AWWA Disinfection C652-02.pdf

AMERICAN WATER WORKS ASSOCIATION

6666 West Quincy Avenue, Denver, Colorado 80235 www.awwa.org

R

American Water Works Association

ANSI/AWWA C652-02

(Revision of ANSI/AWWA C652-92)

AWWA STANDARD

FOR

DISINFECTION OF WATER-STORAGE

FACILITIES

Effective date: Aug. 1, 2002.

First edition approved by AWWA Board of Directors June 15, 1980.

This edition approved Jan. 20, 2002.

Approved by American National Standards Institute Inc., May 21, 2002.

Copyright © 2002 American Water Works Association ii

AWWA Standard

This document is an American Water Works Association (AWWA) standard. It is not a specification.

AWWA standards describe minimum requirements and do not contain all of the engineering and administrative information normally contained in specifications. The AWWA standards usually contain options that must be evaluated by the user of the standard. Until each optional feature is specified by the user, the product or service is not fully defined. AWWA publication of a standard does not constitute endorsement of any product or product type, nor does AWWA test, certify, or approve any product. The use of AWWA standards is entirely voluntary. AWWA standards are intended to represent a consensus of the water supply industry that the product described will provide satisfactory service. When AWWA revises or withdraws this standard, an official notice of action will be placed on the first page of the classified advertising section of Journal AWWA. The action becomes effective on the first day of the month following the month of Journal AWWA publication of the official notice.

American National Standard

An American National Standard implies a consensus of those substantially concerned with its scope and provisions. An American National Standard is intended as a guide to aid the manufacturer, the consumer, and the general public. The existence of an American National Standard does not in any respect preclude anyone, whether that person has approved the standard or not, from manufactur-ing, marketing, purchasing, or using products, processes, or procedures not conforming to the standard. American National Standards are subject to periodic review, and users are cautioned to obtain the latest editions. Producers of goods made in conformity with an American National Standard are encouraged to state on their own responsibility in advertising and promotional materials or on tags or labels that the goods are produced in conformity with particular American National Standards.

CAUTION NOTICE: The American National Standards Institute (ANSI) approval date on the front cover of this standard indicates completion of the ANSI approval process. This American National Standard may be revised or withdrawn at any time. ANSI procedures require that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of publication.

Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute, 25 W. 43rd St., Fourth Floor, New York, NY 10036; (212) 642-4900.

All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, elec-tronic or mechanical, including photocopy, recording, or any information or retrieval system, except in the form of brief excerpts or quotations for review purposes, without the written permission of the publisher.

Copyright © 2002 American Water Works Association Printed in USA iii

Committee Personnel

The AWWA Standards Committee on Disinfection of Facilities which reviewed and approved this standard, had the following personnel at the time of approval:

M.S. Solomon, Chair

Consumer Members

J.E. French, Belleair Bluffs, Fla. (AWWA)

L.A. Hensley, GDS Associates Inc., Marietta, Ga. (AWWA)

R.C. Lorenz, Westerville Water Plant, Westerville, Ohio (AWWA)

T.W.D. MacDonald, Cambridge Water Department, North Andover, Mass. (AWWA)

P.M. Marchand, Pawtucket Water Supply Board, Pawtucket, R.I. (NEWWA)

E.D. Schwartz, Elizabethtown Water Company, Plainfield, N.J. (AWWA)

C.H. Smith, Savoy, Ill. (AWWA)

J.L. Stapf, City of Wyoming Water Department, Wyoming, Mich. (AWWA)

General Interest Members

K.C. Choquettes, Iowa Department of Public Health, Des Moines, Iowa (AWWA)

D.J. Hartman, Standards Council Liaison, Cincinnatti, Ohio (AWWA)

C.B. Hagar, Carollo Engineers, Phoenix, Ariz. (AWWA)

T. Lambert, Florida Department of Environmental Protection, Orlando, Fla. (AWWA)

M.S. Solomon, Winzler & Kelly Consulting Engineers, Santa Rosa, Calif. (AWWA)

T.W. Walker, New York State Department of Health, Victor, N.Y. (AWWA)

M.L. Wentink, Nebraska Department of Health, North Platte, Neb. (AWWA)

J.H. Wilber,* Standards Engineer Liaison, AWWA, Denver, Colo. (AWWA)

Producer Members

W.B. Huebner, The Capital Controls Group, Colmar, Pa. (AWWA)

M.L. Johnsen, Johnsen Corrosion Engineering, Greenwood, Neb. (AWWA)

*Liaison, nonvoting

This page intentionally blank.

v

Contents

All AWWA standards follow the general format indicated subsequently. Some variations from this format may be found in a particular standard.

SEC. PAGE SEC. PAGE

Foreword

I Introduction.......................................... vii

I.A Background........................................... vii

I.B History .................................................. vii

I.C Acceptance ............................................ vii

II Special Issues ...................................... viii

II.A Information on Application of This

Standard............................................. viii

III Use of This Standard............................. x

III.A Purchaser Options and Alternatives ... xi

III.B Modification to Standard...................... xi

IV Major Revisions..................................... xi

V Comments.............................................. xi

Standard

1 General

1.1 Scope

1.2 Purpose

1.3 Application

2 References

3 Definitions

4 Requirements

4.1 Materials

4.2 Forms of Chlorine for Disinfection

4.3 Methods of Chlorination

4.4 Disinfection Procedures When

Conducting Underwater Inspection of Potable-Water-Storage

Facilities

5 Verification

5.1 Bacteriological Sampling and

Testing

6 Delivery

Appendixes

A Chlorine Residual Testing

B Chlorine Dosages

C Disposal of Heavily Chlorinated

Water

Tables

B.1 Amounts of Chemicals Required to

Give Various Chlorine Concentrations in 100,000 gal (378.5 m3) of Water

B.2 Amounts of Chemicals Required to

Give Various Chlorine Concentrations of 200 mg/L in Various Volumes of Water

C.1 Amounts of Chemicals Required to

Neutralize Various Residual Chlorine

Concentrations in 100,000 gal

(378.5 m3) of Water vii

Foreword

This foreword is for information only and is not a part of AWWA C652.

I. Introduction.

I.A. Background. This standard describes methods of disinfecting water storage tanks. The disinfecting agents discussed in this standard are chlorine solutions, and several combinations of free chlorine residual and contact time (CT) are provided. The chlorine solutions may be derived from liquid chlorine (Cl2), calcium hypochlorite (Ca(OCl)2), or sodium hypochlorite (NaOCl).

I.B. History. This standard was first approved on June 15, 1980, under the designation AWWA D105, Standard for Disinfection of Water Storage Facilities. The

1980 edition was developed from information originally contained in AWWA D102-64, modified to include disinfection of water-storage facilities constructed of steel or other materials. The standard was redesignated AWWA C652 with the 1986 edition. It was revised in 1992. This edition was approved on Jan. 20, 2002.

I.C. Acceptance. In May 1985, the US Environmental Protection Agency

(USEPA) entered into a cooperative agreement with a consortium led by NSF

International (NSF) to develop voluntary third-party consensus standards and a certification program for all direct and indirect drinking water additives. Other members of the consortium included the American Water Works Association

Research Foundation (AWWARF) and the Conference of State Health and Environ-mental Managers (COSHEM). The American Water Works Association (AWWA) and the Association of State Drinking Water Administrators (ASDWA) joined later.

In the United States, authority to regulate products for use in, or in contact with, drinking water rests with individual states.* Local agencies may choose to impose requirements more stringent than those required by the state. To evaluate the health effects of products and drinking water additives from such products, state and local agencies may use various references, including

1. An advisory program formerly administered by USEPA, Office of Drinking

Water, discontinued on Apr. 7, 1990.

2. Specific policies of the state or local agency.

*Persons in Canada, Mexico, and non-North American countries should contact the appropriate authority having jurisdiction.

viii

3. Two standards developed under the direction of NSF, ANSI*/NSF† 60, Drinking Water Treatment Chemicals—Health Effects, and ANSI/NSF 61, Drinking

Water System Components—Health Effects.

4. Other references, including AWWA standards, Food Chemicals Codex, Water Chemicals Codex,‡ and other standards considered appropriate by the state or local agency.

Various certification organizations may be involved in certifying products in accordance with ANSI/NSF 60. Individual states or local agencies have authority to accept or accredit certification organizations within their jurisdiction. Accreditation of certification organizations may vary from jurisdiction to jurisdiction.

Annex A, “Toxicology Review and Evaluation Procedures,” to ANSI/NSF 60 does not stipulate a maximum allowable level (MAL) of a contaminant for substances not regulated by a USEPA final maximum contaminant level (MCL). The

MALs of an unspecified list of “unregulated contaminants” are based on toxicity testing guidelines (noncarcinogens) and risk characterization methodology (carcino-gens). Use of Annex A procedures may not always be identical, depending on the certifier.

AWWA C652 does not address additives requirements. Thus, users of this standard should consult the appropriate state or local agency having jurisdiction in order to

1. Determine additives requirements, including applicable standards.

2. Determine the status of certifications by all parties offering to certify products for contact with, or treatment of, drinking water.

3. Determine current information on product certification.

II. Special Issues.

II.A. Information on Application of This Standard. Utilities are increasingly focusing on water storage reservoir management and maintenance as part of preserving distribution system water quality. As more frequent inspections and cleaning of reservoirs are required, utilities are turning to methods, which minimize downtime and wasted water. Utilities are utilizing inspection methods such as divers, *American National Standards Institute, 25 W. 43rd St., Fourth Floor, New York, NY 10036.

†NSF International, 789 N. Dixboro Rd., Ann Arbor, MI 48105.

‡Both publications available from National Academy of Sciences, 2102 Constitution Ave.

N.W., Washington, DC 20418.

ix float down, remotely operated vehicles for both inspection and sediment removal.

Sec. 4.4 of this standard describes the disinfection procedures and operational considerations for conducting in-service inspection and cleaning in potable-water-storage facilities. Originally this standard addressed inspection of storage tanks by diving but has been expanded to address all forms of inspection and cleaning that are performed while the tanks are full of water.

It should be noted that any underwater retrieval of remotely operated vehicles with divers must be performed in accordance with all aspects of this standard.

Although, Sec. 4.4 specifically addresses water quality protection, the diving subcommittee felt it was very important to communicate the critical aspects of contractor safety, which should be incorporated into any project of this type. Utilities must be aware that it is their responsibility to determine if contractors working on their property are following proper OSHA procedures. When selecting a contractor to perform this type of work, it is essential to evaluate their experience, safety procedures, and methods. Each bidder should be willing to meet the minimums set by this standard for safe performance of the work.

This standard includes references to pertinent OSHA regulations.

It should be recognized that there are specific technical skills a utility should look for when considering a firm for this type of work:

• Qualifications for conducting in-service operations in compliance with

OSHA

• Qualifications for inspecting and evaluating steel/concrete/wood or mem-brane-covered reservoirs

• Resumes for those specific personnel who will perform underwater inspection

Sec. 4.4 does not address the following items, each of which must be specified by the purchaser:

1. The type of inspection to be performed (structural, coating, bottom sediment, cathodic protection, bacteriological, and so forth).

2. The technical requirements of the inspection.

For additional guidance:

Refer to AWWA M42 Manual of Water Supply Practices Steel Water-Storage

Tanks.

Sec. 4.4 does not attempt to rewrite existing safety standards and relies on the existing applicable OSHA Standards, including but not limited to x

OSHA, 29 CFR, Subpart T Commercial Diving Operations 1910.401 through 1910.441

OSHA, 29 CFR, Permit Required Confined Spaces, 1910.146

III. Use of This Standard. This standard describes methods of disinfecting water-storage facilities that are newly constructed, have been entered for construc-tion or inspection purposes, or that continue to show the presence of coliform bacteria during normal operation. In addition, the standard defines disinfection procedures for underwater inspections because water utilities increasingly are employing divers to conduct underwater inspections of on-line potable-water-storage facilities to minimize water loss and downtime normally associated with necessary maintenance inspections. The standard does not describe the type and technical requirements of underwater inspection or the required skill level of the diving inspector.

A storage facility is defined as a reservoir from which water, without further treatment other than booster disinfection, is supplied directly to the distribution piping system for domestic use. From a practical standpoint, this standard applies to the disinfection of covered storage facilities constructed of steel, concrete, or materials that would provide a similar structure from a water quality standpoint.

Because wood may support the growth of coliform bacteria, it is recommended that any submerged wood surface (columns, baffles, and so forth) be coated with epoxy or other durable, effectively impermeable paint or coating approved for domestic water use.

Parts of this standard may be applicable to the disinfection of large, finished-water, open storage reservoirs, such as reservoirs formed by concrete or earth dams, but these applications are incidental, and this standard is not intended to cover those kinds of storage facilities.

Three methods of chlorinating storage facilities are described in this standard.

Each utility should decide which method is most suitable for a given situation. In selecting the method to be used, the utility should consider the availability of materials and equipment for disinfection, the training of personnel who will perform the disinfection, and safety. For example, gas chlorination should be used only when properly designed and constructed equipment is available; makeshift equipment is not acceptable when liquid-chlorine cylinders are used. Spray equipment should be used inside the storage facility only when thorough ventilation is assured or when appropriate protection is provided using canister-type gas masks or self-contained breathing units. If a chlorination method is selected that requires the draining of a xi storage facility in order to dispose of highly chlorinated water, then thorough consideration should be given to the effect on the receiving environment. If there is any question as to whether a chlorinated-waste discharge may cause damage to fish life, plant life, physical installations, or other downstream water uses of any type, then an adequate amount of a reducing agent should be applied to the discharged water in order to thoroughly neutralize the chlorine residual.

III.A. Purchaser Options and Alternatives. This standard is written as though the work will be done by the purchaser’s personnel. If the purchaser is contracting for the work to be done, appropriate provisions should be included in the contract agreement to ensure that the constructor is specifically instructed as to his responsibilities. At the least, the purchaser should specify the following:

1. Standard used—that is, AWWA C652, Standard for Disinfection of

Water-Storage Facilities, of latest edition.

2. Method of disinfection to be used.

3. Any required disposal and precautions to be taken in disposing of chlorinated water in the storage facility.

4. Bacteriological testing and method to be used.

5. Redisinfection procedure if required.

III.B. Modification to Standard. Any modification of the provisions, defini-tions, or terminology in this standard must be provided in the purchaser’s specifications.

IV. Major Revisions. Major changes made in this revision of AWWA C652 are as follows:

1. Sec. 4.4, Disinfection Procedures When Conducting Underwater Inspection of Potable-Water-Storage Facilities, was modified.

V. Comments. If you have any comments or questions about this standard, please call the AWWA Volunteer & Technical Support group, (303) 794-7711 ext.

6283, FAX (303) 795-7603, or write to the group at 6666 W. Quincy Ave., Denver, CO

80235.

American Water Works Association

ANSI/AWWA C652-02

(Revision of ANSI/AWWA C652-92)

AWWA STANDARD FOR

DISINFECTION OF WATER-STORAGE

FACILITIES

SECTION 1: GENERAL

Sec. 1.1 Scope

This standard for disinfection of water-storage facilities describes materials, facility preparation, application of disinfectant to interior surfaces of facilities, and sampling and testing for the presence of coliform bacteria. The standard also includes disinfection procedures for underwater inspection of on-line, potable-water-storage facilities but does not describe the technical aspects of underwater inspection. All new storage facilities shall be disinfected before they are placed in service. All storage facilities taken out of service for inspecting, repairing, painting, cleaning, or other activity that might lead to contamination of water shall be disinfected before they are returned to service.

Sec. 1.2 Purpose

The purpose of this standard is to define the minimum requirements for the disinfection of water storage facilities, including the preparation of water storage facilities, application of chlorine, procedures for disinfecting underwater inspection equipment, and sampling and testing for the presence of coliform bacteria.

Sec. 1.3 Application

This standard can be referenced in specifications for the disinfection of water storage facilities and can be used as a guide for the preparation of water storage

2 AWWA C652-02

facilities, application of chlorine, disinfection procedures to be used during underwater inspections, and testing for the presence of coliform bacteria. The stipulations of this standard apply when this document has been referenced and then only to the disinfection of water storage facilities.

SECTION 2: REFERENCES

This standard references the following documents. In their latest edition, they form a part of this standard to the extent specified within the standard. In case of any conflict, the requirements of this standard shall prevail.

ANSI*/AWWA B300—Hypochlorites.

ANSI/AWWA B301—Liquid Chlorine.

Standard Methods for the Examination of Water and Wastewater. APHA,†

AWWA, and WEF.‡ Washington, D.C. (20th ed., 1998).

Additional materials relating to activity according to this standard include the following:

Chlorine Manual—Chlorine Institute Inc.§

Introduction to Water Treatment. WSO Series, Vol. 2. AWWA, Denver (1994).

Material safety data sheets for forms of chlorine used (provided by suppliers).

Safety Practice for Water Utilities. AWWA Manual M3. AWWA, Denver (2002).

Water Chlorination Principles and Practices. AWWA Manual M20. AWWA, Denver (1973).

Water Quality and Treatment. AWWA, Denver (5th ed.).

SECTION 3: DEFINITIONS

1. Constructor: The party that provides the work and materials for placement and installation.

*American National Standards Institute, 25 W. 43rd St., Fourth Floor, New York, NY 10036.

†American Public Health Association, 800 I St., N.W., Washington, DC 20001-3710.

‡Water Environment Federation, 601 Wythe St., Alexandria, VA 22314.

§Chlorine Institute Inc., 2001 L St. N.W., Suite 506, Washington, DC 20036-4919.

DISINFECTION OF WATER-STORAGE FACILITIES 3

SECTION 4: REQUIREMENTS

Sec. 4.1 Materials and Cleaning

4.1.1 Materials entering tank. All scaffolding, planks, tools, rags, and other materials not part of the structural or operating facilities of the tank shall be removed. Then the surfaces of the walls, floor, and operating facilities of the storage facility shall be cleaned thoroughly using a high-pressure water jet, sweeping, scrubbing, or equally effective means. All water, dirt, and foreign material accumulated in this cleaning operation shall be discharged from the storage facility or otherwise removed.

4.1.2 Other materials. Following the cleaning operation, the vent screen, overflow screen, and any other screened openings shall be checked and put in satisfactory condition to prevent birds, insects, and other possible contaminants from entering the facility. Any material required to be in the operating storage facility after the cleaning procedure has been completed shall be clean and sanitary when placed in the facility. In these instances, care shall be taken to minimize the introduction of dirt or other foreign material. (For example, placing a layer of limestone granules on the unpainted bottom of the storage facility to prevent corrosion.)

Sec. 4.2 Forms of Chlorine for Disinfection

The forms of chlorine that may be used in the disinfecting operations are liquid chlorine, sodium hypochlorite solution, and calcium hypochlorite granules or tablets.

4.2.1 Liquid chlorine. Liquid chlorine conforming to ANSI/AWWA B301 con-tains 100 percent available chlorine and is packaged in steel containers usually of

100-lb, 150-lb, or 1-ton (45.4-kg, 68.0-kg, or 907.2-kg) net chlorine weight. Liquid chlorine shall be used only (1) in combination with appropriate gas-flow chlorinators and ejectors to provide a controlled high-concentration solution feed to the water to be chlorinated; (2) under the direct supervision of a person who is familiar with chlorine’s physiological, chemical, and physical properties, and who is trained and equipped to handle any emergency that may arise; and (3) when appropriate safety practices are observed to protect working personnel and the public.

4.2.2 Sodium hypochlorite. Sodium hypochlorite conforming to ANSI/AWWA

B300 is available in liquid form in glass, rubber-lined, or plastic containers typically ranging in size from 1 qt (0.95 L) to 5 gal (18.92 L). Containers of 30 gal (113.6 L) or

4 AWWA C652-02

larger may be available in some areas. Sodium hypochlorite contains approximately

5 percent to 15 percent available chlorine by volume, and care must be taken to control storage conditions and length of storage to minimize its deterioration.

4.2.3 Calcium hypochlorite. Calcium hypochlorite conforming to ANSI/

AWWA B300 is available in granular form or in small tablets and contains approximately 65 percent available chlorine by weight. The material should be stored in a cool, dry, dark environment to minimize its deterioration.

Sec. 4.3 Methods of Chlorination

Three methods of chlorination are explained in this standard. Typically, only one method will be used for a given storage-facility disinfection, but combinations of the methods may be used. The three methods are (1) chlorination of the full storage facility such that, at the end of the appropriate retention period, the water will have a free chlorine residual of not less than 10 mg/L; (2) spraying or painting of all storage facility water-contact surfaces with a solution of 200-mg/L available chlorine;

and (3) a two-step process of chlorinating the bottom portion of the storage facility with 50-mg/L available chlorine followed by filling to overflow and maintaining a free chlorine residual of at least 2 mg/L for 24 hr.

4.3.1 Chlorination method 1. The water-storage facility shall be filled to the overflow level with potable water to which enough chlorine is added to provide a free chlorine residual in the full facility of not less than 10 mg/L at the end of the appropriate 6-hr or 24-hr period, as described in Sec. 4.3.1.4. The chlorine, either as calcium hypochlorite, sodium hypochlorite, or liquid chlorine, shall be introduced into the water as described hereafter.

4.3.1.1 Liquid-chlorine use. Liquid chlorine shall be introduced into the water filling the storage facility in such a way as to give a uniform chlorine concentration during the entire filling operation. Portable chlorination equipment shall be carefully operated and shall include a liquid-chlorine cylinder, gas-flow chlorinator, chlorine ejector, safety equipment, and an appropriate solution tube to inject the high-concen-tration chlorine solution into the filling water. The solution tube shall be inserted through an appropriate valve located on the inlet pipe and near the storage facility such that the chlorine solution will mix readily with the inflowing water.

4.3.1.2 Sodium hypochlorite use. Sodium hypochlorite shall be added to the water entering the storage facility by means of a chemical-feed pump or shall be applied by hand-pouring into the storage facility and allowing the inflowing water to provide the desired mixing.

DISINFECTION OF WATER-STORAGE FACILITIES 5

4.3.1.2.1 When a chemical-feed pump is used, the concentrated chlorine solution shall be pumped through an appropriate solution tube so as to inject the high-concentration chlorine solution at a rate that will give a uniform chlorine concentration in the filling water. The solution tube shall be inserted through an appropriate valve located on the inlet pipe and near the storage facility, or through an appropriate valve located on the storage facility such that the chlorine solution will mix readily with the filling water.

4.3.1.2.2 When the sodium hypochlorite is poured into the storage facility, the filling of the storage facility shall begin immediately thereafter or as soon as any removed manhole covers can be closed. The sodium hypochlorite may be poured through the cleanout or inspection manhole in the lower course or level of the storage facility, in the riser pipe of an elevated tank, or through the roof manhole. The sodium hypochlorite shall be poured into the water in the storage facility when the water is not more than 3 ft (0.9 m) in depth, nor less than 1 ft (0.3 m) in depth or as close thereto as manhole locations permit.

4.3.1.3 Calcium hypochlorite use. Calcium hypochlorite granules or tablets broken or crushed to sizes not larger than 1/4-in. (6.4-mm) maximum dimension may be poured or carried into the storage facility through the cleanout or inspection manhole in the lower course or level of the storage facility, into the riser pipe of an elevated tank, or through the roof manhole. The granules or tablet particles shall be placed in the storage facility before flowing water into it. The granules or tablets shall be located so that the inflowing water will ensure a current of water circulating through the calcium hypochlorite, dissolving it during the filling operation. The calcium hypochlorite shall be placed only on dry surfaces unless adequate precau-tions are taken to provide ventilation or protective breathing equipment.

4.3.1.4 Retention period. After the storage facility has been filled with the disinfecting water, it shall stand full as follows: (1) for a period of not less than 6 hr when the water entering the storage facility has been chlorinated uniformly by gas-feed equipment or chemical pump, or (2) for a period of not less than 24 hr when the storage facility has been filled with water that has been mixed with sodium hypochlorite or calcium hypochlorite within the storage facility as described in

Sec. 4.3.1.2 and 4.3.1.3.

4.3.1.5 Handling of disinfection water. After the retention period stated in

Sec. 4.3.1.4, the free chlorine residual in the storage facility shall be reduced to a concentration appropriate for distribution by completely draining the storage facility

6 AWWA C652-02

and refilling with potable water, or by a combination of additional holding time and blending with potable water having a low chlorine concentration. When an appropriate chlorine concentration is reached and subjected to satisfactory bacterio-logical testing and acceptable aesthetic quality, the water may be delivered to the distribution system.

4.3.1.5.1 The environment into which the chlorinated water is to be discharged shall be inspected, and if there is any likelihood that the chlorinated discharge will cause damage, then a reducing agent shall be applied to the water to be wasted to thoroughly neutralize the chlorine residual in the water. Federal, state, or local environmental regulations may require special provisions or permits prior to disposal of highly chlorinated water. The proper authorities should be contacted prior to disposal of highly chlorinated water.

4.3.2 Chlorination method 2. A solution of 200-mg/L available chlorine shall be applied directly to the surfaces of all parts of the storage facility that would be in contact with water when the storage facility is full to the overflow elevation.

4.3.2.1 Method of application. The chlorine solution may be applied with suitable brushes or spray equipment. The solution shall thoroughly coat all surfaces to be treated, including the inlet and outlet piping, and shall be applied to any separate drain piping such that it will have available chlorine of not less than 10 mg/L when filled with water. Overflow piping need not be disinfected.

4.3.2.2 Retention. The disinfected surfaces shall remain in contact with the strong chlorine solution for at least 30 min, after which potable water shall be admitted, the drain piping purged of the 10-mg/L chlorinated water, and the storage facility then filled to its overflow level. Following this procedure and subject to satisfactory bacteriological testing and acceptable aesthetic quality, the water may be delivered to the distribution system.

4.3.3 Chlorination method 3. Water and chlorine shall be added to the storage facility in amounts such that the solution will initially contain 50 mg/L available chlorine and will fill approximately 5 percent of the total storage volume.

This solution shall be held in the storage facility for a period of not less than 6 hr.

The storage facility shall then be filled to the overflow level by flowing potable water into the highly chlorinated water. It shall be held full for a period of not less than

24 hr. All highly chlorinated water shall then be purged from the drain piping.

Following this procedure and subject to satisfactory bacteriological testing and

DISINFECTION OF WATER-STORAGE FACILITIES 7

acceptable aesthetic quality, the remaining water may be delivered to the distribution system.

4.3.3.1 Adding chlorine. Chlorine shall be added to the storage facility by the method described in Sec. 4.3.1.1, 4.3.1.2, or 4.3.1.3. The actual volume of the 50-mg/

L chlorine solution shall be such that, after the solution is mixed with filling water and the storage facility is held full for 24 hr, there will be a free-chlorine residual of not less than 2 mg/L.

Sec. 4.4 Disinfection Procedures When Conducting Underwater Inspection of Potable-Water-Storage Facilities

4.4.1 Pre-job meeting. A pre-job meeting involving the constructor and water utility representatives shall be held to ensure the following; that the personnel understand the configuration of the reservoir, the disinfection procedures, that underwater appurtenances are identified, that time restrictions are discussed, that the diving conditions are considered, that safety procedures are in place, and that inspection requirements are understood. Any problems associated with logistics should be resolved at this time. Clear communications between utility operations personnel and the constructor are essential.

4.4.2 Storage-facility isolation. In certain instances, safe diving operations may require the water-storage facility to be removed from service and isolated from the system prior to inspection by closing all inlet and outlet valves. Flowmeters and the tank level should be monitored to verify that the facility has been isolated. The underwater inspection should be made with the reservoir as full as possible, while still leaving room for access to the roof area. If the reservoir must be inspected with the inlet/outlet valves in the open position, then system valves further upstream or downstream should be closed. Off-line inspection/cleaning of storage facilities may not be possible or convenient for certain tanks or clearwells. On-line diving work may be completed safely, but strict attention to safety is required. If special operational conditions necessitate underwater inspection or cleaning without isolation, then diving work should be done during periods when positive flow into the reservoir is maintained and rates into or out of the water-storage facility are minimal. For underwater inspection of nonisolated facilities having a common inlet/outlet pipe, it is strongly recommended that a positive flow into the storage facility be maintained during the dive.

4.4.3 Storage-facility access. Before the facility access hatch is opened, the hatch and immediate area shall be cleaned of all loose dirt and debris. Special care

8 AWWA C652-02

should be taken to keep the equipment and personnel clean prior to entering the tank. Dirt and contaminants on the reservoir roof, adjacent to the hatch can re-contaminate the equipment. If any equipment that will enter the tank makes contact with the roof, it shall be re-disinfected prior to entering the tank.

4.4.4 Initial water quality. The first step of any in-service inspection project shall be for the utility to establish the chlorine residual and turbidity in the reservoir contents before entering the reservoir for any other purpose. The utility should take representative water samples from several depth locations, if possible, and analyze for chlorine residual and turbidity. Turbidity testing is especially important if the reservoir is being cleaned or inspected while on line. The results shall be recorded for future reference.

4.4.5 Equipment and personnel requirements.

4.4.5.1 Equipment and clothing. All equipment to be used for inspection/ cleaning of potable-water-storage facilities shall be dedicated for that purpose only.

All equipment shall be constructed and maintained in such a fashion so that water quality will not be affected. All equipment shall be available for inspection.

4.4.5.1.1 According to this standard, both SCUBA (self-contained underwater breathing apparatus) and externally supplied air methods are acceptable air sources.

4.4.5.1.2 All equipment exposed to the water shall be suitable for disinfection.

Divers shall be completely encapsulated with no bare skin exposed. Diving clothing shall be of the dry-suit type and shall be in good condition, free from tears, scrapes, unrepaired areas, or other imperfections that may impair the integrity of the suit.

The diver and the clothing shall be disinfected after the diver is suited up and on top of the tank as per Sec. 4.3.2. All equipment and dry suits dedicated for potable-water underwater inspection work shall be stored in a manner that prevents both chemical and bacteriological contamination. Personnel entering a tank for the purposes of a float-down inspection must wear a dry suit that can be disinfected properly.

4.4.5.1.3 There shall be no contact of the mouth or head with the water during any underwater operations. The head shall be fully encapsulated by one or a combination of the following: helmet or dry suit hood with full-face mask.

4.4.5.1.4 Divers shall have communication in accordance with federal, state, provincial, and local regulations.

4.4.5.1.5 Underwater operations may be videotaped or documented with still photographs at the utility’s request.

DISINFECTION OF WATER-STORAGE FACILITIES 9

4.4.5.1.6 Disturbing tank bottom sediment may impair water quality. Sedi-ment may contain bacteria, which if resuspended can cause contamination. Disturbed sediment will create localized turbidity. In some cases, it may be desirable to disturb a small area of thin sediment in order to inspect the underlying coating or floor condition. Divers or ROVs shall not disturb the sediment in any way unless explicitly approved by the utility to do so; this includes “walking on the floor.”

4.4.5.2 Personnel requirements. Because of the hazardous nature of this work, combining confined-space entry and diving, the constructor performing the work shall comply with all federal, state, provincial, and local regulations.

4.4.5.2.1 Certain diving constructors who have been providing these services for many years may not have the formal certifications listed below. Utilities should carefully review the documentation of training and experience for these firms and require a detailed personal diver’s log for the personnel who will conduct the on-site work. Simply, the presentation of a sport diver certification card for SCUBA by itself is not acceptable proof of proper training.

The following is a limited list of examples of diver qualifications that are acceptable—but not without detailed documentation of training and direct tank inspection—cleaning work experience:

2nd Class US Navy Diver Training

ANSI/ACDE 01 (latest version) Commercial Diver Certification

ADC Commercial Certification

4.4.5.2.2 All personnel on the dive or float-down team must be OSHA Confined

Space Certified. These certificates should be provided on the job site for all personnel.

4.4.5.2.3 All personnel on the dive or float-down team shall be free of communicable disease and shall not have been under a physician’s care within the seven-day period prior to the entering of the facility. No person who knowingly has an abnormal temperature or symptoms of illness shall work in a water-storage facility.

4.4.5.2.4 The American Red Cross or an equivalent agency shall certify all dive team members in the use of CPR and First Aid.

4.4.5.3 Safety. The dive team shall comply with all applicable local, state, and federal safety requirements and shall provide all necessary safety equipment suitable for the specific access opening, depth to water, and other aspects of the water-storage facility to be inspected.

4.4.5.3.1 The constructor shall have a comprehensive safety manual on site, which addresses all of the potential hazards encompassed by the in-service

10 AWWA C652-02

operations. The safety manual shall include certifications for all on site employees for diving, confined space, first aid, and CPR. The constructor shall have a method and the equipment readily available for the extraction of an injured diver and a method for lowering a person to the ground who is incapacitated. This may include the use of a properly trained and equipped local fire department or rescue squad. The use of an outside response team must be covered in the pre-job meeting, and they must be able to respond quickly or be on site during the work.

4.4.6 Equipment disinfection. All equipment that will enter the water-storage facility must be disinfected immediately prior to entry into the potable-water reservoir. Any equipment making contact with the tank roof must be disinfected again prior to entry into the water. The method of equipment disinfection can be submersion in, spraying with, or sponging with disinfectant solution as defined in

Sec. 4.3.2. Care must be taken when applying disinfectant solution to the diver and equipment so that any excess, runoff, or spillage is controlled so it does not enter the reservoir.

4.4.7 Post-inspection chlorine residual and bacteriological testing. If proper disinfection procedures are followed, there should be no need to increase the chlorine residual in the storage facility after completion of the inspection. However, after all personnel and equipment are removed from the water-storage facility, the chlorine residual in the facility should be re-tested. If the chlorine residual has dropped from that indicated by the initial test made prior to entry, sufficient chlorine solution or granules shall be added to the storage facility to return the chlorine residual to pre-entry levels, but not to exceed a chlorine concentration of 2 mg/L.

Disinfectant shall be added in a manner to achieve maximum distribution over the surface and achieve all possible mixing. Adequate mixing can be promoted by circulation, if available, or with portable mixers or portable pumps suitably disinfected. (NOTE: The pre- and post-dive residuals may not match exactly because of sampling and analytical variability).

When chlorine residual is at pre-entry levels, samples for coliform organisms should be taken by the owner and analyzed in accordance with Sec. 5.1.

If the chlorine residual in the storage facility did not drop during the inspection, the facility can be returned to service (if it was isolated) as soon as the bacteriological samples have been confirmed as acceptable. However, if it was necessary to rebuild the chlorine residual in the storage facility, the facility should not be placed in service until after completion of a satisfactory bacteriological analysis.

DISINFECTION OF WATER-STORAGE FACILITIES 11

4.4.9 Affidavit of compliance. The purchasing utility may require that the constructor performing the inspection or cleaning services provide an affidavit of compliance with the requirements of this standard.

SECTION 5: VERIFICATION

Sec. 5.1 Bacteriological Sampling and Testing

5.1.1 Standard conditions. After the chlorination procedure is completed and before the storage facility is placed in service, water from the full facility shall be sampled and tested for coliform organisms in accordance with the latest edition of

Standard Methods for the Examination of Water and Wastewater. The testing method used shall be either the multiple-tube fermentation technique or the membrane-filter technique, or the enzyme substrate coliform test.

5.1.1.1 Test for odor. The water in the full facility should also be tested to ensure that no offensive odor exists because of chlorine reactions or excess chlorine residual.

5.1.1.2 Results of testing. If the test for coliform organisms is negative, then the storage facility may be placed in service. If the test shows the presence of coliform bacteria, then the situation shall be evaluated by qualified personnel. In any event, repeat samples shall be taken until two consecutive samples are negative, or the storage facility shall again be subjected to disinfection.

5.1.1.3 Care in sampling. The samples shall be taken from a sample tap on the outlet piping from the storage facility or from a sample tap connected directly to the storage facility. In either case, the operation shall be such as to ensure that the sample collected is actually from water that has been in the storage facility.

5.1.1.4 Recommended additional samples. During the disinfection operation and the required sampling of water from the storage facility, it is recommended that samples be taken from water flowing into the storage facility to determine if coliforms are present in the typical potable water source.

SECTION 6: DELIVERY

This standard has no applicable information for this section.

APPENDIX A

Chlorine Residual Testing

This appendix is for information only and is not part of AWWA C652.

SECTION A.1: DPD DROP DILUTION METHOD

(FOR FIELD TEST)

The N, N-diethyl-p-phenediamine (DPD) drop dilution method of approximating total residual chlorine is suitable for concentrations above 10 mg/L, such as those applied in the disinfection of water mains or tanks.

Sec. A.1.1 Apparatus

1. A graduated cylinder for measuring distilled water.

2. An automatic or safety pipette.

3. Two dropping pipettes that deliver a 1-mL sample in 20 drops. One pipette is for dispensing the water sample, and the other is for dispensing the DPD and buffer solutions. The pipettes should not be interchanged.

4. A comparator kit containing a suitable range of standards.

Sec. A.1.2 Reagents

1. DPD indicator solution. Prepare as prescribed in Standard Methods for the

Examination of Water and Wastewater (20 ed.), Section 4500-Cl, p. F.2b.

Sec. A.1.3 Procedure

1. Add 10 drops of DPD solution and 10 drops of buffer solution (or 20 drops of combined DPD-buffer solution) to a comparator cell.

2. Fill the comparator cell to the 10-mL mark with distilled water.

3. With a dropping pipette, add the water sample one drop at a time, mix until a red color is formed that matches one of the color standards.

4. Record the total number of drops used and the final chlorine reading obtained (that is, the chlorine reading of the matched standard).

5. Calculate the milligrams per liter of free residual chlorine as follows:

mg/L chlorine reading 200× drops of sample

14 AWWA C652-02

SECTION A.2: HIGH-RANGE CHLORINE TEST KITS

Several manufacturers produce high-range chlorine test kits that are inexpen-sive, easy to use, and satisfactory for the precision required.

APPENDIX B

Chlorine Dosages

This appendix is for information only and is not a part of AWWA C652.

Table B.1 Amounts of chemicals required to give various chlorine concentrations in 100,000 gal (378.5 m3) of water**

Sodium Hypochlorite Required

Calcium Hydrochlorite

Required

Desired Chlorine Concentration in Water mg/L

Chlorine Required lb (kg)

5 Percent Available Chlorine gal (L)

10 Percent Available Chlorine gal (L)

15 Percent Available Chlorine gal (L)

65 Percent Available Chlorine lb (kg)

2 1.7 (0.8) 3.9 (14.7) 2.0 (7.6) 1.3 (4.9) 2.6 (1.1)

10 8.3 (3.8) 19.4 (73.4) 9.9 (37.5) 6.7 (25.4) 12.8 (5.8)

50 42.0 (19.1) 97.0 (367.2) 49.6 (187.8) 33.4 (126.4) 64.0 (29.0)

*Amounts of sodium hypochlorite are based on concentrations of available chlorine by volume. For either sodium hypochlorite or calcium hypochlorite, extended or improper storage of chemicals may cause a loss of available chlorine.

Table B.2 Amounts of chemicals required to give various chlorine concentrations in 200 mg/L in various volumes of water*

Sodium Hypochlorite Required

Calcium Hydrochlorite

Required

Volume of Water gal (L)

Chlorine Required lb (kg)

5 Percent Available Chlorine gal (L)

10 Percent Available Chlorine gal (L)

15 Percent Available Chlorine gal (L)

65 Percent Available Chlorine lb (kg)

10 (37.9) 0.02 (9.1) 0.04 (0.15) 0.02 (0.08) 0.02 (0.08) 0.03 (13.6)

50 (189.3) 0.1 (45.4) 0.2 (0.76) 0.1 (0.38) 0.07 (0.26) 0.15 (68.0)

100 (378.5) 0.2 (90.7) 0.4 (1.51) 0.2 (0.76) 0.15 (0.57) 0.3 (136.1)

200 (757.1) 0.4 (181.4) 0.8 (3.03) 0.4 (1.51) 0.3 (1.14) 0.6 (272.2)

*Amounts of sodium hypochlorite are based on concentrations of available chlorine by volume. For either sodium hypochlorite or calcium hypochlorite, extended or improper storage of chemicals may cause a loss of available chlorine.

APPENDIX C

Disposal of Heavily Chlorinated Water

This appendix is for information only and is not a part of AWWA C652.

1. Check with the local sewer department for the conditions of disposal to the sanitary sewer.

2. Chlorine residual of water being disposed will be neutralized by treatment with one of the chemicals listed in Table C.1.

Table C.1 Amounts of chemicals required to neutralize various residual chlorine concentrations in 100,000 gal (378.5 m3) of water

Chemical Required

Residual Chlorine Concentration

Sulfur Dioxide

(SO2)

Sodium Bisulfite (NaHSO3)

Sodium Sulfite (Na2SO3)

Sodium Thiosulfate (Na2S2O3•5H2O mg/L lb (kg) lb (kg) lb (kg) lb (kg)

1 0.8 (0.36) 1.2 (0.54) 1.4 (0.64) 1.2 (0.54)

2 1.7 (0.77) 2.5 (1.13) 2.9 (1.32) 2.4 (1.09)

10 8.3 (3.76) 12.5 (5.67) 14.6 (6.62) 12.0 (5.44)

50 41.7 (18.91) 62.6 (28.39) 73.0 (33.11) 60.0 (27.22)

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