Pipelines 2019: Condition Assessment, Construction, and Rehabilitation

The scope of this presentation will include the condition assessment of approximately 12,000 linear feet of existing 72-inch RCP interceptor built in 1963 and the evaluation of rehabilitation alternatives. The presentation will also include the design of the recommended alternative, bid results, and lessons learned from construction. The existing 72-inch RCP main was initially constructed with a PVC liner to protect the concrete from corrosion, but over time, portions of the liner detached from the concrete and the main experienced corrosion. Two point repair methods were designed to repair the corrosion and restore a protective liner to the detached locations. The two methods included a fiberglass liner and an epoxy liner with details and specifications for each. Each of the point repair methods will require flow diversion and man entry for installation by hand. Construction began in November 2018 and is anticipated to be completed in May 2019.

What happens when you determine one rehabilitation technology isn’t sufficient enough? The internal or external rehabilitation of aerial piping can be a tricky concept when utilized as an either/or repair option, but when combined, these technologies can prove to complement one another and provide a fully structural repair solution not previously considered in our industry. For a municipality in North Texas, they are no stranger to this design challenge, but they had never considered the combination of these technologies until it was presented as one design solution procured under one contract. By consulting with their partners, they realized that this problem could be overcome by implementing both an internal and external repair solution. This paper will focus on two aerial pipes, 12-inch and 18-inch steel pipes, which were showing signs of severe deterioration. The design team determined that the pipes would be internally rehabilitated with cured-in-place pipe (CIPP) to eliminate internal corrosion; then, to provide additional protection due to environmental exposure and provide additional longitudinal strength, the use of carbon fiber reinforced polymer (CFRP) systems was designed to be applied to the exterior. This paper will discuss the city’s struggle with this issue and the process that led to this unique repair option. The design procedures and the construction details will also be discussed and illustrated.

The Coastal Water Authority (CWA) is a raw water provider created by a special act of the 60th Legislature of the State of Texas in 1967. CWA provides approximately 1 billion gallons per day of untreated surface water to Houston and the surrounding area. In the winter of 2016, an internal condition assessment of a 60-inch prestressed concrete cylinder pipe (PCCP) pipeline revealed significant distress based on visual cracking and wire break data in a single 16-foot long pipe segment, which was rated at high risk and required either replacement or a fully structural repair in an area that would not permit excavation. This paper presents the assessment methods, findings, and details about an internal carbon fiber repair.

The Virginia Tunnel is a 5,400-foot sewer that is 78 inches in diameter and 80–100 feet deep. Constructed in 1963, this asset is part of the Potomac Interceptor and conveys flow from the Dulles Airport and portions of Loudon, Fairfax, and Montgomery Counties to the DC Water Blue Plains Wastewater Plant. Based on CCTV and sonar inspection data, the tunnel has exhibited corrosion and deterioration. An initial assessment of this inspection data identified the pipeline as a high priority for rehabilitation. Rehabilitation design was initiated, but due to numerous challenges, including site access, maintenance of flow, capacity requirements, and depths, the project was never constructed. A fresh review of the project identified that the perceived risk of failure may have been overestimated. The project team utilized innovative inspection techniques, including CCTV/sonar/laser/3D lidar and pipe penetrating radar to re-evaluate the structural integrity of the sewer in tandem with a geotechnical assessment. This evaluation allowed the team to properly assess the tunnel condition and associated risk. This presentation will present the project background and the pitfalls of standardized defect coding that contributed to the tunnel vision in the identification of rehabilitation alternatives. The paper will provide a case study in how inspection strategies, when properly applied and evaluated, result in higher resolution data from which to effectively assess risk and identify appropriate solutions that may result in significant cost and schedule savings.

A 55-year-old reinforced concrete water pipe, approximately 11,640 linear feet in length and 60-inch in diameter, transfers water treatment residuals from the East Side Water Treatment Plant to three off-site lagoons on the east side of Dallas, TX. Subsequent to the construction of the 60-inch residuals transfer main, five primary lagoons were built on-site at the water treatment plant, thus relegating operation of this main to overflow and wash water transfer to the off-site lagoons. Improvements of the three off-site lagoons has allowed the plant to transfer wash water to the East Fork of the Trinity River. The existing 60-inch residuals transfer main contains seven in-line manholes ranging from 1,200 to 2,000 feet apart, which many of the manholes are inaccessible. A comprehensive study on hydraulic capacity and condition of pipe, by CCTV inspection method, was performed to determine if the pipe can be converted to the new operating conditions of the water treatment plant. The biggest challenge during pipe inspection was limited access to the manholes due to unknown manhole locations, thus only 50% percent of pipeline was inspected. According to ASTM F 1216, the pipe is classified as “partially deteriorated condition.” After assessing the condition of the 60-inch residuals transfer main, four renewal and rehabilitation alternatives were proposed. These alternatives include: (1) replace main in the existing alignment by open-cut, (2) open-cut in new alignment, (3) trenchless rehabilitation by cured-in-place method, and (4) trenchless rehabilitation by sliplining. The objective of this study is to investigate advantage and disadvantage of each proposed alternative and perform cost analysis to find the most reliable and cost-effective method.

Circulating cooling water piping systems are critical to nuclear power station operations and overall safety. As nuclear power stations in the United States and around the world age and the piping systems reach their service life, utilities have initiated pipe replacement activities to comply with their NRC (nuclear regulatory commission) license commitments for safe operations and to ensure system performance doesn’t impact operations. Power plants need to consider their options on how to comply with life extension requirements of degraded pipe include dig and replace the piping systems as well as trenchless rehabilitation methods. The trenchless repair options include the design and installation of cured in place pipe (CIPP) and carbon fiber reinforced polymers (CFRP). Replacing a system often presents operational or construction challenges to nuclear power stations. In the case of a pipe rehabilitation project in a nuclear power station in the United States which this paper will review in details, the site’s design team was presented with the challenge of replacing a concrete encased cast iron piping system beneath the turbine building. Replacing the piping system was not operationally feasible and therefore, the repair method chosen for the pressure barrier replacement of the buried piping systems was a combination of CIPP and CFRP. This paper describes the successful design, planning, and implementation of a full structural rehabilitation of a cooling water piping system at the nuclear power station.

Pipeline inspection management, maintenance management, and asset management tools come in multiple flavors, and with them, multiple data formats containing asset-related information. Not all these tools can be easily integrated with each other or with geographical information systems (GIS), which is essential for asset mapping. Without GIS integration, data visualization and analysis to prioritize asset conditions and to develop a rehabilitation plan is extremely challenging, especially when the information is contained across different networks. The focus of this paper is to describe how the system condition risk enhanced assessment model (SCREAM)—an advanced condition assessment tool—and feature manipulation engine (FME) tools were integrated with GIS to assist the city of Baton Rouge/Parish of East Baton Rouge (C-P) with their SSO program to help manage field inspections. The goal being to help close the “Inspection to Work Order Cycle” and get repairs addressed quicker, allowing engineers to focus on the engineering side of things instead of spending time sorting through data. Additionally, this paper will show how to leverage ESRI’s platform to visualize condition assessment information though GIS using web-based data dashboards. A tool was developed to automate data quality assurance using FME to audit the sanitary sewer evaluation survey (SSES) and to provide a detailed list of SSES Pipeline assessment certification program (PACP) errors. This list of errors helps contractors identify issues that need to be fixed so that their submittals can be accepted as delivered, rather than going through iterations that can take anywhere from a few days to 2 months. These accepted submittals are then loaded into SCREAM for analysis and reporting. C-P used SCREAM, their asset management tool, to score, prioritize, and make recommendations based on Baton Rouge’s CCTV data. SCREAM’s first module, scoring, calculated inspection scores (maintenance, structural, I/I, and total). SCREAM’s second module, next step, incorporated the asset inventory, inspection logs, risk scores, work order history, and several logic tables to determine the appropriate next maintenance and structural actions for the assets. Then, SCREAM costing calculated the costs of repairs, replacement, rehab, and continued maintenance over time and chose the optimal methodology for addressing the utilities’ priority assets. The last step was to integrate the results with GIS. FME spanned networks and imported SCREAM results into the GIS environment. FME provided a flexible environment to configure and deploy monthly email notifications that a utility’s management team can use to track data quality and to generate pipe inspection work orders. Armed with information that was quality controlled by FME and processed by SCREAM scoring, next step, and costing, Baton Rouge can create re-inspection, maintenance, and rehabilitation plans.

In 2011, the Metropolitan Government of Nashville and Davidson County through the Metro Water Services (MWS) Department began an ambitious program to fulfill Clean Water Act requirements by planning, designing, and constructing wastewater system improvements. This program, known as the Clean Water Nashville Program, continues MWS’s commitment of renewing wastewater system infrastructure and reducing sanitary and combined sewer overflows to the environment. As of August 2018, Nashville completed the construction of 28 projects, totaling over $125 million in construction costs. Case histories of representative projects, including sewer rehabilitation projects, pipe conveyance improvements, and equalization/storage facilities, are discussed herein.

The city of St. Peters and the city of St. Charles, Missouri, created a joint venture (JV) to purchase finished drinking water from the city of St. Louis to supplement the water supply for the two communities on the north side of the Missouri River. The JV water pipeline is a critical component that provides these communities with water to meet their demands. The pipeline is a 36-inch ductile iron pipe (DIP) with a 2,000 foot 30-inch steel pipe that crosses under the Missouri River. The pipeline was installed in 1986 and is approximately 5 miles long. The pipeline has only had two leaks since it was constructed. Those leaks emphasized the critical nature of the pipeline and the consequences that a major failure would have, especially if the failure occurred under the river. The project included an evaluation of available inspection technologies capable of identifying and measuring pipe wall loss and detecting leaks. Indirect inspection methods were also con-sidered to evaluate the corrosion potential of the soil. This paper will review the process used to evaluate these technologies and explain why each was selected. The direct methods included electromagnetic (EM) technology to evaluate the integrity of the pipe wall, acoustics to identify leaks, and an external corrosion direct assessment (ECDA). The indirect methods included the use of Geonics and soil sampling to measure soil corrosion poten-tial. In addition to the condition assessment of the pipeline, the project included evaluating the flowmeter accuracy to determine if other unaccounted water loss issues existed in the system. The results of this project provided the pipeline owner with a comprehensive evaluation of the pipeline condition. The effort identified seven leaks and two wall loss defects, potentially indicative of pipe wall corrosion under the river. The leak detection helped resolve water loss concerns, which could not be accounted for in previous flowmeter data. The inspection was conducted using best-in-industry technologies to gather the data required to evaluate the pipe and the data to determine if repair, rehabilitation, or a secondary pipeline crossing under the river was needed.

When a pipe or water retaining structure is leaking, it is critical to stop the leak as soon as possible. However, there are times when taking the pipeline or structure out of service in order to perform the repair is not feasible. The Metropolitan Water District of Southern California (MWD) has successfully repaired active leaks on large diameter concrete pipes and water retaining concrete structures without shutting down these pipelines or structures by externally injecting of polyurethane, acrylate, or epoxy resins into these leaking pipelines or structures. This paper describes this repair method in detail. It discusses the conditions that make the repair viable, materials used for the repair, equipment used to perform the injection, and the construction methodology. The ultimate success of this repair method relies on how the repair is executed. Detailed repair procedures and important factors that affect the effectiveness of the repair are also described. Additionally, this paper discusses the advantages, limitations, and performance of the repairs. Finally, an application example of this repair method is provided.

The Louisville Water Company (LWC) provides drinking water to almost one million customers in the Louisville Metro area and surrounding counties through a series of 4,200 miles of water mains. LWC has implemented an ongoing condition assessment program that includes the inspection, analysis, and repair of large diameter transmission mains and pipelines on treatment plant sites. Pipelines within the scope are a variety of materials including prestressed concrete cylinder pipe (PCCP), reinforced concrete cylinder pipe (RCCP), cast iron pipe (CIP), and steel pipe. The technologies used for pipe inspection varied for each material and consisted of electromagnetic, leak detection, acoustic wave-based stiffness testing, broadband electromagnetic inspection, low-frequency pulsed eddy current inspection, and closed-circuit television. A total of more than 96 miles of pipeline have been inspected between May 2009 and August 2018. Failure risk analysis of the pipelines narrowed the massive scope to particular areas for further inspection and specific pipes in need of repair. This paper reviews the types of inspection data obtained from each inspection technology, how the inspection data was used to evaluate the risk of failure for pipes of various materials, and how high-risk pipes were repaired. This paper will focus on the condition assessment program work performed in 2017 and 2018.

The city of Portland gets its water primarily through three (3) large diameter lock-bar steel transmission pipelines, colloquially referred to as “The Conduits.” These pipelines transport water from the Portland Water Bureau’s (PWB) Headworks facility in the Bull Run watershed approximately 25-miles to in-town reservoirs through a mix of forested terrain and urban areas. In March of 2017, PWB began an inspection and condition assessment project with Pure Technologies on these pipelines in order to gain a better understanding of their existing condition. The team is using the latest internal pipe visual inspection methods, applying non-destructive pipe wall thickness examination technologies, conducting structural and remaining service life analyses, and developing maintenance, rehabilitation, and replacement strategies. Analyses on the collected data and results from the assessment will be presented, as well as the risk-based logic behind which parts of the conduits were chosen to inspect with which tools and methods.

Utility managers and other authorities have challenges when addressing appropriate intervals for inspection of gravity sanitary sewer pipelines. Frequent inspection of sewer network is not cost-effective due to large inventory of pipes and high cost of closed-circuit television (CCTV) surveys. Therefore, it would be more beneficial to first predict critical sewers most likely to fail and then perform inspection to maximize rehabilitation or renewal projects. Development of sewer condition prediction models is extremely vital for utilities to evaluate the short-term and long-term behavior of their pipe network considering different uncertainties. However, providing a prediction model is difficult due to lack of adequate data. This research uses a logistic regression model to predict the condition of sanitary sewer pipes based on data provided by inspection reports from city of Tampa. Three main factors, physical, operational, and environmental were considered during the selection of variables in development of this model. Independent variables, such as pipe age, material, diameter, depth, length, slope, watertable, and soil type were used to run the model. The logistic model predicted the condition rating of sanitary sewer pipes with 81% accuracy. The developed model can be used by utility companies and municipalities to forecast condition of sanitary sewer pipes, schedule inspection times, and make cost-effective decisions to match budget allocations.

The Washington, DC, sewer system is managed by DC Water. As part of its capital improvement program, DC Water is performing rehabilitation on their New Jersey B Street (NJB Street) trunk line sewer. This project is 4,434 linear feet of a 12-to-18-foot-wide arched CSO masonry sewer tunnel composed of brick and unreinforced concrete. The spring line to spring line crown of the pipe is being lined with geopolymer spray on mortar. No bypass is utilized, so all construction is during active dry weather flow conditions. The cross section of the pipe contains a large deep cunette which concentrates the dry weather flow at the invert of the pipe. A portable work platform/scaffolding system is utilized to spray the crown above the dry weather flow. This project traverses through the heart of the tourist district and runs under the National Mall. Construction started fall 2018 and will be completed by September 2019. Construction takes place at off peak rush hours from 7:30 pm to 5:30 am. This minimizes traffic and tourist disturbance and flow is typically lower during the night. The general contractor (GC) is utilizing a geopolymer mortar to provide a corrosion resistant composite structural enhancement to the tunnel crown. This paper focuses on the initial condition site assessment, finite element analysis (FEA) design of a geopolymer liner solution, construction challenges, and lessons learned.

Utilities face significant challenges as they age. Because wastewater collection systems are buried, these systems are “out-of-sight, out-of-mind”—until they fail. The need to allocate resources for condition assessment and cost-effective rehabilitation/repair of critical infrastructure before they fail continues to be a high priority for utilities across the country, and one of their most vexing challenges. More and more, utilities are turning to pipeline renewal and replacement (R&R) models to understand potential needs and to develop prioritized projects. While R&R models are not a new concept, the tools and services available have greatly improved in recent years. Through better understanding of these models and how they are applied differently, utilities can develop plans that are tailored to their needs and challenges. This paper will present three case studies illustrating how different utilities used modeling to develop collection system R&R projects for their respective CIPs using the same tool and similar data.

The use of lining water mains with cured-in-place pipe (CIPP) is growing in the marketplace. As the familiarity with the process increases, so does the need for a leak-tight reinstatement system. This paper will focus on advancements to the method of internal service reinstatement using a mechanical seal that is inserted into the service after lining. It is the evolution of a system where a hollow stainless-steel bolt was threaded into the opened service after lining. The concept was revisited with the cooperation of a robotics firm, resulting in a more effective mechanical insert and more effective tooling required to robotically install the insert. The system has undergone significant testing with respect to the ability to withstand vacuum, as well as the expected pressures in a water distribution system. Improvements include not only a more cost-effective and less time-consuming method, but also the ability to reinstate saddled connections from within the lined pipe and eliminate the reliance of bond or adhesion between the host pipe and liner.

Before 2014, the city of Edina identified portions of the water distribution pipe network for replacement based on network age and repair history. Based on observed evidence, a significant portion of replaced pipes remained in good condition. However, Edina proactively searched for solutions that would lead to a more targeted pipe replacement program and support coordination with other infrastructure investments like road reconstruction. In 2015, Edina implemented a pipe replacement program to maintain levels of service and upgrade the network in a gradual manner with minimal impact to residents in a given year. The city developed a protocol based on acoustic measurement technology to translate remaining pipe wall thickness measurements into pipe replacement plans. Edina’s experience is presented as a case study including the return on investments in pipe condition assessment, the proportion of allocated pipe replacement funds that could be redirected, how the city integrated condition data into its condition assessment process, lessons learned, and next steps.

America’s alarming infrastructure gap has been well documented and publicized. The Washington Suburban Sanitary Commission (WSSC) is among the largest water and wastewater utilities in the U.S. and is of course not immune to the issue. WSSC serves over 1.8 million residents of Montgomery and Prince George’s County through over 5,700 miles of potable water pipes. The backbone of the water system is 145 miles of large diameter (36-inch and greater) prestressed concrete cylinder pipe (PCCP). WSSC top priorities are to provide safe and reliable water to their customers, protect public safety, and conducting a sustainable PCCP Inspection and Condition Assessment Program. The high economic and social costs of a full-scale, large-diameter pipe replacement program has led WSSC to embrace a condition assessment as part of their asset management program. WSSC’s PCCP management program was started nearly 10 years ago and is widely recognized as the industry leader. Since its inception, the program has evolved from a conventional condition assessment and engineering approach to an integrated, near-real-time pipeline monitoring, and management system. This system has been built upon an online GIS based management system of the large inspection data sets (including live monitoring data) and engineering analysis allowing WSSC to manage their transmission mains in a dynamic manner. WSSC’s data management system goes deeper than the conventional node-to-node (valves, appurtenances, etc.) resolution and drives down to an individual pipe-by-pipe basis, allowing for detailed and direct analysis of each individual pipe in a pipeline. Automated alerts and up-to-date reporting have been incorporated into the online GIS based management system providing WSSC almost instantaneous access to all its pipeline information. This paper will discuss the program’s technical evolution and current approach, as well as the operational and management challenges of executing such an extensive system condition assessment program. Nearly every department within WSSC is essential to the program’s effectiveness. The collaboration between such a diverse group of stakeholders, with a corresponding range of competing projects and focuses, is a primary challenge of the program, but also a primary ingredient for the program’s success. Other key ingredients include a dedication to innovation (and the associated critical analysis that comes with new approaches), establishing strong processes but remaining opportunistic, and valuing a “boots-on-the-ground” assessment of their assets. The paper will also share lessons learned by WSSC’s engineers in managing its condition assessment program. WSSC will also discuss their visions to maintain their position as industry leaders for another 10 years!

Carbon fiber reinforced polymer (CFRP) has been widely used for the repair of damaged prestressed concrete cylinder pipe (PCCP) in the last ten years. There is some uncertainty regarding the long-term performance of CFRP repair under internal and external loading conditions. This study provides experimental and computational data regarding the performance of CFRP repair for the damaged 54-inch PCCP under external loading. The CFRP repair was installed in 2012 and the pipe was tested under a 328D excavator which moves on two tracks and exert 320 psi downward force in 2016. External experimental live load data was gathered as the as a result of the 328D excavator pass over the pipe for approximately 2.5 hours at a sample rate of 10 Hz. Strain gauges were installed on the inside surface of the CFRP repair site at the middle of the pipe and close to the joint. Hoop and longitudinal strains were measured at four locations on each cross section (12, 3, 6, and 9 o’clock positions) during a series of load events. The main objective of this study is to provide computational and experimental data, particularly for the level of strain created in both longitudinal and circumferential directions under live load events using 328D excavator load. This study provide a better understanding of short term behavior of CFRP repair using computational and experimental data which could be used for adjusting the margin of safety for the design.

Life cycle cost analysis (LCC) is a tool allowing utility owners to make sound project decisions, considering both capital and operating costs over a long-term analysis period. Capital projects prioritized by rigorous LCC analyses facilitate strongly supportable business case decisions. More often performed for projects such as treatment plants or pumping stations, rarely is LCC used to make decisions on collection system rehabilitation. This is unfortunate because rehabilitation projects are consuming a greater percentage of utilities’ capital budgets. This paper presents a detailed description of the LCC methodology as it pertains to collection system rehabilitation decisions. A simple spreadsheet-based case study is presented for collection system rehabilitation of lateral liners using cured in place plastic (CIPP) lining. During the presentation many often overlooked variables influencing life cycle rehabilitation costs will be identified and methods to incorporate them into the LCC will be described. These include not only initial capital and long-term operating costs, but also a broad range of other evidence including job site tests, published reports, manufacturer product data, as well as historical local experience. The broader the range of evidence incorporated into the analysis, the more accurate is the LCC and corresponding business case.

Pipe penetrating radar (PPR) is the application of high-frequency electromagnetic waves to measure the condition of non-ferrous pipes. High resolution antennae allow for early detection of voids developing outside the pipe wall, before they grow to a problematic size or become sinkholes. PPR surveys are conducted from within the pipe. The antennae are normally carried by a remotely-operated crawler. This paper will look at recent advancements in PPR technology through a recent case study, and demonstrate how quantitative data can aid asset owners in making critical decisions about their pipes. The case study demonstrates how PPR was used to assess the condition of a critical sewer main in Surrey, British Columbia, Canada. Data from the PPR survey gave the owners confidence in their decision making, and provided the basis for cost-effective rehabilitation planning.

For nearly a decade, the city of Fort Worth has been systematically evaluating their sanitary sewer interceptors as part of the Interceptor Condition Assessment Program or ICAP. The data collection for the program has consisted of the deployment of a floating platform which includes a high-resolution video camera, a light detection and ranging (LIDAR) head to evaluate the pipe wall above the water surface, and a sonar head to evaluate pipe wall and lodged debris below the water surface. The data is compared to standard inner diameters for their respective pipe classes to determine the extent of pipe corrosion. Pipe segments (from manhole to manhole) are ranked best to worst on a scale of 1–5. Given the large amount of data to process for a collection system spanning the 350-square-mile city, condition ratings were assigned based on the worst corrosion found anywhere along a segment, requiring further analysis to determine the extent of necessary rehabilitation work. Kimley-Horn was tasked with interpreting the city’s findings for over 10,000 linear feet of three sanitary sewer interceptors ranging in size from 24-inches to 54-inches throughout its Clear Fork Basin. Most of the lines in this basin are more than 50-year-old reinforced concrete pipe. Additionally, access to these interceptors for maintenance is very difficult given their locations traversing the Union Pacific Davidson Railyard, a commercial district, a major arterial road, multiple highways, and the city’s premiere park. This paper will discuss how the risk assessment data was evaluated to pinpoint portions of the pipelines with the greatest failure risk, reducing necessary rehabilitation to less than 5,000 linear feet of pipe and saving the city approximately $3,000,000 dollars. The paper will also explore design challenges related to the installation of cured-in-place pipe (CIPP) in very difficult locations. Construction is anticipated to begin in the spring of 2019.

After hundreds of area homes suffered major sanitary sewer backups following a severe storm in 2010, the Chicago suburb of Elmhurst launched the $10 million Southwest Elmhurst Wet Weather Control Facility project. This comprised a major upgrade to an existing lift station, over 5,000 feet (1,524 m) of 18” (450 mm) force main, and a two million-gallon (7.6 ML) storage tank. While all aspects of the project presented difficulties, the installation of the force main, with three crossings of a certified levee, a river traverse, and over 700 feet (213 m) of blind drill through a wetland, was particularly challenging. At the time of the design the desired pipe, restrained-joint PVC, was not available. Working with the manufacturer over a period of 18 months, this pipe was finally produced two weeks before construction began. This paper will discuss the various construction challenges of the project, including a virtually inaccessible installation adjacent to the river. The project was successfully completed and has been in operation during subsequent major storm events with only a handful of back-ups experienced.

This paper presents the approach, methods, and challenges for undertaking repairs to York Region’s sanitary sewers. The Regional Municipality of York (York Region) carried out detailed closed-circuit television (CCTV) inspections on the York-Durham Sewage System (YDSS) to assess the rate of inflow and infiltration and to identify sewer sections in need of immediate repair. Based on the inspections, deficiencies were identified at two (2) maintenance holes and fourteen (14) sewer sections that include minor cracks, infiltration, encrustation, and roots and debris in the system. The diameter of the sewers ranged from 20 to 54 inches (525 to 1,350 mm), with a total distance of 1.2 miles (1.8 km). The rehabilitation consisted of spray applied liners for the maintenance holes and installation of localized chemical grout to the sewer sections. These locations were distributed across York Region in three separate cities, with the location of the proposed rehabilitation work occurred within flood plains, high traffic, and environmentally sensitive areas. York Region, Hatch, and associated contractors collectively worked together to mitigate and resolve project challenges and completed the rehabilitation of the YDSS within the prescribed construction timeline.

The summer of 2018, the Narraganset Bay Commission (NBC) undertook their first large scale geopolymer mortar pipe rehab project as part of the Route 6 and 10 Interchange reconstruction in Providence, RI. This is part of a Rhode Island Department of Transportation (RI DOT) project to fully reconstruct the Route 6 and 10 approach ramps and elevated superstructure by 2020. The trenchless subcontractor rehabilitated 2,430 linear feet (LF) of brick pipe up to 60” diameter round and including vertical ellipses ranging 30”×45” to 38”×57”. This was done using spin cast geopolymer lining (SCGL) utilizing GeoSpray geopolymer mortar. SCGL provides a structurally independent, corrosion resistant new pipe in a pipe. Because many of the manholes were located in the middle of a 4-lane highway, maintenance and protection of traffic (MPT) played a critical part in the success of this project. Fortunately, SCGL requires a very small construction footprint, beneficial in dense traffic areas, and it does not require excavated insertion pits. The contractor completed all the rehabilitation in August 2018. This presentation will focus on the trenchless options considered, why NBC selected geopolymer mortar, construction challenges in the middle of a highway, and lessons learned.

The Ashley Interceptor Rehabilitation—Phase 8 differed from previous phases of the Sewer District’s interceptor rehabilitation program because in addition to the sections of the interceptor that was laid in the marshes associated with the Ashley River, other portions were constructed within narrow, live oak lined roads in an upscale neighborhood. The setting(s) proved to provide interesting challenges including public relations management, difficult access issues, and protection of private properties as well as environmental resources. This case study of the Phase 8 cured-in-place pipe (CIPP) rehabilitation of 4,650 linear feet (LF) of reinforced concrete pipe (RCP) highlights the unique challenges presented to an experienced team comprised of the NCSD, the consultant engineer, and the contractor. The project was bid in May of 2018, with eight qualified contractors and bids ranging from $1.83 to $3.97 million. The contract was awarded to SAK Construction, LLC, as the lowest qualified bidder. Prior to the commencement of construction, The NCSD, the engineer, and the contractor presented the project scope to the neighborhood to elicit acceptance. Their understanding of the necessity of the project allowed their patience with the disruptions. Construction began in August, with completion scheduled for January 2019. In addition to the interceptor rehab, fourteen manholes and the force main receiving junction box (JB) at the downstream end of the project were rehabilitated. Several service and main laterals were reinstated in the interceptor after the new pipe was cured.

This paper provides information regarding Tucson Water’s proactive asset management program for PCCP, which includes continuous acoustic monitoring, cathodic protection, and implementing immediate replacement or repairs. A specific case involving inspection and repair of a distressed 54 in. PCCP is presented to demonstrate how verification inspection can provide information that affects how the pipeline is managed and cathodically protected.

This paper explores the unique performance parameters of a pressure sewer rehabilitation (including significant vacuum conditions), the currently available rehabilitation alternatives and their limitations, and industry claims versus installation history. Pipeline rehabilitation is a common industry practice for gravity systems and small diameter pressure applications. What makes this project unique is the size, design pressures parameters, and internal diameter constraints for a critical asset, leading to the need for a rehabilitation alternative with a proven track record. King County’s Interbay force main sewer system was constructed in 1966–67 and consists of dual 36-inch steel pipes and dual 48-inch reinforced concrete pipes (RCP) between the Interbay Pump Station and the force main discharge structure. The overall rated capacity of the station is 133 million gallons per day (mgd) with both force mains on-line, but limited to 130 mgd using station controls. With only one force main online, the maximum flow is 78 mgd. Inspections of the 48-inch RCP mains indicate that the RCP has a remaining service life of 10–20 years, leading to the need for rehabilitation to extend the design life by 50 years. Rehabilitation alternatives were evaluated on a range of technical performance requirements, focusing on the hydraulic capacity and maximum and minimum pressures. Selection of cured-in-place-pipe (CIPP) lining alternatives were further compared against available resin alternatives (such as “green”, vinyl ester, and epoxy resins). The finding was that only structural CIPP hot water cure with epoxy resin has the proven installation track record for this specific size and operating condition.

The city of Virginia Beach made a proactive decision to evaluate the condition of existing subsurface utilities in coordination with an upcoming roadway improvements project along a well-travelled corridor within Virginia Beach. Approximately 5,111 linear feet of 20-inch cast iron water main was inspected using pipeline condition assessment (p-CAT). The collected condition assessment data was utilized to develop a risk profile for the entire length of the tested pipeline based on a comparison between the original and remaining wall thicknesses. This data ultimately allowed for DPU staff to prioritize various sections of the water main within the anticipated envelope of roadway improvements. The higher priority subsections were located outside of these limits eliminating the need for rehabilitation prior to the planned roadway construction. The opportunistic condition assessment performed allowed for the city to gain a robust understanding of specific logistics and/or lessons learned for deploying p-CAT and/or similar technologies.

The Pardee Tunnel is a 2-mile long concrete-lined tunnel with an 8-foot diameter horseshoe cross-section. It was constructed between 1926 and 1929. The tunnel excavation was initially supported by timber sets and timber lagging. The Pardee Tunnel is critical to East Bay Municipal Utility District (EBMUD) raw water system. It provides 90 percent of EBMUD’s water supply. The last manned inspection occurred in 1962. A manned inspected was attempted in 1982 but was aborted due to excessive ground water intrusion. However, without a redundant conveyance tunnel, dewatering the tunnel for a manned inspection is difficult due to operational constraints. In order to reduce outage costs and water supply concerns, a remotely operated vehicle (ROV) was launched through the reservoir outlet tower to inspect the tunnel during the winter of 2018 rather than a manned inspection. Prior to launching the ROV, a team of 10 divers removed three tons of unforeseen debris blocking both access points into the tunnel. The ROV was equipped with 3D multi-beam sonar, inertial navigation system, 2D multi-beam imaging sonar, tell-tails, a hydro-phone, and a dye injection system. Flows were reduced to approximately one foot per second during the inspection. A comprehensive decontamination plan was developed to ensure invasive species were not introduced during the inspection. The data collected formed the basis for the condition assessment which concluded that the structural integrity of the tunnel and liner is good with no significant defects. The condition assessment report recommended continuing seepage monitoring and regular inspection by manned entry or ROV. Conceptual design drawings were developed to improve future tunnel access and facilitate planned or emergency repairs.

The city of Pacifica, California, (city) is implementing a multi-year capital improvement program to eliminate capacity related sanitary sewer overflows (SSOs) by January 1, 2019, to comply with the San Francisco Regional Water Quality Control Board's (RWQCB’s) cease and desist order (CDO). The Pedro Point Neighborhood Sewer Rehabilitation Project is a key component of the capital improvement program (CIP) that included replacement of over 16,000 linear feet of 6-in, 8-in, and 10-in diameter vitrified clay pipe (VCP) with 8-in and 12-in diameter high density polyethylene (HDPE) pipe using pipe bursting. Several project challenges included: approximately 50% of the sewer mains are located within backyard easements; open trench in the narrow neighborhood roadways would require street closures impacting access to over 250 homes; the neighborhood elevation varies over 300 feet within the project limits and the steep roadway slopes makes open trench construction while maintaining public safety challenging; and the sanitary sewer mains cross both natural gas and potable water mains that would require careful excavation, potentially even hand excavation, potentially reducing the open trench production rates, and thereby extending the project schedule. Pipe bursting was chosen as the preferred construction method based on the city's previous positive experience, reducing roadway surface impacts, reducing potential impact to adjacent utilities, and higher anticipated pipe replacement production rate. The project was successful because of the following key activities: city maintenance staff interviews were performed during the design phase to document easement access requirements; implemented a detailed existing utility research and potholing effort to confirm location and depth of existing utilities; existing sewer main condition evaluated using closed circuit television (CCTV) to identify spot repairs; implemented a comprehensive public outreach to present long-term benefit to community; required all contractors to be prequalified; mandatory project bid walk through all backyard easements; and regular construction progress updates.

While pipe ovalization is a common occurrence during the manufacturing of pipe sections, ovalization can also occur in pipelines during and after installation and construction. To determine the acceptability of newly constructed sections of pipeline, inline inspection (ILI) tools, or pigs, are often run to measure ovality. However, the ILI tool often flags numerous locations that do not satisfy the maximum allowable ovality criteria of 5% required by CSA Z662 (3%–6% if limit states design was used). This is possibly due to external forces (e.g., soil cover) and the low internal pipeline pressure used to run the ILI tool. It is postulated that these non-satisfactory ovality readings would not be present at higher internal pressures (i.e., operating pressures). The major objective of this study is to better understand the relationship between internal pipeline pressure and other variables with the ovality measurement. Based on results from elastic finite element analyses (FEA) of different pipe sections and loading conditions, equations are proposed to estimate pipeline ovality based on depth of cover, pipe geometric and material properties, and internal pressure (represented by a “deflection parameter”, α). A quadratic equation, as well as a simplified linear equation, were developed in this study. These equations, based on 68 different FEA load cases, can be used as a screening tool to estimate the ovality of a pipe section. Whichever equation (i.e., linear or quadratic) is used to predict the ovality in a pipe section, the deflection parameter, α, provides a means of summarizing overall trends. For example, if the pipe stiffness is increased, α (and thus ovality) decreases. Conversely, if overburden pressure is increased, α increases. Finally, if the internal pressure stiffening is increased, α decreases. The last observation is the most critical for this study as internal pressure is the most practical mitigation for reducing the number of ovalities flagged by an ILI tool post-construction. Increasing internal pressure has the additional benefit of improving the quality of the measurement data by reducing/eliminating “surging” of the ILI tool (i.e., erratic velocity changes due to sticking and slipping of the tool).

The city of Winnipeg, MB, Canada, has a large and old combined sewer network that was constructed using a wide range of materials, cross sections, and construction methods. As with many jurisdictions in North America, their rehabilitation needs have become considerably more challenging over time. This paper focusses on the design considerations to rehabilitate two sites with egg shaped monolithic concrete combined sewers with numerous major defects in the form of sewer fabric decay (i.e. general surficial material degradation), localized invert loss, infiltration, and longitudinal four point fractures. The sections included pipes that were 1,800 mm high×1,350 mm wide (72”×54”) and 2,700 mm high×1800 mm wide (108”×72”) and conveyed dry weather flows ranging from 1.9 to 162.8 L/s (30 to 2,580 USGPM), respectively. The combination of defects present with active infiltration meant that active deterioration processes were present in form ground loss around the sewers. The sites themselves posed considerable access challenges, as one was located on a former road right of way now leased to a private recycling company and located adjacent to active Canadian Pacific Railway (CPR) tracks. Proximity to active rail tracks necessitated seeking approval from CPR on a detailed sequential phasing plan for the shaft construction. Since the requirements for the shafts were dictated by both the rehabilitation method and the contractor’s means of shoring construction, final approval for shaft construction at the site could not take place until after contractor procurement. Design and procurement included five unique rehabilitation alternative systems: reinforced cured in place pipe (CIPP), grouted in place glass reinforced polymer (GRP) liners, bonded in place fibre reinforced polymer (FRP) liners, centrifugally cast concrete pipe (CCCP), and grouted-in-place spiral wound PVC strip liners. Each technology was assessed and specified based on their unique installation and long term performance characteristics. While all of the deteriorated pipes appeared stable and were not at risk of short term failure; some of the pipes displayed evidence of accelerating deterioration which required a rehabilitation system designed for full pipe-soil loading models as well as hydrostatic groundwater loads. Design methodologies and minimum quality assurance (QA) requirements were dictated by the tender documents for each rehabilitation technology to promote an “equal” assessment of alternative technologies in a competitive environment. The rehabilitation contract was awarded based on the use of reinforced CIPP technology in late 2017 and installation of the liners was completed in November 2018.

The city of Houston is facing a challenge with an existing 30, and 36-inch cast iron water line concentrated in the vicinity of the city’s Museum District and the Galleria Mall retail and business area, and surrounded by majestic live oak trees. The lines were constructed in the 1940s and consist of cast grey iron material with lead caulked joints. The leak history of these lines makes them a maintenance burden for the city, and causing disruption to businesses and residents in the area. However, coupons cut from the existing line indicate the existing pipeline is structurally sound and free of corrosion—the problem was at the joints. This paper will review the issues involved in the trenchless rehabilitation method with the least possible surface disruption.

The joint transmission main (JTM) is part of the 38 mile long Joint Regional Water Supply System, operated and maintained by the South Coast Water District in California. The pipeline, made of 60 in. diameter PCCP manufactured in early 1960s, transports potable water to several service areas with limited redundancy. In 2010, the District started a condition assessment and repair program by performing an electromagnetic (EM) inspection of a 3 mile long section, of which a 1.5 mile long section was re-inspected in 2016. The EM inspections identified seven distressed pipes, one underneath a major highway (SR 133) with 19 ft of soil cover, one underneath the shoulder of the highway, two in the vicinity of the highway adjacent to a major new development, and three others in difficult to access wooded areas. The distressed pipes have a design working pressure of 150 psi to 200 psi and operate at pressures close to design. Considering high consequence of failure, the distressed pipe under the highway was repaired proactively using carbon fiber reinforced polymer (CFRP) liner in Phase 1 of the project. Phase 2 was performed on two pipes to verify the EM results by external inspection, reevaluate failure risk, and perform external post-tensioning repairs if necessary in the same shutdown. External inspections indicated that the EM inspection had significantly overestimated the number of wire breaks, and repair of the two investigated pipes was not necessary at this time. While the district and its consultants spent significant effort in planning and execution of Phase 2, the results proved such efforts worthwhile by avoiding unnecessary repairs and providing valuable information for planning of future inspections and repairs of the JTM. This paper presents planning and execution of both phases of the project from both the district’s and the consultant’s perspectives.

A majority of water mains in North America are made of cast iron (CI). The use of CI pipes in water utility started at the end of the nineteenth century and many of the pipes are still functioning even after their expected lifespan. CI pipelines are susceptible to external and internal corrosion over time, which can significantly affect their mechanical strength and hydraulic performance, and consequently the water distribution system (WDS) reliability. Buried CI water mains have experienced the highest number of failures due to corrosion deterioration over time. Since most of the water pipelines are running underground, physical condition assessment of pipelines in a distributed network is often expensive and time-consuming. Existing research on WDS reliability based on statistical failure prediction methods typically assume a constant failure rate and ignore time-dependent strength change due to corrosion. This paper proposes a framework for modeling the time-dependent mechanical reliability of WDSs with CI pipes. Time-variant failure of pipelines is estimated using fragility analysis that accounts for the decrease in pipeline wall thickness due to the formation of corrosion pit on the pipeline wall. The impact of internal corrosion on hydraulic performance is evaluated using a time-variant roughness model. A hypothetical WDS is used to illustrate the proposed framework. The results of the case study show that pipe corrosion can significantly impact the reliability of a WDS as it ages. For instance, the mechanical reliability of the WDS in the case study dropped from 100% at the initial state to 16.5% at 60 years due to corrosion. The proposed framework links the deterioration of pipeline strength and hydraulic performance with system reliability and can, therefore, form the basis of a reliability-based planning for maintenance and rehabilitation.

Predicting the future performance of assets is an essential element in life cycle cost assessment (LCCA) by providing the economic remaining service life of pipelines. Performance prediction models which can provide long-term accurate remaining economic life analysis are crucial for tools for decision support for LCCA. Under Water Environmental and Reuse Foundation (WE&RF)’s strategic asset management (SAM) challenge, the remaining economic life analysis (RELAY) tool was developed. This platform provides utility managers with piloted and validated state dependent and time-dependent performance prediction models for accurate long-term remaining economical life analysis with the support of established data standards and performance indices. RELAY tool can develop deterioration curves to be used for strategic, tactical, and operational level LCCA decision support depending on the data availability. This paper presents how the remaining economic life analysis provided by the RELAY tool can be used in the long-term accurate LCCA. The demonstration includes how RELAY tool can be used to determine effective funding strategy using the principles of LCCA so that wastewater utilities can prioritize and budget for an ongoing asset management program that covers the upgrade, renewal/replacement of existing assets. The LCCA with the improved decision support with the RELAY tool is compared with the current practice of using design lives of assets with straight-line depreciation to showcase the benefits of using the new approach.

Stamford, Texas, a small town of approximately 3,000 residents located 150 miles west of Dallas, was experiencing frequent leaks in its sole water supply line. The city sourced water from manmade, city-owned Lake Stamford, positioned 10 miles northeast of city limits. The existing line, an 18-inch concrete steel cylinder pipeline, was installed in the early 1950s and was becoming increasingly problematic due to multiple and frequent leaks and high cost of repairs, necessitating installation of a new pipeline. The new line was installed adjacent to the existing pipeline, following the existing 15-mile transmission main from the raw water pump station on the southeast edge of Lake Stamford to the water treatment plant (WTP) in the city of Stamford. Due to the remote location of the proposed line, fusion-welded PVC pipe was selected to minimize the possibility of leaks in the new pipeline (no gasketed joints) and utilize a material that the city crews were familiar with repairing if that became necessary during the lifetime of the 79,600-foot 14-inch main. Decreasing pressure classes of pipe were used along the route to reduce the cost of the pipe used in the project. Further detail on the planning and challenges of installing a new line in a narrow easement alongside a leaking pipeline that was required to stay in service during construction will be discussed within this paper.

Over the years, many engineering, environmental, and related research organizations placed much study and analysis on drinking water pipelines, whereas metallic wastewater pressure pipelines such as force mains have received less attention yet are also subject to similar deterioration and unanticipated leaks. For many water utilities, the value of buried pipeline assets often exceeds the value of treatment facilities. As pressure pipelines continue to age and deteriorate, unanticipated breaks and resulting emergency repairs are creating an increasing percentage of utilities’ operating budgets. In addition, public inconvenience and repair costs, fines, or sanctions may be imposed for the release of untreated wastewater to the environment. To shift from a reactive to a proactive strategy, many utilities are embarking on programs to assess the condition of buried assets and implement rehabilitation projects to extend the life of the pressure pipelines. To address these challenges, a condition assessment strategy for pressure pipe should include: a progressive inspection process that utilizes broad diagnostic inspection tools among the inventory of pipelines; a risk assessment of each asset that incorporates the likelihood of failure and consequence of failure for each asset; and a qualitative, quantitative, and detailed description and assessment of the condition of each pipe. A tiered approach for deploying inspection equipment focuses on providing the most important data, in the most relevant locations. By focusing specific cost-effective technologies only on the assets where the data is most relevant, unnecessary inspection costs are avoided. This paper will focus on application of a tiered condition assessment approach in a South Florida, particularly in Fort Lauderdale, Florida. South Florida has unique challenges related to wastewater pressure pipe condition assessment, including: many miles of pressure pipe due to flat topography, resulting in higher costs for condition assessment; corrosion due to salt water intrusion; and wastewater pressures are lower than drinking water pressures, which result in fewer applicable condition assessment technologies.

There is a significant amount of AWWA C303 bar-wrapped pipe (BWP) and C200 steel pipe water transmission mains installed across the United States. While condition assessment of aging BWP lines has typically not received as much attention as some other pipe types (e.g., PCCP) due to its forgiving characteristics and predominant failure mode of significant corrosion followed by leakage as opposed to catastrophic burst, it is receiving increasing attention as awareness of degraded infrastructure increases and additional resources become available. In terms of effective asset management of long sections of pipelines installed since the 1940s, survey level inspection technologies allow owners to obtain information on the general condition of the pipeline at a reasonable cost and identify areas of the pipeline that require higher resolution and more costly inspections, rather than directly performing costly inspections along the entire pipeline alignment. This paper presents a condition assessment project performed on approximately 2 miles of 16 in. to 24 in. diameter BWP and 0.5 miles of 18 in. diameter cement mortar lined steel pipe installed between 1950s and 1980s using acoustic pipe stiffness testing technology. The project scope included external inspection at selected locations to determine pipe design properties for analysis, structural evaluation of the as-designed pipes with respect to the current AWWA standards, acoustic inspections, failure margin analysis, evaluation of soil corrosivity, and performing a combined evaluation of all data to identify areas of the pipelines with higher likelihood of distress and to develop a plan for future inspections and maintenance. The paper shares the findings of all phases of this project and discusses the effectiveness of the utilized condition assessment approach in assisting the city as part of their asset management program.

Have we reached the tipping point of technology gathering data in the field more quickly and accurately than human data acquisition for condition assessments for water and wastewater facilities? This paper will evaluate the state of the art technology in this area in comparison to the capability of human acquisition efforts. CCTV was one of the first entrants into the condition assessment arena followed by ultrasonic equipment, magnetic flux tools, and most recently drone technology. Field data acquisition for water and wastewater facilities has been developing since the 1970s. The major challenge with some of the data acquired by technology was the interpretation of the data. Some early CCTV data was very difficult to interpret. This paper will also look at various technologies and how interpretation of the data has improved over the last four decades. It will also look at human data acquisition and how it has evolved. Have we reached the tipping point where technology-based data acquisition overtakes human data acquisition or is there a balance between the two?

The Rose Canyon Trunk Sewer (RCTS) is a 60-inch diameter plastic-lined reinforced concrete pipe (PLRCP) with plastic weld strips installed at each joint. Following inspections, it was observed that the lining at the joints had failed. The RCTS runs throughout an open space, environmentally sensitive area rich with riparian habitat. Other alignment challenges included multiple railroad crossings and an adjacent freeway. Numerous trenchless rehabilitation options were evaluated to repair the failed plastic liner weld strips, including both joint repair and lining methods. The potential environmental, encroachment, and community impacts of the rehabilitation along with the overall cost and construction schedule were considered in the ultimate recommendation. Internal mechanical pipe seals were selected to repair the pipe joints via manned entry of the trunk sewer, as this method was the least invasive to the environment and the most cost effective. Details of the development of the RCTS rehabilitation design along with the lessons learned during the construction will be discussed.

This paper presents 1) results of nondestructive evaluation, ultrasonic testing, performed on prestressed concrete cylinder pipe (PCCP) components during a condition assessment and 2) validation of the nondestructive testing results in the laboratory on a sample with known defects. To manage the need for repairs, PCCP components are tested using a sonic/ultrasonic system that collects resonance frequency data and measures the propagation velocity of ultrasonic waves in concrete. For validation of the sonic/ultrasonic test results, a shear wave array system and was deployed pipes identified to have defects. The capability of the sonic/ultrasonic system was also validated in the laboratory on a reference concrete sample with known defects. Based on the results from this study, ultrasonic testing is capable to determine the location, approximate size of a delamination within the pipe core. The shear wave array also provides information related to depth of the delamination.

Most water systems across North America are struggling with managing the required renewal plans of their buried water assets that have reached the end of their service life. One of the primary concerns of water utility asset managers is prioritizing renewal of these buried assets to ensure that the right pipes get replaced first. The Regional Municipality of Peel found that by exclusively using their current desktop model they were replacing water mains in good condition. The region’s desktop model was missing a critical parameter: evidence-based condition information. The region engaged Echologics in a pilot study to gain condition assessment measurements on metallic water mains in Mississauga and Brampton. Wall thicknesses were measured on 133 segments (16 kilometers) of buried water mains with no interruption to service, costly excavations, or extensive support from utility crews and all at a cost of less than 1.4 percent of the cost of water main replacement. Three non-surfacing leaks were also pinpointed during the study. This paper discusses the results of the pilot and how condition assessment information was used to target spending on assets that only truly required replacement and deferred the cost of replacement on assets in good condition.

Under construction since 2011, the Hanlan Feedermain, a 2400 mm, 14 km feedermain located in Peel Region in Ontario, was placed into service February 2019. This paper describes the design and execution of the commissioning process using the first successful implementation of spray disinfection on a large scale feedermain in Ontario, since this method was first allowed for usage by the AWWA for large diameter mains in 2014, and the challenges and methodologies utilized to complete it.

The city of Rosenberg, Texas, and the Brazosport Water Authority (BWA) came together to define a $52 million contracting and capital cost sharing scenario to design and construct a 40-mile large diameter water transmission pipeline and pump station facility to transmit potable surface water to the city of Rosenberg. The primary purposes of this project were: (1) to stabilize the water rates for BWA member cities; (2) to enhance the partnership between city of Rosenberg and BWA to address future growth in the region; (3) to enable city of Rosenberg be in compliance with subsidence mandates through 2025. Schedule was a significant driver for this project due to the city of Rosenberg’s surface water conversion compliance deadline. In order to meet the required schedule, the project was divided into 6 separate construction packages that could all be under construct at the same time. During the construction, in August 2017, Hurricane Harvey deposited historic amounts of rainfall (over 50 inches in some locations) over a large portion of southeast Texas. Very large sections of Brazoria, Fort Bend, and Harris Counties were flooded for weeks, a condition that raised groundwater to near-record levels region-wide. In addition, there were delays in contractor’s receiving pipe deliveries due to a local PVC manufacturing facility being down due to Harvey impacts. The pipeline alignment traverses a section of Texas with a long history of oil and gas resource development. Both Brazoria and Fort Bend Counties are crisscrossed by active and abandoned petroleum pipelines. Undocumented pipelines were encountered in several locations, requiring prompt redesign of the pipe profile and reconfiguration of air valve locations. Rapid development in the greater Houston area, particularly in Fort Bend County, also presented construction challenges. Areas contaminated by a petroleum product spill at some time in the past have also been encountered within project limits. Construction of the project is complete, and the water transmission line and pump station are currently operating. This paper will discuss the challenges faced when constructing and starting up 40 miles of water transmission and the associated pump station within 18 months.

The Diablo Water District (district) is located in the northeastern part of Contra Costa County (county), in Northern California. One of the largest areas of anticipated growth for the District is on Bethel Island, a 5.6 square-mile island in the San Francisco Bay Delta area that is expected to grow from its current population of 2,200 residents to over 7,000 residents by 2040. In 2009, the County rebuilt the single, aging bridge that connects Bethel Island to the mainland with a new 900 ft long concrete bridge. As part of the planning for the bridge, the county allowed the district to reserve space within the bridge structure for construction of a future water pipeline with one restriction—no modifications would be allowed to the bridge during future water line installation. Growth within the district is driven and funded by development; because development was not active on the island in 2009, the district could not support the full predesign of a future water pipeline and could only give conservative guidance to the county in preparation for a future pipeline. In 2013, the district began working with a land developer to plan for a new 500-unit development on the island. The development was to be connected to the District’s main distribution system via a new 18-inch water pipeline over the Bethel Island Bridge. This paper discusses the design conditions considered for the pipeline: thermal expansion and contraction of the pipeline, differential seismic displacements between the pipeline and bridge, ground settlement at the bridge abutments, pipeline stability and flexibility, and overall constructability—all of which had to comply with the county’s requirement of “no bridge modifications”. The paper concludes with some lessons learned during construction.

With a net population increase of 100,000 plus over the last decade in Washington, DC, there has been major infrastructure developments and booming real estate construction, e.g., streetcars, two stadiums, three bridges over the Anacostia in addition to many residential buildings. Often these projects have foundations close to our buried infrastructure. The need for underground parking coupled with restricted building heights has resulted in foundations that are often deeper than and/or are very close to the buried water and sewer infrastructure. In certain instances, the foundations are proposed over or encompassing our sewer infrastructure. In the nation’s capital, modern urbanization started with the oldest trunk sewers and interceptors built from the 1860s through the 1930s with masonry made from a combination of brick, stone, and later non-reinforced plain concrete. These empirically designed and constructed infrastructure predate many modern engineering theories, i.e., soil mechanics post 1930s. DC Water engineers remain at the forefront of protecting these mission critical linear assets of indefinite life duty, by actively managing the forthcoming impacts via collaborating with stakeholders, and by: enforcing the best managed geo-structural practices in design and construction; protecting both the buried linear infrastructure and forthcoming new construction throughout the life cycle of both; and by facilitating future maintenance and expansion. This presentation will showcase a few highlighted projects in the past decade which have led DC Water to develop enhanced utility protection requirements for adjacent construction; and demonstrate that DC Water’s implemented best management practices have a win-win-win outcome for the environment, the developer, and the rate-payer.

Water utilities were traditionally required to deliver their projects using the design-bid-build (DBB) method. However, innovative and more efficient project delivery methods such as design-build (DB) are growing in use in this industry. The objective of this study is to benchmark DB project administration practices in the water industry, focusing on the U.S. Southwest/Pacific region. Structured interviews were conducted with four utilities that are experienced with successful DB delivery. One utility was selected to represent each of the four following states: Arizona, California, Colorado, and Nevada. The interview questions were organized into eight different categories: procurement, roles and responsibilities, risk and quality assurance, design, design review, cost and schedule estimates, submittal and submittal review, and communication and information flow. Findings include that all four utilities engage the design-builder before 10% of design completion. This study supports utilities interested in using DB and in identifying practices to improve their DB project performance.

Port Miami is one of the busiest cruise ship ports in the world, berthing larger cruise ships. Port Miami is facing water distribution system flow and pressure issues during cruise ship potable water filling activities. In addition, Port Miami is preparing for the arrival of the largest mega cruise ships in the world, which will only worsen the water flow and pressure issues, if they are not addressed prior to their arrival. This paper will detail the planning work completed by the Miami-Dade Water and Sewer Department and the Miami-Dade Seaport Department. In addition, it will review the subsequent activities to implement the planned water infrastructure and provide a status of the construction of the infrastructure and the arrival of the mega cruise ships. Hydraulic analyses were performed to identify transmission, distribution, and ship filling station improvements. Constructability was reviewed due to multiple ongoing construction projects as well as substantial subterranean structural components along the cruise ship wharf. This project included planning, utilizing one of the largest hydraulic models for one of the largest water systems in the U.S. It also included design coordination for various construction techniques, including microtunneling and horizontal directional drilling, due to a subaqueous crossing of Biscayne Bay, in Miami, Florida, and crossing of railways.

Managing buried assets and risk during construction activities is critical for utility owners. This study provides innovative engineering techniques to assess the risk of building a roadway over a pipeline. While traditional methods could have been employed for the project discussed in this study, the asset’s criticality deemed it a high-risk, thus managing the risk was key to delivering a successful project. This study describes the project background, pipeline, and method employed to manage the risk of the project. This study also provides a procedure to examine if a pipe, as originally designed, can withstand the new loading conditions generated from the construction activities and from the conditions that will prevail post-construction. The proposed method determines the maximum allowable live loads for the different amounts of earth cover. For the case study, a 1372-mm prestressed concrete cylinder pipe (PCCP) under 0.3, 0.7, and 1.5 meters of earth cover and construction loading was analyzed. The impact of construction activities on the PCCP was determined by monitoring the level of stresses and strains in the various components of the pipe during different construction loading while varying the number of broken prestressing wire wraps. Based upon the results obtained, the threshold depth of cover to satisfy the design requirement for undamaged pipes was calculated. Also, to prevent additional stress on the PCCP, the controlling threshold was considered as the micro-cracking limit which was developed by nonlinear finite element analysis (FEA). The micro-cracking limit mitigates the level of risk and diminishes the level of stresses to the PCCP with broken wire wraps during construction activities.

East Bay Municipal Utility District’s Sequoia Aqueduct is a 20-mile long 48-inch inside diameter reinforced concrete cylinder pipe (RCCP) constructed in 1929. The RCCP was manufactured by the Lock Joint Pipe Company. Connected to the aqueduct was a 24-inch diameter 1929 steel pipeline with an extensive leak history. In order to replace this pipeline while maintaining service, a 24-inch hot tap on the aqueduct was designed. AWWA Manual M9 for Concrete Pressure Pipe only recommends a strap-on prefabricated tapping saddle for tapping RCCP. This system requires a rubber gasket and grout to keep the joint watertight. Manual M9 explicitly does not recommend weld-on tapping assemblies citing concerns with damaging the steel cylinder during welding. However, a welded connection was designed and installed in order to achieve a zero leakage permanent connection. This paper describes the design details and construction requirements utilized to mitigate M9 concerns and make an improved flanged outlet.

Pipe materials represent one of the largest expenses of transmission projects, so many municipalities, river authorities, and water districts are considering pre-purchases as a way to save money. Freese and Nichols and Garney Construction worked together on three large projects in which the North Texas Municipal Water District (NTMWD) and Sabine River Authority (SRA) pre-purchased pipe early. Using these three case studies, this paper will examine the advantages and disadvantages of pre-purchasing pipe, so readers will understand the factors to consider when making that decision.

The history and development of the 2-layer polyethylene (PE) coating system and instances of its proven long-term use as an effective corrosion-protection coating will be covered. The 2-layer polyethylene (PE) coating system has been used in the oil, gas, and water industry for the past 48 years for potable, waste water, and water treatment for both steel and ductile iron (DI) pipe. Also addressed are mainline coatings and those utilized in conjunction using heat shrink sleeves and polyethylene tape coating systems for field joints. Examples will be given of application, installation, and long-term use as a corrosion protection layer for steel and DI pipe.

The Lafourche Parish Water District #1 (LPWD#1) has had an ongoing research project with the Ductile Iron Pipe Research Association (DIPRA) through the periodic evaluation of a four-inch cast iron water main in our system. Installed in 1958, it was the first known pipeline to use polyethylene encasement as a means of corrosion control. Over the past 60 years, the LPWD#1 has cooperated as DIPRA conducted field examinations of the pipe in an effort to evaluate the effectiveness of the film. In that time, some 10 investigations have been performed, with the most recent occurring in August 2018—after 60 years of service. Here, we summarize the results of those investigations, which culminated in the 60th-year investigation detailed in this report.

The paper presents the results of an analytical and experimental study performed to predict the impact of current and future expected degradations of the inner-core concrete, resulting from biochemical degradation due to exposure to lake water, on the structural performance and remaining service life of the Cedar Creek (CC) and Richland Chambers (RC) pipelines for Tarrant Regional Water District. Compression tests and petrographic examinations of the concrete inner core are performed to evaluate and quantify the extent of current degradation, strength, permeability, and quality of the inner core and the mortar coating. The biochemical degradation of the inner core is simulated in the STADIUM program and is used to predict the extent of future degradation in 50 to 100 years of additional service. The results are then used to evaluate the performance of the pipes under service load accounting for current and future degradation states. The remaining service life of the pipeline is found to depend on the mode of degradation and failure, including biochemical degradation of the inner core, degradation of mortar coating, and hydrogen embrittlement breaks of the wires. Each mode of failure is discussed, and mitigation measures needed for life extension are identified and discussed for each pipeline.

The new American Water Works Association (AWWA) standard C305 for carbon fiber reinforced polymer (CFRP) renewal and strengthening of prestressed concrete cylinder pipe (PCCP) has been approved by AWWA. The standard is based on load and resistance factor design for a service life expected for infrastructure. It provides requirements that ensure strength, durability, reliability, and weathertightness of CFRP during the entire service life of the liner on par with other construction materials. The paper will discuss the advantages of CFRP liner relative to other construction materials, provide a brief history of the development of the standard, discuss the purpose and scope of the standard, and review the major provisions of the standard for material system design, installation, and quality control and assurance of CFRP liner repair of distressed PCCPs or for strengthening PCCPs. It also presents a summary of the theoretical and experimental bases of the provisions. Although the standard is developed for PCCP, its provisions can be applied to other concrete pressure pipes. The standard enables utilities to use CFRP liners as a permanent repair technique.

Just imagine it is the dead of winter in Milwaukee, Wisconsin, and you are asked to repair eleven segments of dual 36-inch prestressed concrete cylinder pipe (PCCP) and have it completed and back in service in less than four weeks. A regional medical center in the area doesn’t have the budget to repair the whole line but needs the dual pipe system to last for another 20 years when the funds come available. The eleven segments were identified through non-destructive evaluation and deemed in need of rehabilitation to last the required 20 years. There are a multitude of trenchless rehabilitation solutions available (i.e. CIPP, spray in place, slip lining, etc.), but which one provides segmental repair option and can be completed within the owner’s compressed schedule? In the end, the use of carbon fiber reinforced polymers (CFRP) was selected as the ideal choice. This paper will examine the owner’s decision to use CFRP, the design process, and the successful installation of the CFRP system in the difficult conditions.

Tri-County Water Authority treats water and wholesales for cities and public water supply districts in Jackson, Cass, and Bates Counties in Missouri. The Water Treatment Plant and original transmission system were built in 1993, with expansions in 1999 and 2005. Further expansion began in 2015. This expansion included installing a parallel transmission main to an existing 16-inch ductile iron pipe main. Due to the frequency of failures with existing pipeline materials, Tri-County underwent a material selection process. The result of this process was Tri-County determined ductile iron pipe with polyethylene encasement would provide the overall best value for its customers. As design was nearing completion, Tri-County learned of zinc-coated ductile iron pipe and negotiated with a manufacturer to supply the pipe for use in known corrosive areas of the project. This paper will review the project and test results from corrosion monitoring equipment installed on the Tri-County pipeline in August 2016.

Corrosion is an electrochemical process involving the flow of electrons and ions between two metallic surfaces. For corrosion to be present four key parts are needed: an anode, a cathode, the surrounding electrolyte, and an electronic/metallic path. With buried metallic structures these four key parts are present and corrosion can occur. In an effort to control corrosion cathodic protection (CP) can be applied. Over the last year, Lockwood, Andrews, & Newnam Inc. (LAN) has designed multiple cathodic protection systems for large diameter transmission mains being built as part of the city of Houston’s (City) Surface Water Transmission Program (SWTP) to lengthen the lifetime of proposed metallic water lines and protect against external corrosion. This paper will discuss the typical process that these projects go through in designing the CP systems that were used, provide background information for the two common types of CP systems, and examples of challenges that were encountered during design. Discussions will include the expected design life of a system and how external corrosion can be prevented with a properly designed cathodic protection system.

Water main replacement programs in North America have been largely focused on cast and ductile iron water mains. It has been estimated that an investment of $0.5 trillion in the next 25 years and over $1 trillion in the next 40 is required to address end of useful life requirements for these systems. The capital cost of alternative lining programs can be very close to full replacement cost and the available technologies are still evolving. There is considerable need to develop more cost effective techniques for water main rehabilitation in conjunction with optimizing replacement and structural relining techniques. A unique addition to the rehabilitation “tool-box” should be the strategic use of CP retrofit techniques to mitigate failure rates and extend useful design life of existing mains. While the cost of this approach can be highly variable based on the logistics to access the mains; it is often only 5%–10% of the capital cost of replacement or fully structural liners with comparable failure reduction when the overall system effects are considered. The paper examines the technical approach for and the effectiveness of cathodic protection in Toronto, ON, Canada, based on 40 years of implementation.

Denver Water’s Jim Creek Siphon facility is a 52-inch diameter steel siphon installed in 1935. The above-ground siphon is exposed to extreme mountain weather conditions resulting in significant pipe material temperature fluctuations. The siphon is equipped with six expansion joints (EJs) to accommodate the thermal expansion and contraction effect that occurs. By 2018, the exposed EJs and original pipe were showing measurable signs of degradation. Denver Water performed a condition assessment of the entire siphon facility, including the EJs, which proved to be a challenging element of the system to assess. Denver Water needed to determine if it was reasonable to assume the expected life of the EJs should be similar to that of the pipe itself and if the EJs should be rehabilitated, replaced, or despite the visual degradation that was observed, if they were functioning adequately and taking no action was a viable alternative. A decision was made to replace the existing EJs and use the replacement effort as an opportunity to better understand the particulars of EJ degradation and performance issues. The goal was to develop more definitive replacement and rehabilitation triggers that could be applied to the numerous other EJs of the same style and vintage as those at the Jim Creek Siphon facility. This paper presents the results of Denver Water’s evaluation of the EJs on the Jim Creek Siphon facility which included measuring temperature and movement fluctuations, in situ interior and exterior inspection, and detailed post-demolition shop inspection. The effects of corrosion on EJ functionality were also considered. Recommendations for maintenance and triggers for replacement of exposed EJs in harsh environments will be presented.

King County’s Mercer and Enatai Interceptors were built in the 1960s and extend over 14,000 feet from Mercer Island into the Enatai neighborhood of Bellevue, Washington. The Interceptors primarily receive flows North Mercer Pump Station but also collect flows from the local city of Mercer Island and city of Bellevue sewer systems. Some parts of the system are reaching the end of their useful lives, and future peak flows are projected to exceed the system’s capacity shortly. After the county chartered the need to upgrade the existing interceptors, an in-depth alternative analysis and preliminary design process resulted in a new system design including three inverted siphon segments. This paper reviews the unique set of constraints and hydraulic design challenges presented by each of the siphons and discuss the different strategies and tools that were used to develop and evaluate the proposed solutions. Some of the key items that will be covered include: concept development, system design approach, sedimentation strategy, control structure design, steady state hydraulic modeling, air management review, and computational fluid dynamic modeling.

A 12-inch water line was identified to be installed along IH-10 East Freeway for 3,600 feet in Houston, Texas, to allow customer services to be transferred from an aging 42-inch prestressed concrete cylinder pipe (PCCP) that needs repairs. At Hunting Bayou, a 600-foot portion of the 12-inch water line was to be installed using horizontal directional drilling. One of the challenges that came with this crossing was to install the pipe in a limited work space without obstructing active driveways along one of Houston’s busiest roadways, the frontage road of IH-10. Therefore, the cartridge method using Certa-Lok C-900 RJIB (restrained joint integral bell) was specified during pullback. The directional drill effort encompassed the pilot hole and 2 reamed passes. As the pipe was being pulled the contractor engaged each joint one-by-one and pulled the first few joints within the hole. Shortly after a drill stem got stuck at the drilling machine. After the stem was removed the contractor successfully pulled the remaining pipe within hours.

The Cypress Waters Phase Two Lift Station and Force Main project involved the design and construction of a 9 million gallon per day (MGD) lift station and 15,000 linear feet of 24-inch high density polyethylene (HDPE) force main in far northwest Dallas near Dallas-Fort Worth (DFW) Airport. Approximately 4,000 linear feet of force main was installed in the median of Belt Line Road through the city of Coppell. In order to maintain traffic flow and minimize disruption to the roadway corridor, the force main was installed by horizontal directional drill (HDD) in four sections, each with its own set of unique challenges. Construction of the horizontal directional drills spanned 4 months and was completed in September 2017.

The city of Brantford constructed a curved microtunnel in challenging soil conditions to upgrade the existing Greenwich sanitary trunk sewer (STS) in 2018. The new sewer provides additional capacity for future growth in the downtown core and for a new recreational facility jointly developed by the city, the YMCA, and Laurier University. Identified in the 2014 City of Brantford Master Servicing Plan for sanitary sewers, and subsequently confirmed with the city’s sewer modelling consultant, this project includes upgrades to the existing sanitary trunk sewer between Clarence Street South and the Greenwich Street sewage pumping station. The existing Greenwich sanitary trunk sewer (STS) in the city of Brantford was upgraded to provide additional capacity for future growth in the downtown core. The new sanitary trunk sewer was installed via microtunnel construction on a curved alignment (radius 970 m) and crossing an active rail corridor. The final installed length of microtunnel was 430 m proceeding through mixed-face ground conditions. Robinson Consultants Inc., together with Aldea Engineering Services Ltd., prepared the design for the microtunnel that was subsequently constructed by Ward & Burke Microtunnelling. This paper explores the challenges faced during design and construction, and the innovative solutions developed by the contractor and the project team to successfully complete the project on time and within budget. The paper also evaluates the application of a geotechnical baseline report (GBR) in the form of GBR sheets to establish the contractual ground conditions, and how the actual ground conditions were reflected in the data logs recorded by the microtunnel boring machine (MTBM).

Combined effect of land subsidence and sea level rise poses a significant longterm threat of coastal land inundation. It jeopardizes infrastructure located in these areas. A detailed GIS method that adopts historical land elevation data of a region collected by a continuous monitoring and surveying network is discussed and detailed in this paper. Authors simulated the risks of land inundation for varying periods in future and identified at-risk infrastructure located in the affected area with the help of the GIS. The risks were forecasted for next 100 years, with 10-year increments starting from 2014. Some of the infrastructure assets located in some of the coastal areas of Gulf of Mexico were chosen as an example of at-risks assets for this study. Authorities such as state departments of transportation would use this approach in identifying the at-risk infrastructure and plan for their short-term and long-term response accordingly.

Citizens Energy Group (Citizens) is implementing a Long-Term Control Plan to address combined sewer overflows (CSOs) in Indianapolis, Indiana. The plan, referred to as “DigIndy”, includes provisions for a series of CSO diversion structures, consolidation sewers, drop shafts, and a tunnel for storage and conveyance. There are multiple tunnel segments as well as multiple near surface projects planned over a span of 10 years. The design and construction of the Pleasant Run PR02-DV-1 project faced challenges of construction in an urban environment around numerous utilities including existing water, sanitary, gas, and overhead electric utilities. Coordination with other municipal projects that were being planned, designed, and constructed concurrently was also a challenging aspect of the project during design. Additionally, coordination with multiple stakeholders and community neighborhoods, and managing project risks and schedule assisted with completing a successfully managed and executed project.

The City of Rehoboth Beach is required, under the terms of a consent order from the Dept. of Natural Resources, to eliminate the discharge of treated effluent from the Rehoboth Beach Wastewater Treatment Plant into the Lewes-Rehoboth Canal. The city, after detailed studies and the evaluation of all options, proposed an ocean outfall in order to comply with that order. On August 14, 2017, the Rehoboth Beach Commissioners unanimously approved awarding four bid packages to various contractors to begin construction on the ocean outfall project. The four bid packages were treatment plant improvements, effluent pump station, on-shore pipeline, and offshore pipeline including a diffuser to comply with the consent decree. This paper will discuss the purpose and design of the project including pipeline routing, construction alternatives, regulatory requirements, the construction season, and environmental concerns. The project design included pipeline routing, construction alternatives, and regulatory requirements. One of the biggest impacts to the project was the proposed construction season requiring the marine work to be completed in winter and the system operational by June 30, 2018. The winter of 2017–2018 was most notable for four nor’easters in March, which directly affected marine construction. The paper will conclude with a brief summary of construction details from the actual construction of the 6,000 feet of outfall including diffuser. Horizontal directional drilling was used to complete 3,800 feet of the outfall. Construction of the marine outfall commenced November 2017 and was completed before the June 30, 2018, deadline.

Advance rate (AR) estimation is a crucial factor at the conceptual phase of a pipeline project for preliminary estimation of tunnel boring machines’ (TBMs’) usage. The primary objective of this paper is to develop order of magnitude performance charts for advance rate of TBMs that can be used with limited information about the pipeline progress at the conceptual phase. The secondary objective of this paper is to evaluate factors that impact TBM progress in applications of tunneling for pipeline construction projects. Statistical analysis was used to produce an advance rate chart. The results were tested with use of case studies. The results of this paper showed that the highest amount of overestimation for case studies considered by these performance charts was 16%. The outcome of this paper can assist in prediction of tunnel boring machine’s advance rate at the conceptual stage of a pipeline project based on ground conditions and diameter of the pipe.

The city of Largo, Florida, with of approximately 85,000 residents, recently completed a $38 million wastewater collection system improvements project to eliminate sanitary sewer overflows (SSOs) that had regularly occurred following significant rain events. This Wet Weather Monitoring and Pumping System Project, involved construction of approximately 14.2 miles of sanitary force mains and the reconstruction and upgrade of seven pump stations. Following prequalifications and value engineering negotiations with the selected contractor, the project was awarded in early 2015 and placed into service in late 2016. One of the key challenges facing this project was the construction of a new force main traversing the city from east to west through urban and residential rights-of-way with dense utilities and multiple roadway and waterway crossings. Force main piping ranged from 12-inch to 30-inch diameter, of ductile iron and polyvinyl chloride construction, with installation by open cut, horizontal directional drilling (HDD), and jack and boring. Necessitated by wetlands and Florida Department of Transportation (FDOT) road crossings, roadway and driveway impacts, residential encroachment onto easements, and crowded utility/drainage corridors, twenty-five (25) separate HDDs were included in the pipeline route, totaling 5.6 miles of the pipeline—using fused polyvinyl chloride pipe (FPVCP). Drill design was based on pipe material selection, entry and exit location availability, layout and pullback requirements, bore path tracking capabilities, and geotechnical conditions. Details of individual drills are discussed, as well as significant issues experienced during construction, such as frac-outs, drilling mud management, and bore path tracking. The incorporation of trenchless methodologies such as horizontal directional drilling and jack and boring allowed the project to be completed successfully, with significantly less impact to the community and environment than open-cut options. The final product will reduce sanitary sewer overflows in the city of Largo for many years to come.

This case study will discuss the intricacies in planning, designing, permitting, and constructing a large-scale gravity sewer across the Dulles International Airport and with four tunneled crossings of the Washington Metropolitan Area Transportation Authority’s Metrorail Silverline (Phase 2). The sewer was designed to serve Loudoun Water in Loudoun County, VA. Located just west of Washington, DC, in one of the fastest growing areas in the country, this new sewer is needed to meet Loudoun’s projected wastewater demands in their Horsepen Run sewershed. This paper will outline the strategies implemented by the project team to facilitate and expedite stakeholders review and approval of the 20,000 linear-foot large diameter sewer (72/48/42 inch). In addition, the paper will outline how the scalable risk management strategy employed aided in maximizing value for Loudoun Water while minimizing risk.

Tunnel construction methods for large diameter water lines are evaluated on a case by case basis. More so for one of the largest potable water lines in the Houston Metro Area. The city of Houston is proposing to install a 108-inch water line from the Northeast Water Purification Plant to the west side of Houston, approximately 16 miles. Each tunnel along the alignment has its own challenges. Where cohesive soils were present, hand mining could be an alternative. If non-cohesive soils were present, or where mitigation of settlement was critical, tunneling using a closed face tunnel boring machine was preferred. An earth pressure balance machine (EPBM) was also considered at a few locations. One location appeared to require an EPBM since a saturated granular strata was encountered underneath an existing bridge. However, it was determined that subsurface chemical grouting in conjunction with a closed face tunnel boring machine (TBM) would better protect the bridge structure.

As one of Maryland's fastest-growing regions, Howard County, a suburb of the Baltimore/Washington, DC, metropolitan area, has seen a 34 percent increase in population over the past decade. Projected population will grow to 328,000 by 2035. As a result, and as a means of improving reliability, the Howard County Department of Public Works completed a capital project to install 3.15 miles of 36-inch Diameter Water Transmission Main in the Columbia area. The water main alignment selected includes two crossings of U.S. Route 29, consisting of 1,225 feet of micro-tunneling, two river crossings, and what was considered the most challenging aspect of the project, installation of 7,500 feet of water main under one of the busiest roads in the region.

To meet the fuel demands of the expanded Hong Kong International Airport (HKIA), new twin aviation fuel pipelines were installed using horizontal directional drilling (HDD) by Langfang Huayuan Mechanical and Electrical Engineering Co., Ltd. The new pipelines included two parallel pipes with drive lengths of 17,060 ft. (5.2 km) each, a diameter of 20” (508 mm), and a buried depth of 330 ft. (100 m) under the seabed. The $1.3 billion HKD ($165.63 million USD) project started in early 2016. The first pipe installation was completed on December 27, 2017, and the second on March 9, 2018. The overall project duration was 30 months, which included 6 months for onsite preparation and 4 months stoppage due to the breeding season of the egret, a small bird. The length set a world record for HDD. As expected, the pipeline installation experienced numerous difficulties and challenges including pilot hole directional control, drilling fluid management, reaming torque, pullback force, and project management. The contractor optimized HDD intersect technology with an innovative “handshake” pilot hole drill-bit for the crossing. Additionally, they also utilized a global position system (GPS), sea surface ship positioning system, and geomagnetic sensing system to accurately guide the pilot hole. In order to reduce the reaming torque, a series of unique specialty reamers were developed for the extra-long distance reaming process. Accordingly, the contractor used a novel high-performance drilling fluid to meet the requirements of cuttings transportation and borehole stability. During the pipe pullback process, a redesigned thruster was used to protect the anticorrosive coating of the steel pipes. Additionally, the modular equipment accelerated the construction period greatly. With the aid of innovation and key drilling parameters, the contractor completed the world’s longest HDD crossing project successfully. Experiences learned in this project can be used as the HDD industry continues to break distance records.