Pipelines 2021: Design

El Paso Water (EPWater) is utilizing an alternative delivery approach to replace an approximately 7,000 linear ft-long section of dual 30- and 36-in. diameter wastewater force mains with a fully restrained 36-in. diameter fiberglass reinforced pipe (FRP) under an emergency declaration following a March 2020 overflow. EPWater has contracted with Oscar Renda Contracting (ORC) and hired Jacobs Engineering Group Inc. (Jacobs) as owner’s consulting engineer and construction manager, while staff at EPWater and Brierley Associates Corporation (Brierley) are the Engineers of Record. Given the emergency nature of the project, the alternative delivery model allowed for timely preconstruction engineering and significant rights-of-way versus easement versus existing utilities issues resolutions, for route determination as well as early determinations on materials of pipeline and appurtenances construction/operation. Finally, this paper will describe how the contractor-led alternative delivery provided best value to the owner and community.

Environmental impact assessment is a scientific method for analyzing the environmental impacts associated with the life cycle of a product. The information about the raw materials, processes, and product manufacturing are evaluated to obtain the associated emissions and other ecological impacts. Trenchless cured-in-place pipe (CIPP) renewal method involves a liquid thermoset resin saturated material that is inserted into the existing pipeline by hydrostatic or air inversion, or by mechanically pulling-in, and inflating. The liner material is CIP using hot water, steam, or light cured using ultraviolet light resulting in the CIPP product. The objective of this paper is to evaluate the environmental impacts of CIPP renewal method for sanitary sewers and to identify influencing factors impacting environment. The environmental impact assessment was carried out with the help of SimaPro software using Tool for Reduction and Assessment of Chemicals and Other Environmental Impacts (TRACI) method. TRACI has factors for normalization to allow for comparison between impact categories, which divides the calculated outputs for the individual impact categories by the averaged impact values for each impact category. Results show that the CIPP liner, felt, and resin contribute significantly to the environmental impacts of CIPP renewal. It can be concluded that environmental impact assessment of CIPP renewal method is a vital element when considering sustainable infrastructural development. This study can be useful for analyzing the environmental impacts and associated costs of CIPP renewal for sanitary sewers with different project and site conditions.

Denver’s Metro Wastewater Reclamation District (Metro District or District) initiated the second creek interceptor (SD interceptor) project to provide a regional gravity solution to wastewater conveyance in the northeastern portion of the District’s service area. The project includes the design and construction of a 36-in. to 60-in. diameter, 17.5-mi long gravity sewer, including 14 trenchless crossings. This case study will demonstrate how using the construction management at risk (CMAR) project delivery model and continuous collaboration between owner, engineer, and contractor mitigated project risks, streamlined permitting approvals, and optimized project costs. During the preliminary design phase, HDR evaluated multiple project delivery models for the project against the project goals and requirements. Through a qualification based, competitive selection process, the District selected Garney Construction as the project CMAR Contractor at approximately 30% design milestone. Active CMAR contractor participation in the design team’s pursuit of project permits and ROW streamlined the process without unknowingly burdening construction with onerous construction constraints.

Stakeholder involvement in large linear infrastructure projects under public–private partnership (P3) usually is one of the main risk contributors in terms of cost overruns and schedule slippages. Utilities are not the exception, and their involvement from the early stages of the project is crucial for the project success. In order to clearly setting rules, a utility responsibility matrix should be conceived since the planning stages of these P3 projects, even before project award. The responsibility matrix not only determines who does what in terms of design but also during construction. Some utility agencies are more conservative and prefer to have both the design and construction done by the Utility Agency or its contractors, while others are open to transfer that risk to the Project Co. There are other cases, in between these two, where the Utilities provide a list of their preferred or approved contractors and consultants, being managed by the Project Co. Construction or Design Joint Venture. However, the fact of having the rules set often creates other challenges that affect the design process and hence impacting the overall schedule, adding more complexities on the Utility Coordination task. This paper will explore and explain these complexities in detail based on a large Light Rail Train Project in Canada and will seek for opportunities to improve this process, sometimes overlooked by the stakeholders involved [Utility Companies, Project Owner/Technical Advisor, Project Co. (Construction and Designer Joint Venture), Approved Sub Consultants, among others].

CANDE and AASHTO pipe design documents inappropriately group soil types that have greatly varying strength and compressibility properties leading to unnecessary design uncertainty. Most notably, fine-grained elastic silt (MH) is grouped with coarse-grained clayey gravel (GC). There are other groupings that also do not seem appropriate. A defensible design of buried pipe requires acceptable limits on uncertainty. The CANDE and AASHTO groups exhibit an unjustifiably broad range of soil behavior and therefore may often not result in designs of acceptable uncertainty. Additionally, the CANDE and AASHTO naming convention causes problems in referring to the soil groups by using redundant symbols. The inappropriate grouping of some of the soil classifications will be illustrated by comparing their engineering properties. An alternate grouping is proposed.

One of the fundamental goals of utilities project management is increasing the efficiency of using resources and reducing waste. Enhancing resources utilization in linear construction projects can be achieved by levelling the project resource and/or reducing the required number of resources to accomplish the project. This might enable construction planners to address problem of resources limitations and avoid the additional costs incurred due to the poor resource management. Accordingly, this paper presents the development of a new single-objective optimization model for scheduling linear construction projects based on the line of balance technique that minimizes the required number of the needed resource for the project while maintaining the project duration. The optimal generated schedule of the developed model identifies optimal start time and optimal number of construction crews of each activity. To simplify the application of the developed methodology, a computerized model is created by optimization tool “GANetXL” in Excel. A case study adopted from the literature is analyzed to validate the developed model and to illustrate its capabilities compared to the existing ones.

Surprising value is reaped for pipeline projects utilizing (1) advanced geophysical investigative tools and engineering tactics applied in accordance with standards and practices promoted by the American Society of Civil Engineers (ASCE) Utility Engineering and Survey Institute (UESI) and (2) emerging technologies for managing data and developing 3D models for visualizing and design. This case study covers the process used and demonstrates the remarkable benefits achieved through ASCE compliant utility data acquisition including advanced geophysical investigative methods, 3D CADD modeling and design, and conflict analytics with existing infrastructure (including abandoned, unknown facilities) coupled with a sensitivity analysis to assess and optimize alternative pipeline alignments in 3D. Benefits achieved included expedited permit approval with waivers; greatly enhanced bidding; expedited construction executed with half the scheduled work force and completed in 30% less time without change orders, damages, or delays.

The American Society of Civil Engineers (ASCE) Task Committee on Thrust Restraint Design of Buried Pipelines (Task Committee) is currently developing a Manual of Practice (MOP) on the subject under the Pipeline Division of the Utility Engineering and Surveying Institute (UESI). This MOP, currently in its final stages of development, proposes a unified method that can be applied to all common pipe materials used in the water and wastewater industry. This proposed unified approach utilizes advanced soil-structure interaction concepts and consistent soil and pipe-soil interface parameters to better model the conditions of a buried pipeline subject to thrust forces. The proposed framework consists of two distinct design solutions: (1) continuous (welded, fused, or flanged) pipelines and (2) segmented pipelines (those with some degree of joint flexibility to allow angular deflection and axial slack) to accommodate the different types of joint types used in practice. Analytical models based on beam on elastic foundation (BOEF) theory were developed to evaluate restrained joint design for each pipeline type. The segmented model incorporates individual beam segments connected by nodes that represent the joints. Each node has six equations in six unknowns; therefore, advanced numerical computational methods are used to obtain the solution. On the other hand, the continuous model is a special case of the segmented model and results in a quadratic equation that can be solved without advanced numerical computational methods. The continuous model from the unified framework is applicable for continuous pipelines. Compared to the segmented model, this approach is simpler; however, it should be recognized that this method is significantly different from the current practice as it incorporates slightly different pipe-soil interaction concepts, assumptions, and most importantly different, yet more appropriate soil parameters consistent with general geotechnical engineering practice. Therefore, the task committee undertook a comparison of the restrained length results from the new approach and the current practice to understand the impact of the new approach and explain any differences observed. Due to space limitations, only the thrust restraint analyses and results pertaining to welded steel pipe, which is a continuous pipe, will be presented in this paper. The results obtained from the new approach will be compared with the results obtained using the current thrust restraint design approach contained in the AWWA design manual M11 for steel pipe.

The American Society of Civil Engineers (ASCE) Task Committee on Thrust Restraint Design of Buried Pipelines is currently developing a Manual of Practice (MOP) on the subject under the Pipeline Division of the Utility Engineering and Surveying Institute (UESI). This MOP, currently in its final stages of development, proposes a unified method that can be applied to all common pipe materials used in the water and wastewater industry. This proposed unified approach utilizes advanced soil-structure interaction concepts and consistent soil and pipe-soil interface parameters to better model the conditions of a buried pipeline subjected to thrust forces. The proposed framework consisted of two distinct design solutions: (1) continuous (welded, fused, or flanged) pipelines and (2) segmented pipelines (those with some degree of joint flexibility to allow angular deflection and axial slack) to accommodate the different types of joint types used in practice. Analytical models based on beam on elastic foundation (BOEF) theory were developed to evaluate restrained joint design for each pipeline type. The segmented model incorporates individual beam segments connected by nodes that represent the joints. Each node has six equations in six unknowns; therefore, advanced numerical computational methods are used to obtain the solution. On the other hand, the continuous model is a special case of the segmented model and results in a quadratic equation that can be solved without advanced numerical computational methods. Based on the work completed to-date, the task committee concluded that it would be appropriate and reasonable to solve the segmented pipeline problem as a continuous pipeline to obtain conservative, yet economical restrained lengths for buried pressure pipelines. In order to validate this conclusion, several different problems were analyzed using the numerical models developed for segmented pipelines using both segmented and continuous models, and the results were compared. Due to space limitations, only limited number of thrust restraint analyses and results pertaining to ductile iron pipe, which is a segmented pipe, are presented in this paper. In addition, this paper compares the results obtained from the segmented model with the results obtained using the current thrust restraint design approach contained in the Ductile Iron Pipe Research Association (DIPRA) design guidelines and AWWA design manual M41 for ductile iron pipe.

In 2017, the City of Houston performed a condition assessment of an existing 96-in. water line in preparation for widening of Clinton Drive by TXDOT. Lockwood, Andrews & Newnam Inc. (LAN) was selected to perform the condition assessment that included installation of two temporary bag stops, three 96-in. butterfly valves, and select appurtenances, as well as performing electromagnetic testing, cathodic protection assessments, and internal inspections.Then in 2020, a pipe segment along this transmission line failed catastrophically impacting a large portion of the City. Contractors were mobilized and the repair process started almost instantly. Not long after the line was repaired, and back in-service LAN performed additional testing and a forensic study on the segment that failed and two adjacent segments that were removed. This paper will present the work performed and discuss the conclusions of the study at the end the process. Discussions will include nondestructive testing performed, destructive testing performed, and materials testing that were performed.

Subsurface infrastructure supports modern cities’ sustainable functionality in terms of services such as gas, electricity, clean water, and sewer. However, damages to subsurface infrastructure are a significant challenge during construction. As a result, damage prevention techniques have received special attention in recent years. The current infrastructure damage prevention techniques in the United States can be categorized as follows: (1) one call system and (2) subsurface utility engineering (SUE). This study illustrates the main differences between them and demonstrates which approach should be utilized based on the project field conditions and the project needs. Finally, the study discusses the constraints that may prevent smaller construction firms from using SUE. As a result, the study serves as a quick reference for construction practitioners to better understand their options for reducing damages to underground utilities during construction.

Everyone is interested in “quality” on their pipeline project. But what is “quality”? How can it be incorporated into large diameter pipeline projects? A review of seven years of pipeline projects has resulted in common overlooked and misunderstood items in design and construction, which may be arrested and reduced with the incorporation of quality management procedures. Methods of quality management incorporation are discussed, which include top-to-bottom organization quality (management) as well as bottom-to-top organization quality (execution). Inexperience of design/construction personnel is also discussed, with suggestions provided as how to maintain standards while concurrently introducing quality management concepts to a new generation. Also, the concepts of “pre-project,” “project,” and “post-project” quality management are investigated. Finally, common barriers to incorporation of quality management are reviewed along with some suggestions for their mollification.

The formal quality assurance/quality control (QA/QC) review phases of a pipeline design project are important steps in ensuring a high-quality product that mitigates the risk of issues during construction and operation of the pipeline system. The review phases should be planned as part of the project initiation. This paper includes several practical suggestions for the reviewers and the reviewees to improve the quality assurance and quality control process for water/wastewater conveyance projects involving drawings and specifications. This paper is divided into five parts. They are (1) Introduction—provides general information and suggestions for planning and executing the quality assurance phase of the review process, (2) Suggestions for the Reviewee—whose work is being checked, (3) Suggestions for the Reviewer—who is performing the quality control, (4) List of Topics—that should be considered or may be overlooked in the review, and (5) Summary—the important items are discussed.

A proposed 84-in. steel water line intersects the active normal dip-slip Woodgate Fault, of which the estimated vertical movement rate is approximately half inch per year with a down-to-the-coast dip angle of 77°. This surface water transmission main is owned by the North Harris County Regional Water Authority (NHCRWA) which comprises 335 square miles and includes approximately 710,000 residents. The anticipated vertical and horizontal movements within the design lifespan pose a significant risk to the water line since local buckling may occur due to excessive ground movement. Other challenges, such as (1) constraint of right of way (ROW), (2) balancing cost and reliability, and (3) accessibility for operation and maintenance (O&M), further complicate the design. To meet all design requirements, multiple design alternatives were evaluated, and an optimized “design and maintain” approach was selected. The design concept is verified and refined by finite element analysis (FEA) using a nonlinear Winkler-based soil spring model. It is found that the proposed O&M guidelines can reduce the risk of the water line by limiting the compressive strain induced in the steel carrier pipe, hence preventing local buckling. Also, the proposed approach reduces the overall construction cost while maintaining an acceptable level of reliability, and the O&M is facilitated by providing maximum accessibility to the couplings.

Evaluating welded steel pipe and pipe joint strength for resisting seismic forces is essential for today’s conveyance infrastructure. Minimal guidance is available for seismic design of large diameter, thin wall, spiral-welded steel pipe, causing designers to employ design methods outside the welded steel pipe industry. Application of nonindustry information could lead to unconservative results with questionable seismic resilience. While the effects of internal pressure are known to augment the strength of welded steel pipe in some cases, accurate test data is currently unavailable. This paper describes physical tests to evaluate the strength of welded steel pipe, field-welded joints, and mechanical joints under both pressurized and nonpressurized conditions. Also presented is a discussion of expected test results, compared with codes, and standards for welded steel pipe. The goal is to determine how large diameter steel pipe and common joining methods will perform when subjected to compression, tension, and bending forces.

The limit equilibrium method for evaluating the slope stability only provides a factor of safety against slope failure and offers no insight into the magnitude and distribution of the ground movement. An alternative approach is to design the pipeline to accommodate the anticipated ground displacement. This approach relies on the development of two numerical models. The first model, a 2D, dynamic, and effective stress FLAC model of the slope to estimate the magnitude and distribution of the seismically induced ground deformation. The second model, a 3D pipe-soil interaction finite element model, is used to evaluate the tensile and compressive strain in the pipeline. This paper presents a case study of the use of this approach to design a drinking water pipeline crossing of Beaverton Creek where up to approximately 3 m of seismically induced permanent ground deformation is estimated, resulting from soil liquefaction. The NPS 48, steel, and butt-welded pipeline will be installed via open cut and two trenchless drives. Based on the results of the paired analyses, pipe wall thickness was increased in areas with high strain. The use of expensive and time-consuming ground improvement was deemed unnecessary.

The paper describes the application of a novel and promising concept, aimed at absorbing ground-induced displacements due to soil subsidence in buried steel pipelines entering or exiting concrete or rigid structures. In particular, the use of a patent pending concept of small projections is proposed, appropriately located along the pipeline, at the critical zone of soil subsidence, where deformation of the pipeline is expected. Using this solution, the pipeline is able to deform in a controlled manner such that there is no loss of pressure containment and the pipeline will continue to perform long term. Advanced finite element simulations have been employed to model the projection and characterize its structural behavior. The present concept is applied on an 84-in. diameter buried steel pipeline, and the results indicated that the use of projections at appropriate locations improves structural performance, decreasing both strain in the pipeline wall and the reaction forces and moments at the concrete wall.

Earthquakes disrupt the operation of critical lifelines in a community, such as underground water and gas infrastructure systems. The importance of the seismic vulnerability assessment of water pipe networks cannot be exaggerated as it has a critical role in preventive seismic rehabilitation decision-making performed to avoid costly repairs. Existing seismic vulnerability assessment methods do not consider water pipe network uncertainties (e.g., uncertainties in nodal demand, reservoir head, and pipe roughness coefficient) despite the considerable susceptibility of these assessment methods to these uncertainties. Examining the effect of network uncertainties on post-earthquake serviceability of water pipe networks is the first step towards assessing the vulnerability of water pipe networks under uncertainties. The objective of this research is to investigate the effect of network uncertainties on the post-earthquake serviceability of water networks. Demand and pipe roughness coefficient were the network parameters selected for this study. Design of the experiment, Monte Carlo simulation, and one-way analysis of variance (ANOVA) tests were used to examine the individual and combined effects of two water pipe network uncertainties (nodal demand and pipe roughness coefficient). The approach was tested on the Modena network, which is a city-scale benchmark network that is commonly used in the literature for seismic vulnerability assessment of water pipe networks. The results show that the uncertainty of these two selected network parameters has a statistically significant impact on the post-earthquake serviceability of water pipe networks. Hence, it is recommended to integrate the network uncertainties with the seismic vulnerability assessment of water pipe networks.

This paper describes the structural design of a large-diameter buried steel pipeline crossing two areas of substantial soil settlement, which impose fault-type actions in the pipeline. Those ground-induced deformations are associated with the development of high levels of strain, well beyond the elastic limit of the pipe material. The present paper describes the application of “strain-based” design approach, towards economically efficient solution, while increasing pipeline safety and reducing risk. Strain demand is calculated first, using a global analysis, through finite element models, developed for the purposes of the present design. The numerical models employ “pipe elements” to simulate the pipeline and “soil springs” to describe the soil and its interaction with the pipeline. Subsequently, the ground-induced strains are calculated and compared with the allowable values. The design makes use of a newly developed concept, the “projection” concept, which increases pipeline resilience and improves lap welded joint performance. The effects of soil conditions on pipeline performance are also discussed.

North American bridge design codes recommend a minimum burial depth for culverts to prevent failure during construction or under vehicle loading. The design of flexible culverts, such as those made of corrugated steel plate, has historically focused on circumferential force in the conduit walls (i.e., hoop thrust) as the critical failure mode. However, recent studies have shown that bending stresses are often of the same magnitude as hoop stresses, especially for noncircular pipe culverts with cover depths that are at or near the recommended minimum level. To investigate this issue, an elliptical corrugated steel culvert with span of 1,650 mm, rise of 1,300 mm, and corrugation profile with a 25 mm amplitude and 75 mm wavelength was tested at different cover depths ranging from 0.1 to 1.2 m under simulated vehicle loading. The culvert’s response to live load quantifies just how much more dominant bending moment is than thrust. When combined earth and live loading is considered, moments are still important, and the results quantify the transition from a flexural, live load dominated response at extremely shallow cover depths to a more earth load dominated response at cover depths greater than 500 mm.

Across the United States, a large number of corrugated steel pipes, installed three or four decades ago, are approaching the end of their useful service life. In many cases, these aging drainage structures have significant degrees of metal loss over their inverts due to the conveyance of abrasive surface water thay can be acidic. However, there is not yet any guidance or specification on the design of concrete poured in the culverts with high level of corrosion at invert for rehabilitation. The aim of this study is to use experimental results and finite element (FE) modeling of a culvert under Coopermill Road near Zanesville in Muskingum County, OH, selected for replacement based on its level of corrosion in order to the results to be used to develop a rational design method. The FE model was calibrated and validated with previously published experimental results by the authors. Before replacement, concrete was poured in half of the culvert towards the outlet. The culvert was also simulated using FE modeling with the three-dimensional ABAQUS program. FE model results were in reasonable agreement with experimental measurements. Despite the condition, the culvert supported a load considerably larger than the legal limit of 18 kips. The stresses at the interface of the steel culvert and the poured concrete treatment were not very large. The FE model results were in good agreement with field measurements. This agreement may have been enhanced by the materials undergoing cyclic loading during the culvert’s service life. This preliminary study indicated that the three-dimensional FE model program could be utilized to develop a rational design procedure.

The design of buried culverts and other buried components is typically carried out by static analysis assuming static truck loads. In reality, the culvert is subjected to a combination of static and dynamic loads. The total design load capacity depends on several parameters such as load modifier, load factor, and dynamic load allowance depends on the depth of earth cover above the culverts. However, there is limited information for minimum soil cover (less than or equal to three feet at the crown) to assess a pipe’s dynamic load allowance. The objective of this study is to investigate the performance and dynamic response of a triple circular culvert instrumented and tested under dynamic truckloads with different truck speeds. For the dynamic loading, the truck was driven over the driving lane at four different speeds: 5, 10, 20, and 25 mph. The strains at the five locations of the outside Pipe-1 and the center Pipe 2 and the displacements were recorded at a 1,200 Hz frequency. Due to the symmetry of the pipe construction, only two pipes were instrumented; Pipe-3 might react in a manner similar to Pipe 1. Response to dynamic loads was measured by driving the loaded truck over the culvert at various speeds ranging from 5 mph to 25 mph. Maximum longitudinal and transverse strains were observed in Pipe 2. The maximum longitudinal strain of 1,112 με was observed at sensor 2-3AL during the run at 20 mph run; the maximum transverse strain of 713 με was observed at sensor 2-2AT during the run at 20 mph run. These dynamic results were then used with previously published static experimental results by the authors to calculate the dynamic load allowance. It has been found that the dynamic load allowance obtained was higher than the magnitude recommended by AASHTO LRFD Bridge Design Specification for buried culverts. However, it is recommended that the dynamic load allowance value be investigated further in the buried culverts under shallow cover since these results yielded a higher amplification factor than the one recommended by the AASHTO LRFD.

This paper explores the performance parameters of inverted siphons (also known as depressed sewers) in sewerage and raw water conveyance systems. It focuses on the management of water, air, and sediment transport in two design case studies in the Pacific Northwest. The paper discusses the mechanisms of air/gas and sediment development in conveyance systems, literature review findings, lessons learned from historical installations, the design steps adopted in the case studies, and what can be done to minimize the risks of air and sediment capacity restrictions. A focused understanding of sediment characteristics, mechanisms for development, and how air and sediment behave at critical flow rates will assist in maintaining conveyance capacity through profile development and infrastructure placement and geometry. The design solution for air and sediment transport need to consider the transport impact on both. It is economically impractical to eliminate particle and air retention in inverted siphons, but through appropriate design processes, their behaviors can be better understood and impacts reduced.

The City of Houston (the City) and USEPA have recently entered a consent decree and are working to address a number of sanitary sewer overflows. One of the areas highlighted in this decree involves a periodic overflow within a low-lying area just north of the central business district, located within the historic Houston Heights neighborhood and referred to as the “Wrightwood SSO.” Preliminary evaluation showed that surcharge occurs throughout the entire system during heavy rain events due to limited capacity at the downstream lift station and treatment plant. A wide range of improvement alternatives were available for consideration to improve the existing network related to this single localized overflow requires significant investment to resolve. To evaluate these options, the City of Houston used both traditional “trial-and-error” scenario modeling and intelligent algorithm optimization software to evaluate alternatives and develop low-cost, defensible solutions.

As the water and sewer utility provider for one of the fastest growing counties in the country, the Berkeley County Water and Sanitation continuously updates and modifies their existing infrastructure to ensure reliable water and sewer service. One of its most recent improvements was to the Lower Berkeley Wastewater Treatment Plant through the installation of over 20,000 linear feet (LF) of 18-in. and 14,500 LF of 24-in. fusible polyvinylchloride force main through trenchless installation methodologies.

The Bonnybrook Wastewater Treatment Plant (BBWWTP) is one of the largest cold weather BNR plants in the world undergoing a significant expansion, including a new outfall to discharge all treated effluent into the Bow River. The BBWWTP currently discharges all the treated effluent flow into the Bow River via a conventional bank outfall. The new outfall is not only required for plant expansion but also is an integral part of a flood protection plan for the site. Design of the outfall system was focused to strike a balance between flood protection capabilities, upsize for expected flow increase to year 2076, environmental enhancement, and cost. The outfall is designed to convey 1,962 MLD (22.71 m³/s) (518 MGD) to a new exfiltration style diffuser under the bed of the Bow River. Construction of the new outfall is ongoing and scheduled to be complete by the end of 2021. The presentation will discuss the project drivers and motivations, some of the key design and construction challenges, and contracting strategy used to deliver this infrastructure.

The City of Conroe’s Wastewater Master Plan identified the need to improve the flow to the City’s central treatment plant to mitigate the lack of capacity within the collection system. The primary accomplishments of this sewer design project include the expansion of the Lower Stewart Creek interceptor from 48 to 66 in., the installation of a bifurcated wye at the Valwood Creek crossing, and the removal of the Carl Barton Lift Station. These improvements poise the City to accommodate future growth, minimize future maintenance, and reduce excessive expenses. The main challenge of the project was that the design approach was not ideal for the proposed 66-in. gravity sewer crossing of Valwood Creek. To resolve this issue, a fiberglass bifurcated wye was used in place of a large concrete junction structure. The project is currently under construction and should be at substantial completion phase at the time of this presentation.

Hydraulic transients, also known as SURGE events, are an essential consideration in the design and operation of water transmission and distribution systems. A detailed SURGE analysis may not be required in all circumstances. Several considerations should be evaluated to determine the level of analysis required. We offer the following mnemonic device to assist engineers and owners to determine whether a SURGE analysis is necessary. SURGE—system configuration, utility owner’s requirements, risk management, governing operations strategy, expertise with hydraulic systems. The purpose of the following sections summarizes and identifies important factors related to the need for SURGE analysis. An exhaustive list of flow rate, pressure, pipe material, and more set points and criteria that are required for a SURGE analysis is beyond the scope of this paper due to the multiple (and often interrelated) variables involved.

In design of water distribution systems, the design approach is to satisfy pressure at any point in the system within minimum and maximum acceptable level. Criteria on pressure standards are different around the world. It means that the pressure delivered to a customer might be accepted in some countries, while the same delivered pressure in other countries is considered unacceptable. Researchers agree that high pressure systems tend to cause more frequent pipe breaks and an increase in energy use and leakage. While low pressure systems cause consumer complaints, make the system more susceptible to down surge pressures during transients, and possibly to cause contaminant intrusion in some circumstances. This paper highlights the ambiguity exists on pressure standards and how it affects design and operation of water distribution systems. The relation between water demand and pressure, leakage, energy use, and system operation are discussed. The aim here is to motivate the cities and political jurisdictions to rethink about the pressure standards for water networks design to enhance the performance of water networks systems.

The Region of Halton is experiencing rapid development and growth. Under the Sustainable Halton Water and Wastewater Master Plan, the Trafalgar and Derry Road Feedermains and 30 mL Zone 4 Reservoir Project was developed to provide Halton Region with sustainable growth and servicing strategies to meet the needs of the growing population. The growth requirements in North Halton have identified the need for a future maximum day flow of nearly 9 mL per day with a peak hourly flow over 16 mL per day. This increased future water demands combined with the limitations of sustainable groundwater supply has led to the identification of the need for greater integration of the region-wide water systems. This paper will discuss the approach taken in the design of over 18 km of large diameter feeder mains to minimize operational and maintenance issues, reduce overall capital costs, while providing maximum operational flexibility to maintain water quality objectives under both short-term and long-term project water demands.

The North Harris County Regional Water Authority planned the Project 28 series of water transmission alignments for a second water system loop to provide additional surface water and to meet the 2025 Harris-Galveston Subsidence District conversion mandate. Project 28D is a critical alignment within the Project 28 series located in northwest Houston which consists of 11,300 LF of 60-in. and 400 LF of 84-in. water transmission mains within easements and along drainage channels. Design of this project began earnestly in 2015; however, natural disasters occurred causing regulatory changes that required multiple design adjustments and delayed the completion of the design. New development also occurred along the project alignment which also required changes to the design. How the design team responded to the regulatory changes and proactively worked with property owners of the new developments ensured the project’s future success. Project 28D is now scheduled to begin construction in early 2021.

In most of North America, concrete pressure pipe will perform for many decades without cathodic protection or other supplemental corrosion control mechanisms. There are locations on the continent where supplemental corrosion protection is essential for a concrete pressure pipe project to reach its design life. This paper will review the installation conditions in which concrete pressure pipe does and does not need supplemental protection, as well as present issues and options regarding the corrosion protection alternatives that can be applied.

Plastic pipe designers have to think about the design in two directions, circumferential and longitudinal—and when it settles on the construction site for such loads as gravity, internal pressure, negative pressure, Poisson’s ratio, temperature, and end load. Polyethylene reinforced with short glass fibre called PE-sGF pipe provides improved strength, in comparison to the corresponding thermoplastics material and based on the improved circumferential strength, good chemical resistance, and low weight. PE-sGF pipes and fittings combine the well-known properties of PE100 polyethylene with the significant characteristics of short glass fibres. The inner and outer layer of unfilled PE100 provide a smooth inner bore for fluid flow and an outer surface for fusion bonding. In 2020, PE-sGF discharged pipeline of 1,800DN/ID, approximately 2 km length were completely settled down for coal fired generation plant in Japan. This paper is showing properties, designation, and construction of large diameter PE-sGF pipeline.

Contra Costa Water District (District) has several water sources, including an intake from the San Joaquin River at Rock Slough. Water from this source was originally conveyed to the District’s water treatment plants via 6.5 km of unlined canal with a capacity of 9.9 cubic meters per second (m³/s). The District has been executing a project to convert the canal into a buried 3-m diameter reinforced concrete pipeline (RCP). As of December 2020, four of five segments totaling 4.5 km have been converted to pipe, with approximately 2 km of canal remaining. Changing this system from an open channel gravity system to a closed conduit system required a complete hydraulic redesign of the conveyance system. A hydraulic model was developed to evaluate a wide range of operating scenarios to accommodate both current and future conditions. The hydraulic model identified limitations in the intake system and a path forward for the District to maintain the system’s 9.9 m³/s conveyance capacity.

Current civil engineering practice for water line projects commonly replicates proven design tables and standard details. However, the designer should proceed with caution because there are instances when the use of standard details, or the replication of the details of an existing installation, could cause serious operational and maintenance problems or failure. This paper discusses the necessity to refocus a design approach premised on standard buried pipe details for water line replacement on a pier, supporting important maritime activities, to the actual need to design for a pipe supported on hangers below the pier. Comments discuss the differences in the forces developed in each case, the associated design considerations, and the application of basic engineering principals to address those differences.

Tunnel No. 2 is one of the three tunnels along the Fort Laramie Canal constructed between 1915 and 1924. The tunnel suddenly collapsed in July 2019 and soil from nearly 100 ft of noncohesive formation above the tunnel plugged the tunnel terminating the flow. Failure analyses showed that deteriorated timber forms over time, movement, and internal erosion of fine material resulted in voids forming behind the lining. These voids lead to cracks developing in the lining. Eventually a cracked lining section in the crown collapsed initiating a catastrophic collapse. The lessons learned from this tunnel failure include continue periodic inspection of facilities to maintain a dynamic data-base about infrastructure conditions as well to classify associated risks, migration of fines behind lining alter loading distribution on the lining, causes of cracks and offsets must be examined, and evaluation for repair methods of cracks, offsets, and voids require immediate attention.

The Tarrant Regional Water District (TRWD) operates and maintains over 200-mi (322 km) of raw water pipelines bringing water from east Texas Lakes to the western side of the Dallas Fort Worth Metroplex. Part of this system includes approximately 50 mi (80.5 km) of two parallel prestressed concrete cylinder pipelines (PCCP) located in a 130-ft (39.6 m) right-of-way between the Rolling Hills Water Treatment Plant in Fort Worth, TX, and the Ennis Booster Pump Station east of Ennis, TX. The older of the two pipelines is the 72-in. (182.9 cm) Cedar Creek PCCP constructed in the 1970s. The second pipeline is the 90-in. (228.6 cm) Richland Chambers PCCP constructed in the 1980s. Over the years, the Cedar Creek pipeline has experienced approximately 20 pipeline failures, and the increased risk profile for this pipeline has led TRWD to consider a larger pipeline replacement program. Based on system growth and improvements, TRWD now has the operational flexibility to take the Cedar Creek pipeline out of service for an extended period of time to tackle a larger pipeline replacement program. In 2019, Black & Veatch was selected to perform engineering services for the replacement of approximately 10 mi (16.1 km) of the Cedar Creek pipeline located in the cities of Mansfield, Grand Prairie, and Midlothian, TX. One stretch of the project crosses the headwaters of Joe Pool Lake in Grand Prairie, TX. This area includes the crossings of Mountain Creek and Soap Creek. Since these pipelines were installed in the 1970s and 1980s, the widths of the creeks have increased due to erosion, and scour has occurred at the flowline of the creeks. This project includes an evaluation of the best method for the pipeline crossing of these creeks as well as a long-term solution for maintenance access across them. The goal of this project is to provide a sustainable pipeline system that reduces the overall risk of system failure while also meeting the needs of future water demands and maintenance access. This paper will provide a brief overview of the need for the 10 mi (16.1 km) pipeline replacement project, discuss the challenges for crossing a mile-long floodplain, and summarize recommendations for the crossings of Mountain Creek and Soap Creek for both the pipeline installation and long-term maintenance access.

After a catastrophic failure on the City of Houston’s North 60 (N60) water transmission line that disrupted service to a million customers in the Greater Houston Area in 2001, the City has taken a proactive approach to prevent further disruption. Though others have occurred while an alternative source has been identified, none have had the same impact as the failure in 2001. Over the last 10 years, an alternate source was identified to provide redundancy to the system through designing and constructing a 72-, 66-, and 60-in. waterline (Contract 70) to bring additional water from Houston’s Southeast Water Purification Plant (SEWPP) service area into the area supplied by Houston’s East Water Purification Plant (EWPP).Contract 70 included evaluating and installing approximately 44,700 linear feet of 72-, 66-, and 60-in. waterline through multiple contracts that included passing Houston’s Hobby Airport, multiple fault crossings, United States Army Corps of Engineer’s (USACE) water crossing, major thoroughfare crossings and will provide take points to multiple smaller pump stations and authorities in the area. Several unique issues had to be accounted for during the multiple segment designs that included shoring and shutdown sequencing to minimize impact when connecting to the existing 96-in. waterline along Fuqua;improvements including a new metering station and roof replacements at a key repump station required prior to full installation of Contract 70; working next to Houston’s Hobby Airport and coordinating with the FAA for determination of No Hazard to air navigation for temporary structures; and multiple large diameter tunnels totaling 3,000 LF and also included a crossing of USACE maintained Sims Bayou and tie-in to existing 60-in. PCCP waterline. With the last segment of the transmission line nearing completion, the waterline will be completed allowing further preventive maintenance needs to be addressed along two critical 60-in. waterlines, installed in the 1960s, and the entire Contract 70 waterline to be placed into service.

High density polyethylene (HDPE) piping has been around since the late 1950s; however, it was not until the 1990s that its use became more widespread in large diameter pipes for municipal water and sewer applications. As its usage has become more common practice, coupled with improvements in the technology, the more recent resins (the building block of HDPE pipe) being produced have created a HDPE pipe product with thinner walls of a certain pressure rating than the previous resin types. In addition, newer technologies in the production process can now produce overall thicker wall HDPE pipe. These two advancements, the strength of the underlying resin and the ability to make overall thicker wall HDPE pipe during the extrusion process, now permit the industry to produce even larger diameter HDPE pipes at higher pressure rating classes that were previously unavailable.

Connections to existing concrete pressure pipes frequently require unanticipated design solutions. Each of the steel cylinder concrete pressure pipe materials present unique challenges when making connections, especially when the existing pipe is old, the original pipe manufacturer is long out of business, and the owner has no records. Common connections made to existing concrete pressure pipes include taps for outlets, removal and replacement of select pipe segments for outlets, in situ modification of pipe for outlets, and in-line or end connections for pipeline relocations. This paper addresses some of the more commonly encountered but unique challenges for in-service or pressurized (“hot” or “wet”) taps of concrete pressure pipelines, and “dry” connections (where the connecting pipeline can be depressurized and dewatered for a short time). Changing the thrust restraint regime for the existing pipeline and maintenance of or restoration of bedding and backfill of the existing concrete pressure pipelines are also addressed.

The City of Houston’s (City’s) Northeast Water Purification Plant (NEWPP) supplies an 84-in. steel transmission line that serves the northern Houston area along with several water authorities. This pipeline has existing interconnections to multiple Municipal Utility Districts and includes an 84-in. stub out for a future transmission line interconnection. The City is expanding their NEWPP and constructing a new transmission line which ranges from 120-in. to 54-in. but consists mostly of 108-in. transmission line. This line is called the Northeast Transmission Line (NETL) and will help the City to meet the future growth in demand. One segment of the NETL consists of a 108-in. by 84-in. interconnection with gate valve to an existing 84-in. stub out. With limited space, an innovative solution was required for both the design and construction of the interconnect.

The Luce Bayou Interbasin Transfer Project (LBITP) was commissioned by the Coastal Water Authority (CWA) as a regional water supply project to convey water from the Trinity River to Lake Houston. The LBITP consists of a raw water intake structure and pump station, approximately 3 mi of dual 96-in. diameter transmission pipeline, pig retrieval station, flow distribution basin, sedimentation basin, and approximately 24 mi of canal. The pig retrieval station consists of an underground vault housing expanded pipe sections to install steel cables for stopping the pipe cleaning pig valves and decant line. The vault is covered by a metal building with removable sections to facilitate access. Downstream of the vault, a concrete wye structure serves two purposes: It contains grooves for stop logs to stop the pig once it exits the vault and provides open access for pig retrieval. It centers the flow of water and sediment entering the flow distribution basin. Design considerations included vault covering with a removable building, a Victaulic coupling system, a pig stopping system, and a flow distribution system design confirmed with computational fluid dynamic (CFD) modeling. The purpose of this paper is to discuss the constructability of the pigging retrieval station that allowed for a reduction of footprint, ease of construction, and differential settlement solutions.

A discussion of approach to design a large diameter water transmission line in Central Texas, allowing three different pipe materials at two pipe diameter alternates, providing flexibility and the ultimate final product for the owner. Discussion will include approach to design calculations and analysis, preparing drawings, structuring contract documents, and navigating the ongoing COVID-19 pandemic.

In order to keep up with demand, San Patricio Municipal Water District (SPMWD) evaluated options ranging from increasing treatment capacity to purchasing additional treated water directly from the City of Corpus Christi. After discussions with industrial customers regarding required water quality and quantity, it was decided the way forward was to supplement its existing treated water capacity with additional purchase water from the City of Corpus Christi. This would require a new 48 in. water transmission pipeline extended approximately 23 mi from Corpus Christi to Gregory, TX. As the consulting engineer, J. Schwarz & Associates was asked to design this pipeline with four different pipe materials in mind: bar-wrapped (C303) concrete pressure pipe, ductile iron pipe, PVC, and spirally welded steel pipe. This posed to be a challenge as the variations in the pipe materials properties and joint systems require that the design address the different aspects of each material from acceptable joining methods and corrosion protection system. The paper will review this project in detail from cradle to grave covering aspects from the initial design parameters and construction documents through the bidding process and construction completion. Included in this presentation will also be lessons learned through the design and construction process.

This presentation discusses an approach for detailed scour risk analysis of creek crossings for design of large diameter water transmission lines. Discussion includes risk categorization and methodologies utilized, including the City of Austin’s erosion hazard zone methodology and the United States Bureau of Reclamation Guidelines for evaluating pipeline channel crossing hazards to ensure effective burial. The presentation describes how tailored scour analysis for the Alliance Regional Water Authority’s Phase 1B treated water pipeline segment A resulted in informed design decisions, lower construction costs, and thoughtful creek crossing restoration.

Standing water, seeping groundwater, flowing river oxbows, and poor soil conditions can present significant challenges for the design, construction, and operation of a large diameter water line. The Raw Water Pipeline for the Sabine River Authority of Texas (SRA) faced these challenges for the 7 mi of 66-in. water line. This paper will discuss design modifications and construction methods to mitigate these challenging ground conditions during construction and operations. Design considerations included modified trench sections, evaluation of embedment materials, and the use of filter fabric around the embedment. To mitigate concerns during construction, the contractor potholed ahead of the pipe laying operation, lined the right of way with dewatering pumps, and phased construction. This presentation will help engineers, contractors, and owners identify best practices for design and construction of a water line through poor ground conditions.

Combination air vacuum valves (CAVs) are installed at water and wastewater system pump stations or at high points along pipelines to reduce or prevent vacuum pressures upon power failure. They prevent vacuum conditions by admitting air into the pipeline when the hydraulic grade line (HGL) drops below their elevation. Once pressures rise, the admitted air is discharged out of the pipeline (atmospheric pressure). Engineers select proper CAV sizes among miscellaneous models in industry and simulate their function during transient event using computer models. Air inflow and outflow mechanism, different for each CAV model, influences the transient pressures. This paper investigates the impact of commercially available CAV models on transient response of wastewater pumping systems. A case study is presented and the influence of two commercially available CAV models on the effective number and location of CAVs in the system is investigated by a transient simulation using HAMMER software.

Established fewer than 15 years ago, the Shirley McClellan Regional Water Services Commission (SMRWSC) is a municipal organization established by the Province of Alberta, and it has developed the longest regional water system in Alberta. The 150 mi, or 250 km, transmission system was constructed in five phases and services over a dozen communities, with a Phase 6 expansion scheduled for completion in September 2021. Rural water distribution systems developed by the Commission’s various member communities have extended over 100 mi (160 km) in that time to create an extensive water network that provides sustainable water servicing to a large geographical area. This paper provides a history of the system from the early days of planning the full network to the buildout of the various phases, the unique pumping station at the heart of the system that services four independent pressure zones, and it discusses how design approaches and construction methodologies have changed over that time based on new and improved materials, the emergence of horizontal directional drilling as a cost effective competitor to open cut installations, and changes to the basic design philosophies behind control networks.

Since AWWA approved and published its first plastic pipe standard, C900, 46 years ago, the use and acceptance of plastic pipe for potable water distribution/transmission pipe, reclaimed water pipe, wastewater force-mains, and irrigation pipe has grown steadily. AWWA’s PVC Pressure Pipe and Fittings Technical Committee worked diligently for more than five years to update Manual 23 (M23), PVC Pipe—Design and Installation. That effort was culminated with the 2020 publication of M23’s 3rd edition. AWWA M23 provides both general and technical information to aid in design, procurement, installation, and maintenance of PVC pipe and fittings. It serves as a consensus reference book for utilities and municipalities, consulting engineers, utility construction personnel, and installation contractors. The paper will examine the advancements over the last fifteen years which have been incorporated in the new, 3rd edition, together with lessons learned regarding the best practices for PVC and PVCO pipes and fittings. This paper will also highlight the information provided in new chapters that address trenchless installation and thrust restraint. These and other important design and installation updates will be summarily reviewed.

Originally designed to service a defined set of communities in Parkland and Lac Ste Anne Counties west of Edmonton, AB, the service footprint of the West Interlake District (WILD) Regional Water System has been expanded multiple times in under 10 years to service additional communities, First Nations, and recreational developments in need of an assured, high quality source of water. From an original system length of 35 mi (56 km), the system length has more than doubled, and capacity doubled with construction expected to be completed in 2021. The paper outlines how the system was originally planned and how changes to demands changed the system hydraulics and necessitated additional potable water reservoirs, booster stations, as well as the retrofit of existing facilities. The paper will also discuss how truck fill stations were incorporated throughout the system design to enable the affordable provision of potable water servicing to area farms throughout the region.