Pipelines 2024: Planning and Design

Four leaks occurred within 3 months during the summer of 2017 within 235 ft of an 80-year-old, 40-in. welded steel suction line feeding the historic Fletcher Pump Station (PS). The suction line was described as significantly deteriorated when observed during the leak repairs, propelling its replacement up the LADWP priority list. The design to replace the existing line with a 48-in. welded steel pipeline became a top priority, with construction scheduled for the following year. Finding a corridor on short notice was challenging, and traditional design, fabrication, and installation methods had to be adjusted to fit within the aggressive schedule. LADWP designed pipeline lay-sheets in-house, started the pipe procurement before completing design, and coordinated with local impacted businesses within the year. Without time to relocate the congested substructures within the street, the design team devised a creative alignment within the sidewalk and nearby properties. With the Fletcher PS unable to be shutdown longer than 2 months, removing and replacing in place the entire existing suction line were not an option.

Portland, Oregon, is located in the heart of the Cascadia Subduction Zone and is expected to experience devastating impacts after an earthquake along this fault. In an effort to mitigate the impacts and improve system resiliency, the Portland Water Bureau needs a seismically resilient water pipeline across the Willamette River, as all of the six existing crossing are expected to be severely damaged due to liquefaction and strength loss of the loose riverbank soils. The proposed crossing is located in the Portland downtown core, which is a complex place with a wide array of existing utilities, multiple property owners, transportation corridors, and highly variable geology. This complex location requires design and construction methods to accommodate all the project constraints. Key to managing these constraints is using an appropriate trenchless construction technology. This Design–Build project evaluated multiple trenchless technologies, including horizontal directional drilling, microtunneling, and direct steerable pipe thrusting to install the more than 4,000 ft of 48-in. diameter welded steel pipeline needed for the project. Several unique shaft and pit configurations were needed to accommodate these various trenchless installations in a complicated urban area. This paper focuses on several design and construction method challenges unique to this project and the trenchless industry. Key among these challenges was determining how to accommodate up to 20 ft of lateral spreading of the riverbank ground surface, where a 36-ft diameter shaft will be sunk to accommodate a connection between two trenchless alignments. This paper discusses the comprehensive geotechnical design and analysis efforts to study the anticipated soil loading to the pipe and resulting pipe strains modeled using FLAC and ABAQUS computer software. These analyses were used to demonstrate pipeline performance at varying depths using different pipe wall thicknesses, steel pipe yield strengths, and cased/uncased pipe sections.

Design–Build projects clearly layout an understanding of all stakeholders on the location, quantity, and costs of the utilities to be relocated or constructed. So how do we take multiple funding stakeholders with competing interest to agree on cost, schedule, and scope? (The Three Pillars of Project Management). Using the Transportation Association of Canada (TAC) Guidelines to Utility Coordination on Public–Private Partnership Projects, we will discuss the planning and implementation of several projects recently planned in Ontario, Canada. The preparation of Request for Proposal (RFP) documents that allows for implementation of project goals, attaining stakeholder needs, and providing Project CO with the flexibility to still provide innovation is the difficulty put on the Engineers to maintain the balance of the competing interests. The intent of this presentation is to show the implementation of best practices through the use of Guidelines and the real-world consequences of their implementations. It will discuss and show the challenges with the implementation of the Public–Private Partnership (P3) environment into the existing processes. The issues with existing processes for stakeholders who do not understand how to implement their existing processes into the P3 environment and how to achieve their goals with their specific situation. The presentation will focus on the implementation of the TAC Guidelines to Utility Relocations flow chart and the challenges and lessons learned at each step using the Hurontario LRT as the project in focus. This will cover major components of the RFP preparation, including Planning, RFP preparation, and In-Market period. By having two different projects with two different fundamental approaches to utility relocation, the discussion will focus on the Bid phase implementation and negotiations with the stakeholders during the RFP preparation as well as the Detailed Design and Construction Phase.

The Buffalo Pound Non-Potable Water Supply System (BPNPWSS)–Regina Regional will supply non-potable water from Buffalo Pound Lake to industrial customers around Regina. The Regina Regional System is an extension of the existing BPNPWSS–East that currently supplies non-potable water to industrial customers in the Belle Plaine corridor. The planning of the pipeline began with utilizing GIS to show existing constraints. Once the route was chosen, hydraulic analysis was completed to determine the required pressure rating and diameter of the pipe to deliver the required water to the end users. The design of the pipeline took a unique and alternative delivery approach. The design of the pipeline was completed to 80% without a specified pipe type for procurement. A Request for Supplier Qualifications (RFSQ) pre-qualified three contractors to submit a proposal to complete the work. The proposals included the contractor’s proposed pipeline material for each section meeting the specified criteria, work plan and schedule, additional details on their previous experience, and their proposal price. Once the pipe types were chosen, the design was completed with the selected contractor’s input and construction began in May 2023. This paper will provide an overview of the planning and design process determining the pipeline route utilizing GIS, to 80% design of the pipeline, and finally to obtaining a qualified contractor and completing the design and construction. We will also discuss the challenges and benefits that this approach brought on.

In March 2022, an inspection of a 1950s 20-in. cast iron main was completed using ultrasonic thickness testing technology. In June 2023, a pipe segment on the inspected portion of the 1950s cast iron main catastrophically failed. No wall loss was identified in the first analysis of the failed pipe segment. A re-analysis of the data from the March 2022 inspection indicated that approximately 15 atypical signals were present on the failed pipe segment. Further investigations of the failed pipe segment revealed suspected graphitic corrosion present at each of the atypical signals that were available for closer inspection. Re-analysis of the entire pipeline showed an increase from 13.5% to 40% of pipe segments with wall loss or suspected graphitic corrosion. This paper will discuss the failure, the re-analysis, and investigations on the cast iron main, focusing on the atypical signals and WaterOne’s steps taken to manage the pipeline.

With population growth, expansion of industrial demands, and the challenges of installing high voltage (HV) and extra high voltage (EHV) cables in dense urban and other locations, structures such as tunnels and bridges for multi-purpose use are becoming attractive options. They offer the potential for reduced overall costs, environmental advantages, and less disruption to the community during the installation, maintenance, and replacement of cables and other utilities. The International Council on Large Systems (CIGRE) released a Technical Brochure 403 in 2010 through Working Group B1.08 titled “Cable Systems in Multi-Purpose or Shared Structures.” This brochure was developed to (1) establish the appropriate terminology; (2) collect global data on the experience with the use of multi-purpose and shared structures for the installation of cable systems; (3) provide a survey of technical aspects, such as types of cables, design of the structure, installation, mutual impacts among the utilities, maintenance, and operational constraints; (4) provide economic, occupational health and safety aspects, administrative matters, legal aspects, and decision-making process; (5) summarize and review the information to identify the issues that need to be considered when installing insulated cables systems in multi-purpose or shared structures; and (6) recommend guidelines for the use of cables in such structures.

It is important for utilities to prioritize the CIP planning budgets and identify when the best time is to schedule large replacement and rehabilitation for distributed facilities on water or wastewater networks, such as pump or lift stations. This optimized CIP planning is important for short term (5 years) as well as long term to capture the life cycles of the components in pump and lift stations. At the component level, the remaining useful life assessment was conducted with utilizing the industry averages and adjusted with utility institutional knowledge and condition assessments. Critical assets which would drive the project packaging are then identified to come up with the optimized replacement schedules to bundle components into a major overhaul project at the facility level. Genetic algorithms were used to help measure the deferred replacement schedules and the cumulative risks assumed through the deferred replacements. This project investigated finding the optimal timing for replacement and rehabilitation projects at component, facility, and network level for vertical assets. Beyond the facility level optimization, the network level optimizations (facility x versus facility y) were conducted considering the consequence of failure and the resilience factors of the facilities.

Los Angeles Department of Water and Power (LADWP), the nation’s second largest municipal water utility serving over 4 million residents, is upgrading its aging infrastructure, including the existing Los Angeles City Trunk Line (LACTL). The existing LACTL was the first pipeline to serve the City of Los Angeles with water from the Los Angeles Aqueduct. It was completed in 1914 and is a 72-in. riveted steel pipeline with a total length of 63,440 ft. Approximately 28,900 ft of LACTL will be replaced by the City Trunk Line North Project, which is split into Units 1 and 2. Both Unit 1 and Unit 2 will be 54-in. in diameter and will be installed using open cut, slip lining, and micro-tunneling methods. Unit 1 crosses six fault lines and will be a combination of earthquake resistant ductile iron pipe and welded steel pipe, while Unit 2 will be entirely welded steel pipe. The entire City Trunk Line North project is expected to complete construction by 2030.

Geophysical testing can provide important geotechnical and geologic information along proposed pipeline alignments, trenchless crossings, such as a river or creek, or along any location where more information regarding subsurface conditions is needed. Geophysical testing results in continuous profiles of the subsurface that can “connect the dots” between geotechnical borings in areas where the subsurface geology is highly variable and/or hazards may be present. The most common geophysical methods for such work include seismic testing (refraction and MASW), electrical resistivity tomography (ERT), and ground penetrating radar (GPR). Some specific applications include bedrock mapping, hazard investigations (voids and failing soils), stratigraphic analysis, rock rippability, karst investigations, and hydrogeologic investigations. Pyramid Geophysics has utilized ERT to examine geologic conditions in karst environment to identify voids and solution channels along a proposed horizontal directional drill (HDD) alignment in Nashville, TN. Specifically, the geophysical results were incorporated into a geotechnical model using GIS data to present locations where the proposed HDD may encounter air-filled voids and significant weathering/dissolution within a limestone formation. Pyramid has also used a combination of seismic MASW testing and ERT to examine bedrock depth and integrity (e.g., fractures, weathered zones) along sections of alignment both on land and across rivers in submerged environments in Central North Carolina. Correlations were made between seismic velocity thresholds, electrical resistivity levels, and geotechnical boring refusal depths to provide continuous geologic profiles along an alignment exhibiting significant topographic and geologic variability. This paper will provide background on these various geophysical methods and case studies, showing the benefit of combining geophysical investigations with traditional geotechnical approaches.

The Davis Aqueduct is a 22.5-mi-long pipeline made of reinforced concrete pipe ranging in diameter from 84 in. to 21 in. It is the only source of water for several cities in Weber and Davis Counties and in the Great Salt Lake Basin. The Aqueduct sits along the Wasatch front range of the Rocky Mountains and is within the Wasatch Fault Zone (WFZ) for much of the alignment. In addition to the seismic risk, the aqueduct is also at risk of damage from landslides, debris flows, and liquefaction. The Weber Basin Water Conservancy District (WBWCD) serves a population of over 500,000 in Weber and Davis Counties. WBWCD performed a risk assessment, condition assessment, and hydraulic evaluation of the Davis Aqueduct to define its long-term repair and replacement strategy and coordinated that strategy with the State of Utah’s Prepare60 initiative. To mitigate the risk associated with loss of service, the District proposed a parallel pipeline to accomplish two objectives: (1) increase hydraulic capacity, and (2) provide redundancy for the existing pipeline. A goal for the parallel pipeline project was to design the most resilient system possible to help WBWCD maintain high level-of-service goals for critical turnouts. In preliminary design, Brown and Caldwell conducted an alignment study and a geologic hazard assessment to identify, characterize, and define geological and seismic hazards in a potential pipeline corridor from the start of the existing aqueduct to the turnout to Weber Basin’s Davis North Water treatment plant. Seven alignments were considered, and a preferred alignment was selected that prioritized hazard avoidance before hazard mitigation. This paper focuses on the strategy implemented to avoid risks during preliminary design and how the pipe was designed to be resilient when crossing of the Wasatch Fault and passing through three zones with anticipated liquefaction and an area with slope instability. The final design included upgrading the bifurication structure which controls flow at the start of the pipeline, designing a pump station that allows the Davis Aqueduct to divert flow from or into an adjacent canal, and protecting the pipe from landslides on unstable slopes near the terminus of the pipeline and the hydraulic structure which controls flow at the end of pipeline.

In 2015, the Willamette Water Supply Program (WWSP) in Beaverton, Oregon, was completing alignment selection for its new 1.67 m (66-in.) diameter, welded-steel water transmission pipeline. A “pinch point” in the alignment required the pipeline to pass within a reduced public right-of-way, “squeezed” between two electrical substations, and perpendicular to underground control, substation ground fault conduits, communication cables, and overhead transmission lines connecting the two substations. The existing electrical infrastructure and public utilities presented unique design and constructability challenges that included underground and overhead vertical clearances, potential impact of ground faults, and maintaining existing controls. Several methods of addressing the ground fault concerns were evaluated, including encasement, large diameter isolation flanges or joints, increased pipeline depth to attain a minimum separation distance, and modifications to the electrical facilities themselves. This paper presents the reasons for selecting this challenging pipeline alignment, the initial and intermediate mitigations considered, and the selected solutions.

The hazard-resilient joint was developed in 1974 and has since been continuously improved. This joint has been widely adopted as a safety measure for faults, earthquakes, and landslides, because hazard-resilient joint pipelines can absorb large ground displacements due to the joint movements (expansion, contraction, and deflection) and the function of the joint locking system. However, designing a suitable hazard-resilient pipeline for fault displacement requires technical skills. This study proposes a design method for a water pipeline that is resistant to fault displacement by incorporating a hazard-resilient ductile iron pipe pipeline. A case study regarding hazard-resilient pipeline safety evaluation using the finite element method is conducted to assess the design of a hazard-resilient pipeline. Moreover, the assembly time measurements of the joints at an actual site are presented. The obtained measurement results can shed light on the ease of hazard-resilient joint assembly and the estimated assembly cost.

The City of Joliet, IL, has spearheaded their Alternative Water Source Program (AWSP or the Program), partnering with other regional communities and a multi-disciplinary team of consultants, with the goal of providing a sustainable, reliable, and high-quality water supply to support the interests of a new regional water commission and the more than 385,000 people it will eventually serve. Program efforts through 2024 have largely involved the creation of an overall delivery strategy, establishment of governance and managing protocols, and developing program-level standards and frameworks to manage key elements of the Program. This paper provides an overview of how the establishment of the AWSP has been a key instrument for the management of multi-disciplinary teams and an overview of some key elements which are inherent to the planning, design, and implementation of large infrastructure projects.

As of December 2021, the United States Environmental Protection Agency released a new ruling that requires the replacement of lead pipes by the year 2024 across the United States. With this new ruling, communities are analyzing their distribution systems and finding pipes lined with asbestos and lead. Low-income communities have a need to replace pipes, but often lack the budget and resources to hire an engineering consultant to analyze which pipe material to use in the replacement process. To offer guidance to these low-income communities, a theoretical life cycle cost analysis, utilizing data for a small town in southern Virginia, was performed to determine the economic implications of different pipe materials when replacing lead pipes. Further consideration was also made for non-monetary factors, including resistance to rust and corrosion, flexibility of the material, joining methods, the ability to locate after installation, and inefficiencies within certain climates. Coupling the monetary and non-monetary findings, it was found that in the chosen location of this study, PEX piping would be an advantageous material to use when replacing lead service lines. Other communities, however, may consider other non-monetary factors leading to a more ideal material.

This paper will discuss the Yosemite Waterline Replacement Project’s planning and design, review important lessons learned from the construction phase, and will expand on the complexities of pipe bursting and waterline replacement in a heavily congested urban corridor with many technical constraints. Two major waterline breaks in Centennial, Colorado, prompted the Southgate Water District to assess the condition of an existing 18-in. waterline along Yosemite Street. The assessment determined that much of the line was buried at depths exceeding the pipe’s external load capacity. A parallel 16″/18″ waterline of similar characteristics was also found to be subject to the same risk factors. Hydraulic modeling determined that the two lines could be replaced with a single 20-in. diameter waterline. Several conditions made this project a good candidate for trenchless installations. However, dozens of intertie connections, heavy traffic, multiple pressure zones, and deep installation requirements presented challenges to a straightforward removal and replacement or pipe-bursting approach. A mixed approach was used, consisting of fusible PVC pipe bursting, dual parallel installations, and open-cut construction.

The City and County of Broomfield (City) has grown in population in the last 10 years. As with many of the medium-sized utilities in the Denver metro area, the City’s population growth is threatening to outgrow its infrastructure’s capacities. To optimize the use of the existing infrastructure, it is essential to understand hydraulic capacities throughout the entire collection system. As a result of this, the City saw the need to develop a sanitary sewer collection system model as a planning tool for future system expansion and to provide an understanding of current capacity limitations and bottlenecks. This report will use the City as a case study for the numerous benefits hydraulic modeling can provide to a growing utility. As more utilities are faced with hydraulic pinch points in their growing systems, it is more imperative than ever to understand how to best manage risk in areas of restricted capacity and to identify underutilized existing infrastructure that can convey future buildout flows.

Alternative Delivery provides tremendous opportunities to optimize the design and construction of pipeline projects, especially when the team excels at collaboration. This paper explores the keys to successful collaboration developed through multiple successful Design Build and Construction Manager at Risk (CMAR) pipeline projects, which range in cost from $2M to $2.3B USD. The authors include discussion on both practical tips for facilitating collaboration and less tangible strategies that create the environment for collaboration. The paper will outline approaches for creating a collaborative team culture, building trust among team members, and creating open dialogue among stakeholders. Once the team culture is established, the paper explores practical solutions like facilitating input at meetings, tracking review milestones, capturing and resolving input, documenting decisions, and tracking the impacts of implemented changes. All of these strategies are built on open and frequent communication among team members. After establishing the Keys to Success, the authors will highlight real world examples where this process has been used to successfully collaborate on pipeline route evaluations, material selection, design criteria, contingency planning, and bypass pumping with buy-in from the stakeholders. This paper highlights successful strategies, but many of these strategies were developed to address issues where collaboration was not being achieved. The author’s goal is to provide real-life examples that will help Project Managers and Project Leaders engage their teams, gain valuable feedback, capture and track feedback at key milestones, and ultimately deliver successful projects for the Team and Owner.

The project consists of installing roughly 9-mi of 42-in. pipe. The pipeline alignment is along an existing transmission power corridor, within an easement at an abandoned landfill, and along a public right-of-way adjacent to an active landfill. In addition to the challenges arising from the project being located primarily within coastal wetlands of South Florida, the project had to overcome an aggressive schedule, with design, permitting, and installation needing to be completed within 2 years of notice to proceed. The challenges observed on this project included difficult site conditions, with the contractor having to battle a high groundwater table, unstable soils, and tidal influences, coordination with local and federal stakeholders, installation parallel to an existing 54″ PCCP force main, and high voltage transmission lines. This paper will focus on discussing the various challenges observed and the solutions and strategies implemented to overcome the setbacks.

This paper discusses the crucial role three-dimensional (3D)-based drawings and building information modeling (BIM) files play in the development of standard details for construction. Historically, standard details used by many utilities were based on sketches and unscaled two-dimensional (2D) drawings which often led to costly erroneous interpretation, delays in construction, and overall non-conformity in construction. The advent of 3D and BIM digital technologies has helped eliminate these issues by allowing for realistic designs with increased precision, better visualization, and fostering an efficient project management system. Furthermore, the standardization of details facilitated by 3D and BIM technologies enhances repeatability across projects, saving time, resources, and contributing to the overall sustainability of the construction industry. As an example, we will discuss the processes involved in the implementation of 3D drawings and BIM files into updating the District of Columbia, Water and Sewer Authority Standard Details, and the overall benefits achieved across the utility.

The City of San Mateo, CA, commissioned the planning, preliminary design, and final design of the Basins 2 and 3 Collection System Improvements (CSI) Project (herein referred to as the Project) with an objective of mitigating Sanitary Sewer Overflows (SSOs) within a large section of the City. To achieve the objective, the project identified locations in the City’s sewer system that were under capacity by utilizing hydraulic modeling to pinpoint areas of the sewer network prone to SSOs during wet weather events. Results of the hydraulic modeling led to development of several sewer design packages to enhance the collection system’s capacity to mitigate SSO occurrences. Each design package utilized various construction techniques and a variety of pipe materials. This paper provides a project case study and focuses on the details of the engineering solutions and the rationale behind why the selected pipeline materials were chosen.

The Vancouver International Airport (YVR) is undergoing a project to realign the westernmost 2.2 km section of Ferguson Road on the Sea Island. This involves extending the existing Ferguson Road at McDonald Road to provide an improved corridor with wider travel lanes, paved bike shoulders, and a new multi-use pathway to accommodate all road users, the installation of two 450 mm Polyvinyl Chloride (PVC), fully restrained watermains and associated appurtenances, and drainage, electrical, and communication infrastructure to service future developments along Ferguson Road and the adjacent wastewater treatment plant on Iona Island. The Project addressed several design and construction considerations and constraints that ultimately impacted the final geometry, configuration, and material selection of the proposed watermain infrastructure. This paper summarizes how the noted considerations and constraints influenced the final design of the twin watermains, how the watermain material and restraint system was selected, and the Project construction progress.

The Central Avra Valley Storage and Recovery Project (CAVSARP) was designed to recharge and recover Central Arizona Project (CAP) water in response to water quality issues in Tucson and is supplied by 60-in. welded steel pipe (WSP) and a 54-in. high-density polyurethane (HDPE) pipe. As a pressure system, the head characteristics have been a challenge, since CAVSARP was commissioned. There is a large elevation difference upstream to downstream, so control valve cavitation is a concern at the upstream turnouts with downstream turnouts experiencing low head issues. In 2019, the HDPE transmission main suffered a pipe failure, a 100-ft longitudinal crack. Though pipe replacement was recommended, replacing the flow control valves with plug valves was determined to be a viable alternative. After evaluation of several valves, a 20-in. eccentric plug valve proved to be a suitable solution for CAVSARP’s conditions and saved the utility’s CIP budget $18 million by avoiding pipe replacement.

Seismic joint performance for ductile iron pipe (DIP) products has seen significant advancements in recent years across the industry. Procedures to establish the minimum required DIP seismic joint performance requirements are lacking in the industry. This paper describes an approach to establish minimum seismic joint performance requirements based on procedures developed as part of the $1.6 billion Willamette Supply Program (WWSP, Program). The WWSP includes over 30 mi of large diameter water transmission line in the seismically active Pacific Northwest region which is at risk of a magnitude 9.0 Cascadia Subduction Zone earthquake. For the Program, boltless segment joint DIP was identified as the required type of DIP joint. Complicating factors related to delivery schedules, supply chain issues, and the need for field flexibility during installation, however, made the use of boltless segment jointed DIP infeasible in some cases. To address this, the Program developed new alternative procedures to utilize lower strength, but more available products without compromising its high seismic performance standards. This paper describes these new procedures established related to alternatives to exclusive use of boltless segment jointed DIP.

Oklahoma City (City) uses the Atoka pipeline system to transfer raw water from the Atoka Reservoir in southeast Oklahoma to the Stanley Draper Reservoir located in the southeast part of the City. This system was operational in 1964 and consists of six pumping stations and a 100-mi (161-km) long/60-in. (1,500-mm) diameter prestressed concrete pipeline. The existing surge protection system consists of a combination of one-way steel tanks (major surge facilities) and air vacuum valves (minor surge facilities) located along the pipeline alignment. A condition assessment of the existing major/minor surge control facilities for this pipeline was performed, and it was determined that most of the facilities need to be replaced. Surge modeling was performed, and matrix evaluation was developed to compare the conventional and bladder-type surge tank options based on several criteria. This paper will discuss the lessons learned from this project during design and construction.

Clear and concise specifications for a pipeline project can avoid numerous issues for owners, designers, and contractors. During the bidding process, if specifications can easily be interpreted in different ways by different bidders, the bids may not be comparable. Several suggestions are presented in the paper to assist engineers with the task of preparing specifications that minimize the opportunity for misunderstandings, bid protests, project delays, change orders, claims, and cost over-runs. Among several purposes of the specifications, the intent of a well-written specification is to set up the contractor for a successful project. This benefits not only the construction contractor, but also the owner and general public.

The AWWA M11 Harness provides a means of restraining non-restrained pipelines operating under pressure. In areas where gasketed joint pipe and non-self-restraining couplings are subject to thrust resulting from internal pressure, an option to mitigate the thrust is to harness across the joint. However, a closer look at M11 reveals deficiencies, including overstressed back ring and gusset plates, insufficient weld size, lack of weld access holes, inadequate load transfer between back ring and gussets, improper weld types and underestimate of strength, oversize holes too small for easy field assembly of tie rod and nuts without washers to spread load, and complex double-curved geometry of skewed gussets resulting in welding assembly issues. This paper addresses the deficiencies with current M11 harness and provides suggestions to improve the design and fabrication with the goal achieving structural code compliance and improved safety for water projects. Example calculations are provided.

Aeration systems add air to water in water and wastewater facilities as part of the treatment process. To sustain required airflow rates and properly aerate water, engineers must adhere to good design principles while factoring both standby and future plant expansion needs in their design. Aeration piping design begins at the process level. It involves calculating and selecting pipe sizes, valve locations, control mechanisms, and blower layout. This paper concentrates on design considerations for the steps that follow: movement absorption, thermal expansion, material selection, design temperature, and piping layout. It covers design issues, considerations, and solutions to prevent potentially catastrophic issues during system construction, commissioning, and maintenance.

Water distribution systems are vital in delivering water to a large population. When choosing a pipeline material, sustainability should be considered on top of the direct cost as public entities strive to lessen their environmental impact. This paper provides a life cycle analysis of three different pipeline materials: ductile iron, polyvinyl chloride, and high-density polyethylene. Carbon dioxide emissions are used as the metric for environmental impact and sustainability, because they are known to be a major contributor to climate change. The life cycle of the pipeline material for this analysis consists of fabrication, transportation, installation, and operational use. The analysis indicates that the carbon dioxide emissions range from 420 to 570 pounds of carbon dioxide per foot of 8-in. pipe depending on the pipeline material. High-density polyethylene pipe had the lowest carbon dioxide emissions and ductile iron had the highest with the given parameters outlined in this paper.

Knowing the accurate hydraulic friction factor of a pipe is important to properly understand and design various aspects of a pressure or gravity pipeline project, such as pipe size, flow velocity, and pump size. To aid in determining values that should be used for design of PVC pipe, hydraulic laboratory testing on new PVC pipe has been performed, as well as field C-Factor testing on a 40-year-old PVC water main. This paper will provide the findings of the laboratory and field tests, and it will present how hydraulic factors, such as C-Factors, vary with Reynold’s number and pipe age. This paper will also discuss the pros and cons of performing laboratory and field hydraulic tests, along with how these test results coincide with current industry recommended values.

This paper introduces a novel design approach based on finite element analysis (FEA) for flexible and anisotropic liners, specifically aimed at large-diameter pipelines and the retrofitting of non-circular conduits. The objective is to enhance flow conditions and reduce sedimentation, particularly in combined sewer systems. The FEA model is versatile, also applicable to point repair systems for hazardous fluid transmission lines. Overcoming challenges in composite material applications, the proposed model is validated through laboratory testing and comparison with existing methods, demonstrating robust correlations. It is successfully applied in designing FRP liners for a 17.5-ft sewer interceptor and a carbon fiber-based point repair system for underwater oil pipelines. The FEA model proves effective for trenchless structural rehabilitation, addressing complexities in anisotropic and flexible liner applications for point repair, large-diameter pipelines, and non-circular conduits.

Crotch plates are used to reinforce wyes and outlets on welded steel pipe; however, they represent a challenge, since complex geometry may be unfavorable to welder access. Inadequate welder access can have a negative effect on weld quality and compromise the strength and serviceability of these important components of water conveyance systems. This paper examines welder access given the complex geometry of crotch plates, welding details, welding processes, welding position, and limitations imposed by welding codes and provides guidance to designers and fabricators of crotch plates. Example problems are presented with assistance from a contour chart and table that circumvent rigorous calculations to simply understanding of welder access to crotch plates.

The Northeast Boundary Trunk Sewer (NEBTS) was constructed between 1879 and 1894 and ranges from approximately 6 ft (1.8 m) to 23 ft (7 m) in diameter and is approximately 28,800 linear feet (LF) (8,778 m) in length. In 2018, DC Water commissioned a report on the condition of various sections of the sewer. Based on the results of the report, two sections/segments of the sewer required rehabilitation. Segment 1 has a circular cross section with a diameter of 22 ft (6.7 m). Segment 2 has a 9 ft (2.7 m) by 6 ft (1.8 m) wide egg-shaped cross section. DC Water tasked the Greeley and Hansen/Ramboll Joint Venture with analysis of rehabilitation alternatives. Once geopolymer was selected, the Joint Venture was tasked with a Finite Element Analysis to determine the thickness of the liner. Construction is anticipated to begin in Spring 2024 and finish in Summer 2025.

ASCE Manual of Practice 145 (MOP 145), Design of Close-Fit Liners for the Rehabilitation of Gravity Pipes, provides design guidance for close-fit liners in gravity pipeline applications for a wide range of cross sections. With the increase in functionality for non-circular cross sections comes a significant increase in the geometric information required to facilitate the design process. Our paper involves a review of multi-sensor sewer inspections (i.e., LiDAR or laser scanning and SONAR) completed in Winnipeg, Manitoba, Canada, and the impact of the observed variation in cross section has on the required liner thicknesses using the MOP 145. The findings of this research are concluded with recommendations for data collection by owners and engineers during the design phase to facilitate a fair and level tendering process. The intent is that our findings will help the industry in developing tailored tendering strategies aligned with MOP 145.

An industry-wide movement among cement manufacturers has impacted requirements of many current AWWA water pipe standards, including AWWA C300, C301, C302, C303, and C205. These standards all reference the use of ASTM C150 Portland cement for use in the manufacture of concrete and mortar used in the manufacture of concrete and steel pressure pipe, but in the United States and Canada, many producers of ASTM C150 Portland cement have already shifted their production at specific plants from Portland cement to Type IL blended cement, also known as Portland-limestone cement or PLC, meeting the ASTM C595 Blended Hydraulic Cements standard. Due to an evolving cement industry, the American Concrete Pressure Pipe Association and the AWWA Steel Water Pipe Manufacturers Technical Advisory Committee have requested addendums or revisions to the aforementioned AWWA standards to recognize ASTM C595 Type IL cement and permit its use in the manufacture of concrete and steel pressure pipe. This paper provides an in-depth discussion of the industry changes, the work completed by the pipe organizations to vet and request inclusion of Type IL meeting the ASTM C595 standard, and lessons learned while making the conversion.

The Trinity River Authority of Texas (TRA) Segment 09BC-1 project is located within TRA’s Central Regional Wastewater System (CRWS). The CRWS service area is the largest within TRA, serving 21 customers by collecting and conveying wastewater flow through over 200 mi (322 km) of pipelines to its treatment plant. The Segment 09BC-1 project includes the replacement of five miles (8 km) of 30- to 54-in. (762- to 1,372-mm) unlined reinforced concrete pipe (RCP) originally constructed in 1984. The design and construction of the replacement pipeline were completed in three phases and involved extensive coordination with recreational properties, including a golf course owned by an international airport and a city park system with baseball fields, a dog park, and trail system. The construction of each phase highlighted certain challenges, such as maintaining project schedule for easements with time constraints, material waste due to unlocated utilities, and review of construction submittals for newly approved manufacturers.

Annular pressure analysis that determines the likelihood of hydraulic fracture occurrence is critically important for evaluating the feasibility of horizontal directional drilling (HDD). The traditional method of annular pressure analysis in HDD makes insightful comparisons between minimum required annular pressure, P_min, and maximum allowable annular pressure, P_max, along the bore path. However, such a method seems deterministic rather than considering the potential variability in estimates of annular pressure (both P_min and P_max) due to the uncertainties within the parameters and models used. This paper proposes a concept of probabilistic risk assessment that allows incorporating such uncertainties in the annular pressure analysis in HDD. For a better understanding, the newly proposed concept of probabilistic annular pressure analysis in HDD is discussed in relation to the probabilistic method used in other geotechnical engineering applications. Lastly, information required for developing risk criteria for evaluating the risk of hydraulic fracture in HDD is presented.

North Harris County Regional Water Authority (the Authority) continues the implementation of its Groundwater Reduction Plan (GRP), which is to replace the use of groundwater by providing surface water (conversion) in the North Houston area. The Authority’s Project 37 represents a critical component of the Authority’s system to provide surface water to its customers in the northwest portion of its service area. The original plan for Project 37 included new transmission water lines as well as a repump station to serve the project area. The route study for Project 37 had several challenges, including: coordination with a third-party consultant for hydraulic modeling efforts, coordination with numerous Municipal Utility Districts and public agencies, identifying public and private utilities, limiting the impact to the public in fully developed neighborhoods, and evaluating ways to reduce cost. The final route for Project 37 consists of approximately 41 mi of water lines ranging in diameter from 42 in. to 12 in. and delivering surface water to 23 water receiving facilities. Through unique ideas and solutions, the final route also eliminated the need for the new repump station, eliminating the expenses on construction, operation, and maintenance of the station. Overall, the selected Project 37 route allows the Authority to reduce the amount of funding needed to construct Project 37, save money in operations and maintenance, and meet the GRP conversion goals.

A large part of a city’s growth is major transportation and transit projects. These major transit projects are a once in a generation opportunity to move people and vehicles on a large scale. In the fall of 2020, the citizens of Austin passed a $7.1 billion transit plan called Project Connect, a comprehensive transit plan aimed at enhancing public transportation in Austin, Texas. It is comprised of a new light rail transit (LRT) system, an expanded bus system, and a transition to an all-electric vehicle fleet. The Austin Transit Partnership (ATP), an independent local government organization formed by the City of Austin and CapMetro, manages the Project Connect investment, including design and construction of the new transportation infrastructure. Coordination is ongoing between ATP, CapMetro, Austin Water (AW), Austin Energy, Watershed Protection, numerous planning and design consultants, and the public for implementation of Project Connect. The Pape-Dawson Team (PD) was selected and contracted by the City to evaluate specific major utility conflicts identified by AW staff dedicated to this project. The AW Team has been working independently from the Project Connect Team responsible for the light rail improvements. Typically, large transit focused projects do not consult utility companies until design has significantly progressed. By getting ahead of the game, AW has been able to evaluate alternative alignments for their proposed pipeline assets and relocation of their existing infrastructure without the constraints of a transit design that is already set. This approach allows AW to provide alternatives that meet their best interest for serving their customers and future operations and maintenance (O&M).

Selecting an alignment in progressively developing corridors becomes increasingly more challenging every day. Property owners are less willing to grant easements and developers do not want to give up real estate, or for their developments to be disrupted by the process. In addition, adequate space for permanent and construction easements is very limited within these busy areas. These factors make justifying alignment paths, the workspace needed, and the project’s purpose of critical importance. Adequate justification of a selected alignment and associated easements is not only important to help explain the benefits of the project to impacted owners, but also to protect and justify the project should an eminent domain process be required. This paper will present a method developed to objectively analyze various alignment alternatives for two different types of projects: 10 mi (16.1 km) of 24-in. (610 mm) to 42-in. (1,067 mm) transmission main and 3 mi (4.8 km) of parallel 36-in. (915 mm) force main.

Lee County Utilities undertook an expansion at the North Lee County Water Treatment Plant in Fort Myers, Florida, adding six raw groundwater production wells and a raw water transmission main with pipe up to 30 in. in diameter to meet North Lee County’s growing water needs. The project faced challenges due to limited pipeline routes, narrow right-of-way corridors, deep ditches, and restrictions on daytime road closures. There was only one practical route that connected all six well sites and delivered water from these sites to the plant. The design had to overcome challenges noted above, as well as concerns about public convenience, environmental considerations, and future maintenance. Lee County Utilities’ existing preference for HDPE pipe opened the door for installing over 87% of the transmission main via 27 horizontal directional drills for approximately 35,000 linear feet. This case study highlights the use of horizontal directional drilling trenchless technology to navigate the previously mentioned challenges in a limited pipeline corridor.

The Lake Nighthorse Raw Water Supply Line project in Durango, Colorado, is being designed to convey water from Lake Nighthorse to the Santa Rita Pump Station (SRPS). Taking into consideration factors ranging from cost to cultural resource protection, an alternative alignment analysis was performed to determine the best route of travel for the pipeline. Assigning each potential route within the same reaches an individual score to be compared against each other guided the discussion of which route for each reach appeared to be the best option. This exercise provided perspective on the truly important factors to consider, necessitating adaptability and compromise to be made from all stakeholders to maintain holistic efficiency for the entire pipeline system.

Phoenix embarked on a major potable water transmission project in 2018 that included over 15 mi of 42″−66″ pipelines, three new booster pump stations along with numerous system interconnections and pressure reducing stations. At the beginning of the project, the City selected a program manager, engineers, and construction manager at risk (CMAR) contractors for each project component. This proved beneficial especially for the Segment 1–66″ pipeline portion of the project. Segment 1 is located along a major north south corridor in the center of the City’s water service area, including through a mountain preserve, next to a dam, sensitive neighborhoods, along and under a state highway. In addition to COVID, supply chain issues, and cost escalation, the City and its team overcame numerous other challenges, including neighborhood opposition at the initial stages of the project, numerous jurisdictional washes within the alignment, designing, and building a pipeline in a 40′ wide corridor with a steep slope up to homes with backyard pools on one side of the corridor and a 20′ tall highway sound and retaining wall on the downslope side. To avoid going under a 30′ long 20′ deep storm drain drop section and other critical transmission pipelines next to the highway wall, the team came up with a plan to use an existing planter space between the drop section and the wall to route the pipe above grade, protected with concrete encasement. The encasement is screened by a wall matching what was once a planter. Low water use cactus and shrubs were placed in the planter to return area to its planter aesthetics. Within the mountain preserve, the depth to rock is between 3 and 4 ft and testing showed it to have an unconfined compressive strength from 3,000 to 20,000 psi. Due to the fact that there is a major Corps of Engineers flood control dam in the preserve, blasting for trenching was not allowed. The engineers and CMAR worked together to understand the trenching conditions including completing rock coring and testing as well as test excavations with various excavation methods and equipment. In addition to the presence of hard rock, testing and geologic observations showed the rock to be tilted with variable depth particularly along the location where the pipeline needed to cross under the freeway. This required the team to conduct additional investigations, included drilling a boring in the middle of the freeway at night and implementing additional monitoring of the tunnel boring machine excavation under the freeway during construction. This presentation will describe the challenges and how the City and its engineer and CMAR team worked through them resulting in a successful project meeting the Water Services Department’s goals.

Due to the ongoing desire to separate combined sewers and increase stormwater capacity, the City of Lancaster engaged Jacobs to design a new stormwater trunkline. The main purpose of the project is to reduce combined sewer overflows and increase the capacity of the stormwater collection system through the addition of a new north-to-south stormwater trunkline with connections to smaller collection branches through a busy area of the city. Following the planning phase of the project, the engineering team kicked off the design refinement for their draft design submission. While the initial horizontal alignment looked good visually, once the vertical alignment got underway, the vast amount of existing utilities and grade changes challenged the original alignment. The team had to look at multiple alternatives through several reaches of the project to be able to navigate these obstacles while keeping the needed capacities. Additionally, the existing combined sewer system’s pipes which are 120-in. and 96-in. in diameter run parallel to the proposed stormwater trunkline through a tight corridor with steep slopes and critical utilities around as both try to reach the same outfall point. Geotechnical conditions and the applicability of trenchless installation were evaluated and implemented into the design. This paper will go over some of those challenges mentioned, how the project will be phased, as well as how the team tried to maintain overall hydraulic capacity while detailing the design of over 4,000 LF of 12-in.–66-in. sewers.

The City of Boulder, Colorado, is installing a new 2.5-mi sanitary sewer transmission main to convey the majority of the city’s wastewater flows to the Boulder Water Resource Recovery Facility. The final mile of the 42-in. and 54-in. diameter interceptor runs through Sawhill Ponds, owned by the State of Colorado, and Walden Ponds, owned by Boulder County, before connecting into the headworks of the wastewater treatment facility. These critical habitat areas and wetlands are beloved and include a trail network that is well used by the surrounding public. To design the pipeline through this unique area, the project team coordinated closely with the city, county, and state to identify critical habitat and to carefully coordinate the alignment to navigate existing wetlands, trees, and structures. Addressing these challenges also required a redesign of a dam spillway separating two of the ponds that the new 54-in. interceptor crosses between, as well as designing for a crossing of a FEMA-certified levee into the treatment facility. Furthermore, due to the shallow grade (3.8′ to top of the 54-in. pipe), the project team had to work closely with manhole and pipeline suppliers to design custom shallow manhole structures that are traffic rated, allow for safe operation, and align with the desires for the use of the future trail system. This case study reviews how the project team weighed multiple approaches to mitigate the unique design challenges for this project. By communicating closely with stakeholders, suppliers, and permitting agencies, the project team successfully selected an alignment and prepared a design that not only resolved the unique site’s challenges, but also improved the Sawhill Ponds and Walden Ponds wetland areas. The presentation includes an assessment of the overall constructability through this area as well as the unique design details that were prepared.

The Southern Nevada Water Authority (SNWA) has initiated the Stage II Reliability Upgrades (S2RU) Project in response to the increasing risk posed by aging yet critical conveyance infrastructure which supplies a significant portion of water to central Las Vegas. The Project aims to fortify the water supply system by introducing redundancy and reliability through the construction of the new Monthill Pumping Station (Monthill PS) and an accompanying 66-in. diameter interconnect pipeline. This pipeline will augment existing pumping station (PS) capacity by providing a dependable redundant route for supply of treated water, both when the existing pumping is in operation, and as replacement capacity during scheduled maintenance periods. The Monthill PS will deliver up to 90 million gallons per day (MGD) through this new pipeline and will not only alleviate the pressure on existing pumping facilities, but also enhance system efficiency and reliability by establishing a two-way flow between existing transmission laterals. The S2RU Project is not without challenges. This paper addresses the significant obstacles and unique design solutions associated with the design of the Monthill PS and interconnecting pipeline, including such challenges as a tight urban residential pipeline corridor alignment, coordination with existing utilities, a trenchless roadway crossing, and shallow groundwater. Through these design solutions that will be utilized to produce construction documents along with teamwork between SNWA and the design engineer, this project will ensure a reliable and robust water supply for the vibrant heart of Las Vegas.

“Two roads diverged in a yellow wood, /And sorry I could not travel both”—not all paths are created equal, and for many projects, upfront route studies can identify benefits and pitfalls of potential corridor options prior to finalizing route selection and proceeding with survey, design, permitting, and construction. This paper presents several case studies of preliminary route evaluations using a set of key criteria, data collection, and assessment techniques. This paper will explore techniques and methodology successfully utilized on multiple projects, such as aerial, topographic, utility, regulatory, property, and GIS information, to determine the viability of corridor options available for pipeline projects by open cut and trenchless installation methods. Understanding and addressing potential constraints during the planning phase of a pipeline design provide maximum opportunity for an optimized pipeline route that benefits the owner, schedule, budget, and other project drivers.

Delays to capital projects are costly both in time and expense. One of the least determinable elements of project progress is the permit approval phase. A careful review and understanding of the legislative process and regulatory rules provide opportunities to accelerate permit approvals. In certain situations, the adjustments to a project commencement date, the scale of a project, and/or even how a project are defined can significantly reduce permitting requirements. This paper will explore the intent of certain local, state, and federal permits and the regulation language associated with these rules. It will discuss permit exceptions and how these clauses can negate the need for a permit, allowing the project to remain compliant with safety and environmental regulations.

The Navajo-Gallup Water Supply Project (NGWSP) is a major infrastructure endeavor that will convey a reliable municipal and industrial water supply for future generations on Navajo Nation land and the Four Corners Region. The project will service northwest New Mexico, including the eastern section of the Navajo Nation, the southwestern portion of the Jicarilla Apache Nation, and the city of Gallup via approximately 300 mi of pipeline, 19 pumping plants, and 2 water treatment plants. The NGWSP has a congressionally mandated deadline for completion by December 31, 2029. There are currently 15 crossings along the NGWSP that have been analyzed for the most effective method of crossing and found that a trenchless installation is more beneficial than open-cut excavation at those locations. Throughout the preliminary-design, design phase, and construction phases of NGWSP, there have been many challenges with Horizontal Directional Drills (HDD) that have resulted in lessons during construction that have changed the way the Bureau of Reclamation (Reclamation) handles HDDs.

Pipe infrastructure is the underpinning of our health, safety, and economy. With proper design, polyvinyl chloride (PVC) pipes have withstood a wide range of operating pressures, ground motions, and exposure to aggressive environments. Corrosion-free durability, broad in-service success, and cost effectiveness have made PVC pipe a very popular choice for water distribution and transmission. While the in-service failure rates for PVC pipe are relatively low, all pipe products experience failures. To keep PVC pipe infrastructure working better, safer, and longer, it is important to understand PVC pipe’s service life factors and the underlying causes for in-service failures. In this research, previous studies and investigations which were carried out to predict the lifetime and/or mechanical failures in buried PVC pressure pipelines are comprehensively reviewed. The existing publications are analyzed and discussed regarding PVC pressure pipe failure rates and the causes for mechanical failures are delineated. Determining whether a particular failure is isolated, or indicative of a larger problem, requires accurate identification of the root cause. The aim of this research is to examine and classify the results from previous investigations. Different causes and types of mechanical failures are explained. The findings developed from this review indicate advantages, limitations, and research gaps in this area. Finally, recommendations for improving in-service performance and future research directions are presented.

The City of Winnipeg retained Pure Technologies, a Xylem brand (Pure Technologies), to conduct a condition assessment of the prestressed concrete cylinder pipe (PCCP) on the 1,650-mm Branch II Aqueduct in Winnipeg, Manitoba. On September 21, 2022, Pure Technologies used its proprietary PipeDiver platform, a non-destructive electromagnetic inspection technology to locate and identify pipes that have broken prestressing wire wraps. The inspection covered a cumulative distance of 18.63 km and spanned a total of 3,826 pipes from the Deacon Water Treatment Plant to the South Cell of the Wilkes Reservoir. Analysis of the data obtained during the inspection determined that 33 pipes in the 1,650-mm Branch II Aqueduct displayed an electromagnetic anomaly consistent with prestressing wire damage, ranging from 5 to 20 broken wire wraps.

Utah State University (USU) has just completed the most comprehensive water main survey ever undertaken in the US and Canada for the purpose of understanding how utilities use pipe in their systems and determining the performance of different pipe materials. Of the 802 basic survey respondents, 791 participants provided water main distribution data having a total of 399,812 mi of pipe. This pipe mileage represents 17.1% out of an estimated 2.33 million miles of pipe that is installed in the US and Canada, making this the largest survey of its kind. A full USU report of these most recent survey results was published in December of 2023. Similar survey results were published by USU in 2012 and 2018. When the most common pipe materials (cast iron, ductile iron, PVC, and asbestos cement) were compared, PVC had the lowest overall failure rate and cast iron had the highest at 2.9 and 28.6 breaks (100 mi-year), respectively.

Current full-scale experimental practices for pipes subjected to ground movements are limited to simple, abrupt ground movement profiles, such as normal faults; however, more complicated ground movements from earthworks and ground subsidence occur in the field. A new facility is being developed at Queen’s University to simulate these more complex ground movements. The facility is the next generation of the laboratory’s normal fault simulator (the “Split Box”) and consists of a full-scale soil chamber with a stationary floor and three independent moving floor sections. Hydraulic actuators will be installed at both ends of the facility to permit investigations of relative axial ground movement and upheaval buckling. These new features will facilitate improved understanding of soil–pipe interaction problems. The conceptual design of the facility is discussed and ABAQUS soil modelling is used to verify the feasibility of creating a versatile set of vertical ground movement profiles at depths practical within a laboratory setting. The novel techniques that will be implemented in the new facility form an important next step in modeling and understanding the response of buried pipelines subjected to differential ground movement and are expected to aid in the improvement of pipeline design and assessment.

Pipe diameter is a key factor in water main design. Decisions around what diameter to use are generally driven by hydraulic considerations, such as offering sufficient flows and residual pressures during fire suppression usage. Considerations of the relative failure risks of different diameters are rarely taken into account; however, this novel research finding suggests that diameter is a much more significant factor than was previously understood. Previous studies have noted that small diameter mains are responsible for more leaks than transmission mains, and that customer services suffer more leaks than either of the two. These observations have come through the professional observations of experienced engineers and from small scale studies. Other observations have noted potential errors in the theory underpinning the design standards for small diameter pipe. None of these have previously translated to a systematic examination of the relationship between diameter and failure risk. This paper presents a novel finding of an inverse-linear relationship between pipe diameter and failure risk per unit length of pipe. This finding is supported by the largest database of pipe failure records ever compiled, including over 10 million pipe-years of records from nine utilities across North America, Europe, and Asia. These records show a clear and strong negative correlation between diameter and failure risk across all pipe materials. When the inverse of diameter is considered, the relationship with failure risk appears to be linear for many materials. This relationship has two major implications. First and foremost, the fact that small diameter pipes fail as much as 100x as frequently as large diameter mains should be incorporated into risk considerations during pipe design and asset management decisions. Second, it offers a novel and useful normalization: failures per million pipe diameters of length per year. This normalization provides a more robust and consistent measure of failure risk than the industry norms of failures per 1,000 pipes per year or failures per 100 km (or 100 mi) per year. That in turn allows the actual failure risk posed by other factors (in particular pipe material, which often correlates with diameter) to be more clearly demonstrated, exposing some misconceptions about the relative risk of different pipe materials.

The Seton Storm Trunk and Outfall to the Bow River were designed to convey clean stormwater flows from the Rangeview and Ricardo Ranch neighborhoods being developed in southeast Calgary, Alberta, Canada. The Seton Storm Trunk has a total length of 2.3 km with pipe diameters ranging from 900 to 1,500 mm and provides storm outlet servicing for a total area of 614 ha. Approximately 2.0 km of the storm trunk was installed using conventional open-cut installation. The main challenge was when the storm trunk reaches the top edge of the Bow River escarpment where the ground elevation drops more than 50 m in a horizontal distance of approximately 175 m. Several groundwater springs along the toe of the escarpment where it meets the Bow River floodplain make the installation even more challenging. There are also several known areas where soil creep is occurring to the east of the storm trunk alignment, likely due to the shallow groundwater table in combination with surface water drainage paths. A review of available options and a triple bottom line analysis, where economic, social, and environmental issues are evaluated equally, determined that Horizontal Directional Drilling (HDD) was the most viable and cost-effective option that would have the least environmental and social impacts on the escarpment slope. To meet the hydraulic requirements of the project, it was determined that a 900 mm HDPE pipe installed at a slope of just over 14% was required for capacity. At this slope, an energy dissipation structure was required at the bottom prior to the flow being discharged through the outfall to the Bow River. The energy dissipation uses an innovative design that uses hydraulic jumps to dissipate the energy at the bottom of the escarpment. The drill entry was located approximately 135 m back from the top of the escarpment, 60 m north of where the gravity storm trunk connects to the HDD section through a specially designed hydraulic drop structure. The structure and piping include air management features to avoid air entrapment in the pipe, thus compromising the hydraulic capacity of the system. This paper presents an overview of the challenges, both geotechnical and hydraulic, that the design team had to overcome, which resulted in the very complex HDD plan necessary to complete the work.

A transient analysis was completed for the 341 megaliters per day (ML/d) (90 MGD) Monthill Pumping Station (PS) that will provide redundancy for the 681 ML/d (180 MGD) Hacienda PS—a critical facility serving the central area of Las Vegas. A comprehensive transient analysis was carried out to identify and mitigate potentially damaging water hammer conditions with the Monthill and Hacienda PS’s operating alone, as well as concurrently. This paper will review the use of direct-on-line starters versus soft-starters; using non-slam check valves in conjunction with pump control valves; results with a throttled air chamber; and methodology used to recommend pump control valve opening and closing times.

Leaks in water distribution networks can cause considerable water wastage, infrastructure damage, and contamination. Various solutions have been developed for leak detection. Previous researchers have applied deep learning, utilizing traditional loss functions, such as F1 score or accuracy. However, these approaches may oversimplify the real challenge of quickly repairing leaks. This study aims to develop a Convolutional Neural Network (CNN) for leak detection, trained with the specific objective of optimizing leak detection. A synthetic data set is developed by simulating leaks using EPANET in Python. The leakage detection model was trained with a modified loss function based on the distance to the actual leak. Results show that the use of the modified loss function led to better leak detection accuracy than with the traditional loss function. These findings provide insights into strategies for using novel deep-learning models to efficiently detect leaks.

Cities around the world are challenged with conveying gravity sewer flows across rivers, waterbodies, and other low-lying obstacles through use of inverted siphons. Inverted siphons are often constructed to convey gravity sewer flows across rivers, waterbodies, and other low-lying obstacles. By their very nature, they present a number of engineering challenges that, if not adequately addressed in design, can challenge the construction, operation, inspection, and maintenance of the infrastructure over its design life. This paper will discuss some of the unique challenges in design, construction, operation, maintenance, and condition assessment and suggest some best practices to overcome many of the unique challenges.

Washington Suburban Sanitary Commission (WSSC) is among the largest water and wastewater utilities in the United States, serving approximately 1.9 million residents in Montgomery and Prince George’s County, Maryland. WSSC’s Development Services Division (DSD) has used different methodologies for the last 40 years to analyze the capacity of the water system for new developments. DSD uses Hydraulic Benchmarks, skeletonized models, and a modified all pipes water model developed by WSSC’s Planning Division to do these hydraulic analyses. The Planning all-pipes model has been used primarily for Master Planning and provide support to different stakeholders in WSSC, such as Water Condition Assessment, Operations, and Asset Management. WSSC has decided to compare the different methodologies and a start to build a new all-pipes model that better reflects the changes in demand allocation, pipe roughness, and capacity. This paper will discuss the different methodologies and what are the next steps to update the all-pipes water model and calibrate it.

A process and matrix are presented for utilizing buried hazard-resilient pipelines. The process and matrix were developed by a group of USA and Japan researchers who worked to improve the understanding of hazard impacts on buried water pipelines. A wide range of natural hazards, many having increased intensity from climate change, are known to affect the performance of buried water pipelines and the ability of water systems to provide services. Hazards impose strains through different mechanisms (e.g., thermal and ground displacement) on pipelines that may lead to damage. Resilient pipelines are beneficial for managing the strains imposed by a wide range of events. The matrix lists hazards and their potential impacts on buried pipelines, service disruptions, and societal consequences. The matrix helps guide pipeline owners to identify, prioritize, and plan for the use of hazard-resilient pipelines. The matrix and an associated process for its implementation into practice are proposed in order to identify the need for and application of hazard-resilient pipelines.

The Summit Pressure Zone South Pipeline Replacement, Phase 1 project included approximately 5,000 linear feet (LF) of 24-in. steel pipeline in various streets in Berkeley, California, in addition to 700 LF of 36-in. high density polyethylene (HDPE) and 500 LF of 22-in. HDPE pipelines to cross the Hayward Fault in Claremont Avenue on the Oakland/Berkeley border. The transmission pipelines cross the Hayward Fault in an area which experiences significant ground movement resulting in several previous pipeline failures. East Bay Municipal Utility District (EBMUD) worked with researchers at University of California, Berkeley (UCB), to develop a system that would be able to monitor and measure pipeline strain in a robust, sensitive, distributed, and accurate way. The team explored various technologies and applications to determine which were most viable. The distributed fiber optic sensing (DFOS) system was selected as the most appropriate method to achieve the goals. Installation of the HDPE pipelines in this area was difficult due to field conditions, and installation of the fiber optic cables in the trench presented further challenges. A collaborative contractor and an adaptable team from EBMUD and UCB allowed the project to overcome these challenges and install a successful project. The system was brought online in summer 2022, and the team has already received some interesting data about the pipeline behavior at the Hayward Fault crossing.

Pipelines transporting water resources are often constructed in geohazards regions, including areas with strong ground shaking, faults, landslides, soil subsidence, differential settlement, or soil liquefaction. Safeguarding pipeline integrity in these areas for unhindered water delivery is an essential requirement of pipeline design. “Geohazards and pipelines” constitutes a major topic in pipeline design, with significant importance on pipeline structural safety. In this paper, state-of-the-art methods for the analysis and design of buried steel water pipelines constructed in seismic and geohazard areas are presented. The main aspects of “strain-based” design for steel water pipe are presented, pinpointing its main differences with traditional “stress-based design,” and expanding on its two components, namely, strain demand and strain resistance (or capacity). The present paper can be used as a reference and a background document in relevant codes and standards.

The development of hazard resilient pipeline infrastructure has drastically evolved in recent years as a growing number of utilities look to improve the resilience of their water distribution systems that can be vulnerable to natural hazards. Pipelines are susceptible to damage from ground movements, such as fault ruptures, landslides, liquefaction-induced lateral spreading, and other large seismically-induced ground deformations. As municipalities and design engineers consider improved materials and jointing mechanisms, there is a need for the performance of these systems to be assessed through full-scale seismic testing. Although experimental testing has been conducted to evaluate the performance of pipeline response to some seismically representative loading conditions, many current methods deconstruct the soil–pipeline interactions into principally oriented mechanical responses. The loading mechanisms considered are limited to movement parallel and perpendicular to the pipeline axis (i.e., axial tension, axial compression, and transverse bending) and do not consider the effects of combined loading that occurs when the ground movement orientation is not aligned with an orthogonal plane of the pipeline. To better understand how combinations of loading affect a pipeline’s seismic performance, a biaxial testing procedure has been developed. This paper reports on a series of six full-scale pipeline tests performed at the University of Colorado Boulder’s Center for Infrastructure, Energy, and Space Testing laboratory. Experiments were performed on 6-in. (150-mm) diameter thermoplastic pipe (DR14) with an internal restraining gasket resisting pull-out of the bell-and-spigot joint. The results of this study illustrate how the transverse ground displacements and local effective system curvature affect the resulting axial capacity. These tests are intended to provide a framework for how a system may be assessed for seismic performance under combined biaxial loading. The presented procedures provide guidance relative to an ongoing ASCE/UESI committee on the Seismic Testing and Evaluation of Pipeline Systems (STEPS) as well as for seismically classifying axial response for the developing ASCE/UESI Manual of Practice (MOP) on Seismic Design of Water and Wastewater Pipelines.

This paper presents a case study of how Austin Water (AW) seized the opportunity to overhaul the Austin, Texas, wastewater system along a densely urbanized corridor in a fast-growing city. The catalyst for this project was the Interstate Highway 35 (I-35) project by Texas Department of Transportation (TxDOT). The roadway improvements include depressed main lanes, significant retaining walls, and limited right-of-way (ROW). While the limitations of the roadway project are difficult for all utilities, they are particularly constraining for the existing gravity sewer system. The project team evaluated alignments, redefined sewershed boundaries, and developed a strategic plan to meet the current and future needs under two different design conditions. The paper discusses how the project strengthened the infrastructure, prepared for population growth by allowing redevelopment along the corridor, and addressed the challenges and opportunities of wastewater design in the context of a highway utility relocation project.

This paper discusses how the designer and owner addressed operational and maintenance challenges of a sewer system built over 32 years ago. The existing 16,000 linear feet (LF) of 27-in. reinforced concrete pipe (RCP) interceptor sewer has experienced collapses due to hydrogen sulfide corrosion. Preliminary engineering included condition assessment, hydraulic analysis, and cost–benefit alternative analysis. Replacement of the interceptor includes a segment of the pipeline that crosses a tributary to the Red Oak Creek. The existing crossing at this location is an encased aerial system with supporting piers on both ends. Design of a new tributary aerial crossing revealed that an encased 48-in. carrier pipe would backup stormwater flow in the tributary channel because of a new lower flow line, which would require a new, long easement for grading upstream. An alternative to the aerial crossing would be a siphon design that traditionally would use concrete structures on either end. Due to the owner’s operational and maintenance challenges associated with concrete siphon structures, an alternate solution to a traditional siphon design was developed in the form of a siphon with FRP wye manifolds.

Among different components of the US highways and roads, concrete pipes are one of the most important parts of these infrastructure. Currently, most of the concrete pipes that are produced in the US are made from steel-reinforced concrete composite, and this system is prone to deterioration and steel corrosion during the service life of these pipelines. In this study, a newly developed synthetic fiber-reinforced concrete composite was studied to determine its chemical resistance in highly acidic environments with accelerated aging methods. Actual reinforced concrete pipes with 0.54% fiber volume fractions were immersed in low pH solutions and elevated temperatures. The D-load test results showed that specimens that were immersed in pH2 solutions lost their ultimate D-load capacity by 20% after 1 year, and pH4 specimens showed an 18% load decrease at the same time. Furthermore, by using SEM and EDX analysis, the chemical composition of specimens that were extracted from these pipes was analyzed. The results showed that at the early stages of the immersion tests, the surface of the pipes in pH4 solution did not absorb a significant amount of sulfur, and it shows that these specimens have not deteriorated significantly. With longer immersion duration, the amount of sulfur element on the surface of the specimens increased gradually, and for pH2, the surface was mostly saturated after 5 months of immersion. For pH4, this value was constantly increasing, and similar to the mechanical tests, pH4 results were converging to the same value of pH2 results. The findings of this research would pave the road to determine the service life of this composite in highly corrosive acidic environments.

Hydrostatic thrust in Bar-Wrapped Concrete Cylinder Pipe (BRCCP) pipelines is usually resisted by field welding a sufficient number of adjacent pipe joints. Three commonly used welded joint configurations are: the gasketed external field-welded joint with a filler bar placed in the field; internal field-welded joint with the gasket groove kept intact; and internal field-welded joint with the grooved end of the spigot cutoff at the manufacturing plant will be illustrated. In 1962, a total of 36 tests were conducted at Ameron’s South Gate Plant on 21 different joint configurations using 1-1/2-in.-wide welded test specimens and four joint configurations were also tested as full ring test assemblies. In 1989, a total of 30 tests on 8 joint configurations were conducted at Ameron’s Engineering Experimental Center in South Gate, CA, using 1-1/2-in.-wide welded test specimens and five configurations were also tested as full ring test assemblies. Description of the 1989 tests and results will be presented. The 1962 and 1989 tests and earlier field observations were the basis for establishing the BWCCP welded joint design criteria given in Ameron’s Design Manual 303, Chapter 9. The 1989 tests performed are described and results presented along with overall summary and recommendations.

The water surface elevation (WSEL) of the existing Highline Canal is approximately 20 ft above the WSEL of the existing San Tan Canal (STC), where the reclaimed water from the City of Mesa would be discharged, necessitating the design and construction of a low-head gravity pipeline of varying diameters. The alignment of the gravity pipeline crosses a spur of the Union Pacific Railroad (UPRR) and Arizona State Highway 87. Near this crossing is a 350-ft segment of abandoned 24-in. C-76 concrete gravity pipeline housed in a steel casing and hydraulic modeling suggested that incorporating this abandoned pipeline into the alignment of the proposed low-head gravity pipeline was feasible. Unfortunately, the existing pipe condition is structurally inadequate. Repurpose the existing C-76 gravity pipeline and manholes with a Sprayed-in-Place pipe (SIPP) liner saved months, or years, of schedule delays, and upwards of a million dollars in permitting and construction of a new trenchless crossing.

The San Francisco Public Utilities Commission (SFPUC) initiated the design and construction of a 250 MGD all-weather headworks to improve wastewater treatment reliability and infrastructure flexibility in San Francisco, California. A critical objective of the project was rerouting the system’s 72-in. channel force main (CFM) to feed the new headworks using a three-story steel moment frame structure. Carollo Engineers, Inc. evaluated several alternatives and recommended a custom-built Victaulic dynamic movement joint (DMJ) to relieve stresses on the pipeline and its supporting structures. This innovative approach helped to accommodate differential movement between the pipe rack and rigid concrete structures without significant damage to piping or supporting structures.

City of Fort Worth’s Clear Fork Lift Station and Force Main project will eliminate regular sanitary sewer overflows in the City’s Clear Fork basin by skimming wastewater from two existing 48-in. interceptors and pumping up to 22 MGD of peak wet-weather flows downstream avoiding existing gravity system choke points. The force main consists of approximately 14,000 linear ft of 36-in. HDPE and traverses multiple interstate highways, rail crossings, the Clear Fork Trinity River, and the City’s premier Trinity Park via multiple installation methods (open cut, hand tunneling, and horizontal directional drill). The primary focus of this paper will be the unique and challenging system hydraulics inherent in designing a system to pump downhill. The discussion will include design considerations related to pump selection, head/flow conditions, and air/vacuum valve challenges. The paper will also include narrative of the project’s history and design alternatives. Construction was substantially complete in the Spring of 2024.

Current hydraulic fracture models to estimate the maximum allowable annular drilling fluid pressure (formation limit pressure) before hydrofracture or blowout will occur during horizontal directional drilling (HDD) operations are largely based on cavity expansion theory. The most common of the models employed in the HDD industry is the Delft equation, which was developed by Luger and Hergarden. However, since then, numerous methods have been proposed which produce a wide range of potential maximum annular pressures that should be applied in design. This paper explores some of the more common formation limit pressure models and identifies which model appears to better predict the actual maximum formation limit pressure based on downhole annular pressure data collected in HDD pilot hole operations in cohesive soils where we observed inadvertent returns (IR) of drilling fluid. Based on the analysis and data comparison presented in this paper, it was concluded that the cavity expansion theory for undrained soils and the Queen’s model provide realistic predictions of formation limit pressures in clays.

Stantec is working with the Region of Peel on the design of the Lakeshore Road Trunk Sewer to divert flows from GE Booth Water Resource Recovery Facility (WRRF) to the Clarkson WRRF. The sewer will be constructed from Jack Darling Memorial Park approximately 3.3 km, then crossing the Credit River and continuing an additional 1 km to Elmwood Avenue. Understanding the geology at this important crossing location is key in the design and construction of the project, driving the depth of the tunnel and appurtenances. Initial desktop geotechnical information and historic field investigations in the vicinity of the crossing indicated that there was a risk that the subsurface bedrock valley was deeper under and east of the river than to the west, extending under the east riverbank and adjacent public library resulting in mixed face tunneling at the originally planned elevation. Stantec undertook a comprehensive geotechnical field investigation followed by an evaluation of mixed face tunneling vs. deepening the sewer, so that it would remain in rock. The evaluation concluded that deepening the sewer had the most benefit to the Region from an overall construction, cost, and operations viewpoint.

Microtunneling is an underground method of constructing pipelines using a remotely controlled, laser guided, steerable boring machine to install a pipe or casing, commonly a reinforced concrete pipe, using pipe jacking techniques. Planning considerations, design, and execution of two-pass microtunnel crossings must account for the limitations, capabilities, and operating loads of both, the casing pipe and the carrier pipe to result in a cost-effective design that minimizes costs and construction risks. The paper will describe five recently completed two-pass tunnels for high pressure pipelines, ranging in length from ~120 m to several kilometers, completed as part of the Transmountain Expansion Pipeline in a wide range of geological and hydrogeological conditions while crossing critical infrastructure networks and environmentally sensitive areas.

The Inglewood Sanitary Trunk (IST) was designed to offload wastewater from the Inner City Trunk (ICT) and the West Memorial (WM) trunks, and convey these flows to the Bonnybrook Waste Water Treatment Plant (BBWWTP), servicing the west and northwest areas of the City of Calgary. This offload allows for the existing 15th Avenue trunks to provide additional sanitary capacity to the north portion of the City. Overall, the system provides service to a total equivalent population of 1.1 million residents and will support growth to the 2,076 design horizon. Phase 1 of the trunk was completed in 2020, intercepting the ICT south of the Bow River. Phase 2 has been tendered and is in the early phases of construction. It consists of a twin 1,500 mm by 400 m long siphon crossing of the Bow River, intercepting the West Memorial trunks on the north side of the Bow River. There were many unique design challenges and considerations on this phase of the project. Complex hydraulic considerations were reviewed in order to maintain serviceability of the siphon through its 50 plus year development life. Complicated flow control and bypass strategies were developed to ensure constructability. This included reviewing and developing connection phasing of intercepting two existing 1,200 mm and 1,950 mm trunks which are located under a major arterial roadway, adjacent to LRT, including detour design. Connection to the existing IST Phase 1 utilizing a purpose-built flow diversion and TBM retrieval shaft in a sensitive residential neighborhood. Workspaces needed to be developed in sensitive parklands. Construction utilizing microtunneling was selected to deal with the challenging geological conditions, which were located through an environmentally sensitive river environment. This paper will explore design challenges encountered in the completion of this important wastewater conveyance project.

The purpose of the Southern Nevada Authority’s (SNWA) Horizon Lateral Program (HL Program) is to improve the reliability and operational flexibility of water delivery in the southern portion of the Las Vegas Valley for existing customers and ensure capacity to accommodate projected water needs. After navigating through the feasibility study and preliminary design phases of the Program, several key variables shifted, and a new set of driving factors emerged. The SNWA initiated a sensitivity analysis to evaluate how the changes impact the planning of the Program. The key drivers assessed were lower projected water demands, inflation, and creative water transfer solutions. A cooperative effort with local purveyors during the sensitivity analysis helped confirm and assess updated water demands and their impact on the Program. Additionally, the impacts of inflation on projected construction costs were assessed and solutions were developed to mitigate cash flow risks. Finally, the sensitivity analysis considered ways to optimize the existing system by potentially transferring water from one service area to another.

McPherson, Kansas, is currently utilizing more water from its main source, the Equus Bed aquifer, than is sustainable long term. This deficit will accelerate depletion of the aquifer as droughts become more intense and longer lasting. Due to its industrial growth over the years, McPherson continues to be a driver of employment in the region, but with this comes an imminent demand for more critical resources. To address this, McPherson’s Board of Public Utilities (BPU) took a proactive approach to ensure water access by promoting conservation and proper management of resources to its residents and industrial customers. BPU also secured water rights south of the city to access groundwater from a more sustainable location of the Equus Bed aquifer. The South Well Field Project (SWF project) provided this sustainable, long-term solution to McPherson for additional population growth, economic expansion, resiliency to drought, and conservation of essential resources.

Due to a need for additional water supply compounded by urban growth and record droughts in Texas, many utilities are looking to supplement their water supplies by building new reservoirs or undertaking other large and expensive water supply projects. As an alternative source of raw water, Tarrant Regional Water District (TRWD) is using constructed wetlands to defer construction of new reservoirs. TRWD is designing and permitting the new Cedar Creek Wetlands. The purpose of the project is to withdraw water from the Trinity River, pass it through a wetland system for natural treatment, and then pump the polished water into the Cedar Creek Reservoir. This will increase TRWD’s water supply, especially during periods of drought, at a lower cost. This paper will discuss three main topics: the purpose and benefit of constructed wetlands, including TRWD’s experience using their George W. Shannon Wetlands located at Richland Chambers Reservoir; TRWD’s efforts and lessons learned over the past 10 years in planning for the project; and technical considerations for moving water through the wetlands system. This will be the first paper on this project and future papers will focus on the design and construction of large diameter pipelines and facilities. Wetlands improve water quality, control erosion, and enhance stream flows while providing habitat for diverse species and offering recreational opportunities. The constructed wetland projects discussed in this paper utilize these natural processes to treat effluent dominated river water while providing a dependable water supply for TRWD’s customers. They have proven to be more cost effective and yield a net environmental benefit when compared to the construction of large surface water reservoirs. In 2013, TRWD proceeded with a 30% design of the Cedar Creek Wetlands system, to allow TRWD to secure the property needed for the project. Early planning resulted in substantial cost savings for TRWD for land and easements. The Cedar Creek Wetlands system has a design capacity of 175,000 acre-feet per year, and consists of a raw water intake and river pump station that sends flow through two miles of parallel 78-in. and 48-in. pipelines to 2,550 wetted acres of treatment wetland cells, a finished water intake and pump station that sends flow through a 10-mi long, 90-in. pipeline to a two-cell balancing reservoir, energy dissipation structure, and outfall to the Cedar Creek Reservoir. This paper will also examine TRWD’s primary technical considerations for moving water through each component of the wetlands system.