Water Pipeline Condition Assessment

MOP 134 provides water utilities with an appropriate path for adequately determining the structural status of an individual transmission pipeline or pipeline system.

Many water utilities have only a limited knowledge of the structural condition of their underground assests. In order to maintain optimum serviceability, it is increasingly important that utilities gain a better understanding of the current condition and performance of these buried assets. Regular inspection and condition assessment of pipelines can greatly assist utilities with developing robust and cost-effective operational maintenance programs, which will optimize capital expenditure whilst minimizing risk. The aim of the project was to conduct a state-of-the-art literature review of non-interruptive condition assessment inspection devices for large diameter transmission mains (greater than 12 inches). In addition, an expert panel workshop was to be held to review business needs and drivers, the performance of existing technologies, and future underground asset condition assessment research needs. Originally published by AwwaRF for its subscribers in 2004.

Water and wastewater infrastructure are a somewhat invisible, yet critical, part of modern life. Incredibly, many buried assets have been in service for 50-100 years and are still in good condition. Conversely, other systems fail well before their predicted design lives, causing property damage, injury, and even loss of life. In many cases, early detection could have prevented catastrophic failure, and understanding the state of underground infrastructure has become a key priority for many municipalities. Industry has responded with a number of new and innovative technologies for condition assessment, however, understanding these tools can be difficult, as many vendors treat their proprietary systems as trade secrets. Water and Wastewater Pipeline Assessment Technologies: Classification Systems, Sensors, and Results Interpretation provides a thorough guide to the technical workings of some of the most popular water and wastewater assessment technologies available, including CCTV crawlers, acoustic listening devices, laser sensors, 360˚ video cameras, pipe penetrating radar, and more. Features: Presents an overview of current technologies in CCTV inspection, including next generation video formats, high-definition resolution, and fisheye/sidescan technology. Provides helpful tips and tricks to cut through technical jargon and identify the technological specifications to compare between multiple vendors. Examines the pros and cons of competing technologies including laser and lidar, and provides an overview of unique approaches such as Pipe Penetrating Radar, Focused Electrode Leak Location, and more. Highlights the importance of coding standards, data management, and software tools that can be leveraged to create a successful asset management program. Water and Wastewater Pipeline Assessment Technologies: Classification Systems, Sensors, and Results Interpretation provides a mixture of theory and real-world, practical considerations ranging from deployment tips and data exchange formats to the technical limitations of different technologies. The book is a valuable resource for municipal employees, project engineers, and others involved in designing and implementing major inspection programs.

The interruption of water supply service during inspection of large-diameter transmission mains can have undesirable impacts on drinking water utilities and their customers. Likewise, the failure of a large transmission main can disrupt the supply of water to a large portion of a community, causing significant inconvenience and damage. Therefore, regular inspection of mains can assist utilities with preventative maintenance and minimize risks. Typically, utilities conduct condition assessment of buried pipes to determine a pipeline & rsquo;s serviceability and to consider if a new main or rehabilitation are needed. In the past, many condition-assessment methods involved the excavation and removal of pipe sections. Nondestructive evaluation techniques were rarely used or thought of as viable options. In addition, utilities were unable to use existing condition-assessment technologies for lines in service due to constraints and limitations, such as water levels in the mains. New technologies appear to offer some hope for an effective and affordable solution; however, details of these technologies may not be widely known. Consequently, the industry needs further evaluation of condition-assessment technologies that are capable of being used while maintaining service to the main.

The development of economical tools to prioritize pipe renewal based upon structural condition and remaining asset life is essential to effectively manage water infrastructure assets for both large and small diameter pipes. One tool that may facilitate asset management is a condition curve. A condition curve is a graphical representation of the condition of a pipeline versus time. This report provides a review of the state-of-the-technology for structural/physical condition curves for water mains. Various models are summarized such as break frequency curves, deterioration/decay/survival curves, condition rating curves and condition rating indices, and serviceability/performance curves. This report also provides new case study information on how condition curves are used by utilities for managing their water infrastructure based upon a survey of nine utilities. The utilities that were surveyed for these case studies used methods that ranged from very detailed asset management programs that combine inspection, monitoring, and test data with their pipeline condition assessment program to simple analyses of pipe break history to prioritize pipeline renewal activities. The review also discusses short-term and long-term research needs for further development of a performance-based buried infrastructure asset management approach to improve the quality and quantity of data used by all utilities.

Water utilities often do not know the specific cause of external corrosion observed on their water mains, and consequently, the chosen preventative measure may not work effectively. Historically, these choices are based on data from other industries (e.g., gas and oil) and may not be suitable for the water industry. Corrosion of metallic pipes can be caused by a variety of mechanisms, each of which requires a different solution. Determining which corrosion mechanism is at work is not a simple matter, because the resulting pipe damage looks similar for all of them. The failure to properly identify corrosion sources may produce prevention systems that are ineffective or do not last. For example, it is not effective to install an anode bag on a main that has a bacteriological corrosion problem. Similarly, an anode bag installed to reduce corrosion caused by a stray impressed current would be quickly used up and would provide only short-term protection. Much recent research on corrosion has focused on internal corrosion, primarily related to water-quality issues, such as lead and copper control and red water. This project will examine external corrosion, which affects the structural integrity of the pipe and makes it vulnerable to leaks and breakage. After identifying the causes of external corrosion, the study will find economical solutions for each type of corrosion and verify them through field trials.

This manual provides technical information to aid utility managers and engineers in making informed decisions, along with practical information about how methods can be deployed.