Making Waves with Trenchless
Most people are aware that around 80 percent of the world is covered by water— and possibly it’s that knowledge that allows us to take it for granted.Because if you think about it, what is the only beverage you can get for free ata restaurant? What’s the only liquid in the house you don’t seem to mind pouringgallons of down the drain? Ironically, water also happens to be vital to oursurvival and only about 1 percent of the world’s entire supply is actuallydrinkable and accessible.
Recently, the value of drinking water hasbecome a little clearer. In 2002, the U.S. Environmental Protection Agency (EPA)released its Clean Water and Drinking Water Infrastructure GapAnalysis, estimating the spending required to avoid falling behind ininfrastructure replacement over the next 20 years. The realizations thatfollowed gave the quality of the water infrastructure some long-overdueattention — spurring important discussion throughout the industry.
“Fiveyears ago no one was really talking about the water industry, because watercompanies didn’t believe there was any significant need to rehabilitate theirdistribution lines,” recalls Mark Smith, president of Underground SolutionsInc., manufacturer of the Duraliner system, a fully structural PVC system andFusible PVC. “But when the EPA Gap Analysis came out, those companieswere able to add definition to how big their problem really was. That openedeveryone’s eyes and ever since, everyone has been scrambling to try to find outhow we’re going to get all this work done.”
Water Quality
Findings in a 2004American Water Works Association (AWWA) report revealed how much people reallydo value drinking water. According to AWWA executive director Jack Hoffbuhr, akey finding of the study was that most people do in fact undervalue water, whichis one of the reasons rate increases are difficult for some customers toaccept.
“Water infrastructure is usually out of sight and out of mind forconsumers,” Hoffbuhr adds. “But to prevent today’s water infrastructure concernsfrom becoming tomorrow’s crisis, we must better communicate the value of waterservice to communities. We need to talk about the value of public healthprotection, and also the fact that water is the lifeblood of any community byproviding fire protection, economic development and quality of life.”
Ifthat’s true, then the lifeblood in many communities across North America is inpretty bad shape. Pipes laid between the beginning of the 20th century and the1950s are in desperate need of either maintenance or replacement. Experts sayonce a pipe reaches its 50-year mark, it’s much more susceptible to leaks andbreaks. And now more than ever, water utilities are receiving complaints aboutred water, taste, odor, turbidity and reductions in pressure and flow.
“There are many studies and reports that indicate water distributionsystems, as a whole, are in horrible shape,” says Piero Salvo, president of WSATrenchless Consultants Inc. “But what seems to still be holding back the amountof water main rehab being done, regardless of the method being used, is the lackof funding. That issue always seems to be the one to slow any workdown.”
A recent AWWA report concluded that more than $250 billion over 30years will be required nationwide for the replacement of drinking waterinfrastructure. But the approach to the problem is still under debate. With amore difficult set of roadblocks than wastewater — such as pressure retention(approximately 150 psi in the United States), reconnection of services andmaintaining quality standards — more modern technologies such as trenchlesstechniques are much slower to gain acceptance. But as water utilities throughoutNorth America are challenged with more costly water-related issues, a widerrange of options for repair or replacement are being examined.
“Thewater industry has seen the sewer industry evolve rapidly. And with the pressurethat water companies are getting from the citizens and a number of othersources, they are really trying to maximize their dollar as well,” Smithexplains. “The owners are not satisfied with the status quo anymore. So you aregoing to see a very rapid increase from conventional dig-and-replace methods,shifting over to trenchless technologies to rehabilitate and replace watermains. And I think it’s happening right now.”
The Trenchless Options
Methods oftrenchless rehabilitation are distinguished into structural and non-structuralcategories. Non-structural solutions are used when the host pipe is deemedstructurally sound and the only problems that the distribution system hassuffered are colored water, lower pressures and taste issues. Structuralmethods, however, are required when the host pipe is considered to haveinadequate structural capacity or if the main being rehabilitated has suffered aseries of breaks.
Structural methods of rehabilitation includesliplining, pipe bursting, cured-in-place pipe (CIPP) and horizontal directionaldrilling (HDD), while cement mortar and epoxy liners are all considerednon-structural. According to experts, non-structural solutions represented theonly real market for trenchless methods for quite some time — with cement mortarlining and epoxies gaining a reasonable amount of acceptance in waterapplications.
“When you have poor quality or poor hydraulics, it’s anon-structural problem, so all you really need to do is thoroughly clean thepipe and put in a new coating — whether it’s with cement mortar or an epoxylining,” explains Joe Loiacono, director of business development for SanexenEnvironmental Services, Quebec, Canada. “Since these liners are very thin (1 or2 mm thick), there is no reduction in diameter and it actually improves your[flow characteristics]. Your hydraulics are improved and it stops the occurrenceof tuberculation afterward, so you get a clean pipe for a long time — if not therest of its life.”
As the first real “trenchless” method of water mainrehab, cement mortar lining was originally used as far back as the 1950s.Equipment and materials have improved dramatically over the years to create amuch more reliable end-product. By the early 1990s, the amount of cement mortarlining work had increased dramatically. Epoxy liners have also been known to bea good fit for water mains, because the epoxies used for potable water linesmust be NSF 61 approved.
While non-structural methods have representedthe majority of the trenchless water market, structural technologies arebeginning to exhibit more potential as well. Once a main is properly installed,owners don’t have to worry about that pipe for a long period of time. The mostpopular structural method thus far has been CIPP, which experts believe willmake a significant impact in the near future.
Because of this, pipebursting, sliplining and HDD have all met with only moderate success on thewater main replacement end. In the 1990s, several projects were done with bothpipe bursting and sliplining in western parts of the United States and Canada.But they were never done in a magnitude that could be called a market, soprojects were only completed based on an as-needed basis.
Keys to Acceptance
In addition to NSF 61approval requirements, which are the nationally recognized health effectsstandard for all devices, components and materials that contact drinking water,another significant deterrent for structural trenchless solutions has been theneed for localized excavation to reinstate the services.
“One of thekeys to water main rehab is the reinstatement of services from the inside,” saysLoiacono. “The obstacles to all of this water main rehab was the reinstatementof services — owners would have to dig them all up. With pipe bursting orsliplining, you would have to dig at every service. If you have a service every30 or 40 feet, you would have to almost dig up the whole street, so we might aswell dig up everything.”
According to experts, the ability to reinstateservices from the inside of the pipe allowed more structural rehabilitation toreally start to take off. Experimentation of these technologies started in themid-1990s. The products that came about really started taking off in 2001,quickly perking interest for CIPP and opened the realm of possibilities for pipebursting and sliplining. The technology, such as what is used in Sanexen’sAqua-Pipe, uses a remote-controlled mechanical robot (equipped with a camera anda closed-circuit television unit) to open and close service connections.
Thus far, a majority of municipalities and owners have opted fornon-structural lining technologies, believing they will save money and be ableto accomplish more footage for the same cost as to replace, in addition tolessening inconveniences to homeowners or businesses. Cement mortar lining isstill leading the way, while epoxy resins now provide near-perfect adhesion tothe carrier pipe. So with a wide variety of reliable, unobstrusive andcost-effective trenchless technologies for both structural and non-structuralneeds, municipalities should have all the options they need — to bring drinkingwater quality up to where it should be.
Currently, there are still avariety of factors affecting the progress of trenchless methods. Cost-savingsand reduced disruption are the leading factors for selecting a trenchless optionover an open-cut replacement. Unfortunately, what continues to prohibit moretrenchless work comes down to somewhat of a Catch-22.
“The owners havebecome more aware of the trenchless options available to them, but sometimesthey might feel that there have not been enough completed projects to make themfeel at ease in using a trenchless method,” Salvo notes. “But carrying outsuccessful installations helps speed up that process, because one bad projectcan leave a bad taste for a long time, hence the importance of QA/QC [QualityAssurance and Quality Control] for each one.”
Nick Zubko is associate editor of Trenchless Technology