Natural gas utilities with high rates of leak repairs are aggressively pursuing pipeline system upgrades to eliminate aging and leak-prone materials.
For the third consecutive year, Consolidated Edison Co. of New York Inc. had the highest ratio of leaks repaired per mile in 2016 among gas utilities with at least 5,000 miles of distribution main and service lines, according to an S&P Global Market Intelligence analysis of data from the U.S. Pipeline and Hazardous Materials Safety Administration, or PHMSA. Corrosion was the most common cause of leaks, representing 47.3% of the leaks repaired on ConEd's system, the data showed.
A fatal March 2014 gas explosion prompted the company to refocus its safety priorities, including increasing its focus on leak detection and repairs. Now, ConEd surveys its service area for leaks 13 times annually, and the company repairs leaks — including certain nonhazardous leaks — within 25 days, on average, according to ConEd spokesman Allan Drury.
As a result, the company has cut its leak backlog by 68% over 2014 to 2016, ending 2016 with 239 leaks remaining, according to Drury. The utility has been trying to drive up public awareness about the importance of reporting gas odors, and the campaign appears to have worked as the number of leak calls has "increased significantly," Drury said.
The Consolidated Edison Inc. subsidiary spends about $50 million annually on leak repairs. ConEd is also working to speed up the process of replacing its aging infrastructure with modern materials.
"We have made the replacement of main a stronger focus in our capital expenditure program with a significant emphasis on replacing cast iron and unprotected steel distribution mains," Drury said in a recent email.
The company expects to replace about 1,870 miles of main during a 20-year program, including all of its cast-iron and unprotected steel gas mains that are 12-inch diameter pipes and smaller by 2036. The new target expands on a previous program aimed at replacing those materials on 8-inch diameter pipes.
Pipeline replacement in ConEd's service territory can be expensive and challenging given the population density of New York City. In less developed surrounding areas, such as Westchester, N.Y., for example, main replacement costs about $500 per foot. In Manhattan, that figure jumps to $2,000 per foot. In 2017, ConEd will replace 80 miles of main, although the utility has plans to ramp up to 100 miles annually by 2021. About 10 miles per year are replaced due to new or worsening leaks, Drury said.
Baltimore Gas and Electric Co., fourth among the top 10 utilities with the most leaks repaired per mile in 2016, is also chipping away at replacing its aging infrastructure. The company is upgrading the system from older to more modern material that is less leak-prone and also eliminating some of the pipe leaks in the process.
As the oldest gas utility in North America, BGE has spent years modernizing its 13,570-mile system. Nearly 56% of the company's distribution mains and service lines were plastic in 2016. Nearly 9% of the system was iron and more than 6% was bare steel without cathodic protection in 2016, PHMSA data showed. Cathodic protection on pipelines uses direct current to combat the electrochemical process that corrodes steel pipe material.
"BGE has been replacing aged gas infrastructure for a number of years," company spokesman Justin Mulcahy said in a recent email. "Under our Strategic Infrastructure Development and Enhancement program (STRIDE), first approved by state regulators in 2014, all aged infrastructure replacements are to be completed within 30 years, significantly accelerating the pace of replacement over pre-STRIDE levels."
In 2013, 9.8% of BGE's system was iron and 7.4% was unprotected bare steel. Another 4.8% was coated steel that lacks cathodic protection, while 1.2% was cathodically protected steel without coating. BGE no longer has either of these types of material in its distribution main and service lines, according to PHMSA data.
In 2016, BGE invested almost $115 million in STRIDE projects, according to Mulcahy.
At Memphis Light Gas and Water Division, which had the third-highest ratio of leaks per mile on gas mains and service lines, the most common leak cause was equipment related. These issues related to pipe fittings and valves, but not the pipe itself, the utility noted in a recent email. The utility said it spent almost $9.5 million on planned and emergency maintenance — which includes leak repairs — over 2016.
The Memphis Gas Light Co., the city's first utility company and a predecessor to today's Memphis Light Gas and Water, was formed in 1852.
Memphis Light Gas and Water's gas division is working through a 30-year cast-iron pipe retrofit program, which is on track for completion in 2022. The utility in 2016 spent $4.7 million on retrofitting cast iron and steel taps and devoted a total of $1.8 million to pipeline integrity work, according to its 2016 annual report. In 2015, Memphis Light Gas spent $2.4 million on retrofitting aging taps and $2.3 million on pipeline integrity.
The utilities with the lowest ratios of distribution main and service line leaks repaired in 2016 continued to be those that have few, if any, miles of leak-prone materials. Out of the 10 utilities with at least 5,000 miles of distribution main and service lines that had the lowest leak repair ratios, only two had any iron in the main and service lines. New York State Electric & Gas Corp. reported less than 0.2% of its system was iron, while Rochester Gas and Electric Corp. reported a similar number.
Bare steel without cathodic protection, bare steel with cathodic protection and coated steel without cathodic protection also showed up sparsely among the companies with low leak ratios. West Texas Gas Inc. had the highest percentage of both protected and unprotected bare steel on its system, with 2.2% of each. New York State Electric & Gas had the highest percentage of unprotected coated steel, with 2.8%.