1、Copyright 2000 American Water Works Association. All rights reserved.Flexible-MembraneCovers and Linings forPotable-Water ReservoirsAWWA MANUAL M25Third EditionAmerican Water Works AssociationFOUNDED1881Copyright 2000 American Water Works Association. All rights reserved.MANUAL OF WATER SUPPLY PRACT
2、ICESM25, Third EditionFlexible-Membrane Covers and Linings for Potable-Water ReservoirsCopyright 1987, 1996, 2000 American Water Works AssociationAll rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means,electronic or mechanical, including photocop
3、y, recording, or any information or retrieval system, except in the formof brief excerpts or quotations for review purposes, without the written permission of the publisher.Project manager and copy editor: David TalleyProduction editor: Carol MaginLibrary of Congress Cataloging-in-Publication DataFl
4、exible-membrane covers and linings for potable water reservoirs.-3rd ed.p. cm. - (AWWA manual ; M25)Includes bibliographical references and index.ISBN 1-58321-070-91. Reservoirs-Linings-Handbooks, manuals, etc. 2. Membranes (Technology)-Handbooks, manuals, etc. I. American Water Works Association. I
5、I.Series.TD491 .A49 no. M25 2000TD395628.1 s-dc21628.132 00-044161Printed in the United States of AmericaAmerican Water Works Association6666 West Quincy AvenueDenver, CO 80235Printed on recycled paperISBN: 1-58321-070-9Copyright 2000 American Water Works Association. All rights reserved.ContentsLis
6、t of Figures, vAcknowledgments, viiChapter 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Purpose and Scope, 1Description of Facilities, 1Advantages and Disadvantages, 2Permeation, 2Definitions, 2Survey of Existing Facilities, 6Chapter 2 Design
7、and Installation of Flexible-Membrane Floating Covers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Floating-Cover Design, 7Floating-Cover Installation, 14Chapter 3 Operation, Inspection, and Maintenance Guidelines for Floating Covers . . . . . . . . .
8、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17General, 17Operation, 18Maintenance, 21Chapter 4 Design and Installation of Flexible-Membrane Linings . . . . . 23Lining Design, 23Lining Installation, 27Chapter 5 Operation and Maintenance Guidelines for Linings . . . . . . . . 31O
9、peration, 31Maintenance, 33Bibliography, 35Index, 37List of AWWA Manuals, 39iiiCopyright 2000 American Water Works Association. All rights reserved.This page intentionally blank.Copyright 2000 American Water Works Association. All rights reserved.vFigures1-1 Cross sections of a typical weighted-sump
10、 floating-cover system, shownfull and empty, 31-2 Mechanically tensioned floating cover, 41-3 Cross sections of Fabritank cover system, shown full and empty, 51-4 Fabritank installation for a 1-mil-gal (3.785-ML) storage facility at San Jose, Calif., 52-1 Floating cover installed in 1978 on a 25-mil
11、-gal (94.6-ML) reservoir atRiverside, Calif., 82-2 Floating covers installed in 1981 on 4-mil-gal (15.1-ML) and 17-mil-gal(64.3-ML) reservoirs at Manchester, N.H., 82-3 Floating covers installed in 1991 on two 4-mil-gal (15.1-ML) reservoirs atMeriden, Conn., 92-4 Floating cover installed in 1989 on
12、an 83-mil-gal (314.2-ML) reservoir inEagle Rock, Calif., 92-5 Seaming polypropylene with a self-propelled hot-air welder, 152-6 Installing a polypropylene patch with an extrusion welder, 153-1 Surface-water removal system used by Metropolitan Water District of Southern California, 183-2 Surface-wate
13、r removal system used by Manchester (N.H.) Water Works, 193-3 Sample inspection and maintenance schedule for floating covers, 204-1 Installation of a flexible-membrane lining in a reservoir in Syracuse, N.Y., 28Copyright 2000 American Water Works Association. All rights reserved.This page intentiona
14、lly blank.Copyright 2000 American Water Works Association. All rights reserved.viiAcknowledgmentsThis manual was prepared by the AWWA Standards Committee on Flexible ReservoirCovers and Linings for Potable Water Storage. The membership of the committee at thetime it approved this manual was:David Ki
15、ttredge, ChairLarry R. Schader, SecretaryConsumer MembersD.A. Hilts, Metropolitan Water District of Southern California,Los Angeles, Calif. (AWWA)J.J. Morris, Camden County Department of Public Works,Lindenwold, N.J. (AWWA)G.A. Radek, Metropolitan Utilities District, Omaha, Neb. (AWWA)R.C. Spradling
16、,*Metropolitan Water District of Southern California,LaVerne, Calif. (AWWA)P.E. Tomes, Cincinnati Water Works, Cincinnati, Ohio (AWWA)G.H. Yamamoto, California Department of Health Services,Los Angeles, Calif. (AWWA)General Interest MembersPhilip Gatsoulis, Senior Consultant, San Marino, Calif. (AWW
17、A)D.H. Gerber, Consultant, Hollister, Calif. (AWWA)D.F. Greiner, NSF International, Ann Arbor, Mich. (NSF)David Kittredge, Dufresne-Henry Inc., Manchester, N.H. (NEWWA)J.L. Lane,Council Liaison, Missouri Department of Natural Resources, Jefferson City, Mo. (AWWA)J.S. Wailes,Standards Engineer Liaiso
18、n, AWWA, Denver, Colo. (AWWA)Producer MembersG.G. Emerson, Serrot Corporation, Huntington Beach, Calif. (AWWA)D.J. McCullough, Watersaver Company, Denver, Colo. (AWWA)L.R. Schader, JPS Elastomerics Corp., Salem, Ore. (AWWA)* Alternate Liaison, nonvotingCopyright 2000 American Water Works Association
19、. All rights reserved.This page intentionally blank.Chapter 1IntroductionPURPOSE AND SCOPEThis manual is intended to serve as a technical reference guide in designing,installing, operating, and maintaining reservoirs using flexible-membrane materialsfor linings and floating covers. Source informatio
20、n was gathered by reviewing and col-lecting the experience of designers, manufacturers, and owners of flexible-membraneproducts that were introduced to the water industry in the early 1950s.This manual is not intended to be a design handbook or the equivalent ofan AWWA standard. Rather, it should se
21、rve as a technical reference document to beused in conjunction with AWWA D130, Standard for Flexible-Membrane-Lining andFloating-Cover Materials for Potable Water Storage, which was first approved for pub-lication in January 1987.Information in this manual may not apply to all types of installations
22、 or materi-als. In applying specific recommendations, the user must assume responsibility foraccommodating a specific set of conditions.DESCRIPTION OF FACILITIESFlexible-membrane linings and floating covers can be incorporated into many typesof water-storage facilities, both new construction and reh
23、abilitated structures. Sometypical examples of facilities include An earthen reservoir for storage of untreated or raw water. A flexiblelining used in this type of installation is normally intended to minimize waterlosses due to seepage. In arid regions, a flexible-floating cover might beinstalled t
24、o reduce water loss due to evaporation, as well. An earthen reservoir for storage of potable water. Such a facilitymight be located at a water treatment plant or within a distribution system.AWWA MANUAL M251Copyright 2000 American Water Works Association. All rights reserved.Normally, the structure
25、would incorporate both lining and floating cover toreduce water losses and to protect the treated water from contamination. A covered storage facility that has developed an excessive leakagecondition. This type of structure might be constructed of steel, concrete, oranother material, or it might be
26、asphalt-lined. Normally, a lining would beinstalled without a floating cover to reduce leakage and protect the storedwater from outside contamination. An uncovered storage facility requiring protection from contamination.A flexible floating cover can quite often be used to meet these requirements.Ma
27、ny large, open reservoirs have been covered in this manner.ADVANTAGES AND DISADVANTAGESThe principal advantages of flexible linings and floating covers are low capital cost,reduction of algal growth, reduction of chlorine demand, prevention of airborne andgroundwater contamination, and prevention of
28、 evaporation and seepage losses.The principal disadvantages of flexible linings and covers are susceptibility todamage by ice action and vandalism, shorter life expectancy than rigid cover instal-lations, and the need for regularly scheduled maintenance to inspect the membraneand system integrity, r
29、emove surface water and debris, and make repairs.PERMEATIONSelection of materials is critical for water-storage facilities and distribution piping inlocations where the reservoir materials and/or pipe will likely be exposed to significantconcentrations of pollutants composed of low-molecular-weight
30、petroleum products ororganic solvents and their vapors. Research has documented a potential for such com-pounds to permeate through plastic pipe materials such as polyethylene, polybutylene,polyvinyl chloride (PVC), and asbestoscement and through elastomers such as thoseused in jointing gaskets and
31、packing glands. If a reservoir must be located in, or a waterpipe must pass through, an area subject to such contamination, consult with the man-ufacturer regarding permeation of pipe walls, jointing materials, reservoir membranes,and similar structures before selecting materials for use in that are
32、a.DEFINITIONSFor the purpose of this manual, the following definitions apply:Access features: Access hatches/pathways, perimeter access vaults, andperimeter canopies incorporated into a floating reservoir cover to allow access by per-sonnel under the cover while it is floating or inflated.Air vents:
33、 Vents provided only as required to release entrained air that enters thereservoir with the water and subsequently separates and bubbles to the surface beneaththe floating cover. Vents are also used to prevent formation of vacuum in areas wherewater exits the reservoir (outlets, overflow drains, etc
34、.). Vents can have a negative effecton wind resistance of floating reservoir covers, so their use should be minimized.2 FLEXIBLE-MEMBRANE COVERS AND LININGSCopyright 2000 American Water Works Association. All rights reserved. Closed-cell float: (See Floats.)Coating: A film built up through successiv
35、e applications of an appropriate dis-persion or solution system to achieve a specific dry-film thickness. Generally, coatingsare applied to steel tanks for the purpose of protecting the steel against corrosion.Cover: (See Flexible cover.)Cut-and-fill reservoir: A water-holding facility constructed b
36、y excavating acentral portion and, normally, forming the excavated earth as fill material into anembankment that increases the capacity of the reservoir while avoiding costs of dis-posal for the excavated material.Earthen reservoir: (See Cut-and-fill reservoir.)Fabricator: The person, company, or or
37、ganization that joins sheets of floatingmembrane material into large panels in a fabrication plant for delivery to the job sitefor installation.Flexible baffles: Curtains of flexible membrane (usually the same material as thecover membrane) attached to the cover and extending vertically to the floor
38、 of the reservoirin geometrically prescribed locations. Flexible baffles direct the flow of water throughout thearea of the reservoir to control the contact/residence time of disinfected water.Flexible floating cover: A continuous, flexible, impervious, weather-resistantmembrane material that floats
39、 on the surface of a water reservoir to function as acover system. Three types of flexible floating covers are recognized: (1) a floating sys-tem, generally with a wind-stabilizing, closed-cell float grid system and weightedsump (see Figure 1-1); (2) a post-tensioned system, mechanically stabilized
40、or ten-sioned (see Figure 1-2); (3) an inflated system (not discussed in this manual); and (4)3INTRODUCTIONCopyright 2000 American Water Works Association. All rights reserved.Source: Metropolitan Water District of Southern California.Figure 1-1 Cross sections of a typical weighted-sump floating-cov
41、er system, shown full and emptySchematic of full reservoir (not to scale)Schematic of empty reservoir (not to scale)a nontensioned cover (not discussed in this manual, and no longer considered state-of-the-art technology).Flexible membrane: Any of a number of continuous, flexible, impermeablemembran
42、es, usually ranging in thickness between 0.036 in. (0.91 mm) and 0.060 in.(1.52 mm), which may be fabricated into large panels for final assembly in the field.The membrane may be nonreinforced or scrim reinforced, depending on the physicalrequirements of the application. Three types of flexible memb
43、rane materials are gen-erally seen: (1) plastic (thermoplastic), (2) cured elastomer, and (3) uncured elastomer(thermoplastic elastomer).Flexible tank: A bag-like facility for holding liquid formed by sealing the edgesof two appropriately shaped flexible membranes and provided with inlet, outlet, an
44、doverflow pipe connections. These installations, most commonly called “embankment-supported flexible tanks,” are usually factory assembled, which precludes tank capac-ities larger than approximately 1 mil gal (3.785 ML). Tanks that meet the generalguidelines of this manual and AWWA D130 could be con
45、sidered suitable for installa-tion, provided special design details and installation and construction methods areimplemented as provided by the manufacturer. (See Figures 1-3 and 1-4.)Floats: Closed-cell, semirigid foam members, usually encased in the same typeof membrane material as the floating co
46、ver and permanently joined to it. A typicalfloat cross section is 4 in. by 12 in. (100 mm by 300 mm); typical density is 2.2 pcf(35.2 g/L). Floats are usually required for wind stabilization, to facilitate rainwaterremoval, and as emergency buoyancy to prevent sinking of the cover in the event ofa p
47、uncture.Geotextile: A permeable synthetic fabric used to protect a flexible liner fromdamage due to rough or uneven surfaces and to promote venting of gases.Inflation features: Specific design features to allow a floating reservoir coverto be conveniently, safely, and temporarily inflated and access
48、ed for reservoir inspec-tion, cleaning, and maintenance.Installer (installing contractor): The person, company, or organization thatinstalls the flexible-membrane liner or floating cover in the field.4 FLEXIBLE-MEMBRANE COVERS AND LININGSCopyright 2000 American Water Works Association. All rights re
49、served.Source: C.W. Neal Corporation.Figure 1-2 Mechanically tensioned floating coverCopyright 2000 American Water Works Association. All rights reserved.5INTRODUCTIONSource: AMFUEL.Figure 1-3 Cross sections of Fabritank cover system, shown full and emptySource: AMFUEL.Figure 1-4 Fabritank installation for a 1-mil-gal (3.785-ML) storage facility at San Jose, Calif.Copyright 2000 American Water Works Association. All rights reserved.6 FLEXIBLE-MEMBRANE COVERS AND LININGSLining:
