The Sahara platform is a tethered inspection tool for assessing pressurized water and wastewater pipelines six inches and larger. The platform detects leaks and gas pockets, collects visual condition, and maps pipelines in a single deployment, without disrupting regular service. With this condition assessment data, pipeline owners can make informed rehabilitation and management decisions on a pipe-by-pipe basis.
The SmartBall platform is a free-swimming inspection tool used to detect leaks and gas pockets and map pipeline networks. This platform assesses pressurized water and wastewater pipelines in a single deployment, without disrupting regular service. The SmartBall platform provides utilities with pipeline condition data to make informed rehabilitation and management decisions on a pipe-by-pipe basis.
The PipeDiver platform is a free-swimming pipeline condition assessment tool that is easy to deploy and operates while the pipeline remains in service. This tool provides utility owners with pipe wall condition data used to make rehabilitation and management decisions on a pipe-by-pipe basis.
Utilities can save their communities substantial amounts of money, reduce the need for unaffordable rate increases or financing arrangements, and improve the environmental sustainability of their operations – all while maintaining and enhancing system control.
Around the world, critical valves are in poor repair, or even inoperable. When critical valves fail, managers have effectively lost control of their system, increasing vulnerability to water main breaks or any other system hazard. Once valves have failed, utilities have traditionally sought to replace them, often at great cost, both in terms of time and expense.
But what if there were another way? It turns out there is a far more economical, less risky, and more sustainable option: preventative maintenance, repair, and rehabilitation. High performing utilities are turning away from the wasteful practice of replacing valves that can be restored to full function, instead engaging experts in asset renewal to extend the life of those assets at a substantially lower cost.
With advancements in technology and a willingness to develop proactive pipeline integrity programs, utilities can successfully reduce failures, mitigate risk, reduce capital expenditures, and increase confidence in the overall operation of their force mains.
New standards of best practice for force main management involve a variety of methods and technologies to provide data and information with which to make decisions. Utilities can now often perform a detailed condition assessment while the force main remains in service.
There is no “one-size-fits-all” way of assessing force mains. Any approach should be tailored to risk tolerance, material, diameter and past failure history. Savvy utility managers are turning to programs that reduce damage to assets, prioritize investment to minimize community impact of asset failure, and reduce the consequence of failure by enabling system control.
Cast Iron Pipe (CIP) accounts for nearly 40 percent of the water pipes in the United States and are mostly between 50 and 110 years old (source: EPA, 2009). Because of the brittle nature of Cast Iron, these pipes typically crack and leak before they fail and data collected from over 10 years of inline leak detection surveys has found that Cast Iron Pipes have the highest rate of leaks per miles surveyed of any pipe type. Because of how and where it fails, leak detection is an effective and proactive method of condition assessment on Cast Iron pipes.
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Today, new advancements in technologies and data analytics are helping utilities build asset management programs using a risk-based approach to pipeline condition assessment with the lowest financial impact.
There is no one-size-fits-all approach to assessing metallic pipelines. An approach should be tailored within the context of your risk tolerance while taking into consideration the material, diameter, and past failure history. Many different methods and technologies can be combined to provide data and information to make decisions and prioritize pipelines. The approach can range from do-nothing to a full in-line inspection making targeted repairs and be progressive in nature.
On Thursday May 17, thought-leaders, leading utilities, and other industry experts, came together for Xylem’s Modernizing Water Infrastructure Workshop in Laurel, MD. Like Infrastructure Week, the event served as a platform for innovators to connect, discuss, and inspire water industry professionals to solve the problems associated with managing water infrastructure. If you were unable to attend, here are some of the highlights of the day.
From Manure To Modern
The morning session focused on utilities, and began with a keynote presentation from industry visionary, George Hawkins, who provided an energetic analogy on how the manure crisis of the 1800s compares to our current water crisis. While the common person only saw the problem of horse manure, the engineers of the 1800s saw the potential for change and created the car, which eliminated the problem while increasing productivity and reducing costs. That’s what we, as an industry, need to focus on as we modernize water infrastructure — seeing the potential for greatness and improvement through innovation.
Hawkins went on to discuss how we report efficiency. If everything is measured in a productivity approach, seeking additional funding becomes easier. Money has gone farther than ever before in the water infrastructure industry because of the advancements in technology that allow us to work more efficiently and accurately. People are prepared to invest in something that matters to them, especially when they understand that the current monies are going further, and you can prove it. Listen to part of Hawkins’ presentation:
100 Years of Continuous Improvement
Following Hawkins’ passionate keynote address, we heard from Glen Diaz, Division Manager of Water/Wastewater Systems Assessment at WSSC. As WSSC (Washington Suburban Sanitary Commission) celebrates their 100-year anniversary, Diaz reflected on the advancements in technology through the years.
Even in the past 10 years, things have greatly improved in the water industry. Diaz cited the 66” water main break in Bethesda, MD in 2008 and how current technology can aid in preventing future incidents. Diaz went on to discuss how most PCCP failures are due to broken wires and how noisy pipes are typically problem pipes.
However, now, WSSC workers receive mobile alerts, through the implementation of Pure Technologies AFO system, as soon as wire breaks occur so they can address any cause for concern. This system has already helped WSSC avert 20 failure events to date, a $21 million dollar savings on the conservative side! See Diaz’s presentation here:
With Challenge, Comes Major Opportunity
After hearing from WSSC, we heard from Jody Caldwell, Asset Management Director for Great Lakes Water Authority (GLWA), on building an asset management program from the (under) ground up.
Caldwell began with an overview of some of the organizational challenges GLWA is experiencing being a relatively new utility. He talked about the process GLWA went through putting together a 10-year strategic roadmap focused on continuous improvement to overcome the challenges and build a utility for the future. Caldwell went on to discuss GLWA’s pipeline risk management strategy, which uses a quantitative, risk-based analysis to drive decisions. This tiered approach allows them to easily calculate their risk return on investment and ultimately, become a best-in-class pipeline management system. Catch the end of Caldwell’s presentation, as well as the Q&A session.
Extreme Preparation for Extreme Weather
After a brief networking break, there was a roundtable discussion that focused on how leading utilities dealt with the extreme weather conditions this past January. The roundtable featured (from left to right) Joseph Mantua, Deputy General Manager Operations at WSSC; Carlos A. Espinosa, Chief of the Office Of Asset Management at Baltimore City Department of Public Works; and Buddy Morgan, General Manager at Montgomery Water Works (Alabama). Who said the South doesn’t experience cold weather.
The discussion began with the question, “Were there particular pipe materials you found to be problematic during the extreme winter, and if so, what were they?” For the City of Montgomery, AL, cast iron mains had the most problems. Baltimore City was no different, reporting that 98% of the water main breaks were in cast iron pipes, the majority of which were 12” or smaller. WSSC confirmed the cast iron trend, with the majority of breaks occurring in 6 or 8 inch diameter pipes.
In order to prepare for next winter, the utilities agreed for the need to ensure that all their equipment is in working order ahead of time, and have conversations with their crews and contractors to make sure they’re prepared to respond, and recognize the need for additional support services and how to best utilize them. Additionally, the panel agreed that social media played a crucial role in real-time communications with customers, aiding them in being proactive with the media, and helping to communicate status updates. Watch the beginning portion of the roundtable discussion:
The discussion moved on to how to keep employees engaged during extreme weather conditions. Aside from the generous overtime benefits, WSSC brought hot meals to workers, while Alabama Water Works limited hours per week to 65 with 24 hours off before coming back. They also held celebratory cookouts once the weather warmed up.
Be Best-In-Class
After lunch, the afternoon sessions focused on technologies and management best practices. Pure’s very own Mike Higgins, Senior Vice President, Americas, talked about buried infrastructure philosophies utilities can use to manage their most valuable assets. Mike kicked-off his presentation by sharing statistics from the 2017 Infrastructure Report Card from the American Society of Civil Engineers (ASCE).
Following these eye-opening numbers, Higgins shared his insights on success for professionals in the water industry.
Key questions utilities need to answer include:
Typically, the answers should focus on one or more of the following areas:
1) Averting pipeline failure
2) Reducing pipeline risk
3) Extending the life of an asset
4) Increasing sustainability
5) Optimizing CAPEX/TOTEX (capital/total expenditure)
Higgins then shared his secret recipe for the 10 key ingredients to be a best-in-class utility:
1) Focus on operations excellence
2) Coordinate with all key stakeholders
3) Perform necessary Public Relations
4) Create a clearly defined team across departments and disciplines
5) Always aspire towards total pipeline management
6) Prepare for emergencies, they will occur
7) Be opportunistic
8) Continue to innovate
9) Understand limitations of innovative approaches
10) Keep your boots on the ground (maximize the amount of inspected pipe)
He concluded his presentation talking about the importance of monitoring key performance indicators (KPIs) and keeping senior leadership engaged. Watch Higgins’ presentation:
The 4th Industrial Revolution
Richard Loeffler IV, Client Solutions Architect at Emnet, then reminded us that the number one criteria for where cities locate is the access to water. Loeffler also stated that we are in the midst of a 4th industrial revolution—IoT (Internet of Things) is changing the way we live, work, and play, and is transforming the fundamental economic cost structure of water and related civic works.
He used the example of South Bend, IN, to illustrate just how effective IoT and RTDSS (real-time decision support systems) can be. Ultimately, it’s all about environmental stewardship — it’s not just about saving money, but about doing the right thing for the world that we live in. View Loeffler’s presentation:
Smart Water
Following Loeffler’s informative presentation, Bridget Berardinelli, VP Product Management And Continuous Improvement for Xylem, stated how smart meters and applying analytics can help utilities generate real results. Berardinelli began by explaining how Sensus develops advanced technology solutions that enable the intelligent use of critical resources.
She covered Advanced Metering Infrastructure (AMI) and explained how to leverage it in order to increase operational efficiencies and improve scalability and flexibility. By delivering machine learning and analytics using a programmatic approach, Sensus is able to inform operational interventions that transform how water utilities operate. View her presentation:
Our Newest Solution
Concluding Berardinelli’s presentation, we heard from Pure Technologies Area Regional Manager, Susan Donnally, on how to manage large diameter water transmission mains. She began her presentation with a discussion on pipeline risk prioritization, stating that using data to drive decisions is a quintessential part of moving towards a proactive asset management approach. She then dove into why pipes fail; noting that age alone is a poor indicator of pipe condition. While there is no singular technology that can identify all of the indicators of pipe deterioration, a holistic, risk-based approach can help.
Donnally then moved on to highlight some of Pure’s latest technology innovations:
Additionally, Donnally had a huge reveal! She introduced Pure’s newest PipeDiver solution, the PipeDiver UltraTM (currently in the beta testing phase with a couple of clients), which features high-resolution wall condition information for metallic pipes, such as cast iron, ductile iron, and steel, and is as easy to deploy as the existing PipeDiver. Watch her presentation:
You’re Not Going to Start with Perfection
Vice President of PureAnalytics, Travis Wagner, gave the final presentation of the day on managing distribution systems.
He truly engaged the audience by asking attendees to raise their hands if:
Not surprisingly, most hands were raised! From there, Wagner went on to urge everyone to update their approach.
Utilities need to start asking themselves the following questions:
Wagner concluded this portion of the presentation with a quote that all utilities should follow: “You’re not going to start with perfection, the goal is to build toward becoming better.”
Next, Wagner moved on to discuss risk management, consequence probability analysis, data collection, and risk mitigation. It was truly an eye-opening presentation:
The day concluded with demonstrations of all the latest technology available to utilities, including a 108” PipeDiver, SoundPrint® AFO system, Sensus meters, Visenti software demos, not to mention some great networking.
Want to learn more about our Modernizing Water Infrastructure Workshop? Check out #H2018Workshop on Facebook, LinkedIn, and Twitter.
Inspection required divers to retrieve PipeDiver tool from piping outlet located 40 feet beneath the Atlantic Ocean.
For the Township of Ocean Sewerage Authority, proper planning, quick thinking and late night tool modifications keep critical pipeline inspection on track and on schedule.
As every utility manager knows, a critical pipeline inspection can be temporarily derailed for unanticipated reasons. Especially when the assumed pipeline turns out to be composed of a completely different material, with a smaller than expected internal diameter, all of which could affect the condition assessment methods.
If you’re the manager under a time-critical deadline, you face pressure to resolve the issue and successfully move the inspection forward.
Fortunately, with proper planning, quick thinking and an experienced mobilization team in place, an unforeseen challenge like this can turn into an opportunity to gain a better understanding on the state of your linear assets.
Pipeline broken up into 4,000 foot and 2,000 sections by a drop manhole.
Project background
In November 2016, Pure Technologies (Pure) was contracted by Hazen and Sawyer (Hazen), consultant to the Township of Ocean Sewerage Authority (TOSA) in Oakhurst, New Jersey, to conduct a non-destructive evaluation of TOSA’s 36-inch diameter Ocean Outfall Pipeline constructed between 1966 and 1968. The pipeline was (supposedly) a 1.1 mile steel pipe that carries treated effluent to diffuser piping located 40 feet beneath the Atlantic Ocean.
TOSA had sought Hazen’s assistance in exploring ways to help them better understand the wall loss condition of their outfall pipeline in order to evaluate the need for repairs and or reconstruction options using the inspection data.
Prepping the PipeDiver tool for the electromagnetic inspection.
Understanding the pipe material determines inspection methods
In addition, the line is broken up into 4,000 foot and 2,000 foot sections by a drop manhole. According to profile assumptions, the Ocean Outfall Pipeline was thought to be steel. Understanding the pipe material is an important step in the selection and justification of condition assessment methods.
Based on the assumed steel material, Pure recommended the free-swimming PipeDiver® tool to deliver electromagnetic technology for the inspection method. The PipeDiver tool is equipped with Pure’s proven electromagnetic technology, which can be used on metallic pipe materials such as steel and ductile iron to detect cylinder corrosion. Electromagnetic sensors also provide the location and an estimate of the area and depth affected.
“This assessment using the latest in-pipe inspection technology, provided TOSA significant value in cost savings and avoided unnecessary public disruption, all while providing a better understanding of their infrastructure for the long-term management of their ocean outfall. With this understanding comes peace of mind in knowing that the most economical and effective in-kind replacement will be implemented to ensure long-term reliability of this vital asset.” William S. Gettings, P.E., MBA, BCEE, Senior Associate and NJ Office Manager Hazen and Sawyer
Two models of the free-swimming PipeDiver tool were assembled to inspect the various pipe materials, one for steel, the other for PCCP.
As a precaution, two models of PipeDiver tool assembled
Different PipeDiver tools are used for assessment of different pipe material. The optimized 24-detector PipeDiver tool uses electromagnetic technology to locate and identify steel pipes that have indications of wall loss, while the 6-detector PipeDiver tool is designed to identify PCCP pipes that have indications of broken wire wraps, the leading indicator of problematic pipe.
While it was known that the 2,000-foot (Section A) was made of steel pipe, there was no definitive information on the 4,000-foot (Section B) of pipeline material. In response, two models of the PipeDiver tool (a 24-detector tool for steel and a six-detector tool for PCCP were brought on site, assembled and balanced).
The metallic PipeDiver was run through Section B, where data determined that the section was not steel pipe, but rather PCCP, with a small section of cast iron pipe.
That was good call.
Getting the PipeDiver tool ready for the first insertion.
Sections of pipeline 3 inches smaller than anticipated
During the planning stage, it was thought that the pipeline had a 36-inch internal diameter. However, it became apparent after seeing some highly anomalous data sets from the 24-detector PipeDiver tool that the internal diameter was at least 3 inches smaller, which was confirmed at both the inlet and outlet by direct measurement using onsite divers.
This necessitated some late night heroics from Pure’s analysis group, research and development and on-site staff to modify the neutrally buoyant tool to fit into the smaller pipeline.
From here, the inspections went off without a hitch.
In the end, multiple PipeDiver runs were performed over the five-day inspection. On Section A of the steel pipeline, three pipes displayed anomalies indicating wall loss from 30 percent to 50 percent. One pipe contained a single location of wall loss, while two pipes had multiple locations of wall loss.
Analysis of the PCCP data obtained during the inspection determined that one pipe section in Section B displayed an electromagnetic anomaly consistent with five broken wire wraps, and one anomalous signal shift that could be caused by an undocumented feature or a change in pipe property.
A beautiful way to end a successful inspection.
TOSA has a better understanding of their linear assets
Pure worked closely with Hazen and TNJ Marine, Inc. throughout the inspection. It was recommended that a portion of Section A undergo replacement due to pipe sections with anomalous electromagnetic signals, apparent pipe wall degradation and visible wall loss anomalies. In addition, where five wire breaks were found, it was recommended that a 16-foot length of 36-inch PCCP including plated access port within a sealed access manhole be replaced. Finally, it was recommended Section B undergo re-inspection within the next five years to monitor existing damage and re-evaluate the pipe section with anomalous signal.
All in all, a successful inspection despite the many challenges.
Nothing grabs headline news like the failure of a rising main, which can be extremely damaging to the environment and harmful to a utility’s reputation.
Historically, wastewater rising mains have been difficult to manage, especially those made with ferrous materials, where the failure method is slow when compared to concrete pressure pipe. As well, sewer rising mains have special operational challenges that don’t apply to gravity sewer mains as they typically cannot be taken out of service for inspection, and due to the presence of solids in the fluid, rising mains represent a far more abrasive environment than potable systems such that assessment methods for water mains may not be applicable.
The presence of pockets increases the potential of corrosion in metallic pipes.
The primary failure mechanism of ferrous rising mains is due to internal corrosion. Gas pockets are of significant concern in rising mains, as concentrations of hydrogen sulfide gas within wastewater can be subsequently converted to sulfuric acid by bacteria in the slime layer on the pipe wall. This may cause corrosion and eventual breakdown of the pipe’s wall.
Therefore, a first step in assessing rising main condition should be the identification of gas pocket locations within the pipeline.
Pure Technologies has performed an analysis of rising mains inspected using acoustic based technologies in order to better characterize the frequency and location of gas pockets. Based on the analysis, it was found that 72% of gas pockets were not at known high points or air release valves, therefore, the most precise way to identify gas pockets within a rising main is through the implementation of inline acoustic inspection technologies.
The collection of gas pocket locations alone will not indicate the condition of the pipeline, but instead identifies locations where an increase in corrosion potential is observed. To ascertain the true condition of a pressure pipe, higher resolution electromagnetic technologies are required. These technologies measure pipe wall thickness in ferrous materials and broken wire or bar wraps in concrete pressure pipe.
Once the condition data is collected, advanced analytics can be applied to estimate the pipeline’s remaining useful life.
“Previous analyses involved straight-line assumptions – comparing the pipe wall thickness at installation against what it is today. However this doesn’t give an accurate picture of how pipes degrade…by using statistical modeling we can develop a more predictable degradation rate based off of over 14,000 miles of inspection data Pure has collected over the past 30+ years.”
Jennifer Steffens, Market Sector Leader, Water and Wastewater, Pure TechnologiesWhile often the first thought is to replace the aging wastewater assets based on factors such as age and failure history, this option makes neither logical nor financial sense. With so many miles of buried pipelines and such limited capital budgets, utilities don’t have hundreds of millions to spend on replacing pipelines which still have remaining useful life.
At Pure Technologies, we believe there is a better way. A more feasible approach to ensuring the safe operation of rising mains is to undertake a risk-based approach to manage their operation. A risk-based approach will provide decision intelligence on which assets require rehabilitation or replacement to extend their useful life. Or which assets can be left alone.
Our approach is to help utilities evaluate the current state of their buried infrastructure and provide them with high confidence condition and operating data. We then couple this with our years of extensive experience and project history (more than 12,000 kilometers of pressure pipe assessment) to provide utilities with actionable information, which allows them to make informed decisions as to the management of these critical assets.
Utilities that embrace a risk-based approach to manage their rising main inventory have found that on average they can safely manage their rising mains for roughly 5 to 15 percent of the replacement cost. This pragmatic approach focuses on providing real condition data through assessment, which can be used to selectively renew isolated areas of damaged pipe in lieu of capital replacement.
At Pure, we recommend a risk-based approach to manage wastewater rising mains by focusing on four main areas:
Most common reasons for pipeline failure.
Preliminary analysis includes collecting the right data to develop a prioritized plan for assessment, including the selection of appropriate technologies. To help make preliminary decisions, Pure collects all available information to understand the history of the pipeline and the likely failure modes. The data analysis will provide an understanding of the construction and context of the pipeline. Data of interest typically includes pipe characteristics, installation factors, environmental and performance-related data, operational data, and failure data.
Acoustic-based SmartBall® tool used to locate leaks and gas pockets.
Sahara is an inline tethered tool that can locate leaks and gas pockets.
An internal corrosion potential survey uses inline tools to locate gas pockets that can increase the potential for corrosion and eventual breakdown of the pipe wall. Pure Technologies typically deploys its acoustic-based SmartBall® leak and gas detection tool, as well as its tethered Sahara® leak and gas pocket detection platform to locate gas pockets in pressurized lines of all materials.
While the presence of gas pockets may indicate areas of potential concern, it will not give a quantifiable answer as to the structural life of the pipe.
Pipe wall assessment is completed using a variety of technology solutions to identify defects and deterioration of the pipe wall in a variety of pipe materials. For pipe wall assessment of metallic rising mains, common internal electromagnetic technologies include the PipeWalker® and PureRobotics® platforms, as well as the free-swimming 24-detector PipeDiver® assessment tool, developed to identify electromagnetic anomalies indicating pipe wall loss.
PipeDiver® assessment tool, identifies electromagnetic anomalies indicating pipe wall loss.
Condition data analysis and risk assessment evaluates how to safely renew or extend the life of rising mains. The risk evaluation considers not only the probability of failure (condition) of the rising main based on inspection data, but also the consequence of failure in order to make sound engineering decisions.
Understanding the risk of the pipeline is an important step in selecting and justifying the appropriate condition assessment methods. As the risk of the asset increases, the value of using high-resolution comprehensive assessment techniques increases. Higher resolution data results in more confident decision making, and would justify and prioritize the application of assessment techniques.
In the past, inspections were done, the data analysed, and the results passed on to the utility. Pure Technologies now offers a more holistic program of diagnostic analytics. This includes analysis of what caused the corrosion problem within the pipe wall, what the impact the corrosion has on the life of the pipeline, and a prescriptive analysis of how it needs to be repaired or rehabilitated.
The next step gathering momentum? Predictive analysis to elongate service life.
After the Clean Water Act of the 70s required control of wastewater discharge, an increase in force main construction and management across the country was observed. As these assets are now approaching 50 years in age, reducing the risk of failure has become a major regulatory priority. Nothing grabs headline news like the failure of a force main, which can be extremely damaging to the environment and harmful to a utility’s reputation.
Historically, wastewater force mains have been difficult to manage, especially those made with ferrous materials, where the failure method is slow when compared to concrete pressure pipe.
As well, pressurized sewer mains have special operational challenges that don’t apply to gravity sewer mains as they typically cannot be taken out of service for inspection, and due to the presence of solids in the fluid, force mains represent a far more abrasive environment than potable systems such that assessment methods for water mains may not be applicable.
The presence of gas pockets increases the potential of corrosion in metallic pipes.
The primary failure mechanism of ferrous force mains is due to internal corrosion. Gas pockets are of significant concern in force mains, as concentrations of hydrogen sulfide gas within wastewater can be subsequently converted to sulfuric acid by bacteria in the slime layer on the pipe wall. This may cause corrosion and eventual breakdown of the pipe’s wall.
Therefore, a first step in assessing force main condition should be the identification of gas pocket locations within the pipeline.
Pure Technologies has performed an analysis of force mains inspected using acoustic based technologies in order to better characterize the frequency and location of gas pockets. Based on the analysis, it was found that 72% of gas pockets were not at known high points or air release valves, therefore, the most precise way to identify gas pockets within a force main is through the implementation of inline acoustic inspection technologies.
The collection of gas pocket locations alone will not indicate the condition of the pipeline, but instead identifies locations where an increase in corrosion potential is observed. To ascertain the true condition of a pressure pipe, higher resolution electromagnetic technologies are required. These technologies measure pipe wall thickness in ferrous materials and broken wire or bar wraps in concrete pressure pipe.
Once the condition data is collected, advanced analytics can be applied to estimate the pipeline’s remaining useful life.
“Previous analyses involved straight-line assumptions – comparing the pipe wall thickness at installation against what it is today. However this doesn’t give an accurate picture of how pipes degrade…by using statistical modeling we can develop a more predictable degradation rate based off of over 14,000 miles of inspection data Pure has collected over the past 30+ years.”
While often the first thought is to replace the aging wastewater assets based on factors such as age and failure history, this option makes neither logical nor financial sense. With so many miles of buried pipelines and such limited capital budgets, utilities don’t have hundreds of millions to spend on replacing pipelines which still have remaining useful life.
At Pure Technologies, we believe there is a better way. A more feasible approach to ensuring the safe operation of force mains is to undertake a risk-based approach to manage their operation. A risk-based approach will provide decision intelligence on which assets require rehabilitation or replacement to extend their useful life. Or which assets can be left alone.
Our approach is to help utilities evaluate the current state of their buried infrastructure and provide them with high confidence condition and operating data. We then couple this with our years of extensive experience and project history (more than 12,000 kilometers of pressure pipe assessment) to provide utilities with actionable information, which allows them to make informed decisions as to the management of these critical assets.
Utilities that embrace a risk-based approach to manage their force main inventory have found that on average they can safely manage their force mains for roughly 5 to 15 percent of the replacement cost. This pragmatic approach focuses on providing real condition data through assessment, which can be used to selectively renew isolated areas of damaged pipe in lieu of capital replacement.
At Pure, we recommend a risk-based approach to manage wastewater force mains by focusing on four main areas:
Some of the common reasons leading to failure on ferrous pipes.
Preliminary analysis includes collecting the right data to develop a prioritized plan for assessment, including the selection of appropriate technologies. To help make preliminary decisions, Pure collects all available information to understand the history of the pipeline and the likely failure modes.
The data analysis will provide an understanding of the construction and context of the pipeline. Data of interest typically includes pipe characteristics, installation factors, environmental and performance-related data, operational data, and failure data.
Acoustic-based SmartBall® tool locates leaks and gas pockets.
Sahara is an inline tethered tool used to locate leaks and gas pockets in pressurized lines.
An internal corrosion potential survey uses inline tools to locate gas pockets that can increase the potential for corrosion and eventual breakdown of the pipe wall. Pure Technologies typically deploys its acoustic-based SmartBall® leak and gas detection tool, as well as its tethered Sahara® leak and gas pocket detection platform to locate gas pockets in pressurized lines of all materials.
While the presence of gas pockets may indicate areas of potential concern, it will not give a quantifiable answer as to the structural life of the pipe.
Pipe wall assessment is completed using a variety of technology solutions to identify defects and deterioration of the pipe wall in a variety of pipe materials. For pipe wall assessment of metallic force mains, common internal electromagnetic technologies include the PipeWalker® and PureRobotics® platforms, as well as the free-swimming 24-detector PipeDiver® assessment tool, developed to identify electromagnetic anomalies indicating pipe wall loss.
PipeDiver® assessment tool identifies electromagnetic anomalies indicating pipe wall loss.
Condition data analysis and risk assessment evaluates how to safely renew or extend the life of force mains. The risk evaluation considers not only the probability of failure (condition) of the force main based on inspection data, but also the consequence of failure in order to make sound engineering decisions.
Understanding the risk of the pipeline is an important step in selecting and justifying the appropriate condition assessment methods. As the risk of the asset increases, the value of using high-resolution comprehensive assessment techniques increases. Higher resolution data results in more confident decision making, and would justify and prioritize the application of assessment techniques.
In the past, inspections were done, the data analysed, and the results passed on to the utility. Pure Technologies now offers a more holistic program of diagnostic analytics. This includes analysis of what caused the corrosion problem within the pipe wall, what the impact the corrosion has on the life of the pipeline, and a prescriptive analysis of how it needs to be repaired or rehabilitated.
The next step gathering momentum? Predictive analysis to elongate service life.
In North America, the material and size of pipes that make up water and sewer networks range widely. Because these pipeline systems are so complex, it requires a strategic approach based on risk and real data for effective long-term management.
Historically, however, it has been challenging to gather real data that can shape defensive capital decisions for an entire system. The assessment of metallic pipelines — which make up most water and pressurized sewer networks — differs from prestressed concrete cylinder pipes (PCCP), both in terms of failure modes and in the fact that metallic pipe materials are featured in both transmission and distribution networks.
While PCCP assessment and management have been successfully used by utilities for years, effective assessment solutions for ferrous pipe have only recently been commercialized.
In 2011, Pure Technologies began an initiative to help close the gap in metallic pipe assessment technologies, and focus attention on gathering honest feedback from proactive utilities on what solutions are needed to effectively manage metallic pipe.
Seven years later, Pure Technologies reports that notable progress has been made with the development and advancement of assessment technologies for metallic pipeline networks.
Proactive utilities have been involved in the metallic pipe initiative, and instrumental in the development of new inspection tools for metallic pipe, both by providing feedback that helps guide research and development, and by providing opportunities that allow solution testing in live operating conditions. As a result of these efforts, there has been significant improvements to the technologies available to utilities for assessing the condition of metallic pipelines in both transmission and distribution networks.
For large-diameter transmission mains, there is a well-developed business case for assessing these mains as they approach the end of their useful life. These pipelines typically carry a high replacement cost and are higher risk — due primarily to their size and criticality — making it important for utilities to fully understand the condition of the asset.
Armed with real condition data, utilities can make a defensible renewal or replacement decision about the pipeline. Based on well over 14,000 miles of data, Pure Technologies has found that only a small percentage of pipes are in need of immediate renewal.
In distribution networks, however, the case for condition assessment is more challenging as smaller pipelines can sometimes be replaced cost-effectively. Despite this, the process for making a replacement decision should be based, whenever possible, on risk and real data.
With the EPA suggesting that between 70 and 90 percent of pipes being replaced have remaining useful life, the case is even stronger for collecting condition data to drive the decision making to help utilities spend their replacement dollars more efficiently and avoid replacing pipe with remaining useful life.
In some instances with smaller diameter pipes, it is often cost-efficient to use inline tools to gather detailed screening data on a pipe-by-pipe basis to determine if replacement is necessary.
While there is no silver bullet technology for assessing metallic pipelines, Pure has developed a flexible, risk-based approach to help utilities better understand their infrastructure, gather actionable data and prioritize both short and long-term management efforts.
Over the past few years, Pure has worked along proactive utilities to develop its data-driven Assess and Address® approach, which focuses on four main areas:
Through the implementation of programs across North America, Pure has found that the majority of pipelines 16 inches and above can be cost-effectively managed for between 5 and 15 percent of the replacement cost.
The first step of any pipeline management program is understanding the system-wide risk along with the benefits and limitations of assessment solutions. This allows for the development of a defensible management strategy that can be implemented to maintain and extend the life of the assets.
Many technologies now exist to provide a snapshot of a pipeline condition at various levels of confidence. It is therefore prudent for utilities to approach technology selection and subsequent analysis based on the risk of each pipeline.
A more thorough risk assessment involves estimating the Consequence of Failure (CoF) and the Likelihood of Failure (Lof) of each pipeline based on internal knowledge, operational history and pipeline characteristics. This initial risk assessment determines which areas of the system require further assessment to acquire real condition data and provides the utility with the necessary information to make an informed technology selection.
By using risk to guide management strategies, owners can ensure they are implementing the right approach, at the right time, with the lowest financial impact. The goal of a management program should always be o focus resources on managing the asset while safely getting the most service life out of the pipeline.
Reducing CoF comes down to improving emergency events through field operations efficiency. Studies have shown that the time to shut down a pipeline had more impact on the consequence of failure than the diameter of the pipeline.
Utilities can reduce CoF — and in turn risk — by gaining a better control on their system, which can be achieved two ways:
For example, if a pipe fails and utility operations staff are unable to locate valves — or the valves are inoperable when they are located — it will take longer to isolate a pipe failure. This will result in greater damage, more water loss and longer outages and repair times as a result of the failure. Implementing a proactive program for control assets that focus on providing better data for field staff reduces CoF by decreasing emergency response time.
Many factors influence the likelihood that a pipeline will fail. Metallic pipelines, specifically, have a variety of failure modes and require a wide array of technologies to accurately assess their condition. Until recently, technologies for metallic pipe assessment have been unavailable or limited in their viability.
As a result, lower risk metallic mains have historically been prioritized for replacement using age, material and break history, while higher risk mains have sometimes been assessed with test pits along the length of the pipeline. After test pitting, statistical methods are used to extrapolate the condition of the test pit locations along the entire pipe length.
Through the development of metallic assessment solutions, condition data shows that pipe distress is often random and localized, meaning that an area of distress identified during the test pit method may inaccurately identify the entire pipeline as distressed, conversely, identify the entire length of pipeline as in good condition.
The development of reliable inline condition assessment tools provides owners with pipe-by-pipe data that gives a more complete picture of the actual condition of the pipeline. This allows for a more targeted management of small sections of pipe instead of generalizing the condition of an entire pipe length. It also allows for the collection of real data to drive pipeline renewal, which allows for more defensible capital decision making.
For utilities with large-diameter networks, waiting for failures to occur before repairing or replacing highly critical mains is not an option.
With a large amount of buried water infrastructure reaching the end of its service life, operators have every incentive to take a proactive approach to asset management.
Nowhere is this more critical than in busy urban centres. The fallout from an unexpected failure can have major societal costs, and greatly diminish public confidence in the utility.
Successful asset management begins with condition assessment, the point at which problems and challenges are understood and shaped into definitive plans from both an operational and financial perspective.
To proactively address their pipeline conditions, operators today have access to variety of tools, technologies and engineering analysis that allow for a comprehensive condition assessment of large-diameter pressure pipes, for both water and wastewater systems.
“Unfortunately there is no ‘silver bullet’ with regard to condition assessment technologies,” said Mike Wrigglesworth, Senior Vice President of Pure Technologies. “Each pipeline is unique, and no single technology is the fix for all situations. A combination of factors, from pipe material to soil conditions, operational challenges, age, installation and third party factors will all play a role in the likelihood of failure. Combined with the consequence of failure, a risk-based approach can then be used to select the best condition assessment tool or technologies.”
While operators can now deploy a number of data-based tools and techniques to assess pipeline conditions, each technology also comes with varying degrees of limitation. For instance, while magnetic flux leakage (MFL) tools provide the highest resolution data for steel pipe, MFL is of limited value for concrete pipe.
Medium resolution techniques such as electromagnetics can identify localized areas of wall loss on metallic pipes such as ductile iron and steel, but not on cast iron pipe as cylinder thickness is often too thick and material properties vary considerably, negatively affecting results. In both cases, it is often prudent to deploy leak detection technologies, as studies show joint defects lead to leaks, and leaks are precursors to failure.
“Often the best solution is to use different but complementary technologies to collect robust condition data that is then evaluated using engineering analysis against a comprehensive risk of failure versus a consequence of failure analysis.”
Sahara® Leak and Gas Pocket Detection
Pure’s proprietary Sahara® inspection platform is a tethered, multi-sensor tool that can identify acoustic-based leaks, gas pockets and visual anomalies in real time, with no disruption to service.
The Sahara tool features a small parachute that uses the product flow to draw the sensor through the pipeline while being controlled from the surface.
SmartBall® Leak and Gas Pocket Detection
SmartBall® is a multi-sensor tool used to identify a variety of conditions in pressurized pipelines. The tool is easy to deploy through existing pipeline features, and travels untethered with the product flow, collecting information.
The tool’s highly sensitive acoustic sensor can locate small leaks and gas pockets, with typical location accuracy within 6 feet (1.8 m).
PipeDiver® Condition Assessment
PipeDiver® is a free-swimming condition assessment tool that operates while the pipeline remains in service.
Originally designed for use in PCCP, the tool has electromagnetic sensors to identify and locate broken prestressing wire wraps. For metallic pipelines, the optimized PipeDiver has the ability to pinpoint localized areas of wall loss.
The tool is also able to deliver video images from inside the pipe.
PipeWalker™ Condition Assessment
The PipeWalker tool provides a viable option for pipeline condition assessment in situations where the pipe is dewatered or where the option to dewater is available.
The tool is equipped with electromagnetic sensors for detecting wire wrap breaks on PCCP pipes and for detecting corrosion on metallic pipes.
PureRobotics® Pipeline Inspection
PureRobotics® is a depth-rated robotic pipeline inspection system that can be configured to inspect pipe applications 24-inches and larger.
Tethered by a high-strength fiber optic cable, the crawler is capable of performing multi-sensor inspections in dewatered pipes or while submerged in depressurized pipes.
The crawler features HD digital CCTV, and can be equipped with electromagnetic sensors, Inertial Mapping, 3-D LIDAR, LASER, SONAR and other tools upon request.
While there are a variety of approaches available for assessing a pipeline’s condition, much of an operator’s effort must go into matching the level of resolution of the approach to the overall risk of the line.
The idea is to put the highest resolution technologies on the most critical lines. In the end, the goal of deploying a particular technology (or complementary technologies) is to identify and locate the areas that need rehabilitation or repair as opposed to wholesale replacement of those lines.
Armed with the right information, operators can determine remaining useful life, and confidently move forward to prioritize and target capital spending, while avoiding failures.
Case Study
K-water, the national bulk water utility in South Korea, supplies water across the country to smaller cities and controls everything from collection, treatment and pumping to maintenance, inspection and rehabilitation of the nation-wide pipeline system.
In addition to supplying treated water to these small cities, many have contracted K-water to manage and maintain their distribution systems as they battle the challenges of aging infrastructure. Beginning in 2011, K-water has used Sahara® Leak Detection to address non-revenue water and collect condition information about its metallic pipelines.
Services |
Sahara® Leak Detection NRW reduction program Baseline condition assessment |
Timing |
2012-ongoing |
Pipe Material |
Steel, Cast Iron, Ductile Iron |
Diameter |
6-inch (150mm) to 90-inch (2300mm) |
Transmission Type |
Water |
In 2009, K-water was searching for a large-diameter leak detection tool for its critical trunk mains. While K-water has done an exemplary job of maintaining its nation-wide pipeline network, which totals about 5,000 kilometers and has a Non-Revenue Water (NRW) rate of about 2 percent, many of its client municipalities suffer from high levels of NRW as their infrastructure ages and begins to leak. K-water was also interested in a tool that would allow them to compare actual pipeline conditions with their extensive pipeline engineering knowledge, allowing for quality condition assessment and failure prevention. In 2011, K-water began a knowledge-transfer program with Pure Technologies to become independent operators of Sahara leak detection.
K-water has built up expert knowledge in pipeline engineering, a database of information on their pipe materials and pipe failure methods, and has adopted the best condition assessment technologies in the market to help inspect their pipelines so that efficient, prioritized rehabilitation and replacement plans can be made.
One condition assessment tool K-water has adopted is the Sahara platform – a tethered system with acoustic leak detection and inline video. While many utilities around the world use this tool for large-diameter leak detection, K-water has adopted it in an innovative way, choosing to use it as a complete condition assessment tool to provide information on its pipelines and accurate location of leaks.
The tool is non-destructive and is pulled by the flow of water by a small drag chute. When the sensor is inserted into a tap, it remains tethered to the surface to allow for immediate checking of suspected leaks and gas pockets, internal pipe wall conditions and pipeline features by winching the sensor back and forth from the surface. The sensor is also tracked at ground level by a staff member, allowing for precise spot markings for excavations. Sahara also provides real-time inline video, which allows the operator to see live pipe conditions as the tool surveys for leaks and gas pockets.
Operating with a national mandate and several stakeholders, K-water faces a number of logistical challenges with its pipeline infrastructure.
One challenge is population density; South Korea is roughly 2 per cent of the size of Canada with almost double the population, meaning large, densely populated regions rely on K-water for consistent water service. A failure or service interruption to a critical trunk main could be disastrous K-water’s credibility with customers.
South Korea is also a very mountainous region, meaning pipelines supplying water throughout the country often pass through areas that are difficult to inspect using traditional methods. In addition to the landscape, many of K-water’s large diameter pipelines are buried deep in the ground, making excavation projects complex and expensive to complete.
By becoming certified Sahara tool operators, K-water staff can deploy the tool at their own descretion and are able to overcome these challenges to complete inspections in difficult regions.
Tongyeong City, South Korea, which has a high NRW and features 32-inch (800-mm) steel pipe, has been inspected twice; first as part of Pure’s Sahara training program and subsequently by K-water as an independent operator. The inspections in Tongyeong City were extremely successful, locating 10 total leaks with high accuracy in 2.5 kilometers of inspection for an estimated savings of 350,400 cubic meters of water per year.
During the training inspections, Pure and K-water were able to locate pinhole leaks as close as 5-cm above and below the actual leak location – meaning service disruption, excavation and repair times were minimal. In K-water’s subsequent inspection of the same pipeline in Tongyeong City, they were able to excavate and repair all three identified leaks in 5.5 hours each during the night (3 separate repairs), causing little disruption to customers.
In total, K-water has inspected 25 kilometers of pipeline and located 22 leaks of varying sizes. K-water has inspected both its own pipelines as well the regional pipelines that it operates and has covered pipes with diameters as small as 150-mm and as large as 2300-mm, with most pipe being either steel, ductile iron or cast iron pipe. K-water’s 2012 program will cover about 52 kilometers of pipeline for leaks and gas pockets
While the tool has been effective in locating leaks for K-water, its value as a complete condition assessment tool has also been helpful due to the unique challenges faced in South Korea. K-water has been able assess the state of its pipelines by combining the inline video data and its extensive engineering knowledge. By doing this, K-water has become a thought-leader in large-diameter pipeline management.
K-water has successfully applied the Sahara platform for condition assessment in its transmission mains and for leak detection in municipal trunk mains.
Se-Hwan KimCase Study
The City of Montreal supplies drinking water and wastewater services to a population of nearly 1.9 million people. Starting in 2007, Pure Technologies (Pure) began working with the City’s potable water transmission division on a pipeline assessment program that included electromagnetic (PureEM) inspection and acoustic monitoring.
In 2015, as part of a pre-emptive program to reduce loss of non-revenue water and understand the condition of their pipes, the City partnered with Pure to conduct an ongoing, three-year leak detection survey on a series of critical pipes within its potable water network located mostly in the downtown core.
Services |
Sahara® leak detection
CCTV visual inspection |
Timing |
2015-Ongoing |
Pipe Material |
BWP, Steel, Cast Iron, PCCP |
Inspection Length |
28.9 km (18.5 m) |
Diameter |
500mm – 1200mm (20-inch – 48-inch) |
Transmission Type |
Water |
In addition to physical losses of water caused by a series of small leaks, the escaping water can eventually erode the surrounding soil making the area more prone to washouts or sinkholes, a major headache especially in densely populated areas. Leaking water can eventually find its way to the surface, or into sewers, overburdening the system. Unplanned excavations to repair unforeseen leaks can also erode consumer confidence in a public utility.
The Sahara platform comes with a variety of sensor tools to perform the inspection. This includes an acoustic sensor to perform leak and gas pocket detection, and high-resolution video camera to assess internal pipe conditions.
Because the Sahara tool is drawn by product flow via a small drag chute, and is tethered to a data acquisition unit on the surface, it gives the operator close control to confirm suspected leaks, gas pockets and other visual anomalies. The tool can visually confirm pipe irregularities, continuously recording, allowing for both real-time and post-processing analysis.
For the Montreal project, the purpose of the Sahara inspection was to assess the condition of the pipeline by identifying and locating leaks, pockets of trapped gas and to identify larger visual anomalies utilizing Closed Circuit Television (CCTV) footage collected during the inspection. The data would help shape the rehabilitation urgency and timing.
The assessment is proving its worth from a verification viewpoint, and the leaks have been either repaired or addressed for prioritization. The current program is scheduled for completion by 2017.
With its pre-emptive leak detection program, the City is Montreal is a great example of a smart water manager taking proactive efforts at keeping its network in healthy shape.
Since 2007, utilities all over the world have been using the SmartBall® pipeline inspection platform to save millions of dollars in water loss and to fix leaks before they turn into larger problems.
Developed by Pure Technologies (Pure), the tool is trusted by utilities for two main reasons. One is for condition assessment purposes, and the other is for reducing non-revenue water. From a condition assessment perspective, SmartBall® is a proactive tool that can be used as part of a larger holistic approach to help identify problem areas that require repairs before they turn into bigger issues, and also to help utilities prioritize capital spending.
The primary purpose of the SmartBall tool is to detect and locate the acoustic sounds related to leaks and gas pockets.
“Unlike traditional correlators, the SmartBall sensors travel inline along the pipe, inspecting every inch of the water main to detect potential problems such as leaks and gas pockets. Based on thousands of miles of experience, the SmartBall tool has found three to four times more leaks than trunk main correlators, which are traditionally used in smaller diameter pipes, and are less effective for transmission mains and larger diameter pipes.”
Cam WhiteWhat makes the SmartBall tool so remarkable is its ability to get into and out of pipelines very easily, and to be deployed for long runs in one inspection for both water and wastewater pipelines. The tool requires only two access points – one for insertion and one for extraction.
For insertion, the foam-shelled SmartBall tool is placed into a claw, compressed, and then lowered into the line through a 4-inch (100mm) or larger tap, all while the line is pressurized. Throughout the survey, Pure’s inspection team constantly monitors the SmartBall’s position as it traverses the pipeline collecting data.
There are many alternative options available to get the SmartBall in and out of a pipeline. Having multiple options reduces the money and effort required by utilities to support the inspection.
Once the inspection is complete, the data is extracted from the ball and sent to Pure’s data analysts where they will identify leaks and gas pockets.
As utility owners know, it can be expensive to excavate, and what SmartBall tool does is provide information that’s accurate, so clients can dig up the pipeline and find the leak the first time.
The “leak-where-predicted” scenario recently happened with the City of Ottawa when Pure deployed its SmartBall inspection platform to locate leaks and pockets of trapped gas along a critical transmission main, as part of a long-term condition assessment program for the municipality.
The Baseline Road Water Transmission Main is a high priority 1220mm (48-inch) diameter pipeline comprised of lined cylinder pipe (LCP).
For the City of Ottawa project, five (5) surface-mounted acoustic sensors were placed along the pipeline to track the SmartBall tool during the inspection. The SmartBall device was inserted into the pipeline through a 100mm drain near a hospital. Acoustic and sensor data was collected and recorded as the SmartBall tool traversed the pipeline for more than three kilometers.
From the survey results, Pure detected one (1) acoustic anomaly characteristic of a leak and zero (0) anomalies consistent with pockets of trapped gas.
The “leak-where-predicted” scenario recently happened with the City of Ottawa when Pure deployed its SmartBall inspection platform to locate leaks and pockets of trapped gas along a critical transmission main, as part of a long-term condition assessment program for the municipality.
The Baseline Road Water Transmission Main is a high priority 1220mm (48-inch) diameter pipeline comprised of lined cylinder pipe (LCP).
For the City of Ottawa project, five (5) surface-mounted acoustic sensors were placed along the pipeline to track the SmartBall tool during the inspection. The SmartBall device was inserted into the pipeline through a 100mm drain near a hospital. Acoustic and sensor data was collected and recorded as the SmartBall tool traversed the pipeline for more than three kilometers.
From the survey results, Pure detected one (1) acoustic anomaly characteristic of a leak and zero (0) anomalies consistent with pockets of trapped gas.
Although Pure was confident in the SmartBall leak detection data, sometimes it’s worth a try to verify an anomaly with a complimentary technology. In this instance, ground microphones, regarded as a conventional a leak detection tool, were deployed to try and detect leak sounds. Although the suspect area was marked, neither Pure nor the client could pick up leak-related sounds from the ground microphone.
Even though the leak was not picked up by the ground microphone, Pure was confident that the acoustic signature from the SmartBall was caused by a leak, based on more than 15 years of experience identifying leaks. That confidence and experience proved right, and when the suspected area was excavated, the leak was located within a meter of where the data analyst calculated the leak to be.
The results gave the City of Ottawa actionable data regarding the condition of their pipeline, and the City was able to fix the leak reducing non-revenue water loss and any potentially costly damage caused by the leak. It’s a great example of a proactive utility taking efforts to improve the reliability of its services.
With a population of nearly 500,000, Lyon is the third largest city in France, a vibrant metropolis known for its modern Confluence district as well as Renaissance palaces and Roman ruins that date back more than 2,000 years.
While Lyon’s historic architecture has aged well, the same cannot be said for its buried infrastructure. In June of 2016, Suez retained the services of Pure Technologies (Pure) to perform a SmartBall® inspection of two critical water mains, the Grigny Water Main and Les Halles Water Main, both located near Lyon. The inspections, conducted over two days, were part of a long-term condition assessment program for the city.
As an industrial services and solutions company specialising in securing and recovering resources, Suez provides its customers (local authorities, industry and consumers) with concrete solutions to address new resource management challenges.
The Grigny Water Main is a 500mm (20-inch) cast iron pipeline that transfers Water from the Grigny Pump Station to Saint Romain en Gier. The SmartBall inspection started at a previously installed 150mm (6-inch) tap and ended at a previously installed 150mm tap in Saint Romain en Gier, and covered a distance of approximately 8.6 kilometers (5.3 miles).
The following day Pure deployed a second SmartBall inspection, this time on the Les Halles Water Main, a 400mm (16-inch) ductile iron pipeline that transfers water from Les Halles to Saint Laurent D Chamousset. The purpose of the inspection was to locate and identify leaks and pockets of trapped gas along the 2.9 kilometer (1.8 mile) section of pipeline.
The SmartBall tool was chosen as an inspection platform for its sensitivity to small leaks, minimal pipeline modifications required for insertion and extraction and its ability to inspect long distances in a single deployment. The free-swimming, acoustic-based SmartBall tool is inserted into the pipeline flow, and after traversing the inspection length, the tool is captured and extracted at a point downstream.
During inspection, the SmartBall tool’s location is tracked at known points along the alignment to correlate the inspection data with specific locations. As the SmartBall tool approaches a leak, the acoustic signal will increase and crescendo at the point when the tool passes the leak.
For this project, 13 surface-mounted acoustic sensors (SMS) were placed along the Grigny pipeline to track the SmartBall tool during the inspection. For the Les Halles inspection, five (5) SMS were used to track the tool. SmartBall receivers were connected to the sensors on the pipeline at locations to track the tool during inspection.
An extraction net was used to extract the SmartBall tool once it traversed the entire length of both pipelines, and the data was evaluated by Pure analysts to identify acoustic anomalies associated with leaks and pockets of trapped gas.
The acoustic data recorded by the SmartBall tool was analyzed and cross-referenced with the position data from each SmartBall Receiver (SBR) to determine a location for each acoustic anomaly.
From the results conducted on the Grigny Water Main, Pure detected a total of two (2) acoustic anomalies characteristic of leaks and zero (0) anomalies consistent with pockets of trapped gas. Pure analysts classified one leak as a small leak, and a second as a large leak.
For the survey of the Les Halles Water Main, Pure detected zero (0) anomalies characteristic of leaks and zero (0) acoustic anomalies characteristic of pockets of trapped gas.
The results gave Suez actionable data regarding the condition of the pipelines, and the confidence to move forward on fixing the leaks. It’s a great example of a water authority taking proactive efforts at keeping its network in healthy shape.
What keeps a water utility manager up at night? Getting a phone call from a distraught resident about an unplanned (and unwanted!) ornamental pond developing in the cul-de-sac.
On an already soggy, wet day in early November 2016, water began filling a cul-de-sac in an affluent neighbourhood in the City of Southlake, Texas. To contain surface flooding, Southlake water authorities took immediate remedial action by sequentially shutting down each water line in the area in an attempt to isolate the leak.
In addition, the City used external listening devices to try and locate the leak – the external listening devices indicated that some kind of leak was present, but the City was unable to pinpoint the location. In the end, the City had to shut down the 42-inch Caylor bar-wrapped potable water main, a low-pressure gravity main passing through the area. This was done to confirm that the 42-inch Caylor Main was leaking.
Sure enough, once the 42-inch Caylor Main was shut down, the water stopped surfacing. When the City reopened the main, the water did not resume surfacing. Despite the inconclusive evidence, the City remained convinced that the 42-inch main was the leak source.
With uncertainty remaining, the City of Southlake called in Pure Technologies to assist in identifying and locating the leak. Unfortunately, the bad luck continued, as heavy rains and muddy conditions hampered Pure and its mobilization truck from access to the pipeline right-of-way. Even crews from Southlake got stuck when they tried drive the pipeline right-of-way.
One possible additional access point was available through a private owner’s horse pasture, but low-hanging power lines created a safety hazard that would prevent crews from accessing the site by that route.
Disappointed, the crews demobilized to wait for better weather or a better access point.
The next day Southlake identified another access point 1,000 feet further upstream, and prepared it for the Sahara inspection.
The Sahara leak detection platform was selected for its ability to provide same day results, and to accurately locate small leaks with sub-meter accuracy. The tethered tool is propelled by a small parachute inflated by the product flow, requiring a flow velocity as little as one foot per second to progress through a water main.
Because the Sahara inline tool is tethered, an operator has complete control, and can closely examine events of interest such as leaks, gas pockets and visual anomalies in real time.
For the assembled crews, pressure escalated to quickly find the leak location.
Once the Pure mobilization crew set up the installation equipment and inserted the Sahara sensor, the pressure gauge indicated only 36 PSI, not the best scenario for leak detection. Furthermore, the inspection was heading uphill toward the area of interest, and could expect even lower pressure nearer to the suspected leak location area due to loss of head pressure as the pipe ascended the slope.
Further complicating matters, the pipe wall thickness was determined to be about 4 inches, and leak paths that pass through 4 inches of concrete and mortar can often include sharp bends that can muffle leak signatures.
From the insertion point, Sahara inspected a total of 2,400 feet, passing through the cul-de-sac area at around 1,600 feet from insertion.
During deployment, review of acoustic data noted a few areas of interest, but nothing definitive. The inspection continued past these areas of interest in the hopes of finding something more conclusive. When nothing was found, the Pure crew began a slow pullback of the tethered Sahara tool to recheck the areas of interest.
One of the benefits of a tethered tool is that two inspection passes can be conducted on the same section on the same day.
Of the possible leak areas, one acoustic anomaly seemed promising, and that spot was marked above ground.
Because this suspected leak did not, even in post analysis, present with all the elements of a leak signature, and because it lacked a distinctive peak location, Pure Technologies recommended that the City of Southlake check a 7-foot length of the pipe, all the way around the pipe.
As directed, Southlake crews excavated the indicated areas and found not one but four leaks. The presence of four leaks in close proximity to one another, all at low pressure, explained the difficulty of finding a leak peak.
The four leaks located ranged from pencil-sized to quarter-sized. The sloppy mortar job over an access plate into the 42-inch Caylor Main was just good enough to help muffle the leaks, but not good enough to protect the cylinder from corrosion and eventual leakage.
In the end, despite difficulties of inspecting small leaks in a low-pressure environment, the inspection was deemed a success, and Southlake was extremely pleased with the accurate results.
Thanks to collaboration between crews from Southlake and Pure, the mystery leak was solved. The inline tethered Sahara tool came through again.
Rand Water is the largest bulk water utility in Africa and one of the largest in the world, providing bulk potable water to more than 23 million people in Gauteng, parts of Mpumalanga, the Free State and North West – an area that stretches over 31,000 square kilometres. Rand Water’s distribution network includes over 3,300 kilometres of large-diameter pipelines.
In 2015 Rand Water embarked on the largest proactive bulk water pipeline condition assessment investigation ever in South Africa. An important part of the assessment includes inline non-disruptive leak detection inspections covering just over 2,200 kilometers of Rand Water’s bulk pipeline network.
The free-swimming SmartBall™ leak detection system is utilized to perform the majority of these inspections. The multi-sensor tool is used to detect and locate the acoustic signature related to leaks and gas pockets in pressurized pipelines. While the SmartBall is deployed, the pipeline remains in service, limiting disruption to customers.
Unlike traditional listening tools like correlators, which have limited success on large diameter pipes, the free-flowing SmartBall technology provides a high degree of accuracy, since as the ball rolls, it can inspect every inch of the main to detect leaks and gas pockets.
Due to the vast transfer distances and varying topography within the supply area, the Rand Water system is characterized by pipelines operating under extreme pressures (higher than 16 bar [232 psi] and up to 40 bar [580 psi]) and high flow velocities (higher than 2 m/s), historically beyond safe operating limits of the standard SmartBall insertion and extraction equipment.
This rendered some of the pipelines unsuitable for inspection unless a solution could be found to safely insert and extract SmartBall from a high pressure/high flow pipeline.
Pure Technologies embraces research and development (R&D), with a strong design focus on continuously developing new inspection technologies and improve existing systems. SSIS Pipeline Services, which represents Pure Technologies in SA, challenged the Pure R&D team to find a solution for this unique high pressure Rand Water problem.
From this challenge, the Titan system was born.
Following extensive R&D and pre-delivery testing, the first-of-its-kind enlarged Titan insertion and extraction system was delivered to South Africa in May 2016. The system included a retrofitted high pressure LDEN (Large Diameter Extraction Net) kit capable for use in pressure environments up to 40 bar (600 PSI) and higher.
SSIS staff underwent shop training at the hands of one of the mechanical design engineers from Pure, followed by hands-on training on a number of high pressure, high velocity Rand Water pipelines.
To date, the Titan system has been used safely and successfully on pipelines up to 2900mm in diameter, operating at 2.5 m/s and at pressures up to 18 bar (261 psi). The system’s highest recorded operating pressure was at 23 bar (333 psi) on a 900mm diameter pipeline with 1.5 m/s flow.
The Titan system now enables SSIS to safely perform SmartBall leak and gas pocket inspections on high pressure pipelines previously off limits.
The latest successful test illustrates the SSIS commitment to the local water industry through innovation and dedicated support from Pure Technologies. It again proves that no problem is too big to solve, and every challenge can be overcome through dedicated teamwork and cutting-edge innovation.
According to AWWA’s 2016 Benchmarking Survey, the average water and wastewater utility has seven breaks per 100 miles of piping every year. Tip-top systems experience just four breaks in that distance, while those at the bottom have 18.
While it’s interesting to note the difference in break rates, it’s unfair to compare one utility to another, as a multitude of factors come into play as to why pipelines can deteriorate to state of failure. Countless sources of stress both inside and outside a pipe related to geographical location, soil-pipe type interactions, age, and construction are among factors that can take their toll on the pipe’s condition.
For utilities, the one constant across the spectrum is the acknowledgment that simply replacing pipeline assets is cost prohibitive, and that advanced condition assessment services like those provided by Pure Technologies (Pure) can help utilities confidently make informed decisions that significantly reduce capital and operating costs.
While single-episode blowouts are quite rare, these tend to garner most media attention, and cause the most obvious blowbacks to the pipeline operator. What the public doesn’t usually notice are the pinhole leaks, hairline cracks, corrosion and leaking gaskets that tend to occur first.
Most catastrophic failures are caused by a sudden unexpected stress such as a water hammer acting on an existing weak point in the pipe. There is a widely held belief that the failure process is a simple one, where a pipe corrodes to the point at which it can no longer withstand the applied internal and external forces, resulting in a main break. However, research has shown that the failure process is more complex than expected.
Corrosion plays a significant role in water main failures, but soil-pipe interactions, manufacturing techniques and human error are also important factors. Failures also take place in multiple stages rather than in a single episode. Early damage not only weakens portions of the pipe, it also allows water to escape, causing corrosion and washing out of the supporting soil.
Pipes at highest risk are typically constructed using dated materials or methods, running through an area with heavy vehicle traffic. Urban centers typically represent significant loss potential from damage caused by water main breaks as a result of high-density buildings, underground infrastructure, important traffic thoroughfares, and economic loss potential of power, gas, water utilities and legal cases.
The net result is that age alone cannot be relied on as an indicator of a high-risk pipe.
Prestressed concrete cylinder pipe (PCCP) has a unique failure mechanism: high strength steel pre-stressing wires that provide strength to the pipe can become distressed and reduce the structural integrity of the pipe. Broken wires can be caused by physical damage to the pipe, corrosion, or hydrogen embrittlement.
Areas of broken wires may be accompanied by leaks, especially in pipelines smaller than 48 inches in diameter, where the internal steel cylinder corrodes at the same rate as the wires or where water escaping through the joint encourages corrosion. Leakage has been proven to be a key indicator of structural condition in lined cylinder pipe, a type of PCCP in which the prestressing wires are placed directly on the steel cylinder. These types of leaks can create voids around the pipe and introduce added stress at an existing weak point.
Cast iron pipes corrode, become brittle and are prone to cracking. Many older North American cities have cast iron pipes that were installed in the 1800s, prior to the existence of pipeline standards, when methods of construction were non-uniform and advanced quality control programs did not exist. Consequently, many pipelines were installed using what are considered poor construction practices by today’s standards.
Ductile iron pipes have failure mechanisms similar to those of cast iron pipes; however they become less brittle and consequently degrade at a slower rate. These pipes may be capable of supporting large leaks for longer periods of time without failing immediately.
Plastic and polyvinyl chloride (PVC) pipes are less prone to corrosion and less brittle than iron pipes. Failures in these pipes are often traced to leaking joints where the escaping water creates voids around the pipeline, causing unplanned stresses on the pipe.
Steel pipes primarily fail due to loss of integrity at welds, and external corrosion causing severe pitting and weakening the pipe wall. Both losses of joint integrity and through-wall corrosion pits lead to leakage long before failure. Older steel pipes in aggressive environments are capable of sustaining massive levels of leakage for decades before failing.
While pipe material and typical pipe stresses are factors that can contribute to a state of pipe failure, it remains impossible to compare one pipeline to another, and to make generalized statements about remaining service life, especially based on age and depreciation. Instead, it pays to conduct ongoing condition assessment, and then to use that risk-driven asset data collection to reduce the likelihood of replacing pipe that can safely and effectively serve communities for several more years.
Justification of an ongoing condition assessment program can, at times, be difficult for water utilities. However, successful inspections that deliver actionable outcomes on how to manage aging assets make this justification much easier.
Certainly that was the case for Mackay Regional Council (MRC) when it engaged the services of Pure Technologies to conduct a variety of condition assessment inspections on their critical mains in order to improve their understanding of these aging assets.
For MRC, the goal of the 3-year Condition Assessment Program is to undertake and then analyze the results from the preliminary inspections, followed by a commitment to explore secondary condition assessments, where warranted.
Mackay Regional Council is a small but progressive water utility that serves a population of nearly 124,000 on the eastern coast of North Queensland, Australia. The utility has a total of 2,150 km of water and wastewater mains in its network. MRC is proactive in its approach to water management, and takes pride in the development of its industry-leading condition assessment program, initiating the first leg of the program with Pure mid-2016.
In June 2016, MRC retained the services of Pure to perform a SmartBall® inspection of the Coles Road Sewer Rising Main (SRM), also known as force main. The Coles Road SRM is an asbestos cement (AC) and ductile iron (DI) pipeline that transfers wastewater from the Coles Road Sewer Pump Station (SPS) to the Mount Basset Sewer Rising Main. The purpose of the SmartBall inspection was to identify leaks and pockets of trapped gas along the pipeline.
Pure recommended the SmartBall tool for its relative ease of insertion and extraction of in-service pipelines, and its ability to inspect long distances in a single deployment. The tool’s acoustic sensor can detect ‘pinhole’ sized leaks and gas pockets within a location accuracy of plus or minus 1.8 m (6 feet), a critical factor in urban environments where excavations can be costly and disruptive to the public.
After the review of data integrity and backup from the Coles Road site, the crew moved to the Beaconsfield SRM, where a further SmartBall inspection was completed. The inspection went as smoothly as the first, and all data was confirmed for quality.
This technology has assisted us in assessing the operational and potential structural integrity of some hard to access buried mains of high failure consequence without significant service outage or worker safety in a way not previously utilised. It certainly lifts us out of the purely reactive mode toward the proactive assessment of buried infrastructure in terms of service delivery risk management and maintenance/renewal planning…”
MRC Project LeaderDuring the next phase of the project, Pure conducted a preliminary condition assessment of two more critical mains, the Mount Basset SRM and the following day, on Marwood Bore Raw Water Main. Pure always utilizes separate inspection sets for potable and wastewater to eliminate any risk of contamination.
Results of the preliminary condition assessment were utilised to identify whether a secondary condition assessment is required.
Historically, it has proven challenging to assess the condition of pressurized mains that carry sewage, especially those made with ferrous material. Sewer rising mains have special operational challenges that don’t apply to gravity sewer systems, and due to the presence of solids in the flow, sewer rising mains represent a far more abrasive environment than potable water systems.
Gas pockets are of significant concern in rising sewer mains, as concentrations of hydrogen sulfide gas within wastewater may be subsequently converted to sulfuric acid by bacteria in the slime layer on the pipe wall. This may cause corrosion and eventual breakdown of the pipe’s exposed surface.
For the third phase of the Program, MRC engaged Pure for a condition assessment of the Gordon Street Water Main. In order to inspect this critical main, Pure conducted three (3) separate insertions using the Sahara inspection platform. The Sahara system uses an innovative tethered platform to conduct non-destructive inline leak and gas pocket detection, and an internal visual inspection via closed circuit television (CCTV), without disruption to service. This allows for real-time reporting of acoustic anomalies detected in the pressurized lines.
The inspection occurred over a period of two nights to minimize traffic disruption. The targeted portion of the main consists of cast iron (CI) and asbestos cement (AC) pipe in three diameters.
“We are still to progress fully into this mode of operation, however this technology appears to provide us a firm foundation to step off from…”
Don Pidsley
All in all, the data collected to date has given MRC a better understanding of their critical assets. By undertaking a preliminary condition assessment approach, MRC now has actionable information regarding the necessity of future secondary assessments.
Based on preliminary results, minimal disruption and collaborative cooperation between the mobilization teams, MRC has inquired about additional inspections under their in their industry-leading condition assessment program.
At Singapore International Water Week 2016, one of Pure`s licencees presented a poster on two acoustic-based technologies (tethered Sahara® and free-swimming SmartBall®) used to locate 674 leaks on large-diameter trunk mains operated by this Malaysia water operator.
Conducted over four months, the in-line inspection and resulting repairs has saved total of 46.7 million liters of water daily. The pipe diameters ranged from 300mm to 2,200mm.
SmartBall in-line leak inspection platform
The SmartBall tool was chosen as an inspection platform for its sensitivity to small leaks, minimal pipeline modifications required for insertion and extraction and ability to inspect long distances in one deployment. The free-swimming, acoustic-based SmartBall assembly is inserted into the flow of a pipeline, traverses the pipeline, and is captured and extracted at a point downstream.
Sahara in-line leak detection platform
The tethered Sahara tool includes an acoustic sensor to perform leak and gas pocket detection, a high-resolution video camera to assess internal pipe conditions, and an electromagnetic sensor to identify stress in the pipe wall. Because the parachute-like tool is drawn by product flow and is tethered to a data acquisition unit on the surface, it gives the operator close control to confirm suspected leaks, gas pockets and other pipeline anomalies.
The City of Montreal believes that the best medicine is preventative medicine, especially as it applies to its water network.
Montreal has an impressive water system that supplies drinking water to a population of nearly 1.9 million people. Since 2002, the historic city, the second largest metropolis in Canada, began a long-term major rehabilitation of its extensive network of water main (770 kilometers) and distribution pipes (4,600 kilometers).
In 2015, as part of a pre-emptive program to reduce loss of non-revenue water, the City partnered with Pure Technologies (Pure) to conduct an ongoing, three-year leak detection survey on a series of critical pipes within its network, several of which are located in the downtown core.
The City recognized the value of detecting leaks, however small, to prevent these from developing into greater problems. Compared to a major pipe rupture, which can cause catastrophic damage and incur immediate excavation and costly repairs, small leaks are less obvious at first, and can seep underground for some time without obvious detection.
In addition to physical losses of water caused by a series of small leaks, the escaping non-revenue water can eventually erode the surrounding soil making the area more prone to washouts or sinkholes, a major headache especially in densely populated areas. Unplanned excavations to repair unforeseen leaks can also erode consumer confidence in a public utility.
For its multi-year leak detection program, the City requested Pure to deploy its highly reliable and precise Sahara® acoustic video inspection on 46 kilometers of pipelines chiefly in the downtown core. The pipeline sections consist of bar wrapped, steel and cast iron pipe.
The Sahara platform is modular, and can be configured with a variety of sensor tools to perform the condition assessment. This includes an acoustic sensor to perform leak and gas pocket detection, a high-resolution video camera to assess internal pipe conditions, and an electromagnetic sensor to identify stress in the pipe wall.
Because the Sahara tool is drawn by product flow via a small drag chute, and is tethered to a data acquisition unit on the surface, it gives the operator close control to confirm suspected leaks, gas pockets and other pipeline anomalies. The tool can visually confirm pipe irregularities, continuously recording, allowing for both real-time and post-processing analysis.
For the Montreal project, the purpose of the Sahara inspection was to assess the condition of the pipeline by identifying and locating leaks, pockets of trapped gas and to identify larger visual anomalies utilizing Closed Circuit Television (CCTV) footage collected during the inspection. The data would help shape the rehabilitation urgency and timing.
The leak detection program has not been without challenges. Valve operations were needed to achieve required pressure flows, and mobilization had to be based on hours of demand, and inspections conducted during those hours. A number of tight chamber clearances meant the creation of new insertions taps, and because of the urban environment, markings had to be precise, and crews had to deal with traffic issues.
Despite challenges, the assessment is proving its worth from a verification viewpoint, and the leaks have been either repaired or addressed for prioritization. The current program is scheduled for completion by 2017.
With its pre-emptive leak detection program, the City is Montreal is a great example of a smart water manager taking proactive efforts at keeping its network in healthy shape.
Traditional methods of wastewater condition assessment focuses almost exclusively on the gravity system and valve
actuation, using tools such as smoke testing, CCTV, and zoom cameras. While effective on gravity mains and valves,
these methods are not applicable in force mains.
Inspecting force mains is more challenging due to lack of redundancy, lack of access points, cost, technology limitations, while the consequence of force main failures can be significant financially, environmentally and socially.
A successful wastewater asset management program uses a holistic approach which prioritizes the entire system, collects data through condition assessment and provides analyzed reports in order to develop a targeted, informed action plan for long-term sustainability of a collection sewer system.
Dallas Water Utilities Discovers Massive Hidden Sinkhole And Achieves Huge Savings Through Annual Leak Detection Program
The year began with the Lone Star state experiencing its fourth year of drought, compelling State Governor Greg Abbott to reissue an Emergency Disaster Proclamation in early May to deal with the declining aquifer levels and severe water shortages. Only a few weeks later, torrential rains flooded so much of the state that the Governor issued another Emergency Disaster Proclamation to prepare for the new crisis. Then, another long stretch of baking heat.
For most utilities, weather can play havoc with buried infrastructure. While drought can cause the dry brittle ground to shift and pipes to break, excessive rain can result in washouts, loss of bedding and risk for accelerated pipe failures.
In 2015, weather extremes in such a short period taxed water utilities across Texas. Despite the challenging environmental conditions, Dallas Water Utilities (DWU) moved forward to carry out its annual leak detection program. Over the years, DWU has focused its water loss reduction efforts on both its critical large-diameter transmission mains, which have the highest consequence of failure, and on its distribution systems.
Detection results include discovery of a large pipe leak near a major roadway
Crews successfully used the Sahara® tool to locate 10 leaks in 16 miles of inspection.
DWU’s first condition assessment program using electromagnetics was completed in 2001, followed by the use of newer leak detection technologies in succeeding years. The program is now in its 14th year of operation, and DWU has become a showcase utility for proactive pipeline management, a fact recognized by the Texas Water Development Board.
DWU’s distribution system is one of the largest in the United States, being a regional provider, the utility delivers water service to 2.4 million customers within the Dallas and surrounding city limits. The major distribution system includes over 4,900 miles (7,800 km) of distribution and transmission mains.
DWU’s goal is to continually evaluate, upgrade and replace its water and wastewater assets in order to make its systems operate efficiently. DWU’s long-time partner in this infrastructure endeavour is Pure Technologies (Pure). This year Pure was contracted to perform leak and air pocket detection for 16 miles (25.7 kilometers) of water mains made of a variety of materials, including prestressed concrete cylinder pipe (PCCP), cast iron pipe (CIP) and ductile iron pipe (DIP).
For inspection of its transmission mains, DWU has long used Sahara leak detection and inline closed circuit video (CCTV) provided by Pure. More recently, DWU has also used SmartBall® technology for longer inspections.
Sahara is the first tool designed for live inspection of large-diameter mains, and one of the most accurate tools available for detecting leaks, gas pockets and structural defects in complex networks typically found in urban environments.
The tool is pulled by the flow of water by a small drag chute while the line remains in service. When the sensor is inserted into a 2-inch tap, it remains tethered to the surface. This allows for real-time results and maximum control, as the tool can be winched back and forth to immediately confirm suspected leaks and other anomalies. The sensor is also tracked at ground level by a staff member, allowing for precise spot markings for excavations.
The 2015 inspections, conducted over 23 days, challenged the Pure and DWU crews as they faced an environment with temperatures soaring to 104°F (41°C) on many consecutive days.
In spite of the trying working conditions, the crews successfully used the Sahara tool to locate 10 leaks in 16 miles of inspection. This included the unexpected discovery of a very large leak in the barrel of a 12-inch ductile iron water main. DWU’s proactive repair prevented a collapse since the large leak was creating a cavernous sinkhole near a major roadway.
By locating and repairing the leak, which had been seeping water for an estimated year, DWU averted a potential catastrophic crisis and saved the utility at least 893,000 gallons of lost water per year, equivalent to filling 1353 Olympic-sized swimming pools.
Large leak discovery saved DWU at least 893,000 gallons of lost water annually, equivalent to filling 1353 Olympic-sized pools.
Sahara and SmartBall inspections in Dallas have been extremely successful, locating 160 leaks in 209 miles. The estimated water savings from these leaks is about 4 MGD. For DWU, the reduction in failures has reduced loss claims and service interruptions, as well as reduced treatment and delivery costs.
Whatever the weather, DWU is moving forward.
A ruptured sewer pipe can attract a lot of unwanted attention, even when it happens on private property. Last year, hours before celebrities were to arrive at the Golden Globes Awards show at the Beverley Hills Hotel, a reputed sewer pipe burst, spewing a mess of wastewater on the red carpet, according to media reports. When large pipes fail, it’s usually breaking news. And when the failed pipeline is part of a pressurized wastewater force main network, repercussions to the environment and the public have the potential to be catastrophic, with fallout to a utility’s reputation. In Canada, pressurized force mains that carry sewage make up only about 7.5 percent of the typical wastewater system compared to gravity mains. Because sewer force mains tend to run constantly, and often operate without redundancy, there is little opportunity to assess the pipes. When problems arise, and a critical force main is out of commission, the entire wastewater system can stop, causing overflows or the need to implement costly bypass pumping. Worse still, pollution generated by a raw sewage leak can flood to the surface and into a watercourse. Clean-up costs can be staggering and environmental impacts can be devastating.
The PureRobotics platform can assess the structural integrity of force mains and provide inline video to observe internal pipe conditions.
Internally, force mains have unique warning signs of failure. Because of the sewage flow, trapped gas pockets can allow concentrations of hydrogen sulfide gas to be released from solution and subsequently convert to sulfuric acid by bacteria on the pipe wall, leading to corrosion of the pipe wall. As the pipe wall corrodes internally, it becomes weaker and more likely to fail unexpectedly. While corrosion and defect failures on sewer pipelines are a fact of life for wastewater utilities, these failures do not occur systemically. As a result, knowing when to replace and when to preserve assets through close inspection is more critical than ever.
Managing force mains proactively can help utilities prevent environmental regulation violations that are expensive to mitigate.
Aging pipes, increasing costs of failures and high replacement costs represent significant challenges facing force main owners. As a result, utilities have come to rely on Pure Technologies for its suite of technologies that can identify the weak links. Selective rehabilitation of force mains maximizes the life of the asset, typically at 10-15 percent of replacement costs. Pure’s strategy employs a risk-management approach that looks at likelihood of failure (LOF) and consequence of failure (COF). LOF variables are related to the chance that a pipe could fail, and include: pipe age, material, operating conditions and soil conditions, among other things. COF variables may include the pipe size, its location, environmental and social consequences of a rupture, interruption to service and tarnished public reputations.
For low risk force mains, screening and desktop evaluations such as hydraulic analysis and pressure management within the system are often enough to manage the assets. As risk goes up, however, utilities should look at higher resolution technologies that offer more confidence for higher predictability.
The SmartBall® Pipe Wall Assessment (PWA) tool is Pure’s best technology for identifying leaks, gas pockets and wall stress locations in metallic sewer force mains. PWA technology looks at pipeline walls affected by loading and bedding conditions, as well as other factors that cause stress on the pipe, including structural damage caused by internal or external corrosion. As the free-swimming SmartBall tool rolls through the pipeline, it collects both acoustic and electromagnetic (EM) data. The acoustic sensor is used to identify the sound of wastewater leaving the pipeline, or more often, the sound of trapped gas at the top of the pipeline. Trapped gas within a force main may lead to internal corrosion and eventual breakdown of the pipe wall which is the primary cause of force main failures. In addition to the acoustic data, the SmartBall platform also collects EM data to identify areas of the pipe wall that are under stress. Areas of the pipe wall with damage will be under more stress than areas with limited or no damage. Stress on the pipe wall can also be caused by other factors such as excessive loading and hard bedding surrounding the pipe. Recent developments in SmartBall technology now allow for the combination of leak and gas pocket surveys with PWA surveys in a single deployment, providing a complete screening tool for force mains. Based on initial surveys using the SmartBall PWA tool, areas where gas pockets overlap with stress anomalies represent the largest area of concern of force main owners, as it indicates a high likelihood of corrosion.
In force mains with a higher risk, utilities should also consider assessment with a higher resolution tool in addition to a pre-screening survey that detects anomalous changes. For lines that cannot be taken out of service, Pure can deploy the PipeDiver tool, which uses electromagnetic sensors to detect areas of damage along the pipeline. The inline inspection system is an innovative, free-swimming condition assessment platform specially designed for in-service inspection of pressure pipelines. Configured with PureEM™ sensor arrays, the tool can be used with precision to identify wire breaks in PCCP and broad areas of cylinder corrosion in metallic pipe.
While there is no silver bullet for assessing every pipeline, if a utility has a strong understanding of the risk and operational conditions of different areas in their system, an appropriate and defensible inspection plan can be developed. This process allows force main owners to develop a sustainable long-term strategy for managing their critical force main assets.
This notion came to life in a North American survey conducted in 2014 and published online this year in The American Water Works Association Journal on current sustainable infrastructure practices among water and wastewater utilities.
Authored by associate professor Amy Landis, the survey found that of the 125 American utilities that responded, less than half “failed to implement some form of sustainability practice, which ranged from renewable energy to infrastructure repair to demand management. Of the respondents, only 18 percent of utilities reported publishing a sustainability policy or vision.”
The results are rather surprising, considering that sustainable water infrastructure is critical to providing the American public with clean and safe water. The American Society of Civil Engineers (ASCE) gives drinking water and wastewater infrastructure a “D” grade, which puts the infrastructure in “poor and at risk” with most of the assets approaching end of service life, some reaching the age of 100 years old or more.
For combined water and wastewater utilities, the most common selected metric to evaluate sustainability practice was “water consumption and/or water delivery efficiency” at 63 percent. Coming in second for sustainable infrastructure practice was “employ trenchless pipe repair and/or rehabilitation.”
Buried assets are approaching end of service life, some reaching the age of 100 years old or more.
The good news is that it is easier today for public water utilities to move forward on the path to social, environmental, and economic sustainability. Modern inline technologies and precise data analysis tools certainly help the effort.
For more than a decade, Pure Technologies has played a key role in helping progressive utilities follow through with actions to promote sustainable practices for their water and wastewater infrastructure.
Sustainable practices include helping pipeline owners optimize capital and remaining useful life as they seek to more efficiently manage their assets.
As a trusted global leader specializing in the assessment, monitoring and management of pressurized pipelines, Pure has completed structural condition assessment on more than 8,000 miles of critical water mains. This has helped utilities avoid critical pipeline failures that can be expensive to remediate and damaging to their reputation. In addition, Pure has located more than 4,000 leaks on mains using inline leak detection. Through these activities, billions of gallons have water have been saved through repaired leaks and avoided pipe failures.
By understanding the operational conditions in their system, utilities can develop a defensible plan for managing their infrastructure.
The numbers continue to impress. Based on Pure’s condition assessment data, we have found that 96 percent of pipe sections do not have any deterioration at all and are in “like new” condition, while less than 1 percent of pipe sections require immediate repair. This is comforting information to utilities with aging pipelines still in operation, as is the case with the remarkable cast iron water main buried in 1831 beneath what is now Greenwich Village.
By identifying and repairing isolated sections that require intervention followed by a long-term management strategy, a utility can realize major capital program savings over replacement or large-scale rehabilitation. On average, a utility owner can proactively manage a pipeline for 5 to 15 percent of the capital replacement cost. The money saved can be invested to fix and sustain other parts of the system.
The U.S. EPA and ASCE estimate the funding costs associated with buried infrastructure ranges from more than $200 billion to 1 trillion over the next 25 years. The numbers are staggering. Pure Technologies is helping utilities manage their buried infrastructure through its Assess and Address™ approach to pipeline management, and as result, has saved clients hundreds of millions of dollars in replacement costs.
With drought, climate change and water conservation now part of the daily conversation, the pressure is on for public utilities to incorporate sustainable practices into their planning. It’s the right thing to do, from an economic, environment and social standpoint.
By having a strong understanding of the risk and operational conditions of different areas in their system, an appropriate and defensible inspection plan can be developed. This process allows utilities to develop a sustainable long-term strategy for managing their infrastructure well into the next century.
Water and sewer utilities across North America are facing a major funding gap related to their buried pipeline infrastructure. Based on current estimates, utilities do not have enough capital available to fix or replace their aging assets. In addition to the funding gap, utilities are under scrutiny because of increased incidences of pipeline failures that are disruptive to communities and expensive to mitigate.
This new reality has forced utilities to squeeze more remaining life out of existing assets, creating more demand for condition assessment programs that allow utilities to identify specific areas of damage and selectively repair pipelines in favor of full replacement.
Historically, condition assessment has been in the realm of a few specialized firms that respond to high profile pipeline failures; however, the industry has changed and condition assessment is becoming widely used and trusted. This approach has been adopted by many utilities that have successfully managed risk and extended the life of assets for a fraction of the cost of a replacement program.
According to a study by Pure Technologies, the majority of pipelines 16 inches and above can be cost-effectively managed for between 5 and 15 percent of the replacement cost. The study found that pipeline damage is typically not systematic across an entire pipeline, but is usually localized due to factors such as design, manufacturing, installation, environmental, operational or maintenance factors.
Equipped with this information, utilities can be assured that assessing the majority of their mains before replacement can reduce their infrastructure gap and extend the useful life of assets.
However, one question that often gets asked about condition assessment programs is how a utility should choose the right condition assessment solution.
The easiest way to solve this challenge is to employ a risk-based approach to condition assessment using a variety of tools that offer different resolutions.
Risk is a measure of the probability and consequence of uncertain future events, in this case, potential pipeline failure. A basic approach can be used to define risk even in complex systems; simply, risk is a product of Consequence of Failure and Likelihood of Failure (CoF x LoF).
Consequence of Failure (COF) refers to the damage a failure would cause based on factors like its location, the amount of users it supplies, and its size and operating pressure. Likelihood of Failure (LOF) refers to the probability of a failure occurring based on factors such as age, pipe material, soil conditions, operating pressure, failure history, among others.
Generally, the Consequence of Failure is well defined by the potential damage a pipeline failure would impose on the surrounding environment and is generally fairly static – or – once defined, it is unlikely going to change rapidly.
With this in mind the key to managing risk, or the possibility that a pipeline could fail, is in understanding the Likelihood of Failure. This can be achieved by quantifying the physical condition of the pipeline and understanding and quantifying the factors that affect the potential for deterioration of the assets.
Once risk is defined, the pipeline inventory can be prioritized which helps in the selection of condition assessment approaches and the application of the appropriate technologies. In general, high-risk pipelines warrant a detailed assessment while low risk pipelines can use lower resolution alternatives.
When selecting condition assessment techniques, qualifications and technical judgment should be used in lieu of price. High resolution tools come with a higher cost, but saving money on a low resolution condition assessment is not a responsible alternative for a high-risk main.
For example, the savings gained by selecting a low resolution technology for a large-diameter pipeline with a high CoF are often miniscule in comparison to the repair and capital programming decisions that result from the low resolution condition assessment data. If the data is inconclusive or inaccurate, a utility may unnecessarily invest millions in a capital replacement program that was not required, easily eliminating the savings achieved by selecting the less expensive condition assessment option.
Additionally, the cost of a failure should be considered when selecting a lower-cost assessment for a critical pipeline. The average cost of a large-diameter pipe failure is between US $500,000 and $1.5 million; money saved on lower-resolution assessments can easily be negated by the cost of mitigating a single failure and the resulting reputational damage.
One method of selecting a technology is to compare uncertainty to risk. As mentioned earlier, risk is a measure of the probability and consequence of uncertain future events. When dealing with a high-risk asset, it is important that the solution allows the utility manager to minimize the uncertainty of the condition assessment. More importantly, it is crucial that the utility manager knows the condition of the asset to the best extent possible, particularly in areas where there is a high Consequence of Failure.
Pure Technologies has a suite of condition assessment tools with different resolutions. Our low resolution solutions can provide basic condition data on leaks, air pockets and areas of pipe wall stress that could represent damage. This is a valuable prescreening option for high-risk mains, or alternatively for lower risk mains, can be enough detail for a utility to manage the asset.
Pure’s medium and high resolution tools provide more comprehensive data for higher risk pipe. Our high resolution tools can provide detailed accuracy, for example, locating small pits on metallic pipe. The data collected from both medium and high resolution tools is often used by utilities to create rehabilitation plans for critical mains.
Regardless of the solution provider, it is important that utilities employ a balanced, risk-based approach to condition assessment that uses appropriate tools. The most important factor a utility owner can remember is that there is no silver bullet to assess an entire system.
Comprehensive condition assessment of wastewater force mains provides significant challenges to owners/operators of collection systems as the ability to shut down or expose the pipeline for a thorough inspection is often impractical due to operational and/or financial considerations. Traditional gravity sewer inspection techniques (i.e. visual-based technologies) do not always transfer easily to their wastewater pressure pipe counterparts and visual assessments do not provide the structural condition of force mains – something that is critical in determining the true pipe condition. Therefore, a different set of inspection tools and assessment techniques is required for force mains.
The most effective strategy to safely manage a force main inventory is to implement a risk-based approach for any data collection, inspection, condition assessment, and management techniques. Using asset risk to guide the management strategies, an owner/operator can ensure they are implementing the right approach, at the right time, with the lowest financial impact. While recent advances in force main inspection technologies, assessment techniques, and repair/rehabilitation methods now allow for substantial extension of existing asset service life, a risk-based approach to their implementation will ensure resources are focused on the correct pipelines. The goal should always be to focus the proper resources in managing the asset while safely getting the most service life out of the force main.
Authors
Across the United States, there are thousands of miles of water and wastewater pipes buried beneath communities. These pipes come in a variety of materials and sizes, but all provide necessary services to customers across the country.
In recent years, several industry studies have warned that a large majority of these assets are aging and reaching the end of their designed lifespan. Although this is true, it is often prudent for municipalities to manage their assets – especially their large-diameter pipelines – in favor of replacement.
Replacement is expensive – industry experts estimate that the costs could reach $1 trillion over the next three decades. But beyond this massive expense are the unassailable logistical challenges of replacing thousands of miles of pipe.
Fortunately for municipalities, some pipe materials that make up the nation’s infrastructure have well-developed assessment methods that allow operators to determine the location of deterioration so that pipes can be renewed. Pipe deterioration is often due to localized problems – such as soil, loading and operating conditions – meaning pipelines do not fail systematically across their entire length and can often be effectively managed.
Unfortunately for some municipalities that own large-diameter metallic pipe, like Padre Dam Municipal Water District (PDMWD), the technologies available for assessing its condition have only recently been developed.
In November 2012, PDMWD wanted to assess the condition of a 1.2-mile (2-kilometer) stretch of 20-inch (500-mm) mortar-lined steel pipeline that was thought to be in poor condition and may need replacement. Before committing to the large capital project, PDMWD completed a non-destructive inline assessment using Mini PipeDiver®, a free flowing tool that can determine the baseline condition of metallic pipes.
The tool is equipped with PureEM™ technology and can detect broad areas of corrosion on metallic pipelines. While its resolution is not as high as other metallic inspection platforms, such as Magnetic Flux Leakage which can identify very small defects, PureEM is capable of detecting areas of corrosion that could lead to near-term pipe failure. It is also able to assess long distances in a single deployment, making it ideal for pipelines that cannot be removed from service.
Pure Technologies staff calibrate the Mini PipeDiver tool prior to inspection.
Staff extract the PipeDiver tool from the pipeline.
In total, the inspection identified six pipes with signals consistent with localized circumferential anomalies and 15 pipe sections showed signal shifts indicative of a pipe class change.
Starting in February 2013, PDMWD began validating the results of the inspection by excavating the six pipes with circumferential anomaly signals. All six anomalies were confirmed to have some level of defect including:
While the six anomalies represented different forms of damage, the information collected using PipeDiver was accurately verified and was very useful for PDMWD. In addition, the anomalies that indicate a pipe class shift provide the District with valuable information about their system that was previously unknown.
Based on the results of the condition assessment, PDMWD determined that a large replacement or renewal project was unnecessary and could be deferred. This allows the District to be confident in the condition of this pipeline while maintaining safe and reliable service for its end-users.
PipeDiver® – Free-Swimming Pipeline Inspection
Specifically designed for structural assessment of Prestressed Concrete Cylinder Pipe (PCCP) lines that are live or can’t be taken out of service due to a lack of redundancy or operational constraints.
Pure offers a number of leading edge technology options for assessing the condition of ferrous water and wastewater mains.
Industry reports also offer a bleak outlook about infrastructure in the United States; the American Society of Civil Engineers 2013 Report Card on America’s Infrastructure gave water and wastewater infrastructure a ‘poor’ rating and estimated that the cost to renew these systems would range from US $200 billion to US $1 trillion over the next 25 years.
While most of the discussion surrounding American water infrastructure involves pipe failures and the fiscal impact of renewal, water loss from leaking pipes is a major problem for utilities that often goes unnoticed. The U.S. Environmental Protection Agency (EPA) estimate that on average, between 15 and 20 percent of water never reaches the consumer, but is as high as 60 percent in some municipalities.
This loss accounts for a huge financial cost for operators in terms of billing and wasted energy used to pump and treat the water, but also represents the waste of a critical natural resource.
In places like Dallas, TX, managing water loss is an important matter for utilities, especially in the summer months when users are affected by severe droughts and forced to restrict consumption. The droughts also bring extreme heat and dryness which dries out the soil and causes pipes to shift. This can lead to the accelerated development of leaks.
To mitigate this problem, Dallas Water Utilities (DWU) has completed an annual summer leak detection program since 2004 on its large-diameter water transmission mains that range in size from 12-inches to 84-inches. The inspection program focuses on a variety of piping materials including Prestressed Concrete Cylinder Pipe (PCCP), Cast Iron Pipe and Ductile Iron Pipe.
To date, DWU has inspected 100 miles of pipe in the program, locating 120 leaks. This has allowed for a major reduction in water loss and helped ensure service reliability.
Pure Technologies staff insert the Sahara® tool into a live pipeline.
Water systems in large metropolitan areas are made up of thousands of miles of pipe varying in size; the distribution system, which delivers water directly to taps, is very large and features small-diameter pipe; transmission mains, which transport high volumes of water throughout an area, are made up of a smaller amount of large-diameter pipe. Because so many areas depend of these pipelines for supply and their high consequence of failure, maintaining transmission mains effectively is a high priority for operators. For DWU, the criticality of these pipelines was a major factor in adopting a leak detection program that focused on its large-diameter pipe.
According to a study completed by the American Water Works Association, leaks on large-diameter pipelines account for roughly 8 percent of the total leaks, but almost 50 percent of the total water lost from leakage. The discrepancy is created because transmission mains have a much higher capacity and operating pressure than distribution mains, meaning small leaks are actually leaking at a very high rate.
By focusing leak detection programs on large-diameter pipes, operators can achieve a much larger reduction in water loss by identifying and repairing evena single leak.
There are several methods of locating leaks on large-diameter pipelines. Non-invasive methods, such as correlators or listening sticks, work very well on small-diameter distribution mains but often lack the accuracy needed to address large pipes, as the sound of a leak does not travel as well as pipe diameter increases.
Conversely, inline leak detection methods aren’t well suited for distribution mains due to pipe size and complexity, but are very effective in accurately locating leaks on large-diameter transmission mains because they bring the leak detection sensor directly to the source of the leak, unlike non-invasive systems.
For inspection of its transmission mains, DWU uses Sahara® leak detection – a tethered platform that combines acoustic leak detection and inline CCTV – offered by Pure Technologies Ltd. The tool is non-destructive and is pulled by the flow of water by a small drag chute while the line remains in service. When the sensor is inserted into a tap, it remains tethered to the surface to allow for immediate confirmation of suspected leaks and gas pockets, internal pipe wall conditions and pipeline features by winching the sensor back and forth from the surface. The sensor is also tracked at ground level by a staff member, allowing for precise spot markings for excavations.
“Since introduction to Dallas’ program in 2004, Sahara technology has been a reliable tool for locating and eliminating leaks on larger diameter pipelines,” says Randy Payton, Assistant Director of Dallas Water Utilities. “The program allows the Department to plan and prepare the repair in lieu of responding to a failure.”
The tool is capable of locating very small leaks due the sensitivity of the acoustic sensor. In terms of reducing water loss, small leaks may actually represent the best opportunity for long-term improvement. Leaks on large-diameter pipelines typically form and mature over a period of decades. They tend to grow larger over time, up until a point where the pipe fails or the leak surfaces.
Locating and repairing a large leak prevents it from leaking for the “tail end” of its life, and from failing catastrophically. Catching a leak while it is very small does this as well, but also prevents the decades of sustained water loss that would occur as it grows into a large leak. Using technologies that can locate small ‘pinhole’ sized leaks can identify small leaks early on before they grow into larger leaks or lead to pipeline failure.
In the annual pre-planning stage, DWU identifies the ideal access points needed for the inspections based on their knowledge of the Sahara platform from previous years – there are usually about 30 insertions through 2-inch access points each year. Inspections are usually done during the summer months when most of the leaks are developing, and higher volumes in the pipelines allow longer distances to be inspected. DWU also controls the water flow closely during inspections to optimize the inspection distance. After many years of inspection, DWU staff has become adept at identifying the best insertion points and controlling the flow rate to maximize the tool’s capabilities.
During tethered inspections, there is significant traffic control required when the transmission mains runs beneath busy streets, since the tool is controlled and tracked above the ground by staff members. To avoid major commuter disruptions, the City will reroute traffic and thoroughly plan the insertions to avoid high traffic times – for example, inspections frequently start in the mid-morning when traffic slows as opposed to during morning rush hour. Beyond traffic control, staff from DWU and Pure will often work on weekends when downtown Dallas is less busy.
There are also unavoidable environmental challenges that require adjustments. Sometimes the water main will run under a busy highway or an environmental obstacle like a river, making it impossible for the staff member on the ground to track the tool and mark exact leak locations. In this case, the operator needs to review potential leaks more closely by winching the tool back and forth to determine the exact location.
DWU’s leak detection program has been extremely successful, locating 120 leaks in the 100 inspected miles. The estimated water savings from these leaks is about 7.2 million gallons per day.
The CIty has also seen a 17 percent reduction in catastrophic water main failures, likely as a result of the proactive approach in fixing leaks. Leaks, particularly in metallic pipe materials, are often a preliminary indicator of a failure location as it is a preliminary sign of distress. The reduction in failures has reduced property loss claims and service interruptions, as well as reduced treatment and delivery costs.
“Several factors affect the success of leak detection,” adds Payton. “After nine years, the utility continues to be impressed with its accuracy within the varied environments and piping materials.”
Through continued commitment to leak detection on its transmission mains, DWU is improving service reliability and saving significant amounts of water. DWU also completes regular structural assessment of its transmission mains to identify distress that could lead to pipe failure.
Pipeline Leak Detection Systems
Highly accurate inline leak detection systems that can detect leaks and gas pockets in operational pipelines. These systems are used primarily on larger diameter water and wastewater transmission mains of all materials as well as oil & gas pipelines.
Case Study: Dallas Water Utilites Leak Detection Program
Dallas Water Utilties anually inspects its large-diameter water transmission mains for leaks using Sahara® technology. Through DWU’s efforts in identifying and repairing leaks, about 7.2 million gallons per day has been saved and major failures have been reduced by 17 percent.
Each day, billions of gallons of water are lost worldwide. Not only does this represent the loss of a precious resource that not everyone has access to; it represents a massive amount of lost revenue for the utilities that provide it.
Each of the various pipe designs used in water networks across the United States has a specific life expectancy and operational requirements. Although some pipeline materials have well-developed, effective inspection technologies, assessing metallic water pipelines with mortar lining has historically posed a challenge for utilities, including the San Francisco Public Utilities Commission (SFPUC).
Without a reliable way to assess the condition of cement-mortar-lined pipelines, the San Francisco Public Utilities Commission set out to develop its own technology.
The third-largest municipal utility in California, SFPUC operates and maintains a large, complex water-delivery system for 2.6 million people and businesses in San Francisco, Alameda, Santa Clara, and San Mateo counties. The gravity-fed system reliably delivers water across the state without using energy-intensive pumping. Eighty-five percent of this water comes from the Upper Tuolumne River Watershed in the Sierra Nevada Mountains, where it’s stored in the Hetch Hetchy Reservoir and then transported 47.5 miles via the San Joaquin Pipeline (SJPL) across California’s Central Valley to the Bay Area. The SJPL system includes three large-diameter pipelines (56–78 in.), generally consisting of cement–mortar-lined steel that have been operating for more than 80 years. The pipelines can deliver 300 mgd.
To minimize the number of unplanned outages and determine the remaining pipeline life, SFPUC sought a technology that could assess the wall thickness of steel pipelines. Unfortunately, no technology was available, so SFPUC funded research to develop such technology. The project focused on SJPL. Because capital improvement funds were limited, however, SFPUC officials knew they needed a technology that would do the job and allow the utility to efficiently administer SJPL rehabilitation funds, according to Margaret Hannaford with the Hetch Hetchy Water and Power Project (HHWP), SFPUC.
In the August issue of AWWA Opflow, read about how SFPUC developed Magnetic Flux Leakage technology for reliable assessment of mortar-lined steel water pipelines.
Magnetic flux leakage (MFL) is an electromagnetic method of nondestructive testing that is used to detect corrosion, pitting and wall loss in lined and unlined metallic pipelines.
Case Study: San Francisco Public Utilities Commission (SFPUC)
Without a reliable way to assess the condition of cement-mortar-lined pipelines, the San Francisco Public Utilities Commission set out to develop its own technology. In a project from 2007 to 2010, SFPUC developed and used MFL technology to inspect its critical San Joaquin Pipeline.
The inspections are part of AWU’s proactive condition assessment program that focuses on leak detection and structural condition assessment through the use of advanced non-destructive technologies.
Focusing leak detection efforts on large-diameter pipelines is an excellent method to reduce Non-Revenue Water (NRW) and gather baseline condition information. While leaks on small-diameter distribution mains are the most common, leaks on large-diameter transmission mains account for a significantly higher percentage of the total water lost; repairing even one leak on a transmission main can achieve a significant reduction in NRW.
Identifying air pockets reduces pressure on pumps that are attempting to pump water past an air pocket. As pockets grow in size, they can adversely affect the flow and capacity of a pipeline.
In addition a reducing water loss, early identification of leaks helps reduce pipeline ruptures, as leaks are often a preliminary sign that a pipeline may eventually fail due to pipeline corrosion or loss of bedding support due to soil erosion. By identifying leaks early on, AWU is effectively reducing NRW, reducing their risk of failure, and gathering valuable baseline condition information on its pipelines.
The inspections completed in June 2013 were completed on two separate pipelines, the Ulrich 72-inch Prestressed Concrete Cylinder Pipe (PCCP) potable water transmission main and the Airport Road 24-inch C-303 Bar Wrapped Pipe (BWP) and Cast Iron potable water transmission main.
AWU used SmartBall® technology for both inspections. The SmartBall tool is a free-swimming inline leak detection platform that identifies the acoustic anomalies associated with leaks and air pockets that operates while the pipeline remains in service. The tool is tracked via fixed or portable receivers that are positioned strategically throughout the planned inspection distance. Following an inspection, the collected data is analyzed to determine if the acoustic anomalies represent leaks or air pockets and verified by AWU staff.
The Ulrich inspection covered a total of 6.6 miles in 6 hours and located no leaks or gas pockets. In order to successfully complete the inspection, AWU staff had to overcome one major operational constraint to ensure the tool could complete the inspection distance. Shortly after the insertion near the Ulrich WTP, the pipeline travelled beneath the Colorado River before making a 200-foot vertical climb, which can be difficult for free-flowing technologies without proper preparation. To overcome the challenge, AWU and Pure Technologies completed comprehensive flow simulations during the project planning phase to ensure the tool could traverse the vertical incline; this allowed the SmartBall tool to successfully travel up the steep hill.
In the Airport Road inspection, 2.4 miles of inspection was completed, successfully locating three leaks and giving AWU confidence that there are no air pockets restricting flow capacity in this line.
During both inspections, AWU and Pure Technologies worked closely to overcome operational challenges that allowed for successful leak detection surveys.
AWU supplies water to nearly 890,000 customers within and outside the corporate city limits of Austin, as well as the communities of Rollingwood, Sunset Valley, one water control and improvement district, five water supply corporations, seven municipal utility districts, and three private utilities. To ensure reliable service to its customers, AWU proactively addresses its infrastructure needs through regular inspection and rehabilitation to prevent service disruption and costly emergency repairs.
Pipeline Leak Detection Systems
Highly accurate inline leak detection systems that can detect leaks and gas pockets in operational pipelines. These systems are used primarily on larger diameter water and wastewater transmission mains of all materials as well as oil & gas pipelines.
SmartBall® – Leak Detection for Water Trunk Mains
SmartBall® is an innovative free-swimming in-line leak detection technology designed to operate in a live water mains.
Pure Technologies completed another successful year of its leak detection program with the City of Dallas and the Dallas Water Utilities (DWU) in July 2012.
This year, 16 leaks were found using Sahara® in just over 12 miles of inspection. The City and DWU are always efficient in repairing identified leaks, and since the conclusion of the 2012 inspection, have repaired about half of the leaks.
In 2004, DWU, which services 2.4 million customers in Dallas and nearby communities, began an ongoing proactive annual leak detection program using Sahara leak detection, though the DWU and Pure had been doing electromagnetic (EM) condition assessment since 2000. The leak detection program inspects pipes between 12-inches to 84-inches, and the transmission mains are made up mostly of Prestressed Concrete Cylinder Pipe (PCCP), but also feature Cast Iron Pipe and Ductile Iron Pipe. To date, approximately 86-miles have been inspected using Sahara.
The decision to implement an ongoing program with Pure stemmed from an internal study conducted by the City of Dallas of their large-diameter leak detection. The study found that it needed new technologies to improve efficiency.
Large-diameter water transmission mains in Dallas have a higher potential of developing leaks in the summer. Due to the high heat and lack of precipitation, the ground becomes extremely dry and hard, this shifts buried pipeline infrastructure slightly which can cause leaks to develop and ultimately water mains to break.
Sahara has been extremely effective in detecting leaks for DWU. Since the program began, 116 leaks have been found in DWU’s large-diameter transmission main network. The estimated water savings from all of the leaks detected by Sahara and repaired by DWU, is about 7.2 million gallons per day. DWU has also seen a 17 percent reduction in catastrophic water main failures since the start of the program; increasing service reliability.
Sahara® – Leak Detection for Water Trunk Mains
Leak and gas pocket detection using a tethered acoustic sensor allows for real-time results, and maximum control and sensitivity.
SmartBall® – Leak Detection for Water Trunk Mains
SmartBall® is an innovative free-swimming in-line leak detection technology designed to operate in a live water mains.
Underground pipelines are among the most valuable, yet neglected, assets in the public arena. They provide essential services such as supply of energy and drinking water and collection of wastewater. But we install the cheapest we can, bury it and forget about it – at least until something goes wrong. Then we are faced with having to fix the problem under emergency conditions, often considering only immediate needs and not the future operation of the pipeline in question.
This infrastructure must be seen as an asset, and managed as such. Properly maintained the pipe networks are valuable assets that are critical to delivering services to customers, and in any business the means of connecting product or service to customers is a major link in the business value chain. Not to maintain this network is negligent bordering on criminal.
Pipeline operators from around the world are discovering that simply replacing their aging pipeline assets is cost prohibitive and that advanced condition assessment services from Pure can help them confidently make informed decisions that drastically reduce capital and operating costs.
There are many ways in which a pipeline can deteriorate to a state of failure; countless sources of stress both inside and outside the pipe can take their toll.
Single-step blowouts of pipe walls are quite rare; pinhole leaks, hairline cracks, corrosion and leaking gaskets tend to occur first. Most catastrophic failures are caused by a sudden unexpected stress such as a water hammer acting on an existing weak point in the pipe. There is a widely held belief that the failure process is a simple one, where a pipe corrodes to the point at which it can no longer withstand the applied internal and external forces, resulting in a main break. However, research has shown that the failure process is more complex than expected. Corrosion plays a significant role in water main failures, but soil-pipe interactions, manufacturing techniques and human error are also important factors. Failures also take place in multiple stages rather than in a single episode. Early damage not only weakens portions of the pipe, it also allows water to escape, causing corrosion and washing out of the supporting soil.
Pipes at highest risk are typically constructed using dated materials or methods, running through an area with heavily vehicle traffic. Urban centers typically represent significant loss potential from damage caused by water main breaks as a result of high density buildings, underground infrastructure, important traffic thoroughfares, and economic loss potential of power, gas, water utilities and legal cases.
Older pipes that face stresses such as heavy traffic, construction activity, pressure transients or advanced age are more likely to fail. However there are other factors at work such as installation or material defects that may surface over a shorter period of time. The net result is that age alone can not be relied on as an indicator of a high risk pipe.
Prestressed Concrete Cylinder Pipe (PCCP) has a unique failure mechanism: high strength steel pre-stressing wires that provide strength to the pipe can become distressed and reduce the structural integrity of the pipe. Broken wires can be caused by physical damage to the pipe, corrosion, or hydrogen embrittlement. Regions of broken wires may be accompanied by leaks, especially in pipelines smaller than 48 inches in diameter, where the internal steel cylinder corrodes at the same rate as the wires or where water escaping through the joint encourages corrosion. Leakage has been proven to be a key indicator of structural condition in lined cylinder pipe, a type of PCCP in which the prestressing wires are placed directly on the steel cylinder. These types of leaks can create voids around the pipe and introduce added stress at an existing weak point.
Cast iron pipes corrode, become brittle and are prone to cracking. Many older North American cities have cast iron pipes that were installed in the 1800s, prior to the existence of pipeline standards, when methods of construction were not uniform and advanced quality control programs did not exist. Consequently, many pipelines were installed using what are considered poor construction practices by today’s standards.
Ductile iron pipes have failure mechanisms similar to those of cast iron pipes; however they become less brittle and consequently degrade at a slower rate. These pipes may be capable of supporting large leaks for longer periods of time without failing immediately.
Plastic and polyvinyl chloride (PVC) pipes are less prone to corrosion and less brittle than iron pipes. Failures in these pipes are often traced to leaking joints where the escaping water creates voids around the pipeline, causing unplanned stresses on the pipe.
Leadite is a sulphur-based joint-sealing compound commonly used in the 1940s and 1950s that appears to produce pipe failures due to the difference between its coefficient of thermal expansion and that of the metal in the pipes it seals. Leadite in pipe joints expands at a different rate than the pipe itself, causing added stress near the joints. This undesirable behaviour has resulted in particularly destructive joint ruptures on otherwise strong iron pipes.
Steel pipes primarily fail due to loss of integrity at welds, and external corrosion causing severe pitting and weakening the pipe wall. Both losses of joint integrity and through-wall corrosion pits lead to leakage long before failure. Older steel pipes in aggressive environments are capable of sustaining massive levels of leakage for decades before failing.
A significant percentage of the United States force mains have been in use for several decades and never been assessed or proactively managed. To safely rely on these pipelines, their condition should be periodically checked to ensure there are no locations susceptible to failure.
In addition, many wastewater agencies are faced with EPA consent decrees that require condition assessment of force mains. As a result, many agencies are now faced with the daunting task of assessing their sewer force mains—a task that until recently was often not feasible due to operational constraints. However, Pure Technologies continues to improve technology and can now obtain a realistic assessment of a force main within the common constraints of most wastewater agencies.
In case of emergency+1 (905) 624-1040
Webinar Series: Tackling Metallic Transmission Mains
White Paper: Risk-Based Approach to Condition Assessment
Case Study: City of Montreal, Quebec
Case Study: K-Water, Tongyeong City, South Korea