Pipelines 2005: Optimizing Pipeline Design, Operations, and Maintenance in Today's Economy

In order to analyze the fatigue life of mini-horizontal directional drilling (mini-HDD) rod, a fatigue test machine was constructed at the Trenchless Technology Center. This paper describes the testing procedure and the results of the testing. Five preliminary tests were carried out to test the equipment set up and during these tests, the strong impact of make up torque and joint lubrication on the fatigue life was observed. Seven tests were then carried out at different drill string curvatures to construct an S-N curve for mini-HDD drill pipe. During this series of tests, six failures occurred and one test was terminated without failure. The S-N curve derived from the test results was found to match well with prior research for larger drill pipe used in oil field drilling. Simulation of drill joints was carried out to investigate the stress concentrations within the joint and the theoretical stress condition in different phases of the drilling process was compared to the normal stress assumptions used in practice. The S-N curve results can be used to provide an indication of the cost of drill rod fatigue by using some illustrative assumptions about curved drilling and drill rod usage.

The Canyon Regional Water Authority, New Braunfels, Texas, planned for the construction of a major system expansion that included a combination of 35,242 feet (10,742m) of 24 inch (610mm) and 41,625 feet (12,687m) of 30 inch (762mm) ductile iron pipe. Along the planned route there were four (4) sections designed for installation using horizontal directional drilling (HDD). The originally designed HDD installations required transitions from ductile iron pipe to high-density polyethylene (HDPE), the perceived standard piping material for HDD. Having identified this material paradigm within the trenchless industry, the successful bidding contractor approached the Engineer to request a material change for the HDD portions of the new transmission system. Informed about the suitability of ductile iron pipe for trenchless installation, a submittal was initiated which proposed that the HDPE pipe be replaced with flexible restrained joint ductile iron pipe for the HDD portions of the project. This requested change was thoroughly evaluated by the Owner and Engineer, whose affirmative decisions to proceed started the momentum of this paradigm shift. This paper will discuss the process by which the material change was evaluated from an engineering perspective, and from the perspective of the installing contractors, and the constructibility issues with installing ductile iron pipe by HDD.

Many countries have long had the desire to move their overhead power lines to the underground due to increasing pressure from environmentalists, increasing pressure from city planners, losses from frequent outage, loss from bad weather, high cost of maintenance, high transmission loss, electrocution, bushfire risks, high greenhouse emission, auto accidents, cost of tree pruning, better aesthetics, and better real estate value. Cost and the underground already being so crowded with water pipes, sewers, storm drains, gas mains, telephone cables, and other conduits have prevented the power companies from realizing this goal. While the power industry has felt this way, the communications industry is fighting for its survival. It appears these two industries could work together for both of them to gain. Deployment of optical fiber networks or power distribution networks underground in dedicated conduits requires extensive construction, usually involving excavation of city streets. It makes all the sense in the world to locate the power distribution cables and the fiber cables in the existing rights of way on sewers, water mains, gas pipes, tunnels, and other underground structures to move them underground quicker and at a cheaper cost. This paper provides an account of how to go about deploying power and fiber cables either inside or outside of existing utility pipes using trenchless technologies. Tokyo, Taipei, Berlin, Hamburg, Paris, Toronto, Vienna, Boston, New York, Albuquerque, and Indianapolis, are among the growing list of progressive cities where such creative business partnerships have produced unprecedented financial results to all parties concerned. An overview of details of such creative business partnerships where the same existing conduits were used toward win-win situations for all parties involved around the world will be presented along with the results of a global survey of underground power distribution practices. Standardization efforts and workable solutions to technical problems also are given.

Timely management of day-to-day activities is vital to the successful construction of a pipeline project. This paper will discuss how decisions made during each project phase are used to determine if the project should continue to the next level. It will also demonstrate how pipeline projects can be divided into more manageable components. Key elements during planning and design will be presented, including project structure, defined deliverables, management controls, and external influences/sources. A structured project process can minimize lost effort and cost, allowing each phase to be properly screened to address the issues that can cause delays, extra costs, or even project termination. Pipeline projects require extensive coordination with external sources, which can cause alternatives to be considered that, could impact previous decisions and influence the final project result. Specific controls during each project phase will help manage the interrelationship of property acquisitions, regulatory agency requirements, and project design. The systematic approach to planning and design can be organized into separate, but interdependent, phases structured to minimize risk and enhance project success. Each phase will involve several multi-functional reviews, but will also need to be transitioned to minimize its effect on project momentum. This paper will discuss deliverables and criteria for each phase, including estimates, schedules, health and safety, construction documents, constructability reviews, procurement and start-up planning. These activities and deliverables can be structured so that the specific steps taken will identify the necessary decisions to make a "go" or "no-go" judgment for the next phase. The subject matter included in this paper will identify the project phases and the key decisions appropriate for each phase. Conference attendees will learn what makes a project successful beyond the feasibility stage.

The North Texas Municipal Water District (NTMWD) is a wholesale supplier that supplies treated water to one million people in four counties on the northern and eastern boundaries of the Dallas/Fort Worth metroplex. The communities of McKinney, Frisco, Little Elm and Prosper are in the NTMWD's north sub-system. The growth rate for these communities has skyrocketed in recent years necessitating an expansion of the treated water delivery system. The Frisco-McKinney Pipeline is an $18 million project currently under construction that will provide water to these communities. The pipeline project includes four miles of 60 in. (152 cm) and nine miles of 48 in. (122 cm) pipe to serve six new delivery points in the NTMWD system. The pipeline project was divided into three contracts to condense the construction schedule. Polyurethane coated steel pipe was the low bid alternative for the 60 in. pipe while bar-wrapped pipe was low for the 48 in. pipeline sections. The paper presents several problems and lessons learned encountered during the design and construction phase of the project, including the following: (1) Pro's and con's of locating the pipeline route in the ROW of a developing thoroughfare versus a private easement; (2) writing polyurethane coating specifications that produce a better end product for your client; (3) design considerations for steel pipe; (4) Weighing the costs and benefits of sub-surface utility engineering; and (5) Considerations for tunnel design.

The Manning Equation is an empirical formula commonly used to design sewer systems. Most design methods assume that the roughness coefficient is constant, but historical research suggests that it actually varies as a function of flow depth. Therefore, a constant or varying roughness coefficient is selected at the discretion of the design engineer. The same consideration applies to scattergraph methods that correlate the Manning Equation to flow monitoring data. Regressive methods, such as the Lanfear-Coll Method and the Stevens-Schutzbach Method, have been previously reported using a constant roughness coefficient. A modification is presented to incorporate a varying roughness coefficient into these methods. The selection of a constant or varying roughness coefficient can impact sewer capacity estimates by over 20%. Examples of regressive methods using a constant and varying roughness coefficient are provided from flow monitoring locations throughout the United States. Laboratory research by the authors is also provided and demonstrates that the use of a varying roughness coefficient provides a more accurate determination of sewer capacity.

In the Pipe-in-pipe (PIP) system, stress transfer takes place through the annular space, so that the material used as insulator in the annular space should posses good bonding strength to keep both pipes in position during installation in deep-water. One way to quantify this bonding shear strength is by the single lap shear tests. In this study, the effect of coarse aggregates [<19.1 mm (0.752 inch)], sand [<5 mm (0.2 inch)] and microspheres [<0.2 mm (0.008 inch)] on the bonding shear strength of a polyurethane based polymer grout was investigated. The shear bonding strength between the grout material and steel was determined using the single lap configuration. The maximum bonding shear strength of polymer-aggregate and polymer-sand composite were 1.8 MPa (260 psi) and 2 MPa (285 psi) respectively, with 60% of fillers (by weight) in the polymer composite. Addition of aggregate and sand improved the bonding strength. A finite element analysis was used to investigate the parameters that influence the shear stress distribution in the test configuration and the results were compared to the Volkersen's analytical solution. Effect of modulus, lap length and lap thickness on the shear stress distribution was investigated.

Finite element analyses are carried out on 3D full tunnel excavation for both New Austrian Tunneling Method (NATM) and Tunnel Boring Machine (TBM) using the elastoplastic subloading t_ij model. The effect of ground characteristics on surface settlement and earth pressure is investigated considering two ground types. Two excavation sequences are also considered to investigate the influence of excavation sequences in tunneling. It is revealed that for a given ground type, the excavation sequence did not affect significantly the final settlement trough. However, final settlement is much dependent on the soil characteristics. In TBM, tunnel excavation is simulated considering soil-water coupled analysis. Two excavation rates are employed in the simulations to investigate the influence of excavation rate on ground movement. It is demonstrated that surface settlement depends on the excavation rate that is employed during construction, and the ground settles continuously even after completion of the tunnel excavation due to the dissipation of pore water pressure.

This paper presents New Jersey American Water Company's (NJAW) evaluation and management program for prestressed concrete cylinder pipe (PCCP) assets within the Elizabethtown service area of New Jersey. The goals of the PCCP Asset Management Program are to determine the present condition, level of distress and potential risk of failure of the PCCP mains throughout the water system, and to recommend methods of rehabilitation. The results of the 2004 PCCP Monitoring Program are also discussed.

Water, sewer and storm pipeline systems are a major capital investment and utilities must ensure they are properly maintained if they are to perform as desired. Pipelines can account for the largest percentage of capital investment and a significant portion of the operating cost investment. Due to their typically long life cycle and expensive renovation costs, proper planning for pipeline reinvestment can improve the financial health of a utility and provide for effective continuous service. Various methods have been proposed to evaluate reinvestment needs for pipeline assets including general rules of thumb supplemented by experience, survival functions, and condition matrices. Pipeline deterioration can be a result of damage caused by adjacent construction activities, weather, ground movement, vandalism and normal wear and tear. Regardless of the reason for pipeline deterioration, a sound condition assessment program can identify pipeline assets that require repair or replacement. In order to fully leverage condition assessment data, it is important that the projection of reinvestment consider the data collected from inspection. In this way new pipe that is "acting" old and old pipe that is "acting" new can be properly evaluated as to the financial requirement to maintain the pipe in good working order. This paper discusses various aspects of reinvestment planning and the use of condition assessment data in a utilities reinvestment program.

Utility managers have begun to focus on asset management approaches to optimize the management of their collection systems, due to a number of drivers including the requirements of GASB 34, regulatory agency focus on sanitary sewer overflows and aging of their infrastructure. The Water Environment Research Foundation has developed or is developing a number of tools to help utility managers with these efforts. This paper presents information on innovative methods to inspect collection systems, methods to prioritize the collection system inspection process and protocols under development for condition assessment, among other tools available to utilities implementing asset management approaches to better manage their collection systems.

Trenchless construction methods have been successfully utilized to install numerous types of underground utilities while minimizing disruption to the general public and reducing associated project risks. The planning and design of trenchless construction methods for the installation of high-voltage (up to 345,000-volt) cable systems require unique considerations unlike the installation of water, sanitary, and telecommunication utility installations. Since high-voltage cables are designed to operate at 90°C, pipe temperatures are higher than for other systems. The earth's thermal properties also affect cable rating; and the separation between bores and pipe material selection may be governed by thermal considerations. The maximum installation length may also be limited not by the capabilities of the trenchless construction method selected but governed by the cable shipping lengths. This paper will discuss through actual project case studies the design and construction requirements that are unique to high-voltage electric installations. The paper will also include lessons learned from recent project examples and the factors which contributed to each project's successful use of trenchless methods when installing high-voltage cable systems.

During the early morning hours of June 8, 2004, a prestressed concrete cylinder pipe (PCCP) installed in 1991 through 1992 suffered a catastrophic failure. This failure occurred in a pipe section of existing 42-inch (1,067 mm) water line, which supplies potable surface water to Sims Bayou Pump Station in Houston, Texas. Several residential properties were flooded as a result of the failure. The City of Houston (City) authorized Lockwood, Andrews & Newnam, Inc. (LAN), to assist in the failure assessment and to design the repair for the water line. LAN performed a visual inspection of the water line interior around the failure location, and performed testing on wire and mortar samples. Initial test results and observations of the failed pipe section revealed that severe cracking existed in both mortar lining and coating, the prestressing wire did not exhibit signs of hydrogen embrittlement; however, the wire did exhibit severe corrosion, which may have facilitated the onset of failure. Further inspection revealed that the internal cracking appeared consistently at invert, crown and both springlines for a distance of approximately 26,000 linear feet from the pump station. Due to the risk of collateral damage should a second failure occur, LAN and the City determined that the line would not be placed back in service without extensive rehabilitation. Because this line is the only source of surface water to the area, groundwater wells were brought online. These wells were required to operate at full capacity in order to supply the demand during the outage of the line, and hydraulic modeling indicated that the groundwater wells alone were not sufficient to meet the summer peak water demands in the area. Therefore, LAN and the City were faced with the task of rehabilitating 26,000 linear feet of 42-inch water line and safely returning it to service before Summer 2005. This paper presents the options, cost estimates and schedules evaluated to fast-track the rehabilitation. The evaluation led to the conclusion that the most feasible solution was to perform design to slipline the existing line and provide bid-ready documents within two-months, allowing approximately six months to construct the improvements to the 5 mile stretch of water line. The paper will also discuss some of the lessons learned as the project went to construction.

How can a water utility construct a 30-mile pipeline project through various adverse conditions with limited funding that is spread over ten years? This paper will address the approach chosen by the City of Greeley, Colorado. Challenges such as steel pricing volatility, negotiating fair right of way crossing fees, easement acquisition, pressure testing and disinfecting the various pipe segments and contractor pre-qualification will be addressed.

Tarrant Regional Water District (TRWD) supplies raw water to over thirty wholesale customers (approximately 1.6 million people) in ten Texas counties. TRWD's existing raw water supply system includes two major reservoirs in East Texas, pipelines and pump stations to deliver water from East Texas to Tarrant County, the West Fork reservoirs, two terminal storage lakes in Tarrant County, and the Benbrook Connection, which delivers East Texas water to the southwest side of Fort Worth. The Eagle Mountain Connection Project will allow TRWD to pump water from their East Texas Reservoirs to Eagle Mountain Lake, which is one of the West Fork reservoirs. The $130-million project will allow TRWD to meet increasing demands in their West Fork service area and will result in power cost savings while increasing the available yield of the TRWD water supplies and the reliability of the TRWD system. The project includes 19 miles of 96-inch (244-cm) and 84-inch (213-cm) pipeline to connect TRWD's East Texas System to their West Fork System, two booster pump stations, a 120-million-gallon balancing reservoir, and a number of other required facilities. This paper presents a project update and lessons learned from the System Reliability and Enhancement Study, Pipeline Route Studies, Operational Study, and Preliminary. Design Phases of the project. The project is currently in the Final Design Phase. Construction is scheduled to begin in May 2006.

An improvement of the internal geometry of a three-dimensional control valve with complex geometry is carried out by the authors, in order to obtain a better hydrodynamic behaviour of the flow through the valve. A Computational Fluid Dynamic simulation is used to model it and to avoid the manufacture of the intermediate geometries. This research is a continuation of a previous study where the model and procedure for analyzing a control valve using CFD were validated using experimental data. The characteristics of this model were carefully defined and a standard k-ε turbulence model was finally chosen. The final CFD model used predicts accurately the flow behaviour through the valve in both open and pressure regulation valve situations. Cavitation is also investigated in order to obtain the most affected areas inside the valve.

The force transfer mechanisms in the pipe-in-pipe (PIP) system during installation and operation are of interest in order to protect the electrical heating tabs (connections). One method of achieving the optimum PIP configuration is to fill the annular space with quality dielectric grout. In this study, the behavior of PIP with pipes of 10 in. (25.4 cm) and 16 in. (40.6 cm) diameters held together by various grouts in the annular space was investigated. In order to screen the grouts and understand the interaction between the grouts and the pipes, a small scaled model test was used to characterize the shear bonding strength developed by the grouts under various curing conditions. Three grouts with and without aggregates were tested. Limited full-scale tests were performed to verify the model test results. The model test results showed that Grout-1 (with aggregate), Grout-2 and Grout-3 had good bonding strength in the PIP configuration. The average PIP capacities for Grout-1 with aggregate, Grout-2 and Grout-3 were 71,300 lb/ft (1,040,980 kN/m), 106,600 lb/ft (1,556,360 kN/m), and 115,450 lb/ft (1,685,570 kN/m) respectively. The PIP load capacity from the full-scale tests was higher than the average PIP load capacities from the model tests because the end effects were smaller in the full-scale tests than in the model tests.

Storm sewers construction often falls on the critical path of highway construction schedule and any delays can disrupt project schedule and also increases chances of traffic jam especially in urbanized areas. This paper proposes accurate ways of estimating the production rates of reinforced concrete pipe and precast concrete box culverts in order to improve the accuracy of project schedule and reduce inconvenience to highway users. Literature reviews are first used to identify the candidate drivers that affect the production rates of these storm sewers structures. Field construction data related to this research were collected from forty-four Texas highway projects between 2002 and 2004. Regression analysis, modeling and box plots were used to identify production rate drivers' relationships with productivity. Different production rate drivers were first identified using ANOVA test and box-plots and significant drivers were used to develop production rates models for design engineers to be used at the design stage. Research found that production rate of pipes was driven by Work Zone Accessibility, Length of run and Pipe orientation while production rate of culverts was driven by Length of run, Soil Type and Clay content in soil. Statistical models were also developed for these factors to allow project planners better estimate project schedules.

A Risk Based management system has been developed to optimize the maintenance and repair process of PCCP and provide decision-makers with objective information on the condition of the pipeline infrastructure. The system is based on a pipe deterioration model calibrated from inspection and monitoring data. This paper focus on the practical results of the system on a large scale application in Libya and shows how the risk based management process allows large savings on the maintenance expenditures.

A majority of the concrete pressure pipe that has been manufactured and installed in the United States is less than 48 inches (1200mm) in diameter. Depending on the design requirements, Embedded and Lined Cylinder Pipe (AWWA 301) and Bar Wrapped Pipe (AWWA 303) are commonly used in this size. However, the mechanical behavior and failure mechanisms of Prestressed Concrete Cylinder Pipe (PCCP) and Bar Wrapped Pipe are different. Nonetheless, three distinct assessment tools designed to detect broken wires (or bars) or leakage are useful for understanding the condition of these high value assets.

Two Water Transmission Pipelines owned and operated by the City of Everett, Washington, were installed in 1960 and 1966 using open cut methods. The pipelines cross under several rivers, creeks and sloughs, including the Snohomish River, Pilchuck River and Ebey Slough. The respective inside diameters of these pipelines are 48/42 and 51 inches [122/106 and 130 cm] and the estimated soil cover ranges from 2 to 8 feet [0.5 to 2.5 m]. Over time, changes have occurred in the rivers and slough that have resulted in the erosion of the soil cover above five pipeline crossings, resulting in the partial exposure and damage of the pipelines at these crossings. Since the City has plans for an additional 40 years of use for Pipelines, it was necessary to evaluate the scour potential and its impact on these pipelines. As a critical outcome, two of the five pipeline crossings were found to be in need of immediate repairs and were repaired as emergency projects, while other three crossings will be repaired as non-emergency projects. This paper describes the scour analysis approach, methods used, and results obtained for the two emergency projects.

Exploratory tunnels are commonly used for examining the geotechnical and structural aspects of proposed tunnel alignments. This paper explores the utilization of exploratory tunnels as a project management tool for estimating the cost and duration of construction for the entire project. Data were collected from the Kaponig 2.75 kilometers exploratory tunnel, a part of a double-track high-speed railway development in Austria. This knowledge and experience was used to evaluate the risks associated with design details for the final tunnel enlargement (alignment and grade, support requirements and excavation methods). A deterministic model based on Monte-Carlo simulation was developed capable of predicting potential outcomes of the total project in terms of cost and duration and their associated probabilities.

The City of Baton Rouge and Parish of East Baton Rouge (C/P) has entered into a mandated consent decree with the United States Environmental Protection Agency (EPA) and Louisiana Department of Environmental Quality (LDEQ) for violations against the Clean Water Act (CWA). As a result, the C/P implemented a Sanitary Sewer Overflow Corrective Action Plan (SSO CAP) to develop a program to reduce sanitary sewer overflows (SSO) within the C/P collection system. The primary method to reduce the SSO's of the program included increasing capacity, storage, deep gravity tunnel systems, and ballasted flocculation units. CDM is responsible for designing the Central Service Area Trunk Tunnel (CSATT) project, which collects flow from 12 pump stations and transfers those flows to a central pump station through a deep gravity tunnel network. The design of the central pump station and forcemain is the responsibility of another design team. A major challenge for both design teams entailed collecting flows from the east, delivering them to the central pump station and back west to wastewater treatment plant. Compounding the difficulty was that the alignment would either have to pass through several highly traveled roadways, along an Interstate 10, or adjacent to a railroad tracks. After performing a route alternative analysis and several design meetings with the client and pump station design team, a combined tunnel approach was recommended to minimize the surface disruptions and reduce the overall costs of the entire program. The new tunnel will be enlarged to house the gravity line leading into the pump station in addition the twin forcemains carrying the flows back to the wastewater treatment plant. Currently the tunnel is estimated to be approximately 3048 mm (120 inches) in internal diameter housing a 1067 mm (42 inch) gravity line, a 762 mm (30 inch) diameter forcemain, and a 1067 mm (42 inch) diameter forcemain for approximately 2530 m (8300 feet). During final design several of the following critical design issues along the alignment will need to be addressed 1) the location of the shafts along the highly traveled roadways, 2) potential settlement effects on a pile supported portion of Interstate-10, 3) potential settlement effects on a elevated water tank supported on a shallow foundation, and 4) under a man made lake.

This paper is a documentation of the progress of the tunneling project and includes a description of the project, geotechnical information, and concludes with a summary of the variances to plan.

The construction of large diameter pipelines is a large investment for any water utility. Achieving a quality construction project is critical to the overall performance and reliability of any water transmission system. Quality construction can also insure a longer service life for the pipeline. Therefore, the quality of the constructed pipeline is critical to the success of any water utility. The construction inspection of large diameter pipelines offers many challenges to the Owner's construction inspection teams. Large diameter pipelines typically use more complex pipe materials, bedding and backfill materials, appurtenances, corrosion protection requirements, and construction methods than do smaller diameter pipelines. Often the subtle differences between large diameter pipelines and small diameter pipelines are overlooked by inexperienced inspection teams. This paper includes an explanation of the critical components of large diameter pipeline inspection, and includes a convenient checklist for the field inspectors. The inspection checklist was developed from the author's pipeline design projects, as well as forensic engineering of pipeline failures. The paper focuses on the use of large diameter steel and concrete cylinder pipelines for water transmission service. The checklists cover important inspection and testing procedures such as right-of-way clearing and restoration; pipe handling; pipe material inspection before installation; trenching; pipe-laying; bedding and embedment around the pipe; backfill over the pipeline; internal pipe inspection after installation; inspection of appurtenances; patching of coating and lining; installation through tunnels; and hydrostatic, compaction, and non-destructive testing of pipelines.

The Interconnect Pipeline Project is one of three projects that make up the San Antonio Water System (SAWS) Interconnect Program. CH2M HILL was the designer for the Interconnect Pipeline Project and also provided construction inspection services. This project and two others were combined into a single active construction program for which CH2M HILL was selected to provide construction management services. The Interconnect project includes construction of a 16,300 foot (4,968m) 90-inch (228cm) raw wastewater transfer pipeline, a 13,500 foot (4,115m) 36-inch (91cm) recycled water line and 20,000 feet (6,096m) of fiber optic cable. The second project, the Interconnect Modifications Part B, includes raw wastewater connections at the Salado Creek WRC and the Dos Rios WRC. The third, the Dos Rios Recycled Water Pump Station Project, consists of a recycled water pump station at the Dos Rios WRC, and a recycled water pipeline terminal connection at the Salado Creek WRC. The primary purpose of this project is to link the Salado Creek WRC and the Dos Rios WRC together to optimize future operations. The project will allow the transport of raw wastewater to the Dos Rios WRC from the Salado Creek sewershed. At present, the Dos Rios WRC has excess treatment capacity. The link will allow SAWS to decommission the Salado Creek WRC, thereby saving approximately $5 million per year in operating costs. The recycled water pipeline will permit the use of Dos Rios WRC treated wastewater in the San Antonio recycled water system. This will maximize the yield of recycled water from SAWS' wastewater treatment facilities. The fiber optic carrier included in the Salado to Dos Rios Interconnect Project will provide for the future Installation of DCS between the two water recycling centers.

This study documents a series of eight trials of the weld-after backfill (W-A-B) sequence. This sequence of pipeline construction was first used in the late 1980's on a pipeline in Texas. Since then, more than 45 major pipeline projects in the United States have been constructed using W-A-B. These projects included a variety of pipe joint coating materials such as mortar diapers, concrete encasement, tape coatings and heat-shrinkable sleeves. This study focuses on heat-shrinkable sleeves for coating the pipe joint, prior to backfill. A growing practice in steel water pipeline construction entails fitting bell & spigot pipe segments together, installing field joint coatings and backfilling the pipe prior to welding. Welding is then completed from the inside of the pipe after the pipe has been backfilled. Weld-after-backfill has proven to be successful in minimizing the length of open trench, improving project safety and speeding up pipeline laying, resulting in design, economic and safety advantages over traditional steel water pipeline construction methods. These advantages benefit the owner, designer, contractors and suppliers. W-A-B is recommended for projects with lap welded joints, which is the predominant joint design for most water pipeline installations. The welding process, however, produces high temperatures on the pipe wall, which may damage some corrosion coatings. Research by Northwest Pipe, National Welding and Canusa-CPS was completed to evaluate various welding processes, measure temperatures and assess the affects of the W-A-B sequence on exterior field joint coatings. Various heat-shrinkable sleeve-coating systems were tested in order to optimize currect practices. This paper describes the W-A-B sequence, explains typical installation and welding processes, provides data from the research and makes recommendation as to best practices when this construction method is used.

Centrifuge modeling affords a useful tool to study the effects of explosions, since a small quantity of explosives can be used at higher gravity to cause the same effects as a larger quantity under normal gravity. This permits researchers to study the effects of a large explosion on prototype scale, through experiments that use smaller explosives, using scaled models of actual structures. In the subject study, experiments were conducted at 70 g on a geotechnical centrifuge. Models of underground structures (pipelines and tunnels) were buried at two different depths below the ground surface, within model containers. Controlled explosions were conducted at the ground surface, both directly above the model structure, as well as away from the structure. The effects of explosions on the structure were recorded in the form of strain measurements taken at different locations of the underground structures at different times—before, during, and after the explosions. Results of the data from these experiments provide valuable understanding of the effects of surface blasts. The results will be useful in designing new underground pipelines and runnels as well as for developing protective retrofits for existing structures.

Pipe-in-Pipe (PIP) configuration is considered as a practical solution to deep-water oil production to prevent hydrate formation and paraffin deposition during the transportation of crude oil to production facilities. The grout material used in the annular space in the PIP configuration must be a good insulator. On the other hand for Geothermal Heat Pump systems (GHPS), the grout material has to promote the heat transfer between the heat exchanger and the surrounding media and hence must be a good conductor. Along with thermal conductivity aspect, these applications demand higher bonding shear strength for stress transfer as well as to minimize heat transfer because of contact resistance. Hence, there is interest in developing grouting materials with varying thermal and bonding properties for onshore and offshore applications. The overall objective of this study was to investigate the effects of various fillers on the thermal conductivity of a polyurethane based polymer grout for PIP application and cementitious materials for GHP systems. Hot wire method was used to measure thermal conductivity. Effect of fillers on the thermal conductivity of materials were quantified. The average transient thermal conductivity of polymer was 0.091 W/mK, which was reduced with the addition of microspheres and increased with the addition of aggregates and sand. Thermal conductivity of cementitious materials was studied with curing time and it was observed that thermal conductivity decreases with time. Along with cement paste and mortar, carbon fiber reinforced cement mortar (CFRCM), concrete, self compacting concrete (SCC) were studied. The effect of adding bentonite on the thermal properties of SCC was investigated.

In 2000, the Howard County Bureau of Engineering implemented an acoustic monitoring program to evaluate the condition of approximately 18 miles of prestressed concrete cylinder pipe (PCCP). Over the last five years, various sections of the prestressed pipe inventory have been monitored for a minimum of three months. The SoundPrint acoustic monitoring system has successfully recorded and located a number of wire breaks along distressed sections of the prestressed inventory, including a portion of the Toll House Road 42-inch transmission main. The increased level of wire breaks recorded along this reach of pipeline led to an emergency pipe replacement program in 2004/05. This paper describes the development, testing, application and results of a continuous acoustic monitoring system used to detect and locate corrosion-induced failures in approximately 6,000 feet of the Toll House and Ridge Rd. 42-inch prestressed concrete pipeline. Also discussed are the results of the acoustic monitoring program and subsequent excavation to confirm deterioration measured by the SoundPrint monitoring system.

The use of electromagnetic techniques for the inspection and determination of distress (broken wires) for Prestressed Concrete Cylinder Pipe (PCCP) has greatly increased over the past 7 years. There are two primary providers of these services that use generically similar methods. Individually the results from each provider have been investigated with mixed results. Direct comparison of results between the two providers and confirmation of the results by excavation had not been performed before. As part of an AWWA Research Foundation study (Romer, 2004), comparisons of the results between the two electromagnetic inspection providers were made on several PCCP pipelines. Correlation between the two electromagnetic inspection results was modest. However, excavation for direct physical examination of the pipes to verify the predicted distress, or lack of distress, was not possible at the time of the electromagnetic inspections. The opportunity to directly compare and confirm the accuracy of inferred prestressing wire damage was finally possible on one of the San Diego County Water Authority's (Water Authority) pipelines. Both providers of electromagnetic inspection services had surveyed the same segment of the pipeline with differing results. Direct comparison of electromagnetic results with actual observed distress has been determined at several locations. This paper reviews the results and documents the predicted electromagnetic results along with the observed physical condition of the pipe sections and emphasizes the importance of proper records and the utilization of other impact factors that affect the performance.

In 1890, Galveston, Texas, was a lively, booming, prosperous seaport with a population of more than 23,000. Being one of the richest ports in the country, Galveston was Texas's gulf coast jewel. With economy and prosperity came popularity, and more and more people were moving to the Island. As development increased, so did the need for the proper infrastructure to support it. Since then, the water supply has been piped to Galveston via large cast iron water lines stretching (under the Galveston Intracoastal Waterway) from the Texas mainland to Galveston Island. Back in 1890, states were still allowed to regulate all construction within their waterways regardless of how it interfered with waterway navigation. In an attempt to support trade, Congress passed the Rivers and Harbors Act of 1899 to give the United States Army Corps of Engineers authority over all construction within navigable waterways, including the power to demand the removal of any abandoned or out of service pipelines. This paper will the detail the story of a 100 year old water line from the time it served Galveston during its peak boom years to today, where it lies abandoned and currently serves as the focal point of a local and federal debate over its future existence. This is an outline of the history of the waterline, an explanation of the conflict over its abandonment, and a contemplation of its future and significance.

Two major water supply pipelines, (48/42 and 51-inch [122/106 and 130 cm] diameter), owned by City of Everett, Washington, at five river and slough crossings (160 to 540 feet [50 to 165 m] wide) where parts of the pipelines had become exposed and unsupported because of scour. Two of the 51-inch [130 cm] diameter pipeline crossings required emergency repair. The underwater emergency repair consisted of repairing the damaged coating, driving steel piles alongside the sections of pipe that could be scoured, encasing the pipe in steel jackets at pile locations, bolting the jackets to the pipe and piles, and protecting the pipe by under-water tube steel fabricated screens and above-water rock-filled polyethylene mattresses. All investigation, scour analysis, design, procurement and fabrication were completed within 6 weeks. The mobilization of construction equipment on four barges at two sites and the emergency repairs at both crossings were performed simultaneously within 20 days to complete the construction prior to the impending flood season. This paper presents the structural evaluation, design of the emergency repairs, environmental aspects of the underwater construction, preparation of the construction documents, and the construction of the structural repairs to the pipeline.

The City of Houston, TX has had three major failures in its large diameter water transmission lines over the last few years. Such failures have required immediate action in order to meet high water demands and to maintain the system's integrity. The first incident involved a puncture inflicted by a drilling contractor in a 96-in (244-cm) water main located in an adjacent city. The pipe was patched from the inside and service was restored within 72 hours. The second incident was the catastrophic failure of a 60-in (152-cm) Prestressed Concrete Cylinder Pipe (PCCP) in the Central Business District (CBD). It was necessary to remedy the situation before the high-demand summer months to avoid significant system pressure reductions. The third failure occurred on a 42-in (107-cm) PCCP line. Because the line was essential to meeting summer demands, a sliplining procedure was used to fix the pipe in time. These instances of failures on water mains, for which the City relies considerably for supply, provide several lessons for the design process. It is important that damage is prevented by providing record drawings of water mains to appropriate government entities, by posting markers, and by monitoring corrosion and pipe defects. Also, the City should prepare contingency plans in the event of the loss of a major transmission main or facility. While handling the three water main failures mentioned, the City and its engineering consultant, Lockwood, Andrews, & Newnam, Inc., developed an innovative plan for handling the need for emergency repairs.

Rainfall from October 15–19, 1994 produced a flood of major proportions on the San Jacinto River in Harris County, Texas. On the morning of October 20, the surface of the river from the I-10 Bridge over the San Jacinto River to the Rio Villa subdivision just north of Wallisville road suddenly burst into flames. West of the subdivision on the south side of the San Jacinto River, at a distance of a few hundred feet, was a corridor of four pipelines running parallel to the river (a 20 in. O. D. (508 mm) crude oil, a 36 in. O. D. (914mm) diesel pipeline, a 40 in. O. D. (1016 mm) gasoline pipeline, and 12¾ in. O. D. (324 mm) natural gas pipeline). These pipelines were one by one succumbing to the forces of the floodwaters. First the crude oil pipeline broke and began spreading its contents on the waters. At 8:30 am the gasoline pipeline failed, releasing its contents on the water with the crude oil. When this volatile product reached an ignition source, the surface of the river erupted in flames. At 3:20 pm the diesel pipeline likewise failed, and the fire ignited its contents. At 3:45 pm the natural gas pipeline failed and its contents were ignited by the fire. A U.S. Geological Survey report, in January 1995 reported a record flow in the San Jacinto River just above the study area of the pipeline failures as having a measured current velocity of 15+ feet per second (fps) (4.6 meters per second, mps) on October 19, 1994. Three days after the breaks, measurements taken by divers recorded velocities of 12 fps (3.7 mps) at the location of the pipeline crossings of the San Jacinto River. A detailed forensic investigation was conducted to determine the cause of the failures. It was assumed that oscillations and hydrodynamic loads were imposed on the pipelines by the varying current velocities and combined with the unsupported span lengths caused stresses that resulted in a fatigue failure of each pipeline. Computations and analyses were made for steel pipe with the characteristics of; 1) a 36 in. O.D. x 0.375 in.(914 mm x 9.5 mm) W.T., Grade API 5L X 46 pipe filled with petroleum products having a specific gravity of 0.8438, and 2) a 40 in. O.D. x 0.344 in (1016 mm x 8.7 mm) W.T., Grade API 5L X 60 pipe filled with petroleum products having a specific gravity of 0.7301. These two pipelines were then each analyzed for unsupported span lengths varying from 100 feet to 400 feet (30.5 m to 121.9 m) under current velocities varying from 5 feet per second (fps) to 17.5 fps (1.5 to 5.3 mps). Actual length of the failed segment for each pipeline size was derived from survey data. Analysis of the computations of loads imposed upon the pipelines by the estimated current velocities, concurrent exposure of critical span lengths, the frequency of the loading and unloading, and the duration of these loadings indicate that failure of each pipeline was due to the fatigue of the metal caused by vortex shedding (flutter) of the current flowing over a round (pipeline) body. These results compared favorably with measurements of the failed pipelines by the National Transportation Safety Board (NTSB).

The U.S. Department of Transportation Office of Pipeline Safety (OPS) administers the pipeline safety regulations in the Code of Federal Regulations, specifically 49 CFR Part 192 for the natural gas industry and Part 195 for the petroleum industry. In response to the severity of leaks and collateral damages incurred on an aging infrastructure in recent years, the U.S. Department of Justice and OPS have enacted stricter regulatory enforcement and new integrity management programs for each industry. Industry response and compliance definition have been diverse: Part 195 defines a high-consequence area (HCA) to include commercially navigable waterways, high population areas, other populated areas and unusually environmentally sensitive areas; this places most of the northeastern United States in the HCA classification for petroleum pipelines. The natural gas industry, as regulated by Part 192, defines an HCA based on the area classification and the potential-impact radius of a worst-case incident. These differences have resulted in two distinct approaches to obtaining and maintaining compliance. In addition, total repair costs and permitting requirements vary widely across the United States, and the time necessary to acquire permits in the Northeast can easily exceed the 60-day or 180-day time limits under Part 195, with some agencies having no emergency permit process. To offset these critical issues, the integrity management program should incorporate the permitting lead times into the repair plans, and repair site access plans for equipment and materials should allow for requirements imposed by the permitting agencies as a condition of issuing the permit. This paper identifies environmental permitting requirements relative to pipeline facilities and describes key steps that can be taken to avoid compliance conflicts among regulatory agencies. Also, environmental permitting issues and requirements to minimize the impacts on pipeline repair plans that cause compliance conflicts with the pipeline safety regulations are discussed.

While there are many rehabilitation technologies available to reduce inflow and infiltration (I/I), identifying the best and most cost-effective strategy or combination of strategies can be a difficult task. A number of sewer rehabilitation projects using various rehabilitation methods are currently being monitored to evaluate the effectiveness of those technologies. The objective of this work is to quantify the effectiveness of the rehabilitation methods being used to better predict flow reductions and select rehabilitation methods for future projects.

Like many areas around the nation, this community has had to deal with deteriorating infrastructure issues, specifically sanitary sewer collection system components. This case study involves a small community located in central Pennsylvania, with a population of less than 15,000 people. During wet weather, flows at all of the municipal wastewater treatment systems would significantly increase. Infiltration/inflow (I/I) was causing problems in the older areas of the community. The state regulatory agency required a restriction on new taps (sewer) in one of the drainage areas due to hydraulic overloading at one of the wastewater treatment plants. Additional regulatory steps were imminent due to organic overloading at another wastewater treatment plant. Community leaders were serious about implementing a proactive approach to addressing infrastructure deficiencies, but funding such measures is the primary hurdle facing smaller communities throughout the country. In Pennsylvania an annual Wasteload Management Report or "Chapter 94" Report is required for each permitted wastewater treatment/conveyance/collection facility. Five-year projections for hydraulic and organic loadings at each treatment facility are necessary as part of the annual reports. One plant in the community was very close to a projected hydraulic overload condition. Additionally, there was a sanitary sewer overflow (SSO) pipe designed and constructed in a portion of the original collection/conveyance system. As a direct result of these conditions, a portion of the drainage area was subject to temporary tap restrictions and a Corrective Action Plan (CAP) was required by the PA Department of Environmental Protection. The Corrective Action Plan included tasks such as installing flow meters in the system and at the unpermitted bypass (at the SSO); conducting subsystem flow monitoring; conducting physical survey (i.e. flow isolation, manhole inspections, CCTV); performing building inspections and related repairs; smoke testing; internal and external mainline sewer/manhole repairs; lateral investigation/repairs; post-rehabilitation flow monitoring; and closing of the SSO. Due to the various problems facing the municipality, multi-faceted programs addressing the system's problems were initiated in 1999. Implementation of these various programs continues today throughout the community. This paper will discuss the tasks performed by the municipality over the past five years, lessons learned, unique approaches, and interim results of the program.

As the nation's sanitary sewer infrastructure continues to deteriorate, and as millions of miles of collector pipes and laterals continue to leak clean water which leads to sanitary sewer overflows, it becomes more and more important to quickly and cost-effectively determine these sources of leakage. There are a number of investigative methods that engineers, owners, and contractors have traditionally employed to determine sources of infiltration and inflow (I/I). These include smoke-testing, dye-testing, infiltration weiring, and basement inspections, just to name a few. These methods are labor-intensive and can be very costly. In addition, the methods have very specific application and, with the number of investigative methods available, it is difficult to select the appropriate method for a situation. But what if one could take flow meter data and use it to characterize the types of I/I entering the system? What if the investigative method could be chosen without having to go through a "trial-and-error process"? Malcolm Pirnie has developed a field-verified and repeatable procedure in which the sources of I/I can be determined by examining flow meter data collected during wet-weather events. This paper outlines those initial steps that are necessary to collect valid and true flow data, discusses how different sources of I/I are exhibited during wet-weather events, how these sources can be identified from flow meter data, and, how to determine the appropriate investigative method to use once the types of I/I sources have been determined. The paper also includes real-life examples and success stories that will be used to support the procedures.

This paper discusses the design and installation of a Grouted-In-Place PVC liner (GIPL) in a large diameter cast-in-place concrete pipe (CIPCP). The Sims Bayou trunk sewer in southeast Houston, Texas consists of several miles of 72 in. (1.83 m) and 78 in. (1.98 m) nominally circular concrete structures built about 40-years ago. This paper deals with the structural rehabilitation of approximately 1500 feet (457 m) of 72 in. (1.83 m) and 8500 feet (2,591 m) of 78 in. (1.98 m) of this sewer that has deteriorated due to hydrogen sulfide induced corrosion of the inner surfaces of the pipe walls. The design of the GIPL follows classical engineering mechanics for composite reinforced concrete structures. Design examples are given for various levels of deterioration of the host structure.

Usually the cost of sewerage rehabilitation is large but the budget is limited. Thus, a priority list for sewerage rehabilitation is necessary. This research is to establish an evaluation model to find out the cost-benefit ratio for each sewer sub-system. An evaluation model was established through an analytic hierarchy process (AHP). Initially, a comprehensive list of factors affecting the sewerage rehabilitation was established based on the result of a brainstorm meeting. Then, through an expert questionnaire, the weights for all affecting factors were estimated. Moreover, appropriate scoring rules, which convert qualitative factors into quantitative score, were set according to literatures, law and regulations, or personal experiences. By multiplying the all quantitative affecting factors and their weights, an overall score can be obtained for the cost-benefit evaluation. Finally, the authorities can set up the strategy for the sewerage rehabilitation by considering both the rehabilitation priority and budget limitation. This evaluation process was applied to a sewerage system in the 9^th re-planning district which was located in east Taichung city, Taiwan.

Due to financial constraints and lack of historically available rehabilitation methods, sewer lines in many US cities have decayed to a critical state, and may be considered unsound or severely compromised. Although there are a number of available methods that provide guidelines on assessment of the structural integrity of the rehabilitated sewer, they are incomplete and in need of improvement. The current paper presents aspects related to the theoretical background in the field, and how these theoretical developments influenced the most used methods and standards in the industry. It is then shown that, the rehabilitation industry, which has been historically dominated by cured-in-place liners, has only had limited needs for calculating the structural enhancement of the rehabilitated line. However, there are in existence very large main lines, sometimes round, but more often some sort of non-round profiles, that exhibit an advanced level of deterioration. Such lines do require the rehabilitation process to also restore, to a certain level, the structural integrity of the host pipe (structure). In such cases, the above mentioned methods, standards, as well as rehabilitation techniques pose significant shortcomings. For such projects Ameron International has specifically developed a new type of glass-fiber-reinforced resin (FRP) pipe. This new type of pipe is available in both round and non-round sections and can be designed to provide the capability for significant structural rehabilitation. The second part of this paper identifies necessary improvements required for a unified structural analysis standard that would cover all foreseeable rehabilitation projects. It is demonstrated that the magnitude and complexity of such a task require joint effort in the industry. Finally an outline of an extended analysis is presented, and future recommended actions are listed.

While a number of small to large older cities are undertaking repairs and maintenance, several other newer cities are planning for installing wastewater systems. Infiltration due to leaking pipes, manholes, laterals and other components of a wastewater system will add to the problem of overflow and over load the treatment facilities. Frequent overflows not only lead to regulatory problems but also increase the treatment cost. Leaking systems will result in the erosion of soils through the leaking joints leading to the settlement of the ground surface, formation of sinkholes and damage to surrounding pavements and structures. Literature review indicated that Standard ASTM pipe-joint tests varied with the type and size of pipes. In order to quantify the infiltration at various types of pipe-joints, a unified testing program was developed to test 30-in. diameter (76.2 mm) sewer pipe-joints up to a hydrostatic pressure of 50 kPa (7 psi). A testing protocol was developed and approved by a steering committee with representation from the USEPA, pipe associations, cities and consulting engineers. The testing protocol outlined the procedures to determine the leakage rates at pipe -joints under shear loading and angular deflection. A testing facility was designed and constructed in the CIGMAT Laboratory at the University of Houston. Pipe joints were tested in duplicate. Concrete pipe joint, PVC pipe joint, fiberglass pipe joint and clay pipe joint were tested. Relationships between shear strength at the pipe joint, deflection of the pipe and the angle of rotation of the pipes at the joint have been developed.

This paper presents a comparison between AWWA C303 Bar-Wrapped Concrete Cylinder Pipe and Mortar Lined and Mortar Coated Steel Pipe and shows the similarities in manufacture, design and installation between the two types. Also discussed is the fact that the Bar-Wrapped Concrete Cylinder Pipe is manufactured using similar equipment to that of the Steel Pipe for cylinder fabrication, mortar lining, steel joint rings and mortar coating. The two types are also designed similarly for both internal pressure and external loads. This paper will discuss the major differences between the two types and concludes that the Bar-Wrapped Concrete Cylinder Pipe can be easily classified as Steel Pipe.

This paper discusses the issues to be considered when designing a water transmission main, from project planning to commissioning. It is important to understand that coordination is essential and that design decisions made about one aspect of the project affect the design of the entire transmission main system. Transmission mains work as intended by the client and provide many years of service when they are properly designed, the materials are manufactured according to the standards, and the pipe and accessories are installed as intended. Although unanticipated situations may arise during construction and placing the main into service, the number of unforeseen construction obstacles can be minimized by careful planning. A detailed checklist can be developed by building upon the knowledge and experience gained on previous projects. This paper will present examples of unanticipated situations, how they were handled; and the consequences that became evident during construction, at commissioning, or after the transmission main had been placed in service. The benefit of a detailed checklist is savings in time and money for the client, the consultant, the contractor and the pipe supplier.

Concrete Pressure Pipe joints are restrained for thrust by welding or by using mechanical joint restraint devices. This paper presents the findings of a leak investigation conducted on a 48-inch (122 cm) Prestressed Concrete Cylinder Pipe utilizing the Snap Ring mechanical retrained joint system. In the summer of 2001 during field hydrostatic pipe testing of the Sandy Point Pump Station in College Station, Texas, several 48-inch (122 cm) pipe joints sprang leaks before achieving the specified test pressure. Preliminary investigation of the pipe showed that the Snap Ring joints leaked at a pressure less than the specified test pressure and less than the rated pressure capacity of the Snap Ring. A more thorough investigation then followed to determine the cause of the observed leaks. As a part of the investigation, two pipe joints were removed in a preserved condition and transported to the pipe manufacturer Hanson Pipe & Products plant in Grand Prairie, Texas for further evaluation. At the plant, the joints were subjected to hydrostatic pressure tests followed by a complete forensic evaluation. The investigation showed that the failure was due to the inappropriate field assembly and installation of the Snap Ring pipe joints.

In the case presented, the City of Dallas Water Utilities (DWU) had contracted the design and construction of approximately 30 miles (48 km) of a 108 inch (2,743mm) diameter Prestressed Concrete Cylinder Pipe (PCCP) raw water force main. Phase I, which consisted of 7 miles (11.3 km) of pipe, had failed a series of hydrostatic pressure tests when its test pressure was increased above 190 psi (13 bar). This suggested the presence of high pressure leakage. Attempts were made to locate the leaks utilizing both visual inspections (internal and external) and correlators. Neither of these methods proved effective. In a further attempt to locate the leaks, JD Stephens Contracting was hired by the bonding company to excavate and repair several areas of the pipeline. When the line continued to fail its pressure tests, Wiss, Janney, Elstner Associates, Inc. (WJE), the forensic engineers contracted to assist in the remediation of the pipeline, sought out a new method. In August 2004 WJE contracted with the Pressure Pipe Inspection Company (PPIC) to inspect Phase I of the Lake Fork Raw Water Transmission Main using a modified version of an in-line acoustic-based leak detection system known as Sahara. Sahara is normally used as a condition based asset management tool that identifies leaks in in-service pipelines of any construction type greater than 12" (300mm) in diameter. Deployment of the system into a pre-commissioned line therefore required a variety of operational and physical modifications. Once these modifications were completed, the inspection was initiated. Two leaks were successfully located. After the inspection was completed, the presence of the leaks was verified and the line was repaired. The rehabilitated line passed its hydrostatic test and was handed over to DWU.

The sizing of larger sanitary sewer trunk lines and interceptors has been a vague practice. Using a typical peaking factor applied to a serviced population at an average dry weather flow (e.g., 10 States Standards) has been the traditional approach. This approach (assuming well-designed, specified, and installed pipe) is acceptable for new collection systems; but what about aging systems? What happens when the existing collection system contributes high amounts of clean water, either in the form of inflow or rainfall-induced infiltration? As the nation's sanitary sewer infrastructure continues to deteriorate, and as the miles of collector pipes and laterals increasingly leak, leading to sanitary sewer overflows (especially in the form of backups in residential homes), the sizing of replacement and relief trunk lines and interceptors has become increasingly important. How do we adequately convey the wastewater flow during wet-weather events without undersizing or oversizing the relief interceptor or unnecessarily increasing construction costs? A procedure to size replacement interceptors using flow monitoring data collected on existing interceptors in response to wet weather events can provide the answers.

Recent years have brought increasing pressure from Federal and State Regulators for more comprehensive management of collection systems in an effort to significantly reduce releases of untreated sewage to the environment. This has created a need to understand what the flows in the collections systems are doing at all times and during each season. In turn, this has created an increase in reliance on flow monitoring to understand actual system performance and increase reliability in predicting future wet weather performance and bottlenecks. Numerous flow metering technologies are available; each with their own set of advantages and disadvantages. When due care is taken to implement flow monitoring studies, numerous benefits are realized including: 1) Determining all the flow components including average dry day flow, wastewater production, and Inflow & Infiltration (I/I); 2) quantifying areas of excessive I/I and verification of post rehabilitation I/I reduction; 3) Use of the flow data to generate powerful scattergraphs that "tell the complete story" about system capacity at each monitored location; 4) Improving operation and maintenance (O&M) through defensible wastewater billing, real-time surcharge detection and alarming; and 5) Reducing O&M and capital projects costs through the quantification of backwater caused by flow throttling.

One of the challenges faced in maintaining the aging sewer systems is the infiltration, which is caused by the deterioration of the sewer systems. In this study, A table top lateral joint model was used to investigate grout movement through soil, when sealing sewer pipe leaks at lateral joints by grouting. Acrylamide chemical grout was injected through a leaking lateral joint into a coarse sand (d₁₀=0.5 mm), using 3 psi (21 kPa). The volume of infiltration was measured before and after grouting to determine the effectiveness of grouting. The volume infiltration was measured at 1 min, 1 hr and 24 hrs. after grouting using an external water pressure up to 3 psi (21kPa). At the end of the test, the shape of the grout bulb around the joint was mapped. A mathematical model was developed to determine the shape of the grouted region around the lateral joint, and verified with the experimental data. The amount of grout used to control the leak around the joint was compared to the recommendation of ASTM F 2304.

Government Accounting Standards Series 34, often referred to as GASB 34 (Government Accounting Standards Board 1999) is an accounting standard implemented to better account for and manage assets where federal money is involved. Many people have chosen to use the modified approach to implement this accounting standard. The use of this modified approach to the standard is conditioned on the performance of at least one complete condition assessment and documentation that the eligible infrastructure assets are being preserved approximately at the condition level the government has established and disclosed. The choice of materials, linings, coatings and the use of corrosion protection on pipes all must be evaluated in the decision to use the modified approach of implementation of GASB 34. The differences in costs for varying combinations and the resultant life expectancy with their resultant effect on the accounting procedures will be presented. As conditions for buried pipelines vary considerably, the comparisons will be on relatively equal conditions. The results will identify a procedure to follow for different conditions. Maintenance must be planned, implemented and accounted for. This procedure will lend itself to an evaluation that can be used and will result in the best-cost decision for the expected life of the infrastructure asset.

Deterioration models allow asset managers to evaluate current conditions and to predict future conditions of infrastructure assets. The transition probabilities obtained from deterioration models can be used for Life Cycle Cost Analysis (LCCA) and for deterioration-based valuation. This paper describes the development of Markov chain-based deterioration model using the ordered probit model-based approach. The proposed model is applied and evaluated using the condition data of sewer pipes managed by the city of San Diego's Metropolitan Wastewater Department. Advantages and drawbacks of the model are discussed. The paper concludes that in order to gain greater accuracy in deterioration modeling, periodic assessment of the assets with more rigorous data types is desirable.

Zone 7 is a treated water wholesaler in California, providing service to approximately 190,000 customers in the cities of Livermore, Pleasanton and Dublin. Zone 7 facilities include two treatment plants and 32 miles (51.5 km) of transmission pipeline. The current maximum daily demand is 74.36 MGD (3258 l/s) delivered to 36 customer turn-outs ranging in maximum daily demand from 7 to 5,200 GPM (0.44 to 328 l/s). An Asset Management Study was conducted to assess future expenditures required to meet level-of-service requirements for water delivery. As part of this assessment, the vulnerability, or likelihood of failure, was estimated along with criticality, or consequence of failure. This analysis was designed to highlight transmission system elements that were most likely to cause level-of-service failures. WinPipes, an EPANET based water distribution system solver and output interpreter was used to evaluate the consequence to the level-of-service associated with pipe failure. The fraction of demand not met during a pipe break event was used as a measure of criticality of the pipe to the system performance. The simultaneous failure of two pipes was also evaluated to account for catastrophic earthquake induced failure. The results of the criticality analysis were used to prioritize future inspection, maintenance, and replacement tasks.

Paper addresses the behavior of polyvinyl chloride and ductile iron pipeline due to fault displacement by Discrete Element Method (DEM) and an estimation method of allowable fault displacement. In modeling of pipe and joint, nonlinear material properties and nonlinear joint characteristics (allowing detachment at joint) are considered. Under the set of various conditions with pipe material, pipe diameter, crossing location and crossing angle, the allowable fault displacement to reach failure of the pipe is numerically simulated. The results show that narrow angle between fault line and pipeline provides unsafe condition for pipe. Furthermore, a simplified formula to estimate allowable fault displacement is proposed considering joint failures due to axial forces. Estimates from the simplified formula agree with simulation results. Finally, measures of installing pipeline with high performance joint are considered and these behaviors are discussed.

An extensive Permanent Ground Deformation (PGD) study was conducted on a proposed natural gas pipeline to be located north of Sacramento, in Colusa and Butte Counties, California. The majority of the 30-inch (76.2-cm) diameter and 25 mile long buried steel pipe will be cut and cover construction; however several portions of the pipeline will be installed by horizontal directional drilling methods (HDD). The natural gas pipeline will traverse areas of two potential PGD hazards: faulting deformation and lateral spreading. The pipeline crosses the Willows fault, and an HDD portion of the pipeline will underlie the Sacramento River where a potential lateral spreading hazard exists. A detailed analysis was carried out to evaluate the magnitude of PGD and potential impacts to the pipeline associated with each of these potential PGD hazard sources. This paper addresses PDG associated with faulting. Two and three-dimensional numerical modeling of fault deformation using the finite difference computer program FLAC (Fast Lagrangian Analysis of Continua) are presented and discussed. FLAC was used to simulate the fault rupture mechanism considering a 3.3-foot (1-meter) reverse and 1.8-foot (0.55-meter) strike slip displacement across the fault at approximately 1600 feet (488-meter) below the ground surface. The model captured the resulting ground surface deformation patterns. The 3D FLAC results were used in detailed stress-strain evaluations of the pipeline response using another commercially available finite element computer program, ANSYS. Results compared favorably to the allowable limit states that have been established in the American Lifelines Alliance Guidelines for the Design of Buried Steel Pipe.

In this paper, a two dimensional finite element (FEM) and boundary integral Equation methods (BIEM) are applied to determine the uplift forces on half-buried submarine pipeline in a sandy seabed. The main assumptions are potential flow theory for water and linear elastic stress-strain for soil and Darcy's law for pore fluid flow. Dynamic pressures around the pipe and uplift forces were calculated based on BIEM and FEM. Also dynamic uplift forces on pipeline with variable burial depths were calculated. The results of the numerical approach are compared with some analytical formulation based on potential flow theory and experimental data, and it is shown good agreement with both analytical and experimental data. Then, the main parameters of this problem have been discussed in relation to uplift forces.

Sometimes urban growth cannot be met by existing sewer infrastructure. That was the case for San Diego's Otay Mesa region near the United States/Mexico International border. An update of the City and County of San Diego's Master Plan indicated that, while ultimate development might not occur until 2040 or later, available capacity in the Otay Valley Trunk Sewer serving the region would diminish by 2010 for the eastern portion of the mesa. No sewer service is available to accommodate growth on the west mesa, which restricts residential development in the midst of the San Diego region's housing shortage. To address needed growth, design and construction alternatives to meet updated sewage flow projections were developed following a complete dynamic hydraulic analysis. Upon selection of the best alignment, a phased design and construction plan to facilitate anticipated growth and development projects, while serving increasing flows from the region, was created. This analysis served as the basis for developing a sewer surcharge fee of about $1,800 per Equivalent Dwelling Unit (EDU) based on the actual number EDUs each development requires given the project's water fixture counts. Construction has already started on phased improvements for Otay Mesa. With this well-conceived plan for new infrastructure, the City deferred $28 million in upfront capital costs by building the project in phases based on established sewer flow thresholds. This strategy allows capital funds to be used for other priority needs within the City.

The City of San Diego, California's Miramar Water Treatment Plant (WTP) upgrade and expansion project is the City's largest water department capital improvements project. The Miramar WTP is located in one of the City's most prominent and politically astute communities, Scripps Ranch. The community has seen its share of major pipelines tear up its streets over the last several years, including regional aqueduct lines ranging from 54- to 96-inch (1350- to 2400-millimeter) in diameter to this project's recent installation of 36- to 108-inch (900- to 2700-millimeter) pipelines crossing through some of the community's most active areas. Recognizing the community's sensitivity to the project, the City actively approached all identified representative community groups to participate in a community advisory group (CAG) that would be in place throughout the design and construction of the project. Through the City's proactive approach, the CAG not only participated in construction sequencing, design and alignment decisions, and facility closure decisions, they took ownership in the project and supported the City when other community members raised issues. A well planned community involvement program achieved early buy-in and ownership from the community, avoiding costly delays from public outcry during construction.

The study focused on developing a Life Cycle Cost (LCC) model for operating and maintaining a wastewater sewer system. In this paper, the structure of a LCC model is outlined. The spreadsheet model was developed at the Center for Innovative Grouting Materials and Technology (CIGMAT) and is based on the population and average household occupancy. Essential components of a wastewater system have been identified and divided into sectors with housing, commercial, educational and recreational facilities. Life cycle cost includes treatment, transportation, maintenance and rehabilitation of a wastewater system to control infiltration over the life cycle period. The model can be used to compare different rehabilitation and maintenance scenarios and identify the most cost effective approach to rehabilitate and maintain a wastewater system. The model (LCC-CIGMAT) has been calibrated using published data on various wastewater systems. To demonstrate the performance of the LCC-CIGMAT model, a medium size city with a population of 260,000 was analyzed.

The need for a corrosion resistant barrier liner in Fiberglass Reinforced Polyester (FRP) Pipe used in water and waste water applications is often misunderstood. This can result in over specification and unnecessary expense for the end user. Different corrosion or chemical attack mechanisms exist for different chemical exposures and temperatures. The primary degradation mechanisms are defined by Arrhenius law for the rate of a chemical reaction and Fick's law for the rate of diffusion. This paper presents exposure test data and discusses how Arrhenius and Fick's law drive the rate and type of degradation in water, waste water and sewer applications.

With an aging underground infrastructure, ever-encroaching population areas and increasing economic pressures, the burden on the municipal agencies to efficiently prioritize and maintain the rapidly deteriorating underground utilities is increasing. Accurate forecasting of pipeline performance is essential for prioritizing and risk management of the underground infrastructure. The essential function of a pipeline asset management system is to consider the pipeline maintenance and improvement needs and to arrive at the program of optimal renewal, replacement, and maintenance. Hence, the development of a pipeline condition prediction model will be indispensable to the concerned authorities in prioritizing the care and renewal of pipelines, and in pipeline asset planning and management. This research developed an Artificial Neural Network (ANN) model for predicting the condition of sewer pipes based on the historic condition assessment data. The neural network model was trained and tested with acquired field data. The developed model is intended to aid in identifying the distressed segments of the overall sewer pipeline network using a set of known input values. These can then be directed toward assessing and prioritizing the maintenance measures needed to prevent accelerated future distress and eventual failure of sewer pipes.

El Paso Water Utilities (EPWU) operates over 2,200 miles (3,541 kms) of water transmission mains. One of EPWU's primary goals is water conservation. Consequently, it has implemented a water management strategy that emphasizes conservation, increased use of Rio Grande water, increased use of reclaimed water, desalination and condition based asset management. As the pipe within EPWU's water transmission system vary by size, material construction type, date of installation, operating performance and ease of access, no single condition assessment technique can be used to establish the integrity of each pipe in its entire system. As a result, EPWU has implemented a multi-faceted condition assessment program. It has used the Remote Field Eddy Current / Transformer Coupling (RFEC/TC) technique to establish the baseline condition of some of its Prestressed Concrete Cylinder Pipe (PCCP). It has used Acoustic Emission Testing (AET) to determine the level of active distress in other PCCP pipe. Further, it has used the Sahara water transmission main leak location system to validate the integrity of other pipeline assets. EPWU is one of the first utilities to implement such a comprehensive condition based asset management program. This paper describes its experience and details how EPWU is using the information gleaned from this program to re-establish the integrity of its pipelines, prioritize its capital expenditures and selectively rehabilitate individual pipe.

This paper describes the results of an experimental and numerical investigation of scouring under a pipe due to currents. Two kinds of experiments were carried out. (1) The experiments which are related to the scour process below single and multiple pipelines and main effective parameters on it. (2) The experiments include investigation of adding a spoiler to the crest of pipe section to increase self-burial potential of the pipelines. In the next section a mathematical model based on potential-flow theory was introduced for simulating the equilibrium scour hole formed by unidirectional flow underneath offshore pipelines. The model employs a finite-volume method to solve Laplace equation in terms of velocity potential in a Cartesian coordinate system. In this research, the influence of major parameters on scour caused by current has been investigated.

This paper describes the application of fiber optic sensors (FOS) to integrity assessment of pipelines. FOS provide a solution for monitoring time-dependent defects including internal corrosion, external corrosion, and stress corrosion cracking. They can also monitor pipe movement, pipe stress, and buckling strains due to slope instability, ground settling, and currents acting on exposed river and stream crossings. FOS are an ideal component of direct assessment protocols — improving safety while also significantly lowering costs. Both laboratory and field test data are presented to demonstrate the capability of FOS.

There is a common myth among industry professionals that consistently attributes adhesive or "glue-like" qualities to the resin used in cured in-place pipelining applications. It is believed that the resin actually bonds to the host pipe material and in effect, creates a seal between the cured-in-place pipe and the host pipe eliminating any points of infiltration into the collection system. Extensive testing has dispelled this myth entirely as well as raises awareness of the presence of grease and other contaminants that eliminate the possibility of a seal being created between the two components. The concern for adhesion is increased when linings are used to renew lateral pipes and sealing to the main pipe lining is required. Levels of adhesion are relevant to the service life of linings that are specifically designed to seal lateral pipe linings to main pipe linings. The industry will require methods for testing the connection between cured in-place lateral linings (CIPLL) and the main sewer pipe. Test methods must consider material composition, contaminants, preparation, and external hydrostatic forces. Lateral lining technology has progressed significantly over the last 15-years and this paper discusses those advancements.

In this study, three commercially available epoxy-based coatings were selected to determine the changes in bonding strengths to concrete with curing time. The CIGMAT CT-2 (modified ASTM D 4541) test was used to determine the bonding strengths of the coatings to dry and wet concrete surfaces. The tests were conducted over a period of two years. A total of 33 CIGMAT CT-2 tests (laboratory and in-situ tests) were performed on the three epoxy coatings. Five failure types were identified. Test results showed that although all of the coatings were epoxy based, the bonding strength of the coatings to the dry and wet concrete surfaces were different. Epoxy-A (pure epoxy) and Epoxy-B (glass fiber reinforced epoxy) had good bonding strength (>1.4 MPa, 200 psi) on both dry and wet concrete surfaces; Epoxy-C (cementitous based epoxy coating) had poor cohesive bonding strength (<0.7 MPa, 100 psi) between the topcoat (epoxy) and the base material. A 3-D FEM analysis was performed to determine the effects of coating modulus and thickness on the stress distribution in the coating, coating to concrete interface and concrete.

Reliability of a pipeline with distressed prestressed concrete cylinder pipe (PCCP) was assessed by structural analysis. The objective of the structural analysis was to evaluate serviceability and strength of the pipe, assuming loss of prestress in the core concrete due to wire fracture and corrosion. The study included analyses to evaluate the capacity of the pipe core to continue to resist internal pressure, external soil loads, and live loads through arch action, utilizing passive lateral soil pressure to provide support for strength and stability. Phased soil/structure interaction analyses and stability analyses were conducted to estimate probable overload factors (safety factors) present in the distressed pipe to resist internal and external loads. Overload factors were calculated at load levels corresponding to core cracking, cylinder yielding, and core crushing.

The Tarrant Regional Water District (TRWD) operates two, 120 km long, large diameter prestressed concrete cylinder pipelines in north central Texas to daily supply water to over 1.5 million people. Both pipelines have suffered from failures due to corrosion, hydrogen embrittlement or inadequate thrust restraint, with about 800 pipe segments damaged. A model was developed to determine remaining strength of the damaged pipe. About 100 pipe segments, most of which have been replaced, were found to be damaged enough that they could fail and about 250 more were found to be damaged enough that further deterioration would put them at risk of failure. To prioritize their replacement, the District will use a fuzzy risk model. TRWD is attempting to balance the high cost of mitigating all damaged pipes with the potential cost of consequential damages due to a failure by modeling the risk. This paper will discuss the path TRWD is taking to further its model development of risk management of the pipeline.

This paper discusses actual experiences with failures of ductile iron pipe (DIP). Included are evaluations of the causes of the failures, the impact of various soil environments on DIP, and the effectiveness of polyethylene encasement and the standard factory applied asphaltic coating as corrosion control methods. Corrosion control methods that would have prevented these failures are also discussed.

A corrosion investigation was made on 35.4 kilometers (km) (22 miles) of pipeline carrying reclaimed water after 32 years of service near Incline Village, California. The pipe was excavated in five locations and samples were cut from the pipeline for testing. Methods used in the investigation include soil resistivity analysis, laboratory soil analysis, ultrasonic thickness measurements and mechanical testing of steel samples removed from the pipeline, alkalinity and pH testing of cement mortar lining of pipe samples, and a closed circuit television (CCTV) inspection. The investigation concluded that the pipe damage was mostly due to third party construction. The steel met the material design requirements. High chlorides and sulfates led to corrosion of the exterior of the pipeline in some locations. This paper presents the findings and conclusions of the study.

A change in the flow rate in a full pipeline will cause a change in the pressure within that pipeline. These changes are given careful attention in the well-designed pipeline; however, in the past it has been difficult to accurately measure these transient pressures after the pipeline is constructed and placed in service. Transient pressures exceeding the structural strength of the pipeline will cause damage in the form of rupture or, as is more frequently the case, in the form of latent damage that results in failure at a later date. Advances in digital data processing systems have significantly improved our ability to continuously monitor and record even the very-short waterhammer event. These improvements have facilitated monitoring for transient pressures under a wide variety of circumstances. Early detection of damaging transient pressure events is now more practicable, thus permitting the reduction of damage to pipelines resulting from these events.

Transient analyses of pressure surges due to tripping of pumps in a cooling water system (CWS) are presented in this paper. The proposed CWS would consist of four circulating water pumps, a once-flow-through condenser, two closed cooling water heat exchangers, and an outfall. The numerical model was calibrated by adjusting head loss coefficients to match the four-pump normal operating condition. Model simulations indicated that the simultaneous tripping of four pumps would result in very large negative and positive pressures throughout the system. However, significantly higher pressures were generated downstream of the condenser by the tripping of two pumps during a four-pump operating scenario. To limit the development of excessive pressures and avoid column separations, combination air inlet and outlet valves were installed at the discharge header of the pumps and at the outlet water boxes of the condenser. With these valves installed, the computed extreme pressures were close to the operating steady state pressures.

In this paper, the effect of water hammer on asbestos cement pipelines was investigated in hydrostatic test. The test experienced with water compressor. Pressure with this machine increased from 0 to 8.0 bar in B-class and C-class of asbestos cement pipelines. All of the A.V (Air valves) opened to release air from pipelines. Also, the test was performed up to 13.5 bar. After that we increased pressure slowly and constant rate, we saw that our gage show pressure with 1 bar tolerances. This tolerance was because of water hammer effect. These phenomena induced pipelines rupture. For solving this problem, pressure was increased in special manner. In this manner, two water compressors applied in endpoints of pipeline, concurrently. Two water compressors startup in one time. We saw that if standard method is used for ACP test, pressure will increase with 1 bar tolerance until water compressor is in line. The water hammer effect was considerable for large pipes.

This research investigated the performance of a soil-based flowable fill as an alternative backfill for pipeline construction. The excavated natural silty sand from a trench was used as the major ingredient in the flowable fill. The study consisted of two phases. In phase I, laboratory experiments were conducted to develop optimum mix formula. Tests included physical properties, flowability, and strength. In phase II, field trial construction was conducted to verify the accuracy of laboratory results and evaluate the field performance of the material. Based on the research, for strength values ranging from 300 to 1,000 kPa, the cement-to-water and water-to-solid ratios were the two most important parameters controlling the engineering performance of the material. Laboratory and field observations provided strong evidence that the use of soil-based flowable fill can be a practical solution and promote optimum quality for pipeline construction.

The density of the backfill material around flexible water pipe is an important quality control measurement to ensure support for the pipeline. If the backfill material is not properly placed at the recommended density, then it could not only affect the long-term performance of the pipe, but also damage the infrastructure around it. Field tests were undertaken at different locations to determine the in-situ density of backfill extending 30 inches (762 mm) in diameter around a water pipeline. The field methods included Shelby tube sampling, direct push method and nuclear gage method. Repeatability of the test methods was also investigated. Using the direct push method, the spatial variation in density and moisture content of backfill material around the pipe were measured. Results from the in-situ tests were compared to the density specified in the design, based on laboratory compaction testing.

Engineers provide the best service to their clients by optimizing the cost of projects without affecting the quality or performance. Since buried pipe performance is the result of interaction of both the pipe and the surrounding soil embedment, projects involving buried pipes require careful decisions in selecting both the pipe and the backfill to provide owners with quality projects at appropriate costs. Design decisions on pipe and backfill can become even more important when difficult ground conditions are encountered. Increasing pipe strength or stiffness may appear to be an appropriate step to address this situation, but ignoring backfill and construction issues may mean that the overall reliability of the project is not increased, or that optimum cost is not achieved. This paper presents a case study of a significant fiberglass pipe installation in soft native soils. Evaluation of native materials, available pipe materials, and construction procedures led to a design decision to use pipe with a stiffness of 18 psi (124 kPa), along with a carefully monitored construction process. Topics discussed include native soil conditions, pipe specifications, and available backfill materials. The paper demonstrates a rational process by which engineers can evaluate the relative benefits of modifying backfill materials, pipe strength or stiffness, or construction practices to achieve the most economical results for a client. The project was completed successfully meeting both quality and performance requirements.

In service evaluation of internal hydrogen sulfide deterioration of a 14.5 km (9 mile) long sewage force main constructed of 152 cm (60-inch) prestressed concrete cylinder pipe (PCCP) was conducted using sonic/ultrasonic resonant frequency data. One of the causes of concrete waste water pipe deterioration and failure is the thinning and weakening of concrete due to hydrogen sulfide generation at the high points of the line. In May 2003, it was reported that a large piece of sheet steel had been discovered on a bar screen at the wastewater treatment plant supplied by the 152 cm (60-inch) PCCP sewage force main. It was the second time in six months sheet steel had been recovered at the treatment facility. A current manufacturer of PCCP inspected the recovered piece of steel and confirmed that it appeared to be part of the steel cylinder from a large diameter PCCP. It was also reported that a large quantity of concrete and aggregate was being recovered at the sewage treatment plant and the upstream pump stations. The implications of the discovery of the sheet steel at the treatment facility are that the interior concrete core of the pipeline has completely deteriorated in places and the steel cylinder of one or more pieces of PCCP has corroded and dislodged from the pipe. It was probable that the deterioration of the pipeline was caused by hydrogen sulfide corrosion and that the pieces of steel cylinder came from the 152 cm (60-inch) PCCP sewage force main. Non-destructive stress wave measurements in the sonic/ultrasonic frequency range were made on the exterior of the pipe at excavated locations. The sonic/ultrasonic data is a direct measurement of the transmission velocity of both the compression and shear waves and the reflected phases of the compression wave from the inside face of the pipe. The transmission velocity values determine the elastic deformational characteristics of the concrete, including Young's, shear, and bulk moduli, Poisson's Ratio, and calculated strength values. The reflected signals resonate at a frequency that is related to the thickness and compression wave velocity of the concrete liner. Since the longitudinal velocity is measured directly and average thickness of the pipes are known, the average strength of the concrete pipe core as well as the presence of delaminations, spalls or pipe thinning can be determined from the measured resonant frequency. Structural analysis of the 152 cm (60-inch) PCCP was performed to determine the impact of pipe wall thickness reduction through hydrogen sulfide attack. This case study provides a summary of the non-destructive testing performed and the results of structural analysis of the 152 cm (60-inch) PCCP sewage force main.

No single method for monitoring Pre-stressed Concrete Cylinder Pipes (PCCP) using either standard corrosion monitoring systems or non-destructive techniques can accurately determine the onset of corrosion. This paper investigates the capability of the Inductive Scan Imaging Technique as a new single non-destructive tool in identifying and visualising corrosion of pre-stressed wires embedded in concrete and distinguishing between corrosion of varying severity, position and size. The future application and use of the new technique in determining the effect of cathodic protection (CP) on the performance of passivated, corroded and split pre-stressed wire is also discussed. The paper also discusses the advantages and limitations of the various available conventional monitoring techniques such as Static, Close Interval Potential Survey and polarization coupons to measure corrosion rates and non-destructive inspection methods that can identify distressed pipe areas.

Denver Water's Conduit No. 94 consists of 183 cm (72inch) and 168 cm (66-inch) diameter prestressed concrete embedded cylinder pressure pipe (PCCP). The PCCP conduit extends from the Moffat Treatment Plant located in Lakewood, Colorado a distance of approximately 17.5 km (10.9 miles) to 56^th Avenue and Washington Street in Adams County. Since its installation, the line experienced one catastrophic failure. In order to mitigate the risk of further breaks, condition assessment of the pipeline was conducted using conventional internal visual and sounding inspection to detect pipe in a state of incipient failure as well as non-destructive electromagnetic testing to determine the presence and quantity of broken prestress wires on pipes that showed no internal signs of distress. Electromagnetic non-destructive testing using eddy current/transformer coupling devices was performed on the Conduit No. 94 pipeline twice within four years. Estimates of the number of broken wires on individual pipes ranged from zero to several hundred. In addition to structural analysis of the impact of broken prestress wires on serviceability, pipes were salvaged from the pipeline for destructive testing to determine the accuracy of the electromagnetic test results. After each round of electromagnetic testing, pipes were salvaged and dissected to correlate the actual number of wire breaks with the number predicted by the non-destructive testing. Correlations between the actual number of wire breaks from the Conduit No. 94 pipe dissections and the number of wire breaks predicted by the non-destructive testing indicate that the electromagnetic testing is generally accurate in determining the axial location of broken wires on PCCP, but that quantification of the wire breaks is less precise.

This paper is intended to explore the physical and environmental aspects, relative to pipeline environments, of the reinforcing fibers and matrix resins used in the production of FRP Materials. With the imminent release of "PCC 2, Article 4.2 NON-METALIC REPAIR SYSTEMS FOR PIPELINES AND PIPE WORK; HIGH RISK APPLICATIONS" (ASME Article 4.2 Draft) many questions are asked regarding the FRP materials being specified and their appropriate uses. Various fibers, namely Carbon fiber, Glass fiber and Aramid fiber will be discussed as well as the form, woven, stitched and unidirectional, into which the fibers can be manufactured. The matrix resin chosen for use in various pipeline applications depends on environmental conditions. What environment conditions effect the choice of matrix resins? How do you as an owner evaluate the choices you are presented? Engineered materials present great opportunities to expand the options the pipeline industry is using to preserve its infrastructure. Making the correct choices regarding FRP materials requires the knowledge of what FRP materials can and cannot do for you.

Large-diameter pipeline inspection can be a costly and difficult undertaking and, as such, is often overlooked. These inspections are increasing necessary as the nation's infrastructure continues to age and deteriorate. Pipe failures in these large-diameter pipes are usually catastropic. The failure is typically sudden and unexpected and often involves major construction. As a proactive measure, a utility in the mid-Atlantic became concerned that some of their major interceptors were reaching the end of their design lives and required inspection. These interceptors are subject to significant sulfide attack during the warmer summer months. In addition, these interceptors lie beneath a major four-lane thoroughfare. The utility wanted to determine the existing structural condition of these interceptors, examine constructability issues, and decide if they should rehabilitate the existing interceptors or if they should replace the existing interceptors. This decision would be based on the findings of the structural assessment and constructability. This paper examines the approach in determining the structural condition of large diameter interceptors (20" to 66") with difficult access. Traditional cleaning and inline closed-circuit televising (CCTV) would be difficult and extremely costly. Therefore, zoom camera technology was selected. Zoom camera technology normally consists of an ultra high-powered zoom lens camera for rapid inventory and screening of collection system deficiencies.

A number of water utilities have successfully used Acoustic Emission Testing (AET) to locate active distress in Prestressed Concrete Cylinder Pipe (PCCP). However, in conducting an AET monitoring program, questions often arise as to: the maximum spacing allowed between units; the minimum duration of the monitoring period; and the system's ability to distinguish between wire breaks and wire slips. These questions determine the value of AET in a condition-based asset management program. To address these questions, scientific and fact-based studies were conducted. This paper discusses these studies using extensive analysis of AET field results. It suggests how water utilities can conduct AET programs more cost-effectively through knowledge of the maximum spacing interval for acoustic sensors and the minimum monitoring time required for pipes in different stages of distress.

A design engineer's primary objective is to solve problems. Often a problem will have multiple solutions that need to be studied to determine the best answer. The required calculations may be complicated and/or redundant. In such cases, spreadsheets can be used to analyze multiple solutions efficiently and accurately, and to produce graphs that convey the solution to the client. Typically, water transmission projects consist of transmission pipelines and pump stations. The hydraulic models generated for the projects vary in complexity from simple hydraulic grade line calculations to rating curves and system and pump curves demonstrating the effects of numerous variables. Spreadsheet software is readily available and can be used for many applications, including hydraulic grade line calculations and graphing, system curve calculations and graphing, rating curve calculations and graphing, life cycle cost calculations, pump selection, multiple solution optimization, and appurtenance design calculations. Spreadsheets can be applied in situations where hydraulic modeling software cannot, including some life cycle cost analyses, development of system curves where a mix of gravity flow and pumped flow must be considered, comparison of multiple pump and driver speed combinations, and open channel flow in a pipeline within a transmission system. When using spreadsheets for hydraulic modeling, the equations used can be located and checked, and the variables are accessible and can easily be manipulated. The data, calculations, and exhibits can all be organized according to the user's preference, and graphs and tables can be customized to meet the client's needs. Most importantly, using a user-generated spreadsheet for hydraulic modeling requires the user to understand the system and what is happening hydraulically.

Colorado Springs Utilities (Utility) provides water service to a rapidly growing population of 400,000. The Utility also owns and operates the Green Mountain Falls (GMF) water system located several miles outside of city limits. The GMF water system, serving 937 customers, is a separate water system consisting of small diameter cast iron and ductile iron water pipes. A significant portion of pipes are of unknown material. Fire flow was not considered when most of the system was constructed; therefore the initial model results show hydrant discharge capacities as low as 140 GPM (8.8 l/s). The first step to upgrade the existing system is the development of an accurate water model. User demand is predicted from billing records. Pipe roughness is estimated using a genetic algorithm-based optimization procedure. This paper discusses the modifications to the optimizer to facilitate the inverse model solution, the parameter estimation problem, and presents the results of the modeling and calibration of the GMF water system.

Traditional water system master planning procedures have included designing water distribution networks to meet minimum system pressures, velocities and fire flow requirements. With the population of Colorado Springs projected to increase to nearly 520,000 by 2030, the Colorado Springs Utilities (Utility) has adopted "design-by-optimization" to reduce costs and streamline design procedures. WinPipes is an EPANET-based water distribution system solver, optimizer, and output interpreter. It was modified for the specific requirements of the Utility. The optimization program was designed to evaluate multiple performance criteria for maximum and minimum pressure, maximum velocity, flow from a single hydrant, simultaneous flow from multiple hydrants, pump capacity and energy, and component failure based reliability. Development of the optimizer as well as the design-by-optimization approach of both a small and a large development is presented. The master planning of these developments represented unique challenges for the design and operation of the Utilities distribution system. Design-by-optimization allowed the Utility to meet specific design criteria at near minimum cost without compromising the integrity or reliability of the distribution system.

Interceptor sewers, with diameters generally greater than 1.5 meters (5 feet), traverse long distances from their terminating sewage treatment plants as well as cross varied geologic materials and numerous physical features. Routing of portions of pipelines often positions their alignments in lowlands, flood plains which typically contain unconsolidated alluvial deposits, and adjacent to watercourses to minimize impacts on existing improvements. Invert grades can be deep when compared to other utility grades and at times pipelines must be located within local groundwater aquifers. Pipeline dewatering involving deep wells and wide excavations can induce settlement of soft and loose subsurface soils which results in potential surface settlement and distress to existing improvements within the radius of influence of dewatering drawdown. This paper presents the methodologies used for predicting the surface settlement for portions of the Lower Northwest Interceptor (LNWI) project to be constructed in West Sacramento, California. The LNWI project consists of five sections of large diameter (1.4 to 3 meters) interceptor pipes (comprised of four force main segments and one gravity sewer segment), fourteen tunneled crossings, and two pump stations. The total length of the LNWI project is approximately 31 kilometers (19 miles). The LNWI crosses numerous major streets, highways, railroad embankments and a Barge Canal. A Standard Penetration, Dilatometer and Cone Penetration Test exploration program, used to obtain constrained moduli, consolidation characteristics and soil types, permitted an assessment of potential settlements. Modeled drawdown profiles in three dimensions allowed to estimate the affected soil volumes and associated loading stresses due to dewatering. Predicted magnitudes of settlement along and laterally out from the excavation alignments are also presented.

In this study, load-deflection relationship for flexible pipe in trench condition was investigated. A soil box test was performed to investigate the behavior of flexible pipe with flowable backfill. Test was conducted using an 200 mm (8 inch) diameter flexible pipe in a trench condition, 2.25 times the diameter of the pipe. Flowable fill with unconfined compressive strength of about 75 psi (28 days) was used as backfill. After a day of curing, a maximum surface vertical stress of 770 kPa (112 psi) was applied. The pipe deflection, in-situ soil stresses, and strains in the pipe walls were measured during backfilling, and surface loading during the two months of testing. The vertical deflection in the pipe with flowable backfill during installation was — 0.03 % (extension) whereas after applying a surface loading of 770 kPa (112 psi) it was 1.0 % (shortening). The elastic modulus of backfill, Poisson's ratio of backfill, axial stiffness of pipe, interface friction angle between backfill and soil box and soil box width were important parameters in predicting the pipe deflection and stresses in the pipe using the finite element method.

Most thermoplastic pipes exhibit peaking behavior during the initial backfilling process. It is shown with the actual field data that the peaking deflections can be beneficial for minimizing the long-term deflections of the pipe. An approach similar to the one proposed by Spangler is used to derive a formula for estimating the peaking deflections of thermoplastic pipe due to forces generated during the initial backfilling. The formula is tested in light of a number of field installation cases. The results show that the proposed formula predicts peaking deflections of both PVC and HDPE pipes accurately under a variety of backfilled conditions.

The analysis of longitudinal deformations compared to performance limits of deformation in buried pipes is referred to as longitudinal mechanics. Principal causes of longitudinal stress and strain within a pipe system include changes in temperature, internal pressure or vacuum, and beam bending. The widespread use of thermoplastic pipes, namely polyvinyl chloride (PVC), in municipal applications throughout North America in the past four decades has made it necessary to re-visit the topic of longitudinal mechanics for pipes that incorporate various types of joining systems. Typical North American PVC pipe joints are either bell-and-spigot gasket-joint or welded (heat-fused Fusible PVC and solvent-cement joints). Analysis herein focuses on the three main causes of longitudinal stresses and strains in bell-and-spigot gasket joints and welded joints, and includes discussion of theoretical concepts such as the Poisson effect and the Reissner effect. Topics which have raised issues in the field such as ponding due to sags in a PVC gravity line and the occasional cracking of PVC pipe bells during or after installation are also discussed. Current industry and manufacturer recommendations of various design parameters are provided in conjunction with the analysis.

The major factors affecting the short term and long-term performance of plastics in engineering applications include a) chemical makeup, molecular architecture, and additives; b) raw material and component manufacturing processing parameters, and c) installation and service conditions that include load, loading rate, temperature and other environmental conditions. The successful design of plastic components for an intended application requires an understanding of the role of the above factors together with economic considerations that account for the cost of fabrication as well as for the cost of failure. Material characterization and ranking with respect to strength, toughness and durability provide a basis for rational design with plastics. There are industrial standards and regulations developed to assist in product qualification. Advantages and limitations of existing standards and methods for lifetime prediction of engineering thermoplastics, as well as the recently proposed specification for predicting a 100-year service life of high density polyethylene (HDPE) drain pipe will be discussed. Extrapolation of relatively short-term (1 – 1.5 years) test data into a 100-year service life is a challenging task. Purely empirical correlations leave the currently proposed extrapolation highly uncertain. A detailed understanding of the potential failure mechanisms and knowledge of fundamental physics of accelerating test conditions are necessary to build confidence in such an extrapolation technique.

Plastic pipes used in gas utility distribution lines have relatively small diameters and they are buried at relatively shallow depths, usually less than one meter below the ground surface. All existing methods used for estimating plastic pipe deformations are approximate and not well suited for small diameter piping. Applicability of ring-deflection theory in determining plastic pipe deformations was investigated. Laboratory tests were performed to monitor the deformation of high density polyethylene pipes during burial. Diameter changes of the pipes during burial in sand box were monitored using an instrumentation cage. Pipe diameter changes from ring-deflection theory and diameter changes measured during the laboratory tests are presented.