Aging pipes threaten buildings, homes

Water main blast could have power of 200 tons of dynamite, engineers say

The water distribution system includes 143 miles of these large, high-pressure mains, and much of it is made of materials that are at or near the end of their lifespan. They are at risk of ‘‘catastrophic failure,” according to the utility’s studies.

Rising water main failure risks are not limited to the Washington region, experts say.

‘‘It’s not a crisis yet, but if we don’t start reinvesting ... it very well could be,” said Kylah Hedding, spokeswoman for the Denver-based American Waterworks Association, which represents 4,700 utilities as well as manufacturers and consultants involved in the water industry.

‘‘It’s a bigger issue where the older water systems are,” Hedding said, adding that the WSSC is an older system.

At a Montgomery County Planning Board forum last fall, then-WSSC General Manager Andrew Brunhart warned the resulting explosion would be like ‘‘a missile.” Such an explosion could have the force of 20 to 200 tons of dynamite, WSSC engineers say.

If mains blow near development, ‘‘they are likely to take some houses with them,” Brunhart said at the forum.

Current standards allow buildings to be constructed as close as 23.5 feet to 33.5 feet from the large mains. But WSSC engineers and analysts are recommending that the setback be increased to 80 feet from the center of the mains, which range from 3 feet to 8 feet in diameter.

A recent analysis by the utility made available earlier this year indicates that 200 buildings in the two counties are at heightened risk because they are in or next to WSSC’s rights of way for large water mains.

At least 690 buildings are closer than the recommended 80-foot setback, the utility’s officials said Tuesday.

As undeveloped land becomes scarcer in the two counties, pressure is building to place homes and businesses closer to water mains, they said.

‘‘The new thing we are concerned about is ... the desire to start to encroach on some of these pipes,” said Gary J. Gumm, WSSC’s chief engineer — particularly in the case of proposed high-density development.

Even the recommended standard would not put people and property out of harm’s way if a large pipe burst.

‘‘We’re trying to balance risk associated with these pipes and the desire of development to use the property that they own,” Gumm said.

‘‘It’s not practical to require that much land not be developed,” said Ross A. Beschner, manager of the WSSC’s water main risk assessment.

But putting more people and property in range of a potential high-pressure pipe break increases risk, as well as the need for monitoring, repairs and money to pay for both, according to the WSSC’s studies.

The WSSC’s assessment program was trimmed in the past decade under pressure not to increase rates and the threat of turning the public utility over to a private operator.

The WSSC’s current budget allocated $1 million for water main assessment, but the agency’s proposed budget for the fiscal year that begins July 1 tied money for the program to an ‘‘infrastructure renewal fee.” But the utility’s governing board has rejected that fee.

WSSC engineers are looking at whether money allocated for assessments, repair and replacements will be enough.

Last year, the utility’s workers laid 12 miles of fiber-optic cable along large mains in Potomac and Adelphi to give them round-the-clock notice of an impending break. They plan to install five more miles of such cable next month and had hoped to add more during the budget year that begins July 1.

In June, an in-person inspection detected a leak in an 8-foot main on Duryea Drive in Potomac.

The utility’s photos of that repair show the water main, which is the largest size in the WSSC distribution system, running by or through at least one house’s back yard.

‘‘That was within a stone’s throw,” Gumm said.