Pipelines 2023: Planning and Design

A 2-mi-long ductile iron pipe replacement project in Lawton, Oklahoma, required a major stream crossing as a part of the replacement segment. Preliminary design observations were made on the limited pedestrian accessibility to cross the channel while investigating the best method of installation for the waterline crossing. Collaboration with the city and design team led to a feasibility study to select pipe and bridge types that would provide a dual pedestrian crossing and waterline crossing. Ultimately, a pipe/pedestrian bridge design was selected and designed. This paper details the alternatives analysis process and shows the configuration and selection of the bridge type. Details of the creek cross section, environmental considerations, and bridge cross section are included. Selection of the optimal bridge configuration to mesh with the pipe and pedestrian needs are included (e.g., security considerations, air valving, decking, and railings).

Occasionally pipeline designers encounter situations where a bridge-supported aerial pipeline installation is necessary. This may occur at crossings of rivers, canals, ravines, highways, railroad tracks, or other obstacles where routing under or around the obstacle is unfeasible or impractical. These crossings present unique challenges not encountered in a buried installation, including pipe acting as a beam, pipe support, bracing and anchorage, movements induced by thermal effects, Poisson effects and the supporting structure, thrust restraint and transition back to buried conditions, among others. Factors affecting the aerial pipeline design include whether the pipe is pressurized or not, pipe material, joint types, and vertical and lateral support options. Installations must also consider constructability and maintenance access. This paper will provide an overview of common bridge-supported pipeline types, discuss the issues designers must consider, compare and contrast different installation types, and present some lessons learned from recent installations.

In 2016, a joint venture that includes Jacobs Engineering, Inc. was hired to complete the design-build of a new 360-MGD (expandable to 540-MGD) water treatment plant for the city of Houston (COH) and its partners. This new facility is known as the Northeast Water Purification Plant (NEWPP) and draws water from a new intake on Lake Houston and conveys it approximately 2 mi to the site of a new water treatment facility. Due to shallow depths of Lake Houston and raw water intake requirements of the Texas Commission on Environmental Quality (TCEQ), the new intake pump station is located approximately 1,000 ft offshore, requiring a bridge used for access and utilities. Conveyance of the raw water is through twin 108-in. diameter welded steel pipes that utilize a bridge to connect the offshore pump station to the land and ultimately the water treatment plant. Design of these 108-in. pipes was coordinated closely with the bridge design to ensure both objectives were met for loading and support spacing. Ultimately, a 50-ft spacing was selected for the bridge spans and pipe support lengths. Design of the support systems on the bridge required special consideration due to large differential in thermal expansion, while inside the pump station further consideration was given to stresses combined with thermal expansion forces. The design-utilized ring girder style supports commonly found in penstocks combined with fixed and dimensionally flexible supports to support and restrain the pipe while accommodating thermal movement without exceeding allowable pipe stresses. The design required special stress analyses to ensure all piping stresses are accommodated for the piping limits as well as the more important aspect of not placing damaging forces on the pumps through the discharge piping.

Black & Veatch is currently leading the engineering design services for a capacity expansion of the Doe Branch Discharge (DBD) facility for the city of Irving, Texas. These services include hydraulic design, transient analysis, selection of flow control valves, commissioning, testing, and calibration of the improved facility. Jim Chapman Lake, in Texas, is one of the primary water supplies for the city of Irving (Irving). Irving owns and operates a large water supply system in partnership with the North Texas Municipal Water District. The 100-mi, 72 and 84-in. raw pipeline conveys water from Jim Chapman Lake to both Lavon and Lewisville Lakes. Irving’s portion of the water is discharged into Doe Branch Creek through a flow control facility and stilling basin located in Prosper, Texas, just upstream of Lake Lewisville. The DBD facility is hydraulically controlled by a ground storage tank located in Prosper, Texas. Because everything is or gets bigger in Texas, up to 104 million gallons per day (MGD) are anticipated to be discharged in the summer of 2025 through this 20-year-old facility due to current expansion of the Lake Chapman Conveyance system, which will also receive and transfer up to 55 MGD to Lake Lewisville in 2025 from the Upper Trinity Water District’s Lake Ralph Hall Project. Black & Veatch is currently leading the engineering design services for rehabilitation and expansion of the DBD facility. This paper provides details on Irving’s capacity expansion needs and O&M requirements, identifies the methodology and models developed for the analysis, and summarizes the findings and recommendations which include removing the only flow control valve currently in the facility (42-in. sleeve valve—20+ year-old and partially operational) and adding two trains of 36-in. multiple orifice valves (MOV) inside the existing 20-year-old valve vault. Each 36-in. train includes upstream and downstream isolation butterfly valves and a dual configuration of MOVs to handle the large range of water flow rates and maintain pressures the system requires.

Air in water distribution systems and feedermains (water mains) may lead to serious operational issues. Trapped air pockets can cause a reduction in capacity, induce transients, or even give rise to sudden failures with potentially significant consequences. Air release valves are typically installed to remove air from water distribution systems; however, guidance on air valve placement is typically limited to placement at high points, spacing at mostly regular intervals, and changes in grade. Most guidance does not provide sufficient background to fully assess air valve placement and sizing. Henry’s law describes the relationship between dissolved air and pressure, and in conjunction with the temperature dependence of equilibrium constants described with the Van't Hoff equation, this paper applies Henry’s law to establish the potential for dissolved air within water and then to determine where air may remain dissolved or may come out of solution at any given location in a water system. Finally, practical considerations for air release valve placement, including a recommended air valve configuration, are proposed to capture and remove entrapped air from within water mains.

Valves are critical to system reliability and emergency response, especially as pipelines age. In any condition assessment project, if you cannot properly control the flow of water, then performing any pipeline assessment work will become difficult or impossible. However, with proper valve assessment, valve operability can be verified to ensure proper shutdown prior to pipeline assessment work. This paper will discuss the types of valve assessment and present a case study of the Glendale prestressed concrete cylinder pipe (PCCP) Transmission Main Assessment Project, where valve assessment and pipeline condition assessment were successfully coupled.

Customer demand for water supply services has changed from quantitative to qualitative, and the need for services is increasing. This study aims to develop a multi-objective model that minimizes water supply risks and costs by installing additional control valves to achieve the level of service demanded by consumers. As a result of applying the model to an existing water distribution network with a current water suspension risk of 22 h in a year, an optimal control valve location was derived that could reduce the risk by 45%. Installing additional control valves was found to be a more appropriate alternative than replacing the aged pipes. In addition, the model was verified to derive the optimal solution through the Pareto solution under various conditions. This study provides a reference for establishing plans for future water distribution network (WDN) management.

Operability of buried butterfly valves has been the concern of design engineers, water utilities, and manufacturers due to the complex behavior of pipe-valve as a unit system. Moreover, deflection control and stress limits are typically considered in designing buried pipes and valves. When the pipe deflects to the allowable limit (2% to 5%), the buried valve cannot operate normally, and binding and sealing issues may be observed. However, prediction of the pipe/valve deflection not only depends on the pipe/valve stiffness but also on other factors such as backfill material type and strength, location, and dimensions of reinforcing parts (butt strap and stiffening ring). To this end, nonlinear finite element analyses (FEA) of a case study from the IPL project of Tarrant Regional Water District (TRWD) were carried out to study the behavior of a large diameter buried pipe-valve system, and to investigate the effects of different pipe-valve system properties and dimensions. The aim of this study is to clarify some of the concerns in the industry regarding the operability of large diameter buried butterfly valves and provide recommendations based on the results of the current FEA. The article presents a summary of the key findings for consideration when designing a large-diameter buried pipe-valve system.

Great Lakes Water Authority (GLWA) experienced a catastrophic failure of a prestressed concrete cylinder pipe (PCCP) segment in the 14 Mile Rd. Transmission Main (TM). This TM was not part of a looped system, and this failure resulted in the loss of water service to residents in GLWA service area. GLWA decided that the 14 Mile Rd. TM must be interconnected to the 8 Mile Rd. TM so it is in a looped system. A route study determined that the 14 Mile Rd. TM Loop should be placed in Michigan Department of Transportation (MDOT) right of way (R/W) and in the City of Novi’s city streets. This paper discusses the need for the pipeline, benefits and challenges associated with installing the pipe in an MDOT R/W, the tunnel design and construction requirements, the micropile design and bidding strategy, as well as other construction and design lessons learned.

Los Angeles Department of Water and Power, the nation’s second-largest municipal water utility serving over 4 million residents, is upgrading its aging infrastructure including the existing River Supply Conduit, Upper Reach (RSC) trunk line. The existing RSC is a major transmission pipeline connecting the San Fernando Valley to the Central service zones. It was built in the 1940s and is a 51-in. riveted steel and concrete pipeline with an approximate length of 31,500 feet. The replacement project installed 28,792 linear feet of 78-in. diameter welded steel pipe by tunneling and cut and cover methods. It was originally designed as three units and constructed under two contracts. Units 5 and 6 installed a total of 15,536 linear feet, and Unit 7 installed a total of 13,256 linear feet. The project is expected to complete construction in June 2023.

The Los Angeles Department of Water and Power (LADWP) is building the North Hollywood Central (NHC) Treatment Facility to address groundwater contamination at five remediation wells, restoring the beneficial use of the city of Los Angeles well field. The project will include the installation of two parallel welded steel pipelines to convey water from said wells to the NHC Treatment Facility. The project will utilize open-cut and micro-tunneling construction methods to install a 6,760-ft-long collector pipeline ranging from 20- to 36-in. diameter and a 6,598-ft-long, 16-in. diameter purge pipeline. The project successfully navigates various challenges: micro-tunneling under high-voltage overhead transmission lines, crossing railroads with multiple jurisdictions, sharing a congested corridor with existing and proposed infrastructure, and crossing busy traffic intersections, all the while staying on an expedited schedule and reducing the impact to nearby businesses, residential neighborhoods, and existing substructures. The project is currently in 100% design and scheduled to start construction by early 2024.

Designing infrastructure in a rapidly growing city like Austin, Texas, brings many challenges such as overlapping public and private projects and working in bustling, congested corridors. Adapting to changes in the project scope on the fly is key to delivering a project and avoiding costly change orders in construction. This presentation will focus on highlights from the Upper Boggy West Wastewater Line Improvements Project in east Austin, which includes over 5,000 LF of 36-, 24-, and 15-in. wastewater line and over 2,000 LF of 24-, 12-, and 8-in. water line improvements, including over 2,000 LF of trenchless construction.

In 2017, five Denver Metro area entities collaborated on a regional wastewater master plan (Plan) with the goal to eliminate lift stations and provide a sustainable solution for wastewater conveyance and treatment for the region. The plan identified over 25 mi of new gravity interceptors required to eliminate seven lift stations and convey wastewater to a recently constructed treatment plant on the north side of the Denver Metro area. Implementation of the interceptors proved to be more difficult than presented in the Plan due to award-winning and championship golf courses situated near the natural drainageways the interceptors were required to follow. This paper focuses on the design and construction considerations necessary to install the 60-in. and 42-in. diameter interceptors through two golf courses in the Denver Metro area. A detailed discussion of the alignment optimization necessary for stakeholder acceptance, groundwater control, and balancing the viability and costs associated with tunneling and open cut installation methods is presented.

Some agencies, standards, and manuals recommend compacting embedment soil for a buried flexible pipe to a level of 6 to 12 in. above the top of the pipe. This practice is often unnecessary, a waste of resources and invites damage to the pipe. It is unnecessary because side support is only needed up to about 70% of the outside diameter (0.7 OD) of the pipe to limit pipe deflection. Compacting unnecessary embedment is a waste of resources and money. Furthermore, compacting on top of a pipe risks damage to the pipe. This paper discusses the recommended 0.7 OD limit for embedment compaction about a buried flexible pipe. Reasoning, numerical analyses, and laboratory experimentation are presented that support this limit.

Since the mid-19th century, water supply has largely been a matter of transportation. Water distribution and transmission pipe infrastructure is a critical underpinning of the developed world’s health, safety, and economy. Hence, scoring the performance of these subterranean pipe assets is an essential element for achieving greater sustainability. Recognition that different pipe materials/products deteriorate at different rates and for different reasons is essential to making informed decisions that optimize water infrastructure performance and longevity. Understanding how different pipes perform requires tracking and measurement over time. This paper focuses on the importance of keeping score, that is, analytically documenting pipe performance to gain an understanding of how and why their performance is compromised. Scorecard information is relevant, factual, and unbiased. Examples of how pipe performance data has been used to predict and improve durability are discussed. Performance curves for several pipe products commonly used for water transmission and distribution are reviewed. Scorecards can also invaluably help utilities define, monitor, and communicate progress toward strategic objectives. Scorecards help reduce subjectivity, increase accountability, and improve strategy execution. Scorecards enable utilities to integrate key pipe performance metrics into planning, budgeting, and forecasting processes, while creating reliable institutional knowledge of their water distribution systems.

Reinforced concrete pipes (RCPs) are made of concrete and steel reinforcements, which have been widely used for sewerage, water drainage, and industrial wastewater conveyance. There are two major design methods for the RCP: direct design and indirect design methods. In both designs, due to the existence of tensile stresses at both the inner and outer surfaces of the RCP, the standard practice is to place the circumferential reinforcements in two layers along the pipe thickness. ASTM C76 is a tabulated designated RCP specification, which categorizes the RCPs into five classes based on the concrete strength and load-bearing capacity. However, the task of placing two cages of reinforcement is time-consuming, expensive, and sometimes unnecessary, especially for some pipes in classes III, IV, and V. Therefore, this study aims to investigate the feasibility of reducing the RCP’s conventional double cage circumferential reinforcements to one and proposes a proper location for the successor equivalent cage in the pipe thickness through a three-dimensional non-linear finite element analysis (FEA). The FEA models were verified with three experimental tests using the three edge-bearing tests (TEB) method. The numerical models were developed for RCPs for classes III, IV, and V for pipe diameters ranging from 24 to 72 in. Three different locations along the pipe thickness were considered for the equivalent reinforcement cage. The results showed that one cage of reinforcements in some pipes satisfies all the ASTM requirements, thereby making it possible for manufacturers to produce reinforced concrete pipes with a smaller amount of steel reinforcements, saving time and cost.

How do we assure a pipeline’s resilience against earthquakes, storms, and flooding? How do we prepare for aggressive soil conditions which may otherwise pose a challenge to a buried asset’s longevity, and how can that longevity be protected, assured, and even extended? How can today’s pipeline infrastructure serve a changing and challenging tomorrow? This paper will briefly outline the latest ductile iron pipe product developments to provide resilience against earthquakes, storms, and flooding. It presents research and field data from both in situ soil and corrosion studies as well as monitored results from an operational pipeline in a soil environment known to be exceptionally corrosive. A photograph from Hurricane Matthew will show resilience against impact. A photograph from Hurricane Harvey will show the importance of joint restraint in areas subject to flood and washout of supporting backfill. The Everglades is known to be among the most aggressive soil environments in North America. This paper’s in situ soil and corrosion study was conducted there and employed an empirical two-dimensional likelihood and consequence of corrosion matrix. The soils scored maximum on the likelihood scale. Pipe samples buried in the Everglades, monitored with corrosion probes, and then exhumed and examined will be presented. Further, an operational pipeline installed in Mid-western/Great Plains soils having a proven record of causing premature corrosion failures will be presented, including monitored corrosion rates and corresponding service-life projections. Life-expectancy projections from the corrosion probe monitoring data from both sites are included and can be of tremendous value to utility owners and operators in a variety of arenas from financial to operational, maintenance, and otherwise. What if utility owners could project with greater confidence the long-term joint resilience and life-expectancy of their ductile iron and steel pipeline systems? This paper will show how they can.

The Glenridge 66-in. Water Main Relocation consisted of installing 3,229 linear feet of steel water main via open cut and trenchless methods as a utility component of the Purple Line Light Rail Transit System Project. The project was to be completed within a 23-ft-wide median of a major Maryland Department of Transportation four-lane thoroughfare. The project owner and design engineer carried out the decision to involve the contractor between the 70% and 90% milestones of project design progression. The project benefited from the early contractor inclusion in the forms of enhancing pre-construction activities; allowing for the completion of time-of-year restricted tasks prior to constraints; concurrent design progression and material procurement despite delayed supply chain conditions; timely maintenance of traffic plan modifications; and early identification of risk. The advanced collaboration resulted in elevated levels of cost certainty, accelerated resolution of unforeseen issues, and limited variance from the initial critical path schedule.

Joints in buried municipal pipes are arguably one of the most critical components of the overall system, the weak link that determines the integrity of water and wastewater systems against leaks and inflow/infiltration (I/I). Elastomeric or rubber gasketed “push-on” or “bell-and-spigot” joints are one of the most common ways by which pipe sections are joined. The American Water Works Association’s (AWWA’s) Manual of Water Supply Practice M75 Elastomers for Waterworks: Pipes, Valves, and Fittings is the first manual of its kind and focuses exclusively on the elastomeric gaskets that seal the various types of joints. While pipe joints are discussed in AWWA M75, an understanding of the unique joint types of each pipe material is not covered in depth. This paper focuses on the state-of-the-art of joints found in two of the most widely specified pipe materials in water and wastewater systems: polyvinyl chloride (PVC) and ductile iron pipe. Discussions will also include joints of other pipe materials including thermoplastics such as corrugated HDPE and thermosets such as fiberglass pipe; vitrified clay pipe (VCP); spiral welded steel pipe; and both pressure and gravity concrete cylinder and non-cylinder pipes. Properties of elastomers for each joint type as outlined in pertinent standards will also be discussed and summarized.

The origins of AWWA C207 and ASME Boiler and Pressure Vessel Code (BPVC) ring flange design can be traced to integral flange design procedures developed in the 1940s. However, AWWA C207 publishes flange dimension tables without consideration of pipe wall thickness, and without providing equations or test data to support the tables. This paper discusses the history of AWWA C207 published tables and compares it with ASME BPVC ring flange calculations, and how that comparison affected a recent major water project in Vancouver, British Columbia, Canada.

Thermally sensitive internal linings such as epoxy or polyurethane are often used to protect the interior of steel water pipelines from corrosion. Welded joints are usually required for higher pressure pipelines and to provide axial restraint. When welded joints and thermally sensitive linings are specified, the heat from welding would degrade or destroy any thermally sensitive lining in the vicinity of the weld. Therefore, the industry standard is to hold back the lining in the heat-affected area of the pipe ends to be welded and to patch the lining in this area after the girth welds have been completed. Field-patching of epoxy or polyurethane linings is prone to present the quality issues common with field-applied coatings. Adverse environmental conditions and the difficulty of inspecting coating quality in the confined space inside of a pipeline have commonly led to patch failures. Furthermore, the process of patching the weld zone after welding significantly slows down construction, increasing its cost. This paper reviews the use of an internal joint protection sleeve that is installed during new construction to protect the bare steel pipe at the weld zone from corrosion. The keys to the internal sleeve functionality are to prevent water from reaching the weld zone, withstand welding heat, and to be easily installed. Shop test results, third-party qualifications, and field installations are presented.

Code-compliant welding details may not be well understood by the engineering community and are often left up to pipe fabricators and welders. Engineering awareness of welding details, including code welding geometry, can contribute to the success of water industry projects. This paper will address code welding details required for mitered elbow compliance, including example calculations of welding bevels. In addition, a chart will be provided, which details bevel versus rotation angle for mitered elbows with 60° single V-Groove welds for various miter deflection angles from 1° to 60°. This chart will eliminate complex calculations, making code compliance easier for welders.

The presentation will review risk mitigation strategies to facilitate a successful public bid when an industrial developer acquires property after the design is complete but prior to acquisition of all required easements. Several decisions made by the design team as the project progressed had the potential to cumulatively increase the risk of the overall project. A review of risk mitigation techniques implemented (including evaluating proposed construction durations, timeframes, and impact to future land use) was used to successfully negotiate easement acquisition and allow the project to proceed. The project was substantially complete with three HDD crossings and tie-ins complete in early 2023. Connection to the existing reclaimed pipeline was completed on December 6, 2022, and the connections to the existing sludge pipeline on January 11, 2023. As of early March 2023, a new automated security gate and environmental site remediation activities remain to be completed before final completion is achieved.

Eastern Municipal Water District (District) needed to increase wastewater conveyance capabilities within previously built-out historic commercial area of Old Town Temecula, California. This special water district evaluated several different alignments and construction methods, but with the heavily commercial area being only three blocks wide and dozens long bounded by a freeway on one side and a Murrietta Creek on the other, very few options were viable. Several different construction methods were considered for increasing capacity of the existing collection system. Initially a 36-in. microtunneled casing and carrier pipe was considered, but ultimately replaced with a less expensive option: auger boring method. Once construction started, however, every drive attempt failed. Construction was completed by greatly exceeding the accepted drive lengths of traditional jack-and-bore. This paper describes the trenchless method evaluations and the ultimately successful construction method.

Do utilities know the best place to put new pipeline infrastructure? We think so. But does the data support those decisions? How can we demonstrate to the public that we are doing our due diligence? How do we show that the process is more than qualitative considerations? What if the pipeline is nearly 30 mi long and 66-in. in diameter, winding through protected wetlands, 10-lane interstate highways, dense residential neighborhoods, and established commercial business areas? What about estimated construction costs up to half a billion dollars? Tampa Bay Water and Hillsborough County (HC) were faced with these exact questions as they looked to finalize an alignment for critical future pipeline infrastructure. Pipeline route evaluation and selection is not a one-size-fits-all approach. It is usually tailored to the project scope and funding available, accordingly scaling up or down, to align with the end needs of the project stakeholders. For this project, the non-cost evaluation process was broken into the following key steps: (1) screening of a universe of options to a manageable shortlist; (2) a stakeholder-driven weighting criteria pairwise exercise to determine relative importance of key evaluation criteria; (3) data collection and visualization: using a “real-time,” accessible, online GIS platform to establish preliminary route corridors and set baseline evaluation metrics to “evaluate” various routes; (4) selection and development of sub-criteria to provide more discreetly definable and measurable evaluation characteristics and quantitatively measuring seemingly intangible evaluation factors such as public inconvenience; and (5) a quantitative methodology to integrate non-cost criteria (unitless) and cost (dollars). Simply adding the two does not work, as the units are incompatible. With this groundwork completed, the once-complicated decision becomes an effort of using the data to drive decisions.

Identifying a suitable site for a pump station while accounting for future service expansion can be a challenging task due to availability of land. Combined with a 66-in. water line route study in a diverse urban environment to supply the pump station and provide maximum benefit for two wholesale water providers (to extend service to their customers) presents a myriad of challenges due to the existing utilities, facilities, roadways, and residences. This paper presents how the NHCRWA Project 23 Route Study and Pump Station Siting effectively manages the challenge through a method of evaluation criteria, matrices, and scoring. Due to the pump station siting requirements, an appropriate pump station site had to be identified early in the process. The concurrent 66-in. water line route study employed a two-tier evaluation approach to more efficiently determine the optimal route from over 25 variations. Additionally, optimal locations were determined for the NHCRWA and the city of Houston to extend distribution lines to their respective customers in the efforts to serve surface water and reduce groundwater usage.

When El Paso Water’s Frontera 3.6 mi-long dual steel force main began to fail in 2020, an emergency project was initiated to replace the pipes. Phase 1 improvements included 1.3 mi of new fiberglass reinforced polymer (FRP) pipe installed essentially parallel with the old pipes. This minimized the need to acquire new easements and provided flexibility for connecting back to the existing force mains to minimize costs. To replace the remaining 2.4 mi of aging pipes entirely to the Hickerson Water Reclamation Facility (WRF), Jacobs and EPWater completed further route analysis. Replacing within the same easement presented a number of conflicts, while replacing parallel to or in place of the existing pipe was also not a preferable solution due to the high cost of bypass pumping to the WRF. This presentation will demonstrate how the project team utilized “Route Scout,” a route analysis tool to remove bias and develop a preferred route considering site restrictions and stakeholder priorities. We will delve into the restrictions faced in west El Paso, including the political issue of state borders, avoiding newly constructed TxDOT facilities, groundwater, contaminated soils, congested streets, and working with private landowners to acquire new easements. As field investigations began as part of the design process, new information emerged on restrictions along the preferred route. As this new information came to light, the tool was used as a live component of the project and alternative segments became the preferred route. Between El Paso Water, its customers, TxDOT, and local business on the existing and along potential routes, there were many stakeholders and their competing interests to consider on this project. The route study looked to understand these interests, minimize impact, and consider all interests to the project. By using Route Scout, these stakeholders and the site limitations could be quantified and compared to the costs estimated for the trenched, rehabilitated, and tunneled installation options to find the preferred route which is being built today.

Public rights-of-ways are frequently the corridor of choice for the installation of new pipelines. In evaluating the viability of these corridors, the widths of the right-of-way and the location of pavements and utilities are routinely considered. What may not be accounted for is the use of the public right-of-way by private entities and individuals. A close review of permit records and other historical data may find that over time, private individuals and privately owned business have taken over the use of a part of the public right-of-way. Owners and planners may also come upon these private and at times non-authorized uses of the right-of-way. Avoiding the non-authorized user’s facilities may cause the project unexpected delays and increased costs. Removing these non-authorized, privately owned, or perceived to be privately owned elements can pose challenges to the project both in costs and project delays. Unanticipated objections to the project may also arise from the perceived taking of private property or the perceived approval for the use of the public right-of-way by individuals. This paper will present examples of these situations and potential ways to mitigate impacts and objections.

The Alliance Regional Water Authority recently embarked on a major water supply program to serve long-term needs of its sponsors in Central Texas. This water supply program includes installation of approximately 80 mi of transmission pipeline that required acquisition of more than 250 easements on private property. Acquisition of these easements coincided with one of the most significant real estate market spikes in recent history in one of the fastest-growing regions in the United States. This case study focuses on how easement acquisition process unfolded and what lessons were learned during the process.

With the increasing necessity and demand for trenchless construction in urban environments, the use of precast concrete tunnel lining (PCTL) for tunnel boring excavations in select ground conditions has grown due to its ease of installation and increased quality control. For wastewater applications where the PCTL is designed to function as the host pipe, the typical assumed condition for optimal hydraulic performance is to fill all bolt and shear pockets. However, this activity can result in considerable schedule and cost impacts and requires the need to quantify the benefits. A literature review was completed to substantiate roughness coefficients applicable to PCTL acting as a primary liner, and a comparison of common hydraulic equations was performed to provide a sensitivity analysis. Based on the hydraulic performance assessment, not all bolt and shear pockets are recommended to be filled depending on the operational requirements of the wastewater conveyance tunnel.

If there’s anything the COVID pandemic taught us, its that our lives and normal daily habits had to be adjusted for reasons outside our control. A recent sewer basin study revealed much more than was anticipated during the pandemic. York County, South Carolina, a rural suburb just south of Charlotte, North Carolina, has seen steady growth in development as the Charlotte metropolitan area has grown. STV performed a sewer basin study to assess current and future sewer capacities for the basin. The hydraulic modeling study and field visits revealed how COVID changed the diurnal curve in this basin compared to what was expected or considered “normal.” The study also caused us to stop and consider exactly why this occurred. The results of this study revealed that a flatter diurnal curve with a greater afternoon peak (mirrored curve) was observed compared to a typical curve. This can be attributed to less commercial flow (or zero) and residential habits of getting up later, being home and using water throughout the day, and a consistent evening usage time (dinner, washing, etc.). This paper will compare diurnal curves from other basins of similar and differing taxonomy in the region, discuss how daily habits due to COVID changed the diurnal curve in an aged but actively developing sewer basin, and summarize the findings and recommendations of the study. How people used water throughout the day during COVID versus a pre-COVID normal daily life was an interesting finding. The paper will conclude with the engineer’s recommendations and options for the basin’s future build-out, which included a pump station force main, parallel relief sewer, or dig/replace the existing sewer (upsizing). This study allowed York County to better understand the existing flows and capacity limitations and project forward the ultimate capacity at basin build-out conditions.

The water industry always benefits from the testing of pipelines that have been in service for several years. Many of the recommended design parameters are based on laboratory testing, but those tests can only provide approximate predictions for headloss, for example. As an example, for potable water transmission and distribution pipelines, the design calculations may use nominal pipe sizes and assumed values for “roughness” of the inside pipe surface. Conducting field tests enhances laboratory values and provides insights into the actual performance of a pipeline after years of service. This paper reports the results of flow testing of ductile iron and PVC pipelines, both in service in single utilities. These tests provide insight into the sensitivity of the variables in the Hazen-Williams equation, such as the inside diameter and the recommended values for the C coefficient. In these tests, the headloss between two points on isolated pipeline sections was measured in order to calculate the relative values for the Hazen-Williams C. The results help us to appreciate which of the variables in Hazen-Williams equation control the headloss calculations and provide guidance on ways to improve headloss predictions for new pipelines.

While being filled, water and wastewater pipelines may be exposed to complex transient two-component (air and liquid) flow, which may impose significant transient pressures on the pipeline system. This paper presents a novel numerical model for simulating the transient response of water and wastewater pipelines during filling. Numerical exploration with a hypothetical pipe system concludes that (1) the resulting transient pressures depend on the shape and number of undulations in the profile of the pipeline; (2) the affirmation that the severity of the resulting transient pressures increases as the filling velocity increases; (3) irrespective of the filling velocity, undesirable transient conditions can be mitigated by properly sizing key air valves in the system; and (4) even a low filling velocity of 0.3 m/s may induce negative pressures in the pipeline when a high enough overpressure onset at an air valve is reflected at the filling water column front.

There are many design factors that are involved that must be considered when designing a piping system. Historically, safety factors have been used as an indicator of safety versus failure. The design strength values have been established for materials, and then a factor or multiplier has been applied to assure that the material does not approach the design strength value established. But how safe are these values for the final design? This paper will look at the use of safety factors based on design criteria for AWWA standard water pipe. We discuss how the safety factor is established and how that applies to the actual design of the pipe. We will look at how the actual pipe material is supplied versus the value used for the design. The paper will also discuss the relevancy of how the safety factor affects the final design. The conclusion of the paper will explain how the safety factor is just a guide for the engineer to use in the evaluation of AWWA water pipe.

Water conveyance design projects that are issued for contractor bids require carefully prepared plans and specifications. This paper presents several examples of items that frequently have been noted (and corrected) during recent quality control (QC) reviews and construction site visits. Topics include best practices for developing specifications, proper use of the NTS (not to scale) callouts, properly showing steel fittings, checking (and actually reading) the notes on drawings, proper and improper procedures to incorporate combined bends, the use of exaggerated horizontal and vertical scales, the importance of complete calculations, and the value of visits to the construction site by the design team. Several examples and suggested actions related to these items and others are included in the paper.

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 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.

This paper discusses the unusual structural demands encountered and innovative solutions provided for a critical large-diameter steel water transmission main in Houston, Texas. The 96″ and 84″ Project Segment B1 is part of the $1.2B Surface Water Supply Project (SWSP) for West Harris County Regional Water Authority (WHCRWA). The SWSP will utilize over 55 mi of large-diameter steel water transmission pipelines to convey potable water from the city of Houston’s Northeast Purification Plant to communities in West Harris County. Significant ground subsidence caused in part by pumping of water from aquifers and areas of naturally occurring slip-fault ground induced actions required the need for innovative design and solutions. The pipe-soil interaction from the expected long-term soil displacements in excess of 36″ required a pipe design that will assure long-term performance of the critical water transmission pipeline. For this project, the solution chosen by the engineers and the owner will use an innovative soil-steel pipe structure that utilizes common trench backfill materials with earthquake resistant steel pipe (ERSP) known as InfraShield joint system (patent pending). Advanced finite element analysis (FEA) utilizing the fully welded ERSP for both 96″ and 84″ buried pipe, as well as the 84″ vertical shaft piping for a deep tunnel under Beltway 8, backfilled in various common soil envelopes, was conducted. The FEA results verified the optimal solutions selected to meet the extreme ground displacement and strain demands on the pipeline. The paper reviews the FEA results of the buried pipeline and risers with the project trench details, along with ERSP performance capabilities and installation details. The paper discusses the fully welded earthquake resistant steel pipe FEA and structural pipe design details for Project Segment B1. The paper reviews the development, full-scale testing, and product details for the ERSP. The ERSP system and its innovative concept have been presented from its initial form at several ASCE Pipeline Conferences from 2017 to 2022 and validated with full-scale physical experiments and extensive numerical simulations via advanced FEA. The system is based primarily on the capability of the buried welded steel pipe material to sustain significant amounts of plastic deformation or strain at defined locations without leaks.

Few design procedures exist to account for seismic forces imposed on pipeline systems, let alone those that are practical to implement. This paper presents a practical approach to establishing the minimum required joint strength for welded steel pipe (WSP) under severe axial loading, including that from transient ground shaking. This work is based on previously established procedures developed by the Willamette Water Supply Program (WWSP, Program) in support of achieving their seismic resilience goals. The WWSP is a $1.6 billion program that 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. This paper discusses three methods to consider transient ground shaking and provides a practical step-by-step approach to solve for the required joint strength in sections of WSP pipe, including those in areas of high axial loading. An example is also provided for ductile iron pipe.

Past earthquakes have revealed the vulnerability of water infrastructure to earthquakes as water networks are susceptible to pipe damage (breaks and leaks). These damages can disrupt in the supply of water distribution. Seismic vulnerability assessment is essential for seismic rehabilitation decision-making. Although water pipe network uncertainties play a critical role in seismic vulnerability assessment methods, the impacts of these uncertainties have not been explored in optimal proactive seismic rehabilitation decision-making. Extant pertinent literature ignores the uncertainty related to water network properties. This research aims to explore the impacts of water network uncertainties on determining the most critical pipes vulnerable to seismic events within a limited budget constraint. Pipe roughness coefficient, demand, and reservoir head were selected as uncertain network parameters for this study. Sensitivity analysis was performed to quantify selected network uncertainties. A stochastic combinatorial optimization problem was formulated considering network uncertainties and seismic ground motion intensities to identify the most critical pipes of a network for limited rehabilitation budget. A simulated-annealing algorithm was used to solve the stochastic combinatorial optimization problem. Modena network was used to demonstrate the method. The optimization results showed that the selected network uncertainties significantly affect the identified critical pipes of the water pipelines. Also, the maximum achievable serviceability index for selected rehabilitation budget reduces significantly if network uncertainties are considered. This index has been reduced by 3%−4% due to the consideration of all three network uncertainties. It can be concluded that network uncertainties must be included with the current methodology of proactive rehabilitation decision-making due to seismic events.

As water distribution infrastructure ages, providers seek to improve water distribution systems’ ability to accommodate the significant ground deformations associated with earthquakes, fault rupture, landslides, liquefaction-induced lateral spreading, and other natural hazards. To address this susceptibility to damage from large ground movement, municipalities and design engineers are considering improved materials and jointing mechanisms, some of which have been seismically assessed through full-scale testing. This paper reports on a series of full-scale compressive loading tests performed on thermoplastic pipe at the University of Colorado Boulder’s Center for Infrastructure, Energy, and Space Testing. The full-scale compressive loading tests provide a framework for interpretation of experimental results through a seismic resiliency lens. The tests identify and interpret the pipeline’s axial response to, and failure mechanisms under, compressive loading when paired with various coupling types such as reinforced internal gaskets, external restraint systems, and traditional bell-spigot connections. Testing performed on 6-in. (150-mm) diameter iPVC (DR14) with varying coupling types is discussed and illustrates the axial response mechanisms of traditional continuous and segmented systems, as well as pipeline connections that exhibit combined behavior. Failure modes discussed include global/local buckling, joint telescoping, and bell fracturing, and are considered in the context of large ground deformation due to natural hazards. Displacement and strain measurements are employed to capture simulated pipeline response to ground movement parallel to the buried system as well as considerations for internal pressure build up due to axial loads. The presented failure modes provide guidance relative to an ongoing ASCE/UESI committee on seismic evaluation of pipeline systems 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. Procedures for interpreting experimental results and the implications for seismic design are discussed.

ASCE is currently developing a Manual of Practice (MOP) for the Seismic Design of Water and Wastewater Pipelines under the Pipeline Division of the Utility Engineering and Surveying Institute (UESI) in collaboration with ASCE’s Infrastructure Resilience Division (IRD). This MOP would include a prescriptive approach for seismic design of buried water and wastewater pipeline infrastructure that is potentially subjected to transient ground deformations (TGDs) and different types of permanent ground deformations (PGDs) such as those imposed by landslides, liquefaction-induced lateral spreads, and fault rupture. The work summarized in this paper pertains to an analysis framework being considered for the development of prescriptive design recommendations for PGDs from liquefaction-induced lateral spread hazards. An empirical approach based on the revised multilinear regression equations to predict lateral spread displacement has been adopted in developing the recommendations presented in these design tables, currently under consideration, for different pipeline criticality categories. This approach provides a mechanism to design water/wastewater pipelines against liquefaction-induced lateral spread hazards without undertaking significant and complex investigative, evaluative, and design efforts for certain conditions. Critical pipelines located within high lateral spread hazard regions, however, will require site-specific analysis and design. Due to space limitations, this paper focuses only on the framework used in developing the typical design tables.

The Stage V expansion of the Annacis Island Wastewater Treatment Plant (AIWWTP) consisted of the design and construction of a new outfall system, which included an outfall diffuser system consisting of two 2.5 m diameter pipes buried within the highly liquefaction susceptible bed of the Fraser River. Subsurface soils surrounding the diffuser pipeline are vulnerable to lateral and vertical permanent ground displacements (PGDs) of 1.55 and 0.30 m, respectively, due to potential liquefaction and lateral spreading hazards during the 2,475-year design seismic event. Design of the outfall diffuser portion of the project was very challenging due to several factors starting with the physical location of the diffuser, complex hydraulic and salinity conditions of the Fraser River, dilution requirements for the discharge, and liquefaction-induced lateral and vertical PGDs during the design seismic event. This paper presents a summary of the design challenges encountered and the design solutions developed, with particular focus on how the design accommodated the anticipated large PGDs using the special seismic steel pipe (SSSP) segments consisting of wave forms, known as “steel pipe for crossing faults (SPF).” A companion paper presents the construction challenges encountered in the project.

The Stage V expansion of the Annacis Island Wastewater Treatment Plant (AIWWTP) consisted of the design and construction of a new outfall system, which included an outfall diffuser system consisting of two 2.5 m diameter pipes buried within the highly liquefaction susceptible Fraser Riverbed. Subsurface soils surrounding the diffuser pipeline are vulnerable to lateral and vertical permanent ground displacements (PGDs) of 1.55 m and 0.30 m, respectively, due to potential liquefaction and lateral spreading hazards during the 2,475-year design seismic event. Construction of the outfall diffuser was very challenging due to several factors such as procurement of the special seismic steel pipe (SSSP) segments and other pipes from overseas fabricators, in-river and underwater construction, its location adjacent to a navigable channel, dredging, construction quality control during pandemic conditions, as well as fabrication, deployment, and construction of the outfall segments of the pipe while meeting the specification requirements. This paper presents a summary of the construction challenges encountered and the construction solutions implemented, with particular focus on how the construction of the outfall pipe buried within the bed of the Fraser River was accomplished. A companion paper presents the design challenges encountered in the project.

The San Diego County Water Authority (Water Authority) provides a safe and reliable water supply to more than 3.3 million residents through 24 member agencies. The 2nd Aqueduct pipelines serve the entire San Diego region and are considered critical infrastructure consisting of Pipeline No. 3 [72-in. (1,829 mm) steel welded pipe], Pipeline No. 4 [90-in. (2,286 mm) prestressed concrete cylinder pipe (PCCP)], and Pipeline No. 5 [96-in. (2,438 mm) PCCP] that pass through Moosa Canyon. Since 2019, these pipelines have started to exhibit vulnerabilities. Existing and ongoing threats to the pipelines where the 2nd Aqueduct crosses Moosa Creek, at the base of Moosa Canyon, include scour within the streambed, seismic effects (e.g., liquefaction, lateral spread, and potential slope instability), and other potential pipeline failure modes. The Water Authority has provided interim protections to these threats; however, if left unaddressed, these conditions may increase the risk of future failure. To mitigate these risks and ensure a state-of-good repair, mitigation of natural threats, and water supply resiliency, the Water Authority has completed a planning study to develop the project to rehabilitate, replace, relocate, and/or upgrade, as necessary, the pipelines. This paper documents the project background and pipeline threats, the range of repair and replacement alternatives identified, and the multi-step decision-making approach used for ultimately picking the “selected alternative” for implementation.

This study proposes improving a method for designing a water pipeline against fault displacement by incorporating long collar into hazard resilient ductile iron pipe (HRDIP) pipeline. A hazard resilient joint pipeline is capable of absorbing the large ground displacements by movement of its joint (expansion, contraction, and deflection) and the use of the joint locking system. Existing hazard resilient joint pipelines have been exposed to several severe earthquakes such as the 1995 Kobe Earthquake and the 2011 Great East Japan Earthquake, and there has been no documentation of their failure in the last 40 years. These performance records of hazard resilient joints are also highly evaluated in the West Coast of US; therefore hazard resilient joint has been widely adapted as a measure for fault, earthquake, landslide, etc. On the other hand, there are many faults which are estimated with large movements in the West Coast of US. In those locations, additional countermeasures are required when the fault displacement exceeds 1.8 m because this displacement could stress the hazard resilient joint pipeline beyond the elastic limit; therefore special countermeasures are adapted to increase the performance of the pipeline such as using long collar, which has an expansion/contraction performance more than 10 times as much as regular hazard resilient joint pipe joint. In this study, researchers conducted long collar joint deflection tests with fully expanded and contracted situations to make the relation between expansion/contraction and deflection performance clear. Based on the test results, researchers set the long collar’s joint deflection feature considering joint expansion/contraction accurately for finite element modeling (FEM) analysis and optimized the design of hazard resilient joint for fault movement.

Failure of buried pipelines can result in costly renewal and replacements (R&R), significant disruption of service, and may have substantial environmental consequences. Identifying failure-prone pipes for R&R can help avoid pipe failure. Desktop analysis of a pipe network along with analysis of the physical and geomorphologic characteristics of a service area is the first cost-effective step to develop a proactive plan for maintaining good service practice under various expenditure scenarios. This study presents GIS-based desktop analysis for sewer mains for the development of risk-based capital investment plan and project prioritization using KANEW model. The risk analysis was conducted, and pipes were ranked under five risk classes based on the likelihood of failure in terms of pipe age, useful life, material, failure pattern, soil condition, and consequence of failure in terms of social, economic, and environmental impacts to the system and service area. The cost of R&R from each risk class is also determined for project prioritization.

The state of Florida has been active in preserving and restoring the state’s water bodies. Part of this effort has included identifying pollutants and their sources. Accordingly, the state of Florida has identified total nitrogen (TN) as the main source of nutrient pollution and onsite sewage treatment and disposal systems (OSTDS), more commonly known as septic tanks, as a major source for TN. As a result, the state has enacted regulations to limit and reduce OSTDSs and has provided funding for sewer system expansions to aid in this objective. Utilities today are facing a challenge of expanding their sewer collection systems into partially or fully built-out areas currently served by OSTDS units. A key component of this challenge is selecting the correct sewer collection system for the existing and developed project area that will minimize impacts. This paper summarizes the challenges and advantages associated with vacuum sewer collection systems in meeting the state’s nutrient reduction goals.

The city of North Miami Beach (NMB), Florida, along with its utility department, NMB Water, is investing over $106 million in a five-year capital improvement program (CIP) for water and wastewater infrastructure improvements. The investment in general will allow the utility to reduce any possible service interruptions and continue with compliance with federal and local regulatory agencies. The overall capital improvement program investment is beneficial to the NMB Water service area that includes not only the city of North Miami Beach but also the cities of Aventura, Miami Gardens, Sunny Isles Beach, and Golden Beach and additionally portions of unincorporated Miami-Dade County. In order to reduce the impacts of user rates due to the capital expenditures, the city applied for and received funds from the Water Infrastructure Finance and Innovation Act (WIFIA). The WIFIA program accelerates investment in the nation’s water infrastructure by providing long-term, low-cost supplemental loans for significant regional projects. Additional funding is also being provided through several state and local grants, including the Florida Department of Economic Opportunity, and municipal bonds.

Implementation of large capital improvements projects is challenging. Municipal owners face large challenges in the installation of infrastructure to meet long-term needs. This type of project means construction and millions (or even billions) of dollars of public money. Owners face the daunting task of making the right decision as good stewards of the public resources with many competing interests vying for attention. When faced with large infrastructure projects, advice from many interested parties often can make the decision-making process even more stressful. Owners must weigh many variables to determine the best path forward with the standard triad of schedule, budget, and quality as the driving forces of the process. As an aid to owners in making the decision about how to procure construction contracts, a tool has been developed to allow cost, schedule, quality, and risk to drive the decision. Typical project delivery methods include: (1) Design bid build—traditional construction method that maximizes the owner’s control of the project. Cost is often optimized at the expense of schedule and, potentially, quality. (2) Competitive sealed proposal—a traditional construction method with an updated procurement selection that improves on quality and schedule. (3) Construction manager at risk—owners’ risk is managed in this method. Quality is high, and schedule can be greatly improved. Cost is usually higher. (4) Design build—schedule is maximized in this delivery method. Quality is high, and cost is usually higher as well. Other factors that may be included in deciding on procurement and delivery include owner selected and assigned equipment, prepurchase of equipment, and multiple project delivery methods. The paper provides a careful description of each delivery method and provides some examples of good uses of each delivery method. The next step covered in the paper is the use of a simplified tool to allow owners and consultants to answer some project-related questions to identify the key drivers for the project (risk, schedule, cost, and quality) and then assign a value to these items to help guide the decision-making process for large capital improvements projects.

The rapid reconstruction of pipelines is crucial in the aftermath of a disaster since the pipeline networks transport and distribute life-dependent supplies such as water, natural gas, and electricity. However, the sudden post-disaster cost inflation often deters the timely reconstruction of pipelines. It is significant to investigate the pipe cost changes after different types of disasters to understand the threat of each disaster to pipeline networks. This research aims to examine the pipe cost changes after six various disasters in Los Angeles that California Governor proclaimed. The results show that the winter storm and floods had the most significant impacts on the magnitude and extent of post-disaster pipe cost changes, respectively. Although wildfire and COVID-19 are the costliest disasters in terms of financial expenditures, their impacts on pipe costs are smaller and more marginalized than those of other disasters. The research findings can assist pipeline engineers and cost estimators in enhancing their reconstruction cost management and plans.

Zone 1 transmission main for the town of Gilbert consists of approximately 3.5 mi of 24-, 36-, and 48-in.-diameter bar-wrapped concrete cylinder pipelines installed under three contracts or segments between 1990 and 1993. A failure at a 36-in. diameter 45° bend, which occurred on June 29, 2018, prompted the town of Gilbert to initiate the assessment of the existing thrust restraint designs of Zone 1 transmission main. This thrust restraint assessment, which is the main focus of this paper, is part of a comprehensive assessment and rehab program undertaken by the town of Gilbert to ensure continued Zone 1 water supply. The adequacy of existing restraint length and cylinder thicknesses were checked using both the pre-2008 and 2008 AWWA M9 thrust restraint design procedures. A pre-design report was compiled, which includes the required restraint length and cylinder thicknesses for dead end thrust and horizontal and vertical bends; the report also includes discussion on the probable causes of the failure based on review of available photos and reports. The comprehensive assessment program includes field leakage tests, electromagnetic tests to detect corrosion, tests to detect stray current electrolysis, CCTV inspection to detect joint movement, and valve replacement. The tests performed are described, and results are presented in this paper along with an overall summary and recommendations.

Utility employees working in a water distribution system face inherent safety risks while working in confined spaces with distribution pipelines that may be energized. Disassembling pipelines within a vault may create two hazards: (1) excessive leakage through closed valves may flood the vault, and (2) thrust forces that occur when pressure builds up behind a closed valve, either within the vault or at a nearby buried valve, may lead to pipe movement, separation, or unanticipated rapid depressurization. Denver Water is the largest water utility in the Rocky Mountain region, serving over 1.4 million customers. Denver Water partners with 63 nearby distributor districts that maintain their own local distribution networks and to which Denver Water provides treated water via “master meter” connections that range in size from 4- to 12-in. in diameter. In 2019, Denver Water initiated a Master Meter Replacement Program to replace obsolete master meters for which spare parts can no longer be obtained. Over 110 master meters in more than 80 vaults were replaced through this multi-year program. These meter vaults have common design elements, including a bypass pipe within the vault, thrust restraint rods through the vault wall, and isolation gate valves. There are several unknowns that must be considered when developing an isolation plan prior to meter replacement. Such unknowns include the presence and condition of joint restraint in and around the vault and the operability of and expected leakage rate through existing valves. This paper presents case studies that exemplify the methodology that Denver Water has developed for managing these risks, which includes assessing the thrust forces that would result from closed valves that are known to be pressurized or may become pressurized, intentionally leaving valves open to reduce the risk of pressure build-up, performing test isolations, adding valves, and sequencing work such that customer service disruptions are minimized.

Traditional open-cut pipeline projects which generally face issues with heavy environmental constraints typically resort to trenchless methods to minimize environmental disruption. This paper will discuss an innovative construction and delivery approach where neither traditional open-cut nor trenchless construction methods were deemed feasible. The Sacramento Regional Wastewater Treatment plant located in Elk Grove, California, is completing the EchoWater Project, which is a massive upgrade project to comply with new effluent discharge permit limits. This project includes the design and construction of the Bradshaw Equalization Structure (BES) Pipeline Project that conveys partially treated wastewater through an environmentally sensitive wetlands area. Activity in this area is limited to minimal disturbance, and any type of excavation would present permitting challenges with a limited window for construction. Our innovative approach installed a pipeline that is unconventional in the wastewater industry inside an existing stormwater pipeline that runs through this environmentally sensitive area. This approach protects multiple vulnerable species and avoids expensive permitting timelines, realizing millions of dollars in savings.

Trenchless construction methods are used frequently for areas where open cut is not feasible, such as crossings of railroads, major roadways, and bodies of water. These installations often deal with difficult ground conditions and nearby or overlying infrastructure. Even when general guidelines for project planning and design are followed, such as performing geotechnical borings or including minimum equipment capabilities in project specifications, issues can still arise during construction. This paper will review several recent trenchless projects that have experienced construction issues, including obstructions and rock, unstable soils or sinkholes, and other installation issues. A general overview of the trenchless methods used, including microtunneling and pilot tube auger boring, and regional geology will be presented, along with potential risks and construction considerations of these methods. Lessons learned from these projects for consideration in future trenchless projects will be presented.

Risk-based models have long been used by the Southern Nevada Water Authority to achieve consensus decision making among its project stakeholders. For the Horizon Lateral Program, risk modeling was applied during the feasibility phase to identify two viable pipeline corridors for this new $1.6 billion water transmission facility. As the project has advanced into preliminary design, the risk factors primarily related to traffic impacts, utility conflicts, constructability, and cost were further considered as part of an alignment refinement process that included evaluations of applicable open-cut and trenchless construction methods. These evaluations have been extremely beneficial where new transmission pipelines will cross major streets and highways within the city of Henderson and surrounding developments in the southern Las Vegas Valley. This paper presents the Horizon Lateral Program and a decision tree approach that has been applied to identify and screen nearly 30 trenchless crossing locations, providing decision makers with a visual tool to balance construction risks and costs while ensuring minimal impacts to community traffic patterns.

The Willamette Water Supply Program (WWSP) is a partnership between Tualatin Valley Water District, the city of Hillsboro, and the city of Beaverton to develop the Willamette River at Wilsonville, Oregon, as an additional water supply source. This new system, when operational in 2026, will provide a reliable water supply for the region while also helping water system operators balance supply during times of drought or other supply interruptions, adding resiliency to recover more quickly after a large disaster, natural or man-made. The Willamette Water Supply System will include over 30 miles of water transmission pipelines in both 66- and 48-in. diameter. Twenty-five trenchless installations will be constructed in both urban and rural settings. These installations required evaluation of multiple technologies, development of contract documents, and the careful consideration of contractor proposals. The WWSP utilized a consistent approach to these efforts. This consistency resulted in using multiple technologies including microtunneling, guided auger boring, pipe ramming, and pipejacking. Shaft construction techniques also varied considerably. This paper will highlight the common elements used in planning, design, procurement, and construction of the trenchless installations and the results for the owner. A key finding of these installations is that contractor-based solutions require careful evaluation but can yield significant value for the owner. Expertise is required within the owner’s team to facilitate good decision making throughout the project life. Another key finding is that a standard approach to trenchless installations can be applied without limiting innovation or compromising project goals of safety, quality, and cost effectiveness.

An underground logistics system (ULS), also referred to as an underground freight transportation system, is defined as an unmanned, automated, and intermodal form of logistic transportation utilizing a network of pipelines to transport cargo between intermodal terminals. A linear induction motor propulsion system moves the vehicles carrying the cargo over rails through the network of pipes. The networks are built utilizing various construction technologies that are trenchless on available right-of-way (ROW) or under-existing facilities. The objective of this paper is to discuss several construction options to facilitate construction of an ULS, such as pipe jacking, utility tunneling, and microtunneling, as well as to present a theoretical case study to show the social and environmental benefits of ULS, such as air pollution reduction, relief of traffic congestion, and providing job opportunities for disconnected youth and disadvantaged communities. The framework discussed in this paper shows how underground pipelines can be used in ULS to promote efficient and healthy land use, create environmentally safe communities, decrease fossil fuel consumption, and provide significant socioeconomic benefits. Local and municipal governments can utilize the concepts discussed herein as a frame of reference to successfully adopt it for similar innovative transportation and underground projects to improve mobility through buried pipelines.