detection.
  • Install remote-closure and automatic-shutoff valves in high-consequence areas and class 3 and 4 locations.

These steps taken by the regulator, industry groups, and operators can reduce gas pipeline risks.

What You Can Do

The public also has an important role in preventing pipeline leaks and incidents.

The most common cause of a pipeline leak is accidental damage. If you are planting a tree, installing a fence, or digging on your property for any other reason, call 8-1-1 before you dig. The NTSB has investigated numerous accidents in which accidental damage played a role.

You can also greatly decrease the possibility of an undetected gas buildup by purchasing and properly installing a methane detector in your home. Early detection is critical.

As a reminder, if you ever smell gas, please evacuate the area, and contact 9-1-1 and the gas company.

Improve Pipeline Leak Detection and Mitigation is a safety item highlighted on the 2021-2022 Most Wanted List of Transportation Safety Improvements.

Learn more on

In this video, NTSB Member Michael Graham and HAZMAT Investigator Rachel Gunaratnam, talk about why leak-detection and mitigation tools are essential and can make the difference between a minor incident and a deadly explosion.

Atmos Energy Corporation Natural Gas-Fueled Explosion
Dallas, TX | February 2018

Building Explosion and Fire
Silver Spring, MD | August 2016

Pacific Gas and Electric Company Natural Gas Pipeline Rupture and Fire
San Bruno, CA | September 2010

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