Correction: Due to an error in a report by the Washington Suburban Sanitary Commission, an earlier version of this article incorrectly stated that such pipes can explode with the force of up to 200 tons of dynamite. The correct measure is up to 200 pounds of dynamite, according to the WSSC.
The water utility for Montgomery and Prince George’s counties says its largest concrete pipes are potentially so dangerous if they burst that all new buildings within 80 feet of the underground mains should be required to be fortified to withstand explosive forces.
Officials at the Washington Suburban Sanitary Commission say they need to protect people in future homes, schools, offices and other new buildings from the largest of their aging pipes — five of which have succumbed to “catastrophic failure” since 1996. The highly pressurized water mains, some of which are so big they could accommodate a minivan, explode with the force of 20 to 200 pounds of dynamite and spew water at up to 90 mph, according to a WSSC analysis.
No one has been seriously injured in a break, but WSSC officials say they’re concerned about recent close calls. Firefighters and police had to rescue stranded motorists from a torrent of frigid water when a 66-inch main burst along River Road in Bethesda in December 2008. When a 54-inch pipe burst in a parking lot of a Capitol Heights office park in January 2011, the blast of water blew off doors and ripped out walls. Nearby workers said they thought a bomb had gone off.
“If you’re going to build in an earthquake zone, you have to take into account an earthquake and how buildings would survive it,” said Gary J. Gumm, WSSC’s chief engineer. “This is similar to that.”
But developers are pushing back, saying an 80-foot setback would severely restrict use of their land and probably would require more expensive construction. If WSSC is concerned that its pipes pose a danger, they say, the utility should pay property owners for land needed to provide a safer buffer.
WSSC’s six commissioners, who are appointed by the two county executives, are scheduled to vote on the issue as early as June 20. A public hearing on the setback proposal is scheduled for June 6 at 7 p.m. at WSSC’s headquarters, 14501 Sweitzer Lane in Laurel.
Two of the large mains, including one that is almost 70 years old, run through the 488-acre site planned for apartments, condominiums and townhouses in the new Konterra Town Center East near Interstate 95 in Prince George’s.
“They have right of way for their pipes, and we can use our land up to their right of way as we see fit and the county allows,” said Caleb Gould, the project’s developer. “If they want us to fortify buildings because they have a dangerous pipe in their right of way, we’d need to be compensated for that.”
Asked whether he would be nervous about building homes near a potentially dangerous pipe, Gould said, “I’m not nervous because WSSC is liable for [its pipes]. They’re the guys who are supposed to keep their pipes safe.”
WSSC officials say the agency and water utilities nationwide began seeing breaks in the larger concrete mains in the 1970s because water seeped through pipes’ cracked concrete walls and corroded reinforcing steel wires. WSSC has 145 miles of such pipes throughout both counties.
The setback requirement also would cover 18 miles of large cast-iron pipes, which haven’t posed a problem but can be brittle, Gumm said.
WSSC signs off on development plans as part of the approval process. The utility says it would not prohibit new building within the 80-foot setback. However, it would require that the developer’s engineer certify that any buildings within the zone could withstand the force of a large break. Developers could either leave open space in areas near pipes or fortify buildings with extra-strong windows and thicker walls, Gumm said.
WSSC officials concede that many people, probably unknowingly, live or work within 80 feet of such pipes. Some homes were even mistakenly built within WSSC’s pipe right of way, Gumm said. He said WSSC has not tallied how many buildings are within the 80-foot zone.
The utility, citing security concerns, declined to specify where the largest mains are.
While the largest pipes were installed decades ago along major roads and through open fields, development has encroached, Gumm said. For many years, WSSC had a pipe setback policy of 25 feet. In 2008, it modified the requirement, putting in place the current, ambiguous provision that states only that new development proposed within 200 feet of large pipes might have “special considerations and modifications” imposed. That, Gumm said, was too vague and didn’t reflect more recent analysis showing the danger zone at 80 feet.
Jude Burke, who manages Montgomery and Prince George’s projects for McLean-based Elm Street Development, asked how WSSC came up with the 80-foot zone.
“If you have to build a concrete fortress” within 80 feet of a large pipe, Burke said, “it’s still going to impact the property.”
Gould said WSSC should replace its larger mains during the early construction phases of new developments, when roads and other infrastructure are being built.
Gumm said it would be cost-prohibitive to replace all 145 miles of the largest concrete pipe and unfeasible to take the major lines out of service long enough to do so.
The setback is intended to provide “a little extra safety margin,” he said. WSSC also is stepping up pipe inspections and replacements, Gumm said. During inspections, WSSC leaves behind new fiber-optic equipment that monitors a pipe constantly. In 2010, such equipment signaled that steel wires in a 96-inch pipe in Potomac were beginning to snap quickly, allowing the utility to replace the weakening pipe before it broke.
WSSC officials said that to address some county officials’ concerns that a stricter setback requirement would inhibit economic development, WSSC would exempt projects where a site was being redeveloped or expanded. It would be impractical, WSSC officials said, to require that new buildings be stronger or set back farther if they were built alongside older buildings that weren’t.