vvEPA
United States
Environmental Protection
Agency
Office Of Water
(4204)
EPA 832-B-95-008
September 1995
Combined Sewer Overflows
Guidance For Permit Writers
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EPA 832-B-95-008
For
Office of Wastewater Management
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC
August 1995
Recycled/Recyclable * Printed with Vegetable Based Inks on Recyeted Paper (20% Postconsumer)
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NOTICE
The statements in this document are intended solely as guidance. This document
is not intended, nor can it be relied on, to create any rights enforceable by any
party In litigation with the United States. EPA and State officials may decide to
follow the guidance provided in this document, or to act at variance with the
guidance, based on an analysis of specific site circumstances. This guidance may
be revised without public notice to reflect changes in EPA's strategy for
implementation of the Clean Water Act and its implementing regulations, or to
clarify and update the text.
Mention of trade names or commercial products in this document does not
constitute an endorsement or recommendation for use.
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460 "
OFFICE OF
WATER
MEMORANDUM
SUBJECT: CSO Guidance for Permit Writers
FROM: Michael B. Cook, Director (420
Office of Waste water Managem
TO: Interested Parties
1 am pleased to provide you with the Environmental Protection -\:cr,^\ % d.PA's)
guidance document for permit writers involved in developing National l\ '..^r.: D.icharge
Elimination System (NPDES) permits with Combined Sewer Overflow tC'Su. ..inJmons.
This docoment is one of several being prepared to foster implemeniatu>- t>: i S'A's CSO
Control Policy. The CSO Control Policy, issued on April 11, 1994, c/-:>;.. v.-s j rational
approach under the NPDES permit program for controlling discharges ;:,'. r » *:,,:u»n"s
waters from combined sewer systems.
To facilitate implementation of the CSO Control Policy, EPA i^ pr.-vr.r ; guidance
documents that can be used by NPDES permitting authorities, aft'eckv; - -* ..,;i..«,:ies, and
their consulting engineers in planning and implementing CSO control- n.,.- *., -Itimately
comply with the requirements of the Clean Water Act.
Specifically, this manual provides guidance to NPDES permitiir:; ^,.::;on:ies and
permit writers to develop and issue NPDES permits to control CSOs in a.,\»:o^.nje with the
expectations of the National CSO Control Policy. It recommends procedures ar.i! provides
example permit language that permit writers can use to develop defensible and enforceable
NPDES permit requirements. This guidance assumes the permit writer is responsible for
ensuring coordination and involvement with WQS authorities, enforcement authorities, the
public, and the permittee,
This guidance has been reviewed extensively within the Agency as well as by
municipal groups, environmental groups, and other CSO stakeholders, I am grateful to all
who participated in its preparation and review, and believe that it will further the
implementation of the CSO Control Policy.
If you have any questions regarding the manual or its distribution, please call Tony
Smith in the Office of Wastewater Management, at (202) 260-1017.
Pnraad ««Ui SoyiCs/wia W< en (taoot that
at toast 50% r»cyd«£f Rber
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TABLE OF
Page
1 INTRODUCTION , 1-1
1.1 BACKGROUND 1-1
1.2 HISTORY OF THE CSO CONTROL POLICY 1-1
1.3 KEY OF THE CSO CONTROL POLICY , 1-3
1.4 GUIDANCE TO SUPPORT IMPLEMENTATION OF THE CSO
CONTROL POLICY 1-6
1.5 PURPOSE OF MANUAL AND TARGET AUDIENCE , 1-6
1.6 ORGANIZATION OF MANUAL 1-7
2 INTRODUCTION TO CSO PERMITTING 2-1
2.1 OVERVIEW OF CSO PERMITTING APPROACH 2-1
2.2 RESPONSIBILITY OF PERMITTING AUTHORITIES 2-3
2.3 CSO PERMITTING AND WATERSHED
CONSIDERATIONS 2-4
2.4 MECHANISMS FOR REQUIRING CSO CONTROLS 2-5
2.5 COMPLEX COMBINED SYSTEMS 2-6
2.6 PREVIOUS OR ONGOING CSO CONTROL EFFORTS 2-9
2.7 COMBINED SYSTEMS IN SMALLER JURISDICTIONS .... 2-9
2.8 MEASURES OF SUCCESS 2-10
2.9 COORDINATION WITH STATE WATER QUALITY STANDARDS
AUTHORITY , 2-12
3 PHASE I PERMITTING 3-1
3.1 I 3-1
3.2 INFORMATION NEEDS 3-1
3.3 IDENTIFICATION OF CSO OUTFALLS IN THE 3-3
3,4 NINE MINIMUM CONTROLS 3-3
3.4.1 Implementation Considerations 3-6
3.4.2 Documentation and Reporting 3-9
3.5 LONG-TERM CONTROL PLAN 3-10
3.5.1 Components of the Long-Term Control Plan 3-13
3.5.1.1 Public Participation 3-14
3.5.1.2 Characterization, Monitoring, and Modeling of the
CSS and Receiving Waters 3-18
August 1995
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TABLE OF (Continued)
Page
3.5.1.3 Consideration of Sensitive Areas 3-19
3.5.1.4 Evaluation of Control Alternatives 3-20
3.5.1.5 Cost/Performance Considerations 3-26
3.5.1.6 Operational Plan , 3-27
3.5.1.7 Maximization of Treatment at the POTW Treatment
Plant 3-27
3.5.1.8 Implementation Schedule 3-28
3.5.1.9 Post-Construction Compliance Monitoring Program . . 3-29
3.5.2 Schedule for Development of the Long-Tenn Control Plan .... 3-30
3.5.3 Considerations for Previous or Ongoing CSO Control Efforts
and Small Combined Sewer Systems 3-32
3.5.3.1 Recognition of Previous or Ongoing Efforts at
Controlling CSOs ,...,". 3-32
3.5.3.2 Small System Considerations 3-34
3.6 EFFLUENT LIMITATIONS 3-34
3.6.1 Technology-Based Requirements 3-35
3.6.2 Water Quality-Based Requirements 3-36
3.7 MONITORING . 3-37
3.8 3-40
3.9 SPECIAL CONDITIONS 3-40
3.9.1 CSO-Related Bypass 3-40
3.9.2 Permit Reopener Clause 3-41
3.10 ADDITIONAL ACTIVITIES DURING PHASE I PERMITTING .... 3-41
4 PHASE H PERMITTING 4-1
4.1 PHASE II PERMIT PROCESS 4-1
4.2 INFORMATION 4-2
4.3 IDENTIFICATION OF CSO OUTFALLS IN THE PERMIT 4-3
4.4 NINE MINIMUM CONTROLS 4-3
4.4.1 Review of Permittee's Implementation of the Nine Minimum
Controls 4-4
4.4.1.1 Proper Operation and Regular Maintenance Programs
for the CSS and CSO Outfalls 4-5
4.4.1.2 Maximum Use of the Collection System for Storage ... 4-6
4.4.1.3 Review and Modification of Pretreatment Programs ... 4-6
4.4.1.4 Maximization of Flow to Publicly Owned Treatment
Works Treatment Plant . , 4-7
4.4.1.5 Prohibition of CSOs During Dry Weather Flow
Conditions 4-7
ii August 1995
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OF CONTENTS (Continued)
Page
4.4.1.6 Control of Solid and Floatable Materials in CSOs .... 4-8
4.4.1.7 Pollution Prevention Program 4-8
4.4.1.8 Public Notification 4-9
4.4.1.9 Monitoring to Effectively Characterize CSO Impacts
and Efficacy of CSO Controls 4-9
4.4.2 Permit Conditions 4-10
4.4.2.1 Documentation for Fact Sheet/Statement of Basis .... 4-14
4.5 LONG-TERM CONTROL PLAN 4-14
4.5.1 Review of Long-Tenn Control Plan 4-15
4.5.1.1 Public Participation 4-17
4.5.1.2 CSS Characterization, Monitoring, and Modeling .... 4-17
4.5.1.3 CSO Control Alternatives . 4-19
4.5.1.4 Selected CSO Controls 4-19
4.5.1.5 Implementation Schedule 4-20
4.5.1.6 Operational Plan 4-21
4.5.1.7 Post-Construction Compliance Monitoring 4-22
4.5.2 Implementation of the Long-Term Control Plan 4-22
4.5.2.1 Selected CSO Controls 4-23
4.5.2,2 Operational Plan 4-24
4.5.2.3 Post-Construction Compliance Monitoring 4-25
4.5.2.4 Documentation for Fact Sheet/Statement of Basis .... 4-25
4.6 EFFLUENT LIMITATIONS 4-26
4.6.1 Technology-Based Requirements 4-26
4.6.2 Water Quality-Based Requirements . 4-26
4.6.2.1 Presumption Approach 4-28
4.6,2.2 Demonstration Approach 4-29
4.7 MONITORING 4-30
4.8 REPORTING . 4-33
4.9 SPECIAL CONDITIONS 4-34
4.9.1 CSO-Related Bypass 4-34
4.9.2 Reassessment of Sensitive Areas 4-37
4,9.3 Permit Reopener Clause 4-38
5 POST-PHASE II PERMITTING 5-1
5.1 CONTINUATION OF II 5-1
5.2 SUBSEQUENT CSO PERMITTING 5-2
iii August 1995
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TABLE OF CONTENTS (Continued)
Page
APPENDIX A COMPILATION OF EXAMPLE CSO PERMIT CONDITIONS A-l
APPENDIX B DEVELOPMENT AND REVIEW OF MONITORING AND MODELING
PLAN B-l
APPENDIX C SUGGESTED NINE MINIMUM CONTROLS EVALUATION
CHECKLIST C-l
APPENDIX D SUGGESTED LONG-TERM CONTROL PLAN EVALUATION
CHECKLIST D-l
GLOSSARY G-l
REFERENCES R-l
iv August 1995
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LIST OF
Page
Exhibit 1-1. Roles and Responsibilities 1-5
Exhibit 2-1. Categories of CSO Permitting Conditions 2-7
Exhibit 3-1. Example Permit Language for Identifying CSO Outfalls in the Phase I
Permit 3-3
Exhibit 3-2. Summary of the Nine Minimum Controls 3-5
Exhibit 3-3. Example Permit Language to Require Immediate Implementation of the
Nine Minimum Controls 3-7
Exhibit 3-4. Example Permit Language for Requiring Documentation and Reporting
of the Nine Minimum Controls 3-10
Exhibit 3-5. Example Types of NMC Documentation 3-11
Exhibit 3-6. Example Permit Language for Requiring the Development of a Long-
Term Control Plan *! 3-15
Exhibit 3-7. Sensitive Areas Identified in the CSO Control Policy . 3-19
Exhibit 3-8. Example Permit Language for Requiring Compliance with Narrative
Water Quality Standards 3-37
Exhibit 3-9. Example Permit Language for a Phase I Reopener Clause 3-41
Exhibit 4-1. Example Permit Language for Identifying CSO Outfalls in a Phase II
Permit 4-3
Exhibit 4-2. Example Permit Language for Continued Implementation of the Nine
Minimum Controls • 4-11
Exhibit 4-3. Example Permit Language for Implementing Selected CSO Controls . . . 4-25
Exhibit 4-4. Example Permit Language for Performance Standards for the
Presumption Approach 4-29
Exhibit 4-5. Example Permit Language for Site-Specific Monitoring Activities .... 4-32
Exhibit 4-6. Example Permit Language for Requiring Submission of Progress
Reports 4-33
Exhibit 4-7. Example Permit Language for a CSO-Related Bypass 4-37
Exhibit 4-8. Example Permit Language for Sensitive Area Reassessment 4-38
Exhibit 4-9. Example Permit Language for Reopener Clauses 4-39
August 1995
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CHAPTER 1
INTRODUCTION
1.1
Combined sewer systems (CSSs) are wastewater collection systems designed to cany
sanitary sewage (consisting of domestic, commercial, and industrial wastewater) and storm water
(surface drainage from rainfall or snowmelt) in a single pipe to a treatment facility. CSSs serve
about 43 million people in approximately 1,100 communities nationwide. Most of these
communities are located in the Northeast and Great Lakes regions. During dry weather, CSSs
convey domestic, commercial, and industrial wastewater. In periods of rainfall or snowmelt,
total wastewater flows can exceed the capacity of the CSS and/or treatment facilities. When this
occurs, the CSS is designed to overflow directly to surface water bodies, such as lakes, rivers,
estuaries, or coastal waters. These overflows—called combined sewer overflows (CSOs)—can
be a major source of water pollution in communities served by CSSs.
Because CSOs contain untreated domestic, commercial, and industrial wastes, as well as
surface runoff, many different rypes of contaminants can be present. Contaminants may include
pathogens, oxygen-demanding pollutants, suspended solids, nutrients, toxics, and floatable
matter. Because of these contaminants and the volume of the flows, CSOs can cause a variety
of adverse impacts on the physical characteristics of surface water, impair the viability of aquatic
habitats, and pose a potential threat to drinking water supplies. CSOs have been shown to be
a major contributor to use impairment and aesthetic degradation in many receiving waters and
have contributed to shellfish harvesting restrictions, beach closures, and even occasional fish
kills.
1.2 OF THE CSO CONTROL POLICY
Historically, the control of CSOs has proven to be extremely complex. This complexity
stems partly from the difficulty in quantifying CSO impacts on receiving water quality and the
site-specific variability in the volume, frequency, and characteristics of CSOs. In addition, the
financial considerations for communities with CSOs can be significant. The U.S. Environmental
1-1 " August 1995
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Chapter 1 Introduction
Protection Agency (EPA) estimates the CSO abatement costs for the 1,100 communities served
by CSSs to be approximately $41.2 billion.
To address these challenges, EPA's Office of Water issued a National Combined Sewer
Overflow Control Strategy on August 10, 1989 (54 Federal Register 37370). This Strategy
reaffirmed that CSOs are point source discharges subject to National Pollutant Discharge
Elimination System (NPDES) permit requirements and to Clean Water Act (CWA) requirements.
The CSO Strategy recommended that all CSOs be identified and categorized according to their
status of compliance with these requirements. It also set forth three objectives:
* Ensure that if CSOs occur, they are only as a result of wet weather
• Bring all wet weather CSO discharge points into compliance with the technology-
based and water quality-based requirements of the CWA
* Minimize the impacts of CSOs on water quality, aquatic biota, and human health.
In addition, the CSO Strategy charged all States with developing state-wide permitting strategies
designed to reduce, eliminate, or control CSOs.
Although the CSO Strategy was successful in focusing increased attention on CSOs, it
fell short in resolving many fundamental issues. In mid-1991, EPA initiated a process to
accelerate implementation of the Strategy. The process included negotiations with
representatives of the regulated community. State regulatory agencies, and environmental groups.
These negotiations were conducted through the Office of Water Management Advisory Group.
The initiative resulted in the development of a CSO Control Policy, which was published in the
Federal Register on April 19, 1994 (59 Federal Register 18688).
1-2 August 1995
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Chapter 1 Introduction
The intent of the CSO Control Policy is to:
8 Provide guidance to permittees with CSOs, NPDES permitting and enforcement
authorities, and State water quality standards (WQS) authorities
* Ensure coordination among the appropriate parties in planning, selecting, designing,
and implementing CSO management practices and controls to meet the requirements
of the CWA
• Ensure public involvement during the decision-making process,
The CSO Control Policy contains provisions for developing appropriate, site-specific
NPDES permit requirements for all CSSs that overflow due to wet weather events. It also
announces an enforcement initiative that requires the immediate elimination of overflows that
occur during dry weather and ensures that the remaining CWA requirements are complied with
as soon as possible.
1.3 KEY OF CSO CONTROL POLICY
The CSO Control Policy contains four key principles to ensure that CSO controls are
cost-effective and meet the requirements of the CWA:
• Provide clear levels of control that would be presumed to meet appropriate health and
environmental objectives
* Provide sufficient flexibility to municipalities, especially those that are financially
disadvantaged, to consider the site-specific nature of CSOs and to determine the most
cost-effective means of reducing pollutants and meeting CWA objectives and
requirements
* Allow a phased approach for implementation of CSO controls considering a
community's financial capability
* Review and revise, as appropriate, WQS and their implementation procedures when
developing long-term CSO control plans to reflect the site-specific wet weather
impacts of CSOs.
1-3 August 1995
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Chapter 1 Introduction
In addition, the CSO Control Policy clearly defines expectations for permittees, State
WQS authorities, and NPDES permitting and enforcement authorities. These expectations
include the following:
• Permittees should immediately implement the nine minimum controls (NMC), which
are technology-based actions or measures designed to reduce CSOs and their effects
on receiving water quality, as soon as practicable but no later than January 1, 1997,
• Permittees should give priority to environmentally sensitive areas,
• Permittees should develop long-term control plans (LTCPs) for controlling CSOs.
A permittee may use one of two approaches: 1) demonstrate that its plan is adequate
to meet the water quality-based requirements of tie CWA ("demonstration
approach"), or 2) implement a minimum level of treatment (e.g., primary
clarification of at least 85 percent of the collected combined sewage flows) that is
presumed to meet the water quality-based requirements of the CWA, unless data
indicate otherwise ("presumption approach"),
* WQS authorities should review and revise, as appropriate. State WQS during the
CSO long-term planning process.
• NPDES permitting authorities should consider the financial capability of permittees
when reviewing CSO control plans.
Exhibit 1-1 illustrates the roles and responsibilities of permittees, NPDES permitting and
enforcement authorities, and State WQS authorities.
In addition to these key elements and expectations, the CSO Control Policy also addresses
important issues such as ongoing or completed CSO control projects, public participation, small
communities, and watershed planning.
1-4 August 1995
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Exhibit 1-1. Roles and Responsibilities
Permittee
NPDES Permitting Authority
NPDES Enforcement Authority
State WQS Authorities
* Evaluate and implement NMC
» Submit documentation of NMC
implementation hy January 1,
1997
* Develop LTCP and submit for
review to NPDIiS permitting
authority
• Support the review of WQS in
CSO-impacted receiving wafer
bodies
• Comply with permit conditions
hascd on narrative WQS
* Implement selected CSO controls
from LTCP
* Perform post-construction
compliance monitoring
• Reassess overflows to sensitive
areas
* Coordinate alt activities with
NPDBS permitting authority.
State WQS authority, and Slate
watershed personnel
* Reassess/revise CSO permitting
strategy
* Incorporate into Phase i permits
CSO related conditions (e.g., NMC
implementation and documentation
and LTCP development)
« Review documentation of NMC
implementation
* Coordinate review of LTCP
components throughout the LTCP
development process and
accept/approve permittee's LTCP
* Coordinate the review and revision
of WQS as appropriate
« Incorporate into Phase II permits
CSO-related conditions (e.g.,
continued NMC implementation and
LTCP implementation)
* Incorporate implementation schedule
into an approptiate en
mech.tniMn
if p *rH >r t
* Ensure that CSO requirements and
schedules for compliance are
" incorporated into appropriate
enforceable mechanisms
9 Monitor adherence to January I,
1997, deadline for NMC
implementation and documentation
• Take appropriate enforcement action
against dry weather overflows
» Monitor compliance with Phase I,
Phase II, and post-Phase II permits
and take enforcement action as
appropriate
* Review WQS in CSG-impacted
receiving water bodies
• Coordinate review with LTCP
development
* Revise WQS as appropriate:
Development of site-specific
criteria
Modification of designated use to
- Create partial use reflecting
specific situations
- Define use more explicitly
Temporary variance from WQS
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Chapter 1 Introduction
1.4 GUIDANCE TO IMPLEMENTATION OF THE CSO CONTROL
POLICY
To help permittees and NPDES permitting and WQS authorities implement the provisions
of the CSO Control Policy, EPA is developing the following guidance documents:
• Combined Sewer Overflows—Guidance for Long-Term Control Plan (EPA, 1995a)
(EPA 832-B-9S-002)
* Combined Se\ver Overflows—Guidance for Nine Minimum Controls (EPA, 1995b)
(EPA 832-B-95-GG3)
• Combined Sewer Overflows—Guidance for Screening and Ranking (EPA, 1995c)
(EPA 832-B-95-Q04)
• Combined Sewer Overflows—Guidance for Monitoring and Modeling (EPA, 1995d)
(EPA 832-B-95-OOS)
* Combined Sewer Overflows—Guidance far Financial Capability Assessment
(EPA, 1995e) (EPA 832-B-95-006)
• Combined Sewer Overflows—Guidance for Funding Options (EPA, 1995f) (EPA
832-B-95-Q07)
? Combined Sewer Overflows—Guidance for Permit Writers (EPA, 1995g) (EPA
832-B-95-008)
• Combined Sewer Overflows—Questions and Answers on Water Quality Standards and
the CSO Program (EPA, 1995h) (EPA 832-B-95-Q09),
1.5 OF MANUAL AND TARGET AUDIENCE
This manual provides guidance to NPDES permitting authorities and permit writers on
developing and issuing NPDES permits to control CSOs in accordance with the expectations of
the CSO Control Policy. Whenever possible, the manual translates the CSO Control Policy into
instructions, procedures, and example permit language that permit writers can use to develop
defensible and enforceable NPDES permit requirements. The document emphasizes the role of
the permit writer as the facilitator and coordinator of the CSO control program in achieving
compliance with the CWA, including attainment of WQS. This guidance assumes the permit
1-6 August 1995
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Introduction
writer is responsible for ensuring coordination and involvement with WQS authorities,
enforcement authorities, the public, and the permittee.
This manual is designed to be used by EPA and State NPDES permit writers who possess
a working knowledge of the CWA and NPDES permit regulations and requirements to control
point source discharges. Therefore, it provides guidance only for developing CSO-related permit
conditions; it does not provide the more general information available in other NPDES permit
guidance manuals, such as the training manual for NPDES permit writers. In addition, this
manual does not provide technical guidance on the operation of CSSs and the control of CSOs,
Information on these topics is contained in other CSO guidance manuals. EPA recommends that
the permit writer obtain all of the CSO guidance manuals listed previously and use them in
conjunction with this manual during the development and issuance of permits.
1,6 ORGANIZATION OF MANUAL
Chapter 2 presents an overview of the approach to CSO permitting as envisioned by the
CSO Control Policy. The chapter explains the responsibilities of NPDES permitting authorities,
setting of permitting priorities, and various strategies available to EPA Regions and States for
ensuring that the CSO Control Policy objectives are met. Chapter 3 presents guidance on and
example permit language for developing initial (Phase I) permit requirements for implementing
minimum technology-based control measures and initiating the development of long-term plans
for CSO controls. Chapter 4 provides the procedures, requirements, and example permit
language for the second round (Phase U) of CSO permits, which implement the selected long-
term CSO control measures. Chapter 5 discusses the development of post-Phase II permit
requirements, including completion of the construction and implementation of the long-term CSO
controls, as well as post-construction monitoring. The manual concludes with appendices,
including a compilation of example CSO permit conditions and suggested checklists for
evaluating the NMC and LTCP.
1-7 August 1995
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CHAPTER 2
INTRODUCTION TO CSO
The Combined Sewer Overflow (CSO) Control Policy provides a national strategy for
the control of CSOs. It presents a uniform, nationally consistent permitting approach that
should, for the first time, result in the establishment of both technology-based and water quality-
based requirements for all CSOs. Although the permitting approach envisioned for CSOs still
fits into the regulatory structure of the National Pollutant Discharge Elimination System
(NPDES) program at 40 CFR Part 122 and is similar to the permitting approach that most
NPDES permit writers are familiar with and have routinely employed for other point source
discharges, it is unlike the conventional NPDES permitting approach in many ways. This
chapter is designed to provide the permit writer with a clear understanding of the approach for
controlling CSOs that is envisioned by the CSO Control Policy. The remainder of this guidance
manual is designed to provide the permit writer with a more detailed understanding of how to
integrate CSO controls into the NPDES permitting process.
2.1 OVERVIEW OF CSO
The CSO Control Policy envisions that CSO control requirements typically will be
implemented through NPDES permits. Generally, NPDES permits include both technology-
based and water quality-based effluent limitations. In the absence of national effluent guidelines
for CSOs, the CSO Control Policy envisions that technology-based controls (i.e., best available
technology economically achievable/best conventional pollutant control technology) will be
established on a case-by-case basis using the permit writer's best professional judgment (BPJ)
and be expressed in the form of best management practices. The technology-based controls will
include, at a minimum, the nine minimum controls (NMC) as determined on a BPJ basis by the
NPDES permitting authority. In addition, the CSO Control Policy recommends that, initially,
water quality-based effluent limits be expressed in the form of narrative requirements and
performance-based standards for the combined sewer system (CSS). Ultimately, the water
quality-based effluent limits may also be expressed as numeric effluent limits when data are
sufficient to support their development.
2-1 August 1995
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Chapter 2 Introduction to CSO Permitting
The CSO Control Policy expects that CSO controls will be incorporated into NPDES
permits in a two-phased process. A Phase I permit will require the permittee to implement the
NMC, which are technology-based effluent limits as determined on a BPJ basis, and to document
that this requirement has been met. The Phase I permit will also require the permittee to
develop a long-term control plan (LTCP). The U.S. Environmental Protection Agency (EPA)
expects that implementation of the NMC during Phase I will achieve an interim level of CSO
control during the time the permittee is developing an LTCP. EPA expects that Phase I permit
requirements will be included in NPDES permits, either as permits become due for reissuance
during the usual NPDES permitting cycle or. where appropriate, on an accelerated schedule
through the permit modification process.
The Phase II permit typically will be the next permit issued after the Phase I permit. In
Phase II, the permittee will be required to implement the CSO controls identified in the LTCP.
Typically, water quality-based controls will be expressed as performance standards, and
technology-based controls will be the NMC, which may be refined to reflect site-specific
conditions. Whereas Phase I typically continues for only one permitting cycle. Phase II might
continue for several cycles until all selected CSO controls identified in the LTCP have been
constructed and implemented.
Although the two-phased approach may be appropriate if a permittee has not implemented
any CSO controls, in many instances, the separation between permit phases may not be distinct
and permits may contain both Phase I and Phase II elements. For example, a permittee may
have already evaluated and selected CSO controls for a portion of its CSS but not evaluated and
implemented the appropriate NMC. Thus, the next permit may include the Phase I requirement
to evaluate, implement, and document the implementation of the NMC and may also include a
Phase II requirement to implement the selected CSO controls. The CSO Control Policy is
designed to accommodate these variations in the development and implementation of CSO
control programs.
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Cfegpter'2 Introduction to CSO Permitting
After the selected CSO controls have been implemented, the NPDES permitting authority
should Issue the post-Phase II permit. This permit should generally contain requirements to
continue NMC implementation, properly operate and maintain the completed CSO controls in
accordance with the operational plan, and implement the post-construction monitoring program.
2,2 OF
The permit writer plays a critical role in the CSO permitting process, one that differs
from the NPDES permit writer's traditional role in several important aspects. First, the permit
writer plays a coordination role comparable to that of a team leader. In setting permitting
priorities and facilitating the development of CSO permit requirements, the permit writer has the
opportunity to develop a broad base of support for the CSO planning process and proposed CSO
controls. The permit writer should serve as the focal point for coordination with State WQS
authorities and should also work with enforcement authorities, as appropriate, to incorporate
compliance schedules into enforceable mechanisms. The permit writer will also coordinate with
local agencies, environmental groups, and other interested or CSO-affected members of the
public.
The second difference is that the CSO permit writer's role is ongoing. Even after the
issuance of the Phase I permit, the permit writer should continuously review interim LTCP
deliverables and other submissions, participating in the ongoing consensus-building process, and
developing and preparing for the issuance of Phase II permits.
The permit writer may also be able to assist communities in coordinating aspects of their
CSO control programs with each other. This might be particularly beneficial for adjacent small
communities discharging to the same receiving water. These communities might save significant
resources by coordinating the characterization of their sewer systems and monitoriBg of the CSO
impacts on the receiving water quality rather than pursuing these activities independently. The
permit writer may encourage community coordination by advising adjacent communities of their
mutual interests and opportunities for coordination.
2-3 August 1995
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Introduction to CSO
2.3 CSO AND
In response to the 1989 EPA National Combined Sewer Overflow Control Strategy, 30
States have received approval or conditional approval for CSO permitting strategies. These
strategies usually provided a priority-setting plan for CSOs. EPA expects States to evaluate the
need to revise their CSO strategies for consistency with the 1994 CSO Control Policy. This
represents an opportunity for NPDES permitting authorities to reconsider their CSO permitting
priorities in light of current or suspected environmental impacts, watershed permitting initiatives,
and other factors. States and EPA Regions should review these strategies and establish
appropriate permitting priorities for implementation of the CSO Control Policy.
In establishing CSO permitting priorities, the NPDES permitting authority should
consider factors such as the environmental impacts of CSOs (e.g. , beach closings, human health
hazards, and potential risk to endangered species). The NPDES permitting authority should also
consider requiring immediate action for CSOs to areas that meet the CSO Control Policy's
definition of "sensitive areas," To assist NPDES permitting authorities in establishing CSO
permitting priorities consistent with the CSO Control Policy, EPA developed the Combined
Sewer Overflows—Guidance for Screening and Ranking (EPA, 1995c). This document provides
guidance on establishing permitting priorities for CSSs and provides permittees with a tool for
prioritizing individual CSOs within their CSSs to allow for effective allocation of resources.
EPA encourages States to use a watershed approach to set permitting priorities. Under
a watershed approach, all surface water, ground water, and habitat stressors within a
geographically defined area are understood and addressed hi a coordinated fashion, as an
alternative to addressing individual pollutant sources in isolation. To support States that want
to implement a comprehensive statewide watershed approach, the Office of Water has developed
guidance and training designed to assist communities and natural resource agencies that are
pursuing a watershed approach. One part of this effort is the release of the NPDES Watershed
Strategy. This Strategy encourages NPDES permitting authorities to evaluate water pollution
control needs on a watershed basis and to coordinate CSO control program efforts with other
point and nonpoint source activities within the watershed.
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Chapter 2 Introduction to CSO Permitting
Applying a watershed approach to the CSO control program is particularly timely and
appropriate since an ultimate goal of the CSO Control Policy is development of long-term CSO
controls that will provide for the attainment of WQS. Since pollution sources other than CSOs
are likely to be contributing to the receiving water and affecting whether WQS are achieved, the
NPDES permitting authority needs to consider and understand these other sources.
Total maximum daily loads (TMDLs) provide the basis of equitably allocating cost-
effective controls on a watershed basis. By examining the contribution of both point and
nonpoint sources, the TMDL process ensures better use of limited resources in achieving WQS.
To assist in the development of TMDLs for episodic, wet-weather events, EPA plans to publish
technical guidance for estimating TMDLs that address integration of steady state and episodic
point and nonpoint sources.
2.4 MECHANISMS FOR CSO CONTROLS
The CSO Control Policy envisions that, in most cases, CSO requirements and controls
will be incorporated into a municipality's existing NPDES permit for its discharge from the
publicly owned treatment works (POTW), much like the incorporation of pretreatment and
sewage sludge requirements. CSO conditions may be incorporated into the NPDES permit in
several ways: 1) by including the conditions hi the permit during the next five-year permit
renewal cycle, 2) by modifying the permit for cause in accordance with the criteria in 40 CFR
122.62(a) or (b) (most likely through a major permit modification), or 3) by revoking and
reissuing the permit for cause in accordance with the criteria in 40 CFR 122.62(b). EPA
assumes that, in most cases, CSO conditions will be incorporated into NPDES permits through
permit expiration and reissuance during the five-year permit cycle, (This document assumes this
scenario for illustrative purposes.) Unless the permit writer intends to incorporate CSO
conditions into an NPDES permit immediately, the permit writer should inform affected parties
of the impending changes and encourage them to take steps to implement the CSO Control
Policy recommendations, especially the NMC. voluntarily.
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Chapter 2 Introduction to CSO Permitting
EPA recommends that the permit writer integrate CSO conditions into an existing NPDES
permit in one of two ways. The CSO conditions can be grouped together and contained in a
separate section of she NPDES permit the same way that sewage sludge or pretreatment
requirements are often placed in a separate section. Appendix A illustrates how CSO conditions
can be grouped together in a separate section of an NPDES permit. Alternately, individual CSO
conditions can be integrated into separate sections of the NPDES permit. For example, CSO
conditions can be integrated into the effluent limitations, monitoring requirements, and special
conditions sections of the permit, as appropriate. Exhibit 2-1 contains an overview of the
categories of CSO permitting conditions, which are discussed throughout the manual.
Other tools are available to the NPDES permitting authority in cases where the NPDES
permit is not the appropriate mechanism to initiate or require CSO control. In some cases, it
might be necessary for the NPDES permitting authority to include the CSO conditions in an
appropriate enforceable mechanism. An enforceable order can be issued, either independently
or in conjunction with an NPDES permit, when a permittee cannot comply immediately with the
terms of the NPDES permit and compliance dates have passed. For example, an enforceable
order that requires compliance with the NMC (and submittal of appropriate documentation) no
later than January 1, 1997, might be necessary in cases where immediate compliance cannot be
achieved.
In addition, the NPDES permitting authority may request information on a community's
CSS under Section 308 of the Clean Water Act (CWA) (or State equivalent). Much of the
example NPDES permit language can be incorporated into a Section 308 information request.
2.5
In the most common and simple case, a single system-wide permit is issued for all CSO
outfalls from a single authority. For example, a municipality or a small sanitary,sewer authority
with one POTW treatment plant should be issued one NPDES permit that addresses requirements
for the POTW, as well as for CSOs, storm water, sewage sludge, and a pretreatment program,
as appropriate.
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Exhibit 2-1. Categories of CSO Permitting Conditions
TIME
Years after Phase I Permit Issuance
NPDES Permit Requirement
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 + performance-based
standards
« Narrative + performance-based
standards 4- numeric water
quality-based cffluent limits (as
appropriate)
C. Monitoring
* Characterization, monitoring.
and modeling of CSS
* Monitoring to evaluate water
quality impacts
* Monitoring to determine
effectiveness of CSO controls
Post-cons!ruction compliance
monitoring
D. Reporting
» Documentation of NMC
implementation
* Interim LTCP deliverables
Implementation of CSO controls
Report results of post-
construction compliance
monitoring
E. Special Conditions
» Prohibition of dry weather
overflows (DWO)
• Development of LTCP
* Prohibition of DWO
* Implementation of LTCP
* Reopener clause for WQS
violations
* Sensitive area reassessment
» Prohibition of DWO
* Reopener clause for WQS
violations
-------
Chapter 2 to CSO
If a large municipality or sewerage control authority owns and/or operates two or more
POTW treatment plants served by CSSs (also owned by the municipality) and each has its
own NPDES permit, the NPDES permits generally should require an integrated and
comprehensive approach to CSO control. This is similar to integrated requirements for a
system-wide pretreatment program, where one municipality owns several POTW treatment
plants. Each permit should be renewed, modified, or revoked and reissued to include CSO
conditions. For example, if a municipality has three POTW treatment plants with individual
permits that will be renewed in different years (e.g., plant A's permit will be renewed
in 1995, B's permit will be renewed in 1996, and C's permit will be renewed in 1997),
conditions addressing all CSOs can. be incorporated into each permit upon renewal. To begin
the LTCP development process without having to wait for all of the permits to be reissued,
treatment plant A's permit should address CSOs within the entire jurisdictional boundaries,
including the areas discharging to treatment plant B and treatment plant C, and should require
development of an LTCP for the entire system. Correspondingly, the NPDES permits for
treatment plant B and plant C should contain the requirements. As an alternative
in this same situation, the permit writer may choose to incorporate aO conditions addressing
CSOs only into the first permit to be reissued (i.e., treatment plant A's permit). Incorporating
the CSO conditions into only one permit can preclude any confusion or inconsistencies resulting
from including the conditions in several different permits.
In some cases, different parts of a CSS, as well as the treatment plant, might be owned
or operated by different sewerage control authorities. In this situation, the permit writer may
issue each authority its own permit,'containing CSO conditions applicable to the portion of the
CSS owned or operated by that authority. The permits should require synchronization,
coordinated preparation, and implementation of CSO controls among all authorities within the
CSS. Each authority should be responsible for its collection system and CSOs and should
cooperate with the treatment plant permittee receiving the flows from the CSS. If a CSS is
permitted separately from the treatment plant, the fact sheets for the different permits should
cross reference each other for informational purposes. Alternately, the permit writer can issue
2-8 August 1995
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Chapter 2 Introduction to CSO Permitting
a single permit to all co-permittees, incorporating CSO conditions unique to each CSS and
treatment plant. Such co-permittee arrangements are subject to consent by the respective
co-permittees,
2.6 OR ONGOING CSO CONTROL
Some permittees might have already completed portions of the CSO control planning and
implementation process. The CSO Control Policy recognizes these ongoing CSO control efforts
and does not expect duplication of effort. If the permittee has 1) completed or substantially
completed construction of CSO control facilities that are designed to meet the water quality-
based requirements of the CWA, 2) substantially developed or is implement in*: a CSO control
program pursuant to an existing permit or enforcement order, and such program is considered
by the NPDES permitting agency to be adequate to meet the water qualt:> ha-^-d requirements
of the CWA, or 3) has previously constructed CSO control facilities in an eft -~ i.« comply with
water quality-based requirements of the CWA but has failed to comph JJK ; remaining CSOs,
the permit writer should take these efforts into account in determmin.- »r ..f. nf the LTCP
elements are still appropriate and consistent with the goals of the rv > ( <;urol Policy,
However, such a permittee would still be expected to develop an LTCP V,:, •:, ~< 5 3 presents
additional discussion of ongoing efforts.
2.7 IN JURISDICTIONS
The CSO Control Policy recognizes that the development and implementation of a
comprehensive LTCP might be difficult or inappropriate for some small municipalities. At the
discretion of the permit writer, jurisdictions with total populations under ~5,UX) may not need
to complete all of the formal steps involved in developing an LTCP. Certain provisions of the
CSO Control Policy should not be waived, however, such as implementation of the NMC, public
participation under the LTCP, and sensitive area considerations. Although the CSO Control
Policy is intended to provide some relief for small municipalities, the permit writer should
discuss the scope of the LTCP with the penniEee and the WQS authority to ensure that the
LTCP includes sufficient information to select appropriate CSO controls. Section 3.5.3
discusses considerations for smaller jurisdictions in greater detail.
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Chapter 2 Introduction to CSO Permitting
2,8 OF
As municipalities, NPDES permitting authorities, and the public embark on a coordinated
effort to address CSOs, serious considerations should be given to "measures of success." For
purposes of this discussion, measures of success are objective, measurable, and quantifiable
indicators that illustrate trends and results over time. Measures of success generally fall into
four categories:
• Administrative measures that track programmatic activities;
• End-of-pipe measures that show trends in the discharge of CSS flows to the receiving
water body, such as reduction of pollutant loadings, the frequency of CSOs, and the
duration of CSOs;
• Receiving water body measures that show trends of the conditions in the water body
to which the CSO occurs, such as trends in dissolved oxygen levels and sediment
oxygen demand; and
• Ecological, human health, and use measures that show trends in conditions relating
to the use of the water body, its effect on the health of the population that uses the
water body, and the health of the organisms that reside in the water body, including
beach closures, attainment of designated uses, habitat improvements, and fish
consumption advisories,
EPA's experience has shown that measures of success should include a balanced mix of
measures from each of me four categories.
As municipalities begin to collect data and information on CSOs and CSO impacts, they
have an important opportunity to establish a solid understanding of the "baseline" conditions and
to consider what information and data are necessary to evaluate and demonstrate the results of
CSO control. Municipalities and NPDES permitting authorities should agree early in the
planning stages on the data and information that will be used to measure success and on the
extent to which the permit and monitoring plan should include such indicators.
The following list presents examples of potential measures of success for CSO control,
organized by the four categories discussed above:
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Chapter 2 Introduction to CSO Permitting
* Administrative measures:
Number of NPDES permits or other enforceable mechanisms requiring
implementation of the NMC
Number of NPDES permits or other enforceable mechanisms issued requiring
development of LTCPs
Number of municipalities meeting technology-based requirements in permits
Number of municipalities meeting water quality-based requirements in permits
Compliance rates with CSO requirements in permits
Dollars spent/committed for CSO control measures
Nature and extent of CSO controls constructed/implemented.
• End-of-pipe measures:
Number of dry weather overflows eliminated
Number of CSO outfalls eliminated
Reduction in frequency of CSOs
Reduction in volume of CSOs
Reduction in pollutant loadings (conventional and toxics) in CSOs.
• Receiving water body measures:
Reduced in-stream concentrations of pollutants
Attainment of narrative or numeric water quality criteria.
* Ecological, human health, and use measures:
Improved access to water resources
• - Reduced flooding and drainage problems
Reduced costs and treatment of drinking water
- Economic benefits (e.g., value of increased tourism, value of shellfish harvested
from beds previously closed)
Restored habitat
Improved biodiversity indices
Reduction in beach closures
Reduction in fish consumption advisories.
(Note: These measures are included as examples only; EPA is supporting the
development of national measures of success for CSOs through a cooperative agreement
with the Association of Metropolitan Sewerage Agencies (AMSA). The results of
AMSA's efforts are expected to be available in late 1995.)
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Chapter 2 Introduction to CSO Permitting
When establishing CSO measures of success, municipalities and NPDES permitting
authorities should consider a number of important factors:
• Data quality and reproducibility—Can consistent and comparable data be collected
that allow for comparison over time (e.g., trend analysis) and from different sources
(e.g., watershed analysis)? Do standard data collection procedures exist?
• Costs—What is the cost of collecting and analyzing the information?
• Comprehenslbility to the public—Will the public understand and agree with the
measures?
• Availability—Is it reasonably feasible for the data to be collected'*
• Objectivity—Would different individuals evaluate the data or inh»rmauon similarly,
free from bias or subjectivity?
• Other uses in wet-weather and watershed planning and management—Can the
data be used by State agencies as support for other CSC) arsJ watershed planning
efforts?
Careful selection, collection, analysis, and presentation of informal! •: rc.jtcJ to measures
of success should allow municipalities, States, and EPA to demonstrate t!u "vrKtii^ and long-
term successes of CSO control efforts. Notwithstanding the effort u> tk\„, <: rational measures
of success, municipalities should identify measures, document baseline ... nJiu-mv and collect
appropriate information that demonstrates the cause and effect of CSO impja- and the benefits
and success of CSO control. It is likely that measures of success \\ ill \an from municipality
to municipality and will be determined by the environmental impacts 01 CSOs on site-specific
basis.
2.9 COORDINATION WITH QUALITY STANDARDS AUTHORITY
A primary objective of the LTCP is to develop and evaluate a range of CSO control
alternatives that will be sufficient to provide for the attainment of WQS, including designated
uses of CSO-impacted receiving waters. To ensure that the LTCP will meet this objective, the
WQS authorities, along with the NPDES permitting authorities, EPA, and the permittee, should
2-12 August 1995
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Chapter 2 Introduction to CSO Permitting
be involved throughout the LTCP development process. This will enable everyone to have an
opportunity to review the proposed type and extent of data and information to be collected
during LTCP development. Such data and information should be used to assess the attainability
of the designated uses and might assist States in more precisely defining the use(s) of the CSO-
impacted waters. For example, the information could be used to refine the existing WQS to
reflect the site-specific wet weather conditions for CSO-impacted receiving waters. The CSO
Control Policy recognizes that the review and appropriate revision of WQS is, in many cases.
an integral part of LTCP development.
The CSO Control Policy discusses several types of WQS revisions in the WQS program
that potentially could be used to address wet weather conditions. These types of revisions
include the following:
* Development of site-specific criteria
• Modification of a designated use to include a partial use reflecting situations where
a certain event (e.g., a storm) precludes the designated use from occurring
• Modification of a designated use to define the use with greater specificity (e.g., warm
water fishery in place of aquatic life use protection)
• Temporary variances from water quality standards.
These mechanisms are described in detail in the Combined Seiver Overflows—Questions
and Answers on Water Quality Standards and the CSO Program (EPA, 1995h). The decision
regarding the mechanism to pursue when considering the WQS revisions will be based on a
variety of factors. Thus, the permittee should consult with the NPDES permitting authority and
State WQS personnel to determine the most appropriate option.
Data needs, monitoring protocols, and models to be used for system characterization and
compliance monitoring should be agreed on early in the process. The water quality impacts of
the existing CSOs can then be evaluated to establish a baseline, which can be used to assess the
effectiveness of CSO controls once they are implemented. These models and protocols can also
2-13 August 1995
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Chapter 2 Introduction to CSO Permitting
be used lo predict whether WQS are likely to be attained after the LTCP has been implemented.
The information and data collected should assist States in assessing the need for revising WQS
and implementation procedures to better reflect site-specific impacts of CSOs. In addition,
coordinating the LTCP development and the review and revision, as appropriate, of WQS and
implementation procedures should ensure that the permittee's LTCP and the requirements
included in the NPDES permit will be sufficient to comply with the water quality-based
requirements of the CWA.
Any review and revision of WQS to reflect wet weather conditions should be conducted
with full participation of stakeholders within the affected watershed. This should include the
sharing of CSO, storm water, and other point and nonpoint source data among stakeholders.
This will enable NPDES permitting authorities and permittees to implement a comprehensive
watershed management approach and allow permittees to coordinate the development and
implementation of their individual LTCPs with one another.
244 August 1995
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CHAPTERS
PHASE I PERMITTING
Consistent with the Combined Sewer Overflow (CSO) Control Policy, the National
Pollutant Discharge Elimination System (NPDES) permitting authority and the individual permit
writer should approach the CSO permitting process as a two-phased process. This chapter
provides guidance on developing and issuing initial or Phase I NPDES permits for CSOs, In
particular, it discusses how to develop permit conditions for implementation of the nine
minimum controls (NMC) and development of the long-term control plan (LTCP) to meet the
technology- and water quality-based requirements of the Clean Water Act (CWA).
3.1 PHASE I PERMIT PROCESS
The Phase I permit should require the permittee to immediately implement the NMC,
document implementation of the NMC, and develop the LTCP. The Phase I permit should also
require the permittee to gather data to establish the baseline conditions against which CSO
controls will be measured.
3.2 INFORMATION NEEDS
In general, the permit writer can draft and issue a Phase I permit with a minimal amount
of CSO information, because he or she can require the implementation and documentation of the
NMC and development of the LTCP without site-specific data in a generic manner, Much of
the data collection should occur during implementation of the NMC and development of the
LTCP, and the Phase I permit will contain requirements to obtain those data. Although the CSO
information base might not be extensive at the outset of the Phase I permitting process, the
information base should grow and evolve during the term of the Phase I permit.
To draft and issue a Phase I permit, the permit writer should have a clear understanding
of the jurisdictional boundaries and responsibilities for the combined sewer system (CSS). This
information is necessary to determine which NPDES permittees should be subject to CSO
requirements. Generally, where the CSS and publicly owned treatment works (POTW) are
3-1 August 1995
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Chapter 3 Phase I Permitting
operated by a single municipality, the permit wiE be issued to that municipality. Frequently,
however, the relationship is more complicated; several municipalities might own part of the CSS
but discharge to a single POTW treatment plant. In this case, CSO permits may be issued to
several different municipalities.
In addition, the permit writer should have a thorough understanding of the permittee's
past and current progress toward controlling CSOs. First, the permit writer should know which,
if any, of the NMC have already been implemented. If any of the NMC have been implemented,
the permit writer may determine that site-specific rather than generic permit language is more
appropriate for continued implementation of those minimum controls. (See Section 4,4.2 for
a discussion of site-specific permit language for the NMC.) The permit writer should also know
whether the permittee has substantially developed a CSO control plan, is implementing a CSO
control program, or has substantially completed construction of CSO control facilities. If the
permittee has completed efforts to control CSOs, the permit writer should consider mis progress
when drafting the Phase I permit, (Section 3.5,3 provides more information on addressing
ongoing CSO control efforts).
The permit writer should also know the approximate population of the community served
by the CSS. If the CSS serves a population of less than 75,TOO. the permit writer may give
special consideration to the permittee in developing the LTCP. (Section 3.5,3 provides more
information on small system considerations.)
In some instances, pertinent CSO information might be difficult to obtain. In any event,
the permit writer should, using readily available information, develop permit conditions requiring
the permittee to implement the NMC, document NMC implementation, and develop the LTCP
as soon as practical.
Information may be obtained from the NPDES permit application or through informal
requests by letter, telephone, or in-person visits. In a limited number of cases, the permit writer
may use a more formal mechanism, such as a CWA Section 308 information request or State
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Chapter 3 Phase I PemtMng
equivalent. The Section 308 information request is likely to be an effective approach to obtain
information because failure to comply with a Section 308 information request may result in an
enforcement action. The permit writer should follow the EPA Regional or State-specific policies
regarding such information requests.
3.3 IDENTIFICATION OF CSO OUTFALLS IN THE PERMIT
The permittee might not have identified the locations of all CSO outfalls prior to the
issuance of the Phase I permit, although this is a desirable goal. To the extent that the CSO
outfalls are known, the permit writer should list them in the permit. If the exact location and
number of all outfalls are not known, however, the permit writer should not wait to issue the
Phase I permit until this information is available but should include generic permit language to
encompass all CSOs. All CSO outfalls should be identified as the municipality characterizes its
CSS during LTCP development. Exhibit 3-1 provides example permit language for a CSS for
which all CSO outfalls are not known prior to issuance of the Phase I permit. The permit writer
should evaluate this language carefully to ensure that it is appropriate for the permittee.
Exhibit 3-1. Example Permit Language for Identifying CSO Outfalls in the
Phase I Permit
He permittee is authorized to discharge,from the CSO outfalts listed below and additional CSO outfalls
within the boundaries of the permittee's jurisdiction identified after the effective date of the permit. The
permittee shall ensure thai all CSOs from the CSS comply with the requirements of [Insert appropriate
permit $eetion(s) containing CSO requirements] and other pertinent portions of this permit.
, -• "Outfall Number • •. •••K-. .Overflow^Outfall Location :\;, Receiving Water Body
- [insert number} " •:-^.^j.:-': [insert latitede/loiigitode ;;i"' :...^;;^ tiasert name of
"• .. '' ' ' '• •• ;f;f|-Ki (street address optional)] : ' ''^'receiving water-body}"
3.4 NINE MINIMUM CONTROLS
The Phase I permit should require all permittees to immediately implement technology-
based requirements (best available technology economically achievable (BAT)/best conventional
pollutant control technology (BCT)) which, in most cases, are expected to be the NMC, as
determined on a best professional judgment (BPJ) basis by the NPDES permitting authority. The
NMC are controls that are designed to reduce the magnitude, frequency, and duration of CSOs
3.3 August 1995
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Ctopter 3 ^ Pirns e I Permitting
and their effects on receiving water quality. Typically, they do not require significant
engineering studies or major construction and can be implemented in a relatively short time
period. Section 301 (b) of the CWA requires immediate compliance with technology-based
controls (i.e., BAT or BCT). Thus, if immediate compliance with the NMC cannot be achieved,
an appropriate enforceable mechanism should accompany the permit. The enforceable
mechanism should contain a compliance schedule for implementing the NMC as soon as
practicable, but no later than January I, 1997. (See Section 3.4.1 for more detail.) Section 2.4
describes additional mechanisms for implementation of NMC in cases where the permit is not
expected to be reissued in the normal five-year cycle prior to January I, 1997.
The NMC are intended to provide technology-based controls, applied on a site-specific
basis, that will immediately reduce CSO impacts on water quality and that can be implemented
early in the control process without the type of in-depth studies necessary for the LTCP.
Exhibit 3-2 lists examples of NMC measures. Section 3.6 further discusses the use of the NMC
to satisfy the BAT/BCT requirement on a BPJ basis. The U.S. Environmental Protection
Agency (EPA)'s Combined Sewer Overflows—Guidance for Mne Minimum Controls provides
a detailed description of each minimum control, example measures for each control, and their
associated advantages and limitations (EPA, 1995b). Although the permittee will be responsible
for implementing technology-based control measures that satisfy each of the NMC, EPA does
not expect that a separate set of control measures will necessarily be required for each control
Rather, EPA encourages a holistic approach to addressing the NMC. For example, the same
control measure(s) could satisfy both "Control of Solid and Floatable Materials" and "Pollution
Prevention."
3.4 August 1995
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Exhibit 3-2. Summary of the Nine Minimum Controls
Minimum Control
Proper Operation
and Maintenance
Maximum Use of
Collection System
for Storage
Review and Modify
Prctrcatment
Requirements
Maximum Flow to
the POTW for
Treatment
Eliminate Dry
Weather Overflows
Examples of Control Measures
Maintain/repair regulators
Maintain/repair tidegates
Remove sediment/debris
Repair pump stations
Develop inspection program
Inspect collection system
Maintain/repair tidegates
Adjust regulators
Remove small system bottlenecks
Prevent surface runoff
Remove flow obstructions
Upgrade/adjust pumping operations
Volume Control
* Diversion storage
* Flow restrictions
• Reduced runoff
« Curbs/dikes
Pollutant Control
• Process modifications
• Storm water treatment
« Improved
housekeeping
• BMP Plan
Analyze flows
Analyze unit processes
Analyze headloss
Evaluate design capacity
Modify internal piping
Use abandoned facilities
Analyze sewer system
Perform routine inspections
Remove illicit connections
Adjust/repair regulators
Repair tidegates
Clean/repair CSS
Eliminate bottlenecks
Minimum Control
Control of Solid
and Floatable
Materials in CSOs
Pollution
Prevention
Public Notification
Monitoring
'' Examples of Control Measures
Screening - Baffles, trash racks, screens (static and
mechanical), netting, catch basin modifications
Skimming - booms, skimmer boats, flow balancing
Source controls - street cleaning, anti-Sitter, public
education, solid waste collection, recycling
Source controls (see above)
Water conservation
Posting (at outfalls, use areas, public places)
TV/newspaper notification
Direct mail notification
Identify all CSO outfalls
Record total number of CSO events and frequency
and duration of CSOs for a representative number
of events
Summarize locations and designated uses of
receiving waters
Summarize water quality data for receiving waters
Summarize CSO impacts/incidents
I
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Chapter 3 Phase 1 Permitting
Implementation of the NMC should enable the permittee to achieve an intermediate level
of CSO control while the LTCP is being developed. Implementation and documentation of the
NMC should involve the following steps:
Evaluate alternative control measures for implementing each of the NMC. The
permittee should be required to evaluate alternatives and select appropriate control
measures to meet the NMC.
Implement the most appropriate control measures. The permittee should be required
to implement those control measures that are most appropriate for the site. The
control measures should be refined in Phase II, as appropriate, to reflect the
information obtained during the Phase I permit term. These control measures should
eventually become part of the long-term CSO control program.
Document implementation of the selected control measures. This documentation
should detail the baseline conditions prior to NMC implementation, the permittee's
evaluation of the efficacy of CSO controls after implementation of the NMC, the
baseline conditions upon which the LTCP should be developed, and the degree to
which the NMC are sufficient to provide attainment of water quality standards
(WQS).
Report on implementation. The permittee should be required to submit appropriate
documentation to illustrate implementation of the NMC (discussed in Section 3,4.2).
3.4.1 Implementation Considerations
Because the compliance date contained in the CWA for technology-based requirements
has lapsed, the permit writer should require the NMC to be implemented immediately. When
the permittee cannot comply with such permit conditions, the permit writer should coordinate
with enforcement authority staff to prepare an enforcement order, including a compliance
schedule with fixed dates. In accordance with the CSO Control Policy, the NMC should be
implemented with appropriate documentation as soon as practicable, but no later than
January L 1997.
Exhibit 3-3 provides example permit language requiring implementation of the NMC.
The permit writer should evaluate this language carefully to ensure that it is appropriate for the
permittee. The permit writer must also prepare a fact sheet or statement of basis associated with
the implementation of the NMC. The permit writer must show that the permittee's NMC satisfy
3-6 " August 1995
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Chapter 3
Phase I Permitting
Exhibit 3-3. Example Permit Language to Require Immediate Implementation of the
Nine Minimum Controls
L ' Effluent I4auts :'"''/' '.•'.• .-
A. Technology-based teipikeineEnte for CSQs. 'The -permittee
recpiremenis: ' '. •,":•' .. • ' • .• V s . '.*•• . <
. ..I. The -permittee- Mall inipfeiiientpraipero^ • . •
GS0 outfalls- to reduce the jnajpihude^.ix'equeacy, and" deratfen.-Of CSOs,. , The. program shall consider- . • . . •
' regular sewer " inspectioBs;: *wer , • caieh. basin, and t egulitor-deaaaig; «pipjnem asd se wer collection •
• systtm.:«pak Qr-repiaee«itt, :where necessary; and. diaofflwciofetiflllegatcoBnections. ; " ' ''"
2. lliue pejtxaidee-sh^jinpleira system for wasiewattr.
. . -.storage -that can- fce-a&coi&mqditted:- by 'the- storage capacttpibf tbe;':coileetioi! system in order to reduce the
magnitude,, feqneney, -and dtestisiwrf CSQs. • V/:::'-vi .----• •
3, 1Tie-;-.per!3ppee shall' review and modify, 'as'.i^ropriatB, iis;-e3dsting..ptetreaHnent prop rim iv minimize CSQ
impttB: ftom te dfec}jatjes--froiii:-B0iKlotisestic esers, ;: : • ;. ^
: ' [AJteraativg iauguage for a jpsermirtee without an approved pretreatmeut program:) Tht permittee -shall
evaluate the CSO impacts: from 'aondomesttc. users aml^take-Jippiopriate steps 10 miRinn.'t suvh impacts. ,^ .
-4. The- 'peooitiee- shall operate t3fe'P0TW treatment plant -at maximum tttaable flew ju-ir.- *!;
- fl(jw--:coHd!tions. to reduce the-raSfnitude, .frequencyi, and.duration:,-:0f'CSOs. the pcrnntus-
• .. •Qogws --to- the treatment plant ••within: the •<»iistraiiitsofte,tteasnjeat^catpacmi ol UK f-nru
5.' Dry- weather overflows -from: CSC) 'outfalls.: ajfc'proMbitefl, 'Each dry weather i«crfi •». n-.- be ftrHjrted to-
- - the.,i»rMtfiag:-.atttbot%;aS-SC»a^-flie:pecnfittee-be«^
detects a- diy weaflser 0verfl6writt».peiBiktee shaft begin ooirtaive action imnK-u
shall 'itt^eiet fi»-«iry -weather.. overfiow :.e.aic.h sufesejpeaf'day «wM-;flie ovcrflfw. h4
-• 6, The penoittee shall -'implement measires to control 'solid and floatable matem;- a c**> *
- 7, The petmittte shall impIeiBent4"|»ltoUion-pre»aMiQn-prograiB'.locused on rcJu, ir tii- >r;tf **t «•! CSOs on
. ^receiving -waters. .' :"- "' '•'''..'.
8. The 'p^Etoinee shall iinplem^ffi.s-puWic'«ottHcation.proc«s;td iafonn citizen*. «•: »u • *-•»• »ttrrr CSOs ^
•occar; -The process' must include- (a) a mechanism to alertpersons of the rtuurrr!* - •: C s >. jinJ (b) a '•- .
''"' ' system to determine- the aature and duration of -.conditions' 'tot are potentialK h*rm*i. t f u^rr^ n( receiving
GSOs. ' . ;- ' ";" - :- - .
weather.
deliver all
ui» permittee
T"hc fcrmmee
;tr:ruicd.
9, Thspsxmjttst ^^mammt-CSQ:Og^i^::W-cliXxtma&O-mp^ctsaRd tiv. ctu.j.t >i- TSft controls'.
"Ms •shall/include collection. of daa fliai 'will be. used to; documettt the existing hjvlin? <•> -nJitions. evalaate-
"the. efficacy: of the -JectooIogy-based.controis.'and-detBnriHJtthe -baseline conJiti<'.oiit&)Is'inttie CSS"' '' -.;••' "''
'b. Total number of CSO evenls-'asid-'fc.-.freqiKncy-'and:di!fadon. of CSOs for a representative number of ''" ^
' --events • ' !1- ' .. •'" -= -5': :f"
c. Lec-arioas aaid designated uses:of-receiving.watet-bodies' •.''•'.:;; . .-$-£
d. Water qualiy data for/receiving:' water -bodies- • •'-.-...>..:• - :^:!ii •
e. 'Water quality- impacts..Jdtrecfly- related to-CSOs (e.g., beach'qloskg,'featables wash-up episodes, fish ';'^;
''kills),' ;, : -:;::'-: :'- '•' . ' . :-'..-';.: - '; ;. ^
3-7
August 1995
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Ctuyter 3 ' ^ Phase 1 PermMng
the BAT/BCT requirements based on BPJ of the permit writer, considering the factors presented
in 40 CFR 125,3(d). These factors include the age of equipment and facilities involved.
engineering aspects of the application of various types of control measures, and the
reasonableness of the relationship between the costs of attaining a reduction in effluent and the
effluent reduction benefits achieved. The Training Manual for NPDES Permit Writers contains
additional details on the use of BPJ in developing permit conditions (EPA, I993g).
When the permittee is already implementing some or all of the NMC, the permit writer
should customize the permit language to address site-specific conditions. For example, if the
permittee is already implementing an operation and maintenance (O&M) program, the permit
writer might craft language that specifically addresses CSS inspection frequency, If the
permittee is already controlling solid and floatable materials, the permit writer may augment the
general language to address the specific controls being implemented. Where the permittee has
already selected long-term CSO controls, the permit writer should coordinate the development
of the permit language requiring NMC implementation with implementation of such controls.
This is because some of the control measures might not be appropriate when the selected long-
term CSO controls have been implemented (e.g., if a CSO outfall is being eliminated). Section
4.4.2 addresses potential site-specific permit conditions in greater detail. Most importantly, the
permit writer should ensure that the permit language reflects the permittee's site-specific
conditions, is consistent with the CSO Control Policy, and is enforceable.
It is important to note some additional implementation considerations pertaining to
specific minimum controls:
Pretreatment: In the case where the permittee does not have an approved pretreatment
program under 40 CFR Part 403, the permit writer should require the permittee to identify its
nondomestic users, evaluate the impacts of such users on CSOs, and take steps, as appropriate,
to minimize these impacts within the CSS "up-pipe" of the CSOs, Alternative language for this
situation is presented in Exhibit 3-3.
3-8 August 1995
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Chapter 3 ^ Phase I Permitting
Maximizing flow: In developing a permit condition for maximizing flow to the POTW
for treatment, the permit writer should consider the secondary treatment regulations in 40 CFR
Part 133, which specify numeric effluent limits for biochemical oxygen demand and total
suspended solids, as well as a minimuin percent removal (85 percent) for secondary treatment.
Secondary treatment requirements are enforceable conditions in POTW permits.
Section 133.103(a) and (e) provides relief for POTWs with CSSs that process elevated
flows (and more dilute influents) by allowing for the possibility of a waiver of the percent
removal requirement. Waivers from effluent concentration limits are not available, however.
The decision to apply a waiver and the recalculation of the percent removal are made on a case-
by-case basis.
i
3.4,2 Documentation and Reporting
The Phase I permit should require the permittee to submit documentation demonstrating
the implementation of each of the NMC. The CSO Control Policy recommends that the NPDES
permitting authority require this documentation to be submitted as soon as practicable but no
later than two years after permit issuance. The purpose of the documentation is to 1) verify that
the permittee has evaluated, selected, and implemented CSO controls for each of the NMC,
2) document the existing baseline conditions, evaluate the efficacy of the CSO controls after
implementation of the NMC, and determine the baseline conditions upon which the LTCP should
be developed, and 3) evaluate the degree to which the NMC are sufficient to provide for the
attainment of WQS.
The permit should require the permittee to document and report the evaluation and
selection of the most appropriate control(s) for each minimum control. Exhibit 3-4 presents
example permit language requiring such documentation. The permit writer should evaluate this
language carefully to ensure that it is appropriate for the permittee. Exhibit 3-5 and EPA's
guidance for nine rflinimum controls (EPA, 1995b) contain examples of NMC documentation.
The permit writer should review the example types of documentation in Exhibit 3-5 and the
NMC guidance document and choose the appropriate items to be required in the permit. NMC
3-9 August 1995
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Chapter 3 Phase I Permitting
Exhibit 3-4. Example Permit Language for Requiring Documentation and Reporting
of the Nine Minimum Controls
II, Reporting Requirements v' ' ..:-•-., •-- ,: , " /• _ :* ^ ^ ^jv..;
A, Reporting implementation^of nine..imnimiiffl .controls." The permittee shall submit documentation that
demonstrates implementation of each of the nine minimum-controls thai; includes the elements below. The
:: permittee shall submit this documentation to the permitting authority oa or before [Insert due date).
;:: :, " [insert appropriate list of documentation items] """ :
documentation may come in a variety of forms. For example, the permittee may submit reports
and studies prepared for other purposes, such as operating or facility plans, revised sewer use
ordinances, sewer system inspection reports, technical studies, and pollution prevention program
plans; public notification plans; and contracts and schedules for minor construction programs for
improving the existing system's operation.
The documentation required in the permit should be the mimmutr am vjm necessary to
demonstrate that appropriate NMC measures are being implemented tr .iJJm,*n. ihe NPDES
permitting authority may choose to require the municipality to keep s.«nu- ri\>»rJs of NMC
implementation on site rather than requiring all documentation to he sutnr.nc-J In these cases,
NPDES inspectors can review documentation that is on file during m^pv»;i -n-
Although not reflected in the example permit language in Exhibit *-4. the permit writer
may require periodic reports on the implementation of me NMC through. HI; the lerm of the
permit. For example, the permit writer may require updates on am Mcmd-ant chances in NMC
implementation. In addition, the permit writer may require the submission of monitoring data
at a specified frequency throughout the term of the Phase I permit. In am case, the permit
language should reflect the permittee's site-specific conditions.
3.5 LONG-TERM CONTROL PLAN
The second major element of the Phase 1 permit is the requirement to develop an LTCP
that will ultimately result in the permittee's compliance with CWA requirements. For this
reason, the LTCP should contain CSO controls that are adequate to provide for the attainment
3-10 August 1995
-------
Chapter 3 J
Exhibit 3-5. Example Types of NMC Documentation
Proper opsrattes and' regular mantteaanc* programs- 1l •'' . . "'" ;%. . ' •
An jroentory of CSS components requiring: routine operation and maintenance .. '• ' •
An evaluation of opeiatiouxand maintenance procedures :te include regular inspections; sewer, eaiefs basin, .and •
- regulator cleaning; •and equipment, and-«wer polleetioa system repair or replacement .where necessary ••. ,;;:;:;:
Copy of, -or excerpts- from, -an operatioa-'and -maintenance manual and/or procedures lor .the-CSS- and CJSO ."-
-, stfuctares ?!- • ;':-- - . ' " ...... - $t^-& v • ''' * ...,•••.-'::•'•
Resources allocated. (masqKJwer^. -equipment, trainiflg)"for"BjafaienaKe-of the CSS and CSO-stracaffes ,,... -
A 'summary- of. iitspecDixascon^ s ,. $ \ lr,.;._. ' ""; '
of us® of the- sewer collection system for storage
An -analysis/study of alternatives to maximize collection system storage ,;•• '>'. '" ' . :.. •
A 'descnqptibn-df procedures in place' -for -xoanondng cpiiectjon system storage '•'• , '"' ', - .. •"•'
AJQ impleioeiiatioo 'schedule --of mioor-eonsaucnba associated with maximbdng collectioB system storage . :
Deseriprion.of-actions taken to .nuotunize. storage • ''.•'•'. I •; ;• t-, " • '•'"'• ~
Identifiettiottof odsting-off-lme storage potential- .. :s . -••- >
Ideatifcation- of %sy: additioual potential actions w- increase' storage in the existing coltectiou ^ittia^ but-tbat •'• :
require further-' analysis; do«mefltatiofl.-thai they 'will be/were evaluated in hydraulic- studies conducted as part
oftheLTCP' ' . .::-:'. ":'-;"' - i: ••-:-•• ^^ ' ^ .._. ^ ,;.-:,:- -.
Re?riew:aad'iiiodffi£stioBi;-'0f .controls' on 'nondomesfic- sources ,i::;;: , ', '....-:-
. . ...
of an inventory of nondomestic discharges aoad-aswssment of the impact of such discharges .on -CSOs-
Analysis of -feasibility of modifications to nondomesdc source. controls (including local pretreaimeni program, if
'appropriate} to reduce the impact of sucft- discharges on-.CSOs '3V.. , ' l --:
of selected modifications :-. • ' ..,. s \ %!?; •&. '. ' ,,. ''".
M«lni4rati«ffl, of flow .to-tbe'FOnrW-'treatnwDt plan* for. teeatment ,"" .^,-, ;i
:-:-, • .'' ' <;• •' ; ' ^''-
Results of 'any study/analysis' ftf existing condidom and a comparison with the design capacity of 'the
facility v, ' ' - "'" * ••- -jif' '"•- : """''"
Results or status of any engineering studies to increase treatment of -wet weather flows '>'''•
Documentation, of actions taken to maxlouze flow 'and the-ntagnitade of increase obtained or projeettd ' :
Einsfaatt&H -®f CSOs dsMriiig:dry weather flsw.eeiiditioiB _,,;;: <-. ^ . . ,--:: ••-
A summary of dry weitheir overflows that occurred, Inclading -location, dwration. and frequency' . =
A -de^ription of procedates- for.. notifying pennitdng; authority of dry weather overflows . s;-f .;• '• "::
A summary of actions taien to identify dry weather oyerfiows--and progress toward eliminating -dry weather p-
overflows '"' '"' - . '"' -.- . '"' ' -- :':- K;: ; !»},
A plan- for eomplete- eluninatton .of afl dry weaiher overflows. s.; :-: ?:'. -1 'f'; -: ••'• -•••'
ConttMil of solid and Itoaiable materials- in. CSOs ( „,, " ..... '"" $''f. * i9 '--' ;:
An engmeeiing' evaluation -of procedures or technologies censideted for controlling sold «nd -ftoaiable - materials
A description of CSO controls in place for solid 'and floatable materials •' j' w.Xs; . ; • H;-;- -
A- schedule for minor constractipB . x '<*••' • „%&$• *'''• f^S " ^ly-^. • " --
DocamentaMon of -any -additional controls to be inswUed or: implemented :'"':'5'' :' ' ''*,
3-11 August 1995
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Clwpter 3
Phase I Permitting
Exhibit 3-5, Example Types of NMC Documentation (Continued)
Pofiuiien preveetton
to^
An evaluation of pollution prevention opportunities to include procedures to coBire! solid arid floatable
materials ~ ..'",' . . _ ; =
A description of selected pollution preveatioa ojspommlti.es to include resources allocated
f^blfe notification • '-" • ; '• ; " : • .- '", • ::-'
An evalaatioa of public nctifieafioa options,: incfadifig descriptioa of existing and/or proposed' public
aotificaiicia procedures '• • _ ; •• /, • "' •
A *teserijKl0n: of. Elected paMe tmtificatioii mefiiods ..:...-,'.' • - • ' •' '•''••
A k>g of CSO . "' . '- '
_
A summary of reeei^iag water impacts droxtly relaled to CSOs (e.g., beadi dosing, fioatebles
' " "'"
.
• An assessniect of the effectivei^ss of any CSO control mEasuies ;alread>' itaplemented (e.g., reduakia of
floatable®)- " •• . . • , ' ... / . .-• •
' a nwmsoiiag plaa fcsr th<CP, w an>ropriate ' ; , :.
of WQS—that is, they will ensure tiaat designatel uses are not impaired and the State's water
quality criteria are not exceeded. The CSO Control Policy recommends that the permittee
develop and submit the LTCP as soon as practicable but generally within two years after the
requirement to develop the LTCP is incorporated into a permit, Section 308 information request,
or enforcement action. The CSO Control Policy also recognizes that it may be appropriate for
the permit writer to establish a longer schedule for completion of the LTCP based on site-
specific factors.
The LTCP development process is a comprehensive planning effort designed to evaluate
a range of CSO control alternatives and result in the selection of CSO controls that will provide
for the attainment of WQS. For this reason, the LTCP development process will be an
incremental and, frequently, a sequential process. For example, a permittee should assess the
impacts of CSOs on water quality prior to identifying a range of feasible CSO control
3-12
August 1995
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Chapter 3 Phase I Permitting
alternatives. In establishing the requirements to develop an LTCP, the permit writer should
consider the site-specific conditions of the permittee. In a limited number of cases,
implementation of the NMC may be sufficient to provide for the attainment of WQS and the
permittee's efforts to develop an LTCP should appropriately reflect this situation. In other
cases, the permittee may have already begun the CSO planning process and the requirement to
develop an LTCP should be tailored to reflect ongoing efforts.
TMs section provides guidance for the permit writer on how to require development of
the LTCP in accordance with the CSO Control Policy. Section 3.5.1 describes each element of
the LTCP, Section 3.5.2 presents the schedule for development of the LTCP, and Section 3.5.3
discusses considerations for small systems and ongoing CSO control efforts. EPA's Combined
Sewer Overflows—Guidance for Long-Term Control Plan contains technical guidance on the
development of LTCPs (EPA, 1995a).
3.5.1 Components of the Long-Term Control Plan
The CSO Control Policy outlines the following minimum LTCP components:
* Characterization, monitoring, and modeling of the CSS and receiving waters
(including identification of sensitive areas)
* Public participation
* Consideration of sensitive areas
• Evaluation and selection of alternatives
* Cost/performance considerations
* Operational plan
* Maximization of treatment at the POTW treatment plant
» Implementation schedule
• Post-construction compliance monitoring program.
3-13 August 1995
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Chapter 3 Phase I Permitting
In general, the permit should guide the development of the LTCP consistent with the
CSO Control Policy, establishing distinct Incremental actions, providing the permittee with
flexibility in conducting the planning process, and ensuring enforceability of subsequent Phase
II permit conditions.
Exhibit 3-6 provides example permit language requiring the development of an LTCP,
This exMbit was intended to provide practical, realistic example language which should not
necessarily be considered as boilerplate language. Thus, the permit writer should evaluate this
language carefully to ensure that it is appropriate for the permittee. The permit conditions in
this exhibit include all the components of an LTCP outlined in the CSO Control Policy. The
permit writer should list specific LTCP components in the permit rather than simply require the
permittee to develop an LTCP consistent with the CSO Control Policy. A permit condition such
as, "The permittee shall complete and submit to the permitting authority an LTCP by [date
specified]..." may result in the submittal of an incomplete or poorly developed plan. Listing
the individual components of the plan requires the permittee to consider all of the necessary
LTCP components.
The public participation component of the LTCP is discussed first in this section because
it is important for the permittee to identify potential stakeholders and formulate a process that
will facilitate their active involvement in LTCP development. This should be done as early as
possible in the LTCP development process.
3.5.1.1 Public Participation
Under the CSO Control Policy, the permittee should employ a public participation
process that actively involves the affected public in the decision-making to select the long-term
CSO control(s). According to the CSO Control Policy, the affected public includes rate payers,
industrial users of the sewer system, persons who live adjacent to or use water bodies affected
by CSOs, and any other interested persons. Public participation is critical to the ultimate success
of the CSO controls selected by the permittee, given the potential financial impact (e.g.,
increased fees) to the affected public. Early and constant public participation during the
3-14 August 1995
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Chapter 3
Phase I PermMng
Exhibit 3-6. Example Permit Language for
Requiring the Development of a Long-Term Control Plan
III. Long-Term Control Plan ';. . "', «:->•! • , ,,'"''
Tie permittee shall develop a long-term control plm thai will include the elements- contained in Sections fH.A
through 111,0 below and shall-. submit the plan elements In accordance with, the schedule contained •& Section
IILE:;-, ^.,o: ( ., ^ • ' •' J s* * . * ^ ^ ^ v. •••
A, Public Participation •'• ;, " "" . ., '" .^ ,,.. ••" : .= -:;;¥;??; ^ x
.The permittee shall prepare- and implement a public parttdpatJon. plan -'that outlines- "how the -permittee will
ensure participation of .the public tturougiiout the', long-term. control 'plan- development process;. • • . •
B. CSS Characterization . . t"H":: 'A.;, % ,. . ^J^ '.. '.. H . . .
The permittee shall develop- and .implement a plan that will -result 'in a c»mprefaensive characterization of
the CSS developed through -.records - review, monitoring, modeling, and-- other means as' appropriate to
establish' the existing baseline conditions, evaluate the efficacy of the CSO technology-based controls^ and
x determine the ' baseline conditions upon which : -the- long-term 'opnttpl • plain wUl be based.' The
, characterization shall adequately address the response/of the' CSS to various precipitation events; identify
;£:' die-number, ItKaiion, .-frequency, .and dtaracleristlcs 'of CSOs;- and'Meatify water- qaaMty.. impacts- -that result
:,):. ficom'CSOs, . :S:,A _ ' X4p'ii"- r - - - .* ;;
To complete .the chaiacterizatioQ., -the penaittee. -shall enip-loy the following methods; liyi. :
1. Ra^al|JRe<»ras Review..- - 'The permittee shall examine the-complete.;rajnfell iwoids for .tte- geographic
,'; of tise GSS and evaluate the flow Variations, in the-recetving water' body-: to -correlate "'between the
"' •' CSOs and receiving, water conditions, "; .*. ''•''_,, :.
2, .CSS Records.- Review. Tie permittee -shall review -and evaluate all -available CSS records and undertake
.. .. -'field -'inspections, and other -necessary activities -.to Identify 'the nsmbet, location,; and frequency Of CSOs
-.;• - and their location relative to sensitive -areas, (as identified 'i&..UI;B14).'and to pollution, sources, such-.-as
significant indnstrial users, in -the. collection system.- ' :. ; ---.- • '-.j-' K
3 . ' 'CSP^jnd^WjMerQ^ityJ^pjyitpjEfe^. Tie-permittee shall develop .and submit a monitoriag -program tot
' measures the frequency, duration, flow rate, volume, and pollutant -concentration .'of CSOs and
" • -the impact of the CSOs on .receiving waters. -Monitoring shall be .performed -at. a"' representative number
o-f CSOs for a representative number of events.- The "monitoruig ' program shall -include 'CSOs and
. ambient receiving .water -body monitoring and,- where appropriate-, 'other -monitoring protocols, such as
biological assessments, loxicity testing, and sediment. sampling. ,,'R " '•"-'•
4, Identification of i: Sensitive; Areas. -The permittee -shall identify -sensitive areas to which its CSOs: -occur.
These' areas shall taclwte Outstanding National -Resource Waters, •• National -Manne Sanctuaries, waters
with threatened orendangered species and 'their designated' critical.- habitat, waters with primary, contact
. recreation, public drinking water intakes or their designated, protection, areas, shellfish-" beds* and any
j other areas. identified" by -the. permittee or permitting authority, in -coordination with appropriate -Sate or
.4;- Federal agencies. ,-.?:< . -;; ...... .:.; •
5, CSS ...aftd..Receiying WatCT,ModeUn.g. The permittee -may employ models,, which include appropriate
calibration aad. verification with field measurements, to aid in the diaracterizatioii. . If models are used.
:f they shall be identified by the pennittee -along w.ifh an explanation of why- the model' was selected and
"• used in the characterization. ... '-P •„ .. . „.-'-. .;- r' • • .
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August 1995
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Chapter 3 Phase I Permitting
Exhibit 3-6. Example Permit Language for
Requiring the Development of a Long-Terra Control Plan (continued)
C. CSO Control Alternatives. ' , „.,.. -;v - >s *.."'•'•'. 1 ., _ . . I
L Development of _CSQ Control Alternatives, - '•• The permittee- shall -develop a range of CSO -control j
-alternatives that would- bt necessary to achieve- [insert appropriate range: of levels of cojittol ,. 'JpSf;.; : .. • ?«
D. Selected CSO Controls' p' _,,/;£ - ' ;'v -- . • . f:!l.j|:: lk£^ • •'
Once the 'permittee has selected -the CSO controls to:-consultation with the pemutriag authority, the
. permittee .shall submit-the foEowIng: *- ; -, ' - :-:"--,. :; .; .,
:- L. Implemeaiariofl .Schedule.- The permittee shall submit a construction, schedule for the selected;CSO
- 'controls as part of-the implementation schedule. ' Such schedules m&y be phased based oa- the -relative
M ' impoftance-of the adverse impacts on water quality standards and on the penalrtee's' -'financial capability.'
,j 2. Operational 'Plan. .The permittee, shall submit a revised- operation' Kid maintenance plan that addresses
;||f;'|:,-; implementation of the selected-CSO controls. 'The revised operation .and maintenance plan shall
•;- '•'''- maximize the removal of pollutants daring and after -each precipitation event "using all available "facilities
within the collection aad treatment system. H^ n= - ••- o::|j||s;;.; • . '.''..
3. Post-Coiistructiori Compliance Monitoring Proggtm. 'The permittee -shall develop, and -submit -a post-
construction monitoring program- that- (a) is adte|uate to ascertain the-, effectiveness of die CSO.controls
.." \,;s>- and (b) can be used' to verify attainment of water quality standards."' The program.- shall-.include-'a plan
*;^'"': that details, the monitoring protocols to be followed, -including CSO and ambient monitoring and, where
. appropriate, other monitoring protocols, such as-biological assessments, whole effluent toxieify testing,
-J--W, • and sediment .sampling. - ; -1& -.-»v - • "r- -;-:. 4v;.>:.-.,-;;- . ' .%-.
* **' ; _:,.>[_7"- •"•" •'.--• '.; • - •-- .•>:<• >;,, ' T -,\-,
E. „ Schedule and Interim Deliverables fc ""'"' •• '*'""' K ' .. ''" '.: . ;::*s-
' The following reports shall be developed in accordance with the requirements specified in 'Sections III. A
'through IILD and sabmitted to the'permitting authority' by the dates specified below:^ _ ;;
1. PublK^aj^gajloj..^!^. as required in Section ID.A, shall- be submitted on or before [Insert due
r dtate]. ••--•'*' - > .:;i ... ;:: ,.x ... - % >^ ,_. •' •-..
'" 2, CSS..ChgjrgcKmaiiop Moniioriag and Modeling plan^ as required in'Sectioa III.B, shall 'be submitted on.
" or before pHsert.dee .date]. .. ••' -. -,- , • *«
August 1995
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Chapter 3 I Permitting
Exhibit 3-6. Example Permit Language for
Requiring the Development of a Long-Term Control Han (continued)
3. CSS.Characlgrimion. Mopi|gmg:..and..Modeling Results. iocludiri|>identificauan of'sensitive areas, -as
required in Section III'.B, shall be submitted on or .before [insert'duedate}.. •• • ' • '
4. •'C^CopUBJ^tenpgvgs.Idfliaific^gn.-'as required ia. Section lli.C.l, staff be s!ibmiwed.:.
-------
Chapters Phase I Permittimg
not necessarily be required. Acceptable documentation may also include summaries of public
comments received.
3.5.1.2 Characterization, Monitoring, and Modeling of the CSS and Receiving Waters
Characterization, monitoring, and modeling activities provide the basis for the permittee
to choose and design effective CSO controls. According to the CSO Control Policy, the major
elements include;
• Examination of rainfall records
• Characterization of the CSS
* Monitoring of CSOs and receiving water quality
* Modeling of the CSS and the receiving water.
As discussed in Section 3.7, initial characterization and monitoring activities are
conducted under one of the NMC (monitor to effectively characterize CSO impacts and efficacy
of CSO controls). If the permittee has already characterized its CSS, CSOs, and impacts OD
receiving waters, permit requirements for further characterization may not be necessary'
(although long-term compliance monitoring will still be necessary, as discussed in
Section 3.5,1.9). If the permittee has not sufficiently characterized the system, the permit writer
should determine whether further efforts are needed and establish permit conditions that specify
the characterization activities necessary to adequately complete this component of the LTCP.
EPA's Combined Sewer Overflows—Guidance for Monitoring and Modeling (EPA, 1995d) and
Combined Sewer Overflows—Guidance for Long-Term Control Plan (EPA, 1995a) present
technical guidance related to proper CSS characterization.
EPA recommends that the permit writer require the permittee to develop a
characterization and monitoring plan that includes the monitoring protocols, procedures, and
associated time periods for collection of data that will be used to characterize the CSS and
receiving waters. (Section 3.5.2 discusses submittal of the plan and other interim deliverables.)
This characterization and monitoring plan should be reviewed by the NPDES permitting
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Phase I Pemuttimg
authority, Slate WQS authority, and EPA Region, As part of this review, these parties should
agree on the data, information, and analyses needed to support the development of the LTCP
aad the review and revisions to WQS and implementation procedures to reflect site-specific wet
weather conditions, if appropriate. In addition, the permittee's proposed characterization and
monitoring plan should be coordinated with other monitoring efforts within the same watershed.
Review and concurrence by these participants should ensure that the permittee collects adequate
but not unnecessary characterization and monitoring data.
3.5,1.3 Consideration of Sensitive Areas
Sensitive areas should be identified as part of the CSS characterization as soon as the
locations of all CSO outfalls are known. The CSO Control Policy indicates that sensitive areas
should be given priority during LTCP development (see discussion in next section). Examples
of sensitive areas are provided in the CSO Control Policy and listed in Exhibit 3-7.
3-7. in the CSO Control
'Resource Waters • ift' ;'
» National "" '• ,. • ...
* Waters with.threatened, or endangered
*' fteers with primly contact-recreation,(e.g., swimming)
• «: • ,.,j. 'S;>|S-r:.j,: " ;?-
* -Public drinking water :ii% """'* • a|F "•
» * ' - ;?,,s ': it -,• .. •"'
The initial identification of sensitive areas should be made by the permittee in
consultation with the NPDES permitting authority and may require coordination with local,
State, and Federal agencies involved in the protection of such areas. For example, the permittee
and permit writer should:
Coordinate with the U.S. Fish and Wildlife Service to determine whether CSOs occur
in waters with threatened or endangered species.
Coordinate with the local public water utility to ensure the designation of drinking
water sources as sensitive areas.
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Chapt&T 3 Phase I Permitting
* Evaluate the designated uses of each CSO receiving water because the State might
have a designated use that corresponds to a sensitive area as defined by the CSO
Control Policy.
The NPDES permitting authority will make the final determination of sensitive areas.
Once sensitive areas have been identified, the permit should require the permittee to give
the highest priority to controlling overflows to these areas. Permit conditions should require the
LTCP to 1) prohibit new or significantly increased overflows to sensitive areas, 2) eliminate or
relocate overflows that discharge to sensitive areas wherever physically possible and
economically achievable (except where elimination or relocation would provide less
environmental protection than additional treatment), or 3) where elimination or relocation is not
physically possible and economically achievable, or would provide less environmental protection
than additional treatment, provide the level of treatment for remaining overflows deemed
necessary to meet WQS for full protection of existing and designated uses.
Section ULC. 1 of Exhibit 3-6 contains example permit language requiring the permittee
to consider sensitive areas during LTCP development.
3.5.1.4 Evaluation of Control Alternatives
The primary objective of the LTCP is to evaluate CSO control alternatives that will
enable the permittee, in consultation with the NPDES permitting authority, the WQS authority,
and the public, to select CSO controls that will meet CWA requirements. To ensure that the
most cost-effective and protective CSO controls are selected, the permit writer should require
the permittee to consider a reasonable range of CSO control alternatives. The CSO Control
Policy encourages the permittee to evaluate CSO control alternatives that provide varying levels
of control such as those that would achieve:
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Chapter 3 Pha$e I Permitting
* Example 1
- Zero overflow events per year (i.e., total elimination of CSOs via storage and/or
sewer separation)
- An average of 1 to 3 overflow events per year
- An average of 4 to 7 overflow events per year
An average of 8 to 12 overflow events per year,
* Example 2
Controls that achieve 100-percent capture for treatment
- Controls that achieve 90-percent capture for treatment
Controls that achieve 85-percent capture for treatment
- Controls that achieve 80-percent capture for treatment
- Controls that achieve 75-percent capture for treatment.
The permittee should develop an appropriate range of control alternatives based on site-specific
conditions.
The CSO control alternatives could include total sewer separation or retention of all
combined sewer flows for subsequent treatment during dry weather. The CSO control
alternatives also could include a combination of controls for an entire system (e.g., partial sewer
separation and retention). In addition, the permittee should consider, among its CSO control
alternatives, expanding POTW treatment plant secondary and primary capacity and associated
appurtenances to enable additional treatment of combined sewage. Thus, the Phase 1 permit
should require the permittee to evaluate the maximization of treatment at the POTW treatment
plant among its CSO control alternatives. EPA's guidance on LTCPs contains additional
technical guidance on evaluating CSO control alternatives (EPA, 1995a).
The evaluation of alternatives will ultimately enable the permittee to select CSO controls,
in consultation with the NPDES permitting authority, WQS authority, and the public, that, when
implemented, will comply with water quality-based requirements of the CWA either through the
"presumption approach" or the "demonstration approach," It is unlikely that a permittee or a
permit writer will be able to determine the level of control necessary to meet WQS requirements
prior to the initiation of the LTCP planning process. Similarly, a permittee will probably not
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Chapter 3 Phase I PetmMmg
be able to specifically adopt either the presumption or demonstration approach until after the
initial planning process has begun and more is known about its CSS and CSOs. These two
approaches (contained in the CSO Control Policy) are described in the following discussion,
Presumption Approach
The presumption approach presumes that the CSO controls necessary to meet the
performance criteria presented in the CSO Control Policy will be sufficient to meet the water
quality-based requirements of the CWA, The permittee may consider the presumption approach
where the level of control needed to protect WQS is unknown, but the permit writer and
permittee agree the approach is reasonable based on the data and analysis conducted as part of
the characterization. This approach is based on the permittee meeting one ot the following
criteria presented hi the CSO Control Policy:
* No more than an average of four overflow events per year. pr«»x i JcJ th.it the NPDES
permitting authority may allow up to two additional overflow event* per vear. Thus,
the permit writer may allow four, five, or six overflow event- per vear. For the
' purpose of this criterion, the CSO Control Policy defines an overt,.-* event as "one
or more overflows from a CSS as the result of a precipitant, event thai does not
receive the minimum treatment specified below."
* The elimination or capture for treatment (as treatment is spcxiheJ tx.-l.-w t of no less
than 85 percent by volume of the combined sewage colkvieJ in the CSS during
precipitation events on a system-wide annual average basis 1 1 > Jeterm me the volume
of combined sewage that must be captured or eliminated, the permittee should
calculate the total volume entering the combined sewer during precipitation events on
a system- wide annual average basis.
* The elimination or reduction of no less than the mass of pollutants identified as
causing WQS exceedances through the sewer system characterization, monitoring,
and modeling effort for the volume(s) that would be eliminated or captured for
treatment, as described under the previous bullet. Again, the permittee, in
consultation with the permit writer, should determine the appropriate volume of
combined sewage to be treated. In addition, the permittee, in consultation with the
permit writer, should identify the specific pollutants and their masses to be eliminated
or reduced.
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Chapter 3 Phase 1 PermMng
For purposes of the first two criteria above, all combined sewer flows in the CSS
remaining after implementation of the NMC should be required to receive the following
minimum treatment:
* Primary clarification (or equivalent) for the removal of floatables and settleable solids
• Solids and floatables disposal
* Disinfection of effluent, if necessary, to meet WQS and protect human health,
including removal of harmful disinfection chemical residuals, where necessary to
meet WQS.
For example, if the permittee chooses to capture 85 percent by volume of the combined
sewage collected on a system-wide annual basis during precipitation events, these flows should
receive the treatment listed previously. The remaining 15 percent by volume should receive
treatment to the greatest extent practicable, and this should be addressed in the operational plan.
For example, in considering what type of treatment constitutes "to the greatest extent
practicable," the permittee may evaluate whether attaching nets as end-of-pipe controls for solid
and floatable materials in the remaining 15 percent is achievable within technical and financial
constraints.
As stated in the CSO Control Policy, the controls selected under the presumption
approach are only "presumed" to meet the water quality-based requirements of the CWA
".. .provided the permitting authority determines that such presumption is reasonable in light of
the data and analysis conducted in the characterization, monitoring and modeling of the system
and the consideration of sensitive areas...." Therefore, the selected CSO control program should
be designed to allow for cost-effective expansion or cost-effective retrofitting if additional
controls are subsequently determined to be necessary to meet WQS.
Demonstration Approach
As an alternative to the presumption approach, the permittee may choose to demonstrate
that the selected CSO controls, when implemented, will be adequate to comply with the water
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Chapter 3 Phase I Permitting
quality-based CWA requirements. An adequate demonstration should include each of the
following:
* The planned control program is adequate to provide for attainment of WQS unless
WQS cannot be attained as a result of natural background conditions or pollution
sources other than CSOs,
* The CSOs remaining after implementation of the planned control program will not
preclude the attainment of WQS. If WQS are not met in part because of natural
background conditions or pollution sources other than CSOs, a total maximum daily
load (TMDL), including a wasteload allocation for point sources, a load allocation
for nonpoint sources, and a margin of safety, should be used to apportion pollutant
" loads to all source discharges.
* The planned control program will provide the maximum pollution reduction benefits
reasonably attainable including the cost/performance considerations below.
* The planned control program is designed to allow cost-effective expansion or cost-
effective retrofitting if additional controls are subsequently determined to be
necessary to meet WQS.
it is important to note some additional considerations pertaining to use of the
demonstration approach:
Naiural Background Conditions: The decision as to whether natural background
conditions preclude attainment of WQS is made during the WQS-setting process by the WQS
authority. "Natural background conditions" of a receiving water body include both naturally
occurring pollutant concentrations and channel and instreain characteristics (e.g., mean stream
width and depth, total volume, flow and water velocity, reaeration rates, seasonal changes,
turbidity, suspended solids, temperature, sedimentation, and channel stability, obstructions, or
changes).
Decisions regarding pollutant sources other than CSOs, on the other hand, are made
during the development of wasteload allocations during the TMDL process. Other "pollution
sources" to a receiving water body could include additional municipal or industrial point source
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Chapter 3 Ftoe / Permitting
dischargers, including facilities or operations with storm water discharges, and nonpoint sources,
such as agricultural and roadway runoff or drainage from abandoned mines.
TMDL: A TMDL is a technically sound and legally defensible tool used by a State to
calculate and apportion to identified sources the allowable amounts of pollutants that may be
discharged into the water body without exceeding numeric criteria or another quantifiable
endpoint (e.g., temperature, riparian habitat). The use of a TMDL to apportion pollutant loads
is illustrated by the following example:
A river segment at the lower end of a watershed is not meeting its designated use because
of excessive concentration of one particular metal. Studies determined that sources of the
metal include a metal finishing plant (300 kg/yr), a PQTW (200 kg/yr), drainage from
an abandoned mine (400 kg/yr), CSOs (500 kg/yr), and atmospheric deposition (5 kg/yr),
The metal finishing plant is meeting its technology-based permit limits and little reduction
in metal loadings can be anticipated without expensive upgrades. No further reductions
in loadings can be achieved by the POTW without expensive upgrades. The mine
drainage can be treated using BMPs to remove 75 percent of the metal (leaving 100
kg/yr). Design changes to the CSS will reduce the metal loadings to 50 kg/yr.
Modeling analyses would then be conducted, and a margin of safety would be identified
to accommodate potential ne\v development or lack of certainty in the modeling analysis.
If this modeling indicates that the resulting WQSfor the particular metal can be achieved
through implementation of those allocations (including the margin of safety), the analysis
constitutes a TMDL. The TMDL should then be submitted to EPA for review under CWA
Section 303 (d).
To help ensure that the demonstration by the permittee will be adequate, the permit writer
should consider defining how the above criteria for "adequate demonstration" will be met. If
the NPDES permitting authority has particular policies or procedures for evaluating water quality
impacts, then the permit writer should place these requirements in the permit.
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Chapter 3 Phase I Permittimg
If natural background conditions or pollution sources other than CSOs are contributing
to exceedances of WQS, then the permit writer should coordinate with the appropriate State
authorities to determine whether a TMDL has been developed or is in the process of being
developed for the watershed in which the permittee is located. Effluent limitations for the CSO
outfall must be consistent with any WLA for that CSO prepared by the State and approved by
EPA pursuant to 40 CFR 130,7. (See 40 CFR 122.44(d)(!)(vii)(B).) The permittee should
demonstrate compliance with such WLA. In the absence of a TMDL for a pollutant or
pollutants, the permit writer should coordinate with appropriate State water quality personnel to
determine how a permittee will demonstrate compliance with WQS in light of the other source
of pollutants.
Under the demonstration approach, the permit writer also should specify clearly what will
constitute a reasonable effort by the permittee to demonstrate the maximum pollution reduction
benefits reasonably attainable. Maximum pollution reduction that is "reasonably attainable" is
the reduction that can be realized through the implementation of CSO controls determined to be
feasible for the individual permittee, recognizing factors such as the nature of the individual
CSS, the characteristics of the receiving water body, and other factors specific to the CSO and
receiving water body.
To provide an adequate demonstration, the permittee should rely upon data collected both
during monitoring done as part of NMC implementation and the characterization, monitoring,
and modeling completed during the initial stages of LTCP development. Using these data, the
permittee should establish that its selected CSO controls will satisfy each of the demonstration
criteria.
3.5.1,5 Cost/Performance Considerations
The permit writer should require the permittee to develop and submit with the LTCP
appropriate cost/performance curves for each of the CSO control alternatives being evaluated.
The permittee develops the curves to demonstrate the relationship between the anticipated
effectiveness of CSO control alternatives being considered and the cost of each. Consistent with
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Chapter 3 Phase I Permitting
the CSO Control Policy, the permittee should be required to include an analysis discussing the
point at which the increment of pollution reduction achieved in the receiving water diminishes
compared to increased costs (i.e., a "knee of the curve" analysis). The permit writer may also
want to require the permittee to evaluate the environmental benefits associated with the cost/
performance curves (e.g., the reduction in the number of days per year that the receiving water
exceeds State bacteriological WQS). These analyses will ultimately help guide the selection of
CSO controls by the permittee, NPDES permitting authority, WQS authority, and the public.
EPA's guidance on LTCPs contains detailed information related to the development and review
of cost/performance curves (EPA, 1995a).
3.5.1.6 Operational Plan
The Phase I permit should generally include a requirement that, once the appropriate
CSO controls are selected, the permittee will revise the O&M plan developed as part of the
NMC to include the selected CSO controls. The operational plan, as it incorporates the O&M
program implemented as part of the NMC, will reduce the magnitude, frequency, and duration
of CSOs. As described hi the CSO Control Policy, the operational plan should be designed to
maximize the removal of pollutants during and after each precipitation event using all available
facilities within the collection and treatment system. The operational plan should also specify
methods to ensure that any flows in excess of the volumes prescribed under the presumption
approach (e.g., flows in excess of 85 percent by volume of the combined sewage collected in
the CSS during precipitation events on a system-wide annual average basis) receive treatment
to the greatest extent practicable. EPA's guidance on LTCPs presents additional information
on technical considerations in revising an O&M program (EPA, 1995a).
3.5.1.7 Maximization of Treatment at the POTW Treatment Plant
As discussed in Section 3.5.1.4 (Evaluation of Control Alternatives), the permittee should
evaluate the maximization of treatment at the POTW treatment plant as part of the LTCP.
As a component of the LTCP, maximization of treatment at the treatment plant is envisioned to
include the use of existing primary excess wet weather flow capacity rather than the construction
of additional treatment capacity. However, as part of evaluating whether the use of existing
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Chapter 3 Phase I Permitting
primary capacity is an appropriate long-term alternative, the permittee should evaluate the
feasibility of expanding either primary treatment capacity or both primary and secondary
treatment capacities.
This component of the LTCP is distinguished from maamkation of flow to' the P0TW
for treatment, one of the NMC, The minimum control focuses on maximizing flow through
the treatment plant so that the combined sewage flow can receive secondary treatment. Thus,
this minimum control takes advantage of existing secondary treatment capacity,
As stated in the CSO Control Policy, maximization of treatment has two benefits:
* Treatment of increased flows during wet weather may enable the permittee to
minimize overflows to sensitive areas
* Combined sewer flows would receive at least primary treatment.
In addition, use of existing primary treatment capacity at the treatment plant may prove to be
a cost-effective alternative based on the cost/performance analyses of CSO control alternatives.
If a permittee determines during its LTCP development that utilization of excess primary
treatment capacity is a feasible long-term CSO control, the permit writer will need to consider
authorization of a CSO-related bypass for the permittee. Section 4.9.1 contains a detailed
discussion of CSO-related bypass, which is likely to be addressed in the special conditions
section of the Phase II permit.
3.5.1.8 Implementation Schedule
The permit should require the permittee to develop a schedule that will ensure timely
implementation of the selected CSO controls. The proposed CSO implementation schedule
should include construction schedules, financing plans, and milestones for any other permitting
requirements (e.g., environmental reviews, siting of facilities, site acquisition, and Army Corps
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Chapter 3 FJtoe 1 Permitting
of Engineers permits). These schedules may be phased depending on the following
environmental and financial factors:
* Elimination of CSOs to sensitive areas as the highest priority
» Use impairment of receiving water
* Permittee's financial capability, including consideration of such factors as:
- Median household income
- Total annual wastewater and CSO control costs per household as a percent of
median household income
- Overall net debt as a percent of full market property value
- Property tax revenues as a percent of full market property value
- Property tax collection rate
Unemployment
- Bond rating
* Grant and loan availability
• Previous and current residential, commercial, and industrial sewer user fees and rate
structures
* Other viable funding mechanisms and sources of financing,
EPA's guidance documents on LTCPs (EPA, 1995a) and financial capability assessment
(EPA, 1995e) contain information on scheduling and financial capability.
3.5.1.9 Post-Construction Compliance Monitoring Program
The post-construction compliance monitoring plan should be submitted by the permittee
as part of the LTCP and reviewed by the permit writer (see Section 4.5.2). The permit writer
should require that this plan detail the monitoring protocols and associated schedules (including
the duration of the different monitoring activities). The monitoring protocols should include the
necessary effluent and ambient monitoring and, where appropriate, biological assessments, whole
effluent toxicity testing, and sediment sampling.
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Chapter 3
The monitoring plan should include ambient monitoring at locations appropriate to
determine the Ml range of CSO impacts on the water body. The types of pollutants and
parameters to be analyzed, which will depend on the WQS in the receiving water body, might
include chemical (e.g., biochemical oxygen demand, total suspended solids, metals, oil and
grease, herbicides, and pesticides), physical (e.g., temperature, turbidity, sedimentation), and
biological (e.g., fish, benthic invertebrates, and zooplankton) parameters. The monitoring
should be coordinated with any ongoing or planned State monitoring programs and programs of
other permittees within the same watershed,
The permit writer should encourage the permittee to develop appropriate measures of
success as part of its monitoring plan. The permittee's measures of success should be based on
site-specific circumstances. Section 2.8 discusses potential measures of success for the CSO
program,
Because construction of the selected CSO controls may extend over several permit terms,
it might be appropriate to defer all or some requirements for development of the post-
construction monitoring plan to later permits when construction of the CSO controls is complete,
The permit writer may also consider requiring the permittee to conduct certain types of
monitoring (e.g., for specified parameters) for the duration of the permit and other monitoring
for a time period shorter than the permit term. EPA's guidance for monitoring and modeling
presents information on the development of a post-construction compliance monitoring program
(EPA, 1995d).
3.5.2 Schedule for Development of the Long-Term Control Plan
The permit writer should establish a deadline for completing and submitting the LTCP.
According to the CSO Control Policy, this deadline should be within two years of the effective
date of the Phase I permit or other implementation mechanism (such as an enforcement order).
As stated in the CSO Control Policy, the permit writer may extend the two-year deadline on a
case-by-case basis to account for site-specific factors that might complicate the planning process
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Chapter 3 ^ Phase I Permitting
for the permittee. A schedule for completion of the LTCP should be included in an appropriate
enforceable mechanism.
The permit writer should also consider establishing a periodic reporting schedule that
requires the permittee to report on progress related to LTCP development. These progress
reports should describe progress made to date on each of the primary LTCP components,
identify problems that might affect completion of the LTCP, and describe remedial measures to
be taken when necessary. Depending on the specific circumstances and complexity of the CSS,
a permit writer may require submission of progress reports on a regular basis (e.g., quarterly,
biannually), customize the schedule to track critical path components (e.g., to ensure public
participation occurs early in the process or that CSS characterization is proceeding), or require
the submission of progress reports at the completion of each component of the LTCP.
hi addition to progress reports, the permit writer should consider establishing interim
deadlines and deliverables for various components of the LTCP to ensure that the permittee is
making adequate progress during the term of the permit. Example permit language requiring
the submission of interim deliverables is provided in Exhibit 3-5, presented earlier. The
submission of interim deliverables prior to completion of the LTCP gives the permit writer and
other key participants, such as WQS authorities, an opportunity to review critical components
of the LTCP early in the planning process and avoid delays hi issuing the Phase II permit due
to the submission of inadequate information or analyses. Generally, EPA expects the permit
writer to receive the following interim deliverables prior to completion of the LTCP;
* Public participation plan
• CSS characterization, monitoring, and modeling plan
• CSS characterization, monitoring, and modeling results, including identification of
sensitive areas
* Identification of CSO control alternatives
* Evaluation of CSO control alternatives and cost/performance curves
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Chapter 3 Phase I Permitting
» Operational plan
• Proposed implementation schedule, including supporting analyses
* Post-construction compliance monitoring plan.
Upon receipt of an interim deliverable, the permit writer should work closely with the
permittee to ensure that any inadequacies or other issues arc addressed prior to submittai of the
final LTCP and issuance of the Phase n permit. Section 3.10 provides more detail on the
responsibilities of the permit writer while reviewing interim deliverables.
The specific deadlines in the permit or other enforceable mechanism will depend on the
circumstances of the CSS being permitted. For example, if a permit writer requires the
development of a public participation plan, the permit writer should impose deadlines for
completion of the plan and, after review by the NPDES permitting authority, for its
implementation. In other cases, the information, such as CSS characterization data needed to
identify sensitive areas, might not be available prior to issuance of the Phase I permit. Due to
the importance of evaluating alternatives to protect sensitive areas, the permit writer should
establish a deadline for the submission of information on sensitive areas early in the LTCP
development process.
3.5.3 Considerations for Previous or Ongoing CSO Control Efforts and Snail Combined
Sewer Systems
Generally, the permit writer should consider two special factors when establishing the
requirements to develop the LTCP: the permittee's previous efforts to control CSOs and the
limited resources of small communities,
3.5.3.1 Recognition 0f Previous or Ongoing Efforts at Controlling CSOs
The permit writer will probably determine that municipalities are at different stages of
CSO characterization and CSO control implementation. Some municipalities might have already
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Chapter 3 Phase I Permitting
begun planning, monitoring, and implementing CSO controls in response to EPA's 1989 CSO
Control Strategy and other initiatives.
The CSO Control Policy recommends that the permit writer consider, on a case-by-case
basis, the following efforts that a permittee might have undertaken prior to Phase I permitting:
1) substantial completion of construction of CSO controls that appear to provide for attainment
of WQS, 2) CSO control programs substantially developed or implemented pursuant to existing
permits or enforcement orders, and 3) previous construction of CSO control facilities designed
to provide for attainment of WQS but where WQS have not been attained due to remaining
CSOs.
If the permit writer has determined that the permittee has "substantial!) completed"
construction of projects designed to provide for attainment of WQS, the permit Conditions for
LTCP development may be modified to reflect these efforts. The permit unti" ma\ choose not
to require the initial planning and construction provisions of the LKT The permittee,
however, should be required to complete the relevant components of the 1 Iff* ifut might not
have been addressed by the permittee's previous efforts or that represent on.* nnj ^.nnmitments,
including development of an O&M program and post-construction comp!u:v.i- its »mtormg plan.
If subsequent monitoring shows that the WQS are not being attained arwi CS< K continue to
contribute to the impairment of designated uses or exceedances of u.tter quality criteria,
notwithstanding efforts to coordinate with WQS authorities, then an enforceable order should
require a re vised/amended LTCP, and the permit should be modified as appropriate.
If the permittee has substantially developed or is implementing a CSO control program
pursuant to an existing permit or enforcement order but has not completed construction of the
selected CSO controls, and the control program is expected to provide for attainment of WQS
and is consistent with the objectives of the CSO Control Policy, the permit requirements should
be modified to require evaluation of sensitive areas and financial capabilities, as well as
development of a post-construction monitoring plan.
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Chapter 3 Phase I Permitting
If the permittee has previously constructed CSO facilities in an effort to attain WQS but
has failed to meet the applicable standards because remaining CSOs are not sufficiently
controlled, the permit writer may consider these previous efforts when identifying further CSO
control planning activities. The previous construction of CSO control facilities, although not yet
attaining WQS, may mitigate the need to complete each step in the LTCP. In some cases, a
permit writer may need to require the development of a complete, although abbreviated, LTCP
(e.g., further CSS characterization might be needed or other alternative CSO controls identified
and costs and funding mechanisms developed).
3,5.3.2 Small System Considerations
The CSO Control Policy acknowledges that portions of the LTCP may prove to be
difficult to implement for small municipalities and recommends that for CSSs in jurisdictions
with populations under 75, (XX), the permit requirement to develop the LTCP should reflect the
capabilities of such "small" jurisdictions. The permit writer should ensure that the permittee has
gathered enough information to implement effective CSO controls. The permit requirements for
developing a plan should include consideration of sensitive areas, public participation in the
selection of the CSO controls, and a post-construction compliance rnonitormg program sufficient
to determine whether WQS are attained. Thus, for jurisdictions with populations less than
75,OCX), the permit writer may use discretion in deciding not to include specific requirements for
the following components of the LTCP: system characterization, monitoring and modeling;
evaluation and selection of alternatives (including cost/performance analyses); operational plans-
maximization of treatment at the POTW treatment plant; and implementation schedule. Overall,
the permit writer should be aware that a delicate balance needs to be achieved between resources
spent on monitoring and modeling and resources spent on implementation of controls.
3.6 EFFLUENT LIMITATIONS
The CWA requires that technology-based effluent limitations be established for all point
source discharges. In addition, a point source may also be subject to more stringent limitations,
including those necessary to meet WQS. During Phase I permitting, the permit writer should
establish technology-based requirements and any other limitations necessary to meet WQS in the
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Chapter 3 ^ Phase / Permitting
form of narrative requirements since he or she will probably not have sufficient data or
information to establish numeric effluent limitations. During subsequent CSO permitting phases,
as data and information related to the CSOs and CSO controls implemented by permittees
improve, it may be appropriate to develop numeric effluent limitations.
3.6.1 Technology-Based Requirements
Section 301 of the CWA requires effluent reductions based on various degrees of control
technology for all discharges of pollutants. For existing nonmunicipal dischargers, these
technology-based effluent limitations must reflect BAT/BCT for toxic, conventional, and
nonconventional pollutants.
NPDES regulations at 40 CFR 122.44(a) require the establishment of technology-based
effluent limitations for pollutants of concern discharged by point sources that will be regulated
under an NPDES permit. Although CSOs are subject to technology-based requirements, they
are not subject to secondary treatment standards applicable to POTWs. According to 40 CFR
125.3(c), in the absence of national effluent guidelines and standards for point source discharges,
technology-based effluent limitations are to be established on a case-by-case basis using the
permit writer's BPJ.
The CSO Control Policy recommends the use of the NMC, in the form of best
management practices (BMPs), as the technology-based requirements for CSOs. The use of
BMPs in lieu of numeric technology-based effluent limitations is allowed under 40 CFR
122.44(k)(2) where it is infeasible to calculate a numeric limit. BMPs are considered
particularly applicable for CSOs because the types, concentrations, and quantities of pollutants
expected from a precipitation event are generally unpredictable.
As stated in the CSO Control Policy, Phase I permits should at least require the permittee
to "immediately implement BAT/BCT, which includes the nine minimum controls, as determined
on a BPJ basis by the permitting authority." Thus, where the permit writer determines on a BPJ
basis that the implementation of the NMC in Phase I and Phase JJ permits meets the technology-
3-35 ' August 1995
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Chapter 3 Phase I Permitting
based requirements, he or she should not need to develop numeric technology-based effluent
limitations. Exhibit 3-3, presented previously, provides example permit language requiring
implementation of the NMC.
If the permit writer determines that numeric technology-based effluent limitations are
warranted for CSQs, EPA's Training Manual for NPDES Permit Writers (EPA, 1993) should
be consulted for guidance on developing limits on a case-by-case basis using BPJ, Although mis
EPA manual is intended to address continuous discharges, it may provide useful information for
wet weather flows.
3.6.2 Water Quality-Based Requirements
Section 301(b)(l)(C) of the CWA and NPDES regulations at 40 CFR 122 44 <»t permitting to
determine whether numeric water quality-based effluent limitations art- rxxoxar} This is due
to many factors including the lack of point source and ambient data tor u-mcnti >nal. loxic, and
nonconventional pollutants of concern. Thus, it is likely to be very diiiuuls .»r inappropriate for
the permit writer, at this point, to "back-calculate" effluent limits based en WQS.
As described in the CSO Control Policy, Phase I permits should at least require mat the
permittee immediately comply with applicable WQS expressed in the form of a narrative
limitation. Such a requirement to comply with narrative WQS is justified for CSOs if, prior to
the development of the LTCP, sufficient data are not available to evaluate the need for numeric
water quality-based effluent limits.
Exhibit 3-8 provides example permit language requiring compliance with narrative WQS.
The specific narrative standards a permit writer should include as permit conditions will depend
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Chapter 3 Phase I Permitting
on, and should be consistent with, State WQS. All State WQS have narrative criteria that
address aesthetic qualities (e.g., all waters shall be free from discharges that settle to form
objectionable deposits). Although State narrative standards can be incorporated into the permit
by reference, EPA recommends that the permit writer include the specific narrative language in
the permit to ensure that the permittee understands exactly what standards it must meet.
Exhibit 3-8, Example Permit Language for
Requiring Compliance with Narrative Water Quality Standards
L 'Effluent Limits ' '" ?•'$• '•'•• , -.-.. . . .'
';' .;.-.-" , .
B. Water 'quality-based requirements for CSOs. • '• "'•.
..:::K The permittee, sfeaD not discharge any ...pollutant' 'at a level that: causes or contributes to an: j
|| excursion above numeric or narrative 'criteria developed- and adopted as /part • of {Insert • State namej water
quality standards, • " :' ,v ;'"' ' ": :i: •-• . ' ^ . ~- . • '•'-
•Site-Specific Language; • . "\ •' • ' : •-.•'•.''.•
.-.':•'. . f ' • ' •: ••
/. The'' permittee- shall not discharge -any 'floating debris,, oil, 'grease, scum, foam, or Mher -.objectionable
'. materials- tfut may. result .in amounts -sufficient to 'be unsightly or otherwise objectionable or to •
. •• constitute a"nui$ance under-State .faw.- -: ••.".- • ; .-.'...-..•.••
2.; Jhe-.-permittee. shall not discharge .fefffea^le -solids* sediments, sludge deposits, or suspended
' particles that may coat or cover su&merged surfaces, ' . . .....-.•
3. The permittee shall not discharge any pollutmts iftof msy impart, undesirable adors* tastes,' or '. . •
colors to the receiving water body'- or to the -aquatic tife fiwftd'' therein, wary endang& public -health^
or may- result in the domitiance ofaut^ance species.- •
3,7 MONITORING
Phase I permit monitoring requirements should address both NMG implementation and
LTCP development activities. Under the NMC, the CSO Control Policy recommends
monitoring to characterize CSO impacts and to determine the efficacy of CSO controls. The
objectives of such monitoring include the Following:
» To map the drainage area for the CSS
* To identify all CSO outfall locations and develop a record of overflow occurrences
(i.e., total number, frequency, and duration)
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Chapter 3 ^ Phase 1 Permitting
* To compile existing information about the receiving water (e.g., existing uses and
water quality criteria) and whether WQS are currently being attained in the water
body
* To compile existing information on water quality impacts associated with CSOs
(e.g., beach closing).
The information collected as part of this control should be used to establish baseline
conditions both prior to and subsequent to implementation of the NMC. Exhibit 3-3, given
previously, presents example permit language for the NMC morutoring requirement.
The second aspect of Phase I monitoring is CSS characterization as part of LTCP
development. The objectives of such monitoring include the following:
* To obtain a thorough understanding of the CSS, including its response to various
precipitation events
* To evaluate the impacts of CSOs on the receiving water
* To assess the effectiveness of various CSO control alternatives in reducing the
impacts of CSOs on the receiving water.
Exhibit 3-5, given previously, contains example permit language for the monitoring
requirements associated with LTCP development. During LTCP development, the permittee
should prepare a monitoring and modeling plan to be reviewed by the NPDES permitting
authority and other members of the review team (see Section 3.10) before conducting monitoring
and modeling activities. This review should ensure that adequate but not unnecessary
information and data are collected to support LTCP development and the review and revision,
if appropriate, of WQS to reflect site-specific wet weather conditions.
The permit writer and permittee should not view monitoring conducted as part of NMC
implementation and LTCP development as independent activities, but rather as related
components in the CSO control planning process. In many cases, the permittee will be
conducting NMC implementation and LTCP development concurrently. Thus, where monitoring
objectives overlap, the permit writer should coordinate the monitoring requirements into one
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Chapter 3 Phase I Permitting
comprehensive permit condition. For example, the permit writer could put all monitoring
requirements into one section of the permit.
In some cases, monitoring associated with the NMC and the LTCP might require special
characterization studies (e.g., if existing site-specific information implies that CSOs are causing
substantial water quality impacts). These studies might include the following:
• Sediment studies
* Whole effluent toxicity testing
* Biological assessment.
This type of monitoring can be required as a short-term study special condition.
Typically, such a study is required in response to specific information indicating that the CSO
is impairmg the designated use or water quality. The permit writer might want to develop
permit conditions that require 1) a separate monitoring plan to be developed for each special
study, 2) the plan be submitted for review prior to performing the monitoring, and 3) me final
report to be submitted to the NPDES permitting authority within a specified time after study
completion.
The permit writer should review the monitoring plans carefully to ensure that the CSO
information collected can be correlated with water quality impacts; otherwise, the studies might
not provide conclusive evidence of the cause of impact. Other studies might be needed in
conjunction with these special studies. For example, sediment studies might not be meaningful
without a contaminant transport modeling study, and a bioassay might not provide meaningful
results without toxicity data and CSO data. The permittee should include appropriate quality
assurance/quality control procedures as part of these studies to ensure that the results can be
verified. EPA's guidance on monitoring and modeling contains additional information on these
types of studies (EPA, 1995d),
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Chapter 3 ^ ^ ^ Phase 1 Permittwg ,
3.8 REPORTING
Reporting requkements related to CSO controls that should be included in the Phase I
permit fall into two categories: 1) documentation of NMC implementation and 2) LTCP
development. Exhibit 3-4, presented previously, provides example permit language, and Section
3.4.2 contains a detailed discussion of the recommended reporting requkements associated with
the NMC. Section 3.5 discusses the recommended LTCP interim deliverables, as well as the
requirement to submit the completed LTCP, and provides example permit language.
In addition to the CSO control-related reporting mentioned above, permittees should be
required to periodically report the results from monitoring requirements established in the
permit, including any special monitoring studies.
3.9 • SPECIAL CONDITIONS '
This section discusses two special conditions. The first, CSO-related bypass, should be
used in certain limited circumstances to authorize bypasses under 40 CFR 122.41(m). The
second special condition, a reopener clause, should appear in every permit covering CSOs.
3.9,1 CSO-Related Bypass
Some POTW treatment plants might have existing primary treatment capacity that
significantly exceeds secondary treatment capacity. The CSO Control Policy recognizes that
40 CFR 122.41(m) can be interpreted to allow an advance authorization of a CSO-related bypass
in the NPDES permit to take advantage of the opportunity to provide at least primary treatment
of most or all wet weather flows. The CSO Control Policy envisions that the permittee would
evaluate the feasibility of this as part of the LTCP; for this reason, this special condition is most
likely to occur in the Phase II permit. If the permit writer believes that a CSO-related bypass
might be an effective CSO control available for use in the Phase I permit, however, he or she
should require the permittee to submit the necessary information as part of the permit
application. Section 4.9.1 contains a detailed discussion of CSO-related bypass.
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Chapter 3 Phase I Pemuttmg
3,9.2 Permit Reopener Clause
As with any NPDES permit, the permit writer should include an appropriate reopener
clause. Exhibit 3-9 provides an example reopener clause generally appropriate for a Phase I
permit. This reopener language allows the permit to be modified or revoked and reissued to
incorporate requirements to implement selected CSO controls in advance of the normal permit
reissuanee. This will assist the permit writer in accelerating the implementation of selected CSO
controls. The permit writer should evaluate this language carefully to ensure that it is
appropriate for the permittee. The permit writer might decide that the generic reopener clause
already included in NPDES permits is sufficiently broad to address CSOs,
Exhibit 3-9. Example Permit Language for a Phase I Eeopener Clause
This pennit may be modified ortevotoed.and reissued, as provided -pucsaant to-40 CFR.-122.162.'and'124,5,
.for-the following reasons: " .•/".'. "• "
* To include new:. or revised conditions 'developed 'to comply with. any State-orFederal-.:law0r
s regulation- that addresses CSCte. taat is, adopted orpronmlgated sifoseqnent to tlte•ei$^ve.dale.of••
< •; this permit • • . . ..' ' ' "• :; '. ' • • .':'.:'-'V • ' _ '-?.- '..;_• •: '• v.;:
..... * To- iaclude new or revised- conditions if new- information, not available -a toe-time of peitutjssuaiice.< .•
indicates thai CSO cdmrols ''imposed -under -flje .-permit' .have failed to .ensure the attainment of -State' • '
;. water: cjuafity standards. '• • ' - ' v '•'.....-. . ' • • " ."" '':
* To. include .new or revised -conditions based on- new information -generated'- farta ihe long-term -coattol
""
to additi'0ft, this pennit may -be modified :or'.ievoked and . reissued .for any- reason .specified ''in 40':CFR .
122.62. - ;S :1 ,* ^ ' ' ' - ' L- ' - .' ' '• ..... •'
3.10 ADDITIONAL ACTIVITIES DURING PHASE I PERMITTING
The permit writer should be responsible for ensuring the receipt and coordinating the
review of NMC documentation and all interim CSO-related documents submitted as part of the
LTCP development. This will enable the permit writer to begin evaluating the permittee's
progress in implementing the NMC and developing an LTCP. The early review during Phase
I will assist the permit writer in identifying and resolving issues prior to the development of the
Phase II permit. If the review of progress made by the permittee during the Phase I permit term
is not performed until just prior to the development of the Phase II pennit, significant delays
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Chapter 3 ^ ^ pjua* I Permitting
might occur, particularly if a permit writer detects extensive deficiencies in the progress made
by the permittee.
To ensure that the NMC documentation and all LTCP deliverables are reviewed properly
and to facilitate the expeditious review of these submissions, the permit writer should coordinate
among appropriate representatives of the NPDES permitting authority, and should establish a
review team made up of NPDES permitting and enforcement personnel. State WQS personnel,
and State watershed personnel (see Section 4.5.1). The permit writer should identify team
members and coordinate with them to review the NMC documentation and LTCP interim
deliverables. The review team may also be useful in assisting the permit writer in developing
permit conditions.
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CHAPTER 4
PHASE D PERMTTTING
This chapter provides the permit writer with guidance related to developing and issuing
the Phase II permit. It also discusses the review and evaluation of documentation that should
generally be required by the Phase I permit.
4.1 PHASE n PERMIT
The primary objective of the Phase II permit should be to require the permittee to
implement the selected combined sewer overflow (CSO) controls in the long-term control plan
(LTCP) that will meet Clean Water Act (CWA) requirements. After the permittee has
completed the development of the LTCP and has discussed and coordinated the selection of the
necessary CSO controls with the permit writer, the State water quality standards (WQS)
authority, and the public, the permit writer can embody the selected CSO controls into the Phase
n permit.
To be consistent with the CSO Control Policy, the Phase n permit should generally
contain provisions that:
* Require the permittee to continue implementing the nine minimum controls (NMC)
* Direct the permittee to implement and properly operate and maintain the selected
CSO controls from the LTCP
* Require the permittee to implement a post-construction water quality monitoring
program
* Require the permittee to periodically reassess overflows to sensitive areas where
elimination or relocation was not feasible
* Authorize the National Pollutant Discharge Elimination (NPDES) permitting authority
to reopen and modify or revoke and reissue the permit when the CSO controls do not
result in attainment of WQS.
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Chapter 4 Phase II Permtitmg
The permit writer should coordinate the development of the Phase E pennit with the
permittee and the State WQS authority to ensure that statutory and regulatory requirements are
met. The permit writer should also ensure that the general public is involved in the decision-
making process leading to fmalization of the Phase E pennit conditions through the public notice
provisions of the NPDES permit regulations or the equivalent provision in approved NPDES
State permit issuance programs.
In drafting the Phase n permit, the permit writer should work closely with the permittee
and the State WQS authority in reviewing the CSO control alternatives presented in the LTCP.
The permit writer should ensure that the permittee has shown, using either the presumption or
demonstration approach, that the selected CSO controls will provide for the attainment of WQS
in the receiving water body.
For the technology-based requirements in the Phase n permit, the permit writer should
require continued implementation of the NMC as appropriate. The permittee's documentation
may be used to show that the NMC continue to satisfy best available treatment economically
achievable (BAT)/best conventional pollutant control technology (BCT) requirements on the basis
of the permit writer's best professional judgment (BPJ). The permit writer may choose to
modify any or all of the NMC from the Phase I permit to be more site-specific, based on the
documentation submitted by the permittee. For the water quality-based requirements in the
Phase n permit, the permit writer should require implementation of the CSO controls in the
LTCP. The permit writer must document in the fact sheet or statement of basis how the Phase
n permit meets the technology-based and water quality-based requirements of the CWA.
4.2 INFORMATION NEEDS
To develop a Phase II permit, the permit writer should rely on information and data that
the permittee has submitted in response to Phase I permit requirements. This includes 1) the
documentation showing the permittee's implementation of the NMC, 2) the LTCP, including any
interim deliverables submitted during the LTCP development, and 3) any other information
required by the Phase I permit. In most cases, the permit writer will need this information, at
4-2 August 1995
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Cftqpftr 4
Phase If PermMng
a minimum,, to develop an effective Phase II permit. If this information is not adequate, the
permit writer should request additional information from the permittee, Section 3,2 describes
available mechanisms for obtaining additional information and data.
4.3 IDENTIFICATION OF CSO OUTFALLS IN THE PERMIT
The locations of ail CSO outfalls should have been documented prior to issuance of the
Phase II permit. Therefore, the permit writer should specifically identify CSO outfalls in the
Phase II permit. Exhibit 4-1 provides example permit language for authorization to discharge
from CSO outfalls. The permit writer should evaluate this language carefully to ensure that it
is appropriate for the permittee.
Exhibit 4-1. Example Penult Language for Identifying CSO Outfalls
in a Phase H Permit
HeperaiiRee:is.'»ttai2ed to discharge 'jfea.the,;ou.tM:lsristed:-l>elow'0i accordaik«- «.stf tjw requirements
aad other r*"-:.:«fr
•Overflow J&famber •
. number]
Overflow 'Outfall. •Location'
.|ins«i;lafiftHl'ertoiigita«te
.(street adSress spttoaai)]
'- "*. ..... Uj>'n
Iin>eri
water body]
4.4 MINIMUM CONTROLS •
The permit writer should determine whether the permittee's actson^ io implement the
NMC under the Phase I permit are adequate to meet the technology based requirements of the
CWA. This can be accomplished by reviewing the information provided b> the permittee during
the Phase I permit term (i.e., NMC documentation and the LTCP). Section 4.4.1 discusses
recommended evaluation criteria. The Phase II permit should, as appropriate, require continued
implementation of the NMC. When preparing the Phase II permit, therefore, the permit writer
should develop permit language requiring the continued implementation of the NMC (including
site-specific language, as appropriate) and its associated documentation. Section 4.4.2 provides
example site-specific permit language.
4.3
August 1995
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Chapter 4 ^ ^ Phase II Permitting
4.4.1 Review of Permittee's Implementation of the Nine Minimum Controls
As discussed in Section 3.10, the permit writer, in conjunction with other appropriate
personnel, should review the NMC documentation for completeness and compliance with Phase
I permit requirements. The documentation serves as the basis for the development of
technology-based requirements in the Phase II permit, on a BPJ basis reflecting site-specific
considerations. If a permit writer determines that certain components are incomplete or not
properly addressed by the permittee, then the permit writer should follow up with the permittee
in one of two ways. If the permit writer believes that missing or incomplete components are
relatively significant and that the permittee has not acted in good faith to submit the
documentation, then the permit writer may coordinate with enforcement personnel to initiate an
enforcement action for noncompliance with a Phase I permit condition. If only minor
components are unclear or incomplete, the permit writer may simply request the missing or
incomplete data from the permittee in accordance with the policies and procedures of the NPDES
permitting authority (e.g., informal telephone request or formal request letter).
After receiving the completed documentation, the permit writer should evaluate whether
the actions already taken or being taken by the permittee are adequate to meet the NMC
requirements in the permit. This section recommends some general criteria under which the
permit writer can evaluate the adequacy of the permittee's NMC, Because of the site-specific
nature of the control measures, these criteria are not aU-inclusive but provide a basis for
evaluation by the permit writer. EPA's Combined Sewer Overflows—Guidance for Nine
Minimum Controls contains additional detail on the NMC (EPA, 1995b),
The permit writer should review the NMC documentation using the criteria recommended
in the following paragraphs (also provided in checklist form in Appendix C). The permit writer
should note that not all the criteria will apply to each permittee. Applicable criteria are based
on the control measures implemented by the permittee.
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Chapter 4 Phase II Permitting
4.4.1.1 Proper Operation and Regular Maintenance Programs for the CSS and CSO
Outfalls
When evaluating the permittee's operation and maintenance (O&M) program, the permit
writer should consider whether the program:
» Describes the system, including an inventory of all CSO structures, equipment, and
treatment facilities. Provides procedures for keeping this inventory current.
« Includes routine inspection, cleaning and maintenance, and repair schedules for all
inventoried CSO outfalls, interceptors, regulators, pumping stations, and equipment.
Includes schedules and inspection frequencies that are appropriate for the system.
* Includes inspections for dry weather overflows and illicit connections.
• Provides operating procedures and specifications for all equipment, structures,
facilities, CSO outfalls, and off-line storage structures. Describes the hydraulic
capacities of the coEection and treatment systems, the storage capacities of the
collection and treatment systems, and off-line storage capacity.
• Has in place operating procedures that reflect the best use of the system's flow and
routing controls to minimize CSOs. Includes procedures to identify and correct
combined sewer system (CSS) and CSO problems.
* Requires logs or other documentation of completed activities and documentation of
sewage blockages.
• Addresses the location of overflows where O&M is hindered (e.g., structures are
under major thoroughfares, railroad yards, or other difficult-to-reach or safety hazard
areas).
* Allocates resources for O&M program implementation, including staffing level and
funding, equipment, and training.
* Will be effective in reducing the number, frequency, and pollutant loadings of CSOs.
Note that an operational plan is also a component of the LTCP. The O&M program
developed as part of NMC implementation essentially becomes the operational plan (i.e., the
revised O&M program that includes the permittee's selected CSO controls). Thus, the
operational plan can be reviewed using the above listed factors.
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Chapter 4 Phase II Permitting
4.4.1.2 Maximum Use of the Collection System for Storage
The permit writer should consider whether the permittee has;
• Identified portions of the CSS usable for storage and determined the CSS storage
capacity, including configuration, size, and pump station capacity
« Identified appropriate minor modifications to increase storage (e.g., raising existing
weirs)
* Identified potential off-line storage at existing facilities
• Implemented procedures for maximizing CSS storage capacity.
The permit writer should note that this control measure might increase the possibility of
"upstream" problems, such as basement flooding, and mat the potential tor a permittee to
increase collection system storage varies. Increased sedimentation in the colk*au>n system, mote
frequent cleaning, odor potential, and other factors should be considered ut»cr evaluating the
potential for collection system storage.
4.4.1.3 Review and Modification of Pretreatment Programs
This control applies primarily to permittees with approved pretrcjinu-nr programs. If the
permittee does not have an approved pretreatment program, however, 11 should nevertheless
attempt to determine whether nondomestic sources are contributing u> CSO impacts. In
evaluating the implementation of this control, the permit writer should con>tJcr whether the
permittee has:
* Determined whether the CSS receives nondomestic wastewater discharges.
* Prepared an inventory of nondomestic users who discharge to the CSS. Evaluated
the discharge constituents and suspected impacts from such users.
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Chapter 4 Phase II Permittmg
Evaluated the potential for regulating either the volume or pollutant loadings from
nondomestic users to the CSS during wet weather flow conditions. The evaluation
should include a discussion of whether the modifications are feasible or of practical
value for CSO control, For example, the permit writer might evaluate whether the
permittee has considered requiring nondomestic users with appropriate storage
capacity to temporarily hold wastewater during precipitation events or when notified
by the permittee or has considered prohibiting new users from discharging storm
water or uncontaminated water, such as non-contact cooling water, to the collection
system,
Modified the pretreatment program if appropriate.
4.4.1.4 Maximization of Flow to Publicly Owned Treatment Works Treatment Plant
The permit writer should consider whether the permittee has:
f
* Compared existing flow conditions to the design capacity of the collection system
* Identified actions that could be taken to increase flows to the publicly owned
treatment works (POTW) treatment plant during wet weather flow conditions without
significantly affecting treatment performance
* Conducted tests to determine the plant capability to treat higher flows during wet
weather flow conditions or determined, using available historical data, the maximum
flow that can be treated
* Developed, implemented, and documented implementation of a flow maximization
plan during wet weather flow conditions.
4.4.1,5 Prohibition of CSOs During Dry Weather Flow Conditions
The permit writer should consider whether the permittee has:
* Developed adequate procedures to document where and when dry weather overflows
occur, including follow-up inspections after dry weather overflows occur
* Developed md Instituted procedures to prevent and eliminate dry weather overflows,
including routine inspection of regulators and CSO outfalls, as part of the O&M plan.
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Chapter 4 Phase II Permitting
4.4.1.6 Control of Solid and Floatable Materials in CSOs
The permit writer should consider whether the permittee has:
» Evaluated the following technologies for the control of solid and floatable materials
in CSOs: screening materials using baffles, screens, and netting; skimmer boats;
skimming from water body surface with booms at outfalls in confined areas; and
source control, which may be addressed under the pollution prevention program for
CSO outfalls (see Section 4.4.L7—Pollution Prevention Program)
* Identified and addressed problems that might be created by the installation of the
control technology
* Implemented the appropriate control technology. considered and provided justification
that the technology is appropriate for the site conditions, and is conducting associated
inspections and regular maintenance.
4,4.1.7 Pollution Prevention Program
The permit writer should consider whether the permittee has:
* Evaluated source control measures both at the government level (e.g., street cleaning;
banning or substitution of products, such as plastic food containers; controlled use of
pesticides, fertilizers, and other hazardous substances at public facilities) and among
the public (e.g., used oil recycling, household hazardous waste collection)
» Included a wide-reaching public education program
* Evaluated mechanisms to encourage water conservation (e.g., public outreach,
structuring of water/sewer service charges, local ordinance provisions)
* Allocated adequate resources to conduct pollution prevention program activities
» Implemented and maintained detailed records of pollution prevention activities
* Promoted the use of industrial/construction best management practices (BMPs) for
storm water.
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Chapter 4 Huge II Permitting
4.4.1.8 Public Notification
The permit writer should consider whether the permittee has:
• Evaluated options to ensure that the public receives adequate notification of CSO
occurrences and CSO impacts
• Implemented notification procedures regarding the presence of contaminants at critical
levels in the receiving water bodies due to CSOs
* Implemented procedures that notify persons reasonably expected to be affected by the
CSO
» Documented CSO occurrences and associated notifications
« Installed identification signs at each CSO outfall.
4.4.1.9 Monitoring to Effectively Characterize CSO Impacts and Efficacy of CSO
Controls
The permittee is likely to have conducted monitoring recommended for this minimum
control in conjunction with CSS characterization associated with the LTCP development. Thus,
the permit writer should review the permittee's monitoring efforts as a whole and assemble all
applicable monitoring data prior to the evaluation. In evaluating the permittee's monitoring data,
the permit writer should consider whether the permittee has:
• Characterized the CSS to identify all CSO locations and receiving water bodies
* Collected data on the total number of overflow events and the frequency and duration
of CSOs for a representative number of CSO events
« Collected water quality data and information on chemicalt physical, and biological
impacts resulting from CSOs (e.g., beach closings, floatabies, wash-up episodes, fish
kills, impaired habitat for aquatic life)
» Conducted monitoring to determine baseline conditions prior to implementation of the
NMC
* Conducted monitoring to determine baseline conditions subsequent to implementation
of the NMC, which may be used in LTCP development.
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Chapter 4 Phase II Permitting
It is important to note that the permittee should be considering its NMC measures
collectively using a holistic approach—that is, it may be possible to satisfy two or more of the
NMC through a single control measure.
4.4.2 Permit Conditions
Once the permit writer has evaluated the permittee's NMC implementation and
documentation efforts, he or she should, where appropriate, develop Phase n permit language
that requires the continued implementation of the NMC. The permit language should be tailored
to the permittee's specific circumstances and should incorporate site-specific implementation and
recordkeeping requirements. The permit writer might need to coordinate the development of this
permit language with the LTCP implementation language because it is possible that some of the
NMC control measures will be incorporated into the LTCP as selected CSO controls or that
some NMC control measures might DO longer apply when the selected CSO controls have been
implemented (e.g., if the system is being separated).
The permit writer should establish technology-based requirements in the Phase n permit
based on the permittee's documentation of the NMC and any revisions resulting from
development of the LTCP, Exhibit 4-2 provides example permit language for each of the NMC.
The permit writer should evaluate this language carefully to ensure that it is appropriate for the
permittee. A portion of this language should be applicable to all permittees implementing each
particular minimum control. Additional site-specific language, which should be tailored to the
specific control measures implemented by the permittee, is given in italics. Although the site-
specific language might not be appropriate for all permittees, it is provided as an example of the
type of language and detail appropriate for requiring implementation of the NMC in the Phase
n permit. The permit writer may be able to select language directly from the permittee's NMC
documentation or LTCP and incorporate it into the permit. Although this guidance presents
numerous examples of site-specific permit conditions, it may be appropriate in some cases to
write broader conditions. This would provide sufficient flexibility to allow the permittee to
identify and implement other controls that are equally or more protective without the need to
modify the permit.
4-10 August 1995
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Chapter 4
Phase H Pemuttittg
Exhibit 4-2. Example Permit Language for Continued Implementation
of the Nine Minimum Controls
A.
- Effluent Limits .- .,,, -.<-. """""" j* ••'"• '-• ',,•> ' ... ^::\:1-;|!^= <
Tectraology-bsfied. requirements For CSOs. "Use permittee-, shall comply wilts die. following technology-
based requirements: ••; , • |||.. :'. . , ' >- '' ' . • >- t
-1. •Conduct proper operations and: regular.. mamMitmeeigrogyffliis:. 'The permittee shall implement .fte
•" operation and maintenance plan for the 'CSS 'thai will include the elements listed below-. The - '
permittee also shall update the plan' t0. incorporate -any changes to the system and shall. operate and
^ mMntain the system according to -the pSaa. The permittee -shall keep records -to document the
s implementation of the plan,' J-... , ..,:,••• ' " .' ...:.•
Site*Spedfi c Language:- "->='.•"" *...,,.. ^;-:V ,.,. ,, : ' .. ' . , '• ' ;,
, .. ::':;^' ;:;': ;;«V ;!|?: '. '• ... " • .. .*'-''
Designation .-of. a Maaaeer_fyr Combined SewerrSy$tem^ The permittee 'shall designate a person to
be responsible for the wastewaler collection., 'system md-'serve m the contact person, ••regarding the
• • • - •
Inspection and M&intenanee of CSS. The permittee sfyM. inspect. and nutinuetn'oll-CSO. '*
--structures, regtdtUQrs:t pumping statfonsf:and-tidegates to:ensure. that' they 'O&--mgop4'.working
'condition . and 'adjusted to minimize CSOs .mid prevent'- tidal] inflow. The pemime -shall- ' : |
inspect, or cause, to be inspected, mch.CSOmtfall:ai'.ait'Qppr^ruttefre^ency-to,.eMSttre-:nQ- "•
dry veather overflows :are occurring, Theinspeaions]^f:mdude,buth-'notUmtM'iot
ottering the regulator, ftruaare if accessible, determining the- extent &f:debris 'met. grit buildup,
and -removing any debris rte may- -consrrict flow, cause Modsage, -or result in a. dry -weather- .,
overflow. -The' permittee shall record in a maintenance 'fog -book 'the results rf ^..inspections.
For. CSO outfalls that are. inaccessible, the. permtme :«my-per/0rmn visual ''ches3c':'of.ihe
• overflow pipe -to determine whether of -not the -CSQ is occumng- during 'dry. veather flaw • .-
conditions. " . -._,.,' i- ""..-•-••:' .-, •' ' " .'
Provi-sion for Trained- -Staff,- The permittee shall emure:-the. avmtoMtify -af&Qmed.Maff. to ' ;
cany om the operation, 'maintenance^ repair, 'and -testing junctions required' 'to' ensure
compliance with the terms .and conditions of this permit. . -'Eack staff member shall -receive
appropriate training* . • ."•'.__ , ..--." > ... . . • . "-:•:•
Allocation of Funds- for Q
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Chapter 4
Phase II Permitting
Exhibit 4-2. Example Permit Language for Continued Implementation
of the Nine Minimum Controls (continued)
jiM^
:|eMW
'^
ion: and implementation of ffie seleaed
The permittee shall
fl^jptt^^
• &:|
M^»i^^|y^
?^
v:-r5l^
e|i^ ii ?|
t^x^iii^;5^^
............................... ' '"
tal^lasGS^SiJ'-' 3$^;|ifFiii:i^^
mm •yftiee-jo -^n^ftlm^^^^s:^^^^^
^^iu^^j^t^.t^jMu^^^^sii^ ;%;;S
4-12
August 1995
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Chapter 4 Phase II Petmittmg
Exhibit 4-2, for
of the Nine Controls (continued)
imp^g|«tM^g§o^^!^Qttfonprogrant;i>-''ltfe fenpftte- sfcalL
ftguaad.on. fte of CS0s,«n:teeeiwng wates. . Jhc
to HkaBneotpottmtioa- pret^iaa-.-impfenaii^ OB aetivkfck. ' " •' :
Site-Speafljt Laaguag®;
Street
f^
'A ^ro
Ttee-jperaiitiee shall o^tiniki^^in^lflaaeat a
•fe.; .. A>$ptesit0i«ennliiett3ie'-naSfflFe'att4duiatiffla;tff*|Sffiyistisat-aiiejxiieotiffl^llMiifriW-fe'
Jy tisers ol ftefce f
Tie dial]
' Wftiia J of the of'Ms fffnait* ihe'.peratitte®
ftGetimMgn$-«a aO':£5<@:oa$it$ cnimed.and'^pa^t^^ify Ot
. the. stgKt-at-er nmrAe-'C^./s^atts md «3wefMi<«fe,s%»$ are--easily.
s&all regularly moaiteF CSQ outfalls to eifecmfely characterize. GSQ impacts and fc: efficacy of
4-13 1995
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Chapter 4 Phase II Permitting
Exhibit 4-2 does not provide site-specific permit language for the ninth minimum control:
monitoring to effectively characterize CSO impacts and efficacy of CSO controls. This
monitoring should be integrated with the monitoring requirement to be placed in the Phase H
permit associated with implementation of the LTCP. Section 4.7 contains information on
developing permit language for these monitoring requirements.
4.4.2.1 Documentation for Fact Sheet/Statement of Basis
As required in 40 CFR 124.7 and 124.8, a fact sheet (or a statement of basis for minor
discharges) must be prepared for every NPDES permit. The purpose of the fact sheet is to set
forth the principal technical facts and the significant factual, legal, methodological, and policy
questions considered in preparing an NPDES permit. Although 40 CFR 124.8 establishes the
minimum requirements for a fact sheet, each permit writer should follow the format used by the
NPDES permitting authority.
The fact sheet must discuss the basis of all Phase II permit conditions requiring
implementation of the NMC. The permit writer should use the permittee's NMC documentation
to record in the fact sheet the justification for implementation of the specific minimum controls
chosen by the permittee. Further, when NMC are imposed in a specific permit, the permit
writer should discuss the fact that the NMC are being used to comply with the technology-based
requirements of the CWA (see Section 3.6.1). EPA's Training Manual for NPDES Permit
Writers contains more information on preparing a fact sheet or statement of basis (EPA, 1993).
4.5 LONG-TEEM CONTROL PLAN
The permit writer will generally be responsible for reviewing interim deliverables (see
Section 3.5.2) and for working closely with the permittee to ensure that any inadequacies,
problems, or issues are addressed in a timely fashion prior to submission of the completed
LTCP and the development and issuance of the Phase II permit.
In preparing for the development and issuance of a Phase II permit, the permit writer
should review the LTCP submitted by the permittee. After reviewing the LTCP, the permit
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Chapter 4 ^ Phase II Permitting
writer should require, where appropriate, implementation of the selected CSO controls Identified
in the LTCP. The primary responsibility of the permit writer in developing Phase II permits
is to ensure that the CSO controls proposed by the permittee comply with the requirements of
the CWA, including attainment of WQS. The requirement to implement these controls should
be appropriately reflected as enforceable NPDES permit conditions or included in another
enforceable mechanism. This section provides guidance on how to review the LTCP and
develop permit conditions to implement the LTCP.
4.5.1 Review of Long-Term Control Plan
The permit writer should form and coordinate a review team thai will he responsible for
reviewing the LTCP and ensuring that CWA requirements will be met. An appropriate review
team should include:
* WQS personnel to assist in evaluating proposed CSO control* ar>J to review and
revise State WQS, as appropriate. WQS personnel can alv» a^i^t in evaluating any
ambient or special monitoring conditions (e.g., toxicity icstim- • ttu* nu\ be required
during the term of the Phase II permit to monitor the efti-cma*.-^ <'n o! the selected
CSO controls. This will be particularly important if exiensiu- time i- required by the
permittee to comply with Phase II permit requirements.
* Field personnel to help review monitoring plans and assist in the dc\ cloprnent of CSO
monitoring requirements.
* Watershed personnel to ensure that the permittee's CSO control efforts are
coordinated with other point and nonpoint source control efforts within the watershed.
The review team should also include other types of personnel, as appropriate, depending on the
site-specific situation.
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Chapter 4 Phase II Permlttmg
As discussed in Section 3.5.2, the permittee is likely to have submitted parts of the LTCP
as interim deliverables during the Phase I permit term. The permit writer and other members
of the review team should review these deliverables, as well as the completed LTCP detailing
the permittee's selected CSO controls, as soon as they are submitted.
Upon receipt of the LTCP, the permit writer should first determine whether it complies
with the requirements hi the Phase I permit. After initial review of the LTCP, if a permit writer
!
determines that certain components are incomplete or are addressed improperly, the permit
writer should follow up with the permittee. Section 4.4.1 presents information on followup
procedures.
The permit writer, with support from other review team members, should review the
LTCP to ensure consistency with the CSO Control Policy and to ensure that the selected CSO
controls are reasonable and will result in compliance with CWA requirements. Of the various
CSO control alternatives considered by the permittee during LTCP development, the LTCP will
identify one or a combination of CSO controls for implementation. The LTCP should discuss
all of the alternatives arid, more importantly, why the selected CSO controls were chosen.
There should also be a discussion related to the selected CSO controls, including maximization
of treatment at the POTW treatment plant; the operational plan; integration of the NMC;
monitoring; costs of the selected CSO controls and financing; and the implementation schedule,
possibly including identification of milestones where re-evaluation and modifications would
occur. All other parts of the LTCP, including the CSS and water quality characterisation
monitoring and modeling used during the development process, the other alternatives and costs,
and public participation, ultimately become "historical" material that should not be addressed
in the Phase II permit, because they are not part of the selected CSO controls. This information
is generally critical for appropriate review of the LTCP, however.
The remainder of this section presents questions the permit writer should consider while
reviewing the LTCP. These recommended evaluation criteria are also provided in a checklist
hi Appendix D. These review questions are based on the provisions of the CSO Control Policy
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Chapter 4 Phase II Permitting
and the guidance provided in the Combined Sewer Overflows—Guidance for Long-Term Control
Plan (EPA, 1995a). Although the permit writer may use these questions as the basis for review,
he or she may need to supplement them to reflect the site-specific Phase I permit conditions
established for a particular permittee. For example, if a Phase I permit specifically required
monitoring and evaluation of certain pollutants of concern, then the permit writer should ensure
that the permittee has addressed these pollutants in its monitoring plan.
In reviewing the LTCP, the permit writer should remember that the level of detail in the
LTCP can vary significantly depending on the permittee and its CSS. The overall intent of the
review is to ensure that the LTCP is a coherent, organized document and that the permit writer
can follow a logical step-by-step analysis that justifies selection of the CSO controls.
4.5.1.1 Public Participation
When evaluating the public participation element of the LTCP, the permit writer and
other review team members should consider the following evaluation questions to ensure that the
proposed plan, once implemented, will result in an effective public participation program:
» Does the public participation process seek to actively involve rate payers, industrial
users of the CSS, persons near the affected waters, and persons who use the affected
waters?
• Does the public participation plan document how the public was notified of public
participation events?
• Does the public participation plan include a record of the public participation events,
including the number of people attending and a record or summary of comments?
• Does the public participation plan contain a summary of comments and the changes
or decisions made in response to public comments?
4.5.1.2 CSS Characterization, Monitoring, and Modeling
When the permittee submits a proposed monitoring plan as an interim deliverable during
LTCP development, the permit writer and other team members should review it to ensure that,
4_17 August 1995
/it
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Chapter 4 Phase II Permitting
once implemented, the proposed plan describes an effective monitoring program that will provide
the necessary data. The team should consider the following questions:
* Is there a general description of the CSS that includes the geographical area and
population served?
« Is there a map of the CSS depicting the location of all CSO outfalls and receiving
water bodies?
• Have sensitive areas and all outfalls located in these areas been identified?
* Is there a description of how the CSS responds hydraulically to rainfall events, and
is it adequate to determine which rainfall events trigger CSOs?
* Is there information on the volume, flow rate, and frequency of CSOs and the
pollutants discharged?
» Is there information on the CSO pollutant loadings and their impact*, on receiving
waters?
* Has all available information on pollutant loadings from cither r*"ini and nonpoint
sources in the watershed and their impacts on receiving watcr^ been identified and
compiled?
• Is there information on designated uses of receiving uatcrv and whether the
designated uses are being met?
« Does the CSS and CSO characterization provide informathm t»n the known effects of
the CSOs on water quality during precipitation events, as ud! a-> provide the level
of detail needed to model or project both the operation of the s> stem and the impacts
of various overflow scenarios on the receiving waters?
* Is monitoring sufficient to document baseline conditions to allow the permittee to
demonstrate the long-term benefits of CSO controls?
• Has the monitoring been coordinated with any ongoing or planned State programs and
programs of other permittees within the same watershed?
• If modeling was conducted, is the model identified and described, and are the results
provided?
Appendix B contains additional information on reviewing monitoring plans.
4-18 August 1995
SI,
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Chapter 4 ^ ^ Phase II PermMmg
4.5.1.3 CSO Control Alternatives
The pemit writer and the rest of the review team should consider cfae following questions
when reviewing the CSO control alternatives:
* Did the permittee develop a comprehensive list of CSO control alternatives? Did this
list include alternatives from each of the four general categories—source controls,
collection system controls, storage, and treatment technologies—described in guidance
for LTCPs (EPA, 1995a)?
* Did the permittee describe each CSO control alternative considered?
* Does the plan describe the process by which the CSO control alternatives were
developed?
* Does the plan compare the environmental benefits of the CSO control alternatives?
* Is cost/performance information (including curves) for each of the CSO control
alternatives provided? Do the cost/performance analyses evaluate a range of levels
of controls that were developed based on the permittee's site-specific conditions (e.g.,
zero overflow events per year, and averages of 1 to 3, 4 to 7, and 8 to 12 overflow
events per year)?
* Does the LTCP describe the approach used to screen the list of CSO control
alternatives, including the recommended screening criteria? Do the screening criteria
include performance factors, implementation and operation factors, such as costs, and
environmental impacts (described in EPA's guidance for LTCPs [EPA, 1995a])?
4.5.1.4 Selected CSO Controls
When evaluating the CSO controls, the permit writer should consider the following
questions:
» Is the presumption or demonstration approach used?
• Does the plan identify the reasons for selecting certain CSO controls and not others?
Were reasons for rejecting specific CSO control alternatives appropriate?
* Have the NMC been integrated into the permittee's description of its selected CSO
controls?
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Chapter 4 Phase II Permitting
« Will the selected CSO controls eliminate all CSOs to sensitive areas? If not, do the
data support the permittee's conclusion that elimination is not physically possible or
economically achievable?
* If CSOs to sensitive areas remain:
- Will these CSOs receive treatment?
- Will the CSO controls be sufficient to provide for the attainment of WQS?
* Have control efforts for other point and nonpoint sources of pollutants within the
watershed been considered?
* Will the CSO controls provide treatment or removal of floatables and settleable solids
equivalent to that achieved by primary clarification? Is the mechanism for solids and
floatables disposal described?
• Will the disinfection of effluent be necessary in order to attain WQS? If so, is
disinfection proposed as part of the CSO controls, and will removal of harmful
disinfection chemical residuals be necessary?
» Do the selected CSO controls provide the maximum pollution reduction benefits
reasonably attainable?
* Will the selected CSO controls provide for the attainment of WQS? If WQS cannot
be met because of sources other than CSOs, has the permittee provided information
on the other sources and natural background conditions?
* Has a total maximum daily load (TMDL) been developed for the watershed? If so,
has the permittee considered the TMDL in developing its LTCP?
* Are the selected CSO controls designed to allow cost-effective expansion or cost-
effective retrofitting if additional controls are determined necessary to provide for the
attainment of WQS?
4,5.1,5 Implementation Schedule
In reviewing the implementation schedule, the permit writer should use the data and
information supporting the prioritization of the CSO projects on the basis of their environmental
impacts, as well as the analysis of financial status, EPA's Combined Sewer Overflows-
Guidancefor Long-Term Control Plan (EPA. 1995a) and Combined Sewer Overflows—Guidance
for Financial Capability Assessment (EPA, 1995e) recommend criteria to evaluate the
reasonableness of construction schedules and financing plans in the LTCP. After reviewing
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Chapter 4 Phase II Permitting
these documents, the permit writer should refer to the following questions when reviewing the
implementation schedule:
* Do any phased construction schedules consider:
- Elimination of CSOs to sensitive areas
- Use impairment?
• Do any phased construction schedules include an analysis of financial capability, such
as the following factors:
- Median household income
- Total annual wastewater and CSO control costs per household as a percent of
median household income
- Overall net debt as a percent of full market property value
- Property tax revenues as a percent of full market property value
- Property tax collection rate
- Unemployment
- Bond rating?
• Did the permittee evaluate the following factors:
- Grant and loan availability
- Previous and current residential, commercial, and industrial sewer user fees and
rate structures
- Other viable funding mechanisms and sources of financing?
* Does the schedule include milestones for all major implementation activities,
including environmental reviews, siting of facilities, site acquisition, and Army Corps
of Engineers permitting?
The permit writer should review the financing plan to determine whether it provides the
funds necessary to construct CSO controls and assess whether water quality considerations merit
revisions to the proposed implementation schedule. If so, the permit writer may consider a
revised schedule.
4.5.1.6 Operational Plan
In evaluating the operational plan, the permit writer should consider whether me
permittee's O&M program addresses the evaluation criteria proposed in Section 4.4.1 for the
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Chapter 4 Phase II Permitting
NMC, However, the permit writer should ensure the operational plan includes newly-selected
CSO control structures,
4.5.1.7 . Post-Construction Compliance Monitoring
The permit writer should review the monitoring plan with members of the review team
who are knowledgeable about design and implementation of monitoring programs. When
evaluating post-construction compliance monitoring, the permit writer should consider the
following questions;
* Does the monitoring program include monitoring of CSOs that are representative of
the impacts to receiving waters?
* Does the monitoring program include ambient receiving water body monitoring at
representative CSOs, as well as monitoring prior to CSO impacts? Has the
monitoring program for the receiving water body been coordinated with any ongoing
or planned State programs and programs of other permittees within the same
watershed?
* Does the monitoring program include any biological parameters (e.g., fish,
zooplankton)?
* Does the monitoring program address pollutants included in the water quality criteria
for the specific designated use(s) of the receiving water, pollutants key to the
attainment of the designated use(s), and pollutants affected by the CSO controls?
• Does the monitoring program include appropriate measures of success?
Appendix B contains additional information on the review of a monitoring plan.
4.5.2 Implementation of the Long-Term Control Plan
As described in the CSO Control Policy, Phase I! permits should contain "narrative
requirements which ensure that the selected CSO controls are implemented, operated and
maintained as described in the long-term CSO control plan." Because the CSO controls will
have been selected on a site-specific basis, the implementation conditions should also be site-
specific. Thus, the permit writer should not simply develop a generic permit condition that
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Chapter 4 Phase II Permitting
requires implementation of the LTCP as developed, incorporating the LTCP into the NPDES
permit by reference. Rather, the permit should contain specific conditions that require
implementation of the selected CSO controls, the proposed O&M program requirements, and
the proposed post-construction compliance monitoring program. The following subsections
briefly discuss each of these portions of the LTCP.
4.5.2.1 Selected CSO Controls
The permit writer should develop permit conditions that specifically require the
implementation of the selected CSO controls, once approved. As discussed above, due to the
differences among CSSs, the CSO controls identified in LTCPs will vary from system to system.
In many cases, the CSO controls will require major construction and implementation activities
that can only be completed over several five-year NPDES permit cycles. The CSO Control
Policy recommends that the LTCP include the information necessary to develop the fixed-date
schedules for funding and implementing the CSO control program. The LTCP should prioritize
the individual projects within the overall control program on the basis of environmental impacts,
financial capability, and available funding. Section 3.5.1 provides additional discussions on the
permittee's development of implementation schedules.
When the implementation schedules for the selected CSO controls, are established, the
permit writer should determine the appropriate mechanism for imposing the schedule on the
permittee. As in the Phase I permit, the permit writer should require in the Phase n permit that
the permittee meet applicable WQS. If implementing regulations explicitly authorize a
compliance schedule, the permit writer may incorporate such a compliance schedule for the
attainment of water quality-based effluent limitations into the Phase II permit. In all other cases,
the Phase II permit must require immediate compliance with its technology- and water quality-
based requirements. When the permittee is unable to comply immediately with these
requirements (as will frequently be the case), the permit writer should include a fixed-date
implementation schedule in an enforceable mechanism issued simultaneously with the Phase n
permit. Appropriate enforceable mechanisms may include administrative or judicial orders. The
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Chapter 4 ^ Phase II Permitting
permit writer should discuss with the appropriate enforcement authority the choice of the
mechanism to use in each situation.
Exhibit 4-3 provides example language requiring compliance with an LTCP
implementation schedule for the selected CSO controls. The permit writer should evaluate this
language carefolly to ensure that it is appropriate for the permittee, (The example provided
assumes that the permittee has successfully implemented the NMC, and that the schedule is only
to implement the CSO controls identified in the LTCP.) In this permit requirement, the permit
writer should list specific activities necessary to implement selected controls. For example, if
one of the selected CSO controls is construction of a retention basin, the permit writer should
include specific language for the various activities necessary to complete the construction, as
shown in the italicized site-specific language in Exhibit 4-3. These activities and the
corresponding completion dates should be taken directly from the LTCP whenever possible. In
many instances, the LTCP might contain a combination of selected CSO controls, such as
construction of additional retention basins, separation of portions of the CSS, and maximization
of flow receiving primary treatment at the PQTW treatment plant. In these cases, the permit
writer should include activities with corresponding completion dates for implementing each of
the selected CSO controls. In addition to identifying compliance dates within the implementation
schedule, the permit writer should also require progress reports to demonstrate compliance with
the various compliance dates. Section 4.8 provides additional guidance on appropriate reporting
requirements for the Phase II permit.
4.5.2.2 Operational Plan
As described in Section 4.4.2, the permittee should have developed an O&M program
as part of the NMC. Once the permittee has selected CSO controls in its LTCP, the permittee
should revise the O&M plan developed and implemented as part of the NMC to include the
selected CSO controls. Example permit requirements for implementing the O&M program are
contained in Exhibit 4-2, given previously.
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Chapter 4 Phase II Permttmg
Exhibit 4-3, Example Permit Language for Implementing Selected CSO Controls
II. ' Long-Term Control Plan, . : •
~g% The permittee stall implemeat and" effectively operate and maintain the -CSO -conttols identiiecS i
":':"" long-term control plait HeimpteineBtalion'rfialaiefor ihese-comftpte shall be -as fellows:-
Activity '" , " -.
[insert name of adhityj - ' {tent1 date] :
1 Site-Specific Language: ••
1. JRetmtim 'basin '" .
• » Complete design of[neamuff retention basin.. • ' fmsert 4eteJ •
* Submit construstion. drawings for fmsmeif mmxtott basin,' flusett^fiatej
« -Initiate constructum @f foamed] retention. baste. ^jtmsert- intej
* C&aplste construction of fammMI maulm basin, ''- finMrtd@teJ- "
2. [Naned* separation ' ' - -
* Complete design, - ' Jteert JoteJ ,
* Solicit bids,' " . / " :; ' fioaort duiej "
cotttmcts* • ,
NOTE: 4 compliance schedule exceeding the ten of the permit may only be included 'in the permit if
autlioraed la the applicable Stele WQS, " ,^; ^/ />"' '' •
4.5.2.3 Post-Construction Compliance Monitoring
Implementation of the post-construction compliance monitoring program proposed by the
permittee as part of its LTCP generally is important for determining the overall effectiveness of
the selected CSO conttol(s) in achieving compliance with the CWA, It might not be appropriate
to require the implementation of a post-construction monitoring program until construction is
well underway or completed. Section 4.7 presents further guidance on Phase II permit
monitoring requirements,
4.5,2.4 Documentation for Fact Sheet/Statement of Basis
As discussed previously, the permit writer must prepare a fact sheet or statement of basis
that describes the basis for all NPDES permit conditions. For Phase H permits that require the
implementation of CSO controls selected in an LTCP, the permit writer should use the
information from the LTCP to record in the fact sheet or statement of basis the justification for
implementation of the specific CSO controls chosen by the permittee. In cases where the permit
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Chapter 4 Phase II Pemattiag
writer has determined that the permittee's proposed control levels and selected CSO controls are
not adequate to provide for the attainment of WQS, the permit writer should document the basis
for such determination (i.e., explain why the CSO controls selected by the permittee are not
adequate).
4.6 EFFLUENT LIMITATIONS
As with the Phase I permit and consistent with 40 CFR 122.44 (NPDES requirements),
both technology- and water quality-based effluent limitations are included in the Phase n permit.
However, these two permit phases differ with respect to the type of effluent limitation each
permit phase should require. The CSO Control Policy provides that in Phase I, the permit
writer should establish narrative water quality-based effluent limitations; by comparison, the
CSO Control Policy recommends that Phase n water quality-based effluent limitations be
expressed as numeric performance standards (e.g., number of overflow events per year) for the
selected CSO controls. Wnen sufficient CSO-related information and data are available for the
permit writer to develop numeric water quality-based effluent limitations, the permit writer
should do so. This information, however, is not likely to be available for inclusion in the
Phase II permit.
4.6.1 Technology-Based Requirements
Phase n permits should require CSO permittees to continue implementation of
technology-based controls. These technology-based controls generally include the NMC on a
BPJ basis and may also include components of any additional technology-based controls selected
in the LTCP. The permit writer should re-evaluate and incorporate appropriate NMC
requirements in the Phase n permit, as discussed in Section 4.4, The discussion of the
technology-based requirements presented in Section 3.6.1 is also applicable to Phase n permits.
4.6.2 Water Quality-Based Requirements
In developing water quality-based requirements for CSOs, the permit writer should have
a thorough understanding of the applicable State WQS and any specific guidance related to wet
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Chapter 4 Pitase If Permitting
weather conditions. This information, in addition to the LTCP information, will provide the
basis for the permit writer to develop the appropriate water quality-based requirements in the
Phase II permit.
As described in Section IV.B.2 of the CSO Control Policy, Phase II permits should
contain "Water quality-based effluent limits under 40 CFR 122.44(d)(l) and 122,44(k),
requiring, at a minimum, compliance with, no later than the date allowed under the State's
WQS, the numeric performance standards for the selected CSO controls...." The CSO Control
Policy assumes thai adequate data will generally not be available at the beginning of the Phase
n permitting process for the permit writer to fully and accurately assess the need for numeric
water quality -based effluent limits. Consequently, the CSO Control Policy depends on
compliance with the performance standards of the selected CSO controls to a.hic%c water quality
goals.
The performance standards to be applied to a permittee will dc-pcnJ > >r the selected CSO
control approach. The CSO Control Policy specifies the perform-iiva- vtarwiards for the
presumption approach. To satisfy the demonstration approach, the permit u nti-r vhould establish
performance standards for the selected CSO controls that will prtnuk » •: the attainment of
WQS. The following subsections discuss the water quality-related v-rMJcrjiums for each
approach.
In addition to performance standards designed to meet WQS. ihc permit writer should
include narrative permit language providing for the attainment of applicable WQS. In certain
circumstances, sufficient data may exist (e.g., the permittee may have substantially completed
construction of selected CSO controls) for the permit writer to develop numeric water quality-
based effluent limits. EPA's Technical Support Document for Water Quality-based Toxics
Control (EPA, 1991) might provide useful insights on determining appropriate water quality-
based effluent limitations. Although this EPA manual is intended to address continuous
discharges, it may provide useful information for wet weather flows.
4-27 August 1995
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Chapter 4 Phase II Permitting
4.6,2,1 Presumption Approach
Where a permittee chooses (and the NPDES permitting authority authorizes) the
presumption approach, he or she will likely be required to meet numeric performance standards
(e.g., a certain number of overflow events per year). These criteria were established in the CSO
Control Policy because "data and modeling of wet weather events often do not give a clear
picture of the level of CSO controls necessary to protect WQS," The CSO Control Policy
presumes, therefore, that compliance with these numeric performance standards generally will
be sufficient to meet WQS. The permit writer will be responsible, however, for ensuring that
this presumption is reasonable for the CSOs to be permitted. To determine whether the
presumption approach is reasonable, the permit writer should review the data generated and
analysis conducted to characterize, monitor, and model the CSS and to review the consideration
of sensitive areas by the permittee,
Exhibit 4-4 provides example permit language for a permittee that uses the presumption
approach. The permit writer should evaluate this language carefully to ensure that it is
appropriate for the permittee. (The example permit language addressing disinfection
requirements specifically requires reduction of a pathogen indicator (e.g., E. coli) to levels that
will provide for attainment of WQS. This example language assumes that such a standard exists.
In addition, the example permit language assumes that the control of harmful disinfection
products (e.g., chlorine) might be necessary. In both cases, the permit writer should customize
the disinfection requirements to those required to meet State WQS.)
The permit writer will be responsible for eventually reviewing the permittee's evaluation
of CSO controls and determining whether water quality will be adequately protected. It is likely
that an adequate demonstration and review for attainment of WQS will not be possible until the
permittee has implemented its selected CSO controls. Therefore, the permit writer might not
complete an evaluation, including consideration of the development of numeric water quality-
based effluent limitations, until the post-Phase H CSO permitting. In any case, use of the
presumption approach does not shield a permittee from the possibility that additional controls
might eventually be necessary in order to attain water quality objectives.
4-28 August 1995
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Chapter 4
Phase II Permitting
Exhibit 4-4. Example Permit Language for Performance Standards for the
Presumption Approach
llie ::pennitt€e ;shali ;coiBply with ;C!
t!ie;faH0wiBg;perfoimaa^
|6|j|iitt
shall eliminate or :captoie fer :tteaimenl,
pn^l^j^
^ requawamES ::as
cttraitSvSfeai! feevnla
4.6.2.2 Demonstration Approach
Under the demonstration approach, the permittee should be required to show that the
selected CSO controls will not cause or contribute to the exceedance of WQS. In a receiving
water with pollution sources other than the permittee's CSOs, this may be accomplished through
the watershed approach. The permit writer will be responsible for ensuring that the permittee
demonstrates that the selected CSO controls are adequate to provide for the attainment of WQS.
The specific performance standards that should be included in a permit will depend on the CSO
4-29
August 1995
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Chapter 4 Phase II Permitting
controls selected. This manual does not provide example permit language for the demonstration
approach because such language will be site-specific and based on the permittee's demonstration.
However, the permit writer should attempt to draft permit language in terms of performance
standards or other clear specific standards similar in type to the examples provided in
Exhibit 4-4 for the presumption approach. Not all selected CSO controls (e.g., extensive use
of BMPs) lend themselves to specific numeric performance standards. However, the permit
writer should still attempt to develop permit conditions that will hold die permittee accountable
for implementing CSO controls as planned (e.g., specifying implementation and scheduled
evaluation of BMPs).
4.7 M0NITOEING
Monitoring is generally necessary to 1) evaluate the water quality tmp-uts from CSOs on
receiving waters and the effectiveness of CSO controls and 2) determine compliance with permit
conditions and ultimately the attainment of WQS. The first type of rn.'nu.Tinp should be
conducted during the Phase n permit term and should be sufficient IP e%alujic water quality
impacts of CSOs on the receiving water bodies and to evaluate the effects L-HOA »>! CSO controls
during the construction/implementation period. The latter type t»S ni.»nu.»nnj! should be
conducted after construction of selected CSO controls has been completed anJ sh.
-------
Chapter 4 Phase H PermMng
Permit monitoring conditions should be clear and concise, maintaining flexibility to
account for site-specific factors. Where possible, to ensure that the conditions are enforceable,
the permit writer should develop permit conditions that incorporate specific elements of the
submitted plan rather than general requirements. The permit writer may copy specific portions
of the proposed plans into the permit.
Exhibit 4-5 presents an example of site-specific permit language. (The pollutants listed
in Exhibit 4-5 are included as an example only and are not intended as a mandatory list of
required monitoring parameters. Permit language and the list of pollutants to be monitored
should be developed to reflect the permittee's site-specific characteristics.) In addition, the
permit writer should require the permittee to monitor appropriate measures of success, developed
as part of the LTCP.
EPA cautions the permit writer against requiring implementation of the monitoring plan
by reference. This approach might be more difficult to enforce because of the possible
ambiguity of such language.
If CSOs are causing substantial water quality impacts, the permit writer may want to
require special characterization studies, including the following:
* Sediment studies
* Whole effluent toxicity testing
* Biological assessments.
This type of monitoring, generally a short-term study, can be required as a special
condition. Typically, such a study is required in response to specific information indicating that
water quality is being affected. The permit writer may want to develop permit conditions that
require: 1) a separate monitoring plan to be developed for each special study, 2) the plan be
submitted for review prior to performing the monitoring, and 3) the submission of a final report
to the permitting authority within a specified time after study completion.
4-31 August 1995
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Chapter 4
Phase II Permitting
4-5, Permit for Site-Specific
Siu-Sjpeqjic Langmg e: : , ; '; . .; -:"
The permittee- shall monitor CSOs meL report remits to the permitting authority ia-aocordaace-"w^h the
.foll&wlag': -. -. '• . •
Clwracteristle •
Repotting
Code
•;•
LTarB
.
Ptewa^tt*
AfflHttwia -•",-. '
= Ammonia
:BODS t:;<
BODS' ••
PSic^lerus
Total iSo^ndol
•
ToM Suspended
Solids -
Fecal .CoMontt
; Monitoring ReqtttreaieBls . '
Measuremefit ..- , -*.
Freqweiicj'
' ..-;. •:
£
Sample Type
a*- :
Comiwite . -••'
C^raft)-" "
CM^OMte ;
C«ni«i^te
. . .-. .-
CoEt^osiie
G**'': •.•"''-," '^
L The grab statple sfwtt btt_ ceflecfaf mtMn ffmert. sfptwpriate-miimt&J ^••fhe-diseiafge at the
.. fylhwing (^O auifalls linsert afpT&prio£e Mentificoti&nJ. The grab sample shali be collecl-ed fms&t ' '
typmpnette aamteij times-per year* '•• . ' ' ' . ' ''-•''"
2. The coaym$lt£ skatt fre from the staff -affib^ 'i!isiA®Fg€ umil if wift , the
period mffi to 24 ftsars at the fattening Gl® otajalls j^eit^appmpfiate, MufttftcsSionj. 21e " .
composite sample, shall be collected flasett ,8fpmprtate number] Ames. per year, lins&i appmpnale
snwft«f during the, feriod. from Mo$ - October ofyi\ptu>eft' ttpjmjiriiiif mwimber] "during -the
period fi-0m November ~ ApriL The permittee- sftsff sabwf--fhjt remits no later i&m Mevembfp Jftffr»rf
May 3Ist, respective^* : vs'bjc^ ,
,. '" . :?"* : "': ' '"'
*I^raraeters listed in tMs exhibit are e?carapl« oaiy. The list of parameters to raesillor mw& be
developed ea a stle^pecifie basis, . ,:
The permit writer should review the monitoring plans carefully to verify that the design
ensures that CSO information is correlated with water quality impacts; otherwise, the results of
the studies might not provide conclusive evidence of the cause of impact, In addition, other
studies might be needed in conjunction with these special studies. For example, sediment studies
might not be meaningful without a contaminant transport modeling study, and a bioassay
performed without toxicity data and CSO data might not provide meaningful results.
4-32
August 1995
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Chapter 4 Phase H Permitting
For additional information on these types of testing, the permit writer is referred to the
Combined Sewer Overflows—Guidance for Monitoring and Modeling (EPA, 1995d).
4.8 REPORTING
Four types of reporting requirements relating to CSO controls should be included in the
Phase B permit: 1) re-evaluations associated with and reports/recordkeeping to document
continued implementation of the NMC, 2) progress reports associated with implementation of
long-term CSO controls, 3) monitoring data, and 4) other pertinent information (e.g., sensitive
area reassessment):
« NMC Implementation—Examples of recordkeeping requirements associated with the
ongoing implementation of the NMC have been incorporated into the example permit
language associated with NMC implementation (see Section 4.3.2). The permit
writer may choose to require reporting of any of this information. In addition, if the
permit writer chooses to require any re-evaluations associated with any of the
minimum controls, such as a reassessment of the pretreatment program or additional
revisions to the municipal ordinance, the permit writer may require reporting of these
re-evaluations.
* LTCP Implementation - Progress Reports—Because the implementation of the
LTCP may be phased, the permit writer may require progress reports associated with
the implementation of CSO controls. Exhibit 4-6 presents example permit language
for requiring the submission of progress reports.
Exhibit 4-6. Example Permit Language for Requiring Submission of Progress Reports
Within 14 days of-each completion date specified in [Insert appropriate section] of this permit^ the
permittee shall submit a written progress report to the permitting authority stating whether or aot the
particular activity was completed. If the activity was not completed, the report shall also include (1) an
explanation of the faiiaxe to accomplish the. activity, (2) actions taken by the permittee to correct the
situation,, and (3) an estimate of when the activity will be completed.
Monitoring Data—Monitoring data collected during Phase n should be submitted to
the NPDES permitting authority on a scheduled basis. Exhibit 4-5 provides example
permit language that includes reporting requirements for Phase II monitoring.
Other Information—The permit writer should consider other applicable reporting
requirements. Depending on whether the permittee has chosen to implement the
presumption or the demonstration approach, for example, it might be appropriate to
require the permittee to report the number of overflow events or document other
4.33 - August 1995
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Chapter 4 Phase II Permitting
controls selected. This manual does not provide example permit language for the demonstration
approach because such language will be site-specific and based on the permittee's demonstration.
However, the permit writer should attempt to draft permit language in terms of performance
standards or other clear specific standards similar in type to the examples provided in
Exhibit 4-4 for the presumption approach. Not all selected CSO controls (e.g., extensive use
of BMPs) lend themselves to specific numeric performance standards. However, the permit
writer should still attempt to develop permit conditions that will hold die permittee accountable
for implementing CSO controls as planned (e.g., specifying implementation and scheduled
evaluation of BMPs).
4.7 M0NITOEING
Monitoring is generally necessary to 1) evaluate the water quality tmp-uts from CSOs on
receiving waters and the effectiveness of CSO controls and 2) determine compliance with permit
conditions and ultimately the attainment of WQS. The first type of rn.'nu.Tinp should be
conducted during the Phase n permit term and should be sufficient IP e%alujic water quality
impacts of CSOs on the receiving water bodies and to evaluate the effects L-HOA »>! CSO controls
during the construction/implementation period. The latter type t»S ni.»nu.»nnj! should be
conducted after construction of selected CSO controls has been completed anJ sh.
-------
Chapter 4 Phase H PermMng
Permit monitoring conditions should be clear and concise, maintaining flexibility to
account for site-specific factors. Where possible, to ensure that the conditions are enforceable.
the permit writer should develop permit conditions that incorporate specific elements of the
submitted plan rather than general requirements. The permit writer may copy specific portions
of the proposed plans into the permit.
Exhibit 4-5 presents an example of site-specific permit language. (The pollutants listed
in Exhibit 4-5 are included as an example only and are not intended as a mandatory list of
required monitoring parameters. Permit language and the list of pollutants to be monitored
should be developed to reflect the permittee's site-specific characteristics.) In addition, the
permit writer should require the permittee to monitor appropriate measures of success, developed
as part of the LTCP.
EPA cautions the permit writer against requiring implementation of the monitoring plan
by reference. This approach might be more difficult to enforce because of the possible
ambiguity of such language.
If CSOs are causing substantial water quality impacts, the permit writer may want to
require special characterization studies, including the following:
* Sediment studies
* Whole effluent toxicity testing
* Biological assessments.
This type of monitoring, generally a short-term study, can be required as a special
condition. Typically, such a study is required in response to specific information indicating that
water quality is being affected. The permit writer may want to develop permit conditions that
require; 1) a separate monitoring plan to be developed for each special study, 2) the plan be
submitted for review prior to performing the monitoring, and 3) the submission of a final report
to the permitting authority within a specified time after study completion.
4-31 August 1995
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Chapter 4
Phase II Permitting
4-5. Permit tor Site-Specific Monitoring ActifMes
Site-^tedfic Lang wag e; :• • ~ ~" ,.; •'•"
He penmttee shall 'monitor CSOs artel report results to the peimttmg authority in -accordance "»f A fte _
jbltotoiifc:-- :..'". • • -.-;•'
CbaisiEterisfle •
Repertiig,
Code-
'
,;•;-
JPtoamrtaf1'
• j&nsinoiiiii
•Anuuoniii
:BODS- t:?;:
BODS; ,
Total ;SoqwttiM
-'Solids'
Total. Suspended
Solids-
Feoi-CtoMfoiin
•- • Monitoring EeqtKreineafs • , .• :
Measjiremeat ,,- . -,:
fz^paMgr
'.,;-.
SasspteType
Grab :
Conqwite , , -
<3iab-; '
CoaaRoste
CoD^a^te;.
Giab /_ .-..-
€onp»»1; '
Gnfc.- .-:•"•" "
1, 'The grab smtpte shall- be_ c@lle£tei within ffmsert. ^ffofrieae<:sm^&] •ofzke af 'fAe
. follmmg^ CSO jteert,-i^f««piiafeM«^«aS0ii|. He ••gmb''simylff:.skalt ifte ffjimft ' ' °
ajpnjpriate nmd^, times per yiiar* '• • . ••_•'. '•••'•''
5. The - skai. be from rfte $mt -of :ite «tfi"I ir • waft . file _
pm®$ -mt'to -exceed 24 hours at the foUftMttg &O 0taf@n$ jpsert -.ajitmjmate Metttijfata&mJ. Jibe.
composite shall be -liiKett.-ttgpMprisie maaimj times. per yew,. ff®s&t-afipi9pri(ia®
IUM&&J during the. period fivm May - 0&ober and^ltaserf @ppmprieite mv^erj tim&:^nng the
period fi"0m Nammisier - Aprti. UK perm&tee-. sitofi' m%mif-:ifae'rgMt$"k& to^r than Jfowraifrgr. Jftfr-fi»l
Afoy JI«, repeetivety, ' ' • ^---^ _ '. . ' '
- ." ?;> • ' -- - - •--
*Pararaeters listed In tMs exhibit are examples cmlf . The list of parameters to matte* misst. be
dwdojprf ««astte»sp^fic:-basis» . ;• "",.:„
The permit writer should review the monitoring plans carefully to verify that the design
ensures that CSO information is correlated with water quality impacts; otherwise, the results of
the studies might not provide conclusive evidence of the cause of impact, In addition, other
studies might be needed in conjunction with these special studies. For example, sediment studies
might not be meaningful without a contaminant transport modeling study, and a bioassay
performed without toxicity data and CSO data might not provide meaningful results.
4-32
August 1995
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Chapter 4 Phase H Permitting
For additional information on these types of testing, the permit writer is referred to the
Combined Sewer Overflows—Guidance for Monitoring and Modeling (EPA, 1995d).
4.8 REPORTING
Four types of reporting requirements relating to CSO controls should be included in the
Phase B permit: 1) re-evaluations associated with and reports/recordkeeping to document
continued implementation of the NMC, 2) progress reports associated with implementation of
long-term CSO controls, 3) monitoring data, and 4) other pertinent information (e.g., sensitive
area reassessment):
« NMC Implementation—Examples of recordkeeping requirements associated with the
ongoing implementation of the NMC have been incorporated into the example permit
language associated with NMC implementation (see Section 4.3.2). The permit
writer may choose to require reporting of any of this information. In addition, if the
permit writer chooses to require any re-evaluations associated with any of the
minimum controls, such as a reassessment of the pretreatment program or additional
revisions to the municipal ordinance, the permit writer may require reporting of these
re-evaluations.
* LTCP Implementation - Progress Reports—Because the implementation of the
LTCP may be phased, the permit writer may require progress reports associated with
the implementation of CSO controls. Exhibit 4-6 presents example permit language
for requiring the submission of progress reports.
Exhibit 4-6. Example Permit Language for Requiring Submission of Progress Reports
Within 14 days of-each completion date specified in [Insert appropriate section] of this permit^ the
permittee shall submit a written progress report to the permitting authority stating whether or aot the
particular activity was completed. If the activity was not completed, the report shall also include (1) an
explanation of the faiiaxe to accomplish the. activity, (2) actions taken by the permittee to correct the
situation,, and (3) an estimate of when the activity will be completed.
Monitoring Data—Monitoring data collected during Phase n should be submitted to
the NPDES permitting authority on a scheduled basis. Exhibit 4-5 provides example
permit language that includes reporting requirements for Phase II monitoring.
Other Information—The permit writer should consider other applicable reporting
requirements. Depending on whether the permittee has chosen to implement the
presumption or the demonstration approach, for example, it might be appropriate to
require the permittee to report the number of overflow events or document other
4.33 - August 1995
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Chapter 4 Phase II Permitting
performance standards. The permit writer may also require the permittee to provide
"measures of success" data not otherwise reported as part of the monitoring data.
Such data might include a reduction in the number of overflow events, reduction in
number of CSO outfalls, volume of untreated/treated CSOs, or other improvements
in receiving water quality. Section 2.9 discusses the different types of measures of
success for the CSO program. In addition, any reassessments recommended by the
CSO Control Policy, such as the reassessment of CSOs to sensitive areas, should also
be submitted to the NPDES permitting authority. Section 4.9.2 discusses special
conditions regarding sensitive areas.
4.9 SPECIAL CONDITIONS
This section discusses three special conditions: 1) CSO-related bypasses, 2) sensitive
area reassessment, and 3) reopener clauses. The sensitive area reassessment special condition
should appear hi any CSO permit where a CSO occurs to a sensitive area and the permittee is
not planning to eliminate or relocate the CSO outfalls from that area during the permit term.
The reopener clause should appear in all Phase II permits.
4.9.1 CSO-Related Bypass
Some POTW treatment plants might have significant primary treatment capacity in excess
of their secondary treatment capacity. During development of the LTCP, a community might
want to consider using this excess primary treatment capacity as one CSO control alternative,
which may be used in conjunction with other CSO control alternatives to ensure compliance with
CWA requirements. The CSO Control Policy outlines a process for "CSO-related bypass"
whereby, under certain circumstances, the permit writer may allow wet weather flows to receive
primary clarification at the POTW treatment plant and then be discharged, without these flows
being subject to secondary treatment requirements.
"Bypass." the intentional diversion of waste streams from any portion of a treatment
facility, is prohibited by NPDES regulations unless the requirements of 40 CFR 122.4l(m) are
met. Under the regulations, to take advantage of the bypass provisions, the permittee must show
that the bypass was unavoidable to prevent loss of life, personal injury, or severe property
damage, that there was no feasible alternative to the bypass, and that the permittee submitted the
4.34 August 1995
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Chapter 4 Phase M PermMmg
required notices, After considering "its adverse effects," the NPDES permitting authority may
approve an anticipated bypass if the permittee has met these three conditions.
The permittee is normally responsible for documenting compliance with 40 CFR
122.41(m) on a case-by-case basis. In the CSO Control Policy, EPA interpreted these
regulations to allow authorization, by permit condition, of a CSO-related bypass of the secondary
treatment portion of the POTW treatment plant in specific limited circumstances. For permittees
with excess primary capacity at the POTW treatment plant, the permit writer may consider
including a CSO-related bypass provision in the permit. When considering whether such a
condition is appropriate, the permit writer should consult the information and justification for
the bypass submitted in the permittee's LTCP. In addition to presenting information in the
LTCP documenting compliance with the baseline requirements of 40 CFR 122.41(m), the CSO
Control Policy states that, at a minimum, the LTCP "should provide justification for the cut-off
point at which the flow will be diverted from the secondary treatment portion of the treatment
plant, and provide a benefit-cost analysis demonstrating that conveyance of wet weather flow to
the POTW for primary treatment is more beneficial than other CSO abatement alternatives such
as storage and pump back for secondary treatment, sewer separation, or satellite treatment,"
For purposes of applying the bypass regulation to CSOs, "severe property damage" could
include situations where flows above a certain level could wash out the POTW's secondary
treatment system. The "no feasible alternative" requirement of the regulation can be met if the
record demonstrates that the secondary treatment system is properly operated and maintained,
that the system has been designed to meet secondary limits for flows greater than the peak dry
weather flow plus an appropriate quantity of wet weather flow, and that it is either technically
or financially infeasible to provide secondary treatment for greater amounts of wet weather flow.
This analysis should include, for example, consideration of enhanced primary treatment and non-
biological secondary treatment, as well as additional construction to increase plant capacity. The
NPDES permitting authority may grant interim authorization to bypass that results from wet
weather flows, which, in the absence of implementation of the nine minimum controls, would
be untreated from a CSO without consideration of the feasibility of additional construction.
4-35 August 1995
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Chapter 4 Phase II Permitting
Where such interim authorization is granted, however, the permit must specify that the permittee
is required, as part of its LTCP, to implement all feasible alternatives to bypass, including
additional construction at the facility or other controls within the collection system. Other bases
supporting a finding of no feasible alternative might also be available on a case-by-case basis.
As part of the consideration of possible adverse effects resulting from the bypass, the permit
writer must determine that the bypass will not cause exceedances of WQS.
Based on the technical justification developed and submitted by the permittee, the permit
writer should include in the permit the conditions under which a CSO-related bypass would be
authorized, as well as specify any required treatment, monitoring, or effluent limitations related
to the bypass event. The permit writer should also include requirements for appropriate
notification of the CSO-related bypass to the NPDES permitting authority. The CSO Control
Policy recommends that the permit require all wet weather flows passing the headworks of the
PQTW treatment plant to receive at least primary clarification, solids and floatables removal and
disposal, disinfection (where necessary), and any other treatment that can reasonably be
provided. The permit writer may specify monitoring requirements to determine whether a
substantial increase in the volume or character of pollutants introduced to the POTW occurs.
If the POTW is required to disinfect bypassed flows, and if chlorine is used to disinfect, the
permit writer may apply effluent limitations for total residual chlorine to ensure protection of
receiving water quality and attainment of WQS.
As stated previously, the CSO Control Policy recommends that the LTCP provide
adequate justification for the CSO-related bypass and clearly define the wet weather flow
conditions and flow rate at which secondary treatment capacity is exceeded. In addition, the
CSO Control Policy recommends that the permittee demonstrate that conveying combined
sewage to the POTW treatment plant for primary treatment is more beneficial than other options,
based on a cost/performance analysis. The permit writer should use this information to draft
a site-specific CSO-related bypass provision that specifies the flow rate at which the CSO-related
bypass will be allowed; any appropriate treatment, monitoring, or effluent limitations; or other
CSO-related bypass requirements. The permit language should indicate that bypasses that occur
4-36 August 1995
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Chapter 4 Phase II PermMmg
when the flow at the time of the bypass is under the specified flow rate are not authorized by
the CSO-related bypass condition. The permit writer should compile sufficient data and
information in the administrative record and in the permit fact sheet or statement of basis
supporting all the requirements in 40 CFR 122,41(m)(4) for approval of an anticipated bypass.
Exhibit 4-7 presents an example of permit language for a CSO-related bypass. The permit
writer should evaluate this language carefully to ensure that is appropriate for the permittee,
Exhibit 4-7. Example Permit Language for a CSO-Related Bypass
A CSO-related bypass of the secondary treatment portion of the POTW treatment plant is authorized when
the flow rate to the POTW treatment plant as a result of a precipitation event exceeds [insert flow rate in
MGD). Bypasses thai occur when the flow at the time of the bypass is under the specified flow rate are not
authorized under this condition and are subject to the bypass provision at 40 CFR I22.41(oi}« In the event
of a CSO-retated bypass authorized under this condition, the permittee shall minimize the discharge of
pollutants to the environment. At-a minimum.* CSO-related bypass flows must receive primary clarification,
solids-.and floatables removal, and disinfection. The permittee shall report any substantial changes urine
volume.or character of pollutants being introduced into the POTW. Authorization of CSO-related bypasses
under this provision may be modified or terminated when there is a substantial change in the volume or
character of pollutants being introduced to the POTW, The permittee shall provide notice 10 the permitting
authority of bypasses authorized under this provision with 24 hours of occurrence of the bypass.
4.9.2 Reassessment of Sensitive Areas
Under the CSO Control Policy, the permittee's LTCP should give the highest priority to
controlling CSOs to sensitive areas, as defined by the NPDES permitting authority. The goal
for controlling CSOs to these areas is to eliminate the CSOs or relocate them whenever it is
physically possible and economically achievable. If it is not possible, then the permittee should
be required to treat the CSOs that are not eliminated or relocated to the degree necessary to
provide for the attainment of WQS,
For CSOs to sensitive areas that were not eliminated or relocated, the permit writer
should include in the initial Phase II permit, and in subsequent permits, a special condition
requiring the permittee to reassess the feasibility of doing so. The permit writer should require
the permittee to develop and submit a report on this reassessment. The permit writer should
require the permittee to evaluate the availability of new technologies that might be useful in
eliminating or relocating these CSOs and any changes in the permittee's economic situation that
4,37 August 1995
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Chapter 4 Phase II PermMng
would enable the permittee to fund the required projects for eliminating or relocating the CSOs
from sensitive areas. Exhibit 4-8 provides example permit language for reassessment of
sensitive areas for use in Phase II and subsequent permits. The permit writer should evaluate
this language carefully to ensure that it is appropriate for the permittee.
Exhibit 4-8. Example Permit Languap for Sensitive Area Reassessment
[This permit condition is only appropriate for CSSs with CSOs to sensitive areas that have not been
eMmtaated or relocated.]
The pemittee shall reassess the feasibility of eliminating or relocating CSO outfalls [insert outfall
identification numbers for CSOs to sensitive areas] discharging to [insert name of receiving water body
or bodies corresponding to each outfall identified]/- The permittee shall consider new or improved
techniques to eliminate or relocate overflows or changed circumstances that influence economic achievability,
• The peitnittee shall prepare and submit to the petinitting authority a report that presents -the results of ffiis
reassessment, including the pertnittee's recommendations regarding, the elimination or relocation of these
outfalls. The pomittee shall submit such report no later than [insert date].
4.9.3 Permit Reopener Clause
As with any NPDES permit, the Phase II permit should include a reopener clause that
authorizes the NPDES permitting authority to modify or revoke and reissue the Phase I! permit
for cause, Such cause could include a determination that the selected CSO controls fail to
provide for the attainment of WQS or WQS are revised to address wet weather conditions on
the basis of a use attainability analysis.
Modifying the Phase II permit will require the modification of any enforcement
mechanism issued with the Phase II permit to maintain consistency with the modified or reissued
Phase II permit. For this reason, the permit writer should coordinate with the appropriate
NPDES enforcement authority when a Phase II permit is reopened.
Before exercising any reopener provision, the permit writer should consider the timing
of the scheduled permit reissuance. If it is late in the five-year permit cycle, the permit writer
may want to address the changes in the context of the normal permit reissuance process. The
4-3 g August 1995
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Chapter 4 Phase II Permitting
NPDES permitting authority might have standard procedures that govern the use of reopener
clauses, and the permit writer should follow these procedures when appropriate.
It is possible that a generic reopener clause used in other NPDES permits is sufficiently
broad to address CSOs. Alternatively, the permit writer may revise the generic reopener clause
to specifically include the CSO-related causes for which the Phase fl permit may be reopened,
or the permit writer may include a separate reopener clause that only identifies the CSO-related
causes for which the Phase II permit may be reopened. Exhibit 4-9 presents example language
for the latter case. The permit writer should evaluate this language carefully to ensure that it
is appropriate for the permittee, EPA's Training Manual for NPDES Permit Writers presents
additional information on the use of standard reopener clauses in NPDES permits (EPA, 1993).
4-9. Example for Rtopeier
may -be modified orrcvokedi aad xefesoed, as proviled-jmsuaatw 40 CFR 122,62' afl -124.5,
for Ae following reasons;, K- : : ' . ''.!••"• . •,•'•" t - '.
-,, * To iac&de new or revised conditions developed to .eoinply. wittt any or. Federal law or.
_ /•• regulation thai addresses. CSOs that is adopted' or pBbn^gate&subseqpent to ttr effective- '
:"-K date of this permit '-, ; ' , ' -:' "• ":"
« To iaetefe new or revised conditions if aew iofonoaiion, mt a^aiatte at the lime-
: • issoaiKe, ipdicates tot CSOr-coottols impost unier the perMt.have to
of State WQS$, = , - '' •$% • .....'"•'•' ' .
•= i- * To iuclade new or itvised conditions based on nwlofonnattea 'from impleiwarticm of
the loog-tenii-control
tMs permit -may be modified or revoked and reissued Ibr'aay reason specified- in
40 X3F1 122.62. -,' : . ./:' . ' • ;" • '
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CHAPTERS
POST-PHASE n PERMITTINiG
5.1 CONTINUATION OF PHASE II
The permit writer's responsibilities continue even after issuance of the first Phase n
permit requiring implementation of the selected combined sewer overflow (CSO) controls from
the long-term control plan (LTCP). Phase II, in many cases, may extend through numerous
five-year National Pollutant Discharge Elimination System (NPDES) permit cycles. The number
of cycles will depend on the length of time necessary to complete construction of the selected
CSO controls. In cases where construction will take more than five years, the permit writer
should coordinate with the NPDES enforcement authority to ensure thai a compliance schedule
for implementation of CSO controls is contained in an appropriate enforceable mechanism.
The permit writer should continue to include in subsequent Phase II permits any
conditions that require the permittee to implement the selected CSO o'nirols. continue
implementation of the nine minimum controls and require reassessment of o\crtl »*\ to sensitive
areas. The requirement to implement the post-construction compliance ni »n:i Ting program
should be included in a Phase H permit to evaluate water quality impad- ?r.>n> CSOs and the
effectiveness of CSO controls (in cases where some of the selected CSO «..>n:rolv have been
completed) and in the first post-Phase II permit to determine compliance u nf permit conditions
and ultimately the attainment of WQS. Chapter 4 provides specific mfornijn.»n on these Phase
II permit conditions.
In addition, the permit writer should continue to work closely with the permittee during
these subsequent permit cycles. The permit writer should continue to require the permittee to
periodically report the status of implementation of the selected CSO controls (see Section 4.8).
Continued involvement by the permit writer is critical to the development of the NPDES permit
following implementation of the selected CSO controls.
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Chapter 5 Post^Phme II Permitting
5.2 SUBSEQUENT CSO PERMITTING
Prior to issuing the NPDES permit for the period in which the permittee's implementation
of selected CSO controls is expected to be completed, (he permit writer should reach an
agreement with the permittee on the implementation of a post-construction compliance
monitoring program (prepared during development of the LTCP) that will generate information
and data necessary to determine whether the selected CSO controls are achieving compliance
with applicable State water quality standards (WQS). The permit writer should generally
incorporate the requirement to conduct this post-construction monitoring program into the first
NPDES permit issued following completed construction of the selected CSO controls.
Additionally, when enough water quality data have been generated, the permit writer should use
the data to develop numeric water quality-based effluent limits as appropriate for inclusion in
subsequent NPDES permits.
When using the data and information generated by the permittee under the Phase II
pemit(s) to develop numeric water quality-based effluent limits, the permit writer should
consider the following questions:
« Were CSO frequency, duration, and volumes estimated or measured?
» Were all pollutants of concern identified, including toxics, and were overflow
concentrations/loadings for each pollutant estimated or measured?
* Did the permittee identify and monitor for pollutants addressed by applicable State
water quality criteria?
* Did the permittee obtain data on ambient background concentrations of pollutants of
concern?
* Were appropriate flow values for receiving water bodies used? State WQS may
specify the flows under which water quality criteria must be achieved.
» If applicable, were mixing zones calculated in accordance with State standards or
policies?
* Was the cumulative impact of multiple CSOs to the same receiving water body
considered?
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Chapter 5 Post-Phase B Permitting
* Were other point and nonpoint sources of pollutants within the same watershed
considered?
* Was the model used suitable for wet weather episodic discharges?
* Were antecedent conditions appropriately used in setting up the model?
* Was information obtained on the most sensitive and most affected areas (e.g.,
shellfish propagation, drinjdng water supply)?
The permit writer might need additional information and data depending on the policies
and procedures used by the NPDES permitting authority to evaluate water quality impacts and
develop numeric water quality-based effluent limits. The scientific/technical issues affecting
determination of the need for water quality-based effluent limits for CSOs might be different
from those commonly used by permit writers for continuous wastewater discharges from other
point source categories. For example, use of chronic criteria designed for a particular low flow
scenario might not apply during wet weather flow conditions when CSOs are likely to occur.
In addition, State WQS might have been revised to better reflect receiving water body uses
during wet weather conditions.
Therefore, the U.S. Bavironmental Protection Agency recommends that the permit writer
involve appropriate WQS authorities in evaluating whether CSOs will achieve WQS and
developing numeric water quality-based effluent limits. The Technical Support Document far
Water Quality-based Toxics Control (EPA, 1991) might provide some insight in developing water
quality-based effluent limitations. Although this EPA manual is intended to address continuous
discharges, it may provide useful information for wet weather flows.
Due to the possible combined effect of pollutant sources (e.g., other point and nonpoint
sources) or the existing condition of the receiving water body, chemical-specific water quality-
based effluent limits established specifically for CSOs might not result in the attainment of WQS
for a particular receiving water body. In these cases, the NPDES permitting authority should
consider developing one or more total maximum daily loads (TMDLs) for the receiving water
body for the pollutants in CSOs exceeding WQS. (See Section 3.5,1.4 for additional discussion
5.3 August 1995
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Chapter 5 _ Post-Phme II Permitting
of TMDLs.) If a TMDL is established for a receiving water body to control all pollutant
sources of a particular pollutant, the numeric water quality-based effluent limits for that pollutant
in a CSO must be consistent with the wasteload allocation established for the CSOs (see 40 CFR
After the permittee has completed construction of the selected CSO controls, the permit
writer can consider for the last Phase n permit or the first post-Phase II permit the use of
biocriteria, sediment criteria, and whole effluent toxicity testing to evaluate the overall effect of
CSOs on receiving water bodies. Use of these requirements will depend on the need to 1) assess
toxicity in the receiving water body, 2) prevent future impacts, or 3) remediate existing receiving
water body degradation. Again, the permit writer should consult with the appropriate State
WQS authorities and enforcement staff to determine whether such requirements in the permit are
warranted and to establish the specific requirements for the CSOs of concern.
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APPENDIX A
COMPILATION OF EXAMPLE CSO PERMIT CONDITIONS
This appendix is a compilation of all of the example CSO permit cofiditions contained in the
exhibits in Chapters 3 and 4 of this manual, it is intended for reference purposes only, and does
not necessarily represent the Agency's recommendations for CSO permit language in all cases.
Permit conditions should be developed based on careful consideration of site-specific factors.
PHASE I PERMIT
The permittee is authorized to discharge from the CSO outfalls listed below and additional CSO
outfalls within the boundaries of the permittee's jurisdiction identified after the effective date of
the permit. The permittee shall ensure that all CSOs from the CSS comply with the
requirements of [Insert appropriate permit sections containing CSO requirements] and other
pertinent portions of this permit,
Outfall Number Overflow Outfall Location Receiving...W|ter.B.Qdy
[insert number] [insert latitude/longitude [insert name of
(street address optional)] receiving water body]
I. Effluent Limits
A. Technology-based requirements for CSOs
The permittee shall comply with the following technology-based requirements:
1. The permittee shall implement proper operation and maintenance programs for the
sewer system and all CSO outfalls to reduce the magnitude, frequency, and duration
of CSOs. The program shall consider regular sewer inspections; sewer, catch basin,
and regulator cleaning; equipment and sewer collection system repair or replacement,
where necessary; and disconnection of illegal connections.
2. The permittee shall implement procedures that will maximize use of the collection
system for wastewater storage that can be accommodated by the storage capacity of
the collection system in order to reduce the magnitude, frequency, and duration of
CSOs.
3. The permittee shall review and modify, as appropriate, its existing pretreatment
program to minimize CSO impacts from the discharges from Eondoinestic users.
[Alternative language for a permittee without aa approved pretreatment
program:] The permittee shall evaluate the CSO impacts from nondomestic users and
take appropriate steps to minimize such impacts.
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Appendix A Compilation of Example CSO Permit CondM&m
4. The permittee shall operate the POTW treatment plant at maximum treatable flow
during all wet weather flow conditions to reduce the magnitude, frequency, and
duration of CSOs. The permittee shall deliver all flows to the treatment plant within
the constraints of the treatment capacity of the POTW,
5. Dry weather overflows from CSO outfalls are prohibited. Each dry weather overflow
must be reported to the permitting authority as soon as the permittee becomes aware
of the overflow. When the permittee detects a dry weather overflow, the permittee
shall begin corrective action immediately. The permittee shall inspect the dry
weather overflow each subsequent day until the overflow has been eliminated.
6. The permittee shall implement measures to control solid and floatable materials in
CSOs.
7.
The permittee shall implement a pollution prevention program focused on reducing
the impact of CSOs on receiving waters.
8. The permittee shall implement a public notification process to inform citizens of when
and where CSOs occur. The process must include (a) a mechanism to alert persons
of the occurrence of CSOs and (b) a system to determine the nature and duration of
conditions that are potentially harmful for users of receiving waters due to CSOs.
9. The permittee shall monitor CSO outfalls to characterize CSO impacts and the
efficacy of CSO controls. This shall include collection of data that will be used to
document the existing baseline conditions, evaluate the efficacy of the technology-
based controls, and determine the baseline conditions upon which the long-term
control plan will be based. These data shall include:
a. Characteristics of combined sewer system including the population served by the
combined portion of the system and locations of all CSO outfalls in the CSS
b. Total number of CSO events and the frequency and duration of CSOs for a
representative number of events
c. Locations and designated uses of receiving water bodies
d. Water quality data for receiving water bodies
e. Water quality impacts directly related to CSOs (e.g., beach closing, floatables
wash-up episodes, fish Mis).
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Appendix A Compilation of Example CS0 Permit CoiuKtwm
B. Water quality-based requirements for CSOs
The permittee shall not discharge any pollutant at a level that causes or contributes to an in-
stream excursion above numeric or narrative criteria developed and adopted as part of [insert
State name] water quality standards,
Site-Specific Language:
1, The permittee shall not discharge any floating debris, oil, grease, scum, foam, or
other objectionable materials that may result in amounts sufficient to be unsightty or
otherwise objectionable or to constitute a nuisance under State law.
2, The permittee shall not discharge settleable solids, sedimentst sludge deposits,
or suspended particles tftat may coat or cover submerged surfaces,
5, The permittee shall not discharge any pollutants thai may impart undesirable
odors, tastes, or colors to the receiving water body or to the aquatic life found
therein, may endanger public health, or may result in the dominance of nuisance
species.
n. Reporting Requirements
A. Reporting implementation of nine muiiminn controls
The permittee shall submit documentation that demonstrates implementation of each of the nine
minimum controls that includes the elements below. The permittee shall submit this
documentation to the permitting authority on or before [insert due date],
[insert appropriate list of documentation items] '
HI. Long-Term Control Plan
The permittee shall develop a long-term control plan that will include the elements contained in
Sections HI.A through DJ.D below and shall submit the plan elements in accordance with the
schedule contained in Section IDLE:
A, Public Participation
The permittee shall prepare and implement a public participation plan that outlines how the
permittee will ensure participation of the public throughout the long-term control plan
development process.
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Appendix A Compilatwn of Example CSO Permit Conditions
B. CSS Characterization
The permittee shall develop and implement a plan that will result in a comprehensive
characterization of the CSS developed through records review, monitoring, modeling, and
other means as appropriate to establish the existing baseline conditions, evaluate the efficacy
of the CSO technology-based controls, and determine the baseline conditions upon which
the long-term control plan will be based. The characterization shall adequately address the
response of the CSS to various precipitation events; identify the number, location,
frequency, and characteristics of CSOs; and identify water quality impacts that result from
CSOs.
To complete the characterization, the permittee shall employ the following methods:
1. Rainfall Records Review. The permittee shall examine the complete rainfall records
for the geographic areas of the CSS and evaluate the flow variations in the receiving
water body to correlate between the CSOs and receiving water conditions,
2, CSS Records Review. The permittee shall review and evaluate all available CSS
records and undertake field inspections and other necessary activities to identify the
number, location, and frequency of CSOs and their location relative to sensitive areas
(as identified in 111.6,4) and to pollution sources, such as significant industrial users,
in the collection system.
3. CSQ and Water Quality Monitoring. The permittee shall develop and submit a
monitoring program that measures the frequency, duration, flow rate, volume, and
pollutant concentration of CSOs and assesses the impact of the CSOs on receiving
waters. Monitoring shall be performed at a representative number of CSOs for a
representative number of events. The monitoring program shall include CSOs and
ambient receiving water body monitoring and, where appropriate, other monitoring
protocols, such as biological assessments, toxicity testing, and sediment sampling.
4. Identification of Sensitive Areas. The permittee shall identify sensitive areas to
which its CSOs occur. These areas shall include Outstanding National Resource
Waters, National Marine Sanctuaries, waters with threatened or endangered species
and their designated critical habitat, waters with primary contact recreation, public
drinking water intakes or their designated protection areas, shellfish beds, and any
other areas identified by the permittee or permitting authority, in coordination with
appropriate State or Federal agencies.
5. CSS and Receiving Water Modeling. The permittee may employ models, which
include appropriate calibration and verification with field measurements, to aid hi the
characterization. If models are used, they shall be identified by the permittee along
with an explanation of why the model was selected and used in the characterization.
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Appendix A Compttation of Example CSO Permit Conditions
C. CSO Control Alternatives
1. Development of CSO Control Alternatives. The permittee shall develop a range of
CSO control alternatives that would be necessary to achieve [insert appropriate
range of levels of control (e.g., zero overflow events per year, an average of 1
to 3, 4 to 7, and 8 to 12 overflow events per year)]. The permittee shall consider
expansion of the POTW treatment plant secondary and primary capacity as an
alternative.
Alternatives presented must give the highest priority to controlling CSOs to the
sensitive areas identified in IILB.4 above. For such areas, the alternatives included
in the plan must (1) prohibit new or significantly increased CSOs, (2) eliminate or
relocate CSOs from such areas wherever physically possible and economically
achievable, except where elimination or relocation would provide less environmental
protection than additional treatment, (3) where elimination or relocation is not
physically possible or economically achievable or would provide less environmental
protection than additional treatment, provide the level of treatment for remaining
CSOs deemed necessary to meet water quality standards for full protection of existing
and designated uses.
2. Evaluation of CSO Control Alternatives. The permittee shall evaluate each of the
alternatives developed in accordance with HI.C.I to select the CSO controls that will
ensure compliance with CWA requirements.
3. Cost/Performaiice_Considerations. The permittee shall develop and submit
cost/performance curves that demonstrate the relationship among the set of CSO
control alternatives that correspond to the ranges identified in III.C.I above,
D. Selected CSO Controls
Once the permittee has selected the CSO controls in consultation with the permitting authority,
the permittee shall submit the following:
1. Implementation Schedule. The permittee shall submit a construction schedule for the
selected CSO controls as part of the implementation schedule. Such schedules may
be phased based on the relative importance of the adverse impacts on water quality
standards and on the permittee's financial capability.
2. Operational Plan. The permittee shall submit a revised operation and maintenance
plan that addresses implementation of the selected CSO controls. The revised
operation and maintenance plan shall maximize the removal of pollutants during and
after each precipitation event using all available facilities within the collection and
treatment system.
3. Post-Construction Compliance MonitoringJ^rograni. The permittee shall develop and
submit a post-construction monitoring program that (a) is adequate to ascertain the
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Appendix A Compilation of Example CSO Permit Conditions
effectiveness of the CSO controls and (b) can be used to verify attainment of water
quality standards, The program shall include a plan that details the monitoring
protocols to be followed, including CSO and ambient monitoring and, where
appropriate, other monitoring protocols, such as biological assessments, whole
effluent toxicity testing, and sediment sampling,
E, Schedule and Interim Deliverables
The following reports shall be developed in accordance with the requirements specified in
Sections in. A through IJI.D and submitted to the permitting authority by the dates specified
below;
1. Public Participation Plan, as required in Section IE, A, shall be submitted on or
before [insert due date].
2. CSS Characterization Monitoring and Modeling Plan, as required in Section IILB,
shall be submitted on or before [insert due date].
3. CSS CbMacteri.2atiQn^onitoring and Modeling Results, including identification of
sensitive areas, as required in Section III.B, shall be submitted on or before [insert
due date].
4. CSO Control Alternatives Identification, as required in Section ffl.C.l, shall be
submitted on or before [insert due date].
5. CS_Q_CQJtttroU Evaluation and Cost Performance Curves for the selected CSO
controls, as required in Sections IH.C.2 and 3, shall be submitted on or before
[insert due date],
6. Implementation..Schedule, as required in Section III.D.I, including any supporting
analyses, shall be submitted on or before [insert due date].
7. Operational Plan revised to reflect selected CSO controls, as required in Section
III.D.2, shall be submitted on or before [insert due date].
8. Post-Construction Compliance Monitoring Plan, as required in Section DGLD.3, shall
be submitted on or before [insert due date],
IV, Special Conditions
This permit may be modified or revoked and reissued, as provided pursuant to 40 CFR 122.62
and 124.5, for the following reasons:
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Appendix A Compilation of Example CSO Permit Conditions
• To include new or revised conditions developed to comply with any State or Federal
law or regulation that addresses CSOs that is adopted or promulgated subsequent to
the effective date of this permit
* To include new or revised conditions if new information, not available at the time of
permit issuance, indicates that CSO controls imposed under rhe permit have failed to
ensure the attainment of State water quality standards
* To include new or revised conditions based on new information generated from the long-
term control plan.
In addition, this permit may be modified or revoked and reissued for any reason specified in 40
CFR 122.62.
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Appendix A Compilation of Example CSO Permit Conditions
PHASED PERMIT
The permittee is authorized to discharge from the outfalls listed below in accordance with the
requirements of [insert appropriate permit sections containing CSO requirements] and other
pertinent provisions of this permit.
Overflow Number Overflow Outfall Location Receiving Water Body
[Insert number] [insert latitude/longitude [insert receiving water
(street address optional)] body]
I. Effluent Limits
A. Technology-based requirements for CSOs
The permittee shall comply with the following technology-based requirements;
1. Conduct proper operations and regular maintenance programs. The permittee shall
implement the operation and maintenance plan for the CSS that will include the
elements listed below. The permittee also shall update the plan to incorporate any
changes to the system and shall operate and maintain the system according to the
plan. The permittee shall keep records to document the implementation of the plan.
Site-Specific Language:
Designation of a Manager for Combined Sewer System. The permittee shall designate
a person to be responsible for the wastewater collection system and serve as the
contact person regarding the CSS.
Inspection and Maintenance of CSS. The permittee shall inspect and maintain all
CSO structures, regulators, pumping stations, and tidegates to ensure that they
are in good working condition and adjusted to minimize CSOs and prevent tidal
inflow. The permittee shall inspect, or cause to be inspected, each CSO outfall
at an appropriate frequency to ensure no dry weather overflows are occurring.
The inspection shall include, but is not limited to, entering the regulator structure
if accessible, determining the extent of debris and grit buildup, and removing any
debris that may constrict flow, cause blockage, or result in a dry weather
overflow. The permittee shall record in a maintenance log book the results of the
inspections. For CSO outfalls that are inaccessible, the permittee may perform
a visual check of the overflow pipe to determine whether or not the CSO is
occurring during dry weather flow conditions.
Provision for Trained Staff. The permittee shall ensure the availability of trained
staff to carry out the operation, maintenance, repair, and testing Junctions required
to ensure c&mpliance with the terms and conditions of this permit. Each staff
member shall receive appropriate training.
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Appendix A Compilation of Example CSO Permit Conditions
Allocation of Funds, for O&M. The permittee shall allocate adequate funds
specifically for operation and maintenance activities. The permittee shall submit
a certification of assurance from the appropriate local government entities that the
necessary funds, equipment, and personnel have been or will be committed to
carry out the O&M plan.
2. Maximize use of the collection system for storage. The permittee shall maximize the
in-line storage capacity. The permittee shall keep records to document
implementation,
Site-Specific Language:
The permittee shall 1) maintain all dams or diversion structures at ifieir current
heights {as of the date of permit issuance) or greater, 2) minimize discharges from
the CSO outfall locations designated as [insert appropriate designation] until the
specified capacity of the /named] Combined Sewer Retention Bdstn t$ used to store
the overflow for later treatment at the plant, and 3} keep m i «rjj of the flow
entering and leaving the [named] Combined Sewer Retention /Lam
3 . Review and modify pretreatmeni program. The permittee shal U , »n: tnuc u > implement
selected CSO controls to minimize the impact of nondome^iiv di^harces on CSOs.
The permittee shall re-evaluate at an appropriate frequent u nether additional
modifications to its pretreatrnent program are feasible or of rr-*-tivj! ^Sue, The
permittee shall keep records to document this evaluation anJ irnpk-meruauon of the
selected CSO controls to minimize CSO impacts result UK- tn»m n^ndomestic
discharges.
Site-Specific Language:
The permittee shall require significant industrial users iSH's > <£ u turning :o the CSS
to minimize batch discharges during wet weather
[Alternative language for a permittee without an appro* ed pretreatment
program:] Actions to minimize impact of nondomestic discharge*- on CSQs. The
permittee shall continue to implement selected CSO controls to minimize CSO
impacts resulting from nondomestie discharges.
4. Maximize flow to POTW treatment plant. The permittee shall operate the POTW
treatment plant at maximum treatable flow during wet weather flow conditions/events
and deliver all flows to the treatment plant within the constraints of the capacity of
the treatment plant. The permittee shall keep records to document these actions.
5. Prohibit combined sewer overflows during dry weather. Dry weather overflows from
CSO outfalls are prohibited. All dry weather overflows must be reported to the
permitting authority within [insert appropriate number of days] days of when the
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Appendix A Compilation of Example CSO Permit Conditions
permittee becomes aware of a dry weather overflow. When the permittee detects a
dry weather overflow, the permittee shall begin corrective action immediately. The
permittee shall inspect the dry weather overflow each subsequent day until the
overflow has been eliminated. The permittee shall record in the inspection log book
dry weather overflows, as well as the cause, corrective measures taken, and the dates
of beginning and cessation of overflow.
6. Control solid and floatable materials in CSOs. The permittee shall implement
measures to control solid and floatable materials in CSOs.
Site-Specific Language:
These control measures shall include:
* Measures to ensure that baffles are in place to control overflows from the
diversion structures or that other means are used to reduce the volume of
floatables.
* Inspection and maintenance of the sewer system so that solid or floatable
materials greater than [insert size] are not present in CSOs.
1. Develop and implement pQllution^pjre^eiitiQnj?rogram. The permittee shall implement
a pollution prevention program focused on reducing the impact of CSOs on receiving
waters. The permittee shall keep records to document pollution prevention
implementation activities.
Site-Specific Language:
This program shall include:
• Street sweeping and catch basin modification or cleaning at an appropriate
frequency to prevent large accumulations of pollutants and debris
• A public education program that informs the public of the permittee's local
laws that prohibit Uttering and the use of phosphate-containing detergents and
pesticides.
• An oil recycling program.
8. Notify the public of CSOs. The permittee shall continue to implement a public
notification plan to inform citizens of when and where CSOs occur. The process
must include:
a. A mechanism to alert persons using all receiving water bodies affected by CSOs
b. A system to determine the nature and duration of conditions that are potentially
harmful to users of these receiving water bodies due to CSOs,
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Appendix A Compilation of Example CSO Permit Conditions
The permittee shall keep records documenting public notification,
Site-Specific Language:
Within 3 montlts of the effective date of this permil, the permittee shall install and
maintain identification signs at all CSO outfalls owned and operated by the permittee.
The permittee must place the signs at or near the CSO outfalls and ensure that the
signs are easily readable by the public.
9. Monitor to effectively characterize CSO, impacts and the .efficacy, of CSQ controls.
The permittee shall regularly monitor CSO outfalls to effectively characterize CSO
impacts and the efficacy of CSO controls.
B. Water quality-based requirements for CSOs
The permittee shall not discharge any pollutant at a level that causes or contributes to an in-
stream excursion above numeric or narrative criteria adopted as part of [insert State name]
water quality standards.
The permittee shall comply with the following performance standards. These standards shall
apply during {insert average design conditions upon wtiiefa controls are based].
1. [The permit writer should select the appropriate standard below.]
The permittee shall discharge no more than an average of [insert appropriate
number: 4? §, or 6] overflow events per year not receiving the treatment specified
below,
[or]
The permittee shall eliminate or capture for treatment, or storage and subsequent
treatment, at least 85 percent of the system-wide combined sewage volume collected
in the combined sewer system during precipitation events under design conditions.
Captured combined sewage shall receive the treatment specified below.
The permittee shall eliminate or remove the following mass of pollutants from the
combined sewage volume collected in the combined sewer system during precipitation
events under design conditions:
[insert x] pounds of [insert pollutant]
[insert y] pounds of [insert pollutant]
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Appendix A Compilation of Example CSO Permit Conditions
[Insert the following language only if the first or second alternative is chosen
above.]
Any combined sewage captured shall receive a minimum of the following treatment:
* Primary clarification or equivalent.
* Solids and floatables disposal
(Insert appropriate dMnfection requirements as necessary to meet State
WQS.]
* Disinfection. Fecal coiiform counts shall be maintained below [insert applicable
level].
[Insert appropriate dechlorination requirements if applicable based on State
WQS,]
II. Long-Term Control Plan
The permittee shall implement and effectively operate and maintain the CSO controls identified
in the long-term control plan. The implementation schedule for these controls shall be as
follows:
Activity. Completion ....... Date
(insert name of activity] I insert date] .
Site-Specific Language:
I. Retention basin
» Complete design of [named] retention basin, [insert date]
• Submit construction drawings for [named} retention basin /insert date]
* Initiate construction of [named] retention basin. /insert date]
* Complete construction of [named] retention basin. /insert date]
2. [Named street] se\ver separation
• Complete design, /insert date]
* Solicit bids. [insert date]
* Award contracts. /insert
NOTE: A compliance schedule exceeding the term of the permit may onl> be included in
the permit if explicitly authorized in the applicable State WQS.
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Appendix A
Compilation of Example CSO Permit Conditions
HI. Monitoring Requirements
Site-Specific Language:
The permittee shall monitor CSOs and report results to the permitting authority in accordance
with the following:
• •.;•., '- Characteristic • ":
'Reporting;, v
; 'Coie ' ;
•.' Units •
,- Parameter* •':
Ammonia
Ammonia
BOD5
BOD*
«~?
Phosphorus
Total Suspended
Solids
Total Suspended
Solids
Fecal Coliform
Bacteria
Monitoring Requirements- • • >;:: .
-Measurement ' ;;
; ; Frequency •'•'.'./,
.'Sample Type
Grab
Composite
Grab
Composite
Composite
Grab
Composite
Grab
/. The grab sample shall be collected within (insert appropriate number] minutes of the
discharge at the following CSO outfalls /insert appropriate identification]. The grab
sample shall be collected /insert appropriate number] times per year.
, 2. The composite sample shall be collected from the start of the discharge until it stops,
with the sample period not to exceed 24 hours at the following CSO outfalls linsert
appropriate identification]. The composite sample shall be collected /insert
appropriate number] times per year, [insert appropriate number] times during the
period from May - October and [insert appropriate number] times during the period
from November - April. The permittee shall submit the results no later than November
30th and May 3Ist, respectively.
*Parameters listed in this exhibit are examples only. The list of parameters to monitor
must be developed on a site-specific basis.
IV. Reporting Requirements
Within 14 days of each completion date specified in [insert appropriate section! of this permit.
the permittee shall submit a written progress report to the permitting authority stating whether
or not the particular activity was completed. If the activity was not completed, the report shall
also include (1) an explanation of the failure to accomplish the activity, (2) actions taken by the
permittee to correct the situation, and (3) an estimate of when the activity will be completed.
A-13
August 1995
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Appendix A Compilation of Example CSO Permit Conditions
V. Special Conditions
A. CSO-related bypass.
A CSO-related bypass of the secondary treatment portion of the POTW treatment plant is
authorized when the flow rate to the POTW treatment plant as a result of a precipitation
event exceeds [Insert flow rate in MGD]. Bypasses that occur when the flow at the time
of the bypass is under the specified flow rate are not authorized under this condition and
are subject to the bypass provision at 40 CFR 122.41(m). In the event of a CSO-related
bypass authorized under this condition, the permittee shall miiumize the discharge of
pollutants to the environment. At a minimum, CSO-related bypass flows must receive
primary clarification, solids and floatables removal, and disinfection. The permittee shall
report any substantial changes in the volume or character of pollutants being introduced into
the POTW. Authorization of CSO-related bypasses under this provision may be modified
or terminated when there is a substantial change in the volume or character of pollutants
being introduced to the POTW. The permittee shall provide notice to the permitting
authority of bypasses authorized under this provision with 24 hours of occurrence of the
bypass.
B. Sensitive area reassessment.
[This permit condition is only appropriate for CSSs with CSOs to sensitive areas that
have not been eliminated or relocated.]
The permittee shall reassess the feasibility of eliminating or relocating CSO outfalls [Insert
outfall identification numbers for CSOs to sensitive areas] discharging to [insert name
of receiving water body or bodies corresponding to each outfal identffiedj. The
permittee shall consider new or improved techniques to eliminate or relocate overflows or
changed circumstances that influence economic achievability. The permittee shall prepare
and submit to the permitting authority a report that presents the results of this reassessment,
including the permittee's recommendations regarding the elimination or relocation of these
outfalls. The permittee shall submit such report no later than [insert date).
C. Reopener clause.
This permit may be modified or revoked and reissued, as provided pursuant to 40 CFR 122.62
and 124,5, for the following reasons:
• To include new or revised conditions developed to comply with any State or Federal
law or regulation that addresses CSOs that is adopted or promulgated subsequent to
the effective date of this permit
* To include new or revised conditions if new information, not available at the time of
permit issuance, indicates that CSO controls imposed under the permit have failed to
ensure the attainment of State WQSs
A-14 August 1995
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Appendix A Compilation of Example CSO Permit
* To include new or revised conditions based on new information resulting from
implementation of the long-term control plan.
In addition, this permit may be modified or revoked and reissued for any reason specified in
40 CFR 122,62.
A-15 August 1995
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APPENDIX B
DEVELOPMENT AND REVIEW OF MONITORING AND MODELING PLAN
The permit writer is likely to require the permittee to develop a monitoring and modeling
plan. This may be required during the application process prior to the development of the
permit or as a permit condition. If, during the review of the plan, the permit writer determines
the plan is lacking information or the scope of the plan is inappropriate, the permit writer should
note the deficiencies and require the plan to be modified and resubmitted. Development of the
monitoring and modeling plan may require an iterative approach to match data, informational
needs, and available resources. The plan may need to change as more knowledge is gained
about the CSS and CSOs through the early steps of data collection.
Exhibit B-l outlines the major elements the monitoring and modeling plan should
generally contain. The permit writer should consider requesting that the permittee submit the
monitoring and modeling plan in a specific format so that critical information can be taken from
the plan and incorporated into the permit as requirements, where appropriate. Extensive
information on the development of a monitoring and modeling plan is contained in the Combined
Sewer Overflows—Guidance for Monitoring and Modeling (EPA, 1995d).
The monitoring and modeling plan should balance the costs of monitoring and modeling
against the information needed to characterize the combined sewer system (CSS), combined
sewer overflows (CSOs), and the receiving water and to develop, implement, and verify the
effectiveness of CSO controls. Since monitoring data and modeling results are important factors
in making CSO control decisions, it is crucial that collected monitoring data accurately represent
the conditions that exist throughout the CSS, CSOs, and the receiving water. Monitoring date
are used as modeling inputs and for model calibration and verification, so accurate,
representative monitoring data are also necessary if the permittee intends to perform modeling
to assist in the selection of the most appropriate CSO controls. In some cases, a permittee may
have a considerable amount of existing data from previous monitoring efforts and may only need
to perform a limited amount of additional monitoring. The permit writer should remember these
August 1995
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Appendix B
Development: and Review of Monitoring and Modeling Plan
Exhibit B-l. Outline of M^jor Monitoring Plan Elements
B-2
August 1995
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Appendix B Development and Review of Monitoring and Modeling Plan
factors when reviewing any proposed monitoring and modeling plan. Although the permit writer
should provide flexibility to allow for scheduling and budget constraints, he or she should not
accept an inadequate monitoring and modeling plan.
A review team that has members knowledgeable in developing and implementing
monitoring programs should be convened to review a proposed monitoring and modeling plan.
If the proposed monitoring and modeling plan does not meet the established goals, the permit
writer should raise these issues and work with the permittee to develop a monitoring and
modeling plan that meets the established objectives. In addition, in some instances, the permit
writer and/or the permittee may need to establish priorities to perform the most critical data
collection first and schedule additional monitoring activities within a reasonable time period.
When reviewing a monitoring and modeling plan and developing monitoring requirements
in the permit, the permit writer should consider sampling locations, pollutants to be monitored,
frequencies, duration including periods of rainfall or other seasonal issues, sample types, and
analytical methods, among other appropriate factors as listed in Exhibit B-l. These factors are
described in the following discussion using examples. The specific sampling details are
important because the permit writer may want to incorporate them into the permit:
* Sampling Location—Generally, the permittee will need to collect rainfall data, flow
data, and pollutant data to define the CSS's hydraulic response to rainfall and
determine CSG flows and pollutant loadings.
- If sufficient existing rainfall data are not available, the permittee may need to
install rain gages to collect the data. Rain gages should be located so that they
provide data that are representative of the entire CSS drainage area.
- To assess flow patterns and volume in the CSS, the permittee may need to select
some sampling locations along various trunk lines of the collection system if flow
data from existing monitors and at hydraulic controls (e.g., pump stations) are not
sufficient. The permittee should also sample the portions of the collection system
that are likely to receive significant pollutant loadings (e.g., areas where
significant industrial users are located) to obtain flow and loading data.
B-3 . August 1995
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Appendix B Development and Review of Monitoring and Modeling Plan
- When monitoring CSOs, if it is not feasible to monitor all CSOs, a defined
percentage of the total outfalls in the system should be sampled, The specific
number of outfalls to be monitored should be based on the size of the collection
system, the total number of overflow locations, the number of different receiving
water bodies, and potential and known impacts. If only selected locations are
sampled, they should represent the system as a whole or represent the worst-case
scenario. For example, if all CSOs are not monitored, selected locations could
be chosen that represent overflows that occur most frequently, have the largest
pollutant loading or flow volume, or discharge to sensitive areas.
- For receiving water monitoring, the selection of appropriate locations depends on
the characteristics of the receiving water (e.g., size of the water body, horizontal
and vertical variability), the pollutants of concern, and the location of sensitive
areas,
• Pollutants—CSSs need to be monitored for pollutants of concern, including pollutants
with water quality criteria for the specific designated use(s) of the receiving water
and pollutants key to the attainment of the designated use(s). The pollutants or
classes of pollutants recommended for monitoring in most cases include biochemical
oxygen demand or dissolved oxygen, total suspended solids, settleable solids,
nutrients, toxic pollutants reasonably expected to be present, and bacteriological
indicators. In some cases, specific pollutants should be measured; in other cases,
surrogates of a pollutant class may be used. For example, heavy metals may be
addressed by only monitoring copper, lead, and zinc because these are the metals
most commonly found in CSOs. If water quality standards for mercury and arsenic
are being exceeded, however, then they should be monitored. The selection of
pollutants to be monitored should also be based on the characteristics of the
nondomesttc discharges to the collection system or watershed. Receiving water
monitoring may include biological assessment and sediment monitoring in addition
to the pollutants listed above.
* Frequency of Monitoring—Frequency of monitoring should reflect the type and
amouot of data needed to achieve the program goals. Monitoring programs may
include:
- Sampling a certain size precipitation event (e.g., 3-month, 24-hour storm)
- Sampling all precipitation events that result in overflows
- Sampling a certain number of precipitation events (i.e,, monitor until five storms
are collected of a certain minimum size)
The precipitation events to be sampled should be separated by an adequate duration
so that a sample of worst-case conditions is collected. The National Pollutant
Discharge Elimination System (NPDES) Storm Water Program uses the criterion that
the duration between the beginning of die precipitation event sampled and the end of
the previous measurable precipitation event be at least 72 hours.
B-4 August 1995
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Appendix B Development and Review of Monitoring and Modeling Plan
An assessment of the monitoring frequency should include consideration of the
following criteria:
- Relative risk of CSO impacts. If facilities discharge to sensitive areas or high
quality waters, more frequent monitoring may be warranted. For example, the
monitoring frequency should increase in an area where human contact occurs
through swimming, boating, and other recreational activities.
- Variability of discharge. CSOs with variable flows should be monitored more
frequently than CSOs with relatively consistent flows,
For receiving water characterization, the monitoring plan should target seasons, flow
regimes, and other critical environmental conditions.
» Duration of Monitoring Program—The duration of the monitoring program is
generally based on sampling a number of storm events adequate to provide the data
needed to either calibrate and validate the CSS hydraulic model, or to provide
sufficient data to evaluate CSO control alternatives where a model is not used.
During that period (which generally may be a season or several months), storms of
varying intensity, antecedent dry days, and total volume should be monitored to
represent the range of conditions experienced by the CSS. The duration should be
sufficient to sample enough storm events to readily estimate means and variations of
pollutant concentrations in CSOs. The sampling period for flow and occurrence
monitoring may extend for the duration of the permit; the sampling period for
instream monitoring or other special studies may be relatively short. When feasible,
permit writers should coordinate monitoring requirements if the data will be used for
the same purpose (e.g., calculation of a wasteload allocation).
* Sample Type—The sample type may be composite or grab, depending on site-
specific conditions and the intended use of the data. To determine average loadings
of pollutants to the receiving stream, it may be most appropriate to collect flow-
weighted composites. Because CSOs may be intermittent and the volume dependent
upon precipitation events, however, it may not be appropriate to collect 24-hour
composite samples, which are used for continuous nondomestic and municipal
wastewater discharges. Instead it may be more appropriate to collect a composite
over the duration of the entire discharge. It is critical that the permittee use sample
types that will adequately characterize CSOs. However, the permit writer should be
aware that the composite samples are more resource intensive than grab samples.
Grab samples may be appropriate if only approximate levels of pollutants are needed
or if the most important concern is the impact of worst-case conditions (i.e., first 15
or 30 minutes of overflow). In addition, grab samples should be collected for
pollutant parameters not amendable to compositing (e.g., pH, bacteria).
B-5 August 1995
-------
Appendix B Development and Review of Monitoring and Modeling Plan
Analytical Methods—Analytical methods should be selected pursuant to 40 CFR Part
136, which references one or more of the following:
- Test methods in Appendix A to 40 CFR Part 136 (i.e., Methods for Organic
Chemical Analysis of Municipal and Industrial Wastewater).
- Standard Methods for the Analysis of Water and Wastewater (most current EPA-
approved edition)
- Methods far the Chemical Analysis of Water and Wastes
The analytical methods contained in Part 136 are test methods designed only for
specified pollutants or parameters. For other parameters, it may be necessary for the
permit writer to specify the analytical methods required on a case-by-case basis. For
example, Part 136 does not contain biomonitoring test procedures, therefore, the
permit writer will need to specify the methods. EPA has published recommended
biomonitormg test protocols.
In reviewing these elements of the monitoring and modeling plan, a" well as the other
elements listed in Exhibit B-l, the permit writer should consider the anv»un: *>t existing data the
permittee has collected, A permittee with a substantial set of existtnr ii.itj nu\ not need to-
conduct additional monitoring for all the conditions addressed above
The permit writer should also determine whether models or dau arus M<- methodologies
specified in the monitoring and modeling plan are appropriate for thi- CSS ark] the type of data
being collected. If the monitoring and modeling objectives mduJi- mi'»rnuunnal needs,
modeling, or statistical, graphical, or other data analyses, technique*- should he specified so
reliable and consistent information is obtained. This wiU ensure that duu u'lleuton efforts meet
the needs of the analytical methods. Review by the appropriate member- ot the review team
(i.e., statisticians or other experts in monitoring and modeling plan development and
implementation) will ensure that the proposed data collection and analytical methodologies will
meet the stated objectives of the monitoring and modeling plan.
Each plan will need to be evaluated on a case-by-case basis. The permit writer may
enlist the EPA permitting and/or monitoring staff in reviewing the monitoring and modeling
plans submitted by the permittee. If the review team determines that the proposed plan is
B-6 August 1995
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Appendix B Development and Review of Monitoring and ModsUng Plan
inadequate, then the permit writer should work with the permittee to address deficiencies in the
plan.
B-7 August 1995
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APPENBKC
The permit writer may find this checklist useful in reviewing NMC documentation
submitted by the permittee. However, because some items listed in the checklist may not be
applicable to the permittee, there may not be a "yes" answer to every question.
C-l August 1995
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Suggested Nine Minimum Controls Evaluation Checklist
Evaluation Criteria
Proper Operation and Regular Maintenance Programs for tlie
CSS and CSO Outfalls .. • '
Docs the O&M program describe the system, including an
inventory of all CSO structures, equipment, and treatment
facilities?
Does the O&M program provide procedures for keeping this
inventory current?
Will the O&M program be effective in reducing the number,
frequency, and pollutant loadings of CSOs?
Does the O&M program:
Include routine inspection, cleaning and maintenance, and
repair schedules for all inventoried CSO outfalls, interceptors,
regulators, pumping stations, and equipment including
schedules and inspection frequencies that are appropriate for
the system?
Include inspections for dry weather overflows and illicit
connections?
Provide operating procedures and specifications for all
equipment, structures, facilities, CSO outfalls, and off-line
storage structures, including the hydraulic capacities of the
collection and treatment systems, the storage capacities of the
collection and treatment systems, and off-line storage
capacity?
Have in place operating procedures that reflect she hcst me of
the system's flow and rouling control"; ?<» minimi/r C'MK.
including procedures to identify and corral t'SS .«n! t s*>
problems?
Require logs or other documentation «»f i«»m|>U-u-il ,K
-------
Suggested Nine Minimum Controls Evaluation Checklist
Evaluation Criteria
Allocate resources for O&M program implementation,
including staffing level and funding, equipment, and training?
Evaluation Result (circle one)
'Maximum Use of the Collection System for Storage
Has the permittee:
Identified portions of the CSS usable for storage and
determined the CSS storage capacity, including configuration,
size, and pump station capacity?
Identified appropriate minor modifications to increase storage
(e.g., raising existing weirs)?
Identified potential off-line storage at existing facilities?
implemented procedures for maximizing CSS storage
capacity?
Evaluation Result (circle one)
Y* '
Adequate
Adequate
No
Inadequate
Inadequate
N/A .;
Other
Other
Remarks
t
-------
Suggested Nine Minimum Controls Evaluation Checklist
Evaluation Criteria ''"''*..'...
Review and Modification of Pretreatraeist Programs
..;..•; ',...-. .. ...... :•::• -. .<.•:. .... ;.•:.•„•....-..•..• -.-. •_•:• _•. • , ;,<„• ,,*».•...-:-:•-,., •; :
Has the permittee:
Determined whether the CSS receives nondomestic wastewater
discharges?
Prepared an inventory of nondomestic users who discharge to
the CSS and evaluated the discharge constituents and suspected
impacts from such users?
Evaluated the potential for regulating either the volume or
pollutant loadings from nondomestic users to the CSS during
wet weather flow conditions?
Modified the pretreatment program as determined appropriate?
Evaluation Result (circle one)
•y<*. :
Adequate
$*•;
Inadequate
N/A:?
••- '-.; ;:'•••'. •'
Other
'••'?Z'""n'- -;....^ Bemwlsa • .:,/:-: .
-:"'"":;:;:.""'-:. : | ^ .v!.;.; . ...i-::.;:. ,-; .. '.' .. -'^ - - '
t
-------
Suggested Nine Minimum Controls Evaluation Checklist
Evaluation Criteria
Maximisation of Bloy to POTW Treatment Plant
Has the permittee;
Compared existing flow conditions to the design capacity of
the collection system?
Identified actions that could be taken to increase flows to the
POTW treatment plant during wet weather flow conditions
without significantly affecting treatment performance?
Conducted plant tests to determine the plant capability to treat
higher flows during wet weather How conditions or
determined, using available historical data, the maximum flow
that can be treated?
Developed, implemented, and documented implementation of a
flow maximization plan during wet weather flow conditions?
Evaluation Result (circle one)
Y«
Adequate
No
Inadequate
N/A.
Other
Remarks
a
I-
O
1
Oi
-------
Suggested Nine Minimum Controls Evaluation Checklist
Evaluation Criteria
Prohibition of CSOs During. Dry Weather Flow Conditions
Has the permittee:
Developed adequate procedures to document where and when
dry weather overflows occur, including follow-up inspections
after dry weather overflows occur?
Developed and instituted procedures to prevent and eliminate
dry weather overflows, including routine inspection of
regulators and CSO outfalls as part of the O&M plan?
Evaluation Result (circle one)
Y«. .
Adequate
N®
Inadequate
N;A
Other
Remarks
•
•*
t
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Suggested Nine Minimum Controls Evaluation Checklist
Evaluation. Criteria
Control of S,otkJ and Floatable Materials in CSO*
Has the permittee;
Evaluated the following technologies for the control of solid
and floatable materials in CSOs:
Screening materials using baffles, screens, and netting'.'
Skimmer boats?
Skimming from water body surface wish booms at outfalls
in confined areas?
Source control, which may be addressed under the
pollution prevention program for CSO outfalls?
Identified and addressed problems that may be created by the
installation of the control technology?
Implemented the appropriate control technology, considered
and provided justification that the technology is appropriate for
the site conditions, and is conducting associated inspections
and regular maintenance?
Evaluation Result
-------
Suggested Nine Minimum Controls Evaluation Checklist
-' • Evaluation Criteria.
Pollution Prevention Program
Has the permittee;
Evaluated source control measures both at the government
level (e.g., street cleaning; banning or substitution of
products, such as plastic food containers; controlled use of
pesticides, fertilizers, and other hazardous substances at public
facilities) and among the public (e.g., used oil recycling,
household hazardous waste collection)?
Included a wide-reaching public education program?
Evaluated mechanisms to encourage water conservation (e.g.,
public outreach, structuring of water/sewer service charges,
local ordinance provisions)?
Allocated adequate resources to conduct pollution prevention
program activities?
Implemented and maintained detailed records of pollution
prevention activities?
Promoted the use of industrial/construction BMPs for storm
water?
Evaluation Result (circle one)
Ye*
•
Adequate
No
Inadequate
N/A
Other
Remarks
f
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Suggested Nine Minimum Controls Evaluation Checklist
Evaluation Criteria ' - • . • ,' •
Public notification _ - , ' • . " •• • ; - , •
Has the permittee:
Evaluated options for public notification to ensure that the
public receives adequate notification of CSO occurrences and
CSO impacts?
Implemented notification procedures regarding the presence of
contaminants at critical levels in the receiving water bodies
due to CSOs?
Implemented procedures that notify persons reasonably
expected to be affected by the CSO?
Documented CSO occurrences and associated notifications?
Installed identification signs at each CSO outfall?
Evaluation Result (circle one)
Y«s ' .
Adequate
No
Inadequate
: N/A1 ..
Other
• . . "• ' , Remarks' ' -
-------
APPENDEXD
The permit writer may find this checklist useful in reviewing the long-term control plan
submitted by the permittee. However, because some items listed in the checklist may not be
applicable to the permittee, there may not be a "yes" answer to every question.
August 1995
-------
Suggeeted Long-Term Control Plan Evaluation Checklist
'Evaluation Criteria
Public Participation
Does the public participation process seek to actively involve rate
payers, industrial users of the CSS, persons near the impacted
waters, and persons who use the impacted waters?
Does the public participation plan document how the public was
notified of public participation events?
Docs the public participation plan include a record of the public
participation events, including the number of people attending and a
record or summary of comments?
Does the public participation plan contain a summary of comments
anti the changes or decisions made in response to public comments?
Evaluation Result (circle one)
Yes •
Adequate
. No
Inadequate
N/A
Other
Remarks
-------
Suggested Long-Term Control Plan Evaluation Checklist
- Evaluation Criteria- •, • rh
-------
Suggested Long-Term Control Plan Evaluation Checklist
Evaluation Criteria
CSO Cdntrol Alternative • -
Did the permittee develop a comprehensive list of CSO control
alternatives?
Did this list include alternatives from each of the four general
categories— source controls, collection system controls, storage, and
treatment technologies (described in Combined Sewer
Overflows—Guidance far Long-1 «?» Control Plan fEPA, )995a{)?
Are the CSO control alternatives that were considered described?
Does the plan describe the process by which the CSO control
alternatives were developed?
Does this plan compare the environmental benefits of the CSO
control alternatives?
Is cost/performance information (including curves) for each of the
CSO control alternatives provided?
Do the cost/performance analyses evaluate a range of levels of
controls that were developed based on the permittee's site specific
conditions (e.g., zero overflow events per year, and averages of 1
to 3, 4 to 7, and 8 to 12 overflow events per year)?
Does plan describe the approach used to screen the list of CSO
control alternatives, including the recommended screening criteria?
Do the screening criteria include performance factors.
implementation and operation factors, sue)) as COSH, ami
environmental impacts (described in Combined AVurr
Overflows—Guidance for Long-Tetm GWM/ I'lui (f I1 \ ) ''''*
-------
Suggested Long-Term Control Plan Evaluation Checklist
Evaluation Criteria
.Sel«d?tCeS0'Controk. ... . , ' • . .. . j , -.
Is the presumption or demonstration approach used?
Does the plan identify the reasons for selecting certain CSO
controls?
Were reasons for rejecting specific CSO controls reasonable?
Have the NMC been integrated into the permittee's description of
its selected CSO controls?
Will the selected CSO controls eliminate all CSO points to sensitive
areas?
If not, do the data support the permittee's conclusion that
elimination is not physically possible or economically
achievable?
If CSO outfalls to sensitive areas remain:
Will these CSOs receive treatment?
Will the CSO controls be sufficient to provide for the attainment
of WQS?
Have control efforts for other point and nonpoint sources of
pollutants within the watershed been considered'?
Will the CSO controls provide treatment or removal of floaiables
and settleable solids equivalent to that achieved by primary
clarification?
Is the mechanism for solids and floatables disposal described?
Will the disinfection of effluent be necessary based on applicable
WQS?
If yes, is disinfection proposed as part of the CSO controls?
If yes, will removal of harmful disinfection chemical residuals
be necessary?
If no, does the infoiroation support the conclusion that
disinfection is not necessary?
Yes'
... !*».."
- -,
. it/A ...
Remarks •
•
*
3
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Suggested Long-Term Control Plan Evaluation Checklist
- Evaluation Criteria
Do the selected CSO controls provide the maximum pollution
reduction benefits reasonably attainable?
Will the selected CSO controls provide for the attainment of WQS?
If WQS cannot be met because of sources other than CSOs, has the
permittee provided information on the other sources and natural
background conditions?
Are the selected CSO controls designed to allow cost-effective
expansion or cost-effective retrofitting if additional controls are
determined necessary to provide for the attainment of WQS?
Has a TMDL been developed for the watershed?
If so, has the permittee considered the TMDL in developing its
LTCP?
Evaluation Result (circle one)
' Yes
Adequate
No
^
Inadequate
N/A
Other
Remarks
-------
Suggested Long-Term Control Plan Evaluation Checklist
Evaluation Criteria
Implementation Schedule
Do any phased construction schedules consider:
Eliminating CSOs to sensitive areas?
Use Impairment?
Do any phased construction schedules include an analysis of
financial capability?
Did the permittee evaluate the following faciors:
Median household income?
Total annual wastewiter and CSO control costs per household as
a percent of median household income?
Overall net debt as a percent of full market property value?
Property tax revenues as a percent of fyll market property
value?
Property tax collection rate?
Unemployment?
Bond rating?
Did the permittee evaluate the following factors:
Grant and loan availability?
Previous and current residential, commercial, and industrial
sewer user fees and rate structures?
Other viable funding mechanisms Mid sources of financing?
Does the schedule include milestones for all major implementation
activities, including environmental reviews, siting of facilities, site
acquisition. Army Corps of Engineers permitting, etc.?
Evaluation Result (circle one)
Yes
Adequate
No
Inadequate
N/A
Other
Remarks
•.
I
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Suggested Long-Term Control Plan Evaluation Checklist
-• }:* * • Evaluation Criteria
Post-Construction Compliance Monitoring
Does the monitoring program include monitoring of CSOs that are
representative of the impacts to receiving waters?
Docs the monitoring program include ambient receiving water body
monitoring at representative CSOs, as well as monitoring prior to
CSO impacts?
Has the receiving water body monitoring program been coordinated
with any ongoing or planned State programs and programs of other
permittees within the same watershed?
Does the monitoring program include any biological parameters
(e.g., fish, xooplankton)?
Does the monitoring program address pollutants included in the
water quality criteria for the specific designated uses(s) of the
receiving water, pollutants key to the attainment of ihe designated
water use(s), and pollutants affected by the CSO controls?
Yes
No
N/A '
Remarks
I
I
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Suggested Long-Term Control Plan Evaluation Checklist
Evaluation Criteria
Does the monitoring program include appropriate measures of
success?
Evaluation Result (circle one) •
Comprehensive Evaluation Result (circle one)
' ' **•__,
Adequate
Adequate .
".-!*» !
Inadequate
^ Inadequate
... N*A".;
Other
Other-
• •• • • ;\Rw«tarks , .'.
-------
GLOSSARY1
Average Number of Overflow Events Per Year—The total number of combined sewer
overflow events that occurred during the term of the permit divided by the permit term in years.
Combined Sewer Overflow—The discharge from a combined sewer system to a receiving water
of the United States prior to reaching the publicly owned treatment works treatment plant.
Combined Sewer Overflow Event—The discharges from any number of points in the combined
sewer system resulting from a single wet weather event that do not receive minimum treatment
(i.e., primary clarification, solids disposal, and disinfection, where appropriate). For example,
if a storm occurs that results in untreated overflows from 50 different CSO outfalls within the
CSS, this is considered one overflow event.
Combined Sewer System—A wastewater collection system owned by a State or one or more
municipalities (as defined by Section 502(4) of the Clean Water Act) which conveys sanitary
wastewaters (domestic, commercial, and industrial wastewaters) and storm water through a
single-pipe system to a publicly owned treatment works treatment plant (as defined in 40 CFR
403.3(p)),
Dry Weather Flow Conditions—Hydraulic flow conditions within the combined sewer system
resulting from one or more of the following: flows of domestic sewage, ground water
infiltration, commercial and industrial wastewaters, and any other non-precipitation event related
flows (e.g., tidal infiltration under certain circumstances). Other non-precipitation event related
flows that are included in dry weather flow conditions will be decided by the permit writer based
on site-specific conditions.
Dry Weather Overflow—A combined sewer overflow that occurs during dry weather flow
conditions.
Precipitation Event—An occurrence of rain, snow, sleet, hail, or other form of precipitation.
Precipitation events are generally characterized by parameters of duration and intensity (inches
or millimeters per unit of time). This definition will be highly site-specific. For example, a
precipitation event could be defined as 0.25 inches or more of precipitation in the form of rain
or 3 inches or more of precipitation in the form of sleet or snow, reported during the preceding
24-hour period at a specific gaging station. A precipitation event could also be defined by a
minimum time interval between measurable amounts of precipitation (e.g., 6 hours between the
end of rainfall and the beginning of the next rainfall).
Primary Clarification or Equivalent—The level of treatment that would typically be provided
by one or more treatment technologies under peak wet weather flow conditions. Options for
definitions were developed solely for the purposes of this guidance document.
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Glossary
defining primary clarification include a design standard (e.g., side wall depth and maximum
overflow rate), a performance standard (e.g., percent removal), or an effluent standard (e.g.,
concentration of pollutants). "Equivalent to primary clarification" is site-specific and includes
any single technology or combination of technologies shown by the permittee to achieve primary
clarification under the presumption approach. The permittee is responsible for showing
equivalency to primary treatment as part of the evaluation of CSO control alternatives during
LTCP development, Primary clarification is discussed in more detail in the Combined Sewer
Overflows-Guidance for Long-Term Control Plan (EPA, 1995a).
Sensitive Areas—Areas of particular environmental significance or sensitivity that could be
adversely affected by a combined sewer overflow, including Outstanding National Resource
Waters, National Marine Sanctuaries, water with threatened or endangered species, waters with
primary contact recreation, public drinking water intakes, shellfish beds, and other areas
identified by the permittee or National Pollutant Discharge Elimination System permitting
authority, in coordination with the appropriate State or Federal agencies.
Solid and Floatable Materials—Solid or semi-solid materials should be defined on a case-by-
case basis determined by the control technologies proposed by the permittee to control these
materials. The term generally includes materials that might impair the aesthetics of the receiving
water body.
Wet Weather Flow Conditions—Hydraulic flow conditions within the combined sewer system
resulting from a precipitation event. Since the definition of precipitation event is site-specific,
the permit writer should evaluate and define certain site-specific weather conditions that typically
contribute to wet weather flow. EPA encourages permit writers to include snowmelt as a
condition that typically contributes to wet weather flow.
G-2 " August 1995
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REFERENCES
U.S. Environmental Protection Agency (EPA). 1995a. Combined Sewer
Overflows—Guidance for Long-Term Control Plan (EPA 832-B-95-OQ2).
EPA. 1995b. Combined Sewer Overflows—Guidance for Nine Minimum Controls
(EPA 832-B-95-QQ3).
EPA. 1995c. Combined Sewer Overflows—Guidance for Screening and Ranking
(EPA 832-B-95-Q04).
EPA. 1995d. Combined Sewer Overflows—Guidance for Monitoring and Modeling
(EPA 832-B-95-005).
EPA. 1995e. Combined Sewer Overflows—Guidance for Financial Capability Assessment
(EPA 832-B-95-006).
EPA. 1995f. Combined Sewer Overflows—Guidance for Funding Options
(EPA 832-B-95-0Q7).
EPA. 1995g. Combined Sewer Overflows—Guidance for Permit Writers
(EPA 832-B-9S-008).
EPA. 1995h. Combined Sewer Overflows—Questions and Answers on Water Quality
Standards and the CSO Program (EPA 832-B-95-Q09).
EPA. 1993. Training Manual for NPDES Permit Writers. (EPA 833-8-93-003).
EPA. 1991. Technical Support Document for Water Quality-based Toxics Control.
(EPA/505/'2-90-001), PB91-127415.
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