Pipelines 2017: Condition Assessment, Surveying, and Geomatics

Pipe penetrating radar (PPR) is the underground in-pipe application of ground penetrating radar (GPR), a non-destructive testing method that can detect defects and cavities within non-ferrous (reinforced concrete, vitrified clay, PVC, HDPE, etc.) pipes. The key advantage of PPR is the unique ability to map pipe wall thickness and deterioration including voids outside the pipe, enabling accurate predictability of needed rehabilitation or the timing of replacement. This paper presents recent advancement of PPR inspection technology together with selected case studies. The century old Broadway sewer main in Everett, WA, is a combination of a 30” reinforced concrete (RC) pipe and a 36” brick pipe. Little information is known about the condition of these pipes and the owners needed structural information beyond the usual closed circuit television (CCTV) in order to plan long term management of these critical assets. Over 16,000 ft of high resolution PPR line data were collected via robotic inspection. Due to the highly complex nature of the geophysical data, data processing and interpretation was a critical component of this project. The PPR results revealed that there are variations in the rebar cover in segments of the RC pipe. Although the average minimum rebar cover (depth of the first layer of rebar measured from the inner surface of the pipe wall) in almost every pipe segment appears to be sufficient (more than 0.75"), local anomalies occur along the pipe. No voids were detected outside the concrete pipe. In the second case study PPR was used for the condition assessment of asbestos cement (AC) pipes. AC pipes form a significant component of the water distribution and sewer collection systems in many cities. A majority of these pipes appear to be approaching the end of their useful life. The ability to accurately and cost-effectively assess the wall thickness of asbestos cement pipe has become a critically important issue for pipe owners. A new, high resolution PPR system, the SewerVUE AC Pipe Scanner (ACPS) was developed and successfully deployed in a live 10” AC pipe in Surrey, BC, Canada. Using new, high frequency antennae, the PPR inspection accurately mapped the remaining wall thickness.

The San Diego County Water Authority has been using acoustic fiber optic (AFO) systems to monitor prestressed concrete cylinder pipes (PCCP) in real-time since 2006. Currently, the Water Authority has seven AFO systems monitoring 37 miles (60 km) of PCCP, which has captured over 1,400 distinct wire break events. The Water Authority has spent a significant amount of capital and operating resources to install and maintain this system, totaling over $13 million since 2006. This paper will discuss the Water Authority’s history with real time pipeline monitoring, the total costs of monitoring, analyze the payback period for the monitoring costs, and the several benefits to the Water Authority. The benefits include savings due to reduced pipeline shutdowns and associated labor, PCCP inspection savings, deferred rehabilitation based on defensible data, proactive failure response based on the data, and the value of wire break frequency information to make critical decisions.

This paper describes the development and successful applications of a closed circuit television (CCTV), LiDAR (Light + radar) and sonar based pipe inspection system that is robust to gather quantitative data for critical underground pipe condition assessment. The system that can be deployed on a ROV or on a float produces accurate cross-sectional analysis and sediment volume. This capacity is increasingly critical in large diameter pipes with high level of flow. The system employs a time of flight LIDAR that is sub cm accurate. Results from recent projects are discussed in detail. The North Surrey Interceptor in Surrey, British Columbia, Canada, is a critical line in the municipality’s wastewater system. This reinforced concrete box culvert is 1500 mm × 1750 mm, and often operates at full capacity. The owner has experienced failures on this pipe, and it was recently rehabilitated. The sonar results provided accurate sediment volumes and cross sectional restrictions. This information was used to infer the location of defects and gather the necessary information for a subsequent pipe penetrating radar (PPR) deployment. The TEES Tunnel in Tolo Harbor, Hong Kong, is a 7-km long, 3.18-m diameter reinforced concrete sewer tunnel. It has been in service for 15 years and was in need of a quantitative condition assessment. Due to safety concerns man entry was not an option. A long-range multi-sensor robot was deployed to traverse 1 km from both access portals and to gather CCTV and LiDAR data. Due to limits to flow diversion the project had to be completed in a 24 hr time frame. The CCTV and LiDAR data revealed quantitative information on the condition of this critical tunnel. Advanced pipe condition assessment technologies, such as the CCTV, LiDAR and sonar system described in this paper are cost-effective, non-destructive methods that are able to help better refine estimated remaining life of an interceptor, accurately determine overall severity of pipe degradation, as well as provide a basis for improved cost allocation and timing of rehabilitation efforts.

In the 1990s the failure of prestressed concrete cylinder pipes (PCCP) became more common and owners looked for solutions. At the time, options were limited and owners were often faced with full-scale pipeline replacement. This need was further fueled by the catastrophic nature and impact of the failures combined with public pressure for action. As budgets tightened and pipelines continued to age, the need for a better way to evaluate and manage these pipelines became apparent. This eventually led to many changes in the industry including the development of several condition assessment tools, technologies and techniques. Today, owners have access to a wide variety of options for condition assessment tools, technologies and, in combination with asset management, can make informed decisions and manage pipelines more efficiently and effectively. Electromagnetics for the assessment of PCCP was among the first of the technologies developed for inline assessment of water pipelines. On-going developments have produced an array of inline inspection tools using electromagnetics including physical entry carted applications, free-swimming tools and robotics platforms. Testing, research and experience in the data collection, analysis methodologies, and calibration and verification exercises have further improved the understanding of the data. Recent advances have been made in the technologies for their application and use in metallic pipelines. This paper reviews the advancements in electromagnetic inspection platforms and analysis techniques on PCCP and the eventual adoption of the technology for metallic pipes. It will include a historical look at the industry and the possible future advancements.

The $2.3 billion I-4 Ultimate Public Private Partnership (P3) improves 21 miles of Interstate 4, a major interstate through downtown Orlando. Over 12 wet utility agency owners (UAOs) have water, sewer, or reclaimed pipelines impacted by the project. This paper describes the interesting and unique trenchless, cured in place pipe (CIPP) rehabilitation, and relocation situations that Jacobs overcame on the northern half of the project. The new interstate is not only being reconstructed, but also being elevated nearly 30 feet with additional fill in certain areas. The utility impacts ripple out onto major side roads over a mile in some cases. Most relocations were created by direct conflicts with new stormwater pipes, structural retaining walls, or the road itself. In other cases, indirect conflicts were created by the additional loading to aged gravity sewer pipes, aged water mains and forcemains, and casings. In addition to the direct conflict relocations, the design team carefully evaluated pipe rehabilitation, pipe replacement, and casing thickness requirements for the indirect conflicts. Ultimately, the team developed engineering approaches that were acceptable to our design build partner, the UAO, the Florida Department of Transportation, and Florida Department of Environmental Protection.

The San Antonio Metropolitan area has experienced sustained growth for decades, putting increased pressure on existing wastewater infrastructure. In June 2013, the San Antonio Water System (SAWS) approved a settlement agreement with the U.S. EPA that requires significant improvements to the SAWS wastewater system over a 10-year period to reduce sanitary sewer overflows (SSOs). This work includes the targeted replacement and rehabilitation of an aging infrastructure system that consists of over 5,200 miles of sewer pipe. One such pipeline is an existing 48-inch concrete trunk sewer, which operates at capacity during dry periods, but and experiences SSOs of 50,000-100,000 gallons or more during periods of minimal rain. SAWS has identified the replacement of this critical sewer pipe as one of its highest priorities, initiating design of a six-mile segment of 60- to 78-inch sewer pipe to increase the current capacity. The project is to be delivered on an expedited schedule, and there are several challenges including an alignment through a U.S. Military Installation and two major hospital complexes, extensive tunneling, and close proximity to a major creek. This paper will focus on design approaches used to expedite project delivery. In all decisions, delivery time and reduction of SSOs were key considerations. Examples of schedule cutting strategies include dividing project into two segments, use of existing right-of-way and easements to eliminate need for condemnation, constructing the new 78-inch line parallel to the existing 48-inch line to nearly eliminate the need for by-pass pumping, and a radical shift in the standard plan review/approval process at SAWS. In summary, the project has been delivered on schedule and is presently under construction.

Some water utilities have been exploring a variety of techniques to fight external corrosion and to preserve the value of their buried assets however a standardized and defensible approach does not exist. This project will investigate technical and economic considerations to retrofit buried metallic pipelines with CP. The water utility industry is inherently different as compared to oil and gas pipeline industry. The water utility industry is not regulated or required to apply cathodic protection to its pipelines. Application of cathodic protection in the water utility industry is elective and only for the purpose of leak rate reduction and asset preservation. Hot spot and retrofit applications of cathodic protection are typical in the water industry to control leak and break rates. Hot spot cathodic protection is and operations and maintenance driven procedure of installing a galvanic anodes directly connected to metallic pipes at the location of a pipe failure during the pipe repair activities. These anodes are installed without any means of monitoring and stay in the ground until total depletion, usually without replacement. Retrofit CP refers to the practice of systematically protecting existing pipes with galvanic cathodic protection after construction. The on-going water research foundation project (WRF # 4618) included a literature survey, corrosion industry and water industry workshops at major conferences, collection and analysis of utility case studies from U.S. and Canadian utilities, and development of a CP hot spot and retrofit guidance manual to assist water utilities in achieving economic savings and extending asset life. The goal was to produce a utility focused design criteria manual, standard specifications, drawings, and financial template/methodology that will provide a consistent financial benefit measurement of the value of the anode hot spot and retrofit programs. In this paper, a summary of the research and analysis is presented along with supporting case studies.

Water and wastewater systems throughout the USA utilize pump stations, gravity pressure flow, and piping layouts that vary in total system efficiency, reliability, and longevity. Pumps and piping systems are often mismatched, suboptimal, and lacking in overall maintenance/operational efficiency. Piping schemes typically have wide fluctuations in elevation, pressures and flow rates. The results of these variables is that air pockets form in piping systems that can decrease the pipeline efficiency resulting in increased pumping costs, longer pump running times, and an increase in pump wear. Additionally, pressure transient (up-surge and down-surge) events occur countless times each day, and the results of these pressure transient events include pipe bursts, pipe collapses, and massive shocks to the piping systems and their components. It is estimated that air in pipelines results in a minimum of 10% increase in pumping costs–purely from the air pockets present in virtually every pumping/pipeline. The Energy Star Program of the EPA estimates that about $4Billion is spent annually in the U.S. alone for energy costs to run drinking water and wastewater utilities. If the sector could reduce energy use by just 10% through investments in energy efficiency collectively it would save about $400 million annually. Properly applied and installed air valves have been proven to reduce energy costs by an average of 10%, as pump run times are decreased, and the energy required to pump the same volume of water/wastewater is reduced as the air is evacuated. Three Case Studies are presented: 1) In Denton County, Texas a lift station and force main with five air valves was experiencing flow rates well below the pumps rated capacity and pump run times of forty-five minutes or longer. Two of the existing air valves were replaced with new air valves and pump rates went from approximately 100 gpm to over 400 gpm and pump run times dropped from an average of 35 minutes to an average of 10 minutes. 2) In Nairobi where the addition of air valves to a water transmission system increased flow rates from 68 MGD to 82 MGD. 3) In Uganda where flow rates increase from 595 GPM to 660 GPM in a water transmission system through the addition of air valves. Through this paper and presentation, A.R.I. USA will share the processes and engineering utilized to correct the energy usage problems associated with air and gasses in pipelines and solutions for improving performance of the pipelines.

The City of Ottawa is a municipality of 960,000 people that owns and operates its own watermain and sewer infrastructure. The City has developed industry-leading comprehensive asset management strategies for its pipe infrastructure. A key element of the management strategy for its critical pressure pipes-the large-diameter watermains (24 in. to 78 in.) and sewer force mains (all sizes up to 42 in.)-includes mapping. Pipeline mapping is a useful tool for addressing distress and managing the asset. However, when trying to correlate internal pipe conditions to above ground coordinates, a number of challenges arise, particularly when defects are identified as a part of the condition assessment. In order to effectively intervene on a distressed pipe, it is critical to be able to locate and excavate that pipe with certainty. Errors in mapping can lead to erroneous excavations, costing the City valuable time and money. In order to overcome this challenge, a variety of technologies and methodologies have been utilized to map the City’s pipelines. To date the City has completed over 24.2 mi of 2-dimensional mapping using a combination of above ground GPS points and internal pipe data collected as part of the condition assessment work. Different inline inspection tools were used to collect the data required to create the maps, including tethered and free swimming tools, depending on the inspection requirements. This paper will discuss the methods used to create the GIS data of the over 24.2 mi of pipeline; the benefits to having the mapping data; lessons learned while trying to use the map; comparisons between the inspection GIS and the City’s GIS; as well as overall challenges with mapping pipelines in general.

Models and tools are an essential part of the advanced asset management process, which provides informed decision support for management of drinking water, wastewater, and stormwater infrastructure. Various models and tools for infrastructure asset management are described in the literature. However, most of the proposed models fail to document the understanding of the system they are modeling or the reliability when applied to the real world practice. The models in literature were created with limited datasets, and there is a significant lack of methods and tools to verify and validate these models. This lack of the reliability documentation is hindering the implementation of these models in practice. This paper presents the framework developed for the PIPEiD National Database and Modeling Platform for the validation and verification of the models and tools for water infrastructure asset management. Practical applications of evaluating the existing models and tools with the proposed framework has been piloted. Field, experimental data has been collected from 30 participating utilities. This collected data has been applied in the proposed framework to document the accuracy of various models and tools for real world applications.

Valley METRO used three delivery methods to build the first three light rail transit (LRT) segments in the Phoenix metropolitan area. Central Phoenix East Valley, completed in 2008, used a conventional Design-Bid-Build approach. However, Northwest Extension and Central Mesa Extension, which were finished in 2015 utilized a Construction Manager at Risk approach and a Design-Build approach, respectively. Utility relocation is an essential part of LRT system construction, where the alignment is located in an existing road right-of-way. The project delivery method impacts both the design and the construction for utility relocation in many ways. Three notable areas of differences are potholing, schedule and partnering. Using examples from each LRT segment, similarities and differences in impacts for each delivery method, are analyzed from a designer’s perspective.

Civil integrated management (CIM) modeling, which is an extension of BIM, entails the creation of a geometric 3D model of a feature that is combined with its attributes. CIM is often started by fitting simple geometric shapes to a 3D point cloud. Terrestrial LiDAR is a proven surveying technique for generating accurate point clouds for CIM models. Employing photogrammetric principles, structure from motion (SfM) is able to produce 3D point clouds similar to LiDAR from a set of overlapping images, such as those collected by a UAS. This paper explores the use of the UAS-based photogrammetry and assesses the performance of consequent CIM models compared to LiDAR for surveying a construction site with numerous above ground pipes. Cylindrical shapes are automatically fit to the sections of point cloud with pipes in both the LiDAR and SfM, then the geometry of models are compared to tape measurements. The results show that pipe models extracted from SfM have less consistency in diameter and fit quality. This study indicates that the UAS-based SfM can be an alternative to extract pipeline models; however, special care should be given based on the application and the accuracy requirements of a project.

The objective of this project is to collect, compile and analyze high quality field data on pipeline reliability performance for water pipelines of different materials. This project will be completed in two phases: Phase I will include the data collection from the United States Bureau of Reclamation (USBR) and their 17 Western States, as well as the U.S., Canadian, and Australian Water Utilities for different materials including cast iron, ductile iron, reinforced concrete, steel, pre-stressed concrete, PVC, AC, and others. Canadian and Australian utilities’ data and knowledge will be stored as a subset of the national pipeline database. Phase I will also include the development of a Web-based, GIS-enabled water pipelines database to aggregate and standardize the collected data, and further to identify the missing data deemed critical to understanding water pipeline performance. These tasks will be geared to meet the Phase II objectives of collecting and/or generating the missing data, and the establishment of an understanding of the general state of buried water pipeline infrastructure, failure rates, general effectiveness of corrosion control measures, and the calculation of failure rates for each water pipeline material. Virginia Tech will protect data and database as per federal requirements under export-import control law. The proposed research has the following five objectives: Developing a standardized data and metadata structure for verifying, storing, updating, retrieving, and exporting/importing water pipeline infrastructure attributes; Creating a GIS-driven Web-based platform for developing, analyzing, validating, implementing, and benchmarking of models and tools for pipeline asset management; Piloting of PIPEiD with utilities of various sizes across the U.S. for demonstration; Establishing a protocol for water pipeline data security, sanitization, and publication; and Developing a plan to promote and sustain effort by engaging the water industry. This paper presents the national effort for water pipeline data collection and compilation methodologies. This project will determine the state of the knowledge in water utilities, other industries, and large Internet of Things (IoT) firms to lay the groundwork to identify key issues that can be addressed by data collection and big data analytics for water pipeline infrastructure systems.

Efficient and reliable methods of canal inspection are necessary for supporting the maintenance decision-making. One focus of such decision-making is predicting and preventing water losses in a canal system by identifying cracking sections of concrete canal facilities. Current practice requires engineers to spend much time and money on a visual inspection and engineering surveying for identifying sections of canals that are subject to water losses. Such manual efforts could hardly achieve detailed assessment of underwater conditions of canals. Emerging imaging technologies, such as terrestrial and mobile laser scanning can collect high-resolution spatial data for supporting detailed condition assessment of canal facilities. Unfortunately, terrestrial and underwater imaging systems are expensive and tedious to use for mapping a large canal system, considering both the time and costs for high-resolution imagery data collection and processing. For example, maintaining Salt River Project (SRP)’s 131-mi canal system with mobile and terrestrial laser scanning can cost thousands of dollars every day, and even more time and money for hiring professionals to process terabytes of 3D imageries. This research examines an integrated analysis method of aerial and terrestrial imagery data to reduce the time and costs for mapping water losses of a canal system without compromising the comprehensiveness of the inspection. The method first applies remote sensing techniques to process satellite images, which are much cheaper than terrestrial and underwater laser scanning, to extract typical environmental features along canals, including land surface temperature (LST), humidity, and plant cover index. The algorithm then analyzes spatiotemporal changes of those features along the canals and identifies sections of canals that are more likely to have water losses (e.g., sections that have a lower temperature and higher humidity than adjacent sections). Terrestrial and underwater laser scanning then can get detailed data to inspect those anomalous canal sections. A case study shows the potential of the proposed two-stage approach that uses both satellite and terrestrial imageries for efficient and effective water loss mapping of a large canal system.

Existing utilities can present large risks to projects of every kind, including design-build projects. One need not look any further than recent news releases to get a sense of the cost and time issues that can happen. The Honolulu Star-Advertiser states: “Years before utility line clearances posed the “most significant risk” to Honolulu rail, key project consultants downplayed Hawaiian Electric Co.’s warnings of a potential problem and stated that the plans they were developing should be OK.” ENR states “The I-405 expansion was Caltrans’ first design-build project. … utility maps for the Sepulveda Pass caused some of the delays on I-405.” There have also been some successes in managing utility risks. Given the wide range of practices for managing utility risks on projects, ASCE, NSPE, and ACEC in 2016 updated their EJCDC Design-Build master contract document set to include guidance on contractual language for utility investigations. This contractual language includes as a basic engineering service the projects’ use of ASCE 38, Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data. When coupled with an understanding of successful utility coordination processes and project sequencing, these two documents form a good framework for conducting utility investigations on design-build projects. This paper will illustrate how the use and sequencing of utility investigations as delineated in EJCDC contracts and ASCE 38 assists in reducing utility risks on design-build projects through examination of several large projects: Seattle’s Alaska Way Viaduct project, the North Tarrant Express and LBJ Managed Lanes Projects, and Houston’s Grand Parkway Project.

The San Diego County Water Authority operates and maintains the San Diego region’s aqueduct delivery system, which consists of approximately 499 kilometers (310 miles) of large-diameter pipelines, more than 1,400 aqueduct-related structures, and over 100 flow-control facilities. These facilities occupy approximately 567 hectares (1,400 acres) within the Water Authority’s right of way, and deliver water for over 3.3 million residents. With a significant proportion of its infrastructure approaching the end of its useful life, the Water Authority embarked on an effort to strategically manage its assets over the long term through its asset management program. This commitment will ensure it maintains its mission of providing a safe and reliable supply of water to the San Diego region via its 24 Member Agencies. This paper examines the Water Authority’s strategy to gather comprehensive condition assessment data on its most critical pipes. Using this data, the Water Authority aims to have sufficient confidence in its pipeline transmission system to ensure a satisfactory measure of reliability. The paper also explains how confidence ratings are included in performance metrics, specifically an asset management scorecard.

Statistical models used in predictive analytics are becoming prevalent in numerous research capacities. The present paper extends several of these models to analyze water distribution pipe breaks in a municipality, with future break expectation as the desired outcome. In particular, the present research examines the use of tree-based methods to model the occurrence of pipe breaks. Such approaches include classification trees and ensembling methods such a random forests and gradient boosting. A challenge faced by some utilities is the scarcity and uncertainty of system-specific data system (age, size, pressure etc.). The presented methodology tackles the issue by using only open-sourced data, focusing on the demographic and environmental factors that drive pipe failures. 51 months of pipe break records were obtained from a utility in the mid-Atlantic region and cross validation holdouts show that a 10-variable gradient boosted ensemble of classification tree’s is the most effective predictive model. Finally, inferences between individual predictors and how they affect break expectation were evaluated through partial dependencies.

The majority of U.S. utilities are small, serving populations of less than 15,000. These utilities must meet all NPDES permit requirements yet with fewer resources, both financial and human. This paper will consider how innovative GIS cloud based data and mapping technologies can be combined with small utility asset management planning and professional engineering services to enable small utilities to affordably begin or take the next step regarding risk analysis based condition assessment and rehabilitation. The Sewanee, Tennessee Utility District (SUD) will be used as a case study. For the past year SUD has been relating key data, photographs, videos, condition assessment conclusions, rehabilitation recommendations, pricing and scheduling using simply edited Google Map based GIS technology. All data is related to particular SUD assets without SUD needing to own any database, mapping or asset management software. This enables SUD to afford to manage and sustain their utility with existing capabilities.

After experiencing multiple pipe breaks in a single area, the staff at The Las Vegas Valley Water District (LVVWD) began to suspect that pressure transient events were to blame. Though the District has one of the most sophisticated SCADA systems in the country, there was no direct evidence of significant transient events. The data provided by the traditional pressure monitoring equipment could not validate their suspicions. With the aim of getting more detailed pressure data, the District deployed a series of high sample rate pressure monitoring devices. Almost immediately the highly granular data not only confirmed their suspicion that transients were wreaking havoc, but revealed pressures nearly twice as high as what they had been capturing with their traditional data monitoring system. This case study reviews how LVVWD utilized the high sample rate pressure data to calm their systems and eliminate the source of damaging transients.

RFT is an established technique for the inspection of a wide range of tubular applications, including water and waste water pipelines (“mains”); however, there are always some pipes that cannot be inspected with RFT (or other NDT methods) due to a number of elbows, vertical sections and access from only one end. For short lengths of un-piggable pipes in plants or field, robotic crawlers can help. HiBot has developed a unique robotic crawler that has been “married” to Russell’s I-PIT RFT Tool making difficult inspections possible. This paper describes the two technologies.

Government of India has taken various initiatives with an objective to make the holy rivers pollution free. This requires a systematic and holistic strategic plan involving a large number of stakeholders to accomplish the vision. Technical Assessment study for pollution abatement in the holy rivers from one of the heritage towns has been carried out. The condition assessment of existing sewerage and affected natural drainage system of the city has been carried out and attributed in GIS platform. The Technical Assessment included analysis of a condition assessment survey (CAS) of affected natural drainage system, sewer network, pumping stations, rising mains and sewage treatment plant along with disposal system. Various alternatives were planned and designed considering augmentation, rehabilitation of existing or proposal for new assets in lieu with centralized and de-centralized systems. Detailed cost-benefit analysis for each alternative was carried out to derive life-cycle cost (LCC). The analysis included capital expense (CAPEX) with operational expense (OPEX) for 15 years along with various revenue generation options such as opportunity cost for land released by constructing new assets with advance technology, selling of recycled water for non-potable uses, industrial and irrigation use. The selected alternative is being considered for implementation of works under public-private-partnership (PPP) mode. The onward steps being taken up are river front development comprising landscaping, urban development, recreational activities and improved tourism.

This paper discusses the capabilities and limitations of current laser profiling technologies for pipeline condition assessment and rehabilitation design, and introduces the next generation of georeferencing lasers. A recent case study for which the georeferencing laser was deployed is presented, with lessons learned and key takeaways.

Kirkwood Penstock is a unique pipeline structure that was constructed on a steep mountain side and conveys water from Canyon Tunnel to Kirkwood Powerhouse. Kirkwood Penstock is owned and operated by the San Francisco Public Utilities Commission (SFPUC), the third largest municipal utility in California, serving 2.6 million residential, commercial, and industrial customers in the Bay Area. Eighty-five percent of the water delivered to the SFPUC customer must be conveyed through Kirkwood Penstock. Kirkwood Penstock is part of the SFPUC’s Hetch Hetchy Water and Power (HHWP) Project. HHWP is a division of the SPFUC.

Cobb County Marietta Water Authority (CCMWA) has a large diameter transmission main loop carrying water around its jurisdiction. The loop is 75 miles long, with 36 to 54-inch diameter sizes, both ductile and PCCP materials. Undertaking leak or condition assessment inspections of the full length of the line is cost prohibitive. However, by accurately monitoring water pressure at various points along the loop, it was believed that CCMWA could identify transient events occurring in the system and locate them, so that appropriate responses and actions could be taken. This case study outlines the methodology CCMWA undertook, the type of data they collected, the types of events they were able to identify when monitoring pressures at high sample rates, and how the information collected provided meaningful insight into events going on in their system–both how operational events and previously unknown activities at major customer locations were impacting the network.

The Miami-Dade Water and Sewer Department (MDWASD), the largest water utility in the southeastern United States, supplies potable water service to over 2.3 million customers in southern Florida. Water is distributed through a distribution network comprised of more than 5,300 miles of pipeline. MDWASD is constantly working to address the identification of pipeline renewal needs in new and innovative ways. MDWASD recently developed a plan to renew large amounts of the system pipeline network that uses a computerized, risk-based pipeline asset approach mixed with a set of engineering decision criteria to identify areas of this very large system to focus the work on. This paper provides a detailed description of the development of the pipeline renewal program leveraging MDWASD’s geographic information system (GIS) database. The approach utilized historic records of past pipeline breaks and failures as well as spatial analysis to rank each pipeline for its likelihood of failure. The consequences of failure were then calculated based on a number of factors such as the amount of system demand affected in a pipeline outage and the proximity to critical infrastructure, human activity, roadway traffic and commerce. The estimated likelihood of failure for each pipeline was then multiplied by the consequence of each pipeline failing to rank each segment within the 5,300 miles of the system. The scores were then applied to the MDWASD GIS for tracking and reference.

As a part of a larger force main condition assessment program, the City of Phoenix identified a need for a comprehensive force main air release/vacuum valve and isolation valve assessment program for those valves located within the City right of way. The City of Phoenix utilized an on-call with a local consulting firm, in conjunction with a local manufacture rep firm that specialized in air release valves and pipeline monitoring, to execute a sewer air valve assessment pilot on force mains located in the southeast part of the City. In addition to inspecting, cleaning, and assessing the force main air release valves, the project included efficiency monitoring at one of the lift stations to measure operational improvements resulting from conducting downstream valve adjustments or repairs/replacements. Historically, the primary focus for wastewater collection systems has been how to optimize the operation and efficiency of the pumps at lift stations. While that is a good approach for energy considerations at the lift station, the potential impact of the air release valve operation downstream from the lift stations can be overlooked. The air release valves downstream can greatly impact the pump efficiency, run times, and ability for the lift station to move flow through the force main. The purpose of this pilot was to accurately monitor and quantify the operation and efficiency of the lift station pumps before and after maintenance and/or replacement of air release valves in the force main system. In addition, the operation of the pumps was carefully evaluated to determine if there were any advantages to operating the pumps in an on off sequence vs. utilizing the variable frequency drives to control the pump speed and flows. Air in a force main system due to improperly operating air release valves can create surge events and increase pump run times, resulting in increased operating costs and reduced pump and force main useful life. The study sought to quantify the pump operational improvements and efficiencies after servicing and/or replacing the air release valves. There were a couple of challenges related to the monitoring and analysis aspect of the project. First, an initial operational base line was not established when the lift station was first started up and put into operation. Without this base line, although comparative conclusions can be drawn based on before and after valve maintenance/replacement, it is difficult to compare current operations to how the station originally operated new. Second, two air valves that are closest to the station, one inside the station, were not able to be assessed and evaluated as a part of this project. Although the valves appear to be newer than the valves that were evaluated in the vaults, they could still impact the operational efficiency of the force main following the servicing and replacement of the other valves downstream and in the vaults. This paper will discuss the implementation of the pilot study and highlight the operational and energy efficiencies that can be gained with a comprehensive air valve assessment and rehabilitation program.

Closed circuit television (CCTV) is the most employed technology in inspection of sewer pipelines by municipalities in North America. Generally, visual inspection of sewer pipelines is done manually by a certified operator which is time-consuming, costly, and error-prone due to the operator’s experience or fatigue. Automating the detection of anomalies can reduce time and cost of inspection while ensuring accuracy and quality of assessment. However, various types of defects in sewer pipelines and numerous patterns of each, make it difficult to detect the defects using computer vision techniques. This paper proposes an innovative and efficient anomaly detection algorithm to provide automated detection of sewer defects from data obtained from CCTV inspection videos. The algorithm employs Hidden Markov Model (HMM) for proportional data modeling. The algorithm performs real-time anomaly detection and localization and consists of modeling conditions considered as normal and detecting outliers to this model. The proposed model is tested on videos from sewer inspection report of the City of Laval, to evaluate its performance in anomaly detection in sewer CCTV videos.

Electromagnetic inspection followed by acoustic fiber optic (AFO) monitoring is a strategy used by many utilities to manage prestressed concrete cylinder pipe (PCCP) transmission mains. The electromagnetic inspection obtains a baseline condition of the prestressing wire wraps while the AFO monitoring detects each subsequent wire break. This data can be coupled with structural analyses for an up-to-date condition assessment of each section of pipe. However, translating the condition assessment to actionable information is not always straightforward. A number of factors, such as the rate of wire breaks, pipeline history, hydraulic concerns, criticality, consequence of failure, and other work being completed at the time all need to be considered. This paper highlights three unique case studies regarding AFO monitoring decisions for one utility. Each case study discusses an active PCCP that experiences a number of wire breaks, as detected by the AFO monitoring system, and the factors and elements that led to the subsequent decision to repair the pipe section or to continue to monitor. The paper shares lessons learned and experiences from engineers that are challenged with the task of managing PCCP on a daily basis.

An estimated 26.5 million m³ (≈ 20%) of treated water is lost through leakages from water distribution pipelines every day in the U.S., and this loss is expected to grow in the coming years as a result of deteriorating infrastructure. Over the past few years, there has been a strong research focus on developing and deploying permanent pipeline leakage monitoring systems that will detect and locate significant leakages in near real-time. While novel non-invasive, cyber-physical algorithms are emerging to enable continuous system-wide leakage monitoring, their life cycle cost are yet to be thoroughly investigated. In an attempt to address this knowledge gap, this paper presents a framework for estimating the life cycle costs of network-wide leakage monitoring systems, and demonstrates it using a benchmark water distribution system layout. This paper identifies the hardware and software needs of a surface vibration-based leak detection technique and elucidates its operational scheme that will impact the life cycle cost for reliable leakage monitoring of water distribution systems. The approach and the demonstration presented in this paper will inform how sustainable (i.e., cost wise) and feasible the studied leakage detection system is and as a whole, this paper will be informative to water utility owners.

With the increasing complexity of servicing water transmission mains and sanitary sewer force mains in urban areas, change is needed in how facilities are planned, designed, built, and maintained. This paper presents strategies for the control of external and internal corrosion/degradation of these facilities as part of a comprehensive Asset Management Program. Several strategies are available to operators, including: (1) run to failure, (2) run and repair as required until failure, or (3) operate using preventative maintenance to provide an indefinite life. The following are examples of these strategies: Operating a pipeline to total failure. Operating a pipeline until failure occurs and making point repairs as required. Operating a pipeline with preventative maintenance giving the pipeline an indefinite life span. In today’s water and wastewater industry, strategies 1 and 2 are most commonly employed. This paper examines how appropriate planning, design, building, and operation will facilitate indefinite usage of existing pipelines. Based on a review of hundreds of condition assessment evaluations of water transmission mains and sanitary sewer force mains throughout the western United States, and this presentation we present the case for a change on how water and wastewater conveyance systems are delivered to the market place.

The City of Columbus Department of Public Utilities (DPU) operates three water treatment facilities, including the Hap Cremean Water Plant (HCWP) and the Dublin Road Water Plant (DRWP). The HCWP and DRWP treat surface water with a variety of processes including lime softening. The waste lime slurry from this process is pumped to a waste quarry through a 17-mile long 12-inch diameter ductile iron (DI) force main for the HCWP and a three-mile-long 14-inch diameter DI force main for the DRWP. There have been some failures on the pipelines in the past, some due to corrosion impacts, which have resulted in lime slurry releases to waters of the State. Due to these releases, the Ohio EPA directed the City to take the proper actions to prevent further releases of lime slurry from the main. The City contracted with Brown and Caldwell to conduct an inspection of the pipelines to determine condition and to identify deteriorated sections. Brown and Caldwell proposed the use of the See Snake electromagnetic in-line inspection tool from PICA, Inc., a division of Russell NDE. Like most utility owners, the City is wary of inserting tools into pipelines that may already be weakened by corrosion. Brown and Caldwell and PICA have developed a three-phase program to introduce the inspection technology to the City and to carefully manage the risks to the pipeline. The first phase in the program is the inspection of a similar sized water main. A 1,700 foot segment of 12-inch DIP water main was selected due to its ease of access and potential for minimal disruption to service. With the confidence developed from a successful inspection in Phase One, a second pilot phase would be initiated to perform an in-line inspection on a selected segment of the lime slurry line. The goal of Phase Two was to prove that the approach is feasible in the slurry system and to further build confidence in the technology and approach. Phase Three would entail the inspection of the remainder of the pipeline. The paper will describe the planning that went into the preparation for the inspections, the results of the inspections, and a discussion of the lessons learned.

York Region (the Region) is one of the fastest growing communities in the Greater Toronto Area. It operates a “two tier” level of government, taking responsibility for the large diameter trunk water mains and sewers serving the population. The lower tier municipalities take responsibility for local distribution and collection systems. The Region owns and operates approximately 350 km of large diameter watermains which transport water from treatment facilities to the local distribution system. The pipe material inventory is predominantly concrete pressure pipe (AWWA C301) at 83%, with the next largest material group being ductile iron (DI) at 9% and PVC & HDPE make up 7% of the inventory. The system is relatively young in age, with 72% of its entire inventory being less than 20 years of age, and 27% being 20 to 40 years of age. The diameter of the Region’s watermain inventory ranges from 1800 to 400 mm with an average diameter of approximately 750 mm. After early adoption of field investigations of concrete pressure pipes using leading edge condition assessment technologies including wet, live deployed electromagnetic inspection technologies along with confirmatory forensic exhumations, the Region took a step back to evaluate the effectiveness of its tactic and subsequently determined to take a more strategic, risk-based and holistic approach to its watermain asset management. The Region also collaborated with other municipalities in North America to identify industry best practices. A gap analysis was then undertaken to identify a road map of actions and timeframes to better target future condition assessment activities. It was determined that a few key exercises are best to be completed in advance of field works. As a summary those tasks include: sorting watermain in descending priority sequence according to risk, to think through the potential results of condition assessment and subsequent resulting actions in advance of the field works and to better plan and prepare for contingencies and probable outcomes. By better understanding the inspection and condition assessment tools and their suitable uses and likely results, the Region has a clearer and more fulsome understanding of how to manage risk while sustaining this critical infrastructure at the lowest overall lifecycle cost.

Understanding the current condition and deterioration mechanism of sewer pipe networks is a critical step in improving national wastewater systems. Several studies have attempted to develop deterioration models for sewer pipes, and a common concern raised by those studies was data quality. Due to quality issues in current data collection practices, approximately one-third of the data are not usable for asset management purposes. Those data primarily are related to pipes that are in deficient conditions and when the inspection process is interrupted by severe defects in the pipes. The objective of this paper is to present a quality assurance process for the Pipeline Assessment and Certification Program (PACP) inspection data which may be used to develop a unified and useful database for further analysis. PACP is a widely accepted standard data collection format for closed-circuit television (CCTV) inspections of sewer pipes. PACP databases with more than 90,000 inspections provided by four municipalities across the nation were examined to identify common data quality problems. The proposed quality assurance process consists of three steps: (1) Formulating a quality assurance framework; (2) Detecting problematic data; and (3) Resolving problematic data. The results show that, by applying the proposed quality assurance process, the percentage of good quality inspection data increased from 50%–75% (pre-process) to 95% (post-process). This paper contributes to the overall body of knowledge by providing a robust data quality assurance process for underground sewer pipe inspection data, which will result in quality data for sewer asset management endeavors.

The challenges of managing buried water infrastructure has been well documented via numerous outlets, including AWWA, ASCE and the EPA. As infrastructure continues to age, with pipelines reaching and exceeding their design life, utility owners face significant challenges in providing reliable service to their customers. Despite the operational and financial challenges facing utilities today in managing their buried infrastructure, Howard County, MD, has successfully stayed at the forefront of the industry for innovative and responsible approaches to pipeline management. This proactive philosophy led them to initiate a multi-phase study to determine the condition of water mains within one of their oldest residential areas, the Village of Wilde Lake, where the pipelines date back to 1967. The County was seeking to maximize the life of the water mains, while also minimizing the financial and logistical impacts to the community while continuing to maintain a high level of service. During Phase I of the study, a countywide risk assessment strategy was established to prioritize and plan subsequent condition assessment and renewal activities for 88,000 feet of cast iron and ductile iron pipe ranging in size from 6 to 12-inches in diameter. The data collected during these assessments was used to establish a renewal and management strategy for the area. Trenchless renewal for large diameter water mains has been used for decades; however, there are several emerging technologies for renewal of distribution mains that have proven to be an effective alternative to full replacement. Given that more than 90% of their 1,000 miles of buried water pipes are distribution mains, the County was eager to pilot some of these techniques, as full replacement of their aging distribution mains would come at a significant cost and disruption to the community. As part of Phase 2, several rehabilitation technologies were evaluated, including CIPP, pipe bursting, sliplining, spray-on lining, CFRP repairs, and internal repair sleeves. Ultimately, two technologies were selected for piloting (CIPP and pipe bursting) on the distribution mains and successfully implemented as part of Phase 3. This paper will cover the County’s emerging holistic 3-phase approach to managing their distribution mains, including the prioritization and condition assessment phase, renewal evaluation phase and rehabilitation implementation for an area representative of their full distribution system, with a focus on the emerging renewal technology selection.

Corrosion and pitting defects in ductile iron pipes (DI) reduce the structural strength of the pipe. There is no clear explanation rehabilitation option regarding the severity of damage. There are different opinions regarding the appropriate level of repair. Lining options include non-structural corrosion barriers (Class I), semi-structural repairs capable of spanning some holes and gaps (Class II and III) and fully structural repair able to withstand all loads (Class IV). Selection of the appropriate rehabilitation method is critical for overall performance of the pipeline. Failure of a proposed repair method could be problematic due to the social, political, and environmental impacts of the failure. To facilitate better decision making regarding the most appropriate repair method and to address the risk associated with the failure, appropriate testing and quality control need to be implemented. In addition, for planning and capital budgeting, it is important to determine the additional strengthening of the repair method on the deteriorated section and its risk of failure. In this paper, a structural evaluation of damaged 12-in., 24-in., and 36-in. DI pipes will be discussed considering external corrosion of the pipe (the most common failure mode of DI pipe). This paper provides a clear and concise picture of how to determine the appropriate repair method of damaged DI pipelines by considering different pipe and soil interaction. This paper will help the pipeline owner determine which repair method needs to be selected for the specific condition of their pipeline.

The City of Wichita, Kansas Utilities Department, supplies and distributes water, and collects and treats wastewater for the city’s residents. In late January 2015, City of Wichita officials discovered a water leak in its primary 66-in. water line that conveys combined raw water supplies. Through quick engagement with a number of consultants and contractors, the team was able to construct a permanent bypass, determine the source and cause of the leak, and repair the leak in less than a month. After identifying the location of the leak, the team evaluated various internal and external solutions to fix the pipe promptly and return the line to service prior to the upcoming irrigation season. The substantial challenge with correcting the pipe externally was that the leak was located under the meter building and adjacent to the 84-in. effluent line. These obstacles, in addition to the need to maintain a quick repair schedule, resulted in an internal solution that involved installing carbon fiber-reinforced polymer (CFRP) and a joint seal at the aging downstream joint for added protection and extended life of the pipe. Repairing this critical infrastructure to full operation in a rapid manner avoided any further obstacles such as water conservation mandates or boil orders, and restored customer faith in the safety of their water.

This paper examines a case study illustrating the approach used by the City of St. Joseph, Missouri, to evaluate the condition and extend the useful life of a 12 to 17 foot diameter concrete and brick combined sewer. The case study includes a description of the methodology used to collect data on the condition of the pipeline, an evaluation of methods to address the defects identified and an explanation of how funding is an important part of the project.

The City of Columbus, Division of Sewerage and Drainage (DOSD), is carrying out a long-term condition assessment and rehabilitation program for its large diameter sewers (sanitary, combined, and stormwater). As a part of this program, American Structurepoint, Inc. (ASI) team was retained by the City to conduct condition assessment for the large diameter sewers in the downtown Columbus area. The project scope includes inspection and condition assessment of approximately 45,000 LF of sanitary, combined, and storm sewers with diameters ranging from 36 to 180 inches (from 900 mm to 4.6 m) and approximately 260 manholes.

Denver Water’s Vasquez-St. Louis Siphon 1 facility is a 72-in. diameter steel inverted siphon installed in 1935. A segment of pipe was modified in 1982 so that it could be installed in a large concrete vault supported on a series of saddle supports. After modifications were completed, the pipe slowly yielded both circumferentially and longitudinally. Deformation occurred at the saddle horns at one support and longitudinal compression occurred on the underside of the pipe. A metallurgical failure analysis was undertaken to further understand the potential contributing causes of the failure. A chemical composition test was performed to determine the steel’s carbon content and the presence of impurities. Microstructure testing determined the phase of the steel lattice, the material grain size, morphology, and the predominance of intermetallic inclusions formed due to impurities. Microhardness and tensile testing quantified the materials resistance to plastic deformation and verified that strain hardening had occurred. This paper presents results of the failure analysis and lessons learned. Denver Water will utilize the results as an asset management tool for similar facilities that were installed in the same time period.

King County, WA, recently completed a condition assessment of two parallel 30-in. diameter steel force mains that were constructed in 1998 after a pipeline failure was observed early in the pipeline’s service life. The condition assessment revealed internal corrosion. The epoxy lined, cement mortar coated pipes are approximately 25,000 lineal feet long and have a steel cylinder thickness of 0.14 in. This paper describes the methods selected for assessing the thin walled steel pipes, the assessment conducted, and conclusions drawn from the information collected. The assessment included construction of access points as no access was provided with the original installation. Assessment methods included external investigations (soil corrosivity, close interval potential survey, and direct assessment) and internal investigations (CCTV inspection and ultrasonic wall thickness measurements). The condition assessment concluded that although most of the joints have some corrosion and there are many locations of liner failure and pitting, the corrosion visible in CCTV video is mostly on the steel surface. Localized external corrosion was observed but the rate of corrosion is slow. Wall thickness measurements at points of corrosion indicate the remaining wall is adequate for continued operation at current operating conditions. Recommendations included spot repair of the lining, installation of passive cathodic protection for long welded sections, and periodic inspection to determine the probable rate of corrosion in order to plan for future service.

Growing urban landscapes, changing climatic patterns, devastating floods, detrimental pollutant discharges, coupled with aging stormwater infrastructure have multiplied the complexity of managing stormwater. Conventionally, stormwater was managed through gray infrastructure–networks of linear engineered structures. Recently, many cities across the U.S. have embraced the emerging concept of green infrastructure; to use land as a natural drainage system. Though the adoption and implementation of green infrastructure will not solely solve this issue, it will supplement and reduce the burden on the existing gray infrastructure. Therefore, specific attention to issues regarding gray infrastructure is of prime importance, as its performance will have a significant influence on the effectiveness of the stormwater system as a whole. This paper will synthesize the stormwater industry practices and provide guidelines for the following areas; inspection technologies, condition rating systems, risk assessment and prioritization, and renewal engineering techniques through case studies. These case studies were developed with inputs from the participating utilities; geographically spread across the U.S. EPA regions. Participating utilities are Sanitary District 1, KY; City of San Diego, CA; Gwinnett County, GA; Virginia Beach, VA; City of Chesapeake, VA; City of Shawnee, KS; City of Shoreline, WA; and City of Bellevue, WA. To summarize, this paper will act as a knowledge base on how to manage stormwater pipe infrastructure assets.

When planning a pipeline replacement program, drinking water companies are faced with a dilemma. On the one hand, factual information about the condition of the water mains will lead to better decisions about which mains to replace, which in turn leads to long-term capital efficiency gains. On the other hand, gathering this information is costly, and only provides financial value when the information leads to a better decision being made. Performing a cost-benefit analysis of the case for data gathering is also difficult, as the benefits are difficult to project. This paper investigates the relationship between the amount of information collected on the condition of water mains and the quality of replacement/rehabilitation decisions made on those mains. A mathematical model based on quantifying the financial risk associated with decision making errors is introduced. This model predicts the financial benefits of information collection programs, as a function of the amount of condition information gathered. An economic optimization equation using the model is presented. This equation yields the Economic Assessment Level: the amount of condition information needed to minimize the total combined spending on information gathering and incorrect decisions. Case studies and examples of the impact of different levels of information gathering are presented. The results of these programs are compared with the predictions of the model, illustrating how the calculations can be used to improve capital improvement program efficiency real world situations.

Home to over 2.4 million people, Metro Vancouver is responsible for delivering a variety of services and policy leadership for its members, which comprise 21 municipalities, one electoral area and one treaty First Nation. Among these services is the provision of potable (drinking) water. Operated by Metro Vancouver, the Capilano Raw Water Pumping Station in North Vancouver, British Columbia, is one of the largest municipal water pumping stations in North America with eight 2,000-Hp pumps and a capacity of 285 MGD (1,080 ML/d). This facility helps to ensure a reliable and safe supply to one of the largest cities in Canada. In support of commissioning the pumping station, a comprehensive transient analysis was carried out to mitigate potentially damaging water hammer conditions. As part of the transient analysis, a detailed field testing program was developed and conducted to confirm model results and evaluate the effectiveness of the surge mitigation measures. The field testing plan identified preferred data logger locations for the tests and identified additional information needed from the computerized data acquisition and control systems. A series of hydraulic transient field tests were performed over a period of three days. Field data results were then compared to model results for validation of the model. This paper will review: the development of the field testing plan; the decision making process for the placement of high speed pressure data loggers; level of coordination needed to complete the field tests; and a comparison of model versus field results.

The City of Phoenix began municipal water utility operations in 1907. Today, the Phoenix Water Services Department treats and distributes tap water to 1.5 million customers daily, and handles wastewater operations for 2.5 million residents in the Valley of the Sun. Our vast infrastructure includes 7,000 mi of water lines and 5,000 mi of sewer lines, eight treatment plants, 50,000 fire hydrants and 95,000 manholes over a 540 square-mile service area. Managing the U.S.’s sixth largest city’s water utilities is a unique challenge; Phoenix is a young city with old infrastructure. The oldest known water mains in Phoenix’s system date back to the early 1900s. The industry standard range for water pipe life expectancy is 50 to 100 years, but life expectancy depends on environmental conditions, pipe material and other factors, including the scorching summer heat, monsoons and occasional bouts of freezing weather. On the sewer side, Phoenix has pipes that are over 100 years old. This system is almost exclusively made up of vitrified clay pipe (VCP). Similar to the water system, the environment and monsoon-like weather can cause premature wear and tear. This paper describes the Phoenix Water Services Department water and sewer main assessment and rehabilitation programs from their inception in the early 1990s to today.

This paper presents the City of Ottawa’s recent experiences developing and implementing a condition assessment program for large-diameter watermains. A significant portion of the inventory is comprised of prestressed concrete cylinder pipe (PCCP) lines, and due to recent failures on these pipes, efforts have been focused on understanding the condition and failure mechanisms of the PCCP in their system. As the City has embarked on their inspection program, it has become apparent that compiling and managing available data, filling in missing critical pieces of data, selecting appropriate PCCP inspection tools, and interpreting inspection results are all critical to developing a complete program. The goal of the City’s condition assessment program is to identify distressed pipes with broken prestressing wires, evaluate the risk of failure of such distressed pipes, and repair or replace pipes at high risk of failure. In order to achieve this goal, the City needs to understand the structural capacity of the pipes, the sensitivity of the pipes to prestressing wire breaks, and which inspection technologies provide sufficient resolution in the distress estimation. This paper will present an overview of the original condition assessment approach at the City of Ottawa, data sources and gathering efforts, how the program evolved as well as the lessons learned and improvements of the program over time.

The new AWWA Standard C305 governs the renewal and strengthening of distressed prestressed concrete cylinder pipe (PCCP) by installation of carbon fiber reinforced polymer (CFRP) laminate liner. The standard provides material, design, and installation provisions for the CFRP liner of a distressed PCCP with a goal of providing a service life of 50 yrs even when the host PCCP continues to degrade. The CFRP liner is much more flexible than the PCCP and is designed to provide the strength needed when subjected to the load combinations that are used for the design of the host pipe (1) at the time of installation of the liner, (2) when the host pipe has fully degraded and the liner is reduced to a flexible pipe, and (3) at all intermediate stages of distress. In this paper, failure modes and design limit states of a CFRP liner are identified, the governing design formulas are presented, and the theoretical and experimental basis of each are presented. The designs that conform to this standard are expected to provide strength, durability, reliability, time effects, and watertightness. Moreover, we must achieve these goals through a design that does not compromise its economical competiveness. Strength is governed by laminate stresses and by liner stability consideration and requires identification of all loads and load combinations, calculation of load effects, and determination of the liner resistance for each failure mode. Durability requires identifying and accounting for material adjustment factors that account for loss of strength during the service life of the structure resulting from exposure to the environment. Reliability is ensured through load and resistance factors that account for the variability of loads and of resistance. The effect of load duration on the strength and modulus is included as a time effect factor that is calculated from regression analysis of time to failure test of laminate specimens subjected to different sustained stress levels. Watertightness is achieved through successfully testing the laminate or a part of the laminate lay-up sequence in a pressure chamber with a window simulating loss of prestressing over a band.

The City of Phoenix (City) has been an industry leader in transmission main assessment and renewal since the early 2000s. The City operates a water system which includes nearly 7,000 mi of mains and serves nearly 1.5 million customers over more than 500 square miles. The City’s approximately 600 mi of transmission mains range in diameter from 16 to 108-in. Responding to worldwide failures of prestressed concrete cylinder pipe (PCCP), the City began its transmission main program with a focus on assessing all 150 mi of PCCP in its system. The City has now assessed more than half of its PCCP and has an established program in place to complete assessment of all PCCP by 2027. The City’s PCCP assessment program initially focused on mains constructed in the 1970s, when relaxed PCCP standards resulted in pipe that is more susceptible to environmental and operational damage. Data collected over 75 mi of PCCP assessment shows that the City accomplished its goal of focusing first on the most at-risk pipe and that the overall damage profile of City PCCP as a function of installation year correlates well to national averages. The program has improved the operational resiliency of the City’s transmission mains by documenting how to isolate and dewater mains for inspection and how to move water to compensate for mains out-of-service for inspection. Effective mitigating actions and risk-management strategies have emerged which can be applied in future transmission main assessments. For PCCP, the City identifies pipe in need of operational modifications or renewal through a combination of internal inspection techniques and technologies. The worst mains in the City’s system have been identified for renewal using steel sliplining or replacement. The City has completed nearly 10 mi of steel sliplining and approximately 3,000 ft of PCCP replacement as a result of its program. Operational modifications have been identified as an important strategy to reduce risk of pipeline failure. PCCP condition data collected in Phoenix shows a clear link between transients, operating-to-design pressure ratio, and pipe damage. The City has implemented a system-wide pressure and transient monitoring program focused on eliminating surges and reducing pressure in at-risk PCCP. As the City’s PCCP program has become established, the City has expanded its focus to additional transmission mains with a multi-year transmission main program focused on assessment of more than 200 mi of bar-wrapped pipe beginning in 2017. This paper focuses on the evolution of the City’s PCCP management program from 2003 to the present.

Although pipeline systems are the most economical and safest way of oil and gas transportation, there have been an increasing number of incidents. Therefore, pipeline operators need to constantly evaluate and update their preventive maintenance (PM) strategies. This paper performed economic analysis of PM strategies based on the cost of internal and external corrosion-related failures and developed optimal PM mathematical cost and time models for natural gas pipelines. The data used for this study was collected from eleven largest natural gas transmission pipelines. This study developed a method to calculate the optimal replacement time for potential failures based on the ratio of preventive replacement cost to corrective replacement cost. Moreover, this study developed a model to calculate cost of PM strategies based on the optimal replacement time. The results of this study helps decision-makers in the oil and gas industry to select the proper PM strategies for corrosion-related failures.

Life cycle management of pre-stressed concrete cylinder pipe (PCCP) presents unique challenges for water utilities, given concerns for catastrophic failures. New Jersey American Water experienced a significant rupture on a 48” diameter PCCP pipeline in 2012. The utility’s team began evaluating available PCCP test methodologies in 2013 to accelerate their knowledge of condition of the 172+ miles of PCCP in their network. Acoustic wave propagation (AWP) testing was investigated given its ability to quickly test large amounts of pipeline, minimize water supply interruptions, and reduce customer disturbances. AWP survey-level testing can be used to identify concrete pipeline segments with reduced structural stiffness. Reduced pipe wall stiffness in concrete mains may be an indicator of broken prestressing wires, lower prestress, deteriorated mortar coating, cracked concrete core, and other issues. The presentation describes AWP stiffness testing in PCCP mains, and the structural and failure risk analyses (and external pipe inspection results) used to evaluate the predicted pipe stiffness. Test results are evaluated based on variability of the effective (measured) pipe stiffness within a given pipe class, and comparison of the measured versus nominal (calculated) pipe stiffness. The presentation will also include an overview of New Jersey American Water’s tiered approach to pipe condition assessment, and a case study focused on a critical 60” PCCP main.

The goal of a pipeline condition assessment program is to identify individual distressed pipe pieces or distressed sections of the pipeline that have high risk of failure and to repair such pipes in order to maintain pipeline reliability at a desired level. Implementation of a pipeline condition assessment program requires prioritization of all pipelines in the system to determine which pipelines to focus on first, selection of appropriate inspection technologies, implementation of inspection technologies, and interpretation of the inspection results. The purpose of this paper is to present a desktop model for prioritizing pipelines for inspection based on their criticality, failure risk curves for evaluating sensitivity to wire breaks for PCCP for the purposes of selecting appropriate inspection technologies, and field inspections for validating and refining the desktop model.

The Indian Bend Wash is a drainage channel in Scottsdale and Tempe that provides flood protection for residents and businesses. As the wash approaches the Salt River (Tempe Town Lake), levees provide protection from the higher flows that would typically flow out of the banks in this area. The levee design incorporates pipelines, or side inlets, to safely convey impounded storm flows on the landward side of the embankment into the wash. These side inlets pose a potential threat to the structural integrity of the levees. The U.S. Army Corps of Engineers (Corps) periodically inspects structures in the rehabilitation program (RP) to ensure continued flooding protection. A periodic inspection report (PIR) is created to document the results of the inspection. Project Engineering Consultants, Ltd., (PEC) provided a condition assessment of twelve side inlet pipes in the City of Tempe (Tempe) portion of the levee system under the direction of Tempe and the Flood Control District of Maricopa County (FCDMC). The Corps recently adopted the National Association of Sewer Service Companies (NASSCO) standard for assessment of pipes and culverts that penetrate the levees. PEC relied on the NASSCO Pipe Assessment Certification Program (PACP) to provide the side inlet pipe assessment. The PACP assessment, the first to be implemented on these levee pipes, identified potential issues and provides a baseline condition rating for the side inlet pipes. Using this baseline, future assessments will indicate the rate of change in pipe deterioration and estimate the remaining useful life of the facility. This paper presents several aspects of the NASSCO PACP procedures for the levee side inlet assessment. The discussion will include methods employed to overcome the challenges not typical in sanitary or storm sewer systems during pipeline assessments. The pipeline assessment produces large amounts of data during the inspection and assessment process, which categorizes and summarizes the data for ease of use. This data includes information that helps develop structural, operational, and maintenance defect ratings for each segment of the side inlet. The narrative discusses the ratings and other observations, including the interpretation and summary of the assessment results. An organized reporting table was also developed to succinctly present the results of the assessment to the agencies for a response to the inspection findings noted in the PIR.

Failures of large diameter pipes can cause significant social, environmental and economic impacts. The actual failure mechanisms of buried pipes are difficult to isolate because many external and internal factors are commonly involved. Moreover, the major pipe breaks occur below the ground and the root cause of failure may be masked by the violent nature of the break. Detailed investigations were undertaken to examine and understand the failure mechanisms of buried large diameter cast iron water pipe breaks. We used various approaches to gathering field evidence from failed as well as unfailed pipes, numerical simulations, field instrumentation and full-scale laboratory pipe burst testing. Large diameter pipes tend to fail predominantly by longitudinal fracture. The failure mechanisms involving longitudinal fractures indicated that a large corrosion patch in the pipe barrel is commonly needed for pipe failure. This finding is in contrast to the belief that small pits are mostly responsible for failures. This means that many of the current condition assessment techniques currently targeting the detection of pits in pipes need to focus on the detection of larger patches of corrosion. The research also found that pipes fail by developing a crack first within a corrosion patch that could lead to water leakage until the crack grows sufficiently long to cause a major break. This concept is referred to as “leak before break” (LBB) for cast iron pipes. This concept can potentially be used for failure prevention of critical pipelines through improved leak detection.

The Olmsted Hydroelectric Power Plant was originally constructed in 1904 at the mouth of Provo Canyon in Utah, and has been in operation for over 100 years. The power plant is a key feature of the Central Utah Project and continuing the operation of the power plant and upstream penstocks is critical to maintaining the 429 cfs water right associated with the power plant that allows the Central Utah Water Conservancy District (District) to deliver water to customers located along the Wasatch Front. The power plant and penstocks have operated well beyond their useful life expectancy. In an effort to determine the most efficient future operation and management of the facility, the District completed a comprehensive condition assessment of the existing power plant and upstream conveyance system including: three 48-in. diameter and one 72-in. diameter riveted steel penstocks, a hydraulic regulating structure (pressure box) that provides approximately 325 ft of head for the power plant, a 900 foot long non-pressurized limestone rock tunnel, approximately 1,700 ft of existing 102-in. diameter concrete encased steel pipe, and an overflow cliff spillway structure. This paper summarizes the condition assessment and presents the recommendations for replacing the existing penstocks, pressurizing the existing rock tunnel, modifying the cliff spillway structure, and the hydraulic and surge considerations related to operation of the hydroelectric power plant. Since the Olmsted Power Plant was constructed in the early 1900s and design or as built drawings were not available, the evaluation included a three dimensional (3D) light detection and ranging (LiDAR) survey of the interior and exterior of the hydraulic structures, rock tunnel, and cliff spillway structure. The condition assessment evaluation resulted in a recommendation to replace the existing power house and penstocks with a new hydroelectric power plant and a new 84-in. diameter steel penstock. The pressure box was removed, the overflow elevation of the cliff spillway structure was increased, and the system was transitioned to downstream flow control at the power house to eliminate the unbalanced flow operation of the existing system. This paper provides a detailed discussion of key issues and project challenges associated with the rehabilitation and replacement of a historical power plant from the viewpoint of the Owner and the Engineer.

This paper examines the benefits and applications of performing a cable-less multi-sensor measurement survey. Video recordings prove that the battery powered and ballasted Pipe-Inspector remains neutrally buoyant and remains stable while centrally positioned inside the pipe, eliminating spiralling or bouncing data collection inaccuracies. Advancements enabling pinpointing leaks from within the pipe to a distance and clock position are enabling system owners to better understand their pipe’s integrity and risks. CCTV adds a level of understanding to better manage the system’s health, when correlated to pressure and leak survey findings. The cable-less function enables very long lengths of pipe to be surveyed with no impact to surface urban or environmental conditions. This technology advancement is proving financially beneficial to system owners concerned with limited budgets. First line triage of a pipe’s condition is now capable of simultaneously providing many valuable sources of information to better assist engineering decisions for condition assessments.

For a large-scale, multi-phase cable installation located in central Maryland, HDD has been used to install new duct bundles to reduce surface disturbance associated with open-cut construction. Complex geologic conditions and excessive downhole pressures have caused significant fracouts (inadvertent returns) during previous project phases, resulting in excessive cleanup costs and permitting delays. To reduce this risk, the project team has implemented a comprehensive instrumentation program for 15 new HDD bores. This includes instrumenting the pilot rods, and reamers. The instrumentation allows the project team to monitor rate of penetration, pump rates, tool torque, and downhole pressures during all aspects of drilling, including pilot hole development, reaming, and duct bundle pullback. Data collected is provided in real-time to all team members using wireless links for immediate evaluation. The instrumentation, coupled with a site-specific drill fluid design, has allowed immediate response to elevated annular pressures, significantly reducing the incidence rate of fracouts. The data collected also allows evaluation of the contractor’s activities, from the standpoint of drilling efficiency. This paper provides a summary of the HDD installations, the instrumentation used, and the benefits and lessons-learned from real-time downhole data acquisition.

ALCOSAN provides regional wastewater conveyance and treatment for 83 municipalities in Alleghany County, PA. They own and operate approximately 90 mi of interceptor sewers and the 250 million gallon per day Woods Run Wastewater Treatment Plant. There are over 4,000 mi. of combined and separated collection sewers located within the ALCOSAN service area owned by the municipalities. Utilizing EPA’s Integrated Watershed Approach, large portions of the collection system are being regionalized to facilitate the development of a more efficient and equitable upgrading and long term operating model. Integrating data from such a diverse array of sources is a very challenging task. Maintaining a high quality data capture with such an immense condition assessment data set is both a challenge and essential component of fully understanding the technical and financial ramifications of the condition assessment process accurately and expeditiously. The condition assessment program in support of regionalization is a traditional CCTV data capture with defect characterization of the conveyance infrastructure and its appurtenances being carried out with NASSCO’s PACP and MACP data logging techniques. The data capture with PACP/MACP involves the recording of literally millions of observations and requires considerable innovation to process the data efficiently and in a consistent manner such that clarity of risk and upgrading priorities is maintained. A traditional WRc/ASCE MOP 62 Risk Model was initially developed to lay the foundation for establishing condition assessment priorities, intervention timing, and policy. The model used readily available surrogate data to develop overall cost factors (an indication of the direct and indirect cost of collapse without rehabilitation intervention) for each reach of sewer pipe with the entire conveyance system. To facilitate a consistent and common approach to condition assessment and rehabilitation rationalization amongst a diverse pool of reviewers and end stakeholders; the writers mapped out the desired roadmap from defect patterns to rehabilitation assignment in some detail with the aid of master algorithms that analyze the specific pattern of defects in each MH-to-MH reach to suggest an optimum rehabilitation work stream and work limits in the reach. While trained practitioners can modify the rehabilitation assignment in quality assurance (QA) review, the master algorithms have been very successful in attaining a consistent approach in rehabilitation assignment between reviewers and promote a transparency in policy to all stakeholders that is well aligned with best practice in rehabilitation selection. By attaching a cost estimating model to the defect database and integrating it with the prioritization model and intervention policy; the Owner is able to have an initial understanding of the financial ramifications of the defects, the nature of upgrading programs that are required and the optimum timing associated with the program; instantaneously upon QA of the condition data which is typically long before final QA reviews of the rehabilitation assignments. The paper provides an overview of the development of the risk model and of the innovative approaches utilized in rehabilitation rationalization from the Pilot Regionalization program that was carried out in 2015 and 2016.

Transportation agencies often allow metal pipes as an option for cross drains under/along roads and highways. Metal culverts can corrode over time at various rates based on their environmental conditions (e.g., corrosive nature of coastal soils, high water table and saltwater intrusion). This paper focuses on applying readily available soil data such as spatial distribution of soil types and soil characteristics (e.g., pH and conductivity) towards creating a geospatial information system (GIS) based approach to identifying corrosion zones in the coastal regions. A combination of data, obtained from field surveys provided by the Louisiana Transportation Research Center and Web Soil Survey Data provided by Natural Resources Conservation Service, were used to create an interpolated surface representing zones corrosive to metal culverts. The role of the soil characteristics was incorporated in to the previously established corrosion models in identifying zones that will cause corrosion causing conditions for metal pipes.