Called PipeDiver, the tool is dropped into one end of a water main where it scans the interior with an electromagnetic field. It stores the data and is carried downstream and then is extracted at the other end of the line. Analysts upload the data and create a virtual map of pipe sections, looking for structural disturbances that could indicate damage.
The technology allows water to flow uninterrupted to homes and businesses, instead of shutting down service to do a manual, visual inspection of the pipe’s stability.
Baltimore used PipeDiver earlier this month to evaluate a 6.5-mile stretch of concrete cylinder pipe that services part of the city, along with areas of Baltimore, Howard and Anne Arundel counties in Maryland. Structural analysis of the water main is expected back in a few weeks.
Kurt Kocher, a spokesman for the Baltimore Department of Public Works, said not shutting down water service to do the work was a critical factor in using the technology, as the pipeline delivers water to major facilities in the area.
Pure Technologies is conducting the work and has had PipeDiver in its arsenal for a couple of years. The company specializes in inspecting, monitoring and the management of physical infrastructure such as water and hydrocarbon pipelines, buildings and bridges.
Travis Wagner, an engineering manager with the company, called the technology “a rather in-depth process” and said it’s engineered by the company to use electromagnetic fields to scan “pre-stressed” pipe.
After data from the PipeDiver is recovered, specially trained analysts create a table of each 16- to 20-foot section of a pipe and examine the electromagnetic signal for both the location and magnitude of the stress on the pipe. The information is rechecked and then compared to any previously available data on the specific pipe section.
Wagner added that electromagnetic inspection devices similar to PipeDiver have been used in the gas industry for years, but the technology is just now being adapted for use in water pipes.
“PipeDiver’s theory of deployment came from that idea, but it’s not as cumbersome,” Wagner said. “It doesn’t take specialized insertion and extraction equipment.”
Bursting at the Seams
The Baltimore project comes with a hefty price tag — $1.5 million. That number includes the inspection and also some potential repairs, once the analysis uncovers what sections of the water main may need some work done.
The area has a history of water main problems.
Maryland has experienced a variety of ruptures over the years, including one in Howard County in June 1990. County officials traced the cause to construction defects. According to The Baltimore Sun, that burst was the sixth in the pipeline since 1979. The pipes were supposed to last for more than a century.
Another incident occurred in Towson in 2002 and most recently, in Dundalk in 2009, which flooded roads, cars and homes.
Kocher said Baltimore started investigating the stability of its pre-stressed concrete pipes after the Towson rupture and has made it a priority to stay abreast of the latest technology to help spot potential problems with the water mains before they happen.
The current Baltimore water main under evaluation is one of the primary transmission pipes in the northwest service area of the city. The cost of the job has the price of some preliminary repair estimates built in, but Wagner pointed out that usually 1 percent or less actually need any sort of major overhaul.
Wagner said that just because PipeDiver may uncover a small amount of distress on a pipe doesn’t necessarily mean it has to be replaced. By being proactive now in identifying those trouble areas with the probe, Baltimore could potentially save millions of dollars — and ensure the health of the Charm City’s underground infrastructure — in the future.
“Oftentimes we’re talking about one or two leaks or failures on a pipe. … We can manage these for a very small percentage of the cost a replacement,” Wagner said.
