Evaluating the risk of water distribution system failure: A shared frailty model

Abstract

Condition assessment (CA) Modeling is drawing increasing interest as a technique that can assist in managing drinking water infrastructure. This paper develops a model based on the application of a Cox proportional hazard (PH)/shared frailty model and applies it to evaluating the risk of failure in drinking water networks using data from the Laramie Water Utility (located in Laramie, Wyoming, USA). Using the risk model a cost/benefit analysis incorporating the inspection value method (IVM), is used to assist in making improved repair, replacement and rehabilitation decisions for selected drinking water distribution system pipes. A separate model is developed to predict failures in prestressed concrete cylinder pipe (PCCP). Various currently available inspection technologies are presented and discussed.

Keywords

condition assessment / risk / failure

References

[1] Brechling V J (1995). A methodology for the economic assessment of nondestructive evaluation techniques used in aircraft inspection. Report no. DOT/FAA/AR-95/101 National Technical Information Service (NTIS), Springfield, Virginia 22161, USA.

[2] Clark R M, Carson J H, Thurnau R C, Krishnan E R, Panguluri S (2010). Condition assessment modeling for distribution systems using shared frailty analysis. JAWWA, 7(102): 81-91

[3] Clark R M, Sivaganesan M, Selvakumar A, Sethi V (2002). Costs models for water supply distribution systems. J Water Resour Plan Manage, 128 (5): 312-321

[4] Galleher J J Jr P E, Holley MShenkiryk M, Eaton G (2007). Snap, crack, pop-Recording of a prestressed pipe failure. Advances and Experiences in with Trenchless Projects, ASCE, 1-9

[5] Higgins M SGadoury, Razza R, Mead I (2007). Technologies to assess and manage providence’s water’s 102 inch PCCP aqueduct. Advances and Experiences with Trenchless Projects, ASCE, 1-8

[6] Lam K F, Kuk A Y C (1997). A marginal likelihood approach to estimation in frailty models. J Am Stat Assoc, 439 (92): 985-990

[7] Padewski E, Leshner N, Woodcock M, Higgins M (2007). Assessing PCCP transmission mains. Pipelines Specialty Conference, ASCE, 1-6

[8] Rajani B, Kleiner Y (2004). Non-destructive techniques to determine structural distress indicators in water mains. In Evaluation and control of Water Loss in Urban Networks, Valencia, Spain June 21-25, 1-20

[9] Rogers P D (2006). Failure assessment model to prioritize pipe replacement in water utility asset management. A thesis submitted in partial fulfillment of the requirements for the Degree of Doctor of Philosophy, Colorado State University

[10] Royer M D (2005). White paper on improvement of structural integrity monitoring for drinking water mains. National Risk Management Research Laboratory, Office of Research and Development, USEPA, Cincinnati, OH 45268.

[11] USEPA (2007). Distribution system inventory, integrity and water quality. Office of Water, Washington DC

[12] Wall M, Wedgewood F A, Martens W (1998). Economic assessment of inspection-The inspection value method. NDT.net, 3(12).

Acknowledgments

The US Environmental Protection Agency, through its Office of Research and Development, funded, managed and collaborated in the research described herein. It has been subjected to the Agency’s administrative review and has been approved for external publication. Any opinions expressed in this paper are those of the author(s) and do not necessarily reflect the views of the Agency, therefore, no official endorsement should be inferred. Any mention of trade names or commercial products does not constitute endorsement or recommendation for use. The authors wish to acknowledge the following individuals for their assistance in preparing this manuscript: Peter D. Rogers University of Texas-Tyler, Neil S. Grigg, Professor Colorado State University, and Cal Van Zee, Laramie Water, Laramie Colorado.

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