TECHNICAL PAPERS


ASSET MANAGEMENT FOR SEWER SYSTEMS

April 26, 2016

Traditional methods of wastewater condition assessment focuses almost exclusively on the gravity system and valve actuation, using tools such as smoke testing, CCTV, and zoom cameras. While effective on gravity mains and valves, these methods are not applicable in force mains. Inspecting force mains is more challenging due to lack of redundancy, lack of access points, cost, technology limitations, while the consequence of force main failures can be significant financially, environmentally and socially.

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WHAT'S IN THE NUMBERS? A REVIEW AND ANALYSIS OF MORE THAN 400 MILES OF FORCE MAIN INSPECTION AND CONDITION ASSESSMENT DATA

November 1, 2014

Comprehensive condition assessment of wastewater force mains provides significant challenges to owners/operators of collection systems as the ability to shut down or expose the pipeline for a thorough inspection is often impractical due to operational and/or financial considerations. Traditional gravity sewer inspection techniques (i.e. visual based technologies) do not always transfer easily to their wastewater pressure pipe counterparts and visual assessments do not provide the structural condition of force main – something that is critical in determining the true pipe condition. Therefore, a different set of inspection tools and assessment techniques is required for force mains.

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NUMBERS DON’T LIE, PCCP PERFORMANCE AND DETERIORATION BASED ON A STATISTICAL REVIEW OF A DECADE OF CONDITION ASSESSMENT DATA

October 24, 2014

Since the late 1990s there have been numerous inspection and monitoring projects focused on identifying and quantifying wire break damage in PCCP water and wastewater pressure mains.

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FAILURE RISK OF BAR-WRAPPED PIPE WITH BROKEN BARS AND CORRODED CYLINDER

October 1, 2014

This study investigates the behavior of a deteriorating BWP under various levels of distress and various internal pressures. The results based on a 24-inch pipe transmission main, are used to define criteria to evaluate the performance of a damaged BWP. Based upon the finite element results obtained in this study, suggestions for future work are presented and discussed.

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REVISITING THE TOPIC OF LIABILITY FOR DAMAGE DUE TO WATER MAIN BREAKS OR LEAKS

September 1, 2014

The topics of liability and negligence as they relate to water main failures are discussed from both a historical and current viewpoint. The historical perspective is provided in a 1948 Journal AWWA article, and we consider changes in liability issues from that time to the present. Case studies from various states are also presented that will provide water utilities insights into sovereign immunity and what constitutes discretionary function.

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DEVELOPMENT OF A LONG DURATION, FREE SWIMMING, INLINE ACOUSTIC LEAK DETECTION INSPECTION TOOL

December 1, 2013

Acoustic leak detection inspection tools have become a common technique to identify minute pipeline leakage before the leak and the defect producing it can become a larger problem or even a rupture level event. While these inspection tools only identify small defects once they reach the through wall stage and result in leakage, they can be an effective means of demonstrating the pressure tightness of a pipeline and ruling out the presence of through wall defects that are below the detection threshold of other ILI inspection tools; in so doing finding a way into both the leak detection and pipeline integrity toolboxes.

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BEYOND THE WIRES: A SUSTAINABLE APPROACH TO PRESTRESSED CONCRETE CYLINDER PIPE MANAGEMENT

March 6, 2013

While evaluating wire breaks are an important part of PCCP management, it is important to acknowledge additional factors beyond wire breaks. By acknowledging additional condition factors, limitations of wire break assessment, and considering other rehabilitation approaches, there may be a more sustainable PCCP management approach (or combination of approaches).

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AN ADVANCED METHOD OF CONDITION ASSESSMENT FOR LARGE-DIAMETER MORTAR-LINED STEEL PIPELINES

December 1, 2010

This paper describes the development and application of an advanced method of condition assessment for large-diameter, cement mortar-lined steel pipelines operated by the Hetch Hetchy Water and Power Project of the San Francisco Public Utilities Commission.

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WHEN TO INTERVENE? USING RATES OF FAILURE TO DETERMINE THE TIME TO SHUT DOWN YOUR PCCP LINE.

December 1, 2010

Performing structural evaluations of aged civil engineering structures has traditionally been performed on a static basis. The condition of the structure is tested either destructively or non-destructively to determine its present day condition and the strength is evaluated to determine if the structure can safely withstand anticipated loads. One of the problems with managing structures in this fashion is that structures do not behave in a static fashion. This is especially true for large diameter PCCP (Prestressed concrete cylinder pipeline) mains that have wire break damage resulting from corrosion or cracking from hydrogen embrittlement. Given the variability in rate of deterioration in a PCCP main the risk associated with a pipe section changes with time. Pipe sections where risk is deemed to be acceptable may change to a point where risk is not acceptable in a relatively short duration of time. This phenomenon has been observed on multiple pipe sections. This paper examines the rate of deterioration of PCCP mains to evaluate how risk changes or does not change with time and how this information can be used to determine when a pipeline should be repaired.

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