UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON. D.C. 20460
2 3 1378
Construction Grants
Program Requirements Memorandum
PRM No. 79-1
Subject: Safety Requirements for the Design1and Operation
of Chlorination Facilities Using Gaseous Chlorine
From: John T. Rhett, Deputy Assistant Administrator
for Water Program Operations (WH-546)
To: Regional Administrators (I-X)
Attn: Water Division Director?
Purpose:
This memorandum establishes the policy pertaining" to safety require-
ments for the design and operation of chlorination facilities utilizing
gaseous chlorine.
While many engineering considerations and operational practices
with regard to chlorine handling are site specific, a number of significant
design specifications and operational procedures should be required as
minimum acceptable practice. There are numerous publications that
provide detailed information pertaining to this subject, including those
listed in Attachment B. This memorandum provides guidelines and general
principles to be used in the design and operation of chlorination
facilities using gaseous chlorine.
Discussion:
Gaseous chlorine refers to chlorine purchased in its elemental form,
occurring in the gaseous dr-liquid state. It is supplied commercially
in pressurized containers sized to contain either 100 pounds, 150 pounds
or 2,000 pounds of chlorine. In addition, chlorine can be purchased in
single unit and multi-unit railroad tank cars, as well as tank trucks.
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Chlorine is a respiratory irritant, and under conditions of sufficient
Concentration and exposure, can cause death by suffocation. Chlorine,
especially when combined with even small amounts of water, is highly
corrosive, and can cause severe burns when brought into contact with
skin and eyes. Unfortunately, the toxic and corrosive effects of
chlorine v;ere recently demonstrated by the two publicized railroad tank
car derailments and their subsequent after effects.
The on-going construction grants program will continue to generate
significant construction of wastewater treatment facilities throughout.-
the country. Chlorination continues to represent the most commonly used
method of disinfection for sewage, and consequently many new treatment
facilities will include provisions for chlorinating treated effluent
prior to discharge. As a result, a major part of EPA's overall responsibility
is ensuring that safe chlorination practices are implemented.
EPA policy is designed to ensure that:
1. Chlorination systems are designed to prevent chlorine leaks
and to minimize operator and local resident exposure should leaks occur.
2. Chlorine leaks that do occur are handled safely, quickly, and
with minimal environmental exposure.
Policy:
Attachment A is guidance for the design and operation of safe
chlorination facilities. It is intended that in reviewing plans and
specifications and operation and maintenance manuals for those projects
incorporating chlorination processes, Sections I and II of Attachment A
be used as a technical guide and basis for minimum adequacy in safety
considerations. The information contained in the guidance was developed
to serve as-part of the overall criteria applicable to the design and
operation of such facilities. While it is believed that-complying with
the guidance will substantially reduce chlorine hazards which can be
potentially dangerous to plant personnel and nearby residents, it is
recommended that the guidance in this PRN be used to supplement other
applicable information on chlorination facilities.
Implementation:
The measures specified in this memorandum are required for all
projects that have not yet.received Step 3 grants by the date of this
memorandum. In addition, projects that have already received Step 3
grants should incorporate the sections under operation and maintenance
in the O&M manual. Where practical, current Step 3 projects should be
encouraged to make revisions to-their 'designs to comply with the measures
specified herein.
Attachments
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ATTACHMENT A
Procedure for the Safety in the Desiyn and
Operation of Chlorine Facilities
This guidance contains a detailed procedure which represents good
engineering practices for the safety in the design and operation" of
chlorination facilities. Because it is, not the intent of the guidance
to modify or replace any appropriate safety requirements and regulations
published by the Occupational Safety and Health Administration (OSHA),
it is recommended that the guidance be used to supplement the OSHA and
any other appropriate safety requirements.
I. Design of Gaseous Chlorine Facilities
A. If gas chlorination equipment a'nd chlorine cylinders are to be
installed or stored in a building used for other purposes, a gas-tight
partition should separate the chlorination room from any other portion
of the 'building. Ooors to this room should open only to the outside of
the building, and should be equipped with panic hardware. Such rooms
should be at ground level, and should permit easy access to all equipment;
the chlorine storage area(s) should be.separated from the chlorine feed
area(s).
B. A clear glass, gas-tight window should be installed in an
exteHor door or interior wall of the chlorination room to permit the
chlorinator(s) to be viewed without entering the room.
C. Chlorination rooms should be equipped with heating and ventilating
equipment designed to maintain the'room(s) containing the chlorine
containers at approximately 1S-21°C (65-70°F) and the room(s) containing
the chlorinator feed equipment at a temperature of 5-10°F higher.
0. Containers (except insulated rail or cargo tanks) should be
shielded from direct sunlight or from overheating above 60°C (140°F)
any source, either while in storage or in use. Pairs of level rails or
properly designed cradles should be provided for storing one ton cylinders.
E. Forced mechanical ventilation should be included that will
provide a complete air change at least every 1-4 minutes. Because
chlorine gas is heavier than air, location of air inlets and outlets
should be carefully considered to ensure that the entire room will be
thoroughly-ventilated. For example, in the exhaust ventilation system,
the exhaust outlet should be located near the floor, with the discharge
being positioned outside of the building at a point where it will not
contaminate the air inlet to any buildings or inhabited areas. The
fresh air inlet should be located at the opposite end of the room from
the exhaust outlet, to facilitate complete air replacement.
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F. Exhaust equipment should be automatically activated by external
light switches. That is, an operator should be able to turn the lights
on outside of the chlorination room and thereby activate the ventilation
system prior to entering the enclosed area. Other automatic systems,
including door-activated mechanisms, should also be considered.
G. Emergency shoviers aad eye baths should be located near, but
external to,'the chlorination facilities.
H. For facilities having a design hydraulic capacity of five
million gallons per day or more, an automatic chlorine detection syst&n
should be included as part of the chlorination facility. The detection
system should sound alarms and activate flashing lights jhat are audible
and visible within the POTW. Connection of the alarm system to the
local police station, POTW operator's area,' or both, is also recommended
where practical. Consideration of such detection and alarm systems
should also be given in the case of smaller facilities, where- the
potential benefits are sufficient to warrant the additional cost and
associated increase in operational complexity.
II. Operation and Maintenance
The following procedures should be included in operation and
maintenance manuals for treatment facilities which incorporate chlorination
processes. While the following criteria are related primarily to the
operation and maintenance of chlorination systems, they should also be
read in the context of their applicability to the design of treatment
plants.
A. Loading and Unloading of Chlorine
1. DOT regulations (174.560) provide that single-unit railroad
tank cars must be unloaded on a private track. • This requirement.
applies to all EPA supported projects.
2. Whenever practicable, single and multi-unit tank cars
should be delivered at a deadend siding(s) used only for chlorine
delivery, with insurance that the tracks are level. The car(s)
should be protected by a locked derail, a closed and locked switch,
or preferably both.
3. Railway flat cars delivering one ton containers should
also be delivered on a special siding assigned to chlorine unloading
only.
4. Chains, rope slings, or magnetic hoists should never be used.
When cylinders are to be lifted, forklift trucks or hoisting equipment
with special cradles or carriers designed for chlorine equipment should
be.utilized.
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5. Tank barge unloading facilities should be in con;pliance with
the Army Corps of Engineers and Coast Guard Regulations.
B. Handling of Chlorine Containers
1. One .ton cylinders should be stored on properly designed
cradles or pairs of level rails. Chocks should be placed-to prevent
the containers from rolling when unattended.
2. 100 and 150 pound cylinders should be secured with safety
chains in storage and during transport.
3. Containers should never be piled on top of one another.
4. Containers should be stored in a manner that will prevent
them from being hit by vehicles or-other heavy objects.
.5. Chlorine should not be stored with other compressed
gases.
6. Empty containers should be so tagged, and should be
stored separately from full containers.
7. Cylinders should be used in the order in which they are
received, to prevent valve packing from becoming dry arid developing
leaks.
6. Only approved tools designed for use.with chlorine container
should be used.. For example, hand trucks specifically designed for
100 and 150 pound cylinders should be used instead of rolling them
on the rim.
9. Chlorine cylinder emergency repair kits should be readily
available.
C. Leak Detection and Emergency Procedures
1. Each POTW should have a formal written set of emergency
"procedures that includes the items discussed below, prior to startup
of the chlorination facilities. In addition, operator's manual
must include pre-planned procedures in the event of a catastrophic
leak or container rupture.
2. Self-contained positive pressure helmets, with their own
compressed-air supply and full facepiece, should be available for
emergency use. The canister type gas mask is specifically not
recommended. The helmets should be located at readily accessible
points, away from the area(s) likely to be contaminated with chlorine
gas. Spare air supply cylinders should also be on site for use
during prolonged emergencies*
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Helmets and breathing air supply tanks should be routinely
inspected and maintained in good condition. They should ..be. cleaned
after each use, and also cleaned routinely at regular intervals.
When needed, air supply tanks should be refilled at stations where
proper air compressor equipment is used to filter out oil in a
contaminated air environment.
Specifications for properly designed positive pressure helmets for
chlorine service can be obtained from the U.S. Bureau of Mines,
OSHA, or NIOSH. In addition, potential users of these helmets, as
well as users of other emergency equipment, should have" formal
training in their use and should also be required to have regular
practice sessions.
3. A strong solution of aqueo'us ammonia (18° Baume or higher)
should be available for use in locating the source of leaks. Dense
white clouds of a^rr-oniuni chloride .are formed by the reaction of the
ammonia and chlorine, thus confirming the source of the chlorine
leak.
4. Repair of any chlorine leaks should be performed by at
least two people wearing self-contained air breathing equipment.
If such repairs must be made below grade, persons entering the area
must also wear safety harnesses which are connected to. ropes extending
to a higher level where additional people are stationed to assist
in emergency rescue operations.
5. Piping and valves in chlorine rooms -should be color coded
and properly labeled for rapid identification.
6. • If a container is leaking chlorine, it should be turned,
if possible, so that gas instead of liquid escapes. The quantity
of chlorine that escapes froni a'gas leak is about one-fifteenth the
amount that escapes from a liquid leak through the same size hole.
7. If possible, a leaking container should be moved to an
isolated spot where "it will do the least harm.
8. Never immerse or throw a leaking chlorine container into
a body of water. The leak will be aggravated and the container may
float when still partially full of liquid chlorine, allowing gas
evolution at', the surface.
9. Emergency.kits should be readily available for the quick
repair of chlorine leaks. Information on emergency .kits is available
from the Chlorine Institute, New York, NY.(see Reference 1).
10. In the event of an emergency, technical assistance can be
obtained by'calling CHEMTREC (Manufacturing Chemists Association,
Chemical Transportation Emergency Center) at 800/424-9300. This is
a 24-hour toll-free service.'
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ATTACHMENT B
1. "Chlorine Mtinual ," The Chlorine Institute, Inc. 342 Madison-Avenue,
New York, NY, December, 1972.
2. "VIPCF Manual of Practice No. 1 - Safety -in Wastewater Works," Water
Pollution Control Federation, 1975.
3. "K'PCF Manual of .Practice No. 4 - Chlorination of Hastewater," Water
Pollution Control Federation, 1976.
4. "WPCF Manual of Practice No. 3 - Wastewater Treatment Plant Design,"
Water Pollution Control Federation, 1977.
5. "Liquid Chlorine" Technical and Engineering Service Bulletin flo. 7,
Allied Chemical, Morristown, NJ.
6. "Chemical Safety Data Sheet SD-80, Properties and Essential Information
for Safe Handling and use of Chlorine," Manufacturing Chemists
Association, 1970.
7. "Standards for Waste Treatment Works, Municipal Sewerage Facilities,"
New York State Department of Environmental Conservation, 1970.
8. "Chlorine Handbook," Diamond Shamrock Chemical Company, 1976.
9. "Dow Chlorine Handbook," Dow Chemical U.S.A., 1975.
10. Sax, Irving N., Dan_gerous_ Properties of Industrial Materials, Van
Nostrand Reinhold Company, 1975.
11. tfnite, George C., Handbook Of Chlorination, Van Nostrand Reinhold Company,
1972.
12. "Hazardous Materials Regulations of the Department of Transportation,
Including Specifications for Shipping Containers," R.M. Grazianos Tariff.
Publishing.
13. "Chlorine Detector Saves a Life," Public l-'orks, March, 1978.
14. "Safe Handling of Compressed Gases and"Containers," Compressed Gas
Association, -Inc., 1974.
15. "Supplement lo Federal Guidelines: Design, Opor.ition and Maintenance
of Wastewater Treatment Facilities," technical Bulletin flo. D-71-1,
U.S..Environmental Protection Agency, September, 1970.
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