United States         Office of Water
        Environmental Protection      (4606)
        Agency
vxEPA   Stage 1  Disinfectants/
        Disinfection Byproducts Rule

        Frequently Asked Questions

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                                   TABLE OF CONTENTS
1.0  Stage 1 Disinfectants/Disinfection Byproducts Rule  	5
1.1    Disinfectants	5
       1.1.1   Chlorine and Chloramines  	5
       1.1.2   Chlorine Dioxide	6
1.2    Disinfection Byproducts	7
       1.2.1   TTHM and HAAS	7
       1.2.2   Bromate	12
       1.2.3   Chlorite  	13
1.3    Disinfection Byproduct Precursors	14
1.4    Monitoring	20
       1.4.1   General Monitoring Issues	20
       1.4.2   Monitoring Plans	21
       1.4.3   Multiple Wells Drawing from a Single Aquifer	22
       1.4.4   Reporting and Recordkeeping	22
       1.4.5   Consecutive Systems	23
2.0  General Program Requirements	23
2.1    Primacy	23
2.2    Violations, SDWIS Reporting and SNC Definitions  	24
2.3    Qualified Operators	24

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Stage 1 DBPR FAQs                                                                           Page 4

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1.0   Stage 1 Disinfectants/Disinfection Byproducts Rule
1.1  Disinfectants

     1.1.1     Chlorine and Chloramines

         For further information, see the following rule sections:
     Q:
    A:
Citation
141.32(e)(76),(77)
141.201
141.54
141.65
141.131(c)(l),(2);(3)
141.132(c)(lXi),(ii);(iii)
141.133(c)(l)(i),(ii)
141.134(c)
Part Title
Public Notification
Public Notification of Drinking Water Violations
Maximum Residual Disinfectant Level Goals
Maximum Residual Disinfectant Levels
Analytical Requirements
Monitoring Requirements
Compliance Requirements
Reporting and Recordkeeping Requirements
Under the Surface Water Treatment Rule water systems can measure heterotrophic plate counts
(HPC) in lieu of chlorine residuals. If the results of the HPC are acceptable (< 500 cfu/ml) they
are determined to be in compliance with the requirement for a detectable residual in the
distribution system. Will these systems now be required to measure a chlorine residual to
ensure they do not exceed the MRDL?
Yes. The Stage 1 DBPR requires that disinfection residuals be measured to ensure the MRDL is
not exceeded. Therefore, HPC measurements cannot be performed in lieu of this testing.
However, where detectable residuals are not found, HPCs may be conducted for SWTR
compliance.
     Q:  Our state requires daily chlorine residual measurements to be taken throughout the distribution
         system. What samples should be considered when calculating compliance with the MRDL?
     A:  For the Stage 1 DBPR's MRDL, compliance is based upon the samples collected under
         141.132(c)(l). The samples are collected at the same time and place as coliform samples as
         specified in 141.21. Subpart H systems may use samples collected under the requirements of the
         SWTR ( 141.74(c)(3)(i)) in lieu of taking separate samples. The system's monitoring plan will
         indicate which samples are to be used for compliance determinations.


     Q:  Can systems use additional chlorine sampling sites (if states have approved additional sites
         beyond the TCR)?
     A:  Yes, if these are included in the monitoring plan.


     Q:  Does the Stage 1 DBPR apply to chlorine added to the treatment process as an oxidant?
     A:  Yes. The requirements are applicable to chlorine added anywhere in the treatment process due to
         the potential formation of TTHM and HAAS.
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     Q:  For a system to comply with the MRDLs for chlorine and chloramine, what residual
         disinfectant concentration should be measured?
     A:  For a system that uses free chlorine for residual maintenance, either free or total chlorine
         measurement is acceptable. For a system that uses chloramines for residual maintenance, the
         measure must be combined or total chlorine.


        1.1.2   Chlorine Dioxide

               For further information, see the following rule sections:
Citation
141.32(e)(78)(i),(ii)
141.201
141.54
141.65
141.131(c)(l),(2)J(3)
141.132(c)(2Xi),(ii)J(iii)
141.133(c)(2)(i),(ii)
141.134(c)
Part Title
Public Notification
Public Notification of Drinking Water Violations
Maximum Residual Disinfectant Level Goals
Maximum Residual Disinfectant Levels
Analytical Requirements
Monitoring Requirements
Compliance Requirements
Reporting and Recordkeeping Requirements
               Does daily monitoring for chlorine dioxide mean 7 days a week? Some systems are not
               staffed on the weekend. Do systems that add chlorine dioxide need to have someone in on
               the weekend in order to stay in compliance?
               Yes, systems will have to conduct this monitoring daily. Systems have 3 or 5 years,
               depending on source water type and size, to get the plant staffed for conducting the
               required monitoring or change the disinfectant. This monitoring is required and must be
               conducted daily due to the acute health risks associated with chlorine dioxide.
        Q:     What systems are required to monitor for chlorine dioxide and chlorite?
        A:     All nontransient noncommunity and community systems that use chlorine dioxide,
               regardless of the purpose, (e.g., disinfection, oxidation, or maintenance of a residual) must
               monitor for both chlorine dioxide and for the disinfection byproduct, chlorite. Transient
               noncommunity  systems that use chlorine dioxide must monitor for chlorine dioxide, but not
               for chlorite. There is no provision under the rule for reduced chlorine dioxide monitoring
               even if the chlorine dioxide is not used for primary disinfection. If the system is using
               chlorine dioxide intermittently, the system is not required to conduct the daily monitoring
               for chlorine dioxide  and chlorite for days when the chlorine dioxide is not in use or monthly
               monitoring for chlorite if the chlorine dioxide has not been used at all for the entire month.
               Monthly monitoring for chlorite is required if chorine dioxide is used at any time during the
               month.
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       Q:     If my system is triggered into repeat CIO2 sampling and I have booster chlorination, the
               rule says one of the repeat samples must be "as close to the first customer as possible. "
               Does this mean the first customer in the entire distribution system, or the first customer
               after booster chlorination?
       A:     The term "first customer" refers to the first customer in the distribution system. However,
               the sample that is taken at the longest residence time for compliance with C1O2 monitoring
               requirements at 141.132(c)(2)(ii) should be downstream of the point of booster
               chlorination.


1.2    Disinfection Byproducts

       1.2.1   TTHM and HAAS

               For further information, see the following rule sections:
Citation
141.32(eX79)
141.201
141.53
141.64
141.131(b)(l),(2)
141.132(b)(lXi),(ii)J(iii),(iv)
141.133(bXlXiX(iiX(iii)
141.134(b)
Part Title
Public Notification
Public Notification of Drinking Water Violations
Maximum Contaminant Level Goals
Maximum Contaminant Levels
Analytical Requirements
Monitoring Requirements
Compliance Requirements
Reporting and Recordkeeping Requirements
       Q:     If a system rechlorinates in the distribution system, are these rechlorination stations
               considered "separateplants" under the Stage 1 D/DBPR?
       A:     No, these rechlorination stations are not generally considered separate plants for minimum
               monitoring determinations. However, they should be taken into consideration when
               developing monitoring plans so that maximum residence time/maximum DBF formation is
               seen, and depending upon the specifics of the system the state may wish to consider these
               stations as "separate plants".


       Q:     The TTHM Rule requires systems to take all required samples within a 24-hour period.
               The Stage 1 Rule, however, does not specify a time-frame when all the samples need to be
               collected. When should systems take their required TTHM/HAA5 samples?
       A:     EPA believes that most systems will find it advantageous to take all their samples in one
               day but this is not required by the Stage 1 DBPR. However, states may require systems to
               collect all their TTHM/HAA5 samples within a specified period of time. In either case,
               systems must specify when their TTHM/HAA5 samples will be taken in their monitoring
               plan.
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       Q:     With respect to the new compliance requirements for TTHM testing that take effect in
               2002 (or 2004 for small systems), when the new TTHMMCL comes into effect, will
               compliance be calculated based on the samples collected in the 2001  (or 2003) calendar
               year? Or, are they calculated based on the samples collected during the 2002 (or 2004)
               calendar year? At what point does the waterworks go out of compliance between the
               annual average of 0.100 mg/L and 0.080 mg/L?
       A:     Compliance with the new MCL is based on samples taken beginning in the  first quarter of
               2002/2004. During the first year of compliance calculation if the sum of fewer than four
               quarters of data exceeds 0.320mg/L for TTHM or 0.240mg/L for HAAS, the system is
               immediately in violation (since they will exceed the MCL even if the remaining quarters are
               zero).


       Q:     Can you be on routine monitoring for TTHMs and reduced monitoring for HAA5, or vice
               versa?
       A:     No, a system cannot qualify for reduced monitoring for one contaminant and not for the
               other.


       Q:     Will systems currently on reduced TTHM monitoring for the 1979 TTHM Rule be able to
               remain on reduced monitoring under the Stage 1 DBPR?
       A:     Unless these systems conducted  TTHM/HAA5 monitoring under the ICR,  and have
               qualified with those  samples, they will have to revert to routine monitoring under the Stage
               1 DBPR until they re-qualify for reduced monitoring. Systems must have an annual
               average less than or equal to 0.040 mg/L and 0.030 mg/L for TTHM and HAAS
               respectively before they can qualify for reduced monitoring.


       Q:     To qualify for reduced TTHM and HAAS monitoring, a Subpart H system  must have one
               year of source water TOC data.  To remain on reduced monitoring does the system  need
               to have TOC data (i.e., is this a one time average  or a rolling average)?
       A:     To qualify for reduced TTHM and HAAS monitoring, a Subpart H system  must have one
               year of source water TOC data with an annual average no more than 4.0 mg/L prior to
               treatment. To remain on reduced monitoring the Subpart H system's annual average TOC
               level, before any treatment, must be less than or equal to 4.0 mg/L TOC. This is based on
               a rolling annual average and is not a one-time test. If a plant does not use conventional
               treatment, it is not required to monitor monthly for TOC for the enhanced coagulation
               requirement. However, if it wants to qualify for, and remain on, reduced monitoring for
               TTHM and HAAS, it must monitor monthly for TOC before any treatment.


       Q:     Will states and systems need to adjust their monitoring and compliance activities based
               on the quarters created by the publication date of the rules on December  16? (i.e.,  will
               states and systems be allowed to start the new quarter on January I rather than
               December 16?)
       A:     This issue was addressed with a technical correction to the rule published in the Federal
               Register on January 16, 2001. Monitoring and compliance activities will take effect
               beginning on January 1 following the December 16 compliance  dates in the rule as
               published on December 16,  1998.
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       Q:     Please clarify compliance dates for monitoring under this rule. The rule states that the
               systems must comply with the rule requirements beginning January I, 2002, or 2004
               depending on the system size and source.  What is the definition of beginning? Does this
               mean that systems must conduct their monitoring for TTHM and HAA5 a year in advance
               to determine compliance on December 16, 2001 (or 2003)? Or, do they start the
               monitoring in the first quarter of 2002 (or 2004) to determine compliance after the fourth
               quarter of 2002 (or 2004)?
       A:     Monitoring begins in first quarter 2002/2004, with compliance determined after the fourth
               quarter, if quarterly samples are required. If the TTHM and HAAS results are less than or
               equal to 0.080 mg/L or 0.060 mg/L respectively, the PWS is in compliance. If the results
               are greater than 0.080 mg/L or 0.060 mg/L for systems monitoring annually (or  less
               frequently), the system goes to increased (quarterly) monitoring.


       Q:     Can states phase out the TTHM rule faster than the DBPR  allows?
       A:     Yes, but only if states adopt and implement the Stage 1 DBPR ahead of schedule.


       Q:     Can samples be taken for operational purposes and not be used for compliance?
       A:     Yes. Systems are encouraged to take operational samples as necessary. Operational
               samples do not have to be used for compliance; however all samples used for compliance
               purposes must be noted in the system's monitoring plan.


       Q:     Under the Stage 1 DBPR, if a system must increase its chlorine or chloramine levels to
               address an emergency (e.g. a main break or other contamination event), and is scheduled
               to collect DBF samples, should the system reschedule its TTHM/HAA5 sampling?
       A:     The system is required to monitor during normal operating conditions, this includes changes
               in disinfection levels caused by water quality fluctuations. However, if the system is
               experiencing an emergency, and must increase its chlorine or chloramine levels during the
               period that monitoring is required under the sampling schedule, the system must consult
               with the state to determine if sampling may be delayed until the emergency has ended, and
               normal operation is resumed.


       Q:     How can  systems with more  than one treatment plant determine compliance if each plant
               provides a different percentage of the system 's supply? Averaging of all of the  samples
               taken from a surface water source providing 90% of the systems water and a ground
               water plant serving the other 10% may not truly reflect the level ofTTHMs and HAAS in
               the entire system.
       A:     EPA believes that for systems with more than one treatment plant, the quarterly average,
               representative of each treatment plant, should be determined separately. The quarterly
               average for the entire system should be calculated by weighing the averages for  each of the
               treatment plants (total number of treatment plants = n) as follows:
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                      (Quarterly average for samples representing treatment plant 1)
                      X (fraction of flow*into system from plant 1)


                       +    (Quarterly average for samples representing treatment plant 2)
                            X (fraction of flow* into system from plant 2)


                       + ...  (Quarterly average for samples representing treatment plant n)
                            X (fraction of flow* into system from plant n)


                      = quarterly average for the system


               * for the purposes of this determination only, flow is defined as the average daily flow for
               the subject treatment plant during the subject compliance period.
               (Note: this formula is taken directly page 13 of EPA's 1983 Guidance titled:
               Trihalomethanes in Drinking Water - Sampling, Analysis, Monitoring, and Compliance).
               For added explanation, we offer the following based on the above formula:
                      Plant 1  serves 90% of the water to the system and has a quarterly average of 120
                      ppb for TTHM and plant 2 serves the other 10% and has a quarterly average of 40
                      ppb for TTHM or (120 X 0.9) + (40 X 0.1) = 112 ppb as  a quarterly average for
                      the system.


        Q:     Assume a system has multiple wells and a single surface water source. Are the TTHM and
               HAAS monitoring requirements for each plant, ground water and surface water, based
               upon the  requirements for Subpart H systems?
        A:     Yes. A system that uses ground water as well as surface water or ground water under the
               influence of surface  water as part of their source is considered a Subpart H system. The
               monitoring requirements for all plants are  as established in the rule for Subpart H systems.
               See also Section IV-G: Determining Monitoring Frequency for TTHM and HAAS
               Sampling, Mixed Sources (Surface Water and Ground Water), Example SG3.


        Q:     If a Subpart H system serving greater than or equal to 10,000 persons has two treatment
               plants and the distribution system is configured in such a way that one of the samples
               (e.g., max residence time) is in effectively the same location for both plants can the
               system use one sample to cover both treatment plants or does the  system have to take two
               samples? In the most simple example, can the system take 7 samples instead of 8 with one
               sample counting for two?
        A:     If a system can demonstrate in its monitoring plan to the satisfaction of the state that a
               sample taken within the distribution system effectively covers the monitoring requirements
               for two plants, it could count one sample as meeting the intent of the regulation. States
               should be reviewing the sampling plan to determine if by not taking a  sample the system
               will still have data reflective of the spacial and temporal conditions in the distribution
               system for byproduct formation. However, this would not be considered appropriate for
               systems which are only required to take samples at one location per plant.
Stage 1 DBPR FAQs                                                                         Page 10

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       Q:     If a system uses surface water to supplement its ground water source on a seasonal basis
               what kind of system is it, Subpart H or ground water? What is the routine monitoring
               frequency for TTHM and HAA5 and how does the system qualify for reduced monitoring?
       A:     The system would monitor according to the subpart H requirements during any quarter
               when using either surface water or ground water under the influence of surface water, the
               sample shall be taken so the results are representative of the surface source. When only
               using ground water, the system would monitor according to the requirements for a ground
               water system. (See the table under 141.132) The compliance calculations are based on a
               running annual  average computed quarterly. If the running annual average computed
               quarterly for TTHM and HAAS is  less than or equal to 0.040 mg/L and 0.030 mg/L,
               respectively, and meets the TOC levels required for the months that the system uses
               surface water, the system qualifies  for reduced monitoring.
               See also Section IV-G: Determining Monitoring Frequency for TTHM and HAAS
               Sampling, Mixed Sources (Surface Water and Ground Water), Example SG4.


       Q:     How does a system determine its month of warmest water temperature for the purposes of
               monitoring for  TTHM and HAA 5 on a yearly or less frequent basis under the Stage I
               DBPR?
       A:     Systems should monitor the temperature of their treated water or  use historical data to
               ensure they are  collecting samples  during the month of warmest water temperatures (i.e.
               when disinfection byproduct formation is accelerated). For most systems this is likely to
               occur in July, August, or September. If the system operates during these months, this
               would likely be the time to take the TTHM and HAAS samples. Systems that do not
               operate during these months must take their samples  during the warmest month in which
               they operate. This requirement is designed to allow less frequent monitoring by collecting
               samples during  worst case conditions.


       Q:     Why  are the levels of TTHM and HAA5 established at lower concentrations to qualify for
               reduced monitoring than to stay on reduced monitoring once qualified?
       A:     Routine monitoring for TTHMs and HAAS gives an indication of "average" disinfection
               byproduct occurrence in the distribution system. On the other hand, sampling requirements
               for reduced monitoring are designed to ensure that the sample measures "worst case"
               conditions for occurrence of the disinfection byproducts. Thus, these worst case samples
               are expected to  contain higher concentrations of DBFs than the average of routine  samples.

       Q:     If a system is conducting routine yearly monitoring for TTHM/HAA5 and exceeds the
               MCL for either DBF in this yearly sample, is the system in violation under the Stage 1
               DBPR?
       A:     The system is not immediately in violation. The system must increase their monitoring to
               quarterly the very next quarter. If after a year of quarterly monitoring the system exceeds
               the MCL  as an  annual average, the system is in violation. If the system fails to perform all
               of the quarterly monitoring, compliance will be determined based on the available data and
               the system will  also have a monitoring violation.


       Q:     If the system uses an ICR approved lab to do the testing for TTHM and HAA 5 in the first
               year, can  it use the data collected to qualify for reduced TTHM  and HAA 5 monitoring?
       A:     If the state approves the lab, then the system can use the data to qualify for reduced
               TTHM and HAAS monitoring provided that the data meets all the other D/DBPR
               compliance sampling and analysis requirements. In addition,  Subpart H systems must meet
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               applicable TOC levels. Systems which collected TTHM and HAAS data for applicability
               monitoring under the IESWTR (see Q and A in section 2.2) can use that data if the samples
               were analyzed by a certified laboratory using approved ICR methods.


       Q:     Do TTHM and HAA5 samples have to be collected at the same time and location?
       A:     Yes, they should. However, there is no regulatory requirement to sample at the same time
               and location. The system has to specify locations and schedules for collecting samples in
               its monitoring plan.


       Q:     Does the use of any oxidant mean that my system is required to sample for TTHMs?
       A:     A system that uses an oxidant that can also be used as a disinfectant (such as C1O2 or O3)
               must sample for TTHMs. However, a ground water system that uses an oxidant that is
               NOT a disinfectant (such as KMnO4  for taste and odor oxidation) and does not add another
               disinfectant to their water, is not required to monitor for TTHMs.


       Q:     Do systems  that only add ozone have to monitor for TTHM and HAA 5?
       A:     Yes, all systems that supply water treated with a chemical disinfectant are required to
               monitor for TTHM and HAAS.
       1.2.2   Bromate

               For further information, see the following rule sections:
       Q:

       A:
Citation
141.32(eX80)
141.201
141.53
141.64
141.131(b)(l),(2)
141.132(b)(3)(i),(ii)
141.133(b)(2)
141.134(b)
Part Title
Public Notification
Public Notification of Drinking Water Violations
Maximum Contaminant Level Goals
Maximum Contaminant Levels
Analytical Requirements
Monitoring Requirements
Compliance Requirements
Reporting and Recordkeeping Requirements
May bromate monitoring be modified for systems based on the population served (as
TTHM and HAA5 monitoring is structured)?
No, there are no provisions in the Stage 1 DBPR to monitor for bromate based on system
type and/or size.
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       Q:     Do systems using low levels of ozone at the beginning of the plant for purposes of
               enhancing filtration need to test for bromate under this rule?
       A:     Yes. The rule specifies that any community or nontransient noncommunity system that
               uses ozone, for disinfection or oxidation, must take one bromate sample per month per
               treatment plant using ozone at the entrance to the distribution system. (See 141.132(b)(3))
        1.2.3   Chlorite

               For further information, see the following rule sections:
       Q:

       A:
Citation
141.32(eX81)
141.201
141.53
141.64
141.131(b)(l),(2)
141.132(b)(2)(i),(ii)
141.133(b)(3)
141.134(b)
Part Title
Public Notification
Public Notification of Drinking Water Violations
Maximum Contaminant Level Goals
Maximum Contaminant Levels
Analytical Requirements
Monitoring Requirements
Compliance Requirements
Reporting and Recordkeeping Requirements
May chlorite monitoring be modified for systems based on the population served (as
TTHMandHAA5 monitoring is structured)?
No, there are no provisions in the Stage 1 DBPR to monitor for chlorite based on system
type and/or size.
       Q:     Daily monitoring means 7 days a week. Some systems are not staffed on the weekend. Do
               systems that add chlorine dioxide need to have someone in on the weekend in order to
               stay in compliance?
       A:     Yes, systems required to conduct daily monitoring under the Stage 1 DBPR will have to
               conduct this monitoring daily. The system has 3 or 5 years, depending on its source water
               type and size, to get the plant staffed for conducting the required monitoring or change their
               disinfectant. This monitoring is required and must be conducted daily due to the acute
               health risks associated with chlorine dioxide.


       Q:     Can you use analytical methods other than those listed in the Federal Register?
       A:     The methods in the rule must be used.


       Q:     When we have to do additional sampling because of an exceedence of 1.0 mg/L chlorite
               at the entrance to the distribution system, say 1.5 mg/L, and chlorite in the  distribution is
               less than that level, can we assume that if the level at the entrance to the distribution
               system is 1.2 mg/L, the level in the distribution will be lower and forego monitoring?
       A:     If the system exceeds 1.0 mg/L, the system MUST conduct the additional monitoring (3
               samples in the distribution system) the following day.
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        Q:     Do the MCL and monitoring requirements for chlorite apply to transient systems that use
               chlorine dioxide?
        A:     The MCL and monitoring requirements for chlorite apply only to community and
               nontransient noncommunity systems that use chlorine dioxide.  Chlorite is not regulated for
               transient systems.


        Q:     Does EPA intend for daily chlorite samples to be sent out to a certified laboratory for
               analysis or could systems do hand held testing at the entrance to the distribution system
               for chlorite?
        A:     The original rule requires that the analysis be performed by a certified laboratory, however,
               EPA updated the rule through technical corrections published in the Federal Register on
               January 16, 2001 to allow daily chlorite sampling and analysis to be performed by a party
               approved by the state.
1.3     Disinfection Byproduct Precursors

        For further information, see the following rule sections:
        Q:

        A:
Citation
141.32(e)(79)
141.201
141.131(dXl),(2),(3),(4),(5)
141.132(dXl),(2)
141.133(d)
141.134(d)
141.135 [entire part]
Part Title
Public Notification
Public Notification of Drinking Water Violations
Analytical Requirements
Monitoring Requirements
Compliance Requirements
Reporting and Recordkeeping Requirements
Treatment Technique for Control of DBF Precursors
Do lime softening plants need to consider alternative compliance criteria and/or Step 1
TOC removal requirements or can they go right to the Step 2 bench-scale testing?
EPA believes that all lime softening plants will meet at least one of the alternative
compliance criteria, one of the additional alternative compliance criteria for softening plants,
or will be able to achieve step 1  TOC removal requirements. The Step 2 bench testing
procedures are not designed for softening systems since the step 2 procedure is designed to
lower pH while the softening process raises pH. Thus Step 2 does not apply to softening
systems.
        Q:     Some treatment plants operate seasonally. How do you determine quarterly averages?
        A:     These systems must use the average of the available data in each quarter the plant operates.


        Q:     Would you ever end up with a treated water TOC higher than an untreated source water
               TOC?
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       A:     This may happen as a result of the analytical methods used to measure TOC where minor
               variations (measurement error) may show a treated water TOC slightly higher than a source
               water TOC level.


       Q:     When the treated water TOC level is greater than the untreated water TOC level, what
               number should be used in the monthly calculation?
       A:     There are two ways to calculate compliance with the Step 1  TOC removal requirements.
               The first is to calculate the actual percentage of TOC removal from the source and treated
               waters for that month [141.135(c)(l)(i)]. In  any month where the treated water TOC level
               is greater than the source water TOC level, the monthly calculation would be a negative
               number. Second, the system could use an alternative compliance calculation method. For
               example, if the system's treated or source water TOC is less than 2.0 mg/L  the system
               would assign the value of 1.0 for that month. For any month that a system practicing
               softening removes at least 10 mg/L of hardness (as CaCOs)  the system would assign the
               value of 1.0 for that month [141.135(c)(2)(i)].


       Q:     Does the addition of a disinfectant affect where and when source water TOC sampling is
               performed?
       A:     Yes, TOC monitoring must occur before any disinfectant is  added into the system.


       Q:     If a system meets one of the alternative compliance criteria is it exempted from
               implementing enhanced coagulation?
       A:     If a system meets one of the alternative compliance criteria as a running annual average,
               calculated quarterly, they are in compliance with the precursor removal treatment technique
               and do not have meet the Step 1 TOC removal requirements. For those systems that must
               implement enhanced coagulation or enhanced softening, alternative compliance criteria can
               also be used  for compliance calculations on  a month-by-month basis. (See  141.135(c)(2))


       Q:     If a system has met the same alternative compliance criterion for the past four quarters
               does this mean it is in compliance for the previous year or for the following year?
       A:     This system is in compliance for the previous year.


       Q:     Does a system always have to use the same alternative compliance criterion to avoid
               employing enhanced coagulation?
       A:     In order to avoid employing enhanced coagulation, the system must meet the same
               alternative compliance criterion for the past four quarters to calculate a running annual
               average. If it cannot meet this same criterion for four quarters, the system is required to
               perform enhanced coagulation and perform the compliance calculations required in
               141.135(c). However, once a system is required to employ enhanced coagulation, they
               may employ  alternative  compliance criteria on a month-by-month basis (141.135(c)(2)(i)-
               (v)) in lieu of performing the calculations in 141.135(c)(l).  Alternative compliance
               criteria used  on a month-by-month basis for calculating compliance can change depending
               on the time of year and  the characteristics of the water.
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       Q:     If I meet an alternative compliance criterion for the month and have exceeded the Step 1
              removal requirements, should I use 1.0 or the calculated number in my compliance
              calculations?
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       A:      You should use the calculated number, since if you exceed the Step 1 removal
               requirements, this number will be greater than 1.0. This number will "help" the quarterly
               average you calculate assuming you have a month where your TOC percent removal ratio
               is less than 1.0.
       Q:      Does the state need to approve all TOC percent removal levels under the Stage I DBPR?
       A:      The state is only required to approve the Step  2 removal levels, not the Step 1 TOC
               removal levels.


       Q:      What should a conventional softening system  do if it must meet the TOC removal
               requirements under the Stage I DBPR by dropping alkalinity and then must recarbonate
               to adjust pH and alkalinity for achieving compliance with the Lead and Copper Rule?
       A:      The system may use either the TOC percentage removal requirement or the alternative
               compliance criteria (less than 60 mg/L (as CaCO3) to comply with the rule. The system
               may then recarbonate to comply with the Lead and Copper Rule.  Treated water alkalinity,
               for purposes of compliance with the Stage 1 DBPR, should be measured prior to
               recarbonation  and may be measured anywhere in the treatment plant.


       Q:      Do labs have to be certified to conduct TOC monitoring?
       A:      A system must use a party approved by EPA or the state to measure TOC, with any of the
               methods specified in the regulations. Use of a certified laboratory  is not required.


       Q:      Is GAC effective in removing DBFs? May it be used by conventional plants in lieu of the
               treatment technique for DBF precursor removal under the Stage I DBPR?
       A:      The system may use GAC  if it provides adequate TOC removal to allow the system to
               meet either Step 1 or one of the alternative compliance criteria for finished water.  GAC is
               effective depending on the type of carbon used, the contact time,  and the nature of the
               DBPs. Depending on the type of carbon used, it can also be expensive and cause
               operational and disposal problems. EPA recommends that systems not use GAC  for
               removal of DBPs after flocculation but instead use it for DBP precursor (TOC) removal, if
               necessary. GAC can be used to "enhance" enhanced coagulation and TOC removal in
               conventional plants. However, because GAC tends to work most effectively when used in
               tandem with enhanced coagulation rather than  in lieu of, it is not normally a substitute for
               DBP precursor removal.


       Q:      How often  does a system doing Step 2 have to perform bench- or pilot-scale testing?
       A:      The rule only requires that it be performed; the frequency is determined by the state. In the
               EPA guidance on Enhanced Coagulation, the recommended frequency for the Step 2
               bench- or pilot-scale testing is at least quarterly for the first year. If source water quality
               changes significantly on a more frequent basis, Step 2 testing may need to be conducted
               more frequently. The minimum levels of TOC removal will be determined by this testing
               and established as regulatory requirements by the state.
               The guidance manual (EPA 815-R-99-012) is available at EPA's website:
               www.epa.gov/safewater/mdbp/implement.html or fromNSCEP at 1.800.490.9198.


       Q:      Why are enhanced coagulation and enhanced softening only required at conventional
               plants?
       A:      Enhanced coagulation and enhanced softening  involve the addition of higher levels of
               coagulants  (i.e., higher than is required for turbidity removal). Therefore, a sedimentation

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               (solids removal) process is necessary to remove solids prior to filtration. Without
               sedimentation, the solids would plug the filters, and result in short filter runs and poor
               operation. In the Stage 1 DBPR, the precursor removal requirements apply to those
               systems best able to remove DBF precursors at relatively low cost.


        Q:     Do you change Step 2 TOC removal requirements when there is a routine seasonal
               change in source water quality?
        A:     The frequency of the Step 2 bench- or pilot-scale testing is determined by the state. In the
               EPA guidance on Enhanced Coagulation, the recommended frequency for the Step 2
               bench- or pilot-scale testing is at least quarterly for the first year. If source water quality
               changes significantly on a more frequent basis, Step 2 testing may need to be conducted
               more frequently. The minimum levels of TOC removal will be determined by this testing
               and established as regulatory requirements by the state. In addition, it may vary on a
               seasonal basis if approved by the state.
               The EPA guidance manual  (EPA 815-R-99-012) is available at
               www.epa.gov/safewater/mdpb/implement.html or fromNSCEP at 1.800.490.9198


        Q:     For the  "simultaneous " paired sample, what is the time-lag allowed between samples
               (accounting for detention time)?
        A:     The rule requires the paired samples to be collected "at the same time." In practice EPA
               expects that systems will typically collect the source water sample followed, in a few
               minutes to a few hours, by  the treated water sample. In situations where raw water  quality
               fluctuates frequently, the system may need to provide a time-lag between the samples equal
               to the residence time of the water between sampling points. This will ensure the samples
               accurately reflect the actual TOC removal. In all cases systems should address their
               sampling procedure in their monitoring plans.
        Q:     If a system treats blended water from two very different source waters (one source meets
               an alternative compliance criterion, the second source does not) may the system forego
               enhanced coagulation?
        A:     The enhanced coagulation/enhanced softening requirements are based on the source water
               TOC and alkalinity. All measurements and compliance determinations must be made on the
               water that is actually treated in the plant under normal operating conditions. If that water is
               comprised of a blend from multiple sources, the composition of the blend will determine
               whether alternative compliance criteria are met or whether achieving the minimum TOC
               removal requirements of enhanced coagulation is necessary.


        Q:     What if for one month water is not amenable to enhanced coagulation?
        A:     Compliance is based on a running annual average. The system may elect to use the
               calculated data, use an alternative compliance criterion (if possible) that month, or apply for
               a Step 2 removal requirement for the month.
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       Q:     If a system is unable to meet any alternative compliance criteria or Step 1 TOC removal
               requirements in the first quarter of monitoring, can it decide to go to Step 2 immediately,
               rather than waiting for the full year of data collection?
       A:     The system may elect to conduct the necessary bench-scale testing immediately but
               because compliance is based on a running annual average, the system is not eligible for Step
               2 removal until one year of data have been collected.


       Q:     If a system, through excessive lime softening, lowers the alkalinity to below 60 mg/L
               and/or removes at least 10 mg/L of magnesium hardness and, therefore, meets one or
               more of the compliance criteria, why does it need to do the  TOC monitoring? Do states
               have the flexibility to allow such systems to forego TOC monitoring?
       A:     States do  not have the flexibility to allow systems to forego TOC monitoring. EPA believes
               that systems may not always meet one of the alternative compliance criteria, and that the
               system needs to have the data in such cases to determine compliance. Additionally, in order
               to qualify for, and remain on, reduced monitoring for TTHM and HAAS these Subpart H
               systems must continue to perform monthly TOC monitoring  of untreated source water.


       Q:     If a softening system wishes to use the additional alternative compliance criteria for
               softening systems and its jar-testing demonstrates a finished water alkalinity below  60
               mg/L, but samples in the plant that incorporate the prescribed coagulant dose still exceed
               60 mg/L,  is the system in compliance with the Step 2 requirements?
       A:     There are no Step 2 provisions for softening systems. The alkalinity or magnesium
               hardness removal levels must be met in the full-scale plant. For non-softening systems,
               Step 2 determines a removal requirement, not a coagulant dose requirement.


       Q:     How should the state deal with the situation  where the full-scale results do not achieve
               the required step 2 TOC removals predicted by jar testing?
       A:     Failure to meet step 2 TOC removal requirements results  in a violation. The system should
               be encouraged to experiment with acids, alternative coagulants, etc. to improve TOC
               removal and ensure compliance.


       Q:     May a system grandfather Step 2 jar testing results in advance  of the effective date of the
               Stage 1 D/DBPR requirements provided that the system  meets all the  technical criteria
               specified in the rule?
       A:     To meet the special primacy requirements, the state has to develop Step 2 methodology. If
               a system wishes to begin testing early, the system should ensure that the state has
               submitted its Step 2 methodology to EPA for approval.


       Q:     If there is a group of surface water intakes close to each other,  can they do one raw water
               TOC sample?
       A:     No, Because the TOC levels in surface water can vary greatly by time and location in a
               water body. Plants are required to take TOC samples at each intake, because the samples
               must reflect the treated water samples.
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       Q:     Section 141.135(b)(3) says that once the state approves a Step 2 TOC removal
               percentage, the state may make that percentage retroactive. However, Section I4l.l33(d)
               says that systems which do not meet the Step I requirements during the first 12 months
               are not eligible for retroactive approval of Step 2 requirements. Which is correct?
       A:     Both are correct. Section 141.133(d) limits what may be done in the first year for a system
               which elects to enter the compliance period uninformed. Systems may begin monitoring in
               2001/2003 to determine whether Step 1 levels can be met. This monitoring is not
               mandatory and failure to monitor during the 12 months prior to the compliance date is not a
               violation. However, failure to conduct this monitoring makes a system ineligible for
               retroactive approval of a step 2 alternative TOC removal level during 2002/2004. After
               2002/2004, all systems are eligible for retroactive step 2 approval, whether the early
               monitoring was conducted or not. The M-DBP FACA negotiating committee and EPA
               believed that systems should not be allowed to claim ignorance of whether compliance had
               been achieved, but also recognized that future changes in source water quality may affect a
               system's ability to achieve compliance. To balance these two, the rule allows for retroactive
               approval of Step 2 criteria if the system has data that indicates that the system has taken
               prudent measures to comply. Failure to  determine compliance status is not prudent. Such
               retroactive approval is not available for MCL compliance or for compliance with other
               treatment techniques.


       Q:     How does a system that is treating for zebra mussel control by injecting chlorine at the
               intake collect untreated source water samples for TOC?
       A:     The system may have to discontinue its chlorine feed for a brief period in order to  collect
               the sample. Alternatively,  the state may allow a grab sample at the entrance to the intake to
               the plant before any treatment. This  situation should be addressed in the system's
               monitoring plan.


       Q:     TOC measurements are limited to two significant figures.  The use of these values in
               compliance calculations under 141.135(c) cannot produce a value with a greater
               number of significant figures.  However, systems are required to compare the value
               calculated for compliance to 1.00 which has three significant figures. How do you
               reconcile this?
       A:     The increase in significant figures was an oversight by EPA. The intent was for systems to
               compare the calculated value at two  decimal places.


1.4    Monitoring

       1.4.1   General Monitoring Issues


       Q:     How do you determine TOC levels to qualify for or remain on reduced monitoring for
               TTHM and HAA 5 if you have multiple treatment plants? Can you have reduced
               monitoring for one plant and not another? Or should all the plants be treated the same?
       A:     Systems cannot be on reduced monitoring for TTHM and HAAS at one of their plants  and
               routine monitoring for another because compliance is based on the TTHM and HAAS
               levels for the entire system.  Each plant's source water TOC level must be less than or
               equal to 4.0 mg/L.
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        Q:     If you have both ground water and surface water the system is considered to be a Subpart
               H system. As a Subpart H system,  is it required to follow the monitoring for Subpart H
               systems for all of their treatment plants including ground water plants?
        A:     Yes. If the system is a Subpart H system the monitoring requirements for Subpart H
               systems apply to all plants whether ground water or surface water.


        Q:     How does a system (either ground water or surface water) determine the month of
               warmest water temperature, when there is little or no temperature variability?
        A:     To meet this requirement systems should regularly monitor their source and distribution
               water temperatures or use historical data. In cases where the water temperature is very
               constant, the system may consult with the state regarding the proper month in which to
               conduct sampling. The results  of this consultation would then be incorporated into the
               system's monitoring plan. The state may also be able to better spread out the monitoring to
               avoid lab capacity issues.
        1.4.2   Monitoring Plans

               For further information, see the following rule sections:
        Q:
        A:
Citation
141.132(aXl),(2)5(3)
141.132(f)(l),(2);(3)
Part Title
Monitoring Requirements (General requirements)
Monitoring Requirements (Monitoring plans)
Under the Stage I DBPR, when does the monitoring plan need to be completed?
The monitoring plan must be complete and available for inspection by the state and public
no later than 30 days following the applicable compliance dates in   141.130(b). Subpart H
systems > 3,300 must submit their monitoring plans with their first monitoring report.
        Q:     Do all monitoring plans have to be reviewed and approved by the state to ensure the
               system is planning monitoring that will achieve compliance in all areas of the Stage 1
               DBPR?
        A:     States are encouraged to review or approve monitoring plans. States will generally check
               the monitoring plans during the sanitary surveys or other visits. Subpart H systems serving
               >3,300 must submit monitoring plans to the state  for review. States may require plans to be
               submitted by any other system and may require changes to the plan.


        Q:     How should a system determine residence times and conduct monitoring under the
               Stage I DBPR if it has a complicated distribution system?
        A:     This should be addressed in the monitoring plan for the system and should be reviewed by
               the state to ensure the system will be in compliance. In the monitoring plan, the system
               should indicate why samples are being taken in a particular location. EPA intends for sites
               to be generally selected based on best professional judgement rather than on computer
               analyses and tracer studies.
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       Q:     Is there a restriction on how often a system can revise their monitoring plan?
       A:     The frequency of allowable modifications to the monitoring plan is not addressed in the
               rule. Clearly changes in sources, disinfectants, etc. will make modifications necessary and
               sometimes unpredictable. EPA believes this is best left up to states' discretion. Any time a
               Subpart H  system serving greater than 3,300 people modifies its sampling plan, the system
               must submit this modified sampling plan to the state.
        1.4.3   Multiple Wells Drawing from a Single Aquifer

               For further information, see the following rule sections:
       Q:

       A:
Citation
141.132(a)(2)
Part Title
Monitoring Requirements (General requirements)
If a system has multiple wells drawing from the same aquifer, what is the monitoring
frequency for TTHM and HAA5?
The wells may be treated as one plant for the purposes of determining monitoring
frequency for TTHM and HAAS. This is true even if each well or some of the wells have
their own treatment.
       Q:     If a system has one treatment plant with multiple wells from different aquifers, how is the
               monitoring frequency determined?
       A:     If all the sources are combined into a single treatment plant, the number of samples
               required for that plant is determined by system size.


       1.4.4   Reporting and Recordkeeping

               For further information, see the following rule sections:
Citation
141.134(b)&(c)
Part Title
Reporting and Recordkeeping Requirements
               Section 141.134, reporting and recordkeeping requirements for TTHM/HAA5, chlorite,
               bromate, chloramines and chlorine, requires systems to report "whether the MCL (or
               MRDL) was exceeded. "  The requirements for systems monitoring for chlorine dioxide,
               on the other hand, are to report "whether the MRDL was exceeded" and "whether the
               MRDL was exceeded in any two consecutive daily samples and whether the resulting
               violation was acute or chronic. " Does the requirement to report "whether the MCL (or
               MRDL) was exceeded, " mean the system should report any single sample that exceeds the
               MCL (or MRDL) or only report exceedences that result in violations?
               For each compliance period, Systems are required to report results of all samples whether
               or not they exceed the MCL or MRDL, they are also required to report any violations of
               the MCL or MRDL, based upon the compliance determination for the monitoring period
               for which they are reporting.
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       1.4.5   Consecutive Systems

               For further information, see the following rule sections:
       Q:

       A:
Citation
141.132(f)(3)
Part Title
Monitoring Requirements (Monitoring plans)
Will a wholesale system be required to change its treatment process if there is an MCL or
MRDL exceedence in system that purchases its water?
Each system is responsible for achieving and maintaining compliance. In most cases EPA
expects wholesalers to cooperate with purchased water systems to ensure their compliance
but, as previously mentioned, each water system is ultimately responsible for its own
compliance.
       Q:     Does this rule apply to consecutive systems that buy chlorinated water and that do not
               add a chemical disinfectant?
       A:     EPA believes that all consumers should be protected against DBPs. EPA anticipates
               clarifying requirements for those systems in the Stage 2 DBPR. Until the Stage 2 rule is
               finalized, EPA  anticipates that states will specify how consecutive systems that purchase
               disinfected water but do not add a disinfectant must monitor.
2.0   General Program Requirements


2.1    Primacy


       Q:     If the state has a blanket letter from the Attorney General that covers all regulations, does
               it have to get a new letter specifically for the Stage 1 DBPR?
       A:     Yes. States would not be able to use a letter from the Attorney General that provided
               certification of rules not in existence at the time the certification letter was written. The
               certification would also have to confirm that there are no state audit laws preventing
               enforcement of the rules.


       Q:     Do you need to adopt the PWS definition (if applicable) and obtain administrative
               penalty authority in order to receive interim primacy for the Stage I DBPR?
       A:     A state is eligible for interim primacy for new regulations provided they have primacy or
               interim primacy for all existing regulations. At a time when multiple regulations are being
               promulgated, a state qualifies for interim primacy for each rule as the rules are adopted by
               the state as long as the time period allowed for adoption (two years plus up to a two year
               extension, if applicable) has not expired.  For example, even though the CCR was
               promulgated before the Stage 1 DBPR, a state can obtain interim primacy for the Stage  1
               DBPR before the CCR, as long as the deadline to adopt the CCR has not passed.
               However, if time period allow for adoption of the CCR has passed and the state has not
               adopted the CCR, then the state would not be eligible for interim primacy for the  Stage 1
               DBPR.
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        Q:     Can states  "bundle" regulations in their primacy revision package?
        A:     Yes, states may combine two or more rules in one primacy revision package provided that
               the states' adoption of the rules falls within the statutory two year period and two year
               extension period, if applicable.


        Q:     May a state adopt the Stage 1 DBPR by reference?
        A:     Yes, if the state law allows this. However, the state will still need to address the special
               primacy requirements which give the state flexibility and discretion in meeting certain
               requirements.


        Q:     Our State's Attorney General does not have the authority to approve regulations.  Will
               this be a problem for us in terms of obtaining primacy for new rules?
        A:     EPA does not require the State's Attorney General to provide approval of regulations
               adopted for purposes of the state achieving primacy under these rules. The requirement is
               for a statement by the Attorney General, or the primacy agency's attorney if it has
               independent legal council, that the laws and regulations adopted by the state were duly
               adopted and are enforceable.


2.2     Violations, SDWIS Reporting and SNC Definitions


        Q:     If a system  receives 2 treatment technique violations in I month, is that counted as two
               TT violations toward SNC?
        A:     Yes.


        Q:     How frequently are SNC determinations made? Can a system potentially receive a SNC
               designation every month? every quarter? every year?
        A:     Significant Non-Compliance (SNC) determinations for all rules, including the  Interim
               Enhanced Surface Water Treatment Rule (IESWTR) and the Stage 1
               Disinfectants/Disinfection Byproducts Rule (DBPR), are made once per quarter,
               compounding over a rolling four quarter period. SDWIS guidance states that these
               determinations are made on the first day of the month following the end of the quarter
               which covers the 12 month compliance period which ended the previous quarter.


2.3     Qualified Operators


        Q:     There is a requirement of the SWTR that the systems be operated by qualified personnel.
               What if the system has a membrane plant that is not operated on a full time  basis? EPA
               has not mandated the number of hours in a operating cycle and systems have been
               installing membrane plants to prevent being required to have a full-time operator.
        A:     Both the Surface Water Treatment Rule and the Stage 1 Disinfectants/Disinfection
               Byproducts Rule require regulated systems to be operated by qualified personnel who meet
               the requirements specified by the state and are included in a state register of qualified
               operators. The rules do not, however, address the amount of time qualified operators are
               required to  spend on site at the plant. EPA believes that this type of determinations should
               be left to the states' discretion.
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        Q:     Who in the state must maintain the list of qualified operators? Is it acceptable if the
               Public Water Supply Supervision Program (PWSS) does not maintain the list, but another
               agency in the state does?
        A:     Yes, it is acceptable for a state agency other than the primacy agency to maintain the
               state's register of qualified operators. It is essential, however, for the PWSS Program to
               have access to that register.
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