Water & Trenchless
Eighty percent of the world is covered by water; however, only 1 percent of that is considered fresh water and available for human consumption. You would think that with those percentages, water infrastructure would be near the top of the list when it comes to spending money to keep the taps flowing. But year after year, cuts are made in available money for water and sewer infrastructure.
Americans tap into an estimated 341 billion gal of water every day. According to the American Water Works Association (AWWA), there are approximately 54,000 community water systems in the United States, providing about 90 percent of Americans with their tap water.
Does the public realize the state of the water infrastructure in their communities? Experts say, it’s that old saying, “Out of sight, out of mind.” As long as the water flows from the faucet or shower, there’s good pressure, no odor or bad taste, then everything is good. However, with each passing year, the condition of those pipes — many constructed 100-plus years ago — continue to deteriorate and need attention by municipalities too strapped for cash to pay for it.
“But it is unfortunate that the public will only pay attention and cry out when events such as pipe breaks, leaks, loss of pressure and flow and contamination affect them directly,” says Joe Loiacono, director of business development for Sanexen Environmental Services, Quebec, Canada, which manufactures Aqua-Pipe for the structural rehabilitation of 6- to 12-in. water mains. “Even then, once the problem is fixed, they generally return to their complacent nature.”
In talking with people in the water industry, there is a general consensus that the state of the water infrastructure in North America is in dire need of maintenance and/or replacement; words to describe the systems include “neglected” and “poor.” For all the attention that our water infrastructure warrants, municipalities, which are turning to trenchless more and more with regard to their sewers, are hesitant to employ trenchless technologies when it comes to their water systems. The reasons for such a tepid response to trenchless and water include its cost-effectiveness and concerns with water quality and capacity — areas the trenchless industry must market better for the technology to gain acceptance in this important market.
Why Not Trenchless?
Seattle Public Utilities (SPU) provides drinking water to a 1.3 million population, with about a 50-50 split between retail service and water districts and cities that it wholesales the product to. It is responsible for 1,800 miles of water pipe and 1,600 miles of sewer. SPU’s capital improvement (CI) program for drinking water alone is approximately $100 million per year, with its entire CI budget totaling $150 million.
Scott Haskins, a SPU deputy director, notes that some of the Seattle infrastructure is more than 100 years old, with a majority of the pipes around 40 to 50 years old — not at all unlike most cities in North America. While various trenchless technologies are regularly utilized to address its sewer issues, the same cannot be said on the water side.
“As far as drinking water goes, there has been relatively little use of trenchless technology,” Haskins says. “I think we are interested in seeing the technology investigated, researched and basically further evaluated in its cost-effectiveness on the drinking water side, but the application has been less here.” Seattle has done some sliplining work on its larger diameter water pipes, but Haskins says for the smaller diameters, the cost-effectiveness of the technology comes into play.
“We’re not ruling out [trenchless technology] on the drinking side but we’re just being more aggressive on the sewer mains,” he says.
Seattle is not different than most cities. The City of Boston, for example — one of the more aggressive and progressive trenchless cities in the United States — limits its use of trenchless on the water side to primarily cleaning and cement mortar lining, as well as some sliplining.
Trenchless Options
Methods of trenchless rehabilitation are categorized as either structural or non-structural. Non-structural solutions are used when the host pipe is deemed structurally sound. The only problems that the system is experiencing include colored water, lower pressures and taste issues. Structural solutions are required when the host pipe is considered to have inadequate structural capacity or if the main has suffered a series of breaks. Structural methods include sliplining, cured-in-place pipe, pipe bursting and horizontal directional drilling. Cement mortar and epoxy liners are considered non-structural methods — and are the only methods, quite frankly, that have represented the trenchless market on the water side for many years.
“It is ironic [about the lack of more trenchless usage] because trenchless started in water,” says Dan Ellison, an engineer with Boyle Engineering, Ventura, Calif., and chairman of the AWWA Water Main Rehabilitation Committee. He has written several books on trenchless technologies, including one on cleaning methods for water pipes and is in the process of finishing another on how to re-connect services when a no-dig or low-dig method of rehabilitation has occurred.
“The oldest methods are cement mortar lining and epoxy lining, with cement mortar lining dating back to the 1930s,” Ellison says. “A lot of pipes have been done with those methods but the others are still trying to get traction in the water industry. These include pipe bursting and tight-fit lining using HDPE and PVC.”
Ellison — a strong proponent of trenchless methods — believes cost is the primary reason working against trenchless on the water side. He cites three reasons: 1) holes generally must be excavated at each service connection so the laterals can be reconnected; 2) bypass systems must be installed to supply customers throughout the construction period; and 3) manholes do not exist that provide ready access to the main to install the liner.
“So when you add those three things up, trenchless systems don’t look that much cheaper. I think they are, but they don’t have a clear cost advantage like they do in the sewer industry,” Ellison says.
Haskins, also a trenchless proponent, concurs, but adds in the factor of fear by the municipalities. “I think it is basically economics, but I also think there are some issues of material used, and I think there have been some improvements there. Some of it has been past conventions and people’s familiarity of what they have always done.”
He notes that SPU is in the middle of a pilot project to reline some water lines, in lieu of replacement, in a major neighborhood in the city. SPU will be evaluating all aspects of the project once it’s done — from economics to water quality to capacity.
What Needs to Be Done
Loiacono says the trenchless industry needs to step up its efforts to show the benefits of the technology to the water side — in similar fashion as it did with the sewer side. “We need to repeat what was done for the sewer market with regards to awareness, standardization, training and R&D, while placing great effort in reaching the individuals in the water departments and agencies and the consulting engineers.” The trenchless associations also need to partner with organizations such as AWWA to get the information out, he says.
Loiacono says the water market is as important to the industry as the sewer side and makes this analogy: “If the human body was compared to the trenchless technology market, the sewer and water markets would be its heart and arteries, in no specific order … The water market potential is just as great, if not greater than the sewer market. In addition, the R&D from one market will benefit from the other and vice versa.”
Ellison agrees that the potential is definitely there. “I think there is a huge potential,” he says. “And it’s gaining but it’s gaining slowly because of the technical challenges, such as the need for a bypass system and reconnecting services … Education and awareness will help and better technology will definitely help.”
Ellison notes that an AWWA Research Foundation Report is expected to be released in late summer, which will address developing no-dig and low-dig methods to reconnect services and will cover use of keyhole technology and robotics.
Haskins says that more education is needed about what trenchless can do for water infrastructure but believes it will catch on in time. “I think it has a strong future,” he says. “I think it’s the direction that things are going to be heading. I don’t think that cut-and-cover is the approach … It’s more disruptive in a number of ways and it impacts the public more. Seattle is definitely moving down [the trenchless] path.”
Loiacono believes the advent of asset management programs will help cities develop structured short- and long-term intervention plans that will show where trenchless technologies can be best utilized. “The use of trenchless technologies would allow municipalities to rebuild the asset value of their system, extend its life and rehabilitate the water mains without mass excavation and customer impact,” he says.
Sharon M. Bueno is managing editor of Trenchless Technology.