SEPA
Stage 2 Disinfectants and Disinfection
Byproducts Rule (DBPR) and Consecutive
System In-Depth Analysis
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US EPA | Office of Water (4606M)
EPA 815-R-19-001
July 2019
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Acknowledgements
The Stage 2 Disinfectants and Disinfection Byproducts Rule (DBPR)
and Consecutive System In-depth Analysis has been a collaborative
effort between the EPA and state primacy agencies. The following
were key contributors to the development of this document.
¦ Mary Hollingsworth, Matt Prater, Stacy Jones,
and Peter Poon, Indiana Department of
Environmental Management
¦ Peter Coodmann, Kellee Husband, and Joe
Uliasz, Kentucky Department of Environmental
Protection
¦ Patricia Gardner, Felicia Fieo, Yoshi Nakajima,
and Syed Imteaz, New Jersey Department of
Environmental Protection
¦ Greg Wavra and Tammy Lamphear, North
Dakota Department of Health
¦ Lisa Daniels, Dawn Hissner, Jason Minnich,
and Jeff Allgyer, Pennsylvania Department of
Environmental Protection
¦ Alan Roberson and Darrell Osterhoudt,
Association of State Drinking Water
Administrators
3
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Contents
CHAPTER 1: Stage 2 DBPR and Consecutive CWS Challenges 6
CHAPTER 2: National Data Analysis of Stage 2 DBPR Compliance 10
CHAPTER 3: Challenges, Lessons Learned, and Best Practices 18
CHAPTER 4: Approaches to Reduce DBPs through Optimization 27
Additional Resources and References 33
Acronyms 35
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Executive Summary
The goal of an In-Depth Analysis is to identify compliance challenges related to a specific regulatory requirement
and to share best practices for enhancing implementation. This national effort is strategic in scope, is conducted
as a joint effort between the U.S. Environmental Protection Agency (EPA) and the states, and supports the EPA's
breakthrough measure to reduce the number of community water systems (CWSs) with health-based violations
by 25 percent within five years.
The EPA collaborated with the states to select areas
for analysis, and state volunteers to participate in the
effort. The EPA and the states work together to a)
understand the root cause of the implementation
issue; b) seek state best practices; and c) develop and
provide targeted training and technical assistance to
enhance the effectiveness of the Safe Drinking Water
Act (SDWA) program.
The National Primary Drinking Water Regulation
(NPDWR) with the largest number of CWSs in violation,
roughly 30 percent of all violations during fiscal
year 2017 and 2018, was the Stage 2 Disinfectants
and Disinfection Byproduct Rule (DBPR). The first
chapter of this report discusses the Stage 2 DBPR and
Consecutive CWS Challenges. During this effort the
EPA learned that more than half of the CWSs with a
Stage 2 DBPR violation were consecutive systems, with
a violation rate of 4.9 percent for consecutive CWSs
compared to 1.4 percent for non-consecutive.
The second chapter discusses the national data
analysis that was done to identify areas of the U.S. with
Stage 2 DBPR compliance challenges and evaluate
common characteristics of the CWSs that were out of
compliance. As part of this analysis, the EPA looked at
geographic distribution of Stage 2 DBPR health-based
violation and found that these systems are located in
a band from the mid-Atlantic states down through
Texas, along with Alaska and Puerto Rico. The EPA
also analyzed the maximum contaminant level (MCL)
violations and found that:
¦ Total trihalomethanes (TTHM) MCL violations
[systems with only TTHM or those with both TTHM
and haloacetic acids (five) (HAA5)] were dominant
comprising approximately 80 percent of the
systems in violations;
¦ More than 70 percent of the violations occur at
surface water systems; and
¦ Stage 2 DBPR violations occurred more frequently,
and at higher concentrations above the MCL, for
those systems serving 501 to 10,000 persons.
State best practices are provided in the third chapter.
This information was based on site visits to the five
partner states, as well as feedback from 32 other
states provided by Association of State Drinking Water
Administrators (ASDWA). The chapter is organized
around the following key implementation challenges;
1. What approaches can a CWS take to reduce
disinfection byproduct (DBP) formation?
2. What are the best practices for distribution system
sampling and analytical methods?
3. What approaches can be used to facilitate
coordination between a wholesale and
consecutive system?
4. What capacity development tools can be used to
address DBP issues?
5. How can Drinking Water State Revolving Fund
(DWSRF) resources be used to assist systems with
DBP violations?
6. How can state enforcement be used to help
systems return to compliance?
7. What approaches can be used to enhance
operator training on DBP compliance issues?
The last chapter provides approaches to reduce DBPs
through optimization. This general approach was
developed through pilot projects and field studies
carried out by the EPA's Area Wide Optimization
Program (AWOP).
The information provided in this report is intended
to help state primacy agencies understand and
address the compliance challenges related to the
Stage 2 DBPR and consecutive systems, however
it is important to recognize the limitation of the
information provided in this report. The national data
analysis presented in Chapter 2 represents a snapshot
in time. The state implementation challenges and
lessons learned provided in Chapter 3 may not be
inclusive of all issues and approaches related to Stage 2
DBPR and consecutive systems. And finally, the system
optimization approach provided in Chapter 4 shows
one approach developed by EPA's AWOP program,
however other approaches may also be effective.
5
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Chapter 1: Stage 2 DBPR and Consecutive
CWS Challenges
Why conduct a SDWA subject specific In-Depth Analysis?
A subject-specific In-Depth Analysis seeks to identify opportunities to improve the effectiveness of
National Primary Drinking Water Regulation (NPDWR) implementation. This joint effort is conducted
on a voluntary basis between the U.S. Environmental Protection Agency (EPA) and primacy
agencies1. With the understanding developed through this effort, the EPA will work with
states to develop and provide targeted training and technical assistance to enhance the
effectiveness of the Safe Drinking Water Act (SDWA) programs.
/# EPA M
f Goal: 1
decrease
health based
violations by 25%
by 2022
"These violations are
not shown to scale
This effort supports the EPA's
breakthrough measure
to reduce the number of
ommunity water systems
(CWSs) with health-based
violations by 25 percent
by 2022. Health-based
violations include
violations of maximum
contaminant levels
r(MCLs), maximum
residual disinfectant levels
(MRDLs), and treatment
technique (TT) rules.
Why focus on Stage 2 DBPR?
While health-based violations occur all over the
U.S., in recent years the Stage 2 Disinfectant and
Disinfection Byproduct Rule (DBPR) consistently
makes up a substantial portion of the health-based
violations (Figure 1). In fiscal year (FY) 2017,1,188 of
the approximately 50,000 CWSs in the U.S., had a
Stage 2 DBPR health-based violation, comprising
nearly 34 percent of all CWSs in violation. As Figure 2
shows, Stage 2 DBPR health-based violations were
not only the most common violation in terms of
both number of violations and CWSs in violation,
they also impacted the second largest number of
people. Furthermore, while the geographic distribution
of all health-based violations (Figure 3a) illustrates a
general distribution throughout the U.S., the CWSs
with Stage 2 DBPR health-based violations (Figure
3b) are localized in specific regions; more details will
be discussed in Chapter 2 For these reasons, the goal
of this In-Depth Analysis is to understand the Stage 2
DBPR implementation challenges and share state best
practices to improve compliance.
RTCR
LCR
5nH^
LT2ESWTR
MCL
MRDL
i
IOC
GWR
N03
RTCR
MRDL
Rads
MCL
Figure 1: Proportions of CWSs with health-based violations
in FY17 by rule. Some CWSs violated more than one rule
and are therefore counted more than once.
For the purpose of this report, primacy agencies are referred to as states.
Stage 2 DBPR and Consecutive System In-Depth Analysis
6
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 1
10,000,000,000
9,000,000,000
8,000,000,000
E 7,000,000,000
o
"cs
O 6,000,000,000
>
¦™ 5,000,000,000
o
J2 4,000,000,000
3
Q.
o
3,000,000,000
2,000,000,000
1,000,000,000
Stage 2 DBPR
(34% of CWSs
with violations)
1,500 2,000 2,500 3,000 3,500
Total Number of Health-Based Violations
Figure 2: Most common
health-based violations at
CWSs in FY17, plotting each
rule by the population in
violation versus the total
number of violations for that
rule, with the size of the circle
representing the number of
systems in violation. MCL
violations are shown in green
and TT violations are shown
in yellow. As illustrated, Stage
2 DBPR has the largest total
number of violations, the
most CWSs in violation and
the second largest population
in violation.
&'• •: nh 'V. • w'.-iW:".
v. • • • .> ;.v .-:\-
OH
• Community Water Systems
Relative Density of Systems
Low High
Density Density
• w ¦ i
' J"" V-"'..
v •;
Guam (0)
American Samoa (1)
Northern Mariana Islands (0)
Figure 3: Distribution of health-based violations at CWSs in FY17. Maps show a) locations of all CWSs with health-
based violations, and b) locations of CWSs with Stage 2 DBPR health-based violations.
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 1
What are DBPs and how do they form?
Disinfection byproducts (DBPs) are formed when
disinfectants used in water treatment react with natural
organic matter (i.e., decaying vegetation) present in the
source water or distribution system. DBP formation is
influenced by several factors including:
¦ disinfectant type and dose,
¦ inorganic and organic precursor concentrations,
¦ pH,
¦ temperature, and
¦ water age.
The EPA has established NPDWRs in the Stage 1 DBPR
and the Stage 2 DPBR for the following DBPs: total trihalo-
methanes (TTHM), haloacetic acids (five) (HAA5), bromate,
and chlorite. Stage 1 DBPR also included a TT requirement
for precursor removal (e.g., natural organic matter).
Why focus on consecutive CWS violations?
The EPA defines a consecutive CWS as a public water
system (PWS) that receives some or all of its finished water
from one or more wholesale systems.2 The EPA recognizes
that individual states may have a different definition for a
consecutive CWS.
FY17 Data
Consecutive
13,457
Total
Non-Consecutive
968
CWSs
50.259
Systems
in Violation
3.508
7.2%
663
Violation Rate
7.0%
overall
Systems
with Stage 2
DBPR violations
1,188
Violation Rate
4.9%
2.4%
Stage 2 DBPR
36,802
2,540
525
6.9%
1.4%
Figure 4: Proportions of CWSs with health-based
violations in 2017 by rule. Some CWSs violated
more than one rule and are therefore counted
more than once.
The Stage 2 DBPR can be challenging for consecutive
CWSs to implement, as they have little control over the
treatment processes of the water they receive, yet they
must comply with MCLs for TTHM and HAA5. Further, the
purchased finished water that a consecutive CWS receives
may contain high levels of DBP precursors, or even high
levels of DBPs. As such, water may meet the MCLs at the
system interconnection, but concentrations may continue
to increase in the consecutive systems distribution network.
According to data pulled from the Safe
Drinking Water Information System
(SDWIS) Federal Reporting Service, nearly
27 percent of CWSs in the U.S. are at least
partially consecutive (Figure 4). When all
health-based rule violations are considered,
the violation rates for non-consecutive
and consecutive are similar. In contrast,
consecutive CWSs account for 56 percent of health-based Stage 2 DBPR violations that occurred in FY17.
The Stage 2 DBPR health-based violation rate for consecutive community water systems is 3.5 times that
observed for non-consecutive CWSs, 1.4 percent for non-consecutive compared to 4.9 percent for consecutive
CWSs. As such, this In-Depth Analysis is further concentrating on Stage 2 DBPR violations at consecutive CWSs.
The Stage 2 DBPR violation rate for
consecutive CWSs is 3.5 times greater
than non-consecutive CWSs.
2 See 40 CFR 141.2
8
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 1
Seeking State Partners
At the March 2018 ASDVVA Member Meeting,
the EPA made a request for state partners to
voluntarily participate in this In-Depth Analysis.
Five states agreed to work with the EPA including:
Indiana, Kentucky, New Jersey, North Dakota, and
Pennsylvania. During the In-Depth Analysis, the EPA
conducted a national data analysis of Stage 2 DBPR
health-based violations (Chapter 2), conducted state
site visits to evaluate compliance challenges and
share lessons learned and best practices (Chapter
3), and worked with the Area Wide Optimization
Program (AWOP) to identify strategies for Stage 2
DBPR compliance (Chapter 4).
The information provided in this report is intended
to help state primacy agencies understand and
address the compliance challenges related to the
Stage 2 DBPR and consecutive systems, however it
is important to recognize the limitation of the
information provided in this report. The national
data analysis presented in Chapter 2 represents
a snapshot in time. The state implementation
challenges and lessons learned provided in Chapter
3 may not be inclusive of all issues and approaches
related to Stage 2 DBPR and consecutive systems.
And finally, the system optimization approach
provided in Chapter 4 shows one approach
developed by EPA's AWOP program, however other
approaches may also be effective.
What has been done previously
on the issue?
The EPA has recognized the challenges related
to Stage 2 DBPR compliance for consecutive CWSs
since the rule was promulgated in 2006. The
EPA has several guidance documents available
to promote compliance with the Stage 2 DBPR
requirements. Refer to the Additional Resources
and References section for a list of publications at
the end of this document.
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Chapter 2: National Data Analysis of
Stage 2 DBPR Compliance
What can we learn with SDWIS?
SDWIS contains information about PWSs and their violations of federal drinking water regulations, as
reported to the EPA by the states. SDWIS is a valuable resource for answering the following questions
related to Stage 2 DBPR and consecutive CWS challenges:
¦ How have Stage 2 DBPR violations changed over time?
¦ Are there geographic areas where Stage 2 DBPR MCL violations are more common? Is this pattern
similar for consecutive CWS?
¦ How does source water type affect Stage 2 DBPR compliance?
¦ Are there noteworthy distinctions between HAA5 and TTHM violations?
¦ Which system sizes have the most Stage 2 DBPR MCL violations?
The SDWIS data from FY17 (October 2016 through September 2017) were used for this In-Depth Analysis
because FY17 data were the most recent data available at the beginning of this project. A recent review
of FY18 data shows a similar pattern to the FY17 data.
How have Stage 2 DBPR violations changed over time?
The Stage 2 DBPR monitoring and compliance requirements were phased in over several years as the
rule took effect. As Figure 5 shows, the number of systems with Stage 2 DBPR health-based violations
increased substantially from 2013 to 2016, as the Stage 2 DBPR requirements came to apply to all
categories of CWSs.
To have a Stage 2 DBPR health-based violation (i.e., a TTHM or HAA5 MCL violation), a full year of
monitoring is required; the previous four quarters for each sampling location are considered when
calculating compliance. For example, the value for the fourth quarter (Q4) of FY15 includes sample
results from the period from FY15 Q1 to FY15 Q4. Figure 5 indicates that the number of systems with
Stage 2 DBPR health-based violations was highest in 2016 and has subsequently slowly decreased.
Stage 2 DBPR and Consecutive System In-Depth Analysis
10
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 2
All CWSs had to comply by October 1, 2014
1,400
Schedule 2
CWSs had
1 200 *° comP'y by
October 1,
2012
Schedule 3 arid most
Schedule 4 CWSs had
to comply by October 1,
2013
Schedule 4 CWSs conducting
Cryptosporidium monitoring had
to comply by October 1 , 2014
c
o
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eg
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£
>
CO
0)
.Q
E
3
800
600
400
200
2013 2013 2013 2014 2014 2014 2014 2015 2015 2015 2015 2016 2016 2016 2016 2017 2017 2017 2017 2018 2018 2018
Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3
Submission Year Quarter
Figure 5: Number of CWSs with Stage 2 DBPR health-based violations from 2013 to 2018, The results for each calendar
quarter represent the number of Stage 2 DBPR health-based violations that occurred during the previous year.
Are there geographic areas where Stage 2 DBPR MCL violations
are more common?
Figure 6a shows how the number of CWSs in each state varies across the country. For example, Texas has
4,652 CWSs whereas Hawaii only has 116 CWSs. Figure 6b shows the number of CWS with Stage 2 DBPR
health-based violations. Because of the variation in numbers of CWSs among states, it is helpful to normalize
the occurrence of Stage 2 DBPR health-based violations by reporting them as percentages of CWSs (see
Figure 6c) to identify more accurately the states that are challenged with Stage 2 DBPR compliance.
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 2
As Figure 6 shows, rates of Stage 2 DBPR health-based violations are not uniform across the states.
Higher violation rates form a belt from the states of the south-central U.S. to the mid-Atlantic, with
Oklahoma, Kentucky, and Louisiana having the highest violation rates. High violation rates were also
found in Alaska and Puerto Rico.
Number of
Community
Water Systems
Number of CWSs
with Stage 2 DBPR
HB Violations
Percent CWSs
with Stage 2
DBPR HB Viol
Figure 6: Distribution of CWSs and Stage 2 DBPR health-based violations across the U.S. in FY17. Maps represent a)
number of CWSs in each state; b) number of CWSs with Stage 2 DBPR health-based violations in each state; and c)
percent of CWSs with Stage 2 DBPR health-based violations in each state. In addition to the violations represented
there were three violations in the Navajo Nation, one violation in American Samoa, and four violations for CWSs in the
EPA direct implementation program.
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 2
Are there geographic areas where consecutive CWSs Stage 2 DBPR MCL
violations are more common?
Just as the number of all CWSs varies from state to state, so does the number of consecutive CWSs. Figure 7a
shows for example, that Texas has 1,891 consecutive CWSs while Idaho only has 15. Figure 7b illustrates how
the percentage of CWSs that are consecutive CWSs also varies. For example, over 70 percent of Kentucky's
systems are consecutive CWSs, but only 2 percent of Idaho's systems are consecutive CWSs. Figure 7c shows
the number of consecutive CWSs with Stage 2 DBPR health-based violations, and Figure 7d shows the
percentage of consecutive CWSs with a Stage 2 DBPR health based violation. Although the rate of Stage 2
DBPR health-based violations is higher at consecutive CWSs than at all CWSs, the geographical distribution
of violations is similar. Some states with larger proportions of consecutive CWSs, such as Oklahoma and
Kentucky, are states where the highest rates of Stage 2 DBPR health-based violations occurred.
Percent CWSs
that are Consec
Systems
| 0.0-2.0%
b
B 2 01 ~ 12-6%
B 12.7-21.1%
^ 21.2-34.8%
B 34 9 " 511%
^51.2-72.8%
24.5% 30.2%
>/o 24.2%
Number of
Consecutive
Systems
01"/° 29.5%
0-50
I 51 - 129
130-264
265-445
446 - 820
821 - 189}
Percent of
Consecutive
Systems with
Stage 2 DBPR
HB Viol
Number of
Consecutive
Systems with
Stage 2 DBPR
HB Viol
o%
Figure 7: Distribution of consecutive CWSs and Stage 2 DBPR health-based violations across the U.S. in FY17. Maps
represent a) number of consecutive CWSs in each state; b) percent of CWSs that are consecutive CWSs in each
state; c) number of consecutive CWSs with Stage 2 DBPR health-based violations in each state; and d) percent of
consecutive CWSs with Stage 2 DBPR health-based violations in each state. In addition to the violations represented,
there was one violation each in the Navajo Nation and the EPA direct implementation program.
13
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 2
As shown in Chapter 1, the overall Stage 2 DBPR violation rate for non-consecutive CWSs is 1.4 percent,
while the rate for consecutive CWSs is 4.9 percent. A common set of issues may be causing Stage 2
DBPR violations at all CWSs that is exacerbated for consecutive CWSs, including longer disinfected
water residence times and the limited ability to control treatment processes that are managed by the
wholesaler.
How does source water affect Stage 2
DBPR MCL compliance?
PWSs use one or more of three categories
of source water: surface water, ground
water under the direct influence of
surface water, and ground water.
Based on SDWIS data, Stage 2
DBPR health-based violations
occur primarily at CWSs that
use surface water as the
source water type (Figure
8). Overall, 70 percent of the
violations occur at CWSs using
surface water, regardless of
producing their own water or
purchasing from another system.
However, a substantial number
of violations, occur at CWSs using
ground water, as well. This relationship is
more pronounced when you look at only
consecutive systems where approximately
81 percent had a surface water primar
source, compared to approximately 18
percent for ground water. Violations for non-
consecutive systems were approximately 62
percent surface water, whereas 37 percent of
violations were for ground water sources.
Surface water
purchased
Unknown Primary Source
Ground water
Ground water purchased
Purchased ground water under
influence orsurface water
Surface water
Groundwater under influence
of surface water
Figure 8: Stage 2 DBPR health-based violations based on primary
source water type used (FY17). Over 70 percent of the CWSs with
Stage 2 DBPR health-based violations use surface water sources.
14
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 2
| HAA5 only
HAA5 and TTHM
TTHM only
¦Q
3 747 447 300
2 62.9% 67.4% 57.1%
All Consecutive Non-Consecutive
Systems Systems
Figure 9: Frequency of Stage 2 DBPR MCL violation types at consecutive and non-consecutive CWSs (FY17). TTHM
MCL violations (TTHM and TTHM/HAA5 MCL violations added together) account for more than 80 percent of the systems
with Stage 2 DBPR health-based violations. This pattern is true for both consecutive and non-consecutive systems.
Are there distinctions between HAA5 and TTHM violations?
PWSs with Stage 2 DBPR health-based violations can have one of three types of violations: TTHM MCL
violations, HAA5 MCL violations, or both TTHM and HAA5 MCL violations (TTHM/HAA5 MCL violations).
When MCL violations are grouped into these three categories (Figure 9) it shows that TTHM MCL violations
(systems with either a TTHM or TTHM/HAA5 MCL violations added together) account for more than 80
percent of the systems with Stage 2 DBPR health-based violations. This pattern is slightly more pronounced
at consecutive (83 percent) than in non-consecutive CWS (76 percent). In contrast, systems with HAA5
MCL violations were overall much lower proportion of systems in violation than for TTHM (37 percent), with
violations higher at non-consecutive CWSs (43 percent) than at consecutive CWSs (33 percent).
Which system sizes have the most Stage 2 DBPR health-based violations?
CWSs serving 501-3,300 people represent the system size category with the most Stage 2 DBPR
health-based violations (Figure 10). This size category also has the highest percentage of consecutive CWSs in
violation, at 6.3 percent. The size category with the highest percentage of all CWSs in violation is the category
serving 3,301-10,000 people. At the time of the EPA's 2006 CWSs Survey, approximately 25 percent of all
PWSs serving fewer than 500 people did not disinfect (USEPA, 2006). Systems that do not disinfect or use
disinfected water do not need to comply with the Stage 2 DBPR, however this data has not been removed
from the analysis provided in Figure 10. As such the data presented overestimates the number of small
systems that need to comply with the Stage 2 DBPR and therefore the percentage violation data is higher.
The TTHM and HAA5 concentrations for those systems in violation exhibit a log-normal distribution
without a clear distinction for consecutive CWSs or contaminant type (Figure 11 and Figure 12). The
highest concentrations also appear to occur at both consecutive and non-consecutive systems that serve
approximately 1,000 people.
15
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 2
27,000
24,000
21,000
18,000
15,000
12,000
9,000
6,000
3,000
0
27,535
<=500
13,405
23.356
8.741
65.2%
501-3,300
5,002
Non-consecutive CWSs
Consecutive CWSs
2,672
53.4%
3,886
1 837
47*.3%
2,330
4d.6%
I 2.0491
I 52.7% |
196
54.5%
3,301-10,000 10,001-100,000 >100,000
Population Served
(n
c
o
'¦*->
ro
o
>
_i
o
CM
V)
%
o
o
V
n.
E
483
480
420
360
328
300
240
225
180
141
120
293
60.7%
196
90.9%
52.4%
39.0%
59.8
<=500
501-3,300
3,301-10,000 10,001-100,000 >100,000
61.0%
107
47.6%
132
40.2%
190
39.3%
Stage 2 DBPR MCL Violations
at Non-consecutive CWSs
Stage 2 DBPR MCL
at Consecutive CWSs
501-3,300 3,301-10,000
Population Served
10,001-100,000
~ 6%
<=500 501-3,300 3,301-10,000 10,001-100,000 >100,000
Population Served
Figure 10: Frequency of Stage 2 DBPR health-based violations at consecutive and non-consecutive CWSs of different
system size category in FY17. Graphs represent a) the national inventory of CWSs and shows that most CWSs serve
fewer than 500 people; b) illustrate that CWSs serving 501-3,300 people represent the system size category with the
most Stage 2 DBPR health-based violations; and c) shows that this size category also has the highest percentage of
consecutive CWSs in violation, 6.3 percent; for all the highest percentage was for those serving 3,301-10,000 people.
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Stage 2 DBPR and Consecutive System In-Depth Analysis
1.0
Chapter 2
8
O
T
° <£$• T
THM - Consecutive
THM - Non-Consecutive
0
1
1,000 100,000
Population
10,000,000
Figure 11: TTHM
concentration versus the
log of population size for
CWSs with a TTHM MCL
violation. The pattern
is very similar for both
consecutive and non-
consecutive CWSs, with
highest concentration
values above the MCL
occurring at a population of
roughly 1,000.
Figure 12: HAA5 concentration
versus the log of population
size for CWSs with a HAA5 MCL
violation. The pattern is very
similar for both consecutive and
non-consecutive CWSs, with
highest concentration values
above the MCL occurring at a
population of roughly 1,000.
re
>_
c
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o
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0.8
0.7
0.6
0.5
0.4
0.3
0.2
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o
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° HAA5 - Consecutive
q HAA5 - Non-Consecutive
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o
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1,000 100,000
Population
10,000,000
What about disinfection byproduct precursor removal (under Stage 1 DBPR)?
Disinfection byproduct precursor removal can be evaluated using total organic carbon (TOC) TT violations
data from SDWIS. Please keep in mind that only conventional treatment systems are required to monitor
for TOC removal whereas other systems, such as those using membrane filtration, do not need to meet
this requirement. Sixty-three CWSs had TOC TT violations in FY17 and of those 27 CWSs (43 percent)
had a simultaneous Stage 2 DBPR MCL violation. For CWSs with both a TOC TT and Stage 2 DBPR MCL
violation, most of these systems (70 percent) are located in Oklahoma and Puerto Rico. However, even for
those two states, only nine percent of systems with Stage 2 DBPR MCL violations also had simultaneous
TOC TT violations. The number of simultaneous violations is therefore relatively low, however remember
that not all systems that disinfect need to comply with the TOC TT requirement.
17
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Chapter 3:
Challenges, Lessons Learned,
and Best Practices
Information on Stage 2 DBPR compliance challenges and best practices was gathered during site visits
to the five partner states, in addition to feedback provided by ASDWA representing the combined input
from 32 additional states.
The following Stage 2 DBPR questions are used to organize this chapter:.
1. What approaches can a CWS take to
reduce DBP formation?
2. What are the best practices for
distribution sampling and analytical
methods?
3. What approaches can be used to
facilitate coordination between a
wholesale and consecutive system?
4. What capacity development tools can be
used to address DBP issues?
5. How can Drinking Water State Revolving
Fund (DWSRF) resources be used to
assist systems with DBP violations?
6. How can state enforcement be used to
help systems return to compliance?
7. What approaches can be used to
enhance operator training on DBP
compliance issues?
What approaches can a CWS
take to reduce DBP formation?
As described in SDWIS data analysis
presented in Chapter 2, most Stage 2 DBPR
compliance issues occur at CWSs using
surface water sources. During the EPA's
sites visits, the team observed that primarily
CWSs disinfecting with chlorine are facing
compliance challenges. Some consecutive
systems purchasing finished water that
was disinfected using chloramines have
been assigned violations; however, there are
multiple factors that may have contributed
to these violations (e.g., supplemental
State Approaches
Encourage wholesale systems to participate in
operational evaluation reports triggered by their
consecutive systems.
Proactively work with systems to optimize both the
distribution system and treatment plant processes
for compliance.
Coordinate with state enforcement programs to develop
a path for a system to return to compliance.
Provide operator training for representatives of systems
that have had Stage 2 DBPR compliance challenges to
share lessons learned with their peer group.
Stage 2 DBPR and Consecutive System In-Depth Analysis
18
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 3
disinfection). There have also been Stage 2 DBPR MCL exceedances at CWSs using ground water, although
based on sites visits these systems typically had extenuating challenges, such as areas of low demand
resulting in high water age or poor source water quality.
During the state site visits, the EPA observed a variety of issues related to treatment plant and distribution
system operations that contribute to TTHM and HAA5 MCL exceedances. Understanding the origin of Stage
2 DBPR problems is a critical step toward returning to compliance. For example, considering whether there
have been any changes to the source or distribution system that may impact DBP formation since the initial
distribution system evaluation (IDSE) was conducted. Other approaches a CWS can take to address DBP
formation are listed below.
Use of Chloramines
Several states indicate that many of their systems have gained DBP compliance through chloramination (e.g.,
Missouri, Indiana, South Dakota, and North Dakota). Chloramination is an effective distribution residual
strategy because it improves disinfection residual maintenance in distribution systems while addressing DBP
compliance. Switching from free chlorine to chloramines is a significant change to a water systems treatment
and a water system should insure that it has the necessary operational capacity to implement chloramination
and the customers are prepared for the transition. There are also simultaneous compliance concerns with the
use of chloramines, including nitrification in distribution systems. These can sometimes be addressed through
routine maintenance activities such as flushing programs. The Stage 2 DBPR requires the state be notified and
approve any significant treatment change, as determined by the state, prior to the PWS making the change.
Use of Pre-Chlorination
Due to limitations or constraints in treatment processes, some surface water systems are forced to pre-chlorinate
to achieve adequate contact time (CT), before they have removed DBP precursors (measured as TOC), to meet
Surface Water Treatment Rule (SWTR) requirements. Pre-chlorination before precursor removal has led to Stage
2 DBPR compliance issues in several states. A best practice is to review the need for pre-chlorination and to the
extent practical to avoid or reduce pre-chlorination (e.g., move the point of pre-chlorination further down the
treatment train). Profiling and benchmarking, as required in the suite ofSWTRs, is one tool a water system may
use to evaluate whether it would be possible to modify their treatment (i.e., point of pre-chlorination to reduce
contact time of the disinfectant with precursors), which may help with DBP formation. Where pre-chlorination
is necessary to achieve disinfectant CT, upgrades to the treatment plant, such as installing a post-treatment
contact chamber to provide the necessary CT, may be an option for achieving compliance.
Precursor Removal
As discussed in the data analysis presented in Chapter 2, most water systems meet the Stage 1 DBPR TOC removal
requirements in the treatment plant. There were examples of isolated events, such as algae blooms in reservoirs,
where increased TOC in the raw water challenged TOC removal efficiency. Use of the Alternative Minimum TOC
removal requirements varied by state [i.e., Step 2-40 CFR 141.135(b)(4)], As a best practice, Kentucky is reviewing
systems using Step 2 TOC removals to ensure the water systems are still optimized for TOC removal.
System Optimization
Water system optimization can be an effective tool to address DBP compliance
challenges. Kentucky and Pennsylvania both use optimization programs to evaluate
distribution system issues. Several programs exist to support water system optimization,
including EPA'sAWOP program and the American Water Works Association (AWWA)'s
Partnership for Safe Water, and provide opportunities for water systems to improve
their treatment performance. Kentucky uses the EPA sponsored AWOP approach to
help guide their efforts which considers both distribution system and treatment plant
19
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 3
issues. Kentucky has a state-required distribution system flushing program water systems use to address
Stage 2 DBPR compliance issues. Pennsylvania uses the AWOP approach for the distribution system and has
a separate filter plant performance evaluation (FPPE) that considers treatment plant optimization. The FPPE
evaluates the effectiveness of a drinking water treatment plant in removing disease-causing organisms from
the incoming raw water thorough an on-site survey of filter plant operations, equipment and water quality
conditions. A more detailed discussion of the AWOP approach is provided in Chapter 4.
Long hydraulic residence times
Long distribution systems and/or large storage tanks also create challenges for water systems in some states
where Stage 2 DBPR compliance issues develop in the distribution systems. As discussed in Chapter 2, this
may be one of the reasons for the greater rate of violations for consecutive CWSs. Many options are available
to reduce DBP formation in the distribution system related to water age management, reducing booster
disinfection, and water main flushing program (USEPA, 2007b). Specific water age management strategies
can include improving mixing and reducing water age in storage tank facilities, reducing water tank storage if
not needed, and reducing artificial dead ends in distribution system. Use of autoflushers is one way to create
artificial demand and is another way to reduce water age. Chapter 4 will discuss in more detail specific steps
that can be taken to address distribution system DBP formation.
What are the best practices for distribution sampling and analytical methods?
In many states, distribution sampling locations were selected based on the results in the IDSE and have not
been reviewed or updated. Sampling locations are typically only updated if there is a specific request from
the system due to a change in sampling access. Analytical results are another challenge identified by several
states. They described situations where sample results collected on either side of a system interconnection
could yield results that may be above or below the MCL. The accuracy/recovery for gas chromatograph (CC)
methods is +/- 20 percent for TTHM analysis and +/- 30 percent for HAA5 analysis. As a result, variability within
this range could be expected.
Distribution System Evaluation
Sampling locations in the distribution system may need to change due to changes in demand, water system
configuration, and storage or treatment (e.g., booster chlorination) within the distribution system. Most
states review these changes on an as needed basis based on discussion with the system. Some states review
these changes during sanitary surveys. In contrast, Alabama has a specific rule requirement to conduct a
distribution system evaluation (DSE) every nine years, unless the system meets the 40/50 exemption or serves
fewer than 500 customers (ADEM Administrative Code, 2017; r.555-7-2-.15). In addition, an updated DSE is
required if any of the following conditions apply
1. The system adds a new surface water or ground
water under the influence of surface water source;
2. New treatment plant that does not have the same
entry point as an existing water treatment plant;
3. The system adds a new well or spring that is
not considered to be in the same aquifer as the
existing water sources;
4. The system adds a new connection to another
system that will be used more than 60 days out
of the yean
5. The system consolidates with another system; or
6. The state requires the system to conduct
another DSE.
DBP Analytical Methods
The EPA recommends the following best practices
regarding TTHM and HAA5 analyses;
1. In addition to the existing analytical methods
(i.e., 502.2 or 551.11 identified in the Stage 2
DBPR, the EPA has identified new and improved
analytical methods (e.g., 552.5. 524.5. and 524.4).
which require multi-lab validation. These
methods need to be adopted by the state in
order to be used for compliance determination;
20
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Stage 2 DBPR and Consecutive System In-Depth Analysis
2. Ensure that samples are properly preserved and
holding times are met (i.e., 14 days forTTHM and
28 days for HAA5);
3. Ensure that samples are collected at comparable
times and analyzed using similar methods; and
Chapter 3
4. Review supporting data for quality assurance (QA)
and quality control (QC) checks. QC should use a
matrix spike and recovery should be
+/- 30 percent.
What approaches can be used to facilitate coordination between a wholesale
and consecutive system?
States typically have limited regulatory authority over contracts between wholesale and consecutive PWSs
and these are typically related to the quantity of the water provided, rather than the quality. Contracts
between wholesale and consecutive PWSs can last as long as 99 years, or may auto-renew, and last even
longer. As a result, when the consecutive system has compliance issues with the NPDWRs, especially those
related to Stage 2 DBPR, communication can become a challenge as the wholesale system may mention
that they are meeting the requirements of the contract.
Consecutive PWS Purchase Agreements
While most states do not review purchase agreements, Texas does review them during sanitary surveys, and
other states (e.g., Wisconsin, Virginia, and Montana), review them upon request. Vermont requires water
allocation agreements and Connecticut requires a permit for the sale of excess water between wholesale
and consecutive PWSs. Minnesota has an interconnection policy for CWSs and recommends submission of a
Community Public Water System Interconnection Plan prior to entering into a purchase agreement (MDOH,
2019). Michigan reviews new agreements but does not have a formal approval process. Additional feedback
on this topic was provided from the following states:
Iowa— Requires that an agreement
between the wholesale and
consecutive PWSs be provided
as part of DWSRF projects. For
non DWSRF projects, there is a
construction schedule entitled
"Water Service Agreement" (Iowa
Form 542-3121), that must be signed
and submitted by both parties.
North Carolina—Worked with the
North Carolina Environmental Finance
Center (EFC) to create a guidance document
on purchase water contracts/agreements (UNC
EFC, 2019). The state receives copies of the
contracts/agreements when a system requests
approval for a new source of supply. Only the
establishment of the contract/agreement is
required. The content of the contract/agreement
is not subject to approval by the state.
Massachusetts—Has a
PWS coverage provisions,
similar to that provided at
40 CFR 141.3, however it
includes a fifth element
that says:
The consecutive
system and the supplying
system have entered into
a written agreement that
addresses the status and
responsibilities of the par-
ties for the ownership, op-
eration and maintenance
of the combined system,
including but not limited
to, drinking water sources,
treatment facilities, distri-
bution system, storage and
water quality sampling.
This ensures that monitoring
requirements for the consecu-
tive watersystem are appropriate.
21
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 3
Purchase Agreements Addressing Water Quality
Our review did not identify any state requirement for a wholesaler
purchase agreement to address water quality. However, inclusion
of contract clauses or requirements that the wholesaler will provide
water that meets federal and state standards is a best practice that
occurs in many states (e.g., Wisconsin, Virginia, Kansas. Montana,
Hawaii. Louisiana, Alabama, and Iowa) Some states also use their
requirements for a system interconnection as an opportunity to
evaluate water quality. Specific examples are detailed below:
Colorado—The integrated Systems Rule [Section
11.42(4)] of the state's Primary Drinking Water Regula-
tions allows wholesalers to assume responsibility for
drinking water compliance for one or more regulato-
ry requirements applicable to the consecutive PWS.
As part of this rule, PWSs must apply for "integration".
They must also include other required information
(e.g., distribution system
maps, sampling plans, copy
of the agreement between
the interested parties). Colo-
rado is required to review the
submittal and either approve
or deny the pplication.
Minnesota— Under Minnesota Admin-
istrative Rule (4720.0040), Minnesota
Department of Health must approve
interconnection agreements be-
tween municipalities. Water quality
issues are expected to be addressed
in all interconnection plans, includ-
ing water age, corrosion control, and
communication plans that address
problems as they occur.
Iowa— Purchase agreements include the following phrase
requiring potable water that meets the Code of Iowa require-
ments as well as the Iowa Administrative Code rules:
/ am the authorized representative of the Owner of the water
system identified above and state that the connection of the
proposed water distribution system also identified above is
approved by the owner, and that the owner accepts respon-
sibility for providing potable water required by this project in
accordance with the provisions of Chapter 455B, Code of
Iowa, and the rules of the Department of Natural Resources.
This agreement shall not be construed in any way to affect
any local ordinances, water service agreements, or fee
systems entered into between the parties.
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 3
Joint Operation Evaluation Level Involvement
Some states have improved the value of the Operation
Evaluation Level (OEL) by integrating the wholesale
system into the evaluation process. A few states have
developed specific state rule requirements to have
wholesale systems conduct an OEL when it is triggered
by their consecutive PWSs. in Alabama if a consecutive
PWS has a DBP (TTHM or HAAS) violation, regardless
of the results at the interconnection, the wholesaler
must participate in a joint OEL (ADEM Administrative
Code, 2017; r.335-7-2-.16). Tennessee only requires the
wholesale system's involvement when sampling at the
interconnection is greater than 60 percent of the MCL;
wholesale and consecutive PWSs must then jointly
submit the required OEL report, including the steps
to be implemented to eliminate future exceedances
(TDEC, 2019; Chapter 0400-45-01-.36), Virginia requires
a consecutive PWS to have its wholesaler complete
the source and treatment sections of the OEL report
Tennessee—Requires
wholesalers and consecutive ;
systems using water with
either an MCL or OEL DBP
exceedance, or any other
systems designated by the state,
to conduct quarterly monitoring
for chlorine, pH, DBPs and other
water quality indicators as necessary. This sampling
shall occur at or near the master meter having the
highest annual arithmetic mean concentration for
TTHMs or HAA5s with all systems reporting their
test results to each other. Parent and consecutive
systems shall coordinate sampling activities so that
samples are collected on the same date or a date
prescribed by the state. (TDEC, 2019; Chapter 0400-
45-01-.36).
Communication between Wholesale
and Consecutive PWSs
States have found
success when regular
meetings are held
between wholesalers
and their consecutive
PWSs to address Stage
2 DBPR compliance
issues. North Dakota
that is submitted to the state. In New Jersey when a
consecutive system triggers an OEL, the state requires
the consecutive system to complete a full OEL Report
with their wholesale system. Other states did express
that OELs can, however, serve as good conversation
starter for discussions between consecutive and
wholesale systems, and technical assistance providers,
or state regulators.
Sampling at the Interconnection
While not required by the Stage 2 DBPR, sampling
at the interconnection is a best practice that is
recommended by many states. This practice informs
the scope of the water quality problem when the
consecutive system triggers an OEL or has an MCL
violation. Some states require sampling at the
wholesale and consecutive PWS Interconnection,
especially if triggered by consecutive PWSs' results as
detailed below:
North Dakota and Ohio— Require their wholesale
systems to conduct special purpose sampling at
the inter-connection when a
sample exceeds or approaches
the MCL in the consecutive PWS.
Alabama—'Wholesale systems
(except systems with only
ground water sources), as well as
consecutive systems that sell to
other consecutive systems, must
submit the results of TTHM and
HAA5 sampling at or near all
points of delivery to consecu-
tive systems (ADEM Admini-
strative Code, 2017; r.335-7-2-,12).
and Indiana indicated that getting wholesale and
consecutive PWSs in the same room is a critical
step towards identifying, and ultimately addressing,
the root cause of the DBP issue. In their rule
language, Alabama requires representatives from all
systems involved to meet quarterly to evaluate the
effectiveness of the measures implemented based
on the joint OEL findings (ADEM Administrative
Code, 2017; r.335-7-2-,16).
23
It
f
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 3
Many states encourage and facilitate conversations
between wholesalers and their consecutive PWSs,
even when they are not required. When an OEL
is triggered in Iowa or Illinois, consecutive PWSs
and their wholesalers discuss possible source and
treatment factors that could have elevated the
results. State representatives get involved if needed.
Virginia uses sanitary surveys as an opportunity
to discuss cooperation between wholesale and
consecutive PWSs and make recommendations to
improve communication.
What capacity development tools can be used to address DBP issues?
Many PWSs with DBP compliance challenges often have TMF issues. Support for those PWSs through
technical outreach and optimization programs was common and is generally found to be helpful in the
states where it is provided; many states fund this through the capacity development set asides. Missouri's
capacity development program prioritizes systems with elevated DBP concentrations for technical assistance
under the EPA Training and Technical Assistance (T/TA) Grant. Iowa uses TA providers to implement tools
such as maximizing removal ofTOC, use of chlorine dioxide to remove additional organics, use of chloramines
instead of free chlorine for distribution system residual, managing waterage through flushing programs and
managing elevated storage tanks, especially during hot weather.
Other states have used their set aside money to undertake special studies and map water distributions
systems to address DBP issues. Examples include Kansas which is working with the EPA Region 7 to
complete a special study sampling DBPs for consecutive PWSs and New York which has mapped water
system boundaries for systems of concern and made this information available on state's Department of
Health website. More detailed examples of other approaches are provided below:
Missouri— Has funded university researchers to perform a
comprehensive study of the chemical characteristics of water for
systems with DBP compliance challenges. Systems are selected after
they have been determined to be open to findings of the report and
willing to consider treatment plant process changes. Researchers
consider coagulant types, feed rates, feed locations and how DBP
concentrations are impacted throughout the plant and distribution
system. These comprehensive studies have been carried out for
approximately 20 PWSs, with about three per year being completed.
The studies are helpful and identify numerous strategies PWSs can
try such as: auto flushers; aerators in tanks; re-
plumbing tanks; keeping tanks at a lower level;
taking storage off line if it is not needed; making
sure tanks are painted white, recalculating CT
to make sure chlorine is not being overfed; and
covering basins to reduce chlorine demand.
Texas—Has provided technical
assistance by sending Texas
Optimization Program staff to
wholesale and consecutive PWSs
to approach their issues with
a holistic view. Assistance
typically involves a review and
analysis of historical data to
identify any trends, an on-site
review of the treatment process, additional
sampling outside of compliance schedules
for process control information, and
additional specialized studies based on the specific needs
and demands of the system receiving the assistance.
k
Vermont— Has a part-
time staff member
providing direct
technical assistance
to PWS with wa-
ter quality issues.
This often includes
DBP formation and
removal of DBP
precursors. Through
this position, the
state has been able
to monitor ultravio-
let (UV) absorbance
at certain PWSs and
implement manage-
ment initiatives. For
example, this review
may suggest op-
erationally changing
how the system re-
ceives incoming raw
water, for example
only drawing from a
stream at night dur-
ing spring snowmelt
or diverting from a
fast-moving stream
instead of pulling
from a reservoir.
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Stage 2 DBPR and Consecutive System In Depth Analysis Chapter 3
How can DWSRF resources be used to assist systems with DBP violations?
For some PWSs, capital improvements may be necessary to address the root cause of the DBP issue.
Connecting these systems with the DWSRF can assist them to return to compliance. As part of the
ranking criteria many states use heath-based violations as a scoring mechanism to prioritize funding.
The DWSRF program has recently developed two fact sheets highlighting eligible activities and specific
projects that have been funded in the past to address DBP violations (USEPA, 2019a; USEPA, 2019b). A
few DWSRF specific programs elements related to Stage 2 DBPR are detailed below:
%
Oklahoma— Is in the process of using
20 percent of the DWSRF Grant as its
mandated subsidy to provide $100,000
loans that are forgiven to address Stage 2
DBPR issues. The state is using other funds
to contract with a bond attorney for these
small forgiven loans to keep costs down.
The state is also creating a pre-qualification
list of engineers experienced in DBP
treatment. PWSs will select an engineer
from this list unless they already have an
engineer under contract. Oklahoma
Department of Environmental Quality
(ODEQ) will meet with the wholesale
system along with its consecutive PWSs
to update sample site plans and see
if purchased water is in compliance as it enters the consecutive PWS. ODEQ
wili give the $100,000 subsidy as its first priority to the wholesale system to
see if the DBP issue can be resolved for both the wholesale system and its
consecutive PWSs. They anticipate this program will start obligating money
during the spring of 2019.
Wisconsin— Has incentivized
asset management by giving
principal forgiveness points for
approved plans (Wisconsin De-
partment of Natural Resources,
2019). Plans must include infra-
structure inventories (includ-
ing maps) that provide pipe
length, age, diameter, condi-
tion, and location, as well as
valve and hydrant location and
age. These maps can be used
to determine problem areas
for Stage 2 DBPR compliance.
How can state enforcement be used to help systems return to compiiance?
Systems with historical significant compliance issues benefit from a proactive enforcement program that
provides a path toward compliance. Typically, these systems require substantial assistance from their states
and technical assistance providers. For example, Kentucky's enforcement program works closely with the
drinking water program staff to develop enforcement orders that seek to identify and address the root cause
of the issue. Typically, this involves using the approaches adopted by the state's optimization program to
develop a path to compliance. In states with a small number of Stage 2 DBPR violations these are typically
handled on a case-by-case basis due to the low frequency ofTTHM and HAAS MCL violations. Other states
provided additional proactive enforcement examples are provided in the following graphic.
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 3
Montana— Had a PVVS voluntarily
enter into an Administrative
Order on Consent (AOC)
that included a work plan
and deadlines to resolve the
problem. This provided the
PWS with the time needed to
make changes without incurring
additional violations.
Colorado— Has found that close
collaboration between the regulat-
ing agency and the PWS can lead to
short-term solutions that immediately
protect public health (e.g., flushing programs, improved
tank storage), while long-term solutions are being de-
signed and funded (e.g., improved treatment processes for
TOC removal and chlorination). They also indicated that
intra departmental collaboration on DBP enforcement cases
is critical, coupled with the willingness to work with the PWS
on acceptable DBP treatment methods. This can help pro-
tect public health and resolve DBP-related challenges often
with timely and low-cost solutions.
North Carolina—Approximately two years ago,
developed a new and still evolving MCL en-
forcement process that has focused primarily
on DBPs, as these systems often fail to meet
Administrative Order (AO) deadlines. The big-
gest change has been an enforcement process
escalation protocol for unresolved MCLs.
Oklahoma— Issued 140 consent
orders from 2016 to 2017 to address
DBP exceedances. The consent orders
have a schedule for returning to com-
pliance. These PWSs are in the pro-
cess of completing tasks that include
an operational corrective action plan,
engineering report, plans and specifi-
cations, construction, and monitoring.
What approaches can be used to enhance operator training on DBP
compliance issues?
Providing operator training from those who have experienced Stage 2 DBPR compliance issues has proven to
be a successful approach. A few examples are provided below.
North Dakota—At their annual state conference, North
Dakota organizes a panel of operators from small, medium,
and large systems who have
dealt with common challenges.
These panelists present their
approaches to dealing with the
identified DBP problems. This peer
training helps put the challenge in
the operator's language and
knowledge framework.
Colorado— Has a training
workgroup that evaluates
DBP compliance trends
and works with systems
that have exceeded or are
Missouri— In 2017, the state provided one-
day training courses that focused on how
to reduce DBPs at nine different locations
in the state. Compliance data were used to
target the locations of the courses, which
were funded through the EPA's T/'TA Grant.
approaching compliance limits. The workgroup has developed DBP training material to help these systems
evaluate their water quality and find potential source, treatment, and distribution solutions. Colorado has had
tremendous success working with systems one-on-one and has been able to help a handful of systems return
to compliance by making operational changes. Small system operators have been educated on various solutions
and their relative costs so the systems are in a better position to work with their engineers if new treatment
and/or infrastructure are needed. Additionally, Colorado has partnered with the local American Water Works
Association (AWWA) section to provide classroom-style DBP training.
26
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Chapter 4: Approaches to Reduce DBPs
through Optimization
Detailed below is a general approach to reduce DBPs that has been developed through pilot projects and
field studies carried out by the EPA Office of Ground Water and Drinking Water's Area Wide Optimization
Program (AWOP). AWOP formalizes these activities and encourages states to implement optimization
concepts. The program also provides a network of participating states that can collaborate on optimization
activities and on the implementation of elements of their state drinking water programs. Involvement with
AWOP can enhance a state's ability to provide technical assistance to PWSs that are challenged with DBPs.
Presently 29 states are active or limited AWOP participants, and about half of these are using it for DBP
optimization. States and PWSs that are not formally involved with AWOP can still successfully implement
these concepts. Additional information about AWOP can be found in the references section of this document
(USEPA, 2019c).
What is the AWOP DBP optimization approach?
The overall AWOP DBP approach, shown in Figure 13,
includes both treatment plant optimization (shown
on the left) and distribution system optimization
(shown on the right). It is important to recognize that
some PWSs need to work on both treatment plant
and distribution system optimization to achieve
compliance or their treatment goals.
For Stage 2 DBPR issues, treatment plant
and distribution system optimization may
both be effective forTTHM reduction in
CWSs and non-transient non-community
water system (NTNCWSs) that disinfect with
chlorine. However, CWSs and NTNCWSs
disinfecting with chloramines may also
optimize their treatment to lower DBP
formation prior to adding ammonia and
manage water age to provide better
disinfectant residual maintenance. Typically,
HAA5 may only be reduced through
treatment plant optimization.
If a PWS has already pursued DBP operation
practices (e.g., stopped prechlorination, enhanced
TOC removal, minimized water age in the distribution
system), they may not have the potential to reduce
DBPs. Under such circumstances, experience with
optimization efforts and associated data will support
the process of identifying and implementing any
capital improvements.
AWOP teaches skills to improve water
system operations, rather than focusing
on costly capital improvements.
Stage 2 DBPR and Consecutive System In-Depth Analysis
27
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OPTIONAL- -
System is not in compliance
with DBPR rule.
Conduct DS influent hold study
(duration = system's MRT).
Begin diagnostic monitoring at DS
entry point and MRT locations.
MRT
DS
Does the DS influent EP
hold study indicate the bulk water
is very reactive?
Maximum Residence Time
Distribution System
Entry Point
Are plant effluent
TTHMs > 30 ppb?
NO YES
(start in the DS) (start in the plant)
In-Plant DBPR Optimization
DS TTHM Optimization
Are TTHMs
< MCL?
Are
TTHMs < plant effluent
goal?
Are there
any remaining
plant-based control
strategies?
Are there
any remaining DS control
strategies?
Are TTHMs
< MCL?
Are there
any remaining DS control
strategies?
Are there
any remaining
plant-based control
strategies?
Prioritize, then evaluate
DS control strategy.
Prioritize, then evaluate
in-plant control strategy.
Optimization is probably
not the solution; consider capital
improvements for
DBPR control.
Continue monitoring at EP
and compliance locations to assess
performance.
Figure 13: Frequency of Stage 2 DBPR MCL violation types at consecutive and non-consecutive CWSs (FY17). TTHM MCL
violations (TTHM and TTHM/HAA5 MCL violations added together) account for more than 80 percent of the systems with
Stage 2 DBPR health-based violations. This pattern is true for both consecutive and non-consecutive systems.
Stage 2 DBPR and Consecutive System In-Depth Analysis 28
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 4
How do you diagnose DBP formation and water quality stability?
This first step of the optimization process involves
diagnostic monitoring and conducting a plant
effluent hold study.
The goal of diagnostic monitoring is to identify if
DBPs are predominantly forming in the treatment
plant, in the distribution system or in both places
(Figure 14). Monitoring is conducted at the entry
point to the distribution system (i.e., the treatment
plant effluent), at consecutive PWS interconnections
and at distribution system locations where
maximum DBP concentrations have
been found (e.g., at the Stage 2 DBPR
maximum residence time location).
Additionally, a hold study can also be
performed to assess the reactivity of
the water (i.e., water quality stability).
Treatment plant effluent samples are
collected and held for a period of time
before they are analyzed to measure disinfectant
decay and/or DBP formation. If the water is very
reactive, additional treatment may be needed. Hold
studies do not assess pipe wall reactions.
Results of both studies are used to prioritize efforts
and identify whether to first focus on the treatment
plant or the distribution system. Often, both
treatment plant and distribution system can benefit
from optimization efforts.
A hold study is a useful tool when
determining if the system should focus
on DBP control strategies at the plant or
within the distribution system. A hold study
can help water systems identify if chlorine
degradation issues are from distribution
system deficiencies
Coagulant
Addition
4
Disinfectant
Addition
Oxidant/
Disinfectant
Addition
Coagulation
4
cm
Sedimentation
Disinfectant
Addition Maintain CT
iy and DS residual
Filtration
Figure 14: A schematic diagram of a conventional treatment plant.
Disinfection Barrier
What can be controlled in the treatment plant?
Evaluating how a treatment plant is being operated can reveal additional ways DBPs and their precursors
may be reduced (Figure 15). Key operational treatment changes that can impact DBP formation include
optimizing preoxidation and improving DBP precursor removal.
Optimizing preoxidation strategy to eliminate prechlorination (if applicable) and utilize an effective oxidant/
dose. Note that prechlorination is defined as chlorine addition prior to TOC removal, which generally
occurs through the coagulation/flocculation/sedimentation process. Many systems require some type of
preoxidation (e.g., permanganate, chlorine dioxide, other) to meet their overall water quality objectives, and
this should be maintained/enhanced. If pre-chlorination is eliminated, the PWS must ensure there is enough
intermediate disinfection to maintain disinfection CT and provide sufficient treatment plant effluent residual.
29
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 4
Improving DBP precursor removal by reducing finished water TOC can be accomplished through optimized
coagulation. PWSs that use surface water or ground water under the direct influence of surface water and
conventional filtration treatment are required under the Stage 1 DBPR to remove specified percentages of
organic materials (measured as TOC) that may react with disinfectants to form DBPs. Some systems are able
to achieve additional TOC removal, which will likely result in lower DBP formation. Additional, or optimized,
TOC removal is generally achieved through some combination of changing coagulant dose or pH, and/or
utilizing an alternate coagulant.
Treatment-based strategies for controlling DBPs are
prioritized by conducting disinfection benchmarking
and profiling for the plant, as required under the
SWTR, conducting a plant profile (i.e., sampling
disinfectant, pH, temperature, TOC, UV254, and DBPs),
and analyzing historical water quality (i.e., reviewing
raw and finished water TOC, coagulant dose and pH,
disinfectant dose and residual). Secondary impacts
of each DBP control strategy must be considered to
prevent unintended consequences or simultaneous
compliance issues, especially related to the SWTR
and the Lead and Copper Rule (LCR). For example,
optimizing the use of oxidants and/or disinfectants for
DBP control might:
¦ Lower disinfection CT and/or distribution system
disinfectant residual;
¦ Reduce the treatment plant's ability to meet
inorganic oxidation demands (e.g., iron or
manganese oxidation and removal goals);
¦ Change finished water pH which could impact
corrosion control optimization under the LCR;
¦ Impact treatment strategies for harmful algal
blooms; and/or
¦ Allow for increased in-plant biogrowth.
Optimizing DBP precursor removal might;
¦ Require additional corrosion control due to a
change in coagulation chemistry
¦ Change the quantity and/or quality of the
treatment sludge; and/or
¦ Reduce manganese removal due to lower
coagulation pH.
Disinfectant
Addition
Coagulant
Addition
Disinfectant
Addition
Maintain CT
and DS residual
Oxidant/
Disinfectant
Addition ,
Coagulation
Flocculation
Sedimentation
Filtration
Disinfection Barrier
Treatment steps where DBP precursor removal takes place
Systems should ensure they continue to provide
adequate CT and DS residual.
Figure 15: Common approaches to reduce DBP formation include optimizing preoxidation strategy by reducing or
eliminating pre-chlorination (shown in red) and increasing precursor removal in the treatment process (shown in green);
often a combination of both strategies is necessary.
30
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Stage 2 DBPR and Consecutive System In-Depth Analysis
Chapter 4
JI^and sbBS?*.
What can be controlled in the
distribution system?
Distribution system optimization strategies for
controlling DBPs are primarily related to reducing
water age. These strategies can be utilized by a
parent or consecutive PWSs. As with the treatment-
based strategies, unintended consequences
associated with distribution system optimization
must be considered. DBP control strategies can
be prioritized through investigative sampling
(primarily disinfectant residual) to identify critical
locations, assessing storage tank performance and
water quality, and conducting additional water
quality monitoring in and around tanks. Some
strategies include modifying storage tank operations,
distribution system flushing program, and modifying
distribution system hydraulics. Minor distribution
system design changes or treatment (e.g., installation
of a mixing orTHM aeration system) may also be an
effective strategy
If DBP issues are localized following a water storage
tank (Figure 16) it would be appropriate to evaluate
the tanks operations and maintenance. General
approaches can include modify tank levels, change
fill rate and/or duration, remove tank(s) from service,
and ensure that tank maintenance is adequate.
A distribution system flushing program (Figure 17)
can have several objectives with different impacts on
water quality depending on the type of program a
system implements. For example, automatic flushing
is intended to create "artificial demand" and reduce
water age in the distribution system by strategically
flushing older, stagnant water on a periodic basis,
whereas unidirectional flushing intends to scour
lines and potentially reduce chlorine demand
and DBP precursors, typically on an annual basis.
Modest flushed water volumes can suffice to replace
stagnant water with higher quality water to minimize
DBP formation and maintain chlorine residual.
Figure 16: A water storage tank.
Changing how water moves through a distribution
system can also be an effective approach to
reduce hydraulic retention times and minimize
DBP formation. Modifying system hydraulics is a
particularly effective strategy for systems that can
reroute flow through a low demand area to an area
of higher demand (i.e., areas with parallel lines and/or
operational flexibility).
Existing treatment in the distribution system can
sometimes be improved for DBP control,
31
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Stage 2 DBPR and Consecutive System In Depth Analysis
for example, booster disinfection that is already in
place can be optimized. At times, however, treatment
modifications are needed and capital improvements
that focus on impacting distribution system water
quality may be warranted.
The highest priority strategy should be implemented,
being mindful of unintended consequences or
secondary impacts, which might include (but are not
limited to):
¦ reduced capacity for peak demands;
Chapter 4
¦ potential hydraulic challenges associated with
rerouting water and pumping changes; and
¦ political or consumer concerns (i.e., from
taking tanks out of service, related to flushing
and water conservation concerns, dirty water
complaints).
Figure 17: Distribution system autoflusher
¦ low water pressure due
to reduced tank levels;
32
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Additional Resources and References
Additional Resources
¦ Stage 2 DBPR Implementation Guidance
This EPA guidance (USEPA, 2007a) for the EPA Regions and states explains how the EPA interprets the
Stage 2 DBPR and provides guidance to the public and the regulated community on implementing the
statute and regulations.
¦ Stage 2 DBPR Consecutive Systems Guidance Manual
This EPA guidance (USEPA, 2010) is intended specifically to help consecutive CWSs understand and
meet the requirements of the Stage 2 DBPR.
¦ Simultaneous Compliance Guidance Manual for the Long Term 2 and Stage 2 DBP Rules
This EPA guidance (USEPA, 2007c) discusses the issues systems may face as they evaluate and
implement changes necessary to comply with the Microbial and Disinfection Byproduct (M-DBP) Rules;
specifically, Chapter 4 of this document focuses on potential Lead and Copper Rule compliance issues.
¦ Stage 2 Disinfectant and Disinfection Products Rule: Operational Evaluation Guidance Manual
This EPA guidance manual guidance provides technical information on completing an operational
evaluation as required by the Stage 2 DBPR.
¦ Evaluation of Disinfection Practices for DBPs and Precursor Occurrence in Consecutive Systems
This Water Research Foundation paper (Chowdhury et al„ 2008), co-sponsored by the EPA, characterizes
DBPs and DBP precursor occurrence in consecutive CWSs that acquire treated water from a larger-
system wholesaler and provides suggestions regarding how to identify acceptable DBP level goals
for consecutive CWS entry points, strategies for consecutive CWSs to reduce DBP concentrations, and
recommendations for negotiations between consecutive CWSs and wholesalers. http//www.waterrf.org/
Pages/Projects. aspx?PID=3026
¦ Decision Tool to Help Utilities Develop Simultaneous Compliance Strategies. Available at:
http://www.waterrf.org/PublicReportLibrary/91263.pdf
References
ADEM Administrative Code. 2017. Alabama
Department of Environmental Management, Water
Division, Water Supply Program, r. 335-7. Available at:
http://www.ad em.sta te.a I.us/a IE nvi ro Reg Laws/fi I es/
Division7.pdf
Alexander, M.T., AG. Dugan, D.G. Wahman. 2019.
Using a Hold Study to Assess Distribution System
Influent Water Quality. Opflow, https://doi.org/
10.1002/opfl.ll87
Chowdhury, Z.K., C.P. Hill, F. Mahmood, MJ. Sclimenti,
S.W. Krasner, R.S. Summers, C. Valenti. 2008.
Evaluation of Disinfection Practices for DBPs and
Precursor Occurrence in Consecutive Systems.
AwwaRF Report 91245. Project #3026. American
Water Works Association Research Foundation,
Denver, CO. http//www.waterrf.org/Pages/Projects.
aspx?PID=3026
MDOH. 2019. Community Public Water System
Interconnection Plan (Excel document). Available at:
https://www.health.state.mn.us/communities/
environment/water/com/com.html
TDEC. 2019. Rules of Tennessee Department of
Environmental Conservation Division ofWater
Resources, Chapter 0400-45-01 Public Water
Systems. Available at: https://publications.tnsosfiles.
com/rules/0400/0400-45/0400-45.htm
UNC EFC. 2019. Crafting Inter-Local Water
Agreements: Tips Relating to Issues You May Not
Have Thought of or that You Were Hoping to Avoid.
Web resource available at: https://efc.sog.unc.edu/
resource/crafting-inter-local-water-agreements-tips-
relating-issues-vou-may-not-have-thought-or-you
33
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Stage 2 DBPR and Consecutive System In-Depth Analysis
USEPA. 1995. Method 502.2: Volatile organic
compounds in water by purge and trap capillary
column gas chromatography with photoionization
and electrolytic conductivity detectors in series,
revision 2.1. Cincinnati, OH.
USEPA. 1995. Method 551.1: Determination of
chlorination disinfection byproducts, chlorinated
solvents, and halogenated pesticides/herbicides in
drinking water by liquid-liquid extraction and gas
chromatography with electron-capture detection,
revision 1.0. Cincinnati, OH.
USEPA. 2003. Method 552.5: Determination of
haloacetic acids and dalapon in drinking water by
liquid-liquid microextraction, derivatization, and gas
chromatography with electron capture detection,
revision 1.0. Cincinnati, OH. EPA 815-B-03-002.
USEPA. 2009. Method 524.5: Measurement of
Purgeable Organic Compounds in Water by Capillary
Column Cas Chromatography/Mass Spectrometry
revision 1.0. Cincinnati, OH. EPA 815-B-09-009.
USEPA. 2013. Method 524.4: Measurement of
purgeable organic compounds in water by gas
chromatography/mass spectrometry using nitrogen
purge gas, revision 1.0. Cincinnati, OH. EPA 815-R-
13-002.
USEPA, 2006. 2006 Community Water System Survey
Volume II: Detailed Tables and Survey Methodology.
EPA 815-R-09-002. U.S. Environmental Protection
Agency, Office of Water, Washington, DC.
USEPA. 2007a. Stage 2 Disinfectants and Disinfection
Byproducts Rule Implementation Guidance. EPA
816-R-07-007. U.S. Environmental Protection Agency,
Office of Water, Washington, DC.
USEPA. 2007b. Simultaneous Compliance Guidance
Manual for the Long Term 2 and Stage 2 DBP Rules.
EPA 815-R-07-017. U.S. Environmental Protection
Agency, Office of Water, Washington, DC.
USEPA. 2010. Stage 2 Disinfectants and Disinfection
Byproducts Rule Consecutive Systems Guidance
Manual. EPA 815-R-09-017. U.S. Environmental
Protection Agency, Office of Water, Washington, DC.
USEPA. 2019a. Addressing DBPs in Drinking Water
with the Drinking Water State Revolving Fund. EPA
810-F-19-002. U.S. Environmental Protection Agency,
Office of Water, Washington, DC.
USEPA. 2019b. DWSRF Case Studies: DBPs in
Drinking Water. EPA 810-F-l9-001. U.S. Environmental
Protection Agency, Office of Water, Washington, DC.
USEPA. 2019c. Optimization Program for Drinking
Water Systems Website.
Wisconsin Department of Natural Resources.
2019. Department-Approved Asset Management
Plans SFY 2020 SDWLP Principal Forgiveness
Points. Special PUB-CF-034. Available at:
https://dnr.wi.gov/Aid/documents/EIF/news/
SDWLPFY19AMPIanPWSPartPFCriteria.pdf.
34
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Acronyms
AOC Administrative Order on Consent
AO's
Administrative Orders
ASDWA
Association of State Drinking Water Administrators
AWOP
Area Wide Optimization Program
AWWA
American Water Works Association
CT
Product of disinfectant concentration (C) and contact time (T)
CWS
Community Water System
DBPR
Stage 2 Disinfectant and Disinfection Byproduct Rule
DBP
Disinfection byproduct
DS
Distribution System
DSE
Distribution System Evaluation
EFC
Environmental Finance Center
EPA
U.S. Environmental Protection Agency
ETT
Enforcement Targeting Tool
FY
Fiscal Year
CC
Cas Chromatograph
GWR
Ground Water Rule
HAA5
Haloacetic Acids (Five)
HRL
Health Reference Level
IDSE
Initial Distribution System Evaluation
IOC
Inorganic chemicals, including arsenic
LCR
Lead and Copper Rule
LRAA
Locational Running Annual Average
LT2ESWTR
Long Term 2 Enhanced Surface Water Treatment Rule
MCL
Maximum Contaminant Level
MRDL
Maximum Residual Disinfectant Level
N03
Nitrate Rule
NPDWR
National Primary Drinking Water Regulation
NT N CWS
Non-Transient Non-Community Water Systems
OELs
Operational Evaluation Levels
ppb
Parts Per Billion
PPm
Parts Per Million
PWS
Public Water System
Rads
Radionuclides Rule
RTCR
Revised Total Coliform Rule
SDWA
Safe Drinking Water Act
SDWIS
Safe Drinking Water Information System
Stage 1 DBPR
Stage 1 Disinfections and Disinfection Byproducts Rule
Stage 2 DBPR
Stage 2 Disinfections and Disinfection Byproducts Rule
SWTR
Surface Water Treatment Rules
T/TA
EPA Training and Technical Assistance
TMF
Technical, Managerial, and Financial
TNCWS
Transient Non-Community Water System
TOC
Total Organic Carbon
TT Treatment Technique
TTHM
Total Trihalomethanes
UV Ultraviolet
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