Pipelines 2001: Advances in Pipelines Engineering and Construction

The design of buried flexible pipe involves checking for load-induced deflection, buckling strength, strain or stress under internal pressure, strain or stress from combined loading, and handling stiffness. Most of these design checks involve using the design parameter commonly referred to as the modulus of soil reaction, E'. Despite the fact that modified Spangler's equation has been around for over several decades few engineers in practice even know how this E' is defined let alone how to obtain a proper value for it. The most popular form for E' comes from the empirical data published by the U.S. Bureau of Reclamation and most consensus standards carry these values despite its numerous shortcomings. The irony is that the U.S. Bureau of Reclamation knew that their data were providing values of E' varying several hundred percent from a mean value, yet, never even considered other factors that would be significant in explaining their unreliable E' values. Its pure simplicity of the U.S. Bureau of Reclamation values led to them being in use in the hands of the pipe supplier and never its engineering soundness. The purpose of this paper is to start from the fundamental pipe-soil interaction principles and geotechnical engineering and build the engineering know how needed to establish E' values on a project-specific basis allowing for most significant factors. A step-by-step methodology is presented.

Thermoplastic pipe has become popular for storm water sewers and culverts because of its light weight and low cost. Profiled pipe is often used because it provides higher stiffness with less material. There are no standardized profiles for these pipes and a wide variety of wall geometries have been developed. The geometries of the profiles may induce some localized deformations that can influence their structural performance. The effects are investigated for a range of commonly used pipe profiles. Axisymmetric finite element analysis is used to investigate the pipe behavior under axisymmetric loading. The local wall geometry of the pipes is explicitly modeled in the analysis.

Structural behavior of buried pipes is not strictly elastic, especially at performance limits. Except for hoop stress caused by internal pressure, analysis should be pipe-soil interaction based on non-elastic properties of both pipe and soil. Elastic theories are only approximations, and may be misleading. At performance limit (beyond elastic limit), flexible pipes are ductile and plastic. Rigid pipes may be brittle. Granular soil is particulate. Basic principles of statics and mechanics of materials provide a rational procedure for non-elastic design and analysis.

This work first discusses a typical stress distribution of a finite element analysis of a buried pipe under an impact load on the ground surface. It then focuses on a recent analytical solution and its application to a sample problem: a pressurized concrete pipe buried underground, subjected to a uniformly distributed load ranging from 0.496 psi. to 19.84 psi. Its inside and outside radii are 4 in. and 4 ½ in., respectively. It has an internal pressure of 300 psi. and a depth of 7 ft. below the surface. With an approximate Young's modulus of 3 x 10⁶ psi. for the concrete pipe, 200 psi. for the soil, and a range of assumed soil Poisson's ratios, the resulting hoop stress behaves in a dramatic manner which agrees well with a finite element analysis. The capability of the solution to provide intensities of the stresses at the precise inside surface suggests that it can be a useful design tool.

Deflection tests, under 120° sand-bearing loading, were conducted on 914-mm and 1372-mm diameter cement-mortar lined and coated welded steel pipe (WSP) at Ameron's Engineering Experimental Center at South Gate, CA. WSP with two types of mortar-coating reinforcement were tested. The test set up and test pipe were instrumented with load and deflection measuring devices, which were connected to a data logger for direct read out and data storage. The mortar linings and coatings of the test pipe were observed for the cracking patterns during testing to establish the limiting deflections at different structural events. The test pipe design, test set up, and test procedure are described. Test results are discussed and conclusions are given.

Buried pipes with shallow depth of cover have a risk of flotation caused by buoyancy of groundwater. To clarify this behavior of buried pipes, the results of laboratory model tests with several prevention works were evaluated by numerical analyses using the distinct element method (DEM). For several uplift prevention works, it was found that the numerical analyses could express different results qualitatively. Especially, prevention work using geogrid and gravel over the pipe were effective against uplifting in the experiment, and DEM analysis also indicated a similar result. These results suggest that the DEM simulation models could help to estimate the limit cover of buried pipes for designing.

Effective early planning is a key step in successful implementation of pipeline projects. Planning activities are often used to support permitting, financing, stakeholder acceptance, design and construction. One of the most important planning aspects of a pipeline project is the selection of an implementable pipeline route. Many resources are available to help evaluate the various factors influencing pipeline route selection. In this paper, a versatile route selection procedure is presented that provides an analysis tool to help organize and evaluate the many influencing factors and resources available to the planning team. The procedure is adaptable to projects ranging from simple to highly complex. It allows for either a specific cost-based analysis or a less specific relative cost approach and is adaptable for calibration to historic site-specific cost data, if applicable. The procedure also provides a method to incorporate the cost analysis with non-cost issues. Route analysis by a quantitative scoring system or by more subjective evaluations are accommodated. Methodologies for stakeholder's to influence the character and results of evaluations are presented. The route selection process has been used successfully on a variety of both sanitary sewer and water system pipelines through the western United States.

The Greenville Water System (GWS) supplies drinking water to more than 350,000 people in four counties of upstate South Carolina through approximately 135,000 metered accounts. Water from two surface water treatment plants is conveyed to users in several large diameter transmission mains — the largest being a 72-inch prestressed concrete cylinder pipe (PCCP) that stretches 24 miles across Pickens County into Greenville. The 72-inch pipeline is an integral part of the GWS's water system and necessary to sustain daily water demand. Since 1997, this transmission main has failed on 3 separate occasions. These recent failures have prompted the GWS to accelerate the long-term plans that include the design and construction of a new transmission main parallel to the existing 72-inch main. In the year 2040, it is projected that a second large diameter transmission main would be needed to convey water from the Adkins WTP.

The Tampa Bay Region of Florida's West Coast has suffered increasingly in recent years from a shortage of potable water. Tampa Bay Water, the regional wholesale water supplier, has embarked on a $609 million Master Water Plan to furnish 4.85 m³/s (111 mgd) of potable water from new, environmentally friendly sources. A key component of the Master Water Plan is the North-Central Hillsborough Intertie. This 19 km (12 mi) long, 2150 mm (84 in) diameter transmission main is now under construction and will convey finished water into the regional transmission system from new treatment facilities. This paper addresses the challenges engineers had to overcome during the fast-track design of this important pipeline, which is being installed in a combination of urban and environmentally sensitive areas adjacent to the City of Tampa. Much of the route of the transmission main is located in the Tampa Bypass Canal corridor, a flood control facility. Other portions of the route cross areas containing wetlands and endangered species of fauna. Several archaeological sites were encountered near the location where the pipeline will cross the Hillsborough River. In addition, the transmission main is routed adjacent to local airport runways. The project includes 13 tunnels, and a 122 m (400 ft) long elevated crossing of the Tampa Bypass Canal. About 90 percent of the pipeline will be installed in easements. The timely acquisition of permits and property rights to construct this pipeline was critical. Completion of the $50 million North-Central Hillsborough Intertie in 2001 will help assure environmental stewardship through sustainable new water supplies for over two million residents in the Tampa Bay Area.

The proper design and construction of thermoplastic and thermosetting resin slipliner pipe requires a thorough understanding of material limitations. Proper calculation procedures must be utilized when determinant the annulus stresses developed during the grouting operation. Due to various inherent characteristics of each of the plastics, it is necessary that viable installation specifications be written and adhered to, and vigorous construction inspection be carried out in order to attain desired project life. It is usually recommended to grout the annulus for pipelines when utilizing a slipliner pipe. The subject of this paper is currently being addressed by the ASCE Task Committee on "Design Guidelines" under the Pipeline Infrastructure Committee. This paper does not necessarily represent a consensus of committee opinion on the subject.

The basic mechanisms of restrained hydrostatic buckling of nominally close-fitting, circular sewer liners are described, and the origins and limitations of current design formulae based on simple linear ring bending theory are explained. A fully consistent, non-linear theory, already the subject of several years of academic research in Europe and North America, is introduced as the basis of a new, practical approach for dimensioning liner pipe. Simple design charts and algebraic formulae are developed to reflect the important influence on buckling pressure of liner ring compressive strains and separately identified "characteristic" (i.e. renovation technique related) and "system" (host pipe related) imperfections. It is shown how the incorporation of these features enables the new theory to be applied with much greater confidence to a wider range of renovation techniques and liner pipe dimension ratios, and to provide the basis for better targeted product characterisation and proving tests. The predictions of old and new design theories are compared, circumstances in which there is significant divergence identified, and the extent of experimental justification of the new approach in such cases briefly reviewed.

This paper addresses appropriate analytical models for both flexible and rigid liner designs for the fully deteriorated pipe condition. The results of tests conducted in the Buried Structures Laboratory at Utah State University on one flexible and one rigid liner in cracked concrete pipes are reviewed and are shown to support the analytical models developed. Also, two little known (in the USA) reports on tests conducted in the UK in the early 1980s are reviewed and used to illuminate the technical issues under discussion. Unresolved issues are highlighted and the need for well-conceived and controlled experimental research is discussed.

Leakage testing of pipelines frequently is performed at the pipe manufacturing facility and again after the pipeline has been installed and backfilled. This paper discusses the formulas in various standards used to compute allowable leakage in pressure pipelines, the techniques commonly used for leakage testing, and problems that can be encountered. Pipe materials discussed in the paper include low-head concrete pipe, high-head concrete pipe, steel pipe with rubber-gasket joints, steel pipe with welded joints, ductile iron pipe, polyvinyl chloride (PVC) pipe, and high-density polyethylene (HDPE) pipe.

The design of thrust blocks for water pipelines and sewer force mains vary from one pipe material or standard to another just like the design of pipe wall thickness. This creates tremendous confusion among consulting engineers and owners of projects. The designers and the owners have to look up Design Manual M9 for concrete pipe, Design Manual M11 for welded steel pipe, Design Manual M41 for ductile iron pipe, and Design Manual M45 for fiberglass pipe. The marketing philosophy of the pipe vendors is that the more that these design manuals are in print the more confusion they create that the pipeline asset owners and the designers have to turn to the pipe suppliers for the design and development of the specifications. This results in an undesirable situation where the pipe manufacturers are designing and writing specifications they know they will have to meet when the projects are bid on behalf of the public. In other countries most water pipeline materials are required to meet a common standard, where design equations are kept the same while material properties vary from one pipe material to another. The purpose of this paper is to start from the fundamental principles of fluid mechanics and geotechnical engineering and build the engineering know-how needed to apply the same design methodology for all pipe materials and applications. A step-by-step design methodology is presented.

A series of tests for buried pipelines were performed to investigate the effectiveness of geogrids in enhancing the float up resistance of buried pipes due to buoyancy. The experiments were conducted using 1100-mm diameter pipes in a model sand ground. In the experiments four types of pipe floatation prevention methods were installed around a buried pipe with a shallow depth of cover. The prevention method consisting of a geogrid and gravel backfill material employed to increase the float up resistance of buried pipes. For shallow depths of soil cover the incorporation of geogrid reinforcement can lead to a decrease in cover to extremely shallow depth. The geogrid reinforced tests show that the forces preventing pipe floatation are contributed to by the dead weight of the overlying soil as well as bending mode deformation of the reinforced layers surrounding the pipe.

As part of the City of San Diego Water Utilities Capital Improvements Program, extensive research was conducted to evaluate the advantages and disadvantages of Controlled Low Strength Material (CLSM) and to prepare a recommend guideline specification for pipeline trench backfill. Numerous CLSM case histories were reviewed with respect to performance, economics, and implications to design, construction, and schedule. Manufacturers, suppliers and owners were contacted for their views on CLSM. Advantages of CLSM are well documented in the literature, and a modified version of the advantages of CLSM is presented. In addition, the disadvantages of CLSM are presented, providing a balanced treatise on the use of CLSM for pipeline backfill or other major civil works. Case histories, agency practices, and CLSM specifications from various agencies are presented. Quality control and testing and construction management issues are presented, along with a guideline specification and an extensive bibliography, providing a comprehensive synthesis of the state of the practice of CLSM.

This paper discusses pipeline design for the Sicangu Mni Wiconi Rural Water System (also called the Rosebud Sioux Rural Water System or RSRWS). This system, is part of the larger Mni Wiconi Project that serves 10 counties in south-central South Dakota.

The City of Houston, Texas is the fourth largest city in the United States. Over the last two years, the Gulf Coast area, and much of Texas, has experienced record high water demands due to the historical high temperatures, less than normal rainfall and economic development. These factors have required the City to pump high volumes of surface and groundwater to meet these record water demands.

The occurrence of the "Engineers Estimate" far exceeding the submitted contractors bids, or worse ending up considerably less than those submitted, creates client/consultant tensions. In many instances these estimates are based on historical cost tables which are then factored up or down by a regional index to produce a unit cost for pipeline construction. This method becomes difficult to defend when the owner wants to know why the estimate was either too high or too low. Working jointly with the Sacramento Regional County Sanitation District (SRCSD) a costing model based on estimates of contractor production was developed to determine base construction costs for the $1,000,000,000 SRCSD Interceptor System Master Plan 2000 Capital Improvement Program. The costing model includes variables for labor, materials, and equipment. By inputting estimates for production rates, which vary based on soil type, type of development, depth of installation, method of construction, etc., the model calculates unit costs for pipeline construction. Although this does not guarantee flawless estimating for cost of construction, the basis for these costs are tied to specific assumptions, existing conditions, and anticipated contractor performance which may be easily explained and defended.

Experience has shown that a high soil density will ensure high soil stiffness. In selecting a backfill material the designer will consider such things as depth of cover, depth of water table, pipe materials, compaction methods available and so forth. While the understandings of stresses in a pipe from other sources are satisfactory, the stress due to the installation conditions is not clear. It is attempted in this paper to further advance the understanding of the stresses and deflections in pipes due to installation process.

This paper presents a selection of design temperatures for thermal loads in buried plastic piping. Gas companies often assume that the CFR requirement for design of mechanical couplings for an instantaneous change in temperature of ΔT = 55°C applies to all aspects of the PE system. This assumption leads to very conservative designs, and does not represent the range of temperature changes due to pipe installation and seasonal temperature variations in the ground. This paper presents data from measured ground temperatures in the northeastern United States to develop seasonal design temperature ranges. Measurements of PE pipe temperature when exposed to direct sunlight then inserted into cast iron piping are used to assess temperature changes that might occur during pipe installation. Design scenarios are identified that represent reasonable situations for the range of temperatures PE piping would be subject to, and stresses are evaluated for these conditions. Stress superposition methods are used to develop design charts for evaluating thermal loads.

An underground, double-contained high-density polyethylene (HDPE) pipeline was required to transport extracted groundwater along a 1-mile (1.6 km) route through a residential neighborhood to a treatment system. The goal of design was to choose a pipeline system that was both reliable and practical, and that could operate under a broad range of conditions. The selected pipeline assembly, which consisted of a 12-inch (300 mm) carrier pipe within an 18-inch (450 mm) containment pipe, included an internal leak detection system. The design process emphasized identifying appropriate pipe materials and developing specialized details to reduce the potential for leaks along the pipeline. Other design activities included evaluating systems to detect and locate leaks and addressing material-specific construction issues. Installation of the pipeline system presented unique challenges that required the combined efforts of the engineers, contractor, and suppliers. These challenges included fabricating and installing custom-made double-containment termination and drain fittings, as well as pressure testing the system using air, water, and helium.

A study has been performed on the seismic analysis of jointed pipes systems in which the multi-node input and wave propagation in the body of the soil as well as the pipeline have been taken into consideration. For this purpose a computer program, prepared by C++ coding has been developed for 2D structures, which can take into account axial, flexural and shear deformations of the pipe segments. The program can also consider the soil-structure interaction by modeling the pipe surrounding soil as mass-damper-spring systems, which are supposed to be connected to the centerline of the pipe. It is also possible to introduce axial as well as rotational springs between the pipe segments to model the flexibility of the pipe joints. The efficiency and precision of the developed computer program have been shown by comparing its results with those of ANSYS computer program. Several cross-sectional properties of the pipe as well as various conditions of the surrounding soil have been used in analyses to find out the effect of different parameters on the seismic behavior of pipelines. At first the damping value for the pipeline material has been considered as zero, and then some other values have been used to find out how this property affects the seismic response of the pipeline. In addition to the effects of pipe and soil properties on the pipeline seismic response the effects of the pipe element's length in the precision of the response values have been studied. Numerical results show that the relative stiffness of soil with respect to the pipe has the most powerful effect on the pipe seismic response. In other words, for each given pipeline some special soil condition makes the pipe seismic response very extensive. These values are quite different, in some ranges of input frequencies, with those obtained by assuming infinite value for the shear wave velocity in pipe material, which is the implicit assumption in the usual seismic analyses. Therefore, to achieve a reliable and economic design, it is necessary to consider both multi-node excitation and wave propagation phenomena in the earthquake analysis of the pipeline systems.

A GIS based geologic hazards assessment was completed for Chevron's product pipelines extending from Salt Lake City, Utah, to Boise, Idaho. The analysis involved gathering a significant volume of geologic data into a Geographic Information System (GIS) database. Ten hazards were modeled using criteria and weightings for individual inputs. Geologic and modeling algorithms were used to produce grid products for each hazard. Models included both qualitative interpretations for low hazard events, and quantitative evaluations of seismic and hydrologic hazards. The resulting GIS-based geo-hazard potential maps provided spatial qualitative and quantitative information on the geo-hazard potential and risk along a 317 mile long pipeline corridor.

The Hetch Hetchy Aqueduct delivers water from the Hetch Hetchy reservoir in Yosemite National Park to the City of San Francisco and other suburban municipalities in the greater San Francisco Bay Area. Typical flow rates are on the order of 270 to 315 million gallons per day. The aqueduct splits into four separate pipelines at the point where it reaches the city of Fremont. These are called Bay Division Pipelines (BDPL) 1, 2, 3 and 4, with nominal pipeline diameters of 60″, 66″, 78″ and 96″, respectively. All four pipeline cross the Hayward fault. At the fault, the pipelines are riveted steel (BDPL 1); double lap welded steel (BDPL 2); concrete cylinder with local steel sections (BDPL 3 and 4). BDPL 1 and 2 are aligned such that right lateral offset of the Hayward fault will produce net tension in the pipes. Pipelines 3 and 4 are aligned such that right lateral offset of the Hayward fault will produce net compression in the pipes.

The existing water distribution network of many established cities with growing urban population is vast and rapidly aging. An exposed water pipeline mounted on bridge constitutes a vulnerable portion of the pipeline network, and is often subjected to additional environmental forces and regulations by the bridge owners. Although, the mounting of pipes on host bridges is generally more economical than building of new independent pipe crossings, often the lack of understanding about the bridge's performance and bridge owner's requirements could be overwhelming to pipeline designers. A comprehensive set of guidelines addressing such issues on the planning, design, inspection, and maintenance aspects of water pipeline installations on host bridges was developed for the Bureau of Water Works of the City of Portland, Oregon. This paper briefly describes the development of the guidelines and provides an abstract version of the recommendations for the planning and design of such installations. A brief summary of proposed pipe hanger design criteria with design forces, load combinations, and safety factors are also included. The guidelines were specifically developed for personnel routinely involved in the planning, design, inspection, and maintenance of water pipelines without bridge engineering background. Many articles presented in this document can also be applied to other locations and non-water utilities mounted on bridges.

Gainesville Regional Utilities (GRU), located in Alachua County, Florida, experienced severe drought conditions dating back to 1999. The year 2000 was the driest on record for Florida. Coupled with 1999, the last 2 years have been the most arid on record since the 1930s, according to the National Oceanic and Atmospheric Administration's National Climatic Data Center. During the Past two years, GRU's service area has experienced a cumulative rainfall deficit in the vicinity of 40 inches. Record customer water demands during May and June 2000 placed a heavy burden on GRU's existing water supply and distribution infrastructure. This situation eventually required for the first time ever in GRU's service area the implementation of emergency water use restrictions for 158,000 customers.

Late in the design period for Caltrans freeway improvements, a physical conflict with the San Diego County Water Authority's Pipeline 3 at the State Route (SR) 125/94 interchange was discovered. Only two months were available to complete a preliminary design report for the relocation of the 69-inch (1752mm) prestressed concrete cylinder pipe (PCCP) pipeline and four months for completion of final plans and specifications. Completion of construction on schedule nine months later allowed Caltrans freeway construction to proceed on schedule. Six alternative alignments including both tunnel and open-cut under an overpass were evaluated. A tunnel alternative was developed that involved the purchase of a residential duplex for a tunnel shaft site. This saved Caltrans more than $1,000,000 in reimbursement costs over the next most favorable option and also avoided placing the final connection in an area with hydrocarbon-contaminated soils. The preparation of plans and specifications included the design of two tunnels, three vertical shafts, and two tie-ins to the existing Pipeline 3 at each end of the project. Variable geologic conditions ultimately required design for three separate tunneling methods, each of which was used. The greatest technical challenge was tunneling beneath the existing 69-inch (1752mm) PCCP Pipeline 3 with only 6 feet (1.83m) of cover, with pipeline settlement limited to 1/8 inch (3mm). Difficult connections to existing PCCP were designed at each end. Coordination with multiple jurisdictions included La Mesa, the County of San Diego, Helix Water District, and San Diego Gas & Electric on utility relocations and to permit the project. A permit was also obtained from the Regional Board for groundwater discharge.

Competition is defined as "the effort of two or more parties acting independently to secure the business of a third party by offering the most favorable terms". (Merriam-Webster; 2001). Without competition, a buyer (the third party referred to above) has no option but to resort to the one product or service offered, which could, mean poor quality and higher prices for him. Competition is encouraged to maintain quality products and services at reasonable prices. The business of engineering is no stranger to competition. Engineering firms compete for the business of a client, in turn contractors, vendors and suppliers all compete to provide the service proposed by the engineer for that client. The following is an example of an engineering project in which competition amongst the suppliers was stimulated while still maintaining the quality and integrity of the product. In 1999, the City of Corpus Christi, Texas awarded the Southside Transmission Main project to the team of Black & Veatch/Urban Engineering. Black & Veatch's project scope involved the design of approximately 13.7 kilometers (8.5miles) of 1524 mm (60-inch) and 1371.6 mm (54-inch) transmission main, which was the first of three phases in getting water to the Padre Island service area. The need for this transmission main was established in the Water Distribution System Master Plan prepared by Black & Veatch for the city of Corpus Christi, TX in 1997.

The significant design challenges included routing the pipeline through an active military base and designing the pipeline to withstand the loads of military vehicles, including the 65 metric ton A1M2 Abrams main battle tank. The rerouted pipeline consisted of 8,300 m of welded steel pipe with double welded lap joints. Seven bores of concrete tank trails and one bore of a main access road were required to minimize disruption to the base activities. Production rates for the installation of the pipeline ranged from an average of approximately 150 m per day to a maximum of 450 m per day. Construction techniques used to increase production included the use of a trapezoidal bucket to slope the trench sides and sand bags to set the pipe to grade. The controlled low strength material used for pipe bedding and pipe zone material was batched on site to ensure on-time delivery.

The San Diego County Water Authority (Authority) Capital Improvement Program (CIP) includes several projects requiring large diameter pipeline connections to the existing aqueduct system. Major portions of the San Diego Aqueduct that supplies water to 2.7 million residents and 23 member agencies in San Diego County, California (County) must be shutdown to complete these connections. Since approximately 95 percent of the County of San Diego's water is imported through the Authority's aqueducts, these connections must be completed in the shortest possible time following detailed construction plans and schedules so that water shortages do not occur. This paper will discuss the planning, design, construction and operational issues related to large diameter pipeline connections for the Authority's Twin Oaks Valley Diversion Structure project. This project included multiple large diameter pipeline connections that were completed in time frames as short as eight days. This project also include new cement mortar lines and cement coated (CMLC) steel pipe designed and constructed to connect to existing aqueduct pipe materials such as prestressed concrete cylinder pipe (PCCP). Partnering between the owner, engineer, construction manager, and contractor assisted in successful connections to the San Diego Aqueduct.

The Southern Peru Copper Corporation recently constructed a flood control project that diverts the Torata River into a conveyance system composed of a large concrete-faced rockfill dam, a tunnel, a pipeline, and a rock channel. The 3.5-Km (2.5-mile) pipeline segment of the conveyance system includes parallel, large-diameter HDPE pipes. The pipeline design objective entailed accommodating a 118-meter (387-foot) vertical drop and controlling flows and pressure without the use of valves or mechanical equipment. This design objective was accomplished through a series of outlet weir controlled drop sections. Incorporating hydraulic jumps into each of the pipeline drop sections was a critical design element. This paper summarizes the hydraulic analyses required to design the pipeline and compares the hydraulic jump calculations with field observations that have been made since recent project startup.

The County Sanitation Districts of Los Angeles County (Districts) operate and maintain a sewage collection system that includes approximately 1060 km (660 miles) of sewers made from unlined concrete pipe, which are susceptible to hydrogen sulfide corrosion. Ongoing inspections of the collection system have identified approximately 218 km (135 miles) of deteriorated sewers that would require either replacement or rehabilitation. In many cases where it would have been too costly or disruptive to replace a deteriorated sewer, rehabilitation using trenchless construction methods has allowed the Districts to extend its useful life of many sewers. To date, the Districts have awarded more than 50 contracts to rehabilitate more than 82 km (51 miles) of deteriorated sewers ranging from 203 to 2591 mm (8 to 102 inches) at a construction cost in excess of $105 million. Most of these projects have been completed successfully within the contract time and with few change orders.

AMEC Earth & Environmental, Inc. (AMEC) assisted Kinder Morgan Energy Partners, L.P. (Kinder Morgan) in planning and rehabilitating a 26-mile section of petroleum pipeline through Marine Corps Base, Camp Pendleton, San Diego County, California. AMEC used its Geographic Information System (GIS) database and a crew of biologists to identify a route for the pipeline that would minimize impacts to sensitive habitats. The pipeline impacted almost 100 acres of undeveloped habitats, including riparian woodland, freshwater marsh, sycamore grassland, oak woodland, and coastal sage scrub. It also affected a number of populations of a federally listed plant species. A land rehabilitation technique termed "imprinting" was used to seed the impacted pipeline corridor. The imprinter utilizes a track-mounted tractor with a rolling drum to create divots or microwells in which seeds and soil inoculum are injected to a depth of ¼ inch. Imprinting technology is a cost-effective and rapid tool for restoring large areas of impacted land and can increase rehabilitation success when compared to other restoration techniques by providing applied seeds a protected microhabitat in which to germinate and establish.

In order to improve the decision-making process in the choice of a rehabilitation technique of a small sewer networks, we propose to use an analysis based on a multicriterion method. After having introduced the principle of the choice assistance, we introduce the different families of rehabilitation techniques as well as some selection criteria. In this paper, the model to evaluate each criterion will be given and the multi-criteria approach explained.

The liner materials used for pipe renovation are usually designed to meet some minimum consensus standards. Often, the design guidance is listed in the Appendix of the standards. For additional guidance, numerous design manuals not part of the pipe standards are distributed by each vendor or technology holder uniquely geared to their own technology. There is clearly a lack of standardized design methods that allow direct comparisons between available materials or provide final designs on an equal performance basis. This paper will provide a unified design approach so that most no-dig pipe rehab liners are designed by the same set of engineering guidance. Engineering issues, pertaining to various loadings imposed on the liner, buckling behavior of the liner allowing for ovality, size of the annulus, wrinkles, annulus grouting, stresses and strains in the reliner pipe wall, are addressed. This paper would be of great interest to technology holders, owners of pipeline networks, pipeline asset managers, consulting engineers, and regulators.

Horizontal directional drilling (HDD) has become a preferred method for installing pipelines and conduits beneath rivers, roadways, airports and other sensitive areas. As the directional drilling technology has evolved, more challenging projects have been conducted especially in complex geological conditions including rock. Drilling in rock is achievable when correctly designed and constructed with the proper equipment and by experienced contractors. Rock crossings are considered to be difficult projects. Until recently, most projects using HDD were performed in alluvial soils or in river bottom deposits. In the last several years, more drilling projects have been attempted in rock. There are only a select number of construction contractors with hard rock drilling experience. This paper describes many of the challenges faced by the design and construction industry when installing pipelines in rock using directional drilling. Case histories are used to highlight the lessons learned by the designer, owner and contractor.

The City of San Diego is currently implementing a $773 million capital improvements program (CIP) designed to improve its water supply facilities and increase system reliability. The CIP, which was launched to facilitate completion of water treatment, storage and distribution system projects, includes over 50 projects scheduled for construction throughout San Diego County. The program is now beginning its fourth year. Projects are being rapidly implemented in all phases from planning through construction and start-up, with a number of projects having been completed and successfully placed on-line. Several major pipelines planned for construction involve trenchless construction crossings, including Miramar Road Pipeline, Miramar Water Treatment Plant Early Start Pipeline 2A, Rancho Bernardo Pipeline No. 2, and Alvarado Water Treatment Plant Upgrade and Expansion. A summary of these proposed projects is provided as well as discussions of lessons learned on other recently completed trenchless crossings in San Diego County.

Of concern to the Glendale Utility and Engineering Departments (Glendale), as it is to most utility and public works organizations, is the failure of system components and the consequences of such failure. A major objective for Glendale is to understand weaknesses in its system and to be proactive in addressing these needs before they become failures. System evaluation is one of the approaches used to identify system deficiencies. Another is to identify hazards and assess the risk associated with the hazards. Glendale is employing both approaches. Glendale has also found that it can greatly leverage the basic information it derives from the project through the use of proactive asset management tools.

This paper will highlight the various aspects of planning a pipeline rehabilitation project of bare or poorly coated steel pipeline to maximize resources. The paper will discuss in detail the aspect of pipeline data collection to make rehabilitation decisions, including intelligent pig data and its use, close interval survey and its use, hydrotest data and its use, etc. This paper will also review the analysis of the hydrotest data, the close interval survey data, and it's meaning to the overall rehabilitation design and plan. The paper will also assess the various types of pipeline coatings and methods of recoating and typical and innovative cathodic protection methods. The paper will stress analysis of pipeline structural integrity prior to making rehabilitation decisions. It will review cost estimating for various types of pipeline rehabilitation, and look at various alternatives. Finally, this paper will review typical results from various types of rehabilitation and soil conditions. It will emphasize the need to assess the results of the different rehabilitation methods and detail the results for future pipeline rehabilitation project decision making. The paper will discuss the use of RAP sheets (rehabilitation analysis profile) for data review and suggest various methods to invest rehabilitation dollars to get the greatest quantity of rehabilitation work done for the least cost.

The San Diego County Water Authority (Authority) is conducting condition assessments on all large diameter Prestressed Concrete Cylinder Pipelines (PCCP) and Steel Pipelines within their service area as part of the Authority's Aqueduct Protection Program (APP). Research of past fabrication and installation records is one component necessary to assess the pipeline's condition and estimate the remaining service life. This research has identified several fabrication and construction items which typically would not be documented as part of the project record. To ensure future pipeline condition assessments can be readily performed, the Authority has implemented a fabrication and construction inspection documentation plan for all new pipelines. This paper discusses components not typically documented during construction and provides examples of worksheets developed to aid construction management teams in reporting this information with minimal impact to their daily responsibilities.

This paper presents the development and advancement of digital optical scanning technology brought by the SSET. Chronological development history and evolution of the optical scanner technology is outlined. The inner works of the scanner and example outputs are provided. Advantages of the digital technology over the conventional analog CCTV are discussed. Also, this paper will provide details of the evaluation program utilized for the third-generation SSET system and the first commercial project for the Los Angeles County Public Works Department. This project involves the internal inspection of reinforced concrete pipe (RCP) damaged as a result of earthquake activity.

This paper discusses the interim conclusions from a AWWA Research Foundation sponsored study, which will determine the solutions to external corrosion of water pipelines. A companion paper discusses the causes of corrosion on buried water mains. Existing and new techniques for mitigating external pipeline corrosion, including those from other industries are discussed. A draft methodology has been developed for the water utilities to detect corrosive conditions, and either mitigate or design to minimize the risk associated with external corrosion. The methodology will be field tested and correlated with data obtained from utilities. Development of a better understanding of the benefits and value of corrosion control in the water utility industry is a primary goal. Specifically, a Corrosion Control Master Plan has been developed which incorporates use of systematic risk based approach to corrosion control whereby facilities with high costs of failure and/or high probabilities of failure are given the greatest attention. Work towards this objective has drawn heavily on the risk assessment methodologies developed for the oil, gas and nuclear industries.

Closed Circuit Television (CCTV) surveys are used widely in North America to assess the structural integrity of underground pipes. The video images are examined visually and classified into grades according to degrees of damage. The human eye is extremely effective at recognition and classification, but it is not suitable for assessing pipe defects in thousand of miles of pipeline images due to fatigue, subjectivity, and cost. This paper presents ongoing research into the automatic assessment of the structural condition of underground pipes for the purpose of preventive maintenance by municipalities. A simple, robust and efficient image-processing algorithm for the automated analysis of underground pipe scanned images is presented. The algorithm consists of gray-scale conversion followed by a sequence of morphological operations to accurately extract pipe joints and laterals (where a smaller pipe is connecting to the main). The extraction of joints and laterals is a crucial step in the detection of surface cracks in pipes, which can be analysed by subsequent filtering operation. The proposed approach can be completely automated and has been tested on over one hundred scanned images of underground pipes from major cities in North America.

In this study, a modified ground strain model is developed to apply an equivalent earthquake load for the seismic analysis of buried pipelines. The ground strain can be obtained using the ratio of maximum ground velocity to wave propagation velocity. To reflect soil conditions and seismic characteristics, the wave propagation velocity is evaluated by a proposed dispersion curve based on wave energy distribution. In order to verify the developed ground strain model, the results of this study are compared with the observed ground strains of earthquake data. The results of the analyses are compared with those of a dynamic analysis and a response displacement method. Finally various parametric studies considering different properties of pipelines are performed.

The objective of this paper is to present an innovative construction technology, developed in Japan, in which dredged material obtained from seabed, lake or navigation channels, is transported and stabilized in a pipeline using compressed air. One major concern in highly developed urban coastal areas is to obtain quality soil for various construction purposes. The need to supply engineered materials for construction purposes, and finding new applications for the dredged materials dumped into the disposal sites are the main reasons for developing this technique. The drawback of most stabilization work is the high cost of manufacturing process and transporting. Accordingly, in the technique presented here the process of manufacturing (i.e., mixing dredging with a stabilizer and other additives) and transportation are carried out in a pipeline using compressed air. The technique aims for effective use of marine resources for various construction purposes in the coastal areas, while reducing the construction cost due to mixing inside a pipeline. Additionally, an assessment of field feasibility of the technique is described along with the characterization of the geomaterial using in situ and conventional laboratory tests. Several application areas of the technology for infrastructure development or rehabilitation in the coastal areas are described. Pipeline mixing is more suited for producing large amount of engineered fill, especially for large-scale projects.

A section of underground pipeline subjected to inner pressure, temperature changes and corrosion wear is considered. Models and details of different corrosion processes are studied. This paper proposes a method of analyzing structural safety, taking into account the random values of corrosion effects and yield limitations, to optimize the reliability of pipelines used in aggressive environments.

This paper describes the expected operational performance of the City of San Diego Water Supply pipelines when exposed to possible future scenario earthquakes on the Rose Canyon, Silver Strand, La Nacion and Elsinore faults. The City of San Diego water supply system serves over 1,200,000 people and includes over 3100 miles of distribution pipelines. The pipeline system as currently installed is exposed to potential ground shaking, liquefaction, landslide and surface faulting hazards. The analyses conducted use a specialized GIS software package (SERA) that use geotechnical models that relate the probability of peak ground acceleration (PGA), peak ground velocity (PGV), and peak ground displacement (PGD) (settlement, lateral spread, fault offset) to the localized geologic hazards. The performance of the water system is analyzed on a pressure zone basis, with a total of 99 zones considered. The performance of the system is measured using a mitigation and cost benefit analysis technique considering life safety, fire loss, hospital and customer service requirements.

This paper analyzes the elastic behavior of buried steel pipelines subjected to a soil liquefaction event and presents a case study of a design project. Of primary concern are liquefaction potential, stresses and strain from settlement, and performance of the steel pipeline. A geotechnical investigation will provide project specific information of the liquefaction potential of the soils along the pipeline alignment. The earthquake induced dynamic settlement and differential settlement can be estimated based on the specific soil properties encountered in borings using conventional and empirical procedures. Once the differential settlement of the liquefiable soil is determined, the capability of the steel pipe to withstand the deflections can be analyzed. Maximum pipe deflection, stress from deflection, cross-sectional deflection, and bulking can be analyzed to determine the effects of the differential settlement of the soil on the steel pipe. A project currently in design is used to illustrate the capability of steel pipelines installed in liquefiable soils. The assessment of liquefaction potential and effects on the pipe were an important element in the selection of the pipeline alignment. Cross-country pipelines frequently cross rivers and other areas with potentially liquefiable soils. This paper will present design criteria that will assist in engineering solutions for the elastic behavior of buried steel pipeline installed in liquefiable soils.

When wastewater flows reach the 8- to 16-cubic feet per second, or cfs, (5- to 10-million-gallons-per-day [mgd]) range, the selection of gravity sewer pipe materials 15 to 25 years ago was limited basically to clay, concrete, and ductile iron. As flows went above 31 cfs (20 mgd), the choice of pipe materials for gravity flow was primarily concrete pipe. That was the case for the Water Works and Sanitary Sewer Board of the City of Montgomery, Alabama (Board), in the mid-1970s when it installed more than 21,950 meters (72,000 linear feet) of reinforced concrete sewer pipe of diameters ranging from 76 to 168 centimeters (cm), or 30 inches to 66 inches, in the Board's Catoma Basin. Concrete sewer pipe and manholes can have a life expectancy of greater than 50 years under certain environmental conditions. However, concrete sewer pipe and manholes are vulnerable to hydrogen sulfide (H₂S) attack and to varying degrees of subsequent corrosion during the seasonal temperature cycles. For concrete sewer pipe in warmer climates or pipe that experience 3-month periods that average greater than 20 degrees Celsius (°C), the concrete should be protected; otherwise, the pipe could fail in as few as 10 to 15 years in aggressive H₂S environments. The Board's Catoma Wastewater Treatment Plant (WWTP) will have influent temperatures that average 26 to 28 °C over a consecutive 3-month period. This temperature range usually occurs in June, July, and August.

This paper discusses the interim results and conclusions from an AWWA Research Foundation sponsored study, which will determine the causes of and solutions to external corrosion of water pipelines. A companion paper discusses the interim solutions to corrosion on buried water mains. A detailed literature review was conducted that encompasses relevant industries with corrosion control experience. A nation-wide water utility survey was conducted which focused on corrosion and corrosion control which confirmed that the water utility industry has a unique perspective on corrosion and corrosion control as compared to other industries that regularly implement corrosion control. The fundamental mechanisms of corrosion are well known. Corrosion of metals is a well-understood electrochemical process that results in the degradation of a material or its properties by its environment. For buried metals, corrosion is the result of the formation of anodic (corroding) and cathodic (noncorroding) areas of electrically continuous materials in a common electrolyte (soil). The difficulty is that the resulting corrosion damage at the anodic area of the pipe can be similar in appearance for different causal factors. The question is not how corrosion occurs, but more specifically, under what conditions encountered in the water utility industry does corrosion rear its ugly head.

Corrosion impacts the design, operation and maintenance of every element of a water system, water wells, treatment equipment, storage facilities and piping systems are all vulnerable to accelerated deterioration from corrosion. Numerous studies have been published that document the causes of corrosion and successful methods of control. The problems related to corrosion in water systems are not new. As early as 1939, the results from a survey performed by the Illinois State Water Survey indicated that 41% of the water systems responding were experiencing corrosion problems involving well pumps, water mains, storage facilities and service lines. Over the years, the basic problems have changed very little, although our understanding and technology for controlling corrosion have improved significantly. Corrosion in water systems must be addressed by every operator to ensure economical supply of high quality water and safe operation of fire protection systems. By properly addressing corrosion mitigation through material selection, coatings and cathodic protection, system life will be extended and operational costs reduced. The economic benefits accrue to both the system operator and ultimately the consumer.

TransCanada Pipelines Ltd. (TransCanada) owns and operates over 38,000 km of pipeline facilities, geographically situated throughout Canada and portions of the USA. These facilities cross diverse terrain such as the Rocky Mountains in the west, the flat prairies of central Canada and the Canadian Shield in Ontario and Quebec. Within the complex geographic terrain are numerous hydrologic regions that contain over 2700 pipline crossings of creeks, rivers and lakes. Many of these crossings have been subject to some form of streambed degradation and coupled with extreme flooding events, have resulted in reduction of cover over the pipeline and/or exposed pipeline crossings. These hydraulic conditions can further threaten the integrity of an exposed pipeline crossing when subjected to vortex shedding, horizontal load or impact from floating debris. Historically 8 exposures have been identified and investigated in Alberta and 3 of them have been chosen as case studies for this presentation (the South Saskatchewan River, the Red Deer River and the Simonette River). Each case study will detail the following; historical events leading up to the incident, hydrotechnical analysis, the decision processes the design approach and implementation.

Scour problems have been identified at many pipeline crossings of rivers and streams. Some of these pipelines have become exposed or undermined as a result of bed degradation over time or from intermittent flood flows. Once exposed or undermined, pipelines can fail or be damaged due to debris and anchor impact or from the spanned weight of the pipe. An extensive review of literature on scour depth calculation methods has been conducted. The calculation of scour depth, bed form height, stable material size and critical slope angle have been compiled to form a method of analysis and design. This method involves the analysis of potential bed lowering and the design of granular armor blankets at pipeline crossings of mobile-bed rivers and streams. This method of analysis is not a replacement for a three-dimensional hydrodynamic model and judgment should be made by the engineer as to whether this analysis is appropriate to the crossing of interest.

Prestressed concrete cylinder pipes are used for water intake lines. Many burstings were observed even after only few years of service. In this paper, we present the results of numerical modeling and a proposal for the rehabilitation of a pipeline were many incidents and damages were observed. The aim of our modeling is to contribute in the elaboration of a reliable global approach permitting to understand the mechanical behavior of the PCC pipeline.

It is possible to manage the risk in operating a PCCP pipeline effectively. Performing an assessment of the actual condition of each pipe and examining the hydraulic loads experienced under various operating conditions allows predictions to be made regarding the failure point of each pipe. By prioritizing the pipe sections by the likelihood and consequence of failure, a cost effective rehabilitation and/or replacement strategy can be developed. By determining the causes for the distress, a corrective plan may be implemented and monitored through periodic and/or continuous monitoring of sections of the pipeline.

The Muskegon County Wastewater Management System 66-inch-diameter prestressed concrete cylinder pipe pipeline that carries raw domestic and industrial sewage experienced four failures to date. The entire line is without back up and cannot be removed from service without enormous economic and environmental consequences.. The pipeline lacks any entry ports for personnel or equipment along its length and no part of it can be isolated. All investigations and the pipe condition assessment had to be done from outside only. The condition assessment study, performed following the pipe failure investigation, included inspection and testing the pipe exterior at test pits, material testing, soil resistivity survey, soil chemical analysis, geotechnical investigation, hydraulic surge analysis, and structural analysis of the pipe subjected to surge pressures. An evaluation system based on a database of potentially adverse parameters to PCCP performance was developed. Concentration of adverse parameters in an area of the pipeline was an indication of an increased risk of failure. A strategy to mitigate the risk of failure was developed considering the low tolerance for and the high cost and environmental impact of pipe rupture. The recommendations were made to replace a part of the pipeline, and to monitor the rest.

This paper describes the development, application, testing and results of a continuous acoustic monitoring system used to detect and locate corrosion-induced failures in approximately 1,800m (6,000 feet) of 105cm (42 inch) prestressed concrete pipe owned and operated by Howard County Maryland, Department of Public Works. A SoundPrint® acoustic monitoring system was installed to assess and analyze the condition of this and other critical potable water conduits. The results of this evaluation and subsequent excavation to confirm deterioration detected by the system are discussed.

As the age of our pipeline infrastructure increases, non-destructive evaluation becomes more and more important. A new electromagnetic technique called remote field eddy current/transformer coupling (RFEC/TC) has been developed to meet the NDE inspection needs of prestressed concrete cylinder pipe. The method has been used successfully to detect prestressing wire failures in PCCP. This paper explains the technology and presents recent test results and field applications. Case study describes the updated inspection experience with several pipeline owners, and demonstrates tile benefits of RFEC/TC inspection.

The purpose of this paper is to provide an overview of assessment methodologies used for Prestressed Concrete Cylinder Pipe [PCCP] in Calleguas Municipal Water District [CMWD] as part of the Infrastructure Reliability Program [IRP]. CMWD annually supplies 1.233 x 10⁸ m³ [100,000 acre-feet] of imported State Project Water to Ventura County, CA through Calleguas' 208 km [130 miles] of transmission pipelines. Forty kilometers [25 miles] of these pipelines are PCCP, in nominal sizes ranging from 1.22 m [48″] to 1.98 m [78″], with installation dates between 1964 and 1982. In 1997, a failure occurred in one location on a 1.68 m [66″] PCCP pipeline. After making repairs due to a catastrophic break in 1997, CMWD initiated the IRP to ensure the structural integrity of the PCCP lines, which are the backbone of CMWD's distribution system. This paper discusses the assessment portion of the IRP which have been undertaken. Assessments have included: 1) internal inspections by sounding, impact echo and remote field eddy current transformer coil techniques, 2) in-service monitoring using acoustic emission, 3) soil corrosivity analysis using electromagnetic conductivity surveys and soil chemical analysis, and 4) Close interval potential surveys and line current mapping. In addition, transient surge analysis of the distribution system has been completed and modifications are underway to minimize events in the system. The product of the assessments identifies section(s) of PCCP pipelines "at risk" and assists in repair/replacement decisions. Repair options and methodologies are the subject of another paper.

The condition and rate of deterioration of prestressed concrete cylinder pipe (PCCP)is a concern for owners and managers of these facilities. New developments in condition assessment technology provide more information regarding the present and future condition of these structures. This paper describes the development of a web-based application to monitor in real-time the condition of these structures. Data presented on-line can include existing pipeline information (half-cell potentials, internal/external inspections, electromagnetic testing data, etc.) coupled with dynamic information provided by acoustic monitoring and operational parameters such as pressure. Sophisticated proprietary software analyzes the acoustic data to determine the time, location and classification of events. Reports can be generated on-line summarizing activity in a structure over a specified period. Remote diagnostic capability through a web browser ensures optimum system operation. It is possible to continuously monitor critical sections of prestressed pipe incorporating base line and rate of deterioration information. This comprehensive reporting protocol provides owners of these structures, the ability to budget and plan for preventative pipe repairs or replacement.

Condition of existing buried pipelines with prestressed concrete cylinder pipe (PCCP) from standpoint of number of broken wires can now be determined accurately using the remote field eddy current/transformer coupling (RFEC/TC) non-destructive test method. The test provides the owner with information about wire break locations and the number of broken wires in each location. The purpose of this paper is to evaluate the risk of rupture for the reported number and location of broken wires for a pipe subjected to specified pressures, and to determine the repair priority for pipes with broken wires. PCCP derives strength from prestressing wires, and loss of prestress due to wire breakage poses a risk of pipe rupture that depends on the number of broken wires, location of broken wires, original pipe design, and maximum pressure likely to occur in the future. Risk of failure of a pipe is evaluated by comparing the maximum pressure expected in the line with the pressure required to cause rupture. The pressure required to cause rupture in a pipe with broken wires is calculated by computing the pressure that causes tensile softening of concrete in the circumferential direction, and exceeds the bending capacity of the outer core in the longitudinal direction and rupture strength of the steel cylinder. The calculation accounts for interlocking and arching effect of cracked concrete and for soil resistance against radial movement. Application of the above technique to the risk assessment and repair priority of several prestressed concrete pipelines with broken wires is discussed.

This paper describes Calleguas Municipal Water District's [Calleguas] recent rehabilitation activities on Prestressed Concrete Cylinder Pipe [PCCP]. Calleguas annually supplies 1.233 x 10⁸ m³ [100,000 acre-feet] of imported State Project Water to Ventura County, California through Calleguas' 208 km [130 miles] of transmission pipelines. Forty kilometers [25 miles] of these pipelines are PCCP, in nominal sizes ranging from 1.22 m [48″] to 1.98 m [78″], with installation dates between 1964 and 1982. In 1997, a catastrophic break occurred in one location on a 1.68 m [66″] pipeline. After conducting immediate repairs to place the line back in service, Calleguas initiated a program of evaluation and rehabilitation to ensure the structural integrity of the PCCP lines, which are the backbone of Calleguas' distribution system. This paper will discuss the types of rehabilitation and repair activities performed by Calleguas since 1997, including pipe replacement, steel cylinder lining, and carbon fiber lining. Each has advantages and disadvantages, and each has its place in a program for PCCP rehabilitation.

Calleguas Municipal Water District initiated their Infrastructure Reliability Program (IRP) in 1997 after repairing a catastrophic failure of a 66-inch diameter prestressed concrete cylinder pipeline (PCCP). The IRP includes tasks to assess the condition of the existing PCCP in order to prioritize and rehabilitate deteriorating sections of the transmission system. Condition assessments have been conducted using visual inspections, acoustic techniques, and remote field eddy current/transformer coupling testing equipment on approximately 5 miles of the system. Forensic studies conducted on the damaged pipe indicated that the failure was probably the result of hydrogen embrittlement of the prestressing wire induced by an impressed current cathodic protection system. Pipe rehabilitation was prioritized and sections of 78-inch and 66-inch pipe were replaced in 1998 and 1999.

The San Diego County Water Authority (Authority) is a water wholesaler delivering imported water to the San Diego region. The imported water is delivered through several large diameter pipelines, sized up to nine-feet in diameter, to meet 70 to 90 percent of the regions annual demand. As part of the Authority's mission "to provide a safe and reliable supply of water to San Diego County", and to mitigate deteriorating pre-stressed concrete cylinder pipe (PCCP), approximately 686 meters (2,250 feet) of welded steel liner was installed inside the Second Aqueduct's 1753 mm (69-inch) diameter Pipeline 3. Installation occurred in the community of Rancho Penasquitos within the Authority's right-of-way. The pipeline was taken out of service to perform liner installation. An aggressive construction schedule of six months was implemented to restore service to Pipeline 3 and to meet seasonal demand increases on the Aqueduct System. Liner installation was identified during project design as the critical task for completion of construction on schedule. The Authority's estimated construction schedule allowed for installation of three liners per day, or approximately two months total, leaving four months to complete all other construction tasks.

The Windy Gap Pipeline is a 9100-meter (30,000-foot) long, 2750 mm (108-inch) diameter pressure pipe. Approximately 7300 meters (24,000 feet) of this line is prestressed concrete cylinder pipe (PCCP). Given the problems experienced with numerous PCCP pipelines throughout the country, the owner, Northern Colorado Water Conservancy District, desired to perform a condition assessment on this portion of the pipeline. A phased condition assessment program was conceived to cost-effectively eliminate areas of concern that have historically been problems for PCCP. Initial testing indicated that the pipeline was surrounded by a relatively benign environment with no apparent distress or corrosion. However, wire testing results indicated highly variable properties with moderately strain aged wire. A remote field eddy current /transformer coupling assessment technique was employed to determine the extent of the wire problems on the pipeline. Results showed that 275 pipes had 5 or more broken wires, with 4 pipes containing over 50 broken wires. An external tendon repair was designed and constructed on 17 sections of pipe that were likely to fail. During the course of this project, several issues involving interpretation of test results, limitations of tendon repairs, and cost/benefit analysis of rehabilitation methods arose that highlight the challenges faced by PCCP owners relating to the emergence of new assessment technologies and rehabilitation methods.

This recently completed 440-meter river crossing in Korea advance through 65 meters of rock not exceeding UCS 1200 kgf/cm², 130 meters of soft clay, silt, and sand not exceeding N=30, and 220 meters in rock ranging between UCS 400 – 600 kgf/cm². The river crossing, utilizing 1778-mm OD x 19-mm Wall x 6000-mm steel casing pipe without intermediate jacking stations, was part of a 7 kilometer LNG transmission line. The was completed without changing disk cutters or using the airlock. The airlock was incorporated into the machine design because of the long drive.

Microtunneling has successfully completed both horizontal and vertical curves. This paper will focus on the machine and pipe design requirements for the successful completion of a curved pipe jack utilizing a microtunneling machine specifically designed for the completion of the job. The specific project, completed in Japan, included two right handed curves, two left handed curves and a one vertical curve all in a single drive. The project utilized reinforced concrete jacking pipe as manufactured in Japan to Japanese standards. This paper will also briefly discuss the historical development of curved microtunneling, a brief description of this project including soils information, and project design requirements. In order for this drive to meet all of the imposed restrictions, four horizontal curves and one vertical curve were planned and executed in this man entry sized tunnel. The machine was manufactured by Iseki to meet the project requirements.

Reconstruction of 2,224m (7,000 feet) of a 900mm (36-inch) diameter major trunk sewer in downtown Honolulu and historic Chinatown is required to replace aging, corroded and sagging sewers. Construction of this pipeline through the most congested urban area in Hawaii is extremely difficult. This paper discusses some of these key construction challenges and describes how they were resolved.

Pipelines of large diameters are used for water supply, drainage sewers, and gaslines. Steel pipes are commonly used for such large diameters. These pipelines are considered as flexible for high D/t ratios of the order of 100 to 200 i.e., very small thickness. The design of flexible pipes is done considering internal and external loads, material and backfill characteristics. It is recognized that uncertainties cannot be avoided in the design and construction of buried soil structures and the role of uncertainties in specifying design limits such as factor of safety or tolerable deflection limits needs to be understood. To take care of the uncertainties, while the conventional methodology incorporates arbitrary factors of safety for deflection and buckling, it is important that these aspects of variability be incorporated in design. Reliability analysis plays a major role in considering the uncertainties influencing the design of underground flexible pipes. The purpose of this paper is to highlight some of these factors. The present study considers the uncertainties in load (coming from backfill) and the soil reaction modulus for two modes of failure 1)Deflection and 2)Buckling. In the following sections, difficulties with the conventional approaches are reviewed and the uncertainties in design of buried pipes are highlighted. Reliability analysis is performed for a typical buried pipe using point estimate method and the probabilities of failure are evaluated.

This paper presents the results of field tests that were conducted to reveal the mechanical behavior and application of large diameter flexible pipe buried in shallow cover with countermeasures against pipe flotation by the use of geogrids. In the field tests, two lines of 2400mm diameter flexible pipe were installed with 1.5m cover. Pipe behaviors during construction, and mechanical behavior of the pipes and bedding during an incipient flotation event due to raised groundwater levels, are discussed. After one-year of measurements, the results indicate that the deflection of the pipes is less than 1% of their diameter and the force acting on the geogrid is about 10% of the goegrid's ultimate strength. In the field tests, backfill materials wrapped by geogrid had high bearing capacity during construction and were effective in preventing large diameter pipe deflection. This shallow cover method with geogrid demonstrates a large resistance force against pipe uplift with soil cover at 60% of pipe diameter, and a stable performance of the geogrid unified backfill.

In this study, a numerical model is developed for the analysis of buried pipeline considering longitudinal PGD due to liquefaction induced lateral spreading. Buried pipelines and surrounding soils are modeled as a continuous pipeline using beam elements and a series of elasto-plastic springs uniformly distributed along the pipeline, respectively. Idealized various PGD patterns based on the observation are used as a loading configuration and the length of the lateral spreading zone is considered as a loading parameter. Numerical results are verified with other research results and efficient applicability of the developed procedure is shown. Analyses are performed by varying different parameters such as PGD pattern, pipe diameter and pipe thickness. Finally, tile critical length of the lateral spreading zone and the critical magnitude of PGD which cause local buckling failure are proposed for the steel pipe which are normally used in Korea.

Corrpro's Break Reduction/Life Extension (BRLE) program for cast and ductile iron water pipe derives primarily from life extension programs that have been and are presently being successfully implemented throughout Canada by various water utilities. The Canadian experience dramatically illustrates the significant capital and repair monies that can be saved by implementing such a program. The key elements of the BRLE program include: (1) an upfront corrosion assessment of the water distribution system and; (2) installation of galvanic anodes in selected areas of the water distribution system based on the corrosion assessment. The corrosion assessment ordinarily includes a review of the water system's general characteristics (e.g. age, material, pipe wall thickness, construction practices, etc.), a review of its break/leak history, a field survey (e.g. soil conditions, electrical tests), and, when appropriate, inspection of the pipe at selected bell-hole excavations. The data are then analyzed to develop a priority indexing for the water system. The priority indexing identifies and prioritizes opportunities for economically reducing replacement/repair costs by installing galvanic anodes in selected areas of the water system.

The Newton Sanitary Sewer and Underdrain Separation project is the largest cured-in-place-lining project undertaken in New England. The project utilizes a multi-faceted approach to remove infiltration and inflow (I/I) from the sanitary sewer while simultaneously reducing the potential for sanitary contamination of local receiving waters. The project area consists of approximately 27,432 meters (90,000 feet) of 30.48 centimeters (12″) to 60.96 cm x 91.44 cm (24' x 36') sanitary sewer lines with 15.24 cm to 45.72 cm (6″ to 18″) underdrains. Constructed in the late 1800s, the underdrains were originally used for de-watering during construction. Underdrains are pipes with open joints that were installed beneath the sewer line to convey groundwater to a local drain or water body. These underdrains are connected to the sanitary sewer through "access points" located inside sanitary manholes. The access points were built to provide locations to perform maintenance on the underdrain piping system. Over time, these access points deteriorated, resulting in a direct connection between the sanitary sewer and underdrain. The direct connection allowed sanitary flow to enter the underdrain system and groundwater from the underdrain system to enter the sanitary system. This mixing of flows between the two (2) systems results in sewer overflows during extreme wet weather events, increased sewer user costs, and contamination of local receiving waters.

Leucadia County Water District (LCWD) is a California special district providing wastewater collection services to 52,000 people in North San Diego County. The service area is split between the Cities of Encinitas and Carlsbad. LCWD has 13 wastewater pump stations. The second largest pump station is the Leueadia Pump Station. This pump station has an ultimate peak capacity of 37.85 million liters per day (10 million gallons per day). LCWD unexpectedly experienced a 600mm (24-inch) diameter ductile iron force main failure in December 1998 in the shopping center parking lot adjacent to the pump station. Emergency retrofit conversion of an even older 300mm (12-inch) line allowed a temporary partial by-pass during repair.

This paper presents a case study of a gas pipeline project in a highly congested area where conventional installation techniques were not physically or politically feasible. The project, located in the city of Antioch, California, consisted of installation of 2 miles of 16-inch and 5 miles of 24-inch diameter pipeline sections to supply natural gas to two new power plants being built along the San Joaquin River. Limited workspace and environmental concerns along significant portions of an identified right-of-way required utilizing the Horizontal Directional Drilling (HDD) and other trenchless techniques. Acquiring geotechnical information along the pipeline alignment was important to the design and cost considerations for this project. Construction of the pipeline was completed in 2000 using HDD, slick bore, and conventional trench and bury methods. Several of the HDD crossings for this pipeline are near world-record length for the pipeline diameter.

This paper provides information on how the use of new technologies (i.e. HDD, microtunneling, and jet grouting) can be beneficial in solving complicated site geometry, geology and social environmental issues. It demonstrates that the uses of a combination of pipe materials and construction techniques can be utilized to provide an economical solution to a project.

The City of San Diego (City) is currently in the fourth year of implementing a $773 million capital improvements program (CIP) designed to improve its water supply facilities and increase system reliability. The program was launched on the heels of completing the City's Strategic Plan for Water Supply, which established a plan for system improvements and formed the basis for approval of a water rate increase to fund capital expenditures over an eight-year period. In implementing the program, the City faced the growing challenge of expediting design and construction of multiple projects simultaneously. Contracting strategies were pursued which expanded the City's capability to rapidly initiate both current and future projects. Alternative strategies included job order contracting, pre-purchase of long-lead items and design build. Upon contacting the Design Build Institute, the City was unable to find even one major large diameter municipal pipeline, which had been designed and constructed using the design build contracting method. Investigation of the advantages and disadvantages of the process identified no significant reasons why design build should not be employed on pipeline projects. Building upon favorable precedents experienced by San Diego in design build of several prior non-pipeline) projects, the Water Department in May of 2000 earmarked the Rancho Bernardo Pipeline No. 2 and Black Mountain Ranch Reclaimed Water Pipeline project for design build implementation. Between June of 2000 and February of 2001, the City was engaged in selecting the design build firm and issuing a notice to proceed.

The main objectives of the public involvement (PI) program varied as to project phase. During planning and route selection, the main objective was to obtain consent to construct. To obtain consent, the project team focused on communicating the problem the project would solve, that CWRWS had evaluated alternatives, and that acceptance of minimal disruption would solve a significant problem. During PI meetings in this phase, the project team was able to identify specific needs of affected residents that would assure their active consent to the project. These needs included curb and gutter repair, full-width street resurfacing or reconstruction, utility improvements, and other tangible benefits to individual property owners. While these improvements were beyond the scope and funding of CWRWS, the City of Casper took note of the public's needs and the two agencies developed a jointly funded project. This cooperation of public agencies to the benefit of the public further strengthened public support for the project.

This paper explores corrosion and its prevention through the use of cathodic protection. It defines the principles of cathodic protection and explains in a simplified way how cathodic protection can mitigate corrosion. It should eliminate the misunderstandings about the complexity and perceived expense of the installation of cathodic protection systems. Cathodic protection is a proven technique for mitigating corrosion. There is nothing mysterious or cryptic related to diminishing corrosion on metallic pipelines with this technology.

The author has been involved as an expert witness in numerous pipeline failure claims and lawsuits involving many millions of dollars in losses. When a pipeline failure occurs, the design engineer, owner, contractor, and pipe supplier invariably are involved in litigation. Most of these cases could have been avoided or minimized if a few simple details had not been neglected. This paper reviews some of the more common root causes that lead to pipeline failures and litigation. In most cases, the cost of the remedy, or action that could have been taken to prevent the failure represents a tiny fraction of the amounts involved in the cost of settling a claim. Everyone even remotely connected with the project is expected to "put something in the pot." In case after case, though the details may vary, the causative factors are closely related. Recommendations are made which will either help to keep the pipeline design engineer, owner, contractor, and pipe supplier out of court, or will help to minimize the potential losses as much as possible. An extensive bibliography is included of pipeline design manuals and related publications.