United States
Environmental Protection
Agency
Office of Water Enforcement
and Permits
Washington, D.C. 20460
November 1987
Water
v>EPA Guidance Manual on the
Development and
Implementation of Local
Discharge Limitations Under
the Pretreatment Program
Volume 1
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GUIDANCE MANUAL ON THE DEVELOPMENT AND IMPLEMENTATION
OF LOCAL DISCHARGE LIMITATIONS UNDER
THE PRETREATMENT PROGRAM
VOLUME I
November 1987
U.S. Environmental Protection Agency
Office of Water
Office of Vater Enforcement and Permits
401 M Street, S.U.
Washington, DC 20460
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ACKNOWLEDGEMENTS
This document vas prepared under the technical direction of
Ms. LeAnne Hammer, Environmental Engineer, Program Development
Branch, Office of Water Enforcement and Permits, U.S. Environmental
Protection Agency. Assistance vas provided to EPA by Science
Applications International Corporation of McLean, Virginia, under
EPA Contract 68-01-7043, WA #P1-11. Mr. Larry Lai vas the SAIC
Work Assignment Manager; principle technical authors vere: Messrs.
Roger Claff, Larry Lai, Peter Trick, Ms. Ann Johnson and Mr. Eric
Washburn
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TABLE OF CONTENTS
Volume I
1. INTRODUCTION 1-1
1.1 PURPOSE OF THIS MANUAL 1-1
1.2 BACKGROUND 1-2
1.2.1 What Are Local Limits and Why Are They
Important 12
1.2.2 Studies Supporting the Need for Local
Limits 1-3
1.2.3 The Need for EPA Guidance to Support POTW
Local Limits Development 1-4
1.3 LEGAL BASIS FOR LIMITS DEVELOPMENT 1-5
1.3.1 Specific Statutory/Regulatory Background 1-5
1.3.1.1 Pretreatment Regulations 1-5
1.3.1.2 Implementation of General Prohibitions . . 1-7
1.3.1.3 Implementation of the Specific
Prohibitions 1-9
1.3.2 Other Considerations Supporting Local Limits
Development 1-10
1.3.3 Relationship of Local Limits to Categorical
Standards 1-11
1.4 POTW DEVELOPMENT OF LOCAL LIMITS 1-11
1.4.1 Overview of the Local Limits Process 1-12
1.4.2 Planning Considerations in Local Limits
Development 1-15
1.4.2.1 Updating Local Limits 1-15
1.4.2.2 Ongoing Monitoring Program 1-17
1.4.2.3 Selection of Alternative Allocation
Methods 1-17
1.4.2.4 Use of an Appropriate Control
Mechanism 1-18
1.4.2.5 Public Participation 1-19
1.5 ORGANIZATION OF THE MANUAL 1-19
2. IDENTIFYING SOURCES AND POLLUTANTS OF CONCERN 2-1
2.1 CONCERNS TO BE ADDRESSED 2-1
2.1.2 Water Quality Protection. . . 2-2
2.1.3 Sludge Protection 2-3
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TABLE OF CONTENTS (Continued)
Page
2.1.4 Operational Problems 2-3
2.1.5 Vorker Health and Safety 2-4
2.1.6 Air Emissions 2-5
2.2 CHARACTERIZING INDUSTRIAL DISCHARGES 2-9
2.2.1 Industrial User Discharges 2-9
2.2.2 RCRA Hazardous Vastes 2-12
2.2.3 CERCLA Vastes 2-13
2.2.4 Hauled Wastes 2-14
2.3 REVIEW OF ENVIRONMENTAL PROTECTION CRITERIA AND
POLLUTANT EFFECTS DATA 2-15
2.3.1 Environmental Protection Criteria and
Pollutant Effects Data 2-16
2.4 MONITORING OF IU DISCHARGES, COLLECTION SYSTEM,
AND THE TREATMENT PLANT TO DETERMINE POLLUTANTS
OF CONCERN 2-17
2.5 MONITORING TO DETERMINE ALLOWABLE HEADWORKS LOADINGS . . . 2-23
2.5.1 Sampling at the Treatment Plant 2-23
2.5.2 Establishing Monitoring Frequencies 2-24
2.5.3 Establishing Sample Type, Duration, and
Timing of Sample Collection 2-28
2.6 TOXICITY TESTING 2-29
2.6.1 Toxicity Reduction Evaluations (TREs) 2-30
3. LOCAL LIMITS DEVELOPMENT BY THE ALLOWABLE HEADWORKS
LOADING METHOD 3-1
3.1 GENERAL METHODOLOGY ' 3-1
3.2 DEVELOPMENT OF MAXIMUM ALLOWABLE HEADWORKS LOADINGS. ... 3-2
3.2.1 Allowable Headwords Loadings Based on
Prevention of Pollutant Pass Through 3-3
3.2.1.1 Compliance With NPDES Permit Limits. . . . 3-3
3.2.1.2 Compliance with Water Quality Limits . . . 3-4
3.2.2 Allowable Headworks Loadings Based on
Prevention of Interference with POTW
Operations 3-8
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TABLE OF CONTENTS (Continued)
Page
3.2.2.1 Prevention of Process Inhibition 3-8
3.2.2.2 Protection of Sludge Quality ....... 3-11
3.2.2.3 EP Toxicity Limitations 3-14
3.2.2.A Reduction of Incinerator Emissions .... 3-15
3.2.3 Comparison of Allowable Headworks Loadings 3-16
3.2.4 Representative Removal Efficiency Data 3-17
3.2.4.1 Representative Removal Efficiencies
Based on Mean Influent/Effluent
Data 3-18
3.2.4.2 Representative Removal Efficiencies
Based on Deciles 3-18
3.2.4.3 Potential Problems in Calculating
Removal Efficiencies 3-20
3.2.4.4 Literature Removal Efficiency Data .... 3-24
3.3 PROCEDURE FOR ALLOCATING MAXIMUM ALLOWABLE
HEADVORKS LOADINGS 3-26
3.3.1 Building in Safety Factors 3-27
3.3.2 Domestic/Background Contributions 3-28
3.3.3 Alternative Allocation Methods 3-30
3.3.3.1 Conservative Pollutants.- 3-31
3.3.3.2 Nonconservative Pollutants 3-37
3.4 REVIEWING TECHNOLOGICAL ACHIEVABILITY 3-38
3.5 PRELIM 3-38
4. LOCAL LIMITS DEVELOPMENT TO ADDRESS COLLECTION SYSTEM
PROBLEMS 4-1
4.1 IMPLEMENTATION OF SPECIFIC PROHIBITIONS 4-1
4.1.1 Fire and Explosion 4-1
4.1.1.1 Lower Explosive Limit (LEL)
Monitoring 4-2
4.1.1.2 Sample Headspace Monitoring 4-3
4.1.1.3 Flashpoint Limitation 4-4
4.1.1.4 Industrial User Management Practice
Plans 4-5
4.1.1.5 Screening Technique for Identifying
Flammable/Explosive Pollutant
Discharges 4-6
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TABLE OF CONTENTS (Continued)
4.1.2 Corrosion 4-9
4.1.3 Flow Obstruction 4-12
4.1.4 Temperature 4-12
4.2 WORKER HEALTH AND SAFETY 4-13
4.2.1 Headspace Monitoring 4-13
4.2.2 Industrial User Management Practice Plans 4-15
4.2.3 Screening Technique for Identifying Fume
Toxic Pollutant Discharges 4-15
4.2.4 POTW Worker Safety 4-19
5. INDUSTRIAL USER MANAGEMENT PRACTICES 5-1
5.1 INTRODUCTION 5-1
5.2 CHEMICAL MANAGEMENT PLANS 5-3
5.3 SPILL CONTINGENCY PLANS 5-6
5.4 BEST MANAGEMENT PRACTICES PLANS 5-8
5.5 LEGAL AUTHORITY CONSIDERATIONS 5-10
5.6 APPROVAL OF INDUSTRIAL USER MANAGEMENT PLANS 5-10
6. CASE-BY-CASE PERMITS - BEST PROFESSIONAL JUDGMENT (BPJ) .... 6-1
6.1 INTRODUCTION 6-1
6.2 APPLICATION OF BPJ 6-1
6.3 APPROACHES TO BPJ 6-2
6.3.1 Existing Permit Limits for Comparable
Industrial Facilities 6-3
6.3.2 Demonstrated Performance of the Industrial
User's Treatment System 6-5
6.3.3 Performance of Treatment Technologies as
Documented in Engineering Literature
(Treatability) 6-6
6.3.4 Adapting Federal Discharge Standards 6-10
6.4 REGULATORY CONSIDERATIONS FOR DEVELOPING BPJ LOCAL LIMITS. 6-12
REFERENCES
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LIST OF TABLES
Table Page
1-1 Comparison of Features Associated Vith Categorical
Standards and Local Limits 1-20
3-1 EPA Ambient Water Quality Criteria for Protection of
Aquatic Life 3-39
3-2 Activated Sludge Inhibition Threshold Levels 3-44
3-3 Trickling Filter Inhibition Threshold Levels 3-46
3-4 Nitrification Inhibition Threshold Levels 3-47
3-5 Anaerobic Digestion Threshold Inhibition Levels 3-48
3-6 Federal and Selected State Sludge Disposal Regulations
and Guidelines for Metals and Organics 3-50
3-7 EP Toxicity Limitations 3-53
3-8 Nickel Levels in Chattanooga POTV Influent, Effluent,
and Sludge (2/11-2/20/80) 3-54
3-9 Priority Pollutant Removal Efficiencies Through
Primary Treatment 3-55
3-10 Priority Pollutant Removal Efficiencies Through
Activated Sludge Treatment 3-56
3-11 Priority Pollutant Removal Efficiencies Through
Trickling Filter Treatment 3-57
3-12 Priority Pollutant Removal Efficiencies Through
Tertiary Treatment 3-58
3-13 Typical Domestic Wastewater Levels 3-59
4-1 Closed Cup Flashpoints of Specific Organic Chemicals 4-22
4-2 Discharge Screening Levels Based on Explosivity 4-23
4-3 Henry's Law Constants Expressed in Alternate Units 4-24
4-4 Discharge Screening Levels Based Upon Fume Toxicity 4-26
5-1 List of Commonly Used Solvents 5-11
6-1 Comparison of Combined Metals Data Base Vith Metal
Finishing Data Base 6-15
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LIST OF FIGURES
Figure Page
1-1 Overviev of Local Limits Process 1-13
2-1 Simplified Conceptual Flow Diagram for Determining
Pollutants of Concern 2-18
2-2 Detailed Flow Sheet for Chemical Specific Approach to
Identifying Pollutants of Concern to Treatment
Plant Operations 2-20
2-3 Toluene Loading to the Chattanooga, Tennessee POTV 2-26
2-4 Example Approach for a Hunicipal TRE 2-32
3-1 Example Distribution Plot of Removal Efficiency Data 3-21
3-2 Commonly Used Methods to Allocate Maximum Allowable
Industrial Loadings 3-32
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Volume II: Appendices
Appendix Page
A REFERENCES TO DOCUMENTS WHICH PROVIDE GUIDANCE TO POTVs IN
DEVELOPING TECHNICALLY BASED LOCAL LIMITS A-l
B AUGUST 5, 1985 EPA GUIDANCE MEMO ON LOCAL LIMITS
REQUIREMENTS FOR POTV PRETREATMENT PROGRAMS B-l
C MATRIX OF POLLUTANT OCCURRENCE IN INDUSTRIAL VASTESTREAMS C-l
D CURRENTLY AVAILABLE EPA DEVELOPMENT DOCUMENTS D-l
- Publications Available from the Industrial Technology
Division D-2
Publications Available from the Government Printing
Office (GPO) and/or the National Technical Information
Service (NTIS) D-ll
E NOTIFICATION OF HAZARDOUS WASTE ACTIVITY, RCRA E-l
FORM 8700-12
F A SUMMARY OF POTV RESPONSIBILITIES UNDER THE RESOURCE
CONSERVATION AND RECOVERY ACT (RCRA) F-l
G PHYSICAL/CHEMICAL CHARACTERISTICS OF TOXIC POLLUTANTS G-l
- Glossary of Terms G-l
- National Fire Protection Association (NFPA)
Classification Scheme (45) G-2
- Table G-l: "Hazard Classifications and Vapor Phase
Effects G-4
- Table G-2: Fate of Pollutants in POTVs G-ll
- Table G-3: Environmental Toxicity and Criteria G-16
H TOXIC ORGANIC POLLUTANTS H-l
- Clean Water Act Priority Pollutants H-2
- RCRA Appendix IX List H-5
I LOCAL LIMITS DERIVATION EXAMPLE 1-1
J SAMPLE HEADSPACE MONITORING ANALYTICAL PROCEDURE J-l
K EXAMPLE FORMAT FOR AN IU ASPP PLAN K-l
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LIST OF APPENDICES (Continued)
Appendix
L
TREATABILITY OF TOXIC POLLUTANTS
- Table L-l:
- Table L2:
- Table L-3:
- Table L-4:
- Table L-5:
- Table L-6
- Table L-7
- Table L-8
- Table L-9
Performance of Treatment Technologies in
Removing Metals and Cyanide
Performance of Tretment Technologies in
Removing Polynuclear Aromatic Hydrocarbons
Performance of Treatment Technologies in
Removing Aromatics
Performance of Treatment Technologies in
Removing Phenols
Performance of Treatment Technologies in
Removing Halogenated Aliphatics
Performance of Treatment Technologies in
Removing Phthalates
Performance of Treatment Technologies in
Removing Nitrogen Compounds
Performance of Treatment Technologies in
Removing Oxygenated Compounds
Performance of Treatment Technologies in
Removing Pesticides
- Limitations to the Application of Organic Chemicals
Treatment Technologies
REFERENCES
Page
L-l
L-l
L-7
L-13
L-18
L-22
L-31
L-34
L-35
L-36
L-37
M-l
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1. INTRODUCTION
1.1 PURPOSE OF THIS MANUAL
This manual provides guidance to municipalities on the development and
implementation of local limitations to control conventional, nonconventional,
and toxic pollutant discharges from nondomestic industrial users (IUs) to
Publicly-Owned Treatment Works (POTVs). This document is principally directed
toward POTV personnel responsible for local pretreatment program implementa-
tion. In addition, it is intended to assist POTVs which are not required to
develop local programs but must develop local limits to prevent recurrence of
problems and to ensure compliance with Federal, State and local requirements.
Coverage
This manual presents information on a wide range of issues associated
with local limits development and implementation including: (1) the legal and
regulatory bases for local limits; (2) the relationship of local limits to
other pretreatment regulatory controls; (3) approaches to identify pollutants
and sources warranting local limits control; (4) sampling and analysis to
support local limits development; and (5) several technically-based approaches
for local limits development.
In spite of the breadth of material addressed in this manual, it has one
primary objective to provide practical assistance to POTV personnel on
technically-based approaches for setting local limits. As such, greater
emphasis and more detailed information is given on scientific, engineering,
and operational issues integral to limits development, than on policy and
procedural matters. The reader is referred to several other EPA guidance
materials listed in Appendix A for more extensive information on programmatic
requirements on related topics such as pretreatment program development and
POTV acceptance of hazardous wastes. In addition, Appendix A provides
references to important EPA reports which contain further information on
technical issues key to local limits development (e.g., POTV removal perform-
ance; sampling methodologies, etc.).
1-1
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Supplementing this and other EPA guidance manuals, EPA has developed a
computer program known as PRELIM (for pretreatment limits) which derives local
limits based on a POTV's monitoring, operational, and literature data and
applicable environmental criteria. The PRELIM program is described in Section
3.5 of this manual. PRELIM (on floppy disk) and its accompanying user's
manual are available through EPA Headquarters Office of Vater Enforcement and
Permits (OWEP).
1.2 BACKGROUND
1.2.1 Vhat are Local Limits and Why are They Important?
As stated, the chief purpose of this manual is to assist POTV personnel
to develop and implement technically-based local limits. It may be useful to
briefly review what local limits are and why they are important as a pre-
treatment regulatory control. More detailed statutory/regulatory information
is then provided in Section 1.3 of this chapter.
The National Pretreatment Program was established to regulate the
introduction of pollutants from nondoraestic sources into Publicly-Owned
Treatment Works. Discharges targeted for regulation include those which will
interfere with the operation of a POTV, including interference with its sludge
digestion processes, sludge use or disposal; which will pass through the
treatment works; or which are otherwise incompatible with such works. In
addition, the program is intended to improve opportunities to reclaim
municipal and industrial wastewaters and sludges (see 40 CFR §§403.1 and
403.2). To accomplish these objectives the National Pretreatment Program
relies on a pollution control strategy with three elements:
National Categorical Standards: National technology-based standards
developed by EPA Headquarters, setting industry-specific effluent
limits
Prohibited Discharge Standards:
- General Prohibitions (403.5(a)) - National prohibitions against
pollutant discharges from any nondomestic user which cause pass-
through or interference
1-2
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B/834-545-01a/#4
- Specific Prohibitions (403.5(b)) - National prohibitions against
pollutant discharges from any nondomestic user causing: (1) fire or
explosion hazard; (2) corrosive structural damage; (3) interference
due to flov obstruction; (4) interference due to flow rate or
concentration; and (5) interference due to heat.
« Local Limits:
- Enforceable local requirements developed by POTVs to address
Federal standards as veil as State and local regulations.
The rationale behind this three-part strategy is, first, that categorical
standards provide nationally uniform effluent limits affording a technology-
based degree of environmental protection for discharges from particular
categories of industry. Second, the prohibited discharge standards recognize
the site-specific nature of the problems they are intended to address at
sewage treatment works ajid provide a broader baseline level of control that
applies to all IUs discharging to any POTV, whether or not the IUs fall within
particular industrial categories. Third, local limits are specific require-
ments developed and enforced by individual POTVs implementing the general and
specific prohibitions, and also going beyond them as necessary to meet State
and local regulations.
This approach ensures.that site-specific protections necessary to meet
pretreatment objectives are developed by those agencies best placed to
understand local concerns namely POTVs. In this scheme, POTV development
and implementation of local limits is the critical link in ensuring that
pretreatment standards protecting both the local treatment works and local
receiving environment are applied.
1.2.2 Studies Supporting the Need for Local Limits
Several recent studies by EPA underscore the importance of local limits
to control site-specific plant and environmental impacts. Results from the
Agency's Complex Effluent Toxicity Test Program and State studies indicate
that many municipal effluents cause instream toxicity due to industrial
discharges to POTVS [52 and 53]. The State of North Carolina, for example,
found that 32 percent of POTVs tested had effluents with some degree of acute
toxicity, often attributable to industrial discharges of pollutants not
regulated by categorical standards.
1-3
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In a major study to Congress on hazardous waste discharges to POTVs (see
Appendix A) EPA found that vhile categorical standards had been effective in
reducing hazardous metals loadings and, to a lesser extent, some toxic
organics loadings to sewage treatment plants, significant amounts of hazardous
constituents will be discharged to municipalities even after full implementa-
tion of Federal categorical pretreatment standards. Documented effects
associated with these industrial discharges included adverse water quality
impacts, sludge contamination, potential degradation of raw drinking water,
air emissions of volatile organic compounds contributing to ozone nonattain-
ment, fires and explosions, sewer corrosion, endangerment of worker health and
safety, and loss of life.
Among its major conclusions, the Domestic Sewage Study recommended
modification of the prohibited discharge standards to improve control of char-
acteristic hazardous wastes and solvents and improvement/implementation of
local limits at the POTV level, particularly to control the discharge of toxic
organic constituents.
1.2.3 The Need for EPA Guidance to Support POTV Local Limits Development
Both in local program design and in implementation, POTV adoption of
local limits is pivotal to the accomplishment of effective pretreatment
controls. The Pretreatment Implementation Review Task Force (PIRT, a work
group made up of representatives from municipalities, industries, States,
environmental groups and EPA Regions to provide the Agency with recommenda-
tions on day-to-day problems faced by POTVs, States, and industries in
implementing the Pretreatment Program) found that, "defensible local limits
are the cornerstone of an effective POTV Pretreatment Program. Yet some POTV
representatives do not understand the relationship between categorical
pretreatment standards and local limits, or even how to develop local limits."
(p. 5, Pretreatment Implementation Review Task Force, Final Report to the
Administrator, January 30, 1985, Office of Vater Enforcement and Permits, U.S.
EPA.)
PIRT concluded that EPA should issue a policy statement and provide
technical guidance to facilitate development of local limits by POTVs. On
1-4
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August 5, 1985, EPA issued a memorandum clarifying local limits requirements
for POTV programs. The full text of the memorandum is provided in Appendix B.
As mentioned previously, EPA has also developed the computer model, PRELIM,
and a companion user guide to assist localities in local limits calculation.
This manual represents the next step in providing municipalities with the
requisite technical expertise to develop technically-based local limits.
1.3 LEGAL BASIS FOR LIMITS DEVELOPMENT
In order to provide a clear understanding of local limits, this chapter
summarizes the legal and regulatory bases for their development. It also
explains the relationship between local limits and federal categorical
pretreatment standards in controlling pollutant discharges to POTVs.
1.3.1 Specific Statutory/Regulatory Background
The statutory basis for the development of the National Pretreatment
Program is derived from the Federal Water Pollution Control Act of 1972.
Section 307 of the Act required EPA to develop pretreatment standards designed
to prevent the discharge to POTVs of pollutants "which interfere with, pass
through, or are otherwise incompatible with such works." When the Act was
amended in 1977, more pretreatment requirements were added in Section 402. At
that time, POTWs became responsible for establishing local pretreatment
programs to ensure compliance with the pretreatment standards.
1.3.1.1 Pretreatment Regulations
EPA developed the General Pretreatment Regulations (40 CFR 403) to
implement the requirements of Section 402. As discussed briefly earlier, the
General Pretreatment Regulations establish general and specific prohibitions
which are implemented through local limits. The regulations relating to each
of these elements are set forth below:
A.(i) General Prohibitions
Section 403.5(a)(1) General prohibitions. A user
may not introduce into a P0TW any pollutant(s) which
cause Pass-through or Interference. These general
prohibitions and the specific prohibitions in paragraph
(b) of this section apply to each user introducing
1-5
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pollutants into a POTV whether or not the source is
subject to other National Pretreatment Standards or any
National, State, or local Pretreatment Requirements.
(ii) Definition of Pass Through
[n] The term "Pass Through" means a Discharge which
exits the POTV into waters of the United States in
quantities or concentrations which, alone or in conjunc-
tion with a discharge or discharges from other sources,
is a cause of a violation of any requirement of the
POTV's NPDES permit [including an increase in the magni-
tude or duration of a violation]. Section 403.3(n)
(iii) Definition of Interference
ti1 The terra "Interference" means a Discharge which,
alone or in conjunction with a discharge or discharges
from other sources, both:
[1] Inhibits or disrupts the POTV, its treatment
processes or operations, or its sludge processes, use or
disposal; and
[2] Therefore is a cause of a violation of any
requirement of the POTV's NPDES permit [including an
increase in the magnitude or duration of a violation] or
of the prevention of sewage sludge use or disposal in
compliance with the following statutory provisions and
regulations or permits issued thereunder [or more strin-
gent State or local regulations]: Section 405 of the
Clean Vater Act, the Solid Waste Disposal Act [SVDA]
[including Title II, more commonly referred to as the
Resource Conservation and Recovery Act [RCRA], and
including State regulations contained in any State sludge
management plan prepared pursuant to Subtitle D of the
SVDA], the Clean Air Act, the Toxic Substances Control
Act, and the Marine Protection, Research and Sanctuaries
Act. Section 403.3(1)
B. Specific Prohibitions
Section 403.5(b) Specific prohibitions. In addi-
tion, the following pollutants shall not be introduced
into a POTV:
[1] Pollutants which create a fire or explosion
hazard in the POTV;
[2] Pollutants which will cause corrosive structural
damage to the POTV, but in no case Discharges with pH
lower than 5.0, unless the works is specifically designed
to accommodate such Discharges;
[3] Solid or viscous pollutants in amounts which
will cause obstruction to the flow in the POTV resulting
in Interference;
1-6
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[4] Any pollutant,including oxygen demanding pollu-
tants [BOD, etc.] released in a Discharge at a flow rate
and/or pollutant concentration which will cause Interfer-
ence with the POTV.
[5] Heat in amounts which will inhibit biological
activity in the POTV resulting in Interference, but in no
case heat in such quantities that the temperature at the
POTV Treatment Plant exceeds 40°C [104°F] unless the
Approval Authority, upon request of the POTV, approves
alternate temperature limits.
C. Implementation
Section 403.5(c) of the General Pretreatment Regulations requires the
implementation of the General and Specific Prohibitions through the local
limits process under two specific circumstances:
1. POTVs with local pretreatment programs "shall develop and enforce
specific limits to implement the prohibitions listed in §403.5(a) and
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some POTV permits include criteria for sludge use or disposal practices but
many do not yet incorporate sludge criteria. Sludge requirements may be
contained in State or Federal regulations and/or State-issued sludge use or
disposal permits. Section 406 o£ the Water Quality Amendments of 1987
amended 405(d) of the Clean Water Act to require the EPA Administrator "to
impose conditions in permits issued to publicly owned treatment vorks under
section 402 of this Act or take such other measures ... to protect public
health and the environment from any adverse effects which may occur from toxic
pollutants in sewage sludge." This permitting of sewage sludge in municipal
NPDES permits is to occur prior to promulgation of the sludge technical
criteria currently under development by the Office of Water at EPA. Section
406 also provides for implementation of the new sludge standards, once
promulgated, through NPDES permits. Thus many municipalities will soon have
sludge conditions in their Federal or State NPDES permits, if not already
present.
In summary, the effluent limits, water quality and sludge protection
conditions, toxicity requirements and 0&M objectives found in municipal NPDES
permits as veil as other applicable sludge requirements establish the
objectives that POTWs must meet in order to prevent pass through and inter-
ference. To the extent that pass-through or interference may occur, either in
part or in whole, as a result of inadequately treated industrial discharges
from any user, POTWs must develop local limits.
Many cities still only have specific NPDES permit provisions regulating
removal efficiencies and concentrations for conventional pollutants (e.g.,
biological oxygen demand, suspended solids) pH, and fecal coliform. As
acknowledged in the Preamble to the interference and pass through definitions,
EPA recognizes that the regulatory scheme for achieving water quality goals
through effluent limitations in NPDES permits has not yet been fully
implemented. Many States do not yet have numerical water quality criteria for
toxic or nonconventional pollutants of concern, although all States have a
narrative prohibition against the discharge of toxic pollutants in toxic
amounts. That standard should be reflected in the POTW's permit either by
general or specific limitations. Therefore, a violation of the prohibition on
toxics in toxic amounts due to industrial discharges is a strong rationale for
POTV local limits development.
1-8
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EPA expects* that increasing numbers of POTV permits will contain limits
on toxic pollutants contributed by industrial users in addition to the usual
limits on BOD, TSS and pH. In the issuance of third-round permits nov
underway, EPA has emphasized the application of the "Policy on Water Quality-
Based Permit Limits for Toxic Pollutants" (49 FR 9016, March 9, 1984). This
policy calls for an integrated strategy to address toxic and nonconventional
pollutants through both chemical and biological methods. Vhere State
standards contain numerical criteria for toxic pollutants and the POTV's
effluent contains those pollutants, limits to achieve the water quality
standards may be required in NPDES permits. Vhere State numerical criteria
are not yet available, NPDES permitting authorities are expected to use a
combination of both biological techniques and available data on specific
chemical effects to assess toxicity impacts and human health hazards and then
develop permit conditions that establish effluent toxicity limits or specific
chemical limits as appropriate. POTVs will then be expected to develop local
limits to ensure these permit limits will not be violated.
1.3.1.3 Implementation of the Specific Prohibitions
The specific prohibitions forbid the discharge of pollutants which cause
fire or explosion hazard, corrosive structural damage, obstruction of flow,
interference, or inhibition of biological activity due to excessive heat.
Enforcement of these prohibitions is a precondition of pretreatment program
approval, and critical prerequisites for meeting permit limits, protecting
workers and maintaining a well-operated treatment plant.
POTV sewer use ordinances typically contain either definitions or local
limits implementing these specific prohibitions. Definitions may simply
consist of the descriptive language from 40 CFR 403.5(b) given above, or may
quantitatively define prohibitions, such as by correlating fire/explosion
hazard to specific readings on an explosimeter. Such quantitative limits
avoid ambiguity and are effective in terms of POTV enforcement and IU
compliance.
Whereas the regulations concerning the specific discharge prohibitions
address in a general way certain problems, which must be prevented,
1-9
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numeric limits are often pollutant-specific and can be more easily implemented
and enforced. Section 4.1 outlines the procedures POTVs can follow in
establishing specific local limits to define and implement the very important
concerns addressed in the specific discharge prohibitions.
1.3.2 Other Considerations Supporting Local Limits Development
The above discussion enumerated Federal regulatory requirements which
mandate local limits development. It is important to note that the Federal
Clean Water Act and the General Pretreatment Regulations specifically endorse
more extensive requirements based on State and/or local law (40 CFR 403.4).
POTVs should evaluate their State permits to identify additional State
requirements in areas such as solid waste management, worker health and
safety, hazardous waste acceptance, and POTV air emissions which may
necessitate local limits development.
Two very important concerns that may necessitate local limits develop-
ment, depending on individual permit and sludge disposal requirements, and
State and local regulations are: preventing fume toxicity to workers and
reducing POTV air emissions. POTVs have been aware of fume toxicity health
problems associated with sewer worker exposure to volatile compounds and have
implemented local limits to reduce risks. Cities with air pollution problems
might well consider local limits to reduce air emissions both in the col-
lection system and the headworks due to industrial discharges containing
volatile organic compounds (VOCs). POTVs that practice sludge incineration
may be regulated under the Clean Air Act. Information on developing local
limits to address air pollution and fume toxicity problems is contained in
later sections of this manual.
Finally, it should be emphasized that local limits should be preventive
rather than reactive. Accordingly, EPA recommends that POTVs consider all
relevant plant and environmental information in evaluating the need for local
limits. Vhere POTVs can anticipate problems they should set local limits
without waiting for problems to occur.
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1.3.3 Relationship of Local Limits to Categorical Standards
PIRT suggested in its findings that many POTVs misunderstood the rela-
tionship betveen local limits and categorical standards, thereby hindering
effective implementation of pretreatment standards. Categorical standards and
local limits are distinct and complementary types of pretreatment standards."
Promulgation of a categorical standard by EPA in no way relieves a munici-
pality from its obligations to evaluate the need for, and to develop, local
limits to meet the general and specific prohibitions in the General
Pretreatment Regulation. As suggested earlier, categorical standards are
developed to achieve a nationally-uniform degree of water pollution control
for selected industries and pollutants. Local limits are intended to prevent
site-specific plant and environmental problems resulting from any nondomestic
user.
In many cases POTVs may impose local limits which regulate categorical
industries more stringently and/or for more pollutants than are regulated in
the applicable categorical standard to afford additional plant or environ-
mental protection. In this case, the local limit supersedes the categorical
standard as the applicable pretreatment standard. As a corollary, however, a
less stringent.local limit does not relieve a categorical industry from its
obligation to meet the Federal s'tandard. The central point to be remembered
is that the existence of a Federal categorical standard should not deter a
city from its obligation to evaluate discharges from all nondomestic users, to
identify problem pollutants and to adopt more stringent technically-based
local limits, where necessary.
With this understanding in mind, Table 1-1 highlights major differences
between categorical standards and local limits. Generalizations that may be
drawn from this Table are that local limits are broader in scope, may be more
diverse in form, and draw upon POTV discretion and judgment for development.
1.4 POTV DEVELOPMENT OF LOCAL LIMITS
This section provides a brief overview of the steps associated with local
limits development. The audience for this discussion includes POTVs with
local pretreatment programs and those which, though not required to develop
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programs, must develop local limits to prevent recurring industry-related
problems. Moreover, POTVs using this manual may be at different stages in
local limits development from first time development, to complete
reeyaluation and revision, to development of limits for additional pollutants.
They likely possess different technical resources at their disposal. As such,
this discussion is intended to give a general sense of the local limits
process and to serve as a guide for the more detailed technical discussions
which follow in subsequent chapters.
1.4.1 Overview of the Local Limits Process
An overview of the local limits development process is presented in
Figure 1-1. Local limits development requires a POTV to use site-specific
data to identify pollutants of concern which might reasonably be expected to
be discharged in quantities sufficient to cause plant or environmental
problems. The process for identifying pollutants of concern, through
characterizing industrial discharges, monitoring of POTV influent, effluent
and sludge, and reviewing pollutant effects on plant operations, and environ-
mental protection criteria, is discussed in detail in Chapter 2.
Once the pollutants of concern and the sources discharging them have been
identified, the POTV must select the most effective technical approach for
limits development. As is shown in Figure 1-1, several methods are available
depending on the nature of the potential problem. Each approach is described
briefly below.
Allowable Headworks Loading Method: In this procedure, a POTV
converts environmental and plant protection criteria into maximum
allowable headworks loadings that, if received, would still enable the
POTV to meet environmental limits and avoid plant interference.
Allowable headworks loadings are calculated by the POTV on a
pollutant-by-pollutant basis for each plant process and environmental
objective relevant to the POTV. For example, the maximum amount of
zinc which can safely be received by the plant without inhibiting
sludge digestion is calculated, as well as the maximum zinc load which
would allow for compliance with the POTV's NPDES permit limits. This
procedure is performed for each criteria and the resulting loadings
are compared. The lowest value (mass loading) for each pollutant is
identified and serves as the basis for identifying the need for a
local limit. If the allowable headworks loading for a particular
pollutant is veil above that loading currently received by a POTV, a
local limit may not be necessary. However, if POTV influent loadings
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Review Plant Operations and
Environnental Criteria to Deteraine
the Need for Local Liaits
e Coapare POTW renoval efficiency,
effluent, sludge values with NPDES
permit liaits and other applicable
State requireaents
e Compare influent values with
actual and/or literature data on
threshold inhibition levels
e Coapare worker exposures and air
eaissions with safety and air
criteria
e Build in safety factor to allow
for growth
e Screen pollutants for local liaits
technical analysis
See Sections 2.1 and 2.3
Deteraine the Sources, Character,
and Voluae of III Pollutant
Contributions to POTW
e Conduct/review IWS data
e Perfora IU discharge and POTW
collection systea saapling
e Perfora influent, effluent,
sludge saapling/analysis,
toxicity testing
Heview IU aonitonng reports
e Review new IU perait applications
See Sections 2.2 and 2.4
Select and Iapleaent Technical
Approach for Liaits Developaent
e Perfora allowable headworks
allocation analysis (Chapter 3)
or/and;
e Perfora collection systea analysis
(Chapter 4) or/and;
e Evaluate industrial user aanage-
aent practices or/and;
e Develop case-by-case perait liait
See Chapters 3, 4, 5, and 6
riGUKB 1-1. OVKHVIKW OF LOCAL. LIMITS PBOCKSS
-------
approach or exceed the allowable headvorks loading, the need for a
limit will have been established.
Collection System Approach; Using this approach, a POTV can identify
pollutants vnich may cause air releases, explosive conditions, or
otherwise endanger worker health and safety. These pollutants can
then be controlled by numeric local limits and/or industrial user
management practice plans. This approach requires system sampling and
analysis to identify pollutants present in the collection system.
Pollutants detected in the collection system are evaluated to deter-
mine their propensity to change from a liquid phase to a gaseous
phase. This screening evaluation is performed using the Henry's Law
Constant for each pollutant, a measure of the compound's equilibrium
in water. For those pollutants shown to volatilize, comparisons are
then made with worker health exposure criteria, threshold limiting
values (TLVs), and lower explosive limits (LELs) (the minimum con-
centration in air which will combust or explode). Where threshold
limiting values or lower explosive limits are predicted to be exceeded
as a result of a pollutant discharge, the need for further monitoring
to confirm the problem and, if appropriate, a local limit or manage-
ment practice plan is indicated. The use of flashpoint limits (the
minimum temperature at which the combustion of a compound will
propagate away from an ignition source) to prevent the discharge of
ignitable wastes is also recommended.
Industrial User Management Practice Plans: This approach embodies
several methods a POTV may use to reduce industrial user pollutant
discharges by requiring IUs to develop management practice plans for
handling of chemicals and wastes. The methods available are
particularly effective for control of episodic or highly variable
discharges such as spills, and batch and slug discharges. To accom-
plish this approach, a POTV takes steps to understand an industrial
user's operations by monitoring discharges, inspecting facilities, and
reviewing IU reports. Depending on the nature of the discharge
problem, the POTV then requires the IU to develop and implement a
management plan as an enforceable pretreatment requirement to reduce
or eliminate the impacts associated with the discharge. Appropriate
management plans may address spill prevention and containment,
chemical management practices (e.g., chemical substitution, recycling,
and chemical segregation) and best management practices addressing
housekeeping practices. A management practice plan requirement can be
viewed as a type of narrative local limit. POTVs may include numeric
local limits as a part of, or in addition to, industrial user
management practices to enhance their effectiveness.
Case-by-Case Permitting: In this approach a POTV sets numeric local
limits based on removals which can be achieved with available
technology(ies) which are known to be economically affordable. POTV
engineers establish specific limits based on their best professional
judgment making use of data on removal efficiencies and economic
achievability for pollution control from comparable industries/
discharges. This approach is particularly suitable where effects data
for specific pollutants is not sufficient to use other approaches, but
where a degree of control is indicated as a result of observable
effects (e.g., toxicity testing, fishkills, plant inhibition, etc.)
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Some of these approaches are suited to specific problems and pollutants (e.g.,
pass-through is best addressed by the allovable headvorks loading method).
Others can be used in conjunction with each other (e.g., allowable headworks
loading method with industrial user management practices). The technical
approach used by a POTV to develop local limits is principally a local
decision, provided that the resulting limits are enforceable and
scientifically-based.
1.4.2 Planning Considerations in Local Limits Development
The preceding discussion presented an overview of technical bases for
local limits development process, highlighting technical approaches which a
POTV may use to establish local limits. In this section, planning issues
associated with local limits are introduced. Issues discussed here include:
1) the need to update and revise local limits; 2) institution of an ongoing
monitoring program to support local limits development; 3) selection of local
limits allocation methods; 4) employment of an effective control mechanism to
impose local limits; and 5) ensuring public participation. These topics,
while divergent in subject matter, represent critical considerations in
planning and implementing local limits. Proper attention to these issues
early on in the limits development process may assist POTVs in analyzing
options, making effective use of resources and minimizing or eliminating the
need for frequent local limits revisions.
1.4.2.1 Updating Local Limits
Local limits development is not a one-time event for POTVs. Local limits
should be periodically reviewed and revised as necessary to respond to changes
in Federal or State regulations, environmental protection criteria, plant
design and operational criteria, and the nature of industrial contributions to
POTV influent. To the extent that a POTV can anticipate changes and develop
appropriately protective local limits, the need to revise a particular local
limit in the future may be reduced. For example, if a POTV knows or can
anticipate that economic growth is occurring in its service area, it should
factor in a growth margin so that all of the allowable headworks loading is
not used up by existing industrial users. Otherwise, additional industrial
hook-ups would be prohibited and/or local limits would have to be modified.
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Similarly, if a POTV anticipates changing its sludge disposal practices in the
near future, the POTV should develop local limits nov vhich are protective of
any more restrictive sludge use. By use of foresight, POTVs can extend the
validity of their local limits to the projected term of an IU permit
(typically one to five years). Effective planning vill eliminate frequent
local limits modifications vhich may tax POTV resources and weaken IU
compliance efforts.
POTVs, nonetheless, should evaluate the need to update local limits when
there are changes in: (1) the limiting criteria on vhich local limits are
based, and/or (2) the flow rate and characteristics of industrial contrib-
utions (including connection of additional industrial users). Examples of
potential changes that would affect criteria used in deriving local limits
include:
Changes in NPDES permit limits to include additional or more restric-
tive toxic pollutant limits, including organic pollutants
Changes in water quality limits including toxicity requirements
Changes in sludge disposal standards or POTV disposal methods
Modifications to the treatment plant, causing changes in the process
removal efficiencies and tolerance to inhibition from pollutants
Availability of additional site-specific data pertaining to pollutant
removal efficiencies and/or process inhibition.
Potential changes in industrial contributions include:
Connection to the POTV of new industrial users
Addition of new processes at existing industrial users
Shutdown of industrial users or discontinuation of process discharges
Changes to existing industrial user processes, including chemical
substitutions, expected to alter pollutant characteristics and
loadings to the POTV
Alteration of pretreatment operations.
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The industrial waste survey should be reviewed periodically to determine
if any of the above factors have substantially changed. Upon conducting such
a review, the POTV should update its existing local limits as necessary and/or
develop new local limits to cover additional pollutants. Any such changes in
local limits are considered to be a modification of the POTV's pretreatment
program, and as such need to be submitted to, and approved by, the Approval
Authori ty.
EPA encourages POTVs to reevaluate local limits that were adopted without
a sound technical basis, particularly if these limits were so poorly justified
that they could be unenforceable by the POTV. In some cases, it may be
appropriate for a POTV to relax limits that fall into this category. However,
the POTV must first demonstrate that the revised limits will satisfy all of
the minimum Federal and State requirements and will adequately protect in-
stream water quality and sludge quality. If the analysis does show that local
limits can be relaxed, the POTV should determine whether the relaxation will
result in new or increased discharges from IUs which will affect the volume or
character of the POTV influent or effluent. If so, they must notify the NPDES
permitting authority pursuant to AO CFR 122.42(b). A determination will then
be made as to whether the discharge can be allowed, consistent with the
State's antidegradation policy, 40 CFR §131.12, and the Clean Vater Act §303.
1.4.2.2 Ongoing Monitoring Program
Critical to successful development and updating of local limits is the
existence of comprehensive data on IU discharges, conditions in the collection
system, and characteristics of the POTV influent, effluent, and sludge.
Sections 2.4 and 2.5 of this manual outlines basic monitoring requirements
necessary to support local limits development. An adequate monitoring program
may not be provided by existing POTV efforts. By identifying additional
requirements early and phasing in supplemental improvements, POTVs will have
sufficient data to update and revise local limits as changes dictate.
1.4.2.3 Selection of Alternative Allocation Methods
POTVs which develop local limits may choose a variety of allocation
methods. As will later be discussed in Section 3.3, EPA does not dictate any
1-17
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single specific local limits implementation procedure. Rather, local limits
may be allocated and imposed in any number of ways, such as:
Uniform maximum allowable concentrations based on the total flow from
all industrial users
Concentration limits based on allocation of pollutant loadings to only
those industries contributing the pollutant of concern
Proportionate reduction of the pollutant by each industrial user that
discharges the pollutant, based on the industrial user's mass loading
Technology-based limitations applied selectively to the significant
dischargers of a chosen pollutant
The method of control remains the POTV's option, so long as the method
selected does not result in an exceedance of the maximum allowable headworks
loadings. Choice of a particular allocation method may have consequences in
terms of the control mechanism a POTV uses to impose the limit. This is
discussed briefly in the following subsection.
1.4.2.4 Use of an Appropriate Control Mechanism
Another planning consideration in local limits development is how the
POTV will impose its limits on an industrial user. POTVs have discretion in
the selection of a control mechanism through which local limits are applied to
industrial users (e.g., ordinance, permit, order, etc.) However, it is highly
unlikely that an ordinance-only system would be adequate with any allocation
method except the uniform maximum allowable concentration method. An
individual control mechanism such as a permit is necessary for effective
operation in all but the simplest of IU-POTV relationships.- Even in those
situations where there is one uniform set of local limits for all IUs, an
individual control mechanism is desirable to specify monitoring locations and
frequency, special conditions such as solvent management plans or spill
prevention plans, applicable categorical standards, reporting requirements and
to provide clear notification to IUs as required by 40 CFR §403.8 of the
General Pretreatment Regulations.
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1.4.2.5 Public Participation
A final planning consideration that POTVs should remember is that Federal
regulations require POTVs to provide individual notice and an opportunity to
respond to affected persons and groups before final promulgation of a local
limit [40 CFR §403.5(c)(3)]. POTVs should allow .sufficient time in their
limits development process to allow for public participation. In addition,
the possibility of technical challenges on the rationale for a particular
local limit during public participation argues for thorough documentation and
recordkeeping as a part of a POTV's local limits development process.
1.5 ORGANIZATION OF THE MANUAL
As suggested originally, the principal focus of this manual is on
technical issues associated with local limits development. Each of the
following chapters provides specific information on technical steps for limits
development:
Chapter 2 - Identifying Sources and Pollutants of Concern - details
environmental and plant concerns to be addressed; identifies key
sources warranting attention and ways to characterize nondomestic
discharges; specifies sources of key environmental and plant
protection criteria and describes appropriate sampling and analysis,
and toxicity testing methods which may be employed.
Chapter 3 - Local Limits Development by the Allowable Headworks
Loading Method - describes allowable headworks loading methods;
specifies techniques to prevent pass through and interference;
discusses alternative allocation scenarios.
Chapter 4 - Local Limits Development to Address Collection System
Problems - describes techniques to set local limits to prevent fire
and explosion, corrosion, flow obstruction, temperature and worker
health and safety concerns in POTV collection systems.
Chapter 5 - Industrial User Management Practices - outlines approaches
to control problem pollutants through solvent management, spill
prevention and chemical management plans.
Chapter 6 - Case-by-Case Permitting of Industrial Users - provides an
overview of methods to establish technology-based limits for IU
discharges on a case-specific basis.
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TABLE 1-1. COMPARISON OP FEATURES ASSOCIATED WITH CATEGORICAL STANDARDS AND LOCAL LIMITS
IARACTERISTIC
CATEGORICAL STANDARDS
LOCAL LIMITS
;ency Responsible for
Development
>tential Sources Regulated
)jective
)llutants Regulated
isis
jplicabi lity
ype of Limit
EPA
Industries specified in Clean
Water Act (CWA) or by EPA
Baseline requirement
Primarily priority pollutants
listed under Section 307
of CWA, although not limited
to priority pollutants
Technology (BAT or NSPS)
or Management Practice
(e.g., solvent management
plan)
oint of Application
Apply to particular regulated
vastestreams vithin certain
industrial subcategories
Several: production-based
or concentration-based
numerical limits, discharge
prohibition, or management
practice plan requirements
Usually end of regulated
process
POTWs (Control Authority)
All nondomestic users
Local environmental and plant
objectives
All pollutants - priority/non-
priority
Any technically-based method
including:
Allowable headvorks loading
method
Toxicity reduction evaluation
Technology-based
Management practice
Apply to all nondomestic users
either uniformly or case-by-case
Several: production-based
or concentration-based
numerical limits, discharge
prohibition, or management
practice plan requirements
Usually at point of discharge to
collection system
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2. IDENTIFYING SOURCES AND POLLUTANTS OF CONCERN
Activities conducted for the development of local limits consist of
identifying areas of concern, gathering requisite data on the sources and
pollutants of concern, and calculating local limits. During development of
local limits, the POTV:
Step 1 Identifies the concerns it must address through local limits develop-
ment in order to meet Federal, State and local requirements;
Step 2 Identifies the sources and pollutants which should be limited in order
to address those concerns as follows:
Characterizing industrial discharges
Review of applicable environmental protection criteria and
pollutant effects data
Monitoring of IU discharges, POTV collection system and treatment
plant.
Step 3 Calculates local limits for the identified pollutants of concern.
Section 2.1 of this Chapter identifies the various concerns that may be
addressed by local limits. Sections .2.2 through 2.A discuss the three
elements of identifying sources and pollutants of concern. The third step
listed above, calculating local limits, is discussed in Chapters 3 through 6.
2.1 CONCERNS TO BE ADDRESSED
A POTV's local limits must, at a minimum, be based on meeting the
statutory and regulatory requirements as expressed in the Clean Water Act and
General Pretreatment Regulations and any applicable State and local
requirements, as stated in Chapter 1. Since individual NPDES permit condi-
tions, sludge disposal practices, and State and local requirements vary from
POTV to POTV, there are a variety of concerns which potentially must be
addressed through local limits. As part of the process of developing local
limits, it will be useful for the POTV at the outset, to list the concerns or
objectives that it needs to address. The types of concerns that a POTV is
likely to be required to address as a result of Federal, State or local
requirements include the following:
2-1
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Vater quality protection
Sludge quality protection
Operational problems
Worker health and safety
Air emissions.
This section discusses each of these concerns in some detail. Later sections
of the manual provide technical guidance that should be useful in developing
local limits to address these concerns.
2.1.2 Vater Quality Protection
POTVs are required to prohibit IU discharges in amounts that result in
violation of vater quality-based NPDES permit limits. These permit limits are
often based on specific water quality standards and are generally expressed as
numeric standards. Additionally, many permits include a permit requirement
similar to the following: "All waters shall be maintained free of toxic
substances in concentrations that are toxic to or that produce detrimental
physiological responses in human, plant, animal, or aquatic life." Thus, based
on this narrative toxicity prohibition, POTVs must identify additional
pollutants of concern or comply with specific toxicity limitations.
POTVs should utilize toxicity-based approaches and chemical specific
approaches involving applicable water quality standards or criteria in order
to comply with such requirements. Vater quality criteria have been developed
by EPA, and implemented as standards by many State agencies. Vater quali ty
criteria/standards are often based on stream reach classification, hardness,
and other factors. The POTV should obtain receiving stream vater quality
standards or criteria by contacting the appropriate State agency. Section
3.2.1.2 discusses procedures for developing local limits that are based on
vater quality standards/criteria.
In addition to developing local limits based on vater quality standards/
criteria, POTVs may need to develop local limits that are based on reducing
aquatic toxicity. A brief discussion of toxicity reduction evaluations is
presented in Section 2.6.1.
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2.1.3 Sludge Protection
POTVs are required to prohibit IU discharges in amounts that cause
violation of applicable sludge disposal or use regulations, or restrict the
POTV from using its chosen sludge disposal or use option. The importance of
this requirement is underscored by the recent Clean Water Act amendments which
require the incorporation of sludge criteria and requirements into all NPDES
permits when they are issued or reissued. EPA has prepared interim guidance
on what presently must be incorporated into permits to comply with these
amendments. In addition, the Agency is developing new regulations that will
set forth pollutant-specific criteria relevant to disposal and use practice
[see Section 3.2.2.2 for a more detailed discussion of applicable limits].
Thus, POTVs applying sludges to cropland or composting for example, must
develop local limits to avoid violations of applicable State and Federal
sludge disposal limitations (see definition of interference, Section 1.3.1).
Vhen IU discharges render sludge unsuitable for land application and
necessitate landfilling, incineration, or additional treatment of sludges, the
POTV not only must pay the costs of additional treatment, but may lose the
revenue obtained from selling sludge. This is considered interference.
POTVs that normally dispose of sludge through landfilling or incineration
may also be adversely affected by certain IU discharges and should develop
local limits that assure their method of sludge disposal will not be restrict-
ed. POTVs that practice sludge incineration may be regulated by air quali ty
standards (see Section 2.1.6). Sludges and residual ashes resulting from the
incineration of sludges, destined for landfills should be tested for EP
toxicity (see Section 3.2.2.3). As discussed in Section 3.2.2.3, exceeding EP
toxicity concentrations may result in the need to dispose of the residuals in
a hazardous waste landfill. The costs of disposal in such landfills greatly
exceeds that of disposal in solid waste landfills.
2.1.4 Operational Problems
Receipt of some industrial wastes may interfere with POTV operations,
resulting in a violation of NPDES permit conditions calling for specific
removal efficiencies to be achieved and for the plant to be well-operated and
maintained. Moreover, some discharges of pollutants, while not causing POTV
NPDES permit violations or violations of sludge disposal regulations, can
nevertheless disrupt POTV operations, increase POTV operation and maintenance
2-3
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costs, and may cause violations of specific prohibitions. For example, IU
discharges that inhibit the POTV's biological treatment systems result in
reduced POTV efficiency and, as a result, increased operating costs. At
worst, process inhibition may necessitate reseeding and stabilization of the
treatment unit. In addition, process inhibition or upset may result in the
production of sludges that require either special treatment before disposal,
or disposal in a manner not generally practiced by the POTV. This would be
considered interference.
POTVs may need to develop local limits to resolve these problems.
Section 3.2.2.1 discusses procedures POTVs can follow in setting local limits
based on biological process inhibition data. Chapter 4 discusses ways to
avoid O&M problems in collection systems through local limits.
2.1.5 Vorker Health and Safety
Flammable/explosive and/or fume toxic pollutants discharged to POTVs can
pose a threat to the health and safety of POTV workers. Local limits can be
used to regulate the discharge of flammable/explosive and/or fume toxic pollu-
tants. POTV workers may be susceptible to the inhalation of toxic gases that
form or accumulate in collection systems. The vapors of volatile organic
compounds (VOCs) are of major concern since they may be both toxic and carcin-
ogenic, and may produce both acute and chronic health effects ov«r various
periods of exposure.. Also of concern are the hazards associated with the
toxic gases produced when certain inorganic discharges mix in the collection
system. Acidic discharges, when combined with certain nonvolatile substances
such as sulfide and cyanide, can produce toxic gases/vapors that are hazardous
to humans (e.g., hydrogen sulfide and hydrogen cyanide gases).
In response to the potential hazards to human health associated with
toxic vapors, POTVs may establish local limits based on the maximum recom-
mended VOC levels in air. Section 4.2 provides guidance for developing local
limits based on worker health and safety concerns as they relate to the
accumulation of toxic gases.
Explosion and fire hazards comprise an additional health and safety
concern for POTV workers. Accumulation of volatile substances in the treat-
ment works can produce an influent that ignites or explodes under the proper
2-4
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conditions, potentially injuring POTV workers. Oxygen-activated sludge tanks
and confined headvorks are examples of areas of concern for fire and explosion
hazards in treatment plants. Fire and explosion hazards are regulated under
the specific prohibitions of 40 CFR 403.5(b). Development of local limits for
those pollutants which pose fire or explosion hazards to POTVs is discussed in
Section 4.1.1.
2.1.6 Air Emissions
The General Pretreatment Regulations do not require the adoption of local
limits to protect air quality unless there are air quality standards associ-
ated with the POTV's sludge use or disposal practice. However, POTVs may
choose to adopt local limits for this purpose, or may be required to do so by
the State.
Emissions from sewage sludge management and disposal activities may be
regulated under three separate regulatory programs under the Clean Air Act.
The first two programs involve Federal standards that limit emissions from
sewage sludge incinerators regardless of their location. The third Federal
program is comprised of National Ambient Air Quality Standards (NAAQS), and
State air pollution control regulations that are imposed on emissions in order
to attain NAAQS. These regulations vary from State to State, and according to
local air quality conditions. States and localities may also have their own
air quality regulations and control requirements in addition to those
associated with the Federal rule. Each of the three regulatory programs is
discussed in more detail below.
The first rule is the New Source Performance Standard (NSPS) for particu-
late emissions from sewage sludge incinerators under Section 111 of the Clean
Air Act. This standard (40 CFR 60, Subpart 0) requires that incinerators
constructed after June 11, 1973 emit no more than 0.65 grams of particulates
per kilogram of dry sludge input, or 1.30 lb/ton of dry sludge input. In
addition, the regulation prohibits the discharge of gases that exhibit 20
percent opacity or greater. EPA is now considering revisions to the standard
that would leave the emission limits unchanged, but require additional
monitoring and recordkeeping, and more thorough compliance tests. The purpose
2-5
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of the revisions is to help ensure proper operation and maintenance of the
incinerator, thereby reducing air emissions through more complete combustion.
As the Section 111 NSPS limitations for particulate matter are not
pollutant-specific, and compliance with these limitations is dependent on
proper POTV sludge incinerator operations rather than on industrial user
pollutant discharge limitations, local limits cannot be based on Section 111
NSPS limitations.
The second set of regulations consists of the two National Emission
Standards for Hazardous Air Pollutants (NESHAP) under Section 112 of the Clean
Air Act. These two standards limit particulate beryllium and total* mercury
emissions from sewage sludge incinerators. If the incinerator was constructed
or modified after June 11, 1973, the incinerator must also comply with the
NSPS particulate matter limitations as just described. The requirements of
all of these air quality standards apply independently. The standard for
beryllium (40 CFR 61, Subpart C) limits particulate beryllium emissions from
all sewage sludge incinerators to 10 grams over a 24-hour period.
Alternatively, the plant operators may choose to comply with an ambient
concentration limit of 0.01 ug/m3 averaged over a 30-day period. The NESHAP
for mercury (40 CFR 61, Subpart E) limits total mercury emissions to 3200
grams per 24-hour period.**
The standards under Sections 111 and 112 just described apply regardless
of the incinerator's location. Under the third Clean Water Act program,
regulatory requirements may vary from State to State, and from location to
location within a State. Section 109 of the Clean Air Act directs EPA to set
National Ambient Air Quality Standards (NAAQS) that apply to the entire
nation. Section 110 provides for the States to develop State Implementation
Plans (SIPs) that contain regulatory requirements for specific sources
designed to achieve and maintain compliance with EPA's ambient standards
(NAAQS).
* The mercury standard applies to emissions of "mercury in particulates,
vapors, aerosols, and compounds" [40 CFR 61.51(a)].
~~Compliance with this limitation is determined by analyzing sludge for total
mercury, as per analytical procedures detailed in 40 CFR 61, Appendix B,
Method 105.
2-6
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On July 1, 1987, EPA promulgated a final regulation that set a new NAAQS
for particulate matter. This particulate matter standard (52 FR 24634-24750,
July 1, 1987) applies to particles with an aerodynamic diameter of less than
10 microns, referred to here as PM1(). The primary NAAQS for PM10 consist of
an expected annual arithmetic mean of 50 micrograms per cubic meter (ug/m3)
with no more than one expected exceedance per year. The primary NAAQS are set
at a level necessary to protect human health. The secondary NAAQS for PM1()
are an annual geometric mean of 60 ug/m3 and a maximum 24-hour concentration
of 150 ug/m3 not to be exceeded more than once a year. Secondary NAAQS are
set at a level necessary to prevent welfare effects of air pollution (e.g.,
materials or crop damage). As EPA and the States implement the new PM1(J
standards, and identify the attainment status of communities, additional
control requirements may be established.
Another applicable ambient standard which is perhaps more relevant to the
POTV's local limits development program is NAAQS for particulate lead. The
particulate lead NAAQS (40 CFR 50, §50.12) is a maximum arithmetric mean of
1.5 micrograms per cubic meter averaged over a calendar quarter.
The State or local regulations that are imposed on sources of particulate
matter and particulate lead emissions vary from State to State based on
regional air quality conditions and the nature and number of air pollution
sources. The regulations that may be imposed on a P0TV include additional
restrictions on particulate or particulate lead emissions from sewage sludge
incinerators, controls on fugitive emissions from sewage sludge piles, or
emissions associated with handling of sludge, including the operation of heavy
equipment and the particulate emissions that they may cause. The plant
owner/operator should contact both the local air quality agency (if one
exists) and the State air pollution control agency to determine the source-
specific control requirements that may apply to a given P0TV. These may
include State/local requirements that are not related to Federal regulatory
programs. If State or local lead air quality regulations apply to a P0TV, the
P0TV is required to assess the need for lead local, limits which will ensure
compliance with these air quality regulations.
2-7
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EPA is also examining POTVs as a source of VOC emissions, and may develop
a Control Techniques Guidance (CTG) document for use by the States in con-
trolling industrial discharges of VOC-containing wastewaters to public sewer
systems. Volatilization may occur from the sewer system, or at the treatment
plant itself. The largest amount of VOC emissions occur at POTVs that have a
large number of industrial users that discharge VOC bearing wastewaters to the
public sewer system, although some volatilization probably occurs at all
plants because of consumer use of solvents and other products, and sewer
discharges from small businesses such as machine shops and gasoline stations.
As with particulate matter, VOC emissions are of regulatory concern both
because of their contribution to ambient concentrations of a pollutant regu-
lated by an NAAQS (i.e., ozone), and the toxicity of individual compounds. No
Federal air quality regulations now exist that control VOC emissions from
POTVs. EPA has not developed an NSPS for air emissions from POTVs, nor has
EPA developed a hazardous air pollutant standard. EPA has assessed emissions
of seven toxic organics and VOC emissions from POTVs (51). EPA plans to
continue to assess, and possibly require, some industrial categories to reduce
the VOC content of their sewer discharges. These requirements may in turn
lead to future requirements for POTVs to establish local limits on VOC
discharges.
The NAAQS for ozone (40 CFR 50, §50.9) is currently 0.12 parts per
million or 235 ug/m3. Many metropolitan areas across the country have not yet
attained the ambient standard, and EPA and the States are trying to achieve
additional VOC emission reductions. As more pressure is applied to reduce VOC
emissions and thereby reduce ozone concentrations, regulatory authorities may
begin to emphasize regulation of wastewater treatment facilities. Such
regulation, in turn, would likely be the driving force for establishing
additional POTV local limits development requirements. EPA is currently
considering whether to make the ozone NAAQS more restrictive, which could have
the effect of increasing the intensity of the search for new VOC control
opportuni ties.
POTV owner/operators should contact both local and State air quality
control agencies to determine whether there are regulatory requirements that
apply to their facility.
2-8
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2.2 CHARACTERIZING INDUSTRIAL DISCHARGES
Once the POTV has identified the concerns that should be addressed by the
development of local limits, the specific pollutants of concern should be
identified. This identification procedure should begin vith an evaluation of
industrial users and their discharge characteristics. The following sections
deal vith data sources available to help characterize IU discharges and also
briefly discusses three types of IU discharges vhich may be of particular
concern to POTVs or vith vhich they may be less familiar.
2.2.1 Industrial User Discharges
POTVs cannot make informed decisions concerning potential problem
discharges in the absence of a comprehensive data base on industrial con-
tributions to their systems. There are numerous sources that a POTV can drav
on to obtain information about its industrial users and the composition and
quanitities of their discharges.
Critical to a thorough evaluation of industrial users is the performance
and maintenance of a complete industrial waste survey (IVS). The IVS is one
of the most effective methods for obtaining comprehensive information about
the users of- the POTV. All industrial users, including commercial users such
as gasoline stations and dry cleaners, should be included in the IVS. A
typical IVS may require submission of some or all of the folloving information
from each IU:
Name
Address
Standard Industrial Classification (SIC) Code
Wastewater flow
Types and concentrations of pollutants in discharge(s)
Major products manufactured and/or services rendered
Locations of discharge points
Process diagram and/or descriptions
An inventory of raw feedstocks, including periodically used solvents,
surfactants, pesticides, etc.
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Results of inspections, including documentation of spills, compliance
history, general practices
Treatment processes, and management practices such as spill prevention
plans and solvent management plans, employed
Discharge practices, such as batch versus continuous, variability in
waste constituent concentrations and types, discharges volume
Pollutant characteristics data (i.e., carcinogenicity, toxicity,
mutagenicity, neurotoxicity, volatility, explosivity, treatability,
biodegradability, bioaccumulative tendency).
The IVS should request any additional information that may be useful to
the POTV in identifying and assessing the pollutants of concern discharged, or
potentially discharged, by the IU. Complete and up-to-date data are
invaluable to POTVs in accomplishing the following:
Identifying previously unknown characteristics of an IU and its
discharges,
Evaluating the potential for slug loadings,
Planning a logical monitoring/sampling strategy that will ensure
efficient use of POTV resources, and
Estimating raw waste loadings of pollutants for which analytical
methods are unavailable.
Although most POTVs should have already conducted an IVS, the survey must be
periodically updated to be useful. Guidance on conducting an IVS is provided
in EPA's Guidance Manual for POTV Pretreatment Program Development.
IVS data may be reviewed in conjunction with the pollutant occurrence
matrices provided in Appendix C. The matrices present information on the
types of pollutants expected in the discharges from various industrial groups.
In addition to the IVS, the following sources of information will aid the
POTV in identifying pollutants of concern:
The IU's permit application
EPA Development Documents for Categorical Industries (see Appendix D).
Development documents sumarize processes employed at categorical
2-10
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industries, typical treatment technologies, and priority pollutants
detected in discharge from categorical industries. (Available from
the National Technical Information Service.)
EPA Pretreatment Guidance Manuals*. Guidance Manuals provide lists of
the priority pollutants characteristic of discharges from various
categorical industries. (See Appendix A.)
Data bases compiled by the North Carolina Department of Natural
Resources and Community Development**. These data bases consist of
reports of POTV effluent toxicity and the associated discharges of
toxics from industrial user. In addition, the data bases contain
information that chemical manufacturers have provided on the chemical
characteristics (i.e., measured toxicity) of biocidal compounds.
Michigan Critical Materials Register***. This data base, published by
the Michigan Department of Natural Resources, provides information on
pollutant properties such as toxicity, carcinogenicity, bioconcen-
tration, mutagenicity, and teratogenicity, as veil as information on
the types of pollutants used or discharged by various industries. The
data base includes both priority and nonpriority pollutants, and is
developed from actual sampling data and information supplied by
industries.
State and Regional NPDES permitting authorities. NPDES permitting
authorities maintained databases of pollutants detected in direct
discharger effluents. POTVs can review the data to identify those
pollutants that may be discharged by similar indirect dischargers.
. Industrial Users. POTWs, through a permit or ordinance mechanism, can
require Ills to provide toxicity data for pollutants detected in the
IU's wastewater. Industries can often obtain such data from the
manufacturers of raw feedstocks, solvents, surfactants, pesticides,
etc.
* Currently available manuals: "Guidance Manual for Electroplating and Metal
Finishing Pretreatment Standards," U.S. Environmental Protection Agency
Effluent Guidelines Division, Washington, D.C., February, 1984. "Guidance
Manual for Pulp, Paper, and Paperboard and Builders' Paper and Board Mils
Pretreatment Standards," U.S. Environmental Protection Agency Effluent
Guidelines Division, Washington, D.C., July, 1984. "Guidance Manual for
Iron and Steel Manufacturing Pretreatment Standards," U.S. Environmental
Protection Agency Industrial Technology Division, Washington, D.C.,
September, 1985.
** Information on this data base can be obtained from the North Carolina
Division of Environmental Management, Water Quality Section, P.O. Box
27687, Raleigh, NC 27611.
***Available from: Mr. Gray Butterfield, Michigan Department of Natural
Resources, Lansing, MI 48909.
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RCRA Form 8700-12. Facilities that generate hazardous work must
submit Form 8700-12 to the appropriate State or Regional agency (see
Appendix E). The form contains a description of waste types and
volumes generated at the facility, as well as a description of the
facility's disposal practices. The RCRA regulations that define a
hazardous waste (40 CFR Part 261) list the waste constituents that
correspond to the waste codes used on Form 8700-12 and identify
specific industrial hazardous wastes and some of their constituents.
Collection and review of existing data sources is an important intitial
step in identification of pollutants of concern. It can be used to direct
further sampling and analytical work and can identify industrial/commercial
soures that may need control.
2.2.2. RCRA Hazardous Vastes
The acceptance of Resource Conservation and Recovery Act (RCRA) defined
hazardous vastes by a POTV may require considerable resources for continued
compliance with CVA and RCRA requirements. Hazardous wastes may be legally
introduced into a POTV by one of two means either discharged to the
collection system via an industrial facility's normal sewer connection, or
transported to the POTV treatment plant (inside the treatment plant property
boundary) via truck, rail, or dedicated pipeline (TRDP).
RCRA hazardous wastes, when mixed with domestic sewage in the POTV's
collection system prior to reaching the treatment plant's property boundary,
are excluded from regulation under RCRA by the Domestic Sewage Exclusion
(DSE). The exclusion applies only after the wastes are mixed. Hazardous
wastes are still subject to RCRA until they are discharged to the POTV and
mixed with domestic sewage. As RCRA regulations become more restrictive due
to the Hazardous and Solid Vaste Amendments of 1984, there are increased
incentives for industry to take advantage of the DSE. Realizing this fact,
municipal officials should identify the industrial activities that generate
and discharge hazardous wastes so that they are able to control and manage
these wastes. Vhile exempt under RCRA, these wastes are subject to full
regulations and control under the Clean Water Act and must meet all applicable
categorical and local discharge limitations.
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Hazardous wastes may be received directly at a POTV by truck, rail, or
dedicated pipe (TRDP) only if the POTV is in compliance with RCRA requirements
for treatment, storage, and disposal facilities (TSDFs) [see 40 CFR 270.60).
The responsibilities and liabilities of POTVs accepting TRDP wastes are
explained in summary form in Appendix E, while detailed guidance is available
in EPA's Guidance Manual for the Identification of Hazardous Vastes Delivered
to POTVs by Truck, Rail or Dedicated Pipeline (February, 1987).
If POTVs are aware of hazardous waste discharges to the sewer, they
should determine which pollutants are present and at what concentrations. The
fact that a waste is a listed or characteristic hazardous waste under RCRA
provides only limited information on its chemical constituents, and none at
all on chemical concentration.
2.2.3 CERCLA Vastes
The 888 facilities on (or proposed for) the National Priority List make
up only a small portion of the almost 21,000 hazardous sites (including Fed-
eral, State and local) that will either require or are in the process of
clean-up. Of the sites that are on the National Priority List, it is esti-
mated that approximately 10 percent will ultimately truck some clean-up wastes
to sewage treatment plants.
Types and sources of wastewaters resulting from site clean-ups that may
be trucked to POTVs include: leachate from landfills, contaminated ground
water, aqueous wastes stored in containers, tanks and surface impoundments,
treatment sludges from remedial treatment at clean-up sites, and runoff from
contaminated soils. Approximately 400 different chemicals have been charac-
terized at NPL1 sites, with the 10 most common being trichloroethylene, lead,
toluene, benzene, PCBs, chloroform, tetrachloroethylene, phenol, arsenic and
cadmium. This frequency of occurrence provides no indication of the concen-
trations at which specific compounds were measured. Vhile many CERCLA wastes
are quite dilute, some sites have reported high concentration of metals and
organics (chromium at 1758 mg/1, bis(2-chloroethyl) ether at 210 mg/1 and
chloroform at 200 mg/1).
XReport to Congress on the Discharge of Hazardous Vastes to Publicly Owned
Treatment Works. USEPA, EPA/530-SU-86-004, February 1986.
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POTVs contemplating the acceptance of CERCLA clean-up wastes should
require detailed chemical analyses and treatability testing before any
decisions are made regarding actual acceptance of the waste. These data can
then be used to determine the presence of pollutants of concern (see Section
2.3).
2.2.4 Hauled Wastes
Many POTVs have historically accepted hauled septage and instituted a
charge for the waste accepted. However, in accepting hauled wastes little
consideration is generally given to the potential for industrial wastes being
discharged along with domestic sewage.
POTVs with Federally-required pretreatment programs must have adequate
legal authority to regulate their waste haulers, as 405.1(b) of the General
Pretreatment Regulation states that "This regulation applies to pollutants
from non-domestic sources covered by Pretreatment Standards which are in-
directly discharged into or transported by truck or rail or otherwise intro-
duced into POTVs ..." Also, Section 403.5 of the Pretreatment Regulations
applies Prohibited and Specific Discharge Standards "to all non-domestic
sources introducing pollutants into a POTV".
In making or reviewing the decision to accept hauled wastes, municipal
officials are confronted with a variety of options and decisions. Major
points for consideration are provided below:
Acceptance of domestic/industrial wastes
POTVs should consider accepting only domestic wastes from septage
haulers, and adjust the language on their sewer use ordinances to
reflect this. If industrial wastes are not prohibited, the inspector
must determine if categorical wastes are present and require com-
pliance with Federal Standards. If industrial wastes are accepted
from haulers, it may also be more difficult to discriminate between
illegal discharges of hazardous wastes and legal discharges of
industrial wastes. Generally, hauled hazardous wastes can be dis-
charged legally only within the treatment plant property boundary and
not to the collection system. The POTV must also meet RCRA require-
ments for a hazardous waste treatment/storage/disposal facility (see
Section 2.2.2). Thus, if hauled wastes are accepted at discharge
points in the collection system, increased documentation of the
sources of the wastes may be necessary to prevent illegal discharges.
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Discharge Site Selection
In selecting a site for accepting hauled wastes, officials should
consider:
- Site accessibility for trucks
- Availability of monitoring facilities
- Site security
- Proximity to treatment plant.
Waste Monitoring
For the POTV's regulations governing waste haulers to be taken
seriously, an enforcement process must exist. Enforcement can take
the form of random sampling at the discharge ports and checking
documentation accompanying the wastes. Random sampling frequencies
should be adjusted in accordance with the amount of industrial waste
expected.
Documentation of Hauled Wastes
Municipalities may choose to register haulers and require documenta-
tion of the source, volume, and character of each load. This docu-
mentation could be easily verified with the generator on a routine
basis.
Penalties
Since nondomestic wastes may potentially upset plant operations, it is
important that adequate penalties exist for improper disposal of
wastes, or falsification of information on the nature of the hauled
wastes. The city council should be involved in carefully considering
this issue.
Cost Recovery
Once a system of administration and monitoring is established, the
cost of implementation should be recovered through charges to the
users.
Additional information is available in EPA's Guidance Manual for the Identifi-
cation of Hazardous Wastes Delivered to POTWs by Truck, Rail, or Dedicated
Pipeline (Office of Water Enforcement and Permits, February 1987).
2.3 REVIEW OF ENVIRONMENTAL PROTECTION CRITERIA AND POLLUTANT EFFECTS DATA
Once a POTW has evaluated its industrial users and has determined the
pollutants that its IUs are reasonably expected to be discharging to the POTW,
2-15
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it should design a sampling and monitoring program which is thorough enough to
verify the actual concentration levels of pollutants expected to be discharged
in significant quantities, and broad enough to detect any problem pollutants
which were not uncovered by the industrial waste survey. Before designing the
sampling program, the POTV may want to review environmental quality criteria/
effects data for pollutants which are potentially of concern. The review of
available environmental quality criteria and effects data will help to design
an efficient sampling program.
2.3.1 Environmental Protection Criteria and Pollutant Effects Data
Criteria that can be used to identify potential pollutants of concern are
listed below. The available data for each of the following criteria are
provided for a number of pollutants in Appendix G, and Tables 3-2 through 3-5.
Criteria for Identifying Pollutants Causing Process Inhibition:
Activated sludge inhibition threshold data
Trickling filter inhibition threshold data
Anaerobic digester inhibition threshold data
Nitrification inhibition threshold data
Criterion for Identifying Chemically Reactive Pollutants:
National Fire Protection Association (NFPA) hazardous classification
Criteria for Identifying Pollutants with Potential to Endanger POTV
Worker Health and Safety!
American Conference of Governmental Industrial Hygienists (ACGIH)
Threshold Limit Value - Time Weighted Averages (TLV-TVAsJl The
maximum concentrations of contaminants in air that will not produce
adverse noncarcinogenic health effects in humans who are exposed 8
hours/day, 40 hours/week.
Criteria for Identifying Pollutants with Potential to Pass-Through and
Degrade Water Quality:
National Acute Freshwater Quality Criteria: Nonregulatory maximum
contaminant levels experimentally derived to protect aquatic life from
acute toxicity. Water quality criteria or State water quality
standards can be used as a basis for deriving local limits to prevent
instream toxicity.
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Criteria for Identifying Pollutants with the Potential to Degrade Sludge
Quality:
Pollutants Under Consideration for Municipal Sludge Regulation: Those
pollutants originally considered for regulation by EPA during the
regulatory development phase of technical sludge disposal criteria (40
CFR 503), and
Pollutants Proposed for Inclusion into the RCRA TCLP Test: Pollutants
proposed for regulation by the RCRA Toxicity Characteristic Leaching
Procedure (TCLP) described in the Federal Register (Vol. 51, No. 44,
June 13, 1986). The TCLP test is a leachate analysis test for
sludges, similar to the EP toxicity test.
2.4 MONITORING OF IU DISCHARGES, COLLECTION SYSTEM, AND TREATMENT PLANT TO
DETERMINE POLLUTANTS OF CONCERN
A memorandum issued by the EPA Office of Water Enforcement and Permits
(contained in Appendix B) stated that POTVs must use site-specific data to
identify pollutants of concern. Pollutants of concern were defined as any
pollutants which might reasonably be expected to be discharged to the POTV in
quantities which could pass through or interfere with the POTV, contaminate
the sludge, or jeopardize POTV worker health or safety. The memorandum
identified six pollutants which are potentially of concern to all POTVs
because of their widespread occurrence in POTV influents and effluents and
their possible adverse effects on POTVs. These are cadmium, chromium, copper,
lead, nickel, and zinc. In this guidance, EPA is identifying four additional
pollutants that all POTVs should presume to be of concern unless screening, of
their wastewater and sludge shows that they are not present in significant
amounts. These are arsenic, cyanide, silver, and mercury. These pollutants
are not as widespread in POTV influents as the six metals, but they have
particularly low biological process inhibition values and/or aquatic toxicity
values. In the case of cyanide, production of toxic sewer gases is also a
concern. POTVs should screen for the presence of all ten pollutants using IU
survey data as well as influent, effluent, and sludge sampling.
In addition to these ten pollutants, POTVs should consider the full range
of priority, conventional, and nonconventional pollutants (as defined by the
Clean Water Act) in identifying pollutants of concern. EPA is particularly
interested in the organic priority pollutants and the hazardous constituents
listed in RCRA Appendix 9. (See Appendix H of this manual.)
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To aid in the identification of additional pollutants of concern, the
following step by step approach is provided as guidance. The conceptual
approach is presented in Figure 2-1 - A Simplified Conceptual Flow Diagram for
Determining Pollutants of Concern.
In identifying pollutants of concern, a two pronged approach may be
adopted, based on chemical specific analyses and/or toxicity testing of
wastewaters. The chemical specific approach can be further subdivided into
concerns relevant to the collection system, and those relevant to the
treatment plant.
In branch A (Chemical Specific Approach) of the figure a suggested
approach for identifying additional pollutants of concern based on collection
system concerns is presented, as follows:
A1 - Monitoring and Screening - The POTV should monitor IU discharges and
various points within tne collection system as a preliminary
screening to detect potential problem discharges. This could entail
the use of lower explosive limit (LEL) meters, flash point testers,
sampling of volatiles in sewer headspace, pH measurement devices,
and thermometers to determine the presence of dangerous or otherwise
undesirable discharges to the sewers. Visual observations might
reveal deterioration of the sewerline or blockages.
A2 - Investigative Sampling and Analyses of Problem Discharges - Should
the results of the monitoring and screening identify specific
discharges that could cause problems within the sewer system, the
facility files should be reviewed and the discharge sampled to
confirm/determine the exact nature of the problem.
A3 - Institution of Controls - Once the problem industries/discharges are
identified, controls should be imposed upon the facility. These may
take the form of local discharge limits (see Chapter 4), form of
industrial user management practices (Chapter 5), or case-by-case
technology-based requirements on the IU (Chapter 6).
Blocks AA through A7 of the chemical specific approach provide an
abbreviated outline for identifying additional pollutants of concern based on
treatment plant concerns. (The chemical specific approach for treatment plant
concerns is quite involved and is provided in greater detail in Figure 2-2).
A4 - Sampling of Industrial Users - Conducting sampling and analyses of
discharges allows POTWs to accurately characterize each facility's
2-18
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I
A) Chemical-Specific Approach
¦
Begin Evaluation Process
I
i
B) Toxicity-Based Approach
Collection System Concerns
Plant-Related Concerns
81) Toxicity Totting of
POTW Effluent
r
82) Identification of Cause
of Effluent Toxicity
Through Fractionation
S3) Identification of
Problem Discharges
Through Batch
Reactor Tasting
'
B4) Institution of Controls
B5) Toxicity Testing to
Confirm Effectiveness
of Controls
Figure 2-1. A Simplified Conceptual Flow Diagram for Determining
Pollutants of Concern
2-19
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Is poNuianl
detected?
Is the
maximum influent
concentration mora
jhan I/500th the tludss Qutde^
line concentration/
Yes
Do the
"results of a (Mutton"1
No y/^analysia of the maximum>
influent concentration exceed
^Sute watei quality standards,,
or Federal guidance
criteria?
Is the
ammum grab samp
No ^Concentration moie than on^v No
half, or a the maximum 24-hour
composite concentration
njnore than one touilhu
the inhibition
JhresholdL
Stop
)
Proceed With Detailed
Headwords li>ading Analysis
Figure 2-2. Detailed
Concern
Flow Sheet for a Chemical-Specific Approach to Identifying Pollutants of
to Treatment Plant Operations
-------
discharge and confirm the industrial vaste survey data. This is
especially important where a discharge makes up a large percent of
the total industrial pollutant loading to the system, or when
pollutants of concern are known or suspected to be discharged in
large quantities or concentrations. This data allows for more
accurate evaluation of potential impacts on the POTV and allows for
greater confidence in any resulting limits.
A5 - Monitoring/Screening of POTV Influent/Effluent/Sludge - The POTV
should perform a limited amount of influent, effluent, and sludge
sampling to determine what pollutants are detectable and in what
concentrations. It should include priority pollutants and any
pollutants that might reasonably be expected to be present based on
the IVS. Pollutants with GC/MS peaks greater than 10 times the
adjacent background should be identified.
A6 - Comparison of Pollutant Concentrations with Criteria Levels - The
measured pollutant concentrations should be compared with reference
levels based on applicable sludge criteria/guidelines, water quality
criteria/standards, and plant process inhibition thresholds (see
Figure 2-2 for details on reference levels).
A 7 - Sampling of Plant Influent/Effluent/Sludge to Determine the Maximum
Allowable Pollutant Headworks Loadings - For those pollutants that
are at levels greater than the reference levels, an analysis to
determine allowable pollutant loading to the plant headworks should
be conducted (see Chapter 3).
A8 - Institute Controls - The allowable loading to the treatment plant
should be allocated to the POTV's users and the resulting local
discharge limits (and monitoring requirements) enforced.
Branch B of the flow diagram presents a toxicity based approach to
identifying additional pollutants of concern.
B1 - Toxicity Testing of the POTV Effluent - Toxicity testing of the POTV
effluent may be a NPDES permit requirement. (See Section 2.6.)
B2 - Identification of the Cause of Toxicity Through Fractionation -
Should the testing undertaken in Bl reveal that the effluent is
toxic, fractionation of the effluent wastewater and subsequent
toxicity testing may identify the type of compound responsible for
the observed toxicity.
B3 - Identification of Problem Discharges Through Treatability Testing of
Industrial Discharges - Use of batch reactors to perform treat-
ability testing of industrial effluents, with toxicity testing
before and after the simulated treatment, will help to identify
discharges responsible for toxicity in the POTV effluent. (See
Section 2.6 below.)
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B4 - Institution of Controls - Upon identification of the discharges
responsible for the toxicity, controls imposed upon the facility
might include discharge limitations or industrial user management
practices.
B5 - Toxicity Testing to Confirm the Effectiveness of Controls - Once the
source of controls have been instituted by the IU, toxicity testing
at the POTV should be performed to confirm the effectiveness of
control measures.
As mentioned above, the use of a chemical specific approach to determin-
ing pollutants of concern related to treatment plant operations can be an in-
volved process. Figure 2-2 is a detailed flow sheet of one possible approach.
This approach is based primarily on analysis of the POTV's influent, with
limited effluent and sludge sampling to screen for pollutants which may not be
detectable in the influent but which may have concentrated in the effluent or
sludge. The flow sheet provides a series of reference levels which POTVs may
use in assessing influent wastewater data and determining the need to proceed
with a headworks analysis. These reference levels, provided as guidance for
each of the protection criteria, are intended to be conservative in order to
account for the daily fluctuations in pollutant loadings experienced by POTVs
and for the fact that the decisions are usually made based on limited data.
The reason for emphasizing the use of influent data in this example approach
with only limited effluent and sludge data being used, is to conserve re-
sources during the preliminary screening and allow more resources to be used
for the detailed headworks analysis of particular pollutants. The need to
proceed with a headworks analysis for particular pollutants is indicated when:
The maximum concentration of the pollutant in the POTV's effluent is
more than one half the allowable effluent concentration required to
meet water quality criteria/standards or the maximum sludge concentra-
tion is more than one half the applicable sludge criteria guidelines;
or
The maximum concentration of the pollutant in a grab sample from the
POTV's influent is more than half the inhibition threshold; or the
maximum concentration of the pollutant in a 24-hour composite sample
from the POTV's influent is more than one fourth the inhibition
threshold.
The maximum concentration of the pollutant in the POTV's influent is
more than l/500th of the applicable sludge use criteria. (The use of
a "1/500" reference level is suggested based on a review of POTV data
(Fate of Priority Pollutants in Publicly Owned Treatment Works -
2-22
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EPA/440/1-82/303) indicating that a 500 fold concentration of pollu-
tants can occur in digested sevage sludges as compared to the waste-
water influent to the treatment plant); or
The concentration of the pollutant in the plant influent exceeds water
quality criteria adjusted through a simple dilution analysis.
Decisions as to whether to conduct a detailed headworks loading analysis
are represented by the diamonds in Figure 2-2. If a pollutant level exceeds
the reference levels, then the POTV should conduct a detailed headworks
loading analysis for that pollutant to assess whether a local limit need be
established. The headworks loading analysis should be based on comprehensive
influent, effluent, and sludge sampling, as discussed in the next section.
2.5 MONITORING TO DETERMINE ALLOWABLE HEADWORKS LOADINGS
Having presented methods for identifying pollutants of concern, this
section presents guidance on the types of sampling that should be conducted in
order to perform a headworks loading evaluation for those pollutants and
derive numeric local limits. While many POTWs derive limits based on reported
literature values for such things as pollutant removal efficiencies, industry
wastestream and domestic sewage characteristics, it is always preferable for a
POTW to utilize actual data. For ease of discussion, three sections are
presented: (1) monitoring locations, (2) monitoring frequencies, and
(3) sample type, duration and timing.
2.5.1 Sampling Locations at the Treatment Plant
Sampling at the treatment plant will provide data on existing pollutant
loadings, removal efficiences across the various processes, and quantities of
pollutants partitioning to the sludge and in the plant effluent.
Locations that should be sampled at the treatment plant are listed below.
Following the list is a discussion concerning the reasons for sampling at
these locations.
Raw sewage influent to the treatment plant
Effluent from treatment plant
Effluent from primary treatment (or influent to secondary treatment)
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Effluent from secondary treatment (or influent to tertiary treatment)
Vaste activated sludge
Influent to sludge digester
Sludge disposal point.
Treatment plant influent and effluent sampling would be conducted to
obtain loading data for use in calculating overall POTV removal efficiencies.
POTV influent sampling should be conducted at the headworks prior to combina-
tion with any recirculation flows.
Primary treatment effluent monitoring should be conducted to obtain
requisite loading data for calculation of pollutant removal efficiencies
across primary treatment. Removal efficiencies across primary treatment are
used in local limits calculations to convert secondary treatment (e.g.,
activated sludge) biological process inhibition data into corresponding
headvorks loadings. Similarly, for POTVs equipped with tertiary treatment
units, secondary treatment effluent monitoring should be conducted to obtain
requisite loading data for calculation of pollutant removal efficiencies
across secondary treatment. These removal efficiencies are used in local
limits calculations to convert tertiary treatment (e.g., nitrification)
biological process inhibition data into corresponding headworks loadings.
For those pollutants for which State/Federal sludge disposal criteria/
standards and/or sludge digester inhibition threshold data are available/
applicable, the POTV should monitor its sludge at two distinct points: at the
influent to the sludge digesters and at the point of disposal of the processed
sludge. The resulting sludge monitoring data are used to derive digester
removal efficiencies and sludge partitioning constants necessary for conver-
sion of sludge disposal criteria/standards and digester inhibition threshold
data into corresponding headworks loadings.
2.5.2 Establishing Monitoring Frequencies
Once the POTW has identified all monitoring locations, it must decide on
appropriate monitoring frequencies for sampling. An initial sampling program
should be designed to collect all data necessary to derive the limits. Once
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local limits have been established, an ongoing monitoring program should be
set up to enable the POTV to periodically re-evaluate the limits. An empiri-
cal, case-by-case approach to setting monitoring frequencies is recommended.
As a guide, EPA suggests that the initial monitoring program should include at
least five consecutive days of sampling for both metals and toxic organics to
adequately characterize the wastewater in a minimal time frame. Suggested
guidelines for ongoing monitoring are for at least one day of sampling per
month for metals and other inorganics, and one day of sampling per year for
toxic organics (these include the organic priority pollutants, and depending
on the Ills present, may also include organics on RCRA's Appendix 9; see
Appendix H of this manual), to assess long-term variations in wastewater
composition. These recommended sampling frequencies may be modified based on
the following site-specific factors:
The variability in pollutant loads in wastewaters
The types and concentrations/loadings of pollutants
Seasonal variations in wastewater flows and/or pollutant loadings.
The POTW should consider each of these factors when establishing approp-
riate monitoring frequencies. Each factor is discussed below.
When establishing monitoring frequencies, the POTV should account for the
variability of pollutant levels in the wastewaters. If a wastewater to be
sampled is known to be highly variable in composition, the POTW should monitor
that wastewater more frequently in order to catch peak pollutant levels. The
information available to EPA on toxic pollutant concentrations in municipal
sewage indicates that, as a general rule, considerable .day to day variability
occurs. Often, the daily maximum concentration of a composite sample is
several times the monthly average. Therefore, monitoring on five consecutive
days is recommended for the initial sampling program. As an example of the
variability in pollutant loadings to a POTW, Figure 2-3 is a graph depicting
the wide swings in toluene loadings experienced by Chattanooga, TN. IU
discharges may vary over the course of a day as various process operations
occur. As such, it is useful for field personnel to have a good knowledge of
IU operations before establishing the sampling regime.
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600
580
560
540
520
500
480
460
440
420
400
FIGURE 2-3. TOLUENE LOADING TO THE CHATTANOOGA
TENNESSEE POTW
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Two additional considerations in establishing the required monitoring
frequency are the types and concentrations/loadings of pollutants in the
wastewaters. Information on types and amounts of pollutants expected to be
present in the plant influent will be obtained from the preliminary IU survey
and sampling data. If a thorough preliminary evaluation indicates that
certain toxic pollutants are not expected to be present in the plant influent
at detectable levels, then a limited amount of sampling to confirm this would
be sufficient. It is strongly recommended, however, that even POTVs that have
few known industrial contributors of toxic pollutants carry out several days
of sampling for metals and cyanide and perform more than one influent scan for
toxic organics using a gas chromatograph (GC) or a gas chromatograph/mass
spectrometer (GC/MS). This is necessary because there may well be unexpected
sources of toxics, such as waste haulers, illegal connections, commercial
users, cooling water discharges, etc.
POTVs should assess seasonal and other long term variations in its
wastewater composition. If seasonal variation is expected to be very signifi-
cant, the POTV should attempt to address this variation in the initial
monitoring program prior to developing local limits. Situations where
seasonal variability might be important include cases where major IUs operate
seasonally (e.g., canneries) or where combined sewer overflows during wet
weather increase the influent loadings of certain pollutants.
An additional consideration in establishing monitoring frequencies is the
availability and reliability of resources (i.e., funding, equipment, person-
nel). The capability and capacity of the POTVs analytical laboratory is
particularly critical in assessing available resources and in determining
whether to utilize outside commercial analytical services. The POTV should
not neglect to consider the impact on the laboratory when establishing a
monitoring program in support of local limits development. An adequate
initial monitoring program is essential to developing appropriate local
limits, even though it may cause additional resource demands for a limited
time.
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2.5.3 Establishing Sample Type, Duration, and Timing of Sample Collection
In this section, a brief discussion on establishing sample type, sampling
duration, and timing of sample collection is provided. More detailed guidance
on these topics can be found in the following references:
NPDES Compliance Sampling Inspection Manual (PB81-153215)
Code of Federal Regulations (40 CFR Part 136)
Handbook for Sampling and Sample Preservation of Vater and Wastewater
(EPA 600/4-82-029).
To ensure valid data, representative measurements of flow rates must be
taken at the point and time of sample collection. Flow measurements and
sampling can be conducted either manually or with automatic devices. Com-
posite samples should be used by the POTV for most of the sampling conducted
for local limits development, particularly in the calculation of removal
efficiencies. However, grab samples should be used for pollutants that may
undergo chemical/physical transformations (e.g., cyanide, phenol and vola-
tiles) and samples of batch discharges from industrial users, and samples used
to detect slug loadings.
Composite samples should be taken over a 24-hour period. For those
pollutants which might be expected to undergo chemical/physical transformation
during the compositing period, such as cyanide, phenols, and volatile organ-
ics, EPA recommends collection of one grab sample every 3 to 4 hours with
compositing in the laboratory prior to analysis. EPA recommends the use of
composites for the following reasons:
Receiving stream water quality criteria/standards are based on the
highest instream concentration of a toxic pollutant to which aquatic
organisms can be exposed for a given duration. Effluent limits based
on these criteria are normally developed using a 1-day or 7-day
average stream flow and the annual average effluent flow. They are
expressed as daily maximum and monthly average concentration limits.
In order to meaningfully compare POTV effluent concentrations to these
limits, 24-hour composite sampling, rather than grab sampling, of the
POTW effluent should be conducted.
Owing to the nonsteady state conditions within the POTW, it is
virtually impossible to calculate a representative removal efficiency
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based on influent/effluent grab samples timed exactly to the POTV's
current actual (not design) hydraulic retention time; the effects of
nonsteady state conditions on POTV removal efficiencies are dampened
out over time through compositing yielding a more representative
average removal efficiency.
If a shorter composite sampling duration (e.g., 8 hours) is specified in
the POTV's NPDES permit, this shorter sampling duration may be more appro-
priate for POTV influent/effluent monitoring than the 24-hour composite
sampling duration recommended above.
For industrial user sampling, the length of the composite sample should
be timed to the facility's operating hours. If an industrial user operates
one 8-hour shift and discharges only during these hours, then sampling needs
to be conducted only during these hours. However, if the facility operates
longer hours or discharges after hours (such as for cleanup), then longer
sampling times are necessary.
2.6 TOXICITY TESTING
In the past few years, EPA has placed increased emphasis on controlling
ambient toxicity in receiving waters. This emphasis was formalized in the
policy statement published in 49 FR 9105 (Policy for the Development of Water
Quality-based Permit Limitations for Toxic Pollutants) which described a
technical approach for assessing and controlling the discharge of toxic
substances to the Nation's waters through the NPDES permit program.
The goal of the program is to control toxic pollutants with an integrated
approach consisting of both chemical-specific and biological methods. In
order to achieve this goal, EPA will enforce existing specific numerical
criteria for toxic pollutants and will use biological techniques and available
data to assess toxicity impacts and human health risks.
The Clean Water Act (as amended by the Water Quality Act of 1987) in
Section 303(c)(2)(B) requires States to develop standards for all chemicals
for which EPA has developed Water Quality Criteria (Section 308(a)(1)). It
also requires that:
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Where such numerical criteria (for toxic pollutants) are not
available, whenever a State reviews water quality standards
pursuant to paragraph (1), or revises or adopts new standards
pursuant to this paragraph, each State shall adopt criteria
based on biological monitoring or assessment methods consistent
with information published pursuant to section 304(a)(8).
In the next few years, increasing pressure will arise to control toxic
pollutants whether or not they have been incorporated into State standards.
The narrative standards that all delegated States have, requiring no discharge
of toxics in toxic amounts, provide sufficient legal basis for controlling
specific chemicals and/or whole effluent toxicity as appropriate.
Even if there are no identifiable chemicals of concern in a POTV dis-
charge, it is desirable to test effluents for toxicity. The principal
advantage of toxicity testing of an effluent is that the test is able to
detect and measure the overall toxicity of a complex mixture. Where toxicity
is found, steps can be taken to correct the problem either through the
identification of causitive toxicants, or through changes in the influent or
treatment process itself. Testing can be done by a number of laboratories at
reasonable cost using protocols developed by EPA (Methods for Measuring the
Acute Toxicity of Effluents to Marine and Freshwater Organisms,
EPA/600/4-85-013, and Short-term Methods for Estimating the Chronic Toxicity
of Effluents and Receiving Waters to Freshwater Organisms, EPA/600/4-85-014).
If results of these toxicity tests indicate that an effluent is not toxic,
then no further action is necessary. If the effluent is toxic, the methods
outlined in the Technical Support Document for Water Quality-Based Toxics
Control (September 1985) can be used to determine whether effluent toxicity
will exceed the national criteria for instream toxicity. If instream toxicity
is greater than these criteria, several steps may be taken to decide whether
local limits for toxicity would be appropriate.
2.6.1 Toxicity Reduction Evaluations (TREs)
A toxic POTW effluent can be caused by one or more of several thousand
toxic chemicals. This wide range of chemicals presents a practical challenge
to determining which of these chemicals might be causing toxicity. For this
reason, techniques have been developed that simplify the approach to determin-
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ing the cause of toxicity. Formal approaches to these techniques are called
toxicity reduction evaluations, or TREs.
The purpose of a TRE is to determine the constituents of the POTV
effluent that are causing toxicity, and/or to determine the effectiveness of
pollution control actions such as local limits or POTV process modifications
to reduce the effluent toxicity [52]. Figure 2-4 provides a conceptual flow
diagram for performing a TRE at a POTV.
Efforts are currently underway by the U.S. EPA Vater Engineering Research
Laboratory to develop, test, and refine protocols for conducting TREs at both
industrial plants and municipal wastewater treatment facilities. The Environ-
mental Research Laboratory in Duluth, Minnesota is researching methods for
fractionating wastewaters. In addition, various TREs and TRE development
efforts are being carried out by characterizing sources of toxicity in
effluents by both industries and contract organization [52). Because of the
variety of research efforts being undertaken by a number of organizations, EPA
is still in the process of developing TRE guidance and methods. Therefore
this discussion does not present specific protocols, but explains the concept
upon which TREs are based. Even though research is still underway, toxicity
has beeri successfully reduced by a number of POTVs. Successful implementation
has usually occurred when expert knowledge of industrial waste characteristics
has been coupled with detailed analysis of POTV effluent characteristics.
Toxicity Identification Evaluations
Toxicity identification.evaluation (TIE) is one component of a TRE. The
process involves sequential treatment or fractionation and analysis of the
constituents of the POTV effluent. In this fractionation, the effluent is
split into a number of parts. The effluent remaining after removal of each
part is tested for toxicity. Hopefully, the removal of one part will reduce
toxicity much more than the others, and this part removed can either be
further fractionated and tested for toxicity or chemically analyzed to
determine potentially toxic chemicals. Vhen the chemicals are identified,
likely generators of these chemicals are identified, and their discharges can
be analyzed for either the presence of the chemical, toxicity, or both. If an
industry is discharging the chemical and has a toxic discharge, then local
limits can be applied as discussed in Chapter 4 of this guidance.
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Figure 2-4. Example Approach for a Municipal TRE
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Many approaches exist for conducting TIEs. One typical approach entails
the following treatments:
Air strippingthe effluent remaining after air stripping is tested
for toxicity. If toxicity is reduced, volatiles have caused toxicity.
Complexationa chelating agent is added to the effluent to bind
metals in a nontoxic form. If toxicity is reduced in the effluent,
metals are probably the cause of the toxicity.
Acid extractionbase/neutral organic compounds are removed by acid
extraction. Toxicity reduction in the effluent indicates the causa-
tive toxic agent which is in this fraction.
Resin column strippingorganics are removed from the whole effluent
by passing it through a resin exchange column. Chemicals can be
stripped from the column in fractions, using serial concentrations of
a relatively non-toxic solvent (e.g., methanol). Further chemical
analysis is then used to identify toxic constituents in a toxic
fraction, if toxicity is found in this effluent fraction.
This series of steps indicates whether toxicants are likely to be inorganic,
volatile, organics, or oxidants.
If none of these treatments results in reduced toxicity of the effluent,
more inventive approaches must be taken. Usually, however, one or more
fractions contain the primary cause of the toxicity, and chemical analyses of
that fraction identify the causative agents.
Confirmatory toxicity tests can then be conducted on the isolated
compounds to verify that they constitute the toxic agents and that other,
unidentified compounds are not contributing substantially to toxicity. Vith
these confirmatory tests, a logical, technically defensible argument is
developed that is a strong basis for developing local limits.
However, the general methodology has certain limitations. It has been
found at some POTVs that the cause of toxicity varies from day to day,
complicating the determination of toxic constituents. Toxicity has also been
caused by chemicals in more than one fraction of the effluent, reducing the
benefits of the fractionation procedure. Variability of an IU's discharge
may mean that apparent toxicity reduction (or elevation) over time is simply
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due to variations in concentration of toxicants. Satisfactorily confirming
the sources of toxicity in a municipal wastewater effluent will require
development of approaches which can recognize factors such as the influence of
variability in the source of the toxicity, the slug loading of toxics to the
treatment plant, and the relationship of influent toxicity to final effluent
toxicity, especially considering the role of biodegradability of compounds
through the wastewater treatment system. EPA is currently developing guidance
that addresses many of these factors. [53]
Batch Treatability Testing of Industrial Discharges
In general, toxic discharges will contribute to the toxicity of the
effluent. However, two apparently anomalous situations can develop. Some-
times an apparently non-toxic discharge can contribute to POTV effluent
toxicity. This apparent anomaly arises because some toxic chemicals (for
example, metals) may be "bound" to other chemicals and are not toxic in the
bound form, but are "released" to solution during treatment. The opposite
situation can also arise, where a toxic IU discharge can be greatly reduced in
toxicity through biodegradation, volatilization, or settling of toxic con-
stituents in the POTV.
Acknowledging these limitations, POTVs with relatively few industrial
dischargers can apply toxicity testing to dischargers suspected of being a
source of toxic compounds to determine if any, or all, of the discharges may
be toxic.
When a specific industrial/commercial facility is suspected of dis-
charging pollutants causing toxicity the POTV needs to determine whether the
toxicants are passing through the treatment plant to contribute to plant
effluent toxicity. This can be accomplished through the batch treatment
testing of discharges. A variety of approaches to batch treatability testing
exist. In general, these include the simulation of the treatment plant
operational characteristics (F/M ratio, MLVSS) in reactors, and utilizing
varying concentrations of the IU's discharge as the reactor feed. Measurement
of the substrate utilization rates in the various reactors, and subsequent
testing of the settled supernatants for toxicity, provide information on the
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relative wastewater strength (and hence pollutant concentration) at which
toxicity may occur, and whether pass through of the toxicity to the receiving
stream should be a concern. This information may provide the basis for limits
development.
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3. LOCAL LIMITS DEVELOPMENT BY THE ALLOWABLE HEADVORKS LOADING METHOD
In this chapter, the headworks loading allocation method of deriving
local limits is discussed in detail. This method addresses treatment plant,
water quality, and sludge impacts only and does not apply to collection system
impacts. Chapters 4, 5, and 6 of this manual discuss other methods for the
development of local limits, including collection system effects/concerns.
3.1 GENERAL METHODOLOGY
This method allows local limits to be developed based on criteria
pertaining to POTV wastewater treatment plant operations and performance, the
quality of the POTW's sludge, and the water quality of the POTV's receiving
stream. The derivation of these local limits is a two-step procedure,
outlined below:
Step 1: Development of Maximum Allowable Headworks Loadings
Site specific treatment plant/environmental criteria pertaining to
pollutant pass through, process inhibition/interference, and sludge
quality are identified. The criteria used in local limits development
include POTV NPDES permit limits, receiving stream water quality
standards/criteria, biological process threshold inhibition levels, and
sludge quality criteria.
A mass balance (input=output) approach is then used to convert criteria
into allowable headworks loadings. This approach traces the routes of
each pollutant through the treatment process, taking into account
pollutant removals in upstream units. Steady state calculations for
conservative pollutants (e.g., total metals) assume that the influent
loading to a treatment process equals the sum of the effluent and sludge
loadings out of that process. In the case of nonconservative pollutants
(e.g., volatile organics, cyanide, dissolved metals), where, biodegrada-
tion/volatilization and chemical degradation are significant,
calculations are modified to take these losses into account.
For each pollutant, the smallest (i.e., the most stringent) of the
allowable headworks loadings derived from the above-listed criteria is
selected as the pollutant's maximum allowable headworks loading. If the
POTV's actual headworks loading is consistently below this maximum
allowable loading, compliance with all applicable criteria for the
particular pollutant is ensured.
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Section 3.2 discusses the development of maximum allowable headworks
loadings in detail. Owing to the importance of removal efficiencies in
deriving maximum allowable headworks loadings, Section 3.2 concludes
(Section 3.2.4) with a discussion of representative removal efficiencies
and how they can be derived.
Step 2: Allocation of Maximum Allowable Headworks Loadings
Once maximum allowable headworks loadings have been derived (in Step 1),
a portion of this loading (for each pollutant) is subtracted as a safety
measure to account for projected industrial loading increases,
unanticipated slug loadings, and errors in measurement. Pollutant
loadings from domestic/background sources are then subtracted from the
allowable headworks loadings. The results of these calculations are the
maximum allowable industrial loadings to be allocated to the POTV's
industrial users. Local limits are derived from this allocation of
allowable industrial loadings.
Section 3.3 discusses procedures for setting safety factors and for
allocating maximum allowable headworks loadings to domestic/background
and industrial sources. Section 3.3.1 discusses the application of
safety factors and Section 3.3.2 discusses the determination of domestic/
background pollutant loadings. Finally, Section 3.3.3 details four
methods for allocating allowable industrial loadings to industrial users,
thereby establishing local limits.
Appendix I presents a comprehensive local limits derivation example,
demonstrating this methodology and related calculation techniques.
3.2 DEVELOPMENT OF MAXIMUM ALLOWABLE HEADWORKS LOADINGS
The first "step in deriving local limits is to develop maximum allowable
headworks loadings based on treatment plant/environmental criteria. These
criteria can be classified as either pass through or interference criteria, as
follows (see Section 1.3.1 for regulatory definitions of pass through and
interference)*
Pass through criteria
- NPDES permit limits
- Water quality standards/criteria
Interference criteria
- Biological treatment process inhibition data
Sludge disposal standards/guidelines
- EP toxicity limitations
Sludge incinerator air emission standards
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Section 3.2.1 discusses the development of allowable headworks loadings based
on the above-listed pass through criteria, and Section 3.2.2 details the
development of allowable headworks loadings based on the interference
criteria. Section 3.2.3 discusses the comparisons of allowable headworks
loadings for each pollutant to determine the most stringent loading. The most
stringent loading for each pollutant constitutes the pollutant's maximum
allowable headworks loading, from which a local limit can be derived.
Section 3.2.4 discusses the derivation of representative removal efficiencies,
which are parameters critical to the calculation of allowable headworks
loadings.
3.2.1 Allowable Headworks Loadings Based on Prevention of Pollutant Pass
Through
Procedures are provided in this section for the derivation of allowable
headworks loadings from treatment plant/environmental criteria pertaining to
pollutant pass through. Pollutant pass through has been previously defined in
Section 1.3.1 of this manual.
3.2.1.1 Compliance with NPDES Permit Limits
NPDES permit limits are to be used in the-derivation of local limits to
prevent pollutant pass through. The following equation is used to convert a
pollutant-specific concentration-based NPDES permit limit into the cor-
responding allowable headworks loading of that pollutant.
(8.34)(Ccrit)(QP0TW)
d-RpoTw)
Where:
Lin = Allowable influent loading, lbs/d
CCRIT = NPDES permit limit, mg/1
Qpotw = POTV flow, MGD
Rp0TW = Removal efficiency across POTV, as a decimal
Occasionally, the POTW's NPDES permit specifies whole effluent toxicity
limits in conjunction with pollutant-specific concentration-based discharge
limits. Effluent toxicity considerations in developing local limits are
discussed in Section 2.6.
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The POTV's NPDES permit may include a narrative provision requiring POTV
compliance with State water quality standards and/or toxicity prohibitions.
POTVs possessing NPDES permits with this narrative provision should contact
the appropriate State environmental agency to determine their specific
responsibilities in deriving water quality-based local limits. These POTVs
should inquire as to exactly which State water quality standards or toxicity
testing requirements apply to their receiving streams at the points of
discharge. The following subsection of this manual provides general guidance
on deriving local limits from water quality standards/criteria.
3.2.1.2 Compliance with Water Quality Limits
Water quality limitations for the POTV's receiving stream comprise
another local limits development basis.
The following equation is used to derive allowable POTV headworks
loadings from water quality standards or criteria.
T ^STR + QpOTW^ ~ ^STR ^STR^
" d-Rpotw)
Where:
LI(J = Allowable influent loading, lbs/d
Ccrit = Vater quality standard, mg/1
Qstr = Receiving stream (upstream) flow, MGD
QD= POTV flow, MGD
POTW '
C'str = Receiving stream background level, mg/1
Rpoxw = Removal efficiency across POTV, as a decimal
The above equation derives an allowable receiving stream pollutant
loading based on a water quality standard and then allocates this entire
loading to the POTV. The equation does not allow for allocations to other
dischargers within the POTV's stream reach. For this reason, the validity of
the above equation should be discussed with State environmental agency
personnel prior to deriving water quality-based allowable headworks loadings.
The State agency may require alternative procedures for derivation of water
quality-based allowable headworks loadings.
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Two principal sets of water quality limitations have been developed:
Individual State water quality standards
EPA ambient water quality criteria.
State water quality standards have been developed by various State
environmental agencies as maximum allowable pollutant levels in State water
bodies. These State agencies conduct wasteload allocation studies based on
their State water quality standards, and then set limits for direct dis-
chargers based on the results of these studies. State water quality standards
can depend on hardness of the water and the stream reach classification. The
POTV should contact the State to obtain the specific water quality standards
for the POTV's receiving stream at the point of discharge.
In lieu of State water quality standards, local limits also can be based
on EPA ambient water quality criteria. These criteria do not possess the same
regulatory basis as State water quality standards; they are merely EPA's
recommended maximum contaminant levels for protection of aquatic life in
receiving streams. Nevertheless, EPA ambient water quality criteria may
provide a sound basis for a POTV in developing local limits for pollutants
which have the potential of causing toxicity problems in the receiving stream.
A POTV may choose to rely on such local limits as a central component in a
control strategy to meet the "no discharge of toxics in toxic amounts"
narrative requirements in its permits. This is particularly the case where
the POTV needs to establish local limits for toxicants shown to be causing
effluent toxicity (through a TRE) and thus preventing the POTV from complying
with its toxicity-based permit limit.
Relevant EPA water quality criteria are classified as follows:
Protection of freshwater aquatic life
Protection of saltwater aquatic life
Protection of human health.*
* Usually application of human health criteria requires that the State make
certain judgments about risk and exposure which are rather site-specific.
Vhile EPA may need to take action where a State fails to do so, the
application of human health criteria generally is beyond the scope of this
document. For further information, the POTV may consult its State or EPA
permitting authority.
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The criteria for protection of freshwater and saltwater aquatic life
consist of chronic and acute toxicity criteria. These criteria are presented
in Table 3-1 [from Quality Criteria for Water, 1986 ("The Gold Book"), EPA
440/5-86-001, EPA Office of Water Regulations and Standards, Washington, DC,
May 1986 (Reference 25 in this manual's reference list)J. Several of the
criteria for protection of freshwater aquatic life are hardness dependent.
For these pollutants, the levels given in Table 3-1 represent criteria at an
assumed hardness of 100 mg/1 as CaC03.*
When calculating allowable headworks loadings based on protection of
freshwater and saltwater aquatic life, both chronic and acute toxicity
criteria should be used if they exist. The chronic toxicity criteria are
designed to protect aquatic organisms against long term effects over the
organism's lifetime, as well as across generations of organisms. Acute
toxicity criteria are generally designed to protect aquatic organisms against
short term lethality.
Chronic criteria should not be used to develop a monthly average local
limit, nor should acute criteria be used to develop a daily maximum limit, as
is sometimes thought. The following procedure may be followed to develop
local limits based-on acute and chronic water quality criteria for aquatic
life. This procedure is adopted from the EPA guide, Permit Writer's Guide to
Water Quality-based Permitting for Toxic Pollutants [63].
For calculating an allowable headworks loading based on a chronic
toxicity criterion, the receiving stream flow rate (QSTB) used in the
calculations should be the lowest 7-day average for a 10-year period
(referred to as 7Q10). For calculating the corresponding allowable
headworks loading based on an acute toxicity criterion, the receiving
stream flow rate should be the single lowest one-day flow rate over a
10-year period (1Q10). For each pollutant, the two allowable head-
works loadings should be compared (i.e., the loading based on a
chronic criterion and the 7Q10 flow vs. the loading based on an acute
criterion and the 1Q10 flow) and the smaller loading retained as more
stringent [63].
* Criteria for certain inorganic pollutants (e.g., ammonia) are pH and/or
temperature dependent as well. Criteria for these pollutants have not been
not presented in Table 3-1.
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The most stringent loading should then be used to derive the daily
maximum limitation using the equation on p. 3-4 of this manual. If
the POTV wishes to also adopt a monthly average limit, then the
simplest approach is to use a "rule of thumb" such as dividing the
daily maximum by a factor between one and two, a practice sometimes
used by NPDES permit writers. A more technically correct but fairly
detailed approach is described in the Permit Writer's Guide, pages
17-21 [63].
Note that it is not correct to say that daily maximum limits are based
on protecting against acute toxicity and monthly average limits are
based upon protecting against chronic toxicity (63]. The limits
derivation process calculates local limits based on the more stringent
of the two allowable headvorks loadings.
The POTV should check with the appropriate State environmental agency to
see if State-specific guidelines exist regarding alternative stream flows to
use. For POTWs discharging to the ocean, saltwater dilution techniques for
oceans are described in the Revised Section 301(h) Technical Support Document
[64] and the 301(h) publication entitled Initial Mixing Characteristics of
Municipal Ocean Discharges [65]. For POTVs with other unique flow situations
(e.g., multiple flows, estuaries, etc.), the Technical Support Document and
the Permit Writer's Guide should be consulted for guidance.
It should be noted that the allowable headworks loading equation
presented on p. '3-4 of this manual requires upstream background pollutant
levels for the POTV's receiving stream. Reliable, updated sources of such
water quality data may be difficult to find. Also, pollutant level fluctua-
tions in many receiving streams tend to diminish the validity of water quality
monitoring data. For guidance on the requisite receiving stream background
concentration data to use in local limits calculations, the appropriate State
environmental agency should be consulted.
In order to use receiving stream water quality limitations in deriving
local limits, the POTV should refer to the equation and procedures outlined
above. For each pollutant, the lowest of the maximum allowable headworks
loadings based on all of the above criteria should be used when setting local
limits.
3-7
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3.2.2 Allowable Headworks Loadings Based on Prevention of Interference with
POTV Operations
In this section of the manual, procedures will be presented for deriving
allowable headworks loadings from POTV treatment plant process inhibition/
interference criteria.
The equations presented in this section are based upon generic configura-
tions of major POTV treatment units. The presence and configuration of
internal POTW wastestreams, such as sludge digester or gravity thickener
supernatant recycle streams, were not considered in the derivation of these
equations. The POTV is urged to verify the validity of the equations (and the
representativeness of plant sampling locations used for data collection)
before attempting to use these equations in deriving local limits.
3.2.2.1 Prevention of Process Inhibition
An appropriate POTW process inhibition/interference criterion measures
the capability of the POTV's biological treatment systems to accommodate
pollutants and still adequately remove BOD. Threshold inhibition levels
provide a measure of this capability of biological treatment systems to
accommodate pollutants without adverse effects, and hence provide a sound
basis from which to establish local limits.
The following equations are used to derive allowable headworks loadings
from secondary and tertiary treatment threshold inhibition levels:
Secondary treatment (e.g., activated sludge) L
threshold inhibition level
IN
(8.34)(CCRIT)(Qp0TW
Tertiary treatment (e.g., nitrification) L
threshold inhibition level
(8.3A)(cCRIT)(Q
POTW
Where:
Lin = Allowable headworks loading, lbs/d
CCRit = Threshold inhibition level, mg/1
= P0TV flow» MGD
POTW '
RpRiM = Removal efficiency across primary treatment, as a decimal
Rsec = Removal efficiency across primary and secondary treatment,
as decimal
3-8
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The RpRIM and RSEC reflect cumulative removal efficiencies through primary and
secondary treatment, respectively.
In order to derive local limits that prevent anaerobic digester inhibi-
tion/interference, the following mass balance equations can be used to convert
anaerobic digester threshold inhibition levels into allowable headworks
loadings:
For Conservative Pollutants (Metals):
Sludge digester LI(J = =r
threshold inhibition level potw
For Nonconservative Pollutants (Organics/Cyanide):
Sludge digester LJN = L X L"" 1
threshold inhibition level diq
Vhere:
Lin = Allowable headworks loading, lbs/d
CCRIT = Threshold inhibition level, mg/1
Qdig = Sludge flow to. digester, MGD
Rpotw = Removal efficiency across POTW, as a decimal
Ljnf = POTV influent pollutant loading, lbs/d
CDI(J = Pollutant level in sludge to digester, mg/1
A distinction is drawn in the above equations between a conservative
pollutants (not degraded within the POTV or volatilized) such as metals, and
nonconservative pollutants such as organics/cyanide. This distinction is
necessary because organics/cyanide can be removed by volatilization and
biodegradation, as well as through sludge adsorption, whereas the removal of
metals is by sludge adsorption alone. Losses through biodegradation and
volatilization do not contribute to pollutant loadings in sludge, and the
presumption applied to metals, that removed pollutants are transferred
entirely to sludge, is not valid for organic pollutants or for cyanide. As
can be seen from the above equations, one result of this distinction between
conservative and nonconservative pollutants is that sludge monitoring data
(i.e., C0 data) are required to derive the nonconservative pollutant
allowable headworks loadings, whereas removal efficiency data are required to
derive the conservative pollutant allowable headworks loadings.
3-9
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Literature data pertaining to pollutant inhibition of the following
biological treatment systems are provided in this section:
Activated sludge units
Trickling filters
Nitrification units
Anaerobic sludge digesters.
In general, it is easier to use total metal, rather than dissolved metal,
inhibition levels in deriving local limits based on biological treatment
process inhibition. This is because:
POTV removal efficiency data used in local limits calculations pertain
to the removals of total, rather than dissolved metals
Allowable headworks loadings derived on other bases, such as NPDES
permit limits, water quality standards, etc., are generally based on
treatment plant/environmental criteria expressed as total, rather than
dissolved, metal.
Table 3-2 presents literature data on activated sludge inhibition for
metals, nonmetal inorganics, and organics. As can be seen from Table 3-2,
inhibition data are often presented in the literature both as ranges and as
single inhibition levels. Without additional site-specific information
regarding POTV performance in accommodating these pollutants, the Minimum
Reported Inhibition Thresholds presented in Table 3-2 should be used in
deriving local limits.
The literature provides minimal inhibition data for trickling filter
units. Table 3-3 presents available literature inhibition data for trivalent
chromium and cyanide in trickling filters. More extensive literature data are
available pertaining to inhibition of nitrification. Table 3-4 documents
nitrification threshold inhibition data for various metals, nonmetal
inorganics, and organics.
Table 3-5 presents inhibition threshold data for anaerobic sludge
digesters. The inhibition threshold data presented in Table 3-5 are based on
total rather than dissolved pollutant, unless otherwise noted. For reasons
mentioned above, inhibition levels for total pollutant are preferable for use
in deriving local limits.
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3.2.2.2 Protection of Sludge Quality
One of the principal motivations for establishing local limits is to
prevent restriction of the POTV's sludge disposal options. EPA and State
agencies have established limitations on the land application of sludge. The
following equations can be used to convert these limits i-nto allowable
headworks loadings.
Conservative Pollutants (Metals):
, . . , <8-3*>
Sludge Disposal Criterion LJN = =
POTW
Nonconservative Pollutants (Organics/Cyanide):
Sludge Disposal Criterion LJM = LIHp X I ^LCR1Tj
^ s LOO
Vhere:
Ljn = Allowable influent loading, lbs/d
Cslcrit = Sludge disposal criterion, mg/kg dry sludge
PS = Percent solids of sludge to disposal
QSLDg = Sludge flow, to disposal, MGD
RpoTw 3 Reraoval efficiency across POTW, as a decimal
LINr = POTW influent pollutant loading, lbs/d
CstDG = Pollutant level in sludge to disposal, mg/kg dry sludge
As with the derivation of organic pollutant allowable headworks loadings
from anaerobic digester inhibition data (see Section 3.2.2.1), the distinction
is drawn between conservative pollutants, which are neither degraded nor vola-
tilized within the POTW, and nonconservative pollutants. As noted in Section
3.2.2.1, the rationale for drawing this distinction is that losses due to
degradation and volatilization do not contribute to pollutant loadings in the
sludge. It should be noted from the above equations that sludge monitoring
data (i.e., CSLD(J data) are required to derive the allowable headworks load-
ings for nonconservative pollutants, whereas removal efficiency data are
required to derive the allowable headworks loadings for conservative pollu-
tants.
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Table 3-6 presents Federal and selected State sludge disposal limitations
for metals and organics in land-applied sludge. The table illustrates that
some State sludge disposal limitations have the force of State regulation
behind them, others are merely guidelines for land application of sludge.
POTVs should be sure to base their local limits on regulations/guidelines
provided for their own State only. Other States' sludge disposal limitations
are not applicable. Updated and considerably more detailed tables presenting
State sludge management practices and limitations will be available soon in a
manual to be published by EPA titled "Guidance for Writing Interim Case-by-
Case Permit Requirements for Sludge" [U.S. EPA Office of Water, Permits
Division, 1987, Draft].
Table 3-6 presents three different sludge limitations for each pollutant:
Pollutant concentration limit in sludge, mg/kg dry sludge
Pollutant application rate limit on an annual basis, lbs/acre/year
Cumulative pollutant application rate limit, lbs/acre over the site
Thus, up to three different starting points may be available from which
to derive allowable headworks loadings. For each pollutant the lowest (i.e.,
most stringent) criterion is to be used in the headvorks loading calculations.
In order to compare the three types of sludge limitations presented in Table
3-6, the three limitations must be expressed in consistent units. The most
logical choice of units is milligrams pollutant per kilogram of dry sludge, as
these units are required by the headworks loading equations presented above.
Table 3-6 shows that the pollutant limits in sludge already are expressed in
these units; only the annual and cumulative application rate limits need to be
The following equations can be used to convert these two application rate
limits to milligram per kilogram sludge limits:
life.
converted.
C
LIHIA)
(AAR)(SA) mg/kg dry sludge
(Qsldg)(PS/100)(3046)
C
(CAR)(SA)
mg/kg dry sludge
lim(C) - (SL)(Qsldq)(PS/100)(3046)
3-12
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where:
C a Sludge disposal limit based on annual application rate limit,
mg/kg dry sludge
Clim(C) 3 Sludge disposal limit based on cumulative application rate
limit, mg/kg dry sludge
AAR 3 Annual application rate limit, lbs/acre/year
CAR 3 Cumulative application rate limit, lbs/acre over the site life
SA = Site area, acres
SL = Site life, years
Qetn/. = Sludge flow to disposal, MGD
S LDQ
PS = Percent solids of sludge to disposal (as a percent, not as a
decimal)
3046 = Unit conversion factor
For each pollutant, the two sludge disposal limits calculated from the
above equations should be compared with the appropriate pollutant limit in
sludge from the fourth column of Table 3-6. The lowest limit should be
selected as most stringent.
All POTVs which land apply sludge must use the Federal sludge disposal
limitations for cadmium presented in Table 3-6, if these limitations are more
stringent than State limitations for cadmium. The POTV should also contact
the State environmental agency directly to obtain a copy of the State's sludge
disposal regulations/guidelines.
The POTV should also keep abreast of the current status of Federal EPA
sludge disposal regulatory activities. In this regard, the EPA is currently
considering the development of sludge disposal regulations for a variety of
pollutants. These pollutants are presented in Column 4 of Table G-3, in
Appendix G.
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3.2.2.3 EP Toxicity Limitations
The EP toxicity test determines if a solid vaste is hazardous under the
Resource Conservation and Recovery Act (RCRA). Sludge disposed by a POTV must
not exceed the EP toxicity test limitations or it must be disposed as a
hazardous vaste in accordance with RCRA.
The EP toxicity test (40 CFR 261, Appendix II provides a detailed
description of test procedures) entails the extraction of pollutants from
sludge through the addition of a dilute acid. Table 3-7 presents analytical
limits that must not be exceeded if the sludge is to be classified as non-
hazardous.
While POTVs will generally not have sewage sludge that fails the EP
toxicity test, the costs and liabilities associated vith the management and
disposal of a hazardous sludge are such that it is in a municipality's best
interest to test their sludge, and closely monitor any trends reflected in the
test results. Significant changes may be brought about with changes in the
industrial community, or changes in the treatment plant operations.
POTVs should routinely monitor sludge metals levels (mg/dry kg) and the
corresponding EP toxicity levels to determine: (1) whether their sludge
leachate from the EP toxicity test is approaching regulatory levels; and
(2) the relationship between sludge metals concentration, and measured
leachate metals concentation (not necessarily a linear relationship). Based
on its monitoring data the POTW can then determine the dry weight metals
concentration that would be protective against EP toxic sludge, and use this
in equations presented in Section 3.2.2.2 to derive allowable headworks
loadings.
Although most POTVs would not normally be expected to generate hazardous
sludges, the EP toxicity testing requirements should be of special note to
POTVs using aerated lagoons, since lagoon sludge is often contaminated with
3-14
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exceptionally high levels of metals. EPA is presently evaluating the Toxicity
Characteristic Leaching Procedure (TCLP) as a replacement of the EP toxicity
test. The TCLP test includes 38 additional organic constituents; these
pollutants are listed in Column 5, Table G-3 of Appendix G. EPA recently
tested six municipal sludges to determine if they would be hazardous under the
proposed TCLP test. The results shoved that while none of the six tested
sludges would exceed the proposed TCLP limits, two sludges approached failure
for chloroform and benzene. In light of this study, EPA is currently continu-
ing to evaluate the proposed TCLP test.
3.2.2.4 Reduction of Incinerator Emissions
As discussed in Section 2.1.6, POTVs with sludge incinerators must ensure
that incinerator air emissions comply with NESHAP limits for particulate
beryllium and total* mercury, as well as the NAAQS limit for particulate lead
(the numeric limits for these pollutants are specified in Section 2.1.6). In
accordance with the regulatory definition of interference (See Section 1.3.1),
these POTVs are further required to prohibit through local limits pollutant
discharges in amounts sufficient to cause incinerator emissions to violate
Clean Air Act standards such as these NESHAP and NAAQS limits. In this
section, the development of maximum allowable headworks loadings based on
incinerator emission standards such as NESHAP and NAAQS limits is discussed.
As guidance in deriving maximum allowable headworks loadings based on
sludge incinerator air emissions for lead, mercury, or beryllium (or for any
pollutant not destroyed by incineration, e.g., total metals) the following
equation is provided:
LIN = o x 0.0022046 lbs/g
INC POTW
* The mercury standard applies to emissions of "mercury in particulates,
vapors, aerosols, and compounds" (40 CFR 61.51(a)).
3-15
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Where: LIN = Allowable headworks loading, lbs/day
Lstd = Emission standard, g/day
CgTD = Emission standard, ug/m3
Q1nc = Incinerator emission rate, m3/day
^inc = Incinerator removal efficiency, as a fraction:
Loading in input sludge - loading in output ash
loading in input sludge
Rpotw 3 Removal efficiency across POTV, as a fraction:
loading in POTW influent - loading in POTW effluent
loading in POTW influent
These steady state equations assume that metals in sludge fed to an
incinerator are either emitted to the atmosphere or remain behind in inciner-
ator sludge ash. For pollutants regulated on a particulate basis (e.g., lead,
beryllium), these equations further assume that metal emissions from the
sludge incinerator entirely consist of particulate (i.e., regulated) metal.
3.2.3 Comparison of Allowable Headvorks Loadings
The result of the calculations described in Sections 3.2.1 and 3.2.2
will be a number of allowable headvorks loadings for each pollutant, each
allowable headworks loading having been derived from an applicable criterion
or standard. For each pollutant, these allowable headworks loadings should be
compared, and the smallest loading for each pollutant should be selected as
most stringent. If the POTV's actual headworks loading of a particular
pollutant is consistently belov this loading, compliance vith all applicable
criteria for the particular pollutant will be ensured. This loading is
designated the "maximum allowable headworks loading" for the particular
pollutant. It is the maximum allowable headworks loading for each pollutant
which is allocated to domestic/background and industrial sources (and to which
a safety factor is applied), thereby deriving local limits. Allocation of
maximum allowable headworks loadings is discussed in detail in Section 3.3.
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3.2.4 Representative Removal Efficiency Data
It is evident from the allowable headworks loading equations presented in
Sections 3.2.1 and 3.2.2 that the derivation of representative removal effi-
ciencies, for both the entire wastewater treatment plant and across each level
of treatment or process, is a critical aspect of local limits development.
Decisions must be made concerning data manipulation, to ensure that derived
removal efficiencies reflect representative treatment plant performance. In
this section, recommended procedures for the derivation of representative
removal efficiencies are discussed.
The removal efficiency across a wastewater treatment plant, or a specific
treatment unit within the treatment plant, is defined as the fraction (or
percent) of the influent pollutant loading which is removed from the waste-
stream. The general equation for the instantaneous removal efficiency is:
zrr
fL - L
1ST EPF
INT
(100)
where: REFF = Removal efficiency, percent
^inf = Influent pollutant loading, lbs/d
Leff = Effluent pollutant loading, lbs/d
However, for purposes of calculating local limits, instantaneous removal
efficiency should not be used, but rather a representative removal efficiency
such as a mean value or a value that is achieved at least a certain percentage
of the time.. This is because instantaneous, or even daily, removal efficien-
cies are highly variable. They are affected by both wastewater character-
istics (e.g., influent load) and by factors influencing performance (ambient
temperature, operational variables, etc.). The development of a representa-
tive removal efficiency data base requires numerous influent/effluent monitor-
ing events. EPA recommends that typical removal efficiencies be based on at
least 1 year of monitoring data to account for variability. If one year of
data are not available, however, EPA recommends 5 consecutive days of monitor-
ing data as a minimum. Once the data set has been obtained, a single removal
efficiency representative of the entire data set needs to be derived for use
3-17
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in local limits calculations. Several methods exist by which this single
removal efficiency can be derived; two methods will be described in the
following subsections. Both methods involve the use of influent/effluent
loading data as opposed to concentration data. This is recommended because of
flow reduction that can occur in the treatment plant and, secondly, because
seasonal changes in flow can be quite significant.
3.2.4.1 Representative Removal Efficiencies Based on Mean Influent/Effluent
Data
A single removal efficiency can be calculated from the mean influent and
mean effluent values using the following equation.
R.ff - ^-E-5 <10°)
where: R#ff = Removal efficiency, percent
I = Mean influent loading, lbs/d
E = Mean effluent loading, lbs/d
The main disadvantage to the removal efficiency based on influent and effluent
means is that it is not apparent how often the derived removal efficiency was
achieved. However, this disadvantage can be circumvented by the alternative
approach of selecting representative removal efficiencies corresponding to
specific deciles.
3.2.4.2 Representative Removal Efficiencies Based on Deciles
A decile is similar to a data set median. A median divides an ordered
data set into two equal parts; half of the data set values are less than the
median and half of the data set values exceed the median. Deciles are simi-
lar, except that they divide an ordered data set into ten equal parts. Thus,
ten percent of the data set values are less than the first decile, twenty
percent of the data set values are less than the second decile, and so on.
The fifth decile is equivalent to the data set median.
3-18
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In order to demonstrate the derivation of removal efficiency deciles, the
following hypothetical monthly removal efficiency data will be assumed
(already sorted from smallest to greatest):
R1
=
10%
R2
=
22%
R3
=
27%
R4
=
37%
R5
=
45%
R6
s
62%
R7
=
67%
R8
=
87%
R9
=
89%
R10
=
91%
R11
=
92%
R12
=
94%
Deciles consist of the nine (N+l)/10th values of a sorted data set.
Thus, if the removal efficiency data set consists of 12 monthly
removal efficiencies, every (12+1)/10 = 1.3rd removal efficiency is
sought.
The first decile is the 1.3rd removal efficiency in the above list.
This removal efficiency lies three-tenths of the distance between the
first (10%) and second (22%) removal efficiencies in the above list.
Thus,
First decile = Dx = 10 + (0.3) (22 - 10) = 13.6%-
The second decile is the 2 x 1.3 = 2.6th removal efficiency in the
above list. The second decile lies six-tenths of the distance between
the second (22%) and third (27%) removal efficiencies in the above
list:
Second decile = D2 = 22 + (0.6) (27 - 22) = 25%
The third decile is the 3 x 1.3 = 3.9th removal efficiency in the
above list. The third decile lies nine-tenths of the distance between
the third (27%) and fourth (37%) removal efficiencies in the above
list:
Third decile = D3 = 27 + (0.9) (37 - 27) = 36%
In this same manner, all nine deciles can be derived:
Di
13.6%
25%
D3
36%
°4
48.4%
3-19
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64.52 (median)
83*
87.2%
91.42
93.42
This distribution (not a normal distribution) is illustrated in Figure 3-1.
The hypothetical POTV described by the above performance data achieved a
median removal efficiency of 64.5 percent. For much of the year, however, the
POTV achieved considerably poorer removals; for instance, the POTV achieved
less than 30 percent removal for three entire months. POTV personnel might be
concerned that local limits based on the median removal efficiency of 64.5
percent may not protect the POTV from interference/pass-through during these
three months. In such a situation, the POTV might consider selecting a
particular decile in lieu of the data set median, as more demonstrative of a
"worst-case" scenario of POTV performance.
For example, the POTV may choose to derive local limits from pass-through
criteria using the removal efficiency corresponding to the second decile (25
percent), basing this decision on the fact that the historical data show that
the POTV achieves poorer removals only 20 percent of the time. The resultant
allowable headworks loading would be about 50 percent more stringent than if
the median removal efficiency had been used.
Similarly, the hypothetical POTV may wish to derive local limits from
sludge quality criteria. In this event, the POTV should select a removal
efficiency corresponding to a decile higher than the median. For example, the
eighth decile (91.4 percent) might be selected. The resulting headworks
loading would then be about 30 percent more stringent then if the median
removal efficiency had been used.
3.2.4.3 Potential Problems in Calculating Removal Efficiencies
In attempting to analyze POTV influent, effluent, and sludge monitoring
data for the purpose of deriving removal efficiencies, the POTV may have to
resolve various data inconsistencies/anomalies, including:
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FIGURE 3-1. EXAMPLE DISTRIBUTION PLOT OF REMOVAL EFFICIEHCY DATA
3-21
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Influent, effluent, and/or sludge levels are below analytical
detection
Effluent pollutant levels exceed influent pollutant levels
The pollutant is detected in erriuent and/or sludge but is not
detected in influent.
As an actual example of these anomalous conditions, Table 3-9 documents the
results of ten consecutive days of nickel monitoring at the Chattanooga,
Tennessee Wastewater Treatment Plant [from Fate of Priority Pollutants in
Publicly Owned Treatment Works - 30 Day Study EPA 440/1-82/302]. It can be
seen from Table 3-8 that for only four of the ten days influent, effluent, and
sludge levels of nickel simultaneously exceeded the analytical detection
limit, permitting direct calculation of removal efficiencies. For three days,
the effluent levels of nickel were below analytical detection and the corre-
sponding influent levels were above detection. For two days, the influent
levels of nickel were below detection and the corresponding effluent levels
were above detection. On one day, both influent and effluent levels of nickel
were below detection.
The Chattanooga POTW data highlight two data analysis issues to be
resolved: .(1) selection of surrogate values to replace pollutant levels
reported as below detection, and (2) interpretation of negative removal
efficiencies. In deriving removal efficiencies from the Table 3-8 data, the
POTW may elect to substitute a surrogate for influent and effluent levels
reported as below detection. Three surrogates are commonly used for this
purpose: the detection limit itself; zero; and one half of the detection
limit. Selection of a surrogate equal to the detection limit constitutes the
assumption of a pollutant level which is always higher than the actual value.
Conversely, selection of a surrogate equal to zero constitutes the assumption
of a pollutant level which is always lower than the actual value. Selection
of a surrogate equal to one half of the detection limit is an attempt to
improve data set accuracy by establishing a compromise between these two
extremes.
The following guidance is provided on the selection of surrogate values
and the subsequent derivation of removal efficiencies:
3-22
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o When only a few data values are reported near or below the detection
limit, a surrogate should be substituted and all available data used
in the derivation of representative removal efficiencies.
When the majority of data values are reported at or near the detection
limit, the data set should not be used to derive representative
removal efficiencies. This recommendation is made because the
resultant representative removal efficiencies derived from such data
will be greatly influenced by the choice of the surrogate value.
Alternatives that can be used if the pollutant is of concern, even
though its concentrations are near or below the detection level,
include sampling to check for the occurrence of additional higher
concentrations, performance of spiked pilot studies, or use of repre-
sentative data from the literature.
In addition to Chattanooga POTV influent and effluent monitoring data,
Table 3-9 also presents POTV sludge monitoring data for nickel. For conserva-
tive pollutants such as nickel, sludge monitoring data can be used in deriving
POTV removal efficiences, by means of the following equation:
^SLDG ^SLDO ^SLDG
Reff - <100> - <100>
L Q C
inr imp inr
where: = Removal efficiency, percent
Lsldg = P°Hutant loading in sludge to disposal, lbs/d
Lxt(p = POTV influent pollutant loading, lbs/d
Qsldg = Sludge flow to disposal, MGD
Qimp = P0TW i°fluent flow, MGD
CSL0G = Pollutant level in sludge to disposal, mg/1
CINr = POTV influent pollutant level, mg/1
By basing conservative pollutant removal efficiencies on sludge monitoring
data, the above equation allows the POTV to circumvent the need for establish-
ing surrogate values for POTV influent and effluent levels reported as below
detection. The above equation does not apply to nonconservative pollutants,
such as organics and cyanide.
The second data analysis issue highlighted by the Chattanooga POTV data
(Table 3-9) concerns the interpretation of negative removal efficiencies.
Negative removal efficiencies are in part attributable to the fact that POTWs
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do not actually operate at steady state. Deviation from steady state opera-
tion is brought about by a number of factors including:
Variability in- POTV influent concentrations
Variability in POTV treatment performance
Accumulation of pollutants in POTV sludge
Variability in POTV effluent concentrations, due to the effect of
concentrated recycle streams within the POTV (e.g., recycled digester
supernatant)
Incidental generation of pollutants by POTV operations, such as the
generation of chlorinated organics (e.g., chloroform) as a result of
disinfection by chlorination.
It should be emphasized that the above factors can contribute to the actual
occurrence of short term negative removal efficiencies across the POTV, and
that such negative removal efficiencies should not be dismissed as uncharac-
teristic of the POTV's operating condition at any given time. The following
guidance is provided regarding negative removal efficiencies:
If removal efficiencies vary greatly from sampling to sampling, the
decile approach (see Section 3.2.4.2) to removal efficiency derivation
should be used. Negative removal efficiencies should be excluded from
this type of data analysis.
If removal efficiencies are fairly consistent from sampling to
sampling, the mean influent/mean effluent approach (see Section
3.2.4.1) to removal efficiency derivation should be used. Influent/
effluent data indicating negative removal efficiencies can and should
be included in this type of analysis.
The above guidance concerning negative removal efficiencies, as veil as
guidance concerning data surrogates presented earlier in this section, should
be reviewed by the POTV and judiciously applied as warranted on a case-by-case
basis.
3.2.4.4 Literature Removal Efficiency Data
As removal efficiencies are largely based on site-specific conditions,
such as climate, POTV operation and maintenance, sevage characteristics, etc.,
3-24
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removal efficiencies are not readily generalized for inclusion in this type of
guidance manual. To derive truly representative removal efficiencies, a
site-specific monitoring data base is required. Section 2.5 provides details
for establishing such a data base. The removal efficiencies presented in this
section are not an accurate substitute for site-specific removal efficiencies
obtained through POTV in-plant monitoring programs.
Table 3-9 presents typical primary removal efficiencies for metals,
nonmetal inorganics, and priority pollutant organics. These data were
obtained from the document Fate of Priority Pollutants in Publicly Owned
Treatment Works, commonly referred to as the 40 POTV Study. The study
involved sampling and analysis of influent, effluent, sludge, and internal
wastestreams of 40 representative wastewater treatment plants. The table
presents the median removal efficiencies for primary treatment units, derived
as part of the 40 POTV Study. Representative primary removal efficiencies are
necessary for calculating maximum allowable headyorks loadings based on
secondary treatment threshold inhibition levels (see Section 3.2.2.1).
Tables 3-10 and 3-11 present removal efficiency data for metals, nonmetal
inorganics, and priority pollutant organics in activated sludge and trickling
filter treatment plants, respectively. The data are based on an analysis of
removal efficiency data presented in the 40 POTV Study. The tables provide
second and eighth decile removal efficiencies, as well as median removal
efficiencies, for the listed pollutants. The definition and use of removal
efficiency deciles have been detailed in Section 3.2.4.2 above. Representative
secondary removal efficiencies are necessary for calculating maximum allowable
headworks loadings based on NPDES permit limits, water quality standards/
criteria, sludge digester inhibition data, and sludge disposal standards/
criteria for secondary treatment plants, as well as tertiary treatment
inhibition data for tertiary treatment plants (see Sections 3.2.1 and 3.2.2).
Table 3-12 presents second decile, eighth decile, and median removal
efficiencies for metals, nonmetal inorganics, and priority pollutant organics
in tertiary treatment plants. Again, the data are based on an analysis of
removal efficiency data presented in the 40 POTV Study. Tertiary removal
efficiencies are used in calculating maximum allowable headworks loadings
3-25
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based on NPDES permit limits, water quality standards/criteria, sludge
digester inhibition data, and sludge disposal standards/criteria for tertiary
treatment plants (see Sections 3.2.1 and 3.2.2).
The removal efficiency data presented in Tables 3-9 to 3-12 are intended
as supplementary guidance to removal efficiency data and documentation
provided elsewhere (e.g., the PRELIM program, EPA's Guidance Manual for
Pretreatment Program Development, etc.). As noted previously, literature
removal efficiency data should only be used when site-specific removal
efficiencies obtained from POTW in-plant monitoring programs cannot be
obtained.
3.3 PROCEDURE FOR ALLOCATING MAXIMUM ALLOWABLE HEADWORKS LOADINGS
In this, the second step of local limits development, maximum allowable
headworks loadings, derived as detailed in Section 3.2 above, are converted
into local limits. A portion of the maximum allowable headworks loading for
each pollutant is allocated to:
Safety factor
Domestic sources
Industrial sources.
Allowable headworks loading allocations can be carried out by following a
number of procedures. The selection of an appropriate allocation procedure
for a specific POTW should be an integral aspect of that POTW's local limits
planning and decision-making process. The POTW may select any allocation
method, so long as the selected method results in a system of local limits
that is enforceable and that meets minimum objectives (prevention of pass-
through, interference, compliance with specific prohibitions and other State
and local requirements). When choosing an allocation method, the POTW may
wish to consider: (1) how easily the derived local limits can be implemented
and enforced, and (2) the relative compliance burdens the derived local limits
will impose on each IU. The POTW may also wish to consider whether to incorp-
orate a safety factor to hold part of the allowable pollutant loadings in
reserve for future growth or to compensate for possible slug loadings.
3-26
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Finally, POTVs may need to take a hard look at "domestic" sources of pollu-
tants, to see if any might actually be better classified as nondomestic
sources with reducible pollutant loadings. This practice is recommended for
those POTVs for which background loading allocations use up nearly all of the
allowable loadings of some pollutants.
In this section of the manual, local limits issues and POTV options in
identifying and accounting for domestic/pollutant pollutant contributions to
the POTV, in incorporating a safety factor during the limits setting process,
and in allocating allowable industrial pollutant loadings to individual
industrial users will be discussed.
3.3.1 Building in Safety Factors
The POTV should consider allocating only a portion of the maximum
allowable headvorks loading for each pollutant to the POTV's current
industrial and domestic users. The remaining portion of the maximum allowable
headworks loading for each pollutant is held in reserve as a safety factor.
This safety factor should be designed to account for and accommodate the
various uncertainties inherent in the local limits development process. These
uncertainties include:
Potential future industrial growth, resulting in new and/or increased
industrial discharges to the POTV.
Potential slug loadings (e.g., as a result of chemical spills) of
pollutants which might affect POTV operation/performance.
e Variability and measurement error associated with POTV design/
performance parameters used in deriving local limits (e.g., removal
efficiencies, POTV flow data, domestic/background pollutant levels,
etc.).
The determination of an appropriate safety factor is a site-specific
issue dependent upon local conditions. As noted above, a significant consid-
eration in the selection of an appropriate safety factor is the expected local
industrial growth rate and the expected impact this growth rate will have on
the POTV. Thus the POTV should endeavor to keep informed of proposed local
3-27
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industrial construction projects which might result in future increases in
pollutant loadings to the POTV. In the absence of more specific industrial
growth rate data, the POTV may wish to consider the following trends
indicative of industrial growth:
Trend analysis of POTV influent flows and pollutant loadings over the
past several years
Trend analysis of community water consumption records over the past
several years
Known/projected increases in the number of industrial building permits
issued
Known/projected increases in community revenues obtained through local
taxes
As a general rule, a minimum safety factor of ten percent of the maximum
allowable headworks loading is usually necessary to adequately address the
safety factor issues delineated in this section. As noted previously, the
requisite magnitude of the safety factor above this recommended minimum is a
site-specific issue; however, the POTV should recognize that selection of a
high safety factor does not constitute an appropriate substitute for periodic
review and updating of local limits. As local conditions change, the POTV
needs to periodically review and revise its local limits as necessary.
3.3.2 Domes tic/Background Contributions
Maximum allowable headworks loadings are allocated to total
domestic/background sources and to individual industrial/commercial users
during the limits setting process. For each pollutant the estimated total
loading currently received at the POTV from all domestic/background sources is
subtracted from the pollutant's allowable headworks loading. The resulting
allowable industrial/commercial loading can then be allocated to the
individual industrial users and local limits subsequently derived.
Domestic pollutant loadings for use in local limits calculations must be
obtained through site-specific monitoring. Such monitoring should be con-
ducted at sewer trunk lines which receive wastewater solely from domestic
sources. Domestic pollutant concentrations obtained as a result of this
3-28
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monitoring program are multiplied by the POTV's total domestic flow [as well
as the appropriate conversion factor], to derive the POTV's total domestic
loadings. These total domestic loadings are presumed to constitute background
loadings and are not typically controlled by local limits.
Table 3-13 presents typical domestic/background wastewater levels for
metals and nonmetal inorganics. These data were extracted from the 40 POTV
Study and a similar study of four cities. The Table 3-13 data provide only a
rough indication of the expected magnitude of site-specific domestic/back-
ground wastewater pollutant levels. Actual site-specific data should be used
in the derivation of the above-described domestic/background pollutant load-
ings whenever possible. The POTV is strongly urged to obtain site-specific
data by instituting an appropriate collection system monitoring program.
Occasionally, in deriving local limits for a particular pollutant, a POTV
may find that the total domestic/background loading of that pollutant ap-
proaches or exceeds the maximum allowable headworks loading. In such an
event, little or no portion of the maximum allowable headworks loading would
be available to allocate to industrial users. Such a situation may be
attributable in part to nondomestic facilities such as gasoline stations,
radiator shops, car washes, and automobile maintenance shops, which often
discharge at surprisingly high pollutant levels. These facilities are often
overlooked by POTVs, owing to their small size and low discharge flows, but
their discharges are controllable and should not be overlooked.
Tap water discharged to the city sewers contains background levels of
certain pollutants (e.g., chloroform, copper, zinc). These pollutants
sometimes originate from corroding water pipes or municipal water treatment
practices and can sometimes be controlled. These background levels contribute
to the POTV's total domestic pollutant loadings. In addition, household
wastes, such as household pesticides, solvents, and spent oil, discarded into
the city sewer will likewise contribute to the POTV's total domestic/back-
ground pollutant loadings.
Vhen the total domestic/background loading of a pollutant exceeds the
pollutant's maximum allowable headworks loading, the POTV should:
3-29
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Ensure that all significant industrial and commercial dischargers of
the pollutant have been identified.
Consider public education to reduce household discharges of used oil
and hazardous wastes.
Substitute actual sewer trunk line monitoring data for any literature
data used in deriving total domestic pollutant loadings to the POTV.
Substitute POTV removal efficiencies obtained as a result of in-plant
monitoring for any literature removal efficiencies used in deriving
maximum allowable headworks loadings.
Verify applicability of POTV plant and environmental protection
criteria (e.g., ensure that water quality criteria are appropriate for
the stream use classification of the POTV's receiving stream).
If the POTV's biological treatment units have never experienced
inhibition/upsets, compare inhibition-based maximum allowable head-
works loadings derived from literature inhibition data with the POTV's
current headworks loadings. If the current headworks loadings are
less stringent, but can be verified as having never inhibited or upset
the POTV's treatment processes, these loadings may constitute a more
appropriate local limits basis than the more stringent headworks
loadings derived from literature inhibition data.
By pursuing the problem in a logical manner, the POTV should be able to de-
velop reasonable local limits for pollutants with elevated total domestic/
background loadings.
3.3.3 Alternative Allocation Methods
Once the POTV has derived the maximum allowable industrial loadings of
the various pollutants, these loadings should be allocated to the POTV's in-
dustrial users. A variety of procedures exist for conducting these loading
allocations. In this section of the manual, four of the most commonly em-
ployed allocation methods - the uniform concentration method based on total
industrial flow, the concentration limit method based on industrial contribu-
tory flow, the mass proportion method, and the selected industrial reduction
method - will be described. In the following two subsections, the principal
considerations in applying these loading allocation methods to derive local
limits for conservative pollutants and nonconservative pollutants, respective-
ly, will be presented. Conservative pollutants are defined as pollutants
which are presumed not to be destroyed, biodegraded, chemically transformed,
3-30
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or volatilized within the POTV. Conservative pollutants introduced to a POTV
ultimately exit that POTV solely through the POTV's discharge streams (e.g.,
POTV effluent, sludge). Nonconservative pollutants are defined as pollutants
which are, to some degree, changed within the POTV by these mechanisms.
3.3.3.1 Conservative Pollutants
As suggested above, the uniform concentration method based on total
industrial flow, the concentration limit method based on industrial contribu-
tory flow, the mass proportion method, and the selected industrial reduction
method are all commonly used to allocate maximum allowable industrial loadings
and to subsequently derive local limits for conservative pollutants. The uni-
form concentration method based on total industrial flow yields one set of
limits that apply to all IUs, while the other three methods can be termed
"IU-specific", meaning that different limits apply to different IUs. Each of
the four methods is described below; equations for application of these
methods are provided in Figure 3-2:
1) Uniform concentration limit for all industrial users - For each
pollutant, the maximum allowable industrial loading to the POTV is
divided by the total flow from all industrial users, even those that
do not discharge the pollutant. This allocation method results in a
single discharge concentration limit for each pollutant that is the
same for all users. Mathematically, this method is the same as the
"flow proportion allocation method" described in earlier guidance
(Guidance Manual for POTV Pretreatment Program Development, U.S. EPA
Office of Vater Enforcement and Permits, Washington, DC, October,
1983, Appendix L.)
2) Concentration limits based on industrial contributory flow - This is
similar to the uniform concentration limit allocation method except
that' the flow from only those users that actually have the pollutant
in their raw wastewaters at greater then background levels is used to
derive a concentration limit for the pollutant. The limit for the
pollutant applies only to those identified users.
3) Mass proportion - For each pollutant, the maximum allowable indus-
trial loading to the POTV is allocated individually to each IU in
proportion to the IU's current loading. The limits are derived by
determining the ratio of the allowable headworks loading to the
current headworks loading, and then multiplying this ratio by each
IU's current loading.
4) Selected industrial reduction - The POTV selects the pollutant
loading reductions which each IU will be required to effect.
Typically, the POTV selects pollutant loading reductions on the basis
of treatability.
3-31
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Uniform Concentration
Method Based on Total
Industrial Flow:
'LIM
Equation
lall
(8.34)(Qind)
Concentration Limit
Method Based on Industrial
Contributory Flow:
Mass Proportion Method:
'LIM
JALL
(8*34^QC0NT)
Lall(x) - ^CURR(X) x Lall
CURR(T)
CLIM(X) = ALlj(X)
Selected Industrial
Reduction Method:
(8.34)(Q(X))
LALL(X) = LCURR(X) x <1"R(X)^
LIM
ALL
'I ND
*CONT
ALL(X)
CURR(X)
CURR(T)
ALL
'L I M ( X )
( X )
( X )
'LIM(X)
JALL(X)
(8.34)(Q(X))
= Uniform concentration limit, mg/1
= Maximum allowable industrial loading to the POTV, lbs/day
= Total industrial flow, MGD
= Industrial contributory flow, MGD
= Allowable loading allocated to industrial user X, lbs/day
= Current loading from industrial user X, lbs/day
= Total current industrial loading to the POTV, lbs/day
= Maximum allowable industrial loading to the POTV, lbs/day
= Discharge limit for industrial user X, mg/1
= Discharge flow from industrial user X, MGD
= POTV-selected pollutant removal efficiency for industrial user X,
as a decimal
FIGURE 3-2. COMMONLY USED METHODS TO ALLOCATE MAXIMUM
ALLOWABLE INDUSTRIAL LOADINGS
3-32
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The Appendix I local limits derivation example demonstrates the
application of each of these pollutant loading allocation techniques.
The relative advantages and disadvantages of each technique are a matter
of perception and philosophy as well as a matter of technical merit. A brief
discussion of the relative advantages and disadvantages of each technique is
provided below. This manual updates the material presented in Appendix L of
the EPA document, Guidance Manual for POTV Pretreatment Program Development
(October 1983).
Uniform Concentration Limits for All Industrial Users
This is the traditional method for deriving local limits. It is the only
method that results in local limits that are the same for all IUs. This is
because the total industrial flow is used in the calculations, not just the
flow from industries discharging the pollutant. Since uniform concentration
limits apply to all industrial users, these limits can be incorporated
directly into the POTV ordinance. Enforcement of the limits solely through
the ordinance without an independent control mechanism may be acceptable for
smaller POTWs with few IUs. However, an individual control document for each
IU is still desirable to specify monitoring locations and frequency, reporting
requirements, special conditions, applicable categorical standards, and to
provide clear notification to IUs as required by 40 CFR 403.8.
The relative ease of calculation and perceived ease of*application are
cited as major advantages of the uniform concentration approach. However,
this method also has several drawbacks which should be understood before a
decision is made to establish one target for all users.
The total industrial flow is used in the calculations. This has the
effect of allowing all nondomestic sources to discharge all limited pollutants
at levels up to the uniform concentration limits. All nondomestic sources
generally do not discharge measurable quantities of all limited pollutants;
however, the uniform concentration allocation method nevertheless provides
every IU with a flow proportioned pollutant loading allocation for every
limited pollutant. This practice may be acceptable if there is sufficient
excess capacity at the POTV. But this method can result in overly restrictive
3-33
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limits on IUs if the POTV discharges to a low-flow stream, operates a sensi-
tive process such as nitrification, or is faced with stringent sludge disposal
requirements. If the ability of the POTV to accept industrial pollutant
loadings is limited, adopting an allocation method that yields IU-specific
local limits may be the better course to pursue. Following are several
approaches to IU-specific local limits.
Concentration Limits Based on Industrial Contributory Flow
Discharge standards can also be developed for those specific IUs which
actually discharge a given pollutant. Under this scenario, a common discharge
limit would be established for all IUs identified as discharging a given
pollutant.
Under this method, whether the flow from the classification of a particu-
lar discharger is considered as either part of the domestic/background flow
or as part of the industrial contributory flow will depend on the particular
pollutant being considered. For example, if an industrial or commercial user
does not discharge cadmium or discharges only at background levels, then that
user's flow would be considered in the domestic portion of total POTV flow.
However, if a limit is being calculated for zinc and the same user discharges
zinc, then the user's flow is considered part of the industrial flow portion.
Some POTVs may have developed limits using this method and applied the
limits uniformly in the local ordinance without individual IU control docu-
ments. This approach should be avoided because ordinance limits normally
apply to all industrial users, not just those IUs identified as discharging
the particular pollutant. If additional IUs, outside of those IUs whose flows
were incorporated into the loading allocation process, were to begin discharg-
ing at pollutant levels up to the ordinance limit, then the POTVs allowable
headworks loading could potentially be exceeded, even though all IUs would be
discharging in compliance with the city's ordinance limits. In order to
ensure that this does not happen, a control mechanism should be used which
clearly notifies those IUs that they are expected to discharge at only their
current level, or the level assumed in the allocation process.
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A similar issue concerning this allocation method pertains to IUs that
have a pollutant present at significant concentrations in their raw wastewater
but at only background concentrations in their pretreated wastewater. These
IUs are often considered part of the domestic/background flow rather than the
industrial flow. This practice should be avoided unless the IU's control
document requires the discharge to remain at or below the current or back-
ground level. Again, the concern is that if the IU were to increase its
discharge up to the ordinance limit, perhaps due to poor operation of pre-
treatment equipment, the POTW's allowable headworks loading could be exceeded.
When used properly, the allocation method has advantages in that the
POTVs allowable loading is apportioned only to those IUs that actually
discharge a pollutant. A possible disadvantage of this approach is that it
requires detailed knowledge of each IU's current raw wastewater composition.
Mass Proportion Limits
These are limits developed on the basis of the ratio of allowable
headworks loading to current headworks loading for a particular pollutant.
This ratio is multiplied by the current loading for each IU, generating the
IU's local limit for that pollutant. When the current headworks loading
exceeds the maximum allowed, the requisite pollutant loading reductions are
imposed on all IUs. This method is particularly useful when the fate of the
pollutant within the collection system is not easily quantified. However,
this method requires a fairly detailed understanding of each user's effluent
quality and may penalize IUs which are presently pretreating their wastes when
others are not.
The mass proportion allocation method is an IU specific method; for each
pollutant, a different concentration limit is derived for each IU discharging
the particular pollutant. As local limits derived by the mass proportion
method are IU specific, these limits are most effectively implemented through
individual IU control documents.
Selected Industrial Reduction Limits
Selected industrial reduction limits are based on POTW-selected pollutant
loading reductions which certain IUs will be required to effect. The POTW
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generally bases these removals on vastevater treatability information.
Technology-based limitations are developed by considering the potential
vastevater treatment systems that are best suited to that Ill's vastevater.
Development of limits requires information about current IU loadings and
information on applicable industrial waste treatment and waste minimization
technologies. (See Chapters 5 and 6.)
This method seeks to cost-effectively reduce pollutant loadings by
imposing needed reductions on only the significant dischargers of a pollutant
on a case-by-case basis. Significance can be defined in terms of size, raw
waste loadings or concentrations, or potential to impact the POTV. Less
significant dischargers of the pollutant do not have to bear as much of the
pollutant reduction burden.
An advantage of this method is that it enables a POTV to focus its local
limits strategy for a particular pollutant on those specific industries for
vhich available technology vill bring about the greatest POTV influent loading
reductions. This approach may bring about the greatest pollution abatement
for the least amount of money. IUs that are in direct competition or are in
the same type of industry can be categorized and required to achieve the same
levels of pretreatment, which provides some equity and uniformity. However,
since uniform requirements are not imposed on all IUs, the POTV's decisions
will be subject to close examination and involvement by IUs.
The selected industrial reduction allocation method is IU specific,
establishing different concentration limits for different IUs. As with other
IU specific methods (i.e., industrial contributory flow and mass proportion
methods), local limits derived by the selected industrial reduction method are
most effectively implemented through individual IU control documents.
The selected industrial reduction method can be effectively used to set
local limits for nonconservative pollutants. Other pollutant loading alloca-
tion methods (e.g., uniform concentration method) involve the assumption that
pollutants are not lost through biodegradation/volatilization in the collec-
tion system. The selected industrial reduction methodology circumvents this
assumption by setting IU-specific local limits on the basis of expected IU
treatment technology performance.
3-36
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3.3.3.2 Nonconservative Pollutants
The allocation of allowable pollutant headvorks loadings for nonconserv-
ative pollutants presents unique challenges that are not encountered with
conventional pollutants. These challenges result from the fact that there
will be losses of nonconventional pollutants in the collection system, through
biodegradation and/or volatilization, losses which could be quite substantial.
As a result, any mass balance based approach to pollutant allocation is
complicated by losses through the collection system.
Because of these difficulties, it is recommended that POTVs adopt a more
empirical approach to establishing the discharge limits. This would involve
the following process:
Step One - Estimate the portions of nonconservative pollutants
contributed by controllable and noncontrollable sources.
This characterization will be difficult for nonconserva-
tive pollutants since the total domestic loading is
difficult to determine and thus the fraction lost in the
severs through volatilization and biodegradation may be
very difficult to determine. Of necessity, the assess-
ment must be based on a site specific consideration of
all available monitoring and sampling data as well as
sewer system configuration.
Step Two - Determine the percent pollutant reducti-on desired at the
plant headworks by comparing the maximum allowable
nonconservative pollutant headworks loading to the
existing loading.
Step Three - Require reduction in the industrial user discharges of
the nonconservative pollutant of concern at a minimum by
the above determined percentage. These minimum indus-
trial reductions may need to be increased further to
account for the uncontrolled loading from domestic/
background sources if the assessment called for in Step 1
suggests that those loadings may he significant.
Step Four - These limits, as with all local limits, should be
reassessed during the routine evaluation of local limit
effectiveness. If subsequent evaluation of the actual
influent loading indicates insufficient reduction has
been achieved, the POTV should consider whether the
industrial reductions called for in Step 3 need to be
increased.
3-37
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A demonstration of this pollutant loading allocation procedure is
provided in the local limits derivation example presented in Appendix I.
Potential collection system effects, such as flammability/explosivity and
fume toxicity, constitute additional bases for the development and implementa-
tion of local limits for volatile organics. These local limits bases are
discussed in detail in Chapter 4.
3.4 REVIEWING TECHNOLOGICAL ACHIEVABILITY
Once the POTV has derived its local limits in accordance with the
procedures presented in this Chapter, the POTV should determine whether the
limits are achievable through the installation of pretreatment technologies.
One result of a technological achievability assessment might be the decision
to rework the local limits calculations via an alternative allocation proced-
ure. One allocation procedure (selected industrial reduction) incorporates
technological achievability data into the allocation process. The technologi-
cal achievability assessment might also provide the POTV with an indication of
the stringency of its selected safety factor. Chapter 6 presents more
detailed discussions of technological achievability and local limits.
3.5 PRELIM
PRELIM (an acronym for "pretreatment limits") is an EPA computer program
that derives local limits for metals and cyanide, using the steady state
equations discussed in this chapter. PRELIM requires the user to enter site-
specific industrial user and POTV monitoring data as well as pertinent
in-plant criteria from which to base local limits. If site-specific data are
not available, PRELIM allows the user to access literature data for many
parameters.
It should be emphasized that PRELIM is merely a tool for POTUs to use in
deriving sound technical local limits on a site-specific basis. PRELIM, like
any other computer program, is not an appropriate substitute for sound
judgment on the part of its users, in assessing the site-specific validity of
its data outputs.
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TABLE 3-1. EPA AMBIENT WATER QUALITY CRITERIA FOR PROTECTION OP AQUATIC LIFE
Maximum Allowable Levels for Protection of Aquatic Life, pg/l+
Pollutant
Metals/Nonmetal Inorganics:
Antimony
Arsenic
Beryllium
Cadmium*
Chromium
(hex)
Chromium
(tri)
Copper
Cyanide
Lead
Mercury
Nickel
Freshwater Aquatic Life
Chronic Acute
1600
190
5.3
1.1*
11
210*
12*
5.2
3.2*
0.012
160*
9000
360
130
3.9*
16
1700*
18*
22
82
2.4
1400*
Saltwater Aquatic Life
Chronic
Acute
69
9.3
50
5.6
.025
8.3
36
43
1100
10,300
2.9
1
140
2.1
75
+from Reference [25]
*at 100 mg/1 hardness as CaC03
-------
TABLE 3-1. EPA AMBIENT WATER QUALITY CRITERIA FOR FOR PROTECTION OP AQUATIC LIFE (Continued)
Maximum Allowable Levels for Protection of Aquatic Life, ug/1
OJ
I
O
Pollutant
Selenium
Silver
Thallium
Zinc
Organics:
Acenaph thene
Acryloni trile
Aldrin
Benzene
Carbon Tetrachloride
Chlordane
Chlorinated Benzenes
1.1.1-Trichloroethane
1.1.2-Trichloroethane
Hexachloroe thane
Freshwater Aquatic Life
Chronic
Saltwater Aquatic Life
35
0.12
40
110*
520
2600
0.0043
50
9400
540
Acute
260
4.1
1400
120*
1700
7550
3
5,300
35200
2.4
250
18000
18000
980
Chronic
54
86
710
700
0.004
129
Acute
410
2.3
2,130
95
970
1.3
5,100
50000
0.09
160
31200
940
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TABLE 3-1. EPA AMBIENT WATER QUALITY CRITERIA FOR PROTECTION OF AQUATIC LIFE (Continued)
Maximum Allowable Levels for Protection of Aquatic Life, ug/1
i
t-
Pollutant
Pentachloroe thane
1,1,2,2-Te trachloroethane
1,1,1,2-Tetrachloroethane
Chlorinated Naphthalenes
2,4,6-Trichlorophenol
Chloroform
2-Chlorophenol
DDT
Dichlorobenzenes
Dichloroethylenes
2, 4-Dichlorophenol
Dichloropropanes
Dichloropropenes
Dieldrin
2,4-Dimethyl Phenol
Freshwater Aquatic Life
Chronic
1100
2400
970
1240
2000
0.0010
763
365
5700
244
0.0019
Acute
7240
9320
9320
1600
28900
4380
1.1
1120
11600
2020
23000
6060
2.5
2120
Saltwater Aquatic Life
Chronic Acute
281 390
9020
0.0010
3040
0.0019
7.5
0.13
1970
224000
10300
790
0.71
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TABLE 3-1. EPA AMBIENT WATER QUALITY CRITERIA FOR PROTECTION OF AQUATIC LIFE (Continued)
Maximum Allowable Levels for Protection of Aquatic Life, pg/1
Freshwater Aquatic Life
Pollutant
2.4-Dini trotoluene
Endosulfan
Endrin
Ethyl Benzene
Fluoranthene
Heptachlor
Hexachlorobenzene
Hexachlorobutadiene
Hexachlorocylohexane
Isophorone
Malathion
Me thoxychlor
Naphthalene
Ni trobenzene
Ni trophenols
Chronic
230
0.056
0.0023
0.0038
9.3
0.080
0.1
620
150
Acute
330
0.22
0.18
32000
3980
0.52
90
2.0
117000
0.03
2300
27000
230
Saltwater Aquatic Life
Chronic Acute
370
0.0087
0.0023
16
0.0036
0.1
590
0.034
0.037
430
40
0.053
32
0.16
12900
0.03
2350
6680
4850
-------
TABLE 3-1. EPA AMBIENT WATER QUALITY CRITERIA FOR PROTECTION OP AQUATIC LIFE (Continued)
Maximum Allowable Levels for Protection of Aquatic Life, ug/1
Freshwater Aquatic Life Saltwater Aquatic Life
Pollutant Chronic Acute Chronic Acute
Pentachlorophenol 13 20 7.9 13
Phenol 2560 10200 - 5800
Polychlorinated Biphenyls 0.014 2.0 0.030 10
Tetrachloroethylene 840 5280 450 10200
Toluene - 17500 5000 6300
Toxaphene 0.0002 0.73 0.0002 0.
Trichloroethylene 21900 45000 - 2000
Reference [25J: U.S. EPA-Quality Criteria for Water 1986, EPA 440/5-86-001 May 1, 1986.
-------
TABLE 3-2. ACTIVATED SLUDGE INHIBITION THRESHOLD LEVELS
Pollutant
Minimum Reported
Inhibi tion
Threshold
rcg/1
Metals/Nonmetal Inorganics
Cd
Cr (Total)
Cr (III)
Cr (VI)
Cu
Pb
Ni
Zn
As
Hg
Ag
CN
Ammonia
Iodine
Sulfide
Organics:
Anthracene
Benzene
1
1
10
1
1
0.1
0.08
0.1
0.1
0.25
0.1
480
10
25
500
100
Reported Range
of Inhibition
Threshold
Level, mg/1
1 - 10
1 - 100
10 - 50
1
1
0.1 - 5.0
10 - 100
1.0 - 2.5
5
0.08 - 5
5-10
0.1
0.1 - 1
2.5 as Hg (II)
0.25-5
0.1 - 5
5
480
10
25 - 30
100
125
500
500
500
Laboratory,
Pilot, or
Full-scale
Unknown
Pilot
Unknown
Unknown
Pilot
Unknown
Lab
Unknown
Pilot
Unknown
Pilot
Unknown
Unknown
Lab
Unknown
Unknown
Full
Unknown
Unknown
Unknown
Lab
Unknown
Laboratory
References*
(29), (32)
(28)
(29), (32)
(29), (32)
(29), (28), (32)
(32)
(28)
(29), (32)
(28)
(32)
(28)
(28), (29), (
(29), (32)
(28)
(29), (32)
(28), (29), (32)
(28)
(46)
(46)
(46)
(28)
(32)
(28)
*References did not distinguish between total or dissolved pollutant inhibition levels.
3-44
-------
TABLE 3-2.
ACTIVATED
SLUDGE INHIBITION
THRESHOLD LEVELS
(Continued)
Minimum Reported
Inhibition
Threshold
Pollutant mg/1
Reported Range
of Inhibition
Threshold
Level, mg/1
Laboratory,
Pilot, or
Full-scale
References*
2-Chlorophenol
5
5
20 - 200
Unknown
Unknown
(29)
(32)
1,2 Dichlorobenzene
5
5
Unknown
(29)
1,3 Dichlorobenzene
5
5
Unknown
(29)
1,4 Dichlorobenzene
5
5
Unknown
(29)
2,4-Dichlorophenol
64
64
Unknown
(32)
2,4 Dimethylphenol
50
40 - 200
Unknown
(32)
2,4-Dinitrotoluene
5
5
Unknown
(29)
1,2-Diphenylhydrazine
5
5
Unknown
(29)
Ethylbenzene
200
200
Unknown
(32)
Hexachlorobenzene
5
5
Unknown
(29)
Naphthalene
500
500
500
500
Lab
Unknown
Unknown
(28)
(29)
(32)
Ni trobenzene
30
30 - 500
500
500
Unknown
Lab
Unknown
(32)
(28)
(29)
Pentachlorophenol C
). 95
0.95
50
75 - 150
Unknown
Unknown
Lab
(29)
(32)
(28)
Phenathrene
500
500
500
Lab
Unknown
(28)
(29)
Phenol
50
50 - 200
200
200
Unknown
Unknown
Unknown
(32)
(29)
(28)
Toluene
200
200
Unknown
(32)
2,4,6 Trichlorophenol
50
50 - 100
Lab
(28)
Surfactants
100
100 - 500
Unknown
(46)
*References did not distinguish between total or dissolved pollutant inhibition levels.
3-45
-------
TABLE 3-3. TRICKLING FILTER INHIBITION THRESHOLD LEVELS
Pollutant
Cr (III)
CN
Minimum Reported
Inhibi tion
Threshold
mg/1
3.5
30
Reported Range
of Inhibition
Threshold
Levels, mg/1
3.5 - 67.6
30
Laboratory,
Pilot, or
Full-scale
Full
Full
References*
(28)
(28)
*Reference did not distinguish betveen total or dissolved pollutant inhibition levels
3-46
-------
TABLE 3-4. NITRIFICATION INHIBITION THRESHOLD LEVELS
Pollutant
Minimum Reported
Inhibi tion
Threshold
mg/1
Metals/Nonmetal Inorganics
Cd
Cr (T)
Cr (VI)
Cu
Pb
Ni
Zn
5.2
0.25
1
0.05
1.5
0.25
0.08
Reported Range
of Inhibition
Threshold
Levels, mg/1
5.2
0.25 - 1.9
1 - 100
(trickling
filter)
1 - 10
0.05 - 0.48
0.5
0.25
0.08
0.5
5
0.5
Laboratory,
Pilot, or
Full-scale
Laboratory
Unknown
Unknown
(as Cr042")
Unknown
Unknown
Unknown
Pilot
Unknown
References*
(28), (29)
(28), (29), (32)
(28)
Unknown
(29), (32)
(29), (32)
(29), (32)
(28)
(29), (32)
(28)
\s
CN 0.34
Chloride
Organics;
Chloroform 10
24-Dichlorophenol 64
2,4-Dinitrophenol 150
Phenol 4
1.5
0.34 - 0.5
180
10
64
150
4
4-10
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
(29)
(29), (32)
(46)
(29)
(32)
(29)
(29)
(32)
^References did not distinguish between total or dissolved pollutant inhibition levels
3-47
-------
TABLE 3-5. ANAEROBIC DIGESTION THRESHOLD INHIBITION LEVELS
Pollutant
Recommended
Inhibition
Threshold*
(mg/1)
Metals/Nonmetal Inorganics
Cd 20
Cr (VI) 110
Cr (III) 130
Cu 40
Pb 340
Ni 10
Zn
As
Hg
CN
Ammonia
Sulfate
Sulfide
400
1.6
13**
4
4
1500
500
50
Reported Range
of Inhibition
Threshold*
Level, mg/1
20
110
130
40
340
10
136
400
1.6
13-65**
4-100
1-4
1500 - 8000
500 - 1000
50 - 100
Laboratory,
Pilot, or
Full-scale
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
References
(32)
(32)
(32)
(32)
(32)
(29), (32)
(28)
(32)
(28)
(32)
(28)
(29), (32)
(46)
(46)
(46)
Organics:
Acrylonitrile 5
Carbon Tetrachloride 2.9
Chlorobenzene
0.96
5
5
2.9 - 159.4
10 - 20
2.0
0.96 - 3
0.96
Unknown
Unknown
Lab
Unknown
Unknown
Lab
Unknown
(32)
(29)
(28)
(32)
(29)
(28)
(29)
3-48
-------
TABLE 3-5. ANAEROBIC DIGESTION THRESHOLD INHIBITION LEVELS (Continued)
Pollutant
Chloroform
Methylchloride
Pentachlorophenol
Recommended
Inhibi tion
Threshold
(mg/1)
1
1,2-Dichlorobenzene 0.23
1,4-Dichlorobenzene 1.4
3.3
0.2
Tetrachloroethylene 20
Trichloroethylene 1
Trichlorofluoromethane
Reported Range
of Inhibition
Threshold
Level, mg/1
1
5-16
10 - 16
0.23 - 3.8
0.23
1.4 - 5.3
1.4
3.3 - 536.4
100
0.2
0.2 - 1.8
20
1-20
20
20
Laboratory,
Pilot, or
Full-scale
Unknown
Lab
Unknown
Lab
Unknown
Lab
Unknown
Pilot
Unknown
Unknown
Lab
Unknown
Lab
Unknown
Unknown
Unknown
References
(29)
(28)
(32)
(28)
(29)
(28)
(29)
(28)
(29)
(29)
(28)
(29)
(28)
(29)
(32)
(29)
~Total pollutant inhibition levels, unless otherwise indicated
~~Dissolved metal inhibition levels
3-49
-------
TABLE 3-6. FEDERAL AHD SELECTED STATE SLUDGE DISPOSAL REGULATIONS AND GUIDELINES FOB METALS AND ORGAHICS
Cumulative Application Limits,
lbs/acre
Regulation Sludge Annual Soil Soil Soil
or Limit, Application CEC* CEC CEC
State Guideline Pollutant ag/kq dry wt. Linit, lbs/acre <5 m«q/100g 5-15 aeq/lOOq >15 meq/lOOg
Federal Regulation Cd - 0.4S (pH<6.5) 4.46 4.46 4.46
(40 CFR 257.3-5) (pH>6.5) 4.46 8.92 17.84
(Federal Register
June 1976)**
New Jersey
Guideline
Cd
-
0.45
(pH> 6.5)
4 . 46
8 . 92
17.84
Cu
-
-
(pH> 6.5)
111.5
223 .1
446.1
Pb
-
-
(pH> 6.5)
446 . 1
892 . 2
1784.4
Nl
-
-
(pH>6.5)
44.6
89.2
178 .4
Zn
-
-
(pH> 6.5 )
223.1
446 .1
892 . 2
Guideline
Cd
-
-
4.4
8.9
17 . 8
Cu
-
-
125
250
500
Pb
-
-
500
1 ,000
2,000
Ni
-
-
125
250
500
Zn
-
-
250
500
1,000
Contamination
Aldrin
o
o
Indicator
Chlordine
0.20
Endnn
0.10
DDT
0.25
PCBs
0 . 50
New York
Guideline
Cd
25
Cr
1 ,000
Cu
1 ,000
Pb
1 ,000
Nl
200
Hg
10
Zn
2,500
the
site's soil
- Environmental
0.45
4 . 46
111.5
446 .1
44.6
223
4 . 46
4.46
111 .5
446.1
44.6
223
if not known, contact the local Soil Extension Service.
"froB "Municipal Sludge Management - Environmental Factors." Federal Register, 41, NO. 108, pp. 22531, 22543. June 1976
111.5
446 .1
44.6
223
-------
TABUS 3-6. FEDERAL AHD SELECTED STATE SLUDGE DISPOSAL REGULATIONS AflD GUIDELINES FOB KETALS ASD OHGAHICS (Continued)
Minnesota
Regulation
o r
Guide line
Regulation
Ohio
Guide line
r
Texas
Regulation
Co 1o rado
Regulation
Cumulative Application Limits,
lbs/acre
Pollutant
Cd
S ludge
Limit,
mq/kq dry ut
Annual
Application
Limit, lbs/acre
0.5
(2 for application
Soi 1
CEC
<5 meq/lOOg
Soi 1
CEC
5-15 meq/lOOg
10
Soil
CEC
>15 meq/lOOg
20
Cu
to crops not for
human consumption)
125
250
500
Pb
-
-
500
1 ,000
2,000
Nl
-
-
50
100
200
Zn
-
-
250
500
1,000
Cd
0 . 4
(pH <6.5)
(pH>6.5)
4 . 5
4 . 5
4 . 5
8 . 9
4
17
Cu
125
250
500
Pb
500
1000
2000
Ni
125
250
500
Zn
250
500
1000
Cd
25
(Class
I t
II)
Cu
1,000
(Class
I)
Pb
500
1 ,000
(Class
(Class
I)
II)
N:
200
(Class
I)
Zn
2,000
(Class
I)
PCBs
10
(Class
I i
II)
Cd
-
|pH=4-6.5) 0.25
(pH> 6 . 5 ) 0.5
5
5
5
10
5
20
625
(Class
I)
(pH=4-6.5)
125
125
125
Cu
1 ,650
3,125
(Class
(Class
II) *
III)
*
(pH> 6.5)
125
250
500
250
(Class
I) "
(pH=4-6.51
50
50
50
Nl
650
1 ,250
(Class
(Class
III *
III )
ft
-
(pH> 6.5)
50
100
200
1,250 (Class I)'
(pH=4-6.5) 250 250 250
-------
B/834-5-J5-01c/#10
TABLE 3-6. FEDERAL ASD SELECTED STATE SLUDGE DISPOSAL REGULATIONS AND GUIDELINES FOR METALS ABO ORGAN ICS (Continued)
Regulation
or
Guida 1ina
Pollutant
Zn
Sludge
Limit,
mg/kq dry ut.
3,325 (Class II)*
6,250 (Class III)*
Annual
Application
Liait. lbs/acra
Cumulative Application Liaits,
lbs/acra
Soil
CEC
<5 aaq/lOOq
(pH>6.5) 250
Soil
CEC
5-15 maq/lOOq
500
Soil
CEC
>15 aeq/lOOq
1,000
Pb
PCBs
5 (Class I)'
10 (Class II i III)*
6.5) 500
500
1 ,000
500
2,000
California PCBs 5
'Class I Sludga = Application to private lawns, gardens
'Class II Sludge = Controlled usa in agricultural setting
'Class III Sludge - Application to nonfoodchain crops only
r
-------
TABLE 3-7. EP TOXICITY LIMITATIONS
Maximum
Pollutant Concentration, mg/1
As 5.0
Ba 100.0
Cd 1.0
Cr 5.0
Pb 5.0
Hg 0.2
Se 1.0
Ag 5.0
Endrin 0.02
Lindane 0.4
Methoxychlor 10.0
Toxaphene 0.5
2,4-D 10.0
2,4,5-TP 1.0
3-53
-------
TABLE 3-8. NICKEL LEVELS IN CHATTANOOGA POTV INFLUENT, EFFLUENT,
AND SLUDGE
(2/11-2/20/80)*
j
¦ 7
Influent
Effluent
Sludge Levels, ug/1
Date
Level, ug/1
Level, ug/1
Primary
Secondary
2/11/80
BDL**
87
2700
580
2/12/80
190
BDL
6600
480
2/13/80
76
BDL
3600
740
2/14/80
100
77
4100
840
2/15/80
66
58
2200
810
2/16/80
BDL
170
2700
710
2/17/80
58
BDL
4700
800
2/18/80
BDL
BDL
2700
930
2/19/80
200
95
9300
1300
2/20/80
120
58
17000
1200
~Samples collected were 24-hour composites for ten consecutive days.
**BDL = Below 50" ug/1 detection limit.
3-54
-------
TABLE 3-9. PRIORITY POLLUTANT REMOVAL EFFICIENCIES THROUGH
PRIMARY TREATMENT*
No. of POTVs
Metal/Nonmetal Inorganics Median vith Removal Data**
Cadmium
15
6
of
40
Chromium
27
12
of
40
Copper
22
12
of
40
Lead
57
1
of
40
Nickel
14
9
of
40
Zinc
27
12
of
40
Mercury
10
8
of
40
Silver
20
4
of
40
Cyanide
27
12
of
40
Organics
Benzene
25
8
of
40
Chloroform
14
11
of
40
1,2-trans-Dichloroethylene
36
9
of
40
Ethylbenzene
13
12
of
40
Tetra chloroethylene
4
12
of
40
1,1,1-Trichloroethane
40
10
of
40
Trichloroethylene
20
12
of
40
Butyl Benztyl phthalate
62
4
of
40
Di-n-butyl phthalate
36
3
of
40
Diethyl phthalate
56
1
of
40
Naphthalene
44
4
of
40
Phenol
8
11
of
40
*Pollutant removals between POTV influent and primary effluent. From Fate of
Priority Pollutants in Publicly Owned Treatment Works, Volume I (EPA
440/1-82/303), U.S. Environmental Protection Agency, Washington, D.C.,
September 1982, p. 61.
**Median removal efficiencies from a data base of removal efficiencies for 40
POTWs. Only POTVs with average influent concentrations exceeding three
times each pollutant's detection limit were considered.
3-55
-------
TABLE 3-10. PRIORITY POLLUTANT REMOVAL EFFICIENCIES THROUGH ACTIVATED SLUDGE
TREATMENT*
Metals/Nonmetal Inorganics**
Range
Second
Decile
Median
Eighth
Decile
No. of P0TW:
with Removal Da
Cadmium
25-99
33
67
91
19
of
26
Chromium
25-97
68
82
91
25
of
26
Copper
2-99
67
86
95
26
of
26
Lead
1-92
39
61
76
23
of
26
Nickel
2-99
25
42
62
23
of
26
Zinc
23-99
64
79
88
26
of
26
Arsenic
11-78
31
45
53
5
of
26
Mercury
1-95
50
60
79
20
of
26
Selenium
25-89
33
50
67
4
of
26
Silver
17-95
50
75
88
24
of
26
Cyanide
3-99
41
69
84
25
of
26
Organics**
Benzene
25-99
50
80
96
18
of
26
Chloroform
17-99
50
67
83
24
of
26
1,2-trans-Dichloroethylene
17-99
50
67
91
17
of
26
Ethylbenzene
25-99
67
86
97
25
of
26
Methylene chloride
2-99
36
62
77
26
of
26
Tetrachloroethylene
15-99
50
80
93
26
of
26
Toluene
25-99
80
93
98
26
of
26
1,1;1-Trichloroethane
18-99
75
85
94
23
of
26
Trichloroethylene
20-99
75
89
98
25
of
26
Anthracene
29-99
44
67
91
5
of
26
Bis (2-ethylhexyl) phthalate
17-99
47
72
87
25
of
26
Butyl Benzyl phthalate
25-99
50
67
92
16
of
26
Di-n-butyl phthalate
11-97
39
64
87
19
of
26
Diethyl phthalate
17-98
39
62
90
15
of
26
Napthalene
25-98
40
78
90
16
of
26
Phenanthrene
29-99
37
68
86
6
of
26
Phenol
3-99
75
90
98
19
of
26
Pyrene
73-95
76
86
95
2
of
26
*Pollutant removals between POTV influent and secondary effluent (including secondary
clarification). Based on a computer analysis of POTV removal efficiency data, (derived from
actual POTV influent and effluent sampling data) provided in Fate of Priority Pollutants in
Publicly Owned Treatment Works, Volume II, (EPA 440/1-82/303), U.S. Environmental Protection
Agency, Washington, D.C., September 1982.
**For the purpose of deriving removal efficiencies, effluent levels reported as below
detection were set equal to the reported detection limits. All secondary activated sludge
treatment plants sampled as part of the study were considered.
3-56
-------
TABLE 3-11. PRIORITY POLLUTANT REMOVAL EFFICIENCIES THROUGH TRICKLING FILTER
TREATMENT*
Second
Eighth
No. of POTVs
Metals/Nonmetal Inorganics**
Range
Decile
Median
Decile
with Removal Data
Cadmium
33-96
33
68
93
6 of 11
Chromium
5-92
34
55
71
9 of 11
Copper
12-97
32
61
89
9 of 11
Lead
4-84
25
55
70
6 of 11
Nickel
7-72
11
29
57
9 of 11
Zinc
14-90
34
67
81
9 of 11
Mercury
14-80
33
50
62
9 of 11
Silver
11-93
38
66
86
8 of 11
Cyanide
7-88
33
59
79
8 of 11
Organics**
Benzene
5-98
50
75
93
7 of 11
Chloroform
21-94
50
73
84
9 of 11
1,2-trans-Dichloroethylene
14-99
50
50
96
7 of 11
Ethylebenzene
45-97
50
80
91
10 of 11
Methylene chloride
5-98
28
70
85
10 of 11
Tetrachloroethylene
26-99
53
80
93
10 of 11
Toluene
17-99
80
93
97
10 of 11
1,1,1-Trichloroethane
23-99
75
89
97
10 of 11
;chloroethylene
50-99
67
94
98
10 of 11
bis (2-ethylhexyl) phthalate
4-98
21
58
81
10 of 11
Butyl benzyl phthalate
25-90
37
60
77
9 of 11
Di-n-butyl phthalate
29-97
41
60
82
10 of 11
Diethyl phthalate
17-75
40
57
67
8 of 11
Naphthalene
33-93
40
71
87
6 of 11
Phenol
50-99
75
84
96
8 of 11
*Pollutant removals between POTV influent and secondary effluent (including secondary
clarification). Based on a computer analysis of POTV removal efficiency data, (derived from
actual POTV influent and effluent sampling data) provided in Fate of Priority Pollutants in
Publicly Ovned Treatment Works, Volume II, (EPA 440/1-82/303)^ U.S. Environmental Protection
Agency, Washington, D.C., September 1982.
**For the purpose of deriving removal efficiencies, effluent levels reported as below
detection were set equal to the reported detection limits. All secondary trickling filter
plants sampled as part of the study were considered.
3-57
-------
TABLE 3-12. PRIORITY POLLUTANT REMOVAL EFFICIENCIES
TREATMENT*
THROUGH TERTIARY
Second
Eighth
No.
, of POTWs
Metals/Nonmetal Inorganics**
Range
Decile
Median
Decile
with
Removal Data
Cadmium
33-81
50
50
73
3 of 4
Chromium
22-93
62
72
89
4 of 4
Copper
8-99
58
85
98
4 of 4
Lead
4-86
9
52
77
3 of 4
Nickel
4-78
17
17
57
3 of 4
Zinc
1-90
50
78
88
4 of 4
Mercury
33-79
43
67
75
4 of 4
Silver
27-87
55
62
82
3 of 4
Cyanide
20-93
32
66
83
4 of 4
Organics**
Benzene
5-67
40
50
54
2 of 4
Chloroform
16-75
32
53
64
3 of 4
1,2-trans-Dichloroethylene
50-96
50
83
93
2 of 4
Ethylbenzene
65-95
80
89
94
3 of 4
Methylene Chloride
11-96
31
57
78
4 of 4
Tetrachloroethylene
67-98
80
91
97
4 of 4
Toluene
50-99
83
94
97
4 of 4
1,1,1-Trichloroethane
50-98
79
94
97
4 of 4
Trichloroethylene
50-99
62
93
98
4 of 4
Bis (2-ethylhexyl) phthalate
45-98
'59
76
94
4 of 4
Butyl benzyl phthalate
25-94
50
63
85
4 of 4
Di-n-butyl phthalate
14-84
27
50
70
4 of 4
Diethyl phthalate
20-57
29
38
50
3 of 4
Naphthalene
25-94
33
73
86
3 of 4
Phenol
33-98
80
88
96
4 of 4
*Pollutant removals between POTV influent and tertiary effluent (including final
clarification). Based on a computer analysis of POTV removal efficiency data, (derived from
actual POTV influent and effluent sampling data) provided in Fate of Priority Pollutants in
Publicly Owned Treatment Works, Volume II, (EPA 440/1-82/303), U.S. Enviromental Protection
Agency, Washington, D.C., September 1982.
Tertiary treatment was taken to include POTWs with effluent microscreening, mixed media
filtration, post aeration, and/or nitrification/denitrification.
**For the purpose of deriving removal efficiencies, effluent levels reported as below
detection were set equal to the reported detection limits. All tertiory treatment plants
sampled as part of the study were considered.
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TABLE 3-13. TYPICAL DOMESTIC WASTEWATER LEVELS*
Pollutant Concentration, mg/1
Cd 0.003
Cr 0.05
Cu 0.061
Pb 0.049
Ni 0.021
Zn 0.175
As 0.003
Hg 0.0003
Ag 0.005
CN 0.041
*From "Assessment of the Impacts of Industrial Discharges on Publicly Owned
Treatment Works, Appendices," prepared by JRfl Associates for the U.S.
Environmental Protection Agency, November 1981, p. C-38.
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4. LOCAL LIMITS DEVELOPMENT TO ADDRESS COLLECTION SYSTEM PROBLEMS
In this chapter, considerations in developing local limits based on
collection system effects are discussed. These collection system effects
include:
Fire/explosion
« Corrosion
Flow obstruction
Heat effects
Fume toxicity.
Each of the above effects, and the development of local limits based on
appropriate effects criteria, are discussed in the following sections.
4.1 IMPLEMENTATION OF SPECIFIC PROHIBITIONS
The specific prohibitions of the General Pretreatment Regulations [40 CFR
403.5(b)] forbid the discharge of pollutants which cause fire or explosion
hazards, corrosive structural damage, obstruction of flow, inhibition of
biological activity due to excessive heat, or interference with POTV
operations. The following sections outline methods for establishing local
limits for those pollutants which can cause violations of these prohibitions.
4.1.1 Fire and Explosion
In order to comply with the specific discharge prohibitions, and to pro-
tect the POTV and its workers from explosion or fire in the collection system
or treatment works, POTVs must develop a strategy for screening against dis-
charges which will cause flammable/explosive conditions. This strategy should
incorporate both field monitoring activities and review of data from industry
surveys and permit application forms. Where problem discharges are
identified, the POTW must impose local discharge limitations or other source
controls to mitigate the danger.
4-1
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The following procedures for establishing flammable/explosive pollutant
discharge limits and source control requirements are discussed in this
section:
Lower explosive limit (LEL) monitoring
Sample headspace monitoring
Flash point limitations
Industrial user management practice plans.
An LEL-based screening technique for identifying potential problem
discharges is also presented.
4.1.1.1 Lower Explosive Limit (LEL) Monitoring
The lower explosive limit (LEL) of a compound is the minimum
concentration of that compound, as a gas or vapor in air, which will explode
or burn in the presence of an ignition source. As part of their strategies
for detecting flammable/explosive discharges, many POTVs are currently
conducting routine explosimeter screening of LEL levels (i.e., measured vapor
levels of a pollutant expressed as a percentage of the pollutant's LEL) at key
sewer locations. These monitoring programs consist of routine screening of
manholes and/or continuous monitoring of pump stations, IU sewer connections,
etc. These monitoring programs provide an ongoing source of data that may
serve as the basis for more comprehensive programs of sampling and analyses to
positively identify the offending industries.
In implementing these programs, it is important that the POTV is aware of
the limitations to the LEL data that are collected. For instance, if detected
LEL levels are found to be high directly downstream from an industrial
discharge, and background levels (upstream) are lower, this does not
necessarily mean that the contributing industry is the cause of the measured
increase. Complicating factors in this analysis might include the turbulence
of the wastewater at each monitoring point, the method by which LEL measure-
ments were made (whether the reading was taken immediately after removal of a
manhole lid, or time allowed to elapse), and the degree of ventilation (air
exchange rate) at each point. Realizing these potentially complicating
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factors, the sampling crews vould be well advised to also sample the IU
discharge and perform an analysis for the volatile constituents. Collectively,
these data would provide convincing evidence in support of any IU controls
that the POTV should choose to require.
In addition to ongoing LEL monitoring programs, POTV workers should
always test sewer atmospheres for flammable/explosive conditions as a safety
precaution immediately prior to monitoring of the sewer. Section 4.2.4
discusses this and other POTV worker safety issues in more detail.
4.1.1.2 Sample Headspace Monitoring
There are a variety of methods for setting local limits to control the
discharge of flammable/explosive pollutants to POTVs. This section describes
one innovative approach, which has been successfully implemented by the
Cincinnati Metropolitan Sanitary District (MSD).
The MSD has established a volatile organic pollutant local limit, based
on a sample headspace monitoring technique. This headspace monitoring
technique consists of:
Collection of an IU discharge sample in accordance with proper
volatile organic sampling techniques (e.g., zero headspace, etc.)
Withdrawal of 50 percent of the sample (by volume), followed by
injection of nitrogen gas (to maintain one atmosphere total pressure)
Equilibration of sample
GC analysis of sample headspace gas.
The details of this sample headspace monitoring technique are provided in
Appendix J. The MSD requires total volatile organic levels in the sample
headspace gases to be below a 300 ppm hexane equivalent limit. This limit was
deemed sufficient to protect the collection system from fires/explosions and
to provide POTV workers minimal protection from pollutant fume toxicity (a
more stringent consideration). Worker health and safety issues associated
with the development of the MSD volatile organic pollutant local limit are
discussed in detail in Section 4.2.1.
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4.1.1.3 Flashpoint Limitation
Another local limits option for control of flammable/explosive pollutant
discharges is a flashpoint limitation imposed upon discharges to POTVs. Such
a prohibition would state that no discharge to a POTV shall possess a flash-
point below a stated value. This flashpoint prohibition would apply to all
wastes received at the POTV, including IU discharges, as well as wastes
received from waste haulers. A flashpoint screening of waste haulers' loads
would enable the POTV to readily ascertain whether ignitable wastes had been
accepted by the haulers.
The flashpoint is the minimum temperature at which vapor combustion will
propagate away from its source of ignition. At temperatures below the flash-
point, combustion of the vapor immediately above the liquid will either not
occur at all, or will occur only at the exact point of ignition. Temperatures
above the flashpoint are required for combustion to spread. Thus, a flashpoint
limitation ensures that no discharge to a POTV will independently result in
the propagation of self-sustained combustion.
It is important to emphasize that a flashpoint prohibition will not
necessarily account for the flammability of mixtures of multiple industrial
user discharges when combined in sewers. Owing to the effect of dilution
within the sewer system, however, it is generally reasonable to assume that
the concentrations of combustible constituents in sewer wastewaters will be
well below the concentrations required for flammability/explosivity, provided
that all industrial users are in compliance with the flashpoint prohibition.
A 140°F closed cup flashpoint is recommended as the appropriate limit for
the flashpoint prohibition. The 140°F closed cup flashpoint limit is proposed
for the following reasons:
Ambient temperatures are not likely to meet or exceed 140°F, either at
the point of discharge or within the sewer system
Typical industrial wastewater temperatures are considerable below
140°F
The closed cup flashpoint test is recommended because this test is
based upon the ignition of confined vapors, and thus simulates
potential sewer conditions
To aid cities in minimizing RCRA liabilities concerning the acceptance
of ignitable characteristic hazardous wastes.
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Although the 140°F flashpoint prohibition would be imposed upon waste-
water discharges and not wastewater constituents, a comparison of the relative
flashpoints of typical organic wastewater constituents would provide a rough
guide as to the stringency of the flashpoint prohibition. Table 4-1 cites the
closed cup flashpoints of several organic chemicals. It can be seen from this
table that wastewater discharges would have to be at least as nonflammable as
(pure) furfural or benzaldehyde to meet the flashpoint prohibition. Table 4-1
also demonstrates that a flashpoint prohibition would not permit the undiluted
discharge of volatiles such as gasoline or ethyl alcohol.
In order to measure the flashpoint of a wastewater sample, a flashpoint
tester must be obtained. A flashpoint tester is used to slowly heat the
sample, and at periodic intervals, a test flame is applied to the vapor space
above the liquid. The flashpoint is the temperature at which a flash of flame
is visible upon application of the test flame.
The Tagliabue (Tag) closed cup flashpoint tester is suggested as the
appropriate flashpoint tester for wastewater samples. The Tag tester is
designed to accommodate nonviscous, nonfilm-forming liquid samples with
flashpoints below 200°F. The American Society for Testing and Materials
(ASTM) states that Tag closed cup testers cost $1,000-31,500 and are available
through laboratory instrumentation supply firms. Tag closed cup flashpoint
test methodologies have been established by, and are available through, ASTM
as ASTM Methodology D-56. Operation of Tag testers requires no further
expertise beyond that of a competent laboratory chemist.
4.1.1.4 Industrial User Management Practice Plans
In addition to establishing a numeric local limit on the discharge of
flammable/explosive pollutants, the P0TV can often require IUs to submit
management practice plans. These plans document III procedures for handling
process chemicals and controlling chemical spills. The documented procedures
also detail IU measures taken to prevent flammable/explosive pollutant
discharges to the P0TW. IU implementation of proper chemical handling and
spill control procedures above can often effectively eliminate the possibility
of flammable/explosive pollutant discharges, thereby obviating the need for
4-5
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further control measures. Chapter 5 discusses industrial user management
practice plans in more detail.
4.1.1.5 Screening Technique for Identifying Flammable/Explosive Pollutant
Discharges
In order to identify IU discharges which could potentially generate
flammable/explosive conditions in sewer atmospheres, an IU discharge screening
procedure should be established. This screening procedure would 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 LEL data into corresponding IU discharge screening
levels, and
(2) Comparison of these screening levels with actual IU discharge
levels. Exceedances may warrant further investigation by the POTV,
perhaps involving the flammable/explosive pollutant discharge
control measures discussed in Sections 4.1.1.1 to 4.1.1.4 above.
The calculation of LEL-based screening levels is a five-step process:
1. Determine the LEL of the pollutant of concern. LEL values are
typically expressed as percent (volume/volume)-in-air concentrations.
LEL values for several volatile organics are presented in the second
column of Table 4-2. Appendix F, as well as the LEL data sources
referenced in Appendix F, present LEL data for many additional
pollutants.
2. Convert the compound's LEL concentration (percent) to a vapor phase
concentration (CVAp) expressed in mol/m (third column of Table 4-2):
CVAp = LEL x x 10 mol/m3 (1)
where
CVAp = LEL expressed as a vapor phase concentration, mol/m3
LEL = Lower explosive limit, percent (volume/volume)
P = Total pressure, 1 atm (assumed)
R = Ideal gas constant, 0.08206 atm L/mol K
T = Temperature, 298.15K (assumed).
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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 concentrations, as are normally encountered
in IU discharges. Table 4-3 presents Henry's Lav Constants (in
various units) for several of the organics listed in Appendix G.
Henry's Law Constants for additional pollutants are provided in
Appendix G, as well as in the literature sources referenced in Table
4-3.
4. Convert the Henry's Law Constant to the appropriate units. The
Henry's Law Constants presented in Table 4-3 are expressed in terms
of three different units:
(atm m3)/mol
(mol/m3)/(mg/L)
(mg/m3)/(mg/L).
In the literature, Henry's Law Constants are most commonly expressed
in terms of pressure (atm m /mol). To derive LEL-based screening
levels, however, the Henry's Law Constant must be expressed in terms
of (mol/m )/(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/m )/(mg/L):
H = H. x 1 X 10 (mol/m3/(mg/L)
-------
5. Calculate the IU discharge screening level using the Henry's Law
expression (fifth column of Table 4-2):
^VAP
L V L = (2)
H
where
Clvt = Discharge screening level, mg/L
CVAp = LEL expressed as a vapor phase concentration, mol/m3
H = Henry's Lav Constant (mol/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, see assumptions delineated
below) and does not take into account dilution of IU wastewater
within the collection system.
Table 4-2 presents LEL-based screening levels, calculated using the
method described above, for several pollutants selected from the list of
pollutants presented in Appendix G. The screening levels vary over a
considerable range (from 11 mg/L for chloromethane to 24,848 mg/L for methyl
ethyl ketone), and are influenced significantly by the magnitude of the
Henry's Law Constant, such that:
Compounds with relatively lower Henry's Law Constants, such as methyl
ethyl ketone, possess higher screening levels, and
Compounds with relatively high Henry's Law constants, such as
chloromethane, possess lower screening levels.
The following assumptions are made when adopting the Henry's Law
expression for calculation of LEL-based screening levels:
Temperature dependency of the Henry's Law Constant - The Henry's Law
Constant is typically calculated as the ratio of a compound's vapor
pressure (in atmospheres) to its solubility (in mol/m ). Because both
vapor pressure and solubility are temperature dependent, the Henry's
Lav Constant is also temperature dependent. Table 4-3 presents the
4-8
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temperatures at which the solubilities and vapor pressures used to
calculate the Henry's Lav Constants vere measured. For the purpose of
calculating screening levels, a sever atmosphere temperature of
approximately 25°C is assumed.
Steady state system - The collection system at the point of each Ill's
discharge is presumed to constitute a steady state system in which
(1) thermodynamic equilibrium between the water and vapor phases is
established immediately upon discharge, and (2) pollutant concen-
trations in the vapor and water phases do not change with time. In
reality, instantaneous attainment of equilibrium is only an approxi-
mation as sufficient time may not exist at the point of discharge for
equilibrium to be established between the liquid and vapor phases. In
addition, constant air flow through the sever that tends to lover
concentrations of pollutants in the vapor phase below equilibrium
values, and fluctuations in pollutant discharge levels vill upset both
steady state and equilibrium conditions.
Solubility effects caused by organic compounds (e.g., oil and grease)
and dissolved salts - Solubility values reported in the literature,
and used to calculate Henry's Law Constants, assume distilled,
deionized water as a solvent. In practice, however, various organic
compounds are generally present in the IU wastestream and/or in the
collection system wastewater at the point of discharge. The presence
of these compounds will generally tend to increase pollutant solubi-
lities above their corresponding pure aqueous solubilities. In
addition, pollutant solubilities may be lowered below pure aqueous
solubilities by the presence of significant concentrations of dis-
solved salts. In either case, changing the solubility of the pol-
lutant of concern affects the value of the Henry's Law Constant;
however, the influence of organic compounds and/or dissolved salts on
pollutant solubility, and consequently, on the Henry's Law Constant,
is not readily quantified. Therefore, variations in pollutant
solubility due to the presence of organic compounds and/or dissolved
salts in the wastestream are not considered.
Screening levels should be used to identify flammable/explosive
pollutants for control. In developing local limits based on pollutant
flammability/explosivity, careful consideration should be given to the above
assumptions and site specific data should be relied upon where available.
4.1.2 Corrosion
The specific prohibitions of the General Pretreatment Regulations (AO CFR
403.5(B)(2)) forbid IUs from discharging "pollutants which will cause
corrosive structural damage to the POTU, but in no case discharges with pH
lover than 5.0, unless the works is specifically designed to accommodate such
4-9
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discharges." Thus in order to protect POTVs from corrosive discharges, the
specific prohibitions explicitly forbid IU discharges with pH less than 5,
unless the POTV is specially designed to accept such wastes. In addition to
implementing the specific prohibitions against discharges with low pH, POTVs
should consider developing local limits to restrict discharges that are
corrosive because they have a high pH and/or high concentrations of one or
more of the following substances:
Sulfides
Chlorides
Sulfates
Nitrates
Chlorine
Dissolved salts
Suspended solids
Organic compounds.
The concerns associated with each of these properties/constituents, as
well as options for local limits development, are identified below. The
information on corrosion presented below is based on reviews by DeBarry, et
al. (47); Patterson (48); and Singley, et al. (49).*
Upper pH Discharge Limits
Although their corrosivity has not been completely explored, substances
with high pH are capable of producing a variety of undesired effects on sewer
system materials. Researchers have established that as the pH of solutions
increase beyond 13, there is generally a slight increase in the corrosion
rates of iron and steel. The lower corrosion rates in basic waters as
compared to acidic waters is due to the fact that basic waters support the
formation of inorganic films and precipitates that act as coatings to protect
the walls of pipes transporting water. The effects of pH on other
construction materials used in sewers, such as asbestos-cement, concrete,
clay, and PVC; and materials used in linings, joints, and gaskets, such as
zinc, bituminous materials, epoxy resins, paints, polyurethane, cement mortar,
and neoprene, are not completely understood. Concrete, asbestos-cement, and
4-10
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cement mortar are known to be strongly affected by acidic solutions that
dissolve calcium compounds. Concrete and cement are also somevhat susceptible
to dissolution in low-calcium neutral and basic solutions. Although
important, the role of pH in increasing the corrosive properties of certain
chemicals is not well known.
Should the POTV identify corrosion damage attributable to high pH
discharges, an upper pH local limit should be established and enforced. There
are many techniques by which the POTV can establish an upper pH local limit.
POTWs can perform field inspections of Ills and monitor IU discharges in
support of developing IU-specific upper pH local limits. In addition, POTWs
may wish to rely on the available literature to support data gathered by field
inspections and/or through corrosivity testing. Another method for
establishing an upper pH limit is to perform corrosivity tests on the various
construction materials to which wastewaters are exposed in the collection
system and treatment works. Such tests would allow the POTV to develop a
local limit for upper pH that is specific to the POTV's own particular
structural materials. The drawback of this procedure is that it requires
considerable funding in addition to the investment of time.
Other Pollutants of Concern
POTVs should consider developing local limits for any additional
pollutants that have the potential for contributing to corrosive damage to
sewers, including:
Sulfides, discharged either directly into the sewer system, or
generated through the reduction of sulfates by anaerobic bacteria, are
a major cause of corrosion. In neutral and basic waters, the
protective films and precipitates that form on the walls of pipes are
susceptible to deterioration and replacement by metal sulfides. In
addition, metal sulfides may also corrode iron directly, and dissolved
hydrogen sulfide (HS~ and S" ) may be associated with increased
corrosion. Above the water line, hydrogen sulfide contained in
condensed water vapor is biologically oxidized to sulfuric acid.
Sulfuric acid is known to corrode iron, steel, concrete, asbestos-
cement, and cement mortar.
Chloride is known to adversely affect the protective inorganic films
and precipitates that form on sewer walls (e.g., iron oxide).
Chloride not only can decay and penetrate the coatings, but can
prevent them from developing by forming more soluble metal chlorides
instead.
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Chlorine acts to increase the corrosion of iron and steel by aiding in
the formation of hydrochloric and hypochlorous acids that decrease the
pH of the discharge.
Nitrates contribute to iron and steel corrosion through preferential
reduction at cathodic areas.
Suspended particles in discharges act to erode and abrade sewer vails.
Solvent properties of organic compounds promote dissolution of
rubber/plastic linings, gaskets, etc.
Dissolved salts, particularly sulfates, can cause corrosion of
concrete, asbestos-cement, and cement mortar. The electrolytic action
of dissolved salts promotes the corrosion of metals.
4.1.3 Flow Obstruction
The specific discharge prohibitions of the General Pretreatment
Regulations (40 CFR 403.5(b)(3)) forbid Ills from discharging "solid or viscous
pollutants in amounts which will cause obstruction to the flow in the POTV
resulting in interference." In order to implement this prohibition, POTVs
should conduct periodic inspections of the collection system and of IU
discharges to ensure that wastewater flows are not impeded. POTVs should
require IUs to clean their grease traps on a frequent basis. As a reasonable
control measure, POTVs might require IU discharge solids to be small enough to
pass through a three-eighths inch mesh screen.
4.1.4 Temperature
The specific discharge prohibitions forbid IUs from discharging "heat in
amounts which will inhibit biological activity in the POTV resulting in
Interference, but in no case heat in such quantities that the temperature at
the POTV Treatment Plant exceeds 40°C (104°F)," unless other temperature
limits are approved. Collection system dilution of heated industrial waste-
waters usually ensures compliance with this prohibition. Generally, of more
immediate concern to the POTV is the temperature of the IU discharge at the
IU's sewer connection. Heated industrial wastewaters pose a hazard to POTV
workers who must enter the sewer at manholes immediately downstream of the
IU's discharge point. Should POTV workers encounter an IU discharge which is
hot enough to restrict or prevent sewer entry, the POTV should require the IU
to reduce the temperature of its discharge. To this end, the POV can require
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the IU to institute appropriate wastewater discharge management practices
(e.g., holding the wastewater long enough for it to cool) and/or to install
requisite temperature control technologies (e.g., heat exchange equipment).
The POTW should be aware that exothermic chemical reactions between the
IU discharge and the receiving sewage may result in elevated temperatures. In
addition, heats of dilution and solution accompanying the discharge of certain
concentrated wastes can also cause temperature increases. The POTV may need
to investigate these sources of heat and develop local limits that restrict
the substances causing elevated temperatures.
4.2 WORKER HEALTH AND SAFETY
Industrial discharges to sewers may create conditions that endanger the
health and safety of POTV workers. Two major hazards encountered by POTW
workers are exposure to toxic fumes and injury from explosion or fire. Local
limits based on fire and explosion concerns have been discussed in Section
4.1.1. The following section will discuss local limits based on fume
toxicity. It should be understood that the setting of local limits based on
fume toxicity is not a substitute for good safety precautions. Section 4.2.4
provides a general discussion of safety precautions in order to emphasize
their importance. Development of local limits to prevent specific problems is
a supplement to a good safety program.
The following two procedures for establishing fume toxic pollutant
discharge limits and source control requirements are discussed in this
section:
Headspace monitoring
Industrial user management practice plans.
A screening technique for identifying potential problem discharges is
also presented.
4.2.1 Headspace Monitoring
There are a variety of methods for setting local limits to control the
discharge of fume toxic pollutants to POTUs. Vapor phase monitoring of the
headspace in the sewer or in an equilibrated wastewater sample is a direct
4-13
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approach for quantifying specific substances in order to determine if there is
a danger to worker health and safety. As discussed in Section 4.1.1.2, one
innovative approach to local limits for both flammable/explosive and fume
toxic pollutants has been developed and implemented by the Cincinnati
Metropolitan Sanitary District (MSD). Control of fume toxic discharges by the
MSD's local limits approach is further detailed in this section.
As described in Section 4.1.1.2, the MSD has established a volatile
organic pollutant local limit, based on the sample headspace monitoring
technique presented in Appendix J. The local limit consists of a 300 ppm
hexane equivalent limit on total volatile organics in headspace gases
accumulated over an equilibrated wastewater sample (See Appendix J for the
detailed analytical procedure). The 300 ppm hexane equivalent limit was
developed by MSD in consultation with the National Institute for Occupational
Safety and Health (NIOSH) and was designed to provide POTV workers exposed to
sewer atmospheres at least minimal protection from pollutant fume toxicity.
NIOSH and MSD concluded that below the 300 ppm hexane equivalent limit,
carbon filters would, in general, provide POTV workers with adequate
protection [55]. EPA's Technology Assessment Branch, Wastewater Research
Division, reviewed NI0SH/MSD documentation and observed that the limit is not
chemical-specific, and therefore does not ensure that Occupational Safety and
Health Administration (0SHA) permissible exposure levels (PELs) of individual
volatile organics will be met in sewer atmospheres [55). The EPA review,
however, also concluded that the 300 ppm hexane equivalent limit should
prevent concentrations of volatile organics from exceeding the Immediately
Dangerous to Life and Health (IDLH) level in sewer atmospheres and should
essentially eliminate public exposure to dangerous levels of volatile organics
through sewer air exchanges [55].
The EPA review of the MSD's 300 ppm hexane equivalent limit concluded
with the caution that implementation of this volatile organic limit, or for
that matter, any volatile organic limit, will not alter the fact that toxic
vapors from spills, hydrogen sulfide and methane gas generation in sewers, and
vapor purging of oxygen from sewers represent significant health hazards-
Sewer workers should not be allowed in severs or confined spaces without
4-14
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portable explosimeters and appropriate breathing devices [55]. Section 4.2.4
discusses these POTV worker safety issues in more detail.
4.2.2 Industrial User Management Practice Plans
In addition to establishing a numeric local limit on the discharge of
fume toxic pollutants, the POTV can often require Ills to submit management
practice plans. These plans document III procedures for handling process
chemicals and controlling chemical spills. The documented procedures also
detail IU measures taken to prevent toxic pollutant discharges to the POTV.
Ill implementation of proper chemical handling and spill control procedures
alone can often effectively eliminate the possibility of toxic pollutant
discharges, thereby obviating the need for further control measures. Chapter
5 discusses industrial user management practice plans in more detail.
4.2.3 Screening Technique for Identifying Fume Toxic Pollutant Discharges
In order to identify IU discharges which could potentially generate fume
toxic conditions in sewer atmospheres, an IU discharge screening procedure
should be established. This screening procedure would identify fume toxic
pollutant discharges warranting control through the imposition of local limits
and/or other IU requirements.
One such technique for identifying fume toxic pollutant discharges
entails 1) conversion of fume toxicity criteria into corresponding IU dis-
charge screening levels, and 2) comparison of these screening levels with
actual IU discharge levels. Exceedances may warrant further investigation by
the POTV, perhaps involving the control measures discussed in Sections 4.2.1
and 4.2.2 above.
The American Conference of Governmental Industrial Hygienists (ACGIH)
threshold limit value-time weighted averages (TLV-TVAs) serve as a measure of
fume toxicity from which IU discharge screening levels can be calculated. The
ACGIH TLV-TVA fume toxicity levels are the vapor phase concentrations of
volatile organic compounds to which nearly all workers may be repeatedly
exposed, over an eight hour workday and a 40-hour work week, without adverse
effect. In general, POTV workers are not exposed for extended period of time
to sewer atmospheres contaminated with volatile compounds, and the use of
TLV-TVA concentrations as a basis for developing IU discharge screening levels
can be considered a conservative practice.
4-15
-------
The calculation of screening levels that are based on fume toxicity
involves the following four steps:
1. Determine the ACGIH TLV-TVA concentration of the pollutant of concern
ACGIH TLV-TVA concentrations (mg/m ) for several representative
organic pollutants from the Appendix G list are presented in the
second column of Table 4-4. Appendix G, as well as the ACGIH
document referenced in Table 4-4, present ACGIH TLV-TVA data for many
additional pollutants.
2. Determine the Henry's Law Constant for the pollutant of concern.
Table 4-3 presents the Henry's Law Constants for several volatile
organics.
3. Convert the Henry's Law Constant to the appropriate units. In order
to calculate screening levels based on ACGIH TLV-TVA concentrations,
the Henry's Law Constant must be expressed in terms of (mg/m )/
(mg/L). The following equation should b| used to convert the Henry's
Law Constant expressed in units of atm m /mol to the equivalent
constant expressed in (mg/m )/(mg/L): ,
1 x 10s
Hc = Ha x (mg/m3 )/(mg/L)
(R)(T)
where: Hc = Henry's Law Constant, (mg/m3)/(mg/L)
HA = Henry's Law Constant, (atm m3/mol)
R = Ideal gas constant, 0.08206 (atm L/mol K)
T = Temperature corresponding to vapor pressure* used to
derive HA, K (See Table 4-3)
Henry's Law Constants expressed in (mg/m3)/(mg/L) are presented for
several volatile organics in the third column of Table 4-4.
4. Calculate the IU discharge screening level from the Henry's Law
expression:
CLVL
^VAP
H
where
CLVL = Discharge screening level, mg/L
Cvap = ACGIH TLV"TVA' mg/m3
H = Henry's Law Constant, (mg/m )/(mg/L)
*Assume T = 298.15 K if data are not available.
4-16
-------
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, see assumptions delineated
in Section 4.1.1.5) and does not take into account dilution of IU
wastewater within the collection system.
Screening levels should be used to identify fume toxic pollutants for
control. In developing local limits to address fume toxicity, the techniques
presented in Section 4.2.1 and 4.2.2 may be useful. As with chemical specific
limits for flammable/explosive pollutants, careful consideration should be
given to the assumptions delineated in Section 4.1.1.5 and site specific data
should be relied upon where available.
The fourth column of Table 4-4 presents ACGIH TLV-TVA-based screening
levels calculated for several volatile organics. Several observations can be
made from the data:
Screening levels based on TLV-TWA fume toxicity data are more
stringent than screening levels based on explosivity (LEL) data
(Tables 4-2 and 4-4).
The only screening level presented in Table 4-4 which exceeds 5 mg/L
is the screening level for methyl ethyl ketone (249 mg/L). The
particularly high screening level for this pollutant is at least in
part due to its low Henry's Law Constant (2.37 mg/m / mg/L), which
indicates that methyl ethyl ketone is not as volatile as the other
compounds listed in Table 4-4.
The lowest screening level presented in Table 4-4 is for hexachloro-
1,3-butadiene (0.2 ug/L). This stringent screening level is attri-
butable to the fact that hexachloro-1,3-butadiene is highly fume toxic
(its TLV-TWA of 0.24 mg/m3 is the lowest presented in Table 4-4), and
also highly volatile (Henry's Law Constant = 1064 mg/m /mg/L).
Screening levels calculated from ACGIH TLV-TWA data address only the
toxicities of individual compounds. The screening levels presented in Table
4-4 do not address the generation of toxic concentrations of gases that are
produced from the mixture of chemicals in the vastestream. The following
procedure allows the POTW to predict the potential vapor toxicity associated
with the discharge of a mixture of volatile organic compounds:
4-17
-------
1. Analyze the industrial user's wastewater discharge for volatile
organics. The following are hypothetical monitoring data:
Although these discharge levels are all below the corresponding
screening levels presented in Table 4-4, the POTV should determine
whether the simultaneous discharge of the five pollutants could
result in a fume toxic mixture within the sewer.
2. Use Henry's Law,
Pollutant
Discharge
Level, mg/L
Benzene
Toluene
Chlorobenzene
1,2-Dichlorobenzene
1,4-Dichlorobenzene
0.1
0.9
2.2
3.57
3.39
C,
VAPOR
= H x C,
DISCHARGE
where
C,
H
VAPOR
= Vapor phase concentration, mg/m3
= Henry's Law Constant, mg/m3/mg/L
= Discharge level, mg/L,
to calculate the equilibrium vapor phase concentration of each
pollutant:
Pollutant
Discharge
Level, mg/L
Henry's
Law Constant,
mg/m /mg/L
Equilibrium
Vapor Phase
Concentration, mg/m
Benzene
Toluene
Chlorobenzene
1,2-Dichlorobenzene
1,4-Dichlorobenzene
0.1
0.9
2.2
3.57
3.39
225
277
149
80.2
127
22.5
249.3
327.8
286.3
430.5
4-18
-------
3. Express the equilibrium vapor phase concentrations (above) as
fractions of the corresponding TLV-TVAs:
Equilibrium
Vapor Phase
TLV-TVA
Fraction of
Pollutant
Concentration, mg/m
mg/m
TLV-TVA
Benzene
22.5
30
0.75
Toluene
249.3
375
0.66
Chlorobenzene
327.8
350
0.94
Chlorobenzene
327.8
350
0.94
1,2-Dichlorobenzene
286.3
300
0.95
1,4-dichlorobenzene
430.5
450
0.96
4.26
4. Sum the fractions of the TLV-TWAs. In the example above, the sum of
the TLV-TVA fractions equals 4.26.
If the compounds in question are assumed to possess additive fume
toxicities vhen mixed, then if the sum of the TLV-TVA fractions is
greater than 1.00, a potentially fume toxic condition exists.
5. If the sum of the TLV-TVA 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 fume toxic condition.
Using the example values:
1 -
4.26 J
x 100 = 77% reduction of the discharge of all five
pollutants to alleviate the potentially fume
toxic condition, (assuming additive toxicities
and the applicability of the Henry's Lav
Constants)
4.2.4 POTW Worker Safety
Local limits based upon explosivity and/or fume toxicity do not obviate
the need for P0TV safety programs and the proper use of safety procedures by
POTV workers when entering sewer manholes. Even if reasonably sound local
limits and/or source controls have been instituted, these controls/limits may
occasionally be violated, either accidentally or intentionally. A major
discharge violation, even if only for a short duration, could result in
harmful pollutant levels in sever atmospheres. Local limits and source
controls therefore, are merely precautionary; no local limit could ever
substitute for sound safety precautions and the use of sound judgment by field
personnel before manhole entry.
4-19
-------
In August, 1981, NIOSH prepared a Health Hazard Evaluation Report (BETA
81-207-945) for the Cincinnati Metropolitan Sanitary District (MSD) [56]. The
following recommendations concerning POTV worker safety were presented at the
conclusion of this report [56]:
Overall:
Protection of sewer workers from incidents involves vigorous
enforcement of wastewater regulations, adequate industrial hygiene
measurement of potentially dangerous sewer atmospheres prior to sewer
entry, provision of proper sewer ventilation, proper use of adequate
personal protection equipment while working in or near sewers, and
adequate medical surveillance to enable early detection of illness
associated with exposure to toxic chemicals in the sewer environment.
Instrumentation and Training:
Before entering the sewers, POTV personnel should test the atmosphere
with rugged, portable, direct-reading instruments such as
explosimeters, oxygen detectors, and supplemented if appropriate by
organic vapor detectors, and colorimetric indicator tubes.
Training of POTV personnel in the use of direct-reading instruments
should be conducted before POTV personnel use equipment at a work
site.
Respiratory
Because of the chemical composition of the sewer's atmosphere and its
potential to change rapidly and without notice, particularly in
industrial sections which receive both commercial and industrial
sewage, the underground personnel should use open-circuit air-line
supplied respirators when direct-reading instruments indicate the
presence of toxic substances in concentrations immediately dangerous
to health or life. At lower concentrations, NIOSH-approved full- or
half-face chemical cartridge respirators should be worn by personnel
entering industrial sewers.
A respiratory protection program should be established and enforced by
POTV management.
Engineering Controls:
Forced-air ventilation should be used whenever possible when working
in sewers, especially industrial sewers.
The jet exhaust venturi blower (air horn) connected to the end of the
compressor air hose (with organic filter) and used to aspirate fresh
air into the workspace should be kept at street level. The air intake
should be away from automobile or diesel exhaust emissions. A
4-20
-------
flexible elephant duct should be attached to the blower and extended
to the work area to bring fresh air from the surface.
Medical Surveillance:
A system should be developed for reporting symptoms following exposure
to chemical contaminants in sewers. A log of such reports should be
maintained. In combination with results of such medical tests as
deemed necessary, such a log will enable the POTU and its medical
consultant to determine any adverse trends in exposure incidents.
Safety
Each underground worker should be provided with arm wristlets, safety
lines, and harnesses for rapid removal from the sewer.
Other:
The City Fire Department's Emergency Response Team should be alerted
whenever POTV workers are entering a sewer environment that may be
hazardous to the worker.
Sewer permits for industrial users should regulate the discharge of
potentially volatile compounds which may be present in sewer vapor
spaces.
The above recommendations should be implemented as an integral part of
every POTV's worker health and safety program.
4-21
-------
TABLE 4-1. CLOSED CUP FLASHPOINTS OF SPECIFIC ORGANIC CHEMICALS
Compound Flashpoint, "F
Gasoline -50
Hexane -7
Acetone 0
Benzene 12
Ethyl alcohol 55
Methyl isobutyl ketone 73
Isobutyl alcohol 82
Acetic acid 104
Furfural 140
Benzaldehyde 148
Naphthalene 174
Propylene glycol 210
Stearic acid 385
Source: Hazards Evaluation and Risk Control Services Bulletin
HE-120A, compiled and printed by the Hercules
Corporation.
The Merck Index, Merck and Company, Inc., 1976.
Rahvay, NJ. Ninth Edition.
4-22
-------
TABLE 4-2.
DISCHARGE
SCREENING LEVELS
BASED ON EXPL0SIVITY
.impound
LEL, X
CVAp (mol/m3)
* H1 (mol/m
3)/(mg/L)
CL V L ("'S71
Acryloni trile
3.0
(31)
1.23
6.83
X
10~5
17954
Benzene
1.4
(31)
0.57
2.88
X
l"3
199
Bromomethane
10.0
(3)
4.09
8.62
X
10"2
47
Carbon disulfide
1.0
(31)
0.41
6.44
X
10~3
63
Chlorobenzene
1.3
(31)
0.53
1.32
X
10"3
403
Chloroethane
3.8
(8)
1.55
9.54
X
10"2
16
Chloromethane
8.1
(5)
3.31
3.08
X
10"1
11
1,2-Dichlorobenzene
2.2
(31)
0.90
5.46
X
10"4
1647
1,3-Dichlorobenzene
2.2
(31)
0.90
1.00
X
10"3
899
1,4-Dichlorobenzene
2.2
(31)
0.90
8.62
X
10"4
1043
1,1-Dichloroethane
5.6
(3)
2.29
1.79
X
10"3
1279
trans-1,2-Dichloroethylene
9.7
(31)
3.97
2.87
X
10"2
138
1,2-Dichloropropane
3.4
(8)
1.39
8.50
X
10"4
1635
1,3-Dichloropropene
5.3
(50)
2.17
4.98
X
10"4
4357
Ethyl benzene
1.0
(31)
0.41
2.58
X
10"3
158
"hylene dichloride
6.2
(3)
2.53
3.84
X
10"4
6589
.ormaldehyde
7.0
(50)
2.86
6.94
X
10"4
4121
Methylene Chloride
14.0
(50)
5.72
9.93
X
10"4
5760
Methyl Ethyl Ketone
2.0
(31)
0.82
3.29
X
10"5
24848
Toluene
1.27 (31)
0.52
3.01
X
10"3
173
1,2,4-Trichlorobenzene
2.5
(50)
1.02
5.18
X
10"4
1969
1,1,1-Trichloroethane
7.5
(50)
3.07
9.19
X
10"3
334
Trichloroethylene
8.0
(50)
3.27
2.88
X
10"3
1135
Vinyl chloride
3.6
(31)
1.47
5.32
X
10"2
28
Vinylidene chloride
6.5
(50)
2.66
8.01
X
10"2
33
*Vapor phase concentration calculated from LEL, assuming temperature = 25°C.
henry's Law Constants (mol/m3)/(mg/L) taken from Table 4-3.
4-23
-------
TABLE 4-3. HENRY'S LAW CONSTANTS EXPRESSED IN ALTERNATE UNITS
Henry's Lav Constant Temperature, °C
Compound
atm m3
mol
mol/m3
mg/L
, 3
mg/m
mg/L
Vapor
Pressure
Solubili ty
Acenaphthylene
1.45
X
10"3
33)
3.96
X
10"4
60.3
20
25
Acryloni trile
8.80
X
10" 5
33)
6.83
X
10"5
3.62
22.8
25
Anthracene
1.25
X
10"3
33)
2.87
X
10"4
51.1
25
25
Benzene
5.50
X
10"3
33)
2.88
X
10"3
225
25
25
Bromomethane
1.97
X
10"1
12)
8.62
X
10"2
8189
20
20
Carbon disulfide
1.20
X
10"2
19)
6.44
X
10"3*
490*
Carbon tetrachloride
2.30
X
10"2
33)
6.21
X
10*3
956
20
20
Chlorobenzene
3.58
X
10"3
33)
1.32
X
10'3
149
20
25
Chloroethane
1.48
X
10"1
12)
9.54
X
10"2
6152
20
20
Chloroform
2.88
X
10" 3
33)
1.00
X
10"3
120
20
20
Chlorome thane
3.80
X
10"1
19)
3.08
X
10"1*
15532*
1,2-Dichlorobenzene
1.93
X
10"3
33)(12)
5.46
X
10" 4
80.2
20
20
1,3-Dichlorobenzene
3.61
X
10"3
33)(12)
1.00
X
10"3
148
25
25
1,4-Dichlorobenzene
3.10
X
10"3
33)(12)
8.62
X
10" 4
127
25
25
Di chlorodi fluorome thane
2.98
X
10° (
2)
1.01
X
10°
121801
25
25
1,1-Dichloroethane
4.26
X
10"3
12)
1.79
X
10"3
177
20
20
trans-1,2-Dichloroethylene
6.70
X
10"2
12)
2.87
X
10" 2
2785
20
20
1,2-Dichloropropane
2.31
X
10"3
12)
8.50
X
10"4
96.0
20
20
1,3-Dichloropropene
1.33
X
10"3
12)
4.98
X
10"4
55.3
20
25
Ethyl benzene
6.60
X
10"3
33)(12)
2.58
X
10"3
274
20
20
Ethylene dichloride
9.14
X
10"4
33)
3.84
X
10"4
38.0
20
20
Formaldehyde
5.10
X
10"4
(54)
6.94
X
10"4 *
20.8
-------
TABLE 4-3. HENRY'S LAW CONSTANTS EXPRESSED IN ALTERNATE UNITS (Continued)
Henry's Lav Constant Temperature, °C
atm
3
m
mol/m3
mg/m3
Vapor
Compound
mol
mg/L
mg/L
Pressure
Solubili ty
Heptachlor
4.00
X
10"
(33)
4.38
X
10"
163
25
25
Hexachloro-1,3-butadiene
2.56
X
10"
(33)
4.08
X
10"
1064
20
20
Hexachloroethane
2.49
X
10"
(33)
4.37
X
10"
104
20
22
Methyl Ethyl Ketone
5.80
X
10"
(19)
3.29
X
10"
*
2.37*
Methylene chloride
2.03
X
10"
(33)
9.93
X
10"
84.4
20
25
Pentachloroe thane
2.17
X
10"
(19)
4.38
X
10"
*
88.7*
1,1,1,2-Tetrachloroe thane
1.10
X
10"
(33)
2.68
X
10"
k
450*
Tetrachloroethylene
1.53
X
10"
(12)
3.83
X
10"
636
20
20
Toluene
6.66
X
10"
(33)
3.01
X
10"
111
20
25
1,2,4-Trichlorobenzene
2.30
X
10"
(12)
5.18
X
10"
94.0
25
25
1,1,1-Trichloroethane
3.00
X
10"
(33)
9.19
X
10"
1226
25
25
Trichloroethylene
9.10
X
10"
(33)
2.88
X
10"
378
20
20
Trichlorofluoromethane
1.10
X
10"
(12)
3.33
X
10"
4573
20
20
Vinyl chloride
8.14
X
10"
(33)(12)
5.32
X
10"
3327
25
25
Vinylidene chloride
1.90
X
10"
(12)
8.01
X
10"
7766
25
20
Aroclor 1242
1.98
X
10"
(12)
3.14
X
10"
itic
80.9
25
25
Aroclor 1248
3.60
X
10"
(12)
5.04
X
10"
**
147
25
25
Aroclor 1254
2.60
X
10"
(12)
3.26
X
10"
106
25
25
Aroclor 1260
7.40
X
10"
(12)
8.38
X
10"
30246
25
25
*A temperature of 25°C was
assumed
in
Henry's
Law calculat
ons
**The molecular weights of the following compounds were used to represent the molecular weights
of Aroclor mixtures in Henry's Law calculations:
Aroclor 1242 Trichlorobiphenyl
Aroclor 1248 Tetrachlorobiphenyl
Aroclor 1254 Pentachlorobiphenyl
Aroclor 1260 Hexachlorobiphenyl
-------
TABLE 4-4. DISCHARGE SCREENING LEVELS BASED UPON FUME TOXICITY
Compound
Acryloni trile
Benzene
Bromomethane
Carbon disulfide
Carbon tetrachloride
Chlorobenzene
Chloroethane
Chloroform
Chloromethane
1,2-Dichlorobenzene
1,4-Dichlorobenzene
Dichlorodi fluoromethane
1.1-Dichloroethane
trans-1,2-Dichloroethylene
1.2-Dichloropropane
1.3-Dichloropropene
Ethyl benzene
Ethylene dichloride
Formaldehyde
Heptachlor
Hexachloro-1,3-butadiene
Hexachloroe thane
Methyl ethyl ketone
Methylene chloride
Tetrachloroethylene
Toluene
1,2,4-Trichlorobenzene
1,1,1-Trichloroethane
Trichloroethylene
Trichlorofluoromethane
Vinyl chloride
ACGIH
TLVjTWA, Henry's Law Screening
mg/m (30) Constant,* mg/m /mg/L Level, mg/L
4.5 3.62 1.24
30.0 225 0.13
20.0 8189 0.002
30.0 490 0.06
30.0 956 0.03
350.0 149 2.35
2600.0 6152 0.42
50.0 120 0.42
105.0 15532 0.007
300.0 80.2 3.74
450.0 127 3.54
4950.0 121801 0.04
810.0 177 4.58
790.0 2785 0.28
350.0 96.0 3.65
5.0 55.3 0.09
435.0 274 1.59
40.0 38.0 1.05
1.5 20.8 0.07
0.5 163 0.003
0.24 1064 0.0002
100.0 104 0.96
590.0 2.37 249
350.0 84.4 4.15
335.0 636 0.53
375.0 277 1.35
40.0 94.0 0.43
1900.0 1226 1.55
270.0 378 0.71
5600.0 4573 1.22
10.0 3327 0.003
4-26
-------
TABLE 4-4. DISCHARGE SCREENING LEVELS BASED UPON FUME TOXICITY (Continued)
ACGIH
TLVjTVA, Henry's Law Screening
Compound mg/m (30) Constant,* mg/m3/mg/L Level, mg/L
Vinylidene chloride 20.0 7766 0.003
Aroclor 1242 1.0 80.9 0.01
Aroclor 1254 0.5 106 0.005
*Henry's Lav Constant (mg/m /mg/L) taken from Table 4-3.
4-27
-------
5. INDUSTRIAL USER MANAGEMENT PRACTICES
5.1 INTRODUCTION
The development and implementation of numeric local limits is not always
the only appropriate or practical method for preventing pollutant pass through
and interference, or for protecting POTV worker health and safety. Control of
chemical spills and slug discharges to the POTV through formal chemical or
waste management plans can go a long vay toward preventing problems. A local
requirement for an IU to develop and submit such a plan can be considered as a
type of narrative local limit and can be a useful supplement to numeric
limi ts.
The basic philosophy of instituting management practices is to minimize
the discharge of toxic or hazardous pollutants to the sewer, or at least to
reduce the impact of toxic/hazardous pollutant discharges by avoiding short-
term, high concentration discharges. Management practice plans generally are
developed to prevent or control the discharge of hazardous or toxic materials,
such as acids, solvents, paints, oils, fuels and explosives by means of
appropriate handling procedures, possibly in addition to pretreatment. Slug
discharges of process wastewater (including high BOD/COD wastes) can also be
effectively controlled through the use of management practices.
In the NPDES permitting program for direct dischargers, industries can be
required under 40 CFR Part 125, Subpart K to implement best management
practices (BMPs) to minimize the discharge of toxicants to surface waters.
These plans are meant to address:
Toxic and hazardous chemical spills and leaks
Plant site run-off
Sludge and waste disposal
Drainage from material storage areas
Other "good housekeeping" practices.
While direct discharger BMPs address only activities which are ancillary to
manufacturing or treatment processes, IU management practices under a local
pretreatment program can also include:
5-1
-------
Solvent management plans
Batch discharge policies
Waste recycling
Waste minimization.
The first step a POTW must take in implementing its program is to be
certain that the POTW has the requisite legal authority. This involves
ensuring that proper language regarding IU management practices are contained
in the sewer use ordinance (at a minimum) and in IU permits. The sewer use
ordinances or regulations of most POTWs may already include provisions for
requiring Ills to develop management practice plans.
When evaluating the need for IU management plans, POTWs may follow the
following steps:
Evaluation of the potential for toxic and hazardous chemicals onsite
to reach the sewer system
Assessing the adequacy of any industry management plans and practices
already in place, and requiring revisions to these as necessary.
1. Evaluation of the Potential for Toxic and Hazardous Chemicals Onsite to
Reach the Sever System. The primary concern on the part of the POTV when
evaluating the adequacy of IU management practices is the likelihood of slugs/
spills of chemicals reaching the sever system. Inspectors need to focus on:
(1) the types of and quantities of chemicals that are handled (e.g., trans-
ferred), stored, or disposed onsite; and (2) the location(s) of all chemical
handling, storage and disposal activities vith respect to sever access. The
chemicals managed in areas of highest risk of being discharged to the severs
(through spills, slug loading, or accidents) should be of the highest priority
to be addressed in management plans.
2. Assessing the Adequacy of Existing Management Plans and Practices. POTU
officials should carefully evaluate any existing industry management plans.
Receiving particular scrutiny should be:
The practices that are proposed (and whether they are currently being
followed)
5-2
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Whether the plan is reflective of current operations at the industry
Whether the plan vas designed to prevent discharges to the severs
Whether plant personnel are required to follow the plan
The familiarity of personnel vith the plan
Any conditions that must be met before a response/corrective action
can be taken
Whether all toxic chemicals managed in areas with access to severs are
addressed.
If deficiencies are found in the existing plans, the IU should be required to
correct them before submitting a revised plan to the POTW for approval-
Further details of recommended plan specifics are discussed later in this
section.
The following sections of this chapter outline the elements of three
types of industry management practice plans, chemical management plans, spill
contingency, and best management practices plans. POTWs should be aware that
hybrids of the plans presented may be appropriate for a particular situation
and that some overlap of management practice requirements exists. Key to each
of these plans is the continued training of staff and proper implementation.
5.2 CHEMICAL MANAGEMENT PLANS
Chemical management plans differ from the other two types of management
plans introduced above because they target specific chemicals or groups of
chemicals that are considered to be of concern. One example of a chemical
management plan that is widespread is the solvent management plan required of
metal finishers by federal categorical standards.
POTWs may vish to pay special attention to certain groups of chemicals
that have historically caused management problems. Examples of such chemical
groups are:
Strong acids (e.g., hydrochloric acid, sulfuric acid, nitric acid, and
chromic acid)
Strong bases (e.g., caustic soda, lye, ammonia, lime, etc.)
5-3
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Noxious/fuming chemicals (e.g., phosphorus pentachloride, hydrofluoric
acid, benzene, chloroform)
Flammable chemicals (e.g., acetone, naptha, hexane, cyclohexane)
Explosive chemicals (e.g., nitroglycerine, metallic sodium, picric acid,
and lead azide)
Oxidants (e.g., chlorine dioxide, phosphorus pentoxide, potassium
permanganate, sodium chlorate)
Reductants (e.g., sodium borohydride, phosphine, methyl hydrazine)
Oils and fuels (e.g., diesel oil, gasoline, bunker fuel oil)
Toxic wastes (e.g., pesticides)
Solvents
Radioactive materials
Foaming Materials (e.g., surfactants).
It is impossible to present an all encompassing list of chemicals that
might suitably be addressed under chemical management plans as the needs and
concerns of any specific POTV and its industries will be different. However,
much attention has recently been paid to one particular group of chemicals,
the frequently used solvents. Table 5-1 presents a list of frequently used
solvents and their regulatory status. In presenting this table, it is not the
intention to suggest that the solvents on this list will always be a problem.
Rather, this list is a recognition of the fact that solvents are ubiquitous to
sewer systems and can make up a large portion of the usually uncontrolled
organic loadings to treatment plants. Concerns regarding these chemicals may
be less familiar to POTV personnel than concerns regarding other chemicals
such as acids and bases.
As part of the assessment of an industry's chemical management plan, the
POTV must first determine the following: the nature of chemical usage at the
IU, chemical handling practices, specific process streams containing the
chemical, and locations where the chemicals might (intentionally or uninten-
tionally) enter the sewers. An analysis of the chemical's concentration at
potential as well as known release points should be obtained as part of this
5-4
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data gathering effort. These data should be gathered through onsite inspec-
tions whenever possible. Once this basic information is compiled, its
accuracy should be verified with the IU and should subsequently provide the
basis for assessing the need for, and adequacy of, chemical management plans
submitted by the industry. Elements of the industry's chemical management
plan should address each of the potential release points. Whenever possible,
the industry should be provided with specific language indicating the accept-
able levels of the chemical in the sewer so that a clear yardstick is estab-
lished against which the success or failure of the management plan can be
measured. An example of this is again provided by the metal finishing
industry's solvent management plans which attempt to achieve a total toxic
organic (TTO) pollutant limit of 2.13 mg/1.
Examples of plan components that would target specific release points
are: prevent access through floor drains to sewers in areas of possible
chemical spillage; the installation of sumps in floor drains providing a
capacity that exceeds the largest projected potential spill volume by a safety
margin of perhaps 10 percent; and the education of plant workers handling the
chemicals of concern in areas with access to sewers.
POTW staff could also discuss the feasibility of possible chemical
substitution, process modifications, and/or wastes segregation as means of
source control.
Chemical substitution may be possible if there are other compounds
that will fulfill the same function demanded of the chemical of
concern; assuming that the substitute itself does not exhibit any
properties with the potential to cause problems for the POTV. Key
factors in the feasibility of this option will be the cost and
availability of the substitute chemical; the chemical and physical
properties of the substitute and whether these properties will have a
substantive effect on the manufacturing process or subsequent wastes
handling operations/liabilities.
Process modifications that would reduce or eliminate the presence of
the chemicals of concern would be an attractive option if feasible.
It is likely that industry officials will have a better understanding
of the limitations to such modifications than POTV personnel, but this
should not inhibit inspectors from raising this option as a possi-
bility. Examples of process modification are the use of different,
more effective polymers during wastewater treatment, resulting in an
improved removal efficiency for the target pollutant; and changing the
5-5
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degreasing procedures utilized in cleaning product components,
possibly from immersion in solvent baths and subsequent rinsing with
water, to the wiping of the components manually with the solvent, and
air drying under a vacuum hood.
Waste segregation may be an effective means for improving wastewater
treatment efficiency. If the presence of more than one wastewater
component acts to limit the efficiency of a treatment process, it may
be possible to undertake some form of waste segregation (possibly by
distillation) that would separate the components sufficiently to allow
for efficient subsequent treatment.
In some instances the institution of formal procedures for the handling,
transfer, and storage of chemicals will be useful. For example, if a specific
chemical is only used in the manufacturing process in small quantities, the
dispensing of the chemical in bulk quantities could be discouraged. This
action would reduce the quantities potentially spilled during transfer and
also reduce the quantity of "left-over" chemicals that might be carelessly
discarded. In some instances the centralized storage of chemicals could
improve the logistics of chemical use supervision and provide a principle
point of focus for chemical management efforts.
The chemical management plan for each facility should be endorsed by
responsible officials at the facility and include a written commitment that
the practices described will be followed as a matter of company policy. In
instances where industries appear reluctant to implement the procedures
delineated in the management plans POTVs may wi-sh to withhold formal approval
of the management plan until a trial period illustrates that the procedures
are indeed being implemented.
5.3 SPILL CONTINGENCY PLANS
Many industries with large storage tanks onsite may already have spill
contingency plans in place, sometimes as a matter of company policy. This
kind of familiarity with planning and response procedures is a definite plus
from the POTV's point of view. However, existing spill plans may address only
a portion of the potential pollutant sources of concern to the POTW and may
not be as sensitive to protection of the sewer system as needed. Also, the
quantity and types of materials spilled that would initiate a spill response
under existing contingency plans may be inconsistent with pretreatment
5-6
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concerns and needs. Vith this in mind, POTV inspectors should carefully
review any existing plans for their adequacy as opposed to accepting them at
face value. The items which should be focused upon in reviewing a spill
contingency plan are the same as those considered in the design of a new plan
and include:
Identification of high risk chemicals
Identification of high risk handling and storage procedures and plant
locations
Identification and mapping of potential release points relative to
sewer access points
Identification of and preparation for possible spill containment
and/or countermeasures
Identification of individuals responsible for implementation of the
spill plan, individuals with the authority to commit additional
resources to a response action, if necessary; and designation of a
predetermined chain of command for coordinating spill response
activitiesdepending on the type of spill
Documentation of the entire spill contingency plan, including:
Maps of key area
- Equipment lists, and equipment storage and in-plant staging
locations
- Names and functions of all plant officials with a role in spill
contingency planning and implementation
- Names and phone numbers of POTV officials who should be contacted
in the event of a spill (the industry may choose to also include
local fire department, police, and emergency rescue information)
A commitment to provide the POTV with a written notification or
report within a short period (3 days) following an incident,
explaining the cause of the spill, and steps that are being taken
to prevent recurrentce
- An endorsement of the spill plan by responsible industry officials,
including a commitment to implement the plan as per the facility's
permit requirement
An indication as to the date when the plan was last updated, and a
commitment to update the plan periodically, or following a spill
incident.
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Inspectors should carefully review all the details of the plan and be
satisfied that it is adequate from the POTV's perspective before recommending
formal approval. Additional information on spill contingency plans may be
found in "EPA Region X Guidance Manual for the Development of Accidental Spill
Prevention Programs," U.S. EPA Region X, Seattle, WA, February 1986. An
example is also provided in Appendix K. In addition, EPA is currently
developing a guidance manual to help identify the need and method for
developing slug control plans.
5.4 BEST MANAGEMENT PRACTICES PLANS
The concept of best management practices plans (BMPs) is well accepted in
the NPDES program, and many of the same principles apply equally well to
indirect dischargers. In this section, the types of requirements that could
be required of an IU under the provisions of a BMP are discussed. As in the
case of the other types of management plans, the actual requirement imposed on
any particular industry will vary depending on site-specific needs.
Much of the focus of BMPs is on good housekeeping and proper operation
and maintenance measures. While these items may at first seem obvious or
trivial, experience has shown that the documentation of proper procedures and
a requirement that the procedures be followed are very effective in reducing
the number of (preventable) breakdowns in equipment, and miscommunication that
can lead to unwanted discharges to the sewers. In considering the need for
BMPs and in reviewing the design of BMPs proposed by industry, the following
should be considered:
Equipment 0 & M. While most facilities will make every effort to take
care of the equipment that they have purchased and installed for waste
management purposes, this cannot be assumed to always be the case.
Where equipment is at a level of sophistication that is beyond the
comprehension of its operators, or when the equipment is simply old,
attention paid to operation and maintenance practices becomes all the
more important. In such cases, BMP requirements should be directed at
ensuring that necessary routine maintenance is performed and that
equipment failures are not due to neglect. Where sophisticated elec-
tronics are a part of a treatment system.the manufacturers of such
equipment frequently provide either technical training or the option
of equipment maintenance contracts. These services should be encour-
aged by POTW staff wherever appropriate.
Reduction of contaminated runoff. The potential exists for contami-
nated runoff from any process operation, chemical transfer area, or
raw materials, product, or waste storage area that is exposed to
5-8
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rainfall. Walk, through inspections of a facility may reveal telltale
stains on the ground in problem areas. Depending on the nature of the
contamination, this type of runoff may be of concern. If the contami-
nated runoff is readily treated by the Ill's pretreatment processes and
does not contribute to hydraulic overloading of the system, then it
may be of little consequence. However, if pollutants (or the flow)
resulting from runoff appear to be a problem, then some form of
mitigation should be considered by the IU. After discussing the
problems and possible solution with industry staff, the POTV inspec-
tors should leave the selection of remedial measures to industry
management. Mitigative measures might include the construction of
berms and/or diversion structures, the shifting of operations to
covered areas, recontouring of surfaces, or even the modification of
pretreatment systems onsite. The ongoing maintenance and implementa-
tion of runoff control measures are appropriately contained in the
facility's BMP.
Segregation of wastes for reclamation. In some instances, oppor-
tunities will exist to segregate wastes within a facility for the
purpose of reclamation. This practice also reduces the quantities of
possibly hazardous waste that must be disposed and may even reduce
pollutant loadings in the wastewater. Contaminated oils and spent
solvents are examples of wastes for which a substantial reclamation
market exists.
Routine cleaning operations. Many industries will schedule a routine
cleaning of plant areas and possibly equipment. This may come at the
end of every few shifts, on specified days of the week, or possibly at
the end of seasonal operations. While this kind of cleaning activi-
ties are necessary for the continued efficient (and perhaps sanitary)
nature of plant operations, the use of large quantities of detergents
and solvents, and the pollutants carried along by these chemicals, can
be of concern. In some instances, it is possible for industries to
reduce the loadings to the sewers through the substitution of dry
methods of cleaning or possibly modifying cleaning procedures. For
instance, it is often possible to achieve highly efficient cleaning of
surfaces while reducing chemical usage by using high pressure applica-
tion wands. This type of chemical application also allows for more
directed application and more efficient chemical usage. When review-
ing routine cleaning operations, POTWs should also endeavor to ensure
that required cleaning of grease traps are indeed conducted with
necessary frequency. Once again, the use of formal procedures, and
perhaps even operations log books could be of help.
Chemical storage practices. A walk through of a facility's process
operations may reveal that chemicals and fuels are being stored
adjacent to, and perhaps directly over floor drains (so that leaks and
drips do not make a mess). This kind of practice should be strongly
discouraged and is perhaps the simplest type of preventative measure.
Also, if a facility acknowledges routine amounts of chemical spillage
and leaks (perhaps during dispensing chemicals) with the use of drip
pans, it is probably worth inquiring as to the frequency with which
these pans are emptied, whose responsibility it is, and where and how
the spilled substances are disposed.
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5.5 LEGAL AUTHORITY CONSIDERATIONS
All POTVs must have the minimum legal authority required by 40 CFR
403.8(f)(i), to deny or condition discharges o£ pollutants that could violate
local or Federal pretreatment standards and requirements. The goals of
management practice requirements are the same as those of numerical local
limits to prevent pass through, interference, and violations of the
specific prohibitions. However, the imposition of the management plans
described in this chapter may or may not be within the scope and authority of
some local ordinances. Therefore, it is suggested that each POTV specifically
evaluate its legal ability to impose these requirements. Once verified or
obtained, specific requirements for industrial users to submit a management
plan should be included in the user's control mechanism (i.e., industrial user
permi t).
5.6 APPROVAL OF INDUSTRIAL USER MANAGEMENT PLANS
Once the need for a chemical management plan, spill prevention plan or
BMP is determined, the POTV may require the plan(s) to be submitted in
conjunction with the industrial user's permit application and approved in
conjunction with issuance of the permit. The industrial user permit should be
reissued to include the requirements of the management plan if necessary.
Satisfactory implementation of the plans should then be verified during the
periodic industrial inspections by the POTV.
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TABLE 5-1.
Solvent
Acetone
Benzene
n-Butyl alcohol
Carbon disulfide
Carbon tetrachloride
Chlorobenzene
Cresols (o-m-p isomers)
Cyclohexanone
1,2-Dichlorobenzene.
Dichlorodifluoromethane
2-Ethoxyethanol
Ethyl acetate
Ethyl benzene
^ Ethyl ether
Isobutanol
Me thanol
Methylene chloride
Methyl ethyl ketone
Methyl isobutyl ketone
Nit robenzene
2-Ni tropropane
Pyridine
Te t rachloroe thylene
Toluene
1.1.1-Trichloroethane
1.1.2-Trichloroe thane
Trichloroethylene
Trichlorofluoromethane
1,1,2-Trichloro-l,2,2-trifluoroethane
Xylene (o-m-p isomers)
OP COMMONLY USED SOLVENTS
CU A
RCRA RCRA Proposed Priority
Igni tabili ty Toxici ty TCLP Pollutant
Yes
No
No
No
Yes
Yes
Yes
Yes
Yes
No
No
No
Yes
Yes
Yes
No
No
Yes
Yes
Yes
No
Yes
Yes
Yes
No
Yes
Yes
No
Yes
No
No
No
No
Yes
Yes
Yes
No
Yes
No
No
Yes
Yes
No
No
Yes
No
No
No
Yes
No
No
Yes
Yes
No
No
No
Yes
Yes
Yes
No
Yes
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
No
No
No
No
Yes
Yes
Yes
Yes
Yes
No
No
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
No
Yes
Yes
Yes
No
Yes
Yes
Yes
No
Yes
No
No
No
Yes
No
No
Yes
No
No
No
-------
6. CASE BY CASE PERMITS - BEST PROFESSIONAL JUDGMENT (BPJ)
6.1 INTRODUCTION
This section of the guidance manual is devoted to developing permit
limits on a case-by-case, IU-specific basis. The limits are for pollutants of
concern for which local limits have not been developed by any of the other
methods already described in this manual. This section explains the
procedures that can be used to develop the actual wastewater discharge permit
limits. Many of the concepts and procedures used in the NPDES program have
applicability to the pretreatment program and therefore will be discussed.
For NPDES direct dischargers, permit limits for these types of facilities are
referred to as Best Professional Judgment (BPJ) permit limits. BPJ is defined
as the permit writer's best judgment, reflected in permit limits, as to the
most effective control techniques available, after consideration of all
reasonable available and pertinent data or information which forms the basis
for the terms and conditions of a permit. POTVs should take information
submitted by their IUs into consideration when applying BPJ. Vorking closely
with IUs to develop BPJ local limits will often identify additional practical
considerations and result in better limits.
6.2 APPLICATIONS OF BPJ
In this section some of the appropriate applications of BPJ to local
limits derivation are discussed. In every case, the local limits which are
developed must, as a minimum, prevent violation of State and local
requirements as well as pass through, interference, and violations of any of
the specific prohibitions in the General Pretreatment Regulations.
(1) BPJ can be used to allocate maximum allowable headworks loadings by
the selected industrial reduction method discussed previously in
Section 3.3.3.1. This allocation method generally involves a BPJ
evaluation of treatment performance data in order to establish
expected IU pollutant removals through pretreatment.
(2) BPJ can be used to establish pretreatment requirements when there
are insufficient data/criteria to do a headworks loading analysis
for a pollutant of concern. For example, the pollutant could be a
new toxic chemical, a suspected carcinogen for which the long-term
health effects are unknown, a bioaccumulative pollutant, a pollutant
which concentrates in sediments, or a chemical for which analytical
methods are unavailable. In these cases the POTV may be uncertain
as to safe quantities of the chemicals involved, and therefore will
6-1
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attempt to minimize the discharges of these chemicals by making a
BPJ determination of the best available treament technology (or
chemical management practice). The POTV would then develop case-
by-case permit limits for IUs based on the expected treatment
performance.
(3) It can be used when biomonitoring tests have shown toxicity of the
whole POTV effluent, but the toxicity cannot be traced definitely to
one or a few specific causes. Through the toxicity reduction
evaluation techniques described in Section 2.5, the general class of
contaminants causing the toxicity may be identifiable (such as
metals, acids, filterable materials, volatiles, polar or nonpolar
organics, etc.). The POTV can then determine who is discharging
these materials and use BPJ to determine what type of pretreatment
would be effective in reducing them.
(4) It can be used to further the basic goal of the Clean Vater Act,
which is to minimize the release of pollutants and prohibit
dilution. Although a discharge may not be causing an apparent
problem at a POTV, if an industrial user is discharging small
quantities of highly concentrated toxic wastes to the sewer
untreated and relying on dilution to hide the problem, the POTV will
want to regulate the discharge. This can be done through
technology-based limits or chemical management practice require-
ments. The exception would be if the POTV can demonstrate that its
own treatment processes consistently reduce the pollutant as
effectively as pretreatment alternatives.
(5) It can be used to control discharges from centralized hazardous
waste treaters and other dischargers of highly variable wastes.
Centralized hazardous waste treatment facilities are becoming more
common throughout the country as RCRA regulations become more
stringent. They accept wastes that used to be hauled to hazardous
waste landfills from diverse generators. The waste is complex and
varying in quality. It may be difficult for the POTV to evaluate
individual pollutants on a water quality/sludge/POTV effects basis.
The POTV will want to be assured of adequate treatment and reliable
operation of pretreatment facilities. It may choose to use BPJ to
establish a total toxic organic (TTO) limit plus individual
technology-based limits for certain pollutants.
6.3 APPROACHES TO BPJ
Several BPJ approaches are discussed in this section. Based on this
discussion of BPJ methods it will be evident that BPJ allows the permit writer
a great deal of flexibility in establishing permit limits. Inherent in this
flexibility, however, is the burden on the permit writer to show that his/her
BPJ is based on sound engineering analysis. The methods set forth in this
document are aimed at illustrating several common approaches to a solution.
6-2
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It is important to remember that the technical basis for the limits should be
clearly defined and veil documented.
The following approaches vill be discussed:
Existing permit limits for comparable industrial facilities
The demonstrated performance of the permittee's currently installed
treatment technologies (performance-based limits)
The performance of treatment technologies as documented in engineering
literature (treatability)
Adapting Federal standards that regulate similar vastestreams (trans-
fer of regulations)
Economic achievability considerations in permit limits development.
Examples are provided at the end of this section.
6.3.1 Existing Permit Limits for Comparable Industrial Facilities
One straightforward method for establishing BPJ permit limits is to
identify and use existing permit limits for comparable industrial facilities.
One way to obtain information about comparable facilities is to contact NPDES
permit writers at the State or EPA Regional offices. In addition, there is an
EPA document, Abstracts of Industrial NPDES Permits, which presents abstracted
data from the NPDES permits of 500 industrial dischargers to surface waters
(not to POTWs). The document is available by request from the Permits
Division (EN-336), EPA Headquarters, Office of Water Enforcement and Permits.
Within each permit abstract, the following information is presented:
Industrial facility name
Description of products and manufacturing processes
Identification of wastewater discharges
Description of wastewater treatment
A statement of permit limits and a discussion of the basis for the
permit limits.
6-3
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To use this document effectively, the permit writer must first identify
industrial facilities similar to the facility to be permitted. The permit
writer should select facilities with regard to the following characteristics:
Manufacturing processes
Pollutants
Process wastewater sources and flows
Nonprocess wastewater (e.g., cooling water) flows
Treatment technologies and practices.
Once permit abstracts of similar industrial facilities have been
identified, the permit writer should review the permit limits for each, and
examine the basis behind them. The permit writer then should assess the
applicability of these permit limits to the industrial discharge to be
permitted. The permit writer should compare the wastewater treatment system
at his particular industrial user to the direct discharger's system. If the
two wastewater treatment systems are comparable, then the permit writer may
want to consider establishing similar permit limits. Prior to establishing
similar limits, the permit writer should also consider the effectiveness of
the POTV itself in removing the pollutants of concern and avoid redundant
treatment. If the POTV consistently reduces the pollutants of concern as
effectively as pretreatment alternatives, then pretreatment may be
unnecessary. However, POTVs are generally not designed to treat toxic or
hazardous industrial wastes and whatever removal is incidentally achieved may
be highly inconsistent from day-to-day.
Another consideration in using the NPDES permit to establish BPJ limits
is that NPDES permit limits are frequently based on water quality considera-
tions. Water quality based limits are usually developed from an in-stream
water quality standard and back-calculated from the amount of dilution pro-
vided by the receiving stream to arrive at the permit limit for a particular
discharger. The permit writer should determine if the permit limits are water
quality based. In such a case, even if the wastewater treatment technologies
are similar, the numerical NPDES permit limit is probably not transferable to
an industrial user of a POTV. Example 1 demonstrates this approach.
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6.3.2 Demonstrated Performance of the Industrial User's Treatment System
The permit writer can base permit limitations for an industrial user on
the performance of the user's existing treatment system. Such permit limits
are referred to as performance-based limits. In employing this practice, the
permit writer must adequately assess the influence of the user's operational
characteristics on the performance of the treatment system. In particular,
the variabilities of the industrial user's production rates and their rela-
tionship to raw waste loadings and treatment efficiency, must be considered.
Permit limits based on poor treatment system performance are not allow-
able and for this reason before a permit writer can develop performance-based
permit limits, it must be determined that the wastewater treatment system is
operating properly and efficiently. To do this, the permit writer should
visit the industrial user's facility and treatment system. During the site
visit, one should look, for obvious indications of poor performance such as
high solids going over the clarifier weir, poor maintenance, and other signs.
The writer should obtain design data (i.e., volumes of tanks, unit processes,
overflow rates, etc.), operational data (flows, analytical data, daily
operating time for batch and intermittent operations, etc.), production data
and monitoring data. These data can be used to determine if the wastewater
treatment system is overloaded and if the proper treatment processes are
employed.
Only after the permit writer has determined that the performance of the
treatment system is adequate, can he/she develop performance-based permit
limits using the monitoring data for the industrial user's discharge. The
limits can be set at a level so that if the treatment system maintains the
desired level of performance, the probability of exceeding the limits is very
low (less than 0.05). Since effluent quality will vary over time, statistics
are used to describe the effluent characteristics and treatment performance.
Normally, a permit writer relies on at least two years of raw discharge data
for each pollutant. Two years of data, provided the data are at least
monthly, are recommended to obtain a sufficient number of data points to use a
statistical method to determine the performance-based permit limits. The two
years of data can be the most recent two years or the two years of highest
6-5
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production during the last five years. Before using the highest production
years, the permit writer should check to see that the treatment system was not
overloaded during the high production periods. Using the raw data, the permit
writer should first calculate the mean and standard deviation for each
pollutant of concern and with these values, derive the permit limits
(equations found in Example 2). It should be noted, however, that treated
effluent data are lognormally distributed and require additional statistical
procedures than those given in Example 2. The permit writer is directed to
the Technical Support Document for Water Quality-Based Toxics for the more
detailed technical information.
Monthly average values should not be used in place of the raw data when
developing performance-based permit limits. These values are averages and
consequently much of the day-to-day variability in a pollutant will be
smoothed out. The loss of variability can result in permit limits which are
too stringent for the treatment system to meet and could result in excessive
and unnecessary violations. Example 2 illustrates how to calculate
performance-based permit limits and the effect of using monthly averages
rather than raw data.
6.3.3 Performance-of Treatment Technologies as Documented in Engineering
Literature (Treatability)
Another method for establishing BPJ permit limits for a given industrial
discharge is based on the performance of various treatment technologies for
the removal of specific pollutants. The practice will assist the permit
writer in understanding what level of treatment is possible. From this
information the permit writer can compare the available technologies and
treatment level to those at the industrial user in question. Developing BPJ
limits from the documented treatability data can be approached in two distinct
ways:
Limits for a facility can be based on the performance of treatment
technologies installed at other facilities performing identical
processing operations
Limits on a facility's discharge can be based on the performance of
treatment technologies in removing specific pollutants from waste-
streams with similar characteristics and pollutant levels, but
discharged by industrial facilities performing completely different
process operations.
6-6
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In general, the considerations involved in using treatability data to set
BPJ limits are the same for both of the above approaches. Major considera-
tions are:
Performance data should be based on the removal of identical or
chemically similar pollutants to those found in the discharge to be
permi tted
Performance data should pertain to the treatability of wastewaters
containing approximately the same pollutant levels as those found in
the discharge to be permitted
Compositional differences between the discharge to be permitted and
the discharge for which treatability data are available should be
noted
The variability in pollutant levels in the discharge to be permitted
will affect treatability.
The permit writer should note major differences between the average flow of
the discharge for which treatability data exist and the average flow of the
discharge to be permitted.
In order to assess wastewater treatability, available performance data
should be obtained that documents the efficiency of existing treatment
technologies in removing identical, or at least chemically similar, pollut-
ants. The rationale for this consideration is that treatment technologies
remove similar pollutants with similar efficiencies. Treatment technologies
usually are geared toward the removal of specific pollutants (e.g., air
stripping units remove volatile organics, precipitation units remove metals,
etc.).
A second consideration is that performance data should be obtained that
reflect the treatability of wastewaters containing approximately the same
pollutant levels as the discharge to be permitted. The permit writer might
find this consideration particularly important when available performance data
pertaining to the treatability of was test reams generated by industrial
processes are dissimilar from the data of the industrial facility to be
permitted.
6-7
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A third consideration in applying technology transfer is that compo-
sitional differences between the wastewaters for which performance data are
available and the wastewater discharge to be permitted should be identified
and expected influences on treatability should be determined. For example,
suppose a permit writer is to develop a permit limit for copper and perform-
ance data for an analogous wastestream indicate high removals can be achieved
through precipitation techniques. Before applying a high copper removal
efficiency to the industrial discharge to be permitted, however, the permit
writer should be careful to note whether high levels of ammonia also are
present in the discharge. Ammonia tends to form complexes with copper, which
conceivably could affect the treatability of the wastewater. In such a case,
the permit writer may wish to set discharge limits based on stripping of the
ammonia prior to precipitation of the copper, or alternatively, set a less
stringent limit on copper to allow for some pass through due to complexation.
The following list (by no means exhaustive) provides examples of pollu-
tants that commonly cause interference with the performance of treatment
technologies, and consequently, pollutants that the permit writer should try
to identify:
Ammonia - As noted above, ammonia can form chemical complexes with
metals, and consequently, lower metals removal efficiencies.
Iron - Iron tends to form complexes with cyanide, and consequently,
reduce cyanide treatability.
Surfactants - The foaming action of surfactants can reduce volatiles
removal by air stripping. Emulsification of insoluble organics by
surfactants might reduce the removal of these pollutants by absorption
onto activated carbon.
Oil and grease - Oil and grease tends to saturate treatment systems
that rely on beds, such as activated carbon and ion exchange. Oil and
grease saturation could drop removal efficiencies in these units to
zero.
pH - pH affects the operation and efficiency of many treatment
technologies. For example, organic acids are removed better in
activated carbon columns at low pHs than at neutral or high pHs.
Chemical dosing rates in neutralization and/or precipitation systems
depend on pH, floe formation, and other factors.
6-8
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In addition to the considerations cited above, the permit writer should
be aware of the variability of pollutant levels in the discharge to be
permitted. Removal efficiencies of treatment technologies tend to vary
greatly with wide fluctuations in influent level; therefore, removal effi-
ciencies based on the operation of technologies treating wastewaters with
uniform, invariant pollutant levels may not adequately reflect the performance
of the same technologies in treating highly variable pollutant discharges.
The permit writer should be aware of the variabilities in the pollutant
discharges, and should take these variabilities into account when assessing
the applicability of performance data in developing permit limits.
Finally, the permit writer also should consider the magnitudes of the
wastewater discharges. Even though a particular treatment technology performs
well on a small discharge, the permit writer may find that it is technically
and/or economically infeasible to install the particular technology on the
larger scale necessary for treatment of greater discharges. Major considera-
tions concerning treatment scale-up include:
Requisite land area for the treatment facility
Cost of treatment media (e.g., activated carbon, resin beds, etc.)
Cost of treatment chemicals
Energy requirements for operation of treatment facility.
The engineering literature provides a wealth of information concerning
the performance of treatment technologies and treatability of specific
pollutants. Probably the documents of most value to a permit writer are EPA's
Treatability Manual [59] and the Development Documents (see Appendix D of this
manual for a list of those currently available).
EPA Development Documents present industry and wastewater characteriza-
tion data, as well as both actual and theoretical treatment technology
performance data, for numerous categories of industrial facilities. The
documents have been prepared by EPA's Industrial Technology Division to
support the development of technology-based discharge limitations.
Specifically, each Development Document contains the following information for
an industrial category:
6-9
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Description of the industrial category, number and size of manu-
facturing sites, production characteristics, and age and geographic
distribution of facilities.
Characterization of vater use and wastewater generation within the
industrial category. Sampling data for both treated and untreated
wastewaters from representative facilities within the industrial
category.
Discussions of alternative treatment technology options, as well as
presentation of removal efficiency data for actual and theoretical
treatment systems.
EPA's Treatability Manual is a five-volume document pertaining to the
effectiveness of treatment technologies in removing pollutants from industrial
wastewaters. The first volume of the manual presents physical/chemical
property data, industrial wastewater occurrence data, treatment removal
efficiencies, typical industrial effluent concentrations, and water quality
criteria for specific pollutants.
The second volume provides descriptions of industrial facilities and
wastewaters, which will be valuable in assessing the applicability of various
treatment technologies. The third volume discusses treatment technologies and
presents performance information. The fourth volume presents data on treat-
ment technology cost estimating. The permit writer could use these data to
assess the economical feasibility of the treatment technology options. The
fifth volume of the Treatability Manual is a summary volume.
Example 3 is an example of the use of treatability data from the litera-
ture in setting BPJ permit limits.
6.3.4 Adapting Federal Discharge Standards
Another potential basis for the development of BPJ discharge limits is
the use of existing technology-based Federal discharge standards for similar
industries and/or wastestreams. The rationale for the use of existing Federal
standards is that compliance with such standards is predicated upon the
installation of appropriate pollution control technologies; if the permit
writer adopts technology-based standards for inclusion in a permit, the
permitted industry similarly will have to install the appropriate pollution
control technologies to comply.
6-10
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The permit writer should identify an industrial category or categories
regulated by national categorical standards that is relevant to the facility
to be permitted. The permit writer should consult the Federal Register at
this point to determine if the specific technology-based discharge limitations
can be applied reasonably to the discharge to be permitted.
EPA has noted that many permit writers have used electroplating and metal
finishing standards (40 CFR 413 and 433) in developing BPJ permit limits for
metals dischargers other than electroplaters/metal finishers. It must be
realized that the metal finishing standards only reflect the wastewater
characteristics and treatability of electroplating/metal finishing waste-
waters, and that these standards may not be appropriate for BPJ permit limits
for other categories of metals dischargers, such as copper formers.
In order to provide a more representative data base of all metal dis-
charging industries, EPA established the combined metals data base. The
combined metals data base consists of effluent data for metal finishing,
copper forming, battery manufacturing, and coil coating industries, as well as
other industries that discharge metals and use similar metals removal treat-
ment technologies. Table 6-1 presents mean effluent data from the combined
metals data base, as well as monthly and daily variability data. Table 6-1
also presents corresponding monthly average and daily maximum "discharge
limits" as guidance for the permit writer in setting BPJ permit limits. Also
presented are metal finishing effluent discharge limit data for comparison.1
Permit writers should use their own judgment in selecting which of these data
bases to employ.
Example 4 demonstrates the use of technology-based discharge standards
for similar wastestreams in setting BPJ permit limits.
*The monthly average and daily maximum metal finishing limits in Table 6-1 are
the categorical preteatment standards for existing sources (PSES). The
long-term arithmetic mean data in the table represent the long-term perfor-
mance which was found to be attainable by the technology EPA assessed. If a
plant intends to consistently comply with the regulatory limit, it should use
the long-term mean as a guide for design.
6-11
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6.4 "Regulatory considerations for developing bpj local limits
The Federal Pretreatment Regulations (40 CFR Part 403) do not include
regulatory constraints on a POTV's development of BPJ permit limits for
indirect dischargers. The permit writer has considerable latitude in estab-
lishing case-by-case permit limits for indirect dischargers, but must, as a
minimum, assess the potential impacts of pollutant discharges on the operation
of the P0TW and develop limits as necessary to prevent pass through, inter-
ference, and violations of any of the specific prohibitions contained in the
General Pretreatment Regulations. The permit writer also may wish to consider
the requirements delineated by Federal regulations for direct discharger
permits. These are discussed briefly below.
In developing BPJ permit limits for direct dischargers (NPDES pemit
limits), the permit writer is required by Federal Regulations [40 CFR Part
125.3(C)3] to consider the following:
The age of wastewater treatment equipment and facilities
The nature of the wastewater treatment process employed
Engineering aspects of the application of various treatment
technologies
Requisite process changes in order to comply with the permit limit(s)
Nonwater quality environmental impacts associated with treatment
technologies
The cost of achieving effluent reductions.
Clearly, the age of wastewater treatment equipment will affect the
equipment's expected performance. Reasonable permit limits should take into
account factors relating to the the expected actual performance of currently
installed treatment units, such as age and type of equipment, as long as the
technology is appropriate for the type of wastewater.
The permit writer also should account for the engineering aspects of the
application of various treatment technologies. Permit limits should not be
predicated on the application of technologies that are impossible to install
from an engineering standpoint. For example, the permit writer should not
develop a permit limit based on the installation and proper operation of a
6-12
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treatment technology which occupies three-eighths o-f an acre if the entire
industrial facility consist of only one-quarter of an acre.
The permit writer should consider all industrial process changes that
must be affected in order to comply with the permit limit. In particular, the
permit writer should determine whether requisite changes in operational
procedures, management practices, etc., alone will be sufficient to achieve
compliance with the nev permit limits, or whether installation of treatment
technologies will be necessary. Also, the permit writer should assess the
technical and economic feasibility of all process modifications required for
compliance with the permit limit.
Additionally, the permit writer should consider all nonwater quality
environmental impacts associated with the requisite treatment technologies.
Nonwater quality impacts include the following:
Air pollution impacts (e.g., discharge of volatiles to the air by air
stripping treatment technologies)
Hazardous waste generation (e.g., metals-bearing sludges generated by
precipitation treatment technologies)
Energy requirements associated with the treatment technologies (less
energy intensive treatment technologies should be preferentially
considered).
A final factor that the permit writer should consider when establishing
case-by-case permit limits for direct dischargers is the cost of the requisite
treatment technologies. This consideration is discussed in detail in Volume
IV of the Treatability Manual [59]. Where economic achievability may be an
issue, the permit writer may wish to consult a manual entitled Protocol for
Determining Economic Achievability for NPDES Permits (65].
Finally, Federal regulations [40 CFR Part 122.44(1)] require that renewal
permits issued to direct dischargers must contain permit limits at least as
stringent as those in the dischargers' previous permits. Thus, the permit
writer cannot establish case-by-case permit limits for a direct discharger
that are less stringent than those with which the direct discharger must
6-13
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already comply. The only exceptions alloved under 40 CFR Part 122.44(1) are
cases for which the old permit limits are more stringent than subsequently
promulgated Federal limitations, and:
Previously installed technology is deemed inadequate to ensure
compliance with the old permit limits
Material and substantial changes to the facility have occurred, making
compliance with the old permit infeasible
Increased production drastically reduces treatment efficiency
Operation and maintenance costs for the installed treatment technology
are considerably greater than costs considered in promulgating the
Federal limitation.
6-14
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TABLE 6-1. COMPARISON OP COMBINED METALS DATA BASE
WITH METAL FINISHING DATA BASE
Parameter
Long-Term
Ari thmetic
Mean
Monthly (10-day) Ave.
Daily Maximum
Variabili ty
Limi t
(mg/)l
Variability
Limi t
(mg/i;
METAL FINISHING:
Total Chromium
0.572
2.98
1.71
4.85
2.77
Copper
0.815
2.54
2.07
4.15
3.38
Lead
0.197
2.19
0.43
3.52
0.69
Zinc
0.549
2.70
1.48
4.75
2.61
Cadmium
0.130
2.02
0.26
5.31
0.69
Nickel
0.942
2.53
2.38
4.22
3.98
Total Cyanide
0.180
3.61
0.65
6.68
1.20
Hexavalent Chromium
0.032
3.05
0.10
5.04
0.16
Cyanide, amenable
0.060
5.31
0.32
14.31
0.86
TSS
16.8
1.85
31.0
3.59
60.0
COMBINED METALS DATA
BASE:
Total Chromium
0.084
2.14
0.18
5.24
0.44
Copper
0.58
1.26
0.73
3.28
1.90
Lead
0.12
1.08
0.13
1.25
0.15
Zinc
0.33
1.85
0.61
4.42
1.46
Cadmium
0.079
1.90
0.15
4.30
0.34
Nickel
0.74
1.72
1.27
2.59
1.92
TSS
12.0
1.67
20.0
3.42
41.0
6-15
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EXAMPLE 1 APPLICATION OF THE COMPARABLE FACILITIES APPROACH
A manufacturer (ABC Corporation) of organic chemicals discharges an
average of 0.200 MGD of process wastewater to a POTV. This wastewater is from
the production of alkyd resins, urea resins and polyester resins. The
wastewater is pretreated by neutralization, an aerated lagoon and a polishing
pond prior to discharge. The plant manager has indicated that lead or cadmium
are used as catalysts and phenol is an additive in the polyester resin
process. No other priority pollutants are used. Upon scanning the EPA
document, Abstracts of Industrial NPDES Permits, the permit writer may
identify the following citation concerning the permit for another organic
chemicals manufacturing facility:
XYZ Corporation is a manufacturer of formaldehyde and synthetic resins
including urea-formaldehyde, phenol-formaldehyde, polyester and alkyl
resins and discharges to the Clear River. The facility's process outfall
consists of 0.135 MGD of process wastewater which is treated by equali-
zation, neutralization, activated sludge treatment, clarification, lagoon
stabilization and sand filtration.
There are no National Effluent Guidelines promulgated for this industry
and consequently effluent limitations have been developed using BPJ and
water quality standards. The basis for the BPJ limitation is BCT = 95
percent reduction in raw B0D5, TSS and COD. Ammonia and total phenols
are limited at demonstrated treatment plant performance levels per
BAT/BPJ and water quality standards. Styrene and xylene are limited at
3.0 mg/1 (instantaneous maximum) based on water quality criteria. Zinc
is limited at 2.0 mg/1 per State Hazardous Metals Policy (i.e., five
times the single reported value). Formaldehyde, also a hazardous
compound but not a priority pollutant, is not limited because BOD and COD
are considered to be indicator parameters. The NPDES permit limits are
summarized in the table on the following page.
The permit writer for the P0TW notes that with the exception of formalde-
hyde production, the production processes at the two facilities are similar.
The permit writer decides that 95 percent removal of B0D5, TSS and COD is
beyond the capabilities of the ABC Corporation's pretreatment system after
reviewing the performance data. Because ABC Corporation is discharging to a
POTV rather than directly to surface waters, the permit writer elects to
6-16
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XYZ Corporation
Effluent Limits for Process Wastewater Outfall
Pollutants
Avg/Max. Limits and Units
Moni toring
Flov
BOD
COD
TSS
NL
9.1/18.1 Kg/d (18/25 mg/1)
152/227 Kg/d (298/444 mg/1)
18/36 Kg/d (35/70 mg/1)
2.3/4.6 Kg/d (4.5/9.0 mg/1)
0.02/0.04 Kg/d (0.04/0.08 mg/1)
3.0 mg/1 inst. max.
3.0 mg/1 inst. max.
2.0 mg/1 inst. max.
6.0-9.0
continuous, recorded
2/veek
2/veek
2/veek
2/veek
2/veek
1/month
1/month
1/month
Ammonia-N
Total phenols
Styrene
Xylene
Zinc
pH
continuous
develop B0D5, COD and TSS permit limits based on 80 percent removal. These
methods would result in B0D5 limits of 93/117 mg/1 which are within the range
of the raw domestic sewage concentrations received by the P0TV. In XYZ
Corporation's NPDES permit, the ammonia-N and total phenols limits were based
on treatment plant performance and water quality standards. Because the
industrial user is discharging to a P0TW, water quality-based limits are not
necessary unless the industrial user contributes a pollutant which causes the
P0TV to violate water quality standards in the receiving stream. Upon
reviewing the industrial user's discharge data, the permit writer finds that
the concentration limits for ammonia-N in the XYZ Company's permit are
achievable by the industrial user; however, the total phenol limits are not.
The permit writer elects to limit ammonia-N at the same concentration as XYZ
Corporation and to base the total phenols limits on the performance of the
industrial user's pretreatment system. The limits for both pollutants are
sufficient to protect the water quality in the receiving stream after the
industrial discharge receives further treatment at the P0TW.
Since the styrene and xylene limitations in XYZ Corporation's permit were
based on water quality but the receiving stream to which the P0TV discharges
has no water quality criteria standards or criteria for these pollutants, and
since these pollutants have not been detected at the P0TW, they are not
included in the industrial user's permit. Zinc, like ammonia-N and total
phenols, has a water quality standard in the POTV's receiving stream in
addition to being a priority pollutant. The industrial user's discharge data
6-17
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indicates a low zinc concentration so it is not limited. The industrial user
indicated that lead and cadmium are used as catalysts in production, and
phenol (Priority Pollutant No. 065) is an additive. Since lead and cadmium
are used as catalysts, very little is expected to be discharged in the process
wastewater and this is confirmed by the industrial user's discharge data. The
permit writer decides to require monitoring rather than limits for these since
they are priority pollutants and are known to be used at the facility. Phenol
is included in the total phenols analysis and limit, so the permit writer does
not require a separate limit for the priority pollutant itself.
6-18
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EXAMPLE 2 PERFORMANCE-BASED PERMIT LIMITS
Jones Mining Company operates a molybdenum mine and mill producing less
than 5,000 metric tons of ore per year. The wastewater (mine drainage) from
this small facility is discharged to a POTV. Molybdenum ore mining and
dressing is regulated under Subpart J of 40 CFR Part 440, but no categorical
pretreatment standards have been promulgated for the industry. The permit
writer has considered applying the appropriate BPT and BAT limitations for
direct dischargers to this facility. However, he has decided to calculate
performance-based limits to see how comparable they are to the BPT/BAT limits.
Using the raw data below (assumed to be normally distributed) and Equations
1-4 below, the permit writer calculates the following for zinc and TSS:
Zinc TSS Zinc (using monthly averages)
Mean (X) 1.30 66 1.30
Standard deviation (s) 1.74 7.44 1.56
All values are in mg/1. The permit writer estimates the daily maximum and
monthly average limits using Equations 3 and 4 and establishes sampling
frequencies of twice per month for zinc and once per month for TSS.
Zinc TSS Zinc (using monthly averages)
Daily Maximum Limit 4.15 78. 3.87
(mg/1)
Monthly Average Limit 3.31 78. 3.11
(mg/1)
The resulting performance-based limits are not as stringent, as the correspond-
ing BPT/BAT limits for direct dischargers. The permit writer also notices .
that when the sampling frequency is once per month, the monthly average limit
is the same as the daily maximum; the more frequent the sampling, the more
stringent the limit. Using the monthly average values instead of raw data to
calculate performance-based limits results in more stringent limits because
the variability as reflected in the standard deviation is smoothed out
somewhat.
6-19
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Zx,
X =
Equation 1
where: X
x.
i
n
mean of the data points
the individual data points
the number of data points upon which the mean is based.
s =
' E (xr x)'
n-1
Equation 2
where!
standard deviation.
Daily Maximum Limit = X + Zs Equation 3
where Z = 1.645 for the 95th percentile.
Zs
Monthly Average Limit = X + Equation U
~K
where N = the number of samples to be taken per month.
6-20
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RAW DATA PERFORMANCE-BASED PERMIT LIMITS
Raw Data Monthly Average
Zinc
TSS
Zinc
Month
(mg/1)
(mg/1)
(mg/1)
Jan.
0.43
54
0.77
2.82
3.90
6.20
Feb.
5.50
68
5.80
5.02
4.30
4.50
Mar.
4.80
69
3.34
3.70
0.55
4.30
Apr.
0.40
66
0.33
0.33
0.35
0.25
May
0.18
64
0.25
0.23
0.23
0.25
June
0.82
83
2.10
1.18
1.00
0.78
July
0-68
72
0.33
0.40
0.27
0.32
Aug.
0.95
70
0.27
0.45
0.32
0.25
Sept.
0.20
57
0.40
0.28
0.28
0.22
Oct.
0.25
65
0.033
0.22
0.30
0.28
Nov.
0.87
61
1.10
0.65
0.17
0.45
Dec.
0.75
66
0.85
0.73
1.00
0.77
0.28
X
1.30
~66
T730
s
1.74
7.44
1.56
Note: For illustrative purposes, only one year of data was used rather than
the recommended two years of data.
-------
EXAMPLE 3 APPLICATION OF LITERATURE TREATABILITY DATA
An industrial user discharging treated process wastewater from the
manufacturing of trinitrotoluene (TNT) is to be permitted. EPA issued a
Notice of Interim Final Rulemaking on March 9, 1976 (40 CFR Part 457, 41 FR
10180), for best practicable control technology (BPT) for Subcategories A (the
manufacture of explosives) and C (the loading, assembling, and packing of
explosives) of the industry. Best available technology (BAT) and Pretreatment
Standards for Existing Sources (PSES) regulations, however, have been deferred
by EPA.
The literature was reviewed to compare the performance of this industrial
facility's activated carbon system to other facilities for removal of TNT.
This information is summarized below. The carbon system was determined to
experience influent levels and loading rates comparable to other facilities.
The reported effluent TNT concentrations and percent removal fall within the
ranges reported for other facilities. The data show a removal rate of
approximately 98 percent for TNT wastewaters. The wastewaters are composed of
TNT (trinitrotoluene), 2,4-dinitrotoluene and 2,6-dinitrotoluene. Using the
influent data for the facility, the permit writer calculated limits for
trinitrotoluene, 2,4-dinitrotoluene and 2,6-diriitrotoluene equivalent to 98
percent removal.
COMPARISON OF ACTIVATED CARBON REMOVAL DATA FOR TNT WASTEWATERS
Influent TNT
Effluent TNT
Percent
Reference
mg/1
mg/1
Removal
1
1,000
1
99.9
2
54
1
98.1
3
118
2.6
97.8
4
423
2.7
98.0
References:
1. Demek, Mary M., et al., Studies on the Regeneration of Active Carbon
for Removal of L-TNT from Wastewaters, Edgevood Arsenal Technical
Report. EC-TR-74008 (May 1974).
6-22
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2. Schulte, G. R., Robert C. Hoehn, and Clifford W. Randall, "The
Treatability of a Munitions Manufacturing Waste with Activated
Carbon," pp. 150-162 in Proceedings of the 28th Purdue Industrial
Waste Conference, Lafayette, IN, May 1-3, 1973, edited by Bell,
Purdue University Engineering Extension Series No. 14, Lafayette,
IN, 1973.
3. Heck, Robert P. Ill, "Munitions Plant Adsorption in Wastewater
Treatment," Industrial Waste, Vol. 24 (2), 35-39 (March/April).
4. EPA, State-of-the-Art: Military Explosives and Propellants
Production Industry: Volume III Wastewater Treatment.
EPA-600/2-76-213c.
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EXAMPLE 4 APPLICATION OP TECHNOLOGY-BASED STANDARDS
All cooling tower blovdown from an organic chemical facility is dis-
charged to the local POTV. To prevent scaling of the condensers during
recirculation of the cooling water, the facility uses chemical additives which
include chromium, zinc and possibly some priority pollutants. The blowdown
stream which contains these toxic pollutants has been determined to require a
discharge permit.
Cooling tower blowdown in the Steam Electric Power Generating category is
regulated by BAT and PSES limits for chromium, zinc and the 126 priority
pollutants (40 CFR 423.13 and 423.16). These limits are judged to be appli-
cable to the organic chemical manufacturing facility's discharge because the
practices and technologies of cooling tower maintenance at steam electric
power generating facilities and at organic chemicals manufacturing facilities
are similar.
6-24
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REFERENCES
1. RTECS Registry of Toxic Effects of Chemical Substances. 1981-1982.
National Institute of Safety and Health. Volumes 1-3.
2. Dean, J.A. Lange's Handbook, of Chemistry. 1985. McGraw-Hill.
Thirteenth Edition.
3. Sax, N.I. Dangerous Properties of Industrial Materials. 1979. Van
Nostrand Reinhold Company, Nev York.
4. Veast, R.C. CRC Handbook of Chemistry and Physics. 1975. CRC Press,
Cleveland OH. 56th Edition.
5. The Merck Index. Merck and Company, Inc. 1976. Rahway, NJ. Ninth
Edi tion.
6. Perry, R.H. and Chilton, C.H. Chemical Engineers' Handbook. 1973.
McGraw-Hill. Fifth Edition.
7. Shreve, R.N. and J.A. Brink, Jr. Chemical Process Industries. 1977.
McGraw-Hill. Fourth Edition.
8. Hawley, G.G. The Condensed Chemical Dictionary. 1981. Van Nostrand
Reinhold. Tenth Edition.
9. Lyman, W.J., W.F. Reehl, and D.H. Rosenblatt. Chemical Property
Estimation Methods. 1982. McGraw-Hill.
10. U.S. EPA. Fate of Priority Pollutants in Publicly Owned Treatment Works.
1982. EPA 440/1-82-303.
11. U.S. EPA. Chemical, Physical, and Biological Properties of Compounds
Present at Hazadous Waste Sites. 1985.
12. U.S. EPA. Aquatic Fate Process Data for Organic Priority Pollutants.
EPA 440/4-81-014.
13. U.S. EPA. .Health Assessment Document for Polychlorinated Dibenzo-P-
Dioxins. EPA 600/8-84-014F.
14. U.S. EPA. Superfund Public Health Evaluation Manual. ICF, Dec. 18, 1985.
15. U.S. EPA. Techniques for Evaluating Environmental Processes Associated
with Land Disposal of Specific Hazardous Wastes. 1982.
16. U.S. EPA. Chemical Emergency Preparedness Program; Chemical Profiles.
Dec. 1985, Vo. 1,2,3,
17. U.S. EPA. Numeric Criteria for Toxic Pollutants in State Water Quality
Standards, April 28, 1986
M-l
-------
18. "Facts and Figures." Chemical Engineering News. June 10, 1985. Volume
63. November 23, p.22-66.
19. U.S. EPA. Report to Congress on the Discharge of Hazardous Wastes to
Publicly Owned Treatment Works" 1986. EPA/530-SW-86-004.
20. Riddick, J.A. and W.B. Bunger. Organic Solvents, 1970, John Wiley and
Sons, Inc. Third Edition.
21. Patty, F.A. Industrial Hygiene and Technology, 1963, John Wiley and Sons,
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Standards applicable to PAH's, Dec. 10, 1986
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35. U.S. EPA. Handbook for Responding to Discharges of Sinking Hazardous
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of Hazardous Waste (proposed rule). 51 FR 114. Friday, June 13, 1986.
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51. Ajax, Robert L. and Wyatt, Susan R. (OAQPS). Information Memorandum -
Emissions of Trichloroethylene, Perchloroethylene, Methylene Chloride,
Ethylene Dichloride, Chloroform, Acrylonitrile, and Carbon Tetrachloride
from Publicly Owned Treatment Works. March 11, 1987. EPA Emission
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62. U.S. EPA, 1986. Background Document for Solvents to Support 40 CFR Part
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