Md. water utility puts technology to work on aging pipes
Wednesday, December 16, 2009
Nearly a year after a broken pipe flooded River Road in Bethesda and stranded motorists, officials from suburban Maryland's water and sewer authority on Tuesday showcased technology designed to detect problems in the largest water mains.
The Washington Suburban Sanitary Commission will be relying on a black foam sphere slightly larger than a softball to find the hissing of leaking pipes and a four-wheel cart with electromagnetic equipment to detect which reinforcing steel wires have snapped.
"If we'd had this in place several years ago, I'd like to think we could have seen this coming and we wouldn't have let this happen," Gary J. Gumm, WSSC's chief engineer, said at a media event at River Road and Clewerwall Drive, the site of last year's break.
The WSSC began using the "Smart Ball" and electromagnetic technology in 2007, but officials highlighted their efforts Tuesday as part of a public relations campaign launched in the fall. The utility is struggling to maintain a network of aging underground pipes. The WSSC, which delivers water and sewer services to 1.8 million people in Montgomery and Prince George's counties, drew national scrutiny after the Dec. 23 River Road break, when firefighters and police using helicopters and boats rescued nine motorists from a torrent of frigid water.
The WSSC spends most of the winter repairing hundreds of smaller iron pipes that burst when temperatures fluctuate, causing pipes to expand and contract. The larger concrete pipes, such as the 66-inch main that burst along River Road, break far less frequently but cause the most concern because the highly pressurized feeder lines carry so much water.
The River Road break took part of the major commuter route between Potomac and Bethesda and the District out of service for eight days and led to 35 million gallons of drinking water being lost. Montgomery officials, noting that there were no serious injuries or drownings, have credited the quick efforts of rescue workers.
In addition to the River Road pipe problems, WSSC officials have said they probably averted a potentially disastrous break by finding a leak in a major pipe near the Capital Beltway in College Park in October 2008. Other breaks of massive pipes in Derwood and Temple Hills in the past two years led to widespread boil-water advisories for residents and businesses.
Jerry N. Johnson, the WSSC's new general manager, said the Smart Ball and electromagnetic technology are part of the utility's stepped-up efforts to inspect and repair 10.2 miles of the largest concrete mains last fiscal year and another 12.9 miles this fiscal year. Earlier this decade, inspections of such mains dried up for six years when the WSSC had no customer rate increases and lost half of its maintenance staff to buyouts and attrition.
The WSSC plans to have all 77 miles of the largest concrete mains, four feet in diameter and larger, inspected by fiscal year 2013, Johnson said. After fixing the pipes, the utility leaves behind fiber-optic wires that detect the sounds of the reinforcing steel wires as they break, signaling where a pipe is deteriorating.
Asked how concerned he is about the possibility of another massive water-main break, Johnson said, "We're confident we've taken the steps necessary to offer as much confidence as we can offer by inspecting, repairing and replacing sections of pipe that we can."
The WSSC is now using the Smart Ball and electromagnetic technology to inspect parts of the 7.3-mile River Road pipe. The foam ball, which has what looks like an aluminum tennis ball tucked inside, sinks to the bottom of a pipe and rolls along in the current, said Mark Holley, president of Pure Technologies, the Columbia firm that provides it. Equipment inside the aluminum ball picks up the hissing sounds of any leaks, and the data are then downloaded to a computer, Holley said.
After the pipe is drained, Holley said, workers push the cart, which resembles a steel bike, through the pipe. Electromagnetic coils attached to a computer on the cart detect which of the hundreds of steel wires that reinforce the concrete have snapped, giving the utility a general idea of the pipe's condition.