Pipelines 2020: Planning and Design

Dallas Water Utilities (DWU) is a leader in conserving valuable water resources in North Texas due to their proactive approach to pipeline management. DWU has implemented an annual condition assessment program of buried pipelines, preventing catastrophic failures and large-scale water-loss events which have enabled DWU to utilize innovative leak detection and electromagnetic technologies to improve their ability to effectively manage resources. Since inception, DWU has documented over 5,900 leaks and repaired or replaced more than 303 individual pipes which were approaching failure. This paper will present an overview of DWU’s successful condition assessment approach and leak detection program along with results and a few lessons learned since the program’s inception 15 years ago.

Force main pipes present a particular challenge in infrastructure asset management. Consequences of failure are higher for force mains relative to gravity pipes which increase the risk associated with these assets. However, unlike for gravity pipes, there are no industry standards for inspection and condition assessment for force mains. Furthermore, accessibility issues for inspections add to this challenge. This paper presents the new data standards for the force main pipe infrastructure asset management decision support. Nine utilities nationally distributed have provided data and support for this research. A data standard of 96 parameters was developed to capture the physical, operational, structural, environmental, financial, and other factors affecting the performance. This data standard was reviewed by various participating utilities and service providers for completeness and accuracy.

Implementation of advanced and fit-for-purpose asset management strategies requires careful and thoughtful assessment of the physical conditions of buried, large diameter pipelines used within wastewater collection and conveyance systems. Knowledge of the structural integrity and hydraulic performance of these critical assets is therefore crucial. It provides guidance to municipalities and utilities on (1) prioritizing repair and replacement projects; (2) avoiding costly and disruptive emergency repairs; and (3) minimizing public and environmental impacts. The current work reports the development of a systematic methodology for conducting a condition assessment, for rehabilitation/replacement design, of large diameter sanitary and stormwater sewers. The methodology employs a risk-based asset management strategy coupled with risk management and condition assessment practices for prioritization of infrastructure assets based on criticality and direct and indirect impact of their potential failure on ‘Triple Bottom Line’. The proposed framework is based on sound engineering concepts and field experience. It is practical and simple to follow, and it has been successfully demonstrated to establish asset management and renewal/rehabilitation prioritization plans for different sewer rehabilitation projects across North America. The case study provided in this work demonstrated that integrating risk-based assessment approach into the conventional condition-based approach will not only capture the current structural integrity and hydraulic performance of these critical assets, but will, most importantly, account for the direct and indirect impact of their potential failure on ‘Triple Bottom Line’. This will help municipalities stretch their limited rehabilitation budgets and narrow the ‘infrastructure gap’ by enabling a ‘just-in-time’ investment strategy.

Despite the large quantities of utility infrastructure data and various DOD processes, there was no management of that data in a central repository where it could be analyzed effectively for asset management. U.S. Pacific Air Forces (HQ PACAF/A7OP) engaged AECOM to develop and implement risk-based decision support for their wastewater infrastructure asset management. A consistent, repeatable approach for infrastructure requirements prioritization and investment across PACAF’s portfolio of installations was developed and implemented for over nine installations worldwide. The risk-based decision support system utilizes a GIS platform with ArcGIS software, along with CartoPac (a data collection/management tool). Relational databases were developed for PACAF for each type of infrastructure, to include attributes, that will store the probability of failure and criticality data for each asset. These tables relate and join to the DOD’s spatial data standards for facilities, infrastructure, and environment (SDSFIE) GIS structure. SDSFIE attributes are recorded to that geodatabase, while additional conditions and operational data are recorded in relational databases. Sub-meter GPS-enabled devices were used to map the water assets. Visual condition assessment surveys were conducted and supplemented with engineering analysis such as hydraulic modeling. Visual condition assessment surveys were conducted and supplemented with tools such as polecams, CCTV cameras, and flow monitors. A reporting service called business intelligence and reporting tools (BIRT) was developed to be used in a server enterprise environment. Report templates are informed by the underlying GIS and risk scoring data and are updated in real-time. The system provides the DOD with information required to rationally address high-risk requirements, gradually upgrade systems to required levels of service, and improve O and M management.

The American Water Works Association (AWWA) published the buried no longer (BNL) report in 2012. This informational and marketing report argues that costs will continue to increase, at more cost to consumers, and documents regional differences. AWWA estimates that $1 trillion is needed over the next 25 years in order to repair these infrastructure systems. The report argues for the development of comprehensive strategic investment plans that will help to reduce costs to consumers while addressing these drastic needs effectively and provides a series of charts documenting the investment needs according to replacement of particular piping systems. As water utilities increased their capacity of developing water asset management plans, many water asset managers began to use the AWWA BNL report’s pipe life data as the replacement date for their pipes. This “borrowing” of the BNL report’s service pipe life numbers have increased the risks and cost of many capital budgets. This paper reviews the BNL report assumptions and pipe service life numbers and provides an improved framework and new strategies to more accurately plan for pipe replacement. The BNL report assumes that utilities will maintain the same number of main breaks that occur per mile of pipe. That is, the study assumes utilities will strive to maintain current levels of service rather than allow increasing water service outages. The BNL report assumed that each utility’s objective is to make these investments at the optimal time for maintaining current service levels and to avoid replacing pipes while the repairs are still cost-effective. With this data in hand and using the assumptions above, the report projected the “typical” useful service life of the pipes in the inventory using the “Nessie Model”. The model embodies pipe failure probability distributions based on many utilities’ current operating experiences, coupled with insights from extensive research and professional experiences with typical pipe conditions at different ages and sizes, according to pipe material. The analysis used seven different types of pipe in three diameters and addressed pipe inventories dating back to 1870. Since 2012, many new models and tools have been developed and water utilities assumptions have changed. This paper will review the basis of the 2012 assumptions and provide an overview of new findings which water asset managers should be aware of when developing their water pipe repair and renewal capital plans.

Tarrant Regional Water District (TRWD) and Dallas Water Utilities (DWU) are currently working together to meet growing population demands for water with a new raw water delivery system called the IPL (Integrated Pipeline). The IPL is being constructed of primarily 108” polyurethane coated steel pipe with welded joints for a total distance of 150 miles. The design for the cathodic protection (CP) systems consists of a galvanic system using sacrificial magnesium anodes, with an impressed current system to protect the yard piping at the 450 MG Midlothian Balancing Reservoir. In areas of pipeline interconnect where CP systems and pipe types differ, isolation is required. In these areas, TRWD primarily employs monolithic isolation joints (MIJ) and, to a lesser extent, the more traditional and problematic isolation flange kits. Other CP best practices from the IPL include alternating current (AC) stray current mitigation (a significant safety issue with coated steel pipe), coordination with adjacent third party (oil and gas) CP systems, identification and mitigation of CP system drains such as electric motor valve actuators, and use of buried “smart” reference cells/coupons to obtain more accurate polarized potential readings. During the design phase of the IPL project, the OPT (owner’s project team) was established. The OPT works closely with the CP design engineer, construction management team, and contractor to assist in the inspection, testing, and commissioning of the CP system. Commissioning best practices, including pre- and post- polarization of the CP system and desired polarization ranges for corrosion protection will be discussed.

The vista ridge water supply project includes a 142-mi pipeline that will deliver up to 50,000 acre-feet of water per year from the Carrizo and Simsboro aquifers to the San Antonio Water System (SAWS). The pipeline design included an impressed current cathodic protection (ICCP) system for the 54- and 60-in. diameter concrete, bar-wrapped, steel-cylinder pipe and polyurethane-coated, welded-steel piping. The pipeline was designed to be electrically isolated at the high service pump station, two intermediate pump stations, and the connection point to the SAWS water transmission system. The long alignment presented a number of challenges to designing an effective cathodic protection (CP) system, including determining the current demand over varying soil conditions and pipe materials, mitigating potential current drains associated with the three river crossings and 115 roadway crossings, avoiding conflicts associated with locating CP equipment outside of floodplains and within available easements, and providing flexibility in the design of a system that included over 50 rectifiers and over 700 test stations. This paper will discuss the methods used to overcome these challenges and lessons learned in providing an effective CP system design on a large pipeline.

When do water pipelines need cathodic protection (CP)? Under what circumstances should CP be considered for a pipeline? This decision must be based on the type of pipe product to be used in the proposed system, such as concrete pressure, ductile iron, or steel pipe, their various inherent corrosion-resistant properties, the corrosivity of the surrounding soil, and other important factors. This paper will examine and discuss these various factors and make recommendations as to when and when not to specify CP on a new pipeline. In addition, the advantages and disadvantages of galvanic CP and impressed current CP systems will be examined. The expertise and experience required to design a CP system will be summarized.

The paper outlines a process undertaken to determine the need for cathodic protection (CP) on a new pipe installation. Coating breakdown over time was predicted based on CP design codes. Published data on corrosion of buried or immersed metal samples was reviewed to provide a correlation between ground water chemistry and mass lost. This was combined with probability distributions of corrosion rates used in other corrosion modelling work to produce distributions of corrosion rates for buried metal. The probability that wall thickness would be reduced below that required within the design life of the pipe was calculated and compared with acceptable probabilities of failure contained within design codes. This demonstrated that CP was not necessary on this project, saving both initial capital cost and the associated maintenance liability. An example is also presented showing how this approach can be easily adapted to provide a design life for CP that could feasibly be significantly shorter than the design life of the pipe.

In the summer of 2016, the San Antonio Water System (SAWS) entered into a contract for the delivery 50,000 acre-feet of water from a well field in Burleson County to northern Bexar County by April 2020. The project delivering this water is known as Vista Ridge. Vista Ridge consist of a well field, seven miles of raw water well collection lines, water treatment plant and high service pump station, two intermediate pump stations, and over 140 mi of 54- and 60-in. transmission main. Vista Ridge is a public private partnership (P3) design build project led by Garney Construction (Garney). To deliver water in April 2020, Garney, the design-builder, determined pipe installation must begin no later than Spring 2017. This required multiple crews to work simultaneously. The team had less than one year to design, purchase, manufacture, and deliver the first pipe to the site. Pipe production and delivery continued for 2 years. To meet the aggressive schedule and scale of this project, the design build team worked in tandem with the pipe manufacturer. Five crews working simultaneously installed over 140-mi of 24-in. through 60-in. steel and bar-wrapped pipe in 26 months. This paper presents an overview of what worked and where the team went back to the drawing board, and outlines how they met aggressive pipe design, production and delivery schedules, and remained ahead of construction crews.

This water supply project is an example of a successful private-public partnership. This paper describes the design and permitting solutions, and design-build contracting tools used to meet an aggressive project schedule. This paper will describe the challenges with a concurrent design-build, land acquisition, and permitting process. This water supply will provide over 44-million gallons of water per day from Central Texas to the San Antonio region. The Vista Ridge water supply project is a public-private partnership (P3) with the San Antonio Water System (SAWS). The project included private financing to design and build the new water system. The system will be privately operated for 30 years. The project included extensive design analysis and recommendations to deliver a 44-MGD groundwater supply through a 140-mi transmission main system. The project includes a wellfield with 18 wells delivering raw groundwater to a water treatment plant. The groundwater source is cooled, disinfected, and treated for stability. The water is pumped over 140-miles through a 54- and 60-in. water transmission main. The project includes three (3) pump stations. The project delivery included a fast-paced land acquisition and permitting process. This process occurred concurrently with the alignment design and hydraulics and surge analysis. A methodology for landowner coordination, environmental clearance, alignment, and hydraulic verification was developed for a large design team. The 140-mi pipeline alignment was divided into 16 construction packages that were established for the concurrent construction with five (5) contractor crews. This paper describes a successful approach to designing and constructing a P3 water supply project. The project included close coordination with the public agency during a fast-paced concurrent design and construction project. This included iterative reviews, multi-agency approvals, and a documentation process for field adjustments during construction. The project included a robust construction SharePoint site for facility team members. It also included a computerized maintenance management system (CMMS) design, fiber optic communication and SCADA system, and extensive power coordination with three (3) utility providers over seven (7) counties in Texas.

Design/build/operate projects are generally on an accelerated schedule and due to the added operational requirements encourage coordination between the engineer, contractor, and owner. Effective coordination on these projects will provide a completed project which meets the project schedule and potentially reduces construction costs. Throughout the design build process the engineer, contractor, and owner participate in value engineering processes that necessitate each party to view the problem from the other side to make sure that the final product meets the project requirements.

This paper will focus on the challenges, best practices, and lessons learned from the design of a segment of a major water supply project crossing the 4th largest city in the country. This project includes more than 9 mi of 84-in. steel pipeline as well as some parallel distribution lines ranging in diameter from 36- to 84-in. The first half of the paper will discuss the challenges and approaches to challenges in preliminary design. These challenges and the approach to address them will cover routing of large pipelines in narrow corridors, pipe material selection for several pipe diameters, embedment material selection, preliminary utility coordination, and other stakeholder outreach. The second part of the paper will focus on the critical final design considerations that were evaluated; such as isolation valve placement, transient analysis, testing/disinfection planning, final utility coordination, tunnel design, and agency coordination. This case study will give other engineers and owners a roadmap for accomplishing the design of a project of this size successfully and minimizing the impact to the community without increasing costs to the Owner.

The Central Water Integration Pipeline (CWIP) Project by the San Antonio Water System (SAWS) in San Antonio, Texas, included: three lap-welded steel pipelines totaling 3 miles in length, classified as Segments 5-1, 5-2, and 5-3, with 54-, 36-, and 48-in. diameters respectively; the agua vista treatment plant with steel pipelines and fittings up to 60-in. in diameter; and major improvements to an existing pump station with steel pipelines and fittings up to 54-in. in diameter. The 54-in. Segment 5-1 Pipeline included approximately 8,200 ft of a two-pass tunnel system with five shafts. Minimum wall thicknesses were established by the owner’s engineer for the different pipe diameters based on the internal hydrostatic pressures including full vacuum, joint analysis, and an external grout pressure of 15 psi in case of the tunnel pipe; back-up analysis will be presented. The lap-welded joint details were also established and the adequacy of the single lap-welded joint in non-thrust areas and tunnel liners was checked based on ASME, AWS D1.1 codes and joint stress analysis; analysis results will be presented. However, in thrust areas of bends, the first joint at either end of the bend was mandated to be double lap-welded due to the additional bending stress at the first joint due to the bend movement against the soil. A summary of the preliminary designs conducted and lap-welded joint details will be presented. Regarding the steel fitting reinforcements, the project specifications mandated the use of crotch plate reinforcement at equal diameter tees at critical locations which will be discussed. The project specifications required the successful bidder to perform the steel pipe and fitting designs in conformance with AWWA M11 manual and per the project specification requirements. In addition, analysis was required for the horizontal and riser pipe in the tunnel shafts which will have flowable fill backfill up to 86 ft deep. A summary of design checks and procedures used will be presented.

The Tarrant Regional Water District (TRWD)’s Kennedale Balancing Reservoir (KBR) bypass pipeline project included four 108-in. tees, two 30-degree 108-in. by 108-in. wyes, and several 108- by 30-in. tees, all of which were steel fittings. The wye fittings failed during hydrostatic pressure testing due to excessive localized stress, excessive strain, cement mortar lining, and concrete encasement failure. The tees showed no signs of failure. The fittings were originally designed with crotch plates per the Fourth Edition of the American Water Works Association (AWWA) Manual of Water Supply Practice M11 (M11) guidelines. However, an option to design the fittings with the American Society of Mechanical Engineering Boiler and Pressure Vessel Code (ASME-BPVC) section VIII, where suitable, was allowed in the specifications. The ASME-BPVC was allowed because it reduces the cost and the size of the fittings. The ASME-BPVC was selected for final design and fabrication of the fittings by the pipe manufacturer to reduce cost and because they believed the 30-degree wye with crotch plate was not constructible. After the initial hydrostatic test failure, finite element analysis (FEA) from two separate entities, and a FEA review from a third entity revealed that the ASME-BPVC design resulted in excessive localized stresses and strains for the wye fittings. After the failed field weld was modified, the wye fittings were able to hold pressure briefly during a “Proof of Design” test requirement allowed by the ASME-BPVC, but the wye fittings deformed, causing the ground to heave and the lining and encasement to crack. The original wye fittings were replaced with new fittings based upon the M11 design, and verified by FEA, which successfully passed the hydrostatic testing. The ASME-BPVC has been used successfully for design of steel water pipe tee fittings; however, this project revealed that the design procedure may not be suitable for all wye fittings, especially with large diameter openings and if cement mortar lining is used because it limits the allowable deformation. This paper compares the M11 and ASME-BPVC design procedures and proposes limitations on the application of the ASME-BPVC design procedure for large diameter steel wye fittings.

The San Antonio Water System (SAWS) entered into a contract with Vista Ridge LLC to provide 50,000 acre-feet per year of Carrizo/Simsboro Aquifer groundwater to meet the growth needs and to diversify the water supply of San Antonio. As part of the Central Water Integration Pipeline (CWIP) Project, modifications to the SAWS system are required to convey finished water from the new treatment plant at the Agua Vista Station to the existing SAWS system. The CWIP project includes a treatment plant, pipelines, pump stations, concrete tanks, pressure reducing stations, and rehabilitation of SAWS existing tanks. Finished water will either be pumped out of the Agua Vista Station through the new Stone Oak Pump Station or flow by gravity to the downstream facilities. This paper focuses on the planning and design of one of the new water transmission pipeline segments: the segment 5-1 pipeline contract. This portion of the project consists of 10,300 linear feet of 54-in. welded steel pipeline. Several challenging design aspects had to be undertaken in order to meet the aggressive project schedule including selecting a pipeline alignment, providing trenchless construction for over 75% of the alignment, and determining the steel pipe design criteria.

Large diameter transmission pipelines are critical infrastructure that, within more arid areas of the country, must traverse long distances to bring water to the communities that need it. As the state of Colorado continues to grow and develop, the open and rural spaces between population centers tend to have more critical wildlife habitat and environmental protections. While these rural areas can be prime pipeline corridors, consideration, and planning is necessary to successfully construct a pipeline when endangered species and environmentally sensitive areas cannot be avoided. Northern Colorado Water Conservancy District (Northern Water) is building the Southern Water Supply Project II (SWSPII)—a large-diameter raw water regional pipeline project over 20 mi in length through Larimer and Boulder Counties in Colorado. The 36-in diameter steel pipeline will provide raw water to four (4) different public entities. Routed through multiple endangered species habitats, protected prairie dog colony land, and other protected raptor species nesting zones, this project has unique design, permitting, and construction challenges. During the design phase of the project, an inventory of all wildlife impacts and associated schedule constraints was developed. Multiple raptor surveys, Preble’s Meadow Jumping Mouse habitat surveys, wetland delineations, and prairie dog counts were completed. Different raptor, wetland, and prairie dog protocols for the four (4) different jurisdictions in the pipeline’s path were evaluated and documented. In addition to wildlife schedule constraints, a variety of farming and irrigated land impacts and schedule limitations were prevalent on the project. A detailed list of all these constraints were provided to the contractor during the bid phase of the project. As construction on the project began in Summer 2018, it was clear the project could not proceed in a linear fashion from one end to the other. Timing the work with the variety of constraints and timelines, as well as bird nesting changes, proved very challenging. This paper will describe the challenges, construction approach, and lessons learned to both plan and construct large diameter pipelines in environmentally sensitive areas with detailed schedule constraints. Some elements to be discussed include the following: allowing time for all construction activities, testing, and contingencies; best practices for minimizing impacts in wetlands; expediting construction when needed; and getting Contractor buy-in on schedule.

A discussion of an extensive route analysis for approximately 17 mi of 48-in. water transmission line in Caldwell County. Discussion will include data collection, alignment considerations, and lessons learned from route analysis which reduced the total pipeline length by ~20%, estimated construction costs by ~20%, and easements by ~63%.

When projects require direct buried installation of large butterfly valves, special installation, factors must be considered to maintain valve integrity, and prevent damage to the pipeline. In response to a request from AWWA’s steel pipe and stainless-steel pipe committee chairs, a task force on large valve installation meeting was first held at ACE17 in Philadelphia to discuss the issue of valve deflection; since then the committee has had multiple meetings and, most recently at ACE19, the task force discussed additional mitigating solutions to limit loading of valves by thereby controlling deflections. One of the solutions proposed by the AWWA task force committee was the addition of grooved, flexible yet restrained couplings on either side of the valve. This paper will address the benefits of the addition of grooved, flexible yet restrained couplings, located on either side of the large butterfly valves belowground. Piping stress analysis, using CAESAR II software that utilizes an FEA analysis using beam elements with 6 degrees of freedom at each node, was performed on 24”, 48”, 72”, and 96” steel pipe sections subject to a rigid restraint on the left, a guided restraint on the right near each side of the valve, 100 psig water pressure, and a 2” vertical displacement. The moments on the fixed end (valve end) were calculated with and without pairs of flexible couplings. When couplings were used, the moment on the valve was reduced by about two-thirds when compared to the case where pipe was installed without couplings.

Over the past several years, Denver Water has been working to improve the reliability of its northern supply system which makes up large portion of its water portfolio. The Moffat collection system, originally constructed in the 1930s, is the beginning of this system and includes a series of canals, tunnels, and pipelines to collect and convey snowmelt runoff from the Colorado mountains to the Denver area. A critical component of this collection system is a 72-in. diameter aerial pipeline known as the Siphon 1 Fraser River Crossing. The aerial crossing and its approach is located on steep slopes at the base of the Winter Park ski area adjacent to a railroad track and tunnel, and crosses two primary access roads, numerous utilities, and a gold medal trout habitat. Based on assessments of its age and condition, Denver Water determined that this aerial pipeline needed to be replaced for continued, long-term reliability. Due to the site location, conditions and aerial installation, as well as the numerous stakeholders and short construction window, the project was not a straightforward pipeline project. This paper presents the technical and coordination challenges related to the successful design and construction of this critical, high-profile aerial pipeline replacement.

A 1 km (~3,300 lf) long section of the North York Stormwater Trunk Sewer (STS), a 3,000 mm (118”) diameter corrugated metal pipe that services approximately 800 ha in Toronto, Ontario, has sections that are in poor condition to near failure and needs timely repairs. The culvert was built along an existing tributary to Black Creek, which resulted in a highly irregular alignment, that includes frequent sharp vertical bends and horizontal sweeps. Additionally, the culvert was constructed in several phases over a period of approximately 20 years as a result consists of multi-plate and CMP products lined with various products (tar, shotcrete, and concrete). This paper will summarize the design phase of the project to rehabilitate the deteriorating sewer, which included selecting the optimal rehabilitation methods, and producing designs and implementation plans to suit the site conditions and pipe geometry.

Metro Vancouver is the regional water supplier for the greater Vancouver area [British Columbia (BC), Canada], responsible for providing drinking water to 2.5 million residents. Regional growth, and resilience and maintenance needs, in the next decade require over 90 km of new, large–diameter watermains, with many likely to be constructed in a highly urbanized environment. Metro Vancouver’s Kennedy Newton and Annacis Main No. 5 South project involves the design and construction of 11 km of 1,829-mm-diameter, welded steel transmission main. The watermain will connect the proposed 3.5-m Annacis Tunnel Crossing South Shaft to Kennedy Park and Newton Reservoirs. Most of the pipeline alignment is inside a road right-of-way and runs through residential areas, business corridors, and arterial roads. Challenges (and opportunities) are associated with designing large watermains in urban areas. This paper presents a case study of the challenges as they relate to Owner, Engineer, and Project stakeholders. It also describes the solutions that allowed completion and acceptance of the design by internal and external stakeholders.

This paper will focus on engineering controls where implementing best practices in design can have significant impacts on large diameter pipeline safety. The engineering controls include route selection, material selection, specialty fittings and pipeline configuration, trench safety, and pipeline access. The guiding principles of safety in design are founded on implementing engineering controls early in the design process to eliminate or minimize risks throughout the life of the pipeline being designed. The controls begin with hazard identification, considering who will use the facility, who will build it, and who will maintain it. This paper will discuss pipeline route selection, including critical crossings and proximity to existing and future infrastructure and communities; the benefit tradeoff for material selection for the pipe, bedding, backfill, and stabilization; fitting configuration, including considerations for complex or large fitting arrangements, manholes, and occupational safety and health administration (OSHA) requirements for significant trench depth; depth of cover for protection of the pipeline, trench safety, and proximity to static and dynamic loads; and pipeline access, including spacing between access manholes, maximum pipe slope, isolation valves, and dewatering. This paper will present sample case studies to help illustrate some of the aspects of safety.

In response to nearly 20 years of drought conditions and declining water levels in Lake Mead, the Southern Nevada Water Authority (SNWA) has constructed a new Low Lake Level Pumping Station (L3PS) and new discharge aqueducts to convey the water to their existing water treatment plants. The two 144-in. diameter discharge aqueducts needed to extend under a 45-ft high causeway embankment. Traditional analysis methods referenced from the American Water Works Association and the United States Bureau of Reclamation sources resulted in very costly trench and backfill methods for this deep pipe cover. A further analysis of external loadings beyond the traditional methods was warranted. To streamline the construction schedule, reduce risk, and reduce construction costs, a two-dimensional finite element analysis was preformed to better predict the deflection of the aqueducts through the causeway. Several simulations were run, along with sensitivity studies, to determine how the pipe zone material properties would impact the deflection and determine the best overall design. Detailed field measurements were taken during construction to assess the accuracy of the assumptions and calculations. This paper presents the traditional and non-traditional design of these 144-in. diameter pipe sections, with results of actual field conditions.

Approximately 16 mi of 108-in. diameter water transmission main is being constructed across northeast Houston to supply various regional water authorities to meet their projected 2060 water supply demands. Historically, the city of Houston has installed butterfly valves for isolation in large diameter water transmission mains. Typically, the City of Houston requires the butterfly valve to be connected to the pipe via flange and bolts and the assembly supported with bank run sand embedment. Butterfly valves have been a constant maintenance concern for the City’s operations department for a variety of reasons. Recent studies have indicated butterfly valves cannot be fully closed if the adjoining pipe is deflected over 1% of the diameter. The city allows a maximum deflection of 3% which can be problematic for a butterfly valve. Therefore, special design considerations were implemented for the proposed 108-in. pipeline project. The adjoining pipe was designed to ensure the pipe and soil loading would not negatively affect the integrity of the valve. Pipe wrappers and saddle supports were designed to keep the pipe from deflecting. The steel wrappers not only provided stiffness to the pipe, but also assisted with supporting the pipe over the concrete saddles. The load is then transmitted to the concrete foundation. Many factors were considered in the design of the support including soil loads, valve weight, water weight, and associated pipe loads. A flowable fill material is proposed as the embedment material to proper support for the pipe and valve. Future maintenance was also considered in the design of the valve. The seat was designed to be mechanically retained to allow for the seat to be field repaired in place rather than remove the valve entirely. A vault was designed to allow for future access of the worm gear actuator and packing. The concrete foundation extended under the pipe saddles and the actuator vault to avoid differential settlement issues. Six butterfly valves have been installed according to the revised detail and are operating as designed.

The Sabine River Authority of Texas (SRA) saved approximately $1 million by competing prestressed pipe and steel pipe for their new 66-in. diameter pipeline. The project team received bids for the pre-purchased material and evaluated the anticipated install price. The evaluation compared different embedment materials, installation methods, and material costs to estimate the ultimate construction cost of the pipeline depending on the pipe material. Ultimately, prestressed pipe was expected to cost less. Using the SRA project as a case study, this presentation will instruct audience members the advantages of alternate bids, steps to create more competitive material procurement, and factors to consider when evaluating options.

As with most growing cities, the City of College Station is faced with critical decisions on how to plan for an ever-increasing load on their existing WW collection system and how these increasing flows will affect the operations of their two WW treatment plants. The lick creek parallel trunk line project addressed the challenges of designing a trunk main to handle future peak flows and routing it through a private golf course and a City park. This presentation will teach municipal utility personnel what factors to consider when designing and planning large-diameter sewer mains within highly sensitive areas.

A condition assessment performed in 2014 identified two valve houses on either side of a below grade crossing of the Houston Ship channel by three 60-in. steel water lines in need of improvements, as well as some other issues with the existing water lines. Lockwood, Andrews, and Newnam, Inc. (LAN) was tasked with preparing a design to rehabilitate the raw water line, and structures. Rehabilitation included asbestos abatement and demolition of both valve houses, installation of new valve houses, rehabilitation of above grade pipe coatings, encasement of deflected pipe segments, and installation of sacrificial anodes. With the project reaching completion in 2019, the City of Houston now has two new structures to house the above grade valves and pipelines, rehabilitated coatings, and restored a 60-in. water line to service that had remained out of service for over 15 years.

Several studies have confirmed that many of the lateral pipes in typical collection systems have reached their life expectancy and are either failing and/or contributing large amounts of infiltration and/or inflow (I/I) to the main sewer pipeline. In response, technology providers developed a number of products and technologies to line and seal lateral pipes and their connections to the mainline sewer. Lateral pipes often have multiple bends, diameter changes, offset joints, cracks, deposits, and roots, which create considerable challenges when lining or sealing. The lateral pipe connection to the sewer main also poses problems due to leaks, cracks, and poor alignment often created by improper connection procedures. Trenchless rehabilitation can address these issues while minimizing the impact to property owners and sewer providers. These technologies also provide an effective service life through proven, tested materials, and refined installation procedures to meet owner expectations.

This paper addresses longitudinal design aspects associated with gravity-flow and pressure pipe lining applications and their impact on product selection and performance. Current industry standard design methods are predominantly based on hoop performance while longitudinal checks are limited to the axial direction without consideration to bending. Information will be presented on projects where cured-in-place pipe (CIPP) was utilized and longitudinal bending due to frost heave, expansive soils, and settlement occurred. Demonstration testing utilized to determine design limitations, recommended repair methods, and subsequent recommendations on future projects will also be discussed.

As more so-called geopolymers are being introduced to the market place, we believe it’s time to have an intelligent and informative discussion regarding geopolymer application best practices: Why: Over the last decade, geopolymers have become a cost-effective and environmentally responsible structural rehabilitation solution, as well as being a viable addition to established materials and processes. What: When discussing geopolymers, the first step is to recognize there is no nationally accepted definition. The definition provided in this presentation is based on generally accepted terminology. The testing to differentiate a geopolymer from cementitious and other similar materials must include analytical procedures other than standard ASTM physical properties. For a geopolymer to be properly defined, both the oxide content (the individual components) and the phase content (the final product formed) need to be determined. When: Geopolymers are often used when pipes are highly deteriorated, exhibit high ovality, are non-round by design, or where there are changes in size, shape, or material in a single pipe length. Geopolymers are especially well-suited for highly corrosive environments and work extremely well in storm infrastructure due to their abrasion resistance. Geopolymers also respond well industrial settings, where flow concentrations and temperatures are of concern. Where: Large diameter (30-in. and larger) projects that can alternatively consider: dig and replace, CIPP, slip-lining, and other trenchless technologies. In many instances, a geopolymer liner works in conjunction with CIPP and similar technologies, addressing segments which otherwise are impassible due to obstructions, direction changes, etc. Who: Owners benefit from having access to this proven technology when structurally rehabilitating storm, sewer and raw water pipe, and infrastructure.

The City of Loveland (City) elected to utilize a Construction Manager at Risk (CMaR) delivery method to help with the planning, design, and construction of two critical pipelines to serve the City’s growing population. Development in the northwest part of the City is projected to exceed the capacity of the existing interceptor and transmission pipelines with pending future developments. A $5.5 million 24-in. diameter PVC interceptor and a $3 million 30-in. diameter PVC transmission line were designed and constructed as a part of this project to increase capacity within the distribution and collection systems. This paper discusses the challenges faced during the planning, design, and construction of the pipelines and how the CMaR was used to streamline decisions, reduce risk, and overcome obstacles including: (1) combining various City Department projects to limit impacts to residents; (2) early out construction package to avoid costly trenchless construction and maintain schedule; (3) construction phasing to navigate tight alleyway installation; and (4) evaluating alignments, materials and construction techniques to meet available budget. As a result of early identification of the technical challenges and the collaborative efforts of the CMaR, Engineers, and City staff (Project Team), solutions were developed that satisfied all of these challenges and allowed the project to meet schedule and be under budget.

Given the importance of watermains in supplying safe and quality drinking water to customers, municipalities are required to ensure that the distribution mains are performing at certain pre-defined levels of service (LoS). In North America, the majority of watermains are made of ferrous materials, typically ductile iron (DI), and cast iron (CI) pipelines. These assets are prone to deterioration and breaks due to aging and other influencing factors, including corrosion. Annually, municipalities confront several constraints related to budgets and the proper time to intervene to preserve water distribution mains. With the significant municipal budgets required to rehabilitate or replace assets with newer pipelines, municipalities should be focusing on prioritizing interventions based on the likelihood and consequence of failures. Besides risk assessment frameworks, optimized programs need to be developed to maximize performance while minimizing the overall funding requirements in order to maintain sustainable funding levels and infrastructure in both the short- and long-term. Therefore, the main objective of this paper was to develop a decision-support system based on the genetic algorithm (GA) optimization tool. The tool considered maximizing the network performance and minimizing the total costs during a 5-year study period. After implementing the model on part of the Municipality of Thames Centre’s ferrous network, the total required cost attained was $434,282, and the performance of the network was restored to approximately 28 out of 100. The total costs of the major intervention (structural lining) and the minor intervention (cathodic protection) were $402,603 and $31,678, respectively. This study will benefit municipalities in developing optimized rehabilitation/replacement programs considering typical municipal constraints while maximizing the existing performance of the network and minimizing the total costs.

The Southern Delivery System Project for Colorado Springs Utilities (Utilities) consists of three pumping stations that deliver raw water supply from the Pueblo Reservoir to the Colorado Springs Edward W. Bailey Water Treatment Plant through 50 m of 66-in. diameter pipeline. The Juniper Pump Station is located at the Pueblo Reservoir and takes supply from the joint use header connecting through the dam and pumps it north to the Williams Creek Pump Station located south of Security-Widefield. Water supply is then pumped north to the Bradley Pump Station located within Colorado Springs and, in turn, pumped north and west to the new water treatment plant. Shortly after going into service, the Williams Creek Pump Station began experiencing unexplained flow instabilities. The flow fluctuation was observed as continuous speed changes generated by the automatic control systems to maintain an average pumping rate during low flow operations. The fluctuations were unanticipated and of a cyclic and intermittent nature, not always present. They were also not observed at the adjacent pumping stations within the system making the problem difficult to diagnose and solve after the most obvious potential causes, such as erratic meter readings or stability adjustments to pump speed algorithms, were ruled out. The owner was concerned about potential long-term equipment impacts, the effect on energy efficiency and long-term operational costs, and possible larger issues that could develop in the future with increased flow demands. The design consultant was requested to assist utilities in resolving the issue which involved a multi-disciplinary team of individuals represented by the designer, general contractor and subcontractors, SDS management team, and utilities operations. Investigations are described below with discussion of the final conclusion, range of solutions explored, and the selected operational changes implemented.

According to the Federal Highway Administration of the U.S. Department of Transportation, there are more than 4.1 million miles of road in total length, making it the world’s longest and biggest road network with millions of culverts hidden underneath road in the United States. Trenchless technologies rehabilitation employ innovative methods, materials, and equipment that require minimum surface excavation and access. Trenchless technologies can be used when other conventional methods, such as open-cut methods are not applicable or cost-effective. Life-cycle cost analysis (LCCA) is an analytical method used to evaluate long-term investment options, and facilitate the associated costs which consists of three main modules as construction, environmental, and social costs. The objective of this paper is to develop a framework for LCCA for trenchless renewal methods for large diameter culverts and to identify and categorize the potential factors which contribute to LCCA with the help of literature review. It is found that host pipe length and diameter, rehab material, rehab thickness, and rehab design life were the key factors to construction cost. Also, material components, volume of materials, material transportation, project duration and location, and installation equipment were the main influencing factors to environmental cost. Last but not least, study shows that the location and duration of the project, type of traffic control, traffic peak, average annual daily traffic (AADT), pavement restoration cost, and noise indicator were the major potential factors to social cost. It can be concluded that many quantifiable factors are involving to have comprehensive evaluation of LCCA as an essential element when considering trenchless renewal of large diameter culverts. This framework can be utilized to evaluate LCCA in large diameter culverts for different trenchless renewal projects.

With recent population increases and projected growth in the North Texas area, available drinking water during drought conditions is a growing concern for water providers. In conjunction with Dallas Water Utilities (DWU), HDR evaluated alternatives to identify the best apparent method to convey 150 MGD of raw water to the Bachman Water Treatment Plant (WTP) by 2027 for drought prevention and to meet water supply requirements in North Texas. Early stages of the project involved HDR and DWU identifying ten alternatives for preliminary evaluation and developing non-cost evaluation criteria and weights for the comparison and scoring of alternatives. Benefit scores and planning-level costs were input into the cost-benefit decision tool to facilitate decision making and provide justification for the path forward. By applying the cost-benefit approach, the five most favorable alternatives were identified for further evaluation. A hybrid of two alternatives providing additional blending benefits, phased construction, and operational flexibility was also developed and included for consideration. Final evaluation of alternatives resulted in selecting the hybrid alternative, which initially included a phased implementation and involved approximately eight miles of open lake conveyance and 22 mi of up to 96-in. diameter hard-pipe conveyance, as the best conveyance method. Future project phases would require additional pipeline and a pump station. After refining the hydraulic analysis for this alternative, the project team determined that the pipeline diameter could be reduced to 90 inches; and with additional tunneling, the full 150 MGD could gravity flow to the Bachman WTP, eliminating the need for future project phases. HDR is finalizing the preliminary design on the selected alternative that includes an Implementation Plan to assist DWU with project delivery and phasing, staffing, permitting requirements, property acquisition, and project funding.

Due to a severe drought, the Metropolitan Water District of Southern California (MWD) was concerned the Mills Treatment Plant would not have a sufficient supply of water for 1,000,000 people. To alleviate this situation, MWD decided to connect the Inland Feeder and Lakeview pipeline so water could be delivered to Mills from Diamond Valley Lake. This interconnection connected the Inland Feeder, Lakeview Pipeline, and the Lake Perris Control Facility (LPCF). The LPCF is used to control flow in the Lakeview pipeline and was designed for significantly lower pressure than Inland Feeder. MWD originally planned to protect the PCF using two strategies: bypassing the LPCF under certain flow conditions and using a pressure relief system in other flow conditions. MWD evaluated the facility, its current and future operation, and the pressure relief options to determine the best solution. This paper discusses the methodology used to select the best alternative; discusses the importance of considering: current and future operations; how to evaluate alternatives in complex facilities; and the importance of considering long-term benefits when making facility improvements.

Repeated excavations of buried utilities cause road congestion, maintenance conflicts, and subsequently increase social costs. An alternative of burying utilities is hosting them in a multi-purpose utility tunnel (MUT). MUTs reduce the excavation needs and provide easy access for all year-round inspection and maintenance for utilities. MUT planning is a key factor of urban underground space planning. Previous research focused on MUT technologies; however, few papers focused on MUT planning. Location selection for MUTs is an important phase for MUT planning and it is complicated because it depends on several criteria. This paper provides a general method for MUT location selection at different urban scales using geographic information system (GIS) and multi-criteria decision making (MCDM) for the selection of potential MUT locations. The weights of the criteria are calculated using the analytic hierarchy process (AHP) method. A case study is used to demonstrate the feasibility of the proposed method.

Poseidon’s Carlsbad Ocean Desalination Plant requires a new intake to meet California’s Ocean Plan Amendment (OPA) requirements. To do so, a subsurface series of wedge wire intake screens located approximately 900 ft off shore within the Agua Hendionda Lagoon is required. This presentation will review the design considerations necessary to make intake lateral number, size, material, and construction method decisions. None of these criteria could be determined independently, as they all have implications to each other as this paper will explain.

In most linear water line projects, the design and construction process follows a logical, systematic approach of solidifying a route via land acquisition, finalizing engineering plans based on that secured route, and then using the finalized plans to build the project. The obvious benefit to this process is that it reduces the risk associated with various costs that may stem from changes in the route such as re-engineering, unusable material purchases, and retrofitted construction work. The flip side to this conservative approach is that it requires time to develop. This restriction is most evident in long, linear projects where the greatest uncertainty in the process is land acquisition. This uncertainty becomes more complex to manage as the number of affected landowners increases. This paper presents a case study in how to manage a long, linear project within an extremely short delivery schedule without relying on condemnation to acquire land.

To address the challenge of population growth coupled with aging infrastructure, the City of Alvin, Texas, is embarking on its largest wastewater collection project ever: consolidation of two parallel trunk sewers into one 54-in. interceptor. Using this project as a case study, this presentation will give owners more tools in their toolbelt to improve the condition and increase the capacity of their wastewater collection system, minimize impact to their residents, and reduce capital and maintenance costs to their ratepayers. The City of Alvin has a single wastewater treatment plant (WWTP) that collects wastewater through two parallel trunk sewers (27- and 33-in. diameter). These pipes, installed in the 1960s and ’80s, show signs of increased deterioration and are at capacity to serve current demands. The City’s wastewater master plan identified a 54-in. trunk sewer, known as the Eastside Interceptor, to replace the existing parallel sewers. But rerouting sewer lines poses multiple hurdles, especially when a key goal is minimizing the disruption for residents. Sewer collection systems are built around the current location of the trunk sewers, but a reroute means redirecting the existing collection system to a new alignment. Alvin’s planning and design teams evaluated three different routes to reduce impacts to City residents. Using the City’s wastewater model developed as a part of the wastewater master plan, to evaluate up and downstream hydraulic impacts of each route alternative provided a dynamic analysis that allowed the City to choose a route based on a solid understanding of the construction and hydraulic implications of each option. Innovative design approaches addressed multiple challenges for the Eastside Interceptor. First, utilizing the existing sewer lines for reduced bypass pumping requirements reduces the bypass burden on the contractor during construction. Since there are existing parallel trunk lines, flow could be diverted into one trunk line and reduce pumping capacity necessary to replace the sewer lines. Additionally, a combination of rehab technologies will allow the selected alternative route to still convey wastewater through the existing sanitary sewers until they intersected with the new Eastside Interceptor.

To comply with a mandated 80% reduction in groundwater extraction in Houston, the West Harris County Regional Water Authority is constructing the $1.2B surface water supply project. This project includes three steel pipeline crossings of growth faults. Two of these crossings are 96-in. in diameter and the third is 84-in. in diameter. These crossings rely on strain-based design to accommodate large permanent ground deformations. Guidelines for constructing natural gas and liquid hydrocarbon pipelines through areas prone to landslide and subsidence hazards (PRCI 2009) and other similar standards were used as guidance for the development of the design. The specified pipe materials are based on AWWA C200 Steel Pipe, 6 In. (150 mm) and Larger with minor modifications to meet the additional requirements of strain-based design. Specifications were developed to utilize AWWA steel pipe materials, standards and practices where acceptable and supplemented with addition requirements and testing necessary for stain-based design. Additionally, the project is evaluating allowing contractors to use proprietary steel joints designed to accommodate bending and tension.

The evaluation of welded steel pipe and pipe joint strength for resisting seismic forces is essential to establishing the design basis for today’s conveyance infrastructure. Unfortunately, little information is available for large diameter, thin wall, spiral welded steel pipe which is commonly used in the water and wastewater industry. As a result, pipeline designers will often use information tailored to other industries such as steel buildings and off-shore drilling structures which may not be relevant to welded steel water pipe and the use of this information could lead to unconservative results with questionable seismic resilience. The effects of internal pressure are known to augment the strength of welded steel pipe and joints however accurate test data suitable for design use is currently unavailable. This paper describes a planned testing program that will include physical tests to evaluate the strength of welded steel pipe, field welded joints, and mechanical joints under pressurized and non-pressurized conditions. The goal is to develop an understanding of how typical, large diameter steel pipe will perform when subjected to bending, tension, and compressive forces which are the basis of seismic resilience.

Ever since the 1995 Kobe Earthquake, earthquake damage to buried pipelines due to fault movement, liquefaction, land settlement, and the like has been seen in large-scale earthquakes. After a large-scale earthquake occurs, restoration of the main water pipelines is considered a priority, but this is time consuming when large deformations and water leakages occur. The steel pipe for fault (SPF) settlement type was developed to absorb ground displacement and prevent water leakages at connections in ground structures and buried pipelines in order to maintain water flow without cracks, even if ground settlement occurs. The development of this SPF is based on the technology of the SPF original type, which is a solution for infrastructure and pipelines in fault zones.

Buried pipelines are susceptible to damage from large ground displacements imposed by natural hazards such as earthquake-induced fault rupture, landslides, and liquefaction-induced settlements and laterals spreads. A significant percentage of water and wastewater networks are composed of segmented pipelines that are particularly vulnerable at the connections linking adjacent lengths of pipe. To address susceptibility to ground movement, new pipeline systems, with improved materials and jointing mechanisms, have been introduced into the market, some of which have had their seismic performance assessed through full-scale testing. This paper provides a framework for the interpretation of results from full-scale experiments designed to evaluate the transverse response of pipelines and connections under lateral loading. A series of four-point bending tests on thermoplastic pipelines with various connection types are discussed to illustrate lateral response mechanisms of traditional continuous and segmented systems, as well as pipeline connections that exhibit combined behavior. Displacement and strain measurements that capture simulated pipeline response to ground movement perpendicular to the pipe axis are employed to calculate key response metrics, namely joint deflection, pipe curvature, radius of curvature, and applied moment. The presented procedures provide guidance for characterizing transverse response relative to the seismic classification currently under develop in the 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.

A series of analyses were completed to evaluate the maximum stress and strain in a pipeline as it experienced an increasing amount of seismically induced differential settlement. These analyses allowed the development of tables for use by pipeline designers that specify the pipe wall thickness and joint type required to accommodate the anticipated differential settlement over a specified length without completing location specific analyses. The finite element software Abaqus was used to evaluate the stress and strain levels in the pipeline as the magnitude of seismically induced differential settlement increased. The maximum stress and strain reported in the pipeline model was compared with allowable limits for butt-welded and lap-joints for a range of pipe wall thicknesses. This analysis was completed for 48- and 60-in. diameter pipes and considered pipelines bearing directly on liquefiable soil and pipeline embedded in a non-liquefiable soil “crust” overlaying a liquefiable soil.

There is a crucial need for an effective model that can maximize the seismic resilience enhancement resulted out of every dollar spent on the seismic rehabilitation of water pipe networks. Hence, this study was carried out with an objective of identifying economical seismic rehabilitation policies, for water pipe networks, using a hybrid metaheuristic optimization model. The hybrid metaheuristic optimization is based on the combination of simulated annealing and genetic algorithm. The solution identified by the hybrid metaheuristic yields water pipe rehabilitation policies that lead to maximal post-earthquake network serviceability under given rehabilitation budget constraints. The proposed model was tested on a city-scale pipe network. The comparison of the results produced by the current model with the results from a latest model in literature validates the effectiveness of the proposed model in identifying economical seismic rehabilitation policies for water pipe networks exposed to significant seismic risks. The proposed optimization model is expected to help many utility managers in significantly enhancing the seismic resilience of water pipe networks that are highly susceptible to severe serviceability loss due to earthquakes.

Due to deteriorating pipeline infrastructure, approximately 20% of treated drinking water is lost during distribution before reaching water taps in many neighborhoods. The available leakage detection techniques are able to find leaks but require skilled labor and prior knowledge of the leakage proximity. This study discusses a deep learning model to automatically detect leakages based on flow-induced vibration signal data of water pipelines. The main objective of this study is to discuss an unsupervised classification technique to collect vibration signals and categorize them into non-leaky or leaky classes. A two looped experimental polyvinyl chloride (PVC) pipeline network, which comprises of a pump, a reservoir of 820-l capacity, varying pipeline diameters, burial conditions, various bends, T-joints, leak simulators, and a flowmeter, is used to evaluate the envisioned deep learning approach. Six accelerometers are attached to pipelines across the experimental testbed to capture flow-induced vibration data for non-leaky and leaky configurations to prepare the signal database. These vibration signal data were converted into image format using continuous wavelet transformation (scalogram) plotted as a function of time and frequency. The scalogram images can be used to train and validate an unsupervised classification model. The performance is evaluated using accuracy, recall, precision, and F_Score measures. Eighty percent of the data in the signal database is proposed to be used for training whereas the remaining 20% is to be used for testing. This paper presents the latest outcomes of this research effort by primarily highlighting the methodology and challenges faced.