To Line or Not to Line

Newark, Del., Uses Acoustic Condition Assessment to Determine How to Proceed with Pipe Rehabilitation

Acoustic Condition Assessment

Municipalities are constantly faced with the need to do more with less. Public works departments must routinely make the most out of limited budgets, so projects must be completed both quickly and cost-effectively. Many utilities will consider lining existing water mains rather than replacing it, as the cost savings can be significant and the work can be completed with minimal disruption to neighborhoods and traffic.

However, lining is not always the best solution for certain pipeline problems, so it is crucial for municipalities to learn as much as they can about the condition of their pipes before embarking on a rehabilitation program. Echologics’ ePulse acoustic condition assessment technology is one tool that can be used to determine the proper course of action, as officials in Newark, Del., can attest.

Trouble Beneath the Surface

Located in Northern Delaware, Newark had an estimated population of nearly 34,000 as of 2015, according to the U.S. Census Bureau. Known primarily for being the home of the University of Delaware – the largest university in the state with a total enrollment of 23,009 – the city is located on 8.9 sq-miles of land and has approximately 140 miles of water mains. In recent years, the condition of the pipes has become a growing concern.

“We’ve had an increasing number of main breaks per year since we started keeping records in the 1970s,” says Tom Coleman, P.E., director of public works and water resources for the City of Newark. “The number of breaks that we have per year has approximately doubled.”

Coleman’s department has developed a plan for addressing its pipe problems, but its progress is impaired by the cost of implementation.

“Starting in 2014, we began a more aggressive water main replacement program,” he says. “Our goal, if we were to replace on service life, would be a mile and a half a year – approximately 1 percent of the pipe in the ground. Replacement costs have been rising faster than inflation and it’s going to become more difficult to get the money together to hit our target. We wanted to investigate whether relining with cement mortar could be a possible tool in the toolbox to extend the life of our buried pipe assets.”

If pipe is found to be suitable for lining rather than replacement, the cost and hassle of addressing the problem can be significantly reduced.

“Replacement is very disruptive,” says John Marciszewski, director of business development for Echologics. “You have to dig up a whole street. Cleaning and lining is pretty much trenchless. You can go in and have somebody’s water turned back on in a day or two. It’s very different than when you’re dealing with a replacement project. It takes less planning [and] it’s more environmentally green.”

Echologics team assesses pipe

After the Echologics team performed an assessment of the pipe, the amount of structural wall thickness left was determined.

Sounding Off

But deciding whether or not a pipe can be lined is far easier said than done. A pipe’s condition needs to be thoroughly assessed in order to determine if the pipe has the requisite structural stability to qualify for lining rather than replacement. Liners can also be either non-structural (such as cement mortar, which are lower cost) or structural (fully or semi), which come at a higher cost but extend pipe life by several more years. This is why Coleman and his team decided to deploy ePulse acoustic condition assessment technology to help find out exactly what is going on with the city’s aging water mains.

“[Coleman] is an innovative thinker, and that’s what it always takes,” Marciszewski says. “He wanted to take a look and make sure they were making the most effective use of utility funds, yet doing the right thing for the long term.”

The ePulse technology is a non-invasive acoustic technology that assesses a pipe’s condition, detects leaks and determines the pipeline’s remaining service life. After the Echologics team performs an assessment of the pipe, the amount of structural wall thickness left is determined.

“We do some estimates based on the amount of structural material left [to find out] how long that pipe has to live,” Marciszewski says. “Based on that, these utilities will determine the most appropriate cleaning and lining technology that’s required. This could range from a non-structural liner like cement mortar, to a fully structural liner like 3M Scotchkote.”

Coleman and his team chose to examine pipes in a number of different city locations using ePulse technology. “We worked with John from Echologics and put together a project where we looked at our most critical pipes, which were pipes under major roads, railroad tracks and rivers,” Coleman said. “We also went out and did a few lines that we thought would be representative of the neighborhoods that they’re in.”

All told, the Echologics team assessed the condition of 12,403 ft of 6- to 12-in. pipe, most of which was pit-cast or spin-cast iron, as well as one segment of steel pipe.

They were very accommodating,” Coleman says. “The work in the field went smoothly, and they were able to work around our traffic and train constraints. The railroad and highways were all active during the project.”

ePulse is used to assess pipes under major roads

The City of Newark and Echologics put together a project to assess the city’s most critical pipes using ePulse, including pipes located under major roads, railroad tracks and rivers.

Out of the Dark

The Echologics report revealed that much of the pipe tested in Newark was found to have too much structural degradation to be suitable for non-structural lining. This was not what Coleman hoped would be found, but said he was glad to know for certain what was going on in the city’s pipes rather than relying on guesswork.

“It gave us some really good data. Unfortunately, we didn’t get any that said, ‘Let’s do some lining,’” says Coleman of the assessment’s results. “Our pipe looks to be in worse condition than we had hoped. Two-thirds of the wall thickness has corroded away on some of our residential streets.”

Coleman says these were the areas where they had severe and frequent discoloration of water and very low fire flows, so there was anticipated tuberculation in the pipe. “We were hoping enough would be left that we could line it with cement mortar, but the results pretty much confirmed what we had anticipated,” he says.

In fact, the Echologics analysis revealed some information about some of Newark’s pipes that surprised even Coleman.

“In one neighborhood, we inspected two streets that we thought were built in one direction, but it appears that they were built in the other direction, with two different batches of pipe,” he says. “On Wilson Road, over 60 percent of the wall thickness had been lost; the first pipe segment on Sypherd Drive was also about 60 percent. But then the next two pipe segments in Sypherd had no measurable loss, so they must have changed from an unlined pipe to a lined pipe mid-block, and we were able to capture that with the Echologics report.”

Coleman and his team were able to determine approximately when the switch to the lined pipe was made, and that information will help them decide which pipes to test next. He cites the data made possible by Echologics’ technology as key to helping the City of Newark make more informed decisions on its rehabilitation methodology.

This story was contributed to Water Finance & Management by Echologics.

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