March 2019 Vol. 74 No. 3


Gas Distribution Replacement Work Continues Strong Pace

Michael Reed - Contributing Editor

As recently as 2017, the federal Department of Transportation (DOT) estimated 30,000 miles of cast-iron pipe still carried gas in the United States, with the highest percentage of these mains located in older eastern cities such as New York City, Philadelphia, Boston, Baltimore and Washington, D.C.

Further DOT data indicate that replacement work, while steady, is far from complete. In 2017, there were still 26,060 miles of wrought-and cast-iron gas distribution lines in service in the U.S., down from 39,342 miles since 2005, a decrease of about one-third.

About 97 percent of natural gas distribution pipelines in the U.S. were made of plastic or steel at the end of 2017, according to the DOT. The remaining 3 percent is mostly iron pipe.

The 2017 American Gas Association (AGA) Playbook reported during the past decade local distribution companies (LDCs) have installed updated plastic piping at a rate exceeding 30,000 miles per year.

With that in mind, these summaries show there is still a large volume of work to be done for decades through multibillion-dollar infrastructure replacement programs.

East a hotbed

Baltimore Gas & Electric (BGE) replaced about 45 miles of gas mains in 2017 and plans to complete a similar amount of replacements this year. BGE has addressed nearly 12,000 service pipes and risers during the past two years of its program.

BGE accelerated the pace of replacement following passage of Maryland’s STRIDE law in 2013 and the Maryland Public Service Commission’s approval of BGE’s accelerated plan in March 2014. STRIDE allows gas utilities to re- cover some of the costs of pipeline modernization as work is being done, making it possible to replace more aging infrastructure sooner. BGE invested about $55 million in 2014, $90 million in 2015, and projected 2016 investment was $113 million.

Con Edison continues to replace an average of 65 miles of cast-iron and unprotected steel gas mains each year and looks to continue at that rate for at least another 20 years. In fact, the company has proposing bumping its goal up to 100 miles a year.

PSE&G, which has more cast-iron pipes in its system than any other utility in the nation, remained busy in 2018. Of the system’s 18,000 miles, about 3,900 miles of mains are cast-iron, according to company records. The utility is on pace to replace 510 miles of aging cast-iron and unprotected steel gas lines by the end of the year under a program approved in 2015 by the New Jersey Board of Public Utilities. Completing the entire job is expected to take about 25 years.

National Grid is nearing completion of a two-year program to replace about 100 miles of aging steel and cast-iron mains across eastern and central New York state at a cost the company places at about $1 million per mile.

National Grid’s overall effort will likely take another 20 years as the company removes pipe, some of it dating back to the 1800s, replacing it with high-density plastic pipe.

In Boston, National Grid accelerate the number of miles of older mains it is upgrading and plans to replace over 400 miles of the remaining cast-iron, wrought-iron and unclad steel pipe in that system over the next 20 years.

More east work

PECO Energy serves 500,000 gas customers in southeastern Pennsylvania, about 90 percent of whom are residential, increased its main replacement pace from 14 miles to 30 miles per year in 2017 and has carried on at that pace. At the same time, the company increased its rate of bare-steel service replacement from 1,800 to 4,000 services in 2015.

PECO’s long-term infrastructure improvement plan was approved by the state’s PUC in May 2013, with the 10-year initiative boosting its projected capital investment in the modernization effort by $20 million a year. PECO plans to have all cast-iron and bare-steel mains replaced by 2035.

UGI Utilities, which has 600,000 customers primarily in eastern and central Pennsylvania, has 90 percent of its 12,000 miles of pipeline already constructed of modern contemporary material. That still leaves over 1,000 miles of bare steel and 300 miles of cast-iron infrastructure to replace.

The company expects to have all cast-iron gone by February 2027 with all bare-steel pipe replaced by 2041. The $1.2 billion replacement program, which began in February 2012, is on pace to update 65 miles of pipeline in 2018.

Washington Gas continues to replace about 15,950 miles of mains and over 230,000 gas services as part of its accelerated replacement program in Virginia, Maryland and the District of Columbia. The projects have been underway three years and will continue, depending on the location, from 15–40 years.

The company will spend $520 million over the next four years on infrastructure replacement projects, or an average of $130 million per year.


Avista Utilities, headquartered in Spokane, Wash., serves eastern Washington, northern Idaho and portions of southern and eastern Oregon. As is common in the western states, the company has never had cast-iron in its system, but still maintains a 20-year program to replace 700 miles of plastic main piping and install transition tubing at about 16,000 steel tees.

Pacific Gas and Electric Company (PG&E), which serves most of the northern two-thirds of California, replaced all system-wide cast-iron pipeline ahead of its 2014 year-end goal. Since then, it has focused on eliminating all pre-1940 steel pipe, replacing about 30 miles a year.


Alagasco, north and central Alabama’s largest natural gas utility with 460,000 residential and retail customers, invested an average of $24 million each of the past five years to replace gas mains. As of early 2016, the company had about 1,250 miles of cast-iron and bare-steel mains still to replace.

CenterPoint Energy estimated it would spend over $2 billion on replacement and further upgrades to its system by the end of 2019 in northwest Louisiana alone. At the time, CenterPoint had 118 miles of cast-iron and 408 miles of bare-steel pipelines remaining in Louisiana and planned to remove over 1,700 miles of cast-iron pipes—90 percent of its entire system—and 2,116 miles of bare steel over the course of 30 years.

Memphis Light, Gas and Water (MLGW), which is the largest three-service provider in the United States, serves customers through-out Shelby County, Tenn. The company began replacing its 330 miles of cast-iron mains in 1992 as part of a $100 million program. MLGW expects to have removed all cast-iron from its system by 2021.

Memphis Light, Gas and Water expects to have all its cast-iron pipe removed by 2021. (Photo by MLGW)

TECO Peoples Gas is actively replacing all cast-iron and bare-steel distribution pipe in the Tampa area under a program it began in 2012. The company is spending about $8 million a year to accelerate its 10-year program, which replaces an average of 15 miles of cast-iron and 40 miles of bare-steel pipe each year.


Columbia Gas of Ohio began replacing lines in the city’s downtown area in June 2016 as part of a larger program to improve over 20,000 miles of its system during a 25-year period. In 2016, the company invested over $25 million in Columbus, benefiting 4,500 customers.

DTE Energy, based in Detroit, is three years into a five-year, $2.5 billion gas and electric infrastructure upgrade in which it plans to spend $1.4 billion for natural gas pipeline infrastructure that spans 20,000 square miles spread across the state.

Dominion East Ohio, based in Cleveland, started replacing over 6,000 feet of pipelines in Ravenna, Ohio, as part of a $1.53 million project last spring, targeting the eventual elimination all 1950s-era bare-steel pipe with coated steel pipe. The work is part of a $4 billion replacement project that began in 2008 and is expected to continue through 2033.

PUCO later approved an expansion of the work and authorized an increase in the annual program investment. The ruling will allow Dominion to increase spending by up to an additional 3 percent in the years 2019 through 2021.

Integrys Energy Group continues to replace what will be a total of 2,000 miles of cast-iron mains within its Peoples Gas Distribution system, with a large portion of the work taking place within Chicago. In addition to the pipe, 300,000 service pipes and related meters will be installed.

Metropolitan Utilities District of Omaha (Nebraska) continues to replace its cast-iron natural gas mains. The effort coincides with replacement of the city’s water mains. The district expects to have abandoned its remaining 387 miles of cast-iron gas mains by 2027. Over coming decades, the Omaha MUD will also abandon or rehabilitate over 1,200 miles of cast-iron water mains. The size of the pipe being replaced varies but most are smaller diameter mains, measuring 3–8 inches.

Vectren, with 570,000 natural gas customers in central and southern Indiana, continues to replace gas mains and service lines in 15 cities across the service area. The multi-year program has replaced an average of 55 miles of bare-steel and cast-iron pipe each year at a cost of $37 million.

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