Trenchless Pipe Relining Continues to Thrive

The trenchless pipe relining market has come a long way since it was first used to mend a section of a London sewer back in 1971. First viewed as a premium process — and viewed by some with suspicion — pipe relining has become a mainstay within sewer systems across North America.

While pipe relining — notably sliplining — has roots predating the 1970s, it was the invention of the cured-in-place pipe (CIPP) method — the “Insituform” process — by Eric Wood that fueled the growth of the trenchless rehabilitation market. Wood and his company, Insituform, completed its first U.S. installation in 1976 and were granted a U.S. patent for CIPP in 1977, planting the seed for market growth. The expiration of the patent in 1994 led to new entrants into the marketplace and increased competition.

Of course, the technology itself matured over the years, too. It was also about this time that we began to recognize the need to re-invest in our infrastructure that was beginning to show its age. Landmark publications like the Water Infrastructure Network (WIN) report (2000) and the EPA Gap Report (2002) began opening ours eyes to the problem by documenting multi-billion dollar needs in water and wastewater investment. According to Global Water Intelligence (2009), the global pipeline rehabilitation market exceeds $8 billion, and was expected to top $10 billion by 2016 (the CIPP spending was estimated at $1 billion).

As a result of the convergence of technology and opportunity, the trenchless relining market has flourished, even remaining strong through the worldwide economic recession in 2007-2008. Throughout most of its history, trenchless pipe relining, including CIPP, has been strongly linked to gravity sewer applications. And while that market outlook remains strong, new developments in trenchless relining methods are also emerging.

Here, we take a look at some of the developing trends within the trenchless relining market. In brief, they include: applications outside of the traditional gravity sewer market and the continued evolution of pipe relining methods.

Relining Market Overview

A recent informal survey by Trenchless Technology (a sister publication of Utility Contractor) showed that a majority of utilities across the United States are routinely using trenchless relining methods. Of the utilities polled, 84 percent claim CIPP as the most common method, and industry experts agree there have been several significant developments in CIPP and across the pipe relining market.   

Some of the major innovations in pipe relining have taken place in CIPP work, and according to the Trenchless Technology survey, it remains the preferred method. Industry-wide, it is estimated that CIPP has been used to rehabilitate more than 35,000 miles of pipe since the early 1970s.

The biggest changes in CIPP work have been in technological advancements and improved procedures, production and equipment, according to Dave Fletcher, National Sales Manager for Applied Felts.

“While it has a successful and proven track record of high performance and impressive design life, until now CIPP applications have primarily focused on gravity lines that use traditional felt liners,” he said. “All of that is changing rapidly with new and exciting innovations in this market being designed to rehabilitate pressure pipes, potable water and lateral sealing. CIPP can accommodate modifications to traditional applications because of its flexibility, structural components, corrosion resistance and economic advantages.

“Manufacturers like Applied Felts are answering the call for liners that are stronger, thinner and can withstand the high internal pressures required for pressure pipe applications. Liners reinforced with fiberglass blend the properties of felt and fiberglass to create liners that are stronger than ever before. In addition to added strength, the liners are typically thinner than traditional liners so they deliver significant resin savings and can lower overall material costs. Custom combinations of liner, resins and coatings help to create CIPP applications for even the most challenging rehabilitation projects.”

Steam-cured CIPP is the predominant method of installation in the United States due primarily to the fact that it allows for faster installation times. But there are other methods available, including UV-cured pipe, which is popular in Europe.

UV Curing

In the United States, Reline America and Saertex are two leading suppliers of UV-cured products and services. Despite the fact that it is still in its startup phase in the U.S. market, UV is gaining acceptance.
“The UV market is growing well and steadily,” said Reline America President Mike Burkhard. “We have installed nearly 2 million lf to date, and our contractors just installed a 54-in. diameter, 400-ft  long shot in record time. Our municipal installers will have installed approximately 100,000 lf by the end of this year.”
As with other methods of lining, technical improvements are being developed to improve the efficiency of UV-cured CIPP. “We are currently testing a product that will include an attached inner veil for greater abrasion resistance and increased flexural properties by 25 percent over our current liners,” Burkhard said.
“New ancillary equipment breakthroughs, especially for large diameters, have enabled faster liner installations. We are in the final stages of building our first 2,000-watt curing system to add more speed and greater depth to the curing process. We have steadily increased the quality aspect of installations through product development that has allowed the installation process to be more machine driven, which was all done in-house.”

Some of the advantages of UV over traditional curing methods include increased automation, less environmental impact and improved structural characteristics, Burkhard said.

Culvert Rehab

Another area of growth for the trenchless relining market is for rehabilitating culverts that were constructed to divert storm water under newly built roadways. Like municipal water and sewer systems, these culverts were built in the post-war years as America began to expand rapidly and are in need of repair. Culverts represent an area in which trenchless methods are still in the early stages. In fact, part of the problem is identifying where the culverts are and what condition they are in, said Mohammad Najafi, a Professor at the University of Texas-Arlington and Director of the Center for Underground Infrastructure Research and Education (CUIRE).

“The industrial growth during 1950s marked a rapid development in construction of high-speed, high-capacity roadway infrastructure,” Najafi said. “Today, the United States has 3,981,521 miles of roadway. During the construction of these roadways, millions of culverts were installed under them. The philosophical saying, ‘out of sight is out of mind’ applies as more importance has been given to preserving the physical infrastructure on the surface like roadway, pavement, bridges, guardrails, etc., than underground infrastructure. Various theories, models, frameworks and management plans are developed to track, inspect, maintain and repair the surface infrastructure. However, the invisible critical components of culverts have been neglected.

“The location and condition of these pipes comes to notice only when there is a problem such as settlement or complete failure of a roadway. The deterioration of culvert pipes and other components is a growing problem for transportation agencies. The deterioration of pipes because of their increasing age or change of service conditions, such as increasing flow due to changing watershed conditions, increases the wear and tear of these pipes. Various structural, hydrological, environmental and economical (lack of proper maintenance) factors, may accelerate the deterioration process.”

The Michigan Department of Transportation — a member of CUIRE — estimated that there are 200,000 culverts in the state. If that number is typical for other states and populations numbers, that means there are in excess of 6.5 million culverts across the county.

Culverts, however, pose some challenges that are quite different from gravity flow pipes in municipal settings.
“The variety in material types, shapes, backfill materials, types of roads located above and environmental conditions make every single culvert unique in terms of its behavior and durability,” Najafi said. “There have been many studies in order to identify the key parameters affecting culvert behavior, but the success rate in providing standard solutions to the problems remained to be low. Had the culvert behavior been completely understood, it would have been much easier to manage the culvert inventory by timely renewal and repair efforts. Wide geospatial distribution of drainage infrastructure assets further complicates the management of these assets. Therefore, the first and most important step in the culvert asset management procedure should be the establishment of a database consisting of asset inventory and asset condition information. By monitoring this database, the Department of Transportation officials will be able to identify the critical culverts before failure and to take necessary steps in a timely manner to repair, rehabilitate or replace them.

“Culverts are open ended and sometimes bypassing flow is more difficult than gravity sewers. Additionally, they might be hard to reach and the lengths are short. In the majority of cases, the access points are difficult to find due to vegetation and soil deposits. One further difference is that culverts are shallow compared to gravity sewers, and they take heavy traffic loads.”

CIPP lining is popular for rehabilitating culverts, but many other methods are used, including sliplining, spray-on linings, spiral wound and panel lining.

Centrifugally Cast Concrete Pipe (CCCP)

Various pipe coatings have been available in the marketplace for some time and are starting to gain momentum, according to Bill Shook, President of AP/M Permaform, which offers the CentriPipe CCCP system.

“The technology of vertical centrifugal spray casting has been used for decades for lining manholes,” Shook said. “Basically, CCCP uses its bi-directional ‘SpinCaster’ to apply uniform and densely compacted layers of cementitious material to the inside of failing sewers, creating a new, structurally sound, joint-free, waterproof pipe that adheres tightly to the original pipe.

“[CCCP] is as an extremely versatile and effective solution for most trenchless large-diameter, storm or sanitary sewers where the rehabilitation must be trenchless, structurally sound and optimize flow capacities. The fiber-reinforced materials developed by AP/M Permaform have high tensile strengths, cure quickly and stick to a variety of materials including CMP, cast iron, steel plating, brick and clay. It can be used in pipes 36 in. and larger and can be applied to round, arched, box, elliptical and other odd-shaped pipe.”

Looking Forward

UV lining, culvert rehab and CCCP are just a few of the areas within the trenchless relining market that are gaining momentum and present market opportunities going forward. Lateral and manhole rehabilitation and water main lining have been at the forefront of the trenchless market for a long time now, but we are just scratching the surface on the work to be done in those areas. Additionally, the renewal of force mains is becoming a greater need across the country as these vital links are aging just like the gravity flow sections.

“The ASCE Report Card states that addressing the nation’s sewage collection infrastructure needs may require an investment of more than $300 billion over 20 years,” Shook said. “Similarly dire assessments apply to the underground pipes and culverts that divert stormwater. Replacing and rehabilitating America’s underground pipes is an ongoing challenge that will continue for the next several decades.”

The trenchless relining market has grown steadily over the last 40 years, and with new markets and technologies emerging, it promises to grow over the next 40 years and more.

Jim Rush is a Contributing Editor of Utility Contractor.