U.S. Environmental Protection Agency
NPDES Permit Writers' Manual
U.S. Environmental Protection Agency
Office of Wastewater Management, Water Permits Division
State and Regional Branch
EPA-833-K-10-001 September 2010
NPDES
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United States Office of Water
Environmental Protection Washington, DC
Agency
United States
Environmental Protection Agency
National Pollutant Discharge Elimination
System (NPDES) Permit Writers' Manual
This guidance was developed by staff within the U.S. Environmental Protection Agency's (EPA's) Office of
Wastewater Management and addresses development of wastewater discharge permits under the National
Pollutant Discharge Elimination System (NPDES). NPDES permit development is governed by existing
requirements of the Clean Water Act (CWA) and the EPA NPDES implementing regulations. CWA provisions and
regulations contain legally binding requirements. This document does not substitute for those provisions or
regulations. Recommendations in this guidance are not binding; the permitting authority may consider other
approaches consistent with the CWA and EPA regulations. When EPA makes a permitting decision, it will make
each decision on a case-by-case basis and will be guided by the applicable requirements of the CWA and
implementing regulations, taking into account comments and information presented at that time by interested
persons regarding the appropriateness of applying these recommendations to the situation. This guidance
incorporates, and does not modify, existing EPA policy and guidance on developing NPDES permits.
EPA may change this guidance in the future.
Water Permits Division
Office of Wastewater Management
Washington, DC 20460
(4203)
www.epa.gov/npdes
EPA-833-K-10-001
September 2010
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Acknowledgements
David Hair and Pravin Rana, United States Environmental Protection Agency (EPA), Office of Water, Office of
Wastewater Management, Water Permits Division, Washington, DC, were the team leaders for the development and
production of this manual.
Many individuals assisted in this effort, including the following:
EPA, Office of Water, Office of Wastewater Management, Water Permits Division, Washington, DC
Mohammed Billah
Pat Bradley
Elaine Brenner
Jennifer Chan
Kawana Cohen
Juhi Saxena
Louis Eby
Jack Faulk
Sara Hilbrich
Jamie Hurley
Caitlin Kovzelove
Tom Laverty
Jennifer Molloy
Deborah Nagle
Jan Pickrel
Jane Rice, ORISE Intern
Greg Schaner
Martha Segall
George lifting
Kevin Weiss
Marcus Zobrist
EPA, Office of Water, Washington, DC
Bob Bastian, Office of Wastewater Management, Municipal Support Division
Tom Gardner, Office of Science and Technology, Standards and Health Protection Division
Meghan Hessenauer, Office of Science and Technology, Engineering and Analysis Division
Carey Johnston, Office of Science and Technology, Engineering and Analysis Division
Dick Reding, Office of Science and Technology, Engineering and Analysis Division
Maria Smith, Office of Science and Technology, Engineering and Analysis Division
Additional EPA Contributors
Robert Hargrove, Office of Enforcement and Compliance Assurance, Office of Federal Activities, Washington, DC
Robert Klepp, Office of Enforcement and Compliance Assurance, Office of Civil Enforcement,
Washington, DC
Doug Corb, Region 1 New England NPDES Municipal Permit Branch, Boston, MA
Jennifer Duckworth and Gregory Currey, Tetra Tech, Inc., Permits and Regulatory Support, Fairfax, VA managed
production and technical support for development of the manual.
Additional contributors from Tetra Tech, Inc. for development, design, and final production of this document include
Krista Carlson
Jim Collins
Chuck Durham
Steve Geil
Shari Goodwin
Cover and Exhibit 1-2 Photo Credits
1.
2.
3.
4.
5.
John Kosco
l-Hsin Lee
Gregory Mallon
Betty Peterson
Gregory Savitske
Peter Sherman
Kristin Schatmeyer
Jeff Strong
6.
7.
Natchez-Tennessee Tombigbee WaterwayPeter Cada, Tetra Tech, Inc.
Municipal Publicly Owned Treatment WorksOhio Environmental Protection Agency
Municipal Separate Storm Sewer SystemUSDA NRCS
Concentrated Animal Feeding OperationUSDA NRCS
Incidental Vessel DischargesSmithsonian Environmental Research Center,
National Ballast Information Clearinghouse
Non-Municipal (Industrial)EPA
Construction StormwaterBarry Tonning, Tetra Tech, Inc.
Combined Sewer OverflowEPA
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September 2010 NPDES Permit Writers' Manual
Contents
Introduction to the Manual vii
Purpose of this Manual vii
Publications Referenced viii
Legislative and Regulatory Citations viii
Electronic NPDES Information ix
CHAPTER1. Development of the Clean Water Act and the NPDES Program 1-1
1.1 History of Water Pollution Control in the United States 1-1
1.2 Evolution of the NPDES Program 1-3
1.3 NPDES Statutory Framework 1-5
1.3.1 Permit 1-5
1.3.2 Pollutant 1-6
1.3.3 Waters of the United States 1-6
1.3.4 Point Source 1-7
CHAPTER 2. Regulatory Framework and Program Areas of the NPDES Program 2-1
2.1 Regulatory Framework of the NPDES Program 2-1
2.2 Federal and State Responsibilities 2-2
2.2.1 State NPDES Program Authority 2-2
2.2.2 Roles and Responsibilities of the Federal and State Authorities 2-4
2.3 NPDES Program Areas 2-5
2.3.1 NPDES Program Areas Applicable to Municipal Sources 2-5
2.3.2 NPDES Program Areas Applicable to Non-Municipal Sources 2-10
2.4 Major/Minor Facility Designation 2-17
2.5 Growth and Change in the NPDES Program 2-17
CHAPTER 3. Overview of the NPDES Permitting Process 3-1
3.1 Types of Permits 3-1
3.1.1 Individual Permits 3-1
3.1.2 General Permits 3-1
3.2 Major Components of a Permit 3-2
3.3 Overview of the Development and Issuance Process for NPDES Individual Permits.... 3-3
3.4 Overview of the Development and Issuance Process for NPDES General Permits 3-5
CHAPTER 4. NPDES Permit Application Process 4-1
4.1 Who Applies for an NPDES Permit? 4-1
4.2 Application Deadlines 4-3
4.3 Application Forms and Requirements for Individual Permits 4-3
4.3.1 Form 1: General Information 4-5
4.3.2 Form2A: New and Existing POTWs 4-5
4.3.3 Form2S: New and Existing TWTDS 4-6
4.3.4 Form 2B: New and Existing Concentrated Animal Feeding Operations
(CAFOs) and Concentrated Aquatic Animal Production (CAAP) Facilities 4-7
4.3.5 Form 2C: Existing Manufacturing, Commercial, Mining, and Silvicultural
Discharges 4-8
4.3.6 Form 2D: New Manufacturing, Commercial, Mining, and Silvicultural
Discharges of Process Wastewater 4-8
4.3.7 Form2E: Manufacturing, Commercial, Mining, and Silvicultural Facilities
that Discharge Only Non-Process Wastewater 4-8
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September 2010 NPDES Permit Writers' Manual
4.3.8 Form 2F: Stormwater Discharges Associated with Industrial Activities 4-9
4.3.9 Stormwater Discharges Associated with Construction Activity 4-9
4.3.10 Stormwater Discharges from Small MS4s 4-11
4.3.11 Cooling Water Intake Structures 4-11
4.4 Requirements for NPDES General Permits 4-12
4.5 Application Review 4-13
4.5.1 The Complete Application 4-14
4.5.2 Common Omissions in Applications 4-14
4.5.3 The Accurate Application 4-16
4.6 Facility Information Review 4-17
4.6.1 Permit File Review 4-17
4.6.2 Facility Site Visits 4-19
4.7 Confidential Information 4-21
CHAPTERS. Technology-Based Effluent Limitations 5-1
5.1 Technology-based Effluent Limitations for POTWs 5-2
5.1.1 Secondary and Equivalent to Secondary Treatment Standards 5-2
5.1.2 Adjustments to Equivalent to Secondary Standards 5-4
5.1.3 Applying Secondary Treatment Standards, Equivalent to Secondary
Treatment Standards, and Adjusted Standards 5-6
5.2 Technology-Based Effluent Limitations for Industrial (Non-POTW) Dischargers 5-13
5.2.1 Effluent Guidelines 5-14
5.2.2 Applying Effluent Guidelines through NPDES Permits 5-23
5.2.3 Case-by-Case TBELs for Industrial Dischargers 5-44
CHAPTER 6. Water Quality-Based Effluent Limitations 6-1
6.1 Determine Applicable Water Quality Standards 6-2
6.1.1 Components of Water Quality Standards 6-3
6.1.2 Water Quality Standards Modifications 6-9
6.1.3 Water Quality Standards Implementation 6-11
6.2 Characterize the Effluent and the Receiving Water 6-12
6.2.1 Step 1: Identify Pollutants of Concern in the Effluent 6-13
6.2.2 Step 2: Determine Whether Water Quality Standards Provide for
Consideration of a Dilution Allowance or Mixing Zone 6-15
6.2.3 Step 3: Select an Approach to Model Effluent and Receiving Water
Interactions 6-16
6.2.4 Step 4: Identify Effluent and Receiving Water Critical Conditions 6-16
6.2.5 Step 5: Establish an Appropriate Dilution Allowance or Mixing Zone 6-20
6.3 Determine the Need for WQBELs 6-22
6.3.1 Defining Reasonable Potential 6-23
6.3.2 Conducting a Reasonable Potential Analysis Using Data 6-23
6.3.3 Conducting a Reasonable Potential Analysis without Data 6-30
6.4 Calculate Parameter-specific WQBELs 6-31
6.4.1 Calculating Parameter-specific WQBELs from Aquatic Life Criteria 6-31
6.4.2 Calculating Chemical-specific WQBELs based on Human Health Criteria
for Toxic Pollutants 6-35
6.5 Calculate Reasonable Potential and WQBELs for WET 6-36
6.5.1 Types of WET Tests 6-36
6.5.2 Expressing WET Limitations or Test Results 6-37
6.5.3 Determining the Need for WET Limitations 6-38
6.6 Antidegradation Review 6-40
6.6.1 Tier 1 Implementation 6-41
6.6.2 Tier 2 Implementation 6-41
6.6.3 TierS Implementation 6-42
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September 2010 NPDES Permit Writers' Manual
CHAPTER 7. Final Effluent Limitations and Anti-backsliding 7-1
7.1 Determining Final Effluent Limitations 7-1
7.2 Applying Anti-backsliding Requirements 7-2
7.2.1 Anti-backsliding Statutory Provisions 7-2
7.2.2 Anti-backsliding Regulatory Provisions 7-4
CHAPTER 8. Monitoring and Reporting Conditions 8-1
8.1 Establishing Monitoring Conditions 8-1
8.1.1 Purposes of Monitoring 8-2
8.1.2 Monitoring Location 8-2
8.1.3 Monitoring Frequency 8-5
8.1.4 Sample Collection 8-7
8.2 Additional Monitoring Requirements and WET Testing 8-9
8.2.1 Biosolids (Sewage Sludge) 8-9
8.2.2 Combined Sewer Overflows (CSOs) and Sanitary Sewer Overflows (SSOs).. 8-11
8.2.3 Stormwater Monitoring Considerations 8-11
8.2.4 WET Monitoring 8-12
8.3 Analytical Methods 8-13
8.4 Reporting Monitoring Results 8-14
8.5 Recordkeeping Requirements 8-14
CHAPTERS. Special Conditions 9-1
9.1 Special Conditions Potentially Applicable to Any Type of Discharger 9-1
9.1.1 Additional Monitoring and Special Studies 9-2
9.1.2 Best Management Practices (BMPs) 9-3
9.1.3 Compliance Schedules 9-8
9.2 Special Conditions for Municipal Facilities 9-9
9.2.1 The National Pretreatment Program 9-10
9.2.2 Biosolids (Sewage Sludge) 9-13
9.2.3 Combined Sewer Overflows (CSOs) 9-15
9.2.4 Sanitary Sewer Overflows (SSOs) 9-20
CHAPTER 10. Standard Conditions of NPDES Permits 10-1
10.1 Types of Standard Conditions 10-1
10.2 Other Standard Conditions 10-3
CHAPTER 11. NPDES Permit Administration 11-1
11.1 Other Federal Laws Applicable to NPDES Permits 11-1
11.1.1 Endangered Species Act 11-1
11.1.2 National Environmental Policy Act 11-2
11.1.3 National Historic Preservation Act Amendments 11-3
11.1.4 Coastal Zone Management Act 11-3
11.1.5 Wild and Scenic Rivers Act 11-3
11.1.6 Fish and Wildlife Coordination Act 11-4
11.1.7 Essential Fish Habitat Provisions 11-4
11.2 Documentation for Development of the Draft Permit 11-4
11.2.1 Administrative Record 11-8
11.2.2 Fact Sheets and Statements of Basis 11-8
11.3 Items to Address before Issuing a Final Permit 11-10
11.3.1 Public Notice 11-11
11.3.2 Public Comments 11-12
11.3.3 Public Hearings 11-13
11.3.4 Environmental Justice Considerations 11-14
11.3.5 EPA and State/Tribal Roles in Reviewing Draft Permits 11-14
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September 2010 NPDES Permit Writers' Manual
11.3.6 Schedule for Final Permit Issuance 11-15
11.4 Administrative Actions after Final Permit Issuance 11-16
11.4.1 Permit Appeals 11-16
11.4.2 Modification or Revocation and Reissuance of Permits 11-18
11.4.3 Permit Termination 11-20
11.4.4 Permit Transfer 11-21
11.5 Permit Compliance and Enforcement 11-21
11.5.1 Compliance Monitoring 11-22
11.5.2 Quarterly Noncompliance Reports 11-23
11.5.3 Enforcement 11-25
Appendix A. Acronyms, Abbreviations and Glossary A-1
A.1 Acronyms and Abbreviations A-1
A.2 Glossary A-4
Appendix B. Index to the CWA and NPDES Regulations B-1
B.1 Index to Sections of the CWA B-1
B.2 Index to NPDES Regulations B-3
Appendix C. Priority Pollutants C-1
Appendix D. New Source Dates by Effluent Guideline Category D-1
Exhibits
Exhibit 1-1 Important milestones of clean water program development 1-1
Exhibit 1-2 Common point source discharges of pollutants to waters of the United States 1-8
Exhibit2-1 Regulations related to the NPDES program 2-2
Exhibit2-2 Federal NPDES regulations (40 CFR Part 122) 2-3
Exhibit 2-3 Summary of federal and state/territorial/tribal roles in the NPDES permitting
program 2-5
Exhibit 2-4 NPDES program areas and applicable regulations 2-6
Exhibit 3-1 Permit components 3-3
Exhibit 3-2 Major steps to develop and issue NPDES individual permits 3-4
Exhibit 3-3 Major steps to develop and issue NPDES general permits 3-5
Exhibit 4-1 Effect of court decisions on § 122.3 4-2
Exhibit 4-2 When to apply for an NPDES permit 4-3
Exhibit 4-3 EPA application requirements for NPDES individual permits 4-4
Exhibit 4-4 Permit application review process 4-13
Exhibit 4-5 Considerations for an application to be complete 4-15
Exhibit 4-6 Example of required testing during application review 4-16
Exhibit 4-7 Considerations for an application to be accurate 4-18
Exhibit 5-1 Developing effluent limitations 5-1
Exhibit 5-2 Secondary treatment standards 5-2
Exhibit 5-3 Equivalent to secondary treatment standards 5-3
Exhibit 5-4 State-specific adjusted TSS requirements 5-5
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September 2010 NPDES Permit Writers' Manual
Exhibit 5-5 Steps to establish technology-based discharge limitations for POTWs 5-6
Exhibit 5-6 Effluent limitations calculated from secondary treatment standards 5-7
Exhibit 5-7 POTWmass based limitation calculation equation and example calculations 5-8
Exhibit 5-8 Summary of CWA technology levels of control 5-15
Exhibit 5-9 Visual example of TSS LTA, maximum daily limitation and average monthly
limitation 5-21
Exhibit 5-10 Steps for applying effluent guidelines to direct discharges 5-23
Exhibit 5-11 Table of existing point source categories (June 2010) 5-24
Exhibit 5-12 Examples of identifying applicable effluent guidelines using SIC codes 5-25
Exhibit 5-13 Examples of identifying the subcategory with the applicable effluent guidelines 5-27
Exhibit 5-14 Example of calculating mass-based effluent limitation from production-normalized
effluent guidelines 5-31
Exhibit 5-15 Example narrative requirement from the Concentrated Aquatic Animal Production
effluent guidelineSubpart A [§ 455.11 (a)] 5-33
Exhibit 5-16 Exclusion of wastewaters in metal finishing effluent guidelines 5-34
Exhibit 5-17 Excerpts from preamble to OCPSF effluent guidelines regarding applicability of
effluent guidelines 5-34
Exhibit 5-18 Building block approach for applying effluent guidelines 5-36
Exhibit 5-19 Example of tiered discharge limitations 5-38
Exhibit 5-20 Variances from effluent guidelines 5-40
Exhibit 5-21 Summary of factors considered when developing case-by-case TBELs 5-46
Exhibit 5-22 Tools for developing case-by-case TBELs using BPJ 5-48
Exhibit 6-1 Developing effluent limitations 6-1
Exhibit 6-2 Standards-to-permits process 6-2
Exhibit 6-3 Aquatic life criteria example: Cadmium (dissolved) 6-5
Exhibit 6-4 Human health criteria example: Dichlorobromomethane 6-7
Exhibit 6-5 Steps for characterizing the effluent and receiving water 6-13
Exhibit 6-6 Parts of a TMDL 6-14
Exhibit 6-7 Example of lognormal distribution of effluent pollutant concentrations and projection
of critical concentration (Cd) 6-18
Exhibit 6-8 Regulatory mixing zones for aquatic life criteria 6-21
Exhibit 6-9 Examples of maximum mixing zone sizes or dilution allowances under incomplete
mixing conditions by waterbody type 6-22
Exhibit 6-10 Steps of a reasonable potential analysis with available data 6-23
Exhibit 6-11 Simple mass-balance equation 6-24
Exhibit 6-12 Example of receiving water concentrations in an incomplete mixing situation
determined using an incomplete mixing water quality model 6-26
Exhibit 6-13 Mass-balance equation for reasonable potential analysis for conservative pollutant
under conditions of rapid and complete mixing 6-27
Exhibit 6-14 Example of applying mass-balance equation to conduct reasonable potential
analysis for conservative pollutant under conditions of rapid and complete mixing 6-28
Exhibit 6-15 Reasonable potential determination in an incomplete mixing situation 6-29
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September 2010 NPDES Permit Writers' Manual
Exhibit 6-16 Calculating parameter-specific WQBELs from aquatic life criteria 6-31
Exhibit 6-17 Example of applying mass-balance equation to calculate WLAs for conservative
pollutant under conditions of rapid and complete mixing 6-33
Exhibit 6-18 Example of lognormal distribution of effluent pollutant concentrations and
calculation ofWLA 6-34
Exhibit 6-19 Example of typical dilution series 6-36
Exhibit 6-20 Example of toxic units 6-37
Exhibit 6-21 Using the ACR 6-38
Exhibit 6-22 Example of mass-balance equation fora WET reasonable potential analysis 6-39
Exhibit 7-1 Developing effluent limitations 7-1
Exhibit 7-2 Application of anti-backsliding rules 7-5
Exhibit 7-3 Backsliding examples 7-6
Exhibit 8-1 Examples of specifying monitoring locations in permits 8-3
Exhibit 8-2 Visual interpretation of time-proportional composite monitoring 8-8
Exhibit 8-3 Visual interpretation of flow-proportional composite monitoring 8-8
Exhibit 8-4 Minimum requirements for sewage sludge monitoring, based on method of sludge
use or disposal 8-10
Exhibit 9-1 Example BMP plan requirement 9-6
Exhibit 9-2 Categories of CSO permitting conditions 9-17
Exhibit 9-3 Nine minimum CSO controls 9-17
Exhibit 9-4 Elements of the long-term CSO control plan 9-18
Exhibit 11-1 Other federal laws applicable to NPDES permits 11-1
Exhibit 11-2 Reasons for good documentation 11-5
Exhibit 11-3 Administrative process for EPA-issued NPDES permits 11-6
Exhibit 11-4 Typical administrative process for state-issued NPDES permits 11-7
Exhibit 11-5 Elements of the administrative records fora draft permit 11-8
Exhibit 11-6 Required elements of a fact sheet 11-9
Exhibit 11-7 Actions for which public notice is required 11-11
Exhibit 11-8 Contents of the public notice 11-12
Exhibit 11-9 Elements of the administrative records for a final permit 11-16
Exhibit 11-10 Causes for permit modification 11-19
Exhibit A-1 Acronyms and abbreviations A-1
Exhibit A-2 Glossary A-5
Exhibit B-1 Index to sections of the CWA B-1
Exhibit B-2 Index to NPDES regulations B-3
Exhibit C-1 Priority pollutants from 40 CFR Part 423, Appendix A C-1
Exhibit D-1 New source dates by effluent category D-2
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September 2010 NPDES Permit Writers' Manual
Introduction to the Manual
This manual reviews the statutory and regulatory framework of the National Pollutant Discharge
Elimination System (NPDES) program and examines technical considerations for developing NPDES
permits for wastewater discharges. The manual is designed, primarily, for new permit writers becoming
acquainted with the NPDES program and the process of permit writing, but can also serve as a reference
for experienced permit writers or anyone interested in learning about the legal and technical aspects of
developing NPDES permits. This manual replaces the 1996 U.S. EPA NPDES Permit Writers' Manual1
. which updated the 1993 Training Manual for NPDES Permit
Writers .
To assist the reader, acronyms and abbreviations are defined for the first use in each chapter and in
Appendix A of the manual. Endnotes are provided at the end of each chapter.
Purpose of this Manual
The purpose of this NPDES Permit Writers' Manual (manual) is to provide a general reference for
permitting authorities that outlines and explains the core elements of the NPDES permit program. The
core elements form the foundation of the NPDES program on which guidance for specific areas of the
program (e.g., stormwater, concentrated animal feeding operations) can be built. While the guidance for
these core program areas will be applicable in many cases, the U.S. Environmental Protection Agency
(EPA) recognizes that each EPA Regional Office or authorized state, territory, or tribe (hereafter state)
will tailor specific aspects of its NPDES permitting procedures to address state and local laws and site-
specific concerns and conditions.
The specific objectives and functions of this manual are as follows:
Provide an overview of the scope and the statutory and regulatory framework of the NPDES
program.
Describe the essential components of a permit and provide an overview of the permitting process.
Describe the different types of effluent limitations and the legal and technical considerations
involved in developing effluent limitations.
Describe the legal and technical considerations involved in developing other permit conditions
including
Monitoring and reporting requirements.
Special conditions.
Standard conditions.
Describe other permitting considerations including
- Variances.
- Anti-backsliding.
- Other applicable statutes.
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September 2010 NPDES Permit Writers' Manual
Explain the administrative process for issuing, modifying, revoking and terminating NPDES
permits.
This manual is not intended to be a standalone reference document. Rather, it establishes the framework
for NPDES permit development and should be supplemented, where necessary, by additional EPA and
state regulations, policy, and detailed guidance applicable to specific types of dischargers and
circumstances. To that end, this manual identifies and references relevant regulations, policy, and other
guidance documents throughout the text.
Publications Referenced
This manual provides links to publications available online that supplement the information in the
manual. All documents available electronically were accessed and available as of the date of this
manual's publication. Some documents are not available in an electronic format. In those instances,
readers should check the following sources to determine the availability of and to obtain printed copies of
the documents:
Office of Water Resource Center (OWRC)
OWRC is a contractor-operated facility providing document delivery, information/referral, and
reference services to public users and EPA staff interested in Office of Water Program
information
phone: 202-566-1729 or 800-832-7828, fax: 202-566-1736, e-mail:
.
EPA Library Services and Repositories
EPA's library services and repositories provide access to information about the environment and
related scientific, technical, management, and policy information. Library services
are delivered through the National Library Network
.
National Service Center for Environmental Publications (NSCEP)
NSCEP, formerly NCEPI, maintains and distributes EPA publications in hardcopy, CD ROM and
other multimedia formats. The publication inventory includes more than 7,000 titles
phone: 513-489-8190 or 800-490-9198, fax: 513-489-8695, e-mail: ncepimalfatone.net.
National Technical Information Service (NTIS)
NTIS is the largest central resource for government-funded scientific, technical, engineering, and
business related information covering more than 350 subject areas from more than 200 federal
agencies
phone: 703-605-6050 or 888-584-8332, fax: 703-605-6900, e-mail: customerservice@ntis.gov.
Legislative and Regulatory Citations
There are a number of different conventions used to cite legislation and regulations. In this manual, the
following conventions have been used:
When citing the United States Code, the abbreviation U.S.C. is used. The abbreviation is
preceded by the Title of the U.S.C. and then followed by the section number.
Example: 16 U.S.C. 1531 etseq. and 33 U.S.C. §§ 1251-1387.
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September 2010 NPDES Permit Writers' Manual
When citing the Clean Water Act, the abbreviation CWA is used. The abbreviation is followed by
the word section and then the section number.
Example: CWA section 402 and CWA section 402(o).
When citing the Code of Federal Regulations (CFR), the convention depends on the location of
the reference. For first references, the abbreviation CFR is preceded by the title number of the
CFR and followed either by the word Part (if it is a parta whole number) or the number of the
subsection (if it is a subpart/subsection). For subsequent references, the title and CFR are omitted
and just the word Part or the section symbol (§) is used.
Example: First citation: 40 CFR Part 136 or 40 CFR 122.44
Subsequent citations: Part 136 or § 122.44.
Almost all the regulatory citations in this manual are for Title 40 of the CFR (with the exception of the
other federal laws referenced in section 11.1 of this manual). Any other Titles are explicitly referenced
and in the format for the first regulatory citation (e.g., 50 CFR Part 402).
Electronic NPDES Information
Websites and electronically stored publications and data are available to help permit writers draft NPDES
permits. Tools have been created to assist permit writers with specific aspects of permit development and
are discussed in their respective sections. The electronic tools listed below apply to all aspects of permit
development and serve as valuable references for the permit writer.
NPDES Website and Resources
The Water Permits Division (WPD) within the EPA Office of Water (OW), Office of Wastewater
Management, has developed a comprehensive NPDES Website with technical and
regulatory information about the NPDES permit program, information on related programs and initiatives,
and documents published by WPD. Where applicable, this manual references the NPDES Website and
provides links to relevant documents on that site. This manual also references other EPA and non-EPA
websites that contain information that might be helpful to NPDES permit writers. Note, however, that
EPA is not responsible for information provided on websites outside the EPA Website .
WPD also has prepared several websites and other resources to help permit writers draft permits. This
manual references those websites and resources in the appropriate section of this manual.
Electronic Permitting Tools
Many EPA Regions and authorized states have developed tools to help them manage the permit issuance
process. Electronic permitting tools range from spreadsheets and word processing applications to
sophisticated Web-based systems that enable permitting authorities to manage their entire environmental
program. For example, some states have built systems that enable dischargers to electronically sign and
submit discharge reports; create, track, and store permit documents; and manage enforcement,
compliance, and inspections related to permits. As technologies continue to evolve, many permitting
authorities are likely to begin using more information technology applications to manage the process of
permitting.
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September 2010 NPDES Permit Writers' Manual
ICIS-NPDES
Together with OW, the Office of Enforcement and Compliance Assurance (OECA) is responsible for
oversight of implementation of the NPDES program. OW is responsible for the NPDES implementing
regulations and oversight of permit issuance by states and EPA Regions. OECA, along with its regional,
state, tribal and local counterparts, is responsible for tracking and maintaining enforcement and
compliance activities, monitoring and enforcement and compliance status of the regulated community,
and reviewing and evaluating program performance. OECA also maintains national data systems to
support program management and oversight of the NPDES program.
The Permit Compliance System (PCS), one of two national NPDES electronic databases, supports the
management and oversight of the NPDES program. Since the last modernization of PCS in 1985, the
NPDES program has evolved significantly to include additional program requirements, such as the
NPDES program for stormwater and implementation of the Combined Sewer Overflow Control Policy.
Because of limitations to PCS, OECA is working to phase out this system and move to a more modern
data management system described below.
The Integrated Compliance Information System for NPDES permits (ICIS-NPDES)
. the successor to PCS, provides an updated system that enables national program
management and oversight activities such as
Permit tracking and management.
Compliance monitoring.
NPDES program management.
Enforcement actions.
ICIS-NPDES is a Web-based system with an electronic database capable of handling the large amount of
data generated by and about the NPDES program. Section 11.5.1.1 of this manual provides more
information on ICIS-NPDES as it relates to NPDES permit compliance.
Hyperlinks in this Document
Where a website provides supplementary information or is referenced in this manual, the actual site or
higher level site address appears in the symbols <> so that readers will have a reference to the address
even in a printed version of this document. In the electronic version of the manual, the text in carats is
also the hyperlink to the referenced website. Care has been taken to provide the correct Web addresses
and hyperlinks; however, these references can change or become outdated after this manual's publication.
1 U.S. Environmental Protection Agency. 1996. U.S. EPA NPDES Permit Writers'Manual. EPA-833-B-96-003. U.S.
Environmental Protection Agency, Office of Water, Washington, DC. . Separate
sections of this document are also available on the NPDES Website by going to , clicking on Publications
and entering NPDES Permit Writers' Manual in the Search box.
2 U.S. Environmental Protection Agency. 1993. Training Manual for NPDES Permit Writers. EPA-833-B-93-003. U.S.
Environmental Protection Agency, Office of Wastewater Management, Washington, DC.
.
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CHAPTER 1. Development of the Clean Water Act and the
NPDES Program
This chapter presents an overview of the history of water pollution control in the United States and the
evolution and accomplishments of the National Pollutant Discharge Elimination System (NPDES)
Program.
1.1 History of Water Pollution Control in the United States
Major water pollution control legislation in the United States dates back to the end of the 19th century.
Exhibit 1-1 presents a summary of key legislative and executive actions in the history of clean water
program development in the United States.
Exhibit 1-1 Important milestones of clean water program development
1899 Rivers and Harbors Act
1948 Federal Water Pollution Control Act (FWPCA)
1965 Water Quality Act
1970 Executive Order-U.S. Environmental Protection Agency (EPA) established
1970 Refuse Act Permit Program (RAPP)
1972 FWPCA Amendments
1977 Clean Water Act (CWA)
1987 Water Quality Act (WQA) j
The first major water pollution control statute was the 1899 Rivers and Harbors Act, which established
permit requirements to prevent unauthorized obstruction or alteration of any navigable water of the
United States. That act focused on navigation rather than water quality.
The 1948 Federal Water Pollution Control Act (FWPCA) initiated the federal government's
involvement in water pollution control for public health protection. The act allotted funds to state and
local governments for water pollution control and emphasized the states' role in controlling and
protecting water resources with few federal limitations or guidelines. The act, however, did charge the
U.S. Surgeon General with developing comprehensive programs to eliminate or reduce the pollution of
interstate waters.
Over the next two decades, Congress became increasingly interested in the problem of water quality
degradation. From 1956 through 1966, it enacted four major laws to strengthen the federal role in water
pollution control, including the FWPCA Amendments of 1956 and the FWPCA Amendments of 1961.
Those statutes focused primarily on providing funding to municipalities to construct wastewater treatment
plants.
Just a few years later, Congress further strengthened federal water pollution control laws by enacting the
1965 Water Quality Act. This law created the Federal Water Pollution Control Administration and
Chapter 1: Development of the Clean Water Act and the NPDES Program 1-1
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represented a major regulatory advancement in water pollution control by requiring states to develop
water quality standards for interstate waters by 1967. The Water Quality Act also called for states to
quantify the amount of pollutants that each discharger could release without exceeding the water quality
standards (i.e., pollutant loadings). Despite escalating public concern and increased public spending, only
about half of the states developed water quality standards by 1971. Furthermore, enforcement of the
federal statute was minimal because the regulatory agencies had to demonstrate a direct link between a
discharge and a health or water quality problem, and the scientific data to make such demonstrations were
often lacking. Finally, there were no criminal or civil penalties for violations of statutory requirements.
Growing concern about the environment prompted President Nixon to form the U.S. Environmental
Protection Agency (EPA) in 1970 to enforce environmental compliance and consolidate federal
pollution control activities. That year, the President also created the Refuse Act Permit Program
(RAPP) through Executive Order 11574 and under the authority of section 13 of the 1899 Rivers and
Harbors Act (a section also known as the Refuse Act). This new permitting program was focused on
controlling industrial water pollution. EPA and the U.S. Army Corps of Engineers (Corps) would prepare
the program requirements and the Corps would administer the program. EPA was tasked with developing
guidelines on effluent quality for 22 different categories of sources. A discharger would apply for a
permit, and the Corps would ask EPA if the proposed effluent levels were consonant with state water
quality standards and with the newly developed guidelines on effluent quality. States would be asked to
examine permit applications and advise EPA whether existing or proposed treatment processes would
ensure that established water quality standards would be met. EPA would review the state's response for
interstate waters and instruct the Corps whether to issue the permit. However, the U.S. District Court for
the District of Columbia struck down RAPP (Kalur v. Resor, Civ. Action No. 1331-71 [D.D.C. Dec. 21,
1971]) because the program would allow the issuance of permits to discharge refuse to non-navigable
tributaries of navigable waterways, which the Court said exceeded the authority given in the Act, and
because the regulations implementing the program did not require compliance with certain procedural
requirements of the National Environmental Policy Act.
Because of the perceived need for a discharge permit program, and to rectify the problems encountered in
earlier water pollution control legislation, Congress enacted the FWPCA Amendments of 1972. This
legislation, which was passed over a Presidential veto in November 1972, provided a comprehensive re-
codification and revision of past federal water pollution control law. The 1972 amendments marked a
distinct change in the philosophy of water pollution control in the United States and marked the beginning
of the present water programs, including the NPDES permit program. Under those amendments, the
federal government assumed a major role in directing and defining water pollution control programs. In
establishing the basis for clean water programs, Congress sought a balance between economics
(considering both the costs and benefits of cleanup) and ecology (setting deadlines and ambitious
requirements for reducing discharges and restoring water quality).
The FWPCA Amendments of 1972 established a series of goals in section 101. Perhaps the most notable
goal was that the discharge of pollutants into navigable waters be eliminated by 1985. Although that goal
remains unmet, it underlies the CWA approach to establishing the technology standards that are
implemented through technology-based effluent limitations (TBELs) in NPDES permits. The FWPCA
Amendments of 1972 also set an interim goal of achieving, "water quality [that] provides for the
protection and propagation offish, shellfish, and wildlife and provides for recreation in and on the water"
by July 1, 1983. That goal is commonly referred to as thefishable, swimmable goal of the act and is one
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of the factors that states must consider in the development of their water quality standards. The water
quality standards are implemented in NPDES permits through water quality-based effluent limitations
(WQBELs). By prohibiting the discharge of a pollutant or pollutants from a point source to waters of the
United Statesexcept as in compliance with the statute, the FWPCA Amendments of 1972 also
established the important principle that the discharge of pollutants to navigable waters is not a right.
Since 1972, the FWPCA has been further amended on several occasions, including the 1977 Clean
Water Act (CWA), which is now the name for the statute, and the 1987 Water Quality Act (WQA).
Both of these statutes are discussed further in section 1.2 below with regard to their impact on the
evolution of the NPDES program. Exhibit B-l, Index to Sections of the CWA, in Appendix B of this
document matches the key sections of the CWA to their appropriate reference in the United States Code
(U.S.C.). This information is at U.S.C.. Title 33 (Navigation and Navigable Waters'). Chapter 26 (Water
Pollution Prevention and Control). 1251-1387 (33 U.S.C. §§ 1251-1387)
.
1.2 Evolution of the NPDES Program
Section 402 of Title IV of the FWPCA, Permits and Licenses, created today's system for permitting
wastewater discharges, known as the NPDES program. Under the requirements of the program, a point
source may be authorized to discharge pollutants into waters of the United States by obtaining a permit.
Section 1.3 below discusses this basic statutory framework in detail. A permit provides two types of
control: technology-based limitations (based on the technological and economic ability of dischargers in
the same category to control the discharge of pollutants in wastewater) and water quality-based
limitations (to protect the quality of the specific waterbody receiving the discharge).
The FWPCA Amendments of 1972 established several important requirements and deadlines. Municipal
facilities were required to meet secondary treatment standards by July 1, 1977. Industrial facilities were
required to meet two levels of technology standards: Best Practicable Control Technology Currently
Available (BPT) and Best Available Technology Economically Achievable (BAT), which would bring
them further toward the goal of eliminating the discharge of all pollutants. [CWA section 301 (b)(2)(A)].
Compliance deadlines for BPT and BAT were established as of July 1, 1977, and July 1, 1983,
respectively.
In addition to BPT and BAT requirements for industrial categories, the 1972 FWPCA Amendments
established new source performance standards (NSPS) or best available demonstrated control technology
including where practicable a standard permitting no discharge of pollutants [CWA section 306(a)]. The
Legislative History indicates that Congress believed that technologies would be more affordable for new
dischargers who could plan control technologies at the design phase. The standards represent state-of-the-
art control technologies for new sources because the permittees have the opportunity to install the most
efficient production processes and the latest in treatment technologies during construction. NSPS are
effective on the date the facility begins operation, and the facility must demonstrate compliance within
90 days of start-up.
EPA tried to set national, uniform effluent limitations guidelines and standards (effluent guidelines) as a
basis for technology-based limitations; however, most effluent guidelines were not in place when the first
set of permits was issued between 1973 and 1976. About 75 percent of the first round permits were issued
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under a section of the act that allows a permit writer to use his or her best professional judgment to
establish case-by-case limitations. Using that approach, a single permit writer developed effluent
limitations for a specific facility using his or her knowledge of the industry and the specific discharge,
rather than using a set of national standards and limitations developed by EPA for the entire industry.
This first round of permitting focused on conventional pollutants, which generally are found in sanitary
waste from households, businesses, and industries. CWA section 304(a)(4) and Title 40 of the Code of
Federal Regulations (CFR) 401.16 designate the conventional pollutants with oil and grease added to
§ 401.16 in 1979. The following are formally designated as conventional pollutants:
Five-day Biochemical Oxygen Demand (BOD5).
Total Suspended Solids (TSS).
pH.
Fecal Coliform.
Oil and Grease.
The 1972 FWPCA Amendments, however, also required that EPA publish a list of toxic pollutants within
90 days and propose effluent standards for those pollutants 6 months later. EPA was not able to meet
those requirements because of the lack of information on treatability. The Natural Resources Defense
Council (NRDC) sued EPA, resulting in a court supervised consent decree (NRDC et al. v. Train,
8 E.R.C. 2120, DDC 1976) that identified the following:
Toxic (priority) pollutants to be controlled.
Primary industries for technology-based control.
Methods for regulating toxic discharges through the authorities of the FWPCA Amendments.
The provisions of the consent decree were incorporated into the framework of the 1977 FWPCA
Amendments, formally known as the CWA. This statute shifted the emphasis of the NPDES program
from controlling conventional pollutants to controlling toxic pollutant discharges. CWA section 307(a)(l)
required EPA to publish a list of toxic pollutants or combination of pollutants. Those pollutants often are
called the priority pollutants and are listed in § 401.15. The terms toxic pollutant and priority pollutant
are used interchangeably throughout this document.
CWA section 307(a) originally identified 65 toxic pollutants and classes of pollutants for 21 major
categories of industries (known as primary industries). That list was later further defined as the current
list of 126 toxic pollutants. The priority pollutants are listed in Appendix C of this document and in
Appendix A of Part 423. Note that the list goes up to 129; however, there are only 126 priority pollutants
because 017, 049, and 050 were deleted.
The 1977 CWA adjusted technology standards to reflect the shift toward control of toxics, clarified and
expanded the concept of BAT controls, created a new level of control for conventional pollutants, and
made changes to strengthen the industrial pretreatment program. The 1977 law created a new pollutant
category, nonconventional pollutants, that included pollutants (such as chlorine and ammonia) not
specifically categorized as conventional or toxic. The CWA clarified that BAT covers both toxic and
nonconventional pollutants, extended the compliance deadline for BAT for toxic pollutants to July 1,
1984, established a three-year deadline for compliance with BAT for newly listed toxics, and gave
industries until as late as July 1, 1987 to meet BAT requirements for nonconventional pollutants. In
addition, conventional pollutants, controlled by BPT and BAT in the first round of permitting, were now
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subject to a new level of control termed Best Conventional Pollutant Control Technology (BCT). The
CWA established a compliance deadline for BCT of July 1, 1984. BCT was not an additional
performance standard, but replaced BAT for the control of conventional pollutants. Finally, among other
changes, the 1977 CWA authorized EPA to approve local pretreatment programs and required authorized
states to modify their programs to provide for local pretreatment program oversight.
The 1977 CWA recognized that the technology-based limitations were not able to prevent the discharge
of toxic substances in toxic amounts in all waterways. To complement its work on technology-based
limitations, EPA initiated a national policy in February 1984 to control toxics using a water quality
approach. On February 4, 1987, Congress amended the CWA with the 1987 WQA that outlined a strategy
to accomplish the goal of meeting state water quality standards. The 1987 WQA required all states to
identify waters that were not expected to meet water quality standards after technology-based controls on
point source were imposed. Each state then had to prepare individual control strategies to reduce toxics
from point and nonpoint sources to meet the water quality standards. Among other measures, those plans
were expected to address control of pollutants beyond technology-based levels.
The 1987 WQA further extended the compliance deadline for BAT- and BCT-based effluent limitations,
this time to a new deadline of March 31, 1989. The 1987 WQA also established new schedules for issuing
NPDES permits to industrial and municipal storm water dischargers. In addition to meeting water quality-
based standards, industrial stormwater discharges must meet the equivalent of BAT and BCT effluent
quality standards. Municipal separate storm sewer systems (MS4s) were required to have controls to
reduce pollutant discharges to the maximum extent practicable (MEP), including management practices,
control techniques and system design and engineering methods, and such other provisions as the
Administrator deems appropriate for the control of such pollutants [CWA section 402(p)(3)(B)]. The
1987 WQA also required EPA to identify toxics in sewage sludge and establish numeric limitations to
control such toxics. A statutory anti-backsliding requirement in the WQA specified the circumstances
under which an existing permit can be modified or reissued with less stringent effluent limitations,
standards, or conditions than those already imposed.
Since 1987, there have been minor revisions to the CWA (e.g., Combined Sewer Overflow program
requirements). However, the basic structure of the NPDES program remains unchanged from the
framework established in the 1972 FWPCA Amendments.
1.3 NPDES Statutory Framework
As noted in section 1.2 above, under the NPDES program any point source that discharges or proposes to
discharge pollutants into waters of the United States is required to obtain an NPDES permit.
Understanding how each of these terms (i.e., permit, pollutant, waters of the United States, and point
source) is defined is the key to defining the scope of the NPDES program.
1.3.1 Permit
A permit is a license, issued by the government to a person or persons granting permission to do
something that would otherwise be illegal without the permit. An NPDES permit typically is a license for
a facility to discharge a specified amount of a pollutant into a receiving water under certain conditions;
however, NPDES permits can also authorize facilities to process, incinerate, landfill, or beneficially use
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biosolids (sewage sludge). A discharger does not have a right to receive a permit, and permits may be
revoked for cause such as noncompliance with the conditions of the permit.
1.3.2 Pollutant
The term pollutant is defined in CWA section 502(6) and § 122.2. The statute defines pollutant very
broadly and includes any type of industrial, municipal, or agricultural waste (including heat) discharged
into water. For regulatory purposes, pollutants are grouped into three categories under the NPDES
program: conventional, toxic, and nonconventional.
Conventional pollutants are those defined in CWA section 304(a)(4) and § 401.16 (BOD5, TSS,
fecal coliform, pH, and oil and grease).
Toxic (priority) pollutants are those defined in CWA section 307(a)(l) (and listed in § 401.15
and Appendix A of Part 423) and include 126 metals and manmade organic compounds (see
Exhibit C-l in Appendix C of this document).
Nonconventional pollutants are those that do not fall under either of the above categories
(conventional or toxic pollutants) and include parameters such as chlorine, ammonia, nitrogen,
phosphorus, chemical oxygen demand (COD), and whole effluent toxicity (WET).
Sewage from vessels and, under certain conditions, water, gas, or other material injected into wells to
facilitate production of oil or gas or water derived in association with oil and gas production and disposed
of in a well are specifically excluded from the definition of pollutant under the NPDES program.
1.3.3 Waters of the United States
The CWA regulates discharges to navigable waters. CWA section 502(7) defines navigable waters as
"waters of the United States, including the territorial seas." NPDES regulations define waters of the
United States to mean,
Waters that are currently used, were used in the past, or may be susceptible to use in interstate or
foreign commerce, including waters subject to the ebb and flow of the tide.
Interstate waters including interstate wetlands.
Other waters that could affect interstate or foreign commerce.
Impoundments of waters of the United States.
Tributaries of the above categories of waters.
Territorial seas.
Wetlands adjacent to other waters (except wetlands themselves) in the above categories.
Wetlands are further defined in § 122.2. In addition, the definition of waters of the United States contains
exclusions for waste treatment systems (other than certain cooling ponds) designed to meet the
requirements of the CWA and also for prior converted croplands, which is mostly relevant to the CWA
section 404 permitting program administered by the Corps.
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Waters of the United States covers a broad range of surface waters. The CWA does not give EPA the
authority to regulate ground water quality through NPDES permits. If a discharge of pollutants to ground
water reaches waters of the United States, however, it could be a discharge to the surface water (albeit
indirectly via a direct hydrological connection, i.e., the ground water) that needs an NPDES permit.
The scope of waters of the United States has been the subject of several U.S. Supreme Court cases (the
most recent as of the time of publication of this manual being a decision from 2006 in the combined
Rapanos/Carabell wetland cases) and numerous lower court cases. The court cases often have been
difficult to interpret, resulting in much litigation and an evolving understanding of the exact scope of
waters subject to CWA jurisdiction. Also, permit writers should keep in mind that discharges through
non-jurisdictional features that reach waters of the United States may need a permit even if the discharge
is not directly to a jurisdictional waterbody. EPA Regional wetlands staff have significant expertise in
jurisdictional issues related to the scope of waters of the United States. Some Regions have interoffice
teams to address jurisdictional issues that come up in the different CWA programs. In addition, guidance
on waters of the United States is on EPA's Office of Wetlands. Oceans, and Watersheds Website
.
1,3,4
Pollutants can enter water via a variety of pathways including agricultural, domestic and industrial
sources. For regulatory purposes, these sources generally are categorized as either point sources or
nonpoint sources. The term point source is defined in CWA section 502(14) and § 122.2 to include any
discernible, confined, and discrete conveyance from which pollutants are or may be discharged. Point
source discharges include discharges from publicly owned treatment works (POTWs), industrial process
wastewater discharges, runoff conveyed through a storm sewer system, and discharges from concentrated
animal feeding operations (CAFOs), among others (see Exhibit 1-2). Return flows from irrigated
agriculture and agricultural storm water runoff specifically are excluded from the definition of a point
source.
Pollutant contributions to waters of the United States may come from both direct and indirect discharges.
Direct discharge (which is synonymous with discharge of a pollutant) is defined by the NPDES
regulations at § 122.2 to include any addition of any pollutant or combination of pollutants to a water of
the United States from any point source. An indirect discharger is defined as, "a nondomestic discharger
introducing pollutants to a POTW." Under the national program, NPDES permits are issued only to direct
dischargers. The National Pretreatment Program controls industrial and commercial indirect dischargers
(for more on pretreatment, see section 2.3.1.2 of this manual).
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Exhibit 1-2 Common point source discharges of pollutants to waters of the United States
Municipal
(Publicly Owned Treatment Works)
Combined Sewer
Overflow
Municipal Separate
Storm Sewer System
Concentrated Animal
Feeding Operation
Non-Municipal (Industrial)
Process/Non-process Wastewater
and Stormwater
Incidental Vessel
Discharges
1-8
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CHAPTER 2. Regulatory Framework and Program Areas
of the NPDES Program
This chapter discusses the regulatory framework of the National Pollutant Discharge Elimination System
(NPDES) program, identifies the types of activities regulated under the NPDES program, describes the
roles and responsibilities of federal and state governments, and presents the program areas that address
the various types of regulated activities.
2.1 Regulatory Framework of the NPDES Program
Chapter 1 discussed how Congress, in Clean Water Act (CWA) section 402, required the U.S.
Environmental Protection Agency (EPA) to develop and implement the NPDES permit program. While
Congress' intent was established in the CWA, EPA was required to develop specific regulations to carry
out the congressional mandate. The regulations developed by EPA to implement and administer the
NPDES program primarily are in Title 40 of the Code of Federal Regulations (CFR) Part 122
.
The CFR is an annual codification of the general and permanent rules published in the Federal Register
(FR) by the executive departments and agencies of the federal government. The CFR is divided into 50
titles that represent broad areas subject to federal regulation. Title 40 covers protection of the
environment. The FR is a legal publication that contains federal agency regulations; proposed rules and
notices; and executive orders, proclamations and other presidential documents. The National Archives
and Records Administration, an independent federal agency responsible for managing all federal records,
publishes the FR and CFR. The text of all final regulations is found in the CFR. The background and
implementation information related to these regulations, however, are found in the preamble to the
regulations contained in the FR. This information is important to permit writers because it explains the
legal, technical, and scientific bases on which regulatory decisions are made.
Exhibit 2-1 lists regulations in 40 CFR that are related to the NPDES program, and Exhibit 2-2 is an
outline of the federal NPDES regulations from Part 122. The regulations at § 123.25 should be referenced
for information applicable to state NPDES programs. Exhibit B-2 in Appendix B of this document is an
Index to NPDES Regulations that provides regulatory citations by topic area.
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Exhibit 2-1 Regulations related to the NPDES program
Regulation (40 CFR) Subject
Part 121 State certification
Part 122 The federal NPDES permit program
Part 123 State program requirements
Part 124 Procedures for decision making
Part 125 Technology standards
Part 129 Toxic pollutant effluent standards
Part 130 Water quality planning and management
Part 131 Water quality standards
Part 133 Secondary treatment regulations
Part 135 Citizen suits
Part 136 Analytical procedures
Part 257 State sludge disposal regulations
Part 401 General provisions for effluent limitations guidelines and standards (effluent guidelines)
Part 403 General pretreatment regulations
Parts 405-471 Effluent guidelines
Part 501 State sewage sludge management program requirements
Part 503 Standards for use or disposal of sewage sludge
2.2 Federal and State Responsibilities
This section discusses the relationship between federal and state governments in the administration of the
NPDES program and the process by which a state can become authorized.
2.2.1
EPA may authorize qualified state, territorial, or tribal government agencies to implement all or parts of
the NPDES program. States, territories, or tribes (hereafter states) are authorized through a process
defined by the CWA section 402(b) and NPDES regulations Part 123. A state wanting to be authorized to
administer the NPDES program submits to EPA a letter from the governor requesting review and
approval of its program submission, a Memorandum of Agreement (MOA), a Program Description, a
Statement of Legal Authority (also known as an Attorney General's Statement or AG Statement), and the
underlying state laws and regulations. EPA determines whether the package is complete within 30 days of
receipt. Within 90 days of receipt, EPA renders a decision to approve or disapprove the program. The
time for review can be extended by agreement. The process of authorization includes a public review and
comment period, and a public hearing.
States may apply for the authority to issue one or more of the following five types of NPDES
authorization:
NPDES Base Program for individual municipal and industrial facilities.
General Permit Program.
Pretreatment Program.
Federal Facilities Program.
Biosolids (Sewage Sludge) Program.
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Exhibit 2-2 Federal NPDES regulations (40 CFR Part 122)
Sub part A-Definitions and General Program Requirements
§122.1 Purpose and scope
§ 122.2 Definitions
§ 122.3 Exclusions
§ 122.4 Prohibitions
§122.5 Effect of a permit
§ 122.6 Continuation of expiring permits
§ 122.7 Confidentiality of information
Sub part B-Permit Application and Special NPDES Program Requirements
§ 122.21 Applications
§ 122.22 Signatories to permit applications and reports
§ 122.23 Concentrated animal feeding operations
§ 122.24 Concentrated aquatic animal production
§122.25 Aquaculture projects
§122.26 Stormwater discharges
§ 122.27 Silviculture activities
§122.28 General permits
§ 122.29 New sources and new dischargers
§ 122.30-122.37 MS4s
Sub part C-Permit Conditions
§ 122.41 Standard conditions applicable to all permits
§ 122.42 Standard conditions applicable to specified categories of permits
§ 122.43 Establishing permit conditions
§ 122.44 Establishing limitations, standards, and other permit conditions
(a) Technology basis
(b) Other basis (not WQ)
(c) Reopeners
(d) Water quality basis
(e) Toxic (priority) pollutants
(f) Notification levels
(g) 24 Hour reporting
(h) Duration of permits
(i) Monitoring
(j) Pretreatment program
§ 122.45 Calculating limitations
(a)
(b)
(c)
(d)
(e)
§ 122.46
§ 122.47
§ 122.48
§ 122.49
§ 122.50
Outfalls and discharge points
Production basis
Metals
Continuous discharges
Non-continuous discharges
(k) Best management practices (BMPs)
(I) Anti-backsliding
(m) Privately owned treatment works
(n) Grants
(o) Sewage sludge
(p) Coast Guard
(q) Navigation
(r) Great Lakes
(s) Qualifying programs
(f) Mass limitations
(g) Pollutants in intake water
(h) Internal waste streams
(i) Discharge into wells, into publicly owned
treatment works or by land application
Duration of permits
Schedules of compliance
Requirements for recording and reporting of monitoring results
Consideration under federal law
Disposal into wells, into publicly owned treatment works or by land application
Sub part D-Transfer, Modification, Revocation and Reissuance, and Termination of Permit
§ 122.61 Transfer of permits
§ 122.62 Modification or revocation and reissuance of permits
§ 122.63 Minor modifications of permits
§ 122.64 Termination of permits
Chapter 2: Regulatory Framework and Program Areas of the NPDES Program
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A state can receive authorization for one or more of the NPDES program components. For example, a
state might receive authorization for the NPDES Base Program, General Permit Program, and
Pretreatment Program, but not the Federal Facilities Program or Biosolids Program. In such a case, EPA
continues to issue permits to federal facilities (e.g., facilities on military installations, federal lands) for
discharges originating within the state and continues to implement the Biosolids Program. (Section 2.2.2
below provides additional discussion of Biosolids Program implementation.)
If EPA approves a program, the state assumes permitting authority in lieu of EPA. All new permit
applications would then be submitted to the state agency for NPDES permit issuance. Certain permits
issued before authorization might continue under EPA administration as set forth in the MOA. Even after
a state receives NPDES authorization, EPA continues to issue NPDES permits on tribal lands within the
boundaries of the state (if the tribe is not administering its own approved NPDES program). Following
authorization, EPA also continues its national program management responsibilities by ensuring that state
programs meet applicable federal requirements. If EPA disapproves the program, EPA remains the
permitting authority for that state.
The State Program Status Website provides the current authorization
status for the states.
2.2.2 Roles and Responsibilities of the Federal and State Authorities
Until a state program is authorized, EPA is the permitting authority that issues all permits, conducts all
compliance and monitoring activities, and enforces all program requirements.
As noted above, if a state has only partial authority, EPA will implement the other program activities. For
example, where a state has an approved NPDES program but has not received EPA approval of its state
sewage sludge management program, the EPA Region is responsible for including conditions to
implement the Part 503 Standards for the Use or Disposal of Sewage Sludge in permits issued to
treatment works treating domestic sewage (TWTDS) in that state. EPA could issue a separate permit with
the applicable sewage sludge standards and requirements, or collaborate with the state on joint issuance of
NPDES permits containing the Part 503 sewage sludge standards. The same process also applies where a
state has not received approval of its pretreatment program or federal facilities program. One exception to
that process is where an NPDES-authorized state is not approved to implement the general permit
program. In such cases, EPA may not issue a general permit in that state as clarified in the memorandum
EPA 's Authority to Issue NPDES General Permits in Approved NPDES States1
.
Once a state is authorized to issue permits, EPA generally is precluded from issuing permits in the state;
however, EPA must be provided with an opportunity to review certain permits and may formally object to
elements that conflict with federal requirements. If the permitting agency does not satisfactorily address
the points of objection, EPA will issue the permit directly. Once a permit is issued through a government
agency, it is enforceable by the approved state and federal agencies (including EPA) with legal authority
to implement and enforce the permit. Private citizens may also bring a civil action in federal court against
an alleged violator or against the EPA Administrator for alleged failure to enforce NPDES permit
requirements. Exhibit 2-3 presents a summary of federal and state roles before and after program
authorization.
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Exhibit 2-3 Summary of federal and state/territorial/tribal roles in the
NPDES permitting program
Before state/territorial/tribal program approval:
EPA issues permits
EPA conducts compliance and monitoring activities
EPA enforces
State/territory/tribe reviews permits and grants CWA section 401 certification
After state/territorial/tribal program approval:
State/territory/tribe issues permits
State/territory/tribe conducts compliance and monitoring activities
State/territory/tribe enforces
EPA provides administrative, technical and legal support
EPA ensures state program meets federal requirements
EPA offers NPDES program training
EPA oversees grants to states (e.g., CWA section 106)
EPA reviews permits and, as necessary, comments or objects
EPA oversees and, as necessary, assumes enforcement of permits
2.3 NPDES Program Areas
NPDES permittees can be broadly classified as municipal (publicly owned treatment works [POTWs] and
related discharges) and non-municipal facilities. Federal facilities fall into the broader category of non-
municipal facilities. Within those broad categories, there might also be specific types of activities that are
subject to unique programmatic requirements in the NPDES regulations. Exhibit 2-4 provides an
overview of the different activities related to municipal and non-municipal sources; identifies the NPDES
program areas that address these activities; and identifies the applicable regulations for each NPDES
program area.
2.3.1 to
The NPDES regulations establish technology-based effluent requirements applicable to discharges from
POTWs. In addition to effluent requirements, the NPDES regulations establish other programmatic
requirements applicable to other POTW activities (e.g., sewage sludge disposal and management,
stormwater discharges from the treatment plant site) or activities that may be conducted by a municipality
(e.g., municipal separate storm sewer systems, combined sewer overflows). A description of those
programs and how they relate to NPDES permits is provided in the following sections.
2.3.1.1 (POTWs)
The federal regulations at § 403.3 define a POTW as a treatment works (as defined in CWA section 212)
that is owned by a state or municipality [as defined in CWA section 502(4)]. The definition includes any
devices and systems used in the storage, treatment, recycling, and reclamation of municipal sewage or
industrial wastes of a liquid nature. It also includes sewers, pipes, and other conveyances only if they
convey wastewater to a POTW. Finally, the term also means the municipality that has the jurisdiction
over the indirect discharges to and the discharges from the treatment works. Federally owned treatment
works, privately owned treatment works, and other treatment plants not owned by a state or municipality
are not considered POTWs.
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Source
Exhibit 2-4 NPDES program areas and applicable regulations
Program areas
Applicable regulations
(40 CFR)
Municipal
Municipal (POTWs) effluent discharges
Indirect non-municipal discharges (Pretreatment)
Biosolids (sewage sludge) use and disposal
Combined sewer overflow (CSO) discharges
Sanitary sewer overflow (SSO) discharges
Municipal separate storm sewer systems (MS4s) discharges
Part 122
Part 125
Part 133
Part 122
Part 403
Parts 405-471
Part 122
Part 257
Part 501
Part 503
Part 122
Part 125
Part 122
Part 122
Part 125
Non-
municipal
(Industrial)
Process wastewater discharges
Part 122
Part 125
Parts 405-471
Non-process wastewater discharges
Part 122
Part 125
Stormwater discharges associated with industrial activity
Part 122
Part 125
Stormwater discharges from construction activities*
Part 122
Part 125
Cooling water intake structures (CWIS)
Part 122
Part 125
Part 401
Concentrated animal feeding operations (CAFOs)
Part 122
Part 123
Part 125
Part 412
Concentrated aquatic animal production (CAAP) facilities
Part 122
Part 125
Part 451
Vessel Discharges
Part 122
* Though Stormwater discharges from construction activity resulting in disturbance of 5 or more acres of total land area technically
are considered, "Stormwater discharges associated with industrial activity" as defined by §122.26(b)(14)(x), these discharges are
commonly referred to as Stormwater discharges from large construction activities.
POTWs receive, primarily, domestic sewage from residential and commercial customers. Larger POTWs
also typically receive and treat wastewater from industrial facilities (indirect dischargers) connected to the
collection system. The types of pollutants treated by a POTW always include conventional pollutants and
may include nonconventional and toxic pollutants, depending on the characteristics of the sources
discharging to the POTW. The treatment provided by a POTW typically produces a treated effluent and a
biosolids (sewage sludge) residual.
2.3.1.2 The
The National Pretreatment Program regulates the introduction of
nondomestic (i.e., industrial and commercial) wastewater to POTWs. Because such discharges are treated
by the POTW before release to a water of the United States, they are termed indirect discharges. The
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pretreatment program prohibits industrial and commercial indirect dischargers from discharging
pollutants to a POTW that will pass through the POTW to receiving waters or interfering with POTW
treatment processes or contaminating sewage sludge. The federal program also requires certain indirect
dischargers to meet technology-based requirements developed specifically for such POTW users that are
similar to those for direct dischargers.
EPA's pretreatment regulations require certain POTWs to develop a pretreatment program, the
requirements of which are generally included as conditions of a POTW's NPDES permit. The federal
regulations specifying which POTWs must have pretreatment programs, and the authorities and
procedures that must be developed by the POTW before program approval, are in Part 403. The
requirement to develop and implement a local pretreatment program typically is included as a special
condition in the POTW's NPDES permit. Section 9.2.1 of this manual includes a discussion on
incorporating pretreatment special conditions into permits.
2.3.1.3 Biosolids (Sewage Sludge)
In 1987 Congress amended CWA section 405 to establish a comprehensive sewage sludge program
. The program regulates the use and disposal of sewage
sludge by POTWs and by other TWTDS. TWTDS include facilities that generate sewage sludge, provide
commercial treatment of sewage sludge, manufacture a product derived from sewage sludge, or provide
disposal of sewage sludge. CWA section 405 required EPA to develop technical standards that establish
sewage sludge management practices and acceptable levels of toxic pollutants in sewage sludge. The
terms biosolids, sewage sludge, and municipal sludge are used interchangeably throughout this document.
Regulations for state sewage sludge program approval are at Part 123 or Part 501 (depending on whether
the state wishes to administer the sewage sludge program under its NPDES program or under another
program, e.g., a solid waste program). The technical standards governing sewage sludge use and disposal
are in Part 503. TWTDS not otherwise subject to the NPDES permit requirements under CWA section
402 must apply for and receive a permit addressing standards for use and disposal of sewage sludge in
Part 503. Details of this rule are described in A Plain English Guide to the EPA Part 503 Biosolids Rule2
. Where applicable, sewage sludge management requirements may be
included as a special condition in permits issued to POTWs. Section 9.2.2 of this manual includes a
discussion on incorporating special conditions that address sewage sludge requirements.
2.3.1.4 Combined Sewer Overflows (CSOs)
An additional concern for some older POTWs may be combined sewer systems (CSS), which are
wastewater collection systems owned by a state or municipality [as defined by CWA section 502(4)] that
convey sanitary wastewater (domestic, commercial and industrial wastewaters) and stormwater through a
single-pipe system to a POTW [as defined by § 403.3(q)]. EPA estimates that CSSs serve about 40
million people in 772 communities nationwide . During dry weather, CSSs
collect and convey domestic, commercial, and industrial wastewater to a POTW; however, during periods
of rainfall, snowmelt, and other forms of precipitation, the systems can become overloaded. When that
overloading occurs, the CSS can overflow at designed relief points and discharge a combination of
untreated sanitary wastewater and stormwater directly to a surface waterbody.
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A combined sewer overflow (CSO) is the discharge from a CSS at a point before
the POTW. CSOs can be a major source of water pollution in communities served by CSSs. CSOs often
contain high levels of suspended solids (SS), pathogenic microorganisms, toxic pollutants, floatables,
nutrients, oxygen-demanding organic compounds, oil and grease, and other pollutants, causing water
quality standards to be exceeded.
To address CSOs, EPA issued the National CSO Control Strategy (54 FR 37370, September 8, 1989).
While implementation of the 1989 strategy has resulted in progress toward controlling CSOs, significant
public health and water quality risks remain. To expedite compliance with the CWA, and to elaborate on
the 1989 strategy, EPA, after collaboration with other CSO stakeholders (communities with CSSs, state
water quality authorities, and environmental groups), published the CSO Control Policy
(59 FR 18688, April 19, 1994). The 1994 CSO policy represents a
comprehensive national strategy to ensure that municipalities, permitting authorities, water quality
standards authorities, and the public engage in a comprehensive and coordinated planning effort to
achieve cost-effective CSO controls that ultimately meet appropriate health and environmental objectives.
The Wet Weather Water Quality Act of 2000 stipulates that NDPES permits, enforcement orders, or
decrees must conform to the 1994 CSO Policy [CWA section 402(q)].
Before issuing a permit with conditions that address CSOs, permit writers should consult the CSO
Control Policy and associated guidance. Section 9.2.3 of this manual includes a discussion on
incorporating appropriate CSO permit conditions.
2.3.1.5 Sanitary Sewer Overflows (SSOs)
Properly designed, operated, and maintained sanitary sewer systems are meant to collect and transport all
the sewage that flows into them to a POTW; however, occasional, unintentional spills of raw sewage from
municipal sanitary sewers occur in almost every system. Such types of releases are called sanitary sewer
overflows (SSOs) .
SSOs have a variety of causes including severe weather, improper system operation and maintenance, and
vandalism. EPA estimates that over 40.000 SSO events occur per year in the United States (excluding
basement backups). Overflows of untreated wastewater can present risks of human exposure when
released to certain areas, such as streets, private property, basements, and receiving waters used for
drinking water, fishing and shellfishing, or contact recreation. A description of the extent of human health
and environmental impacts caused by releases of untreated sewage, along with other information, is
provided in the Report to Congress on the Impacts and Control of CSOs and SSOs3
. That 2004 report shows that NPDES permit requirements establishing
clear reporting, record keeping, third party notification of overflows from municipal sewage collection
systems, and clear requirements to properly operate and maintain the collection system, are critical to
effective program implementation.
EPA has developed a draft fact sheet and draft
model permit conditions that explain how NPDES
permitting authorities can better address SSOs and sanitary sewer collection systems. Section 9.2.4 of this
manual discusses incorporation of conditions to address SSOs in NPDES permits.
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2.3.1.6 Municipal Separate Storm Sewer Systems (MS4s)
Stormwater from major metropolitan areas is a significant source of pollutants discharged to waters of the
United States. While rainfall and snow are natural events, the nature of storm water discharges and their
impact on receiving waters are greatly affected by human activities and land use. Stormwater from lands
modified by human activities, such as metropolitan areas and urban streets, can affect surface water
resources by modifying natural flow patterns or by elevating pollution concentrations and loadings.
To address such concerns, the 1987 amendments to the CWA added section 402(p), a provision that
directed EPA to establish phased NPDES requirements for Stormwater discharges. Phase I of the
Stormwater program addresses permits for discharges from medium and large MS4s serving a population
of 100,000 or more, as well as certain categories of industrial activity, including construction activity
disturbing greater than 5 acres. Phase II expanded the Stormwater program to include small MS4s and
construction activity disturbing between 1-5 acres.
The MS4 Stormwater application regulations (Phase I) established requirements for a two-part permit
application that allowed large and medium local governments to help define priority pollutant sources in
the municipality and to develop and implement appropriate controls for such discharges to MS4s (55 FR
47990, November 16, 1990). Part II of the application requires municipal applicants to propose municipal
Stormwater management programs to control pollutants to the maximum extent practicable (MEP) and to
effectively prohibit non-stormwater discharges to the municipal system. Medium and large MS4 operators
are required to submit comprehensive permit applications and are issued individual permits.
Phase II of the Stormwater program extended the NPDES permitting program to small MS4s in urbanized
areas (64 FR 68722, December 8, 1999). The Phase IIMS4 regulations require small MS4s to develop a
program to address six minimum control measures that include BMPs and measurable goals for each
BMP. Permit writers have the option of permitting regulated small MS4 operators using an individual
permit, a general permit, or a modification of an existing Phase I MS4's individual permit (although the
vast majority of small MS4s have been covered under general permits).
Municipal Stormwater management programs combine source controls and management practices that
address targeted sources in the boundaries of the municipal system. For example, a municipality that
expects significant new development may focus more on proposing requirements for new development
and construction. On the other hand, a municipality that does not expect significant new development
could focus more on municipal activities that affect Stormwater quality such as: maintenance of leaking
sanitary sewers, road de-icing and maintenance, operation of municipal landfills, flood control efforts,
and control of industrial contributions of Stormwater.
MEP is not precisely defined so as to allow maximum flexibility in MS4 permitting to optimize
reductions in Stormwater pollutants on a location-by-location basis (64 FR 68754, December 8, 1999).
Therefore, permit writers must rely on application requirements specified in the regulations and the
applicant's proposed management program when developing appropriate permit conditions. The
Stormwater Phase II rule was challenged in the courts, with the U.S. Court of Appeals for the Ninth
Circuit generally upholding the Phase II rule but remanding three issues back to EPA. EPA issued
guidance on April 16, 2004 for how new general permits should address the remanded issues of public
availability of notices of intent (NOIs), opportunity for public hearings, and permitting authority reviews
of NOIs titled Implementing the Partial Remand of the Stormwater Phase II Regulations Regarding
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Notices of Intent & NPDES General Permitting for Phase IIMS4s4
.
In addition to information on the Stormwater Discharges From Municipal Separate Storm Sewer Systems
(MS4s) Website . EPA has developed the following guidance
documents and memoranda to help permit writers and permittees implement the municipal Stormwater
program:
Guidance Manual for the Preparation of Part 2 of the NPDES Permit Applications for Discharge
from Municipal Separate Storm Sewer Systems5 .
Interim Permitting Approach for Water Quality-Based Effluent Limitations in Stormwater
Permits .
Establishing Total Maximum Daily Load (TMDL) Waste load Allocations (WLAs)for Storm
Water Sources and NPDES Permit Requirements Based on Those WLAs1
.
MS4 Program Evaluation Guidance* .
MS4 Permit Improvement Guide9 .
The application requirements for Stormwater discharges from MS4s serving a population greater than
100,000 and for Stormwater discharges from small MS4s are discussed in sections 4.3.10 and 4.3.11 of
this manual.
2.3.2 NPDES Program Areas Applicable to Non-Municipal Sources
Non-municipal sources include industrial and commercial facilities, industrial Stormwater (including large
construction activities), and discharges from small construction activity, concentrated animal feeding
operations (CAFOs) and concentrated aquatic animal production (CAAP) facilities. Unlike municipal
sources, the types of raw materials, production processes, treatment technologies used and pollutants
discharged at industrial facilities vary widely and are dependent on the type of industry and specific
facility characteristics. The operations, however, generally are carried out within a more clearly defined
area; thus, the collection systems are less complex than POTW collection systems. In addition, unlike
biosolids at POTWs, the NPDES program does not regulate residuals (sludge) generated by non-
municipal facilities.
Non-municipal facilities can have discharges of Stormwater that might be contaminated through contact
with manufacturing activities or raw material and product storage, or they can have non-process
wastewater discharges such as non-contact cooling water. In addition, some non-municipal facilities take
in cooling water. Those discharges and intakes may be regulated under an NPDES permit in addition to
any process wastewater.
2.3.2.1 Process Wastewater
Industrial and commercial facilities often use water in the manufacture and processing of products. The
regulations at § 122.2 define process wastewater as, "[a]ny water which, during manufacturing or
processing, comes into direct contact with, or results from the production or use of any raw material,
intermediate product, finished product, byproduct, or waste product."
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Process wastewater can contain pollutants at levels that could affect the quality of receiving waters. The
NPDES permit program establishes specific requirements for discharges of process wastewater from
industrial and commercial sources. If a facility discharges directly to surface water, it would require an
individual or general NPDES permit. An industrial or commercial facility also may discharge wastewater
to a municipal sewer system, which would be covered under the NPDES pretreatment program. Many
types of industrial facilities, whether they discharge directly to surface water or to a municipal sewer
system, are covered by effluent guidelines and standards (see section 5.2 of this manual). The stormwater
that runs off the property of an industrial or commercial facility or from a construction site might require
an NPDES permit under the industrial stormwater program (see section 2.3.2.3 below).
2.3.2.2 Non-Process Wastewater
Industrial and commercial facilities often use water for purposes other than processing products, such as
using non-contact cooling water for heat exchange, and may discharge wastewater from sources such as
sanitary or cafeteria wastes. Like process wastewater, non-process wastewater is regulated under the
NPDES program. Non-process wastewater might also be important to the permit writer when drafting
monitoring conditions for facilities where the non-process wastewater dilutes the concentration of
pollutants of concern in process wastewater. The permit writer must ensure that specified monitoring
locations ensure accurate measurement for compliance with all effluent limitations.
2.3.2.3 Stormwater Associated with Industrial Activity
To minimize the impact of stormwater discharges from industrial facilities, the NPDES program includes
an industrial stormwater permitting component. Operators of industrial facilities included in 1 of the 11
categories of stormwater discharges associated with industrial activity that discharge or propose to
discharge stormwater to an MS4 or directly to waters of the United States require authorization under an
NPDES industrial stormwater permit. EPA published permit regulations and permit application
requirements for stormwater discharges associated with industrial activity in 55 FR 48063, November 16,
1990.
Permit Regulations for Stormwater Associated with Industrial Activity
The regulations define stormwater discharges associated with industrial activity as discharges from any
conveyance used for collecting and conveying stormwater and that is directly related to manufacturing,
processing, or raw materials storage areas at an industrial plant. The regulations at § 122.26(b)(14)(i - xi)
identify the following 11 industrial categories required to apply for NPDES permits for stormwater
discharges:
Facilities subject to stormwater effluent guidelines, new source performance standards, or toxic
pollutant effluent standards under Parts 400-471 (Subchapter N).
Certain heavy manufacturing facilities (lumber, paper, chemicals, petroleum refining, leather
tanning, stone, clay, glass, concrete, ship construction).
Active and inactive mining operations and oil and gas operations with contaminated stormwater.
Hazardous waste treatment, storage, or disposal facilities, including Resource Conservation and
Recovery Act (RCRA) Subtitle C facilities.
Landfills, land application sites, open dumps, and RCRA Subtitle D facilities.
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Recycling facilities, including metal scrap yards, battery reclaimers, salvage yards, and
automotive junkyards.
Steam electric power generating facilities, including coal-handling sites.
Transportation facilities that have vehicle maintenance shops, equipment cleaning operations, or
airport deicing operations.
Major POTW sludge handling facilities, including on-site application of sewage sludge.
Construction activities that disturb five acres or more (see subsection below).
Light industrial manufacturing facilities.
Operators of industrial facilities that are federally, state- or municipally owned or operated that meet the
above descriptions must also submit applications.
EPA issued a final rule for Phase II of the stormwater program in 64 FR 68722, December 8, 1999. That
rule clarified that stormwater discharges from industrial facilities that have no exposure of industrial
activities or materials to stormwater may be conditionally excluded from the stormwater permitting
program. To qualify for the no exposure exclusion, the industrial operator must complete a no exposure
certification form and submit this to EPA once every 5 years. For more information, see the Conditional
No Exposure Exclusion Website .
Generally, EPA- or state-issued general permits regulate stormwater discharges from industrial,
construction and Phase II municipal sources, while Phase I municipal sources usually are issued
individual permits. In some cases, stormwater conditions may be incorporated into a comprehensive
individual NPDES permit for a facility or a stormwater-specific individual NPDES permit. Incorporating
permit conditions to address stormwater discharges associated with industrial and construction activities
into an individual facility permit is discussed in the subsections below. For more information regarding
the scope of the NPDES stormwater program, see the NPDES Stormwater Program Website
.
Permit Conditions for Stormwater Discharges Associated with Industrial Activity
All stormwater discharges associated with industrial activity that discharge stormwater through a separate
MS4 or discharge directly to waters of the United States are required to obtain an NPDES permit.
Because of the large number of facilities requiring permits, EPA and most NPDES-authorized states
choose to issue general permits to regulate stormwater discharges. The Phase I rule in 1990 established
the concept of a permitting exemption for industrial facilities with little or no likelihood of discharging
contaminated stormwater; however, this exemption was not well-defined or required to be submitted to
the NPDES permitting authority. The Phase II rule in December 1999 clarified and expanded the no
exposure certification requirement to require industrial facilities with no exposure of industrial processes
to stormwater to submit a written certification notifying EPA or the authorized state that the facility
wishes to be excluded from the NPDES program.
Each industrial facility covered under an EPA-issued stormwater general permit must meet the numeric
and non-numeric effluent limitations established in the general permit. Industrial facilities can meet those
effluent limitations by implementing control measures, including BMPs, that control the discharge of
stormwater associated with industrial activity.
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The EPA- and state-issued stormwater general permits generally require the facility to develop and
implement a site-specific stormwater pollution prevention plan (SWPPP). The SWPPP describes the
control measures, whether structural or nonstructural, which are used for controlling stormwater
discharges from the industrial facility. The special conditions component of EPA's stormwater general
permits identifies the requirements that must be documented in the SWPPP, including the following:
A description of potential pollutant sources at the facility, including the following:
- A map of the facility indicating the drainage areas of the site and the industrial activities that
occur in each drainage area.
- An inventory of materials that could be exposed to stormwater.
A description of the likely sources of pollutants from the site and a prediction of the
pollutants likely to be present in the stormwater.
The history of spills and leaks of toxic and hazardous materials over the past 3 years.
The measures and controls that will be implemented to prevent or minimize pollution of
stormwater, including the following:
Good housekeeping or upkeep of industrial areas exposed to stormwater.
- Preventive maintenance of stormwater controls and other facility equipment.
Spill prevention and response procedures.
- Testing of outfalls to ensure that there are no illicit discharges.
Employee training on pollution prevention measure and controls, and record keeping.
A permit writer's best sources of information for developing appropriate special conditions for
stormwater control measures are other stormwater general permits. Using existing general permits as the
basis for special conditions is encouraged because doing so will reduce duplication of effort. A listing of
individual and general permits (stormwater and non-stormwater) issued by EPA and authorized states is
on the View NPDES Individual and General Permits Website . In addition
to the Stormwater Discharge From Industrial Facilities Website . EPA
published Developing Your Stormwater Pollution Prevention Plan: A Guide for Industrial Operators10
to help permit writers identify components of SWPPPs
and BMPs and to help permittees develop their own plans. Section 4.3.8 of this manual discusses Form
2F and individual permit requirements for stormwater discharges associated with industrial activity.
Permit Conditions for Stormwater Discharges associated with Construction Activities
EPA and most NPDES-authorized states have issued NPDES general stormwater permits for discharges
associated with construction activity that are separate from the industrial stormwater general permits. The
Phase I stormwater regulations require permit coverage for all construction activity that results in the
disturbance of five acres or greater of the total land area. This includes disturbance of less than five acres
of total land area that is part of larger common plan of development or sale if the larger common plan will
ultimately disturb five acres of more. The Phase II stormwater regulations require permit coverage for all
construction activity that result in land disturbance of equal to or greater than one acre and less than five
acres. This includes the disturbance of less than one acre of total land area that is part of a larger common
plan of development or sale if the larger common plan will ultimately disturb equal to or greater than one
and less than five acres. Since March 2003, most construction activity disturbing one to five acres has
been required to comply with the conditions of the relevant NPDES permit (typically under the relevant
construction general permit for stormwater discharges), though states have the option of not requiring the
submittal of NOIs for stormwater discharges associated with small construction activity.
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EPA and NPDES-authorized state permitting authorities may include permit conditions that incorporate
qualifying state or local erosion and sediment control program requirements by reference. A qualifying
state or local erosion and sediment control program is one that includes the requirements at § 122.44(s).
Once EPA or an NPDES authorized state identifies and incorporates a qualifying local program in their
NPDES construction general permit, operators can follow the erosion and sediment control requirements
of the qualifying local program. By incorporating the qualifying local program by reference the
permitting authority can avoid duplicative or conflicting erosion and sediment control requirements
between the local program requirements and the NPDES general permit control requirements addressing
stormwater discharges associated with construction activity. Operators that are engaged in construction
activity within a qualifying program must still submit an NOI under the appropriate construction general
permit and comply with all other permit conditions.
The permit requirements in a construction general permit may be similar to those in an industrial general
permit, including the development of a SWPPP. In addition to the Stormwater Discharges from
Construction Activities Website . EPA also developed the
Stormwater Pollution Prevention Plans for Construction Activities Website
. Section 4.3.9 of this manual discusses individual permit requirements for
stormwater discharges associated with construction activity.
2.3.2.4 Cooling Water Intake Structures
CWA section 316(b) provides that any standard established pursuant to CWA sections 301 or 306 and
applicable to a point source will require that the location, design, construction, and capacity of cooling
water intake structures reflect the best technology available for minimizing adverse environmental
impact. This CWA provision is unique because it addresses the intake of water, in contrast to other
provisions that regulate the discharge of pollutants into waters of the United States. EPA has established
national performance standards under CWA section 316(b) designed to reduce the impingement and
entrainment offish and other aquatic organisms as they are drawn into a facility's cooling water intake
structure(s). Impingement occurs when organisms are trapped against cooling water intake structures by
the force of water being drawn through the intake structure. Entrainment occurs when organisms are
drawn through a cooling water intake structure into a cooling system, through the heat exchanger, and
then pumped back out into the waterbody. For more information, see section 4.3.12 of this manual.
In April 1976, EPA published regulations at Part 402 to address cooling water intake structures. Fifty-
eight electric utility companies challenged the final rule. The U.S. Court of Appeals for the Fourth Circuit
remanded the rule in 1977, and in 1979, EPA withdrew Part 402. Beginning in 1977, NPDES permit
authorities made decisions implementing CWA section 316(b) on a case-by-case basis using best
professional judgment (BPJ) (§§ 125.90(b) and 401.14).
In the 1990s, EPA began developing CWA section 316(b) regulations establishing national standards.
EPA divided the rulemaking into three phases:
Phase I addressed new facilities and was completed in December 2001 (Part 125, Subpart I).
Phase II addressed existing electric generating plants that use at least 50 million gallons per day
(mgd) of cooling water was completed in July 2004 (Part 125, Subpart J).
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Phase III addressed other existing facilities, including small existing electric generating plants
that use less than 50 mgd of cooling water, manufacturers, and new offshore and coastal oil and
gas extraction facilities.
The Phase III regulations, finalized in June 2006, establish national standards only for new offshore and
coastal oil and gas extraction facilities (Part 125, Subpart N). EPA decided that other Phase III industrial
facilities withdrawing water for cooling purposes would not be covered by national standards but would
continue to be subject to CWA section 316(b) requirements set by the NPDES Permitting Director on a
case-by-case, BPJ basis (§§ 125.90(b) and 401.14).
All three regulations were subject to judicial challenges. While the Phase I rule was largely upheld, the
court reviewing the Phase II regulation rejected a number of its provisions. Under remands from the
reviewing courts, EPA is reevaluating the Phase II regulation and the decision in the Phase III regulation
not to establish national standards for existing Phase III facilities. In the interim, as noted above, NPDES
permits must include CWA section 316(b) conditions developed on a case-by-case basis. For the most
current information on regulatory requirements, see the Cooling Water Intake Structure Program Website
. and for additional Cooling Water Intake Structures regulatory
requirements, see section 4.3.12 of this manual.
2.3.2.5 Concentrated Animal Feeding Operations (CAFOs)
Animal feeding operations (AFOs) are agricultural facilities where animals are kept and raised in confined
situations. AFOs typically maintain animals, feed, and manure and have production operations in a
limited land area. Manure and wastewater from AFOs have the potential to contribute pollutants such as
nitrogen and phosphorus, organic matter, sediments, pathogens, heavy metals, hormones, antibiotics, and
ammonia to the environment. An AFO is a lot or facility (other than an aquatic animal production facility)
where the following conditions are met:
Animals have been, are, or will be stabled or confined and fed or maintained for a total of 45 days
or more in any 12-month period.
Crops, vegetation, forage growth, or post-harvest residues are not sustained in the normal
growing season over any portion of the lot or facility.
AFOs that meet the regulatory definition of a CAFO, or that are designated as CAFOs by the permitting
authority, and that discharge or propose to discharge are required to be permitted under the NPDES
permitting program.
An animal operation must meet the definition of an AFO [§ 122.23(b)(l)] before it can be considered a
CAFO. To be defined as a CAFO, an AFO must meet the regulatory definition [§§ 122.23(b)(4) or
122.23(b)(6)] of a large or medium CAFO or must be designated by the permitting authority
[§ 122.23(c)]. Only CAFOs that discharge or propose to discharge are subject to NPDES permitting
requirements.
CAFOs are subject to requirements that limit discharges from the production area and requirements
applicable to land application areas under the control of the CAFO operator. Large CAFOs are subject to
a no discharge requirement for production areas, whereas other CAFOs are subject to BPJ requirements
for their production areas. One of the principal substantive pollution control conditions in any CAFO
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permit is the requirement to implement the terms of the nutrient management plan (NMP) incorporated
into the permit when permit authorization is granted. For more information, see the Animal Feeding
Operations Website . In addition, section 4.3.4 of this manual discusses
application requirements for CAFOs.
2.3.2.6 Concentrated Aquatic Animal Production (CAAP) Facilities
CAAP facilities also are regulated under the NPDES program. In 2004 EPA promulgated new effluent
guidelines that address CAAP facilities. The effluent guidelines apply to CAAP facilities (flow-through,
recirculating, and net pen) that directly discharge wastewater and have annual production equal to or
greater than 100,000 pounds of aquatic animals. The rule requires a BMP plan and implementation of
measures, including recordkeeping and reporting requirements, to minimize discharges of solids, to
prevent spills of drugs, feed, and chemicals that could result in discharges to waters of the United States,
and to ensure proper maintenance of the facility. A facility that does not meet the effluent guideline
threshold might still need an NPDES permit if it meets the CAAP facilities thresholds established in the
NPDES regulations at § 122.24(b) or if it is designated as a CAAP facility under the designation authority
in § 122.24(c). For more information, see the Aquatic Animal Production Industry Effluent Guidelines
Website .
2.3.2.7 Vessel Discharges
On March 30, 2005, the U.S. District Court for the Northern District of California (in Northwest
Environmental Advocates et al. v. EPA) ruled that the EPA regulation excluding discharges incidental to
the normal operation of a vessel from NPDES permitting exceeded the Agency's authority under the
CWA. On September 18, 2006, the Court issued an order revoking this regulation [40 CFR 122.3(a)] as of
September 30, 2008. EPA appealed the District Court's decision, and on July 23, 2008, the Ninth Circuit
upheld the decision, leaving the September 30, 2008, vacatur date in effect. In response to the Court
order, EPA developed two proposed permits to regulate discharges from vessels. The district court
ultimately extended the date of vacatur to February 6, 2009.
In July 2008, Congress amended the CWA (P.L. No. 110-288) to add a new section 402(r), which
excludes discharges incidental to the normal operation of a recreational vessel from NPDES permitting.
Instead, it directs EPA to regulate those discharges under a newly created CWA section 312(o). As a
result of the law, EPA did not finalize the previously proposed Recreational Vessel General Permit and is
instead undertaking rulemaking to develop BMPs for these vessels under the authority of CWA section
312(o).
In July 2010 P.L. 111-215 (Senate Bill S. 3372) was signed into law. This law amends P.L. 110-299
(Senate Bill S. 3298), which generally imposes a moratorium during which time neither EPA nor states
may require NPDES permits for discharges incidental to the normal operation of commercial fishing
vessels and other non-recreational vessels less than 79 feet. As a result, of P.L. 110-299, the Vessel
General Permit (VGP) does not cover vessels less than 79 feet, or commercial fishing vessels, unless they
have ballast water discharges. P.L. 111-215 extended the expiration date of the moratorium from July 31,
2010, to December 18, 2013.
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As a result of the court ruling, EPA issued the VGP on December 18, 2008. The 2008 VGP regulates
discharges incidental to the normal operation of vessels operating in a capacity as a means of
transportation. The VGP includes the following:
general effluent limits applicable to all discharges.
general effluent limits applicable to 26 specific discharge streams.
narrative water-quality based effluent limits.
inspection, monitoring, recordkeeping, and reporting requirements.
additional requirements applicable to certain vessel types.
EPA estimates that approximately 61,000 domestically flagged commercial vessels and approximately
8,000 foreign flagged vessels could be affected by this permit.
Because this area of the NPDES permit program is relatively new and continues to evolve, for the most
current information, see EPA's Vessel Discharges Website .
2.4 Major/Minor Facility Designation
In addition to categorizing facilities as municipal and non-municipal, EPA has also developed criteria to
determine which of the sources should be considered major facilities. The distinction was made initially
to assist EPA and states in setting priorities for permit issuance and reissuance. The regulations at § 122.2
define major facility as, "any NPDES facility or activity classified as such by the Regional Administrator,
or in the case of approved state programs, the Regional Administrator in conjunction with the [s]tate
Director." All facilities that are not designated as majors are considered minor facilities.
Through policy, including the memoranda Procedures for Revising the Major Permit List11
and Delegation of Updates to Major/Minor Lists12
. EPA has established working definitions for POTW and non-
municipal major facilities. For POTWs, major facilities are those that have a design flow of one million
gallons per day or greater or serve a population of 10,000 or more or cause significant water quality
impacts. Non-POTW discharges are classified as major facilities on the basis of the number of points
accumulated using the NPDES Permit Rating Work Sheet . The
worksheet evaluates the significance of a facility using several criteria, including toxic pollutant potential,
flow volume, and water quality factors such as impairment of the receiving water or proximity of the
discharge to coastal waters.
2.5 Growth and Change in the NPDES Program
The basic structure of the NPDES program has remained the same since the 1972 Federal Water Pollution
Control Act amendments, but as EPA develops new regulations, policies, and guidance or modifies
existing program requirements and guidance, the existing program is refined and new aspects of the
program can emerge. To stay informed about the most recent program developments, permit writers
should visit EPA's NPDES Program Website frequently.
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1 Prothro, M. 1983. EPA's Authority to Issue NPDES General Permits in Approved NPDES States. U.S. Environmental
Protection Agency, Office of Water. Memorandum, July 11, 1983. .
2 U.S. Environmental Protection Agency. 1994. A Plain English Guide to the EPA Part 503 Biosolids Rule. EPA/832/R-93/003.
U.S. Environmental Protection Agency, Office of Wastewater Management, Washington, DC.
.
4 Hanlon, JA. 2004. Implementing the Partial Remand of the Stormwater Phase II Regulations Regarding Notices of Intent &
NPDES General Permitting for Phase IIMS4s. U.S. Environmental Protection Agency, Office of Wastewater Management.
Memorandum, April 16,2004. .
U.S. Environmental Protection Agency. 1992. Guidance Manual for the Preparation of Part 2 of the NPDES Permit
Application for Discharges from Municipal Separate Storm Sewer Systems. EPA-833/B-92-002. U.S. Environmental Protection
Agency, Office of Water, Washington, DC. .
6 Perciasepe, R. 1996. Interim Permitting Approach for Water Quality-Based Effluent Limitations in Stormwater Permits. U.S.
Environmental Protection Agency, Office of Water. Memorandum, September 1, 1996. .
7 Wayland, R.H., III, and J.A. Hanlon. 2002. Establishing Total Maximum Daily Load (TMDL) Waste load Allocations (WLAs)
forStorm Water Sources and NPDES Permit Requirements Based on Those WLAs. U.S. Environmental Protection Agency,
Office of Wetlands, Oceans and Watersheds and Office of Wastewater Management. Memorandum, November 22, 2002.
.
8 U.S. Environmental Protection Agency. 2007. MS4 Program Evaluation Guidance. EPA-833-R-07-003. U.S. Environmental
Protection Agency, Office of Wastewater Management. Washington, DC.
.
9 U.S. Environmental Protection Agency. 20W.MS4 Permit Improvement Guide. EPA833-R-10-001. U.S. Environmental
Protection Agency. Office of Water, Washington, DC.
10 U.S. Environmental Protection Agency. 2009. Developing Your Stornnvater Pollution Prevention Plan: A Guide for Industrial
Operators. EPA 833-B-09-002. U.S. Environmental Protection Agency, Office of Water, Washington, DC.
.
11 Dougherty, Cynthia. 1988. Procedures for Revising the Major Permit List. U.S. Environmental Protection Agency, Permits
Division. Memorandum, December 28, 1988. .
12 Pendergast, James F. 1995. Delegation of Updates to Major/Minor Lists. U.S. Environmental Protection Agency, Office of
Wastewater Management. Memorandum, February 6, 1995. .
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CHAPTER 3. Overview of the NPDES Permitting Process
This chapter presents an overview of the different types of National Pollutant Discharge Elimination
System (NPDES) permits, the major permit components, and the permit development and issuance
process. The permit process is illustrated by flow charts. The tasks identified within the flow charts are
described in detail in subsequent chapters.
3.1 Types of Permits
The two basic types of NPDES permits are individual and general permits. These permit types share the
same components but are used under different circumstances and involve different permit issuance
processes.
3.1.1 Individual Permits
An individual permit is a permit specifically tailored to an individual facility. Upon receiving the
appropriate application form(s), the permitting authority develops a permit for that facility on the basis of
information from the permit application and other sources (e.g., previous permit requirements, discharge
monitoring reports, technology and water quality standards, total maximum daily loads, ambient water
quality data, special studies). The permitting authority then issues the permit to the facility for a specific
period not to exceed 5 years, with a requirement to reapply before the expiration date.
3.1.2 General Permits
A permitting authority develops and issues a general permit to cover multiple facilities in a specific
category of discharges or of sludge use or disposal practices. General permits can be a cost-effective
option for agencies because of the large number of facilities that can be covered under a single permit.
According to Title 40 of the Code of Federal Regulations (CFR) 122.28(a)(2), general permits may be
written to cover stormwater point sources or other categories of point sources having the following
common elements:
Sources that involve the same or substantially similar types of operations.
Sources that discharge the same types of wastes or engage in the same types of sludge use or
disposal.
Sources that require the same effluent limitations or operating conditions, or standards for sewage
sludge use or disposal.
Sources that require the same monitoring where tiered conditions may be used for minor
differences within a class (e.g., size or seasonal activity).
Sources that are more appropriately regulated by a general permit.
The regulations at § 122.28(a)(l) provide for general permits to cover dischargers within an area
corresponding to specific geographic or political boundaries such as the following:
Designated planning area.
Sewer district.
City, county, or state boundary.
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State highway system.
Standard metropolitan statistical area.
Urbanized area.
The regulation also allows a general permit to cover any other appropriate division or combination of
such boundaries. For example, EPA has issued general permits that cover multiple states, territories, and
tribes where EPA is the permitting authority.
Where a large number of similar facilities require permits, a general permit allows the permitting
authority to allocate resources in a more efficient manner and to provide more timely permit coverage
than issuing an individual permit to each facility. In addition, using a general permit ensures consistent
permit conditions for comparable facilities.
3.2 Major Components of a Permit
All NPDES permits consist, at a minimum, of five sections:
Cover Page: Contains the name and location of the permittee, a statement authorizing the
discharge, and a listing of the specific locations for which a discharge is authorized.
Effluent Limitations: The primary mechanism for controlling discharges of pollutants to
receiving waters. A permit writer spends the majority of his or her time, when drafting a permit,
deriving appropriate effluent limitations on the basis of applicable technology and water quality
standards.
Monitoring and Reporting Requirements: Used to characterize wastestreams and receiving
waters, evaluate wastewater treatment efficiency, and determine compliance with permit
conditions.
Special Conditions: Conditions developed to supplement numeric effluent limitations. Examples
include additional monitoring activities, special studies, best management practices (BMPs), and
compliance schedules.
Standard Conditions: Pre-established conditions that apply to all NPDES permits and delineate
the legal, administrative, and procedural requirements of the NPDES permit.
In addition to the components of the permit, a fact sheet or statement of basis explaining the rationale for
permit conditions makes up part of the documentation that supports a draft permit. Section 11.2 of this
manual includes additional discussion of permit documentation and the required elements of a fact sheet
or statement of basis.
Although the major sections of a permit listed above are part of all permits, the contents of some sections
vary depending on the nature of the discharge (e.g., municipal effluent, industrial process wastewater,
stormwater, vessel discharges) and whether the permit is issued to an individual facility or to multiple
dischargers (i.e., a general permit). Exhibit 3-1 shows the components of a permit and highlights some
distinctions between the contents of NPDES permits for municipal (i.e., POTW) and industrial facilities.
Permit writers should note that it is common for different permitting authorities to use different names for
each section of a permit.
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Mu nicipal/POTW-specif ic
components
Secondary treatment
Equivalent to secondary
Pretreatment
Biosolids
Combined sewer overflows
Sanitary sewer overflows
Exhibit 3-1 Permit components
Components of
all permits
Cover Page
Effluent Limitations
Technology-based
Water quality-based
Monitoring and Reporting
Requirements
Special Conditions
Additional monitoring and special
studies
Best management practices and
pollution prevention
Compliance schedules
Standard Conditions
Industry-specific
components
Effluent limitations guidelines
Best professional judgment
3.3 Overview of the Development and Issuance Process for NPDES
Individual Permits
While the limitations and conditions in NPDES individual permits are unique to each permittee, the
process used to develop the limitations and conditions and issue each permit generally follows a common
set of steps. Exhibit 3-2 illustrates the major steps to develop and issue NPDES individual permits and
also serves as an index for the subsequent chapters of this manual by identifying which chapter presents
more detailed information on each step.
For individual permits, the permitting process generally begins when a facility operator submits an
application. After receiving the application and making a decision to proceed with the permit, the permit
writer reviews the application for completeness and accuracy. When the permit writer determines that the
application is complete and has any additional information needed to draft the permit, the permit writer
develops the draft permit and the justification for the permit conditions (i.e., the fact sheet or statement of
basis).
The first major step in the permit development process is deriving technology-based effluent limitations
(TBELs). Following that step, the permit writer derives effluent limitations that are protective of state
water quality standards (i.e., water quality-based effluent limitations [WQBELs]) as needed. The permit
writer then compares the TBELs with the WQBELs and, after conducting an anti-backsliding analysis if
necessary, applies the final limitations in the NPDES permit. The permit writer must document the
decision-making process for deriving limitations in the permit fact sheet. It is quite possible that a permit
will have limitations that are technology-based for some parameters and water quality-based for others.
For example, a permit could contain effluent limitations for total suspended solids (TSS) based on
national effluent limitations guidelines and standards (effluent guidelines) (technology-based), limitations
for ammonia based on preventing toxicity to aquatic life (water quality-based), and limitations for 5-day
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biochemical oxygen demand (BOD5) that have different bases, such as an average monthly limitation
based on effluent guidelines and a maximum daily limitation based on water quality standards.
Exhibit 3-2 Major steps to develop and issue NPDES individual permits
Receive application
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 9
Chapter 10
Review application for completeness and
accuracy. Request additional information as
necessary
Using application information and other
data, develop technology-based effluent
limitations (TBELs)
Using application information and other
data, develop water quality-based effluent
limitations (WQBELs)
Apply anti-backsliding requirements and
determine final effluent limitations
I
Develop monitoring and reporting requirements
Develop special conditions
Incorporate standard conditions
Prepare fact sheet and supporting
documentation
Prepare public notice and respond to public
comments
Chapter 11
Complete EPA review or CWA Section 401
certification process
Prepare administrative record
Issue the final permit
Implement permit requirements
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After effluent limitation development, the permit writer develops appropriate monitoring and reporting
requirements and facility-specific special conditions. The permit writer then adds standard conditions,
which are the same for all permits.
The next step is to provide an opportunity for public participation in the permit process and EPA review
of the permit or, in the case of an EPA-issued permit, certification under CWA section 401 by the state
with jurisdiction over the receiving water that the permit will comply with its water quality standards. The
permitting authority issues a public notice announcing the draft permit and inviting interested parties to
submit comments. If there is significant public interest, the permitting authority can hold a public hearing.
Taking into consideration the public comments, the permitting authority then produces a final permit,
with careful attention to documenting the process and decisions for the administrative record, and issues
the final permit to the facility. The permitting authority might decide to make significant changes to the
draft permit according to public comment and then provide another opportunity for public review and
comment on the revised permit. Section 11.3 of this manual discusses items to address before final permit
issuance in more detail.
3.4 Overview of the Development and Issuance Process for NPDES
General Permits
The process for developing and issuing NPDES general permits is similar to the process for individual
permits; however, there are some differences in the sequence of events. Exhibit 3-3 illustrates the major
steps to develop and issue NPDES general permits.
Exhibit 3-3 Major steps to develop and issue NPDES general permits
Identify need and collect data
T
Develop permit and fact sheet
Effluent limitations
Monitoring requirements
Special conditions
Standard conditions
T
Issue public notice and receive public comments
T
Complete EPA review or CWA Section 401
certification process
T
Prepare administrative record
T
Issue final permit
T
Receive notice of intent from facilities to be covered
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For general permits, the permitting authority first identifies the need for a general permit and collects data
that demonstrate that a group or category of dischargers has similarities that warrant a general permit. In
deciding whether to develop a general permit, permitting authorities consider whether
A large number of facilities will be covered.
The facilities have similar production processes or activities.
The facilities generate similar pollutants.
Whether uniform WQBELs (where necessary) will appropriately implement water quality
standards.
The remaining steps of the permit process are the same as for individual permits. The permitting authority
develops a draft permit that includes effluent limitations, monitoring conditions, special conditions, and
standard conditions. The permitting authority then issues a public notice and addresses public comments,
completes the EPA review or CWA section 401 certification process, develops the administrative record,
and issues the final permit. The final permit will also establish the requirements for the specific
information that must be submitted by a facility that wishes to be covered under the general permit.
After the final general permit has been issued, facilities that wish to be covered under the general permit
typically submit a Notice of Intent (NOI) to the permitting authority. After receiving the NOI, the
permitting authority can request additional information describing the facility, notify the facility that it is
covered by the general permit, or require the facility to apply for an individual permit.
The following chapters in this manual describe steps in the permitting process in detail. In general, the
chapters focus on the steps necessary to develop and issue an individual permit, but much of the technical
discussion applies equally to general permit development.
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CHAPTER 4. NPDES Permit Application Process
This chapter describes the National Pollutant Discharge Elimination System (NPDES) permit application
process, including the permit writer's role in reviewing the application and evaluating background
information about the applicant. Through this process the permit writer gains an understanding of the
circumstances of the discharge and the characteristics of the proposed effluent, which is necessary to
develop appropriate permit limitations and conditions.
4.1 Who Applies for an NPDES Permit?
The NPDES regulations at Title 40 of the Code of Federal Regulations (CFR) 122.21(a) require that any
person, except persons covered by general permits under § 122.28, who discharges pollutants or proposes
to discharge pollutants to waters of the United States must apply for a permit. Further, § 122.21(e)
prohibits the permitting authority from issuing an individual permit until and unless a prospective
discharger provided a complete application. This regulation is broadly inclusive and ties back to the Clean
Water Act (CWA) section 301 (a) provision that, except as in compliance with the act, ".. .the discharge of
any pollutant by any person shall be unlawful."
In most instances, the permit applicant will be the owner (e.g., corporate officer) of the facility. However,
the regulations at § 122.21(b) require that when a facility or activity is owned by one person but is
operated by another person, it is the operator's duty to obtain a permit. The regulations also require the
application to be signed and certified by a high-ranking official of the business or activity. The signatory
and certification requirements are at § 122.22.
Permits (and applications) are required for most discharges or proposed discharges to waters of the United
States; however, NPDES permits are not required for some activities as specified under the Exclusions
provision in § 122.3. Exceptions include the following:
Discharge of dredged or fill materials into waters of the United States which are regulated under
CWA section 404.
The introduction of sewage, industrial wastes or other pollutants into publicly owned treatment
works (POTWs) by indirect dischargers.
Any discharge in compliance with the instructions of an On-Scene Coordinator pursuant to Part
300 (The National Oil and Hazardous Substances Pollution Contingency Plan) or 33 CFR
153.10(e) (Pollution by Oil and Hazardous Substances).
Any introduction of pollutants from nonpoint source agricultural and silvicultural activities,
including stormwater runoff from orchards, cultivated crops, pastures, range lands, and forest
lands, but not discharges from concentrated animal feeding operations as defined in § 122.23,
discharges from concentrated aquatic animal production facilities as defined in § 122.24,
discharges to aquaculture projects as defined in § 122.25, and discharges from silvicultural point
sources as defined in § 122.27.
Return flows from irrigated agriculture.
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Discharges into a privately owned treatment works, except as the Director may otherwise require
under § 122.44(m).
While those types of discharges have been excluded from permitting requirements under the NPDES
program, they might be subject to controls under other federal or state regulatory programs.
As of the date of this manual's publication, the exclusion for certain discharges incidental to the normal
operation of a vessel is still in the CFR. Similarly, discharges from the application of pesticides consistent
with all relevant requirements under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA)
(i.e., those relevant to protecting water quality) are excluded from NPDES permit coverage in the
following two circumstances: (1) the application of pesticides directly to waters of the United States to
control pests, and (2) the application of pesticides to control pests that are present over waters of the
United States, including near such waters, where a portion of the pesticides will unavoidably be deposited
to waters of the United States to target the pests effectively. However, because of court decisions, the
exclusions for vessels and pesticides are vacated as of February 6, 2009, and April 9, 2011, respectively.
The effect of the vacaturs on the exclusions in § 122.3 is presented in Exhibit 4-1.
Exclusion
Exhibit 4-1 Effect of court decisions on § 122.3
Issue
Vessel Discharges
(www.epa. gov/npdes/vessels)
The Court's ruling does not affect vessel discharge exemptions from
permitting that are specifically provided for in the CWA itself. For example,
§ 502(6)(A) excludes from the act's definition of pollutant sewage from vessels
(including graywater in the case of commercial vessels operating on the Great
Lakes) and discharges incidental to the normal operation of a vessel of the
Armed Forces within the meaning of CWA section 312. As another example,
the CWA section 502(12)(B) provides that discharges from vessels (i.e.,
discharges other than those when the vessel is operating in a capacity other
than as a means of transportation) do not constitute the, "discharge of a
pollutant" when such discharges occur beyond the limit of the 3-mile territorial
sea. Because both a pollutant and a discharge of a pollutant are prerequisites
to the requirement to obtain an NPDES permit, those two statutory provisions
have the effect of exempting the vessel discharges they address from the
requirement to obtain an NPDES permit. In addition, in July 2008, Congress
amended the CWA to add a new section 402(r) to the act, which excludes
discharges incidental to the normal operation of a recreational vessel from
NPDES permitting. For more information, see section 2.3.2.7 of this manual.
Pesticides
(www.epa.gov/npdes/aquaticpesticides)
On January 7, 2009, the 6th Circuit Court vacated the final rule in The
National Cotton Council of America et al. v. United States Environmental
Protection Agency. The court held that while an NPDES permit is not required
for chemical pesticide applications that leave no residuals, an NPDES permit
is required for discharges (1) from chemical pesticide applications to or over,
including near water, where there is a residual, or excess pesticide, in the
water following the application, and (2) from all biological pesticide
applications regardless of whether a residual is left. On June 8, 2009, the
court granted a request from the U.S. Department of Justice for a 2-year stay
of its decision, until April 9, 2011, to provide time for EPA and the states to
develop and issue NPDES general permits for the discharge of pollutants from
the application of pesticides. Before April 9, 2011, permits are not required for
discharges from these applications when applied in accordance with the
product's FIFRA label. Certain related activities continue to be exempt from
permitting under the CWA (i.e., irrigation return flow and agricultural
stormwater runoff).
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4.2 Application Deadlines
The regulations at § 122.21(c) and (d) specify the time to apply for NPDES permits. Exhibit 4-2
summarizes the application deadline requirements for dischargers to be covered by an NPDES permit.
Type of permit
Exhibit 4-2 When to apply for an NPDES permit
Type of discharge Schedule*
Individual
New
Existing
Construction Stormwater
At least 180 days before the date on which the discharge
is to commence
At least 180 days before expiration date of existing permit
At least 90 days before the date on which construction is
to commence
New
Specified in general permit
General
Existing
' Authorized states may use more stringent deadlines.
X number of days following issuance of permit
(specified in the general permit)
Anyone proposing a new discharge must apply to the permitting authority no later than 180 days before
the expected commencement of the discharge if applying for an individual permit. Any person with an
currently effective individual permit must submit an application to the permitting authority at least
180 days before the expiration of its existing individual permit unless permission for a later date has been
granted in accordance with § 122.21(d). For general permits, the deadline for new dischargers to apply is
specified in the general permit. A general permit also may specify a number of days after the general
permit's issuance that operators of existing facilities are given to apply for coverage. Authorized states
may have different schedules for permit applications, but their schedules may be no less stringent than the
federal deadlines. The State Director or the Regional Administrator may allow an individual application
to be submitted at dates later than those specified in the regulations, but not later than the expiration date
of the existing permit.
Note that, according to § 122.6, the conditions of an expired NPDES permit remain in effect until the new
permit is issued, as long as the discharger submitted a complete application in accordance with the
timeframes prescribed in the regulations (or in accordance with state law, in the case of state-administered
NPDES programs). If state law does not allow expired permits to remain in effect until a permit is
reissued, or if the permit application is not on time and complete, the facility may be considered to be
discharging without a permit from the time the permit expired until the effective date of the new permit.
4.3 Application Forms and Requirements for Individual Permits
When a facility needs an individual NPDES permit, it must submit a permit application. Application
forms and requirements are specific to the type of facility and discharge. NPDES permit application
requirements are in Part 122, Subpart B and identified on forms developed by the U.S. Environmental
Protection Agency (EPA). Authorized states are not required to use the EPA application forms; however,
any alternative form used by an authorized state must include the federal requirements at a minimum.
Exhibit 4-3 provides an overview of the types of dischargers required to submit NPDES application
forms, identifies the forms that must be submitted, and references the corresponding NPDES regulatory
citation. In some cases, a facility might need to file more than one application form. For example, an
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existing industrial facility (i.e., renewal) discharging stormwater combined with process and non-process
wastewater might need to submit Form 1, Form 2C, and Form 2F. Section 2.3 of this manual discusses
the NPDES program areas that have application requirements presented below.
Exhibit 4-3 EPA application requirements for NPDES individual permits
Type of facility or program area
Status
Forms
Regulatory citations and
additional application
requirements
(40 CFR)
Municipal facilities
POTWs with design flows greater
than or equal to 0.1 million gallons
per day (mgd)
POTWs with design flows less than
0.1 mgd
TWTDS (sewage sludge)
Concentrated animal production
facilities
Concentrated animal feeding
operations
Concentrated aquatic animal
production facilities
Industrial facilities
Manufacturing facilities
Commercial facilities
Mining activities
Silvicultural activities
Stormwater discharges associated
with industrial activities (except
stormwater discharges associated
with construction activity)
Stormwater discharges associated
with construction activity
Stormwater discharges from MS4s
serving a population greater than
100,000
Stormwater discharges from small
MS4s
Cooling water intake structures
New and existing
New and existing
New and existing
New and existing
Existing
New
(process
wastewater)
New and existing
(non-process
wastewater)
New and existing
New and existing
New and existing
New and existing
New and existing
Form 2A, Parts
A, B and C; Parts
D, E, F, or Gas
applicable
Form 2A, Parts A
and C;
Parts D, E, F, or
G as applicable
Form 2S
Form 1 and
Form 2B
Form 1 and
Form 2C
Form 1 and
Form 2D
Form 1 and
Form 2E
Form 1 and
Form 2F
Form 1
None
None
None
. § 122.21(a)(2)(i)(B)
§122.210)
. § 122.21(a)(2)(i)(B)
§122.210)
. § 122.21(a)(2)(i)(H)
§122.21(q)
. §122.21(a)(2)(i)(A)and(C)
§122.21(f)and(i)
. §122.21(a)(2)(i)(A)and(D)
§122.21(f)and(g)
. §122.21(a)(2)(i)(A)and(E)
§122.21(f)and(k)
§122.21(a)(2)(i)(A)and(F)
§122.21(f)and(h)
§122.21(a)(2)(i)(A)and(G)
§122.21(f)
§ 122.26(c)
. § 122.21(a)(2)(i)(A)
§122.21(f)
§122.26(c)(1)(ii)
§ 122.26(d)
§ 122.33
§122.21(f)
. §122.21(r)
4-4
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4.3.1 Form 1: General Information
All facilities applying for an individual NPDES permit, with the exception of POTWs, treatment works
treating domestic sewage (TWTDS), and municipal separate storm sewer systems (MS4s) applying for a
municipal stormwater permit, must submit Form 1 . The type of general
facility information required by Form 1 is specified in §§ 122.21(a)(2)(i)(A) and 122.21(f) and includes
the following:
Name, mailing address, facility contact, and facility location.
Standard industrial classification (SIC) code and a brief description of the nature of the business.
Topographic map showing the location of the existing or proposed intake and discharge
structures.
4.3.2 Form 2A: New and Existing POTWs
All new and existing POTWs must submit Form 2A . EPA issued a final
rule amending permit application requirements and application forms for POTWs and other TWTDS
(64 FR 42433, August 4, 1999). The rule consolidated POTW application requirements, expanded toxic
monitoring requirements for POTWs, and revised the forms used to submit permit applications. POTWs
must also submit the form for permit renewals. Form 2A replaces Standard Form A and Short Form A.
POTWs with design influent flows equal to or greater than 100,000 gallons per day (gpd) (0.1 mgd) must
submit Parts A, B, and C of Form 2A. POTWs with design flows of less than 100,000 gpd must submit
Parts A and C of Form 2A. Parts A, B and C are referred to as Basic Application Information:
Part A of Form 2A contains basic application information for all applicants:
- Facility and applicant information.
- Collection system type, areas served, and total population served.
Discharges and other disposal methods.
If the treatment works discharges effluent to waters of the United States, a description of
outfalls, receiving waters, and treatment and effluent testing information.
Part B of Form 2A collects additional information for applicants with a design flow greater than
or equal to 0.1 mgd, including inflow and infiltration estimates, a topographic map, process flow
diagram, and effluent testing data for additional parameters.
Part C is a certification that all applicants must complete.
Form 2A also includes Supplemental Application Information (Parts D-G). POTWs complete these
additional forms, as applicable, depending on the characteristics of the municipal discharge:
Part D requests expanded effluent testing data for metals, volatile organic compounds, acid-
extractable compounds, and base-neutral compounds. A POTW that discharges effluent to waters
of the United States and meets one or more of the following criteria must complete Part D:
- Has a design flow rate greater than or equal to 1 mgd.
- Is required to have a pretreatment program (or has one in place).
Is otherwise required by the permitting authority to provide the information.
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A POTW that meets one or more of the following criteria must complete Part E (Toxicity Testing
Data):
- Has a design flow greater than or equal to 1 mgd.
- Is required to have a pretreatment program (or has one in place).
- Is otherwise required by the permitting authority to submit results of toxicity testing.
A POTW that accepts process wastewater from any significant industrial users (SIUs) or receives
Resource Conservation and Recovery Act (RCRA) or Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA) or other remedial wastes must complete Part F.
SIUs are defined as:
All industrial users subject to Categorical Pretreatment Standards under § 403.6 and 40 CFR
Chapter I, SubchapterN.
Any other industrial user for which any of the following is true
o Discharges an average of 25,000 gpd or more of process wastewater to the POTW
(excluding sanitary, non-contact cooling, and boiler blowdown wastewater).
o Contributes a process wastestream that makes up 5 percent or more of the average dry-
weather hydraulic or organic capacity of the treatment plant.
o Is designated an SIU by the control authority on the basis that it has a reasonable
potential for adversely affecting the POTWs operation or for violating any pretreatment
standard or requirement.
The control authority can determine that an industrial user subject to categorical pretreatment
standards is a nonsignificant categorical industrial user, rather than an SIU, on a finding that
it never discharges more than 100 gpd of total categorical wastewater and if:
o Before that finding, the industrial user has consistently complied with all applicable
categorical pretreatment standards and requirements.
o The industrial user annually submits a certification statement required in § 403.12(q) and
any information necessary to support the certification statement.
o The industrial user never discharges any untreated concentrated wastewater.
If an industrial user meets one of the other criteria for determining that it is an SIU (i.e.,
discharges an average of 25,000 gpd of process wastewater), but the control authority finds
that it has no reasonable potential for adversely affecting the POTW's operation or for
violating any pretreatment standards or requirement, the control authority can determine that
the industrial user is not an SIU.
A POTW that has a combined sewer system must complete Part G. Information that must be
provided in the section includes a system map and diagram, and descriptions of outfalls,
combined sewer overflow (CSO) events, receiving waters, and operations.
4.3.3 Form 2S: New and Existing TWTDS
New TWTDS and TWTDS with effective NPDES permits must submit a new or renewal permit
application, respectively, using new Form 2S . Part 1 of Form 2S is to be
completed by sludge-only facilities; that is, facilities that do not have, and are not applying for, an NPDES
permit for a direct discharge to surface water. Part 1 collects background information on the facility,
including identification information, quantities of sewage sludge handled, pollutant concentrations,
treatment methods, and use and disposal information.
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Part 2 is used by facilities that already have or are applying for an NPDES permit. It includes five
sections:
All applicants using Part 2 must complete the general information collected by section A.
Applicants who either generate sewage sludge or derive a material from sewage sludge must
complete section B.
Applicants who either apply sewage sludge to the land or generate sewage sludge that is applied
to the land by others (unless the sludge from the facility meets certain exemption criteria) must
complete section C.
Applicants who own or operate a surface disposal site must complete section D.
Applicants who own or operate a sewage sludge incinerator must complete section E.
4.3.4 Form 26: New and Existing Concentrated Animal Feeding
Operations (CAFOs) and Concentrated Aquatic Animal Production
(CAAP) Facilities
In addition to Form 1, owners of new and existing CAFOs (defined in § 122.23) and CAAP facilities
(defined in § 122.24) must submit Form 2B .
Form 2B was significantly modified as part of the final CAFO Rules (68 FR 7176, February 12, 2003, and
73 FR 70418, November 20, 2008). The type of information required by Form 2B consists of the following:
For CAFOs
- The name of the owner or operator.
The facility location and mailing addresses.
Latitude and longitude of the production area.
A topographic map of the geographic area in which the CAFO is located.
Specific information about the number and type of animals.
- The type of containment and total capacity for storage (tons/gallons).
- The total number of acres under control of the applicant available for land application.
Estimated amounts of manure, litter, and process wastewater generated and amounts
transferred to other persons per year.
A nutrient management plan (NMP) that satisfies the requirements of § 122.42(e).
For CAAP facilities
The maximum daily and average monthly flow from each outfall.
The number of ponds, raceways, and similar structures.
The name of the receiving water and the source of intake water.
- For each species of aquatic animals, the total yearly and maximum harvestable weight.
- The calendar month of maximum feeding and the total mass of food fed during that month.
Note that recent revisions to the NPDES regulations require that a CAFO seeking coverage under a permit
submit its NMP with its application for an individual permit or notice of intent (NOI) to be authorized
under a general permit. Permitting authorities are required to review the plan and provide the public with
an opportunity for meaningful public review and comment. Permitting authorities also are required to
incorporate terms of the NMP as NPDES permit conditions. For more information on the revisions to the
CAFO regulations, see the Animal Feeding Operations Website .
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Sections 2.3.2.5 and 2.3.2.6 of this manual provide additional information on CAFOs and CAAP
facilities, respectively.
4.3.5 Form 2C: Existing Manufacturing, Commercial, Mining, and
Silvicultural Discharges
In addition to Form 1, operators of existing (i.e., currently permitted) manufacturing, commercial, mining,
and silvicultural discharges must submit Form 2C . The type of
information required in Form 2C includes:
Outfall locations.
A line drawing of the water flow through the facility.
Flow characteristics, sources of pollution, treatment technologies.
Production information (if applicable).
Improvements (if applicable).
Intake and effluent characteristics for conventional, nonconventional and toxic (priority)
pollutants.
Potential discharges not covered by analysis.
Biological testing data.
Contract laboratory information.
Certification and signature.
Quantitative effluent data requirements for existing industrial dischargers vary depending on the industrial
category of the facility, the facility's discharge characteristics and the types of pollutants expected to be
present in the discharge.
4.3.6 Form 2D: New Manufacturing, Commercial, Mining, and Silvicultural
Discharges of Process Wastewater
In addition to Form 1, operators of new manufacturing, commercial, mining, and silvicultural discharges
of process wastewater must submit Form 2D . New dischargers are
those that have not previously obtained permits for a discharge and have not commenced operation. The
type of information required in Form 2D includes the following:
Expected outfall locations.
Date of expected commencement of discharge.
Expected flow characteristics.
Sources of pollutants.
Treatment technologies.
Production information (if applicable).
Expected intake and effluent characteristics.
4.3.7 Form 2E: Manufacturing, Commercial, Mining, and Silvicultural
Facilities that Discharge Only Non-Process Wastewater
In addition to Form 1, operators applying for an individual NPDES permit for manufacturing,
commercial, mining, and silvicultural facilities that are not regulated by effluent limitations guidelines
and standards (effluent guidelines) or new source performance standard, and that discharge only
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non-process wastewaters, must submit Form 2E . Non-process
wastewater includes sanitary wastes, restaurant or cafeteria wastes, and non-contact cooling water, but it
does not include stormwater. Storm water is specifically excluded from the definition of non-process
wastewater. Form 2E also may not be used for discharges by educational, medical, or commercial
chemical laboratories or by POTWs. The type of information required in Form 2E includes the following:
Outfall locations.
Type of waste discharged.
Effluent characteristics, including quantitative data for selected parameters.
Flow characteristics.
Treatment technologies.
4.3.8 Form 2F: Stormwater Discharges Associated with Industrial
Activities
In addition to Form 1, operators applying for an individual NPDES permit for discharges composed
entirely of stormwater associated with industrial activity must submit Form 2F
. Applicants whose discharge is composed of stormwater and non-
stormwater must also submit Form 2C, 2D, or 2E as appropriate. The type of information required in
Form 2F includes the following:
A topographic map and estimates of impervious surface area.
Descriptions of material management practices and control measures.
A certification that outfalls have been evaluated for non-stormwater discharges.
Descriptions of past leaks and spills.
Analytical data from each outfall for several specified parameters.
EPA developed the Guidance Manual For the Preparation of NPDES Permit Applications For
Stormwater Discharges Associated With Industrial Activity1 to assist
operators of facilities that discharge stormwater associated with industrial activity in complying with the
requirements for applying for an NPDES permit.
4.3.9 Stormwater Discharges Associated with Construction Activity
Most stormwater discharges associated with construction activities that result in the disturbance of one
acre or more are covered under a general permit issued by EPA or the authorized state. In cases that a
general permit does not cover the discharge or the discharger decides that an individual permit is
necessary for stormwater discharges associated with construction activity, the discharger is required to
submit Form 1, along with a narrative description of the following:
The location (including a map) and the nature of the construction activity.
The total area of the site and the area of the site that is expected to undergo excavation during the
life of the permit.
Proposed measures, including best management practices (BMPs), to control pollutants in
stormwater discharges during construction, including a brief description of applicable state and
local erosion and sediment control requirements.
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Proposed measures to control pollutants in stormwater discharges that will occur after
construction operations have been completed, including a brief description of applicable state or
local erosion and sediment control requirements.
An estimate of the runoff coefficient of the site and the increase in impervious area after the
construction addressed in the permit application is completed, the nature of fill material and
existing data describing the soil or the quality of the discharge.
The name of the receiving water.
4.3.10 Stormwater Discharges from MS4s Serving a Population Greater
than 100,000
The stormwater application regulations (55 FR 47990, November 16, 1990) require operators of large or
medium MS4s to submit two-part applications. Part 1 application information was required to be
submitted by large MS4s (serving a population greater than 250,000) by November 18, 1991, and by
medium MS4s (serving a population greater than 100,000 but less than or equal to 250,000) by May 18,
1992. Part 2 application information was required to be submitted by large MS4s by November 16, 1992,
and by medium MS4s by May 17, 1993. Those applications could be submitted on a system- or
jurisdiction-wide basis. Key requirements of each part of the application include [and are further
addressed in § 122.26(d)] the following:
Parti
General information (e.g., name, address).
Existing legal authorities to control discharges to the storm sewer system and any additional
authority that might be required.
Source identification information (e.g., storm sewer outfalls, land use information).
- Discharge characterization, including monthly precipitation estimates, average number of
storm events, and results from dry-weather flow screening.
Characterization plan, including identification of 5 to 10 representative outfalls for
stormwater sampling.
- Description of existing stormwater management practices.
- Descriptions of existing budget and resources available to complete Part 2 of the application
and implement the stormwater program.
Part 2
- Demonstration of adequate legal authority.
- Identification of any major storm sewer outfalls not included in Part 1 of the application.
Discharge characterization data from three representative storm events.
Proposed stormwater management program.
Assessment of controls, including expected reductions in pollutant loadings.
- Fiscal analysis, including necessary capital and operation and maintenance expenditures for
each year of the permit.
Under the NPDES regulations, permittees are required to reapply for a new NPDES permit before the
expiration of their existing permit; however, in the case of stormwater permits for MS4s, Part 1 and Part 2
application requirements described above were intended only for the initial issuance of an MS4 permit
and specific requirements for reapplication have not been defined in the regulations. On May 17, 1996,
EPA issued a policy that sets forth a streamlined approach for reapplication requirements for operators of
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MS4s (61 FR41698, August 9, 1996) that allows municipalities to use recommended changes submitted
in their fourth year annual report required under § 122.42(c)(2), as the principal component of their
reapplication package. It also encourages changes to monitoring programs to make them appropriate and
useful to storm water management decisions. With the policy, EPA seeks to improve municipal
stormwater management efforts by allowing municipalities to target their resources for the greatest
environmental benefit.
4.3.11 Stormwater Discharges from Small MS4s
The application requirements for small MS4s are addressed in § 122.33. Most states have issued general
permits for small MS4s; however, regulated small MS4s may seek authorization to discharge under an
individual permit. The application requirements are different depending on whether the MS4 will implement
a program under § 122.34 (i.e., a program that follows EPA's six minimum control measures) or a program
that varies from § 122.34. EPA anticipates that most MS4s will follow the § 122.34 requirements.
Regulated small MS4s seeking an individual permit and wishing to implement a program under § 122.34
(the six minimum control measures) must submit an application to their NPDES permitting authority that
includes the following:
The information required under §§ 122.21(f) and 122.34(d).
An estimate of square mileage served by the small MS4.
Any additional information that the NPDES permitting authority requests.
A storm sewer map that satisfies the requirement of § 122.34(b)(3)(i) will also satisfy the map
requirement in § 122.21(f)(7).
Regulated small MS4s seeking an individual permit and wishing to implement a program that is different
from the program under § 122.34 must comply with the permit application requirements of § 122.26(d)
(for additional information, see section 4.3.10 above). Under § 122.33, the regulated small MS4 is
required to submit both parts of the application requirements in §§ 122.26(d)(l) and (2) by March 10,
2003. Small MS4s are not required to submit the information required by §§ 122.26(d)(l)(ii) and (d)(2)
regarding their legal authority, unless they intend for the permit writer to take such information into
account when developing their other permit conditions. Regulated small MS4s may jointly apply with
another regulated entity consistent with the same requirements.
Additionally, another regulated entity may seek a modification of an existing MS4 permit to include a
regulated small MS4 as a co-permittee. In such a case, the regulated small MS4 must apply consistent
with § 122.26 rather than § 122.34. Application requirements of §§ 122.26(d)(l)(iii) and (iv) and
(d)(2)(iii) do not apply and compliance with §§ 122.26(d)(l)(v) and (d)(2)(iv) can be met by referring to
the other MS4's stormwater management program.
4.3.12 Cooling Water Intake Structures
Phase I of the CWA section 316(b) rule was finalized on December 18, 2001, in 66 FR 65256. The Phase
I Rule (Part 125, Subpart I) implements CWA section 316(b) for most new facilities. The rule applies to
new facilities that use cooling water intake structures to withdraw water from waters of the United States
and that have or require an NPDES permit. This rule includes new facilities that have a design intake flow
of greater than 2 mgd and that use at least 25 percent of water withdrawn for cooling purposes. For other
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new facilities that have or require an NPDES permit but do not meet the 2-mgd intake flow threshold or
use less than 25 percent of their water for cooling water purposes, the permit authority must implement
CWA section 316(b) on a case-by-case basis, using best professional judgment (BPJ) (§§ 125.90(b) and
401.14).
Phase II of the CWA section 316(b) rule was finalized on July 9, 2004, in 69 FR 41576. In 2007 EPA
suspended the rule following remand of a number of its provisions by the U.S. Court of Appeals for the
Second Circuit. CWA section 316(b) requirements for such facilities must be developed on a case-by-case
basis.
Phase III of the CWA section 316(b) rule was finalized on June 16, 2006, in 71 FR 35006. The Phase III
rule (Part 125, SubpartN) implements CWA section 316(b) for new offshore oil and gas extraction
facilities that use cooling water intake structures to withdraw water from waters of the United States and
that have or require an NPDES permit. The rule includes facilities with a design intake flow of greater
than 2 mgd and that use at least 25 percent of water withdrawn for cooling purposes.
EPA has not established national standards for existing Phase III facilities and is reevaluating its decisions
in both Phase II and Phase III because of court remands. In the interim, for Phase III facilities not
regulated under national categorical standards, the permitting authority must implement CWA section
316(b) on a case-by-case basis, using BPJ (§§ 125.90(b) and 401.14). Forthe most current information on
regulatory requirements, see the Cooling Water Intake Structure Program Website
.
4.4 Requirements for NPDES General Permits
As previously discussed in section 3.1.2 of this manual, general permits (§ 122.28) are permits developed
for a specific category of dischargers within a specified geographic or political boundary. Using a general
permit could simplify the permitting process for both EPA and the discharger. Owners/operators may
seek coverage under a general permit only if one has been issued that is applicable to the type of facility
for which coverage is sought and the permit covers the facility's activities. In addition, the permitting
authority may determine that a general permit is not appropriate for a facility seeking coverage under the
general permit and can require the facility to apply for an individual permit. Furthermore, a facility that
otherwise qualifies for a general permit may opt to apply for an individual permit.
In most cases, a facility or activity seeking coverage under a general permit must seek coverage by
submitting an NOI. The information that must be provided by the facility or activity in the NOI is
specified in the general permit and must include, at a minimum, the following:
Legal name and address of the owner or operator.
Name and address of the facility.
Type of facility or discharges.
The receiving stream(s).
EPA has developed the Electronic NOI (eNOI) for construction sites and industrial facilities that need to
apply for coverage under EPA's Construction General Permit (CGP) or Multi-Sector General Permit
(MSGP), respectively. EPA's Electronic Stormwater Notice of Intent (eNOI) Website
presents additional information about eNOI.
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4.5 Application
The contents of individual NPDES permits are based, in part, on the information included in the
application. Thus, the application must be complete and accurate before a permit writer can properly
develop a permit. Exhibit 4-4 depicts the general process for reviewing a permit application, based on a
chart provided in the Washington Department of Ecology's Permit Writers' Manual2.
Exhibit 4-4 Permit application review process
Permit writer receives permit
application
Is the application on the correct form?
Yes
No
Require new application on correct form.
Does the application include all
flow and pollutant data, "N/A" where
appropriate, and required signatures?
No
Yes
Does the application have all of the
information necessary to adequately
characterize the nature and quantity of
pollutants in the effluent and their effect
on the receiving water?
No
Yes
Are all calculations
and flow diagrams correct?
No
Yes
>
Continue to next step in permit
development.
Require and establish schedule for
submittal of required information.
Information submitted
Require and establish schedule for
submittal of additional information.
I
Data submitted
Request clarification or recalculation
and submittal.
J_
Clarification or recalculation submitted
After the initial application review, the permit writer may request that an applicant submit other
information needed to decide whether to issue a permit and for permit development. The requested
information could include the following:
Additional information, quantitative data, or recalculated data.
Submission of a new form (if an inappropriate form was used).
Resubmission of the application (if incomplete or outdated information was initially submitted).
In some situations, a considerable amount of correspondence might be required before the permit writer
obtains all the information that he or she believes is necessary to draft the permit.
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4.5.1 The Complete Application
The regulations at § 122.21(e) state that the Director, "[must] not issue a permit before receiving a
complete application..." At a minimum, the application form must have all applicable spaces filled in.
Instructions for the application form state that all items must be completed and that applicants use the
statement not applicable (N/A) to indicate that the item had been considered. Blanks on a form can occur
for a number of reasons, such as the following:
The response was inadvertently omitted.
The applicant had difficulty determining the correct response and rather than provide misleading
or incorrect information, left the space blank.
The applicant was unwilling to provide the response.
A permit writer must obtain a response to the blank items by contacting the facility in writing or, in some
cases, by telephone. Only minor changes should be handled by telephone and even minor items should be
documented in writing in the permit file. Under no circumstances should a permit writer edit or modify
the application, which is a legal document that has been signed and certified by the applicant. The original
application, any subsequent clarifications, and any supplemental information provided by the applicant
should be clearly identified in the file. The information will become part of the administrative record
(§ 124.9) for the permit (see section 11.2.1 of this manual), which is critical if any legal challenges
regarding permit decisions arise. If the changes or corrections to any application are extensive, the permit
writer may require the permit applicant to submit a new application.
The permit writer may also require supplementary information, such as more detailed production
information or maintenance and operating data for a treatment system, to process the permit. According to
§ 122.21(e), an application is considered complete when the permitting authority is satisfied that all
required information has been submitted. Supplementary information also can be obtained later when the
permit writer is actually drafting the permit. The applicant may submit additional information voluntarily
or be required to do so under CWA section 308 or under a similar provision of state law.
4.5.2 Common Omissions in Applications
This section identifies some of the most common omissions and errors found in NPDES permit
applications and provides examples of ways to identify missing information and verify the accuracy of
certain data.
One of the most commonly omitted items from NPDES permit applications is a topographic map of the
area around the discharge, which is required as an attachment to Form 1, Form 2A, and Form 2S. Other
industry- or municipality-specific information is also often omitted. For example, industrial applicants
sometimes fail to submit a line drawing of the water flow through the facility required by Part II-A of
Form 2C. The line drawing is important for ensuring that the location and description of the outfalls and
the description of processes (Parts I and II-B of Form 2C) provided by the applicant are accurate.
Sometimes applicants do not properly submit the effluent data necessary to characterize the facility.
Below are some required data elements that are commonly omitted from permit applications:
Valid whole effluent toxicity (WET) testing data, required from POTWs with design flows
greater than 1 mgd or those with a pretreatment program. This requirement may be satisfied if the
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expiring permit contains a requirement for effluent characterization of WET. The permit writer
should note the use of this option on the fact sheet.
Biosolids (sewage sludge) monitoring data; a description of biosolids use and disposal
procedures; annual biosolids production volumes; and information on the suitability of the site
and a description of the site management for land application sites from POTWs and other
TWTDS. A land application plan is required for any sites not identified in the application.
Expected toxics and other pollutants. Non-municipal dischargers categorized as primary
industries have some mandatory testing requirements for toxic pollutants (see § 122.21,
Appendix D, Table I and Table II and also listed in Application Form 2C).
Production rates and flow data from industrial facilities that are subject to production- or flow-
based effluent guidelines. Applicants must use units of measure corresponding to applicable
effluent guidelines to allow calculation of effluent limitations.
Appropriate sample types for all required pollutants and parameters being analyzed (Part 136)
(see sections 8.1.4 and 8.3 of this manual for more information). For example, only grab samples
or continuous monitoring may be used for pH, total residual chlorine, and temperature, and only
grab samples may be used for total phenols and volatile organics.
Exhibit 4-5 presents three examples of the types of questions that the permit writer should consider to
determine whether an application is complete.
Exhibit 4-5 Considerations for an application to be complete
Example 1:
A plastics processor submits Form 1 and Form 2C but fails to indicate testing required for any gas
chromatograph/mass spectrometer (GC/MS) fractions in section V.C. of Form 2C and does not provide any data
for these pollutants.
Question:
Did the applicant provide all the required data for the toxic organic pollutants in Form 2C?
Answer:
No. The plastics processor is required to indicate testing required (in the check box) and provide data from at least
one sample for each pollutant in the volatile GC/MS fraction (Table 2C-2 in the application form instructions and
§ 122.21 (g)(7)(v)(A) of the NPDES regulations).
Example 2:
A soap and detergent manufacturing facility in the liquid detergents subcategory submits Form 1 and Form 2C but
marks thallium and beryllium as believed absent in section V.C. of Form 2C and did not provide any data for these
pollutants.
Question:
Is it appropriate for this applicant to mark believed absent in this section of Form 2C?
Answer:
No. Although an applicant that manufactures liquid detergents is not expected to discharge thallium and beryllium,
page 2C-3 of the application form instructions and § 122.21(g)(7)(v)(B) require testing for all listed metals by all
applicants in a primary industry category, such as soap and detergent manufacturers. The indication of believed
absent is incorrect. The applicant should have indicated testing required and provided the results of at least one
sample per pollutant. Occasionally, unexpected contaminants could be present in a wastestream.
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Exhibit 4-5 Considerations for an application to be complete (continued)
Example 3:
An integrated slaughterhouse and meat processing facility submits Form 1 and Form 2C and indicates that zinc is
believed absent from its wastewater.
Question:
Is believed absent a proper indication for zinc for this wastewater?
Answer:
Possibly. After consulting the effluent guidelines development documents for the Meat and Poultry Products Point
Source Category, the permit writer determines that metals, including zinc, are often used as feed additives and in
sanitation products and might be present in the effluent, even though there are no effluent limitations specified for
zinc in the applicable effluent guideline. The permit writer should contact the applicant and clarify whether zinc
would be expected to be present in the discharge.
The comprehensive testing requirements that apply to the various categories of industry are designed to
determine whether any contaminants (some expected, some unexpected) are present in significant
quantities and to determine levels of pollutants that are known to be present. Exhibit 4-6 presents an
example of how a permit writer makes the determination of pollutant data required in the application.
Exhibit 4-6 Example of required testing during application review
Consider the plastics processor and the liquid detergents manufacturer mentioned above, and answer the
following questions:
Question:
What pollutant data are needed to characterize the industries above?
For which toxic organic pollutants are they required to test?
For which heavy metals are they required to test?
Which metals would you expect to find in their wastewaters regardless of whether testing is required?
Answer:
The application form in Table 2C-2 and § 122.21(g)(7)(ii)(A) of the NPDES regulations require testing of the
volatile GC/MS fraction by the plastics processor and the volatile, acid, and base/neutral fractions by the liquid
detergent manufacturer. Page 2C-3 of the application instructions and § 122.21(g)(7)(ii)(B) require testing of all the
metals listed in item V, Part C1 of the application form as well as cyanide and total phenols by both of these
primary industry facilities. For information on which, if any, metals might be expected in wastewater discharged by
these applicants, see the effluent guidelines development documents.
All information submitted on a permit application must be accurate. Although it might be difficult to
detect certain inaccuracies, a number of common mistakes can be readily detected. When mistakes are
detected, they must be corrected. Generally, any correction or edit to the application should be obtained
from the applicant in writing and will become a part of the administrative record for the permit.
In most cases, errors in the application will be inadvertent because of the length and complexity of the
form. Note, however, that the application certification statement indicates, "...that there are significant
penalties for submitting false information, including the possibility of fine and imprisonment for knowing
violations." If the permit writer believes that falsification has occurred, he or she should refer the findings
to the agency's enforcement staff.
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Some of the most common mistakes on permit applications include failing to provide the correct long-
term average and daily maximum values, reporting quantified values below known detection limits, and
using misplaced decimal points or incorrect concentration units. Exhibit 4-7 presents three examples of
the types of questions that the permit writer should consider while reviewing the permit application for
accuracy. Additional guidance from EPA might be available to assist permit writers in reviewing
applications for some of these common errors. For example, an August 23, 2007, memorandum
Analytical Methods for Mercury in National Pollutant Discharge Elimination System (NPDES) Permits^
describes when a method for mercury is sufficiently
sensitive for purposes of permit applications and monitoring under a permit. In the memorandum, EPA
strongly recommends that a permitting authority determine that a permit application that lacks effluent data
analyzed with a sufficiently sensitive EPA-approved method (such as Method 163 IE) is incomplete unless
and until the facility supplements the original application with data analyzed with such a method.
4.6 Facility Information Review
In addition to the submitted application form, the permit writer should assemble other information that
could be used to develop permit limitations and conditions.
4.6.1 Permit File Review
Before developing the draft permit and fact sheet, the permit writer should assemble and review any
additional background information on the facility. If the permit writer is reissuing an existing permit,
much of the information should be available in the permit file. Such information would typically include
The current permit.
The fact sheet or statement of basis for the current permit.
Discharge monitoring reports (DMRs).
Compliance inspection reports.
Engineering reports.
Correspondence or information on changes in plant conditions, problems, and compliance issues.
Much of this information, particularly DMR data, is stored in automated data tracking systems such as
Permit Compliance System (PCS) or state databases.
Integrated Compliance Information System (ICIS)-NPDES .
Online Tracking Information System (OTIS) .
Envirofacts Warehouse .
The permit writer can check with other permit writers who have permitted similar types of facilities to see
if there are any special considerations related to the type of facility to be permitted. A permit writer might
also wish to discuss compliance issues, changes, or history of complaints with compliance personnel who
conducted previous inspections of the facility or with permit writers for other media (e.g., air, solid
waste). Examples of some other sources of information that the permit writer could use for permit
development include the following:
Receiving water quality data from databases such as the EPA STOrage and RETrieval database
(STORET) .
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Exhibit 4-7 Considerations for an application to be accurate
Example 1:
An industrial applicant provides a daily maximum effluent flow value of 50,000 gpd in its permit application Form
2C. However, a review of historical water usage records and an old permit application indicate estimated
wastewater flows ranged from 100,000 to 150,000 gpd. The applicant had not instituted any water use reduction
measures, significantly changed its process operations, or decreased its number of employees.
Question:
Are reported values consistent with historical information?
Answer:
No. An inspection of the facility revealed two separate water meters (one for sanitary and one for process water);
the applicant had overlooked the sanitary meter. Further, the process water meter was found to be defective.
Subsequent flow monitoring of the actual total wastestream recorded a flow of 125,000 gpd. A new water meter
was installed, and concurrent wastestream flow monitoring and water meter readings resulted in the following
water balances:
Water In (based on both water meter readings):
148,000 gpd (131,000 gpd process line and 17,000 gpd sanitary line).
Water Out (based on effluent flow monitoring):
125,000 gpd total treated effluent discharged to the receiving water.
Evaporative and consumption losses were estimated at 23,000 gpd (15% of total water usage).
The permit writer should require the applicant to submit a signed and certified letter with the revised flow estimates
and a new water balance diagram or submit a revised application.
Example 2:
An applicant reported its maximum daily flow as 1.2 mgd, the maximum daily suspended solids concentration as
23 milligrams per liter (mg/L), and the maximum daily mass discharge as 690 pounds per day (Ibs/day).
Question:
Do the concentration, mass, and flow values correspond?
Discussion:
No. Even in the unlikely event that the maximum daily flow and the maximum daily concentration occurred on the
same day, the mass discharged would be well below the reported value of 690 Ibs/day. Using the calculation
below, the mass discharge that corresponds to the solids concentration (23 mg/L) and flow (1.2 mgd) would be
230 Ibs/day:
23 mg/L x 1.2 mgd x 8.34 (lbs)(L)/(mg)(millions of gallons) = 230 Ibs/day
(conversion factor)
Because the applicant reported a maximum mass discharge of 690 Ibs/day, a significant discrepancy is indicated.
The permit writer should contact the applicant to resolve the discrepancy. The applicant should submit a signed
and certified letter clarifying the correct maximum daily mass discharge of suspended solids or submit a revised
application.
Example 3:
The results submitted in the application for total cyanide are all reported as < 1,000 micrograms per liter (ug/L).
When asked, the applicant indicated that total cyanide was analyzed using EPA Method 335.3 (Color, Auto).
Question:
Do concentration values correspond with published method detection limits for the method used?
Answer:
No. EPA Method 335.3 for total cyanide has a published method detection limit (MDL) of 5 ug/L. The applicant
should be able to quantify results for total cyanide at values well below 1,000 ug/L using this method. The
applicant has most likely used Standard Method 4500-CN (titrimetric) for total cyanide, rather than the testing
procedure indicated. If total cyanide is expected to be present in the discharge and would be of concern at effluent
concentrations below 1,000 ug/L, the permit writer should require the applicant to retest for total cyanide using the
more sensitive method and to submit the results in a signed, certified letter.
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Supporting documentation collected by EPA for effluent guidelines and categorical pretreatment
standards for a variety of industrial categories.
Reference textbooks and technical documents that provide information about manufacturing
processes and wastestreams for specific industry categories, which are available from libraries
such as
National Technical Information Service (NTIS) .
- EPA libraries .
Office of Water Resource Center (OWRC) .
National Service Center for Environmental Publications (NSCEP) .
Related environmental permits that could provide site-specific background information about the
types of pollutants and wastestreams at a facility, including, for example
RCRA permits, which regulate the management of hazardous waste by owners and operators
of treatment, storage, and disposal facilities.
Clean Air Act permits, which regulate the discharge of atmospheric pollutants.
EPA's Treatability Manual4, which is a five-volume guidance manual that provides detailed
descriptions of industrial processes, potential pollutants from each process, appropriate treatment
technologies, and cost estimating procedures.
The Toxic Release Inventory (TRI) . which is accessible on EPA's mainframe
and through a public online service. The TRI contains information on more than 300 listed toxic
chemicals released by specific facilities, including chemical identification, quantity of chemicals
released to various environmental media, off-site waste transfer, and waste treatment and
minimization information.
If the permit writer must address special conditions in a permit for a municipal discharger to develop or
implement a pretreatment program or to address discharges other than the wastewater treatment plant
discharge, he or she should obtain the information needed to develop these special conditions. For
example, the permit writer might need information on pretreatment program implementation, combined
sewer overflows (CSOs), sanitary sewer overflows (SSOs), sewage sludge use or disposal, or stormwater
discharges relevant to the facility. Such information is in
Annual pretreatment reports, pretreatment compliance inspections and audits.
CSO reports.
Bypass notifications or SSO reports.
Stormwater discharge applications or NOIs for a general permit.
4.6.2 Facility Site Visits
Facility site visits are an invaluable way to update information on manufacturing processes; obtain
information about the facility's operations, equipment or management; and verify application
information. A site visit also acquaints the permit writer with the people who will be operating under the
permit and participating in the permit development process.
Site visits can also allow the permit writer to gain a better understanding of more complex facilities. Site
visits are especially warranted if significant pollution control or treatment improvements will be required,
if there have been frequent problems in complying with the existing permit, if there are known problems
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with spills or leaks or with contaminated surface runoff, or if there are other unique on-site activities that
could affect the characteristics of the discharge from the facility.
The site visit should include a detailed review of production processes to evaluate the types of toxic or
hazardous substances that might be present in raw materials, products, and by-products. The permit writer
should review the water uses, the resulting wastewater streams, and any in-process pollution controls.
This review is needed to assist in selecting toxic and other pollutants to be limited and in evaluating
possible in-process control improvements.
In addition, the site visit should include a review of the performance and operation and maintenance
practices of wastewater treatment facilities. The review is useful in evaluating the adequacy of existing
treatment performance and assessing the feasibility of improvements in performance. The permit writer
should examine effluent monitoring points, sampling methods, and analytical techniques to identify any
needed changes to monitoring requirements and to evaluate the quality of DMR data.
Raw material and product storage and loading areas, sludge storage and disposal areas, hazardous waste
management facilities, including on-site disposal areas, and all process areas should be observed to
determine the need for controls on surface runoff and specific BMPs. Information from other
environmental programs (e.g., CERCLA or RCRA) might be important in this regard.
While on-site, the permit writer should note any housekeeping problems or the need for spill prevention
actions, which are not usually detectable from permit applications. If allowed, photographs of problem
areas should be taken for future use during permit preparation. If necessary, the permit writer should meet
with management to ask questions or clarify information provided on the permit application. If any
inaccuracies in the application were found because of the site visit, that is the time for the permit writer to
request corrected information.
The time required to conduct a site visit will vary according to the complexity of the facility. For facilities
with only a few basic processes, one main waste treatment system, limited in-process controls, few
surface runoff outfalls, and limited on-site management of sludge or hazardous wastes, an adequate site
visit can most likely be completed in one day. Visits to complex, larger plants with several treatment
systems, numerous outfalls, and extensive ancillary activities may require several days.
Time spent on site visits often results in time savings during permit preparation. However, time and travel
resources might not be adequate to allow visits to all facilities to be permitted. In such cases, the permit
writer might be able to obtain much of the desired information from facility compliance inspections and
should try to coordinate the timing of compliance inspections with the timing of permit development.
Aerial photographs may provide much of the needed information on the potential for contamination of
surface runoff and on ancillary activities without a site visit or inspection. In addition, comparing aerial
photographs with site and process diagrams provided with the application can provide the permit writer
with a complete visual description of the facility. Aerial photographs are available from a variety of
sources, including the U.S. Geological Survey Earth Resources Observation and Science Center
: TerraServer : Google Earth : and other
private contractors.
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4.7 Confidential Information
In accordance with Part 2, information submitted to EPA pursuant to the NPDES permitting regulations
under Part 122 may be claimed as confidential; however, EPA has determined that the following
information will not be held confidential (§ 122.7):
Name and address of the applicant.
Permit applications and information submitted with applications.
Permits.
Effluent data.
Information that may be claimed as confidential includes material related to manufacturing processes
unique to the applicant, or information that might adversely affect the competitive position of the
applicant if released to the public. Under such circumstances, the permit writer will be required to treat
the information as confidential in accordance with the requirements in Part 2. Any claims of
confidentiality must be made at the time of submission or the information will not be considered
confidential.
1 U.S. Environmental Protection Agency. 1991. Guidance Manual For the Preparation of NPDES Permit Applications For
Storm-water Discharges Associated With Industrial Activity. EPA-505/8-91-002. U.S. Environmental Protection Agency, Office
of Water, Washington DC, .
2 Bailey, Gary. 2008. Water Quality Program Permit Writer's Manual. Publication Number 92-109. Washington State
Department of Ecology, Water Quality Program, Olympia, WA.
3 Hanlon, James A. 2007. Analytical Methods for Mercury in National Pollutant Discharge Elimination System (NPDES)
Permits. U.S. Environmental Protection Agency, Office of Wastewater Management. Memorandum, August 23, 2007.
.
4 U.S. Environmental Protection Agency. 1980. TreatabilityManual: Vol. I. Treatabilify Data (EPA-600/8-80-042a) publications
available onNEPIS Website
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CHAPTER 5. Technology-Based Effluent Limitations
One of the major strategies of the Clean Water Act (CWA) in making "reasonable further progress toward
the national goal of eliminating the discharge of all pollutants" is to require effluent limitations based on
the capabilities of the technologies available to control those discharges. Technology-based effluent
limitations (TBELs) aim to prevent pollution by requiring a minimum level of effluent quality that is
attainable using demonstrated technologies for reducing discharges of pollutants or pollution into the
waters of the United States. TBELs are developed independently of the potential impact of a discharge on
the receiving water, which is addressed through water quality standards and water quality-based effluent
limitations (WQBELs). The NPDES regulations at Title 40 of the Code of Federal Regulations (CFR)
125.3(a) require NPDES permit writers to develop technology-based treatment requirements, consistent
with CWA section 301(b), that represent the minimum level of control that must be imposed in a permit.
The regulation also indicates that permit writers must include in permits additional or more stringent
effluent limitations and conditions, including those necessary to protect water quality. As described in
Chapter 7 of this manual, the permit writer might also need to apply anti-backsliding requirements to
determine the final effluent limitations for the NPDES permit.
This chapter discusses development of TBELs for publicly owned treatment works (POTWs) and
industrial (non-POTW) dischargers. Chapter 6 discusses development of WQBELs. Exhibit 5-1 illustrates
the relationship between TBELs and WQBELs in an NPDES permit and the determination of final
effluent limitations.
Exhibit 5-1 Developing effluent limitations
Develop technology-based effluent limitations
(TBELs)
Chapter 5
Develop water quality-based effluent
limitations (WQBELs)
Chapter 6
Determine final effluent limitations that meet
technology and water quality standards and
anti-backsliding requirements
Chapter 7
Chapter 5: Technology-Based Effluent Limitations
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5.1 Technology-based Effluent Limitations for POTWs
The largest category of dischargers requiring individual NPDES permits is POTWs. The federal
regulations at § 403.3(q) define a POTW as a treatment works (as defined in CWA section 212) that is
owned by a state or municipality [as defined in CWA section 502(4)]. Under § 403.3(q), that definition
includes "any devices and systems used in the storage, treatment, recycling and reclamation of municipal
sewage or industrial wastes of a liquid nature." The definition also includes "sewers, pipes, and other
conveyances only if they convey wastewater to a POTW Treatment Plant," as defined in § 403.3(r).
Under § 403.3(q), the term POTW "also means the municipality as defined in section 502(4) of the Act,
which has jurisdiction over the Indirect Discharges to and the discharges from such a treatment works."
CWA section 304(d) required the U.S. Environmental Protection Agency (EPA) to publish information
on the degree of effluent reduction attainable through the application of secondary treatment. Under CWA
section 301(b)(l)(B), in general, POTWs in existence on July 1, 1977, were required to meet discharge
limitations based on secondary treatment (or any more stringent limitations established under state law,
including those necessary to meet state water quality standards). On the basis of those statutory
provisions, EPA developed secondary treatment regulations, which are specified in Part 133. Later
amendments to CWA section 304(d) called for EPA to develop alternative standards for certain types of
POTWs. Those standards are referred to as "equivalent to secondary treatment" standards.
5,1,1 Secondary and Equivalent to Secondary Treatment Standards
Several regulations implement the statutory requirements for developing standards and discharge
limitations based on secondary treatment. EPA has promulgated regulations in Part 133 establishing
secondary treatment standards, equivalent to secondary treatment standards, and a number of special
considerations applied on a case-by-case basis. In addition, § 122.44(a)(l) requires that NPDES permits
include applicable technology-based limitations and standards, while regulations at § 125.3(a)(l) state
that TBELs for POTWs must be based on secondary treatment standards (which includes the "equivalent
to secondary treatment standards") specified in Part 133.
5.1.1.1 Secondary Treatment Standards
In Part 133, EPA published secondary treatment standards based on an evaluation of performance data for
POTWs practicing a combination of physical and biological treatment to remove biodegradable organics
and suspended solids. The regulation applies to all POTWs and identifies the technology-based
performance standards achievable based on secondary treatment for 5-day biochemical oxygen demand
(BOD5), total suspended solids (TSS), and pH. Exhibit 5-2 summarizes the standards.
Exhibit 5-2 Secondary treatment standards
Parameter
BOD5
TSS
BOD5 and TSS removal (concentration)
PH
30-day average
30 mg/L (or 25 mg/L CBOD5)
30 mg/L
not less than 85%
within the lim
7-day average |
45 mg/L (or 40 mg/L CBOD5) j
45 mg/L j
1
ts of 6.0-9.0* |
* unless the POTW demonstrates that: (1) inorganic chemicals are not added to the waste stream as part of the treatment
process; and (2) contributions from industrial sources do not cause the pH of the effluent to be less than 6.0 or greater than 9.0
mg/L = milligrams per liter
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The regulation also includes an alternate set of standards that apply to certain facilities employing waste
stabilization ponds or trickling filters as the principal process. Those standards are called equivalent to
secondary treatment standards.
5.1.1.2 to
Some biological treatment technologies, such as trickling filters or waste stabilization ponds, are capable
of achieving significant reductions in BOD5 and TSS but might not consistently achieve the secondary
treatment standards for these parameters. Congress recognized that unless alternate limitations were set
for facilities with trickling filters or waste stabilization ponds, which often are in small communities, such
facilities could be required to construct costly new treatment systems to meet the secondary treatment
standards even though their existing treatment technologies could achieve significant biological treatment.
To prevent requiring upgrades where facilities were achieving their original design performance levels,
Congress included provisions in the 1981 amendments to the Clean Water Act Construction Grants
program (Public Law 97-117, Section 23) that required EPA to make allowances for alternative biological
treatment technologies, such as a trickling filters or waste stabilization ponds. In response to that
requirement, in 1984, EPA promulgated regulations at § 133.105 that include alternative standards that
apply to facilities using "equivalent to secondary treatment." A facility must meet the criteria in
§ 133.101(g) to qualify for application of those alternative standards.
Equivalent to Secondary Standards
The equivalent to secondary treatment standards, as specified in § 133.105, are shown in Exhibit 5-3.
Exhibit 5-3 Equivalent to secondary treatment standards
30-c
BOD5
not to exceed 45 mg/L
(or not to exceed 40 mg/L CBOD5)
not to exceed 65 mg/L
(or not to exceed 60 mg/L CBOD5)
ITSS
not to exceed 45 mg/L
not to exceed 65 mg/L
BOD5 and TSS removal (concentration)
not less than 65%
* unless the POTW demonstrates that: (1) inorganic chemicals are not added to the waste stream as part of the treatment
process; and (2) contributions from industrial sources do not cause the pH of the effluent to be less than 6.0 or greater than 9.0
Criteria to Qualify for Equivalent to Secondary Standards
To be eligible for discharge limitations based on equivalent to secondary standards, a POTW must meet
all three of the following criteria:
Criterion #1Consistently Exceeds Secondary Treatment Standards: The first criterion that must be
satisfied to qualify for the equivalent to secondary standards is demonstrating that the BOD5 and TSS
effluent concentrations consistently achievable through proper operation and maintenance of the
treatment works exceed the secondary treatment standards set forth in §§ 133.102(a) and (b). The
regulations at§ 133.101 (f) define "effluent concentrations consistently achievable through proper
operation and maintenance" as
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(f)(l): For a given pollutant parameter, the 95th percentile value for the 30-day average effluent
quality achieved by a treatment works in a period of at least 2 years, excluding values attributable
to upsets, bypasses, operational errors, or other unusual conditions.
(f)(2): A 7-day average value equal to 1.5 times the value derived under paragraph (f)(l).
Some facilities might meet this criterion only for the BOD5 limitations or only for the TSS
limitations. EPA believes that it is acceptable for the permit writer to adjust the limitations for only
one parameter (BOD5 or TSS) if the effluent concentration of only one of the parameters is
demonstrated to consistently exceed the secondary treatment standards.
Criterion #2Principal Treatment Process: The second criterion that a facility must meet to be
eligible for equivalent to secondary standards is that its principal treatment process must be a trickling
filter or waste stabilization pond (i.e., the largest percentage of BOD and TSS removal is from a
trickling filter or waste stabilization pond system).
Criterion #3Provides Significant Biological Treatment: The third criterion for applying equivalent
to secondary standards is that the treatment works provides significant biological treatment of
municipal wastewater. The regulations at § 133.101(k) define significant biological treatment as
using an aerobic or anaerobic biological treatment process in a treatment works to consistently
achieve a 30-day average of at least 65 percent removal of BOD5.
A permit writer should consider each facility on a case-by-case basis to determine whether it meets those
three criteria. To apply the criteria, the permit writer should assemble enough influent, effluent, and flow
data from the facility to adequately characterize the facility's performance or require the discharger to
provide an appropriate analysis. If the facility has made substantial changes in its operations or treatment
processes during the current permit term, the permit writer, using his or her best professional judgment
(BPJ), may elect to use data for a period that is representative of the discharge at the time the permit is
being drafted. Facilities that do not meet all three criteria do not qualify as equivalent to secondary
treatment facilities. For such facilities, the secondary treatment standards apply. EPA noted in its
December 1985 Draft Guidance for NPDES Permits and Compliance PersonnelSecondary Treatment
Redefinition1 that a treatment works operating beyond its design hydraulic or organic loading limit is not
eligible for application of equivalent to secondary standards. If overloading or structural failure is causing
poor performance, the solution to the problem is construction, not effluent limitations adjustment.
5.1.2 Adjustments to Equivalent to Secondary Standards
In addition to providing secondary treatment standards and equivalent to secondary treatment standards,
the federal regulations allow states to make adjustments to the standards and to apply those adjusted
standards on a case-by-case basis.
5.1.2.1 Adjusted TSS Requirements for Waste Stabilization Ponds
In accordance with regulations adopted by EPA in 1977 and revised in 1984, states can adjust the
maximum allowable TSS concentration for waste stabilization ponds upward from those specified in the
equivalent to secondary treatment standards to conform to TSS concentrations achievable with waste
stabilization ponds. The regulation, found at § 133.103(c), defines "SS concentrations achievable with
waste stabilization ponds" as the effluent concentration achieved 90 percent of the time within a state or
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appropriate contiguous geographical area by waste stabilization ponds that are achieving the levels of
effluent quality for BOD5 specified in § 133.105(a)(l) (45 milligrams per liter [mg/L] as a 30-day
average). To qualify for an adjustment up to as high as the maximum concentration allowed, a facility
must use a waste stabilization pond as its principal process for secondary treatment and its operations and
maintenance data must indicate that it cannot achieve the equivalent to secondary standards. EPA has
published approved alternate TSS requirements in 49 Federal Register (FR) 37005, September 20, 1984.
Exhibit 5-4 is a summary from the FR notice of the adjusted TSS requirements for each state.
Location
Exhibit 5-4 State-specific adjusted TSS requirements*
Alternate TSS
limitation
(30-day average)
(mg/L) Location
Alternate TSS
limitation
(30-day average)
(mg/L)
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Aerated ponds
All others
Connecticut
Delaware
District of Columbia
Florida
Georgia
Guam
Hawaii
Idaho
Illinois
Indiana
Iowa
Controlled discharge,
3 cell
All others
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan:
Controlled seasonal
discharge
Summer
Winter
Minnesota
Mississippi
Missouri
Montana
90
70
90
90
95
75
105
None
None
None
None
90
None
None
None
37
70
Case-by-case but
not greater than 80
80
80
None
90
45
90
None
70
40
40
None
80
100
Nebraska
North Carolina
North Dakota
North and east of Missouri R.
South and west of Missouri R.
Nevada
New Hampshire
New Jersey
New Mexico
New York
Ohio
Oklahoma
Oregon
East of Cascade Mountains
West of Cascade Mountains
Pennsylvania
Puerto Rico
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
East of Blue Ridge Mountains
West of Blue Ridge Mountains
East slope counties: Loudoun,
Fauquier, Rappahannock, Madison,
Green, Albemarle, Nelson,
Amherst, Bedford, Franklin, Patrick.
Virgin Islands
Washington
West Virginia
Wisconsin
Wyoming
Trust Territories and N. Marianas
80
90
60
100
90
45
None
90
70
65
90
85
50
None
None
45
90
120
100
90
None
55
60
78
Case-by-case
application of 60/78
limits
None
75
80
80
100
None
* (49 FR 37005, September 20, 1984)
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5,1,2,2
To further address the potential variations in facility performance arising from geographic, climatic, or
seasonal conditions in different states, the revised secondary treatment regulations (adopted in 1984) also
included provisions in § 133.105(d) for ASRs. The ASR provisions give states flexibility to modify the
maximum allowable concentrations of both BOD5 and TSS for trickling filter facilities and for BOD5 for
waste stabilization pond facilities. ASRs are set at levels consistently achievable through proper operation
and maintenance [§ 133.101(f)] by the median facility in a representative sample of facilities within a
state or appropriate continuous geographical area that meet the definition of facilities eligible for
treatment equivalent to secondary treatment. Qualifying facilities are eligible to receive limitations up to
the concentrations specified by the ASRs.
5.1.3 to
and
Determining whether secondary treatment standards or equivalent to secondary standards apply to a
POTW and determining the specific discharge limitations for the facility based on either set of standards
and any other special considerations that might apply can be a complex process. Permit writers should
remember that compliance with limitations must be measurable and percent removal limitations require
influent monitoring (for more on establishing monitoring conditions, see section 8.1 of this manual). This
section presents a step-by-step procedure to establishing technology-based effluent limitations for
POTWs as shown in Exhibit 5-5.
Exhibit 5-5 Steps to establish technology-based discharge limitations for POTWs
Step 1. Determine whether secondary treatment standards or equivalent to secondary treatment
standards or adjusted standards apply
Step 2. Calculate effluent limitations based on secondary treatment standards or
Step 3. Calculate effluent limitations based on equivalent to secondary standards or
Step 4. Calculate effluent limitations based on adjusted standards
Step 5. Apply special considerations for further adjustments
Step 6. Document the application of secondary or equivalent to secondary treatment standards or
adjusted standards and all special considerations in the fact sheet
5,1,3,1 1: or to
Treatment or
The first step for permit writers to develop TBELs for municipal dischargers is to determine whether
secondary treatment standards (discussed in section 5.1.1 above), equivalent to secondary standards
(discussed in section 5.1.1.2 above), or some adjustments to the equivalent to secondary standards
(discussed in section 5.1.2 above) apply to the POTW.
An important consideration for permitting authorities is how to treat new POTW discharges that use a
waste stabilization pond or trickling filter, or a combination of the two. New facilities or new discharges
from trickling filters or waste stabilization ponds often are capable of achieving secondary treatment
standards. In the preamble to the secondary treatment regulation (49 FR 37002, September 20, 1984) and
in § 133.105(f)(2), EPA noted that when developing permits for new trickling filter and waste
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stabilization pond facilities, permitting authorities should consider the ultimate design capability of the
treatment process, geographical and climatic conditions, and the performance capabilities of recently
constructed facilities in similar situations.
After determining whether secondary treatment standards or equivalent to secondary treatment standards
apply to a facility or a discharge, the permit writer applies the appropriate standards to develop effluent
limitations. Section 5.1.3.2 below (Step 2) details development of effluent limitations for facilities or
discharges where secondary treatment standards apply; section 5.1.3.3 below (Step 3) details development
of limitations for facilities that qualify for equivalent to secondary standards; and section 5.1.3.4 below
(Step 4) details development of limitations for facilities where adjusted standards apply. It is possible that
a facility with multiple biological treatment processes could have limitations based on a combination of
the standards (see section 5.1.3.5 below [Step 5]); therefore, those sections are presented as separate steps.
5.1.3.2 2: on
If the facility being permitted is subject to the secondary treatment standards, the permit writer should
complete Step 2. Otherwise, he or she should move to Step 3 in section 5.1.3.3 below.
Applying the secondary treatment standards in NPDES permits is straightforward. Where secondary
treatment standards apply, the permit should include effluent limitations in the permit as presented in
Exhibit 5-6 below, consistent with the secondary treatment standards and the regulatory requirements in
§ 122.45(d)(2).
Exhibit 5-6 Effluent limitations calculated from secondary treatment standards
\f semeaieeem. ...................................................................................................................... ..mmmmmmmmmmmmmmmmmmmmmmmmmmmmeemeaieeaieeem. .-..................... ..mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmeemeaiei^
': Parameter
Average monthly limitation Average weekly limitation
| BOD5
|TSS
!BOD5 and TSS removal (concentration)
PH
30 mg/L (or 25 mg/L CBOD5)
30 mg/L
not less than 85%
45 mg/L (or 40 mg/L CBOD5) j
45 mg/L j
N/A |
Within the range of 6.0-9.0 standard units at all times (or expressed j
as instantaneous minimum and maximum limitations)* j
* unless the POTW demonstrates that: (1) inorganic chemicals are not added to the waste stream as part of the treatment
process; and (2) contributions from industrial sources do not cause the pH of the effluent to be less than 6.0 or greater than 9.0
Certain provisions in the EPA regulations warrant some clarification.
First, the secondary treatment standards are stated as 30-day and 7-day averages, whereas § 122.45(d)(2)
requires that effluent limitations for POTWs be expressed, unless impracticable, as average monthly and
average weekly limitations. The NPDES regulations in § 122.2 define average monthly and average
weekly limitations on a calendar period basis. Therefore, EPA recommends that permit writers apply the
30-day and 7-day average secondary treatment standards directly as average monthly (calendar month)
and average weekly (calendar week) discharge limitations.
Second, § 122.45(f)(l) requires that all permit limitations, standards, or prohibitions be expressed in
terms of mass except in any of the following cases:
For pH, temperature, radiation or other pollutants that cannot appropriately be expressed by mass
limitations.
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When applicable standards and limitations are expressed in terms of other units of measure.
If in establishing permit limitations on a case-by-case basis under § 125.3, limitations expressed
in terms of mass are infeasible because the mass of the pollutant discharged cannot be related to a
measure of operation, and permit conditions ensure that dilution will not be used as a substitute
for treatment.
The first condition applies to pH requirements established by secondary treatment standards. In addition,
because the 30-day and 7-day average requirements for BOD5 and TSS, including percent removal, are
expressed in terms of concentration, the second condition applies to the standards. Thus, mass-based
discharge limitations are not specifically required to implement secondary treatment standards; however,
permit writers can choose to include mass-based limitations in a permit. In general, regulations at
§ 122.45 (b)(l) require using the design flow rate of the POTW to calculate limitations. To calculate a
mass-based limitation for a POTW (in pounds per day [Ibs/day]) a permit writer would use the equation
and follow the example calculations in Exhibit 5-7.
Exhibit 5-7 POTW mass based limitation calculation equation and example calculations
POTW design flow
in million gallons per day
(mgd)
Concentration-based limitation
in milligrams per liter
(mg/L)
Conversion factor
8.34 with units of
(lbs)(L) / (mg)(millions of gallons)
A POTW with a design flow of 2.0 mgd would have mass-based limitations calculated from secondary treatment
standards as follows:
Mass-based limitation* =
BOD5
Average monthly =
Average weekly =
TSS
Average monthly =
Average weekly =
POTW design flow x Concentration-based limitation x Conversion factor
2.0 mgd x 30 mg/L x 8.34 (lbs)(L)/(mg)(millions of gallons) = 500 Ibs/day
2.0 mgd x 45 mg/L x 8.34 (lbs)(L)/(mg)(millions of gallons) = 750 Ibs/day
2.0 mgd x30mg/Lx 8.34 (lbs)(L)/(mg)(millions of gallons) = 500 Ibs/day
2.0 mgd x45mg/Lx 8.34 (lbs)(L)/(mg)(millions of gallons) = 750 Ibs/day
1 calculated to 2 significant figures
5.1.3.3 3: on to
Standards
If a facility being permitted is subject to the equivalent to secondary standards without any further
adjustments by the state (e.g., ASRs), the permit writer should complete Step 3. Otherwise, he or she
should move to Step 4 in section 5.1.3.4 below.
For facilities that qualify for equivalent to secondary standards, effluent limitations must meet the
requirements specified in § 133.105 and summarized above in Exhibit 5-3 (not accounting for any further
approved adjustments). It is important to note that the equivalent to secondary standards specify the
maximum allowable discharge concentration of BOD5 and TSS and a minimum percent removal
requirement for qualified facilities. The regulations at § 133.105(f) require a permitting authority to
include more stringent limitations when it determines that the 30-day average and 7-day average BOD5
and TSS concentrations are achievable through proper operation and maintenance of the treatment works
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(based on an analysis of the past performance for an existing facility or considering the design capability
of the treatment process and geographical and climatic conditions for a new facility) would enable the
treatment works to achieve more stringent limitations than the least stringent effluent quality allowed by
the equivalent to secondary standards. As noted above, the regulations at § 133.101(f) define, "effluent
concentrations consistently achievable through proper operation and maintenance" as the 95th percentile
value for the 30-day average effluent quality achieved by a treatment works in a period of at least 2 years,
excluding values attributable to upsets, bypasses, operational errors, or other unusual conditions. The
7-day average value is set equal to 1.5 times the 30-day average value.
If an existing facility does not have sufficient data to establish past performance, the permit writer could
include the limitations from the previous permit in the new permit and require monitoring to generate the
necessary data. In addition, the permit writer could choose to include a provision allowing the permitting
authority to reopen and, if necessary, modify the permit after reviewing the additional data collected by
the discharger.
As with limitations based on secondary treatment standards (shown in Exhibit 5-6 above), limitations
based on equivalent to secondary standards are expressed as average monthly (calendar month) and
average weekly (calendar week) limitations. Mass-based limitations can be calculated using the
procedures outlined above.
5.1.3.4 Step 4: Calculate Effluent Limitations Based on Adjusted Standards
If a facility being permitted is subject to the adjusted standards as described in section 5.1.2 above, the
permit writer should complete Step 4. Otherwise, he or she should move to section 5.1.3.5 below (Step 5).
As discussed in sections 5.1.2.1 and 5.1.2.2 above, the federal regulations at § 133.103(c) allow states to
adjust the maximum allowable discharge concentration of TSS for waste stabilization ponds upward from
what would otherwise be required by the equivalent to secondary standards, and the regulations at
§ 133.105(d) give states flexibility to adopt ASRs that modify equivalent to secondary requirements for
both BOD5 and TSS for trickling filter facilities and BOD5 requirements for waste stabilization pond
facilities. Where one or more of the adjusted standards apply, average monthly limitation(s) generally
should be set at the lower of the following:
The 30-day average concentration of the pollutant that could be achievable through proper
operation and maintenance of the treatment works.
The maximum concentration of the pollutant that would be allowed under the adjusted standard.
Permit writers should note, however, that if the state has developed an adjusted TSS standard for waste
stabilization ponds consistent with § 133.103(c), the regulations would allow uniform application of that
standard to POTWs where waste stabilization ponds are the principal process used for secondary
treatment and operation and maintenance data indicate that the equivalent to secondary treatment
standards for TSS cannot be achieved.
The average weekly limitation can be set equal to 1.5 times the average monthly limitation and mass-
based limitations may be calculated using the procedures outlined above.
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5.1.3.5 Step 5: Apply Special Considerations for Further Adjustments
Part 133 allows a permit writer to make further adjustments when calculating effluent limitations derived
from secondary treatment standards or equivalent to secondary standards based on several special
considerations. The permit writer should determine whether any of the special considerations outlined in
this section apply and, as appropriate, make any further adjustments to the concentration limitations or
percent removal requirements. The calculated limitations, after making such adjustments, are the final
technology-based effluent limitations for the POTW.
Substitution of CBOD5 for BOD5
Wastewater contains carbonaceous oxygen demanding substances and nitrogenous oxygen demanding
substances. A CBOD5 test measures the 5-day carbonaceous biochemical oxygen demand while the BOD5
test measures the both carbonaceous biochemical oxygen demand and nitrogenous biochemical oxygen
demand. During nitrification, nitrifying bacteria use a large amount of oxygen to consume nitrogenous
oxygen demanding substances (unoxidized nitrogen and ammonia-nitrogen) and convert these to oxidized
nitrate. For wastewaters with significant nitrogen content, basing permit limitations on CBOD5 instead of
BOD5 eliminates the impact of nitrification on discharge limitations and compliance determinations. EPA
recognizes that the CBOD5 test can provide accurate information on treatment plant performance in many
cases and, in Part 133, allows permit writers to use CBOD5 limitations in place of BOD5 limitations to
minimize false indications of poor facility performance as a result of nitrogenous oxygen demand.
EPA has established CBOD5 standards for cases where secondary treatment standards or equivalent to
secondary treatment standards are applied:
Secondary Treatment: The CBOD5 secondary treatment performance standards specified by the
regulations are as follows:
25 mg/L as a 30-day average.
40 mg/L as a 7-day average.
The EPA-approved test procedures in Part 136 include a CBOD5 (nitrogen inhibited) test
procedure. Subject to any state-specific requirements, a permit writer can specify these CBOD5
limitations along with CBOD5 monitoring requirements in any POTW permit requiring
performance based on secondary treatment standards [§ 133.102(a)(4)].
Equivalent to Secondary Treatment: The CBOD5 equivalent to secondary treatment
performance standards specified by the regulations are as follows:
No greater than 40 mg/L as a 30-day average.
- No greater than 60 mg/L as a 7-day average.
Where data are available to establish CBOD5 limitations, and subject to any state-specific
requirements, a permit writer may substitute CBOD5 for BOD5 and specify CBOD5 limitations
and monitoring requirements when applying equivalent to secondary standards.
Substitution of COD or TOC for BOD5
Chemical oxygen demand (COD) and total organic carbon (TOC) laboratory tests can provide an accurate
measure of the organic content of wastewater in a shorter time frame than a BOD5 test (i.e., several hours
versus five days). The regulations at § 133.104(b) allow a permit writer to set limitations for COD or
TOC instead of BOD5 if a long-term BOD5:COD or BOD5:TOC correlation has been demonstrated.
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Adjustments for Industrial Contributions
Under § 133.103(b), treatment works receiving wastes from industrial categories with effluent limitations
guidelines and standards (effluent guidelines) requirements or new source performance standards for
BOD5 or TSS, which are less stringent than the secondary treatment standards or, if applicable, the
equivalent to secondary treatment standards in Part 133, can qualify to have their 30-day BOD5 or TSS
limitations adjusted upward provided that the following are true:
The adjusted 30-day limitations are not greater than the limitations in effluent guidelines or new
source performance standards, as applicable, for the industrial category.
The flow or loading of BOD5 or TSS introduced by the industrial category exceeds 10 percent of
the design flow or loading to the POTW.
When making this adjustment, the Part 133 values for BOD5 and TSS should be adjusted proportionately.
Accordingly, a permit writer should make the adjustment using a flow-weighted or loading-weighted
average of the two concentration limitations (i.e., the limitations developed from effluent guidelines for
the industrial facility and the secondary or equivalent to secondary limitations).
Adjustments to Percent Removal Requirements
The 85 percent removal requirement (for a 30-day average) in secondary treatment standards was
originally established to achieve two basic objectives:
To encourage municipalities to remove high quantities of infiltration and inflow (I/I) from their
sanitary sewer systems.
To prevent intentional dilution of influent wastewater.
In facilities with dilute influent that is not attributable to high quantities of I/I or intentional dilution, the
percent removal requirement could result in forcing advanced treatment rather than the intended
secondary treatment. Advanced treatment generally refers to treatment processes following secondary
treatment (e.g., filtration, chemical addition, or two-stage biological treatment). Advanced treatment can
achieve significantly greater pollutant removals than secondary treatment processes but at a higher cost.
The regulations at §§ 133.103(a), (d) and (e) provide that, under certain circumstances, permit writers
may set less stringent limitations for BOD5 and TSS percent removal. The specific circumstances and the
potential adjustments to the percent removal requirement are as follows:
Treatment works that receive less concentrated wastes from combined sewer systems are
eligible to have less stringent monthly percent removal limitations during wet-weather events
[§ 133.103 (a)] and, under certain conditions, less stringent percent removal requirements or a
mass loading limitation instead of a percent removal requirement during dry weather [§ 133.103
(e)]. The permit writer must determine on a case-by-case basis whether any attainable percentage
removal level can be defined during wet weather and, if so, what the level should be. To qualify
for a less stringent percent removal requirement or substitution of a mass limitation during dry
weather, the discharger must satisfactorily demonstrate the following:
1. The facility is consistently meeting, or will consistently meet, its permit effluent
concentration limitations, but cannot meet its percent removal limitations because of less
concentrated influent. A permitting authority should consider establishing criteria for
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documenting what constitutes consistently meeting concentration limitations and what
constitutes being unable to meet percent removal limitations because of less concentrated
influent.
2. To meet the percent removal requirements, the facility would have to achieve significantly
more stringent effluent concentrations than would otherwise be required by the concentration-
based standards. Each permitting authority also should consider establishing criteria for
demonstrating that this condition is met (e.g., because of dilute influent, X percent of the time
a discharger would be forced to meet concentration requirements that are X percent more
stringent than the concentration limitations otherwise applicable to satisfy the percent
removal requirements).
3. The less concentrated influent wastewater does not result from either excessive infiltration or
clear water industrial discharges during dry weather periods. The determination of whether
the less concentrated wastewater results from excessive infiltration is discussed in regulations
at § 35.2005(b)(28). This regulation defines nonexcessive infiltration as the quantity of flow
that is less than 120 gallons per capita per day (domestic base flow and infiltration) or the
quantity of infiltration that cannot be economically and effectively eliminated from a sewer
system as determined in a cost-effectiveness analysis. The regulations at § 133.103(e) include
the additional criterion that either 40 gallons per capita per day or 1,500 gallons per inch
diameter per mile of sewer may be used as the threshold value for that portion of dry-weather
base flow attributed to infiltration. If the less concentrated influent wastewater is the result of
clear water industrial discharges, then the treatment works must control such discharges
pursuant to Part 403.
Treatment works that receive less concentrated wastes from separate sewer systems can
qualify to have less stringent percent removal requirement or receive a mass loading limitation
instead of the percent removal requirement provided the treatment plant demonstrates all of the
following [§ 133.103(d)]:
1. The facility is consistently meeting or will consistently meet its permit effluent concentration
limitations but cannot meet its percent removal limitations because of less concentrated
influent wastewater. For additional detail on this criterion, see discussion above for combined
sewers during dry weather.
2. To meet the percent removal requirements, the facility would have to achieve significantly
more stringent limitations than would otherwise be required by the concentration-based
standards. For additional detail on this criterion, see the discussion above for combined
sewers during dry weather.
3. The less concentrated influent wastewater does not result from excessive infiltration and
inflow (I/I). The regulation indicates that the determination of whether the less concentrated
wastewater is the result of excessive I/I will use the definition of excessive I/I at
§ 35.2005(b)(16), plus the additional criterion that flow is nonexcessive if the total flow to the
POTW (i.e., wastewater plus inflow plus infiltration) is less than 275 gallons per capita per
day. The regulation at § 35.2005(b)(16) defines excessive I/I as the quantities of I/I that can
be economically eliminated from a sewer system as determined in a cost-effectiveness
analysis that compares the costs for correcting the I/I conditions to the total costs for
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transportation and treatment of the I/I. This regulation also refers to definitions of
nonexcessive I/I in §§ 35.2005(b)(28) and 35.2005(b)(29).
Secondary Treatment Variance for Ocean DischargeCWA Section 301 (h) Variance
CWA section 301(h) provides for variances from secondary treatment standards for POTWs that
discharge into ocean waters if the modified requirements do not interfere with attainment or maintenance
of water quality. Permit writers should note that the deadline to apply for a CWA section 301(h) variance
(December 29, 1982) has passed, thus no new facilities may apply for this variance.
Eligible POTW applicants meeting the set of environmentally stringent criteria in CWA section 301(h)
receive a modified NPDES permit waiving the secondary treatment requirements for the conventional
pollutants of BOD5, TSS, and pH. EPA issued regulations, developed the Amended Section 301(h)
Technical Support Document2, and prepared a website titled Amendments to Regulations Issued, the
Clean Water Act Section 301 (h) Program . EPA has
promulgated specific regulations pertaining to CWA section 301(h) that are provided in Part 125,
Subpart G.
All CWA section 301(h) variance modified permits must contain the following specific permit conditions:
Effluent limitations and mass loadings that will assure compliance with Part 125, Subpart G.
Requirements for pretreatment program development, a nonindustrial toxics control program, and
control of combined sewer overflows.
Monitoring program requirements that include biomonitoring, water quality, and effluent
monitoring.
Reporting requirements that include the results of the monitoring programs.
No new or substantially increased discharges from the point source of the affected pollutant can be
released above that volume of discharge specified in the permit.
5.1.3.6 Step 6: Document the Application of Secondary or Equivalent to Secondary
Treatment Standards and all Adjustments and Considerations in the Fact Sheet
Permit writers need to document their application of secondary or equivalent to secondary treatment
standards in the NPDES permit fact sheet for municipal facilities. The permit writer should clearly
identify the data and information used to determine whether secondary treatment standards or equivalent
to secondary treatment standards or adjusted standards apply and how that information was used to derive
effluent limitations for the permit. The permit writer should also note all adjustments and special
considerations in the fact sheet. The information in the fact sheet should provide the NPDES permit
applicant and the public a transparent, reproducible, and defensible description of how the NPDES permit
properly incorporates secondary treatment standards.
5.2 Technology-Based Effluent Limitations for Industrial
(Non-POTW) Dischargers
EPA is required to promulgate technology-based limitations and standards that reflect pollutant reductions
that can be achieved by categories, or subcategories, of industrial point sources using specific
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technologies (including process changes) that EPA identifies as meeting the statutorily prescribed level of
control under the authority of CWA sections 301, 304, 306, 307, 308, 402, and 501 (33 United States
Code [U.S.C.] 1311, 1314, 1316, 1318, 1342, and 1361). Those national industrial wastewater controls
are called effluent limitations guidelines and standards (effluent guidelines). Unlike other CWA tools,
such as water quality standards, effluent guidelines are national in scope and establish performance
standards for all facilities within an industrial category or subcategory.
For point sources that introduce pollutants directly into the waters of the United States (direct
dischargers), the effluent guidelines promulgated by EPA are implemented through NPDES permits as
authorized in CWA sections 301(a), 301(b), and 402. For sources that discharge to POTWs (indirect
dischargers), EPA promulgates pretreatment standards that apply directly to those sources and are
enforced by POTWs and state and federal authorities as authorized in CWA sections 307(b) and (c).
When developing TBELs for industrial (non-POTW) facilities, the permit writer must consider all
applicable technology standards and requirements for all pollutants discharged. Without applicable
effluent guidelines for the discharge or pollutant, permit writers must identify any needed TBELs on a
case-by-case basis, in accordance with the statutory factors specified in CWA sections 301(b)(2) and
304(b). The site-specific TBELs reflect the BPJ of the permit writer, taking into account the same
statutory factors EPA would use in promulgating a national effluent guideline regulation, but they are
applied to the circumstances relating to the applicant. The permit writer also should identify whether state
laws or regulations govern TBELs and might require more stringent performance standards than those
required by federal regulations. In some cases, a single permit could have TBELs based on effluent
guidelines, BPJ, and state law, as well as WQBELs based on water quality standards.
Sections 5.2.1 and 5.2.2 below provide an overview of effluent guidelines and development of TBELs in
NPDES permits using the effluent guidelines. Section 5.2.3 below discusses the development of TBELs
in the absence of effluent guidelines (i.e., case-by-case limitations developed using BPJ).
5.2.1
Congress saw the creation of a single national pollution control requirement for each industrial category,
based on the best technology the industry could afford, as a way to reduce the potential creation of
pollution havens and to attain a high-level water quality in the nation's waters. Consequently, EPA's goal
in establishing effluent guidelines is to ensure that industrial facilities with similar characteristics will
meet similar effluent limitations representing the best pollution control technologies or pollution
prevention practices regardless of their location or the nature of the receiving water into which the
discharge is made. In establishing the effluent guidelines, EPA must consider the industry-wide economic
achievability of implementing the technology and the incremental costs in relation to the pollutant-
reduction benefits.
Effluent guidelines can include numeric and narrative limitations, including best management practices
(BMPs), to control the discharge of pollutants from categories of point sources. The limitations are based
on data characterizing the performance of technologies available and, in some cases, from modifying
process equipment or the use of raw materials. Although the regulations do not require the use of any
particular treatment technology, they do require facilities to achieve effluent limitations that reflect the
proper operation of the model technologies selected as the basis for the effluent guidelines and from
which the performance data were obtained to generate the limitations. Therefore, each facility has the
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discretion to select any technology design and process changes necessary to meet the performance-based
discharge limitations and standards specified by the effluent guidelines.
As of the date of this manual's publication, EPA has issued effluent guidelines for 56 industrial
categories, which apply to between 35,000 and 45,000 facilities that discharge directly to waters of the
United States and another 12,000 facilities that discharge into POTWs. The regulations prevent the
discharge of more than 1.2 billion pounds of toxic (priority) and nonconventional pollutants each year.
EPA's Effluent Guidelines Program Website provides information on existing
effluent guidelines, current effluent guidelines rulemaking, and the effluent guidelines planning process.
5.2.1.1 for
The CWA directs EPA to promulgate effluent guidelines reflecting pollutant reductions that can be
achieved by existing facilities in categories or subcategories of industrial point sources using specific
control technologies. In addition, EPA is required to develop effluent guidelines for new sources. Those
levels of control are summarized below and in Exhibit 5-8.
Exhibit 5-8 Summary of CWA technology levels of control
Type of sites regulated BPT BCT ~ BAT NSPS PSES
PSNS
Existing Direct Dischargers
New Direct Dischargers
Existing Indirect Dischargers
New Indirect Dischargers
X
X
X
X
X
1
x !
Pollutants regulated BPT BCT BAT NSPS PSES PSNS J
Conventional Pollutants
Nonconventional Pollutants
Toxic (Priority) Pollutants
X
X
X
X
X
X
X
X
X
X
X
x I
x l
Best Practicable Control Technology Currently Available (BPT)
BPT is the first level of technology-based effluent controls for direct dischargers and it applies to all types
of pollutants (conventional, nonconventional, and toxic). The Federal Water Pollution Control Act
(FWPCA) amendments of 1972 require that when EPA establishes BPT standards, it must consider the
industry-wide cost of implementing the technology in relation to the pollutant-reduction benefits. EPA
also must consider the age of the equipment and facilities, the processes employed, process changes,
engineering aspects of the control technologies, non-water quality environmental impacts (including
energy requirements), and such other factors as the EPA Administrator deems appropriate [CWA section
304(b)(l)(B)]. Traditionally, EPA establishes BPT effluent limitations on the basis of the average of the
best performance of well-operated facilities in each industrial category or subcategory. Where existing
performance is uniformly inadequate, BPT may reflect higher levels of control than currently in place in
an industrial category if the Agency determines that the technology can be practically applied. See CWA
sections 301(b)(l)(A) and 304(b)(l)(B).
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Best Conventional Pollutant Control Technology (BCT)
The 1977 CWA requires EPA to identify effluent reduction levels for conventional pollutants associated
with BCT for direct discharges from existing industrial point sources. As with BPT, when establishing
BCT the Agency considers the age of the equipment and facilities, the processes employed, process
changes, engineering aspects of the control technologies, non-water quality environmental impacts
(including energy requirements), and such other factors as the EPA Administrator deems appropriate
[CWA section 304(b)(4)(B)]. In addition, EPA also considers a two-part cost reasonableness test, as
required by CWA section 304(b)(4)(B), which includes (1) consideration of the reasonableness of the
relationship between the costs of attaining a reduction in effluent and the effluent reduction benefits
derived and (2) a comparison of the cost and level of reduction of such pollutants from the discharge from
POTWs to the cost and level of reduction of such pollutants from a class or category of industrial sources.
EPA explained its methodology for developing BCT limitations in detail in 51 FR 24974. July 9. 1986
. See CWA sections 301(b)(2)(E) and 304(b)(4).
Best Available Technology Economically Achievable (BAT)
For the direct discharge of toxic and non-conventional pollutants, EPA promulgates effluent guidelines
based on BAT. The FWPCA amendments of 1972 require EPA to consider the cost of achieving effluent
reductions when defining BAT; however, they do not specifically require EPA to balance the cost of
implementation against the pollution reduction benefit. The technology selected for BAT must be
economically achievable [CWA section 301(b)(2)(A)]. EPA generally defines BAT on the basis of the
performance associated with the best control and treatment measures that facilities in an industrial
category are capable of achieving. Like BPT and BCT, other factors EPA must consider in assessing BAT
include the age of equipment and facilities involved, the process employed, process changes, non-water
quality environmental impacts, including energy requirements, and other such factors as the EPA
Administrator deems appropriate [CWA section 304(b)(2)(B)]. The Agency retains considerable
discretion in assigning the weight accorded to these factors. BAT limitations may be based on effluent
reductions attainable through changes in a facility's processes and operations. Where existing
performance is uniformly inadequate, BAT may reflect a higher level of performance than is currently
being achieved within a subcategory on the basis of technology transferred from a different subcategory
or category. BAT may be based on process changes or internal controls, even when those technologies are
not common industry practice. See CWA sections 301(b)(2)(A), (C), (D) and (F) and 304(b)(2).
New Source Performance Standards (NSPS)
NSPS reflect effluent reductions that are achievable by direct dischargers based on the best available
demonstrated control technology. New sources have the opportunity to install the best and most efficient
production processes and wastewater treatment technologies at the time of construction. As a result,
NSPS should represent the most stringent controls attainable through the application of the best available
demonstrated control technology for all pollutants (i.e., conventional, nonconventional, and toxic
pollutants). In establishing NSPS, EPA is directed to take into consideration the cost of achieving the
effluent reduction and any non-water quality environmental impacts and energy requirements. See CWA
section 306.
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Pretreatment Standards for Existing Sources (PSES)
PSES are designed to prevent the discharge of pollutants that pass through, interfere with, or are
otherwise incompatible with the operation of POTWs, including incompatibility with the POTW's chosen
biosolids (sewage sludge) disposal methods. The categorical pretreatment standards for existing indirect
dischargers are technology-based and are analogous to BAT. The general pretreatment regulations, which
set forth the framework for the implementation of national pretreatment standards, are at Part 403. See
CWA section 307(b).
Pretreatment Standards for New Sources (PSNS)
Like PSES, PSNS are designed to prevent the discharges of pollutants that pass through, interfere with, or
are otherwise incompatible with the operation of POTWs. PSNS are to be issued at the same time as
NSPS. New indirect dischargers have the opportunity to incorporate into their facilities the best available
demonstrated technologies at the time of construction. The Agency considers the same factors in
promulgating PSNS as it considers in promulgating NSPS. See CWA section 307(c).
EPA typically does not establish pretreatment standards for conventional pollutants (e.g., BOD5, TSS, oil
and grease) because POTWs are designed to treat such pollutants, but EPA has exercised its authority to
establish categorical pretreatment standards for conventional pollutants as surrogates for toxic or
nonconventional pollutants or to prevent interference. For example, EPA established categorical
pretreatment standards for new and existing sources with a one-day maximum concentration of 100 mg/L
oil and grease in the Petroleum Refining Point Source Category in Part 419 based on "the necessity to
minimize [the] possibility of slug loadings of oil and grease being discharged to POTWs."3
The final statutory deadline for meeting BPT requirements was July 1, 1977, and the final statutory
deadline for meeting BCT and BAT requirements was March 31, 1989. When applying applicable
effluent guidelines, permit writers should note that they do not have the authority to extend the statutory
deadlines in an NPDES permit; thus, all applicable technology-based requirements (i.e., effluent
guidelines and case-by-case limitations based on BPJ) must be applied in NPDES permits without the
benefit of a compliance schedule. In addition, though NSPS do not have specific dates as compliance
deadlines, they are effective on the date the new source begins discharging. The facility must demonstrate
compliance with NSPS within 90 days of discharge [see § 122.29(d)]. For more information on
determining whether a discharge is subject to NSPS, see Appendix D of this manual. For additional
information on the statutory and regulatory history of the NPDES program, see section 1.2 of this manual.
5.2.1.2 EPA's Development of Effluent Guidelines
EPA establishes national effluent guidelines for a specific industrial sector by regulation after considering
an in-depth engineering and economic analysis of the industrial sector. EPA's Industrial Regulations
Website provides development documents for some specific industry
categories (e.g., Iron and Steel Manufacturing and Metal Products and Machinery). Those documents
contain additional information on how EPA develops effluent guidelines.
For each industrial sector, EPA assesses the performance and availability of the best pollution control
technologies and pollution prevention practices that are available for an industrial category or
subcategory. The effluent guidelines are promulgated for various industrial categories in 40 CFR, Chapter
I, Subchapter N - Effluent Guidelines and Standards - Parts 400-471 .
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In promulgating effluent guidelines, EPA may divide an industrial point source category into groupings of
subcategories to provide a method for addressing variations between products, raw materials, processes,
and other factors that result in distinctly different characteristics. Regulation of an industrial category
using subcategories allows each subcategory to have a uniform set of requirements that take into account
technological achievability and economic impacts unique to that subcategory. Grouping similar facilities
into subcategories increases the likelihood that the regulations are practicable and diminishes the need to
address variations between facilities within a category through a variance process. For more on variances,
see section 5.2.2.7 below. EPA considers a number of different subcategorization factors during an
effluent guidelines rulemaking, including the following:
Manufacturing products and processes.
Raw materials.
Wastewater characteristics.
Facility size.
Geographical location.
Age of facility and equipment.
Wastewater treatability.
For each possible treatment technology option for an industry, EPA conducts an analysis of industry-wide
incremental compliance costs, pollutant loadings and removals, and related non-water quality effects. The
Agency also performs an economic analysis to assess the financial impact on the industry of
implementing each option. That entire process involves data collection, rigorous data review, engineering
analysis, and public comment. EPA selects a technology to serve as the model technology for pollutant
removal for each required level of control (i.e., BPT, BCT, BAT, NSPS, PSES, and PSNS). Limitations
and other requirements in the effluent guidelines for each level of control are based on application of the
model technology to the category or subcategory of facilities.
Effluent guidelines are not always established for every pollutant present in a point source discharge. In
many instances, EPA promulgates effluent guidelines for an indicator pollutant. Industrial facilities that
comply with the effluent guidelines for the indicator pollutant will also control other pollutants (e.g.,
pollutants with a similar chemical structure). For example, EPA may choose to regulate only one of
several metals present in the effluent from an industrial category, and compliance with the effluent
guidelines will ensure that similar metals present in the discharge are adequately controlled. Additionally,
for each industry sector EPA typically considers whether a pollutant is present in the process wastewater
at treatable concentrations and whether the model technology for effluent guidelines effectively treats the
pollutant. For example, see Figure 6-1 Pollutant of Concern Methodology
on page 6-4 of the Centralized Waste Treatment category
Technical Development Document.
The CWA requires EPA to annually review existing effluent guidelines for both direct and indirect
dischargers. CWA section 304(m) also requires EPA to publish an effluent guidelines program plan every
2 years. As part of the development of the biennial plan, the public is provided an opportunity to comment
on a.preliminary plan before it is finalized. The preliminary plan is published in odd-numbered years, and
the final plan is published in even-numbered years. EPA encourages permit writers to participate in the
effluent guidelines planning process and comment on the preliminary effluent guidelines program plans
presented on the Effluent Guidelines Biennial Plan Website .
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5.2.1.3 Types of Limitations in Effluent Guidelines
Although the requirements in effluent guidelines generally are numeric limitations on the mass or
concentration of a pollutant that can be discharged directly into waters of the United States, CWA section
502(11) defines effluent limitation broadly. This section describes several types of possible expressions
for the limitations found in effluent guidelines. The permit writer should note that the limitations in
effluent guidelines might need to be translated into an appropriate form to be included as effluent
limitations in an NPDES permit. That process is discussed further in section 5.2.2 below.
Mass- or Concentration-based Numeric Limitations
Limitations in effluent guidelines generally are expressed as numeric values, which are upper bounds of
the amount of pollutant that may be discharged. For most pollutants, these limitations are mass-based or
concentration-based values. They are, in effect, measures of how well the production, wastewater
treatment, and pollution prevention processes must be operated. In the course of developing effluent
guidelines regulations, EPA uses data on a number of different pollutants from facilities with the selected
model technologies to determine the appropriate numeric limitations. The limitations generally consist of
upper bounds (maximum values) established for both the daily discharge and for the average monthly
discharge.
In developing numeric limitations in effluent guidelines, EPA first determines an average performance
level (the long-term average) that a facility with well-designed and operated model technologies
reflecting the appropriate level of control is capable of achieving. That long-term average is calculated
from data taken from facilities using the model technologies that were selected as a basis for the
limitations. EPA expects that all facilities subject to the limitations will design and operate their treatment
systems to achieve the long-term average performance level consistently because facilities with well-
designed and operated model technologies have demonstrated that it can be done. The technical
development document for the effluent guidelines usually identifies the long-term average for the model
technologies; however, they generally are not part of the limitations in the effluent guidelines or TBELs
in the permit. The limitations generally are expressed as maximum daily and average monthly limitations
(see definitions in Exhibit A-2 in Appendix A of this document) that include an allowance for variability
around the long-term average.
EPA acknowledges that process and treatment systems have inherent variability and, therefore,
incorporates an allowance for this variation into the limitations specified in the effluent guidelines. That
allowance is based on statistical analysis of the data from facilities using the model technologies. The
limitations included in effluent guidelines incorporate all components of variability including shipping,
sampling, storage, and analytical variability. By accounting for those reasonable excursions above the
long-term average, the limitations in effluent guidelines generally are well above the actual long-term
averages. If a facility operates its treatment system to meet the long-term average, EPA expects the
facility will be able to meet the limitations specified in the effluent guidelines based on that long-term
average.
EPA has different objectives in establishing maximum daily and average monthly limitations in effluent
guidelines. In establishing maximum daily limitations, EPA's objective is to restrict the discharges on a
daily basis at a level that is achievable for a facility that targets its treatment at the long-term average. In
establishing average monthly limitations, EPA's objective is to provide an additional restriction to help
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ensure that facilities target their average discharges in a manner that will achieve the long-term average.
The average monthly limitation requires continuous dischargers to provide ongoing control on a monthly
basis that complements controls imposed by the maximum daily limitation. To meet the average monthly
limitation, a facility must counterbalance a value near the maximum daily limitation with one or more
values well below the maximum daily limitation. To achieve compliance, the values must result in an
average monthly value at or below the average monthly limitation. As explained below, EPA uses a
smaller percentile basis for the average monthly limitation than the maximum daily limitation to
encourage facilities to target their systems to a value closer to the long-term average.
EPA generally uses statistical procedures to determine the values of the limitations specified in the
effluent guidelines. Those procedures involve fitting effluent data to distributions and using estimated
upper percentiles of the distributions. EPA defines the maximum daily limitation as an estimate of the
99th percentile of the distribution of the daily measurements. The average monthly limitation is an
estimate of the 95th percentile of the distribution of the monthly averages of the daily measurements.
EPA bases its limitations on percentiles chosen with the intention that they be high enough above the
long-term average to accommodate reasonably anticipated variability within control of the facility. In
conjunction with the statistical methods, EPA performs an engineering review to verify that the
limitations are reasonable on the basis of the design and expected operation of the control technologies
and the facility process conditions. Such limitations are translated into effluent limitations in a facility's
NPDES permit. Facilities must comply with the effluent limitations in their permits at all times. EPA has
prevailed in several judicial challenges to its selection of percentiles and on other issues related to
limitations specified in effluent guidelines. [See, for example, Chemical Manufacturers Association v.
U.S. Environmental Protection Agency. 870 F.2d 177, 230 (5th Cir. 1989) and National Wildlife
Federation, et al v. Environmental Protection Agency, 286 F.3d 554 (B.C. Cir. 2002)]
Exhibit 5-9 depicts an example of TSS data for a facility that is operating around a required long-term
average level for TSS. The dots represent daily measurements, and the reference lines show the values for
the long-term average (LTA), the maximum daily limitation (LI), and the average monthly limitation
(L30). The facility has demonstrated compliance with both the maximum daily and average monthly
limitations. Daily measurements include values both above and below the long-term average; however, all
the data values are below the maximum daily limitation. Some individual daily values exceed the average
monthly limitation; however, within each month, the average of the daily values is less than the average
monthly limitation.
EPA generally exercises four basic alternatives in setting mass- or concentration-based numeric
limitations specified in effluent guidelines:
Mass-based, production-normalized limitations (e.g., the pollutant discharge is not to exceed
1 pound per 1,000 pounds of production).
Mass-based, flow-normalized limitations (e.g., the pollutant discharge is not to exceed the mass
determined by multiplying the process wastewater flow subject to the effluent guideline by the
concentration requirement in the guideline).
Concentration-based limitations (e.g., the pollutant discharge is not to exceed 1 mg of pollutant
per liter of wastewater).
Limitations requiring zero discharge of specific pollutants or all pollutants.
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Exhibit 5-9 Visual example of TSS LTA, maximum daily limitation and average monthly
limitation
10-
8-
6-
4-
2-
0-
L1
L30
LTA
days
LTA = Long-term average
L1 = Daily maximum effluent limitation
L30 = Monthly average effluent limitation
Except where a limitation requiring zero discharge of pollutants is applicable, EPA generally prefers
setting production-normalized, mass-based limitations specified in effluent guidelines, where feasible,
because production normalized limitations can reflect some expectation that the facility will conserve
water and can reduce any potential for substituting dilution for treatment. EPA generally establishes
concentration-based effluent guidelines when production and achievable wastewater flow cannot be
correlated nationally. For example, in the Metal Finishing point source Category (Part 433), the Agency
considered but decided against expressing the effluent guidelines as production-normalized mass-based
effluent guidelines, "With the wide range of operations, product quality requirements, existing process
configurations, and difficulties in measuring production, no consistent production normalizing
relationship could be found. Concentration-based limits, however, can be consistently attained throughout
the industry." [See 47 FR 38465, 31 August 1982.]
Numeric Limitations Established at Minimum Levels
Using percentile estimates to set limitations in effluent guidelines is not a requirement under the CWA. In
some cases, the model technology for treating a pollutant might be capable of removing that pollutant to
levels that cannot be reliably measured with existing analytical methods. EPA sometimes sets a
requirement in the effluent guidelines that the concentration of a pollutant in the discharge must be below
a minimum level or ML. The ML is the lowest level at which the entire analytical system must give a
recognizable signal and an acceptable calibration point for the pollutant being analyzed. Where a
limitation in the effluent guidelines is set at less than the ML, the value of the ML is specified in the
effluent guidelines regulation on the basis of the analytical methods that EPA used to chemically analyze
wastewaters in developing the regulation. For example, in the Pulp, Paper, and Paperboard point source
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category (Part 430) the Daily Maximum BAT effluent guideline for the Tetrachlorodibenzofuran (TCDF)
congener of dioxin is expressed as
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Permit writers need to have a detailed knowledge of the industrial facility applying for a new or reissued
NPDES permit to identify applicable effluent guidelines and know how to use them to derive TBELs.
This section provides a step-by-step procedure for applying effluent guidelines to direct discharges
through NPDES permits as shown in Exhibit 5-10.
Exhibit 5-10 Steps for applying effluent guidelines to direct discharges
Step 1. Learn about the industrial discharger
Step 2. Identify the applicable effluent guidelines category(ies)
Step 3. Identify the applicable effluent guidelines subcategory(ies)
Step 4. Determine whether existing or new source standards apply
Step 5. Calculate TBELs from the effluent guidelines
Step 6. Account for overlapping or multiple effluent guidelines requirements
Step 7. Apply additional regulatory considerations in calculating TBELs
Step 8. Apply additional effluent guidelines requirements
Step 9. Document the application of effluent guidelines in the fact sheet
5,2,2,1 1: About the Industrial Discharger
To write a defensible permit, the permit writer should have a solid understanding of the facility's
operations. The permit writer should gather sufficient information to identify applicable effluent
guidelines and derive TBELs. Facility-specific information the permit writer is likely to need includes the
following:
Industrial processes and raw materials.
Products and services.
Amount of manufacturing production or servicing.
Number of production and non-production days.
Current pollution prevention practices and wastewater treatment technology(ies).
Discharge location of the wastewater pollutants and potential compliance sampling points.
The source and characteristics of the wastewaters (including flow) and pollutants that are being
discharged or have the potential to be discharged from the facility.
Sources of information include the facility's permit application, the current permit and fact sheet (if the
facility is permitted), discharge monitoring reports, site visits, site inspections (such as compliance
evaluation inspections for an existing permit), and other information submitted by the facility. The permit
writer also should identify any information that would assist in determining whether the facility or part of
the facility is considered a new source (e.g., age of facility and equipment).
5,2,2,2 2: the Category(ies)
As noted above, EPA's effluent guidelines are at 40 CFR. Chapter I. Subchapter N - Effluent Guidelines
and Standards. Parts 400-471 . A summary of promulgated effluent
guidelines is presented on EPA's Industrial Regulations Website and in
Exhibit 5-11 below.
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Exhibit 5-11 Table of existing point source categories (June 2010)
Industry category
(listed alphabetically)
40 CFR Industry category
Part (listed alphabetically)
40 CFR
Part
Aluminum Forming
Asbestos Manufacturing
Battery Manufacturing
Canned and Preserved Fruits and Vegetable
Processing
Canned and Preserved Seafood Processing
Carbon Black Manufacturing
Cement Manufacturing
Centralized Waste Treatment
Coal Mining
Coil Coating
Concentrated Animal Feeding Operations
(CAFOs)
Concentrated Aquatic Animal Production
Copper Forming
Dairy Products Processing
Electrical and Electronic Components
Electroplating*
Explosives Manufacturing
Ferroalloy Manufacturing
Fertilizer Manufacturing
Glass Manufacturing
Grain Mills
Gum and Wood Chemicals
Hospitals
Ink Formulating
Inorganic Chemicals
Iron and Steel Manufacturing
Landfills
Leather Tanning and Finishing
* This category contains only categorical pretreatme
467
427
461
407
408
458
411
437
434
465
412
451
468
405
469
413
457
424
418
426
406
454
460
447
415
420
445
425
nt standards
Meat and Poultry Products
Metal Finishing
Metal Molding and Casting
Metal Products and Machinery
Mineral Mining and Processing
Nonferrous Metals Forming and Metal
Powders
Nonferrous Metals Manufacturing
Oil and Gas Extraction
Ore Mining and Dressing
Organic Chemicals, Plastics, and Synthetic
Fibers
Paint Formulating
Paving and Roofing Materials (Tars and
Asphalt)
Pesticide Chemicals
Petroleum Refining
Pharmaceutical Manufacturing
Phosphate Manufacturing
Photographic
Plastic Molding and Forming
Porcelain Enameling
Pulp, Paper, and Paperboard
Rubber Manufacturing
Soaps and Detergents Manufacturing
Steam Electric Power Generating
Sugar Processing
Textile Mills
Timber Products Processing
Transportation Equipment Cleaning
Waste Combustors
(no effluent guidelines for direct dischargers).
432
433
464
438
436
471
421
435
440 |
414 |
446 \
443 |
455 |
419
439
422
459
463
466
430
428
417
423
409
410
429
442 |
444 |
The following sources of information might be helpful in identifying applicable effluent guidelines for a
facility:
CFR titles and applicability section of the effluent guidelines. This is first place to look for
information for identifying applicable effluent guidelines. Each effluent guidelines regulation
includes an applicability section for the category or each subcategory of the industry. The
applicability section gives a general description of the types of facilities regulated by the effluent
guidelines. The applicability sections often define certain industrial operations or other criteria
(e.g., production or process wastewater flow thresholds) that identify whether a facility is
regulated by the effluent guidelines.
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North American Industry Classification System (NAICS) and Standard Industrial
Classification (SIC). The current NAICS and former SIC
codes could be helpful to determine the appropriate
industrial category(ies) for a facility. NAICS and SIC codes were developed and are maintained
by the federal government as a way to classify establishments by type of activity for comparing
economic and other types of facility-specific data. Although SIC codes provide a helpful starting
point for categorizing a facility, permit writers should be cautious of relying exclusively on SIC
codes for determining the appropriate industrial category. SIC codes were not developed using
EPA's industrial classification scheme, or vice versa, and, therefore, the codes might not always
correspond exactly with the categorization process. In addition, more than one SIC code might
apply to a single facility. Item V-II of NPDES Application Form 1 requires that the applicant
provide the SIC code for the activity covered by the permit application. In some instances, the
SIC code will identify both the industrial category and the subcategory of a facility. Sometimes
the SIC code might identify the appropriate industrial category but not the subcategory. Exhibit
5-12 presents two examples of how a permit writer might identify the applicable effluent
guidelines using the facilities SIC codes.
Exhibit 5-12 Examples of identifying applicable effluent guidelines using SIC codes
Example 1 j
A facility that performs the primary smelting and refining of copper reports SIC code 3331 in its NPDES
permit application. By scanning the list of industrial point source categories, the permit writer can
determine that the facility is regulated by effluent guidelines in the Nonferrous Metals Manufacturing point
source category (Part 421). In this case, the SIC code also indicates that the facility is likely regulated by
effluent guidelines in the Primary Copper Smelting Subcategory.
Example 2
A facility that manufactures ethyl acrylate and 2-ethylhexyl acrylate (acrylic acid esters) reports the SIC
code 2869 (Industrial Organic Chemicals, Not Elsewhere Classified) in its NPDES permit application. By
scanning the list of industrial point source categories, the permit writer can determine that facility is likely
regulated by effluent guidelines in the Organic Chemicals, Plastics, and Synthetic Fibers (OCPSF)
category (Part 414).
EPA's Development Documents and Compliance Guides. EPA produces a number of
documents that will aid permit writers in identifying applicable effluent guidelines and
incorporating them into NPDES permits. In particular, development documents summarize the
data and information EPA used to develop the effluent guidelines. Such documents are extremely
useful in identifying the applicability of the effluent guidelines and how to incorporate the
effluent guidelines into NPDES permits. EPA may also publish a compliance guide for permit
writers and industry. EPA's Effluent Guidelines Website provides available
documents for specific industrial categories.
FR Notices. The preamble text to the FR notices containing the proposed and final effluent
guidelines rulemakings also provide additional insight into applicability of the effluent guidelines.
EPA's Effluent Guidelines Website provides FR notices for specific
industrial categories. For example, the preambles to recently promulgated effluent guidelines
typically list the SIC and NAICS codes for the potentially regulated facilities. Each Part in the
CFR identifies the relevant FR notices. For example, §419.11 (i.e., specialized definitions for
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Subpart [subcategory] A for the Petroleum Refining point source category) identifies 47 FR
46446, October 18, 1982, as amended at 50 FR 28522, July 12, 1985, as its source.
EPA Industry Experts. EPA has a number of subject matter experts
at its headquarters office in Washington, B.C. that are available to
answer questions on specific effluent guidelines. EPA's NPDES Contacts in Regional Offices
also offer assistance in sorting through the different effluent
guidelines and NPDES regulations.
EPA's Effluent Guidelines Planning Support Documents. EPA's Effluent Guidelines Biennial
Plan Website provides technical support
documents and other information supporting EPA's biennial effluent guidelines program plans.
EPA's Sector Notebooks. EPA's Sector Notebooks
describe specific
U.S. industries and governments and provide a holistic approach by integrating processes,
applicable regulations, and other relevant environment information.
Other Sources. Other sources of information include resources identified below in Exhibit 5-23,
BPJ Permitting Tools. Permit and fact sheet and information from similar facilities might aid in
identifying applicable effluent guidelines. However, the permit writer should not assume that a
similar facility was correctly categorized in its permit and should examine the rationale for how
the other permit writer identified any applicable effluent guidelines before relying on another
permit to identify the applicable category.
Permit writers should be aware that effluent guidelines from two or more industrial point source
categories might apply to a single facility. Step 6 below, provides additional information on overlapping
or multiple effluent guidelines requirements.
5.2.2.3 Step 3: Identify the Applicable Effluent Guidelines Subcategory(ies)
In promulgating effluent guidelines, EPA may divide an industrial point source category into groupings
called subcategories to provide a method for addressing variations between products, raw materials,
processes, and other factors that result in distinctly different effluent characteristics or treatment options.
Some effluent guidelines categories cover a variety of industrial sectors (e.g., the Nonferrous Metals
Manufacturing point source category has 31 subcategories). It is important for the permit writer to
correctly identify the applicable subcategory to derive TBELs.
The process of identifying the applicable effluent guidelines requires close review and comparison of
information obtained from Step 1 and Step 2 above. Just as effluent guidelines from two or more
industrial categories can apply to a single facility, it also is true that requirements from two or more
subcategories could apply to a single facility.
Exhibit 5-13 presents two examples of how a permit writer can identify the subcategory containing the
applicable effluent guidelines using information from the NPDES permit application.
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Exhibit 5-13 Examples of identifying the subcategory with the applicable effluent guidelines
; Example 1
| A permit writer has identified the facility from Example 2 in Exhibit 5-12 above as potentially regulated by the
j effluent guidelines in the OCPSF point source category (Part 414) . The permit writer
I can determine from a further review of the industrial categorization discussion in the OCPSF Development
| Document and the guidance document that the facility is likely subject to effluent guidelines in Subpart G (Bulk
I Organic Chemicals). Specifically, the applicability criteria section in Subpart G (§ 414.70) states, "The provisions of
j this subpart are applicable to the process wastewater discharges resulting from the manufacture of the following:
| SIC 2865 and 2869 bulk organic chemicals and bulk organic chemical groups." Further, acrylic acid esters are
| listed in § 414.70 as an OCPSF product group.
( Example 2
j A large poultry slaughterhouse annually produces 200 million pounds of whole, halved, quarter or smaller meat
j cuts and reports SIC Code 2015 in its NPDES permit application. The permit writer reviewed the list of effluent
J guidelines and identified that the facility is likely regulated by effluent guidelines in the Meat and Poultry Products
I point source category (Part 432) . The permit writer reviewed the preamble to the final
| effluent guidelines rule and the rule's development document. In that effluent guidelines regulation, EPA used
| NAICS codes to assist in applicability decisions. See 69 FR 54475, September 8, 2004. The permit writer used the
1 U.S. Census Bureau's SIC to NAICS crosswalk website to identify the
| NAICS code (311615). Using the NAICS code, the permit writer can narrow the list of potentially applicable
I subcategories to the Poultry First Processing (Subpart K) or the Poultry Further Processing (Subpart L)
| subcategories. After reviewing the applicability criteria of both subcategories, the permit writer determined that only
I the effluent guidelines in Subpart K are likely applicable because the facility performs slaughtering operations,
1 which are not regulated by Subpart L. Finally, the permit writer also needed to compare the average annual
j production of the facility (200 million pounds) with the production threshold in the effluent guidelines (100 million
j pounds per year). Because the facility produces more than the production threshold, the effluent guidelines in
j Subpart Kare applicable to this facility. See §§ 432.112 and 432.113. In this example the permit writer would use
| the effluent guidelines for ammonia (as N), BODs, fecal coliform, oil and grease (as HEM), TSS, and total nitrogen
I to derive effluent limitations as detailed in section 5.2.2.5 below.
5.2.2.4 4; or
Section 5.2.1.1 above defines the different control technologies that apply to direct dischargers: BPT,
BCT, BAT, and NSPS. The first three apply to existing direct dischargers, and the fourth to new sources.
To determine whether existing source standards (i.e., BPT, BCT, and BAT) or NSPS apply to the facility,
the permit writer must determine whether the facility or any part of the facility is a new source. A new
source is defined in § 122.2 as a building, structure, facility, or installation that discharges pollutants or
could discharge pollutants and for which construction began after promulgation of the applicable effluent
guidelines or after proposal of the applicable effluent guidelines, but only if the effluent guidelines are
promulgated within 120 days. Thus, the discharger's entire facility could be subject to new source
standards (e.g., a brand new facility). Permit writers should note that the new source date for indirect
dischargers is the date on which the pretreatment standard for new sources is proposed. See §403.3(m)(l).
Additional criteria for determining whether a discharge is a new source are defined in § 122.29(b) to
cover situations where a facility is adding a new building or process line that results in a discharge to the
waters of the United States. Such an addition would result in a new source if any of the following is true
for the source:
Is constructed at a site at which no other source is located.
Totally replaces the process causing the discharge from an existing source.
Has processes that are substantially independent of an existing source at the same site.
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Furthermore, some effluent guidelines, such as the effluent guidelines for the Pulp, Paper, and Paperboard
Point Source Category in Part 430, include additional criteria for making new source determinations. See
§430.01(j).
Appendix D of this manual provides the applicable new source dates used in making new source
determinations by effluent guideline category as provided in Appendix B of the EPA memorandum New
Source Dates for Direct and Indirect Dischargers4 < www.epa. gov/npdes/pubs/newsource dates.pdf> sent by the
directors of the Water Permits Division and the Engineering and Analysis Division to the Regional Water
Division Directors. Permit writers can use Appendix D of this manual to find the date for determining
whether a facility or part of a facility is subject to NSPS.
Where a new source is the result of a new installation of process equipment at an existing facility, part of
the facility might be subject to existing source standards and other parts of the facility subject to new
source standards. Permit writers should identify whether the facility has installed any process equipment
after the last issuance of the NPDES permit and apply the criteria from § 122.29(b) on a case-by-case
basis to new construction or new processes, while applying existing source requirements to the existing
portions of the facility. Sometimes it can be difficult to distinguish between a new source and a
modification or alteration of an existing source, especially when modifications have occurred slowly over
time. The permit writer should consult the effluent guidelines regulation to determine if it defines more
specifically what constitutes a new source.
It is important to remember that after the effective date of anew source standard, the CWA stipulates that
it is unlawful for any owner or operator to operate such a source in violation of those standards. See
33 U.S.C. 1316(e) and 1317(d). EPA's regulations specify that a new source "[must] install and have in
operating condition, and [must] start up all pollution control equipment" required to meet applicable
standards before beginning to discharge. The regulations also indicate that the owner or operator of a new
source must meet all applicable standards within "the shortest feasible time (not to exceed 90 days)." See
§ 122.29(d)(4).
In addition to the requirement to meet NSPS upon beginning to discharge, an EPA-issued NPDES permit
for a new source is a federal action subject to the requirements of the National Environmental Policy Act
(NEPA), 33 U.S.C. 1371(c)(l). For more information on NEPA and the NPDES program, see section
11.1.2 of this manual.
For existing facilities and existing sources (where NSPS do not apply), existing source standards (i.e.,
BPT, BCT, BAT) apply. The permit writer would use the more stringent technology level of control for
each pollutant. For example, the BPT level of control in the Veneer Subcategory of the Timber Products
Processing category (Part 429, Subpart B) allows a discharge of process wastewater and identifies
effluent guidelines for BOD5 and pH, while the BAT level of control bans the direct discharge of process
wastewater. Consequently, the NPDES permit for a facility regulated by the Veneer Subcategory must use
the more stringent BAT requirements and prohibit the direct discharge of process wastewater. The
effluent guidelines for the Renderers Subcategory of the Meat and Poultry Products point source category
(Subpart J, Part 432) provide another example. In those effluent guidelines, the BCT requirements for
BOD5, oil and grease, and TSS are more stringent than the corresponding BPT requirements.
Accordingly, the permit writer would use the more stringent BCT requirements, rather than the BPT
requirements, to derive numeric permit limitations for an existing Tenderer.
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5.2.2.5 Step 5: Calculate TBELs from the Effluent Guidelines
Once a permit writer has identified the effluent guidelines that apply to a facility, he or she then uses
those effluent guidelines to calculate applicable TBELs.
EPA's regulations at § 122.45(f)(l) stipulate that all pollutants limited in permits must have limitations,
standards or prohibitions expressed in terms of mass except under any of the following conditions:
For pH, temperature, radiation, or other pollutants that cannot appropriately be expressed by mass
limitations.
When applicable standards or limitations are expressed in terms of other units of measure.
If in establishing technology-based permit limitations on a case-by-case basis, limitations based
on mass are infeasible because the mass or pollutant cannot be related to a measure of production
(e.g., discharges of TSS from certain mining operations). The permit conditions must ensure that
dilution will not be used as a substitute for treatment.
Thus, the type of limitation (i.e., mass, concentration, or other units) calculated for a specific pollutant at
a facility will depend on the type of pollutant and the way limitations are expressed in the applicable
effluent guideline. Generally, effluent guidelines include both maximum daily and monthly average
limitations for most pollutants. Though the effluent guidelines use different terms for monthly effluent
limitations (e.g., monthly average, maximum for monthly average, average of daily values for 30
consecutive days), the requirements are expressed in NPDES permits as average monthly limitations as
defined in § 122.2.
As stated in Steps 1 and 2 above, the permit writer would use many sources of information to calculate
TBELs. From those sources, the permit writer should identify the source and characteristics of the
wastewaters (including flow) and pollutants being discharged, or that have the potential to be discharged,
and whether and how those pollutants are regulated by effluent guidelines. In particular, the permit writer
should identify the following:
The appropriate permit compliance point(s) (which might be specified in the effluent guidelines).
Wastewaters subject to the applicable effluent guidelines and whether they are commingled with
other wastewaters not regulated by effluent guidelines (e.g., sanitary wastewaters before the
permit compliance point).
Reasonable measure of the facility's actual long-term daily production and average number of
production days per year regulated by effluent guidelines (necessary for derived effluent
limitations from production-normalized effluent guidelines).
Average daily facility flows at the compliance point(s) regulated by effluent guidelines.
Average daily facility flows at the compliance point(s) not regulated by effluent guidelines.
That information is used in conjunction with the effluent guidelines for TBEL calculations as discussed
below.
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Calculating Mass-based TBELs from Production-Normalized Effluent Guidelines
Most effluent guidelines requirements are mass-based and expressed in terms of allowable pollutant
discharge per unit of production or some other measure of production (i.e., production normalized).
Permit writers incorporate such production-normalized effluent guidelines into NPDES permits as mass-
based TBELs by using a reasonable measure of the permittee's actual long-term daily production. The
objective in determining the production for a facility is to develop a single estimate of the long-term
average daily production that can reasonably be expected to prevail during the next term of the permit
(i.e., not the design production rate). Permit writers may establish such a production rate using the past 3
to 5 years of facility data. For example, the permit writer might wish to use the average daily production
rate calculated using the highest annual production from the previous 3 to 5 years. Whatever value is
selected, the permit writer should ensure that the production rate used in deriving mass-based effluent
limitations is representative of the actual production likely to prevail during the next term of the permit.
The examples in Exhibit 5-14 illustrate the application of production-based effluent guidelines using the
approach where annual production data are available. In Example 1 in Exhibit 5-14, the highest annual
production rate during the past 5 years was used as the estimate of production. If historical trends, market
forces, company plans to decrease production, or plant designs and capital expenditures for an increase in
production indicated that a different level of production would prevail during the permit term, the permit
writer could consider a different basis for estimating production or establish tiered discharge limitations,
as discussed in section 5.2.2.7 below.
Calculating Mass-based TBELs from Flow-Normalized Effluent Guidelines
In some cases, permit writers are directed to calculate mass-based TBELs from flow-normalized effluent
guidelines that are expressed as concentrations. For example, the Organic Chemicals. Plastics, and
Synthetic Fibers (OCPSF) effluent guidelines in Part 414 state that
facilities "must achieve discharges not exceeding the quantity (mass) determined by multiplying the
process wastewater flow subject to [the effluent guideline] times the concentration listed in the [effluent
guideline]..." The Development Document for Effluent Limitations Guidelines and Standards for the
Organic Chemicals, Plastics and Synthetic Fibers Point Source Category5
directs the permit writer to "use a reasonable estimate of
process wastewater discharges and the concentration limitations [in the effluent guideline] to develop
mass limitations for the NPDES permit." Thus, the process for calculating the TBELs is similar to the
process used with production-normalized effluent guidelines, but rather than using a reasonable measure
of the actual daily production, the permit writer would use a reasonable measure of the actual daily flow
rate as the basis for calculating the TBELs.
As with estimating production to calculate TBELs, the objective in determining a flow estimate for a
facility is to develop a single estimate of the actual daily flow rate (in terms of volume of process
wastewater per day), which can reasonably be expected to prevail during the next term of the permit (i.e.,
not the design flow rate). Permit writers can establish that flow rate using the past 3 to 5 years of facility
data in a manner similar to the method used to determine production. For example, the permit writer
might wish to use the highest average daily flow rate from the average daily flows calculated for each of
the past 3 to 5 years. The value selected should be representative of the actual flow likely to prevail
during the next term of the permit.
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Exhibit 5-14 Example of calculating mass-based effluent limitation from production-
normalized effluent guidelines6
Example 1
Facility A has produced 331,000 tons, 301,500 tons, 321,500 tons, 330,000 tons, and 331,500 tons of product per
year for the previous 5 years operating 255 days per year.
Question:
What would be a reasonable measure of production for permitting purposes?
Answer:
Using the highest year of production (331,500 tons per year) might be an appropriate and reasonable measure of
production, if this figure is representative of the actual production expected to occur over the next term of the
permit. Permit writers also should check to see if the maximum yearly value is within a certain percentage
(e.g., 20 percent-see section 5.2.2.7 below) of the average value. In evaluating gross production figures, the
number of production days should be considered. If the number of production days per year is not comparable, the
permit writer would need to convert the numbers to production per day before comparing them. In this example, all
the yearly production figures were based on 255 days per year of production, so they may be compared directly.
The 331,500 tons per year figure is the maximum for the past 5 years, which is only 2.6 percent above the average
annual production of 323,100 tons. Therefore, 331,500 tons is a reasonable measure of the annual production for
the facility.
Example 2
For the same facility in Example 1 above with an annual production of 331,500 tons, the production-normalized
effluent guidelines for zinc are 0.1 lbs/1,000 Ibs as monthly average and 0.15 lbs/1,000 Ibs as daily maximum.
Question:
What are the resulting zinc technology-based effluent limitations for the NPDES permit?
Answer:
The annual production would be converted to an average daily production rate to apply the effluent guidelines. To
convert from the annual production rate to an average daily rate, divide the annual production rate by the number
of production days per year. To determine the number of production days, subtract the total number of normally
scheduled non-production days from the total days in a year. Because Company A normally has 255 production
days per year, the annual production rate of 331,500 tons per year would yield an average production daily rate of
1,300 tons per day.
Monthly average discharge limitation for zinc*:
1,300 tons/day x 2,000 Ibs/ton x 0.10 lbs/1,000 Ibs = 260 Ibs/day
Daily maximum discharge limitation for zinc*:
1,300 tons/day x 2,000 Ibs/ton x 0.15 lbs/1,000 Ibs = 390 Ibs/day
* calculated to 2 significant figures
Calculating TBELs from Concentration-based Effluent Guidelines
Permit writers might want to develop mass-based limitations for facilities with concentration-based
effluent guidelines (e.g., for a facility does not have adequate water conservation practices). Mass-based
permit effluent limitations encourage water conservation (e.g., minimize the potential for diluting process
wastewaters by non-process wastewater, more efficient use of water) and pollution prevention (e.g.,
reduce waste loads to wastewater treatment facilities by physically collecting solid materials before using
water to clean equipment and facilities). Additionally, for facilities with on-site wastewater treatment
systems, the combination of water-reduction technologies and practices and well-operated wastewater
treatment will reduce the volume and mass of discharged wastewater pollution (i.e., after treatment).
Another benefit of mass-based permit effluent limitations is that they provide the permittee with more
flexibility. Permittees may elect to control their wastewater discharges through more efficient wastewater
control technologies and pollution-prevention practices that result in lower pollutant concentrations in the
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discharged wastewater, or more efficient water conservation practices that result in less wastewater
volume discharged from industrial operations), or both.
"EPA strongly supports water conservation and encourages all sectors, including municipal, industrial,
and agricultural, to achieve efficient water use. EPA does not intend for its regulations to present a barrier
to efficient water use in any industrial sector." See final 2006 Effluent Guidelines Program Plan in 71 FR
76655, December 21, 2006.
When calculating mass-based effluent limitations, the permit writer should use a conversion factor and
document in the fact sheet the conversion factors used to calculate the permit limitations (e.g.,
concentration [mg/L] x flow [mgd] x 8.34 [conversion factor] = permit limitation [Ibs/day]).
Additionally, guidance for implementing concentration-based limitations in effluent guidelines may direct
permit writers to develop mass-based TBELs. For example, the Permit Guidance Document
Transportation Equipment Cleaning Point Source Category (40 CFR 442)1 industry states:
The effluent limitations guidelines and standards for the TEC industry are concentration-based and
adhere to the building block concept. Each regulated wastestream in an outfall is typically assigned a
mass-based discharge allowance based on a calculation of its applicable concentration-based
limitation and annual average flow. The sum of the allowances is the total mass discharge allowance
for the outfall. In other words, the applicable permit limitations for facilities in more than one
subcategory is the sum of the mass loadings based upon production in each subcategory and the
respective subcategory effluent limitations guidelines. Mass-based limitations for unregulated or
dilution wastewater streams at direct discharging facilities are established using [BPJ].
Where a permit writer cannot determine a reasonable measure of actual flow for a regulated discharge,
concentration-based TBELs may be determined by directly applying the concentration-based limitations
in effluent guidelines to the regulated flow and accounting for non-regulated flows at the point of
compliance for the TBELs.
Supplementing Mass-based TBELs with Concentration Limitations
Even where effluent guidelines require permit writers to calculate mass-based TBELs, a permit writer
may determine that it is beneficial to include concentration-based limitations to supplement the mass-
based limitations. Where effluent limitations are expressed in terms of mass, a provision at § 122.45(f)(2)
allows the permit writer, at his or her discretion, to express limitations in additional units (e.g.,
concentration units). Where limitations are expressed in more than one unit, the permittee must comply
with both. The permit writer may determine that expressing limitations in terms of both concentration and
mass encourages the proper operation of a treatment facility at all times.
Supplementing mass-based limitations with concentration-based limitations may be especially appropriate
where the requirements in the effluent guidelines are flow-normalized (i.e., the effluent guidelines
includes a concentration requirement but directs the permit writer to calculate a mass-based TBEL using
the concentration requirement and the wastewater flow). The permit writer may determine that if the
permit includes only mass-based limitations derived from the concentration-based limitations in the
effluent guidelines, a permittee could increase its effluent pollutant concentrations above the applicable
concentration requirements during low flow periods (i.e., reduce the efficiency of the wastewater
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treatment) and still meet its mass-based permit limitations. Supplementing the mass-based TBELs with
concentration limitations would discourage the reduction in treatment efficiency during low-flow periods
and require proper operation of treatment units at all times.
Incorporating Narrative Requirements from Effluent Guidelines
The permit writer should also ensure that any applicable narrative effluent guidelines controls or
requirements are included in the permit. For example, the effluent guidelines for Concentrated Aquatic
Animal Production facilities (Part 451) consist of narrative requirements implemented through BMPs.
Another example, related to monitoring and compliance rather than effluent limitations, is found in the
Metal Finishing effluent guidelines. The effluent guidelines allow a facility to make a statement regarding
total toxic organics (TTO) in lieu of monitoring for toxic organics. Exhibit 5-15 provides an example
narrative requirement representing BPT performance standards for Concentrated Aquatic Animal
Production facilities, Subpart A (flow through and recirculating systems) § 455.1 l(a).
Exhibit 5-15 Example narrative requirement from the Concentrated Aquatic Animal
Production effluent guidelineSubpart A [§ 455.11 (a)]
I Except as provided in [§§] 125.30 through 125.32, any existing point source subject to this subpart must meet the
following requirements, expressed as practices (or any modification to these requirements as determined by the
( permitting authority based on its exercise of its best professional judgment) representing the application of BPT:
(a) Solids control. The permittee must:
(1) Employ efficient feed management and feeding strategies that limit feed input to the minimum amount
reasonably necessary to achieve production goals and sustain targeted rates of aquatic animal growth in order to
minimize potential discharges of uneaten feed and waste products to waters of the [United States]
(2) In order to minimize the discharge of accumulated solids from settling ponds and basins and production
systems, identify and implement procedures for routine cleaning of rearing units and off-line settling basins, and
procedures to minimize any discharge of accumulated solids during the inventorying, grading and harvesting
aquatic animals in the production system.
(3) Remove and dispose of aquatic animal mortalities properly on a regular basis to prevent discharge to waters of
the [United States], except in cases where the permitting authority authorizes such discharge in order to benefit j
the aquatic environment. j
5.2.2.6 6: Account for or
There are instances when one facility includes both new and existing sources, produces multiple products
or services, or includes production or services belonging to more than one category or subcategory. In
such cases, the permit writer must examine the applicable effluent guidelines closely to ensure that
(1) one guideline does not supersede another; and (2) the effluent guidelines are properly applied.
Superseding Effluent Guidelines
EPA tries to minimize the overlap of different effluent guidelines by providing exclusions in the
applicability sections. The effluent guidelines in the Metal Finishing point source category (Part 433) are
an example of where EPA has tried to minimize the overlap of multiple effluent guidelines for certain
wastewater discharges. Exhibit 5-16 presents the applicability section in Part 433 [§ 433.10(b)], which
specifically excludes certain wastewaters from the Metal Finishing effluent guidelines. Another example
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is the preamble to the OCPSF effluent guidelines. The preamble identifies numerous circumstances where
the OCPSF regulations are superseded by effluent guidelines for other industrial categories. Exhibit 5-17
presents excerpts from the preamble (52 FR 42523, November 5, 1987) to illustrate the point.
Exhibit 5-16 Exclusion of wastewaters in metal finishing effluent guidelines
;i In some cases, effluent limitations and standards for the following industrial categories might be effective and
:i applicable to wastewater discharges from the metal finishing operations listed above [in paragraph (a)]. In such
: cases these Part 433 limitations shall not apply and the following regulations shall apply: [emphasis added]
Nonferrous metal smelting and refining (40 CFR part 421)
I Coil coating (40 CFR Part 465)
:i Porcelain enameling (40 CFR Part 466)
} Battery manufacturing (40 CFR Part 461)
] Iron and steel (40 CFR Part 420)
:i Metal casting foundries (40 CFR Part 464)
\ Aluminum forming (40 CFR Part 467)
] Copper forming (40 CFR Part 468)
I Plastic molding and forming (40 CFR Part 463)
:i Nonferrous forming (40 CFR Part 471)
; Electrical and electronic components (40 CFR Part 469)
Exhibit 5-17 Excerpts from preamble to OCPSF effluent guidelines regarding applicability of
effluent guidelines
For the purposes of this regulation, OCPSF process wastewater discharges are defined as discharges from all
establishments or portions of establishments that manufacture products or product groups listed in the
applicability sections of this regulation, and are included within the following U.S. Department of Commerce
Bureau of the Census Standard Industrial Classification (SIC) major groups:
- SIC 2865: Cyclic Crudes and Intermediates, Dyes, and Organic Pigments.
- SIC 2869: Industrial Organic Chemicals, not Elsewhere Classified.
- SIC 2821: Plastic Materials, Synthetic Resins, and Nonvulcanizable Elastomers.
- SIC 2823: Cellulosic Man-Made Fibers.
- SIC 2824: Synthetic Organic Fibers, Except Cellulosic.
The OCPSF regulation does not apply to process wastewater discharges from the manufacture of organic
chemical compounds solely by extraction from plant and animal raw materials or by fermentation processes.
The OCPSF regulation does not apply to discharges from OCPSF product/process operations [that] are
covered by the provisions of other categorical industry effluent limitations guidelines and standards if the
wastewater is treated in combination with the non-OCPSF industrial category regulated wastewater. (Different
processes manufacture some products or product groups and some processes with slight operation condition
variations give different products. EPA uses the term product/process to mean different variations of the same
basic process to manufacture different products as well as to manufacture the same product using different
processes.)
The process wastewater discharges by petroleum refineries and pharmaceutical manufacturers from production
of organic chemical products specifically covered by 40 CFR Part 419 Subparts C and E and Part 439 Subpart
C, respectively, that are treated in combination with other petroleum refinery or pharmaceutical manufacturing
wastewater, respectively, are not subject to the OCPSF regulation no matter what SIC code they use to report
their products.
Today's OCPSF category regulation applies to plastics molding and forming processes when plastic resin
manufacturers mold or form crude intermediate plastic material for shipment off-site. The regulation also applies
to the extrusion of fibers. Plastics molding and forming processes, other than those described above are
regulated by the Plastics Molding and Forming effluent guidelines and standards (40 CFR Part 463).
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Exhibit 5-17 Excerpts from preamble to OCPSF effluent guidelines regarding applicability of
effluent guidelines (continued)
Public comments requested guidance relating to the coverage of OCPSF research and development facilities,
standalone OCPSF research and development, pilot plant, technical service, and laboratory bench scale-
operations are not covered by the OCSPF regulation. However, wastewater from such operations conducted in
conjunction with and related to existing OCPSF manufacturing operations at OCPSF facilities is covered by the
OCPSF regulation because these operations would most likely generate wastewater with characteristics similar
to the commercial manufacturing facility. Research and development, pilot plant technical service, and
laboratory operations [that] are unrelated to existing OCPSF plant operations, even though conducted on-site,
are not covered by the OCPSF regulation because they may generate wastewater with characteristic dissimilar
to that from the commercial OCPSF manufacturing facility.
Finally, as described in the following paragraphs, this regulation does not cover certain production that has
historically been reported to the Bureau of Census under a non-OCPSF SIC subgroup heading, even if such
production could be reported under one of the five SIC code groups covered by today's regulation.
Multiple Effluent Guidelines Requirements
NPDES permit writers often find that a facility employs multiple processes each with its own effluent
guidelines requirement. In addition, sometimes effluent guidelines from multiple categories and
subcategories apply to wastewaters for a single facility. When a facility is subject to effluent guidelines
for two or more processes in a subcategory or to effluent guidelines from two or more categories or
subcategories, the permit writer must apply each of the applicable effluent guidelines to derive TBELs. In
applying multiple effluent guidelines, the permit writer should use measures of actual production or flow
that are reasonable with respect to operation of multiple processes at the same time. For example, if
maximum production for one process can occur only when there is reduced production for a second
process, it might not be reasonable to assume maximum production levels for both processes at the same
time when applying the effluent guidelines. If all wastewaters regulated by effluent guidelines are treated
separately but are combined before the discharge, the permit writer may establish internal outfalls and
separately apply the effluent guidelines at the respective internal outfall as discussed in § 122.45(h) and in
Step 7 below.
More commonly, wastewater streams regulated by effluent guidelines are combined during or before
treatment. In such a case, the permit writer combines the allowable pollutant loadings from each set of
requirements or from each set of effluent guidelines to arrive at a single TBEL for the facility using a
building block approach. The building block approach as applied to a facility with multiple processes in
the Primary Tungsten subcategory of the Primary Nonferrous Metals Manufacturing point source
category (Part 421, Subpart J) is presented in Exhibit 5-18. The same principles illustrated in the exhibit
would apply to a facility with processes subject to requirements from multiple subcategories or categories
that are combined before or during treatment.
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Exhibit 5-18 Building block approach for applying effluent guidelines
A facility is subject to Part 421, Subpart J (Primary Tungsten). The facility uses a tungstic acid rinse, an acid leach
wet air pollution control system, and an alkali leach wash in its manufacturing process.
The Maximum daily production rate for the facility is:
4.7 million pounds per day of Tungstic Acid (as W)
3.5 million pounds per day of Sodium Tungstate (as W)
Question:
What is the technology-based effluent limit for lead at the facility?
Answer:
BPT calculation for lead (§ 421.102):
a) Tungstic acid rinse:
(4.7 million Ibs/day) x (17.230 Ibs/million Ibs) = 80.981 Ibs/day
b) Acid leach wet air pollution control:
(4.7 million Ibs/day) x (15.040 Ibs/million Ibs) = 70.688 Ibs/day
c) Alkali leach wash:
(3.5 million Ibs/day) x (0.000 Ibs/million Ibs) = 0.000 Ibs/day
d) Total allowable discharge = 80.981 + 70.688 + 0.000 = 151.669 = 152 Ibs/day
BAT calculation for lead (§ 421.103):
a) Tungstic acid rinse:
(4.7 million Ibs/day) x (11.490 Ibs/million Ibs) = 54.003 Ibs/day
b) Acid leach wet air pollution control:
(4.7 million Ibs/day) x (1.003 Ibs/million Ibs) = 4.7141 Ibs/day
c) Alkali leach wash:
(3.5 million Ibs/day) x (0.000 Ibs/million Ibs) = 0.000 Ibs/day
d) Total allowable discharge = 54.003 + 4.7141 + 0.000 = 58.7171 = 59 Ibs/day*
The technology-based maximum daily limitation for lead at the facility is the BAT limitation of 59 Ibs/day. That
value is compared with the water quality-based effluent limitation for lead, to ensure that all applicable standards
are implemented through the final effluent limitations.
* calculated to 2 significant figures
The building block approach is applied in other circumstances as well, such as
Mixture of mass-based and concentration-based requirements: The limitations in effluent
guidelines for some pollutants are mass-based, production-normalized limitations in some
subparts and concentration-based limitations in other subparts. When all the wastewater streams
go to the same treatment system, the permit writer would need to convert the concentration-based
limitations to mass-based limitations so they could be combined with the mass-based, production-
normalized limitations and applied to the combined wastewater streams.
Mixture of different concentration-based requirements: Some facilities could have multiple
operations that are each subject to different concentration-based requirements for the same
pollutant but with wastewater streams that combine before treatment. In such a case, the permit
writer can establish a flow-weighted concentration-based limitation as the TBEL for the
combined wastewater streams or convert the concentration-based requirements to equivalent
mass-based requirements using flow data and then combine the mass-based requirements into a
single limitation for the combined wastewater streams.
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Mixture of regulated and unregulated wastewater streams: In some cases, wastewater streams
containing a pollutant regulated by the applicable effluent guidelines requirements can combine
with other wastewater streams that do not have effluent guidelines requirements that regulate the
pollutant. In such a case, the permit writer could use BPJ to establish a TBEL for the unregulated
wastewater stream(s) (see section 5.2.3 below) and, as appropriate, calculate a final TBEL for the
combined wastewater streams. For example, if one of the wastewater streams contributing to an
industrial facility's discharge is sanitary wastewater, the permit writer might use BPJ to apply the
treatment standards for domestic wastewater and calculate BOD5 limitations for that wastewater
stream. The secondary treatment standards, discussed in section 5.1 above, could be used to
calculate mass-based limits for the sanitary wastewater using the concentration-based
requirements and an estimate of flow rate that is expected to represent the flow rate during the
proposed permit term. A final TBEL for BOD5 could be calculated for the combined sanitary and
process wastewater streams by combining the two mass limitations using the building block
approach.
Mixture of wastewater streams containing a pollutant with wastewater streams not
containing the pollutant: If a wastewater stream that does not contain a pollutant is combined
with another wastewater stream that contains the pollutant (and has applicable requirements in the
effluent guidelines or requirements determined by the permit writer using BPJ), the permit writer
must ensure that the non-regulated waste stream does not dilute the regulated waste stream to the
point where the pollutant is not analytically detectable. If that occurs, the permit writer will most
likely need to establish internal outfalls, as allowed under § 122.45(h) and in Step 7 below.
For examples of addressing combined wastewater streams, see section 15.3.3 on page 15-10 of EPA's
Technical Development Document for the Final Effluent Limitations Guidelines and Standards for the
Meat and Poultry Products Point Source Category (40 CFR 432)g
.
Facilities with Both New and Existing Sources
Finally, as noted above, if effluent guidelines are applicable to an existing facility, and that facility adds a
new production line, which becomes a new source, the permit writer should calculate TBELs for the
subsequent permit using BPT, BCT, and BAT standards for the existing production line and NSPS for the
new production line, as discussed in section 5.2.2.4 above.
5.2.2.7 Step 7: Apply Additional Regulatory Considerations in Calculating TBELs
The permit writer must consider several additional requirements when deriving TBELs from effluent
guidelines. Those additional requirements consist of evaluating or accounting for the following:
Expected significant increases or decreases in production during the permit term for tiered
discharger limitations.
Internal outfalls.
Requests for a variance from effluent guidelines.
The following sections provide an overview of those topics.
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Tiered Limitations
If production rates are expected to change significantly during the life of the permit, the permit writer can
include tiered (alternate) TBELs as allowed by § 122.45(b)(2)(ii)(A)(i). Tiered TBELs would apply to
mass-based effluent limitations and would become effective when production or flow (or some other
measure of production) exceeded a threshold value, such as during seasonal production variations.
Generally, up to a 20 percent fluctuation in production is considered to be within the range of normal
variability, while changes in production higher than 20 percent could warrant consideration of tiered
limitations. Exhibit 5-19 illustrates application of tiered limitations.
Exhibit 5-19 Example of tiered discharge limitations
Plant B produced approximately 40 tons per day of product during spring and summer months (i.e., March through
August) and 280 tons per day during fall and winter months during the previous 5 years. Production during the fall
and winter months is significantly higher than during the off-season, and the discharger has made a plausible
argument that production is expected to continue at that level. The effluent guidelines requirements for Pollutant Z
are 0.08 lbs/1,000 Ibs for the average monthly limitation and 0.14 lbs/1,000 Ibs for the maximum daily limitation.
Question:
What are appropriate tiered effluent limitations for Plant B?
Answer:
The first tier or lower limitations would be based on a production rate of 40 tons per day. The limitations would
apply between March and August.
Monthly average limitation:
40 tons/day x 2,000 Ibs/ton x 0.08 lbs/1,000 Ibs = 6.4 Ibs/day*
Daily maximum limitation:
40 tons/day x 2,000 Ibs/ton x 0.14 lbs/1,000 Ibs = 11.2 Ibs/day = 11 Ibs/day*
The second tier or higher limitations would be based on a production rate of 280 tons per day. Those limitations
would apply between September and February.
Monthly average limitation:
280 tons/day x 2,000 Ibs/ton x 0.08 lbs/1,000 Ibs = 44.8 Ibs/day = 45 Ibs/day*
Daily maximum limitation
280 tons/day x 2,000 Ibs/ton x 0.14 lbs/1,000 Ibs = 78.4 Ibs/day = 78 Ibs/day*
* calculated to 2 significant figures
Permit writers should include tiered limitations in a permit only after careful consideration of production
data and only when a substantial increase or decrease in production is likely to occur. In the example
above, the lower limitations would be in effect when production was at low levels (March through
August). During periods of significantly higher production (September through February), the higher
limitations would be in effect. In addition, a tiered or alternate set of limitations might be appropriate in
the case of special processes or product lines that operate during certain times only.
Permit writers could base thresholds for tiered limitations on an expected increase in production during
the term of the permit that will continue through the duration of the permit term. For example, if a facility
plans to add a process line and significantly expand production in year 3 of the permit term, the permit
could specify a higher tier of limitations that go into effect when the facility reports reaching a production
level specified in the permit.
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Permit writers must detail in the permit the thresholds and time frames when each tier applies, measures
of production, and special reporting requirements. Special reporting requirements include provisions such
as the following:
The facility notifying the permitting authority a specified number of business days before the
month it expects to be operating at a higher level of production and the duration this level of
production is expected to continue.
The facility reporting, in the discharge monitoring report, the level of production and the
limitation and standards applicable to that level.
A detailed discussion of the rationale and requirements for any tiered limitations should be provided in
the fact sheet for the permit.
Internal Outfalls
The NPDES regulations at § 122.45(h) give NPDES permit writers the authority to identify internal
outfalls when effluent limitations at the final outfall are impractical or infeasible. These internal
compliance points might be necessary to ensure proper treatment of persistent, bioaccumulative, and toxic
pollutants that are discharged in concentrations below analytic detection levels at the final effluent outfall
or other pollutants that may be diluted by flows (e.g., cooling water) not containing the pollutant. Some
effluent guidelines may require the use of internal outfalls unless the effluent limitations are adjusted
based on the dilution ratio of the process wastewater to the wastewater flow at the compliance point.
Examples of effluent guidelines with required internal compliance points include the Metal Finishing
effluent guidelines (Part 433) and the Pulp, Paper, and Paperboard effluent guidelines (Part 430).
Accordingly, the permit writer should identify any internal outfall monitoring that might be required by
the applicable effluent guidelines and include monitoring requirements in the final permit.
Effluent Guidelines Variances
The CWA and federal regulations provide limited mechanisms for variances from requirements in
effluent guidelines. An NPDES permit applicant must meet very specific data and variance application
deadline requirements before a variance may be granted. A variance provides a unique exception to a
particular requirement, and the permit writer should not expect to routinely receive variance requests.
Nevertheless, the permit writer should be aware of the major types of variances and the basic
requirements for each, because the permit writer will most likely be the person to conduct the initial
reviews of such requests before submitting them for review to the State Director (if applicable) or to EPA.
Variance applications are submitted by the NPDES permit applicant and must be submitted before the
close of the public comment period of the permit, except for Fundamentally Different Factors (PDF)
variance requests, which must be requested by the NPDES permit applicant within 180 days of the
effluent guidelines publication. The permit writer should consult § 124.62 for the specific procedures for
decisions regarding various types of variances. Exhibit 5-20 lists the available variances from effluent
guidelines.
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Exhibit 5-20 Variances from effluent guidelines
Legislation
(CWA section)
Type
Regulation
(40 CFR)
Approval authority
Application
deadline
301(g)
301(n)
L
Nonconventional
Pollutant
Fundamentally
Different Factors
(FDF)
Net Intake or
Net/Gross
Part 125, Subpart F
(Reserved)
Part 125, Subpart D
§ 122.45(g)
EPA Region
HQ delegated
authority
EPA Region
HQ delegated
authority
NPDES state
or EPA Region in
absence of approved
state NPDES program
During permit
comment period
180 days from the
date the limitation or
standard is published
intheFR
During permit
comment period
The following paragraphs further discuss the variances listed in Exhibit 5-20 and the factors that are
considered in a technical review of a variance request.
Nonconventional PollutantCWA Section 301 (g) Variance
CWA section 301(g) and the regulations at § 122.21(m)(2) provide for a variance from new or revised
BAT effluent guidelines for certain nonconventional pollutants because of local environmental factors, so
long as the discharger demonstrates that it is meeting BPT and that the discharge does not prevent
attainment of water quality standards and would not result in additional requirements on other point or
nonpoint sources. The pollutants for which a facility may request a CWA section 301(g) variance are
ammonia, chlorine, color, iron, and phenols (as measured by the colorimetric 4-aminoantipyrine [4AAP]
method). The CWA also provides a process to petition to include additional pollutants on this list.
Industries with facilities that have applied for CWA section 301(g) variances include Iron and Steel
Manufacturing (Part 420), Steam Electric Power Generating (Part 423), Inorganic Chemicals
Manufacturing (Part 415), Nonferrous Metals Manufacturing (Part 421), Aluminum Forming (Part 467),
and Pesticides Chemicals (Part 455) facilities.
In addition to meeting the application deadline, the discharger must file a variance application that meets
the following requirements:
The proposed modified requirements must result in compliance with BPT and water quality
standards of the receiving stream.
No additional treatment will be required of other point or nonpoint source dischargers as a result
of the variance approval.
The modified requirements will not interfere with attainment or maintenance of water quality to
protect public water supplies, or with protection and propagation of a balanced population of
shellfish, fish, and wildfowl, and will allow recreational activities in and on the water.
The modified requirements will not result in quantities of pollutants that can reasonably be
anticipated to pose an unacceptable risk to human health or the environment, cause acute or
chronic toxicity, or promote synergistic properties.
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The permit writer should review the request to ensure that it complies with each of the requirements for
this type of variance. This variance request can involve a great deal of water quality assessment, including
aquatic toxicity, mixing zone and dilution model analysis, and possible site-specific criterion
development. In addition, it might be necessary to assess many complex human health effects, including
carcinogenicity, teratogenicity, mutagenicity, bioaccumulation, and synergistic propensities. Permit
writers may use EPA's Draft Technical Guidance Manual for the Regulations Promulgated Pursuant to
Section 301 Cs) of the Clean Water Act of 1977 40 CFR Part 125 (Subpart F)
to assess a completed variance request.
Fundamentally Different FactorsPDF Variance
Alternative effluent limitations or standards different from the otherwise applicable requirements in
effluent guidelines may be authorized by EPA if an individual facility is fundamentally different with
respect to factors considered in establishing the limitations or standards otherwise applicable to that
facility's industrial category. Such a modification is known as a. fundamentally different factors (PDF)
variance.
Facilities must submit all PDF variance applications to the appropriate Director, as defined at § 122.2, no
later than 180 days from the date the limitations or standards are published in the PR [see CWA section
301(n)(2) and § 122.21(m)(l)(i)(B)(2)]. An PDF variance is not available to a new source subject to
NSPS.
EPA regulations at Part 125, Subpart D, authorizing the EPA Regional Administrators to establish
alternative limitations and standards, further detail the substantive criteria used to evaluate PDF variance
requests for direct dischargers. The regulations at § 125.3 l(d) identify six factors that may be considered
in determining if a facility is fundamentally different:
Nature or quality of pollutants contained in the raw process wastewater.
Volume of the process wastewater and effluent discharged.
Non-water quality environmental impact of control and treatment of the raw wasteload.
Energy requirements of the application of control and treatment technology.
Age, size, land availability, and configurations of discharger's equipment or facilities as well as
processes employed, process changes, and engineering aspects of the application of control
technology.
Cost of compliance with required control technology.
The Agency must determine whether, on the basis of one or more of those six factors, the facility in
question is fundamentally different from the facilities and factors considered by EPA in developing the
nationally applicable effluent guidelines. The regulation also lists four other factors that may not provide
a basis for an PDF variance:
Infeasibility of installation within the time allowed by the CWA.
Assertion that the national limitations cannot be achieved with the appropriate waste treatment
facilities installed (if the assertion is not based on one or more of the six PDF factors above).
A discharger's ability to pay for the required water treatment.
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The impact of a discharge on local receiving water quality.
In addition, under § 125.3 l(b)(3), a request for limitations less stringent than the national limitation may
be approved only if compliance with the national limitations would result in either of the following:
Removal cost wholly out of proportion to the removal cost considered during development of the
national limitations.
Non-water quality environmental impact (including energy requirements) fundamentally more
adverse than the impact considered during development of the national limitations.
The conditions for approval of a request to modify applicable pretreatment standards and factors
considered are the same as those for direct dischargers.
The legislative history of CWA section 301(n) underscores the necessity for the PDF variance applicant
to establish eligibility for the variance. EPA's regulations at § 125.32(b)(l) are explicit in imposing that
burden on the applicant. The applicant must show that the factors relating to the discharge controlled by
the applicant's permit, which are claimed to be fundamentally different are, in fact, fundamentally
different from those factors considered by the EPA in establishing the applicable effluent guidelines. The
pretreatment regulations incorporate a similar requirement at § 403.13(h)(9).
Intake Allowance or Net/Gross Variance
Some facilities might be unable to comply with effluent guidelines because of pollutants in their intake
water. Under certain circumstances, the NPDES regulations allow credit for pollutants in intake water.
Specifically, permit writers are authorized to grant net credits for the quantity of pollutants in the intake
water where (1) the applicable effluent guidelines specify that the guidelines are to be applied on a net
basis; or (2) the pollution control technology would, if properly installed and operated, meet applicable
effluent guidelines without the pollutants in the intake waters. The following requirements are included in
§ 122.45(g) for establishing net limitations:
Credit for conventional pollutants, such as BOD5 or TSS, are only authorized where the
constituents resulting in the effluent BOD5 and the TSS are similar between the intake water and
the discharge.
Credit is authorized only up to the extent necessary to meet the applicable limitation or standard,
with a maximum value equal to the influent concentration.
Intake water must be taken from the same body of water into which the discharge is made.
Net credits do not apply to the discharge of raw water clarifier sludge generated during the
treatment of intake water.
Permit writers must include influent monitoring in the permit when this type of variance is granted.
Thermal DischargeCWA Section 316(a) Variance
CWA section 316(a) and the regulations at § 122.21(m)(6) provide for variances from thermal effluent
limitations in NPDES permits. EPA has only promulgated thermal limitations in effluent guidelines for
two industrial sectors: Beet Sugar Processing Subcategory of the Sugar Processing Point Source Category
(Part 409 Subpart A) and the Cement Manufacturing Point Source Category (Part 411, Subparts A and B).
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Most thermal limitations are based on water quality standards, so most thermal variances actually are not
true technology-based variances. Dischargers must apply for a thermal discharge variance with its permit
application if the thermal effluent limitation is based on an effluent guideline or during the permit
comment period if the thermal effluent limitation is based on a WQBEL.
Regulations for submitting and reviewing thermal discharge variance requests are promulgated at Part
125, Subpart H. The approval authority for a thermal discharge variance request is the state permitting
authority or the EPA Region if there is no approved state NPDES program. Less stringent alternative
thermal effluent limitations may be included in permits if the discharger properly demonstrates that such
effluent limitations are more stringent than necessary to assure the protection and propagation of a
balanced, indigenous community of shellfish, fish and wildlife in and on the body of water into which the
discharge is made, taking into account the cumulative impact of its thermal discharge together with all
other significant impacts on the species affected. Once a variance is granted, the discharger must still
reapply for the variance each permit term. The majority of thermal variance requests are from power
plants seeking relief from water-quality based effluent limitations.
Climate Change Considerations
Evaluation of requests for variances under CWA section 316(a) requires consideration of the change
to the ambient water temperature because of an effluent discharge. The studies provided by
applicants to support their requests frequently include historical thermal data for the receiving water.
Permitting authorities should be aware that the effects of global climate change could alter the thermal
profile of some receiving waters making the historical record of thermal conditions less representative
of future conditions. Where appropriate, water quality models should take these potential changes into
account.
5.2.2.8 Step 8: Apply Additional Requirements in Effluent Guidelines
The effluent guidelines could provide additional requirements for permit writers to consider when
applying them in NPDES permits.
Industrial Stormwater
Industrial stormwater is sometimes regulated by effluent guidelines. In particular, effluent guidelines
often regulate stormwater for industrial activities that are unsheltered (e.g., mining, outdoor processing,
outside storage of product materials). Examples of contaminated stormwater regulated by effluent
guidelines include the Concentrated Animal Feeding Operations (Part 412), Fertilizer Manufacturing (Part
418), Petroleum Refining (Part 419), Iron and Steel Manufacturing (Part 420), Pulp, Paper, and
Paperboard (Part 430), Metal Products and Machinery (Part 438), and Ore Mining and Dressing (Part
440) point source categories. The permit writer should identify any specific stormwater controls that may
be required by the applicable effluent guidelines accordingly.
Stormwater not regulated by effluent guidelines that is commingled with process wastewater will require
the adjustment of the effluent limitations as discussed in Step 6 above. Section 2.3.2.3 of this manual
provides additional information about stormwater discharges associated with industrial activities.
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Identify the Analytical Methods for Measuring Compliance with TBELs
The permit writer should ensure that the permit specifies the use of the correct analytical methods for
demonstrating compliance with TBELs derived from effluent guidelines. The effluent guidelines often
require specific analytical methods. For example, the General Definitions section of the Meat and Poultry
Products effluent guidelines [§ 432.2(1)] states, "The approved methods of analysis for the following six
parameters [Ammonia (as N), BOD5, Oil and Grease (O&G), O&G as hexane extractable material
(HEM), Total Nitrogen, TSS] are found in Table IB in [§] 136.3. The nitrate/nitrite part of total
nitrogen may also be measured by EPA Method 300.0 (incorporated by reference, see § 432.5)."
Section 8.3 of this manual provides additional information on analytical methods in the NPDES
permitting process.
Documentation and Recordkeeping Requirements
Specific documentation and recordkeeping requirements (e.g., solvent management plans, BMP plans,
alternative monitoring requirements) may be included in the applicable effluent guidelines. The permit
writer should ensure that the documentation and recordkeeping requirements are included in the NPDES
permit. For example, to use the alternative monitoring compliance method for controlling toxic organics
in the Metal Finishing effluent guidelines, the NPDES permit applicant must not only make a certification
statement (see Exhibit 5-15), but must also "submit a solvent management plan that specifies to the
satisfaction of the permitting authority (or, in the case of indirect dischargers, the control authority) the
toxic organic compounds used; the method of disposal used instead of dumping, such as reclamation,
contract hauling, or incineration; and procedures for ensuring that toxic organics do not routinely spill or
leak into the wastewater" as required by § 433.12(b). Other examples of such documentation and
recordkeeping requirements include the BMP Plans used in the Oil and Gas Extraction (Part 435) and the
Concentrated Aquatic Animal Production effluent guidelines (Part 451), the pollution prevention
alternative in the Pesticide Chemicals effluent guidelines (Part 455), and alternative monitoring
requirements (e.g., certification in lieu of monitoring for chloroform, in the Pulp, Paper, and Paperboard
effluent guidelines (Part 430).
5.2.2.9 Step 9: Document the Application of Effluent Guidelines in the Fact Sheet
Permit writers need to document their application of effluent guidelines in the NPDES permit fact sheet.
The permit writer should clearly identify the data and information used to determine the applicable
effluent guidelines and how that information was used to derive effluent limitations for the permit. The
information in the fact sheet should provide the NPDES permit applicant and the public a transparent,
reproducible, and defensible description of how the NPDES permit properly incorporates effluent
guidelines.
Similarly, permit writer should also document the rationale for concluding that there are no applicable
effluent guidelines for a discharge or pollutant. In such cases, TBELs may be determined by the permit
writer on a case-by-case basis as discussed in section 5.2.3 below.
5.2.3 Case-Jby-Case TBELs for Industrial Dischargers
As previously stated, § 125.3 (a) indicates that technology-based treatment requirements under CWA
section 301(b) represent the minimum level of control that must be imposed in an NPDES permit.
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Where EPA-promulgated effluent guidelines are not applicable to a non-POTW discharge, such
requirements are established on a case-by-case basis using BPJ.
5.2.3.1 Legal Authority to Establish Case-by-Case TBELs
Case-by-case TBELs are developed pursuant to CWA section 402(a)(l), which authorizes the EPA
Administrator to issue a permit that will meet either all applicable requirements developed under the
authority of other sections of the CWA (e.g., technology-based treatment standards, water quality
standards, ocean discharge criteria) or, before taking the necessary implementing actions related to those
requirements, "such conditions as the Administrator determines are necessary to carry out the provisions
of this Act." The regulation at § 125.3(c)(2) specifically cites this section of the CWA, stating that
technology-based treatment requirements may be imposed in a permit "on a case-by-case basis under
section 402(a)(l) of the Act, to the extent that EPA-promulgated effluent limitations are inapplicable."
Further, § 125.3(c)(3) indicates that "where promulgated effluent limitations guidelines only apply to
certain aspects of the discharger's operation, or to certain pollutants, other aspects or activities are subject
to regulation on a case-by-case basis to carry out the provisions of the Act." When establishing case-by-
case effluent limitations using BPJ, the permit writer should cite in the fact sheet or statement of basis
both the approach used to develop the limitations, which is discussed further below, and how the
limitations carry out the intent and requirements of the CWA and the NPDES regulations.
5.2.3.2 Identifying the Need for Case-by-Case TBELs
As noted above, case-by-case TBELs are established in situations where EPA promulgated effluent
guidelines are inapplicable. That includes situations such as the following:
When EPA has not yet promulgated effluent guidelines for the point source category to which a
facility belongs (e.g., a facility that produced distilled and blended liquors [SIC code 2085] and is
part of the miscellaneous foods and beverages category, which does not now have any applicable
effluent guidelines).
When effluent guidelines are available for the industry category, but no effluent guidelines are
available for the facility subcategory (e.g., discharges from coalbed methane wells are not now
regulated by effluent guidelines; however, EPA considers the coalbed methane industrial sector
as a potential new subcategory of the existing Oil and Gas Extraction point source category [Part
435] because of the similar industrial operations performed [i.e., drilling for natural gas
extraction]).
When effluent guidelines are available for the industry category but are not applicable to the
NPDES permit applicant (e.g., facilities that do not perform the industrial operation triggering
applicability of the effluent guidelines or do not meet the production or wastewater flow cutoff
applicability thresholds of the effluent guidelines). For example, assume that the poultry
slaughterhouse in Example 2 of Exhibit 5-13 above produces 50 million pounds of whole, halved,
quarter or smaller meat cuts annually. In that case, any TBELs for the facility would be case-by-
case limitations developed using BPJ because the facility is below the annual production
threshold of 100 million pounds listed in the effluent guideline (Part 432, Subpart K).
When effluent guidelines are available for the industry category, but no effluent guidelines
requirements are available for the pollutant of concern (e.g., a facility is regulated by the effluent
guidelines for Pesticide Chemicals [Part 455] but discharges a pesticide that is not regulated by
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these effluent guidelines). The permit writer should make sure that the pollutant of concern is not
already controlled by the effluent guidelines and was not considered by EPA when the Agency
developed the effluent guidelines.
Generally, case-by-case limitations are appropriate when at least one of the conditions listed above
applies and the pollutant is present, or expected to be present, in the discharge in amounts that can be
treated or otherwise removed (e.g., implementation of pollution prevention measures). The resources
listed in sections 5.2.2.2 above and 5.2.3.4 below will help the permit writer in making such
determinations. For example, EPA's effluent guidelines planning support documents on EPA's Effluent
Guidelines Biennial Plan Website identify facilities and
industrial sectors that currently are not regulated by effluent guidelines.
5,2,3,3 TBELs
The NPDES regulations at § 125.3(c)(2) require that permit writers developing case-by-case effluent
limitations consider the following:
The appropriate technology for the category class of point sources of which the applicant is a
member, based on all available information.
Any unique factors relating to the applicant.
The regulations also require that, in setting case-by-case limitations, the permit writer consider several
specific factors established in § 125.3(d) to select a model treatment technology and derive effluent
limitations on the basis of that treatment technology. That process and the factors considered by the
permit writer are the same factors required to be considered by EPA in developing effluent guidelines
and, therefore, are often referred to as the CWA section 304(b) factors. The factors are summarized below
in Exhibit 5-21. The permit writer evaluates case-by-case limitations based on BPT, BCT, and BAT and
uses the more stringent technology level of control for each pollutant of concern.
Exhibit 5-21 Summary of factors considered when developing case-by-case TBELs
For BPT requirements (all pollutants)
The age of equipment and facilities involved*
The process(es) employed*
The engineering aspects of the application of various types of control techniques*
Process changes*
Non-water quality environmental impact including energy requirements*
The total cost of application of technology in relation to the effluent reduction benefits to be achieved from such
application
For BCT requirements (conventional pollutants)
All items in the BPT requirements indicated by an asterisk (*) above
The reasonableness of the relationship between the costs of attaining a reduction in effluent and the derived
effluent reduction benefits
The comparison of the cost and level of reduction of such pollutants from the discharge of POTWs to the cost
and level of reduction of such pollutants from a class or category of industrial sources
For BAT requirements (toxic and non-conventional pollutants)
All items in the BPT requirements indicated by an asterisk (*) above
The cost of achieving such effluent reduction
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The CWA also gives the permit writer the authority to consider process changes to evaluate case-by-case
limitations. As previously stated, technology-based controls in NPDES permits are performance-based
measures. EPA incorporates technology-based controls in NPDES permits that correspond to the
application of an identified technology (including process changes) but does not require dischargers to
install the identified technology. Therefore, EPA leaves to each facility the discretion to select the
technology design or process changes necessary to meet the TBELs specified in the NPDES permit.
The permit writer might need to establish a monitoring-only requirement in the current NPDES permit to
identify pollutants of concern and potential case-by-case limitations for the subsequent NPDES permit
renewal.
5.2.3.4 Resources for Developing Case-by-Case TBELs
There are numerous resources for identifying candidates for model technologies or process changes and
developing case-by-case TBELs using BPJ. Exhibit 5-22 lists some example references that permit
writers can use to derive such limitations.
5.2.3.5 Statistical Considerations When Establishing Case-by-Case TBELs
The quality of the effluent from a treatment facility will normally vary over time. If, for example, BOD5
data for a typical treatment plant were plotted against time, one would observe day-to-day variations of
effluent concentrations. Some of that behavior can be described by constructing a frequency-
concentration plot. From the plot, one could observe that for most of the time, BOD5 concentrations are
near some average value. Any treatment system can be described using the mean concentration of the
parameter of interest (i.e., the long-term average) and the variance (or coefficient of variation) and by
assuming a particular statistical distribution (usually lognormal).
When developing a case-by-case limitation, permit writers can use an approach consistent with the
statistical approach EPA has used to develop effluent guidelines. Specifically, the maximum daily
limitation could be calculated by multiplying the long-term average achievable by implementation of the
model technology or process change by a daily variability factor determined from the statistical properties
of a lognormal distribution. The average monthly limitation can be calculated similarly except that the
variability factor corresponds to the distribution of monthly averages instead of daily concentration
measurements. The daily variability factor is a statistical factor defined as the ratio of the estimated 99th
percentile of a distribution of daily values divided by the mean of the distribution. Similarly, the monthly
variability factor is typically defined as the estimated 95th percentile of the distribution of monthly
averages divided by the mean of the distribution of monthly averages.
A modified delta-lognormal distribution could be fit to concentration data and variability factors
computed for the facility distribution. The modified delta-lognormal distribution models the data as a
mixture of measured values and observations recorded as values less than the detectable level. This
distribution often is selected because the data for many analytes consist of such a mixture of measured
values and results below the detectable level. The modified delta-lognormal distribution assumes that all
non-detected results have a value equal to the detection limitations and that the detected values follow a
lognormal distribution.
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Exhibit 5-22 Tools for developing case-by-case TBELs using BPJ
Permit file information
Current and previous NPDES application forms.
Previous NPDES permit and fact sheet.
Discharge monitoring reports.
Compliance inspection reports.
Information from existing facilities and permits
NPDES Individual and General Permits for other NPDES permits issued to facilities in the same region or state,
or that include case-by-case limitations for the same pollutants.
Toxicity reduction evaluations for selected industries.
Other media permit files (e.g., Resource Conservation and Recovery Act [RCRA] permit applications and Spill
Prevention Countermeasure and Control [SPCC] plans.
ICIS-NPDES data.
Literature (e.g., technical journals and books).
Effluent guidelines development and planning information
Industry experts within EPA headquarters, EPA Regions, and states .
Development Documents, CWA section 308 questionnaires, screening and verification data, proposed and final
regulations, contractor's reports, and project officer contacts .
EPA's Technical Support Documents and records
supporting EPA's biennial effluent guidelines program plans also provide additional useful information. In
particular, such resources provide a sample of the current limitation and latest developments in industrial
pollutant prevention, water conservation, and wastewater treatment. The Technical Support Documents also
identify industrial sectors not currently regulated by effluent guidelines.
Statistical guidance
Effluent Guidelines Technical Development Support Documents, such as the Development Document for Final
Effluent Limitations Guidelines and Standards for the Iron and Steel Manufacturing Point Source Category
.
Economics guidance
Protocol and Workbook for Determining Economic Achievability for NPDES Permits3
and .
Guidance for BMP-based limitations
Guidance Manual for Developing Best Management Practices (BMPs)w
.
Storm Water Management for Industrial Activities: Developing Pollution Prevention Plans and
BMPs .
For more details on EPA's use of statistical methods for developing effluent guidelines, refer to
Development Document for Final Effluent Limitations Guidelines and Standards for the Iron and Steel
Manufacturing Point Source Category .
5,2,3,6 Documenting TBELs in the Permit
Permit writers will need to document the development of case-by-case limitations in the NPDES permit
fact sheet. The permit writer should clearly identify the data and information used in developing these
effluent limitations and how that information was used. The permit writer also should document the
rationale for concluding that there are no applicable effluent guidelines for the industrial wastewater or
pollutant discharge. The information in the fact sheet should provide the NPDES permit applicant and the
public a transparent, reproducible, and defensible description of how the BPJ limitations comply with the
CWA and EPA regulations.
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1 U.S. Environmental Protection Agency. 1985. Draft Guidance for NPDES Permits and Compliance PersonnelSecondary
Treatment Redefinition. U.S. Environmental Protection Agency. Office of Water Enforcement and Permits. Washington, DC.
2 U.S. Environmental Protection Agency. 1994. Amended Section 301 (h) Technical Support Document. EPA-842-B-94-007.
U.S. Environmental Protection Agency. Office of Wetlands Oceans and Watersheds, Washington, DC.
3 U.S. Environmental Protection Agency. 1977. Interim Final Supplement for Pretreatment to the Development Document for the
Petroleum Refining Industry Existing Point Source Category, EPA-440-1-76-083A. Page 92. U.S. Environmental Protection
Agency, Office of Water and Hazardous Materials, Washington, DC. Publication available on NEPIS Website
as document 440176083A.
4 Boomazian, Linda and Mary Smith. 2006. New Source Dates for Direct and Indirect Dischargers. U.S. Environmental
Protection Agency, Office of Water Memorandum. September 28, 2006. .
5 U.S. Environmental Protection Agency. 1987. Development Document for Effluent Limitations Guidelines and Standards for
the Organic Chemicals, Plastics and Synthetic Fibers Point Source Category. EPA 440-1-87-009. Page IX-9.
.
6 Jordan, J.W. 1984. Calculations of Production-Based Effluent Limits. U.S. Environmental Protection Agency, Office of Water,
Washington, DC. Memorandum, December 18, 1984. .
U.S. Environmental Protection Agency. 2001. Permit Guidance Document: Transportation Equipment Cleaning Point Source
Category (40 CFR 442), p. 30. EPA-821-R-01-021. U.S. Environmental Protection Agency, Office of Water, Washington, DC.
.
8 U. S. Environmental Protection Agency. 2004. Technical Development Document for the Final Effluent Limitations Guidelines
and Standards for the Meat andPoultry Products Point Source Category (40 CFR 432), EPA-821-R-04-011. U.S. Environmental
Protection Agency, Office of Water, Washington, DC. .
9 Putnam, Hayes and Bartlett, Inc. 1982. Protocol and WorkbookforDeterminingEconomicAchievability for National Pollutant
Discharge Elimination System Permits. U.S. Environmental Protection Agency, Permits Division, Washington, DC.
and
10 U.S. Environmental Protection Agency. 1993. Guidance Manual for Developing Best Management Practices (BMP). EPA
833-B-93-004. U.S. Environmental Protection Agency, Office of Water, Washington, DC.
.
11 U.S. Environmental Protection Agency. 1992. Storm Water Management for Industrial Activities: Developing Pollution
Prevention Plans andBMPs. EPA 832-R-92-006. U.S. Environmental Protection Agency, Office of Water, Washington, DC.
.
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CHAPTER 6. Water Quality-Based Effluent Limitations
When drafting a National Pollutant Discharge Elimination System (NPDES) permit, a permit writer must
consider the impact of the proposed discharge on the quality of the receiving water. Water quality goals
for a waterbody are defined by state water quality standards. By analyzing the effect of a discharge on the
receiving water, a permit writer could find that technology-based effluent limitations (TBELs) alone will
not achieve the applicable water quality standards. In such cases, the Clean Water Act (CWA) and its
implementing regulations require development of water quality-based effluent limitations (WQBELs).
WQBELs help meet the CWA objective of restoring and maintaining the chemical, physical, and
biological integrity of the nation's waters and the goal of water quality that provides for the protection
and propagation offish, shellfish, and wildlife and recreation in and on the water (fishable/swimmable).
WQBELs are designed to protect water quality by ensuring that water quality standards are met in the
receiving water. On the basis of the requirements of Title 40 of the Code of Federal Regulations (CFR)
125.3(a), additional or more stringent effluent limitations and conditions, such as WQBELs, are imposed
when TBELs are not sufficient to protect water quality. Exhibit 6-1 illustrates the relationship between
TBELs and WQBELs in an NPDES permit, as well as the determination of final effluent limitations.
Exhibit 6-1 Developing effluent limitations
Develop technology-based effluent limitations
(TBELs)
Chapter 5
Develop water quality-based effluent
limitations (WQBELs)
Chapter 6
Determine final effluent limitations that meet
technology and water quality standards and
anti-backsliding requirements
Chapter 7
CWA section 301(b)(l)(C) requires that permits include any effluent limitations necessary to meet water
quality standards. As illustrated above, to satisfy that requirement, permit writers implement a process to
determine when existing effluent limitations (e.g., TBELs) and existing effluent quality are not sufficient
to comply with water quality standards and to, where necessary, develop WQBELs. Exhibit 6-2 illustrates
the four basic parts of the standards-to-permits process used to assess the need for and develop WQBELs.
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After completing that process, the permit writer determines the final effluent limitations, includes any
compliance schedules and interim effluent limitations, as appropriate, and documents all his or her
decisions and calculations.
Exhibit 6-2 Standards-to-permits process
Determine Applicable Water Quality
Standards
Characterize Effluent and Receiving Water
Determine the Need for WQBELs
Calculate WQBELs
This chapter provides basic information on the standards-to-permits process. For more detailed
information on water quality standards and water quality-based permitting, and some of the specific
topics discussed in this chapter, refer to the NPDES Website and Water Quality
Standards Website .
6.1 Determine Applicable Water Quality Standards
CWA section 303(c) and Part 131 establish the framework for water quality standards. The CWA and
implementing regulations require states to develop and, from time to time, revise water quality standards
applicable to waters of the United States, or segments of such waterbodies, that are in the jurisdiction of
the state. States must review their water quality standards at least once every 3 years and revise them as
appropriate. Wherever attainable, water quality standards should protect water quality that provides for
the protection and propagation offish, shellfish and wildlife, and recreation in and on the water (i.e., the
CWA section W\(a)(2)jishable/swimmable goal). In establishing standards, states must consider the use
and value of their waters for public water supplies, propagation offish and wildlife, recreation, agriculture
and industrial purposes, and navigation. The U.S. Environmental Protection Agency (EPA) has provided
information regarding procedures for developing water quality standards in the Water Quality Standards
Regulation at Part 131 and EPA's Water Quality Standards Handbook: Second Edition1
(hereafter WQSHandbook). Under CWA section
510, states may develop water quality standards that are more stringent than those required by the CWA.
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EPA Regions review and approve or disapprove new and revised water quality standards adopted by
states. The purpose of EPA's review is to ensure that the new and revised water quality standards meet
the requirements of the CWA and the Water Quality Standards Regulation. Water quality standards
adopted and submitted to EPA after May 30, 2000, must be approved by EPA before they may be used to
implement the CWA (e.g., used in NPDES permitting). If an EPA Region disapproves a submitted new or
revised state water quality standard, and the state does not adopt the necessary changes within 90 days of
notification of the disapproval, EPA must promptly propose and promulgate a replacement standard [see
§ 131.22(a)].
When writing an NPDES permit, the permit writer must identify and use the state water quality standards
in effect for CWA purposes. EPA maintains a compilation of current state water quality standards on the
Water Quality Standards: State. Tribal. & Territorial Standards Website
. In addition, EPA's Water Quality Standards: Laws and
Regulations Website provides federally promulgated standards
applicable to specific states. The remainder of this section provides permit writers with a general
overview of water quality standards and how they are implemented in NPDES permits.
6.1.1 Components of Water Quality Standards
Water quality standards comprise three parts:
Designated uses.
Numeric and/or narrative water quality criteria.
Antidegradation policy.
Each of those three components, along with general policies that also may be included in state water
quality standards, is described below.
6.1.1.1 Designated Uses (§131.10)
The first part of a state's water quality standards is a classification system for waterbodies based on the
expected uses of those waterbodies. The uses in this system are called designated uses. The regulations at
§131.10(a) describe various uses of waters that are considered desirable and that must be considered
when establishing water quality standards. Those uses include public water supplies, propagation offish,
shellfish, and wildlife, recreation in and on the water, agricultural, industrial, and other purposes
including navigation. The regulations allow states to designate more specific uses (e.g., cold water aquatic
life) [see § 131.10(c)] or uses not specifically mentioned in the CWA, with the exception of waste
transport and assimilation, which are not acceptable designated uses [see § 131.10(a)]. States must also
consider and ensure the attainment and maintenance of the water quality standards of downstream waters
when establishing designated uses [see § 131.10(b)].
The regulations in § 131.10(j) effectively establish a rebuttable presumption that the uses in CWA section
101(a)(2) (fishable/swimmable) are attainable. If a state fails to designate a given waterbody for such
uses, or wishes to remove such uses, it must provide appropriate documentation demonstrating why such
uses are not attainable. This analysis is commonly called a Use Attainability Analysis (UAA) (see
§ 131.3(g) and section 6.1.2.1 below).
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6.1.1.2 Water Quality Criteria (§131.11)
The second part of a state's water quality standards is the set of water quality criteria sufficient to support
the designated uses of each waterbody. EPA's Water Quality Standards Regulation at § 131.11 (a) requires
states to adopt water quality criteria using sound scientific rationale and to include sufficient parameters
or constituents to protect the designated use. If a waterbody has multiple use designations, the criteria
must support the most sensitive use. The regulation at § 131.1 l(b) allows states to adopt both numeric and
narrative water quality criteria. Numeric water quality criteria are developed for specific parameters to
protect aquatic life and human health and, in some cases, wildlife from the deleterious effects of
pollutants. States establish narrative criteria where numeric criteria cannot be established, or to
supplement numeric criteria. Criteria newly adopted or revised on or after May 30, 2000, do not become
effective for purposes of the CWA until approved by EPA [see § 131.21 (c)].
CWA section 304(a) directs EPA to develop, publish, and, from time to time, revise criteria for water
quality accurately reflecting the latest scientific knowledge on the following:
The kind and extent of all identifiable effects on health and welfare, including effects on aquatic
life and recreational uses, that may be expected from the presence of pollutants in any body of
water.
The concentration and dispersal of pollutants or their byproducts through biological, physical, and
chemical processes.
The effects of pollutants on biological community diversity, productivity, and stability.
EPA's recommended criteria developed under CWA section 304(a) assist states in developing their water
quality standards. EPA's numeric criteria are ambient levels of individual pollutants or parameters or they
describe conditions of a waterbody that, if met, generally will protect the CWA section 101(a)(2) fishable
and swimmable uses. EPA's recommended criteria developed under CWA section 304(a) do not reflect
consideration of economic impacts or the technological feasibility of meeting the chemical concentrations
in ambient water. EPA provides a table of the nationally recommended CWA section 304(a) criteria on
the National Recommended Water Quality Criteria Website . The
regulation at § 131.11(b)(l) indicates that, in establishing numeric criteria, states may (1) adopt EPA's
recommended criteria published under CWA section 304(a), (2) adopt those criteria modified to reflect
site-specific conditions, or (3) adopt criteria based on other scientifically defensible methods.
CWA section 303(c)(2)(B) specifically requires states to adopt numeric criteria for CWA section 307(a)
toxic (priority) pollutants for which EPA has published recommended criteria if the discharge or presence
of the pollutant can reasonably be expected to interfere with designated uses. Furthermore, § 131.1 l(a)(2)
requires states to review water quality data and information on discharges to identify specific water
bodies where toxic pollutants might be adversely affecting water quality or attainment of designated uses
or where levels of toxic pollutants would warrant concern and to adopt criteria for such toxic pollutants
applicable to the waterbody that are sufficient to protect the designated use. As discussed in section 1.2
and presented in Exhibit C-l in Appendix C of this manual, the CWA section 307(a) list contains
65 compounds and families of compounds, which EPA has interpreted to include 126 toxic (priority)
pollutants.
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Numeric CriteriaAquatic Life
Numeric criteria for the protection of aquatic life are designed to protect aquatic organisms, including
both plants and animals. EPA's aquatic life criteria address both short-term (acute) and long-term
(chronic) effects on both freshwater and saltwater species. Each of those criteria generally consists of
three components:
Magnitude: The level of pollutant (or pollutant parameter), usually expressed as a concentration,
that is allowable.
Duration: The period (averaging period) over which the in-stream concentration is averaged for
comparison with criteria concentrations.
Frequency: How often criteria may be exceeded.
Are criteria and effluent limitations expressed in the same terms?
Generally, criteria and effluent limitations are not expressed in the same terms. As discussed above,
criteria are generally expressed as a magnitude, duration and frequency. Effluent limitations in NPDES
permits are generally expressed as a magnitude (e.g., milligrams per liter, micrograms per liter) and an
averaging period (e.g., maximum daily, average weekly, average monthly). A permit writer should be
aware of the procedures used by his or her permitting authority to appropriately reflect the magnitude,
duration, and frequency components of aquatic life criteria when determining the need for and
calculating effluent limitations for NPDES permits. Typically, the components of the criteria are
addressed in water quality models through the use of statistically derived receiving water and effluent
flow values that ensure that criteria are met under critical conditions (see section 6.2 below).
Exhibit 6-3 is an example of freshwater aquatic life criteria for cadmium from the National
Recommended Water Quality Criteria Website and at 66 FR
18935, April 12, 2001, Notice of Availability of 2001 Update: Aquatic Life Criteria Document for
Cadmium .
Exhibit 6-3 Aquatic life criteria example: Cadmium (dissolved)
Except possibly where a locally important species is unusually sensitive, freshwater aquatic organisms and their
uses should not be affected unacceptably if
Chronic criterion:
The 4-day average concentration (in micrograms per liter [ug/L]) does not exceed the numerical value given by
e(o.7409[in(hardness)]-4.7i9) (1 101672 - [(In hardness)(0.041838)]) more than once every 3 years on average.
Acute criterion:
The 24-hour average concentration (in ug/L) does not exceed the numerical value given by
ed.oi66[in(hardness)]-3.924) (1136672 _ [(|n hardness)(0.041838)]) more than once every 3 years on average.
It is apparent that the acute and chronic aquatic life criteria for cadmium are not simply single numbers.
Rather, they are expressed as a magnitude, a duration (4-day average or 24-hour average), and a
frequency (not more than once every 3 years). Furthermore, the magnitude is expressed by a formula that
is hardness-dependent, as is the case for most criteria for metals.
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The magnitude of other aquatic life criteria can vary according to other conditions in the water or even
based on the presence or absence of certain aquatic life. For example, EPA's 1999 recommended
ammonia criteria vary according to pH, temperature, the presence or absence of salmonid species, and the
presence or absence of early life stages offish. A permit writer must be aware of the applicable criteria
and any state regulations, policies, and procedures for interpreting numeric criteria and for implementing
the criteria in NPDES permits. The durations of aquatic life criteria vary as well. For example, EPA's
criteria recommendations for ammonia include a 30-day average chronic criterion. Also, many acute
criteria for toxic pollutants are expressed as a 1-hour average. The frequency component of most aquatic
life criteria specifies that they should be exceeded no more than once every three years.
Some states have adopted numeric criteria for nutrients as part of their water quality standards. EPA has
developed nutrient criteria recommendations that are numeric values for both causative (phosphorus and
nitrogen) and response (chlorophyll a and turbidity) variables associated with the prevention and
assessment of eutrophic conditions. EPA's recommended nutrient criteria are different from most of its
other recommended criteria, such as the criteria for cadmium and ammonia. First, EPA's recommended
nutrient criteria are ecoregional rather than nationally applicable criteria, and they can be refined and
localized using nutrient criteria technical guidance manuals. Second, the recommended nutrient criteria
represent conditions of surface waters that have minimal impacts caused by human activities rather than
values derived from laboratory toxicity testing. Third, the recommended nutrient criteria are do not
include specific duration or frequency components; however, the ecoregional nutrient criteria documents
indicate that states may adopt seasonal or annual averaging periods for nutrient criteria instead of the
1-hour, 24-hour, or 4-day average durations typical of aquatic life criteria for toxic pollutants. The
ecoregional nutrient criteria documents, technical guidance manuals, and other information on EPA's
nutrient criteria recommendations, are available on the Water Quality Criteria for Nitrogen and
Phosphorus Pollution Website .
Water quality standards also typically include aquatic life criteria for parameters such as temperature and
pH that are not chemical constituents. Criteria for pH generally are expressed as an acceptable pH range
in the waterbody. Temperature criteria might be expressed as both absolute temperature values (e.g.,
temperature may not exceed 18 degrees Celsius [°C]) and restrictions on causing changes in temperature
in the waterbody (e.g., discharges may not warm receiving waters by more than 0.5 °C).
In addition to criteria for individual pollutants or pollutant parameters, many states include in their water
quality standards criteria for dissolved oxygen. Often, criteria for dissolved oxygen are addressed by
modeling and limiting discharges of oxygen-demanding pollutants such as biochemical oxygen demand
(BOD), chemical oxygen demand (COD), and nutrients (phosphorus and nitrogen).
Finally, states could also include in their water quality standards numeric criteria to address the effect of
mixtures of pollutants. For example, whole effluent toxicity (WET) criteria protect the waterbody from
the aggregate and synergistic toxic effects of a mixture of pollutants. WET is discussed in detail later in
this chapter.
Numeric CriteriaHuman Health
Human health criteria for toxic pollutants are designed to protect people from exposure resulting from
consumption offish or other aquatic organisms (e.g., mussels, crayfish) or from consumption of both
water and aquatic organisms. These criteria express the highest concentrations of a pollutant that are not
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expected to pose significant long-term risk to human health. Exhibit 6-4 is an example of human health
criteria for dichlorobromomethane.
Exhibit 6-4 Human health criteria example: Dichlorobromomethane
For the protection of human health from the potential carcinogenic effects of dichlorobromomethane through
ingestion of water and contaminated aquatic organisms, the ambient water criterion is determined to be 0.55 ug/L.
For the protection of human health from the potential carcinogenic effects of dichlorobromomethane through
ingestion contaminated aquatic organisms alone, the ambient water criterion is determined to be 17 ug/L.
These values were calculated based on a national default freshwater/estuarine fish consumption rate of
17.5 grams per day.
Other criteria for protection of human health (e.g., bacteria criteria) consider a shorter-term exposure
through uses of the waterbody such as contact recreation. EPA's current bacteria criteria
recommendations use enterococci and Escherichia coli bacteria as indicators and include two
components: a geometric mean value and a single sample maximum value. EPA has developed
information on implementing those criteria in water quality standards on the Microbial (Pathogen) Water
Quality Criteria Website .
Other Numeric Criteria
In addition to aquatic life and human health criteria, some state water quality standards include other
forms of numeric criteria, such as wildlife, sediment, and biocriteria.
Wildlife criteria are derived to establish ambient concentrations of chemicals that, if not exceeded, will
protect mammals and birds from adverse impacts resulting from exposure to those chemicals through
consumption of aquatic organisms and water. EPA established four numeric criteria to protect wildlife in
the Great Lakes system in its Final Water Quality Guidance for the Great Lakes System
(60 FR 15387, March 23, 1995).
In a healthy aquatic community, sediments provide a habitat for many living organisms. Controlling the
concentration of pollutants in the sediment helps to protect bottom-dwelling species and prevents harmful
toxins from moving up the food chain and accumulating in the tissue of animals at progressively higher
levels. For more information on this topic, see EPA's Suspended and Bedded Sediments Website
.
The presence, condition and numbers of types offish, insects, algae, plants, and other organisms are data
that, together, provide direct, accurate information about the health of specific bodies of water. Biological
criteria (biocriteria) are narrative or numeric expressions that describe the reference biological integrity
(structure and function) of aquatic communities inhabiting waters of a given designated aquatic life use.
Biocriteria are based on the numbers and kinds of organisms present and are regulatory-based biological
measurements. They are used as a way of describing the qualities that must be present to support a desired
condition in a waterbody, and they serve as the standard against which biological assessment results are
compared. EPA's Biocriteria: Uses of Data in NPDES Permits Website
provides more information on the use of
bioassessment information.
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Narrative Criteria
All states have adopted narrative water quality criteria to supplement numeric criteria. Narrative criteria
are statements that describe the desired water quality goal for a waterbody. Narrative criteria, for
example, might require that discharges be "free from toxics in toxic amounts" or be "free of objectionable
color, odor, taste, and turbidity." Narrative criteria can be the basis for limiting specific pollutants for
which the state does not have numeric criteria [§ 122.44(d)(l)(vi)] or they can be used as the basis for
limiting toxicity using WET requirements where the toxicity has not yet been traced to a specific pollutant
or pollutants [§ 122.44(d)(l)(v)]. For toxic pollutants, EPA's Water Quality Standards Regulation at
§ 131.1 l(a)(2) requires states to develop implementation procedures for toxics narrative criteria that
address how the state intends to regulate point source discharges of toxic pollutants to water quality
limited segments.
6.1.1.3 Antidegradation Policy (§131.12)
The third part of a state's water quality standards is its antidegradation policy. Each state is required to
adopt an antidegradation policy consistent with EPA's antidegradation regulations at § 131.12. A state's
antidegradation policy specifies the framework to be used in making decisions about proposed activities
that will result in changes in water quality. Antidegradation policies can play a critical role in helping
states protect the public resource of water whose quality is better than established criteria levels and
ensure that decisions to allow reductions in water quality are made in a public manner and serve the
public good. Along with developing an antidegradation policy, each state must identify the method it will
use to implement the policy. It is important for permit writers to be familiar with their state's
antidegradation policy and how that policy is to be implemented in NPDES permits.
A state's antidegradation policy provides three levels of protection from degradation of existing water
quality:
Tier 1: This tier requires that existing uses, and the level of water quality necessary to protect the
existing uses, be maintained and protected.
Tier 2: Where the quality of waters exceeds levels necessary to support propagation offish,
shellfish, and wildlife and recreation in and on the water (sometimes referred to as high-quality
waters), Tier 2 requires that this level of water quality be maintained and protected unless the
state finds, after full satisfaction of the intergovernmental coordination and public participation
provisions of the state's continuing planning process, that allowing lower water quality is
necessary to accommodate important economic or social development in the area where the
waters are located. In allowing any such degradation or lower water quality, the state must assure
water quality adequate to protect existing uses fully and must assure that there will be achieved
the highest statutory and regulatory requirements for all new and existing point sources and all
cost-effective and reasonable best management practices for nonpoint source control.
Tier 3: This tier requires that the water quality of outstanding national resources waters
(ONRWs) be maintained and protected.
States take a variety of approaches to implementing antidegradation policies. Some states designate their
waters as Tier 1, Tier 2 (high-quality water) or Tier 3 waters in their antidegradation implementation
methods, while others designate a waterbody as a Tier 2 or high-quality water only when activities that
would degrade water quality are proposed. In some cases, states may have classified the waterbody as
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receiving a tier of protection for all pollutant-related parameters, whereas in other cases, tiers of
protection have been determined on a parameter-by-parameter basis.
6.1.1.4 General Policies (§131.13)
In addition to the three required components of water quality standards, states may, at their discretion,
include in their standards policies that generally affect how the standards are applied or implemented.
Examples of such policies include mixing zone policies, critical low flows at which criteria must be
achieved, and the availability of variances. Some general policies are discussed in more detail later in this
chapter. As with the other components of water quality standards, general policies are subject to EPA
review and approval if they are deemed to be new or revised water quality standards (i.e., if they
constitute a change to designated use(s), water quality criteria, antidegradation requirements, or any
combination).
Additional and more detailed information on water quality standards is available in the WQS Handbook.
6.1.2 Water Quality Standards Modifications
Permit writers should be aware of several types of modifications to water quality standards that could
permanently or temporarily change the standards and, thus, change the fundamental basis of WQBELs.
Those modifications, described below, are as follows:
Designated use reclassification.
Site-specific water quality criteria modification.
Water quality standard variance.
6.1.2.1 Designated Use Reclassification
Once a use has been designated for a particular waterbody or segment, that use may not be removed from
the water quality standards except under specific conditions. To remove a designated use, the state
demonstrates that attaining that use is not feasible because of any one of the six factors listed in
§ 131.10(g). The regulations at § 131.10(j) specifically require a state to conduct a UAA if the designated
uses for a waterbody do not include the uses in CWA section 101(a)(2) (i.e., fishable/swimmable uses); if
the state wishes to remove designated uses included in CWA section 101(a)(2) from its water quality
standards; or if the state wishes to adopt subcategories of CWA section 101(a)(2) uses with less stringent
criteria. The WQS Handbook discusses UAAs and removing designated uses in detail. Reclassifying a
waterbody's designated uses, as supported by a UAA, is a permanent change to both the designated use(s)
and the water quality criteria associated with that (those) use(s).
States may conduct a UAA and remove a designated use but not if it is an existing use. Existing uses are
defined in § 131.3 as those uses actually attained in the waterbody on or after November 28, 1975 (the
date of EPA's initial water quality standards regulation at 40 Federal Register 55334, November 28,
1975). At a minimum, uses are deemed attainable if they can be achieved by the implementing effluent
limits required under CWA sections 301(b) and 306 and by implementing cost effective and reasonable
best management practices (BMPs) for nonpoint source control. EPA's Water Quality Standards: UAA
Website provides additional information and some
example UAAs.
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6.1.2.2 Site-Specific Water Quality Criteria Modification
As noted above, CWA sections 303(a)-(c) require states to adopt water quality criteria sufficient to
protect applicable designated uses. In some cases, a state might find that the criteria it has adopted to
protect a waterbody or segment of a waterbody do not adequately account for site-specific conditions. In
such cases, states have the option of modifying water quality criteria on a site-specific basis. Setting site-
specific criteria might be appropriate where, for example, a state has adopted EPA's CWA section 304(a)
criteria recommendations and finds that physical or chemical properties of the water at a site affect the
bioavailability or toxicity of a chemical, or the types of local aquatic organisms differ significantly from
those actually tested in developing the EPA-recommended criteria. Site-specific criteria modifications
change water quality criteria permanently while continuing to support the current designated uses.
Development of site-specific criteria for aquatic life is discussed in section 3.7 of the WQS Handbook for
cases when (1) there might be relevant differences in the toxicity of the chemical in the water at the site
and laboratory dilution water (Water-Effect Ratio Procedure) and (2). the species at the site are more or
less sensitive than those used in developing the natural criteria (Species Recalculation Procedure). EPA's
Office of Science and Technology (OST) has developed the Interim Guidance on Determination and Use
of Water-Effect Ratios for Metals in
Appendix L of the WQS Handbook and the Streamlined Water-Effect Ratio Procedure for Discharges of
Copper2 . In addition, pages 90-97 of Appendix L provide
guidance for using the Species Recalculation Procedure. States may also consider establishing aquatic life
criteria based on natural background conditions. Further information can be found in the memo
Establishing Site Specific Aquatic Life Criteria Equal to Natural Background^
.
6.1.2.3 Water Quality Standard Variance
Water quality standard variances are changes to water quality standards and have similar substantive and
procedural requirements as what are required to remove a designated use. Unlike use removal, variances
are time-limited and do not permanently remove the current designated use of a waterbody. Variances are
usually discharger- and pollutant-specific, though some states have adopted general variances. Where a
state has adopted a general variance, the analyses necessary for the variance have been completed on a
watershed-wide or statewide basis and, therefore, the process of obtaining a variance is simplified for
individual dischargers in that watershed or state.
A variance might be appropriate where the state believes that the existing standards are ultimately
attainable and that, by retaining the existing standards rather than changing them, the state would ensure
that further progress is made in improving the water quality toward attaining the designated uses while the
variance is in effect. State-adopted variances have been approved by EPA where, among other things, the
state's standards allow variances and the state demonstrates that meeting the applicable criteria is not
feasible on the basis of one or more of the factors outlined in § 131.10(g). A variance typically is granted
for a specified period and must be reevaluated at least once every 3 years as reasonable progress is made
toward meeting the standards [see section 5.3 of the WQS Handbook and § 131.20(a)].
Modifications of water quality standards could affect effluent limitations in permits in several ways.
Specifically, the modifications can change the fundamental basis for WQBELs, potentially affecting an
assessment of the need for WQBELs and possibly resulting in either more or less stringent WQBELs than
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would otherwise be required. It is the permit writer's responsibility to ensure that any EPA-approved
modification of water quality standards is properly reflected in an affected NPDES permit.
6.1.3 Water Quality Standards Implementation
As previously noted, CWA section 301(b)(l)(C) requires NPDES permits to establish effluent limitations
as necessary to meet water quality standards. Effluent limitations and other conditions in NPDES permits
may be based on a parameter-specific approach or a WET testing approach to implementing water quality
standards. A third approach to implementing water quality standards, using biocriteria or bioassessment,
is not directly accomplished through NPDES permit effluent limitations but can lead to effluent
limitations for specific parameters or for WET. Each of those approaches to implementing water quality
standards is discussed briefly below.
What procedures should permit writers use to implement water quality standards?
The terminology used and procedures described in this manual when discussing both assessing the
need for and calculating WQBELs are based on the procedures in EPA's Technical Support Document
for Water Quality-Based Toxics Control4 (hereafter TSD). Those
procedures were developed specifically to address toxic pollutants but have been appropriately used
to address a number of conventional and nonconventional pollutants as well. Permit writers should be
aware that most permitting authorities have developed their own terminology and procedures for water
quality-based permitting, often derived from, but with variations on, EPA's guidance. For example,
EPA itself promulgated Final Water Quality Guidance for the Great Lakes System (60 FR 15387,
March 23, 1995) with minimum water quality criteria, antidegradation policies, and implementation
procedures, including permitting procedures based on the TSD. Under the CWA, Illinois, Indiana,
Michigan, Minnesota, New York, Ohio, Pennsylvania, and Wisconsin were required to adopt
procedures for the Great Lakes system that are consistent with that guidance. Permit writers should
always consult the applicable permitting regulations, policy, and guidance for the approved water
quality-based permitting procedures in their state.
6.1.3.1 Parameter-Specific Approach
The parameter-specific approach uses parameter-specific criteria for protection of aquatic life, human
health, wildlife, and sediments, as well as any other parameter-specific criteria adopted into a state's
water quality standards. The criteria are the basis for analyzing an effluent, deciding which parameters
need controls, and deriving effluent limitations that will control those parameters to the extent necessary
to achieve water quality standards in the receiving water. Parameter-specific WQBELs in NPDES permits
involve a site-specific evaluation of the discharge (or proposed discharge) and its potential effect on the
receiving water or an evaluation of the effects of multiple sources of a pollutant on the receiving water
(e.g., through a total maximum daily load [TMDL] analysis). The parameter-specific approach allows for
controlling individual parameters, (e.g., copper, BOD, total phosphorus) before a water quality impact has
occurred or for helping return water quality to a level that will meet designated uses.
6.1.3.2 Whole Effluent Toxicity (WET) Approach
WET requirements in NPDES permits protect aquatic life from the aggregate toxic effect of a mixture of
pollutants in the effluent. WET tests measure the degree of response of exposed aquatic test organisms to
an effluent. The WET approach is useful for complex effluents where it might be infeasible to identify
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and regulate all toxic pollutants in the effluent or where parameter-specific effluent limitations are set, but
the combined effects of multiple pollutants are suspected to be problematic. The WET approach allows a
permit writer to implement numeric criteria for toxicity included in a state's water quality standards or to
be protective of a narrative "no toxics in toxic amounts" criterion. Like the parameter-specific approach,
the WET approach allows permitting authorities to control toxicity in effluents before toxic impacts occur
or may be used to help return water quality to a level that will meet designated uses.
6.1.3.3 Bioassessment Approach
The biocriteria approach is used to assess the overall biological integrity of an aquatic community. As
discussed in section 6.1.1.2 above, biocriteria are numeric values or narrative statements that describe the
biological integrity of aquatic communities inhabiting waters of a given designated aquatic life use. When
incorporated into state water quality standards, biocriteria and aquatic life use designations serve as direct
endpoints for determining aquatic life use attainment. Once biocriteria are developed, the biological
condition of a waterbody can be measured through a biological assessment, or bioassessment.
A bioassessment is an evaluation of the biological condition of a waterbody using biological surveys and
other direct measurements of resident biota in surface waters. A biological survey, or biosurvey, consists
of collecting, processing, and analyzing representative portions of a resident aquatic community to
determine the community structure and function. The results of biosurveys can be compared to the
reference waterbody to determine if the biocriteria for the designated use of the waterbody are being met.
EPA issued guidance on this approach in Biological Criteria: National Program Guidance for Surface
Waters5 . As previously discussed, biocriteria generally are not
directly implemented through NPDES permits but could be used in assessing whether a waterbody is
attaining water quality standards. Nonattainment of biocriteria could lead to parameter-specific effluent
limitations where the permitting authority is able to identify specific pollutant(s) and source(s)
contributing to that nonattainment (see EPA's Biocriteria: Uses of Data - Identify Stressors to a
Waterbodv Website ) or could lead to WET limitations
where the permitting authority identifies sources of toxicity to aquatic life. EPA's Biocriteria: Uses of
Data - NPDES provides examples on the use of
bioassessment information in the NPDES permitting process.
Sections 6.2-6 A below discuss, in detail, implementing water quality standards using the parameter-
specific approach to assess the need for and develop effluent limitations in NPDES permits. Section 6.5
below provides additional detail on WET requirements in NPDES permits.
6.2 Characterize the Effluent and the Receiving Water
After identifying the most current, approved, water quality standards that apply to a waterbody, a permit
writer should characterize both the effluent discharged by the facility being permitted and the receiving
water for that discharge. The permit writer uses the information from those characterizations to determine
whether WQBELs are required (section 6.3 below) and, if so, to calculate WQBELs (section 6.4 below).
Characterizing the effluent and receiving water can be divided into five steps as shown in Exhibit 6-5 and
discussed in detail below.
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Exhibit 6-5 Steps for characterizing the effluent and receiving water
Step 1. Identify pollutants of concern in the effluent
Step 2. Determine whether water quality standards provide for consideration of a dilution
allowance or mixing zone
Step 3. Select an approach to model effluent and receiving water interactions
Step 4. Identify effluent and receiving water critical conditions
Step 5. Establish an appropriate dilution allowance or mixing zone
6.2.1 Step 1: Identify Pollutants of Concern in the Effluent
There are several sources of information for and methods of identifying pollutants of concern for
WQBEL development. For some pollutants of concern, the permit writer might not need to conduct any
further analysis and could, after characterizing the effluent and receiving water, proceed directly to
developing WQBELs (section 6.4 below). For other pollutants of concern, the permit writer uses the
information from the effluent and receiving water characterization to assess the need for WQBELs
(section 6.3 below). The following subsections identify five categories of pollutants of concern for
WQBEL development.
6.2.1.1 Pollutants with Applicable TBELs
One category of pollutants of concern includes those pollutants for which the permit writer has developed
TBELs based on national or state technology standards or on a case-by-case basis using best professional
judgment. By developing TBELs for a pollutant, the permit writer has already determined that there will
be some type of final limitations for that pollutant in the permit and must then determine whether more
stringent limitations than the applicable TBELs are needed to prevent an excursion above water quality
standards in the receiving water (see Exhibit 6-1 above). A permit writer can determine whether the
TBELs are sufficiently protective by either proceeding to calculate WQBELs as described in section 6.4
below and comparing them to the TBELs or by assuming that the maximum daily TBEL calculated is the
maximum discharge concentration in the water quality assessments described in section 6.3 below.
6.2.1.2 Pollutants with a Wasteload Allocation from a TMDL
Pollutants of concern include those pollutants for which a wasteload allocation (WLA) has been assigned
to the discharge through a TMDL. Under CWA section 303(d), states are required to develop lists of
impaired waters. Impaired waters are those that do not meet the water quality standards set for them, even
after point sources of pollution have installed the minimum required levels of pollution control
technology. The law requires that those jurisdictions establish priority rankings for waters on their CWA
section 303(d) list and develop TMDLs for those waters.
What is a WLA?
The term WLA refers to the portion of a receiving water's loading capacity that is allocated to one of its
existing or future point sources of pollution [see § 130.2(h)]. The WLA could be allocated through an
EPA-approved TMDL, an EPA or state watershed loading analysis, or a facility-specific water quality
modeling analysis.
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A TMDL is a calculation of the maximum amount of a single pollutant that a waterbody can receive and
still meet water quality standards and an allocation of that amount to the pollutant's sources. The portions
of the TMDL assigned to point sources are WLAs, and the portions assigned to nonpoint sources and
background concentrations of the pollutant are called load allocations (LAs). The calculation must
include a margin of safety to ensure that the waterbody can be used for the purposes designated in the
water quality standards, to provide for the uncertainty in predicting how well pollutant reduction will
result in meeting water quality standards, and to account for seasonal variations. A TMDL might also
include a reserve capacity to accommodate expanded or new discharges in the future. Exhibit 6-6 depicts
the parts of a TMDL.
Exhibit 6-6 Parts of a TMDL
WLAfor
Point
Source #3
WLAfor
Point
Source #1
Load Allocations (LAs)
for Nonpoint Sources
and Natural Background
TMDL = ZWLA + ZLA + Margin of Safety + Reserve Capacity
The NPDES regulations at § 122.44(d)(l)(vii)(B) require that NPDES permits include effluent limitations
developed consistent with the assumptions and requirements of any WLA that has been assigned to the
discharge as part of an approved TMDL. Thus, any pollutant for which a WLA has been assigned to the
permitted facility through a TMDL is a pollutant of concern.
Permit writers might also choose to consider any pollutant associated with an impairment of the receiving
water a pollutant of concern, regardless of whether an approved TMDL has been developed for that
pollutant, a WLA has been assigned to the permitted facility, or the permitted facility has demonstrated
that the pollutant is present in its effluent. Permitting authorities might consider monitoring requirements
to collect additional data related to the presence or absence of the impairing pollutant in a specific
discharge to provide information for further analyses.
6.2.1.3 Pollutants Identified as Needing WQBELs in the Previous Permit
Another category of pollutants of concern includes those pollutants that were identified as needing
WQBELs in the discharger's previous permit. Permit writers must determine whether the conditions
leading to a decision to include WQBELs for the pollutant in the previous permit continue to apply.
Where those conditions no longer apply, the permit writer would need to complete an anti-backsliding
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analysis to determine whether to remove the WQBELs from the reissued permit. Chapter 7 of this manual
provides additional information on anti-backsliding requirements of the CWA and NPDES regulations. In
addition, the permit writer might need to conduct an antidegradation analysis if the revised limitation
would allow degradation of the quality of the receiving water.
6.2.1.4 Pollutants Identified as Present in the Effluent through Monitoring
Pollutants of concern also include any pollutants identified as present in the effluent through effluent
monitoring. Effluent monitoring data are reported in the discharger's NPDES permit application,
discharge monitoring reports and special studies. In addition, the permitting authority might collect data
itself through compliance inspection monitoring or other special study. Permit writers can match
information on which pollutants are present in the effluent to the applicable water quality standards to
identify parameters that are candidates for WQBELs.
6.2.1.5 Pollutants Otherwise Expected to be Present in the Discharge
A final category of pollutants of concern includes those pollutants that are not in one of the other
categories but are otherwise expected to be present in the discharge. There might be pollutants for which
neither the discharger nor the permitting authority have monitoring data but, because of the raw materials
stored or used, products or by-products of the facility operation, or available data and information on
similar facilities, the permit writer has a strong basis for expecting that the pollutant could be present in
the discharge. Because there are no analytical data to verify the concentrations of these pollutants in the
effluent, the permit writer must either postpone a quantitative analysis of the need for WQBELs and
generate, or require the discharger to generate, effluent monitoring data, or base a determination of the
need for WQBELs on other information, such as the effluent characteristics of a similar discharge. A
discussion on determining the need for WQBELs without effluent monitoring data is provided in section
6.3.3 below.
6.2.2 Step 2: Determine Whether Water Quality Standards Provide for
Consideration of a Dilution Allowance or Mixing Zone
Many state water quality standards have general provisions allowing some consideration of mixing of
effluent and receiving water when determining the need for and calculating WQBELs. Depending on the
state's water quality standards and implementation policy, such a mixing consideration could be
expressed in the form of a dilution allowance or regulatory mixing zone. A dilution allowance typically is
expressed as the flow of a river or stream, or a portion thereof. A regulatory mixing zone generally is
expressed as a limited area or volume of water in any type of waterbody where initial dilution of a
discharge takes place and within which the water quality standards allow certain water quality criteria to
be exceeded. Section 6.2.5 below discusses dilution allowances and mixing zones in greater detail.
State water quality standards or implementation policies might indicate specific locations or conditions
(e.g., breeding grounds for aquatic species or bathing beaches) or water quality criteria (e.g., pathogens,
pH, bioaccumulative pollutants, or narrative criteria) for which consideration of a dilution allowance or
mixing zone is not allowed or is otherwise considered inappropriate.
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6.2.3 Step 3: Select an Approach to Model Effluent and Receiving Water
Interactions
Where consideration of a dilution allowance or mixing zone is not permitted by the water quality
standards or is not appropriate, the relevant water quality criterion must be attained at the point of
discharge. In such cases, there is no need for a water quality model to characterize the interaction between
the effluent and receiving water. In this situation effluent limitations are based on attaining water quality
criteria at the "end of the pipe."
Where a dilution allowance or mixing zone is permitted, however, characterizing the interaction between
the effluent and receiving water generally requires using a water quality model. In the majority of
situations, and in all of the examples provided in this manual, permit writers will use a steady-state water
quality model to assess the impact of a discharge on its receiving water. Steady-state means that the
model projects the impact of the effluent on the receiving water under a single or steady set of design
conditions. Because the model is run under a single set of conditions, those conditions generally are set at
critical conditions for protection of receiving water quality as discussed in section 6.2.4 below. The
permit writer would determine the amount of the dilution allowance or the size of the mixing zone that is
available under these critical conditions as provided in section 6.2.5 below.
6.2.4 Step 4: Identify Effluent and Receiving Water Critical Conditions
Where steady-state models are used for water quality-based permitting, an important part of
characterizing the effluent and receiving water is identifying the critical conditions needed as inputs to the
water quality model. Permit writers should discuss selection of critical conditions with water quality
modelers or other water quality specialists. Identifying the right critical conditions is important for
appropriately applying a water quality model to assess the need for WQBELs and to calculate WQBELs.
Some key effluent and receiving water critical conditions are summarized below.
What if I am not a water quality modeler?
Permit writers are not always water quality modelers, nor do they necessarily need to be experts in
this field. Many permitting authorities have a team of water quality specialists who model point source
discharges to provide data required for permit writers to assess the need for and develop WQBELs. In
some cases, this team might even calculate WQBELs directly for the permit writers, who then only
need to compare them to TBELs and determine the final effluent limitations for the NPDES permit.
Permit writers should, at a minimum, familiarize themselves with water quality modeling concepts
presented in this manual, particularly the identification of critical conditions input to a steady-state
water quality model, and should consult water quality modelers or other water quality specialists as
needed in the process of NPDES permit development.
6.2.4.1 Effluent Critical Conditions
In most any steady-state water quality model there will be at least two basic critical conditions related to
the effluent: flow and pollutant concentration.
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Effluent Flow
Effluent flow (designated Qd in the water quality modeling equations used in this manual) is a critical
design condition used when modeling the impact of an effluent discharge on its receiving water. A permit
writer should be able to obtain effluent flow data from discharge monitoring reports or a permit
application. Permitting authority policy or procedures might specify which flow measurement to use as
the critical effluent flow value(s) in various water quality-based permitting calculations (e.g., the
maximum daily flow reported on the permit application, the maximum of the monthly average flows from
discharge monitoring reports for the past three years, the facility design flow). Permit writers should
follow existing policy or procedures for determining critical effluent flow or, if the permitting authority
does not specify how to determine this value, look at past permitting practices and strive for consistency.
Effluent Pollutant Concentration
Permit writers can determine the critical effluent concentration of the pollutant of concern (designated Cd)
by gathering effluent data representative of the discharge. To establish the critical effluent pollutant
concentration from the available data, EPA has recommended considering a concentration that represents
something close to the maximum concentration of the pollutant that would be expected over time. In most
cases, permit writers have a limited effluent data set and, therefore, would not have a high degree of
certainty that the limited data would actually include the maximum potential effluent concentration of the
pollutant of concern. In addition, the NPDES regulations at § 122.44(d)(l)(ii) require that permit writers
consider the variability of the pollutant in the effluent when determining the need for WQBELs. To
address those concerns, EPA developed guidance for permit writers on how to characterize effluent
concentrations of certain types of pollutants using a limited data set and accounting for variability. This
guidance is detailed in EPA's TSD.
By studying effluent data for numerous facilities, EPA determined that daily pollutant measurements of
many pollutants follow a lognormal distribution. The TSD procedures allow permit writers to project a
critical effluent concentration (e.g., the 99th or 95th percentile of a lognormal distribution of effluent
concentrations) from a limited data set using statistical procedures based on the characteristics of the
lognormal distribution. These procedures use the number of available effluent data points for the
measured concentration of the pollutant and the coefficient of variation (or CV) of the data set, which is a
measure of the variability of data around the average, to predict the critical pollutant concentration in the
effluent. Exhibit 6-7 provides an example of a lognormal distribution of effluent pollutant concentrations
and projection of a critical effluent pollutant concentration (Cd). For additional details regarding EPA's
guidance, see Chapter 3 of the TSD. Many permitting authorities have developed procedures for
estimating a critical effluent pollutant concentration that are based on or derived from those procedures.
For pollutants with effluent concentrations that do not follow a lognormal distribution, permit writers
would rely on alternative procedures developed by their permitting authority for determining the critical
effluent pollutant concentration.
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Exhibit 6-7 Example of lognormal distribution of effluent pollutant concentrations and
projection of critical concentration (Cd)
a:
Concentration
(projected critical pollutant concentration
in the effluent)
6.2.4.2 Receiving Water Critical Conditions
As with the effluent, flow (for rivers and streams) and pollutant concentration are receiving water critical
conditions used in steady-state water quality models. In addition, depending on the waterbody and
pollutant of concern, there could be additional receiving water characteristics that permit writers need to
consider in a water quality model.
Receiving Water Upstream Flow
For rivers and streams, an important critical condition is the stream flow upstream of the discharge
(designated Qs). That critical condition generally is specified in the applicable water quality standards and
reflects the duration and frequency components of the water quality criterion that is being addressed. For
most pollutants and criteria, the critical flow in rivers and streams is some measure of the low flow of that
river or stream; however, the critical condition could be different (for example, a high flow, where wet
weather sources are a major problem). If a discharge is controlled so that it does not cause water quality
criteria to be exceeded in the receiving water at the critical flow condition, the discharge controls should
be protective and ensure that water quality criteria, and thus designated uses, are attained under all
receiving water flow conditions.
Examples of typical critical hydrologically based low flows found in water quality standards include the
7Q10 (7-day average, once in 10 years) low flow for chronic aquatic life criteria, the 1Q10 low flow for
acute aquatic life criteria, and the harmonic mean flow for human health criteria for toxic organic
pollutants. The permit writer might examine stream flow data from the state or the U.S. Geological
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Survey to determine the critical flow at a point upstream of the discharge. The permit writer might also
account for any additional sources of flow or diversions between the point where a critical low flow has
been calculated and the point of discharge. EPA also has developed a biologically based flow method that
directly uses the durations and frequencies specified in the water quality criteria.
Climate Change Considerations
As noted in this section, the receiving water upstream flow is an important factor in modeling the
interaction between the effluent discharge and a river or stream. In most instances, state water quality
standards or implementation policies establish the critical low flows that should be used in modeling
this interaction. The most common source of upstream flow data for water quality modelers is historical
flow gage data available through the U.S. Geological Survey. Modelers should be aware that the
effects of climate change could alter historical flow patterns in rivers and streams, making these
historical flow records less accurate in predicting current and future critical flows. Where appropriate,
water quality modelers should consider alternate approaches to establishing critical low flow conditions
that account for these climatic changes.
Receiving Water Background Pollutant Concentration
In addition to determining the critical effluent concentration of the pollutant of concern, the permit writer
also should determine the critical background concentration of the pollutant of concern in the receiving
water before the discharge (designated Cs) to ensure that any pollutant limitations derived are protective
of the designated uses. Permitting authority policies or procedures often address how to determine that
critical background concentration value for the pollutant. For example, using ambient data or working
with the discharger to obtain reliable ambient data, the permit writer might use the maximum measured
background pollutant concentration or, perhaps, an average of measured concentrations as the critical
condition. Ambient data will provide the most reliable characterization of receiving water background
pollutant concentration. EPA encourages permitting authorities to collect and use actual ambient data,
where possible. Where data are not available, however, the state might have other procedures, such as
establishing that without valid and representative ambient data, no dilution or mixing will be allowed
(i.e., criteria end-of-pipe), or using a percentage of an applicable water quality criterion or a detection,
quantitation, or other reporting level. The permit writer should consult the permitting authority's policies
and procedures or, if there are no policies or procedures available, look at past permitting practices and
maintain consistency with those practices when determining the critical receiving water background
concentrations.
Other Receiving Water Characteristics
For waterbodies other than free-flowing rivers and streams, there might be critical environmental
conditions that apply rather than flow (e.g., tidal flux, temperature). In addition, depending on the
pollutant of concern, the effects of biological activity and reaction chemistry might be important in
assessing the impact of a discharge on the receiving water. In such situations, additional critical receiving
water conditions that might be used in a steady-state water quality model include conditions such as pH,
temperature, hardness, or reaction rates, and the presence or absence of certain fish species or life stages
of aquatic organisms, to name a few.
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Sections 6.3 and 6.4 below provide further discussion of how critical conditions are applied in a water
quality model to determine the need for and calculate WQBELs.
6.2.5 Step 5: Establish an Appropriate Dilution Allowance or Mixing Zone
Following verification of whether the applicable water quality standards allow any consideration of
effluent and receiving water mixing and, for a steady-state modeling approach, the critical conditions that
apply to the effluent and receiving water, permit writers can determine how the effluent and the receiving
water mix under critical conditions. Based on this determination, permit writers can then establish the
maximum dilution allowance or mixing zone allowed by the water quality standards for each pollutant of
concern.
6.2.5.1 Type of Mixing Under Critical Conditions
On the basis of requirements in the water quality standards, the dilution allowance or mixing zone used in
water quality models and calculations are likely to vary depending on whether there is rapid and complete
mixing or incomplete mixing of the effluent and receiving water under critical conditions. Thus, the
permit writer needs to understand something about how the effluent and receiving water mix under
critical conditions.
Rapid and complete mixing is mixing that occurs when the lateral variation in the concentration of a
pollutant in the direct vicinity of the outfall is small. The applicable water quality standards might specify
certain conditions under which a permit writer could assume that rapid and complete mixing is occurring,
such as the presence of a diffuser. Some standards may also allow a demonstration of rapid and complete
mixing in cases where the conditions for simply assuming rapid and complete mixing are not met. For
example, the applicable water quality standards might specify a distance downstream of a discharge point
by which the pollutant concentration across the stream width must vary by less than a certain percentage
to assume that there is rapid and complete mixing.
If the permit writer cannot assume rapid and complete mixing and there has been no demonstration of
rapid and complete mixing, the permit writer should assume that there is incomplete mixing. Under
incomplete mix conditions, mixing occurs more slowly and higher concentrations of pollutants are present
in-stream near the discharge as compared to rapid and complete mixing. Thus, an assumption of
incomplete mixing is more conservative than an assumption of rapid and complete mixing. For
waterbodies other than rivers and streams (e.g., lakes, bays, and the open ocean) the permit writer usually
would assume incomplete mixing.
6.2.5.2 Maximum Dilution Allowance or Mixing Zone Size
Once a permit writer determines whether the applicable water quality standards allow consideration of
some ambient dilution or mixing and determines the type of mixing taking place (rapid and complete
mixing versus incomplete mixing), he or she would again consult the water quality standards to determine
the maximum size of the dilution allowance or mixing zone that may be considered in water quality
modeling calculations.
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Dilution Allowances in Rapid and Complete Mix Situations
The maximum permissible dilution allowance for rivers and streams under conditions of rapid and
complete mixing should be indicated in the water quality standards or standards implementation policy.
For example, some water quality standards allow a permit writer to use up to 100 percent of the critical
low flow of a river or stream as a dilution allowance in water quality models and calculations when there
is rapid and complete mixing. In some cases, water quality standards implement a factor of safety by
permitting only a percentage of the critical low flow to be used as a dilution allowance, even when there
is rapid and complete mixing under critical conditions. Water quality standards might incorporate such a
factor of safety to account for any uncertainty related to other conditions in the waterbody or to ensure
that some assimilative capacity is retained downstream of the discharge being permitted. Recall as well
that for some pollutants (e.g., pathogens in waters designated for primary contact recreation,
bioaccumulative pollutants), the water quality standards or implementing procedures might not authorize
any dilution allowance, even where the effluent and receiving water mix rapidly and completely.
Dilution Allowances and Regulatory Mixing Zones in Incomplete Mix Situations
In an incomplete mixing situation, the water quality standards or implementation policies might allow
some consideration of ambient dilution. Rather than permitting as much as 100 percent of the critical low
flow as a dilution allowance, however, they will likely specify either a limited dilution allowance (such as
a percentage of the critical low flow) or the maximum size of a regulatory mixing zone. A regulatory
mixing zone is a limited area or volume of water where initial dilution of a discharge takes place and
within which the water quality standards allow certain water quality criteria to be exceeded. While the
criteria may be exceeded within the mixing zone, the use and size of the mixing zone must be limited
such that the waterbody as a whole will not be impaired and such that all designated uses are maintained
as discussed in section 6.2.5.3 below. Exhibit 6-8 is a diagram illustrating the concept of a regulatory
mixing zone. The mixing zone often is a simple geometric shape inside of which a water quality criterion
may be exceeded. The geometric shape does not characterize how mixing actually occurs. Actual mixing
is described using field studies and a water quality model.
Exhibit 6-8 Regulatory mixing zones for aquatic life criteria
I,
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Note that Exhibit 6-8 above illustrates two different mixing zones, one for an acute aquatic life criterion
and one for a chronic aquatic life criterion. The water quality standards could specify different maximum
mixing zones sizes for different pollutants, different types of criteria, and different waterbody types.
Exhibit 6-9 provides examples of different maximum mixing zone sizes and dilution allowances.
Exhibit 6-9 Examples of maximum mixing zone sizes or dilution allowances under incomplete
mixing conditions by waterbody type*
; For rivers and streams:
I Mixing zones cannot be larger than 1/4 of the stream width and 1/4 mile downstream
; Mixing must be less than 1/2 stream width with a longitudinal limit of 5 times the stream width
; Dilution cannot be greater than 1/3 of the critical low flow
j For lakes and the ocean:
; Mixing zones for lakes cannot be larger than 5% of the lake surface
J A maximum of 4:1 dilution is available for lake discharges
A maximum of 10:1 dilution is available for ocean discharges
; The maximum size mixing zone for the ocean is a 100-foot radius from the point of discharge
* Examples were adapted from state standards and procedures and do not reflect EPA guidance or recommendations.
Permit writers should always check the applicable water quality standards to see if mixing zones are
permitted and determine the maximum mixing zone size for the waterbody type, pollutant of concern, and
specific criterion being considered.
6.2.5.3 on Dilution or
In addition to specifying the maximum dilution allowance or mixing zone size allowed under both rapid
and complete mixing conditions and incomplete mixing conditions, the water quality standards or
implementation policies generally include constraints that could further limit the available dilution
allowance or mixing zone size to something less than the absolute maximum allowed. For example, one
restriction on the size of the acute mixing zone could be that it must be small enough to ensure that the
potential time of exposure of aquatic organisms to a pollutant concentration above the acute criterion is
very short, and organisms passing through that acute mixing zone will not die from exposure to the
pollutant. Such a restriction might lead the permitting authority to give a discharger an acute mixing zone
for a specific pollutant that is smaller than the maximum size allowed by the water quality standards or to
not allow any acute mixing zone at all. Other possible restrictions on dilution and mixing zone size
include preventing impairment of the integrity of the waterbody as a whole and preventing significant
risks to human health. For example, a permitting authority might restrict the size of a mixing zone for a
human health criterion to prevent the mixing zone from overlapping a drinking water intake.
6.3 Determine the Need for WQBELs
After determining the applicable water quality standards and characterizing the effluent and receiving
water, a permit writer determines whether WQBELs are needed. This section provides an overview of
that process.
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6,3, f
EPA regulations at § 122.44(d)(l)(i) state, "Limitations must control all pollutants or pollutant parameters
(either conventional, nonconventional, or toxic pollutants) which the Director determines are or may be
discharged at a level that will cause, have the reasonable potential to cause, or contribute to an excursion
above any [s]tate water quality standard, including [s]tate narrative criteria for water quality." [emphasis
added] Because of that regulation, EPA and many authorized NPDES states refer to the process that a
permit writer uses to determine whether a WQBEL is required in an NPDES permit as a reasonable
potential analysis. Wording the requirements of the regulation another way, a reasonable potential
analysis is used to determine whether a discharge, alone or in combination with other sources of
pollutants to a waterbody and under a set of conditions arrived at by making a series of reasonable
assumptions, could lead to an excursion above an applicable water quality standard. The regulation also
specifies that the reasonable potential determination must apply not only to numeric criteria, but also to
narrative criteria (e.g., no toxics in toxic amounts, presence of pollutants or pollutant parameters in
amounts that would result in nuisance algal blooms). A permit writer can conduct a reasonable potential
analysis using effluent and receiving water data and modeling techniques, as described above, or using a
non-quantitative approach. Both approaches are discussed below.
6,3,2 a
When determining the need for a WQBEL, a permit writer should use any available effluent and receiving
water data as well as other information pertaining to the discharge and receiving water (e.g., type of
industry, existing TBELs, compliance history, stream surveys), as the basis for a decision. The permit
writer might already have data available from previous monitoring or he or she could decide to work with
the permittee to generate data before permit issuance or as a condition of the new permit. EPA
recommends that monitoring data be generated before effluent limitation development whenever possible.
Monitoring should begin far enough in advance of permit development to allow sufficient time to conduct
chemical analyses. Where data are generated as a condition of the permit (for example for a new
permittee), it might be appropriate for the permit writer to include a reopener condition in the permit to
allow the incorporation of a WQBEL if the monitoring data indicate that a WQBEL is required.
A reasonable potential analysis conducted with available data can be divided into four steps as shown in
Exhibit 6-10 and discussed in detail below.
Exhibit 6-10 Steps of a reasonable potential analysis with available data
Step 1. Determine the appropriate water quality model
Step 2. Determine the expected receiving water concentration under critical conditions
Step 3. Answer the question, "Is there reasonable potential?"
| Step 4. Document the reasonable potential determination in the fact sheet
6.3.2.1 Step 1; Determine the Appropriate Water Quality
Steady-state or dynamic water quality modeling techniques can be used in NPDES permitting. As
discussed in section 6.2.3 above, the examples in this manual consider only steady-state modeling
techniques, which consider the impact of a discharge on the receiving water modeled under a single set of
critical conditions.
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The specific steady-state model used will depend on the pollutant or parameter of concern and whether
there is rapid and complete mixing or incomplete mixing of the effluent and the receiving water under
critical conditions. For example, to model dissolved oxygen in a river, the permit writer might choose the
Streeter-Phelps equation. For modeling heavy metals in an incomplete mix situation, the permit writer
might choose the CORMIX model. For pollutants such as BOD, nutrients, or non-conservative
parameters, the effects of biological activity and reaction chemistry should be modeled, in addition to the
effects of dilution, to assess possible impacts on the receiving water. This manual focuses only on dilution
of a pollutant discharged to the receiving water and does not address modeling biological activity or
reaction chemistry in receiving waters. For additional information, permit writers should discuss
modeling that accounts for biological activity or reaction chemistry with water quality modelers or other
water quality specialists as needed and consult EPA's Water Quality Models and Tools Website
.
For many pollutants such as most toxic (priority) pollutants, conservative pollutants, and pollutants that
can be treated as conservative pollutants when near-field effects are of concern, if there is rapid and
complete mixing in a river or stream, the permit writer could use a simple mass-balance equation to
model the effluent and receiving water. The simple mass-balance equation as applied to a hypothetical
facility, ABC, Inc., discharging Pollutant Z to a free-flowing stream called Pristine Creek is presented in
Exhibit 6-11 below.
Exhibit 6-11 Simple mass-balance equation
Upstream
J\ABC Inc.
Downstream
Mass
where
Qs
Cs
Qd
Cd
Qr
Cr
Flow (Q)
in million gallons per day (mgd) or
cubic feet per second (cfs)
X Pollutant concentration (C)
in milligrams per liter (mg/L)
QSCS + QdCd = QrCr
stream flow in mgd or cfs above point of discharge
background in-stream pollutant concentration in mg/L
effluent flow in mgd or cfs
effluent pollutant concentration in mg/L
resultant in-stream flow, after discharge in mgd or cfs
resultant in-stream pollutant concentration in mg/L (after complete mixing occurs)
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6.3.2.2 Step 2: Determine the Expected Receiving Water Concentration under Critical
Conditions
When using a steady-state model, the permit writer, or water quality modeler, determines the impact of
the effluent discharge on the receiving water under critical conditions. This step examines how this
steady-state analysis is conducted in situations where there is incomplete mixing and then provides a
detailed discussion of this analysis for situations where there is rapid and complete mixing.
How are critical conditions defined?
When using a steady-state water quality model, permit writers generally input values that reflect critical
conditions. State permitting procedures should guide permit writers in this task. When characterizing
the effluent and receiving water for water quality-based permitting, the permit writer should follow the
permitting authority's policies and procedures for selecting the critical conditions to use in a steady-
state model. The discussion in section 6.2.4 above provides a discussion of how those values might
be selected.
Permit writers generally would input into a steady-state model for a reasonable potential analysis the
critical conditions identified in the effluent and receiving water characterization discussed in section 6.2.4
above. Recall that critical conditions include the following:
Effluent critical conditions
Flow.
- Pollutant concentration.
Receiving water critical conditions
- Flow (for rivers and streams).
- Pollutant concentration.
Other receiving water characteristics such as tidal flux, temperature, pH, or hardness
(depending on the waterbody and pollutant of concern)
As discussed in section 6.2.4.1 above, EPA and other permitting authorities have developed guidance for
determining those critical conditions. Permit writers should rely on their permit authority's policies and
procedures or past practices to determine values for all other critical conditions.
Expected Receiving Water Concentration in an Incomplete Mixing Situation
Exhibit 6-12 illustrates a situation where there is incomplete mixing of a discharge from a hypothetical
facility, Acme Co., with the receiving water, the Placid River. The concentration of the pollutant of
concern discharged by Acme Co. (Pollutant Y) is highest nearest the point of discharge and gradually
decreases until the pollutant is completely mixed with the receiving water. To determine expected
receiving water concentrations resulting from the Acme Co.'s discharge of Pollutant Y to the Placid
River, the permit writer, or water quality modeler, would use the appropriate incomplete mixing model,
calibrated to actual observations from field studies or dye studies, to simulate mixing under critical
conditions. In Step 3 below, the concentrations of the pollutant of concern in the receiving water, as
predicted by the water quality model, will be overlaid by a regulatory mixing zone established by the
applicable water quality standard to determine whether WQBELs are needed.
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Exhibit 6-12 Example of receiving water concentrations in an incomplete
mixing situation determined using an incomplete mixing water quality model
Acme Co.
Concentrations of
Pollutant Yin ug/L
Placid River
Expected Receiving Water Concentration in Rapid and Complete Mixing Situation
For many pollutants, if there is rapid and complete mixing in a river or stream, the permit writer could use
the simple mass-balance equation presented in Exhibit 6-11 above to determine the expected receiving
water concentration of the pollutant of concern under critical conditions. As noted previously, the simple
mass-balance equation is a very basic steady-state model that can be used for most toxic pollutants,
conservative pollutants, and other pollutants for which near-field effects are the primary concern. In
Exhibit 6-13, that equation is applied to ABC Inc.'s, discharge of Pollutant Z (a conservative pollutant) to
Pristine Creek under conditions of rapid and complete mixing. The mass-balance equation is rearranged
to show how it would be used in a reasonable potential analysis.
To use the simple mass-balance equation to predict receiving water impacts for a reasonable potential
analysis, the permit writer needs to input one value for each variable and solve the equation for Cr, the
downstream concentration of the pollutant. Because this model, like other steady-state models, uses a
single value for each variable, the permit writer should be sure that the values selected reflect critical
conditions for the discharge and the receiving water. In Exhibit 6-14, those critical conditions have been
identified and the equation has been solved for Cr.
It is important for permit writers to remember that, in some situations, the selected steady-state model
could be more complex than the simple mass-balance equation shown. For example, there could be other
pollutant sources along the stream segment; the pollutant might not be conservative (e.g., BOD); or the
parameter to be modeled might be affected by multiple pollutants (e.g., dissolved oxygen affected by
BOD and nutrients). For illustrative purposes, this example focuses on a situation where using a simple
mass-balance equation is sufficient (i.e., rapid and complete mixing of a conservative pollutant in a river
or stream under steady-state conditions).
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Exhibit 6-13 Mass-balance equation for reasonable potential analysis for conservative
pollutant under conditions of rapid and complete mixing
Upstream
Downstream
, Cr)
The mass-balance equation can be used to determine whether the discharge from ABC Inc., would cause,
have the reasonable potential to cause, or contribute to an excursion above the water quality standards
applicable to Pristine Creek. The equation is used to predict the concentration of Pollutant Z, a conservative
pollutant, in Pristine Creek under critical conditions. The predicted concentration can be compared to the
applicable water quality criteria for Pollutant Z. Assume the discharge mixes rapidly and completely with
Pristine Creek.
Mass
Flow (Q)
in million gallons per day (mgd)
or cubic feet per second (cfs)
X
Pollutant concentration (C)
in milligrams per liter (mg/L)
QSCS + QdCd = QrCr
where
Qs
Cs
Qd
Cd
Qr
Cr
critical stream flow in mgd or cfs above point of discharge
critical background in-stream pollutant concentration in mg/L
critical effluent flow in mgd or cfs
critical effluent pollutant concentration in mg/L
resultant in-stream flow, after discharge in mgd or cfs (Qr = Qs + Qd)
resultant in-stream pollutant concentration in mg/L (after complete mixing occurs)
Rearrange the equation to determine the concentration of Pollutant Z in the waterbody downstream of a
discharge under critical conditions:
c =(Qd)(Cd) + (Q.)(C.)
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Exhibit 6-14 Example of applying mass-balance equation to conduct reasonable potential
analysis for conservative pollutant under conditions of rapid and complete mixing
Upstream
Mass-Balance Equation: QSCS + QdCd = QrCr
Dividing both sides of the mass-balance equation by Qr gives the following:
c = (Qd)(Cd) + (Qs)(Cs)
where Cr is the receiving water concentration downstream of the discharge
The following values are known for ABC Inc. and Pristine Creek:
Qs = critical upstream flow (water quality standards allow a dilution allowance
of up to 100% of 1Q10 low flow for rapid and complete mixing)
Cs = critical upstream concentration of Pollutant Z in Pristine Creek
Qd = critical discharge flow
Cd = statistically projected critical discharge concentration of Pollutant Z
Qr = downstream flow = Qd + Qs
Acute aquatic life water quality criterion for Pollutant Z in Pristine Creek
= 1.20 cfs
= 0.75 mg/L
= 0.55 cfs
= 2.20 mg/L
= 0.55+ 1.20 = 1.75 cfs
= 1.0 mg/L
Find the projected downstream concentration (Cr) by inserting the given values into the equation as follows:
(0.55 cfs)(2.20 mg/L)+ (1.20 cfs)(0.75 mg/L)
C =-
(1.75 cfs)
Cr = 1.2 mg/L of Pollutant Z*
' calculated to 2 significant figures
6.3.2.3 Step 3: Answer the Question, Is There Reasonable Potential?
The next step in the reasonable potential analysis is to consider the results of water quality modeling to
answer the question, Is there reasonable potential?
For most pollutants, if the receiving water pollutant concentration projected by a steady-state
model (e.g., a simple mass-balance equation or a more complex model) exceeds the applicable
water quality criterion, there is reasonable potential, and the permit writer must calculate
WQBELs. (Note that for dissolved oxygen, reasonable potential would occur if the water quality
model indicates that the projected effluent concentration of the oxygen-demanding pollutants
would result in depletion of dissolved oxygen below acceptable values in the receiving water).
If the projected concentration is equal to or less than the applicable criterion, there is no
reasonable potential and, thus far, there is no demonstrated need to calculate WQBELs.
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Reasonable Potential Determination in an Incomplete Mixing Situation
To determine whether there is reasonable potential in an incomplete mixing situation, the permit writer
would compare the projected concentration of the pollutant of concern at the edge of the regulatory
mixing zone or after accounting for the available dilution allowance, with the applicable water quality
criterion. Exhibit 6-15 illustrates the reasonable potential determination for Acme Co. in a situation where
the regulatory mixing zone is described by a geometric shape. In the example, the water quality criterion
for Pollutant Y being considered is 2.0 micrograms per liter ((ig/L). The illustration shows that at many
points along the edge of the regulatory mixing zone specified by the water quality standards, which is
represented by the rectangle, the concentration of Pollutant Y exceeds 2.0 (ig/L. Therefore, there is
reasonable potential, and the permit writer must calculate WQBELs for Pollutant Y for Acme Co.
Exhibit 6-15 Reasonable potential determination in an incomplete mixing situation
k Water Quality Criterion for Pollutant Y = 2.0 ug/L
Acme Co. _---,
TTnMfik
Concentrations of Pollutant Y in ug/L
Placid River
Reasonable Potential Determination in a Rapid and Complete Mixing Situation
In the rapid and complete mixing example for ABC, Inc., shown in Exhibit 6-14 above, a projected
downstream concentration (Cr) of 1.2 mg/L of Pollutant Z was calculated. The permit writer would
compare the calculated concentration to the acute aquatic life water quality criterion of 1.0 mg/L for
Pollutant Z in Pristine Creek presented in Exhibit 6-14. Because 1.2 mg/L > 1.0 mg/L, the projected
downstream concentration exceeds the water quality criterion; therefore, there is a reasonable potential for
the water quality criterion to be exceeded, and the permit writer must calculate WQBELs for Pollutant Z.
A permit writer should repeat the reasonable potential analysis for all applicable criteria for the pollutant
of concern and must remember that the critical conditions could differ depending on the criterion being
evaluated. For example, the critical stream flow used when considering the acute aquatic life criterion
might be the 1Q10 low flow, whereas the critical stream flow used when considering the chronic aquatic
life criterion might be the 7Q10 low flow. If calculations demonstrate that the discharge of a pollutant of
concern would cause, have the reasonable potential to cause, or contribute to an excursion of any one of
the applicable criteria for that pollutant, the permit writer must develop WQBELs for that pollutant.
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In addition, it is important for permit writers to remember that they must repeat the reasonable potential
analysis for each pollutant of concern and calculate WQBELs where there is reasonable potential. For
each pollutant for which there is no reasonable potential, the permit writer should consider whether there
are any existing WQBELs in the previous permit and whether they should be retained. The permit writer
would complete an anti-backsliding analysis (see Chapter 7 of this manual) to determine whether it is
possible to remove any existing WQBELs from the reissued permit.
6.3.2.4 Step 4: Document the Reasonable Potential Determination in the Fact Sheet
As a final step, permit writers need to document the details of the reasonable potential analysis in the
NPDES permit fact sheet. The permit writer should clearly identify the information and procedures used
to determine the need for WQBELs. The goal of that documentation is to provide the NPDES permit
applicant and the public a transparent, reproducible, and defensible description of how each pollutant was
evaluated, including the basis (i.e., reasonable potential analysis) for including or not including a WQBEL
for any pollutant of concern.
6.3.3 Conducting a Reasonable Potential Analysis without Data
State implementation procedures might allow, or even require, a permit writer to determine reasonable
potential through a qualitative assessment process without using available facility-specific effluent
monitoring data or when such data are not available. For example, as noted in section 6.2.1.2 above,
where there is a pollutant with a WLA from a TMDL, a permit writer must develop WQBELs or other
permit requirements consistent with the assumptions of the TMDL. Even without a TMDL, a permitting
authority could, at its own discretion, determine that WQBELs are needed for any pollutant associated
with impairment of a waterbody. A permitting authority might also determine that WQBELs are required
for specific pollutants for all facilities that exhibit certain operational or discharge characteristics (e.g.,
WQBELs for pathogens in all permits for POTWs discharging to contact recreational waters).
Types of information that the permit writer might find useful in a qualitative approach to determining
reasonable potential include the following:
Effluent variability information such as history of compliance problems and toxic impacts.
Point and nonpoint source controls such as existing treatment technology, the type of industry,
POTW treatment system, or BMPs in place.
Species sensitivity data including in-stream data, adopted water quality criteria, or designated
uses.
Dilution information such as critical receiving water flows or mixing zones.
The permit writer should always provide justification for the decision to require WQBELs in the permit
fact sheet or statement of basis and must do so where required by federal and state regulations. A
thorough rationale is particularly important when the decision to include WQBELs is not based on an
analysis of effluent data for the pollutant of concern.
After evaluating all available information characterizing the nature of the discharge without effluent
monitoring data for the pollutant of concern, if the permit writer is not able to decide whether the
discharge causes, has the reasonable potential to cause, or contributes to an excursion above a water
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quality criterion, he or she may determine that effluent monitoring should be required to gather additional
data. The permit writer might work with the permittee to obtain data before permit issuance, if sufficient
time exists, or could require the monitoring as a condition of the newly issued or reissued permit. The
permit writer might also include a clause in the permit that would allow the permitting authority to reopen
the permit and impose an effluent limitation if the required monitoring establishes that there is reasonable
potential that the discharge will cause or contribute to an excursion above a water quality criterion.
6.4 Calculate Parameter-specific WQBELs
If a permit writer has determined that a pollutant or pollutant parameter is discharged at a level that will
cause, have reasonable potential to cause, or contribute to an excursion above any state water quality
standard, the permit writer must develop WQBELs for that pollutant parameter. This manual presents the
approach recommended by EPA's TSD for calculating WQBELs for toxic (priority) pollutants. Many
permitting authorities apply those or similar procedures to calculate WQBELs for toxic pollutants and for
a number of conventional or nonconventional pollutants with effluent concentrations that tend to follow a
lognormal distribution. Permit writers should consult permitting authority policies and procedures to
determine the methodology specific to their authorized NPDES permitting program, including the
approach for pollutants with effluent concentrations that do not follow a lognormal distribution.
6,4,1 Calculating Parameter-specific WQBELs from Aquatic Life Criteria
The TSD process for calculating WQBELs from aquatic life criteria follows five steps as shown in
Exhibit 6-16 and discussed in detail below.
Exhibit 6-16 Calculating parameter-specific WQBELs from aquatic life criteria
Step 1. Determine acute and chronic WLAs
Step 2. Calculate long-term average (LTA) concentrations for each WLA
Step 3. Select the lowest LTA as the performance basis for the permitted discharger
Step 4. Calculate an average monthly limitation (AML) and a maximum daily limitation (MDL)
Step 5. Document the calculation of WQBELs in the fact sheet.
6.4.1.1 Step 1: Determine Acute and Chronic WLAs
Before calculating a WQBEL, the permit writer will first need to determine the appropriate WLAs for the
point source discharge based on both the acute and chronic criteria. A WLA may be determined from a
TMDL or calculated for an individual point source directly. Where an EPA-approved TMDL has been
developed for a particular pollutant, the WLA for a specific point source discharger is the portion of that
TMDL that is allocated to that point source, as discussed in section 6.2.1.2 above. Where no TMDL is
available, a water quality model generally is used to calculate a WLA for the specific point source
discharger. The WLA is the loading or concentration of pollutant that the specific point source may
discharge while still allowing the water quality criterion to be attained downstream of that discharge. Of
course, the WLA calculation should take into account any reserve capacity, safety factor, and
contributions from other point and nonpoint sources as might be required by the applicable water quality
standards regulations or implementation policies.
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When a WLA is not given as part of a TMDL or where a separate WLA is needed to address the near-
field effects of a discharge on water quality criteria, permit writers will, in many situations, use a steady-
state water quality model to determine the appropriate WLA for a discharge. As discussed in section 6.3
above, steady-state models generally are run under a single set of critical conditions for protection of
receiving water quality. If a permit writer uses a steady-state model with a specific set of critical
conditions to assess reasonable potential, he or she generally may use the same model and critical
conditions to calculate a WLA for the same discharge and pollutant of concern.
As with the reasonable potential assessment, the type of steady-state model used to determine a WLA
depends on the type of mixing that occurs in the receiving water and the type of pollutant or parameter
being modeled. As discussed in section 6.3.2 above, permit writers can use the mass-balance equation as a
simple steady-state model for many pollutants, such as most toxic (priority) pollutants or any pollutant
that can be treated as a conservative pollutant when considering near-field effects, if there is rapid and
complete mixing in the receiving water. For pollutants or discharge situations that do not have those
characteristics (e.g., non-conservative pollutants, concern about effects on a downstream waterbody), a
water quality model other than the mass-balance equation would likely be more appropriate.
The mass-balance equation is presented again in Exhibit 6-17. In the exhibit, the equation is rearranged to
show how it would be used to calculate a WLA for a conservative pollutant discharged to a river or
stream under conditions of rapid and complete mixing.
6.4.1.2 Step 2: Calculate LTA Concentrations for Each WLA
The requirements of a WLA generally must be interpreted in some way to be expressed as an effluent
limitation. The goal of the permit writer is to derive effluent limitations that are enforceable, adequately
account for effluent variability, consider available receiving water dilution, protect against acute and
chronic impacts, account for compliance monitoring sampling frequency, and assure attainment of the
WLA and water quality standards. In developing WQBELs, the permit writer develops limitations that
require a facility to perform in such a way that the concentration of the pollutant of concern in the effluent
discharged is nearly always below the WLA.
To accomplish that goal, EPA has developed a statistical permit limitation derivation procedure to
translate WLAs into effluent limitations for pollutants with effluent concentration measurements that tend
to follow a lognormal distribution. EPA believes that this procedure, discussed in Chapter 5 of the TSD,
results in defensible, enforceable, and protective WQBELs for such pollutants. In addition, a number of
states have adopted procedures based on, but not identical to, EPA's guidance that also provide
defensible, enforceable, and protective WQBELs. Permit writers should always use the procedures
adopted by their permitting authority. In addition, permit writers should recognize that alternative
procedures would be used to calculate effluent limitations for pollutants with effluent concentrations that
cannot generally be described using a lognormal distribution.
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Exhibit 6-17 Example of applying mass-balance equation to calculate WLAs for conservative
pollutant under conditions of rapid and complete mixing
Upstream
Downstream
, Cr)
where
Qs
Cs
Qd
Cd
Qr
Cr
Mass Balance Equation: QSCS + QdCd = Q,Cr
background stream flow in mgd or cfs above point of discharge
background in-stream pollutant concentration in mg/L
effluent flow in mgd or cfs
effluent pollutant concentration in mg/L = WLA
resultant in-stream flow, after discharge in mgd or cfs
resultant in-stream pollutant concentration in mg/L (after complete mixing occurs)
Rearrange the equation to determine the WLA (Cd) for ABC Inc., necessary to achieve the acute water quality
criterion for Pollutant Z in Pristine Creek (Cr) downstream of the discharge:
c _QA-Q.C.
-
The following values are known for ABC Inc., and Pristine Creek:
Qs = critical upstream flow (water quality standards allow a dilution allowance
of up to 100% of 1Q10 low flow for rapid and complete mixing) = 1.20 cfs
Cs = upstream concentration of Pollutant Z in Pristine Creek = 0.75 mg/L
Qd =discharge flow = 0.55 cfs
Qr = downstream flow = Qd + Qs = 0.55 + 1 .20 = 1 .75 cfs
Cr = acute water quality criterion for Pollutant Z in Pristine Creek =1.0 mg/L
Determine the WLA for ABC Inc., by inserting the given values into the equation as follows:
WLA for ABC Inc. = Cd = 0-75 cfs)(1.0 mg/L) -(1.20 cfs)(0.75 mg/L)
(0.55 cfs)
Cd = 1 .5 mg/L of Pollutant Z*
* calculated to 2 significant figures
For those pollutants with effluent concentrations that do follow a lognormal distribution, the distribution
can be described by determining a long-term average (or LTA) that ensures that the effluent pollutant
concentration remains nearly always below the WLA and by the CV, a measure of the variability of data
around the LTA. Exhibit 6-18 illustrates a lognormal distribution with the LTA, CV, and WLA highlighted.
When applying aquatic life criteria, a permit writer generally establishes a WLA based on the acute aquatic
life criterion and a WLA based on the chronic aquatic life criterion. Thus, the permit writer determines two
LTAsone that would ensure that an effluent concentration is nearly always below the acute WLA and one
that would ensure that an effluent concentration nearly always below the chronic WLA. Each LTA, acute
and chronic, would represent a different performance expectation for the discharger.
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Exhibit 6-18 Example of lognormal distribution of effluent pollutant concentrations and
calculation of LTA
o
c
0)
3
cr
0)
1
0)
01
LTA
WLA
Concentration
6.4.1.3
Step 3: Select the Lowest LTA as the Performance Basis for the Permitted
Discharger
EPA recommends that WQBELs be based on a single performance expectation for a facility; therefore,
once a permit writer has calculated LTA values for each WLA, he or she would select only one of those
LTAs to define the required performance of the facility and serve as the basis for WQBELs. Because
WQBELs must assure attainment of all applicable water quality criteria, the permit writer would select
the lowest LTA as the basis for calculating effluent limitations. Selecting the lowest LTA would ensure
that the facility's effluent pollutant concentration remains below all the calculated WLAs nearly all the
time. Further, because WLAs are calculated using critical receiving water conditions, the limiting LTA
would also ensure that water quality criteria are fully protected under nearly all conditions.
6.4.1.4 Step 4: Calculate an Average Monthly Limitation (AML) and a Maximum Daily
Limitation (MDL)
The NPDES regulations at § 122.45(d) require that all effluent limitations be expressed, unless
impracticable, as both AMLs and MDLs for all discharges other than POTWs and as both AMLs and
average weekly limitations (AWLs) for POTWs. The AML is the highest allowable value for the average
of daily discharges over a calendar month. The MDL is the highest allowable daily discharge measured
during a calendar day or 24-hour period representing a calendar day. The AWL is the highest allowable
value for the average of daily discharges over a calendar week. For pollutants with limitations expressed
in units of mass, the daily discharge is the total mass discharged over the day. For limitations expressed in
other units, the daily discharge is the average measurement of the pollutant over the period of a day.
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In the TSD, EPA recommends establishing an MDL, rather than an AWL, for discharges of toxic
pollutants from POTWs. That approach is appropriate for at least two reasons. First, the basis for the
AWL for POTWs is the secondary treatment requirements discussed in section 5.1.1.1 of this manual and
is not related to the need for assuring attainment of water quality standards. Second, an AWL, which
could be the average of up to seven daily discharges, could average out peak toxic concentrations and,
therefore, the discharge's potential for causing acute toxic effects might be missed. An MDL would be
more likely to identify potential acutely toxic impacts.
Chapter 5 of the TSD includes statistical tools for calculating MDLs and AMLs from the LTA value
selected in Step 3 above. Again, note that those procedures apply to pollutants with effluent concentration
measurements that tend to follow a lognormal distribution. EPA has not developed guidance on
procedures for calculating effluent limitations for pollutants with effluent concentrations that generally
cannot be described using a lognormal distribution. For such pollutants, permit writers should use other
procedures as recommended by their permitting authority in its policies, procedures, or guidance.
Whether using the TSD procedures or other procedures for calculating WQBELs, the objective is to
establish limitations calculated to require treatment plant performance levels that, after considering
acceptable effluent variability, would have a very low statistical probability of exceeding the WLA and,
therefore, would comply with the applicable water quality standards under most foreseeable conditions.
6.4.1.5 Step 5: Document Calculation of WQBELs in the Fact Sheet
Permit writers should document in the NPDES permit fact sheet the process used to develop WQBELs.
The permit writer should clearly identify the data and information used to determine the applicable water
quality standards and how that information, or any applicable TMDL, was used to derive WQBELs and
explain how the state's antidegradation policy was applied as part of the process. The information in the
fact sheet should provide the NPDES permit applicant and the public a transparent, reproducible, and
defensible description of how the permit writer properly derived WQBELs for the NPDES permit.
6.4.2 Calculating Chemical-specific WQBELs based on Human Health
Criteria for Toxic Pollutants
Developing WQBELs for toxic pollutants affecting human health is somewhat different from calculating
WQBELs for other pollutants because (1) the exposure period of concern is generally longer (e.g., often a
lifetime exposure) and (2) usually the average exposure, rather than the maximum exposure, is of
concern. EPA's recommended approach for setting WQBELs for toxic pollutants for human health
protection is to set the AML equal to the WLA calculated from the human health toxic pollutant criterion
and calculate the MDL from the AML. Section 5.4.4 of the TSD describes statistical procedures used for
such calculations for pollutants with effluent concentrations that follow a lognormal distribution. Once
again, for pollutants with effluent concentrations that do not follow a lognormal distribution, permit
writers should use other procedures as specified by their permitting authority.
If the permit writer calculates chemical-specific WQBELs from human health criteria, he or she should
compare the limitations to any other calculated WQBELs (e.g., WQBELs based on aquatic life criteria)
and TBELs and apply antidegradation and anti-backsliding requirements to determine the final limitations
that meet all technology and water quality standards. As discussed above, that process should be
documented in the fact sheet for the NPDES permit.
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6.5 Calculate Reasonable Potential and WQBELs for WET
WET tests measure the degree of response of exposed aquatic test organisms to an effluent mixed in some
proportion with control water (e.g., laboratory water or a non-toxic receiving water sample). WET testing
is used as a second approach, in addition to the chemical-specific approach, to implementing water
quality standards in NPDES permits. This section provides a brief introduction to WET testing and WET
limitations.
Test of Significant Toxicity (1ST)
At the time of the writing of this guidance manual, EPA had recently published a new statistical
approach that assesses the whole effluent toxicity (WET) measurement of wastewater effects on
specific test organisms' ability to survive, grow, and reproduce. This new approach is called the Test of
Significant Toxicity (TST) and is a statistical method that uses hypothesis testing techniques based on
research and peer-reviewed publications. The hypothesis test under the TST approach examines
whether an effluent, at the critical concentration (e.g., in-stream waste concentration [IWC]), and the
control within a WET test differ by an unacceptable amount (the amount that would have a measured
detrimental effect on the ability of aquatic organisms to thrive and survive). The TST implementation
document and the TST technical document are available at the NPDES WET Website
.
6.5.1 Types of WET Tests
In many WET tests, the effluent and control water are mixed in varying proportions to create a dilution
series. Exhibit 6-19 is an example of a typical dilution series used in WET testing.
Exhibit 6-19 Example of typical dilution series
50 75 87.5 93.75 100 Percent Dilution Water
u _
100
50
25
12.5
6.25
0 Percent Effluent
There are two types of WET tests: acute and chronic. An acute toxicity test usually is conducted over a
short time, generally 96 hours or less, and the endpoint measured is mortality. The endpoint for an acute
test is often expressed as an LC50 (i.e., the percent of effluent that is lethal to 50 percent of the exposed
test organisms). A chronic toxicity test is usually conducted during a critical life phase of the organism
and the endpoints measured are mortality and sub-lethal effects, such as changes in reproduction and
growth. A chronic test can occur over a matter of hours or days, depending on the species tested and test
endpoint. The endpoint of a chronic toxicity test often is expressed in one of the following ways:
No observed effect concentration (NOEC), the highest concentration of effluent (i.e., highest
percent effluent) at which no adverse effects are observed on the aquatic test organisms.
Lowest observed effect concentration (LOEC), the lowest concentration of effluent that causes
observable adverse effects in exposed test organisms.
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Inhibition concentration (1C), a point estimate of the effluent concentration that would cause a
given percent reduction in a biological measurement of the test organisms.
Effect concentration (EC), a point estimate of the effluent concentration that would cause an
observable adverse effect in a given percentage of test organisms.
For additional information on WET monitoring and WET test methods, see section 8.2.4 of this manual.
or
There are two options for expressing WET limitations or test results. First, WET limitations or test results
can be expressed directly in terms of the WET test endpoints discussed above (e.g., LC50, NOEC, and
IC2s). Alternatively, the limitations or test results can be expressed in terms of toxic units (TUs). A TU is
the inverse of the sample fraction, calculated as 100 divided by the percent effluent. Exhibit 6-20 presents
example TUs for expressing acute and chronic test results.
Exhibit 6-20 Example of toxic units
If an acute test result is a LCso of 60 percent, that result can be expressed as
= 1.7 acute toxic units = 1.7 TUa
60
If a chronic test result is an IC25 of 40 percent effluent, that result can be expressed as
100
40
= 2.5 chronic toxic units = 2.5 TUc
It is important to distinguish acute TUs (TUa) from chronic TUs (TUC). The difference between TUa and
TUC can be likened to the difference between miles and kilometers. Both miles and kilometers are used to
measure distance, but a distance of 1.0 mile is not the same as a distance of 1.0 kilometer. Likewise, both
TUa and TUC are expressions of the toxicity of an effluent, but 1.0 TUa is not the same as 1.0 TUC. It is
possible, however, to determine the relationship between the acute toxicity of an effluent and the chronic
toxicity of that same effluent, just as it is possible to determine the relationship between miles and
kilometers (i.e., through a conversion factor). Unlike the conversion between miles and kilometers that
remains constant, the conversion factor between acute and chronic toxic units varies from effluent to
effluent.
For an effluent, the permit writer could develop a conversion factor that would allow conversion of TUa
into equivalent TUC or vice versa. This conversion factor is known as an acute-to-chronic ratio (ACR) for
that effluent. The ACR for an effluent may be calculated where there are at least 10 sets of paired acute
and chronic WET test data available. The ACR is determined by calculating the mean of the individual
ACRs for each pair of acute and chronic WET tests. Where there are not sufficient data to calculate an
ACR for an effluent (i.e., less than 10 paired sets of acute and chronic WET test data), EPA recommends
a default value of ACR = 10. Exhibit 6-21 presents examples showing how the ACR converts TUa into
TUC, how to calculate an ACR from existing data, and how, once an ACR is calculated, a permit writer
could estimate the chronic toxicity of an effluent sample from its measured acute toxicity or vice versa.
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Exhibit 6-21 Using the ACR
The ACR is expressed
Acute Endpoint
ACR =
Chronic Endpoint 1C
25
A TU is the inverse of the sample fraction.
Therefore, by definition
TUa =
100
TUc==
100
Consequently, toxicity as percent sample,
may be expressed
ir 10° ir 10°
LCso = 1C,. =
TUa TUc
Substituting into the original equation gives
100
LCK
ACR =
'50
TUa _ TUc
1C
25
100 TUa
TUc
Example 1
Given: LC50 = 28%, IC25 = 10%
LC50 _ 28%
1C,. ~ 10%
= 2.8
Example 3
Given: Toxicity data for a facility's effluent
for C. dubia. as presented in the
table to the right.
The ACR in the third column is calculated
using the following equation:
IC25
Example 4
Given: TUa = 1.8, ACR = 3. 5
ACR
Estimated TUC
TUc
'TLU
Example 2
Given: TUa = 3.6, TUC =10.0
_ TUc 10.0
TUa 3.6
LC50
(% effluent)
62
18
68
61
63
70
17
35
35
35
47
IC25
(% effluent)
10
10
25
10
25
25
5
10
10
25
10
Mean
TUc = ACR x TUa
_OC y 1 STUa fi^TU-
TUa
ACR
6.2
1.8
2.7
6.1
2.5
2.8
3.4
3.5
3.5
1.4
4.7
3.5
flie for
If a state has numeric criteria for WET, a permit writer could use the results of WET tests to project acute
or chronic toxicity in the receiving water after accounting for the applicable dilution allowance or mixing
zone made available in the water quality standards. The permit writer would compare the projected
toxicity of the receiving water to the applicable water quality criterion for WET. If the projected toxicity
exceeds the applicable numeric water quality criterion for WET, the discharge would cause, have the
reasonable potential to cause, or contribute to an excursion above the applicable water quality standards,
and the permit writer must develop a WQBEL for WET [see § 122.44(d)(l)(iv)]. In that way, numeric
criteria for WET can be treated similarly to chemical-specific criteria. Exhibit 6-22 provides an example
of how the mass-balance equation is used to conduct a reasonable potential analysis for WET.
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Exhibit 6-22 Example of mass-balance equation for a WET reasonable potential analysis
Upstream
Downstream
The mass-balance equation can be used to determine whether the discharge from ABC Inc. would cause, have
the reasonable potential to cause, or contribute to toxicity in Pristine Creek that exceeds the numeric water quality
criteria for acute or chronic toxicity. Assume the discharge mixes rapidly and completely with Pristine Creek.
Mass-Balance Equation: QSCS + QdCd = QrCr
Dividing both sides of the mass-balance equation by Qr gives the following:
^ (Qd)(Cd) + (Qs)(Cs)
The following values are known for ABC Inc. and Pristine Creek:
Qs = Critical upstream flow (1Q10 for acute protection) = 23.6 cfs
(7Q10 for chronic protection) = 70.9 cfs
Cs = Upstream toxicity in Pristine Creek (acute) = 0 TUa
(chronic) = 0 TUC
Qd = Discharge flow = 7.06 cfs
Cd = Discharge toxicity (acute) = 2.50 TUa
(chronic) = 8.00 TUC
Qr = Downstream flow = Qd + Qs
Acute Water Quality Criterion in Pristine Creek = 0.3 TUa
Chronic Water Quality Criterion in Pristine Creek =1.0 TUC
Find the downstream concentration (Cr) by inserting the given values into the equation as follows:
For acute toxicity:
= (7.06 cfs)(2.5 TUa) + (23.6 cfs)(0 TUa) =
7.06 cfs + 23.6 cfs
The downstream concentration (Cr) exceeds the water quality criterion for acute toxicity of 0.3 TUa.
For chronic toxicity:
r (7.06 cfs)(8.00 TUc) + (70.9 cfs)(0 TUc) n70T||
U. = - = U./Z I Uc
7.06 cfs + 70. 9 cfs
The downstream concentration (Cr) does not exceed the water quality criterion for chronic toxicity of 1.0 TUC.
In Exhibit 6-22 above, the downstream concentration under critical conditions for the acute water quality
criterion (Cr = 0.58 TUa) exceeds the water quality criterion for acute toxicity (0.3 TUa); therefore there is
reasonable potential and WET limitations are required. WET limitations would be calculated in much the
same way as limitations on specific chemicals. The limitations would be calculated to ensure that WET
criteria are not exceeded after any available dilution or at the edge of the applicable mixing zone.
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Where state water quality standards do not include numeric criteria for WET, a permit writer could
evaluate the need for WQBELs for WET on the basis of narrative criteria; specifically, a narrative
criterion stating that waterbodies must be free from toxics in toxic amounts. To make it easier for a permit
writer to readily establish WET limitations in this situation, the permitting authority should have a policy
for implementing the narrative criterion. Following the permitting authority's policy, if the permit writer
determines that a discharge causes, has the reasonable potential to cause, or contributes to an in-stream
excursion above a narrative criterion, the regulations at § 122.44(d)(l)(v) require that the permit include
WQBELs for WET unless the permit writer demonstrates that parameter-specific limitations for the
effluent are sufficient to attain and maintain applicable numeric and narrative water quality criteria. In
other words, the permit must include WET limitations unless the permit writer is able to determine the
specific pollutants that are the source of toxicity and include parameter-specific limitations for those
pollutants that assure, and will continue to assure, attainment of water quality standards. If there are no
criteria in the state water quality standards for the specific parameters causing the toxicity, the permit
writer can establish WQBELs using one of three approaches outlined in § 122.44(d)(l)(vi):
Use EPA's national recommended criteria.
Calculate a numeric criterion that will attain and maintain the applicable narrative criterion.
Control the pollutant using an indicator parameter for the pollutant of concern.
A permit also could include a requirement to conduct a toxicity identification evaluation and toxicity
reduction evaluation (TIE/TRE) as a special condition in an NPDES permit. (Chapter 9 of this manual
presents more information on special conditions.) A TIE/TRE is a site-specific study designed to
systematically investigate and identify the causes of effluent toxicity problems, isolate the sources of that
toxicity, identify and implement appropriate toxicity control options, and confirm the effectiveness of
those control options and the reduction in toxicity. The permit writer might require a TIE/TRE when
WET limitations are exceeded or, if there are no WET limitations in the permit, where WET testing
demonstrates an unacceptable level of effluent toxicity. Because WET testing indicates the degree of
toxicity of an effluent, but does not specifically identify the cause of that toxicity or ways to reduce
toxicity, a TIE/TRE is necessary to achieve compliance with effluent limitations or other effluent toxicity
requirements in NPDES permits. If a TIE/TRE is not required through the special conditions section of
the permit, it could be required via a CWA section 308 letter, a CWA section 309 administrative order, or
a consent decree.
6.6 Antidegradation Review
Early in the permit development process, a permit writer should check the state's antidegradation policy
and implementation methods to determine what tier(s) of protection, if any, the state has assigned to the
proposed receiving water for the parameter(s) of concern. The regulations concerning antidegradation and
each of the tiers are described above in section 6.1.1.3. The tier of antidegradation protection is important
for determining the required process for developing the water quality-based permit limits and conditions.
In some cases, where a waterbody is classified as Tier 3 for antidegradation purposes, the permit writer
might find that it is not possible to issue a permit for the proposed activity.
If the state has not specified the tier, the permit writer will need to evaluate, in accordance with the state's
implementation procedures, whether the receiving waterbody is of high water quality for the parameters
of concern, and thus will require Tier 2 protection. After identifying the tier(s) of protection for the
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proposed receiving waterbody and parameter(s) of concern, the permit writer should consult the state's
antidegradation implementation procedures re levant to the tier(s).
The following sections provide methods permit writers should consider for implementing, through the
WQBEL development process, the three levels of protection typically found in a state's antidegradation
policy. Implementation of the state's antidegradation policy could have a significant effect on the
calculation of WQBELs.
6.6.1 Tier 11mplementation
All waterbodies receive at least Tier 1 protection. Tier 1 protection means that the permit writer must
include limits in the permit sufficient to maintain and protect water quality necessary to protect existing
uses. In practice, for a Tier 1 receiving waterbody, the permit writer typically calculates the WQBELs on
the basis of the applicable criteria because the state's designated uses and criteria to protect those uses
must be sufficient to protect the existing uses. If a Tier 1 waterbody is impaired for a parameter that
would be present in the proposed discharge, the permit writer should identify and consult any relevant
TMDLs to determine what quantity of pollutant (if any) is appropriate.
6.6.2 Tier 2 Implementation
For new or increased discharges that could potentially lower water quality in high-quality waters, Tier 2
protection provides the state with a framework for making decisions regarding the degree to which it will
protect and maintain the high water quality. A new or expanded discharge permit application typically
triggers a Tier 2 antidegradation review. Depending on the outcome of the review, the permit could be
written to maintain the existing high water quality or could be written to allow some degradation.
Each state's antidegradation policy or implementation procedures should describe the Tier 2
antidegradation review process. Though the process varies among states, EPA's antidegradation
regulation at § 131.12 outlines the common elements of the process. To permit a new or increased
discharge that would lower water quality, the state is required to make a finding on the basis of the
following:
The state must find that allowing lower water quality is necessary for important social or
economic development in the area in which the waters are located.
- The state would perform an alternatives analysis to evaluate whether the proposed discharge
is actually necessary (i.e., whether there are less degrading feasible alternatives) and that
might include consideration of a wide range of alternatives (e.g. non-discharging options,
relocation of discharge, alternative processes, and innovative treatments).
The state should provide a justification of important social or economic development (or
both) that would occur as a result of permitting the proposed discharge.
The state's finding must be made after full satisfaction of its own intergovernmental coordination
and public participation provisions.
The state must assure that the highest statutory and regulatory requirements for all new and
existing point sources will be achieved.
The state must assure that all cost-effective and reasonable BMPs for nonpoint source control will
be achieved.
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The state must assure that water quality will still protect existing uses.
If, after fulfilling the above conditions of the Tier 2 antidegradation review process, the state makes a
determination to allow a new or increased discharge that would lower water quality, the permit writer
may include such limitations in the NPDES permit for that discharge provided the limitations meet all
other applicable technology and water quality standards.
6.6.3 Tier 3 Implementation
States identify their own ONRWs for Tier 3 protection, which requires that the water quality be
maintained and protected. This is the most stringent level of protection. ONRWs often include waters in
national or state parks, wildlife refuges, and waters of exceptional recreational or ecological significance.
Waterbodies can be given Tier 3 protection regardless of their existing level of water quality. Some states
implement Tier 3 by prohibiting any new or increased discharges to ONRWs or their tributaries that
would result in lower water quality, with the exception of some limited activities such as those that would
result in temporary changes in water quality ultimately resulting in restoration. Some states allow
increased discharges as long as they are offset by equivalent or greater reductions elsewhere in the
waterbody.
In addition to Tiers 1, 2, and 3, some states have a class of waters considered outstanding to the state and
for which the state might have specific antidegradation requirements. Such waterbodies are sometimes
referred to as Tier 2 'A waters because implementation of the antidegradation policy for them affords a
greater degree of protection than Tier 2 but more flexibility than Tier 3.
Chapter 4 of EPA's WQS Handbook and the Water Quality Standards Regulation Advance Notice of
Proposed Rulemaking (64 FR 36742, July 7, 1998) include additional information on implementing
antidegradation policies. The permit writer should clearly explain the antidegradation analysis and how it
affects calculation of WQBELs in the fact sheet or statement of basis for the permit.
1 U.S. Environmental Protection Agency. 1994. Water Quality Standards Handbook: Second Edition (WQS Handbook).
EPA 823-B-94-005a. U.S. Environmental Protection Agency, Office of Water, Washington DC.
.
2 U.S. Environmental Protection Agency. 2001. Streamlined Water-Effect Ratio Procedure for Discharges of Copper.
EPA-822-R-01-005. U.S. Environmental Protection Agency, Office of Science and Technology, Washington, DC.
.
3 Davies, Tudor T. 1997. Establishing Site Specific Aquatic Life Criteria Equal to Natural Background. U.S. Environmental
Protection Agency, Office of Science and Technology, Washington, DC.
.
4 U.S. Environmental Protection Agency. 1991. Technical Support Document for Water Quality-Based Toxics Control (TSD).
EPA-505/2-90-001. U.S. Environmental Protection Agency, Office of Water, Washington, DC.
.
5 U.S. Environmental Protection Agency. 1990. Biological Criteria: National Program Guidance for Surface Waters.
EPA-440/5-91-004. U.S. Environmental Protection Agency, Office of Science and Technology, Washington, DC.
.
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CHAPTER 7. Final Effluent Limitations and
Anti-backsliding
As illustrated in Exhibit 7.1, after calculating applicable technology-based effluent limitations (TBELs)
and water quality-based effluent limitations (WQBELs), the permit writer must determine the final
effluent limitations that will be included in the National Pollutant Discharge Elimination System
(NPDES) permit for each pollutant or pollutant parameter. For reissued permits, that determination must
also include an assessment of whether the revised effluent limitations are consistent with the Clean Water
Act (CWA) requirements and NPDES regulations related to anti-backsliding.
Exhibit 7-1 Developing effluent limitations
Develop technology-based effluent limitations
(TBELs)
Chapter 5
Develop water quality-based effluent
limitations (WQBELs)
Chapter 6
Determine final effluent limitations that meet
technology and water quality standards and
anti-backsliding requirements
Chapter 7
7.1 Determining Final Effluent Limitations
When determining the final effluent limitations, the permit writer must ensure that all applicable statutory
and regulatory requirements, including technology and water quality standards, are fully implemented.
The permit writer determines the calculated limitations (TBELs, WQBELs, or some combination
of the calculated limitations) that will ensure that all applicable CWA standards are met.
As noted above, for reissued permits, if any of the limitations are less stringent than limitations on
the same pollutant in the previous NPDES permit, the permit writer then conducts an anti-
backsliding analysis and, if necessary, revises the limitations accordingly. A detailed discussion
of the anti-backsliding provisions of the CWA and the NPDES regulations is included below in
Section 7.2.
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In addition, the permit writer should clearly explain in the fact sheet for the permit how the final
limitations in the permit were determined and how those limitations meet both technology and water
quality standards (including antidegradation) and, where appropriate, how an anti-backsliding analysis
was applied to the final effluent limitations.
7.2 Applying Anti-backsliding Requirements
As noted in Section 7.1, after selecting the calculated effluent limitations for a pollutant that ensure that
all CWA standards are met, the permit writer applies anti-backsliding requirements, as necessary, to
determine the final effluent limitations. In general, the term anti-backsliding refers to statutory and
regulatory provisions that prohibit the renewal, reissuance, or modification of an existing NPDES permit
that contains effluent limitations, permit conditions, or standards less stringent than those established in
the previous permit. There are, however, exceptions to the prohibition, and determining the applicability
and circumstances of the exceptions requires familiarity with both the statutory and regulatory provisions
that address anti-backsliding.
7.2.1 Anti-backsliding Statutory Provisions
Clean Water Act (CWA) section 402(o) expressly prohibits backsliding from certain existing effluent
limitations. CWA section 402(o) consists of three main parts: (1) a prohibition on specific forms of
backsliding, (2) exceptions to the prohibition, and (3) a safety clause that provides an absolute limitation
on backsliding.
7.2.1.1 Statutory Prohibition Against Backsliding
First, CWA section 402(o)(l) prohibits the relaxation of effluent limitations for two situations:
To revise an existing TBEL that was developed on a case-by-case basis using best professional
judgment (BPJ) to reflect subsequently promulgated effluent limitations guidelines and standards
(effluent guidelines) that would result in a less stringent effluent limitation.
Relaxation of an effluent limitation that is based on state standards, such as water quality
standards or treatment standards, unless the change is consistent with CWA section 303(d)(4).
Section 303(d)(4) may be applied independently of section 402(o).
The prohibition against relaxation of effluent limitations is subject to the exceptions in CWA section
402(o)(2) and, for limitations based on state standards, the provisions of CWA section 303(d)(4). Those
exceptions are outlined further in the following sections.
7.2.1.2 Exceptions for Case-by-Case TBELs
CWA section 402(o)(2) outlines specific exceptions to the general prohibition against revising an existing
TBEL that was developed on a case-by-case basis using BPJ to reflect subsequently promulgated, less
stringent effluent guidelines in a renewed, reissued, or modified permit. CWA section 402(o)(2) provides
that relaxed limitations may be allowed where
There have been material and substantial alternations or additions to the permitted facility that
justify the relaxation.
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New information (other than revised regulations, guidance, or test methods) is available that was
not available at the time of permit issuance and that would have justified a less stringent effluent
limitation. If the effluent limitation was based on water quality standards, any changes must result
in a decrease in pollutants discharged.
Technical mistakes or mistaken interpretations of the law were made in issuing the permit under
CWA section 402(a)(l)(b).
Good cause exists because of events beyond the permittee's control (e.g., natural disasters) and
for which there is no reasonably available remedy.
The permit has been modified under CWA sections 301(c), 301(g), 301(h), 310(i), 301(k),
301(n), or316(a).
The permittee has installed and properly operated and maintained required treatment facilities but
still has been unable to meet the effluent limitations (relaxation may be allowed only to the
treatment levels actually achieved).
7.2.1.3 Exceptions for Limitations Based on State Standards
EPA has consistently interpreted CWA section 402(o)(l) to allow relaxation of WQBELs and effluent
limitations based on state standards if the relaxation is consistent with the provisions of CWA section
303(d)(4) or if one of the exceptions in CWA section 402(o)(2) is met. The two provisions constitute
independent exceptions to the prohibition against relaxation of effluent limitations. If either is met,
relaxation is permissible.
CWA section 303(d)(4) has two parts: paragraph (A), which applies to nonattainment waters, and
paragraph (B), which applies to attainment waters.
Nonattainment water: CWA section 303(d)(4)(A) allows the establishment of a less stringent
effluent limitation when the receiving water has been identified as not meeting applicable water
quality standards (i.e., a nonattainment water) if the permittee meets two conditions. First, the
existing effluent limitation must have been based on a total maximum daily load (TMDL) or
other wasteload allocation (WLA) established under CWA section 303. Second, relaxation of the
effluent limitation is only allowed if attainment of water quality standards will be ensured or the
designated use not being attained is removed in accordance with the water quality standards
regulations. This subsection does not provide an exception for establishing less stringent
limitations where the original limitation was based on state permitting standards (e.g., state
treatment standards) and was not based on a TMDL or WLA.
Attainment water: CWA section 303(d)(4)(B) applies to waters where the water quality equals
or exceeds levels necessary to protect the designated use, or to otherwise meet applicable water
quality standards (i.e., an attainment water). Under CWA section 303(d)(4)(B), a limitation based
on a TMDL, WLA, other water quality standard, or any other permitting standard may only be
relaxed where the action is consistent with state's antidegradation policy.
Although the statute also identifies six exceptions in section 402(o)(2) where effluent limitations
otherwise subject to the prohibition in section 402(o)(l) may be relaxed, the exceptions for technical
mistakes or mistaken interpretations and permit modification, which are described above, would not apply
to WQBELs.
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7.2.1.4 Exception Safety Clause
CWA section 402(o)(3) is a safety clause that provides an absolute limitation on backsliding. This section
of the CWA prohibits the relaxation of effluent limitations in all cases if the revised effluent limitation
would result in a violation of applicable effluent guidelines or water quality standards, including
antidegradation requirements. Thus, even if one or more of the backsliding exceptions outlined in the
statute is applicable and met, CWA section 402(o)(3) acts as a floor and restricts the extent to which
effluent limitations may be relaxed. The requirement affirms existing provisions of the CWA that require
effluent limitations, standards, and conditions to ensure compliance with applicable technology and water
quality standards.
7.2.2 Anti-backsliding Regulatory Provisions
Anti-backsliding regulations are found at Title 40 of the Code of Federal Regulations (CFR) 122.44(1).
The regulations do not specifically address backsliding where a permittee seeks relaxation of an effluent
limitation that is based on a state treatment standard or water quality standard [i.e., based on CWA section
301(b)(l)(C), 303(d) or 303(e)]. They do, however, address all other forms of backsliding.
First, the regulations at § 122.44(1)(1) restrict the relaxation of final effluent limitations and the relaxation
of standards or conditions contained in existing permits. Thus, this regulation, in effect, addresses all
types of backsliding not addressed in the CWA provisions (e.g., backsliding from limitations derived
from effluent guidelines, from new source performance standards, from existing case-by-case limitations
to new case-by-case limitations, and from conditions such as monitoring requirements that are not
effluent limitations). Under the regulation, a permittee must meet one of the causes for modification under
§ 122.62 for the reissued permit to allow relaxation of such limitations, standards, or conditions.
Second, the regulations at § 122.44(l)(2)(i) directly reflect the specific prohibition imposed by CWA
section 402(o) on backsliding where a permittee seeks to revise an existing case-by-case TBEL developed
using BPJ to reflect a subsequently promulgated effluent guideline that is less stringent than the case-by-
case requirement. The regulations include the same exceptions to this prohibition that are in CWA section
402(o)(2) and the same safety clause in CWA section 402(o)(3).
Thus, if the permit condition being considered for relaxation is either a case-by-case effluent limitation
developed using BPJ or is any other limitation, standard, or condition other than an effluent limitation
based on a state standard, the permit writer can apply the requirements in § 122.44(1). For effluent
limitations based on state standards, the permit writer should apply the provisions of CWA sections
402(o) and 303(d)(4) directly. Exhibit 7-2 illustrates the process of applying the statutory and regulatory
provisions addressing anti-backsliding.
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Exhibit 7-2 Application of anti-baeksliding requirements
Is effluent limitation based on a state standard? I
Yes
No
or
402(o)(1)/303(d)(4)
Are water quality standards attained?
402(o)(2)
Is a listed exception met?
Yes
303(d)(4)(B)
Attainment waters
Is revision consistent with
antidegradation?
Yes
i
No
Revision
not allowed
No
303(d)(4)(A)
Non-Attainment Waters
Is existing limit based on a
TMDLorWLA?
No
Yes
Is attainment of water
quality standards assured?
(including antidegradation)
No
Yes
402(o)(3)
Does revision comply with effluent
guidelines and water quality standards?
(including antidegradation)
Yes
Yes
No
Revision allowed
Revision not allowed
No
See existing
regulations
40 CFR 122.44 I
Exhibit 7-3 presents some examples of situations when backsliding might be a factor in effluent limitation
development.
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Exhibit 7-3 Backsliding examples
Example 1
A publicly owned treatment works (POTW) seeks to relax its WQBEL for Pollutant X
The current effluent limitation for Pollutant X is based on a TMDL and WLA for the POTW developed in
accordance with § 130.7.
The POTW is in compliance with its existing effluent limitation, and the applicable water quality standards for
Pollutant X are attained.
The POTW has developed new models with new river flow information. The models indicate that the water
quality standards for Pollutant X would be maintained with a relaxed permit limitation.
Question:
May the effluent limitation for Pollutant X be relaxed?
Answer:
Possibly. Under the interpretation discussed above, WQBELs may be relaxed where one of the exceptions in
CWA sections 402(o)(1 ) or (2) are met. In this case, although the new information from the models might meet the
exception requirements criteria under CWA section 402(o)(2)(B)(i), CWA section 402(o)(2) will not justify the
request unless the state reduces the pollutant loadings from other point sources or nonpoint sources of pollution.
That is because, as discussed in Section 7.1 above, CWA section 402(o)(2) restricts the use of new information to
cases where there is a decrease in the amount of pollutants being discharged.
The CWA section 402(o)(1) exceptions, on the other hand, might justify the request. In this case, the reference to
CWA section 303(d)(4)(B) in CWA section 402(o)(1) is the relevant exception. CWA section 303(d)(4)(B) provides
that, for receiving waters that meet water quality standards, permit limitations based on a TMDL or other WLA or
other permit standard may be relaxed if the state's antidegradation policy requirements are met.
Example 2
The state has established a technology-based treatment standard for fecal coliform pursuant to CWA section
The state later relaxes the standard in a revised regulation.
A POTW, which has been in violation of its effluent limitation for fecal coliform based on the old standard,
requests a revision of the limitation to reflect the new standard.
Water quality standards for fecal coliform are not being attained.
There was no TMDL or WLA developed. The basis of the effluent limitation was a state technology-based
treatment standard.
Question:
May the fecal coliform effluent limitation be relaxed?
Answer:
No. Under CWA section 402(o)(1), the applicable provision is CWA section 303(d)(4)(A). This subsection does not
authorize backsliding in this case (i.e., nonattainment waters) because it applies only to permit limitations based on
a TMDL or other WLA. Here, the limitation in question is based on a state technology-based treatment standard.
Furthermore, if the permit sought to apply the exceptions in CWA section 402(o)(2), the new information provision
would not allow the revision. For purposes of this section of the CWA, new information does not include revised
regulations.
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Exhibit 7-3 Backsliding examples (continued)
Example 3
The state has a narrative water quality criterion of no toxics in toxic amounts.
On the basis of WET testing data or other information, the state found that the discharge would cause, have
the reasonable potential to cause, or contribute to an excursion of the water quality standards in the receiving
waterspecifically the narrative water quality criterion.
The permitting authority imposed a WET limitation under § 122.44(d)(1)(v).
The permittee determines that Pollutant Z is the cause of WET measured in its discharge.
The permittee can demonstrate through sufficient data (including WET testing data) that an effluent limitation
for Pollutant Z will assure compliance with the narrative water quality criterion as well as the state's numeric
criteria for Pollutant Z, as required by § 122.44(d)(1)(v).
Question:
May the state modify the permit to delete the WET limitation and to add the effluent limitation for Pollutant Z?
Answer:
Possibly. CWA section 303(d)(4) might justify the action. The applicable provision is CWA section 303(d)(4)(B)
because the narrative water quality criterion is currently attained. The permittee is complying with the existing WET
limitation to attain and maintain the criterion. Under CWA section 303(d)(4)(B), the existing effluent limitation may
be relaxed as long as antidegradation requirements are met and the relaxed limitation will not cause a violation of
any effluent guidelines or water quality standards applicable to the discharge. In this case, it appears likely that a
relaxation would be permissible because the permittee can demonstrate that the new limitation for Pollutant Z will
assure compliance with both the narrative and numeric water quality criteria; however, the permit writer might
consider continuing WET monitoring to identify other potential sources of toxicity in the future.
Example 4
An industrial permittee seeks to revise its WQBEL of 60 mg/L for total suspended solids (TSS) to 100 mg/L,
which is its actual discharge level.
The current effluent limitation is based on a WLA from a TMDL developed in accordance with § 130.7.
The water quality standards are not being attained. The ambient concentration of TSS exceeds the applicable
water quality criteria.
An effluent limitation of 100 mg/L is consistent with applicable effluent guidelines.
New modeling information shows that the water quality standards will be attained with an effluent limitation of
75 mg/L TSS.
Question:
May the effluent limitation for TSS be revised from 60 mg/L to 100 mg/L?
Answer:
No; however, the effluent limitation could be relaxed to 75 mg/L under either CWA sections 402(o)(1) or (2)
exceptions.
The water quality standards are not being attained because of TSS. Therefore, under CWA section 402(o)(1), the
applicable exception is CWA section 303(d)(4)(A). In this case, the permitting authority may allow backsliding to
75 mg/L because the existing effluent limitation is based on a WLA from a TMDL, and the data show that
attainment of the water quality standards is assured with an effluent limitation of 75 mg/L (but not with a limitation
of 100 mg/L).
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CHAPTER 8. Monitoring and Reporting Conditions
This chapter describes the monitoring and reporting conditions that a permit writer establishes in a
National Pollutant Discharge Elimination System (NPDES) permit. The monitoring and reporting
conditions require the permittee to conduct routine or episodic self-monitoring of permitted discharges
and internal operations (where applicable) and report the analytical results to the permitting authority with
the information necessary to evaluate discharge characteristics and compliance status. Periodic
monitoring and reporting establish an ongoing record of the permittee's compliance status and, where
violations are detected, create a basis for any necessary enforcement actions.
The monitoring and reporting conditions section of an NPDES permit generally includes specific
requirements for the following items:
Monitoring locations.
Monitoring frequencies.
Sample collection methods.
Analytical methods.
Reporting and recordkeeping requirements.
The following sections provide an overview of the considerations involved in determining appropriate
monitoring, reporting, and recordkeeping requirements, and how to properly incorporate the appropriate
requirements in an NPDES permit.
8.1 Establishing Monitoring Conditions
The NPDES regulations require facilities discharging pollutants to waters of the United States to
periodically evaluate compliance with the effluent limitations established in their permits and provide the
results to the permitting authority. A permit writer should consider several factors when determining the
specific requirements to be included in the NPDES permit. Inappropriate or incomplete monitoring
requirements can lead to inaccurate compliance determinations. Factors that could affect sampling
location, sampling method, and sampling frequency include the following:
Applicability of effluent limitations guidelines and standards (effluent guidelines).
Wastestream and process variability.
Access to sample locations.
Pollutants discharged.
Effluent limitations.
Discharge frequencies (e.g., continuous versus intermittent).
Effect of flow or pollutant load or both on the receiving water.
Characteristics of the pollutants discharged.
Permittee's compliance history.
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8.1.1 Purposes of Monitoring
Monitoring is performed to determine compliance with effluent limitations established in NPDES
permits, establish a basis for enforcement actions, assess treatment efficiency, characterize effluents and
characterize receiving water.
Regulations requiring the establishment of monitoring and reporting conditions in NPDES permits are at
Title 40 of the Code of Federal Regulations (CFR) 122.44(i) and 122.48. Regulations at § 122.44(i)
require permittees to monitor pollutant mass (or other applicable unit of measure) and effluent volume
and to provide other measurements (as appropriate) using the test methods established at Part 136. That
subpart also establishes that NPDES permits (with certain specific exceptions as discussed in section
8.1.3 below) must require permittees to monitor for all limited pollutants and report data at least once per
year.
Regulations at § 122.48 stipulate that all permits must specify requirements concerning the proper use,
maintenance, and installation of monitoring equipment or methods (including biological monitoring
methods when appropriate). NPDES permits must also specify the monitoring type, intervals, and
frequency sufficient to yield data that are representative of the activity. The following sections focus on
developing permit monitoring conditions that properly address these regulatory requirements.
8.1.2 Monitoring Location
The permit writer should specify the appropriate monitoring location in an NPDES permit to ensure
compliance with the permit limitations and provide the necessary data to determine the effects of an
effluent on the receiving water. The NPDES regulations do not prescribe exact monitoring locations;
rather, the permit writer is responsible for determining the most appropriate monitoring location(s) and
indicating the location(s) in the permit. Ultimately, the permittee is responsible for providing a safe and
accessible sampling point that is representative of the discharge [§ 122.41(j)(l)].
The permit writer should consider the following questions when selecting a monitoring location:
Is the monitoring location on the facility's property?
Is the monitoring location accessible to the permittee and the permitting authority?
Will the results be representative of the targeted wastestream?
Is monitoring at internal points needed?
Permit writers should establish monitoring locations where the wastewater is well mixed, such as near a
Parshall flume or at a location in a sewer with hydraulic turbulence. Weirs tend to enhance the settling of
solids immediately upstream and the accumulation of floating oil or grease immediately downstream.
Such locations should be avoided for sampling.
The permit writer can specify monitoring locations with either a narrative description or a diagram of the
permittee's facility. Exhibit 8-1 provides examples of how to specify monitoring locations in a permit
either by narrative or by diagram.
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Exhibit 8-1 Examples of specifying monitoring locations in permits
Narrative
A. Monitoring Locations
1. Discharge from the Chemistry-Fine Arts Building must be sampled at the Parshall flume before the
discharge point for Outfall 001.
2. Discharge from the Physics Building must be sampled at the Parshall flume before the discharge point for
Outfall 002.
3. Discharge from the Research Lab No. 1 must be sampled at the Parshall flume before the discharge point
for Outfall 003.
A. Monitoring Locations
Outfall Description
Diagram
001
Discharge Pipe: Discharge of wastewater generated by all regulated metal finishing processes
at the facility. Samples must be collected at the point indicated on the diagram below.
Parshall Flume
Outfall
001
Receiving
Stream
* Sample Point
The monitoring location will vary depending on the type of monitoring required. The following sections
discuss monitoring location considerations for each monitoring type.
8,1,2,1
Influent monitoring is monitoring of a wastestream before that wastestream receives treatment. The
permit writer should require influent monitoring when a characterization of the influent is needed to
determine compliance with a permit condition, such as the 5-day biochemical oxygen demand (BOD5)
and total suspended solids (TSS) percent removal limitations required by the secondary treatment
standards for publicly owned treatment works (POTWs).
Source water monitoring is the monitoring of source water before use as process water (e.g., river water
used as contact cooling water). The permit writer should require source water monitoring if intake credits
are established as specified in § 122.45(g).
Influent and source water monitoring locations should ensure a representative sample of raw intake water
before any processes or treatment that could alter the properties of the intake water.
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8.1.2.2 Internal monitoring locations
Internal monitoring is the monitoring of wastestreams at a location within the facility before discharge to
waters of the United States. The NPDES regulations at § 122.45(h) allow internal monitoring points to be
established when needed to determine compliance with a standard and in cases where setting an external
monitoring location is not feasible. The permit writer may require internal monitoring to determine
compliance with technology-based effluent limitations (TBELs) for a wastestream before commingling
with other process or non-process wastestreams. Internal monitoring is generally not appropriate for
determining compliance with water quality-based effluent limitations (WQBELs) unless final effluent
monitoring is impractical (e.g., the final discharge point is submerged or inaccessible).
Examples of reasons for requiring designation of internal monitoring locations include the following:
Ensuring compliance with effluent guidelines (at non-POTW facilities): When non-process
wastewaters dilute process wastewaters subject to effluent guidelines, monitoring the combined
discharge might not accurately allow determination of whether the facility is complying with the
effluent guidelines. Under such circumstances, the permit writer might consider requiring
monitoring for compliance with TBELs before the process wastewater is combined with non-
process wastewater.
Ensuring compliance with secondary treatment standards (for POTWs only): Some POTWs
include treatment processes that do not address pollutants regulated by secondary treatment
standards and that could interfere with the ability to accurately monitor for compliance with
secondary treatment standards. Under such circumstances, the permit writer could consider
requiring monitoring for compliance with limitations derived from secondary treatment standards
before such processes. For example, the permit could require effluent monitoring for compliance
with limitations derived from secondary treatment standards after secondary clarification but
before disinfection.
Allowing detection of a pollutant: Instances could arise where the combination of process and
non-process wastewaters result in dilution of a pollutant of concern such that it would not be
detectable using approved analytical methods. Internal monitoring would enable characterization
of the pollutant before dilution with other wastewaters.
Where the permit writer determines that internal monitoring is necessary, § 122.45(h)(2) states that
limitations on internal wastestreams may be imposed only where the permit fact sheet sets forth the
exceptional circumstances requiring application of limitations at those locations.
8.1.2.3 Effluent monitoring locations
Effluent monitoring is monitoring of the final effluent after all treatment processes. The permit writer
should require effluent monitoring to determine compliance with final effluent limitations established in
the permit. Effluent monitoring also can be used to provide data to assess the possible impact of the
discharge on the receiving water.
Effluent monitoring locations should provide a representative sample of the effluent being discharged into
the receiving water. Effluent monitoring locations should be established after all industrial uses and
treatment processes. Most importantly, the point where a final effluent limitation applies and the point
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where monitoring is required must be the same. A logical effluent monitoring point is just before
discharge to the receiving water. This is particularly true for ensuring compliance with WQBELs.
8,1.3
The permit writer should establish monitoring frequencies sufficient to characterize the effluent quality
and to detect events of noncompliance, considering the need for data and, as appropriate, the potential
cost to the permittee. Monitoring frequency should be determined on a case-by-case basis, and decisions
for setting monitoring frequency should be described in the fact sheet. Some states have their own
monitoring guidelines that can help a permit writer determine an appropriate monitoring frequency.
To establish a monitoring frequency, the permit writer should consider the variability of the concentration
of various parameters by reviewing effluent data for the facility (e.g., from discharge monitoring reports
[DMRs]) or, without actual data, information from similar dischargers. A highly variable discharge
should require more frequent monitoring than a discharge that is relatively consistent over time
(particularly in terms of flow and pollutant concentration). Other factors that should be considered when
establishing appropriate monitoring frequencies include the following:
Design capacity of the treatment facility. The monitoring frequency might need to be increased
at facilities where the treatment facility is nearing design capacity. For example, at equivalent
average flow rates, a large lagoon system that is not susceptible to bypasses would require less
frequent monitoring than an overloaded treatment facility that experiences fluctuating flow rates
from infiltration or large batch discharges from an industrial user system. The lagoon should have
a relatively low variability compared to the facility receiving batch discharges.
Treatment method used. The monitoring frequency will be similar for similar treatment
processes. The type of wastewater treatment used by the facility might affect the frequency of
effluent monitoring. An industrial facility employing biological treatment would have a similar
monitoring frequency as a secondary treatment plant with the same units used for wastewater
treatment. If the treatment method is appropriate and achieving high pollutant removals on a
consistent basis, monitoring could be less frequent than for a plant with little or insufficient
treatment.
Compliance history. The monitoring frequency might need to be adjusted to reflect the
compliance history of the facility. A facility with problems achieving compliance generally
should be required to perform more frequent monitoring to characterize the source or cause of the
problems or to detect noncompliance.
Cost of monitoring relative to permittee's capabilities. The monitoring frequency should not
be excessive and should be what is necessary to provide sufficient information about the
discharge.
Location of the discharge. The monitoring frequency could be increased if the discharge is to
sensitive waters or is near a public water supply.
Nature of the pollutants. To accurately characterize the discharge, the monitoring frequency
might be increased for wastewaters with highly toxic pollutants or where the nature of the
pollutants varies.
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Frequency of the discharge. The monitoring frequency for a wastewater discharged in batches
infrequently should differ from that for a continuous discharge of highly concentrated wastewater
or a wastewater containing a pollutant that is found infrequently and at very low concentrations.
The production schedule of the facility (e.g., seasonal, daily), the plant washdown schedule, and
other similar factors should be considered.
Number of monthly samples used in developing effluent limitations. When establishing
monitoring frequency, the permit writer should consider the number of monthly samples used in
developing average monthly WQBELs. If the discharger monitors less frequently than the
monthly monitoring frequency assumed when developing applicable effluent guidelines or in
calculating a WQBEL, it could be more difficult for the discharger to comply with its average
monthly effluent limitations. For example, if an average monthly limitation is established
assuming a monitoring frequency of four times per month (i.e., the limit is the expected average
of four samples taken during a month), a discharger taking only one sample per month would
statistically have a greater chance of exceeding its average monthly limit than if it sampled at
least four times per month.
Tiered limitations. The monitoring frequency requirements should correspond to the applicable
tiers in cases where the permit writer has included tiered limitations. If a facility has seasonal
discharge limitations, it might be appropriate to increase the monitoring frequency during the
higher production season, and reduce the frequency during the off-season.
Other Considerations. To ensure representative monitoring, permit conditions could be included
to require monitoring on the same day, week, or month for parameters that might be correlated in
some way. For example, coordinating the monitoring requirements for parameters such as
pathogens and chlorine or metals and pH can provide information for both compliance
assessment and determination of treatment efficacy.
A permit writer could also establish a tiered monitoring schedule that reduces or increases the monitoring
frequency during a permit cycle. Tiered monitoring might be appropriate for discharges where the initial
sampling shows compliance with effluent limitations, justifying a reduction in monitoring frequency over
time. Conversely, if problems are found during the initial sampling, more frequent sampling and more
comprehensive monitoring can be applied. This step-wise approach could lead to lower monitoring costs
for permittees while still providing the data needed to demonstrate compliance with effluent limitations.
In 1996 EPA issued Interim Guidance for Performance-Based Reductions of NPDES Permit Monitoring
Frequencies . Under the guidance, NPDES reporting and monitoring
requirements may be reduced on the basis of a demonstration of excellent historical performance.
Facilities can demonstrate that historical performance by meeting a set of compliance and enforcement
criteria and by demonstrating their ability to consistently discharge pollutants below the levels necessary
to meet their existing NPDES permit limitations. Reductions are determined parameter-by-parameter, on
the basis of the existing monitoring frequency and the percentage below the limitation at which the
parameter is being discharged. The reductions are incorporated when the permit is reissued. To remain
eligible for the reductions, permittees are expected to maintain the parameter performance levels and
good compliance on which the reductions were based.
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8.1.4 Sample Collection
The permit writer must specify the sample collection method for all parameters required to be monitored
in the permit. The permit writer should determine the sample collection method on the basis of the
characteristics of each specific discharge. Certain sample collection and storage requirements are
identified as part of the analytical methods specified in Part 136. (Section 8.3 below presents more on
analytical methods.) The two most frequently used sampling methods are grab and composite. For more
detailed information on sample collection methods, permit writers should refer to Chapter 5 (Sampling) of
the NPDES Compliance Inspection Manual1
.
8.1.4.1 Grab Samples
Grab samples are individual samples collected over a period not exceeding 15 minutes and that are
representative of conditions at the time the sample is collected. Grab samples are appropriate when the
flow and characteristics of the wastestream being sampled are relatively constant. The sample volume
depends on the type and number of analyses to be performed. A grab sample is appropriate when a
sample is needed to
Monitor an effluent that does not discharge on a continuous basis.
Provide information about instantaneous concentrations of pollutants at a specific time.
Allow collection of a variable sample volume.
Corroborate composite samples.
Monitor parameters not amenable to compositing (e.g., temperature).
Grab samples can also be used to determine the spatial variability of a parameter or information on
variability over a short period. They also are useful for monitoring intermittent wastewater flows from
well-mixed batch process tanks.
8.1.4.2 Composite Samples
Composite samples are collected over time, either by continuous sampling or by mixing discrete samples,
and represent the average characteristics of the wastestream during the sample period. Composite samples
might provide a more representative measure of the discharge of pollutants over a given period than grab
samples, and are used when any of the following is true:
A measure of the average pollutant concentration during the compositing period is needed.
A measure of mass loadings per unit of time is needed.
Wastewater characteristics are highly variable.
Composite samples can be discrete samples (see discussion of sequential sampling in section 8.1.4.3
below) or a single combined sample and are collected either manually or with automatic samplers. There
are two general types of composite sampling: time-proportional and flow-proportional. The permit writer
should clearly express which type is required in the permit.
Time-proportional composite sample: This method collects a fixed volume (V) of discrete sample aliquots
in one container at constant time intervals (t) as shown in Exhibit 8-2.
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Exhibit 8-2 Visual interpretation of time-proportional composite monitoring
Time-proportional composite monitoring is appropriate when the flow of the sampled stream is constant
(flow rate does not vary more than ±10 percent of the average flow rate) or when flow-monitoring
equipment is not available. Automatically timed composited samples are usually preferred over manually
collected composites. Composite samples collected by hand are appropriate for infrequent analyses and
screening or if the subsamples have a fixed volume at equal time intervals.
Flow-proportional composite sample: There are two methods used for this type of sample: constant-
volume when the interval time varies between samples, or constant-time when the interval volume
collected varies between samples as shown in Exhibit 8-3.
V
Exhibit 8-3 Visual interpretation of flow-proportional composite monitoring
V
The constant-volume, flow-proportional, composite monitoring method collects a constant sample
volume at varying time intervals proportional to stream flow (e.g., 200 milliliters sample collected for
every 5,000 gallons of flow). The constant-time, flow-proportional, composite monitoring method
collects the sample by adjusting the volume of each aliquot as the flow varies, while maintaining a
constant time interval between the aliquots.
Flow-proportional composite sampling is usually preferred over time-proportional composite sampling
when the effluent flow volume varies appreciably over time. If there is no flow-measuring device,
effluent samples can be manually composited using the influent flow measurement without any correction
for time lag. The error in the influent and effluent flow measurement is insignificant except in those cases
where large volumes of water are impounded, as in equalization basins.
If a sampling protocol is not specified in the regulations, the permit writer should establish the duration of
the compositing period and frequency of aliquot collection. The permit writer should also establish the
time frame within which the sample is to be collected and the number of individual aliquots in the
composite.
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There are instances where composite samples are inappropriate. For example, the permit application
regulations at § 122.21(g)(7) indicate that grab samples must be used for sampling several parameters that
may change during the time it takes to composite the sample. Composite samples can be used for whole
effluent toxicity (WET) testing; however, if there is concern that there are toxicity spikes or that the
toxicant is a parameter for which composite sampling is not appropriate, grab samples for WET testing
could be specified in the permit.
8.1.4.3 Sequential and Continuous Monitoring
Sequential monitoring refers to collecting discrete samples in individual containers in regular succession,
such as timed intervals or discharge increments. Sequential grab samples provide a characteristic of the
wastestream over a given time. Automatic sequential monitoring may be done with a special type of
automatic sampling device that collects relatively small amounts of a sampled wastestream with the
interval between sampling proportioned based on either time or effluent flow. Unlike a combined
composite sampler, the sequential sampling device automatically retrieves a sample and holds it in a
bottle separate from other automatically retrieved samples. Many individual samples can be stored
separately in the unit rather than combining aliquots in a common bottle.
Continuous monitoring is another option for a limited number of parameters such as flow, total organic
carbon (TOC), temperature, pH, conductivity, residual chlorine, fluoride, and dissolved oxygen. When
establishing continuous monitoring requirements, the permit writer should be aware that the NPDES
regulations concerning pH limitations allow for a period of excursion when the effluent is being
continuously monitored (§401.17). The reliability, accuracy, and cost of continuous monitoring vary with
the parameter monitored. The permit writer should consider the environmental significance of the
variation of any of these parameters in the effluent and the cost of continuous monitoring before
establishing continuous monitoring requirements in the permit.
8.2 Additional Monitoring Requirements and WET Testing
A variety of discharges other than traditional POTW or industrial wastewater discharges, including
biosolids (sewage sludge), combined sewer and sanitary sewer overflows, and stormwater, are regulated
under the NPDES permit program. In addition, many permits include requirements for WET testing. As
discussed in this section, a permit writer should account for such unique discharges and testing
requirements in establishing monitoring requirements.
8.2.1 Biosolids (Sewage Sludge)
The purpose of monitoring sewage sludge is to ensure safe use or disposal of the sludge. Sewage sludge
regulations specified in Part 503 require monitoring of sewage sludge that is applied to land, placed on a
surface disposal site, or incinerated. The frequency of monitoring is based on the annual amount of
sewage sludge that is used or disposed of by those methods. POTWs that provide the sewage sludge to
another party for further treatment (such as composting) must provide that party with the information
necessary to comply with regulations at Part 503. Sewage sludge disposed of in a municipal solid waste
landfill unit must meet the criteria for municipal solid waste landfills in the regulations at Part 258.
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Exhibit 8-4 shows the minimum monitoring requirements established in Part 503 for sewage sludge
before use and disposal. More frequent monitoring for any of the required or recommended parameters is
appropriate when the POTW has any of the following:
A highly variable influent load of toxics or organic solids.
A significant industrial load.
A history of process upsets due to toxics, or of adverse environmental impacts due to sludge use
or disposal activities.
Exhibit 8-4 Minimum requirements for sewage sludge monitoring, based on method of sludge
use or disposal
Method
Monitoring requirements
Frequency
Citation
(40 CFR)
Land application
Sludge weight and percent total
solids
Metals: As, Cd, Cu, Pb, Hg, Mo,
Ni, Se, and Zn
Pathogen Density
Vector Attraction Reduction
Based on dry weight of sludge in metric
tons per year:
> zero but < 290: annually
= or > 290 but < 1,500: quarterly
= or > 1,500 but < 15,000: bimonthly
= or> 15,000: monthly
§503.16
Co-disposal in
municipal solid
waste landfill
Sludge weight and percent total
solids
Passes Paint-Filter Liquid Test
Suitability of sludge used as cover
Characterize in accordance with
hazardous waste rules
Monitoring requirements or frequency not
specified by Part 503. Determined by
local health authority or landfill
owner/operator.
Part 258
Surface
disposal:
lined sites with
leachate
collection and
unlined sites
Sludge weight and percent total
solids
Metals: As, Cr, Ni (Unlined sites
only)
Pathogen Density
Vector Attraction Reduction
Based on dry weight of sludge in metric
tons per year:
> zero but < 290: annually
= or > 290 but < 1,500: quarterly
= or > 1,500 but < 15,000: bimonthly
= or> 15,000: monthly
§ 503.26
Methane gas
Continuously
Sludge weight and percent total
solids
Metals: As, Cd, Cr, Pb, and Ni
Incineration
Based on dry weight of sludge in metric
tons per year:
> zero but < 290: annually
= or > 290 but < 1,500: quarterly
= or > 1,500 but < 15,000: bimonthly
= or> 15,000: monthly
Be and Hg (National Emissions
Standards)
As required by permitting authority
(local air authority)
§ 503.46
THC or 62, moisture, combustion
temperatures
Continuously
Air pollution control device
operating parameters
As required by permitting authority
Notes:
Monitoring frequencies required by Part 503 may be reduced after 2 years of monitoring, but in no case may be less than once
per year.
A successful land application program could necessitate sampling for other constituents of concern (such as nitrogen) in
determining appropriate agronomic rates. The permit writer will determine additional monitoring requirements.
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The sampling and analysis methods specified in § 503.8 and Part 136 should be followed for monitoring
the required parameters. Without any specific methods in Part 503, guidance on appropriate methods is in
the following documents:
Part 503 Implementation Guidance2 .
POTW Sludge Sampling and Analysis Guidance Document .
Control of Pathogens and Vector Attraction in Sewage Sludge4
< www.epa. gov/ORD/NRMRL/pubs/625r92013/625r92013 .htm>.
4
8.2.2 Combined Sewer Overflows (CSOs) and Sanitary Sewer Overflows
(SSOs)
EPA's Combined Sewer Overflow (CSO) Control Policy (59 FR 18688, April 19, 1994) requires
monitoring to characterize the combined sewer system, assist in developing a Long-Term Control Plan
(LTCP), and show compliance with permit requirements. The permit writer should ensure the following:
Monitoring is done to develop an initial system characterization as part of the nine minimum
controls to reduce CSOs and their effect on receiving water quality. Such monitoring includes
analyzing existing data on precipitation events, on the combined sewer system and CSOs, on
water quality, and conducting field inspections.
As part of the LTCP, a permittee is required to develop a more complete characterization of the
sewer system through monitoring and modeling.
To show compliance with the permit requirements and ultimately the attainment of water quality
standards, the permittee is required to conduct a post-construction compliance monitoring
program. Specific monitoring requirements of the post-construction compliance monitoring
program will be unique to each permittee's LTCP and should be established as specific
monitoring conditions in the individual NPDES permit.
These monitoring conditions should require monitoring of certain key parameters during a representative
number of CSOs from a representative number of wet-weather events along with ambient water quality
monitoring to ascertain attainment of water quality standards. EPA has prepared a guidance manual on
monitoring entitled Combined Sewer Overflows: Guidance for Monitoring and Modeling5
.
A facility's permit might also contain monitoring requirements for sanitary sewer overflows (SSOs). SSO
monitoring requirements would be developed on a case-by-case basis.
8.2.3 Stormwater Monitoring Considerations
Storm water monitoring requirements vary according to the type of permit regulating the Stormwater
discharge and the activity. Municipal separate storm sewer systems (MS4s) serving more than 100,000
people (and some serving less than 100,000) are typically issued individual NPDES permits with
monitoring requirements that are specific to the MS4. Smaller MS4s regulated under the Stormwater Phase
II rule are typically not required to conduct water quality monitoring as a condition in their NPDES general
permit, though evaluation of measurable goals may include monitoring. EPA's multi-sector general permit
(MSGP) for Stormwater discharges from industrial facilities includes analytical monitoring requirements
based on the type of industrial activity. Finally, operators of construction activity regulated under the
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construction general permit are typically not required to conduct water quality monitoring; however, some
states and EPA Regions do require monitoring if the construction activity will discharge to a water
impaired by sediment.
Specific monitoring conditions for the federal general stormwater permits are detailed in the most recent
Construction General Permit or MSGP issued by EPA (available on the EPA Stormwater Program
Website ). Additional documents on stormwater monitoring are:
Urban Stormwater BMP Performance: A Guidance Manual for Meeting the National Stormwater
BMP Database Requirements6 .
Guidance Manual for the Monitoring and Reporting Requirements of the NPDES Stormwater
Multi-Sector General Permit (MSGP)1 .
8.2.4 WET Monitoring
The use of WET testing to evaluate the toxicity in a receiving stream is discussed in section 6.4 of this
manual and on the NPDES WET Website . The WET (or biomonitoring) test
procedures were promulgated in § 136.3 (60 FR 53529, October 16, 1995). EPA revised the WET
methods in 67 FR 69951, November 19, 2002. WET monitoring conditions included in permits should
specify the particular biomonitoring test to be used, the test species, required test endpoints, and quality
assurance/quality control procedures.
To support permitting agencies in implementing WET methods, EPA has revised and published manuals
for toxicity test protocols:
Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and
Marine Organisms. 5th ed.8 .
Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to
Freshwater Organisms. 4th ed.9 .
Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to
Marine and Estuarine Organisms. 3rd ed.10 .
NPDES Compliance Monitoring Inspector Training: Biomonitoring11 (No Link).
WET testing samples could be composite or grab samples. Twenty-four hour composite samples are
suggested except when any of the following are true:
The effluent is expected to be more toxic at a certain time of day.
Toxicity may be diluted during compositing.
The size of the sample needed exceeds the composite sampler volume.
WET tests are relatively expensive compared to single parameter tests. Therefore, a permit writer should
carefully consider the appropriate frequency for WET testing. A discharge with highly variable flow or
observed toxicity should have more frequent monitoring than a discharge that is relatively consistent over
time. As with other parameters, factors that a permit writer should consider when establishing appropriate
WET monitoring frequencies include the following:
Type of treatment process.
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Environmental significance and nature of the toxicity.
Past compliance record or history.
Cost of monitoring relative to financial capabilities.
Number of monthly samples used in developing the permit limitation.
The frequency of intermittent discharges.
Samples should be evenly spaced throughout the year so that seasonal variability can be ascertained.
8.3 Analytical Methods
The permit writer must specify the analytical methods to be used for monitoring. EPA's Office of Science
and Technology's Clean Water Act Analytical Methods Website
contains information about analytical methods.
The standard conditions of the permit [§§ 122.41(j)(4) and 122.44(i)] require that, when available,
permittees use test procedures specified in Part 136 . The
analytical methods contained in Part 136 are established for conventional, toxic (priority), and some
nonconventional pollutants. Without analytical methods for a parameter, the permit writer should specify
the analytical method to be used. There are also procedures to apply for approval of alternative test
methods in accordance with § 136.4.
While Part 136 identifies the analytical methods approved for use in the NPDES program, additional
methods information is available through the National Environmental Methods Index (NEMI)
. NEMI is a Web-based, searchable clearinghouse of methods supported by the U.S.
Geological Survey and EPA's Office of Water. NEMI contains summaries of more than 1,100 methods
and describes them by their performance characteristics and their regulatory status, relative cost, detection
level, detection level type, accuracy, precision, spiking level, instrumentation, lab equipment, and the
greenness of analytic methods. Permit writers might find that information useful in comparing the
features of Part 136 methods that will be used for assessing compliance with the calculated effluent
limitations.
When establishing effluent limitations for a specific parameter (based on technology or water quality
regulatory requirements), it is possible for the value of the calculated limit to fall below the method
detection limit (MDL) and the minimum level (ML) established by the approved analytical method(s).
Regardless of whether current analytical methods are available to detect and quantify the parameter at the
concentration of the calculated limitation, the limitation must be included in the permit as calculated.
In some instances, there might be two or more approved Part 136 analytical methods available for the
analysis of a parameter. In such cases, the permit should determine whether there is a need to select one
of the approved methods and to include a requirement in the permit mandating the use of only the selected
method. That approach might be necessary where an effluent limit is established at a level that is
quantifiable by one approved method but is below the ML of another approved method.
Such a situation often occurs where a permit contains a WQBEL for mercury. To clarify the EPA's
position with respect to effluent monitoring for mercury, EPA developed a memo Analytical Methods for
Mercury in National Pollutant Discharge Elimination System (NPDES) Permits12
.
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Sufficiently Sensitive Methods
At the time of the writing of this manual, EPA had proposed regulations at §§ 122.21 (e), 122.44(i), and
Part 136, to require the use of sufficiently sensitive methods for analyses conducted for NPDES permit
applications and for compliance monitoring (75 FR 35712, June 23, 2010). To ensure that appropriate
analytical methods are required and performed, see the most current version of these federal
regulations and applicable state analytical method regulations and policy.
8.4 Reporting Monitoring Results
The NPDES regulations require the permittee to maintain records and periodically report on monitoring
activities. The regulations at § 122.41(l)(4)(i) require that monitoring results must be reported on a DMR
. Data reported include both data required by the permit and any additional
data the permittee has collected consistent with permit requirements. All facilities must submit reports (on
discharges and sludge use or disposal) at least annually, as required by § 122.44(i)(2). POTWs with
pretreatment programs must submit a pretreatment report at least annually as required by § 403.12(i).
However, the NPDES regulation states that monitoring frequency and reporting should be dependent on
the nature and effect of the discharge or sludge use or disposal. Thus, the permit writer can require
reporting more frequent than annually.
8.5 Recordkeeping Requirements
Generally, the permit writer is required by § 122.41(j) to include in the permit the requirement to retain
records for at least three years, subject to extension by the State Director. Recordkeeping requirements for
sewage sludge [§ 122.41(j)] and the CAFO program [§ 122.42(e)(2)] require records be kept five years or
longer if required by the State Director. The permit writer should designate in the permit where records
should be kept.
Monitoring records must include the following:
Date, place, time of sampling.
Name of sampler.
Date of analysis.
Name of analyst.
Analytical methods used.
Analytical results.
According to § 122.41(j), monitoring records must be representative of the discharge. Monitoring records,
which must be retained, include continuous strip chart recordings, calibration data, copies of all reports
for the permit, and copies of all data used to compile reports and applications.
Sewage sludge regulations under §§ 503.17, 503.27, and 503.47 establish recordkeeping requirements
that vary depending on the use and disposal method for the sewage sludge. The same recordkeeping
requirements should be applied to other sludge monitoring parameters not regulated by the Part 503 rule.
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1 U.S. Environmental Protection Agency. 2004. NPDES Compliance Inspection Manual. EPA-305-X-03-001. U.S.
Environmental Protection Agency, Office of Enforcement and Compliance Assurance, Washington, DC.
.
2 U.S. Environmental Protection Agency. 1995. Part 503 Implementation Guidance. EPA 833-R-95-001. U.S. Environmental
Protection Agency, Office of Water, Washington, DC. .
3 U.S. Environmental Protection Agency. 1989. POTWSludge Sampling and Analysis Guidance Document. EPA-833-B-89-100.
U.S. Environmental Protection Agency, Office of Water, Washington, DC. .
4 U.S. Environmental Protection Agency. 1992. Control of Pathogens and Vector Attraction in Sewage Sludge. EPA-625/R-92-
013. U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC.
.
U.S. Environmental Protection Agency. 1999. Combined Sewer Overflows-Guidance forMonitoring andModeling. EPA-832-
B-99-002. U.S. Environmental Protection Agency, Office of Water, Washington, DC. .
6 U.S. Environmental Protection Agency. 2002. Urban Stornnvater BMP Performance: A Guidance Manual for Meeting the
National Stormwater BMP Database Requirements. EPA-821-B-02-001. U.S. Environmental Protection Agency, Office of
Water, Washington, DC. .
7 U.S. Environmental Protection Agency. 1999. Guidance Manual for the Monitoring and Reporting Requirements of the NPDES
Stormwater Multi-Sector General Permit (MSGP). U.S. Environmental Protection Agency, Office of Water, NPDES Program
Branch, Washington, DC. .
8 U.S. Environmental Protection Agency. 2002. Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to
Freshwater and Marine Organisms, Fifth Edition. EPA-821-R-02-012. U.S. Environmental Protection Agency, Office of Water,
Washington, DC .
9 U.S. Environmental Protection Agency. 2002. Short-Term Methods for Estimating the Chronic Toxicity of Effluents and
Receiving Waters to Freshwater Organisms, Fourth Edition. EPA-821-R-02-013. U.S. Environmental Protection Agency, Office
of Water, Washington, DC. .
10 U.S. Environmental Protection Agency. 1994. Short-Term Methods for Estimating the Chronic Toxicity of Effluents and
Receiving Waters to Marine andEstuarine Organisms, Third Edition. EPA821-R-02-014. U.S. Environmental Protection
Agency, Office of Water, Washington, DC. .
11 U.S. Environmental Protection Agency. 1990. NPDES Compliance Monitoring Inspector Training: Biomonitoring.
U.S. Environmental Protection Agency, Office of Water Enforcement and Permits, Washington, DC. NTIS # PB91-145854.
(No Link)
12 Hanlon, James A. 2007. Analytical Methods for Mercury in National Pollutant Discharge Elimination System (NPDES)
Permits. U.S. Environmental Protection Agency, Office of Wastewater Management. Memorandum, August 23,2007.
.
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CHAPTER 9. Special Conditions
Special conditions in National Pollutant Discharge Elimination System (NPDES) permits supplement
numeric effluent limitations and require the permittee to undertake activities designed to reduce the
overall quantity of pollutants being discharged to waters of the United States, to reduce the potential for
discharges of pollutants, or to collect information that could be used in determining future permit
requirements.
There are many different reasons to incorporate special conditions into a permit including:
To address unique situations, such as facilities discharging pollutants for which data are absent or
limited, making development of technology- or water quality-based effluent limitations (TBELs
or WQBELs) more difficult or impossible.
To incorporate preventive requirements, such as requirements to install process control alarms,
containment structures, good housekeeping practices, and the like.
To address foreseeable changes to discharges, such as planned changes to process, products, or
raw materials that could affect discharge characteristics.
To incorporate compliance schedules to provide the time necessary to comply with permit conditions.
To incorporate other NPDES programmatic requirements (e.g., pretreatment, sewage sludge).
To impose additional monitoring requirements that provide the permit writer with data to evaluate
the need for changes in permit limitations.
To increase or decrease monitoring requirements, depending on monitoring results or changes in
processes or products.
To impose requirements for special studies such as ambient stream surveys, toxicity identification
evaluations (TIEs) and toxicity reduction evaluations (TREs), bioaccumulation studies, sediment
studies, mixing or mixing zone studies, pollutant reduction evaluations, or other such
information-gathering studies.
Section 9.1 below addresses several types of special conditions that apply to both municipal and non-
municipal facilities. Section 9.2 addresses special conditions unique to municipal facilities.
9.1 Special Conditions Potentially Applicable to Any Type of
Discharger
This section discusses several types of special conditions that could be included in any NPDES permit
(i.e., municipal or non-municipal). Those special conditions can be thought of as the ABCs of special
conditions and include the following:
Additional monitoring and special studies.
Best management practices (BMPs).
Compliance schedules.
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A summary of the use of those special conditions follows.
9.1.1 A dditional Monitoring and Special Studies
Additional monitoring requirements, beyond those required under the effluent limitations section of the
permit, and special studies are useful for collecting data that were not available to the permit writer for
consideration during permit development. Additional monitoring requirements and special studies
generally are used to supplement numeric effluent limitations or support future permit development
activities. Examples of the types of special studies that could be required in an NPDES permit include the
following:
Treatability studies: Might be required in a permit when insufficient treatability information for
a pollutant or pollutants would hinder a permit writer from developing defensible TBELs.
Treatability studies can also be required when the permit writer suspects that a facility might not
be able to comply with an effluent limitation.
Toxicity identification evaluation/toxicity reduction evaluation (TIE/TRE): Could be
required in a permit when wastewater discharges are found to be toxic using whole effluent
toxicity (WET) tests. The purpose of those evaluations is to identify and control the sources of
toxicity in an effluent. Further guidance related to U.S. Environmental Protection Agency (EPA)
recommended TIE/TRE procedures and requirements is found in the following guidance
manuals:
Toxicity Reduction Evaluation Guidance for Municipal Wastewater Treatment Plants1
< www.epa.gov/npdes/pubs/tre.pdf>.
Clarifications Regarding Toxicity Reduction and Identification Evaluations in the National
Pollutant Discharge Elimination System Program2 .
Generalized Methodology for Conducting Industrial Toxicity Reduction Evaluations3
(No linksee the endnote for ordering instructions).
- Methods for Aquatic Toxicity Identification Evaluations: Phase I Toxicity Characterization
Procedures. 2nd ed4 .
Toxicity Identification Evaluation: Characterization of Chronically Toxic Effluents, Phase I5
.
- Methods for Aquatic Toxicity Identification Evaluations: Phase II Toxicity Identification
Procedures for Samples Exhibiting Acute and Chronic Toxicity6
.
- Methods for Aquatic Toxicity Identification Evaluations: Phase III Confirmation Procedures
for Samples Exhibiting Acute and Chronic Toxicity1 .
Mixing or mixing zone studies: Might be required in a permit to assist in determining how
effluent and receiving water mix and in establishing a regulatory mixing zone that can be applied
when developing WQBELs.
Sediment monitoring: Could be included in a permit if a permit writer suspects that pollutants
contained in wastewater discharges accumulate in the sediments of the receiving water.
Bioaccumulation studies: Might be required in a permit to determine whether pollutants
contained in wastewater discharges bioaccumulate in aquatic organisms (e.g., fish, invertebrates).
Such studies could be required when water quality criteria are expressed in terms offish tissue
levels. Additional guidance related to evaluating the bioaccumulation potential of a pollutant can
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be found in the EPA Great Lakes Water Quality Initiative Technical Support Document for the
Procedure to Determine Bioaccumulation Factors* (No linksee the endnote for ordering instructions).
When establishing additional monitoring or special studies, permit writers must ensure that any
requirements related to the study (e.g., special sampling or analytical procedures) are specified in the
appropriate permit condition. In addition, permit writers should establish a reasonable schedule for
completion and submission of the study or monitoring program. If the anticipated timeline is longer than
one year, an interim progress report during the study is advisable.
9.1.2 Best Management Practices (BMPs)
In general, BMPs are actions or procedures to prevent or reduce the discharge of pollution to waters of the
United States. Title 40 of the Code of Federal Regulations (CFR) section 122.2 includes the following in
the definition of BMPs:
Schedules of activities.
Prohibitions of practices.
Maintenance procedures.
Treatment requirements.
Operating procedures and practices to control
Plant site runoff.
Spillage or leaks.
Sludge or waste disposal.
- Drainage from raw material storage areas.
9.1.2.1 When to Use BMPs
Clean Water Act (CWA) section 304(e) authorizes EPA to require BMPs as part of effluent limitations
guidelines and standards (effluent guidelines) to control plant site runoff, spillage or leaks, sludge or
waste disposal, and drainage from raw material storage that it determines are associated with or ancillary
to the industrial manufacturing or treatment process and can contribute significant amounts of pollutants
to navigable waters. Where effluent guidelines require specific control measures, including BMPs or
development of a BMP plan, permit writers must include such requirements in permits. In addition, CWA
section 402(p)(3)(B)(iii) states that permits for discharges from municipal storm sewers must require
controls, including management practices, to reduce the discharge of pollutants. Finally, CWA sections
402(a)(l) and (2) give the permitting authority the ability to include BMPs in permits on a case-by-case
basis to carry out the provisions of the CWA.
The NPDES regulations at § 122.44(k) track the statutory provisions cited above. This section of the
regulations provides that permits must contain BMPs (when applicable) to control or abate the discharge
of pollutants when any of the following are true:
They are authorized under CWA section 304(e).
They are authorized under CWA section 402(p) for the control of stormwater discharges.
Numeric effluent limitations are infeasible.
The practices are necessary to achieve effluent limitations and standards or carry out the purpose
and intent of the CWA.
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Circumstances under which numeric effluent limitations might be infeasible include the following:
Regulating a pollutant for which limited treatability or aquatic impact data are available to allow
development of numeric TBELs or WQBELs.
Regulating discharges when the types of pollutants vary greatly over time.
In addition, a permit writer should consider using BMPs under any of the following circumstances:
When chemical analyses are inappropriate or impossible.
When there is a history of leaks and spills or when housekeeping is sloppy.
When a complex facility lacks data for a pollutant or pollutants.
9.1.2.2 in NPDES Permits
Permit writers include BMP requirements in permits using two approaches: (1) site-, process-, or
pollutant-specific BMPs, or (2) a requirement to develop a BMP plan. Site-, process-, or pollutant-specific
BMPs might be appropriate in the case of an individual permit where a permit writer has the opportunity
to review the circumstances at the facility. On the other hand, it might not be appropriate to include site-,
process-, or pollutant-specific BMPs as conditions in a general permit, a permit for a particularly complex
facility, or a permit for a facility with operations not familiar to the permit writer. Instead, complicated
facilities and discharges covered under a general permit could be required to develop a BMP plan that
requires the permittee to determine appropriate BMPs on the basis of circumstances at its facility.
Specific BMPs
Specific BMPs are designed to address conditions particular to a type of facility or to a specific site,
process, or pollutant. Specific BMPs might be used in a permit when
They are needed to address ancillary activities that could result in the discharge of pollutants to
waters of the United States.
Numeric effluent limitations for a specific process are otherwise infeasible and BMPs serve as
effluent limitations for that process.
They are required to supplement and ensure compliance with effluent limitations in the permit.
To select a specific BMP, the permit writer could
Review the industry profiles or the specific facility to determine the applicable and appropriate
management practices.
Evaluate whether the BMP would help to achieve effluent limitations or other environmental
objectives for that facility.
Use information from other permits, pollution prevention sources, and EPA guidance documents
to identify applicable and appropriate BMPs.
Specific BMPs frequently are required for certain types of dischargers such as concentrated animal
feeding operations (CAFOs), combined sewer overflows (CSOs), and stormwater discharges.
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BMP Plans
The Guidance Manual for Developing Best Management Practices9
describes the activities and materials at an industrial or municipal facility that are best addressed by
BMPs. The manual also describes how BMPs work and gives examples of types of BMPs.
If a permit writer requires a BMP plan, it is the facility's responsibility to develop, implement, and
evaluate the success or shortfalls of its own plan. Often, a BMP committee (i.e., a group of individuals
within the plant organization) is responsible for developing the BMP plan and assisting the plant
management in implementing and updating the BMP plan.
EPA has identified several recommended components of effective BMP plans and detailed each
component in the Guidance Manual for Developing Best Management Practices . The minimum
suggested components of a general BMP plan are presented below:
General Provisions
Name and location of facility.
Statement of BMP policy and obj ective .
- Review by plant manager.
Specific Provisions
BMP committee.
- Risk identification and assessment.
Reporting of BMP incidents.
- Materials compatibility.
Good housekeeping.
Preventive maintenance.
Inspections and records.
Security.
- Employee training.
BMP plans used to supplement effluent limitations or to describe how the discharger plans to meet
effluent limitations can be submitted to the regulatory agency or be kept on-site and made available to the
permitting authority upon request. A general schedule for BMP plan development can be included in the
permit (e.g., complete and submit the plan within six months of permit issuance and begin implementing
the plan within nine months of permit issuance).
Exhibit 9-1 presents example permit text for a requirement to develop and implement a BMP plan and
should be adapted as necessary to reflect conditions at the individual facility.
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Exhibit 9-1 Example BMP plan requirement
The following is example text for requiring development and implementation of a BMP plan through an NPDES
permit. The text should be crafted and changed as necessary to meet the individual facility's needs and the
permitting authority's goals. The bracketed text should be updated to be specific to the permit.
1. Implementation.
[IF A BMP PLAN DOES NOT EXIST:]
The permittee, must develop and implement a best management practices (BMP) plan that achieves the
objectives and the specific requirements listed below. A copy of the plan must be submitted to the U.S.
Environmental Protection Agency (EPA) [AND/OR STATE AGENCY] within six months of the effective date
of this permit. The plan must be implemented as soon as possible but no later than nine months from the
effective date of the permit. The permittee must update and amend the plan as needed.
[IF A BMP PLAN ALREADY EXISTS:]
The permittee must during the term of this permit operate the facility in accordance with the BMP plan [CITE
EXISTING PLAN] and in accordance with subsequent amendments to the plan. The permittee must amend
the plan to incorporate practices to achieve the objectives and specific requirements listed below, and a copy
of the amended plan must be submitted to the U.S. Environmental Protection Agency (EPA) [AND/OR STATE
AGENCY] within three months of the effective date of this permit. The amended plan must be implemented as
soon as possible but not later than six months from the effective date of the permit.
2. Purpose
Through implementation of the BMP plan the permittee must prevent or minimize the generation and the
potential for the release of pollutants from the facility to the waters of the United States through normal
operations and ancillary activities.
3. Objectives
The permittee must develop and amend the BMP plan consistent with the following objectives for the control
of pollutants.
a. The number and quantity of pollutants and the toxicity of effluent generated, discharged, or potentially
discharged at the facility must be minimized by the permittee to the extent feasible by managing each
influent waste stream in the most appropriate manner.
b. Under the BMP plan, and any Standard Operating Procedures (SOPs) included in the plan, the permittee
must ensure proper operation and maintenance of the treatment facility as required by § 122.41(e).
c. The permittee must establish specific objectives for the control of pollutants by conducting the following
evaluations.
1. Each facility component or system must be examined for its waste minimization opportunities and its
potential for causing a release of significant amounts of pollutants to waters of the United States
because of equipment failure, improper operation, and natural phenomena such as rain or snowfall,
etc. The examination must include all normal operations and ancillary activities including material
storage areas, plant site runoff, in-plant transfer, process and material handling areas, loading or
unloading operations, spillage or leaks, sludge and waste disposal, or drainage from raw material
storage. [NOTE THAT ONLY THE APPLICABLE AREAS SHOULD BE INCLUDED IN THE PREVIOUS LIST.]
2. Where experience indicates a reasonable potential for equipment failure (e.g., a tank overflow or
leakage), natural condition (e.g., precipitation), or other circumstances that may result in significant
amounts of pollutants reaching surface waters, the program should include a prediction of the
direction, rate of flow and total quantity of pollutants that could be discharged from the facility as a
result of each condition or circumstance.
4. Requirements
The BMP Plan must be consistent with the objectives in the Objectives section above and the general
guidance contained in the publication entitled Guidance Manual for Developing Best Management Practices
(BMPs), EPA 833-B-93-004, or any subsequent revisions to the
guidance document. The BMP plan must
a. Be documented in narrative form, must include any necessary plot plans, drawings or maps, and must be
developed in accordance with good engineering practices. The BMP plan must be organized and written
with the following structure:
1. Name and location of the facility.
2. Statement of BMP policy.
3. Structure, functions, and procedures of the BMP Committee.
4. Specific management practices and standard operating procedures to achieve the above objectives,
including the following:
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Exhibit 9-1 Example BMP plan requirement (continued)
a. Modification of equipment, facilities, technology, processes, and procedures.
b. Reformulation or redesign of products.
c. Substitution of materials.
d. Improvement in management, inventory control, materials handling or general operational
phases of the facility.
5. Risk identification and assessment.
6. Reporting of BMP incidents.
7. Materials compatibility.
8. Good housekeeping.
9. Preventative maintenance.
10. Inspections and records.
11. Security.
12. Employee training.
b. Include the following provisions concerning BMP plan review:
1. Review by plant engineering staff and the plant manager.
2. Review and endorsement by the permittee's BMP Committee.
3. A statement that the above reviews have been completed and that the BMP plan fulfills the
requirements set forth in this permit. The statement must include the dated signatures of each BMP
Committee member as certification of the reviews.
c. Establish specific BMPs to meet the objectives identified in the Objectives section above, addressing
each component or system capable of generating or causing a release of significant amounts of
pollutants, and identifying specific preventive or remedial measures to be implemented.
d. Establish specific BMPs or other measures that ensure that the following specific requirements are met:
1. Ensure proper management of solid and hazardous waste in accordance with regulations
promulgated under the Resource Conservation and Recovery Act (RCRA). Management practices
required under RCRA regulations must be referenced in the BMP plan.
2. Reflect requirements for Spill Prevention, Control, and Countermeasure (SPCC) plans under Clean
Water Act (CWA) section 311 and 40 CFR Part 112 and may incorporate any part of such plans into
the BMP plan by reference.
3. Reflect requirements for stormwater control under CWA section 402(p) and the regulations at 40
CFR 122.26 and 122.44, and otherwise eliminate to the extent practicable, contamination of
stormwater runoff.
etc.
[NOTE: SECTION d. ABOVE COULD BE TAILORED TO EACH FACILITY BY THE PERMIT WRITER AND MAY
INCLUDE PROCESSES OR AREAS OF THE FACILITY WITH HOUSEKEEPING PROBLEMS, NONCOMPLIANCE,
SPILLS/LEAKS, OR OTHER PROBLEMS THAT COULD BE REMEDIED THROUGH A BMP. IF THERE IS A KNOWN
SOLUTION TO THE PROBLEM (E.G., MORE FREQUENT INSPECTIONS, PREVENTIVE MAINTENANCE, ETC.), THIS
REMEDY COULD ALSO BE INCLUDED AS A PART OF THE BMP PLAN REQUIREMENTS. TO GATHER IDEAS FOR
SUCH REQUIREMENTS, THE PERMIT WRITER MAY WANT TO CONTACT THE PERMITTEE, COMPLIANCE
PERSONNEL, FACILITY INSPECTORS, OPERATIONS OFFICE PERSONNEL, AND STATE AGENCY
COUNTERPARTS. THE PERMIT WRITER MIGHT ALSO WANT TO CHECK REQUIREMENTS IN OTHER PERMITS
AND BMP PLANS FOR SIMILAR FACILITIES.]
5. Documentation
The permittee must maintain a copy of the BMP plan at the facility and must make the plan available to EPA
[AND/OR STATE AGENCY] upon request. All offices of the permittee, which are required to maintain a copy
of the NPDES permit, must also maintain a copy of the BMP plan.
6. BMP Plan Modification
The permittee must amend the BMP plan whenever there is a change in the facility, or in the operation of the
facility, that materially increases the generation of pollutants or their release or potential release to the
receiving waters. The permittee must also amend the plan, as appropriate, when plant operations covered by
the BMP plan change. Any such changes to the BMP plan must be consistent with the objectives and specific
requirements listed above. All changes in the BMP plan must be reported to EPA [AND/OR STATE
AGENCY] in writing.
7. Modification for Ineffectiveness
If at any time the BMP plan proves to be ineffective in achieving the general objective of preventing and
minimizing the generation of pollutants and their release and potential release to the receiving waters and/or
the specific requirements above, the permit and/or the BMP plan must be subject to modification to
incorporate revised BMP requirements.
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9.1.2.3 Pollution Prevention in BMPs
BMPs are, by their nature, pollution prevention practices. Traditionally, BMPs have focused on good
housekeeping measures and good management techniques that attempt to avoid contact between
pollutants and water as a result of leaks, spills, and improper waste disposal. However, on the basis of the
authority granted under the regulations, BMPs may include a range of pollution prevention options,
including production modifications, operational changes, materials substitution, and materials and water
conservation.
When developing BMPs, permit writers should be familiar with the fundamental principles of pollution
prevention:
Pollution should be prevented or reduced at the source, whenever feasible (Reduce).
Pollution that cannot be prevented should be reused or recycled in an environmentally safe
manner, whenever feasible (Reuse-Recycle).
Pollution that cannot be prevented or recycled should be treated in an environmentally safe
manner, whenever feasible (Treat).
Disposal or other release into the environment should be employed only as a last resort and
should be conducted in an environmentally safe manner (Dispose of).
When writing an NPDES permit, a permit writer who has familiarity with a certain type of processes
might identify pollution prevention practices that are not used at a facility and that would help that facility
achieve its pollution prevention goals. Where the pollution prevention practices are necessary to carry out
the purposes and intent of the CWA, the permit writer may develop BMPs to implement those practices.
9.1.3 Compliance Schedules
The NPDES regulations at § 122.47 allow permit writers to establish schedules of compliance to give
permittees additional time to achieve compliance with the CWA and applicable regulations. Schedules
developed under this provision must require compliance by the permittee as soon as possible, but may not
extend the date for final compliance beyond compliance dates established by the CWA. Thus, compliance
schedules in permits are not appropriate for every type of permit requirement. Specifically, a permit
writer may not establish a compliance schedule in a permit for TBELs because the statutory deadlines for
meeting technology standards (i.e., secondary treatment standards and effluent guidelines) have passed.
This restriction applies to both existing and new dischargers. Permit writers should note, however, that
§ 122.29(d)(4) allows a new source or new discharger up to 90 days to start-up its pollution control
equipment and achieve compliance with its permit conditions (i.e., provides for up to a 90-day period to
achieve compliance).
Examples of requirements for which a compliance schedule in an NPDES permit might be appropriate
include:
Pretreatment program development.
Sludge use and disposal program development and implementation.
BMP plan development and implementation.
Effluent limitations derived from new or revised water quality standards.
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An EPA Administrator's decision specifically addresses compliance schedules for effluent limitations
derived from new or revised water quality standards. In the decision In the Matter ofStar-Kist Caribe,
Inc., documented in the memorandum Order Denying Modification Request With Respect to the
Administrator's 1990 Decision in Star-Kist Caribe, Inc. (NPDES Appeal No. 88-5)10
. the EPA Administrator interpreted CWA section 301(b)(l)(C) to
mean that 1) after July 1, 1977, permits may not contain compliance schedules for effluent limitations
based on water quality standards adopted before July 1, 1977, and 2) compliance schedules are allowed
for effluent limitations based on standards adopted after that date only if the state has clearly indicated in
its water quality standards or implementing regulations that it intends to allow them.
In May 2007, the Director of EPA's Office of Wastewater Management issued a memorandum to EPA
Region 9 that clarified the requirements of § 122.47 as they relate to WQBELs [see Compliance
Schedules for Water Quality-Based Effluent Limitations in NPDES Permits11
. Permit writers should consider the principles
outlined in this memo when assessing whether a compliance schedule for achieving a WQBEL is
consistent with the CWA and its implementing regulations and when documenting the basis for a
compliance schedule in a permit. Considerations outlined in the memo include the following:
Demonstrate that the permittee cannot immediately comply with the new effluent limitation on
the effective date of the permit.
Include an enforceabley/«a/ effluent limitation and a date for achievement in the permit.
Justify and document the appropriateness of the compliance schedule; factors relevant to a
determination that a compliance schedule is appropriate include how much time the discharger
had to meet the WQBEL under prior permit(s), whether there is any need for modifications to
treatment facilities, operations, or other measures and, if so, how long it would take to implement
such modifications.
Justify and demonstrate that compliance with the final WQBEL is required as soon as possible;
factors relevant to a determination that a compliance is required as soon as possible include the
steps needed to modify or install treatment facilities, operations, or other measures and the time
those steps would take.
Include an enforceable sequence of events leading to compliance with interim milestones for
schedules longer than one year.
Recognize that a schedule solely to provide time to develop a total maximum daily load (TMDL)
or to conduct a use attainability analysis (UAA) is not appropriate.
Many of the principles outlined in the memo could be more generally applied to compliance schedules for
requirements other than WQBELs.
9.2 Special Conditions for Municipal Facilities
This section explains several common special conditions that are applicable only to municipal facilities.
These conditions reflect requirements for publicly owned treatment works (POTWs) to implement and
enforce local pretreatment programs for their industrial users; biosolids (sewage sludge) disposal
requirements; CSO requirements; SSO requirements; and municipal separate storm sewer system (MS4)
requirements.
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9.2.1 The National Pretreatment Program
CWA section 402(b)(8) requires that certain POTWs receiving pollutants from significant industrial
sources (subject to CWA section 307(b) standards) establish a pretreatment program to ensure compliance
with these standards. The implementing regulations at § 403.8(a) state that:
Any POTW (or combination of POTWs operated by the same authority) with a total design flow
greater than 5 million gallons per day (mgd) and receiving from industrial users pollutants which pass
through or interfere with the operation of the POTW or are otherwise subject to pretreatment
standards will be required to establish a POTW pretreatment program unless the NPDES state
exercises its option to assume local responsibilities as provided in § 403.10(e).
As specified in § 403.8(a), the Regional Administrator or Director of an authorized state may require a
POTW with a design flow of 5 mgd or less to develop a POTW pretreatment program. Program
development could be determined to be necessary to prevent interference with or pass through of the
POTW based on the nature, or volume, of the industrial influent, a history of treatment process upsets and
violations of POTW effluent limitation(s), and contamination of municipal sludge.
Since 1978, approximately 1,500 POTWs have been required to develop and implement pretreatment
programs through special conditions of NPDES permits. The pretreatment program was developed to
control industrial discharges to POTWs and to meet the following objectives:
To prevent pass through of pollutants.
To prevent interference with POTW processes, including interference with the use or disposal of
municipal sludge.
To improve opportunities to recycle and reclaim municipal and industrial wastewater and sludges.
The pretreatment program also helps ensure POTW personnel health and safety.
As authorized by the pretreatment regulations at §§ 403.8(c), 403.8(d) and 403.8(e) and the NPDES
regulations at § 122.44(j)(2), the requirements to develop and implement a POTW pretreatment program
are included as enforceable conditions in the POTWs NPDES permit. NPDES permits drive the
development and implementation of pretreatment programs by requiring the following:
Adequate legal authority.
Maintenance of an industrial user inventory.
Development and implementation of local limits.
Control mechanisms issued to significant industrial users (SIUs).
Compliance monitoring activities.
Swift and effective enforcement.
Data management and recordkeeping.
Reporting to the approval authority (EPA or state).
Public participation.
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Through the NPDES permit, the POTW is required to develop and implement a pretreatment program.
The POTW is required to submit an approvable program that meets the requirements in § 403.9(b). A
more detailed description of these required program elements is in § 403.8(f). The POTW must have the
legal authority enabling it to do the following:
Deny or condition new or increased contributions of pollutants, or changes in nature of pollutants,
to the POTW by industrial users.
Require compliance with applicable pretreatment standards and requirements by industrial users.
Control through a permit, order, or similar means the contribution to the POTW by each
industrial user to ensure compliance with applicable pretreatment standards and requirements.
These control mechanisms must have certain conditions as laid out in § 403.8(f)(l)(iii) and be
enforceable.
Require the development of compliance schedules where necessary by each industrial user for the
installation of technology required to meet applicable pretreatment standards and requirements,
and submission of all notices and self-monitoring reports to assess and ensure compliance.
Carry out all inspection, surveillance, and monitoring procedures necessary to determine
compliance with applicable pretreatment standards and requirements independent of information
submitted by the industrial user (including the authority to enter the premises of the industrial
user).
Obtain remedies for noncompliance (e.g., injunctive relief, penalties).
Comply with confidentiality requirements.
Further, at a minimum, the POTW must have procedures to do the following:
Identify and locate all possible industrial users that might be subject to the POTW pretreatment
program.
Identify the character and volume of pollutants contributed to the POTW by the industrial users.
Notify industrial users of applicable pretreatment standards and applicable requirements under
CWA sections 204(b) and 405 and RCRA Subtitles C and D.
Receive and analyze self-monitoring reports.
Conduct sampling, inspections and other surveillance activities to determine compliance with
applicable pretreatment standards and requirements independent of information supplied by the
industrial user.
Investigate instances of noncompliance.
Comply with public participation requirements, including annual public notice of industrial users
determined to be in significant noncompliance during the previous 12-month period.
Also, as part of the POTW pretreatment program, POTWs must have adequate resources and funding to
implement the program, evaluate the need for and, as necessary, develop local limits and develop an
enforcement response plan.
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The NPDES permit should include the conditions specified in § 403.9, including that the POTW be
required to submit the program documentation, detailing the authority and procedures to be implemented,
along with other information about the program. The permit will allow the POTW up to one year, from
the time when written notification from the approval authority determined the need for a pretreatment
program, to develop and submit a program for approval as stated in § 403.8(b). Once the permitting
authority reviews and approves the program, the requirement to implement the approved program is then
incorporated into the permit.
The permit writer generally incorporates the requirement to develop a pretreatment program at the time of
permit reissuance. The requirement, however, may also be incorporated through a modification of the
permit if there is cause, as defined in detail in § 403.8(e), to make such a modification. The permit writer
must follow procedures outlined by § 122.62 related to modifications when including the requirement to
develop a pretreatment program in an NPDES permit
During the life of the permit, it might be necessary for the POTW to modify its approved pretreatment
program (changes to local limits, changes to the ordinance, and such). The changes can be brought about
by the POTW's desire to change the way the program operates, or they can be the result of changes that
are necessary to address deficiencies in the program found during inspections or audits done by the
permitting authority. Whatever the reason for the modification, the permitting authority must review and
approve any modification to the approved program that is considered substantial, as required by § 403.18.
All substantial program modifications to the POTW's approved pretreatment program require minor
modifications to the NPDES permit and are subject to the procedural requirements in §§ 122.63(g) and
403.18. In addition, incorporating the requirement for a previously approved pretreatment program for the
purpose of making the implementation of the program an enforceable part of the permit is also considered
a minor modification to the NPDES permit.
The majority of POTWs that need pretreatment program requirements in their permits currently have
them in place. In addition, an NPDES state or an EPA region will often designate a pretreatment
coordinator to serve as the pretreatment expert to review the annual report from the POTW and
recommend any action to be taken. The state or EPA regional pretreatment coordinator is a key resource
on pretreatment issues, particularly at the time of NPDES permit reissuance. EPA regions and approved
states have developed standard pretreatment development or implementation conditions (with minor
modifications made to tailor the conditions to the specific discharger) that are placed in all applicable
NPDES permits in that region or state. The permit writer can usually obtain examples of these NPDES
pretreatment conditions from the EPA or state pretreatment coordinators. The permit writer might need to
update or modify pretreatment implementation language or initiate corrective action related to the
pretreatment program.
EPA has developed the Pretreatment Program Website and prepared a
number of guidance manuals for POTWs on how to implement their local pretreatment programs that are
accessible through this website. In addition, EPA prepared the Introduction to the National Pretreatment
Program12 as a reference for anyone interested in understanding the
basics of pretreatment program requirements and to provide a roadmap to additional and more detailed
guidance materials for those trying to implement specific elements of the pretreatment program.
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Pretreatment program information and monitoring data obtained through the POTW's pretreatment
program are useful to the permit writer in identifying possible modifications to the pretreatment
program's local limits or procedures, or the need for water quality-based controls. The permit writer
should obtain such data with the aid of the pretreatment coordinator. Permits must include conditions
requiring a POTW to provide a written technical evaluation of the need to revise local limits under
§ 403.5(c)(l) following permit issuance or reissuance [§ 122.44(j)(2)(ii)]. In addition, POTWs with a
design flow greater than or equal to one mgd and with an approved pretreatment program or required to
develop a pretreatment program must sample and analyze their effluent for priority (toxic) pollutants
listed in Part 122, Appendix J, Table 2 as part of the permit application process [see § 122.21(j)(4)(iv)].
Those data and information also are useful for determining the need for WQBELs.
9.2.2 Biosolids (Sewage Sludge)
CWA section 405(d) requires that EPA regulate the use and disposal of sewage sludge to protect public
health and the environment from any reasonably anticipated adverse effects of these practices. In the
CWA, Congress directed EPA to develop technical standards for municipal sludge use and disposal
options and enacted strict deadlines for compliance with these standards. Within one year of promulgation
of the standards, compliance was required unless construction of new pollution control facilities was
necessary, in which case compliance was required within two years.
EPA promulgated Part 503, Standards for the Use or Disposal of Sewage Sludge in 58 Federal Register
(FR) 9248, February 19, 1993, with amendments in 59 FR 9095, February 19, 1994 and 60 FR 54764,
October 25, 1995. These regulations address four sludge use and disposal practices: land application,
surface disposal, incineration, and disposal in a municipal solid waste landfill. The standards for each end
use and disposal method consist of general requirements, numeric effluent limitations, operational
standards, and management practices, as well as monitoring, recordkeeping, and reporting requirements.
Unlike technology standards, which are based on the ability of treatment technologies to reduce the level
of pollutants, EPA's sewage sludge standards are based on health and environmental risks. Part 503
imposes requirements on four groups:
Persons who prepare sewage sludge or material derived from sewage sludge.
Land appliers of sewage sludge.
Owners/operators of sewage sludge surface disposal sites.
Owners/operators of sewage sludge incinerators.
Details of that rule are described in A Plain English Guide to the EPA Part 503 Biosolids Rule13
.
The risk assessment for the Part 503 rule that governs the land application of biosolids took nearly 10
years to complete and had extensive rigorous review and comment. The risk assessment evaluated and
established limitations for a number of pollutants. These limitations are in chapter 4 of A Guide to the
Biosolids Risk Assessments for the EPA Part 503 Rule14 .
The regulation is largely self-implementing, and anyone who engages in activities covered by the
regulation must comply with the appropriate requirements on or before the compliance deadlines. A
person who violates Part 503 requirements is subject to administrative, civil, and criminal enforcement
actions.
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CWA section 405(f) requires the inclusion of sewage sludge use or disposal requirements in any NPDES
permit issued to a Treatment Works Treating Domestic Sewage (TWTDS) and authorizes the issuance of
sewage sludge-only permits to non-discharging TWTDS. In response, EPA promulgated revisions to the
NPDES permit regulations at Parts 122 and 124 in 54 FR 18716, May 2, 1989, to address inclusion of
sewage sludge use and disposal standards in NPDES permits and NPDES permit issuance to treatment
works that do not have an effluent discharge to waters of the United States, but are involved in sewage
sludge use or disposal as preparers, appliers, or owners/operators. TWTDS includes all sewage sludge
generators and facilities, such as blenders, that change the quality of sewage sludge.
EPA recognizes that implementation of Part 503 requirements is a source of confusion for permit writers
and permittees who might already have NPDES permits with special conditions addressing sewage sludge
requirements. EPA has provided several guidance documents to help clarify NPDES permitting
expectations, and explain the requirements of Part 503:
Part 503 Implementation Guidance15 .
Land Application of Sewage SludgeA Guide for Land Appliers on the Requirements of the
Federal Standards for the Use or Disposal of Sewage Sludge Management in 40 CFR Part 50316
.
Surface Disposal of Sewage SludgeA Guide for Owners/Operators of Surface Disposal
Facilities on the Monitoring, Recordkeeping, and Reporting Requirements of the Federal
Standards for the Use or Disposal of Sewage Sludge in 40 CFR Part 5031? .
Preparing Sewage Sludge for Land Application or Surface DisposalA Guide for Preparers of
Sewage Sludge on the Monitoring, Record Keeping, and Reporting Requirements of the Federal
Standards for the Use or Disposal of Sewage Sludge in 40 CFR Part 50318 .
Domestic Septage Regulatory Guidance, A Guide to the EPA 503 Rule19
< www.epa.gov/npdes/pubs/owm0026.pdf>.
Control of Pathogens and Vector Attraction in Sewage Sludge10
.
The permit writer should refer to the Part 503 Implementation Guidance and EPA Region and state
guidelines or policies for instructions on how to implement the applicable Part 503 standards into the
permit. The permit writer will need to determine the type of sewage sludge use or disposal practice(s)
used by the discharger and apply the appropriate Part 503 standards. In general, conditions will need to be
established to address the following:
Pollutant concentrations or loading rates.
Operational standards (such as pathogen and vector attraction reduction requirements for land
application and surface disposal and total hydrocarbons (THC) concentrations for incinerators).
Management practices (e.g., siting restrictions, design requirements, operating practices).
Monitoring requirements (e.g., pollutants to be monitored, sampling locations, frequency, and
sample collection and analytical methods).
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Recordkeeping requirements.
Reporting requirements (e.g., contents of reports and frequency or due dates for submission of
reports).
General requirements (e.g., specific notification requirements before land application, submission
of closure and post closure plan for surface disposal sites).
In addition to any specific applicable Part 503 standards, three boilerplate conditions must be written in
the NPDES permit where applicable. These consist of the following:
Text requiring the POTW/TWTDS to comply with all existing requirements for sewage sludge
use and disposal, including the Part 503 standards [see § 122.44(b)(2)].
A reopener clause, which authorizes reopening a permit to include technical standards if the
technical standards are more stringent or more comprehensive than the conditions in the permit
[see § 122.44(c)].
A notification provision requiring the permittee to give notice to the permitting authority when a
significant change in the sewage sludge use or disposal practice occurs (or is planned) [see
standard conditions in § 122.41(l)(l)(iii)].
If permit conditions based on existing regulations are insufficient to protect public health and the
environment from adverse effects that could occur from toxic pollutants in sewage sludge, permit
conditions should be developed on a case-by-case basis using best professional judgment (BPJ) to fulfill
the statutory requirement. The Part 503 Implementation Guidance contains information to assist permit
writers in developing effluent limitations and management practice requirements on a case-by-case basis
to protect public health and the environment from adverse effects that could occur from toxic pollutants in
sewage sludge. For more information on biosolids, see section 2.3.1.3 of this manual and the Biosolids
Website
9.2.3 Combined Sewer Overflows (CSOs)
Combined sewer systems were designed and built in the 19th and early 20th centuries to collect sanitary
and industrial wastewater and stormwater runoff. During dry weather, combined sewers carry sanitary
wastes and industrial wastewater to a treatment plant. In periods of heavy rainfall, however, stormwater is
combined with untreated wastewater, which can overflow and discharge directly to a waterbody without
being treated. These overflows are called combined sewer overflows (CSOs).
EPA published a CSO Control Policy in 59 FR 18688, April 19, 1994. That policy represents a
comprehensive national strategy to ensure that municipalities, permitting authorities, water quality
standards authorities, and the public engage in a comprehensive and coordinated planning effort to
achieve cost-effective CSO controls that ultimately meet appropriate health and environmental objectives.
The CSO Control Policy includes expectations for NPDES permitting authorities. In general, EPA
envisioned a phased permit approach, including initial requirements to implement Nine Minimum CSO
Controls (NMC) and develop a Long-Term CSO Control Plan (LTCP), followed by requirements to
implement the controls in the approved LTCP. The Wet Weather Water Quality Act of 2000 amended the
CWA to add section 402(q), which required that CSO permits be issued in conformance with the CSO
Control Policy.
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CSOs are point source discharges subject to both the technology-based requirements of the CWA and
applicable state water quality standards. Under the CWA, CSOs must comply with Best Available
Technology Economically Achievable (BAT) for nonconventional and toxic pollutants and Best
Conventional Technology (BCT) for conventional pollutants. However, there are no promulgated BAT or
BCT limitations in effluent guidelines for CSOs. As a result, permit writers must use BPJ in developing
technology-based permit requirements for controlling CSOs. Permit conditions also must achieve
compliance with applicable water quality standards.
The 1994 CSO Control Policy contains the recommended approach for developing and issuing NPDES
permits to control CSOs. In addition, EPA has developed the following CSO guidance documents to help
permit writers and permittees implement the CSO Control Policy:
Combined Sewer Overflows-Guidance for Long-Term Control Plan21
.
Combined Sewer Overflows-Guidance for Nine Minimum Controls22
.
Combined Sewer Overflows-Guidance for Screening and Ranking2^ .
Combined Sewer Overflows-Guidance for Monitoring and Modeling24
.
Combined Sewer Overflows-Guidance for Financial Capability Assessment and Schedule
Development .
Combined Sewer Overflows-Guidance for Funding Options26
.
Combined Sewer Overflows-Guidance for Permit Writers21 .
Combined Sewer Overflows-Guidance: Coordinating Combined Sewer Overflow Long-Term
Planning with Water Quality Standards Reviews2* .
Combined Sewer Overflows-Guidance for Permit Writers24 contains guidance and example permit
language that permit writers can use. Controlling CSOs typically requires substantial long-term planning,
construction, financing and continuous reassessment; therefore, the implementation of CSO controls will
probably occur over several permit cycles. The guidance explains a phased permitting approach to CSOs.
Exhibit 9-2 depicts this phased permitting approach and the types of permit conditions that should be
developed for each phase.
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NPDES permit
Exhibit 9-2 Categories of CSO permitting conditions
Phase I Phase II
Post phase II
A. Technology-based
B. Water Quality-based
C. Monitoring
D. Reporting
E. Special conditions
NMC, at a minimum
Narrative
Characterization,
monitoring, and
modeling of CSS
Documentation of NMC
implementation
Interim LTCP
deliverables
Prohibition of dry
weather overflows
(DWO)
Development of LTCP
NMC, at a minimum
Narrative + performance-
based standards
Monitoring to evaluate
water quality impacts
Monitoring to determine
effectiveness of CSO
controls
Implementation of CSO
controls (both NMC and
long-term controls)
Prohibition of DWO
Implementation of LTCP
Reopener clause for
water quality standards
violations
Sensitive area
reassessment
NMC, at a minimum
Narrative + performance-
based standards +
numeric WQBELs (as
appropriate)
Post-construction
compliance monitoring
Report results of post-
construction compliance
monitoring
Prohibition of DWO
Reopener clause for
water quality standards
violations
Depending on the permittee's situation, a permit may contain both Phase I and Phase II elements. Phase I
permits require demonstration of implementation of the NMC, shown in Exhibit 9-3.
Exhibit 9-3 Nine minimum CSO controls
1. Proper operation and regular maintenance programs for the sewer system and the CSOs
2. Maximum use of the collection system for storage
3. Review and modification of pretreatment requirements to ensure that CSO impacts are minimized
4. Maximization of flow to the POTW for treatment
5. Prohibition of CSOs during dry weather
6. Control of solid and floatable materials in CSOs
7. Establishment of pollution prevention programs
_ Public notification to ensure that the public receives adequate notification of CSO occurrences and
CSO impacts
9. Monitoring to effectively characterize CSO impacts and the efficacy of CSO controls
In the Phase I permit issued/modified to reflect the CSO Control Policy, the NPDES authority should at
least require permittees to
Immediately implement BAT/BCT, which at a minimum includes the NMC, as determined on a
BPJ basis by the permitting authority.
Develop and submit a report documenting the implementation of the NMC within 2 years of
permit issuance/modification.
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Comply with applicable water quality standards, no later than the date allowed under the state's
water quality standards expressed in the form of a narrative limitation.
Develop and submit, consistent with the CSO Control Policy and based on a schedule in an
appropriate enforceable mechanism, an LTCP, as soon as practicable, but generally within 2 years
after the effective date of the permit issuance/modification. Permitting authorities may establish a
longer timetable for completion of the long-term CSO control plan on a case-by-case basis to
account for site-specific factors that could influence the complexity of the planning process.
Exhibit 9-4 shows the minimum elements of the LTCP.
Exhibit 9-4 Elements of the long-term CSO control plan
1. Characterization, monitoring, and modeling of the combined sewer system
2. Public participation
3. Consideration of sensitive areas
4. Evaluation of alternatives
5. Cost/performance considerations
6. Operational plan
7. Maximizing treatment at the existing POTW treatment plant
8. Implementation schedule
9. Post-construction compliance monitoring program
Phase II permits require the implementation of an LTCP. The Phase II permit should contain the
following:
Requirements to implement the technology-based controls including the NMC determined on a
BPJ basis.
Narrative requirements that ensure that the selected CSO controls are implemented, operated and
maintained as described in the LTCP.
Water quality-based effluent limits under §§ 122.44(d)(l) and 122.44(k), requiring, at a
minimum, compliance with, no later than the date allowed under the state's water quality
standards, the numeric performance standards for the selected CSO controls, based on average
design conditions specifying at least one of the following:
A maximum number of overflow events per year for specified design conditions consistent
with II.C.4.a.i of the CSO Control Policy.
- A minimum percentage capture of combined sewage by volume for treatment under specified
design conditions consistent with II.CAa.ii of the CSO Control Policy.
- A minimum removal of the mass of pollutants discharged for specified design conditions
consistent with II.C.4.a.iii of CSO Control Policy.
Performance standards and requirements that are consistent with II.C.4.b of the CSO Control
Policy.
A requirement to implement, with an established schedule, the approved post-construction water
quality assessment program including requirements to monitor and collect sufficient information
to demonstrate compliance with water quality standards and protection of designated uses as well
as to determine the effectiveness of CSO controls.
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A requirement to reassess overflows to sensitive areas in those cases where elimination or
relocation of the overflow is not physically possible and economically achievable.
Conditions establishing requirements for maximizing the treatment of wet-weather flows at the
POTW, as appropriate, consistent with section II.C.7. of the CSO Policy.
A reopener clause authorizing the NPDES authority to reopen and modify the permit upon
determination that the CSO controls fail to meet water quality standards or protect designated
uses.
Reviewing the permittee's LTCP and consultations with other staff involved in the CSO control process
and the permittee are important steps in the process of determining the appropriate Phase II permit
conditions. Water quality-based controls in Phase II generally are expressed as narrative requirements and
performance standards for the combined sewer system. Finally, post Phase II permit conditions would
address continued implementation of the NMC, long-term CSO controls, and post-construction
compliance monitoring. There may also be numeric WQBELs when there are sufficient data to support
their development.
LTCP implementation schedules were expected to include project milestones and a financing plan for
design and construction of necessary controls as soon as practicable. The CSO Control Policy expected
permitting authorities to undertake the following:
Review and revise, as appropriate, state CSO permitting strategies developed in response to the
National CSO Control Strategy.
Develop and issue permits requiring CSO communities to immediately implement the NMC and
document their implementation and develop and implement an LTCP.
Promote coordination among the CSO community, the water quality standards authority, and the
general public through LTCP development and implementation.
Evaluate water pollution control needs on a watershed basis and coordinate CSO control with the
control of other point and nonpoint sources of pollution.
Recognize that it might be difficult for some small communities to meet all the formal elements
of LTCP development, and that compliance with the NMC and a reduced scope LTCP might be
sufficient.
Consider sensitive areas, use impairment, and a CSO community's financial capability in the
review and approval of implementation schedules.
Communities must develop and implement LTCPs to meet water quality standards, including the
designated uses and criteria to protect those uses for waterbodies that receive CSO discharges. The CSO
Control Policy recognized that substantial coordination and agreement among the permitting authority,
the water quality standards authority, the public, and the CSO community would be required to
accomplish this objective. The CSO Control Policy also recognized that the development of the LTCP
should be coordinated with the review and appropriate revision of water quality standards and their
implementation procedures.
In developing permit requirements to meet technology-based requirements and applicable state water
quality standards, the permit writer, in conjunction with staff involved in water quality standards and the
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permittee, should identify the appropriate site-specific considerations that will determine the CSO
conditions to be established in the permit. EPA believes that the following information will be
particularly relevant in developing the appropriate conditions:
CSO Discharge
Flow, frequency, and duration of the CSO discharge.
- Available effluent characterization data on the CSO discharge.
- Available information and data on the impacts of the CSO discharge(s) (e.g., CWA section
305(b) reports, ambient survey data, fish kills, CWA section 303(d) lists of impaired waters).
Compliance history of the CSO owner, including performance and reliability of any existing
CSO controls.
Current NPDES permit and NPDES permit application.
- Facility planning information from the permittee that addresses CSOs.
Technologies
Performance data (either from the manufacturer or from other applications) for various CSO
technologies that may be employed, including equipment efficiency and reliability.
- Cost information associated with the installation, operation and maintenance of CSO
technologies.
Reference materials on various types of CSO.
For more information on CSOs, see section 2.3.1.4 of this manual and the Combined Sewer Overflows
Website .
9.2.4 Sanitary Sewer Overflows (SSOs)
EPA's Report to Congress on the Impacts and Control of CSOs and SSOs29
shows that NPDES permit requirements establishing clear reporting,
recordkeeping and third party notification of overflows from municipal sewage collection systems, as
well as clear requirements to properly operate and maintain the collection system, are critical to effective
program implementation. NPDES authorities should be improving NPDES permit requirements for SSOs
and sanitary sewer collection systems, which could lead to improved performance of municipal sanitary
sewer collection systems and improved public notice for SSO events.
The NPDES regulations provide standard conditions that are to be in NPDES permits for POTWs as
discussed in Chapter 10 of this manual. Standard conditions in a permit for a POTW apply to portions of
the collection system for which the permittee has ownership or has operational control. When reissued,
permits for POTW discharges should clarify how key standard permit conditions apply to SSOs and
sanitary sewer collection systems. On August 20, 2007, EPA circulated a draft fact sheet, NPDES Permit
Requirements for Municipal Sanitary Sewer Collection Systems and SSOs
. which explains the ways NPDES permitting
authorities should be improving implementation of NPDES permit requirements to address SSOs and
sanitary sewer collection systems.
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The draft fact sheet indicates that clarifications should address the particular application of standard
permit conditions to SSOs and municipal sanitary sewer collection systems as discussed below.
Immediate reporting. Permits should clarify that the permittee is required to notify the NPDES
authority of an overflow that could endanger health or the environment from portions of the
collection system over which the permittee has ownership or operational control as soon as
practicable but within 24 hours of the time the permittee becomes aware of the overflow.
[See § 122.41(1)(6)].
Written reports. Permits should clarify that the permittee is required to provide the NPDES
authority a written report within 5 days of the time it became aware of any overflow that is
subject to the immediate reporting provision. [See § 122.41(l)(6)(i).] In addition, permits should
clarify that any overflow that is not immediately reported as indicated above, should be reported
in the discharge monitoring report. [See § 122.41(1)(7)].
Third party notice. Permits should establish a process for requiring the permittee or the NPDES
authority to notify specified third parties of overflows that could endanger health because of a
likelihood of human exposure; or unanticipated bypass and upset that exceeds any effluent
limitation in the permit or that could endanger health because of a likelihood of human exposure.
Permits should clarify that the permittee is required to develop, in consultation with appropriate
authorities at the local, county, or state level (or any combination), a plan that describes how,
under various overflow (and unanticipated bypass and upset) scenarios, the public, and other
entities, would be notified of overflows that may endanger health. The plan should identify all
overflows that would be reported, to whom they should be reported, the specific information that
would be reported, a description of lines of communication, and the identities of responsible
officials. [See § 122.41(0(6)].
Recordkeeping. Permits should clarify that the permittee is required to keep records of
overflows. Clarified permit language for recordkeeping should require the permittee to retain the
reports submitted to the NPDES authority and other appropriate reports that could include work
orders associated with investigation of system problems related to an overflow, that describes the
steps taken or planned to reduce, eliminate, and prevent reoccurrence of the overflow.
[See § 122.410)].
Capacity, management, operation and maintenance programs. Permits should clarify
requirements for proper operation and maintenance of the collection system. [See §§ 122.41(d)
and 122.41(e)]. This may include requiring the development and implementation of capacity,
management, operation and maintenance (CMOM) programs. EPA's Region 4 has developed
materials and guidance that can help a municipality with its CMOM program on the
Management. Operation and Maintenance (MOM) Programs Project Website
. The CMOM program may use a process for self-
assessment and information management techniques for ongoing program improvement and may
develop and implement emergency response procedures to overflows. In addition, the CMOM
permit condition may specify appropriate documentation requirements, including the following:
- CMOM program summary. Permittees may be required to develop a written summary of their
CMOM programs, which would be available to the NPDES authority and public on request.
The program summary would give an overview of the management program and summarize
major implementation activities.
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Program audit report. Permittees may be required to conduct comprehensive audits of their
programs during the permit cycle, and submit a copy of the audit report to the NPDES
authority with the application for permit renewal. EPA's Sanitary Sewer Overflow Toolbox
Website provides information on CMOM.
System evaluation and capacity assurance plan. Capacity assurance refers to a process to
identify, characterize and address hydraulic deficiencies in a sanitary sewer collection system.
The permit may require the permittee to implement a program to assess the current capacity
of the collection system and treatment facilities that they own or over which they have
operational control to ensure that discharges from unauthorized locations do not occur. Where
peak flow conditions contribute to an SSO discharge or to noncompliance at a treatment
plant, the permittee may be required to prepare and implement a system evaluation and
capacity assurance plan. In some instances, the permittee may already be under an
enforceable obligation and schedule, in which case this permit provision would be redundant
and, thus, unnecessary.
Section 2.3.1.5 of this manual and EPA's Sanitary Sewer Overflows Website
provide more information on SSOs.
1 U.S. Environmental Protection Agency. 1999. Toxicity Reduction Evaluation Guidance for Municipal Waste-water Treatment
Plants. EPA/833B-99/002. U.S. Environmental Protection Agency, Office of Wastewater Management, Washington, DC.
.
2 U.S. Environmental Protection Agency. 2001. Clarifications Regarding Toxicity Reduction and Identification Evaluations in the
National Pollutant Discharge Elimination System Program. U.S. Environmental Protection Agency, Office of Wastewater
Management and Office of Regulatory Enforcement, Washington, DC. .
3 U.S. Environmental Protection Agency. 1989. Generalized Methodology for Conducting Industrial Toxicity Reduction
Evaluations (TREs). EPA-600/2-88-070. U.S. Environmental Protection Agency, Water Engineering Research Laboratory,
Cincinnati, OH. Publication available on NEPIS Website .
5 U.S. Environmental Protection Agency. 1992. Toxicity Identification Evaluation: Characterization of Chronically Toxic
Effluents, Phase I. EPA-600/6-91-005F. U.S. Environmental Protection Agency, Environmental Research Laboratory, Duluth,
MN. .
6 U.S. Environmental Protection Agency. 1993. Methods for Aquatic Toxicity Identification Evaluations: Phase II Toxicity
Identification Procedures for Samples Exhibiting Acute and Chronic Toxicity. EPA-600/R-92-080. U.S. Environmental
Protection Agency, Environmental Research Laboratory, Duluth, MN. .
7 U.S. Environmental Protection Agency. 1993. Methods for Aquatic Toxicity Identification Evaluations: Phase III Confirmation
Procedures for Samples Exhibiting Acute and Chronic Toxicity. EPA-600/R-92-081. U.S. Environmental Protection Agency,
Environmental Research Laboratory, Duluth, MN. .
8U.S. Environmental Protection Agency. 1995. GreatLakes Water Quality Initiative Technical Support Document for the
Procedure to Determine Bioaccumulation Factors. EPA-820/B-95-005. U.S. Environmental Protection Agency, Office of
Science and Technology, Washington, DC. Publication available on NEPIS Website as document
820B95005.
U.S. Environmental Protection Agency. 1993. Guidance Manual for Developing Best Management Practices. EPA 833-B-93-
004. U.S. Environmental Protection Agency, Office of Water, Washington, DC. .
Endnotesfor this chapter continued on the next page.
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10 King, Ephraim S. 1992. Order Denying Modification Request With Respect to the Administrator's 1990 Decision inStar-Kist
Caribe, Inc. (NPDES Appeal No. 88-5). U.S. Environmental Protection Agency, Office of Water. Memorandum, May 27,1992.
.
1' Hanlon, James. A. 2007. Compliance Schedules for Water Quality-Based Effluent Limitations in NPDES Permits.
U.S. Environmental Protection Agency, Office of Wastewater Management. Memorandum, May 10,2007.
.
12 U.S. Environmental Protection Agency. 1999. Introduction to the National PretreatmentProgram. EPA-833-B-98-002.
U.S. Environmental Protection Agency, Office of Wastewater Management, Washington, D.C.
.
13U.S. Environmental Protection Agency. 1994. A Plain English Guide to the EPA Part 503 Biosolids Rule. EPA/832/R-93/003.
U.S. Environmental Protection Agency, Office of Wastewater Management, Washington, DC.
.
16 U.S. Environmental Protection Agency. 1994. Land Application of Sewage SludgeA Guide for Land Appliers on the
Requirements of the Federal Standards for the Use or Disposal of Sewage Sludge in 40 CFR Part 503. EPA-831/B-93-002b.
U.S. Environmental Protection Agency, Office of Water, Washington, DC. .
17 U.S. Environmental Protection Agency. 1994. Surface Disposal of Sewage SludgeA Guide for Owner/Operators of Surface
Disposal Facilities on the Monitoring, Record Keeping, and Reporting Requirements of the Federal Standards for the Use or
Disposal of Sewage Sludge in 40 CFR Part 503. EPA-831/B-93-002c. U.S. Environmental Protection Agency, Office of Water,
Washington, DC. Publication available onNEPIS Website .
20 U.S. Environmental Protection Agency. 1992, Rev. 2003. Control of Pathogens and Vector Attraction in Sewage Sludge.
EPA-625/R-92-013. U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC.
.
21 U.S. Environmental Protection Agency. 1995. Combined Sewer Overflows-Guidance for Long-Term Control Plan.
EPA-832/B-95-002. U.S. Environmental Protection Agency, Office of Water, Washington, DC.
.
22 U.S. Environmental Protection Agency. 1995. Combined Sewer Overflows-Guidance for Nine Minimum Controls.
EPA-832/B-95-003. U.S. Environmental Protection Agency, Office of Water, Washington, DC.
.
23U.S. Environmental Protection Agency. 1995. Combined Sewer Overflows-Guidance for Screening and Ranking. EPA-832/B-
95-004. U.S. Environmental Protection Agency, Office of Wastewater Management, Washington, DC.
.
24U.S. Environmental Protection Agency. 1995. Combined Sewer Overflows-Guidance for Monitoring and Modeling. EPA-
832/B-99-002. U.S. Environmental Protection Agency, Office of Water, Washington, DC.
.
25 U.S. Environmental Protection Agency. 1995. Combined Sewer Overflows-Guidance for Financial Capability Assessment and
Schedule Development. EPA-832/B-97-004. U.S. Environmental Protection Agency, Office of Water and Office of Wastewater
Management, Washington DC. .
26U.S. Environmental Protection Agency. 1995. Combined Sewer Overflows-Guidance for Funding Options. EPA-832/B-95-
007. U.S. Environmental Protection Agency, Office of Water, Washington, DC. .
Endnotesfor this chapter continued on the next page.
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U.S. Environmental Protection Agency. 1995. Combined Sewer Overflows-Guidance for Permit Writers. EPA-832/B-95-008.
U.S. Environmental Protection Agency, Office of Water, Washington, DC. .
28 U.S. Environmental Protection Agency. 2001. Combined Sewer Overflows-Guidance: Coordinating Combined Sewer
Overflow (CSO) Long-Term Planning with Water Quality Standards Reviews. EPA-833/R-01-002. U.S. Environmental
Protection Agency, Office of Water, Washington, DC. .
29 U.S. Environmental Protection Agency. 2004. Report to Congress on the Impacts and Control ofCSOs and SSOs. EPA 833-R-
04-001. U.S. Environmental Protection Agency, Office of Water, Washington, DC. .
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CHAPTER 10. Standard Conditions of NPDES Permits
This chapter describes standard conditions, sometimes called boilerplate conditions, that must be
incorporated in National Pollutant Discharge Elimination System (NPDES) permits. Standard conditions,
specified in Title 40 of the Code of Federal Regulations (CFR) 122.41 and 122.42, play an important
supporting role to effluent limitations, monitoring and reporting requirements, and special conditions
because they delineate various legal, administrative, and procedural requirements of the permit. Standard
conditions cover various topics, including definitions, testing procedures, records retention, notification
requirements, penalties for noncompliance, and other permittee responsibilities. The conditions provided
in § 122.41 apply to all types and categories of NPDES permits and must be included in all permits (see
§ 123.25 for applicability to state NPDES permits). The conditions provided in § 122.42 apply only to
certain categories of NPDES facilities. Any permit issued to a facility in one of the categories listed in
§ 122.42 must contain the additional conditions, as applicable.
The use of standard conditions helps ensure uniformity and consistency of all NPDES permits issued by
authorized states or the U.S. Environmental Protection Agency (EPA) Regional Offices. Permit writers
need to be aware of the contents of the standard conditions because it might be necessary to explain
portions of the conditions to a discharger. The permit writer should keep abreast of any changes in EPA's
standard conditions set out in §§ 122.41 and 122.42. According to § 122.41, standard conditions may be
incorporated into a permit either expressly (verbatim from the regulations) or by reference to the
regulations. It generally is preferable for permit writers to attach the standard conditions expressly
because permittees might not have easy access to the regulations. Some states have developed an
attachment for NPDES permits that includes the federal standard conditions.
10.1 Types of Standard Conditions
A brief summary of the § 122.41 standard conditions that must be included in all types of NPDES permits
follows:
Duty to Comply § 122.41(a): The permittee must comply with all conditions of the permit.
Noncompliance is a violation of the Clean Water Act (CWA) and is grounds for enforcement
action, changes to or termination of the permit, or denial of a permit renewal application.
Duty to Reapply § 122.41(b): A permittee wishing to continue permitted activities after the
permit expiration date must reapply for and obtain a new permit.
Need to Halt or Reduce Activity not a Defense § 122.41(c): The permittee may not use as a
defense in an enforcement action the reasoning that halting or reducing the permitted activity is
the only way to maintain compliance.
Duty to Mitigate § 122.41(d): The permittee is required to take all reasonable steps to prevent
any discharge or sludge use or disposal in violation of the permit that has a reasonable likelihood
of adversely affecting human health or the environment.
Proper Operation and Maintenance § 122.41(e): The permittee must properly operate and
maintain all equipment and treatment systems used for compliance with the terms of the permit.
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The permittee must provide appropriate laboratory controls and quality assurance procedures.
Operation of backup systems is required only when needed to ensure compliance.
Permit Actions § 122.41(f): The permit may be modified, revoked and reissued, or terminated
for cause. A request by the permittee for a permit modification, revocation or reissuance,
termination, or a notification of planned changes or anticipated noncompliance does not suspend
the permittee's obligation to comply with all permit conditions.
Property Rights § 122.41(g): The permit does not convey any property rights of any sort, or any
exclusive privilege.
Duty to Provide Information § 122.41(h): The permittee must furnish, within a reasonable time,
any information needed to determine compliance with the permit or to determine whether there is
cause to modify, revoke and reissue, or terminate the permit. The permittee also must furnish, on
request, copies of records that must be kept as required by the permit.
Inspection and Entry § 122.41(i): The permittee must, upon presentation of valid credentials by
the Director or his or her representative, allow entry into the premises where the regulated activity
or records are present. The Director must have access to and be able to make copies of any
required records; inspect facilities, practices, operations, and equipment; and sample or monitor at
reasonable times.
Monitoring and Records § 122.41(j): Samples must be representative of the monitored activity.
The permittee must retain records for 3 years (5 years for sewage sludge activities) subject to
extension by the Director. Monitoring records must identify the sampling dates and personnel, the
sample location and time, and the analytical techniques used and corresponding results.
Wastewater and sludge measurements must be conducted in accordance with Parts 136 or 503 or
other specified procedures. Falsification of results is a violation under the CWA.
Signatory Requirement § 122.41(k): The permittee must sign and certify applications, reports,
or information submitted to the Director in accordance with the requirements in § 122.22.
Knowingly making false statements, representations, or certifications is punishable by fines or
imprisonment.
Planned Changes § 122.41(1)(1): Notice must be given to the Director as soon as possible of
planned physical alterations or additions to the facility (or both) that could meet the criteria for
determining whether the facility is a new source under § 122.29(b); result in changes in the nature
or quantity of pollutants discharged; or significantly change sludge use or disposal practices.
Anticipated Noncompliance § 122.41(1)(2): The permittee must give advance notice of any
planned changes that could result in noncompliance.
Permit Transfers § 122.41(1)(3): The permit is not transferable except after written notice to the
Director. The Director may require modification or revocation and reissuance, as necessary.
Monitoring Reports § 122.41(1)(4): Monitoring results must be reported at the frequency
specified in the permit and be reported on a discharge monitoring report (DMR) or forms
provided or specified by the Director for reporting results of monitoring sludge use or disposal
practices. Monitoring for any pollutant that occurs more frequently than is required by the permit
and uses approved test procedures or test procedures specified in the permit must also be
reported. Calculations requiring averaging must use an arithmetic mean unless otherwise
specified in the permit.
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Compliance Schedules § 122.41(1)(5): Reports of compliance or noncompliance or any progress
report must be submitted no later than 14 days following the interim or final compliance date
specified in a compliance schedule.
Twenty-Four Hour Reporting § 122.41(1)(6): The permittee must orally report any
noncompliance that might endanger human health or the environment within 24 hours after
becoming aware of the circumstances. Within 5 days of becoming aware of the circumstances, the
permittee must provide a written submission including a description of the noncompliance and its
cause; the period of noncompliance, including exact dates and times; the anticipated time the
noncompliance is expected to continue (if not already corrected); and steps taken to reduce,
eliminate, or prevent reoccurrence unless the Director waives the requirement. In addition, 24-
hour reporting is required for an unanticipated bypass exceeding effluent limits; an upset
exceeding effluent limits; and a violation of a maximum daily effluent limitation for pollutants
listed in the permit for 24-hour reporting.
Other Noncompliance § 122.41(1)(7): The permittee must report all instances of noncompliance
not reported under other specific reporting requirements at the time monitoring reports are
submitted.
Other Information § 122.41(1)(8): If the permittee becomes aware that it failed to submit any
relevant facts in its application, or submitted incorrect information in its application or other
reports, it must promptly submit such facts or information.
Bypass § 122.41(m): The intentional diversion of wastestreams from any portion of a treatment
facility. Bypass is prohibited unless the bypass does not cause the effluent to exceed limits and is
for essential maintenance to assure efficient operation (no notice or 24-hour reporting is required
in such a case). All other bypasses are prohibited, and the Director of the NPDES program may
take enforcement action against a permittee for a bypass, unless the bypass was unavoidable to
prevent loss of life, personal injury, or severe property damage, there was no feasible alternative,
and the proper notification was submitted.
Upset § 122.41(n): An upset (i.e., an exceptional incident in which there is unintentional and
temporary noncompliance with technology-based effluent limits because of factors beyond the
permittee's control) can be used as an affirmative defense in actions brought against the permittee
for noncompliance. An upset does not include noncompliance to the extent caused by operational
error, improperly designed or inadequate treatment facilities, lack of preventative maintenance, or
careless or improper operation. The permittee (who has the burden of proof to demonstrate that an
upset has occurred) must have operational logs or other evidence that shows
When the upset occurred and its causes.
The facility was being operated properly.
- Proper notification was made.
- Remedial measures were taken.
10.2 Other Standard Conditions
In addition to standard conditions specified in § 122.41 that are applicable to all permittees, § 122.42
includes additional conditions applicable to certain categories of NPDES permits. Below are summaries
of these additional standard conditions applicable to various types of NPDES permits.
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Non-Municipal (Industrial) Permits: Additional standard conditions applicable to non-municipal
permits are found in § 122.42(a) and specify that the permittee must notify the Director as soon as it
knows or has reason to believe that the discharge has or will exceed certain notification levels specified in
§§ 122.42(a)(l) and (2). In addition, § 122.44(f) allows the Director to establish alternate notification
levels upon petition by the permittee or by his or her own initiative.
Publicly Owned Treatment Work (POTW) Permits: Additional standard conditions applicable to
POTWs are found in § 122.42(b). The standard conditions specify that the permittee must provide
adequate notice to the Director of the new introduction of certain pollutants into the POTW from an
indirect discharger and of substantial changes in the volume or character of pollutants introduced into the
POTW. That notice must include information on the quality and quantity of effluent introduced to the
POTW and information on the impact to the quality and quantity of the POTW's effluent.
Municipal Separate Storm Sewer Systems: Additional standard conditions applicable to large, medium
or EPA-designaled municipal separate storm sewer systems are in § 122.42(c). Those standard conditions
require that the permittee submit an annual report addressing the status, and changes to, the stormwater
management program, water quality data and other information specified in §§ 122.42(c)(l)-(6).
Individual Stormwater Permits: Initial permits for discharges composed entirely of stormwater and
permitted under § 122.26(e)(7) must require compliance no later than 3 years after permit issuance.
Concentrated Animal Feeding Operations (CAFO) Permits: The regulations at § 122.42(e) specify
conditions that must be included in all permits for CAFOs.
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CHAPTER 11. NPDES Permit Administration
Previous discussions in this manual focused on the process of developing National Pollutant Discharge
Elimination System (NPDES) permit conditions and effluent limitations. This chapter describes the
administrative process associated with the issuance of an NPDES permit including a discussion of the
other federal laws that might affect the development or issuance of NPDES permits.
11.1 Other Federal Laws Applicable to NPDES Permits
This section addresses other federal laws, besides the Clean Water Act (CWA), that permit writers should
consider when drafting an NPDES permit. The requirements imposed under these statutes only apply to
federal actions (i.e., U.S. Environmental Protection Agency [EPA] issuance of permits). Permits issued by
states authorized to administer the NPDES program are not subject to the requirements of these statutes.
However, many states may have enacted state legislation that is modeled on federal law and, therefore, it
is prudent to review state law in these areas before preparing an NPDES permit.
The following sections briefly discuss the other federal laws and contain links to other websites for more
information. Because these laws are implemented by other federal agencies, many of the links provided
below are to websites outside EPA, and EPA is not responsible for the information provided on those
websites. The NPDES regulations at Title 40 of the Code of Federal Regulations (CFR) 122.49 also
include a discussion of how some of the laws relate to the federal NPDES program. Exhibit 11-1 presents
the other federal laws that are applicable to NPDES permits and includes the legislative citations from the
United States Code (U.S.C.) and the implementing regulations in the CFR.
\ Federal law
Exhibit 11-1 Other federal laws applicable to NPDES permits
Federal
Year agency
Legislative
citations
Implementing
regulations
3 Endangered Species Act (ESA)
I National Environmental Policy Act (NEPA)
I National Historic Preservation Act (NHPA)
I Coastal Zone Management Act (CZMA)
I Wild and Scenic Rivers Act
1 Fish and Wildlife Coordination Act (FWCA)
* Essential Fish Habitat Provisions (EFH)
1973
1969
1992
1972
1968
1934
1996
FWS, NMFS
CEQ
ACHP
NOAA
Various
FWS
NOAA
16 U.S.C. 1531 etseq.
42 U.S.C. 4321 etseq.
16 U.S.C. 470 etseq.
16 U.S.C. 1451 etseq.
16 U.S.C. 1271 etseq.
16 U.S.C. 661 etseq.
16 U.S.C. 1855(b)(2)
50 CFR Part 402 |
40 CFR Part 6 I
36 CFR Part 800 |
15 CFR Part 930 |
36 CFR Part 297 [
50 CFR Part 600 |
ff.f.f
This section discusses procedures intended to protect endangered species that apply only to permits issued
by EPA. The 1973 Endangered Species Act (ESA) .
16 U.S.C. 1531 et seq., was enacted to protect and conserve endangered and threatened species and
critical habitat. The Fish and Wildlife Service (FWS) of the Department of the
Interior and the National Marine Fisheries Service (NMFS) of the National
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Oceanic and Atmospheric Administration (NOAA) within the Department of Commerce (collectively the
Services) share primary responsibility for administration of the ESA.
ESA section 7 requires that federal agencies consult with the Services to ensure that any action
authorized, funded, or carried out by the agencies that could affect a listed species or critical habitat and
to ensure that their actions are not likely to jeopardize the continued existence of any endangered species
or threatened species, or result in the destruction or adverse modification of critical habitat of such
species. The ESA section 7 regulations are in 50 CFR Part 402. FWS/NMFS published the ESA Section 7
Consultation Handbook to address the major
consultation processes pursuant to ESA section 7.
Consultation may be either informal or formal. An informal consultation determines if an action is or is
not likely to adversely affect the species. A formal consultation is required if the findings from the
informal consultation show that there is a likelihood for adverse impacts and evaluates whether the
proposed action is likely to jeopardize the continued existence of the species. It is EPA's responsibility to
ensure that consultation occurs; however, a nonfederal representative (i.e., the discharger) may be
designated for the informal consultation.
On February 22, 2001, EPA entered into a National Memorandum of Agreement (National MO A)
with the Services that outlines the process
for consulting on federally issued NPDES permits. In addition, because consultation is not required for
state-issued permits, the National MOA includes a process for coordinating with the Services on state-
issued permits. EPA permit writers should review the ESA consultation regulations and the ESA section 7
Consultation Handbook, and coordinate with the Region's ESA coordinator (if such a position has been
established in a Region) and the Service office(s) nearest to the site.
11.1.2 National Environmental Policy Act
This section discusses environmental review procedures that apply only when EPA issues permits to new
sources (dischargers subject to New Source Performance Standards). The 1969 National Environmental
Policy Act (NEPA) . 42 U.S.C. 4321 et seq., requires that agencies
perform environmental impact reviews and prepare an Environmental Impact Statement (EIS) for major
federal actions significantly affecting the quality of the human environment [see section 102(2)(C)]. The
President's Council on Environmental Quality (CEQ) coordinates federal
environmental efforts to comply with NEPA.
Within EPA, the Office of Federal Activities under the Office of Enforcement and Compliance Assurance
(OECA) is responsible for EPA's implementation of NEPA . EPA's NEPA
regulations are at 40 CFR Part 6. With respect to NPDES permits, CWA section 511 establishes that only
EPA-issued permits to new sources are subject to NEPA's environmental review procedures before
permit issuance. States may have their own state law versions of NEPA. Federal permit writers should
coordinate efforts with the Office of Federal Activities and document all NEPA activities in the permit
file and fact sheet.
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11.1.3 National Historic Preservation Act Amendments
Section 106 of the 1992 National Historic Preservation Act (NHPA) . 16 U.S.C.
470 etseq., as amended, and implementing regulations 36 CFRPart 800 require the Regional
Administrator, before issuing a license (permit), to identify the area of potential effect of a permitted
discharge and, if historic or cultural resources within that area would be adversely affected by the
discharge, to adopt measures when feasible to mitigate potential adverse effects of the licensed activity
and properties listed or eligible for listing in the National Register of Historic Places.
The Act's requirements are to be implemented in cooperation with State Historic Preservation Officers
. and upon notice to, and when appropriate, in consultation with the Advisory
Council on Historic Preservation . which provides national oversight for the NHPA. A
decision by the B.C. Circuit in 2003 concluded that NHPA consultation is not required for state-issued
permits (NationalMining Ass 'n v. Fowler, 324 F.3d 752 (D.C. Cir. 2003) ).
Federal permit writers should evaluate potential effects of NHPA and submit written documentation of
the evaluation to the State Historic Preservation Office and to the permit file.
11.1.4 Coastal Zone Management Act
The 1972 Coastal Zone Management Act (CZMA) .
16 U.S.C. 1451 et seq., was enacted to manage the nation's coastal zone and is implemented through a
state-federal partnership. Section 307 of the CZMA (16 U.S.C. 1456 and 15 CFR Part 930) prohibits the
issuance of federal NPDES permits for activities affecting land or water use in coastal zones unless the
permit applicant certifies that the proposed activity complies with the state Coastal Zone Management
Program and the relevant state either concurs with the applicant's certification or the state's concurrence
is conclusively presumed as a result of the state's failure to concur or non-concur. Coastal States,
according to the CZMA, include those states and territories adjacent to the Atlantic, Pacific, or Arctic
oceans; the Gulf of Mexico; or one or more of the Great Lakes. Any of those states that have completed
the development of its management program is required, as a condition of receipt of federal grant money
under the CZMA, to adopt coastal management plans, which designate boundaries, identify areas of
particular concern, and establish inventories of permitted uses and enforcement policies. Beach access,
emergency planning, and erosion control also must be addressed in such plans.
The Office of Ocean and Coastal Resource Management . which is part
of NOAA within the Department of Commerce, oversees the CZMA. The CZMA implementing
regulations are at 15 CFR Part 930. EPA and other federal agencies must coordinate their activities on
coastal lands with state CZMA plans. Federal permit writers should document all activities relating to
CZMA in the permit file.
11.1.5 Wild and Scenic Rivers Act
The 1968 Wild and Scenic Rivers Act (WSRA) . 16 U.S.C. 1271 et
seq., established a National Wild and Scenic Rivers System (System) and prescribed the process by which
additional rivers may be added to this System. Rivers may be added by act of Congress [WSRA section
2(a)(i)] or by the Secretary of the Interior at the initiative of a state governor [WSRA section 2(a)(ii)].
Under WSRA section 7(a), EPA is prohibited from assisting, by license or otherwise, in the construction
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of any water resources project that would have a direct and adverse effect on the values for which a
national wild and scenic river was established. The WSRA regulations are codified at 36 CFR Part 297.
Federal permit writers should verify whether the receiving water is part of the System and document all
activities related to the Act in the permit file and fact sheet. For detailed explanation of WSRA section 7,
refer to Wild and Scenic Rivers Act: Section 7 . a technical report
of the Interagency Wild and Scenic Rivers Coordinating Council. Permit writers may also refer to
Water Quantity and Quality as Related to the Management of Wild and Scenic Rivers
. a technical report of the Interagency Wild and Scenic Rivers
Coordinating Council.
11.1.6 Fish and Wildlife Coordination Act
The 1934 Fish and Wildlife Coordination Act (FWCA) .
16 U.S.C. 661 etseq., requires mitigation for the loss of wildlife habitat due to the construction of federal
water resources projects. The FWCA requires designers of federal dams, reservoirs, and irrigation works
to include the costs and benefits to fish and wildlife when determining the benefit/cost ratio of a project
and requires that EPA and other federal agencies consult with state and federal wildlife and fisheries
agencies to minimize the impacts of the activity on fish and wildlife. The FWCA specifically calls for
ongoing studies by the U.S. Department of the Interior on the effects of domestic sewage and industrial
wastes on fish and wildlife (16 U.S.C. 665).
No implementing regulations directly related to the FWCA and NPDES permits exist. However, the FWCA
describes actions taken or compelled by the affected federal agencies. The Water Resources Development
under the Fish and Wildlife Coordination Act manual provides the
FWS guidance on implementing the FWCA. Federal permit writers should note any FWCA consultation
activities in the permit file.
11.1.7 Essential Fish Habitat Provisions
The 1996 Essential Fish Habitat (EFH) provisions of the Magnuson-Stevens Fishery Conservation and
Management Act (Magnuson-Stevens Act or MSA) promote the protection of essential fish habitat in any
federal action authorized, funded, or undertaken, or proposed to be authorized, funded, or undertaken, by
such agency that might adversely affect such habitat identified under the MSA [16 U.S.C. 1855(b)(2)].
The MSA requires that federal agencies, such as EPA, consult with the NMFS for any EPA-issued
permits that might adversely affect essential fish habitat identified under the MSA. The regulations
applicable to federal agencies' coordination and consultation under the MSA are codified at 50 CFR
600.905 through 600.930, and other EFH information can be found on the NMFS EFH Website
. Federal permit writers should note any EFH determinations
and consultation activities in the permit file.
11.2 Documentation for Development of the Draft Permit
EPA regulations at 40 CFR 124.2 define a draft permit as a document that indicates the Director's
tentative decision to issue or deny, modify, revoke and reissue, terminate, or reissue a permit. After the
permit is issued, the fact sheet and supporting documentation (administrative record) are the primary
support for defending the permit in the administrative appeals process. Documenting the permit requires
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the permit writer to be organized and logical throughout the permit development process. Some of the
content of the fact sheet and administrative record is specified by federal and state regulation, and the
remainder is dictated by good project management. Permit writers should recognize the importance of
Developing a thorough permit in a logical fashion.
Meeting legal requirements for preparation of an administrative record, fact sheet, and statement
of basis.
Substantiating permit decisions and providing a sound basis for the derivation of permit terms,
conditions, and limitations if challenges are made.
Establishing a permanent record of the basis of the permit for use in future permit actions.
Exhibit 11-2 presents reasons for good documentation in the permit file and fact sheet.
Exhibit 11-2 Reasons for good documentation
Streamlines the permit reissuance/ compliance monitoring process
Establishes a permanent record of the basis for the permit
Explains the legal and technical basis of the permit
Provides a sound basis for future modifications and permits
Requires the permit writer to be organized and logical throughout permit development process
Exhibits 11-3 and 11-4 provide flow diagrams of the NPDES permit administrative process. In general,
the administrative process includes the following:
Documenting all permit decisions.
Coordinating EPA and state review of the draft (or proposed) permit.
Providing public notice, conducting hearings (if appropriate), and responding to public
comments.
Defending the permit and modifying it (if necessary) after issuance.
Note that Exhibit 11-3 provides the general framework for the administrative process where EPA is the
NPDES permitting authority and Exhibit 11-4 provides a typical framework for the administrative process
where a state is the permitting authority. State requirements need not be identical to federal regulatory
requirements, provided they are at least as stringent. Some authorized states have slightly different
processes for developing and issuing NPDES permits. The same holds true for the appeal process. This
manual presents EPA's procedure; state procedures for NPDES permit hearings and appeals vary
according to state law.
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Exhibit 11-3 Administrative process for EPA-issued NPDES permits
No State CWA
Section 401
Certification
Denied
Develop draft permit limits and conditions
Prepare fact sheet (or statement of basis)
Prepare administrative record
i
r
State review of draft permit
and fact sheet (or statement of basis)
State CWA Section
401 Certification
Public notice (opportunity for public comment)
Significant,
Widespread,
Public Interest
Public Hearing
Prepare
final permit,
fact sheet, and admin
1
record
,
J
Issue final permit
1
Petition for Environmental Appeals Board Review
Granted
Environmental Appeals
Board reviews petition and
response and, possibly,
additional written and oral
documents
1
Environmental Appeals Board
decision
Final Agency action
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Exhibit 11-4 Typical administrative process for state-issued NPDES permits*
Significant EPA
Comments/
Objection
Develop draft permit limits and conditions
Prepare fact sheet (or statement of basis)
Prepare administrative record (if required)
Public notice (opportunity for public comment)
EPA review of draft permit
and fact sheet (or statement of basis)**
No EPA Comments
Prepare final permit, fact sheet, and admin, record
Issue final permit
Significant,
Widespread,
Public Interest
Public Hearing
Denied
Petition for State Administrative Appeals Board
Review
Final Agency action
State statutes and regulations govern the specific steps of the state administrative process,
which may differ from the process outlined in this exhibit.
' Under State/EPA MOA, EPA may review draft or proposed permit.
Granted
State Administrative Appeals
Board reviews petition and
response and, possibly,
additional written and oral
documents
State Administrative Appeals
Board decision
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11.2.1
The administrative record should be considered the foundation that supports the NPDES permit. If EPA
issues the permit, the contents of the administrative record are prescribed by regulation, with § 124.9
identifying the required content of the administrative record for a draft permit and § 124.18 describing the
requirements for final permits. Regardless of whether a state or EPA issues the permit, all supporting
materials must be made available to the public at any time and may be examined during the public
comment period and any subsequent public hearing. The importance of maintaining the permit records in
a neat, orderly, complete, and retrievable form cannot be over emphasized. The record allows personnel
from the permitting agency to reconstruct the justification for a given permit and defend the permit during
any legal proceedings regarding the permit.
The administrative record for a draft permit consists, at a minimum, of the specific documents shown in
Exhibit 11-5. Materials that are readily available in the permit issuing office or published material that is
generally available do not need to be physically included with the record as long as they are specifically
referred to in the fact sheet or statement of basis. If EPA issues a draft permit for a new source, the
administrative record should include any EISs or Environmental Assessments (EAs) performed in
accordance with § 122.29(c).
Exhibit 11-5 Elements of the administrative records for a draft permit
Permit application and supporting data
Draft permit .
Statement of basis or fact sheet I
I
All items cited in the statement of basis or fact sheet, including calculations used to derive the I
permit limitations I
Meeting reports I
Correspondence with the applicant and regulatory personnel I
I
All other items in the supporting file I
For new sources, any EA, draft/final EIS, or other such background information, such as a j
Finding of No Significant Impact (only applies if EPA issues the permit)
The administrative record should include all meeting reports and correspondence with the applicant and
other regulatory agency personnel, trip reports, and records of telephone conversations. All
correspondence, notes, and calculations should be dated and indicate the name of the writer and all other
persons involved. Because correspondence is subject to public scrutiny, references or comments that do
not serve an objective purpose should be avoided. Finally, the presentation of calculations and
documentation of decisions should be organized in such away that they can be reconstructed and the
logic supporting the calculation or decisions can easily be found.
11,2,2
A fact sheet is a document that briefly sets forth the principal facts and the significant factual, legal,
methodological, and policy questions considered in preparing the draft permit. When the permit is in the
draft stage, the fact sheet and supporting documentation serve to explain the rationale and assumptions
used in deriving the limitations to the discharger, the public, and other interested parties.
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The NPDES regulations at § 124.8(a) stipulate that every EPA and state-issued permit must be
accompanied by a fact sheet if the permit
Involves a major facility or activity.
Incorporates a variance or requires an explanation under § 124.56(b) (toxic pollutants, internal
waste stream, and indicator pollutants and for privately owned waste treatment facilities).
Is an NPDES general permit.
Is subject to widespread public interest.
Is a Class I sludge management facility.
Includes a sewage sludge land application plan.
A well-documented rationale for all permit decisions reduces the work necessary to reissue a permit by
eliminating conjecture concerning the development of those permit conditions that are being carried
forward to the next permit. That is also true if a modification is initiated during the life of the permit. The
required contents of a fact sheet, as specified in §§ 124.8 and 124.56, are listed in Exhibit 11-6.
Exhibit 11-6 Required elements of a fact sheet
Required element
Regulatory
citation
(40 CFR)
General facility information
Description of the facility or activity
Sketches or a detailed description of the discharge location
Type and quantity of waste/pollutants discharged
§124.8
§ 124.56
§124.8
Summary rationale of permit conditions
Summary of the basis for the draft permit conditions
References to the applicable statutory or regulatory provisions
References to the administrative record
§124.8
Detailed rationale of permit conditions
Explanation and calculation of effluent limitations and conditions
Specific explanations of
- Toxic pollutant limitations
- Limitations on internal wastestreams
- Limitations on indicator pollutants
- Case-by-case requirements
- Decisions to regulate non-publicly owned treatment works (POTWs) under a separate
permit
For EPA-issued permits, the requirements of any state certification
For permits with a sewage sludge land application plan, a description of how all required
elements of the land application plan are addressed in the permit
Reasons why any requested variances do not appear justified, if applicable
§ 124.56
§124.8
Administrative Requirements
A description of the procedures for reaching a final decision on the draft permit, including
- Public comment period beginning and ending dates
- Procedures for requesting a hearing
- Other procedures for public participation
Name and telephone number of the person to contact for additional information
§124.8
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The fact sheet should include detailed discussions of the development of permit limitations for each
pollutant, including the following:
Calculations and assumptions related to production and flow.
Type of limitations (i.e., limitations based on secondary treatment standards, effluent limitations
guidelines and standards (effluent guidelines), case-by-case determinations, or water quality
standards).
Whether the effluent guidelines used were Best Practicable Control Technology Currently
Available (BPT), Best Available Technology Economically Achievable (BAT), Best
Conventional Pollutant Control Technology (BCT), or New Source Performance Standards
(NSPS).
The water quality standards or criteria used.
Whether any parameters were used as indicators for other pollutants.
Citations to appropriate wasteload allocation or total maximum daily load studies, guidance
documents, other references.
Often, decisions to include certain requirements lead to a decision to exclude other requirements. It is just
as important to keep a thorough record of items that were not included in the draft permit as it is to keep a
record of included items. Such records might include the following:
Why were secondary treatment standards, case-by-case determinations, or effluent guidelines
used as the basis for final effluent limitations rather than water quality standards (i.e.,
demonstrate that the limitations checked to see that water quality standards would be attained)?
Why was biomonitoring not included?
Why were pollutants that were reported as present in the permit application not specifically
limited in the permit?
Why is a previously limited pollutant no longer limited in the draft permit?
Finally, the fact sheet should address the logistics of the permit issuance process, including the beginning
and ending dates of the public comment period, procedures for requesting a hearing, and other means of
public involvement in the final decision.
A statement of basis, as described in § 124.7, is required for EPA-issued permits that are not required to
have a fact sheet. A statement of basis describes the derivation of the effluent limitations and the reasons
for special conditions. However, a prudent permit writer will develop the detailed rationale required in a
fact sheet for any permit that includes complex calculations or special conditions (e.g., case-by-case
effluent limitations based on best professional judgment [BPJ]) even if a fact sheet is not required by
regulation.
11.3 Items to Address before Issuing a Final Permit
This section describes the public participation activities that must be conducted in the permit issuance
process. These include providing public notices, collecting and responding to public comments, and
holding public hearings as necessary.
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The public notice is the vehicle for informing all interested parties and members of the general public of
the contents of a draft NPDES permit or other significant actions with respect to an NPDES permit or
permit application. The basic intent of this requirement is to ensure that all interested parties have an
opportunity to comment on significant actions of the permitting agency with respect to NPDES permits.
The exact scope, required contents, and methods for effecting public notices are found in § 124.10. The
NPDES permit-related actions for which public notice is required are shown in Exhibit 11-7.
Exhibit 11-7 Actions for which public notice is required
Tentative denial of an NPDES permit application (not necessarily applicable to state programs)
Preparation of a draft NPDES permit, including a proposal to terminate a permit
Scheduling of a public hearing
An appeal has been granted by the Environmental Appeals Board
Major permit modifications (after permit issuance)
New Source determinations (EPA only)
The permit writer should be particularly concerned with the first three items in Exhibit 11-7. It is
important to note that no public notice is required when a request for a permit modification, revocation,
reissuance, or termination is denied.
Public notice of NPDES permit-related activities should be provided using the following methods:
For major permits, publication of a notice in daily or weekly newspaper within the area affected
by the facility or activity.
For general permits issued by EPA, publication in the FR.
For all permits, direct mailing to various interested parties. This mailing list should include the
following:
The applicant.
- Any interested parties on the mailing list.
- Any other agency that has issued or is required to issue a Resource Conservation and
Recovery Act (RCRA), Underground Injection Control (UIC), Prevention of Significant
Deterioration (PSD) (or other permit under the Clean Air Act), NPDES, CWA section 404,
sludge management, or ocean dumping permit under the Marine Research Protection and
Sanctuaries Act for the same facility or activity.
- Federal and state agencies with jurisdiction over fish, shellfish, and wildlife resources and
over coastal zone management plans, the Advisory Council on Historic Preservation, State
Historic Preservation Officers, including any affected states and tribes.
State agencies conducting area-wide and continuing planning under CWA sections 208(b)(2),
208(b)(4) or 303(e) and the FWS, NMFS, and the U.S. Army Corps of Engineers.
Users identified in the permit application of a privately owned treatment work.
- Persons on any mailing lists developed by including those who request inclusion in writing
and persons solicited for area lists from participants in past permit proceedings in the area.
- Any local government having jurisdiction over the locality of the facility.
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A public notice must contain the information shown in Exhibit 11-8.
Exhibit 11-8 Contents of the public notice
Name and address of the office processing the permit action
Name and address of the permittee or applicant and, if different, of the facility or activity regulated by
the permit
A brief description of the business conducted at the facility or activity described in the permit
Name, address, and telephone number of a contact from whom interested persons can obtain
additional information
A brief description of the comment procedures required, the time and place of any hearing to be held
including procedures to request a hearing
For EPA-issued permits, the location and availability of the administrative record and the times at
which the record will be open for public inspection and a statement that all data submitted by the
applicant is available as part of the administrative record
A description of the location of each existing or proposed discharge point and the name of the
receiving water and the sludge use and disposal practice(s) and the location of each sludge treatment
works treating domestic sewage and use or disposal sites known at the time of permit application
Requirements applicable to a thermal variance under CWA section 316(a)
Requirements applicable to cooling water intake structures under CWA section 316(b)
Any additional information considered necessary
The regulatory agency preparing the permit must provide public notice of the draft permit (including a
notice of intent to deny a permit application), and it must provide at least 30 days for public comment.
The draft permit is usually submitted for public notice after it has undergone internal review by the
regulatory agency that is issuing the permit. State-issued permits typically undergo public notice after
EPA has reviewed and commented on the draft permit. In the special case of those EPA-issued permits
that require an EIS, public notice is not given until after a draft EIS is issued.
Public notice of a draft permit might elicit comments from concerned individuals or agencies. Frequently,
such comments are simply requests for additional information. However, some comments are of a
substantive nature and suggest modifications to the draft permit or indicate that the draft permit is
inappropriate for various reasons. In such cases, commenters must submit all reasonable arguments and
factual material in support of their positions and comments by the close of the public comment period,
and the permitting authority must consider those comments in making final decisions. If the approach is
technically correct and clearly stated in the fact sheet, it will be difficult for commenters to find fault with
the permit. Commenters can always suggest alternatives, however. In addition, an interested party may
also request a public hearing.
To the extent possible, it is desirable to respond to all public comments as quickly as possible. In some
cases, it might be possible to diffuse a potentially controversial situation by providing further explanation
of permit terms and conditions. Additionally, permit writers should also consider notifying commenters
that their comments have been received and are being considered.
The permitting agency must respond to all significant comments, in accordance with § 124.17, at the time
a final permit decision is reached (in the case of EPA-issued permits) or at the same time a final permit is
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actually issued (in the case of state-issued permits). The response should incorporate the following
elements:
Changes in any of the provisions of the draft permit and the reasons for the changes.
Description and response to all significant comments on the draft permit or the permit application
raised during the public comment period or during any hearing.
If any information is submitted during the public comment period raises substantial new questions about
the draft permit, one of the following actions can occur:
A new draft permit with a revised fact sheet or statement of basis is prepared.
A revised statement of basis, a fact sheet, or revised fact sheet is prepared, and the comment
period is reopened.
The comment period is reopened but is limited to new findings only.
If any of those actions is taken, a new public notice, as described earlier, must be given.
For EPA-issued permits, any documents cited in the response to comments must be included in the
administrative record. If new points are raised or new material is supplied during the public comment
period, EPA may document its response to these new materials by adding new materials to the
administrative record.
Any interested party may request a public hearing. The request should be in writing and should state the
nature of the issues proposed to be raised during the hearing. However, a request for a hearing does not
automatically necessitate that a hearing be held. A public hearing should be held when there is a
significant amount of interest expressed during the public comment period or when it is necessary to
clarify the issues involved in the permit decision.
Thus, the decision of whether to hold a public hearing is actually a judgment call. Such decisions are
usually made by someone other than the permit writer. However, the permit writer will be responsible for
ensuring that all the factual information in support of the draft permit is well documented.
Public notice of a public hearing must be given at least 30 days before the public meeting. Public notice
of the hearing may be given at the same time as public notice of the draft permit, and the two notices may
be combined. The public notice of the hearing should contain the following information:
Brief description of the nature and purpose of the hearing, including the applicable rules and
procedures.
Reference to the dates of any other public notices relating to the permit.
Date, time, and place of the hearing.
Scheduling a hearing automatically extends the comment period until at least the close of the hearing
[§ 124.12(c)] and the public comment period may be extended by request during the hearing. Anyone may
submit written or oral comments concerning the draft permit at the hearing. A presiding officer is
responsible for scheduling the hearing and maintaining orderly conduct, including setting reasonable time
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limitations for oral statements. Note that a transcript or recording of the hearing must be available to
interested persons.
11.3.4 Environmental Justice Considerations
Environmental justice (EJ) is the fair treatment and meaningful involvement of all people regardless of
race, color, national origin, or income with respect to the development, implementation, and enforcement
of environmental laws, regulations, and policies. EPA has this goal for all communities and persons
across U.S. It will be achieved when everyone enjoys the same degree of protection from environmental
and health hazards and equal access to the decision-making process to have a healthy environment in
which to live, learn, and work.
In NPDES permits, the public participation process provides opportunities to address EJ concerns by
providing appropriate avenues for public participation, seeking out and facilitating involvement of those
potentially affected, and including public notices in more than one language where appropriate.
11.3.5 EPA and State/Tribal Roles in Reviewing Draft Permits
The CWA and the NPDES regulations include review roles for EPA and for states, tribes, and territories
(states) depending on whether EPA or a state is issuing an NPDES permit.
11.3.5.1 State-issued Permits
Each authorized state administering an NPDES program must transmit to the EPA Region copies of
permit applications received and copies of draft or proposed permits [§ 123.43(a)]. The state and the EPA
Region execute a Memorandum of Agreement (MOA) under § 123.24 that addresses administration and
enforcement of the state's regulatory program. The MOA may specify that EPA will review draft permits
rather than proposed permits [§ 123.44(j)] and specify the classes or categories of permit applications and
draft or proposed permits that the state will send to the EPA Region for review, comment, and, where
applicable, objection. In addition, the MOA specifies classes or categories of permits for which EPA will
waive its right to review the draft or proposed permit. EPA cannot waive its right to review classes or
categories of permits for the following:
Discharges into the territorial seas.
Discharges that could affect waters of a state other than the one in which the discharge originates.
Discharges proposed to be regulated by general permits.
Discharges from a POTW with a daily average discharge exceeding 1 million gallons per day.
Discharges of uncontaminated cooling water with a daily average discharge exceeding 500
million gallons per day.
Discharges from any major discharger or from any NPDES primary industry category.
Discharges from other sources with a daily average discharge exceeding 500,000 gallons per day
(however, EPA may waive review for non-process wastewater).
The MOA provides a period up to 90 days from receipt of a permit during which the EPA Region can
make general comments on, objections to, or recommendations with respect to the permit. If the EPA
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Region objects to a permit, within 90 days of receiving the permit it must transmit to the state a statement
of the reasons for the objection and the actions that the state must take to eliminate the objection
[§ 123.44(a)-(b)]. Specific causes for objection are outlined in the regulations at § 123.44(c). Any
interested party can request a public hearing on an objection by the EPA Region. After such a hearing, the
Region can affirm the objection, modify the terms of the objection, or withdraw the objection and notify
the state of that decision. If the EPA Region does not withdraw the objection, the state then has 30 days to
resubmit a permit revised to meet the objection. If the state does not do so, exclusive authority to issue the
permit passes to the EPA Region. If no public hearing on the objection is held, the time frame for the state
to resubmit a revised permit is 90 days from receipt of the objection.
11.3.5.2 EPA-issued Permits
Permits issued by EPA require an opportunity for state review and certification under CWA section 401.
The state in which a discharge originates or will originate is provided the opportunity to review an
application or a draft permit and certify that the discharge will comply with the applicable water quality
standards. This process also has the benefits of ensuring that state initiatives or policies are addressed in
EPA-issued NPDES permits and promoting consistency between state-issued and EPA-issued permits
where not all permits within the state are issued by the same agency.
Regulations at §§ 124.53 (State Certification) and 124.54 (Special provisions for state certification and
concurrence on applications for CWA section 301(h) variances) describe procedures an EPA permit
writer should follow to obtain state certification. Under CWA section 401(a)(l), EPA may not issue a
permit until a certification is granted or waived. If EPA is preparing the draft permit, state certification
can be accomplished by allowing states to review and certify the application before draft permit
preparation. Under § 124.53, if EPA has not received a state certification by the time the draft permit is
prepared, EPA must send the state a copy of the draft permit along with a notice requesting state
certification.
If the state does not respond within a specified reasonable time, which cannot exceed 60 days, it is
deemed to have waived its right to certify. If the state chooses to certify the draft permit, it may include
any conditions more stringent than those in the draft permit necessary to ensure compliance with the
applicable provisions of the CWA or state law, and must cite the CWA or state law references that
support the changes. In addition, the state is required to include a statement of the extent to which each
condition of the draft permit can be made less stringent without violating the requirements of state law,
including water quality standards. Failure to provide this statement for any condition waives the right to
certify or object to any less stringent condition that might be established during the EPA permit issuance
process. When a permit applicant requests a CWA section 301(h) variance (§ 124.54), the state
certification process is very similar to the process described above. For more on CWA section 301(h)
variances, see section 5.1.3.5 of this manual.
11.3.6 Schedule for Final Permit Issuance
The final permit may be issued after the close of the public notice period and after state certification has
been received (for permits issued by EPA). The public notice period consists of the following:
A 30-day period that gives notice of intent to issue or deny the permit.
A 30-day period advertising a public hearing (if applicable).
Any extensions or reopening of the comment period.
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Final EPA permit decisions are effective immediately upon issuance unless comment were received on
the draft permit, in which case, the effective date of the permit is 30 days after issuance (or a later date if
specified in the permit). In addition, permit decisions will not be immediately effective if review is
requested on the permit under § 124.19. As discussed earlier, any comments that are received must be
answered at the time of final permit issuance (in the case of NPDES states or tribes) or after a final
decision is reached (in the case of EPA). The administrative record for the final permit consists of the
items in Exhibit 11-9.
Exhibit 11-9 Elements of the administrative records for a final permit
All elements for the draft permit administrative record (see Exhibit 11-5)
All comments received during the comment period
The tape or transcript of any public hearing
Any materials submitted at a hearing
Responses to comments
For NPDES new source permits, the draft or final EIS
The final permit
11.4 Administrative Actions after Final Permit Issuance
Once the final permit has been issued, the issuing authority should enter the permit limitations and any
special conditions into the Integrated Compliance Information System for the NPDES program (ICIS-
NPDES) (for more on ICIS-NPDES, see the introduction to this manual and section 11.5.1.1 below).
Entering permit information into ICIS-NPDES will ensure that the facility's performance will be tracked
and the permitting agency will be alerted to the need for corrective action if violations of permit
limitations, terms, or conditions occur.
After final permit issuance, interested parties have opportunities to change the permit through permit
appeals, major/minor permit modifications, termination and revocation, or transfer. Those administrative
procedures are described below.
Throughout the process of developing a permit and during the public notice period, the permit writer
should carefully consider all legitimate concerns of the applicant/permittee and any other interested party.
Nevertheless, there will inevitably be situations in which a permit is issued in spite of the objections of
the permittee or a third party. In such instances, the permittee or interested party can choose to legally
contest or appeal the NPDES permit, as provided in § 124.19. Permit appeals are the process by which
any person that filed comments on the draft permit may contest the final limitations and conditions in a
permit.
Appeals of EPA-issued permits consist of petitioning the Environmental Appeals Board (EAB) for
review. Such review must be requested within 30 days of issuance of the final permit, and challenges
must be limited to issues raised during the draft permit's public comment or hearing processes, although
persons not participating in these processes may seek review of changes in the permit from draft to final
permit. During the appeals process, only those conditions of an existing permit that are being contested
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are stayed. Within a reasonable time following the filing of the petition for review, the EAB must grant or
deny the petition. Only individual permits may be appealed to the EAB; general permits may be
challenged in court or an individual permit may be sought and appealed.
Many states have similar administrative appeal procedures designed to resolve challenges to the
conditions of a permit. For the sake of convenience, such procedures, which could be known by different
names (e.g., evidentiary hearing, administrative appeal), are hereafter permit appeals. Permit writers will,
from time to time, be involved in permit appeals and will need to address the types of issues discussed
below.
Aside from preparing the administrative record and notices, the permit writer might not be involved in the
procedural matters relating to permit appeals. All requests for permit appeals are coordinated through the
office of the EPA Regional Counsel or the appropriate state legal counsel. The permit writer's first
involvement with the appeals process will likely come as a result of designation of the appeals staff, and
his or her role will be limited to that of a technical advisor to legal counsel and, where a state uses an
evidentiary hearing procedure, possibly a witness.
11.4.1.1 Deposition and Testimony
In a state hearing procedure, a permit writer might be required to give a deposition during which the
appellant attorney conducts the questioning that would otherwise occur in the hearing. The deposition is
transcribed and presented as evidence. The appellant attorney may ask some of the same questions at the
hearing.
To prepare for a deposition and testimony, the permit writer should first consult with his or her general
counsel to become familiar with laws, regulations, and policies that could affect the permit. The permit
writer should also be thoroughly familiar with the technical basis for the permit conditions. For example,
if final effluent limitations are based on water quality standards, the permit writer should thoroughly study
the applicable water quality standards, water quality models, and procedures used to develop the effluent
limitations and be prepared to defend all assumptions and decisions made in the effluent limitation
calculations. For case-by-case limitations based on BPJ, the permit writer should carefully review all
applicable data and procedures used to calculate the effluent limitations and should be sure that the
information on which case-by-case limitations are based is unimpeachable, the limitations were derived
from the data in a logical manner in accordance with established procedures, and the limitations are
technically sound and meet applicable standards for economic reasonableness.
A permit appeal before the EAB relies on the information presented in the petitions and briefs, and
possibly includes oral argument, but typically does not use depositions and direct testimony.
11.4.1.2 The Permit Writer's Role in the Appeals Process
As technical advisor to legal counsel, the permit writer's most important function is to develop support
for contested permit conditions. A permit writer should not attempt to support technically indefensible
conditions. Contested permit conditions that are not technically defensible and are not based on any legal
requirement should be brought to counsel's attention, with advice that EPA or the state withdraw those
conditions.
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The second most important advisory function of the permit writer is assisting counsel in identifying
weaknesses in the appellant's arguments. That process could include developing questions for cross-
examination of opposing witnesses in a state permit appeal that involves a hearing. Questions should be
restricted to the subject material covered by the witness' direct testimony and should be designed to elicit
an affirmative or negative response, rather than an essay-type response.
Finally, the permit writer should remember that when a person petitions for EAB review or requests a
hearing for a state-issued permit, the permit writer should refrain from any discussion about the case
without first consulting with legal counsel.
In the role of technical advisor or witness, the permit writer should do the following:
Cultivate credibility.
Never imply or admit weakness in his or her area of expertise.
Never attempt to testify about subjects outside his or her area of expertise.
Always maintain good communication with counsel.
The EAB generally will attempt to resolve permit appeals in the initial stage of granting review. If that is
not possible, the EAB conducts formal review of the contested conditions and publishes a written opinion
(an Environmental Administrative Decision). The result of an EAB or state permit appeal might be relief
from certain permit conditions, validation or strengthening of contested permit conditions, or a
combination of these two outcomes. Under certain circumstances, decisions of the EAB can be appealed
in federal court. Authorized state's permit appeal procedures typically provide for further appeal of
administrative decisions regarding contested permit conditions in state court when all administrative steps
have been fulfilled.
11.4.2 Modification or Revocation and Reissuance of Permits
In most cases, a permit will not need to be modified (or revoked and reissued) during the term of the
permit if the facility can fully comply with permit conditions. However, under certain circumstances, it
might be necessary to modify the permit before its expiration date. A permit modification could be
triggered in several ways. For example, a representative of the regulatory agency might inspect the
facility and identify a need for the modification (i.e., the improper classification of an industry), or
information submitted by the permittee might suggest the need for a change. Of course, any interested
person may make a request for a permit modification.
Modifications differ from revocations and reissuance. In a permit modification, only the conditions
subject to change are reconsidered while all other permit conditions remain in effect. Conversely, the
entire permit could be reconsidered when it is revoked and reissued.
Except where the permittee requests or agrees, permit modifications are limited to specific causes
identified in §§ 122.62(a) and 122.62(b) and summarized in Exhibit 11-10. Most NPDES permit
modifications require EPA or the state to conduct the public notice and participation activities of Part 124,
similar to the issuance or reissuance of the permit; however, only those specific conditions being modified
are open to review and comment. The permitting authority may revoke and reissue a permit during its
term for the causes identified in § 122.62(b) (i.e., the final two bulleted items in Exhibit 11-10).
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Exhibit 11-10 Causes for permit modification
Alterations: When there are material and substantial alterations or changes to the permitted facility or activity
occur that justify new conditions that are different from the existing permit.
New information: When information is received that was not available at the time of permit issuance.
New regulations: Under limited circumstances, when standards or regulations on which the permit was based
have been changed by the modification, withdrawal or promulgation of amended standards or regulations or by
judicial decision.
Compliance schedules: To modify the compliance schedule when good cause exists, such as an act of God,
strike, or flood.
Variance requests: When requests for variances or fundamentally different factors are filed within the specified
time but not granted until after permit issuance.
Toxics: To insert CWA section 307(a) toxic effluent standard or prohibition.
Reopener: Conditions in the permit that require it to be reopened under certain circumstances.
Net limits: Upon request of a permittee who qualifies for effluent limitations on a net basis under § 122.45(g) or
when a permittee is no longer eligible for net limitations, as provided in § 122.45(g)(1)(ii).
Pretreatment: As necessary under § 403.8 (e) to put a compliance schedule in place for the development of a
pretreatment program or to change the schedule for program development.
Failure to notify: Upon failure of an approved state to notify another state whose waters may be affected by a
discharge from the approved state.
Non-limited pollutants: When the level of any pollutant that is not limited in the permit exceeds the level that
can be achieved by the technology-based treatment requirements appropriate to the permit.
Notification levels: To establish notification levels for toxic pollutants as provided in §122.44(f).
Compliance schedules for innovative or alternative facilities: To modify the compliance schedule in light of
the additional time that might be required to construct such a facility.
Small municipal separate storm sewer system (MS4) minimum control measures: For a small MS4 to
include required minimum control measures when the permit does not include such measure(s) based on the
determination that another entity was responsible for implementation and the other entity fails to fulfill its
responsibility to implement such measure(s).
Technical mistakes: To correct technical mistakes or mistaken interpretations of law made in developing the
permit conditions.
Failed BPJ compliance: When BPJ technology is installed and properly operated and maintained but the
permittee is unable to meet its limitations, the limitations may be reduced to reflect actual removal; however,
they may not be less than the limitations in the effluent guidelines. If BPJ operation and maintenance costs are
extremely disproportionate to the costs considered in a subsequent effluent guideline, the permittee may be
allowed to backslide to the limitations in the effluent guideline.
Land application plans: When required by a permit condition to incorporate a land application plan for
beneficial reuse of sewage sludge, to revise an existing land application plan, or to add a land application plan.
Cause exists for termination: Cause exists under § 122.64, and the Director determines that modification is
appropriate.
Notification of proposed transfer: Director may modify the permit upon receipt of ownership transfer
notification.
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There are certain minor modifications that, upon consent of the permittee, may be processed by the
permitting authority without following the procedures for public notice in Part 124. Minor modifications
are generally non-substantive changes (e.g., typographical errors) and are exempt from the administrative
procedures; that is, a draft permit and public review are not required. The specific permit changes that can
be processed as minor modifications, described in § 122.63, are to
Correct typographical errors.
Incorporate more frequent monitoring or reporting.
Revise an interim compliance date in the schedule of compliance, provided the new date is not
more than 120 days after the date specified in the permit and does not interfere with attainment of
the final compliance date requirement.
Allow for a change of ownership, provided no other change is necessary (see section 11.4.4
below).
Change the construction schedule for a new source discharger.
Delete a point source outfall when that outfall is terminated and does not result in discharge of
pollutants from other outfalls except in accordance with permit limits.
Incorporate an approved local pretreatment program.
11.4.3
Situations could arise during the life of the permit that are causes for termination of the permit. Such
circumstances, described in § 122.64(a), include the following:
Noncompliance by the permittee with any condition of the permit.
Misrepresentation or omission of relevant facts by the permittee.
Determination that the permitted activity endangers human health or the environment, and can be
regulated to acceptable levels only by permit modification or termination.
A change in any condition that requires either a temporary or permanent reduction or elimination
of a discharge (e.g., plant closure).
Terminations are used to retract a permittee's privileges to discharge during the permit term. A notice of
intent to terminate a permit is a type of draft permit that follows the same procedures as any draft permit
prepared under § 124.6. Administrative procedures, such as public notice, must be followed in permit
termination proceedings. If a facility with a terminated permit wishes to obtain permit coverage, it would
have to submit an application and apply for a new permit.
The regulations at § 122.64(b) do provide one exception to the more formal permit termination process
described above. Where the entire discharge is permanently terminated by elimination of the flow or by
connection to a POTW (but not by land application or disposal into a well) the permit can be terminated
by notice to the permittee, and the Part 124 administrative process is not required. However, if the
permittee objects to such an expedited termination, the Permitting Authority must then proceed in
accordance with the administrative procedures described above.
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11.4.4 Permit Transfer
Regulatory agencies occasionally receive notification of a change in ownership of a facility covered by an
NPDES permit. Such changes require that a permit be transferred by one of two provisions:
Transfer by modification or revocation: The transfer may be made during the process of a
major or minor permit modification. It may also be addressed by revoking and subsequently
reissuing the permit.
Automatic transfer: A permit may automatically be transferred to a new permittee if three
conditions are met:
- The current permittee notifies the Director 30 days in advance of the transfer date.
The notice includes a written agreement between the old and new owner that contains the
specific date for transfer of permit responsibility, coverage, and liability between them.
The Director of the regulatory agency does not notify the old permittee and the proposed new
permittee that the subject permit will be modified or revoked and reissued.
11.5 Permit Compliance and Enforcement
EPA's OECA is responsible for nationally managing EPA's compliance and enforcement programs for all
media including the CWA and NPDES. EPA uses a mix of tools including compliance assistance,
incentives, and monitoring and enforcement. EPA and state environmental agencies authorized to
administer the NPDES program seek to achieve and maintain a high level of compliance with
environmental laws and regulations. Enforcement provides a powerful incentive for NPDES permittees to
comply, and the way in which an NPDES permit is written directly affects its enforceability. Each permit
must be written clearly and unambiguously so that compliance can be tracked effectively and the permit
can be enforced if violations occur.
The permit writer could become actively involved with the compliance monitoring and enforcement of
the terms and conditions of the NPDES permits that he or she has written. The extent of the permit
writer's involvement will usually depend on the organizational structure of the regulatory agency. Larger,
centrally organized agencies typically have separate personnel responsible for enforcing the terms of
NPDES permits. In other organizations, the individual who writes the permit will also be responsible for
such enforcement activities as discharge monitoring report (DMR) tracking, facility inspections, and
enforcement recommendations. If a civil judicial enforcement action occurs, the permit writer might be
called on to testify regarding the specific requirements of the permit or its basis.
Regardless of a regulatory agency's organizational structure, the permit writer should have an
appreciation for the various aspects of a meaningful NPDES compliance enforcement program. The
following sections address compliance monitoring reviews and inspections and data in the national ICIS-
NPDES (formerly the Permit Compliance System or PCS) database, which provides the basis for
evaluating compliance. This section concludes with a brief description of the enforcement actions
available to facilitate permit compliance. For more information about CWA enforcement, see OECA's
Clean Water Act Enforcement Website .
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11.5.1 Compliance Monitoring
Compliance monitoring is a broad term that includes all activities that federal or state regulatory agencies
take to ascertain a permittee's compliance with the conditions specified in an NPDES permit. Compliance
monitoring data collected as part of the NPDES program are used to evaluate compliance and support
enforcement actions. The process includes receiving, reviewing, and entering data into the ICIS-NPDES
database, conducting on-site inspections, identifying violators, and determining an appropriate response.
A primary function of the compliance monitoring program is to verify compliance with permit conditions,
including effluent limitations and compliance schedules. Compliance verification is achieved through
Compliance review: A review of all written reports and other material relating to the status of a
permittee's compliance.
Compliance inspections: Field-related regulatory activities (i.e., facility inspections, effluent
sampling) to determine compliance.
11.5.1.1 Compliance Review
Compliance and enforcement personnel use two primary sources of information to carry out compliance
reviews:
Permit/compliance files.
The ICIS-NPDES database.
Permit/compliance files include the permit, application, fact sheet, compliance schedule reports,
compliance inspection reports, DMRs, enforcement actions, and correspondence (e.g., summaries of
telephone calls, copies of warning letters). Compliance personnel periodically review that information and
use it to determine if enforcement is necessary and, if so, what level of enforcement is appropriate.
The ICIS-NPDES database is the national database for tracking compliance with
NPDES requirements and is discussed further in this manual's introduction. Information in ICIS-NPDES
includes facility and discharge characteristics, self-monitoring data, compliance schedules, permit
conditions, inspections, and enforcement actions. Permittees are required to submit effluent monitoring
data, and compliance and status information, via Compliance Schedule Reports and DMRs. EPA Regions
and NPDES states enter such information into ICIS-NPDES and evaluate permittees on compliance with
NPDES permit requirements. Inspection and enforcement information is collected and entered by Regions
or authorized states or both. Quarterly, EPA reviews the ICIS-NPDES system data and generates a
quarterly noncompliance report (QNCR) for all major facilities following the requirements of § 123.45.
ICIS-NPDES supports compliance and enforcement actions and assists EPA staff in evaluation and
oversight of the NPDES program. The database also promotes national consistency and uniformity in
permit and compliance evaluations. NPDES permits must be written so that compliance can be tracked
using ICIS-NPDES. Situations might arise in which permit limitations and monitoring conditions are not
initially compatible with ICIS-NPDES entry and tracking. In such cases, the permit writer should alert the
state or EPA Regional staff responsible for entering ICIS-NPDES codes and work with them to resolve
any coding issues. To assist ICIS-NPDES coders in accurately interpreting and entering the permit into
ICIS-NPDES and to assist enforcement personnel in reviewing permittee's self-monitoring data and
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reports in a timely manner, permit writers should follow the compliance inspection procedures discussed
in the next section.
11.5.1.2 Compliance Inspections
Compliance inspections refer to all field-related regulatory activities conducted to determine permit
compliance. Such field activities can include compliance evaluation inspections (non-sampling), sampling
inspections, other specialized inspections, and remote sensing. Certain inspections, such as diagnostic
inspections and performance audit inspections, aid the regulatory agency in evaluating the facility's
problems in addition to providing information to support enforcement action. Biomonitoring inspections
are specifically targeted at facilities with effluent suspected or identified as causing toxicity problems that
threaten the ecological balance of the receiving waters.
Compliance inspections are undertaken to fulfill one or more of the following purposes:
Establish a regulatory presence to deter noncompliance.
Ensure that permit requirements are being met or determine if permit conditions are adequate.
Check the completeness and accuracy of a permittee's performance and compliance records.
Assess the adequacy of the permittee's self-monitoring and reporting program including on-site
laboratory functions.
Determine the progress or completion of corrective action.
Obtain independent compliance data on a facility's discharge.
Evaluate the permittee's operation and maintenance activities.
Observe the status of construction required by the permit.
11.5.2 Quarterly Noncompliance Reports
EPA Regional offices and NPDES states are required by the regulations at § 123.45 to report quarterly on
major facilities that are not in compliance with the terms and conditions of their permit or enforcement
order (i.e., that meet the criteria for reportctble noncompliance [RNC] for effluent limitation, schedules,
and reporting violations).
The regulations in § 123.45 establish requirements for listing facility violations and resulting regulatory
enforcement action on QNCRs. The regulation establishes reporting requirements for violations that meet
specific, quantifiable reporting criteria, as well as for violations that are more difficult to quantify but are
of sufficient concern to be considered reportable. The regulation also specifies the format that the reports
must follow and the schedule for their submission.
Only major facilities that meet RNC criteria must be reported on the QNCR. RNC consists of several
general types of violations as established in § 123.45:
Effluent limitations
Monthly average effluent limitations (see below for more).
Other effluent limitations with water quality or health impacts.
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Schedule: Violations of compliance schedule milestones by 90 days or more.
Reporting: Reports late by 30 days or more.
A violation of any monthly average limitation should be evaluated for magnitude by comparing the
measured amount in the DMRto the product of the monthly average limitation times the Technical
Review Criteria (TRC) for that pollutant or parameter. The TRC is 1.4 for Group I (conventional)
pollutants and 1.2 for Group II (generally toxic) pollutants. Appendix A to Part 123 contains a list of
pollutants in each Group. RNC includes violations of a given Group I or Group II pollutant or parameter
that equals or exceeds the product of the TRC times the monthly average limitation for any 2 or more
months during a 6-month reporting period. RNC also includes violations of a Group I or Group II
parameter by any amount (not necessarily TRC times the limitation or greater) for 4 months during the
6-month reporting period.
A subset of instances of RNC that appear on the QNCR could be noted as significant noncompliance
(SNC). This distinction is used solely for management accountability purposes as a means of tracking
trends in compliance and evaluating the relative timeliness of enforcement response toward priority
violations.
The definition of SNC is not regulatory and can change as the NPDES program evolves to encompass
new enforcement priorities. For example, in September 1995, EPA revised the definition of SNC to
include violations of non-monthly average permit limitations by major facilities. Many permits for
NPDES major facilities lacked required monthly average limitations and, thus, were not evaluated for
SNC violations and follow-up formal enforcement action. The new definition became effective as of
October 1, 1996. EPA's SNC policy is described in the memorandum Revision of NPDES Significant
Noncompliance (SNC) Criteria to Address Violations of Non-Monthly Average Limits1
.
Generally, the designation of SNC indicates a violation is of sufficient magnitude or duration or both to
be considered among EPA's priorities for regulatory review or response. The categories of SNC are
Effluent limitations: The effluent limitation SNC criteria are the same as for QNCR discussed
above.
Schedule: The schedule SNC criteria are the same as for QNCR discussed above.
Reporting: The reporting SNC criteria are the same as for QNCR discussed above.
Order requirements: Violation of requirements in administrative or judicial orders.
The instance of SNC is considered resolved when the SNC criteria are no longer met during the review
period, or when the permittee formerly in SNC exhibits compliance for all 3 months of the most recent 3-
month reporting period. A permittee with SNC violations under a compliance schedule that is meeting its
deadlines for corrective actions is in resolved pending status.
Any major permittee that is listed on the QNCR for two consecutive 3-month reporting periods for the
same instance of SNC (e.g., same outfall point, same parameter, same category of violation) is expected
to return to compliance or to be addressed with an appropriate enforcement action before the reporting
deadline for the second QNCR. If the facility is in SNC after the second QNCR, and no enforcement
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action has been taken, the facility is placed on the Watch List. The Watch List is a management tool that
identifies and tracks facilities with serious violations and no apparent formal enforcement response.
11.5.3
EPA's NPDES compliance and enforcement principles and recommendations are described in the NPDES
Enforcement Management System (EMS)2 . By choosing an appropriate enforcement response to CWA violations, EPA tries to achieve
several goals:
Correction of the violation as soon as possible.
Deterrence of future violations by the same permittee or other permittees.
Equal treatment of the regulated community through use of a uniform approach to selecting
enforcement responses (i.e., similar violations are treated similarly).
Assessment of an appropriate penalty.
Protection of human health and the environment.
Once a facility has been identified as having potential CWA violations, EPA or the NPDES state reviews
the facility's compliance history. The review includes an assessment of the magnitude, frequency, and
duration of violations. The permitting authority identifies significant violations and makes a
determination of the appropriate enforcement response. CWA section 309 authorizes the Agency to bring
civil or criminal action against facilities that discharge pollutants without a permit or discharge in
violation of NPDES permit conditions and judicial penalties up to $32,500 per day per violation.
EPA Regions and authorized states have specific procedures for reviewing self-monitoring and inspection
data and for deciding what type of enforcement action is warranted. EPA recommends an escalating
response to continuing noncompliance. The range of enforcement responses includes the following:
Informal action (e.g., notice of violation [NOV]).
Formal action.
Administrative compliance order.
Administrative order with or without an administrative penalty order (up to $157,500).
Civil judicial action that imposes injunctive relief seeking compliance or penalty or both.
Criminal prosecution.
Considerations when making determinations on the level of the enforcement response include the
following:
The duration of the violation.
The severity of the violation.
The degree of economic benefit obtained through the violation.
Compliance history and previous enforcement actions taken against the violator.
The degree of culpability.
The deterrent effect of the response on similarly situated permittees.
Equally important considerations may include fairness and equity, national consistency, and the integrity
of the NPDES program.
Chapter 11: NPDES Permit Administration 11-25
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September 2010 NPDES Permit Writers' Manual
Citizens can participate in the enforcement process in a number of ways. Under the Freedom of
Information Act, citizens have the right to request certain facility-specific compliance information from
EPA's ICIS-NPDES database. In addition, under NPDES regulations, interested citizens can intervene in
any federal civil judicial action to enjoin any threatened or continuing violation of program requirements
or permit conditions, and to recover civil penalties in court. Citizens also have the opportunity to review
and comment on any proposed consent decree to resolve a state or federal civil judicial enforcement
action.
CWA section 505 allows any citizen to begin a civil judicial enforcement action on his or her own behalf.
In certain circumstances, citizens may not begin suit if EPA or the state is diligently prosecuting a civil or
criminal judicial action or an administrative action to obtain a penalty under CWA section 309(g) or a
comparable provision of state law. Citizens must also give EPA, the state, and the alleged violator
60 days' notice of the alleged violation before beginning a citizen suit.
1 Herman, S.A. 1995. Revision of NPDES Significant Noncompliance (SNC) Criteria to Address Violations of Non-Monthly
Average Limits. U.S. Environmental Protection Agency, Office of Enforcement and Compliance Assurance. Memorandum,
September 21, 1995. .
2 U.S. Environmental Protection Agency. 1989. The Enforcement Management System: National Pollutant Discharge
Elimination System (Clean Water Act). EC-G-1998-1 Ib. U.S. Environmental Protection Agency, Office of Water, Washington,
DC. .
11-26 Chapter 11: NPDES Permit Administration
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Appendix A. Acronyms, Abbreviations and Glossary
This appendix contains two tables for permit writers to more easily navigate through the acronyms and
the terms that are mentioned throughout this manual. The first table, Acronyms and Abbreviations,
provides the full text of the acronyms and abbreviations used throughout and indicates whether they are
defined in the Glossary (the second table), which provides definitions of terms used in the Clean Water
Act and NPDES permit program. It provides a reference to the source of the definitions, where available.
A.1 Acronyms and Abbreviations
Exhibit A-l presents the abbreviations used in the NPDES Permit Writers' Manual.
Acronym or
abbreviation
Exhibit A-1 Acronyms and abbreviations
Full phrase
Glossary
J1Q10
J7Q10
4AAP
JACHP
JACR
AFO
JAML
ASR
AWL
BA
BAT
BCT
BE
BMP
BOD
BOD5
BPJ
IBPT
ICAAP
CAFO
CBOD
CBOD5
CEQ
I CERCLA
ICFR
cfs
ICGP
CMOM
1-day, 10-year Low Flow
7-day, 10-year Low Flow
4-Aminoantipyrine (used for detecting phenolic compounds colorimetrically)
Advisory Council on Historic Preservation
Acute-to-Chronic Ratio
Animal Feeding Operation
Average Monthly Limitation
Alternative State Requirement
Average Weekly Limitation
Biological Assessment
Best Available Technology Economically Achievable
Best Conventional Pollutant Control Technology
Biological Evaluation
Best Management Practice
Biochemical Oxygen Demand
5-day Biochemical Oxygen Demand
Best Professional Judgment
Best Practicable Control Technology Currently Available
Concentrated Aquatic Animal Production
Concentrated Animal Feeding Operation
Carbonaceous Biochemical Oxygen Demand
5-day Carbonaceous Biochemical Oxygen Demand
Council on Environmental Quality
Comprehensive Environmental Response, Compensation and Liabilities Act
Code of Federal Regulations
Cubic Feet per Second
Construction General Permit
Capacity, Management, Operation and Maintenance
|
X
X
X
X
X
X
X
X
X
X
X
X
I
Appendix A. Acronyms, Abbreviations and Glossary
A-l
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September 2010
NPDES Permit Writers' Manual
Acronym or
abbreviation
Exhibit A-1 Acronyms and abbreviations (continued)
Full phrase
Glossary
COD
CSO
CSS
cv
CWA
CWIS
CZMA
DMR
DWO
EA
EAB
EC
EFH
EIS
ELG
EMS
eNOI
EPA
ESA
PDF
PR
FWCA
FWPCA
FWS
GC/MS
gpd
HEM
1C
ICIS
I/I
LA
Ibs/day
LC50
LOEC
LTA
LTCP
MDL
MDL
MEP
ug/L
mg/L
mgd
ML
Chemical Oxygen Demand
Combined Sewer Overflow
Combined Sewer System
Coefficient of Variation
Clean Water Act
Cooling Water Intake Structure
Coastal Zone Management Act
Discharge Monitoring Report
Dry Weather Overflow
Environmental Assessment
Environmental Appeals Board
Effect Concentration
Essential Fish Habitat
Environmental Impact Statement
Effluent Limitations Guidelines or Effluent Guidelines
Enforcement Management System
Electronic Notice of Intent
U.S. Environmental Protection Agency
Endangered Species Act
Fundamentally Different Factors
Federal Register
Fish and Wildlife Coordination Act
Federal Water Pollution Control Act
U.S. Fish and Wildlife Service
Gas Chromatography/Mass Spectroscopy
Gallons per Day
Hexane Extractable Material
Inhibition Concentration
Integrated Compliance Information System
Infiltration/Inflow
Load Allocation
Pounds per Day
Lethal Concentration to 50% of test organisms
Lowest Observed Effect Concentration
Long-Term Average
Long-Term Control Plan
Method Detection Limit
Maximum Daily Effluent Limitation
Maximum Extent Practicable
Micrograms per Liter
Milligrams per Liter
Million Gallons per Day
Minimum Level
X
X
X
X
X
X
X
X
X
y
A-2
Appendix A. Acronyms, Abbreviations and Glossary
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September 2010
NPDES Permit Writers' Manual
Acronym or
abbreviation
Exhibit A-1 Acronyms and abbreviations (continued)
Full phrase
Glossary
MOA
MS4
MSA
MSGP
N/A
NAICS
NEMI
NEPA
NHPA
NMC
NMFS
NMP
NOAA
NOEC
NOI
NOV
NPDES
NRDC
NSCEP
NSPS
NTIS
O&G
OCPSF
OECA
ONRW
OTIS
OW
OWRC
PCS
POTW
PSD
PSES
PSNS
QNCR
RAPP
RCRA
RNC
SIC
SIU
SNC
SOP
SPCC
SS
Memorandum of Agreement
Municipal Separate Storm Sewer System
Magnuson-Stevens Act
Multi-Sector General Permit
Not Applicable
North American Industrial Classification System
National Environmental Methods Index
National Environmental Policy Act
National Historic Preservation Act
Nine Minimum CSO Controls
National Marine Fisheries Service
Nutrient Management Plan
National Oceanic and Atmospheric Administration
No Observable Effect Concentration
Notice of Intent
Notice of Violation
National Pollutant Discharge Elimination System
Natural Resources Defense Council
National Service Center for Environmental Publications
New Source Performance Standards
National Technical Information Service
Oil and Grease
Organic Chemicals, Plastics, and Synthetic Fibers Point Source Category
EPA Office of Enforcement and Compliance Assurance
Outstanding National Resources Waters
Online Tracking Information System
Office of Water
Office of Water Resource Center
Permit Compliance System
Publicly Owned Treatment Works
Prevention of Significant Deterioration
Pretreatment Standards for Existing Sources
Pretreatment Standards for New Sources
Quarterly Noncompliance Report
Refuse Act Permit Program
Resource Conservation and Recovery Act
Reportable Noncompliance
Standard Industrial Classification
Significant Industrial User
Significant Noncompliance
Standard Operating Procedure
Spill Prevention Control and Countermeasure
Suspended Solids
X
X
X
X
X
X
y
Appendix A. Acronyms, Abbreviations and Glossary
A-3
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September 2010
NPDES Permit Writers' Manual
Acronym or
abbreviation
Exhibit A-1 Acronyms and abbreviations (continued)
Full phrase
Glossary
sso
STORE!
SWPPP
TBEL
TCDF
TEC
THC
TIE
TMDL
TOC
TRC
TRE
TRI
TSD
TSS
TTO
TU
TUa
TUc
TWTDS
UAA
UIC
U.S.C.
WET
VGP
WLA
WPD
WQA
WQBEL
WQS
WSRA
Sanitary Sewer Overflow
EPA Storage and Retrieval Database
Stormwater Pollution Prevention Plan
Technology-Based Effluent Limit(s)
Tetrachlorodibenzofuran
Transportation Equipment Cleaning Point Source Category
Total Hydrocarbons
Toxicity Identification Evaluation
Total Maximum Daily Load
Total Organic Carbon
Technical Review Criteria
Toxicity Reduction Evaluation
Toxic Release Inventory
Technical Support Document [for Water Quality-based Toxics Control]
Total Suspended Solids
Total Toxic Organics
Toxic Units
Toxic Units- Acute
Toxic Units - Chronic
Treatment Works Treating Domestic Sewage
Use Attainability Analysis
Underground Injection Control
United States Code
Whole Effluent Toxicity
Vessel General Permit
Waste Load Allocation
EPA Water Permits Division
Water Quality Act of 1987
Water Quality-Based Effluent Limit(s)
Water Quality Standard(s)
Wild and Scenic Rivers Act
x
x I
x
x I
x
X
X
X I
X
x
X I
X
A.2
Exhibit A-2 includes definitions of terms used in the NPDES Permit Writers 'Manual. For terms that have
a definition in the federal regulations, that definition is included with an appropriate citation. The citations
also indicate where this guidance manual has paraphrased or modified the regulatory definitions for
consistency with the format of the glossary. For terms that do not have a regulatory definition, but that are
defined in another published EPA document, the citation to the relevant EPA document is provided.
Note that the definitions provided in the Glossary do not constitute EPA's official use of terms and
phrases for regulatory purposes, and nothing in this document should be construed to alter or supplant any
A-4
Appendix A. Acronyms, Abbreviations and Glossary
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September 2010
NPDES Permit Writers' Manual
other federal document. Official terminology is in the laws and related regulations as published in such
sources as the Congressional Record, Federal Register, and elsewhere.
Term
Exhibit A-2 Glossary
Definition
Citation
401 (a) Certification
A requirement of CWA section 401 (a) that all federally issued
permits be certified by the state in which the discharge occurs.
The state certifies that the proposed permit will comply with
state water quality standards and other state requirements.
1996 U.S. EPA NPDES
Permit Writers' Manual
(1996PWM)
Acute Effect
The effect of a stimulus severe enough to rapidly induce an
effect; in aquatic toxicity tests, an effect generally observed in
96 hours or less is typically considered acute. When referring to
aquatic toxicology or human health, an acute effect is not
always measured in terms of lethality.
1996PWM
Animal Feeding
Operation (AFO)
Lot or facility (other than an aquatic animal production facility)
where the following conditions are met:
Animals (other than aquatic animals) have been, are, or will
be stabled or confined and fed or maintained for a total of 45
days or more in any 12-month period.
Crops, vegetation, forage growth, or post-harvest residues
are not sustained in the normal growing season over any
portion of the lot or facility.
§122.23(b)(1)
Anti-backsliding
In general, a statutory provision that prohibits the renewal,
reissuance, or modification of an existing NPDES permit that
contains effluent limitations, permit conditions, or standards that
are less stringent than those established in the previous permit.
For more information on anti-backsliding, see Chapter 7 of this
manual.
CWA section 402(o)
Antidegradation
A policy developed and adopted as part of a state's water
quality standards that ensures protection of existing uses and
maintains the existing level of water quality where that water
quality exceeds levels necessary to protect fish and wildlife
propagation and recreation on and in the water. This policy also
includes special protection of water designated as Outstanding
National Resource Waters.
Adapted from
1996PWM
Authorized
Program or
Authorized State
A state, territorial, tribal, or interstate NPDES program that has
been approved or authorized by EPA under Part 123.
1996PWM
Average Monthly
Discharge
Limitation
The highest allowable average of daily discharges over a
calendar month, calculated as the sum of all daily discharges
measured during that month divided by the number of daily
discharges measured during that month.
§ 122.2
Average Weekly
Discharge
Limitation
The highest allowable average of daily discharges over a
calendar week, calculated as the sum of all daily discharges
measured during a calendar week divided by the number of
daily discharges measured during that week.
§ 122.2
Best Available
Technology
Economically
Achievable (BAT)
Technology standard established by the CWA as the most
appropriate means available on a national basis for controlling
the direct discharge of toxic and nonconventional pollutants to
navigable waters. BAT limitations in effluent guidelines, in
general, represent the best existing performance of treatment
technologies that are economically achievable within an
industrial point source category or subcategory.
Adapted from
1996PWM
Appendix A. Acronyms, Abbreviations and Glossary
A-5
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NPDES Permit Writers' Manual
Term
Exhibit A-2 Glossary (continued)
Definition
Citation
| Best Conventional
Pollutant Control
Technology (BCT)
E Best Management
Practice (BMP)
Best Practicable
| Control Technology
E Currently Available
I (BPT)
Best Professional
Judgment (BPJ)
Bioassay
Biochemical
E Oxygen Demand
(BOD)
| Biosolids
| Bypass
E Carbonaceous
E Biochemical
E Oxygen Demand
(CBOD)
Categorical
E Industrial User
| (CIU)
Categorical
Pretreatment
Standards
Technology-based standard for the discharge from existing
industrial point sources of conventional pollutants including
BOD, TSS, fecal coliform, pH, oil and grease. The BCT is
established in light of a two-part cost reasonableness test,
which compares the cost for an industry to reduce its pollutant
discharge with the cost to a POTW for similar levels of reduction
of a pollutant loading. The second test examines the cost-
effectiveness of additional industrial treatment beyond BPT.
EPA must find limits which are reasonable under both tests
before establishing them as BCT.
Schedules of activities, prohibitions of practices, maintenance
procedures, and other management practices to prevent or
reduce the pollution of waters of the United States. BMPs also
include treatment requirements, operating procedures, and
practices to control plant site runoff, spillage or leaks, sludge or
waste disposal, or drainage from raw material storage.
The first level of technology standards established by the CWA
to control pollutants discharged to waters of the U.S. BPT
limitations in effluent guidelines are generally based on the
average of the best existing performance by plants within an
industrial category or subcategory.
The method used by permit writers to develop technology-based
NPDES permit conditions on a case-by-case basis using all
reasonably available and relevant data.
A test used to evaluate the relative potency of a chemical or a
mixture of chemicals by comparing its effect on a living
organism with the effect of a standard preparation on the same
type of organism.
A measurement of the amount of oxygen used by the
decomposition of organic material, over a specified time (usually
5 days) in a wastewater sample; it is used as a measurement of
the readily decomposable organic content of a wastewater.
See Sewage Sludge.
The intentional diversion of waste streams from any portion of a
treatment facility. This definition applies to both direct and
indirect discharges.
The biochemical oxygen demand of carbonaceous sources.
This differs from BOD in that BOD measures both nitrogenous
and carbonaceous sources, whereas CBOD excludes
nitrogenous sources (e.g., nitrifying bacteria) from determination
through the addition of a nitrification inhibitor.
An industrial user subject to national categorical pretreatment
standards.
National pretreatment standards , expressed as Pretreatment
Standards for Existing Sources (PSES) or Pretreatment
Standards for New Sources (PSNS), specifying quantities or
concentrations of pollutants or pollutant properties that may be
discharged to a POTW by existing or new industrial users in
specific industrial subcategories established as separate
regulations under the appropriate subpart of 40 CFR chapter I,
subchapter N.
1996PWM
§ 122.2
Adapted from E
1996PWM
1996PWM
1996PWM
1996PWM
I
§122.41(m)(1)(i)and I
§403.17 j
-
1996PWM
Adapted from
§ 403.6
A-6
Appendix A. Acronyms, Abbreviations and Glossary
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NPDES Permit Writers' Manual
Term
Exhibit A-2 Glossary (continued)
Definition
Citation
Chemical Oxygen
Demand (COD)
A measure of the oxygen-consuming capacity of inorganic and
organic matter present in wastewater. COD is expressed as the
amount of oxygen consumed in mg/L. Results do not
necessarily correlate to the biochemical oxygen demand (BOD)
because the chemical oxidant can react with substances that
bacteria do not stabilize.
Adapted from
1996PWM
Chronic Effect
The effect of a stimulus that lingers or continues for a relatively
long period, often one-tenth of the life span or more. The
measurement of a chronic effect can be reduced growth,
reduced reproduction, and such, in addition to lethality.
1996PWM
Clean Water Act
(CWA)
The Clean Water Act is a statute passed by the U.S. Congress
to control water pollution. It was formerly referred to as the
Federal Water Pollution Control Act of 1972 or Federal Water
Pollution Control Act Amendments of 1972 (Public Law 92-500),
33 U.S.C. 1251 et seq., as amended by: Public Law 96-483;
Public Law 97-117; Public Laws 95-217, 97-117, 97-440, and
100-04.
1996PWM
Code of Federal
Regulations (CFR)
A codification of the final rules published daily in the Federal
Register. Title 40 of the CFR contains regulations for the
protection of the environment.
1996PWM
Combined Sewer
Overflow (CSO)
A discharge of untreated wastewater from a combined sewer
system at a point before the headworks of a publicly owned
treatment works. CSOs generally occur during wet weather
(rainfall orsnowmelt). During periods of wet weather, these
systems become overloaded, bypass treatment works, and
discharge directly to receiving waters at designed overflow
points.
1996PWM
Combined Sewer
System (CSS)
A wastewater collection system that conveys sanitary
wastewaters (domestic, commercial and industrial wastewaters)
and stormwater through a single pipe to a publicly owned
treatment works for treatment before discharge to surface
waters.
1996PWM
Compliance
Schedule (or
Schedule of
Compliance)
A schedule of remedial measures included in a permit, including
an enforceable sequence of interim requirements (for example,
actions, operations, or milestone events) leading to compliance
with the CWA and regulations.
§ 122.2
Composite Sample
Sample composed of two or more discrete aliquots (samples).
The aggregate sample will reflect the average water quality of
the compositing or sample period.
Conventional
Pollutants
Pollutants typical of municipal sewage, and for which publicly
owned treatment works typically are designed to remove;
defined by Federal Regulation (§ 401.16) as BOD, TSS, fecal
coliform bacteria, oil and grease, and pH.
1996PWM
Daily Discharge
The discharge of a pollutant measured during a calendar day or
any 24-hour period that reasonably represents the calendar day
for purposes of sampling. For pollutants with limitations
expressed in units of mass, the daily discharge is calculated as
the total mass of the pollutant discharged over the day. For
pollutants with limitations expressed in other units of
measurement, the daily discharge is calculated as the average
measurement of the pollutant over the day.
§ 122.2
Appendix A. Acronyms, Abbreviations and Glossary
A-7
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NPDES Permit Writers' Manual
Term
Exhibit A-2 Glossary (continued)
Definition
Citation
Designated Uses
Those uses specified in water quality standards for each
waterbody or segment whether they are being attained
(§ 131.3). Examples of designated uses include cold and warm
water fisheries, public water supply, and irrigation.
Adapted from
EPA. Terms of
Environment: Glossary,
Abbreviations,
Acronyms.
Development
Document
A report prepared during development of an effluent guideline
by EPA that provides the data and methodology used to
develop effluent guidelines and categorical pretreatment
standards for an industrial category.
Adapted from
1996PWM
Director
The Regional Administrator or the State Director, as the context
requires, or an authorized representative. When there is no
approved state program, and there is an EPA-administered
program, Director means the Regional Administrator. When
there is an approved state program, Director normally means
the State Director. In some circumstances, however, EPA
retains the authority to take certain actions even when there is
an approved state program. (For example, when EPA has
issued an NPDES permit before the approval of a state
program, EPA may retain jurisdiction over that permit after
program approval, see § 123.1.) In such cases, Director means
the Regional Administrator and not the State Director.
§ 122.2
Discharge
Monitoring Report
(DMR)
The EPA uniform national form, including any subsequent
additions, revisions, or modifications for the reporting of self-
monitoring results by permittees. DMRs must be used by
approved states as well as by EPA. EPA will supply DMRs to
any approved state upon request. The EPA national forms may
be modified to substitute the state agency name, address, logo,
and other similar information, as appropriate, in place of EPA's.
§ 122.2
Draft Permit
A document prepared under § 124.6 indicating the Director's
tentative decision to issue, deny, modify, revoke and reissue,
terminate, or reissue a permit. A notice of intent to terminate a
permit, and a notice of intent to deny a permit, as discussed in §
124.5, are types of draft permits. A denial of a request for
modification, revocation and reissuance, or termination, as
discussed in § 124.5, is not a draft permit. A proposed permit is
not a draft permit.
§ 122.2
Effluent Limitation
Any restriction imposed by the Director on quantities, discharge
rates, and concentrations of pollutants which are discharged
from point sources into waters of the United States, the waters
of the contiguous zone, or the ocean.
§ 122.2
Effluent Limitations
Guidelines (Effluent
Guidelines or ELG)
A regulation published by the Administrator under CWA section
304(b) to adopt or revise effluent limitations.
§ 122.2
Existing Uses
Those uses actually attained in the waterbody on or after
November 28, 1975, whether they are included in the water
quality standards.
§131.3
A-8
Appendix A. Acronyms, Abbreviations and Glossary
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NPDES Permit Writers' Manual
Term
Exhibit A-2 Glossary (continued)
Definition
Citation
Fact Sheet
Fundamentally
Different Factors
(FDF)
General Permit
Grab Sample
Hazardous
Substance
Indirect Discharger
Instantaneous
Maximum Limit
Instantaneous
Minimum Limit
Load Allocation
Local Limits
A document that must be prepared for all draft individual permits
for NPDES major dischargers, NPDES general permits, NPDES
permits that contain variances, NPDES permits that contain
sewage sludge land application plans and several other classes
of dischargers. The document summarizes the principal facts
and the significant factual, legal, methodological and policy
questions considered in preparing the draft permit and explains
how the public may comment (§§ 124.8 and 124.56). Where a
fact sheet is not required, a statement of basis must be
prepared (§ 124.7).
Those components of a petitioner's facility that are determined
to be so unlike those components considered by EPA during the
effluent guidelines and pretreatment standards rulemaking that
the facility is worthy of a variance from the effluent guidelines or
categorical pretreatment standards that would otherwise apply.
An NPDES permit issued under § 122.28 that authorizes a
category of discharges under the CWA within a geographical
area. A general permit is not specifically tailored for an
individual discharger.
A sample taken from a wastestream on a one-time basis without
consideration of the flow rate of the wastestream and without
consideration of time.
Any substance as designated under Part 116 pursuant to
CWA section 31 1 that presents an imminent and substantial
danger to the public health or welfare, including fish, shellfish,
wildlife, shorelines, and beaches, upon discharge to navigable
waters of the United States.
A nondomestic discharger introducing pollutants to a publicly
owned treatment works.
The maximum allowable concentration or other measure of a
pollutant determined from the analysis of any discrete or
composite sample collected, independent of the flow rate and
the duration of the sampling event.
The minimum allowable concentration or other measure of a
pollutant determined from the analysis of any discrete or
composite sample collected, independent of the flow rate and
the duration of the sampling event.
The portion of a receiving water's loading capacity that is
attributed either to one of its existing or future nonpoint sources
of pollution or to natural background sources. Load allocations
are best estimates of the loading, which may range from
reasonably accurate estimates to gross allotments, depending
on the availability of data and appropriate techniques for
predicting the loading. Wherever possible, natural and nonpoint
source loads should be distinguished.
Where specific prohibitions or limits on pollutants or pollutant
parameters are developed by a POTW in accordance with §
403. 4(c), such limits must be deemed Pretreatment Standards
for the purposes of CWA section 307(d).
1996PWM
Adapted from
1996PWM
1996PWM
Adapted from
1996PWM
Adapted from
§122.2 and
CWA section
311(b)(2)(A)
40CFR 122.2
1996PWM
-
§130.2
Adapted from
§ 403.4(d)
Appendix A. Acronyms, Abbreviations and Glossary
A-9
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NPDES Permit Writers' Manual
Term
Exhibit A-2 Glossary (continued)
Definition
Citation
Major Facility
Method Detection
Limit (MDL)
Maximum Daily
Effluent Limitation
(MDL)
Million Gallons per
Day (or mgd)
Minimum Level
(ML)
Mixing Zone
Municipal Separate
Storm Sewer
System (MS4)
Municipal Sludge
Any NPDES facility or activity classified as such by the Regional
Administrator, or in the case of approved state programs, the
Regional Administrator in conjunction with the State Director (§
122.2). Major municipal dischargers include all facilities with
design flows of greater than one million gallons per day and
facilities with EPA/state approved industrial pretreatment
programs. Major industrial facilities are determined based on
specific ratings criteria developed by EPA or are classified as
such by EPA in conjunction with the state.
The minimum concentration of a substance that can be
measured and reported with 99% confidence that the analyte
concentration is greater than zero and is determined from
analysis of a sample in a given matrix containing the analyte.
The highest allowable daily discharge of a pollutant. (Chapter 6)
A unit of flow commonly used for wastewater discharges. One
million gallon per day is equivalent to 1 .547 cubic feet per
second.
The level at which the entire analytical system must give a
recognizable signal and acceptable calibration point. It is
equivalent to the concentration of the lowest calibration
standard, assuming that all method-specified sample weights,
volumes, and cleanup procedures have been employed.
An area where an effluent discharge undergoes initial dilution
and is extended to cover the secondary mixing in the ambient
waterbody. A mixing zone is an allocated impact zone where
water quality criteria can be exceeded as long as acutely toxic
conditions are prevented.
A conveyance or system of conveyances (including roads with
drainage systems, municipal streets, catch basins, curbs,
gutters, ditches, man-made channels, or storm drains):
a. Owned or operated by a state, city, town, borough,
county, parish, district, association, or other public
body (created by or pursuant to state law) having
jurisdiction over disposal of sewage, industrial wastes,
stormwater, or other wastes, including special districts
under state law such as a sewer district, flood control
district or drainage district, or similar entity, or an
Indian tribe or an authorized Indian tribal organization,
or a designated and approved management agency
under CWA section 208 that discharges to waters of
the United States.
b. Designed or used for collecting or conveying
stormwater.
c. [That] is not a combined sewer.
d. [That] is not part of a Publicly Owned Treatment Works
(POTW) as defined at § 122.2.
See Sewage Sludge.
1996PWM
§ 136 -Appendix B
-
1996PWM
§ 136 -Appendix A
Technical Support
Document for Water
Quality-based Toxics
Control
§ 122.26(b)(8)
-
A-10
Appendix A. Acronyms, Abbreviations and Glossary
-------
September 2010
NPDES Permit Writers' Manual
Term
Exhibit A-2 Glossary (continued)
Definition
Citation
National Pollutant
Discharge
Elimination System
(NPDES)
The national program for issuing, modifying, revoking and
reissuing, terminating, monitoring and enforcing permits, and
imposing and enforcing pretreatment requirements, under CWA
sections 307, 318, 402, and 405. The term includes approved
program. NPDES permits regulate discharges of pollutants from
point sources to waters of the United States. Such discharges
are illegal unless authorized by an NPDES permit.
Adapted from
§ 122.2
National
Pretreatment
Standard or
Pretreatment
: Standard
Any regulation promulgated by EPA in accordance with CWA
sections 307(b) and 307(c) that applies to a specific category of
industrial users and provides limitations on the introduction of
pollutants into publicly owned treatment works. The term
includes the prohibited discharge standards under § 403.5.
Adapted from
§403.3(1)
New Discharger
Any building, structure, facility, or installation:
a. From which there is or may be a discharge of
pollutants.
b. That did not begin the discharge of pollutants at that
site before August 13, 1979.
c. That is not a new source.
d. That has never received a finally effective NPDES
permit for discharges at that site.
This definition includes an indirect discharger that begins
discharging into waters of the United States after August 13,
1979. It also includes any existing mobile point source (other
than an offshore or coastal oil and gas exploratory drilling rig or
a coastal oil and gas developmental drilling rig) such as a
seafood processing rig, seafood processing vessel, or
aggregate plant, that begins discharging at a site for which it
does not have a permit; and any offshore or coastal mobile oil
and gas exploratory drilling rig or coastal mobile oil and gas
developmental drilling rig that commences the discharge of
pollutants after August 13, 1979, at a site under EPA's
permitting jurisdiction for which it is not covered by an individual
or general permit and which is in an area determined by the
Regional Administrator in the issuance of a final permit to be an
area or biological concern. In determining whether an area is an
area of biological concern, the Regional Administrator must
consider the factors specified in §§ 125.122(a)(1) -
125.122(a)(10).
An offshore or coastal mobile exploratory drilling rig or coastal
mobile developmental drilling rig will be considered a new
discharger only for the duration of its discharge in an area of
biological concern.
Adapted from
§ 122.2
Appendix A. Acronyms, Abbreviations and Glossary
A-ll
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September 2010
NPDES Permit Writers' Manual
Term
Exhibit A-2 Glossary (continued)
Definition
Citation
New Source
Any building, structure, facility, or installation from which there is
or could be a discharge of pollutants, the construction of which
commenced:
a. After promulgation of standards of performance under
CWA section 306, which are applicable to such source;
or
b. After proposal of standards of performance in
accordance with CWA section 306, which are
applicable to such source but only if the standards are
promulgated in accordance with CWA section 306
within 120 days of their proposal.
Additional Criteria:
Except as otherwise provided in an applicable new source
performance standard, a source is a new source if it meets
the definition in § 122.2; and
i. It is constructed at a site at which no other source
is located; or
ii. It totally replaces the process or production
equipment that causes the discharge of pollutants
at an existing source; or
ill. Its processes are substantially independent of an
existing source at the same site. In determining
whether these processes are substantially
independent, the Director shall consider such
factors as the extent to which the new facility is
integrated with the existing plant; and the extent
to which the new facility is engaged in the same
general type of activity as the existing source.
Adapted from
§122.2 and
§122.29(b)(1)
New Source
Performance
Standards (NSPS)
Technology standards for facilities that qualify as new sources
under § 122.2 and § 122.29. Standards consider that the new
source facility has an opportunity to design operations to more
effectively control pollutant discharges.
1996PWM
Nonconventional
Pollutants
All pollutants that are not included in the list of conventional or
toxic pollutants in Part 401. Includes pollutants such as
chemical oxygen demand (COD), total organic carbon (TOC),
nitrogen, and phosphorus.
1996PWM
Nonpoint Source
Diffuse pollution sources (i.e., without a single point of origin or
not introduced into a receiving stream from a specific outlet).
The pollutants are generally carried off the land by stormwater.
Atmospheric deposition and hydromodification are also sources
of nonpoint source pollution.
North American
Industrial
Classification
System (NAICS)
The North American Industry Classification System (NAICS) is
the standard used by federal statistical agencies in classifying
business establishments for the purpose of collecting,
analyzing, and publishing statistical data related to the U.S.
business economy.
Retrieved from
Nutrients
Chemical elements and compounds found in the environment
that plants and animals need to grow and survive. Nutrients
include compounds of nitrogen (nitrate, nitrite, ammonia,
organic nitrogen) and phosphorus (orthophosphate and others),
both natural and man-made.
Permitting
Authority
The agency authorized to issue and enforce specific
requirements of the NPDES permit program. The permitting
authority may be EPA, or a state, territorial, or tribal agency that
has been authorized under CWA section 402(b) to administer
the NPDES program within its jurisdiction.
A-12
Appendix A. Acronyms, Abbreviations and Glossary
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NPDES Permit Writers' Manual
Term
Exhibit A-2 Glossary (continued)
Definition
Citation
PH
A measure of the hydrogen ion concentration of water or
wastewater; expressed as the negative log of the hydrogen ion
concentration in mg/L. A pH of 7 is neutral. A pH less than 7 is
acidic, and a pH greater than 7 is basic.
1996PWM
Point Source
Any discernible, confined, and discrete conveyance, including
any pipe, ditch, channel, tunnel, conduit, well, discrete fixture,
container, rolling stock, concentrated animal feeding operation,
landfill leachate collection system, vessel or other floating craft
from which pollutants are or may be discharged. The term does
not include return flows from irrigated agriculture or agricultural
stormwater runoff.
Adapted from
§ 122.2
Pollutant
Dredged spoil, solid waste, incinerator residue, filter backwash,
sewage, garbage, sewage sludge, munitions, chemical wastes,
biological materials, radioactive materials (except those
regulated under the Atomic Energy Act of 1954, as amended
[42 U.S.C. 2011 et seq.)], heat, wrecked or discarded
equipment, rock, sand, cellar dirt and industrial, municipal, and
agricultural waste discharged into water. It does not mean
a. Sewage from vessels.
b. Water, gas, or other material that is injected into a well
to facilitate production of oil or gas, or water derived in
association with oil and gas production and disposed of
in a well, if the well used either to facilitate production
or for disposal purposes is approved by authority of the
state in which the well is located, and if the state
determines that the injection or disposal will not result
in the degradation of ground or surface water
resources.
§ 122.2
Pollutant,
Conservative
Pollutants that do not readily degrade in the environment and
that are mitigated primarily by dilution after entering receiving
waters (e.g., metals, total suspended solids).
Adapted from
1996PWM
Pollutant, Non-
Conservative
Pollutants that are mitigated by natural biodegradation or other
environmental decay or removal processes in the receiving
water after mixing and dilution have occurred (e.g., biochemical
oxygen demand, pH, volatile organic compounds).
Adapted from
1996PWM
Pretreatment
The reduction of the amount of pollutants, the elimination of
pollutants, or the alteration of the nature of pollutant properties
in wastewater prior to or in lieu of discharging or otherwise
introducing such pollutants into a POTW.
§403.3(s)
Primary Industry
Category
Any industry category listed in the NRDC settlement agreement
(Natural Resources Defense Council et al. v. Train, 8 E.R.C.
2120 [D.D.C. 1976], modified 12 E.R.C. 1833 [D.D.C. 1979]);
also listed in Appendix A of Part 122.
§ 122.2
Primary Treatment
The practice of removing some portion of the suspended solids
and organic matter in wastewater through sedimentation.
Common usage of this term also includes preliminary treatment
to remove wastewater constituents that may cause maintenance
or operational problems in the system (i.e., grit removal,
screening for rags and debris, oil and grease removal, etc.).
1996PWM
Priority Pollutants
Those pollutants considered to be of principal importance for
control under the CWA based on the NRDC Consent Decree
(NRDC et al. v. Train, 8 E.R.C. 2120 [D.D.C. 1976], modified
12 E.R.C. 1833 [D.D.C. 1979]); a list of the pollutants is
provided as Appendix A to 40 CFR Part 423.
1996PWM
Appendix A. Acronyms, Abbreviations and Glossary
A-13
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September 2010
NPDES Permit Writers' Manual
Term
Exhibit A-2 Glossary (continued)
Definition
Citation
| Process
Wastewater
Production-Based
Standard
| Proposed Permit
| Publicly Owned
I Treatment Works
(POTW)
| Sanitary Sewer
| Sanitary Sewer
Overflows (SSO)
| Secondary Industry
| Category
E Secondary
Treatment
Section 304(a)
Criteria
Self-Monitoring
Any water [that], during manufacturing or processing, comes
into direct contact with, or results from the production or use of
any raw material, intermediate product, finished product,
by-product, or waste product.
A discharge standard expressed in terms of pollutant mass
allowed per unit of product manufactured or some other
measure of production.
A state NPDES permit prepared after the close of the public
comment period (and when applicable, any public hearing and
administrative appeals) [that] is sent to EPA for review before
final issuance by the state. A proposed permit is not a draft
permit.
A treatment works as defined by CWA section 212, which is
owned by a state or municipality [as defined by CWA section
502(4)]. This definition includes any devices and systems used
in the storage, treatment, recycling, and reclamation of
municipal sewage or industrial wastes of a liquid nature. It also
includes sewers, pipes, and other conveyances only if they
convey wastewater to a POTW. The term also means the
municipality as defined in CWA section 502(4), which has
jurisdiction over the indirect discharges to and the discharges
from such a treatment works.
A pipe or conduit (sewer) intended to carry wastewater or water-
borne wastes from homes, businesses, and industries to the
POTW.
Untreated or partially treated sewage overflows from a sanitary
sewer collection system.
Any industry category, which is not a primary industry category.
Technology-based requirements for direct discharging POTWs.
Standard is based on the expected performance of a
combination of physical and biological processes typical for the
treatment of pollutants in municipal sewage. Standards are
expressed as a minimum level of effluent quality in terms of:
BOD5, total suspended solids (TSS), and pH (except as
provided by treatment equivalent to secondary treatment and
other special considerations).
Developed by EPA under authority of CWA section 304(a)
based on the latest scientific information on the relationship that
the effect of a constituent concentration has on particular
aquatic species and/or human health. This information is issued
periodically to the states as guidance for use in developing
criteria.
Sampling and analyses performed by a facility to determine
compliance with effluent limitations or other regulatory
requirements.
§ 122.2
1996PWM
§ 122.2
§403.3(q)
1996PWM
1996PWM
§ 122.2
Adapted from
1996PWM
§131.3(c)
1996PWM
A-14
Appendix A. Acronyms, Abbreviations and Glossary
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September 2010
NPDES Permit Writers' Manual
Term
Exhibit A-2 Glossary (continued)
Definition
Citation
Sewage Sludge
Any solid, semi-solid, or liquid residue removed during the
treatment of municipal waste water or domestic sewage.
Sewage sludge includes solids removed during primary,
secondary, or advanced wastewater treatment, scum, septage,
portable toilet pumpings, type III marine sanitation device
pumpings (33 CFR Part 159), and sewage sludge products.
Sewage sludge does not include ash generated during the firing
of sewage sludge in a sewage sludge incinerator or grit and
screenings generated during preliminary treatment of domestic
sewage in a treatment works.
Adapted from § 122.2
and Part 503
Significant
Industrial User
(SIU)
An indirect discharger that is the focus of control efforts under
the National Pretreatment Program.
SILJs include [with exceptions provided under § 403.3(v)]:
i. All Industrial Users subject to Categorical Pretreatment
Standards under § 403.6 and Chapter 1, Subchapter
N.
ii. Any other Industrial User that: discharges an average
of 25,000 gallons per day or more of process
wastewater to the POTW (excluding sanitary,
noncontact cooling and boiler blowdown wastewater);
contributes a process wastestream that makes up 5
percent or more of the average dry weather hydraulic
or organic capacity of the POTW; or is designated as
such by the Control Authority on the basis that the
Industrial User has a reasonable potential for adversely
affecting the POTW's operation or for violating any
Pretreatment Standard or requirement [in accordance
with § 403.8(f)(6)].
Adapted from
§403.3(v)
Spill Prevention
Control and
Countermeasure
Plan (SPCC)
A plan prepared by a facility to minimize the likelihood of a spill
and to expedite control and cleanup activities if a spill occurs.
Such plans are required for certain facilities under the Oil
Pollution Prevention Regulations at 40 CFR Part 112.
Adapted from
1996PWM
Standard Industrial
Classification (SIC)
Code
A code number system used to identify various types of
industries. A particular industry may have more than one SIC
code if it conducts several types of commercial or manufacturing
activities onsite. An online version of the 1987 SIC Manual
is available Courtesy Of the
Occupational Safety & Health Administration (OSHA).
Adapted from
1996PWM
Statement of Basis
A document prepared for every draft NPDES permit for which a
fact sheet is not required. A statement of basis briefly describes
how permit conditions were derived and the reasons the
conditions are necessary for the permit.
1996PWM
STORET
EPA's computerized STOrage and RETrieval water quality data
base that includes physical, chemical, and biological data
measured in waterbodies throughout the United States.
1996PWM
Storm Water (or
Stormwater)
Stormwater runoff, snow melt runoff, and surface runoff and
drainage.
§122.26(b)(13)
Tech nology-Based
Effluent Limitation
(TBEL)
An effluent limit for a pollutant that is based on the capability of
a treatment method to reduce the pollutant to a certain
concentration or mass loading level. TBELs for POTWs are
derived from the secondary treatment regulations in Part 133 or
state treatment standards. TBELs for non-POTWs are derived
from effluent guidelines, state treatment standards, or by the
permit writer on a case-by-case basis using best professional
judgment.
Adapted from
1996PWM
Appendix A. Acronyms, Abbreviations and Glossary
A-15
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September 2010
NPDES Permit Writers' Manual
Term
Exhibit A-2 Glossary (continued)
Definition
Citation
Tiered Permit
Limits
Permit limits that apply to the discharge only when a certain
threshold (e.g., production level), specific circumstance (e.g.,
batch discharge), or time frame (e.g., after 6 months, during the
months of May through October) triggers their use.
Adapted from
1996PWM
Total Maximum
Daily Load (TMDL)
The sum of the individual wasteload allocations (WLAs) for point
sources and load allocations (LAs) for nonpoint sources and
natural background. If a receiving water has only one point
source discharger, the TMDL is the sum of that point source
WLA plus the LAs for any nonpoint sources of pollution and
natural background sources, tributaries, or adjacent segments.
TMDLs can be expressed in terms of either mass per time,
toxicity, or other appropriate measure. If best management
practices (BMPs) or other nonpoint source pollution controls
make more stringent load allocations practicable, then
wasteload allocations can be made less stringent. Thus, the
TMDL process provides for nonpoint source control tradeoffs.
40CFR§130.2(i)
Total Suspended
Solids (TSS)
A measure of the filterable solids present in a sample, as
determined by the method specified in Part 136.
1996PWM
Toxic Pollutant
Any pollutant listed as toxic under CWA section 307(a)(1) or, in
the case of sludge use or disposal practices, any pollutant
identified in regulations implementing CWA section 405(d).
§ 122.2
Toxicity Reduction
Evaluation (TRE)
A site-specific study conducted in a step-wise process designed
to identify the causative agent(s) of effluent toxicity, isolate the
sources of toxicity, evaluate the effectiveness of toxicity control
options, and then confirm the reduction in effluent toxicity.
1996PWM
Toxicity Test
A procedure to determine the toxicity of a chemical or an
effluent using living organisms. A toxicity test measures the
degree of effect on exposed test organisms of a specific
chemical or effluent.
1996PWM
Trading (or Water
Quality Trading)
An innovative approach to achieve water quality goals more
efficiently. Trading is based on the fact that sources in a
watershed can face very different costs to control the same
pollutant. Trading programs allow facilities facing higher
pollution control costs to meet their regulatory obligations by
purchasing environmentally equivalent (or superior) pollution
reductions from another source at lower cost, thus achieving the
same water quality improvement at lower overall cost.
Water Quality Trading
Fact Sheet:
Treatability Manual
Five-set library of EPA guidance manuals that contain
information related to the treatability of many pollutants. The
manual may be used in developing effluent limitations for
facilities and pollutants, which, at the time of permit issuance,
are not subject to industry-specific effluent guidelines. The five
volumes that comprise this series consist of Vol. I - Treatability
Data (EPA-600/8-80-042a); Vol. II - Industrial Descriptions
(EPA-600/8-80-042b); Vol. Ill -Technologies (EPA-600/8-80-
042c); Vol. IV- Cost Estimating (EPA-600/8-80-042d); and
Vol. V - Summary (EPA-600/8-80-042e).
1996PWM
Treatment Works
Treating Domestic
Sewage (TWTDS)
A POTW or any other sewage sludge or waste water treatment
devices or systems, regardless of ownership (including federal
facilities), used in the storage, treatment, recycling, and
reclamation of municipal or domestic sewage, including land
dedicated for the disposal of sewage sludge. This definition
does not include septic tanks or similar devices. For purposes of
this definition, domestic sewage includes waste and waste
water from humans or household operations that are discharged
to or otherwise enter a treatment works.
Adapted from
§ 122.2
A-16
Appendix A. Acronyms, Abbreviations and Glossary
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September 2010
NPDES Permit Writers' Manual
Term
Exhibit A-2 Glossary (continued)
Definition
Citation
Upset
An exceptional incident in which there is unintentional and
temporary noncompliance with technology-based permit effluent
limitations because of factors beyond the reasonable control of
the permittee. An upset does not include noncompliance to the
extent caused by operational error, improperly designed
treatment facilities, inadequate treatment facilities, lack of
preventive maintenance, or careless or improper operation.
§122.41(n)
Use Attainability
Analysis
A structured scientific assessment of the factors affecting the
attainment of the use that [can] include physical, chemical,
biological, and economic factors as described in § 131.10(g).
§131.3
Variance
Any mechanism or provision under CWA sections 301 or 316 or
under 40 CFR Part 125, or in the applicable effluent limitations
guidelines, which allows modification to or waiver of the
generally applicable effluent limitation requirements or time
deadlines of the CWA. This includes provisions, [that] allow the
establishment of alternative limitations based on fundamentally
different factors or on CWA sections 301 (c), 301 (g), 301 (h),
or316(a).
§ 122.2
Wasteload
I Allocation (WLA)
The portion of a receiving water's loading capacity that is
allocated to one of its existing or future point sources of
pollution.
Adapted from
§130.2(h)
Water Quality
Criteria
Elements of state water quality standards, expressed as
constituent concentrations, levels, or narrative statements,
representing a quality of water that supports a particular use.
When criteria are met, water quality will generally protect the
designated use.
§131.3(b)
> Water Quality
Limited Segment
Any segment where it is known that water quality does not meet
applicable water quality standards, and/or is not expected to
meet applicable water quality standards, even after the
application of the technology-based effluent limitations required
by CWA sections 301 (b) and 306.
§131.3
Water Quality
Standards (WQS)
Provisions of state or federal law that consist of a designated
use or uses for the waters of the United States and water quality
criteria for such waters based on such uses. Water quality
standards are to protect the public health or welfare, enhance
the quality of water, and serve the purposes of the CWA.
Adapted from
§131.3
I Water Quality-
Based Effluent
Limitation (WQBEL)
An effluent limitation determined by selecting the most stringent
of the effluent limits calculated using all applicable water quality
criteria (e.g., aquatic life, human health, wildlife, translation of
narrative criteria) for a specific point source to a specific
receiving water.
Adapted from
1996PWM
Appendix A. Acronyms, Abbreviations and Glossary
A-17
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September 2010
NPDES Permit Writers' Manual
Term
Exhibit A-2 Glossary (continued)
Definition
Citation
Waters of the
United States
Means
a. All waters [that] are currently used, were used in the
past, or [could] be susceptible to use in interstate or
foreign commerce, including all waters [that] are
subject to the ebb and flow of the tide.
b. All interstate waters, including interstate wetlands.
c. All other waters such as intrastate lakes, rivers,
streams (including intermittent streams), mudflats,
sandflats, wetlands, sloughs, prairie potholes, wet
meadows, playa lakes, or natural ponds the use,
degradation, or destruction of which would affect or
could affect interstate or foreign commerce including
any such waters
1. [That] are or could be used by interstate or foreign
travelers for recreational or other purposes.
2. From which fish or shellfish are or could be taken
and sold in interstate or foreign commerce or
3. [That] are used or could be used for industrial
purposes by industries in interstate commerce.
d. All impoundments of waters otherwise defined as
waters of the United States under this definition.
e. Tributaries of waters identified in paragraphs (a)
through (d) of this definition.
f. The territorial sea and
g. Wetlands adjacent to waters (other than waters that
are themselves wetlands) identified in paragraphs (a)
through (f) of this definition.
[see additional notes in § 122.2]
§ 122.2
Whole Effluent
Toxicity (WET)
The aggregate toxic effect of an effluent measured directly by a
toxicity test.
§ 122.2
A-18
Appendix A. Acronyms, Abbreviations and Glossary
-------
September 2010
NPDES Permit Writers' Manual
Appendix B. Index to the CWA and NPDES Regulations
This appendix provides two tables to help permit writers navigate Clean Water Act (CWA) legislation
and National Pollutant Discharge Elimination System (NPDES) regulations. The first table provides key
sections of the CWA and the second table provides an index to NPDES regulations.
B.1 Index to Sections of the CWA
Title 33 of the United States Code (U.S.C.) includes the statutes and amendments to the CWA. Exhibit
B-l matches key sections of the CWA to the appropriate reference in the U.S.C. This latest version, dated
December 20, 2004, was provided by the New England Interstate Water Pollution Control Commission.
Exhibit B-1 Index to sections of the CWA
33 U.S.C. section
Section title
CWA section
\ Subchapter I Research and Related Programs
j 1251
\ 1252
! 1253
\ 1254
\ 1255
\ 1256
\ 1257
| 1258
j 1259
j 1260
\ 1261
\ 1262
\ 1263
\ 1265
i 1266
\ 1267
\ 1268
\ 1269
\ 1270
i 1273
| 1274
Congressional declaration of goals and policy
Comprehensive programs for water pollution control
Interstate cooperation and uniform laws
Research, investigations, training and information
Grants for research and development
Grants for pollution control programs
Mine water pollution demonstrations
Pollution control in the Great Lakes
Training grants and contracts
Applications for training grants and contracts; allocations
Scholarships
Definitions and authorization
Alaska village demonstration project
In-place toxic pollutants
Hudson River reclamation demonstration project
Chesapeake Bay
Great Lakes
Long Island Sound
Lake Champlain management conference
Lake Pontchartrain Basin
Wet weather watershed pilot projects
101 |
102
103
104
105 |
106
107
108
109 |
110
111
112
113 |
115
116
117
118
119 |
120
121
121
Subchapter II Grants for Construction of Treatment Works
\ 1281
! 1282
\ 1283
\ 1284
\ 1285
\ 1286
| 1287
\ 1288
\ 1289
Congressional declaration of purpose
Federal share
Plans, specifications, estimates, and payments
Limitations and conditions
Allotment of grant funds
Reimbursement and advanced construction
Authorization of appropriations
Area wide waste treatment management
Basin planning
201
202
203
204 |
205
206
207
208 |
209
Appendix B. Index to the CWA and NPDES Regulations
B-l
-------
September 2010
NPDES Permit Writers' Manual
Exhibit B-1 Index to sections of the CWA (continued)
Section title
33 U.S.C. section
CWA section
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
Annual survey
Sewage collection system
Definitions
Loan guarantees
Wastewater recycling and reuse information and education
Requirements for American materials
Determination of priority
Guidelines for cost-effective analysis
Cost effectiveness
State certification of projects
Pilot program for alternative water source projects
Sewer overflow control grants
210 I
211 |
212
213
214 j
215 j
216
217
218 j
219 |
220
221
Subchapter III Standards and Enforcement
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1328
1329
1330
Effluent Limitations
Water quality-related effluent limitations
Water quality standards and implementation plans
Information and guidelines
Water quality inventory
National standards of performance
Toxic and pretreatment effluent standards
Records and reports, inspections
Enforcement
International pollution abatement
Oil and hazardous substance liability
Marine sanitation devices
Federal facility pollution control
Clean lakes
National study commission
Thermal discharges
Aquaculture
Nonpoint source management program
National estuary study
301 I
302
303
304 j
305 |
306
307
308 j
309 |
310
311
312 j
313 |
314
315
316
318 j
319 |
320
Subchapter IV Permits and Licenses
1341
1342
1343
1344
1345
1346
Certification
National pollutant discharge elimination system
Ocean discharge criteria
Permits for dredge and fill materials
Disposal or use of sewage sludge
Coastal recreation water quality monitoring and notification
401 |
402 j
403
404
405 j
406 |
Subchapter V General Provisions
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
Administration
Definitions
Water pollution control advisory board
Emergency powers
Citizen suits
Appearance
Employee protection
Federal procurement
Administrative procedure and judicial review
State authority
501
502 j
503 |
504
505
506 j
507 |
508
509
510 j
B-2
Appendix B. Index to the CWA and NPDES Regulations
-------
September 2010
NPDES Permit Writers' Manual
33 U.S.C. section
Exhibit B-1 Index to sections of the CWA (continued)
Section title
CWA section
1371
1251 Note
1372
1373
1374
1375
1376
1377
1251 Note
Authority under other laws and regulations
Separability
Labor standards
Public health agency coordination
Effluent standards and water quality information advisory committee
Reports to Congress
Authorization of appropriations
Indian tribes
Short Title
511
512
513
514
515
516
517
518
519
Subchapter VI State Water Pollution Control Revolving Funds
1381
1382
1383
1384
1385
1386
1387
Grants to States for establishment of revolving funds
Capitalization grant agreements
Water pollution control revolving loan funds
Allotment of funds
Corrective actions
Audits, reports, fiscal controls, intended use plan
Authorization of appropriations
601
602
603
604
605
606
607
B.2 to
The index to NPDES regulations table presented in Exhibit B-2 was created by Sylvia Kawabata of EPA
Region 10 on February 1, 1986, and is maintained by Doug Corb of EPA Region 1.
Exhibit B-2 Index to NPDES regulations
Subject
40 CFR section number
Selected CWA sections
CWA section 301 (c) - Modification of Timetable
CWA section 301 (g)
Pollutants
CWA section 301 (h)
CWA section 301 (n)
CWA section 31 6(a)
- Modifications for Certain Nonconventional
- Secondary Treatment Waiver
- Timetable for Achievement of Objectives
-Thermal Discharges
§ 122.21(m)(2) |
Part 125, Subpart F (reserved) |
Technical Guidance Manual for the
Regulations Promulgated Pursuant to section I
301 (g) of the Clean Water Act of 1 977 and 40 I
CFR Part 125 (Subpart F); August 22, 1984.
I
§122.21(n)(1) 5
Part 125, Subpart G ;i
See Fundamentally Different Factors I
§ 122.21(m)(6) I
Part 125, Subpart H I
§ 124.57 I
§ 124.62(a)(2) I
§ 124.66 I
§ 122.21(m)(2)
NPDES permit subjects
Administrative Procedures Act Permit Continuance
§ 122.6
Administrative Record
§ 124.9
§124.18
Appendix B. Index to the CWA and NPDES Regulations
B-3
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NPDES Permit Writers' Manual
Subject
Exhibit B-2 Index to NPDES regulations (continued)
40 CFR section number
Alternate Test Procedures
Application
Approval
Ambient Monitoring (for Indicator Parameters)
Anti-backsliding
Antidegradation Policy
Applicability to State NPDES Programs
Application
Submittal Deadline (Time to Apply)
Permit May Not Be Issued Without Complete Application
Completeness
Aquaculture
Aquatic Animal Production Facilities
Application
Definition
Criteria for Determination
General Permit
Average Monthly (Definition)
Requirements for use in Non-POTWs
Requirements for use in POTWs
Average Weekly (Definition)
Requirements for use in POTWs
Biochemical Oxygen Demand (BOD5)
Backsliding
From Water Quality and Technology Based Limits
From Water Quality
Best Management Practices
Definition
In Effluent Limitation Guidelines
Case-by-Case Authority
Best Professional Judgment (BPJ)
Case-by-Case Authority
Appropriate Factors
BMP
Boilerplate Permit Conditions
BPJ
Bypasses
CAFO
Calculating NPDES Permit Conditions
Carbonaceous Biochemical Oxygen Demand (CBODs)
Case-by-Case Limitations
Case-by-Case Permits
§136.4
§136.5
§122.44(d)(1)(vi)(C)(3)
See Backslidinq
§ 131.12
See General Conditions for All Permits (State
Proqrams)
§ 122.21
. §122.21(c)
. §122.21(e)
. §§ 124.3(c) -124.3(g)
§ 122.25
Part 125, Subpart B
§ 122.24
§122.21(i)(2)
§ 122.24
Part 122, Appendix C
§ 122.28
§ 122.2
. §122.45(d)(1)
. § 122.45(d)(2)
§ 122.2
. § 122.45(d)(2)
§ 133.101(d)
§ 122.44(1)
§122.62(a)(15)
§122.62(a)(17)
CWA section 402(o)
CWA section 303(d)(4)
§ 122.2
§ 122.44(k)
§130.2(m)
CWA section 304(e)
CWA section 402(a)(1)
. §125.3(a)(1)
§§125.3(c)and 125.3(d)
See Best Manaqement Practices
§§ 122.41 -122.42
See Best Professional Judqment
§ 122.41(m)
See Concentrated Animal Feedinq Operations
§ 122.45
§ 133.101(e)
See also BPJ
§ 122.44(a)
§125.3
See also BPJ
§ 124.52
B-4
Appendix B. Index to the CWA and NPDES Regulations
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September 2010
NPDES Permit Writers' Manual
Subject
Exhibit B-2 Index to NPDES regulations (continued)
40 CFR section number
Clean Water Act (CWA)
Coast Guard (Discharges from Transportation Over Water)
Coastal Zone Management Act
Combined Sewer Overflow Policy
Comments Received During Public Notice Period
Compliance Schedules (in permits)
Allowance by State Water Quality Standards
Computation of Time
Concentrated Animal Feeding Operations
Concentrated Aquatic Animal Production
Conditions Applicable to Specified Categories
Confidentiality of Information
Consolidation of Permit Processing
Continuation of Expired Permits
Continuous Discharge
Conventional Pollutants
Cooling Water Intake Structures [CWA section 316(b)]
DMR
Daily Average
Daily Maximum
Definitions
Denial of Permit
Public Notice of Denial
Design Flow (POTWs)
Dilution, Not A Substitute For Treatment
Discharge Monitoring Report (DMR)
Discharge of a Pollutant (Definition)
Disposal into Wells, into POTWs, or by Land Application
Draft Permit
Dredged Materials (Discharge to Waters of the United States)
Duration of Permits
Computation of time
Duty to Comply
Duty to Mitigate
Duty to Provide Information
Duty to Reapply
Effect of a Permit
(Public Law 92-500), 33 U.S.C. 1251 et seq.,
as amended by Public Laws 96-483; 97-117;
95-217, 97-117, 97-440, and 100-04
§ 122.44(p)
§ 122.49(d)
59 FR 18688, April 19, 1994
§124.13
§122.41(l)(5)
§ 122.47
§§ 122.62(a)(4), (a)(9), (a)(13)
Star-kist Caribe, Inc., NPDES Appeal No.
88-5
(EAB,
May 25, 1992)
§ 124.20
§ 122.23
See Aquatic Animal Production
§ 122.42
§ 122.7
Part 2
§ 124.4
§ 122.6
§ 122.45(d)
§401.16
Part 125, Subparts I, J and N
§122.21(r)
§401.14
See Discharge Monitoring Report
See Average Monthly
See Maximum Daily
§ 122.2
§ 124.2
§401.11
§ 124.6(b)
. §124.10(a)(1)(i)
§122.45(b)(1)
§122.45(f)(1)(iii)
§ 125.3(f)
§ 122.41(l)(4)
§ 122.2
§ 122.50
§ 122.45(i)
§ 124.6
CWA section 404
§ 122.46
§ 124.20
§122.41(a)
§122.41(d)
§122.41(h)
§122.41(b)
§ 122.5
Appendix B. Index to the CWA and NPDES Regulations
B-5
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September 2010
NPDES Permit Writers' Manual
Subject
Exhibit B-2 Index to NPDES regulations (continued)
40 CFR section number
Effective Date
Effluent Limitations Guidelines (Effluent Guidelines or ELG)
Endangered Species Act
Enforcement Authority
Environmental Impact Statement (EIS)
EIS Public Notice of a New Source
Final EIS
New Source
NEPA
Equivalent To Secondary Treatment (for POTWs)
Establishing Limitations, Standards
Establishing Permit Conditions
Evidentiary Hearing Procedures (Eliminated)
Exclusions
Existing Source (Definition)
Expiration Dates
Extension of Public Notice Comment Period
PDF
Fact Sheets
Feedlots
Filter Backwash
Fish and Wildlife Coordination Act
Fish Farms
Flow Augmentation
Flow Limits (POTW- Design Flow)
Flow Monitoring Requirement
Fundamentally Different Factors (FDF)
Frequency of Sampling (Not less than once per year)
General Conditions Applicable to All Permits
General Conditions for All Permits (State Programs)
General Permits
Public Notice
Individual Permit Required
Great Lakes Water Quality Guidance
Indian Tribe (Definition)
Innovative Technology
Inspection and Entry
Internal Waste Streams
Interim Dates for Schedules of Compliance
Introduction of New Pollutants (POTW)
Issuance and Effective Date
Mass Limitations
Maximum Daily (Definition)
Requirements for Non-POTWs
Metals (To Be Expressed as Total Recoverable)
§ 124.15
Parts 405-471
§ 122.49(c)
§ 123.27
§124.10(b)(1)
§ 124.61
§ 122.29(c)
Part 6
§ 133.105
§ 122.44
§ 122.43
§§124.21 (b)-(c)
§ 122.3
§ 122.29(a)(3)
See Duration of Permits
§124.12(c)
See Fundamentally Different Factors
§ 124.8
§ 124.56
See Concentrated Animal Feedinq Operations
§ 125.3(g)
§ 122.49(e)
See Aquatic Animal Production Facilities
§ 125.3(f)
§ 122.45(b)
§ 122.44(i)(1 )(ii)
§122.21(m)(1)
§ 122.44(d)(8)
Part 125, Subpart D
§ 122.44(i)(2)
§ 122.41
§ 123.25
§ 122.28
. §124.10(c)(2)(i)
§ 122.28(b)(3)
Part 132
§ 124.2
See CWA section 301 (k) - Innovative
Technology
§122.41(1)
§ 122.45(h)
§ 122.47(a)(3)
§ 122.42(b)
§124.15
§ 124.60
§ 122.45(f)
§122.44(i)(1)(i)
§ 122.2
. §122.45(d)(1)
§ 122.45(c)
B-6
Appendix B. Index to the CWA and NPDES Regulations
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September 2010
NPDES Permit Writers' Manual
Subject
Exhibit B-2 Index to NPDES regulations (continued)
40 CFR section number
Method Detection Limit
Minor Modifications
Mixing Zones
Modifications
Monitoring Results, Requirements for Recording and Reporting
Monitoring and Records
Monitoring Reports
Requirements
Recordkeeping
Municipal Separate Storm Sewer Systems (MS4)
When Permit Required
Definitions
Large and Medium MS4s Application Requirements
Small MS4 Requirements
Tribes
NPDES (Definition)
National Environmental Policy Act (NEPA)
National Historic Preservation Act
Navigable Waters (Definition)
Navigation
Need to Halt or Reduce Activity, Not a Defense
Net/Gross - Intake Credits
New Discharger (Definition)
New Source
Definition
Application Requirements
Program Requirements
Determination
Mitigation Measures
Prohibited discharges
Public Notice
Non-Attainment Waters
Non-Continuous Discharges
Noncompliance
Anticipated
Other
Notification Levels
General
For Existing Manufacturing, Commercial, Mining, and
Silvicultural Dischargers
Ocean Discharge Criteria
Offshore Oil and Gas Facilities
Requirements Applicable to Cooling Water Intake Structures
for New Offshore Oil and Gas Extraction Facilities under CWA
section 316(b)
General Permit Requirements & Application
Effluent Guidelines and Standards
Stormwater Exemption
Oil Pollution Prevention
Part 136, Appendix B
§ 122.63
§ 131.13
§ 122.62
§ 124.5
§ 122.48
§ 122.410)
§122.41(l)(4)
§ 122.44(h)
§122.21(p)
§§ 122.26(a)(3), (4), and (5)
§ 122.26(b)
§ 122.26(d)
§§ 122.30 and 122.32-122.37
§122.31
§ 122.2
§ 122.49(g)
§ 122.49(b)
§110.1
§ 122.44(q)
§122.41(c)
§ 122.45(g)
§ 122.2
§ 122.2
§122.21(k)
§ 122.29
§ 122.29(b)
§ 122.44(d)(9)
§122.4(i)
. §124.10(a)(1)(vi)
§ 130.10(d)
§ 122.45(e)
§122.41(l)(2)
§122.41(0(7)
§ 122.62(a)(12)
§122.42(a)
§ 122.44(f)
Part 125, Subpart M
Part 125, Subpart N
§ 122.28(c)
Part 435, Subpart A
§ 122.26(a)(2)
Part 112
Appendix B. Index to the CWA and NPDES Regulations
B-7
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September 2010
NPDES Permit Writers' Manual
Subject
Exhibit B-2 Index to NPDES regulations (continued)
40 CFR section number
On-Site Construction (New Source)
| Operation and Maintenance
pH Limits with Continuous Monitoring
| Planned Changes
j Pollutant (Definition)
| POTWs, Applications for New and Existing
Pretreatment
| Primary Industry Categories
j Prior Notice of Citizen Suits (Under CWA)
Priority Pollutants
Privately Owned Treatment Works
| Production-based Limitations
Prohibitions
| Proper Operation and Maintenance
Property Rights
| Public Hearing
Public Notice for Public Hearings
| Public Notice
Specific Procedures Applicable to NPDES Permits
| Reapplication
| Recordkeeping and Reporting
| Reopener Clause
| Treatment Works Treating Domestic Sewage
Other
| Reopening of Public Comment Period
| Response to Comments
Reasonable Potential (RP)- Need For A Limit
| Chemical Specific
Whole Effluent Toxicity (WET)
I Retention of Records
I Revocation and Reissuance
I Sample Type (Composite/Grab)
| Sample Holding Times, Containers, and Preservation
Sample, Representative
Schedule of Compliance (Definition)
| Secondary Treatment Regulation (POTW)
Definitions
Secondary Treatment
| Special Considerations
| Treatment Equivalent to Secondary Treatment
Signatory Requirements
| Silviculture
§ 122.29(b)(4)
§122.41(e)
§401.17
§122.41(l)(1)
§ 122.2
§122.210
§ 122.440)
Part 403
Part 122, Appendix A
Part 135
Part 423, Appendix A
§ 122.44(m)
§ 122.45(b)
§ 122.4
§122.41(e)
§122.41(g)
§124.12
. §124.10(b)(2)
§124.10(d)(2)
§124.10
§124.57
§ 122.21(d)
§122.21(p)
§ 122.410X2)
§ 122.48
§ 122.44(c)
. § 122.62(a)(7)
§124.14
§124.17
§122.44(d)(1)
. §122.44(d)(1)(vi)
. §122.44(d)(1)(v)
§122.410(2)
§ 122.62
§ 122.21(g)(7)(i)
§ 136.3
§ 122.410)
See also Compliance Schedule
§ 124.2
Part 133
§133.101
§133.102
§133.103
§133.105
§ 122.22
§ 122.27
B-8
Appendix B. Index to the CWA and NPDES Regulations
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September 2010
NPDES Permit Writers' Manual
Subject
Exhibit B-2 Index to NPDES regulations (continued)
40 CFR section number
Sludge (Definition)
Sludge Standards
| Land Application
| Surface Disposal
Pathogens and Vector Attraction Reduction
I Incineration
| Sludge, Municipal Co-Disposal Landfills
Sludge-Only Facilities (Handlers)
| Small Business Exemption
Solid Waste Facilities, Classification of
| Spill Prevention, Control, and Countermeasures (SPCC)
Standard Conditions
| State Certification
| Applications for CWA section 301 (h) Variances
I Effect of State Certification
| State Program Requirements
Statutory Deadlines
ForPOTWs
ForNon-POTWs
Statutory Variances and Extensions
| Stays of Contested Permit Conditions
Stormwater
Discharge Associated with Industrial Activity
Test Methods, EPA Approved
| Ten-Year Protection Period
Termination of a Permit
Thermal Discharge Variance
| Total Maximum Daily Load (TMDL)
| Definition
Which Waterbodies Need TMDLs
Toxics- Application and Testing
Toxic Pollutants (Definition)
Technology-based Controls
I Toxic Pollutant List
Toxicity Based Permit Limits
| Transfer of Permit
Treatment Works Treating Domestic Sewage Sludge (TWTDS)
(Definition)
Twenty-four Hour Reporting
| Upset
Variances for
Non-POTWs
POTWs
| Appeals of variances
Decisions on variances
Expedited variance procedures and time extensions
[ Procedures for variances when EPA is the permitting authority
§ 122.44(0)
Part 503
Part 503, Subpart B
Part 503, Subpart C
Part 503, Subpart D
Part 503, Subpart E
Part 258
§122.1(b)(3)
§122.21(g)(8)
Part 257
§ 112.3
§§ 122.41 and 122.42
§ 124.53
§ 124.54
§ 124.55
Part 123
. §125.3(a)(1)
. §125.3(a)(2)
§ 125.3(b)
§ 124.16
§ 122.26
§ 122.26(b)(14)
Part 136
See also New Sources and Dischargers
§ 122.29
§ 122.64
See CWA section 316(a) - Thermal
Discharges
§130.2
§130.7
§122.21(g)(7)
§122.21(g)(9)
§122.21(g)(11)
§ 122.2
§ 122.44(e)
§401.15
§ 125.3(c)(4)
§122.61
§ 122.2
§ 122.41(l)(6)
§122.41(n)
§122.21(m)
. §122.21(n)
§ 124.64
§ 124.62
§122.21(0)
§ 124.63
Appendix B. Index to the CWA and NPDES Regulations
B-9
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NPDES Permit Writers' Manual
Exhibit B-2 Index to NPDES regulations (continued)
Subject 40 CFR section number
Vessel (Definition)
Waste Stabilization Ponds (POTW)
Water Quality Report - CWA section 305(b)
Water Quality Standards (WQS)
Scope
Purpose
Definitions
State Authority
EPA Authority
Submission, Minimum Requirements
Dispute Resolution
Establishment of Standards
Criteria
Antidegradation Policy
General Policies on Establishing WQS
State Review and Revision of WQS
EPA Review and Approval of WQS
EPA Promulgation of WQS
Federally Promulgated Standards (State-By-State List)
Waters of the United States (Definition)
Wetlands
Whole Effluent Toxicity (WET) Limits
WET Testing With Permit Application (POTWs)
Wild and Scenic Rivers Act
Withdrawal Of State Program
§112.2
§133.103(c)
§130.8
Part 131
§131.1
§131.2
§131.3
§131.4
§131.5
§131.6
§131.7
§131.10
§131.11
§131.12
§131.13
§131.20
§131.21
§131.22
Part 131, Subpart D
§ 122.2
See Waters of the U.S.
§ 122.2
§122.44(d)(1)(iv)
§ 125.3(c)(4)
§122.210
§ 122.49(a) |
§§ 123.63-123.64
B-10
Appendix B. Index to the CWA and NPDES Regulations
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NPDES Permit Writers' Manual
Appendix C. Priority Pollutants
Exhibit C-l presents the list of 126 priority (toxic) pollutants from 40 CFR Part 423 Appendix A, which
are further discussed in sections 1.2 and 6.1.1.2 of this manual. Note that the list goes up to 129 because
numbers 017, 049, and 050 were deleted.
Exhibit C-1 Priority pollutants from 40 CFR Part 423, Appendix A
#
I 001
j 002
j 003
| 004
005
006
I 007
j 008
| 009
010
011
I 012
j 013
j 014
I °15
016
018
I 019
j 020
j 021
| 022
023
024
I 025
j 026
I °27
| 028
029
030
I 031
j 032
| 033
I °34
035
I 036
I °37
j 038
| 039
040
Pollutant name
Acenaphthene
Acrolein
Acrylonitrile
Benzene
Benzidine
Carbon tetrachloride (tetrachloromethane)
Chlorobenzene
1 ,2,4-trichlorobenzene
Hexachlorobenzene
1,2-dichloroethane
1,1,1-trichloreothane
Hexachloroethane
1,1-dichloroethane
1,1,2-trichloroethane
1 , 1 ,2,2-tetrachloroethane
Chloroethane
Bis(2-chloroethyl) ether
2-chloroethyl vinyl ether (mixed)
2-chloronaphthalene
2,4, 6-trichlorophenol
Parachlorometa cresol
Chloroform (trichloromethane)
2-chlorophenol
1,2-dichlorobenzene
1 ,3-dichlorobenzene
1,4-dichlorobenzene
3,3-dichlorobenzidine
1,1-dichloroethylene
1 ,2-trans-dichloroethylene
2,4-dichlorophenol
1,2-dichloropropane
1 ,2-dichloropropylene (1 ,3-dichloropropene)
2,4-dimethylphenol
2,4-dinitrotoluene
2,6-dinitrotoluene
1 ,2-diphenylhydrazine
Ethylbenzene
Fluoranthene
4-chlorophenyl phenyl ether
#
067
068
069
070
071
072
073
074
075
076
077
078
079
080
081
082
083
084
085
086
087
088
089
090
091
092
093
094
095
096
097
098
099
100
101
102
103
104
105
Pollutant name E
Butyl benzyl phthalate
Di-N-Butyl Phthalate
Di-n-octyl phthalate
Diethyl Phthalate
Dimethyl phthalate
1,2-benzanthracene (benzo(a) anthracene
Benzo(a)pyrene (3,4-benzo-pyrene)
3,4-Benzofluoranthene (benzo(b) fluoranthene)
11,12-benzofluoranthene (benzo(b) fluoranthene)
Chrysene
Acenaphthylene
Anthracene
1,12-benzoperylene (benzo(ghi) perylene)
Fluorene
Phenanthrene
1,2,5,6-dibenzanthracene (dibenzo(.h) anthracene)
Indeno (,1,2,3-cd) pyrene (2,3-o-pheynylene pyrene)
Pyrene
Tetrachloroethylene
Toluene
Trichloroethylene
Vinyl chloride (chloroethylene)
Aldrin
Dieldrin
Chlordane (technical mixture and metabolites)
4,4-DDT
4,4-DDE (p,p-DDX)
4,4-DDD (p,p-TDE)
Alpha-endosulfan
Beta-endosulfan
Endosulfan sulfate
Endrin
Endrin aldehyde
Heptachlor
Heptachlor epoxide (BHC-hexachlorocyclohexane)
Alpha-BHC
Beta-BHC
Gamma-BHC (lindane)
Delta-BHC (PCB-polychlorinated biphenyls)
Appendix C. Priority Pollutants
C-l
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September 2010
NPDES Permit Writers' Manual
__
041
042
043
044
045
046
047
048
051
052
053
054
055
056
057
058
059
060
061
062
063
064
065
066
Exhibit C-1 Priority pollutants fror
Pollutant name
4-bromophenyl phenyl ether
Bis(2-chloroisopropyl) ether
Bis(2-chloroethoxy) methane
Methylene chloride (dichloromethane)
Methyl chloride (dichloromethane)
Methyl bromide (bromomethane)
Bromoform (tribromomethane)
Dichlorobromomethane
Chlorodibromomethane
Hexachlorobutadiene
Hexachloromyclopentadiene
Isophorone
Naphthalene
Nitrobenzene
2-nitrophenol
4-nitrophenol
2,4-dinitrophenol
4,6-dinitro-o-cresol
N-nitrosodimethylamine
N-nitrosodiphenylamine
N-nitrosodi-n-propylamin
Pentachlorophenol
Phenol
Bis(2-ethylhexyl) phthalate
n40C
T~
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
;FR Part 423, Appendix A (continued)
Pollutant name E
PCB-1 242 (Arochlor 1242) |
PCB-1 254 (Arochlor 1254)
PCB-1 221 (Arochlor 1221)
PCB-1 232 (Arochlor 1232)
PCB-1 248 (Arochlor 1248)
PCB-1 260 (Arochlor 1260)
PCB-1016 (Arochlor 1016)
Toxaphene
Antimony
Arsenic
Asbestos
Beryllium
Cadmium
Chromium
Copper
Cyanide, Total
Lead
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD)
C-2
Appendix C. Priority Pollutants
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September 2010 NPDES Permit Writers' Manual
Appendix D. New Source Dates by Effluent Guideline
Category
This appendix provides the applicable new source dates used in making new source determinations by
effluent guideline category as provided in Appendix B of the U.S. Environmental Protection Agency
(EPA) memorandum New Source Dates for Direct and Indirect Dischargers1
sent by the directors of EPA's Water Permits Division and the
Engineering and Analysis Division to the Regional Water Division Directors on September 28, 2006.
Section 5.2.2.4 of this manual discusses the determination of whether existing or new source standards
apply.
EPA has promulgated regulations under the Clean Water Act (CWA) that establish effluent limitations
guidelines for existing sources, standards of performance for new sources and pretreatment standards for
new and existing sources. EPA has codified these regulations at Title 40 of the Code of Federal
Regulations (CFR) Subchapter N. As discussed in section 5.2.1 of this manual, EPA has published
effluent guidelines for 56 major industrial categories (over 450 subcategories) since the passage of the
1972 CWA. Those regulations limit the discharge of pollutants to surface waters by point source
dischargers (direct dischargers). The regulations also limit the introduction of pollutants into publicly
owned treatment works (POTWs) by industrial users (indirect dischargers}. The CWA and EPA
regulations define when a source is a new source. A discharger is defined as a new source in CWA
sections 306(a)(2) and 307(c) and §§ 122.2 (for direct dischargers) and 403.3(m) (for indirect
dischargers). In general, a facility is a new source if it begins construction after either the date of
promulgation of new source performance standards applicable to the direct dischargers or the date of
publication of a proposed new source performance standard applicable to an indirect discharger.
Exhibit D-l lists new source dates for direct or indirect dischargers based on regulatory definitions. In
some cases, effluent guidelines in 40 CFR Chapter I, Subchapter N, specify New Source Dates, and these
dates are reported in the table below. If dates are not specified in the rule language, EPA based the date on
the regulatory definitions of new source, which are cited above. EPA's General Pretreatment Regulations
provide that an indirect source is a new source if construction of the source began after the publication of
proposed pretreatment standards for new sources if the proposed standard is later finalized [§ 403.3(m)].
For direct dischargers, § 122.2 states that the New Source date is the proposal date if the standard is
finalized within 120 days after its proposal; otherwise, the New Source date is the promulgation date.
EPA's regulations establish the time and date of EPA's actions for purposes of determining when the
action is subject to judicial review. The regulations, in the case of the CWA, define the date of an EPA
promulgation action as two weeks after the rule appears in the Federal Register (see § 23.2). Before
February 1985, the date on which the final rule was published was considered the promulgation date.
This document is not a regulation itself, nor does it substitute for any requirements under the CWA or
EPA's regulations. Thus, it does not impose legally binding requirements on EPA, states or the regulated
community. While EPA has made every effort to ensure the accuracy of this table, dischargers'
obligations are determined, in the case of direct dischargers, by the terms of their NPDES permit and the
CWA and EPA's regulations, and, in the case of indirect dischargers, by permits or equivalent control
Appendix D. New Source Dates by Effluent Guideline Category D-l
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NPDES Permit Writers' Manual
mechanisms issued to POTW industrial users and the CWA and EPA regulations. Nothing in this
document changes any statutory or regulatory requirement. If the discussion in this memorandum
conflicts with any permit or regulation, this document would not be controlling.
Exhibit D-1 New source dates by effluent category
40
CFR
Part
467
427
461
407
408
458
411
437
434
465
412
451
468
405
469
413
457
424
418
426
406
454
460
447
Category
Aluminum Forming
Asbestos Manufacturing
Battery Manufacturing
Canned and Preserved
Fruits and Vegetables
Processing
Canned and Preserved
Seafood Processing
Carbon Black Manufacturing
Cement Manufacturing
Centralized Waste
Treatment (CWT)
Coal Mining
Coil Coating
Concentrated Animal
Feeding Operations (CAFO)
Concentrated Aquatic
Animal Production
Copper Forming
Dairy Products Processing
Electrical and Electronic
Components
Electroplating
Explosives Manufacturing
Ferroalloy Manufacturing
Fertilizer Manufacturing
Glass Manufacturing
Grain Mills
Gum and Wood Chemicals
Hospitals
Ink Formulating
New source date for
direct dischargers
SubpartsA-F: 10/24/83
SubpartsA-K: 10/30/732
Subparts A-G: 03/09/84
SubpartsA-H: 03/21/74
Subparts A-J, N: 06/26/74
Subparts O-AG: 12/01/75
Subparts A-D: 01/09/78
Subparts A-C: 02/20/74
Subparts A-D: 01/05/01
Subparts B-E, H: 05/04/843
Subpart G: 02/22/024
Subparts A-C: 12/01/82
Subpart D: 11/17/83
Subparts A-B: 02/14/74
Subparts C-D: 04/1 4/035
Subparts A-B: 09/07/04
Subpart A: 08/15/83
Subparts A-L: 05/28/74
Subparts A-B: 04/08/83
Subparts C-D: 12/14/83
Not Applicable6
Not Applicable
Subparts A-C: 02/22/74
Subparts A-D: 04/08/74
Subpart E: 01/16/76
Subparts F-G: 10/07/748
Subpart A: 01/22/74
Subparts B-D: 02/14/74
Subparts E-G: 02/14/74
Subparts H, J-M: 01/16/75
Subparts A-J: 1 2/04/73 10
Not Applicable
Not Applicable
Subpart A: 07/28/75
New source date for indirect
dischargers
Subparts A-F: 11/22/82
Not Applicable
Subparts A-G 11/10/82
Not Applicable
Not Applicable
Subparts A-D: 05/18/76
Not Applicable
Subparts A-D: 01/13/99
Not Applicable
Subparts A-C: 01/12/81
Subpart D: 02/10/83
Subpart B: 09/07/73
Not Applicable
Subpart A: 11/12/82
Not Applicable
Subparts A-B: 08/24/82
Subparts C-D: 03/09/83
See Metal Finishing7
Not Applicable
Not Applicable
Subparts A-D9: 12/07/73
Subpart E: 01/16/76
Subparts F-G: 10/07/74
Subparts H, K-M: 08/21/74
Subpart A: 12/04/73
Not Applicable
Not Applicable
Subpart A: 02/26/75
D-2
Appendix D. New Source Dates by Effluent Guideline Category
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NPDES Permit Writers' Manual
Exhibit D-1 New source dates by effluent category (continued)
40
CFR
Part
415
420
445
425
432
433
464
438
436
471
421
435
440
Category
Inorganic Chemicals
Iron and Steel
Manufacturing
Landfills
Leather Tanning and
Finishing
Meat and Poultry Products
Metal Finishing
Metal Molding and Casting
Metal Products and
Machinery
Mineral Mining and
Processing
Nonferrous Metals Forming
and Metal Powders
Nonferrous Metal
Manufacturing
Oil and Gas Extraction16
Ore Mining and Dressing
New source date for
direct dischargers
Subparts B-F, H, K-N, P,
Q, T, V, W, AJ [CuSO4
manufacturing], AH, AP,
AU [NiSO4
manufacturing], BB: 06/29/82
Subparts AJ [except
CuSO4 manufacturing],
AU [except NiSO4
manufacturing], BL - BO: 08/22/84
Subparts A-B: 11/1 8/0211
Subpart C: 05/27/82
Subpart D, Semi-Wet: 10/31/02
Subpart D, Other: 05/27/82
Subparts E-L: 05/27/82
Subpart M: 10/31/02
Subparts A-B: 02/02/00
Subparts A, B, D-l: 11/23/82
Subpart C: 04/04/88
Subparts A-D, Small
Facilities: 02/28/7413
Subparts A-D, Other: 09/22/04
Subparts E-l, Small
Facilities: 01/03/7514
Subparts E-l, Other: 09/22/04
Subpart J-L: 09/22/04
Subpart A: 07/15/83
Subparts A-D: 11/13/85
Subpart A: 06/12/0315
Not Applicable
Subparts A-J: 09/06/85
Subparts B-l (except
molybdenum acid plants),
K-M: 03/08/84
Subparts N-AE,
molybdenum acid plants
insubpartl: 10/04/85
Subpart J: 02/04/88
Subparts C (Onshore), D
(Coastal), and E
(Agricultures Wildlife): 03/04/93
Subparts A and D
(Synthetic-Based Drilling
Fluids): 02/05/01
Subparts A-F, J, M: 12/03/82
New source date for indirect
dischargers
Subparts B-F, H, K-N, P, Q,
V, AH, AJ [CuSO4
manufacturing], AP, AU
[NiSO4 manufacturing], BB: 07/24/80
Subparts T, AA, AC, AE, Al,
AJ
[except CuSO4
manufacturing], AL, AN, AQ,
AR, AU [except NiSO4
manufacturing], AX, BC, BH,
BK-BO: 10/25/83
Subparts A-B: V"8102
Subpart C: 01/07/81
Subpart D, Semi-Wet: -Jo/oy/nn
Subpart D, Other: MMM
Subparts E-F, H-J.L: ° °
Subpart M: 81
Not Applicable
Subpart A, B, D-l: 07/02/79
Subpart C: 01/21/87
Not Applicable
Subpart A: 08/31/82
Subparts A-D: 11/15/82
Not Applicable
Not Applicable
Subparts A-J: 03/05/84
Subparts B-l (except
molybdenum acid plants),
K-M: 02/17/83
Subparts N-AE, molybdenum
acid plants in subpart I: 06/27/84
Subpart J: 01/22/87
Subpart D: 02/17/95
Not Applicable
Appendix D. New Source Dates by Effluent Guideline Category
D-3
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NPDES Permit Writers' Manual
Exhibit D-1 New source dates by effluent category (continued)
40
CFR
Part
414
446
443
455
419
439
422
459
463
466
430
428
417
423
409
Category
Organic Chemicals,
Plastics, and Synthetic
Fibers
Paint Formulating
Paving and Roofing
Materials (Tars and Asphalt)
Pesticide Chemicals
Petroleum Refining
Pharmaceutical
Manufacturing
Phosphate Manufacturing
Photographic
Plastics Molding and
Forming
Porcelain Enameling
Pulp, Paper, and
Paperboard
Rubber Manufacturing
Soap and Detergents
Manufacturing
Steam Electric Power
Generation
Sugar Processing
New source date for
direct dischargers
SubpartsB-H: 11/19/87
SubpartA: 07/28/75
Subparts A-D: 07/28/75
SubpartsA-B: 10/12/93
Subparts C, E: 11/20/96
Subparts A-E: 10/18/82
Subparts A-D: 11/20/9817
Subparts D-F: 06/23/76
Not Applicable
Subparts A-C: 12/17/84
Subparts A-D: 11/24/82
Subparts B, E: 06/1 5/9818
Subparts A, C, D, F, G,
I-L: 11/18/82
Subparts A-D: 02/21/74
Subparts E-J: 01/10/75
Subparts A-S: 4/12/74
1 1/1 9/82 19
SubpartA: 1/31/74
Subparts B, C: 12/07/7320
New source date for indirect
dischargers
Subparts B-H: 03/21/83
Subpart A: 02/26/75
Subparts A-D: 01/10/75
Subparts A-B: 04/10/92
Subparts C, E: 04/14/94
Subparts A-E: 12/21/79
Subparts A-D: 05/02/95
Not Applicable
Not Applicable
Not Applicable
Subparts A-D: 01/27/81
Subparts B, E: 12/17/93
Subparts A, C, D, F, G, I-L: 01/06/81
Subparts E-K: 08/23/74
Subpart Q: 12/26/73
Subparts O, P, R: 02/20/75
10/14/80
Not Applicable
1 Boomazian, Linda and Mary Smith. 2006. New Source Dates for Direct and Indirect Dischargers. U.S. Environmental
Protection Agency, Office of Water Memorandum. September 28, 2006. .
2 The rule was finalized within 120 days of its October 30, 1973, proposal (38 FR 22606).
3 The New Source date is specified in 40 CFR 434.1 l(j)(l).
4 The New Source date is specified in 40 CFR 434.1 l(j)(l).
5 New Source date derived from the 10-year protection period [see 40 CFR 412.35(d) and 412.43(d)].
6 Direct dischargers formerly regulated under Part 413 are now regulated under Part 433 (metal finishing).
7 Pretreatment categorical standards in Part 413 currently apply only to job shop electroplaters and independent printed circuit
board manufacturers that were in existence before the New Source date for Part 433 (metal finishing). Job shop electroplaters and
independent printed circuit board manufacturers that are "New Sources" must comply with PSNS in Part 433. Except for these
"existing" job shop electroplaters and independent printed circuit board manufacturers, all other operations formerly subject to
Part 413 are now subject to Part 433.
8 The rule was finalized within 120 days of its October 7, 1974, proposal.
9 Section 41 8.46 (the PSNS under Subpart D) was suspended until further notice, at 40 FR 26275, June 23, 1975, effective July
20, 1975.
10 The rule was finalized within 120 days of its December 4, 1973, proposal (38 FR 33438).
Endnotesfor this chapter continued on the next page.
D-4
Appendix D. New Source Dates by Effluent Guideline Category
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September 2010 NPDES Permit Writers' Manual
11 Date specified in 40 CFR 420.14(a)(2), 420.16(a)(2), 420.24(b), and 420.26(a)(2).
12 See previous footnote.
13 The 2004 Amendment did not revise NSPSs for small meat products facilities in Subparts A-I, so the 2004 New Source date
does not affect these facilities.
14 See previous footnote.
15 Date specified in 40 CFR 438.15.
16 See promulgated standards at 40 CFR 58 FR 12505 and 66 FR 6850 for complete information on the applicability of New
Source standards.
17 New Source date derived from the 10-year protection period [see 40 CFR439.15(c), 439.35(c), and439.45(b)].
18 Date specified in 40 CFR 430.25(b) and 430.55(b). Refer to these sections for additional information regarding the
applicability of NSPSs.
19 NSPS promulgated were not removed via the 1982 regulation; therefore wastewaters generated by Part 423-applicable sources
that were New Sources under the 1974 regulations are subject to the 1974 NSPS. The New Source date for the 1974 regulations
was 10/8/1974.
20 The rule was finalized within 120 days of its December 7, 1973, proposal (38 FR 33846).
Appendix D. New Source Dates by Effluent Guideline Category D-5
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