&EPA
United States
Environmental Protection
Agency
SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL
FOR THE LONG TERM 2 AND STAGE 2 DBP RULES
Office of Water (4601)
EPA815-R-07-017
March 2007
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U.S. Environmental Protection Agency
Office of Water (4601)
1200 Pennsylvania Avenue NW
Washington, DC 20460
EPA815-R-07-017
http://www.epa.gov/safewater/disinfection/staqe2/compliance.html
March 2007
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Purpose:
The purpose of this guidance manual is to provide technical information for water
systems and states to assist them with complying with the Stage 2 Disinfectant and Disinfection
Byproducts Rule, the Long Term 2 Enhanced Surface Water Treatment Rule, and other Safe
Drinking Water Act (SOWA) regulations. This guidance is not a substitute for applicable legal
requirements, nor is it a regulation itself. Thus, it does not impose legally binding requirements
on any party, including EPA, states, or the regulated community. Interested parties are free to
raise questions and objections to the guidance and the appropriateness of its use in a particular
situation. Although this manual describes many methods for complying with SDWA
requirements, the guidance presented here may not be appropriate for all situations, and
alternative approaches may provide satisfactory performance. The mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
Authorship:
This manual was developed under the direction of EPA's Office of Ground Water and
Drinking Water and was prepared by The Cadmus Group, Inc. and HDR, Inc. Questions
concerning this document should be addressed to:
Sarah Bahrman
Office of Ground Water & Drinking Water
U.S. Environmental Protection Agency
Mail Code 4607M
1200 Pennsylvania Avenue NW
Washington, DC 20460-0001
Email: Bahrman.Sarah@epamail.epa.gov
Simultaneous Compliance Guidance Manual 3 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Acknowledgments:
Gary Burlingame — Philadelphia Water Department
Chris Hill — Malcolm Pirnie, Inc.
Rick Sakaji — California Department of Health Services
David Schendel — Malcolm Pirnie, Inc.
Ann Arbor Utilities
City of Englewood, Colorado
Gulf Coast Water Authority
City of Higginsville, Missouri
Kansas City Water Services
Owenton Water Works and Kentucky American TriVillage
Palm Beach County Water Utilities Department
City of Poughkeepsie, New York
Skagit County Public Utility District #1
City of Tampa, Florida
Washington Suburban Sanitary Commission
Village of Waterloo, New York
City of Wilmington, North Carolina
Simultaneous Compliance Guidance Manual 4 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Table of Contents
Table of Contents i
List of Exhibits v
List of Abbreviations and Acronyms vi
1. Introduction 1-1
1.1 What is the purpose of this guidance manual? 1-1
1.2 What is "Simultaneous Compliance"? 1-2
1.3 Does this manual address compliance with environmental regulations other
than SDWA regulations? 1-2
1.4 Who should use this guidance manual? How should it be used? 1-2
1.5 How is this manual organized? 1-7
1.6 Can I rely on this guidance manual alone to make compliance decisions? 1-11
1.7 Are there quick references I can use to screen for potential simultaneous
compliance problems? 1-11
1.8 Where can I get help achieving simultaneous compliance? 1-12
1.9 What additional resources are available? 1-12
2. Quick Reference Materials for Simultaneous Compliance 2-1
3. Improving and Optimizing Current Operations 3-1
3.1 Source Management 3-2
3.1.1 Advantages of Source Management 3-4
3.1.2 Potential Operational and Simultaneous Compliance Issues Associated
with Source Management Changes 3-5
3.1.3 Recommendations for Gathering More Information 3-10
3.2 Distribution System Best Management Practices 3-11
3.2.1 Advantages of Distribution System BMPs 3-16
3.2.2 Potential Operational and Simultaneous Compliance Issues Associated
with Distribution System BMPs 3-17
3.2.3 Recommendations for Gathering More Information 3-19
3.3 Moving the Point of Chlorination 3-21
3.3.1 Advantages of Moving the Point of Chlorination 3-22
3.3.2 Potential Operational and Simultaneous Compliance Issues
Associated with Moving the Point of Chlorination 3-23
3.3.3 Recommendations for Gathering More Information 3-28
3.4 Decreasing pH 3-30
3.4.1 Advantages of Decreasing pH 3-30
3.4.2 Potential Operational and Simultaneous Compliance Issues Associated
with Decreasing pH 3-32
3.4.3 Recommendations for Gathering More Information 3-35
3.5 Reducing Chlorine Dose under Warm Water Conditions 3-37
3.5.1 Advantages of Reducing Chlorine Dose under Warm Water Conditions 3-37
3.5.2 Potential Operational and Simultaneous Compliance Issues Associated
with Reducing Chlorine Dose under Warm Water Conditions 3-38
3.5.3 Recommendations for Gathering More Information 3-39
3.6 Modifying Pre-sedimentation Basin Operations 3-41
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Table of Contents (continued)
3.6.1 Advantages of Modifying Pre-sedimentati on Basin Operations 3-41
3.6.2 Potential Operational and Simultaneous Compliance Issues Associated
with Modifying Pre-sedimentation Basin Operations 3-42
3.6.3 Recommendations for Gathering More Information 3-43
3.7 Enhanced Coagulation 3-44
3.7.1 Advantages of Enhanced Coagulation 3-44
3.7.2 Potential Operational and Simultaneous Compliance Issues Associated
with Enhanced Coagulation 3-46
3.7.3 Recommendations for Gathering More Information 3-51
3.8 Enhanced Softening 3-53
3.8.1 Advantages of Enhanced Softening 3-54
3.8.2 Potential Operational and Simultaneous Compliance Issues Associated
with Enhanced Softening 3-55
3.8.3 Recommendations for Gathering More Information 3-58
4. Installing New Total Organic Carbon or Microbial Removal Technologies 4-1
4.1 Granular Activated Carbon 4-1
4.1.1 Advantages of GAC 4-2
4.1.2 Potential Operational and Simultaneous Compliance Issues Associated
with Using GAC 4-3
4.1.3 Recommendations for Gathering More Information 4-6
4.2 Microfiltration/Ultrafiltration 4-8
4.2.1 Advantages of MF/UF 4-8
4.2.2 Potential Operational and Simultaneous Compliance Issues Associated
with MF/UF 4-9
4.2.3 Recommendations for Gathering More Information 4-11
4.3 Nanofiltration 4-13
4.3.1 Advantages of Nanofiltration 4-13
4.3.2 Potential Operational and Simultaneous Compliance Issues Associated
with Nanofiltration 4-14
4.3.3 Recommendations for Gathering More Information 4-17
4.4 Other Microbial Removal Technologies 4-19
4.4.1 Advantages 4-20
4.4.2 Potential Operational and Simultaneous Compliance Issues 4-21
4.4.3 Recommendations for Gathering More Information 4-23
5. Alternative Disinfection Strategies 5-1
5.1 Chloramines 5-1
5.1.1 Advantages of Chloramines 5-1
5.1.2 Potential Operational and Simultaneous Compliance Issues Associated
with Chloramines 5-3
5.1.3 Recommendations for Gathering More Information 5-10
5.2 Ozonation 5-13
5.2.1 Advantages of Ozonation 5-13
5.2.2 Potential Operational and Simultaneous Compliance Issues Associated
with Ozonation 5-15
5.2.3 Recommendations for Gathering More Information 5-21
5.3 Ultraviolet Light (UV) 5-24
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Table of Contents (continued)
5.3.1 Advantages of UV 5-24
5.3.2 Potential Operational and Simultaneous Compliance Issues Associated
with UV Disinfection 5-25
5.3.3 Recommendations for Gathering More Information 5-30
5.4 Chlorine Dioxide 5-32
5.4.1 Advantages of Chlorine Dioxide 5-32
5.4.2 Potential Operational and Simultaneous Compliance Issues Associated
with Chlorine Dioxide Use 5-34
5.4.3 Recommendations for Gathering More Information 5-39
5.5 Primary and Residual Disinfectant Use 5-41
5.5.1 Noteworthy Issues About Disinfectant Combinations 5-44
5.5.2 Recommendations for Gathering More Information 5-44
6. Making Compliance Decisions 6-1
6.1 Introduction 6-1
6.2 Issues to Consider When Making a Compliance Decision 6-2
6.3 Tools for Gathering Information 6-7
6.3.1 Water Quality Monitoring 6-7
6.3.2 Hydraulic and Water Quality Modeling for Distribution System 6-9
6.3.3 Desktop Evaluations 6-11
6.3.4 Bench-Scale Testing 6-12
6.3.5 Pilot Testing 6-15
6.3.6 Full-Scale Applications 6-16
6.3.7 Cost Estimation 6-18
6.3.8 Community Preferences 6-20
6.4 Basic Approach for Implementing Regulatory Compliance Projects 6-21
7. References 7-1
7.1 References Organized by Topic 7-1
7.1.1 General 7-1
7.1.2 Formation and Control of Chlorinated DBFs 7-9
7.1.3 Corrosion 7-10
7.1.4 Source Management 7-13
7.1.5 Distribution System Management 7-14
7.1.6 Problem Organisms in Water Treatment 7-16
7.1.7 Pre-sedimentation 7-17
7.1.8 Enhanced Coagulation and Enhanced Softening 7-17
7.1.9 GAC 7-19
7.1.10 Membranes 7-20
7.1.11 Riverbank Filtration 7-21
7.1.12 Chloramines 7-22
7.1.13 Ozone 7-25
7.1.14 Ultraviolet Light 7-27
7.1.15 Chlorine Dioxide 7-28
7.1.16 Tools for Gathering More Information 7-29
7.1.17 Chlorination 7-35
7.2 Comprehensive List of References 7-38
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Table of Contents (continued)
Appendices
Appendix A. Summary of Pertinent Drinking Water Regulations A-l
Appendix B. Case Studies B-l
Appendix C. Guidance for Evaluating Potential Impacts of Treatment Changes on
Distribution Systems C-l
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and
Copper Rule Compliance D-l
Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance E-l
Appendix F. Considerations for Systems Complying with the Ground Water Rule F-1
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List of Exhibits
Exhibit 1.1 Existing SDWA Regulations as of March, 2007 1-4
Exhibit 1.2 Organization of the Chapters 1-8
Exhibit 1.3 Organization of the Appendices 1-9
Exhibit 1.4 Treatment Technologies and Operational Changes Addressed in this
Guidance Manual 1-10
Exhibit 1.5 EPA Guidance Manuals under Development 1-14
Exhibit 2.1 Checklist for Identifying Key Operational and Simultaneous
Compliance Issues 2-2
Exhibit 2.2 Technology Alternatives and How They Potentially Affect Water Quality 2-3
Exhibit 2.3 Stage 2 DBPR and LT2ESWTR Compliance Technologies:
Summary of Benefits and Potential Conflicts 2-6
Exhibit 2.4 Potential Operational Issues for Different Treatment Modifications 2-12
Exhibit 2.5 Case Studies in this Guidance Manual and Issues they Address 2-13
Exhibit 2.6 Tools for Gathering System-Specific Information on Different Compliance
Techniques 2-16
Exhibit 3.1 Typical Chlorine Points of Application and Uses 3-21
Exhibit 3.2 Percent Reduction in DBF Formation by Moving Point of Chlorination 3-22
Exhibit 3.3 Effects of pH Changes on CT Required for 0.5-Log Inactivation of
Giardia lamblia 3-31
Exhibit 3.4 Impacts of pH on Formation of DBFs 3-31
Exhibit 3.5 Required CT for 0.5-Log Inactivation of Giardia lamblia by
Free Chlorine at pH 7.0 3-38
Exhibit 3.6 Effect of the Change of Water Quality Parameters Due to Enhanced
Softening on Corrosion of Piping System Materials 3-55
Exhibit 5.1 Comparison of Required CT (mg-min/L) values for Inactivation of
Viruses and Giardia by Free Chlorine and Monochloramine at
pH7and lOoC 5-8
Exhibit 5.2 Required CT values (mg-min/L) for Chemical Disinfectants at 10°C 5-14
Exhibit 5.3 Ratio of CT values for Inactivation of Viruses and Cryptosporidium at 10°C.... 5-27
Exhibit 5.4 Required CT Values for Inactivation of Microorganisms by Chlorine
Dioxide Compared with Other Chemical Disinfectants at 10°C and
pH 6-9 (in mg-min/L) 5-33
Exhibit 5.5 Effect of Temperature on the CT Required for Cryptosporidium Inactivation
by Chlorine Dioxide 5-36
Exhibit 5.6 Summary of Potential Benefits and Adverse Effects Associated with Different
Combinations of Primary and Residual Disinfectants 5-42
Exhibit 6.1 Issues to Consider When Deciding How to Comply with Stage 2 DBPR
and/or LT2ESWTR 6-3
Exhibit 6.2 Application of Information Gathering Tools at Various Project
Implementation Stages 6-22
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March 2007
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List of Abbreviations and Acronyms (continued)
List of Abbreviations and Acronyms
AOC
APHA
AMTA
As(III)
As(V)
AWWA
AwwaRF
BAT
BLS
BMPs
BDOC
C
CDPHE
CFE
CIS
CO2
CaCO3
CPE
CT
CTA
CWS
DBF
DBPR
DCWASA
DE
DO
DIC
DOC
OOP
EBCT
EPA
FBRR
GAC
GPM
GWR
GWUDI
H2C03
HCO3"
HAA
HAAS
assimilable organic carbon
American Public Health Association
American Membrane Technology Association
arsenite
arsenate
American Water Works Association
American Water Works Association Research Foundation
best available technology
below land surface
best management practices
biodegradable dissolved organic carbon
disinfectant concentration in mg/L (in CT calculations)
Colorado Department of Health and Environment
combined filter effluent
Customer Information System
carbon dioxide
calcium carbonate
comprehensive performance evaluation
disinfectant concentration x contact time, a measure of
disinfection performance
comprehensive technical assistance
community water system
disinfection byproduct
Disinfectants and Disinfection Byproducts Rule
Washington D.C. Water and Sewage Authority
diatomaceous earth
dissolved oxygen
dissolved inorganic carbon
dissolved organic carbon
demonstration of performance
empty bed contact time
U.S. Environmental Protection Agency
Filter Backwash Recycling Rule
granular activated carbon
gallons per minute
Ground Water Rule
ground water under the direct influence of surface water
carbonic acid
bicarbonate
haloacetic acid
the sum of five HAA species (monochloroacetic,
dichloroacetic, trichloroacetic, monobromoacetic, and
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For the Long Term 2 and Stage 2 DBF Rules
VI
March 2007
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List of Abbreviations and Acronyms (continued)
HACCP
HOC1
HPC
HRT
ICR
ISO
IESWTR
IFE
LCR
LRAA
LT IESWTR
LT2ESWTR
MCL
MCLG
M/DBP
MF
MOD
MIB
MRDL
MRDLG
MWCO
N.d.
ND
NF
NOM
NPDES
NTNCWS
NTU
OC1
OCCT
O&M
ORP
PAC
PAC1
POTW
PWS
RAA
RCAP
RCRA
RMP
RO
SDS
SCADA
SOC
SDWA
Stage 1 D/DBPR
Stage 2 D/DBPR
dibromoacetic acids)
Hazard Analysis and Critical Control Point
hypochlorous acid
heterotrophic plate count
hydraulic residence time
Information Collection Rule
International Organization for Standardization
Interim Enhanced Surface Water Treatment Rule
individual filter effluents
Lead and Copper Rule
locational running annual average
Long Term 1 Enhanced Surface Water Treatment Rule
Long Term 2 Enhanced Surface Water Treatment Rule
maximum contaminant level
maximum contaminant level goal
microbial disinfection byproducts
microfiltration
millions gallon per day
2-methylisoborneol
maximum residual disinfection level
maximum residual disinfection level goal
molecular weight cutoff
no date
non-detectable
nanofiltration
natural organic matter
National Pollutant Discharge Elimination System
non-transient non-community water system
nephelometric turbidity unit
hypochlorite ion
optimal corrosion control treatment
operations and maintenance
oxidation reduction potential
powder activated carbon
polyaluminum chloride
publicly owned treatment works
public water system
running annual average
Rural Community Assistance Partnership
Resource Conservation and Recovery Act
Risk Management Plan
reverse osmosis
simulated distribution system
Supervisory Control and Data Acquisition
synthetic organic chemicals
Safe Drinking Water Act
Stage 1 Disinfectants and Disinfection Byproducts Rule
Stage 2 Disinfectants and Disinfection Byproducts Rule
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
VII
March 2007
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List of Abbreviations and Acronyms (continued)
SUVA
SWTR
T
TCR
IDS
TENORM
THM
TTHM
TTHMFP
TOC
TOP
ISO
UF
UFC
UPS
UV
UVT
VOC
WEF
WFP
WTP
WWTP
specific ultraviolet absorbance
Surface Water Treatment Rule
contact time in minutes (in CT calculations)
Total Coliform Rule
total dissolved solids
technologically enhanced naturally occurring radioactive
materials
trihalomethane
total trihalomethane (sum of chloroform, BDCM, DBCM, and
bromoform)
total trihalomethane formation potential
total organic carbon
Texas Optimization Program
total system optimization
ultrafiltration
uniform formation conditions
universal power supply
ultraviolet light
ultraviolet light transmittance
volatile organic compound
Water Environment Foundation
water filtration plant
water treatment plant
wastewater treatment plant
Simultaneous Compliance Guidance Manual
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Vlll
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1 Introduction
The Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) and the Stage
2 Disinfectants and Disinfection Byproducts Rule (DBPR) were developed and promulgated
together to address risk trade-offs between two different types of contaminants: microbial
pathogens and disinfection byproducts. The U.S. Environmental Protection Agency (EPA)
recognizes that systems may encounter compliance issues with the Stage 2 DBPR when making
changes to comply with the LT2ESWTR, and vice versa. In addition to the challenges of
complying with the suite of microbial/disinfection byproduct (M/DBP) rules simultaneously, a
water system must also ensure that changes in treatment to comply with those rules do not
adversely affect compliance with other drinking water regulations.
This chapter answers the questions:
1.1 What is the purpose of this guidance manual?
1.2 What is "Simultaneous Compliance"?
1.3 Does this manual address compliance with environmental regulations other than
Safe Drinking Water Act regulations?
1.4 Who should use this guidance manual? How should it be used?
1.5 How is this manual organized?
1.6 Can I rely on this guidance manual alone to make compliance decisions?
1.7 Are there quick references I can use to screen for potential simultaneous
compliance problems?
1.8 Where can I get help achieving simultaneous compliance?
1.9 What additional resources are available?
1.1 What is the purpose of this guidance manual?
This manual addresses
simultaneous compliance issues
that may arise as systems make
treatment changes to comply
with the LT2ESWTR and/or the
Stage 2 DBPR.
The purpose of this guidance manual is to
help water systems and their regulators identify
and mitigate potential simultaneous compliance
issues that may arise when systems make changes
to comply with the LT2ESWTR and/or the Stage 2
DBPR. The manual lists possible ways that
simultaneous compliance issues could be
addressed. In addition, tools are recommended and
described to help determine if potential issues may
affect a given system.
Another key purpose of this manual is to provide a clearinghouse of information,
directing the reader to helpful resources. It would not be practical for one document to contain
comprehensive technical and operational information for all of the Stage 2 DBPR and
LT2ESWTR compliance treatment technologies. Each public water system (PWS) has different
Simultaneous Compliance Guidance Manual 1-1 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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1. Introduction
source water, existing treatment processes, distribution system materials, layout, storage,
operations, and other characteristics that should be evaluated and addressed by the system in
conjunction with the state and if necessary outside technical consultants, to ensure long-term
compliance. EPA has designed this manual to raise potential simultaneous compliance issues,
and directs readers to other references for more in-depth information.
After the draft version of this manual was released for public comment in September of
2006, the Ground Water Rule (GWR) was promulgated in November of 2006. Most
simultaneous compliance issues faced by systems using disinfection to comply with the GWR
are already covered in the main body of this manual. EPA has identified a few issues, however,
that may be unique, such as when ground water systems add disinfection for the first time.
These issues and recommendations for addressing them are included in a new appendix
(Appendix F).
1.2 What is "Simultaneous Compliance"?
For the purposes of this guidance manual, simultaneous compliance means compliance
with all existing Safe Drinking Water Act (SDWA) regulations, as summarized in Exhibit 1.1.
Two-page fact sheets for many of the regulations are included in Appendix A. While systems
may be concerned with issues pertaining to emerging contaminants, this guidance manual is not
designed to address these concerns and does not discuss these issues.
1.3 Does this manual address compliance with environmental regulations
other than SDWA regulations?
In addition to SDWA regulatory issues, systems should always weigh operational issues
and compliance with other environmental regulations when considering a treatment change.
While this document provides some discussion of non-SDWA regulations and other compliance
challenges (e.g. discharge permits, sludge disposal), readers should seek additional guidance and
other technical references for addressing these compliance issues.
1.4 Who should use this guidance manual? How should it be used?
This manual is for systems that
already know they need to make
a change in operations or
treatment.
This manual should be used by public
water systems that already know they need to
make a change to comply with the requirements
of the LT2ESTWR and/or the Stage 2 DBPR.
The manual is targeted to water system
managers, engineers, consultants, and regulators.
It assumes that readers have a technical
background and some familiarity with water treatment processes (for readers without this
background, see Section 1.8 for how to obtain technical assistance).
Simultaneous Compliance Guidance Manual 1-2 March 2007
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1. Introduction
This manual should be used as a technical resource as systems select a treatment
alternative or operational change. Example 1.1 shows how managers of a hypothetical system
could use this manual to help inform their decision-making about treatment changes to comply
with the LT2ESWTR. Example 1.2 shows how a regulator working with the same hypothetical
system could also use this guidance manual as a technical resource.
Before considering a treatment or operational change to achieve compliance with the
LT2ESWTR and/or Stage 2 DBPR, water systems should make sure their sources are well-
managed for both for quantity and quality and existing treatment processes are working well.
For surface water systems, treatment plant performance should be optimized for disinfectant
byproduct (DBF) precursor removal, filtered water turbidity should be well-controlled, and
disinfectants should be applied for sufficient time and at sufficient concentrations for inactivation
of microbial pathogens. All water systems should actively manage their distribution systems to
meet water demand and provide consistently good water quality. EPA encourages systems to
take advantage of existing voluntary programs in place including the Partnership for Safe Water,
Qualserve, and Areawide Optimization. Appendix E describes these and other programs that can
be used to achieve simultaneous compliance.
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1. Introduction
Exhibit 1.1 Existing SDWA Regulations as of March, 2007
Rule/Memo
Ground Water Rule (GWR)
Long Term 2 Enhanced Surface
Water Treatment Rule
(LT2ESWTR)
Stage 2 Disinfectants and
Disinfection Byproducts Rule
(Stage 2 DBPR)
Arsenic and Clarifications to
Compliance and New Source
Monitoring Rule
Lead and Copper Rule (LCR)
LCR Clarification of
Requirements for Collecting
Samples and Calculating
Compliance
Total Coliform Rule (TCR)
Stage 1 Disinfectants and
Disinfection Byproducts Rule
(Stage 1 D/DBPR)
Interim Enhanced Surface Water
Treatment Rule (IESWTR)
Long Term 1 Enhanced Surface
Water Treatment Rule
(LT IESWTR)
Filter Backwash Recycling Rule
(FBRR)
Surface Water Treatment Rule
(SWTR)
Date of
Promulgation
November
2006
January 2006
January 2006
January 2001
June 1991
November
2004
June 1989
December 1998
December 1998
January 2002
June 2001
June 1989
Contaminant of
Concern
Source Water
Microbial
Pathogens
Source Water
Microbial
Pathogens
Disinfection
Byproducts
Arsenic
Lead and Copper
Lead and Copper
Distribution
System Microbial
Pathogens
Disinfectants and
Disinfection
Byproducts
Source Water
Microbial
Pathogens
Source Water
Microbial
Pathogens
Filter Backwash
(Microbial
Pathogens)
Source Water
Microbial
Pathogens
Rule Summary
Information Available
from EPA
Fact Sheet, included in
Appendix A
Fact Sheet, included in
Appendix A
Fact Sheet, included in
Appendix A
Quick Reference Guide,
included in Appendix A
Quick Reference Guide,
Included in Appendix A
Fact Sheet, included in
Appendix A
Quick Reference Guide,
included in Appendix A
Quick Reference Guide,
included in Appendix A
Quick Reference Guide,
included in Appendix A
Quick Reference Guide,
included in Appendix A
Quick Reference Guide,
included in Appendix A
Summary information on
the web at
http : //www . epa. aov/safewa
ter/therule .html# Surface
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1. Introduction
Example 1.1 How this Manual can Help Water System Personnel Better Understand
Their Choices
System A is a community water system serving filtered surface water to 11,000 people. Based on
source water Cryptosporidium data the system has begun to collect, System A will likely be placed in
the second LT2ESWTR bin and therefore will need an additional 1.0 log Cryptosporidium removal or
inactivation. The system hired an engineer to conduct a feasibility study. The engineer
recommended three possible compliance options:
• Bank filtration
• Bag filters
• Ozone
Before discussing any of them with their state regulator or recommending any of them to their water
board, System A wanted more information on each technique. In addition to worrying about costs
and operational challenges, the staff is concerned that making a change to comply with LT2ESWTR
might put them out of compliance with another drinking water regulation.
System A picks up this Simultaneous Compliance Guidance Manual and
• Refers to Chapter 2 for summaries of the issues that pertain to these three treatment
alternatives.
• Reads Section 4.4 Other Microbial Removal Technologies in Chapter 4 for information
on simultaneous compliance issues associated with bank filtration and bag filters.
• Reads Section 5.2 Ozonation in Chapter 5 for information on simultaneous compliance
issues associated with ozone.
• Gets additional references about bank filtration, bag filters, and ozone from Chapter 7.
• Reviews Section 5.5 Primary and Residual Disinfectant Use in Chapter 5 to see what
issues might arise using the combination of ozone as primary disinfectant and free
chlorine as residual disinfectant.
• Based on their reading, System A want to know more about whether they might have
distribution system biofilm problems from switching to ozone. They refer to Appendix C
Guidelines for Evaluating Potential Impacts of Treatment Changes on Distribution
Systems and read the section on adding ozone and the section on installing ozone without
subsequent biological filtration.
• System A decides it would be beneficial to know how each of the treatment alternatives
could be evaluated more before installation. They read through Section 6.3 Tools for
Gathering Information and identify tools that may be helpful for evaluating the three
alternatives.
While they still have many questions for their engineer and have not yet chosen a treatment
technique, System A's managers feel more prepared to discuss the pros and cons of each alternative.
They have identified questions they would like answered before they take the next step.
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1. Introduction
Example 1.2 How This Manual Can Help Regulators Understand Potential
Simultaneous Compliance Issues
The state is scheduled to meet with System A to discuss the possibility of installing ozone treatment
to comply with the LT2ESWTR. The state's engineers are concerned that this change could
potentially make it difficult for System A to comply with other regulations. They're particularly
concerned with bacteriological regrowth in the distribution system.
They pick up this Simultaneous Compliance Guidance Manual and
• Read Section 5.2 Ozonation in Chapter 5 for information on simultaneous compliance
issues associated with ozone.
• Refer to Appendix C Guidelines for Evaluating Potential Impacts of Treatment Changes
on Distribution Systems and read the section on adding ozone and the section on
installing ozone without subsequent biological filtration.
• Read Case Study #10: Ozonation for an example of how one water system used ozone to
control microbial regrowth potential in the distribution system.
The regulators have many questions for System A, but are more prepared to discuss the prospect of
ozone as a way for the system to comply with their Cryptosporidium treatment requirement.
Simultaneous Compliance Guidance Manual 1-6 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
1. Introduction
1.5 How is this manual organized?
Exhibits 1.2 and 1.3 summarize the contents of each chapter and appendix in this
guidance manual.
Chapter 2 provides tables that summarize the potential benefits and conflicts of
LT2ESWTR and Stage 2 DBPR compliance technologies, operational issues that should be
considered, and tools that systems can use to evaluate a treatment technology's potential for
causing simultaneous compliance problems.
Chapters 3 through 5 of the manual are organized by treatment technology. This enables
the reader to refer to a particular section for a comprehensive discussion of simultaneous
compliance issues related to that treatment technique. For example, if the reader is considering
installing chloramines to achieve compliance with the Stage 2 DBPR, the reader should refer to
Section 5.1 for a discussion of pertinent simultaneous compliance issues that relate to using
chloramines. Exhibit 1.4 provides brief descriptions of the treatment technologies and
operational changes identified as compliance options in this guidance manual.
Within Chapters 3 through 5, each section on a treatment technique is organized as
follows:
• A summary of Advantages of the treatment technique;
• Potential Operational and Simultaneous Compliance Issues, including
recommendations for addressing each issue; and
• Recommendations for Gathering More Information, including suggestions for
additional monitoring, tools that are available for collecting additional system
information, and a short description of related case studies.
Chapter 6 identifies issues that should be considered before a change in treatment or
operations is made. It also describes tools available to help systems collect information that is
applicable and helpful for making their compliance decisions.
Chapter 7 provides a complete reference list, grouped by subject and also listed
alphabetically. Most of the subject headings in Chapter 7 correspond to specific treatment
technologies. Exceptions include technical references for DBF formation, technical references
for corrosion, and general water treatment references.
Simultaneous Compliance Guidance Manual 1-7 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
1. Introduction
Exhibit 1.2 Organization of the Chapters
Ch #..,
Is titled...
and has information on...
Quick Reference Materials for
Simultaneous Compliance
• A checklist to help systems quickly identify simultaneous
compliance issues
• Tables summarizing compliance, operational, and water quality
issues for each compliance technology
• Tables summarizing tools and pertinent case studies
Improving and Optimizing
Current Operations
Source Management
Distribution System Best Management Practices
Moving Point of Chlorination
Decreasing pH
Reducing Chlorine Dose Under Warm Water Conditions
Modifying Presedimentation Basin Operations
Enhanced Coagulation
Enhanced Softening
Installing New Total Organic
Carbon or Microbial Removal
Technologies
• Granular Activated Carbon
• Microfiltration/Ultrafiltration (MF/UF)
• Nanofiltration
• Other Microbial Removal Technologies
Alternative Disinfection
Strategies
• Chloramines
• Ozone
• Ultraviolet Light
• Chlorine Dioxide
Primary and Secondary (residual) Disinfectant Use
Making M/DBP Compliance
Decisions
Tools available for:
• Water Quality Monitoring
• Hydraulic and Water Quality Modeling for Distribution
Systems
• Desktop Evaluations
• Bench-Scale Testing
• Pilot Testing
• Full-Scale Applications
• Cost Estimation
• Community Preferences
References
Technical references grouped by subject and also listed
alphabetically
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
1-8
March 2007
-------
1. Introduction
Exhibit 1.3 Organization of the Appendices
Appendix.
is titled...
and has information on...
A
Summary of Pertinent
Drinking Water
Regulations
Summaries of major EPA drinking water regulations in the
form of 2-page fact sheets and quick reference guides.
B
Case Studies
Case studies illustrating simultaneous compliance challenges
that water systems have encountered when implementing
treatment techniques to help comply with one or more of the
M/DBP rules.
Guidelines for Evaluating
Potential Impacts of
Treatment Changes on
Distribution Systems
Summary of issues that may arise in the distribution system
as a result of changes made during treatment.
D
Tools for Evaluating
Impacts of Treatment
Changes on Lead and
Copper Rule Compliance
Tools that can be used to test impacts of a water quality
change on corrosion, which can result in violations of the
LCR. References for further information are also included.
Innovative Management
Tools for Achieving
Simultaneous Compliance
Existing and developing programs that can help water
systems comply with regulations and produce consistently
high quality water. Contains descriptions of performance-
driven optimization programs and integrated management
approaches that consider treatment processes and operating
practices throughout the entire water system.
Considerations for
Systems Complying with
the Ground Water Rule
Considers unique challenges that may emerge when systems
make treatment or source changes to comply with the GWR.
Contains a brief overview of the GWR and a discussion of
corrective actions that could create simultaneous compliance
issues.
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
1-9
March 2007
-------
1. Introduction
Exhibit 1.4 Treatment Technologies and Operational Changes Addressed in this
Guidance Manual1
Technology or Operational Change
Source Management (sec. 3.1)
Distribution System Best Management
Practices (sec. 3. 2)
Moving Point of Chlorination (sec. 3. 3)
Modifying pH during Chlorination
(sec.3.4)
Reducing Chlorine Dose under Warm
Water Conditions (sec.3.5)
Modifying Presedimentation Basin
Operations (sec. 3. 6)
Enhanced Coagulation (sec. 3. 7)
Enhanced Softening (sec.3.8)
Granular Activated Carbon (sec.4.1)
Microfiltration/Ultrafiltration
(MF/UF) (sec.4.2)
Nanofiltration (sec.4.3)
Improved Filtration Performance
(sec.4.4)
Slow Sand Filtration (sec.4.4)
Diatomaceous Earth Filtration
(sec.4.4)
River Bank Filtration (sec.4.4)
Bag Filtration (sec.4.4)
Cartridge Filtration (sec.4.4)
Chloramines (sec. 5.1)
Ozone (sec. 5.2)
Ultraviolet Light (sec.5.3)
Chlorine Dioxide (sec. 5. 4)
Description
Management techniques that manipulate a source(s) to provide
water with the lowest concentration of DBF precursors or
pathogens possible.
Management techniques designed to maintain the integrity of the
distribution system and limit or reduce microbial growth, DBFs,
or incursion into the distribution system.
Moving Chlorination further downstream in the plant to a point
where more DBF precursor removal has taken place.
Lowering the pH of the water during the Chlorination process.
Lowering the chlorine dose under warmer water temperature
conditions.
Changing operation of presedimentation basins to achieve more
removal of pathogens by adding coagulant or increasing
residence time.
Achieving more organic carbon removal by using higher
coagulant doses under lower pH conditions.
Achieving more organic carbon removal by adding coagulant and
increasing the lime dose to raise the pH.
Filtering water through a bed of granular activated carbon either
by itself or as part of a granular filter.
A low pressure membrane process used to remove microbes and
some organic carbon.
A pressure membrane process used to remove particles and some
dissolved organic matter. Nanofiltration uses membranes with
smaller pores than MF/UF.
Changes in the operation of filters to lower the effluent turbidity
tobelowO.lONTU.
A gravity filtration process using sand as the filtration medium.
Filtration through a layer of diatomaceous earth placed on a
permeable membrane. It can be a pressure or vacuum process.
A filtration process that uses vertical or horizontal wells drilled
near a river bank to filter the water through the river bank
material.
A filtration process that filters water through a fabric material.
A pressure filtration process that filters water through a
membrane cartridge.
Adding chloramines to the water to achieve disinfection.
Chloramines are formed by adding chlorine and ammonia
together in water.
Adding ozone to water to achieve disinfection. Ozone is
generated on site using oxygen.
Passing light from ultraviolet lamps through the water to achieve
disinfection.
Adding chlorine dioxide to water to achieve disinfection.
Chlorine dioxide is generated on site.
These technologies and operational changes are not necessarily appropriate for every system; rather they
are approaches that systems may opt to pursue based on a system-specific analysis.
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
1-10
March 2007
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1. Introduction
1.6 Can I rely on this guidance manual alone to make compliance
decisions?
No, this guidance manual alone is not intended to provide comprehensive technical
guidance for systems making treatment modifications. Instead, systems are encouraged to use
this manual as a technical resource to identify potential issues and possible solutions to those
issues. Chapter 6 describes the potential tools for assessing compliance choices. Chapter 7
provides an extensive reference list, grouped by subject matter, which systems can use to obtain
more information as they plan treatment modifications. Systems should take into account source
water characteristics, existing treatment processes, distribution system issues, available
resources, and other system-specific information in determining the best compliance approach.
This guidance manual is just one of many guidance manuals EPA has developed or is
developing to help systems comply with the rules under the Safe Drinking Water Act. EPA
recommends systems first visit EPA's websites for the Stage 2 DBPR
(http://www.epa.gov/OGWDW/disinfection/stage2) and the LT2ESWTR
(http://www.epa.gov/OGWDW/disinfection/lt2). These websites have a wealth of technical
links to assist systems with identifying their compliance requirements and options. Readers can
also visit http://www.epa.gov/safewater for general regulatory information.
In addition, each state may have its own rules and regulations pertaining to treatment
modifications. For example, many states have review and approval procedures that must be
followed before making any compliance decisions. Systems should contact their state for further
information.
1.7 Are there quick references I can use to screen for potential
simultaneous compliance problems?
Yes, Exhibit 2.1 in Chapter 2 is a one-page checklist that systems can use to quickly
identify key potential operational and simultaneous compliance issues. This checklist could be
particularly helpful for small systems or systems with limited resources. Chapter 2 also provides
the following summary tables to help systems screen for potential issues:
• Exhibit 2.2 Technology Alternatives and How They Potentially Affect Water Quality
• Exhibit 2.3 Stage 2 DBPR and LT2ESWTR Compliance Technologies: Summary of
Benefits and Potential Conflicts
• Exhibit 2.4 Potential Operational Issues for Different Treatment Modifications
• Exhibit 2.5 Case Studies in this Guidance Manual and Issues They Address
• Exhibit 2.6 Tools for Gathering System-Specific Information on Different
Compliance Techniques
Simultaneous Compliance Guidance Manual 1-11 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
1. Introduction
1.8 Where can I get help achieving simultaneous compliance?
Some water system engineers and managers may need assistance understanding the more
technically complex portions of this guidance manual. Others may need assistance weighing
which of the potential issues are likely to occur in their system. EPA encourages these readers to
seek help from their regulators, technical assistance providers, or consulting engineers. In
addition, small water system managers are encouraged to seek help from their state, local Rural
Water Association circuit riders, or the Rural Community Assistance Partnership (RCAP). EPA
has also published small entity compliance guides for both the LT2ESWTR (USEPA 2007a) and
the Stage 2 DBPR (USEPA 2007b).
Troubleshooting Guides
Some water systems may encounter problems with their treatment performance or finished water
quality as they modify treatment to comply with the new regulations. Here are a few troubleshooting
guides that can help those systems (and systems in general) identify and address treatment
problems:
Bevery, R.P. 2005. Filter Troubleshooting and Design Handbook. 425 pp. Denver: AWWA.
Lauer, W.C. 2004. Water Quality Complaint Investigator's Field Guide. 102pp. Denver: AWWA.
Logsdon, G.S., A.F. Hess, M.J. Chipps, and A.J. Rachwal. 2002. Filter Maintenance and Operations
Guidance Manual. AwwaRF Report 90908. Project #2511. Denver: AwwaRF.
Tillman, G.M. 1996. Water Treatment: Troubleshooting and Problem Solving. 176 pp. Boca Raton:
CRC Press LLC.
1.9 What additional resources are available?
Chapter 7 contains a comprehensive list of references, grouped by subject. EPA
references are discussed below. In addition to these many references, the American Water
Works Association Research Foundation (AwwaRF) is currently developing a decision tool to
help utilities develop simultaneous compliance strategies (Project #3115). Publication of this
tool is expected in 2008.
The 1999 M-DBP Simultaneous Compliance Guidance Manual
The Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance
Manual (USEPA 1999f) was published in conjunction with the promulgation of the Stage 1
D/DBPR and the Interim Enhanced Surface Water Treatment Rule (IESWTR). The 1999
manual is organized by regulation, describing how compliance with the Stage 1 D/DBPR or
IESWTR might affect compliance with another regulation, focusing on one regulation at a time.
Some readers may be more comfortable with that layout.
Since several issues discussed in the 1999 manual continue to be issues that present
challenges to systems trying to comply with the LT2ESWTR and Stage 2 DBPR, readers could
also refer to the 1999 manual for guidance. The 2007 Simultaneous Compliance Guidance
Manual, however, provides more up-to-date findings and references. It also focuses more
Simultaneous Compliance Guidance Manual 1-12 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
1. Introduction
specifically on those technologies that have been identified as treatment solutions for complying
with the requirements of the LT2ESWTR and the Stage 2 DBPR.
Additional EPA References
In conjunction with promulgation of the IESWTR, Stage 1 D/DBPR, Long Term 1
Enhanced Surface Water Treatment Rule (LTIESWTR), LT2ESWTR, and the Stage 2 DBPR,
EPA has published several guidance manuals that may assist PWSs in resolving potential
conflicts. Complete references for these guidance manuals are provided in Chapter 7. These
references include the following:
• Handbook: Optimizing Water Treatment Plant Performance Using the Composite
Correction Program (USEPA 1998a)
• Disinfection Profiling and Benchmarking Guidance Manual (USEPA 1999a)
• Alternative Disinfectants and Oxidants Guidance Manual (USEPA 1999b)
• Uncovered Finished Water Reservoirs Guidance Manual (USEPA 1999c)
• Guidance Manual for Compliance with the Interim Enhanced Surface Water
Treatment Rule: Turbidity Provisions (USEPA 1999d)
• Unfiltered Water Supply Systems Guidance Manual (USEPA 1999e)
• Guidance Manual for Conducting Sanitary Surveys of Public Water Systems; Surface
Water and Ground Water Under the Direct Influence (GWUDI) (USEPA 1999g)
• Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual
(USEPA 1999h)
• Implementation Guidance for the Stage 1 Disinfectants/Disinfection Byproducts Rule
(USEPA 200la)
• Low Pressure Membrane Filtration for Pathogen Removal: Application,
Implementation, and Regulatory Issues (USEPA 2001h)
• Controlling Disinfection By-Products andMicrobial Contaminants in Drinking Water
(USEPA 200 Ic)
• Ultraviolet Disinfection Guidance Manual for the Final Long Term 2 Enhanced
Surface Water Treatment Rule (USEPA 2006b)
• Membrane Filtration Guidance Manual (USEPA 2005b)
• Long Term 1 Enhanced Surface Water Treatment Rule Turbidity Provisions
Technical Guidance Manual (USEPA 2004h)
Simultaneous Compliance Guidance Manual 1-13 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
1. Introduction
• Complying with the Long Term 2 Enhanced Surface Water Treatment Rule: Small
Entity Compliance Guide (USEPA 2007a;
• Complying with the Stage 2 Disinfectants and Disinfection Byproduct Rule: Small
Entity Compliance Guide (USEPA 2007b;
Several additional guidance manuals are under development and will be published to help
water systems comply with the requirements of the Stage 2 DBPR, LT2ESWTR and the Ground
Water Rule. Information on these manuals is provided in Exhibit 1.5.
Exhibit 1.5 EPA Guidance Manuals under Development
Rule
LT2ESWTR
Stage 2 DBPR
GWR
Guidance Manual
Microbial Toolbox Guidance Manual
LT2ESWTR Implementation Guidance
Consecutive Systems Guidance Manual for
the Stage 2 DBPR
Operational Evaluation Guidance Manual
Stage 2 DBPR Implementation Guidance
Consecutive Systems Guidance Manual for
the GWR
Source Water Monitoring Guidance Manual
Source Water Assessment Guidance Manual
Corrective Actions Guidance Manual
Sanitary Survey Guidance Manual
Complying with the GWR: Small Entity
Compliance Guide
GWR Implementation Guidance
Weblink for Updates
http ://www. epa. sov/safewa
ter/disinfection/lt2/complia
nee, html
http ://www. epa. sov/safewa
ter/di sinfection/stage2/com
pliance.html
http ://www. epa. sov/safewa
ter/disinfection/gwr/compli
ancehelp.html
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
1-14
March 2007
-------
2 Quick Reference Materials
for Simultaneous Compliance
This Chapter provides matrices that can be used as screening tools by systems and states
to quickly identify potential simultaneous compliance issues, while the later chapters provide a
detailed discussion of these issues.
• Exhibit 2.1 (page 2-2) is a checklist that can be used to quickly identify potential
operational and simultaneous compliance issues. It may be particularly useful for
small systems or systems with limited resources.
• Exhibit 2.2 (starting on page 2-3) provides a summary of how different compliance
technologies may affect water quality. For example, while switching from chlorine
to UV will increase inactivation of Cryptosporidium, it may decrease inactivation for
viruses. Note that the changes shown in this exhibit may or may not occur at a
specific water system; they are listed so that systems and states will be aware of them
and the possibility that they may be an issue.
• Exhibit 2.3 (starting on page 2-6) summarizes simultaneous compliance issues for
individual LT2ESWTR and Stage 2 DBPR compliance technologies. For some
treatment strategies listed, no significant impact on drinking water regulations is
anticipated. Systems may, however, encounter other challenges, such as an increase
in waste residuals or a reduction in the quantity of treated water that can be produced.
• Exhibit 2.4 (starting on page 2-12) identifies potential operational issues for
individual LT2ESWTR and Stage 2 DBPR compliance technologies. Note that the
operational issues shown in this exhibit may or may not occur at a specific water
system; they are listed so that systems and states will be aware of them and the
possibility that they may be an issue.
• Exhibit 2.5 (starting on page 2-13) provides summary information on each of the case
studies in Appendix B. The case studies give real-world examples of how systems
have dealt with simultaneous compliance issues with past regulations and in
anticipation of the Stage 2 DBPR and LT2ESWTR.
• Exhibit 2.6 (page 2-16) lists tools that can be used to gather more information on how
a system may be affected by a treatment change.
Simultaneous Compliance Guidance Manual 2-1 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
2. Quick Reference Materials for Simultaneous Compliance
If you are considering a treatment modification or a new treatment to meet the LT2ESWTR or Stage 2 DBPR, this checklist
can help you see if you might have problems complying with other drinking water regulations. If you answer "yes" to any of these
questions, go to the section in Chapter 3, 4, or 5 that addresses your treatment change. There you will find a list of potential
simultaneous compliance issues, suggestions for how to address them, and other helpful information. If you are not sure how to
answer any of these questions or need help understanding the water quality impacts of a treatment change, consult your state regulator,
technical assistance provider, or a consulting engineer.
Exhibit 2.1 Checklist for Identifying Key Operational and Simultaneous Compliance Issues
Yes No
Will you be getting less CT (measured as log inactivation) for any regulated microorganism (i.e. viruses, Giardia, or
^ Ll Cryptosporidium) as a result of the treatment change? If you answered "yes" and are a surface water system, you
must conduct disinfection benchmarking and profiling. If you are a ground water system required to meet 4-log
inactivation, you must continue to meet 4-log inactivation.
rj rj Will the treatment change cause an increase (seasonal or permanent) in organic carbon at any point before
disinfectant addition? If yes, you could potentially have problems complying with the Stage 1 DBPR, the Stage 2
DBPR, or the TCR.
fj fj Will the treatment change thepH and/or alkalinity of your finished water"! If yes, your finished water could be more
corrosive and you could have problems complying with the LCR.
rj rj Will you be using a different residual disinfectant or a different concentration of residual disinfectant? Disinfectant
residual changes can impact TCR and LCR compliance.
rj rj Will the treatment change affect the quality of water being filtered? A change in coagulation or pre-disinfection could
affect filter performance and compliance with the LT1ESWTR or IESWTR.
i-i 1-1 Will the treatment change result in higher or lower concentrations of inorganics, such as manganese, iron,
aluminum, sulfate, chloride, or sodium in your finished water? If yes, your water could become more corrosive and
you could have problems complying with the LCR. You could also have aesthetic problems.
D D Will the treatment change cause an increase in production of waste residuals (e.g., enhanced coagulation could
cause your system to produce more sludge)? This will not typically cause any rule violations but may require
increased land disposal area, and increased residual production can present operational challenges for your system.
Simultaneous Compliance Guidance Manual 2-2 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
2. Quick Reference Materials for Simultaneous Compliance
Exhibit 2.2 Technology Alternatives and How They Potentially Affect Water Quality
Source
Management2
Distribution
System BMPs
Moving the Point
of Chlorination
Downstream
Decreasing pH
Reducing
Chlorine Dose
Under Warmer
Water Conditions
Presedimentation
Enhanced
Coagulation
Softening/
Enhanced
Softening
Inactivation
of microbial
pathogens
May
decrease if
colder water
is used
May
decrease
Increase
(for chlorine
only)
may
decrease
may
increase
may
increase,
may
decrease due
to high pH
pH
may
increase or
decrease
decrease
may
increase or
decrease
decrease
increase
alkalinity
may
increase
or
decrease
may
decrease
may
decrease
may
increase
disinfectant
residual1
may
increase
may
increase or
decrease
may
decrease
iron or
manganese
may
increase
may
increase
may
decrease
manganese
may
increase
may
decrease
turbidity
may
increase if
flushing
not done
properly
may
decrease
may
increase
or
decrease
may
decrease
NOM
may
decrease
may
decrease
decrease
may
decrease
DBFs
may
decrease
TTHM may
decrease;
HAAS may
decrease or
increase
decrease
TTHM may
decrease,
HAAS may
increase
decrease
may
decrease
decrease
HAAS may
decrease,
TTHM may
increase
corrosivity
may
increase or
decrease
may
decrease
may
increase
may
increase
concrete
corrosion
may
increase
AOC
taste and
odor
may
increase
may
increase
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
2-3
March 2007
-------
2. Quick Reference Materials for Simultaneous Compliance
GAC
Microfiltration/
Ultrafiltration
Nanofiltration
Bank Filtration
Bag Filtration
Cartridge
Filtration
Second Stage
Filtration
Slow Sand
Filtration
DE Filtration
Improved Filter
Performance
Chloramines3
Ozone3
UV Disinfection3
Inactivation
of microbial
pathogens
decrease
increase for
protozoa
UV dose is
low for
protozoa,
need higher
dose for
viruses
pH
may
decrease
alkalinity
may
decrease
disinfectant
residual1
may
increase
iron or
manganese
may
decrease
decrease
may
increase
may
decrease
may
decrease
may
decrease
may
decrease
may
decrease
may
decrease
turbidity
may
increase
due to
GAC fines
decrease
decrease
may
decrease
may
decrease
decrease
may
decrease
may
decrease
decrease
NOM
decrease
may
decrease
may
decrease
may
decrease
may
decrease
DBFs
decrease
may
decrease
decrease
may
decrease
may
decrease
may
decrease
TTHMand
HAAS will
decrease
may
decrease, but
increase in
bromate
decrease
corrosivity
increase
may
increase or
decrease
may
increase or
decrease
AOC
may
decrease if
GAC is
biologically
active
may
decrease
may
decrease
taste and
odor
decrease
may
increase or
decrease
may
increase or
decrease
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
2-4
March 2007
-------
2. Quick Reference Materials for Simultaneous Compliance
Chlorine Dioxide3
Inactivation
of microbial
pathogens
increase for
protozoa,
decrease for
viruses
pH
alkalinity
disinfectant
residual1
iron or
manganese
may
decrease if
followed
by filtration
turbidity
NOM
DBFs
TTHMand
HAA5
decrease,
chlorite will
be formed
corrosivity
AOC
taste and
odor
may
increase or
decrease
Refers to the disinfectant residual in distribution system water.
For the purpose of this guidance, source management refers to techniques water systems can use to manipulate their water sources to comply
with Stage 2 DBPR or LT2ESWTR regulations. In this context, source management does not refer to source water protection or other long-term
watershed efforts to improve water quality. The source management techniques discussed in this section are operational changes made by
water systems to use the source with the least amount of natural organic matter (NOM), or selecting a blend of sources to try to achieve the
most effective treatment for organics and turbidity removal. Source management strategies can affect raw water quality or they can affect
finished water quality directly (e.g., blending or alternating sources).
Water quality changes for alternative disinfectants are compared to conditions when free chlorine is used.
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
2-5
March 2007
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2. Quick Reference Materials for Simultaneous Compliance
Exhibit 2.3 Stage 2 DBPR and LT2ESWTR Compliance Technologies:
Summary of Benefits and Potential Conflicts
Used for Compliance
System witn
Modification /
Compliance
Technology *£** LT2ESWTR
Source X X
Management
Distribution X
System BMPs
Moving the Point X
of Chlorination
Downstream
Potential Benefits
• may reduce DBF precursors
• may reduce disinfectant demand
• can improve treatability of raw water
for turbidity and/or DBF precursor
removal
• may reduce pathogen and particle
loading
• targets specific problem areas
• can improve microbial control
• can reduce corrosion
• can reduce nitrification
• improves chlorine residual
maintenance
• reduces DBF concentrations
• reduces amount of disinfectant used
• can facilitate monthly total organic
Potential Issues
Description
• water temperature change may affect CT and
coagulation/flocculation
• may introduce new contaminants (e.g. iron,
manganese, sulfide)
• raw water pH change can adversely affect water
treatment and/or corrosion control
• may increase coagulant demand
• may increase disinfectant demand
• change in aesthetic quality may generate
customer complaints
• can stir up sediments
• issues with disposal of chlorinated water
• lining materials may leach into water
• less storage available for emergencies
• increased waterless
• May impact ability to meet CT requirements
• increases chances of filter fouling
• may reduce Asiatic clam or zebra mussel
SDWA
Rule(s) of
Concern
SWTR, Stage
1 DBPR,
Stage 2
DBPR,
IESWTR,
LT1ESWTR,
LCR.
TCR, Stage 1
DBPR, Stage
2 DBPR.
IESWTR,
LT1ESWTR,
LT2ESWTR,
Where It's
Discussed in
More Detail
Section 3.1
Section 3. 2
Section 3. 3
carbon (TOC) source water
monitoring
control
provides less effective treatment for iron or
manganese
may limit coagulation and filtration
effectiveness
may need to increase disinfectant dosage, which
could produce more DBFs
Stage 1
DBPR.
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
2-6
March 2007
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2. Quick Reference Materials for Simultaneous Compliance
„ ^ Used for Compliance
Modification/ with
Compliance § 2
Technology DBpR LT2ESWTR
Decreasing pH X
Reducing X
Chlorine Dose
under Warm
Water
Conditions
Presedimentation X
Enhanced X
Coagulation
Potential Benefits
• same inactivation can be achieved
with lower disinfectant dose or
shorter free chlorine contact time
• lower pH may reduce some DBFs
• Comparable pathogen inactivation
with less chlorine
• Reduction in TTHM and HAAS
Formation
• removes Cryptosporidium
• can remove DBF precursors
• reduced solids loading and enhanced
stability of water
• may improve disinfection
effectiveness
• can reduce bromate formation by
Potential Issues
Description
• may increase HAAS
• can adversely affect treatment plant equipment
• may impact settling and sludge dewatering
• can cause corrosion problems
• may be difficult to maintain a residual
• Higher disinfectant residual needed for
addressing seasonal pathogens
• Distribution system impacts if finished water
chlorine concentration is decreased
• algal growth in basins can increase DBF
precursors
• removal of solids difficult
• may adversely impact finished water turbidity
• lower pH can cause corrosion problems
• may see increased inorganics concentrations in
Rule(s) of
Concern
Stage 1
IESWTR,
LTIESWTR,
LCR.
IESWTR,
LTIESWTR,
TCR, SWTR.
Stage 1
DBPR, Stage
2 DBPR.
IESWTR,
LTIESWTR,
LCR, FBRR.
Where It's
Discussed in
More Detail
Section 3. 4
Section 3. 5
Section 3. 6
Section 3. 7
reducing pH
can reduce DBF formation
can enhance arsenic and radionuclide
removal
finished water
issues with disposal of residuals
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
2-7
March 2007
-------
2. Quick Reference Materials for Simultaneous Compliance
System
Modification /
Compliance
Technology
Used for Compliance
with
Potential Issues
Potential Benefits
Stage 2
DBPR
LT2ESWTR
Description
Rule(s) of
Concern
Where It's
Discussed in
More Detail
Softening/
Enhanced
Softening
X
X
Granular
Activated
Carbon (GAC)
X
X
Microfiltration/
Ultrafiltration
Nanofiltration
Watershed
Control Program
X
X
X
X
X
• removes DBF precursors
• two stage plants can achieve
Cryptosporidium removal credit
• lower corrosion impacts
removes DBF precursors
can remove taste and odor
compounds
if used as secondary filter, can be
used to receive Cryptosporidium
removal credit
removes AOC after ozone when used
as biological filter
removes bacteria and protozoa
can lower DBFs by allowing lower
disinfectant doses
can remove arsenic
removes microbial pathogens
including viruses
can remove DBF precursors
removes arsenic
removes microbial pathogens
reduces DBF precursor loading
reduces chemical contamination
options for disinfection are limited
may increase scaling in treatment plant and
distribution system piping
higher TTHM formation at high pH (may be
offset by lower precursors)
pH adjustment may be needed for distribution
system and for disinfection effectiveness
increased sludge volume and change in sludge
characteristics
may release previously adsorbed compounds
bacteria can be released
fines can foul downstream processes at startup
can limit the ability to pre-chlorinate
chlorate can be formed when GAC comes into
contact with chlorine dioxide
ammonia added before GAC may increase
nitrification
may have increased loss of process water
can be fouled by organics and minerals
additional training required
can increase corrosiveness of water
issues with reject stream
can be fouled by organics and minerals
additional training required
none known
SWTR,
IESWTR,
LT1ESWTR,
LT2ESWTR,
Stage 1
DBPR.
TCR,
IESWTR,
LT1ESWTR.
Section 3.8
Section 4.1
SWTR.
Section 4.2
SWTRLCR. Section 4.3
None known Not
discussed
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
2-8
March 2007
-------
2. Quick Reference Materials for Simultaneous Compliance
System
Modification /
Compliance
Technology
Bank Filtration
Bag Filtration
Cartridge
Filtration
Second Stage
Filtration
Slow Sand
Filtration
Diatomaceous
Earth (DE)
Filtration
Improved Filter
Performance
Used for Compliance
with
Potential Benefits
DBPR LT2ESWTR
X • removes microbial pathogens
• decreases turbidity
• decreases DBF precursors
• relative ease of use
X • removes microbial pathogens
• relative ease of use
X • removes microbial pathogens
• relative ease of use
X X • reduces paniculate matter
• reduces DBF precursors
• removes microbial pathogens
• reduces assimilable organic carbon
(AOC)
X • removes microbial pathogens
• may reduce DBF precursors
X • removes microbial pathogens
X • removes microbial pathogens
• reduces chemical contaminants
Potential Issues
Description
• hydraulic issues
• iron/manganese problems
• clogging
• hydraulic issues
• filter fouling
• hydraulic issues
• disposal issues
• filter fouling
• hydraulic issues
• increased residuals
• hydraulic issues
• hydraulic issues
• increased residuals
• disposal issues
T> i / -> f Where It s
Rule(s) 01 „. , .
^ Discussed in
Concern ,„ __ ^ .,
More Detail
None known Section 4.4
None known Section 4.4
None known Section 4.4
None known Section 4.4
None known Section 4.4
None known Section 4.4
None known Section 4.4
improves aesthetic quality
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
2-9
March 2007
-------
2. Quick Reference Materials for Simultaneous Compliance
System
Modification /
Compliance
Technology
Chloramines
Used for Compliance
with
Potential Benefits
DBPR LT2ESWTR
X • reduce DBFs
• may improve biofilm control
• may increase ability to maintain
disinfectant residual throughout
distribution system
• may reduce occurrence ofLegionella
in hot water systems
Potential Issues
Description
• nitrification may occur in distribution system
• may cause corrosion problems with some
materials
• potential taste and odor problems if improper
ratio is used
• weaker disinfectant
• can be difficult to blend with chlorinated
Rule(s) of
Concern
TCR,
IESWTR,
SWTR, LCR.
Where It's
Discussed in
More Detail
Section 5.1
Ozone
X
Ultraviolet (UV)
Disinfection
X
X • inactivates Cryptosporidium and
Giardia
• does not form TTHM or HAAS
• effective pre-oxidant
• increases UV transmittance of water
• disinfection not pH dependent
• can oxidize taste and odor
compounds
• may aid coagulation if fed before
coagulant addition point
X • inactivates Cryptosporidium and
Giardia
• does not produce regulated DBFs
• effectiveness not pH or temperature
dependent
sources
ozone and GAC can lead to faster residual decay
must remove for dialysis patients, fish owners
and industrial users.
may form bromate
forms smaller organic compounds
does not provide a residual in the distribution
system
may increase dissolved oxygen in the water
can form taste and odor compounds
can cause corrosion to materials exposed to gas
ozone bubbles can hinder filter performance if
not operated properly
switching to ozone and biofiltration can cause
the release of manganese from filters
requires additional training
much higher doses needed to inactivate viruses
does not provide a residual
substances in water can interfere with UV
disinfection
potential for lamp breakage
power quality problems can cause loss of
disinfection
requires additional training
Stage 1
DBPR,
TCR, SWTR,
LCR,
IESWTR,
LT1ESWTR.
Section 5.2
SWTR,
IESWTR,
LT1ESWTR.
Section 5.3
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
2-10
March 2007
-------
2. Quick Reference Materials for Simultaneous Compliance
System
Modification /
Compliance
Technology
Used for Compliance
with
DBPR LT2ESWTR
Potential Issues
Potential Benefits
Description
Rule(s) of
Concern
Where It's
Discussed in
More Detail
Chlorine Dioxide
X
X • achieves some Cryptosporidium
inactivation
• less TTHM and HAAS formation
than with chlorine
• oxidizes iron and manganese
• disinfection not pH dependent
• chlorite residual may inhibit growth
of nitrifying bacteria in the
distribution system (benefit when
using in combination with
chloramines)
forms chlorite which may be a concern for MCL
compliance
reduced effectiveness at low temperatures
chlorine dioxide Maximum Residual
Disinfectant Level (MRDL) limits application
dose
can form brominated DBFs
degrades under UV light
residual dissipates quickly
potential odor problems
requires additional training and safety concerns
Stage 1
DBPR,
SWTR,
IESWTR,
LT1ESWTR.
Section 5.4
Brief descriptions of the treatment alternatives discussed here and later in this guidance manual are provided in Exhibit 1.4.
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
2-11
March 2007
-------
2. Quick Reference Materials for Simultaneous Compliance
Exhibit 2.4 Potential Operational Issues for Different Treatment Modifications
• i ; ' " * ' ' ' ' ,' «, ' '»i-' ;
Treatment Modification
Source Management
Distribution System BMPs
Moving Point of Chlorination Downstream
Decreasing pH
Decreasing Chlorine Dose Under Warm Water Conditions
Presedimentation
Enhanced Coagulation
Softening/Enhanced Softening
Granular Activated Carbon
Microfiltration/Ultrafiltration
Nanofiltration
Bank Filtration
-^ to
g ""
§ •§
1 fl to u
C3 1} C3
E 3 *5
J^t r t/} 0 W >-.
L^, *"^ ^^ CO
C^ ) J^* tO (j
g ^H Q HH O
.2 *9 to S o '^
O ^ '^ a ^ o
^ & a T3 t/3 'C
^ B 'tj 'to
-------
2. Quick Reference Materials for Simultaneous Compliance
Exhibit 2.5 Case Studies in this Guidance Manual and Issues they Address
Case
Study
No.
1
2
o
J
4
5
6
Treatment/Issue
Addressed
Improving and
Optimizing Current
Operations
Decreasing pH
Presedimentation
Switching
Coagulants
Enhanced
Coagulation -
Problems with
Copper Pitting
Enhanced
Coagulation -
Managing
Radioactive
Residuals
Utility Name
Owenton Water
Works and Kentucky
American TriVillage
Public Utility District
#1
Kansas City Water
Services
Hillsborough River
Water Treatment
Plant
Washington
Suburban Sanitary
Commission
Allen Water
Filtration Plant
Case Study
Location
Owenton, Kentucky
Skagit County,
Washington
Kansas City, Missouri
Tampa, Florida
Montgomery and
Prince Georges
County, Maryland
Englewood, Colorado
Population
Served
<10,000
70,000
>600,000
>450,000
1,600,000
48,000
Average
Annual
Treatment
Plant (MGD)
Production
1
12
240
100
167
8.5
Source
Water
Surface Water
(reservoir)
Surface Water
(reservoir)
Surface Water
(river, ground
water under
the direct
influence of
surface water)
Surface Water
(river)
Surface Water
(rivers)
Surface Water
(river, creek,
diversions)
Page
B-5
B-ll
B-19
B-23
B-29
B-33
Section
Where It is
Referenced
in the
Manual
3.3
3.4
3.6
3.7
3.7
3.7
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
2-13
March 2007
-------
2. Quick Reference Materials for Simultaneous Compliance
Case
Study
No.
7
8
9
10
11
12
13
Treatment/Issue
Addressed
GACforTOC
Removal
Nanofiltration
Membrane
Technology for TOC
Removal
Modifying
Chloramination
Practices to Address
Nitrification Issues
Ozonation
Ozonation and
Biological Filtration
UV Disinfection
Chlorine Dioxide for
Primary Disinfection
and Chloramines for
Secondary
Disinfection
Utility Name
Higginsville Water
Treatment Plant
PBCWUD Water
Treatment Plant #9
Ann Arbor Utilities
Ann Arbor Utilities
Sweeney Water
Treatment Plant
Poughkeepsie Water
Treatment Facility
Gulf Coast Water
Authority
Case Study
Location
Higginsville, Missouri
West Palm Beach,
Florida
Ann Arbor, Michigan
Ann Arbor, Michigan
Wilmington, North
Carolina
Poughkeepsie, New
York
Texas City, Texas
Population
Served
<10,000
132,000
115,000
115,000
75,000
75,000
92,000
Average
Annual
Treatment
Plant (MGD)
Production
2
27
20
20
25
16
12
Source
Water
Surface Water
(reservoir)
Ground Water
(surficial
aquifer)
Surface Water
(river, wells)
Surface Water
(river, wells)
Surface Water
(river)
Surface Water
(river)
Surface Water
(river)
Page
B-39
B-43
B-51
B-57
B-65
B-71
B-75
Section
Where It is
Referenced
in the
Manual
4.1
4.3
5.1
5.2
5.2
5.3
5.4
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
2-14
March 2007
-------
2. Quick Reference Materials for Simultaneous Compliance
Case
Study
No.
14
Treatment/Issue
Addressed
Chlorine Dioxide for
Primary Disinfection
and Chloramines for
Secondary
Disinfection
Utility Name
Village of Waterloo
Water Treatment
Plant
Case Study
Location
Waterloo, New York
Population
Served
<10,000
Average
Annual
Treatment
Plant (MGD)
Production
2
Source
Water
Surface Water
(lake)
Page
B-81
Section
Where It is
Referenced
in the
Manual
5.5
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
2-15
March 2007
-------
2. Quick Reference Materials for Simultaneous Compliance
Exhibit 2.6 Tools for Gathering System-Specific Information on Different Compliance Techniques
Compliance Techniques
Source Management
Distribution System BMPs
Moving the Point of Chlorination Downstream
Decreasing pH
Decreasing Chlorine Dose Under Warm Water
Conditions
Presedimentation
Enhanced Coagulation
Softening/Enhanced Softening
GAC
Microfiltration/Ultrafiltration
Nanofiltration
Other Microbial Removal Technologies including Bank
Filtration
Chloramines
Ozone
UV Disinfection
Chlorine Dioxide
S/j
a
'C
o
o
£
o>
"S
^
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
a
^ VI
£o
C -
CJ
'.5 &/J
3 fi
si
"^0
ffi s
X
X
X
X
X
X
X
X
X
« a
« -a G
"5 ^ G .3 -5 -3
o 'G S? eu & -2 ^ <3 h G
'^ !2 £ M Q « ^- 3 -^ £
J So Q-o H ^ ^ -o £ |
rvl W grt W C W ^* W i* TO p*
^* (J UO (JO tJCu
-------
Improving and Optimizing
Current Operations
Public water systems (PWSs) will
generally find that improving and optimizing
current operations is the best first step as they
consider changes to ensure continued compliance
with LT2ESWTR and Stage 2 DBPR. There are
several reasons for this.
• Operational changes to optimize
existing processes can often achieve
significant reductions in DBFs and
pathogens, improve disinfection, and
improve water quality without major
capital improvements. These changes
may be enough to achieve compliance;
• Operators are familiar with existing
processes, which will simplify the
transition;
OPERATIONAL PRACTICES
COVERED IN THIS CHAPTER
• Source Management
• Distribution System Best
Management Practices
• Moving Point of Chlorination
• Modifying pH During Chlorination
• Modifying Chlorine Dose Under
Different Temperature Conditions
• Modifying Pre-sedimentation
Basin Operations
• Enhanced Coagulation
• Enhanced Softening
• Even if improving and optimizing current operations does not get a system in
compliance by itself, it may allow for the use of a less expensive or simpler
technology to ensure compliance; and
• If existing technologies are not optimized, adding a new technology may not have the
desired effect or may cost more to operate.
This chapter addresses ways that water systems might change how they operate their
existing facilities to achieve compliance with the Stage 2 DBPR and LT2ESWTR. These
changes can be made individually or in combination to improve and optimize current operations
as a whole. Improving filter turbidity performance is in Chapter 4 instead of this chapter because
of the similarity of issues between this option and other filtration options included in Chapter 4.
Several options described in this chapter are ways in which water systems might modify
their existing Chlorination practices. Before making any significant changes to disinfection
practices, systems that are required (by the IESWTR, LT1ESWTR, and LT2ESWTR) to develop
a disinfection profile must calculate a disinfection benchmark for the treatment configuration
currently in place. To learn more about disinfection profiling and benchmarking, refer to EPA's
Disinfection Profiling and Benchmarking Guidance Manual (1999a).
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
3-1
March 2007
-------
Improving and Optimizing Current Operations
3.1 Source Management
For the purpose of this guidance, the term
source management refers to techniques that water
systems can use to manipulate their water source or
sources to comply with Stage 2 DBPR or
LT2ESWTR regulations. In this context, source
management does not refer to source water protection
or other long-term watershed efforts to improve water
quality. The source management techniques
discussed in this section are operational changes made
by water systems to use the source with the least
amount of contaminants, such as pathogens and
natural organic matter (NOM), or selecting a blend of
sources to try to achieve the most effective treatment for organics and turbidity removal.
Examples of source management include:
• Selecting the optimum depth from which to draw water. Systems using lake or
reservoir sources should have multi-level intakes. This flexibility allows the system
to draw water from different depths or
Water system managers should
check with their primacy agency
before making any source
management changes. Approval
of the primacy agency may be
required before a water system
modifies or switches its raw water
source.
locations, depending on the source
water quality during that time of year
or for other reasons (e.g. algal bloom,
storm upsets, etc);
• Blending various sources. Systems
that have multiple sources may
consider blending surface and ground
water sources to attain the best blended
raw water for compliance. If blended
prior to treatment, all water must be treated to surface water standards;
• Alternating between sources. Systems with multiple sources may consider alternating
between surface water and ground water sources depending on source water quality at
a given time. Systems may also temporarily discontinue use of a source for a period
of time when negative impacts are expected or water quality is poor; and
• Using the optimum intake. Systems may have more than one intake they can use to
draw from a source. By determining the intake with the highest water quality for
each particular time period, the system can obtain the optimum water quality year
round.
Many systems have one or more source management options available to them, while
others have limited opportunities to manage their source water quality in this way. Those
systems that think they could benefit from greater source management flexibility are encouraged
to diversify their options as feasible when they are planning capital improvements.
Simultaneous Compliance Guidance Manual 3-2 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Improving and Optimizing Current Operations
Source management may be considered as a temporary, seasonal, or permanent solution
depending on physical or chemical characteristics of the source; the need to reduce disinfection
byproduct (DBF) precursors, Cryptosporidium and/or turbidity; the availability of alternate,
additional, or new sources; and the impact the water chemistry change has on the rest of the
system. For example, a system may only have seasonal issues with DBF precursor
concentrations and, therefore, may decide to apply one or more source management techniques
on a seasonal basis.
Many factors can have a temporary or seasonal impact on surface water quality and can
impact organic loading, turbidity, and pathogen concentrations entering the plant. If these
impacts are understood and flexibility is built into the plant intake and operations, the system
may be able to use source management strategies to comply with the Stage 2 DBPR and
LT2ESWTR and avoid or mitigate simultaneous compliance issues. These factors include:
• Seasonal turnover - In colder climates many reservoirs and lakes experience turnover
during the spring and fall. When this occurs, sediment, organic matter and
particulates at the bottom of the reservoir can be stirred up and re-suspended. This
can lead to an increase in organic load, algal blooms causing taste and odor, turbidity,
and higher pathogen concentrations entering the plant;
• Precipitation events - Heavy rainfall or snowmelt can wash organic matter and
parti culates from soils into surface water sources. A runoff event upstream of the
intake can result in an increase in organic load and pathogens entering the plant;
• Algae blooms - Seasonal algae blooms that occur in lakes and reservoirs can impact
NOM levels and raw water pH in water nearer to the surface. Decayed algae can
contribute organics to sediment that later become problematic during turnover. Algae
blooms can also interfere with filter operation and may interfere with analysis for
Cryptosporidium and Giardia;
• Point source discharges - Discharges from wastewater treatment plants, water
treatment plants, and industrial discharges upstream of the intake can increase the
organic load and pathogens in source water. This becomes more significant when
stream flow decreases and there is less dilution; and
• Nonpoint sources of pollution - Nonpoint discharges of pollution can impact the
organic load in the source water. They can also increase microbial contaminants such
as Cryptosporidium and increase nutrients that can cause algal blooms. Many such
sources of pollution are intermittent or seasonal and, if the system is aware in
advance, adverse impacts can be avoided by temporarily discontinuing use of the
source.
If a ground water is used to supplement a surface water source on a seasonal basis, the quality of
the ground water should be considered, including its pH, iron and manganese concentrations,
oxidation reduction (redox) potential of the water, and any nearby contaminant plumes.
Simultaneous Compliance Guidance Manual 3-3 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Improving and Optimizing Current Operations
3.1.1 Advantages of Source Management
By using source management techniques, a PWS may be able to:
• Reduce DBF precursors in the raw water (reduction in raw water organic load);
• Reduce turbidity or pathogen levels in the raw water;
• Reduce oxidant or chlorine demand in the raw water and amount of disinfectant
used; and
• Improve treatability of raw water for turbidity and/or DBF precursors.
While changes to the source may be advantageous for minimizing DBF precursor
concentrations or turbidity, any major changes in the source water entering plants are likely to be
accompanied by corresponding changes in other raw water chemistry. These may include
changes in pH, temperature, alkalinity, organics, inorganics, radionuclides, etc. As a result, these
changes will have an impact on the treatment processes employed by the system and may impact
the distribution system as well. Therefore, when a source water change is considered, water
quality monitoring and jar testing should be conducted to determine the impacts the change in
water chemistry will have on the plant, as well as the
stability of the distribution system. Some, but not all
of these are included in Section 3.1.2.
Reduce DBFs
Jar testing should be conducted
when a system is considering a
source water change.
Selecting a source water or combination of source waters containing the least amount of
or more treatable organic matter can reduce finished water DBF concentrations. The water
chemistry of stratified lakes and reservoirs can change seasonally and vary significantly
depending on water depth. Different depths in a stratified source may contain different
concentrations of organics with different characteristics (e.g., particulate vs. dissolved, high vs.
low molecular weight). Water systems can use this to their advantage by determining the depth
containing the lowest DBF precursor concentrations or precursors that are most easily removed,
and then draw their source water from this depth. Systems should keep in mind, however, that
the depth producing the lowest concentration of DBF precursors may change seasonally. It is
important for an effective source management program to include routine monitoring to detect
changes in water quality at different intake depths and guide decision-making. Section 3.1.3
provides some suggestions for additional monitoring that can help in this way.
Blending sources can also produce lower finished water DBF concentrations if the
additional source used in blending contains lower concentrations of DBF precursors.
Reduce turbidity or pathogen level
Turbidity and pathogen concentrations can
vary depending on the location, timing, and
characteristics of the particles or pathogens. For
example, stratified reservoirs can have different
Routine reservoir monitoring can
help a system select the best
intake depth for minimizing
DBPs.
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
3-4
March 2007
-------
Improving and Optimizing Current Operations
turbidity levels at different elevations, especially during algae blooms. Certain pathogens can
also concentrate in one location of a reservoir. By being aware of the concentrations of particles
and pathogens at various locations in the water source the system can plan its withdrawals to
minimize the concentrations of these contaminants.
Reduce Amount of Disinfectant Used
Organic matter, inorganic matter, and biota such as algae in water usually present a
chlorine demand. If an alternative water source is used that is well-oxygenated and has lower
concentrations of organic matter, iron, and manganese, the water is likely to have a lower
chlorine demand than the poorer quality water previously used.
Raw Water Treatability
By drawing water from different depths in a stratified source, blending sources or
alternating sources, the raw water chemistry may also be manipulated to provide optimum
conditions for water treatability resulting in increased particulate removal. For example, systems
that have minimal alkalinity in the source water may find that blending another source water
with higher alkalinity may improve coagulation (when using alkalinity-dependent coagulants),
resulting in a reduction in DBF precursors and turbidity. In this situation, however, systems
should keep in mind that increasing alkalinity would in turn increase the amount of chemical
needed to lower the pH and effectively remove total organic carbon (TOC).
Different types of organic matter in water can be removed more or less effectively during
coagulation. In general, water containing primarily non-humic organic matter is less amenable
to enhanced coagulation. This type of water is also more likely to have a lower specific
ultraviolet absorbance (SUVA) concentration. By monitoring for NOM indicators such as
SUVA in their source water alternatives, water systems can pick the water that can be treated
more effectively for NOM removal and, possibly, reduce DBF concentrations in the finished
water.
By avoiding water with algal blooms, systems can improve the coagulation properties of
the water. Avoiding algal blooms can also reduce taste and odor compounds that are difficult to
remove during conventional treatment.
3.1.2 Potential Operational and Simultaneous Compliance Issues Associated
with Source Management Changes
Any changes to the raw water as a result of source management are likely to affect the
raw water chemistry and in some way impact treatment processes. While the goal may be to
minimize organic and/or pathogen loading or provide optimum conditions for DBF precursor and
turbidity removal, adverse changes in the raw water chemistry may include:
• Water temperature changes affecting CT (concentration x contact time)
calculations and coagulation and flocculation;
Simultaneous Compliance Guidance Manual 3-5 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Improving and Optimizing Current Operations
• Introduction of new contaminants or higher concentrations of existing
contaminants (e.g., iron, manganese, sulfide);
• Variation in raw water pH adversely affecting water treatment;
• Reduction in coagulation effectiveness or increased coagulant demand because
of other chemistry changes (e.g., alkalinity, type of turbidity);
• Changes in source water quality impacting corrosion control effectiveness;
• Increased disinfectant demand for water under reduced conditions (e.g., little or
no dissolved oxygen); and
• Changes in aesthetic quality may generate customer complaints.
Again, as noted in section 3.1.1, water quality monitoring should be conducted to determine the
impacts of changes in water chemistry. Section 3.1.3 lists additional parameters that systems can
monitor to guide their source management decisions. General suggestions for addressing some
of these issues that may arise as a result of source changes are provided below.
Changes in Water Temperature
If a water system's managers opt to draw from a lower level in a thermally stratified
reservoir during warmer months in order to decrease DBF precursors at the plant, the water
temperature may be considerably lower than the system typically experiences. It is not unusual
in northern parts of the U.S. for water temperatures near the top of a reservoir to be at least 10
degrees C higher than temperatures near the bottom. As water temperature decreases, pathogen
inactivation using most disinfectants is less effective, and therefore the required CT must be
increased. Since the system's contact time (T) is generally set, the disinfectant concentration (C)
may need to be increased when operating at maximum capacity. Therefore, the benefit gained
by changing the source to one with lower DBF precursors may be offset by the required increase
in disinfectant concentration, and little gain in terms of reducing finished water DBFs may be
realized. Alternatively, the lower temperature may slow down DBF formation reactions and
residual decay reactions that may mitigate the effect of temperature to some degree.
The converse, however, may also apply. If a system draws from a higher level in the
reservoir and there is a corresponding higher temperature, this may result in more efficient
inactivation and therefore less required CT.
Colder water temperatures also result in slower floe formation in the coagulation process
and therefore, decreased efficiency of turbidity removal (Faust and Aly 1998).
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Recommendations for Addressing this Issue
Systems may need to increase their CT when using a colder water source. Frequently a
system's T is set, especially when a system is operating at maximum capacity in the summer
months. Therefore, the disinfectant residual concentration may need to be increased in the
treatment plant.
Changes in temperature may require changes in coagulant dose, mixing speeds, and other
factors related to coagulation. To determine the impact colder water temperature may have on
the coagulation process, systems should conduct jar tests with the modified source water to
determine optimum conditions for coagulation based on the new water temperature and
chemistry. As the source water temperature and/or water chemistry changes, additional jar tests
should be conducted to determine the optimum conditions based on the new temperature or water
chemistry change.
Introducing New Contaminants or Higher Concentrations of Existing Contaminants
Contaminants such as arsenic, dissolved iron, dissolved manganese, or hydrogen sulfide
may be introduced or their concentrations may be increased depending on source management
decisions. For example, in the summer months a system may alternate its surface water source
with a ground water source to produce water lower in DBFs. This may, however, introduce
contaminants into the source water for which there is not adequate treatment in place for
removal, or the contaminant may deplete chemicals used in the treatment process that are needed
for other purposes (e.g., dissolved iron may deplete chlorine meant to be used for disinfection).
For systems using thermally stratified sources, drawing from a lower depth to avoid high
turbidities may introduce water with higher concentrations of dissolved organics or soluble
metals.
Another potential problem with a system introducing new contaminants or contaminants
at higher concentrations is the potential for increasing contaminant concentrations in the residual
waste streams of certain treatment processes. For example, if higher arsenic concentrations are
introduced in a conventional surface water plant, the arsenic will be oxidized and removed, and
will be concentrated in the sludge and backwash water.
Recommendations for Addressing this Issue
To address the problem of introducing or increasing contaminant concentrations in the
source water, systems should analyze the water chemistry of the alternate source for typical
constituents and suspected contaminants. Systems can then compare the alternate source's water
chemistry with the original source and consider the possible impacts prior to making source
changes. Section 3.1.3 provides some suggestions for additional monitoring to assist with this
decision making process. Once the new source water chemistry has been characterized, systems
using coagulants should conduct jar tests to determine if contaminant concentrations negatively
impact the treatment process. Several tests may be necessary to determine a source management
option that works best for meeting all treatment goals.
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Problems with a Change in Raw Water pH
A water system may change its source to decrease DBF precursors at the plant, but the
change may also affect the pH of the raw water. Variations in raw water pH will affect CT,
coagulation effectiveness for certain coagulants, and possibly DBF formation, unless pH is
controlled ahead of and through the treatment plant.
For systems that use chlorine to disinfect, pathogen inactivation is very dependent on pH.
As pH increases, inactivation is less efficient, and therefore the required CT must be increased.
Since the system's contact time is frequently set, the disinfectant concentration (C) may need to
be increased when operating at maximum flow. As with the impact from temperature, the
benefit gained by changing the source to one with lower precursors may be offset by the required
increase in disinfectant concentration. Under these circumstances, little gain may be realized.
Variations in the raw water pH can affect the coagulation process. The pH may no longer
be in the optimum range for coagulation using pH-dependent coagulants such as alum. Less
effective coagulation is likely to result in less DBF precursor removal, leaving more DBF
precursors available for reaction with chlorine or other disinfectants downstream in the treatment
process. If the pH of the source water is low and alum is used for coagulation, aluminum ions
may pass through the filters if alum is overdosed. A more detailed discussion of aluminum
solubility can be found in section 3.4.2.
Recommendations for Addressing this Issue
If the source water pH changes, water systems should conduct jar tests to determine
optimum coagulation/flocculation conditions based on the new pH. Systems should ensure that
corrosion control is adjusted accordingly if the pH change persists in water entering the
distribution system.
Reduced Coagulant Effectiveness
If source management is used to reduce DBF precursors, the turbidity of the raw water
may increase as a result. An increase in turbidity may result in increased coagulant demand and,
possibly, increased alkalinity demand. Water with increased turbidity may be more difficult to
treat, especially for systems that are not optimized or are nearing the design capacity of the
coagulation process. Higher influent turbidity can also lead to higher settled water turbidity and
problems with filtration.
Recommendations for Addressing this Issue
Systems should characterize the source water chemistry of the proposed new source or
blend of sources to ensure there are no negative impacts related to the coagulation process. Jar
tests should be performed if parameters that impact coagulation such as turbidity, alkalinity, pH,
or temperature change significantly.
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Changes in Corrosion Control Effectiveness
Systems using source management options such as blending various sources or
alternating between sources may experience changes in source water quality. This is especially
true for systems that switch from ground water to surface water, or vice versa. Fluctuations or
permanent changes to source water quality may impact the effectiveness of existing corrosion
control practices.
Recommendations for Addressing this Issue
Systems should characterize the source water chemistry of the proposed new source or
blend of sources to evaluate the impact of dissimilar waters on corrosion control. Systems may
need to make changes to their corrosion control process if there are differences in water quality.
Increased Disinfectant Demand for Waters under Reduced Conditions
When drawing from lower reservoir depths or from ground water sources, the water may
be under reduced conditions (with low or no dissolved oxygen (DO)). Dissolved iron,
manganese, and hydrogen sulfide may be present in these waters. The dissolved oxygen level at
which these agents become a problem is site specific and depends on other water quality
parameters such as pH and iron speciation. These reducing agents are readily oxidized by
disinfectants and, therefore, increase the disinfectant demand. In addition, dissolved iron and
manganese precipitate when oxidized, creating more turbid water and increasing the particle load
onto the filters.
Recommendations for Addressing this Issue
Water systems should be aware of the DO concentration and oxidation reduction
potential of the source water they are using. Chlorine dose should be adjusted to accommodate
the increased chlorine demand due to reduced conditions. Alternatively, systems may consider
periodic use of an additional oxidant, such as potassium permanganate, as a pretreatment to
oxidize reduced iron, manganese, or sulfide (Cooke and Kennedy, 2001). Aerating the water
before it is treated can be another effective way to eliminate reduced conditions.
Once they are oxidized, the inorganic chemicals that were formerly dissolved are likely to
precipitate. Water systems should carefully review their filter effluent turbidities to ensure that
additional particle loading is not stressing the filters. Systems should also conduct jar tests to
determine how to adjust their coagulant dose to improve removal of the additional particle load.
Changes in Aesthetic Quality May Generate Customer Complaints
When drawing from lower reservoir depths or changing to a groundwater source, systems
may draw in hydrogen sulfide, iron, manganese and other compounds that may cause taste and
odor problems. An increase in hardness may also generate customer complaints.
Recommendations for Addressing this Issue
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Systems that draw from anoxic layers in stratified reservoirs or from anoxic groundwater
may want to add a pre-oxidant to oxidize compounds such as iron, manganese, and hydrogen
sulfide (Cooke and Kennedy, 2001). Changes in hardness should be considered and lowered if
they become problematic by blending sources or by softening processes. Some systems may
want to notify customers of a source water change to explain why they may be seeing a change
in water characteristics at the tap.
3.1.3 Recommendations for Gathering More Information
See Additional References
Readers can turn to Section 7.1.4 in Chapter 7 for technical references associated with
source management.
Consider Additional Monitoring
Source management changes are likely to affect raw water chemistry. Additional
monitoring can help systems understand how treatment processes and other components of a
PWS will be affected by changes in the raw water chemistry. Water quality monitoring can also
be used for making source management decisions. For example, a system that monitors water
quality at its various intake depths can use measurements such as turbidity or TOC to decide
which intake gates to open and use. Many of these parameters can be monitored in real time to
provide immediate feedback into plant operation.
Systems choosing to use any of the source management options discussed in this section
should consider monitoring the applicable following parameters at a location before water enters
the treatment plant:
•S Dissolved Oxygen
- Ground water and stratified surface water sources
- DO profiles of lakes or reservoirs at the intake location using a field meter
•S Temperature
- All sources
- Temperature profiles of lakes or reservoirs at the intake location using a field
meter
S pH
- All sources
- pH profiles of lakes or reservoirs at the intake location using a field meter
•S Secchi disk depth
- Lakes and reservoirs to determine water clarity
•S Oxidation-reduction (redox) potential
- Ground water and stratified surface water sources using a field meter, if possible
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S Turbidity
S Alkalinity
•S NOM measured as TOC or SUVA
•S Dissolved iron
S Dissolved manganese
•S Hydrogen sulfide
S Other chemicals known to be problematic for ground or surface water sources in the
area
S Chlorophyll a and algal counts
Consider Other Tools
In addition to water quality monitoring, there are multiple tools available in Chapter 6 to
help systems evaluate and improve their current water system in relation to the compliance issues
they may face when modifying their operation or treatment practices. For example, the
AwwaRF report "Design of Early Warning and Predictive Source-Water Monitoring Systems"
(Grayman et al. 2001) provides guidance on the development of source water quality monitoring
systems that allow utilities to predict water quality events in the source water.
Readers are encouraged to read through Chapter 6 before making any final compliance decisions.
3.2 Distribution System Best Management Practices
The overall objectives of distribution system best management practices (BMPs) are to
maintain the quality of the treated water while also meeting water quantity, pressure, and service
reliability goals. If there is a significant increase of DBF concentrations from the finished water
to the distribution system, systems should consider implementing BMPs to lower DBF levels in
the distribution system. BMPs that can be particularly effective in reducing DBF formation in
the distribution system include:
• Water age management strategy
• Booster disinfection
• Water main flushing program
Other BMPs that are important for overall management of distribution system water quality
include but are not limited to a pressure management strategy, backflow prevention program,
procedures to prevent contamination during installation and repair of water mains, a pipeline
rehabilitation and replacement program, and finished water storage facility inspection and
cleaning program. These BMPs are also discussed briefly below.
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Water systems should prioritize the implementation of BMPs based on their system
conditions and needs. BMPs are particularly important for systems purchasing water from other
systems because the purchasers normally have limited flexibility for improving the water quality
entering the distribution system. Some systems may face operational and simultaneous
compliance issues when implementing distribution system BMPs, as discussed later in this
section.
Water Age Management Strategy
As water travels through the distribution system, chlorine continues to react with NOM to
form DBFs. Thus, increased water age can lead to higher DBF concentrations1. Other water
quality problems associated with increased water age include reduced disinfectant residual,
increased microbial activity, nitrification, and/or taste and odor problems.
Water systems should develop an overall strategy to manage the water age in their
distribution systems. Establishing a water age goal is system-specific depending on system
design and operation, water demands, and water quality (e.g. DBF formation potential). In the
US, the average distribution system retention time is 1.3 days and the average maximum
retention time is 3.0 days based on a survey of 800 medium and large water utilities (AWWA
and AwwaRF 1992).
Water age can be controlled through a variety of techniques including management of
finished water storage facilities, looping of dead-ends, and re-routing of water by changing valve
settings. Additional guidance is provided in the AwwaRF report, Managing Distribution System
Retention Time to Improve Water Quality (Brandt et al. 2004).
• Improve Mixing in Storage Facilities. Improving mixing in finished water storage
facilities can help eliminate stagnant zones. Old water in stagnant zones can often
have very high DBFs and no or low disinfectant residual. This water can be released
into the system during periods of high demand. Mixing can be improved by
increasing inlet momentum, changing the inlet configuration, increasing the fill time,
and by installing mixing devices within the storage facility. Hydraulic experts should
be consulted to determine which of these strategies will work for a given tank design
and configuration. Additional information is provided in an AWWA publication,
Physical Modeling of Mixing in Water Storage Tanks (Roberts et al. 2006).
• Minimize the Hydraulic Residence
Time in Storage Facilities. Increasing
volume turnover reduces the average
hydraulic residence time (HRT) in
finished water storage facilities, thereby
reducing DBF formation, loss of
disinfectant and microbial growth.
Kirmeyer et al. (2000b) recommend a
1 The extent of DBF formation in the distribution system is dependent on many factors and is site-specific. TTHM
levels typically increase with water age. Because HAAS can biodegrade, however, HAAS concentration may
decrease with advanced water age in areas of the distribution system with low or non-detectable disinfection
residuals and increased microbial activity. See Section 7.1.2 for references on DBF formation.
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complete turnover every three to five days but suggest that water system's establish
their own turnover goal based on system-specific needs and goals. Turnover can be
accomplished by increasing the water level fluctuation or drawdown between fill and
draw cycles. The water level should be lowered in one continuous operation not
small incremental drops throughout the day. Converting tanks to eliminate common
inlet/outlet configurations can also reduce average HRT.
• Decommission Storage. Decommissioning storage facilities may be an appropriate
strategy to reduce water age if existing facilities are oversized and not needed for
emergency conditions, fire protection, or for maintaining system pressure. A
professional engineer should review system needs, system design, and operation to
determine if the existing storage capacity is appropriate.
• Minimize Hydraulic Residence Time in Pipes. Minimizing the HRT in pipes can
help reduce the time available for DBF formation, although it is possible for an
increase in HAAS to occur because of less biological degradation. Reducing HRT
can also minimize disinfectant residual loss and allow systems to use a lower overall
residual concentration, thereby reducing DBFs. Systems can reduce HRT and
disinfectant loss through physical system improvements such as looping dead ends,
installing blow-offs, and replacing oversized pipes. These can be expensive,
however, and cost-prohibitive for some systems.
Booster Disinfection
Booster disinfection can improve disinfectant residual maintenance and minimize
formation of DBFs by allowing systems to reduce the chlorine residual leaving the treatment
plant and feed chlorine at select locations in the distribution system to maintain a residual.
Systems can reduce the booster disinfectant dosage rate by first reducing the disinfectant demand
within the piping system through various maintenance programs. For example, periodic flushing
of the water mains removes loose sediment. Cast iron pipes can be cleaned and lined with
materials that are less prone to microbial growth or have less potential for consuming oxidants.
Develop and Implement a Water Main Flushing Program
A water main flushing program helps to keep the system clean and free of sediment,
reduces the disinfectant demand of pipe surfaces, and removes stagnant water and any untreated
or contaminated water that enters the system (Kirmeyer et al. 2000b). Flushing can also be used
to address water quality deterioration at dead-ends. If a dead-end is unavoidable, industry and
regulatory guidance recommend fitting dead-ends with hydrants or blow-offs for flushing
purposes (Friedman et al. 2005).
Minimum elements of a flushing program are outlined in the AWWA G200 Standard
(AWWA 2004e) and include: (1) a preventive approach including spot flushing to address local
problems or customer concerns and routine flushing to avoid water quality problems; (2) use of
an appropriate flushing velocity to address water quality concerns; and (3) written procedures for
all elements of the flushing program including water quality monitoring, regulatory requirements
and specific flushing procedures.
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Kirmeyer et al. (2000b) developed an approach to assist utilities with developing,
implementing, and evaluating the effectiveness of flushing programs. The program includes four
steps:
• Step 1: Determining the Appropriateness of Flushing as Part of a Utility
Maintenance Program. In this step, the water system conducts a self-assessment to
determine if flushing is needed to maintain distribution system water quality and what
type of flushing is warranted. For example, yes answers to the following questions
would indicate a need for flushing:
- Do you experience frequent water quality-related customer complaints?
- Do you have difficulty maintaining a disinfectant residual in portions of the
distribution system?
- Does sediment accumulate in finished water storage facilities?
If the water system determines that flushing is needed, a second self-assessment can
help determine the feasibility of conducting an effective flushing program. Questions
to consider prior to initiating flushing may include:
- Will hydraulic constraints prevent the achievement of desired flushing velocities?
- Is enough water available to flush at desired velocities for desired duration?
- What are the requirements for disposing of the water?
• Step 2—Planning and Managing a Flushing Program. In this step, the water
system identifies flushing objectives, determines the most effective flushing
approach, and establishes specific flushing procedures. Flushing objectives may
involve both water quality considerations as well as hydraulic and maintenance
considerations. One or more flushing approaches may be appropriate, unidirectional,
conventional, and/or continuous blow-off depending on system configuration and
flushing objectives. Each approach can be implemented on a comprehensive, system-
wide basis or on a more limited "spot" basis. Other important planning activities
include notifying customers of flushing activities and identifying sensitive users that
may be impacted by temporary water quality changes as a result of flushing;
• Step 3—Implementing a Flushing Program and Data Collection. Water quality
monitoring and documentation of costs provide information needed to evaluate the
program (Step 4); and
• Step 4—Evaluating and Revising a Flushing Program. Kirmeyer et al. (2000b)
suggest that experimenting with flushing velocities, duration, and frequency may help
the water system establish a flushing program that meets water quality goals within
their operating budget. Additional guidance is provided in an AwwaRF report, Cost
and Benefit Analysis of Flushing
(DeNadai et al. 2004).
Care should be taken regarding disposal of
disinfected water. The AwwaRF report Guidelines
for the Disposal of Chlorinated Water (Tikkanen et
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al. 2001) provides strategies for removing chlorine and choramine from water during flushing.
See Section 3.2.3 for additional information.
In some cases, flushing may not be adequate to clean water mains. Techniques such as
pigging may be needed to remove accumulated material.
Other BMPs for Maintaining Distribution System Water Quality
• Pressure Management Strategy. Pressure losses can occur in the distribution
system as a result of events such as flushing, main breaks, power outages, service line
breaks, and fires. Pressure transients (also called pressure surges or water hammer)
can occur when an abrupt change in water velocity occurs, due to a sudden valve
closure, pump shutdown or loss of power. The resulting pressure wave, with
alternating low and high pressures, travels back and forth through the distribution
system until the pressure is stabilized. Low pressure conditions in the distribution
system can allow a flow reversal or backflow of non-potable water to enter the system
from a cross connection or other source. Pressure transients can also create hydraulic
disturbances that allow biofilm material on pipe surfaces to enter the bulk water.
Industry guidelines suggest that system pressure should be maintained within the
range of 35 to 100 psi at all points in the distribution system (AWWA 1996). The
AWWA G200 standard indicates that the minimum residual pressure at the service
connection under all operating conditions should be > 20 psi (AWWA 2004c).
Written standard operating procedures for pump, hydrant and valve operation under
routine and emergency conditions can help minimize sudden changes in water
velocity that impact system pressure;
• Backflow Prevention Program. The National Research Council (2006) ranked cross
connections and backflow events as the highest priority concern for water
distribution systems. Systems should have cross connection control and backflow
prevention programs that meet state regulatory requirements and adhere to industry
guidelines (AWWA 2004c);
• Program to Prevent Contamination During Installation and Repair of Water
Mains. Contamination of the distribution system following water main breaks or new
installations was identified as a high priority issue by the National Research Council
(2006). The AWWA Standard C651-05 (AWWA 2005c) provides a method for
disinfecting newly constructed water mains or water mains that have undergone
repairs. Pierson et al. (2001) developed comprehensive best practices to prevent
microbiological contamination of water mains covering topics such as site conditions;
condition and storage of materials; general construction/repair practices; preparing for
service; and project closeout;
• Pipeline Rehabilitation and Replacement Program. A comprehensive program to
assess and upgrade water mains will help maintain water quality and to provide
reliable service. Pipe replacement and various types of pipe lining can help improve
water quality as well as increase carrying capacity of pipes. AWWA Standard G200
(AWWA 2004c) and several AwwaRF publications provide guidelines for program
elements; and
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Finished Water Storage Facility Inspection and Cleaning Program. Regular
inspection of storage facilities provides information needed to plan facility
maintenance and to minimize contaminant entry to the system. Kirmeyer et al.
(2000b) identifies three types of inspections - routine, periodic and comprehensive.
Routine inspections, conducted on a daily to weekly basis, are primarily a visual
inspection of the tank's structural integrity and the site's security. Periodic
inspections, conducted every one to four months, require climbing the tank to visually
inspect areas not normally accessible from the ground. Comprehensive inspections
are conducted every three to five years depending on state requirements and industry
guidelines. Comprehensive inspections evaluate the structural condition of storage
facility components including interior features. Kirmeyer et al. (2000b) recommends
that covered facilities be cleaned every three to five years, and uncovered storage
facilities be cleaned once or twice per year. The cleaning frequency should be set
based on system-specific information such as inspection reports and water quality
monitoring data.
3.2.1 Advantages of Distribution System BMPs
Depending on treatment and distribution system configuration and characteristics of DBF
formation, distribution system BMPs may be less expensive ways to achieve compliance with the
Stage 2 DBPR compared to advanced treatment options. Other advantages to implementing
distribution system BMPs include:
• Target specific problem areas
• Improve microbial control
• Improve chlorine residual maintenance
• Reduce corrosion
• Reduce nitrification
Target Specific Problem Areas
Many of the BMPs such as flushing, booster disinfection, and management of finished
water storage facilities can target specific problem areas rather than apply a solution to the entire
system. This is an efficient way to improved water quality in the distribution system.
Improve Microbial Control
In additional to reducing DBF formation, most BMPs will improve microbial control by
helping to maintain a disinfectant residual and/or reducing biofilms and sediments that encourage
biological growth. Improved microbial control can result in fewer Total Coliform Rule
violations, fewer violations of the Surface Water Treatment Rule requirement to maintain a
disinfectant residual, and less potential for microbiologically-induced corrosion.
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Improve Chlorine Residual Maintenance
The National Research Council (2006) ranked loss of disinfectant residual as a medium
priority concern for water distribution systems because ".. .it is an indirect health impact that
compromises the biological integrity of the system and promotes microbial regrowth." Long
hydraulic residence times, microbial growth, and corrosion products will all deplete the
disinfectant residual. The BMPs seek to reduce these factors and will therefore result in higher
and more consistent residuals throughout the distribution system.
Reduce Corrosion
Corrosion can cause Lead and Copper Rule compliance problems, aesthetic problems, and
may eventually lead to leaks that can be sources of contamination to the system. Corrosion of
cast iron pipes can provide a habitat for microorganisms and increase the likelihood of TCR
violations. Some BMPs, such as pipe replacement or lining, can reduce corrosion.
Reduce Nitrification
The occurrence of nitrification in chloraminated systems can be reduced through the use of
distribution system BMPs. Reducing water age and controlling microbial growth will help
reduce nitrification episodes by slowing the decay of chloramines and providing less free
ammonia for nitrification.
3.2.2 Potential Operational and Simultaneous Compliance Issues Associated
with Distribution System BMPs
Challenges of implementing the BMPs depend largely on the specific BMP. Examples of
these challenges include:
• Re-suspension of sediments
• Issues with disposal of disinfected water
• Lining materials leaching into the water
• Less storage available for emergencies
• Increased water loss
Re-suspension of Sediments
Some BMPs such as increasing storage pumping rates, using blow-offs, or flushing of
pipes can cause re-suspension of sediments that had settled in the storage facilities or pipes.
These sediments can cause temporary aesthetic complaints and may also contain microbes or
particulate metals such as lead, copper, and iron.
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Recommendations for Addressing this Issue
A properly implemented flushing program can remove the sediments from the pipes and
can result in a positive long-term impact. There are many references listed in the Section 7.1.5,
Distribution System Management, that can that can be used to plan, design, implement, and
monitor an effective flushing program (AWWA 2002; AWWA 2005b; Kirmeyer et al. 2000b).
Issues with Disposal of Disinfected Water
When flushing water distribution mains or draining storage facilities prior to cleaning or
inspections, utilities should be aware of state or local regulations on disposal of chlorinated or
chloraminated water. If flushed water flows directly into natural waters, systems may need to
remove the disinfectant chemicals prior to discharge to protect the aquatic environment. The
National Pollution Discharge Elimination System is a Federal program established under the
Clean Water Act, aimed at protecting the nation's waterways from point sources of pollution.
Effluent limitations vary depending on receiving water characteristics (use classification, water
quality standards, flow characteristics) and discharge characteristics (flow, duration, frequency).
Recommendations for Addressing this Issue
The AwwaRF report, Guidelines for the Disposal of Chlorinated Water (Tikkanen et al.
2001) provides information on dechlorination techniques in use by water systems. Some utilities
use straightforward field methods such as a bag filled with a de-chlorinating agent placed in the
flowing water, while other systems have sophisticated metering and storage equipment installed
in trailers.
Lining Materials Can Leach Into Water
Some lining materials can leach chemicals into the water if not properly handled or
applied.
Recommendations for Addressing this Issue
It is important to make sure the lining material has been independently certified against
NSF/ANSI Standard 61. Manufacturers' instructions and appropriate standards should be
followed in lining the pipe and returning it to service as well. In addition to following the
certifying agency's and manufacturer's recommendations, many utilities will conduct their own
water quality tests for compounds of interest including VOCs and taste and odor-causing
compounds before a new lining is returned or released to service.
Less Storage Available for Emergencies
Removing finished water storage facilities from service, while reducing DBFs and
improving microbial control, can result in less storage available for emergencies such as drought,
earthquakes, main breaks, firefighting, etc. To a lesser extent, some of the other finished water
storage BMPs can also reduce the amount of storage available for such events.
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Recommendations for Addressing this Issue
Before changes are made to finished water storage, an analysis should be made of system
demand and pressure needs and fire flow requirements. This analysis should review appropriate
fire ordinances to determine the amount needed. In addition, emergency storage requirements
should be addressed. Hydraulic models in combination with source planning can help determine
the amount of water to be maintained in storage in various parts of the system. Section 6.3
identifies several hydraulic models that may be helpful.
Increased Water Loss
Flushing programs will lead to a loss of water. This is an added expense and could be
troublesome in areas where sufficient water supply is a concern.
Recommendations for Addressing this Issue
The advantages of system flushing often outweigh the cost of lost water. Systems may,
however, want to minimize water loss through careful design of the flushing program. For
example, Friedman et al. (2003) found that systems that had previously conducted one round of
high velocity unidirectional flushing (> 5fps) within the last 4-6 years had likely removed all
loose, compacted and adhered deposits and may not benefit from additional high velocity
flushing. Use of automatic flushing devices may help control flushing volume and reduce water
loss. Examining customer complaint and water quality records can help to focus flushing to the
areas and times where they are most needed. A public outreach program can help minimize
customer perceptions that the utility is wasting water when they observe flushing activities in
progress. Additional guidance may be found in an AwwaRF report, Cost and Benefit Analysis of
Flushing (DeNadai et al. 2004).
3.2.3 Recommendations for Gathering More Information
Read the Case Study
For more information on simultaneous compliance issues associated with distribution
system BMPs, see Case Study #1 - Improving and Optimizing Current Operations starting on
page B-5 of Appendix B. This case study describes how two small PWSs with high THM
concentrations were able to comply with the requirements of the Stage 1 D/DBPR and Stage 2
DBPR by adjusting their coagulation methods and changing the point of chlorination, while also
optimizing distribution operations to minimize water age and optimizing booster chlorine use.
See Additional References
Readers can turn to Section 7.1.5 in Chapter 7 for technical references associated with
Distribution System BMPs.
Consider Additional Monitoring
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The following are some suggestions for additional monitoring that may benefit water
systems implementing distribution system BMPs:
S Take routine measurements of chlorine residual and heterotrophic plate count (HPC-
R2A) in water leaving storage tanks and other distribution system locations with long
residence times and in chloraminated systems. Online chlorine analyzers at storage
facilities may be helpful;
S Monitor water quality at dead-end mains. Monitoring parameters may include
disinfectant residual, turbidity, coliform bacteria, HPC counts, and DBFs;
S Increase measurements of total coliform, HPC, chlorine residual, and turbidity in
distribution system locations during flushing;
S Periodically monitor pipe metals (e.g., iron if cast iron pipes are used, lead if lead
solder is used) in distribution system regions where corrosion is suspected; and
-S Monitor pertinent chemicals and odor downstream of pipes that have been recently
lined or replaced.
The Stage 2 DBPR Initial Distribution System Evaluation Guidance Manual (USEPA
2006a) provides distribution system water quality monitoring requirements for the Stage 2 DBPR
and can be used to identify locations that tend to have high DBF levels.
The AwwaRF report, "Guidance Manual for Monitoring Distribution System Water
Quality" (Kirmeyer et al. 2002), can be used to assist water utilities in implementing a
distribution system water quality data collection and analysis program.
Consider Other Tools
In addition to water quality monitoring, there are additional tools available in Chapter 6
to help systems evaluate and improve their current water system in relation to the compliance
issues they may face when modifying their operation or treatment practices. Examples of tools
that can be used when distribution system best management practices are used for Stage 2 DBPR
compliance include:
• Computer hydraulic and water modeling software, such as EPANET (USEPA 2002b),
that can be used to simulate hydraulic detention time and water quality in the
distribution system; and
• The AWWA manual "Computer Modeling of Water Distribution Systems" (AWWA
2004a) that provides step-by-step instructions for the design and use of computer
modeling for water distribution systems.
Readers are encouraged to read through Chapter 6 before making any final compliance decisions.
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3.3 Moving the Point of Chlorination
At conventional surface water treatment plants, chlorine
can be added for prechlorination at either the raw water intake or
flash mixer, for intermediate chlorination ahead of the filters, for
postchlorination at the clearwell, or for rechlorination of the
distribution system. While inactivation of pathogenic organisms
is its primary function, chlorine is used in drinking water
treatment for several other purposes, including:
• Control of nuisance Asiatic clams and zebra mussels
• Oxidation of iron and manganese
• Improved coagulation
• Taste and odor control
• Prevention of algal growth in sedimentation basins and filters
• Color removal
Exhibit 3.1 summarizes the typical uses for each point of chlorine application.
Exhibit 3.1 Typical Chlorine Points of Application and Uses
Point of Application
Raw Water Intake
Flash Mixer or Rapid Mix (prior to sedimentation)
Filter Influent
Filter Clearwell
Distribution System
Typical Uses
Zebra mussel and Asiatic clam control, control
biological growth
Disinfection, iron and manganese oxidation,
improved coagulation1, taste and odor control,
oxidation of hydrogen sulfide, algae control
Disinfection, control biological growth in filter,
iron and manganese oxidation, taste and odor
control, color removal
Disinfection, disinfectant residual
Maintain disinfectant residual
Source: Alternative Disinfectants and Oxidants Guidance Manual, USEPA 1999b.
1Not included as a typical use in the above reference, but documented by research
Public water systems with conventional treatment might consider moving the application
point for chlorine downstream within the plant to a point after DBF precursors have been
removed. Depending on the treatment plant, THM formation potential can be decreased by up to
50 percent as a result of precursor removal during coagulation and sedimentation (Singer and
Chang 1989).
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3.3.1 Advantages of Moving the Point of Chlorination
By moving the point of chlorination downstream in the treatment process, a PWS can:
• Reduce DBF concentrations in the finished water
• Reduce amount of disinfectant used
• Facilitate monthly TOC source water monitoring
Reduces DBFs
Summers et al. (1996) presented the results from four studies evaluating the impact of
pretreatment on DBF formation. Jar tests were conducted to simulate water treatment through
rapid mix, coagulation, flocculation, and sedimentation. Chlorine was added at various points in
the jar testing to simulate the impact of various dose points on production of DBFs. The results
demonstrate the benefits of delaying the point of chlorination downstream in the treatment train
to take advantage of precursor removal during flocculation and sedimentation processes. Exhibit
3.2 summarizes the results from this study.
Exhibit 3.2 Percent Reduction in DBP Formation by Moving Point of Chlorination
Chlorination Point
Pre rapid mix
Post rapid mix
Mid flocculation
Post sedimentation
TTHM
Baseline (%)
Baseline
2
9
21
TTHM
Enhanced (%)
17
21
36
48
HAAS
Baseline (%)
Baseline
5
14
35
HAAS
Enhanced (%)
5
21
36
61
Notes: Source: USEPA 1997 based on Summers et al. 1996
Baseline = Baseline coagulant (alum) dose for optimal turbidity removal (-30 mg/L)
Enhanced = Enhanced coagulant (alum) dose for optimal TOC removal (~ 52 mg/L)
Exhibit 3.2 also includes a comparison of total trihalomethane (TTHM) and haloacetic
acid (five) (HAAS) concentrations when enhanced coagulation was used, and the benefits of
enhanced coagulation for reducing DBP production. The TTHM formation reduction of 21
percent by moving the chlorination point to post sedimentation is more than doubled to 48
percent by enhanced coagulation. The reduction in HAAS formation increases from 35 to 61
percent under enhanced coagulation with post sedimentation chlorination. Therefore, DBP
control by selecting the optimal dose location and conditions, along with enhanced precursor
removal, can significantly reduce DBP formation. For a more detailed discussion of enhanced
coagulation and its simultaneous compliance issues, refer to Section 3.7 of this manual.
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Reduces Amount of Disinfectant Used
If a system moves its point of chlorination downstream after a significant amount of
organic matter has been removed, the chlorine demand of the water will be lower. In some
cases, the system may be able to take advantage of the reduced chlorine demand to reduce the
overall chlorine dose needed to achieve the required CT. The system would benefit not only in
reduced chemical costs, but may also reduce operational costs if they decrease their number of
chlorine injection points.
Facilitates Source Water TOC Monitoring
The Stage 1 D/DBPR requires surface water systems (or systems using ground water
under the direct influence of surface water) using conventional filtration treatment to monitor
each treatment plant for TOC removal. Systems are required to collect TOC samples from the
source and the treated water. Source water TOC samples must be collected prior to any
treatment, including chlorination.
Some PWSs that are required to conduct TOC sampling prechlorinate at or near the
source water intake. These systems currently have to turn off their chlorination in order to
collect a proper source water TOC sample. Although it's a minor benefit of moving chlorination
downstream in the treatment process, those systems would no longer have to turn off their
chlorination in order to collect their source water TOC sample.
3.3.2 Potential Operational and Simultaneous Compliance Issues Associated
with Moving the Point of Chlorination
Many PWSs benefit from other functions of prechlorination in addition to its use as a
disinfectant. Chlorine can oxidize iron and manganese, improve coagulation, enhance color
removal, improve taste and odor, as well as control biological growth at different stages of
treatment. Because it has several other functions, some PWSs may find that there are drawbacks
to moving the point of chlorination further downstream in the treatment process. Moving the
point of chlorination further downstream in the treatment process can:
• Raise issues with meeting CT requirements
• Increase filter fouling
• Limit Asiatic clam or zebra mussel control
• Limit coagulation and filtration effectiveness
• Provide less effective treatment for iron and manganese
• Affect pH of water being treated, possibly requiring adjustment of water
treatment chemistry
This section discusses these issues and provides some recommendations for addressing them.
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CT'Issues
Disinfection effectiveness is measured in terms of CT. If a PWS receives CT credit for
contact time prior to filtration and then moves its point of chlorination further downstream in the
treatment process, the system will likely have to increase its C to accommodate reduced T.
Systems should carefully evaluate their disinfection profiles to ensure that they continue to meet
benchmarking requirements. Guidance is provided in the Disinfection Profiling and
Benchmarking Guidance Manual (USEPA 1999a).
If concentration of disinfectant is increased, high disinfectant residuals may persist into
the distribution system. A public water system, however, must maintain disinfectant residual
concentrations that meet the MRDL requirements of the Stage 1 D/DBPR. The running annual
average (RAA) of the free chlorine residual measured in the distribution system must not exceed
the 4.0 mg/L MRDL. Also, if the chlorine residual in the delivered water is increased, the
number of customers that will notice a chlorinous odor may increase and generate more frequent
customer complaints.
Recommendations for Addressing this Issue
Systems should examine hydraulic conditions and maximize contact time where possible.
Clearwells can be modified (e.g., baffling and/or improved inlet and outlet structures added) to
improve their hydraulic performance. Constructing additional storage or dedicated disinfection
contact basins can also increase CT.
A water system should evaluate the CT that it can achieve downstream of the new
application point to ensure that sufficient CT can be maintained once the point of chlorination
has been moved. The evaluation should be done for the organism for which the disinfectant is
least effective. A system may also want to break up its CT segments into smaller segments. For
example, if the section from the raw water intake until the filters had been considered as a single
section for performing CT calculations and the point of chlorination is moved until after the
flocculation basin, a system can still receive some credit for section between the flocculation
basin and the filters. See the Disinfection Profiling and Benchmarking Guidance Manual
(USEPA 1999a) for more details on calculating CT and using segments. This evaluation should
review seasonal impacts on CT (e.g., cold water conditions when higher CT values are needed or
if the water's pH increases during algae blooms in the warmer water months).
If having too high of a residual in the distribution system is an issue a system may be able
to extend its contact time instead. Reducing chlorine demand may also help to achieve the
required inactivation with a lower chlorine dose.
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Potential for Increased Filter Fouling
Prechlorination is often used to minimize operational problems associated with biological
growth in water treatment plants. Prechlorination can prevent slime formation on filters, pipes,
and tanks, and reduce potential taste and odor problems associated with such slimes. It can also
prevent algal growth which can clog filters and cause turbidity problems. Many sedimentation
and filtration facilities operate with a small chlorine residual to prevent growth of algae and
bacteria in the launders and on the filter surfaces.
Recommendations for Addressing this Issue
If a system is concerned about the potential for algal growth and filter fouling after
prechlorination is stopped, there are alternatives the system can consider. If chlorine is being
added before the coagulation and flocculation steps,
operators may want to consider moving the chlorination
point so that it follows these steps but comes before
filtration. Adding chlorine immediately before the
filters may be an effective way for the system to prevent
filter fouling, yet not allow the chlorine to come into
contact with the water when the water still contains
unsettled DBF precursors (see case study No. 1 in
Appendix B).
Adding chlorine immediately
before the filters may be an
effective way for the system to
prevent filter fouling from
biological growth.
Systems may be able to eliminate the prechlorination step at certain times of the year, and
return to prechlorination when microbial fouling is more likely to occur during the treatment
process, such as when there is algal growth in the source water. They may also consider
continuing to prechlorinate, but adjusting the prechlorination dose depending on source water
conditions or water temperature.
Lastly, a system may consider using an alternative preoxidant, such as potassium
permanganate or chlorine dioxide. These oxidants can provide benefits similar to chlorine in
terms of iron, manganese, or algae control without forming significant amounts of TTHM or
HAAS. They can also reduce chlorine demand before chlorination is applied. Readers should
refer to the Alternative Disinfectants and Oxidants Guidance Manual (USEPA 1999b) for more
information.
Asiatic Clam and Zebra Mussel Control
The Asiatic clam (Corbicula flumined) was introduced to the United States from
Southeast Asia in 1938 and now inhabits almost every river system south of 40° latitude
(Problem Organisms in Water Treatment: Britton and Morton 1982, Counts 1986). This mollusk
has invaded many source waters, clogging source water transmission systems and valves,
screens, and meters; damaging centrifugal pumps; and causing taste and odor problems.
The zebra mussel (Dreissenapolymorphd) population in the United States has expanded
very rapidly. Zebra mussels have been found in the Great Lakes, Ohio River, Cumberland River,
Arkansas River, Tennessee River, and the Mississippi River south to New Orleans (Lange et al.
1994).
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Many PWSs add chlorine at their intakes to control Asiatic clam and zebra mussel
growth. For those systems with intakes a significant distance from their treatment plants,
prechlorinating for zebra mussel control may allow a substantial amount of time for TTHM or
HAAS formation prior to any precursor removal process.
Recommendations for Addressing this Issue
Asiatic Clams
Systems that add chlorine to control Asiatic clams and have problems with elevated
TTHM or HAAS concentrations may want to consider using an alternative oxidant, such as
monochloramine or chlorine dioxide, to control clam growth in their systems. If
monochloramine is used, water systems using the monochloramine to also satisfy CT
requirements will need to perform a disinfection benchmark, bearing in mind that the CT
required for viral inactivation using chloramines is substantially greater than that for chlorine,
and should ensure that adequate disinfection is being provided after switching disinfectants.
Monochloramine was found to
work well for controlling juvenile
clams without forming DBFs.
Cameron et al. (1989) compared the
effectiveness of free chlorine, potassium
permanganate, monochloramine, and chlorine
dioxide for controlling the juvenile Asiatic clam.
Monochloramine was found to be the best for
controlling juvenile clams without forming DBFs. Further research showed that the
effectiveness of monochloramine increased greatly as the temperature increased (Cameron et al.
1989). Belanger et al. (1991) showed that pre-formed monochloramine with excess ammonia
was more effective for controlling Asiatic clams than either total residual chlorine,
monochloramine, bromine, or copper. Chlorination at 0.25 to 0.40 mg/L total chlorine residual
at 20 to 25° C controlled clams of all sizes, but the same dosage had minimal effect at 12 to 15°
C.
Zebra mussels
Systems with elevated DBFs may also want to consider using an alternative zebra mussel
control strategy. Permanganate has been found to be effective for zebra mussel control and has
been used. Chlorine dioxide and ozone have shown promise as effective oxidants that can be
used for zebra mussel control. Antifouling coatings can work by slowly releasing into the water
a toxic substance, often an organo-metallic compound that prevents the zebra mussel larvae from
settling on the pipes. PWSs should check with their State if they are considering a chemical
control method, to make sure that the chemical is approved for use in a drinking water supply.
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There are many other approaches to zebra mussel control being developed and tested.
These methods include:
• The use of electrical fields to kill veligers (zebra mussel larvae)
• Ultrasonic treatment to prevent settlement
• Oxygen deprivation
• Sand infiltration beds
• Thermal control (AWWA 2003 c)
In addition, some polymers have been tested recently that show promise.
Coagulation and Filtration Effectiveness
Research has shown that using a preoxidant ahead of coagulation can have a positive
effect on coagulation and filtration with respect to particle removal (Becker et al. 2004). By
moving chlorination to a point after filtration, a water system may find that it needs to develop
new strategies for turbidity and particle control.
Recommendations for Addressing this Issue
Water systems moving chlorination to a point after filtration that can no longer achieve
low filter effluent turbidity values or particle counts may want to consider using a preoxidant
other than chlorine to improve filter performance. The strongest preoxidants have shown the
maximum benefit to filtration, so a system can achieve similar benefits by applying chlorine
dioxide or ozone. Systems that choose to do this should consult the Section 5.4 (chlorine
dioxide) or Section 5.2 (ozone) of this guidance manual to determine possible effects of these
steps.
Iron and Manganese Control
Although not harmful to human health at the low concentrations typically found in water,
iron and manganese can cause staining and taste problems. Iron and manganese compounds are
treated by oxidation to produce a precipitate that is subsequently removed by sedimentation and
filtration. Systems with high manganese levels should also be aware that a manganese coating
may have developed on their filters when pre-oxidation was practiced. This layer could dissolve
if pre-oxidation is no longer practiced and/or the pH drops (Angara et al 2004).
Recommendations for Addressing this Issue
Systems should be careful to consider how eliminating prechlorination may impact other
removal mechanisms during the treatment process. Some may be able to use an alternative
oxidant or reduce their prechlorination dose if the chlorine dose required for iron or manganese
removal is lower than what is currently being added. The oxidation of iron and manganese can
usually be accomplished while maintaining a minimum residual. Potassium permanganate is an
effective alternative oxidant to chlorine for iron and manganese oxidation and does not result in
TTHM or HAAS formation. Various alternatives are discussed in greater detail in the
Alternative Disinfectants and Oxidants Guidance Manual (USEPA 1999b) and the Guidance
Manual for Enhanced Coagulation and Precipitative Softening (USEPA 1999h).
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Problems with a Change inpH
Impacts of pH changes on
compliance and operational
issues associated with pH are
described in Section 3.4.
Moving the point of chlorination or
eliminating prechlorination may result in a change in
water pH. Adding gaseous chlorine decreases
water's pH, whereas adding hypochlorite increases
water's pH.
Recommendations for Addressing this Issue
Water systems that use a coagulant should consider whether the elimination of
prechlorination and the resulting change in pH would require the system to adjust its coagulant
dose or add other chemicals to control pH. Systems with corrosion control should also consider
whether a pH change due to the elimination of prechlorination would require the system to alter
its corrosion control chemical dose. Impacts of pH changes on compliance and operational
issues are described in Section 3.4.
3.3.3 Recommendations for Gathering More Information
Read the Case Study
For more information on simultaneous compliance issues associated with moving the
point of chlorination and how to address them, see Case Study #1 - Improving and Optimizing
Current Operations starting on page B-5 of Appendix B. This case study describes how two
small PWSs with high THM concentrations were able to comply with the requirements of the
Stage 1 D/DBPR and Stage 2 DBPR by adjusting their coagulation methods and changing the
point of chlorination, while also optimizing distribution operations to minimize water age and
optimizing booster chlorine use.
See Additional References
Readers can turn to Sections 7.1.1, 7.1.2, 7.1.6, and 7.1.17 in Chapter 7 for technical
references associated with moving the point of chlorination.
Consider Additional Monitoring
The following are some suggestions for additional monitoring that may benefit water
systems moving their point of chlorination:
v' Water systems that reduce or eliminate prechlorination should carefully review pH
data to ensure that treatment processes and materials will not be adversely affected;
^ Systems with the potential for iron or manganese problems that move, reduce, or
eliminate prechlorination should consider monitoring for those metals at the entry
point to the distribution system. Those systems with clearwells and long residence
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times may want to check whether iron or manganese solids are accumulating in the
clearwell;
S Customer complaint monitoring can be traced along with color and taste and odor
evaluations to make sure aesthetic quality has not been lost; and
-S The impact of algal blooms on sedimentation and filter performance can be tracked
by measuring turbidity and/or particle counts before and after filtration. Spikes in
turbidity or particle counts may indicate a problem with algal blooms.
Consider Other Tools
In addition to water quality monitoring, there are additional tools available in Chapter 6
to help systems evaluate and improve their current water system in relation to the compliance
issues they may face when modifying their operation or treatment practices. Examples of tools
that can be used when moving the point of chlorination is used as a Stage 2 DBPR compliance
technique include:
• The AwwaRF report "Internal Corrosion of Water Distribution Systems" (AwwaRF
and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot
testing protocols that can be used to evaluate the impacts of pH changes on corrosion
potential. Such pH changes may occur if a utility switches disinfectants;
• The paper "Predicting the Formation of DBFs by the Simulated Distribution System"
published by Koch et al. (1991) can be used to predict the amounts of DBFs that
would form in a distribution system. Key parameters (including chlorine dosage,
incubation temperature, and incubation holding time) are chosen to simulate the
conditions of the treatment plant and the distribution; and
• The second version of "Water Treatment Plant Model" (USEPA 200 Ih) developed by
EPA that assists utilities with implementing various treatment changes while
maintaining adequate disinfection and meeting the requirements of the Stage 2
DBPR.
Readers are encouraged to read through Chapter 6 before making any final compliance decisions.
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Pathogen inactivation by
chlorine depends on pH.
3.4 Decreasing pH
Pathogen inactivation by chlorine is affected by
pH. This is because the germicidal efficiency of
hypochlorous acid (HOC1) is much higher than that of
hypochlorite ion (OC1 ~), and the distribution of chlorine
species between HOC1 and OC1~ is determined by pH. Because HOC1 dominates at low pH
values (< 7.5), chlorination provides more effective disinfection at low pH. At high pH values (>
8.0), OC1 ~ dominates, which causes a decrease in disinfection efficiency.
Public water systems can reduce their pH to increase disinfectant efficiency, enabling
them to lower their disinfectant dose and still achieve the same amount of disinfection, thereby
potentially limiting DBF formation. The system may want to raise the pH again before it enters
the distribution system to avoid corrosion problems within the distribution system. The ease and
desirability of changing pH will depend on the alkalinity and pH of the existing water. Many
other treatment processes can also be affected by changing pH, so careful consideration should
be given before any change is made.
The pH can also impact reactions between chlorine and NOM, resulting in conditions that
favor either TTHMs or HAAS formation. At higher pH, more THMs tend to be formed. Lower
pH tends to favor HAA formation. This information can be used by systems to influence TTHM
or HAAS formation at the plant or in the distribution system by controlling the pH. Systems that
have high TTHM levels but relatively low HAAS may be able to reduce TTHM formation by
lowering pH. However, these systems will need to pay special attention to corrosion issues.
3.4.1 Advantages of Decreasing pH
Advantages to decreasing pH include:
• The same inactivation can be achieved with a lower disinfectant dose or shorter
contact time
• Can reduce formation of some DBFs
Same CT Can Be Achieved with Lower Disinfectant Dose
Virus inactivation studies have shown that 50 percent more contact time is required at pH
7.0 than at pH 6.0 to achieve comparable levels of inactivation with chlorine. These studies also
demonstrated that an increase in pH from 7.0 to 8.8 or 9.0 requires six times the contact time to
achieve the same level of virus inactivation (Gulp and Gulp 1974).
In general, Giardia is the organism that drives the CT required at a water system. Exhibit
3.3 illustrates how pH affects the CT required for 0.5-log inactivation of Giardia lamblia. At a
pH of 7.0, CT required for free chlorine is 19 mg-min/L. For a pH of 6.5, the CT required is 16
mg-min/L. At a contact time of 16 minutes, this corresponds to a reduction in required free
chlorine residual concentration from 1.2 mg/L at a pH of 7.0 to 1.0 mg/L at a pH of 6.5.
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Exhibit 3.3 Effects of pH Changes on CT Required for 0.5-Log Inactivation of
Giardia lamblia
Temperature
10 °C
10 °C
pH
7.0
6.5
CT Required for 0.5 log
inactivation of Giardia
lamblia
19
16
Contact time
(minutes)
16
16
Free Chlorine
Residual needed to
meet CT Required
1.2mg/L
l.Omg/L
Source: Adapted from CT tables in 40 CFR 141.74 National Primary Drinking Water regulations.
Can Reduce DBF Formation
The pH of water can impact the formation of halogenated byproducts (Reckhow and
Singer 1985, Stevens et al. 1989). Exhibit 3.4 compares formation of byproducts at three pH
levels (adapted from Stevens et al., 1989). Note that TTHM show generally lower formation at
the lowest pH level. The formation of HAAs, however, generally increases at lower pH levels.
Exhibit 3.4 Impacts of pH on Formation of DBFs
Byproduct
TTHM
Trichloroacetic Acid
(one of the HAAS)
Dichloroacetic Acid
(one of the HAAS)
Conditions of Formation
Chlorination at pH
5.0
Lower Formation
Similar Formation
Chlorination at pH
7.0
Basis for Comparison
Similar Formation
Chlorination at pH
9.4
Higher Formation
Lower Formation
Similar Formation - perhaps slightly higher at pH 7
Source: adapted from Stevens et al. 1989
Other studies show that limiting pH levels in the distribution system to less than 8.2 may
help to limit TTHM formation (Edwards and Reiber 1997). Four LCR compliance strategy case
studies showed that TTFDVI increases were less than 20 percent if the pH shift implemented for
lead and/or copper corrosion control was near neutral (7.0) to less than 8.2. When the pH was
shifted from near neutral to greater than 8.5, TTHM production increased as much as 40 percent.
At one plant, TTHM increases due to pH adjustment ranged from 2 percent at a pH of 8.1 to 43
percent at a pH of 8.7. HAA production was shown to decrease about 10 percent for all of the
pH increases implemented (Edwards and Reiber 1997).
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3.4.2 Potential Operational and Simultaneous Compliance Issues Associated
with Decreasing pH
Potential issues associated with reducing pH to enhance chlorine disinfection include:
• May increase HAAS formation;
• Can adversely affect treatment plant structures and coatings (i.e., corrosion of
pipes, tanks, etc.);
• Can affect treatment chemistry, sludge dewatering, and inorganic solubility;
• Can cause problems with corrosion control and LCR compliance; and
• If chlorine dose is reduced during primary disinfection, it may be difficult to
maintain secondary disinfection levels throughout the distribution system.
HAAS May Increase
Lower pH conditions may result in higher HAAS concentrations. Reckhow and Singer
(1985) studied humic acid chlorination in laboratory tests and found that trichloracetic acid
concentrations reached a maximum when the water was in the acidic pH range. When pH levels
were increased, trichloroacetic acid concentrations decreased and chloroform (a key component
of TTHM) concentrations increased. Other studies, such as Stevens et al. (1989), have not found
comparable increases in HAAS concentrations when pH levels decreased from neutral to slightly
acidic.
Recommendations for Addressing this Issue
In general, pH values in distribution systems are unlikely to fall in the acidic range given
the requirements of the Lead and Copper Rule and good corrosion control practices. Systems
can conduct simulated distribution system (SDS) studies to simultaneously evaluate impacts of
pH adjustment on both TTHM and HAAS formation. The results of these bench-scale tests can
help identify the optimal pH for balancing the need to control both TTHM and HAAS.
Systems can also evaluate pH fluctuation trends throughout their distribution systems.
For poorly buffered waters, the pH can tend to drift upward as the water reacts with cement-lined
pipes. Increases in pH throughout the distribution system would tend to favor TTHM formation
and reduce HAAS formation.
Adverse Effects on Treatment Plant Materials
If pH levels are lowered to enhance disinfection, components of the treatment plant may
be adversely affected by the acidic conditions. Metal components of the plant may corrode;
plastic or rubber components may deteriorate more quickly; cement/concrete leaching and
deterioration may be exacerbated.
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Recommendations for Addressing this Issue
Systems should evaluate the effects of decreased pH on treatment plant components, such
as pipes and linings. Based on their evaluation, systems should adjust the:
• maintenance schedules,
• materials, or
• point of pH adjustment
so that the chances of leaks, leaching, or equipment failure are minimized.
Adverse Effects on Treatment Chemistry, Inorganics Solubility, Settling, and Sludge Dewatering
Reducing the water pH can cause problems with increased solubility of inorganics, and
may result in increased iron and manganese levels. Lower treated water pH can also result in
recalcification of lime-softened waters, resulting in increased turbidity. Variation of pH levels
can affect treatment chemistry and impact settling and sludge dewatering. System operators
should carefully consider the impacts of pH adjustment before implementing such a significant
change to their treatment process.
Manganese is typically removed from water using direct oxidation/coagulation/filtration
or filter adsorption/oxidation (i.e., green sand). Chlorine is sometimes used for the oxidation
step of this process. A low pH hinders the direct oxidation process because the rate of
manganese oxidation increases as pH increases. The oxidation process for manganese is affected
at a pH below about 6.2 (USEPA 1999h). Therefore, systems using chlorine or potassium
permanganate for manganese oxidation should be aware that, if the pH is reduced before
manganese oxidation, more time may be needed for the manganese to be removed. Manganese
has also been found to accumulate on filter media of systems that use iron coagulants. This
manganese layer can be released if pH and disinfectant conditions change across the filter.
Manganese release was found to increase at pH's as high as 7 and to be rapid at pH 6 (Wert et al.
2005).
The minimum solubility of aluminum occurs at a pH of 6.2 to 6.5. Those water systems
that use alum as a coagulant and operate at a pH of less than 6.0 that do not increase their pH
before filtration may be impacted by the solubility of aluminum at this low pH. If the pH is not
adjusted before filtration, aluminum carryover problems may result.
Recommendations for Addressing this Issue
Systems with high manganese levels that lower the pH prior to filtration may want to
consider using an oxidant that is less pH dependent to oxidize manganese, such as ozone.
Alternatively, a system could choose to lower the pH after oxidation and filtration. Maintaining
a chlorine residual across the filter should prevent manganese from being released in systems
using iron coagulants.
Systems using alum as a coagulant can adjust pH to greater than 6.5 before the filters to
avoid aluminum passing into the distribution system.
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Corrosion Control andLCR Problems
A lower pH in the distribution system can increase corrosion of cement linings and iron
pipe. It can also favor corrosion of lead and copper plumbing, causing LCR compliance
problems. Corrosion of unlined cast iron water mains can favor microbial regrowth, which can
affect TCR compliance.
A drop of one pH unit may cause
the desorption of some metal ions,
or cause significant dissolution of
carbonate or oxyhydroxide
mineral scales on lead, copper, iron
or other pipe surfaces (Shock
2005).
Any changes in the pH levels historically
maintained in a distribution system can disrupt
films and scales that have accumulated on natural
corrosion surfaces. These films and scales have
formed over long periods of time and may be
helping to passivate the corrosion process from
further development. A decrease of one pH unit
may cause the desorption of some metal ions, or
cause significant dissolution of carbonate or
oxyhydroxide mineral scales on lead, copper, iron or other pipe surfaces (Shock 2005).
Although the disruption of films or scales in the distribution system may not result in a direct
violation of either the DBF or microbial rules, the disruption could cause aesthetic problems or
the release of microbes. Disruption of scale can also cause maintenance problems in utility
facilities such as tanks, valves, and pumps, as well as in customer sprinkler systems and
commercial facilities.
Recommendations for Addressing this Issue
If pH is lowered during disinfection, systems with pipe materials susceptible to corrosion
should consider adjusting pH upward and possibly adjusting alkalinity before the water enters
the distribution system to reduce corrosion of pipe materials. If finished water pH is reduced, the
system should consider other corrosion control strategies.
Water systems should carefully
research the implications of
using a corrosion inhibitor before
adding it as a treatment step.
Systems can control corrosion by optimizing pH,
alkalinity, and dissolved inorganic carbon (DIG).
Another alternative is to add a corrosion inhibitor that is
phosphate- or silica-based to form a protective coating
on pipes. As inhibitor effectiveness is dependent on
pipe material and water quality, any system considering
using a corrosion inhibitor to offset the effects of lower pH should carefully research the options.
Some utilities, however, have elected not to use phosphate-based corrosion inhibitors because the
publicly owned treatment works (POTW) receiving the wastewater has phosphorus limits in their
national pollutant discharge elimination system (NPDES) and sludge disposal permits.
Regardless of the type of corrosion treatment
used, it should be tested before it is introduced, if
possible. Pilot testing is discussed in more detail in
Section 6.3.5 of this manual. Large systems should
have completed corrosion control studies, as required
by the LCR. Smaller water systems may have
conducted studies if required by the state. Any
Appendix D provides additional
guidance for systems evaluating
their corrosion control options
and information on proper
piloting procedures.
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system that subsequently changes their treatment must notify the state and may be required to
conduct a new corrosion control study. In any event, LCR corrosion control studies should be
used as a starting point to assess the impacts of changes in distribution system water quality on
corrosion and LCR compliance and determine the best corrosion control treatment strategy.
Appendix D provides additional guidance for systems evaluating their corrosion control options
and information on proper testing procedures.
Reduced Disinfectant Residual Concentration
Systems that are considering lowering their disinfectant dose to take advantage of
additional CT credit at a lower pH should consider impacts on maintaining the desired
disinfectant residual level throughout the distribution system. A lower disinfectant dose may
mean a lower disinfectant residual concentration leaving the treatment plant if the system does
not have a chlorine dose point after the clearwells.
Recommendations for Addressing this Issue
Additional chlorine will be needed prior to entry to the distribution system, or through
booster disinfection, to account for the decrease in chlorine during primary disinfection.
3.4.3 Recommendations for Gathering More Information
Read the Case Study
For more information on simultaneous compliance issues associated with modifying pH,
see Case Study #2 Modifying pH During Chlorination starting on page B-l 1 of Appendix B.
This case study describes how one PWS used pH depression via carbon dioxide injection ahead
of the flocculation basins to reduce DBFs and DBF precursors. The system was also able to
increase coagulation efficiency, increase CT throughout the treatment plant (allowing for
reduced chlorine injection), and increase and stabilize pH levels in the distribution system by
increasing the buffering capacity following caustic soda addition. Their greatest operation issue
was a need for a pressurized solution feed to solubilize CO2.
See Additional References
Sections 7.1.2, 7.1.3, and 7.17 in Chapter 7 contain technical references associated with
DBF formation, corrosion, and chlorination, including references on how each process is
affected by pH. General water treatment references in Section 7.1.1 can also provide useful
information.
Consider Additional Monitoring
The following are some suggestions for additional monitoring that may benefit water
systems that are reducing their pH during chlorination:
•S If alum is used as a coagulant and pH is not adjusted back up before filtration,
systems should test periodically for aluminum in the finished water;
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S Systems should perform routine pH and alkalinity monitoring at significant locations
throughout the treatment plant, especially after corrosion control chemicals have been
added;
S Where it may be a problem, systems should perform periodic monitoring of iron and
manganese in the finished water;
S Systems can perform additional HPC and total coliform monitoring in the distribution
system near locations where there is reason to believe that scale may have been
dislodged; and
S Systems can track customer complaints, color, and turbidity in the distribution system
if there is reason to believe that changes in pH can affect scales and films.
The purpose of these monitoring suggestions is specifically to address and prevent potential
simultaneous compliance issues.
Consider Other Tools
In addition to water quality monitoring, there are additional tools available in Chapter 6
to help systems evaluate and improve their current water system in relation to the compliance
issues they may face when modifying their operation or treatment practices. Examples of tools
that can be used when modifying pH during chlorination is used for Stage 2 DBPR compliance
include:
• The SDS and material-specific (MS-SDS) procedures described by Koch et al (1991)
and Brereton and Mavinic (2002), respectively, which describe bench-scale and pilot-
scale tests that can be used to evaluate DBF formation under varying chlorine,
temperature, and pH conditions;
• The AwwaRF report "Internal Corrosion of Water Distribution System" (AwwaRF
and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot
testing protocols that can be used to evaluate changes in corrosion potential due to pH
changes;
• The AwwaRF report "Optimizing Corrosion Control in Water Distribution Systems"
(Duranceau, et. al 2004) which provides techniques for instantaneous corrosion
monitoring;
• The "Guidance Manual for Monitoring Distribution System Water Quality"
(Kirmeyer et al. 2002) which can be used to assist water utilities in implementing a
distribution system water quality data collection and analysis program; and
• The second version of "Water Treatment Plant Model" (USEPA 200 Ih) developed by
EPA that assists utilities to implement various treatment changes while maintaining
adequate disinfection and meeting the requirements of Stage 2 DBPR.
Readers are encouraged to read through Chapter 6 before making any final compliance decisions.
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3.5 Reducing Chlorine Dose under Warm Water Conditions
In general, as temperature increases, chlorine reaction kinetics increase. The increased
kinetics mean that disinfection effectiveness will improve, but it also means that TTHM and
HAAS will form more quickly. This section discusses the advantages and disadvantages of
reducing chlorine residual concentration at the treatment plant during periods of warm water
temperature.
3.5.1 Advantages of Reducing Chlorine Dose under Warm Water Conditions
By reducing the chlorine residual at the treatment plant during warm water conditions,
systems can achieve:
• Comparable pathogen inactivation with less chlorine
• Reduction in TTHM and HAAS formation
Comparable Pathogen Inactivation with Less Chlorine
Systems that use the same chlorine dose throughout the year at their plant to meet CT
requirements may be getting significantly higher log inactivation for Giardia and viruses in the
summer months than in winter months. This is especially true in temperate regions with seasonal
changes in source water temperature. Exhibit 3.5 shows how water temperature affects the
amount of CT required to achieve 0.5-log Giardia lamblia inactivation. Note, for example, how
the CT required at 5.0° C and a free chlorine residual of 1.0 mg/L is 25 mg-min/L. But when the
water temperature increases to 20° C and a free chlorine residual of 1.0 mg/L is used, the CT
required for 3-log Giardia lamblia inactivation decreases to 9 mg-min/L. Systems may be able
to provide sufficient CT in the summer months using a lower concentration of free chlorine than
the concentration they are using during the winter to provide the same pathogen protection.
Systems should
ensure that they
continue to meet CT
requirements
Disinfectant residual should not be lowered below the
point of compliance with the CT requirements dictated by the
SWTR (USEPA 1989). Systems should carefully evaluate their
disinfection profiles to ensure that they meet benchmarking
requirements and refer to guidance provided in The Disinfection
Profiling and Benchmarking Guidance Manual (USEPA 1999a).
Reduction in TTHM and HAAS Formation
By reducing the chlorine residual at the treatment plant when water temperatures
increase, systems may be able to reduce the formation of TTHM and HAAS. Krasner et al.
(1990) found that the median TTHM concentrations in 35 systems were highest for those
systems with the highest water temperature.
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Exhibit 3.5 Required CTfor 0.5-Log Inactivation of Giardia lamblia by Free
Chlorine at pH 7.0
Free chlorine residual (mg/L)
<0.4
0.6
0.8
1.0
0.5° C
33
33
34
35
5.0° C
23
24
24
25
10.0° C
17
18
18
19
15.0° C
12
12
12
13
20° C
9
9
9
9
25° C
6
6
6
6
Adapted from 40 CFR Part 141 National Primary Drinking Water Regulations § 141.74
3.5.2 Potential Operational and Simultaneous Compliance Issues Associated
with Reducing Chlorine Dose under Warm Water Conditions
Some potential issues associated with reducing the chlorine residual concentration at the
plant under warm temperature conditions are:
• Higher disinfectant residual needed for addressing seasonal pathogens (e.g.,
water is used for recreational purposes, flowing waters with permitted
wastewater discharges when flows are low);
• Distribution system impacts if finished water chlorine concentration is decreased.
Seasonal Variability of Pathogen Concentrations in the Source Water
Pathogen concentrations may increase in some surface water sources during the summer
months. Concentrations of viruses and enteric bacteria are of particular concern, especially if the
source water is also used for recreational activity. Other pathogens such as Cryptosporidium
have been found to peak during spring runoff.
Recommendations for Addressing this Issue
Systems should evaluate uses of their source water and examine historical data to
determine if there is a trend in pathogen occurrence in the warmer months. Systems should also
consider consulting with their states to determine if others have collected data for the same
source. Many systems will soon have Cryptosporidium and/or E. coli data available for their
source as a result of the LT2ESWTR source water monitoring requirements. If data are not
available, systems may want to collect surveillance fecal coliform or E. coli samples at their
intake to track whether they should be concerned about increased microbial risk.
Distribution System Issues if Chlorine Residual in Finished Water is Decreased
In cases where systems do not add chlorine again after primary disinfection, reducing the
chlorine dose at the treatment plant during warmer months may result in lower finished water
chlorine residual concentrations. Lower finished water residual levels combined with the faster
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decay rate of chlorine in the warmer months may make it difficult for some systems to meet the
SWTR requirement of maintaining a detectable residual throughout the distribution system.
Distribution systems are also more susceptible to microbial growth during periods of
warmer water temperature. Studies have shown that increased water temperatures and
corresponding increases in organic matter can enhance coliform re-growth in the distribution
system (LeChevallier et al. 1996).
A reduction in chlorine concentration will generally result in a lower oxidation reduction
potential (ORP) of the water. ORP is a fundamental characteristic of the water that influences
corrosion reactions on metal pipes. In cases where lead oxide (PbO2) compounds have formed
on lead service lines, reductions in ORP can cause dissolution of PbO2 under certain conditions
(Lytle and Schock 2005; Schock and Giani 2004). Reductions in ORP can also cause manganese
deposits on pipes to dissolve, potentially depositing again on plumbing fixtures and staining
laundry.
Recommendations for Addressing this Issue
If systems are having difficulty maintaining their chlorine residual in the distribution
system to meet SWTR requirements, control microbial growth, and ensure compliance with the
TCR, they can consider using the distribution system BMPs identified in section 3.2 to reduce
disinfectant decay (such as flushing) and to reduce water age (such as improving mixing in
storage facilities and installing blowoffs). Booster disinfection may also be a good strategy for
maintaining a residual in remote areas of the distribution system.
If reducing the chlorine dose at the treatment plant during periods of warm water
temperatures will result in significantly lower chlorine residual in the finished water, systems
should consider using various tools and/or monitoring to determine how the change could impact
corrosion of metals in the distribution system. Systems could conduct additional monitoring
determine the range of ORP levels in the distribution system prior to the change. Appendix D
describes various tools that can be used to assess the potential impact of treatment changes on
LCR compliance. Systems should also carefully monitor customer complaints to determine if
manganese deposits have become a problem.
3.5.3 Recommendations for Gathering More Information
See Additional References
Readers can turn to Sections 7.1.1,7.1.4, and 7.1.17 in Chapter 7 for general references
associated with disinfection, technical references related to distribution system management, and
technical references related to chlorination.
Consider Additional Monitoring
The following are some suggestions for additional monitoring that may benefit water
systems that are reducing their chlorine dose:
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•/
Routine raw and finished water monitoring for E. coll and total coliform, especially
during the periods when the system is reducing its chlorine dose;
Increased chlorine residual measurements throughout the distribution system;
Increased HFC and total coliform surveillance monitoring in the distribution system;
Chlorine demand monitoring prior to chlorine addition for secondary disinfection to
make sure stable water is sent into the distribution system; and
Inspection of distribution system pipe scales (including service lines and domestic
plumbing) to see if reductions in disinfectant residual and/or lower redox potential
mav name a nrnhlematir, chancre in scale intecritv anH metal release
•/
J_/AL*AAAL/AAA£^y \,\U \3\J\J AA_ A \^\J-L+\^ LA V/AAtJ AAA VJ.A tJA AAA. \J\J LU.AA I A \J tJ A VJ. L* CI.A U.J.J.U7 V/A AV/VVWA A'
may cause a problematic change in scale integrity and metal release.
The purpose of these monitoring suggestions is specifically to address and prevent potential
simultaneous compliance issues.
Consider Other Tools
In addition to water quality monitoring, there are additional tools available in Chapter 6
to help systems evaluate and improve their current water system in relation to the compliance
issues they may face when modifying their operation or treatment practices. Examples of tools
that can be used when varying the chlorine dosage is used for Stage 2 DBPR compliance include:
• The Disinfection Profiling and Benchmarkng Guidance Manual (USEP A 1999a)
describes how systems can develop a disinfection profile and identify their
benchmark. It also provides guidance on what constitutes a significant change in
disinfection practices.
• The Guidance Manual for Monitoring Distribution System Water Quality (Kirmeyer
et al. 2002) which can be used to assist water utilities in implementing a distribution
system water quality data collection and analysis program;
• The Standard Method 2350 (Oxidant Demand/Requirement) (APHA 1998) that
provides step-by-step instructions for the determination of chlorine demand during
various water quality conditions; and
• The paper "Predicting the Formation of DBFs by the Simulated Distribution System"
(Koch et al. 1991) that can be used to closely monitor and predict changes in DBF
formation in the distribution system due to frequent chlorine dose changes.
Readers are encouraged to read through Chapter 6 before making any final compliance decisions.
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3.6 Modifying Pre-sedimentation Basin Operations
Pre-sedimentation basins are basins placed before the rapid
mix chamber and the flocculation basins. Their purpose is to allow
large particles and debris to settle out before the main coagulation
process and before any disinfectant is added. Pre-sedimentation
basins provide a buffer to turbidity fluctuations and can lower DBF
precursors entering the plant. Existing basins can be modified to
increase Cryptosporidium removal by adding a coagulant or
increasing residence time.
3.6.1 Advantages of Modifying Pre-sedimentation Basin Operations
The advantages of pre-sedimentation basins include:
• Can lower DBF precursors prior to the addition of disinfectants;
• Can possibly achieve 0.5 log of Cryptosporidium removal credit under the
LT2ESWTR; and
• Reduce solids loading and improve stability of water quality for downstream
treatment processes.
Lower DBF Precursor Concentrations
By modifying pre-sedimentation basins, systems can remove additional DBF precursors
and decrease TTHM and HAAS formation. Pre-sedimentation basins are especially useful to
systems with high levels of solids in their raw water _
or highly fluctuating turbidity. Addition of a
coagulant in the pre-sedimentation basin may
increase the removal of DBF precursors.
Cryptosporidium Removal Credit
Addition of a coagulant in the
pre-sedimentation basin may
increase the removal of DBP
precursors.
Systems with pre-sedimentation basins can receive 0.5-log removal credit for
Cryptosporidium. In order to get the credit for the pre-sedimentation basin, all of the plant's
water must pass through the basin and a coagulant must be added whenever the basin is
operating. Alternatively, systems can conduct their LT2ESWTR monitoring for
Cryptosporidium after the pre-sedimentation basin to determine their treatment bin. If a system
monitors for bin selection after the pre-sedimentation basin, it cannot get the 0.5 log
Cryptosporidium removal credit for the basin. These systems may, however, end up in a lower
treatment bin due to Cryptosporidium removal in the pre-sedimentation basin. See the
LT2ESWTR Microbial Toolbox Guidance Manual (USEPA N.d.e) for additional information on
receiving the removal credit.
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Reduce solids loading and improve water stability
Pre-sedimentation basins allow extra time before the water enters the treatment process.
This will allow particles suspended by flow to settle out before entering the main treatment train.
It will also help to dampen turbidity and particle concentration fluctuations caused by storm
events. This will reduce solids loading and fluctuations on downstream processes which can
improve process performance.
3.6.2 Potential Operational and Simultaneous Compliance Issues Associated
with Modifying Pre-sedimentation Basin Operations
Potential issues associated with using pre-sedimentation basins include:
• Algal growth in pre-sedimentation basins can increase DBF precursors
• Removal of settled solids can be difficult
Algal Growth
Algae can grow in uncovered pre-sedimentation basins that are not treated with a
disinfectant. The algae can add NOM to the water, increasing the chlorine demand, and can
negate DBF precursor removal obtained during pre-sedimentation. Algae are also known to
produce taste and odor compounds and interfere with flocculation/sedimentation and filtration.
Recommendations for Addressing this Issue
There are several ways to prevent algae growth in pre-sedimentation basins. Potassium
permanganate addition has been used with mixed success in efforts to stop algae growth and
control resulting tastes and odors. Covering basins to block ultraviolet (UV) light will also
prevent algae growth. Although this can be a more expensive solution, floating covers are
available that can provide a lower-cost alternative.
Removal of Settled Solids
Solids should be removed on
a regular basis to prevent
interference with plant
performance and compliance
with regulatory requirements.
Solids that accumulate in the bottom of pre-
sedimentation basins should be removed
periodically. This is especially true when a
coagulant is added. If a coagulant is not added,
systems may be able to manage solids with periodic
manual removal. Systems may not be able to use a coagulant if they cannot add solids removal
equipment to the basin. Although it presents additional costs to the plant, solids removal should
not interfere with plant production if it is done on a regular basis.
Recommendations for Addressing this Issue
If a coagulant is not used, systems should consider using two basins, taking one off-line
while the other is being cleaned to avoid stirring up sediment and allowing it to enter the plant.
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Solids should be removed on a regular basis to prevent interference with plant performance and
compliance with regulatory requirements. Solids can be removed in various ways such as using
a sloped floor and center drain or specially designed vacuums or pumps. Removal can be
accomplished manually by regular cleaning or dredging.
3.6.3 Recommendations for Gathering More Information
Read the Case Study
For more information on simultaneous compliance issues associated with pre-
sedimentation basins and how to address them, see Case Study #3 Pre-sedimentation starting on
page B-19 of Appendix B. This case study describes how one PWS was able to monitor effluent
from their pre-sedimentation basins to determine their Cryptosporidium bin classification for the
LT2ESWTR. Operational issues include problems with algae blooms, which the system was
typically able to control by adding potassium permanganate to the basins.
See Additional References
Readers can turn to Section 7.1.1 in Chapter 7 for general technical references associated
with water treatment. The final LT2ESWTR Microbial Toolbox Guidance Manual (USEPA
N.d.e) provides additional information on pre-sedimentation.
Consider Additional Monitoring
The following are suggestions for additional monitoring that may benefit water systems using
pre-sedimentation:
-S Turbidity measurements as water leaves the pre-sedimentation basin and enters the
treatment plant, in order to detect impacts of sediment buildup or short-circuiting on
water quality entering the plant; and
-S If algae growth is a problem, routine algal counts, chlorophyll a measurements, or
Secchi disk depth readings as feasible, to guide algae management efforts.
The purpose of these monitoring suggestions is specifically to address and prevent potential
simultaneous compliance issues.
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3.7 Enhanced Coagulation
One way to remove NOM is to practice enhanced
coagulation. Enhanced coagulation has been shown to be an
effective strategy for reduction of DBF precursors for many
systems (Krasner and Amy 1995). Reduction of pH to between 5
and 6 and/or use of higher coagulant doses has been found
effective in reducing TOC to required levels (Krasner and Amy
1995). Enhanced coagulation can include one or more of the
following operational changes:
• Increasing coagulant dose
• Changing coagulant
• Adjusting pH (using acid to lower the pH as low as 5.5)
• Improving mixing or applying moderate dosage of an oxidant
• Adding a polymer
As one part of the treatment process is modified, PWSs should consider the impacts on
subsequent processes and within the distribution system. Systems considering whether enhanced
coagulation may be an effective way to reduce DBFs should refer to the Guidance Manual for
Enhanced Coagulation and Precipitative Softening (USEPA 1999h).
This section discusses the advantages and disadvantages of enhanced coagulation, and
provides recommendations for how systems may be able to address and minimize the
disadvantages.
3.7.1 Advantages of Enhanced Coagulation
Some advantages of enhanced coagulation include:
• May improve disinfection effectiveness
• Can reduce DBF formation
• Can reduce bromate formation
• Can enhance arsenic and radionuclide removal
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Improved Disinfection Effectiveness
All public water systems with a surface water source or a ground water source under the
direct influence of surface water must achieve a 3.0 log Giardia removal/inactivation and 4.0 log
virus removal/inactivation. Enhanced coagulation can improve disinfection effectiveness in
three ways:
• Lower the pH during disinfection to improve chlorine effectiveness
• Reduce disinfectant demand
• Remove particles to which pathogens are attached
The pH may be suppressed artificially using an acid or may be the result of heavy alum or ferric
coagulant doses.
Chlorine is pH-sensitive, being more effective at low pH values (see Section 3.4 for a
more complete discussion of chlorine sensitivity to pH). Therefore, a decrease in pH results in
greater inactivation of Giardia and viruses. For example, a system with a 1.0 mg/L chlorine
residual decreasing its pH from 7.0 to 6.5 at a temperature of 10°C would lower its CT
requirement for 3 log Giardia inactivation from 112 mg-min/L to 94 mg-min/L. Ozone also
exhibits increased performance at lower pH values (Carlson et al. 2000). Conversely, chlorine
dioxide can be less effective at low pH values and less monochloramine is formed at lower pH.
The removal of NOM through enhanced coagulation may allow increased disinfectant
efficiency by decreasing the demand on the disinfectants exerted by organics (Carlson et al.
2000). The amount of NOM removed will vary depending on the pH, coagulant, coagulant dose,
and NOM properties. The amount of NOM removal for a given system can be determined using
jar tests. Alternatively, computer models are available that can predict organic removal given the
pH, coagulant dose, and organic properties (Edwards 1997). For a system to realize this benefit,
the system should inject the disinfectant at a location in the treatment process where NOM
removal has been achieved. This operational scenario may allow the system, in consultation
with its regulatory agency, to reduce the amount of disinfectant used compared to dosages
required prior to practicing enhanced coagulation. A reduction in the amount of disinfectant
applied should result in fewer DBFs being formed. The system should, however, ensure that the
necessary microbial inactivation is maintained at all times by measuring:
• The disinfectant residual
• Flow, temperature, and pH
• Calculating the resulting inactivation contact times and CTs being achieved
Increased removal of organic particles obtained using enhanced coagulation can have the
added benefit of removing additional microbial pathogens. For example, States et al. (2002)
found that enhanced coagulation with filtration could achieve 5.0 log removal of
Cryptosporidium compared to an estimated 2.0 log removal by filtration without coagulation.
Reduced DBF Formation
Enhanced coagulation improves the removal of DBF precursors in a conventional water
treatment plant. The removal of TOC (a surrogate measure of NOM) by coagulation has been
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demonstrated in several laboratory research, pilot demonstrations, and full-scale studies
(Chowdhury et al. 1997, Edwards 1997). Removal of TOC can result in a decrease in TTHM
and HAAS formation. In fact, the Stage 1 D/DBPR uses TOC to define enhanced coagulation
for DBF precursor removal regulatory requirements. The actual reduction in TOC can vary
widely. Systems can obtain a better idea of the removal they can obtain by using jar tests.
Reduced pH, which is usually characteristic of enhanced coagulation, has also been
demonstrated to result in a reduction in formation of chloroform (Singer 1999). A more detailed
discussion of this topic is provided in Section 3.4.
Reduced Brornate Formation
The reduction of pH that is commonly practiced as part of enhanced coagulation can
result in better control of bromate formation for those systems using ozone. Williams et al.
(2003) indicated that a pH of about 6.5 provided effective reduction of bromate formation. The
effectiveness of bromate control at lower pH values depends on the source water, particularly its
alkalinity.
Arsenic and Radionuclide Removal
Compliance with the new arsenic maximum contaminant level (MCL) of 0.010 mg/L
may require systems to consider treatment modifications for improved arsenic removal. Some
systems may realize improved arsenic removal by using a ferric coagulant as part of the
enhanced coagulation process. Scott et al (1995) observed that arsenate (As(V)) removal was in
the range of 80 to 95 percent for a ferric coagulant dose ranging from 3 to 10 mg/L. Alum
coagulation has been shown to remove arsenic, but at higher doses (up to 20 mg/L) Removal of
arsenite (As(III)) is much less efficient than As(V), though iron coagulants are still more
effective at removing As(III) than alum coagulants (Hering et al. 1996; Edwards 1997).
Modified coagulation is identified by EPA as a Best Available Technology (BAT) for the
Arsenic Rule.
Enhanced coagulation may also provide better radionuclide removal since radionuclides,
such as uranium, have been shown to be removed by coagulation/filtration (Sorg 1988). Systems
will want to understand fully their requirements for disposal of residuals containing
radionuclides and check with their State or Primacy Agency for instructions on special handling
or disposal of residuals containing radionuclides.
3.7.2 Potential Operational and Simultaneous Compliance Issues Associated
with Enhanced Coagulation
Potential issues associated with enhanced coagulation include:
• Adverse impacts to filtration process
• Corrosion concerns
• Increased concentrations of inorganics in the finished water
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• Additional issues with residual disposal
This section discusses these issues briefly and provides suggestions for reducing their impacts.
Adverse Impacts to Filtration Process
In most cases, lowering the pH and/or increasing coagulant feed will result in lowering
turbidity in the finished water. However, lower pH levels can sometimes lead to the formation of
a less dense, more fragile floe. This type of floe can carry over from the clarifier and may result
in shorter filter run times or premature filter breakthrough (Singer 1999). A lower pH and higher
coagulant dose may also result in restabilization of particles. These conditions can create upsets
in solids blanket-type clarifiers (Carlson et al. 2000).
Premature filter breakthrough as a result of higher particle loading to the filter could
result in shorter filter runs or, if a system does not adjust its operations in response to the higher
particle loading, the system might not meet the turbidity limits established by the IESWTR and
LT1ESWTR. This may also trigger individual filter follow-up actions as required by IESWTR
and LTIESWTR. Conversely, enhanced coagulation may have a positive effect on subsequent
treatment steps, resulting in lower finished water turbidity, potentially longer filter runs, and
better compliance with effluent turbidity limits.
Recommendations for Addressing this Issue
Systems may want to pilot test different coagulants to identify the coagulant type and
dose that produces the most stable, settleable floe. Lovins et al. (2003) found that ferric sulfate
produced a larger, more durable and more settleable floe relative to alum in Peace River water, a
high DOC water, at a pH of around 7.5.
Systems should consult the Enhanced Coagulation and Enhanced Precipitative Softening
Guidance Manual (USEPA 1999h) for recommendations on how to maintain low turbidity while
performing enhanced coagulation.
Corrosion Concerns
Corrosion control within the distribution system and water treatment plant can be affected
by a change in pH, change in the chloride to sulfate ratio, change in organics concentration, or a
significant change in the alkalinity of the finished water (Carlson et al. 2000). Any of these
conditions can occur as a result of enhanced coagulation and can potentially create compliance
issues with the LCR or result in degradation of plant facilities.
Enhanced coagulation lowers TOC. Changes in TOC have been found to have differing
impacts on corrosion. Schock et al. (1996) found that in some cases, NOM can form soluble
complexes with lead which can increase corrosion. In other cases, NOM was found to coat the
pipes and lower corrosion rates. Edwards et al. (1996) have reported similar results for copper
corrosion. Edwards et al. (2004) found that lower TOC in combination with higher aluminum
may cause pinholes leaks in copper piping.
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Enhanced coagulation can lower alkalinity. The effect of an alkalinity change depends
on the initial alkalinity; for water with moderate to low alkalinity, a decrease in alkalinity can
increase corrosion. Lower alkalinity can also damage concrete in pipes or in basins and
reservoirs. Systems are encouraged to maintain a minimum alkalinity of 10 to 20 mg/L as
calcium carbonate. If the initial alkalinity is high, however, a decrease may be beneficial since a
decrease in alkalinity can also decrease copper corrosion rates.
Enhanced coagulation lowers pH. Lower pH generally increases corrosion rates.
Changing distribution system pH can also alter the condition of pre-existing scale. The lower the
initial pH, the smaller the pH change needed to affect the corrosion rate. At an initial pH of 7, a
pH change of 0.2 can affect corrosion, while with an initial pH of 9 it takes a pH change of over
0.5 to significantly affect corrosion (AWWA 2005a). Softened scale can break off and release
any material contained in the scale into the distribution system water.
Lower pH can also have adverse impacts within the treatment plant. Cement can degrade
in acidic conditions. Metals in pipes and pumps may also be susceptible to corrosion.
If aluminum coagulants are used and filtration is not optimized, efforts to perform
enhanced coagulation may result in increased aluminum concentrations. Aluminum can increase
corrosion of lead and copper, though it will decrease corrosion of copper byproducts.
The increased use of coagulants in enhanced coagulation will raise the concentration of
the anion, either sulfate or chloride, and will affect the chloride to sulfate ration. A low chloride
to sulfate ratio has been shown to decrease corrosion rates (Edwards et al.1999).
Recommendations for Addressing this Issue
Systems should consider adjusting their pH upward before the water enters the
distribution system in order to reduce corrosion of pipe materials. Systems will want to identify
the optimum pH within the distribution system that
enables compliance with the LCR and does not result
Water systems should carefully
research the implications of
using a corrosion inhibitor before
adding it as a treatment step.
in substantial increases in DBF levels.
There are several options available to increase
pH. These include addition of lime, caustic soda, soda
ash, and sodium bicarbonate. Another possible method of increasing pH is to filter using
limestone or other alkaline media. Each of these techniques has advantages and disadvantages
that will depend on the water quality of the water being adjusted and the distribution system
materials that must be protected. For example, soda ash raises alkalinity as well as pH. The
increased alkalinity can cause increased corrosion of some materials (Kirmeyer et al. 2002). The
reference tools listed at the end of this section provide more guidance on proper selection of pH
adjustment techniques.
If the system cannot readjust the pH to a high enough level using caustic to prevent
corrosion, it can consider adding a corrosion inhibitor (i.e., a substance that is phosphate- or
silica-based) to the finished water to form a protective coating on the pipes.
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Water systems should carefully research the implications of using a corrosion inhibitor
before adding it as a treatment step. Some utilities have elected not to use phosphate-based
corrosion inhibitors because the POTW receiving the wastewater violated phosphorus limits in
their disposal permits. Zinc toxicity to wastewater treatment biota can also be a concern. Lime
addition can potentially cause turbidity problems if the dosing and mixing are not done properly.
Conversely, research has shown that corrosion control often has the added benefit of controlling
biological growth in the distribution system, which can lead to improved compliance with the
TCR.
Regardless of the type of corrosion inhibitor used, it should be carefully pilot-tested
before it is introduced. Large water systems were required to conduct corrosion control studies
under the LCR. Smaller systems may have conducted studies if required by the state. Any
system that subsequently changes their treatment must notify the state and may be required to
conduct a new corrosion control study. In any event, LCR corrosion control studies should be
used as a starting point to assess the impacts of changes in distribution system water quality on
corrosion and LCR compliance and determine the best corrosion control treatment strategy.
Appendices C and D provide additional guidelines for systems evaluating their corrosion control
options and information on proper piloting procedures.
Systems should also monitor inside the plant for signs of corrosion of concrete or metal.
If corrosion is noticed, corrosion may be prevented by applying an epoxy coating. For metals
such as pipes and pumps or metal rebar in concrete structures, using a sacrificial anode is an
option in addition to epoxy coatings. Exterior fittings in buildings should be painted to reduce
corrosion. Finally, materials compatible with the anticipated pH and water quality in the plant
should be specified when designing new processes.
Increased Inorganics in Finished Water
Enhanced coagulation can cause an increase in inorganics, such as manganese,
aluminum, sulfate, chloride, and sodium in the finished water. The low pH that frequently
results from enhanced coagulation reduces the oxidation rate of manganese from the dissolved
state (Mn2+) to the solid form (MnO2) that allows it to be removed during sedimentation and
filtration. Ideally, manganese is completely oxidized before the coagulation step, and enhanced
coagulation should not deter manganese removal. Systems should note, however, that even very
low concentrations of manganese (e.g., 0.05 mg/L) in the finished water could result in aesthetic
problems.
Manganese may also be present in concentrations above the secondary standard of 0.05
mg/L if high dosages of ferric coagulants are used (Carlson et al. 2000). Ferric chloride and
ferric sulfate coagulants can contain relatively high concentrations of manganese. If a water
system switches from low doses of ferric or alum to high doses of ferric, the coagulant itself may
significantly increase the amount of dissolved manganese in the water.
The presence of high concentrations of sulfate or chloride may affect the corrosivity of
the water (Carlson et al. 2000). The mass ratio of chloride to sulfate can also affect the
corrosivity of the water. Edwards et al. (1999) found that of 24 utilities surveyed, none of the
utilities with a chloride to sulfate ratio of less than 0.58 exceeded the lead action level, while 64
percent of utilities with a ratio greater than 0.58 exceeded the lead action level.
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Increased aluminum in the distribution system may result when high alum dosages are
used in an effort to perform enhanced coagulation. Increased aluminum can lead to aesthetic
problems, such as solids precipitation, in the distribution system (Carlson et al. 2000). Increased
alum can be kept from passing through filters by addition of filter aids and more frequent
backwashing. More frequent backwashing, however, has costs and other implications.
Recommendations for Addressing this Issue
System operators should consider their source water specifically when making choices
about coagulant use. Systems should jar test and, ideally, pilot test under different water quality
conditions the coagulants that they are considering before making full-scale coagulant treatment
changes. NSF and manufacturer recommendations should be followed in coagulant dosing.
Specifications for coagulants and other treatment chemicals should also specify allowable
concentrations of trace contaminants. Section 6.3 describes some ways systems can test their
water to determine which coagulant is best suited for their water quality and particular treatment
needs. Systems with a high chloride to sulfate ratio may be able to mitigate corrosion by
switching from a chloride-based coagulant to a sulfate-based coagulant.
Residuals Handling
Because more coagulant is added and more organics are being removed, enhanced
coagulation will likely result in the production of more waste residuals. The conditions for
existing disposal of water treatment plant (WTP) sludge should be reviewed and even
renegotiated, and increased costs of waste disposal should be factored into a system's decision.
If the source water has high concentrations of hazardous contaminants such as arsenic,
the waste residuals may concentrate these contaminants to the extent that the waste is considered
unfit for disposal in a sanitary landfill. Some states have stricter limits on toxics concentrations
in waste residuals disposed of in sanitary landfills, and exceeding any of those limits could cause
the waste to be classified as hazardous. In addition, some states have additional disposal
requirements for residuals that have been characterized as technologically enhanced naturally
occurring radioactive material (TENORM) that can further complicate disposal.
Recommendations for Addressing this Issue
Systems will likely experience higher costs with managing an increased residual load.
Depending on how residuals are managed, additional facilities may need to be constructed or
new permits may be necessary. Aluminum is toxic to aquatic life, so increased alum use may
result in limitations on the discharge of the residual stream to surface water bodies.
Systems should properly analyze the sludge that results from enhanced coagulation for
increased metals and other contaminants that may create issues with final sludge disposal. The
regulatory agency should be consulted regarding disposal of residuals if hazardous chemicals are
concentrated in the residuals. EPA has recently released A Regulator's Guide to the
Management of Radioactive Residuals from Drinking Water Treatment Technologies, (USEPA
2005c) which deals with the issue of radioactive compounds concentrated in residuals.
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Typically, ferric sulfate sludges are more easily dewatered as compared to alum sludges
(Thompson and Paulson 1998).
3.7.3 Recommendations for Gathering More Information
Read the Case Studies
Four case studies in Appendix B describe simultaneous compliance challenges faced by
utilities using enhanced coagulation.
Case Study #1 - Improving and Optimizing Current Operations starting on page B-5 of
Appendix B describes how two small PWSs with high THM concentrations were able to comply
with the requirements of the Stage 1 D/DBPR and Stage 2 DBPR by adjusting their coagulation
methods and changing the point of chlorination, while also optimizing distribution operations to
minimize water age and optimizing booster chlorine use. Their greatest operation issue was a
need for increased attention to solids removal as a result of enhanced coagulation
Case Study #4 Switching Coagulants starting on page B-23 describes how a system
could simultaneously comply with the TOC removal requirements of the Stage 1 D/DBPR and
the turbidity removal requirements of the IESWTR by switching coagulants. The system found
that enhanced coagulation with ferric sulfate not only increased TOC removal significantly, but
also reduced turbidity levels in the finished water. The major problem experienced in
implementing the treatment modification was the control of manganese and corrosion in the
rapid mix chamber due to the addition of sulfuric acid.
Case Study #5 Enhanced Coagulation-Problems with Copper Pitting starting on page
B-29 describes a system that experienced pinhole leaks in their copper piping following
alterations to the coagulation process. The system implemented orthophosphate addition to
address the pinhole leaks, which also had an effect on finished water turbidity and iron release
from unlined cast iron mains.
Case Study #6 Enhanced Coagulation - Managing Radioactive Residuals starting
on page B-33 provides a discussion of a system's options for disposing of radioactive
residuals resulting from enhanced coagulation. As a result of enhanced coagulation,
radionuclides can become concentrated in residuals at levels that require special
consideration for regulatory approval of sludge disposal.
See Additional References
Readers can turn to Section 7.1.8 in Chapter 7 for technical references associated with
using enhanced coagulation.
Consider Additional Monitoring
The following are some suggestions for additional monitoring that may benefit water
systems using enhanced coagulation:
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S Routine turbidity or particle count monitoring of water leaving the sedimentation
basin to ensure that a consistently stable and dense floe is forming;
S Routine finished water pH and alkalinity monitoring to help ensure that corrosion
control is being implemented correctly; and
-S Periodic aluminum measurements in the finished water to watch for aluminum
carryover from the combination of alum floe and low pH.
The purpose of these monitoring suggestions is specifically to address and prevent potential
simultaneous compliance issues.
Consider Other Tools
In addition to water quality monitoring, there are additional tools available in Chapter 6
to help systems evaluate and improve their current water system in relation to the compliance
issues they may face when modifying their operation or treatment practices. Examples of tools
that can be used when enhanced coagulation is used for Stage 2 DBPR compliance include:
• The "Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual"
(USEPA 1999h) that provides recommended procedures for conducting jar testing to
determine the optimum coagulation conditions for achieving desirable total organic
carbon removal and coagulated/settled water turbidity;
• The AwwaRF report "Internal Corrosion of Water Distribution System" (AwwaRF
and DVGW-Technologiezentrum Wasser 1996), which provides bench-scale and
pilot testing protocols that can be used to evaluate changes in corrosion potential due
to changes in pH;
• EPA's Environmental Technology Verification Program collects performance data on
many environmental technologies, including enhanced coagulation. Reports for each
technology can be found on the website at:
http://www.epa.gov/etv/verifications/verification-index.html;
• The "Guidance Manual for Monitoring Distribution System Water Quality"
(Kirmeyer et al. 2002) which can be used to assist water utilities in implementing a
distribution system water quality data collection and analysis program;
• The second version of "Water Treatment Plant Model" (USEPA 200 Ih) developed by
EPA that assists utilities with implementing various treatment changes while
maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR;
and
• The Partnership for Safe Water publishes many materials useful in optimizing filter
performance. More information can be found on their website at:
http://www.awwa.org/science/partnership/.
Readers are encouraged to read through Chapter 6 before making any final compliance decisions.
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3.8 Enhanced Softening
Precipitative softening with lime addition is typically practiced with the objective of
removing hardness in the form of calcium and magnesium from water. Total hardness removal
goals vary among treatment plants. Lime softening processes are generally divided into three
distinct groups:
• Conventional lime softening to remove calcium carbonate where only lime is fed;
• Lime-soda softening to remove calcium carbonate and noncarbonate hardness by
feeding both lime and either soda ash or potassium carbonate; and
• Excess lime softening to remove both calcium and magnesium (and sometimes silica)
by adding an excess of lime.
All softening plants operate at higher pH levels than conventional coagulation plants.
Calcium carbonate begins to precipitate above pH of 9.5 and as the pH increases above 10,
magnesium hydroxide precipitation increases.
Generally, removal of TOC in
softening is enhanced by the
addition of a small amount of
coagulant.
Softening has some similarities to
coagulation with respect to the mechanisms
operating to remove particles and TOC, so that
when coupled with appropriate settling, DBF
precursors can be removed effectively by
softening. Generally, removal of TOC in
softening is enhanced by the addition of a small amount of coagulant. The regulatory
requirement for enhanced softening in the Stage 1 D/DBPR is based on the assumption that
raising the lime dose will foster the precipitation of CaCOs and the associated coprecipitation of
precursors. The resulting increase in pH causes increased precursor removal, presumably by
promoting stronger interactions between the precursors and calcium ions. In addition, the
increase in pH may be sufficient to precipitate magnesium hydroxide, which strongly adsorbs
precursors (Randtke 1999; Shorney and Randtke 1994).
When the pH of softening is changed significantly, differences in process chemistry
affect the nature of the solids that are formed with respect to settling and dewatering
characteristics. Enhanced softening criteria do not require plants to alter the softening process to
the extent that major changes in settling conditions and solids handling are generally required. A
plant is considered to be practicing enhanced softening if it meets the appropriate TOC removal
target in the 3x3 TOC removal matrix. Most softening plants have raw water alkalinity above
120 mg/L as CaCOs, so that they are classified in the right hand column of the matrix, but a few
fall into the classification for influent with alkalinity of 60 - 120 mg/L. Plants that cannot meet
the removal requirements in the 3x3 matrix may remain in compliance by removing a minimum
of 10 mg/L of magnesium as CaCO3. Alternatively, softening plants that reduce their finished
water alkalinity to 60 mg/L are in compliance with enhanced softening.
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3.8.1 Advantages of Enhanced Softening
The main advantages of enhanced softening are:
• Adequate removal of TOC
• Two stage plants may achieve additional Cryptosporidium removal credit
• Lower corrosion impacts
Adequate Removal of TOC
Softening plants typically do not have difficulty meeting the TOC removal requirements
of the 3x3 matrix in the Stage 1 D/DBPR. Information from a survey of softening plants (Clark
et al. 2000) indicated that operational data showed TOC being removed at least at the level
defined by the matrix, and this is substantiated by the data from the Information Collection Rule
(ICR). Since plants were not necessarily striving to meet the enhanced softening criteria during
the ICR sampling period, apparently the standard operating scheme for most softening plants
actually falls within the criteria of "enhanced softening" as defined by the rule (Clark et al.
2000).
The only instances reported by softeners which lead to difficulty in removing TOC occur
when raw water alkalinity drops significantly causing the calcium hardness:carbonate alkalinity
ratio to be elevated. This situation can arise when surface water is diluted by major rain events
or when a blend of ground and surface water is altered in proportions. In these cases, some
addition of carbonate alkalinity in the form of soda ash or potassium carbonate may be warranted
to facilitate the softening reactions and the coprecipitation of organic material. Softening utilities
are expected to be able to meet the requirements of the Stage 2 DBPR as effectively, or more so,
as conventional coagulation plants (USEPAN.d.e).
Two Stage Plants May Achieve Additional Cryptosporidium Removal Credit
Plants that include a two-stage lime softening process are eligible for an additional 0.5-
log Cryptosporidium removal credit toward compliance under LT2ESWTR if chemical addition
and hardness precipitation occur in two separate and sequential softening stages prior to
filtration. The two-stage process must consist of a second clarification step between the primary
clarifier and filters. Both clarifiers must treat all of the plant flow. Refer to the LT2ESWTR
Toolbox Guidance Manual (USEPAN.d.e) for a description of the requirements for receiving
this credit.
Lower Corrosion Impacts
Softening systems have an advantage with respect to managing corrosion for two reasons.
Since the softening process takes place at a pH above 10, systems generally add carbon dioxide
to reduce pH and stabilize the water prior to distribution. Selection of an appropriate finished
water pH goal takes into consideration the optimum pH for corrosion control. At the same time,
softening systems generally produce water that tends to develop scale in the distribution system.
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If the scale formation is not managed appropriately, it can be a liability with respect to flow
restriction, but from a corrosion control standpoint, scale formation is a distinct benefit.
As noted in EPA's "Enhanced Coagulation and Enhanced Precipitative Softening
Guidance Manual" (USEPA 1999h), the information in Exhibit 3.6 is intended only to
characterize existing and future corrosion control strategies. The figure can be used proactively
to anticipate problems that may develop if enhanced softening is used.
Exhibit 3.6 Effect of the Change of Water Quality Parameters Due to Enhanced
Softening on Corrosion of Piping System Materials
Parameter
TOC
Alkalinity
Ca Hardness
PH
Potential
Change
Resulting From
Enhanced
Softening
T
T
^
T
A
1 applies to copper
2 applies to copper by-products
^
Impact on Corrosion of Material
Pb
^
^
^
T = decrease
Cu
^
1
T2
*•
^
Fe
T
A
^
A = increase
Pb from
Brass
T
^
^
Concrete
A
A
^
^ = same (no change)
Source: USEPA's Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual (USEPA 1999h)
3.8.2 Potential Operational and Simultaneous Compliance Issues Associated
with Enhanced Softening
Potential issues associated with enhanced softening include:
• Options for disinfection are limited
• Higher TTHM formation at high pH
• Can cause scaling
• pH adjustment required for distribution and for disinfection effectiveness
• Increased sludge volume and changes in sludge characteristics
This section briefly describes these issues and provides suggestions for minimizing their impacts.
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Disinfection considerations
One of the most complex issues facing softening plants with respect to regulatory
compliance is selection and implementation of disinfection processes. Disinfection with
chlorine, chloramines, chlorine dioxide, and ozone requires specific consideration of issues that
arise in high pH waters.
The state must evaluate
disinfection credit using
chlorine or chloramines
through the softening
portion of the treatment
process on a case-by-case
basis.
Based on data from an AWWA survey of
softening plants completed in 1997 to inform the
regulatory development process, more than one third
of softening plants predisinfect with chlorine, ozone,
or a combination of chlorine/chloramines and they
take CT credit for some or all predisinfection contact
time. In addition, the survey indicated that the
finished water pH in softening plants ranges from 7.5
to 10, with approximately half reporting average
finished water pH greater than 9. CT values for inactivation of Giardia by free chlorine and
chloramines are not identified for pH levels greater than 9 in the SWTR Guidance (USEPA
1991). Thus, the state must evaluate disinfection credit using chlorine or chloramines through
the softening portion of the treatment process on a case-by-case basis to ensure that the total
treatment processes achieve at least 3-log treatment of Giardia and 4-1 og treatment of viruses.
Some softening plants have resolved this problem by providing appropriate contact time after
softening and pH reduction to meet required CT values with their selected disinfectant.
Use of chlorine dioxide in softening plants is governed by the regulated levels for
chlorine dioxide and chlorite. Chlorine dioxide reacts with many organic and inorganic
constituents in water. It disinfects by oxidation, but does not chlorinate. Chlorine dioxide
functions as a highly selective oxidant due to its unique, one-electron transfer mechanism where
it is reduced to chlorite. The reactions produce chlorite and chlorate as endpoints. In drinking
water, chlorite (CICV) is the predominant reaction endpoint, with approximately 50 to 70 percent
of the chlorine dioxide converted to chlorite and 30 percent to chlorate (CICV) and chloride (Cl")
(USEPA 1999h). The balance between these two species varies frequently and is affected by the
exposure to bright sunlight, aeration, and recarbonation, among other factors (Gates 1997). The
disproportionation of C1O2 is accelerated by increased pH, which means that the addition of lime
soon after the addition of C1O2 may result in minimal disinfection time and development of both
chlorite and chlorate (Hoehn 1993). There may be situations in which chlorine dioxide can be
used as a preoxidant in softening plants, but they would be governed by the contact time
available prior to the addition of lime and initiation of the softening process.
Ozone use at high pH (above pH 7) will form significant bromate when bromide is
present in the water. Ozonation at lower pH can control the formation of bromate, but will
increase the formation of brominated organic byproducts produced from the interaction between
hypobromous acid and NOM, producing an overall increase in TTHM by weight (Reckhow
1999). In softening plants, the use of ozone generally requires reduction of pH from the
softening pH (between 10 and 11) to a pH between 6 and 7. To obtain such a shift in pH,
significant amounts of acid are often consumed. Thus, unless a unique water quality concern
requires use of ozone, other disinfection options should be considered.
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Higher THM Formation
In addition to increasing with chlorine dose and presence of DBF precursors, THM
formation has been shown to be higher with increasing chlorination pH. Some HAAs, in
contrast appear to have lower formation at higher pH (Singer 1999). A number of softening
plants have constructed a large chlorine contact chamber/clearwell to provide disinfection
contact time after the pH of the water is lowered from the softening pH to a pH that minimizes
DBF production.
Many raw water sources that are treated by softening contain significant levels of
bromide. As plants practice enhanced softening to remove precursors, the ratio of the amount of
bromide in the water to the amount of TOC goes up because bromide is not removed by
softening. Research has shown that as the ratio of bromide to TOC increases the percentage of
brominated DBFs increases. Thus, when bromide-containing enhanced softened water is
disinfected with chlorine, formation of brominated THMs increases, resulting in a higher total
weight of THMs formed. Thus, softening plants may be forced into a balancing of TOC removal
with DBF formation to optimize the finished water DBF formation based on speciation of the
THMs and total weight of TTHM.
Recommendations for Addressing this Issue
If softening plants have problems complying with the proposed Stage 2 DBPR TTHM
MCLs, three possible alternatives should be considered.
• Systems may be able to reduce finished water pH somewhat to reduce the TTHM
formation potential in the system. Changes in system pH should be cautiously
undertaken to ensure that the existing system scale is not altered significantly,
softened, or stripped from pipes, thereby causing major operational problems;
• Systems may be able to utilize alternative disinfectants, including chloramines,
chlorine dioxide, or ozone. Chloramines are best suited for use as a distribution
system residual although some softening plants operate with a chloramine residual
carried through the softening process. Chlorine dioxide and ozone disinfection
should be evaluated with care in both quantity and placement to ensure that neither
chlorate nor bromate MCLs are violated. Use of UV for disinfection may reduce the
level of chlorine or chloramine residual required for residual disinfection in the
distribution system; and
• Softening plants may also evaluate the possible conversion from conventional
softening to membrane softening. The use of microfiltration followed by
nanofiltration can remove TOC as well as provide softened water, thereby reducing
the DBF formation potential. Cost may be a factor that prohibits a system from
making this change. In addition, membrane conversion can necessitate the need to
consider other simultaneous compliance issues such as ensuring that distribution
system chemical equilibrium is not altered in a way that will cause either corrosion or
scale sloughing.
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Scaling
Depending on the raw water quality and the physical configuration of the treatment
processes in a softening plant, the addition of extra lime to provide enhanced softening
conditions can lead to increased scaling conditions in both the treatment plant and the
distribution system piping. In general, if the Langelier Saturation Index (LSI) is positive, the
water is oversaturated with CaCOs and has the potential to precipitate and form scale.
pHAdjustment Requiredfor Distribution and for Disinfection Effectiveness
Most softening plants adjust pH to meet finished water pH goals, to meet pH
requirements for disinfection effectiveness after the completion of the softening process, and to
satisfy distribution system chemical equilibrium. As the pH of softening is increased in an effort
to remove more TOC, the quantity of chemical required for pH adjustment increases.
Historically, the finished water pH in softening plants has ranged between 7.5 and 10.
Increased Sludge Volume and Changes in Sludge Characteristics
Significant increases in lime doses will result in increased lime sludge production.
Residuals production may also increase when lime addition results in a pH greater than 10.25 in
plants with significant magnesium present that have not historically softened at pH greater than
10. At that pH, the magnesium hydroxide is precipitated along with calcium carbonate. If
significant noncarbonate hardness exists, then addition of soda ash may be necessary, resulting in
increased residuals production and higher sodium levels in the finished water. In addition, the
handling and dewatering characteristics may be significantly altered (Randtke et al. 1999).
In the softening process, calcium carbonate forms a dense crystal that is negatively
charged, while magnesium hydroxide forms large, light floe that has a high surface area and
positive surface charge. This difference in particle characteristics is what makes magnesium
hydroxide a better adsorbent for dissolved precursors; however magnesium hydroxide solids
have settling and dewatering characteristics that are quite different from calcium carbonate
solids. In fact, softening plants that are designed to settle calcium carbonate may very well have
inadequate settling time to settle magnesium hydroxide. If the previous softening pH was less
than 10.25 and the water has significant magnesium, then enhanced softening in which the pH is
increased to greater than 10.25 can cause formation of magnesium hydroxide, which may not be
effectively removed in the settling process, or may change the characteristics of the process
solids.
3.8.3 Recommendations for Gathering More Information
See Additional References
Readers can turn to Section 7.1.8 of Chapter 7 for technical references associated with
enhanced softening
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Improving and Optimizing Current Operations
Consider Additional Monitoring
The following are some suggestions for additional monitoring that may benefit softening
systems. The purpose of these monitoring suggestions is specifically to address and prevent
potential simultaneous compliance issues.
•S Routine LSI measurements, or another comparable calcium carbonate saturation
index, of water entering the distribution system to monitor the potential for excess
scale formation. Weekly measurements may be sufficient when raw water quality is
relatively consistent. More frequent checks may be useful under changing raw water
conditions.
Consider Other Tools
In addition to water quality monitoring, there are additional tools available in Chapter 6
to help systems evaluate and improve their current water system in relation to the compliance
issues they may face when modifying their operation or treatment practices. Examples of tools
that can be used when enhanced softening is used for Stage 2 DBPR compliance include:
• The "Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual"
(USEPA 1999h) that provides recommended procedures for conducting jar testing to
determine the optimum coagulation and softening conditions for achieving desirable
total organic carbon removal and coagulated/settled water turbidity;
• The AwwaRF report "Internal Corrosion of Water Distribution System" (AwwaRF
and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot
testing protocols that can be used to evaluate changes in corrosion potential due to
changes in pH;
• The "Guidance Manual for Monitoring Distribution System Water Quality"
(Kirmeyer et al. 2002) which can be used to assist water utilities in implementing a
distribution system water quality data collection and analysis program; and
• The second version of "Water Treatment Plant Model" (USEPA 200 Ih) developed by
EPA that assists utilities with implementing various treatment changes while
maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR.
Readers are encouraged to read through Chapter 6 before making any final compliance decisions.
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Installing New Total Organic Carbon
or Microbial Removal Technologies
After improving and optimizing current operations, some water systems will still need to
install a new type of treatment in order to comply with the Stage 2 DBPR and/or the
LT2ESWTR. This chapter describes treatment technologies that can be installed to remove DBF
precursors and microbial pathogens. Advantages of using each treatment are described, along
with summaries of operational and simultaneous compliance issues associated with the
treatment. General recommendations for
addressing those issues are provided,
along with recommendations for gathering
more information. While most of the
issues presented in the following sections
address simultaneous compliance
concerns, some additional operational and
aesthetic issues are discussed.
TREATMENTS COVERED
Granular Activated Carbon
Microfiltration/Ultrafiltration
Nanofiltration
Other Microbial Removal Technologies
4.1 Granular Activated Carbon
The main benefit of granular activated carbon (GAC) is that it is effective in adsorbing
and removing organic compounds from water. Removing organic matter lowers DBFs, taste and
odor complaints, and microbial activity in the distribution system. Additionally, if GAC is used
in series with a conventional filter, as illustrated below, systems may be able to receive
additional Cryptosporidium removal credit under the LT2ESWTR. The main drawbacks to
using GAC are the possibility of release of bacteria or carbon fines into the system, the
possibility of chromatographic peaking, and its reaction with disinfectants. These issues are
discussed in more detail in Section 4.1.2.
Caustic
Rapid Mix Flocculation/ Filtration Interstage GAC Filter
Sedimentation Pumping
Storage
GAC can be used as an additional layer on top of an existing filter (GAC cap), or it can
be placed in a separate contactor. Design will vary depending on whether it is used as a separate
adsorber or if it is added as a filter cap. Its efficiency is determined by the contact time and the
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
relative adsorption strength of the compounds that are to be removed. Some physical removal by
filtration will occur in GAC beds as well.
4.1.1 Advantages of GAC
Advantages of GAC include:
• Removes DBF precursors
• Can remove taste and odor compounds
• If used as a secondary filter, the system may be able to receive a 0.5-log
Cryptosporidium removal credit
• Can be used as a biologically active filter after ozone to remove assimilable
organic carbon (AOC)
DBF Precursor Removal
DBF precursor removal before the addition of a disinfectant can significantly lower DBF
production and ease compliance with the Stage 2 DBPR. GAC 10, a GAC contactor with a 10
minute empty bed contact time (EBCT), is considered a best available technology (BAT) for the
Stage 1 D/DBPR. GAC 10 in combination with enhanced coagulation or enhanced softening or
GAC20 are considered BATs for the Stage 2 DBPR. GAC has been found to reduce total organic
carbon (TOC) by 30 to 90 percent depending on the contact time, the nature of the organic
matter, and other parameters (USEPA 2003d and references therein). Generally, AOC is
removed relatively quickly while other organic fractions take longer to remove.
Taste and Odor Removal
Because many taste and odor compounds are organic, the ability of GAC to adsorb
organics also makes it a useful treatment technique in this respect. For example, GAC has been
found to remove 30 to 40 percent of geosmin from drinking water (Youngsug et al. 1997). The
removal efficiency was increased to 80 percent or more with the addition of ozone or peroxone.
Similar reductions can be achieved for 2-methylisoborneol (MIB).
Cryptosporidium Removal
Systems can receive a 0.5-log
Cryptosporidium removal credit for having
a second set of filters in series in a
conventional treatment plant. Both a GAC
contactor and a conventional dual media
filter with a GAC cap are eligible for this
credit. In both cases the Cryptosporidium is
removed through physical filtration onto the
filter media. The filter must treat the entire
Using GAC in a second filter can:
• lower DBF precursors and other organics
• help meet the Stage 2 DBPR requirements
• achieve Cryptosporidium removal credit for
the LT2ESWTR
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
flow of the plant to obtain the credit. Refer to the LT2ESWTR Toolbox Guidance Manual
(USEPA N.d.e) for a description of rule requirements for receiving credit.
Removes AOC After Ozone
Ozonation often results in organic matter becoming AOC, which serves as a food source
for microbes. This can cause difficulties with compliance with the Total Coliform Rule (TCR)
and can lead to nitrification problems. GAC, acting as an adsorbent, can remove some AOC
before it enters the distribution system.
Additionally, systems can take advantage of the high surface area per mass ratio of GAC
and the fact that it adsorbs organics to operate the GAC filter in biologically active mode. By
not having a disinfectant residual in the water passing through the filter and allowing biological
growth, the system can achieve high removals of AOC. Using biologically active GAC filters
after ozonation can reduce biological growth in the distribution system and lower DBFs. See
Section 5.2 for further details on the use of biological filtration with ozone.
4.1.2 Potential Operational and Simultaneous Compliance Issues Associated
with Using GAC
Potential issues associated with GAC use include:
• Can limit the ability to prechlorinate;
• Previously adsorbed compounds can be released;
• Bacteria can be released;
• Carbon fines released from GAC filters can foul downstream processes;
• Chlorate can be formed when GAC comes in contact with chlorine dioxide; and
• Ammonia added before a GAC filter has been found to increase nitrification in
the distribution system.
This section briefly describes each of these issues and provides some suggestions for
addressing them.
Limits Ability to Pre-chlorinate
Most disinfectants react quickly when they come into contact with GAC. This leads to a
rapid loss of disinfectant residual, and in the case of chlorine, can lead to a faster depletion of the
GAC.
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
Recommendations for Addressing this Issue
Systems should not use GAC filters at the same time as achieving CT for purposes of
meeting disinfection requirements. Disinfectants should be added after the GAC filter. If the
disinfectant addition points are moved, an evaluation of the CT throughout the plant must be
made and any effects of moving the disinfection point, such as changes in coagulation and
precipitation, pre-oxidation of contaminants, and growth of algae should be evaluated. If pre-
oxidation is needed in treatment before GAC, alternative oxidants (e.g., potassium
permanganate) or lower chlorine doses should be used so as not to carry a residual onto the
GAC.
Release of Adsorbed Compounds
Organic materials adsorbed onto GAC will generally remain on the GAC until it is
regenerated. But if a stronger adsorbing compound passes through the GAC when the GAC is
relatively saturated, and the GAC does not have a significant number of free adsorption sites,
weaker binding compounds can be expelled. It is possible for the concentration of these expelled
compounds to be higher than the original concentration. This phenomenon is referred to as
chromatographic peaking. Strongly adsorbing compounds that can have this effect include
hydroxide used to adjust pH, or chloride as a byproduct of chlorination.
Recommendations for Addressing this Issue
To avoid chromatographic peaking and the desorption of contaminants from the GAC,
pH adjustment should be made after the GAC filter. Chlorine should also generally be added
after the GAC filter, both to avoid chromatographic peaking and to lower DBF formation. Any
other sudden changes in water chemistry entering the GAC contactor should be avoided as well.
If sudden swings in water chemistry are unavoidable, then GAC regeneration frequency should
be increased and the filter effluent should be monitored carefully to prevent breakthrough of any
contaminants.
Release of Bacteria
Studies have found that the average number of bacteria in the effluent of GAC filters can
be significantly higher than influent levels (Parson et al. 1980; Klotz et al. 1976), indicating that
heterotrophic bacteria growth may occur within the filters. For systems using GAC filtration that
have inadequate post-GAC disinfection, bacteria may enter the distributon system. The primary
concern with this potential bacteria release is the possible presence of pathogenic
microorganisms. Other concerns include the possible presence of ammonia-oxidizing bacteria
that could trigger a nitrification event if ammonia is present, and bacteria growth in distribution
system biofilms.
Recommendations for Addressing this Issue
The amount of bacteria in the effluent of GAC systems can often be reduced by proper
backwashing and GAC regeneration frequencies. However, some bacteria are still likely to be
shed from GAC filters. Introducing a disinfectant residual in the filter itself is not recommended
because most disinfectants react with GAC, spending the GAC and not penetrating the full depth
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
of the bed. The best strategy to deal with bacteria shed from GAC filters is to add a disinfectant
after the GAC filter.
Release of Carbon Fines
Small particles of carbon are usually present in GAC filters when they are first installed.
These carbon fines appear gray or black and can cloud the water. If carbon fines from GAC
filters are released into the product water, they can interfere with downstream treatment
processes, particularly fouling of membrane filters and absorbing ultraviolet (UV) light in UV
disinfection units, and cause poorer performance of these subsequent treatment steps.
Recommendations for Addressing this Issue
GAC filters should be placed after membrane or UV disinfection processes to avoid
problems associated with the release of carbon fines. If this is not possible, proper backwashing
procedures, good maintenance of the filter underdrains, and more frequent cleaning of the UV
reactor or membrane unit can help to minimize the problem.
Formation of Chlorate
Chlorine dioxide, in addition to losing its residual, will form chlorate when it comes into
contact with GAC. Chlorate can further react to form chlorite, a DBF regulated by the Stage 1
D/DBPR.
Recommendations for Addressing this Issue
Chlorine dioxide should be added after the GAC filters to avoid the formation of chlorate.
If chlorine dioxide is used for pre-oxidation, it should be added far enough ahead of the GAC
filter that no residual enters the contactor. If the treatment sequence first has conventional
filtration and then the GAC filter, adding the chlorine dioxide prior to the first set of filters will
usually solve the problem.
Nitrification with Chloramines
Systems that add ammonia prior to a GAC contactor have been found to have more
frequent incidents of nitrification in the distribution system (Krasner et al. 2003). This may be
caused by the ammonia stimulating growth of nitrifying bacteria on the GAC media and seeding
the distribution system with these bacteria, though the research has not been conclusive.
Recommendations for Addressing this Issue
To reduce the potential for nitrification, systems using ammonia to form chloramines or
to raise pH should add the ammonia after the GAC filters.
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
4.1.3 Recommendations for Gathering More Information
Read the Case Study
For more information on simultaneous compliance issues associated with GAC and how
to address them, see Case Study #7- Granular Activated Carbon for TOC removal starting on
page B-39 of Appendix B. This case study describes how a utility used GAC to address high
levels of atrazine in its source water and high TTHM levels in its finished water. The system
was able to reduce their atrazine levels 30 to 60 percent and their UV254 levels 20 percent six
months after installing the GAC cap. The greatest operational issue faced by the system was a
build up of inorganic precipitates on the GAC filter, and occasional taste and odor episodes.
See Additional References
Readers can turn to Chapter 7 for more references on this topic. Section 7.1.1 includes
general references on water treatment, Section 7.1.2 contains references on controlling DBF
formation, and section 7.1.9 contains references on GAC use.
Consider Additional Monitoring
The following are some suggestions for additional monitoring that may benefit water
systems implementing GAC. Note that the purpose of these monitoring suggestions is
specifically to address and prevent potential simultaneous compliance issues. Water system
managers should discuss process control monitoring with the GAC manufacturer or their
engineer.
•^ Periodic monitoring of volatile organic chemicals (VOCs) and synthetic organic
chemicals (SOCs), as appropriate, in water leaving the GAC unit to detect
breakthrough and desorption of contaminants;
•S Turbidity or particle count measurements of the GAC effluent, especially when new
or re-activated carbon is first being used; and
•S Heterotrophic plant counts (HPC) in water leaving the GAC units to watch for an
increase in bacteria numbers.
Consider Other Tools
In addition to water quality monitoring, there are additional tools described in Chapter 6
to help systems evaluate and improve their current water system in relation to the compliance
issues they may face when modifying their treatment practices. Examples of tools that can be
used when GAC is used for Stage 2 DBPR compliance include:
• The AwwaRF report "Prediction of GAC Performance Using Rapid-Small Scale
Column Tests" (Crittenden 1989) that describes the use of RSSCT techniques to
predict full-scale GAC's useful lifetime when it is used to remove dissolved organic
matter from a drinking water source. This report also demonstrates how to use pilot-
scale testing data to further refine the RSSCT prediction;
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
• The "Handbook of Public Water Systems" (HDR Engineering, Inc. 2001) which
provides detailed engineering design aspects of various drinking water treatment
processes including granular activated carbon;
• EPA's ICR Treatment Study Database contains the results of 63 pilot studies of GAC
plants. It can be found on the web at:
www.epa.gov/safewater/data/icrtreatmentstudies.html:
• The second version of "Water Treatment Plant Model" (USEPA 200 li) developed by
EPA in 2001 that assists utilities with implementing various treatment changes, while
maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR;
and
• Various cost estimation models that can be used to estimate the cost of constructing
and operating a new GAC facility (See Section 6.3.7).
Readers are encouraged to read through Chapter 6 before making any final compliance decisions.
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
4.2 Microfiltration/Ultrafiltration
Microfiltration/Ultrafiltration (MF/UF) is a low-
pressure membrane technology. The membranes remove
particulate matter larger than the membrane pore size. MF
membranes generally operate at slightly lower pressure and
have larger pore sizes than UF membranes. In some cases,
MF/UF membranes will be used together, with the MF
membranes acting as a pre-filter for the UF membranes.
MF/UF units are often supplied on skid mounted assemblies
that can easily be installed and have high degrees of automation.
An advantage of MF/UF is that it can achieve
high removal rates of bacteria, G/arcf/aand
Cryptosporidium. This allows a system to
lower its disinfectant dose and possibly reduce
its finished water DBF concentrations.
4.2.1 Advantages of MF/UF
Advantages of MF/UF include:
• Removes bacteria and
protozoa
• Can lower DBFs by allowing
lower disinfectant doses
• Can remove particulate arsenic
Bacteria and Protozoa Removal
Membrane processes remove all particles larger than the pore size of the membrane,
provided the membrane integrity is not compromised. Bacteria, Cryptosporidium oocysts, and
Giardia cysts can all be reliably removed by MF/UF. Although MF membranes do not generally
remove viruses, some UF membranes can remove viruses. MF/UF units that are challenge-tested
before installation and undergo membrane integrity tests qualify for additional Cryptosporidium
removal credit as determined based on testing results. See the LT2ESWTR Toolbox Guidance
Manual (USEPA N.d.e) for more information. Systems should also consult with their state to
determine applicable credits and requirements.
If surface water systems use MF/UF instead of chemical disinfection to get
inactivation/removal credit, they must add a disinfectant such as chlorine or chloramines to
maintain a disinfectant residual in the distribution system.
DBF Reduction
Because MF/UF can achieve high levels of microbial removal, systems installing MF/UF
can lower their disinfectant dose and still achieve the same level of microbial protection. The
lowered disinfectant dose may result in lower DBFs and aid in meeting Stage 2 DBPR
requirements.
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
Arsenic Removal
MF/UF membranes do not have a small enough molecular cut-off weight to remove
dissolved or colloidal arsenic. They can, however, remove particulate arsenic. The removal will
depend on the size distribution of particles the arsenic is bound to and the pore size of the
membrane. A coagulation step prior to the membranes will help to improve arsenic removal.
Electrostatic repulsion can also help increase arsenic removal in MF/UF systems. The increase
in removal will depend on the charge of the membrane, the oxidation state of the arsenic, and the
pH of the water. Removal rates have been shown to vary between 5 and 70 percent (Amy, et al.
2000).
4.2.2 Potential Operational and Simultaneous Compliance Issues Associated
with MF/UF
Potential issues associated with MF/UF use include:
• Can be fouled by organics and minerals
• Increased loss of process water
• Additional training required
This section provides brief descriptions of these issues and suggestions for minimizing
their impacts.
Membrane Fouling
Membranes can be fouled by organic matter, iron, manganese, and carbonate deposits.
Sources of these fouling compounds include source water and treatment chemicals. Ground
water systems that do not treat their water before it passes through the MF/UF unit may have
particular problems with iron, manganese, and other minerals. This is especially true if the
ground water is anoxic and is exposed to the atmosphere during pumping or an aeration process,
resulting in dissolved minerals settling out.
Recommendations for Addressing this Issue
Systems with high TOC can
reduce fouling by placing the MF/UF
after existing sedimentation and/or
filtration processes. If TOC is high
even after filtration, TOC can be
lowered by adding other pretreatment
techniques. Pretreatment to lower
TOC levels includes: pre-
sedimentation, enhanced coagulation,
and, less often, GAC filtration. TOC removal can often be accomplished by good coagulation
before the membranes. If iron-based coagulants are used, jar testing should be carried out to
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For the Long Term 2 and Stage 2 DBF Rules
If TOC is high after filtration, it can be lowered
through other pretreatment techniques, including:
• Pre-sedimentation
• Enhanced coagulation
• GAC filtration (less often)
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
ensure optimal dosing and settling, because iron-based coagulants can foul some membranes.
GAC filtration removes much of the organic matter, although not all organic compounds are
adsorbed easily. A cartridge filter may need to be installed before the MF/UF unit, however, to
prevent carbon fines from entering the membrane unit.
Systems that aerate their ground water to oxidize iron, manganese or other compounds
should remove any precipitated minerals before the water reaches the MF/UF unit to prevent
fouling. The manufacturer of the MF/UF unit and other utilities with experience using the same
units should be consulted before a system makes any changes to the chemistry of the treated
water, since many treatment chemicals can also foul membranes.
Regardless of the pretreatment involved and the quality of the water, membranes will
eventually foul and will need to be cleaned. Cleaning the membranes will improve performance
and prolong membrane life. The appropriate length between cleanings can be determined by
monitoring the long-term decrease in productivity and backwash efficiency.
Loss of Process Water
Membrane processes produce reject streams as well as backwash water. Therefore, the
amount of wastewater that has to be handled can be higher than that produced during
conventional filtration. Although improvements have been made in efficiency, some water
systems lose as much as 15 percent of the process water as a waste stream. Other membrane
projects have been bid with approximately 92 percent recovery in summer and 90 percent
recovery in winter (Sarah Clark, personal communication). In a recent survey of MF/UF
systems, however, the median value for feed water recovery was 95 percent (Adham et al. 2005).
Recommendations for Addressing this Issue
To handle the higher quantities of process water produced by MF/UF units, systems may
need to increase the capacity of their wastewater storage and residuals processing facilities. This
is especially true of systems that recycle their reject water.
To minimize the lost water, systems may also be able to recycle some of the reject stream
if the membranes are added onto a conventional treatment train. In this case, the recycle must be
sent to the head of the plant according to the Filter Backwash Recycling Rule (FBRR), unless the
State approves an alternate location. The effect of additional particle loading should be taken
into account when determining coagulant dosing and filter loading rates.
Additional Training Required
MF/UF membranes are significantly different to operate than other water treatment units.
The control parameters are different; the State will determine the parameters that the system
must monitor to demonstrate regulatory compliance.
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
Recommendations for Addressing this Issue
Systems should consult with their state to determine what parameters will need to be
monitored for approval and regulatory compliance. Systems should also work with the state and
the vendor to provide adequate training for operators.
4.2.3 Recommendations for Gathering More Information
See Additional References
Readers can turn to chapter 7 for further references on this topic. Section 7.1.1 contains
general references on water treatment, and section 7.1.10 contains references on membranes,
including MF/UF.
Consider Additional Monitoring
The following are some suggestions for additional monitoring that may benefit water
systems implementing MF/UF. Note that the purpose of these monitoring suggestions is
specifically to address and prevent potential simultaneous compliance issues. Water system
managers should discuss process control monitoring with the MF/UF manufacturer and other
experienced utilities.
•^ Periodic monitoring of iron, manganese, and other minerals in the water entering the
MF/UF unit to detect an increase in minerals that may need to be addressed by pre-
treatment;
S Particle counting to indirectly monitor membrane integrity and determine if a direct
integrity test should be conducted;
•S Total organic carbon (TOC) in the membrane unit's influent and effluent to track
removal performance;
•S Heterotrophic plate counts (UPC) in the membrane unit's effluent if membrane
integrity is lost; and
S Membrane autopsies on any failed membranes to determine the cause of failure and
determine possible corrective actions.
Consider Other Tools
In addition to water quality monitoring, there are additional tools available in Chapter 6
to help systems evaluate and improve their current water system in relation to the compliance
issues they may face when modifying their treatment operations. Examples of tools that can be
used when MF/UF membranes are used for LT2ESWTR and Stage 2 DBPR compliance include:
• The "Membrane Filtration Guidance Manual" (USEPA 2005b) provides general
recommendations for membrane pilot testing;
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
• The AwwaRF report "Integrated Membrane Systems" (Schippers et al. 2004) that
provides guidance on the selection, design, and operating an integrated membrane
system that can function as a synergistic system for removing microbiological
contaminants and DBF precursors;
• The AwwaRF report "Integrating Membrane Treatment in Large Water Utilities"
(Brown and Hugaboom 2004) that provides guidance to issues related to the
integration of low pressure membranes into larger water treatment facilities, including
membrane layout, piping, cost comparison, and operations and maintenance;
• EPA's Environmental Technology Verification Program collects performance data on
many environmental technologies, including MF/UF. Reports for each technology
can be found on the website at: http://www.epa.gov/etv/verifications/verification-
index.html;
• The second version of "Water Treatment Plant Model" (USEPA 200 li) developed by
EPA in 2001 that assists utilities with implementing various treatment changes while
maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR;
and
• Various cost estimation models, such as WTCost©, 2003, that can be used to estimate
the cost of implementing a new membrane facility (see Section 6.3.7).
Readers are encouraged to read through Chapter 6 before making any final compliance decisions.
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
4.3 Nanofiltration
Nanofiltration is a membrane process that
physically removes contaminants from water that are larger
than the pore size of the membranes. Nanofiltration uses
8KB
pore sizes and operating pressures that fall between those
of UF and reverse osmosis.
Nanofiltration's main advantage over MF/UF is that
it can remove virtually all paniculate matter as well as
larger dissolved compounds, including dissolved organic
matter. In addition to meeting all removal requirements for pathogens, it leads to lower DBFs by
removing DBF precursors. Its main disadvantages are that it can be fouled by organics or
precipitated minerals, it can increase corrosiveness of the water, it has a large reject stream, and
it requires additional training.
4.3.1 Advantages of Nanofiltration
Some advantages of nanofiltration include:
Significant removal of bacteria,
protozoa, and viruses
Can remove organics that act as
DBF precursors
Removes arsenic
Nanofiltration's main advantage is that it
can remove virtually all paniculate matter
as well as larger dissolved compounds,
including some dissolved organic matter
Significant Removal of Bacteria, Protozoa, and Viruses
Nanofiltration has small pore sizes that exclude essentially all paniculate matter, as long
as the membrane is intact. Therefore, nanofiltration units that are capable of being integrity
tested may receive credit for Cryptosporidium removal under LT2ESWTR.
Removes DBF Precursors
Nanofiltration can remove dissolved organic compounds that serve as DBF precursors.
When little or no bromide ion was present in the source water, nanofiltration membranes with
molecular weight cutoffs (MWCOs) of 400 to 800 daltons were shown to effectively control
DBF formation (Laine et al. 1993). Nanofiltration with the same pore size produced higher
bromoform concentrations when bromide was present, although total THMs decreased.
Membranes with smaller pore sizes controlled bromoform formation better but required
pretreatment to avoid membrane fouling.
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DBF formation may be lowered even further if the state allows the system to reduce its
disinfectant dose and the amount of primary disinfection because of the high microbial removal
rate of the nanofiltration units. When this is the case, nanofiltration can accomplish both high
pathogen removal and low DBF formation.
Removes Arsenic
Nanofiltration membranes can remove both dissolved and particulate arsenic through size
exclusion and electrostatic repulsion. Removal rates will depend on the surface charge of the
membrane, speciation of the arsenic, dissolved organic concentration, and pH. Oxidized arsenic
(V) is removed much more efficiently than reduced arsenic (III). Single element tests have
found rejection rates for arsenic (V) between 80 and 95 percent (Amy et al. 2000). Other tests on
pilot scale membranes have found the removal can decrease to between 65 and 75 percent over
time (Malcolm Pirnie 1992, Chang et al. 1994).
4.3.2 Potential Operational and Simultaneous Compliance Issues Associated
with Nanofiltration
Potential issues associated with nanofiltration include:
• Can be fouled by organics and precipitated minerals
• Can increase corrosiveness of water
• Issues with reject stream
• Additional training required
This section briefly describes these issues and provides suggestions for addressing their
impacts.
Membrane Fouling
Organics and precipitating minerals can foul nanofiltration membranes and cause them to
operate inefficiently, shortening their useful life. Fouling also increases operating pressures and
causes more frequent backwashing, which raises operating expenses. Fouling agents can come
from the source water or be introduced as part of the treatment process. Ground waters that are
not filtered before the water passes through the membranes may have more difficulties with
fouling due to high mineral concentrations.
Recommendations for Addressing this Issue
If nanofiltration membranes are being used in conjunction with a conventional filtration
plant, the membranes should be placed after the filters to allow for the maximum removal of
fouling compounds before water passes through the membranes. Treatment processes that can
change the chemistry of the water should be located downstream of the nanofiltration unit if
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
possible. These include pH adjustment and disinfectants. Systems should bear in mind,
however, that nanofiltration generally works better at acid pH.
If the treatment train in place is not sufficient to reduce fouling compounds, some sort of
pretreatment will be required. The simplest pretreatment is often adding a cartridge filter before
the membranes. If the water being treated is anoxic ground water, aeration may be considered to
oxidize and precipitate any minerals before the cartridge filter. Other options for pretreatment
include enhanced coagulation and pre-sedimentation. If enhanced coagulation is used, jar testing
should be conducted to optimize the dose to ensure that unflocculated coagulant does not enter
the membrane unit.
Regardless of the pretreatment involved and the quality of the water, membranes will
eventually foul. Cleaning the
membranes is necessary for
improving performance and
prolonging membrane life. The
appropriate length between
cleanings can be determined by
monitoring the long-term decrease
in productivity and back wash
efficiency.
If coagulants or disinfectants are added prior
to membranes, the system should consult the
membrane manufacturer and other
experienced utilities to determine if the
chemicals will cause fouling or otherwise
damage the membranes.
Increase Corrosiveness
Nanofiltration can soften water by removing minerals such as calcium and magnesium. It
can also result in a lowering of the pH of the water. The less alkaline, lower pH water will be
more corrosive to distribution system piping and other process equipment, while not providing a
passivating layer as harder water can. The lower pH can also shift the carbonate equilibrium to
produce carbon dioxide. In groundwaters, hydrogen sulfide can also pass through the
membranes. All these factors combine to increase the corrosiveness of the water.
Increased corrosiveness can cause problems with Lead and Copper Rule (LCR)
compliance. Depending on the magnitude of the pH drop, it may also affect the disinfection
efficiency of the secondary disinfectant as well. See Section 3.4 for more discussion of
disadvantages associated with lowering water pH. It is also possible that the removal or minerals
such as calcium can be so significant as to cause the water to taste significantly different to
customers, possibly generating customer complaints.
Recommendations for Addressing this Issue
The simplest way to avoid problems associated with a low pH is to adjust the pH after the
membranes. The fittings for the membrane unit, as well as any equipment between the
nanofiltration unit and the point where the pH is readjusted, should be made of materials that can
resist the lower pH of the water. Water systems should also adjust the alkalinity after
nanofiltration to prevent changes in pH in the distribution system that can enhance corrosion.
Passive treatment technologies, such as neutralizing filters or limestone contactors, are one way
to achieve a good pH and carbonate balance in membrane-treated waters.
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
Aeration may help to remove any sulfide or carbon dioxide accumulated as well as raise
oxygen levels to oxidize the sulfide to sulfate. Adding a disinfectant after the membranes can
also aid in oxidizing sulfide.
Another approach some systems have taken is to only pass part of the influent stream
through the NF unit and blend that NF product with water that has not received NF treatment.
However, this negates the microbial treatment credit of NF and would require an alternative
microbial treatment on the stream not treated by NF.
Issues with Reject Stream
Membrane processes produce a reject stream as well as backwash water. Therefore, the
amount of wastewater that has to be handled can be significantly higher than that produced
during conventional filtration. Although improvements have been made in efficiency, losing 10
to 20 percent of the process water as a waste stream is not unusual. The amount of process water
lost can be reduced by a second membrane unit in series with the first unit.
Due to the small pore size associated with nanofiltration, other feed water constituents
will also be removed. As a result, divalent salts, some metals, and some soluble organic carbon
may be concentrated in the waste stream. This may increase the cost associated with disposing
of the waste stream compared to disposal costs associated with MF, UF, and conventional
treatment processes. If regulatory limits or plant locations prohibit sending the waste stream to a
receiving body or wastewater treatment plant, costs for waste handling and disposal can be
substantial.
Recommendations for Addressing this Issue
To handle the higher quantities of waste water produced by nanofiltration units without
causing upset to the system, utilities may need to increase the capacity of their wastewater
storage and residuals processing facilities. This is especially true of systems that recycle their
reject water. If water is recycled, the Filter Backwash Recycling Rule (FBRR) requires that it be
recycled to the head of the plant unless the State approves an alternate location.
Water systems using nanofiltration will most likely need to increase the amount of water
they withdraw from their source to account for their process water losses. This could be an issue
in arid regions where water is scarce and water restrictions are in place.
Disposal of the reject stream to the ocean may be a good option since the salinity of brine
is typically not an issue. Otherwise systems will need to discuss the possibility of disposing of
the brine to the sanitary sewer which may have limits on brine or on certain metals and may
involve additional charges.
Additional Training Required
NF membranes are significantly different to operate than other water treatment units.
The control parameters are different; the State will determine the parameters that the system
must monitor to demonstrate regulatory compliance.
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
Recommendations for Addressing this Issue
Systems should consult with their state to determine what parameters will need to be
monitored for approval and regulatory compliance. Systems should also work with the state and
the vendor to provide adequate training for operators.
4.3.3 Recommendations for Gathering More Information
Read the Case Study
For more information on simultaneous compliance issues associated with nanofiltration
and how to address them, see Case Study #8 - Nanofiltration Membrane Technology for TOC
Removal starting on page B-43 of Appendix B. This case study describes the challenges faced
by one PWS switching to nanofiltration in response to growing demands for water and the
implementation of new drinking water standards. Specifically, the NF plant would facilitate the
removal of hardness, color, TOC, and its related chlorinated DBFs. The greatest operational
issue involved numerous leaks in the acid feed system, and sagging in the micron cartridge filter
housings and the string-wound filter.
See Additional References
Readers can turn to chapter 7 for further references on this topic. Section 7.1.1 contains
general references on water treatment, and section 7.1.10 contains references on membranes,
including NF.
Consider Additional Monitoring
The following are some suggestions for additional monitoring that may benefit water
systems implementing nanofiltration. Note that the purpose of these monitoring suggestions is
specifically to address and prevent potential simultaneous compliance issues. Water system
managers should discuss process control monitoring with the manufacturer of their nanofiltration
units or their engineer.
/ The pH of water leaving the nanofiltration unit should be monitored to ensure that 1)
CT is being calculated accurately; and 2) chemical dosages for corrosion control are
correct;
/ Hardness and alkalinity of water leaving the nanofiltration unit should be measured to
ensure that chemical dosages for corrosion control are correct;
/ TOC in the NF influent and effluent should be monitored to measure removal
effectiveness;
/ Particle counting should be conducted to indirectly monitor membrane integrity and
determine if a direct integrity test;
/ HPC should be measured in the NF effluent to identify breakthrough;
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
/ Membrane autopsies should be performed on any failed membranes to determine the
cause of failure and determine possible corrective actions; and
/ Taste and odor quality should be measured to ensure customer acceptance.
Consider Other Tools
In addition to water quality monitoring, there are additional tools available in Chapter 6
to help systems evaluate and improve their current water system in relation to the compliance
issues they may face when modifying their treatment operations. Examples of tools that can be
used when nanofiltration is used for Stage 2 DBPR compliance include:
• The AwwaRF report "Integrated Membrane Systems" (Schippers et al. 2004) that
provides guidance on the selection, design, and operation of an integrated membrane
system that can function as a synergistic system for removing microbiological
contaminants and DBF precursors;
• The AwwaRF report "Integrating Membrane Treatment in Large Water Utilities"
(Brown and Hugaboom 2004) that provides guidance on issues related to the
integration of low pressure membranes into larger water treatment facilities, including
membrane layout, piping, cost comparison, and operations and maintenance;
• The AwwaRF report "NOM Rejection by, and Fouling of, NF and UF Membranes"
(Amy et al. 2001) that provides information on the selection of appropriate
nanofiltration membranes to achieve high NOM rejection, and also presents
information on how water quality (such as the presence of calcium and pH) and
operational condition might affect NOM rejection by NF membranes;
• EPA's Environmental Technology Verification Program collects performance data on
many environmental technologies, including nanofiltration. Reports for each
technology can be found on the website at:
http://www.epa.gov/etv/verifications/verification-index.html;
• EPA's ICR Treatment Study Database contains the results of 36 pilot studies of
nanofiltration plants. It can be found on the web at:
www.epa.gov/safewater/data/icrtreatmentstudies.html;
• The second version of "Water Treatment Plant Model" (USEPA 200 li) developed by
EPA in 2001 that assists utilities to implement various treatment changes while
maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR;
and
• Various cost estimation models, such as WTCost©, 2003, that can be used to estimate
the cost of implementing a new membrane facility (see Section 6.3.7).
Readers are encouraged to read through Chapter 6 before making any final compliance decisions.
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
4.4 Other Microbial Removal Technologies
Other microbial removal technologies can be used
to meet LT2ESWTR requirements. All of the technologies
listed below use some type of filtration media to remove
Cryptosporidium oocysts and other microbes from drinking
water. The LT2ESWTR specifies minimum design and
implementation criteria for receiving various levels of
Cryptosporidium treatment credit. The LT2ESWTR
Microbial Toolbox Guidance Manual (USEPA N.d.e) will
provide additional guidance for each technology. The state should also be consulted on the
requirements for obtaining pathogen removal credit for these technologies. Although these
technologies are not expected to present significant compliance problems with other drinking
water regulations if implemented properly, there are operational issues that utilities should
consider if they use these options. These technologies are:
Bank Filtration
Bank filtration uses vertical or
horizontal wells drilled near a
riverbank. The riverbed and
material between the well and the
riverbank act as the filtration
media. It is generally used as
pretreatment for an existing
treatment plant.
The LT2ESWTR Toolbox Guidance
Manual \N\\\ provide more information
on the advantages and disadvantages
of different Cryptosporidium oocyst
removal technologies.
Improved Filter Performance
Improved filter performance results from optimizing existing filtration to achieve
consistently low filter effluent turbidity. In order to meet the lower finished water
turbidity requirements, systems need a high level of process control from the source
water intake to the filters. The Guidance Manual for Compliance with the IESWTR:
Turbidity Provisions (USEPA 1999d) discusses many design and operational aspects
water systems should consider for achieving low effluent turbidity.
Bag Filtration
Bag filtration is a pressure driven filtration process using a fabric filter media. Flow is
from inside the vessel to outside the vessel.
Cartridge Filtration
Cartridge filters are pressure driven filtration devices that have rigid or semi-rigid filter
media housed in pressure vessels. Water flows from outside the cartridge filter's vessel to
the inside.
Second Stage Filtration
Second stage filtration involves placing a second set of granular media filters in series
with an existing set of filters. The media can be rapid sand filters, slow sand filters, or
GAC filters.
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
Slow Sand Filtration
Slow sand filtration uses sand with a biologically active top layer as a filtration media
and gravity as the driver at relatively low loading rates.
Diatomaceous Earth Filtration
Diatomaceous earth (DE) filtration, often referred to as "pre-coat" filtration, uses a layer
of diatomaceous earth placed on a permeable cover or porous filter septum to filter water.
DE filters are operated as either pressure filters or vacuum filters.
This section briefly describes issues associated with the use of these technologies,
provides suggestions for addressing those issues, and recommends additional monitoring that can
be conducted.
4.4.1 Advantages
There are several advantages to these microbial removal technologies. The following
paragraphs list these advantages and briefly discuss which of these technologies provide each
advantage.
• Ease of use (bag filtration, cartridge filtration, bank filtration);
• Removal of Cryptosporidium and other pathogens (all technologies listed); and
• Removal of other contaminants/ DBF precursors (bank filtration, second stage
filtration, slow sand filtration).
Most operators are familiar with filtration. Second stage filtration, DE, and slow sand
filtration can all be easily implemented by any system familiar with conventional filtration.
Cartridge and bag filters are even easier to use as the only routine maintenance required is
replacing the cartridge or bag when a pre-set trigger is reached, either a pressure drop or a given
time.
All of these technologies will remove matter that is larger than the filter's effective pore
size. Therefore, in addition to Giardia cysts and Cryptosporidium oocysts, they will remove
some other microbial pathogens as well.
Some of these technologies can also be effective in removing DBF precursors and other
organic chemicals. Slow sand filtration can remove some DBF precursors. Second stage
filtration can offer additional DBF precursor removal, especially when GAC is used as the
second filter media. Bank filtration often provides additional DBF removal through biological
activity in the riverbank (Weiss et al. 2003).
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
4.4.2 Potential Operational and Simultaneous Compliance Issues
The disadvantages of these microbial removal technologies include:
• Hydraulic problems or scouring (all technologies listed);
• Clogging (cartridge filters, bank filtration);
• Increased residuals/ backwash (second stage filtration, increased filter
performance);
• Iron/manganese problems (bank filtration); and
• Filter fouling (bag filters, cartridge filters).
With careful planning, many of the disadvantages of these technologies can be overcome.
The following paragraphs briefly describe steps that can be taken to mitigate these
disadvantages.
Hydraulic Problems or Scouring
All of these technologies can add significant hydraulic head to a plant's hydraulic profile.
Changes in head, especially when filters are restarted, can disturb the filter and cause poor
performance.
Bank filtration can experience riverbank scouring during periods of high flow. The
riverbank scour can remove much of the finer grained sediment responsible for a portion of the
removal associated with this filtration method.
Large changes in flow to bag filters or intermittent operation can cause stress on the
seams of the bag filter and lead to premature failure.
Recommendations for Addressing this Issue
Hydraulic loss due to additional filtration can often be overcome by conducting a
hydraulic profile of the plant. Pumps can be installed to add additional head. The pumps should
be installed and operated in such a way as to not cause hydraulic disturbances to surrounding
processes, such as flocculation. Installing additional storage upstream of filtration is also a way
to smooth out hydraulic disturbances before they upset the filtration. Filtering to waste can
eliminate some of the problems associated with filter start-up.
Clogging
Bank filtration can also be subject to clogging by biomass growth in the pores or settling
of finer grained material in the pores. Although this may increase removal efficiency of
contaminants, it will increase pumping costs and drop yield. If too much coagulant is used
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
before cartridge filters, they can also clog, necessitating more frequent replacement and higher
costs.
Recommendations for Addressing this Issue
Some types of clogging in bank filtration can be avoided by proper siting of the wells.
Changes in chemistry in the aquifer that could precipitate minerals and areas of high
sedimentation should be avoided. Otherwise, some clogging is inevitable and even necessary.
Systems may have to account for this by designing for higher pumping rates than necessary or
installing multiple wells.
Increased Residuals or Backw ashing
Many of these technologies can create disposal problems. Cartridge and bag filters have
to be disposed of periodically. Second stage filtration will generate additional backwash water
and residuals that will need to be disposed. Practices to improve turbidity to increase filter
performance can also lead to increased residuals and backwash water. Systems considering
replacing their filter bed media as part of an effort to improve filter performance should consider
whether there will be challenges associated with the disposal of old media that may contain high
concentrations of metals or other contaminants.
If significant amounts of additional backwash and residuals are generated, a system may
need to change its residuals disposal procedures. This may include treating backwash water
through the addition of coagulant, or adding new sludge dewatering technologies or other
residuals handling equipment.
Recommendations for Addressing this Issue
To handle the higher quantities of process water produced by backwashing filter units,
systems may need to increase the capacity of their wastewater storage and residuals processing
facilities. This is especially true of systems that recycle their reject water. Manufacturers can
also be consulted for disposal recommendations for bag and cartridge membranes.
Iron and Manganese Problems
Bank filtration can result in elevated levels of iron and manganese if the portion of the
aquifer the wells draw from is anoxic. This will allow reduced manganese and iron to dissolve
and enter the water.
Recommendations for Addressing this Issue
If bank filtration is carried out through an anoxic zone, aeration may need to be added to
oxidize dissolved iron, manganese, and any other reduced chemical species that could cause
operational or aesthetic problems. Adding a pre-oxidant such as permanganate, ozone, or
chlorine can also oxidize iron and manganese.
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
Filter Fouling
Cartridge and bag filters can be fouled by biofilm if there is insufficient disinfectant
residual present to control the growth. This can increase the pressure loss across the filter and
shorten filter life.
Recommendations for Addressing this Issue
Adding disinfectant before the filters can prevent biofilm growth from clogging bag and
cartridge filters. Systems should evaluate the potential for DBF formation before taking this
step. Systems should also confirm that the filter media is compatible with the disinfectant.
4.4.3 Recommendations for Gathering More Information
See Additional References
Readers can turn to chapter 7 for additional references on this topic. Section 7.1.1
includes general references on water treatment, including filtration, Section 7.1.8 includes
references on enhanced coagulation and softening, and Section 7.1.11 includes references on
riverbank filtration.
Consider Additional Monitoring
Monitoring is important for determining the performance of these technologies. It can
provide a good indication of performance and help make operating determinations such as when
to backwash or replace filters.
-S Turbidity is used to determine filter performance as well as warn that a filter needs to
be backwashed. Monitoring of individual and combined filter effluents is required
for conventional filters. Even if the filter is installed as a second filter or in series
with another treatment technology, turbidity monitoring should be conducted;
•S Particle counters can also provide useful information, and can frequently determine
breakthrough before turbidity measurements can;
S Flow measurements help to spot potential hydraulic upset and adjust loading rates
appropriately;
S Pressure measurements are used to indicate how frequently a system needs to
backwash or whether filter media needs to be replaced; and
•S Streaming current detectors can be used to detect the charge on particles and optimize
coagulant dose.
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4. Installing new Total Organic Carbon or Microbial Removal Technologies
Consider Other Tools
In addition to water quality monitoring, there are additional tools available in Chapter 6
to help systems evaluate and improve their current water system in relation to the compliance
issues they may face when modifying their treatment operations. Examples of tools that can be
used when implementing the other microbial removal technologies described in this section
include:
* The AwwaRF report "Evaluation of Riverbank Filtration as a Drinking Water
Treatment Process" (Wang, Hubbs and Song 2002) that provides general information
on the design and operation of a riverbank system that can be used for the removal of
DBF precursors and microbial contaminants;
* EPA's Environmental Technology Verification Program collects performance data on
many environmental technologies, including diatomaceous earth, cartridge, and bag
filters. Reports for each technology can be found on the website at:
http://www.epa.gov/etv/verifications/verification-index.html:
• The second version of "Water Treatment Plant Model" (USEPA 200 li) developed by
EPA in 2001 that assists utilities with implementing various treatment changes, while
maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR;
• Various cost estimation models that can be used to estimate the costs of designing,
constructing, and operating one of the technologies described above (see Section
6.3.7) ;and
• The Partnership for Safe Water has many resources available for optimizing filter
performance. More information can be obtained at their website at:
http://www.awwa.org/science/partnership/.
Readers are encouraged to read through Chapter 6 before making any final compliance decisions.
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5 Alternative Disinfection Strategies
As discussed in previous chapters, some water systems, after improving and optimizing
current operations, will still need to install a new type of treatment to comply with the Stage 2
DBPR and LT2ESWTR. Some systems may consider switching to an alternative disinfectant for
either primary or residual disinfection (or both). This chapter describes potential simultaneous
compliance issues associated with using any of the following alternative disinfectants:
• Chloramines
• Ozone
• Ultraviolet light (UV)
• Chlorine dioxide
Suggestions are also provided for how systems can
mitigate simultaneous compliance and operational
issues that are identified.
In addition, Section 5.5 of this chapter
discusses different possible combinations of primary
and residual disinfectants, and simultaneous
compliance issues that may arise as a result of using
the disinfectants in combination.
ALTERNATIVE DISINFECTION
STRATEGIES COVERED
• Chloramine
• Ozonation
• Ultraviolet Light
• Chlorine Dioxide
• Primary and Residual
Disinfectant Use
5.1 Chloramines
Chloramines are formed when free chlorine reacts with ammonia and may be present as
monochloramine, dichloramine, and/or trichloramine. The chloramine compounds react more
slowly than free chlorine and as a result, they form fewer DBFs and are more persistent in the
distribution system. Some studies have shown that chloramine compounds can penetrate
biofilms more effectively than free chlorine. Monochloramine is generally considered the
preferred species for disinfection purposes because of its biocidal properties, relative stability,
and infrequent taste and odor problems (Kirmeyer et al. 2004a). Because monochloramine is a
weaker disinfectant than free chlorine, it is more frequently used as a residual disinfectant in the
distribution system. If not properly controlled, the use of chloramines can lead to nitrification
episodes in the distribution system and may cause taste and odor issues, loss of disinfectant
residual, and other problems.
5.1.1 Advantages of Chloramines
The use of chloramination to comply with the Stage 2 DBPR presents numerous benefits
in terms of implementation and operation. Advantages include:
• Lower DBF formation
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5. Alternative Disinfection Strategies
• More persistent than free chlorine residuals
• Biofilm control in the distribution system
• May reduce occurrence ofLegionella
Lower DBF Formation
Compared to free chlorine, chloramines react more slowly with organic matter resulting
in lower concentrations of total trihalomethane (TTHM) and haloacetic acid (five) (HAAS).
Although detectable concentrations of mono- and dichloroacetic acids can be produced, these are
generally significantly lower than corresponding concentrations produced by free chlorine.
Replacing chlorine with chloramines as a secondary disinfectant typically reduces TTHM levels
40 to 80 percent. Depending on the system's water quality, the actual TTHM reduction can vary
from 10 to 95 percent (Kirmeyer et al. 2004a).
If chlorine is added to the water before ammonia, the byproducts associated with the use
of free chlorine can be formed, although additional formation will be significantly retarded once
the ammonia has been added. Because free chlorine is a much more effective disinfectant for
viruses, surface water systems generally add chlorine early enough in the treatment train so that
CT requirements for viruses are achieved before the ammonia is added.
More Persistent than Free Chlorine Residuals
Chloramines have a lower oxidation-reduction potential and a slower reaction time than
free chlorine, so they are less likely to be consumed by reactions with organics and reduced
metals. Therefore, they are longer lasting in the distribution system and are generally more
persistent than a free chlorine residual. This characteristic helps to protect distribution system
water quality, particularly in areas with long detention times. It also helps maintain compliance
with the Surface Water Treatment Rule (SWTR)'s requirement to maintain a disinfectant
residual.
Biofilm Control in the Distribution System
Studies have shown that chloramine compounds are better able to penetrate the biofilm
layer and inactivate attached organisms because they are more limited than chlorine in the types
of compounds with which they will react (USEPA 1992a; Jacangelo, Olivieri, and Kawata 1987).
LeChevallier, Cawthorn, and Lee (1988a, 1988b) found that chloramines were more effective at
inactivating biofilm organisms than free chlorine. LeChevallier, Lowry, and Lee (1990) also
found that, in iron pipes, 3 to 4 mg/L doses of free chlorine did not control biofilm growth.
Chloramines, however, did control biofilm growth at doses starting at 2 mg/L. Recent research
suggests that the factors affecting biofilm growth and disinfection are complicated and may
depend on many factors, thus varying between systems (Olios, Huck, and Slawson 2003).
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5. Alternative Disinfection Strategies
May Reduce Occurrence of Legionella
Use of monochloramine in water supplies may reduce the occurrence of Legionella
bacteria and incidence of Legionnaires' disease. Flannery et al. (2006) conducted a 2-year study
to evaluate whether converting from chlorine to monochloramine for water disinfection would
decrease Legionella colonization of hot water systems. Water and biofilm samples from 53
buildings were collected for Legionella culture during 6 intervals. Legionella colonized 60% of
the hot water systems before monochloramine versus 4% after conversion. The effectiveness of
chloramines for inactivating Legionella and biofilm bacteria may be related to its ability to
penetrate the biofilm (Kirmeyer et al. 2004a).
5.1.2 Potential Operational and Simultaneous Compliance Issues Associated
with Chloramines
Potential issues associated with the use of chloramines include:
• Nitrification
• Increased corrosion and metal release
• Taste and odor issues
• Weaker disinfectant
• Blending issues - chloraminated and chlorinated waters
• Safety concerns
• Issues with ozonation and GAC filtration
• Issues for dialysis patients, fish owners, and industrial customers
Nitrification
Biological nitrification is the oxidation of ammonia to nitrite and then eventually to
nitrate by bacteria and other organisms. Nitrification adversely impacts the effectiveness of
chloramines by increasing the chloramine demand, depleting chloramine residuals and thus
allowing bacterial regrowth (Kirmeyer et al. 2004a). A loss of disinfectant residual in the
distribution system can result in a violation of the SWTR, and may lead to increased
vulnerability to contamination. Other adverse effects of nitrification on distribution system
water quality include:
• Decrease in dissolved oxygen
• Increase in nitrite and nitrate levels
• Decrease in pH
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5. Alternative Disinfection Strategies
• Decrease in alkalinity
• Decrease in ORP
Systems that chloraminate can experience nitrification episodes under certain system
conditions including but not limited to:
• Excess free ammonia
• Low chloramine residual
• Long water detention times in the distribution system, such as in storage tanks, areas
with low demand, and dead ends
• Water temperatures of 25°C - 30°C (Wolfe et al. 1988; Wolfe et al. 1990)
• A pH in the range 7.0 to 8.0 is optimum for nitrifying bacteria (Kirmeyer et al. 2004a)
As part of the TCR review process, EPA has published several white papers on issues in
the distribution system such as nitrification and biofilm growth. These papers can be found at:
http://www.epa.gov/safewater/disinfection/tcr/pdfs/whitepaper tcr nitrification.pdf
http://www.epa.gov/safewater/disinfection/tcr/pdfs/whitepaper tcr biofilms.pdf
The AwwaRF report, Optimizing Chloramine Treatment, Second Edition (Kirmeyer et al.
2004a) describes the biochemistry of nitrification, its impacts on distribution system water
quality, and treatment and control strategies. It also describes relevant utility experiences based
on a project survey and case studies.
Recommendations for Addressing this Issue
Nitrification may be controlled by taking certain preventative measures and by
implementing corrective actions when monitoring indicates the onset of a nitrification event.
Preventive measure for controlling nitrification were identified in a recent AwwaRF
survey by 50 water systems that use chloramination (Kirmeyer et al. 2004a). The most important
preventive measures include:
• Distribution system flushing
• Increasing chloramine residual
• Modifying chlorine-to-ammonia nitrogen ratio
Additional preventive methods used by survey respondents include maintaining low
concentrations of residual ammonia at the treatment plant effluent, using a source water with the
lowest temperature whenever possible, and modifying distribution system hydraulics to
minimize water age (e.g. improve water circulation, eliminate dead-ends, open valves, increase
turnover rate in storage facilities).
Some systems that chloraminate periodically switch to free chlorine disinfection for a few
weeks or months to reduce the population of nitrifying bacteria in the distribution system.
However, a recent AwwaRF study (Vikesland et al. 2006) found that".. .a periodic switch from a
chloramine residual to a free chlorine residual may not be sufficient for long-term control of
nitrification within a chloraminated distribution system. Given the higher levels of DBFs
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5. Alternative Disinfection Strategies
observed following a switch to free chlorine, utilities may be better served by careful
maintenance of their ammonia feed such that nitrification episodes are minimized."
Monitoring programs specific to nitrification should be developed and implemented.
The AwwaRF report, Guidance Manual for Monitoring Distribution System Water Quality
(Kirmeyer et al. 2002) provides detailed monitoring protocols for nitrification including
recommended sampling locations, monitoring parameters, and sampling frequencies.
Monitoring protocols are provided for proactive monitoring to establish a baseline database and
investigative monitoring in response to a suspected nitrification event. The recommended
monitoring parameters for the baseline monitoring program include total chlorine,
monochloramine, free ammonia, total ammonia, nitrite, nitrate, HPCs, and water residence time.
The investigative monitoring program includes these parameters plus temperature and dissolved
oxygen. Monitoring locations may include raw water, point-of-entry to the distribution system,
reservoir inlets/outlets, coliform monitoring stations, selected dead-end sites, and low flow sites,
depending on the monitoring objective (baseline vs. investigative) and the monitoring parameter.
In combination with monitoring protocols, Kirmeyer et al. (2002) recommend
establishing system-specific action levels that will trigger corrective action. For example,
Kirmeyer et al. (2004) summarized the nitrification action plan for Irvine Ranch Water District
that included three action levels. In Level 1, a nitrite level of 25 to 49 jig/L triggered a review of
system operations and additional sampling. In Level 2, an HPC count of 200-500 cfu/mL, a total
chlorine residual <0.4 mg/L or a nitrite level of 50 to 74 |ig/L triggered additional sampling,
additional analyses for nitrate and free ammonia, and reservoir cycling. Level 3 was triggered by
an HPC count >500 cfu/mL, a total chlorine residual <0.2 mg/L or a nitrite level >75 |ig/L, and
involved chlorinating and cycling the reservoir, and continued sampling.
Corrective actions that may be implemented when a nitrification event is occurring were
also identified in the AwwaRF survey (Kirmeyer et al. 2004a). Pipe flushing was found to be the
most effective corrective action. Additional corrective methods identified by survey respondents
include:
• Blending low-TOC water which possesses a higher and more stable chloramine
residual with nitrifying water (effective in small tanks);
• Combining pipe flushing and monitoring until adequate water quality is re-
established; and
• Modifying distribution system hydraulics (eliminate dead-ends).
Increased Corrosion and Metal Release
Nitrification resulting from the use of chloramines can lower the alkalinity and the pH of
the water in the distribution system. This can prove detrimental for lead and copper control.
Corrosion products and tubercles also interfere with the disinfection of coliform and
heterotrophic bacteria, which can lead to increased microbially-induced corrosion.
Changing from free chlorine to chloramines in the distribution system could potentially
impact the stability of pipe scales, particularly redox-sensitive minerals such as lead, copper,
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manganese, and iron. Changes in the solubility and/or permeability of scale materials could
possibly result in their desorption and release into the bulk water.
For example, systems with lead service lines could possibly see changes in lead levels as
a result of a switch to chloramines. Pipe scale analysis has shown that, in some distribution
systems where free chlorine is used, the corrosion by-products on lead service lines contain
significant amounts of lead (IV) oxide compounds (Schock 2001; Schock, Wagner and Oliphant
1996; AwwaRF and DVGW-Technologiezentrum Wasser 1996; Lytle and Schock 2005; Schock
and Giani 2004; Schock et al. 2005). Lead (IV) oxide scales are highly oxidized and considered
to be relatively insoluble in water. If a water system switches from a strong oxidant (chlorine) to
a weaker oxidant (chloramines), the ORP necessary to maintain lead (IV) stability may no longer
remain. As a result, lead (IV) compounds may be reduced to more soluble lead (II) solids and a
subsequent increase in lead concentrations in water may be observed.
The switch to chloramines following historically high levels of chlorine residual (and
relatively high oxidation reduction potential as described above), along with the absence of a
reevaluation and modification to corrosion control treatment, is the suspected cause of the LCR
action level exceedances experienced by Washington, D.C.'s Water and Sewer Authority
(DCWASA) beginning in 2002. DCWASA made the conversion from free chorine to
chloramines in late 2000 with the goal of reducing TTHM and HAAS levels in the distribution
system. After the conversion to chloramines, elevated lead levels were found in compliance
samples from homes with lead service lines. To address the lead corrosion problem, the city
accelerated its lead service line replacement program and began orthophosphate treatment in
August 2004. The treatment program was successful in reducing elevated lead levels. LCR
monitoring results for 2005 and 2006 showed that the calculated 90th percentile values were at or
below the lead action level.
There have been some indications that chloramines can corrode brass. Edwards et al.
(2004) found accelerated brass corrosion in 7 of 8 brass samples tested, and a slight increase with
chloramines as opposed to free chlorine. Reiber et al. (1993) did not observe any additional
corrosion of brass in the presence of chloramines above what was seen with free chlorine.
Ammonia is known to be corrosive to brass and it is possible that excess ammonia and nitrate,
caused by nitrification, can accelerate brass corrosion. Uchida and Okuwaki (1999) found lead
corrosion (lead is a component of brass) to be higher in the presence of ammonia and nitrate
together. Maas et al. (2005) found that fluoridation of water in combination with chloramines
can cause accelerated brass corrosion.
Chloramines have also been found to be corrosive to some elastomer materials.
Prolonged exposure of elastomer materials, such as those used in gaskets and valve seals, can
lead to cracking and loss of integrity (Reiber 1991). Although free chlorine can also cause
corrosion of these materials, chloramines show significantly higher corrosion rates. A recent
study of chloramine effects on elastomer materials (Bonds 2004) showed that pipe gaskets made
with vulcanized elastomers do not corrode significantly due to their low surface area to volume
ratio, even though it was shown that chloramine causes significant corrosion of vulcanized
elastomers. Components with higher surface area to volume ratios such as flappers or valve
seats may experience more significant deterioration. Both Reiber (1991) and Bonds (2004)
found that fluorocarbon elastomers showed the least corrosion of the elastomers tested.
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Therefore, using fluorocarbon elastomers in components that will receive high exposure to
chloramines will help prevent failure.
Recommendations for Addressing this Issue
Reiber (1993) noted that materials deterioration by monochloramine is less noticeable
than by dichloramine. Therefore, maintaining optimal conditions for monochloramine formation
may help prevent materials deterioration as well as help control nitrification. Optimal conditions
for monochloramine include pH of 8.3, a temperature of 25°C, and a 4:1 to 5:1 weight ratio of
chlorine to ammonia (Kirmeyer et al. 2004a).
Systems can minimize lead corrosion by:
• Optimizing the pH, alkalinity, and DIG of the water; and
• Adding a corrosion inhibitor (i.e., a substance that is phosphate- or silica-based) to the
finished water to form a protective coating on the pipes.
Systems concerned with brass corrosion can take steps to limit free ammonia and
nitrification as listed in the section on nitrification. The steps listed above will also help mitigate
brass corrosion.
To prevent elastomer corrosion, components such as gaskets and flappers should be made
of elastomers such as fluorocarbons that have good resistance to chloramines. Education and
outreach programs can help customers select the appropriate materials.
Taste and Odor Issues
Chlorine-based disinfectants have some associated taste and odor impacts.
Monochloramine has a higher odor threshold and variations in residual concentrations produce
less noticeable odors than free chlorine. Dichloramine and trichloramine, however, have much
stronger odors than either monochloramine or free chlorine (Krasner and Barrett 1985). Taste
and odor problems can also arise from nitrification episodes caused by excess ammonia. Control
measures to prevent nitrification are discussed earlier in this section.
Recommendations for Addressing this Issue
To prevent the formation of dichloramine and trichloramine that cause taste and odor
problems, the chlorine to ammonia ratio should be carefully controlled and pH should be kept
above 7.0. When the chlorine to ammonia ratio exceeds 5:1, dichloramine frequently begins to
form. In general, maintaining a ratio between 3:1 and 5:1 should minimize odor problems.
Blending Chloraminated and Chlorinated Water
When water with a chloramine residual is mixed with water with a free chlorine residual,
the chlorine to ammonia ratio changes and the resulting changes in distribution system water
quality may cause customer complaints and/or possible violations of SDWA regulations. If the
additional free chlorine raises the ratio to higher than 5:1, dichloramine and trichloramine can
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form which have low odor thresholds and can cause customer complaints. If the ratio is raised to
7.6:1 or higher by the additional free chlorine residual, breakpoint reactions can occur.
Breakpoint reactions can lead to a total loss of disinfectant residual, which can result in a
violation of the SWTR and possibly the TCR if the residual loss lasts long enough for an
increase in microbial growth throughout the system. Blending could also cause the water to have
excess free chlorine, causing DBF formation and a possible violation of the DBPR.
Recommendations for Addressing this Issue
To avoid breakpoint chlorination, utilities mixing waters with chloramines and free
chlorine residuals should determine the residuals in both waters and determine the chlorine to
ammonia ratio of the resulting mixture. Some systems have developed computer models to
predict these ratios. The models should be calibrated to the specific distribution system in order
to be useful. Keeping the chlorine to ammonia ratio below 5:1 in the chloraminated water, which
allows an ammonia residual to exist, will allow some addition of water with a chlorine residual
before problems occur. A system could also choose to add ammonia again at the point where the
waters are mixed to maintain the chlorine to ammonia ratio in the proper range. In either case,
the water system also needs to take into account the possibility of excess ammonia causing
nitrification. Careful monitoring of excess ammonia, free chlorine, and total chlorine residuals
should be carried out to ensure that appropriate ratios are maintained.
Weaker Disinfectant
Monochloramine is a weaker disinfectant than free chlorine as illustrated by the required
CT values to achieve inactivation of viruses and Giardia cysts (Exhibit 5.1). Both chlorine and
monochloramine are ineffective against Cryptosporidium oocysts.
Exhibit 5.1 Comparison of Required CT (mg-min/L) values for Inactivation of
Viruses and Giardia by Free Chlorine and Monochloramine at pH 7 and 10°C
Disinfectant
Chlorine
Monochloramine
2-log
inactivation
(99%) of
viruses
3
643
4-log
inactivation
(99.99%) of
viruses
6
1,491
0.5-log
inactivation
(68.4%) of
Giardia
171
310
3.0-log
inactivation
(99.9%) of
Giardia
1041
1,850
1 CT values are for free chlorine of <0.4 mg/L
Even at relatively high doses of monochloramine, extremely long residence times are
required to achieve required levels of inactivation for viruses and Giardia cysts. Systems that
switch from free chlorine to monochloramine as their primary disinfectant must benchmark for
virus and Giardia inactivation.
Recommendations for Addressing this Issue
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Systems can compensate for the lower disinfecting power of monochloramine by using a
different disinfectant as the primary disinfectant and using monochloramine to maintain a
disinfectant residual in the distribution system. Frequently this is done by adding the ammonia
some time after the chlorine has been added. This allows a period of time for free chlorine
disinfection. While this scheme will result in higher DBFs than using chloramines as the
primary disinfectant, it will still result in lower DBF concentrations than when free chlorine is
used as both a primary and residual disinfectant. One water system found as little as two minutes
of free chlorine contact time prior to ammonia addition achieved desired inactivation results and
reduced TTHM by 50 percent over free chlorine alone (Means et al. 1986). Another system used
an hour of free chlorine contact time before converting to chloramines without exceeding TTHM
regulatory levels (Gianatasio 1985).
Systems with very high TOC may wish to avoid free chlorine altogether. These systems
can switch to a different primary disinfectant such as ozone, UV, or chlorine dioxide. See
Sections 5.2, 5.3, and 5.4 for more details on these disinfectants, and their advantages and
drawbacks.
Safety Concerns
Various safety issues should be considered when switching to chloramines, depending on
the type of ammonia used. High concentrations of ammonia can form an explosive mixture of
trichloramine when it reacts with chlorine. Ammonia gas is also toxic if released to the
atmosphere in sufficient concentrations. Ammonium sulfate does not have as many safety issues
as either anhydrous ammonia or aqueous ammonia, but it is considerably more expensive and
should be kept dry to avoid feed problems.
Recommendations for Addressing this Issue
To avoid the possibility of an explosive reaction between bulk chlorine and bulk
ammonia, the two chemicals should be stored in separate rooms. Feed points and pipes for
chlorine and ammonia should also be placed at least five feet apart (USEPA 1999b).
To avoid the release of ammonia into the atmosphere, several precautions should be
taken. Anhydrous ammonia should be stored in pressurized containers away from temperature
extremes (temperatures greater than 125°F will cause pressure buildups in the tank). Aqueous
ammonia tanks should be vented to keep pressure from building up from ammonia volatilization.
Keeping the temperature low will also help to prevent volatilization, which can cause vapor lock
in pumps. Buildings where ammonia is stored should be well-ventilated and should include
storage areas for respirators just outside the ammonia storage area. If large amounts of ammonia
are stored, an emergency scrubber should also be installed. Additional safety precautions are
detailed in the report, Optimizing Chloramine Treatment, 2nd ed. (Kirmeyer et al. 2004a).
Issues with Ozonation and GAC Filtration
Wilczak et al. (2003) found that ozone use prior to chloramination increases the
assimilable organic carbon concentration and could destabilize the chloramine residual, leading
to problems with chloramine residual concentrations at the ends of the distribution system.
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5. Alternative Disinfection Strategies
Adding chloramines before a GAC filter may lead to nitrification in the GAC filter. It
has been found that a reaction between chloramines and GAC may free up ammonia and
encourage the growth of ammonia oxidizing bacteria in the GAC filters (Tokuno 1999).
Recommendations for Addressing this Issue
Installing a GAC filter after ozone to remove AOC, then allowing a few minutes of free
chlorine contact time to oxidize any remaining organics before ammonia is added can be a more
reliable way to allow the formation of a stable chloramine residual. Chloramines should not be
added prior to GAC filters.
Issues for Dialysis Patients, Fish Owners, and Other Customers
Chloramines can be toxic to dialysis patients and must be removed before water is used
in dialysis machines. Chloramines are also toxic to fish and therefore must be removed from the
water before it is used for pet fish or before water is discharged to natural fish habitats. The
removal of chloramines from tap water is more difficult to achieve, and more costly, than free
chlorine. This also impacts water customers who produce foods, beverages, and
Pharmaceuticals.
Recommendations for Addressing this Issue
Because the process for removing chloramines is different from that for removing
chlorine, dialysis patients and fish owners should be notified in advance of the switch to
chloramines. Water systems may also want to consider adding special notification language for
fish owners and dialysis patients in their consumer confidence reports, so that the information is
provided on an annual basis. Information on how other systems conducted community outreach
before, during, and after treatment with chloramines are presented in the AwwaRF document,
Optimizing Chloramine Treatment, Second Edition (Kirmeyer et al. 2004a).
5.1.3 Recommendations for Gathering More Information
Read Case Studies
Three case studies in Appendix B address simultaneous compliance issues for systems
that switched to chloramines as part of an effort to reduce DBF concentrations:
• Case Study #9 - Modifying Chlorandnation Practices to Address Nitrification
Issues on page B-51 describes a surface water system serving 115,000 people that
took steps to control nitrification in the distribution system after switching to
chloramines;
• Case Study #13 - Chlorine Dioxide for Primary Disinfection and Chloramines for
Secondary Disinfection on page B-75 describes a surface water treatment plant in a
wholesale system serving seven municipalities and approximately 92,000 people.
The treatment plant switched from chlorine to chlorine dioxide as its primary
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5. Alternative Disinfection Strategies
disinfectant and from chlorine to chloramines for residual disinfection. In addition,
the system uses chlorine dioxide intermittently as a pre-oxidant in its raw water.
Among the challenges the system has encountered is being able to achieve sufficient
Cryptosporidium inactivation to be granted LT2ESWTR credit and still comply with
the Stage 1 DBPR's chlorite MRDL; and
• Case Study #14 - Chlorine Dioxide for Primary Disinfection and Chloramines for
Secondary Disinfection on page B-81 describes a small surface water system that
achieves its required CT with chlorine dioxide and maintains its disinfectant residual
in the distribution system with chloramines.
See Additional References
Readers can find more references on this topic listed in the following sections of
Chapter 7:
• Section 7.1.1 includes general references on water treatment
• Section 7.1.2 includes references on controlling DBF formation
• Section 7.1.3 includes several references on corrosion/disinfection interrelationships
• Section 7.1.5 includes references on using distribution system BMPs to control water
quality in the distribution system.
• Section 7.1.12 includes additional references on chloramines.
Of particular note, the new publication Fundamentals and Control of Nitrification in
ChloraminatedDistribution Systems (M56), published by AWWA in 2006, provides background
information on the occurrence and microbiology of nitrification and offers current and practical
approaches to nitrification prevention and response.
Consider Additional Monitoring
Additional monitoring may benefit water systems using chloramines to address and
prevent potential simultaneous compliance issues. Specific guidelines on monitoring to detect
potential nitrification events is discussed previously in Section 5.1.2.
Consider Other Tools
Additional tools listed in Chapter 6 may help systems evaluate and improve their current
water system in relation to the compliance issues they may face when modifying their treatment
operations. Readers are encouraged to read through Chapter 6 before making any final
compliance decisions. The following AwwaRF reports provide additional information:
• Optimizing Chloramine Treatment, Second Edition (Kirmeyer et al. 2004a) describes
chloramine chemistry, the advantages and disadvantages of chloramination, an
approach for evaluating conversion to chloramines, and design and implementation
issues for chloramine feed systems. It also describes relevant utility experiences
based on a project survey and case studies.
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• Internal Corrosion of Water Distribution System (AwwaRF and DVGW-
Technologiezentrum Wasser 1996) provides bench-scale and pilot testing protocols
that can be used to evaluate changes in corrosion potential due to the switch to
chloramines.
• Optimizing Corrosion Control in Water Distribution System (Duranceau, Townley,
and Bell 2004) provides techniques for instantaneous corrosion monitoring.
• Tools and Methods to Effectively Measure Customer Perceptions (Colbourne 2001)
describes tools that allow utilities to measure customer perceptions and changes in
their opinions toward the use of chloramines.
• Water/Wastewater Costs, Windows Version 3.0, (Wesner 2000) provides capital and
O&M cost calculations for various water treatment processes based on user inputted
design parameters.
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5.2 Ozonation
Ozone is a powerful chemical disinfectant and an alternative to free chlorine. It is an
unstable gas that is generated on-site, using either air or liquid oxygen. It is very effective at
disinfecting many microbes and as a pre-oxidant. It can, however, convert bromide to bromate, a
DBF regulated by the Stage 1 D/DBPR. It also oxidizes organic matter into smaller molecules,
which can provide a more easily degradable food source for microorganisms in the distribution
system. Because of its instability in water, ozone cannot be used to provide a disinfectant
residual in the distribution system. Furthermore, ozone can produce odor compounds such as
aldehydes and ketones.
5.2.1 Advantages of Ozonation
The main advantages of ozone are:
• Effective against pathogens
• Does not form chlorinated DBFs
• Effective pre-oxidant
• Can oxidize taste and odor compounds
• Can raise UV transmittance of water and UV disinfection effectiveness
• Independent of pH
• Can aid coagulation
Effective Against Many Microbes
Ozone is a highly effective disinfectant because of its high oxidation potential. It is the
strongest of all the commonly used chemical disinfectants. It is most effective against viruses
and slightly less effective against Cryptosporidium oocysts. As with most chemical
disinfectants, the degree of microbial inactivation is temperature dependent. Inactivation is
greater at higher temperatures.
Exhibit 5.2 shows the required CT values at 10°C for inactivation of various microbes for
each of the commonly used chemical disinfectants. Comparing the CT values shows the relative
effectiveness of the disinfectants.
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Exhibit 5.2 Required CT values (mg-min/L) for Chemical Disinfectants at 10°C
Disinfectant
Ozone
Chlorine1
Chlorine
Dioxide
4-log
Inactivation
(99.99%) of
Viruses
1
6
4.2
3-log
Inactivation
(99.9%) of
Giardia
1.43
104
23
1-log Inactivation
(99.9%) of
Cryptosporidium
9.9
N/A
277
Source: USEPA 2003a
N/A - these disinfectants are ineffective against Cryptosporidium
1 at pH = 7.0 and chlorine residual = 0.4 mg/L
The exhibit shows that ozone is the most effective disinfectant against all three microbes
listed. In addition to satisfying microbial disinfection requirements, ozone can aid in compliance
with the Stage 2 DBPR by eliminating chlorine as a primary disinfectant and lowering the
required dose of secondary disinfectant. Systems with DBF concentrations above a certain
threshold that switch to ozone from another primary disinfectant are required by the IESWTR,
LT1ESWTR, and LT2ESWTR to benchmark for Giardia, Cryptosporidium, and viruses. More
details on disinfection profiling and benchmarking can be found in the Disinfection Profiling and
Benchmarking Guidance Manual (USEPA 1999a).
Does Not Form Chlorinated DBFs
Ozone by itself does not form chlorinated DBFs. Therefore, using ozone instead of
chlorine for primary disinfection can lower DBF formation and aid in compliance with the Stage
2 DBPR. Ozone can react with bromide, however, to form bromate, which is a non-chlorinated
DBF with an MCL of 10 ppb set under the Stage 1 D/DBPR (see section 5.2.2 of discussion of
bromate formation).
Effective Pre-oxidant
Ozone's high oxidation potential also means it acts well as a pre-oxidant. It can be used
to oxidize iron and manganese so they can be removed through coagulation and sedimentation.
Ozone can oxidize arsenic (III) to arsenic (V) which enhances its removal. Many organic
compounds are oxidized by ozone as well. If the dose is high enough, ozone can even
completely mineralize some organics, lowering the concentration of DBF precursors and aiding
in Stage 2 DBPR compliance.
Can Oxidize Taste and Odor Compounds
Ozone is especially useful in oxidizing taste and odor compounds such as geosmin and 2
-methylisoborneol (MIB). The efficiency of ozone at degrading geosmin and MIB is further
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increased if hydrogen peroxide is added in addition to the ozone, a process referred to as
peroxone.
Raises UV Transmittance of Water
Low UV transmittance (UVT) of the water will result in less efficient UV disinfection.
Ozone treatment before UV can oxidize those compounds that absorb UV, thereby increasing
transmittance and UV's disinfection effectiveness. Although it may be cost-prohibitive to install
both UV and ozone, a system with one of the two technologies in place may benefit from
installation of the other. This arrangement would require either chlorine or chloramines to
maintain a distribution system residual.
Independent ofpH
The disinfection efficiency of ozone, unlike chlorine, does not depend on pH for the
range of pH values normally encountered in water treatment. This enables plants to adjust pH to
optimize coagulation, prevent corrosion, or alter DBF formation reactions without losing
disinfection capability. It also removes some of the seasonal variability that is usually found in
disinfection benchmarks. Note, however, that bromate formation is impacted by the pH of the
water. This is discussed in more detail in Section 5.2.2.
Can Aid Coagulation
Some systems have reported improvements in coagulation when they added ozone prior
to coagulation (Reckhow et al. 1993, Stolarik and Christie 1997). Other systems have found no
change or even increases in filtered water turbidity after ozonation. The interaction between
ozonation and coagulation is complex and entails the interaction of many parameters. Therefore,
results will vary significantly from plant to plant. Systems should conduct bench-scale and
preferably pilot-scale tests to determine how ozone will affect the systems water quality. Note
that adding ozone after coagulation and sedimentation may have the advantage of lowering
ozone demand allowing the same CT with a lower ozone dose.
5.2.2 Potential Operational and Simultaneous Compliance Issues Associated
with Ozonation
The main operational and simultaneous compliance issues associated with ozone are:
• May form bromate
• Forms smaller organic compounds
• Does not provide a residual in the distribution system
• May increase dissolved oxygen in the water
• Can form taste and odor compounds
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• Can increase corrosion
• Ozone bubbles can hinder filter performance
• Switching to ozone with biological filtration may cause manganese release from
filters
• Requires additional training
This section summarizes these issues and provides recommendations for some ways to
address them.
May Form Brornate
If bromide is present in the source water, it can react with ozone to form bromate. In the
presence of organic matter, ozone can also form brominated THMs and HAAs. The Stage 1
D/DBPR requires compliance with a 10 [ig/L MCL for bromate. Therefore, systems considering
installing ozone should evaluate whether compliance with the bromate MCL may be an issue.
Whether bromate or brominated organic DBFs form depends on the pH and organic
content of the water. Lower pH water and high DOC concentrations tend to favor the formation
of brominated organic compounds. Systems using ozone may be able to reduce their chlorine
dose, however, and as a result improve compliance with TTHM and HAAS MCLs. Higher pH
and low dissolved organic concentration generally lead to greater bromate formation.
Recommendations for Addressing this Issue
There are several techniques that public water systems can use to control disinfection
byproduct formation when bromide ion is present. These include:
• Optimizing the pH
• Keeping the ratio of ozone to DOC low
• Adding ammonia
Lowering the pH favors formation of brominated organic compounds over bromate.
Performing ozonation at a pH below 7 will lower the formation of bromate. This is a particularly
good option for systems that have low DOC concentrations and do not have problems with high
TTHM or HAAS concentrations in their finished water. If DOC concentrations are high,
however, this method of bromate control may result in exceeding HAAS or TTHM MCLs.
Systems also need to consider other effects of lowering pH such as increased corrosion, impacts
on the effectiveness of secondary disinfectants, and impacts on coagulation. (See Section 3.4 for
a more complete discussion of the effects of changing pH.)
If the ratio of ozone to DOC is kept low, the formation of bromate and brominated
organic compounds can be reduced. This can be done by either lowering the ozone dose or by
lowering DOC concentrations. Lowering the ozone dose would mean increasing the contact
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time, unless the system currently achieves more than the required CT. The ability to extend the
contact time will depend on the ozone demand and decay of the water as well as operational
limitations. Determining the ozone demand and decay rate of a given water before ozone is
installed will help determine the possibilities of this option. DOC can be lowered by removing it
prior to the ozone addition. If a system does not need to use ozone for pre-oxidation, it may
want to add the ozone after sedimentation, or even after filtration, to achieve a lower ozone to
DOC ratio. It is not typical, however, to ozonate after filtration, because of higher AOC
concentrations being introduced into the distribution system and the related problems of TCR
compliance and nitrification that may occur. If a system needs to pre-oxidize, a small dose of
ozone can be added to the raw water and a higher dose can be added after sedimentation or
filtration. Using biological filtration in this case can be especially effective for lowering DBFs,
since biological filtration tends to remove aldehydes and other small organic compounds that can
make up a large fraction of the DOC after ozonation.
Adding ammonia to water containing bromide and ozone will lead to bromamine
formation. Bromamines react more slowly with organic matter and form fewer brominated
organic compounds and less bromate. Ammonia addition, however, can lead to nitrification
problems in the distribution system. See Section 5.1 for more details on controlling nitrification
when ammonia is added.
Systems with high bromide concentrations, especially those with high DOC as well, may
not be able to use ozone even if they adopt these mitigation methods. Systems that use ozone to
inactivate Cryptosporidium may have an especially hard time, in this regard, because
Cryptosporidium requires a much higher ozone dose. Since the LT2ESWTR does not grant
disinfection credit for an ozone residual in the first contact chamber, many systems will want to
increase their ozone dose to help them gain CT in subsequent chambers. Bromide can be
removed by the use of anion exchange, but this is generally not a cost-effective solution.
Forms Smaller Organic Compounds
Ozone breaks down organic compounds into smaller chain organic molecules, especially
aldehydes and ketones. These smaller organic molecules often measured as "assimilable organic
carbon" (AOC) are more readily biodegradable and can increase biological growth downstream
of the ozone addition point. AOC is a measure of the organic carbon readily available as food
for microorganisms. Some systems that have added ozone without biological filtration have
experienced increased AOC and microbial growth in the distribution system (Van der Kooij
1997). Increased biological growth in the distribution system can lead to higher disinfectant
demand and potentially TCR violations. Biological growth can also cause increased corrosion,
possibly leading to violations of the Lead and Copper Rule (LCR) as well as to taste and odor
problems.
Recommendations for Addressing this Issue
An effective way to reduce AOC is biological
filtration. Biological filtration can be achieved by not
having a disinfectant residual in the water entering the
post-ozone filter. The increased dissolved oxygen that
results from the ozonation, combined with the high surface
An effective way to
remove smaller organic
compounds is biological
filtration.
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5. Alternative Disinfection Strategies
area per volume of the filter media, provide conditions for biological growth to occur on the
filters. The biological growth on the filters then consumes the AOC, using it as a food source.
Biological filtration has been shown to lower AOC effectively, even when very short residence
times are used. Longer residence times can lead to the reduction of other organic compounds as
well (LeChevallier et al. 1992). See Urfer et al. (1997) for more details on biological filtration.
Any type of filter media can accommodate biological filtration. Slow sand filters, rapid
rate dual media filters, and GAC filters have all been successfully used for biological filtration.
Rapid rate filters have been shown to remove AOC, though they may not remove all of the
biodegrable dissolved organic carbon (BDOC), which is a portion of organic matter that can still
be used by microbes as a food source but takes longer for the microbes to metabolize than AOC.
Slow sand filters and GAC contactors have been shown to remove both BDOC and AOC. GAC
has the added benefit that it will adsorb or concentrate organics, thus extending the time
available for the microbes to metabolize the organic matter.
Switching to biofiltration can present its own challenges. Although biofilters remove
turbidity as well as other filters, they have shown higher particle counts than traditional filters.
They have also shown increased headloss over traditional filters. Systems switching to
biofiltration may want to consult the AwwaRF report "Optimizing Filtration in Biological
Filters" (Huck et al. 2000) to design the best biofiltration system.
Does Not Provide a Disinfectant Residual in the Distribution System
Ozone reacts very quickly and therefore is not able to provide a residual for use in the
distribution system. A secondary disinfectant is, therefore, required to maintain a disinfectant
residual in the distribution system as required by the SWTR.
Recommendations for Addressing this Issue
Chlorine can often be used as an effective residual disinfectant after ozonation. Since
ozone is used to achieve primary disinfection, lower doses of chlorine can be used as a secondary
disinfectant, resulting in lower DBF levels. Ozone followed by biological filtration reduces DBF
precursors, which also leads to lower DBF levels. If biological filtration is not used, the system
should be careful that the additional smaller organic molecules do not react with chlorine added
as a secondary disinfectant to produce higher DBF concentration than if chlorine alone were
added. Chloroform has been found to be higher in some systems which used ozone without
biological filtration than it was before ozone was implemented.
Chloramines can also be used to provide a distribution system residual after ozonation.
Chloramines will result in lower DBFs than chlorine. As mentioned above, adding ammonia
with the ozone will provide benefits regarding the formation of brominated DBFs. If this
approach is taken, chlorine can be added after filtration to form the chloramines. For a full
discussion on the benefits and drawbacks of chloramines as a secondary disinfectant, see Section
5.1.
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5. Alternative Disinfection Strategies
May Introduce Dissolved Oxygen into the Water
When ozone reacts in water it forms dissolved oxygen. This oxygen may remain
dissolved in the water. Dissolved oxygen can increase corrosion of metals. It can also cause
increased growth of aerobic bacteria and problems with TCR compliance.
Recommendations for Addressing this Issue
Corrosion-resistant materials should be used in the ozone feed equipment, the contact
chamber, and any other plant equipment that comes into contact with the water after ozonation
and before the dissolved oxygen is dissipated. The best way to prevent dissolved oxygen from
entering the distribution system is to run the filters in biologically active mode. This will lower
the dissolved oxygen, as well as remove AOC.
Systems using ozone after filtration and unfiltered systems may need to take steps to
control microbial growth in the distribution system. Control measures include ensuring a
sufficient residual throughout the system, looping dead ends in the distribution system, and
minimizing retention time in reservoirs. Systems may also want to raise the pH of the water or
add a corrosion inhibitor to prevent corrosion.
Can Form Taste and Odor Compounds
Ozone is generally very effective in destroying taste and odors compounds, but in some
cases ozonation of organic matter forms aldehydes and other compounds that can impart tastes
and odors to water.
Recommendations for Addressing this Issue
Systems should consider using a GAC filter or biologically active filtration to help
eliminate aldehydes formed during ozonation, before the water reaches customers.
Increases Corrosion
Ozone is corrosive and can corrode steel pipes and fittings, concrete, rubber gaskets, and
other material with which it comes into contact in the treatment plant.
Recommendations for Addressing this Issue
All material that comes into contact with ozone residual should be resistant to ozone.
This includes any equipment which might be exposed to off-gassed ozone. Equipment
manufacturers should be contacted to ensure compatibility of their equipment with ozone.
Ozone Bubbles Can Hinder Filter Performance
Ozone can de-gas in the filter and bind to the filter media. This can adversely affect filter
performance and reduce the effectiveness of filter backwashing.
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5. Alternative Disinfection Strategies
Recommendations for Addressing this Issue
If ozone is injected under pressure, it should be de-gassed before the filters.
Switching to ozone and biological filtration may cause release of manganese from filters
Iron-based coagulants often contain significant amounts of manganese as an impurity in
the coagulant. When systems that use iron coagulants also pre-chlorinate, a layer of oxidized
manganese can form on the filter media surface. If the system switches to ozone and stops pre-
chlorinating to achieve biological filtration, this manganese has been found to reduce and be
released into the filtrate water (Wert et al. 2005, Gabelich et al. 2005). Therefore systems which
are using or have historically used iron coagulants and switch from chlorine to ozone before the
filter in order to take advantage of biofiltration may experience elevated manganese levels. In
some cases these levels of manganese have violated secondary standards for manganese
(Gabelich et al. 2005).
Recommendations for addressing this issue
Wert et al. (2005) found that the release of manganese from filters was much more at
rapid at pH 6 than at pH 8. Therefore, maintaining a pH near 8 going through the filter may
prevent elevated manganese levels. Switching to a coagulant with lower manganese impurity
concentrations will help future manganese releases but will not solve any already accumulated
manganese problems. One system found that they were able to clean the manganese from
anthracite media using a two step process involving acid and hydrogen peroxide (Gabelich et al.
2005). This process, however, did not remove manganese from sand media. Another option is
to replace the filter media.
Requires Additional Training
Ozone disinfection is an advanced technology and requires different procedures and
equipment compared to conventional technologies. There are also safety issues, such as
containment and destruction of ozone off-gas.
Recommendations for Addressing this Issue
Additional training will be needed to ensure that operators can use equipment correctly.
They will need to become familiar with additional chemicals used for ozone quench. Operators
should also be aware of safety concerns related to off-gassing and destruct units.
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5. Alternative Disinfection Strategies
5.2.3 Recommendations for Gathering More Information
Read Case Studies
Two case studies in Appendix B describe simultaneous compliance challenges faced by
utilities using ozone.
Case Study #10 - Ozonation on page B-57 describes a surface water system serving
approximately 115,000 people that installed ozone to control both Cryptosporidium and
disinfection byproducts. The system was concerned about how ozone might result in increased
AOC in its finished water, so biofiltration was also installed to address potential problems that
could have arisen in the distribution system as a result.
Case Study #11 — Ozonation and Biological Filtration on page B-65 describes a system
that significantly expanded its capacity at the same time that it installed ozone. Its source is a
river with high TOC, so this system was also concerned with ozone's impact on AOC levels in
the finished water. Four new biological filters were installed and 12 existing filters were
converted to biological filtration.
See Additional References
Readers can turn to Chapter 7 for more references on this topic. Section 7.1.1 includes
general references on water treatment, Section 7.1.2 includes references on controlling DBF
formation, and Section 7.1.13 includes references on Ozone.
Consider Additional Monitoring
The following are some suggestions for additional monitoring that may benefit water
systems using ozone. The purpose of these monitoring suggestions is specifically to address and
prevent potential simultaneous compliance issues. Water system managers should discuss
process control monitoring with the manufacturer of their ozonation units or their engineer.
•S Dissolved organic carbon (DOC) measurements in water being ozonated, and
calculation of the ozone:DOC ratio. By keeping the ozone:DOC ratio low, formation
of bromate and brominated organic compounds can be reduced;
•S AOC and/or BDOC monitoring after biological filtration to verify that they are being
removed reliably;
-S If there is no biological filtration treatment step, AOC and/or BDOC monitoring of
finished water before it enters the distribution system to track whether levels are high
enough to cause problems with biofilm growth;
-S HPC measurements at locations throughout the distribution system and in plant
effluent, to watch for increased biofilm growth;
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5. Alternative Disinfection Strategies
S Dissolved oxygen at points after ozonation in the treatment plant, as part of an effort
to control levels and limit corrosion in the plant;
S Dissolved oxygen at entry points to the distribution system to make sure it has been
reduced to acceptable levels and will not induce distribution system corrosion;
•S Taste and odor in finished water since ozonation can create off-odors; and
S Ozone residual in the contactor to ensure proper CT, and after the contactor to ensure
proper removal and safety.
Consider Other Tools
In addition to water quality monitoring, there are additional tools available in Chapter 6
to help systems evaluate and improve their current water system in relation to the compliance
issues they may face when modifying their treatment operations. Examples of tools that can be
used when ozone is used for Stage 2 DBPR compliance include:
• The "Guidance Manual for Monitoring Distribution System Water Quality"
(Kirmeyer et al. 2002) which can be used to assist water utilities in implementing a
distribution system water quality data collection and analysis program;
• The AwwaRF report "Internal Corrosion of Water Distribution System" (AwwaRF
and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot
testing protocols that can be used to evaluate changes in corrosion potential due to the
switch to ozonation;
• The AwwaRF report "Optimizing Corrosion Control in Water Distribution System"
(Duranceau, Townley, and Bell 2004) which provides techniques for instantaneous
corrosion monitoring;
• EPA's Environmental Technology Verification Program collects performance data on
many environmental technologies, including ozone. Reports for each technology can
be found on the website at: http://www.epa.gov/etv/verifications/verification-
index.html;
• Water/Wastewater Costs, Windows Version 3.0, (Wesner 2000) which provides
capital and O&M cost calculations for various water treatment processes based on
user inputted design parameters.
• The AwwaRF report "Water Utility Self-Assessment for the Management of
Aesthetic Issues" (McGuire et al. 2004) which can be used to guide utilities in
conducting self-assessment of taste and odor issues caused by ozonation and to
identify subsequent control strategies;
• The AwwaRF report "Tools and Methods to Effectively Measure Customer
Perceptions" (Colbourne 2001) which describes tools that allow utilities to measure
customer perceptions and changes in their opinions toward the use of ozonation;
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5. Alternative Disinfection Strategies
• The AwwaRF report "Ozone-Enhanced Biofiltration for Geosmin and MIB Removal"
(Westerhoff et al. 2005) which describes the removal of taste and odor compounds
through the use of biological filtration; and
• EPA's Microbial Toolbox Guidance Manual (USEPA N.d.e) which describes
technologies which can be used for compliance with the LT2ESWTR. The manual
describes advantages and disadvantages for each technology and lists design and
operating considerations.
Readers are encouraged to read through Chapter 6 before making any final compliance decisions.
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5. Alternative Disinfection Strategies
5.3 Ultraviolet Light (UV)
Recent research indicating that UV light can inactivate Cryptosporidium
at relatively low lamp intensities has spurred interest in its use for drinking
water disinfection. UV light works by damaging the genetic material of
microorganisms, interfering with the ability of pathogens to replicate and
therefore with their ability to be infective. Similar to chemical disinfectants, the
extent of UV inactivation depends on the intensity of the light and the time the
microorganism is exposed to it. UV is an effective way to disinfect without
producing regulated DBFs. UV does not provide a residual, however, so it is
not effective in providing a distribution system residual. Extensive information on the
mechanisms of UV disinfection and recommendations on UV system design, validation, and
operation are provided in the UV Disinfection Guidance Manual (USEPA 2006b).
If UV is being used as a toolbox option to comply with LT2ESWTR, UV reactors must
be validated according to state guidelines and operate within the validated parameters. For
purposes of design and operation, EPA recommends that systems strive to deliver the required
UV dose at all times during treatment (USEPA 2006b).
5.3.1 Advantages of UV
Advantages
UV light's advantages include:
• It can inactivate chlorine-resistant pathogens such as Cryptosporidium oocysts
and Giardia cysts at relatively low doses;
• It does not produce regulated DBFs; and
• Its effectiveness is not pH or temperature dependent.
Inactivates Cryptosporidium and Giardia
UV disinfection gained attention in the U.S. drinking water market when it was shown
that it could inactivate Cryptosporidium oocysts and Giardia cysts. This gives UV an advantage
over chlorine or chloramines, which are ineffective against Cryptosporidium. If properly tested
and validated, UV is one of the least expensive options for systems that are required to achieve
additional Cryptosporidium inactivation under the LT2ESWTR (USEPA 2006b). UV can also
meet SWTR requirements for Giardia inactivation.
Does Not Produce Regulated DBFs
UV disinfection, as a photochemical process, does not produce any of the regulated
byproducts that chemical disinfectants such as chlorine, ozone, and chlorine dioxide produce.
Surface water systems and systems using GWUDI of surface water may meet Stage 2 DBPR
requirements by switching to UV disinfection and lowering their doses of chemical disinfectants.
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5. Alternative Disinfection Strategies
Systems making this change will be required to benchmark their disinfection process under
LT2ESWTR requirements before making the change. See Section 5.3.2 for further discussion of
UV benchmarking requirements. Systems will also need to continue to meet the residual
disinfection requirements of the SWTR.
NotpHor Temperature Dependent
Research has shown that temperature effects on UV dose-response are minimal (USEPA
2006b). Dose response is also independent of pH in the range of 6 to 9 (Malley 2000). This
gives systems more flexibility to adjust pH to control coagulation, or to lower production of
DBFs without also affecting disinfection efficiency. This could also mean simpler operations if
the UV dose does not need to be adjusted seasonally (although dose could vary seasonally if the
levels of UV absorbing compounds in the water being treated vary seasonally).
5.3.2 Potential Operational and Simultaneous Compliance Issues Associated
with UV Disinfection
Potential operational and simultaneous compliance issues associated with UV
disinfection include:
• Substances in water can interfere with UV disinfection
• Hydraulic upsets can lower the delivered dose and possibly cause lamp breakage
• Much higher doses are needed for virus inactivation
• UV disinfection provides no distribution system residual
• Power quality problems can disrupt disinfection
• Requires additional training
This section provides brief descriptions of these issues and suggestions for addressing them.
Substances in Water Can Interfere with UV Disinfection
Because UV disinfection relies on UV light interacting with the organism's genetic
material to be effective, any substance that either absorbs or refracts the germicidal UV light can
interfere with disinfection. A common measure of the fraction of germicidal light (i.e., light
specifically with a wavelength of 254 nanometers) transmitted through a material is UV
Transmittance (UVT). The higher the UVT, the better UV light can be transmitted through the
water and the more effective the treatment. Compounds in source waters that can absorb or
refract UV light and reduce UVT include humic and fulvic acids, phenols, metals (e.g., iron and
manganese), and anions (e.g., nitrates) (USEPA 2006b). The LT2ESWTR requires water
systems to account for UV absorbance of the water during validation testing.
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5. Alternative Disinfection Strategies
In addition to absorbing UV light and decreasing UVT, compounds in the water can foul
the external surfaces of the lamp sleeves. The rate of fouling depends on water quality
characteristics such as hardness, alkalinity, ion concentration, and pH.
The presence of disinfectants upstream of UV treatment can impact UV performance.
Ozone is a strong absorber of UV light and can interfere with disinfection if not quenched prior
to UV treatment. Ozone treatment, however, can be effective in increasing the UVT. Some
chlorine residual can be lost if water with a free or total chlorine residual is passed through a UV
reactor (USEPA 2006b).
Recommendations for Addressing this Issue
Systems should carefully evaluate their water quality during the planning phase for their
new UV facility. UVT is the most important water quality characteristic affecting UV facility
design (USEPA 2006b); therefore, care should be taken to characterize UVT during typical
operations as well as during storm events, seasonal changes, reservoir turnover, and source water
blends. UV absorbance of the water (i.e., UVT) must be accounted for during validation testing.
EPA recommends that systems determine a "fouling factor" during the planning phase to
account for lower UVT caused by fouling of the lamp sleeves (USEPA 2006b). This factor is
defined as the estimated fraction of UV light passing through a fouled sleeve compared to a new
sleeve. UV reactors typically allow for cleaning of lamp sleeves to remove deposited material.
Three common approaches are off-line chemical cleaning, on-line mechanical cleaning, and on-
line mechanical-chemical cleaning. More frequent lamp cleaning can increase the fouling factor.
Lamp fouling should be accounted for during validation testing.
Systems can modify their treatment to increase UVT and reduce the potential for fouling
of lamp sleeves. Pre-oxidation and enhanced coagulation are potential treatments that can be
used for this purpose. Their usefulness should be evaluated on a case-by-case basis.
Ozone, if used for taste and odor control, will generally be added before the filters and
will not enter the UV reactor. If this is not the case and an ozone residual is present in the water
before it enters the UV unit, the ozone should be quenched. Ozone can be quenched by air
stripping in the last chamber of the ozone contactor, or by using a reducing agent such as
hydrogen peroxide. Some studies suggest, however, that ozone quenching using hydrogen
peroxide can be slow in low-alkalinity water (National Research Council 2000). The ozone
residual should not be quenched with thiosulfate, as thiosulfate also absorbs UV.
If chlorine dioxide is being used, it should be added after the UV reactor. See Section 5.4
for further details on chlorine dioxide use. If corrosion inhibitors that contain UV-absorbing
compounds are used, they should be added after water has passed through the UV reactor.
Lamp Breakage
Lamp breaks can be caused by debris in water, temperature variations, water hammer,
electrical surges, or improper installation (USEPA 2006b). Lamps in most UV reactors contain
mercury or an amalgam of mercury and another compound such as gallium or indium. If lamps
break during reactor operations, there is a risk of exposure to mercury.
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5. Alternative Disinfection Strategies
Recommendations for Addressing this Issue
Very few incidents of on-line lamp breaks have been documented. Appendix E of the
Ultraviolet Disinfection Guidance Manual (USEPA 2006b) provides design and operating
recommendations to minimize the occurrence of breaks and to develop written procedures to be
followed if a break does occur. To isolate the mercury, systems can install spring-return actuated
valves with a short closure time on the reactor inlet and outlet piping. Systems should also
consider installing a strainer or mercury trap. EPA recommends that systems evaluate the
applicability of various isolation techniques on a case-by-case basis.
Virus Inactivation
While UV disinfection is highly
effective against protozoa such
as Cryptosporidium oocysts, it
is less effective against viruses.
While UV disinfection is highly
effective against protozoa such as
Cryptosporidium, it is less effective against
viruses. The LT2ESWTR requires systems
considering substituting current
chlorination with UV disinfection to
benchmark with respect to viruses, Giardia, and Cryptosporidium and consult with the state to be
sure that sufficient inactivation is maintained.
Exhibit 5.3 shows the ratio of CT required for inactivation of viruses and the CT required
for the inactivation of Cryptosporidium for chlorine dioxide and ozone. This ratio can be
compared to the ratio of UV dose required for inactivation of viruses and the UV dose required
for the inactivation of Cryptosporidium. This ratio is much lower for chlorine dioxide and ozone
compared to UV, meaning that chlorine dioxide and ozone are more effective for inactivation of
viruses compared to Cryptosporidium, while UV is the opposite.
Exhibit 5.3 Ratio of CT values for Inactivation of Viruses and Cryptosporidium at
10°C
Disinfectant
Chlorine
dioxide
Ozone
UV1
Ratio of Virus Inactivation to Cryptosporidium Inactivation
Ratio of 2-log virus inactivation
(99.0%) CTto0.5-log
Cryptosporidium inactivation CT
(68.4%)
0.03
0.10
17.2
Ratio of 4-1 og virus inactivation
CT(99.99%)to3.0-log
Cryptosporidium inactivation CT
(99.9%)
0.03
0.03
15.5
UV doses are in mJ/cm and are calculated using safety factors based on the use of low pressure mercury lamps.
They may vary depending on the reactor validation method. See the Ultraviolet Disinfection Guidance Manual
(USEPA 2006b) for details.
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5. Alternative Disinfection Strategies
Recommendations for Addressing this Issue
Systems that adopt UV disinfection will need to take special care to ensure that the virus
benchmark is achieved. The state should be consulted throughout the planning process to ensure
that inactivation requirements can be met to achieve the necessary credit.
To receive credit for disinfection with UV light, the LT2ESWTR requires water systems
to demonstrate through validation testing that the UV reactor can deliver the required UV dose.
The testing must determine a range of operating conditions that can be monitored by the system
and under which the reactor delivers the required UV dose. At the time of this publication, EPA
is not aware of an available challenge microorganism that allows for full-scale testing of UV
reactors to demonstrate 4-1 og inactivation of viruses at a required dose of 186 ml/cm2.
Methodologies for challenge testing at doses necessary to inactivate UV resistant viruses may be
developed in the future.
Until then, UV technology should be used in a series configuration or in combination
with other inactivation or removal technologies to provide a total 4-1 og treatment of viruses.
The second option uses a different treatment to achieve virus inactivation and uses UV only for
Cryptosporidium and Giardia inactivation. If a chemical disinfectant is used, it could be added
after the UV reactor to maintain a residual in the distribution system or it could be added prior to
the UV reactor where it could also serve as a preoxidant. Surface water systems will need to add
secondary disinfection to comply with the entry point and distribution system residual
requirements of the SWTR. If a second disinfectant is used also for additional virus inactivation,
it must achieve the required inactivation before the first customer. Chlorine will provide virus
inactivation with a relatively low dose, but may produce DBFs and could create problems with
Stage 2 DBPR requirements. Chloramines will have less DBF formation but will require
significantly longer contact time in the clearwell to ensure appropriate inactivation before the
first customer. See Section 5.1 for more details on the use of chloramines.
If pre-oxidation is practiced, chlorine, ozone, or chlorine dioxide can be used. Chlorine
may not be an attractive solution because the production of DBFs. Ozone will likely be cost
prohibitive unless it is already installed; in which case it would have numerous advantages.
UV Does Not Provide a Residual
UV disinfection, because it is not a chemical disinfectant, does not leave a residual and
cannot be used to meet SWTR requirements regarding entry point and distribution system
residuals.
Recommendations for Addressing this Issue
Free chlorine or chloramines can be used to maintain a residual disinfectant. Chlorine is
effective against viruses and bacteria but can cause significant problems with Stage 2 DBPR
compliance, especially in portions of the distribution system with long residence times where
organic carbon is present. Chloramines as a residual disinfectant after UV disinfection have the
potential to provide adequate distribution system residual and very low DBFs. Problems with
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chloramines include potential issues with nitrification, potential corrosion problems, and taste
and odor issues if the chlorine-to-ammonia ratio is not maintained properly.
Power Quality Problems Can Disrupt Disinfection
A UV lamp can loose power in the event of a power interruption, voltage fluctuation, or
power quality anomaly. Common causes of power quality problems include faulty wiring and
grounding, weather-related damage, and power transfers to emergency generators or alternate
feed (USEPA 2006b). Systems are required to monitor lamp status to ensure that reactors are
operating within validated limits. Loss of power can result in the reactors operating off-
specification.
Recommendations for Addressing this Issue
Systems should determine if their facility(s) experience power quality problems or is
located in a remote area where power quality is unknown. If power quality may be a problem,
EPA recommends that systems perform a power quality assessment to quantify and understand
the potential for off-specification operation. Power quality assessments include contacting local
power suppliers to obtain data on power quality and reliability, obtaining information on the
power quality tolerance of the UV equipment under consideration, determining how long it will
take UV reactors to function at full power after a power quality event, and determine if backup
power or power conditioning equipment is needed (USEPA 2006b).
Requires Additional Training
Because UV reactors are operated differently than conventional chemical disinfection,
training may be needed to ensure proper operation, monitoring, reporting, and maintenance of
the UV disinfection equipment.
Recommendations for Addressing this Issue
Equipment vendors and state officials should be contacted early in the process regarding
the appropriate training for UV disinfection. Systems considering UV should check with their
state to determine whether state-specific monitoring requirements.
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5.3.3 Recommendations for Gathering More Information
Read Case Study
Case Study # 12 — Ultraviolet Disinfection on page B-71 in Appendix B describes a
surface water system with a 16 MGD plant that converted from chlorine to UV treatment to
achieve its CT. The system uses a large river as its source and needed to reduce its DBFs. In
anticipation of LT2ESWTR, it opted for UV because of the additional benefit that UV
inactivates Cryptosporidium. One of the biggest challenges the system faced with the transition
was providing the training needed to operate and maintain the UV system. This case study
describes how the system addressed this and other issues it encountered as one of the first surface
water systems of its size to switch over to UV.
See Additional References
Readers can turn to Chapter 7 for further references on this topic. Section 7.1.1 includes
general references on water treatment, section 7.1.2 includes references on controlling DBF
formation, and section 7.1.14 includes references on UV disinfection.
Consider Additional Monitoring
The following are some suggestions for additional monitoring that may benefit water
systems implementing UV disinfection. The purpose of these monitoring suggestions is
specifically to address and prevent potential simultaneous compliance issues. Monitoring should
be done before the design process to allow for proper design of the system. Water system
managers should discuss process control monitoring with the manufacturer of their UV units,
their engineer, and other experienced utilities.
•S Monitoring for UV absorbance, which is very important for UV disinfection
performance and is required by the LT2ESWTR
•^ Periodic measurements of inorganic and organic chemicals, as applicable, in the
water entering the UV unit. Tracking their concentrations will help a system make
sure levels are low enough and will not interfere with UV disinfection. Some
compounds with this potential are:
- Iron
- Manganese
- Calcium
- Magnesium
- Aluminum
- Dissolved Organic Carbon
- Ozone
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Consider Other Tools
In addition to water quality monitoring, there are additional tools listed in Chapter 6 that
could help systems evaluate and improve their current water system in relation to the compliance
issues they may face when modifying their treatment operations. Examples of tools that can be
used when UV is used for Stage 2 DBPR compliance include:
• The "Ultraviolet Disinfection Guidance Manual" (USEPA 2006b) which provides
guidance on the validation, selection, design, and operation of UV disinfection
systems;
• The AwwaRF report "Integrating UV Disinfection Into Existing Water Treatment
Plants" (Cotton 2005) which provides user-friendly web tools that will assist utilities
in assessing important disinfection decisions and UV implementation issues;
• The AwwaRF report "Full Scale Implementation of UV in Groundwater Disinfection
Systems" (Malley 2002) which provides specific guidance for the selection, design,
and operation of UV systems; and
• Various cost estimation models that can be used to estimate the cost of implementing
a new UV facility.
Readers are encouraged to read through Chapter 6 before making any final compliance decisions.
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5. Alternative Disinfection Strategies
5.4 Chlorine Dioxide
Chlorine dioxide is an alternative chemical disinfectant
that can be used to lower DBF production while maintaining
adequate levels of inactivation. Because it is unstable, it is
generated onsite using chlorine dioxide generators.
Chlorine dioxide has gained popularity because it
produces relatively few THMs and HAAs. It is also very
effective against bacteria, viruses, and Giardia cysts, and can
provide some inactivation of Cryptosporidium oocysts at higher
temperatures. The main drawback of chlorine dioxide is that the chlorine dioxide MRDL of 0.8
mg/L combined with an MCL of 1.0 mg/L for chlorite, the main byproduct of chlorine dioxide,
limit the dose that can be applied. In addition, low water temperatures can make it more difficult
to use chlorine dioxide.
5.4.1 Advantages of Chlorine Dioxide
Chlorine dioxide's advantages include:
• Effectively inactivates bacteria, virus, and Giardia cysts; can achieve some
Cryptosporidium oocyst inactivation;
• Less TTHM and HAAS formation than chlorine;
• Effective oxidant for the control of iron, manganese, hydrogen sulfide, and
phenolic compounds;
• May treat high-bromide, high-TOC waters better than chlorine or ozone; and
• Not significantly affected by pH values between 6 and 9.
Effective Disinfectant
Chlorine dioxide is a strong oxidant and can therefore effectively inactivate a wide range
of microbes. Exhibit 5.4 compares the required CT values of chlorine dioxide with those of
chlorine and ozone. Chlorine dioxide is slightly less effective than chlorine against viruses and
bacteria, but is more effective against Giardia and Cryptosporidium.
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5. Alternative Disinfection Strategies
Exhibit 5.4 Required CT Values for Inactivation of Microorganisms by Chlorine
Dioxide Compared with Other Chemical Disinfectants at 10°C and pH 6-9 (in mg-
min/L)
Microbe
Viruses
Viruses
Giardia
Giardia
Cryptosporidium
Cryptosporidium
Inactivation Level
2-log (99.0%)
4-log (99.99%)
0.5-log (68.4%)
3.0-log (99.9%)
0.5-log (68.4%)
3.0-log (99.9%)
Chlorine Dioxide
4.2
25.1
4
23
138
830
Chlorine1
3
6
17
104
N/A
N/A
Ozone
0.5
1.0
0.23
1.43
4.9
30
Source: USEPA2003a
N/A - not applicable. Chlorine is ineffective against Cryptosporidium.
1 - Chlorine CT values for pH 7
Chlorine dioxide can achieve some inactivation of Cryptosporidium oocysts. Required
CT levels for Cryptosporidium inactivation are relatively high though, so achieving more than a
half log inactivation is unlikely given restrictions on dose. See the following section for a further
discussion of dose restrictions. Chlorine dioxide can, however, be a relatively low cost
alternative for systems that require a 0.5 log Cryptosporidium inactivation to comply with the
LT2ESWTR.
Less TTHM and HAAS Formation
Chlorine dioxide provides a good alternative to chlorine for systems that wish to lower
the formation of TTHM or HAAS. Pure chlorine dioxide does not form significant amounts of
TTHM or HAAS. Most chlorine dioxide generators do produce some chlorine as a byproduct,
however, so some TTHM and HAAS will still be formed. The DBF of greater concern when
chlorine dioxide is used is chlorite, which has a 1.0 mg/L MCL. See the discussion in the
following section for more information on minimizing chlorite formation. Systems
contemplating changing to chlorine dioxide will be required to perform a disinfection benchmark
for viruses, Giardia, and Cryptosporidium and consult with the state to ensure adequate
disinfection levels are maintained.
Effective Oxidant
Another advantage to chlorine dioxide is that it is a strong oxidant. It can effectively
oxidize many compounds including iron and taste and odor compounds. Under the right pH
conditions it can oxidize arsenic, which is often the first step in arsenic treatment. Oxidation of
arsenic does not alone result in the removal of arsenic from water, but it enhances its removal
during additional treatment. Systems that were previously using chlorine to pre-oxidize these
chemicals may be able to achieve the same goals using chlorine dioxide, and simultaneously
reduce TTHM and HAAS to comply with the Stage 2 DBPR.
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5. Alternative Disinfection Strategies
Not Significantly Affected bypH
The efficiency of chlorine dioxide does not vary significantly in the pH range of 6 to 9.
This benefits systems trying to meet benchmarks since the CT achieved will not vary with pH.
This also gives systems more flexibility with their treatment. They can adjust pH values to
improve coagulation, reduce corrosion, or reduce DBF formation without concern for losing
disinfection efficiency. It is possible, however, that some plants using enhanced coagulation or
enhanced softening may fall outside the pH range of 6 to 9. See the following section for further
discussion of these cases.
5.4.2 Potential Operational and Simultaneous Compliance Issues Associated
with Chlorine Dioxide Use
Potential issues with using chlorine dioxide include the following:
• Forms chlorite, a regulated DBF
• Reduced effectiveness at low temperature
• Chlorine dioxide MRDL of 0.8 mg/L
• Can form brominated DBFs
• Degrades when exposed to UV light
• Residual dissipates quickly
• Potential odor problems
• Requires additional training and safety concerns
This section addresses these issues and provides recommendations for addressing them.
Chlorite Formation
One of the biggest disadvantages of using chlorine dioxide as a disinfectant is that it
forms chlorite. The MCL for chlorite was set at 1.0 mg/L by the Stage 1 D/DBPR. Systems
using chlorine dioxide must monitor daily at the entrance to the distribution system for chlorite.
They must also collect 3 chlorite samples per month in the distribution system. As much as 70
percent of the chlorine dioxide added to water can break down to form chlorite. This limits the
dose of chlorine dioxide that can be used and therefore the amount of inactivation that can be
achieved. This especially limits Cryptosporidium inactivation, since the required CT values for
Cryptosporidium are much higher than for other microbes.
High oxidant demand and high pH also lead to higher chlorite production. If there is
substantial oxidant demand in a system's water due to natural organic matter (NOM) or reduced
metals, the oxidant demand will consume the chlorine dioxide and form chlorite, but the chlorine
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5. Alternative Disinfection Strategies
dioxide consumed in this way will not achieve any disinfection. Systems then have to add higher
chlorine dioxide doses to achieve sufficient inactivation, and as a result generate higher chlorite
concentrations.
Water pH values above 9 also lead to
increased production of chlorite. Systems
with high pH as a result of enhanced
softening or corrosion control may have
trouble complying with the chlorite MCL.
One of the biggest disadvantages of
using chlorine dioxide as a
disinfectant is that it forms chlorite.
Recommendations for Addressing this Issue
There are several ways to minimize chlorite concentrations. Adding chlorine dioxide
after the filters, after the oxidant demand has been reduced, can result in lower chlorite
concentrations. In order to comply with the LT1ESWTR or IESWTR, systems must benchmark
and check with the state before moving the point of disinfection. Systems using chlorine dioxide
as a pre-oxidant may also reduce the water's oxidant demand by using pre-sedimentation before
chlorine dioxide is injected.
Systems that increase pH during treatment should try to do so after the chlorine dioxide
contact chamber. They may want to reduce the treated water's pH to below 9 before adding the
chlorine dioxide.
Even if systems control pH and have no oxidant demand outside of microbial
inactivation, 50 to 70 percent of the chlorine dioxide consumed will form chlorite. This puts an
effective limit on the dose that can be applied. Most systems will not be able to apply chlorine
dioxide doses of greater than 1.2 mg/L without risking exceeding the chlorite MCL. Systems
that cannot achieve the desired inactivation with a chlorine dioxide dose of less than 1.2 mg/L
may want to consider using another disinfectant in addition to chlorine dioxide to achieve the
necessary inactivation. Another possibility is that the chlorite could be reduced using a reductant
such as thiosulfate, which would then allow the use of higher chlorine dioxide doses.
Reduced Effectiveness at Low Temperatures
The disinfection effectiveness of chlorine dioxide is temperature sensitive. It is much
less effective at colder temperatures. Exhibit 5.5 shows the temperature sensitivity of chlorine
dioxide in terms of Cryptosporidium oocyst inactivation.
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5. Alternative Disinfection Strategies
Exhibit 5.5 Effect of Temperature on the CT Required for Cryptosporidium
Inactivation by Chlorine Dioxide
Temperature (°C) CT
log
(in mg-min/L) for 0.5-
inactivation (69.3%)
1 305
10 138
25 38
CT (in mg-min/L) for
2.0-log inactivation
1275
553
150
Source: USEPA2003a
As a result of this temperature dependence, systems in cold weather climates may not be
able to use chlorine dioxide to meet the Cryptosporidium inactivation requirements of the
LT2ESWTR.
Recommendations for Addressing this Issue
Systems may be able to achieve some inactivation by increasing the chlorine dioxide
dose and then using a reducing agent such as thiosulfate to reduce the chlorite to chloride, or by
using a second disinfectant. In general though, systems that regularly experience near freezing
temperatures should probably investigate other disinfection techniques.
Chlorine Dioxide MRDL
Chlorine dioxide itself can have health effects at elevated levels. Therefore it has an
MRDL of 0.8 mg/L. Systems using chlorine dioxide will have to monitor the chlorine dioxide
residual daily at the entry point to the distribution system, before the first customer. Systems
using chlorine dioxide may have to limit their doses to prevent exceeding the MRDL. If the
daily entry point sample exceeds the MRDL, systems are required by the Stage 1 D/DBPR to
monitor the chlorine dioxide residual in the distribution system.
Chlorite can react with excess chlorine in the distribution system to reform chlorine
dioxide. Some systems may opt to boost with chlorine to maintain a residual in the distribution
system. If doses are high enough, systems could exceed either the chlorine dioxide MRDL or the
chlorite MCL. Reformed chlorine dioxide can also volatilize at consumer's taps and react with
volatile organics to cause odor problems.
Systems that use chloramines for distribution residual may have difficulty measuring
chlorine dioxide because chloramines can interfere with its measurement.
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5. Alternative Disinfection Strategies
Recommendations for Addressing this Issue
If chlorine dioxide doses are kept below 1 mg/L, exceeding the MRDL should not be a
problem. If reformation of chlorine dioxide is not desired, chloramines can be used in the
distribution system instead of chlorine. If doses much higher than 1.2 mg/L are used, a reducing
agent can be added to the water before it enters the distribution system to reduce any chlorine
dioxide residual or chlorite to chloride. This will also prevent formation of chlorine dioxide in
the system by booster addition of chlorine.
If a system intentionally re-forms chlorine dioxide by boosting with chlorine in the
distribution system, the system should conduct bench scale tests to determine the correct chlorine
dose to add to achieve an adequate residual without exceeding either the chlorine dioxide MRDL
or the chlorite MCL. Systems should take into consideration the expected residence time in the
distribution system. Although some small systems in Canada have maintained adequate
residuals using doses of 0.4 to 0.6 mg/L of chlorine dioxide, other larger systems have found loss
of residual at the end of the distribution system using similar doses (Volk et al. 2002b).
If a system is using chloramines to maintain a distribution system residual, there are
amperometric titration techniques which can be used to determine between various chlorine
species. Systems should consult Standard Methods for the Examination of Water and
Wastewater (APHA, AWWA, and WEF 1998) for details of the method.
Can Form BrominatedDBPs
Chlorine dioxide can oxidize bromide ions to bromine. The bromine can then react with
organic matter to form brominated DBFs. Systems with high bromide concentrations that are
near the Stage 2 DBPR limits for TTHM or HAAS will need to take this into account.
Recommendations for Addressing this Issue
Systems with high bromide concentrations that are near the Stage 2 DBPR limits for
TTHM or HAAS can lower DBF formation by adding chlorine dioxide after the filters, where
organic concentrations are lower. Enhancing coagulation will also lower the amount of organic
matter available to react with chlorine dioxide after the filters. Systems that use chlorine dioxide
for pre-oxidation may be able to achieve some organic removal by using pre-sedimentation
basins. Systems with very high bromide can remove it using ion exchange columns, but this is
rarely an economical solution.
Degrades When Exposed to UV Light
Chlorine dioxide is sensitive to UV light and will degrade to form chlorate when exposed
to UV light. This will reduce chlorine dioxide residuals and therefore lower inactivation.
Recommendations for Addressing this Issue
Systems using chlorine dioxide can prevent degradation by light by covering the contact
basin. If a building or hard cover are not cost-effective or require too much space, floating
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5. Alternative Disinfection Strategies
covers can shield the chlorine dioxide from the UV light. The manufacturer should be consulted
in selecting the cover material to be sure it is compatible with chlorine dioxide.
Systems using chlorine dioxide and UV disinfection together should add the chlorine
dioxide either after the UV reactor or sufficiently ahead of the reactor that there is no residual
entering the reactor. Systems should not use the residence time of UV reactors to receive contact
time credit for chlorine dioxide added earlier in the treatment process.
Residual Dissipates Quickly
Chlorine dioxide is highly reactive and will react with GAC and anthracite in filters.
Chloride formed by the reaction of chlorine dioxide and GAC can also adsorb to the GAC and
cause weaker binding elements to be released. See Section 4.1 for more information on GAC
use. Chlorine dioxide is also volatile and can be lost in rapid mix basins or other unit processes
that have high turbulence and are exposed to the atmosphere.
Recommendations for Addressing this Issue
Filters should not be used to achieve contact time for chlorine dioxide. Rapid mix basins
can be used for contact time, but may require higher doses to achieve the same inactivation level.
Adding the chlorine dioxide after filtration will avoid any unnecessary residual loss and will
maximize the chlorine dioxide dose that is available for disinfection.
Systems adding chlorine dioxide as a pre-oxidant can add the chlorine dioxide in the
coagulation basins. Systems with low alkalinity may see a slight rise in pH after chlorine
dioxide addition.
Potential Formation of Odor-Causing Compounds
Chlorine dioxide residuals in customers tap water has been found to volatilize at the tap
and to react with volatile organic compounds (VOCs) in customer's houses forming compounds
with particularly bad kerosene-type odor (Hoehn et al. 1990). It can also sometimes give a
strong chlorinous odor.
Recommendations for Addressing this Issue
The appearance of odors in customer's homes is difficult to predict and therefore prevent.
Utilities can keep good customer complaint records and provide public education on what to do
if such odors occur. Suggestions for dealing with odors in the household include improving
ventilation and using carbon filters to remove the chlorine dioxide residual.
Additional Training Needed, Safety Concerns
The nature of chlorine dioxide and the chemicals used to generate it requires additional
training and safety precautions to ensure safe operation of the treatment plant. Sodium chlorite is
often used to generate chlorine dioxide. When acidified, it can produce large amounts of
gaseous chlorine dioxide. Chlorine dioxide at concentrations greater than 0.1 ppm is toxic and
can cause shortness of breath, coughing, respiratory distress, and pulmonary edema. Gaseous
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5. Alternative Disinfection Strategies
chlorine dioxide concentrations greater than 10 percent can be explosive. Sodium chlorite fires
burn very hot and produce oxygen as a byproduct.
Recommendations for Addressing this Issue
Systems should contact their chlorine dioxide equipment manufacturer to schedule any
necessary training. Sodium chlorite should be stored away from other chemicals, especially
acids and reducing agents. It should be stored in an area made of fire resistant materials such as
concrete. The area should be equipped with monitoring equipment to detect chlorine dioxide and
other chlorine components in the atmosphere. Proper ventilation and scrubbers should be
provided in the area. A special plan should be developed to respond to leaks or fires in the area
and the necessary equipment to implement the plan, including respirators, should be stored and
accessible outside the sodium chlorite storage area. If more than 1,000 pounds are stored on site
the plan must be formalized into a Risk Management Plan (RMP) and OSHA's specific
requirements for storage of chlorine dioxide must be satisfied.
5.4.3 Recommendations for Gathering More Information
Read Case Studies
Two case studies provided in Appendix B describe systems that switched to chlorine
dioxide to reduce DBFs in their finished water and the simultaneous compliance challenges they
encountered when making the switch.
Case Study #13 - Chlorine Dioxide for Primary Disinfection and Chloramines for
Secondary Disinfection on page B-75 describes a surface water treatment plant in a wholesale
system serving seven municipalities and approximately 92,000 people. The treatment plant
switched from chlorine to chlorine dioxide as its primary disinfectant and from chlorine to
chloramines for residual disinfection. In addition, the system uses chlorine dioxide intermittently
as a pre-oxidant in its raw water. Among the challenges the system has encountered is being
able to achieve sufficient Cryptosporidium inactivation to be granted LT2ESWTR credit and still
comply with the Stage 1 DBPR's chlorite MRDL.
Case Study #14 — Chlorine Dioxide for Primary Disinfection and Chloramines for
Secondary Disinfection on page B-81 describes a surface water system serving fewer than
10,000 people per day that also switched from chlorine to chlorine dioxide for CT and to
chloramines for residual disinfection. The system, which is challenged by zebra mussels
clogging its intake, found chlorine dioxide pretreatment works well as a replacement for the
potassium permanganate previously used. It also adopted a monitoring program to watch for
nitrification in its extensive distribution system.
See Additional References
Readers can turn to Chapter 7 for further references on this topic. Section 7.1.1 contains
general references on water treatment, section 7.1.2 contains references on controlling DBF
formation, and section 7.1.15 contains references on chlorine dioxide.
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5. Alternative Disinfection Strategies
Consider Additional Monitoring
The following are some suggestions for additional monitoring that may benefit water
systems using chlorine dioxide. The purpose of these monitoring suggestions is specifically to
address and prevent potential simultaneous compliance issues. Water system managers should
discuss process control monitoring with the manufacturer of their chlorine dioxide equipment or
their engineer.
^ If a system uses chlorine dioxide and has any kind of uncovered storage, chlorine
dioxide residuals should be measured after the open storage to ensure that a sufficient
chlorine dioxide residual has been maintained; and
S Customer complaints can be monitored to determine if chlorine dioxide residuals are
causing problems.
Consider Other Tools
In addition to water quality monitoring, there are additional tools available in Chapter 6
to help systems evaluate and improve their current water system in relation to the compliance
issues they may face when modifying their treatment operations. Examples of tools that can be
used when chlorine dioxide is used for Stage 2 DBPR compliance include:
• The "Guidance Manual for Monitoring Distribution System Water Quality"
(Kirmeyer et al. 2002) which can be used to assist water utilities in implementing a
distribution system water quality data collection and analysis program, especially for
chlorite and chlorine dioxide residuals;
• The AwwaRF report "Internal Corrosion of Water Distribution System" (AwwaRF
and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot
testing protocols that can be used to evaluate changes in corrosion potential due to the
switch to chlorine dioxide;
• The Standard Method 2350 (Oxidant Demand/Requirement) (APHA 1998) that
provides step-by-step instruction for the determination of chlorine dioxide demand;
• The AwwaRF report "Water Utility Self-Assessment for the Management of
Aesthetic Issues" (McGuire et al. 2004) which can be used to guide utilities in
conducting self-assessment on their taste and odor issues caused by ozonation and to
identify subsequent control strategies;
• The AwwaRF report "Tools and Methods to Effectively Measure Customer
Perceptions" (Colbourne 2001) which describes tools that allow utilities to measure
customer perceptions and changes in their opinions toward the use of chlorine
dioxide;
• Water/Wastewater Costs, Windows Version 3.0, (Wesner 2000) which provides
capital and O&M cost calculations for various water treatment processes based on
user inputted design parameters; and
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5. Alternative Disinfection Strategies
• EPA's Microbial Toolbox Guidance Manual (USEPA N.d.e) which describes
technologies which can be used for compliance with the LT2ESWTR. The manual
describes advantages and disadvantages for each technology and lists design and
operating considerations.
Readers are encouraged to read through Chapter 6 before making any final compliance decisions
5.5 Primary and Residual Disinfectant Use
Different combinations of primary and residual (i.e., secondary) disinfectants can present
different issues and concerns. For example, when ozone is used as the primary disinfectant
followed by chloramines as the residual disinfectant, water systems should be aware that
increased AOC concentrations resulting from ozonation may increase the likelihood of problems
with nitrification in the distribution system. On the other hand, the chlorite ion produced by
chlorine dioxide during primary disinfection may actually be effective at inactivating ammonia-
oxidizing bacteria and, as a result, reduce nitrification in the distribution system.
This section follows a different format than many of the previous sections in this
guidance manual. Exhibit 5.6 provides a summary table of the potential benefits and
simultaneous compliance issues of the various combinations of primary and residual
disinfectants. Brief paragraphs then follow the table, which describe noteworthy issues related to
different disinfectant combinations.
Some systems have used chlorine dioxide as a disinfectant residual. Monitoring
requirements, the MRDL for chlorine dioxide, the MCL for chlorite, and public notification
requirements (some violations are considered acute and require immediate notification) make
this a difficult option to implement to meet SWTR residual disinfection requirements. Thus,
chlorine dioxide is not included as a residual disinfectant option in Exhibit 5.6.
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5. Alternative Disinfection Strategies
Exhibit 5.6 Summary of Potential Benefits and Adverse Effects Associated with Different Combinations of
Primary and Residual Disinfectants
Disinfection Switch
(primary/residual,
from -4to)
Potential Benefits
Potential Adverse Effects
Drinking Water
Regulation(s)
Impacted
Chlorine/Chlorine ->
Chlorine/Chloramines
improved ability to maintain a
disinfectant residual
lower TTHM and HAAS
possible improved biofilm
control
improved taste and odor
excess ammonia can cause nitrification
possible elevated nitrite/nitrate levels
possible corrosion concerns
concerns for dialysis patients, fish owners, and
other industrial customers
Stage 2 DBPR
SWTR
TCR
LCR
Stage 1 DBPR
IESWTR
LT1ESWTR
Chlorine/Chlorine
Ozone/Chlorine
Lower TTHM and HAAS
Cryptosporidium inactivation
better taste and odor control
Bromate MCL concerns
additional bromate monitoring required
may increase brominated DBFs
increased AOC may enhance biofilm growth
Stage 2 DBPR
Stage 1 D/DBPR
LT2ESWTR
TCR
Chlorine/Chlorine H
Ozone/Chloramines
Lower TTHM and HAAS
Cryptosporidium inactivation
improved ability to maintain
disinfectant residual
may improve taste and odor
nitrification may increase
possible elevated nitrite/nitrate levels
possible corrosion concerns
bromate MCL concerns
additional bromate monitoring required
increased AOC may enhance biofilm growth
concerns for dialysis patients, fish owners, and
other industrial customers
Stage 2 DBPR
Stage 1 D/DBPR
SWTR
LT2ESWTR
TCR
LCR
Chlorine/Chloramines
-»
Chlorine Dioxide/
Chloramines
Lower TTHM and HAAS
Cryptosporidium inactivation
Giardia and virus inactivation
can control iron and manganese
chlorite from chlorine dioxide
may control nitrification
additional chlorine dioxide and chlorite
monitoring required
chlorite MCL concerns
chlorine dioxide MRDL concerns
Stage 2 DBPR
Stage 1 DBPR
LT2ESWTR
LCR
Chlorine/Chloramines
-»
Ozone/Chloramines
Lower TTHM and HAAS
Cryptosporidium inactivation
improved taste and odor control
Giardia and virus inactivation
increased AOC can encourage nitrification and
biofilm growth
additional bromate monitoring required
ozone taste and odor issues
may create brominated DBFs
bromate MCL concerns
Stage 2 DBPR
Stage 1 D/DBPR
LT2ESWTR
TCR
LCR
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5. Alternative Disinfection Strategies
Ozone/Chlorine^
Ozone/Chloramines
Chlorine/Chlorine or
Chlorine/Chloramines
-4 UV/Chlorine or
UV/Chloramines
Ozone/ Chlorine ->
Ozone/ UV/Chlorine
• Lower TTHM and HAAS
• improved ability to maintain a
disinfectant residual
improved taste and odor control
Giardia and virus inactivation
• Lower TTHM and HAAS
• Cryptosporidium inactivation
• Giardia and virus inactivation
•
• additional Cryptosporidium
inactivation
good taste and odor control
• Giardia and virus inactivation
AOC may encourage nitrification
• concerns for dialysis patients, fish owners, and
other industrial customers
• possible corrosion concerns
• UV less effective than chlorine at inactivating
viruses
UV is not a pre-oxidant
• less taste and odor control
• ozone can lower UV transmittance
• Stage 2 DBPR
• SWTR
• TCR
• LCR
• Stage 2 DBPR
• SWTR
• LT2ESWTR
• LT2ESWTR
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5.5.1 Noteworthy Issues About Disinfectant Combinations
Potential Drawback of Switching from Chlorine/ Chloramines to Ozone/ Chlor amines
Changing to ozone as a primary disinfectant while maintaining chloramines as a
secondary disinfectant may impact TCR compliance due to the reaction of ozone with natural
organic matter to form AOC. Having already established distribution system practices for
biofilm growth in chloraminated distribution water, public water systems making this
disinfection practice modification should focus on the biological stability of their distribution
system water.
In cases where the use of ozone as the primary disinfectant increases levels of AOC,
biological stability in the distribution system could be disrupted. AOC provides nutrient value
for cell metabolism. In a previously chloraminated system, control of nitrification may be
achieved using one or more of the techniques described in Section 5.1.2. However, the
additional nutrition provided by the increased AOC may require modification to the practices.
Alternatively, biological filtration can be used to effectively reduce nutrient levels. Biological
filtration can also reduce dissolved oxygen, which can lead to changes in redox chemistry in the
system and potentially change scale chemistry, affecting corrosion control treatment.
Potential Benefit of Switching from Chlorine/ Chloramines or Ozone/ Chloramines to Chlorine
Dioxide/ Chloramines
McGuire et al. (2006) provided field and laboratory evidence that the chlorite ion may be
effective at controlling nitrification in distribution systems. The study showed that even low
dosages of chlorite (0.1 mg/L) were effective at inactivating 3 to 4 logs of ammonia-oxidizing
bacteria over several hours. Field investigations at five water systems in Texas showed that the
presence of chlorite in the distribution systems resulted in less loss of chloramines and ammonia-
nitrogen.
5.5.2 Recommendations for Gathering More Information
Read Case Studies
Case Study #13 - Chlorine Dioxide for Primary Disinfection and Chloramines for
Secondary Disinfection on page B-75 describes a surface water treatment plant in a wholesale
system serving seven municipalities and approximately 92,000 people. The treatment plant
switched from chlorine to chlorine dioxide as its primary disinfectant and from chlorine to
chloramines for residual disinfection. In addition, the system uses chlorine dioxide intermittently
as a pre-oxidant in its raw water. Among the challenges the system has encountered is being
able to achieve sufficient Cryptosporidium inactivation to be granted LT2ESWTR credit and still
comply with the Stage 1 DBPR's chlorite MRDL.
Case Study #14 - Chlorine Dioxide for Primary Disinfection and Chloramines
for Residual Disinfection on page B-81 in Appendix B provides an example of a small surface
water system that switched from chlorine for primary and residual disinfection to chlorine
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dioxide for primary disinfection and chloramines for residual disinfection. The system pays
close attention to the potential for nitrification in its distribution system as a result of the
chloramines, and has developed a monitoring program and guidelines for action to prevent
nitrification episodes. Chlorite is one of the parameters tracked closely in the distribution
system. The system tries to take advantage of the possibility that chlorite may be toxic to
nitrifying bacteria.
See Additional References
Readers can refer to Chapter 7 for more references on this topic. Section 7.1.1 contains
references on general water treatment, section 7.1.2 contains references on controlling DBF
formation, Section 7.1.12 contains references on chloramines, Section 7.1.13 contains references
on ozone, Section 7.1.14 contains references on UV disinfection, and Section 7.1.15 contain
references on chlorine dioxide.
Consider Tools
There are additional tools available to help systems evaluate and improve their current
water system in relation to the compliance issues they may face when modifying their treatment
operations. Readers are encouraged to read through Chapter 6 before making any final
compliance decision.
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6 Making Compliance Decisions
This Chapter covers:
6.1 Introduction
6.2 Issues to Consider When Making a Compliance Decision
6.3 Tools for Gathering Information
6.4 Basic Approach for Implementing Regulatory Compliance Projects
The information provided in this chapter is meant to help water system managers and
their regulators identify what issues should be considered before a change in treatment or
operations is made. It also describes tools available to help systems collect information and a
methodology for using information generated by these tools to make a compliance decision.
6.1 Introduction
To comply with the Stage 2 DBPR and LT2ESWTR, water systems will be making
changes to their treatment and operations ranging from relatively small adjustments in how they
run existing systems to major capital improvements. Systems should weigh the impacts of any
modifications they are considering, including impacts related to the issues described in Chapter 2
and Section 6.2. They should identify what information they need to help them decide whether
and how they can adjust their treatment to comply. If they do not have that information, they
should identify what monitoring and/or studies are necessary to obtain it. Subsection 6.3.1
provides resources system managers can use as guidance for collecting data about their systems
to help them make these decisions.
Subsection 6.3.3 describes available desktop studies that can be useful tools for decision-
making. Subsection 6.3.4 lists resources available about bench-scale tests, including those
describing proper jar testing applications and procedures. These are all relatively inexpensive
ways for a system to determine whether it can comply by optimizing its existing treatment.
If a system opts to install new treatment, managers should proceed carefully and in an
informed way. They too should consider the issues described in Chapter 2 and Section 6.2 and
how those issues affect what treatment should be installed.
Some water systems will have more resources available than others for evaluating the
potential impacts of a treatment change. The references provided in Section 6.3 give readers
perspective on how involved and expensive different evaluation tools can be. Water system
managers, particularly those with limited resources, are encouraged to take the time to make
informed decisions about what evaluations should be performed before new treatment is
installed.
Water system managers should examine the issues listed in Section 6.2 and determine
which are most important to their system. Failing to consider the appropriate issues can cause
unforeseen problems. For example, a system with historic low levels of arsenic in their water
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6. Making Compliance Decisions
may decide to switch from chlorine to chloramines based on factors such as cost, compatibility
with the existing process, and operator knowledge of the process; however, the change in
oxidation reduction potential in the distribution system may cause arsenic adsorbed in
distribution system scale to be released. In making determinations, it is important not only to
evaluate the number of positives or negatives for a given compliance response but also to
analyze the magnitude of each advantage or disadvantage.
Finally, simultaneous compliance is a necessary consideration when deciding how to
proceed. System managers should use the information and references available throughout this
and other guidance manuals to make Stage 2 DBPR and LT2ESWTR compliance decisions with
confidence that all regulations will be met.
6.2 Issues to Consider When Making a Compliance Decision
As the previous chapters have indicated, numerous considerations should be taken into
account when deciding on the best strategy for complying with a new regulation. Factors should
be considered and balanced when coming to a conclusion that will satisfy all parties: system
owners; regulatory agencies; customers; and other stakeholders. The earlier sections of this
manual have laid out considerations for specific technologies. This section identifies issues to
consider whenever any change is made to a water system, including changes that may not be
discussed previously, such as novel technologies or seemingly minor operational changes.
Exhibit 6.1 summarizes the types of considerations that should be made before making
changes, along with some direction as to what kind of information would help decision-makers
during their review of those considerations.
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Exhibit 6.1 Issues to Consider When Deciding How to Comply with Stage 2 DBPR and/or LT2ESWTR
Issue
Description of the Issue
Information to Help Systems Assess
the Issue
Production Capability
Quantity and quality of water may be an issue in arid or highly
developed areas.
Systems operating at or near peak production capabilities are
likely to be affected by decreases in production.
Some treatment technologies (e.g., enhanced filtration and
anion exchange, membrane technologies) may lower
production capacity.
Methods of lowering disinfection byproduct (DBF) production
(e.g., changing storage tank fill/drain cycles, removing storage
tanks) can affect the amount of storage available for droughts
and fire fighting.
Chapter 4 discusses issues with treatment
technologies in more detail.
The amount of storage needed for uses such as
droughts and fire fighting should be taken into
account when making changes to distribution
system storage. Hydraulic models as described in
Section 6.3.2 can aid in making these
determinations.
Compatibility with
Existing Treatment
Facilities
A public water system (PWS) is a series of linked and inter-
related processes that affect one another. Systems should
consider the effects that changes or additions to any process in
the system may have on other processes within the system.
Any modification that changes the chemical properties of the
water such as pH, alkalinity, metals concentrations, or organic
matter concentration will likely affect the coagulation and
sedimentation process.
Adding new chemicals may cause corrosion of plant materials.
Case studies #1-5, #7, and #9-14 in Appendix B
provide examples of systems that faced issues as
a result of changing existing treatment processes.
Many known effects of technologies are discussed
in the preceding chapters. Other effects may be
specific to a particular water quality or other site-
specific variables, or to a technology not
discussed in this guidance manual.
Tools discussed in Section 6.3 (e.g., bench
studies, pilot testing) are important for
determining potential effects of system changes.
Production of Residuals
and Disposal Issues
Some process changes can affect the composition or cause the
production of residuals or other wastes. Disposal of additional
waste should be taken into account when determining costs and
in other considerations.
Systems should consider whether waste streams can be
disposed of through sanitary sewer lines or if separate disposal
means are required. Pretreatment requirements and
requirements by the wastewater treatment plant should be
investigated if sewer disposal is an option.
Process changes and changes in water quality (e.g., pH,
alkalinity, metals concentrations, and organic matter) may
affect the properties of residuals (e.g., the residual's density
and its ability to be dewatered).
Sections 3.6.2 and 3.7.2 provide more information
on disposal of additional waste.
Combinations of jar tests and pilot tests can help
determine changes that might occur and how best
to deal with them, as described in sections 6.3.4
and 6.3.5, respectively.
Case studies #3 and #6 in Appendix B provide
examples of residuals disposal issues.
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Exhibit 6.1 Issues to Consider When Deciding How to Comply with Stage 2 DBPR and/or LT2ESWTR
Issue
Description of the Issue
Information to Help Systems Assess
the Issue
Site-Specific Issues
System size and available resources vary widely and can impact
compliance strategies.
Systems need to consider the number and skill of operators
when making treatment decisions.
Systems need sufficient space for new technologies to be easily
accessed for service and maintenance.
A system should consider how the addition of any new
processes will affect the hydraulic gradient in the plant.
Location can be an important factor (e.g., price and availability
of chemicals, delivery charges for equipment and chemicals,
effect of the local climate on treatment processes).
System-specific studies are critical to determining
how various issues will affect a system. Some
issues can be sufficiently answered through
literature reviews and discussions with
manufacturer representatives. Others will need to
be investigated more thoroughly using the
techniques discussed in Section 6.3.
The case studies in Appendix B illustrate how
system-specific issues affect compliance
decision-making.
Compatibility with
Distribution System
Materials
Changes to water quality, especially to pH, alkalinity, or redox
potential, can affect corrosion both in the plant and in the
distribution system.
Some types of distribution system surfaces (e.g., highly scaled
iron pipes) lend themselves to easily releasing scale materials
into the water if changes are made to water quality.
Any treatment change should be analyzed to determine if it will
change the corrosion rate of system materials.
Section 6.3 discusses desktop studies along with
bench and pilot methods such as pipe loop
studies, which can be used to determine changes
in corrosion rates associated with a given change.
Section 6.3.1 discusses water quality monitoring,
which can provide warning if corrosion rates do
change unexpectedly after a treatment
modification.
Case studies #2 and #5 in Appendix B provide
relevant examples.
Appendix D also includes evaluation tools that
can be used to determine changes in corrosion
rates.
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Exhibit 6.1 Issues to Consider When Deciding How to Comply with Stage 2 DBPR and/or LT2ESWTR
Issue
Description of the Issue
Information to Help Systems Assess
the Issue
Compatibility with
Distribution System
Operations
Treatment changes that alter the chemical make-up of the water
can affect the distribution system and may require changes in
its operation.
Systems should consider corrosion issues and microbial
stability of the system (some chemicals added to the water may
promote microbial growth in the distribution system). Systems
using chloramines may have an increased risk of nitrification
problems.
Systems may need to make distribution system changes (e.g.,
more frequent flushing, reducing residence times) to counter
increased microbial activity.
Section 5.1.2 describes the nitrification problem
with chloramines.
Section 6.3 describes models that can help to
predict and circumvent problems such as
nitrification.
Case studies #1, 2, 5, 9, 10, 13, and 14 discuss
distribution system issues that were raised as a
result of treatment changes.
Environmental Issues
Changes to treatment or system operations may present
environmental issues (e.g., change to flushing procedures to
remove chloramines, which are toxic to fish, before water is
discharged to natural waters).
Constituents added to drinking water may raise issues at the
wastewater treatment plant (WWTP) (e.g., metals such as zinc,
used in some corrosion inhibitors, may inhibit the
denitrification process at the WWTP) because some treated
water eventually ends up in the sewer system. WWTPs may
also have discharge permit limits for water quality parameters
like pH, metals, and phosphorus.
If a system needs to purchase new land for a treatment process
or wants to change sources, environmental issues may arise
such as the presence of wetlands or endangered species;
discharges to a stream or surface water body (e.g. filter
backwash water, well development water)
Systems should review environmental regulations
and WWTP requirements before making any
major changes. Related environmental
regulations may include SDWA Source Water
Assessment Program and Wellhead Protection
Program (State primacy agency); state regulations
on wetland protection and river protection; and
local zoning ordinances.
Case study #6 in Appendix B addresses a possible
radiation exposure issue for workers handling
radioactive water treatment residuals.
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Exhibit 6.1 Issues to Consider When Deciding How to Comply with Stage 2 DBPR and/or LT2ESWTR
Issue
Description of the Issue
Information to Help Systems Assess
the Issue
Consumer Driven Issues
Changes may result in consumer complaints about tastes, odors,
or colored water, which can arise from many different factors.
Changes in water chemistry can cause corrosion, causing
colored water at the tap. Tastes and odors can result from high
disinfectant doses or from microbial activity encouraged by
water chemistry changes.
Changes in water rates require good communication
Good public education is important for public health protection
and can head off consumer complaints.
• Section 5.1.2 discusses issues customers need to
understand about use of chloramines.
• Sections 6.3.4 and 6.3.5 describe bench-scale and
pilot testing which help predict if changes will
cause undesired outcomes at the consumer's tap.
• Section 6.3.8 provides some resources for
planning, such as public education efforts.
• Case studies #5, 8, 11, and 14 in Appendix B
discuss relevant examples.
Preference of Operations
Staff
• Operator preferences for selecting a compliance option may be
based on manpower and training requirements, safety concerns,
monitoring requirements, chemical feed methods, the amount
of automation, and equipment positioning.
• Systems should solicit input from operations staff,
since they are responsible for the day-to-day
implementation of any changes, can raise valid
concerns that others have not considered during
the planning process, and understand the
implications for training.
• Case studies #10-12 in Appendix B discuss the
operational needs and implementation issues with
UV treatment.
Consecutive System
Requirements
Systems selling some or all of their water to other systems will
have to take into account the needs of the purchasing systems,
which may not have treatment themselves.
Consecutive (purchasing) systems may have large distribution
systems with long residence times. Water that is delivered may
meet total trihalomethane (TTHM) maximum contaminant
levels (MCLs) at delivery but may exceed them nearer the end
of the distribution system.
Mixing different types of disinfectant residuals can cause
problems if not done very carefully.
• EPA's Consecutive Systems Guidance Manual for
the Stage 2 DBPR (USEPA N.d.b) will provide
helpful information that guides decision-making
for consecutive systems.
Cost
• Cost can be a driving force behind selection of compliance
strategies
Section 6.3.7 describes several computer models
that can help with costing various technologies.
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6.3 Tools for Gathering Information
The objective of this section is to provide examples of tools that can assist utilities to
evaluate and improve their current water system in relation to compliance with Total Coliform
Rule (TCR), Lead and Copper Rule (LCR), LT2ESWTR, and Stage 2 DBPR. These tools
include computer software, models, technical publications, and research reports that can be
acquired through public domains, non-profit organizations, or private companies. While some of
the tools can be obtained freely from government agencies or the internet (such as reports and
guidance manuals from EPA), the acquisition of some tools may either require member
subscription (such as reports from AwwaRF) and/or fees (such as AWWA publications and
proprietary software).
These tools are organized into the following eight categories:
• Water quality monitoring
• Hydraulic and water quality modeling for distribution systems
• Desktop evaluations
• Bench-scale testing
• Pilot testing
• Full-scale applications
• Cost estimation
• Community preferences
A subsection is dedicated to each of these categories and a brief introduction is included to
describe the purpose of tools in that category and how they relate to other subsections.
This document does not intend to provide a comprehensive list of tools that may be used
to assist with simultaneous compliance, but rather to provide examples of available tools.
Readers of this document should consult with regulatory agencies and professional organizations
for other similar tools and updated information.
6.3.1 Water Quality Monitoring
Tools included in this section provide guidance and methodologies for monitoring water
quality in water supplies, water treatment facilities, and transmission and distribution systems.
The first five tools are EPA documents that describe water quality sampling requirements for
various regulations. Utilities should consult with these documents to meet the minimum
regulatory monitoring requirements.
• Total Coliform Rule: A Quick Reference Guide (USEPA 2001f). This EPA
document provides updated information on water quality monitoring requirements for
the TCR. This document is included in Appendix A and can also be obtained from
the following EPA Web site:
http://www.epa.gov/safewater/disinfection/tcr/pdfs/qrg tcr vlO.pdf
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• A Small System Guide to the Total Coliform Rule (USEPA 2001g). This EPA
document provides guidance on monitoring requirements for small systems that serve
3,300 or fewer people. This document can be obtained from the following EPA Web
site: http://www.epa.gov/safewater/smallsys/small-tcr.pdf.
• Drinking Water Regulations: National Primary Drinking Water Regulations for
Lead and Copper Rule (USEPA 2000b) & Lead and Copper Rule Minor
Revision Fact Sheet (USEPA 1999i). Lead and Copper Rule: A Quick Reference
Guide (USEPA 2004g). These documents summarize the monitoring requirement of
the LCR and can be found on the following EPA web site:
http://www.epa.gov/safewater/lcrmr/index.html . The LCR quick reference guide is
also included in Appendix A. In addition, EPA proposed minor revisions to the LCR
in 2006 that affect monitoring requirements. The proposed changes are summarized
in a fact sheet available at the EPA Web site listed above.
• Source Water Monitoring Guidance Manual for Public Water Systems (USEPA
2006f). This EPA guidance manual for PWSs affected by the rule provides
information on laboratory contracting, sample collection procedures and data
evaluation, and interpretation. This guidance manual also provides information on
grandfathering requirements for Cryptosporidium and E. coll data under the
LT2ESWTR. The guidance manual is available at the following EPA web site:
http://www.epa.gov/safewater/disinfection/lt2/pdfs/guide It2 swmonitoringguidance.
p_df
• The Stage 2 DBPR Initial Distribution System Evaluation Guidance Manual
(USEPA 2006a). This EPA document provides distribution system water quality
monitoring requirements for the Stage 2 DBPR. This guidance manual describes the
monitoring frequency, number of sampling locations, and the methodologies for
selecting appropriate sampling locations for TTHM and HAAS. The guidance
manual is available at the following EPA web site:
http://www.epa.gov/safewater/disinfection/stage2/compliance idse.html
• Initial Distribution System Evaluation Guide for Systems Serving < 10,000
People (USEPA 2006g). This EPA document provides distribution system water
quality monitoring requirements for the Stage 2 DBPR for small systems. This
guidance manual describes the monitoring frequency, number of sampling locations,
and the methodologies for selecting appropriate sampling locations for TTHM and
HAAS. It is available at the following web site:
http://www.epa.gov/safewater/disinfection/stage2/compliance_idse.html.
• Design of Early Warning and Predictive Source-Water Monitoring Systems
(AwwaRF Report 90878, Grayman, Deininger and Males 2001). This research
report provides guidance on the development of early warning systems for real-time
source water contaminant monitoring. These systems will allow utilities to predict
water quality events in the source water that may require subsequent treatment
adjustment in the water treatment facilities.
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• Guidance Manual for Monitoring Distribution System Water Quality (AwwaRF
Report 90882, Kirmeyer et al. 2002). This document provides water utilities with
guidance on how to design and implement a distribution system water quality data
collection and analysis program. This document features a comprehensive approach
for collecting and analyzing water quality information, providing important input to
costly infrastructure improvements, documenting benefits of operational procedures,
and addressing consumer complaints.
• Methods for Real-Time Measurement of THMs and HAAs in Distribution
Systems (AwwaRF Report 91003F, Emmert et al. 2004). This document
summarizes existing technologies and methods that can be used to quantify
concentrations of total THMs and the sum of the five regulated HAAS in near-real
time. Some of the methods are also capable of quantifying individual THM and HAA
species.
• Optimizing Corrosion Control in Water Distribution Systems (AwwaRF Report
90983, Duranceau, Townley and Bell 2004). This report demonstrates the use of a
multi-element sensor electrochemical technique for instantaneously monitoring
corrosion and optimizing corrosion control in water distribution systems. This
document also describes the uses of real-time corrosion sensors to screen various
corrosion inhibitors.
• You may go to the following documents for national occurrence information to
determine how your source water compares with source waters of other systems, and
to get a sense of the technologies being commonly used by water systems with source
water quality similar to yours.
- USEPA. 2005e. Stage 2 Occurrence Assessment for Disinfectants and
Disinfection Byproducts. EPA 815-R-05-011
- USEPA. 2005a. Occurrence Assessment for the Final Stage 2 Disinfectants and
Disinfection Byproducts Rule. Prepared by The Cadmus Group, Inc. Contract 68-
C-99-206. EPA 815-R-06-002.
- McGuire, M.J., J.L. McLain, and A. Obolensky. 2002. Information Collection
Rule Data Analysis. AwwaRF Report 90947. Project #2799. Denver: AwwaRF.
6.3.2 Hydraulic and Water Quality Modeling for Distribution System
While documents listed in the previous section provide guidance on monitoring water
quality, tools described in this section provide means to predict and model water quality changes
in the distribution system based on the calculation of hydraulic retention time (water age),
kinetics of water chemistry, and parameters that could affect water chemistry (e.g., temperature,
pipe material, etc.). In addition to water quality modeling, most of these tools are also capable of
hydraulic modeling. Results from these modeling exercises can assist utilities in projecting
distribution system water quality and planning for simultaneous compliance.
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• EPANET (USEPA 2002b). Developed by EPA, EPANET 2.0 is a Windows-based
computer program that performs extended period simulation of hydraulic and water
quality behavior within pressurized pipe networks. It is available at the following
EPA Web site: http://www.epa.gov/ORD/NRMRL/wswrd/epanet.html. Several
software companies (including DHI, MWH Soft, Haestad Methods, and Wallingford
Software) use EPANET as the foundation to develop their proprietary versions of
hydraulic and water quality modeling tools. These commercial programs provide
similar functions to that by EPANET, but may be more flexible, and user-friendly.
• SynerGEE® Water. Developed by Advantica, SynerGEE Water is a simulation
software package for modeling and analyzing water distribution systems. It is
capable of conducting steady state analysis, dynamic analysis, and the analyses of
water age, source contribution, water quality, fire flow, and pump operating costs.
• Advanced Water Distribution Modeling and Management (Walski et al. 2003).
Written by industry experts, it provides practical resources for engineers and
modelers. Walks through the modeling process from start to finish - from data
collection and field-testing to using a model for system design and complex
operational tasks. Explores transient analysis, GIS technology applications, and
water system vulnerability and security.
• Water Quality Modeling of Distribution System Storage Facilities (AwwaRF
Report 90774, Grayman et al. 2000). This document describes procedures that can
be used to characterize water quality conditions and changes in water storage
reservoirs. This report also provides a hydraulic model with a water quality model
that can be used to determine the effects of daily fill and draw cycles. Optimum
design and operation of distribution system tanks and reservoirs is also addressed.
• Predictive Models for Water Quality in Distribution Systems (AwwaRF Report
91023F, Clement et al. 2005). This research report provides a comprehensive
review of the current state of predictive water quality modeling covering water
quality processes models for corrosion and metal release, discoloration, disinfectant
decay, DBFs, and microbial water quality. This review also describes how these
models can be applied to distribution networks, including water quality network
models, storage tank models, and zone level models.
• Computer Modeling of Water Distribution Systems Second Edition (AWWA
Manual M32) (AWWA 2004a). This manual provides step-by-step instructions for
the design and use of computer modeling for water distribution systems. Distribution
system operators can build an accurate and detailed "virtual" model of the system
using computer software. Computer models can help the operators to uncover
problems and explore different scenarios to solve the problems without actually
entering or changing the physical distribution system. This manual also includes
results from a survey of U.S. and Canadian water utilities on future trends of water
distribution and water quality modeling.
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6.3.3 Desktop Evaluations
Desktop evaluation tools included in this section can be used to assist utilities in
evaluating and optimizing treatment strategies to comply with LT2ESWTR and Stage 2 DBPR.
These tools are particularly helpful in identifying the best combination of treatment components
for simultaneous regulatory compliance.
• Water Treatment Plant Model for MS Windows 3.1: Version 1.55 (USEPA
1994b). The Water Treatment Plant Model (WTP) was originally developed in support
of the Stage 1 Disinfectant/Disinfection Byproducts Rule. It was prepared with the
understanding that the predictions should reflect the central tendency for treatment. It
is not to be construed that the results from the model will necessarily be applicable to
individual raw water quality and treatment effects at unique municipalities. The
model does not replace sound engineering judgment based on site-specific treatability
data to evaluate the best manner in which to address the requirements of the SWTR or
D/DBP rules.
Originally developed by EPA in 1992 to support the Stage 1 D/DBP Rule, the Water
Treatment Plant Model was updated in 1994 to include more data and alternative
treatment processes to assist utilities in achieving total system optimization (TSO),
i.e., a method by which treatment processes can be implemented such that a utility
meets the required levels of disinfection while maintaining compliance with
requirements of Stage 1 and, potentially, Stage 2 DBPR. Available on EPA's website:
http://vosemite.epa.gov/water/owrccatalog.nsf/e673c95bll602f2385256ael007279fe/
80acea46c3412all85256b06007259ee!OpenDocument The model was further
updated in 1999 to include new data and to update treatment processes. The latest
version of the model (USEPA 200 li) is available by calling 1-800-426-4791.
• Operational Evaluation Guidance Manual (USEPA N.d.f). The purpose of this
guidance manual is to provide technical information and guidance for water systems
and states to use for identifying and reducing significant excursions of DBF levels.
• Self-Assessment for Treatment Plant Optimization, International Edition.
(Lauer 2001). Optimize conventional treatment processes without investing in major
capital improvements with this detailed guidebook. The guide provides procedures
for optimizing particulate removal and disinfection through improvements in
administration, maintenance, design, and operations.
• Partnership for Safe Water Information Center. The Partnership for Safe Water
is a voluntary program organized collaboratively among EPA, AWWA, and other
drinking water organizations to optimize water treatment plant performance above
and beyond regulatory requirements. The Information Center, found at the following
Web site, http://www.awwa.org/science/partnership/InfoCenter/, includes self-
assessment checklists, sample reports, and fact sheets to help a water system get
started.
• The Rothberg, Tamburini & Winsor Blending Application Package 4.0 (AWWA
200 la). This new RTW program is the successor of Model for Water Process and
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Corrosion Chemistry 4.0. This computer program is developed to simplify the task of
evaluating water chemistry associated with precipitation/coagulation and corrosion
potential of water. The model provides prediction on the change of water quality
(such as pH, hardness, alkalinity, and Langelier Saturation Index) in response to the
changes in operating conditions. The new version can handle more than one water
source under multiple blending scenarios. Although the RTW model adequately
predicts the changes in water quality, any intent of correlating these information to
actual corrosion potential should also include more detail and direct corrosion
assessment as described in other sections of this document.
• Metals Solubility Prediction Tools. Additional models have been developed to
evaluate the solubility of metals in the distribution system. The AwwaRF report, A
General Framework for Corrosion Control Based on Utility Experience and Control
ofPb and Cu Corrosion By-Products Using CORRODE Software. (Edwards and
Reiber 1997a, b) includes chemical equilibrium software that can be used to identify
causes of corrosion problems and test the validity of different corrosion control
strategies. The USGS PHREEQC is a computer program designed to perform a wide
variety of low-temperature aqueous geochemical calculations. Information on
PHREEQC is available on the USGS website at
http://wwwbrr. cr. usss.sov/proiects/GWC coupled/phreeqc/
6.3.4 Bench-Scale Testing
This section includes bench-scale testing procedures and methods for acquiring technical
information on water quality, treatment efficacy, and internal corrosion potential. This
information is critical to water quality modeling and system evaluation and optimization. Five
categories of bench-scale testing methods are presented in this section, including:
• Disinfectant Demand and Decay
• DBF Growth and Decay
• Taste and Odor Profiles
• Jar/Column Testing Procedures
• Internal Corrosion Assessment
Each of these bench-scale testing tools is described below.
Disinfectant Demand and Decay
• Standard Method 2350, Oxidant Demand/Requirement (American Public Heath
Association (APHA), AWWA, and Water Environment Federation (WEF)
1998). Information on chlorine demand in the transmission and distribution system is
critical to the assurance of public health as well as an effective internal control
practice. Increasing chlorine dosage to compensate excessive chlorine demand may
also result in high DBF formation. This standard method provides step-by-step
instruction on four methods for the determination of oxidant demands: one method
each for chlorine and chlorine dioxide and two methods for ozone (batch and semi-
batch methods).
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DBF Formation and Decay
• Field and material-specific simulated distribution system testing as aids to
understanding trihalomethane formation in distribution systems (Brereton and
Mavinic 2002). This paper presents results from a comprehensive study using an
extensive field monitoring program and an improved simulated distribution system
(SDS) bench-scale test. The SDS bench test includes the potential increased chlorine
demand caused by internal pipe walls in the evaluation of DBF formation. During
field testing, this study compared both pre-formed THM and THM formation
potential among several distribution system locations to reduce inherent uncertainties
associated with the complexities of network hydraulics, leaving exposure to the
internal pipe environment as the primary factor of interest. Findings in this paper
suggest the reliability of using the material-specific SDS (MS-SDS) test is a better
representation of DBF evolution in a real distribution system. The MS-SDS test is
readily adaptable for pilot-plant studies where real distribution system conditions are
inaccessible. This article can be acquired from the following internet Web site:
http://pubs. nrc-cnrc. gc. ca/cgi-bin/rp/rp2 abst e ?dee 101-0 74 29 nsnf cjce.
• Simulated Distribution System DBF development procedure
- Predicting the formation of DBFs by the simulated distribution system (Koch et
al. 1991). This study developed a simulated distribution system (SDS) method
that can be used to predict the amounts of DBFs that would form in a distribution
system. Key parameters (including chlorine dosage, incubation temperature, and
incubation holding time) are chosen to simulate the conditions of the treatment
plant and the distribution. Results from this study show good correlation between
the SDS samples and the samples collected from the distribution systems.
- Assessing DBF yield: uniform formation conditions (Summers et al. 1996). This
paper presents a new chlorination approach, the uniform formation conditions
(UFC) test. The UFC test can be used to assess disinfection DBF formation under
constant, yet representative conditions. Results from this study suggest that UFC
test can be used for a direct comparison of DBF formation among different waters
and allows the evaluation of how treatment changes affect DBF formation in a
specific water.
Taste and Odor Profiles
• Practical Taste-and-Odor Methods for Routine Operations: Decision Tree
(AwwaRF Report 91019, Burlingame et al. 2004). This report describes the
existing and newly developed sensory methods for monitoring the taste-and-odor
quality of drinking water, as well as the odor quality of source or partially-treated
water, in order to understand the reasons for customers' attitudes and complaints, to
make decisions for treatment, to track problems to their sources, and to provide early
warning of problems that are expected to recur. The new methods are described in
detail in this report while existing methods are already described in Standard Methods
for the Examination of Water and Wastewater (APHA 1998). The new methods
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6. Making Compliance Decisions
provide early warning to geosmin and 2-MIB, information about treatment,
information for the approval of new installations in distribution, and the confirmation
of customer complaints.
• Water Utility Self-Assessment for the Management of Aesthetic Issues (AwwaRF
Report 90978F, McGuire et al. 2004). This report provides guidance for utility to
conduct self-assessment on its T&O control strategies. This self-assessment tool
improves a utility's ability to quickly identify the source of problems, implement
control strategies, and communicate with its stakeholders.
Jar/Column Testing Procedures
• Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual,
Section 3: The Step 2 Procedure and Jar Testing (USEPA 1999h). This document
provides procedures for conducting jar testing to determine the optimum coagulation
conditions for achieving desirable total organic carbon (TOC) removal and
coagulated/settled water turbidity. This document can be found at the following EPA
Web site: http://www.epa.gov/safewater/mdbp/coagmde.pdf.
• Procedures Manual for Polymer Selection in Water Treatment Plants (AwwaRF
Report 90553, Dentel et al. 1989). This manual describes the bench-scale testing
protocols for the selection of coagulants as well as the appropriate types of polymer
for coagulant aids, filter aids, and sludge dewatering aids.
• Operational Control of Coagulation and Filtration Processes (AWWA Manual
M37, AWWA 2000). This manual provides information on standard jar testing
procedure for bench-scale coagulation testing.
• Enhanced and Optimized Coagulation for Particulate and Microbial Removal
(AwwaRF Project #155, Bell et al. 2001). This research project evaluated the effect
of enhanced and optimized coagulation on particulate and microbial removal. This
study demonstrates the use of bench-scale studies on 18 waters corresponding to the
EPA TOC - alkalinity matrix and removal of protozoan cysts and oocysts, viruses,
enteric bacteria, spores, and bactedophage. The bench-scale jar testing protocol
described in this report can be used to determine the optimum coagulant type,
coagulant dose, and coagulation pH for the compliance of Stage 2 DBPR, as well as
LT2ESWTR and TCR.
• Design of Rapid Small-Scale Adsorption Test for a Constant Diffusivity
(Crittenden et al. 1986) This paper describes the fundamental theory and bench
scale testing procedure for using a small adsorptive media column to quickly predict
effective GAC adsorption capacity for specific organic compounds in full-scale
operation. This technique, known as RSSCT, has been widely accepted by the
chemical engineering industry and has also been used to estimate useful GAC life
time when used for the removal of aquatic organic contaminants.
• Prediction of GAC Performance Using Rapid-Small Scale Column Tests
(AwwaRF Project #230, Crittendon 1989). This document describes the use of
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6. Making Compliance Decisions
RSSCT techniques to predict full-scale GAC useful life time when it is used to
remove dissolved organic matter in drinking water source. This report also
demonstrates how to use pilot-scale testing data to further refine the RSSCT
prediction.
Internal Corrosion Assessment
• Internal Corrosion of Water Distribution Systems (AwwaRF Report 90508,
AwwaRF and DVGW-Technologiezentrum Wasser 1996). This report covers a
wide range of topics related to internal corrosion, such as corrosion principles,
corrosion of various materials including copper alloys and solder, mitigation of
corrosion impacts, assessment technologies, and approaches to corrosion control
studies. This document also describes a bench-scale testing protocol of using various
techniques (such as electrochemical techniques and coupon techniques) to evaluate
corrosion potential. Other useful topics covered by this report include types of
chemicals used for corrosion control, corrosion assessment options for metal
plumbing materials, water quality conditions that affect corrosion of various types of
materials, and benefits and drawbacks of bench testing versus flow-through pipe
loops.
6.3.5 Pilot Testing
Prior to implementing a new technology, some systems may conduct pilot testing to
evaluate technology performance under different design and operating conditions. Tools
described in this section provide guidelines on how to conduct pilot testing. Since technology
development proceeds at a very fast pace in the water industry, to ensure a successful project,
utilities are strongly encouraged to consult with experienced engineers, reputable equipment
providers, and regulatory agencies when planning a pilot testing program.
• Membrane Filtration Guidance Manual (USEPA 2005b). The purpose of this
guidance manual is to provide technical information on the use of membrane filtration
and application of the technology for compliance with the LT2ESWTR, which would
require certain systems to provide additional treatment for Cryptosporidium. Section
6 of this guidance manual provides general guidelines for membrane pilot testing.
Utilities who are considering using membrane technology to comply with
LT2ESWTR should consult with this document before conducting on-site pilot
testing and membrane selection. This document can be found at the following EPA
Web site: http://www.epa.gov/safewater/dismfection/lt2/compliance.html
• Long Term 2 Enhanced Surface Water Treatment Rule: Microbial Toolbox
Guidance Manual (USEPA N.d.e). While there is no specific standardized pilot
testing protocol developed for each of the treatment processes identified in the
LT2ESWTR Toolbox, with the exception of UV and membranes, this Toolbox
Guidance Manual provides general guidance on the Demonstration of Performance
(DOP) protocol that can be used to develop a specific pilot testing protocol for each
treatment technology of interest. The final version of the document will be posted on
EPA's Web site: http://www.epa.gov/safewater/disinfection/lt2/compliance.html
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Internal Corrosion of Water Distribution Systems (AwwaRF Report 90508,
AwwaRF and DVGW-Technologiezentrum Wasser 1996). As described in the
Bench-Scale Testing section, this report provides a wide range of useful information
on internal corrosion, including the description of an on-site pilot testing protocol for
using a single-pass pipe loop tester to evaluate corrosion potential.
6.3.6 Full-Scale Applications
This section provides useful guidelines and tools for utilities to conduct treatment plant
assessment and optimization. The goals for these exercises are to improve treatment
performance and to comply with multiple regulations without major capital expenditure.
Treatment enhancement through these practices is usually achieved by optimizing operating
conditions and minor equipment updates or additions. Major capital improvement, such as the
construction of a new membrane facility, is not within the scope of these plant optimization
protocols, but may be needed after other options are exhausted.
• Comprehensive Performance Evaluations (CPE). Optimizing Water Treatment
Plant Performance Using the Composite Correction Program (USEPA 1998a).
This handbook consists of two components: the Comprehensive Performance
Evaluations (CPE) and Comprehensive Technical Assistance (CTA). The CPE
provides a set of tools that assist a utility to review and analyze its performance-based
capabilities and associated administrative, operations, and maintenance practices.
The goal of CPE is to help a utility to identify factors that might adversely impact a
plant's ability to achieve permit compliance without major capital improvements.
The CTA provides guidance for the performance improvement phase once the CPE
identifies performance improvement potential. Information on this EPA manual can
be found at the following EPA Web site:
http://www. epa. sov/ORD/NRMRL/pubs/62569102 7/62569102 7. htm.
• Partnership for Safe Water Information Center. The Partnership for Safe Water
is a voluntary program organized collaboratively among EPA, AWWA, and other
drinking water organizations to optimize water treatment plant performance above
and beyond regulatory requirements. The Information Center, found at the following
Web site, http://www.awwa.org/science/partnership/InfoCenter/ includes self-
assessment checklists, sample reports, and fact sheets to help a water system get
started.
• Texas Optimization Program (TNRCC 2005). The Texas Optimization Program
(TOP) is a voluntary, non-regulatory program designed to improve the performance
of existing surface water treatment plants without major capital improvements.
Information on TOP can be found at the following Web site:
http://www.tceq.state.tx.us/permitting/water_supply/pdw/swmor/top/.
• Self-Assessment for Treatment Plant Optimization (Lauer 2001). This guidebook
presents protocols on how to optimize conventional treatment plants without
investing in major capital improvements. This document provides procedures for
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6. Making Compliance Decisions
optimizing particulate removal and disinfection through improvements in
administration, maintenance, design, and operations.
• Ultraviolet Disinfection Guidance Manual (USEPA 2006b). Similar to the
Membrane Filtration Guidance Manual, this manual provides guidance on the
validation, selection, design, and operation of ultraviolet (UV) disinfection to comply
with treatment requirements under the LT2ESWTR. The key to the manual is EPA's
recommended protocol for validation of UV reactors. The document is posted on
EPA's web site:
http://www.epa.gOv/safewater/disinfection/l t2/pdfs/guide_lt2_uvguidance.pdf
• Full Scale Implementation of UV in Groundwater Disinfection Systems
(AwwaRF Report No. 90860, Malley et al. 2002). This document identifies key
issues related to full-scale UV implementation, including the importance of UV
reactor hydraulic design, water quality evaluation, sensor calibration, and proper
cleaning techniques to insure optimal UV performance. The report provides specific
guidance for the selection, design, and operation of UV systems.
• Integrating UV Disinfection Into Existing Water Treatment Plants (AwwaRF
Report No. 91086. Cotton et al. 2005.). This document provides user-friendly web
tools that will assist utilities in assessing important disinfection decisions and UV
implementation issues. This report also finds that electric power quality will most
likely not cause a water utility to violate the regulatory requirements on UV
application; however, power quality problems may reduce operational flexibility as
well as UV lamp operations. The analysis protocol for the Cryptosporidium downtime
and off-specification risk assessment could be used to assist regulators in developing
criteria based on Cryptosporidium occurrence and risk.
• Handbook of Public Water Systems, Second Edition (HDR Engineering Inc.
2001). This handbook provides detailed engineering design information for various
drinking water treatment processes, including granular activated carbon.
• Integrated Membrane Systems (AwwaRF Report No. 90899, Schippers et al.
2004). This document provides guidance on the selection, design, and operation of an
integrated membrane system that can function as a synergistic system for removing
microbiological contaminants and DBF precursors. The integrated system may
include membranes (including RO, NF, UF, and MF) and any pre- or post-treatment.
This document also provides procedures for bench and pilot testing for membrane
elements.
• Integrating Membrane Treatment in Large Water Utilities (AwwaRF Report
91045F, Brown and Hugaboom 2004). This study addresses issues related to the
integration of low pressure membranes into existing or planned water treatment
facilities. Results from this study can be used as guidance for membrane layout,
piping, cost comparison, and operations and maintenance.
• NOM Rejection by, and Fouling of, NF and UF Membranes (AwwaRF Report
90837, Amy, Clark and Pellegrino 2001). NF membranes can effectively remove
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6. Making Compliance Decisions
natural organic matter (NOM) from a water supply, while ultrafiltration provides very
limited NOM removal capability. This report provides information on the selection
of appropriate membranes to achieve high NOM rejection, and also presents
information on how water quality (such as the presence of calcium and pH) and
operational conditions might affect NOM rejection by NF membranes.
• Evaluation of Riverbank Filtration as a Drinking Water Treatment Process
(AwwaRF Report No. 90922, Wang, Hubbs and Song 2002). This report describes
the effectiveness of using river bank filtration for the removal of DBF precursors and
microbial contaminants as a function of design and operation variables. This
document also provides general information for riverbank system design and
operation.
6.3.7 Cost Estimation
Accurate cost estimation for facility upgrades requires a comprehensive database that
consists of updated equipment and construction cost information. While engineering consultants
and construction companies usually keep their proprietary cost estimation tools refined and
updated with major cost indices, very few cost estimation tools for the drinking water industry
are available to the general public. The cost estimation tools listed in this section represent the
starting points for budgetary planning. Utility budgetary planning personnel should consult with
the authors of these tools and the additional information sources listed at the end of this section
for a more accurate and updated cost estimation.
• Drinking Water Infrastructure Needs Survey: Modeling the Cost of
Infrastructure (USEPA 2006c). This document provides cost models for water
sources (such as surface water intake, well development, and aquifer storage and
recovery wells), various treatment processes, storage, transmission/distribution
systems, pumping, and other (i.e., SCAD A). The cost of rehabilitation is also
provided along with new installation in some cases. These cost models were designed
for estimating national infrastructure needs and are not applicable to estimating the
costs of specific projects at individual water systems. The document is available at
the following EPA web site:
http://www.epa.gov/ogwdw/needssurvey/pdfs/2003/report_needssurvey_2003_costm
odeling.pdf.
• Water/Wastewater Costs, Windows Version 3.0, (Wesner 2000). This computer
software provides detailed capital and O&M costs of any combination of treatment
processes based on the treatment processes and design criteria selected by the users.
It should be noted that not all of the cost information of every treatment component
were updated during the 2000 revision.
• WTCostO, 2003. This computer program is developed by the U.S. Bureau of
Reclamation and I. Moch & Associates (sponsored by the American Membrane
Technology Association, AMTA) for estimating membrane treatment plant costs. It
allows the evaluation and comparison of water treatment processes that employ
reverse osmosis/nanofiltration, electrodialysis, microfiltration/ultrafiltration, and ion
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6. Making Compliance Decisions
exchange. Using flexible cost indices and adjustable inputs, WTCost includes costs
equations for estimating different pre- and post-treatment unit operations such as
gravity media filtration; coagulation and flocculation with powered activated carbon
(PAC), granulated activated carbon (GAC), alum, ferric chloride, ferrous sulfate, or
polyelectrolyte; disinfection by chlorine, monochloramine, ozone and UV; lime/soda
softening; electrical, including energy recovery, and chemical consumption; and
various intake and outfall infrastructures. Labor and supervision, membrane
replacements, amortization rates, and tanks, piping, and instrumentation are also
included in the cost model, permitting calculation of plant capital requirements, and
operating and maintenance costs. Information on purchasing this tool can be found at
the following Web site: http://www.membranes-amta.org/publications.html .
• WaterCAD (Haestad Methods). This commercial software can be used to design
and analyze distribution systems, including pipelines, and pump stations. With the
Cost Manager component, this program is capable of assessing the capital costs
associated with the water distribution network including pumps, valves, and storage
facilities, and recommends future improvements based on both hydraulic and
financial impacts. Another cost function provided by this program is to estimate
energy costs for constant speed and variable-speed pumps. This program can further
examine the tradeoffs between energy costs and the capital costs required to improve
pump efficiency.
• Technologies and Costs for the Final Long Term 2 Enhanced Surface Water
Treatment Rule and Final Stage 2 Disinfectants and Disinfection Byproducts
Rule (USEPA 2005d). While this publication does not provide system-specific cost
information, systems may use it to determine approximate and relative costs. The
document is available at the following EPA website:
http://www.epa.gov/safewater/disinfection/lt2/pdfs/costs It2-stage2 technologies.pdf
• Technology and Cost Document for the Final Ground Water Rule. (USEPA
2006d). Like the technologies and costs document for the final LT2ESWTR and
Stage 2 DBPR, this cost document does not provide system-specific cost information.
It can, however, be used to evaluate relative costs of different compliance
technologies. The document is available at the following EPA website:
http://www.epa.gov/safewater/disinfection/gwr/pdfs/support_gwr_cost-
technologies.pdf
• Additional Resources for Cost Information
- Most recent cost information or cost curves of a specific technology are published
in professional journals or conference proceedings;
- Utilities from the same region that have conducted similar projects at similar scale
in recent years;
- Reputable equipment suppliers; and
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6. Making Compliance Decisions
- Reputable engineering consultants.
6.3.8 Community Preferences
This section includes recently published AwwaRF research reports that provide utility
survey data and practical guidance to assist water utilities in improving their customer
communications, public perception, and public involvement of the water quality issues,
regulatory compliance issues, and potential capital improvement projects.
• Consumer Attitude Survey Update (AwwaRF Report No. 394, AwwaRF 2000).
This report discusses trends in public confidence and expectations, perceptions, and
satisfaction. Also identified in this report are the driving factors behind these
attitudes and trends and the impact of media on public confidence and customer
satisfaction. The implications of these findings for measuring customer attitudes at
the local utility level are also discussed.
• Tools and Methods to Effectively Measure Customer Perceptions (AwwaRF
Report No. 90856, Colbourne 2001). This report evaluates available assessment
tools and methods that measure customer perceptions and changes in their opinions
toward drinking water utilities and utility services.
• Best Practices for a Continually Improving Customer Responsive Organization
(AwwaRF Report 90868, Olstein 2001). This report provides case studies of five
successful customer-driven water utilities that have used different approaches to
achieving a continually improving customer-responsive organization. This document
presents public input to the best practices, and a toolkit for utilities that includes a
self-assessment questionnaire, a technology identification matrix, and benchmarking
data.
• Public Involvement... Making It Work (AwwaRF Report 90865, Nero et al.
2001). In 1995, AwwaRF published the Public Involvement Strategies: A Manager's
Handbook (AwwaRF 1995) to provide a framework for building consensus on
difficult decisions. It presents a ten-step process to help water utility managers
identify, understand, and plan public involvement and project implementation. This
new report reduces the ten-step public involvement process to three essential steps,
and provides a new handbook to guide utility managers through the public
involvement process.
• Public Involvement Strategies on the Web (AwwaRF 2003). This web-based
interactive tool was provided by AwwaRF in 2003 to expand the AwwaRF Report
90865 (Nero et al. 2001) by offering public involvement case studies and interactive
features on the internet. This interactive tool can be found at the following AwwaRF
Web site:
http://www.awwarf.org/research/TopicsAndProjects/Resources/webTools/ch2m/defau
It.html.
• Customer Attitudes, Behavior and the Impact of Communications Efforts
(AwwaRF Report 90975, Tatham, Tatham and Mobley 2004). This report
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provides guidelines on the following three areas that are critical to communication
with customers: (1) determine whether or not communication can be used as a tool by
water utilities to positively affect the attitudes and behaviors of residential water
utility customers, (2) identify the types of information that should be communicated
by water utilities to enhance customer satisfaction and the methods for
communicating this information to customers, and (3) report on ways to inform
customers about water quality issues and provide guidance on communication
strategies. This report includes a CD-ROM that contains 18 Microsoft Word
documents that illustrate the survey data for various demographic groups.
• Effective Practices to Select, Acquire, and Implement a Utility CIS (AwwaRF
Report 91071, Rettie et al. 2005). This report provides guidance to utilities as they
select, acquire, and implement a customer information system (CIS). Guidelines
provided in this document focus on four areas: (1) characterizing the current status of
water utilities regarding CIS solutions, (2) identifying and documenting critical
success factors (and barriers to success) related to CIS implementations, (3)
documenting successful CIS implementations and associated practices, and (4)
providing a CIS projects roadmap for utilities.
• Strategic Communication Planning: A Guide for Water Utilities (AwwaRF
Report 91106, Mobley et al. 2006). This report discusses the role of strategic
communication planning in the overall performance and success of drinking water
utilities. It establishes the link between high trust and credibility and the ability to
communicate effectively. It provides a guidebook that integrates key findings from
past research and this project to help drinking water utilities develop strategic
communication plans.
6.4 Basic Approach for Implementing Regulatory Compliance Projects
The implementation of a project to accomplish regulatory compliance involves several
stages, including planning, design, implementation, and on-going evaluation. Exhibit 6.2
illustrates how the tools discussed in this chapter can be used to accomplish these various project
implementation stages.
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6. Making Compliance Decisions
In the planning stage, the project objective(s) should be defined and the data needs for
meeting these objectives should be identified. In addition, the project team should seek input
from all interested parties to confirm that the project has the correct focus and direction. The
planning process typically includes an evaluation and comparison of various compliance options
based on cost, treatment performance and other system-specific factors such as customer
preferences.
Implementation
On-going Evaluation
Once a compliance option has been selected, the design stage is initiated to develop
specific design criteria such as chemical dosage rates, equipment sizing, and plans for integrating
new treatment processes with existing facilities. Further testing may be warranted during the
design stage to establish design and operating criteria under expected treatment conditions.
Exhibit 6.2 Application of Information Gathering Tools at Various Project Implementation
Stages
Tool Type
Water quality monitoring
Hydraulic and water
quality modeling for
distribution systems
Desktop evaluations
Bench-scale testing
Pilot testing
Full-scale applications
Cost estimation
Community preferences
Planning
X
X
X
X
X
X
X
X
Design
X
X
X
Implementation
X
X
X
X
X
On-going
Evaluation
X
X
X
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March 2007
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6. Making Compliance Decisions
Project implementation is the process of carrying out the project as designed and may
involve site and building construction, equipment installation, and start-up operations. Water
quality monitoring activities during this stage may focus on possible construction impacts to
finished water quality and the local environment. Additional testing may be needed to address
issues raised during start-up operations.
Once a project has been implemented, information should be gathered on an on-going
basis to further optimize system operation, finished water quality, and O&M costs. Customer
feedback is important at this stage to assure that the project has not caused unforeseen secondary
impacts to water quality or customer service. Water quality monitoring may be intensive when
new facilities are first put into service.
The approach used by Owenton Water Works and Kentucky American Tri-Village in
solving their simultaneous compliance issue (as described in Case Study # 1 in Appendix B) is
summarized as an example. Rather than switching to a higher quality source of supply, the water
systems decided to take a less expensive approach by changing chlorination practices at the
existing treatment facility to reduce TTHM. The approach included the following specific steps:
Planning
• Identified primary objective (reducing TTHM);
• Collected existing water quality data from both systems to define causative factors for
elevated DBFs; and
• Considered costs of different compliance options (developing new source vs.
modifying existing treatment).
Design
• Collected profiles of TOC removal, TTHM formation, and disinfection through the
plant and distribution system;
• Conducted tracer studies to assess in-plant disinfection contact time; and
• Developed design drawings and specifications for new chlorine feed equipment.
Implementation
• Initiated enhanced coagulation at lower pH;
• Optimized potassium permanganate feed to raw water to control source water
manganese;
• Revised operational guidelines to increase hydraulic retention time in plant clearwell;
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6. Making Compliance Decisions
• Moved chorination point; and
• Optimized chlorine dosage rates at distribution system booster stations.
On-going Evaluation
• Evaluated results of enhanced coagulation process change;
• Evaluated results of potassium permanganate feed changes; and
• Continued to conduct special distribution system water quality monitoring.
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7. References
7 References
The references in this chapter have been organized as follows under the following headings in
Section 7.1, with a complete alphabetical list in Section 7.2:
7.1 References Organized by Topic 7-1
7.1.1 General 7-1
7.1.2 Formation and Control of Chlorinated DBFs 7-9
7.1.3 Corrosion 7-10
7.1.4 Source Management 7-13
7.1.5 Distribution System Management 7-14
7.1.6 Problem Organisms in Water Treatment 7-16
7.1.7 Pre-sedimentation 7-17
7.1.8 Enhanced Coagulation and Enhanced Softening 7-17
7.1.9 GAC 7-19
7.1.10 Membranes 7-20
7.1.11 Riverbank Filtration 7-21
7.1.12 Chloramines 7-22
7.1.13 Ozone 7-25
7.1.14 Ultraviolet Light 7-27
7.1.15 Chlorine Dioxide 7-28
7.1.16 Tools for Gathering More Information 7-29
7.1.17 Chlorination 7-35
7.2 Comprehensive List of References 7-38
7.1 References Organized by Topic
7.1.1 General
Angers, J. 2001. Question of the Month: Which Disinfectant Will Work Best for Us?
Opflow. 27(5): 6-7, 22.
AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York:
McGraw-Hill.
AWWA. 1999c. Water Quality and Treatment: A Handbook of Community Water
Supplies. 5th Edition. Letterman, R.D. (editor). New York: McGraw-Hill.
AWWA. 1999d. Design and Construction of Small Water Systems. 2nd Edition. 228 pp.
Denver: AWWA.
AWWA. 1999e. Hydraulic Design Handbook. Mays, L.W.(editor). New York: McGraw-
Hill.
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7. References
AWWA. 2000. Operational Control of Coagulation and Filtration Processes. 2nd
Edition. AWWA Manual M37. pp. 1-34. Denver: AWWA.
AWWA. 2004e. Recommended Practice for Backflow Prevention and Cross-Connection
Control. 3rd Edition. AWWA Manual M14. Denver: AWWA.
AWWA. 2005c. Disinfecting Water Mains. AWWA Standard C651-05. Denver:
AWWA.
AwwaRF and Lyonnaise des Eaux. 1995. Advances in Taste and Odor Treatment and
Control. AwwaRF Report 90610. Project #629. Denver: AwwaRF.
Becker, W.C., K. Au, C.R. O'Melia, and J.S. Young, Jr. 2004. Using Oxidants to
Enhance Filter Performance. AwwaRF Report 90998. Project #2725. Denver: AwwaRF.
Bevery, R. P. 2005. Filter Troubleshooting and Design Handbook. 425 pp. Denver:
AWWA.
Burlingame, G.A., A.M. Dietrich, T. Gittleman, and R.C. Hoehn. 2004. Practical Taste-
and-Odor Methods for Routine Operations: Decision Tree. AwwaRF Report 91019.
Project #467. Denver: AwwaRF.
Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver:
AWWA.
Gulp, G.L. and R.L. Gulp. 1974. New Concepts in Water Purification. New York: Van
Norstrand Reinhold Co.
DeMers, L.D. and R.C. Renner. 1993. Alternative Disinfection Technologies for Small
Drinking Water Systems. AwwaRF Report 90619. Project #621. Denver: AwwaRF.
Dewettinck T., E. Van Houtte, D. Geenens, K. Van Hege, and W. Verstraete. 2001.
HACCP (Hazard Analysis and Critical Control Points) to Guarantee Safe Water Reuse
and Drinking Water Production—a Case Study. Water Science and Technology. 43(12):
31-8.
DeWolfe, J., B. Dempsey, M. Taylor, and J. Potter. 2003. Guidance Manual for
Coagulant Changeover. AwwaRF Report 90958. Project #2512. Denver: AwwaRF.
Faust, S. and O. Aly. 1998. Chemistry of Water Treatment. 2nd Edition. New York:
Lewis Publishers.
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-------
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7.1.2 Formation and Control of Chlorinated DBFs
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7.1.3 Corrosion
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leaks in residential plumbing. Water Science and Technology. 49(2): 83-90.
Estes-Smargiassi, S., and A. Cantor. 2006. Lead Service Line Contributions to Lead at
the Tap. In Proceedings AWWA Water Quality Technology Conference. Denver:
AWWA. November 2006.
Estes-Smargiassi, S., J. Steinkrauss, A. Sandvig, and T. Young. 2006. Impact of Lead
Service Line Replacement on Lead Levels at the Tap. In Proceedings AWWA Annual
Conference and Exposition. San Antonio: AWWA. June, 2006.
Kirmeyer, G.J., J. Clement, and A. Sandvig. 2000a. Distribution System Water Quality
Changes Following Implementation of Corrosion Control Strategies. AwwaRF Report
90764. Project #157. Denver: AwwaRF.
Kirmeyer, G.J., B.M. Murphy, A. Sandvig, G. Korshin, B. Shaha, M. Fabbricino, and G.
Burlingame. 2004b. Post Optimization of Lead and Copper Control Monitoring
Strategies. AwwaRF Report 90996F Project #2679. Denver: AwwaRF.
Simultaneous Compliance Guidance Manual 7-11 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
7. References
Kirmeyer, G.J., A.M. Sandvig, G.L. Pierson, and C.H. Neff. 1994. Development of a
Pipe Loop Protocol for Lead Control. AwwaRF Report 90650 Project #604. Denver:
AwwaRF.
Korshin, G.V. and J.F. Ferguson. 1999. Corrosion and Metal Release for Lead
Containing Materials: Influence of NOM. AwwaRF Report 90759 Project #182.
Denver: AwwaRF.
Lytle, D.A. and M.R. Schock. 2005. The Formation of Pb(IV) Oxides in Chlorinated
Water. Journal of American Water Works Association. 97(11): 102.
Maas, R.P., J.C. Pitch, and A.M. Smith. 2005. Effects of Fluorides and Chloramines on
Lead Leaching from Leaded-Brass Surfaces. Asheville Environmental Quality Institute
Technical Report #04-137
Marshall, B., J. Rushing, and M. Edwards. 2003. Confirming the role of aluminum solids
and chlorine in copper pitting corrosion. In Proceedings ofAWWA Annual Conference.
Denver: AWWA.
Rego, C.A. and M.R. Schock. 2007. Case Studies in the Integrated Use of Scale Analyses
to Solve Lead Problems. In Proceedings of Distribution System Research Symposium.
Denver: AWWA.
Rushing, J.C., and M. Edwards. 2002. Effect of aluminum solids and chlorine on cold
water pitting of copper. In Proceedings ofAWWA Water Quality Technology Conference.
Sarin, P., J.A. Clement, V.L. Snoeyink, and W.M. Waltraud. 2003. Iron Release from
Corroded, Unlined Cast-Iron Pipes. Journal of American Water Works Association.
95(11): 85-96.
Sarin, P., V.L. Snoeyink, J. Bebee, K.K. Jim, M.A. Beckett, W.M. Kriven, and J.A.
Clement. 2004. Iron Release from Corroded Iron Pipes in Drinking Water Distribution
Systems: Effect of Dissolved Oxygen. Water Research. 38: 1259-1269.
Schock, M. 1996. Corrosion Inhibitor Applications in Drinking Water Treatment:
Conforming to the Lead and Copper Rule. Presented atNACE Corrosion 1996
Conference.
Schock, M.R., 2001. Tetravalent Lead: A Hitherto Unrecognized Control of Tap Water
Lead Contamination. In Proceedings ofAWWA Water Quality Technology Conference.
Denver: AWWA.
Schock, M.R. and J.C. Fox. 2001. Solving Copper Corrosion Problems while Maintaining
Lead Control in a High Alkalinity Water using Orthophosphate. Presented at the Ohio
AWWA Annual Conference. August 30, 2001. Cleveland: AWWA.
Schock, M.R. and R. Giani. 2004. Oxidant/Disinfectant Chemistry and Impacts on Lead
Corrosion. In Proceedings ofAWWA Water Quality Technology Conference. Denver:
AWWA.
Schock, M.R., K.G. Scheckel, M. DeSantis, and T.L. Gerke. 2005. Mode of Occurrence,
Treatment and Monitoring Significance of Tetravalent Lead. In Proceedings ofAWWA
Water Quality Technology Conference. Denver: AWWA.
Simultaneous Compliance Guidance Manual 7-12 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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7. References
Schock, M.R., I. Wagner, and R. Oliphant. 1996. The Corrosion and Solubility of Lead in
Drinking Water. In Internal Corrosion of Water Distribution Systems. 2nd edition.
AwwaRF and DVGW TZW Cooperative Research Report. AwwaRF Report 90508.
Project #725. Denver: AwwaRF.
USEPA. 2002c. Lead and Copper Monitoring and Reporting Guidance for Public Water
Systems. Office of Water. EPA 816-R-02-009.
USEPA. 2003h. Revised Guidance Manual for Selecting Lead and Copper Control
Strategies. Office of Water. EPA 816-R-03-001. March, 2003.
Valentine, R. 2001. Mechanisms and Kinetics of Chloramine Loss and By-Product
Formation in the Presence of Reactive Drinking Water Distribution System Constituents.
Washington, D.C.: USEPA
Veazey, M. V. 2004. New Research May Explain Pinholes in Copper Tubing. Materials
Performance. 43(5): 18-22.
7.1.4 Source Management
Cooke, G.D. and R.E. Carlson. 1989. Reservoir Management for Water Quality and THM
Precursor Control. AwwaRF Report 90569. Project #308. Denver: AwwaRF.
Cooke, G.D. and R.H. Kennedy. 2001. Managing drinking water supplies. Lake and
Reservoir Management. 17(3): 157-174.
Effler, S.W., D.A. Matthews, M. T. Auer, M. Xiao, B.E. Forrer, and E.M. Owens. 2005.
Origins, Behavior, and Modeling of THM Precursors in Lakes and Reservoirs. AwwaRF
Report 91057F. Project #557. Denver: AwwaRF.
Faust, S. and O. Aly. 1998. Chemistry of Water Treatment. 2nd Edition. New York:
Lewis Publishers.
Grayman, W.M., R.A. Deininger, and R.M. Males. 2001. Design of Early Warning and
Predictive Source-Water Monitoring Systems. AwwaRF Report 90878. Project #2527'.
Denver: AwwaRF.
Knappe, D.R.U., R.D. Belk, D.S. Briley, S.R. Gandy, N. Rastogi, A.H. Rike, H.
Glasgow, E. Hannon, W.D. Frazier, P. Kohl, and S. Pugsley. 2004. Algae Detection and
Removal Strategies for Drinking Water Treatment Plants. AwwaRF Report 90971.
Project #360. Denver: AwwaRF.
Kornegay, B.H. 2000. Natural Organic Matter in Drinking Water: Recommendations to
Water Utilities. AwwaRF Report 90802. Project #2543. Denver: AwwaRF.
USEPA. 2006f. Source Water Monitoring Guidance Manual for Public Water Systems
for the Long Term 2 Enhanced Surface Water Treatment Rule. Office of Water. EPA
815-R-06-005. February 2006.
http://www.epa.gov/safewater/disinfection/lt2/pdfs/guide It2 swmonitoringguidance.pdf
Simultaneous Compliance Guidance Manual 7-13 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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7. References
7.1.5 Distribution System Management
AWWA. 1996. Water Transmission and Distribution. 2nd Edition. Denver: AWWA.
AWWA. 1998. Distribution System Requirements for Fire Protection. 3rd Edition.
AWWA Manual M31. 63 pp. Denver: AWWA.
AWWA. 2001b. Elevated Water Storage Tanks: Maintenance. VHS Video. Denver:
AWWA.
AWWA. 2002. Unidirectional Flushing. DVD. Denver: AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water
Transmission and Distribution. 3rd Edition. 553 pp. Denver: AWWA.
AWWA. 2003b. Sizing Water Service Lines and Meters. 2nd Edition. AWWA Manual
M22. 112 pp. Denver: AWWA.
AWWA. 2004a. Computer Modeling of Water Distribution Systems. AWWA Manual
M32. 160 pp. Denver: AWWA.
AWWA. 2004c. G200-04: Distribution Systems Operation and Management. 16 pp.
Denver: AWWA.
AWWA. 2005b. Distribution System Water Quality Challenges in the 21st Century -A
Strategic Guide. MacPhee, MJ. (Editor). 190 pp. Denver: AWWA.
AWWA. 2005c. Disinfecting Water Mains. AWWA Standard C651-05. Denver:
AWWA.
AWWA and AwwaRF. 1992. Water Industry Database: Utility Profiles. Denver:
AWWA.
Brandt, M.J., J. Clement, J. Powell, R. Casey, D. Holt, N. Harris, and C.T. Ta. 2004.
Managing Distribution System Retention Time to Improve Water Quality. Denver:
AwwaRF.
Camper, A.K. and W.L. Jones. 2000. Factors AffectingMicrobial Growth in Model
Distribution Systems. AwwaRF Report 90785. Project #183. Denver: AwwaRF.
Cesario, A. L. 1995. Modeling, Analysis, and Design of Water Distribution Systems.
Denver: AWWA.
Clark, R.M., and W.M. Grayman. 1998. Modeling Water Quality in Drinking Water
Distribution Systems. 231 pp. Denver: AWWA.
Clement, J., Powell, M. Brandt, R. Casey, D. Holt, W. Grayman, and M. LeChevallier.
2005. Predictive Models for Water Quality in Distribution Systems. AwwaRF Report
91023F. Project #2865. Denver: AwwaRF.
DeNadai, A.J., H.M. Gorrill, Y.J. Hasit, S.B. McCammon, R.S. Raucher, and J.
Whitcomb. 2004. Cost and Benefit Analysis of Flushing. Denver: AWWA and AwwaRF.
Escobar, I.C., A.A. Randall, and J. S. Taylor. 2001. Bacterial Growth in Distribution
Systems: Effect of Assimilable Organic Carbon and Biodegradable Dissolved Organic
Carbon. Environmental Science and Technology. 35(17): 3442-3447.
Simultaneous Compliance Guidance Manual 7-14 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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7. References
Friedman, M.J., G. Kirmeyer, G. Pierson, S. Harrison, K. Martel, A. Sandvig, and A.
Hanson. 2005. Development of Distribution System Water Quality Optimization Plans.
Denver: AwwaRF.
Friedman, M., K. Martel, A. Hill, D. Holt, S. Smith, T. Ta, C. Sherwin, D. Hiltebrand, P.
Pommerenk, Z. Hinedi, and A. Camper. 2003. Establishing Site-Specific Flushing
Velocities. Denver: AwwaRF.
Grayman, W.M., L.A. Rossman, C. Arnold, R.A. Deininger, C. Smith, J.F. Smith, and R.
Schnipke. 2000. Water Quality Modeling of Distribution System Storage Facilities.
AwwaRF Report 90774. Projct #260. Denver: AwwaRF.
Haestad Methods. WaterCAD. Water Distribution Modeling & Management Software.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D.
Smith, M. LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesen, and R. Gushing.
2000b. Guidance Manual for Maintaining Distribution System Water Quality. AwwaRF
Report 90798. Project #357. Denver: AwwaRF.
Kirmeyer, G.J., M. Friedman, K. Martel, G. Thompson, A. Sandvig, J. Clement, and M.
Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality.
AwwaRF Report 90882. Project #2522. Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
LeChevallier, M.W., C.D. Cawthorn, and R.G. Lee. 1988b. Inactivation of Biofilm
Bacteria. Applied andEnvironmentalMicrobiology. 54(10): 2492-2499.
LeChevallier, M.W., C.D. Lowry, and R.G. Lee. 1990. Disinfection of Biofilms in a
Model Distribution System. Journal of American Water Works Association. 82(7): 87-99.
LeChevallier, M.W., C.D. Lowry, R.G. Lee, and D.L. Gibbon. 1993. Examining the
Relationship Between Iron Corrosion and the Disinfection of Biofilm Bacteria. Journal
of American Water Works Association. 85(7): 111-123.
LeChevallier, M.W., N.J. Welch, and D.B. Smith. 1996. Full scale studies of factors
related to coliform regrowth in drinking water. Applied and Environmental Microbiology.
62(7): 2201-2211.
Liu, W., H. Wu, Z. Wang, S.L. Ong, J.Y. Hu and WJ. Ng. 2002. Investigation of
Assimilable Organic Carbon (AOC) and Bacterial Regrowth in Drinking Water
Distribution System. Water Research. 36(4): 891-898.
Lowther, E.D. and R.H. Mosher. 1984. Detecting and Eliminating Coliform Regrowth. In
Proceedings of AWWA Water Quality Technology Conference. Denver: AWWA.
Martel, K., G. Kirmeyer, A. Hanson, M. Stevens, J. Mullenger, and D. Deere. 2006.
Application ofHACCPfor Distribution System Protection. AwwaRF Report 91131.
Project #2856. Denver: AwwaRF.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Najm, I. 2000. Case Studies of the Impacts of Treatment Changes on Biostability in Full-
Scale Distribution Systems. AwwaRF Report 90816. Project #361. Denver: AwwaRF.
Simultaneous Compliance Guidance Manual 7-15 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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7. References
National Research Council. 2006. Drinking Water Distribution Systems: Assessing and
Reducing Risks. Washington, D.C.: The National Academies Press.
Pierson, G., K. Martel, A. Hill, G. Burlingame, and A. Godfree. 2001. Practices to
Prevent Microbiological Contamination of Water Mains. Denver: AwwaRF and AWWA.
Roberts, P.J.W., X. Tian, F. Sotiropoulos, andM. Duer. 2006. Physical Modeling of
Mixing in Water Storage Tanks. Denver: AWWA.
Schock, M.R. 2005. Chapter 6: Distribution Systems as Reservoirs and Reactors for
Inorganic Contaminants. In Distribution System Water Quality Challenges in the 21st
Century. Denver: AWWA.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp.
Denver: AWWA.
Snyder, J.K. and AK. Deb. 2002. Impacts ofFireflow on Distribution System Water
Quality, Design, and Operation. AwwaRF Report 90913. Project #2554. Denver:
AwwaRF.
Tikkanen, M., J.H. Schroeter, L.Y.C. Leong, and R. Ganesh. 2001. Guidance Manual for
Disposal of Chlorinated Water. AwwaRF Report 90863. Project #2513. Denver:
AwwaRF.
USEPA. 1992a. Control of Biofilm Growth in Drinking Water Distribution Systems.
Office of Research and Development. EPA 625/R-92/001.
USEPA. 2006a. Initial Distribution System Evaluation Guidance Manual for the Final
Stage 2 DBPR. Office of Water. EPA 815-B-06-002.
Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278
pp. Denver: AWWA.
White, G.C. 1992. Handbook of Chlorination and Alternative Disinfectants. 3rd Edition.
New York: Van Nostrand Reinhold Co.
7.1.6 Problem Organisms in Water Treatment
AWWA. 2003c. Problem Organisms in Water: Identification and Treatment (M7). 3rd
edition. 155 pp. Denver: AWWA.
Belanger, Scott E., D.S. Cherry, J.L. Farris, K.G. Sappington, and J. Cairns, Jr. 1991.
Sensitivity of the Asiatic Clam to Various Biocidal Control Agents. Journal of American
Water Works Association. 83(10): 79-87.
Britton, J.C. and B. Morton. 1982. A dissection guide, field and laboratory manual for the
introduced bivalve Corbicula fluminea. Malacological Review Supplement. 3:1-82.
Cameron, G.N., J.M. Symons, S.R. Spencer, and J.Y. Ma. 1989. Minimizing THM
Formation During Control of the Asiatic Clam: A Comparison of Biocides. Journal of
American Water Works Association. 81(10):53-62.
Counts, C. L., III. 1986. The zoogeography and history of the invasion of the United
States by Corbicula fluminea (Bivalvia: Corbiculidae). American Malacological Bulletin,
Simultaneous Compliance Guidance Manual 7-16 March 2007
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7. References
Special Edition No. 2. In Proceedings of the Second International Corbicula Symposium.
pp. 7-39.
Lange, C. L., T. M. Short, and E. Blake. 1994. Development of Zebra Mussel Control
Strategies for a Coalition of Vermont Water Suppliers on Lake Champlain. In
Proceedings of the Fourth International Zebra Mussel Conference. Madison, WI.
Stevenson, B. 1997. Controlling Zebra Mussels at Water Treatment Plant Intakes.
AwwaRF Report 90612. Project #614. Denver: AwwaRF.
Stevenson, B. 1999. Controlling Zebra Mussels at Water Treatment Plant Intakes Part II.
AwwaRF Report. Project #821. Denver: AwwaRF.
7.1.7 Pre-sedimentation
AWWA. 2000. Operational Control of Coagulation and Filtration Processes. 2nd
Edition. AWWA Manual M37. pp. 1-34. Denver: AWWA.
Kawamura, S. 2000. Integrated Design and Operation of Water Treatment Facilities. 2nd
Edition. New York: John Wiley & Sons, Inc.
USEPA. 1998a. Handbook: Optimizing Water Treatment Plant Performance Using the
Composite Correction Program. EPA 625/6-91/027.
USEPA. N.d.e. LT2ESWTR Microbial Toolbox Guidance Manual. Office of Water.
7.1.8 Enhanced Coagulation and Enhanced Softening
Gates, D. 1997. The Chlorine Dioxide Handbook. 177pp. Denver: AWWA.
Hering, J.G., P.Y. Chen, J.A. Wilkie, M. Elimelech, and S. Liang. 1996. Arsenic removal
by ferric chloride. Journal of American Water Works Association. 88(4): 155-167.
Hoehn, R.C. 1993. Chlorine Dioxide Use in Water Treatment. Key Issues Proceedings,
2nd Inter national Symposium, Chlorine Dioxide and Drinking Water Issues, pp. 1-14.
Houston, TX.
Kirmeyer, G.J., M. Friedman, K. Martel, G. Thompson, A. Sandvig, J. Clement, and M.
Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality.
AwwaRF Report 90882. Project #2522. Denver: AwwaRF and AWWA.
Krasner, S.W. and G. Amy, 1995. Jar-test evaluations of enhanced coagulation. Journal
of American Water Works Association. 87(10): 93-107.
Logsdon, G., A. Hess, P. Moorman, and M. Chipps. 2000. Turbidity Monitoring and
Compliance for the Interim Enhanced Surface Water Treatment Rule. Denver: AWWA.
Lovins, W.A., III, S.J. Duranceau, R.M. Gonzalez, and J.S. Taylor. 2003. Optimized
Coagulation Assessment for a Highly Organic Surface Water Supply. Journal of
American Water Works Association. 95(10): 94-108.
Marshall, B., J. Rushing, and M. Edwards. 2003. Confirming the role of aluminum solids
and chlorine in copper pitting corrosion. In Proceedings of AWWA Annual Conference.
Denver: AWWA.
Simultaneous Compliance Guidance Manual 7-17 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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7. References
Montgomery Watson Inc. 1998. Palm Beach County Water Utilities Department Water
Treatment Plant No. 3. Membrane Softening Facility Operations Manual Final Report.
pp. 4-19 to 4-20.
Randtke, S.J., and R.C. Hoehn. 1999. Removal of DBF precursors by Enhanced
Coagulation and Lime Softening. AwwaRF Report 90783. Project #814. Denver:
AwwaRF.
Randtke, S.J., C.E. Thiel, M.Y. Liao, and C.N. Yamaya. 1982. Removing Soluble
Organic Contaminants by Lime-Softening. Journal of American Water Works
Association. 74(4): 192.
Reckhow, D.A. 1999. Control of Disinfection Byproduct Formation Using Ozone. In
Formation and Control of Disinfection By-Products in Drinking Water. Singer, P.C.
(editor), pp. 179-204. Denver: AWWA.
Rushing, J.C., and M. Edwards. 2002. Effect of aluminum solids and chlorine on cold
water pitting of copper. In Proceedings of AWWA Water Quality Technology Conference.
Scott, K.N., J.F. Green, H.D. Do, and SJ. McLean. 1995. Arsenic Removal by
Enhanced Coagulation. Journal of American Water Works Association. 87(4): 114-126.
Schock, M. 1996. Corrosion Inhibitor Applications in Drinking Water Treatment:
Conforming to the Lead and Copper Rule. Presented atNACE Corrosion 1996
Conference.
Shorney, H.L., and SJ. Randtke. 1994. Enhanced Lime Softening for the Removal of
Disinfection By-Product Precursors. In Proceedings of 1994 Annual AWWA Conference.
Denver: AWWA.
Singer, P.C. (editor). 1999. Formation and Control of Disinfection By-Products in
Drinking Water. 424 pp. Denver: AWWA.
Sorg, TJ. 1988. Methods for Removing Uranium from Drinking Water. Journal of
American Water Works Association. 80(7): 105-111.
States, S., R. Tomko, M. Scheuring, and L. Casson. 2002. Enhanced coagulation and
removal of Cryptosporidium. Journal of American Water Works Association. 94(11): 67-
77.
Thompson, P.L., and W.L. Paulson 1998. Dewaterability of Alum and Ferric Coagulation
Sludges. Journal of American Water Works Association. 90(4): 164-170.
USEPA. 1991. Guidance Manual for Compliance with the Filtration and Disinfection
Requirements for Public Water Systems Using Surface Water Sources. Developed by
Malcolm Pirnie and HDR. 568 pp. Washington D.C.: USEPA.
USEPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening Guidance
Manual. EPA 815-R-99-012.
USEPA. 200Ih. Low-Pressure Membrane Filtration for Pathogen Removal: Application,
Implementation, and Regulatory Issues. Office of Water. EPA 815-C-01-001.
http://www.epa.gov/OGWDW/disinfecti on/1 t2/pdfs/report_lt2_membranefiltration.pdf
USEPA. 2005c. A Regulator's Guide to the Management of Radioactive Residuals from
Drinking Water Treatment Technologies. USEPA 816-R-05-004.
Simultaneous Compliance Guidance Manual 7-18 March 2007
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7. References
USEPA. N.d.e. LT2ESWTR Microbial Toolbox Guidance Manual. Office of Water.
Forthcoming, http://www.epa.gov/safewater/disinfection/lt2/compliance.html
Williams, M.D., B.M. Coffey, and S.W. Krasner, 2003. Evaluation of pH and Ammonia
for Controlling Bromate During Cryptosporidium Disinfection. Journal of American
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7.1.9 GAC
American Chemical Society. 1983. Treatment of Water by Granular Activated Carbon.
Advances in Chemistry Series Number 202. MJ. McGuire and I.H. Suffet (editors).
Washington, D.C.: American Chemical Society.
Crittenden, J.C. 1989. Prediction of GAC Performance Using Rapid Small-Scale Column
Tests. AwwaRF Report 90549. Project #230. Denver: AwwaRF.
Klotz, M., P. Werner, and R. Schweisfurth. 1976. Investigations concerning the
microbiology of activated carbon filters, pp. 312-330. H. Sontheimer (editor). Translation
of Reports on Special Problems of Water Technology. Volume 9 Adsorption. Conference
held in Karlsruhe, Federal Republic of Germany. USEPA, Municipal Environmental
Research Laboratory, Cincinnati, OH. Report No. EPA 600/9-76-030.
Leung, K.S. and R.L. Segar. 2000. Adsorption Interactions of S-Triazine Herbicide with
Trace Organics in a GAC Filter-Absorber. Presented at the AWWA Conference. Denver:
AWWA.
McTigue, N. andD. Cornwell. 1994. The Hazardous Potential of Activated Carbons
Used in Water Treatment. AwwaRF Report 90640. Project #620. Denver: AwwaRF.
Najm, I, M. Kennedy, and W. Naylor. 2005. Lignite versus Bituminous GAC for
Biofiltration - A Case Study. Journal of American Water Works Association. 97(1): 94-
101.
Owen, D.M. 1998. Removal of DBF Precursors by GAC Adsorption. AwwaRF Report
90744. Project #816. Denver: AwwaRF.
USEPA. 2003d. Technologies and Costs for Control of Microbial Contaminants and
Disinfection Byproducts. Office of Ground Water and Drinking Water. Washington, D.C.
Xie, Y., H. Wu, and H. Tung. 2004. Haloacetic AcidRemoval Using Granular Activated
Carbon. AwwaRF Report 91041F. Project #2825. Denver: AwwaRF.
Youngsug, K., L. Yeongho, C.S. Gee, and C. Euiso. 1997. Treatment of Taste and Odor
Causing Substances in Drinking Water. Water Science and Technology. 35(8): 29-36.
Parson, F., P.R. Wood, and J. DeMarco. 1980. Bacteria associated with granular activated
carbon columns. In Proceedings of AWWA Technology Conference, p.271-296. Denver:
AWWA.
Krasner, S.W., S.R. Rajachandran, I.E. Cromwell III, D.M. Owen, and Z.K. Chowdhury.
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Simultaneous Compliance Guidance Manual 7-19 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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7. References
HDR Engineering, Inc. 2001. Handbook of Public Water Systems. 2nd Edition. New
York: John Wiley & Sons, Inc.
USEPA. 200Ih. Low-Pressure Membrane Filtration for Pathogen Removal: Application,
Implementation, and Regulatory Issues. Office of Water. EPA 815-C-01-001.
http://www.epa.gov/OGWDW/disinfection/lt2/pdfs/report It2 membranefiltration.pdf
7.1.10 Membranes
Adham, S., K. Chiu, K. Gramith, and J. Oppenheimer. 2005. Development of a
Microfiltration and Ultrafiltration Knowledge Base. AwwaRF Report 91059. Project
#2763. Denver: AwwaRF.
Amy, G., M. Clark, and J. Pellegrino. 2001. NOMRejection by, and Fouling of, NF and
UFMembranes. AwwaRF Report 90837. Project #390. Denver: AwwaRF.
Amy, G.L., M. Edwards, M. Benjamin, K. Carlson, J. Chwirka, P. Brandhuber, L.
McNeill, and F. Vagliasindi. 2000. Arsenic Treatability Options and Evaluation of
Residuals Management Issues. AwwaRF Report 90771. Project #153. Denver: AwwaRF.
AWWA. 1999. Reverse Osmosis andNanofiltration. AWWA Manual M46. Denver:
AWWA.
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water
Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver:
AwwaRF.
Brown, J. and and D. Hugaboom. 2004. Integrating Membrane Treatment in Large Water
Utilities. AwwaRF Report 91045F. Project #2876. Denver: AwwaRF.
Chang, S.D., W.D. Bellamy, and H. Ruiz. 1994. Removal of Arsenic by Enhanced
Coagulation and Membrane Technology. In Proceedings AWWA Annual Conference.
New York: AWWA.
Duranceau, S.J. 2001. Membrane Practices for Water Treatment. Denver: AWWA.
Glucina, K., A. Alvarez, and J.M. Laine. 2000. Assessment of an integrated membrane
system for surface water treatment. In Proceeding of the conference in drinking and
industrial water production. Italy. 2:113-122.
HDR Engineering, Inc. 2001. Handbook of Public Water Systems. 2nd Edition. New
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Laine, J.M., J.G. Jacangelo, E.W. Cummings, K.E. Cams, and J. Mallevialle. 1993.
Influence of Bromide on Low Pressure Membrane Filtration for Controlling DBFs in
Surf ace Waters. Journal of American Water Works Association. 85(6): 87-99.
Malcom Pirnie, Inc. 1992. Arsenic Removal Pilot-Studies. Prepared for EPA Office of
Ground Water and Drinking Water.
Mallevialle, J.,, P.E. Odendaal, andM.R. Wiesner. 1996. Water Treatment Membrane
Processes. AwwaRF Report 90716. Project #826. Denver: AwwaRF.
Simultaneous Compliance Guidance Manual 7-20 March 2007
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-------
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Montgomery Watson Inc. 1998. Palm Beach County Water Utilities Department Water
Treatment Plant No. 3. Membrane Softening Facility Operations Manual Final Report.
pp. 4-19 to 4-20.
Panayides, N. 1999. Operational Procedures of a New 27 MGD Nanofiltration Membrane
Water Treatment Plant (WTP No. 9) in South Florida. Palm Beach County Water
Utilities Department.
Parson, F., P.R. Wood, and J. DeMarco. 1980. Bacteria associated with granular activated
carbon columns. In Proceedings ofAWWA Technology Conference, p.271-296. Denver:
AWWA.
Schippers, J.C., J.C. Kruithof, M.M. Nederlof, J.A.M.H. Hofman, and J. Taylor. 2004.
Integrated Membrane Systems. AwwaRF Report 90899. Project #264. Denver: AwwaRF.
U.S. Bureau of Reclamation. 1998. The Desalting and Water Treatment Membrane
Manual: A Guide to Membranes for Municipal Water Treatment. 2nd Edition. Technical
Service Center, Water Treatment Engineering and Research, Denver, CO.
USEPA. 200Ih. Low-Pressure Membrane Filtration for Pathogen Removal: Application,
Implementation, and Regulatory Issues. Office of Water. EPA 815-C-01-001.
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009. November, 2005.
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Forthcoming, http://www.epa.gov/safewater/disinfection/lt2/compliance.html
7.1.11 Riverbank Filtration
Gollnitz, W.D., J.L.Clancy, J. B. McEwen, and S. C. Garner. 2005. Riverbank Filtration
for IESWTR Compliance. Journal of American Water Works Association. 97(12):64-76.
Julich, W. and J. Schubert (editors). Proceedings of International Riverbank Filtration
Conference, Nov. 2-4, Duesseldorf. International Arbeitgemeinschaft der Wasserwerke
im Rheineinzugsgebiet, Amsterdam.
Ray, C. (editor). 2001. Riverbank Filtration: Understanding Contaminant
Biogeochemistry and Pathogen Removal. NATO Science Series IV. Earth and
Environmental Sciences, Vol. 14. Norwell: Kluwer Academic Publishers.
USEPA. 200Ih. Low-Pressure Membrane Filtration for Pathogen Removal: Application,
Implementation, and Regulatory Issues. Office of Water. EPA 815-C-01-001.
http://www.epa.gOv/OGWDW/disinfection/l t2/pdfs/report__lt2_membranefiltration. pdf
Wang, J., S. Hubbs, and R. Song. 2002. Evaluation of Riverbank Filtration as a Drinking
Water Treatment Process. AwwaRF Report 90922. Project #2622. Denver: AwwaRF.
Weiss, W.J., E.J. Bouwer, W.P. Ball, C.R. O'Melia, M.W. LeChevallier, H. Arora, and
T.F. Speth. 2003. Riverbank Filtration - fate of DBF presursors and selected
microorganisms. Journal of American Water Works Association. 95(10): 68-81.
Simultaneous Compliance Guidance Manual 7-21 March 2007
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7. References
7.1.12Chloramines
Arber, R., M.A. Speed, and F. Scully. 1985. Significant Findings Related to Formation of
Chlrinated Organics, in the Presence of Chloramines. In Water Chlormatron:
Environmental Impact and Health Effects, Vol. 7. Edited by R.L. Jolley, RJ. Bull, W.P.
Davis, S. Katz, M.H. Roberts, and V. A. Jacobs. Chelsea: Lewis Publishers.
AWWA. 2004b. Converting Distribution Systems from Chlorine to Chloramines. DVD.
Denver: AWWA.
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water
Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver:
AwwaRF.
Bonds, R.W. 2004. Effect of Chloramines on Ductile-Iron Pipe Gaskets of Various
Elastomer Compounds. Journal of American Water Works Association. 96(4): 153-160.
Boyd, G.R., K.M. Dewis, A.M. Sandvig, GJ. Kirmeyer, S.H. Reiber, and G.V. Korshin.
2006. Effect of Changing Disinfectants on Distribution System Lead and Copper Release,
Part 1—Literature Review. AwwaRF Report 91152. Project # 3107. Denver: AwwaRF.
Colbourne, J. 2001. Tools and Methods to Effectively Measure Customer Perceptions.
AwwaRF Report 90856. Project #466. Denver: AwwaRF.
Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in
Distribution Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Edwards, M., J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole
leaks in residential plumbing. Water Science and Technology. 49(2): 83-90.
Flannery, B., L.B. Gelling, DJ. Vugia, J.M. Weintraub, JJ. Salerno, and MJ. Conroy.
2006. Reducing Legionella colonization of water systems with monochloramine.
Emerging Infectious Diseases. 12(4): 588-596.
Gell, R. and J. Bromka. 2003. Successful Application of Chloramines to Manage
Disinfection By-Products. New York State Section AWWA. New York: O'Brien and
Gere.
Gianatasio, J.M. 1985. Experience at Tampa, Florida, Using Combined Chlorine to
Control THM Production. Presented at the North Carolina AWWA/WPLC Joint Technical
Conference. Charlotte, NC.
Harms, L.L. and C. Owen. 2004. A Guide for the Implementation and Use of
Chloramines. AwwaRF Report 91018F. Project #2847. Denver: AwwaRF.
Harrington, G.W., D.R. Noguera, C.C. Bone, A.I. Kandou, P.S. Oldenburg, J.M. Regan,
and D. Van Hoven. 2003. Ammonia from Chloramine Decay: Effects on Distribution
System Nitrification. AwwaRF Report 90949. Project #553. Denver: AwwaRF.
Hoehn, R.C., A.M. Dietrich, W.S., Farmer, M.P. Orr, R.G Lee, E.M. Aieta, D.W. Wood
III, and G. Gordon. 1990. Household Odors Associated with the Use of Chlorine Dioxide.
Journal of American Water Works Association. 82(4): 166-172.
Jacangelo, J.G., V.P. Olivieri, and K. Kawata. 1987. Mechanism of Inactivation of
Microorganisms by Combined Chlorine. Denver: AWWA.
Simultaneous Compliance Guidance Manual 7-22 March 2007
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Kirmeyer, G.J., M. Friedman, K. Martel, G. Thompson, A. Sandvig, J. Clement, and M.
Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality.
AwwaRF Report 90882. Project #2522. Denver: AwwaRF and AWWA.
Kirmeyer, G.J., M. LeChevallier, H. Barbeau, K. Martel, G. Thompson, L. Radder, W.
Klement, and A. Flores. 2004a. Optimizing Chloramine Treatment. AwwaRF Report
90993. Project #2760. Denver: AwwaRF and AWWA.
Kirmeyer, G.J., L.H. Odell, J. Jacangelo, A. Wilczak, and R. Wolfe. 1995. Nitrification
Occurrence and Control in Chloraminated Water Systems. AwwaRF Report 90669.
Project #710. Denver: AwwaRF.
Krasner, S.W., and S.E. Barrett. 1985. Aroma and Flavor Characteristics of Free Chlorine
and Chloramines. In Proceedings of Twelfth Annual AWWA Water Quality Technology
Conference. Denver: AWWA.
Krasner, S.W., S.R. Rajachandran, I.E. Cromwell III, D.M. Owen, and Z.K. Chowdhury.
2003. Case Studies of Modified Treatment Practices for Disinfection By-Product Control.
AwwaRF Report 90946F. Project #369. Denver: AwwaRF.
LeChevallier, M.W., C.D. Cawthorn, and R.G. Lee. 1988a. Factors Promoting Survival
of Bacteria in Chlorinated Water Supplies. Applied and Environmental Microbiology.
54(3): 649-654.
LeChevallier, M.W., C.D. Cawthorn, and R.G. Lee. 1988b. Inactivation of Biofilm
Bacteria. Applied and Environmental Microbiology. 54(10): 2492-2499.
LeChevallier, M.W., C.D. Lowry, and R.G. Lee. 1990. Disinfection of Biofilms in a
Model Distribution System. Journal of American Water Works Association. 82(7): 87-99.
Lytle, D.A. and M.R. Schock. 2005. The Formation of Pb(IV) Oxides in Chlorinated
Water. Journal of American Water Works Association. 97(11): 102.
Maas, R.P., J.C. Pitch, and A.M. Smith. 2005. Effects of Fluorides and Chloramines on
Lead Leaching from Leaded-Brass Surfaces. Asheville Environmental Quality Institute
Technical Report #04-137
McGuire, M.J., N.I. Lieu, and M.S. Pearthree. 1999. Using chlorite ion to control
nitrification. Journal of American Water Works Association. 91(10): 52-61.
McGuire, M.J., M.S. Pearthree, N.K. Blute, K.F. Arnold, and T. Hoogerwerf. 2006.
Nitrification Control by Chlorite Ion at Pilot Scale. Journal of American Water Works
Association. 98(1): 95-105.
Means, E.G., K.N. Scott, M.L. Lee, and R.W. Wolfe. 1986. Effects of Chlorine and
Ammonia Application Points on Bactericidal Efficiency. Journal of American Water
Works Association. 78(1): 62-69.
Olios, P.J., P.M. Huck, and R.M. Slawson. 2003. Factors Affecting Biofilm
Accumulation in Model Distribution Systems. Journal of American Water Works
Association. 94(1): 87-97.
Reiber, S. 1991. Corrosion Effects by Chloramines. Denver: AwwaRF.
Reiber, S. 1993. Chloramine Effects on Distribution System Materials. AwwaRF Report
90624. Project #508. Denver: AwwaRF.
Simultaneous Compliance Guidance Manual 7-23 March 2007
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7. References
Schock, M.R., 2001. Tetravalent Lead: A Hitherto Unrecognized Control of Tap Water
Lead Contamination. In Proceedings ofAWWA Water Quality Technology Conference.
Denver: AWWA.
Schock, M.R. 2005. Chapter 6: Distribution Systems as Reservoirs and Reactors for
Inorganic Contaminants. In Distribution System Water Quality Challenges in the 21st
Century. Denver: AWWA.
Schock, M.R. and R. Giani. 2004. Oxidant/Disinfectant Chemistry and Impacts on Lead
Corrosion. In Proceedings ofAWWA Water Quality Technology Conference. Denver:
AWWA.
Schock, M.R., I. Wagner, and R. Oliphant. 1996. The Corrosion and Solubility of Lead in
Drinking Water. In Internal Corrosion of Water Distribution Systems. 2nd edition.
AwwaRF and DVGW TZW Cooperative Research Report. AwwaRF Report 90508.
Project #725. Denver: AwwaRF.
Skadsen, J. 1993. Nitrification in a Distribution System. Journal of American Water
Works Association. 85(7): 95-103.
Speitel, G.E. Jr., P.G. Pope, M.R. Collins, and M. Martin-Doole. 2004. Disinfection By-
Product Formation and Control During Chloramination. AwwaRF Report 91040F.
Project #2677. Denver: AwwaRF.
Symons, J.M., G.E. Speitel, Jr., C. Hwang, S.W. Krasner, and S.E. Barrett. 1998. Factors
Affecting DBF Formation During Chloramination. AwwaRF Report 90728. Project #803.
Denver: AwwaRF.
Tokuno, S. 1999. Granulated Activated Carbon Filtration and Chloramine. Water
Engineering Management. 146(1): 16-21.
Uchida, M. and A. Okuwaki. 1999. Dissolution Behavior of Lead Plates in Aqueous
Nitrate Solutions. Corrosion Science. 41(10): 1977-1986.
USEPA. 1992a. Control of Biofilm Growth in Drinking Water Distribution Systems.
Office of Research and Development. EPA 625/R-92/001.
USEPA. 1992b. Lead and Copper Rule Guidance Manual, Vol. II: Corrosion Control
Treatment. Prepared by Malcolm Pirnie, Inc. & Black & Veatch. September 1992.
Valentine, R.L. 1998. Chloramine Decomposition in Distribution System and Model
Waters. AwwaRF Report 90721. Project #937. Denver: AwwaRF.
Vikesland, P.J., N.G. Love, K. Chandran, E.M. Fiss, R. Rebodos, A.E. Zaklikowski, F.A.
DiGiano, and B. Ferguson. 2006. Seasonal Chlorimation Practices and Impacts to
Chloraminating Utilties. Denver: AwwaRF.
Wilczak, A. L. Hoover, and H.H. Lai. 2003. Effects of Treatment Changes on
Chloramine Demand and Decay. Journal of American Water Works Association. 95(7):
94-107.
Wilczak, A., J.G. Jacangelo, J.P. Marcinko, L.H. Odell, G.J. Kirmeyer, and R.L. Wolfe.
1996. Occurrence of Nitrification in Chloraminated Distribution Systems. Journal of
American Water Works Association. 88(7): 74-85.
Simultaneous Compliance Guidance Manual 7-24 March 2007
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7. References
Wolfe, R.L, N.I. Lieu, G. Izagiurre, and E.G. Means. 1990. Ammonia-Oxidizing Bacteria
in a Chloraminated Distribution System: Seasonal Occurrence, Distribution, and
Disinfection Resistance. Applied and Environmental Microbiology. 56(2): 451-462.
Wolfe. R.L., E.G. Means, M.K. Davis, and S.E. Barrett. 1988. Biological Nitrification in
Covered Reservoirs Containing Chloraminated Water. Journal of American Water Works
Association. 80(9): 109-114.
7.1.13 Ozone
Angara, G., L. Cummings, W.R. Knocke, and G.C. Budd. 2004. Intermediate and Long-
Term Manganese Control Strategies During the Upgrade of the Little Falls Water
Treatment Plant. In Proceedings AWWA WQTC. Denver: AWWA.
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water
Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver:
AwwaRF.
AwwaRF and Compagnie Generate des Eaux. 1992. Ozone in Water Treatment:
Application and Engineering. AwwaRF Report. Project #421. Denver: AwwaRF.
Becker, W.C., O'Brien and Gere Engineers, C.R. O'Melia, and Department of Geography
and Environmental Engineering, The Johns Hopkins University. 1996. Optimizing
Ozonationfor Turbidity andOrganics (TOC) Removal by Coagulation and Filtration.
AwwaRF Report 90703. Project #934. Denver: AwwaRF.
Carlson, K.H. and G.L. Amy. 2001. Ozone and biofiltration optimization for multiple
objectives. Journal of American Water Works Association. 93(1): 88-98.
Colbourne, J. 2001. Tools and Methods to Effectively Measure Customer Perceptions.
AwwaRF Report 90856. Project #466. Denver: AwwaRF.
Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in
Distribution Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Escobar, 1C. and A.A. Randall. 2001. Case study: Ozonation and distribution system
biostability. Journal of American Water Works Association. 93(10): 77-89.
Gabelich, C.J., W.R. Knocke, B.M. Coffey, R. Johnston, H. Do, and A.A. Mofidi. 2005.
Manganese Desorption from filter media: experiences with biological filtration. AWWA
Annual Conference and Exposition. San Francisco: AWWA.
Galey, C., V. Mary-Dile, D. Gatel, G. Amy, and J. Cavard. 2001. Controlling bromate
formation. Journal of American Water Works Association. 93(8): 105-115.
Huck, P.M., B.M. Coffey, A. Amirtharajah, andE.J. Bouwer. 2000. Optimizing Filtration
in Biological Filters. AwwaRF Report 90793. Project #252. Denver: AwwaRF.
Kennedy, R.M. and M.E. Richardson. 2004. Ozone and Biofiltration, An Improved Water
Quality at Wilmington. PowerPoint Presentation.
Kirmeyer, G.J., M. Friedman, K. Mattel, G. Thompson, A. Sandvig, J. Clement, and M.
Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality.
AwwaRF Report 90882. Project #2522. Denver: AwwaRF and AWWA.
Simultaneous Compliance Guidance Manual 7-25 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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7. References
LeChevallier, M.W., W.C. Becker, P. Schorr, and R.G. Lee. 1992. Evaluating the
Performance of Biologically Active Rapid Sand Filters. Journal of American Water
Works Association. 84(4): 136.
McGuire, M., R. Hund, G. Burlingame, N. Graziano, and L. Sullivan. 2004. Water Utility
Self-Assessment for the Management of Aesthetic Issues. AwwaRF Report 90978F.
Project #2777. Denver: AwwaRF.
National Research Council. 2000. Identifying Future Drinking Water Contaminants.
Washington, D.C.: National Academy Press.
Price, M.L., CH2M Hill, in association with East Bay Municipal Utility District and City
of Tampa (FL) Water Department. 1994. Ozone and Biological Treatment for DBF
Control and Biological Stability. AwwaRF Report 90649. Project #504. Denver:
AwwaRF.
Reckhow, D.A. 1999. Control of Disinfection Byproduct Formation Using Ozone. In
Formation and Control of Disinfection By-Products in Drinking Water. Singer, P.C.
(editor), pp. 179-204. Denver: AWWA.
Reckhow, D.A. J.K. Edzwald, and I.E. Tobiason. 1993. Ozone as an Aid to Coagulation
and Filtration. AwwaRF Report 90643. Project #403. Denver: AwwaRF.
Stolarik, G. and J.D. Christie. 1997. A Decade of Ozonation in Los Angeles. In
Proceedings, IOA Pan American Group Annual Conference. Lake Tahoe, NV.
Urfer, D., P.M. Huck, S.D.J. Booth, and B.M. Coffey. 1997. Biological Filtration for
BOM and Particle Removal: A Critical Review. Journal of American Water Works
Association. 89(12): 83-98.
Urfer, D., P.M. Huck, G.A. Gagnon, D. Mutti, and F. Smith. 1999. Modeling enhanced
coagulation to improve ozone disinfection. Journal of American Water Works
Association. 91(3): 59-73.
USEPA. 1998a. Handbook: Optimizing Water Treatment Plant Performance Using the
Composite Correction Program. EPA 625/6-91/027.
USEPA. 1999a. Disinfection Profiling and Benchmarking Guidance Manual. EPA 815-
R-99-013.
USEPA. 1999J. M/DBP Stage 2 Federal Advisory Committee (FACA2) Distribution
Systems & ICR Data Analysis (12 months).
http://www.epa.gov/safewater/mdbp/st2oct99.html
Van der Kooij, D. 1997. Bacterial Nutrients and Biofilm Formation Potential within
Drinking Water Distribution Systems. In Proceedings, AWWA Water Quality Technology
Conference.
Wert, E.G., DJ. Rexing, and R.E. Zegers. 2005. Mangenese release from filter media
during the conversion to biological filtration. AWWA Annual Conference and Exposition.
San Francisco: AWWA.
Westerhoff, G.P., R. Song, G. Amy, and R. Minear. 1998b. NOM's role in bromine and
bromate formation during ozonation. Journal of American Water Works Association.
90(2): 82-94.
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7. References
Westerhoff, P., R.S. Summers, Z. Chowdhury, and S. Kommineni. 2005. Ozone-
EnhancedBiofiltrationfor Geosmin andMIB Removal. AwwaRF Report 91075. Project
#2775. Denver: AwwaRF.
Williams, M.D., B.M. Coffey, and S.W. Krasner, 2003. Evaluation of pH and Ammonia
for Controlling Bromate During Cryptosporidium Disinfection. Journal of American
Water Works Association. 95(10): 82-93.
Zhou, P. and J. Neemann. 2005. Use of Chlorine Dioxide and Ozone for Control of
Disinfection By-Products. AwwaRF Report 90981F. Project #2742. Denver: AwwaRF.
7.1.14 Ultraviolet Light
Ballester, N.A. and J.P. Malley, Jr. 2004. Sequential Disinfection of Adenovirus Type 2
with UV-Chlorine-Chloramine. Journal of American Water Works Association.
96(10):97-103.
Brodkorb, T. and D. Richards. 2004. UV disinfection design to avoid chlorine destruction
in high UVT waters. Presented at Ontario Water Works Association. Niagara Falls,
Ontario, Canada. May, 2004.
Bukhari, Z., T.M. Hargy, J.R. Bolton, B. Dussert, and J.L. Clancy. 1999. Medium-
Pressure UV for Oocyst Inactivation. Journal of American Water Works Association.
91(3): 86-94.
Clancy, J.L., Z. Bukhari, T.M. Hargy, J.R. Bolton, B.W. Dussert, and M.M. Marshall.
2000. Using UV to inactivate Cryptosporidium. Journal of American Water Works
Association. 92(9): 97-104.
Cotton, C.A., D.M. Owen, G.C. Cline, and T.P. Brodeur. 2001. UV disinfection costs for
inactivating Cryptosporidium. Journal of American Water Works Association. 93(6): 82-
94.
Cotton, C.A., L. Passantino, D.M. Owen, M. Bishop, M. Valade, W. Becker, R. Joshi, J.
Young, M. LeChevallier, and R. Hubel. 2005. Integrating UV Disinfection Into Existing
Water Treatment Plants. AwwaRF Report 91086. Project #2861. Denver: AwwaRF.
Crozes, G. 2001. Practical Aspects of UV Disinfection. AwwaRF Report 90875. Project
#2623. Denver: AwwaRF.
Gagnon, G.A., T.S. Dykstra, K.C. O'Leary, R.C. Andrews, C. Chauret and C. Volk.
2004. Impact of UV Disinfection on Biological Stability. AwwaRF Report 90999F.
Project #2723. Denver: AwwaRF.
Mackey, E.D., J. Malley, Jr., R.S. Gushing, M. Janex-Habibi, N. Picard, and J. Laine.
2001. Bridging Pilot-Scale Testing to Full-Scale Design of UV Disinfection Systems.
AwwaRF Report 90991. Project #2593. Denver: AwwaRF.
Malley, J. 2000. The state of the art in using UV disinfection for waters and wastewater
in North America. In Proceedings ofENVIRO 2000. April 9-13. Sydney: Australian
Water Association.
Simultaneous Compliance Guidance Manual 7-27 March 2007
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7. References
Malley, J., Jr., E.D. Mackey, R.S. Gushing, M. Janex-Habibi, N. Picard, and J. Lame.
2004. Inactivation of Pathogens with Innovative UV Technologies. AwwaRF Report
91024. Project #2593. Denver: AwwaRF.
Malley, J.P., Jr., B.A. Petri, G.V. Hunter, D. Moran, M. Nadeau, and J. Leach. 2002. Full
Scale Implimentation ofUVin Groundwater Disinfection Systems. AwwaRF Report
90860. Project #474. Denver: AwwaRF.
Mofidi, A.A., H. Baribeau, P.A. Rochelle, R. De Leon, B.M. Coffey, and J.F. Green.
2001. Disinfection of Cryptosporidium parvum with polychromatic UV light. Journal of
American Water Works Association. 93(6): 95-109.
National Research Council. 2000. Identifying Future Drinking Water Contaminants.
Washington, D.C.: National Academy Press.
NWRI and AwwaRF. 2000. Ultraviolet Disinfection Guidelines for Drinking Water and
Water Reuse. AwwaRF Report. Project #2674. Denver: AwwaRF.
Shaw, J.P., J.P. Malley Jr., and S. Willoughby. 2000. Effects of UV irradiation on organic
matter. Journal of American Water Works Association. 92(4): 157-167.
USEPA. 2006b. Ultraviolet Disinfection Guidance Manual for the Final Long Term 2
Enhanced Surface Water Treatment Rule. Office of Water. EPA 815-R-06-007.
November, 2006.
http://www.epa.gov/safewater/disinfecti on/1 t2/pdfs/guide_lt2_uvguidance.pdf
Wilczak, A. and H. Lai. 2006. Preliminary bench and pilot evaluation of UV-irradiation
for nitrification control. In Proceedings of the American Water Works Association Annual
Conference. June 11-16. San Antonio: AWWA.
7.1.15 Chlorine Dioxide
American Public Heath Association (APHA), AWWA, and Water Environment
Federation (WEF). 1998. Standard Methods for the Examination of Water and
Wastewater. 20th Edition. 220 pp. Washington, D.C.: APHA, AWWA, and WEF.
Andrews, R.C., Z. Alam, R. Hofmann, L. Lachuta, R. Cantwell, S. Andrews, E. Moffet,
G.A. Ganon, J. Rand, and C. Chauret. 2005. Impact of Chlorine Dioxide on
Transmission, Treatment, and Distribution System Performance. AwwaRF Report 91082.
Project #2843. Denver: AwwaRF.
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water
Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver:
AwwaRF.
Colbourne, J. 2001. Tools and Methods to Effectively Measure Customer Perceptions.
AwwaRF Report 90856. Project #466. Denver: AwwaRF.
Dietrich, A.M. andR.C. Hoehn. 1991. Taste-and-Odor Problems Associated with
Chlorine Dioxide. AwwaRF Report 90589. Project #405. Denver: AwwaRF.
Gallagher, D.L., R.C. Hoehn, and A.M. Dietrich. 1994. Sources, Occurrence, and
Control of Chlorine Dioxide By-Product Residuals in Drinking Water. AwwaRF Report
90656. Project #611. Denver: AwwaRF.
Simultaneous Compliance Guidance Manual 7-28 March 2007
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-------
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Gates, D. 1997. The Chlorine Dioxide Handbook. 177pp. Denver: AWWA.
Gell, R. and J. Bromka. 2003. Successful Application of Chloramines to Manage
Disinfection By-Products. New York State Section AWWA. New York: O'Brien and
Gere.
Gordon, G. 2001. Is all chlorine dioxide created equal? Journal of American Water
Works Association. 93(4): 163-174.
Hoehn, R.C. 1993. Chlorine Dioxide Use in Water Treatment. Key Issues Proceedings,
2nd Inter national Symposium, Chlorine Dioxide and Drinking Water Issues, pp. 1-14.
Houston, TX.
Hoehn, R.C., A.M. Dietrich, W.S., Farmer, M.P. Orr, R.G. Lee, E.M. Aieta, D.W. Wood
III, and G. Gordon. 1990. Household Odors Associated with the Use of Chlorine Dioxide.
Journal of American Water Works Association. 82(4): 166-172.
Kirmeyer, G.J., M. Friedman, K. Martel, G. Thompson, A. Sandvig, J. Clement, and M.
Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality.
AwwaRF Report 90882. Project #2522. Denver: AwwaRF and AWWA.
Krasner, S.W., S.R. Rajachandran, I.E. Cromwell III, D.M. Owen, and Z.K. Chowdhury.
2003. Case Studies of Modified Treatment Practices for Disinfection By-Product Control.
AwwaRF Report 90946F. Project #369. Denver: AwwaRF.
McGuire, M., R. Hund, G. Burlingame, N. Graziano, and L. Sullivan. 2004. Water Utility
Self-Assessment for the Management of Aesthetic Issues. AwwaRF Report 90978F.
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Volk, C.J., R. Hofmann, C. Chauret, G.A. Gagnon, G. Ranger, and R.C. Andrews. 2002b.
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ASTM D934-80. 2003. Standard Practices for Identification of Crystalline Compounds in
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ASTM Gl-81. 1981. Recommended Practise for Preparing, Cleaning and Evaluating
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-------
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-------
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-------
7. References
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7. References
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Simultaneous Compliance Guidance Manual 7-59 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
7. References
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Simultaneous Compliance Guidance Manual 7-60 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
7. References
November, 2006.
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Water.
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Water.
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USEPA. N.d.m. The LT2ESWTR State Implementation Guidance. Office of Water. EPA
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Simultaneous Compliance Guidance Manual 7-61 March 2007
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7. References
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7. References
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Appendix A
Summary of Pertinent Drinking Water Regulations
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Appendix A. Summary of Pertinent Drinking Water Regulations
Appendix A
Summary of Pertinent Drinking Water Regulations
This appendix contains fact sheets and quick reference guides for the major rules
discussed in this guidance manual. The fact sheets and quick reference guides are brief
summaries of the major requirements of the rules. More detailed information on rule
requirements and guidance can be found on EPA's Web site at http://www.epa.gov/safewater.
The following is a list of fact sheets and quick reference guides that are included in this appendix
and the order in which they appear:
Rule
Ground Water Rule (GWR)
Long Term 2 Enhanced Surface
Water Treatment Rule (LT2ESWTR)
Stage 2 Disinfectants and Disinfection
Byproducts Rule (Stage 2 DBPR)
Arsenic and Clarifications to
Compliance and New Source
Monitoring Rule
Lead and Copper Rule (LCR)
LCR Clarification of Requirements
for Collecting Samples and
Calculating Compliance
Total Coliform Rule (TCR)
Stage 1 Disinfectants and Disinfection
Byproducts Rule (Stage 1 D/DBPR)
Interim Enhanced Surface Water
Treatment Rule (IESWTR)
Long Term 1 Enhanced Surface
Water Treatment Rule (LT IESWTR)
Filter Backwash Recycling Rule
(FBRR)
Date of
Promulgation
November
2006
January 2006
January 2006
January 2001
June 1991
March 2004
June 1989
December
1998
December
1998
January 2002
June 2001
Contaminant of
Concern
Source Water Microbial
Pathogens
Source Water Microbial
Pathogens
Disinfection Byproducts
Arsenic
Lead and Copper
Lead and Copper
Distribution System
Microbial Pathogens
Disinfectants and
Disinfection Byproducts
Source Water Microbial
Pathogens
Source Water Microbial
Pathogens
Filter Backwash
(Microbial Pathogens)
Rule Summary
Information
Available from EPA
Fact Sheet
Fact Sheet
Fact Sheet
Quick Reference
Guide
Quick Reference
Guide
Fact Sheet
Quick Reference
Guide
Quick Reference
Guide
Quick Reference
Guide
Quick Reference
Guide
Quick Reference
Guide
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
A-l
March 2007
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Appendix A. Summary of Pertinent Drinking Water Regulations
This page intentionally left blank.
Simultaneous Compliance Guidance Manual A-2 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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United States
Environmental Protection
Agency
^^ ^^
Final Ground Water Rule
Summary
The Environmental Protection Agency (EPA) promulgated the final Ground Water Rule (GWR) in
October 2006 to reduce the risk of exposure to fecal contamination that may be present in public water
systems that use ground water sources. EPA proposed the GWR on May 10, 2000 (65 Federal Register
30194). The rule establishes a risk-targeted strategy to identify ground water systems that are at high
risk for fecal contamination. The GWR also specifies when corrective action (which may include
disinfection) is required to protect consumers who receive water from ground water systems from
bacteria and viruses.
Background
The 1 996 Amendments to the Safe Drinking Water Act required EPA to develop regulations that
require disinfection of ground water systems "as necessary" to protect the public health (section
Ground water occurrence studies and recent outbreak data show that pathogenic viruses and bacteria
can occur in public water systems that use ground water and that people may become ill due to
exposure to contaminated ground water.
Most cases of waterborne disease are characterized by gastrointestinal symptoms (e.g., diarrhea,
vomiting, etc.) that are frequently self-limiting in healthy individuals and rarely require medical
treatment. However, these same symptoms are much more serious and can be fatal for persons in
sensitive subpopulations (such as young children, the elderly, and persons with compromised immune
systems).
Viral and bacterial pathogens are present in human and animal feces, which can, in turn, contaminate
drinking water. Fecal contamination can reach ground water sources, including drinking water wells,
from failed septic systems, leaking sewer lines, and by passing through the soil and large cracks in the
ground. Fecal contamination from the surface may also get into a drinking water well along its casing or
through cracks if the well is not properly constructed, protected, or maintained.
EPA does not believe all ground water systems are fecally contaminated; data indicate that only a small
percentage of ground water systems are fecally contaminated. However, the severity of health impacts
and the number of people potentially exposed to microbial pathogens in ground water indicate that a
regulatory response is warranted.
About this Regulation
The GWR applies to more than 147, 000 public water systems that use ground water (as of 2003). The
rule also applies to any system that mixes surface and ground water if the ground water is added
directly to the distribution system and provided to consumers without treatment equivalent to surface
water treatment. In total, these systems provide drinking water to more than 100 million consumers.
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Final Requirements: The rule addresses risks through a risk-targeting approach that relies on four
major components:
1. Periodic sanitary surveys of ground water systems that require the evaluation of eight critical
elements and the identification of significant deficiencies (e.g., a well located near a leaking
septic system). States must complete the initial survey by December 31, 2012 for most
community water systems (CWSs) and by December 31, 2014 for CWSs with outstanding
performance and for all non-community water systems.
2. Source water monitoring to test for the presence of E. coli, enterococci, or coliphage in the
sample. There are two monitoring provisions:
-Triggered monitoring for systems that do not already provide treatment that achieves at
least 99.99 percent (4-log) inactivation or removal of viruses and that have a total coliform-
positive routine sample under Total Coliform Rule sampling in the distribution system.
-Assessment monitoring- As a complement to triggered monitoring, a State has the option
to require systems, at any time, to conduct source water assessment monitoring to help
identify high risk systems.
3. Corrective actions required for any system with a significant deficiency or source water fecal
contamination. The system must implement one or more of the following correction action
options:
-correct all significant deficiencies,
-eliminate the source of contamination,
-provide an alternate source of water, or
-provide treatment which reliably achieves 99.99 percent (4-log) inactivation or removal of
viruses.
4. Compliance monitoring to ensure that treatment technology installed to treat drinking water
reliably achieves at least 99.99 percent (4-log) inactivation or removal of viruses.
Environmental and Public Health Benefits
The GWR will reduce public health risk from contaminated ground water drinking water sources,
especially in high-risk or high-priority systems. The GWR is estimated to reduce the average number
of waterborne viral (rotovirus and echovirus) illnesses by nearly 42,000 illnesses each year from the
current baseline estimate of approximately 185,000 (a 23 percent reduction in total illnesses). In
addition, nonqualified benefits from the rule resulting in illness reduction from other viruses and
bacteria are expected to be significant.
Cost of the Regulation
The GWR will result in increased costs to public water systems and States. The mean annualized
present value national compliance costs of the final GWR are estimated to be approximately $62
million (using three percent discount rate). Public water systems will bear the majority of costs. The
annual household costs for community water systems (including those that do not add treatment) range
from $0.21 to $16.54. Annual household costs for the subset of systems that undertake corrective
actions range from $0.45 to $52.38, with 90 percent having household cost increases of no more than
$3.20.
How to Get Additional Information
For general information on the GWR, please contact the Safe Drinking Water Hotline, at (800) 426-
4791. The Safe Drinking Water Hotline is open Monday through Friday, excluding Federal holidays,
from 10 a.m. to 4 p.m., Eastern time. For copies of the Federal Register notice of the final regulation,
visit the EPA Safe water Web site, http://www.epa.gov/safewater/disinfection/gwr.
Office of Water (4607M) EPA815-F-06-003 October 2006 www.epa.gov/safewater
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Fact Sheet - Long Term 2 Enhanced Surface
Water Treatment Rule
Environmental Protection
Agency
In the past 30 years, the Safe Drinking Water Act (SDWA) has been highly effective in protecting
public health and has also evolved to respond to new and emerging threats to safe drinking water.
Disinfection of drinking water is one of the major public health advances in the 20th century. One
hundred years ago, typhoid and cholera epidemics were common through American cities;
disinfection was a major factor in reducing these epidemics.
In the past 15 years, we have learned that there are specific microbial pathogens, such as
Cryptosporidium, which can cause illness, and are highly resistant to traditional disinfection
practices. We also know that the disinfectants themselves can react with naturally-occurring
materials in the water to form byproducts, which may pose health risks.
Amendments to the SDWA in 1996 require EPA to develop rules to balance the risks between
microbial pathogens and disinfection byproducts (DBFs). The Stage 1 Disinfectants and
Disinfection Byproducts Rule and Interim Enhanced Surface Water Treatment Rule, promulgated in
December 1998, were the first phase in a rulemaking strategy required by Congress as part of the
1996 Amendments to the Safe Drinking Water Act.
The Long Term 2 Enhanced Surface Water Treatment Rule builds upon earlier rules to address
higher risk public water systems for protection measures beyond those required for existing
regulations.
The Long Term 2 Enhanced Surface Water Treatment Rule and the Stage 2 Disinfection Byproduct
Rule are the second phase of rules required by Congress. These rules strengthen protection against
microbial contaminants, especially Cryptosporidium, and at the same time, reduce potential health
risks of DBFs.
Questions and Answers
What is the LT2ESWTR?
The purpose of Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) is to reduce
illness linked with the contaminant Cryptosporidium and other pathogenic microorganisms in
drinking water. The LT2ESWTR will supplement existing regulations by targeting additional
Cryptosporidium treatment requirements to higher risk systems. This rule also contains provisions to
reduce risks from uncovered finished water reservoirs and provisions to ensure that systems maintain
microbial protection when they take steps to decrease the formation of disinfection byproducts that
result from chemical water treatment.
Current regulations require filtered water systems to reduce source water Cryptosporidium levels by
2-log (99 percent). Recent data on Cryptosporidium infectivity and occurrence indicate that this
treatment requirement is sufficient for most systems, but additional treatment is necessary for certain
-------
higher risk systems. These higher risk systems include filtered water systems with high levels of
Cryptosporidium in their water sources and all unfiltered water systems, which do not treat for
Cryptosporidium.
The LT2ESWTR is being promulgated simultaneously with the Stage 2 Disinfection Byproduct
Rule to address concerns about risk tradeoffs between pathogens and DBFs.
What are the health risks of Cryptosporidium?
Cryptosporidium is a significant concern in drinking water because it contaminates most surface
waters used as drinking water sources, it is resistant to chlorine and other disinfectants, and it has
caused waterborne disease outbreaks. Consuming water with Cryptosporidium can cause
gastrointestinal illness, which may be severe and sometimes fatal for people with weakened immune
systems (which may include infants, the elderly, and people who have AIDS).
Who must comply with this rule?
This regulation will apply to all public water systems that use surface water or ground water under
the direct influence of surface water.
What does the rule require?
Monitoring; Under the LT2ESWTR, systems will monitor their water sources to determine treatment
requirements. This monitoring includes an initial two years of monthly sampling for Cryptosporidium.
To reduce monitoring costs, small filtered water systems will first monitor for E. coli—a bacterium which
is less expensive to analyze than Cryptosporidium—and will monitor for Cryptosporidium only if their E.
coli results exceed specified concentration levels.
Monitoring starting dates are staggered by system size, with smaller systems beginning monitoring after
larger systems. Systems must conduct a second round of monitoring six years after completing the initial
round to determine if source water conditions have changed significantly. Systems may use (grandfather)
previously collected data in lieu of conducting new monitoring, and systems are not required to monitor
if they provide the maximum level of treatment required under the rule.
Cryjjtosjjoridium treatment; Filtered water systems will be classified in one of four treatment
categories (bins) based on their monitoring results. The majority of systems will be classified in the
lowest treatment bin, which carries no additional treatment requirements. Systems classified in
higher treatment bins must provide 90 to 99.7 percent (1.0 to 2.5-log) additional treatment for
Cryptosporidium. Systems will select from a wide range of treatment and management strategies in
the "microbial toolbox" to meet their additional treatment requirements. All unfiltered water systems
must provide at least 99 or 99.9 percent (2 or 3-log) inactivation of Cryptosporidium, depending on
the results of their monitoring. These Cryptosporidium treatment requirements reflect consensus
recommendations of the Stage 2 Microbial and Disinfection Byproducts Federal Advisory
Committee.
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Other requirements: Systems that store treated water in open reservoirs must either cover the
reservoir or treat the reservoir discharge to inactivate 4-log virus, 3-log Giardia lamblia, and 2-log
Cryptosporidium. These requirements are necessary to protect against the contamination of water
that occurs in open reservoirs. In addition, systems must review their current level of microbial
treatment before making a significant change in their disinfection practice. This review will assist
systems in maintaining protection against microbial pathogens as they take steps to reduce the
formation of disinfection byproducts under the Stage 2 Disinfection Byproducts Rule, which EPA is
finalizing along with the LT2ESWTR.
What are the benefits of the rule?
The LT2ESWTR will improve the control of Cryptosporidium and other microbiological pathogens
in drinking water water systems with the highest risk levels. EPA estimates that full compliance with
the LT2ESWTR will reduce the incidence of cryptosporidiosis - the gastrointestinal illness caused by
ingestion of Cryptosporidium - by 89,000 to 1,459,000 cases per year, with an associated reduction
of 20 to 314 premature deaths. The monetized benefits associated with these reductions ranges from
$253 million to $1.445 billion per year. The additional Cryptosporidium treatment requirements of
the LT2ESWTR will also reduce exposure to other microbial pathogens, such as Giardia, that co-
occur with Cryptosporidium. Additional protection from microbial pathogens will come from
provisions in this rule for reviewing disinfection practices and for covering or treating uncovered
finished water reservoirs, though EPA has not quantified these benefits.
What are the costs of the rule?
The LT2ESWTR will result in increased costs to public water systems and states. The average
annualized present value costs of the LT2ESWTR are estimated to range from $92 to $133 million
(using a three percent discount rate). Public water systems will bear approximately 99 percent of this
total cost, with states incurring the remaining 1 percent. The average annual household cost is
estimated to be $1.67 to $2.59 per year, with 96 to 98 percent of households experiencing annual
costs of less than $12 per year.
What technical information mil be available on the rule?
The following guidance documents will be available:
• Source Water Monitoring Guidance
• Microbial Laboratory Guidance
• Small Entity Compliance Guidance
• Microbial Toolbox Guidance Manual
• Ultraviolet Disinfection Guidance Manual
• Membrane Filtration Guidance Manual
• Simultaneous Compliance Guidance Manual
• Low-pressure Membrane Filtration for Pathogen Removal: Application, Implementation,
and Regulatory Issues
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Where can I find more information about this notice and the LT2ESWTR?
For general information on the LT2ESWTR, contact the Safe Drinking Water Hotline at (800)
426-4791. The Safe Drinking Water Hotline is open Monday through Friday, excluding legal
holidays, from 10:00 a.m. to 4:00 p.m., Eastern time. For copies of the Federal Register notice of
the regulation or technical fact sheets, visit the EPA Safewater website at
http://www.epa.gov/safewater/disinfection/lt2. For technical inquiries, email
stage2mdbp@epa.gov.
Office of Water (4607M) EPA 815-F-05-009 December 2005 www.epa.gov/safewater
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United States
Environmental Protection
Agency
Fact Sheet: Stage 2 Disinfectants and
Disinfection Byproducts Rule
In the past 30 years, the Safe Drinking Water Act (SDWA) has been highly effective in
protecting public health and has also evolved to respond to new and emerging threats to safe
drinking water. Disinfection of drinking water is one of the major public health advances in the
20th century. One hundred years ago, typhoid and cholera epidemics were common through
American cities; disinfection was a major factor in reducing these epidemics.
However, the disinfectants themselves can react with naturally-occurring materials in the water
to form byproducts, which may pose health risks. In addition, in the past 10 years, we have
learned that there are specific microbial pathogens, such as Cryptosporidium, which can cause
illness, and are highly resistant to traditional disinfection practices.
Amendments to the SDWA in 1996 require EPA to develop rules to balance the risks between
microbial pathogens and disinfection byproducts (DBFs). The Stage 1 Disinfectants and
Disinfection Byproducts Rule and Interim Enhanced Surface Water Treatment Rule,
promulgated in December 1998, were the first phase in a rulemaking strategy required by
Congress as part of the 1996 Amendments to the Safe Drinking Water Act.
The Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBPR) builds upon the
Stage 1 DBPR to address higher risk public water systems for protection measures beyond those
required for existing regulations.
The Stage 2 DBPR and the Long Term 2 Enhanced Surface Water Treatment Rule are the second
phase of rules required by Congress. These rules strengthen protection against microbial
contaminants, especially Cryptosporidium, and at the same time, reduce potential health risks of
DBFs.
Questions and Answers
What is the Stage 2 DBPR?
The Stage 2 Disinfection Byproducts Rule will reduce potential cancer and reproductive and
developmental health risks from disinfection byproducts (DBFs) in drinking water, which form
when disinfectants are used to control microbial pathogens. Over 260 million individuals are
exposed to DBFs.
This final rule strengthens public health protection for customers by tightening compliance
monitoring requirements for two groups of DBFs, trihalomethanes (TTHM) and haloacetic acids
(HAAS). The rule targets systems with the greatest risk and builds incrementally on existing
rules. This regulation will reduce DBF exposure and related potential health risks and provide
more equitable public health protection.
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The Stage 2 DBPR is being promulgated simultaneously with the Long Term 2 Enhanced
Surface Water Treatment Rule to address concerns about risk tradeoffs between pathogens and
DBFs.
What does the rule require?
Under the Stage 2 DBPR, systems will conduct an evaluation of their distribution systems,
known as an Initial Distribution System Evaluation (IDSE), to identify the locations with high
disinfection byproduct concentrations. These locations will then be used by the systems as the
sampling sites for Stage 2 DBPR compliance monitoring.
Compliance with the maximum contaminant levels for two groups of disinfection byproducts
(TTHM and HAAS) will be calculated for each monitoring location in the distribution system.
This approach, referred to as the locational running annual average (LRAA), differs from current
requirements, which determine compliance by calculating the running annual average of samples
from all monitoring locations across the system.
The Stage 2 DBPR also requires each system to determine if they have exceeded an operational
evaluation level, which is identified using their compliance monitoring results. The operational
evaluation level provides an early warning of possible future MCL violations, which allows the
system to take proactive steps to remain in compliance. A system that exceeds an operational
evaluation level is required to review their operational practices and submit a report to their state
that identifies actions that may be taken to mitigate future high DBP levels, particularly those
that may jeopardize their compliance with the DBP MCLs.
Who must comply with the rule?
Entities potentially regulated by the Stage 2 DBPR are community and nontransient
noncommunity water systems that produce and/or deliver water that is treated with a primary or
residual disinfectant other than ultraviolet light.
A community water system (CWS) is a public water system that serves year-round residents of a
community, subdivision, or mobile home park that has at least 15 service connections or an
average of at least 25 residents.
A nontransient noncommunity water system (NTNCWS) is a water system that serves at least 25
of the same people more than six months of the year, but not as primary residence, such as
schools, businesses, and day care facilities.
What are disinfection byproducts (DBFs)?
Disinfectants are an essential element of drinking water treatment because of the barrier they
provide against waterborne disease-causing microorganisms. Disinfection byproducts (DBFs)
form when disinfectants used to treat drinking water react with naturally occurring materials in
the water (e.g., decomposing plant material).
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Total trihalomethanes (TTHM - chloroform, bromoform, bromodichloromethane, and
dibromochloromethane) and haloacetic acids (HAAS - monochloro-, dichloro-, trichloro-,
monobromo-, dibromo-) are widely occurring classes of DBFs formed during disinfection with
chlorine and chloramine. The amount of trihalomethanes and haloacetic acids in drinking water
can change from day to day, depending on the season, water temperature, amount of disinfectant
added, the amount of plant material in the water, and a variety of other factors.
Are THMs andHAAs the only disinfection byproducts?
No. The four THMs (TTHM) and five HAAs (HAAS) measured and regulated in the Stage 2
DBPR act as indicators for DBF occurrence. There are many other known DBFs, in addition to
the possibility of unidentified DBFs present in disinfected water. THMs and HAAs typically
occur at higher levels than other known and unknown DBFs. The presence of TTHM and HAAS
is representative of the occurrence of many other chlorination DBFs; thus, a reduction in the
TTHM and HAAS generally indicates a reduction of DBFs from chlorination.
What are the costs and benefits of the rule?
Quantified benefits estimates for the Stage 2 DBPR are based on reductions in fatal and non-fatal
bladder cancer cases. EPA has projected that the rule will prevent approximately 280 bladder
cancer cases per year. Of these cases, 26% are estimated to be fatal. Based on bladder cancer
alone, the rule is estimated to provide annualized monetized benefit of $763 million to $1.5
billion.
The rule applies to approximately 75,000 systems; a small subset of these (about 4%) will be
required to make treatment changes. The mean cost of the rule is $79 million annually. Annual
household cost increases in the subset of plants adding treatment are estimated at an average of
$5.53, with 95 percent paying less than $22.40.
What are the compliance deadlines?
Compliance deadlines are based on the sizes of the public water systems (PWSs). Wholesale
and consecutive systems of any size must comply with the requirements of the Stage 2 DBPR on
the same schedule as required for the largest system in the combined distribution system (defined
as the interconnected distribution system consisting of wholesale systems and consecutive
systems that receive finished water). Compliance activities are outlined in the following table.
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PUBLIC WATER
SYSTEMS
CWSsandNTNCWSs
serving at least 100,000
CWSsandNTNCWSs
serving 50,000 - 99,999
CWSsandNTNCWSs
serving 10,000 - 49,999
CWSs serving fewer
than 10,000
NTNCWSs serving
fewer than 10,000
ACTIONS
Submit IDSE
monitoring plan, system
specific study plan, or
40/30 certification
October 1, 2006
April 1, 2007
October 1, 2007
April 1, 2008
NA
Complete an
initial distribution
system evaluation
(IDSE)
September 30,
2008
March 3 1,2009
September 30,
2009
March 3 1,2010
NA
Submit IDSE
Report
January 1,2009
July 1, 2009
January 1,2010
July 1, 2010
NA
Begin subpart
V (Stage 2)
compliance
monitoring
April 1, 2012
October 1,2012
October 1,2013
October 1,2013
October 1, 2013
* States may grant up to an additional two years for systems making capital improvements.
What technical information mil be available on the rule?
The following Guidance Documents will be available:
• Initial Distribution System Evaluation (IDSE) Guidance Manual
• Operational Evaluation Guidance Manual
• Consecutive Systems Guidance Manual
• Small Systems (SBREFA) Guidance Manual
• Simultaneous Compliance Guidance Manual
Where can I find more information about this notice and the Stage 2 DBPR?
For general information on the rule, please visit the EPA Safewater website at
http://www.epa.gov/safewater/disinfection/stage2 or contact the Safe Drinking Water Hotline at
1-800-426-4791. The Safe Drinking Water Hotline is open Monday through Friday, excluding
legal holidays, from 10:00 a.m. to 4:00 p.m., Eastern Time. For technical inquiries, email
stage2mdbp(S)/epa. gov.
Office of Water (4607M) EPA 815-F-05-003 December 2005 www.epa.gov/safewater
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vvEPA
United States
Environmental Protection
Agency
Office of Water
(4606)
EPA 816-F-01-004
January 2001
Arsenic and Clarifications to Compliance and New
Source Monitoring Rule: A Quick Reference Guide
Overview of the Rule
\
Title
Purpose
General
Description
Utilities
Covered
Arsenic and Clarifications to Compliance and New Source Monitoring Rule
66 FR 6976 (January 22, 2001)
To improve public health by reducing exposure to arsenic in drinking water.
Changes the arsenic MCL from 50 |jg/L to 10 \JtglL; Sets arsenic MCLG at 0; Requires
monitoring for new systems and new drinking water sources; Clarifies the procedures for
determining compliance with the MCLs for lOCs, SOCs, and VOCs.
All community water systems (CWSs) and nontransient, noncommunity water systems
(NTNCWSs) must comply with the arsenic requirements. EPA estimates that 3,024 CWSs
and 1,080 NTNCWSs will have to install treatment to comply with the revised MCL.
Public Health Benefits
Implementation of the Arsenic
Rule will result in ...
• Avoidance of 16 to 26 non-fatal bladder and lung cancers per year.
• Avoidance of 21 to 30 fatal bladder and lung cancers per year.
• Reduction in the frequency of non-carcinogenic diseases.
Critical Deadlines & Requirements
Consumer Confidence Report Requirements *
Report Due
July 1, 2001
July 1, 2002
and beyond
July 1, 2002 -
Julyl, 2006
July 1, 2007
and beyond
Report Requirements
For the report covering calendar year 2000, systems that detect arsenic between 25 pg/L
and 50 [iglL must include an educational statement in the consumer confidence reports
(CCRs).
For reports covering calendar years 2001 and beyond, systems that detect arsenic
between 5 |jg/L and 10 |jg/L must include an educational statement in the CCRs.
For reports covering calendar years 2001 to 2005, systems that detect arsenic between
10 |jg/L and 50 [icjIL must include a health effects statement in their CCRs.
For reports covering calendar year 2006 and beyond, systems that are in violation of the
arsenic MLC (10 pg/L) must include a health effects statement in their CCRs.
For Drinking Water Systems
Jan. 22, 2004
Jan. 1,2005
Jan. 23, 2006
Dec. 31, 2006
Dec. 31, 2007
All NEW systems/sources must collect initial monitoring samples for all lOCs, SOCs, and
VOCs within a period and frequency determined by the State.
When allowed by the State, systems may grandfather data collected after this date.
The new arsenic MCL of 10 pg/L becomes effective. All systems must begin monitoring or
when allowed by the State, submit data that meets grandfathering requirements.
Surface water systems must complete initial monitoring or have a State approved waiver.
Ground water systems must complete initial monitoring or have a State approved waiver.
For States
Spring 2001
Jan. 22, 2003
Jan. 22, 2005
EPA meets and works with States to explain new rules and requirements and to initiate
adoption and implementation activities.
State primacy revision applications due.
State primacy revision applications due from States that received 2-year extensions.
* For required educational and health effects statements, please see 40 CFR 141.154.
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Compliance Determination (lOCs, VOCs, and SOCs)
1. Calculate compliance based on a running annual average at each sampling point.
2. Systems will not be in violation until 1 year of quarterly samples have been collected (unless
fewer samples would cause the running annual average to be exceeded.)
3. If a system does not collect all required samples, compliance will be based on the running
annual average of the samples collected.
onitoring Requirements tor Total Arsenic
Initial Monitoring
One sample after the effective date of the MCL (January 23, 2006). Surface water systems must take
annual samples. Ground water systems must take one sample between 2005 and 2007.
Reduced Monitoring
If the initial monitoring result for
arsenic is less than the MCL . ..
Ground water systems must collect one sample every 3 years.
Surface water systems must collect annual samples.
Increased Monitoring
A system with a sampling point result above the MCL must collect quarterly samples at that sampling
point, until the system is reliably and consistently below the MCL.
(1> All samples must be collected at each entry point to the distribution system, unless otherwise specified by the
State.
For additional
information on the
Arsenic Rule
Call the Safe Drinking Water
Hotline at 1-800-426-4791;
visit the EPA Web site at
www.epa.gov/safewater; or
contact your State drinking
water representative. EPA
will provide arsenic training
over the next year.
Applicability of the Standardized Monitoring Framework to Arsenic
FIRST COMPLIANCE CYCLE
3rd Compliance Period
1999 2000 2001
SECOND COMPLIANCE CYCLE
Below Trigger Level
GROUND WATER
No Waiver
Waiver"
SURFACE WATER
No Waiver I • I I • I
Waiver"
Key
• One sampling event.
1st Compliance Period
2002 2003 2004
2nd Compliance Period
2005 2006 2007
3rd Compliance Period
2008 2009 2010
J L
LT] LT] LT] LT]
Effective Date of Revised MCL
Jan. 23, 2006
Surface Water Systems:
Initial Samples Collected by
Dec. 31,2006
Ground Water Systems:
Initial Samples Collected by
Dec. 31,2007
LT] LT] LT]
'Waivers are not permitted under the current arsenic requirements. States may issue 9 year monitoring waivers under the
revised final arsenic rule. To be eligible for a waiver, surface water systems must have monitored annually for at least 3 years.
Ground water systems must conduct a minimum of 3 rounds of monitoring with detection limits below 10 ug/L.
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&ER&
United States
Environmental Protection
Agency
'
1The June 1991 LCR was
revised with the following
Technical Amendments:
56 FR 32112, July 15, 1991;
57 FR 28785, June 29, 1992;
59 FR 33860, June 30, 1994;
and the LCR Minor Revisions
65 FR 1950, January 12,2000.
Lead and Copper Rule: A Quick Reference Guide
Overvie
Title
Purpose
General
Description
Utilities
Covered
'W of the Rule
Lead and Copper Rule (LCR)1, 56 FR 26460 - 26564, June 7, 1991
Protect public health by minimizing lead (Pb) and copper (Cu) levels in drinking
water, primarily by reducing water corrosivity. Pb and Cu enter drinking water
mainly from corrosion of Pb and Cu containing plumbing materials.
Establishes action level (AL) of 0.015 mg/L for Pb and 1.3 mg/L for Cu based on
90th percentile level of tap water samples. An AL exceedance is not a violation but
can trigger other requirements that include water quality parameter (WQP)
monitoring, corrosion control treatment (CCT), source water monitoring/treatment,
public education, and lead service line replacement (LSLR).
All community water systems (CWSs) and non-transient, non-community water
systems (NTNCWSs) are subject to the LCR requirements.
Public Health Benefits
Implementation
of the LCR has
resulted in ..
Reduction in risk of exposure to Pb that can cause damage to brain, red
blood cells, and kidneys, especially for young children and pregnant women.
Reduction in risk of exposure to Cu that can cause stomach and
intestinal distress, liver or kidney damage, and complications of Wilson's
disease in genetically predisposed people.
Lead
and Copper Tap Sampling Requirements
> First draw samples must be collected by all CWSs & NTNCWSs at cold water taps in
homes/buildings that are at high risk of Pb/Cu contamination as identified in 40 CFR 141.86(a).
>• Number of sample sites is based on system size (see Table 1).
> Systems must conduct monitoring every 6 months unless they qualify for reduced monitoring
(see Table 2).
Size
Category
Large
Medium
Small
Table 1: Pb and Cu Tap and WQP Tap Monitoring
System Size
>100K
50,001 -100K
10,001 -50K
3,301 - 10K
501 - 3,300
101 -500
< 100
Number of Pb/Cu Tap Sample Sites
Standard
100
60
60
40
20
10
5
Reduced
50
30
30
20
10
5
5
Number of WQP Tap Sampling Sites
Standard
25
10
10
3
2
1
1
Table 2: Criteria for Reduced Pb/Cu Tap Monitoring3
Can Monitor . . .
Annually
Triennially
Once every 9
years
Reduced
10
7
7
3
2
1
1
If the System . . .
1. Serves < 50,000 and is < both ALs for 2 consecutive 6-month monitoring periods; or
2. Meets Optimal Water Quality Parameter (OWQP) specifications for 2 consecutive 6-
month monitoring periods.
1. Serves < 50,000 and is < both ALs for 3 consecutive years of monitoring; or
2. Meets OWQP specifications for 3 consecutive years of monitoring;
or
3. Has 90th percentile Pb levels < 0.005 mg/L & 90th percentile Cu level < 0.65 mg/L for
2 consecutive 6-month periods (i.e, accelerated reduced Pb/Cu tap monitoring), or
4. Meets the 40 CFR 141.81(b)(3) criteria.
Serves < 3,300 and meets monitoring waiver criteria found at 40 CFR
141.86(g).
a Samples are collected at reduced number of sites (see Table 1 above).
Treatment Technique and Sampling Requirements
CORROSION CONTROL TREATMENT INSTALLATION: All large systems (except systems that
meet the requirements of 40 CFR 141.81(b)(2) or (3)) must install CCT. Medium and small systems
that exceed either AL must install CCT.
WATER QUALITY PARAMETER MONITORING: All large systems are required to do WQP
monitoring. Medium and small systems that exceed either AL are required to do WQP
monitoring.
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Treatment Techniqu
the AL is Exceeded
For additional information on
the LCR, call the Safe Drinking
Water Hotline at 1-800-426-
4791; visit the EPA web site at
www.epa.gov/safewater/lcrmr/
implement.html; or contact your
State drinking water
representative.
O Water Quality Parameter (WQP) Monitoring
> All systems serving > 50,000 people, and those systems serving < 50,000 people if 90th percentile tap
level > either AL, must take WQP samples during the same monitoring periods as Pb/Cu tap sample.
> Used to determine water corrosivity, and if needed, to help identify type of CCTto be installed and how
CCT should be operated (i.e., establishes OWQP levels).
> WQPs include: pH, alkalinity, calcium, conductivity (initial WQP monitoring only), orthophosphate (if
phosphate-based inhibitor is used); silica (if silicate-based inhibitor is used), and temperature (initial
WQP monitoring only).
> Samples are collected within distribution system (i.e., WQP tap samples), with number of sites based
on system size (see Table 1), and at each entry point to distribution system (EPTDS).
t Systems installing CCT, must conduct follow-up monitoring for 2 consecutive 6-month periods - WQP
tap monitoring is conducted semi-annually; EPTDS monitoring increases to every two weeks.
> After follow-up monitoring, State sets ranges of values for the OWQPs.
> Reduced WQP tap monitoring is available for systems in compliance with OWQPs; Reduced
monitoring does not apply to EPTDS monitoring.
t For systems < 50,000, WQP monitoring is not required whenever 90th percentile tap levels are < both
ALs.
6 Public Education (PE)
> Only required if Pb AL is exceeded (no public education is required if only Cu AL exceeded).
t Informs Public Water System's (PWS) customers about health effects, sources, and what can be done
to reduce exposure.
> Includes billing inserts sent directly to customers, pamphlets or brochures distributed to hospitals &
other locations that provide services to pregnant woman & children, and for some CWSs, newspaper
notices and public service announcements (PSAs) submitted to TV/radio stations.
t System must begin delivering materials within 60 days of Pb AL exceedance and continue every 6
months for PSAs and annually for all other forms of delivery for as long as it exceeds Pb AL.
> Different delivery methods and mandatory language for CWSs & NTNCWSs.
> Can discontinue delivery whenever < Pb AL; but must recommence if Pb AL subsequently exceeded.
> PE requirements are in addition to the Public Notification required in 40 CFR Subpart Q.
© Source Water Monitoring and Treatment
> All systems that exceed Pb or Cu AL must collect source water samples to determine contribution from
source water to total tap water Pb/Cu levels and make a source water treatment (SOWT)
recommendation within 6 months of the exceedance.
> One set of samples at each EPTDS is due within 6 months of first AL exceedance.
> If State requires SOWT; system has 24 months to install SOWT.
> After follow-up Pb/Cu tap and EPTDS monitoring, State sets maximum permissible levels for Pb & Cu
in source.
O Corrosion Control Treatment
> Required for all large systems (except systems that meet the requirements of 40 CFR 141.81(b)(2) or
(b)(3)) and medium/small systems that exceed either AL. The system shall recommend optimal CCT
within 6 months.
> Corrosion control study required for large systems.
> If State requires study for medium or small systems, it must be completed within 18 months.
> Once State determines type of CCT to be installed, PWS has 24 months to install CCT
> Systems installing CCT must conduct 2 consecutive 6-months of follow-up monitoring.
> After follow-up Pb/Cu tap & WQP monitoring, State sets OWQPs.
> Small & medium systems can stop CCT steps if < both ALs for 2 consecutive 6-month monitoring
periods.
If the system continues to exceed the AL after installing CCT and/or SOWT...
0 Lead Service Line (LSL) Monitoring
> Two types of sampling associated with LSL replacement (LSLR):
- Optional - Monitoring from LSL to determine need to replace line. If all Pb samples from line
< 0.015 mg/Lthen LSL does not need to be replaced and counts as replaced line.
- Required - Monitoring if entire LSL is not replaced to determine impact from "partial" LSLR.
Sample is collected that is representative of water in service line that is partially replaced.
> Monitoring only applies to system subject to LSLR.
0 Lead Service Line Replacement
> System must replace LSLs that contribute more than 0.015 mg/Lto tap water levels.
> Must replace 7% of LSL per year; State can require accelerated schedule.
> If only a portion of a LSL is replaced, PWS must:
- Notify customers at least 45 days prior to replacement about the potential for increased Pb levels;
- Collect sample within 72 hours of replacement and mail/post results within 3 days of receipt of
results.
> Systems can discontinue LSLR whenever < Pb AL in tap water for 2 consecutive monitoring periods.
Office of Water (4606)
EPA816-F-04-009
www.epa.gov/safewater
March 2004
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K
"2-
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
NOV 23 2004
OFFICE OF
WATER
MEMORANDUM
SUBJECT: Lead and Copper Rule - Clarification of Requirements for Collecting Samples and
Calculating Compliance
FROM: Benjamin H. Grumbles
Acting Assistant Administrator
TO: Regional Administrators
Water Division Directors
Regions I-X
This memo reiterates and clarifies elements of the Lead and Copper Rule (LCR)
associated with the collection and management of lead and copper samples and the calculation of
the lead 90th percentile for compliance. Over the past several months, Headquarters has been
conducting a national review of implementation of the LCR. This review consists of both data
analysis and feedback from expert panels on aspects of the rule. Headquarters is continuing its
review, and will be making a determination in early 2005 on specific areas of the rule that may
require changes in regulation or need clarification through guidance or training.
One area identified for additional guidance is the management of lead and copper samples
and the calculation of the lead 90th percentile. Because the need for additional guidance was
identified in both Headquarters' data review and the expert panels, Headquarters is addressing
this area prior to the final determination on rule and guidance changes. This guidance reflects the
requirements of the LCR as it is currently written. These issues may be revisited if EPA makes a
determination that changes should be made to the LCR.
1) What samples are used to calculate the 90th percentile?
We have received several questions regarding what tap samples should be used to
calculate the 90th percentile for lead, specifically, where utilities collect samples beyond the
minimum number required by the regulations. EPA regulations require water systems to develop
a targeted sampling pool, focused on those sites with the greatest risk of lead leaching. All
compliance samples used to determine the 90th percentile must come from that sampling pool.
All sample results from a system's sampling pool during the monitoring period must be included
Internet Address (URL) • http://www.epa.gov
Recycled/Recyclable • Printed with Vegetable Oil Based Inks on Recycled Paper (Minimum 30% Postconsumer)
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in the 90th percentile calculation, even if this includes more samples than the required minimum
number needed for compliance. [40 CFR 141.86(e)] For example, consider a situation where a
system sends out sample kits to 150 households to ensure that it will have a sufficient number of
samples to meet its required 100 samples for compliance. If the system receives sample results
from 140 households, it would use the results of the 140 samples in calculating the 90th
percentile.
In some cases, a utility may choose to
take a confirmation sample to verify a high or
low concentration. It is entirely possible for
the concentration of a confirmation sample to
be significantly higher or lower than the
concentration of the original sample.
However, where confirmation samples are
taken, the results of the original and
confirmation sample must be used in
calculating the 90th percentile. The LCR does
not allow substitution of results with
"confirmation" samples, nor does it allow the
averaging of initial and confirmation samples
as a single sampling result. While we support
re-sampling at a home with high lead levels,
all sample results from the sampling pool collected within the monitoring period must be
included in the calculation.
Inclusion of samples in
90th Percentile Calculations
40 CFR 141.86(e) "The results of any additional
monitoring conducted in addition to the minimum
requirements of this section shall be considered by the
system and the state in making any determinations
(i.e.; calculating the 90th percentile lead or copper
level) under this subpart."
40 CFR 141.80(c)(3)(i) "The results of all lead and
copper samples taken during a monitoring period shall
be placed in ascending order from the sample with the
lowest concentration to the sample with the highest
concentration...." [emphasis added]
2) What should utilities do with sample results from customer-requested sampling
programs?
EPA regulations require water systems to develop a targeted sampling pool, focused on
those sites with the greatest risk of lead leaching. All compliance samples used to determine the
90th percentile must come from that sampling pool. [40 CFR 141.80(c)(l)] ("Samples collected at
sites not meeting the targeting criteria may not be used in calculating the 90th percentile lead and
copper levels." 56 Fed Reg. 26518 (June 7, 1991)). Maintaining a consistent set of compliance
sample sites provides the system with a baseline against which to measure the 90th percentile
over time. If a system designates sites which were not sampled during previous monitoring
periods, it must notify the state and include an explanation of why the sampling sites have
changed. [40 CFR 141.90(a)(l)(v) and 141.90(h)(2)]
In addition to compliance sampling, many water systems have additional programs to test
for lead in drinking water at the request of homeowners. Customer-requested samples that are
not collected as part of the system's regular compliance sampling pool may or may not meet the
sample site selection criteria, and the system may not have sufficient information to determine
whether they do or not. Including results from samples that do not meet the criteria could
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inappropriately reduce the 90th percentile value. Therefore, samples collected under these
programs should not be used to calculate the 90th percentile, except in cases where the system is
reasonably able to determine that the site selection criteria for compliance sampling are satisfied.
However, even though these customer-requested samples are not used for the 90th
percentile calculation, the sample results must still be provided to the state. [40 CFR 141.90(g)]
If a significant number of customer-requested samples are above the lead action level, the state
should re-evaluate the corrosion control used by the system and the composition of the
compliance sampling pool. Further, where any results are above the action level, we strongly
urge systems to follow up with the affected customers to provide them with information on ways
to reduce their risk of exposure to elevated lead levels in drinking water.
3) What should states do with samples taken outside of the sampling compliance
period?
The regulations require that systems on reduced monitoring collect samples during the
period between June and September, unless the state has approved an alternate period. [40 CFR
141.86(d)(4)(iv)] Only those samples collected during the compliance monitoring period may be
included in the 90th percentile calculation. [40 CFR 141.80(c)(3)]
An exception to this is where a state invalidates a sample and the system must collect a
replacement sample in order to have a sufficient number with which to calculate compliance.
The system must collect its replacement sample within 20 days of the invalidation. Even if the
date of collection occurs after the closure of the monitoring period (but within 20 days of the
invalidation), the results must be included in the 90th percentile calculation. [40 CFR
141.86(f)(4)]
Although samples collected outside the sampling compliance period should not be used
in the compliance calculation, they must still be provided to the state [40 CFR 141.90(g)], as is
the case with customer-requested samples.
4) What should states do to calculate compliance if the minimum number of samples
are not collected?
As noted in guidance released earlier this year1, states must calculate the 90th percentile
even if the minimum number of samples are not collected. The LCR states that the 90th
percentile level is calculated based on "all samples taken during a monitoring period" and does
not require that the minimum required number of samples must be collected in order to calculate
the 90th percentile level. [40 CFR 141.80(c)]
1 See March 9, 2004 memorandum from Cynthia Dougherty to Jane Downing at
http://www.epa. gov/safewater/lcrmr/pdfs/memo_lcmr_lead_compliance_calculation.pdf
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A system which fails to collect the
minimum required number of samples incurs
a monitoring and reporting violation and is
thus required to conduct Tier 3 Public
Notification (PN) [40 CFR 141.204(a)] and
report the violation in its Consumer
Confidence Report (CCR) [40 CFR
141.15 3 (f)( 1)]. The system will return to
compliance for the monitoring and reporting
violation when it completes these tasks and
has completed appropriate monitoring and
reporting for two consecutive 6-month
monitoring periods (or one round of
monitoring for a system on reduced
monitoring). [State Implementation Guidance
for the LCRMR, EPA-816-R-01 -021 ]
5) What is a proper sample?
We have received numerous requests
to clarify the LCR with respect to proper
samples and grounds for invalidation.
The LCR was designed to ensure that samples are collected from locations which have
the highest risk of elevated lead concentrations. The rule established a tiering system
(Attachment A) that would guide utilities in selecting locations for tap sampling that are
considered high risk and requires that the sampling pool be comprised of Tier 1 sites, if they are
available. [40 CFR 141.86(a)]
The LCR also defines a proper sample as a first draw sample, 1 liter in volume, that is
taken after water has been standing in plumbing for at least six hours, and from an interior tap
typically used for consumption - cold water kitchen or bathroom sink tap in residences. [40 CFR
141.86(b)(2)] There is no outer limit on standing time.
To ensure that sampling is conducted properly, the LCR requires that samples be
collected by the system or by residents if they have been properly instructed by the water system.
As added insurance that the system gives proper instructions, the rule does not allow water
systems to challenge sample results based on alleged homeowner errors in sample collection. [40
CFR141.86(b)(2)]
Calculating the 90th Percentile
40 CFR §141.80(c)(3) - "The 90th percentile lead and
copper levels shall be computed as follows:
(i) The results of all lead and copper samples taken
during a monitoring period shall be placed in
ascending order from the sample with the lowest
concentration to the sample with the highest
concentration. Each sampling result shall be assigned
a number, ascending by single integers beginning with
the number 1 for the sample with the lowest
contaminant level. The number assigned to the sample
with the highest contaminant level shall be equal to the
total number of samples taken.
(ii) The number of samples taken during the
monitoring period shall be multiplied by 0.9.
(iii) The contaminant concentration in the numbered
sample yielded by the calculation in paragraph
(c)(3)(ii) is the 90th percentile contaminant level.
(iv) For water systems serving less than 100 people
that collect 5 samples per monitoring period, the 90th
percentile is computed by taking the average of the
highest and second highest concentrations.
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6) How can utilities avoid problems with sample collection?
In order to avoid any problems with sample collection, the utility may wish to do the
sampling itself or review the sample collection information before sending it to the lab. If the
utility chooses to use residents to perform the sampling, it should provide clear instructions and a
thorough chain-of-custody form for residents to fill out when the sample is taken. This will
allow the laboratory or utility to eliminate improperly collected samples prior to the actual
analysis. For example, if a sample bottle is only half full, then it should not be analyzed by the
laboratory. Likewise, if the documentation accompanying the sample indicates that it was taken
from an outside tap, the sample should not be analyzed. Systems may need to make
arrangements to collect replacement samples for samples that are not analyzed by the laboratory.
Once a sample is analyzed, the results may not be challenged by the water system. As
explained by Question #1 of this memorandum, the results for all samples from the compliance
sampling pool must be included in the 90th percentile calculation unless there are grounds for
invalidation. Improper sampling by residents is not a grounds for invalidation under 40 CFR
141.86(f).
7) On what grounds may a sample be invalidated?
The regulations allow the state to invalidate a lead or copper tap sample only if it can
document that at least one of the following conditions has occurred:
1 . The laboratory establishes that improper sample analysis caused erroneous results;
2. The state determines that the sample was taken from a site that did not meet the site
selection criteria of this section;
3. The sample container was damaged in transit; or
4. There is substantial reason to believe that the sample was subject to tampering. [40 CFR
We interpret the second condition to mean a site that is not part of the compliance
sampling pool, that has not been identified as a Tier 1 or other high risk site, or that has been
altered in such a way that it no longer meets the criteria of a high-risk site (e.g., new plumbing or
the addition of a water softener).
It is important to note that states may not invalidate a sample solely on the grounds that a
follow-up sample result is higher or lower than that of the original sample. [40 CFR 141.86(f)(3)]
The system must report the results of all the samples to the state, and provide supporting
documentation for all samples it believes should be invalidated. [40 CFR 141.86(f)(2)] The state
must provide its formal decision on whether or not to invalidate the sample(s) in writing. If a
state makes a determination to invalidate the sample, the decision and the rationale for the
decision must be provided in writing. [40 CFR 141.86(f)(3)]
In conducting the national implementation review, we have noticed that some utilities
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may have requested invalidation of samples because they believe that there was improper
sampling on the part of the homeowner (e.g., drawing water from the incorrect tap). This is a
concern because there may be a tendency to only consider sampling errors when there are high
results, even though there could be sampling errors that would lead to artificially low results
(e.g., collecting a sample after the line was flushed). In any event, EPA takes a strict
interpretation of the invalidation requirements in the LCR. If a system allows residents to
perform sampling as part of the targeted sampling pool, the system may not challenge the
accuracy of sampling results because it believes there were errors in sample collection. [40 CFR
141.86(b)(2)] The state may only invalidate samples based on the criteria described above.
In sum, if a water system (1) sends a sample bottle to a home within its compliance
sampling pool, (2) receives the sample back from the homeowner, (3) sends the sample to the
laboratory for analysis, and (4) receives results from the analysis back from the lab; that result
must be used in calculating the 90th percentile. The only exception to this is if the state
invalidates the result in accordance with the regulation.
Conclusion
The Agency is continuing its wide-ranging review of implementation of the LCR and will
use the information to determine what changes should be made to existing guidance, training
and/or the regulatory requirements. This memo should help to provide clarification on issues
related to calculating the 90th percentile and proper management of tap samples as required under
the LCR. Please work with your states to ensure that they understand the requirements so that
they may work with the public water systems under their jurisdiction to address any
misinterpretations of the regulations. If you have additional questions or concerns, please contact
me or have your staff contact Cynthia Dougherty, Director of the Office of Ground Water and
Drinking Water at (202) 564-3750, or Ronald Bergman, Associate Chief of the Protection Branch
in the Office of Ground Water and Drinking Water, at (202) 564-3823.
Attachment
cc: Regional Drinking Water Branch Chiefs
James Taft, Association of State Drinking Water Administrators
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Attachment A
Tiering Classification System for Selection of Monitoring Sites
Tiering Classification
If you are a Community Water System
If you are an Non-transient
Noncommunity Water System
Tier 1 sampling sites are single family
structures: with copper pipes with lead solder
installed after 1982 (but before the effective
date of your State's lead ban) or contain lead
pipes; and/or that are served by a lead service
line.
Note: When multiple-family residences
(MFRs) comprise at least 20% of the structures
served by a water system, the system may
count them as Tier 1 sites.
Tier 2 sampling sites consist of buildings,
including MFRs: with copper pipes with lead
solder installed after 1982 (but before effective
date of your State's lead ban) or contain lead
pipes; and/or that are served by a lead service
line.
Tier 3 sampling sites are single family
structures w/ copper pipes having lead solder
installed before 1983.
Tier 1 sampling sites consist of buildings:
with copper pipes with lead solder installed
after 1982 (but before the effective date of
your State's lead ban)or contain lead pipes;
and/or
that are served by a lead service line.
Tier 2 sampling sites consist of buildings
with copper pipes with lead solder installed
before 1983.
Tier 3: Not applicable.
Note:
• All States were required to ban the use of lead solder in all public water systems, and all
homes and buildings connected to such systems by June 1988 (most States adopted the
ban in 1987 or 1988). Contact the Drinking Water Program in your State to find out the
effective date.
• A community water system with insufficient tier 1, tier 2 and tier 3 sampling sites, or an
non-transient noncommunity water system with insufficient tier 1 and tier 2 sites, shall
complete its sampling pool with representative sites throughout the distribution system.
For the purposes of this paragraph, a representative site is a site in which the plumbing
materials used at that site would be commonly found at other sites served by the water
system. [40 CFR 141.86(a)(5) and (7)]
Source: Lead and Copper Monitoring and Reporting Guidance for Public Water Systems, EPA-
816-R-02-009
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Appendix A. Summary of Pertinent Drinking Water Regulations
This page intentionally left blank.
Simultaneous Compliance Guidance Manual A-24 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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&EPA
1 The June 1989 Rule was
revised as follows: Corrections and
Technical Amendments, 6/19/90
and Partial Stay of Certain Provi-
sions (Variance Criteria) 56 FR
1556-1557, Vol 56, No 10.
Note: The TCR is currently
undergoing the 6 year review
process and may be subject to
change.
United States
Environmental Protection
Agency
Office of Water
(4606)
EPA 816-F-01-035
November 2001
www.epa.gov/safewater
Total Coliform Rule:
A Quick Reference Guide
Overview of the Rule
Title
Purpose
General
Description
Utilities
Covered
Total Coliform Rule (TCR)
54 FR 27544-27568, June 29, 1989, Vol. 54, No. 1241
Improve public health protection by reducing fecal pathogens to minimal levels
through control of total collform bacteria, Including fecal conforms and Escherichia
coli (E. coli).
Establishes a maximum contaminant level (MCL) based on the presence or absence
of total conforms, modifies monitoring requirements Including testing for fecal
conforms or E. coli, requires use of a sample siting plan, and also requires sanitary
surveys for systems collecting fewer than five samples per month.
The TCR applies to all public water systems.
Public Health Benefits
Implementation
of the TCR has
resulted In ...
* Reduction In risk of Illness from disease causing organisms associated with
sewage or animal wastes. Disease symptoms may Include diarrhea, cramps,
nausea, and possibly jaundice, and associated headaches and fatigue.
ROUTINE Sampling Requirements
Total collform samples must be collected at sites which are representative of water quality
throughout the distribution system according to a written sample siting plan subject to state
review and revision.
Samples must be collected at regular time Intervals throughout the month except groundwater
systems serving 4,900 persons or fewer may collect them on the same day.
Monthly sampling requirements are based on population served (see table on next page for the
minimum sampling frequency).
A reduced monitoring frequency may be available for systems serving 1,000 persons or fewer
and using only ground water If a sanitary survey within the past 5 years shows the system Is
free of sanitary defects (the frequency may be no less than 1 sample/quarter for community
and 1 sample/year for non-community systems).
Each total collform-posltlve routine sample must be tested for the presence of fecal conforms or
E. coli.
If any routine sample Is total collform-posltlve, repeat samples are required.
REPEAT Sampling Requirements
> Within 24 hours of learning of a total collform-posltlve ROUTINE sample result, at least 3 REPEAT
samples must be collected and analyzed for total conforms:
^ One REPEAT sample must be collected from the same tap as the original sample.
^ One REPEAT sample must be collected within five service connections upstream.
^ One REPEAT sample must be collected within five service connections downstream.
* Systems that collect 1 ROUTINE sample per month or fewer must collect a 4th REPEAT sample.
* If any REPEAT sample is total coliform-positive:
* The system must analyze that total coliform-positive culture for fecal conforms or E.coli.
* The system must collect another set of REPEAT samples, as before, unless the MCL has been
violated and the system has notified the state.
Additional ROUTINE Sample Requirements
A positive ROUTINE or REPEAT total coliform result requires a minimum of five ROUTINE
samples be collected the following month the system provides water to the public unless
waived by the state.
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For additional information on
theTCR
Call the Safe Drinking Water
Hotline at 1-800-426-4791; visit
the EPA web site at
www.epa.gov/safewater/mdbp/
mdbp.html; or contact your state
drinking water representative.
2 The revised Public Notification
Rule will extend the period allowed
for public notice of monthly violations
to 30 days and shorten the period for
acute violations to 24 hours. These
revisions are effective for all systems
by May 6, 2002 and are detailed in
40 CFR Subpart Q.
Public Water System ROUTINE Monitoring Frequencies
Population
25-1,000*
1,001-2,500
2,501-3,300
3,301-4,100
4,101-4,900
4,901-5,800
5,801-6,700
6,701-7,600
7,601-8,500
8,501-12,900
12,901-17,200
17,201-21,500
Minimum
Samples/ Month
1
10
15
20
Population
21,501-25,000
25,001-33,000
33,001-41,000
41,001-50,000
50,001-59,000
59,001-70,000
70,001-83,000
83,001-96,000
96,001-130,000
130,001-220,000
220,001-320,000
320,001-450,000
Minimum
Samples/ Month
25
30
40
50
60
70
80
90
100
120
Population
450,001-600,000
600,001-780,000
780,001-970,000
970,001-1,230,000
1,230,001-1,520,000
1,520,001-1,850,000
1,850,001-2,270,000
2,270,001-3,020,000
3,020,001-3,960,000
a 3,960,001
Minimum
Samples/ Month
210
240
270
300
330
360
390
420
450
480
150
180
includes PWSs which have at least 15 service connections, but serve <25 people.
What are the Other Provisions?
Systems collecting fewer than 5
ROUTINE samples per month .. .
Systems using surface water or ground
water under the direct Influence of
surface water (GWUDI) and meeting
filtration avoidance criteria ..
Must have a sanitary survey every 5 years (or every 10
years If It Is a non-community water system using
protected and disinfected ground water).**
Must collect and have analyzed one collform sample
each day the turbidity of the source water exceeds 1
NTU. This sample must be collected from a tap near the
first service connection.
** As per the IESWTR, states must conduct sanitary surveys for community surface water and GWUDI systems in this
category every 3 years (unless reduced by the state based on outstanding performance).
How is Compliance Determined?
Compliance Is based on the presence or absence of total conforms.
Compliance Is determined each calendar month the system serves water to the public (or each
calendar month that sampling occurs for systems on reduced monitoring).
The results of ROUTINE and REPEAT samples are used to calculate compliance.
A Monthly MCL Violation is Triqqered if
A system collecting fewer than 40
samples per month ...
A system collecting at least 40
samples per month ...
Has greater than 1 ROUTINE/REPEAT sample per month which
is total coliform-positive.
Has greater than 5.0 percent of the ROUTINE/REPEAT samples
in a month total coliform-positive.
Any public water system . ..
Has any fecal coliform- or £. co/i-positive REPEAT sample or
has a fecal coliform- or £. co//-positive ROUTINE sample
| followed by a total coliform-positive REPEAT sample.
What are the Public Notification and Reporting Requirements?
For a Monthly MCL Violation
For an Acute MCL Violation
Systems with ROUTINE or
REPEAT samples that are fecal
coliform- or £. co//-positive . . .
* The violation must be reported to the state no later than the
end of the next business day after the system learns of the
violation.
* The public must be notified within 14 days.2
* The violation must be reported to the state no later than the
end of the next business day after the system learns of the
violation.
* The public must be notified within 72 hours.2
Must notify the state by the end of the day they are notified of the
result or by the end of the next business day if the state office is
already closed.
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oEPA
United States
Environmental Protection
Agency
Office of Water
(4606)
EPA816-F-01-010
May 2001
www.epa.gov/safewater
Stage 1 Disinfectants and Disinfection
Byproducts Rule:
A Quick Reference Guide
Overview of the Rule
Title
Purpose
General
Description
Utilities
Covered
Stage 1 Disinfectants and Disinfection Byproducts Rule (Stage 1 DBPR)
63 FR 69390 - 69476, December 16, 1998, Vol. 63, No. 241
Revisions to the Interim Enhanced Surface Water Treatment Rule (IESWTR), the Stage 1
Disinfectants and Disinfection Byproducts Rule (Stage 1 DBPR), and Revisions to State Primacy
Requirements to Implement the Safe Drinking Water Act (SDWA) Amendments
66 FR 3770, January 16, 2001, Vol 66, No. 29
Improve public health protection by reducing exposure to disinfection byproducts. Some
disinfectants and disinfection byproducts (DBPs) have been shown to cause cancer and
reproductive effects in lab animals and suggested bladder cancer and reproductive effects in
humans.
The Stage 1 DBPR is the first of a staged set of rules that will reduce the allowable levels of
DBPs in drinking water. The new rule establishes seven new standards and a treatment
technique of enhanced coagulation or enhanced softening to further reduce DBP exposure. The
rule is designed to limit capital investments and avoid major shifts in disinfection technologies
until additional information is available on the occurrence and health effects of DBPs.
The Stage 1 DBPR applies to all sizes of community water systems and nontransient
noncommunity water systems that add a disinfectant to the drinking water during any part of the
treatment process and transient noncommunity water systems that use chlorine dioxide.
Public Health Benefits
Implementation of the
Stage 1 DBPR will
result in ...
Estimated impacts of
the Stage 1 DBPR
include . . .
As many as 140 million people receiving increased protection from DBPs.
24 percent average reduction nationally in trihalomethane levels.
Reduction in exposure to the major DBPs from use of ozone (DBP = bromate) and
chlorine dioxide (DBP = chlorite).
National capital costs: $2.3 billion
National total annualized costs to utilities: $684 million
95 percent of households will incur an increase of less than $1 per month.
4 percent of households will incur an increase of $1-10 per month.
<1 percent of households will incur an increase of $10-33 per month.
Critical Deadlines and Requirements
January 1, 2002
January 1, 2004
Surface water systems and ground water systems under the direct
influence of surface water serving £10.000 people must comply with the
Stage 1 DBPR requirements.
Surface water systems and ground water systems under the direct
influence of surface water serving < 10,000, and all ground water systems
must comply with the Stage 1 DBPR requirements.
For States
December 16, 2000
December 16, 2002
States submit Stage 1 DBPR primacy revision applications to EPA
(triggers interim primacy).
Primacy extension deadline - all states with an extension must submit
primacy revision applications to EPA.
-------
For additional information
on the Stage 1 DBPR
Call the Safe Drinking Water
Hotline at 1-800-426-4791;
visit the EPA web site at
www.epa.gov/safewater; or
contact your State drinking
water representative.
Additional material is
available at www.epa.gov/
safewater/md bp/
implement.html.
Regulated Contaminants/Disinfectants
Regulated
Contaminants
Total Trihalomethanes (TTHM)
Chloroform
Bromodichloromethane
Dibromochloromethane
Bromoform
Five Haloacetic Acids (HAAS)
Monochloroacetic acid
Dichloroacetic acid
Trichloroacetic acid
Bromoacetic acid
Dibromoacetic acid
Bromate (plants that use ozone)
Chlorite (plants that use chlorine
dioxide)
MCL
(mg/L)
0.080
0.060
0.010
1.0
MCLG
(mg/L)
zero
0.06
zero
zero
0.3
zero
0.8
Regulated
Disinfectants
Chlorine
Chloramines
Chlorine dioxide
MRDL*
(mg/L)
4.0 as CI2
4.0 as CI2
0.8
MRDLG*
(mg/L)
4
4
0.8
*Stage 1 DBPR includes maximum residual
disinfectant levels (MRDLs) and maximum
residual disinfectant level goals (MRDLGs)
which are similar to MCLs and MCLGs, but for
disinfectants.
Treatment Technique
Enhanced coagulation/enhanced softening to improve removal of DBF precursors (See Step 1 TOC Table) for
systems using conventional filtration treatment.
Step 1 TOC Table - Required % Removal of TOC
Source Water
TOC (mg/L)
> 2.0 to 4.0
> 4.0 to 8.0
>8.0
Source Water Alkalinity, mg/L as CaCO3
0-60
35.0%
45.0%
50.0%
> 60-120
25.0%
35.0%
40.0%
> 120
15.0%
25.0%
30.0%
1 Systems meeting at least one of the alternative compliance criteria in the rule are not required to meet the
removals in this table.
2Systems practicing softening must meet the TOC removal requirements in the last column to the right
Routine Monitoring Requirements
TTHM/HAA5
Bromate
Chlorite
Chlorine dioxide
Chlorine/Chloramines
DBF precursors
Coverage
Surface and ground water
under the direct influence of
surface water serving S 10,000
Surface and ground water
under the direct influence of
surface water serving 500 -
9,999
Surface and ground water
under the direct influence of
surface water serving < 500
Ground water serving S 10,000
Ground water serving < 10,000
Ozone plants
Chlorine dioxide plants
Chlorine dioxide plants
All systems
Conventional filtration
Monitoring
Frequency
4/plant/quarter
1 /plant/quarter
1/plant/year in month of
warmest water temperature**
1 /plant/quarter
1/plant/year in month of
warmest water temperature**
Monthly
Daily at entrance to
distribution system; monthly
in distribution system
Daily at entrance to
distribution system
Same location and frequency
as TCR sampling
Monthly for total organic
carbon and alkalinity
Compliance
Running annual average
Running annual average
Running annual average
of increased monitoring
Running annual average
Running annual average
of increased monitoring
Running annual average
Daily/follow-up monitoring
Daily/follow-up monitoring
Running annual average
Running annual average
** System must increase monitoring to 1 sample per plant per quarter if an MCL is exceeded.
-------
SEPA
United States
Environmental Protection
Agency
Office of Water
(4606)
EPA816-F-01-011
May 2001
www.epa.gov/safewater
Interim Enhanced Surface Water
Treatment Rule:
A Quick Reference Guide
Overview of the Rule
Title
Purpose
General
Description
Utilities
Covered
Interim Enhanced Surface Water Treatment Rule (IESWTR)
63 FR 69478 - 69521, December 16, 1998, Vol. 63, No. 241
Revisions to the Interim Enhanced Surface Water Treatment Rule (IESWTR), the Stage 1
Disinfectants and Disinfection Byproducts Rule (Stage 1 DBPR), and Revisions to State
Primacy Requirements to Implement the Safe Drinking Water Act (SDWA) Amendments
66 FR 3770, January 16, 2001, Vol 66, No. 29
Improve public health control of microbial contaminants, particularly Cryptosporidium.
Prevent significant increases in microbial risk that might otherwise occur when systems
implement the Stage 1 Disinfectants and Disinfection Byproducts Rule.
Builds upon treatment technique approach and requirements of the 1989 Surface Water
Treatment Rule. Relies on existing technologies currently in use at water treatment plants.
Sanitary survey requirements apply to all public water systems using surface water or
ground water under the direct influence of surface water, regardless of size. All remaining
requirements apply to public water systems that use surface water or ground water under
the direct influence of surface water and serve 10,000 or more people.
Major Provisions
Regulated Contaminants
Cryptosporidium
Turbidity Performance
Standards
^ Maximum contaminant level goal (MCLG) of zero.
^ 99 percent (2-log) physical removal for systems that filter.
* Include in watershed control program for unfiltered systems.
Conventional and direct filtration combined filter effluent:
^ < 0.3 nephelometric turbidity units (NTU) in at least 95 percent of
measurements taken each month.
^ Maximum level of 1 NTU.
Turbidity Monitoring Requirements
(Conventional and Direct Filtration)
Combined Filter Effluent
Individual Filter Effluent
^ Performed every 4 hours to ensure compliance with turbidity
performance standards.
* Performed continuously (every 15 minutes) to assist treatment plant
operators in understanding and assessing filter performance.
Additional Requirements
* Disinfection profiling and benchmarking.
* Construction of new uncovered finished water storage facilities prohibited.
* Sanitary surveys, conducted by the state, for all surface water and ground water under the
direct influence of surface water systems regardless of size (every 3 years for community water systems
and every 5 years for noncommunity water systems).
-------
Profiling and Benchmarking
For additional information
on the IESWTR
Call the Safe Drinking Water
Hotline at 1-800-426-4791;
visit the EPA web site at
www.epa.gov/safewater; or
contact your State drinking
water representative.
Additional material is
available at www.epa.gov/
safewater/md bp/
implement.html.
Public water systems must evaluate impacts on microbial risk before changing
disinfection practices to ensure adequate protection is maintained. The three major steps
are:
> Determine if a public water system needs to profile based on TTHM and HAAS levels
(applicability monitoring)
^ Develop a disinfection profile that reflects daily Giardia lamblia inactivation for at least a year
(systems using ozone or chloramines must also calculate inactivation of viruses)
* Calculate a disinfection benchmark (lowest monthly inactivation) based on the profile and
consult with the state prior to making a significant change to disinfection practices
Critical Deadlines and Requirements
For Drinking Water Systems
February 16, 1999
March 1999
April 16, 1999
December 31, 1999
April 1, 2000
March 31, 2001
January 1, 2002
Construction of uncovered finished water reservoirs is prohibited.
Public water systems lacking ICR or other occurrence data begin 4 quarters of
applicability monitoring for TTHM and HAAS to determine if disinfection
profiling is necessary.
Systems that have 4 consecutive quarters of HAAS occurrence data that meet
the TTHM monitoring requirements must submit data to the state to determine
if disinfection profiling is necessary.
Public water systems with ICR data must submit it to states to determine if
disinfection profiling is necessary.
Public water systems must begin developing a disinfection profile if their annual
average (based on 4 quarters of data) for TTHM is greater than or equal to
0.064 mg/L or HAAS is greater than or equal to 0.048 mg/L.
Disinfection profile must be complete.
Surface water systems or ground water under the direct influence of surface
water systems serving 10,000 or more people must comply with all IESWTR
provisions (e.g., turbidity standards, individual filter monitoring).
For States
December 16, 2000
January 2002
December 16, 2002
December 2004
December 2006
States submit IESWTR primacy revision applications to EPA (triggers interim
primacy).
States begin first round of sanitary surveys.
Primacy extension deadline - all states with an extension must submit primacy
revision applications to EPA.
States must complete first round of sanitary surveys for community water
systems.
States must complete first round of sanitary surveys for noncommunity water
systems.
Public Health Benefits
Implementation of
the IESWTR will
result in ...
Estimated impacts of
the IESWTR
include ...
Increased protection against gastrointestinal illnesses from
Cryptosporidium and other pathogens through improvements in filtration.
Reduced likelihood of endemic illness from Cryptosporidium by 110,000 to
463,000 cases annually.
Reduced likelihood of outbreaks of cryptosporidiosis.
National total annualized cost: $307 million
92 percent of households will incur an increase of less than $1 per month.
Less than 1 percent of households will incur an increase of more than $5 per
month (about $8 per month).
-------
s»EPA
United States
Environmental Protection
Agency
t For additional information on
J theLTlESWTR
< Call the Safe Drinking Water
Hotline at 1-800-426-4791; visit
the EPA web site at
www.epa.gov/safewater/mdbp/
It1eswtr.html; or contact your
State drinking water
representative.
1 This frequency may be reduced
by the State to once per day for
systems using slow sand/alternative
filtration or for systems serving 500
persons or fewer regardless of the
type of filtration used.
Long Term 1 Enhanced Surface
Water Treatment Rule:
A Quick Reference Guide
Title
Purpose
General
Description
Utilities
Covered
Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR)
67 FR 1812, January 14, 2002, Vol. 67, No. 9
Improve public health protection through the control of microbial contaminants,
particularly Cryptosporidium. Prevent significant increases in microbial risk that
might otherwise occur when systems implement the Stage 1 Disinfectants and
Disinfection Byproducts Rule.
Builds upon the requirements of the 1989 Surface Water Treatment Rule (SWTR).
Smaller system counterpart of the Interim Enhanced Surface Water Treatment Rule
(IESWTR).
Public water systems that use surface water or ground water under the direct
influence of surface water (GWUDI) and serve fewer than 10,000 people.
'
Major Provisions
Control of
Cryptosporidium
Combined Filter
Effluent (CFE)
Turbidity
Performance
Standards
Filter
1
IFE
Filter Filter
2 3
IFE
l
IFE
CFE
r
* The maximum contaminant level goal (MCLG) is set at zero.
* Filtered systems must physically remove 99% (2-log) of Cryptosporidium.
* Unfiltered systems must update their watershed control programs to
minimize the potential for contamination by Cryptosporidium oocysts.
> Cryptosporidium is included as an indicator of GWUDI.
Specific CFE turbidity requirements depend on the type of filtration
used by the system.
Conventional and direct filtration:
* £ 0.3 nephelometric turbidity units (NTU) in at least 95% of measurements
taken each month.
* Maximum level of turbidity: 1 NTU.
Slow sand and diatomaceous earth (DE) filtration:
* Continue to meet CFE turbidity limits specified in the SWTR:
• 1 NTU in at least 95% of measurements taken each month.
• Maximum level of turbidity: 5 NTU.
Alternative technologies (other than conventional, direct, slow sand, or DE):
* Turbidity levels are established by the State based on filter
demonstration data submitted by the system.
• State-set limits must not exceed 1 NTU (in at least 95% of
measurements) or 5 NTU (maximum).
Combined Filter
Effluent
Individual Filter
Effluent (IFE)
(for systems using
conventional and
direct filtration only)
Performed at least every 4 hours to ensure compliance with CFE
turbidity performance standards.1
Since the CFE may meet regulatory requirements even though one
filter is producing high turbidity water, the IFE is measured to assist
conventional and direct filtration treatment plant operators in
understanding and assessing individual filter performance.
* Performed continuously (recorded at least every 15 minutes).
> Systems with two or fewer filters may conduct continuous monitoring
of CFE turbidity in place of individual filter effluent turbidity monitoring.
> Certain follow-up actions are required if the IFE turbidity (or CFE for
systems with two filters) exceeds 1.0 NTU in 2 consecutive readings or
more (i.e., additional reporting, filter self-assessments, and/or
comprehensive performance evaluations (CPEs)).
-------
Disinfection Profiling and Benchmarking Requirements
Community and non-transient non-community public water systems must evaluate impacts on microbial risk before changing disinfection
practices to ensure adequate microbial protection is maintained. This is accomplished through a process called disinfection profiling and
benchmarking.
What are the disinfection profiling and benchmarking requirements?
> Systems must develop a disinfection profile, which is a graphical compilation of weekly inactivation of Giardia lamblia, taken on the
same calendar day each week over 12 consecutive months. (Systems using chloramines, ozone, or chlorine dioxide for primary
disinfection must also calculate inactivation of viruses). Results must be available for review by the State during sanitary surveys.
* A State may deem a profile unnecessary if the system has sample data collected after January 1, 1998-during the month of warmest
water temperature and at maximum residence time in the distribution system-indicating TTHM levels are below 0.064 mg/L and HAAS
levels are below 0.048 mg/L.
* Prior to making a significant change to disinfection practices, systems required to develop a profile must calculate a disinfection
benchmark and consult with the State. The benchmark is the calculation of the lowest monthly average of inactivation based on the
disinfection profile.
Additional Requirements
Construction of new uncovered finished water reservoirs is prohibited.
Critical Deadlines and Requirements
For Drinking Water Systems
March 15, 2002
July 1,2003
January 1, 2004
June 30, 2004
December 31, 2004
January 14, 2005
For States
January 2002
October 14, 2003
January 14, 2004
December 2004
January 14, 2006
December 2006
Construction of uncovered finished reservoirs is prohibited.
No later than this date, systems serving between 500-9,999 persons must report to the State:
> Results of optional monitoring which show levels of TTHM < 0.064 mg/L and HAAS < 0.048 mg/L, OR
^ System has started profiling.
No later than this date, systems serving fewer than 500 persons must report to the State:
> Results of optional monitoring which show levels of TTHM < 0.064 mg/L and HAAS < 0.048 mg/L, OR
^ System has started profiling.
Systems serving between 500 and 9,999 persons must complete their disinfection profile unless the State has
determined it is unnecessary.
Systems serving fewer than 500 persons must complete their disinfection profile unless the State has determined it is
unnecessary.
Surface water systems or GWUDI systems serving fewer than 10,000 people must comply with the applicable
LT1ESWTR provisions (e.g., turbidity standards, individual filter monitoring, Cryptosporidium removal requirements,
updated watershed control requirements for unfiltered systems).
As per the IESWTR, States begin first round of sanitary surveys (at least every 3 years for community water systems
and every 5 years for non-community water systems).
States are encouraged to submit final primacy applications to EPA.
Final primacy applications must be submitted to EPA unless granted an extension.
States must complete first round of sanitary surveys for community water systems (as per the IESWTR).
Final primacy revision applications from States with approved 2-year extension agreements must be submitted to EPA.
States must complete first round of sanitary surveys for non-community water systems (as per the IESWTR).
Public Health Benefits
Implementation of
the LT1ESWTR will
result in ...
Increased protection against gastrointestinal illnesses from Cryptosporidium and other pathogens through
improvements in filtration.
Reduced likelihood of endemic illness from Cryptosporidium by an estimated 12,000 to 41,000 cases annually.
Reduced likelihood of outbreaks of cryptosporidiosis.
Estimated impacts
of theLTIESWTR
include . . .
National total annualized cost: $39.5 million.
90% of affected households will incur an increase of less than $1.25 per month.
One percent of affected households are likely to incur an increase of more than $10 per month.
Office of Water (4606)
EPA 816-F-02-001
www.epa.gov/safewater
January 2002
-------
&EPA
United States
Environmental Protection
Agency
Office of Water
(4606)
EPA 816-F-01-019
June 2001
www.epa.gov/safewater
Filter Backwash Recycling Rule:
A Quick Reference Guide
Overview of the Rule
Title
Purpose
General
Description
Utilities
Covered
Filter Backwash Recycling Rule (FBRR)
66 FR 31086, June 8, 2001, Vol. 66, No. 111
Improve public health protection by assessing and changing, where
needed, recycle practices for improved contaminant control, particularly
microbial contaminants.
The FBRR requires systems that recycle to return specific recycle flows
through all processes of the system's existing conventional or direct
filtration system or at an alternate location approved by the state.
Applies to public water systems that use surface water or ground water
under the direct influence of surface water, practice conventional or
direct filtration, and recycle spent filter backwash, thickener supernatant,
or liquids from dewatering processes.
Public Health Benefits
Implementation of
FBRR will result in
Reduction in risk of illness from microbial pathogens in
drinking water, particularly Cryptosporidium.
Estimated impacts of
the FBRR include . . .
FBRR will apply to an estimated 4,650 systems serving
35 million Americans.
Fewer than 400 systems are expected to require capital
improvements.
Annualized capital costs incurred by public water systems
associated with recycle modifications are estimated to be
$5.8 million.
Mean annual cost per household is estimated to be less
than $1.70 for 99 percent of the affected households and
between $1.70 and $100 for the remaining one percent of
affected households.
Conventional and Direct Filtration
Conventional filtration, as defined in 40 CFR 141.2, is a series of processes including
coagulation, flocculation, sedimentation, and filtration resulting in substantial
particulate removal. Conventional filtration is the most common type of filtration.
Direct filtration, as defined in 40 CFR 141.2, is a series of processes including
coagulation and filtration, but excluding sedimentation, and resulting in substantial
particulate removal. Typically, direct filtration can be used only with high-quality raw
water that has low levels of turbidity and suspended solids.
-------
ass
Spent Filter Backwash Water - A stream containing particles that are dislodged from
filter media when water is forced back through a filter (backwashed) to clean the filter.
Thickener Supernatant - A stream containing the decant from a sedimentation basin,
clarifier or other unit that is used to treat water, solids, or semi-solids from the primary
treatment processes.
Liquids From Dewatering Processes - A stream containing liquids generated from a
unit used to concentrate solids for disposal.
Critical Deadlines and Requirements
For Drinking Water Systems
December 8, 2003
June 8, 2004
June 8, 2006
Submit recycle notification to the state.
Return recycle flows through the processes of a system's
existing conventional or direct filtration system or an alternate
recycle location approved by the state (a 2-year extension is
available for systems making capital improvements to modify
recycle location).
Collect recycle flow information and retain on file.
Complete all capital improvements associated with relocating
recycle return location (if necessary).
For States
June 8, 2003
June 8, 2005
States submit FBRR primacy revision application to EPA
(triggers interim primacy).
Primacy extension deadline - all states with an extension must
submit primacy revision applications to EPA.
"••"•"•"•'
Plant schematic showing origin of recycle flows, how recycle flows are conveyed,
and return location of recycle flows.
Typical recycle flows (gpm), highest observed plant flow experienced in the previous
year (gpm), and design flow for the treatment plant (gpm).
State-approved plant operating capacity (if applicable).
For additional information on
the FBRR
Call the Safe Drinking Water
Hotline at 1-800-426-4791; visit
the EPA web site at
www.epa.gov/safewater; or
contact your state drinking water
representative.
Additional material is available at
www.epa.gov/safewater/
f ilterbackwash .html.
What recycle flow information d
to collect and retain on file?
Copy of recycle notification and information submitted to the state.
List of all recycle flows and frequency with which they are returned.
Average and maximum backwash flow rates through filters, and average and
maximum duration of filter backwash process (in minutes).
Typical filter run length and written summary of how filter run length is determined.
Type of treatment provided for recycle flows.
Data on the physical dimension of the equalization and/or treatment units, typical
and maximum hydraulic loading rates, types of treatment chemicals used,
average dose, frequency of use, and frequency at which solids are removed, if
applicable.
-------
Appendix B
Case Studies
-------
This page intentionally left blank.
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Appendix B. Case Studies
This page intentionally left blank.
Simultaneous Compliance Guidance Manual B-4 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
Case Study #1
Improving and Optimizing Current Operations
Owenton Water Works and Kentucky American TriVillage
Owenton, Kentucky
This case study provides an example of how two small PWSs, both using water treated by
the same conventional filtration plant, worked together to change chlorination practices to their
existing treatment and operations to reduce TTHM. Reducing TTHM was the primary objective,
due to the timing of this work beginning in late 1999 prior to regulatory limits for these systems
serving a combined population under 10,000.
Changes described here took place primarily over the first 6 months of 2000 and were
made in a series of carefully planned and monitored steps in close consultation with the state
regulatory officials and with knowledge of available EPA regulations and guidance. This work
has also been successful in reducing HAA5s as these systems completed the first year (2004) in
compliance with the 80/60 THM/HAA limits.
Prior to moving the point of chlorination, the following steps were carried out:
1) Enhanced coagulation was initiated at lower pH to improve TOC removal and sodium
hydroxide (caustic soda) was added to maintain distribution corrosion control;
2) Potassium permanganate feed to the raw water was optimized to control source water
manganese and to provide reliable pre-oxidation in anticipation of moving the
chlorine application point; and
3) In-plant chlorine disinfection contact time was assessed and operations revised to
increase chlorine retention time in the plant clearwell. This step included trending 12
months of disinfection data in the plant and consultation with the state. The state
provided a list of additional source monitoring (microbiological and other related
water quality parameters from source through distribution) to be conducted prior to
and following the change in chlorine application point.
The point of chlorination was then moved by turning off the chlorine feed to the rapid
mix portion of plant treatment and increasing chlorine at the application points just before and
after the filters to provide the required residuals in the plant clearwell and through distribution.
This case study is documented in Routt (2004) and Routt and Pizzi (2000). Readers may
refer to those references for more details. Updates were also provided for this case study by J.
Routt in January 2005.
Introduction
The Owenton City Water Works operates a conventional 1 million gallons per day
treatment plant that uses water from an algae-rich reservoir. Approximately half of the water
that is produced by the Owenton facility is sold to Kentucky American Water Northern Division
(TriVillage), a privately owned water system. Owenton delivers the remainder of the water in its
Simultaneous Compliance Guidance Manual B-5 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
own distribution network. Together, the two systems serve fewer than 10,000 people. However,
for several years prior to this work (which began in late 1999), both systems had been regularly
issuing state-required health-based public notices due to elevated TTHM.
To define the factors contributing to the elevated DBFs, Kentucky American Water, in
cooperation with the City of Owenton, collected water quality data from both systems. These
data showed that the most effective solution to the elevated DBFs would be to switch to a source
water of higher quality. Switching source waters, however, was understood to be a long-term,
expensive project that would require designing and building new intake and transmission
facilities. In the meantime, the systems decided to make operational changes to improve water
quality before the completion of the new intake and transmission lines.
The Original Treatment Process at the Owenton WTP
The system used a high TOC, high alkalinity source water prone to fluctuating
manganese levels. Before treatment changes were made, chlorine was being added at the rapid
mix and again at booster stations to provide required free chlorine residuals through the
distribution system. The treatment plant was using alum-lime coagulation with a pH of
approximately 7.8, and was achieving less than 28 percent TOC removal. This TOC removal
efficiency would not meet the Step 1 requirements of the Stage 1 D/ DBPR for the system. In
addition, monitoring showed that TTHM levels were elevated leaving the treatment plant and
increased substantially with retention time and re- chlorination through the distribution network.
Simultaneous Compliance Issues Faced by the Utilities
The combined systems had high TTHM concentrations and were faced with the challenge
of complying with upcoming Stage 1 D/DBPR and Stage 2 DBPR requirements. Priorities and
plans had to be clearly set to help ensure ongoing compliance with other regulations that stood to
be impacted by treatment changes to reduce DBPs-such as SWTR disinfection and filtered
turbidity requirements, LCR corrosion control requirements and TCR microbiological control
requirements. To that end, the systems embarked upon a cooperative effort to proceed through
steps to improve DBFs for the short term-using existing source water and treatment and
distribution facilities-while keeping the multiple regulatory requirements in mind.
Steps Taken by the Utilities
Profiles of TOC removal, TTHM formation, and disinfection were collected through the
plant and distribution system. These process profiles showed that TOC was not being effectively
removed, and that high levels of TTHM and HAAS were being formed in the treatment plant.
Treatment changes, therefore, consisted of maximizing TOC removal and optimizing
chlorine disinfectant application. Operational changes were made in a phased process over
several months, with state approval granted for each step. The results of each step were
evaluated before the systems proceeded to the next phase.
Simultaneous Compliance Guidance Manual B-6 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
Enhancing Coagulation
The removal of TOC was increased by making several relatively simple changes to the
coagulation process in the Owenton treatment plant. Coagulation and TOC removal were
enhanced by ceasing pre-lime application, and approximately doubling the alum dose to lower
the treated water pH to 6.9. The change in coagulation chemicals required addition of a
postfiltration caustic feed (sodium hydroxide) to adjust the finished water's pH to 7.6-7.8 for
distribution system corrosion control.
In addition, a switch from alum to ferric chloride was made in order to improve the solids
handling in the plant's solids-contact upfiow clarifier. Ferric chloride was expected to produce
good TOC removal with less chemical, and to produce a more stable floe, less prone to upset and
carry-over onto filters. These expectations were met.
Changes to the coagulation process roughly doubled the TOC removal and decreased
chlorine demand. Chlorine residuals persisted noticeably longer in the distribution system,
which allowed the systems to reduce their re- chlorination doses at the master metering points in
the distribution system. Levels of TTHM, however, were decreased by only 15 percent. The
next step was to evaluate plant disinfection and seek state approval to move the point of
chlorination to later in the treatment process.
Converting to Top-of-Filter Chlorination
Prior to moving the chlorination point, the Owenton plant was thoroughly assessed for
adequate disinfection contact time. Tracer studies were conducted of the clearwell, which is
well-baffled, and operational guidelines were changed to increase the minimum water level in
the clearwell which effectively increased the chlorine disinfection contact time with filtered
water. This was to offset contact time that would be lost when chlorine application was moved
from rapid mix to the top of the filters. Potassium permanganate pretreatment procedures were
revised to incorporate regular demand tests to improve dosing accuracy and to reduce chlorine
oxidant demand. It was emphasized that, once the point of chlorination was moved to the top of
the filter, permanganate would be the only pre-oxidant. Therefore, optimization would be
critical to good coagulation of natural organics and to prevent manganese carryover when
treating the fluctuating dissolved manganese in the source water.
The state approved the system's proposal to switch to ferric chloride coagulant, followed
by post-caustic for corrosion control, and moving the point of chlorination to the top of the
filters. The changes were made in sequence and with close supervision and monitoring. The
change in point of chlorination was approved with the contingency that additional testing would
be conducted before and after the change, in order to verify adequate disinfection and good
overall water quality. This additional testing included TOC and organic nitrogen source water
monitoring, as well as heterotrophic and total coliform bacteria monitoring through the treatment
plant and distribution network.
Optimization of Booster Chlorination
In addition to the changes made at the Owenton treatment plant, both water systems have
worked to optimize their distribution systems, and the purchaser, TriVillage, has optimized
Simultaneous Compliance Guidance Manual B-7 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
chlorine doses at the booster stations. The reduction in finished water TOC leaving the Owenton
plant has allowed for a reduction in the amount of booster chlorine needed to maintain a residual
throughout the distribution system. Both systems have conducted additional flushing and have
cleaned and inspected their storage tanks. Since the changes, lead and copper action levels and
TCR standards have been met in both distribution systems. The systems continued to conduct
extra testing for TOC, DBFs, chlorine residual, and HPCs to track distribution system water
quality. In 2004, the TOC and DBF "compliance" testing has replaced the earlier special testing.
Implementation and Operational Issues Faced by the Utilities
Overall, operational changes have gone smoothly. The greatest ongoing operational
impacts have been related to enhanced coagulation: an increase in (approximate doubling of)
chemical treatment costs, along with a need for increased attention to solids removal from the
up flow clarifier and filter backwash settling basins.
Post-filter caustic feed has necessitated cleaning of deposits from filtered water transfer
pumps just downstream of the application point. This caustic buildup did not become
problematic until 2004 - 4 years after the initiation of caustic feed. However, utilities are advised
to watch for caustic clogging in mechanical devises located immediately downstream of caustic
application points.
In the summer of 2001, source water dissolved manganese temporarily increased to levels
that could not be treated by potassium permanganate alone. The resulting discolored water
forced the system to return to minimal prechlorination and, then, to switch briefly to
polyaluminum chloride as coagulant. The polyaluminum chloride coagulated well at a higher pH
(8.0), which improved potassium permanganate removal of the dissolved manganese and
eliminated the need for pre-chlorine. Within a few weeks, the source water manganese levels
dropped, and the system returned to ferric chloride coagulation at lower pH. This scenario has
not recurred since.
Systems should be extremely careful when switching coagulants to ensure that they
maintain consistent particle and pathogen removal. The dosage of new coagulant needed should
be carefully calculated and confirmed with up-to-date jar testing using the water to be treated.
Results of the Steps Taken
Since changes were made in May 2000, filtered and distributed water quality compliance
has been maintained. TTHM levels have dropped below the 0.080 mg/L standard. Testing has
shown that HAAS levels have been reduced by more than half as well. As of 2004, the first year
of compliance TOC testing showed monthly removal ratios ranging from 1.96-2.35 and
averaging 2.19 for the year, and the RAAs for THM and HAAS levels were 74 and 47 ug/L,
respectively.
Overall, customers have noticed that their water has improved in clarity and taste of their
water, possibly due to the enhanced coagulation, and decreased chlorine demand combined with
diligent attention to water quality throughout the system.
Simultaneous Compliance Guidance Manual B-8 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
Lessons Learned From this Case Study
• Source water testing and the development of treatment plant and distribution system
profiles helped the systems identify the factors that were causing DBF formation;
• By adjusting coagulation methods and the point of chlorination, while optimizing
distribution operations to optimize booster chlorine use, these small surface water
systems succeeded at reducing TTHM and HAAS in the combined system, even when
using a challenging source water;
• Compliance with TTHM and HAAS standards can be achieved, without negatively
impacting other regulatory programs, by implementing a combination of several
carefully planned and monitored operational changes; and
• Water quality improvements can be realized with short-term operational changes, and
provide information useful in decision-making, pending completion of more costly,
time-intensive, long-term modifications.
Further Reading
Readers can find more information about this case study in the following publications:
Routt, J.C. 2004. Lowering DBFs in Combined Systems. Opflow. 30(4): 1-7.
Routt, J.C. and N.G. Pizzi 2000. Kentucky-American Water's Cooperative, Step-wise
Process of Assisting Two Small Contiguous Systems in Complying with Pending D/DBP
Requirements. In Proceedings of A WWA Water Quality Technology Conference.
Simultaneous Compliance Guidance Manual B-9 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix B. Case Studies
This page intentionally left blank.
Simultaneous Compliance Guidance Manual B-10 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
Case Study #2
Modifying pH During Chlorination
Public Utility District #1
Skagit County, Washington
This case study provides an example of how a PWS used pH depression to reduce DBFs.
The depression of pH via carbon dioxide (CCh) injection ahead of the fiocculation basins also
produced the following results:
1) Increased coagulation efficiency and removal of DBF precursors;
2) Increased CT throughout the treatment plant, allowing for reduced chlorine injection;
and
3) Increased and stabilized pH levels in the distribution system by increasing the
buffering capacity following caustic soda addition.
The information for this case study came from Friedman and Hamilton (1997). Readers
should refer to that reference for further information.
Introduction
Public Utility District #1 of Skagit County (the District) is located in the northwest sector
of Washington State, approximately 70 miles south of the Canadian border and 70 miles north of
Seattle. The District's source of supply is Judy Reservoir, which is fed by several streams
originating in the Cultus Mountain watershed in Sedro-Woolley, WA. The District operates a
water filtration plant (WFP) designed to provide an original nominal/hydraulic flow of 12/18
million gallons per day (MOD) with an ultimate capacity of 21/36 MOD. Exhibit B.I provides a
summary of typical water quality parameters.
Exhibit B.1 Summary of Historical Source Water Quality Data
Parameter
Conductivity
Temperature
PH
Alkalinity
Hardness
Dissolved Oxygen
TOC
Turbidity
Units
mhos/cm
°C
standard units
mg/L as CaCOs
mg/L as CaCOs
mg/L
mg/L
NTU
Range of Values
30-60
1-21
6.9-7.5
14-16
8.6-21.6
9-13
3.0-7.0
0.25-1.5
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
B-ll
March 2007
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Appendix B. Case Studies
In the late 1980s, the District faced several source water quality issues. The TOC in the
Judy Reservoir supply ranged from 3 to 7 mg/L, leading to high formation of DBFs upon
chlorination. The District was having difficulty meeting CTs year-round, especially during the
colder months. The Judy Reservoir supply is soft and poorly buffered, with alkalinity levels
between 14-16 mg/L as CaCOs, and the District exceeded the lead action level under the LCR.
The Original Treatment Process at Judy Reservoir
Before changes were made, initial oxidation/ disinfection was provided by chlorine
dioxide, primarily to oxidize manganese which is present in the 0.2-0.3 mg/L range. Coagulants
consisting of hybrid aluminum salts and a polyquaternaryamine were used. Direct filtration was
conducted with a slight addition of a mild anionic filter aid. The filter media consisted of one
foot of silica sand and two feet of anthracite coal. Typical flows were 6000 gpm (8.6 mgd) in
the winter and 11,800 gpm (17 mgd) in the summer with 2000 square feet of available filter
surface area. Chloramination was used for secondary disinfection.
Simultaneous Compliance Issues Faced by the Utility
The District was having difficulty meeting CTs required by the SWTR. To address this
problem, free chlorine was historically applied ahead of the fiocculation basins to increase CTs.
However, TOC levels in the Judy Reservoir led to high formation levels of DBFs upon
chlorination. This situation created difficulty for the District in complying with the Stage 1
D/DBPR. Exhibit B.2 shows the historical relationship between inactivation ratio (calculated CT
divided by required CT) and TTHM formation.
Simultaneous Compliance Guidance Manual B-12 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
Exhibit B.2 Inactivation Ratio vs. TTHM Plant Effluent
6-Jan-94 12-M-95
Date
Using existing treatment methods, CTs could not be met consistently without
significantly increasing DBFs. Thus, a method other than increasing chlorine and contact time
was needed to achieve higher inactivation ratios. Methods of decreasing pH levels throughout
the treatment train were therefore considered. Because the District used direct filtration (rather
than conventional filtration), they were not required to meet TOC removal criteria under the
Stage 1 D/DBPR. However, lowering the pH at the beginning of the treatment train would have
the added benefit of enhancing coagulation, increasing the removal of DBF precursor materials.
Simultaneously, the District was having difficulty complying with the LCR; the 90th
percentile lead level was 0.049 mg/L at a finished water pH of approximately 7.3. The pH was
raised to 8.0 but the lead action level was still exceeded. Electrochemical corrosion testing was
conducted to compare the corrosion control effectiveness of pH adjustment and orthophosphate
addition for lead containing surfaces. The greatest reductions in corrosion rate were observed
when the pH was raised to 8.5, or when the pH was raised to 8.0 and 4 mg/L (as PO^) were
added. Due to a number of functional constraints, the District did not want to add phosphates to
the water supply. Thus, the decision was made to increase pH to the range of 8.5 to 9.0.
Like most surface water supplies in the Pacific Northwest, the District's Judy Reservoir
supply is very soft and poorly buffered. Alkalinity levels are between 14-16 mg/L as CaCOs.
To maintain the desired pH range of 8.5 to 9.0 throughout the distribution system, alkalinity
increases would also be required.
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
B-13
March 2007
-------
Appendix B. Case Studies
Steps Taken by the Utility
The District injected CC>2 prior to the flocculation basins in addition to at the end of the
treatment train where caustic soda is added. The advantages of adding carbon dioxide ahead of
the flocculation basins were three-fold:
1) The associated pH depression increased coagulation efficiency to remove DBF
precursors;
2) The associated pH depression increased CTs throughout the treatment plant, allowing
chlorine injection to be reduced; and
3) Subsequent pH increases using caustic soda provided finished water with increased
alkalinity levels and, increased buffering capacity.
The chemistry of CC>2 is well understood and is used extensively throughout the water
and wastewater industry. However, use of CC>2 for WTP process control in the Pacific
Northwest was fairly uncommon. The stoichiometry of CC>2 addition in the pH range of 6.0 to
10.0 is outlined below.
CO2 + H2O —> H2CO3 (carbonic acid)
H2CO3 —> H+ + HCO3" (bicarbonate)
Over the pH range of 6.0-10.0, the dissociation of carbonic acid in water depresses the pH and
adds bicarbonate, which is the primary contributor to alkalinity.
CC>2 feed was set up at two locations within the District's treatment facility: 1) ahead of
the flocculation basins and 2) at the plant effluent. CC>2 injection began on a trial basis during
March, 1995. 24-144 Ib/d (2 mg/L) were injected ahead of the flocculation basins (depending on
plant flow), and 192 Ib/d (3 mg/L) were injected after filtration. The target pH level ahead of the
flocculation basin was less than 6.5. Additional CC>2 was required prior to caustic soda addition
to raise the alkalinity of the finished water to 25 mg/L as CaCO3.
Results of the Steps Taken
Effects on DBF Formation
With the depression of pH and resulting increased coagulation efficiency, the percent of
TOC removal increased from an average of 25 percent to approximately 40 percent. The mass of
TOC removed nearly tripled from 1 mg/L to 2.5-3 mg/L. The percent and mass of TOC
removed before and after CO2 injection are shown in Exhibit B.3. Thus, even a small decrease in
pH (from 6.9 to 6.6) during coagulation and flocculation has significantly enhanced coagulation.
Exhibit B.3 shows the percent and max of TOC removed after CO2 injection was initiated
in March 1995. During the first few months, CO2 was fed on a trial basis using a temporary feed
system that restricted the amount of CO2 that could be added. Thus, initial decreases in TOC
removal were observed until the system stabilized.
Simultaneous Compliance Guidance Manual B-14 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
TTHM formation within the treatment train was reduced by approximately 33 percent.
Observed decreases in TTHM formation can be attributed to enhanced TOC removal, reduced
chlorine levels, and to the fact that less TTHMs are formed at lower pH levels. Prior to CC>2
addition, HAAS levels in the plant effluent ranged between 40-60 ug/L when TOC levels were
between 3-5 mg/L. After CO2 addition, HAAS levels in the plant effluent decreased to the range
of 35-45 ug/L even though raw water TOC levels were in the range of 5-7 mg/L.
Exhibit B.3 TOC Removal vs. Time
% Removed
mg/L Removed
3/30/94 10/18/94 3/20/95
Date
11/29/95
Effects on CT Compliance
CT credit decreases as temperature, disinfectant concentration, and contact time decrease.
CT credit using chlorine increases as pH decreases. Since DBF formation was a concern for the
District, the best way to increase CT credit without forming additional DBFs was to lower the
pH.
It is difficult to show actual improvements in the District's CT compliance as a result of
CO2 addition since disinfectant dosages, plant throughput (i.e., contact time) and temperature
vary from month to month. However, the impacts of depressing the pH by 0.5 units are outlined
in terms of required chlorine dose and required contact time in Exhibit B.4.
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
B-15
March 2007
-------
Appendix B. Case Studies
Exhibit B.4 Impacts of CO2 Injection on CTs
Effect of pH on Required Free Chlorine Dosages
pH
7.0
6.5
6.0
Contact Time (min)
82.5
82.5
82.5
Required Free Ch (mg/L)
2.0
1.67
1.41
Effect of pH on Required Contact Time
pH
7.0
6.5
6.0
Contact Time (min)
82.5
69
58
Required Free Ch (mg/L)
2.0
2.0
2.0
Thus, the same CT can be achieved with less chlorine. Alternatively, higher flows can be
accommodated without increasing chlorine dosages. It should be noted that in addition to
considering impacts of reduced chlorine dosages on CT, utilities must consider other drivers for
determining chlorine dose, such as the ability to maintain a disinfectant residual throughout the
distribution system. Because Skagit PUD#1 chloraminates, they are able to maintain a stable
residual despite fluctuations in chlorine dosage at the head of the treatment plant.
Effects on Corrosion Control Treatment
Distribution system water quality sampling suggested that pH and alkalinity levels are
more uniform throughout the system. Alkalinity levels have nearly doubled (from 14 mg/L as
CaCOs to 25 mg/L as CaCOs), resulting in more stable water with respect to pH and corrosion
control. Prior to CC>2 injection, the District would raise the pH of the finished water to 8.0, but it
would decrease to 7.4 at many locations within the distribution system. Follow-up LCR
monitoring conducted by utilities across the U.S. has shown that providing consistent and stable
pH/ alkalinity levels can be essential to controlling lead levels at the tap. The District found that
nearly a year of CC>2 injection has to pass before pH levels stabilized within the distribution
system.
Lead levels at the tap decreased substantially at most of the "high lead" homes in the
District. The 90th percentile lead level was 0.004 mg/L during the last round of monitoring
conducted in 2003. It is likely that increased alkalinity helped to decrease lead levels by two
different mechanisms: 1) providing stabilized pH levels at the tap; and 2) increasing carbonate
levels to aid in the formation of more stable lead carbonate passivating films.
A study was undertaken by the District to determine whether elevated lead levels
measured at the tap were in the soluble or particulate form. It was found the lead was primarily
in the particulate form. When the pH was adjusted to 8.0 without alkalinity adjustment, elevated
lead levels were mostly due to particulate lead (particulate being the difference between total and
soluble lead), suggesting that stable lead carbonate films were not forming. After the pH was
further increased and the alkalinity was doubled, total lead concentrations decreased as shown
for three sampling locations in Exhibit B.5. Although lead solubility theoretically decreases as
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
B-16
March 2007
-------
Appendix B. Case Studies
pH increases to a maximum of 9.5, alkalinity adjustment may also be necessary to address the
particulate lead fraction.
Exhibit B.5 Total vs. Soluble Lead
Lead Action Level = 0.015
| Total Lad - pH 8.0-Dec 93
• Total Lead-pH 9.0-Apr 96
D Soluble Lead - pH 9.0 - Apr 9
63
Sample Location
Implementation and Operational Issues Faced by the Utility
CC>2 does not solubilize instantaneously, and therefore a pressurized solution feed system
was required. In this system, the CC>2 is injected to a pressurized side stream forming carbonic
acid. The carbonic acid solution is readily solubilized by the receiving water and is injected
directly into the pipeline.
Chemical costs for caustic soda doubled once CC>2 was injected since twice as much
caustic was required to raise the pH to 8.5-9.0. Considering the multiple benefits the District is
experiencing, a chemical cost increase of $30,000 per year or $10 per million gallons treated was
relatively inexpensive. The capital cost of the permanent CC>2 system was $15,000 (1996
dollars).
Lessons Learned From this Case Study
• It is possible to achieving both greater Ct and TOC removal by reducing pH during
treatment;
• pH reduction can in some cases be achieved through CC>2 injection; and
• CC>2 injection at multiple locations during treatment may enhance benefits compared
to injection at the end of treatment only for pH control purposes.
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
B-17
March 2007
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Appendix B. Case Studies
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Simultaneous Compliance Guidance Manual B-18 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix B. Case Studies
Case Study #3
Pre-sedimentation
Kansas City Water Services
Kansas City, Missouri
This case study provides an example of how Kansas City's existing pre-sedimentation
basins may help to achieve compliance with the upcoming regulations.
Kansas City's pre-sedimentation basins were constructed prior to development of the
DBPRs and ESWTRs, but still provided a benefit with respect to regulatory compliance. These
pre-sedimentation basins have the potential to assist in providing the following benefits:
• TOC reduction required under the Stage 1 D/DBPR due to coagulation in the basins;
• Turbidity reduction necessary for compliance with the ESWTR; and
• 0.5-log treatment credit for removal of Cryptosporidium (if needed to comply with
the LT2ESWTR.
Under the LT2ESWTR, systems are required to collect their source water samples prior
to chemical treatment, such as coagulation, oxidation, and disinfection, for the purpose of
determining their bin classification. Kansas City applies treatment chemicals (coagulants,
potassium permanganate, lime) to the pre-sedimentation basins and must therefore collect
samples for LT2ESWTR monitoring prior to the basins. However, Kansas City is eligible for a
0.5-log Cryptosporidium treatment credit for the pre-sedimentation basins if the basins can
achieve a monthly mean reduction of 0.5 log in turbidity.
Both the LT2ESWTR sampling location and the Stage 2 D/DBPR treatment plant point-
of-entry are considered to be the influent to the pre-sedimentation basins. However,
simultaneous compliance issues associated with pre-sedimentation basins include the potential
for algae blooms, which can increase disinfection by-product formation at the plant effluent.
This case study was developed using information available from staff at Kansas City
Water Services.
Introduction
The Kansas City, Missouri drinking WTP, which was originally constructed in the 1920s,
is rated for 240 MOD. The source water comes from the Missouri River and wells under the
influence of the Missouri River. The treatment process involves pre-sedimentation, excess lime
softening, recarbonation, filtration, and stabilization.
Due to the turbidity levels of the Missouri River, the pre-sedimentation basins are a
critical step in the City's WTP processes. The turbidity of the untreated source water is quite
variable, averaging 114 nephelometric turbidity units (NTU) in 2002, 185 NTU in 2003, and 318
NTU in 2004. The untreated water turbidity can exceed 5,000 NTU. The turbidity of the
untreated source water was even higher and more variable when the plant was built. However,
the construction of several upstream dams during the 1960's resulted in lower turbidity levels at
the City's intake. In addition, the pre-sedimentation basins serve to reduce the amount of solids
entering the softening process.
Simultaneous Compliance Guidance Manual B-19 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix B. Case Studies
The plant was constructed well before the Safe Drinking Water Act (SDWA) and
subsequent drinking water regulations came into effect. Therefore, the pre-sedimentation basins
were not designed to meet compliance issues as much as they were needed as part of the water
treatment process. However, as the treatment regulations evolved, the pre-sedimentation basins
helped the plant meet new regulations.
The Treatment Process at the Kansas City, Missouri WTP
Today there are 6 pre-sedimentation basins, each with a detention time of about 4 hours
at 40 MOD. Each pre-sedimentation basin is approximately 200 feet in diameter and has an 80-
foot diameter fiberglass ring installed that is approximately half the height of the basin. This
fiberglass ring serves as a mixing area for the coagulation chemicals to react. There are four
mixers in each pre-sedimentation basin. These mixers and the capability for chemical injection
were added to the pre-sedimentation basins in the 1970s. Lower source water turbidity levels
resulted in reduced solids loading to the pre-sedimentation basins and increased colloidal
materials, impacting the efficiency of the pre-sedimentation basins for removing turbidity.
Therefore, the mixing areas and chemical feed capabilities were added. However, the solids
removal capacity of the basins remained the same.
Role of Pre-sedimentation Basins in Regulatory Compliance
Kansas City's pre-sedimentation basins could be used to lower turbidity as part of
compliance with the Surface Water Treatment Rules (SWTRs). Additionally, compliance with
the Stage 1 D/DBPR requires removal of TOC from source water to reduce the formation of
DBFs. Pre-sedimentation basins may serve to remove a portion of the TOC. Kansas City can
receive a 0.5-log Cryptosporidium reduction credit for the pre-existing pre-sedimentation basins
because the basins may assist in removing Cryptosporidium from the source water. Kansas City
is required to monitor the influent of their pre-sedimentation basins to determine their
Cryptosporidium bin classification.
Simultaneous Compliance Issues Faced by the Utility and Steps Taken
Algae may grow in the pre-sedimentation basins, which could contribute additional NOM
and result in the formation of DBFs, affecting compliance with the DBF Rules. Kansas City has
managed to avoid this simultaneous compliance issue by minimizing algae blooms through
potassium permanganate addition in the pre-sedimentation basins. Additionally, the velocity of
the water in the pre-sedimentation basins is kept high by the mixers. In the rare instance that
algae is observed, it is minimal and typically resides around the sides of the pre-sedimentation
basins. Additionally, the pre-sedimentation basins are followed by an excess lime softening step,
during which pH levels are raised above 10 units, reducing the potential for algae growth in this
step.
Implementation and Operational Issues Faced by the Utility
The pre-sedimentation basin improvements allow the plant to add a variety of treatment
chemicals to control turbidity of the pre-sedimentation basin effluent. The water plant has the
capability of feeding ferric sulfate, polymer, and potassium permanganate to these basins. The
Simultaneous Compliance Guidance Manual B-20 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix B. Case Studies
turbidity of the pre-sedimentation basin effluent is controlled based on the economics of the
treatment plant operations. By adding different coagulation chemical concentrations and
combinations, the turbidity exiting the pre-sedimentation basis can be reduced to below 10 NTU.
The plant uses factors such as lime dose requirements to determine the optimal treatment in the
pre-sedimentation basins. This is because higher turbidity water entering the softening basins
usually has more colloidal material, which in turn requires more lime to provide the desired
softening because of the competing reactions between the charges stabilizing the colloids and the
calcium carbonate precipitation process. Thus, the cost of the coagulant dosage to obtain a
certain turbidity from the basins is compared to the cost of the lime required to provide the
desired softening and an economic balance is found.
The plant reports that 80-90 percent of the time, potassium permanganate is sufficient for
addressing operational issues such as taste and odor control and turbidity control. The remainder
of the time, ferric sulfate is able to maintain the plant's operation.
To receive a treatment credit for Cryptosporidium removal under LT2ESWTR (if
needed), Kansas City will need to evaluate the effectiveness of the dosages in reducing turbidity,
and assure that a monthly mean reduction of 0.5-log turbidity is achieved to receive the 0.5-log
Cryptosporidium treatment credit.
Lessons Learned From this Case Study
The following lessons were learned from Kansas City's experience with pre-sedimentation
basins:
• The pre-sedimentation basins reduce the effects of large and variable turbidity
episodes;
• Improving the pre-sedimentation basins to incorporate chemical treatment and mixing
allowed the pre-sedimentation basins to become more useful in water treatment
operations by allowing the plant to control turbidity entering the softening basins as
well as assisting in removing TOC and DBF precursors;
• The potential drawbacks of pre-sedimentation basins such as increased NOM from
algae are minimized through operations; and
• Utilities that apply treatment chemicals to their pre-sedimentation basins will need to
designate a sampling location prior to the pre-sedimentation basins for
Cryptosporidium monitoring under the LT2ESWTR. This location may be the same
as the point of entry already used for compliance with other regulations.
Simultaneous Compliance Guidance Manual B-21 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix B. Case Studies
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Simultaneous Compliance Guidance Manual B-22 March 2007
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Appendix B. Case Studies
Case Study #4
Switching Coagulants
Hillsborough River Water Treatment Plant
Tampa, Florida
This case study describes how a system could simultaneously comply with the TOC
removal requirements of the Stage 1 D/DBPR and the turbidity removal requirements of the
IESWTR. Enhanced coagulation is a best available technology (BAT) for TTHM precursor
removal for the Stage 1 D/DBPR.
Introduction
The City of Tampa, Florida, operates a 100 MOD conventional treatment plant (the
Hillsborough River Water Treatment Plant, HRWTP). The HRWTP uses the Hillsborough River
as its source water. The plant, built in 1924, currently serves over 450,000 people. In 1991, it
switched from enhanced coagulation with alum to enhanced coagulation with ferric sulfate. The
influent surface water has high TOC and is subject to large seasonal variations. By switching
coagulant, the HRWTP's operators expected to satisfy requirements of the Stage 1 D/DBPR.
They had investigated the feasibility of enhanced coagulation with ferric sulfate before the Stage
1 D/DBPR became a regulatory requirement. They found that enhanced coagulation with ferric
sulfate not only increased TOC removal significantly, but also reduced turbidity levels in the
finished water.
A summary of the influent water quality is provided in Exhibit B.6.
Exhibit B.6 Influent Water Quality at HRWTP
Water Quality Parameters
TOC (mg/L)
Minimum
Average
Maximum
Turbidity (NTU)
Minimum
Average
Maximum
PH
Minimum
Average
Maximum
Alkalinity (mg/L as CaCO3)
Minimum
Average
Maximum
Influent1
4.3
13
26
1.2
2.1
40
6.8
7.6
8.5
42
93
143
Notes: 1. Data from an Information Collection Rule (ICR) sample collection from July 1997 •
December 1998
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
B-23
March 2007
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Appendix B. Case Studies
The Original Treatment Process at HRWTP
Exhibit B.7 shows a schematic of the treatment process at HRWTP prior to converting to
ferric sulfate. Raw water was treated with potassium permanganate for taste and odor control.
Enhanced coagulation was implemented using alum (range of alum dose = 50 - 200 mg/L,
average dose = 120 mg/L), at an average pH of 5.7 (range 4.9 - 6.6). An organic polymer was
added to enhance the flocculation process. Primary disinfection was attained by applying
chlorine just prior to the filters. After filtration, more chlorine and ammonia were added to form
chloramines for residual disinfection. The pH of the finished water was increased to around 7.6
with caustic soda and soda ash in the blending chamber, to meet a Langelier Index goal of+/-0.2.
Exhibit B.7 Treatment at the HRWTP Prior to Implementing Enhanced Coagulation
Potassium
Permanganate
Alum +
Polymer
Lime
Chlorine +
Ammonia
Raw River
Water
Caustic Soda +
Soda Ash
Blending
Residuals Thickening j
Residuals Processing
Distribution
System
Simultaneous Compliance Issues Faced by the Utility
In order to reduce DBP precursors and TTHM and HAAS concentrations, the City of
Tampa decided to switch to enhanced coagulation with ferric sulfate, enhancing TOC removal
and consequently lowering the DBP formation potential.
Successfully enhancing coagulation to improve TOC removal can affect particle and
pathogen removal effectiveness. The system was concerned that, at lower pH, the higher
coagulant dose conditions for enhanced coagulation could result in particle re-stabilization and
an increase in settled water turbidity, leading to non-compliance with the IESWTR. Increased
settled water turbidity could also impact the system's ability to receive Cryptosporidium removal
credit for enhanced filter performance. Variability in source water quality presented a further
challenge to the operators who were attempting to optimize particle and TOC removal with a
new coagulant.
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBP Rules
B-24
March 2007
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Appendix B. Case Studies
Steps Taken by the Utility
Tampa implemented enhanced coagulation with ferric sulfate to improve TOC removal.
At the same time, it applied BMPs to ensure that filter effluent turbidity would not be adversely
affected. These included flow-pacing the coagulant feed and conducting additional jar tests to
ensure that coagulant overdosing did not occur.
Exhibit B.8 shows a schematic of the treatment process at HRWTP after the system
changed to enhanced coagulation with ferric sulfate. Raw water continues to be treated with
potassium permanganate for taste and odor control. Enhanced coagulation uses ferric sulfate
(range dose = 40 - 300 mg/L, average dose = 140 mg/L), at an average pH of 4.0 (range 3.5 -
4.8). The low coagulation pH is attained by adding sulfuric acid. An organic polymer is added
to enhance the flocculation process. The settled water is treated with lime for partial pH
adjustment. The residuals are thickened and then pumped to a residuals processing facility for
further dewatering, processing, and disposal. Primary disinfection is attained by adding chlorine
to the settled water to produce a free residual of 1-2 mg/L just prior to the filters. After filtration,
ammonia and chlorine are added to form chloramines. The finished water combined disinfectant
residual ranges from 3 - 4.5 mg/L of monochloramine. The pH of the finished water is adjusted
to around 7.6 with caustic soda and soda ash in the blending chamber, to meet a Langelier Index
goalof+/-0.2.
Exhibit B.8 Treatment at the HRWTP After Implementing Enhanced Coagulation
Ferric Sulfate +
Polymer +
Potassium Sulfuric Acid
Permanganate
Lime
Chlorine +
Ammonia
Raw River
Water
Caustic Soda +
Soda Ash
Blending
Distribution
System
Beneficial Re-use
To ensure that excessive coagulant dosing doesn't occur, the operators check the
coagulant dose regularly with jar tests. The operators also ensure that coagulant feed is flow
paced. These practices help ensure that turbidity requirements are not violated.
Simultaneous Compliance Guidance Manual B-25 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix B. Case Studies
Results of the Steps Taken
• TOC removal - Finished water TOC removal with enhanced alum coagulation ranged
from 21 to 50 percent. For enhanced coagulation with ferric sulfate, TOC removal
ranges from 70 to 88 percent, with an average of 81 percent. This is well beyond the
minimum TOC removal requirements of the Stage 1 D/DBPR (based on the source
water TOC and alkalinity concentrations). Influent and effluent water quality is
shown in Exhibit B.9. Thus, enhanced coagulation with ferric sulfate is much more
effective than enhanced coagulation with alum for removing DBF precursors;
• TTHM reduction - Before the changes in the coagulation practice, the finished water
TTHM ranged from 27 - 111 //g/L, with an average of 59 //g/L (Exhibit B.9). After
the treatment modifications (from July 1997 through December 1998), the finished
water TTHM ranged from 47 - 67 //g/L, with an average of 60 //g/L. Enhanced
coagulation with ferric sulfate seems more effective than coagulation with alum at
removing DBF precursors (i.e., TOC), when the raw water is high in TOC. This is
reflected by the lower maximum level of TTHM measured after treatment
modifications (i.e., the maximum trihalomethane (THM) concentration was reduced
from 111 to 67 //g/L). The new treatment approach reduced THMs by increasing
TOC removal and chlorinating at a lower pH. Implementing enhanced coagulation
with ferric sulfate has enabled HRWTP to achieve compliance with the Stage 1
TTHM MCL of 80 //g/L; and
• Turbidity - As can be seen clearly from Exhibit B.9, enhanced coagulation with ferric
sulfate was more effective than alum coagulation at reducing turbidity in the finished
water. Enhanced coagulation with ferric sulfate was able to achieve the IESWTR
turbidity requirements more easily and consistently.
Simultaneous Compliance Guidance Manual B-26 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix B. Case Studies
Exhibit B.9 Finished Water Quality Before and After Implementing Enhanced
Coagulation with Ferric Sulfate
Water Quality
Parameters
TOC (mg/L)
Minimum
Average
Maximum
Turbidity (NTU)
Minimum
Average
Maximum
PH
Minimum
Average
Maximum
Alkalinity (mg/L
as CaCO3)
Minimum
Average
Maximum
TTHM 0/g/L)
Minimum
Average
Maximum
HAAS (//g/L)
Minimum
Average
Maximum
Influent1
4.3
13
26
1.2
2.1
40
6.8
7.6
8.5
42
93
143
NA
NA
Finished Water
Before implementing
Enhanced
Coagulation2
1.8
6.2
8.9
0.04
0.32
1.13
7.1
7.6
8.2
80
122
187
27
59
111
NDC
After implementing
Enhanced
Coagulation3
1.6
2.9
5.1
0.04
0.11
0.28
7.2
7.6
7.7
48
92
125
47
60
66
32
47
66
Notes:
1. Data from ICR sample collection from July 1997 - December 1998
2. Data collected for calendar year 1990.
3. Data collected for calendar year 1997; ICR data from July 1997 - December 1998 was used for organic
analysis.
4. NDC = No Data Collected
5. NA = Not Applicable
Implementation and Operational Issues Faced by the Utility
• Operator training and start-up - It took around 6 months for the operational staff to
be comfortable with implementing enhanced coagulation, and nearly a year for the
treatment plant to operate like an integral unit. The treatment strategy did not
significantly change the operational needs of the plant and no additional staff were
added;
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
B-27
March 2007
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Appendix B. Case Studies
• Controlling manganese - The only major problem experienced in implementing the
treatment modification was the control of manganese. The lower pH required for
enhanced coagulation with ferric sulfate, relative to alum coagulation, allowed
dissolved manganese to pass through the filters. The issue was resolved by
maintaining the pH on top of the filters at greater than 6.0; and
• Corrosion due to acid addition - The addition of sulfuric acid promoted corrosion
in the rapid-mix chamber at the feed diffuser. The problem was resolved when the
utility found a suitable coating for their rapid-mix chamber. The coating used was
a two-part commercial membrane applied at 60 wet mils, using an air-supplied
mastic air gun. After application, the coating required a 7-day curing period
before the basin could be put back into service. The settling basins were epoxy-
coated and did not experience any corrosion.
Lessons Learned From this Case Study
• Enhanced coagulation with ferric sulfate can achieve the multiple objectives of
increased TOC removal and improving reductions in finished water turbidity without
significantly changing the operational needs of the plant; and
• One key to successfully implementing enhanced coagulation is to ensure that
excessive coagulant dosing does not occur. This results in turbidity breakthrough at
the filters, resulting in potential non-compliance with the IESWTR. One way to
achieve this is by conducting additional jar tests and flow-pacing the coagulant feed
when plant water flows are variable.
Simultaneous Compliance Guidance Manual B-28 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix B. Case Studies
Case Study #5
Enhanced Coagulation - Problems with Copper Pitting
Washington Suburban Sanitary Commission
Montgomery and Prince Georges County, Maryland
This case study provides an example of negative effects that could possibly be caused by
enhanced coagulation. Washington Suburban Sanitary Commission (WSSC) changed their
coagulation process to reduce filtered water turbidity. This was implemented prior to
development of the Stage 1 D/DBPR and, therefore, not optimized to meet associated
requirements. However, WSSC's experience indicates that coagulation improvements might
have had unintended results in the distribution system. After alterations were made to WSSC's
coagulation process, WSSC customers began reporting pinhole leaks in their copper piping,
possibly caused by a combination of factors. The utility has been unable to determine the exact
cause of the pinhole leaks. In this case study, the primary concerns relate to compliance with:
• LCR
• DBF Rules
While this treatment was implemented prior to the DBF Rules, it does indicate a potential
problem associated with implementing the Stage 1 D/DBPR's required treatment technique using
enhanced coagulation.
This case study was developed using information available from staff at the WSSC and from
their customer care Web site detailing this issue
(http://www.wsscwater.com/copperpipe/pinholescroll.cfm). The cause of pinhole leaks in
WSSC's system continues to be under investigation.
Introduction
The WSSC provides drinking water to 1.6 million people in suburban Maryland. WSSC
relies on two rivers, the Potomac and Patuxent, to supply an average of 167 MG per day. Both
river supplies are treated at separate filtration plants. The Potomac plant treats river supply while
the Patuxent plant treats water from a reservoir system. In the mid-1990s, WSSC made
treatment changes at the Potomac plant to enhance filtration performance, including changing
filtration media and changing coagulant, from ferric chloride to polyaluminum chloride. During
the 1990s, coagulant doses were increased slightly at the Patuxent plant, which used alum most
of the time, occasionally switching to ferric chloride during the winter.
The primary reasons WSSC made these treatment changes were:
• Prevention of waterborne pathogen outbreaks - A large-scale cryptosporidiosis
outbreak occurred in Milwaukee, Wisconsin in 1993. The outbreak coincided with
elevated effluent turbidity levels. Studies of the causes and prevention methods
indicated that coagulation and filtration performance are critical in preventing the
entry of Cryptosporidium to the distribution system; and
Simultaneous Compliance Guidance Manual B-29 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix B. Case Studies
• Partnership for Safe Water - This is an industry program, supported by EPA and
AWWA, that focuses on protecting drinking water customers from microbial
contaminants. WSSC has participated in this program that includes meeting stringent
criteria for turbidity in filtered drinking water.
While WSSC's coagulation changes were not optimized for compliance with the Stage 1
D/DBPR, WSSC did observe lower TOC levels in effluent at the Potomac WTP.
The Original Treatment Process at WSSC's WTPs
Both the Potomac and Patuxent Treatment Plants include similar treatment processes:
• Coagulation and fiocculation
• Sedimentation
• Filtration
• Fluoridation
• Lime addition for corrosion control
• Chlorination
Simultaneous Compliance Issues Faced by the Utility
In 1998, WSSC began receiving complaints from customers that pinhole leaks were
developing in their copper piping. As of December 2004, almost 5,500 customers have reported
this problem. Pinhole leaks have occurred in areas served by both drinking water supply
sources. WSSC has collected data on pinhole leaks from customers and these trends have been
apparent:
• Many pinhole leaks are in cold water horizontal copper piping
• Many leaks are located in older portions of service area
• Almost 80 percent of leaks have occurred in homes built before 1970
In 2000, WSSC formed a task force to study the pinhole leaks and possible causes. The
task force included WSSC staff, copper and plumbing industry experts, and corrosion experts.
The researchers conducted bench-scale experiments with copper piping and simulated drinking
water and determined that a combination of high pH, aluminum solids, and chlorine levels, and
no remaining NOM caused significant pitting on copper piping in about one month (Marshall,
Rushing and Edwards 2003).
NOM present in drinking water supplies is a DBP precursor and is typically removed
through filtration or coagulation. TOC levels usually correspond to the presence of NOM in
drinking water. The presence of NOM in the distribution system was previously thought to
prevent, to some extent, corrosion of piping materials, such as cement, iron, and copper. The
research by Marshall, Rushing and Edwards (2003) contradicts previous understanding of
NOM's role in copper corrosion.
Simultaneous Compliance Guidance Manual B-30 March 2007
For the Long Term 2 and Stage 2 DBP Rules
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Appendix B. Case Studies
Water quality conditions in WSSC's distribution system that may have contributed to pinhole
leaks in copper piping include:
• Aluminum - Since 1995, both treatment plants have used an aluminum-based
coagulant. Finished water aluminum levels are relatively low. The average Potomac
WTP residual levels range from 0.046 mg/L to 0.060 mg/L, and at Patuxent WTP,
which recently switched from alum to polyaluminum chloride, average effluent
aluminum levels are 0.030 mg/L (Edwards et al. 2004). In comparison, the national
average for effluent aluminum levels is 0.090 mg/L. Sampling in WSSC's
distribution system indicated that aluminum levels increased after treatment to levels
higher than 0.065 mg/L total aluminum. Researchers indicate that high aluminum
samples were collected in areas near recently cleaned or re-lined piping (Edwards et
al. 2004). A forensic analysis of WSSC failed copper piping showed that aluminum
deposits were frequently present (Marshall, Rushing and Edwards 2003);
• Chlorine - WSSC, like the majority of utilities, uses chlorine to provide a disinfectant
residual in the distribution system;
• pH - WSSC increases the pH of water entering their system during the treatment
process for corrosion control. Water from the Potomac WTP has a pH of about 7.5 in
the distribution system. Until recently, the Patuxent WTP had a pH of about 8.2 in
the distribution system (now adjusted to about 7.5 since orthophosphate addition
began); and
• TOC - The Potomac WTP achieves approximately 40 percent TOC removal, which is
a slight increase since the coagulant and filter media change. Patuxent reservoir
water has a lower level of NOM, with treated water TOC levels below 2 mg/L. TOC
removal at the Patuxent WTP has not changed.
StepsTaken by the Utility
In late 2003, WSSC implemented orthophosphate addition to both treatment plants.
Addition was phased in slowly with the dose reaching a level of 1 mg/L (as PO
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Appendix B. Case Studies
Implementation and Operational Issues Faced by the Utility
WSSC experienced the following issues when implementing orthophosphate addition:
• Increased wastewater phosphorus resulted in increasing cost for wastewater
treatment;
• WSSC investigated the potential for orthophosphate addition to increase discolored
water complaints due to iron release from unlined cast iron mains; and
• During summer conditions, turbidity of finished water (i.e., following post-filter lime
addition) has increased occasionally after orthophosphate addition. WSSC is still
investigating the cause.
Lessons Learned From this Case Study
• Switching coagulant may have unintended consequences on water quality;
• The role of NOM in copper corrosion control needs to be better understood by the
drinking water industry;
• The synergistic effects of chlorine and aluminum at pHs that have been optimized for
corrosion control also need to be better understood by the drinking water industry.
These interactions can be exacerbated for utilities that use free chlorine; and
• Pilot-scale and/or electro-chemical testing for determining the impacts of chemicals
on corrosion control were useful in identifying an appropriate solution.
References
Edwards, M., J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole
leaks in residential plumbing. Water Science and Technology. 49(2): 83-90.
Marshall, B., J. Rushing, and M. Edwards. 2003. Confirming the role of aluminum solids
and chlorine in copper pitting corrosion. In Proceedings of A WWA Annual Conference.
Denver: AWWA.
Rushing, J.C. and M. Edwards. 2002. Effect of aluminum solids and chlorine on cold
water pitting of copper. In Proceedings of AWWA Water Quality Technology Conference.
Simultaneous Compliance Guidance Manual B-32 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix B. Case Studies
Case Study #6
Enhanced Coagulation - Managing Radioactive Residuals
Allen Water Filtration Plant
Englewood, CO
This case study presents a discussion of a system's options for disposing of
radioactive residuals resulting from enhanced coagulation. Enhanced coagulation is
practiced at the system to meet the requirements of the Stage 1 D/DBPR. Uranium is
naturally occurring in the City's source water, but radionuclide levels in the raw water do
not warrant treatment for removal. The radionuclides become concentrated in the residuals
as a result of the enhanced coagulation process at levels that require special considerations
for regulatory approval of sludge disposal.
Introduction
The City of Englewood Allen WFP is a conventional treatment plant with an average
treated flow of 8.5 mgd (design flow of 28 mgd) to serve a population of 48,000 people. The
primary raw water supply comes from surface sources, including the South Platte River, Bear
Creek, and water sources diverted from the Western Slope of Colorado. The plant treatment
processes include addition of potassium permanganate, coagulant, and coagulant aid to the
pipeline ahead of the rapid mix. Mixing is followed by three-stage tapered fiocculation and
settling using lamella inclined plates. The water passes through GAC filters prior to chlorine
addition. Chlorine contact time is obtained in the clearwell and ammonia is added after the
clearwell for chloramine disinfectant residual in the distribution system. Sedimentation sludge
and filter backwash water are dewatered by belt press and the filtrate is sent to the backwash
settling lagoon along with the waste backwash water. Decant from the backwash settling lagoon
is returned to the North Reservoir to be recycled to the head of the plant. Recycle goes into the
washwater lagoon (aka backwash settling lagoon) which overflows to an 80 million gallon
reservoir that is used sparingly as source water as it is blended with raw water drawn from other
sources. The approximate recycle return flow is 1.5%. Treatment includes settling of solids in
the lagoon and in the reservoir.
Exhibit B.10 presents source water and finished water quality details. A process
schematic is shown in Exhibit B. 11.
Simultaneous Compliance Guidance Manual B-33 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix B. Case Studies
Exhibit B.10 Typical Water Quality Parameters at Allen WFP
Water Quality Parameter
Turbidity (NTU)
pH (SU)
TOC (mg/L)
Alkalinity (mg/L as CaCO3)
Barium (mg/L)
Selenium (ug/L)
Alpha Emitters (pCi/L)
Beta/Photon Emitters (pCi/L)
TTHM (ug/L)
HAA5s (ug/L)
Raw Water
1.0-12
7.9-8.7
3.5-5.0
55 - 170
*
*
34 + 5
*
*
*
Treated Water
0.10-0.24
7.6-8.4
2.6-3.75
55-150
0.048
0.0077
7.8 + 3.3
10 + 5
34-55
3-21
* If available, levels present in raw water will be added to next draft.
The Allen WFP practices enhanced coagulation to comply with the Stage 1
D/DBPR by the addition of alum with typical doses of 40 - 60 mg/L of alum. Based on the
average plant flow, the production rate of residuals would be expected to be 1632 Ib/day or
302 cy/yr. Recently (2002-2004), residuals production from the backwash pond is
approximately 1600 cy/yr. The current large volume may be a result of catching up on
previous years' storage. City employees are processing residuals from March to November
to make sure the backwash pond does not exceed its capacity.
Exhibit B.11 Allen Water Filtration Plant Schematic
City Ditch I Allen Water Treatment Plant I
Finished Water
Pump Station
Distribution System
Zone I
Zone II
Settled Water
'Plant Headworks Sludge
North Reservoir
Backwash
Settling Lagoon
Waste Backwash
Water
\ 245af l*
\
' l
x
Discharge 002 A Discharge 001 A
To Big Dry Creek
Chlorine
i i
i i
Ammonia
Pump
Station
Beltpress Filtrate
Filter Backwash Water Recycle System
Coagulant Sludge
De-Watering System
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
B-34
March 2007
-------
Appendix B. Case Studies
Residuals Management Prior to Enhanced Coagulation
The City of Englewood has historically disposed of water treatment residuals by
land applying dried residuals at the City golf course. These residuals were mixed with fill
dirt (2:1 ratio fill to residuals) for berm construction with grass cover. This procedure met
the requirements of the Colorado Department of Health and Environment (CDPHE) with
respect to the state's solid waste regulations and the hazardous/radioactive material
regulations. Residuals disposal facilities in Colorado must comply with all Colorado
health laws and with CDPHE regulations and standards. Acceptance criteria for solid
waste disposal include:
• WFP residuals containing any free liquid cannot be accepted for disposal;
• WFP residuals with a pH less than 6.0 cannot be accepted for disposal; and
• WFP residuals with a total alpha activity value exceeding 40 pCi/g of dry solids
require additional CDPHE guidance prior to disposal. The residuals generator
must contact the CDPHE's Radiation Control Division and the Solid Waste
Division for guidance
Colorado drinking water utilities with residuals that have total alpha activity values
exceeding 40 pCi/g have disposed of residuals using landfill disposal, sanitary sewer
discharge, mono fill disposal, and compost amendment with and without approval from
CDPHE.
Liquid residuals discharged to sanitary sewers are not regulated for water treatment
residuals disposal by CDPHE. Acceptance of water treatment residuals is approved by the
sanitary district authority based on impacts to the treatment process from additional flow
and solids loading.
Simultaneous Compliance Issue Faced by the Utility
Since the inception of enhanced coagulation at the Allen WFP, analysis of the
residuals has shown that the total alpha activity exceeds 40 pCi/g, resulting in the
requirement that the City of Englewood must notify CDPHE of disposal plans for the
residuals to comply with state regulations. The City can no longer dispose of residuals as
has been done in the past because CDPHE no longer allows land application at the golf
course. The concentrated residuals are considered technologically enhanced naturally
occurring radioactive materials (TENORM). Regulation of TENORM in drinking water
residuals is not clearly spelled out in Federal or state regulations.
Steps Taken by the Utility
The City undertook a study to develop a long-term residuals disposal plan. Six
disposal alternatives were evaluated using three criteria: compliance with residuals
disposal regulations, cost of disposal, and ease of implementation. The six alternatives
considered were as follows:
Simultaneous Compliance Guidance Manual B-35 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
• Discharge to the sanitary sewer is not regulated by the state, however the waste
water treatment plant (WWTP) has a limit of 30 pCi/g for biosolids. Because
liquid residuals samples from the Allen WFP holding pond have an average
gross alpha level of 5,880 pCi/L, the allowable discharge rate would be limited
to a total flow well below the average daily production rate. This option is
therefore not operationally sound;
• Disposal at an approved landfill requires loading and trucking residuals to one
of two landfills at a distances of 44 miles or 100 miles from the plant site. The
landfills are approved for disposal of Resource Conservation and Recovery Act
(RCRA) wastes by the State of Colorado and all material disposed is
manifested and final disposal location within the landfill is documented. The
minimum operating cost of this option is $66,000 per year;
• Compost/topsail amendment recycling requires the City to take responsibility
for loading dry residuals onto City trucks to transport to the facility. The
compost facility can mix residuals immediately upon delivery to avoid
stockpiling of residuals only material. The expected annual operating cost for
this option is $19,900;
• Disposal at a new City mono/ill requires the development, operation, and
eventual closing of a landfill operation used solely for Allen WFP residuals. In
addition, trucking of the residuals to the landfill site would be required. This
option requires a capital investment of approximately $1.4 million and annual
operating costs of $233,000;
• On-site mixing with fill material provides material ready for compost or topsoil
application. A portion of residuals is mixed with fill material with low
background gross alpha levels. City monitoring for gross alpha will be required
to ensure levels below 40 pCi/g. Expected annual operating cost for this option
is $68,100; and
• Disposal at out-of-state approved landfill assumes transport of residuals by
truck or rail cars to the nearest landfill (600 miles away) that accepts TENORM
waste similar to the Allen WFP residuals. Material at this facility is manifested
and final disposal location in the landfill is documented. The expected annual
operational cost is a minimum of $202,500.
In addition to evaluating these six options, the City contracted for a human health
risk assessment to be done to determine possible radiation exposure to City and landfill
employees from managing the residuals, as well as the public exposure arising from
possible future property uses. The risk assessment utilized RESRAD Version 6.21
modeling software to assess the dose to workers and residents from contact with
radioactive material in the treatment plant residuals, either directly or indirectly. Included
were the possible radiation exposures for a landfill worker, a composting facility worker,
and a hypothetical future resident farmer living and farming the area above a closed
landfill. The risk assessment indicated that neither the landfill or compost worker would
be subject to significant radiation exposure resulting from the residuals handling. In
Simultaneous Compliance Guidance Manual B-36 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
addition, the hypothetical future farmer is unlikely to experience exposures above typical
background levels in Colorado. Thus, the risk assessment supported the disposal of
residuals in a local landfill and at the compost recycling facility.
As of March 2006, the sludge is being disposed of at a licensed industrial landfill
within the state.
The City is assessing coagulation schemes that use less alum and produce less
residuals. One such possibility is using a 15 mg/L dose of polyaluminum chloride (PAC1)
with a small supplemental dose of 8 mg/L of alum. Essential to making this change will be
the ability to remove sufficient TOC to meet the Stage 1 D/DBPR.
Since there is currently no state or Federal guidance for disposal of radioactive
water treatment residuals, the City has undertaken an effort with other local utilities to
assist the State CDPHE in development of guidance for the disposal of TENORM in
drinking water residuals.
Results of the Steps Taken
The long-term recommendation to the City is that residuals be transported to the
compost/topsoil amendment recycling center. In addition the City is expected to obtain
approval for both onsite mixing and in-state landfill disposal. Approval for all three
disposal methods has been requested from CDPHE.
The State CDPHE has begun a stakeholder process that will ultimately result in
guidance for utilities in disposing of TENORM.
Implementation and Operational Issues Faced by the Utility
The fact that appropriate Federal and state guidance does not yet exist to provide utilities
with an understanding of requirements has made managing residuals much more complex.
Approval from CDPHE must be obtained as soon as possible as residuals are currently stockpiled
on the plant site at near capacity. If residuals handling operations are impacted with respect to
volume, the drinking water treatment process may also be impacted with respect to production.
Lessons Learned From this Case Study
• The levels of radioactivity in sludge may be significantly higher than expected based
on the background levels in the raw water when the treatment process produces
residuals that concentrate contaminants. These residuals can be liquid and/or solid;
• Disposal to the sanitary sewer is likely to be a problem for almost any concentrated
contaminant that is regulated in biosolids; and
• No regulatory guidance is available to utilities to assist in developing disposal options
for residuals that qualify as TENORM.
Simultaneous Compliance Guidance Manual B-37 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
State regulatory agency groups that have responsibility for radioactive waste products are
generally different from the group responsible for drinking water compliance. This can result in
some complex interactions with regulators as the utility may find themselves in the role of
initiating internal interactions within state agencies. In Colorado, the Hazardous Materials and
Waste Management Division is the licensing group for disposal at hazardous waste disposal
facilities or licensed radioactive waste facilities. Discharge permits, if the liquid waste meets
water quality standards, are issued by the Water Quality Control Division's Colorado Discharge
Permit System. Drinking water is regulated through the Water Quality Control Division
Drinking Water Program.
Simultaneous Compliance Guidance Manual B-38 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
Case Study #7
Granular Activated Carbon Filtration for TOC Removal1
Higginsville Water Treatment Plant
Higginsville, Missouri
Introduction
This case study provides an example of how a utility used GAC to address high
levels of atrazine in its source water and high TTHM levels in its finished water. Most of
the information for this case study came from Leung and Segar (2000). Interested readers
are referred to that reference for more information.
The Higginsville, Missouri Water Treatment Plant is a 2 million gallons per day
(MOD) treatment plant that draws water from a small surface water impoundment in
Missouri. The plant operates 12 hours a day and employs a two stage settling process with
conventional filtration. In 1994, the plant experienced a violation of the atrazine maximum
contaminant level (MCL). The system eventually switched to GAC caps on their filters to
counter the problem.
The source for the Higginsville plant is an impoundment that collects surface
runoff from nearby agricultural areas. It has high hardness and TOC. The average source
water quality is described in Exhibit B.I2.
Exhibit B.12 Average Source Water Quality
Parameter
PH
Alkalinity
Hardness
Turbidity
TOC
Average Value
8.1
89 mg/L as
CaCO3
129 mg/L as CaCO3
18NTU
6 mg/L
The Original Treatment Process at the Higginsville WTP
Exhibit B.I 3 displays a schematic of the treatment scheme at the Higginsville plant.
The plant adds chlorine dioxide to the raw water to control taste and odor problems.
Copper sulfate is also added occasionally to control biological blooms that lead to taste and
odor problems. The water is then pumped to a first set of coagulation and settling basins.
An average of approximately 40 mg/L of alum and 1.7 mg/L of cationic polymer are
added. Lime and fluoride are added to a second flash mix prior to the water passing
through a second set of coagulation and sedimentation basins. The water is then filtered
1 For an example of GAC used as a biological filter after ozonation, see Case Studies 9 and 10.
Simultaneous Compliance Guidance Manual B-39 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
through dual media filters. Chlorine is added both prior to the filters and to a 0.5 million
gallon clearwell after the filters.
When the utility first experienced violations of the atrazine MCL in 1994, it added
powdered activated carbon (PAC) in the first flash mixer to combat the problem. Although
PAC did lower atrazine concentrations below the MCL, it was limited in removal
capabilities because of the short contact time.
Exhibit B.13 Higginsville Water Treatment Plant
Chlorine Dioxide
Alum
(Copper Sulfate
and/or PAC if
needed)
Flash
Mix#l
Chlorine
Simultaneous Compliance Issue Faced by the Utility
The utility was in violation of the atrazine MCL. In addition, high TOC levels
were contributing to total trihalomethane (TTHM) levels which averaged around 80 mg/L,
which could cause problems with Stage 1 and Stage 2 DBPR compliance. Although PAC
provided a temporary solution to the atrazine problem, it was not desirable as a long term
treatment method because of high amounts of sludge. The system also faced periodic taste
and odor episodes.
Steps Taken by the Utility
The utility replaced the anthracite in its dual media filters with GAC in an attempt
to reduce atrazine concentrations and lower TOC and DBFs. The pre-chlorination residual
was also reduced to 0.1 mg/L to prevent degradation of the GAC. Twenty four inches of
GAC were placed on top of the sand and gravel base of the filters. The total EBCT was
7.5 minutes.
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
B-40
March 2007
-------
Appendix B. Case Studies
Results of the Steps Taken
When the GAC caps were first installed, atrazine levels dropped to below detection
and DBF precursors as measured by ultraviolet light adsorption at 254 nm (UV254) dropped
by 50 percent. After about 3 months of operation the removal rates dropped. Removal
rates eventually settled at 30 to 60 percent atrazine removal and 20 percent UV254 removal
after about 6 months of operation. The atrazine concentrations were always below the
MCL of 3 mg/L, averaging between 1 and 2 mg/L. The hydraulic performance of the filter
was unaffected by the change to the GAC cap. Turbidity values leaving the filters were
comparable to values produced previously with the anthracite filters.
Implementation and Operational Issues Faced by the Utility
Adsorption of atrazine and other organics onto the GAC gradually decreased
removal rates over time. A build up of inorganic precipitates, largely calcium, was seen on
the GAC, which also contributed to decreased removal rates. The removal rates can be
restored by regenerating or replacing the GAC, though this can be expensive.
It is possible that initial removal was due to adsorption and biological activity was
later established. If this were the case, subsequent removal resulted from a combination of
adsorption and biological degradation. If biological activity is suspected, care should be
taken not to change the operational characteristics (e.g., fluidized bed heights, backflow
rates) since changes in these operational parameters might impact removal performance.
There was a trade-off between removal of atrazine and removal of UV254. Lower
pH favored UV254 removal at the expense of atrazine removal, while high pH had the
opposite effects.
The system still experiences occasional taste and odor episodes. This is most likely
caused by taste and odor causing compounds passing through the filters because GAC
contact time and design are not optimal for taste and odor control. These episodes have
been dealt with by adding PAC prior to the filters.
Lessons Learned From this Case Study
• GAC caps can be used effectively to reduce pesticide and TOC concentrations;
• Adsorption of organic compounds by GAC is complicated and depends on the
concentrations of other adsorbing compounds present in the source water. Bench
scale tests should be done on the specific source water to determine if GAC itself, as
well as different brands of GAC, will be effective with that water; and
• The pH of the water can impact GAC removal rates for different organic compounds.
Simultaneous Compliance Guidance Manual B-41 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix B. Case Studies
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Simultaneous Compliance Guidance Manual 42 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
Case Study # 8
Nanofiltration Membrane Technology for TOC Removal
PBCWUD Water Treatment Plant #9
West Palm Beach, Florida
The Palm Beach County Water Utilities Department (PBCWUD) utilizes
groundwater supplies that are treated at Water Treatment Plant # 9 (WTP #9) acquired by
the County in 1983. The original plant, constructed in 1971 by private developers, utilized
lime softening, rapid sand filtration, short-term free chlorination for biological growth
control in the filters and chloramination for secondary disinfection. The facility had a
maximum day flow capacity of 13.45 MOD, and was comprised of three treatment trains
with capacities of 1 MOD, 3 MOD, and 10 MOD.
Initially, the plant provided water service to the local area, but it was later
incorporated into the regional water distribution system to provide potable water for the
southern portion of the PBCWUD Service Area. Recognizing the growing demands for
water in the area and the implementation of new drinking water standards, PBCWUD
administered a construction contract for a new 27 MOD nanofiltration plant that was
awarded in 1999. Nanofiltration removes hardness, color, and TOC and its related
chlorinated DBFs which are commonly found in South Florida ground water. The plant
started operational testing in November 2001.
This case study provides an example of several simultaneous compliance issues
that can be associated with nano filtration membrane technology. These issues were
identified during initial start-up operations and have been resolved successfully. The
issues include:
• DBP Rules - ability to remove DBP precursors;
• LCR - ability to provide a non-corrosive water in the PBCWUD distribution
system; and
• Secondary Drinking Water Standards - ability to provide an aesthetically
pleasing water to PBCWUD customers.
Introduction
The mission of PBCWUD is to provide the highest quality drinking water service
in a fiscally and environmentally sound manner. In the last decade, with the enforcement
of the Secondary Drinking Water Standards and the Stage 1 D/DBPR in the State of
Florida, PBCWUD's capital improvement strategy for new water treatment plants has been
focused on nano filtration membrane technology. Membrane water treatment technology is
cost competitive with traditional conventional treatment methods while producing higher
quality potable water; consequently, becoming the dominant water treatment technology in
South Florida.
Simultaneous Compliance Guidance Manual B-43 March 2007
For the Long Term 2 and Stage 2 DBP Rules
-------
Appendix B. Case Studies
In May of 2003, PBCWUD completed Phase I construction of a new, and one of
the largest in the world, nanofiltration membrane treatment plant (WTP #9) with a
maximum capacity of 27 million gallons per day (MOD) finished water, including 23
MOD of membrane permeate and 4 MOD of raw blend water. As stated previously, the
primary reason for the membrane softening is for removal of hardness, color, TOC, and its
related chlorinated DBFs.
The raw water supply for WTP #9 is water from the local surficial Biscayne
Aquifer. The surficial aquifer system provides the water source for most public water
supply wellfields in southeastern Florida. The aquifer system is generally unconfined and
extends from land surface to a depth of approximately 330 feet below land surface (bis).
The ground water is generally colored due to organics, hard and alkaline with varying
amounts of dissolved iron and hydrogen sulfide. Typical ranges of water quality found in
the Biscayne Aquifer are shown in Exhibit B.I4.
Exhibit B.14 Typical ranges of raw water quality in the Biscayne Aquifer
Water Quality Parameter
PH
Alkalinity
Chloride
Total Dissolved Solids
Hardness
Sulfate
Total Organic Carbon
Color
Units
Standard Units
Mg/L as CaCOS
Mg/L
Mg/L
Mg/L as CaCOS
Mg/L
Mg/L
Color Units
Range of Values
7.0-7.5
200-240
<250
250-600
225-275
15-25
10-12
360-400
The New Treatment Process at Water Treatment Plant #9
The treatment train for WTP #9 is shown in Exhibit B. 15. The raw water supplied
to WTP #9 is taken from the shallow surficial aquifer through a series of 24 wells.
Pretreatment includes a sand strainer which removes bulk sand from the raw water stream,
acid injection to control pH to 5.0-5.9, and 5-micron cartridge filters to remove particulates
greater than 5 microns. Six membrane feed pumps located after the micron filters boost
the feed water pressure to 125-132 psi. The nanofiltration membrane building includes
eight membrane treatment trains where each one has two stages with 47 and 22 pressure
vessels, respectively. The degasifier/odor control system functions to remove hydrogen
sulfide and carbon dioxide from the permeate water (product water from the membranes)
and to prevent the emission of odors into the atmosphere. A sodium hypochlorite system
supplies dilute liquid chlorine for disinfection. Six high service pumps supply water to the
distribution system. Post-storage chemical injection points for ammonia, chlorine, and
caustic soda are included in the system to allow final disinfection and/or pH adjustment
before the finished water enters the distribution system. The water entering the
distribution system is monitored for chlorine residual, pH, pressure, and flow. The
impurities removed by the membrane softening trains are consolidated into a concentrate
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
B-44
March 2007
-------
Appendix B. Case Studies
stream and discharged through three-concentrate booster pumps into one deep injection
well.
Treatment Steps Taken by Palm Beach County
• Pretreatment of sand strainer, acid injection, cartridge filtering
• Eight nanofiltration membrane treatment trains
• Degasification and odor control
• Dilute chlorine disinfection
• Post-storage final disinfection and/or pH adjustment and control
• Distribution system monitoring
Simultaneous Compliance Issues Faced by the Utility
Nano filtration membranes remove organic compounds in a molecular weight range of
200 to 20,000 Daltons and reject selected salts (typically divalent). Nanofiltration economically
softens water without the use of salt-regenerated systems and provides unique organic removal
capabilities. While effective in removing organic constituents or DBP precursors, the
nano filtration membrane rejects selected salts, producing treated water with low total dissolved
solids (TDS). Low TDS water has poor buffering capacity and can lead to low pH water, which
is corrosive to metal pipes. Generally, an alkalinity below 25 mg/L as CaCOs (0.5 meq/1) can be
problematic for corrosion of piping (AwwaRF and DVGW-Technologiezentrum Wasser 1996).
This chemically unstable water can result in compliance issues with the Secondary Drinking
Water Standards and the LCR.
Simultaneous Compliance Guidance Manual B-45 March 2007
For the Long Term 2 and Stage 2 DBP Rules
-------
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o
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-------
Appendix B. Case Studies
Steps Taken by the Utility
Steps taken by the utility to overcome the potential simultaneous compliance issues
discussed above occur primarily in the post-treatment process. The post-treatment process
is mainly taking place in the clearwell complex area as shown in Exhibit B. 15. The
clearwell complex consists four major processes: 1) de-gasification process for de-
gasification of hydrogen sulfide and carbon dioxide from the permeate solution, 2) odor
control process to remove hydrogen sulfide from the air, 3) clearwell disinfection process
to create free and combined chlorine, and 4) transfer pump process to discharge the post-
treated water to the storage tanks.
Prior to the de-gasification process, approximately 4 MOD of raw water is
introduced into the treatment train to blend with the 23 MOD of treated water. Blending of
this raw water introduces some of the divalent salts back into the water that had been
previously rejected by the membrane. This provides a more chemically-stable finished
water.
Permeate water from the nanofiltration trains contains excessive amounts of carbon
dioxide and hydrogen sulfide; therefore, 4 identical de-gasifier towers with air blowers in
the clearwell complex function to remove carbon dioxide (CCh) and hydrogen sulfide
(H2S) from the permeate water with the air stripping process. Sodium hypochlorite is
injected into the permeate water before entering into the de-gasifiers for disinfection. The
towers are of the forced draft, randomly packed bed, counter flow type.
The de-gasifiers are designed for maximum influent pH of 6 std. units; influent fkS
with concentration of 1.3 mg/L and removal efficiency of 92 percent; and influent CC>2
with concentration of 77 mg/L and with removal efficiency of 93.5 percent.
The stripped permeate is treated with a chlorine solution and ammonia for
secondary disinfection and caustic soda for pH adjustment.
Results of the Steps Taken
The resulting finished water quality is listed in Exhibit B.I6.
Simultaneous Compliance Guidance Manual B-47 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
Exhibit B.I6 Typical ranges of distribution system water quality
Water Quality Parameter
Total Trihalomethanes
Haloacetic Acids
PH
Alkalinity
Chloride
Total Dissolved Solids
Hardness
Sulfate
Total Organic Carbon
Color
Lead
Copper
Units
ppb
ppb
Standard Units
mg/L as CaCOS
mg/L
mg/L
mg/L as CaCOS
mg/L
mg/L
Color Units
ppb, 90th percentile
ppm, 90th percentile
Range of Values
ND-55.3
ND-51.4
8.5-9.0
30-50
17.2-110
90-300
40-60
6.0-19.5
<0.5
1-7
3
0.134
As shown in Exhibit B.I6, all Secondary Drinking Water Standards, DBF Rule MCLs,
and LCR Action Levels are met.
Implementation and Operational Issues Faced by the Utility
The utility experienced two serious problems in bringing the nanofiltration membrane
treatment plant online. The most serious problem involved numerous leaks in the acid feed
system. As a result of the leaks, the acid system had to be completely rebuilt during the first year
of operation.
The other problem involved the micron cartridge filter housings and the string wound
filter. The filter housings use a single open end cartridge with a stainless steel spring on the
other end to keep tension on the cartridge, holding it in place. In this case, the filters sagged in
the middle causing them to pull out of the socket. With the filter out of place, sand and debris
accumulated on the membranes. This problem was eliminated by modifying the cartridge
housings with a center bracket to support the filters. With these two modifications, the treatment
plant has worked very well and continues to produce very high quality water.
Lessons Learned From This Case Study
• Nanofiltration economically softens water without the use of salt-regenerated systems
and provides unique organic removal capabilities thereby removing disinfection
byproduct precursors;
• Blending a portion of the raw water with treated water and the de-gasification process
significantly enhances the aesthetic qualities of the finished water and results in a
more chemically stable water. This enables PBCWUD to provide their customers
with water that complies with both the LCR and the Secondary Drinking Water
Standards; and
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
B-48
March 2007
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Appendix B. Case Studies
The nanofiltration membranes should be evaluated by monitoring conductivity in the
permeate from the membrane train and from each membrane pressure vessel as
necessary to isolate a problem. Monitoring TOC, particle count or HPC are not
necessary.
References
AWWA. 1999. Reverse Osmosis and Nanofiltration. AWWA Manual M46. Denver:
AWWA.
Glucina, K., A. Alvarez, and J.M. Laine. 2000. Assessment of an integrated membrane
system for surface water treatment. In Proceeding of the conference in drinking and
industrial water production. Italy. 2:113-122.
HDR Engineering, Inc. 2001. Handbook of Public Water Systems. 2nd Edition. New
York: John Wiley & Sons, Inc.
Montgomery Watson Inc. 1998. Palm Beach County Water Utilities Department Water
Treatment Plant No. 3. Membrane Softening Facility Operations Manual Final Report.
pp. 4-19 to 4-20.
Panayides, N. 1999. Operational Procedures of a New 27 MOD Nanofiltration Membrane
Water Treatment Plant (WTP No. 9) in South Florida. Palm Beach County Water
Utilities Department.
Simultaneous Compliance Guidance Manual B-49 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix B. Case Studies
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Simultaneous Compliance Guidance Manual B-50 March 2007
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Appendix B. Case Studies
Case Study #9
Modifying Chloramination Practices to Address Nitrification Issues
Ann Arbor Utilities2
Ann Arbor, Michigan
This case study demonstrates how a utility modified chloramination practices to address
nitrification problems in the distribution system to be in compliance with the Stage 1 DBPR and
the TCR.
Introduction
The City of Ann Arbor operates a two-stage lime softening plant (50 million gallons per
day (MOD) design flow) that treats a blend of surface water and ground water. It serves
approximately 115,000 people. The influent to the plant consists of a blend of Huron River
water (approximately 85 percent) and well water (approximately 15 percent). Typical water
quality parameters for raw river water and well water, prior to any treatment modifications, are
presented in Exhibit B. 17. The water entering the plant has high alkalinity (average alkalinity of
314 mg/L as CaCOs), with high TOC levels (average 6 mg/L).
2 This system is also used in Case Study #10 Ozonation.
Simultaneous Compliance Guidance Manual B-51 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix B. Case Studies
Exhibit B.17 Summary of Relevant Water Quality Parameters at Ann Arbor Before
Treatment Modifications
Water Quality
Parameters
TOC (mg/L)
Minimum
Average
Maximum
PH
Minimum
Average
Maximum
Alkalinity (mg/L as
CaCO3)
Minimum
Average
Maximum
Total Conforms (#/1 00
ml)
Minimum
Average
Maximum
Cryptosporidium (#
oocysts/100 gallons)
Minimum
Average
Maximum
Location1
River
5.5
6.9
8.7
7.9
8.1
8.2
205
215
228
62
781
2,890
ND
114
1,739
Well
1.0
2.2
5.9
301
314
335
0
0
0
Blended Influent
5.1
6.0
8.1
218
234
250
Effluent
2.1
3.0
3.5(3.7)2
9.3(9.1)2
9.4
9.7
28
39
48
ND
ND
ND
Notes:
1. Data collected between July 1994 and June 1995; based on monthly (average) data.
2. Minimum or maximum values (in parentheses) represent minimum or maximum of all measurements, not
limited to monthly average data.
3. ND = Non Detectable
The Treatment Process at the Ann Arbor WTP
The treatment plant is a 50 MOD two-stage lime softening plant that uses chloramines for
primary disinfection. The average operating flow is 20 MOD. Exhibit B.I 8 shows a schematic
of the treatment plant. Raw river water is disinfected with chlorine, then chlorine is added again
with ammonia after filtration to form chloramines. The free chlorine contact time is minimal.
The water is softened with lime (average dose =187 mg/L as CaCOs), at a pH slightly above 1 1 .
From April through November well water is blended with softened water from the first stage
clarifier effluent and recarbonated (i.e., addition of CCh) to bring the pH down to around 10. It
then enters the second-stage clarifier. A cationic polymer is added at this point (average dose
0.62 mg/L) to enhance settling. The water is then recarbonated (i.e., CC>2 is added) down to a pH
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Appendix B. Case Studies
slightly greater than 9, and sodium hexametaphosphate is added to facilitate corrosion control.
The water is then filtered (granular activated carbon (GAC)/sand dual-media filters). After
filtration, sodium hypochlorite and ammonia are added to form chloramines and the finished
water is distributed at an average pH of 9.4.
From December through March the chemical application points are similar to those
during the summer months. However, the well water is blended with the river water prior to the
first stage of the lime softening process to raise the water temperature and improve sludge
de watering.
The chloramines dose ranged from 4.1-6.2 mg/L and Giardia log inactivation by
chloramination ranged from 0.5 to 1.0 logs.
Exhibit B.18 Ann Arbor Water Treatment Plant
Chlorine and
Ammonia Lime
Well Water (During summer)
Polymer
Sodium Hexametaphosphate
NaOCI and Ammonia
Simultaneous Compliance Issue Faced by the Utility
The system switched to chloramines to reduce TTHM formation and to be in compliance
with the Stage 1 Disinfectants/Disinfection Byproducts Rule (D/DBPR). However, the use of
chloramines can result in the presence of ammonia in the distribution system if the proper
chlorine to ammonia (as nitrogen) ratio is not maintained. This increases the potential for
biological nitrification. Nitrification can result in a loss of combined chlorine residual, and result
in sharp increases in HPC bacteria. This increases the chances of a TCR violation.
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Appendix B. Case Studies
Steps Taken by the Utility
To cope with the nitrification problem, Ann Arbor expanded its monitoring program and
made several operational and facility adjustments to improve ammonia feed rate control. The
chlorine to ammonia (as nitrogen) ratio was maintained at 4.75:1, with a target level for free
ammonia entering the distribution system of 0.15 mg/L. Warning and action levels for nitrite in
the system were set at 0.025 and 0.050 mg/L, respectively.
As soon as the utility became aware of its nitrification problem, it attempted to control it
by controlling the concentration of free ammonia reaching the filters. No changes were made to
the existing treatment configuration. However, the system made several operational changes.
Ammonia dosage at the headworks was reduced so that less than 0.15 mg/L of free ammonia
remained in the water when it entered the filters. Along with this, distribution lines were flushed
at low velocity until an average combined chlorine residual of approximately 3 mg/L was
achieved. The Stage 1 DBPR specifies a running annual average maximum residual disinfectant
level (MRDL) for chlorine of 4.0 mg/L (as C12).
During the summer months (i.e., June to September), the system switched back to
chlorination. This was achieved by simply shutting down ammonia addition after filtration and
adjusting the chlorine feed rate. This would ensure that nutrient levels (i.e., ammonia) in the
distribution system were low during the warmer months, when the temperature was most
conducive to the rapid growth of nitrifying organisms. This would decrease biological activity in
the distribution system.
Results of the Steps Taken
As a result of these steps, nitrite concentrations in the distribution system were below
detection level. Also, HPC levels dropped significantly in five of the six locations where
nitrification had previously been found. The system did see an increase in TTHM formation
during the summer months. However, careful monitoring, dosing, and complementary hydrant
flushing (see next paragraph for details) resulted in compliance with the Stage 1 DBPR. The
average and maximum TTHM in the finished water were 24 and 39 //g/L, respectively (based on
the monthly TTHM data collected between July 1994 and June 1995).
Implementation and Operational Issues Faced by the Utility
Although switching to free chlorine during the summer was effective for controlling
nitrification, it appeared to result in higher levels of heterotrophic and coliform bacteria than
when the water was chloraminated. At the same time, increasing the chlorine dose during the
summer months increased TTHM concentrations. As a result, the system decided to continue
disinfecting with chloramines and pursue a more aggressive hydrant flushing program to control
bacterial re-growth in the distribution system.
Analysis revealed that one of the prime causes of nitrification could have been the switch
to a GAC/sand dual-media filter from a pure sand filter. The ammonia added before the water
reached the filters could have provided a nutrient source sufficient for nitrifying bacteria to
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Appendix B. Case Studies
attach, establish, and proliferate within the GAC media. Such a condition could have allowed
the nitrifying organisms to pass through the filter and seed the distribution system if they
survived the chloramine disinfection.
Lessons Learned From this Case Study
• Controlling nitrification in the distribution can be a challenge for utilities switching to
chloramines;
• Carrying a chloramine residual through the treatment plant might increase distribution
system problems with biological nitrification;
• The most common strategies for controlling nitrification are listed below.
- Improving ammonia feed rate control to limit the free ammonia levels entering the
distribution system;
- Implementing a comprehensive distribution system flushing and monitoring
program; and
- Having an alternative disinfection strategy for the warmer months of the year.
• Systems adding ammonia prior to a GAC filter may be more likely to face
nitrification in the distribution system.
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Appendix B. Case Studies
Case Study #10
Ozonation
Ann Arbor Utilities3
Ann Arbor, Michigan
This case study demonstrates how a utility switched to ozonation to meet the Interim
Enhanced Surface Water Treatment Rule (IESWTR) and the Stage 1 and 2 DBPR regulations,
and simultaneously controlled microbial regrowth potential in the distribution system to be in
compliance with the TCR.
Introduction
The City of Ann Arbor serves approximately 115,000 people, and operates a two-stage
lime softening plant (50 MOD design flow) that treats a blend of surface water and ground water.
In 1990, for the reasons outlined below, the Ann Arbor plant decided to switch from chloramines
to ozonation for primary disinfection.
• Ozonation would meet IESWTR CT requirements for viruses at low temperatures;
• In addition to complying with the IESWTR, ozonation was expected to allow the
plant to comply with Stage 1 and 2 DBPRs; and
• Ozonation was also expected to improve taste and odor.
The influent to the plant consists of a blend of Huron River water (approximately 85
percent) and well water (approximately 15 percent). Typical water quality parameters for raw
river water and well water, prior to any treatment modifications, are presented below in Exhibit
B.I9. The water entering the plant has high alkalinity (average influent alkalinity of 314 mg/L as
CaCO3), with high TOC levels (average 6 mg/L).
3 This system is also used in Case Study #9 Modifying Chloramination Practices to Address Nitrification Issues.
Simultaneous Compliance Guidance Manual B-57 March 2007
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Appendix B. Case Studies
Exhibit B.19 Summary of Relevant Water Quality Parameters at Ann Arbor Before
Treatment Modifications
Water Quality
Parameters
TOC (mg/L)
Minimum
Average
Maximum
PH
Minimum
Average
Maximum
Alkalinity (mg/L as
CaCO3)
Minimum
Average
Maximum
Total Conforms
(#/100ml)
Minimum
Average
Maximum
Cryptosporidium
(# oocysts/ 100
gallons)
Minimum
Average
Maximum
TTHM (^g/L)
Minimum
Average
Maximum
HAA54 (Aig/L)
Minimum
Average
Maximum
Location1
River
5.5
6.9
8.7
7.9
8.1
8.2
205
215
228
62
781
2,890
ND
114
1,739
Well
1.0
2.2
5.9
301
314
335
0
0
0
Blended Influent
5.1
6.0
8.1
218
234
250
Effluent
2.1
3.0
3.5 (3.7)2
9.3 (9. 1)2
9.4
9.7
28
39
48
ND
ND
ND
14
24
39
4.2
16
21
Notes:
Data collected between July 1994 and June 1995; based on monthly (average) data.
Minimum or maximum values (in parentheses) represent minimum or maximum of all measurements, not limited
to monthly average data.
ND = Non Detectable
Data collected quarterly between October 1995 and May 1996.
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Appendix B. Case Studies
The Original Treatment Process at the Ann Arbor WTP
The original treatment plant was a 50 MOD two-stage lime softening plant that used
chloramines for primary and secondary disinfection. The average operating flow was 20 MOD.
Exhibit B.20 shows a schematic of the treatment plant, prior to the modifications. Raw river
water was disinfected with chlorine, followed by ammonia addition to form chloramines. The
free chlorine contact time was minimal. The water was softened with lime (average dose =187
mg/L as CaCOs), at a pH slightly above 11. From April through November, well water was
blended with softened water from the first stage clarifier effluent and recarbonated (i.e., addition
of CO2) to bring the pH down to around 10. It then entered the second-stage clarifier. A cationic
polymer was added at this point (average dose 0.62 mg/L) to enhance settling. The water was
then recarbonated down to a pH slightly greater than 9 and sodium hexametaphosphate added, to
facilitate corrosion control. It was then filtered (GAC/sand dual media filters). After filtration,
sodium hypochlorite and ammonia were added to boost the level of chloramines. The finished
water was distributed at an average pH of 9.4.
From December through March the chemical application points were similar to those
during the summer months. However, the well water was blended with the river water prior to
the first stage of the lime softening process to raise the water temperature and improve sludge
de watering.
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Appendix B. Case Studies
Exhibit B.20 Ann Arbor Water Treatment Plant Before Treatment Modifications
Chlorine and
Ammonia Lime
Well Water (During summer)
Polymer
Sodium Hexametaphosphate
NaOCI and Ammonia
Simultaneous Compliance Issue Faced by the Utility
Application of ozone would lower the formation of TTHM and HAA5s and enhance the
ability to meet minimum virus and Giardia inactivation levels (to be in compliance with the
IESWTR). However, ozonation could lead to an increase in the AOC levels in the finished water,
resulting in potential microbial regrowth in the distribution system and non-compliance with the
TCR.
Steps Taken by the Utility
The utility switched to ozonation, followed by biofiltration, in order to address the
simultaneous compliance issue. They no longer pre-chlorinate or pre-chloraminate.
Before switching to ozone, the operators of Ann Arbor's system contacted known ozone
facilities and talked with their engineers and operators to learn what features, in retrospect, they
wish they had installed when they installed the ozone. Based on these discussions, some features
missing from previous plant designs were incorporated into the Ann Arbor system's design. One
example of such as a feature is the addition of waterproof hatches for direct access to the contact
chambers. This eliminated the need for roof entry, which is an important consideration for
system operators.
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Appendix B. Case Studies
Overall process - Exhibit B.21 shows a schematic of the treatment plant after the
modifications. Changes made to the original treatment train are outlined below.
• Ozonation is now the primary disinfection step. The pre-chlorination step was
eliminated;
• The first point of disinfectant addition (i.e., ozonation) is after the secondary clarifier,
and recarbonation. The ozonation pH is 8.0;
• After ozonation, sodium hydroxide is added to raise the pH of the water to 9.4 prior to
adding sodium hexametaphosphate as a corrosion inhibitor; and
• The original dual media (GAC/sand) filters are now operated as biofilters. To help
inactivate HPC bacteria shed from the filters, filter effluent is disinfected with an
average chloramine dose of 3.5 mg/L, and held for approximately 3 hours in the
covered reservoir.
Ozonation Details
There are 8 ozone contact cells with an overall contact time of 16.8 minutes. The system
is operated at a 6 to 10 percent gas concentration. An off-gas recycle system applies ozone to the
first cell, which reduces demand in subsequent cells but does not produce an ozone residual. The
goal is to achieve a residual of 0.1 mg/L or greater in the first cell, and to maintain sufficient
residuals in subsequent cells, to meet the target CT.
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Appendix B. Case Studies
Exhibit B.21 Ann Arbor Water Treatment Plant After Treatment Modifications
Lime
Well Water (During summer)
Polymer
NaOH
Sodium Hexametaphosphate
Biofiltration Operations
The filter consists of 18 inches of GAC and 6 inches of sand. The filtration rate varies
from 0.76 to 3.0 gpm/ft2. The empty bed contact time (EBCT) of the GAC is 3.7 minutes at
design flow and 7.4 minutes at typical flow. Filter backwash frequency is governed by: (a)
effluent turbidity exceeding 0.2 nephelometric turbidity units (NTU), (b) number of hours in
service (usually 80 hours is the cut-off point), and (c) acceptable headloss limits (which is
usually not a controlling criterion). The backwash is performed using finished chloraminated
water.
Results of the Steps Taken
• DBF reductions - Exhibit B.22 shows the TTHM and HAAS concentrations before
and after the modifications at the Ann Arbor plant. Clearly, ozonation resulted in a
significant drop in TTHM and HAAS concentrations, resulting in no compliance
problems with the Stage 1 and Stage 2 DBPRs;
• Bromate formation - Ozonation can oxidize bromide to bromate, which is regulated
by the Stage 1 DBPR at an MCL of 10 //g/L. Influent bromide concentrations at the
ozonation plant ranged from 27 to 80 //g/L, with an average of 67 //g/L. The well
contributes more to the bromide levels than the river water. The average bromide
concentration in the ground water is 100 //g/L, and the Huron River water has an
average bromide concentration of 59 //g/L. The bromate levels in the finished water
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Appendix B. Case Studies
ranged from 2 to 8 //g/L, with an average of 3 //g/L. At its current level of bromate
formation, Ann Arbor meets the bromate MCL; and
• TOC removal - The average influent TOC to the plant after the modifications was 5.5
mg/L (with a range of 4.5-7.0 mg/L). The average effluent TOC was 2.7 mg/L (with
a range of 2.1-3.4 mg/L). Therefore, TOC removal ranged from 40 to 59 percent with
an average of 51 percent, which is quite similar to the TOC removals achieved before
implementing ozonation. The Stage 1 D/DBPR TOC removal requirements for
softening plants with an influent TOC >4.0-8.0 or >8.0 mg/L are 25 and 30 percent,
respectively (USEPA 1998a). The Ann Arbor plant exceeds these requirements.
Higher TOC removal has the advantage of lowering the ozone dose requirements
because the ozone applied is not used up by reactions with TOC.
Exhibit B.22 DBF Formation Before and After Ozonation at Ann Arbor
DBFs
TTHM 0/g/L)
Minimum
Average
Maximum
HAAS faglL)
Minimum
Average
Maximum
Bromate
Minimum
Average
Maximum
Before Modification1
14
24
39
4.2
16
21
After Modifications2
1.4
7.2
13
1.5
5.0
15
2
3or43
8
Notes:
1. Monthly TTHM data collected between July 1994 and June 1995; other DBP data collected quarterly between
October 1995 and May 1996.
2. Data collected in calendar year 1997; based on monthly or quarterly data.
3. Depending on whether the non-detects were set to zero or half the minimum detection level.
Implementation and Operational Issues Faced by the Utility
• Operator training and start-up - It took about 2 to 3 months for the operational staff to
be at ease with the new technology, and about 3 to 5 months for the plant to operate
optimally and smoothly. The change in treatment also changed the operational needs
of the plant; additional mechanics and instrumentation technicians were needed.
Additional resources had to be allocated to treatment operation and maintenance;
• Sludge accumulation over diffusers - This caused fluctuating ozone residuals,
resulting in difficulty obtaining the required CT. The plant has been testing various
chemicals to improve secondary settling to reduce the impact of the sludge on the
ozone system;
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Appendix B. Case Studies
• Liquid Oxygen (LOX) vaporizers did not defrost well in winters, causing the system
to shut down due to low gas flow; and
• Optimizing biofiltration during winters - Extremely large seasonal fluctuations in
temperature have strongly governed treatment strategy at the Ann Arbor plant.
Average monthly river water temperature in 1997 ranged from 7.9 to 22°C, with an
average of 14°C. The lowest temperature in winter during the sampling period was
3°C. Well water temperatures are fairly constant at 14°C. After ozonation and
biofiltration, AOC content ranged from 40 to 210 //g C/L (average = 129 //g C/L).
During the summer, approximately 40 percent of AOC produced by ozonation was
removed during biofiltration, whereas in winter there was practically no removal.
This suggests poor biological activity on the filters in winter months. Ann Arbor
raises the temperature of the influent water in winter by mixing in a larger proportion
of ground water (24-29 percent versus 10-20 percent in the summer). It also
introduces well water at the head of the plant in winter to increase the water
temperature so that treatment processes like biofiltration are more effective.
Lessons Learned From this Case Study
• Ozonation requires a high degree of operational expertise. The key to running a
successful ozonation treatment unit depends greatly on the operator being
comfortable with the new instrumentation and controls;
• Ozonation may not be suitable for influent waters with high bromide concentrations;
and
• Ozonation increases the AOC concentration in finished water. As a result,
biofiltration is required downstream of ozonation to ensure AOC removal and reduce
the opportunity for microbial regrowth in the distribution system. Failure to do so
may result in TCR violations. Biofiltration needs careful monitoring and
optimization, especially during winter when microbial activity is greatly reduced.
One operational strategy is to increase the proportion of ground water in the influent
surface/ground water blend during winter to ensure that treated water has a higher
temperature.
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Appendix B. Case Studies
Case Study #11
Ozonation and Biological Filtration
Sweeney Water Treatment Plant
Wilmington, North Carolina
This case study provides an example of a water system that upgraded its treatment plant
by expanding its capacity from 15 MOD to 25 MOD and installing ozonation and biological
filtration to improve compliance with IESWTR and LT2ESWTR regulations and to increase
aesthetics and customer confidence.
The majority of the information for this case study was found in Najm et al., (2005). For
more information on the Sweeney Water Treatment Plant, please refer to Kennedy et al. (2004).
Introduction
Sweeney Water Treatment Plant (SWTP) is owned and operated by the City of
Wilmington, NC. SWTP uses the Cape Fear River water as its source water, which has high
organic content, high color, and low turbidity. The source water also contains iron and
manganese that can cause aesthetic issues in the finished water. A summary of the source water
quality as received at the SWTP is provided in Exhibit B.23.
Exhibit B.23 Cape Fear River Water Quality
(as received at the SWTP)
Water Quality Parameter (Unit)
TOC (mg/L)
DOC (mg/L)
Filtered UV-254 Abs. (cm"1)
Specific ultraviolet absorbance (SUVA)
(L/(mg-m))
Color (PCU)
Alkalinity (mg/L as CaCO3)
pH
Turbidity (NTU)
Temperature (°C)
Average
5.6
5.4
0.218
4.0
46
25
6.5
16
20
Minimum
4.8
4.6
0.123
2.7
25
16
5.8
3.5
11
Maximum
8.3
7.6
0.337
4.4
76
30
6.8
73
28
Source: Adapted from Najm, et al., 2005
Note: Data collected between Oct. 2001 - July 2002
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Appendix B. Case Studies
The treatment train for the SWTP is shown schematically in Exhibit B.24 below. The
capacity of the SWTP is 25 MOD, and consists of the following two treatment trains:
South Plant (15 MGD)
• Coagulation
• Flocculation
• Sedimentation train
• Intermediate ozonation
• Dual-media GAC/sand filtration
North Plant (10 MGD)
• Coagulation
• High rate clarification (SuperPulsator)
• Intermediate ozonation
• Dual-media GAC/sand filtration
Source water first undergoes pre-ozonation and is then split between the North and South
Plants, where the alkalinity is raised by adding caustic and/or lime. During the rapid mix step of
each treatment train, alum and cationic polymer are added. Primary disinfection requirements of
0.5-log Giardia removal and 2-log virus inactivation are satisfied via the intermediate ozonation
step. After undergoing filtration, the treated waters from the South Plant and North Plant are
joined and caustic and/or lime, chlorine, phosphate, and fluoride are added to the combined filter
effluent (CFE) before the water enters the clearwell. Finally, the effluent of the SWTP's
clearwell receives additional chlorination prior to entering the distribution system.
Exhibit B.24 Schematic of SWTP
Cawtte and/or time
Chiming
Source: Najm, et al., 2005
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Simultaneous Compliance Issue Faced by the Utility
The City of Wilmington upgraded its facility for the following reasons:
• To better accommodate future population growth;
• To comply with LT2ESWTR regulations by providing Cryptosporidium inactivation;
and
• To improve aesthetics and customer confidence.
Application of ozone also lowers the formation of TTHM and HAAS. However,
ozonation could lead to an increase in the AOC levels in the finished water, resulting in potential
microbial regrowth in the distribution system and non-compliance with the TCR. Biofiltration
was used to remove AOC before the water entered the distribution system.
Steps Taken by the Utility
Changes made to the original treatment train of the SWTP are outlined below.
• The North Plant (10 MOD facility) was constructed to be operated simultaneously
with the existing South Plant (15 MOD);
• An ozone generation and dissolution facility was constructed;
• New pretreatment facilities were built for coagulation;
• 12 sand/anthracite filters were converted to biofilters by the use of deep bed dual
media with gravel support and GAC; and
• A SCADA system to monitor/control all processes and equipment in the facility was
installed.
Ozonation and biological filtration began at the SWTP in March, 1998. Details of the
two processes are provided below.
Ozonation Details
SWTP has two application points for ozone. First, in pre-ozonation, ozone is applied
prior to coagulation, at doses between 3-7 mg/L. In intermediate ozonation, ozone is applied
again to settled water at doses between 0.75 - 4.0 mg/L before the water undergoes biological
filtration. The ozonation system at the SWTP uses a maximum of 1380 Ibs ozone/day.
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Appendix B. Case Studies
Biofiltration Details
Specifications for the four new biological filters in the North Plant are as follows:
• Support Gravel - 3"
• Silica Sand-15"
• GAC - 48"
Specifications for the 12 existing filters in the South Plant which were converted to
biological filtration are as follows:
• Support Gravel - 12"
• Silica Sand - 6"
• GAC-21"
Finished water from the SWTP's storage reservoir is used to backwash the biological
filters at both the North and South Plants. At the North Plant, the filters undergo air scouring
prior to backwash, and at the South Plant, the filters use surface sweeps prior to backwash.
Results of the Steps Taken
After the upgrades made at the SWTP, the following water quality improvements have
been observed.
• TOC reduction from raw water to settled water has been observed, and additional
TOC reduction has been observed as result of the biological filtration. Finished water
TOC levels have been reduced to 2.0 - 2.5 mg/L;
• TTHM levels have decreased to 60 |ug/L (typical level);
• HAAS levels have decreased from 48.5 |ug/L (based on 1997 values) to 21.37 |ug/L
(based on 1999 values);
• Iron levels have been reduced from 0.9 mg/L (maximum level in source water) to less
than 0.020 mg/L (finished water); and
• Manganese levels have been reduced from 0.06 - 4.0 mg/L (range of typical to
maximum levels in source water) to less than 0.01 mg/L (finished water).
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Appendix B. Case Studies
Implementation and Operational Issues Faced by the Utility
The SWTP switched from disinfection with chlorine/chlorine dioxide to ozone. Although
no specific issues were described for the SWTP, the following general issues are relevant to
switching to disinfection with ozone.
• Increased costs (due to liquid oxygen, electricity, and higher O&M costs);
• Use of ozone requires a higher level of technical skill from the operators; therefore,
increased training may be required; and
• Since ozonation could lead to an increase in the AOC levels in the finished water,
biofiltration should be implemented to remove the additional AOC.
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Case Study #12
Ultraviolet Disinfection
Poughkeepsie Water Treatment Facility
Poughkeepsie, New York
This case study provides an example of a water system that installed ultraviolet light
(UV) to meet DBF requirements while maintaining compliance with SWTR and IESWTR
requirements. By switching to UV, the system also facilitated compliance with the LT2ESWTR
requirements for Cryptosporidium inactivation.
The information for this case study comes from interviews with water treatment plant
staff (Alstadt 2005, Lill 2005) and from the plant's Web site at http://www.pokwater.com.
Readers are also encouraged to refer to the Ultraviolet Disinfection Guidance Manual for the
Final Long Term 2 Enhanced Surface Water Treatment Rule (USEPA 2006b) for information on
UV sensor calibration procedures and practices.
Introduction
Poughkeepsie's Water Treatment Facility (PWTF) is a surface water treatment plant
located in Poughkeepsie, New York. The plant uses the Hudson River as a source and has a
capacity of 16 MOD. In March 2002 the system began a series of improvements to the plant to
increase its rated capacity, ensure continued compliance with existing regulations, and prepare
for expected future regulations. In the second quarter of 2003 (May 1 through July 31) the
PWTF incurred a violation for exceeding the MCL for HAAS. The system has been in
compliance with the MCLs for both HAAS and TTHM since that date and is completing
modifications, including installing UV, to prevent another exceedance.
PWTF is a conventional surface water treatment plant with rapid mix, followed by three
parallel trains, each with a solids contact tank and sedimentation followed by filtration. The
plant has a total of six filters. An equalization basin succeeds the filters with orthophosphoric
acid added in the first half and sodium hydroxide added in the second half. Chlorine is added in
the sedimentation basins and again just before the water leaves the treatment plant to maintain a
residual in the distribution system.
Simultaneous Compliance Issues Faced by the Utility
The primary issue faced by the system was the need to reduce DBFs. However, in doing
so, the system needed to ensure that it could maintain a high enough CT to ensure compliance
with the requirements for Giardia and viruses. In addition, the LT2ESWTR was expected to
contain new requirements for Cryptosporidium inactivation. The system needed to consider how
any modifications made to address DBFs could impact the system's ability to meet these other
requirements.
Simultaneous Compliance Guidance Manual B-71 March 2007
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Appendix B. Case Studies
Steps Taken by the Utility
In order to reduce DBFs, the system proposed moving the point of disinfection from the
sedimentation basins to just prior to the filters, after more DBF precursors have been removed.
However, in doing so, the system would lose some disinfection contact time. In order to
maintain the necessary CT, the system needed to add an additional contact basin after the filters.
Due to space limitations, constructing a contact basin large enough to maintain CT was not
feasible. Therefore, the system chose to install UV after each filter to provide additional CT and
meet space requirements. In addition, UV does not produce any DBFs, so installing UV rather
than additional chlorine contact time after the filters would further reduce the system's TTHM
and HAAS levels. The UV installation and all associated modifications have been completed.
An additional benefit of installing UV at the PWTF is that UV has been shown to be an
effective technology for inactivating Cryptosporidium at a low dose. The use of UV at PWTF
should enable the system to meet the Cryptosporidium inactivation requirements under the
LT2ESWTR.
PWTF is now planning to switch from chlorine to chloramines for secondary disinfection
to further reduce DBFs in the distribution system. The system will continue to use chlorine and
UV as primary disinfectants, but will begin adding ammonia after the equalization basin to form
chloramines. The system expects to begin using chloramines in 2006 after a new flushing
program has been implemented.
Expected Results of the Steps Taken
Bench-scale pilot testing indicated that installing UV would reduce TTHM and HAAS by
20 percent. Pilot testing also showed that addition of chloramines will reduce DBFs by another
80 percent. The UV installation is expected to provide 3-log inactivation of Giardia and
Cryptosporidium, which will ensure that the system maintains compliance with the Giardia
inactivation requirements under the IESWTR. In addition, the system should be able to meet the
requirements for Cryptosporidium under the LT2ESWTR. Because UV is less effective against
some kinds of viruses, the system expects that it will need to achieve 1 log of virus inactivation
through chlorination after the UV units. The system will meet this requirement with the existing
equalization basin.
Implementation and Operational Issues Faced by the Utility
One of the biggest issues for the PWTF staff during the modifications was learning to
operate and maintain the UV system. PWTF found that operating a UV system is very different
from operating a chemical disinfection system. It is a fairly simple process to determine when a
chemical disinfection system is operating properly because the residual can be easily measured
with a grab sample. Determining how effectively a UV unit is working is much more complex
because there is no measurable residual in the water. In order to determine the UV dose received
by organisms in the water, the operator needs to know the intensity delivered by the UV bulbs
and the transmittance of the water. The UV reactor contains an array of sensors that are used to
determine the intensity and the readings among the sensors can vary significantly, making it
difficult to determine which are correct. PWTF staff had problems with many of the intensity
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Appendix B. Case Studies
sensors in their UV chambers and had to have them replaced. They also had problems with the
transmittance meter. These problems had not been resolved as of Fall 2005.
Obtaining appropriate training was also an issue for the system. Although the
manufacturer provided some training, the water treatment plant staff had not yet worked with the
UV system and were unable to communicate specific training needs to the manufacturer.
Therefore, the plant staff found that many operational and maintenance issues arose during
installation and testing that were not addressed during training.
Programming the UV system and integrating it into plant controls was difficult. The
water treatment plant would have to be shut down if the UV system failed and the control system
would need to be programmed to do so. In addition, the UV units require 10 minutes to cool
down before shutdown to avoid damage to the UV units. Therefore, PWTF had to install a UPS
to hold the power for the UV units for 10 minutes in the event of a power failure. Trying to
consider all possible scenarios and how to react to and program them was a complicated process.
Large UV systems require a significant amount of power, particularly at high doses. The
UV units at PWTF have all been successfully started up and the system is receiving one (1) log
inactivation credit for the UV although the primary disinfectant application point has not yet
been moved. With all UV units running, PWTF observed a 20 percent increase in power
utilization, which significantly increased the plant's power costs. The new UV system also led to
increased maintenance time and costs. The UV system has many components, such as sensors
and bulbs, which require periodic replacement. In addition, the monitoring equipment must be
calibrated regularly.
Lessons Learned From this Case Study
• UV disinfection is very different from chemical disinfection. It is important that
operators undergo training and have continued access to knowledgeable
representatives from the manufacturer during installation and start-up of this
technology to allow them to become comfortable with the new instrumentation and
controls; and
• UV is an effective technology both for reducing DBFs and inactivating Giardia and
Cryptosporidium. However, it also consumes much more electricity than chlorination
or chloramination. Therefore, it is important to consider the availability of electricity
and the financial impact of increased power usage before installing UV.
References
Alstadt, R. 2005. Personal Communication.
Lill, P. 2005. Personal Communication.
Simultaneous Compliance Guidance Manual B-73 March 2007
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Appendix B. Case Studies
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Appendix B. Case Studies
Case Study #13
Chlorine Dioxide for Primary Disinfection and Chloramines for Secondary
Disinfection
Gulf Coast Water Authority
Texas City, TX
This case study provides an example of a water treatment plant with high influent TOC,
high bromide, warm water temperatures, and long residence times in the distribution system that
converted to chlorine dioxide as a primary disinfectant and chloramines as a secondary
disinfectant to reduce the formation of chlorinated DBFs.
The information for this case study was obtained primarily from Krasner et al. (2003).
Readers should refer to that text for more detailed information.
Introduction
The Gulf Coast Water Authority (GCWA), which has been operating since 1981,
operates the Thomas S. Mackey WTP from which treated water is wholesaled to seven
municipalities between Houston and Galveston, TX. All of the systems served by GCWA
conduct their own distribution system monitoring for regulatory compliance. Approximately
92,000 people are served by the GCWA in the seven municipalities. Additionally, raw water is
pumped to industry and treated water is provided to the City of Houston via pipeline between
Houston and Galveston.
The current rated capacity of the Thomas S. Mackey WTP is 25 MGD, with approximate
average and maximum flows of 12 and 20 MGD, respectively.
GCWA uses the Brazos River as their source water, which has moderate to high levels of
TOC, hardness, alkalinity, and bromide.
A summary of the influent water quality to the GCWA is provided in Exhibit B.25.
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Appendix B. Case Studies
Exhibit B.25 Water Quality at GCWA
Water Quality Parameter
Turbidity (NTU)
Hardness (mg/L as CaCO3)
PH
Alkalinity (mg/L as CaCO3)
TOC (mg/L)
Bromide (mg/L)
Influent Concentration
~ 35 (median)
190 (median)
8.25 (median)
135 (median)
4.7 (median)
up to 0.3
The Original Treatment Process at the Gulf Coast Water Authority
Before treatment changes were made at the Thomas S. Mackey WTP, free chlorine was
used as a primary disinfectant. The treatment train consisted of the following:
• Raw water pumping
• Chemical addition (including lime softening)
• Upflow solids contact/clarification
• Recarbonation
• Filtration
• Disinfection (with free chlorine)
• Finished water pumping
The Brazos River has moderate to high concentrations of TOC, as well as high bromide
concentrations. The Thomas S. Mackey WTP was using chlorine as a disinfectant; therefore,
GCWA was facing the challenge of controlling formation of chlorinated and brominated DBFs.
Under these conditions, TTHM formation was ranging up to 350 |ug/L, and TTHM formation
potential (TTHMFP) concentrations were ranging between 800 and 1000 |u,g/L. These concerns
were the main reasons that GCWA changed their disinfection strategy from chlorine to chlorine
dioxide.
Simultaneous Compliance Issues Faced by the Utility
Disinfection with chlorine dioxide raised the following compliance issues for GCWA:
• Ensuring that the system was in compliance with SWTR and IESWTR under all
operating conditions;
• Ensuring that the Stage 1 DBPR TTHM MCL of 80 ug/L and HAAS MCL of 60
|ug/L were not exceeded; and
• Ensuring that the Stage 1 DBPR chlorine dioxide MRDL of 0.8 mg/L and the chlorite
MCL of 1.0 mg/L were not exceeded.
Simultaneous Compliance Guidance Manual B-76 March 2007
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Appendix B. Case Studies
Note, at the time of the treatment train modifications, the plant was initially operating to
comply with a TTHM MCL of 100 |u,g/L and limiting the use of chlorine dioxide to make sure
the sum of chlorine dioxide, chlorite, and chlorate did not exceed 1 mg/L.
Steps Taken by the Utility
GCWA conducted eight phases of research before a final decision was made to use
chlorine dioxide as both a primary and secondary disinfectant. Exhibit B.26 show the various
disinfection strategies implemented at GCWA during the eight phases.
Exhibit B.26 Disinfection Strategies implemented at GCWA
Phase
1
2
3
4
5
6
7
8
Dates
Prior to 11/83
11/83
12/83-4/84
5/84 - 2/85
3/85 - 4/85
5/85-11/85
12/85-SWTR1
SWTR - 2003
Primary Disinfectant
Chlorine
Chloramines
Chloramines
chlorine dioxide
chlorine dioxide
chlorine dioxide
chlorine dioxide
chlorine dioxide2/chlorine
dioxide3
Secondary Disinfectant
chlorine
Chloramines
chlorine4
chlorine
chlorine dioxide
chlorine dioxide/chlorine
chlorine dioxide/
Chloramines
Chloramines
Source: Adapted from Krasner et al., 2003.
Notes:
1 Disinfection scheme changed after SWTR promulgation
2 Chlorine dioxide used intermittently as a pre-oxidant in raw water
3 Chlorine dioxide used as primary disinfectant following filtration
4 Breakpoint chlorination used to achieve free chlorine residual in distribution system
As shown in Exhibit B.26, the eight phases span more than 20 years. Following
promulgation of SWTR, chlorine dioxide was used as a primary disinfectant, which was applied
after filtration. Chloramines were used for secondary disinfection. Additionally, chlorine
dioxide was also intermittently used as pre-oxidant, which was applied to the raw water.
A process schematic of the treatment train at the Thomas S. Mackey WTP after changes
were made is provided in Exhibit B.27.
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B-77
March 2007
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Appendix B. Case Studies
Exhibit B.27 Schematic of Thomas S. Mackey WTP Treatment TrainAfter Changes
Were Made
Caiionic Poiymer •
Low-Lift
a z
H
ated darbon *•
onic Polymer *•
c Sulfate +•
'limps
!i
-^ Chlorine Dioxide (Suspended)
+
Filter Aid Polynw/
Carbon Dioxide
Chlorine (Suspended)
Zinc Polypnosphate
Sodium Fluoride
Chlorine Dioxide
Chlorine
£ To Distribution
Source: Krasner et al., 2003.
Results of the Steps Taken
During the disinfection scheme used in phase 8, TTHM concentrations decreased
significantly from above 300 ng/L when free chlorine was used as the disinfectant. Disinfection
with chlorine dioxide, followed by residual disinfection with chloramines, decreased TTHM
concentrations in the GCWA system by approximately 80 percent, to 50 - 70 |ug/L.
Stage 1 DBPR set a chlorine dioxide MRDL of 0.8 mg/L and a chlorite MCL of 1.0
mg/L. GCWA is in compliance with these requirements. GCWA applies a chlorine dioxide
dose of 0.75 mg/L and, as shown in Exhibit B.28, the chlorite concentration in the treated water
is 0.5 mg/L. However, the chlorine dioxide dose applied is not high enough to obtain any CT log
removal credit under LT2ESWTR.
Simultaneous Compliance Guidance Manual B-78 March 2007
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Appendix B. Case Studies
The GCWA treated water quality after modifications were made to disinfection is
summarized in Exhibit B.28.
Exhibit B.28 Treated Water Quality at GCWA
Water Quality Parameter
Turbidity (NTU)
Hardness (mg/L as CaCO3)
PH
Alkalinity (mg/L as CaCO3)
TOC (mg/L)
Bromide (mg/L)
TTHM (mg/L)
Finished water (clean/veil effluent)
Customers' distribution system
Chlorite (mg/L)
Chlorate (mg/L)
Concentration
0.14 (median)
185 (median)
7.63 (median)
120 (median)
2.9 (median)
0.11 (median)
36-58
50 - 70, (RAA
= 55)
0.5 (median)
0.18 (median)
Note: Based on data collected between January 1996 - November 1997. Partial lime softening was
discontinued in 1994.
Implementation and Operational Issues Faced by the Utility
Because chlorine dioxide was a new technology at the time GCWA was considering
switching disinfectants, they were faced with some technical questions and challenges in the
implementation of chlorine dioxide as their primary disinfectant. Most of the technical issues
concerned distribution system water quality, and therefore there was need for a full-scale plant
study. The main technical issues faced by GCWA are summarized below:
• Effectiveness of disinfection with chlorine dioxide
• Microbial side effects in distribution system
• Production of chlorite as a byproduct of chlorine dioxide generation
• Taste and odor issues related to disinfection with chlorine dioxide
Lessons Learned From this Case Study
• Use of chlorine dioxide can help a system comply with TTHM and HAAS MCLs; and
• Systems may have trouble providing sufficient Cryptosporidium inactivation to
satisfy LT2ESWTR toolbox requirements and still meet the chlorine dioxide MRDL
and chlorite MCL.
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March 2007
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Appendix B. Case Studies
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Appendix B. Case Studies
Case Study #14
Chlorine Dioxide for Primary Disinfection and Chloramines
for Residual Disinfection
Village of Waterloo Water Treatment Plant
Waterloo, New York
This case study provides an example of a small surface water system that successfully
converted from using chlorine as its primary and residual disinfectant to using chlorine dioxide
for primary disinfection and chloramines for residual disinfection. By switching disinfectants,
the Village of Waterloo improved its ability to comply with Stage 1 DBPR and Stage 2 DBPR
requirements, added protection against Cryptosporidium, and improved the system's ability to
maintain a disinfectant residual throughout its distribution system. The narrative for this case
study borrows from Gell and Bromka (2003). Readers should refer to this paper for more
information about the changes made to Waterloo's system.
Introduction
The Village of Waterloo operates a diatomaceous earth (DE) filtration plant that draws
water from Seneca Lake in central New York. The original treatment plant design provides a
nominal capacity of 2 million gallons per day (MOD), but the system plans to expand its service
to neighboring areas. The system currently serves fewer than 10,000 people, but covers a large
geographical area.
The DE filtration produces a low turbidity finished water (usually <0.2 NTU) but does
not significantly reduce concentrations of DBF precursors. When chlorine was used, DBFs
leaving the plant were generally low but increased to levels close to or above the TTHM MCL.
The high DBF levels resulted because the distribution system is sufficiently large and retention
time sufficiently long that chlorine, NOM, and bromide in the water had several days to react
with each other and form high TTHM concentrations.
A summary of Seneca Lake raw water quality is provided in Exhibit B.29.
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Appendix B. Case Studies
Exhibit B.29 Seneca Lake Raw Water Quality
Water Quality Parameter
PH
total alkalinity (mg/L as CaCO3)
total hardness (mg/L as CaCO3)
bromide (mg Br7L)
turbidity (NTU)
TOC (mg C/L)
DOC (mg C/L)
SUVA (L/mg-m)
chlorine demand1 (mg CI2/L)
Average
8.1
84
145
0.32
0.63
2.74
2.51
1.20
1.24
Observed Range
7.7-8.3
69- 119
107- 158
0.28-0.50
0.21 -2.21
2.1 -4.0
1.7-3.2
0.63-3.13
0.35-3.50
Adapted from Gell, R. and Bromka, 2003.
1 Timeframe for the chlorine demand is 1.5 to 2 hours, depending on how much water is being pumped by the
system.
Moderate bromide concentrations in the raw water were causing predominantly
brominated THMs to be formed in the finished water. A 1998 survey of distribution system
samples showed an average TTHM concentration of 79 //g/L and an average HAAS
concentration of 21 //g/L. TTHM concentrations ranged from 48 to 150 //g/L, with
approximately 75 percent of the TTHM being brominated compounds.
At the same time when the Waterloo system was considering treatment modifications to
improve water quality, the system was receiving requests from neighboring areas to expand its
service area. As a result, modifications made at the treatment plant included upgrades to
increase capacity as well as improve water quality.
The Original Treatment Process at the Waterloo WTP
The Village had added potassium permanganate consistently, and PAC/permanganate
seasonally, to control zebra mussel growth and taste and odor problems. These were fairly
effective at controlling seasonal taste and odor problems, but the Village operators were
interested in improving taste and odor treatment for more consistent control.
Chlorine had previously been added after the DE filters and before water entered the
clearwell in order to achieve sufficient Giardia and virus CT. Chlorine was added again at
booster stations in order to maintain a sufficient disinfectant residual throughout
the distribution system.
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March 2007
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Appendix B. Case Studies
Simultaneous Compliance Issues Faced by the Utility
The Village of Waterloo faced problems complying with both the Stage 1 D/DBPR and
the Stage 2 DBPR due to high TTHM concentrations in its distribution system. It was having
trouble maintaining a disinfectant residual throughout the distribution system, which is a
requirement of the SWTR.
At the same time that the Stage 1 DBPR requirements were introduced, the IESWTR and
the LTIESWTR introduced requirements for the removal of Cryptosporidium. Although DE
filtration is not effective at removing DBP precursors, the Village of Waterloo wanted to keep its
DE filters in use because of their simplicity and performance for Cryptosporidium removal. The
Village has been monitoring their raw water for Cryptosporidium for several years, and no
oocysts have been detected.
Steps Taken by the Utility
A pilot study helped the Village realize that installing treatment to remove DBP
precursors would not be efficient, because of the low SUVA concentrations in Seneca Lake's
water. Since the system uses DE for its filtration step, enhanced coagulation would have
required significant modifications to the current filtration process. Moreover, the Waterloo
treatment plant's lakefront location limited options for the disposal of waste streams that would
have been generated by many of the DBP precursor removal options.
Simulated distribution system testing showed that TTHM and HAAS concentrations
could be lowered significantly if the system changed its residual disinfectant from chlorine to
chloramines. This discovery enabled the system to keep its existing DE filtration process by
opting for an alternative disinfection strategy.
In addition, by changing its primary disinfectant from chlorine to chlorine dioxide, the
Village could simplify its operations by eliminating the use of potassium permanganate for zebra
mussel and taste and odor control. Chlorine dioxide is now injected at the intake structure.
Furthermore, changing primary disinfectant from chlorine to chlorine dioxide has enabled a
smaller clearwell expansion, which has reduced the amount of expensive lakefront real estate
needed by the treatment plant.
Chlorine dioxide is added to the intake and maintains a residual throughout the clearwell.
Anhydrous ammonia is added immediately after the clearwell into the discharge pipe before
water is pumped into the distribution system. A few yards downstream of the ammonia addition
point, chlorine gas is injected. Bench scale tests determined the optimum ammonia and chlorine
dosages to maintain a total chlorine residual of 2.0 mg/L over several days.
Before converting from free chlorine to chloramines, the Village, with assistance from its
consultants, conducted a thorough and successful public notification campaign to inform users of
the potential adverse impact of chloramines consumption (primarily for dialysis patients and fish
owners). The Village hosted public meetings, placed newspaper articles, and issued notifications
that provided the important information.
Simultaneous Compliance Guidance Manual B-83 March 2007
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Appendix B. Case Studies
Results of the Steps Taken
The reductions in TTHM and HAAS concentrations after the system switched to chlorine
dioxide and chloramines exceeded the Water Manager's expectations. In 2002, THM levels
were mostly below their detection levels, with one TTHM measurement of 2.1 //g/L in August at
the farthest sampling location. HAAS concentrations in 2002 averaged 8 //g/L. The total
chlorine residual has been maintained throughout the distribution system without the use of re-
chlorination stations.
The chlorine dioxide dosage ranges from 0.4 to 1.00 mg/L, depending on water
temperature. Distribution system chlorite concentrations range from 0.25 to 0.45 mg/L.
The Village has not experienced any uncontrollable re-growth episodes, but uses a
carefully monitored program to address the potential for nitrification and biological re-growth.
As part of this effort, the Village adheres to the following guidelines:
• Maintain a high chlorine to ammonia weight ratio (5:1) at the time when the
chloramines are formed;
• Maintain a finished water total chlorine residual of 2 mg/L and a residual of at least
1.0 mg/L throughout the distribution system;
• Take advantage of the possibility that chlorite, a byproduct of chlorine dioxide
disinfection, may be toxic to nitrifying bacteria;
• Monitor monthly for HPC, nitrite, chlorite, free, and total ammonia at each storage
tank and at key points in the distribution system; and
• Routinely check the percentage of monochloramine in the total chlorine present. Aim
to have at least 95 percent monochloramine leaving the treatment plant.
Since switching disinfectants, the Village has observed two occasions when HPC
numbers increased, and traced the cause of these events to stagnation in a remote storage tank.
Sodium hypochlorite was added to the tank and HPC levels returned to normal. Plans are being
developed to improve mixing in the tanks.
The Water Director believes that previously bothersome taste and odor problems are
being controlled more effectively by using chlorine dioxide. He also believes that the use of
chloramines following chlorine dioxide has prevented the development of nuisance odors
associated with chlorine dioxide in households (see Hoehn et al., 1990).
Implementation and Operational Issues Faced by the Utility
The Village encountered an operational problem when it first converted to chloramines.
Ammonia reacts with calcium and magnesium hardness in the water and produces a scale, even
when hardness values are as low as 35 mg/L as CaCOs. As a result, scaling was clogging the
injector throat of the ammonia feed system. Since a water softening unit was installed to treat
the water that is used for injection, the ammonia feed system has functioned reliably.
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Appendix B. Case Studies
The Village has a service contract with the company that provided the chlorine dioxide
equipment to supply sodium chlorite and monitor and verify the performance of the generator.
This contract has provided the Village with sufficient time to educate its staff on proper
equipment operation.
Further Reading
Readers who are interested in learning more about the Village of Waterloo system should refer to
the following paper:
Gell, R. and J. Bromka. 2003. Successful Application of Chloramines to Manage
Disinfection By-Products. New York State Section AWWA. New York: O'Brien and
Gere.
Simultaneous Compliance Guidance Manual B-85 March 2007
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Appendix C
Guidance for Evaluating Potential Impacts of Treatment Changes on
Distribution Systems
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Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Appendix C
Guidance for Evaluating Potential Impacts of Treatment Changes on
Distribution Systems
This appendix is designed to accompany the guidance manual and provides a starting
point for examining issues that might arise in the distribution system as a result of treatment
changes. Water systems are encouraged to use this document to identify potential issues for their
system and possible solutions to those issues. This guidance manual and its appendices, however,
are not intended to provide comprehensive technical guidance for systems making regulatory
compliance decisions and treatment modifications. Each state may have its own rules and
regulations pertaining to treatment modifications. Systems should contact their state primacy
agency or EPA regional office for more information.
The table below lists treatment changes that could potentially impact the distribution
system and page numbers in this appendix where the potential impacts of particular treatment
changes are discussed. A list of references is also included for each distribution system impact.
Treatment Change
Modifying pH
Change in finished water alkalinity
Change in finished water oxidation/reduction potential
Switching from chlorine to chloramines
Switching coagulant
Modifying chlorine dose with warmer water temperatures
Adding/discontinuing softening
Adding ozone
Adding chlorine dioxide
Enhanced coagulation
Installing nanofiltration
Installing granular activated carbon
Installing ozone without subsequent biological filtration
See Appendix Page
C-2
C-7
C-10
C-ll
C-15
C-17
C-18
C-22
C-25
C-28
C-30
C-33
C-34
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
C-l
March 2007
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Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
MODIFYING pH
The following impacts to your distribution system may result from modifying pH:
• Increased lead and copper in tap water
• Change/disruption of scale
• Colored water
• High iron
• Increased heterotrophic bacteria
• Nitrite/nitrate formation
• Change in DBF concentration/composition
References, along with brief descriptions of treatment impacts, are provided below.
Refer to Section 3.4 for additional information on modifying pH during chlorination.
Increased lead and copper in tap water
Description
As the pH of water decreases, the corrosion potential of the water increases. Therefore, a significant decrease in
finished water pH may result in a significant increase in corrosion of distribution system pipes, resulting in
increased concentrations of metals such as iron, copper, and lead in the water. In addition, if the pH of the water
is too low, protective scales may be disrupted or unable to form on pipe surfaces.
Further Reading
USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance
Manual. EPA 815-R-99-011. August 1999.
USEPA. 2000c. Lead and Copper Rule: Summary of Revisions. Office of Water. EPA 815-R-99-
020.
USEPA. 2003h. Revised Guidance Manual for Selecting Lead and Copper Control Strategies. Office
of Water. EPA 816-R-03-001. March, 2003.
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Simultaneous Compliance Guidance Manual C-2 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Change/disruption of scale
Description
When water is supersaturated with calcium carbonate, the calcium carbonate can precipitate in the distribution
system and form a coating on pipes that protects against corrosion. The pH of the water plays a major role in the
solubility of calcium carbonate. If the pH in the distribution system is too low, calcium carbonate becomes
undersaturated, causing scales to change or become dislodged. Scales can also form in the distribution system
from corrosion byproducts. Because corrosion (and subsequently formation of these scales) is partially dependent
on pH, these scales can also be disrupted by changes in pH.
Further Reading
AWWA. 1999c. Water Quality and Treatment: A Handbook of Community Water Supplies. 5th
Edition. Letterman, R.D. (editor). 1,233 pp. New York: McGraw-Hill.
USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance
Manual. EPA 815-R-99-011. August 1999.
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Colored water
Description
A decrease in pH can lead to increased corrosion and increased solubility of inorganics, which may result in
increased iron and copper levels. A change in pH can also cause disruption of scales. Increased iron levels and
disruption of scale containing iron corrosion byproducts can cause red water. Increased copper levels can cause
blue or green water.
Further Reading
USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance
Manual. EPA 815-R-99-011. August 1999.
White, G.C. 1999. Handbook ofChlorination and Alternative Disinfectants. 4th Edition. New York:
Van Nostrand Reinhold Co.
Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA.
VonHuben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition.278 pp. Denver:
AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Martel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Simultaneous Compliance Guidance Manual C-3 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
High iron
Description
A decrease in pH can lead to increased corrosion and increased solubility of inorganics, which may result in
increased iron levels when iron pipe is used. A change in pH can also cause disruption of scales. If the scales
contain corrosion byproducts, the iron levels in the water can be further increased.
Further Reading
USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance
Manual. EPA 815-R-99-011. August 1999.
White, G.C. 1999. Handbook ofChlorination and Alternative Disinfectants. 4th Edition. New York:
Van Nostrand Reinhold Co.
Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA.
Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Increased heterotrophic bacteria
Description
Films and scales can build up on distribution system pipes and may contain microorganisms as well as inorganic
contaminants and TOC. If the pH fluctuates below 7.0 in the distribution system, these scales may become
dislodged. This would allow the release of the trapped microorganisms into the distribution system, thereby
increasing their numbers in the water.
Further Reading
White, G.C. 1999. Handbook ofChlorination and Alternative Disinfectants. 4th Edition. New York:
Van Nostrand Reinhold Co.
Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA.
VonHuben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver:
AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Gushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Simultaneous Compliance Guidance Manual C-4 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Nitrite/nitrate formation
Description
The optimum pH for nitrification to occur is between 7.5 and 8.5. If systems using chloramines make changes
resulting in a finished water pH in this range, these systems may have problems with nitrification in the
distribution system, causing increased levels of nitrite and nitrate.
Further Reading
Harrington, G.W., D.R. Noguera, C.C. Bone, A.I. Kandou, P.S. Oldenburg, J.M. Regan, and D. Van
Hoven. 2003. Ammonia from Chloramine Decay: Effects on Distribution System Nitrification.
AwwaRF Report 90949. Project #553. Denver: AwwaRF.
Kirmeyer, G.J., M. LeChevallier, H. Barbeau, K. Mattel, G. Thompson, L. Radder, W. Klement, and
A. Flores. 2004a. Optimizing Chloramine Treatment. 2nd Edition. AwwaRF Report 90993. Project
#2760. Denver: AwwaRF.
Kirmeyer, G.J., L.H. Odell, J. Jacangelo, A. Wilczak, andR. Wolfe. 1995. Nitrification Occurrence
and Control in Chloraminated Water Systems. AwwaRF Report 90669. Project #710. Denver:
AwwaRF.
White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York:
Van Nostrand Reinhold Co.
Cowman, G.A., andP.C. Singer. 1994. Effect of Bromide Ion on Haloacetic Acid Speciation
Resulting from Chlorination and Chloramination of Humic Extracts. In Proceedings of A WWA
Annual Conference. New York, NY.
Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA.
USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014.
VonHuben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition.278 pp. Denver:
AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Gushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Simultaneous Compliance Guidance Manual C-5 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Change in DBF concentration/composition
Description
Reducing the pH of the water may allow systems to use a lower chlorine concentration for disinfection, leading to
less DBF formation. Since TTHMs generally show lower formation at lower pH, reducing the pH can also lead to
lower TTHM levels. However, HAA5s generally show higher formation at lower pH, so the HAAS levels may
increase.
Further Reading
White, G.C. 1999. Handbook ofChlorination and Alternative Disinfectants. 4th Edition. New York:
Van Nostrand Reinhold Co.
Connell, G. 1996. The Chlorination/Chloranimation Handbook. 174 pp. Denver: AWWA.
USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014.
VonHuben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition.278 pp.
Denver: AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Martel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Simultaneous Compliance Guidance Manual C-6 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
CHANGE IN FINISHED WATER ALKALINITY
The following impacts to your distribution system may result from changes in finished
water alkalinity:
• Increased lead and copper in tap water
• Change/disruption of scale
• Colored water
• High iron
• Pinhole leaks
The following reference can provide further information about how to address most of
these impacts. Additional references and brief descriptions are listed by impact in the table
below.
AwwaRF and DVGW-Technolpgiezentrum Wasser. 1996. Internal Corrosion of
Water Distribution
Denver: AwwaRF.
Water Distribution Systems. 2nd Edition. AwwaRF Report 90508. Project #725.
Refer to Sections 3.4 and 3.7 for additional information on changes in finished water
alkalinity.
Increased lead and copper in tap water
Description
When alkalinity is removed, the carbonate system must re-equilibrate, resulting in the production of the hydrogen
ion. This in turn results in a lowering of the pH of the water. In addition, as alkalinity decreases, the buffering
capacity of the water decreases, allowing the pH of the water to change more easily during treatment processes.
However, when the alkalinity and pH are high, lead corrosion can also increase as a result of increased lead
solubility and lead complexation with carbonate (AWWA 1999d). Therefore, both increases and decreases in
finished water alkalinity can increase lead levels in tap water. Copper levels can also increase because
bicarbonate is extremely aggressive toward copper (AWWA 1999d).
Further Reading
A\?
Edition. Letterman, R.D. (editor). New York: McGraw-Hill.
• AWWA. 1999c. Water Quality and Treatment: A Handbook of Community Water Supplies. 5th
• AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper Rule
Corrosion Control Treatment. Denver: AWWA.
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Simultaneous Compliance Guidance Manual C-7 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Change/disruption of scale
Description
Alkalinity is a measure of the carbonate and bicarbonate in water. When calcium ions combine with carbonate in
water it can precipitate out to form a protective coating on pipes in the distribution system. If the alkalinity in the
water is subsequently reduced, some of the calcium carbonate may re-dissolve in the water, disrupting the
protective scale on the pipes, which can lead to increased corrosion or release of scales and corrosion by-products.
Lowered alkalinity can also lead to increased leaching from cement/mortar lined pipes. In addition, when
alkalinity is reduces, the pH in the water can fluctuate more easily. Fluctuations in pH can in turn disrupt scales
in the distribution system.
Further Reading
• AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York: McGraw-Hill.
• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance
Manual. EPA 815-R-99-011. August 1999.
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
• Douglas, B.D., and D.T. Merrill. 1991. Control of Water Quality Deterioration Caused by
Corrosion of Cement-Mortar Pipe Linings. Denver: AwwaRF
Colored water
Description
A decrease in alkalinity can result in a lowering of the pH of the water. The buffering capacity of the water also
decreases, allowing the pH of the water to change more easily during treatment processes and in the distribution
system. Decreased pH can lead to increased corrosion of iron pipe. In addition, decreased alkalinity can cause
disruption of protective pipe scales, which can lead to further corrosion. Corrosion byproducts in the water can
cause colored water problems.
Further Reading
AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York: McGraw-Hill.
VonHuben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition.278 pp.
Denver: AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Gushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Simultaneous Compliance Guidance Manual C-8 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
High iron
Description
A decrease in alkalinity can result in a lowering of the pH of the water. The buffering capacity of the water also
decreases, allowing the pH of the water to change more easily during treatment processes. Decreased pH can lead
to increased corrosion of pipes. In addition, decreased alkalinity can cause disruption of protective pipe scales,
which can lead to further corrosion. If iron pipe is present in the distribution system, increased corrosion can
lead to higher iron levels in the water.
Further Reading
• AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York: McGraw-Hill.
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Pinhole leaks
Description
Changes in finished water alkalinity and resulting changes in pH can cause water to become more corrosive to
copper piping, especially in the absence of corrosion inhibitors such as phosphate or NOM.
Further Reading
• Edwards, M, J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole leaks in
residential plumbing. Water Science and Technology. 49(2): 83-90.
• Edwards, M., J.F. Ferguson, S. Reiber. 1994. The Pitting Corrosion of Copper. Journal of American
Water Works Association. 86(7): 74-91.
Simultaneous Compliance Guidance Manual C-9 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
CHANGE IN FINISHED WATER OXIDATION/REDUCTION POTENTIAL
Oxidation/reduction potential (ORP) is the ability of the water to oxidize or reduce
compounds it comes into contact with, and is measured electrochemically. If a treatment change
causes a change in finished water ORP, you could possibly experience increased lead in tap
water or a change or disruption of corrosion scales.
The following references can provide further information about how to address both of
these impacts. Additional references and brief descriptions are listed by impact in the table
below.
• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of
Water Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725.
Denver: AwwaRF.
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control
in Distribution Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Refer to Section 5.1 for additional information on changes to finished water
oxidation/reduction potential.
Increased lead in tap water
Description
Raising or lowering the ORP can affect the redox state of any corrosion products existing in passivating layers in
the distribution system. As the solubility of lead changes with its redox state, this can lead to solublization of lead
and its release into tap water. Ammonia and nitrate can increase leaching of lead from materials such as brass.
Further Reading
AWWA. 2004d. Proceedings of Workshop - Getting the Lead Out: Analysis & Treatment of
Elevated Lead Levels in DC's Drinking Water. San Antonio: WQTC.
Lytle, D.A. and M.R. Schock. 2005. The Formation of Pb(IV) Oxides in Chlorinated Water.
Journal of American Water Works Association. 97(11): 102.
Schock, M.R., K.G. Scheckel, M. DeSantis, and T.L. Gerke. 2005. Mode of Occurrence, Treatment
and Monitoring Significance of Tetravalent Lead. In Proceedings of the A WWA Water Quality
Technology Conference. Denver: AWWA.
Change/disruption of scale
Description
Changing the ORP of the finished water will affect the oxidation/reduction equilibrium between the pipe surface
and the water. Oxidation/reduction reactions may occur at the pipe surface to enable oxidation/reduction
equilibrium to be achieved. If these reactions alter any passivating layers, dissolution and release of metals may
occur.
Further Reading
• AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper Rule
Corrosion Control Treatment. Denver: AWWA.
• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Simultaneous Compliance Guidance Manual C-10 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
SWITCHING FROM CHLORINE TO CHLORAMINES
The following impacts to your distribution system may result from switching from
chlorine to chloramines:
• Increased lead in tap water
• Change/disruption of scale
• Taste and odor
• Increased coliform bacteria
• Increased heterotrophic bacteria
• Nitrite/nitrate formation
• Change in DBF concentration/composition
The following references can provide further information about how to address most of
these impacts. Additional references and brief descriptions are listed by impact in the table
below.
• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition.
278 pp. Denver: AWWA.
• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-
R-99-014.
Refer to Section 5.1 for additional information on switching from chlorine to
chloramines.
Increased lead in tap water
Description
The use of chloramines can lead to nitrification in the distribution system. This in turn can lower the pH of the
water and increase its corrosivity, causing increased levels of metals such as lead, copper, and iron in water in the
distribution system. In addition, because chloramines have a lower oxidation potential than chlorine, switching
from chlorine to chloramines is suspected to cause lead in pipes to change to a form that is more soluble. This can
also increase the lead concentration in the water in the distribution system.
Further Reading
• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF
Simultaneous Compliance Guidance Manual C-l 1 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Change/disruption of scale
Description
The use of chloramines can lead to nitrification in the distribution system. Nitrification can lower the pH of the
water, causing disruption to scales formed from corrosion byproducts or protective scales, such as calcium
carbonate.
Further Reading
USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance
Manual. EPA 815-R-99-011. August 1999.
AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York: McGraw-Hill.
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Taste and odor
Description
Monochloramine is a preferred chlorine residual with regard to odor quality and customer perceptions.
Dichloramine can add a more pungent, sharper chlorine-type odor to the water at lower levels such that some
utilities have set a goal to keep the percentage dichloramine of the total combined chlorine residual below 20%
(ref. Lines 11-12 page 7-6). Monochloramine is preferred over free chlorine as it takes a higher level to reach odor
detection by customers, and changes in odor following changes in the residual are much less noticeable by
customers. However, there have been reports of off-odors associated with nitrification, which could come from
biological growth, loss of chloramine residual, and related conditions.
Further Reading
Singer, P.C. (editor). 1999. Formation and Control of Disinfection By-Products in Drinking Water.
424 pp. Denver: AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Martel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Simultaneous Compliance Guidance Manual C-12 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Increased coliform bacteria
Description
The use of chloramines can lead to nitrification in the distribution system. The nitrite formed through nitrification
exerts a high chlorine demand, which will rapidly deplete the disinfectant residual (Cowman and Singer 1994).
When the disinfectant residual is low or depleted, microorganisms such as coliforms and heterotrophic bacteria
can proliferate.
Further Reading
White, G.C. 1999. Handbook ofChlorination and Alternative Disinfectants. 4th Edition. New York:
Van Nostrand Reinhold Co.
Kirmeyer, G.J., L.H. Odell, J. Jacangelo, A. Wilczak, andR. Wolfe. 1995. Nitrification Occurrence
and Control in Chloraminated Water Systems. AwwaRF Report 90669. Project #710. Denver:
AwwaRF.
Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Increased heterotrophic bacteria
Description
The use of chloramines can lead to nitrification in the distribution system. The nitrite formed through nitrification
exerts a high chlorine demand, which will rapidly deplete the disinfectant residual (Cowman and Singer 1994).
When the disinfectant residual is low or depleted, microorganisms such as coliforms and heterotrophic bacteria
can proliferate.
Further Reading
White, G.C. 1999. Handbook ofChlorination and Alternative Disinfectants. 4th Edition. New York:
Van Nostrand Reinhold Co.
Cowman, G.A. and P.C. Singer. 1994. Effect of Bromide Ion on Haloacetic Acid Speciation
Resulting from Chlorination and Chloramination of Humic Extracts. In Proceedings of A WWA
Annual Conference. New York, NY.
Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Simultaneous Compliance Guidance Manual C-13 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Nitrite/nitrate formation
Description
Nitrification can occur when chloramines are used to maintain a residual in the distribution system due to the
presence of ammonia, which is used to form chloramines. Nitrifying bacteria convert the excess ammonia into
nitrite and nitrate. Nitrification is not a problem when chlorine is used to maintain a residual, because no
ammonia is used.
Further Reading
Kirmeyer, G.J., L.H. Odell, J. Jacangelo, A. Wilczak, andR. Wolfe. 1995. Nitrification Occurrence
and Control in Chloraminated Water Systems. AwwaRF Report 90669. Project #710. Denver:
AwwaRF.
Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Gushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Kirmeyer, G.J., M. LeChevallier, H. Barbeau, K. Mattel, G. Thompson, L. Radder, W. Klement, and
A. Flores. 2004a. Optimizing Chloramine Treatment. 2nd Edition. AwwaRF Report 90993. Project
#2760. Denver: AwwaRF.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Cowman, G.A. and P.C. Singer. 1994. Effect of Bromide Ion on Haloacetic Acid Speciation
Resulting from Chlorination and Chloramination of Humic Extracts. In Proceedings, A WWA Annual
Conference. New York, NY.
Harrington, G.W., D.R. Noguera, C.C. Bone, A.I. Kandou, P.S. Oldenburg, J.M. Regan, and D. Van
Hoven. 2003. Ammonia from Chloramine Decay: Effects on Distribution System Nitrification.
AwwaRF Report 90949. Project #553. Denver: AwwaRF.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York:
Van Nostrand Reinhold Co.
Change in DBF concentration/composition
Description
Chloramines react more slowly with organic matter than free chlorine does. Therefore, switching from chlorine
to chloramines can significantly reduce DBF formation. However, it will not completely eliminate DBF
formation - TTHM and HAA5 will still be formed, though this formation may be undetectable, largely as a result
of excess free chlorine or the hydrolysis of monochloramine to from free chlorine.
Further Reading
USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance
Manual. EPA 815-R-99-011. August 1999.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Valentine, R. 2001. Mechanisms and Kinetics of Chloramine Loss and By-Product Formation in
the Presence of Reactive Drinking Water Distribution System Constituents. Washington, D.C.:
USEPA.
Simultaneous Compliance Guidance Manual C-14 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
SWITCHING COAGULANT
The following impacts to your distribution system may result from switching your
coagulant:
• Change in finished water pH
• Increased lead and copper in tap water
• Change/disruption of scale
• Change in finished water NOM
• Change in chloride:sulfate ratio
The following references can provide further information about how to address most of
these impacts. Additional references and brief descriptions are listed by impact in the table
below.
• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous
Compliance Guidance Manual. EPA 815-R-99-011. August 1999.
• USEPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening
Guidance Manual. Office of Water. EPA 815-R-99-012.
Refer to Sections 3.3 and 3.7 for additional information on switching coagulants.
Change in finished water pH
Description
Different coagulants have different optimum pH ranges. Therefore, when switching coagulants, it may be
necessary to adjust the pH to achieve maximum contaminant removal. In addition, some coagulants consume
alkalinity, which results in decreased buffering capacity and allows the pH to change more easily.
Further Reading
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Gushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Increased lead and copper in tap water
Description
The optimal pH range for coagulants varies by coagulant. Therefore, switching coagulants can require a pH
change, and if the pH is significantly reduced, can lead to increased lead and copper corrosion in the distribution
system.
Further Reading
USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014.
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Simultaneous Compliance Guidance Manual C-15 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Change/disruption of scale
Description
The optimal pH range for coagulants varies by coagulant. Therefore, switching coagulants can require a change
in the operating pH, and consequently, in the distribution system. A higher pH can decrease the rate of corrosion,
thereby decreasing the formation of scales from corrosion byproducts. A higher pH can also allow the formation
of a protective calcium carbonate scale. A lower pH can cause disruption or dislodgement of scales formed from
corrosion byproducts or protective scales, such as calcium carbonate.
Further Reading
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Change in finished water NOM
Description
To accomplish enhanced coagulation, systems may switch coagulants to improve removal of TOC, which is a
surrogate measure of NOM. Therefore, the NOM entering the distribution system is significantly reduced. Some
NOM in the finished water can help inhibit corrosion.
Further Reading
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Gushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Change in chloride: sulfate ratio
Description
Some coagulants, such as aluminum sulfate (alum) and ferric sulfate add sulfate to the water. Other coagulants,
such as ferric chloride add chloride to the water. Therefore, switching to or from any of these coagulants can
affect the chloride to sulfate ratio. A shift in the sulfate to chloride ratio can cause increased lead and copper
corrosion and can alter iron corrosion in the distribution system.
Further Reading
• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Simultaneous Compliance Guidance Manual C-16 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
MODIFYING CHLORINE DOSE WITH WARMER WATER TEMPERATURES
The following impacts to your distribution system may result from reducing chlorine
dose during warmer water temperatures in order to reduce DBF formation:
• Increased coliform and heterotrophic bacteria
• Increased loss of chlorine residual in the distribution system
The following references can provide further information about how to address this
distribution system impact:
• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th
Edition. New York: Van Nostrand Reinhold Co.
• Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver:
AWWA.
• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition.
278 pp. Denver: AWWA.
• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water
Transmission and Distribution. 3rd Edition. 553 pp. Denver: AWWA.
• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D.
Smith, M. LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesen, and R.
Gushing. 2000b. Guidance Manual for Maintaining Distribution System Water
Quality. AwwaRF Report 90798. Project #357. Denver: AwwaRF and AWWA.
• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp.
Denver: AWWA.
• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-
R-99-014.
Increased coliform and heterotrophic bacteria
Description
Chlorine is a more effective disinfectant at higher temperatures. However, because it reacts more quickly at
warmer temperatures, the chlorine residual may dissipate more quickly in the distribution system, leaving low or
no residual near the end of the distribution system. This can allow increased microbial growth in these areas. In
addition, the growth rate of microorganisms is more rapid at higher temperatures, making them more difficult to
control. These factors can lead to increased coliform and heterotrophic bacteria if the chlorine dose is lowered
during warmer water temperatures.
Increased loss of chlorine residual
Description
Lowering the chlorine dose will mean that there is less residual in the distribution system. Higher temperatures
will also cause reactions of the residual with chlorine demand to proceed faster.
Simultaneous Compliance Guidance Manual C-17 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
ADDING/DISCONTINUING SOFTENING
The following impacts to your distribution system may result from adding or
discontinuing softening:
• Change in finished water pH
• Increased lead and copper in tap water
• Change/disruption of scale
• Taste and color problems
• Change in finished water NOM
• High iron
• Change in DBF concentration/composition
• Pinhole leaks
The following reference can provide further information about how to address all of these
impacts. Additional references and brief descriptions are listed by impact in the table below.
• USEPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening
Guidance Manual. Office of Water. EPA 815-R-99-012.
Refer to Section 3.8 for additional information on adding or discontinuing softening.
Change in finished water pH
Description
In enhanced softening, the pH of the water is typically raised to a value above 10. However, most other water
treatment processes are operated at much lower pHs. Therefore, when switching to enhanced softening, systems
can expect to have a much higher finished water pH. Conversely, if a system switches from enhanced softening
to another technology, the operating and finished water pH will be much lower.
Further Reading
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Increased lead and copper in tap water
Description
In enhanced softening, the pH of the water is typically raised to a value above 10. However, most other water
treatment processes are operated at much lower pHs. Therefore, when discontinuing softening, systems can
expect to have a much lower finished water pH. As the pH decreases, systems can expect an increase in corrosion
of distribution system pipes, resulting in increased concentrations of metals such as iron, copper, and lead in the
water.
Simultaneous Compliance Guidance Manual C-18 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Further Reading
• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Change/disruption of scale
Description
Installing softening requires an increase in operating pH, while discontinuing softening requires a reduction in pH.
A higher pH can decrease the rate of corrosion, thereby decreasing the formation of scales from corrosion
byproducts. A higher pH can also allow the formation of a protective calcium carbonate scale. A lower pH can
cause disruption or dislodgement of scales formed from corrosion byproducts or protective scales, such as
calcium carbonate.
Further Reading
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Taste and color problems
Description
Aluminum can be found in source water or introduced through coagulant use or as an impurity in lime.
Aluminum is more soluble at high pH. Since enhanced softening is conducted at high pH, it allows more
aluminum to pass through the treatment plant. In waters with high magnesium, enhanced softening can form
lighter floe, which may not settle as well. This can also allow higher levels of aluminum to enter the distribution
system. When aluminum precipitates out in the distribution system it can cause colored water and taste
complaints.
Further Reading
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
VonHuben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver:
AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Martel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Simultaneous Compliance Guidance Manual C-19 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Change in finished water NOM
Description
Enhanced softening preferentially removes high molecular weight organic molecules and organic molecules with
oxygen-containing functional groups. NOM removal through enhanced softening varies widely depending on the
nature and concentration of the NOM, water quality characteristics such as hardness, other plant treatment
processes, and type and dose of the softening chemical. Some NOM in the finished water can help inhibit
corrosion.
Further Reading
AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York : McGraw-Hill.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Martel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
High iron
Description
In enhanced softening, the pH of the water is typically raised to a value above 10. However, most other water
treatment processes are operated at much lower pHs. Therefore, when discontinuing softening, systems can
expect to have a much lower finished water pH. As the pH decreases, systems can expect an increase in corrosion
of distribution system pipes, resulting in increased concentrations of metals such as iron, copper, and lead in the
water.
Further Reading
• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Change in DBF concentration/composition
Description
Softening removes DBF precursors, reducing the formation of DBFs. Therefore, by installing softening, systems
can decrease TTHM and HAA5 levels in the plant and the distribution system. Systems installing softening will
also see a shift in the balance of DBFs in the distribution system because TTHM formation is favored over HAA5
formation at the high pH levels used in softening. In addition, prechlorination with softening can reduce the
amount of DBF precursor removal (AWWA 1990) and should be avoided if possible.
Further Reading
AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York: McGraw-Hill.
VonHuben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver:
AWWA.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Simultaneous Compliance Guidance Manual C-20 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Pinhole leaks
Description
Adding softening raises pH and alkalinity of the finished water. Discontinuing softening lowers the pH and
alkalinity. Lower pH can be corrosive to copper, but high pH in the absence of inhibitors such as NOM has also
been shown to initiate pitting corrosion in copper.
Further Reading
Edwards, M, J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole leaks in
residential plumbing. Water Science and Technology. 49(2): 83-90.
Edwards, M., J.F. Ferguson, S. Reiber. 1994. The Pitting Corrosion of Copper. Journal of American
Water Works Association. 86(7): 74-91.
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
Simultaneous Compliance Guidance Manual C-21 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
ADDING OZONE
The following impacts to your distribution system may result from adding ozone:
• Increased lead and copper in tap water
• Taste and odor
• Change in finished water NOM
• Colored water
• High iron
• Change in DBF concentration/composition
The following references can provide further information about how to address most of
these impacts. Additional references and brief descriptions are listed by impact in the table
below.
• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-
R-99-014.
• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous
Compliance Guidance Manual. EPA 815-R-99-011. August 1999.
Refer to Section 5.2 for additional information on adding ozone.
Increased lead and copper in tap water
Description
When ozone reacts in water it produces dissolved oxygen. Dissolved oxygen can cause increased growth of
aerobic bacteria, which can lead to microbial-induced corrosion in the distribution system. Dissolved oxygen is
also corrosive, and if not removed, it can directly cause lead and copper corrosion in the distribution system.
Ozonation also breaks down organics into smaller molecules that are more readily used as a food source by
microorganisms. If not removed, this can lead to increased microbial growth and microbial-induced corrosion in
the distribution system.
Further Reading
• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York:
Van Nostrand Reinhold Co.
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Simultaneous Compliance Guidance Manual C-22 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Taste and odor
Description
Ozonation reacts with organics to break them down into smaller molecules, such as aldehydes and ketones.
Aldehydes can impart tastes and odors to water. In addition, ozone itself can impart an "ozonous" or "oxidant"
taste to the water even in the absence of a residual (AwwaRF and Lyonnaise des Eaux 1995).
Further Reading
AwwaRF and Lyonnaise des Eaux. 1995. Advances in Taste and Odor Treatment and Control.
AwwaRF Report 90610. Project #629. Denver: AwwaRF.
Singer, P.C. (editor). 1999. Formation and Control of Disinfection By-Products in Drinking Water.
424 pp. Denver: AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
VonHuben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver:
AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Martel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Change in finished water NOM
Description
Ozone reacts with NOM in water to destroys many DBF precursors. However, ozone breaks the NOM down into
smaller organic molecules that are readily used as a food source by microorganisms, referred to as AOC. If ozone
is followed by biological filtration, the AOC concentration can also be significantly reduced.
Further Reading
Singer, P.C. (editor). 1999. Formation and Control of Disinfection By-Products in Drinking Water.
424 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Martel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Colored water
Description
Ozonation produces dissolved oxygen in water, which is corrosive. In addition, dissolved oxygen can cause
increased microbial activity in the distribution system and microbial-induced corrosion. If iron pipe is present in
the distribution system, increased corrosion can lead to colored water problems.
Simultaneous Compliance Guidance Manual C-23 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Further Reading
White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York:
Van Nostrand Reinhold Co.
VonHuben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver:
AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
High iron
Description
Ozonation produces dissolved oxygen in water, which is corrosive. In addition, dissolved oxygen can cause
increased microbial activity in the distribution system and microbial-induced corrosion. If iron pipe is present in
the distribution system, increased corrosion can lead to higher iron levels in the water.
Further Reading
USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014.
USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance
Manual. EPA 815-R-99-011. August 1999.
White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York:
Van Nostrand Reinhold Co.
Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Change in DBF concentration/composition
Description
Ozone does not form chlorinated DBFs. Therefore, switching from chlorine or chlorine dioxide as a primary
disinfectant to ozone will result in significantly lower levels of TTHM and HAAS. However, ozone reacts with
bromide to form bromate, which is a regulated DBF.
Further Reading
• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver:
AWWA.
• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Simultaneous Compliance Guidance Manual C-24 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
ADDING CHLORINE DIOXIDE
The following impacts to your distribution system may result from adding chlorine
dioxide:
• Increased lead and copper in tap water
• Taste and odor
• Change in finished water NOM
• Colored water
• High iron
• Change in DBF concentration/composition
References, along with brief descriptions, that are specific to individual issues are listed
by impact in the table below. Refer to Sections 5.4 and 5.5 for additional information on adding
chlorine dioxide.
Increased lead and copper in tap water
Description
Changing to chlorine dioxide from another oxidant can change the ORP of the tap water. Changes in ORP can
alter the nature of passivating layers and could result in the release of lead and other metals into the distribution
system. It is also possible that AOC formed by chlorine dioxide could encourage microbial-induced corrosion.
Further Reading
• AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper Rule
Corrosion Control Treatment. Denver: AwwaRF.
• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF
Taste and odor
Description
Chlorine dioxide has a strong chlorinous odor. Even when chlorine dioxide is used only as a primary disinfectant,
customers may still detect a strong chlorinous odor at the tap as chlorite can combine with free chlorine in the
distribution system to form chlorine dioxide. If a customer has recently installed new carpeting, airborne organic
compounds from the carpeting can react with the chlorine dioxide emanating from the customer's tap to form
offensive odors. These odors have been described as "cat-urine-like" and "kerosene-like" (Hoehn et al. 1990).
Simultaneous Compliance Guidance Manual C-25 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Further Reading
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA
VonHuben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver:
AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Change in finished water NOM
Description
Chlorine dioxide reacts with organic matter in water. These reactions can form smaller organic molecules or
AOC. Although AOC production is not as much of an issue with chlorine dioxide as it is with ozone, it is still
possible AOC could increase and in turn increase microbial growth.
Further Reading
USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014.
Andrews, R.C., Z. Alam, R. Hofmann, L. Lachuta, R. Cantwell, S. Andrews, E. Moffet, G.A. Ganon,
J. Rand, and C. Chauret. 2005. Impact of Chlorine Dioxide on Transmission, Treatment, and
Distribution System Performance. AwwaRF Report 91082. Project #2843. Denver: AwwaRF.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Colored water
Description
Chlorine dioxide can react with organic chemicals to form AOC. AOC can act as a food source for microbes,
which can in turn increase the corrosion rate causing corrosion products to be released into the distribution system.
The change in ORP can also destabilize some already formed layers of corrosion products, leading to colored
water.
Simultaneous Compliance Guidance Manual C-26 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Further Reading
USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014.
Andrews, R.C., Z. Alam, R. Hofmann, L. Lachuta, R. Cantwell, S. Andrews, E. Moffet, G.A. Ganon,
J. Rand, and C. Chauret. 2005. Impact of Chlorine Dioxide on Transmission, Treatment, and
Distribution System Performance. AwwaRF Report 91082. Project #2843. Denver: AwwaRF.
VonHuben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver:
AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Gushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
High iron
Description
Chlorine dioxide can react with organic matter to form AOC which can cause microbial-induced corrosion.
Changes in water ORP resulting from chlorine dioxide use may also allow dissolution of existing scales.
Further Reading
USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014.
Andrews, R.C., Z. Alam, R. Hofmann, L. Lachuta, R. Cantwell, S. Andrews, E. Moffet, G.A. Ganon,
J. Rand, and C. Chauret. 2005. Impact of Chlorine Dioxide on Transmission, Treatment, and
Distribution System Performance. AwwaRF Report 91082. Project #2843. Denver: AwwaRF.
Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Change in DBF concentration/composition
Description
Chlorine dioxide does not form significant amounts of TTHM or HAA5. Therefore, switching from chlorine or
chloramines to chlorine dioxide will result in lower levels of these DBFs. However, chlorine dioxide generators
produce some chlorine as a byproduct so some TTHM and HAA5 will be formed. In addition, chlorine dioxide
can oxidize bromide ions to bromine, which can then react with organic matter in the water to produce brominated
DBFs. Chlorine dioxide also reacts with NOM to produce chlorite, which is a regulated DBF.
Further Reading
USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014.
White, G.C. 1999. Handbook ofChlorination and Alternative Disinfectants. 4th Edition. New York:
Van Nostrand Reinhold Co.
Gates, D. 1997. The Chlorine Dioxide Handbook. 177pp. Denver: AWWA.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
VonHuben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver:
AWWA.
Simultaneous Compliance Guidance Manual C-27 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
ENHANCED COAGULATION
The following impacts to your distribution system may result from using enhanced
coagulation:
• Reduction in finished water pH
• Increased lead and copper in tap water
• Change/disruption of scale
• Change in finished water NOM
• Change in DBF concentration/composition
• Change in chloride:sulfate ratio
The following references can provide further information about how to address most of
these impacts. Additional references and brief descriptions are listed by impact in the table
below.
• USEPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening
Guidance Manual. Office of Water. EPA 815-R-99-012.
• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous
Compliance Guidance Manual. EPA 815-R-99-011. August 1999.
Refer to Section 3.7 for additional information on using enhanced coagulation.
Change in finished water pH
Description
Enhanced coagulation tends to reduce the pH of the water. This can be accomplished by adding chemicals
specifically to reduce the pH to as low as 5.5 or as a consequence of using heavy alum or ferric coagulant doses.
Further Reading
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Gushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900pp. Denver: AWWA.
Increased lead and copper in tap water
Description
Enhanced coagulation tends to reduce the pH of the water. This can be accomplished by adding chemicals
specifically to reduce the pH to as low as 5.5 or as a consequence of using heavy alum or ferric coagulant doses.
In addition, switching coagulants for enhanced coagulation can lead to reduced pH. A reduction in pH can cause
increased lead and copper corrosion.
Further Reading
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Simultaneous Compliance Guidance Manual C-28 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Change/disruption of scale
Description
Enhanced coagulation tends to reduce the pH of the water. This can be accomplished by adding chemicals
specifically to reduce the pH to as low as 5.5 or as a consequence of using heavy alum or ferric coagulant doses.
A lower pH can cause disruption or dislodgement of scales formed from corrosion byproducts or protective
scales, such as calcium carbonate.
Further Reading
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Change in finished water NOM
Description
Enhanced coagulation increases the removal of TOC, which is a surrogate measure of NOM. Therefore, the
NOM entering the distribution system is significantly reduced. Some NOM in finished water can help inhibit
corrosion.
Further Reading
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Change in DBF concentration/composition
Description
Enhanced coagulation improves the removal of DBF precursors in a conventional water treatment plant, reducing
the formation of DBFs. Therefore, by practicing enhanced coagulation, systems can decrease TTHM and HAAS
levels in the plant and the distribution system.
Further Reading
• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver:
AWWA.
• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Change in chloride: sulfate ratio
Description
One option for systems initiating enhanced coagulation is to switch coagulants to increase TOC removal. Some
coagulants, such as aluminum sulfate (alum) and ferric sulfate add sulfate to the water. Other coagulants, such as
ferric chloride add chloride to the water. Therefore, switching to or from any of these coagulants can affect the
chloride to sulfate ratio and, as a result, may cause increased lead and copper corrosion.
Further Reading
• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Simultaneous Compliance Guidance Manual C-29 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
INSTALLING NANOFILTRATION
The following impacts to your distribution system may result from installing
nanofiltration:
• Change in finished water pH
• Increased lead and copper in tap water
• Change/disruption of scale
• Change in finished water NOM
• Colored water
• High iron
• Change in DBF concentration/composition
• Pinhole leaks
The following reference can provide further information about how to address most of
these impacts. Additional references and brief descriptions are listed by impact in the table
below.
• AWWA. 1999. Reverse Osmosis and Nanofiltration. AWWA Manual M46.
Refer to Section 4.3 for additional information on installing nanofiltration.
Change in finished water pH
Description
Nanofiltration can remove virtually all paniculate matter as well as larger dissolved compounds. However, it
cannot remove dissolved gasses. Therefore, carbon dioxide in the feed water is not removed, while alkalinity,
hardness, and other dissolved compounds are removed. Therefore, the carbonate system must re-equilibrate,
resulting in the production of the hydrogen ion and loss of alkalinity. This in turn results in a lowering of the pH
of the water.
Further Reading
Schippers, J.C., J.C. Kruithof, M.M. Nederlof, J.A.M.H. Hofrnan, and J. Taylor. 2004. Integrated
Membrane Systems. AwwaRF Report 90899. Project #264. Denver: AwwaRF.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Gushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA.
Increased lead and copper in tap water
Description
Nanofiltration can also result in a lowering of the pH of the water. The lower pH water will be more corrosive to
lead and copper piping in the distribution system. As a result, both increased lead and copper levels can occur.
Simultaneous Compliance Guidance Manual C-30 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Further Reading
• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Change/disruption of scale
Description
Nanofiltration can also result in a lowering of the pH of the water. A lower pH can cause disruption or
dislodgement of scales formed from corrosion byproducts or protective scales, such as calcium carbonate.
Further Reading
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd Edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Change in finished water NOM
Description
Nanofiltration is a physical process that removes molecules from water. Nanofiltration can remove both
paniculate matter and dissolved compounds, including NOM. Thus, the NOM concentration entering the
distribution system is significantly reduced. Some NOM in finished water can help inhibit corrosion.
Further Reading
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Gushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
Colored water
Description
Nanofiltration can also result in a lowering of the pH of the water. The lower pH water will be more corrosive to
iron pipe in the distribution system. The corrosion will result in increased iron in the water, which can lead to
colored water problems.
Simultaneous Compliance Guidance Manual C-31 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
Further Reading
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
VonHuben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver:
AWWA.
AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and
Distribution. 3rd Edition. 553 pp. Denver: AWWA.
Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D. Smith, M.
LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance
Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357.
Denver: AwwaRF and AWWA.
Mays, L.W. 1999. Water Distribution Systems Handbook. 900pp. Denver: AWWA.
High iron
Description
Nanofiltration can also result in a lowering of the pH of the water. The lower pH water will be more corrosive to
iron pipe in the distribution system. Corrosion of iron pipe will result in increased iron in the water.
Further Reading
• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution
Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF.
Change in DBF concentration/composition
Description
Nanofiltration physically removes DBF precursors, reducing the formation of DBFs. Therefore, by installing
nanofiltration, systems can decrease TTHM and HAA5 levels in the plant and the distribution system.
Further Reading
• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver:
AWWA.
• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Pinhole leaks
Description
Nanofiltration can remove most larger particles and many smaller ones. This includes NOM, which has been
shown to inhibit pitting corrosion in copper piping.
Further Reading
Edwards, M., J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole leaks in
residential plumbing. Water Science and Technology. 49(2): 83-90.
Edwards, M., J.F. Ferguson, S. Reiber. 1994. The Pitting Corrosion of Copper. Journal of American
Water Works Association. 86(7): 74-91.
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution
Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF.
Simultaneous Compliance Guidance Manual C-32 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
INSTALLING GRANULAR ACTIVATED CARBON
The following impacts to your distribution system may result from installing granulated
activated carbon (GAC):
• Increased coliform and heterotrophic bacteria
The following references can provide further information about how to address this
impact. A brief description of the distribution system impact is provided in the table below.
• AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York:
McGraw-Hill.
• American Chemical Society. 1983. Treatment of Water by Granular Activated
Carbon. MJ. McGuire and I.H. Suffet (editors). Washington, D.C.: American
Chemical Society.
• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition.
278 pp. Denver: AWWA.
• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water
Transmission and Distribution. 3rd Edition. 553 pp. Denver: AWWA.
• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D.
Smith, M. LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R.
Gushing. 2000b. Guidance Manual for Maintaining Distribution System Water
Quality. AwwaRF Report 90798. Project #357. Denver: AwwaRF and AWWA.
• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
• Mays, L.W. 1999. Water Distribution Systems Handbook. 990 pp. Denver: AWWA.
• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp.
Denver: AWWA.
Refer to Section 4.1 for additional information on installing GAC.
Increased coliform and heterotrophic bacteria
Description
Heterotrophic bacteria can colonize GAC filters and can be shed in the filter effluent. The number of bacteria in
the effluent of GAC systems is frequently higher than influent levels. This problem is compounded when GAC
filters are operated in biologically active mode, where biological growth on the GAC filters is promoted.
Simultaneous Compliance Guidance Manual C-33 March 2007
For the Long Term 2 and Stage 2 DBF Rules
-------
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems
INSTALLING OZONE WITHOUT SUBSEQUENT BIOLOGICAL FILTRATION
The following impact to your distribution system may result from installing ozone
without subsequent biological filtration:
• Increased coliform and heterotrophic bacteria
The following references can provide information about how to address this impact. A
brief description of the distribution system impact is provided in the table below.
• Singer, P.C. (editor). 1999. Formation and Control of Disinfection By-Products in
Drinking Water. 424 pp. Denver: AWWA.
• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-
R-99-014.
• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous
Compliance Guidance Manual. EPA 815-R-99-011. August 1999.
• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition.
278 pp. Denver: AWWA.
• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water
Transmission and Distribution. 3rd Edition. 553 pp. Denver: AWWA.
• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.P. Noran, K.D. Mattel, D.
Smith, M. LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R.
Gushing. 2000b. Guidance Manual for Maintaining Distribution System Water
Quality. AwwaRF Report 90798. Project #357. Denver: AwwaRF and AWWA.
• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA.
• Mays, L.W. 1999. Water Distribution Systems Handbook. 990pp. Denver: AWWA.
• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp.
Denver: AWWA.
Refer to Section 5.2 for additional information on installing ozone without subsequent
biological filtration.
Increased coliform and heterotrophic bacteria
Description
Ozone reacts with NOM in water to destroys many DBF precursors. However, ozone breaks the NOM down into
smaller organic molecules that are readily used as a food source by microorganisms, referred to as assimilable
organic carbon (AOC). If ozone is followed by biological filtration, the AOC concentration can be significantly
reduced. However, if ozone is not followed by biological filtration, the AOC will pass into the distribution
system where it can be readily used by microorganisms. This will result in increased heterotrophic bacterial
growth and possibly higher coliform numbers and may cause nitrification in chloraminated systems.
Simultaneous Compliance Guidance Manual C-34 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix D
Tools for Evaluating Impacts of Treatment Changes on
Lead and Copper Rule Compliance
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
Appendix D
Tools for Evaluating Impacts of Treatment Changes on Lead and
Copper Rule Compliance
Currently, water systems work with their primacy agencies (primarily state regulatory
agencies) to ensure compliance with the LCR. The state establishes optimal water quality
parameters that the system must monitor, in addition to regulatory lead and copper tap sampling,
to evaluate compliance with the Rule. The system must maintain these water quality parameters
at specified levels and/or ranges to maintain optimal corrosion control treatment (OCCT). Water
systems must notify their primacy agency no later than 60 days after the addition of a new source
or implementation of a treatment or source water change; however, systems are encouraged to
provide notification to the State prior to any treatment change to minimize risks that the change
will adversely impact OCCT (40 CFR 141.8(b)(3)). Proposed revisions to the LCR would
require water systems to provide advanced notification to their primacy agency and to get
approval for intended changes in treatment or the addition of a new source that could increase
release and uptake of lead. This proposed revision would allow states and water systems to take
as much time as needed to consult about potential problems, allowing evaluations to be
completed that would strive to avoid or minimize potential problems with corrosion control and
ultimately ensure that OCCT is being maintained after the treatment change has been made.
Conducting evaluations of the potential impact that a proposed treatment change may have on
LCR compliance can provide information both parties can utilize in discussions of how best to
maintain OCCT in the system. This appendix provides a summary of various corrosion
assessment tools that can be used in these evaluations.
Corrosion assessment tools should be used prior to a treatment change to predict the
potential for causing metals release and uptake associated with the change. In cases where
metals release has already become a problem, these assessment tools can also be used to
determine where and why metals release is occurring and to test alternative corrosion control
strategies.
There are many types of corrosion assessment tools ranging from relatively inexpensive
data analyses to extensive pilot and partial system studies. For the purposes of this appendix,
corrosion assessment tools have been organized into the following categories:
• Desktop studies
• Water Quality Monitoring
- Expanded baseline monitoring
- Supplemental tap water quality monitoring
• Blending analysis
• Solubility models
• Laboratory and Field Testing
- Treatment simulation
- Pipe loop testing
- Coupon studies
- Electrochemical measurement techniques
Simultaneous Compliance Guidance Manual D-l March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
- Scale and solids analysis
- Partial system testing
These tools can be used in a progressive manner to evaluate potential impacts of lead
release and uptake by the water associated with a change in treatment or operations. For
example, a desktop study, which is based on review and evaluation of readily available data and
information, may be sufficient to understand the potential for metals release. However, in some
cases there may be system-specific conditions (e.g., unlined cast iron pipe, changes in secondary
disinfectant) that warrant additional study. In such cases, diagnostic tools such as pipe loop
studies or scale analysis could be used to help establish optimum water quality and treatment
conditions. In cases where the cause(s) of increased lead and/or copper release is not known,
other diagnostic tools such as supplemental tap water quality monitoring could be useful.
Ultimately, the system should select the appropriate corrosion assessment tool(s) for their
applications.
Exhibit D. 1 provides a summary of the assessment tools, their usefulness in terms of
assessing lead and copper release, and their relative costs. The sections that follow describe each
tool and identify their uses and limitations. A list of references where the reader can find
additional information is presented at the end of each section and in Chapter 7 of this guidance
document.
Simultaneous Compliance Guidance Manual D-2 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
Exhibit D.1 Summary of Corrosion Assessment Tools
Tool
Desktop studies
Expanded
baseline
monitoring
Supplemental
tap water quality
monitoring
Blending
analysis
Solubility
models
Treatment
Simulation
Pipe Loop
Studies
Coupon Studies
Electrochemical
Measurement
Techniques
Scale and Solids
Analysis
Partial System
Testing
Section
D.I
D.2.1
D.2.2
D.3
D.4
D.5.1
D.5.2
D.5.3
D.5.4
D.5.5
D.5.6
Description
Review of current and historical information
such as literature, data, expert opinion, and
analogous system experiences
Increased monitoring in the distribution
system for optimal water quality parameters
(pH, alkalinity, calcium, conductivity,
temperature, and corrosion inhibitors) and
other parameters (e.g., ORP) that may provide
useful information on metals release potential.
Includes LCR compliance sampling at more
sites and/or more frequently and water line
profiling at select sites
Predicting the water quality of multiple
sources blended in a distribution system
Using models to predict the thermodynamic
stability of a metal under specific water
quality conditions and evaluate the
mechanisms underlying scale development
and passivation.
Using models or conducting jar tests to
simulate the effects of treatment changes
Studies that measure metals release under
different water quality conditions.
Studies that utilize metal coupons to
determine metal loss and corrosion rates in a
given water quality.
Using instruments to measure the potential or
the current on the metal surface and determine
the corrosion rate
Analytical methods used to examine the
accumulated corrosion products on pipes.
Testing a corrosion treatment method on a
portion of the distribution system which has
been hydraulically isolated from the rest of
the system
Potential
Uses*
1,2
1,2,3
1,2,3
1,2,3
1,2,3
1
1,3
1,3
1,3
1,2,3
3
Relative
Cost
Low
Medium
Medium
-High
Low
Low
High
High
High
High
High
High
1 = To predict the impact of a change in treatment or operations on metals release
2 = To diagnose the cause and location of metals release
3 = To test the effectiveness of corrosion control alternatives
Simultaneous Compliance Guidance Manual
For the Long Term 2 and Stage 2 DBF Rules
D-3
March 2007
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
D.1 Desktop Studies
Description of Method
Desktop studies utilize current and historical information to document the extent,
magnitude, and possible causes of potential problems. By referencing a variety of information
sources, desktop studies can be used to 1) develop and assess treatment options and the
corresponding water quality changes that potentially can occur, 2) identify the secondary impacts
of those treatment and water quality changes, and 3) identify actions that will help to mitigate
those potential problems. Information sources for desktop studies can include the following:
• Literature reviews;
• Reviews of historical water quality, treatment, and modeling data;
• Review of standards and guidance documents;
• Expert opinions; and
• Consultation with, and analyses of data from other systems with similar water quality
and distribution systems (analogous systems).
Literature reviews of field and laboratory studies may help reveal corrosion mechanisms
and inter-relationships between lead and copper leaching and water quality conditions in the
system, and also identify possible corrosion prevention strategies. The AWWA Research
Foundation (AwwaRF) has published an overview of corrosion research (AwwaRF, 2007) and
EPA includes references to several historical corrosion studies in drinking water regulations and
guidance manuals. As part of a recent study, the American Water Works Association (AWWA,
2005b) summarized unintended consequences associated with changes in source water,
treatment, and operations and maintenance (O&M) practices on lead and copper release and
uptake in the distribution system. These unintended consequences include changes in corrosion-
related water quality parameters, changes to existing scales, and other corrosion-related impacts.
The study includes a checklist which can serve as a screening tool in identifying possible effects
of changes on LCR compliance.
Historical data collected by utilities, including treatment data, finished and distribution
system water quality and materials evaluations, existing LCR monitoring data, modeling results,
and results from special studies, can all be utilized in a desktop evaluation to identify potential
simultaneous compliance issues. Burlingame and Sandvig (2004) provide an example of how
one system evaluated historical lead and copper data to determine if changes in operations,
treatment, or source were impacting lead and copper levels.
Desktop studies can also incorporate a thorough review of regulatory standards and
associated guidance documents. The EPA has developed a guidance manual for selecting lead
and copper corrosion control strategies which incorporates information on secondary impacts of
various corrosion treatment approaches (USEPA 2003h).
Review of case studies of systems with similar water quality and treatment scenarios can
provide insight into potential problems associated with implementation of corrosion control
treatment and the ability to maintain compliance with regulations. Appendix B of this guidance
manual provides numerous case studies showing how different water systems have addressed
Simultaneous Compliance Guidance Manual D-4 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
simultaneous compliance and operational issues. AWWA's Water Industry Technical Action
Fund collected lead and copper data along with other water quality data such as, alkalinity,
calcium, and the type of corrosion inhibitor used for 400 US water systems (AWWA, 1993).
Systems could use this data to evaluate the effectiveness of corrosion inhibitors for systems with
similar water quality.
Uses and Limitations
Desktop studies can be used by systems to characterize the potential for corrosion
problems to occur when contemplating changes in water quality and/or treatment. Desktop
studies are also a relatively inexpensive method for screening a number of potential solutions to
a corrosion problem. Desktop studies provide a way for systems to learn from the experience of
others and focus efforts on the most effective techniques.
In many cases, results from desktop studies can be sufficient for understanding potential
compliance concerns associated with a change in treatment or operations. Desktop studies may
be limited however, in situations where supply, treatment, and distribution system configurations
and operations are complex and/or unusual. In these situations, desktop studies could be used in
combination with other corrosion assessment tools. When evaluating corrosion control treatment
options, systems should consider using desktop studies in combination with other tools to
identify any system-specific treatment issues.
References
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water
Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver:
AwwaRF.
AWWA. 1993. Initial Monitoring Experiences of Large Water Utilities Under EPA's
Lead and Copper Rule. Denver: WITAF.
AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper
Rule Corrosion Control Treatment. Denver: AWWA.
AwwaRF. 2007. Distribution System Corrosion and the Lead and Copper: An Overview
of AwwaRF Research. AwwaRF Special Report. Denver: AwwaRF.
Burlingame, G.A. and A. Sandvig. 2004. How to Mine Your Lead and Copper Data.
Opflow. 30(6): 16-19.
Economic and Engineering Services, Inc. and Illinois State Water Survey. 1990. Lead
Control Strategies. Denver: AwwaRF and AWWA.
Hecht, P.M., and E.A. Turner. 2004. Washington Aqueduct Desktop & Flow-Through
Study. Presented at Getting the Lead Out: Analysis & Treatment of Elevated Lead Levels
in DC's Drinking Water at the 2004 AWWA WQTC.
Simultaneous Compliance Guidance Manual D-5 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
USEPA. 2003h. Revised Guidance Manual for Selecting Lead and Copper Control
Strategies. Office of Water. EPA 816-R-03-001. March, 2003.
D.2 Water Quality Monitoring
This section describes two types of water quality monitoring tools, expanded baseline
monitoring of the distribution system and supplemental monitoring of corrosion products at the
tap.
D.2.1 Expanded Baseline Monitoring
Description of Method
The LCR requires systems to monitor basic water quality parameters in the distribution
system. Depending on the corrosion control treatment, some combination of the following
parameters is typically required: pH, alkalinity, calcium, conductivity, temperature, and the
corrosion inhibitor concentration. Results from this and other monitoring programs can provide
useful information on the state of corrosion within the distribution system. For example,
bacteriological data from compliance monitoring for the Total Coliform Rule (TCR) can help
systems identify areas likely to suffer from microbial induced corrosion. Sampling for water
quality parameters at more locations and performing it at more frequent intervals can provide
better information on potential trouble spots in the systems. Also, systems can obtain a better
spatial representation of the level of these parameters and be able to more accurately assess the
potential for metals release in various parts of the system.
Additional water quality and corrosion parameters may be incorporated into baseline
monitoring such as measurements of oxidation reduction potential (ORP). ORP is the potential
for transfer of electrons between chemical species and is measured in volts (V), millivolts (mV),
or Eh (lEh = ImV). The ORP of the water can impact the metal oxidation rates and the nature
of scales that form on the interior of piping and fittings, affecting metals release.
Kirmeyer et al. (2002) present detailed corrosion control monitoring protocols including
both proactive and reactive monitoring objectives.
Usefulness and Limitations
Expanded baseline monitoring can be used to identify areas of a distribution system that
have potentially corrosive waters and find areas where a corrosion inhibitor is not performing
effectively. An on-going distribution system expanded baseline water quality monitoring
program can provide an 'early-warning' of potential system-wide problems that may occur after
a treatment or operational change, as well as identify the occurrence of more localized water
quality problems. Results from this type of monitoring program can also provide a more
complete assessment of the system for evaluating the impact of future treatment changes.
References
Simultaneous Compliance Guidance Manual D-6 March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
AWWA 2005a. Managing Change and Unintended Consequences: Lead and Copper
Rule Corrosion Control Treatment. Denver: AWWA.
Kirmeyer, G.J., J. Clement, and A. Sandvig. 2000a. Distribution System Water Quality
Changes Following Implementation of Corrosion Control Strategies. AwwaRF Report
90764. Project #157. Denver: AwwaRF.
Kirmeyer, G.J., M. Friedman, K. Mattel, G. Thompson, A. Sandvig, J. Clement, and M.
Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality.
Denver: AwwaRF and AWWA.
USEPA 2002c. Lead and Copper Monitoring and Reporting Guidance for Public Water
Systems. Office of Water. EPA 816-R-02-009.
D.2.2 Supplemental Tap Water Quality Monitoring
Description of Method
Supplemental tap water sampling can provide a more complete picture of the occurrence
of lead and copper levels at the tap, beyond the information available through regulatory
monitoring required by the LCR. Supplemental tap water quality sampling includes collecting
LCR samples at more sites and at a greater frequency than required. In addition to traditional
LCR sampling, sequential samples can be collected from customer's taps and analyzed to help
determine the source of the lead (i.e., whether it is originating from faucets, meters, soldered
joints, service lines, plumbing fittings, or other locations). This method is referred to as "water
line profiling" or "sequential sampling." Results from profiling can also provide useful
information on the relationship of lead and copper corrosion products to other water quality
parameters. Analyses of particulate versus dissolved lead can provide information on the
possible mechanisms for lead release (e.g., soluble release from metals surfaces or paniculate
metals release from scales).
Uses and Limitations
Supplemental tap water quality monitoring can provide data that can be used to evaluate
the potential impact of treatment and operational changes on lead and copper levels at the tap,
and consequently, compliance with the LCR. Additional tap monitoring data on lead and copper
levels can provide more confidence in the conclusions with respect to potential impacts system-
wide.
Water line profiling can provide diagnostic information on the location of metals release.
Results from profiling can also provide useful information on the relationship of lead and copper
corrosion products to other water quality parameters. Analyses of parti culate versus dissolved
lead can provide information on the possible mechanisms for lead release (e.g., soluble release
from metals surfaces or particulate metals release from scales).
Because samples are collected at the tap, supplemental monitoring programs require
significant cooperation from customers.
Simultaneous Compliance Guidance Manual D-7 March 2007
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
References
AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper
Rule Corrosion Control Treatment. Denver: AWWA.
Boyd, G.R., GJ. Pierson, GJ. Kirmeyer, M. Britton, and RJ. English. 2006. Pb release
from end-use plumbing components. Proceedings of Water Quality Technology
Conference. November 5-9. Denver: AWWA.
Estes-Smargiassi, S., J. Steinkrauss, A. Sandvig, and T. Young. 2006. Impact of Lead
Service Line Replacement on Lead Levels at the Tap. In Proceedings AWWA Annual
Conference and Exposition. San Antonio: AWWA. June, 2006.
Estes-Smargiassi, S., and A. Cantor. 2006. Lead Service Line Contributions to Lead at
the Tap. In Proceedings AWWA Water Quality Technology Conference. Denver:
AWWA. November 2006.
Giani, R., M. Edwards, C. Chung, and J. Wujek. 2004. Lead Profiling Methodologies
and Results. Presented at Getting the Lead Out: Analysis & Treatment of Elevated Lead
Levels in DC's Drinking Water at the 2004 A WWA WQTC. Proceedings of A WWA Water
Quality Technology Conference. Denver: AWWA.
Kirmeyer, G.J., B.M. Murphy, A. Sandvig, G. Korshin, B. Shaha, M. Fabbricino, and G.
Burlingame. 2004b. Post Optimization of Lead and Copper Control Monitoring
Strategies. AwwaRF Report 90996F Project #2679. Denver: AwwaRF.
D.3 Blending Analysis
Description of Method
Blending analyses can predict the characteristics of the water when two sources are
blended in the distribution system and help determine if corrosive conditions might result. While
the prediction of some key corrosion parameters can be done using simple mass balance
equations, evaluation of others could benefit from the use of computational software. One useful
tool is the Rothberg, Tamburini & Winsor Blending Application Package 4.0 (AWWA 200 la).
Uses and Limitations
Blending analyses can be particularly useful if a water system is considering using an
alternative source to comply with a regulation. As with any modeling exercise, the output of the
model depends on the accuracy of the input parameters, and users will need a certain level of
expertise and understanding of water chemistry and treatment.
References
AWWA. 2001a. The Rothberg, Tamburini & Winsor Blending Application Package 4.0.
Simultaneous Compliance Guidance Manual D-8 March 2007
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
AWWA Catalog Number 53042.
Taylor, J.S., J.D. Dietz, A.A. Randall, S.K. Hong, C.D. Norris, L.A. Mulford, J.M.
Arevalo, S. Imran, M. Le Puil, S. Liu, I. Mutoti, J. Tang, X. Xiao, C. Cullen, R.
Heaviside, A. Mehta, M. Patel, F. Vasquez, and D. Webb. 2005. Effects of Blending on
Distribution System Water Quality. AwwaRF Report 91065F. Project #2702. Denver:
AwwaRF.
D.4 Solubility Models
Description of Method
Chemical solubility models can predict the thermodynamic stability of a given metal
under specific water quality conditions and can be used to evaluate the mechanisms underlying
scale development and passivation. These models can help in predicting potential corrosion
problems and may be especially useful for lead corrosion. There are several non-proprietary and
commercially available solubility models, including CORRODE (Edwards and Reiber 1997 a, b)
and PHREEQCI (United States Geological Survey).
Uses and Limitations
Solubility models are based on equilibrium kinetics, and may not take into account non-
equilibrium conditions and variations in system conditions (particulate lead release, water usage,
scale accumulation, etc.) that would impact metals release in the field. A certain level of
expertise and understanding of equilibrium chemistry and solubility constants would be needed
in order to effectively use these models and evaluate their results properly.
References
Butler, J.N. with a Chapter by David Cogley. 1998. Ionic Equilibrium. Solubility andpH
Calculations. New York: Wiley-Interscience.
Edwards, M. and S. Reiber. 1997'a. A General Framework for Corrosion Control Based
on Utility Experience. AwwaRF Report 90712A. Project #910. Denver: AwwaRF.
Edwards, M. and S.H. Reiber. 1997b. PredictingPb andCu corrosion by-product release
using CORRODE software. AwwaRF Report 90712B. Project #910. Denver: AwwaRF.
Parkhurst, D.L. and C.A.J. Appelo. 1999. User's guide toPHREEQC (Version2)—A
computer program for speciation, batch-reaction, one-dimensional transport, and inverse
geochemical calculations. 310 pp. Water Resources Investigations Report 99-4259. U.S.
Geological Survey.
Simultaneous Compliance Guidance Manual D-9 March 2007
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
D.5 Laboratory and Field Studies
Whereas desktop studies, modeling, and monitoring can provide useful tools for
predicting the impact of treatment changes with respect to corrosion, laboratory and field studies
can be used to address site-specific issues and in some cases, measure actual changes in
corrosion parameters including metals release. This section builds on previous sections by
providing information on the following corrosion assessment tools:
• Treatment simulation
• Pipe loop testing
• Coupon studies
• Electrochemical measurement techniques
• Scale and solids analysis
• Partial system testing
D.5.1 Treatment Simulation
Description of Method
Treatment simulation models can used to evaluate the effect of certain treatment changes
on corrosion parameters and can be useful in identifying the best combination of treatment
scenarios to achieve simultaneous compliance. For example, the Water Treatment Plant Model
(USEPA 2001i) includes data and alternative treatment processes to assist utilities in achieving
optimized conditions. In cases where models may not be sufficient, jar testing can show how
treatment changes can alter finished water quality conditions as they relate to corrosion potential.
Uses and Limitations
Jar tests and treatment simulation models are very useful in determining the impact of a
treatment change on water quality at the treatment plant. They do not, however, take into account
changes as water moves through the distribution system and site specific factors such as
microbiological activity and interactions of the water with different pipe material.
References
AWWA. 2000. Operational Control of Coagulation and Filtration Processes. 2nd
Edition. AWWA Manual M37. pp. 1-34. Denver: AWWA.
AwwaRF. 1999. Distribution System Water Quality Changes Following Corrosion
Control Strategies. Denver: AwwaRF.
USEPA. 20011. Water Treatment Plant Model. Version 2.0. Developed by the Center for
Drinking Water Optimization, University of Colorado - Boulder and Malcom Pirnie, Inc.
May, 2001.
Simultaneous Compliance Guidance Manual D-10 March 2007
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
D.5.2 Pipe Loop Studies
Description of Method
Pipe loop studies are intended to simulate corrosion in the consumer's plumbing system
and allow for direct measurement of metal release. Pipe loop material can include 1) pipes or
pipe sections which reflect actual distribution system conditions with respect to corrosion scale
(e.g., pipes extracted from the distribution system), 2) new lead, copper, and/or brass materials
representative of new construction, and 3) lead pipes coupled with copper to represent areas
where lead service line replacement has occurred.
Pipe loops are typically designed as flow-through or recirculating systems. In flow
through pipe loops, water flows through the pipe a single time as in a real system and is
discharged to waste. Recirculating pipe loops recirculate the same batch of water through the
pipes. In both types, water can be stagnated for periods of time to represent water use patterns.
Water from the pipe loops can be collected and analyzed for a variety of water quality
parameters including lead, copper, and other corrosion products. Pipes should be conditioned
prior to water quality changes to achieve a stable rate of metals leaching.
Uses and Limitations
Pipe loops are well suited for determining how distribution or plumbing materials will
respond to changes in water quality and to evaluate potential corrosion control strategies. One
advantage is that pipe loops closely simulate actual distribution systems and the conditions under
which corrosion occurs. One disadvantage is that these studies can require a relatively long time
to conduct and the setups are more expensive than other corrosion assessment techniques. The
AwwaRF report titled Internal Corrosion of Water Distribution Systems (AwwaRF and DVGW-
Technologiezentrum Wasser 1996) contains a thorough description of assessment technologies
for corrosion control studies, including a discussion of the benefits and drawbacks of pipe loop
studies. AwwaRF reports (Economic and Engineering Services, Inc. and Illinois State Water
Survey 1990; Kirmeyer et al. 1994) describe a standard protocol for a pipe loop system for
evaluating corrosion control treatment options.
References
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water
Distributio
AwwaRF.
Distribution Systems. 2nd Edition. AwwaRF Report 90508. Project #725. Denver:
Economic and Engineering Services, Inc. and Illinois State Water Survey. 1990. Lead
Control Strategies. Denver: AwwaRF and AWWA
Kirmeyer, G.J., A.M. Sandvig, G.L. Pierson, and C.H. Neff 1994. Development of a Pipe
Loop Protocol for Lead Control. AwwaRF Report 90650 Project #604. Denver:
AwwaRF.
Simultaneous Compliance Guidance Manual D-l 1 March 2007
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
D.5.3 Coupon Studies
Description of Method
Coupon techniques are used to evaluate the corrosion of a given distribution system metal
under specific conditions. Coupon techniques place a coupon in water either in a pilot testing
apparatus or in the distribution system. The coupons are sacrificed periodically for total weight
loss measurements.
Traditional coupon techniques have involved flat metal coupons mounted in a flow
stream including methods ASTM D2688-83 method B, ASTM Gl-81, ASTM G46-76, and the
Water Research Center Coupon Rig. Other techniques have been developed that use actual pipe
lengths including ASTM D2688-83 method C, Modified ISWS Coupon sleeve tester, Corps of
Engineers Research Lab tester, Ringsaulen protocol, and the TZW Karlsruhe protocol. See
Table 9-3 in the publication, Internal Corrosion of Water Distribution Systems fAwwaRF and
DVGW-Technologiezentrum Wasser 1996), for a summary description of these techniques.
Usefulness and Limitations
Weight loss for lead coupons is generally very low, so interpretation of weight loss data
using these methods may be challenging. Coupon techniques are best suited for determining
likely corrosion rates that can be expected for given water quality conditions and a given metal,
and can be useful in selecting new materials to be used for distribution system expansion or
rehabilitation. Weight loss measurements have not always correlated well with measurements of
lead release in water samples (Schock 1996). Therefore, the usefulness of this technique for
evaluating LCR compliance issues related to lead may be limited, however, they may be of value
in evaluating copper corrosion and copper release.
References
ASTM D2688-83 Method B. 1983a. Standard Test Methods for the Corrosivity of Water
in the Absence of Heat Transfer (Weight Loss Protocol). Philadelphia: American Society
for Testing and Materials.
ASTM D2688-83 Method C. 1983b. Standard Test Methods for the Corrosivity of Water
in the Absence of Heat Transfer (Machined Nipple Test). Philadelphia: American Society
for Testing and Materials.
ASTM G46-76. 1976. Recommended Practise for the Examination and Evaluation of
Pitting Type Corrosion. Philadelphia: American Society for Testing and Materials.
ASTM Gl-81. 1981. Recommended Practise for Preparing, Cleaning and Evaluating
Corrosion Test Specimens. Philadelphia: American Society for Testing and Materials.
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water
Distribution Systems. 2nd Edition. AwwaRF Report 90508. Project #725. Denver:
AwwaRF.
Simultaneous Compliance Guidance Manual D-12 March 2007
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
Schock, M. 1996. Corrosion Inhibitor Applications in Drinking Water Treatment:
Conforming to the Lead and Copper Rule. Presented atNACE Corrosion 1996
Conference.
D.5.4. Electrochemical Measurement Techniques
Description of Method
Corrosion reactions are fundamentally electrochemical reactions which involve the
transfer of electrons. Electrochemical methods use different tools and measurement techniques
to measure this electron transfer and derive the underlying corrosion rate of a metal. For
example, potentiodynamic scans rely on artificial perturbation of the corroding surface by
impressing a current on it. Resulting changes in surface potential are measured and used to
derive the corrosion rate.
Electrochemical impedance spectroscopy is a relatively new technique that is well suited
for drinking water applications. It works similarly to other techniques in that an impressed
current is applied to the surface and the resulting potential is measured. It differs from other
techniques in that the current is an alternating current instead of a direct current. The results are
analyzed to create a model of the corroded surface. This can give a picture of all the components
of a corroding surface such as the polarization resistance of the surface and the presence of a
passivating layer.
Other electrochemical techniques that may be useful for online monitoring of corrosion
include electrical resistance, linear polarization, and electrochemical noise. The 1996 report,
Internal Corrosion of Water Distribution Systems (AwwaRF and DVGW-Technologiezentrum
Wasser 1996), provides a summary of electrochemical corrosion assessment methodologies
including their applications, precision, and equipment requirements.
Uses and Limitations
Unlike other evaluation tools which measure metals release, electrochemical techniques
provide an instantaneous measurement of the underlying corrosion rate of the metal. They have
been shown to be very useful for assessing uniform corrosion of metals such as lead, copper,
zinc, and brass (AwwaRF and DVGW-Technologiezentrum Wasser 1996). Over the past decade,
there has been substantial development of these techniques, making them more accessible to
systems as an operational tool. Advantages of electrochemical techniques include their speed,
ease of measurement using commercially available software, and the fact the analyses can be
made without changing the test specimen.
Electrochemical methods may be unsuitable for surfaces subject to heavy pitting (i.e.
mild steel or iron). These techniques do not reproduce easily across different conditions and are
thus more suitable for relative comparisons of corrosion rate rather than measurement of absolute
values.
Simultaneous Compliance Guidance Manual D-13 March 2007
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
References
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water
Distributu
AwwaRF.
Distribution Systems. 2nd Edition. AwwaRF Report 90508. Project #725. Denver:
Cottis, R.A., S. Turgoose, and R. Newman. 1999. Corrosion Testing Made Easy:
Electrochemical Impedance and Noise. Houston: National Association of Corrosion
Engineers.
Kirmeyer, G.J., B.M. Murphy, A. Sandvig, G. Korshin, B. Shaha, M. Fabbricino, and G.
Burlingame. 2004b. Post Optimization of Lead and Copper Control Monitoring
Strategies. AwwaRF Report 90996F Project #2679. Denver: AwwaRF.
D.5.5 Scale and Solids Analysis
Description of Method
Analysis of pipe scales and corrosion solids can reveal useful information on the
corrosion process itself and effectiveness of various corrosion control strategies. Techniques
such as X-ray emission spectroscopy, X-ray diffraction, X-ray fluorescence, and scanning
electron microscopy can provide information on the elemental composition of the corrosion
scales. Some analytical techniques give detailed information on chemical bonding and structure
at the surface of the corrosion deposits which is helpful in estimating the probability of
unintended adverse consequences of treatment or water quality changes (Rego and Schock
2007).
Uses and Limitations
Pipe surface analyses using the techniques described above can be useful for determining
the composition of corrosion scale and corrosion products, and the effectiveness of current
treatment practices. Characterization of the corrosion scale can provide insight into the
mechanisms behind metals release and how water quality changes may alter that existing scale,
potentially resulting in increased metals release. These techniques can also give information on
any passivating or barrier layers that can protect pipes from further corrosion. Currently, these
methods are relatively expensive and the results can be difficult to interpret. As such, laboratory
analyses of corrosion products are typically used for special studies.
References
ASTM D934-80. 2003. Standard Practices for Identification of Crystalline Compounds in
Water Formed Deposits by X-Ray Diffraction. Philadelphia: American Society for
Testing and Materials.
Simultaneous Compliance Guidance Manual D-14 March 2007
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
Clement, J., A. Sandvig, V. Snoeyink, W. Kriven, and P. Sarin.1998. Analyses and
Interpretation of the Physical, Chemical, and Biological Characteristics of Distribution
System Pipe Scales. In Proceedings of the Water Quality Technology Conference.
Denver: AWWA.
Rego, C.A. and M.R. Schock. 2007. Case Studies in the Integrated Use of Scale Analyses
to Solve Lead Problems. In Proceedings of Distribution System Research Symposium.
Denver: AWWA.
Smith, S.E., J.S. Colbourne, D.M. Holt, BJ. Lloyd, and A. Bisset. 1997. An Examination
of the Nature and Occurrence of Deposits in a Distribution System and their effect on
Water Quality. In Proceedings of the AWWA Water Quality Technology Conference.
Boston, 17-21 November 17-21. Denver: AWWA.
D.5.6 Partial System Testing
Description of Method
In partial system testing, a corrosion control treatment method is tested on a small part of
the distribution system which has been hydraulically isolated from the rest of the system and
where water quality conditions can be changed and the impact of that change evaluated. A
variety of additional corrosion assessment tools can be used during partial system testing,
including:
• Supplemental water quality monitoring from residential taps to evaluate changes in
metals release;
• Increased baseline monitoring of key water quality parameters;
• Inserting coupons into the distribution system that can be removed and analyzed;
• Electrochemical monitoring using on-line devices; and
• Removal of piping materials for evaluation of the corrosion scale.
An outreach program should be in place to the customers in that section of the distribution
system informing them of the test and any changes which they might experience.
Uses and Limitations
A partial system test can be very useful in examining system specific issues which might
not be obvious from pipe loop tests or other laboratory techniques. For example, partial system
tests can help determine whether a given water quality change might lead to red water incidents
within the system.
A partial system test, however, does not guarantee that problems will not occur in the rest
of the system as there can still be differences in piping material, water temperatures, soil
conditions, pipe age and other variables. A partial system test will also require isolating that part
of the system and communicating closely with customers in that portion of the system. It may
also require setting up temporary chemical feed facilities, which can be quite expensive and
difficult to control operationally due to fluctuations in flow.
Simultaneous Compliance Guidance Manual D-15 March 2007
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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance
References
AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water
Distribution Systems. 2nd Edition. AwwaRF Report 90508. Project #725. Denver:
AwwaRF.
Kirmeyer, G.J., J. Clement, and A. Sandvig. 2000a. Distribution System Water Quality
Changes Following Implementation of Corrosion Control Strategies. AwwaRF Report
90764. Project #157. Denver: AwwaRF.
USEPA. 1992b. Lead and Copper Rule Guidance Manual, Vol. II: Corrosion Control
Treatment. Prepared by Malcolm Pirnie, Inc. & Black & Veatch. September 1992.
Simultaneous Compliance Guidance Manual D-16 March 2007
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Appendix E
Innovative Management Tools for Achieving Simultaneous
Compliance
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Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance
Appendix E
Innovative Management Tools for Achieving Simultaneous
Compliance
Systems simultaneously complying with the Long Term 2 Enhanced Surface Water
Treatment Rule (LT2ESWTR), Stage 2 Disinfectants and Disinfection Byproducts Rule (DBPR),
and other drinking water regulations may benefit from a broader, more holistic approach to water
system management. Therefore, EPA and other organizations are developing integrated, source-
to-tap management programs to assist water systems. These programs can provide a framework
within which water systems can identify simultaneous compliance concerns, prioritize them, and
adopt approaches to ensure that they will be in compliance with numerous regulations at the
same time.
This appendix identifies existing and developing programs that can help water systems
comply with regulations and produce consistently high quality water. These programs include
performance-driven and integrated management approaches that consider treatment processes
and operating practices throughout the entire water system. Systems are encouraged to consult
with primacy agencies and other systems with similar treatment facilities and water quality to aid
in carrying out these programs.
Performance-Driven Optimization Programs
Several programs have been developed for water systems to optimize treatment plant
performance and distribution system management. This section briefly describes these programs
including references for more detailed information.
Partnership for Safe Water
The Partnership for Safe Water is a voluntary program organized collaboratively amongst
EPA, AWWA and other drinking water organizations to optimize water treatment plant
performance above and beyond regulatory requirements. The Partnership has provided a
successful approach for systems to improve turbidity removal in their treatment plants and
reduce microbial risks as addressed in the surface water treatment rules. The Partnership's
Information Center, (http://www.awwa.org/science/partnership/InfoCenter/) includes self-
assessment checklists, sample reports and fact sheets to help a water system get started.
QualServe
QualServe is a continuous quality improvement program that helps utilities to improve
overall service using a self-assessment tool, a peer review process, and a benchmarking
clearinghouse. The self-assessment tool is a survey of utility employees to gauge their opinions
and get their buy in and support for improvements. The peer review involves an on-site visit and
evaluation by a volunteer team of peers from other utilities. Benchmarking is used to track
utility performance and compare it to other utilities, thereby learning from their experiences.
Additional information can be found on AWWA's website
(http://www.awwa. org/science/qualserve/).
Simultaneous Compliance Guidance Manual E-l March 2007
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Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance
Areawide Optimization Program
An area-wide optimization program (AWOP) is a multi-state effort in which states work
together to develop and implement individual state programs to optimize particle removal and
disinfection capabilities of conventional surface water treatment plants in each state
(http://www.asdwa.org/index. cfm?fuseaction=Page.viewPage&pageID=523). A WOP is
designed to assist water systems work toward optimizing their existing treatment processes in an
effort to increase public health protection. While originally developed to address microbial
contaminants, AWOP has expanded beyond the original tools and is an ever-changing and ever-
growing program that now addresses both microbial contaminants and disinfection byproducts in
surface water systems. Initial steps are also being taken to investigate how to extend the
optimization concept to ground water systems. More information is available at the Association
of State Drinking Water Administrators (ASDWA) website listed in this paragraph.
Microbial and DBF Comprehensive Performance Evaluations
A comprehensive performance evaluation (CPE) is the evaluation phase of EPA's
Composite Correction Program. A Composite Correction Program is a systematic,
comprehensive procedure that identifies and corrects a unique combination of factors to improve
performance at filtration plants using existing facilities. CPEs are designed to identify and
correct limiting factors in the design, operation, maintenance, and administration of public water
systems that prevent compliance with drinking water regulations and optimized water system
operation. CPEs help systems prioritize ways to improve water system operation, and often
provide options without significant capital improvements as the highest priority option. CPEs
are designed to ensure that water systems consistently produce high quality drinking water.
While CPEs have primarily addressed pathogen control, efforts are underway to develop
a CPE methodology that addresses DBP control. A CPE for microbes or disinfection byproducts
(DBFs) consists of three components: performance assessment, major unit process evaluation,
and identification of factors that are limiting performance. The performance assessment
component determines a facility's status in achieving compliance for microbial and DBP
compliance requirements and performance goals and verifies the extent of any performance
problems at the plant. The major unit process evaluation determines if the various key existing
treatment processes in the plant, if properly operated, are of sufficient size to meet microbial and
DBP performance goals at the plant's current peak instantaneous operating flows. The last and
most significant component of a CPE is the identification of factors that limit the plant's
performance. CPEs are often conducted with the aid of primacy agency personnel or
consultants.
Simultaneous Compliance Guidance Manual E-2 March 2007
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Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance
For more information on CPEs, please see:
Association of State Drinking Water Administrators. 2005. Total System Optimization - How Does it Relate to
AWOP? Area-Wide Optimization Program News. 2(1). March 2005. Contact Alison Dugan at
dusan.alison(q),epa.gov or Larry DeMers at LDemersCO&.aol.com.
http://www.asdwa.org/index.cfm?fuseaction=Page.viewPage&pageID=523
Center for Drinking Water Optimization Page (University of Colorado at Boulder)
http://bechtel.colorado.edu/cdwo/Welcome.html
EPA's Drinking Water Academy Web site has numerous courses on conducting CPEs.
h ttp ://www. epa. sov/safewater/dwa/course-pwsoper. html
USEPA. 1998a. Handbook: Optimizing Water Treatment Plant Performance Using the Composite Correction
Program. EPA 625/6-91/027. http://www.eDa.eov/ORD/NRMRL/vubs/625691027/625691027.htm
Hegg, B.A. and L.D. DeMers. 2003. Performance Based Training: A Proven Approach to Improve Water
Treatment Plant Performance. Presented at American Water Works Annual Conference. Anaheim, California.
(June 15-19, 2003).
Jeschke, Rick, P.E. Plant Optimization at North Table Mountain Water and Sanitation District. Presented at the
2004 Joint Annual Conference of the Rocky Mountain Section of the American Water Works Association and
the Rocky Mountain Water Environment Association. Grand Junction, Colorado.
http://www.rmwea.ors/tech j>apers/Admin-finance/NTM_PPT_Pres.ppt
Kentucky Division of Water. Area Wide Optimization Program.
http://www.water.kv.sov/dw/profi/awop/default.htm
Swanson, Warren J., P.E. Assessing Plant DBF Performance Using the DBP-CPE. Presented at the 2004 Joint
Annual Conference of the Rocky Mountain Section of the American Water Works Association and the Rocky
Mountain Water Environment Association. Grand Junction, Colorado
http://www.rmwea.org/tech_papers/Admin-finance/DBPCPE_final.ppt
USEPA. 2004c. The Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR) Implementation
Guidance. (Appendix C) EPA 816-R-04-008.
USEPA. 2002c. Comprehensive Performance Evaluation (CPE): The Basics (Brochure). (EPA 816-F-01-020).
November 2002.
USEPA. 1999d. Guidance Manual for Compliance with the Interim Enhanced Surface Water Treatment Rule:
Turbidity Provisions. EPA 815-R-99-010.
USEPA. 1998. CPE Training CD Optimizing Water Treatment Plant Performance Using the Composite
Correction Program. EPA 625/6-91/027.
USEPA. 1998. Introduction to Comprehensive Performance Evaluations. EPA/625/C-01-011.
USEPA. Area Wide Optimization Program, http://www.epa.gov/reg3wapd/drinkingwater/optimization/
Simultaneous Compliance Guidance Manual E-3 March 2007
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Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance
Integrated Management Systems
It can be challenging for water systems to consider the impacts of specific management
or operations decisions on their entire water system. Efforts have been made to develop or adopt
management programs that consider the entire water system. For example, ISO 9000 addresses
general quality management issues, ISO 14001 focuses on protection of the environment, and
HACCP addresses drinking water safety to the consumer. Most of these programs serve as
frameworks that managers can use to tailor a source-to-tap management program addressing
issues and concerns specific to their water system. Because this approach is holistic (source-to-
tap), such programs can serve as effective ways to consider simultaneous compliance issues.
Integrated management systems are becoming a new trend in the water industry where these
programs are considered in an integrated manner as one quality assurance system that covers all
business management aspects, including general quality management (ISO 9000), protection of
the environment (ISO 14001), drinking water safety to the user (HACCP), and worker health and
safety. The benefit of implementing one integrated system is that only one audit would be
required and utility staff will implement only one set of policies and procedures (Mattel et al.
2006). The AwwaRF report, Application of HACCP for Distribution System Protection (Martel
et al. 2006) describes utility experiences with implementing integrated management systems.
This section briefly describes these management programs that, if used properly, could help a
system achieve simultaneous compliance.
Hazard Analysis and Critical Control Point
The Hazard Analysis and Critical Control Point (HACCP) program is an integrated risk
management approach that examines and assesses potential sources of contamination to a
process and develops control measures to mitigate these risks. HACCP has been used by the
U.S. Food and Drug Administration for years, and has become an accepted management practice
internationally to ensure the safety of food. Recent research indicates that HACCP principles
may be successfully applied to drinking water systems (Martel et al. 2006). This information
may then be used by drinking water systems to reduce the risk of contamination to the general
public. A HACCP Plan can be created and implemented by utility staff with appropriate
knowledge of the chemical, physical, and microbiological hazards in water supplies, and the
control measures used to manage them. Although outside experts are sometimes utilized as
advisors to the HACCP team, development of the HACCP Plan should be driven by utility staff
as successful implementation of the HACCP Plan requires buy-in and support at all levels of the
organization.
Seven basic principles are employed: hazard analysis; critical control point identification;
establishing critical limits; monitoring procedures; corrective actions; verification procedures;
and record-keeping and documentation. If a deviation occurs that indicates a loss of control, the
water system detects the deviation and takes the appropriate, defined steps to reestablish control
in a timely manner and ensure that potentially contaminated water does not reach the consumer
and cause compliance problems with one or more regulation.
Simultaneous Compliance Guidance Manual E-4 March 2007
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Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance
For additional information on HACCP, please refer to the following resources:
AIChE. 2000. Guidelines for Chemical Process Quantitative Risk Analysis, Second Edition. Wiley.
Dewettinck T., E. Van Houtte, D. Geenens, K. Van Hege, and W. Verstraete. 2001. HACCP (Hazard
Analysis and Critical Control Points) to Guarantee Safe Water Reuse and Drinking Water Production—
a Case Study. Water Science & Technology. 43(12): 31-8.
Martel, K., G. Kirmeyer, A. Hanson, M. Stevens, J. Mullenger, and D. Deere. 2006. Application of
HACCP for Distribution System Protection. AwwaRF Project #2856. Denver, CO: AwwaRF.
Mullenger, J., G. Ryan, and J. Hearn. 2002. A Water Authority's Experience with HACCP. Water
Supply. 2(5-6): 149-155. ©© IWA Publishing.
U.S. Food and Drug Administration. 1997. Hazard Analysis and Critical Control Point Principles and
Application Guidelines. http://www.cfsan.fda.gov/~comm/nacmcfp.html
U.S. Food and Drug Administration Website. http://www.cfsan.fda.sov/~lrd/haccp.html
World Health Organization. 2004. Water Treatment and Pathogen Control: Process Efficiency in
Achieving Safe Drinking Water. Edited by M.W. LeChevallier and K.K. Au. ISBN: 1 84339 069 8.
Published by IWA Publishing, London, UK.
World Health Organization. 2004. Guidelines for Drinking Water Quality, 3rd Edition. Geneva,
Switzerland. World Health Organization.
http://www. who. int/water_sanitation_health/dwq/gdwq3rev/en/index.html
ISO 9001 and 14001
The International Organization for Standardization (ISO) is the internationally recognized
source of standards that are commonly applied in Europe, Australia, and Asia. Two ISO
Standards commonly employed by water utilities include ISO Standards 9001 and 14001. ISO
Standard 9001 defines a Quality Management System that demonstrates the ability of an
organization to consistently provide products and services that meet customer needs, regulatory
requirements and internal goals. ISO Standard 14001 provides management system standards
that businesses, including drinking water systems, may use to minimize adverse impacts on the
environment, and to continually improve environmental performance, enabling them to
simultaneously comply with multiple objectives. ISO 14001 is typically implemented by a
system's management staff, possibly with the aid of consultants.
Simultaneous Compliance Guidance Manual E-5 March 2007
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Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance
For more information on ISO 14001 please see:
American National Standards Institute (ANSI) Website. http://web.ansi.org /
Global Environment & Technology Foundation. Implementing Environmental Management Systems
(EMS) in Public Entities, http://www.setf.ors/proiects/muni.cfin
Global Environment & Technology Foundation. 2002. Final Report: Second EMS Initiative for
Government Entities (2000-2002). Annandale: GETF.
Global Environment & Technology Foundation. 2000. Final Report: The EPA Environmental
Management System Pilot Program for Local Government. Annandale: GETF.
Grant, G., B.Sc., CEA, EMS(LA), CEAS. 2004. ISO 14001 and Drinking Water Quality.
Environmental Science and Engineering. January, 2004. http://www.esemas.com/0104/xcs.html
International Organization for Standardization. http://www. iso. org
ISO 1400 Information Center. http://www. iso 14000. com/
NSF International. 1996. NSF International Environmental Management System Demonstration
Project - Final Report.
Pennsylvania's Multi State Working Group Pilot. 1999. The Effects of ISO 14001 Environmental
Management Systems on the Environmental and Economic Performance of Organizations. March 27,
1999. http://www.dep.state.pa.us/dep/deputate/pollprev/Tech_Assistance/mswgreportl.htm
Redaud, J.L. 2005. ISO/TC 224 "Service Activities Relating to Drinking Water Supply Systems and
Wastewater Systems - Quality Criteria of the Service and Performance Indicators". ISO. March 31,
2005. http://www.pacinst.ors/inni/WATER/ISOTC224Description.pdf
Roig, R. and A. Saponara. 2003. ISO 14001 Environmental Management Systems: A Complete
Implementation Guide. ISO. Available for purchase from: http://www.stpub.com/pubs/allpubs.htm
USEPA Web site. Voluntary Environmental Management Systems/ISO 14001.
http://www.epa.sov/owm/isol4001/
USEPA Mid-Atlantic Region Web site. http://www. epa. gov/region3/ems/emslinks. htm
Additional Resources
AWWA. 1999d. Design and Construction of Small Water Systems. 2nd Edition. 228 pp. Denver:
AWWA.
Logsdon, G.S., A.F. Hess, MJ. Chipps, and AJ. Rachwal. 2002. Filter Maintenance and
Operations Guidance Manual. AwwaRF Report 90908. Project #2511. Denver: AwwaRF.
Simultaneous Compliance Guidance Manual E-6 March 2007
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Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance
Lauer, B. 2001. Self-Assessment for Treatment Plant Optimization, International Edition.
AWWA Publication. 256 pp. Denver: AWWA.
Renner, R.C. and B.A. Hegg. 1997. Self-Assessment Guide for Surface Water Treatment Plant
Optimization. AwwaRF Report 90736. Project #274. Denver: AwwaRF.
Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver:
AWWA.
Westerhoff, G.P., D. Gale, P.O. Reiter, S.A. Haskins, J.B. Gilbert, and J.B. Mannion. 1998a. The
Changing Water Utility: Creative Approaches to Effectiveness and Efficiency. Denver: AWWA.
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Appendix F
Considerations for Systems Complying with the Ground Water Rule
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Appendix F. Considerations for Systems Complying with the Ground Water Rule
Appendix F
Considerations for Systems Complying with the Ground Water Rule
Ground water systems will likely face challenges similar to those faced by surface water
systems when making treatment or operational changes to comply with the Stage 2 DBPR.
Unique challenges, however, may emerge when systems make treatment or source changes to
comply with the Ground Water Rule (GWR), particularly when adding a disinfectant for the first
time. This appendix focuses on these unique challenges for systems complying with the GWR,
referring to the main body of this guidance manual for additional information as appropriate.
This appendix begins with a brief overview of the GWR, focusing on the provisions that
involve a decision to add or change treatment, or to change to an alternate source of water. This
overview is followed by a discussion of corrective actions that could potentially create
simultaneous compliance issues, followed by more detailed discussion of the issues for each type
of corrective action. A list of references where the reader can find additional information is
presented at the end of this appendix and in Chapter 7 of this manual.
Additional guidance on complying with the GWR will be included in the following EPA
publications:
• Complying with the Ground Water Rule: Small Entity Compliance Guide
• Consecutive System Guide for the Ground Water Rule
• Ground Water rule Corrective Action Guidance Manual
• Ground Water Rule Source Water Monitoring Guidance Manual
• Ground Water Rule Source Water Assessment Guidance Manual
• Ground Water Rule Sanitary Survey Guidance Manual
• The Ground Water Rule Implementation Guidance
These guidance manuals are under development and will be posted on EPA's website
when they are complete, (http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html)
F.1 Overview of the Ground Water Rule
The GWR applies to all public water systems (PWS) serving ground water (except those
serving only ground water under the direct influence of surface water) including:
• Wholesale systems that supply ground water;
• Consecutive systems that buy ground water; and
• Mixed systems that use both surface water and ground water (except systems that
blend all of their ground water with surface water or ground water under the direct
influence of surface water prior to treatment under the Surface Water Treatment
Rules).
Simultaneous Compliance Guidance Manual F-l March 2007
For the Long Term 2 and Stage 2 DBF Rules
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Appendix F. Considerations for Systems Complying with the Ground Water Rule
The GWR uses a targeted risk-based approach for systems susceptible to fecal
contamination and employs four major components:
• Periodic sanitary surveys
• Source water monitoring
• Corrective action
• Compliance monitoring
Under the GWR, a system is required to take corrective action if it is found to have a
significant deficiency. Significant deficiencies are defined by the states, and may be found
during sanitary surveys or at another time when a regulator is visiting a system. If a system is
found to have a significant deficiency it must do at least one of the following:
• eliminate the source of contamination;
• correct the significant deficiency;
• provide an alternate source of water; and/or
• provide treatment that achieves 4-log virus inactivation or removal.
Systems that choose to provide 4-log virus inactivation or removal or that already provide
such inactivation or removal must monitor to demonstrate 4-log virus inactivation or removal.
Systems may also be required to undertake actions as a result of monitoring. Under the
GWR triggered monitoring requirements, systems that experience a positive total coliform
sample during TCR monitoring are required to monitor their source water for a fecal indicator. In
addition, states may require source water assessment monitoring on a monthly basis for a fecal
indicator. If a system detects a fecal indicator via either process, it may be required by the state
to take five additional source water samples and have them analyzed for a fecal indicator.
Alternatively, a state may require the system to take corrective action without collecting the
additional samples. If any of the five additional samples are positive for the fecal indicator, the
system must take corrective action by either eliminating the source of contamination, providing
an alternate source of water, or providing treatment that achieves 4-log virus inactivation or
removal. Systems that choose to provide 4-log virus inactivation or removal or that already
provide such inactivation or removal must monitor to demonstrate continuing 4-log virus
inactivation or removal.
F.2 Corrective Actions of the Ground Water Rule That Could Create
Simultaneous Compliance or Operational Issues
The corrective action provisions involve a decision-making process about treatment,
source water, and other actions such as eliminating the contamination source or correcting a
significant deficiency as illustrated in Exhibit F.I. The remainder of this appendix provides
information for systems that may be implementing corrective actions involving new treatment, a
treatment change, or an alternate source of water. It is these systems that are more likely to face
simultaneous compliance challenges and other operational issues as the GWR is implemented.
Simultaneous Compliance Guidance Manual F-2 March 2007
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Appendix F. Considerations for Systems Complying with the Ground Water Rule
Exhibit F.1 Decision Tree for Identifying Potential Simultaneous Compliance
Issues Associated with GWR Corrective Actions
System is required to
implement corrective
action
Does
the system eliminate
the source of
contamination or
correct the significant
deficiency?
Does the
system provide
4-log
inactivation or
removal of
viruses?
Does the
system use
membranes
alone to achieve
4-log virus
removal?
Does the system
use chemical
disinfection or UV
alone to achieve
4-log virus
inactivation?
See section F.3.1.1 for
potential simultaneous
compliance issues
es the
system use
chlorine to
achieve 4-log
virus
inactivation?
Does the
system
already
disinfect?
No change in treatment
or source water so no
expected simultaneous
compliance issues
See Section F.3.1.2for
potential simultaneous
compliance issues
The system provides an
alternate source of water,
for potential simultaneous
compliance issues see
section F.5
See Section F.4 for
potential simultaneous
compliance issues
The system uses
combination of technologies
See sections for individual
technologies
The system uses alternative
disinfectant for potential
simultaneous compliance
issues see Section:
F.3.2.1 for Ozone
F.3.2.2forUV
F.3.2.3 for Chlorine Dioxide
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F-3
March 2007
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Appendix F. Considerations for Systems Complying with the Ground Water Rule
F.3 Inactivation Using Disinfection
Inactivation through disinfection is one of several possible corrective actions that could
be implemented by ground water systems with significant deficiencies or fecal contamination.
Systems can use free chlorine or a state-approved alternative disinfection technology (40 CFR
141.403(a)(6)(iv)). The dose required will be set by the state using either existing CT tables or
state approved alternatives. Exhibit F.2 summarizes EPA's recommended CT values to achieve
4-log virus inactivation using the various chemical disinfectants. For UV, the required dose for
4.0-log inactivation of viruses is 186 millijoules per centimeter squared (mJ/cm2) (40 CFR
Exhibit F.2 CT Values for Inactivation of Viruses Using Different Disinfectants
(min*mg/L), pH range 6 - 9
Disinfectant
Chlorine
Chlorine Dioxide
Ozone
Temperature (°C)
<1
12
50.1
1.8
5
8
33.4
1.2
10
6
25.1
1.0
15
4
16.7
0.6
20
3
12.5
0.5
25
1
8.4
0.3
Source: USEPA1991
In some cases, systems will already be disinfecting but will need to increase disinfectant
dose or contact time before the first customer to provide 4-log inactivation of viruses. In other
cases, systems may be disinfecting for the first time. A ground water system that initiates
chemical disinfection will be required to meet the Stage 2 DBF Rule (and possibly the Stage 1
DBPR depending on timing). In addition, systems may face LCR or TCR challenges in balancing
disinfectant selection, CT requirements, etc. Simultaneous compliance issues specific to chlorine
and alternative disinfectants are discussed in Sections F.3.1 and F.3.2, respectively. Section
F.3.1 addresses potential issues for those systems initiating chlorine as well as those systems
increasing chlorine dose or CT.
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March 2007
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Appendix F. Considerations for Systems Complying with the Ground Water Rule
F.3.1 Chlorine
Because chlorine is not a technology that systems will use for LT2ESWTR compliance,
chlorination is not discussed separately in the main text of this Simultaneous Compliance
Guidance Manual. Instead, it is used as the baseline for comparison to other disinfection
technologies. Some ground water systems, however, will either begin chemical disinfection
using free chlorine, or will increase CT by increasing the free chlorine dose or contact time as a
corrective action for the GWR. Thus, a brief description of chlorination and an overview of its
simultaneous compliance issues are provided below.
Chlorination is the oldest disinfection process used to treat drinking water. This process
utilizes free chlorine to kill most bacteria, viruses, and other pathogens. Chlorine may be
introduced into water in the form of gas, sodium/calcium hypochlorite (tablets, solutions, or
powder), and other compounds. Free chlorine refers to the chlorine that is not combined with
ammonia or organic nitrogen in the water (i.e., elemental chlorine gas (Cb), hypochlorous acid,
and hypochlorite). A free chlorine residual may remain in the water after adequate CT has been
achieved and thus provide for residual (or secondary) disinfection throughout a water distribution
system. Residual disinfection can help control biofilm growth in the distribution system and
protect against pathogen intrusion through cross connections, infiltration, or line breaks.
A free chlorine residual impacts water chemistry in a number of ways that are important
for water treatment. It increases the oxidation-reduction potential (ORP) of the receiving water.
The consequences of this effect are system-dependent (White 1999) and subsequently may either
be advantageous or not. ORP can control the reactions on the surface of pipes, including the
formation of passivating scales. Changes in ORP can lead to alteration of these reactions and
release of metals. Lytle and Schock (2005) discovered a change in ORP could cause changes to
lead-containing scales and release of lead into the water. Chlorine addition also affects pH;
chlorine gas decreases pH while sodium or calcium hypochlorite increases pH (White 1999).
Both pH and total alkalinity of water after chlorination must therefore be taken into careful
consideration.
In general, systems using chlorine to disinfect may have to contend with the following
issues:
• Chlorinated DBF (TTHM and HAAS) formation
• Compliance with free chlorine MRDL of 4.0 mg/L (40 CFR 141.65(b)(l))
• Taste and odor concerns
• Change in pH
• Change in ORP
• Increased corrosivity towards iron and copper (Cantor et al. 2003)
F.3.1.1 Initiating Chlorination
The initiation of disinfection using free chlorine can alter the water chemistry entering
the distribution system. All of the simultaneous compliance considerations described in section
3.1 of this appendix apply to most surface water, ground water, and blended water sources.
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Appendix F. Considerations for Systems Complying with the Ground Water Rule
However, there are some special considerations with regard to initiating disinfection or
increasing disinfectant dose when using free chlorine for ground water systems.
Ground water sources are often anoxic, or contain very low levels of dissolved oxygen.
Addition of free chlorine can cause a significant increase in the redox potential of the water,
which in turn can cause precipitation of dissolved constituents in the source water, and/or
oxidation and precipitation of dissolved constituents in corrosion scales. Precipitation can lead
to discolored water reaching the customer's tap.
Introduction of a disinfectant residual into the distribution system and the subsequent
destabilization of corrosion scales can result in sloughing of established biofilms. Release of
biofilm organisms could impact TCR compliance. Over the long term, however, a disinfectant
residual is expected to achieve better control over microbial growth (USEPA 2002e) and
improve TCR compliance.
The form of free chlorine used for treatment can impact the pH of the finished water,
depending on the buffering capacity. The use of chlorine gas (hypochlorous acid) can lower the
pH and the use of sodium hypochlorite can increase the pH. Generally, ground water supplies
have greater buffering capacity compared to surface water supplies. Thus, pH impacts may be
less for ground water systems. Potential simultaneous compliance issues associated with
decreasing pH are discussed in Section 3.4 of the main text of this guidance manual. Increasing
the pH in ground water systems may enhance precipitation of dissolved metals such as iron and
manganese. Increasing the pH may also decrease the adsorptive capacity of iron scales for
arsenic, resulting in increased arsenic levels at the tap.
For ground water systems with low dissolved oxygen (DO), adding chlorine has a similar
effect on copper corrosion as increasing DO. Consequently ground water systems that
implement disinfection with chlorine may experience increased copper corrosion and LCR
compliance challenges. High alkalinity/dissolved inorganic carbon (DIC) ground water systems
are also susceptible to increased copper corrosion which may be exacerbated when a chlorine
residual is present (USEPA 2003h; Schock and Fox 2001).
If organic material is present in the groundwater, adding a disinfectant can form DBFs. If
the organic concentration is high enough there could be problems complying with the Stage 2
DBPR (or Stage 1 DBPR depending on the timing). Systems with high organic carbon
concentrations in their groundwater may need to consider an alternative disinfectant or remove
the organic carbon to keep DBF levels under the Stage 2 DBPR MCL.
F.3.1.2 Increasing Chlorine Dose or Contact Time
Increasing the chlorine dose can also increase the redox potential of water, which can
cause precipitation of dissolved constituents in the distribution system, and/or oxidation and
precipitation of dissolved constituents in corrosion scales. Increasing the chlorine dose or contact
time to achieve CT would most likely have less of this effect than when a system adds
disinfection for the first time.
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Appendix F. Considerations for Systems Complying with the Ground Water Rule
If a ground water source contains organic material, TTHM and HAAS levels may
increase when the chlorine dose is increased, potentially causing problems with compliance with
the Stage 2 DBPR (or the Stage 1 DBPR depending on timing). Increasing chlorine contact time
prior to the first customer may be a lesser impact on TTHM and HAAS formation than
increasing chlorine dose.
F.3.2 Alternative Disinfectants
Chapter 5 of this manual presents simultaneous compliance and operational issues
associated with initiation of chlorine dioxide, ozone, and UV for both surface and ground water
systems. Some additional considerations for ground water systems are provided below.
F.3.2.1 Ozone
Some ground water systems may face challenges in meeting the bromate MCL. As
discussed in Section 5.2 of this manual, ozone can react with bromide in the source water to form
bromate, which has an MCL of 10 ppb under the Stage 1 D/DBPR. Ground water sources
generally have higher levels of bromide than surface waters (USEPA 1999J). Consequently
ground water systems may face more difficulty in complying with the bromate MCL under the
Stage 1 and Stage 2 D/DBPR.
Ground water sources are often anoxic, or contain very low levels of dissolved oxygen.
Addition of ozone can cause a significant increase in the redox potential of the water, which in
turn can cause precipitation of dissolved constituents in the source water, and/or oxidation and
precipitation of dissolved constituents in corrosion scales. Precipitation can lead to discolored
water reaching the customer's tap.
Ozonation is a more complex treatment process (compared to liquid feed systems such as
hypochlorite) which may pose implementation challenges for ground water systems with
multiple wells.
Ozonation increases AOC levels. AOC acts as a food source for microbes and can lead
to increased microbial growth within the distribution system and potential simultaneous
compliance issues with the TCR, especially for ground water systems that do not provide a
disinfectant residual. EPA recommends that systems consider AOC reduction through use of
biological filtration prior to water entering the distribution system.
F.3.2.2 UV Disinfection
Simultaneous compliance issues associated with adding UV disinfection are discussed in
Section 5.3 of this guidance manual. This section presents special considerations for ground
water systems adding UV to achieve 4-log virus inactivation for the GWR.
As noted in Section 5.3, the UV dose needed for 4-log inactivation of viruses is very
high. At present, EPA is unaware of available challenge testing procedures that can be used to
validate the performance of UV reactors at dose levels needed for this level of virus inactivation.
Simultaneous Compliance Guidance Manual F-7 March 2007
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Appendix F. Considerations for Systems Complying with the Ground Water Rule
EPA recommends, therefore, that UV technology be used in a series configuration or in
combination with other technologies to provide a total 4-log treatment of viruses to meet the
GWR's requirements.
Dissolved minerals such as iron, manganese, and calcium can impact the disinfection
effectiveness of UV and cause fouling of the UV lamp sleeves. Because ground waters typically
have higher dissolved mineral content, systems using ground water may face these problems
more frequently than surface water systems.
When UV disinfection is applied to water with a free or total chlorine residual, some
reduction of the residual may occur. The reduction in free chlorine residual is proportional to the
delivered dose and independent of flow rate (Brodkorb and Richards 2004; USEPA 2006b). The
reduction in total chlorine residual is also proportional to the delivered dose (Wilczak and Lai
2006). Ground water systems that already provide a disinfectant residual will need to consider
the appropriate placement of the UV disinfection system.
UV systems tend to be more sensitive to power quality than pumping equipment. It is
possible that the UV system lamps could lose arc, but the pumping system is unaffected, and
then untreated or inadequately treated water can pass through the system. This could be a
concern for ground water systems that do not provide residual disinfection. Additionally,
because ground water systems typically involve pumping, there may be issues with hydraulic
surge and negative pressures. Careful design and operation are important to address these issues.
F.3.2.3 Chlorine Dioxide
Chlorine dioxide dose is limited both by the MRDL of 0.8 mg/L, and the chlorite MCL of
1.0 mg/L under the Stage 1 DBPR. The dose restrictions and relatively high CT for chlorine
dioxide, compared to chlorine, under cold water conditions may mean additional new
infrastructure such as a clearwell is necessary for ground water systems to allow sufficient
contact time to meet 4-log virus inactivation requirements.
As discussed in Section 5.4 of this manual, systems using chlorine dioxide must monitor
daily at entry points to the distribution system. Some ground water systems may have multiple
entry points thereby increasing overall monitoring requirements, which may be especially
challenging for small ground water systems.
Also as discussed in Section 5.4, chlorine dioxide is a strong oxidant and can oxidize
iron, arsenic, and other inorganics present in source water, causing precipitants to form. Ground
water sources can have higher levels of these and other inorganic constituents compared to
surface water systems.
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Appendix F. Considerations for Systems Complying with the Ground Water Rule
F.4 Membrane Processes
Simultaneous compliance issues and operational concerns associated with using
membranes to treat surface water and ground water are described in detail in Sections 4.2 and 4.3
of this guidance manual. Specific considerations when using membrane processes for virus
removal from groundwater are described here. Items of interest stem primarily from the removal
of constituents from the feed water and are thus highly dependent on the properties of the
membrane(s) used and should be considered accordingly.
Membrane systems generally require some form of pretreatment to minimize fouling and
reduce the number of cleaning periods required. Typically some form of media filtration
precedes a membrane process, particularly for NF and RO membranes. The type of pretreatment
process used is primarily dictated by the groundwater chemistry, specifically regarding hardness,
iron, manganese, calcium, magnesium, sulfate, and silica.
Anoxic groundwater sources that become exposed to the atmosphere during pumping or
aeration may result in the mineral precipitation and membrane scaling. Systems that aerate the
groundwater to oxidize the iron, manganese, or other compounds must remove the precipitated
minerals before they reach the membrane unit to reduce fouling and scaling.
Reductions in pH, hardness, alkalinity, and other minerals may upset the distribution
system chemical equilibrium, causing corrosion and/or scale destabilization. This may lead to
compliance issues with the LCR. Post-treatment of membrane product waters may be required
for those treated using NF and RO membranes to reduce the corrosivity of the water.
Before installing membranes, ground water systems should be sure to factor in increased
capital and O&M costs associated with pre- and post-treatment requirements, especially for
ground water systems with multiple wells.
F.5 Selection of an Alternative Source
A ground water system may decide to provide an alternate source of water as a corrective
action under the GWR. Selecting an alternative source may be more technically and
economically feasible than other corrective actions using the existing source.
Ground water systems considering an alternate source as their corrective action for the
GWR will face similar challenges to systems that select an alternate source to comply with the
Stage 2 DBPR or LT2ESWTR. These issues are discussed in section 3.1 of this guidance
manual and summarized below.
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Appendix F. Considerations for Systems Complying with the Ground Water Rule
• Blending of different waters when only one of multiple sources is replaced;
• Changes in water quality parameters (WQPs) such as DO, temperature, pH,
alkalinity/DIC, redox potential, turbidity, NOM/TOC, dissolved iron and manganese,
and the presence of other contaminants and need for additional treatment;
• Impact of the change in WQP on corrosion control for LCR compliance, DBF
formation (if already disinfecting), or AOC levels that might impact TCR
compliance;
• Introduction of new contaminants or higher concentrations of existing contaminants
(e.g., iron, manganese, hydrogen sulfide);
• A change in raw water pH that could adversely affect water treatment and compliance
with the LCR;
• For GWR systems that are already disinfecting, an alternate source water under
reduced conditions (e.g., little or no dissolved oxygen) may exert increased
disinfectant demand; and
• Changes in aesthetic quality may generate customer complaints.
References
AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper
Rule Corrosion Control Treatment. Denver: AWWA.
Brodkorb, T. and D. Richards. 2004. UV disinfection design to avoid chlorine destruction
in high UVT waters. Presented at Ontario Water Works Association. Niagara Falls,
Ontario, Canada. May, 2004.
Cantor, A., J.K. Park, and P. Vaiyavatjamai. 2003. Effect of Chlorine on Corrosion in
Drinking Water Systems. Journal of American Wwater Works Association. 95(5): 112-
123.
Schock, M.R. and J.C. Fox. 2001. Solving Copper Corrosion Problems while Maintaining
Lead Control in a High Alkalinity Water using Orthophosphate. Presented at the Ohio
AWWA Annual Conference. August 30, 2001. Cleveland: AWWA.
U.S. EPA. 1991. Guidance Manual for Compliance with the Filtration and Disinfection
Requirements for Public Water Systems Using Surface Water Sources. Developed by
Malcolm Pirnie and HDR. 568 pp. Washington D.C.: USEPA.
Simultaneous Compliance Guidance Manual F-10 March 2007
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Appendix F. Considerations for Systems Complying with the Ground Water Rule
USEPA. 1999J. M/DBP Stage 2 Federal Advisory Committee (FACA2) Distribution
Systems & ICR Data Analysis (12 months).
http://www.epa. gov/safewater/mdbp/st2oct99 .html
USEPA. 2002e. Health Risks from Microbial Growth and Biofilms in Drinking Water
Distribution Systems. Office of Ground Water and Drinking Water.
USEPA. 2003h. Revised Guidance Manual for Selecting Lead and Copper Control
Strategies. Office of Water. EPA 816-R-03-001. March, 2003.
USEPA. 2006b. Ultraviolet Disinfection Guidance Manual for the Final Long Term 2
Enhanced Surface Water Treatment Rule. Office of Water. EPA 815-R-06-007.
November, 2006.
http://www.epa. gov/safewater/disinfection/lt2/pdfs/guide_lt2_uvguidance.pdf
White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition.
New York: Van Nostrand Reinhold Co.
Wilczak, A. and H. Lai. 2006. Preliminary bench and pilot evaluation of UV-irradiation
for nitrification control. In Proceedings of the American Water Works Association Annual
Conference. June 11-16. San Antonio: AWWA.
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Appendix F. Considerations for Systems Complying with the Ground Water Rule
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