AWWA 20744-2012 Managing Water Main Breaks Field Guide.pdf

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1、 Blank PageManaging Water Main Breaks Field GuideManaging Water Main Breaks Field Guide Kenneth C. Morgan, PE The Authoritative Resource on Safe WaterManaging Water Main Breaks Field Guide Copyright 2012 American Water Works Association All rights reserved All rights reserved. No part of this docume

2、nt may be reproduced, transmitted by any means, or stored in any database format without the prior written permission of the Publisher, except where permitted by law. Disclaimer The intent of this publication is to provide guidance and thoughts for consideration in the subject matter covered. It is

3、for purchase with the understanding that neither the publisher nor the author are engaged in design, legal, system operation, or other pro- fessional services. If any of these specific services are needed, a professional agency with the required specialization should be sought out. This book does no

4、t represent an endorsement of any particular product or procedure. The editors, authors, and pub- lisher make no claim as to the accuracy of the books contents, or their applicability to any particular circumstance. The editors, authors, and publisher accept no liability to any person for the inform

5、ation or advice provided in this book or for loss or damages incurred by any person as a result of reliance on its contents. Written permission to use the photographs in this document has been allowed as a courtesy by several water agencies across the United States. The photographs are not intended

6、to discredit any of the agencies or to present them in a negative perspective. AWWA Project Manager: Gay Porter De Nileon Technical Editor: Linda Bevard Production Editor: PerfecType, Nashville, TN Cover Design: Cheryl Armstrong Library of Congress Cataloging-in-Publication Data Morgan, Kenneth C.Ma

7、naging water main breaks : field guide / Kenneth C. Morgan.p. cm.Includes bibliographical references and index.ISBN 978-1-58321-860-01. Water-pipesMaintenance and repair. 2. Water leakage. 3. Pipeline failures. I. Title. TD495.M66 2012628.15dc232012011228 Print edition: ISBN-13: 9-781-58321-860-0ISB

8、N-10: 1-58321-860-2 Electronic edition ISBN: 9-781-61300-139-4 Printed in the United States of America. American Water Works Association 6666 W. Quincy Avenue Denver, Colorado 80235 www.awwa.org Managing Water Main Breaks.indd 4 5/3/2012 9:37:52 AMv Contents Preface. . . . . . . . . . . . . . . . .

9、. . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Acknowledgments xi Introduction .1 1 Causes of Water Main Breaks .3Natural Disasters .4Weather and Environmental Changes 4Ground and Soil Movement .5Defective and Aging Pipe Materials 6Defective or Improper Fittings and Connections 8Water Ha

10、mmer/Pressure Surges 9Corrosion 9Poor Design or Inspection . 14Improper Construction Practices . 15Traffic Loads and Insufficiently Deep Cover 16Unmarked or Mismarked Water Mains . 17Construction Damage . 18Questions to Consider 19 2 Impact of a Water Main Break .21Impact on the Provider . 22Impact

11、on the System and Staff 23Impact on the Customer . 25Impact on the Community . 27vi |managing water main breaksImpact on Other Utilities and Agencies 29Questions to Consider 29 3 How Water Main Breaks Are Identified .31Utility Employees 31Customers . 31Leak Detection/Audit Programs . 32Contractors 3

12、5Emergency Responders . 36Questions to Consider 37 4 Repair Site Safety .39Emergency Responders . 39Repairs by Water Utility Staff . 41Repairs by Contractors 42Safety Procedures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42Repair Equipment . 46Personal Protective Equipment 49

13、Care Around Other Utilities 50Preparation for Weather Extremes 51Questions to Consider 52 5 The Process of Repairing Water Main Breaks 53Prioritizing Repairs . 53Notifying Customers 54Notifying Other Utilities . 56Identifying Equipment, Materials, and Personnel . 57Pinpointing the Location of the Le

14、ak 57Excavating for Leak Exposure . 58Evaluating the Pipe Damage and Leak 59Chlorinating 65Providing and Compacting Proper Backfill Material . 66Performing Proper Site Restoration . 68Questions to Consider 68Contents |vii 6 Documenting Water Main Breaks .71Identifying and Compiling Critical Informat

15、ion 72Asset Management . 73Leak Reports . 75Responding to the Regulators . 76Questions to Consider 77 Appendix A: Pipe Repair Checklist .79 References and Bibliography .85 Index .89 About the Author 97ix Preface W ater main breaks are a primary cause of lost revenue and ser- vice for all water provi

16、ders. Some water leaks make the eve- ning news or the front page of the local newspaper. Others may go undetected until an unrelated excavation uncovers them or a mysterious soggy spot is identified and researched. Main breaks occur regularly in drinking water distribution sys- tems. Water providers

17、 experience about 240,000 water main breaks per year, according to a U.S. Environmental Protection Agency report about aging water infrastructure (USEPA 2007). Breaks interrupt ser- vice, often require costly repairs, pose the threat of contamination and the conveyance of waterborne disease, and cau

18、se customers to lose confidence in the water provider. The Report Card for Americas Infra- structure (ASCE 2009) gives the nations drinking water infrastructure a grade of D minus. Some of the major contributors to water main breaks are identified in this guidebook. One of the primary issues facing

19、water providers is the average age of the infrastructure and the importance of replace- ment. According to the USEPA (2002), “The useful design life of dis- tribution system components ranges from 6595 years.” The report further noted that the vast majority of the current underground water infrastru

20、cture in the United States was installed during the years just before through just after World War II, meaning the pipes will require replacement between the late 1990s and the 2030s. Assessment and Renewal of Water Distribution Systems (Grigg 2004) identifies the variables that predict pipe failure

21、s. The author provides related distribution system statistics and reviews the science behind x |managing water main breaks water main breaks. The Water Research Foundation is currently orga- nizing a National Mains Failure Database to document historic informa- tion on water main breaks from U.S. ut

22、ilities to be compared with data from Australia and the United Kingdom. Another major influence on the expected life of U.S. water infra- structure is the increase in the population. The U.S. population increased by approximately 159 percent in the last half of the twentieth century, and water usage

23、 increased by 207 percent, from 14 billion gal- lons to 43 billion gallons. This translates to a 20 percent increase in per capita use (average use per person) nationwide. The combination of an aging infrastructure experiencing an enormous increase in its origi- nally designed usage and the other fa

24、ctors presented in this guidebook directly contribute to the realities of water main breaks. This guidebook describes the causes of leaks, how to identify them, the effective use of information documented from main breaks, and, importantly, some cost-effective ways of making the repairs or managing

25、contractors who are performing the work. Kenneth C. Morgan, PE February 2012xi Acknowledgments T he author would like to thank the following people for their assis- tance, review, and contributions to this work: Charly Angadicheril, Assistant Water Director/Production, Fort Worth Water Department Jo

26、hn H. Bambei Jr., Chief of Engineering, Denver Water Mary Beckner, Assistant Water Distribution Superintendent, City of Phoenix Aimee Conroy, Water Services Superintendent, City of Phoenix Neil Grigg, Professor, Colorado State University Marcellus Jones, Distribution Systems Manager (retired), Las V

27、egas Valley Water District Greg Ramon, Former Assistant Director, City of Phoenix Marion Sanders, Training and Certification Manager, Charlotte Mecklenbur g Utilities1 Introduction N umerous books, manuals, reports, and articles include discus- sions about aspects of water main breaks. Some go into

28、detail, describing the science behind the breaks. Others provide effec- tive procedures for pipe repair and identify relevant products and services. In addition, several books describe the processes of leak detection and reporting and the value of these procedures. It is not the goal of this guidebo

29、ok to reiterate the work of oth- ers or to focus exclusively on the causes of breaks or on the repair process. The focus in this guidebook is to look at these breaks in jux- taposition with their impact on the system, the customers, and others. Seeing this larger picture can aid the water provider t

30、o better manage repair, rehabilitation, and replacement options. The information provided in this guidebook can be used for evalu- ating the overall impact of water main breaks and how to manage them as part of a utilitys responsibility to provide a quality product to customers. Often, utilities rep

31、air their leaky pipes without ever con- sidering the value of information they obtain during the excavation, investigation, and repair phases. Repairs are made without connecting the cause or occurrence of one leak to an adjacent leak until more damage or disruption of service pushes customers to th

32、e point of irrita- tion and lack of confidence in the utility. These scenarios and ways to manage them are also discussed in this guidebook. There is no one-size-fits-all solution to the repair of water main breaks, and this guidebook does not try to convey that. However the 2 |managing water main b

33、reaks right components must be in placethe right crew size, the correct training, and the proper equipment and materials. Each chapter concludes with a series of questions intended to help the water utility evaluate a specific issue, process, or program. These questions form guideposts that any util

34、ity desiring to provide the best service should consider. 3 1 Causes of Water Main Breaks M ain breaks are a reality for drinking water distribution systems. They interrupt service, often require costly repairs, pose the threat of contamination and the conveyance of waterborne disease, and cause cus

35、tomers to lose confidence in the water provider. Many things can cause water mains to leak or break. Natural disasters Ground and soil movement Defective and/or aging pipe Defective and/or improper fittings and connections Water hammer and pressure surges Internal or external corrosion Poor design o

36、r inspection of the distribution system Improper construction practices Traffic loads and insufficiently deep cover Unmarked or mismarked water mains4 |managing water main breaks Natural Disasters Natural disasters can disrupt water service by dislodging and/or over- whelming mains, fire hydrants, v

37、alves, and other distribution system components. Severe storms, floods, hurricanes, and tornadoes can inundate a service area so that the water utility cannot effectively pro- vide customers with a quality product and quality service. Some storms can destroy bridges and other structures to which dis

38、- tribution mains are often attached. Thus, the pipe may be pulled apart at the joints, bent, split, or even broken. Hurricane Katrina provided an extreme example of the negative impact of weather on a distribution system. The entire New Orleans infrastructure was inundated, which challenged the uti

39、litys ability to conventionally identify the location of system components. When con- sidering the possibility of such a severe incident, the water provider should develop plans to isolate critical portions of the system and restore them promptly as soon as conditions permit. Weather and Environment

40、al Changes The effects of freezing and thawing, extreme ground movement from flash floods and storms, or the ravages of hurricanes or tornados dam- age distribution systems. These natural weather phenomena should be accounted for during the design and construction phases before problems arise. The m

41、aintenance, operation, and restoration of these systems should also be part of the utilitys emergency response plans. In cold climates, it is a good practice to bury the water pipe and services deep enough that the possibility of freezing is reduced or eliminated. This can provide positive benefits,

42、 such as cooler water at the tap during the summer in warm environments. During extremely hot weather, a shallow depth of cover can result in water quality prob- lems and customer complaints. Distribution water pipe and services buried 3 to 4 feet deep can usually aid in a utilitys attempt to combat

43、 extreme temperatures. Deep installations may be more difficult to achieve in subsoil environments where rigid soil and rock exist. If there is a substantial difference between the temperature of the water flowing through the pipe and the temperature of the surrounding Causes of water main breaks |5

44、 soil and/or bedding material, minimal thermal expansion and contrac- tion can occur, possibly resulting in main breaks. Ground and Soil Movement Another problem for underground water mains is the movement of the soil surrounding the pipe. Breaks or leaks that have washed out bedding and fill materi

45、al, asphalt, or other surface treatment can cause extensive damage. This movement, which is often associated with The era of infrastructure replacement Like many of the roads, bridges, and other public assets on which the country relies, most of our buried drinking water infra- structure was built 5

46、0 or more years ago, in the post-World War II era of rapid demographic change and economic growth. In some older urban areas, many water mains have been in the ground for a century or longer. Given its age, it comes as no surprise that a large proportion of U.S. water infrastructure is approaching,

47、or has already reached, the end of its useful life. . . . Prudent planning for infrastructure renewal requires cred- ible, analysis-based estimates of where, when, and how much pipe replacement or expansion for growth is required. Utilities will continue efforts to manage the number of main breaks t

48、hat occur per mile of pipe rather than absorb increases in pipe failures. Utilities will strive to maintain cur- rent levels of service rather than allow increasing water service outages. Ideally, pipe replacement occurs at the end of a pipes “useful life”; that is, the point in time when replacemen

49、t or rehabilitation becomes less expensive in going forward than the costs of numerous unscheduled breaks and associated emergency repairs. Abridged Exceprt from Buried No Longer, Confronting Americas Infrastructure Challenge (AWWA 2012)6 |managing water main breaks flooding and storms or caused by insufficient compaction, can expose the pipe or cause it to rupture. Defective and Aging Pipe Materials Defective and aging pipe deteriorates more quickly than other pipe. Because of its inferior capability to convey water, compromised pipe is responsible