This page intentionally left blankUnited States Environmental Protection Agency Office of Water Washington, DC



# 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 deve loping NPDES permits. EPA may change this guid ance 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

## Acknowledgements

David Hair and Pravin Rana
, United States Environmental Protection Agency (EPA), Offi ce 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, Of fice of Wastewater Management, Wa ter 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 Utting

 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 Technolo gy, Standards and Health Protection Division

 Meghan Hessenauer, Office of Science and Technology, Engineering and Anal ysis Division

 Carey Johnston, Office of Science and Technology, Engi neering and Anal ysis Division

 Dick Reding, Office of Science and Tec hnology, Engineering and Analysis Division

 Marla Smith, Office of Science and Technology, Engineering and Analysis Division

Additional EPA Contributors

 Robert Hargrove, Office of Enforcement and Compliance Assurance, Off ice of Federal Activities, Washington, DC

 Robert Klepp, Office of Enfo rcement 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 Re gulatory Support, Fairfax, VA managed prod uction and technical support for development of the manual.
Additional contributors from Tetra Tech, Inc. for developmen t, design, and final production of this document include

 Krista Carlson

 Jim Collins

 Chuck Durham

 Steve Geil

 Shari Goodwin  John Kosco

 I-Hsin Lee

 Gregory Mallon

 Betty Peterson  Gregory Savitske

 Peter Sherman

 Kristin Schatmeyer

 Jeff Strong

Cover and Exhibit 1-2 Photo Credits

1. Natchez-Tennessee Tombigbee Waterway—Peter Cada, Tetra Tech, Inc. 2. Municipal Publicly Owned Treatment Wo rks—Ohio Environmental Protection Agency 3. Municipal Separate Storm Sewer System—USDA NRCS 4. Concentrated Animal Feeding Operation—USDA NRCS 5. Incidental Vessel Discharges—Smiths onian Environmental Research Center, National Ballast Information Clearinghouse 6. Non-Municipal (Industrial)—EPA 7. Construction Stormwater—Barry Tonning, Tetra Tech, Inc. 8. Combined Sewer Overflow—EPASeptember 2010 NPDES Permit Writers’ Manual

i 

## Contents

Introduction to the Ma nual ..................................................................................................... ........ vii Purpose of this Manual

......................................................................................................... ....vii Publications Refere nced ........................................................................................................ .. viii Legislative and Regula tory Cita tions........................................................................................ vii i Electronic NPDES Information ................................................................................................... ix

CHAPTER 1. Development of the Clean Water Act and the NPD ES Program ........................ 1-1 1.1 History of Water Pollution C ontrol in the Un ited Stat es.................................................. 1-1 1.2 Evolution of t he NPDES Pr ogram .................................................................................. 1-3 1.3 NPDES Statutor y Framewor k ........................................................................................ 1-5 1.3.1 Perm it ................................................................................................................ 1-5 1.3.2 Pollu tant............................................................................................................. 1-6 1.3.3 Waters of th e United St ates............................................................................... 1-6 1.3.4 Point Source ...................................................................................................... 1- 7

CHAPTER 2. Regulatory Framework and Program Areas of the NPD ES Program ................ 2-1 2.1 Regulatory Framework of the NPDES Program ............................................................. 2-1 2.2 Federal and State Responsibilit ies ................................................................................ 2-2 2.2.1 State NPDES Progr am Author ity....................................................................... 2-2 2.2.2 Roles and Responsibilities of the Federal and State Au thoritie s ....................... 2-4 2.3 NPDES Progr am Areas ................................................................................................. 2-5 2.3.1 NPDES Program Areas Applic able to Municipal Source s ................................. 2-5 2.3.2 NPDES Program Areas Applicabl e to Non-Municipal Source s........................ 2-10 2.4 Major/Minor Fac ility Designat ion.................................................................................. 2-17 2.5 Growth and Change in the NPDES Program ............................................................... 2-17

CHAPTER 3. Overview of the NPDES Permitting Pr ocess ....................................................... 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 Majo r Components of a Perm it ...................................................................................... 3-2 3.3 Overview of the Development and Issuance Process for NP DES Individual Permits .... 3-3 3.4 Overview of the Develo pment and Issuance Process for NPDES General Permits ...... 3-5

CHAPTER 4. NPDES Permit Appli cation Pro cess..................................................................... 4-1 4.1 Who Applies for an NPDES Perm it?.............................................................................. 4-1 4.2 Applicati on Deadlin es .................................................................................................... 4- 3 4.3 Application Forms and Requirements for Indi vidual Perm its.......................................... 4-3 4.3.1 Form 1: General Informat ion.............................................................................. 4-5 4.3.2 Form 2A: New and Existing PO TWs.................................................................. 4-5 4.3.3 Form 2S: New and Existing TW TDS ................................................................. 4-6 4.3.4 Form 2B: New and Existing Conc entrated Animal Feeding Operations (CAFOs) and Concentrated A quatic 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, Co mmercial, Mining, and Silvicultural Discharges of Proces s Wastewat er................................................................... 4-8 4.3.7 Form 2E: Manufacturing, Commercia l, Mining, and Silvicultural Facilities that Discharge Only Non- Process Wast ewater .................................................. 4-8September 2010 NPDES Permit Writers’ Manual

4.3.8 Form 2F: Stormwater Discharges As sociated with Industr ial Activities ............. 4-9 4.3.9 Stormwater Discharges Associat ed with Constructi on Activi ty .......................... 4-9 4.3.10 Stormwater Dischar ges from Sma ll MS4s ....................................................... 4-11 4.3.11 Cooling Water In take Struct ures...................................................................... 4-11 4.4 Requirements for NPDE S General Pe rmits ................................................................. 4-12 4.5 Applicati on Review ...................................................................................................... 4-1 3 4.5.1 The Complete Applicati on................................................................................ 4-14 4.5.2 Common Omissions in Applicat ions ................................................................ 4-14 4.5.3 The Accurate Applicatio n................................................................................. 4-16 4.6 Facility Inform ation Revi ew.......................................................................................... 4-17 4.6.1 Permit F ile Revi ew........................................................................................... 4-17 4.6.2 Facility Si te Visi ts............................................................................................. 4-19 4.7 Confidential In formatio n............................................................................................... 4-21

CHAPTER 5. Technology-Based Efflue nt Limita tions .............................................................. 5-1 5.1 Technology-based Effluent Limitation s for POTW s ....................................................... 5-2 5.1.1 Secondary and Equivalent to Secondary Treatment Standards ........................ 5-2 5.1.2 Adjustments to Equival ent to Secondar y Standards .......................................... 5-4 5.1.3 Applying Secondary Treatment Standards, Equivalent to Secondary Treatment Standards, and Adjusted Standa rds................................................. 5-6 5.2 Technology-Based E ffluent Limitations for Industrial (Non-POTW) Dischargers ......... 5-13 5.2.1 Effluent Gu idelines .......................................................................................... 5-14 5.2.2 Applying Effluent Guidelines through NPDES Permits .................................... 5-23 5.2.3 Case-by-Case TBELs fo r Industrial Di schargers ............................................. 5-44

CHAPTER 6. Water Quality-Based Effl uent Limita tions ........................................................... 6-1 6.1 Determine Applicable Wa ter Quality St andards ............................................................. 6-2 6.1.1 Components of Wate r Quality St andards .......................................................... 6-3 6.1.2 Water Quality Standar ds Modifica tions.............................................................. 6-9 6.1.3 Water Quality Standar ds Implement ation

........................................................ 6-11 6.2 Characterize the Effluent and the Receivi ng Water

..................................................... 6-12 6.2.1 Step 1: Identify Pollutants of Concern in the E ffluent....................................... 6-13 6.2.2 Step 2: Determine Whether Wa ter Quality Standards Provide for Consideration of a Dilution Allowance or Mi xing Zone ..................................... 6-15 6.2.3 Step 3: Select an Approach to Model Effluent and Receiving Water Interacti ons...................................................................................................... 6-16 6.2.4 Step 4: Identify Effluent and Receiving Water Critical C onditions .................... 6-16 6.2.5 Step 5: Establish an Appropriate Dilution Allowance or Mixing Z one .............. 6-20 6.3 Determine the N eed for WQBEL s................................................................................ 6-22 6.3.1 Defining Reasonabl e Potentia l ........................................................................ 6-23 6.3.2 Conducting a Reas onable Potential Analys is Using Data ............................... 6-23 6.3.3 Conducting a Reas onable Potential Analys is without Data ............................. 6-30 6.4 Calculate Paramete r-specific WQ BELs ....................................................................... 6-31 6.4.1 Calculating Paramete r-specific WQBELs from A quatic Life Cr iteria ................ 6-31 6.4.2 Calculating Chemical -specific WQBELs based on Human Health Criteria for Toxic Poll utants .......................................................................................... 6-35 6.5 Calculate Reas onable Potential and WQ BELs for WE T .............................................. 6-36 6.5.1 Types of WET Test s ........................................................................................ 6-36 6.5.2 Expressing WET Limitati ons or Test Results ................................................... 6- 37 6.5.3 Determining the Need for WET Limi tations ...................................................... 6-38 6.6 Antidegradati on Review ............................................................................................... 6-40 6.6.1 Tier 1 Impl ementatio n...................................................................................... 6-41 6.6.2 Tier 2 Impl ementatio n...................................................................................... 6-41 6.6.3 Tier 3 Impl ementatio n...................................................................................... 6-42

iiSeptember 2010 NPDES Permit Writers’ Manual

CHAPTER 7. Final Effluent Limitation s and Anti-backs liding.................................................. 7-1 7.1 Determining Final E ffluent Limita tions............................................................................ 7-1 7.2 Applying Anti-backslid ing Requirem ents........................................................................ 7-2 7.2.1 Anti-backsliding St atutory Prov isions ................................................................. 7-2 7.2.2 Anti-backsliding R egulatory Prov isions .............................................................. 7-4

CHAPTER 8. Monitoring and Repor ting Conditi ons ................................................................. 8-1 8.1 Establishing Moni toring Condi tions................................................................................ 8-1 8.1.1 Purposes of Monitori ng...................................................................................... 8-2 8.1.2 Monitoring Location ........................................................................................... 8-2 8.1.3 Monitoring Frequency ........................................................................................ 8-5 8.1.4 Sample Co llection .............................................................................................. 8-7 8.2 Additional Monitoring Requi rements and WET Testing ................................................. 8-9 8.2.1 Biosolids (S ewage Sludge )................................................................................ 8-9 8.2.2 Combined Sewer Overflows (CSOs) and Sanitary Sewer Overflows (SSOs).. 8-11 8.2.3 Stormwater Monito ring Consider ations ............................................................ 8-11 8.2.4 WET Moni toring ............................................................................................... 8-12 8.3 Analytical Met hods ....................................................................................................... 8- 13 8.4 Reporting Monito ring Result s....................................................................................... 8-14 8.5 Recordkeeping Requirement s ..................................................................................... 8-14

CHAPTER 9. Special Condi tions ................................................................................................ 9-1 9.1 Special Conditions Potentially A pplicable to Any Type of Dischar ger............................ 9-1 9.1.1 Additional Monitoring and Special St udies ........................................................ 9-2 9.1.2 Best Management Pr actices (B MPs)................................................................. 9-3 9.1.3 Complianc e Schedules ...................................................................................... 9-8 9.2 Special Conditions for Municipal Fac ilities ..................................................................... 9-9 9.2.1 The National Pret reatment Pr ogram................................................................ 9-10 9.2.2 Biosolids (S ewage Sludge ).............................................................................. 9-13 9.2.3 Combined Sewer Ov erflows (C SOs) ............................................................... 9-15 9.2.4 Sanitary Sewer Overflows ( SSO s)................................................................... 9-20

CHAPTER 10. Standard Conditions of NPDES Perm its............................................................ 10-1 10.1 Types of Standar d Conditi ons...................................................................................... 10-1 10.2 Other Standard Condition s .......................................................................................... 10-3

CHAPTER 11. NPDES Permit Admi nistrati on............................................................................ 11-1 11.1 Other Federal Laws Applic able to NPDES Permits ..................................................... 11-1 11.1.1 Endangered S pecies Ac t ................................................................................. 11-1 11.1.2 National Environm ental Policy Act................................................................... 11-2 11.1.3 National Historic Pres ervation Act Am endments ............................................. 11-3 11.1.4 Coastal Zone Management Ac t ....................................................................... 11-3 11.1.5 Wild and Sceni c Rivers Act.............................................................................. 11-3 11.1.6 Fish and Wildlife Coordination Act................................................................... 11-4 11.1.7 Essential Fish H abitat Provis ions .................................................................... 11-4 11.2 Documentation for Development of the Dra ft Permit ................................................... 11- 4 11.2.1 Administrati ve Reco rd ..................................................................................... 11-8 11.2.2 Fact Sheets and Stat ements of Ba sis.............................................................. 11-8 11.3 Items to Address before I ssuing a Final Permit ......................................................... 11-10 11.3.1 Public Notice.................................................................................................. 11-11 11.3.2 Public Co mments .......................................................................................... 11-12 11.3.3 Public H earings ............................................................................................. 11-13 11.3.4 Environmental Justic e Considerat ions........................................................... 11-14 11.3.5 EPA and State/Tribal Roles in Reviewing Draft Permits................................ 11-14

iiiSeptember 2010 NPDES Permit Writers’ Manual

11.3.6 Schedule for Final Pe rmit Issuanc e ............................................................... 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 Term ination ........................................................................................ 11-20 11.4.4 Permit Tr ansfer.............................................................................................. 11-21 11.5 Permit Compliance and Enforcem ent ........................................................................ 11-21 11.5.1 Compliance M onitoring .................................................................................. 11-22 11.5.2 Quarterly Noncom pliance Repor ts................................................................. 11-23 11.5.3 Enforc ement .................................................................................................. 11-25 Appendix A. Acronyms, Abbreviations and Glo ssary............................................................. A-1 A.1 Acronyms and A bbreviati ons ......................................................................................... A-1 A.2 Glo ssary................................................................................................................... ......A-4 Appendix B. Index to the CWA and NPDES Regulat ions........................................................ B-1 B.1 Index to Sections of the CWA ........................................................................................B-1 B.2 Index to NPD ES Regulati ons......................................................................................... B-3 Appendix C. Priority Pollu tants................................................................................................. C-1 Appendix D. New Source Dates by Effluent Guideline Ca tegory ........................................... 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 Exhibit 2-1 R egulations re lated to the NPDES program ...................................................................2-2 Exhibit 2-2 Federal NPDES r egulations (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 progr am areas and applicable regulations ........................................................2-6 Exhibit 3-1 Permit components ........................................................................................................3-3 Exhibit 3-2 Major steps to develop an d issue NPDES individual permits .........................................3-4 Exhibit 3-3 Major steps to devel op an d issue NPDES general pe rmits ............................................3-5 Exhibit 4-1 Effect of court decisions on § 122.3

............................................................................... 4-2 Exhibit 4-2 When to app ly for an NPDES permit ..............................................................................4-3 Exhibit 4-3 EPA applicatio n requireme nts for NPDES individual permits

......................................... 4-4 Exhibit 4-4 Permit applic ation review pr ocess

................................................................................ 4-13 Exhibit 4-5 Consideration s for an application to be complete .........................................................4-15 Exhibit 4-6 Example of required testing during a pplication review .................................................4-16 Exhibit 4-7 C onsideration s 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 tr eatment standards ................................................................5-3 Exhibit 5-4 State-specific adjusted TSS requirements .....................................................................5-5

ivSeptember 2010 NPDES Permit Writers’ Manual

Exhibit 5-5 Steps to establish technol ogy-based discharge limitations for POTWs ..........................5-6 Exhibit 5-6 Effluent limitations calcul ated from secondary treatment standards

............................... 5-7 Exhibit 5-7 POTW mass based limitatio n ca lculation equation and example calculations

............... 5-8 Exhibit 5-8 Summary of C WA 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 efflue nt guidelines to direct discharges .........................................5-23 Exhibit 5-11 Table of existing poi nt source categori e s (June 2010) ...............................................5-24 Exhibit 5-12 Examples of identifying a pp licable effluent guidelin es using SIC codes .....................5-25 Exhibit 5-13 Examples of identifying the s ubcategor y with the applic able effluent guideline s ........5-27 Exhibit 5-14 Example of calculating mass-based effluent limitation from prod uction-norma lized effluent guidelines ........................................................................................................5- 31 Exhibit 5-15 Example nar rative req uirement fr om the Concentrated A quatic Animal Production effluent guideline—Subpart 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 r egarding applicability of effluent guidelines ........................................................................................................5- 34 Exhibit 5-18 Building block approach for applying e ffluent 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 consider ed when devel opin g 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-t o-permits process ........................................................................................6-2 Exhibit 6-3 Aquatic life criteria example : Cadmium (dissolved) ........................................................6-5 Exhibit 6-4 Hu man health criteria example: Dichlorobromomethane ................................................6-7 Exhibit 6-5 Steps for characterizi ng th e effluent and receiving w ater .............................................6-13 Exhibit 6-6 Parts of a TMDL

........................................................................................................... 6- 14 Exhibit 6-7 Example of lognormal distribution of effluent pollutan t conc entrations and projection of critical con c entration (C d ) .........................................................................................6-18 Exhibit 6-8 Regulatory mixing z ones for aquatic life criteria ...........................................................6-21 Exhibit 6-9 Examples of maximum mixing zone si zes or dilution allowances under incomplete mixing conditions by waterbod y type ...........................................................................6- 22 Exhibit 6-10 Steps of a re asonable pot ential analysis with available data ......................................6-23 Exhibit 6-11 Simple mass-balance e q uation ..................................................................................6-24 Exhibit 6-12 Example of receiving water conc entrations in an incomplete mixing situation determined u sing an incomplete mixing water quality model

....................................... 6-26 Exhibit 6-13 Mass-balance equation for reasonable pot ential analysis for conservative pollutant unde r conditions of rapid and complete mixing

............................................................ 6-27 Exhibit 6-14 Example of applying mass-bal ance equation to conduct reasonable potential analysis for conservative pollutant und er conditions of rapid and complete mixing .....6-28 Exhibit 6-15 Reasonable potential determinat ion in an incomplete mixing situation ......................6-29

vSeptember 2010 NPDES Permit Writers’ Manual

vi Exhibit 6-16 Calculating parameter-spec ific WQBELs from aquatic life criteria ..............................6-31 Exhibit 6-17 Example of applying mass-balance eq uation to calculate WLAs for conservative pollutant under conditions of rapid and complete mixing

............................................. 6-33 Exhibit 6-18 Example of lognormal distribut ion of effluent pollut ant concentrations and calculation of WLA .......................................................................................................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 fo r a WET reasonable potential analysis ...........6-39 Exhibit 7-1 D e veloping 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 specifyi ng monitoring locations in permits .................................................8-3 Exhibit 8-2 Visual interpretation of time -proportional composite monitoring

..................................... 8-8 Exhibit 8-3 Visual interpre tation of flow-proportional composite monitoring

..................................... 8-8 Exhibit 8-4 Minimum requi rements for sewage sludge monitoring, based on method of sludge use or disposal .............................................................................................................8- 10 Exhibit 9-1 Example BMP plan require ment

..................................................................................... 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 pr ocess for EPA-issued NPDES permits ............................................11-6 Exhibit 11-4 Typical administrative pro cess for state-issued NPDES permits ................................11-7 Exhibit 11-5 Elements of the adminis trative records for a draft permit ...........................................11-8 Exhibit 11-6 Requir ed elements of a fact sheet ..............................................................................11-9 Exhibit 11-7 Actions for whic h public notice is required ................................................................11-11 Exhibit 11-8 Contents of the public notice ....................................................................................11-12 Exhibit 11-9 Elements of the adminis trative 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-2September 2010 NPDES Permit Writers’ Manual

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## 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’ Manual 1

< www.epa.gov/npdes/pubs/owm0243.pdf >, which updated the 1993 Training Manual for NPDES Permit Writers 2 < www.epa.gov/npdes/pubs/owm0339.pdf >.
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 pr ogram on which guidance for specific areas of the program (e.g., stormwater, concentrated animal f eeding 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 au thorized state, territory, or tribe (hereafter state ) will tailor specific aspects of its NPDES permitting pr ocedures to address state and local laws and sitespecific concerns and conditions.
The specific objectives and functions of this manual are as follows:

 Provide an overview of the scope and the stat utory 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.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 re ference document. Rather, it establishes the framework for NPDES permit development and should be supple mented, where necessary, by additional EPA and state regulations, policy, and detailed guidance a pplicable to specific types of dischargers and circumstances. To that end, this manual identifies a nd references relevant regul ations, policy, and other guidance documents throughout the text.



## Publications Referenced
This manual provides links to publications availabl e 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) < www.epa.gov/safewater/resource/ > 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:

< center.water-resource@epa.gov >.

 EPA Library Services and Repositories < www.epa.gov/natlibra/libraries.htm > EPA’s library services and repositories provide access to information about the environment and related scientific, technical, management, and policy information. Library services

< www.epa.gov/natlibra/lib rary_services.html > are delivered through the National Library Network

< www.epa.gov/natlibra/index.html >.

 National Service Center for Environmental Publications (NSCEP) < www.epa.gov/ncepihom/ > NSCEP, formerly NCEPI, maintains and distribut es 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: ncepimal@one.net

.

 National Technical Information Service (NTIS) < www.ntis.gov/ > NTIS is the largest central resource for governme nt-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. a nd then followed by the section number. Example: 16 U.S.C. 1531 et seq . and 33 U.S.C. §§ 1251-1387.

viiiSeptember 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 part—a whole number) or the number of the subsection (if it is a subpart/subsection). For sub sequent 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 da ta are available to help permit writers draft NPDES permits. Tools have been created to assist permit wr iters with specific aspects of permit development and are discussed in their respective sections. The electr onic 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 < www.epa.gov/npdes > 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 referenc es 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 informa tion provided on websites outside the EPA Website < www.epa.gov >.
WPD also has prepared several websites and other r esources 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 develope d 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 stor e 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 informati on technology applications to manage the process of permitting.

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### 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 st ates and EPA Regions. OECA, along with its regional, state, tribal and local counterparts, is respons ible for tracking and maintaining enforcement and compliance activities, monitoring and enforcement an d compliance status of the regulated community, and reviewing and evaluating progr am performance. OECA also maintains national data systems to support program management and ove rsight 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. Si nce 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)

< https://icis.epa.gov/icis >, 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 electr onic 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 el ectronic 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 Perm it Writers’ Manual . EPA-833-B-96-003. U.S. Environmental Protection Agency, O ffice of Water, Washington, DC. < www.epa.gov/npdes/pubs/owm0243.pdf >. Separate sections of this document are also ava ilable on the NPDES Website by going to < www.epa.gov/npdes >, 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.

< www.epa.gov/npdes/pubs/owm0339.pdf >.September 2010 NPDES Permit Writers’ Manual

Chapter 1: Development of the Clean Water Act and the NPDES Program 1-1 

## 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 Po llutant Discharge Elimination System (NPDES) Program.



## 1.1 History of Water Pollution Co ntrol in the United States
Major water pollution control legislation in the United States dates back to the end of the 19 th 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)

The first major water pollution control statute was the 1899 Rivers and Harbors Act , which established permit requirements to prevent unauthorized obstructi on 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 heal th protection. The act allotted funds to state and local governments for water pollutio n 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 comprehensiv e 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 ma jor 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 pr oviding funding to municipalities to construct wastewater treatment plants.
Just a few years later, Congress further strengthene d federal water pollution control laws by enacting the 1965 Water Quality Act . This law created the Federal Wate r Pollution Control Administration andSeptember 2010 NPDES Permit Writers’ Manual

represented a major regulatory advancement in water pollution control by requiring states to develop water quality standards for interstate waters by 196 7. 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 escala ting public concern and increased public spending, only about half of the states developed water quality sta ndards by 1971. Furthermore, enforcement of the federal statute was minimal because the regulatory ag encies 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 ci vil 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 aut hority of section 13 of the 1899 Rivers and Harbors Act (a section also known as the Refuse Ac t). 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 admini ster 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 guide lines on effluent quality. States would be asked to examine permit applications and advise EPA whethe r 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 i ssue 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 recodification and revision of past federal water po llution 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 clea nup) 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 navigabl e 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 of fish, shellfish, and wild life and provides for recreation in and on the water” by July 1, 1983. That goal is commonly referred to as the fishable, swimmable goal of the act and is one

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of the factors that states must consider in the de velopment of their water quality standards. The water quality standards are implemented in NPDES permits through water quality-b ased effluent limitations (WQBELs). By prohibiting the discharge of a pollutant or pollutants from a point source to waters of the United States—except 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 secti on 1.2 below with regard to their impact on the evolution of the NPDES program. Exhibit B-1, Index to Sections of the CWA, in Appendix B of this document matches the key sections of the CW A to their appropriate reference in the United States Code (U.S.C.). This information is at U.S.C., Title 33 (Navigation and Navi gable Waters), Chapter 26 (Water Pollution Prevention and Control), 1251-1387 (33 U.S.C. §§ 1251-1387)

< www.epa.gov/lawsregs/laws/cwa.html >.



## 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 fra mework in detail. A permit provides two types of control: technology-based limitations (based on the t echnological 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 st andards 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 di scharge of all pollutants. [CWA section 301 (b)(2)(A)]. Compliance deadlines for BPT and BAT were establis hed as of July 1, 1977, and July 1, 1983, respectively.
In addition to BPT and BAT requirements for i ndustrial 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-theart control technologies for new sources because the pe rmittees have the opportunity to install the most efficient production processes and the latest in tr eatment 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 limitati ons 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 pol lutants with oil and grease added to § 401.16 in 1979. The following are formally designated as conventional pollutants:

 Five-day Biochemical Oxygen Demand (BOD 5 ).

 Total Suspended Solids (TSS).

 pH.

 Fecal Coliform.

 Oil and Grease.
The 1972 FWPCA Amendments, however, also required th at EPA publish a list of toxic pollutants within 90 days and propose effluent standards for those pollu tants 6 months later. EPA was not able to meet those requirements because of the lack of inform ation 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 throug h the authorities of the FWPCA Amendments.
The provisions of the consent decree were inco rporated into the framework of the 1977 FWPCA Amendments, formally known as the CWA. This st atute shifted the emphasis of the NPDES program from controlling conventional pollutants to controlling toxic pollutant discharges. CWA section 307(a)(1) 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 toxi c 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 pretreat ment program. The 1977 law created a new pollutant category, nonconventional pollutants, that include d 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 d eadline for BAT for toxic pollutants to July 1, 1984, established a three-year deadline for complianc e with BAT for newly listed toxics, and gave industries until as late as July 1, 1987 to meet BA T 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 contro l of conventional pollutants. Finally, among other changes, the 1977 CWA authorized EPA to approve lo cal 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 limita tions were not able to prevent the discharge of toxic substances in toxic amounts in all waterw ays. To complement its work on technology-based limitations, EPA initiated a national policy in Febr uary 1984 to control toxics using a water quality approach. On February 4, 1987, Congress amended th e 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 pr epare individual control strategies to reduce toxics from point and nonpoint sources to meet the water qua lity standards. Among other measures, those plans were expected to address control of po llutants beyond technology-based levels.
The 1987 WQA further extended the compliance dead line 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 stormwat er dischargers. In addition to meeting water qualitybased 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 engin eering 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 th an 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, un der 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, po llutant, waters of the United States, and point source) is defined is the key to de fining 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 th e permit. An NPDES permit typically is a license for a facility to discharge a specified amount of a pollu tant into a receiving water under certain conditions; however, NPDES permits can also authorize facilities to process, incinerate, landfill, or beneficially use

Chapter 1: Development of the Clean Water Act and the NPDES Program 1-5September 2010 NPDES Permit Writers’ Manual

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, municipa l, 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 (BOD 5 , TSS, fecal coliform, pH, and oil and grease).

 Toxic (priority) pollutants are those defined in CWA section 307(a)(1) (and listed in § 401.15 and Appendix A of Part 423) and include 126 metals and manmade organic compounds (see Exhibit C-1 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 pa rameters 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 p ast, 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 we tlands 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 th an 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 NPD ES 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 lowe r court cases. The court cases often have been difficult to interpret, resulting in much litigation an d an evolving understanding of the exact scope of waters subject to CWA jurisdiction. Also, permit wr iters should keep in mind that discharges through non-jurisdictional features that reach waters of the Un ited 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 Web site

< www.epa.gov/wetlands/guida nce/CWAwaters.html >.



### 1.3.4 Point Source 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 wh ich 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 st orm sewer system, and discharges from concentrated animal feeding operations (CAFOs), among others (see Exhibit 1-2). Return flows from irrigated agriculture and agricultural stormwater runoff specifi cally 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 contro ls 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

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Chapter 2: Regulatory Framework and Program Areas of the NPDES Program 2-1 

## CHAPTER 2. Regulatory Framework and Program Areas of the NPDES Program

This chapter discusses the regulatory framework of th e 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 govern ments, 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 Wate r Act (CWA) section 402, required the U.S. Environmental Protection Agency (EPA) to develo p 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 deve loped by EPA to implement and administer the NPDES program primarily are in Title 40 of the Code of Federal Regulations (CFR) Part 122

< www.epa.gov/lawsregs/search/40cfr.html >.
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 th e 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 cont ains federal agency regulations; proposed rules and notices; and executive orders, proclamations and ot her presidential documents. The National Archives and Records Administration, an independent federal ag ency responsible for managing all federal records, publishes the FR and CFR. The text of all final re gulations is found in the CFR. The background and implementation information related to these regula tions, however, are found in the preamble to the regulations contained in the FR. Th is 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 re lated to the NPDES program, and Exhibit 2-2 is an outline of the federal NPDES regulations from Part 122. The regulations at § 12 3.25 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.September 2010 NPDES Permit Writers’ Manual

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 e ffluent limitations guidelines and standards (effluent guidelines) Part 403 General pretre atment regulations Parts 405-471 Effluent guidelines Part 501 State sewage sludge ma nagement 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 a nd state governments in the administration of the NPDES program and the process by which a state can become authorized

.


### 2.2.1 State NPDES Program Authority EPA may authorize qualified state, territorial, or trib al 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 d ecision 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) Subpart 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 Subpart 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 Subpart 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 (k) Best management practices (BMPs) (l) Anti-backsliding (m) Privately owned treatment works (n) Grants (o) Sewage sludge (p) Coast Guard (q) Navigation (r) Great Lakes (s) Qualifying programs

§ 122.45 Calculating limitations (a) Outfalls and discharge points (b) Production basis (c) Metals (d) Continuous discharges (e) Non-continuous discharges (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 § 122.46 Duration of permits § 122.47 Schedules of compliance § 122.48 Requirements for recording and reporting of monitoring results § 122.49 Consideration under federal law § 122.50 Disposal into wells, into publicly owned treatment works or by land application Subpart 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

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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 continu es 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 permi tting authority in lieu of EPA. All new permit applications would then be submitted to the stat e 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 progra m 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 < www.epa.gov/npdes/authorization > provides the current authorization status for the states.



### 2.2.2 Roles and Responsibilities of the Federal and Stat e Authorities Until a state program is authorized, EPA is the perm itting authority that issu es all permits, conducts all compliance and monitoring activities, and enforces all program requirements.
As noted above, if a state has only partial authorit y, 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 Regi on is responsible for including conditions to implement the Part 503 Standards for the Use or Di sposal 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 pro cess 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 States 1

< www.epa.gov/npdes/pubs/owm0444.pdf >.
Once a state is authorized to issue permits, EPA gene rally 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 fede ral agencies (including EP A) with legal authority to implement and enforce the permit. Private citizens ma y also bring a civil action in federal court against an alleged violator or against the EPA Administ rator 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 st ate/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 stat es (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-municipa l facilities. Federal facilities fall in to the broader category of nonmunicipal facilities. Within those broad categories, ther e 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 muni cipal and non-municipal sources; identifies the NPDES program areas that address these activities; and iden tifies the applicable regulations for each NPDES
program area.



### 2.3.1 NPDES Program Areas Applicab le to Municipal Source s 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 th at 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 perm its is provided in the following sections.



### 2.3.1.1 Publicly Owned Treatment Works (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 define d 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 al so means the municipality that has the jurisdiction over the indirect discharges to and the discharges fro m the treatment works. Federally owned treatment works, privately owned treatment works, and other tr eatment plants not owned by a state or municipality are not considered POTWs.

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Exhibit 2-4 NPDES program areas and applicable regulations

Source Program areas Applicable regulations (40 CFR)

Municipal (POTWs) effluent discharges Part 122 Part 125 Part 133

Indirect non-municipal discharges (Pretreatment) Part 122 Part 403 Parts 405-471

Biosolids (sewage sludge) use and disposal Part 122 Part 257 Part 501 Part 503 Combined sewer overflow (CSO) discharges Part 122 Part 125 Sanitary sewer overflow (SSO) discharges Part 122 Municipal

Municipal separate storm sewe r systems (MS4s) discharges Part 122 Part 125

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 451Nonmunicipal (Industrial)

Vessel Discharges Part 122 * Though stormwater discharges from constructi on activity resulting in disturbance of 5 or more acres of total land area techni cally are considered, “stormwater discharges asso ciated with industrial activity” as defined by §122.26(b)(14)(x), these discharges a re 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 indus trial 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 t oxic 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 National Pretreatment Program

The National Pretreatment Program < www.epa.gov/npdes/pretreatment > regulates the introduction of nondomestic (i.e., industrial and commercial) wastewater to POTWs. B ecause 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 co mmercial 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. Th e federal program also requires certain indirect dischargers to meet technology-based requirements de veloped 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 c onditions 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 pretre atment 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

< www.epa.gov/OW-OWM.html/mt b/biosolids/index.htm >. The program regulates the use and disposal of sewage sludge by POTWs and by other TWTDS. TWTDS incl ude 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 ar e 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 sta ndards 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 Rule 2

< www.epa.gov/owm/mtb/biosolids/503pe/ >. 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 in dustrial 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 < www.epa.gov/npdes/cso/csodem >. 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 precipitati on, the systems can become overloaded. When that overloading occurs, the CSS can overflow at desi gned 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) < www.epa.gov/npdes/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 resu lted in progress toward controlling CSOs, significant public health and water quality risks remain. To expe dite compliance with the CWA, and to elaborate on the 1989 strategy, EPA, after collaboration with othe r CSO stakeholders (communities with CSSs, state water quality authorities, and envi ronmental groups), published the CSO Control Policy

< www.epa.gov/npdes/cso/controlpolicy > (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 co mprehensive and coordinate d planning effort to achieve cost-effective CSO controls that ultimately m eet appropriate health and environmental objectives. The Wet Weather Water Quality Act of 2000 stipulat es 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. Secti on 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; howev er, 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) < www.epa.gov/npdes/sso >.
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 r ecreation. A description of the extent of human health and environmental impacts caused by releases of unt reated sewage, along with other information, is provided in the Report to Congress on the Impacts and Control of CSOs and SSOs 3

< www.epa.gov/npdes/csossoreport2004 >. That 2004 report shows that NP DES 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 < www.epa.gov/npdes/pubs/sso_f act_sheet_model_permit_cond.pdf > and draft model permit conditions < www.epa.gov/npdes/pubs/sso_m odel_permit_conditions.pdf > 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 conditi ons 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 significan t source of pollutants discharged to waters of the United States. While rainfall and snow are natural even ts, the nature of stormwater 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 ar eas 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 requireme nts 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 th e stormwater program to include small MS4s and construction activity disturbing between 1–5 acres.
The MS4 stormwater application regulations (Ph ase 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 appropr iate controls for such discharges to MS4s (55 FR 47990, November 16, 1990). Part II of the applicati on 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 app lications and are issued individual permits.
Phase II of the stormwater program extended the NPD ES permitting program to small MS4s in urbanized areas (64 FR 68722, December 8, 1999). The Phase II MS 4 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 re gulated 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 muni cipal 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 municipalit y 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, ope ration 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 applicati on 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 Regulatio ns Regarding

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Notices of Intent & NPDES General Permitting for Phase II MS4s 4

< www.epa.gov/npdes/pubs/hanl onphase2apr14signed.pdf >.

In addition to information on the Stormwater Discharges From Municipal Separate Storm Sewer Systems (MS4s) Website < www.epa.gov/npdes/stor mwater/municipal >, 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 Systems 5 < www.epa.gov/npdes/pubs/owm0246.pdf >.

 Interim Permitting Approach for Water Quality -Based Effluent Limitations in Stormwater Permits 6 < www.epa.gov/npdes/pubs/swpol.pdf >.

 Establishing Total Maximum Daily Load (TMDL) Wasteload Allocations (WLAs) for Storm Water Sources and NPDES Permit Requirements Based on Those WLAs 7

< www.epa.gov/npdes/pubs/final-wwtmdl.pdf >.

 MS4 Program Evaluation Guidance 8 < www.epa.gov/npdes/pubs/ms4guide_withappendixa.pdf >.

 MS4 Permit Improvement Guide 9 < www.epa.gov/npdes/pubs/ms4permit_improvement_guide.pdf >.
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 commercia l facilities, industrial stormwater (including large construction activities), and discharges from small cons truction activity, concentrated animal feeding operations (CAFOs) and concentrated aquatic an imal production (CAAP) facilities. Unlike municipal sources, the types of raw materials, production pr ocesses, 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, genera lly are carried out within a more clearly defined area; thus, the collection systems are less complex than POTW collection systems. In addition, unlikebiosolids at POTWs, the NPDES program does not regulate residuals (sludge) generated by nonmunicipal facilities.
Non-municipal facilities can have discharges of stormw ater 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 wate r. 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 prod uct, byproduct, or waste product.”

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Process wastewater can contain pollutants at levels th at could affect the quality of receiving waters. The NPDES permit program establishes specific requireme nts 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 cove red 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 standard s (see section 5.2 of this manual). The stormwater that runs off the property of an industrial or commerc ial facility or from a cons truction site might require an NPDES permit under the industrial stormwat er 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 wastewat er, 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-pr ocess wastewater dilutes the concentration of pollutants of concern in process wastewater. The perm it 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 stormw ater discharges from industrial fac ilities, the NPDES program includes an industrial stormwater permitting component. Operator s 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 wate rs of the United States require authorization under an NPDES industrial stormwater permit. EPA publis hed 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 associat ed 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 industr ial 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 guidelin es, 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, c oncrete, 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 yard s, battery reclaimers, salvage yards, and automotive junkyards.

 Steam electric power generating facilities, including coal-handling sites.

 Transportation facilities that have vehicle mainte nance shops, equipment cleaning operations, or airport deicing operations.

 Major POTW sludge handling facilities, includi ng 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, stat e- or municipally owned or operated that meet the above descriptions must also submit applications.

EPA issued a final rule for Phase II of the stormwat er 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 c onditionally 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 < www.epa.gov/npdes/stormwater/noexposure >.
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 stormwat er-specific individual NPDES permit. Incorporating permit conditions to address stormwater discharges as sociated 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

< www.epa.gov/npdes/stormwater >.
Permit Conditions for Stormwater Discharges Associated with Industrial Activity All stormwater discharges associated with industrial activity that disch arge stormwater through a separate MS4 or discharge directly to waters of the Unite d 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 stormwat er 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 w as not well-defined or requi red 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 industri al 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 measur es, including BMPs, that control the discharge of stormwater associated with industrial activity.

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The EPA- and state-issued stormwater general perm its 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 nonstructu ral, 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 area s 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 polluta nts 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 impl emented to prevent or minimize pollution of stormwater, including the following:

− Good housekeeping or upkeep of industrial areas exposed to stormwater.

− Preventive maintenance of stormwater c ontrols 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 fo r developing appropriate special conditions for stormwater control measures are other stormwater ge neral permits. Using existi ng general permits as the basis for special conditions is en couraged because doing so will reduce duplication of effort. A listing of individual and general permits (sto rmwater and non-stormwater) issued by EPA and authorized states is on the View NPDES Individual a nd General Perm its Website < www.epa.gov/npdes/permitsearch >. In addition to the Stormwater Discharge From Industrial Facilities Website < www.epa.gov/npdes/stormwater/indust >, EPA published Developing Your Stormwater Pollution Prevention Plan: A Guide for Industrial Operators 10

< www.epa.gov/npdes/pubs/indu strial_swppp_guide.pdf > 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 stor mwater 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 c onstruction 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 pe rmit for stormwater discharges), though states have the option of not requiring the submittal of NOIs for stormwater discharges as sociated with small construction activity.

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EPA and NPDES-authorized state permitting authoriti es may include permit conditions that incorporate qualifying state or local erosion and sediment contro l 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 a nd 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 dup licative or conflicting erosion and sediment control requirements between the local program requirements and the NP DES general permit control requirements addressing stormwater discharges associated with construction ac tivity. 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 a ll other permit conditions.
The permit requirements in a construc tion 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 < www.epa.gov/npdes/stormwater/construction >, EPA also developed the Stormwater Pollution Prevention Plans for Construction Activities Website

< www.epa.gov/npdes/swpppguide >. 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 est ablished pursuant to CWA sections 301 or 306 and applicable to a point source will require that the lo cation, 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 in to waters of the United States. EPA has established national performance standards under CWA section 316( b) designed to reduce the impingement and entrainment of fish and other aquatic organisms as th ey are drawn into a facility’s cooling water intake structure(s). Impingement occurs when organisms ar e 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 regulatio ns at Part 402 to address cooli ng water intake structures. Fiftyeight 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 wit hdrew 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 complete d 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 wa s completed in July 2004 (Part 125, Subpart J).

2-14 Chapter 2: Regulatory Framework and Program Areas of the NPDES ProgramSeptember 2010 NPDES Permit Writers’ Manual

 Phase III addressed other existing facilities, includi ng 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, est ablish national standards only for new offshore and coastal oil and gas extraction facilities (Part 125, Su bpart N). EPA decided that other Phase III industrial facilities withdrawing water for cooling purposes woul d not be covered by natio nal standards but would continue to be subject to CWA section 316(b) requi rements 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 cha llenges. While the Phase I rule was largely upheld, the court reviewing the Phase II regulation rejected a nu mber of its provisions. Under remands from the reviewing courts, EPA is reevaluating the Phase II re gulation 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

< www.epa.gov/waterscience/316b/ >, 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 fac ility (other than an aquatic animal production facility) where the following conditions are met:

 Animals have been, are, or will be stabled or confin ed and fed or maintained for a total of 45 days or more in any 12-month period.

 Crops, vegetation, forage growth, or post-har vest 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 CA FO, or that are designated as CAFOs by the permitting authority, and that discharge or propose to disch arge are required to be permitted under the NPDES permitting program.
An animal operation must meet the definition of an AFO [§ 122.23(b)(1)] 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 prop ose to discharge are subject to NPDES permitting requirements.
CAFOs are subject to requirements that limit di scharges 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 s ubstantive 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 < www.epa.gov/npdes/cafo >. In addition, section 4.3.4 of this manual discusses application requirements for CAFOs.



### 2.3.2.6 Concentrated Aquatic Anim al Production (CAAP) Facilities CAAP facilities also are regulated under the NPD ES 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 annua l production equal to or greater than 100,000 pounds of aquatic animals. Th e rule requires a BMP plan and implementation of measures, including recordkeeping and reporting requ irements, to minimize discharges of solids, to prevent spills of drugs, feed, and chemicals that coul d 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 desi gnated as a CAAP facility under the designation authority in § 122.24(c). For more information, see the Aquatic Animal Production Industry Effluent Guidelines Website < www.epa.gov/guide/aquaculture/ >.



### 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 permit ting exceeded the Agency’s authority under the CWA. On September 18, 2006, the Court issued an or der 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 re gulate 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 dischar ges under a newly created CWA section 312(o). As a result of the law, EPA did not finalize the previously proposed Recreational Ves sel General Permit and is instead undertaking rulemaking to develop BMPs fo r 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 mo ratorium 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 th e expiration date of the moratorium from July 31, 2010, to December 18, 2013.

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Chapter 2: Regulatory Framework and Program Areas of the NPDES Program 2-17 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 domestical ly 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 < www.epa.gov/npdes/vessels >.



## 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 List 11

< www.epa.gov/npdes/pubs/owm0364.pdf > and Delegation of Updates to Major/Minor Lists 12

< www.epa.gov/npdes/pubs/owm0142.pdf>, EPA has established working definitions for POTW and nonmunicipal 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 < www.epa.gov/npdes/pubs/owm0116.pdf >. 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 remain ed 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 < www.epa.gov/npdes/ > frequently.September 2010 NPDES Permit Writers’ Manual

2-18 Chapter 2: Regulatory Framework and Program Areas of the NPDES Program 1 Prothro, M. 1983. EPA’s Authority to Issue NPDES Genera l Permits in Approved NPDES States. U.S. Environmental Protection Agency, Office of Water. Memorandum, July 11, 1983. < www.epa.gov/npdes/pubs/owm0444.pdf >.

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.

< www.epa.gov/owm/mtb/biosolids/503pe/ >.

3 U.S. Environmental Protection Agency. 2004. Report to Congress on the Impacts and Control of CSOs and SSOs. EPA 833-R04-001. U.S. Environmental Protection Agen cy, Office of Water, Washington, DC. < www.epa.gov/npdes/csossoreport2004 >.

4 Hanlon, J.A. 2004. Implementing the Partial Remand of the Stormwater Phase II Regulati ons Regarding Notices of Intent & NPDES General Permitting for Phase II MS4s . U.S. Environmental Protection Agency , Office of Wastewater Management. Memorandum, April 16, 2004. < www.epa.gov/npdes/pubs/han lonphase2apr14signed.pdf >.

5 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 Wate r, Washington, DC. < www.epa.gov/npdes/pubs/owm0246.pdf >.

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. < www.epa.gov/npdes/pubs/swpol.pdf >.

7 Wayland, R.H., III, and J.A. Hanlon. 2002. Establishing Total Maximum Daily Load (TMDL) Wasteload Allocations (WLAs) for Storm Water Sources and NPDES Permit Requirements Ba sed on Those WLAs. U.S. Environmenta l Protection Agency, Office of Wetlands, Oceans and Watersheds and Office of Wastewater Manage ment. Memorandum, November 22, 2002.

< www.epa.gov/npdes/pubs/final-wwtmdl.pdf >.

8 U.S. Environmental Protection Agency. 2007. MS4 Program Evaluation Guidance. EPA-833-R-07-003. U.S. Environmental Protection Agency, Office of Waste water Management. Washington, DC.

< www.epa.gov/npdes/pubs/ms4 guide_withappendixa.pdf >.

9 U.S. Environmental Protection Agency. 2010. MS4 Permit Improvement Guide . EPA833-R-10-001. U.S. Environmental Protection Agency. Office of Water, Washington, DC. < www.epa.gov/npdes/pubs/ms4permit_improvement_guide.pdf >

10 U.S. Environmental Protection Agency. 2009. Developing Your Stormwater Pollution Prevention Plan: A Guide for Industrial Operators . EPA 833-B-09-002. U.S. Environmental Protection Agency, Office of Wa ter, Washington, DC.

< www.epa.gov/npdes/pubs/indu strial_swppp_guide.pdf >.

11 Dougherty, Cynthia. 1988. Procedures for Revising the Major Permit List. U.S. Environmental Pr otection Agency, Permits Division. Memorandum, December 28, 1988. < www.epa.gov/npdes/pubs/owm0364.pdf >.

12 Pendergast, James F. 1995. Delegation of Updates to Major/Minor Lists. U.S. Environmental Protection Agency, Office of Wastewater Management. Memo randum, February 6, 1995. < www.epa.gov/npdes/pubs/owm0142.pdf >.September 2010 NPDES Permit Writers’ Manual

Chapter 3: Overview of the NPDES Permitting Process 3-1 

## 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 com ponents, and the permit development and issuance process. The permit process is illustrated by flow char ts. 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 individua l 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 tailo red 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 so urces (e.g., previous permit requirements, discharge monitoring reports, technology and water quality standa rds, 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 requireme nt to reapply before the expiration date.



### 3.1.2 General Permits A permitting authority develops and issues a genera l 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 othe r 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 wher e 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)(1) provide for gene ral permits to cover dischargers within an area corresponding to specific geographic or po litical boundaries such as the following:

 Designated planning area.

 Sewer district.

 City, county, or state boundary.September 2010 NPDES Permit Writers’ Manual

 State highway system.

 Standard metropolitan statistical area.

 Urbanized area.
The regulation also allows a genera l 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 ma nner 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 locati ons 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 lim itations on the basis of applicab le 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 nu meric effluent limitations. Examples include additional monitoring activities, special studies, best management practices (BMPs), and compliance schedules.

 Standard Conditions: Pre-established conditions that appl y 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 documenta tion and the required elements of a fact sheet or statement of basis.
Although the major sections of a perm it listed above are part of all perm its, 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 show s 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 diffe rent permitting authorities to use different names for each section of a permit.

3-2 Chapter 3: Overview of the NPDES Permitting ProcessSeptember 2010 NPDES Permit Writers’ Manual

Exhibit 3-1 Permit components



## 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 condition s and issue each permit generally follows a common set of steps. Exhibit 3-2 illustrates the major step s to develop and issue NP DES 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 permitti ng process generally begins when a facility operator submits an application. After receiving the application and maki ng 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 inform ation 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 pro cess is deriving technology-based effluent limitations (TBELs). Following that step, the permit writer deriv es 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 lim itations 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

Chapter 3: Overview of the NPDES Permitting Process 3-3September 2010 NPDES Permit Writers’ Manual

biochemical oxygen demand (BOD 5 ) that have different bases, such as an average monthly limitation based on effluent guidelines and a maximum daily limitation based on wate r quality standards.

Exhibit 3-2 Major steps to develop a nd issue NPDES individual permits

3-4 Chapter 3: Overview of the NPDES Permitting ProcessSeptember 2010 NPDES Permit Writers’ Manual

After effluent limitation development, the permit wr iter 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 pub lic participation in the permit process and EPA review of the permit or, in the case of an EPA-issued perm it, certification under CWA section 401 by the state with jurisdiction over the receiving water that the pe rmit 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, th e permitting authority then produces a final permit, with careful attention to documenting the process an d 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 genera l permits is similar to the process for individual permits; however, there are some differences in the se quence 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

Chapter 3: Overview of the NPDES Permitting Process 3-5September 2010 NPDES Permit Writers’ Manual

3-6 Chapter 3: Overview of the NPDES Permitting Process For general permits, the permitting authority first identif ies 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 sa me as for individual permits. The permitting authority develops a draft permit that includes effluent lim itations, 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 certifica tion 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 th at wishes to be covered under the general permit.
After the final general permit has been issued, faciliti es 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, notif y 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 i ssue an individual permit, but much of the technical discussion applies equally to general permit development.September 2010 NPDES Permit Writers’ Manual

Chapter 4: NPDES Permit Application Process 4-1 

## 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 revi ewing the application and evaluating background information about the applicant. Through this pr ocess the permit writer gains an understanding of the circumstances of the discharge and the characteristi cs 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 § 12 2.28, who discharges pollutants or proposes to discharge pollutants to waters of the United Stat es 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 regula tion 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 ow ner (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 dischar ges or proposed discharges to waters of the United States; however, NPDES permits are not requi red for some activities as specified under the Exclusions provision in § 122.3. Exceptions include the following:

 Discharge of dredged or fill materials into wa ters 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 Haza rdous Substances Pollution Contingency Plan) or 33 CFR 153.10(e) (Pollution by Oil and Hazardous Substances).

 Any introduction of pollutants from nonpoint sour ce agricultural and silvicultural activities, including stormwater runoff from orchards, cultiv ated crops, pastures, range lands, and forest lands, but not discharges from concentrated anim al 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.September 2010 NPDES Permit Writers’ Manual

 Discharges into a privately owned treatment work s, except as the Director may otherwise require under § 122.44(m).
While those types of discharges have been ex cluded from permitting requirements under the NPDES program, they might be subject to controls unde r other federal or state regulatory programs.
As of the date of this manual’s publication, the excl usion 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 In secticide, 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 p esticides 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 w ill 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 Apr il 9, 2011, respectively. The effect of the vacaturs on the exclusions in § 122.3 is presented in Exhibit 4-1.

Exhibit 4-1 Effect of court decisions on § 122.3
Exclusion 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 t he 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 vess el is operating in a capacity other than as a means of transportation) do not constitute the, “discharge of a pollutant” when such discharges occur bey ond 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 vesse l 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 t hat 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 le ft. On June 8, 2009, the court granted a request from the U.S. D epartment 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 fo r the discharge of pollutants from the application of pesticides. Before Apri l 9, 2011, permits are not required for discharges from these applications w hen applied in accordance with the product’s FIFRA label. Certain related activities continue to be exempt from permitting under the CWA (i.e., irrigat ion return flow and agricultural stormwater runoff).

4-2 Chapter 4: NPDES Permit Application ProcessSeptember 2010 NPDES Permit Writers’ Manual



## 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.

Exhibit 4-2 When to apply for an NPDES permit Type of permit Type of discharge Schedule*

New At least 180 days before the date on which the discharge is to commence Existing At least 180 days before expiration date of existing permit Individual

Construction Stormwater At least 90 days before the date on which construction is to commence New Specified in general permit General Existing X number of days following issuance of permit (specified in the general permit) * Authorized states may use more stringent deadlines.

Anyone proposing a new discharge must apply to the permitting authority no later than 180 days before the expected commencement of the discharge if appl ying 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 indivi dual 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 al so 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 Regiona l 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 accordan ce 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 e xpired 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 mu st 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 submitte d, and references the co rresponding NPDES regulatory citation. In some cases, a facility might need to f ile more than one application form. For example, an

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existing industrial facility (i.e., renewal) dischargi ng 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 app lication requirements presented below.

Exhibit 4-3 EPA application require ments 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) New and existing Form 2A , Parts A, B and C; Parts D, E, F, or G as applicable  § 122.21(a)(2)(i)(B)

 § 122.21(j)

 POTWs with design flows less than 0.1 mgd New and existing Form 2A , Parts A and C; Parts D, E, F, or G as applicable  § 122.21(a)(2)(i)(B)

 § 122.21(j)

TWTDS (sewage sludge) New and existing Form 2S  § 122.21(a)(2)(i)(H)

 § 122.21(q) Concentrated animal production facilities

 Concentrated animal feeding operations

 Concentrated aquatic animal production facilities New and existing Form 1 and Form 2B  § 122.21(a)(2)(i)(A) and (C)

 § 122.21(f) and (i)

Existing Form 1 and Form 2C  § 122.21(a)(2)(i)(A) and (D)

 § 122.21(f) and (g)
New (process wastewater) Form 1 and Form 2D  § 122.21(a)(2)(i)(A) and (E)

 § 122.21(f) and (k) Industrial facilities

 Manufacturing facilities

 Commercial facilities

 Mining activities

 Silvicultural activities New and existing (non-process wastewater) Form 1 and Form 2E  § 122.21(a)(2)(i)(A) and (F)

 § 122.21(f) and (h)
Stormwater discharges associated with industrial activities (except stormwater discharges associated with construction activity) New and existing Form 1 and Form 2F  § 122.21(a)(2)(i)(A) and (G)

 § 122.21(f)

 § 122.26(c)

Stormwater discharges associated with construction activity New and existing Form 1  § 122.21(a)(2)(i)(A)

 § 122.21(f)

 § 122.26(c)(1)(ii) Stormwater discharges from MS4s serving a population greater than 100,000 New and existing None  § 122.26(d)

Stormwater discharges from small MS4s New and existing None  § 122.33

 § 122.21(f) Cooling water intake structures New and existing None  § 122.21(r)

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### 4.3.1 Form 1: General Information All facilities applying for an individual NPDES perm it, 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 < www.epa.gov/npdes/pubs/form_1.pdf >. The type of general facility information required by Form 1 is specifi ed in §§ 122.21(a)(2)(i)(A) and 122.21(f) and includes the following:

 Name, mailing address, facility c ontact, 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 < www.epa.gov/npdes/pubs/final2a.pdf >. EPA issued a final rule amending permit application requirements a nd application forms for POTWs and other TWTDS (64 FR 42433, August 4, 1999). The rule consolidat ed 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 wa ters 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 inf iltration 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 Applicati on Information (Parts D–G). POTWs complete these additional forms, as applicable, depending on th e characteristics of the municipal discharge:

 Part D requests expanded effluent testing data for metals, volatile organic compounds, acidextractable 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 au thority 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 Pr etreatment Standards under § 403.6 and 40 CFR Chapter I, Subchapter N.

− 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 dryweather hydraulic or organic capacity of the treatment plant.

o Is designated an SIU by the control aut hority 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 h as consistently complied with all applicable categorical pretreatment standards and requirements.

o The industrial user annually submits a certif ication statement required in § 403.12(q) and any information necessary to support the certification statement.

o The industrial user never discharges an y 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 require ment, 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) even ts, receiving waters, and operations.



### 4.3.3 Form 2S: New and Existing TWTDS New TWTDS and TWTDS with effective NPDES pe rmits must submit a new or renewal permit application, respectively, using new Form 2S < www.epa.gov/npdes/pubs/final2s.pdf >. 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 2B: New and Existing Con centrated Animal Feeding Operations (CAFOs) and Concentr ated 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 < www.epa.gov/ne/npdes/2010RevisedCafoFedRegstrForm2b.pdf >. Form 2B was significantly m odified as part of the final CAFO Ru les (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 th e 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 < www.epa.gov/npdes/cafo >.

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Sections 2.3.2.5 and 2. 3.2.6 of this manual pr ovide additional informa tion 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 < www.epa.gov/npdes/pubs/3510-2C.pdf >. 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 conven tional, 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 indus trial dischargers vary de pending on the industrial category of the facility, the facility’s discharge charact eristics and the types of pollutants expected to be present in the discharge.



### 4.3.6 Form 2D: New Manufacturing, Commer cial, 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 < www.epa.gov/npdes/pubs/3510-2D.pdf >. New dischargers are those that have not previously obtained permits fo r 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, Commercia l, Mining, and Silvicultural Facilities that Discharge On ly Non-Proces s Wastewater In addition to Form 1, operators applying fo r 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 < www.epa.gov/npdes/pubs/3510-2E.pdf >. Non-process
wastewater includes sanitary wastes, restaurant or cafeteria wastes, and non-contact cooling water, but it does not include stormwater. Stormwater 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

< www.epa.gov/npdes/pubs/3510-2F.pdf>. Applicants whose discharge is composed of stormwater and nonstormwater 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 Activity 1 < www.epa.gov/npdes/pubs/owm0241.pdf > to assist operators of facilities that discharge stormwater associ ated 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 th e 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, includ ing a brief description of applicable state and local erosion and sediment control requirements.

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 Proposed measures to control pollutants in st ormwater 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 MS 4s 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 Nove mber 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 la rge 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:

 Part 1

− 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 identifica tion of 5 to 10 representative outfalls for stormwater sampling.

− Description of existing stormwater management practices.

− Descriptions of existing budget and resources ava ilable 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 exp ected reductions in pollutant loadings.

− Fiscal analysis, including necessary capital a nd 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 inte nded 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 appro ach for reapplication requirements for operators of

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MS4s (61 FR 41698, 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 en courages changes to monitoring program s to make them appropriate and useful to stormwater management decisions. With the policy, EPA seeks to improve municipal stormwater management efforts by allowing munici palities to target their resources for the greatest environmental benefit.



### 4.3.11 Stormwater Discharges from Small MS4s The application requirements for sma ll MS4s are addressed in § 122.33. Most states have issued general permits for small MS4s; however, regulated small MS 4s 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 contro l measures) or a program that varies from § 122.34. EPA anticipates that mo st MS4s will follow the § 122.34 requirements.
Regulated small MS4s seeking an individual permit a nd 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 u nder §§ 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 re quirements in §§ 122.26(d)(1) and (2) by March 10, 2003. Small MS4s are not required to submit the info rmation required by §§ 122.26(d)(1)(ii) and (d)(2) regarding their legal author ity, unless they intend for the permit writ er 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 mo dification 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)(1)(iii) and (iv) and (d)(2)(iii) do not apply and compliance with §§ 122.26 (d)(1)(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 percen t 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 fo r such facilities must be developed on a case-by-case basis.
Phase III of the CWA section 316(b) rule was finali zed on June 16, 2006, in 71 FR 35006. The Phase III rule (Part 125, Subpart N) implements CWA secti on 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 incl udes facilities with a design intake flow of greater than 2 mgd and that use at least 25 percen t 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). For the most current information on regulatory requirements, see the Cooling Water Intake Structure Program Website

< www.epa.gov/waterscience/316b/ >.



## 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 speci fied 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 ac tivities. 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 fo r 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 cove rage under a general permit must seek coverage by submitting an NOI. The information that must be pr ovided 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 constr uction sites and industrial facilities that need to apply for coverage under EPA’s C onstruction General Permit (CGP) or Multi-Sector General Permit (MSGP), respectively. EPA’s Electronic Stormwater Notice of Intent (eNOI) Website

< www.epa.gov/npdes/stormwater/enoi > presents additional information about eNOI.

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## 4.5 Application Review
The contents of individual NPDES permits are based , in part, on the information included in the application. Thus, the application must be comple te and accurate before a permit writer can properly develop a permit. Exhibit 4-4 depicts the general pr ocess for reviewing a permit application, based on a chart provided in the Washington Department of Ecology’s Permit Writers’ Manual 2

.
Exhibit 4-4 Permit application review process

After the initial application review, the permit wr iter may request that an applicant submit other inform ation needed to decide wh ether to issue a permit and for permit development. The requested information could include the following:

 Additional information, quantitativ e 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 corr espondence might be required before the permit writer obtains all the information that he or sh e 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 applica tion 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 corr ect 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 ha ndled by telephone and even minor items should be documented in writing in the permit file. Under no ci rcumstances should a permit writer edit or modify the application, which is a legal document that has b een signed and certified by the applicant. The original application, any subsequent clarif ications, and any supplemental inform ation 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 corr ections 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 opera ting data for a treatment system, to process the permit. According to § 122.21(e), an application is cons idered 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 a pplicant may submit additional information voluntarily or be required to do so under CWA section 3 08 or under a similar provision of state law.



### 4.5.2 Common Omissions in Applications

This section identifies some of the most comm on omissions and errors found in NPDES permit applications and provides examples of ways to iden tify 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 attach ment 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 th at 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 e ffluent 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 efflue nt 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 require ments for toxic pollutants (see § 122.21, Appendix D, Table I and Table II and al so listed in Application Form 2C).

 Production rates and flow data from industrial facilities that are subject to production- or flowbased 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 polluta nts 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, tota l 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 se ction 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 fracti on (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 inst ructions 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 manufactur ers. 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 c ontaminants could be present in a wastestream.

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Exhibit 4-5 Considerations for an app lication to be complete (continued)
Example 3: An integrated slaughterhouse and meat pr ocessing 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 developm ent 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, ev en 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 expect ed, 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 determinati on of pollutant data required in the application.

Exhibit 4-6 Example of required te sting 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 t he 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.



### 4.5.3 The Accurate Application All information submitted on a permit application mu st be accurate. Although it might be difficult to detect certain inaccuracies, a number of common mist akes can be readily detected. When mistakes are detected, they must be corrected. Generally, any corre ction 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 in advertent because of the length and complexity of the form. Note, however, that the application certifica tion statement indicates, “...that there are significant penalties for submitting false information, including th e possibility of fine and imprisonment for knowing violations.” If the permit writer believes that falsifi cation 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 appli cations include failing to provide the correct longterm average and daily maximum values, reporting qu antified values below known detection limits, and using misplaced decimal points or incorrect concen tration 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 Pollut ant Discharge Elimination System (NPDES) Permits 3

< www.epa.gov/npdes/pubs/mercury memo_analyticalmethods.pdf > describes when a method for mercury is sufficiently sensitive for purposes of permit applications a nd monitoring under a permit. In the memorandum, EPA strongly recommends that a permitti ng authority determine that a permit application that lacks effluent data analyzed with a sufficiently sens itive EPA-approved method (such as Method 1631E) is incomplete unless and until the facility supplements the original appl ication 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 perm it limitations and conditions.



### 4.6.1 Permit File Review Before developing the draft permit and fact sh eet, 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 plan t 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 < https://icis.epa.gov >.

 Online Tracking Information System (OTIS) < www.epa.gov/idea/otis/ >.

 Envirofacts Warehouse < www.epa.gov/enviro/ >.
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 compli ance 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) < www.epa.gov/STORET/ >.

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Exhibit 4-7 Considerations for an application to be accurate
Example 1: An industrial applicant provides a daily maximum effl uent flow value of 50,000 gpd in its permit application Form 2C. However, a review of historical water usage re cords 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 operat ions, or decreased its number of employees.
Question: Are reported values consistent with historical information?
Answer: No. An inspection of the facility revealed two separate wa ter meters (one for sanitary and one for process water); the applicant had overlooked the sanita ry meter. Further, the process water meter was found to be defective. Subsequent flow monitoring of the actual total wastes tream recorded a flow of 125,000 gpd. A new water meter was installed, and concurrent wastestream flow monitori ng 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 estimat ed 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 (lbs/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 lbs/day. Using the calculation below, the mass discharge that corresponds to the soli ds concentration (23 mg/L) and flow (1.2 mgd) would be 230 lbs/day: 23 mg/L x 1.2 mgd x 8.34 (lbs)(L)/ (mg)(millions of gallons) = 230 lbs/day (conversion factor) Because the applicant reported a maximum mass discharge of 690 lbs/day, a significant discrepancy is indicated. The permit writer should contact the applicant to resolv e 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 cyan ide are all reported as < 1,000 micrograms per liter ( μ g/L). When asked, the applicant indicate d 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 μ g/L. The applicant should be able to quantify results for total cyanide at values well below 1,000 μ g/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 woul d be of concern at effluent concentrations below 1,000 μ g/L, the permit writer should require the appl icant 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 effl uent guidelines and categorical pretreatment standards for a variety of industrial categories.

 Reference textbooks and technical documents th at provide information about manufacturing processes and wastestreams for specific industry cat egories, which are available from libraries such as

− National Technical Information Service (NTIS) < www.ntis.gov >.

− EPA libraries < www.epa.gov/natlibra/libraries.htm >.

− Office of Water Resource Center (OWRC) < www.epa.gov/safewater/resource/ >.

− National Service Center for Environmental Publications (NSCEP) < www.epa.gov/ncepihom/ >.

 Related environmental permits th at 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 Manual 4 , which is a five-volume guidance manual that provides detailed descriptions of industrial processes, potential po llutants from each process, appropriate treatment technologies, and cost estimating procedures.

 The Toxic Release Inventory (TRI) < www.epa.gov/tri/ >, which is accessible on EPA’s mainframe and through a public online service. The TRI contai ns information on more than 300 listed toxic chemicals released by specific facilities, including chemical identification, quantity of chemicals released to various environmental media, o ff-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 informati on 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, pretreatme nt 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, equi pment 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 runo ff, 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 mate rials, products, and by-products. The permit writer should review the water uses, the resulting wastewat er 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 r unoff 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 shoul d 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 prep aration. If necessary, the permit writer should meet with management to ask questions or clarify info rmation 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 desire d information from facility compliance inspections and should try to coordinate the timing of compliance in spections 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

< eros.usgs.gov/#/Find_Data >; TerraServer < www.terraserver.com >; Google Earth < earth.google.com >; and other private contractors.

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Chapter 4: NPDES Permit Application Process 4-21 

## 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 informa tion submitted with applications.

 Permits.

 Effluent data.
Information that may be claimed as confidential in cludes 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 Stormwater Discharges Associat ed With Industrial Activity. EPA-505/8-91-002. U.S. Environmental Protection Agency, Office of Water, Washington DC, < www.epa.gov/npdes/pubs/owm0241.pdf >.

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. < www.ecy.wa.gov/pubs/92109.pdf >

3 Hanlon, James A. 2007. Analytical Methods for Mercury in National Po llutant Discharge Elimin ation System (NPDES) Permits. U.S. Environmental Protection Agency, Office of Wastewater Management. Memo randum, August 23, 2007.

< www.epa.gov/npdes/pubs/mercury memo_analyticalmethods.pdf >.

4 U.S. Environmental Protection Agency. 1980. Treatability Manual: Vol. I. Treatability Data (EPA-600/8-80-042a) publications available on NEPIS Website < www.epa.gov/nscep/ > as document 600880042A ; Vol. II. Industrial Descriptions (EPA-600/8-80- 042b) as document 600880024B ; Vol. III. Technologies (EPA-600/8-80-042c) as document 600880024C ; Vol. IV. Cost Estimating (EPA-600/8-80-042d) as document 600880042d; Vol. V. Summary (EPA-600/8-80-042e) as document 600880024E. U.S. Environmental Protection Ag ency, Office of Research and Development, Washington, DC.September 2010 NPDES Permit Writers’ Manual

Chapter 5: Technology-Based Effluent Limitations 5-1 

## CHAPTER 5. Technology-Based Effluent Limitations

One of the major strategies of the Clean Water Ac t (CWA) in making “reasonable further progress toward the national goal of eliminating the discharge of all pollutants” is to require e ffluent limitations based on the capabilities of the technologies available to cont rol those discharges. Technology-based effluent limitations (TBELs) aim to prevent pollution by requi ring 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 inde pendently of the potential impact of a discharge on the receiving water, which is addressed through water quality standards and wate r 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 treat ment 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 al so need to apply anti-back sliding 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 limitationsSeptember 2010 NPDES Permit Writers’ Manual



## 5.1 Technology-based Effluent Limitations for POTWs
The largest category of dischargers requiring in dividual 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 PO TW Treatment Plant,” as defined in § 403.3(r). Under § 403.3(q), the term POTW “also means the m unicipality 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 thr ough the application of secondary treatment. Under CWA section 301(b)(1)(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 “e quivalent to secondary treatment” standards.



### 5.1.1 Secondary and Equivalent to Secondary Treatment Standards Several regulations implement the statutory requ irements for developing standards and discharge limitations based on secondary treatment. EPA has promulgated regulations in Part 133 establishing secondary treatment standards, equivalent to seconda ry treatment standards, and a number of special considerations applied on a case-by-case basis. In a ddition, § 122.44(a)(1) requires that NPDES permits include applicable technology-based limitations and standards, while re gulations at § 125.3(a)(1) state that TBELs for POTWs must be based on secondary treatment standards (which includes the “equivalent to secondary treatment standard s”) specified in Part 133.



### 5.1.1.1 Secondary Treatment Standards In Part 133, EPA published secondary treatment standa rds based on an evaluation of performance data for POTWs practicing a combination of physical and biol ogical 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 (BOD 5 ), total suspended solids (TSS), and pH . Exhibit 5-2 summarizes the standards.

Exhibit 5-2 Secondary treatment standards
Parameter 30-day average 7-day average BOD 5 30 mg/L (or 25 mg/L CBOD 5 ) 45 mg/L (or 40 mg/L CBOD 5 ) TSS 30 mg/L 45 mg/L BOD 5 and TSS removal (concentration) not less than 85%

-- pH within the limits 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 fr om 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 sta ndards that apply to certain facilities employing waste stabilization ponds or trickling filters as the principa l process. Those standards are called equivalent to secondary treatment standards.



### 5.1.1.2 Equivalent to Secondary Treatment Some biological treatment technologies, such as trick ling filters or waste stabilization ponds, are capable of achieving significant reductions in BOD 5 and TSS but might not consis tently achieve the secondary treatment standards for these parameters. Congress recognized that unless alternate limitations were set for facilities with trickling filters or waste stabiliza tion ponds, which often are in small communities, such facilities could be required to cons truct 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 ac hieving their original design performance levels, Congress included provisions in the 1981 amendmen ts 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 applicati on 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
Parameter 30-day average 7-day average

BOD 5 not to exceed 45 mg/L (or not to exceed 40 mg/L CBOD 5 ) not to exceed 65 mg/L (or not to exceed 60 mg/L CBOD 5 ) TSS not to exceed 45 mg/L not to exceed 65 mg/L BOD 5 and TSS removal (concentration) not less than 65%

-- pH within the limits 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 fr om 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 e quivalent to secondary standards, a POTW must meet all three of the following criteria:

Criterion #1 —Consistently Exceeds Secondary Treatment Sta ndards: The first criterion that must be satisfied to qualify for the equivalent to seconda ry standards is demonstrating that the BOD 5 and TSS effluent concentrations consiste ntly achievable through proper operation and maintenance of the treatment works exceed the secondary treatment sta ndards 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

Chapter 5: Technology-Based Effluent Limitations 5-3September 2010 NPDES Permit Writers’ Manual

 (f)(1): For a given pollutant parameter, the 95 th 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 e rrors, or other unusual conditions.

 (f)(2): A 7-day average value equal to 1.5 tim es the value derived under paragraph (f)(1).
Some facilities might meet this criterion only for the BOD 5 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 (BOD 5 or TSS) if the effluent concentrati on of only one of the parameters is demonstrated to consistently exceed the secondary treatment standards.

Criterion #2 —Principal 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 #3 —Provides Significant Biological Treatment: The third criterion for applying equivalent to secondary standards is that the treatment wo rks 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 BOD 5 . 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 wr iter should assemble enough influent, effluent, and flow data from the facility to adequately characterize th e 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 Co mpliance Personnel—Secondary Treatment Redefinition 1 that a treatment works operating beyond its design hydraulic or organic loading limit is not eligible for application of equivalent to secondary st andards. If overloading or structural failure is causing poor performance, the solution to the problem is c onstruction, not effluent limitations adjustment.



### 5.1.2 Adjustments to Equivalent to Secondary Standards In addition to providing secondary tr eatment 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 stabi lization ponds upward from those specified in the equivalent to secondary treatment standards to conf orm 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 st abilization ponds that are achieving the levels of effluent quality for BOD 5 specified in § 133.105(a)(1) (45 millig rams 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 pr ocess 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.

Exhibit 5-4 State-specific adjusted TSS requirements*

Location Alternate TSS limitation (30-day average) (mg/L) Location Alternate TSS limitation (30-day average) (mg/L) Alabama 90 Nebraska 80 Alaska 70 North Carolina 90 Arizona 90 North Dakota Arkansas 90  North and east of Missouri R. 60 California 95  South and west of Missouri R. 100 Colorado Nevada 90

 Aerated ponds 75 New Hampshire 45

 All others 105 New Jersey None Connecticut None New Mexico 90 Delaware None New York 70 District of Columbia None Ohio 65 Florida None Oklahoma 90 Georgia 90 Oregon Guam None  East of Cascade Mountains 85 Hawaii None  West of Cascade Mountains 50 Idaho None Pennsylvania None Illinois 37 Puerto Rico None Indiana 70 Rhode Island 45 Iowa South Carolina 90

 Controlled discharge, 3 cell Case-by-case but not greater than 80 South Dakota 120

 All others 80 Tennessee 100 Kansas 80 Texas 90 Kentucky None Utah None Louisiana 90 Vermont 55 Maine 45 Virginia Maryland 90  East of Blue Ridge Mountains 60 Massachusetts None  West of Blue Ridge Mountains 78

Michigan: Controlled seasonal discharge  East slope counties: Loudoun, Fauquier, Rappahannock, Madison, Green, Albemarle, Nelson, Amherst, Bedford, Franklin, Patrick. Case-by-case application of 60/78 limits

 Summer 70 Virgin Islands None

 Winter 40 Washington 75 Minnesota 40 West Virginia 80 Mississippi None Wisconsin 80 Missouri 80 Wyoming 100 Montana 100 Trust Territories and N. Marianas None * (49 FR 37005, September 20, 1984)

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### 5.1.2.2 Alternative State Requirements (ASRs) To further address the potential variations in facility performance arising from geographic, climatic, or seasonal conditions in different states, the revised s econdary 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 BOD 5 and TSS for trickling filter facilities and for BOD 5 for waste stabilization pond facilities. ASRs are set at le vels 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 Applying Secondary Treatment Standa rds, Equivalent to Secondary Treatment Standards, and Adjusted Standard s 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 monitori ng conditions, see section 8.1 of this manual). This section presents a step-by-step procedure to estab lishing 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 seco ndary treatment standards or Step 3. Calculate effluent lim itations based on equivalent to secondary standards or Step 4. Calculate effluent limitat ions based on adjusted standards Step 5. Apply special consider ations for further adjustments Step 6. Document the application of secondary or equivalent to secondary treatment standards or adjusted standards and all special c onsiderations in the fact sheet



### 5.1.3.1 Step 1: Determine Whether Secondary Treatment Standards or Equivalent to Secondary Treatment Standards or Adjusted Standards Apply 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 adju stments 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 comb ination 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 treatme nt regulation (49 FR 37002, September 20, 1984) and in § 133.105(f)(2), EPA noted that when developi ng permits for new trickling filter and waste

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stabilization pond facilities, permitting authorities shoul d consider the ultimate design capability of the treatment process, geographical and climatic cond itions, and the performance capabilities of recently constructed facilities in similar situations.
After determining whether secondary treatment standard s or equivalent to secondary treatment standards apply to a facility or a discharge, the permit writer ap plies the appropriate standa rds to develop effluent limitations. Section 5.1.3.2 below (S tep 2) details development of e ffluent 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 limita tions for facilities where adjusted sta ndards apply. It is possible that a facility with multiple biological treatment processes could have limitations ba sed on a combination of the standards (see section 5.1.3.5 below [Step 5]); ther efore, those sections are presented as separate steps.



### 5.1.3.2 Step 2: Calculate Effluent Limita tions Based on Secondary Treatment Standards If the facility being permitted is subject to the sec ondary 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 NP DES 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 trea tment standards and the regulatory requirements in § 122.45(d)(2).

Exhibit 5-6 Effluent limitations calcula ted from secondary treatment standards
Parameter Average monthly limitation Average weekly limitation BOD 5 30 mg/L (or 25 mg/L CBOD 5 ) 45 mg/L (or 40 mg/L CBOD 5 ) TSS 30 mg/L 45 mg/L BOD 5 and TSS removal (concentration) not less than 85% N/A
pH Within the range of 6.0–9.0 standard units at all times (or expressed as instantaneous minimum and maximum limitations)* * unless the POTW demonstrates that: (1) inorganic chemicals are not added to the waste stream as part of the treatment process; and (2) contributions fr om 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. Theref ore, EPA recommends that permit writers apply the 30-day and 7-day average secondary treatment standard s directly as average monthly (calendar month) and average weekly (calendar week) discharge limitations.
Second, § 122.45(f)(1) requires that all permit limita tions, 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 e xpressed 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 BOD 5 and TSS, including percent removal, are expressed in terms of concentration, the second condi tion 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 limita tions in a permit. In general, regulations at § 122.45(b)(1) 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 [lbs/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 Concentration-b ased limitation Conversion factor in million gallons per day in millig rams per liter 8.34 with units of (mgd) x (mg/L) x (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* = POTW design flow x Concentration-based limitation x Conversion factor

BOD 5 Average monthly = 2.0 mgd x 30 mg/L x 8. 34 (lbs)(L) / (mg)(millions of gallons) = 500 lbs/day Average weekly = 2.0 mgd x 45 mg/L x 8.34 (lbs)(L) / (mg)(millions of gallons) = 750 lbs/day

TSS Average monthly = 2.0 mgd x 30mg/L x 8.34 (lbs)(L) / (mg)(millions of gallons) = 500 lbs/day Average weekly = 2.0 mgd x 45mg/L x 8.34 (lbs)(L) / (mg)(millions of gallons) = 750 lbs/day
* calculated to 2 significant figures



### 5.1.3.3 Step 3: Calculate Effluent Limitations Based on Equivalent to Secondary 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 BOD 5 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 BOD 5 and TSS concentrations are achieva ble 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 abov e, the regulations at § 133.101(f) define, “effluent concentrations consistently achie vable through proper operation and ma intenance” 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, ope rational 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 th e 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 pe rmit after reviewing the additional data collected by the discharger.
As with limitations based on secondary treatment st andards (shown in Exhibit 5-6 above), limitations based on equivalent to secondary standards are e xpressed 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, th e federal regulations at § 133.103(c) allow states to adjust the maximum allowable discharge concentrat ion 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 th at modify equivalent to secondary requirements for both BOD 5 and TSS for trickling filter facilities and BOD 5 requirements for waste stabilization pond facilities. Where one or more of the adjusted standa rds 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 stat e has developed an adjusted TSS standard for waste stabilization ponds consistent with § 133.103(c), the re gulations would allow uniform application of that standard to POTWs where waste stabilization pon ds are the principal process used for secondary treatment and operation and maintenance data indi cate 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 massbased limitations may be calculated using the procedures outlined above.

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### 5.1.3.5 Step 5: Apply Special Consi derations for Further Adjustments Part 133 allows a permit writer to make further adju stments when calculating effluent limitations derived from secondary treatment standards or equivalent to secondary standards based on several special considerations. The permit writer shoul d 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 CBOD 5 for BOD 5 Wastewater contains carbonaceous oxygen dema nding substances and nitrogenous oxygen demanding substances. A CBOD 5 test measures the 5-day carbonaceous bi ochemical oxygen demand while the BOD 5 test measures the both carbonaceous biochemical ox ygen demand and nitrogen ous biochemical oxygen demand. During nitrification, nitrifying bacteria use a large amount of oxyge n to consume nitrogenous oxygen demanding substances (unoxi dized nitrogen and ammonia-nitrogen) and convert these to oxidized nitrate. For wastewaters with significant nitrogen content, basing permit limitations on CBOD 5 instead of BOD 5 eliminates the impact of nitrification on dischar ge limitations and compliance determinations. EPA recognizes that the CBOD 5 test can provide accurate information on treatment plant performance in many cases and, in Part 133, allows permit writers to use CBOD 5 limitations in place of BOD 5 limitations to minimize false indications of poor facility perform ance as a result of nitrogenous oxygen demand.

EPA has established CBOD 5 standards for cases where secondary treat ment standards or equivalent to secondary treatment standards are applied:

 Secondary Treatment: The CBOD 5 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 CBOD 5 (nitrogen inhibited) test procedure. Subject to any state-specific requi rements, a permit writer can specify these CBOD 5 limitations along with CBOD 5 monitoring requirements in any POTW permit requiring performance based on secondary treatment standards [§ 133.102(a)(4)].

 Equivalent to Secondary Treatment: The CBOD 5 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 CBOD 5 limitations, and subject to any state-specific requirements, a permit writer may substitute CBOD 5 for BOD 5 and specify CBOD 5 limitations and monitoring requirements when applyi ng equivalent to secondary standards.

Substitution of COD or TOC for BOD 5 Chemical oxygen demand (COD) and total organic car bon (TOC) laboratory tests can provide an accurate measure of the organic content of wastewater in a shorter time frame than a BOD 5 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 BOD 5 if a long-term BOD 5 :COD or BOD 5 :TOC correlation has been demonstrated.

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Adjustments for Industrial Contributions Under § 133.103(b), treatment works receiving wastes fro m industrial categories with effluent limitations guidelines and standards (effluent guidelines) requi rements or new source performance standards for BOD 5 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 BOD 5 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 BOD 5 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 BOD 5 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 quan tities 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 generall y 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 BOD 5 and TSS percent removal. The specific circumstances and the potential adjustments to the percent removal requirement are as follows:

 Treatment works that receive less concentr ated 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, l ess stringent percent removal requirements or a mass loading limitation instead of a percent re moval 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 duri ng 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 m eet, 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 rem oval limitations because of less concentrated influent.

2. To meet the percent removal requirements, th e facility would have to achieve significantly more stringent effluent concentrations than w ould otherwise be required by the concentrationbased 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 ot herwise 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 ex cessive infiltration is discussed in regulations at § 35.2005(b)(28). This regul ation 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 economica lly and effectively eliminated from a sewer system as determined in a cost-effectiveness an alysis. 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 c oncentrated influent wastewater is the result of clear water industrial discharges, then the tr eatment 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 re quirement or receive a mass loading limitation instead of the percent removal requirement provid ed the treatment plant demonstrates all of the following [§ 133.103(d)]:

1. The facility is consistently meeting or will cons istently m eet its permit effluent concentration limitations but cannot meet its percent rem oval 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, th e facility would have to achieve significantly more stringent limitations than would otherw ise 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 determin ation 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 additiona l criterion that flow is nonexcessive if the total flow to the POTW (i.e., wastewater plus inflow plus inf iltration) is less than 275 gallons per capita per day. The regulation at § 35.2005(b)(16) defines excessive I/I as the quan tities of I/I that can be economically eliminated from a sewer syst em as determined in a cost-effectiveness analysis that compares the costs for correcti ng 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 Discharge—CWA Section 301(h) Variance CWA section 301(h) provides for variances from s econdary treatment standards for POTWs that discharge into ocean waters if the modified requireme nts do not interfere with attainment or maintenance of water quality. Permit writers should note that th e deadline to apply for a CWA section 301(h) variance (December 29, 1982) has passed, thus no ne w facilities may apply for this variance.
Eligible POTW applicants meeting the set of envi ronmentally stringent criteria in CWA section 301(h) receive a modified NPDES permit waiving the secondary treatment requirements for the conventional pollutants of BOD 5 , TSS, and pH. EPA issued regulations, developed the Amended Section 301(h) Technical Support Document 2 , and prepared a website titled Amendments to Regulations Issued, the Clean Water Act Section 301 (h) Program < www.epa.gov/owow/oceans/discharges/301h.html >. EPA has promulgated specific regulations pertaining to CW A section 301(h) that are provided in Part 125, Subpart G.
All CWA section 301(h) variance modified permits mu st contain the following specific permit conditions:

 Effluent limitations and mass loadings that w ill assure compliance with Part 125, Subpart G.

 Requirements for pretreatment program developm ent, 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 th e 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 ad justed standards apply and how that information was used to derive effluent limitations for the permit. The permit wr iter 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 limitati ons and standards that reflect pollutant reductions that can be achieved by categories, or subcat egories, of industrial point sources using specific

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technologies (including process changes) that EPA iden tifies 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 promulgate d by EPA are implemented through NPDES permits as authorized in CWA sections 301(a), 301(b), and 4 02. For sources that discharge to POTWs (indirect dischargers), EPA promulgates pretreatment standa rds that apply directly to those sources and are enforced by POTWs and state and federal authoriti es 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 fo r 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 na tional effluent guideline regulation, but they are applied to the circumstances relating to the applican t. 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. Secti on 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 Effluent Guidelines Congress saw the creation of a single national pollution control requirement for each industrial category, based on the best technology the industry could a fford, 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 th e 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 economicachievability of implementing the technology and the incremental costs in relation to the pollutantreduction benefits.
Effluent guidelines can include numeric and narrativ e limitations, including best management practices (BMPs), to control the discharge of pollutants from ca tegories of point sources. The limitations are based on data characterizing the performance of technologi es available and, in some cases, from modifying process equipment or the use of raw materials. A lthough the regulations do not require the use of any particular treatment technology, they do require fac ilities 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 pro cess changes necessary to meet the performance-based discharge limitations and standards sp ecified 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 f acilities that discharge directly to waters of the United States and another 12,000 facilities that disch arge into POTWs. The regulations prevent the discharge of more than 1.2 billion pounds of toxi c (priority) and nonconventional pollutants each year. EPA’s Effluent Guidelines Program Website < www.epa.gov/guide/ > provides information on existing effluent guidelines, current effluent guidelines rulema king, and the effluent guidelines planning process.



### 5.2.1.1 Statutory Foundation for Effluent Guidelines The CWA directs EPA to promulgate effluent guide lines 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 X X X New Direct Dischargers X Existing Indirect Dischargers X New Indirect Dischargers X

Pollutants regulated BPT BCT BAT NSPS PSES PSNS Conventional Pollutants X X X Nonconventional Pollutants X X X X X Toxic (Priority) Pollutants X X X X X

Best Practicable Control Technology Currently Available (BPT) BPT is the first level of technology-based effluent contro ls for direct dischargers and it applies to all types of pollutants (conventional, nonco nventional, and toxic). The Fede ral 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 a nd facilities, the processes employed, process changes, engineering aspects of the control technologies, no n-water quality environmental impacts (including energy requirements), and such other factors as th e EPA Administrator deems appropriate [CWA section 304(b)(1)(B)]. Traditionally, EPA establishes BPT efflue nt 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 hi gher 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)(1)(A) and 304(b)(1)(B).

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Best Conventional Pollutant Control Technology (BCT) The 1977 CWA requires EPA to identify effluent re duction levels for conventional pollutants associated with BCT for direct discharges from existing industri al 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 t echnologies, 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 additio n, 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 reducti on 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 po llutants 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

< www.epa.gov/npdes/pubs/fr_bct_1986.pdf >. 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-conventi onal 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 bene fit. 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 tr eatment 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 involve d, the process employed, process changes, non-water quality environmental impacts, including energy re quirements, 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 f acility’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 technol ogies at the time of construction. As a result, NSPS should represent the most stringent controls attain able through the application of the best available demonstrated control technology for all pollutant s (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 polluta nts 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 categor ical 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 nati onal 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 POTW s. PSNS are to be issued at the same time as NSPS. New indirect dischargers have the opportunity to incorporate into their fa cilities the best available demonstrated technologies at the time of constructi on. The Agency considers the same factors in promulgating PSNS as it considers in prom ulgating NSPS. See CWA section 307(c).
EPA typically does not establish pretreatment standards for conventional pollutants (e.g., BOD 5 , 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 interfere nce. 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 Sour ce 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 applicab le 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, th ough NSPS do not have specific dates as compliance deadlines, they are effective on the date the new sour ce begins discharging. The facility must demonstrate compliance with NSPS within 90 days of disch arge [see § 122.29(d)]. For more information on determining whether a discharge is subject to N SPS, 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 speci fic industrial sector by regulation after considering an in-depth engineering and economic analysis of the industrial sector. EPA’s Industrial Regulations Website < www.epa.gov/guide/industry.html > 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 performan ce 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 prom ulgated for various industrial categories in 40 CFR, Chapter I, Subchapter N - Effluent Guidelines and Standards - Parts 400-471 < www.epa.gov/lawsregs/search/40cfr.html >.

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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 vari ations 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 like lihood that the regulations are prac ticable and diminishes the need to address variations between facilities within a categor y 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 a nd 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 da ta 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 ev ery 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 indus trial category, and compliance with the effluent guidelines will ensure that similar metals present in th e 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 t echnology for effluent guidelines effectively treats the pollutant. For example, see Figure 6-1 Pollutant of Concern Methodology

< www.epa.gov/guide/cwt/final/develop/ch6.pdf > 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 th e preliminary effluent guidelines program plans presented on the Effluent Guidelines Biennial Plan Website < www.epa.gov/guide/304m/index.html >.

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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 di rectly 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. Th e 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. Th e limitations generally consist of upper bounds (maximum values) established for both th e 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 c ontrol is capable of achieving. That long-term average is calculated from data taken from facilities using the model te chnologies 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 consis tently because facilities with welldesigned and operated model tec hnologies have demonstrated that it can be done. The technical development document for the effluent guidelines usua lly 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 system s have inherent variability and, therefore, incorporates an allowance for this va riation into the limitations specifie d in the effluent guidelines. That allowance is based on statistical analysis of the da ta from facilities using the model technologies. The limitations included in effluent guidelines incorporat e 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 gui delines 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 th at 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 di schargers to provide ongoing control on a monthly basis that complements controls imposed by the maxi mum daily limitation. To meet the average monthly limitation, a facility must counterbalance a value n ear 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 m onthly limitation. As explained below, EPA uses a smaller percentile basis for the average monthl y 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 determ ine the values of the limitations specified in the effluent guidelines. Those procedures involve fitting e ffluent 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 perform s 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 tr anslated 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 sel ection 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 (D.C. Cir. 2002)]
Exhibit 5-9 depicts an example of TSS data for a f acility that is operating around a required long-term average level for TSS. The dots represent daily measure ments, and the reference lines show the values for the long-term average (LTA), the maximum daily li mitation (L1), and the average monthly limitation (L30). The facility has demonstrated compliance wi th both the maximum daily and average monthly limitations. Daily measurements include values both a bove 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 av erage 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., th e pollutant discharge is not to exceed the mass determined by multiplying the process wastewater fl ow 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

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 produc tion 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 effl uent guidelines as production-normalized mass-based effluent guidelines, “With the wide range of ope rations, 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 consisten tly attained throughout the industry.” [See 47 FR 38465, 31 August 1982.]

Numeric Limitations Established at Minimum Levels Using percentile estimates to set limitations in efflue nt guidelines is not a requirement under the CWA. In some cases, the model technology for treating a polluta nt might be capable of removing that pollutant to levels that cannot be reliably measured with ex isting analytical methods. EPA sometimes sets a requirement in the effluent guidelines that the concentr ation 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 po int 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 analy tical 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 <ML for papergrade sulfite (Subpart E) mills, which means “less than the minimum level specified in part 430.01(i)” (i.e., 10 picograms/liter for TCDF). If, in the future, analytical methods become more sensitive with lower MLs, EPA would determine whether the technologies for reducing the amount of the pollutant in the discharge are capable of achieving more stringent limitations and, thus, whet her it would be appropriate to modify the requirements of the effluent guideline.
EPA has not established average monthly limitations in effluent guidelines when the maximum daily limitation is an ML limitation. The purpose of an average monthly limitation is to require continuous dischargers to provide better control, on a monthly ba sis, than required by the maximum daily limitation. However, for these pollutants, the data were determin ed by analytical methods that could not measure below the ML specified in the regulations. Thus, even if a permitting authority requires monitoring for the pollutants more frequently than once a month, av erage monthly limitations would still be expressed as less than the ML or < ML

. Other Expressions for Numeric Limitations EPA also promulgates effluent guidelines for pollutant s that cannot be expressed in terms of mass or concentration (e.g., pH, temperature, radiation) or are better expressed through other means (e.g., unitless ratios). For example, pH is generally expressed as an acceptable range (e.g., 6.0–9.0 standard pH units).

Nonnumeric Effluent Limitations
In some cases, EPA includes nonnumeric or narrative e ffluent limitations rather than, or in addition to, numeric limitations in effluent guidelines. Nonnumeric effluent limitations might include specific BMPs or requirements to minimize or eliminate discharges. CWA sections 304(e), 308(a), 402(a), and 501(a) authorize the Administrator to prescribe BMPs as part of effluent guidelines and as part of an NPDES permit. CWA section 304(e) authorizes EPA to include supplemental BMPs in effluent guidelines for toxic or hazardous pollutants for the purpose of controlling “plant site runoff, spillage or leaks, sludge or waste disposal, and drainage from raw material st orage.” Several effluent guidelines include BMPs as requirements. Some effluent guidelines, such as the Concentrated Aquatic Animal Production point source category (Part 451), include the BMPs requireme nt exclusively. Section 9.1.2 of this manual further discusses BMPs.
CWA section 402(a)(1) and (2) and the NPDES regula tions at § 122.44(k) also authorize BMPs in NPDES permits to control or abate the discharge of pollutants when numeric effluent limitations are infeasible, or when the practices are reasonably necessary to achieve effluent lim itations and standards or to carry out the purposes and intent of the CWA.
Once EPA establishes effluent guidelin es, the permit writer is responsible for translating the limitations and other requirements of the effluent guidelines into TBELs and other conditions appropriate for inclusion in an NPDES permit. Section 5.2.2 belo w discusses a step-by-step approach for applying effluent guidelines through NPDES permits.

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### 5.2.2 Applying Effluent Guidelines through NPDES Permits Permit writers need to have a detailed knowledge of the industrial facility applying for a new or reissued NPDES permit to identify applicable effluent guide lines 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 efflue nt 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 effl uent 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 applic ation of effluent guidelin es in the fact sheet



### 5.2.2.1 Step 1: Learn About the Industrial Discharger To write a defensible permit, the permit writer s hould 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 informati on 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 an d wastewater treatment technology(ies).

 Discharge location of the wastewater polluta nts 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 assi st 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 Step 2: Identify the Applicable Effluent Guidelines Category(ies) As noted above, EPA’s effluent guidelines are at 40 CFR, Chapter I, Subchapter N - Effluent Guidelines and Standards, Parts 400–471 < www.epa.gov/lawsregs/search/40cfr.html >. A summary of promulgated effluent guidelines is presented on EPA’s Industrial Regulations Website < www.epa.gov/guide/industry.html > 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 Part Industry category (listed alphabetically) 40 CFR Part Aluminum Forming 467 Meat and Poultry Products 432 Asbestos Manufacturing 427 Metal Finishing 433 Battery Manufacturing 461 Metal Molding and Casting 464 Canned and Preserved Fruits and Vegetable Processing 407 Metal Products and Machinery 438

Canned and Preserved Seafood Processing 408 Mineral Mining and Processing 436 Carbon Black Manufacturing 458 Nonferrous Metals Forming and Metal Powders 471

Cement Manufacturing 411 Nonferrous Metals Manufacturing 421 Centralized Waste Treatment 437 Oil and Gas Extraction 435 Coal Mining 434 Ore Mining and Dressing 440 Coil Coating 465 Organic Chemicals, Plastics, and Synthetic Fibers 414

Concentrated Animal Feeding Operations (CAFOs) 412 Paint Formulating 446

Concentrated Aquatic Animal Production 451 Paving and Roofing Materials (Tars and Asphalt) 443

Copper Forming 468 Pesticide Chemicals 455 Dairy Products Processing 405 Petroleum Refining 419 Electrical and Electronic Components 469 Pharmaceutical Manufacturing 439 Electroplating* 413 Phosphate Manufacturing 422 Explosives Manufacturing 457 Photographic 459 Ferroalloy Manufacturing 424 Plastic Molding and Forming 463 Fertilizer Manufacturing 418 Porcelain Enameling 466 Glass Manufacturing 426 Pulp, Paper, and Paperboard 430 Grain Mills 406 Rubber Manufacturing 428 Gum and Wood Chemicals 454 Soaps and Detergents Manufacturing 417 Hospitals 460 Steam Electric Power Generating 423 Ink Formulating 447 Sugar Processing 409 Inorganic Chemicals 415 Textile Mills 410 Iron and Steel Manufacturing 420 Timber Products Processing 429 Landfills 445 Transportation Equipment Cleaning 442 Leather Tanning and Finishing 425 Waste Combustors 444 * This category contains only categorical pretreatment standards (no effluent guidelines for direct dischargers).

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 categor y 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 < www.census.gov/epcd/www/naics.html > and former SIC codes < www.census.gov/epcd/www/naicstab.htm > 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 est ablishments 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 s hould be cautious of relying exclusively on SIC codes for determining the appropr iate industrial category. SIC c odes were not developed using EPA’s industrial classification scheme, or vice ver sa, 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 l 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 categor y 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 wr iter might identify the applicable effluent guidelines using the facilities SIC codes.

Exhibit 5-12 Examples of identifying appli cable effluent guidelines using SIC codes
Example 1 A facility that performs the primary smelting and refini ng of copper reports SIC code 3331 in its NPDES permit application. By scanning the list of industri al 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 al so 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-ethylh exyl acrylate (acrylic acid esters) reports the SIC code 2869 (Industrial Organic Chemicals, Not Elsewher e 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 e ffluent guidelines. Such documents are extremely useful in identifying the applicability of the e ffluent guidelines and how to incorporate the effluent guidelines into NPDES permits. EPA ma y also publish a compliance guide for permit writers and industry. EPA’s Effluent Guidelines Website < www.epa.gov/guide/ > 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 insigh t into applicability of the effluent guidelines. EPA’s Effluent Guidelines Website < www.epa.gov/guide/ > provides FR notices for specific industrial categories. For example, the preamb les 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 exam ple, § 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

< www.epa.gov/guide /contacts.html > at its headquarters office in Washington, D.C. that are available to answer questions on specific effluent guidelines. EPA’s NPDES Contacts in Regional Offices

< www.epa.gov/npdes/regionalcontacts > 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 < http://water.epa.gov/lawsregs/lawsguidance/cwa/304m/ > provides technical support documents and other information supporting EPA’s biennial effluent guidelines program plans.

 EPA’s Sector Notebooks. EPA’s Sector Notebooks

< www.epa.gov/compliance/resources /publications/assistance/s ectors/notebooks/index.html > describe specific U.S. industries and governments and provide a holistic approach by integrating processes, applicable regulations, and other re levant environment information.

 Other Sources . Other sources of information include r esources identified below in Exhibit 5-23, BPJ Permitting Tools. Permit and fact sheet and in formation from similar facilities might aid in identifying applicable effluent guidelines. However, the permit writer should not assume that a similar facility was correct ly 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 varia tions 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 subcategor ies). 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 inform ation from the NPDES permit application.

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Exhibit 5-13 Examples of identify ing 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 effluent guidelines in the OCPSF point source category (Part 414) < www.epa.gov/guide/ocpsf/ >. The permit writer can determine from a further review of the industrial categorization discussion in the OCPSF Development Document and the guidance document that the facility is like ly subject to effluent guidelines in Subpart G (Bulk Organic Chemicals). Specifically, the applicability criteria se ction in Subpart G (§ 414.70) states, “The provisions of this subpart are applicable to the process wastewater disc harges resulting from the m anufacture 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 A large poultry slaughterhouse annually produces 200 milli on pounds of whole, halved, quarter or smaller meat cuts and reports SIC Code 2015 in its NPDES permit applicati on. The permit writer reviewed the list of effluent guidelines and identified that the facility is likely regulated by effluent guidelines in the Meat and Poultry Products point source category (Part 432) < www.epa.gov/guide/mpp/ >. 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 U.S. Census Bureau’s SIC to NAICS crosswalk website < www.census.gov/epcd/www/naicstab.htm > to identify the NAICS code (311615). Using the NAICS code, the permit wr iter can narrow the list of potentially applicable subcategories to the Poultry First Processing (Subpart K) or the Poultry Further Processing (Subpart L) subcategories. After reviewing the applic ability criteria of both s ubcategories, the permit wr iter determined that only the effluent guidelines in Subpart K are likely applicab le because the facility performs slaughtering operations, which are not regulated by Subpart L. Finally, the permi t writer also needed to compare the average annual production of the facility (200 million pounds) with the pr oduction threshold in the effluent guidelines (100 million pounds per year). Because the facility produces more than the production threshold, the effluent guidelines in Subpart K are 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), BOD 5 , fecal coliform, oil and grease (as HEM), TSS, and total nitrogen to derive effluent limitations as det ailed in section 5.2.2.5 below.



### 5.2.2.4 Step 4: Determine whether Existing or New Source Standards Apply

Section 5.2.1.1 above defines the different control t echnologies 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 wh ich construction began af ter promulgation of the applicable effluent guidelines or after proposal of the applicable efflue nt 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)(1).
Additional criteria for determining whether a dischar ge 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 r esult in a new source if any of the following is true for the source:

 Is constructed at a site at wh ich 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 e ffluent guidelines for the Pulp, Paper, and Paperboard Point Source Category in Part 430, include additiona l criteria for making new source determinations. See § 430.01(j).
Appendix D of this manual provides the applicab le new source dates used in making new source determinations by effluent guideline category as pr ovided in Appendix B of the EPA memorandum New Source Dates for Direct and Indirect Dischargers 4 < www.epa.gov/npdes/pubs /newsource_dates.pdf > sent by the directors of the Water Permits Division and the Engi neering 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 standa rds and other parts of the facility subject to new source standards. Permit writers should identify whet her 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 a pplying existing source requi rements 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, espec ially when modifications have occurred slowly over time. The permit writer should consult the effluent gu idelines regulation to determine if it defines more specifically what constitutes a new source.
It is important to remember that after the effective date of a new source standard, the CWA stipulates that it is unlawful for any owner or operator to operate su ch a source in violation of those standards. See 33 U.S.C. 1316(e) and 1317(d). EPA’s regulations speci fy 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)(1). 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 BOD 5 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 BOD 5 , 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 renderer.

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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)(1) stipulate that a ll 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 e xpressed in terms of other units of measure.

 If in establishing technology-based permit limita tions on a case-by-case basis, limitations based on mass are infeasible because the mass or polluta nt cannot be related to a measure of production (e.g., discharges of TSS from certain mining operatio ns). 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 guidelin es 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 discha rged, 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 efflue nt 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-base d and expressed in terms of allowable pollutant discharge per unit of production or some other me asure of production (i.e., production normalized). Permit writers incorporate such production-normalizedeffluent guidelines into NPDES permits as massbased 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 ma y 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 produ ction rate used in deriving mass-based effluent limitations is representative of the actual production like ly to prevail during the next term of the permit.
The examples in Exhibit 5-14 illustrate the applica tion 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 th e estimate of production. If historical trends, market forces, company plans to decrease production, or plan t designs and capital expenditures for an increase in production indicated that a different level of produc tion would prevail during the permit term, the permit writer could consider a different basis for estima ting 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 < www.epa.gov/waterscience/guide/ocpsf/ > 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 guide line] 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 Category 5

< www.epa.gov/waterscience/guide/ocpsf/#guidance > directs the permit writer to “use a reasonable estimate of process wastewater discharges and the concentration li mitations [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-normaliz ed 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 actua l daily flow rate (in terms of volume of process wastewater per day), which can reasona bly be expected to prevail during the next term of the permit (i.e., not the design flow rate). Permit writers can establish th at flow rate using the past 3 to 5 years of facility data in a manner similar to the method used to de termine production. For example, the permit writer might wish to use the highest average daily flow ra te 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-ba sed effluent limitation from productionnormalized effluent guidelines 6
Example 1 Facility A has produced 331,000 tons, 301, 500 tons, 321,500 tons, 330,000 tons, and 331,50 0 tons of product per year for the previous 5 year s 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 pe r 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 belo w) 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 producti on per day before comparing them. In this example, all the yearly production figures were based on 255 days per ye ar of production, so they may be compared directly. The 331,500 tons per year figure is the maximum for the pa st 5 years, which is only 2.6 percent above the average annual production of 323,100 tons. Ther efore, 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 an nual production of 331,500 tons, the production-normalized effluent guidelines for zinc are 0.1 lbs/1,000 lbs as m onthly average and 0.15 lbs/1,000 lbs 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 da ily 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 t he 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 ra te of 331,500 tons per year would yiel d an average production daily rate of 1,300 tons per day. Monthly average discharge limitation for zinc*: 1,300 tons/day x 2,000 lbs/ton x 0.10 lbs/1,000 lbs = 260 lbs/day Daily maximum discharge limitation for zinc*: 1,300 tons/day x 2,000 lbs/ton x 0.15 lbs/1,000 lbs = 390 lbs/day
* calculated to 2 significant figures

Calculating TBELs from Concentration-based Effluent Guidelines Permit writers might want to develop mass-based li mitations 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 effi cient use of water) and pollution prevention (e.g., reduce waste loads to wastewater tr eatment 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 technol ogies 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 limitati ons is that they provide the permittee with more flexibility. Permittees may elect to control their wast ewater 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, th e 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] × flow [mgd] × 8.34 [conve rsion factor] = permit limitation [lbs/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) 7 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 calcula tion 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 guidelin es. Mass-based limitations for unregulated or dilution wastewater streams at direct disch arging facilities are established using [BPJ].
Where a permit writer cannot determine a reasonable me asure 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 write rs to calculate mass-based TBELs, a permit writer may determine that it is beneficial to include c oncentration-based limitations to supplement the massbased limitations. Where effluent limitations are expr essed 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 expr essing limitations in terms of both concentration and mass encourages the proper operation of a treatment facility at all times.
Supplementing mass-based limitations with concentra tion-based limitations may be especially appropriate where the requirements in the effluent guidelin es 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 fl ow). 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 efflue nt 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 reducti on 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 app licable 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 impl emented through BMPs. Another example, related to monitoring and complian ce rather than effluent limitations, is found in the Metal Finishing effluent guidelines. The effluent gui delines allow a facility to make a statement regarding total toxic organics (TTO) in lieu of monitoring fo r 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) § 455.11(a).

Exhibit 5-15 Example narrative requirement from the Concentrated Aquatic Animal Production effluent guideline—Subpart A [§ 455.11(a)]
Except as provided in [§§] 125.30 th rough 125.32, any existing point source subject to this subpart must meet the following requirements, expressed as practices (or any mo dification to these requirements as determined by the permitting authority based on its exercise of its best prof essional judgment) representing the application of BPT:
(a) Solids control. The permittee must:
(1) Employ efficient feed management and feeding strate gies that limit feed input to the minimum amount reasonably necessary to achieve production goals and sust ain targeted rates of aquatic animal growth in order to minimize potential discharges of uneaten feed and wast e products to waters of the [United States]
(2) In order to minimize the discharge of accumula ted solids from settling ponds and basins and production systems, identify and implement procedures for routine cleaning of reari ng 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 proper ly 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 the aquatic environment.



### 5.2.2.6 Step 6: Account for Overlapping or Multiple Effluent Guidelines Requirements 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 app licable 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 a pplicability section in Part 433 [§ 433.10(b)], which specifically excludes certain wastewaters from the Me tal 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 guide lines 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
In some cases, effluent limitations and standards for the following industrial categories might be effective and applicable to wastewater discharges from the metal fini shing 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)

 Coil coating (40 CFR Part 465)

 Porcelain enameling (40 CFR Part 466)

 Battery manufacturing (40 CFR Part 461)

 Iron and steel (40 CFR Part 420)

 Metal casting foundries (40 CFR Part 464)

 Aluminum forming (40 CFR Part 467)

 Copper forming (40 CFR Part 468)

 Plastic molding and forming (40 CFR Part 463)

 Nonferrous forming (40 CFR Part 471)

 Electrical and electronic components (40 CFR Part 469)

Exhibit 5-17 Excerpts from pream ble to OCPSF effluent guidelin es regarding applicability of effluent guidelines

 For the purposes of this regulation, OCPSF process wa stewater discharges are defined as discharges from all establishments or portions of est ablishments that manufacture produc ts 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 wastew ater discharges from the manufacture of organic chemical compounds solely by extraction from plant an d 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 indust ry 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 refi neries 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 ot her 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 materi al for shipment off-site. The regulation also applies to the extrusion of fibers. Plastics molding and fo rming processes, other than those described above are regulated by the Plastics Molding and Forming effl uent guidelines and standards (40 CFR Part 463).

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Exhibit 5-17 Excerpts from pream ble to OCPSF effluent guidelin es regarding applicability of effluent guidelines (continued)

 Public comments requested guidance relating to the cove rage of OCPSF research and development facilities,standalone OCPSF research and development, pilot plant, technical service, and laboratory bench scaleoperations are not covered by the OCSPF regulation. However, wastewater fr om such operations conducted in conjunction with and related to existing OCPSF manufactu ring operations at OCPSF facilities is covered by the OCPSF regulation because these operations would most lik ely generate wastewater with characteristics similar to the commercial manufacturing facility. Research a nd development, pilot plant technical service, and laboratory operations [that] are unrelated to existi ng OCPSF plant operations, even though conducted on-site, are not covered by the OCPSF regulation because they ma y generate wastewater with characteristic dissimilar to that from the commercial OCPSF manufacturing facility.

 Finally, as described in the following paragraphs, th is 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 e ffluent 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 guide lines to derive TBELs. In applying multiple effluent guidelines, the permit writ er should use measures of actual production or flow that are reasonable with respect to operation of mu ltiple processes at the same time. For example, if maximum production for one process can occur only wh en 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 gui delines. 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 Primar y 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 re quirements 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 effl uent limit for lead at the facility?

Answer: BPT calculation for lead (§ 421.102): a) Tungstic acid rinse: (4.7 million lbs/day) × (17.230 lbs/million lbs) = 80.981 lbs/day b) Acid leach wet air pollution control: (4.7 million lbs/day) × (15.040 lbs/million lbs) = 70.688 lbs/day c) Alkali leach wash: (3.5 million lbs/day) × (0.000 lbs/million lbs) = 0.000 lbs/day d) Total allowable discharge = 80.981 + 70.688 + 0.000 = 151.669 = 152 lbs/day
BAT calculation for lead (§ 421.103): a) Tungstic acid rinse: (4.7 million lbs/day) × (11.490 lbs/million lbs) = 54.003 lbs/day b) Acid leach wet air pollution control: (4.7 million lbs/day) × (1.003 lbs/million lbs) = 4.7141 lbs/day c) Alkali leach wash: (3.5 million lbs/day) × (0.000 lbs/million lbs) = 0.000 lbs/day d) Total allowable discharge = 54.003 + 4.7141 + 0.000 = 58.7171 = 59 lbs/day *
The technology-based maximum daily limitation for lead at the facility is the BAT limitation of 59 lbs/day . That value is compared with the water quality-based effluent limit ation for lead, to ensure t hat 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 ot her 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, productionnormalized 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 concen tration-based limitation as the TBEL for the combined wastewater streams or convert the c oncentration-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 applicab le 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 coul d 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 wastewat er, the permit writer might use BPJ to apply the treatment standards for domestic wastewater and calculate BOD 5 limitations for that wastewater stream. The secondary treatment standards, di scussed 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 BOD 5 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 do es 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 a llowed under § 122.45(h) and in Step 7 below.
For examples of addressing combined wastewater st reams, see section 15.3.3 on page 15-10 of EPA’s Technical Development Document for the Final Efflu e nt Limitations Guidelines and Standards for the Meat and Poultry Products Point Source Category (40 CFR 432) 8

< www.epa.gov/waterscience/guide/mpp/final/tdd15.pdf >.
Facilities with Both New and Existing Sources Finally, as noted above, if effluent guidelines are applicab le 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 standard s 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 Regulator y 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 Discharge 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 fluctu ation 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 illustrat es application of tiered limitations.

Exhibit 5-19 Example of tier ed 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 fa ll and winter months during the previ ous 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 lbs for the average monthly limitation and 0.14 lbs/1,000 lbs for t he 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 × 2,000 lbs/ton x 0.08 lbs/1,000 lbs = 6.4 lbs/day* Daily maximum limitation: 40 tons/day × 2,000 lbs/ton x 0.14 lbs/ 1,000 lbs = 11.2 lbs/day = 11 lbs/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 × 2,000 lbs/ton x 0.08 lbs/1, 000 lbs = 44.8 lbs/day = 45 lbs/day* Daily maximum limitation 280 tons/day × 2,000 lbs/ton x 0.14 lbs/1, 000 lbs = 78.4 lbs/day = 78 lbs/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 pro duction (September through February), the higher limitations would be in effect. In a ddition, 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 limita tions on an expected incr ease 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 threshol ds and time frames when each tier applies, measures of production, and special reporting requirements. Sp ecial 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 le vel of production and the duration this level of production is expected to continue.

 The facility reporting, in the discharge monito ring report, the level of production and the limitation and standards applicable to that level.
A detailed discussion of the rationale and requirement s 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 an alytic 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 intern al 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 inte rnal 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 limite d 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 no t 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 w ill most likely be the person to conduct the initial reviews of such requests before submitting them for revi ew 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 (FDF) variance requests, which must be requested by th e 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. Exhi bit 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) Nonconventional Pollutant Part 125, Subpart F (Reserved) EPA Region HQ delegated authority During permit comment period

301(n) Fundamentally Different Factors (FDF) Part 125, Subpart D EPA Region HQ delegated authority 180 days from the date the limitation or standard is published in the FR

— Net Intake or Net/Gross § 122.45(g) NPDES state or EPA Region in absence of approved state NPDES program 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 Pollutant—CWA 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 mee ting 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 me asured 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 Powe r 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 di scharger 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 othe r 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 protec tion 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 i nvolve a great deal of water quality assessment, including aquatic toxicity, mixing zone a nd 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, bio accumulation, and synergistic propensities. Permit writers may use EPA’s Draft Technical Guidance Manual for the Regulations Promulgated Pursuant to Section 301(g) of the Clean Water Act of 1977 40 CFR Part 125 (Subpart F)

< www.epa.gov/npdes/pubs/owm0008.pdf > to assess a completed variance request.

Fundamentally Different Factors—FDF Variance

Alternative effluent limitations or standards differe nt 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 limita tions or standards otherwise applicable to that facility’s industrial category. Such a modification is known as a fundamentally different factors (FDF) variance.
Facilities must submit all FDF 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 FR [see CWA section 301(n)(2) and § 122.21(m)(1)(i)(B)(2)]. An FDF 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 FDF variance requests for direct dischargers. The regulations at § 12 5.31(d) identify six factors that may be considered in determining if a facility is fundamentally different:

 Nature or quality of pollutants cont ained 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 applicati on 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 engin eering 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 FDF 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 FDF 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 § 125.31(b)(3), a request for lim itations less stringent than the national limitation may be approved only if compliance with the national limita tions would result in either of the following:

 Removal cost wholly out of proportion to the rem oval cost considered during development of the national limitations.

 Non-water quality environmental impact (including energy requirements) fundamentally more adverse than the impact considered duri ng 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) under scores the necessity for the FDF variance applicant to establish eligibility for the variance. EPA’s regulati ons at § 125.32(b)(1) 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 f undamentally 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 regula tions 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 sp ecify 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 BOD 5 or TSS, are only authorized where the constituents resulting in the effluent BOD 5 and the TSS are similar between the intake water and the discharge.

 Credit is authorized only up to the extent necessar y 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 Discharge—CWA 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 promulga ted thermal limitations in effluent guidelines for two industrial sectors: Beet Sugar Processing Subcateg ory 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 st andards, 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 b ased on an effluent guideline or during the permit comment period if the thermal effluent limitation is based on a WQBEL.
Regulations for submitting and review ing thermal discharge variance requests are promulgated at Part 125, Subpart H. The approval authority for a therma l 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 permit s if the discharger properly demonstrates that such effluent limitations are more stringent than necessary to assure the protecti on 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 se ction 316(a) requires consideration of the change to the ambient water temperature because of an effluent discharge. T he studies provided by applicants to support their requests frequently includ e historical thermal data for the receiving water. Permitting authorities should be aware that the effect s of global climate change could alter the thermal profile of some receiving waters making the historical record of thermal condit ions 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 Re quirements 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 e ffluent 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 Op erations (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 Machin ery (Part 438), and Ore Mining and Dressing (Part 440) point source categories. The permit writer should identify any specific stormw ater 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 di scharges 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 TB ELs derived from effluent guidelin es. The effluent guidelines often require specific analytical methods. For example, the General Definitions section of the Meat and Poultry Products effluent guidelines [§ 432.2(l)] states, “The approved methods of analysis for the following six parameters [Ammonia (as N), BOD 5 , Oil and Grease (O&G), O&G as hexane extractable material (HEM), Total Nitrogen, TSS] are f ound in Table 1B 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 requirement s (e.g., solvent management plans, BMP plans, alternative monitoring requirements) may be include d in the applicable effluent guidelines. The permit writer should ensure that the documentation and reco rdkeeping 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 NPDE S 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 fo r 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 a nd 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 NP DES permit applicant and the public a transparent, reproducible, and defensible descr iption of how the NPDES permit properly incorporates effluent guidelines.
Similarly, permit writer should also document the ra tionale 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-by-Case TBELs for I ndustrial 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)(1), which authorizes the EPA Administrator to issue a permit that will meet eith er 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 taki ng 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) specifi cally 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)(1) of the Act, to the extent that EPA-p romulgated effluent limitations are inapplicable.” Further, § 125.3(c)(3) indicates that “where promul gated effluent limitations guidelines only apply to certain aspects of the discharger’s operation, or to cer tain pollutants, other aspects or activities are subjectto regulation on a case-by-case basis to carry out the provisions of the Act.” When establishing case-bycase effluent limitations using BPJ, the permit writer s hould 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 require ments 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 include s 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 di stilled 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 in dustry category, but no effluent guidelines are available for the facility subcategory (e.g., di scharges 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 in dustry category but are not applicable to the NPDES permit applicant (e.g., facilities that do no t 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 guid elines). 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 thatcase, any TBELs for the facility would be case-bycase limitations developed using BPJ because th e 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 con cern (e.g., a facility is regulated by the effluent guidelines for Pesticide Chemicals [Part 455] but di scharges 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 effl uent guidelines planning support documents on EPA’s Effluent Guidelines Biennial Plan Website < http://water.epa.gov/lawsre gs/lawsguidance/cwa/304m/ > identify facilities and industrial sectors that currently are not regulated by effluent guidelines.



### 5.2.3.3 Factors Considered When Developing Case-by-Case TBELs The NPDES regulations at § 125.3(c)(2) require th at 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 technolog y. That process and the factors considered by the permit writer are the same factors required to be co nsidered 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 cons idered 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 cost s 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 cont rols in NPDES permits that correspond to the application of an identified technol ogy (including process changes) but does not require dischargers to install the identified technology. Therefore, EPA l eaves to each facility the discretion to select the technology design or process changes necessary to m eet 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 candida tes 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 Wh en Establishing Case-by-Case TBELs The quality of the effluent from a treatment facility will normally vary over time. If, for example, BOD 5 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 frequencyconcentration plot. From the plot, one could observe that for most of the time, BOD 5 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) a nd 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 e ffluent guidelines. Specifically, the maximum daily limitation could be calculated by multiplying the lo ng-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 li mitation 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 statisti cal 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 f it to concentration data and variability factors computed for the facility distribution. The modifi ed 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 detec tion 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 permi ts issued to facilities in the same region or state, or that include case-by-case limi tations for the same pollutants.

 Toxicity reduction evaluations for selected industries.

 Other media permit files (e.g., Resource Conservati on and Recovery Act [RCRA] permit applications and Spill Prevention Countermeasure and Control [SPCC] plans.

 ICIS-NPDES < https://icis.epa.gov/icis > data.

 Literature (e.g., techni cal journals and books). Effluent guidelines development and planning information

 Industry experts within EPA headquarters, EPA Regions, and states < www.epa.gov/guide /contacts.html >.

 Development Documents, CWA section 308 questionnai res, screening and verification data, proposed and final regulations, contractor’s reports, and project officer contacts < www.epa.gov/guide >.

 EPA’s Technical Support Documents < http://water.epa.gov/lawsre gs/lawsguidance/cwa/304m/ > and records supporting EPA’s biennial effluent guidelines program plans also provide additional useful information. In particular, such resources provide a sample of the cu rrent limitation and latest developments in industrial pollutant prevention, water conservation, and wastewat er treatment. The Technical Support Documents also identify industrial sectors not curr ently regulated by effluent guidelines. Statistical guidance

 Effluent Guidelines Technical Development Support Docu ments, such as the Development Document for Final Effluent Limitations Guidelines and Standards for t he Iron and Steel Manufacturing Point Source Category
< www.epa.gov/guide/ >. Economics guidance

 Protocol and Workbook for Determining Economic Achievability for NPDES Permits 9

< www.epa.gov/npdes/pubs/protocol_npdespermits.pdf > and < www.epa.gov/npdes/pubs/workbook_econ_permits.pdf >.

 BCT Cost Test Guidance < www.epa.gov/npdes/pubs/owm0009.pdf >.
Guidance for BMP-based limitations

 Guidance Manual for Developing Best Management Practices (BMPs) 10

< www.epa.gov/npdes/pubs/owm0274.pdf >.

 Storm Water Management for Industrial Activiti es: Developing Pollution Prevention Plans and BMPs 11 < www.epa.gov/npdes/pubs/contents_indguide.pdf >.

 National Menu of Stormwater Best Management Practices < www.epa.gov/npdes/stormwater/menuofbmps >.

For more details on EPA’s use of statistical me t hods for developing effluent guidelines, refer to Development Document for Final Effluent Limitations Guidelines and Standards for the Iron and Steel Manufacturing Point Source Category < www.epa.gov/guide/ironsteel/reg/tdd.htm >.



### 5.2.3.6 Documenting Case-by-Case TBELs in the Permit Fact Sheet 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 sh eet 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.

5-48 Chapter 5: Technology-Based Effluent LimitationsSeptember 2010 NPDES Permit Writers’ Manual

Chapter 5: Technology-Based Effluent Limitations 5-49 1 U.S. Environmental Protection Agency. 1985. Draft Guidance for NPDES Permits and Compliance Personnel—Secondary 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 Agen cy. 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 Ex isting Point Source Category , EPA-440-1-76-083A. Page 92. U. S. Environmental Protection Agency, Office of Water and Hazardous Materials, Washington, DC. Public ation available on NEPIS Website

< www.epa.gov/nscep/ > as document 440176083A.

4 Boornazian, 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. < www.epa.gov/npdes/pubs/newsource_dates.pdf >.

5 U.S. Environmental Protection Agency. 1987. Development Document for Effluent Lim itations Guidelines and Standards for the Organic Chemicals, Plastics and Sy nthetic Fibers Point Source Category . EPA 440-1-87-009. Page IX-9.
< www.epa.gov/waterscience/ guide/ocpsf/#guidance >.

6 Jordan, J.W. 1984. Calculations of Production-Based Effluent Limits

. U.S. Environmental Protecti on Agency, Office of Water, Washington, DC. Memorandum, December 18, 1984. < www.epa.gov/npdes/pubs/owm0427.pdf >.

7 U.S. Environmental Protection Agency. 2001. Permit Guidance Document: Transportati on Equipment Cleaning Point Source Category (40 CFR 442) , p. 30

. EPA-821-R-01-021. U.S. Environmental Protecti on Agency, Office of Water, Washington, DC.

< www.epa.gov/waterscience/ guide/teci/tecguid.pdf >.

8 U.S. Environmental Protection Agency. 2004. Technical Development Document for the Final Effluent Lim itations Guidelines and Standards for the Meat and Poultry Produc ts Point Source Category (40 CFR 432), EPA-821-R-04-011. U.S. Environmental Protection Agency, Office of Water, Washington, DC. < www.epa.gov/waterscience/ guide/mpp/final/tdd15.pdf >.

9 Putnam, Hayes and Bartlett, Inc. 1982. Protocol and Workbook for Determining Econom ic Achievability for National Pollutant Discharge Elimination System Permits . U.S. Environmental Protection Agency , Permits Division, Washington, DC.

< www.epa.gov/npdes/pubs/protocol_npdespermits.pdf

. > and < www.epa.gov/npdes/pubs /workbook_econ_permits.pdf >

10 U.S. Environmental Protection Agency. 1993. Guidance Manual for Developing Best Management Practices (BMP) . EPA 833-B-93-004. U.S. Environmenta l Protection Agency, Office of Water, Washington, DC.

< www.epa.gov/npdes/pubs/owm0274.pdf >.

11 U.S. Environmental Protection Agency. 1992. Storm Water Management for Industri al Activities: Developing Pollution Prevention Plans and BMPs . EPA 832-R-92-006. U.S. Environmental Protection Agency, Office of Wa ter, Washington, DC.

< www.epa.gov/npdes/pubs/contents_indguide.pdf >.September 2010 NPDES Permit Writers’ Manual

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## CHAPTER 6. Water Quality-Based Effluent Limitations

When drafting a National Pollutant Discharge Elimin ation System (NPDES) permit, a permit writer must consider the impact of the proposed discharge on th e quality of the receiving wa ter. 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 tec hnology-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 efflue nt 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 of fish, shellfish, and w ildlife and recreation in and on the water ( fishable/swimmable ).
WQBELs are designed to protect water quality by en suring 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 limita tions 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 fi nal effluent limitations.

Exhibit 6-1 Developing effluent limitations

CWA section 301(b)(1)(C) requires that permits include any effluent lim itations 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., TB ELs) and existing effluent quality are not sufficient to comply with water quality standards and to, wher e 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.September 2010 NPDES Permit Writers’ Manual

After completing that process, the permit writer de termines the final effluent limitations, includes any compliance schedules and interim effluent limitations , as appropriate, and docum ents all his or her decisions and calculations.

Exhibit 6-2 Standards-to-permits process

This chapter provides basic information on the st andards-to-permits process. For m ore 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 < www.epa.gov/npdes > and Water Quality Standards Website < www.epa.gov/waterscience/standards >.



## 6.1 Determine Applicable Water Quality Standards
CWA section 303(c) and Part 131 establish the frame work 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 sta ndards 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 of fish, shellfish and wildlife, and recreation in and on the water (i.e., the CWA section 101(a)(2) fishable/swimmable goal). In establishing standards, states must consider the use and value of their waters for public water supplies, propagation of fish and wildlife, recreation, agriculture and industrial purposes, and navigation. The U.S. Environmental Protection Agency (EPA) has provided information regarding procedures for developing wate r quality standards in the Water Quality Standards Regulation at Part 131 and EPA’s Water Quality Standards Handbook: Second Edition 1

< www.epa.gov/waterscience/lib rary/wqstandards/handbook.pdf .> (hereafter WQS Handbook ). 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 wa ter quality standards adopted by states. The purpose of EPA’s review is to ensure th at 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 doe s not adopt the necessary changes within 90 days of notification of the disapproval, EPA must promptly propose and promulgate a re placement 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

< www.epa.gov/waterscience/s tandards/wqslibrary/ >. In addition, EPA’s Water Quality Standards: Laws and Regulations Website < www.epa.gov/waterscience/standards/rules/ > 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 Wate r 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 of fish, 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 men tioned in the CWA, with the exception of waste transport and assimilation, which are not acceptable d esignated 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 a ttainable. 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 scientif ic 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 § 131.11(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 so me cases, wildlife from the deleterious effects of pollutants. States establish narrative criteria wher e 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 th eir byproducts through biological, physical, and chemical processes.

 The effects of pollutants on biological co mmunity diversity, productivity, and stability.
EPA’s recommended criteria developed under CWA secti on 304(a) assist states in developing their water quality standards. EPA’s numeric criteria are ambient leve ls of individual pollutants or parameters or they describe conditions of a waterbody that, if met, gene rally will protect the CWA section 101(a)(2) fishable and swimmable uses. EPA’s recommended criteria de veloped 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 < www.epa.gov/waterscien ce/criteria/wqctable/ >. The regulation at § 131.11(b)(1) indicates that, in establis hing 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 publishe d recommended criteria if the discharge or presence of the pollutant can reasonably be expected to inte rfere with designated uses. Furthermore, § 131.11(a)(2) requires states to review water quality data and information on discharges to identify specific water bodies where toxic pollutants might be adversely affec ting water quality or attainment of designated uses or where levels of toxic pollutants would warrant c oncern 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-1 in Appendix C of this manual, the CWA section 307(a) list contains 65 compounds and families of compounds, which EPA h as interpreted to include 126 toxic (priority) pollutants.

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Numeric Criteria—Aquatic Life Numeric criteria for the protection of aquatic life ar e 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 speci es. 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 permi tting 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 < www.epa.gov/waterscien ce/criteria/wqctable/ > and at 66 FR 18935, April 12, 2001, Notice of Availability of 2001 Update: Aquatic Life Criteria Document for Cadmium < www.epa.gov/EPA-WATER/ 2001/April/Day-12/w9056.htm >.

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 [ μ g/L]) does not exceed the numerical value given by

e (0.7409[ln(hardness)]-4.719) (1.101672 – [(ln hardness)(0.041838)]) mo re than once every 3 years on average.
Acute criterion: The 24-hour average concentration (in μ g/L) does not exceed the numerical value given by

e (1.0166[ln(hardness)]-3.924) (1.136672 – [(ln hardness)(0.041838)]) mo re 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 durati on (4-day average or 24-hour average), and a frequency (not more than once every 3 years). Furtherm ore, 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 of fish. A permit writer must be aware of the applicable criteria and any state regulations, policies, and procedures fo r interpreting numeric criteria and for implementing the criteria in NPDES permits. The durations of aqua tic 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 ex ceeded 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 asso ciated with the prevention and assessment of eutrophic conditions. EPA’s recommended nu trient 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 cr iteria, and they can be refined and localized using nutrient criteria technical guidan ce manuals. Second, the recommended nutrient criteria represent conditions of surface waters that have mini mal impacts caused by human activities rather than values derived from laboratory toxicity testing. Th ird, the recommended nutrient criteria are do not include specific duration or frequency components; how ever, the ecoregional nutrient criteria documents indicate that states may adopt seasonal or annual averag ing 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 othe r information on EPA’s nutrient criteria recommendations, are available on the Water Quality Criteria for Nitrogen and Phosphorus Pollution Website < www.epa.gov/waterscience /criteria/nutrient/ >.
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 pollu tant parameters, many states include in their water quality standards criteria for dissolved oxygen. Ofte n, 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), a nd 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 mixtur e of pollutants. WET is discussed in detail later in this chapter.

Numeric Criteria—Human Health Human health criteria for toxic pollutants are designed to protect people from exposure resulting from consumption of fish or other a quatic organisms (e.g., mussels, cray fish) 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 effect s of dichlorobromomethane through ingestion of water and contaminated aquatic organisms, the ambient wate r criterion is determined to be 0.55 μ g/L. For the protection of human health from the potential carcinogenic effect s of dichlorobromomethane through ingestion contaminated aquatic or ganisms alone, the ambient water cr iterion is determined to be 17 μ g/L.
These values were calculated based on a national def ault freshwater/estuarine fish consumption rate of 17.5 grams per day.

Other criteria for protection of human health (e.g., bacteria criteria) consid er 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 si ngle sample maximum value. EPA has developed information on implementing those criteria in water quality standards on the Microbial (Pathogen) Water Quality Criteria Website < www.epa.gov/waterscien ce/criteria/huma nhealth/microbial/ >.

Other Numeric Criteria In addition to aquatic life and huma n 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 re sulting from exposure to those chemicals through consumption of aquatic organisms a nd water. EPA established four numeric criteria to protect wildlife in the Great Lakes system in its Final Water Quality Guidan ce for the Great Lakes System

< www.epa.gov/EPA-WATER/1995/March/Day-23/pr-82.html > (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

< www.epa.gov/waterscience /criteria/sediment/ >.
The presence, condition and numbers of types of fish, in sects, algae, plants, and other organisms are data that, together, provide direct, accurate information ab out the health of specific bodies of water. Biological criteria (biocriteria) are narrative or numeric expressi ons that describe the reference biological integrity (structure and function) of aquatic communities inhab iting waters of a given designated aquatic life use. Biocriteria are based on the numbers and kinds of or ganisms present and are regulatory-based biological measurements. They are used as a way of describing th e qualities that must be present to support a desired condition in a waterbody, and they serve as the standa rd against which biologi cal assessment results are compared. EPA’s Biocriteria: Uses of Data in NPDES Permits Website

< www.epa.gov/waterscience/biocr iteria/watershed/npdes.html > provides more information on the use of bioassessment information.

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Narrative Criteria All states have adopted narrative water quality criteri a 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 criteri a can be the basis for limiting specific pollutants for which the state does not have numeric criteria [§ 122. 44(d)(1)(vi)] or they can be used as the basis for limiting toxicity using WET requirements where the toxici ty has not yet been traced to a specific pollutant or pollutants [§ 122.44(d)(1)(v)]. For toxic pollutant s, EPA’s Water Quality Standards Regulation at § 131.11(a)(2) requires states to develop implementa tion 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 cons istent with EPA’s antidegradation regulations at § 131.12. A state’s antidegradation policy specifies the fra mework to be used in making decisions about proposed activities that will result in changes in water quality. Antidegra dation policies can play a critical role in helping states protect the public resource of water whose qua lity is better than established criteria levels and ensure that decisions to allow reductions in wate r 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 implemente d 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 of fish, shellfish, and wildlife and recreation in a nd 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 inter governmental coordination and public participation provisions of the state’s continuing planning pr ocess, 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 degrada tion or lower water quality, the state must assure water quality adequate to protect existing uses full y and must assure that there will be achieved the highest statutory and regulat ory requirements for all new a nd 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 Ti er 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-relate d 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 polici es, critical low flows at which criteria must be achieved, and the availability of variances. Some genera l policies are discussed in more detail later in this chapter. As with the other components of water qua lity standards, general policies are subject to EPA review and approval if they are deemed to be ne w or revised water quality standards (i.e., if they constitute a change to designated use(s), water qua lity criteria, antidegradation requirements, or any combination).

Additional and more detailed info rmation 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 wate rbody or segment, that use may not be removed from the water quality standards except under specific cond itions. To remove a designated use, the state demonstrates that attaining that use is not feasibl e because of any one of the six factors listed in § 131.10(g). The regulations at § 131.10(j) specifical ly 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 subcategor ies 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 qua lity 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 < www.epa.gov/waterscience/sta ndards/uses/uaa/index.htm > 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 no t adequately account for site-specific conditions. In such cases, states have the option ofmodifying water quality criteria on a site-specific basis. Setting sitespecific 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 t ypes of local aquatic organisms differ significantly from those actually tested in developing the EPA-recommende d criteria. Site-specific criteria modifications change water quality criteria perman ently while continuing to suppo rt the current designated uses.
Development of site-specific criteria for aquatic lif e 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 Proce dure) and (2). the species at the site are more or less sensitive than those used in developing the natu ral 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 < www.epa.gov/waterscience/st andards/handbook/handbookappxL.pdf > in Appendix L of the WQS Handbook and the Streamlined Water-Effect Ratio Procedure for Discharges of Copper 2 < www.epa.gov/waterscience/c riteria/copper/copper.pdf >. 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 3

< www.epa.gov/waterscience/library/wqcriteria/naturalback.pdf >

.


### 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 be lieves that the existing standards are ultimately attainable and that, by retaining the existing standard s 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 ou tlined 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 secti on 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 funda mental basis for WQBELs, potentially affecting an assessment of the need for WQBELs and possibly resulti ng in either more or less stringent WQBELs than

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would otherwise be required. It is the permit wr iter’s responsibility to ensure that any EPA-approved modification of water quality standards is prope rly reflected in an affected NPDES permit.



### 6.1.3 Water Quality Standards Implementation As previously noted, CWA section 301(b)(1)(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. E ach 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 Control 4 < www.epa.gov/npdes/pubs/owm0264.pdf > (hereafter TSD ). Those procedures were developed specifically to addres s 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, Pennsylv ania, and Wisconsin were required to adopt procedures for the Great Lakes system that are cons istent 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-speci fic 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 fo r 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 wa ter. Parameter-specific WQBELs in NPDES permits involve a site-specific evaluation of the discharge (o r 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] anal ysis). The parameter-specific approach allows for controlling individual parame ters, (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 pr otect 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 comple x effluents where it might be infeasible to identify

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and regulate all toxic pollutants in the effluent or wh ere parameter-specific effluent limitations are set, but the combined effects of multiple pollutants are suspect ed 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 amount s” criterion. Like the parameter-specific approach, the WET approach allows permitting authorities to contro l toxicity in effluents before toxic impacts occur or may be used to help retu rn water quality to a level that will meet designated uses.



### 6.1.3.3 Bioassessment Approach The biocriteria approach is used to assess the overa ll biological integrity of an aquatic community. As discussed in section 6.1.1.2 above, biocriteria are nume ric 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 representativ e 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 fo r the designated use of the waterbody are being met. EPA issued guidance on this approach in Biological Criteria: National Program Guidance for Surface Waters 5 < www.epa.gov/bioindicator s/html/biolcont.html >. As previously discussed, biocriteria generally are not directly implemented through NPDES permits but c ould be used in assessing whether a waterbody is attaining water quality standards. N onattainment of biocriteria could l ead 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 Waterbody Website < www.epa.gov/waterscience/biocr iteria/uses/stressors.html >) or could lead to WET limitations where the permitting authority identifies sour ces of toxicity to aquatic life. EPA’s Biocriteria: Uses of Data - NPDES < www.epa.gov/waterscience/biocr iteria/watershed/npdes.html > provides examples on the use of bioassessment information in the NPDES permitting process.
Sections 6.2–6.4 below discuss, in detail, implem enting water quality standards using the parameterspecific approach to assess the need for and develop effluent limitations in NPDES permits. Section 6.5 below provides additional detail on WE T requirements in NPDES permits.



## 6.2 Characterize the Effluent and the Receiving Water
After identifying the most current, approved, water qua lity standards that apply to a waterbody, a permit writer should characterize both the effluent discharge d by the facility being permitted and the receiving water for that discharge. The permit writer uses the in formation 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 characterizin g 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 receiv ing water critical conditions Step 5. Establish an appropriate di lution 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 wate r characterization to assess the need for WQBELs (section 6.3 below). The following subsections identif y 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 standa rds 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 ab ove). A permit writer can determine whether the TBELs are sufficiently protective by either proceedi ng to calculate WQBELs as described in section 6.4 below and comparing them to the TBELs or by assu ming that the maximum daily TBEL calculated is the maximum discharge concentration in the water qua lity 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 ha ve installed the minimum require d 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 wate r’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 wa terbody can be used for the purposes designated in the water quality standards, to provide for the uncerta inty 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

TMDL = Σ WLA + Σ LA + Margin of Safety + Reserve Capacity
The NPDES regulations at § 122.44(d)(1)(vii)(B) require that NPDES permits include effluent limitations developed consistent with the assumptions and require ments 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 whethe r 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. Perm itting 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. Perm it writers must determine whether the conditions leading to a decision to include WQBELs for the pollu tant 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 re quirements 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 iden tified as present in the effluent through effluent monitoring. Effluent monitoring data are reporte d 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 effl uent 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 fac ility 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 da ta, 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 Wate r Quality Standards Provide for Consider ation of a Dilution Allowance or Mixing Zone Many state water quality standards have general pr ovisions 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 an y type of waterbody wher e initial dilution of a discharge takes place and within which the water qualit y 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 polici es might indicate specific locations or conditions (e.g., breeding grounds for aquatic species or bathi ng 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 Wat er Interactions

Where consideration of a dilution allowance or mixing zone is not permitted by the water quality standards or is not appropriate, the relevant wate r 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 permitte d, 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 th is 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 qualit y 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 Effl uent and Receiving Wate r 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. Identifyi ng 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 modeler s, 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 WQBEL s 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 identificat ion 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 Q d 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 da ta from discharge monitoring reports or a permit application. Permitting authority policy or procedur es 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 y ears, the facility design flow). Permit writers should follow existing policy or procedures for determining cr itical 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 con centration of the pollutant of concern (designated C d ) by gathering effluent data representative of the di scharge. To establish the critical effluent pollutant concentration from the available data, EPA has reco mmended 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)(1)(ii) require that permit writers consider the variability of the pollutant in the e ffluent 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, EP A 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 statis tical 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 coeffici ent 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 lognorma l distribution of effluent pollutant concentrations and projection of a critical effluent pollutant concentration (C d ). For additional details regarding EPA’s guidance, see Chapter 3 of the TSD. Many perm itting 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 th eir 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 (C d )

CVRelative frequency

C d (projected critical pollutant concentration in the effluent) Concentration



### 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 m odels. In addition, depe nding on the waterbody and pollutant of concern, there could be additional recei ving water characteristics that permit writers need to consider in a water quality model.

Receiving Water Upstream Flow For rivers and streams, an important critical cond ition is the stream flow upstream of the discharge (designated Q s ). That critical condition generally is specified in the applicable water quality standards and reflects the duration and frequency components of th e 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 fo r 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 ups tream of the discharge. The permit writer might also account for any additional sources of flow or diversio ns 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 upstre am 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 cr itical 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. Geol ogical Survey. Modelers sh ould 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 cu rrent and future critical fl ows. Where appropriate, water quality modelers should consider alternate appr oaches to establishing critical low flow conditions that account for these climatic changes.

Receiving Water Background Pollutant Concentration In addition to determining the critical effluent concen tration of the pollutant of concern, the permit writer also should determine the critical background concentra tion of the pollutant of concern in the receiving water before the discharge (designated C s ) 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 polluta nt. 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 re liable characterization of receiving water background pollutant concentration. EPA encourages permitting au thorities 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 am bient 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 ac tivity and reaction chemistry might be important in assessing the impact of a discharge on the receiving wate r. 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 pr esence 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 Allowa nce or Mixing Zone Following verification of whether the applicable wa ter quality standards allo w 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 dete rmination, 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 standa rds, the dilution allowance or mixing zone used in water quality models and calculations are likely to va ry 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 latera l variation in the concentration of a pollutant in the direct vicinity of the outfall is sm all. 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 occu rs more slowly and higher concentr ations 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 Allo wance 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 th e type of mixing taking place (rapid and complete mixing versus incomplete mixing), he or she would ag ain consult the water quality standards to determine the maximum size of the dilution allowance or mixi ng 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 stream s 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 allowan ce 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 allo wance, 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 downstr eam of the discharge being permitted. Recall as well that for some pollutants (e.g., pathogens in wa ters designated for primary contact recreation, bioaccumulative pollutants), the water quality standa rds 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 th an 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 certa in water quality criteria to be exceeded. While the criteria may be exceeded within the mixing zone, th e use and size of the mixing zone must be limited such that the waterbody as a whole will not be impair ed 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 geomet ric shape inside of which a water quality criterion may be exceeded. The geometric sh ape 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

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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 wate r 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 maxi mum mixing zone sizes and dilution allowances.

Exhibit 6-9 Examples of maximu m mixing zone sizes or dilution allowances under incomplete mixing conditions by waterbody type*

For rivers and streams:

 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

For lakes and the ocean:

 Mixing zones for lakes cannot be la rger than 5% of the lake surface

 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 proc edures 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, pollu tant of concern, and specific criterion being considered.



### 6.2.5.3 Restrictions on Dilution Allowance or Mixing Zone Size In addition to specifying the maximum dilution allowance or mixing zone size allowed under both rapid and complete mixing conditions a nd incomplete mixing conditions, the water quality standards or implementation policies generally include constraint s 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 acu te 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 maxi mum size allowed by the water quality standards or to not allow any acute mixing zone at all. Other po ssible 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 sta ndards 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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### 6.3.1 Defining Reasonable Potential EPA regulations at § 122.44(d)(1)(i) state, “Limitations must control all pollutants or pollutant parameters (either conventional, nonconventional, or toxic pollutant s) 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 sta ndard, including [s]tate narrative crite ria for water quality.” [emphasis added] Because of that regulation, EPA and many au thorized NPDES states refer to the process that a permit writer uses to determine whether a WQ BEL 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 conditio ns arrived at by making a series of reasonable assumptions, could lead to an excursion above an a pplicable 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 a nd modeling techniques, as described above, or using a non-quantitative approach. Both a pproaches are discussed below.



### 6.3.2 Conducting a Reasonab le Potential Anal ysis Using Data 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 availa ble 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 limitati on development whenever possible. Monitoring should begin far enough in advance of pe rmit 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 fo r the permit writer to include a reopener condition in the permit to allow the incorporation of a WQBEL if the mon itoring data indicate that a WQBEL is required.
A reasonable potential analysis conducted with availabl e 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 poten tial analysis with available data Step 1. Determine the appropriate water quality model Step 2. Determine the expected receiving wate r concentration under critical conditions Step 3. Answer the question, “I s there reasonable potential?” Step 4. Document the reasonable pot ential determination in the fact sheet



### 6.3.2.1 Step 1: Determine the Appropriate Water Quality Model 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 dischar ge 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 th e 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 reac tion chemistry should be mode led, 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 additio nal information, permit writers should discuss modeling that accounts for biological activity or reac tion chemistry with water quality modelers or other water quality specialists as needed and consult EPA’s Water Quality Models and Tools Website

< www.epa.gov/waterscience/models/ >.
For many pollutants such as most toxic (priority) pollutants, conservative pollutants, and pollutants that can be treated as conservative pollutants when near-fi eld 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

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)

Q s C s + Q d C d = Q r C r where Q s = stream flow in mgd or cfs above point of discharge C s = background in-stream pollutant concentration in mg/L Q d = effluent flow in mgd or cfs C d = effluent pollutant concentration in mg/L Q r

= resultant in-stream flow, after discharge in mgd or cfs C r

= resultant in-stream pollutant concentrat ion in mg/L (after co mplete mixing occurs)

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### 6.3.2.2 Step 2: Determine the Expected Receiv ing 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 wh ere there is incomplete mixing and then provides a detailed discussion of this analysis for situati ons where there is rapid and complete mixing.

How are critical conditions defined? When using a steady-state water quality model, permit wr iters 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-bas ed permitting, the permit writer should follow the permitting authority’s policies and procedures for select ing the critical conditions to use in a steadystate 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 determin e 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 Placi d River. The concentration of the pollutant of concern discharged by Acme Co. (Pollutant Y) is hi ghest nearest the point of discharge and gradually decreases until the pollutant is completely mixed w ith 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

Expected Receiving Water Concentration in Rapid and Complete Mixing Situation For many pol lutants, if there is rapid and complete mi xing 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 whic h 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 valu e for each variable and solve the equation for C r , 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 C r . 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 multip le 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 co mplete 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

The mass-balance equation can be used to determine w hether the discharge from ABC Inc., would cause, have the reasonable potential to c ause, or contribute to an excursio n above the water quality standards applicable to Pristine Creek. The equation is used to pred ict 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)

Q s C s + Q d C d = Q r C r where Q s = critical stream flow in mgd or cfs above point of discharge C s = critical background in-stream pollutant concentration in mg/L Q d = critical effluent flow in mgd or cfs C d = critical effluent pollutant concentration in mg/L Q r

= resultant in-stream flow, after discharge in mgd or cfs (Q r = Q s + Q d ) C r

= resultant in-stream pollutant concentrat ion in mg/L (after co mplete mixing occurs) Rearrange the equation to determine the concentration of Pollutant Z in the waterbody downstream of a discharge under critical conditions:

r ss dd
r Q ))(CQ())(C(Q C 



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Exhibit 6-14 Example of applying mass-balanc e equation to conduct reasonable potential analysis for conservative pollutant under conditions of rapid and complete mixing

Mass-Balance Equation: Q s C s + Q d C d = Q r C r
Dividing both sides of the mass-balance equation by Q r gives the following:

r ss dd
r Q ))(CQ())(C(Q C 



where C r is the receiving water concentration downstream of the discharge
The following values are known for ABC Inc. and Pristine Creek: Q s = critical upstream flow (water qualit y standards allow a dilution allowance of up to 100% of 1Q10 low flow for rapid and complete mixing) = 1.20 cfs C s = critical upstream concentration of Po llutant Z in Pristine Creek = 0.75 mg/L Q d = critical discharge flow = 0.55 cfs C d = statistically projected critical discharge concentration of Pollutant Z = 2.20 mg/L Q r

= downstream flow = Q d + Q s = 0.55 + 1.20 = 1.75 cfs Acute aquatic life water quality criterion for Pollutant Z in Pristine Creek = 1.0 mg/L
Find the projected downstream concentration (C r ) by inserting the given values into the equation as follows:

cfs) (1.75 mg/L) cfs)(0.75 (1.20)mg/L cfs)(2.20 (0.55 C r 



C r = 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 pollu tant 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, reas onable potential would occur if the water quality model indicates that the projected effluent c oncentration 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 potenti al 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 (μg/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 Po llutant Y exceeds 2.0 μg/L. Therefore, there is reasonable potential, and the permit writer must calculate WQBELs for Pollutant Y for Acme Co.

Exhibit 6-15 Reasonable potential determinat ion in an incomplete mixing situation

Reasonable Potential Determination in a Rapid and Complete Mixing Situation In the rapid and com plete mixing example for ABC, Inc., shown in Exhibit 6-14 above, a projected downstream concentration (C r ) 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 criteri on; therefore, there is a reasonable potential for the water quality criterion to be exceeded, and the perm it writer must calculate WQBELs for Pollutant Z.
A permit writer should repeat the reasonable potential an alysis for all applicable criteria for the pollutant of concern and must remember that the critical c onditions could differ depending on the criterion being evaluated. For example, the critical stream flow u sed 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 pe rmit writers to remember that they must repeat the reasonable potential analysis for each pollutant of concern and calcula te WQBELs where there is reasonable potential. For each pollutant for which there is no reasonable potenti al, 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 Chap ter 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 Po tential 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 clear ly identify the information and procedures used to determine the need for WQBELs. The goal of th at 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 includi ng or not including a WQBEL for any pollutant of concern.



### 6.3.3 Conducting a Reasonab le Potential Analys is without Data State implementation procedures might allow, or ev en require, a permit writer to determine reasonable potential through a qualitative assessme nt 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 th at 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 pe rmits for POTWs discharging to contact recreational waters).
Types of information that the permit writer might fi nd 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 existi ng 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 provi de 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 characteriz ing the nature of the discharge without effluent monitoring data for the pollutant of concern, if th e 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 condi tion of the newly issued or reissued permit. The permit writer might also include a clause in the perm it that would allow the permitting authority to reopen the permit and impose an effluent limitation if the requ ired 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 po llutant parameter is discharged at a level that will cause, have reasonable potential to cause, or contribu te 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 w ith effluent concentrations that tend to follow a lognormal distribution. Permit write rs should consult permitting author ity policies and procedures to determine the methodology specific to their authorized NPDES permitting program, including the approach for pollutants with effluent concentra tions that do not follow a lognormal distribution.



### 6.4.1 Calculating Parameter-specific WQBE Ls 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 averag e (LTA) concentrations for each WLA Step 3. Select the lowest LTA as the per formance basis for the permitted discharger Step 4. Calculate an average monthly limitation (AML) and a ma ximum daily limitation (MDL) Step 5. Document the calculatio n 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 firs t 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 concentrati on 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 wh ere a separate WLA is needed to address the nearfield effects of a discharge on water quality criteria, permit writers will, in many situations, use a steadystate 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 r eceiving 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 c onsidering near-field effects, if there is rapid and complete mixing in the receiving water. For pollutant s 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-balan ce 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 ra pid and complete mixing.



### 6.4.1.2 Step 2: Calculate LTA Concentrations for Each WLA The requirements of a WLA generally must be interp reted 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 availabl e 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 WQ BELs, the permit writer develops limitations that require a facility to perform in such a way that the co ncentration of the pollutant of concern in the effluent discharged is nearly always below the WLA.
To accomplish that goal, EPA has developed a sta tistical permit limitation derivation procedure to translate WLAs into effluent limitations for pollutants with effluent concen tration 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 WQB ELs 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 rec ognize that alternative procedures would be used to calculate effluent limitati ons 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

Mass Balance Equation: Q s C s + Q d C d = Q r C r where Q s = background stream flow in mgd or cfs above point of discharge C s = background in-stream pollutant concentration in mg/L Q d = effluent flow in mgd or cfs C d = effluent pollutant concentration in mg/L = WLA Q r

= resultant in-stream flow, after discharge in mgd or cfs C r

= resultant in-stream pollutant concentrat ion in mg/L (after co mplete mixing occurs)
Rearrange the equation to determine the WLA (C d ) for ABC Inc., necessary to achieve the acute water quality criterion for Pollutant Z in Pristine Creek (C r ) downstream of the discharge:

d ssrr d Q CQCQ C 


The following values are known for ABC Inc., and Pristine Creek: Q s = critical upstream flow (water qualit y standards allow a dilution allowance of up to 100% of 1Q10 low flow for rapid and complete mixing) = 1.20 cfs C s = upstream concentration of Pollutant Z in Pristine Creek = 0.75 mg/L Q d =discharge flow = 0.55 cfs Q r

= downstream flow = Q d + Q s = 0.55 + 1.20 = 1.75 cfs C r

= 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:

cfs) 55.0( mg/L)75.0 cfs)(20.1( mg/L)0.1 cfs)(75.1( C Inc. ABCforWLA d 


C d = 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 a nd by the CV, a measure of the variability of data around the LTA. Exhibit 6-18 illustrates a lognormal dist ribution 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 LTAs—one that would ensure that an effluent concentr ation is nearly always below the acute WLA and one that would ensure that an effluent concentration n early 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



### 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 calcula ted 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 Monthl y 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 di scharges other than POTWs and as both AMLs and average weekly limitations (AWLs) for POTWs. The AM L 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 cal endar week. For pollutants with limitations expressed in units of mass, the daily discharge is the total ma ss discharged over the day. For limitations expressed in other units, the daily discharge is the average measure ment of the pollutant over the period of a day.Relative frequency

CV

LTA WLA
Concentration

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In the TSD, EPA recommends establishing an MDL, ra ther 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 requirement s 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 pollu tants 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 author ity in its policies, procedures, or guidance.
Whether using the TSD procedures or other proce dures 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 lo w 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 in formation 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 H ealth Criteria for Toxic Pollutants Developing WQBELs for toxic pollutants affecting hum an health is somewhat different from calculating WQBELs for other pollutants because (1) the exposure pe riod of concern is generally longer (e.g., often a lifetime exposure) and (2) usually the average expos ure, 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 concen trations 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 chemi cal-specific WQBELs from human health criteria, he or she should compare the limitations to any other calculated WQB ELs (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 wa ter quality standards. As discussed above, that process should be documented in the fact sheet for the NPDES permit.

Chapter 6: Water Quality-Based Effluent Limitations 6-35September 2010 NPDES Permit Writers’ Manual



## 6.5 Calculate Reasonable Potential and WQBELs for WET
WET tests measure the degree of response of exposed aqua tic 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 (TST)

At the time of the writing of this guidance manual, EPA had recently published a new statistical approach that assesses the whole effluent toxici ty (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 meth od that uses hypothesis testing techniques based on research and peer-reviewed publications. The hy pothesis 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 unaccept able amount (the amount that would have a measured detrimental effect on the ability of aquatic organism s to thrive and survive). The TST implementation document and the TST technical do cument are available at the NPDES WET Website

< www.epa.gov/npdes/wet >.



### 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 typi cal dilution series used in WET testing.

Exhibit 6-19 Example of typical dilution series

Percent Dilution Wate r

Percent Effluent 100 50 25 12.5 6.25 100

0 0 50 75 87.5 93.75

There are two types of WET tests: acute and chronic. An acute toxicity test usual ly is conducted over a short time, generally 96 hours or less, and the endpoi nt measured is mortality. The endpoint for an acute test is often expressed as an LC 50 (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-leth al 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 hi ghest 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), th e lowest concentration of effluent that causes observable adverse effects in exposed test organisms.

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 Inhibition concentration (IC), 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 give n percentage of test organisms.
For additional information on WET monitoring and W ET test methods, see section 8.2.4 of this manual.



### 6.5.2 Expressing WET Limitations or Test Results There are two options for expressing WET limitations or t est results. First, WET limitations or test results can be expressed directly in terms of the WET test endpoints discussed above (e.g., LC 50 , NOEC, and IC 25 ). 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 di vided 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 LC 50 of 60 percent, that resu lt can be expressed as
TU 7.1unitstoxic acute 7.1 60 100

a  

If a chronic test result is an IC 25 of 40 percent effluent, that result can be expressed as
TU 5.2unitstoxic chronic 5.2 40 100

c  

It is important to distinguish acute TUs (TU a ) from chronic TUs (TU c ). The difference between TU a and TU c 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 TU a and TU c are expressions of the toxicity of an effluent, but 1.0 TU a is not the same as 1.0 TU c . 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 possi ble to determine the relationship between miles and kilometers (i.e., through a conversion factor). Unlik e the conversion between miles and kilometers that remains constant, the conversion factor between acut e 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 TU a into equivalent TU c 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 calcula ted where there are at least 10 sets of paired acute and chronic WET test data available. The ACR is dete rmined 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 TU a into TU c , 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.

Chapter 6: Water Quality-Based Effluent Limitations 6-37September 2010 NPDES Permit Writers’ Manual

Exhibit 6-21 Using the ACR
The ACR is expressed

25 50 IC LC Endpoint Chronic

Endpoint Acute ACR  
A TU is the inverse of the sample fraction. Therefore, by definition

25 c 50 a IC 100 TU LC 100 TU  
Consequently, toxicity as percent sample, may be ex pr essed

c 25 a 50 TU 100 IC TU 100 LC   Substituting into the original equation gives

a c

c a

25 50 TU TU

TU 100 TU 100

IC LC ACR 

Example 1 Given: LC 50 = 28%, IC 25 = 10%
8.2 10% 28% IC LC ACR

25 50  Example 2 Given: TU a = 3.6, TU c = 10.0
8.2 3.6 10.0 TU TU ACR

a c


LC 50 (% effluent) IC 25 (% effluent) ACR
62 10 6.2 18 10 1.8 68 25 2.7 61 10 6.1 63 25 2.5 70 25 2.8 17 5 3.4 35 10 3.5 35 10 3.5 35 25 1.4 47 10 4.7 Examp le 3 Given: Toxicity data for a facili ty’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:

25 50 IC LC ACR 
Mean 3.5 Example 4 Given: TU a = 1.8, ACR = 3.5

a c
a c TU x ACRTU TU TU ACR  

c a
a c a c TU 6.3TU 1.8x TU TU 3.5TU x ACR TU Estimated   



### 6.5.3 Determining the Need for WET Limitations 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 acc ounting for the applicable dilution allowance or mixing zone made available in the water quality standard s. The permit writer would compare the projected toxicity of the receiving water to the applicable wa ter quality criterion for WET. If the projected toxicity exceeds the applicable numeric water quality criteri on 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)(1)(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 co nduct a reasonable potential analysis for WET.

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Exhibit 6-22 Example of mass-balance equati on for a WET reasonable potential analysis

The mass-balance equation can be used to determine whet her the discharge from ABC Inc. would cause, have the reasonable potential to cause, or contribute to toxici ty in Pristine Creek that exceeds the numeric water quality criteria for acute or chronic toxicity. Assume the disch arge mixes rapidly and completely with Pristine Creek. Mass-Balance Equation: Q s C s + Q d C d = Q r C r Dividing both sides of the mass-balance equation by Q r gives the following:

r ssdd r Q ))(CQ())(C(Q C 



The following values are known for ABC Inc. and Pristine Creek: Q s = Critical upstream flow (1Q10 for acute protection) = 23.6 cfs (7Q10 for chronic protection) = 70.9 cfs C s = Upstream toxicity in Pristine Creek (acute) = 0 TU a (chronic) = 0 TU c Q d = Discharge flow = 7.06 cfs C d = Discharge toxicity (acute) = 2.50 TU a (chronic) = 8.00 TU c Q r

= Downstream flow = Q d + Q s Acute Water Quality Criterion in Pristine Creek = 0.3 TU a Chronic Water Quality Criterion in Pristine Creek = 1.0 TU c

Find the down s tream concentration (C r ) by inserting the given values into the equation as follows:
For acute toxicity:

a a a

r TU 58.0 cfs23.6cfs7.06 )TU 0)(cfs 6.23()TU cfs)(2.5 (7.06 C   



The downstream concentration (C r ) exceeds the water quality criter ion for acute toxicity of 0.3 TU a . For chronic toxicity:

c c c

r TU 72.0 cfs70.9cfs7.06 )TU 0)(cfs 9.70()TU cfs)(8.00 (7.06 C   



The downstream concentration (C r ) does not exceed the water quality criterion for chronic toxicity of 1.0 TU c .

In Exhibit 6-22 above, the downstream concentration under critical conditions for the acute water quality criterion (C r = 0.58 TU a ) exceeds the water quality criterion for acute toxicity (0.3 TU a ); 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 li mitations 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 b asis 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 s ituation, the permitting authority should have a policy for implementing the narrative criterion. Following th e 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)(1)(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 app licable 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, a ttainment 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)(1)(vi):

 Use EPA’s national recommended criteria.

 Calculate a numeric criterion that will attain a nd 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 effl uent toxicity problems, isolate the sources of that toxicity, identify and implement appropriate toxic ity 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 W ET 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 iden tify the cause of that toxicity or ways to reduce toxicity, a TIE/TRE is necessary to achieve compliance w ith 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 wr iter 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 concer n. The regulations concer ning 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 Ti er 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 water body is of high water qua lity for the parameters of concern, and thus will require Tier 2 protection. After identifying the tier(s) of protection for the

6-40 Chapter 6: Water Quality-Based Effluent LimitationsSeptember 2010 NPDES Permit Writers’ Manual

proposed receiving waterbody and parameter(s) of con cern, the permit writer should consult the state’s antidegradation implementation procedures relevant to the tier(s).
The following sections provide methods permit write rs should consider for implementing, through the WQBEL development process, the three levels of prot ection typically found in a state’s antidegradation policy. Implementation of the state’s antidegrada tion policy could have a significant effect on the calculation of WQBELs.



### 6.6.1 Tier 1 Implementation 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 pe rmit 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 ma king 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 pro cess varies among states, EPA’s antidegradation regulation at § 131.12 outlines the common elemen ts 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 im portant 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 satis faction of its own inter governmental coordination and public participation provisions.

 The state must assure that the highest statutor y and regulatory requirem ents for all new and existing point sources will be achieved.

 The state must assure that all cost-effective a nd reasonable BMPs for nonpoint source control will be achieved.

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6-42 Chapter 6: Water Quality-Based Effluent Limitations  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 protec tion, 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 increase d 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 ultimat ely resulting in restoration. Some states allow increased discharges as long as they are offset by eq uivalent 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 antidegrada tion requirements. Such waterbodies are sometimes referred to as Tier 2 1⁄2 waters because implementation of the an tidegradation 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, 199 8) include additional information on implementing antidegradation policies. The permit writer should clear ly explain the antidegradation analysis and how it affects calculation of WQBELs in the fact sh eet 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 Protecti on Agency, Office of Water, Washington DC.

< www.epa.gov/waterscienc e/standards/handbook/ >.

2 U.S. Environmental Protection Agency. 2001. Streamlined Water-Effect Ratio Pr ocedure for Discharges of Copper

. EPA-822-R-01-005. U.S. Environmental Protection Agency, Office of Scienc e and Technology, Washington, DC.

< www.epa.gov/waterscience/cr iteria/copper /copper.pdf >.

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.

< www.epa.gov/waterscience/library /wqcriteria/n aturalback.pdf >

. 4 U.S. Environmental Protection Agency. 1991. Technical Support Document for Water Quality-Based Toxics Control (TSD). EPA-505/2-90-001. U.S. Environmen tal Protection Agency, Office of Water, Washington, DC.

< www.epa.gov/npdes/pubs/owm0264.pdf >.

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.

< www.epa.gov/bioindicato rs/html/biolcont.html >.September 2010 NPDES Permit Writers’ Manual

Chapter 7: Final Effluent Limitations and Anti-backsliding 7-1 

## 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 th e 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 effl uent limitations are consistent with the Clean Water Act (CWA) requirements and NPDES regulations related to anti-backsliding.

Exhibit 7-1 Developing effluent limitations



## 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 a nd water quality standards, are fully implemented.

 The permit writer determines the calculated limita tions (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 pe rmit, the permit writer then conducts an antibacksliding 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.September 2010 NPDES Permit Writers’ Manual

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, wh ere appropriate, how an an ti-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 e ffluent limitations for a pollutant that ensure that all CWA standards are met, the permit writer appli es 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, rei ssuance, 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 familiarit y 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 prohib its 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 Prohibi tion Against Backsliding First, CWA section 402(o)(1) 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 promulgate d effluent limitations guidelines and standards (effluent guidelines) that would result in a less stringent effluent limitation.

 Relaxation of an effluent lim itation that is based on state standards, such as water quality standards or treatment standards, unless the cha nge 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 limita tions is subject to the exceptions in CWA section 402(o)(2) and, for limitations based on state standard s, 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 th e 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 alterna tions or additions to the permitted facility that justify the relaxation.

7-2 Chapter 7: Final Effluent Limitations and Anti-backslidingSeptember 2010 NPDES Permit Writers’ Manual

 New information (other than revised regulations, gu idance, 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)(1)(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), or 316(a).

 The permittee has installed and pr operly operated and maintained required treatment facilities but still has been unable to meet the effluent limit ations (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)(1) 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 sec tion 402(o)(2) is met. The two provisions constitute independent exceptions to the prohibition against rela xation 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 ba sed 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)(1) may be relaxed, the exceptions for technical mistakes or mistaken interpretations and permit modi fication, which are described above, would not apply to WQBELs.

Chapter 7: Final Effluent Limitations and Anti-backsliding 7-3September 2010 NPDES Permit Writers’ Manual



### 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 limit ations in all cases if the revised effluent limitation would result in a violation of applicable efflue nt 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 w ith 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(l). The regulations do not specifically address backslidi ng 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)(1)(C), 303(d) or 303(e)]. They do, however, address all other forms of backsliding.
First, the regulations at § 122.44(l)(1) restrict the relaxation of final effluent limitations and the relaxation of standards or conditions contained in existing permits. Thus, th is regulation, in effect, addresses all types of backsliding not addressed in the CWA provi sions (e.g., backsliding from limitations derived from effluent guidelines, from new source performan ce standards, from existing case-by-case limitations to new case-by-case limitations, and from conditions su ch 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 relaxa tion 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 seek s to revise an existing case-by-case TBEL developedusing BPJ to reflect a subsequently promulgated effluent guideline that is less stringent than the case-bycase requirement. The regulations include the same exce ptions 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 re laxation is either a case-by-case effluent limitation developed using BPJ or is any other limitation, sta ndard, or condition other th an an effluent limitation based on a state standard, the permit writer can a pply the requirements in § 122.44(l). 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-backsliding requirements

Exhibit 7-3 presents some exa mples 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 fo r 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, WQBE Ls 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 se ction 402(o)(2) restricts the use of new information to cases where there is a decrease in t he amount of pollutants being discharged. The CWA section 402(o)(1) exceptions, on the other hand, mi ght justify the request. In th is 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 stand ards, permit limitations based on a TMDL or other WLA or other permit standard may be rela xed if the state's antidegradation policy requirements are met. Example 2

 The state has established a techno logy-based treatment standard for feca l coliform pursuant to CWA section 301(b)(1)(C).

 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 limitat ion 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 wa s 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 provisi on 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 technol ogy-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 se ction of the CWA, new information does not include revised regulations

.

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Chapter 7: Final Effluent Limitations and Anti-backsliding 7-7 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 water—specifically 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 (inc luding 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 limitat ion 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 CW A 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 demon strate 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 ot her potential sources of toxicity in the future. Example 4

 An industrial permittee seeks to re vise 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. T he ambient concentration of TSS exceeds the applicable water quality criteria.

 An effluent limitation of 100 mg/L is cons istent 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).September 2010 NPDES Permit Writers’ Manual

Chapter 8: Monitoring and Reporting Conditions 8-1 

## 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 app licable) 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 complia nce 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 c onsiderations 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 li mitations established in thei r 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 dete rminations. Factors that could affect sampling location, sampling method, and sampling frequency include the following:

 Applicability of effluent limitations guide lines and standards (effluent guidelines).

 Wastestream and process variability.

 Access to sample locations.

 Pollutants discharged.

 Effluent limitations.

 Discharge frequencies (e.g., con tinuous versus intermittent).

 Effect of flow or pollutant load or both on the receiving water.

 Characteristics of the pollutants discharged.

 Permittee’s compliance history.September 2010 NPDES Permit Writers’ Manual



### 8.1.1 Purposes of Monitoring Monitoring is performed to determine complian ce with effluent limitations established in NPDES permits, establish a basis for enforcement actions, asse ss 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 othe r 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 al so specify the monitoring type, intervals, and frequency sufficient to yield data that are representa tive 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 mon itoring 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 regula tions do not prescribe exact monitoring locations; rather, the permit writer is responsib le for determining the most appr opriate 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 represent ative of the discharge [§ 122.41(j)(1)].
The permit writer should consider the following qu estions when selecting a monitoring location:

 Is the monitoring location on the facility’s property?

 Is the monitoring location accessible to th e 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 wher e the wastewater is well mixed, such as near a Parshall flume or at a location in a sewer with hydr aulic 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 sample d at the Parshall flume before the discharge point for Outfall 002. 3. Discharge from the Research Lab No. 1 must be samp led at the Parshall flume before the discharge point for Outfall 003.
Diagram A. Monitoring Locations

Outfall Description

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.

Final pH Adjustment Tank * Sample Point * Parshall Flume
Receiving Stream
Outfall

001

The monitoring location will vary depending on the ty pe of m onitoring required. The following sections discuss monitoring location considera tions for each monitoring type.



### 8.1.2.1 Influent and source water monitoring locations 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 (BOD 5 ) 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 wa ter before use as process water (e.g., river water used as contact cooling water). The permit writer shoul d 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 write r 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. Intern al 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 in ternal 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 th e process wastewater is combined with nonprocess wastewater.

 Ensuring compliance with secondary t reatment 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 ab ility to accurately monitor for compliance with secondary treatment standards. Under such circ umstances, the permit writer could consider requiring monitoring for compliance with limitati ons derived from secondary treatment standards before such processes. For example, the permit c ould 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 pollu tant of concern such that it would not be detectable using approved analytical methods. In ternal 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 applica tion of limitations at those locations.



### 8.1.2.3 Effluent monitoring locations Effluent monitoring is monitoring of the final efflue nt after all treatment processes. The permit writer should require effluent monitoring to determine comp liance 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 wher e 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 partic ularly true for ensuring compliance with WQBELs.



### 8.1.3 Monitoring Frequency The permit writer should establish m onitoring 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 fo r 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 di scharge that is relatively consistent over time (particularly in terms of flow and pollutant concentra tion). 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 near ing 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 employ ing 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 w ith problems achieving compliance generally should be required to perform more frequent mon itoring 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 continu ous discharge of highly concentrated wastewater or a wastewater containing a pollutant that is f ound infrequently and at very low concentrations. The production schedule of the facility (e.g., seasona l, 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 cons ider the number of monthly samples used in developing average monthly WQBELs. If the di scharger monitors less frequently than the monthly monitoring frequency assumed when deve loping applicable effluent guidelines or in calculating a WQBEL, it could be more difficult fo r 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 dischar ger 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 include d 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 me tals and pH can provide information for both compliance assessment and determination of treatment efficacy.
A permit writer could also establish a tiered monitori ng schedule that reduces or increases the monitoring frequency during a permit cycle. Tiered monitoring mi ght be appropriate for discharges where the initial sampling shows compliance with effluent limitations, ju stifying a reduction in monitoring frequency over time. Conversely, if problems are found during the in itial 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 th e data needed to demonstrate compliance with effluent limitations.

In 1996 EPA issued Interim Guidance for Performance-Based Reductions of NPDES Permit M onitoring Frequencies < www.epa.gov/npdes/pubs/perf-red.pdf >. Under the guidance, NPDES reporting and monitoring requirements may be reduced on the basis of a dem onstration of excellent historical performance. Facilities can demonstrate that historical performan ce by meeting a set of compliance and enforcement criteria and by demonstrating their ab ility to consistently discharge po llutants below the levels necessary to meet their existing NPDES permit limitations. Re ductions are determined pa rameter-by-parameter, on the basis of the existing monitoring frequency an d the percentage below the limitation at which the parameter is being discharged. The reductions are in corporated 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 Manual 1

< www.epa.gov/compliance/resources/publ ications/monitoring/cw a/inspections/npdesins pect/npdesmanual.html >.



### 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 sa mpled 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 concen trations 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 usef ul 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 disch arge 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 concentra tion 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 m onitoring 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 co mposited 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: constantvolume when the interval time varies between samp les, or constant-time when the interval volume collected varies between samples as shown in Exhibit 8-3.

Exhibit 8-3 Visual interpretation of flow-proportional composite monitoring

The constant-volume, flow-proportional, composite monitoring method collects a constant sample volume at varying time intervals proportional to str eam 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 th e 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 coll ection. The permit writer should also establish the time frame within which the sample is to be coll ected and the number of individual aliquots in the composite.

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There are instances where composite samples are in appropriate. For example, the permit application regulations at § 122.21(g)(7) indicate that grab sampl es 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. Seque ntial 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 eith er time or effluent flow. Unlike a combined composite sampler, the sequential sampling device au tomatically 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 co mbining 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, accur acy, and cost of continuous monitoring vary with the parameter monitored. The permit writer shoul d 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 Re quirements 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 pe rmits 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 frequenc y of monitoring is based on the annual amount of sewage sludge that is used or disposed of by th ose methods. POTWs that provide the sewage sludge to another party for further treatment (such as composti ng) must provide that party with the information necessary to comply with regulations at Part 503. Se wage sludge disposed of in a municipal solid waste landfill unit must meet the criteria for municipal soli d waste landfills in the regulations at Part 258.

Chapter 8: Monitoring and Reporting Conditions 8-9September 2010 NPDES Permit Writers’ Manual

Exhibit 8-4 shows the minimum monitoring require ments established in Part 503 for sewage sludge before use and disposal. More frequent monitoring fo r 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

 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 Surface disposal: lined sites with leachate collection and unlined sites

 Methane gas  Continuously § 503.26

 Sludge weight and percent total solids

 Metals: As, Cd, Cr, Pb, and Ni 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)

 THC or O 2 , moisture, combustion temperatures  Continuously Incineration

 Air pollution control device operating parameters  As required by permitting authority § 503.46

Notes: Monitoring frequencies required by Part 503 may be reduced afte r 2 years of monitoring, but in no case may be less than once per year. A successful land application program could necessitate sampli ng for other constituents of c oncern (such as nitrogen) in determining appropriate agronomic rates. The permit wr iter 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 Guidance 2 < www.epa.gov/npdes/pubs/owm0237.pdf >.

 POTW Sludge Sampling and Analysis Guidance Document 3 < www.epa.gov/npdes/pubs/owm012.pdf >.

 Control of Pathogens and Vector Attraction in Sewage Sludge 4

< www.epa.gov/ORD/NRMRL /pubs/625r92013/625r92013.htm >.



### 8.2.2 Combined Sewer Overflows (CSOs) and Sanitary Sewe r Overflows (SSOs) EPA’s Combined Sewer Overflow (CSO) Control Policy (59 FR 18688, April 19, 1994) requires monitoring to characterize the combined sewer syst em, assist in developing a Long-Term Control Plan (LTCP), and show compliance with permit requirement s. 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 co nduct 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: Gui dance for M onitoring and Modeling 5

< www.epa.gov/npdes/pubs/sewer.pdf >.
A facility’s permit might also contain monitoring re quirements for sanitary sewer overflows (SSOs). SSO monitoring requirements would be developed on a case-by-case basis.



### 8.2.3 Stormwater Monitoring Considerations Stormwater monitoring requirements vary according to the type of permit regulating the stormwater discharge and the activity. Municipal separate stor m 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 qua lity monitoring as a condition in their NPDES general permit, though evaluation of measurab le goals may include monitoring. EPA’s multi-sector general permit (MSGP) for stormwater discharges from industrial fac ilities includes analytical monitoring requirements based on the type of industrial activity. Finally, ope rators of construction activity regulated under the

Chapter 8: Monitoring and Reporting Conditions 8-11September 2010 NPDES Permit Writers’ Manual

construction general permit are typically not require d to conduct water quality monitoring; however, some states and EPA Regions do require monitoring if th e 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 < www.epa.gov/npdes/stormwater >). Additional documents on stormwater monitoring are:

 Urban Stormwater BMP Performance: A Guidance Manual for Meeting the National Stormwater BMP Database Requirements 6 < www.epa.gov/npdes/pubs/montcomplete.pdf >.

 Guidance Manual for the Monitoring and Reporting Requirements of the NPDES Stormwater Multi-Sector General Permit (MSGP) 7 < www.epa.gov/npdes/pubs/dmr-fin.pdf >.



### 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 < www.epa.gov/npdes/wet >. 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. W ET 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 < www.epa.gov/waterscience/WET/disk2/atx.pdf >.

 Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms . 4th ed. 9 < www.epa.gov/waterscien ce/WET/disk3/ctf.pdf >.

 Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Marine and Estuarine Organisms . 3rd ed. 10 < www.epa.gov/waterscien ce/WET/disk1/ctm.pdf >.

 NPDES Compliance Monitoring Inspector Training: Biomonitoring 11 (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 ex ceeds the composite sampler volume.
WET tests are relatively expensive compared to singl e parameter tests. Theref ore, a permit writer should carefully consider the appropriate frequency for WET t esting. 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 perm it writer should consider when establishing appropriate WET monitoring frequencies include the following:

 Type of treatment process.

8-12 Chapter 8: Monitoring and Reporting ConditionsSeptember 2010 NPDES Permit Writers’ Manual

 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 < www.epa.gov/waterscience/methods/ > 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 < www.epa.gov/waterscien ce/methods/basic.htm >. 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 pr ocedures 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 )

< www.nemi.gov/ >. 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, spikin g level, instrumentation, lab equipment, and the
greenness of analytic methods. Permit writers might fi nd that information useful in comparing the features of Part 136 methods that will be used fo r assessing compliance with the calculated effluent limitations.
When establishing effluent limitations for a specifi c parameter (based on technology or water quality regulatory requirements), it is possible for the valu e 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 av ailable to detect and quantify the parameter at the concentration of the calculated limitation, the limita tion must be included in the permit as calculated.
In some instances, there might be two or more appr oved Part 136 analytical methods available for the analysis of a parameter. In such cases, the permit s hould 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 cont ains 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) Permits 12

< www.epa.gov/npdes/pubs/mercuryme mo_analyticalmethods.pdf >.

Chapter 8: Monitoring and Reporting Conditions 8-13September 2010 NPDES Permit Writers’ Manual

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 sensit ive 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, s ee 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

< www.epa.gov/npdes/pubs/dmr.pdf >. Data reported include both data re quired 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 monito ring 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 extensi on 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 ch art 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 monito ring parameters not regulated by the Part 503 rule.

8-14 Chapter 8: Monitoring and Reporting ConditionsSeptember 2010 NPDES Permit Writers’ Manual

Chapter 8: Monitoring and Reporting Conditions 8-15 1 U.S. Environmental Protection Agency. 2004. NPDES Compliance Inspection Manual . EPA-305-X-03-001. U.S. Environmental Protection Agency, Office of Enfor cement and Compliance Assu rance, Washington, DC.

< www.epa.gov/compliance/resources/publ ications/monitoring/cw a/inspections/npdesins pect/npdesinspect.pdf >.

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. < www.epa.gov/npdes/pubs/owm0237.pdf >.

3 U.S. Environmental Protection Agency. 1989. POTW Sludge Sampling and Analysis Guidance Document . EPA-833-B-89-100. U.S. Environmental Protection Agency, Office of Water, Washington, DC. < www.epa.gov/npdes/pubs/owm012.pdf >.

4 U.S. Environmental Protection Agency. 1992. Control of Pathogens and Vector Attraction in Sewage Sludge . EPA-625/R-92- 013. U.S. Environmental Protecti on Agency, Office of Research a nd Development, Washington, DC.

< www.epa.gov/ORD/NRMRL/ pubs/625r92013/625r92013.htm >.

5 U.S. Environmental Protection Agency. 1999. Combined Sewer Overflows–Gui dance for Monitoring and Modeling . EPA-832- B-99-002. U.S. Environmental Protection Agen cy, Office of Water, Washington, DC. < www.epa.gov/npdes/pubs/sewer.pdf >.

6 U.S. Environmental Protection Agency. 2002. Urban Stormwater 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. < www.epa.gov/npdes/pubs/montcomplete.pdf >.

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 Prot ection Agency, Office of Water, NPDES Program Branch, Washington, DC. < www.epa.gov/npdes/pubs/dmr-fin.pdf >.

8 U.S. Environmental Protection Agency. 2002. Methods for Measuring the Acute Toxici ty 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 < www.epa.gov/waterscience/WET/disk2/atx.pdf >.

9 U.S. Environmental Protection Agency. 2002. Short-Term Methods for Estimating th e Chronic Toxicity of Effluents and Receiving Waters to Freshwat er Organisms, Fourth Edition . EPA-821-R-02-013. U.S. Environmen tal Protection Agency, Office of Water, Washington, DC. < www.epa.gov/waterscien ce/WET/disk3/ctf.pdf >.

10 U.S. Environmental Protection Agency. 1994. Short-Term Methods for Estimating th e Chronic Toxicity of Effluents and Receiving Waters to Marine and Es tuarine Organisms, Third Edition . EPA821-R-02-014. U.S. Environmental Protection Agency, Office of Wate r, Washington, DC. < www.epa.gov/waterscience/WET/disk1/ctm.pdf >.

11 U.S. Environmental Protection Agency. 1990. NPDES Compliance Monitoring Inspector Training: Biomonitoring

. U.S. Environmental Protection Agency, O ffice of Water Enforcement and Permit s, Washington, DC. NTIS # PB91-145854. (No Link)

12 Hanlon, James A. 2007. Analytical Methods for Mercury in National Po llutant Discharge Elimin ation System (NPDES) Permits. U.S. Environmental Protection Agency, Office of Wastewater Management. Memo randum, August 23, 2007.

< www.epa.gov/npdes/pubs/mercury memo_analy ticalmethods.pdf >.September 2010 NPDES Permit Writers’ Manual

Chapter 9: Special Conditions 9-1 

## CHAPTER 9. Special Conditions

Special conditions in National Pollutant Discharge Elimination System (N PDES) permits supplement numeric effluent limitations and require the perm ittee 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 incorporat e special conditions into a permit including:

 To address unique situations, such as facilities disch arging 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 am bient stream surveys, toxicity identification evaluations (TIEs) and toxicity reduction evaluations (TREs), bioaccumulation studies, sediment studies, mixing or mixing zone studies, pollu tant reduction evaluations, or other such information-gathering studies.
Section 9.1 below addresses several types of special conditions that apply to both municipal and nonmunicipal 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:

 A dditional monitoring and special studies.

 B est management practices (BMPs).

 C ompliance schedules.September 2010 NPDES Permit Writers’ Manual

A summary of the use of those special conditions follows.



### 9.1.1 Additional Monitoring and Special Studies Additional monitoring requirements, beyond those re quired under the effluent limitations section of the permit, and special studies are useful for collecting da ta that were not available to the permit writer for consideration during permit deve lopment. Additional monitoring requirements and special studies generally are used to supplement numeric effluent limitations or support fu ture 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 developi ng 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/toxi city 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 evalua tions 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 Plants 1

< www.epa.gov/npdes/pubs/tre.pdf >.

− Clarifications Regarding Toxicity Reduction and Identification Evaluations in the National Pollutant Discharge Elimination System Program 2 < www.epa.gov/npdes/pubs /owmfinaltretie.pdf >.

− Generalized Methodology for Conducting Indu strial Toxicity Reduction Evaluations 3 ( No link— see the endnote for ordering instructions ).

− Methods for Aquatic Toxicity Identification Ev aluations: Phase I Toxicity Characterization Procedures . 2nd ed 4 < www.epa.gov/npdes/pubs/owm0330.pdf >.

− Toxicity Identification Evaluation: Characteriza tion of Chronically Toxic Effluents, Phase I 5

< www.epa.gov/npdes/pubs/owm0255.pdf >.

− Methods for Aquatic Toxicity Identification Evaluations: Phase II Toxicity Identification Procedures for Samples Exhibiting Acute and Chronic Toxicity 6

< www.epa.gov/npdes/pubs/owm0343.pdf >.

− Methods for Aquatic Toxicity Identification Evaluations: Phase III Confirmation Procedures for Samples Exhibiting Acute and Chronic Toxicity 7 < www.epa.gov/npdes/pubs/owm0341.pdf >.

 Mixing or mixing zone studies: Might be required in a permit to assist in determining how effluent and receiving water mix and in establishi ng 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 qualit y criteria are expressed in terms of fish tissue levels. Additional guidance relate d to evaluating the bioaccumulation potential of a pollutant can

9-2 Chapter 9: Special ConditionsSeptember 2010 NPDES Permit Writers’ Manual

be found in the EPA Great Lakes Water Quality Initiative Technical Support Document for the Procedure to Determine Bioaccumulation Factors 8 ( No link—see 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 storag e 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 requi re 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 disch arges from municipal storm sewers must require controls, including management practices, to reduce the discharge of pollutants. Finally, CWA sections 402(a)(1) 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 stat utory 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 limitati ons 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 BMPs 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 indivi dual permit where a permit writer has the opportunity to review the circumstances at the facility. On the ot her 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 particul ar 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 comp liance 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 pr evention 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.

9-4 Chapter 9: Special ConditionsSeptember 2010 NPDES Permit Writers’ Manual

BMP Plans

The Guidance Manual for Developing Best Management Practices 9 < www.epa.gov/npdes/pubs/owm0274.pdf > 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 fac ility’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 fo r developing the BMP plan and assisting the plant management in implementing and updating the BMP plan.
EPA has identified several recommended component s 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 objective.

− 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 ag ency or be kept on-site and made available to the permitting authority upon request. A general schedule fo r BMP plan development can be included in the permit (e.g., complete and submit the plan within si x months of permit issuance and begin implementing the plan within nine months of permit issuance).
Exhibit 9-1 presents example permit text for a requi rement 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 mana gement 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 mu st update and amend the plan as needed. [IF A BMP PLAN ALREADY EXISTS:] The permittee must during the term of this permit operat e the facility in accordance with the BMP plan [CITE EXISTING PLAN] and in accordance with subsequent am endments to the plan. The permittee must amend the plan to incorporate practices to achieve the object ives and specific requirements listed below, and a copy of the amended plan must be submitted to t he 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 mont hs from the effective date of the permit. 2. Purpose Through implementation of the BMP pl an the permittee must prevent or minimize the generation and the potential for the release of pollutants from the facilit y to the waters of the Un ited States through normal operations and ancillary activities. 3. Objectives The permittee must develop and amend the BMP plan consist ent with the following objectives for the control of pollutants.
a. The number and quantity of pollut ants and the toxicity of effluent ge nerated, discharged, or potentially discharged at the facility must be minimized by th e permittee to the extent feasible by managing each influent waste stream in the most appropriate manner. b. Under the BMP plan, and any St andard Operating Procedures (SOPs) included in the plan, the permittee must ensure proper operation and maintenance of t he treatment facility as required by § 122.41(e).
c. The permittee must establish specif ic objectives for the control of pollutants by conducting the following evaluations. 1. Each facility component or system must be exam ined 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 operat ions 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 potentia l for equipment failure (e.g., a tank overflow or leakage), natural condition (e.g., precipitation), or ot her 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 pollut ants that could be discharged from the facility as a result of each condit ion or circumstance. 4. Requirements The BMP Plan must be consistent wi th the objectives in the Object ives section above and the general guidance contained in the publication entitled Guidance Manual for Developing Best Management Practices (BMPs) , EPA 833-B-93-004, < www.epa.gov/npdes/pubs/owm0274.pdf > or any subsequent revisions to the guidance document. The BMP plan must
a. Be documented in narrative form, must include an y 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 pr ocedures of the BMP Committee. 4. Specific management practices and standard operat ing 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 contro l, 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 t he 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 certif ication of the reviews.
c. Establish specific BMPs to meet the objectives i dentified 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 foll owing 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, Cont rol, 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 IN SPECTIONS, 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 t he 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 ob jective 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 pr actices. Traditionally, BMPs have focused on good housekeeping measures and good management techni ques that attempt to avoid contact between pollutants and water as a result of leaks, spills, and im proper 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 subs titution, and materials and water conservation.
When developing BMPs, permit writers should be familiar with the f undamental 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 h as 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 pollu tion prevention practices are necessary to carry out the purposes and intent of the CWA, the permit write r may develop BMPs to implement those practices.



### 9.1.3 Compliance Schedules The NPDES regulations at § 122.47 allow permit wr iters 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 di schargers. 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 cond itions (i.e., provides for up to a 90-day period to achieve compliance).
Examples of requirements for which a compliance sc hedule 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 addr esses compliance schedules for effluent limitations derived from new or revised water qua lity standards. In the decision In the Matter of Star-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

< www.epa.gov/npdes/pubs/owm0121.pdf >, the EPA Administrator interpreted CWA section 301(b)(1)(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 st andards 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 E ffluent Limitations in NPDES Permits 11

< www.epa.gov/npdes/pubs/memo_comp lianceschedules_may07.pdf >. 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 enforceable final 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 appr opriate 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 an d, 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 co mpliance is required as soon as possible include the steps needed to modify or install treatment f acilities, operations, or other measures and the time those steps would take.

 Include an enforceable sequence of events lead ing 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 an alysis (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 ow ned treatment works (POTWs) to implement and enforce local pretreatment programs for their indus trial 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) esta blish 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 PO TW 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 industria l 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, incl uding interference with the use or disposal of municipal sludge.

 To improve opportunities to recycle and reclaim m unicipal and industrial wastewater and sludges.
The pretreatment program also helps en sure 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 PO TW's NPDES permit. NPDES permits drive the development and implementation of pretreatme nt 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 progr am that meets the requirements in § 403.9(b). A more detailed description of these required program elem ents 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 appli cable pretreatment standards and requirements. These control mechanisms must have certain conditions as laid out in § 403.8(f)(1)(iii) and be enforceable.

 Require the development of compliance schedules wh ere necessary by each industrial user for the installation of technology required to meet appli cable pretreatment standards and requirements, and submission of all notices and self-monitori ng reports to assess and ensure compliance.

 Carry out all inspection, surveillance, and monitoring procedures necessary to determine compliance with applicable pretreatment standa rds and requirements independent of information submitted by the industrial user (including the au thority 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 pretreat ment 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 surve illance activities to determine compliance with applicable pretreatment standards and requireme nts independent of information supplied by the industrial user.

 Investigate instances of noncompliance.

 Comply with public participation requirements, in cluding annual public notice of industrial users determined to be in significant noncomp liance during the previous 12-month period.
Also, as part of the POTW pretreatment program, PO TWs 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. Th e 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 appr oval as stated in § 403.8(b). Once the permitting authority reviews and approves the program, the requi rement 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 ordi nance, 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 modi fication, 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 pr ogram 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 deve lopment or implementati on conditions (with minor modifications made to tailor the conditions to the sp ecific 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 pretreat ment coordinators. The permit writer might need to update or modify pretreatment im plementation language or initiate corrective action related to the pretreatment program.
EPA has developed the Pretreatment Program Website < www.epa.gov/npdes/ pretreatment > and prepared a number of guidance manuals for POTWs on how to impl ement their local pretreatment programs that are accessible through this website. In addition, EPA prepared the Introduction to the National Pretreatment Program 12 < www.epa.gov/npdes/pubs/final99.pdf > 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 identif ying possible modifications to the pretreatment program’s local limits or procedures, or the n eed for water quality-based controls. The permit writer should obtain such data with the aid of the pretreat ment coordinator. Permits must include conditions requiring a POTW to provide a written technical ev aluation of the need to revise local limits under § 403.5(c)(1) 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 w ith an approved pretreatment program or required to develop a pretreatment program must sample and anal yze 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 u se and disposal of sewage sludge to protect public health and the environment from any reasonably anti cipated adverse effects of these practices. In the CWA, Congress directed EPA to develop technical st andards 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 c onstruction 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 muni cipal solid waste landfill. The standards for each end use and disposal method consist of general requi rements, numeric effluent limitations, operational standards, and management practices, as well as moni toring, 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 ba sed 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 Rule 13

< www.epa.gov/owm/mtb/biosolids/503pe/ >.
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 revi ew and comment. The risk assessment evaluated and established limitations for a number of pollutant s. These limitations are in chapter 4 of A Guide to the Biosolids Risk Assessments for the EPA Part 503 Rule 14 < www.epa.gov/owm/mtb/ biosolids/503rule/ >.
The regulation is largely self-implementing, and anyone who engages in activities covered by the regulation must comply with the appropriate requi rements 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 sl udge use or disposal requirements in any NPDES permit issued to a Treatment Works Treating Domest ic 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 NPD ES permits and NPDES permit issuance to treatment works that do not have an effluent discharge to wa ters of the United States, but are involved in sewage sludge use or disposal as preparers, appliers, or owners/operators. TWTDS in cludes all sewage sludge generators and facilities, such as blenders , that change the quality of sewage sludge.
EPA recognizes that implementation of Part 503 requirem ents 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 Guidance 15 < www.epa.gov/npdes/pubs/owm0237.pdf >.

 Land Application of Sewage Sludge—A Guide for Land Appliers on the Requirements of the Federal Standards for the Use or Disposal of Sewage Sludge Management in 40 CFR Part 503 16

< www.epa.gov/npdes/pubs/sludge.pdf >.

 Surface Disposal of Sewage Sludge—A Guid e 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 503 17 < No Link–see the endnote for ordering instructions >.

 Preparing Sewage Sludge for L and Application or Surface Disposal—A 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 503 18 < No Link–see the endnote for ordering instructions >.

 Domestic Septage Regulatory Guidance, A Guide to the EPA 503 Rule 19

< www.epa.gov/npdes/pubs/owm0026.pdf >.

 Control of Pathogens and Vector Attraction in Sewage Sludge 20

< www.epa.gov/nrmrl/pubs/625r92013/625R92013.pdf >.
The permit writer should refer to the Part 503 Implementation Guidance and EPA Region and state guidelines or policies for instructions on how to impl ement 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 v ector attraction reduction requirements for land application and surface disposal and total hydro carbons (THC) concentrations for incinerators).

 Management practices (e.g., siting restricti ons, 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., cont ents of reports and frequency or due dates for submission of reports).

 General requirements (e.g., specific notification re quirements before land application, submission of closure and post closure plan for surface disposal sites).
In addition to any specific applicable Part 503 standa rds, 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 di sposal practice occurs (or is planned) [see standard conditions in § 122.41(l)(1)(iii)].
If permit conditions based on existing regulations ar e insufficient to protect public health and the environment from adverse effects that could occur from toxic pollutants in sewage sludge, permit conditions should be devel oped 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 adve rse 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 < www.epa.gov/owm/mtb/biosolids/index.htm >



### 9.2.3 Combined Sewer Overflows (CSOs) Combined sewer systems were designed and built in the 19 th and early 20 th 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 overfl ow 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 18 688, 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 co mprehensive and coordinate d planning effort to achieve cost-effective CSO controls that ultimately m eet 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 C ontrol 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 non conventional and toxic pollutants and Best Conventional Technology (BCT) for conventional polluta nts. 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 recomme nded approach for developing and issuing NPDES permits to control CSOs. In addition, EPA has deve loped the following CSO guidance documents to help permit writers and permittees implement the CSO Control Policy:

 Combined Sewer Overflows–Guidance for Long-Term Control Plan 21

< www.epa.gov/npdes/pubs/owm0272.pdf >.

 Combined Sewer Overflows–Guidance for Nine Minimum Controls 22

< www.epa.gov/npdes/pubs/owm0030.pdf >.

 Combined Sewer Overflows–Guidance for Screening and Ranking 23 < www.epa.gov/npdes/cso >.

 Combined Sewer Overflows–Guidance for Monitoring and Modeling 24

< www.epa.gov/npdes/pubs/sewer.pdf >.

 Combined Sewer Overflows–Guidance for Financial Capability Assessment and Schedule Development 25 < www.epa.gov/npdes/pubs/csofc.pdf >.

 Combined Sewer Overflows–Guidance for Funding Options 26

< www.epa.gov/npdes/pubs/owm0249.pdf >.

 Combined Sewer Overflows–Guidance for Permit Writers 27 < www.epa.gov/npdes/cso >.

 Combined Sewer Overflows–Guidance: Coordi nating Combined Sewer Overflow Long-Term Planning with Water Quality Standards Reviews 28 < www.epa.gov/npdes/pubs/w qs_guide_final.pdf >.
Combined Sewer Overflows–Guidance for Permit Writers 24 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 guidan ce 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.

9-16 Chapter 9: Special ConditionsSeptember 2010 NPDES Permit Writers’ Manual

Exhibit 9-2 Categories of CSO permitting conditions NPDES permit Phase I Phase II Post phase II A. Technology-based  NMC, at a minimum  NMC, at a minimum  NMC, at a minimum B. Water Quality-based  Narrative  Narrative + performancebased standards  Narrative + performancebased standards + numeric WQBELs (as appropriate) C. Monitoring  Characterization, monitoring, and modeling of CSS  Monitoring to evaluate water quality impacts

 Monitoring to determine effectiveness of CSO controls  Post-construction compliance monitoring

D. Reporting  Documentation of NMC implementation

 Interim LTCP deliverables  Implementation of CSO controls (both NMC and long-term controls)  Report results of postconstruction compliance monitoring

E. Special conditions  Prohibition of dry weather overflows (DWO)

 Development of LTCP  Prohibition of DWO

 Implementation of LTCP

 Reopener clause for water quality standards violations

 Sensitive area reassessment  Prohibition of DWO

 Reopener clause for water quality standards violations

Depending on the permittee’s situation, a permit ma y contain both Phase I and Phase II elements. Phase I permits require demonstration of implementa tion 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 colle ction system for storage 3. Review and modification of pr etreatment requirements to ensur e 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 pollu tion prevention programs

8. Public notification to ensure that the public receives adequate not ification of CSO occurrences and CSO impacts 9. Monitoring to effectively characterize CS O 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 mi nimum includes the NMC, as determined on a BPJ basis by the permitting authority.

 Develop and submit a report documenting the impl ementation of the NMC within 2 years of permit issuance/modification.

Chapter 9: Special Conditions 9-17September 2010 NPDES Permit Writers’ Manual

 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 infl uence 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 im plemented, operated and maintained as described in the LTCP.

 Water quality-based effluent limits under §§ 122. 44(d)(1) and 122.44(k), requiring, at a minimum, compliance with, no later than th e 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 sew age by volume for treatment under specified design conditions consistent with II.C.4.a.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 establishe d schedule, the approved post-construction water quality assessment program including requirements to monitor and collect sufficient information to demonstrate compliance with water quality st andards 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 physica lly possible and economically achievable.

 Conditions establishing requirements for maximizi ng 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 aut hority to reopen and modify the permit upon determination that the CSO controls fail to me et 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 ge nerally are expressed as narrative requirements and performance standards for the combined sewer syst em. 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 WQ BELs when there are sufficient data to support their development.
LTCP implementation schedules were expected to incl ude project milestones and a financing plan for design and construction of necessary controls as s oon as practicable. The CSO Control Policy expected permitting authorities to undertake the following:

 Review and revise, as appropriate, state CSO pe rmitting strategies developed in response to the National CSO Control Strategy.

 Develop and issue permits requiring CSO commun ities to immediately implement the NMC and document their implementation and develop and implement an LTCP.

 Promote coordination among the CSO community, th e water quality standards authority, and the general public through LTCP de velopment and implementation.

 Evaluate water pollution control needs on a waters hed basis and coordinate CSO control with the control of other point and nonpoint sources of pollution.

 Recognize that it might be difficult for some sma ll 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 fo r waterbodies that receive CSO discharges. The CSO Control Policy recognized that substantial coordi nation 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 technol ogy-based requirements and applicable state water quality standards, the permit writer, in conjunction w ith staff involved in water quality standards and the

Chapter 9: Special Conditions 9-19September 2010 NPDES Permit Writers’ Manual

permittee, should identify the appropriate site-speci fic considerations that will determine the CSO conditions to be established in the permit. EPA believes that the following information will be particularly relevant in devel oping 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 impact s 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, includi ng 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 secti on 2.3.1.4 of this manual and the Combined Sewer Overflows Website < www.epa.gov/npdes/cso >.



### 9.2.4 Sanitary Sewer Overflows (SSOs)

EPA’s Report to Congress on the Impacts and Control of CSOs and SSOs 29

< www.epa.gov/npdes/csossoreport2004 > shows that NPDES permit requireme nts establishing clear reporting, recordkeeping and third party notification of ove rflows from municipal sewage collection systems, as well as clear requirements to properly operate and mainta in 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 sta ndard conditions that are to be in NPDES permits for POTWs as discussed in Chapter 10 of this manual. Standard cond itions in a permit for a POTW apply to portions of the collection system for which the permittee has owne rship or has operational control. When reissued, permits for POTW discharges should clarify how key standard permit conditio ns 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

< www.epa.gov/npdes/pubs/sso_fact_s heet_model_permit_cond.pdf >, which explains the ways NPDES permitting authorities should be improving implementation of NPDES permit requirements to address SSOs and sanitary sewer collection systems.

9-20 Chapter 9: Special ConditionsSeptember 2010 NPDES Permit Writers’ Manual

The draft fact sheet indicates that clarifications s hould 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 permitt ee is required to notify the NPDES authority of an overflow that could endanger h ealth 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 th e permittee becomes aware of the overflow. [See § 122.41(l)(6)].

 Written reports . Permits should clarify that the permi ttee 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. [S ee § 122.41(l)(6)(i).] In addition, permits should clarify that any overflow that is not immediatel y reported as indicated above, should be reported in the discharge monitoring report. [See § 122.41(l)(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 h ealth because of a likelihood of human exposure. Permits should clarify that the permittee is require d 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 byp ass 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 s hould be reported, the specific information that would be reported, a description of lines of communication, and the identities of responsible officials. [See § 122.41(l)(6)].

 Recordkeeping . Permits should clarify that the permi ttee is required to keep records of overflows. Clarified permit language for recordkeep ing should require the permittee to retain the reports submitted to the NPDES authority and othe r 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 § 122.41(j)].

 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 th e 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 Maintena nce (MOM) Progra ms Project Website

< www.epa.gov/region4/wate r/wpeb/momproject/ >. The CMOM program may use a process for selfassessment and information management techni ques for ongoing program improvement and may develop and implement emergency response pro cedures to overflows. In addition, the CMOM permit condition may specify appropriate documentation requirements, including the following:

− CMOM program summary. Permittees may be requi red 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.

Chapter 9: Special Conditions 9-21September 2010 NPDES Permit Writers’ Manual

9-22 Chapter 9: Special Conditions − Program audit report. Permittees may be require d 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 < www.epa.gov/npdes/sso/ssotoolbox > provides information on CMOM.

− System evaluation and capacity assurance plan. Capacity assurance refers to a process to identify, characterize and address hydraulic defici encies 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 faciliti es 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 di scharge 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 whic h 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 < www.epa.gov/npdes/sso > provide more information on SSOs.

1 U.S. Environmental Protection Agency. 1999. Toxicity Reduction Evaluation Guidance for Municipal Wastewater Treatment Plants . EPA/833B-99/002. U.S. Environmental Protection Agency, Office of Wastew ater Management, Washington, DC.

< www.epa.gov/npdes/pubs/tre.pdf >.

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 Regulato ry Enforcement, Washington, DC. < www.epa.gov/npdes/pubs/owmfinaltretie.pdf >.

3 U.S. Environmental Protection Agency. 1989. Generalized Methodology for Conductin g Industrial Toxicity Reduction Evaluations (TREs) . EPA-600/2-88-070. U.S. Environmen tal Protection Agency, Water Engi neering Research Laboratory, Cincinnati, OH. Publication available on NEPIS Website < www.epa.gov/nscep/ > as document 600288070.

4 U.S. Environmental Protection Agency. 1991. Methods for Aquatic Toxicity Identifi cation Evaluations: Phase I Toxicity Characterization Procedures. Second Edition . EPA-600/6-91-003. U.S. Environmental Pr otection Agency, Office of Research and Development, Washington, DC. < www.epa.gov/npdes/pubs/owm0330.pdf >.

5 U.S. Environmental Protection Agency. 1992. Toxicity Identification Evaluation: C haracterization of Chronically Toxic Effluents, Phase I . EPA-600/6-91-005F. U.S. Environmental Protection Ag ency, Environmental Research Laboratory, Duluth, MN. < www.epa.gov/npdes/pubs/owm0255.pdf >.

6 U.S. Environmental Protection Agency. 1993. Methods for Aquatic Toxicity Identifi cation 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. < www.epa.gov/npdes/pubs/owm0343.pdf >.

7 U.S. Environmental Protection Agency. 1993. Methods for Aquatic Toxicity Identifica tion 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. < www.epa.gov/npdes/pubs/owm0341.pdf >.

8 U.S. Environmental Protection Agency. 1995. Great Lakes 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, Wash ington, DC. Publication av ailable on NEPIS Website < www.epa.gov/nscep/ > as document 820B95005.

9 U.S. Environmental Protection Agency. 1993. Guidance Manual for Developing Best Management Practices. EPA 833-B-93- 004. U.S. Environmental Pr otection Agency, Office of Water, Washington, DC. < www.epa.gov/npdes/pubs/owm0274.pdf >

.

Endnotes for this chapter continued on the next page.September 2010 NPDES Permit Writers’ Manual

Chapter 9: Special Conditions 9-23 10 King, Ephraim S. 1992. Order Denying Modification Request With Respect to the Administrator’s 1990 Decision in Star-Kist Caribe, Inc. (NPDES Appeal No. 88-5). U.S. Environmental Protection Agency, Office of Water. Memorandum, May 27, 1992.

< www.epa.gov/npdes/pubs/owm0121.pdf >.

11 Hanlon, James. A. 2007. Compliance Schedules for Water Quality-Based Effluent Limitations in NPDES Permits. U.S. Environmental Protection Ag ency, Office of Wastewater Ma nagement. Memorandum, May 10, 2007.

< www.epa.gov/npdes/pubs/memo_com plianceschedules_may07.pdf >.

12 U.S. Environmental Protection Agency. 1999. Introduction to the National Pretreatment Program. EPA-833-B-98-002. U.S. Environmental Protection Ag ency, Office of Wastewater Management, Wash ington, D.C.

< www.epa.gov/npdes/pubs/final99.pdf >.

13 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.

< www.epa.gov/owm/mtb/biosolids/503pe/ >.

14 U.S. Environmental Protection Agency. 1995. A Guide to the Biosolids Risk Assessments for the EPA Part 503 Rule . EPA/832- B-93-005. U.S. Environmental Prot ection Agency, Office of Wastewat er Management, Washington, DC.

< www.epa.gov/owm/mtb/biosolids/503rule/ >.

15 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. < www.epa.gov/npdes/pubs/owm0237.pdf >.

16 U.S. Environmental Protection Agency. 1994. Land Application of Sewage Sludg e—A 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. < www.epa.gov/npdes/pubs/sludge.pdf >.

17 U.S. Environmental Protection Agency. 1994. Surface Disposal of Sewage Sludge—A 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 av ailable on NEPIS Website < www.epa.gov/nscep/ > as document 831B93002c.

18 U.S. Environmental Protection Agency. 1993. Preparing Sewage Sludge for Land Appl ication or Surface Disposal—A Guide for Preparers of Sewage Sludge on the M onitoring, Recordkeeping, and Reporting Require ments of the Federal Standards for the Use or Disposal of Sewage Sludge in 40 CFR Part 503 . EPA-831/B-93-002a. U.S. Environmen tal Protection Agency, Office of Water, Washington, DC. Publicati on available on NEPIS Website < www.epa.gov/nscep/ > as document 831B93002a.

19 U.S. Environmental Protection Agency. 1993. Domestic Septage Regulatory Guidance—A Guide to the EPA 503 Rule

. EPA-832/B-92-005. U.S. Environmen tal Protection Agency, Office of Water, Washington, DC.

< www.epa.gov/npdes/pubs/owm0026.pdf >.

20 U.S. Environmental Protec tion Agency. 1992, Rev. 2003. Control of Pathogens and Vect or Attraction in Sewage Sludge

. EPA-625/R-92-013. U.S. Environmental Pr otection Agency, Office of Research and Development, Washington, DC.

< www.epa.gov/nrmrl/pubs/625r92013/625R92013.pdf >.

21 U.S. Environmental Protection Agency. 1995. Combined Sewer Overflows–Guidance for Long-Term Control Plan

. EPA-832/B-95-002. U.S. Environmen tal Protection Agency, Office of Water, Washington, DC.

< www.epa.gov/npdes/pubs/owm0272.pdf >.

22 U.S. Environmental Protection Agency. 1995. Combined Sewer Overflows–Guidance for Nine Minimum Controls

. EPA-832/B-95-003. U.S. Environmen tal Protection Agency, Office of Water, Washington, DC.

< www.epa.gov/npdes/pubs/owm0030.pdf >.

23 U.S. Environmental Protection Agency. 1995. Combined Sewer Overflows–Guidance for Screening and Ranking . EPA-832/B95-004. U.S. Environmental Protection Agency, Offi ce of Wastewater Management, Washington, DC.

< www.epa.gov/npdes/cso >.

24 U.S. Environmental Protection Agency. 1995. Combined Sewer Overflows–Gui dance for Monitoring and Modeling . EPA832/B-99-002. U.S. Environmenta l Protection Agency, Office of Water, Washington, DC.

< www.epa.gov/npdes/pubs/sewer.pdf >.

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 Agen cy, Office of Water and Office of Wastewater Management, Washington DC. < www.epa.gov/npdes/pubs/csofc.pdf >.

26 U.S. Environmental Protection Agency. 1995. Combined Sewer Overflows–Guidance for Funding Options . EPA-832/B-95- 007. U.S. Environmental Pr otection Agency, Office of Water, Washington, DC. < www.epa.gov/npdes/pubs/owm0249.pdf >.

Endnotes for this chapter continued on the next page.September 2010 NPDES Permit Writers’ Manual

9-24 Chapter 9: Special Conditions 27 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. < www.epa.gov/npdes/cso >.

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. < www.epa.gov/npdes/pubs/w qs_guide_final.pdf >.

29 U.S. Environmental Protection Agency. 2004. Report to Congress on the Impacts and Control of CSOs and SSOs. EPA 833-R04-001. U.S. Environmental Protection Agen cy, Office of Water, Washington, DC. < www.epa.gov/npdes/csossoreport2004 >.September 2010 NPDES Permit Writers’ Manual

Chapter 10: Standard Conditions of NPDES Permits 10-1 

## CHAPTER 10. Standard Conditions of NPDES Permits

This chapter describes standard conditions, sometimes called boilerplate conditions, that must be incorporated in National Pollutant Discharge Elimin ation 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 limita tions, monitoring and reporting requirements, and special conditions because they delineate various legal, administrative, a nd procedural requirements of the permit. Standard conditions cover various topics, incl uding definitions, testing procedures, records retention, notification requirements, penalties for noncompliance, and othe r permittee responsibilities. The conditions provided in § 122.41 apply to all types and categories of NPDES permits and must be incl uded 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 add itional conditions, as applicable.
The use of standard conditions helps ensure uniform ity 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 standa rd 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 wr iters 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 in cludes the federal standard conditions.



## 10.1 Types of Standard Conditions
A brief summary of the § 122.41 standard conditions th at 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 Wa ter 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 rea pply 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 th at 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 viola tion 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.September 2010 NPDES Permit Writers’ Manual

The permittee must provide appropriate laborator y controls and quality assurance procedures. Operation of backup systems is required onl y 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 pe rmit modification, revocation or reissuance, termination, or a notification of planned chang es 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 wi th 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 measureme nts 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(l)(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 signifi cantly change sludge use or disposal practices.

 Anticipated Noncompliance § 122.41(l)(2): The permittee must give advance notice of any planned changes that could result in noncompliance.

 Permit Transfers § 122.41(l)(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(l)(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 pro cedures specified in the permit must also be reported. Calculations requiri ng averaging must use an arithmetic mean unless otherwise specified in the permit.

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 Compliance Schedules § 122.41(l)(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(l)(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 includi ng 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 Di rector 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(l)(7): The permittee must report all instances of noncompliance not reported under other specific reporting requi rements at the time monitoring reports are submitted.

 Other Information § 122.41(l)(8): If the permittee becomes aware that it failed to submit any relevant facts in its applicati on, 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 operatio n (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 fo r a bypass, unless the bypass was unavoidable to prevent loss of life, personal injury, or severe pr operty damage, there was no feasible alternative, and the proper notification was submitted.

 Upset § 122.41(n): An upset (i.e., an exceptional in cident 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 affirmativ e defense in actions brought against the permittee for noncompliance. An upset does not include nonc ompliance 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 h as 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 appli cable to various types of NPDES permits.

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10-4 Chapter 10: Standard Conditions of NPDES Permits 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)(1) 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 introduc tion 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-designated municipal separate storm sewer syst ems are in § 122.42(c). Those standard conditions require that the permittee submit an annual report ad dressing the status, and changes to, the stormwater management program, water quality data and other information sp ecified in §§ 122.42(c)(1)-(6).

Individual Stormwater Permits : Initial permits for discharges composed entirely of stormwater and permitted under § 122.26(e)(7) must require complian ce 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 include d in all permits for CAFOs.September 2010 NPDES Permit Writers’ Manual

Chapter 11: NPDES Permit Administration 11-1 

## 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 issuan ce 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 Appli cable 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 requi rements imposed under these statutes only apply to federal actions (i.e., U.S. Environmental Protection Ag ency [EPA] issuance of permits). Permits issued by states authorized to administer the NPDES program ar e not subject to the requirements of these statutes. However, many states may have enacted state legislati on 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 r esponsible 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.

Exhibit 11-1 Other federal laws applicable to NPDES permits

Federal law Year Federal agency Legislative citations Implementing regulations Endangered Species Act (ESA) 1973 FWS, NMFS 16 U.S.C. 1531 et seq. 50 CFR Part 402 National Environmental Policy Act (NEPA) 1969 CEQ 42 U.S.C. 4321 et seq. 40 CFR Part 6 National Historic Preservation Act (NHPA) 1992 ACHP 16 U.S.C. 470 et seq. 36 CFR Part 800 Coastal Zone Management Act (CZMA) 1972 NOAA 16 U.S.C. 1451 et seq. 15 CFR Part 930 Wild and Scenic Rivers Act 1968 Various 16 U.S.C. 1271 et seq. 36 CFR Part 297 Fish and Wildlife Coordination Act (FWCA) 1934 FWS 16 U.S.C. 661 et seq. -- Essential Fish Habitat Provisions (EFH) 1996 NOAA 16 U.S.C. 1855(b)(2) 50 CFR Part 600



### 11.1.1 Endangered Species Act This section discusses procedures intended to protect enda ngered species that apply only to permits issued by EPA. The 1973 Endangered Species Act (ESA) < www.fws.gov/endangered/esa- library/pdf/ESAall.pdf >, 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) < www.fws.gov/endangered/ > of the Department of the Interior and the National Marine Fisheries Service (NMFS) < www.nmfs.noaa.gov/pr/ > of the NationalSeptember 2010 NPDES Permit Writers’ Manual

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 jeopa rdize 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 < www.fws.gov/endangered/esa-lib rary/pdf/TOC-GLOS.PDF > to address the major consultation processes pursuant to ESA section 7.
Consultation may be either informal or formal. An in formal 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 likeli hood for adverse impacts and evaluates whether the proposed action is likely to jeopardize the continued ex istence of the species. It is EPA’s responsibility to ensure that consultation occurs; however, a nonfed eral 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 MOA )

< www.epa.gov/fedrgstr/EPA-SPECIES /2001/February/Day-22/e2170.pdf > 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 stateissued permits. EPA permit writers should review the ESA consultation regula tions and the ESA section 7 Consultation Handbook, and coor dinate with the Region’s ESA coor dinator (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 procedur es that apply only when EPA issues permits to new

sources (dischargers subject to New Source Performance Standards). The 1969 National Environmental Policy Act (NEPA) < www.epa.gov/compliance/basics/nepa.html >, 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) < www.whitehouse.gov/ceq/ > coordinates federal environmental efforts to comply with NEPA.

Within EPA, the Office of Federal Activities under th e Office of Enforcement and Compliance Assurance (OECA) is responsible for EPA’s implementation of NEPA < www.epa.gov/compliance/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 la w versions of NEPA. Fede ral permit writers should coordinate efforts with the Office of Federal Ac tivities 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) < www.achp.gov/nhpa.html >, 16 U.S.C. 470 et seq. , as amended, and implem enting regulations 36 CFR Part 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 mitig ate potential adverse effect s of the licensed activity and properties listed or eligib le for listing in the National Register of Historic Places.
The Act’s requirements are to be implemented in cooperation with State Historic Preservation Officers

< www.achp.gov/shpo.html >, and upon notice to, and when appr opriate, in consultation with the Advisory Council on Historic Preservation < www.achp.gov/ >, which provides national oversight for the NHPA. A decision by the D.C. Circuit in 2003 concluded that NHPA consultation is not required for state-issued permits ( National Mining Ass’n v. Fowler , 324 F.3d 752 (D.C. Cir. 200 3) < caselaw.findlaw.com/us-dccircuit/1169695.html >).
Federal permit writers should ev aluate 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) < www.coastalmanagement.no aa.gov/czm/czm _act.html >, 16 U.S.C. 1451 et seq. , was enacted to manage the nation’s coast al 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 th e 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 territo ries 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 require d, as a condition of receipt of federal grant money under the CZMA, to adopt coastal management pl ans, 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 < www.coastalmanagement.noaa.gov/ >, 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 pe rmit 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) < www.rivers.gov/public ations/wsr-act.pdf >, 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. Ri vers 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 assis ting, 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 WS RA regulations are codified at 36 CFR Part 297.
Federal permit writers should verify whether the recei ving water is part of the System and document all activities related to the Act in the permit file and f act sheet. For detailed explanation of WSRA section 7, refer to Wild and Scenic Rivers Act: Section 7 < www.rivers.gov/publications/section-7.pdf >, a technical report of the Interagency Wild and Scenic Rivers Coordi nating Council. Permit writers may also refer to Water Quantity and Quality as Related to the Management of Wild and Scenic Rivers

< www.rivers.gov/publications/water.pdf >, 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) < www.fws.gov/ha bitatconservation/fwca.html >, 16 U.S.C. 661 et seq. , requires mitigation for the loss of wildlife habitat due to the c onstruction 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 cons ult 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 Interi or 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 NPD ES 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 < www.fws.gov/habitatconservation/fwca.pdf > provides the FWS guidance on implementing the FWCA. Federal pe rmit 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) prom ote 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 co nsultation 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

< www.habitat.noaa.gov/prote ction/efh/index.html >. 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 pe rmit 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 docu mentation (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 thr oughout 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 documenta tion 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 (i f appropriate), and responding to public
comments.

 Defending the permit and modifying it (if necessary) after issuance.
Note that Exhibit 11-3 provides the general framewo rk 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 require ments 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 procedur es 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

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Exhibit 11-4 Typical administrative pro cess for state-issued NPDES permits*

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### 11.2.1 Administrative Record 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 whet her 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 justifi cation 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 th e permit issuing office or published material that is generally available do not need to be physically incl uded with the record as long as they are specifically referred to in the fact sheet or statement of basi s. 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 administ rative records for a draft permit

 Permit application and supporting data

 Draft permit

 Statement of basis or fact sheet

 All items cited in the statement of basis or fa ct sheet, including calculations used to derive the permit limitations

 Meeting reports

 Correspondence with the applicant and regulatory personnel

 All other items in the supporting file

 For new sources, any EA, dra ft/final EIS, or other such backg round information, such as a Finding of No Significant Impact (only applies if EPA issues the permit)

The administrative record should include all meeti ng 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 avoide d. Finally, the presentation of calculations and documentation of decisions should be organized in su ch a way that they can be reconstructed and the logic supporting the calculation or decisions can easily be found.



### 11.2.2 Fact Sheets and Statements of Basis 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 documenta tion 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 th at 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 fo r 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 m odification 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 descrip tion 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 requirem ents 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 § 124.56

 Reasons why any requested variances do not appear justified, if applicable § 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 perso n 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 re lated 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 B est 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 wastel oad 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 we re not included in the draft permit as it is to keep a record of included items. Such r ecords 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 th at water quality standards would be attained)?

 Why was biomonitoring not included?

 Why were pollutants that were reported as presen t 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, pro cedures for requesting a hearing, and other means of public involvement in the final decision.

A statement of basis, as described in § 124.7, is re quired 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 activiti es 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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### 11.3.1 Public Notice The public notice is the vehicle for informing all inte rested parties and members of the general public of the contents of a draft NPDES permit or other signifi cant 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 no tice 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 (n ot 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 w ith 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 interest ed 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 re quired to issue a Resource Conservation and Recovery Act (RCRA), Underground Injection Control (UIC), Prevention of Significant Deterioration (PSD) (or other permit under th e 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 A dvisory Council on Historic Preservation, State Historic Preservation Officers, including any affected states and tribes.

− State agencies conducting area-wide and continui ng 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 incl uding 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 contac t from whom interested persons can obtain additional information

 A brief description of the comment procedures requ ired, the time and place of any hearing to be held including procedures to request a hearing

 For EPA-issued permits, the locati on and availability of the administrative reco rd and the times at which the record will be open for public inspection and a statement that a ll 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 prac tice(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 in take 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 noti ce 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.



### 11.3.2 Public Comments 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 th e draft permit or indicate that the draft permit is inappropriate for various reasons. In such cases, co mmenters must submit all reasonable arguments and factual material in support of their positions and co mments by the close of the public comment period, and the permitting authority must consider those co mments in making final decisions. If the approach is technically correct and clearly stated in the fact sh eet, 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 prov iding further explanation of permit terms and conditions. Add itionally, 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 dr aft 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 durin g 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 th e response to comments must be included in the administrative record. If new points are raised or ne w 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.



### 11.3.3 Public Hearings 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 th e 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 hearin g 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 l east 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 th e 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 ex tended by request during the hearing. Anyone may submit written or oral comments concerning th e draft permit at the hearing. A presiding officer is responsible for scheduling the hearing and maintaini ng orderly conduct, includ ing setting reasonable time

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limitations for oral statements. Note that a transcrip t or recording of the hearing must be available to interested persons.



### 11.3.4 Environmental Justice Considerations Environmental justice (EJ) is the fair treatment a nd 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 M OA 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 pe rmit. 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 othe r 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 w ith 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 aver age 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 recomme ndations 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 th at 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 ob jection 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 w ithdraw 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 da ys 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 di scharge 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 prom oting consistency between state-issued and EPA-issued permits where not all permits within the stat e 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)(1), 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 r easonable 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 dr aft 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 pro cess 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 th e 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 administ rative records for a final permit

 All elements for the draft permit admin istrative 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 (ICISNPDES) (for more on ICIS-NPDES, see the introducti on to this manual and section 11.5.1.1 below). Entering permit information into ICIS-NPDES will ensu re 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 ha ve opportunities to change the permit through permit appeals, major/minor permit modifications, terminati on and revocation, or transfer. Those administrative procedures are described below.



### 11.4.1 Permit Appeals Throughout the process of developing a permit and during the public notice period, the permit writer should carefully consider all legitimate concerns of th e applicant/permittee and any other interested party. Nevertheless, there will inevitably be situations in wh ich a permit is issued in spite of the objections of the permittee or a third party. In such instances, th e 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 ma y contest the final limitations and conditions in a permit.
Appeals of EPA-issued permits consist of petitioni ng the Environmental Appeals Board (EAB) for review. Such review must be requested within 30 da ys 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 re view 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 fili ng 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 a nd will need to address the types of issues discussed below.
Aside from preparing the administrative record and noti ces, the permit writer might not be involved in the procedural matters relating to permit appeals. All re quests for permit appeals are coordinated through the office of the EPA Regional Counsel or the appropria te 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 woul d otherwise occur in the hearing. The deposition is transcribed and presented as evidence. The appellant atto rney 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, an d policies that could affect the permit. The permit writer should also be thoroughly familiar with the t echnical 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 m odels, 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 th e effluent limitations and should be sure that the information on which case-by-case limitations are base d 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 info rmation 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 writ er’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 pro cess could include developing questions for crossexamination of opposing witnesses in a state permit a ppeal that involves a hearing. Questions should be restricted to the subject material covered by the witn ess’ 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 wh en 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 witn ess, 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 appeal s in the initial stage of granting review. If that is not possible, the EAB conducts formal review of th e 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 circ umstances, 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 cond itions 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 perm it 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 representa tive 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 th e need for a change. Of course, any interested person may make a request for a permit modification.

Modifications differ from revocations and reissuan ce. 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 su mmarized 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 th ose specific conditions being modified are open to review and comment. The permitting aut hority 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 cond itions 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 efflue nt limitations on a net bas is 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 comp liance 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 anot her 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 treat ment requirements appropriate to the permit.

 Notification levels : To establish notification levels for to xic 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 requ ired 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 impl ementation and the other en tity fails to fulfill its responsibility to implement such measure(s).

 Technical mistakes : To correct technical mistakes or mistaken in terpretations of law ma de 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 limitat ions, 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 Dir ector 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 c onsent of the permittee, may be processed by the permitting authority without following the procedures fo r public notice in Part 124. Minor modifications are generally non-substantive changes (e.g., typographi cal 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 schedul e 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 Permit Termination Situations could arise during the life of the permit th at are causes for termination of the permit. Such circumstances, described in § 122.64(a), include the following:

 Noncompliance by the permittee w ith any condition of the permit.

 Misrepresentation or omission of relevant facts by the permittee.

 Determination that the permitted ac tivity 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 priv ileges to discharge during the permit term. A notice of intent to terminate a permit is a type of draft pe rmit 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 terminat ed 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 excep tion to the more formal permit termination process described above. Where the entire discharge is permanen tly 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 administrativ e 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 pe rmit 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 al so be addressed by revoking and subsequently reissuing the permit.

 Automatic transfer : A permit may automatically be tran sferred 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 respons ibility, 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 a nd 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 wr itten 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 depe nd on the organizational structure of the regulatory agency. Larger, centrally organized agencies typically have separat e 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 disch arge monitoring report (DMR) tracking, facility inspections, and enforcement recommendations. If a civil judicial enfo rcement 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 ICISNPDES (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 < www.epa.gov/compliance/ civil/cwa/index.html >.

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### 11.5.1 Compliance Monitoring Compliance monitoring is a broad term that includes a ll activities that federal or state regulatory agencies take to ascertain a permittee’s compliance with the c onditions 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, re viewing, and entering data into the ICIS-NPDES database, conducting on-site inspections, identifying vi olators, 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 sche dules. Compliance verification is achieved through

 Compliance review : A review of all written reports and othe r 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 primar y sources of information to carry out compliance reviews:

 Permit/compliance files.

 The ICIS-NPDES database.
Permit/compliance files include the permit, appli cation, fact sheet, compliance schedule reports, compliance inspection reports, DMRs, enforcement actions, and correspondence (e.g., summaries of telephone calls, copies of warning le tters). Compliance personnel periodical ly 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 < https://icis.epa.gov/icis > 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, sel f-monitoring data, compliance schedules, permit conditions, inspections, and enforc ement 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 IC IS-NPDES and evaluate permittees on compliance with NPDES permit requirements. Inspecti on 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 followi ng 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 fo llow the compliance inspection procedures discussed in the next section.



### 11.5.1.2 Compliance Inspections Compliance inspections refer to all field-relate d regulatory activities conducted to determine permit compliance. Such field activities can include complia nce evaluation inspections (non-sampling), sampling inspections, other specialized inspections, and remo te sensing. Certain inspections, such as diagnostic inspections and performance audit inspections, aid th e regulatory agency in evaluating the facility’s problems in addition to providing information to su pport enforcement action. Biomonitoring inspections are specifically targeted at facilities with effluent susp ected or identified as causing toxicity problems that threaten the ecological balance of the receiving waters.
Compliance inspections are undertaken to fulf ill 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 pe rmittee’s performance and compliance records.

 Assess the adequacy of the permittee’s self-mon itoring 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 comp liance with the terms and conditions of their permit or enforcement order (i.e., that meet the criteria for reportable noncompliance [RNC] for effluent limitation, schedules, and reporting violations).
The regulations in § 123.45 establish requirements fo r 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. Th e 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 s hould be evaluated for magnitude by comparing the measured amount in the DMR to the product of th e monthly average limitation times the Technical Review Criteria (TRC) for that pollutant or para meter. 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 ma nagement 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 perm it limitations by major facilities. Many permits for NPDES major facilities lacked required monthly averag e limitations and, thus, were not evaluated for SNC violations and follow-up formal enforcement ac tion. 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 Vi olations of Non-Monthly Average Limits 1

< www.epa.gov/compliance/resources/polic ies/civil/cwa/revisedsncmemo.pdf >.
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 pa rameter, 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

11-24 Chapter 11: NPDES Permit AdministrationSeptember 2010 NPDES Permit Writers’ Manual

action has been taken, the facility is placed on the Wa tch 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 Enforcement EPA’s NPDES compliance and enforcement princi ples and recommendations are described in the NPDES Enforcement Management System (EMS) 2 < www.epa.gov/compliance/resources/policies/civil/cwa/emscwa-jensenrpt.pdf >. By choosing an appropriate enforcement res ponse 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 incl udes an assessment of the magnitude, frequency, and duration of violations. The permitting authority identifies significant violations and makes a determination of the appropriate enforcement respon se. 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 conditio ns and judicial penalties up to $32,500 per day per violation.

EPA Regions and authorized states have specific pro cedures 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 ad ministrative 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 th e 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 enforcem ent 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 consis tency, and the integrity of the NPDES program.

Chapter 11: NPDES Permit Administration 11-25September 2010 NPDES Permit Writers’ Manual

11-26 Chapter 11: NPDES Permit Administration Citizens can participate in the enforcement pro cess in a number of ways. Under the Freedom of Information Act, citizens have the right to request certain facility- s pecific 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 threat ened 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 reso lve a state or federal civil judicial enforcement action.
CWA section 505 allows any citizen to begin a civil j udicial 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 acti on 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 Nonc ompliance (SNC) Criteria to Addr ess Violations of Non-Monthly Average Limits. U.S. Environmental Protection Ag ency, Office of Enforcement and Compliance Assurance. Memorandum, September 21, 1995. < www.epa.gov/compliance/resources/policies/civil/cw a/revisedsncmemo.pdf >.

2 U.S. Environmental Protection Agency. 1989. The Enforcement Management System: National Pollutant Discharge Elimination System (Clean Water Act) . EC-G-1998-11b. U.S. Environm ental Protection Agency, Offi ce of Water, Washington, DC. < www.epa.gov/compliance/resources/policie s/civil/cwa/emscwa -jensen-rpt.pd f >.September 2010 NPDES Permit Writers’ Manual

Appendix A. Acronyms, Abbreviations and Glossary A-1 Appendix A. 

## Appendix A. Acronyms, Abbreviations and Glossary

This appendix contains two tables fo r 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 abbreviatio ns 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-1 presents the abbreviations used in the NPDES Permit Writers’ Manual

.

Exhibit A-1 Acronyms and abbreviations Acronym or abbreviation Full phrase Glossary 1Q10 1-day, 10-year Low Flow 7Q10 7-day, 10-year Low Flow 4AAP 4-Aminoantipyrine (used for detecting phenolic compounds colorimetrically) ACHP Advisory Council on Historic Preservation ACR Acute-to-Chronic Ratio AFO Animal Feeding Operation x AML Average Monthly Limitation x ASR Alternative State Requirement AWL Average Weekly Limitation x BA Biological Assessment BAT Best Available Technology Economically Achievable x BCT Best Conventional Pollutant Control Technology x BE Biological Evaluation BMP Best Management Practice x BOD Biochemical Oxygen Demand x BOD 5 5-day Biochemical Oxygen Demand BPJ Best Professional Judgment x BPT Best Practicable Control Te chnology Currently Available x CAAP Concentrated Aquatic Animal Production CAFO Concentrated Animal Feeding Operation x CBOD Carbonaceous Biochemical Oxygen Demand x CBOD 5 5-day Carbonaceous Biochemical Oxygen Demand CEQ Council on Environmental Quality CERCLA Comprehensive Environmental Response, Compensation and Liabilities Act CFR Code of Federal Regulations x cfs Cubic Feet per Second CGP Construction General Permit CMOM Capacity, Management, Operation and MaintenanceSeptember 2010 NPDES Permit Writers’ Manual

Exhibit A-1 Acronyms and abbreviations (continued) Acronym or abbreviation Full phrase Glossary COD Chemical Oxygen Demand x CSO Combined Sewer Overflow x CSS Combined Sewer System x CV Coefficient of Variation CWA Clean Water Act x CWIS Cooling Water Intake Structure CZMA Coastal Zone Management Act DMR Discharge Monitoring Report x DWO Dry Weather Overflow EA Environmental Assessment EAB Environmental Appeals Board EC Effect Concentration EFH Essential Fish Habitat EIS Environmental Impact Statement ELG Effluent Limitations Guidelines or Effluent Guidelines x EMS Enforcement Management System eNOI Electronic Notice of Intent EPA U.S. Environmental Protection Agency ESA Endangered Species Act FDF Fundamentally Different Factors x FR Federal Register FWCA Fish and Wildlife Coordination Act FWPCA Federal Water Pollution Control Act FWS U.S. Fish and Wildlife Service GC/MS Gas Chromatography /Mass Spectroscopy gpd Gallons per Day HEM Hexane Extractable Material IC Inhibition Concentration ICIS Integrated Compliance Information System I/I Infiltration/Inflow LA Load Allocation lbs/day Pounds per Day LC 50 Lethal Concentration to 50% of test organisms LOEC Lowest Observed Effect Concentration LTA Long-Term Average LTCP Long-Term Control Plan MDL Method Detection Limit x MDL Maximum Daily Effluent Limitation x MEP Maximum Extent Practicable μg/L Micrograms per Liter mg/L Milligrams per Liter mgd Million Gallons per Day x ML Minimum Level x

A-2 Appendix A. Acronyms, Abbreviations and GlossarySeptember 2010 NPDES Permit Writers’ Manual

Appendix A. Acronyms, Abbreviations and Glossary A-3 Exhibit A-1 Acronyms and abbreviations (continued) Acronym or abbreviation Full phrase Glossary MOA Memorandum of Agreement MS4 Municipal Separate Storm Sewer System x MSA Magnuson-Stevens Act MSGP Multi-Sector General Permit N/A Not Applicable NAICS North American Industrial Classification System x NEMI National Environmental Methods Index NEPA National Environmental Policy Act NHPA National Historic Preservation Act NMC Nine Minimum CSO Controls NMFS National Marine Fisheries Service NMP Nutrient Management Plan NOAA National Oceanic and Atmospheric Administration NOEC No Observable Effect Concentration NOI Notice of Intent NOV Notice of Violation NPDES National Pollutant Di scharge Elimination System x NRDC Natural Resources Defense Council NSCEP National Service Center for Environmental Publications NSPS New Source Performance Standards NTIS National Technica l Information Service O&G Oil and Grease OCPSF Organic Chemicals, Plastics, and Synt hetic Fibers Point Source Category OECA EPA Office of Enforcement and Compliance Assurance ONRW Outstanding National Resources Waters OTIS Online Tracking Information System OW Office of Water OWRC Office of Water Resource Center PCS Permit Compliance System POTW Publicly Owned Treatment Works x PSD Prevention of Signif icant Deterioration PSES Pretreatment Standards for Existing Sources PSNS Pretreatment Standards for New Sources QNCR Quarterly Noncompliance Report RAPP Refuse Act Permit Program RCRA Resource Conservation and Recovery Act RNC Reportable Noncompliance SIC Standard Industria l Classification x SIU Significant Industrial User x SNC Significant Noncompliance SOP Standard Operating Procedure SPCC Spill Prevention Control and Countermeasure x SS Suspended Solids xSeptember 2010 NPDES Permit Writers’ Manual

Exhibit A-1 Acronyms and abbreviations (continued) Acronym or abbreviation Full phrase Glossary SSO Sanitary Sewer Overflow x STORET EPA Storage and Retrieval Database x SWPPP Stormwater Pollution Prevention Plan TBEL Technology-Based Effluent Limit(s) x TCDF Tetrachlorodibenzofuran TEC Transportation Equipment Cleaning Point Source Category THC Total Hydrocarbons TIE Toxicity Identification Evaluation TMDL Total Maximum Daily Load x TOC Total Organic Carbon x TRC Technical Review Criteria TRE Toxicity Reduction Evaluation x TRI Toxic Release Inventory TSD Technical Support Document [for Water Quality-based Toxics Control] TSS Total Suspended Solids x TTO Total Toxic Organics TU Toxic Units TUa Toxic Units – Acute TUc Toxic Units – Chronic TWTDS Treatment Works Treating Domestic Sewage x UAA Use Attainability Analysis UIC Underground Injection Control U.S.C. United States Code WET Whole Effluent Toxicity x VGP Vessel General Permit WLA Waste Load Allocation x WPD EPA Water Permits Division WQA Water Quality Act of 1987 WQBEL Water Quality-Based Effluent Limit(s) x WQS Water Quality Standard(s) x WSRA Wild and Scenic Rivers Act



## A.2 Glossary

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 paraphr ased 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 docume nt should be construed to alter or supplant any

A-4 Appendix A. Acronyms, Abbreviations and GlossarySeptember 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.

Exhibit A-2 Glossary

Term 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 t hat the proposed permit will comply with state water quality standards and other state requirements. 1996 U.S. EPA NPDES Permit Writers’ Manual (1996 PWM)

< www.epa.gov/npdes/pubs/o wm0243.pdf >

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 hea lth, an acute effect is not always measured in terms of lethality. 1996 PWM

Animal Feeding Operation (AFO) Lot or facility (other than an aquatic animal production facility) where the following conditions are met:

 Animals (other than aquatic anim als) 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, pe rmit conditions, or standards that are less stringent than those established in the previous permit. For more information on anti-backsl iding, 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 pr otection 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 1996 PWM

Authorized Program or Authorized State A state, territorial, tribal, or in terstate NPDES program that has been approved or authorized by EPA under Part 123. 1996 PWM

Average Monthly Discharge Limitation The highest allowable average of daily discharges over a calendar month, calculated as t he sum of all daily discharges measured during that month divi ded 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 establish ed by the CWA as the most appropriate means available on a national basis for controlling the direct discharge of toxic a nd 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 1996 PWM

Appendix A. Acronyms, Abbreviations and Glossary A-5September 2010 NPDES Permit Writers’ Manual

Exhibit A-2 Glossary (continued)

Term Definition Citation

Best Conventional Pollutant Control Technology (BCT) 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 se cond test examines the costeffectiveness of additional industrial treatment beyond BPT. EPA must find limits which are reasonable under both tests before establishing them as BCT. 1996 PWM

Best Management Practice (BMP) Schedules of activities, prohibit ions 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. § 122.2

Best Practicable Control Technology Currently Available (BPT) The first level of technology standards established by the CWA to control pollutants discharged to waters of the U.S. BPT limitations in effluent guidelin es are generally based on the average of the best existing performance by plants within an industrial category or subcategory. Adapted from 1996 PWM

Best Professional Judgment (BPJ) 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. 1996 PWM

Bioassay A test used to evaluate the relati ve 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. 1996 PWM

Biochemical Oxygen Demand (BOD) 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 organi c content of a wastewater. 1996 PWM

Biosolids See Sewage Sludge

. --
Bypass The intentional diversion of wast e streams from any portion of a treatment facility. This definit ion applies to both direct and indirect discharges. § 122.41(m)(1)(i) and § 403.17

Carbonaceous Biochemical Oxygen Demand (CBOD) 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. --

Categorical Industrial User (CIU) An industrial user subject to national categorical pretreatment standards. 1996 PWM

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 subcategor ies established as separate regulations under the appropriate subpart of 40 CFR chapter I, subchapter N. Adapted from § 403.6

A-6 Appendix A. Acronyms, Abbreviations and GlossarySeptember 2010 NPDES Permit Writers’ Manual

Appendix A. Acronyms, Abbreviations and Glossary A-7 Exhibit A-2 Glossary (continued)
Term Definition Citation

Chemical Oxygen Demand (COD) A measure of the oxygen-consum ing 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 1996 PWM

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 ef fect can be reduced growth, reduced reproduction, and such, in addition to lethality. 1996 PWM

Clean Water Act (CWA) The Clean Water Act is a statute passed by the U.S. Congress to control water pollution. It wa s 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. 1996 PWM

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. 1996 PWM

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 or snowmelt). During periods of wet weather, these systems become overloaded, bypass treatment works, and discharge directly to receiving waters at designed overflow points. 1996 PWM

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. 1996 PWM

Compliance Schedule (or Schedule of Compliance) A schedule of remedial measures included in a permit, including an enforceable sequence of interi m 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. 1996 PWM

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 ex pressed in other units of measurement, the daily discharge is calculated as the average measurement of the pollutant over the day. § 122.2September 2010 NPDES Permit Writers’ Manual

A-8 Appendix A. Acronyms, Abbreviations and Glossary Exhibit A-2 Glossary (continued)
Term 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.

< www.epa.gov/OCEPAterms/ dterms.html >

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 1996 PWM

Director The Regional Administrator or t he State Director, as the context requires, or an authorized repres entative. 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. (F or example, when EPA has issued an NPDES permit before the approval of a state program, EPA may retain jurisdic tion 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 subsequentadditions, revisions, or modifications for the reporting of selfmonitoring 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. § 131.3September 2010 NPDES Permit Writers’ Manual

Appendix A. Acronyms, Abbreviations and Glossary A-9 Exhibit A-2 Glossary (continued)
Term Definition Citation

Fact Sheet 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, lega l, 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). 1996 PWM

Fundamentally Different Factors (FDF) Those components of a petitioner’s facility that are determined to be so unlike those components considered by EPA during the effluent guidelines and pretreatm ent standards rulemaking that the facility is worthy of a variance from the effluent guidelines or categorical pretreatment standar ds that would otherwise apply. Adapted from 1996 PWM

General Permit 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. 1996 PWM

Grab Sample A sample taken from a wastestr eam on a one-time basis without consideration of the flow rate of the wastestream and without consideration of time. Adapted from 1996 PWM

Hazardous Substance Any substance—as designated under Part 116 pursuant to CWA section 311—that presents an imminent and substantial danger to the public health or welf are, including fish, shellfish, wildlife, shorelines, and beaches, upon discharge to navigable waters of the United States. Adapted from § 122.2 and CWA section 311(b)(2)(A)

Indirect Discharger A nondomestic discharger introducing pollutants to a publicly owned treatment works. 40 CFR 122.2

Instantaneous Maximum Limit The maximum allowable concentration or other measure of a pollutant determined from t he analysis of any discrete or composite sample collected, independent of the flow rate and the duration of the sampling event. 1996 PWM

Instantaneous Minimum Limit The minimum allowable concentration or other measure of a pollutant determined from t he analysis of any discrete or composite sample collected, independent of the flow rate and the duration of the sampling event. --

Load Allocation The portion of a receiving water's loading capacity that is attributed either to one of its ex isting 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. § 130.2

Local Limits 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). Adapted from § 403.4(d)September 2010 NPDES Permit Writers’ Manual

A-10 Appendix A. Acronyms, Abbreviations and Glossary Exhibit A-2 Glossary (continued)
Term Definition Citation

Major Facility 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 appr oved 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. 1996 PWM

Method Detection Limit (MDL) 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. § 136 - Appendix B

Maximum Daily Effluent Limitation (MDL) The highest allowable daily discharge of a pollutant. (Chapter 6) --

Million Gallons per Day (or mgd) A unit of flow commonly used for wastewater discharges. One million gallon per day is equivalent to 1.547 cubic feet per second. 1996 PWM

Minimum Level (ML) The level at which the entire a nalytical system must give a recognizable signal and acceptable calibration point. It is equivalent to the concentratio n of the lowest calibration standard, assuming that all met hod-specified sample weights, volumes, and cleanup procedures have been employed. § 136 - Appendix A

Mixing Zone 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. Technical Support Document for Water Quality-based Toxics Control

< www.epa.gov/npdes/pubs/o wm0264.pdf >

Municipal Separate Storm Sewer System (MS4) A conveyance or system of conveyances (including roads with drainage systems, municipal st reets, 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 P ublicly Owned Treatment Works (POTW) as defined at § 122.2. § 122.26(b)(8)

Municipal Sludge See Sewage Sludge

. --September 2010 NPDES Permit Writers’ Manual

Appendix A. Acronyms, Abbreviations and Glossary A-11 Exhibit A-2 Glossary (continued)
Term 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 pretreat ment 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 appl ies 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(l)

New Discharger Any building, structure, fa cility, or installation:
a. From which there is or may be a discharge of pollutants. b. That did not begin the di scharge 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, seaf ood 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 specif ied in §§ 125.122(a)(1) - 125.122(a)(10).

An offshore or coastal mobile ex ploratory 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 § 122.2September 2010 NPDES Permit Writers’ Manual

A-12 Appendix A. Acronyms, Abbreviations and Glossary Exhibit A-2 Glossary (continued)
Term Definition Citation

New Source Any building, structure, facility, or installation from which there is or could be a discharge of pollut ants, the construction of which commenced:
a. After promulgation of st andards 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 t he discharge of pollutants at an existing source; or iii. Its processes are substantially independent of an existing source at the same site. In determining whether these processe s 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. Standar ds consider that the new source facility has an opportunity to design operations to more effectively control pollutant discharges. 1996 PWM

Nonconventional Pollutants All pollutants that are not inclu ded 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. 1996 PWM

Nonpoint Source Diffuse pollution sources (i.e., without a single point of origin or not introduced into a receiving st ream from a specific outlet). The pollutants are generally carried off the land by stormwater. Atmospheric deposition and hydrom odification 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 statistica l data related to the U.S. business economy. Retrieved from

< www.census.gov/epcd/www/ naics.html >

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, terri torial, or tribal agency that has been authorized under CWA section 402(b) to administer the NPDES program within its jurisdiction. --September 2010 NPDES Permit Writers’ Manual

Appendix A. Acronyms, Abbreviations and Glossary A-13 Exhibit A-2 Glossary (continued)
Term 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. 1996 PWM

Point Source Any discernible, confined, and discrete conveyance, including any pipe, ditch, channel, tunnel, conduit, well, discrete fixture, container, rolling stock, concen trated animal f eeding 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, inciner ator residue, filter backwash, sewage, garbage, sewage sludge, munitions, chemical wastes, biological materials, radioactive materials (except those regulated under the Atomic Ener gy 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, to tal suspended solids). Adapted from 1996 PWM

Pollutant, NonConservative 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 1996 PWM

Pretreatment The reduction of the amount of pollutants, the elimination of pollutants, or the alteration of the nature of pollu tant 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.). 1996 PWM

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. 1996 PWMSeptember 2010 NPDES Permit Writers’ Manual

A-14 Appendix A. Acronyms, Abbreviations and Glossary Exhibit A-2 Glossary (continued)
Term Definition Citation

Process Wastewater Any water [that], during manufact uring or processing, comes into direct contact with, or resu lts from the production or use of any raw material, intermediate product, finished product, by-product, or waste product. § 122.2

Production-Based Standard A discharge standard expressed in terms of pollutant mass allowed per unit of product manufactured or some other measure of production. 1996 PWM

Proposed Permit 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

. § 122.2

Publicly Owned Treatment Works (POTW) 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, re cycling, 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. § 403.3(q)

Sanitary Sewer A pipe or conduit (sewer) intended to carry wastewater or waterborne wastes from homes, businesses, and industries to the POTW. 1996 PWM

Sanitary Sewer Overflows (SSO) Untreated or partially treated sewage overflows from a sanitary sewer collection system. 1996 PWM
Secondary Industry Category Any industry category, which is not a primary industry category

. § 122.2

Secondary Treatment 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 m unicipal sewage. Standards are expressed as a minimum level of effluent quality in terms of: BOD 5 , total suspended solids (TSS), and pH (except as provided by treatment equivalent to secondary treatment and other special considerations). Adapted from 1996 PWM

Section 304(a) Criteria Developed by EPA under authority of CWA section 304(a) based on the latest scientific info rmation 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. § 131.3(c)

Self-Monitoring Sampling and analyses performed by a facility to determine compliance with effluent limitations or other regulatory requirements. 1996 PWMSeptember 2010 NPDES Permit Writers’ Manual

Appendix A. Acronyms, Abbreviations and Glossary A-15 Exhibit A-2 Glossary (continued)
Term 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 wastew ater 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 t he focus of control efforts under the National Pretreatment Program.
SIUs 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 1996 PWM

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

< www.osha.gov/pls/imis/sic_manual.html > is available courtesy of the Occupational Safety & Health Administration (OSHA). Adapted from 1996 PWM

Statement of Basis A document prepared for every draft NPDES permit for which a fact sheet is not required. A stat ement of basis briefly describes how permit conditions were derived and the reasons the conditions are necessary for the permit. 1996 PWM

STORET EPA’s computerized STOrage and RETrieval water quality data base that includes physical, chemical, and biological data measured in waterbodies th roughout the United States. 1996 PWM

Storm Water (or Stormwater) Stormwater runoff, snow melt runoff, and surface runoff and drainage. § 122.26(b)(13)

Technology-Based Effluent Limitation (TBEL) An effluent limit for a pollutant t hat 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. TB ELs 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 1996 PWMSeptember 2010 NPDES Permit Writers’ Manual

A-16 Appendix A. Acronyms, Abbreviations and Glossary Exhibit A-2 Glossary (continued)
Term 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 1996 PWM

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, tri butaries, 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. 40 CFR § 130.2(i)

Total Suspended Solids (TSS) A measure of the filterable solids present in a sample, as determined by the method sp ecified in Part 136. 1996 PWM

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 e ffectiveness of toxicity control options, and then confirm the reduction in effluent toxicity. 1996 PWM

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. 1996 PWM

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:

< www.epa.gov/owow/watersh ed/trading/handbook/factsheet. html >

Treatability Manual Five-set library of EPA guidance manuals that contain information related to the treat ability 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. III – Technologies (EPA-600/8-80- 042c); Vol. IV – Cost Estimating (EPA-600/8-80-042d); and Vol. V – Summary (EPA-600/8-80-042e). 1996 PWM

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 storag e, 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 § 122.2September 2010 NPDES Permit Writers’ Manual

Appendix A. Acronyms, Abbreviations and Glossary A-17 Exhibit A-2 Glossary (continued)
Term Definition Citation

Upset An exceptional incident in wh ich there is unintentional and temporary noncompliance with technology-based permit effluent limitations because of factors be yond 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), 301(i), or 316(a). § 122.2

Wasteload 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 qual ity standards, expressed as constituent concentrati ons, levels, or narrative statements, representing a quality of water t hat 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 pub lic health or welfare, enhance the quality of water, and serv e the purposes of the CWA. Adapted from §131.3

Water QualityBased 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 1996 PWMSeptember 2010 NPDES Permit Writers’ Manual

A-18 Appendix A. Acronyms, Abbreviations and Glossary Exhibit A-2 Glossary (continued)
Term 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 la kes, 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 shel lfish 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. § 122.2September 2010 NPDES Permit Writers’ Manual

Appendix B. Index to the CWA and NPDES Regulations B-1 Appendix B. 

## Appendix B. Index to the CWA and NPDES Regulations

This appendix provides two tables to help permit wr iters 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 pr ovides 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-1 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 Engl and 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 1251 Congressional declaration of goals and policy 101 1252 Comprehensive programs for water pollution control 102 1253 Interstate cooperation and uniform laws 103 1254 Research, investigations, training and information 104 1255 Grants for research and development 105 1256 Grants for pollution control programs 106 1257 Mine water pollution demonstrations 107 1258 Pollution control in the Great Lakes 108 1259 Training grants and contracts 109 1260 Applications for training grants and contracts; allocations 110 1261 Scholarships 111 1262 Definitions and authorization 112 1263 Alaska village demonstration project 113 1265 In-place toxic pollutants 115 1266 Hudson River reclamation demonstration project 116 1267 Chesapeake Bay 117 1268 Great Lakes 118 1269 Long Island Sound 119 1270 Lake Champlain management conference 120 1273 Lake Pontchartrain Basin 121 1274 Wet weather watershed pilot projects 121 Subchapter II Grants for Cons truction of Treatment Works 1281 Congressional declaration of purpose 201 1282 Federal share 202 1283 Plans, specifications, estimates, and payments 203 1284 Limitations and conditions 204 1285 Allotment of grant funds 205 1286 Reimbursement and advanced construction 206 1287 Authorization of appropriations 207 1288 Area wide waste treatment management 208 1289 Basin planning 209September 2010 NPDES Permit Writers’ Manual

Exhibit B-1 Index to sections of the CWA (continued)
33 U.S.C. section Section title CWA section 1290 Annual survey 210 1291 Sewage collection system 211 1292 Definitions 212 1293 Loan guarantees 213 1294 Wastewater recycling and reuse information and education 214 1295 Requirements for American materials 215 1296 Determination of priority 216 1297 Guidelines for cost-effective analysis 217 1298 Cost effectiveness 218 1299 State certificati on of projects 219 1300 Pilot program for alternative water source projects 220 1301 Sewer overflow control grants 221 Subchapter III Standards and Enforcement 1311 Effluent Limitations 301 1312 Water quality-related effluent limitations 302 1313 Water quality standards and implementation plans 303 1314 Information and guidelines 304 1315 Water quality inventory 305 1316 National standards of performance 306 1317 Toxic and pretreatment effluent standards 307 1318 Records and reports, inspections 308 1319 Enforcement 309 1320 International pollution abatement 310 1321 Oil and hazardous substance liability 311 1322 Marine sanitation devices 312 1323 Federal facility pollution control 313 1324 Clean lakes 314 1325 National study commission 315 1326 Thermal discharges 316 1328 Aquaculture 318 1329 Nonpoint source management program 319 1330 National estuary study 320 Subchapter IV Permits and Licenses 1341 Certification 401 1342 National pollutant discharge elimination system 402 1343 Ocean discharge criteria 403 1344 Permits for dredge and fill materials 404 1345 Disposal or use of sewage sludge 405 1346 Coastal recreation water quality monitoring and notification 406 Subchapter V General Provisions 1361 Administration 501 1362 Definitions 502 1363 Water pollution control advisory board 503 1364 Emergency powers 504 1365 Citizen suits 505 1366 Appearance 506 1367 Employee protection 507 1368 Federal procurement 508 1369 Administrative procedure and judicial review 509 1370 State authority 510

B-2 Appendix B. Index to the CWA and NPDES RegulationsSeptember 2010 NPDES Permit Writers’ Manual

Appendix B. Index to the CWA and NPDES Regulations B-3 Exhibit B-1 Index to sections of the CWA (continued)
33 U.S.C. section Section title CWA section 1371 Authority under other laws and regulations 511 1251 Note Separability 512 1372 Labor standards 513 1373 Public health agency coordination 514 1374 Effluent standards and water quality information advisory committee 515 1375 Reports to Congress 516 1376 Authorization of appropriations 517 1377 Indian tribes 518 1251 Note Short Title 519 Subchapter VI State Water Pollution Control Revolving Funds 1381 Grants to States for estab lishment of revolving funds 601 1382 Capitalization grant agreements 602 1383 Water pollution control revolving loan funds 603 1384 Allotment of funds 604 1385 Corrective actions 605 1386 Audits, reports, fiscal controls, intended use plan 606 1387 Authorization of appropriations 607



## B.2 Index to NPDES Regulations
The index to NPDES regulations table presented in E xhibit B-2 was created by Sylvia Kawabata of EPA Region 10 on February 1, 1986, and is ma intained 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 § 122.21(m)(2) Part 125, Subpart E (reserved)

CWA section 301(g) – Modifications for Certain Nonconventional Pollutants § 122.21(m)(2) Part 125, Subpart F (reserved) Technical Guidance Manual for the Regulations Promulgated Pursuant to section 301(g) of the Clean Water Act of 1977 and 40 CFR Part 125 (Subpart F); August 22, 1984.
< www.epa.gov/npdes/pubs/owm0008.pdf > CWA section 301(h) – Secondary Treatment Waiver § 122.21(n)(1) Part 125, Subpart G CWA section 301(n) – Timetable fo r Achievement of Objectives See Fundamentally Different Factors

CWA section 316(a) – Thermal Discharges § 122.21(m)(6) Part 125, Subpart H § 124.57 § 124.62(a)(2) § 124.66 NPDES permit subjects Administrative Procedures Act Permit Continuance § 122.6

Administrative Record § 124.9 § 124.18September 2010 NPDES Permit Writers’ Manual

Exhibit B-2 Index to NPDES regulations (continued) Subject 40 CFR section number Alternate Test Procedures

 Application  § 136.4

 Approval  § 136.5 Ambient Monitoring (for Indicator Parameters) § 122.44(d)(1)(vi)(C)(3) Anti-backsliding See Backsliding Antidegradation Policy § 131.12 Applicability to State NPDES Programs See General Conditions for All Permits (State Programs) Application § 122.21

 Submittal Deadline (Time to Apply)  § 122.21(c)

 Permit May Not Be Issued Without Complete Application  § 122.21(e)

 Completeness  §§ 124.3(c) – 124.3(g) Aquaculture § 122.25 Part 125, Subpart B Aquatic Animal Production Facilities § 122.24

 Application  § 122.21(i)(2)

 Definition  § 122.24 Criteria for Determination Part 122, Appendix C

 General Permit  § 122.28 Average Monthly (D efinition) § 122.2

 Requirements for use in Non-POTWs  § 122.45(d)(1)

 Requirements for use in POTWs  § 122.45(d)(2) Average Weekly (Definition) § 122.2

 Requirements for use in POTWs  § 122.45(d)(2) Biochemical Oxygen Demand (BOD 5 ) § 133.101(d)

Backsliding § 122.44(l) § 122.62(a)(15) § 122.62(a)(17)

 From Water Quality and Technology Based Limits  CWA section 402(o)

 From Water Quality  CWA section 303(d)(4) Best Management Practices

 Definition  § 122.2 § 122.44(k) § 130.2(m)

 In Effluent Limitation Guidelines  CWA section 304(e)

 Case-by-Case Authority  CWA section 402(a)(1) Best Professional Judgment (BPJ)

 Case-by-Case Authority  §125.3(a)(1)

 Appropriate Factors  §§125.3(c) and 125.3(d) BMP See Best Management Practices Boilerplate Permit Cond itions §§ 122.41 - 122.42 BPJ See Best Professional Judgment Bypasses § 122.41(m) CAFO See Concentrated Animal Feeding Operations Calculating NPDES Permit Conditions § 122.45 Carbonaceous Biochemical Oxygen Demand (CBOD 5 ) § 133.101(e)

Case-by-Case Limitations See also BPJ § 122.44(a) § 125.3 Case-by-Case Permits See also BPJ § 124.52

B-4 Appendix B. Index to the CWA and NPDES RegulationsSeptember 2010 NPDES Permit Writers’ Manual

Appendix B. Index to the CWA and NPDES Regulations B-5 Exhibit B-2 Index to NPDES regulations (continued) Subject 40 CFR section number

Clean Water Act (CWA) (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 Coast Guard (Discharges from Transportation Over Water) § 122.44(p) Coastal Zone Management Act § 122.49(d) Combined Sewer Overflow Policy 59 FR 18688, April 19, 1994
< www.epa.gov/npdes/pubs/owm0111.pdf > Comments Received During Public Notice Period § 124.13

Compliance Schedules (in permits) § 122.41(l)(5) § 122.47 §§ 122.62(a)(4), (a)(9), (a)(13)

 Allowance by State Water Quality Standards  Star-kist Caribe, Inc., NPDES Appeal No. 88-5
< www.epa.gov/npdes/pubs/owm0121.pdf > (EAB, May 25, 1992) Computation of Time § 124.20 Concentrated Animal Feeding Operations § 122.23 Concentrated Aquatic Animal Production See Aquatic Animal Production Conditions Applicable to Specified Categories § 122.42 Confidentiality of Information § 122.7 Part 2 Consolidation of Permit Processing § 124.4 Continuation of Expired Permits § 122.6 Continuous Discharge § 122.45(d) Conventional Pollutants § 401.16

Cooling Water Intake Structures [CWA section 316(b)] Part 125, Subparts I, J and N § 122.21(r) § 401.14 DMR See Discharge Monitoring Report Daily Average See Average Monthly Daily Maximum See Maximum Daily

Definitions § 122.2 § 124.2 § 401.11 Denial of Permit § 124.6(b)

 Public Notice of Denial  § 124.10(a)(1)(i) Design Flow (POTWs) § 122.45(b)(1)
Dilution, Not A Substitute For Treatment § 122.45(f)(1)(iii) § 125.3(f) Discharge Monitoring Report (DMR) § 122.41(l)(4) Discharge of a Pollutant (Definition) § 122.2 Disposal into Wells, into POTWs, or by Land Application § 122.50 § 122.45(i) Draft Permit § 124.6 Dredged Materials (Discharge to Waters of the United States) CWA section 404 Duration of Permits § 122.46

 Computation of time  § 124.20 Duty to Comply § 122.41(a) Duty to Mitigate § 122.41(d) Duty to Provide Information § 122.41(h) Duty to Reapply § 122.41(b) Effect of a Permit § 122.5September 2010 NPDES Permit Writers’ Manual

B-6 Appendix B. Index to the CWA and NPDES Regulations Exhibit B-2 Index to NPDES regulations (continued) Subject 40 CFR section number Effective Date § 124.15 Effluent Limitations Guidelines (Effluent Guidelines or ELG) Parts 405-471 Endangered Species Act § 122.49(c) Enforcement Authority § 123.27 Environmental Impact Statement (EIS)

 EIS Public Notice of a New Source  § 124.10(b)(1)

 Final EIS  § 124.61

 New Source  § 122.29(c)

 NEPA  Part 6 Equivalent To Secondary Treat ment (for POTWs) § 133.105 Establishing Limitations, Standards § 122.44 Establishing Permit Conditions § 122.43 Evidentiary Hearing Procedures (Eliminated) §§ 124.21 (b) - (c) Exclusions § 122.3 Existing Source (Definition) § 122.29(a)(3) Expiration Dates See Duration of Permits Extension of Public Notice Comment Period § 124.12(c) FDF See Fundamentally Different Factors

Fact Sheets § 124.8 § 124.56 Feedlots See Concentrated Animal Feeding Operations Filter Backwash § 125.3(g) Fish and Wildlife Coordination Act § 122.49(e) Fish Farms See Aquatic Animal Production Facilities Flow Augmentation § 125.3(f) Flow Limits (POTW - Design Flow) § 122.45(b) Flow Monitoring Requirement § 122.44(i)(1)(ii)

Fundamentally Different Factors (FDF) § 122.21(m)(1) § 122.44(d)(8) Part 125, Subpart D Frequency of Sampling (Not less than once per year) § 122.44(i)(2) General Conditions Applicable to All Permits § 122.41 General Conditions for All Permits (State Programs) § 123.25 General Permits § 122.28

 Public Notice  § 124.10(c)(2)(i)

 Individual Permit Required  § 122.28(b)(3) Great Lakes Water Quality Guidance Part 132 Indian Tribe (Definition) § 124.2 Innovative Technology See CWA section 301(k) – Innovative Technology Inspection and Entry § 122.41(i) Internal Waste Streams § 122.45(h) Interim Dates for Schedules of Compliance § 122.47(a)(3) Introduction of New Pollutants (POTW) § 122.42(b)
Issuance and Effective Date § 124.15 § 124.60

Mass Limitations § 122.45(f) § 122.44(i)(1)(i) Maximum Daily (Definition) § 122.2

 Requirements for Non-POTWs  § 122.45(d)(1) Metals (To Be Expressed as Total Recoverable) § 122.45(c)September 2010 NPDES Permit Writers’ Manual

Appendix B. Index to the CWA and NPDES Regulations B-7 Exhibit B-2 Index to NPDES regulations (continued) Subject 40 CFR section number Method Detection Limit Part 136, Appendix B Minor Modifications § 122.63 Mixing Zones § 131.13
Modifications § 122.62 § 124.5 Monitoring Results, Requirements for Recording and Reporting § 122.48 Monitoring and Records § 122.41(j)

 Monitoring Reports  § 122.41(l)(4)

 Requirements  § 122.44(h)

 Recordkeeping  § 122.21(p) Municipal Separate Storm Sewer Systems (MS4)

 When Permit Required  §§ 122.26(a)(3), (4), and (5)

 Definitions  § 122.26(b)

 Large and Medium MS4s Application Requirements  § 122.26(d)

 Small MS4 Requirements  §§ 122.30 and 122.32 - 122.37

 Tribes  § 122.31 NPDES (Definition) § 122.2 National Environmental Policy Act (NEPA) § 122.49(g) National Historic Preservation Act § 122.49(b) Navigable Waters (Definition) § 110.1 Navigation § 122.44(q) Need to Halt or Reduce Activity, Not a Defense § 122.41(c) Net/Gross - Intake Credits § 122.45(g) New Discharger (Definition) § 122.2 New Source

 Definition  § 122.2

 Application Requirements  § 122.21(k)

 Program Requirements  § 122.29

 Determination  § 122.29(b)

 Mitigation Measures  § 122.44(d)(9)

 Prohibited discharges  § 122.4(i)

 Public Notice  § 124.10(a)(1)(vi) Non-Attainment Waters § 130.10(d) Non-Continuous Discharges § 122.45(e) Noncompliance

 Anticipated  § 122.41(l)(2)

 Other  § 122.41(l)(7) Notification Levels

 General  § 122.62(a)(12)

 For Existing Manufacturing, Commercial, Mining, and Silvicultural Dischargers  § 122.42(a)

 § 122.44(f) Ocean Discharge Criteria Part 125, Subpart M 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)  Part 125, Subpart N

 General Permit Requirements & Application  § 122.28(c) Effluent Guidelines and Standards Part 435, Subpart A Stormwater Exemption § 122.26(a)(2) Oil Pollution Prevention Part 112September 2010 NPDES Permit Writers’ Manual

B-8 Appendix B. Index to the CWA and NPDES Regulations Exhibit B-2 Index to NPDES regulations (continued) Subject 40 CFR section number On-Site Construction (New Source) § 122.29(b)(4) Operation and Maintenance § 122.41(e) pH Limits with Continuous Monitoring § 401.17 Planned Changes § 122.41(l)(1) Pollutant (Definition) § 122.2 POTWs, Applications for New and Existing § 122.21(j)

Pretreatment § 122.44(j) Part 403 Primary Industry Categories Part 122, Appendix A Prior Notice of Citizen Suits (Under CWA) Part 135 Priority Pollutants Part 423, Appendix A Privately Owned Treatment Works § 122.44(m) Production-based Limitations § 122.45(b) Prohibitions § 122.4 Proper Operation and Maintenance § 122.41(e) Property Rights § 122.41(g) Public Hearing § 124.12

 Public Notice for Public Hearings  § 124.10(b)(2) § 124.10(d)(2) Public Notice § 124.10

 Specific Procedures Applicable to NPDES Permits  § 124.57 Reapplication § 122.21(d)

Recordkeeping and Reporting § 122.21(p) § 122.41(j)(2) § 122.48 Reopener Clause

 Treatment Works Treating Domestic Sewage  § 122.44(c)

 Other  § 122.62(a)(7) Reopening of Public Comment Period § 124.14 Response to Comments § 124.17 Reasonable Potential (RP) - Need For A Limit § 122.44(d)(1)

 Chemical Specific  § 122.44(d)(1)(vi)

 Whole Effluent Toxicity (WET)  § 122.44(d)(1)(v) Retention of Records § 122.41(j)(2) Revocation and Reissuance § 122.62 Sample Type (Composite/Grab) § 122.21(g)(7)(i) Sample Holding Times, Containers, and Preservation § 136.3 Sample, Representative § 122.41(j) Schedule of Compliance (Definition) See also Compliance Schedule § 124.2 Secondary Treatment Regulation (POTW) Part 133

 Definitions  § 133.101

 Secondary Treatment  § 133.102

 Special Considerations  § 133.103

 Treatment Equivalent to Secondary Treatment  § 133.105 Signatory Requirements § 122.22 Silviculture § 122.27September 2010 NPDES Permit Writers’ Manual

Appendix B. Index to the CWA and NPDES Regulations B-9 Exhibit B-2 Index to NPDES regulations (continued) Subject 40 CFR section number Sludge (Definition) § 122.44(o)

 Sludge Standards  Part 503

 Land Application  Part 503, Subpart B

 Surface Disposal  Part 503, Subpart C

 Pathogens and Vector Attraction Reduction  Part 503, Subpart D

 Incineration  Part 503, Subpart E Sludge, Municipal Co-Disposal Landfills Part 258 Sludge-Only Facilities (Handlers) § 122.1(b)(3) Small Business Exemption § 122.21(g)(8) Solid Waste Facilities, Classification of Part 257 Spill Prevention, Control, and Countermeasures (SPCC) § 112.3 Standard Conditions §§ 122.41 and 122.42 State Certific ation § 124.53

 Applications for CWA section 301(h) Variances  § 124.54

 Effect of State Certification  § 124.55 State Program Requirements Part 123 Statutory Deadlines

 For POTWs  § 125.3(a)(1)

 For Non-POTWs  § 125.3(a)(2) Statutory Variances and Extensions § 125.3(b) Stays of Contested Permit Conditions § 124.16 Stormwater § 122.26

 Discharge Associated with Industrial Activity  § 122.26(b)(14) Test Methods, EPA Approved Part 136

Ten-Year Protection Period See also New Sources and Dischargers § 122.29 Termination of a Permit § 122.64 Thermal Discharge Variance See CWA section 316(a) – Thermal Discharges Total Maximum Daily Load (TMDL)

 Definition  § 130.2

 Which Waterbodies Need TMDLs  § 130.7

Toxics – Application and Testing § 122.21(g)(7) § 122.21(g)(9) § 122.21(g)(11) Toxic Pollutants (Definition) § 122.2

 Technology-based Controls  § 122.44(e) Toxic Pollutant List § 401.15 Toxicity Based Permit Limits § 125.3(c)(4) Transfer of Permit § 122.61 Treatment Works Treating Domestic Sewage Sludge (TWTDS) (Definition) § 122.2 Twenty-four Hour Reporting § 122.41(l)(6) Upset § 122.41(n) Variances for

 Non-POTWs  § 122.21(m)

 POTWs  § 122.21(n)

 Appeals of variances  § 124.64

 Decisions on variances  § 124.62

 Expedited variance procedures and time extensions  § 122.21(o)

 Procedures for variances when EPA is the permitting authority  § 124.63September 2010 NPDES Permit Writers’ Manual

B-10 Appendix B. Index to the CWA and NPDES Regulations Exhibit B-2 Index to NPDES regulations (continued) Subject 40 CFR section number Vessel (Definition) § 112.2 Waste Stabilization Ponds (POTW) § 133.103(c) Water Quality Report – CWA section 305(b) § 130.8 Water Quality Standards (WQS) Part 131

 Scope  § 131.1

 Purpose  § 131.2

 Definitions  § 131.3

 State Authority  § 131.4

 EPA Authority  § 131.5

 Submission, Minimum Requirements  § 131.6

 Dispute Resolution  § 131.7

 Establishment of Standards  § 131.10

 Criteria  § 131.11

 Antidegradation Policy  § 131.12

 General Policies on Establishing WQS  § 131.13

 State Review and Revision of WQS  § 131.20

 EPA Review and Approval of WQS  § 131.21

 EPA Promulgation of WQS  § 131.22

 Federally Promulgated Standards (State-By-State List)  Part 131, Subpart D Waters of the United St ates (Definition) § 122.2

Wetlands See Waters of the U.S. § 122.2 Whole Effluent Toxicity (WET) Limits § 122.44(d)(1)(iv) § 125.3(c)(4) WET Testing With Permit Application (POTWs) § 122.21(j) Wild and Scenic Rivers Act § 122.49(a) Withdrawal Of State Pr ogram §§ 123.63 - 123.64September 2010 NPDES Permit Writers’ Manual

Appendix C.

Appendix C. Priority Pollutants C-1 

## Appendix C. Priority Pollutants

Exhibit C-1 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

# Pollutant name # Pollutant name 001 Acenaphthene 067 Butyl benzyl phthalate 002 Acrolein 068 Di-N-Butyl Phthalate 003 Acrylonitrile 069 Di-n-octyl phthalate 004 Benzene 070 Diethyl Phthalate 005 Benzidine 071 Dimethyl phthalate 006 Carbon tetrachloride (tetrachloromethane) 072 1,2-benzanthracene (benzo(a) anthracene 007 Chlorobenzene 073 Benzo(a)pyrene (3,4-benzo-pyrene) 008 1,2,4-trichlorobenzene 074 3,4-Benzofluoranthene (benzo(b) fluoranthene) 009 Hexachlorobenzene 075 11,12-benzoflu oranthene (benzo(b) fluoranthene) 010 1,2-dichloroethane 076 Chrysene 011 1,1,1-trichloreot hane 077 Acenaphthylene 012 Hexachloroethane 078 Anthracene 013 1,1-dichloroethane 079 1,12-benz operylene (benzo(ghi) perylene) 014 1,1,2-trichlor oethane 080 Fluorene 015 1,1,2,2-tetrachloroet hane 081 Phenanthrene 016 Chloroethane 082 1,2,5,6-dibenzant hracene (dibenzo(,h) anthracene) 018 Bis(2-chloroethyl) ether 083 Indeno (,1,2,3-cd) pyrene (2,3-o-pheynylene pyrene) 019 2-chloroethyl vinyl ether (mixed) 084 Pyrene 020 2-chloronaphthalene 085 Tetrachloroethylene 021 2,4, 6-trichlorophenol 086 Toluene 022 Parachlorometa cresol 087 Trichloroethylene 023 Chloroform (trichloromethane) 088 Vinyl chloride (chloroethylene) 024 2-chlorophenol 089 Aldrin 025 1,2-dichlorobenzene 090 Dieldrin 026 1,3-dichlorobenzene 091 Chlordane (technical mixture and metabolites) 027 1,4-dichlorobenzene 092 4,4-DDT 028 3,3-dichlorobenzidine 093 4,4-DDE (p,p-DDX) 029 1,1-dichloroethylene 094 4,4-DDD (p,p-TDE) 030 1,2-trans-dichloroethylene 095 Alpha-endosulfan 031 2,4-dichlorophenol 096 Beta-endosulfan 032 1,2-dichloropropane 097 Endosulfan sulfate 033 1,2-dichloropropylene (1,3-dichloropropene) 098 Endrin 034 2,4-dimethylphenol 099 Endrin aldehyde 035 2,4-dinitrotoluene 100 Heptachlor 036 2,6-dinitrotoluene 101 Heptachlor ep oxide (BHC-hexachlorocyclohexane) 037 1,2-diphenylhydrazine 102 Alpha-BHC 038 Ethylbenzene 103 Beta-BHC 039 Fluoranthene 104 Gamma-BHC (lindane) 040 4-chlorophenyl phenyl ether 105 Delta- BHC (PCB-polychlorinated biphenyls)September 2010 NPDES Permit Writers’ Manual

C-2 Appendix C. Priority Pollutants Exhibit C-1 Priority pollutants from 40 CFR Part 423, Appendix A (continued)
# Pollutant name # Pollutant name 041 4-bromophenyl phenyl ether 106 PCB-1242 (Arochlor 1242) 042 Bis(2-chloroisopropyl) ether 107 PCB-1254 (Arochlor 1254) 043 Bis(2-chloroethoxy) methane 108 PCB-1221 (Arochlor 1221) 044 Methylene chloride (dichloromethane) 109 PCB-1232 (Arochlor 1232) 045 Methyl chloride (dichloromethane) 110 PCB-1248 (Arochlor 1248) 046 Methyl bromide (bromomethane) 111 PCB-1260 (Arochlor 1260) 047 Bromoform (tribromomethane) 112 PCB-1016 (Arochlor 1016) 048 Dichlorobromomethane 113 Toxaphene 051 Chlorodibromomethane 114 Antimony 052 Hexachlorobutadiene 115 Arsenic 053 Hexachloromyclopentadiene 116 Asbestos 054 Isophorone 117 Beryllium 055 Naphthalene 118 Cadmium 056 Nitrobenzene 119 Chromium 057 2-nitrophenol 120 Copper 058 4-nitrophenol 121 Cyanide, Total 059 2,4-dinitrophenol 122 Lead 060 4,6-dinitro-o-cresol 123 Mercury 061 N-nitrosodimethylamine 124 Nickel 062 N-nitrosodiphenylamine 125 Selenium 063 N-nitrosodi-n-propylamin 126 Silver 064 Pentachlorophenol 127 Thallium 065 Phenol 128 Zinc 066 Bis(2-ethylhexyl) phthalate 129 2,3,7, 8-tetrachloro-dibenzo-p-dioxin (TCDD)September 2010 NPDES Permit Writers’ Manual

Appendix D.

Appendix D. New Source Dates by Effluent Guideline Category D-1 

## Appendix D. New Source Da tes by Effluent Guideline Category

This appendix provides the applicable new source da tes 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 Dischargers 1

< www.epa.gov/npdes/pubs /newsource_dates.pdf > sent by the directors of EPA’s Water Permits Division and the Engineering and Analysis Division to the Regiona l Water Division Directors on September 28, 2006. Section 5.2.2.4 of this manual discusses the determin ation of whether existing or new source standards apply.
EPA has promulgated regulations under the Clean Wa ter Act (CWA) that establish effluent limitations guidelines for existing sources, standards of performan ce 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 secti on 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 di rect 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 sta ndard applicable to an indirect discharger.

Exhibit D-1 lists new source dates for direct or i ndirect 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 c onstruction 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 Sour ce date is the proposal date if the standard is finalized within 120 days after its proposa l; otherwise, the New Source date is the promulgation date

. EPA’s regulations establish the time and date of EP A’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 en sure 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 indir ect dischargers, by permits or equivalent controlSeptember 2010 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 Category New source date for direct dischargers New source date for indirect dischargers 467 Aluminum Forming Subparts A- F: 10/24/83 Subparts A-F: 11/22/82 427 Asbestos Manufacturing Subparts A-K: 10/30/73 2 Not Applicable 461 Battery Manufacturing Subparts A-G: 03/09/84 Subparts A-G 11/10/82

407 Canned and Preserved Fruits and Vegetables Processing Subparts A-H: 03/21/74 Not Applicable

408 Canned and Preserved Seafood Processing Subparts A-J, N: Subparts O-AG: 06/26/74 12/01/75 Not Applicable

458 Carbon Black Manufacturing Subparts A-D: 01/09/78 Subpar ts A-D: 05/18/76 411 Cement Manufacturing Subparts A-C: 02/20/74 Not Applicable

437 Centralized Waste Treatment (CWT) Subparts A-D: 01/05/01 Subparts A-D: 01/13/99

434 Coal Mining Subparts B-E, H: Subpart G: 05/04/84 3 02/22/02 4 Not Applicable

465 Coil Coating Subparts A-C: Subpart D: 12/01/82 11/17/83 Subparts A-C: Subpart D: 01/12/81 02/10/83

412 Concentrated Animal Feeding Operations (CAFO) Subparts A-B: Subparts C-D: 02/14/74 04/14/03 5 Subpart B: 09/07/73

451 Concentrated Aquatic Animal Production Subparts A-B: 09/07/04 Not Applicable

468 Copper Forming Subpart A: 08/15/83 Subpart A: 11/12/82

405 Dairy Products Processing Subpar ts A-L: 05/28/74 Not Applicable

469 Electrical and Electronic Components Subparts A-B: Subparts C-D: 04/08/83 12/14/83 Subparts A-B: Subparts C-D: 08/24/82 03/09/83 413 Electroplating Not Applicable 6 See Metal Finishing 7
457 Explosives Manufacturing Not Applicable Not Applicable 424 Ferroalloy Manufacturing Subparts A-C: 02/22/74 Not Applicable

418 Fertilizer Manufacturing Subparts A-D: Subpart E: Subparts F-G: 04/08/74 01/16/76 10/07/74 8 Subparts A-D 9 : Subpart E: Subparts F-G: 12/07/73 01/16/76 10/07/74

426 Glass Manufacturing Subpart A: Subparts B-D: Subparts E-G: Subparts H, J-M: 01/22/74 02/14/74 02/14/74 01/16/75 Subparts H, K-M: 08/21/74

406 Grain Mills Subparts A-J: 12/04/73 10 Subpart A: 12/04/73 454 Gum and Wood Chemicals Not Applicable Not Applicable 460 Hospitals Not Applicable Not Applicable 447 Ink Formulating Subpart A: 07/28/75 Subpart A: 02/26/75

D-2 Appendix D. New Source Dates by Effluent Guideline CategorySeptember 2010 NPDES Permit Writers’ Manual

Appendix D. New Source Dates by Effluent Guideline Category D-3 Exhibit D-1 New source dates by effluent category (continued)

40 CFR Part Category New source date for indirect dischargers New source date for direct dischargers

415 Inorganic Chemicals Subparts B-F, H, K-N, P, Q, T, V, W, AJ [CuSO 4 manufacturing], AH, AP, AU [NiSO 4 manufacturing], BB: Subparts AJ [except CuSO 4 manufacturing], AU [except NiSO 4 manufacturing], BL - BO: 06/29/82

08/22/84 Subparts B-F, H, K-N, P, Q, V, AH, AJ [CuSO 4 manufacturing], AP, AU [NiSO 4 manufacturing], BB: Subparts T, AA, AC, AE, AI, AJ [except CuSO 4 manufacturing], AL, AN, AQ, AR, AU [except NiSO 4 manufacturing], AX, BC, BH, BK-BO: 07/24/80

10/25/83

420 Iron and Steel Manufacturing Subparts A-B: Subpart C: Subpart D, Semi-Wet: Subpart D, Other: Subparts E-L: Subpart M: 11/18/02 11 05/27/82 10/31/02 05/27/82 05/27/82 10/31/02 Subparts A-B: Subpart C: Subpart D, Semi-Wet: Subpart D, Other: Subparts E-F, H-J,L: Subpart M: 11/18/02 12 01/07/81 12/27/00 01/07/81 01/07/81 12/27/00 445 Landfills Subparts A-B: 02/02/00 Not Applicable 425 Leather Tanning and Finishing Subparts A, B, D-I: Subpart C: 11/23/82 04/04/88 Subpart A, B, D-I: Subpart C: 07/02/79 01/21/87 432 Meat and Poultry Products Subparts A-D, Small Facilities: Subparts A-D, Other: Subparts E-I, Small Facilities: Subparts E-I, Other: Subpart J-L: 02/28/74 13 09/22/04

01/03/75 14 09/22/04 09/22/04 Not Applicable

433 Metal Finishing Subpart A: 07/15/83 Subpart A: 08/31/82 464 Metal Molding and Casting Subparts A-D: 11/13/85 Subpar ts A-D: 11/15/82 438 Metal Products and Machinery Subpart A: 06/12/03 15 Not Applicable

436 Mineral Mining and Processing Not Applicable Not Applicable

471 Nonferrous Metals Forming and Metal Powders Subparts A-J: 09/06/85 Subparts A-J: 03/05/84

421 Nonferrous Metal Manufacturing Subparts B-I (except molybdenum acid plants), K-M: Subparts N-AE, molybdenum acid plants in subpart I: Subpart J: 03/08/84

10/04/85 02/04/88 Subparts B-I (except molybdenum acid plants), K-M: Subparts N-AE, molybdenum acid plants in subpart I: Subpart J: 02/17/83

06/27/84 01/22/87

435 Oil and Gas Extraction 16 Subparts C (Onshore), D (Coastal), and E (Agriculture & Wildlife): Subparts A and D (Synthetic-Based Drilling Fluids): 03/04/93

02/05/01 Subpart D: 02/17/95

440 Ore Mining and Dressing Subparts A- F, J, M: 12/03/82 Not ApplicableSeptember 2010 NPDES Permit Writers’ Manual

D-4 Appendix D. New Source Dates by Effluent Guideline Category Exhibit D-1 New source dates by effluent category (continued)

40 CFR Part Category New source date for direct dischargers New source date for indirect dischargers 414 Organic Chemicals, Plastics, and Synthetic Fibers Subparts B-H: 11/19/87 Subparts B-H: 03/21/83

446 Paint Formulating Subpart A: 07/28/75 Subpart A: 02/26/75 443 Paving and Roofing Materials (Tars and Asphalt) Subparts A-D: 07/28/75 Subparts A-D: 01/10/75

455 Pesticide Chemicals Subparts A-B: Subparts C, E: 10/12/93 11/20/96 Subparts A-B: Subparts C, E: 04/10/92 04/14/94 419 Petroleum Refining Subparts A- E: 10/18/82 Subparts A-E: 12/21/79 439 Pharmaceutical Manufacturing Subparts A-D: 11/20/98 17 Subparts A-D: 05/02/95

422 Phosphate Manufacturing Subparts D-F: 06/23/76 Not Applicable 459 Photographic Not Applicable Not Applicable 463 Plastics Molding and Forming Subparts A-C: 12/17/84 Not Applicable

466 Porcelain Enameling Subparts A- D: 11/24/82 Subp arts A-D: 01/27/81 430 Pulp, Paper, and Paperboard Subparts B, E: Subparts A, C, D, F, G, I-L: 06/15/98 18

11/18/82 Subparts B, E: Subparts A, C, D, F, G, I-L: 12/17/93 01/06/81

428 Rubber Manufacturing Subparts A-D: Subparts E-J: 02/21/74 01/10/75 Subparts E-K: 08/23/74

417 Soap and Detergents Manufacturing Subparts A-S: 4/12/74 Subpart Q: Subparts O, P, R: 12/26/73 02/20/75 423 Steam Electric Power Generation 11/19/82 19 10/14/80

409 Sugar Processing Subpart A: Subparts B, C: 1/31/74 12/07/73 20 Not Applicable

1 Boornazian, 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. < www.epa.gov/npdes/pubs/newsource_dates.pdf >.

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 434.11(j)(1).

4 The New Source date is specified in 40 CFR 434.11(j)(1).

5 New Source date derived from the 10-year protec tion period [see 40 CFR 412.35(d) and 412.43(d)].

6 Direct dischargers formerly regu lated under Part 413 are now regulated under Part 433 (metal finishing).

7 Pretreatment categorical sta ndards in Part 413 currently apply only to job s hop electroplaters and inde pendent printed circuit board manufacturers that were in existence before the New Source date for Part 433 (metal fini shing). Job shop electroplaters a nd independent printed circuit board manufactur ers that are “New Sources” must comply with PSNS in Part 433. Except for these “existing” job shop electroplater s and independent printed circuit board manufactu rers, all other operati ons formerly subject t o 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).

Endnotes for this chapter continued on the next page.September 2010 NPDES Permit Writers’ Manual

Appendix D. New Source Dates by Effluent Guideline Category D-5 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 faci lities in Subpart s 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 in formation on the applicability of New Source standards.

17 New Source date derived from the 10-year protection period [see 40 CFR 439.15(c), 439.35(c), and 439.45(b)].

18 Date specified in 40 CFR 430.25(b) and 430.55(b). Refer to these sections for additiona l information regarding the applicability of NSPSs.

19 NSPS promulgated were not removed via th e 1982 regulation; therefore wastewaters ge nerated by Part 423-applicable sources that were New Sources under the 1974 regula tions are subject to the 1974 NSPS. The Ne w 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).