United States Office Of Water EPA 812-B-92-001
Environmental Protection (EN-336) NTIS No. PB92-173-236
Agency June 1992
x>EPA Guidance To Protect POTW
Workers From Toxic And
Reactive Gases And Vapors
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DISCLAIMER:
This is a guidance document only. Compliance with these procedures cannot
guarantee worker safety in all cases. Each POTW must assess whether
measures more protective of worker health are necessary at each facility.
Confined-space entry, worker right-to-know, and worker health and safety issues
not directly related to toxic or reactive discharges to POTWs are beyond the
scope of this guidance document and are not addressed.
Additional copies of this document and other EPA documents referenced in this
document can be obtained by writing to the National Technical Information
Service (NTTS) at:
S28S Port Royal Rd.
Springfield, VA 22161
Ph #: 703-487-4650
(NTIS charges a fee for each document.)
PiMM on piper th* contain*
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FOREWORD
In 1978, EPA promulgated the General Prctreatment Regulations [40 CFR Part 403] to control
industrial discharges toPOTWs that damage the collection system, interfere with treatment plant operations,
limit sewage sludge disposal options, or pass through inadequately treated into receiving waters. On Jury 24,
1990, EPA amended the General Prctreatment Regulations to respond to the findings and recommendations
of the Report to Congress on the Discharge of Hazardous Wastes to Publicly Owned Treatment Works (the
"Domestic Sewage Study"), which identified ways to strengthen the control of hazardous wastes discharged to
POTWs. The amendments add two prohibitions addressing POTW worker health and safety to the specific
discharge prohibitions that apply to all non-domestic dischargers to POTWs. At 40 CFR 403.5(b)(l) and
403.5(b)(7), respectively, the new regulations prohibit:
• pollutants which create a fire or explosion hazard in the POTW, including, but not limited to,
wastestreams with a closed-cup flashpoint of less than 140* F or 60* C using the test methods
specified in 40 CFR 261.21; and
• pollutants which result in toxic gases and vapors within the POTW in a quantity that may cause
acute worker health and safety problems.
The Guidance to Protect POTW Workers From Toxic and Reactive Gases and Vapors fulfills EPA's
commitment to issue guidance for POTWs on implementing the new specific prohibitions. The guidance
document is designed to:
• help the POTWs understand reactive and gas/vapor-toxic hazards and how they happen,
• give the POTWs working knowledge of certain chemicals that cause reactive and gas/vapor-toxic
conditions within the POTW and at industries during inspection, and
• recommend procedures to prevent or mitigate reactive and gas/vapor-toxic conditions.
The new specific prohibitions, together with this guidance should enable POTWs to improve protection
of POTW workers from the serious health and safety problems that can occur from exposure to toxic and
reactive substances in industrial discharges.
Michael B. CooRv Director
Office of Wastewater Enforcement and Compliance
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TABLE OF CONTENTS
Page
LIST OF APPENDICES v
LIST OF TABLES vi
LIST OF FIGURES vi
1. INTRODUCTION 1-1
1.1 BACKGROUND 1-1
1.2 PURPOSE AND ORGANIZATION OF THIS MANUAL 1-4
2. DEFINING REACTIVE AND GAS/VAPOR-TOXIC HAZARDS 2-1
2.1 REACTIVITY 2-1
2.2 GAS/VAPOR TOXICITY 2-3
3. MONITORING TO IDENTIFY REACTIVE AND GAS/VAPOR-TOXIC HAZARDS 3-1
3.1 WASTEWATER MONITORING EQUIPMENT 3-2
3.2 AIR MONITORING EQUIPMENT 3-3
3.2.1 Monitoring for Oxygen Content 3-3
3.2.2 Monitoring for Explosivity 3-5
3.2.3 Monitoring for Organic Vapors and Gases 3-6
4. SCREENING INDUSTRIAL DISCHARGES 4-1
4.1 DEVELOPING WASTEWATER SCREENING LEVELS
BASED ON GAS/VAPOR TOXICITY 4-1
4.1.1 Step 1: Identify Gas/Vapor Toxicity Criteria 4-1
4.1.2 Step 2: Convert Gas/Vapor Toxicity Criteria to Wastewater Screening Levels 4-4
4.1.3 Step 3: Compare Wastewater Screening Levels to Current Discharge Levels 4-6
4.1.4 Screening for Gas/Vapor-Toxic Mixtures 4-6
4.1.5 Screening for Reactivity 4-6
4.2 CINCINNATI METROPOLITAN SANITARY DISTRICT (CMSD)
SCREENING PROCEDURE 4-8
5. PROBLEM IDENTIFICATION PROCESS 5-1
5.1 PHASE 1: COLLECT INFORMATION 5-1
5.1.1 Identify Data Collection Needs 5-1
5.1.2 Perform File Reviews 5-4
5.1.3 Conduct Inspections and Field Evaluations 5-8
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TABLE OF CONTENTS (Continued)
Page
5.2 PHASE 2: PERFORM HAZARDS ANALYSIS 5-14
5.2.1 Evaluating Chemical Management Practices 5-14
5.2.2 Screening Industrial Discharges 5-15
5.3 SURVEYING THE POTW 5-17
5.3.1 Collection System Concerns 5-17
5.3.2 Treatment Plant Concerns 5-17
6. CONTROL OF POTENTIAL HAZARDS 6-1
6.1 CONTROLLING HAZARDS AT INDUSTRIAL USERS 6-1
6.1.1 Legal Authority 6-1
6.1.2 Specific Industrial User Requirements 6-2
6.1.3 OSHA Exposure Limits 6-6
6.2 CONTROLLING HAZARDS AT THE POTW 6-7
6.2.1 Data Collection and Hazard Identification 6-8
6.2.2 Worker Training 6-8
6.2.3 Hazard Detection Equipment 6-9
6.2.4 Personal Protective Equipment 6-10
IV
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LIST OF APPENDICES
APPENDIX A
APPENDIX B -
APPENDIX C -
APPENDIX D -
APPENDIX E -
APPENDIX F -
APPENDIX G -
APPENDIX H -
APPENDIX I -
APPENDIX J -
APPENDIX K -
APPENDIX L -
- LOWER EXPLOSIVE LIMITS
SCREENING TECHNIQUE TO IDENTIFY GAS/VAPOR-TOXIC
DISCHARGES
SCREENING TECHNIQUE TO IDENTIFY FLAMMABLE/EXPLOSIVE
DISCHARGES
SAMPLE HEADSPACE MONITORING ANALYTICAL PROCEDURE
(CINCINNATI APPROACH)
VOLATILE ORGANIC PRIORITY POLLUTANTS
INFORMATION COLLECTION/DECISION SHEET
STATES WITH APPROVED OSHA PLANS (AUGUST 1991)
TYPES OF RESPIRATORS
EFFECTIVENESS OF PROTECTIVE MATERIALS AGAINST CHEMICAL
DEGRADATION (BY GENERIC CLASS)
PROTECTIVE CLOTHING
GLOSSARY
BIBLIOGRAPHY
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LIST OF TABLES
Table Page
1-1 HEALTH INCIDENTS CAUSED BY INDUSTRIAL DISCHARGES TO POTWS 1-2
1-2 DISCHARGES TO POTWS CAUSING FIRES OR EXPLOSIONS 1-3
2-1 COMMON CHEMICAL INCOMPATIBILITIES 2-2
3-1 INSTRUMENTATION COSTS 3-2
4-1 SOME PRIORITY POLLUTANTS WITH THEIR RESPECTIVE
THRESHOLD LIMIT VALUES 4-3
4-2 DISCHARGE SCREENING LEVELS BASED ON
GAS/VAPOR TOXICITY AND EXPLOSIVITY 4-7
6-1 STATES AND TERRITORIES WITH OSHA-APPROVED WORKER
HEALTH AND SAFETY PROGRAMS 6-6
LIST OF FIGURES
Figure Page
5-1 PROBLEM IDENTIFICATION PROCESS 5-2
5-2 SAMPLE INFORMATION COLLECTION/DECISION SHEET 5-5
5-3 SAMPLE FACILITY HAZARD SUMMARY SHEET 5-9
5^ SAMPLE WATER BALANCE WORKSHEET 5-12
VI
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1. INTRODUCTION
1.1 BACKGROUND
Publicly owned treatment works (POTWs) commonly transport and treat wastewaters from industrial users.
As a result, POTW employees may incur safety or health risks from exposure to hazardous materials in these
wastewaters. Such health effects include nausea, headaches, dizziness, skin irritation, respiratory distress, or
even cancer or sudden death. (See Table 1-1.) Gases and vapors that form or accumulate in the collection
system or volatilize in the treatment plant may pose a serious fire or explosion risk. (See
Table 1-2.)
Recognizing that exposure of POTW workers to toxic and reactive chemicals is a serious health and safety
problem, the U.S. Environmental Protection Agency (EPA) issued regulations to require POTWs to identify and
control potential exposures to substances in industrial wastewaters that are reactive or that create toxic gases and
vapors. In 1978, EPA promulgated the General Pretreatment Regulations [40 CFR Part 403] to control
industrial discharges to POTWs that damage the collection system, interfere with treatment plant operations,
limit sewage sludge disposal options, or pass through inadequately treated into receiving waters. On July 24,
1990, EPA amended the General Pretreatment Regulations to respond to the findings and recommendations of
the Report to Congress on the Discharge of Hazardous Wastes to Publicly Owned Treatment Works (the
"Domestic Sewage Study"), which identified ways to strengthen the control of hazardous wastes discharged to
POTWs. The amendments add two prohibitions addressing POTW worker health and safety to the specific
discharge prohibitions that apply to all non-domestic dischargers to POTWs. At 40 CFR 403.5(b)(l) and
403.5(b)(7), respectively, the new regulations prohibit:
(1) pollutants which create a fire or explosion hazard in the POTW, including, but not limited to,
wastestreams with a closed-cup flashpoint of less than 140* F or 60* C using the test methods
specified in 40 CFR 261.21; and
(2) pollutants which result in toxic gases and vapors within the POTW in a quantity that may cause acute
worker health and safety problems.
Materials that cause a fire.explosion, or intense chemical reaction are, for purposes of this manual, referred to
as "reactive" materials. Materials that contain or generate toxic gases and vapors within the POTW are referred
to as "gas/vapor-toxic" materials. Formal definitions of these terms are provided in Chapter 2.
1-1
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TABLE 1-1. HEALTH INCIDENTS CAUSED BY INDUSTRIAL DISCHARGES TO POTW
Source(s)
Kominsky, et al. 1980
Elia, et al. 1983
Salisbury, et al, 1982
USEPA 1986 (DSS)
USEPA 1986 (DSS)
USEPA 1986 (DSS)
USEPA 1986 (DSS)
USEPA 1986 (DSS)
USEPA 1986 (DSS)
USEPA 1986 (DSS)
USEPA 1986 (DSS)
USEPA 1986 (DSS)
McGlothlin and Cone 1981
Lucas 1982
Pederson and Simonsen 1982
Carson and Lichty 1984
Kraut, et al. 1988
Tozzi 1990
Locality
Louisville
Memphis
Roswell
Baltimore
Louisville
Mount Pleasant
Passaic Valley
Pennsauken
St. Paul
South Essex
Tampa
Gloucester County
Cincinnati
Cincinnati
NA
Omaha
New York City
Bergen County
State
KY
TN
GA
MD
KY
TN
NJ
NJ
MN
MA
FL
NJ
OH
OH
NA
NE
NY
NJ
Year
77
78
79
80-85
80-85
80-85
80-85
80-85
80-85
80-85
80-85
80-85
81
81
82
83
86
88
Industrial User Category
Pesticide manufacturing
Pesticide manufacturing
Not Identified
Paint manufacturing
Not Identified
Hazardous waste treatment
Leather tanning
Organic chemicals
manufacturing
Electronics, metal finishing,
printing
Leather tanning
Not Identified
Not Identified
Pigment manufacturing
Not Identified
Not Identified
Not Identified
Not Identified
Not Identified
Pollutants
hexachlorocyclopentadiene& fuel oil
hexachlorocyclopeniadiene,chlonUne,
hexachlorobicyclopentadiene
1 , 1 , 1-trichloroethane, aliphatica
benzene, toluene, solvents
hexane
organics, metals
volatile compounds, solvents
benzene, toluene, phenol, chloroform
solvents
hexavalent chromium
organic solvent
1,1,1 -trichloroethane
1,1,1 -trichloroethane, mineral spirits
hexane, toluene, xylene, aliphatic
naphtha, 1,1, 1-trichloroethane,
trichloroethylene, chlorobenzene,
O-chlorotoluene, trichlorobenzene
carbon dioxide
hydrogen sulfide
benzene, toluene, other organic solvents
organic solvents
Symptoms
Skin &. eye irritation, sore throat, cough
Eye, throat, nose, lung, A. skin irritation
Headache, fatigue, nausea &. eye
irritation, cough
Nausea
Nausea
Nausea
Shortness of breath, skin irritation
Shortness of breath, watery eyes
Headaches
Skin irritation
Nausea
Fatality by inhalation
Irritation of the eye* & nose, nausea,
dizziness, vomiting, acute bronchitis
Eye & nose irritation, difficulty in
breathing
Unconsciousness & two resulting
drowning*
One death, nose & throat irritation,
numbness, tingling of hand* & feet,
nausea, vomiting, & fatigue
Lightheadedness, fatigue, increased sleep,
nausea, headaches
Headaches, difficulty in breathing
NA - Not Available
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TABLE 1-2. DISCHARGES TO POTWS CAUSING FIRES OR EXPLOSIONS*
State
PA
OH
TN
OH
IL
OH
KY
PA
NJ
Year
66
69
70
70
71
77
81
83
86
Pollutants
methane, chlorine
crude oil
gasoline
gasoline
xylol, benzene, toluene
petroleum naphtha,
acetone, isopropyl alcohol
liquid hexane
methane gas, chlorine,
hydrogen sulfate gas
gasoline
Origin of Discharge
Unknown.
Oil pipeline ruptured sending an estimated
77,000 gallons into the sewer.
Valve left open on bulk storage tank sending
46,000 gallons to sewer.
Gasoline entered sewer from leaking pump and
flushing of a spill at another pump.
Accidental discharge at chemical plant.
Accidental discharge by rubber manufacturer.
Accidentally spilled into sewer.
Unknown.
Gasoline was illegally dumped into a sink by
workers at a manufacturing site.
Results
Explosion occurred in sewage treatment plant.
No injuries reported.
15 explosions occurred.
No injuries reported.
Sewage treatment plant damaged.
Raw sewage released to river.
Slight damage to sewer. No injuries reported.
A series of explosions occurred.
No injuries were reported.
Multiple explosions occurred, damaging water
and gas mains, roads, playgrounds, and a
church.
A series of explosions occurred in sewer,
damaging sewers and ripping holes in streets.
Explosion and fire occurred in sewage treatment
plant. Two deaths and 13 injuries were reported.
Explosion occurred at lift station.
One injury was reported.
* Adapted from the "National Fire Protection Association Summary of Incidents in WastewaterTreatment Plants." Casey C. Grant, memorandum to the TechnicalCommittee on
WastewaterTreatment Plants. February 22,1991.
Many of the events listed in table 1-2 were caused by accidental slug discharges to sewers. For additional information on controlling slug
discharges to POTWs, please see the EPA guidance manual Control of Slug Loadings to POTWs (1991).
1-3
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1.2 PURPOSE AND ORGANIZATION OF THIS MANUAL
This manual is intended to help POTWs carry out EPA's July 24, 1990, regulations that prohibit reactive
and gas/vapor-toxic discharges to POTWs. It also will help POTWs and their workers identify, prevent, and
mitigate hazards associated with toxic gases, vapors, and chemically-reactive substances encountered in the
POTW's collection system and treatment plant, as well as at industrial facilities during POTW inspections.
This manual has three specific purposes:
• to help POTW staff and management understand reactive and gas/vapor-toxic hazards and how they
arise;
• to give POTW staff and management a working knowledge of certain chemicals that can cause reactive
and gas/vapor-toxic conditions within the POTW and at industries during inspections; and
• to recommend procedures to prevent or mitigate reactive and gas/vapor-toxic conditions.
The manual is organized into the following chapters:
• Defining Reactive and Gas/Vapor-Toxic Hazards (Chapter 2) — Provides working definitions and
characteristics of reactive and gas/vapor-toxic substances.
• Monitoring to Identify Reactive and Gas/Vapor-Toxic Hazards (Chapter 3) — Introduces a variety of
field instruments and explores procedures for direct measurement of reactive and gas/vapor-toxic
hazards.
• Screening Industrial Discharges (Chapter 4) — Presents screening procedures for determining whether a
specific industrial discharge can cause gas/vapor-toxic conditions.
• Problem Identification Process (Chapter 5) — Presents specific inspection procedures that POTW
personnel may use, incorporating the tools described in the preceding chapters, to identify actual or
potential hazards from reactive and gas/vapor-toxic compounds.
• Control of Potential Hazards (Chapter 6) — Presents techniques for preventing and controlling reactive
and gas/vapor-toxic hazards.
The appendices provide further background information and a glossary.
1-4
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2. DEFINING REACTIVE AND GAS/VAPOR-TOXIC HAZARDS
This chapter will provide POTW personnel with a basic understanding of reactive and gas/vapor-toxic
materials and their hazards. Section 2.1 defines and characterizes reactive materials, and Section 2.2 discusses
gas/vapor-toxic materials. Table 2-1 documents chemical incompatibilities that include both reactive and
gas/vapor-toxic hazards.
2.1 REACTIVITY
"Reactive" substances undergo rapid chemical transformations into other substances. These transformations
may: (1) cause direct injury through chemical reactions; (2) generate intense heat, which can start fires or
explosions or cause burn injuries; or (3) generate toxic gases or vapors.
EPA regulates reactive wastes as hazardous wastes under the Resource Conservation and Recovery Act
(RCRA). Under EPA's hazardous waste regulations [40 CFR 261.23(a)], a solid waste exhibits the RCRA
characteristic of reactivity if it:
• is normally unstable and readily undergoes violent change without detonating;
• reacts violently with water;
• forms potentially explosive mixtures with water;
• generates potentially harmful quantities of toxic gases or vapors when mixed with water;
• may detonate or explode if subjected to a strong initiating source or if heated under confinement;
• may detonate or explode at standard temperature and pressure; or
• is a forbidden Class A or Class B explosive pursuant to 49 CFR Part 173.
Reactive substances typically fall into one of the following three categories:
• Water-reactive substances — These substances may explode or release enough heat when in contact with
water to cause fires or generate toxic gases or vapors. They include fluorine, which reacts with water to
produce hydrofluoric acid mists; and phosphorus trichloride, which in water evolves gaseous hydrogen
chloride.
• Air-reactive substances — These substances may cause fires or explosions, and may generate toxic gases,
or vapors.
— Flammable air-reactives include hydrocarbon solvents (such as hexane, tolue^^, naphtha) and fuels
(such as gasoline).
— Explosive air-reactives (such as nitroglycerine, dynamite, TNT, and lead azide) readily undergo rapid,
violent combustion which may be triggered by impact, friction or heat.
— Other solvents, such as methylene chloride, generate toxic gases upon combustion.
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TABLE 2-1. COMMON CHEMICAL INCOMPATIBILITIES
ALKALI METALS (such as calcium, potassium and
sodium) with water, carbon dioxide, carbon
tetrachloride, and other chlorinated hydrocarbons
ACETIC ACID with chromic acid, nitric acid,
hydroxyl-containing compounds, ethylene glycol,
perchloric acid, peroxides, and permanganates
ACETONE with concentrated sulfuric and nitric
acid mixtures, aniline.
ACETYLENE with copper (tubing), fluorine,
bromine, chlorine, iodine, silver, and mercury
AMMONIA (anhydrous) with mercury halogens,
calcium hypochlorite, or hydrogen fluoride,
chlorine, iodine
AMMONIUM NITRATE with acids, metal
powders, flammable fluids, chlorates, nitrates,
sulphur, and organic aerosols or other combustibles
ANILINE with acetone; or nitric acid, hydrogen
peroxide, or other strong oxidizing agents
BROMINE with ammonia, acetylene, butadiene,
butane, hydrogen, sodium carbide, turpentine, or
powdered metals
CHLORATES with ammonium salts, acids, metal
powders, sulfur, sugar, carbon, organic aerosols, or
other combustibles
CHLORINE with ammonia, acetylene, butadiene,
benzene and other petroleum fractions, hydrogen,
sodium carbides, turpentine, and powdered metals
CHROMIC ACID with acetic acid, naphthalene,
camphor, alcohol, glycerine, turpentine, and other
flammable liquids
CYANIDES with acids
HYDROCARBONS (generally) with fluorine,
chlorine, bromine, chromic acid, or sodium
peroxide
Source: Adapted from "Safety and Health in Wastewater Systems," Water Pollution Control
Federation, 1983. (The Water Pollution Control Federation is now the Water Environment
Federation.)
HYDROGEN PEROXIDE with copper, chromium,
iron, most metals or their respective salts,
flammable fluids and other combustible materials,
aniline, and nitro-methane
HYDROGEN SULFIDE with nitric acid, oxidizing
gases, metal oxides, copper, or hydrated iron oxide
(wet rust)
IODINE with acetylene, ammonia, or aluminum
MERCURY with acetylene, fulminic acid, or
hydrogen
NITRIC ACID with acetic, chromic and
hydrocyanic acids, aniline, carbon, hydrogen
sulfide, hydrazine, flammable fluids or gases, and
substances that readily become nitrated
OXYGEN with hydrogen, flammable liquids, solids,
and gases
OXALIC ACID with silver, mercury,
permanganates, or peroxide.
PERCHLORIC ACID with acetic anhydride,
hydrazine bismuth and its alloys, alcohol, paper,
wood, and other organic materials
PHOSPHORUS PENTOXIDE with water
POTASSIUM PERMANGANATE with glycerine,
ethylene glycol, benzaldehyde, or sulfuric acid
SODIUM PEROXIDE with any oxidizable
substances, such as methanol, glacial acetic acid,
acetic anhydride, benzaldehyde, carbon disulfide,
glycerine, ethylene glycol, ethyl acetate, and
furfural
SULFURIC ACID with chlorates, perchlorates,
permanganates, oxilates, formates, chlorides,
florides, and water
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Organic-reactive substances (corrosives) — May react directly with organic tissues or generate sufficient
heat upon reaction to cause bums. Also react violently with hydrocarbon solvents. Consist of the
following categories:
— Strong acids include sulfuric acid, nitric acid, hydrochloric acid, and perchloric acid.
— Strong bases include caustic soda, lye, and lime.
— Oxidizing agents include potassium dichromate, potassium permanganate, hydrogen peroxide, fluorine,
nitrous oxide, and chlorine.
— Reducing agents include sodium borohydride, lithium aluminum hydride, phosphorus, lithium,
potassium, and metallic sodium.
— Heavy metal chloride and sulfate salts include alum, ferric chloride, ferric sulfate, and aluminum
chloride, which produce strong acids in water.
— Sodium, calcium, and potassium salts of strong bases include sodium, calcium, and potassium oxide,
carbonate, hypochlorite, sulfide, and silicate, which produce strong bases in water.
2.2 GAS/VAPOR TOXICITY
This manual designates substances as "gas/vapor toxic" if they generate gases or vapors injurious to human
health. Gas/vapor-toxic effects can either be acute (causing systemic poisoning, asphyxiation, or irritation of
the eyes, skin, respiratory passages) or chronic (causing cancer).
This manual classifies gas/vapor-toxic substances according to how they generate toxic gases or vapors:
• Reactive gas/vapor-toxic substances — These substances are generated as a direct result of either an
acid-base reaction or an oxidation-reduction reaction.
— Acid-base reactions — When a volatile weak acid, or a salt of a volatile weak acid, is introduced to a
strongly acidic wastewater, fumes of the volatile acid are emitted. Similarly, when a volatile weak
base, or a salt of a volatile weak base, is introduced to a strongly basic wastewater, fumes of the
volatile base are emitted. For example:
• Hydrogen cyanide gas is evolved when a strong acid (such as sulfuric, nitric, or hydrochloric acid)
is introduced to a wastestream bearing sodium or potassium cyanide.
• Hydrogen sulfide gas is evolved when a strong acid is introduced to a sulfide-bearing wastestream.
• Ammonia gas is evolved when a strong base (such as lye, caustic soda, or lime) is added to a
wastestream bearing ammonium hydroxide (dissolved ammonia).
— Oxidation-reduction reactions — An oxidation-reduction reaction is a chemical transformation in which
electrons are transferred from one chemical (the reducing agent) to another chemical (the oxidizing
agent). In oxidation-reduction reactions involving transfer of oxygen from one molecule to another,
the molecule losing the oxygen is the oxidizing agent and the molecule gaining the oxygen is the
reducing agent.
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• Volatile gas/vapor-toxic substances — Generated through volatilization, either from aqueous solution
or from liquid or solid, rather than through chemical reaction. Hydrocarbon solvents such as benzene,
toluene, and naphtha are examples of volatile gas/vapor-toxic substances. Many volatile gas/vapor-toxic
chemicals, such as hydrocarbon solvents, are also flammable.
• Asphyxiant gas/vapor-toxic substances — Generate oxygen-deficient atmospheres by displacing oxygen.
Include methane, hydrogen sulfide, and nitrogen. Some asphyxiant gas/vapor-toxic substances, such as
methane and hydrogen sulfide, are also flammable or explosive; some (such as hydrogen sulfide) are also
highly toxic apart from their asphyxiant properties.
The most recent versions of the following documents provide information on identifying reactive and
gas/vapor-toxic chemicals and associated hazards:
• NFPA 49—Hazardous Chemicals Data, National Fire Protection Association, Quincy, MA.
• Condensed Chemical Dictionary, Gessner Hawley (editor), Van Nostrand Reinhold, New York, NY.
• Safety and Health in Wastewater Systems, Manual of Practice I, Water Pollution Control Federation,
Alexandria, VA.
• Dangerous Properties of Industrial Materials, N. Irving Sax, Van Nostrand Reinhold, New York, NY.
• Pocket Guide to Chemical Hazards (NIOSH 90-117), National Institute for Occupational Safety and
Health, U.S. Government Printing Office, Washington, DC.
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3. MONITORING TO IDENTIFY REACTIVE AND GAS/VAPOR-TOXIC HAZARDS
As a basic safety procedure, POTW personnel with proper training and knowledge of the use of air
monitoring equipment should periodically monitor their surroundings, including manholes, wet wells, and sewer
lines, to determine whether reactive or gas/vapor-toxic conditions exist. They should also be familiar with the
history and process areas of any industries being inspected or sampled, the potential hazards present, and the
type of monitoring that might be required at those industries.
Because most hazards to POTW workers occur through direct contact with wastewaters or exposure to toxic
gases or vapors, this chapter deals with wastewater and air monitoring equipment, particularly direct-reading
equipment. POTW personnel should monitor to ascertain the safety of the work area, to institute appropriate
protective measures (such as personal protective equipment or evacuation), and to identify the need for further
monitoring.
Direct-reading instruments (providing real time measurements) were developed as early warning devices for
industrial settings, where a leak or accident could release a high concentration of a known chemical. Because
they are not designed for POTW use, direct-reading instruments have certain limitations:
• They detect or measure only specific classes of chemicals;
• They may fail to measure or detect airborne substances below certain concentrations (such as 1 part per
million (ppm)); and
• They occasionally give false readings due to chemical or other interferences.
To understand advantages and limitations of direct-reading instruments read the manufacturer's instructions
carefully, and, if necessary, raise questions with the vendor's technical representatives.
Table 3-1 lists the commonly-used wastewater and air monitoring instruments that will be discussed in this
chapter, and their approximate costs.
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TABLE 3-1 INSTRUMENTATION COSTS
Instrument
Approximate Cost
(in t»l DoUin)
WASTEWATER:
pH meter
AIR:
Redox potential meter
— hand held
— laboratory
Flashpoint tester
(closed-cup)
CGD/O2 meter
Photoionization detector
— calibration kit
Flame ionization detector
— calibration kit
Colorimetric tubes
— bellows and pump
$269
$150
$1,000
$1,500
$2,000
$4,500
$150
$6,000
$150
$4 each
$330
3.1 WASTEWATER MONITORING EQUIPMENT
This section discusses methods for measuring corrosivity, oxidation-reduction, and flammability hazards in
wastewater.
Corrosivitv. pH is a measure of acidic intensity. Alkalinity, a measure of a wastewater's tendency to resist
pH change upon acid addition, measures acid-neutralizing capability. A pH meter measures the acidic or
alkaline strength of a wastestream. A wastestream of pH less than or equal to 2.0 is strongly acidic; greater
than or equal to 10.0 is strongly basic.
Oxidation-reduction. An oxidation-reduction ("redox") meter identifies the presence of oxidizing or
reducing agents, and is used in the field to measure a wastestream's tendency to carry out oxidation-reduction
reactions (defined on p. 2-3). A large positive reading on the redox meter indicates the presence of a strong
3-2
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oxidizing agent; a large negative reading indicates the presence of a strong reducing agent. Either extreme
indicates the potential for an oxidation-reduction reaction.
Flammability. Ignitable materials discharged to POTWs can cause fires and explosions in collection
systems—particularly near the point of discharge to the sewer, where high temperatures promote evaporation of
ignitable wastes into a relatively fixed volume of air and form vapors that are trapped within the collection
system. These vapors can be ignited by electric sparks, friction, surfaces such as manhole covers heated by the
sun, or heat generated by chemical reactions. Often POTW workers use metal tools that can accidentally strike
against the street, concrete surface, or manhole cover, creating sparks.
The flammability of a wastewater sample can be detected in a laboratory with a flashpoint tester. Operation
of a flashpoint tester is straightforward: a sample is collected at the point of discharge to the sewer, placed in
the tester, heated slowly, and a flame is introduced periodically to the vapor space. The flashpoint is the lowest
temperature at which vapor combustion spreads away from its source of ignition. Although two classes of
flashpoint testers exist (open-cup and closed-cup), the specific prohibition against discharges that create a fire or
explosion hazard in the POTW specifies a closed-cup flashpoint limit only. A substance's flammability, as
derived using a closed-cup flashpoint tester, is characterized as the minimum ambient temperature at which a
substance gives off sufficient vapor to create an ignitable mixture. EPA defines a flammable/explosive material
as any wastestream with a closed-cup flashpoint less than 140* F or 60* C [40 CFR 403.S(b)].
3.2 AIR MONITORING EQUIPMENT
During normal work activities such as wet well inspections and inspections of industrial users, POTW
workers should monitor the quality of the air before entering the area in which they work. The need for
monitoring may be repeated or even continuous, depending on the likelihood of changing conditions. This section
describes the equipment used for monitoring oxygen content, explosivity, and the concentration of toxic organic
and inorganic gases or vapors.
Calibration methods for air monitoring equipment are not addressed in this section. The calibration and
maintenance instructions in the operator's manual should be followed closely. Regular calibration and
maintenance of air monitoring equipment is important and should be stressed in POTW management practices.
3-3
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3.2.1 Monitoring for Oxygen Content
The normal oxygen content of the atmosphere at sea level is 20.8% by volume. Areas with oxygen levels
lower than 19.5 % are highly dangerous should not be entered without specialized training and equipment.
Criteria developed by the National Institute of Occupational Safety and Health (NIOSH) require workers to use
supplied-air respirators in areas in which atmospheric oxygen content is less than 19.5%. Oxygen levels at or
above 25 % constitute a severe fire hazard; when such levels are observed, workers should be evacuated and fire
officials contacted.
Not only is lack of oxygen a respiratory hazard, but it also provides a warning that the oxygen may have been
displaced by a potentially toxic, flammable, or explosive gas or vapor. Before work is initiated in an
oxygen-deficient atmosphere, additional monitoring—and perhaps laboratory analysis—is necessary to pinpoint
which gases and vapors are present.
Commonly, oxygen monitoring is performed with an oxygen meter, in which chemical reactions between
atmospheric oxygen and an electrolytic solution across a semipermeable membrane produce a slight electrical
current. The reaction and the resulting current increase with the amount of atmospheric oxygen present. Most
oxygen meters provide a direct readout of the percentage of oxygen present; in so doing, they help determine
whether oxygen levels are present at which air-reactive chemicals might explode or undergo rapid combustion.
By identifying the percentage of oxygen present, an oxygen meter can help POTW personnel determine whether
the ratio of oxidant to fuel mixture is sufficient for ignition. For ignition to occur, an electric spark or friction
is necessary. Oxygen meters should be explosion proof, and equipped with audible and visible alarms.
An oxygen meter has two principal operating components: the oxygen sensor and the meter readout. In
some units, an aspirator bulb or pump draws air into the detector and across the detector cell; in others, air is
allowed to diffuse to the sensor. Some detectors are small hand-held units. Many have single-aspirating (hand
squeeze) bulb pumps or battery-powered diaphragm pumps to draw the sample across the detector cell.
3-4
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Most oxygen meters are operated by switching the power knob to "ON" with one hand and holding the
oxygen sensor with the other. Once the unit is operating, oxygen molecules diffuse to the sensor, producing a
minute electric current proportional to the oxygen content. The current passes through an electronic circuit, and
the resulting signal is shown as a needle deflection on a meter or as a digital reading.
Despite the rapidity and ease with which oxygen meters can be used, they have limitations such as the
following:
• Because the density of oxygen in the atmosphere depends upon elevation, the meter should be calibrated
at approximately the same elevation at which it is to be used.
• Meters may give incorrect readings in atmospheres with oxygen levels below 19.5% or above 25%.
• The presence of carbon dioxide can shorten the life of the oxygen detector cell significantly.
3.2.2 Monitoring for Exolosivitv
Confined spaces, such as manholes or wet wells, are hazardous environments because they may let gases or
vapors accumulate to explosive levels. For this reason, explosivity monitoring should be a routine part of all
sewer line maintenance. This involves two parameters of concern: the lower explosive limit (LEL) and the upper
explosive limit (UEL). The LEL is the minimum concentration in air at which a gas or vapor will flame with an
ignition source. (Appendix A lists the LELs for some common chemicals.) The UEL is the concentration above
which a gas or vapor concentration is too rich and not enough oxygen is present in the atmosphere to flame.
Atmospheres with concentrations above the UEL may not be explosive, but they are extremely dangerous. Any
sudden change in air flow (opening a door or manhole) can rapidly lower the concentration below the UEL into
the explosive range. These areas should be evacuated, ventilated, and continuously monitored until the
concentration is below the LEL.
Action levels are numeric limits at which actions must be taken to prevent adverse exposure to workplace
hazards. Action levels for explosivity are expressed as a percentage of the LEL. OSHA has set explosivity
action levels as follows:
Percent LEL Action
< 10% Continue operations with caution (respiratory protection if necessary).
10% - 25% Continue operation with extreme caution. Attempt to identify specific
combustible gases or vapors present.
> 25 % (up to UEL) Fire/explosion hazard exists. Leave immediately.
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Explosivity is measured with a combustible gas detector (CGD), also called an explosimeter, which
measures the concentration of combustible gases and vapors in the atmosphere across a hot filament of platinum.
The CGD provides a direct readout of the presence of combustible gases or vapors, expressed as a percentage of
the LEL. For example, a reading of SO % for a gas with a 5 % LEL would indicate that the concentration of the
gas is actually 2.5%.
Like oxygen meters, CGDs are portable and come with built-in pumps that draw samples from the immediate
area or from confined spaces when used with an extension probe. CGDs and oxygen meters typically are
combined in the same unit, so they can be used together (this is necessary since the CGD is not reliable at Q,
concentrations below 19% or above 25%). These units have separate calibration knobs and meter screens.
Like oxygen meters, CGDs screen rapidly but have drawbacks. The CGD must be used in conjunction with
an oxygen meter, as mentioned above. It does not detect potentially explosive dusts or liquid explosives such as
sprays of oil, nor does it work in the presence of silicon-based materials, leaded gasoline, or acids. Vapors and
gases from leaded fuels, halogens, and sulfur compounds will harm the platinum filament contained in the
apparatus, and silicone vapors or gases will destroy the filament altogether. Taking these limitations into account,
the CGD is still a vital tool for ensuring the safety of field personnel, when used in conjunction with an oxygen
meter.
3.2.3 Monitoring for Vapors and Gases
Vapors or gases may build up in sewer lines, at pump stations, or near the point of release around industrial
processes. They may threaten worker health and safety if recommended exposure limits are exceeded and
adequate worker protection is not provided. Workers should not enter high-risk areas unless absolutely
necessary. To ensure that POTW personnel are adequately protected, determine which vapors or gases are
present—and at what concentrations—in the work space and other areas.
Vapor and gas detectors provide a direct readout of either the total concentration of vapors and gases or of
the specific types of contaminants present and their concentrations. The three basic types of vapor and gas
detectors are as follows:
• Photoionization detectors (PIDs);
• Flame ionization detectors (FIDs); and
• Colorimetric indicator tubes.
3-6
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3.2.3.1 Photoionization Detectors
A photoionization detector (PID) uses an ultraviolet light source to ionize a gas and measure its ionization
potential. Ionization potential is the energy required to remove the outermost electron from a molecule. The
ionization potential is specific for any compound or atomic species, and is measured in electron volts (eV). The
presence of an organic vapor causes a positive ionization potential and a current field within the detection
chamber. The detector measures this current and displays the corresponding gas concentration in parts per
million.
Since a PID's ability to detect a chemical depends on its ability to ionize it, the ionization potential of the
chemical to be detected must be compared to the energy generated by the instrument's ultraviolet lamp.
Ultraviolet lamps are available in different energies (such as 8.3, 8.4, 9.5, 10.2, 10.6, 10.9, 11.4, 11.7, and 11.8
eV), and are selected to correspond to the chemical being analyzed and to eliminate the effects of other
atmospheric gases (if the lamp is too energetic, for example, oxygen and nitrogen will ionize and interfere with
the readings).
Consider for example, how a PID would be used to monitor a release of propane (with an ionization
potential of 11.1 eV) and vinyl chloride (10.0 eV). To detect both, both would need to be ionized, and so a lamp
with an 11.1-eV ionization potential would be used. To detect only the vinyl chloride, and prevent interference
from the presence of propane, use a lamp 10.2- or 10.6-eV lamp, which would be strong enough to ionize vinyl
chloride but not propane.
PIDs measure a variety of organic and inorganic gases and vapors, and differ in their analytical capabilities
according to the manufacturer. POTW personnel should contact a scientific equipment supplier for a list of lamps
it carries.
PIDs have several limitations:
• Dust can collect on the lamp and block the transmission of ultraviolet light, reducing the instrument
reading. This problem can be detected during calibration and prevented through regular lamp cleaning.
• Humidity can cause condensation on the lamp and reduce the available light, lowering the validity of the
reading.
• Radio-frequency interference from pulsed DC or AC power lines, transformers, generators, and radio
wave transmission may produce an error in response.
• The validity of the readings will lower as the lamp ages.
• PIDs cannot measure methane.
Pollutant levels detected with the PID should be compared against their corresponding action levels, such as
the threshold limit values (TLVs) discussed in Chapter 4. If a pollutant is detected at or near the TLV or other
3-7
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action level, the POTW inspector should evacuate the area and take appropriate action to identify the source. If
it is necessary to enter the area, use the appropriate personnel protection equipment (e.g., respirator with
appropriate filter).
3.2.3.2 Flame lonization Detectors
Flame ionization detectors (FIDs) work on the principle of hydrogen flame ionization. A flame ionizes the
organic vapors, resulting in a current that is measured and displayed on a readout in parts per million.
The organic vapor analyzer (OVA) is the most commonly used FID, particularly because it has a chemically-
resistant sampling system and can be calibrated to almost all organic vapors, measuring gas concentrations
accurately in the O-to-10 ppm, O-to-100 ppm, and O-to-1000 ppm ranges. As with the PID, levels detected by the
OVA should be compared to action levels such as TLVs. An alarm can be set to sound if the preset concentration
level (usually one-half the TLV) is met or exceeded.
The OVA operates in either of two modes. In survey mode it monitors continuously for all detectable
organic vapors. In gas chromatograph (GO mode, air samples are drawn and injected into the system, and the
user determines the identities and concentrations of specific organic vapors and gases relative to the methane
response of the OVA. The OVA is most sensitive to hydrocarbons but its response varies for other chemicals.
When specific compounds are to be tested, the OVA operator needs to know the capability of the OVA for the
compounds. An inquiry of the manufacturer, a review of the literature, and a continuing calibration/verification
program are necessary.
OVAs and other FIDs have some disadvantages:
• They do not detect inorganic gases and vapors, or some synthetics.
• They should not be used at temperatures below 4.5*C (40'F).
• Readings can only be reported relative to the calibration standard used.
3.2.3.3 Colorimetric Tubes
A colorimetric indicator tube measures the concentration of a specific gas by drawing an air stream of a
known volume through a calibrated glass tube filled with an indicator chemical. If the gas of concern is present,
it will react with the indicator chemical by staining or changing the color of the tube. The concentration of the
gas or vapor is then read off the markings on the calibrated tube and compared to the appropriate TLV or other
action level.
3-8
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Colorimetric tubes have certain advantages:
• They are easy to use in the Held.
• Detector tubes are available for gases that are not detected by the OVA.
• Tubes are available for gases which will "poison" the filament of an explosimeter and oxygen meter
indicator, such as hydrogen sulfide, sulfur dioxide, sulfur trioxide, hydrogen chloride hydrogen cyanide,
and chlorine.
Colorimetric tubes have certain disadvantages:
• They break easily.
• A different type of tube is needed for each specific gas or vapor, which could become costly.
• Interference with other chemicals can alter the accuracy of the tubes ±25%.
In addition, instructions vary for different tubes. For example, one chemical could require one pump to
draw an air stream into the tube, while another chemical could require two. Also, the time required for color
change varies with the manufacturer. POTW personnel must therefore closely follow the instructions for each
tube.
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4. SCREENING INDUSTRIAL DISCHARGES
Chapter 3 discussed instruments and tools that POTW personnel can use to detect the presence of reactive and
gas/vapor-toxic substances. This chapter presents two methods for identifying wastewaters that may create
gas/vapor-toxic conditions and require preventive controls. Section 4.1 describes how to use gas/vapor-toxicity
criteria to calculate concentration-based screening levels. Section 4.2 discusses an alternative approach taken by
the Cincinnati Metropolitan Sanitary District (CMSD).
4.1 DEVELOPING WASTEWATER SCREENING LEVELS BASED ON GAS/VAPOR TOXICITY
POTW personnel can determine whether a discharge may generate gas/vapor-toxic conditions by comparing
gas/vapor toxicity criteria to pollutant concentrations in the industry's discharge. This involves three steps:
• Identifying the relevant gas/vapor toxicity criteria;
• Converting the gas/vapor toxicity criteria to wastewater screening levels; and
• Comparing the wastewater screening levels to current discharge levels.
4.1.1 Step 1: Identify Gas/Vapor Toxicity Criteria
This manual recommends gas/vapor-toxicity criteria based on occupational guidelines that have been
developed by the American Conference of Governmental Industrial Hygienists (ACGIH) and used by the
Occupational Health and Safety Administration (OSHA) and the National Institute for Occupational Safety and
Health (NIOSH). The guidelines establish air contaminant exposure limits above which the "average worker"
should not be exposed, assuming that an "average worker":
• Is exposed to the substance throughout his/her entire occupational lifetime — between the ages of 18 and
65;
• Works a 40-hour work week;
• Weighs 70 kilograms (154.7 pounds);
• Is healthy with no prior physical or health deficiencies;
• Is not employed in a specific industry;
• Absorbs a certain percentage of the substance in his/her body and excretes or detoxifies the remainder;
• Has a normal respiration rate; and
• Varies in susceptibility according to physical condition (including pregnancy, stress, and lack of sleep)
and lifestyle (such as alcohol or drug use, long work hours, or heavy exertion).
4-1
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A threshold limit value (TLV) is the airborne concentration of a particular substance to which the average
worker may be exposed without adverse effect. ACGIH publishes an annual list of TLVs for approximately 650
toxic substances. Its publication, "Threshold Limit Values and Biological Exposure Indices," is a convenient
reference source for POTW personnel.1 TLVs are based on the best available information from past industrial
experiences, animal exposure studies, and documented worker reactions. ACGIH designates three categories of
TLVs2:
• Threshold limit value/time-weighted average (TLV-TWA) is the average airborne concentration of a
substance not to be exceeded in any 8-hour work shift of a 40-hour work week without causing any
adverse health effects. The TLV-TWA is a chronic limit.
• Threshold limit value/short-term exposure limit (TLV-STELI is the 15-minute time-weighted average
exposure not to be exceeded during a work day without causing:
— Irritation;
— Permanent tissue damage; or
— Narcosis (sleepiness) that may increase the chances of injury, lower the chances of self-rescue, or
reduce work efficiency.
Exposures at the TLV-STEL are limited to 4 times a day, with each exposure lasting less than IS minutes
and at least 1 hour between successive TLV-STEL exposures. The TLV-STEL is an acute limit, and is
set at a value higher than the TLV-TWA to allow for excursions.
• Threshold limit value-ceiling (TLV-Q is the airborne concentration that may not be exceeded during any
part of the work day. The TLV-C is an acute limit.
Table 4-1 lists current TLVs for some gas/vapor-toxic pollutants that are common in industrial waste waters.
TLVs can be used to set exposure levels for POTW workers and to identify the degree of protection needed when
designing engineering controls for high-risk areas at the POTW. This manual uses chronic TLVs (TLV-TWA),
which mostly are lower than acute TLVs (TLV-STEL). Using chronic TLVs to set screening levels will ensure
that acute TLVs are also being addressed and acute health and safety problems avoided.
Exposure limits are developed for individual chemicals. For exposure to a mixture of two or more
compounds, ACGIH has developed formulas to calculate adjusted TLVs for combined exposure effects. This
approach, which assumes additive toxicity among the components of a mixture, is also used by OSHA. It is
discussed in greater detail in Section 4.1.4.
'"Threshold Limit Values and Biological Exposure Indices," American Conference of Governmental Industrial
Hygienists, Cincinnati, OH. To order the published list, send requests to ACGIH, 6500 Glenway Ave., Bldg. D-7,
Cincinnati, OH, 45211-4438.
2 These definitions are paraphrased from ACGIH TLV booklets. The verbatim definitions can be found in the
glossary in Appendix K.
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TABLE 4-1. SOME GAS/VAPOR-TOXIC POLLUTANTS WITH THEIR RESPECTIVE
THRESHOLD LIMIT VALUES (TLVs)
CHEMICAL COMPOUND
Acrolein
Acrylonitrile
Ammonia
Benzene
Bromoform
Carbon dioxide
Carbon tetrachloride
Chlorobenzene
Chloroform
Chlorine
1 , 1 -Dichloroethane
1 ,2-Dichloropropane
Ethyl benzene
Hydrogen sulfide
Methyl bromide
Methyl chloride
Methylene chloride
1 , 1 ,2,2-Tetrachloroethane
Tetrachloroethylene
1 , 1 ,2-Trichloroethane
1,1,1 -Trichloroethane
Trichloroethylene
Vinyl chloride
Toluene
ACGIH TLV (1990-1991)
0.1
2
25
10
0.5
5000
5
75
10
0.5
200
75
100
10
5
50
50
1
50
10
350
50
5
100
ppm-TWA*
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
ppm-TWA
Source: Threshold Limit Values and Biological Exposure Indices for 1990-1991,
Governmental Industrial Hygienists, 1990.
TWA - Time Weighted Average
**STEL - Short Term Exposure Limit
0.3
35
30000
1
250
110
125
15
100
200
450
200
150
ppm-STEL**
ppm-STEL
ppm-STEL
ppm-STEL
ppm-STEL
ppm-STEL
ppm-STEL
ppm-STEL
ppm-STEL
ppm-STEL
ppm-STEL
ppm-STEL
ppm-STEL
American Conference of
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4.1.2 Step 2: Convert Gas/Vapor Toxicitv Criteria to Wastewater Screening Levels
POTW personnel may use an air monitoring device, such as those discussed in Chapter 3, to measure air
concentrations directly and compare pollutant concentration to TLVs. More commonly, however, POTW
personnel will have information on the concentration of pollutants in the wastewater and require some means of
comparing the wastewater concentration to the air concentration TLVs. This section discusses how to use
gas/vapor toxicity criteria for air contaminants to develop screening levels for pollutants in wastewater.
Conversion of air criteria to water criteria requires an understanding of volatilization—the conversion to a gas or
vapor of any substance that ordinarily is liquid or solid. Volatilization of a chemical from a water solution is
driven by the chemical's vapor pressure and water solubility.
Vapor pressure. Vapor pressure is the pressure a gas exerts on the walls of a closed container. For
example, if a liquid such as benzene partially fills a closed container, benzene molecules will evaporate from the
liquid surface. Because the container is closed, some of the benzene molecules in the headspace above the liquid
will return to the liquid by condensation. When the volatilization rate equals the condensation rate, vapor-liquid
equilibrium is attained, and the benzene molecules in the headspace exert the vapor pressure of benzene on the
walls of the container. The concentration of benzene in the headspace can be determined from this vapor
pressure. Vapor pressure varies with temperature.
Water solubility. The water solubility of a chemical is the concentration of that chemical in water above
which the chemical forms a separate liquid, solid, or gaseous phase. Water solubility is also a function of
temperature.
With these definitions in mind, consider a volatile chemical discharged in wastewater to a sewer line. In the
sewer line, some of the chemical molecules will volatilize and enter the headspace. Because the headspace is
confined, some of the molecules in the headspace will, at the same time, condense and return to the wastewater.
In this way the sewer line can be thought of as a confined space. Over a sufficient residence time, each
wastewater constituent will volatilize to the extent determined by that constituent's vapor-liquid equilibrium
relationship.
4-4
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For many slightly- to moderately-soluble chemicals, this equilibrium is closely approximated by Henry's
Law, a general thermodynamic relationship that can apply to sewer conditions. Henry's Law states that, in a
closed system, the concentration of the constituent in the vapor phase and the corresponding equilibrium
concentration in the liquid phase are related by a constant. This constant, the Henry's Law constant, is the ratio
of the constituent's vapor pressure to its water solubility:
H = P^/S
where:
H = constituent's Henry's Law constant, in atm mVmol
P,^, = constituent's vapor pressure, in atm
S = constituent's water solubility, in mol/m3
A chemical's Henry's Law constant determines how much it will volatilize. Every chemical has a unique
Henry's Law constant.
This manual makes some simplifying assumptions about the applicability of Henry's Law constants to
conditions in a sewer line:
• Temperature. Although the Henry's Law constant is affected by the temperature in the sewer line, this
manual assumes that the wastewater and sewer headspace temperatures do not deviate significantly from
25°C. Where process discharges are known to contain pollutants of concern at higher temperatures, the
POTW should not rely on the development of screening criteria, but require the industrial user to provide
site-specific wastewater and headspace monitoring data.
• Other constituents. Although the Henry's Law constant is affected by the presence of other constituents
in the wastewater, this manual assumes that other constituents have no effect.
• Air flow. The Henry's Law constant is affected by the rate of air flow through the sewer line. If the air
flow rate is high enough, wastewater will be continuously exposed to fresh air and volatile constituents
will be constantly carried off. Furthermore, equilibrium will not be reached and the concentrations of the
constituents in the headspace and wastewater will remain low. Conversely, if the air flow rate is
negligible, volatile constituents can accumulate in the sewer headspace and the resulting air and
wastewater concentrations in the sewer line will be higher. The screening approach discussed here
conservatively assumes that air flow is negligible.
• Rate of volatilization. Volatilization rate is affected by a number of complex and site-specific factors
such as the temperature in the sewer line, the wastewater surface area, the air flow rate through the sewer
line, the turbulence of wastewater mixing, and the wastewater residence time in the sewer line. This
manual assumes instantaneous attainment of vapor-liquid equilibrium and does not consider volatilization
rates.
With these simplifying assumptions, Henry's Law constants can be used to set wastewater screening levels
and for evaluating the wastewater's potential to generate gas/vapor-toxic atmospheres. To convert an air criterion
(the TLV-TWA) for a gas/vapor-toxic chemical into a corresponding wastewater screening level, the TLV is
divided by the chemical's Henry's Law constant and then multiplied by appropriate conversion factors. Table 4-2
4-5
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lists some wastewater screening levels for common gas/vapor-toxic chemicals. Appendix B summarizes the
gas/vapor toxic screening procedure and lists additional screening levels. This procedure is also presented in
detail in EPA's Guidance Manual on the Development and Implementation of Local Discharge Limitations Under
the Pretreatment Program (December, 1987).
4.1.3 Step 3: Compare Wastewater Screening Levels to Current Discharge Levels
Once the POTW personnel set a wastewater screening level for a gas/vapor-toxic compound, the screening
level should be compared to the concentration actually being discharged by the industrial user. A discharge that
exceeds its screening level should be considered potentially gas/vapor-toxic.
4.1.4 Screening for Gas/Vapor-Toxic Mixtures
As mentioned earlier, TLVs are chemical-specific and do not readily account for the combined toxicity of a
mixture of chemicals in air. One way to estimate the toxicity of a chemical mixture is to assume that its toxicity
is equivalent to the sum of the individual toxicities of its components. Appendix B outlines a procedure in which
a mixture's potential gas/vapor toxicity is determined in this manner. Unfortunately, for complex mixtures of
chemicals, this procedure may be both cumbersome (screening levels must be obtained for all potentially
gas/vapor-toxic constituents of the discharge) and inexact (it simplistically assumes additive toxicity).3
4.1.5 Screening for Reactivity
The reactivity prohibition [40 CFR 403.5(b)(l)] defined reactive pollutants to include wastestreams with a
closed-cup flashpoint less than 140 *F or 60* C. Unlike the prohibition of gas/vapor-toxic pollutants, compliance
with the flashpoint condition can be directly measured in the industrial user's wastestream. Direct measurement
is the easiest method for determining compliance with flashpoint condition of this mandatory prohibition. The
approved test methods are specified in 40 CFR 261.21.
If further screening is needed, wastewaters which may create reactivity hazards can be identified by screening
levels developed using the LEL as an indicator of reactivity. The screening level is calculated by dividing 10% of
a chemical's LEL by its Henry's Law constant and multiplying by appropriate conversion factors. This
procedure is described in Appendix C of this manual and in the Guidance Manual on the Development and
Implementation of Local Discharge Limitations Under the Pretreatment Program (December, 1987). Table 4-2
presents screening levels for flammable or explosive priority pollutants for which criteria exist, as well as other
industrial pollutants. The use of LEL-based screening levels should complement, rather than replace, field
measurements of LEL, which are an important part of field safety procedures.
'Many chemicals, in fact, show synergistic behavior, in which the presence of one chemical enhances the
toxicity of another, or antagonistic behavior, in which the presence of one chemical detracts from the toxicity of
another. Synergistic and antagonistic behavior are chemical-specific and, therefore, are not addressed by the generic
screening procedure discussed here.
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TABLE 4-2. DISCHARGE SCREENING LEVELS BASED ON GAS/VAPOR TOXICJTY
ANDEXPLOSIVITY
Compound
Acrylonitrile
Benzene
Bromomethane
Carbon disulfide
Carbon tetrachloride
Chlorobenzene
Chloroethane
Chloroform
Chloromethane
1 ,2-Dichlorobenzene
1 ,4-Dichlorobenzene
Dichlorodifluoromethane
1,1-Dichloroethane
trans- 1 ,2-Dichloroethylene
1 ,2-Dichloropropane
1 ,3-Dichloropropene
Ethyl benzene
Ethylene dichloride
Formaldehyde
Heptachlor
Hexachloro-1,3 butadiene
Hexachloroethane
Methyl ethyl ketone
Methylene chloride
Napthalene
Nitrobenzene
Tetrachloroethylene
Toluene
1 ,2,4-Trichlorobenzene
1,1,1 -Trichloroethane
Trichloroethylene
Trichlorofluoromethane
Vinyl chloride
Vinylidene chloride
Aroclor 1242
Aroclor 1254
Gas/Vapor Toxicity
Screening Level
(mg/1)
1.19
0.13
0.002
0.06
0.03
2.31
5.73
0.41
0.29
3.75
3.55
0.04
4.58
0.28
3.62
0.08
1.59
1.05
0.06
0.003
0.0002
0.93
249
2.06
*
*
0.53
1.36
0.39
1.55
0.71
1.23
0.004
0.003
0.01
0.005
Explosivity Screening Level
(mg/l)
(Based on 10% of the LEL)
1794
20
4.7
6.3
*
40
1.6
M
1.1
165
104
*
128
14
164
435
16
660
412
«
*
*
2486
494
240
17046
a
17
197
33
114
m
2.2
3.3
»
*
* Criteria for these compounds nave not yet been developed.
4-7
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4.2 CINCINNATI METROPOLITAN SANITARY DISTRICT (CMSD) SCREENING PROCEDURE
In February 1981, six workers excavating a collapsed sewer at the Cincinnati Metropolitan Sanitary District
(CMSD) reported experiencing eye and nose irritation, nausea, dizziness, and vomiting. NIOSH tested the sewer
air spaces and identified 1,1,1-trichloroethane, naphtha, toluene, and other solvents — many of which were above
the TLV-TWA values.4 In another 1981 incident, CMSD requested a NIOSH investigation because organic
vapors were detected near the bar screen area at one of the treatment plants and workers complained of breathing
difficulties and eyes and nose irritation. Numerous organic compounds were detected near the headworks; one
sewer airspace contained potentially explosive concentrations of hexane and at least two sewer airspaces contained
levels of volatile compounds classified as immediately dangerous to life and health (IDLH)5 for persons entering
those areas. NIOSH found that routine activities could expose employees to a multitude of chemicals including
toluene, xylene, aliphatic naphtha, 1,1,1-trichloroethane, trichloroethylene, chlorobenzene, o-chlorotoluene, and
trichlorobenzene.
To address these problems, CMSD, in consultation with NIOSH, developed a generic discharge screening
technique designed to identify the presence of explosive and gas/vapor-toxic compounds. The technique
compares the discharge concentration of total volatile organics to a 300-ppm hexane equivalent limit. This limit
was deemed to sufficient to protect the collection system from fires and explosions and to provide workers
minimal protection from gas/vapor-toxic pollutants. Exceedances indicate a potentially gas/vapor-toxic or
explosive discharge warranting additional investigation.
Under the CMSD monitoring procedure, the POTW staff:
• Collects an industrial user discharge sample in accordance with proper volatile organic sampling
techniques (e.g., zero headspace);
• Withdraws 50% of the sample by volume, followed by injection of nitrogen gas to maintain one
atmosphere total pressure;
• Equilibrates the sample (as explained in Appendix D);
• Analyzes the sample's headspace using gas chromatography/mass spectrometry (GC/MS);
• Expresses the headspace concentration of total volatile organics as an equivalent concentration of hexane;
and
• Compares the headspace concentration of total volatile organics to the 300-ppm hexane limit.
4Source: Health Hazard Evaluation Report, HETA 81-207-945 (1981) NIOSH.
3IDLH - Maximum level from which one could escape within 30 minutes without any escape-impairing
symptoms or irreversible health effects.
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The 300-ppm hexane equivalent limit was developed by CMSD to provide its POTW workers exposed to
sewer atmospheres at least minimal protection from gas/vapor toxicity. CMSD concluded that below the
300-ppm limit, carbon filters will generally protect POTW workers adequately. The validity of this conclusion
depends on which chemicals are of concern at a particular site. Wastewater and headspace analysis for specific
volatile organic pollutants should be conducted before implementing the CMSD method. EPA's Technology
Assessment Branch Wastewater Research Division, reviewed the NIOSH/CMSD documentation and noted that
the limit is not chemical-specific and therefore does not ensure ACGIH or OSHA exposure limits will be met in
the sewer or POTW atmosphere. EPA also concluded that CMSD's 300-ppm hexane equivalent limit does not
apply to toxic vapors from spills, to generation of hydrogen sulfide or methane gas in sewers, or to vapor purging
of oxygen from sewers, all of which represent significant health hazards.6
Initial screening by the CMSD approach can be used to identify discharges warranting detailed chemical-
specific screening by the method discussed in Section S.I or, if the contributing source(s) of volatile organics are
clear, to begin immediate mitigation.
Appendix D describes the CMSD screening methodology in more detail.
* Guidance Manual on the Development and Implementation of Local Discharge Limitations Under the
Pretreatment Program (December 1987), USEPA.
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5. PROBLEM IDENTIFICATION PROCESS
Chapters 5 and 6 discuss a three-phase process by which the POTW, using the information and tools
presented in Chapters 3 and 4, can identify and begin to mitigate reactive and gas/vapor-toxic hazards. As
Figure 5-1 illustrates, the process consists of three phases:
• Phase 1: Collect Information
• Phase 2: Perform Hazards Analysis
• Phase 3: Select Mitigation Measures.
This chapter discusses the first two phases. Chapter 6 discusses Phase 3 and explores the preventive options
available to the POTW.
Hazards facing POTW workers vary in complexity. This chapter focuses on the more complex problems to
ensure that the subject matter receives adequate coverage. If a POTW faces problems that are more obvious or
simple than those described here, it should follow the same principles—even if it actually performs procedures
that are less rigorous.
5.1 PHASE 1: COLLECT INFORMATION
In this phase the POTW should review available data and conduct all necessary inspections of local
industries, the collection system, and the treatment plant.
5.1.1 Identify Data Collection Needs
As the problem identification process begins, the POTW team first should define the overall objectives of the
problem identification process. The POTW may wish to investigate how to reduce concentrations of specific
chemicals in an industrial user's discharge because of potential gas/vapor toxicity problems, or investigate
whether to require best management practices (BMPs) at an industrial user to protect POTW workers. (BMPs
may include activities such as good housekeeping measures, waste segregation plans, and staff training.) All
POTW employees who will collect and use data should be involved at the beginning of the process to ensure that
their data collection goals are similar and that efforts will not be duplicated.
5-1
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Identify Data Collection
Needs
Conduct File Review
Phase I
Collect
Information
Identify
Inspection/Sampling Goals
Perform
I nspection/Sampling
Are Data Needs
Satisfied?
Yes
_L
Evaluate IU Management
Practices
Establish Discharge
Screening Criteria
Phase 2
Perform Hazards
Analysis
Perform Screening
Exclude IU from
Further
Consideration
Does IU Fail
Screening Criteria?
List of lUs with Poor
Management
Practices
List of I Us Failing
Screening Criteria
Phase 3
Select Hazard
Mitigation
Measures
Evaluate Hazard Mitigation
Options
Adopt Hazard Mitigation
Measures
FIGURE 5-1. PROBLEM IDENTIFICATION PROCESS
5-2
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Once the POTW team has identified the problem areas, it should identify the types of data necessary to
support each decision-making process. For example, if the POTW team was investigating the need for BMPs to
protect inspectors at a particular industrial user, it would seek the following types of data:
• Which chemicals are stored at the facility, and in what concentrations;
• How and where the chemicals are used and, correspondingly, how and where release or exposure might
occur; and
• Which hazards are associated with exposure to the chemicals.
The POTW should develop criteria to ensure that these data are of sufficient quantity and quality. For the
BMP example above, this would mean the following:
• Because the chemical inventory must be both complete and accurate in order to identify potential hazards,
it should be reviewed by both POTW and industry personnel at the beginning of the inspection, updated
as the inspector tours the facility, and checked again by industry officials at the end of the inspection.
• Pollutant concentration data must be representative because they are the basis for evaluating hazards.
Where chemical concentrations fluctuate, the POTW must decide whether to collect a large body of data
in order to account for slugs and other fluctuations.
• The manner and location of chemical handling (storage, transfer, use, treatment and disposal) must be
based on recent information, since the POTW inspector cannot guarantee that results from an inspection
conducted a year ago are accurate or up-to-date. The inspector should update chemical handling
information regularly through discussions with industry personnel and a comprehensive plant tour.
The POTW should locate its industry files, reference documents, and contacts with the fire department and
other knowledgeable municipal agencies, to facilitate this phase of the problem identification process.
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5.1.2 Perform File Reviews
The POTW should review all in-house files on each industrial user of concern to obtain necessary
background information before a site inspection. The POTW should review the following data sources on the
industry:
• Discharge permit application and supporting files;
• Sewer connection application and supporting files;
• Inspection reports;
• Discharge sampling data;
• Building permit applications;
• Sewer maps;
• Sewer maintenance reports;
• Fire department records about chemical usage;
• Material safety data sheets (MSDSs);
• Citizen complaints;
• "Form R" reports submitted under the Emergency Planning and Community Right-to-Know Act (SARA
Title III); and
• Notifications of hazardous waste discharges from the industrial user, as required under 40 CFR
403.12(p).
The POTW staff can also contact local OSHA offices to determine whether any complaints have been lodged
against the industry, whether OSHA inspections have occurred, and the results of any such inspections.
The POTW should summarize the file review information on an Information Collection/Decision sheet. A
blank copy of this form is provided in Appendix F; Figure 5-2 provides an example of a sheet that has been filled
out.
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1. STATE THE PURPOSE OF THE INFORMATION COLLECTION (e.g., response to worker health
and safety concerns) This information collection activity is being undertaken in response to
inspector concerns regarding noxious gases and vapors at XYZ Industries process line No. 3. The
inspector has concerns that the discharge from the industry mav affect the collection system
maintenance crew. The data collected will determine the source of the gases and vapors.
characterize the extent ftf hazard, and identify safety equipment and controls that mav be
appropriate.
2. CHECK THE EVALUATIONS THAT MUST BE UNDERTAKEN
[/] Chemical Inventory
a. Indicate the type of data needed: Inventory of all chemicals used or stored in the area north of
process line No. 3.
b. What are the potential sources of data: XYZ permit application and file, past inspector notes.
Reviewed both sources of information; information is 3 years old.
c. List specific needs relating to use of the data: Data needs to be current (within the last year.)
Determination of Chemical Characteristics at Process Lines
a. Indicate the type of data needed: Need a characterization of chemicals and chemical hazards
relating to process line No. 1. (This is an open series of tanks and channels.)
b. What are the potential sources of data: 1. No information on process characteristics on file.
Calls to XYZ have been unproductive. 2. Hazard evaluation can be accomplished using
ACGIH reference manual. MSDSS. Dangerous Properties of Industrial Materials (Sax), and
discharge permit application.
c. List specific needs relating to use of the data: Need to obtain detailed, current data (within the
oast vear).
[/] Identification of Chemical Release Points
a. Indicate the type of data needed: N/A
b. What are the potential sources of data: N/A
c. List specific needs relating to use of the data: N/A
FIGURE 5-2. SAMPLE INFORMATION COLLECTION/DECISION SHEET
5-5
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[/] Evaluation of Controls/Mitigative Measures
a. Indicate the type of data needed: Inspection reports indicate exhaust hoods above process line.
Unclear whether the exhaust hoods work.
b. What are the potential sources of data: Contact plant foreman regarding operation and
maintenance aspects.
c. List specific needs relating to use of the data: None.
[ ] Other, explain:
a. Indicate the type of data needed:
b. What are the potential sources of data:
c. List specific needs relating to use of the data:
[S] Identification of Appropriate Safety Protocols for Future Inspections or Collection System Work
Delay on-site investigation pending receipt and analysis of data from XYZ on chemical
characteristics and concentration.
Discuss health and safety concerns with XYZ staff in light of process chemical characterization
data.
FIGURE 5-2. SAMPLE INFORMATION COLLECTION/DECISION SHEET (Continued)
5-6
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3. IDENTIFY SPECIFIC DATA NEEDS TO BE MET BY FACILITY INSPECTION/SAMPLING AND
DESIGN INFORMATION COLLECTION PROTOCOL
Need to verify that existing information on processes are up-to-date, that chemical usage is as
permitted, and request data regarding the chemical composition of solutions in tanks P-3-1 and P-3-
2. If data received are not adequate, request XYZ design a program of grab sampling to verify
the constituents and concentrations present. Information obtained to date indicate that the
characteristics of the wastewater are fairly constant and that grab samples will provide an adequate
representation of the wastewaters.
Additional Comments:
Completed by: Date:
FIGURE 5-2. SAMPLE INFORMATION COLLECTION/DECISION SHEET (Continued)
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5.1.3 Conduct Inspections and Field Evaluations
After the file review, the POTW should know exactly what information it still needs to collect and how to
collect it. An industry inspection will then be useful for evaluating (or verifying) the inventory of chemical
management practices at the industry and identifying potential reactivity and gas/vapor toxicity hazards on site.
The rest of this section discusses how to conduct a chemical management practices inspection and a field
evaluation of reactivity and gas/vapor toxicity hazards. Although they are discussed separately here, the two
inspections can be performed together.
5.1.3.1 Develop an Inventory of Chemical Management Practices
The POTW should conduct an on-site assessment of an industry's chemical management practices for two
reasons: (1) to ensure that the information collected during the file review is complete and accurate; and (2) to
identify and evaluate first-hand any hazards to which a POTW inspector might be exposed.
Preparing for the chemical management practices inspection
Before the inspection, the inspector should obtain or draw a map showing areas in the facility that should be
examined during the inspection. These areas would include all chemical management locations, such as:
• Chemical storage areas;
• Chemical transfer areas;
• In-process chemical usage areas;
• Waste generation areas; and
• Treatment and storage areas for wastes and waste waters.
The inspector should make lists of all chemicals expected to be found in each of these areas, including notes
on chemicals posing reactivity (e.g., because of incompatibility), gas/vapor toxicity, or other hazards. (A list of
the volatile organic priority pollutants is in Appendix E.) Figure 5-3, a facility hazard summary sheet, can be
used to summarize this information. A copy of this sheet should be kept in the industry files and updated during
subsequent inspections.
5-8
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THE FOLLOWING NOTES ARE KEYED TO DESIGNATED AREAS ON THE FACILITY MAP
[ATTACHED]. Inspectors should update this sheet and the attached map after each visit to the industry.
This sheet should be reviewed prior to each inspection and the safety equipment used should reflect the
potential hazards listed on this sheet.
FACILITY AREA
2_
3
5_
6
CHEMICAL HAZARD
[O] [C] [F] [E]
[ ] [ 1 [ J [ ]
[ ] [ ] [ J [ ]
[ ] [ ] [ 1 [ ]
[ ] [ 1 [ 1 [ ]
[ 1 [ 1 [ ] [ 1
PHYSICAL HAZARD
[S] [C] [H] [O] [A] [N]
[ ] [ I [ 1 [ 1 [ 1 [ 1
[ ] t ] [ 1 [ 1 [ ] [ 1
[ 1 [ ] [ ] [ ] [ 1 [ ]
[ 1 [ ] [ 1 [ ] [ ] [ ]
[ ] [ ] [ 1 [ 1 [ ] [ 1
[ ] [ ] [ 1 [ 1 [ 1 [ ]
Chemical hazards
[O]
[C]
[F]
[E]
NOTES:
Strong oxidant
Corrosive
Fume toxic
Explosive
Physical Hazards
[S] = Splash and spill hazards
[C] = Construction area
[H] = Heavy machinery area
[O] = Open tanks and/or channels
[A] = Aerosols/fumes
[N] = High noise area
INSPECTION LOG
DATE
NAME
DATE
NAME
FIGURE 5-3. SAMPLE FACILITY HAZARD SUMMARY SHEET
5-9
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Conducting the chemical management practices inspection
Before touring the industrial facility, the inspector should verify the completeness and accuracy of the map
and the chemical list with facility personnel. The inspector should make any corrections necessary, but should
not delete information from the list without first-hand confirmation (for example, if a change in plant processes
has resulted in the use of different feed stocks, the inspector should not assume that all of the previously-used
chemicals have been removed from the site). Facility staff should be asked to identify all known plant hazards, to
evaluate potential hazards identified by the inspector, and to describe the safety equipment used and precautions
followed at the facility.
After ensuring that he or she is carrying the correct monitoring instruments and using necessary safety
equipment and clothing, the inspector should tour each chemical management area, giving particular attention to:
• Storage, use, or generation of potentially gas/vapor-toxic chemicals, potential accumulation of vapors or
gases within the storage area, work area, and sampling locations, and the presence of adequate ventilation
(important when considering the need for protective equipment and industry BMPs).
• Storage, use, or generation of reactive or incompatible chemicals.
• Discovery of chemicals not previously identified.
• Identifying, and gathering complete information on the existence of chemical management areas not
previously identified.
• Proximity of incompatible pollutants to each other.
• Potential for direct contact with chemicals or wastes during an inspection (which may suggest a need for
protective equipment).
• Physical condition and manner of operation of chemical storage/reaction/treatment vessels, and Ihe
potential for spills or catastrophic failure (which may suggest a need for BMPs).
• Visual evidence of reactive, particularly corrosive, chemicals. In extreme cases, the presence of salt
deposits will reveal corrosive activity (strong bases react with carbon dioxide in air to form salts, for
example).
• Proximity of floor drains to chemical management areas (for later use in evaluating the need for BMPs).
The inspector should take detailed notes on each of these points to best assess the potential hazards and make
an informed selection of a industrial user hazard management plan (discussed in Chapter 6). The facility hazard
summary sheet should be updated after the inspection.
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5.1.3.2 Field Evaluation of Reactivity and Gas/Vapor Toxicity Information
A field evaluation of potential reactivity and gas/vapor toxicity hazards will enable the POTW to:
• Identify open wastewater conveyances and mixing areas within the industrial facility (as opposed to
process and product areas identified through the inspection process described above). These areas are
lilrp.lv release nnints for volatile, nnllutants
f f G
likely release points for volatile pollutants.
• Understand the variability of the effluent data used in screening exercises. This is important since the
POTW may wish to protect against the highest concentrations of a pollutant detected, rather than the
average or "representative" concentrations.
The POTW staff can accomplish these goals in a single inspection, since both require evaluation of the sources
and flow of wastewaters and the variations in pollutant concentrations.
Preparing for the Field Evaluation of Reactivity and Gas/Vapor Toxicitv Information
The inspector should obtain a detailed sewer map and flow diagrams for all industrial processes that
contribute to the total wastewater flow. The flow diagrams should show all wastewater sources (including
process blowdown and overflows, where applicable), sumps, floor drains, open tanks, treatment processes, and
connections to both sanitary and storm sewers.
To ensure that all sources are accounted for, the inspector should perform a water balance for both peak
operating periods and production down-times. The inspector should characterize each wastewater source as
completely as possible—including the pollutants present and their concentrations—and highlight wastewaters with
incompatible characteristics or the potential to cause gas/vapor toxicity problems. The inspector's review of the
flow diagram and water balance should focus on:
• Specific wastestreams within the plant that should be kept separate to prevent the generation of toxic
vapors and gases (such as wastestreams containing hydrogen cyanide or sulfide or with pH < 2 or
> 12);
• Combined wastestreams with pollutant concentrations that might contribute to a gas/vapor toxicity or
reactivity problem, and possible release pathways; and
• The adequacy of wastewater source information, as reflected by the water balances.
At this time the inspector also should obtain any additional flow information necessary to complete the water
balance. The water balance should appear reasonable (including consideration of evaporation losses); the
inspector should ask facility engineers for an explanation of discrepancies greater than 10%. The inspector
should also ask for plant operating information that will show whether seasonal shut-downs, equipment failures,
or emergency conditions might result in the re-routing of wastewaters (for example, tank overflows might be
directed to emergency storage sumps in the event of a pump failure).
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FOR EACH OUTFALL TO THE SEWER, PROVIDE THE FOLLOWING INFORMATION:
A. FACILITY:
OUTFALL NO:
OUTFALL LOCATION:
B. WATER SOURCE: [Include method of estimation (e.g., water meter)]
City Water: gpd
Private wells: gpd
Other: gpd
Total: gpd
C. WATER USAGE (Identify water usage and indicate flow):
Process waters:
1. flow: gpd
2. flow: gpd
3. flow: gpd
4. flow: gpd
Noncontact cooling water:
1. flow: gpd
2. flow: gpd
Domestic uses:
1. flow: gpd
2. flow: gpd
Total usage: gpd
D. STORM WATER (Provide numbers if flows are directed to the sewer):
1. Roof Drains flow: gpd
2. Drainage/Runoff flow: gpd
Total flow: gpd
Compare totals from parts B and C above. These two values should agree to within 10% and be reasonable
when compared to measured/observed flows from the facility.
FIGURE 5-4. SAMPLE WATER BALANCE WORKSHEET
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Conducting the Field Evaluation of Reactivity and Gas/Vapor Toxicitv Information
Before the field evaluation, the POTW inspector should review the facility maps and chemical lists with
facility personnel and correct any inaccuracies. This will ensure the best possible characterization of in-plant
wastestreams and points of potential exposure.
At this time the inspector also should obtain any additional flow information necessary to complete the water
balance. The water balance should appear reasonable (including consideration of evaporation losses); the
inspector should ask facility engineers for an explanation of discrepancies greater than 10%. The inspector
should also ask for plant operating information that will show whether seasonal shut-downs, equipment failures,
or emergency conditions might result in the re-routing of wastewaters (for example, tank overflows might be
directed to emergency storage sumps in the event of a pump failure).
The field evaluation should consist primarily of a plant tour. During the plant tour the inspector should:
• Note characteristics of wastewaters mixing in sumps or tanks, the capacity of holding vessels, and the
relative turbulence that occurs during peak flows.
• Locate open wastewater conveyances or mixing structures.
• Find visible evidence of reactive or gas/vapor-toxic conditions, such as high temperatures or turbulence in
a tank, mist formation, or evidence of equipment corrosion. If necessary, use instrumentation (such as a
pH meter or redox meter)to check the corrosivity of solutions in open tanks, and the concentration of
vapors that might be released.
• Identify potential hazards to future inspectors.
• Visually confirm the reasonableness of flow estimates used in the water balance.
After the field evaluation, the inspector should have identified any incompatible internal wastestreams and
any wastewaters (including combined wastestreams) or exposure locations in the facility that may cause gas/vapor
toxicity problems. The facility hazard summary sheets should be updated accordingly.
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5.2 PHASE 2: PERFORM HAZARDS ANALYSIS
The hazards analysis phase has three parts: (1) evaluation of hazards resulting from chemical management
practices at the industry; (2) screening of industrial discharges for their potential to cause reactivity or gas/vapor
toxicity problems; and (3) selection of hazard mitigation options (See Figure 5-1). This chapter discusses the first
two parts; Chapter 6 discusses the third.
5.2.1 Evaluating Chemical Management Practices
During the plant tour, the POTW inspector should observe, and ask questions about, the chemical
management practices on site. At that time the inspector should either discuss changes in management practices
directly with company officials or develop enough background information to justify setting specific permit
requirements. After the plant tour the inspector should clarify new information (such as the hazards of
previously-unidentified substances) and organize that information to help identify mitigation options. The
following examples illustrate how the evaluation can be conducted:
EXAMPLE 1: A FUTURE HAZARD REQUIRING PREVENTATIVE ACTION
During the inspection of a paper mill, the inspector inquires about future changes in wastewater treatment
practices. The inspector learns that the mill's treatment plant operator is planning to treat the wastewater
from the bleach plant with ferric sulfate in order to flocculate solids. The inspector measures the pH of the
bleach plant wastewater and finds it near neutral, but the redox meter indicates a large positive (strongly
oxidizing) reading. The inspector identifies, and mill engineers confirm, that the mill's bleaching agent; are
chlorine, chlorine dioxide, calcium hypochlorite, and sodium hydroxide.
If the plant operator adds ferric sulfate to the wastewater as planned, acid will be released, the wastewater
pH will decrease, and chlorine and chlorine dioxide gas (which are corrosive and potentially explosive) will
evolve. This is an immediate hazard to the POTW inspector and plant personnel, and requires prompt action.
The inspector should immediately inform plant personnel of the potential problem and require immediate
action. The inspector might recommend an alternative approach such as wastewater dechlorination before
solids removal. Sulfur dioxide addition will treat both hypochlorite and chlorous/chloric ions (from chlorine
dioxide addition) in the wastewater.
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EXAMPLE 2: POTENTIAL RE ACTIVITY HAZARDS
A battery manufacturer notifies the POTW staff that it has installed a mercury-zinc specialty battery
production line and wishes to recover mercury from process line wastewater by sodium borohydride
addition. The manufacturer provides treatment plant specifications to the POTW for review.
Technical references note that sodium borohydride is a powerful reducing agent, which reacts with water
and water vapor to evolve hydrogen gas and sodium hydroxide. Hydrogen gas is a dangerous fire risk at the
industrial user and possibly in the collection system, and will require adequate ventilation at the industry's
treatment plant. The generation of sodium hydroxide (and hence a high pH) will require wastewater
neutralization prior to discharge to the POTW.
During the facility inspection, the inspector carefully reviews the manufacturer's batch treatment system.
Although plant engineers seem knowledgeable about the treatment process, and continuously operating
spark-proof exhaust fans have been installed in the treatment area, the treatment operator seems to have
minimal knowledge of potential hazards. The inspector notes that development of standard operating
procedures, including safety, by industry personnel should be evaluated as a BMP for the facility.
5.2.2 Screening Industrial Discharges
Chapter 4 described the two screening techniques the POTW can use when performing Phase 2 — hazards
analysis — of the problem identification process. This section presents an example of such a screening.
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EXAMPLE 3: DISCHARGE SCREENING
PART A: SCREENING FOR GAS/VAPOR TOXICITY
An organic chemical manufacturing industry produces carbon tetrachloride from carbon disulfide. When
POTW personnel inspect the facility, they notice a sulfide ("rotten egg") odor to the facility's discharge.
Suspecting the presence of volatile contaminants at high concentrations, the inspector—using personal
protective equipment—collects a zero headspace (VOA) sample of the discharge. The sample results are as
follows:
Carbon disulfide
Carbon tetrachloride
Chloroform
50mg/l
10 mg/1
1 mg/1
These levels vastly exceed the gas/vapor toxicity-based screening levels in Table 4-2, which are:
Carbon disulfide
Carbon tetrachloride
Chloroform
0.06 mg/1
0.03 mg/1
0.41 mg/1
The discharge may pose a gas/vapor toxicity hazard to industrial user personnel and the collection system
crew. To find the reduction needed, the screening procedure for mixtures in Appendix B is applied. The
calculated vapor phase concentrations (discharge concentration x Henry's Law Constant), ACGIH TLV-
TWA criteria, and concentration criteria ratios are as follows:
Pollutant
Carbon disulfide
Carbon tetrachloride
Chloroform
Equilibrium Vapor
Phase (mg/tn3)
24500
9560
120
TLV-TWA
(mp/m3)
31
31
49
Fraction of
TLV-TWA
790.32
308.39
2.45
1101.16
Assuming additive toxicity for all three compounds, the reduction required for all three compounds to
alleviate the potentially gas/vapor-toxic condition is: [1 - (1/1101.16)] X 100 = 99.9% reduction.
This reduction is so large that the industry may decide to uses pollution prevention measures to eliminate the
three compounds from the wastestream, rather than install new treatment technologies.
PART B: SCREENING FOR REACTIVITY
As previously discussed, the screening procedure can also be used to evaluate reactive hazards posed 'by a
wastewater discharge—such as the flammability of carbon disulfide in the example above. Carbon disulfide
is highly flammable; it has a flashpoint of -30' C (-22' F) and an LEL in air of 1.3 %. Table 4- 2 shows that
the screening level for carbon disulfide, based on flammability and explosivity, is 6.3 mg/1, which is well
below the 50 mg/1 current discharge level. The industry's discharge, then, may also pose a flammability
hazard. If the industry took remedial measures to reduce carbon disulfide by 99.9 %, the potential
flammability hazard would be alleviated. As was the case above, the percent reduction is so large that
significant pollution prevention measures are likely to be necessary.
This example illustrates how the POTW can use screening levels to identify potential gas/vapor toxicity and
flammability/explosivity hazards posed by an industry's discharge. If the POTW staff were to start a
program to identify all potential hazards, the basic screening methodology would remain the same but be
repeated for each potential hazard identified.
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5.3 SURVEYING THE POTW
The POTW can also use the approaches described above to identify potential reactivity and gas/vapor toxicity
problems in its collection system and treatment plant.
5.3.1 Collection System Concerns
Although most industrial users with potentially gas/vapor-toxic discharges should have been identified by the
screening processes described above, some may not have been identified because of changes in operating
practices, treatment system failure, or other problems. The POTW should identify, on a sewer map, which
industrial users have the highest potential to cause gas/vapor toxicity problems and the trunk lines and laterals
with the greatest number of these industries. POTW staff should sample wastewaters at these locations (using
appropriate protective equipment), and should use Appendix B to calculate combined gas/vapor-toxic effects for
these lines. If pump stations are located on these lines, the POTW should consider installing early-warning
devices such as organic vapor analyzer (OVA) meters and explosivity meters.
The POTW should be aware of new industrial facilities and facilities that are changing or adding process lines
when reviewing discharge characteristics and the potential for reactivity problems. The POTW should also
consider the potential for solids to have accumulated in the sewers or collection system from previous operations;
such solids could be reactive with constituents in the new discharge.
The POTW may also wish to review sewer maps and grades to identify spots where the construction of the
system or the surrounding topography may let vapors accumulate. Some POTWs may have already completed
this evaluation. For example, the POTW may have already completed the evaluation when seeking a waiver
from the sulfide standards required by the leather tanning categorical standards.
5.3.2 Treatment Plant Concerns
POTW staff should be aware of potential reactivity and gas/vapor toxicity problems within the treatment plant
itself, even if such problems are not associated with normal discharges. Toxic gases or vapors are likely to be of
greatest concern toward the beginning of the treatment train, such as at the headworks or in aerated tanks or grit
chambers, but reactivity or gas/vapor toxicity problems may exist throughout the plant—even at sludge drying
operations.
The use of chlorine at the POTW may pose a fire, explosion, or toxicity threat as well. Workers should
know emergency procedures for dealing with chlorine leaks at the plant, and, in case of an emergency, the local
fire department should know where chlorine storage tanks are located. As described in Section 5.2, the POTW
should characterize the results of the industrial facility survey according to the nature of the hazard (is it
immediate or potential?), the cause of the problem (is it the discharge itself or the configuration of the
enclosure?), and appropriate remedial actions.
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6. CONTROL OF POTENTIAL HAZARDS
Chapter 2 of this manual introduced the reader to working definitions of reactivity and gas/vapor toxicity, and
Chapters 3 and 4 discussed how to characterize their potential hazards to the POTW and its workers. Chapter 5
described how to identify and analyze the potential health and safety hazards of reactive or gas/vapor-toxic
industrial discharges. This chapter addresses how a POTW can regulate facilities that store or discharge reactive
and gas/vapor-toxic chemicals, and how it can protect its own workers from the discharges from such facilities.
6.1 CONTROLLING HAZARDS AT INDUSTRIAL USERS
Historically, POTWs have used controls that respond to, rather than anticipate or prevent, industrial
discharges of reactive or gas/vapor-toxic constituents. Such "after-the-fact" measures include narrative sewer
use ordinance provisions that require notification after a spill has occurred. As discussed in Chapter 1, in 1990
EPA issued regulations which were developed to prevent discharges of reactive or gas/vapor-toxic compounds
that may interfere with POTW operations, pass through the treatment works with inadequate treatment, or
jeopardize POTW worker health and safety. This section discusses the legal authorities that must be in place and
the specific provisions of industrial user permits (or other control mechanisms) that can be used to prevent or
control the discharge of reactive or volatile pollutants to the POTW and that require the industrial user to provide
a safe working environment for POTW employees on site. (Note: This section refers to permits, although
POTWs may use other individual control mechanisms. See 40 CFR 403.8(f)(l)(iii).)
6.1.1 Legal Authority
A POTW's legal authority to control the use of its sewers and treatment systems typically derives from its
local sewer use ordinance. The ordinance should describe the local pretreatment program in a manner that
provides both control and flexibility: it must clearly define the minimum responsibilities of all industrial users
while giving the POTW the flexibility to develop additional industry-specific controls as necessary. Additional
industry-specific controls are usually enforced through industrial user permits (or other control mechanisms), and
may be facility-specific where adverse health effects are apparent or suspected (see Section 6.1.2).
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To ensure it can control the discharge of reactive and gas/vapor-toxic constituents to its collection system, the
POTW should ascertain which authorities currently exist in its sewer use ordinance and seek authority to impose
additional constraints where necessary. Section 1.1 discussed how the new specific discharge prohibitions in
EPA's general pretreatment regulations [40 CFR 403.5(b)] control the discharge of reactive and gas/vapor-toxic
compounds. Each municipality must adopt, in its local ordinance, or other source of authority, measures at least
as stringent as the following prohibitions:
• No discharge to the POTW shall result in toxic gases or vapors within the POTW in a quantity that may
cause acute worker health and safety problems; and
• No discharge to the POTW shall contain pollutants which create a fire or explosion hazard in the POTW,
including, but not limited to, wastestreams with a closed-cup flashpoint less than 140* F (60* C).
In addition to adopting the new Federal prohibitions, the municipality should ensure that other provisions of
the ordinance allow it the discretion to impose and enforce specific controls on its industrial users where site
specific information exists. The following is an abbreviated list of the ordinance provisions which allow the
POTW to institute and enforce controls specifically addressing reactive pollutants:
• Permit application requirement — The POTW should have the authority to require the user to submit all
information necessary to characterize the quantity and quality of the user's discharge.
• Right to deny or condition anv discharge — The POTW must have the authority to deny or limit the
discharge from any nondomestic user that may, in any way, cause interference or pass through at the
POTW. The POTW must also have the authority to discontinue any discharge which appears to present
an imminent endangerment to the health or welfare of persons.
• Right of entry — The POTW must have access to the entire industrial facility, including all process and
storage areas. Entry should not be limited to only those processes that normally generate wastesiireams.
• Right to develop and enforce permit conditions — The POTW needs the authority to develop any
conditions it deems appropriate to ensure compliance with the ordinance and with State and Federal laws
and regulations.
EPA's Industrial User Permitting Manual (1989), and Guidance for Developing Control Authority Enforcement
Response Plans (1989) further discuss legal authority and sewer use ordinances.
6.1.2 Specific Industrial User Requirements
If a POTW has identified a specific industrial user as an actual or potential source of a discharge containing
reactive or gas/vapor-toxic constituents, it should place requirements in the user's control mechanism to
specifically address that discharge. The POTW should also impose specific permit conditions if an inspection
reveals unsafe practices or conditions at the user's facility. Chapter 5 described how to identify users with the
potential to create these hazardous discharges or conditions. This chapter describes how to write permit
conditions that will address such users and how to incorporate these conditions into industrial user permits or
6-2
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other control mechanisms. The POTW should consider three types of preventive permit conditions —
management practices, data collection/studies, and discharge limitations — as well as notification requirements in
the event of an accidental discharge or other permit violation.
6.1.2.1 Management Practices
Industrial user management plans are a practical way to control industrial discharges of reactive or
gas/vapor-toxic pollutants and to mitigate unsafe conditions at the industrial user's facility. Such plans,
incorporated into permit requirements, are an effective way to address existing or potential problems and help the
industrial user understand its responsibilities to control the release of reactive or gas/vapor-toxic volatile
pollutants. Slug control management plans [40 CFR 403.8(f)(2)(v)] and Total Toxic Organics (TTO) certification
[40 CFR 433.12(a)] are other management plans which may be in place at an industrial user.
There are at least two ways to incorporate industrial user management plans into permits: (1) by requiring
the user to develop and use a written set of procedures (on either a comprehensive basis or to address a specific
problem); or (2) by imposing site- or pollutant-specific requirements (such as the removal or sealing of floor
drains or containment of stored chemicals). The permit writer should be cautioned to use clear and enforceable
language to identify the specific activities which must occur and when these activities must be completed.
If the industrial user is required to develop a procedures manual, a POTW engineer should carefully evaluate
it when submitted to the POTW. However, it is not generally necessary or advisable for the POTW to approve
the plan required by the permit. Approval of the plan may be misconstrued as a POTW sanction, even though the
plaii, when implemented, may not be effective in controlling the hazard.
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Industrial user management plans may be grouped into two general categories: baseline and advanced. Both
baseline and advanced plans should include the following types of management practices:
• A material inventory system to identify all sources and quantities of toxic materials present at the
industrial facility;
• Employee training programs to help personnel of all levels understand the hazards at the facility and the
mitigative and safety procedures to be followed;
• Inspection and preventive maintenance procedures to routinely inspect plant equipment and operations for
potential hazards (such as possible equipment failure, or deterioration of pipes, valves, or tanks), arid to
correct such conditions;
• Inspections of chemical compatibility in storage areas, and the compatibility of containers with their
surroundings; and
• An incident reporting system to ensure that problems are reported to proper authorities and that records
are maintained regarding remediation measures taken and procedures that must be revised to prevent
recurrences of problems.
Baseline management practices typically are used when information on a particular industrial site is limited
but where potential problems have been identified. Baseline practices generally have the advantage of applying to
all industries with similar manufacturing processes or chemical handling practices (such as industries that store or
use significant amounts of organic solvents).
More advanced management plans are possible, and appropriate, when specific hazards need to be addressed:
• Prevention practices control the release of contaminants by covering, enclosing, or actually removing a
hazardous substance from a site. These include construction of physical barriers to contain vapors or
splashing, and the use of exhaust hoods to remove gases.
• Mitigation and detection practices are used when exposure to hazards is still possible despite prevention
practices. These include use of protective clothing and direct-reading equipment by POTW staff, and the
installation of hazard detectors by the industrial user.
• Response practices are adopted in case of accidental or otherwise uncontrolled releases. These include
the identification of industry officials with first-line response authority, the identification of possible
contaminant migration pathways, the stockpiling of sorbent/containment materials, and the placement of
response and safety equipment.
The POTW may choose to require one or all of the management practices discussed above. Management
practices should be individually tailored to each industrial user's own circumstances and should be incorporated
into the "Special Conditions" section of the user's permit. Additional information on management practices; to
prevent accidental or uncontrolled discharges can be found in the EPA Control of Slug Loadings to POTWs
Guidance Manual (1991).
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6.1.2.2 Data Collection/Studies
The POTW may include monitoring and reporting requirements in its industrial users' permit beyond the
routine compliance monitoring for discharge limits. Such special monitoring may be used to identify and set
limits for pollutants known to be present, and can be used to evaluate whether a pollutant-specific management
plan is necessary or whether facility-specific limits should be set based on the facility's ability to segregate or
treat the wastestream in question.
The POTW may also require the industrial user to undertake special data collection activities in cases where
problems such as worker health effects have been identified. In such a case the POTW might require special
monitoring of both the industry's wastestream and the sewer air space at the point of connection to the sewer line
to find any cause/effect relationship between the facility's discharge and the perceived health hazard. The
industrial user may be required through its permit to conduct this study and to submit a report describing the
conditions monitored and the actions to be taken to alleviate those conditions. In all cases, the permit writer must
ensure that these monitoring and reporting requirements are incorporated into the permit as enforceable
conditions. Likewise, where the industry proposes solutions to alleviate the hazardous situation, the POTW
should incorporate the recommendations into an enforceable compliance schedule with fixed milestone dates and
reporting requirements.
6.1.2.3 Facility Specific Discharge Limits
POTWs must apply the general and specific prohibitions to all industrial users [40 CFR 403.5(c)]. In order
to ensure compliance with the prohibitions, the POTWs may find it necessary to set facility specific effluent limits
for certain pollutants which have been identified as actual or potential hazards to the POTW or its employees.
If discharge monitoring data is available from a known event where an industrial discharge created a
gas/vapor-toxic hazard, the POTW permit writer should use this monitoring data when establishing a discharge
limit. If discharge monitoring data is not available, the permit writer may consider using the screening method
discussed in Section 4.1 as a starting point for setting discharge limits. The permit writer should be aware of the
limitations of the gas/vapor-toxicity screening method discussed in Section 4.1.2 and Appendix B. One of the
most significant limitations of the screening method is that it does not take into account possible synergistic
effects which could occur when the wastewater constituents combine. Section 4.2.3 of the Guidance Manual on
the Development and Implementation of Local Discharge Limitations Under the Pretreatment Program (December
1987) discusses estimating the effects of mixed discharges.
The reactivity prohibition [40 CFR 403.S(b)(l)] defined reactive pollutants to include wastestreams with a
closed-cup flashpoint less than 140' F or 60' C. Unlike the prohibition of gas/vapor-toxic pollutants, compliance
with the flashpoint condition can be directly measured in the industrial user's wastestream. Direct measurement
is the easiest method for determining compliance with flashpoint condition of this mandatory prohibition. The
approved test methods are specified in 40 CFR 261.21.
6-5
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6.1.3 OSHA E
The POTW may also consider using OSHA's Permissible Exposure Limits (PELs), to impose controls on
gas/vapor toxicity. OSHA PELs were originally promulgated in 1971 based on 1968 ACGIH TLVs and other
Federal and industry standards, and they continue to be revised and strengthened. OSHA has published PELs (at
29 CFR 1910.1000 - 1910.1101) for about 600 substances, including benzene, vinyl chloride, lead, acrylonitrile,
asbestos, dibromochloropropane, and inorganic arsenic. OSHA standards also exist for 13 carcinogens for which
zero inhalation exposure is allowed.
Since OSHA is a regulatory agency, its PELs are legally enforceable by OSHA or OSHA-approved State
programs and apply to most private industries and all Federal agencies. Depending on State law, the PELs may
also apply to State and local employees. Table 6-1 lists the 23 States and 2 Territories with OSHA-approved
occupational safety and health programs. To determine whether PELs apply to its workers, the POTW should
contact the appropriate State office listed in Appendix G.
OSHA PELs are based on both health effects and the economic and technical feasibility of achieving the
exposure limits. Other exposure limits, such as the NIOSH Recommended Exposure Limits (RELs) and the
ACGIH TLVs discussed in Chapter 4, are based solely on preventing adverse health effects. Therefore the more
conservative exposure limit should be used as the controlling exposure limit whenever possible. Exposure limits
can be used to develop industrial discharge screening levels using the procedures discussed in Chapter 4 and
Appendix B.
TABLE 6-1. STATES AND TERRITORIES WITH OSHA-APPROVED
WORKER HEALTH AND SAFETY PROGRAMS
Alaska
Arizona
California
Connecticut
Hawaii
Indiana
Iowa
Kentucky
Maryland
Michigan
Minnesota
Nevada
New Mexico
New York
North Carolina
Oregon
Puerto Rico
South Carolina
Tennessee
Utah
Vermont
Virgin Islands
Virginia
Washington
Wyoming
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6.2 CONTROLLING HAZARDS AT THE POTW
Regardless of which controls are used to prevent reactive or gas/vapor-toxic discharges from its industrial
users, the threat of an accidental spill into the sewer system cannot be overlooked. For this reason, the POTW's
inspectors, maintenance personnel, and treatment plant operators should be aware of potential hazards and have
protective equipment available to mitigate these hazards. The POTW also should develop a comprehensive health
and safety program that identifies dangerous tasks and situations, provides training for field and POTW crews that
might be exposed to these situations, and ensures that POTW staff have detection devices and protective
equipment to safeguard them when hazardous situations occur. EPA's Office of Emergency and Remedial
Response has published Standard Operating Safety Guides which provide detailed information on reducing
employee exposure to chemical hazards. The EPA Control of Slug Loadings to POTWs Guidance Manual (1991)
discusses management practices and other procedures to prevent, control, and respond to accidental and otherwise
uncontrolled discharges to POTWs.
Reactive or gas/vapor-toxic chemicals may be present throughout the POTW — not only at the treatment
plant, but also at pumping stations and points within the collection system. To prevent worker exposure to such
chemicals, the POTW should develop a comprehensive worker health and safety program that identifies
potentially hazardous conditions and sets strict protocols for workers under these conditions. The Water
Environment Federation's Manual of Practice on Safety and Health in Wastewater Systems (1983) recommends
that a written program consist of:
• Statement of policy, including major program objectives;
• List of work practice standards, rules, and regulations;
• List of assignments of responsibilities;
• Policy for enforcement of safety rules and disciplinary action;
• Means for detecting and correcting violations;
• Procedures for reporting and investigating accidents;
• Procedures for an emergency response system;
• Procedures for using new chemicals; and
• Procedures for documenting plant actions.
Each of the program elements above should include provisions to protect workers from gas/vapor toxicity and
reactive chemicals.
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6.2.1 Data Collection and Hazard Identification
The health and safety program should contain a hazard identification process that identifies potentially
hazardous tasks and situations to which POTW workers could be exposed during daily work activities. Using the
data collection and evaluation activities suggested in Section 5.1 of this manual, the hazard identification process
should include every stage of wastewater generation, conveyance, and treatment—including the following:
• Detailed inspections of industrial facilities, including production and storage areas;
• Inspection and monitoring of industrial pretreatment processes;
• Inspection and monitoring within the industry's wastewater collection system;
• Inspection and monitoring within the POTW's collection system;
• Operation and maintenance of pump stations; and
• Operation and maintenance activities at the POTW treatment plant.
After identifying potential hazards, the POTW should outline them in a job safety analysis report which
should be made available to ail POTW employees working in the areas listed above. The job safety analysis
outline should clearly which precautions and special equipment might be necessary when undertaking these tasks.
6.2.2 Worker Training
After identifying safe work procedures for POTW employees who might be exposed to reactive or
gas/vapor-toxic industrial discharges, it is essential to train employees in these procedures. Central to any
successful health and safety program is a clear mandate from the POTW administration that safety is a primary
objective, that unsafe practices and conditions will not be tolerated, and that no employee should engage in any
tasks without proper training to address the potential hazards of that task. This policy must be made clear to all
POTW workers. The POTW should take follow-up actions, including disciplinary action, where violations of the
policy occur.
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An effective employee training program combines classroom discussions, on-the-job training, and practical
exercises in emergency procedures. All employees, regardless of their work activities, should be trained in the
following:
• The POTW's mandated health and safety policy;
• Basic requirements of the health and safety program;
• The employees' responsibility to report all unsafe working conditions to supervisors;
• Hazard identification;
• Accident reporting responsibilities;
• The operation and testing of safety equipment; and
• Emergency response procedures.
The POTW should provide additional, more specific, training to each worker who might be exposed to toxic
gases and vapors, or reactive chemicals during inspection and monitoring duties. Each worker should be required
to review the job safety analysis report for the industry to be visited, and be trained in use of detection equipment
or protective gear that may be needed to perform the required tasks. Each employee who may be exposed to
hazardous work conditions related to reactivity or gas/vapor toxicity should be trained in the following areas:
• Comprehensive knowledge of the POTW's health and safety program;
• Job safety analysis reports for each task or situation that might be encountered during normal duties;
• Use of vapor monitoring equipment, where applicable; and
• Use of protective clothing and equipment, where applicable.
6.2.3 Hazard Detection Equipment
POTW workers who inspect and monitor facilities where they may be exposed to toxic gases or vapors,
should be outfitted with personal equipment designed to detect potential health hazards (which is readily available
from safety and mining equipment manufacturers). This equipment should be able to detect all three types of
hazardous atmospheres — oxygen-deficient, combustible, and toxic. Ideally, such equipment would be capable of
monitoring the atmosphere before a worker enters a potentially hazardous area (such as a chemical storage areas)
as well as continuous monitoring while workers are in the work area. Of less general use, but still valuable to a
health and safety program, are instruments designed to detect specific hazards, including oxygen meters,
combustible gas detectors, hydrogen sulfide detectors, chlorine detectors, and sulfur dioxide detectors.
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The POTW also may wish to use permanent gas detection equipment, installed at critical points within the
collection system and the treatment plant, to provide early warning of potential problems and alert field personnel
of potential hazards in or near these areas. Chapter 3 describes the capabilities and limitations of these
instruments in more detail.
6.2.4 Personal Protective Equipment
Whenever source control, engineering controls, and safe work practices are either infeasible or insufficient to
ensure worker protection, personal protective equipment (PPE) should be used to reduce exposure. PPE consists
of respirators and protective clothing, and should be used with the air monitoring devices described in section
6.2.3.
POTW staff should be trained in the use of PPE, including the following:
• Capabilities and limitations of particular • Cleaning, inspecting, maintaining, and repairing
PPE ensembles; PPE; and
• The consequences of not following • Human factors affecting PPE performance.
instructions for checking, fitting, and using
PPE;
6.2.4.1 Respirators
A respirator consists of a faceplate connected to either an air purifying device or a source of supplied air.
The relative advantages of air-purifying and supplied-air respirators are outlined in Appendix H.
Air-purifying respirators are used in atmospheres containing known concentrations of specific chemicals.
Canisters and cartridges in such respirators attach to the faceplate and remove specific airborne contaminants
(particulates, organic vapors, acids, bases, gases, or fumes) by filtration, absorption, adsorption, or chemi<;al
reaction. Air purifying respirators may not be used in atmospheres with:
• Oxygen deficiencies;
• Immediately dangerous to life and health (IDLH) concentrations; or
• Contaminants having inadequate odor warning properties.
A supplied-air respirator (self-contained breathing apparatus, or SCBA) must be used if the above conditions
exist. Generally, supplied-air respirators are more appropriate for POTW workers because of the large number
of pollutants present and the limited availability of monitoring equipment that can identify specific contaminants.
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The selection of a respirator depends on the hazards expected at the site and the nature and duration of the
tasks to be performed. At a minimum, each POTW employee working in an area where toxic gases or vapors
could occur should be equipped with an escape SCBA unit. All employees expected to use respirators should be
fit-tested and trained in use and maintenance, with annual refresher training.
6.2.4.2 Protective Clothing
Protective clothing shields skin from injury caused by direct contact with chemical splashes or vapors. The
extent of such protection varies according to the type of material used, since no material protects against all
chemicals or combinations of chemicals. If possible, the POTW should choose the protective clothing ensemble
that offers the highest protection possible against chemical hazards anticipated at the POTW or other areas where
POTW workers might encounter hazards. When direct contact with known chemicals is anticipated, the clothing
manufacturer should be contacted about the protective properties. Note that with all types of materials tears or
penetration along seam lines, zippers, or imperfections may occur.
Appendix I lists the effectiveness of various protective materials against chemical degradation. For more
information on the protectiveness of clothing types, the POTW should contact the manufacturer or consult
ACGIH's 1985 Guidelines for the Selection of Chemical Protective Clothing (Second Edition). Other factors to
consider when selecting protective material are:
• Durability; • Compatibility with other equipment; and
• Flexibility; • Duration of use.
• Temperature effects;
Appendix J describes various types of protective clothing, including head, foot, hand, eye, face, and ear
protection. At a minimum, a POTW worker engaged in normal work activities (that is, without exposure to toxic
gases, fumes, or vapors) requires the following:
• Tyvek or cotton overalls; • Steel-toed shoes; and
• Polyurethane or latex gloves; • Safety helmet.
• Safety glasses or goggles;
Protective clothing ensembles should be tailored to hazards known to exist at the POTW and should be
reevaluated whenever hazardous conditions change.
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APPENDIX A
LOWER EXPLOSIVE LIMITS
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APPENDIX A
LOWER EXPLOSIVE LIMITS
Explosive Compound
Lower
Explosive Limit
(96 by volume)
Explosive Compound
Lower
Explosive Limit
(% by volume)
Paraffin hydrocarbons
Methane
Ethane
Propane
Butane
Isobutane
Pentane
Isopentane
2,2-Dimethylpropane
Hexane
Heptane
2,3-Dimethylpentane
Octane
Nonane
Decane
Olefins
Ethylene
Propylene
Butene-1
Butene-2
Amylene
Aromatics
Benzene
Ethylbenzene
Cumene
Toluene
Xylene (o.m.p)
Cyclic Hydrocarbons
Cyclopropane
Cyclohexane
Methylcyclohexane
5.0
3.0
2.1
1.8
1.8
1.4
1.4
1.4
1.2
1.0
1.1
0.95
0.85
0.75
2.7
2.4
1.6
1.7
1.4
1.3
1.0
0.9
1.2
1.1
2.4
1.3
1.1
Alcohols
Methyl alcohol 6.7
Ethyl alcohol 3.3
Allyl alcohol 2.5
n-Propyl alcohol 2.2
Isopropyl alcohol 2.2
n-Butyl alcohol 1.7
n-Amyl alcohol 1.4
Isoamyl alcohol 1.4
Aldehydes
Acetaldehyde 4.0
Crotonaldehyde 2.1
Paraldehyde 1.3
Propionaldehyde 2.9
Ethers
Methyl ethyl ether 2.2
Diethyl ether 1.9
Divinyl ether 1.7
Tetrahydrofuran 2.0
Ketones
Acetone 2.6
Acetophenone 1.1
Methyl ethyl ketone 1.9
Methyl propyl ketone 1.6
Methyl butyl ketone 1.2
Acids
Acetic acid 5.4
Adipic acid 1.6
Hydrogen cyanide 5.6
Hydrogen sulfide 4.0
Esters
Methyl formate 5.0
Ethyl formate 2.8
Methyl acetate 3.2
Source: Adapted from "Hazards Evaluation and Risk Control Services Data Guide Bulletin HE-109A," Hercules
Corp., 1982
A-l
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Explosive Compound
Lower
Explosive Limit
(96 by volume)
Explosive Compound
Lower
Explosive Limit
(% by volume)
Esters (Continued)
Ethyl acetate
Propyl acetate
Isopropyl acetate
Butyl acetate
Amyl acetate
Hydrogen
Hydrogen
Nitrogen Compounds
Ammonia
Aniline
Cyanogen
Pyridine
Ethyl nitrate
Ethyl nitrite
Oxides
Carbon monoxide
Ethylene oxide
Propylene oxide
Dioxan
Sulfides
Carbon disulfide
Dimethyl sulfide
Hydrogen sulfide
Ethyl mercaptan
2.2
1.8
1.7
1.4
1.0
4.0
15.0
1.2
6.6
1.8
4.0
3.0
12.5
3.6
2.8
2.0
1.3
2.2
4.0
2.8
Chlorides
Methyl chloride 7.0
Ethyl chloride 3.8
Propyl chloride 2.4
Butyl chloride 1.8
Allyl chloride 2.9
Amyl chloride 1.6
Vinyl chloride 3.6
Propylene dichloride 3.1
Chlorobenzene 1.4
Bromides
Methyl bromide 10.0
Allyl bromide 2.7
Amines
Methyl amine 4.7.
Ethyl amine 3.5
Dimethyl amine 2.8
Propyl amine 2.0
Diethyl amine 1.8
Trimethyl amine 2.0
Triethyl amine 1.2
Fuels
Gasoline 1.2
Jet fuel JP-4 1.3
Hydrazine 4.7
Solvents
Butyl cellosolve 1.1
Methyl cellosolve 2.5
Methyl cellosolve acetate 1.7
N,N-Dimethyl formamide 1.8
Turpentine 0.''
Source: Adapted from "Hazards Evaluation and Risk Control Services Data Guide Bulletin HE-109A," Hercules
Corp., 1982
A-2
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APPENDIX B
SCREENING TECHNIQUE TO IDENTIFY GAS/VAPOR TOXIC DISCHARGES
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APPENDIX B
SCREENING TECHNIQUE TO IDENTIFY GAS/VAPOR TOXIC DISCHARGES
To identify industrial user (IU) discharges which could potentially generate gas/vapor toxic conditions in
sewer atmospheres, an IU discharge screening procedure should be established. This screening procedure
would identify gas/vapor toxic pollutant discharges warranting control through the imposition of local limits
and/or other IU requirements.
The screening technique discussed in this appendix entails: (1) identifying gas/vapor toxicity criteria; (2)
conversion of gas/vapor toxicity criteria into corresponding IU discharge screening levels; and (3) comparison
of these screening levels with actual IU discharge levels. Discharges above the specified screening level may
warrant further investigation by the POTW.
The American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value-time
weighted averages (TLV-TWAs) serve as a reference for gas/vapor toxicity from which IU discharge screening
levels can be calculated. The ACGIH TLV-TWA gas/vapor toxicity levels are the vapor phase concentrations
of volatile organic compounds to which nearly all workers may be repeatedly exposed, over an 8-hour workday
and a 40-hour work week, without adverse effect. In general, POTW workers are not exposed for an extended
period of time to sewer atmospheres contaminated with volatile compounds, so the use of TLV-TWA
concentrations as a basis for developing IU discharge screening levels can be considered a conservative practice.
The calculation of screening levels that are based on gas/vapor toxicity involves the following four steps:
1. Identify the ACGIH TLV-TWA concentration of the pollutant of concern. ACGIH TLV-TWA
concentrations (rng/m3) for several representative organic pollutants are presented in the second column
of Table B-l.
2. Identify the Henry's Law Constant for the pollutant of concern. Table B-2 presents the Henry's Law
Constants for several volatile organics.
B-l
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3. Convert the Henry's Law Constant to the appropriate units. In order to calculate screening levels based
on ACGIH TLV-TWA concentrations, the Henry's Law Constant must be expressed in terms of
(mg/mVCmg/l). The following equation should be used to convert the Henry's Law Constant expressed
in units of atm nrVmol to the equivalent constant expressed in (mg/m3)/(mg/l):
He = HA x 1 x 10"
where: HC = Henry's Law Constant, (mg/m3)/(mg/l)
HA = Henry's Law Constant, (atm mVmol)
R = Ideal gas constant, 0.08206 (atm 1/mol K)
T = Temperature corresponding to vapor pressure* used to derive HA
(See Table B-2), K
Henry's Law Constants expressed in (mg/m3)/(mg/l) are presented for several volatile organics in the
third column of Table B-l.
4. Calculate the IU discharge screening level from the Henry's Law expression:
CLVL = CVA?
H
where
CLVL = Discharge screening level, mg/1
CVAP = ACGIH TLV-TWA, mg/m3
H = Henry's Law Constant, (mg/m3)/(mg/l)
Screening levels derived by this equation should be compared with actual IU discharge levels measured at
the IU's sewer connection. This method for deriving screening levels assumes instantaneous
volatilization of pollutant to the sewer atmosphere (i.e., instantaneous attainment of equilibrium) and does
not take into account dilution of IU wastewater within the collection system. Screening levels should be
used to identify gas/vapor toxic pollutants for control.
Screening levels calculated from ACGIH TLV-TWA data address only the toxicities of individual
compounds. The screening levels presented in Table B-l do not address the generation of toxic concentrations
of gases that are produced from the mixture of chemicals in the wastestream. The following procedure allows
the POTW to predict the potential vapor toxicity associated with the discharge of a mixture of volatile organic
compounds:
1. Analyze the industrial user's wastewater discharge for volatile organics. The following are hypoihetical
monitoring data:
Discharge
Pollutant Level, mg/1
Benzene 0. 1
Toluene 0.9
Chlorobenzene 2.2
B-2
-------
Pollutant
1,2-Dichlorobenzene
1,4-Dichlorobenzene
Discharge
Level. my/L
3.57
3.39
Although these discharge levels are all below the corresponding screening levels presented in Table B-l,
the POTW should determine whether the simultaneous discharge of the five pollutants could result in a
gas/vapor toxic mixture within the sewer.
2. Use Henry's Law,
CVAFOR = H x CDBCHARce
where
CVAPOR = Vapor phase concentration, mg/m3
H = Henry's Law Constant, (mg/m')/(mg/l)
CDISCHARGE = Discharge level, mg/1,
to calculate the equilibrium vapor phase concentration of each pollutant:
Pollutant
Benzene
Toluene
Chlorobenzene
1,2-Dichlorobenzene
1,4-Dichlorobenzene
Discharge
Level, mg/1
0.1
0.9
2.2
3.57
3.39
Henry's Law Constant
(mg/m3V(mg/n
225
277
149
80.2
127
Equilibrium
Vapor Phase
Concentration, mg/m3
22.5
249.3
327.8
286.3
430.5
3. Express the equilibrium vapor phase concentrations (above) as fractions of the corresponding
TLV-TWA's:
Pollutant
Benzene
Toluene
Chlorobenzene
1,2-Dichlorobenzene
1,4-Dichlorobenzene
Equilibrium
Vapor Phase
Concentration, mg/m3
22.5
249.3
327.8
286.3
430.5
TLV-TWA
g/m3
32
377
345
301
451
Fraction of
TLV-TWA
0.70
0.66
0.95
0.95
0.96
4.22
*Assume T = 298.15K if data not available.
B-3
-------
4. Sum the fractions of the TLV-TWAs. In the example above, the sum of the TLV-TWA fractions
equals 4.22.
If the compounds in question are assumed to possess additive gas/vapor toxicities when mixod, then
if the sum of the TLV-TWA fractions is greater than 1.00, a potentially gas/vapor toxic condition
exists.
5. If the sum of the TLV-TWA fractions is greater than 1.00, calculate the percentage by which the
concentrations of the compounds need to be reduced in order to avoid a potentially gas/vapor toxic
condition. Using the example values:
1 - 1 x 100 = 76% reduction of the discharge of all five pollutants to alleviate the
4.22 potentially gas/vapor toxic condition (assuming additive toxicities and
the applicability of the Henry's Law Constants).
B-4
-------
TABLE B-l. DISCHARGE SCREENING LEVELS
Compound
Acrylonitrile
Aldrin
Benzene
Bis(2-chloromethyl)ether
Bromoform
Bromomethane
Carbon disulfide
Carbon tetrachloride
Chlordane
Chlorobenzene
Chloroethane
Chloroform
Chloromethane
1 ,2-Dichlorobenzene
1 ,4-Dichlorobenzene
Dichlorodifluoromethane
1 , 1 -Dichloroethane
trans- 1 ,2-Dichloroethylene
1 ,2-Dichloropropane
1 ,3-Dichloropropene
Dieldrin
Diethyl phthalate
4,6-Dinitro-o-cresol
Dinitrotoluene
Endrin
Ethyl benzene
Ethylene dichloride
Formaldehyde
Heptachlor
Hexachloro-1 ,3-butadiene
Hexachloroethane
Hexachlorocyclopentadiene
ACGffi TLV-TWA
mg/m3
4.3
0.25
32.0
0.0044
5.2
20.0
31.0
31.0
0.5
345
2600
49.0
103
301
451
4950
810
793
347
4.5
0.25
5.0
0.2
1.5
0.1
434.0
40.0
1.2
0.5
0.21
9.7
0.11
BASED UPON
Henry's Law
Constant*
(mg/m3)/(mg/l)
3.62
0.65
225
8.58
22.0
8189
490
956
0.39
149
6152
120
15796
80.2
127
121801
177
2785
96.0
55.3
0.02
0.05
0.06
0.21
0.02
274
38.0
20.8
163
1064
104
0.0008
GAS/VAPOR TOXICITY
Screening Level
mg/1
1.19
0.38
0.14
0.0005
0.24
0.002
0.06
0.03
1.27
2.31
0.42
0.41
0.07
3.75
3.55
0.04
4.58
0.28
3.62
0.08
13.0
107
10.78
7.21
4.9
1.59
1.05
0.06
0.003
0.0002
0.093
658
B-5
-------
TABLE B-l. DISCHARGE SCREENING LEVELS
Compound
Methyl chloride
Methyl ethyl ketone
Methylene chloride
Naphthalene
Nitrobenzene
Pentachlorophenol
Phenol
ACGIH TLV-TWA
mg/m1
103
590.0
174.0
52.0
5.0
0.5
19.0
1 , 1 ,2,2-Tetrachloroethane 6.9
Tetrachloroethylene
Toluene
Toxaphene
1 ,2,4-Trichlorobenzene
1,1, 1-Trichloroethane
1 , 1 ,2-Trichloroethane
Trichloroethylene
Trichlorofluoromethane
Vinyl chloride
Vinylidene chloride
Aroclor 1242
Aroclor 1254
""Henry's Law Constant
339.0
377.0
0.5
37.0
1910.0
55.0
269.0
5620.0
13.0
20.0
1.0
0.5
BASED UPON GAS/VAPOR
Henry's Law
Constant*
(mg/m')/(mg/l)
1798
2.37
84.4
19.62
0.53
0.11
0.02
15.5
636
277
200
94.0
1226
48
378
4573
4251
7766
80.9
106
TOXICITY
Screening Level
mg/1
0.06
249
2.06
2.65
9.41
4.37
1024
0.44
0.53
1.36
0.003
0.39
1.55
1.15
0.71
1.23
0.0003
0.003
0.01
0.005
(mg/m3)/(mg/l) taken from Table B-2.
B-6
-------
TABLE B-2. HENRY'S LAW CONSTANTS EXPRESSED IN ALTERNATE UNITS
Compound
Acenaphthylene
Acrylonitrile
Aldrin
Anthracene
Benzene
Bis(2-Chlorotnethyl)Ether
Bromoform
Bromomethane
Carbon disulfide
Carbon tetrachloride
Chlordane
Chlorobenzene
Chloroethane
Chloroform
Chloromethane
1 ,2-Dichlorobenzene
1 , 3 -Dichlorobenzene
1 ,4-Dichlorobenzene
Dichlorodifluoromethane
1 , 1 -Dichloroe thane
1 ,2-Dichloroethylene
trans- 1 ,2-Dichloroethylene
1 ,2-Dichloropropane
1 ,3-Dichloropropene
Dieldrin
Diethyl Phthalate
4,6-Dinitro-o-Cresol
Dinitrotoluene
Endrin
Ethyl benzene
Ethylene dichloride
*A temperature of 25 °C was
Henry's Law Constant*
(atm m')/mol
1.45 X 10"3
8.80 x 10-5
1.60 x lO"5
1.25 x ia3
5.50 x lO"3
2.1 x 104
5.32 x 1O4
1.97 x 10-'
1.20x ia2
2.30 x 10-2
9.63 x lO*
3.58 x 10°
1.48 x 10"'
2.88 x ID"3
3.80 x 10-'
1.93 x ia3
3.61 x ia3
3.10x 10"3
2.98 x 10°
4.26 x ia3
l.lOx ia3
6.70 x ia2
2.31 x 10-3
1.33 x lO'3
4.58 x ia7
1.14x 10-*
1.4x 10-6
5.09 x 10-*
5.00 x ia7
6.60 x ia3
9.14x 104
assumed in Henry
(mol/m'HiBft/1)
3.96 x 1O4
6.83 x ia5
1.79x 10*
2.87 x 1O4
2.88 x 10°
7.46 x lO"5
8.41 x ia5
8.62 x 10-2
6.44 x ia3*
6.21 x 10"3
9.61 x ia7
1.32 x ia3
9.54 x ia2
1.00 x 10-3
3.13x 10-'*
5.46 x 10-4
i.oox ia3
8.62 x 1O4
1.01 x 10°
1.79 x lO"3
4.64 x 10-4
2.87 x 10-2
8.50 x 104
4.98 x 104
4.91 x 10-*
2.10x ia7
2.89 x 10-7
1.14x ia«
5.37 x 10-"
2.58 x ia3
3.84 x 10-4
's Law calculations.
(mg/m'KmgA)
60.3
3.62
0.65
51.1
225
8.58
22
8189
490*
956
0.39
149
6152
120
15796
80.2
148
127
121801
177
44.96
2785
96.0
55.3
0.02
0.05
0.06
0.21
0.02
274
38.0
Temperature (°C)
Vapor
Pressure S
20
22.8
~
25
25
—
-
20
-
20
~
20
20
20
20
20
25
25
25
20
-
20
20
20
—
-
—
—
-
20
20
ohibffity
25
25
-
25
25
-
-
20
-
20
-
25
20
20
20
20
25
25
25
20
-
20
20
25
-
-
-
-
-
20
20
B-7
-------
TABLE B-2. HENRY'S LAW CONSTANTS EXPRESSED IN ALTERNATE UNITS
Com pound
Formaldehyde
Heptachlor
Hexachloro-l,3-butadiene
Hexachlorocyclopentadiene
Hexachloroethane
Methyl Chloride
Methyl ethyl ketone
Methylene chloride
Naphthalene
Nitrobenzene
Pentachloroe thane
Phenol
1 , 1 ,2,2-Tetrachloroethane
Tetrachloroethylene
Toluene
1 ,2,4-Trichlorobenzene
1,1,1 -Trichloroethane
1,1, 2-Trichloroethane
Trichloroethylene
Trichlorofluoromethane
Vinyl chloride
Vinylidene chloride
*A temperature of 25 °C was
Henry's Law Constant*
(atm m')/mol
5.1 x 1O4
4.00 x 10-3
2.56 x ia2
1.6 x ia2
2.49 x ia3
4.4 x ia2
5.80 x 10-5
2.03 x ID"3
4.80 x ID"4
1.30 x 10-5
2.17x ia3
4.54 x ID"7
3.80 x 10"4
1.53 x lO"2
6.66 x ia3
2.30 x ia3
3.00 x lO"2
1.17x 10°
9.10x 10°
l.lOx 10-'
1.04 x ID"1
1.90 x 10-'
assumed in Henry
(mol/m'Xmg/l)
6.94 x 10-*
4.38 x 10-4
4.08 x 10-3
2.40 x 10°
4.37 x 10-4
3.56 x 10-2
3.29 x ia5*
9.93 x 104
1.53 x 1O4
4.32 x 10-*
4.38 x 10-4*
1.97 x 10-7
9.25 x 10"s
3.83 x 10-3
3.01 x ia3
5.18x 10-4
9.19x 10-3
3.60 x 10-4
2.88 x 10-3
3.33 x 10-2
6.80 x 10-2
8.01 x 10-2
's Law calculations.
(mg/m'Xmg/l)
20.8
163
1064
0.0008
104
1798
2.37*
84.4
19.62
0.53
88.7*
0.02
15.5
636
277
94.0
1226
48
378
4573
4251
7766
Temperature ("O
Vap°r Solubility
Pressure
-
25
20
-
20
-
-
20
~
-
—
-
-
20
20
25
25
-
20
20
25
25
..
25
20
._
22
...
...
25
•~
-
-
-
-
20
:i5
:i5
25
-
20
20
25
20
B-8
-------
TABLE B-2. HENRY'S LAW CONSTANTS EXPRESSED IN ALTERNATE UNITS
Compound
Aroclor 1242
Aroclor 1248
Aroclor 1254
Aroclor 1260
Henry's Law Constant*
(aim m*)/mol (mol/m')(mg/I) (mg/m»)(mg/l)
1.98 xlO-3** 3.14x10-**** 80.9
3.60 x 10-3** 5.04 x 10-4*** 147
2.60 x 10"3** 3.26 x 104*** 106
7.40 x 10-'** 8.38 x 10"2*** 30246
Tpnneratare (*C. 1
^r. — »
25 25
25 25
25 25
25 25
**Source: U.S. EPA "Aquatic Fate Process Data for Organic Priority Pollutants." EPA 440/4-81-014
***The molecular weights of the following compounds were used to represent the molecular weights of
Aroclor mixtures in Henry's Law calculations:
Aroclor 1242
Aroclor 1248
Aroclor 1254
Aroclor 1260
Trichlorobiphenyl
Tetrachlorobiphenyl
Pentachlorobiphenyl
Hexachlorobiphenyl
B-9
-------
APPENDIX C
SCREENING TECHNIQUE TO IDENTIFY
FLAMMABLE/EXPLOSIVE DISCHARGES
-------
APPENDIX C
SCREENING TECHNIQUE TO IDENTIFY FLAMMABLE/EXPLOSIVE DISCHARGES
This appendix describes a screening procedure that will help identify flammable/explosive pollutant
discharges warranting control through the imposition of local limits and/or other IU requirements.
A variety of screening procedures to identify flammable/explosive pollutant discharges have been developed.
This section describes one approach, which entails:
1. Conversion of lower explosive limit (LEL) data into corresponding IU discharge screening levels, and
2. Comparison of these screening levels with actual IU discharge levels. Discharges that exceed screening
levels may warrant further investigation by the POTW (e.g., monitoring and sampling to determine
source).
The calculation of LEL-based screening levels is a five-step process:
1. Determine the LEL of the pollutant of concern. LELs are typically expressed as percent
(volume/volume)-in-air concentrations. LELs for several volatile organics are presented in the second
column of Table C-l.
2. Convert 10% of the compound's LEL concentration to a vapor phase concentration (CVAP) expressed in
mol/m3 (third column of Table C-l):
CVA, = (0.10XLEL) P x 10
where
CVAP =LEL expressed as a vapor phase concentration, mol/m3
LEL = Lower explosive limit, percent (volume/volume)
P = Total pressure, 1 atmosphere (atm) (assumed)
R = Ideal gas constant, 0.08206 atm L/mol K
T = Temperature, 298.15 K (assumed).
3. Determine the Henry's Law Constant for the pollutant of concern. Since the screening level is to be
expressed as a concentration in water and the LEL is a vapor phase concentration, a partitioning constant
is needed to convert LEL values to corresponding water phase discharge levels. The Henry's Law
Constant serves this function for pollutants present in low concentration, as are normally encountered in
IU discharges. Table C-2 presents Henry's Law Constants (in various units) for several organics.
4. Convert the Henry's Law Constant to the appropriate units. The Henry's Law Constants presented in
Table B-2 are expressed in terms of three different units:
• (atmm3)/mol
• (mol/m3)/(mg/l)
C-l
-------
In the literature, Henry's Law Constants are most commonly expressed in terms of pressure | (atm
m3)/(mol)]. To derive LEL-based screening levels, however, the Henry's Law Constant must be
expressed in terms of (mol/m3)(mg/l). The following equation should be used to convert the Henry's
Law Constant expressed in units of (atm m')/(mol) to the equivalent constant expressed in
(mol/m3)/(mg/l):
HB= HAx 1 x 103
(MW)(R)(T)
where: HB = Henry's Law Constant, (mol/m3)/(mg/l)
HA = Henry's Law Constant, (atm m3)/mol)
MW = Molecular weight, g/mol
R = Ideal gas constant, 0.08206 (atm I/mol K)
T = Temperature corresponding to vapor pressure* used to derive HA (see
Table C-l), K
Henry's Law Constants expressed as (mol/m3)(mg/L) are presented for several volatile organics in the
fourth column of Table C-l.
5. Calculate the IU discharge screening level using the Henry's Law expression (fifth column of
Table C-l):
CLVL = —CVAP
H
where
CLVL = Discharge screening level, mg/1
CVAP = LEL expressed as a vapor phase concentration, mol/m3
H = Henry's Law Constant (mol/m3)/(mg/l)
Screening levels derived by this equation should be compared with actual IU discharge levels
measured at the lU's sewer connection. This method for deriving screening levels assumes
instantaneous volatilization of the pollutant to the sewer atmosphere (i.e., instantaneous attainment of
equilibrium) and does not take into account dilution of IU wastewater within the collection system.
Table C-l presents LEL-based screening levels, calculated using the method described above, for several
organics. The screening levels should be used to identify flammable/explosive pollutants for control.
*Assume T = 298.15 K if data not available.
C-2
-------
TABLE C-l. DISCHARGE SCREENING LEVELS BASED ON EXPLOSIVITY
Compound
Acrylonitrile
Benzene
Bromoethane
Carbon disulfide
Chlorobenzene
Chloroethane
Chloromethane
1,2-DichJorobenzene
1,3-Dichlorobenzene
1,4-Dichl orobenzene
1, 1-Dichloroethane
1,2-Dichoroethylene
trans- 1, 2-Dichloroethylene
1,2-Dichloropropane
1 ,3-Dichloropropene
Ethyl benzene
Ethylene dichloride
Formaldehyde
Methylene chloride
Methyl ethyl ketone
Naphthalene
Nitrobenzene
Phenol
Toluene
1,2,4-Trichlorobenzene
1,1,1-Trichloroethane
Trichloroethylene
Vinyl chloride
Vinylidene chloride
LEL%
3.0
1.4
10.0
1.0
1.3
3.8
8.1
2.2
2.2
2.2
5.6
9.7
9.7
3.4
5.3
1.0
6.2
7.0
12.0
2.0
0.9
1.8
1.7
1.27
2.5
7.5
8.0
3.6
6.5
(^(mol/m3)*
0.123
0.057
0.409
0.041
0.053
0.155
0.331
0.090
0.090
0.090
0.229
0.396
0.397
0.139
0.217
0.041
0.253
0.286
0.490
0.082
0.037
0.074
0.069
0.052
0.102
0.307
0.327
0.147
0.266
H(mol/m3 )/(mg/L)**
6.84 x 10'5
2.88 x 10'3
8.62 x lO'2
6.44 x 10 3
1.32 x 10'3
4.54 x 10-2
3.13 x 10'1
5.46 x 10-4
1.00 x 10-3
8.62 x 10'4
1.79 x 10°
4.64 x 10-3
2.87 x 10-2
8.50 x 10"4
4.98 x lO^1
2.58 x lO'3
3.84 x 10-"
6.94 x 10"4
9.93 x 10-4
3.29 x 10'5
1.53 x 104
4.32 x 10"*
1.97 x lO'7
3.01 x lO'3
5.18 x 10-4
9.19 x 10'3
2.88 x lO'3
6.80 x 10'2
8.01 x 10-2
^LVL(mg/L)***
1794
20
4.7
6.3
40
1.6
1.1
165
90
104
128
85
14
164
435
16
660
412
494
2486
240
17046
350253
17
197
33
114
2.2
33
* Vapor phase concentration calculated from LEL, assuming temperature = 25 °C.
* 'Henry's Law Constants (mol/m3)/(mg/l) taken from Table B-2
"""'Screening level based on 10 percent of the LEL.
C-3
-------
APPENDIX D
SAMPLE HEADSPACE MONITORING ANALYTICAL PROCEDURE
(CINCINNATI APPROACH)
-------
APPENDIX D
SAMPLE HEADSPACE MONITORING ANALYTICAL PROCEDURE
(CINCINNATI APPROACH)
CMSD ANALYTICAL METHOD
VAPOR SPACE ORGANICS
January 28, 1984
July 11, 1986
REVISED September 27, 1990
Page 1 of 5
ANALYTICAL PROCEDURE
A vapor standard is prepared by injecting 1.6 ^1 (microliter) of hexane into a one (1) liter flask or bottle
fitted with a septum stopper. The hexane is vaporized by heating the flask to 100°C for eight (8) minutes. The
Flask is allowed to cool to room temperature. A one thousand (1000) /xl aliquot of the vapor is removed with a
gas-tight syringe. The vapor is injected into the gas chromatograph (GC). The area under the curve is
integrated electronically.
The GC is equipped with a packed column and a flame ionization detector. (If a capillary column is used,
the sensitivity will increase and the run time will decrease). Good separation will be achieved by using a 2 mm
ID glass or stainless steel column 8 feet long, packed with 1 % SP-1000 on Carbopak-B 60/80 mesh. The GC
oven temperature is programmed as follows: SO°C for 3 minutes, 8°C/minute to 220°C for 18 minutes.
I. SAMPLING PROCEDURE
All samples will be grab samples.
A. Sample Vial Preparation
Use 40 ml vials (as described in 44 FR 69468, 12/3/79; Pierce No. 13075) equipped with open top
screw cap and Teflon-coated silicon septum (Pierce No. 12722). Vials must be washed with
detergent, rinsed with tap water followed by distilled water and then dried at 105°C for one (1)
hour. Ten (10) mg Na2S2O3 should be added to vials if the sample is suspected of containing an
oxidant.
B. Sampling
1. A clean vial is immersed in the wastewater and is filled until the liquid forms a convex surface
with respect to the top of the bottle. The bottle is capped and then inverted to check for an air
bubble. If a bubble is present, repeat the process until no bubbles are present when the bottle is
inverted after being filled and capped. Store the sample at 4°C (ice) and transport to the
laboratory.
D-l
-------
CMSD ANALYTICAL METHOD
VAPOR SPACE ORGANICS
January 28, 1984
July 11, 1986
REVISED September 21, 1990
Page 2 of 5
2. If it is not possible to fill the 40 ml vial directly from the wastestream, the following
procedure may be employed: Using a 1 liter glass jar that has been washed as in section IA, fill
the jar with the wastewater. Transfer a portion of the water to the 40 ml vial and proceed as
described above. This method is useful when the wastestream is not readily accessible for
sampling. For example, the 1 liter jar may be attached to a pole and the sample obtained by
immersing the bottle below the surface of the wastestream.
C. Storage
The samples will be stored in a refrigerator at 4°C, all samples will be analyzed in less than 14 days
from the time of collection. Vials will be stored inverted.
H. SUPPLIES AND EQUIPMENT
A. Equipment
1. Gas Chromatograph: Hewlett Packard Model S880 with Flame lonization Detector and level
for integrator, or equivalent.
2. Microsyringe: Hewlett Packard 10 juL (PN 9301-0246) or equivalent.
3. Injector Septum: Hewlett Packard Blue (PN 5180-4184), or equivalent. (One for each six (6)
injections.)
4. One liter Amber Boston Round (Fisher #03-320-IE) Modified to accept a septum, or
equivalent.
5. Gas Tight Syringe: one (1) ml (Supleco #2-0739M), or equivalent.
6. Column: 8 ft. x 2 mm. ID stainless steel 1% SP-1000 on Carbopack B (Supleco #1-2548), or
equivalent.
7. Sample vials: Clear glass 40 ml with hole in top cap and Teflon faced septum (supelco #2-
3285M), or equivalent.
8. Assorted tubing, regulators, and purifying equipment for gas lines.
B. Supplies
1. Hexane GC/MS Grade (Fisher #H303-4)
2. Ultrapure Helium
3. Ultrapure Air
4. Ultrapure Hydrogen
D-2
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CMSD ANALYTICAL METHOD
VAPOR SPACE ORGANICS
January 28, 1984
July 11, 1986
REVISED September 27, 1990
Page 3 of 5
III. INSTRUMENT SETTINGS
A. Temperature Profile: 50°C for 3 minutes, 8°C/minute to 220°C, 220°C for 18 minutes. Stop run.
B. Detector Temperature: 250°C
C. Injector Temperature: 220°C
D. Carrier: Helium, with the flow set to give hexane's main peak a retention time of 18-20 minutes
(about 30 ml/minute).
IV. ANALYSIS
A 40 ml vial containing the sample is removed from the refrigerator and warmed to room temperature.
Using a glass syringe (20 ml or larger) remove 20 ml of liquid by piercing the septum. It will be
necessary to replace the liquid withdrawn with a gas. Nitrogen is preferred, to avoid contamination.
The 20 ml of liquid removed can be discarded or injected into another 40 ml vial and used as a duplicate
sample. It will be necessary to vent air from the second vial as it is filled.
The vial is equilibrated at 21 _+ 3°C for a of minimum 1 hour, vigorously shaken 30 times and held
quiescent at 21 _+ 3°C for 10 minutes before analysis. Using a gas-tight syringe, withdraw a one
thousand (1000) /iL aliquot of the headspace gas and inject into the GC. The column and temperature
programming should be as specific for the hexane standard. The carrier gas is helium at a flow rate that
gives hexane a retention time of approximately 18-20 minutes (about 30 ml/minute).
The total peak area of the chromatogram will be used to calculate the ppm hexane to which the area is
equivalent. The peak area of compounds eluting in less than 2 minutes will be considered as methane.
The ppm equivalent to methane will be subtracted from the total ppm of hexane to yield the ppm of
vapor space organics (VSOs). Samples with a VSO value equivalent to or greater than 300 ppm may be
screened by GC/MS to identify whether major peaks represent substances classified as priority pollutants
by the EPA.
V. QUALITY CONTROL
A. A field blank will be run daily and will be considered as a zero standard.
B. A 30 ppm standard will be run daily. The total peak area must be 9.0 to 11.0 percent of the 300
ppm standard.
C. A 300 ppm standard will be run daily.
D. Other standards may be run as necessary.
E. A same vial duplicate will be run for each 10 samples. The duplicate must have a margin of error
less than 20 percent based on total hexane peak area.
D-3
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CMSD ANALYTICAL METHOD
VAPOR SPACE OF.GANICS
January 28, 1984
July 11, 1986
REVISED September 27, 1990
Page 4 of 5
VI. CALCULATIONS
The vapor concentration of the hexane standard is calculated as follows:
PPm - V - 24.47 X
298
w = weight of hexane (density x volume (ml))
MW= molecular weight of hexane
v = gram molecule volume of mixture in liters
P = ambient pressure in mm
t = ambient temperature, °C
V = volume of flask or bottle in liters
The concentration of total organics in the head space is calculated as follows:
ppm = (ppm hexane standard) (total peak area of sample)
(total peak area of hexane standard)
The value is reported as hexane.
The concentration of the "methane" in the head space is calculated as follows:
ppm = (pom hexane standard) (total peak area of compounds with a retention time of less than 2.0 minutest
(total peak area of the hexane standard)
The concentration of VSOs in the head space is as follows:
ppm = (ppm total organics) - (ppm "methane")
D-4
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CMSD ANALYTICAL METHOD
VAPOR SPACE ORGANICS
January 28, 1984
July 11, 1986
REVISED September 27, 1990
Page 5 of 5
CMSD technicians have found the following step-by-step sequence effective in preparing and running the hexane
standard:
1. Record the date, lab temperature and barometric pressure. If using a new standard bottle,
determine its volume by filling it with water, then measure the water volume in a graduated
cylinder.
2. Purge the standard with house air for 30 seconds.
3. Rinse the standard about 6 times with hexane.
4. With the microsyringe needle in the hexane, pump the plunger several times to expel air from
the needle. Then draw the plunger above the 2.5 n\ mark.
5. Withdraw the microsyringe from the hexane, hold the syringe with the needle up, and tap to
expel any air bubbles.
6. Gradually lower the plunger to the 1.5 to 1.6 jtl mark. Pull the plunger back until all the
hexane contents of the microsyringe are visible. There should be 2.7 to 2.8 /tl of hexane in
the microsyringe.
7. Inject the hexane into the standard bottle, being careful not to lose the septum.
8. After withdrawing the microsyringe from the septum, pull the plunger back to determine the
amount of hexane left in the microsyringe. This should be about 1.1 jxl.
9. Subtract the remaining amount of hexane in the microsyringe from the amount in step 6.
This should yield approximately 1.5 - 1.7 /tl of hexane. Record the value.
10. Heat the bottle in an 80°C oven for 30 minutes or an 103 °C oven for 8 to 9 minutes. Cool
thoroughly (about 30 minutes) before injecting standards.
11. Run a 30 and a 300 ppm standard each day. For the 30 ppm standard, a 100 pi aliquot of
the vapor is removed from the standard bottle with a gas-tight syringe. The vapor is injected
into the GC, being sure not to loosen the syringe needle. This procedure is repeated using a
1000 fil aliquot for the ppm standard.
D-5
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APPENDIX E
VOLATILE ORGANIC PRIORITY POLLUTANTS
-------
APPENDIX E
VOLATILE ORGANIC PRIORITY POLLUTANTS
1. Acrolein - used as feedstock for some types of plastics, plasticizers, acrylates, textile finishes and synthetic
fibers.
2. Acrvlonitrile - used in the manufacture of acrylic fibers, acrylostyrene plastics, nitrile rubbers, surface
coatings and adhesives.
3. Benzene - used in the manufacture of detergents, dyes, linoleum, artificial leather, varnishes, lacquers,
explosives, Pharmaceuticals, and pesticides. Also used as a motor fuel constituent, as a solvent, and in the
extraction of oils from seeds and nuts.
4. Bromoform - used in pharmaceutical and fire-resistant chemical manufacturing, and as a solvent.
5. Carbon tetrachloride - used as a solvent, and to chemically synthesize fluorocarbons; also used as dry
cleaning agent, a fire extinguishing agent, and a fumigant.
6. Chlorobenzene - used as a solvent for degreasing and in paint and pesticide manufacturing.
7. Chlorodibromomethane (dibromochloromethane) - no uses.
8. Chloroethane - used in the manufacture of tetraethyl lead, dyes, drugs, and ethyl cellulose, as a solvent and
a refrigerant. Has very low water solubility.
9. 2-chloroethvl vinvl ether - used in the manufacture of anesthetics, sedatives, and cellulose ethers.
10. Chloroform - widely used as a solvent, especially in the lacquer industry, is also used as a cleaning agent,
and in the manufacture of pharmaceuticals, plastics, dyes, pesticides, floor polishes and fluorocarbons.
11. Dichlorobromomethane - used as a laboratory reagent.
12. 1.2-dichloroethane - converted to vinyl chloride and other chlorinated chemicals. Is also used as a solvent,
degreaser, and a dry cleaning agent and in the manufacture of nylon, rayon, rubber, paint, varnish, and
finish removers.
13. 1.1 -Dichloroethane - is used as a solvent and cleaning agent in specialized processes.
14. 1.1 -Dichloroethvlene - used as an intermediate for the copolymerization with other monomers to produce
"vinylidene polymer plastics."
15. 1.2-Dichloropropane - used as a degreaser and a dry cleaning agent and in the manufacture of plastics,
rubber, and waxes.
16. 1.3-Dichloropropvlene - used together with 1,2-dichloropropene as a soil fumigant.
17. Ethvlbenzene - intermediate in the synthesis of styrene, and in the manufacture of cellulose acetate and
synthetic rubber. Is used as a solvent for paints, varnishes, coatings, and enamels.
18. Methvl bromide - used as insect fumigant, a refrigerant, an herbicide, a fire extinguishing agent, for
degreasing wool and extracting oils from nuts, flowers, and seeds.
19. Methvl chloride - used as an extractant in petroleum refineries, a solvent in the synthetic rubber industry,
as a paint remover, or in solvent degreasing.
20. Methvlene chloride - widely used as a solvent by many industries and for extraction in the food industry.
E-l
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21. 1.1.2.2-Tetrachloroethane - used as a nonflammable solvent and as a dry cleaning agent and in the
manufacture of chlorinated hydrocarbons, paint, varnish, lacquers, cement and rust removers.
22. Tetrachloroethvlene - widely used solvent particularly as a dry cleaning agent and for metal degreasLng.
23. Toluene - major raw material for organic chemical synthesis, is also used in paints, organic dyes, coatings,
and inks and as a solvent.
24. Trans-1.2-Dichloroethvlene - is used as a solvent in the extraction of rubber, as a refrigerant, and in
pharmaceutical manufacturing.
25. 1.1.1-Trichloroethane - major use is as a metal cleaning solvent and degreaser.
26. 1.1.2-Trichloroethane - used as a solvent and as an intermediate in organic synthesis.
27. Trichloroethvlene - used as metals degreasing agent and as an organic solvent; is in a wide variety of
solvent cleaning products.
28. Vinyl Chloride - used primarily as a vinyl monomer in the manufacture of polyvinyl chloride plastic resin.
E-2
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APPENDIX F
INFORMATION COLLECTION/DECISION SHEET
-------
INSTRUCTIONS FOR THE INFORMATION COLLECTION/DECISION SHEET
PURPOSE:
The purpose of the information collection/decision sheet is to provide a convenient and organized structure
for evaluating POTW information needs, and for determining the type, quantity and quality of additional data
needed (if any) to support the POTW decision making process. The process includes (1) defining the purpose
of the data collection, (2) evaluating the available data sources, and the adequacy of the data to support decision
making, and (3) designing data collection efforts to address any identified information gaps.
INSTRUCTIONS:
1. STATE THE PURPOSE OF THE INFORMATION COLLECTION: Provide a concise statement on
why the data are being collected, and how the data will ultimately be used. This second part of the question is
important since it will dictate the quantity and quality of the data to be collected.
2. CHECK THE EVALUATIONS THAT MUST BE UNDERTAKEN: To achieve the purpose of the
information collection, the chemical management practices may need to be characterized and evaluated. Six
check-off areas () are provided for this evaluation.
() Chemical inventory: This is applicable if the POTW wants more information about the types of materials
being stored (and used) at a facility. For example, the POTW might need to review chemical inventories to
verify that hazardous chemicals were no longer in use or to support efforts to characterize releases from process
areas.
a. Indicate the types of data needed: Provide the specific focus of information collection efforts.
b. List potential sources of the needed data: List potential sources of information, indicating those
already reviewed.
c. List specific needs related to the use of data: Be as specific as possible about the exact nature of the
data needed. For example, the data may need to have been collected within the last 2 months, or the
data may need to be obtained during a POTW inspection (as opposed to industry-supplied information).
() Determination of chemical characteristics at the process line: Since inspectors will be walking between
and breathing the air around chemical reaction tanks in the process areas, it is possible that health and safety
concerns would require characterization of the open areas of the process train.
a. Indicate the type of data needed: The information needed will vary depending on the particular
pollutant of concern. For example, the POTW may want to request information about the corrosive
nature of solutions and vapors or the chemical composition of solutions in process tanks.
b. List potential sources of data: As addressed above, list potential sources of information. This should
include all sources that might reasonably be surveyed; e.g., documentation from plant personnel,
information from chemical manufacturers. To allow for proper evaluation of the data, list references
that might be used to evaluate hazards.
c. List specific needs related to the use of data: Qualify the data needs and indicate any data
concerns. For example, if verbal information obtained during past conversations with industrial user
representatives has not been reliable, it is appropriate to indicate that written information is required.
F-l
-------
() Identification of chemical release points: Identify the locations where releases to the environment might
occur. These release points will be the points of highest chemical concentration and possibly the focus of
mitigation measures.
a. Indicate the type of data needed: Indicate whether formal drawings are needed, whether narrative
descriptions are appropriate, and any other relevant details. Also indicate whether characterization or
measurement of the actual releases is required.
b. List potential sources of data: List potential sources of information, indicating any that have already
been reviewed.
c. List specific needs related to the use of data: This might include readings (using a specific type of
instrument) and methodologies for collecting representative samples/measurements.
() Evaluation of the controls/mitigation measures: The POTW may be interested in evaluating the
performance of existing or planned engineering controls to determine whether they are adequate to address
hazards. Also the POTW may wish to review mitigative measures used to minimize the effect of releases after
the fact.
a. Indicate the type of data needed: Include information on the design and actual
performance of engineering controls, or information regarding equipment effectiveness for specific target
chemicals. Evaluating the effectiveness of mitigation measures might include review of the monitoring
data, and the effectiveness and types of mitigation employed.
b. List potential sources of data: Examples include manufacturer information, data from pilot-testing,
and industry monitoring data.
c. List specific needs related to the use of data: For example, information regarding control
equipment performance may need to be related to the particular contaminant matrix.
() Other: This section may be used as a catch-all for any other safety issues not addressed above.
F-2
-------
APPENDIX F
INFORMATION COLLECTION/DECISION SHEET
1. STATE THE PURPOSE OF THE INFORMATION COLLECTION (e.g. response to worker health and
safety concerns)
2. CHECK THE EVALUATIONS THAT MUST BE UNDERTAKEN
[ ] Chemical Inventory
a. Indicate the type of data needed:
b. What are the potential sources of data:
c. List specific needs relating to use of the data:
[ ] Determination of Chemical Concentrations at Process Line
a. Indicate the type of data needed:
b. What are the potential sources of data:
c. List specific needs relating to use of the data:
[ ] Identification of Chemical Release Points
a. Indicate the type of data needed:
b. What are the potential sources of data:
c. List specific needs relating to use of the data:
F-3
-------
[ ] Evaluation of Controls/Mitigative Measures
a. Indicate the type of data needed:
b. What are the potential sources of data:
c. List specific needs relating to use of the data:
[ ] Other, explain:
a. Indicate the type of data needed:
b. What are the potential sources of data:
c. List specific needs relating to use of the data:
[ ] Identification of Appropriate Safety Protocols for Future Inspections or Collection System Work
3. IDENTIFY ADDITIONAL DATA
4. WILL THE COLLECTED DATA SUPPORT ALL EVALUATIONS
[ ] Yes, stop here and perform necessary evaluations.
[ ] No - Proceed to 5.
F-4
-------
5. IDENTIFY SPECIFIC DATA NEEDS TO BE MET BY FACILITY INSPECTION (e.g. verification of
existing information)
Additional Comments:
Completed by: Date:
F-5
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APPENDIX G
STATES WITH APPROVED OSHA PLANS
-------
APPENDIX G
STATES WITH APPROVED OSHA PLANS
(AUGUST 1991)
NANCY BEAR, COMMISSIONER
Alaska Department of Labor
P.O. Box 21149
Juneau, ALASKA 99801
(907) 465-2700
LARRY ETCHECHURY, DIRECTOR
Industrial Commission of Arizona
800 W. Washington
Phoenix, ARIZONA 85007
(602) 255-5795
LLOYD W. AUBAY, DIRECTOR
California Department of Industrial Relations
395 Oyster Point Boulevard, 3rd Floor, Wing C
San Francisco, CALIFORNIA 94102
(415) 737-2960
RONALD F. PETRONELLA, COMMISSIONER
Connecticut Department of Labor
200 Folly Brook Boulevard
Wethersfield, CONNECTICUT 06109
(302) 566-5123
MARIO R. RAMIL, DIRECTOR
Hawaii Department of Labor and
Industrial Relations
830 Punchbowl Street
Honolulu, HAWAII 96813
(808) 548-3150
KENNETH J. ZELLER, COMMISSIONER
Indiana Department of Labor
1013 State Office Building
100 North Senate Avenue
Indianapolis, INDIANA 46204-2287
(317) 232-2665
ALLEN J. MEIER, COMMISSIONER
Iowa Division of Labor Services
1000 E. Grand Avenue
Des Moines, IOWA 50319
(515) 281-3447
CHARLES E. McCOY, ACTING
COMMISSIONER FOR WORKPLACE
STANDARDS
Kentucky Labor Cabinet
1049 U.S. Highway 127 South
Frankfort, KENTUCKY 40601
(502) 564-3070
HENRY KOELLEIN, JR., COMMISSIONER
Maryland Division of Labor and Industry
Department of Licensing and Regulation
501 St. Paul Place, 2nd Floor
Baltimore, MARYLAND 21202-2272
(301) 333-4179
LOWELL PERRY, DIRECTOR
Michigan Department of Labor
Victor Office Center
201 N. Washington Square
P.O. Box 30015
Lansing, MICHIGAN 48933
(517) 373-9600
VERNICE DAVIS-ANTHONY, DIRECTOR
Michigan Department of Public Health
3423 North Logan Street
Box 30195
Lansing, MICHIGAN 48909
(517) 335-8022
JOHN LENNIS, COMMISSIONER
Minnesota Department of Labor and Industry
443 Lafayette Road
St. Paul, MINNESOTA 55155
(612) 296-2342
LARRY McCRACKEN, ADMINISTRATOR
Nevada Department of Industrial Relations
Division of Occupational Safety and Health
Capitol Complex
1370 S. Curry Street
Carson City, NEVADA 89710
(702) 687-3032
JUDITH M. ESPINOSA, SECRETARY
New Mexico Environment Department
Occupational Health and Safety Bureau
1190 St. Francis Drive
P.O. Box 26110
Santa Fe, NEW MEXICO 87502
(505) 827-2850
THOMAS F. HARTNETT, COMMISSIONER
New York Department of Labor
State Office Building - Campus 12
Room 457
Albany, NEW YORK 12240
(518) 457-2741
G-l
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JOHN C. BROOKS, COMMISSIONER
North Carolina Department of Labor
4 West Edenton Street
Raleigh, NORTH CAROLINA 27601
(919) 733-7166
JOHN A. POMPEI, ADMINISTRATOR
Oregon Occupational Safety and Health Division
Oregon Department of Insurance and Finance
Labor and Industries Building, Room 160
Salem, OREGON 97310
(503) 378-3304
RUY N. DELGADA ZAYAS, SECRETARY
Puerto Rico Department of Labor and
Human Resources
Prudencio Rivera Martinez Building
505 Munoz Rivera Avenue
Hato Rey, PUERTO RICO 00918
(809)754-2119-22
VIRGIL W. DUFFIE, JR., COMMISSIONER
South Carolina Department of Labor
3600 Forest Drive
P.O. Box 11329
Columbia, SOUTH CAROLINA 29211-1329
(803) 734-9594
JAMES R. WHITE, COMMISSIONER
Tennessee Department of Labor
ATTN: Robert Taylor
501 Union Building
Suite "A" - Second Floor
Nashville, TENNESSEE 37243-0655
(615) 741-2582
DOUGLAS J. McVEY, ADMINISTRATOR
Utah Occupational Safety and Health
160 East 300 South
P.O. Box 5800
Salt Lake City, UTAH 84110-5800
(801) 530-6900
DANA J. COID-LEVISQUE, COMMISSIONER
Vermont Department of Labor and Industry
120 State Street
Montpelier, VERMONT 05620
(802) 828-2765
LUIS S. LIANOS, COMMISSIONER
Virgin Islands Department of Labor
2131 Hospital Street
Christiansted
St. Croix, VIRGIN ISLANDS 00840-4666
(809) 773-1994
CAROL AMATO, COMMISSIONER
Virginia Department of Labor and Industry
Powers Taylor Building
13 South 13th Street
Richmond, VIRGINIA 23219
(804) 786-2376
JOSEPH A. DHAR, DIRECTOR
Washington Department of Labor and Industries
Genera] Administration Building
Room 334 - AX-31
Olympia, WASHINGTON 98504-0631
(206) 753-6307
MIKE SULLIVAN, DIRECTOR
Department of Employment
Division of Employment Affairs
Occupational Safety and Health Administration
Herschler Building Second Floor East
122 West 25th Street
Cheyenne, WYOMING 82002
(307) 777-7786 OR 777-7787
G-2
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APPENDIX H
TYPES OF RESPIRATORS
-------
APPENDIX H
TYPES OF RESPIRATORS
Type of Respirator
Advantages
Disadvantages
Atmosphere Supplying
Self-Contained Breathing
Apparatus
(SCBA)
Provides the highest available
level of protection against
airborne contaminants and oxygen
deficiency.
Provides the highest protection
available under strenuous work
conditions.
Bulky, heavy [up to 35 pounds
(12.9 kg)].
Finite air supply limits work
duration.
May impair movement in confined
spaces.
Positive-Pressure
Supplied-Air Respirator
(SAR) (also called
air-line respirator)
Enables longer work periods than
SCBA.
Less bulky and heavy than a
SCBA. SAR equipment weighs
less than 5 pounds [or around IS
pounds (5.6 kg) if escape SCBA
protection is included].
Protects against most airborne
contaminants.
Not approved for use in
atmospheres immediately dangerous
to life or health (IDLH) or in
oxygen-deficient atmospheres unless
equipped with an emergency egress
unit such as an escape only SCBA
that can provide immediate
emergency respiratory
protection in case of air-line failure.
Impairs mobility.
MSHA/NIOSH certification
limits have length to 300 feet
(90 meters).
As the length of the hose is
increased, the minimum approved
air flow may not be delivered at the
facepiece.
Worker must retrace steps to leave
work area.
Requires supervision/
monitoring of the air supply line.
H-l
-------
Type of Respirator
Escape-only SCBA
Advantages
Lightweight [10 pounds (4.5 kg)
or less], low bulk, easy to carry.
Available in pressure-demand and
continuous-flow modes.
Supplies clean air to the wearer
from either an air cylinder or
from an oxygen-generating
chemical. Approved for escape
purposes only.
Enhanced mobility.
Disadvantages
Provides only 5 to 15 minutes of
respiratory protection, depending on
the model and wearer breathing
rate.
Cannot be used for entry.
Cannot be used in IDHL or oxygen-
deficient atmosphere (less than 19.5
percent oxygen at sea level).
Air Purifying
Air-Purifying
Respirator
(including powered
air-purifying respirators
[PAPRs])
Lighter in weight than SCBA.
Generally weighs 2 pounds (91kg)
or less (except for PAPRs)
High relative humidity may reduce
protection.
Limited duration of protection.
May be hard to gauge safe operating
time in field conditions.
Only protects against specific
chemicals and up to specific
concentrations.
Cannot be used when unknown
contaminants are present.
Must never be used for confined
space entry where exposure
conditions have not been
characterized.
Use requires monitoring of
contaminant and oxygen levels.
Can only be used (1) against gas
and vapor contaminants with
adequate warning properties, or (2)
for specific gases or vapors
provided that the service is known
and a safety factor is applied or if
the unit has an ESLI (end-of-
service-life indicator).
Adapted from Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities.
NIOSH, OSHA, USCG, aad EPA, October 1985.
H-2
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APPENDIX I
EFFECTIVENESS OF PROTECTIVE MATERIALS AGAINST
CHEMICAL DEGRADATION
-------
APPENDIX I
EFFECTIVENESS OF PROTECTIVE MATERIALS AGAINST
CHEMICAL DEGRADATION (BY GENERIC CLASS)
Generic Class
Alcohol
Aldehydes
Amines
Esters
Ethers
Fuels
Halogenated
Hydrocarbons
Hydrocarbons
Inorganic Acids
Inorganic Bases
Ketones
Organic Acids
Ratings are subject
by fabric.
E = EXCELL
Source: Adapted fi
Office of Research
Examples
Methyl alcohol
Ethyl alcohol
Acetaldehyde
Propionaldehyde
Methylamine
Propylamine
Methyl formate
Methyl acetate
Ethyl ether
Phenol ether
Gasoline
Jet fuel (JP-4)
Bromobenzene
Chlorobenzene
Hexane
Ethane
Hydrochloric acid
Ammonia
Ethylamine
Acetone
Methyl ethyl
ketone
Carbonic acid
Carboxylic acid
Butyl
Rubber
E
E-G
E-G
G-F
G-F
F-P
G-P
F-P
G-F
E
E
E
Polyvinyl
Chloride
E
G-F
G-F
P
G
G-P
G-P
F
E
E
P
E
Neoprene
E
E-G
E-G
G
E-G
E-G
G-F
G-F
E-G
E
G-F
E
Natural
Rubber
E
E-F
G-F
F-P
G-F
F-P
F-P
F-P
F-P
E
E-F
E
to variation depending on formulation, thickness, and whether the material is supported
ENT G = GOOD F = FAIR P = POOR
•om Survey of Personal Protective Clothing and Respiratory Apparatus. DOT. USCG.
and Development (September 1974).
1-1
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APPENDIX J
PROTECTIVE CLOTHING
-------
APPENDIX J
PROTECTIVE CLOTHING
Body Part Protected
Type of Clothing or Accessory
Description
Type of Protection
Use Considerations
Full Body
Fully-encapsulating suit
Non-encapsulating suit
Aprons, leggings, and sleeve
protectors
One-piece garment. Boots and
gloves may be integral,
attached and replaceable, or
separate.
Protects against splashes, dust,
gases, and vapors.
Jacket, hood, pants, or bib
overalls, and one-piece
coveralls.
Protects against splashes, dust,
and other materials but not
against gases and vapors.
Does not protect parts of head
or neck.
Fully sleeved and gloved
apron.
Separate coverings for arms
and legs.
Commonly worn over non-
encapsulating suit.
Provides additional splash
protection of chest, forearms,
and legs.
Does not allow body heat to
escape. May contribute to heat
stress in wearer, particularly if
worn in conjunction with a closed-
circuit SCBA; a cooling garment
may be needed. Impairs worker
mobility, vision, and
communication.
Do not use where gas-tight or
pervasive splashing protection is
required.
May contribute to heat stress in
wearer.
Needs tape-seal connections
between pant cuffs and boots and
between gloves and sleeves.
Whenever possible, should be used
over a non-encapsulating suit
(instead of using a fully-
encapsulating suit) to minimize
potential for heat stress.
Useful for sampling, labeling, and
analysis operations. Should be
used only when there is a low
probability of total body contact
with contaminants.
M
Adapted from Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities. October 1985. NIOSH/OSHA/USCG/EPA.
-------
Body Part Protected
Type of Clothing or Accessory
Description
Type of Protection
Use Considerations
Head
Safety helmet (hard hat)
Helmet liner
Hood
Protective hair covering
For example, a hard plastic or
rubber helmet.
Commonly worn with a
helmet.
Protects the head from blows.
Insulates against cold. Does
not protect against chemical
splashes.
Protects against chemical
splashes, participates, and rain.
Protects against chemical
contamination of hair.
Helmet shall meet OSHA standard
29CFRPart 1910.125
Particularly important for workers
with long hair.
Eyes and Face
Face shield
Splash hood
Goggles
Full-face coverage, eight-inch
minimum.
Sweat bands
Protects against chemical
splashes. Does not protect
adequately against projectiles.
Protects against chemical
splashes. Does not protect
adequately against projectiles.
Depending on their
construction, goggles can
protect against vaporized
chemicals, splashes, large
particles, and projectiles (if
constructed with impact-
resistant lenses).
Prevents sweat-included eye
irritation and vision
impairment.
Face shields and splash hoods
must be suitably supported to
prevent them from shifting and
exposing portions of the face or
obscuring vision. Provides limited
eye protection.
Ears
Ear plugs and muffs
Headphones
Radio headset with throat
microphone.
Protects against physiological
damage and psychological
disturbance.
Provides some hearing
protection while enabling
communication.
Must comply with OSHA
regulation 29 CFR Part 1910.95.
Can interfere with communication.
Highly desirable, particularly if
emergency conditions arise.
J-2
Adapted from Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities. October 1985. NIOSH/OSHA/USCG/EPA.
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Body Part Protected
Type of Clothing or Accessory
Description
Type of Protection
Use Considerations
Hands and Anns
Gloves and sleeves
May be integral, attached, or
separate from other protective
clothing.
Overgloves disposable gloves.
Protect hands and arms from
chemical contact. Provides
supplemental protection to the
wearer.
Wear jacket cuffs over glove cuffs
to prevent liquid from entering the
glove. Tape-seal gloves to sleeves
to provide additional protection.
Should be used whenever
possible to reduce
decontamination needs.
Feet
Safety boots
Disposable shoe or boot
covers
Boots constructed of chemical-
resistant material.
Boots constructed with some
steel materials (e.g., toes,
shanks, insoles).
Boots constructed from
nonconductive, spark-resistant
materials or coatings.
Made of a variety of materials.
Slip over the shoe or boot.
Protect feet from contact with
chemicals.
Protect feet from compression,
rushing, or puncture by falling,
moving, or sharp objects.
Protect the wearer against
electrical hazards and prevent
ignition of combustible gases
or vapors.
Protect safety boots from
contamination.
Protect feet from contact with
chemicals.
All boots must at least meet the
specifications required under
OSHA 29 CFR Part 1910.136 and
should provide good traction.
Covers may be disposed of after
use, facilitating decontamination.
General
Knife
Allows a person in fully-
encapsulating suit to cut his or
her way out of the suit in the
event of an emergency or
equipment failure.
Flashlight or Lantern
Enhances visibility in
buildings, enclosed spaces, and
the dark.
Should be carried and used with
caution to avoid puncturing the
suit.
Must be intrinsically safe or
explosion-proof for use in
combustible atmospheres. Sealing
the flashlight in a plastic bag
facilitates decontamination.
J-3
Adapted from Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities. October 1985. NIOSH/OSHA/USCG/EPA.
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Body Part Protected
Type of Clothing or Accessory
Description
Type of Protection
Use Considerations
General
(Continued)
Personal locator beacon
Two-way radio
Safety Belts, harnesses, and
lifelines
Orange vests or cones
Operated by sound, radio, or
light.
Enables emergency personnel
to locate victim.
Enables field workers to
communicate with support
personnel.
Enables personnel to work in
elevated areas or enter
confined areas and prevent
falls. Belts may be used to
carry tools and equipment.
Deflects vehicular traffic from
POTW activities.
Only electrical equipment
approved as intrinsically safe, or
approved for the class and group
of hazard as defined in Article 500
of the National Electric Code, may
be used.
Must be constructed of spark-free
hardware and chemical-resistant
materials to provide proper
protection. Must meet OSHA
standards in 29 CFR Part
1926.104.
J-4
Adapted from Occupational Safety and Health Guidance Manual for Ha^plnns Waste Site Activities. October 198S. NIOSH/OSHA/USCG/EPA
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APPENDIX K
ABBREVIATIONS AND GLOSSARY
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APPENDIX K
ABBREVIATIONS
ACGIH American Conference of Governmental Industrial Hygienists
BMP Best Management Practices
BPJ Best Professional Judgment
CFR Code of Federal Regulations
CGI Combustible Gas Indicator
CMSD Cincinnati Metropolitan Sanitary District
CMP Chemical Management Practices
FID Flame lonization Detector
IU Industrial Users
IDLH Immediately Dangerous to Life and Health
LEL Lower Explosive Limit
MSDS Material Safety Data Sheet
NIOSH National Institute for Occupational Safety and Health
NFPA National Fire Prevention Association
OSHA Occupational Safety and Health Administration
OVA Organic Vapor Analyzer
PEL Permissible Exposure Limits
PID Photo lonization Detector
POTW Publicly Owned Treatment Works
PPE Personal Protective Equipment
PPM Parts Per Million
SARA Superfund Amendments and Reauthorization Act
SCBA Self-Contained Breathing Apparatus
TLV Threshold Limit Values
TLV-C Threshold Limit Value - Ceiling
TLV-STEL Threshold Limit Value - Short Term Exposure Limit
TLV-TWA Threshold Limit Value - Time Weighted Average
UEL Upper Explosive Limit
WEF Water Environment Federation (formerly the Water Pollution Control Federation (WPCF))
K-l
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GLOSSARY
Action Level - A numerical limit of a chemical, biological, or radiological agent at which actions are taJcen to
prevent or reduce exposure or contact.
Aeration - The addition of air in the form of bubbles to a liquid.
Air stripping - A physical treatment process used to remove volatile substances from wastestreams by the transfer
of volatile pollutants from a high concentration in the wastestream into an air stream with a lower concentration of
the pollutant.
Best Management Practices (BMP) - Schedules of activities, prohibitions or practices, maintenance procedures, and
other management practices to prevent or reduce pollution discharges.
Best Professional Judgment (BPJ) - The highest quality technical opinion developed by a permit writer after
consideration of all reasonable available and pertinent data or information which forms the basis for the terms and
conditions of a permit.
Slowdown - The removal of accumulated solids in boilers to prevent plugging of boiler tubes and steam lines. In
cooling towers, the blowdown is used to reduce the amount of dissolved salts in the recirculated cooling water.
Chlorine detector - Usually a mixed oxide semi-conductor (similar to an oxygen meter), which is calibrated to detect
chlorine concentrations in the air.
Code of Federal Regulations (CFR) - A U.S. Government publication which contains finalized Federal regulations.
Combustible Gas Indicator - An instrument that measures the concentration of a flammable vapor or gas in air,
indicating the results as a percentage of the lower explosive limit (LEL) of the calibration gas.
Condensation - A chemical reaction in which water or another simple substance is released by the combination of
two or more molecules.
Equilibration - To maintain an equilibrium.
Flammable Liquid - A liquid with a flash point below 100°F and having a vapor pressure not exceeding 40 psig
absolute at 100°F.
Flashpoint - The minimum temperature at which vapor combustion will spread away from its source of ignition.
Fume - The paniculate, smoke-like emanation from the surface of heated metals. Also the vapors evolved from
the concentrated acids (sulfuric, nitric); from evaporating solvents; or as the result of combustion or any other
decomposition reaction.
Gas - A state of matter with a characterized by a very low density and viscosity (relative to liquids and solids);
comparatively great expansion and contraction with changes in temperature and pressure; ability to diffuse readily
into other gases; and ability to occupy with almost complete uniformity the whole of any container.
Gas/Vapor Toxicitv - Indicates the likelihood of adverse health effects when the time weighted average threshold
limit valve (TWA-TLV) is approached or exceeded.
Gas Chromatograph/Mass Spectrometer - Analytical instruments that determine presence and concentration of
substances in a liquid.
Henry's Law - A thermodynamic relationship which states that in a closed system the concentration of a constituent
in the vapor phase and the corresponding equilibrium concentration in the liquid phase are related by a constant.
This Henry's Law Constant is the ratio of the constituent's vapor pressure to its water solubility:
H = P^/S
K-2
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where: H = constituent's Henry's Law Constant, atm m3/ml
P^ = constituent's vapor pressure, atm
S = constituent's water solubility, ml/in3
Hydrogen Sulfide Detector - An instrument similar to an oxygen meter except that it is adjusted to sound an alarm
when a particular contaminant level is reached.
Lower Explosive Limit (LEL) - The point at which the concentration of a gas-in-air is sufficiently large to result
in an explosion if an ignition source is present.
Material Safety Data Sheet (MSDS) - A document which provides pertinent health and safety information and a
profile of a particularly hazardous substance or mixture.
Mitigation - Actions taken to prevent or reduce the severity of harm.
National Institute of Occupational Safety and Health (NIOSH) - A Federal agency that tests and approves safety
equipment for particular applications, with a primary goal to eliminate on-the-job hazards to the health and safety
of workers.
Occupational Safety and Health Act (OSHA) (1970) - A Federal law designed to protect the health and safety of
industrial workers.
Organic Vapor Analyzer (OVA) - A portable instrument used to detect a variety of organic compounds in air, soil,
and water.
Oxidation Reduction Reaction - A chemical transformation in which electrons are transferred from one chemical,
the reducing agent, to another chemical, the oxidizing agent. In oxidation-reduction, reactions involving the transfer
of oxygen from one molecule to another, the molecule losing the oxygen is the oxidizing agent and the molecule
gaining the oxygen is the reducing agent.
Oxygen Meter - An instrument that measures the atmospheric oxygen (OJ concentration directly by means of a
galvanic cell.
Sublimation - A process by which solids will volatilize.
Sulfur Dioxide Detector - An instrument similar to a chlorine detector except that it is calibrated to detect sulfur
dioxide concentrations in the air.
Teratogen - Any substance which tends to cause birth defects after conception.
Threshold Limit Value (TLV) - The average concentration of toxic gas or any other substance to which a normal
person can be exposed without injury during an average work week.
Threshold Limit Value - Ceiling (TLV-C) - The concentration that should not be exceeded during any part of the
working exposure. In conventional industrial hygiene practice, if instantaneous monitoring is not feasible, the TLV-
C can be assessed by sampling over a 15-minute period, except for those substances that may cause immediate
irritation when exposures are short.
Threshold Limit Value - Short-term Exposure Limit (TLV-STEL) - (1) Defined as a 15-minute TWA exposure
which should not be exceeded at any time during a workday even if the 8-hour TWA is within the TLV-TWA.
Exposures above the TLV-TWA up to the STEL should not be longer than IS minutes and should not occur more
than four times per day. There should be at least 60 minutes between successive exposures in this range. An
averaging period other than IS minutes may be recommended when s warranted by observed biological effects.
(2) The concentration to which nearly all workers can be exposed continuously for a short period of time without
suffering from irritation, chronic or irreversible tissue damage, or narcosis of a sufficient degree to increase the
likelihood of accidental injury, impair self rescue or materially reduce work efficiency. It supplements the time-
weighted average limit where there are recognized acute effects from a substance whose toxic effects have been
reported from high short-term exposures in either humans or animals.
K-3
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Threshold Limit Value - Time Weighted Average (TLV-TWA) - The time-weighted average concentration for a
normal 8-hour workday and a 40-hour workweek to which workers may be exposed, day after day, without adverse
effects.
Vapor - An air dispersion of molecules of a substance that is liquid or solid in its normal state; i.e., at standard
temperature and pressure. Examples are water vapor and benzene vapor. Vapors of organic liquids are also
loosely called fumes.
Vapor pressure - The pressure exerted by a vapor in equilibrium with its solid or liquid phase.
Volatilization - The process of forming vapor.
Water solubility - The ability of a substance to dissolve in water.
K-4
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APPENDIX L
BIBLIOGRAPHY
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BIBLIOGRAPHY
1. American Conference of Governmental Industrial Hygienists. 1990. 1990-199 IThreshold Limit Values
for Chemical Substances and Physical Agents and Biological Exposure Indices.
2. Bretherick, L. 1975. Handbook of Reactive Chemical Hazards. CRS Press, Cleveland, Ohio.
3. DOT, USCG, Office of Research and Development. Survey of Personal Protective Clothing and
Respiratory Apparatus. September 1974.
4. Hawley, G.G. 1981. Condensed Chemical Dictionary. VanNostrandReinhold,NewYork,NY. Tenth
Edition.
5. NFPA. Fire Protection Handbook. Section 8, Chapter 1. Quincy, MA.
6. NFPA. Flammable and Combustible Liquids Code. NFPA-30. Quincy, MA.
7. NFPA. Industrial Fire Handbook. Section 2, Chapter 20. Quincy MA.
8. NFPA. Life Safety Code. NFPA-101. Quincy, MA.
9. NFPA. Recommended Practice for Fire Protection in Wastewater Treatment and Collection
Facilities. NFPA-820. Quincy, MA. February 1990.
10. NIOSH. 1985. Pocket Guide to Chemical Hazards. DHHS (NIOSH) 85-114. September 1985.
11. NIOSH. 1981. Health Hazard Evaluation Report. HETA 81-207-945. Washington. D.C. August 1981.
12. NIOSH. OSHA. USCG. EPA. 1985. Occupational Safety and Health Guidance Manual for Hazardous
Waste Site Activities. October 1985.
13. Sax, N.I. 1975. Dangerous Properties of Industrial Materials. Van Nostrand Reinhold Company, New
York.
14. Swhope, A.D., Castas, P.P., Jackson, J.O., Weitzman, P J. 1985. Guidelines for Selection of Chemical
Protective Clothing (Second EditionX
15. U.S. EPA. 1991. Guidance Manual for Control of Slue Loadings to POTWs. OWEP. September
1991.
16. U.S. EPA. 1987. Development and Implementation of Local Discharge Limitations Under the
Pretreatment Program. OWEP. December 1987.
17. U.S. EPA. 1982. Fate of Priority Pollutants in Publicly Owned Treatment Works. EPA 440/1-82-303.
18. Water Pollution Control Federation. 1983. Safety and Health in Wastewater Systems. Manual of
Practice 1. Alexandria, VA. 1983.
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