Repair, Then Replace

May 23, 2013

“The nation’s drinking water infrastructure, especially the underground pipes that deliver safe water to America’s homes and businesses, is aging and in need of significant reinvestment,” according to “Buried No Longer”, a 2012 American Water Works Association (AWWA) report.

“Buried No Longer” reveals that the costs to replace our aging water infrastructure tops out at $1 trillion over the next 25 years if we are to maintain current levels of water service.

The report broadens a smaller study AWWA completed over a decade ago–“Dawn of the Replacement Era”–beyond the 20 original cities examined then to encompass the entire United States. “[Buried No Longer] confirms what every water utility professional knows: we face the need for massive reinvestment in our water infrastructure over the coming decades. The pipe networks that were largely built and paid for by earlier generations–and passed down to us as an inheritance–last a long time, but they are not immortal,” the report concludes.

The report can be found on AWWA’s website .

The Plastics Pipe Institute (PPI) is the leading trade association representing all segments of the plastics piping industry. It also promotes HDPE on its website. Commenting on the need for substantial investments in water infrastructure, Executive Director Tony Radoszewski says the US Conference of Mayors created a water council to study the situation. “This is the most challenging issue facing mayors,” he says.

“As long as constituents can get water, they are happy,” adds Radoszewski.

As a result, mayors are in a sticky situation. For example, 25% of Atlanta’s population lives below the poverty line, he says. Where will that city come up with the money to pay for major water main replacement?

Cliff Wilson, president of Wachs Water Services, agrees with the need for new funding. “The liability we have as a country has increased,” he says. “From my perspective, the $1 trillion [that AWWA says is needed] is an investment in new pipe.”

Pipe manufacturers make good pipe, and while some 150-year-old pipes are in remarkably good shape, some 12-year-old pipes are in terrible condition due to soil corrosion, Wilson says.

Wilson also says the first and fastest investment is in controls, creating an opportunity to trim that $1 trillion back. “We, as an industry, have been focused on pipes. If the control valves on each main all work, knowing where they are, the whole system can be fine-tuned. We can narrow a problem down to a very narrow piece of the main and reduce the risk. The same applies to the aging transmission lines where a utility may be able to replace miles at a time, or one mile,” he says.

Wachs Water Services helps utilities increase controls on their distribution pipelines. A number of utilities have ongoing programs–what Wilson calls systemic asset management. Wilson first recommends inventorying the “as-is” versus “as-built” status of control valves, then assessing conditions, and determining the level of service required. There are enormous savings if you can reduce the footprint and time of any problem, he says, because a pipe renewal program takes a long time and lots of money.

“The capital investment may not be as large as you first estimated,” he says.

Wilson says when a water main system is surveyed, 60% of the valves can be found to be operating. The other 40% cannot be located, he says. The reasons? Maps have changed, or the valves may have been removed. Or, they cannot be accessed because they’ve been covered up by asphalt or concrete. Finally, once the valves are located and/or asphalt or concrete is removed, it must be determined if they actually work.

If a valve doesn’t work, it must be determined if it is open or shut. If there are other valves in the area, it may not be needed, but that involves knowledge of the rest of the system. If the valve is broken shut, residents or businesses may not be getting enough water, and they are experiencing low water pressure, or it may have created a dead end with stagnant water sitting in the pipe creating a water quality concern. If water is pumped through the back way, water flow through hydrants may be affected.

Most utilities have some kind of replacement plan, but they may have trouble funding it. One of the real challenges those plans have is they are “desktop”, in Wilson’s words, and not based on what truly is.

“A progressive utility will fine-tune its desktop plan by updating records and actually rehabilitating assets,” he says.

Wilson says the City of Atlanta went through every valve and fire hydrant by identifying and repairing each one. They then could focus on their capital project, “which is truly the smallest piece of work for the biggest payoff.”

Selective Rehab Preferred
Utilities started laying cast iron water mains in the late 1800s, and by the end of World War II, precast concrete pipes were being laid since iron was in short supply. Between now and 2030, “we will start to see lines failing,” says Norvin Eitzen, marketing coordinator at Pure Technologies. “We are working with utilities to find where the failures will occur,” he says, essentially diagnosing the health of utilities’ pipeline systems.

Pure Technologies, headquartered in Calgary, Canada, assesses a utility’s water mains and makes recommendations on rehabilitation versus capital replacement. “When we inspect a pipeline, 1 to 4% is in a state of distress, says Eitzen. “Roughly a half percent is critical enough that water line replacement is necessary.” Anything less critical can be rehabilitated.

Selective rehabilitation is preferred, since replacing a 5-mile section of pipe demands capital funding. Replacing one section of pipe will avoid that capital expense and is the best argument for proactive leak detection.

Utilities are responding extremely positively, Eitzen says. Some will dig up a pipeline to verify a recommendation, perhaps because they are suspicious of the technology. Once trust builds up, the utility management will sign up for a pipeline management program, he says.

In the late 1990s, Pure Technologies took a technology that originated at Queens University in Ontario and created the electromagnetic detection system for precast concrete pressure pipes. The concrete pipe is wrapped in mesh wire and layered with more concrete. This gives the pipe the strength needed to handle the internal pressure of water rushing through transmission lines.

One of Pure Technology’s several inspection robots–Pipe Diver, Pipe Crawler, Pipe Walker–is inserted in a water main, and it creates an electromagnetic field that detects where wires are broken. This is where the pipeline will eventually fail, Eitzen says.

Different detection technologies are used to detect leaks in cast iron pipes. Smart balls called “Sahara” are acoustic sensors that identify leaks while the system is in operation. Eitzen explains it is too costly for a utility to shut down a line and dewater it before inspection.

Pure Technologies’ pipeline management program consists of inspections, monitoring and recommendations. Inspections are usually carried out every three to five years–sooner if the pipes are in an urban setting. A rural utility’s water mains may be on a 10-year inspection cycle because they are not subject to the same wear and tear.

Once a water line is inspected, “you know where the stress is, and it can be monitored going forward,” explains Eitzen. The company recommends repairs or replacement either after inspections or following monitoring. When monitoring is done on a permanent basis, fiber optic cables are used. The utility is immediately notified when a break or leak is detected.

Allocate Funding Yearly
Louisville Water began supplying water in 1860 with 26 miles of pipe, primarily cast iron and wooden water mains. Today, it maintains over 4,100 miles of pipe, including a small section of the original cast iron main. The current infrastructure includes cast iron, ductile iron, prestressed concrete, PVC, and copper lines.

Louisville Water began a transmission main improvement program in 2009. Since the 1980s, it has had what it calls an aggressive program to assess, repair, or replace distribution mains. It began its transmission main program much later because the technologies for assessments of these larger lines (over 20 inches in diameter) were developed in the last 10 years.

The utility holds a five-year master contract with Pure Technologies to regularly inspect prestressed concrete mains for leaks and a five-year contract with CP Systems for a cathodic protection system for its cast iron and ductile iron water mains.

Pat Howard, a project engineer with Louisville Water, says the department allocates $5 million every year for transmission main replacement or repairs and has invested over $165 million to date–the cathodic protection program, in place since 2004, is funded this way. “Our transmission system is our life line,” he says. “So we’re taking a more aggressive approach.”

Louisville Water’s ability to invest its own money in infrastructure replacement, even though its water rates are some of the lowest in the region, may be because it has an abundant source of water–the city sits beside the Ohio River with 75 million gallons of water flowing by every day.

“We chart all main breaks, including their frequency,” says Howard. The department averages between 600 and 700 water main breaks each year and its goal is to control its maintenance activities to 600 breaks a year. Transmission line breaks are infrequent, but can be costly and will have a far larger impact when they occur than a break in a distribution line. In 2011, there were two transmission line breaks, and Howard worked on one, he says.

In that second break, the 24-inch prestressed concrete pipe was installed 30 years ago on top of a rock. Earth movement allowed the rock to wear down the prestressed concrete to the reinforcing wire wrapped around the inner layer of concrete, leading to corrosion.

The department has seen a significant impact with the cathodic protection program. The frequency of breaks has flatlined, he says.

“I think we are a model for other utilities,” says Howard. “We feel like we have an aggressive approach toward improving our infrastructure.”

Andy Williams, also with Louisville Water, said the utility signed its five-year master contract with Pure Technologies recently after the company had worked on several projects for the utility beginning in 2010. Their work is part of the Prestressed Concrete Main Condition Assessment Program.

Williams says Pure Technologies’ inspection robots contain computers with a receiver on the tip of the fin. After being inserted into the pipe, the Pipe Driver, for example, moves through the main propelled by the flow of water while producing the electromagnetic field needed to detect the broken wire. The Pipe Driver is then removed from the line once its detective work has identified all broken wires and the contents of its computer are downloaded for review.

“The results are sent to a structural engineer who provides a structural risk assessment. It tells us if it needs to be fixed or monitored,” says Williams. The department has dug up pipes where a distorted signal was detected and verified 90% of the breaks, he says.

Williams is convinced Pure Technologies’ technology and work saves money. A single break in a 60-inch main in May 2009 cost up to $1 million to repair, he says, not counting the lost water and loss of service to businesses in the area. In contrast, a recent project cost $3.5 million in which six to nine potential breaks in a main identified by Pure Technologies’ Pipe Driver and Pipe Crawler were repaired and valves and drains were rehabilitated.

Get Best Value for Dollar
Municipalities don’t replace whole main systems at one fell swoop. Instead, they have programs in which they spend a portion of their budget on extending the lifetime of the water mains and another portion on replacing sections, says Ken Ripley, project manager at CP Systems, headquartered in Whitby, Ontario, Canada. The company installs cathodic protection systems on cast iron and ductile iron water mains.

Cathodic protection systems extend the life of the ductile or cast iron water mains by 20 to 25 years, providing municipalities with cost savings, says Ripley. A cathodic protection system consists of installing sacrificial anodes at predetermined distances over the length of cast-iron and ductile-iron water mains. The anode corrodes instead of the main, thereby extending the life of the main and assisting in the prevention of water main breaks and leaks, sometimes for decades.

Ripley says the key is getting the best value for the dollar. He gave a hypothetical example: Given 100 miles of pipe, this year five miles can be replaced, and 5 miles can be cathodically protected. Over 10 years, the whole system will be replaced or cathodically protected.

The cost of installing one cathodic anode is approximately $300 and will protect 45 feet of pipe for the next 20 years, Ripley says. On the other hand, the average cost of replacing a water main where a break has occurred can range from $4,000 to $5,000. A utility must decide which option fits its budget since residents ultimately pay for the repairs in their utility tax, and businesses suffer from lost revenue due to street closures.

“Our goal for each municipal utility is to implement a protection plan. If they do a little bit each year to reduce the main breaks,” they will enjoy cost savings every year, says Ripley, and they will extend the infrastructure.

CP Systems technicians complete a survey along the water main prior to installing the cathodic protection anodes, to measure the amount of current running through the main. This indicates how susceptible to corrosion the main is, and pinpoints to a certain degree the areas that are most in need of cathodic protection.

Sacrificial anodes are installed with either a vacuum excavation truck or an auger truck drilling down to the main through a 10-inch diameter hole. The sacrificial anode is then welded into place, and the hole is backfilled and resodded. Another survey of the water main is carried out sometime after the installation. The two surveys are then compared side-by-side, and the difference in potential between the pre-survey and the post-survey shows the increase in protection of the water main.

Plan for the Long Term
The City of Palo Alto, CA, launched a long-term plan in 1991 to replace its aging cast iron distribution mains, first laid when the water utility was founded in 1896, over a 20-year period.

PVC and ductile iron pipes were the primary materials of choice and were used between 1987 and 2008. Polyethylene was first installed on the City’s system in 1994 as a pilot study, and then another small quantity was installed 10 years later. Once proven and tested on the City’s water system full-scale polyethylene water main installations began in 2009 and are now a city standard replacement material.

Greg Scoby, a retired engineering manager for Palo Alto’s water, gas, and sewer utilities, says Palo Alto is progressive in replacing its mains. The water utility experienced recurring breaks in the late 1980s, and recognized it needed to update its maps and get infrastructure replacement up to date. Furthermore, the water main infrastructure replacement cycle was due to begin in 1986.

Therefore, when the utility engineering section told the city council in 1991, they had to accelerate their infrastructure replacement program, the city council agreed. It currently is replacing 200 miles of distribution water mains at a rate of three miles a year, up from 1 mile a year before 1991.

Palo Alto, which is home to Stanford University, has an educated, primarily residential population. As Romel Antonio, a senior project engineer, explains, a pay-as-you-go policy has been maintained, and water rates have been increased several times to fund its proactive replacement program for both its gas and water lines, and most recently for increased commodity costs and a suite of emergency projects.

Antonio says when the city began expanding starting in the late “˜40s, steel/concrete cylinder transmission mains were laid to transport water to the distribution lines. There are no service line connections on these transmission mains; there have been no breaks, and they are not being targeted for replacement, Antonio says.

Scoby explains that polyethylene pipe was chosen over PVC pipe to replace the aging cast iron pipes for several reasons. There is no need for mechanical joints, explained Scoby. Most leaks are associated with joints. Using materials that don’t corrode, have no mechanical joints and are flexible can extend the life of the mains, he says.

The Plastics Pipe Institute’s Radoszewski explains, “We believe that using polyethylene as material for water mains has a unique feature.”

It does not need to use the bell and spigot to join two ductile iron or PVC pipes. With polyethylene, the two ends can be melted and pushed together to seamlessly meld, creating a monolithic pipe stream.

Scoby says, “We tested the materials based on ground temperatures, water PH levels, and types of disinfectant used. Testing showed polyethylene extended the lifetime of pipes over materials previously used.”

Scoby also says the department started using full-scale trenchless installation in 2009 for its water infrastructure replacement program. “We were able to reduce the installed costs with trenchless techniques and no longer have to dig trenches.” Minimizing the amount of pavement that has to be disturbed reduces the costs significantly.

ISCO Industries fabricates and supplies most types of pipe, but HDPE, or polyethylene is its core product making up almost half of its sales, according to Steve Bredemeier, regional sales manager. Jeff Henderson, the company’s director of waterworks said trenchless or directional drilling to install polyethylene pipes is tremendously popular since they can be pushed through existing cast iron lines. For example, an 8- or 10-inch polyethylene can be pushed in to enclose an 8-inch existing line, thereby avoiding having to dig up the old line.

Bredemeier says municipal water agencies struggling for funds repair lines rather than replacing them. But many times trenchless installation can cut replacement costs. For example, a utility may replace a water main the traditional way with open cuts for $200,000. However, a trenchless installation can reduce the cost by $50,000.

Back in Palo Alto, Scoby says while street cut fees can increase revenues for the city, they can increase the cost of a project for the water department. These are fees paid by utilities, cable companies, and telephone companies to lay or repair lines under streets. And trenchless technology can cut down on those fees.

Scoby says the decision to replace a line is based on performance, not age. If a water main is requiring a lot of maintenance, it should be replaced, he says.

“We were doing replacement for the most part by running a new line parallel to the old line that is being replaced. Once customers have all been moved to the new line, the old one is abandoned.”

There are times when trenchless installation may not be the best choice. When there is a high-density of utilities under the street, it is preferable to do an open cut, Scoby says. In this circumstance, a lot of potholes would be required to install pipe using trenchless technology, and that might drive up the project cost.

Starting in August 2012, the city replaced 19,500 lineal feet of customer service lines with high-density polyethylene pipe in diameters ranging from eight inches to 16 inches, and it installed 33 new fire hydrants at a cost of $4.2 million. The job was expected to be completed in late May.

Scoby says it is disappointing to see the lack of passion at some utilities to not accept new technologies such as GIS. “As long as you’ve got innovative people around who accept new technology, you can get a lot done.”

For example, Scoby points out that there is “a crazy amount of data on pipes.” The attributes of each installed segment of pipe can be loaded into a giant excel sheet associated with GIS systems. By collecting data during construction, future generations will be able to conduct meaningful trend analyses when determining portions of the system that require maintenance or replacement, he says.

For more information on the City of Palo Alto’s water system and infrastructure program, visit www.cityofpaloalto.org.

About the Author

Lyn Corum

Lyn Corum is a technical writer specializing in water and energy topics.

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