National Primary Drinking Water Regulations: Stage 2 Disinfectants and Disinfection Byproducts Rule; National Primary and Secondary Drinking Water Regulations: Approval of Analytical Methods for Chemical Contaminants [[pp. 49597-49646]]

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: August 18, 2003 (Volume 68, Number 159)]
[Proposed Rules]
[Page 49597-49646]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr18au03-45]

[[pp. 49597-49646]]
National Primary Drinking Water Regulations: Stage 2
Disinfectants and Disinfection Byproducts Rule; National Primary and
Secondary Drinking Water Regulations: Approval of Analytical Methods
for Chemical Contaminants

[[Continued from page 49596]]

[[Page 49597]]

EPA is proposing to require all systems to develop and maintain a
DBP monitoring plan that must include the following information:
monitoring locations, monitoring dates, compliance calculation
procedures, and copies of any permits, contracts, or other agreements
with third parties to sample, analyze, report, or perform any other
monitoring requirement. Each system in a combined distribution system
(as discussed in section V.C) must develop and maintain its own
monitoring plan.
To comply with the requirement for a monitoring plan, systems may
develop a new plan or update the monitoring plan required under the
Stage 1 DBPR (see Sec. 141.132(f)). In either case, the system must
follow the monitoring plan, which will be based on the IDSE report
submitted to the State, modified by any changes required by the State.
Table V-5 summarizes proposed routine and reduced monitoring
requirements for Stage 2B of today's rule for non-consecutive systems
and for consecutive systems that also treat source water. Tables V-6
and V-7 summarize proposed routine and reduced Stage 2B monitoring
requirements for consecutive systems that purchase all of their
finished water year-round. The proposed reduced monitoring requirements
are consistent with the approach taken in the Stage 1 DBPR.

Table V-5.--Proposed Stage 2B Routine and Reduced Monitoring Requirements for Non-Consecutive Systems and for
Consecutive Systems That Also Treat Source Water To Produce Finished Water \1\
----------------------------------------------------------------------------------------------------------------
Requirements to Trigger for
System size and source water Routine monitoring qualify for Reduced monitoring returning to
type (per plant) \2\ reduced monitoring (per plant) routine monitoring
----------------------------------------------------------------------------------------------------------------
Subpart H systems serving Four dual sample One year of Two dual sample TOC £4.0
£=10,000 people. sets per quarter. completed routine sets per quarter. mg/L as an RAA,
monitoring and or TTHM LRAA
all TTHM and HAA5 £0.040 mg/L
LRAAs are no more or HAA5 LRAA
than 0.040 mg/L £0.030 mg/
and 0.030 mg/L, L.
respectively, and
TOC running
annual average
<=4.0 mg/L.
Subpart H systems serving 500 to Two dual sample One year of Two dual sample TOC £4.0
9,999 people. sets per quarter completed routine sets per year \4\. mg/L as an RAA,
\3\. monitoring and or Single Sample
all TTHM and HAA5 of TTHM
LRAAs are no more £0.060 mg/L or
than 0.040 mg/L HAA5
and 0.030 mg/L, £0.045 mg/L.\5\
respectively, and
TOC running
annual average
<=4.0 mg/L.
Subpart H systems serving <500 One dual sample Monitoring may not NA................ NA.
people. set per year \5\ be reduced.
\6\.
Ground water systems serving Two dual sample One year of Two dual sample Single Sample of
£=10,000 people \7\. sets per quarter completed routine sets per year \4\. TTHM
\3\. monitoring and £0.060 mg/L or
all TTHM and HAA5 HAA5
LRAAs are no more £0.045 mg/L.\5\
than 0.040 mg/L
and 0.030 mg/L,
respectively.
Ground water systems serving 500 Two dual sample One year of Two dual samples Single sample of
to 9,999 people \7\. sets per year \3\ completed routine every third year TTHM £
\5\. monitoring and \4\. eq>0.040 mg/L or
all TTHM and HAA5 HAA5
LRAAs are no more £0.030 mg/L.\5\
than 0.040 mg/L
and 0.030 mg/L,
respectively.
Ground water systems serving One dual sample One year of Two dual samples Single sample of
<500 people \7\. set per year \5\ completed routine every third year TTHM
\6\. monitoring and \4\. £0.040 mg/L or
all TTHM and HAA5 HAA5
LRAAs are no more £0.030 mg/L \5\
than 0.040 mg/L
and 0.030 mg/L,
respectively.
---------------------
Consecutive systems that also System must meet the routine and reduced monitoring requirements of a non-
treat source water. consecutive system with the same population and source water. Monitoring may
be reduced to the level required of that non-consecutive system.
----------------------------------------------------------------------------------------------------------------
\1\ Samples must be taken during representative operating conditions. Quarterly samples must be taken
approximately every 90 days.
\2\ Systems will use the results of their IDSEs and Stage 1 DBPR compliance monitoring to recommend Stage 2B
monitoring locations representative of high TTHM and HAA5 concentrations to the State in their IDSE reports.
Systems must monitor at the recommended locations unless the State requires other locations.
\3\ If site and quarter of highest individual TTHM and HAA5 measurement are the same, monitoring is only
required at one location if State approves.
\4\ If site and quarter of highest individual TTHM and HAA5 measurement are the same, monitoring is only
required at one location.
\5\ If any single sample of TTHM £0.080 mg/L or HAA5 £0.060 mg/L, system must go to
increased monitoring of quarterly dual samples at each routine monitoring location and can return to routine
monitoring when TTHM <=0.060 mg/L and HAA5 <=0.045 mg/L as LRAAs.
\6\ If the site or month of highest TTHM is not the same as the site or month of highest HAA5, the system must
monitor for TTHM at the location of the highest TTHM LRAA during the month of highest TTHM single measurement
and for HAA5 at the location of the highest HAA5 LRAA during the month of highest HAA5 single measurement.
\7\ Ground water systems are those not under the direct influence of surface water. For the purpose of
determining the required number of samples, multiple wells drawing water from a single aquifer may, with State
approval, be considered one treatment plant.

i. Subpart H systems serving 10,000 or more people.
Routine monitoring: Systems must take four dual sample sets (i.e.,
a TTHM and an HAA5 sample must be taken at each sampling site) per
treatment plant per quarter. Systems must monitor at locations
recommended in the IDSE report, unless the State has required other
locations. Most systems must take samples at each plant in the system
as follows: One dual sample set at the existing Stage 1 DBPR average
residence time monitoring location with the highest TTHM or HAA5 LRAA,
one dual sample set at a point representative of the highest HAA5
levels, and two dual sample sets at points representative of the
highest TTHM levels.
Systems must schedule monitoring so that one quarter's monitoring
is conducted during the peak historical month for high TTHM
concentration and the other quarterly monitoring is

[[Page 49598]]

conducted approximately every 90 days on a predetermined schedule
included in the system's monitoring plan.
Reduced monitoring: Only systems with source water TOC <=4.0 mg/L
as an RAA that have completed at least one year of routine monitoring
may qualify for reduced monitoring (see Table V-5). Systems that have a
TTHM LRAA <=0.040 mg/L and an HAA5 LRAA <=0.030 mg/L at all sites, in
addition to a source water TOC RAA <= 4.0 mg/L, may reduce the
monitoring frequency for TTHM and HAA5 to two dual sample sets (one
each at sites representative of the highest HAA5 and TTHM LRAAs) per
treatment plant per quarter. Systems on a reduced monitoring schedule
may remain on that reduced schedule as long as the LRAA of all samples
taken in the year is no more than 0.040 mg/L for TTHM and 0.030 mg/L
for HAA5 or if source water TOC exceeds 4.0 mg/L as an RAA. Systems
must revert to routine monitoring in the quarter immediately following
any quarter in which the LRAA for any monitoring location exceeds 0.040
mg/L for TTHM or 0.030 mg/L for HAA5. Additionally, the State may
return a system to routine monitoring at the State's discretion.
Compliance determination: A PWS is in compliance with Stage 2B when
the TTHM and HAA5 LRAAs for each sample location, computed quarterly,
are less than or equal to the Stage 2B MCLs of 0.080 mg/L and 0.060 mg/
L, respectively. Otherwise, the system is out of compliance.
ii. Subpart H systems serving 500 to 9,999 people. Routine
monitoring: Systems must monitor quarterly for each treatment plant by
taking two dual sample sets, one each at sites representative of high
HAA5 levels and high TTHM levels (as recommended in the IDSE report).
However, if the State determines that the sites representative of the
high TTHM and HAA5 levels are at the same location, the State may
determine that the system is only required to monitor at one site per
treatment plant.
Systems must conduct quarterly monitoring during the peak
historical month for TTHM with quarterly samples taken approximately
every 90 days on a predetermined schedule specified in the system's
monitoring plan. All samples must be taken as dual sample sets (i.e., a
TTHM and an HAA5 sample must be taken at each site).
Reduced monitoring: To qualify for reduced monitoring, systems must
meet certain prerequisites (see Table V-5). Systems eligible for
reduced monitoring may reduce the monitoring frequency from quarterly
to annually. Samples must be taken during the month(s) of peak
historical TTHM and HAA5 levels at the same locations specified under
routine monitoring. Systems that have their highest TTHM and HAA5
levels in the same month must take dual sample sets at both the high
TTHM and high HAA5 sites. If the high months for TTHM and HAA5 are not
the same, the system must take dual sample sets in both the high TTHM
and high HAA5 months. Systems on a reduced monitoring schedule may
remain on that reduced schedule as long as the annual sample taken at
each location is no more than 0.060 mg/L for TTHM and 0.045 mg/L for
HAA5 or if source water TOC exceeds 4.0 mg/L as an RAA. Systems that do
not meet these levels must revert to routine monitoring in the quarter
immediately following the quarter in which the system exceeded 0.060
mg/L for TTHM or 0.045 mg/L for HAA5. Additionally, the State may
return a system to routine monitoring at the State's discretion.
Compliance determination: A PWS is in compliance with Stage 2B when
the LRAAs of each sample location, computed quarterly, are less than or
equal to the MCLs. Otherwise, the system is out of compliance. If the
annual sample taken under reduced monitoring exceeds the MCL, the
system must resume quarterly monitoring but is not immediately in
violation of the MCL. The system is out of compliance if the LRAA of
the quarterly sample for the past four quarter exceeds the MCL.
iii. Subpart H systems serving fewer than 500 people. Routine
monitoring: Systems are required to sample annually for each treatment
plant at the location with high TTHM and HAA5 values during the month
of peak historical TTHM levels. The system must take one dual sample
set at the site representative of the high HAA5 and TTHM levels (at the
Stage 1 DBPR monitoring site or as recommended in the IDSE report),
unless the State determines that the highest TTHM site and the highest
HAA5 site are not at the same location or are not during the same
quarter. If the State determines that the highest TTHM and highest HAA5
do not occur in the same location, the system is required to take two
samples, an HAA5 sample at the site representative of the high HAA5
levels and a TTHM sample at the site representative the high TTHM
levels. If the State determines that the highest TTHM and highest HAA5
do not occur in the same quarter, the systems is required to take one
sample in the high TTHM quarter and one sample in the high HAA5
quarter. If the annual sample exceeds the MCL for either TTHM or HAA5,
the system must monitor quarterly at the previously determined
monitoring locations.
Reduced monitoring: These systems may not reduce monitoring to less
frequently than annually. Systems on increased (quarterly) monitoring
may return to routine monitoring if the LRAAs of quarterly samples are
no more than 0.060 mg/L for TTHM and 0.045 mg/L for HAA5.
Compliance determination: A PWS is in compliance when the annual
sample (or LRAA of quarterly samples, if increased or additional
monitoring is conducted) is less than or equal to the MCL. If the
annual sample exceeds the MCL, the system must conduct increased
(quarterly) monitoring but is not immediately in violation of the MCL.
The system is out of compliance if the LRAA of the quarterly samples
for the past four quarters exceeds the MCL.
iv. Ground water systems serving 10,000 or more people. Routine
monitoring: Systems are required to monitor quarterly for each
treatment plant in the system by taking two dual sample sets, one each
at sites representative of high HAA5 levels and high TTHM levels (as
recommended in the IDSE report). However, if the State determines that
the sites representative of the high TTHM and HAA5 levels are the same,
the State may determine that the system only has to monitor at one site
per treatment plant. One quarterly sample must be taken during the peak
historical month for TTHM, with subsequent quarterly samples taken
approximately every 90 days.
Reduced monitoring: To qualify for reduced monitoring, systems must
meet certain requirements (see Table V-5). Systems eligible for reduced
monitoring may reduce the monitoring frequency from quarterly to
annually. Samples must be taken during the month(s) of peak historical
TTHM and HAA5 levels at the same locations specified under routine
monitoring. Systems that have their highest TTHM and HAA5 levels in the
same quarter must take dual sample sets at both the high TTHM and high
HAA5 sites. If the quarter for high TTHM and high HAA5 are not the
same, the system must take dual sample sets in both the high TTHM and
high HAA5 quarters. Systems on a reduced monitoring schedule may remain
on that reduced schedule as long as the annual sample taken at each
location is no more than 0.060 mg/L for TTHM and 0.045 mg/L for HAA5.
Systems that do not meet these levels must revert to routine monitoring
in the quarter immediately following the quarter in which the system
exceeded 0.060 mg/L for TTHM or 0.045 mg/L for HAA5. Additionally, the
State may return a

[[Page 49599]]

system to routine monitoring at the State's discretion.
Compliance determination: A PWS is in compliance with Stage 2B when
the locational running annual average of each sample location, computed
quarterly, is less than or equal to the MCL. Otherwise, the system is
out of compliance. If the annual sample exceeds the MCL, the system
must conduct increased (quarterly) monitoring but is not immediately in
violation of the MCL. The system is out of compliance if the LRAA of
the quarterly sample for the past four quarter exceeds the MCL.
v. Ground water systems serving fewer than 10,000 people. Routine
monitoring: Systems serving 500 to 9,999 people are required to take
two dual sample sets annually, one each at sites representative of high
HAA5 levels and high TTHM levels (as recommended in the IDSE report).
However, if the State determines that the sites representative of the
high TTHM and HAA5 levels are the same, the State may allow the system
to monitor at only one site per treatment plant. If the State makes a
determination that high TTHM and high HAA5 occur in different quarters,
the system must monitor accordingly. If the annual sample exceeds the
MCL for either TTHM or HAA5, the system must monitor quarterly at the
previously determined monitoring locations.
Systems serving fewer than 500 people are required to take one dual
sample set at the site representative of both high HAA5 and TTHM
levels, unless the State determines that the high TTHM site and the
high HAA5 site are not at the same location. If the State makes this
determination, the system is required to take samples at two locations,
an HAA5 sample at the site representative of the high HAA5 levels and a
TTHM sample at the site representative of the high TTHM levels. If the
State makes a determination that high TTHM and high HAA5 occur in
different quarters, the system must monitor accordingly. If the annual
sample exceeds the MCL for either TTHM or HAA5, the system must monitor
quarterly at the previously determined monitoring locations.
Reduced monitoring: To qualify for reduced monitoring, systems must
meet certain prerequisites (see Table V-5). Systems eligible for
reduced monitoring may reduce the monitoring frequency for TTHM and
HAA5 to every third year. Systems are required to take two water
samples, at sites representative of high HAA5 and TTHM levels (as
discussed under routine monitoring) during the month of peak TTHM
levels. Systems on a reduced monitoring schedule may remain on that
reduced schedule as long as the sample taken every third year is no
more than 0.040 mg/L for TTHM and 0.030 mg/L for HAA5. Systems that do
not meet these levels must resume routine annual monitoring until their
annual average is no more than 0.040 mg/L for TTHM and 0.030 mg/L for
HAA5.
Compliance determination: A PWS is in compliance when the annual
sample (or LRAA of quarterly samples, if increased or additional
monitoring is conducted) is less than or equal to the MCL. If the
annual sample exceeds the MCL, the system must conduct increased
(quarterly) monitoring but is not immediately in violation of the MCL.
The system is out of compliance if the LRAA of the quarterly samples
for the past four quarters exceeds the MCL.
vi. Consecutive systems. Routine monitoring: Monitoring
requirements are determined by whether the consecutive system purchases
all of its finished water year-round or also treats source water, along
with the population served and source water type of the wholesale
system (unless the consecutive system also has a surface water or
ground water under the direct influence of surface water (GWUDI) source
and the wholesale system is only ground water, in which case the
consecutive system is classified as a subpart H system). Section V.C.
of today's document provides a more detailed discussion of consecutive
system issues.
As noted earlier, for consecutive systems that purchase all their
finished water year-round, EPA is proposing population-based
monitoring. The proposed number of monitoring locations is based on the
source water type of the wholesale system and consecutive system
population. Proposed Stage 2B compliance monitoring requirements for
consecutive systems that purchase all their finished water are
contained in Table V-6. Consecutive systems that also treat source
water to produce finished water must monitor at the same locations and
same frequency as a non-consecutive system with the wholesale system's
source water type and the consecutive system's population.

Table V-6.--Proposed Population-Based Routine Monitoring Routine Frequencies and Locations Under Stage 2B for Consecutive Systems That Purchase All
Their Finished Water Year-Round
--------------------------------------------------------------------------------------------------------------------------------------------------------
Distribution system sample location \2\
-----------------------------------------------
Existing
Source water type Population size category Monitoring frequency \1\ Highest Highest stage 1
Total TTHM HAA5 compliance
locations locations locations
\3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H.......................... 0-499................................ per year.................... 2 \4\ 1 1 ...........
500-4,999............................ per quarter................. 2 \4\ 1 1 ...........
5,000-9,999.......................... per quarter................. 2 1 1 ...........
10,000-24,999........................ per quarter................. 4 2 1 1
25,000-49,999........................ per quarter................. 6 3 2 1
50,000-99,999........................ per quarter................. 8 4 2 2
100,000-499,999...................... per quarter................. 12 6 3 3
500,000-1,499,000.................... per quarter................. 16 8 4 4
1,500,000-4,999,999.................. per quarter................. 20 10 5 5
£=5,000,000................ per quarter................. 24 12 6 6
0-499................................ per year.................... 2 \4\ 1 1 ...........
500-9,999............................ per year.................... 2 1 1 ...........
Ground Water....................... 10,000-99,999........................ per quarter................. 4 2 1 1
100,000-499,999...................... per quarter................. 6 3 2 1
£=500,000.................. per quarter................. 8 4 2 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ All systems must take at least one dual sample set during month of highest DBP concentrations. Systems on quarterly monitoring must take dual sample
sets approximately every 90 days.

[[Page 49600]]

\2\ Locations based on system recommendations for Stage 2B monitoring locations in IDSE report to the State, unless State requires different or
additional locations. Locations should be distributed through distribution system to the extent possible.
\3\ Alternate between highest HAA5 LRAA and highest TTHM LRAA locations among the existing Stage 1 compliance locations. If the number of existing Stage
1 compliance locations is fewer than the specified number for Stage 2B, alternate between highest HAA5 LRAA locations and highest TTHM LRAA locations
from the IDSE.
\4\ System is required to take individual TTHM and HAA5 samples at the locations with the highest TTHM and HAA5 concentrations, respectively. Only one
location with a dual sample set per monitoring period is needed if highest TTHM and HAA5 concentrations occur at the same location.

Reduced monitoring: Consecutive systems can qualify for reduced
monitoring if the LRAA at each location is <=0.040 mg/L for TTHM and
<=0.030 mg/L for HAA5 based on at least one year of monitoring at Stage
2B locations. Consecutive systems that purchase all of their finished
water year-round may reduce their monitoring as specified in Table V-7.
Consecutive systems that also treat source water to produce finished
must conduct reduced monitoring at the same locations and same
frequency as a non-consecutive system with the wholesale system's
source water type and the consecutive system's population.

Table V-7.--Reduced Monitoring Frequency for Consecutive Systems That
Buy All Their Water
------------------------------------------------------------------------
Population served Reduced monitoring frequency and location
------------------------------------------------------------------------
Subpart H systems
------------------------------------------------------------------------
<500......................... Monitoring may not be reduced.
500 to 4,999................. 1 TTHM and 1 HAA5 sample per year at
different locations or during different
quarters if the highest TTHM and HAA5
occurred at different locations or
different quarters or 1 dual sample per
year if the highest TTHM and HAA5
occurred at the same location and
quarter.
5,000 to 9,999............... 2 dual sample sets per year; one at the
location with the highest TTHM single
measurement during the quarter that the
highest single TTHM measurement
occurred, one at the location with the
highest HAA5 single measurement during
the quarter that the highest single HAA5
measurement occurred.
10,000 to 24,999............. 2 dual sample sets per quarter at the
locations with the highest TTHM and
highest HAA5 LRAAs.
25,000 to 49,999............. 2 dual sample sets per quarter at the
locations with the highest TTHM and
highest HAA5 LRAAs.
50,000 to 99,000............. 4 dual sample sets per quarter at the
locations with the two highest TTHM and
two highest HAA5 LRAAs.
100,000 to 499,999........... 4 dual sample sets per quarter at the
locations with the two highest TTHM and
two highest HAA5 LRAAs.
500,000 to 1,499,999......... 6 dual sample sets per quarter at the
locations with the three highest TTHM
and three highest HAA5 LRAAs.
1,500,000 to 4,999,999....... 6 dual sample sets per quarter at the
locations with the three highest TTHM
and three highest HAA5 LRAAs.
£=5,000,000........ 8 dual sample sets per quarter at the
locations with the four highest TTHM and
four highest HAA5 LRAAs.
------------------------------
Ground water systems
------------------------------------------------------------------------
<500......................... 1 TTHM and 1 HAA5 sample every third year
at different locations or during
different quarters if the highest TTHM
and HAA5 occurred at different locations
or different quarters or 1 dual sample
every third year if the highest TTHM and
HAA5 occurred at the same location and
quarter.
500 to 9,999................. 1 TTHM and 1 HAA5 sample every year at
different locations or during different
quarters if the highest TTHM and HAA5
occurred at different locations or
different quarters or 1 dual sample
every year if the highest TTHM and HAA5
occurred at the same location and
quarter.
10,000 to 99,000............. 2 dual sample sets per year; one at the
location with the highest TTHM single
measurement during the quarter that the
highest single TTHM measurement occurred
and one at the location with the highest
HAA5 single measurement during the
quarter that the highest single HAA5
measurement occurred.
100,000 to 1,499,999......... 2 dual sample sets per quarter; at the
locations with the highest TTHM and
highest HAA5 LRAAs.
£=1,500,000........ 4 dual sample sets per quarter; at the
locations with the two highest TTHM and
two highest HAA5 LRAAs.
------------------------------------------------------------------------

Systems may remain on reduced monitoring as long as the TTHM LRAA
<=0.040 mg/L and the HAA5 LRAA <=0.030 mg/L at each monitoring location
for systems with quarterly reduced monitoring. If the LRAA at any
location exceeds either 0.040 mg/L for TTHM or 0.030 mg/L for HAA5 or
if the source water annual average TOC level, before any treatment,
exceeds 4.0 mg/L at any of the system's treatment plants treating
surface water or ground water under the direct influence of surface
water, the system must resume routine monitoring. For systems with
annual or less frequent reduced monitoring, systems may remain on
reduced monitoring as long as each TTHM sample <=0.060 mg/L and each
HAA5 sample <=0.045 mg/L. If the annual sample at any location exceeds
either 0.060 mg/L for TTHM or 0.045 mg/L for HAA5, or if the source
water annual average TOC level, before any treatment, exceeds 4.0 mg/L
at any treatment plant treating surface water or ground water under the
direct influence of surface water, the system must resume routine
monitoring.
Compliance determination: A PWS is in compliance when the annual
sample or LRAA of quarterly samples is less than or equal to the MCLs.
If an annual sample exceeds the MCL, the system must conduct increased
(quarterly) monitoring but is not immediately in violation of the MCL.
The system is out of compliance if the LRAA of the quarterly samples
for the past four quarters exceeds the MCL.
2. How Was This Proposal Developed?
The proposed monitoring requirements for the IDSE and Stage 2B
primarily follow a plant-based approach that was adopted from the 1979
TTHM Rule and the Stage 1 DBPR. This approach includes differences in
monitoring frequency between surface water and ground water sources,
and between large and small systems. However, the proposed monitoring
requirements differ from Stage 1 DBPR requirements in certain areas,
including (a) sampling intervals for quarterly monitoring, (b) reduced
monitoring frequency, (c) different sampling locations by disinfectant
type (for the IDSE), and (d) population-based monitoring requirements
for certain consecutive systems. This subsection

[[Page 49601]]

presents the basis for these requirements.
a. Sampling intervals for quarterly monitoring. Today's proposal
requires systems conducting routine quarterly monitoring to sample
approximately every 90 days. This provision modifies the approach used
in the 1979 TTHM rule and the Stage 1 DBPR, which requires certain
systems to conduct monitoring based on calendar quarters.
When systems are required to monitor based on calendar quarters,
systems can choose to cluster samples during times of the year when DBP
levels are lower (DBPs tend to form more slowly in colder water
temperatures). For example, a system could sample in December (at the
end of the fourth quarter) and again in January (at the beginning of
the first quarter) when the water is the coldest and sample in April
(at the beginning of the second quarter) and September (at the end of
the third quarter) at either end of the hot summer months.
To address the concern with systems not sampling during months with
the highest DBP levels, EPA is proposing to require systems to monitor
during the month of highest historical DBP concentrations and require
that systems monitor approximately every 90 days. EPA believes that
this new monitoring strategy will improve public health protection
because systems will be required to monitor when high DBP levels are
expected, and the LRAA will better reflect actual exposure during the
year.
b. Reduced monitoring frequency. Today's proposal contains
provisions allowing reduced routine monitoring when certain criteria
are fulfilled (shown in Table V-5 and V-7). EPA believes that more
stringent standards are necessary to ensure public health protection
when systems reduce the frequency of their DBP monitoring. Under the
reduced monitoring provisions, systems must collect samples during the
months of highest DBP occurrence. For systems sampling annually under
the reduced monitoring provisions, EPA believes that public health
protection would likely be ensured throughout the year if the high
values are known to be below 0.060 mg/L for TTHM and 0.045 mg/L for
HAA5. Systems monitoring every three years must maintain single samples
under 0.040 mg/L for TTHM and 0.030 mg/L for HAA5 to ensure adequate
public health protection over the course of the three years.
c. Different IDSE sampling locations by disinfectant type. Today's
proposal contains different requirements for IDSE monitoring locations
based on the disinfectant residual used in the distribution system.
Systems that use chloramines are required to select more near-entry
point monitoring sites for the IDSE than chlorinated systems of similar
size and source water type. This is due to differences in DBP formation
under chloraminated and chlorinated conditions. Chloramine residuals
are more stable than chlorine residuals and do not react as readily
with organic compounds in the water. Based on evaluation of Information
Collection Rule data, DBP concentrations in chloraminated systems vary
less throughout the distribution system than in chlorinated systems.
HAA5, in particular, can peak at or near the entry point to the
distribution system in a chloraminated system (USEPA 2003o).
d. Population-based monitoring requirements for certain consecutive
systems. While the Advisory Committee recommended basic principles for
how consecutive systems should be regulated, it did not recommend how
EPA should explicitly address some of the unique situations that
pertain to consecutive systems. In this regard, consecutive systems
that purchase all of their finished water year-round are different than
other systems in that they do not have a treatment plant. Rather, these
systems often receive water from multiple wholesale systems or through
multiple consecutive system entry points on a seasonal or intermittent
basis. Because a plant-based monitoring approach (which counts treated
water distribution system entry points from different entities as
plants) would be very difficult to implement for consecutive systems
that purchase all of their finished water year-round, EPA is proposing
a population-based approach for such systems.
Under a population-based approach, the frequency of monitoring is
based on the population served and remains the same regardless of how
many entities are providing water to the consecutive system at
different times of the year. The population categories and associated
monitoring frequencies in Tables V-4 and V-6 for IDSE and Stage 2B
routine monitoring reflect EPA's consideration that distribution system
complexity generally increases as the population served grows.
Increasing distribution system complexity warrants more monitoring to
represent DBP occurrence.
EPA developed the proposed population-based monitoring requirements
in accordance with certain guidelines. These are stated as follows:

--The sampling frequency for surface water systems should be greater
than for ground water systems. The basis for this is that, in general,
systems using surface water or mixed source water supplies are likely
to experience higher and more variable DBP occurrence over time than
systems using ground water exclusively.
--Smaller systems should be allowed to monitor less frequently per
location than larger systems because their distribution systems are
generally less complex and monitoring costs on a per capita basis are
much higher.
--For systems using surface water, the ratio of IDSE sample locations
to the number of routine sample locations required for Stage 2B should
be approximately 2:1 (consistent with Advisory Committee
recommendations for plant-based monitoring). IDSE sampling is intended
to identify distribution system locations with high DBP levels and
should, therefore, be more thorough than routine monitoring.
--Because ground water systems have much less variable DBP levels
within the distribution system than surface water systems (see section
IV), a smaller number of additional IDSE monitoring locations is
warranted.
--Distribution system sampling locations should be approximately
consistent with the proposed plant-based approach as recommended by the
Advisory Committee. This will capture the locations with the high TTHM
and HAA5 LRAAs identified in the IDSE, but also include Stage 1
compliance locations with high TTHM and HAA5 for historical tracking.

Consistent with the first two guidelines, the proposed population-
based monitoring requirements maintain the same monitoring frequency
per sample location as proposed under the plant-based approach. The
following subsection provides further discussion of the population-
based approach as it might apply to all systems.
3. Request For Comment
EPA is requesting comments on the proposed monitoring requirements.
This subsection begins with a list of specific questions related to the
proposed requirements for IDSE and Stage 2B monitoring. This is
followed by a discussion of issues associated with plant-based
monitoring requirements and a request for comment on potential
approaches to address these issues, including the extension of
population-based monitoring requirements to all systems under the Stage
2 DBPR.
a. Proposed IDSE and Stage 2B monitoring requirements. EPA is

[[Page 49602]]

requesting comment on a number of specific aspects of the proposed
monitoring requirements.

--Should EPA require all systems that are on reduced monitoring to
revert to routine monitoring during the IDSE monitoring period to allow
for more data to be evaluated in the IDSE report to better select Stage
2B monitoring locations? Or should EPA require a system to be on
routine monitoring during the IDSE monitoring period in order to be
eligible for an IDSE waiver? What limitations, if any, should EPA put
on system eligibility for an IDSE waiver?
--Should EPA require different IDSE monitoring locations for subpart H
systems based on the residual disinfectant (chlorine or chloramines) in
light of the possible difficulties for implementation and data
management? Should EPA specify monitoring locations in the rule
language for samples intended to represent exposure for people in high-
rise buildings? Should monitoring location selection be addressed in
guidance? Where should these locations be so that they are truly
representative of the levels of DBPs in water actually being consumed
in these kinds of structures?
--Is a population-based monitoring approach (instead of a plant-based
monitoring approach) for consecutive systems that purchase all of their
finished water year-round appropriate and, if so, is the population-
based approach proposed today adequate?

EPA solicits comment on the significance of monitoring and
implementation issues such as common aquifer determinations,
consecutive system entry point determinations, seasonal plants, and
monitoring inequities, and whether the proposed monitoring requirements
should be modified. EPA also solicits comment on modifying the proposed
monitoring requirements to address these issues, in part, with
provisions such as the following:

--Should EPA set a limit on the maximum number of IDSE and routine
monitoring samples that could be required? Should this limit be
different for systems using ground water or surface water or mixed
systems? For different system size categories? What rationale should be
used to specify maximum sample numbers?
--Should a provision be included that would allow States to reduce the
sampling frequency, beyond those currently proposed (i.e., common
aquifer determinations and low DBP levels)? If so, should specific
criteria for systems to qualify for State approval of reduced
monitoring be specified in the rule?
--What, if any, criteria should be set by which systems with very large
distribution systems but few plants would be required to conduct
additional IDSE or routine monitoring, beyond that currently proposed?
--For subpart H mixed systems, should States be given discretion to
reduce routine compliance monitoring samples intended to represent
ground water sources, since such sources typically have lower precursor
levels and produce lower DBP concentrations?
--Should EPA allow or require systems to reallocate plant-based IDSE
monitoring locations from small plants to large plants? From plants
with better water quality (based on expected lower DBP formation) to
poorer water quality? What criteria should be used?

b. Plant-based vs. population-based monitoring requirements. The
proposed monitoring requirements incorporate a plant-based approach for
all systems other than consecutive systems that purchase all of their
finished water year-round. The plant-based approach was adopted from
the 1979 TTHM Rule and the Stage 1 DBPR and derives from the assumption
that as systems increase in size, they will tend to have more plants
(with different sources and treatment) and increased complexity. This
warrants increased monitoring to represent DBP occurrence in the
distribution system.
EPA has identified a number of issues related to the use of a
plant-based monitoring approach under the Stage 2 DBPR. The following
discussion presents these issues and solicits comment on approaches to
address them, including the use of population-based monitoring
requirements.
i. Issues with plant-based monitoring requirements. One issue with
a plant-based monitoring approach is that it can result in
disproportionate monitoring requirements for systems serving the same
number of people. This occurs because the required number of sampling
sites increases with the number of plants that feed disinfected water
into a distribution system. Consequently, some systems, depending upon
their size, the number of treatment plants, and the nature of their
distribution system, will be required to collect relatively large or
small numbers of TTHM and HAA5 samples relative to their population
served.
Table V-8 reflects EPA estimates of the number of plants per system
by system size category for systems using ground water and subpart H
systems. Subpart H systems include systems that use ground water as a
source because under the proposal, ground water plants in subpart H
systems are treated as surface water plants for purposes of determining
monitoring requirements. While the proposed plant-based requirements
distinguish sampling requirements by three systems sizes (<500 people,
500-9999 people, and 10,000 or more people), Table V-8 includes
additional size categories to reflect the potential inequities in
sampling requirements among different-sized systems.

Table V-8.--Number of Treatment Plants per System (Based on Data From 1995 CWSS (1))
--------------------------------------------------------------------------------------------------------------------------------------------------------
No. of treatment plants per system
No. of ---------------------------------------------------------------------
Source water type Population served systems in 10th 90th 95th
database percentile Median Mean percentile percentile Maximum
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H........................... 0-499.......................... 124 1 1 1.4 2 3 5
500-4,999...................... 146 1 1 1.3 2 3 6
5,000-9,999.................... 64 1 1 1.7 3 4 6
10,000-24,999.................. 59 1 1 2.0 3 4 18
25,000-49,999.................. 46 1 1 2.2 4 6 9
50,000-99,999.................. 76 1 2 3.4 6 12 34
100,000-499,999................ 51 1 2 3.0 5 10 21
£=500,000............ 23 2 4 5.8 10 13 56
Ground Water........................ 0-499.......................... 181 1 1 1.4 3 4 11
500-9,999...................... 332 1 1 1.8 3 4 13

[[Page 49603]]

10,000-99,999.................. 128 1 4 4.2 9 11 18
£=100,000............ 21 1 3 9.9 31 32 33
--------------------------------------------------------------------------------------------------------------------------------------------------------
(1) Results from analysis of 1995 CWSS data (Question Q18). The analysis uses a statistical bootstrapping approach to generate the number of plants per
system. Details of this analysis are described in the 2002 revisions to the Model Systems Report [to be published]. The maximums reflect the maximum
number of plants per system among the respondents to the 1995 CWSS. Since the 1995 CWSS database only reflects a fraction of all the systems in the
respective size categories, some systems are likely to have a higher number of plants per system than the maximums listed in this table.

Noteworthy in Table V-8 are the wide ranges of number of plants per
system in the various size categories for both ground water and surface
water systems and, consequently, the wide range of potential monitoring
implications. Since the number of treatment plants directly influences
the number of samples required, systems serving the same number of
people may have more than a 10-fold difference in required sampling,
depending on the numbers of plants in their systems. For example, Table
V-8 indicates that for ground water systems serving at least 10,000
people, at least 10% of the systems had only one treatment plant, while
10% (90th percentile) had 10 or more treatment plants.
While Table V-8 does not take into account factors that may reduce
monitoring requirements, such as common aquifer determinations, EPA
believes these data indicate that DBP sampling requirements based on
the number of water treatment plants per system may be excessive for
many systems. This is particularly the case for those systems with many
ground water plants, since their DBP levels are often low and
relatively stable.
Conversely, for other systems, such as large surface water systems
with one plant, plant-based monitoring requirements may not require
enough samples to fairly represent DBP occurrence in the distribution
system. For example, under the plant-based approach, a system with only
one plant serving 100,000--499,000 people would have the same sampling
requirements as a system with one plant serving 11,000 people. The
larger of these two systems is likely to have much more pipe length and
other complex factors influencing DBP formation (such as number of
storage tanks or booster chlorination points in the distribution
system). Also, systems with multiple plants must take the same number
of samples per plant, even if one plant provides a much higher
percentage of the water than another.
Another issue with plant-based monitoring requirements is when
plants or consecutive system entry points are operated seasonally or
intermittently. A monitoring location that represents a plant or entry
point during a monitoring period when it is in operation will not be
representative when that plant or entry point it is not in operation.
A third issue is requirements for consecutive systems. For
consecutive systems that also treat source water to produce finished
water, each consecutive system entry point is considered a treatment
plant for the purpose of determining monitoring requirements, except
when the State allows multiple entry points to be treated as a single
plant (see section V.C. for further discussion). Each entry point is
treated as a separate plant to recognize different source waters and
treatment (resulting in different DBP levels) from the wholesale
system(s) and the treatment plants(s) operated by the consecutive
system. However, under this plant-based approach, State determinations
of monitoring requirements for consecutive systems will be complicated,
especially in large combined distribution systems with many connections
between systems.
ii. Approaches to addressing issues with plant-based monitoring.
EPA is requesting comment on two approaches to address the issues with
plant-based monitoring requirements described in this subsection. One
approach is to keep the proposed plant-based monitoring approach and
add new provisions to address specific concerns. Another approach is to
base monitoring requirements on population served in lieu of the number
of water treatment plants per system. The following paragraphs describe
each approach.
EPA could maintain a plant-based monitoring approach and try to
address the related issues described in this subsection through
modifying the proposed monitoring requirements with provisions like the
following:

--Set a limit on the maximum number of IDSE and routine monitoring
samples that could be required. EPA believes that this limit should be
different for systems using ground water or surface water or mixed
systems and for different system size categories. However, the Agency
has not developed a rationale to specify maximum sample numbers for
specific system categories.
--Include a provision that would allow States to reduce the required
number of samples for reasons other than those currently proposed
(i.e., common aquifer determinations and low DBP levels). EPA would
have to develop specific criteria in the rule for systems to qualify
for State approval of reduced monitoring. For example, in subpart H
mixed systems, States could be given discretion to reduce routine
compliance monitoring for ground water sources, since such sources
typically have lower DBP concentrations.
--Develop criteria by which systems with very large distribution
systems but with few plants would be required to conduct additional
IDSE or routine monitoring in order to better characterize DBP exposure
throughout the distribution system.

These provisions would allow for some issues to be addressed, but
would make implementation complex and could add a significant burden to
States.
An alternative approach to addressing the issues with plant-based
monitoring requirements is to apply population-based monitoring
requirements to all systems. Under a population-based monitoring
approach, the total system population served and the source water type
would determine the number of IDSE and routine monitoring samples
taken. Monitoring requirements would not be based on the number of
plants per system or consecutive system entry points. States would not
be required to make common aquifer determinations or address whether
plants are combined into a single pipe prior to entering the
distribution system.
Proposed population-based monitoring requirements for

[[Page 49604]]

consecutive systems that purchase all their finished water year-round
are shown in Tables V-4, V-6, and V-7. Also, the proposed rule language
in subparts U and V contains requirements for population-based
monitoring similar to what might be required for all systems. EPA
believes that through using a broader array of system size categories
than under the plant-based approach, population-based monitoring could
result in an equitable proportioning of DBP sampling requirements.
Tables V-9 and V-10 compare the proposed numbers of sampling locations
per system under a population-based approach with a plant-based
approach, using the median and mean number of plants per system given
in Table V-8 for each of the size categories. For surface water
systems, the median provides a better indicator of the typical number
of required sampling locations under the plant-based approach because
it is much less sensitive to systems with a very large number of
plants.

Table V-9.--Comparison of Monitoring Locations per System Under IDSE for Plant-Based and Population-Based Approaches
--------------------------------------------------------------------------------------------------------------------------------------------------------
Plant-based Population-based
---------------------------------------------------------------------
Number of monitoring locations per
Number of Number of system Number of
Source water type Population size category sampling monitoring ------------------------------------ monitoring
periods locations per Based on median Based on mean locations per
plant \1\ number of plants number of plants system \3\
per system \2\ per system \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H......................... 0-499.............................. 2 2 2 3 2
500-4,999.......................... 4 2 2 3 2
5,000-9,999........................ 4 2 2 3 4
10,000-24,999...................... 6 8 8 16 8
25,000-49,999...................... 6 8 8 18 12
50,000-99,999...................... 6 8 16 27 16
100,000-499,999.................... 6 8 16 24 24
500,000-1,499,000.................. ......... .............. ................ ................ 32
1,500,000-4,999,999................ 6 8 32 46 40
£=5,000,000.............. ......... .............. ................ ................ 48
Ground Water...................... 0-499.............................. 2 2 2 2 2
500-9,999.......................... 2 2 2 4 2
10,000-99,999...................... 4 2 8 9 6
100,000-499,999.................... 4 2 6 20 8
£=500,000................ ......... .............. ................ ................ 12
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ From Table V-5.
\2\ Calculated from the number of locations per plant multiplied by number of plants per system (Table V-8).
\3\ From Table V-4.

Table V-10.--Comparison of Routine Monitoring Locations per System Under Stage 2B for Plant-Based and Population-Based Approaches
--------------------------------------------------------------------------------------------------------------------------------------------------------
Plant-based Population-based
----------------------------------------------------------------------
Number of monitoring locations per
Frequency Number of system Number of
Source water type Population size category of monitoring ------------------------------------ monitoring
monitoring locations per Based on median Based on mean locations per
plant \1\ number of plants number of plants system \3\
per system \2\ per system \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H........................ 0-499............................. 1 1 1 1 2
500-4,999......................... 4 2 2 3 2
5,000-9,999....................... 4 2 2 3 2
10,000-24,999..................... 4 4 4 8 4
25,000-49,999..................... 4 4 4 9 6
50,000-99,999..................... 4 4 8 14 8
100,000-499,999................... 4 4 8 12 12
500,000-1,499,000................. .......... ............... ................ ................ 16
1,500,000-4,999,999............... 4 4 16 23 20
£=5,000,000............. .......... ............... ................ ................ 24
Ground Water..................... 0-499............................. 1 1 1 1 2
500-9,999......................... 1 2 2 4 2
10,000-99,999..................... 4 2 8 9 4
100,000-499,999................... 4 2 6 20 6
£=500,000............... .......... ............... ................ ................ 8
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ From Table V-5.
\2\ Calculated from the number of locations per plant multiplied by number of plants per system (Table V-8).
\3\ From Table V-6.

[[Page 49605]]

Under the population-based approach, the number of required
sampling locations for systems of different size and source water type
approximates the number of sampling locations that would be required
for the majority of systems under the plant-based approach. However,
systems in the tail ends of the distribution of number of plants per
system would be required to take more or fewer samples than under the
plant-based approach. EPA used the median number of plants in a given
size category as the primary basis for establishing the number of
monitoring locations for the population-based approach.
EPA adjusted the number of sampling locations for systems in
population sizes 25,000 to 49,999, 100,000-499,999, and greater than
1,500,000 to provide a more even upward trend in proportion to
population increase. Consistent with the plant-based approach, ground
water systems serving 10,000 people or greater would be required to
sample at approximately \1/3\ to \1/2\ the frequency required for
surface water systems under the population-based approach.
EPA suggests that the monitoring frequencies for the IDSE and Stage
2B compliance proposed for consecutive systems that purchase all of
their finished water year-round (as presented in Tables V-4 and V-6)
are appropriate for all systems if a population-based approach were
used in lieu of a plant-based approach in the final rule. EPA believes
that the population-based approach would ensure more equal and rational
monitoring requirements among systems serving similar populations than
the plant-based approach does, while providing generally improved
representation of DBP occurrence throughout the distribution system.
Such an approach would simplify implementation and reduce transactional
costs to States by facilitating determination of the number of sampling
locations.
To further evaluate the potential implications of monitoring under
the population-based approach, EPA has prepared an economic analysis
addressing monitoring impacts using the population-based approach
(Economic Analysis for the Stage 2 DBPR, EPA 2003i) and guidance on how
plant-based monitoring requirements would be affected if a population-
based approach were used instead (Draft IDSE Guidance Manual, EPA
2003j).
EPA requests comments on alternative DBP monitoring requirements
that are population-based versus plant-based; specifically on the
merits of a population-based monitoring approach for all systems for
the purpose of addressing the issues raised in this section.
Specifically:

--Should alternative system size categories be specified under the
suggested population-based approach?
--What potential issues might be unique for a population-based
monitoring approach and how might they be addressed?
--Should alternative numbers of monitoring locations or frequencies be
required in the IDSE or for Stage 2B monitoring?
--Are reduced monitoring requirements adequate to ensure continued
protection relative to the MCL?
--What are the transition costs and issues associated with moving from
a plant-based to a population based approach and how might they be
addressed?

J. Compliance Schedules

1. What is EPA Proposing?
Today's proposed rule establishes compliance deadlines for public
water systems to implement the requirements in this rulemaking. EPA is
proposing a phased strategy for MCLs and simultaneous compliance with
the LT2ESWTR consistent with the recommendation of the M-DBP Advisory
Committee and to comply with SDWA requirements for risk balancing.
Central to the determination of these deadlines is the principle of
simultaneous compliance between the Stage 2 DBPR and the LT2ESWTR,
which will ensure continued microbial protection as systems implement
changes to decrease DBP levels and minimize risk-risk tradeoffs.
IDSE schedule. Subpart H and ground water systems covered by
today's proposed rule that serve a population of 10,000 or more must
submit the results of their IDSE to the primacy agency two years after
rule promulgation. In addition, wholesale or consecutive systems
serving fewer than 10,000 that are part of a combined distribution
system with at least one system serving £=10,000 must meet
this same schedule. These systems must begin IDSE monitoring early
enough to collect and analyze 12 months of data and prepare an IDSE
report, which includes recommendations for Stage 2B monitoring
locations (see section V.H). Subpart H and ground water systems covered
by today's proposed rule that serve a population of fewer than 10,000
(except those noted before) must submit the results of their IDSE to
the primacy agency four years after rule promulgation. These systems
must begin IDSE monitoring early enough to collect and analyze the data
and prepare the IDSE report.
Stage 2A schedule. All systems must comply with the Stage 2A MCLs
for TTHM and HAA5 three years after rule promulgation.
Stage 2B schedule. Systems required to submit an IDSE report due
two years after the rule is promulgated must comply with Stage 2B six
years after rule promulgation. Subpart H systems required to submit
IDSE reports four years after rule promulgation and required to do
Cryptosporidium monitoring under the LT2ESWTR must comply with Stage 2B
8.5 years after rule promulgation. Small systems not required to
Cryptosporidium monitoring must be in compliance with Stage 2B 7.5
years after rule promulgation. Figure V-2 contains several examples of
how to determine IDSE and Stage 2B compliance dates.

Figure V-2. Schedule Examples
------------------------------------------------------------------------

-------------------------------------------------------------------------
--Wholesale system (pop. 64,000) with three consecutive systems (pops.
21,000; 15,000; 5,000):
--IDSE report due for all systems two years after promulgation since
wholesale system serves at least 10,000
--Stage 2B compliance beginning six years after promulgation for all
systems
--Wholesale system (pop. 4,000) with three consecutive systems (pops.
21,000; 5,000; 5,000):
--IDSE report due for all systems two years after promulgation since
one consecutive system in combined distribution system serves at
least 10,000
--Stage 2B compliance beginning six years after promulgation for all
systems
--Wholesale system (pop. 4,000) with three consecutive systems (pops.
8,000; 5,000; 5,000):
--IDSE report due for all systems four years after promulgation
since no system in combined distribution system exceeds 10,000
(even though total population exceeds 10,000)
--Stage 2B compliance beginning 7.5 years after promulgation if no
Cryptosporidium monitoring under the LT2ESWTR is required or
beginning 8.5 years after promulgation if Cryptosporidium
monitoring under the LT2ESWTR is required
------------------------------------------------------------------------

[[Page 49606]]

2. How Did EPA Develop This Proposal?
EPA is proposing provisions for simultaneous rule compliance with
the LT2ESWTR to maintain a balance between DBP and microbial risks.
Simultaneous compliance was mandated by the 1996 SDWA Amendments which
require that EPA ``minimize the overall risk of adverse health effects
by balancing the risk from the contaminant and the risk from other
contaminants, the concentrations of which may be affected by the use of
a treatment technique or process that would be employed to attain the
maximum contaminant level'' (Sec. 1412(b)(5)(B)(i)).
If systems were required to comply with the Stage 2 DBPR prior to
the LT2ESWTR, systems could lower their disinfectant dose or switch to
a less effective disinfectant in an attempt to decrease DBP levels.
This practice could leave segments of the population exposed to greater
microbial risks. Therefore, simultaneous compliance was a consensus
recommendation of the Stage 2 M-DBP Advisory Committee to ensure that
systems would not compromise microbial protection while attempting to
meet more stringent DBP requirements.
The Advisory Committee supported the Initial Distribution System
Evaluation, as discussed in section V.H, and EPA is proposing an IDSE
schedule consistent with the Advisory Committee's recommendations, in
which systems are required to submit their IDSE reports to the State
either two or to four years following rule promulgation. The Advisory
Committee recommended this to allow enough time for the State to review
(and revise, if necessary) systems' recommendations for Stage 2B
monitoring locations and to allow systems three years after completion
of the State review to comply with Stage 2B MCLs as LRAAs at Stage 2B
monitoring locations.
This schedule requires systems serving £=10,000 people
and smaller wholesale and consecutive systems that are part of a
combined distribution system that includes at least one system serving
£=10,000 to complete IDSE monitoring and prepare and submit
the IDSE report two years after the rule is finalized. This requirement
for wholesale systems and consecutive systems serving fewer than 10,000
that are part of a combined distribution system with at least one
system serving at least 10,000 to conduct an ``early IDSE'' allows the
wholesale system to be aware of compliance challenges facing the
consecutive system and to implement treatment plant capital and
operational improvements as necessary to ensure compliance. The
Advisory Committee and EPA both recognized that DBPs, once formed, are
difficult to remove and are generally best addressed by treatment plant
improvements.
While this schedule allows for systems to have the three years to
comply with Stage 2B following State review of the IDSE report, it
begins prior to States being required to obtain primacy to implement
the IDSE. States have two years from promulgation to adopt and
implement new regulations and may request a two year extension. While
EPA is preparing to support implementation of those IDSE requirements
that must be completed prior to States achieving primacy, several
States have expressed concern about EPA providing guidance and
reviewing reports from systems that the State has permitted, inspected,
and worked with for a long time. These States believe that their
familiarity with the systems enables them to make the best decisions to
implement the rule and protect public health.
As specific rule requirements were developed and implementation
schedules and resource burdens determined, States also expressed
concerns about the challenges that early implementation posed. In
response to these concerns, EPA has developed several alternatives to
the IDSE schedule and provisions that may meet the goals of the IDSE,
but allow for greater State involvement, lower implementation burden,
and no delay of the public health protection assured by compliance with
Stage 2B.
The first, the ``Alternative IDSE'' option, would delay the
schedule for each IDSE requirement for two years. Since the compliance
date for Stage 2B would not be delayed, systems would need to implement
changes necessary for compliance on a much shorter schedule.
The second, the ``Concurrent Compliance Monitoring'' option, would
eliminate the IDSE but require compliance monitoring at an increased
number of sites during the first year of compliance monitoring as a way
to identify sites with high DBP levels. This option would reduce
government oversight and management and, as with other rules, leave
compliance determinations and preparations to individual systems (with
guidance available from States). In addition to compliance monitoring
at Stage 1 DBPR compliance monitoring sites during the first year under
Stage 2B, systems would also monitor at additional compliance
monitoring sites equal in number to the IDSE requirement and selected
using the same criteria that systems use to select IDSE monitoring
sites. Following one year of concurrent compliance monitoring, the
system would select routine Stage 2B compliance monitoring locations
using a protocol similar to the one used to recommend Stage 2B
compliance monitoring locations in the IDSE report.
Neither alternative would extend the compliance dates for either
Stage 2A or Stage 2B. As with the proposed IDSE, systems would be
eligible for the 40/30 certification approach if all TTHM and HAA5
compliance monitoring results in the two years prior to the effective
date were below 0.040 mg/L and 0.030 mg/L, respectively. States would
be able to grant very small system waivers to systems serving <500 with
a State finding that Stage 1 DBPR compliance monitoring locations sites
are adequate to represent both high TTHM and high HAA5 concentrations.
Table V-11 contains a comparison of the proposed IDSE schedule and the
schedules for the alternatives.

[[Page 49607]]

Table V-11.--Comparison of IDSE and IDSE Alternative Schedules
[Dates in italics are not in today's proposed rule, but reflect EPA's recommendation and guidance]
----------------------------------------------------------------------------------------------------------------
``Alternative IDSE'' ``Concurrent compliance
Requirement \1\ Today's proposal option monitoring'' option
----------------------------------------------------------------------------------------------------------------
IDSE start date for systems 0.5 years after 2.5 years after Requirement is for system
£=10,000. publication. publication to conduct concurrent
IDSE start date for systems <10,000 2.5 years after 4.5 years after compliance monitoring
IDSE report due for systems publication. publication (generally equal to
£=10,000. 2 years after 4 years after number of samples
IDSE report due for systems <10,000 publication. publication required under Stage 1
State review of IDSE report 4 years after 6 years after plus number under IDSE)
complete for systems publication. publication during first year of
£=10,000. 3 years after 5 years after compliance monitoring.
State review of IDSE report publication. publication Based on results in first
complete for systems <10,000. 4.5 years after 6.5 years after year, system would
publication. publication identify routine
compliance monitoring
locations using a
procedure similar to that
in IDSE report and begin
routine monitoring.
Stage 2B compliance for systems 6 years after publication \2\
£=10,000.
Stage 2B compliance for systems 7.5 years after publication if system is not required to conduct
<10,000. Cryptosporidium monitoring; 8.5 years after publication if system required
to conduct Cryptosporidium monitoring \2\
----------------------------------------------------------------------------------------------------------------
\1\ Systems serving £=10,000 also include wholesale systems and consecutive systems serving <10,000
that are part of a combined distribution system in which at least one system serves £=10,000.
\2\ State may grant up to two additional years for capital improvements necessary to comply.

3. Request for Comments
EPA requests comments on today's proposed compliance schedules.
Specifically:

--Should EPA promulgate an alternative approach to the IDSE recommended
in section V.H. that achieves the same goal of identifying Stage 2B
compliance monitoring locations and does not delay compliance with
Stage 2B MCLs, but allows for the States to receive primacy and be more
involved in IDSE implementation? Do either the ``Alternative IDSE''
option or the ``Concurrent Compliance Monitoring'' option achieve this
goal? Does one achieve the goal better than the other? Why? Are there
either changes to these alternatives or other alternatives not
presented that achieve this goal?
--Should EPA allow small consecutive systems to meet Stage 2B
compliance deadlines corresponding to their size (and later than the
deadlines for their wholesale system) provided they complete their IDSE
on the same schedule as the wholesale system and provided their water
quality does not affect the water quality of any other system?

K. Public Notice Requirements

1. What is EPA Proposing?
SDWA section 1414(c) requires PWSs to provide notice to their
customers for certain violations or in other circumstances. EPA's
public notification rule was published on May 4, 2000 (65 FR 25982),
and is codified at 40 CFR 141.201-141.210 (Subpart Q). Today's proposal
does not alter the existing TTHM and HAA5 health effects language that
is required in most public notices under Subpart Q. Because of the
uncertainties in the health data discussed in section III of today's
document, EPA is not proposing to include information about
reproductive and developmental health effects in public notices at this
time.
2. Request for Comments
EPA requests comment on the proposed public notification
requirements, including whether information about the possible
reproductive or fetal development effects that may be associated with
high levels of DBPs should be provided.

L. Variances and Exemptions

States may grant variances in accordance with sections 1415(a) and
1415(e) of the SDWA and EPA's regulations. States may grant exemptions
in accordance with section 1416 of the SDWA and EPA's regulations.
1. Variances
The SDWA provides for two types of variances--general variances and
small system variances. Under section 1415(a)(1)(A) of the SDWA, a
State that has primary enforcement responsibility (primacy), or EPA as
the primacy agency, may grant general variances from MCLs to those
public water systems of any size that cannot comply with the MCLs
because of characteristics of the water sources. A variance may be
issued to a system on condition that the system install the best
technology, treatment techniques, or other means that EPA finds
available and based upon an evaluation satisfactory to the State that
indicates that alternative sources of water are not reasonably
available to the system. At the time this type of variance is granted,
the State must prescribe a compliance schedule and may require the
system to implement additional control measures. Furthermore, before
EPA or the State may grant a general variance, it must find that the
variance will not result in an unreasonable risk to health to the
public served by the public water system. In this proposed rule, EPA is
specifying BATs for general variances under section 1415(a) (see
section V.F).
Section 1415(e) authorizes the primacy agency to issue variances to
small public water systems (those serving fewer than 10,000 people)
where the primacy agent determines (1) that the system cannot afford to
comply with an MCL or treatment technique and (2) that the terms of the
variances will ensure adequate protection of human health (63 FR 1943-
57; USEPA 1998d). These variances may only be granted where EPA has
determined that there is no affordable compliance technology and has
identified a small system variance technology under section 1412(b)(15)
for the contaminant, system size and source water quality in question.
As discussed below, small system variances under section 1415(e) are
not available because EPA has determined that affordable compliance
technologies are available.
The 1996 Amendments to the SDWA identify three categories of small
public water systems that need to be addressed: (1) Those serving a
population of 3301-10,000; (2) those serving a population of 500-3300;
and (3) those serving a population of 25-499. The SDWA requires EPA to
make determinations of available compliance technologies and,

[[Page 49608]]

if needed, variance technologies for each size category. A compliance
technology is a technology that is affordable and that achieves
compliance with the MCL and/or treatment technique. Compliance
technologies can include point-of-entry or point-of-use treatment
units. Variance technologies are only specified for those system size/
source water quality combinations for which there are no listed
compliance technologies.
EPA has completed an analysis of the affordability of DBP control
technologies for each of the three size categories. Based on this
analysis, multiple affordable compliance technologies were found for
each of the three system sizes (USEPA 2003i) and therefore variance
technologies were not identified for any of the three size categories.
The analysis was consistent with the methodology used in the document
``National-Level Affordability Criteria Under the 1996 Amendments to
the Safe Drinking Water Act'' (USEPA 1998g) and the ``Variance
Technology Findings for Contaminants Regulated Before 1996'' (USEPA
1998h).
2. What Are the Affordable Treatment Technologies for Small Systems?
The treatment trains considered and predicted to be used in EPA's
compliance forecast for systems serving under 10,000 people, are listed
in Table V-12.

Table V-12.--Technologies Considered and Predicted To Be Used in
Compliance Technology Forecast for Small Systems \1\
------------------------------------------------------------------------
SW water plants GW water plants
------------------------------------------------------------------------
? Switching to chloramines as a ? Switching to
residual disinfectant. chloramines as a residual
? Chlorine dioxide (Not for disinfectant
systems serving fewer than 100 people). ? UV
? UV............................. ? Ozone (not for systems
? Ozone (not for systems serving serving fewer than 100 people)
fewer than 100 people). \2\
? Micro-filtration/Ultra- ? GAC20 \2\
Filtration \2\. ? Nanofiltration \2\
? GAC20 \2\......................
? GAC20 + Advanced disinfectants.
? Membranes (Micro-Filtration/
Ultra-Filtration + Nanofiltration).
------------------------------------------------------------------------
\1\ Based on exhibits 6.8a and 6.8b in Economic Analysis for the
proposed Stage 2 DBPR (USEPA 2003i)
\2\ Italicized technologies are those predicted to be used in the
compliance forecast.

The household costs for these technologies were compared against
the national-level affordability criteria to determine the affordable
treatment technologies. The Agency's national-level affordability
criteria were published in the August 6, 1998 Federal Register (USEPA
1998g). In this document, EPA discussed the procedure for affordable
treatment technology determinations for the contaminants regulated
before 1996.
The following section provides a description of how EPA derived the
national-level affordability criteria pertinent to this rule. First,
EPA calculated an ``affordability threshold'' (i.e., the total annual
household water bill that would be considered affordable). The total
annual water bill includes costs associated with water treatment, water
distribution, and operation of the water system. In developing the
threshold of 2.5% median household income, EPA considered the
percentage of median household income spent by an average household on
comparable goods and services and on cost comparisons with other risk
reduction activities for drinking water such as households purchasing
bottled water or a home treatment device. The complete rationale for
EPA's selection of 2.5% as the affordability threshold is described in
``Variance Technology Findings for Contaminants Regulated Before 1996''
(USEPA 1998h).
The Variance Technology Findings document also describes the
derivation of the baselines for median household income, annual water
bills, and annual household consumption. Data from the Community Water
System Survey (CWSS) were used to derive the annual water bills and
annual water usage values for each of the three small system size
categories. The data on zip codes were used with the 1990 Census data
on median household income to develop the median household income
values for each of the three small-system size categories. The median
household-income values used for the affordable technology
determinations are not based on the national median income. The value
for each size category is a national median income for communities
served by small water systems within that range. Table V-13 presents
the baseline values for each of the three small-system size categories.
Annual water bills are based on 1995 estimates (USEPA 1998h) and
adjusted upward for anticipated costs attributed to new drinking water
regulations since 1995, i.e., the IESWTR, Stage 1 DBPR, Filter Backwash
Recycling Rule, Arsenic Rule, LT1ESWTR, Public Notification Rule, and
Consumer Confidence Rule.\1\ Median household income estimates are
based on estimates made in 1995 (USEPA 1998h) and adjusted upward for
inflation to represent 2000 incomes (USEPA 2003i).
---------------------------------------------------------------------------

\1\ EPA is currently receiving input from a National Drinking
Water Advisory Council (NDWAC). This process is expected to conclude
in the fall of 2003 with a report that will be sent by the NDWAC.
EPA has also received a report from the Science Advisory Board's
Environmental Economics Advisory Committee on its review of the
national-level affordability criteria (USEPA 2002c). One of the
charges given to both groups was to evaluate the process used by EPA
to adjust the baseline water bills to account for costs attributable
to regulations promulgated after 1996. Because the Stage 2 DBPR
affordability analysis is being conducted before EPA can complete a
comprehensive reassessment of affordability, today's estimate for
the increase to the average water bill to account for regulations
after 1996 reflects existing Agency affordability criteria and
methodology. This estimate may change in the future.

[[Page 49609]]

Table V-13.--Baseline Values for Small Systems Categories and Available Expenditure Margin for Affordable
Technology Determinations
----------------------------------------------------------------------------------------------------------------
Annual HH Available
consumption Median HH 2.5% median Current annual expenditure
System size category (pop. served) (1000 gallons/ income HH income(s) water bills ($/ margin ($/hh/
yr) ($) yr) year)
----------------------------------------------------------------------------------------------------------------
25-500.............................. 72 35,148 878 290 588
501-3,300........................... 74 30,893 772 230 542
3,301-10,000........................ 77 31,559 789 219 570
----------------------------------------------------------------------------------------------------------------

For each size category, the threshold value was determined by
multiplying the median household income by 2.5 percent. The annual
household water bills were subtracted from this value to obtain the
available expenditure margin. Projected treatment costs were compared
against the available expenditure margin to determine if there were
affordable compliance technologies for each size category. The
available expenditure margin for the three size categories is presented
in Table V-13.
The size categories specified in SDWA for affordable technology
determinations are different from the size categories typically used by
EPA in the Economic Analysis. A weighted average procedure was used to
derive design and average flows for the 25-500 category using design
and average flows from the 25-100 and 101-500 categories. A similar
approach was used to derive design and average flows from the 501-1000
and 1001-3300 categories for the 501-3300 category. The Variance
Technology Findings document (USEPA 1998h) describes this procedure in
more detail. Table V-14a lists the design and average flows for the
three size categories.

Table V-14a.--Design and Average Daily Flows Used for Affordable
Technology Determinations
------------------------------------------------------------------------
Design flow Average flow
System size category (population served) (mgd) (mgd)
------------------------------------------------------------------------
25-500.................................. 0.058 0.015
501-3,300............................... 0.50 0.17
3,301-10,000............................ 1.8 0.70
------------------------------------------------------------------------

Capital and operating and maintenance costs were derived for each
treatment technology used in the compliance forecast for small systems
using the flows listed previously and the cost equations in the
Technology and Cost Document (USEPA 2003k). Capital costs were
amortized using the 7 percent interest rate preferred by Office of
Management and Budget (OMB) for benefit-cost analyses of government
programs and regulations rather than a 3 percent interest rate.
The annual system treatment cost in dollars per year was converted
into a rate increase using the average daily flow. The annual water
consumption values listed in Table V-13 were multiplied by 1.15 to
account for water lost due to leaks. Since the water lost to leaks is
not billed, the water bills for the actual water used were adjusted to
cover this lost water by increasing the household consumption. The rate
increase in dollars per thousand gallons used was multiplied by the
adjusted annual consumption to determine the annual cost increase for
the household for each treatment technology.
With very few exceptions, the household costs for all predicted
compliance technologies in Table V-12 are below the available
expenditure margin. The only technology that was predicted to be used
in the compliance forecast for the Stage 2 DBPR and that costs slightly
more than the available expenditure margin is GAC20 (240 day carbon
replacement) with advanced disinfectants for systems serving 500 people
or fewer. As shown in the Economic Analysis (USEPA 2003i), 13 systems
(less than 1 percent) among systems serving fewer than 500 people are
predicted to use GAC20 with advanced disinfection to comply with the
proposed Stage 2 DBPR. However, alternate affordable technologies are
available. Thus, EPA believes that compliance by these systems will be
affordable. In some cases, the compliance data for these systems under
the Stage 2 DBPR is the same as under the Stage 1 DBPR (because many
systems serving fewer than 500 people will have the same single
sampling site under both rules); these systems will have already
installed the necessary compliance technology to comply with the Stage
1 DBPR. It is also possible that less costly technologies such as those
for which percentage use caps were set in the decision tree may
actually be used to achieve compliance (e.g., chloramines, UV).
As shown in Table V-14b, the cost model (USEPA 2003i) predicts that
households served by very small systems will experience household cost
increases greater than the available expenditure margins as a result of
adding advanced technology for the Stage 2 DBPR. This prediction is
probably overestimated because small systems have other compliance
alternatives available to them besides adding treatment. For example,
some of these systems currently may be operated on a part-time basis;
therefore, they may be able to modify the current operational schedule
or use excessive capacity to avoid installing a costly technology to
comply with the Stage 2 DBPR. The system also may identify another
water source that has lower TTHM and HAA5 precursor levels. Systems
that can identify such an alternate water source may not have to treat
that new source water as intensely as their current source, resulting
in lower treatment costs. Systems may elect to connect to a neighboring
water system. While connecting to another system may not be feasible
for some remote systems, EPA estimates that more than 22 percent of all
small water systems are located within metropolitan regions (USEPA
2000c) where distances between neighboring systems will not present a
prohibitive barrier. More discussion of household cost increases is
presented in a later section (Section VII) and the Economic Analysis
(USEPA 2003i).

[[Page 49610]]
[GRAPHIC]
[TIFF OMITTED]
TP18AU03.009

EPA is currently reviewing its national-level affordability
criteria, and has solicited recommendations from both the NDWAC and the
SAB as part of this review. If the national-level affordability
criteria are revised prior to promulgation of the final Stage 2 DBPR,
EPA may reevaluate the affordability of the identified small system
compliance technologies based on the revised criteria and may revise
its determination of whether to list any variance technologies as a
result. EPA requests comment on the application of its affordability
criteria in this rulemaking and on its determination that there are
affordable small system compliance technologies for all three statutory
small system size categories.

M. Requirements for Systems To Use Qualified Operators

EPA believes that systems that must make treatment changes to
comply with requirements to reduce microbiological risks and risks from
disinfectants and disinfection byproducts should be operated by
personnel who are qualified to recognize and respond to problems.
Subpart H systems were required to be operated by qualified operators
under the SWTR (40 CFR 141.70). The Stage 1 DBPR added requirements for
all disinfected systems to be operated by qualified personnel who meet
the requirements specified by the State, which may differ based on
system size and type. The rule also required that States maintain a
register of qualified operators (40 CFR 141.130(c)). While the proposed
Stage 2 DBPR requirements do not supercede or modify the requirement
that disinfected systems be operated by qualified personnel, the Stage
2 DBPR re-emphasizes the important role that qualified operators play
in delivering safe drinking water to the public. States should also
review and modify, as required, their qualification standards to take
into account new technologies (e.g., ultraviolet (UV) disinfection) and
new compliance requirements (including simultaneous compliance and
consecutive system requirements).

N. System Reporting and Recordkeeping Requirements

1. Confirmation of Applicable Existing Requirements
Today's proposed Stage 2 DBPR, consistent with the current system
reporting regulations under 40 CFR 141.131, requires public water
systems to report monitoring data to States within ten days after the
end of the compliance period. In addition, systems are required to
submit the data required in Sec. 141.134. These data are required to
be submitted quarterly for any monitoring conducted quarterly or more
frequently, and within ten days of the end of the monitoring period for
less frequent monitoring.
2. Summary of Additional Reporting Requirements
EPA proposes that two years after rule promulgation, systems
serving 10,000 or more people (plus consecutive systems that are part
of a combined distribution system with a system serving at least
10,000) be required to report the results of their IDSE to their State,
unless the State has waived this requirement for systems serving fewer
than 500. Systems are also required to report to the State recommended
long-term (Stage 2B) compliance monitoring sites as part of the IDSE
report. While the IDSE options discussed in section V.J. would delay
the timing of this requirement, EPA believes that the burden would not
change.
Beginning three years after rule promulgation, systems must report
compliance with Stage 2A MCLs based on LRAAs (0.120 mg/L TTHM and 0.100
mg/HAA5), as well as continue to report compliance with 0.080 mg/L TTHM
and 0.060 mg/L HAA5 as RAAs. Systems must report compliance with the
Stage 2B TTHM and HAA5 MCLs (0.080 mg/L TTHM and 0.060 mg/L HAA5 as
LRAAs) according to the compliance schedules outlined in section V.J.
of today's proposal. Reporting for DBP monitoring, as described
previously, will remain generally consistent with current public water
system reporting requirements (Sec. 141.31 and Sec. 141.134); systems
will be required to calculate and report each LRAA (instead of the
system's RAA) and each individual monitoring result (as required under
the Stage 1 DBPR). Systems will also be required to consult with the
State about each peak excursion event no later than the next sanitary
survey for the system, as discussed in section V.E.
3. Request for Comment
EPA requests comment on all system reporting and recordkeeping
requirements.

O. Analytical Method Requirements

1. What Is EPA Proposing Today?
The Stage 2 DBPR proposed today does not add any new disinfectants
or disinfection byproducts to the list of contaminants currently
covered by MRDLs or MCLs. However, additional methods have become
available since the analytical methods in the Stage 1 DBPR were
promulgated (USEPA 1998c). EPA is proposing to add to 40 CFR 141.131
one method for chlorine dioxide and chlorite, one method for HAA5 which
can also be used to analyze for the regulated contaminant dalapon,
three methods for bromate, chlorite, and bromide, one method for
bromate only, and one method for total

[[Page 49611]]

organic carbon (TOC) and specific ultraviolet absorbance (SUVA). One of
the methods that is currently approved for bromate, chlorite, and
bromide can be used to determine chloride, fluoride, nitrate, nitrite,
orthophosphate, and sulfate, so EPA is proposing to add it as an
approved method for those contaminants in 40 CFR 141.23 and 40 CFR
143.4. EPA is also proposing to add the HAA5 method that includes
dalapon to 40 CFR 141.24 for dalapon compliance monitoring.
Several of the methods that were promulgated with the Stage 1 DBPR
have been included in publications that were issued after December
1998. EPA is proposing to approve the use of the recently published
versions of three methods for determining free, combined, and total
chlorine residuals, two methods for total chlorine only, one method for
free chlorine only, one method for chlorite and chlorine dioxide, one
method for chlorine dioxide only, one method for HAA5, three methods
for TOC and dissolved organic carbon (DOC), and one method for
ultraviolet absorption at 254nm (UV ₂₅₄). EPA is proposing
to update the citation for one method for bromate, chlorite, and
bromide.
EPA is also proposing to standardize the HAA5 sample holding times
and the bromate sample preservation procedure and holding time. EPA is
clarifying which methods are approved for magnesium hardness
determinations in 40 CFR 141.131 and 40 CFR 141.135.
Analytical methods that are proposed for approval or for which
changes are proposed in today's rule are summarized in Table V-15 and
are described in more detail later in this section.

Table V-15.--Analytical Methods Addressed in Today's Proposed Rule
----------------------------------------------------------------------------------------------------------------
Analyte EPA method Standard method 1 Other
----------------------------------------------------------------------------------------------------------------
Sec. 141.23
Fluoride....................... 300.1 .......................... .......................
Nitrate........................ 300.1 .......................... .......................
Nitrite........................ 300.1 .......................... .......................
Orthophosphate................. 300.1 .......................... .......................
Sec. 141.24
Dalapon........................ 552.3 .......................... .......................
Sec. 141.131--Disinfectants
Chlorine (free, combined, .......................... 4500-Cl D
total).
.......................... 4500-Cl F
.......................... 4500-Cl G
(total) .......................... 4500-Cl E
.......................... 4500-Cl I
(free) .......................... 4500-Cl H
Chlorine Dioxide............... 327.0 4500-ClO ₂ D
4500-ClO ₂ E
Sec. 141.131--Disinfection
Byproducts
HAA5........................... 552.1 2 6251 B 2 .......................
552.3
Bromate........................ 300.1 3 .......................... ASTM D 6581-00
317.0 Revision 2
321,8 4
326.0
Chlorite (monthly or daily).... 300.1 3 .......................... ASTM D 6581-00
317.0 Revision 2
326.0
(daily)........................ 327.0 4500-ClO ₂ E .......................
Sec. 141.131--Other
parameters
Bromide........................ 300.1 3 .......................... ASTM D 6581-00
317.0 Revision 2
326.0
TOC/DOC........................ 415.3 5310 B
5310 C
5310 D
UV ₂₅₄......................... 415.3 5910 B .......................
SUVA........................... 415.3 .......................... .......................
Sec. 143.4
Chloride....................... 300.1 .......................... .......................
Sulfate........................ 300.1 .......................... .......................
----------------------------------------------------------------------------------------------------------------
1 EPA is proposing to cite both the 20th edition and the 2003 On-Line Version of Standard Methods for the
Examination of Water and Waste Water in addition to the currently cited 19th editions for all methods listed
in this column with the exception of 4500-ClO₂ D for chlorine dioxide which is not available in the 2003 On-
Line Version.
2 EPA is proposing to change the sample holding time to 14 days.
3 EPA is proposing to update the citation.
4 EPA is proposing that samples be preserved with 50 mg ethylenediamine/L and analyzed within 28 days.

2. How Was This Proposal Developed?
EPA evaluated the performance of the new methods for their
applicability to compliance monitoring. The primary purpose of this
evaluation was to determine if the new methods provide data of
comparable or better quality than the methods that are currently
approved. Methods currently approved for DBPs were also examined to
determine applicability to other regulated contaminants.
EPA reviewed the new publications of methods from consensus
organizations such as Standard Methods and American Society for Testing
and Materials (ASTM). As a result, EPA identified one new method from
ASTM

[[Page 49612]]

which is suitable for compliance monitoring. EPA also determined that
the newer editions of Standard Methods did not change the individual
methods approved under the Stage 1 DBPR.
3. Which New Methods Are Proposed for Approval?
a. EPA Method 327.0 for chlorine dioxide and chlorite. EPA is
proposing to add a new method for the measurement of chlorine dioxide
residuals and daily chlorite concentrations. EPA Method 327.0 (USEPA
2003q) is an enzymatic/spectrophotometric method in which a total
chlorine dioxide plus chlorite concentration is determined in an
unsparged sample and the chlorite concentration is determined in a
sparged sample. The chlorine dioxide concentration is then calculated
by subtracting the chlorite concentration from the total.
The pH of the samples (sparged and unsparged) and blank are
adjusted to 6.0 with a citric acid/glycine buffer. The chromophore
Lissamine Green B (LGB) and the enzyme horseradish peroxidase are
added. The enzyme reacts with the chlorite in the sample to form
chlorine dioxide which then reacts with the chromophore LGB to reduce
the absorbance at 633nm of the sample. The absorbance of the samples
and blank are determined spectrophotometrically. The difference in
absorbance between the samples and the blank is proportional to the
chlorite and total chlorine dioxide/chlorite concentrations in the
samples.
EPA Method 327.0 offers advantages over the currently approved
methods in that it is not subject to positive interferences from other
chlorine species and it is easier to use.
The single laboratory detection limits presented in the method are
0.08-0.11 mg/L for chlorite and 0.04-0.16 mg/L for chlorine dioxide.
The detection limits are based on the analyses of sets of seven
replicates of reagent water that were fortified with low concentrations
of chlorite with and without the presence of chlorine dioxide and low
concentrations of chlorine dioxide with and without the presence of
chlorite. The standard deviation of the mean concentration for each set
of samples was calculated and multiplied by the student's t-value at
99% confidence and n-1 degrees of freedom (3.143 for 7 replicates) to
determine the detection limit. The accuracy reported in the method for
laboratory fortified blanks at concentrations of 0.2-1.0 mg/L is 103-
118 % for chlorite and 102-124 % for chlorine dioxide with relative
standard deviations between 2.9 and 16 %. Replicate analyses of
drinking water samples from surface and ground water sources fortified
at concentrations of approximately 1 and 2 mg/L chlorite and chlorine
dioxide showed average recoveries of 91-110 % with relative standard
deviations of 1-9 %.
EPA is proposing to approve EPA Method 327.0 as an additional
method for monitoring chlorine dioxide and for making the daily
determination of chlorite at the entry point to the distribution
system. It will provide water systems with additional flexibility in
monitoring the application of chlorine dioxide. EPA believes that many
water plant operators will prefer the new method over the currently
approved methods due to its ease of use.
b. EPA Method 552.3 for HAA5 and dalapon. EPA is proposing to add a
new method (EPA Method 552.3) for HAA5 that provides comparable
sensitivity, accuracy, and precision to the previously approved
methods. EPA Method 552.3 (USEPA 2003p) has the added benefit of
allowing laboratories to more easily measure four additional haloacetic
acids (bromochloroacetic acid, bromodichloroacetic acid,
chlorodibromoacetic acid, and tribromoacetic acid) at the same time the
HAA5 compounds are being measured, without compromising the quality of
data for the HAA5 compounds. Of the currently approved methods for
HAA5, only EPA Method 552.2 (USEPA 1995) provides method performance
data for all of these additional compounds, but the reaction conditions
must be carefully controlled. EPA believes that analyses for these
additional HAAs can be accomplished more easily without compromising
the quality of data for the HAA5 compounds by using EPA Method 552.3.
EPA Method 552.3 for HAA5, other haloacetic acids, and the
regulated contaminant dalapon allows two extraction options. The first
option involves an acidic extraction with methyl tertiary butyl ether
(MTBE) which is the same solvent used in the currently approved HAA5
methods. The analytes (HAA5, other HAAs, and dalapon) are then
converted to their methyl esters by the addition of acidic methanol to
the extract followed by heating. The amount of acidic methanol that is
added to the extract is increased in the new method resulting in
increased methylation efficiency for some of the analytes. The
increased methylation efficiency is significant for the additional HAAs
and thus provides greater sensitivity, precision, and accuracy for them
when compared to EPA Method 552.2. The acidic extract is neutralized
with a saturated solution of sodium bicarbonate and the target analytes
are identified and measured by gas chromatography using electron
capture detection (GC/ECD).
The second option in the new EPA Method 552.3 involves an acidic
extraction with tertiary amyl methyl ether (TAME). The HAAs are then
converted to their methyl esters by the addition of acidic methanol to
the extract followed by heating. The use of TAME instead of MTBE as the
extraction solvent allows the use of a higher temperature during the
methylation process. This increases the methylation efficiency and thus
provides significant increases in sensitivity, precision, and accuracy
for the additional HAAs. The acidic extract is neutralized with a
saturated solution of sodium bicarbonate and the target analytes are
identified and measured by gas chromatography using electron capture
detection (GC/ECD).
The performance of EPA Method 552.3 is comparable to the currently
approved methods for determining the HAA5 analytes. A comparison of the
performance of EPA Method 552.3 to the currently approved HAA5 methods
is shown in Table V-16. The data are taken from the individual methods,
so the precision, accuracy, and detection data were not generated using
the same samples or by the same laboratory.

Table V-16.--Performance of Haloacetic Acid Methods
----------------------------------------------------------------------------------------------------------------
QC Parameter MCAA DCAA TCAA MBAA DBAA
----------------------------------------------------------------------------------------------------------------
Precision (Max %RSD in fortified drinking water
samples) \1\
EPA 552.1...................................... 15 14 28 11 7
EPA 552.2...................................... 13 6 15 6 5
EPA 552.3 (MTBE option)........................ 6 4 1 4 5
EPA 552.3 (TAME option)........................ 10 4 2 4 5
SM 6251 B...................................... 8 7 6 8 7

[[Page 49613]]

Accuracy (Range of % Recoveries in fortified
drinking water samples) \2\
EPA 552.1...................................... 76-100 75-126 56-106 86-97 94-103
EPA 552.2...................................... 84-97 96-105 62-82 86-100 72-112
EPA 552.3 (MTBE option)........................ 98-126 96-103 89-100 99-113 101-111
EPA 552.3 (TAME option)........................ 97-131 97-107 89-103 99 101-105
SM 6251 B...................................... 99-103 96-103 100-103 97-101 102
Detection Limit ([mu]g/L) \3\
EPA 552.1...................................... 0.21 0.45 0.07 0.24 0.09
EPA 552.2...................................... 0.27 0.24 0.08 0.20 0.07
EPA 552.3 (MTBE option)........................ 0.17 0.02 0.02 0.03 0.01
EPA 552.3 (TAME option)........................ 0.20 0.08 0.02 0.13 0.02
SM 6251 B...................................... 0.08 0.05 0.05 0.09 0.06
----------------------------------------------------------------------------------------------------------------
\1\ The highest relative standard deviation (%RSD) for replicate analyses of fortified drinking water samples as
shown in each method.
\2\ The range of recoveries reported for replicate analyses of fortified drinking water samples as shown in each
method.
\3\ The detection limit as determined by analyzing seven or more replicates of reagent water that is fortified
with low concentrations of the haloacetic acids. The standard deviation of the mean concentration for each
analyte is calculated and multiplied by the student's t-value at 99% confidence and n-1 degrees of freedom
(3.143 for 7 replicates).

Two of the currently approved HAA5 methods (EPA Methods 552.1
(USEPA 1992) and 552.2 (USEPA 1995)) are also approved for analyses of
water samples for the regulated contaminant dalapon, a synthetic
organic chemical. The new HAA5 method can also be used to determine
dalapon in drinking water. As shown in Table V-17, both solvent options
in EPA Method 552.3 provide comparable or better method performance
than the approved methods.

Table V-17.--Performance of Dalapon Methods
----------------------------------------------------------------------------------------------------------------
EPA 552.3
Dalapon performance characteristic EPA 552.1 EPA 552.2 -----------------------
MTBE TAME
----------------------------------------------------------------------------------------------------------------
Precision\1\ (% RSD).................................. 14 11 2 4
Accuracy\2\ (% Recovery).............................. 88-102 86-100 98-112 87-103
Detection Limit\3\ ([mu]g/L).......................... 0.32 0.12 0.02 0.14
----------------------------------------------------------------------------------------------------------------
\1\ The highest relative standard deviation (%RSD) for replicate analyses of fortified drinking water samples as
shown in each method.
\2\ The range of recoveries reported for replicate analyses of fortified drinking water samples as shown in each
method.
\3\ The detection limit as determined by analyzing seven or more replicates of reagent water that is fortified
with low concentrations of dalapon. The standard deviation of the mean dalapon concentration is calculated and
multiplied by the student's t-value at 99% confidence and n-1 degrees of freedom (3.143 for 7 replicates).

EPA is proposing to approve EPA Method 552.3 for dalapon (Sec.
141.24(e)(1)) in addition to HAA5 even though dalapon is not a
contaminant that is addressed in this proposed rule. EPA believes that
extending approval to all the regulated contaminants covered by the
method provides more flexibility to laboratories. It allows the
laboratories the option of reducing the number of methods that they
need to keep in operation for their clients, because the new method can
be used for dalapon and HAA5 compliance monitoring samples and for
determining the additional HAAs for non-regulatory purposes. EPA
recognizes that laboratories will probably not be determining dalapon
concentrations for compliance purposes in the same samples as used for
HAA5 compliance monitoring. However, EPA believes allowing the same
method to be used even if the samples are not the same is more cost
effective for laboratories, because switching between methods results
in increased analyst and instrument time. EPA is not proposing to
withdraw the other dalapon methods, because that would reduce
flexibility for the laboratories and place an unnecessary burden on
laboratories that do not need to use EPA Method 552.3.
c. ASTM D 6581-00 for bromate, chlorite, and bromide. ASTM Method D
6581-00 (ASTM 2002) for the determination of bromate, chlorite, and
bromide was adopted by ASTM in 2000. This method uses the same
procedures as EPA Method 300.1 (USEPA 2000l) (the method promulgated in
the Stage 1 DBPR) and thus is considered equivalent to the approved
method (Hautman et al. 2001). The ASTM method includes interlaboratory
study data that were not available when EPA Method 300.1 was published.
The study data demonstrate good precision and low bias for all
analytes.
Under section 12(d) of the National Technology Transfer and
Advancement Act, the Agency is directed to consider whether to use
voluntary consensus standards in its regulatory activities. ASTM Method
D 6581-00 is an acceptable consensus standard and it is published in
the 2001, 2002, and 2003 editions of The ASTM Annual Book of Standards.
EPA is proposing to approve ASTM Method D 6581-00 in order to provide
additional flexibility to laboratories. Any edition containing the
cited version may be used.
d. EPA Method 317.0 revision 2 for bromate, chlorite, and bromide.
EPA Method 317.0 Revision 2 (USEPA 2001d) is an extension of the
currently approved EPA Method 300.1 for bromate, chlorite, and bromide.
It uses the EPA Method 300.1 technology, but it adds a postcolumn
reactor that provides a more sensitive and specific analysis for
bromate than is obtained using EPA Method 300.1. As with EPA Method
300.1, the anions are separated by ion chromatography and detected
using a conductivity detector. (Bromate, chlorite, and bromide
concentrations determined by the conductivity detector are equivalent
to those measured using EPA Method 300.1.) After the sample

[[Page 49614]]

passes through the conductivity detector, it enters a postcolumn
reactor chamber in which o-dianisidine dihydrochloride (ODA) is added
to the sample. This compound forms a chromophore with the bromate that
is present in the sample and the chromophore concentration is
determined using a ultraviolet/visible (UV/Vis) absorbance detector.
There are several advantages of this method:
(1) Very few ions react with ODA to form compounds that are
detected by the UV/Vis detector. This makes the method less susceptible
to interferences for bromate.
(2) The UV/Vis detector is very sensitive to the chromophore, so
lower concentrations of bromate can be detected and quantitated.
(Bromate concentrations can be reliably quantitated as low as 1 [mu]g/L
using this detector versus 5 [mu]g/L for EPA Method 300.1.)
(3) Since the front part of the analysis is the same as EPA Method
300.1, bromate, chlorite, and bromide can be determined in the same
analysis.
The first version of this method, EPA Method 317.0 has been
evaluated in a multiple laboratory study (Wagner et al. 2001; Hautman
et al. 2001). The results from the study indicate high precision and
very low bias in data generated using this method. The interlaboratory
precision for bromate, chlorite, and bromide using the conductivity
detector and bromate using the UV/Vis detector are 12%, 4.2%, 6.9%, and
9.6% relative standard deviation (RSD), respectively. The
interlaboratory bias for bromate, chlorite, and bromide using the
conductivity detector and bromate using the UV/Vis detector are 0.35%,
-0.98%, -0.87%, and 4.8%, respectively. The average detection levels
for bromate, chlorite, and bromide using the conductivity detector and
bromate using the UV/Vis detector are 2.2, 1.6, 2.8, and 0.24 [mu]g/L,
respectively.
Subsequent to the interlaboratory study of EPA Method 317.0, a
problem with ODA was discovered. The purity of the reagent can vary
from lot to lot and this affects the performance of the method. EPA has
evaluated the method performance using ODA obtained from several
commercial sources and from different lots from the same supplier.
Based on that new information, EPA revised Method 317.0 to document how
to detect and correct problems that can result from a contaminated ODA
supply. The revised method is designated EPA Method 317.0 Revision 2.0
and this is the version that is being proposed today. The performance
of the revised method is identical to the original version.
EPA believes EPA Method 317.0 Revision 2.0 should be approved as an
additional method for bromate, chlorite, and bromide compliance
monitoring. EPA anticipates that water systems will prefer to have
their bromate samples analyzed by this new method, because it provides
higher quality data than the currently approved method when bromate
concentrations are below the MCL of 0.010 mg/L (10 [mu]g/L). Only a few
laboratories are currently performing analyses using the postcolumn
reactor technology included in the method, but the number is increasing
as more laboratories become aware of the advantages.
e. EPA Method 326.0 for bromate, chlorite, and bromide. EPA Method
326.0 (USEPA 2002a) is based on the procedure reported by Salhi and von
Gunten (1999) and uses an approach that is similar to EPA Method 317.0
Revision 2.0. The method involves the separation of the anions
(bromate, chlorite, and bromide) following the scheme outlined in EPA
Methods 300.1 and 317.0 Revision 2.0. (Bromate, chlorite, and bromide
data from the conductivity detector are equivalent to data generated
using EPA Method 300.1.) The eluent stream exiting the conductivity
detector is mixed with a postcolumn reagent consisting of an acidic
solution of potassium iodide with a catalytic concentration of
molybdenum (VI). Bromate reacts with the iodide to form triiodide which
is measured by its UV absorption at 352 nm.
EPA Method 326.0 has similar accuracy, precision, and sensitivity
for bromate compared to EPA Method 317.0 Revision 2.0. Thirty drinking
water samples fortified with 1-7 [mu]g bromate/L were analyzed using
both methods. Accuracy, expressed as % recovery, ranged from 78.0 to
129% for both methods and precision, expressed as % RSD ranged from 3.7
to 13.5% (Wagner et al. 2002). The detection limit of EPA Method 326.0
is 0.17 [mu]g/L as determined by analyzing seven or more replicates of
reagent water that is fortified with low concentrations of bromate. The
standard deviation of the mean bromate concentration is calculated and
multiplied by the student's t-value at 99% confidence and n-1 degrees
of freedom (3.143 for 7 replicates).
EPA is proposing EPA Method 326.0 as an additional method for
bromate, chlorite, and bromide compliance monitoring. It provides
higher quality bromate data than the currently approved EPA Method
300.1 when bromate concentrations are below 10 [mu]g/L. EPA anticipates
the number of laboratories using this method will increase as utilities
become aware of the method's sensitivity and begin to request it be
used for their samples.
f. EPA Method 321.8 for bromate. EPA is proposing to add EPA Method
321.8 (USEPA 2000d) specifically for bromate compliance monitoring. It
involves an ion chromatograph coupled to an inductively coupled plasma
mass spectrometer (IC/ICP-MS). The ion chromatograph separates bromate
from other ions present in the sample and then bromate is detected and
quantitated by the ICP-MS. Mass 79 is used for quantitation while mass
81 provides isotope ratio information that can be used to screen for
potential polyatomic interferences. The advantage of this method is
that it is very specific and sensitive to bromate. The single
laboratory detection limit presented in the method is 0.3 [mu]g/L. The
average accuracy reported in the method for laboratory fortified blanks
is 99.8% recovery with a three sigma control limit of 10.2%. Average
accuracy and precision in fortified drinking water samples are reported
as 97.8% recovery and 2.9% relative standard deviation, respectively.
During the Information Collection Rule, thirty-three samples were
analyzed by this method in addition to the selective anion
concentration (SAC) method used by EPA for the low-level bromate
analyses. EPA Method 321.8 provided comparable data to that generated
by the SAC method (Fair 2002).
EPA Method 321.8 has undergone second laboratory validation (Day et
al. 2001) and the results indicate the method can be successfully
performed in non-EPA laboratories. The calculated detection limit
determined by the second laboratory is 0.4 [mu]g/L. The average
accuracy achieved for laboratory fortified blanks at 5 [mu]g/L is 93%
recovery with a relative standard deviation of 8.9%. Average accuracy
and precision in fortified drinking water samples are reported as 101%
recovery and 9% relative standard deviation, respectively.
The IC/ICP-MS instrumentation used in EPA Method 321.8 is a new
technology in the drinking water laboratory community. Even though the
technology is not yet widely used, EPA believes that approving this new
method will provide laboratories with the flexibility to adopt the new
technology if they have additional applications for it. The
instrumentation is especially promising in the area of trace metal
speciation. Laboratories that are performing that type of analysis
would find it very useful to also be able

[[Page 49615]]

to perform bromate compliance monitoring analyses by EPA Method 321.8.
EPA believes that advances in analytical technology should be
encouraged when they provide additional options for obtaining accurate
and precise data for compliance monitoring. Approval of this method
would not require laboratories to adopt the new technology; it strictly
offers the choice for laboratories that would like to use the latest
technology.
EPA is proposing to add sample collection and holding time
requirement to EPA Method 321.8. The current method does not address
the potential for changes in bromate concentrations after the sample is
collected as a result of reactions with hypobromous acid/hypobromite
ion. Hypobromous acid/hypobromite ion are intermediates formed as
byproducts of the reaction of either ozone or hypochlorous acid/
hypochlorite ion with bromide ion. If not removed from the sample
matrix, further reactions may form bromate ion. The reactions can be
prevented by adding 50 mg of ethylenediamine (EDA)/L of sample. This is
the preservation technique specified in the other methods both approved
and proposed for bromate compliance analyses. The fortified drinking
water samples analyzed in the second laboratory validation study of EPA
Method 321.8 (Day et al. 2001) and the Information Collection Rule
samples that were analyzed using the SAC method and EPA Method 321.8
were preserved with EDA, thus demonstrating that EDA can be used in
samples analyzed by IC/ICP-MS. EPA believes that adding this sample
preservation requirement to EPA Method 321.8 will help ensure sample
integrity. It will also simplify the sampling protocols that water
systems must follow, because all sampling for bromate, regardless of
the method employed to analyze the sample, will require the same sample
preservation technique.
EPA Method 321.8 does not include information concerning how long a
sample may be stored prior to analysis. EPA is proposing to specify a
maximum of 28 days for the sample holding time. This would make the
method consistent with the other bromate methods proposed today and the
method that is currently approved.
g. EPA 415.3 for TOC and SUVA (DOC and UV₂₅₄). Today's
rule proposes to add EPA Method 415.3 (USEPA 2003r) as an approved
method for TOC and SUVA. The Stage 1 DBPR included three Standard
Methods for TOC and one method for UV₂₅₄. Additional quality
control (QC) requirements were included for these measurements, because
the methods did not contain the necessary criteria. The rule included
instructions for calculating SUVA based on UV₂₅₄ and DOC
analyses. The new EPA Method 415.3 includes the additional QC necessary
to achieve reliable determinations for TOC, DOC, and UV₂₅₄.
It describes a procedure for removing inorganic carbon from the sample
prior to the organic carbon analysis. The method uses the same
technologies as already approved. The advantage of this new method is
that it documents the precision and accuracy that can be expected when
proper QC procedures are implemented and it places all the necessary
information for SUVA in one place.
EPA Method 415.3 provides sensitivity, precision and accuracy data
for TOC and DOC measured using five different technologies:
(1) Catalyzed 680[deg]C combustion oxidation of organic carbon to
carbon dioxide (CO₂) followed by nondispersive infrared
detection (NDIR).
(2) High temperature (700 to 1100[deg]C) combustion oxidation
followed by NDIR.
(3) Elevated temperature (95-100[deg]C) catalyzed persulfate
digestion of organic carbon to CO₂ followed by NDIR.
(4) UV catalyzed persulfate digestion followed by NDIR.
(5) UV catalyzed persulfate digestion followed by membrane
permeation into a conductivity detector.

These technologies are included in the currently approved Standard
Methods 5310 B and 5310 C (APHA, 1996). The new method indicates these
technologies can provide detection limits between 0.02 mg/L and 0.12
mg/L. Accuracy and precision data from analyses of fortified reagent
water and natural waters indicate the technologies can produce
acceptable data for determining compliance with the treatment technique
for control of disinfection byproduct precursors specified in Sec.
141.135. Seven natural waters were fortified with organic carbon from
potassium hydrogen phthalate and analyzed by each of the five
technologies. The average recoveries ranged from 97% to 103% for TOC
and 98% to 106% for DOC.
The method presents data from the analyses of seven different
waters and demonstrates that comparable analytical results are obtained
regardless of the technology used as long as all inorganic carbon is
removed from the sample prior to the analysis. The samples ranged in
concentration from 0.4 to 3.6 mg/L and the relative standard deviations
across the analyses ranged from 35% RSD (for the lowest concentration
sample) to <=13% RSD for the remainder of the samples.
EPA Method 415.3 includes a procedure to ensure that inorganic
carbon does not interfere with the organic carbon analyses. Since this
is critical to obtaining accurate organic carbon determinations, EPA is
proposing to add a requirement at Sec. Sec. 141.131(d)(3) and (4)(i)
to remove inorganic carbon prior to performing TOC or DOC analyses.
Laboratories will have the option of using the procedure described in
EPA Method 415.3 or verifying that the process used by their TOC
instrument adequately removes the inorganic carbon prior to the organic
carbon measurement. Determination of organic carbon by subtracting the
inorganic carbon from the total carbon is not acceptable for compliance
purposes, because the percentage of inorganic carbon is usually large
in relation to the organic carbon of the sample and the subtraction
process introduces a large potential for error.
The manufacturer of one of the instruments that was used during the
development of EPA Method 415.3 recommends that hydrochloric acid be
used to acidify TOC and DOC samples prior to analysis. EPA confirmed
that use of this acid is critical for proper operation of the
instrument. However, use of hydrochloric acid is in conflict with the
current regulation at Sec. Sec. 141.131(d)(3) and (4)(i) which specify
phosphoric or sulfuric acid. The type of acid used to preserve samples
and to treat the samples to remove inorganic carbon prior to the
organic carbon analysis should be based on the analytical method or the
instrument manufacturer's specification. Therefore, EPA is proposing to
remove the specification of acid type from Sec. Sec. 141.131(d)(3) and
(4)(i).
EPA Method 415.3 specifies that TOC samples be acid preserved at
the time of collection in order to prevent microbial degradation of the
organic carbon. This is consistent with the sampling instructions in
the currently approved methods (Standard Methods 5310 B, 5310 C, and
5310 D). EPA proposes to amend Sec. 141.131(d)(3) by removing the
phrase ``not to exceed 24 hours'' in the description of when samples
must be preserved, so that the rule is consistent with the method
specifications.
Analyses for both DOC and UV₂₅₄ are required for a SUVA
determination. The DOC measurement is identical to the TOC measurement
after the sample is filtered through a 0.45 [mu]m pore size filter. The
filtration step must be

[[Page 49616]]

performed using a prewashed filter in order to eliminate positive
interferences from material that can leach from improperly cleaned
filters. EPA Method 415.3 contains a description of how to properly
rinse the filters and how to verify that the filter blank is
acceptable. The method demonstrates that it is feasible to have a
filter blank with a DOC concentration <0.2 mg/L. The method also
provides performance data for DOC.
The UV₂₅₄ analysis that is part of the SUVA
determination is also described in EPA Method 415.3. As with the DOC
measurement, the UV₂₅₄ analysis is performed on a sample
that has been filtered through a prewashed 0.45 [mu]m pore size filter.
In addition to verifying that the filter blank is low enough, the
method also includes a spectrophotometer check procedure to ensure that
the spectrophotometer is operating properly.
4. What Additional Regulated Contaminants Can Be Monitored by Extending
Approval of EPA Method 300.1?
In addition to bromate, chlorite, and bromide, EPA Method 300.1
(USEPA 2000l) can also be used to determine chloride, fluoride,
nitrate, nitrite, orthophosphate, and sulfate in drinking water. A
comparison of the performance of EPA Method 300.1 to the currently
approved EPA Method 300.0 (USEPA 1993) is shown in Table V-18 and
demonstrates that EPA Method 300.1 provides comparable or better
precision, accuracy, and sensitivity for these contaminants based on
the single laboratory data presented in each method.

Table V-18.--Comparison of EPA Methods 300.0 and 300.1
----------------------------------------------------------------------------------------------------------------
QC parameter Chloride Fluoride Nitrate Nitrite Phosphate-P Sulfate
----------------------------------------------------------------------------------------------------------------
Precision (Max % RSD in fortified water samples) \1\
----------------------------------------------------------------------------------------------------------------
EPA 300.0......................... 5.7 18 4.8 3.6 3.5 7.1
EPA 300.1......................... 0.22 0.85 0.41 0.77 4.7 0.39
-----------------------------------
Accuracy (Range of % Recoveries in fortified water samples) \2\
----------------------------------------------------------------------------------------------------------------
EPA 300.0......................... 86-114 73-95 93-104 92-121 95-99 95-112
EPA 300.1......................... 93-98 80-89 88-96 72-87 61-92 89
-----------------------------------
Detection Limit (mg/L) \3\
----------------------------------------------------------------------------------------------------------------
EPA 300.0......................... 0.02 0.01 0.002 0.004 0.003 0.02
EPA 300.1......................... 0.004 0.009 0.008 0.001 0.019 0.019
----------------------------------------------------------------------------------------------------------------
\1\ The highest relative standard deviation (%RSD) reported in the method for replicate analyses of fortified
water samples in a single laboratory.
\2\ The range of recoveries reported for replicate analyses of fortified water samples in a single laboratory as
shown in the method.
\3\ The detection limit as determined by analyzing seven or more replicates of reagent water that is fortified
with low concentrations of the anions. The standard deviation of the mean concentration for each analyte is
calculated and multiplied by the student's t-value at 99% confidence and n-1 degrees of freedom (3.143 for 7
replicates).

EPA is proposing to extend approval of EPA Method 300.1 for
fluoride, nitrate, nitrite, and orthophosphate (Sec. 141.23(k)(1)) and
for chloride and sulfate (Sec. 143.4(b)) even though these
contaminants are not addressed in today's proposed rule. As discussed
before for dalapon, EPA believes that extending approval to all the
regulated contaminants covered in a method provides greater flexibility
to laboratories and allows them to reduce analytical costs. EPA
recognizes that laboratories will probably not be determining
concentrations of these non-DBP anions for compliance purposes in the
same samples as used for chlorite or bromate compliance monitoring.
However, EPA believes allowing the same method to be used even if the
samples are not the same is more cost effective for laboratories. EPA
is not proposing to withdraw any methods for the non-DBP anions,
because that would place an unnecessary burden on laboratories that do
not need to use EPA Method 300.1.
5. Which Methods in the 20th Edition and 2003 On-Line Version of
Standard Methods Are Proposed for Approval?
The Stage 1 DBPR approved eight methods (4500-Cl D, 4500-Cl F,
4500-Cl G, 4500-Cl E, 4500-Cl I, 4500-Cl H, 4500-ClO₂ D, and
4500-ClO₂ E) for determining disinfection residuals from the
19th edition of Standard Methods (APHA, 1995). Standard Methods 6251 B
and 4500-CIO₂ E in the 19th edition of Standard Methods
(APHA, 1995) were approved for HAA5 and daily chlorite analyses,
respectively. Three TOC methods (5310 B, 5310 C, and 5310 D) from the
Supplement to the 19th edition of Standard Methods (APHA, 1996) and one
UV₂₅₄ method (5910 B) from the 19th edition of Standard
Methods (APHA, 1995) were also approved in the Stage 1 DBPR.
These thirteen methods are unchanged in the 20th edition of
Standard Methods (APHA, 1998), so EPA proposes to cite the 20th edition
for these analyses in addition to the 19th editions.
The On-Line Version of Standard Methods is an effort to provide the
consensus methods to the public prior to the release of the next full
publication. Standard Methods is making sections of the next version
available for purchase in both electronic or printed format. EPA has
reviewed the applicable sections and determined that ten of the methods
are identical to the currently approved versions from the 19th
editions. Section 4500-Cl contains the methods for determining chlorine
residuals and it includes the 4500-Cl D, 4500-Cl F, 4500-Cl G, 4500-Cl
E, 4500-Cl I, and 4500-Cl H. Section 4500-ClO₂ contains the
methods for determining chlorine dioxide residuals and chlorite and it
includes method 4500-ClO₂ E. Section 5310 contains the
methods for determining TOC and it includes methods 5310 B, 5310 C, and
5310 D. Because the ten listed methods in these sections are unchanged
from the versions that were published in the 19th editions, EPA is
proposing to cite the On-Line Version for these analyses in

[[Page 49617]]

addition to the currently approved 19th editions and the proposed 20th
edition.
Section 6251 includes method 6251 B for HAA5. The method has been
updated for the On-Line Version to include precision and accuracy data
from the Information Collection Rule and the sample holding time has
been extended from 9 days to 14 days. The additional quality control
data does not technically change the method from the previously
approved version in the 19th edition; it simply demonstrates the
performance that can be expected when the method is used. The change in
sample holding time is consistent with EPA's proposal to standardize
the HAA5 sample holding time at 14 days (See discussion in section
V.O.7). Thus EPA is proposing to cite the On-Line Version for this
analysis in addition to the currently approved 19th edition and the
proposed 20th edition.
Section 5910 includes method 5910 B for determining
UV₂₅₄. The method has been updated for the On-Line Version
to include precision data from the Information Collection Rule. Because
the additional quality control data does not technically change the
method from the previously approved version in the 19th edition, EPA is
proposing to cite the On-Line Version for this analysis in addition to
the currently approved 19th edition and the proposed 20th edition.
The On-Line Version of Standard Methods will not include method
4500-ClO₂ D, so it is not being proposed with the other
twelve methods cited in the On-Line Version.
EPA is proposing to add a citation to the 20th edition and the On-
Line Version of Standard Methods for thirteen and twelve methods,
respectively. EPA believes these should be cited in addition to the
19th editions in order to allow flexibility for the water systems
performing the analyses. Withdrawal of the older editions would require
all systems to purchase one of the newer editions, which could impose
an unnecessary burden on systems that use the reference for only a few
methods.
6. What Is the Updated Citation for EPA Method 300.1?
EPA Method 300.1 (USEPA 2000l) for bromate, chlorite and bromide is
now included in an EPA methods manual that was published August 2000.
The manual titled ``Methods for the Determination of Organic and
Inorganic Compounds in Drinking Water'' is a compilation of methods
developed by EPA for drinking water analyses. EPA Method 300.1 was
previously only available as an individual method. EPA proposes to
update the bromate, chlorite, and bromide citation for this method to
the August 2000 methods manual in today's rule so that the users are
directed to the correct source of the method.
7. How Is the HAA5 Sample Holding Time Being Standardized?
The analytical methods approved for HAA5 compliance monitoring (EPA
552.1, EPA 552.2, and Standard Method 6251 B) all specify the use of
ammonium chloride to eliminate the free chlorine residual in samples
and they require samples be iced/refrigerated after collection. Even
though the sampling parameters agree in the three methods, the methods
specify different sample holding times (time between sample collection
and extraction). EPA Methods 552.1 (USEPA 1992) and 552.2 (USEPA 1995)
allow at least 14 days while Standard Method 6251 B (APHA 1995 and
1998) specifies that samples must be extracted within nine days of
sample collection. The holding time for the Standard Method is based on
data which indicated an increase in DCAA concentration to slightly
greater than 120% of the initial concentration after the sample was
stored for 14 days (Krasner et al. 1989). All other HAA5 compounds were
well within the 80-120% criteria set by the researchers. The decision
was made to use a conservative approach to be sure that the
concentrations of all HAAs were stable, and nine days was the closest
data point to the 14 day-data point in question. Subsequent to
Krasner's study, EPA conducted additional sample holding time studies
as part of the EPA methods development process. EPA has published data
to support the 14-day sample holding time for the HAA5 compounds
(Pawlecki-Vonderheide et al. 1997; USEPA 2003p). Since there is no
technical reason for the holding times to be different between the HAA5
methods addressed in this rule, EPA proposes to allow a 14-day sample
holding time for samples being analyzed by Standard Method 6251 B. This
would provide consistency across methods and it would simplify sampling
considerations for water systems. EPA is only proposing to standardize
the holding time allowed for the samples. Due to differences in the
sample preparation (i.e., extraction) procedures in the various
methods, the extract holding times cannot be standardized. Laboratories
must follow the individual method requirements when determining storage
conditions and holding times for the extracts.
EPA Method 552.1 specifies a 28-day holding time for HAA samples.
This was based on studies conducted on fortified reagent water samples
rather than drinking water samples. Because HAAs have been shown to
biodegrade in some distribution systems (Williams et al. 1995), EPA
believes that some samples may not be stable for 28 days. Today's rule
proposes reducing the holding time to 14 days when EPA Method 552.1 is
used in order to better ensure sample stability. During the Information
Collection Rule, EPA only allowed the 14-day sample holding time for
all HAA samples (regardless of the method used to analyze the samples),
so laboratories and water systems have demonstrated their capability to
implement this method change.
EPA believes that by standardizing the sample holding times allowed
in the various HAA5 methods, the burden for laboratories and water
systems will be reduced. Sampling considerations will be simplified,
because all HAA5 samples will be collected and stored the same way.
8. How Is EPA Clarifying Which Methods Are Approved for Magnesium
Determinations?
The Stage 1 DBPR allows systems practicing enhanced softening that
cannot achieve the specified level of TOC removal, to meet instead one
of several alternative performance criteria, including the removal of
10 mg/L magnesium hardness (as CaCO3) from the source water. Analytical
methods for measuring magnesium hardness were not included in the rule,
but they were later promulgated in a Methods Update Rule (USEPA 1999b).
The December 1999 Methods Rule cited the magnesium methods at Sec.
141.23(k)(1), but it did not identify that these methods were to be
used to demonstrate compliance with the alternative performance
criteria specified in Sec. 141.135(a)(3)(ii). EPA is proposing to
clarify this today by referencing the approved magnesium methods at
Sec. 141.131(d)(6) and Sec. 141.135(a)(3)(ii).
9. Which Methods Can Be Used To Demonstrate Eligibility for Reduced
Bromate Monitoring?
Today's rule proposes to change the monitoring requirements for
demonstrating eligibility to reduce bromate monitoring from monthly to
quarterly. The Stage 1 DBPR allows the monitoring to be reduced if the
system demonstrates that the average source water bromide concentration
is less than 0.05 mg/L based upon monthly bromide measurements for one
year. Today's rule proposes to change that requirement to a
demonstration that the finished water

[[Page 49618]]

bromate concentration is <0.0025 mg/L as a running annual average. If
this change is implemented, there will no longer be a need for bromide
compliance monitoring methods. EPA is proposing additional bromide
methods today in order to provide flexibility to the laboratories and
water systems in the interim period before the Stage 2 DBPR compliance
monitoring requirements becomes effective.
In order to qualify for reduced bromate monitoring, EPA is
proposing that the samples must be analyzed for bromate using either
EPA Method 317.0 Revision 2.0 (UV/Vis detector), EPA Method 326.0 (UV/
Vis detector), or EPA Method 321.8. These three methods can provide
quantitative data for bromate concentrations as low as 0.001 mg/L, thus
ensuring that a bromate running annual average of <0.0025 mg/L can be
reliably demonstrated. Laboratories that analyze samples by these three
methods must report quantitative data for bromate concentrations as low
as 0.001 mg/L.
Since EPA Methods 317.0 Revision 2.0, 326.0, and 321.8 offer
significantly greater sensitivity for bromate analyses, EPA considered
whether these should be the only methods approved for bromate
compliance monitoring. However, the new methods using postcolumn
reactions with UV/Vis detection (EPA Methods 317.0 Revision 2.0 and
326.0) or IC/ICP-MS (EPA Method 321.8) require greater analyst skill
than is necessary for the standard ion chromatographic (IC) methodology
(EPA Method 300.1 and ASTM Method D 6581-00). They also require
instrumentation that may not be currently owned by many laboratories
that perform bromate analyses. As a result of these factors and because
the standard IC methods are adequate for determining compliance with
the bromate MCL that was promulgated as part of the Stage 1 DBPR, EPA
decided not to propose withdrawal of the currently approved method (EPA
Method 300.1). In addition, EPA decided to propose ASTM Method D 6581-
00, because it is equivalent to EPA Method 300.1. EPA strongly
encourages laboratories to expand their services by adding the
capability to perform analyses using one of the more sensitive methods
for bromate. EPA believes that there will be a shift to the more
sensitive methods as water systems realize that the analytical
capabilities are available for a slightly increased analytical cost.
(The ability to determine bromate concentrations as low as 1 [mu]g/L
will provide water systems more information concerning the optimization
of ozone application to control for bromate formation.)
10. Request for Comments
EPA requests comments on whether the methods proposed today should
be approved for compliance monitoring.
EPA solicits comments as to whether standardizing the sample
holding times for the HAA5 methods is appropriate. Specifically, should
the sample holding time for Standard Method 6251 B be extended from 9
days to 14 days and should the sample holding time for EPA Method 552.1
be shortened from 28 days to 14 days?
EPA requests comments as to whether laboratories should be required
to switch to one of the more sensitive bromate methods for compliance
monitoring sample analyses. Should EPA Method 300.1 be withdrawn as a
compliance monitoring method for bromate and be replaced by EPA Methods
317.0 Revision 2.0, 326.0, and 321.8 which provide reliable data for
bromate concentrations as low as 1[mu]g/L?

P. Laboratory Certification and Approval

1. What Is EPA Proposing Today?
EPA recognizes that the effectiveness of today's proposed
regulation depends on the ability of laboratories to reliably analyze
the regulated disinfection byproducts at the proposed MCLs. EPA has
established a drinking water laboratory certification program that
States must adopt as part of primacy. Laboratories must be certified in
order to analyze samples for compliance with the MCLs. EPA has also
specified laboratory requirements for analyses, such as alkalinity,
bromide, disinfectant residuals, magnesium, TOC, and SUVA, that must be
conducted by parties approved by EPA or the State. EPA's ``Manual for
the Certification of Laboratories Analyzing Drinking Water'' (USEPA
1997b) specifies the criteria that EPA uses to implement the drinking
water laboratory certification program. Today's proposed rule maintains
the requirements of laboratory certification for laboratories
performing analyses to demonstrate compliance with MCLs and all other
analyses to be conducted by approved parties. It revises the acceptance
criteria for performance evaluation (PE) studies and proposes reporting
limits for the DBPs as part of the certification program. Today's rule
also proposes that TTHM and HAA5 analyses that are performed for the
IDSE or system-specific study be conducted by laboratories certified
for those analyses.
2. What Changes Are Proposed for the PE Acceptance Criteria?
The Stage 1 DBPR specified that in order to be certified the
laboratory must pass an annual performance evaluation (PE) sample
approved by EPA or the State using each method for which the laboratory
wishes to maintain certification. The acceptance criteria for the DBP
PE samples were set as statistical limits based on the performance of
the laboratories in each study. This was done because EPA did not have
enough data to specify fixed acceptance limits.
Subsequent to the 1998 promulgation, EPA evaluated the results for
the EPA Water Supply (WS) PE studies and the Information Collection
Rule PE studies to determine if fixed acceptance limits could now be
applied. (Fixed limits were used during the Information Collection
Rule).
Four different fixed limits (+/-20%, +/-30%, +/-40%, and +/-50% of
the true value) were applied to each analyte in the WS PE study TTHM,
HAA5, bromate, and chlorite samples. Successful analysis of the sample
was defined as passing all four THMs individually in the TTHM PE
sample; passing four of the five HAAs in the HAA5 PE sample; and
passing bromate and chlorite individually. The number and percentage of
laboratories that successfully passed each study sample were determined
for the four fixed limits. These results were then evaluated to
determine how narrow the criteria could be set in order to achieve
accurate data and also provide enough certified laboratories to meet
the capacity needs. Only the last six WS PE Studies administered by EPA
(WS36-WS41 conducted between 1996-1998) were used in the final
recommendation, because they provided a better estimate of current
laboratory capabilities. Table V-19 summarizes the results of this WS
PE Study evaluation.
The number of laboratories that analyzed WS TTHM PE samples was
significantly larger than for the other DBPs, because a laboratory
certification program for TTHM has been in effect since the
promulgation of the THM rule in 1979 (USEPA 1979). Most of the
analytical methods for TTHM have been in use for many years, and the
laboratories are experienced in their use. The Stage 1 DBPR established
the first requirements to monitor for the other DBPs and certification
was not required until December 2001. Therefore, the WS PE results for
HAA5, chlorite, and bromate were from laboratories that were not part
of a certification process and the laboratories

[[Page 49619]]

were using methods that were relatively new. In addition, the method
used for bromate during the WS studies was EPA Method 300.0 which was
replaced by EPA Method 300.1 in the Stage 1 DBPR, because Method 300.1
is more sensitive. Laboratories would be expected to have greater
success in passing the bromate PE samples using Method 300.1 and the
bromate methods that are being proposed in today's rule.

Table V-19.--Fixed Limit Evaluation of WS PE Studies 36--41
[Average # and % of labs successfully completing studies]
--------------------------------------------------------------------------------------------------------------------------------------------------------
+/-20% of TV +/-30% of TV +/-40% of TV +/-50% of TV
DBP Sample -------------------------------------------------------------------------------------------------------
#Labs %Labs #Labs %Labs #Labs %Labs #Labs %Labs
--------------------------------------------------------------------------------------------------------------------------------------------------------
TTHM............................................ 609 73 731 88 773 93 788 94
HAA5 \1\........................................ 50 37 83 61 103 75 115 84
chlorite........................................ 55 63 68 78 72 82 74 85
bromate......................................... 45 50 52 57 57 64 60 68
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Study 38 was excluded from this analysis, because a valid DCAA true value was not available for the HAA sample.

Based on the results from the analyses described previously, EPA
believes it is reasonable to set the TTHM acceptance criteria at +/-20%
around the study true values. The number of laboratories capable of
performing TTHM analyses is large and the results described previously
show that in the time frame of 1996-1998, over 70% of the laboratories
could successfully meet the +/-20% criteria. The PE studies conducted
during the Information Collection Rule used the same acceptance
criteria (USEPA 1996b).
The data indicate that +/-40% are probably the tightest criteria
that could be used to evaluate HAA5 PE samples. Setting this criteria
balances the need for approval of enough labs to meet monitoring
capacity and the need to provide data of acceptable accuracy. The +/-
40% criteria is consistent with the Information Collection Rule PE
study acceptance criteria and it is tighter than the criteria
established in the Stage 1 DBPR. During the Information Collection
Rule, laboratories that were approved using the +/-40% criteria were
able to provide accurate and precise data as evidenced by the quality
control data collected when the Information Collection Rule samples
were analyzed (Fair et al. 2002). Of the 1,250 Information Collection
Rule samples that were fortified with known amounts of HAAs, the median
recovery was 103% and the recoveries ranged between 89% and 120% in 80%
of the fortified samples. There were 1,211 Information Collection Rule
samples that were analyzed in duplicate and the median relative percent
difference for those HAA5 analyses was 4%. Ninety percent of the
analyses had RPDs less than 21%. EPA believes laboratories that are
certified using the +/-40% criteria in PE studies should be capable of
performing at a level comparable to the Information Collection Rule
laboratories.
EPA believes chlorite PE samples should be evaluated using a +/-30%
criteria. Over 70% of the laboratories could meet this requirement for
chlorite in the WS studies.
The percentage of passing labs for bromate is almost 60% when a +/-
30% criteria is applied to the WS study data. Since the data do not
accurately reflect the bromate methods that are now being used by
laboratories, EPA believes a greater percentage of laboratories would
pass the bromate PE study using today's technology. Unfortunately, EPA
does not have the data to verify this assumption, because EPA no longer
conducts PE studies. Even if the assumption is flawed, a 57% acceptance
rate would still provide enough certified laboratories to handle the
number of bromate samples required for compliance monitoring under the
Stage 1 DBPR.
The proposed acceptance criteria are listed in Table V-20.

Table V-20.--Proposed Performance Evaluation (PE) Acceptance Criteria
----------------------------------------------------------------------------------------------------------------
Acceptance
DBP limits Comments
(percent)
----------------------------------------------------------------------------------------------------------------
TTHM
Chloroform +/-20 Laboratory must meet all 4 individual THM
Bromodichloromethane +/-20 acceptance limits in order to successfully pass
Dibromochloromethane +/-20 a PE sample for THMs.
Bromoform +/-20
HAA5
Monochloroacetic Acid +/-40 Laboratory must meet the acceptance limits for 4
Dichloroacetic Acid +/-40 out of 5 of the HAA5 compounds in order to
Trichloroacetic Acid +/-40 successfully pass a PE sample for HAA5.
Monobromoacetic Acid +/-40
Dibromoacetic Acid +/-40
Chlorite +/-30
Bromate +/-30
----------------------------------------------------------------------------------------------------------------

EPA is also proposing that the PE acceptance limits described
previously become effective within 60 days of promulgation of the final
rule. This will allow the laboratory certification program to implement
the fixed limits as soon as possible. Laboratories that were certified
under the Stage 1 PE acceptance criteria would be subject to the new
criteria when it is time for them to analyze their annual DBP PE
samples(s).

[[Page 49620]]

3. What minimum reporting limits are being proposed?
The Consumer Confidence Reports Rule (USEPA 1998i) requires that
all detected regulated contaminants be reported in the annual reports,
but detection is not defined for the DBP contaminants. This rule
addresses the deficiency by proposing reporting limits for the
regulated DBPs.
Laboratories that analyze compliance samples must be able to
reliably measure the DBPs at concentrations below the MCL. Laboratories
must also be able to measure the individual TTHM and HAA5 compounds at
levels that are much lower than the MCLs for these compound classes,
because the MCLs are based on the sum of the individual compound
concentrations.
Historically, EPA has used practical quantitation levels to
estimate the lowest concentration at which laboratories can be expected
to provide data within specified limits of precision and accuracy
during routine operating conditions (USEPA 1985). The estimates are
based on PE data, if available, or are set at five or ten times the
method detection level.
In today's rule, EPA is proposing an alternate approach for
establishing the lowest concentration for which laboratories are
expected to report quantitative data for DBPs. The approach is based on
a unique data set from the Information Collection Rule. Laboratories
were required to meet specific quality control criteria when they
analyzed samples for the Information Collection Rule. The rule
established a regulatory minimum reporting level (MRL) for each analyte
and laboratories were required to demonstrate they could accurately
measure at these concentrations each time a set of samples was
analyzed. The regulatory MRLs were based on recommendations from
experts who were experienced in DBP analyses and were set at
concentrations for which most laboratories were expected to be able to
meet the precision and accuracy criteria under normal operating
conditions. Most samples were also expected to contain concentrations
greater than the specified MRLs.
EPA evaluated the data from the Information Collection Rule to
determine if the laboratories were able to reliably measure down to the
required MRL concentrations. Precision and accuracy data from the
calibration check standards prepared at the MRL concentrations (listed
in Table V-21) were examined. The data indicated most laboratories were
able to provide quantitative data for samples with these
concentrations.
Because laboratories demonstrated the capability to meet the
Information Collection Rule MRLs, EPA believes it is reasonable to
expect similar performance during the analyses of DBP compliance
monitoring samples. In today's rule, EPA is proposing to incorporate
MRL requirements into the laboratory certification program for DBPs and
to use regulatory MRLs as the minimum concentrations that must be
reported as part of the Consumer Confidence Reports (Sec. 141.151(d)).

Table V-21.--Proposed Minimum Reporting Level (MRL) Requirements
----------------------------------------------------------------------------------------------------------------
MRL ([mu]g/L)
----------------------------------
DBP Information Comments
collection Proposed stage
rule 2 DBPR
----------------------------------------------------------------------------------------------------------------
TTHM
Chloroform............................ 1.0 1.0
Bromodichloromethane.................. 1.0 1.0
Dibromochloromethane.................. 1.0 1.0
Bromoform............................. 1.0 1.0
HAA5
Monochloroacetic Acid................. 2.0 2.0
Dichloroacetic Acid................... 1.0 1.0
Trichloroacetic Acid.................. 1.0 1.0
Monobromoacetic Acid.................. 1.0 1.0
Dibromoacetic Acid.................... 1.0 1.0
Chlorite.................................. 20.0 200.0
Bromate................................... 5.0 5.0 or 1.0 Laboratories that use EPA Methods
317.0 Revision 2.0, 326.0, or
321.8 must meet a 1.0 [mu]g/L MRL
for bromate.
----------------------------------------------------------------------------------------------------------------

As part of the request for certification, EPA is proposing to
require laboratories to demonstrate they can reliably measure
concentrations at least as low as the ones listed in Table V-21 in
order to be certified for those parameters. This would mean that the
calibration curve must encompass the proposed regulatory MRL
concentration and that the laboratory must verify the accuracy of the
calibration curve at the lowest concentration for which quantitative
data are reported by analyzing a calibration check standard at that
concentration prior to analyzing each batch of samples. (Laboratories
would analyze a check standard at the specified MRL concentration daily
or each time samples are analyzed.) The measured concentration for this
check standard must be within +/-50% of the expected value.
Laboratories may choose to report quantitative data at concentrations
lower than the proposed regulatory MRLs as long as the required
accuracy criteria (+/-50% of the expected value) is met by daily
analyzing standards at the lowest reporting limit chosen by the
laboratory.
Laboratories were not given the opportunity to report
concentrations lower than the specified MRLs during the Information
Collection Rule. Some laboratories indicated they have met the
precision and accuracy criteria at lower concentrations, so EPA
believes that each laboratory should have the flexibility to continue
using its own reporting limits as long as the laboratory MRLs are not
higher than the regulatory ones proposed in this rule. This flexibility
would minimize the cost of implementing the regulatory MRL
requirements, because the laboratory would not have to make changes in
its established quality control procedures unless its procedures are
less stringent than those being proposed today. Requiring a laboratory
to adopt regulatory MRLs that are higher than the laboratory reporting
limits currently in

[[Page 49621]]

use offers no advantage and could increase analytical costs. The
capability to provide quantitative data at the laboratory's MRL or the
regulatory MRL would need to be demonstrated on a daily basis by
analyzing a check standard at that concentration and by achieving a
recovery in the range of 50 to 150%.
The proposed regulatory MRL for MCAA is 2.0 [mu]g/L based on the
Information Collection Rule performance data. However, MCAA was not
present at concentrations higher than this in more than half of the
samples analyzed for HAAs during the Information Collection Rule (USEPA
2003o). Some laboratories reported that they could have provided
quantitative data for MCAA down to concentrations as low as 1.0 [mu]g/
L.
EPA is proposing a regulatory MRL for chlorite that is much higher
than can easily be achieved using the approved or proposed methods. The
MRL specified during the Information Collection Rule was 20. [mu]g/L
and laboratories were able to successfully obtain quantitative data at
that level. However, in the context of this rule, EPA believes that
requiring laboratories to verify their calibration curves down to 20.
[mu]g/L each time samples are analyzed is unnecessary. This is because
chlorite analyses are only performed on samples from water plants that
use chlorine dioxide and most of the applied chlorine dioxide is
converted to chlorite, so the concentrations that are expected in most
compliance monitoring samples will be much higher than 20. [mu]g/L.
(The Information Collection Rule data showed a median chlorite
concentration of 380 [mu]g/L in the finished water and 333 [mu]g/L as
the distribution system average in systems using chlorine dioxide
(USEPA 2003o).) EPA is proposing a regulatory MRL of 200. [mu]g/L for
chlorite, because most of the samples are expected to contain
concentrations higher than 200. [mu]g/L. The MCL for chlorite is 1.0
mg/L (1,000 [mu]g/L). EPA recognizes that setting the regulatory MRL
for chlorite based on the concentrations expected to be found in the
samples rather than the sensitivity of the analytical method is
inconsistent with the approach taken for other compounds in this rule.
Nevertheless, EPA believes setting the MRL based on occurrence
information is appropriate because it will not compromise the
compliance data. Water systems would have the option of requiring that
laboratories establish a lower reporting limit when their samples are
analyzed and EPA would encourage this in cases in which the samples
consistently contain chlorite concentrations that are <200. [mu]g/L. If
a lower reporting limit is used, then the laboratory will be required
to meet the precision and accuracy requirements at that lower
concentration by daily successfully analyzing a check standard at the
laboratory reporting limit concentration prior to analyzing compliance
samples. EPA believes very few water systems will request more
sensitive chlorite analyses, because their samples won't have low
enough concentrations to require it.
EPA is proposing two regulatory MRLs for bromate analyses in
today's rule. This is because the traditional ion chromatographic (IC)
methods using conductivity detection (EPA Method 300.1 and ASTM Method
6581-00) are only capable of quantitating down to 5.0 [mu]g/L while the
new IC methods using either post column reactions with UV/Vis detection
(EPA Methods 317.0 Revision 2.0 and 326.0) or IC followed by ICP-MS
detection (EPA Method 321.8) can reliably quantitate bromate
concentrations as low as 1.0 [mu]g/L. EPA believes it is appropriate to
set the regulatory MRL based on the capability of the method. (EPA has
published detection limits for inorganic contaminants based on method
capability (Sec. 141.23(a)(4)(i)), so the approach proposed today is
consistent with previous regulations.) If the regulatory MRL is based
on the most sensitive method, then the routine IC methods could no
longer be used even though they are adequate for demonstrating
compliance with the bromate MCL. If the regulatory MRL is set using the
least sensitive method, then the feasibility for reduced bromate
monitoring based on a running annual average of <0.0025 [mu]g/L (<2.5
[mu]g/L) would not be adequately demonstrated based on data reported
with a reporting limit of 5.0 [mu]g/L.
EPA is proposing MRLs as part of the certification process.
Laboratories would be required to demonstrate they can reliably
quantitate at the specified MRL concentration when their current DBP
certification is subject to renewal or if they are applying for
certification for DBP methods for the first time. (Demonstration would
be accomplished by providing precision and accuracy data from the
analyses of check standards at or below the regulatory MRL
concentration over a several day period. The laboratory's standard
operating procedure for HAA5 analyses would include a requirement to
daily meet the MRL accuracy criteria for a check standard at or below
the regulatory MRL concentration.) Although ensuring laboratories can
meet the regulatory MRLs is a new certification requirement, EPA does
not believe this significantly increases the time required to review a
laboratory prior to certification. Each DBP method requires the
laboratory to generate a similar set of data at a higher concentration
and to meet specific accuracy and precision criteria as part of the
initial demonstration of laboratory capability to perform the method;
review of the MRL data set will be comparable to what is already being
done. This new requirement will ensure that laboratories can reliably
analyze samples that contain low concentrations of DBPs on an on-going
basis.
EPA is also proposing to require the regulatory MRLs be used for
compliance reporting by the Public Water Systems. Finally, the
regulatory MRLs would be used when Public Water Systems inform
customers of their water quality relative to DBP concentrations in the
annual Consumer Confidence Reports.
4. What Are the Requirements for Analyzing IDSE Samples?
EPA is proposing that the TTHM and HAA5 samples collected for the
Initial Distribution System Evaluations (IDSE) and the system specific
studies conducted in lieu of IDSEs be analyzed by certified
laboratories. EPA recognizes that this will require additional
laboratory capacity during the time period in which these studies are
conducted. The largest challenge will be in developing the capacity to
analyze the samples for the water systems that must complete the
studies, analyze the data, and recommend Stage 2 DBP sampling sites
within two years of the promulgation date of the rule. However, EPA
believes commercial laboratories, in particular, will be able to expand
their capacity to meet the demand based in the information presented
below.
Assuming no waivers or system-specific studies, the number of IDSE
samples is estimated to be between 14,000 and 21,000 per month in the
first round of IDSE monitoring, depending on whether the monitoring
requirements are based on population or number of treatment plants,
respectively. Laboratories should easily be able to accommodate this
increase in TTHM samples, because experience performing TTHM analyses
is spread across a large number of laboratories. Hundreds of
laboratories have been certified for TTHM analyses, since certification
was first required in 1979. There were close to 600 laboratories
certified to perform TTHM analyses in 1991. In the 1996-1998 period,
there were over 800 laboratories participating in the PE studies for
TTHMs and 600 of those laboratories were capable of meeting the

[[Page 49622]]

TTHM PE acceptance criteria proposed in today's rule. Many water system
laboratories are certified to perform TTHM analyses and will be able to
incorporate the IDSE TTHM samples from their systems into the
laboratory schedule. It is reasonable to expect that commercial
laboratories will be able to handle the remainder of the TTHM samples.
(EPA does not have a current estimate of the number of laboratories
certified to perform TTHM analyses. However, if the number of IDSE
samples from large systems was evenly spread over the 600 laboratories
that were certified in 1991, this would be less than 40 additional
samples per month for each laboratory. Analysis of 40 TTHM samples
would involve less than two days of analyst and instrument time which
does not seem unreasonable for commercial laboratories to accommodate.)
Analyses of the HAA5 samples will present a greater challenge,
because certification is relatively new for this measurement. EPA
anticipates that most of the HAA5 samples will be analyzed by
commercial and State laboratories, because the methods are more complex
than the TTHM analyses and monitoring was not widely required until
January 2002. Laboratories were not required to be certified to perform
HAA5 analyses until January 2002. However, the PE Study results from
1996-1998 indicate that over 130 laboratories were performing HAA5
analyses during that time frame and approximately 100 of those
laboratories were capable of meeting the HAA5 PE acceptance criteria
proposed in today's rule. Ninety-four laboratories were approved to
perform HAA analyses during the Information Collection Rule; twenty-
seven of them were commercial laboratories and nine were State
laboratories. EPA anticipates that large commercial laboratories
already certified to perform HAA5 analyses will recognize this market
potential and add staff and instrumentation to accommodate the
increased demand.
Most systems serving <10,000 people will not begin their IDSE
studies until after the large systems have completed their studies.
Even though the potential number of samples is greater, the small
systems have two additional years in which to complete their studies,
so there is more opportunity to schedule the sampling in such a manner
that laboratory capacity is maintained. The laboratory capacity should
be readily available by the time analyses of these samples are
required.
5. Request for Comments
EPA requests comments concerning the appropriateness of the
proposed PE acceptance criteria.
EPA solicits comments as to whether an MRL lower than 2 [mu]g/L is
feasible for MCAA and if so, what should that MRL concentration be?
EPA requests comments concerning whether the MRL for chlorite
should be based on the sensitivity of the method (i.e., 20. [mu]g/L) or
on the expected concentration range of the samples (i.e., 200. [mu]g/
L).
EPA solicits comments concerning which MRL approach should be
considered for bromate. Specifically, should EPA set the MRL based on
the capability of the method which would mean that two different MRLs
are defined or should one MRL be established based on either the least
or most sensitive method?
EPA requests comments concerning the appropriateness of the MRL
certification requirements and whether additional certification
requirements should be considered.
EPA solicits comments on the availability of laboratory capacity to
perform TTHM and HAA5 analyses for IDSE studies.

VI. State Implementation

This section describes the regulations and other procedures and
policies States would have to adopt to implement the Stage 2 DBPR, if
finalized as proposed today. States must continue to meet all other
conditions of primacy in 40 CFR part 142.
The SDWA establishes requirements that a State or eligible Indian
Tribe must meet to assume and maintain primary enforcement
responsibility (primacy) for its public water systems. These SDWA
requirements include: (1) adopting drinking water regulations that are
no less stringent than Federal drinking water regulations, (2) adopting
and implementing adequate procedures for enforcement, (3) keeping
records and making reports available on activities that EPA requires by
regulation, (4) issuing variances and exemptions (if allowed by the
State), under conditions no less stringent than allowed under the SDWA,
and (5) adopting and being capable of implementing an adequate plan for
the provision of safe drinking water under emergency situations.
General rule implementation activities include notifying systems of
rule requirements, updating internal and external databases, providing
training and technical assistance, and reviewing (and, if necessary,
approving) monitoring and other reports and plans.
To receive primacy for the Stage 2 DBPR, when final, States will be
required to adopt the following new or revised requirements under their
own regulations:

--Section 141.33(a) and (f), Record maintenance;
--Section 141.64, MCLs for disinfection byproducts;
--Subpart L, Disinfectant Residuals, Disinfection Byproducts, and
Disinfection Byproduct Precursors;
--Subpart O, Consumer Confidence Reports;
--Subpart Q, Public Notification of Drinking Water Violations;
--Subpart U, Initial Distribution System Evaluation; and
--Subpart V, Stage 2B Disinfection Byproducts Requirements.

In addition to adopting basic primacy requirements specified in 40
CFR part 142, States are required to address applicable special primacy
conditions. Special primacy conditions pertain to specific regulations
where implementation of the rule involves activities beyond general
primacy provisions. The purpose of these special primacy requirements
in today's proposal is to ensure State flexibility in implementing a
regulation that: (1) Applies to specific system configurations within
the particular State and (2) can be integrated with a State's existing
Public Water Supply Supervision Program. States must include these
rule-distinct provisions in an application for approval or revision of
their program. These primacy requirements for implementation
flexibility are discussed in the following section.

A. State Primacy Requirements for Implementation Flexibility

To ensure that a State program includes all the elements necessary
for an effective and enforceable program within that State under
today's rule, a State primacy application must include a description of
how the State will review IDSE reports and approve new or revised
monitoring sites for long-term DBP compliance monitoring. If a State
will use the authority to grant blanket waivers for IDSE requirements
to very small systems, it must comply with the special primacy
provision for granting such waivers. A State that intends to use the
authority for addressing consecutive system monitoring requirements
must include a description of how it intends to implement that
authority. A State primacy application must also include a description
of how the State will require systems to identify significant
excursions.

[[Page 49623]]

B. State Recordkeeping Requirements

The current regulations in Sec. 142.14 require States with primacy
to keep various records, including analytical results to determine
compliance with MCLs, MRDLs, and treatment technique requirements;
system inventories; State approvals; enforcement actions; and the
issuance of variances and exemptions. The proposed Stage 2 DBPR
requires that the State keep records related to any decisions made
pursuant to the requirements in subparts U and V, plus copies of IDSE
reports submitted by systems until those reports are reversed or
revised in their entirety. Today's proposal also includes a revision to
the State recordkeeping requirements that requires States to maintain
records of DBP monitoring plans submitted by public water systems until
superceded by a new system monitoring plan.

C. State Reporting Requirements

EPA currently requires in Sec. 142.15 that States report
information such as violations, variance and exemption status, and
enforcement actions to EPA. The proposed Stage 2 DBPR will not add any
additional reporting requirements.

D. Interim Primacy

On April 28, 1998, EPA amended its State primacy regulations at 40
CFR 142.12 to incorporate the new process identified in the 1996 SDWA
Amendments for granting primary enforcement authority to States while
their applications to modify their primacy programs are under review
(63 FR 23362) (USEPA 1998j). The new process grants interim primary
enforcement authority for a new or revised regulation during the period
in which EPA is making a determination with regard to primacy for that
new or revised regulation. This interim enforcement authority begins on
the date of the complete primacy application submission or the
effective date of the new or revised State regulation, whichever is
later, and ends when EPA makes a final determination. However, this
interim primacy authority is only available to a State that has primacy
for every existing NPDWR in effect when the new regulation is
promulgated.
As a result, States that have primacy for every existing NPDWR
already in effect may obtain interim primacy for this rule, beginning
on the date that the State submits the application for this rule to
EPA, or the effective date of its revised regulations, whichever is
later. In addition, a State which wishes to obtain interim primacy for
future NPDWRs must obtain primacy for this rule.

E. IDSE Implementation

As discussed in section V.J., many systems will be performing
certain IDSE activities prior to their State receiving primacy. During
that period, EPA will act as the primacy agency, but will consult and
coordinate with individual States to the extent practicable and to the
extent that States are willing and able to do so. In addition, prior to
primacy, States may be asked to assist EPA in identifying and
confirming systems that are required to comply with certain IDSE
activities. Once the State has received primacy, it will become
responsible for IDSE implementation activities.

F. State Burden

Section VII of today's document contains an analysis of the burden
that this rule will place on States in receiving primacy and
implementing this rule.

G. Request for Comment

EPA requests comment on the State implementation requirements
including the special primacy requirements.

VII. Economic Analysis

This section summarizes the Health Risk Reduction and Cost Analysis
(HRRCA) in support of the Stage 2 DBPR as required by section
1412(b)(3)(C) of the 1996 SDWA. In addition, under Executive Order
12866, Regulatory Planning and Review, EPA must estimate the costs and
benefits of the Stage 2 DBPR in an Economic Analysis (EA). EPA has
prepared an EA to comply with the requirements of this order and the
SDWA Health Risk Reduction and Cost Analysis (HRRCA) (USEPA 2003i).
SDWA (Section 1412 (b)(4)(C)) also requires the Agency to determine
that the benefits of the promulgated rule would justify the costs of
compliance. The proposed EA is available in the docket and is also
published on the Agency's web site: http://www.epa.gov/edocket.
It is important to note that the regulatory options considered by
the Agency are the direct result of an Advisory Committee process that
involved various drinking water stakeholders. More information on this
process is discussed in sections II and V of today's preamble.
In order to analyze both benefits and costs of the proposed rule
and other regulatory alternatives considered by the Agency, EPA relied
on several data sources to understand DBP occurrence, an analytical
model to predict treatment changes and changes in DBP occurrence, and
input and analysis from expert technical review panels to assist with
model validation and technology selection. A brief description of the
process is outlined in section VII.E. but a more detailed explanation
of the analytical process is in the EA for the proposed Stage 2 DBPR
(USEPA 2003i).
The Stage 2 DBPR economic impact analysis uses a model, (referred
to as the Surface Water Analytical Tool or SWAT) and information
collected under the Information Collection Rule to make predictions
about finished water and delivered water DBP levels, as well as
predicting technology changes necessary for systems to comply with rule
alternatives. Specifically, SWAT estimates post-Stage 1 DBPR (pre-Stage
2) and post-Stage 2 DBPR DBP levels and likely technology choices by
the industry to achieve compliance. For smaller systems and for all
ground water systems, expert panels considered occurrence data and
current treatment technology specific to these systems and used this
information to predict technology treatment changes that may result
from this proposed rule.
Both benefits and costs are presented as annualized values. The
process allows comparison of cost and benefit streams that are variable
over a given time period. The time frame used for both benefit and cost
comparisons is 25 years; approximately five years account for rule
implementation and 20 years for the average useful life of the
equipment. The Agency uses social discount rates of both three percent
and seven percent to calculate present values from the stream of
benefits and costs and also to annualize the present value estimates.
The EA for the proposed rule (USEPA 2003i) also shows the undiscounted
stream of both benefits and costs over the 25 year analysis period.

A. Regulatory Alternatives Considered by the Agency

Today's proposed Stage 2 DBPR represents the second of a set of
rules that address public health risks from DBPs. The Stage 1 DBPR was
promulgated to decrease average exposure to DBPs and associated health
risks by focusing compliance on MCLs based on average concentrations of
TTHM and HAA5 within the distribution system. Today's proposed Stage 2
DBPR further reduces exposure to chlorinated DBPs by basing compliance
on the LRAA of TTHM and HAA5 concentrations at each sampling point
within the distribution system. Section V illustrated the LRAA concept
and differences in the two compliance calculation methodologies. In
addition,

[[Page 49624]]

section V provided a comparison of the regulatory options considered.
This subsection will summarize the comparison of options and subsection
VII.B. will outline the exposure analyses that led EPA to propose the
preferred option and will present the predicted national occurrence
distributions that were used to quantify predicted exposure reductions
from today's proposed rule. A detailed discussion of EPA's exposure
analyses can be found in the Economic Analysis for the Stage 2 DBPR
(USEPA 2003i).
There are two components in the Agency's M-DBP regulatory
development process that are particularly relevant to evaluation of
options discussed in today's proposal: (1) the data synthesis and
evaluation resulting from the Information Collection Rule; and (2) the
analysis and recommendations of the M-DBP Advisory Committee. Data from
the Information Collection Rule were used with the SWAT model to
estimate the national distributions of DBP occurrence. The Advisory
Committee considered several questions during the negotiation process,
including:

--What are the remaining health risks after implementation of the Stage
1 DBPR?
--What are approaches to addressing these risks?
--What are the risk tradeoffs that need to be considered in evaluating
these approaches?
--How do the estimated costs of the approach compare to reductions in
peak occurrences and overall exposure for that approach? How does this
measure (ratio of costs to exposure reduction) compare among the
approaches?

The Advisory Committee considered the DBP occurrence estimates and
characteristics of these distributions to be important in understanding
the nature of public health risks. Although the Information Collection
Rule data were collected prior to promulgation of the Stage 1 DBPR, the
data support the concept that a system could be in compliance with the
Stage 1 DBPR MCLs of 0.080 mg/L and 0.060 mg/L for TTHM and HAA5,
respectively, and yet have points in the distribution system with
either periodically or consistently higher DBP levels (see section IV).
Based on these findings, and in order to address disproportionate
risk within distribution systems, the Advisory Committee discussed an
array of options that would base compliance on exposure at specific
sampling locations rather than on average exposures for the entire
distribution system. These included options for determining compliance
as an LRAA (requiring systems to meet the MCL at individual sampling
locations as a running annual average) or as absolute maximums
(requiring that no samples taken exceed the MCL concentration), in
addition to a combination of these approaches. For example, the
Advisory Committee reviewed the exposure reductions for a number of
approaches based on different LRAA and absolute maximum incremental MCL
levels, and combinations of an LRAA approach with a companion absolute
maximum for a variety of different concentration levels. The Advisory
Committee also evaluated the associated technology changes and costs
for these alternatives. In the process of narrowing down alternatives
based on this vast amount of information, the Advisory Committee
primarily focused on four types of alternative rule scenarios
illustrated next.
Preferred Alternative
--Long-term MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 as
LRAAs.
--Bromate MCL remaining at 0.010 mg/L.
Alternative 1
--Long-term MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 as
LRAAs.
--Bromate MCL of 0.005 mg/L.
Alternative 2
--Long-term MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 as
absolute maximums for individual measurements.
--Bromate MCL remaining at 0.010 mg/L.
Alternative 3
--Long-term MCLs of 0.040 mg/L for TTHM and 0.030 mg/L for HAA5 as an
RAA.
--Bromate MCL remaining at 0.010 mg/L.

Figure VII-1 shows how compliance would be determined under each of
the TTHM/HAA5 alternatives described and the Stage 1 DBPR for a
hypothetical large surface water system. This hypothetical system has
one treatment plant and measures TTHM in the distribution system in
four locations per quarter (the calculation methodology shown would be
the same for HAA5). Ultimately, the Advisory Committee recommended the
Preferred Alternative in combination with an IDSE requirement.
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The Preferred Alternative, coupled with the IDSE's refocused
sampling (see section V), was recommended by the Advisory Committee
because this approach addresses the objective of reducing potential
adverse reproductive and developmental health risks. It achieves this
objective by controlling peak TTHM and HAA5 concentrations at sites
throughout the distribution system without compromising microbial
protection. At the same time, it will only require a few higher risk
systems to face the cost of employing additional advanced technologies.
While this alternative controls the occurrence of consistently high DBP
levels, it is still possible that individual samples could exceed the
MCL, and consumers could thus be exposed to higher DBP concentrations
for some portion of the year. In addition, this alternative will
further reduce average DBP levels as systems make changes to reduce
these peak concentrations. Subsection VII.B. will show how today's
proposed requirements are predicted to decrease exposure risks. The
benefits and costs of each alternative are presented in subsections
VII.C. through VII.E.

[[Page 49626]]

B. Rationale for the Proposed Rule Option

DBP concentrations can be highly variable throughout a distribution
system and over time at the same location in a distribution system
(USEPA 2003o). The determination of compliance with an RAA under the
Stage 1 DBPR requires a system to average all of their spatially-
distributed samples collected in one quarter of the year and to combine
this average concentration with the three prior quarterly averages
determined by the system. Thus, the RAA-based standard allows utilities
to average spatial and temporal variability in TTHM and HAA5 samples to
determine compliance, as shown in figure VII-1. This allows lower
results found, perhaps, nearer a water treatment plant to offset higher
results that might be found at the ends of the distribution system. In
addition, systems with multiple plants of differing water quality
(either multiple surface water plants or surface and ground water
plants) may have particular plant distribution system sampling
locations with high DBPs that are offset by lower measurements observed
in the portion of the distribution network served by other plants.
Under the Stage 2 DBPR proposed today, TTHM and HAA5 MCLs will
remain the same, but compliance will be based on a locational running
annual average (LRAA) for each of the sampling sites in the
distribution system. In addition, the IDSE requirement will increase
the probability that the compliance sampling sites will capture the
highest DBP levels in the distribution system. Thus, the reduction in
DBP exposure from the Stage 1 DBPR to the proposed Stage 2 DBPR results
from the revised requirements for compliance calculations combined with
new compliance monitoring sites.
EPA expects the Stage 2 DBPR, as proposed, will result in health
benefits by reducing the estimated health risks associated with the
following exposures:

--Individual TTHM/HAA5 occurrences significantly exceeding 0.080 mg/L
and 0.060 mg/L;
--Chronic exposures at individual distribution system locations that
average more than 0.080 mg/L and 0.060 mg/L;
--Chronic exposures at all locations in the distribution system by
reducing overall system average DBP concentrations; and
--Chronic and peak exposures in consecutive systems (systems that
purchase treated water from another system).

Under the Stage 1 DBPR, high DBP concentrations at specific
locations in the distribution system could be masked by spatial and
temporal averaging. As discussed in subsection VII.C, short term
exposures resulting from these high concentrations may be of concern in
regard to potential adverse reproductive and developmental health
effects. Chronic exposures at locations having repeated high DBP
concentrations may be of concern for cancer endpoints as well. The
remainder of this subsection will illustrate how today's proposed rule
is expected to reduce ``peak'' and average exposures to address these
health concerns.
1. Reducing Peak Exposure
EPA used Information Collection Rule data to estimate the reduction
in exposure to DBP peaks resulting from the Stage 2 DBPR. Because the
Information Collection Rule data represent pre-Stage 1 DBPR conditions,
subsets of those plants already in compliance with the Stage 1 DBPR and
Stage 2 DBPR were used to estimate pre-Stage 2 and post-Stage 2
occurrence respectively. By comparing these subsets of data, EPA
estimated that approximately 69% of plant locations having TTHM peaks
greater than 0.080 mg/L remaining after the Stage 1 DBPR could be
reduced through implementation of the Stage 2 DBPR. EPA conducted this
additional peak reduction analysis only for TTHMs and not HAA5s because
current epidemiological data only considers the association between
TTHM exposure and adverse health impacts (see subsection VII.C).
Additional information on reduction of peak exposures can be found in
section 5.4.1 of the Economic Analysis (USEPA 2003i). EPA recognizes
that temporal and spatial variability in systems that need to install
treatment to comply with the Stage 1 DBPR may be different than in
those that do not, perhaps due to low source water TOC concentrations.
However, EPA does not have data representing DBP levels post-Stage 1.
EPA requests comment on its approach of using data from plants in
compliance with Stage 1 DBPR requirements without implementing
additional treatment as a proxy for post-Stage 1 DBP levels.
2. Reducing Average Exposure
To quantify the benefits of today's proposed rule, EPA compared
predicted post-Stage 2 DBPR occurrence and compared this to the
predicted baseline concentrations after the Stage 1 DBPR to determine
reductions in exposure resulting from the Stage 2 DBPR. The SWAT model
was the main tool used in this analysis. SWAT results were used
directly for medium and large surface water systems. For small surface
water systems and all ground water systems. Adjustments were made to
the SWAT results to account for different percentages of plants
changing technology to meet Stage 2 DBPR requirements. The Economic
Analysis for today's proposed rule (USEPA 2003i) provides an in-depth
discussion of this analysis.
Table VII-2 shows the reduction in average plant-level TTHM and
HAA5 concentrations estimated to result from the Stage 2 DBPR. EPA
expects average DBP levels to decline by 4.7 percent for all surface
water systems. DBP averages are expected to decline by 2.2 percent for
all large ground water systems and 1.7 percent for all small ground
water systems. These estimates include both systems already in
compliance with the Stage 2 DBPR and systems making treatment changes
to comply with the rule. The Agency uses these national average
reductions to quantify the primary benefit of this rule which is the
estimated range of reduction in bladder cancer cases nationally.
Systems making treatment changes to comply with the rule will
experience significantly greater estimated average reductions than the
national average for all systems. Chapter 5 of the EA (USEPA 2003i)
includes a more detailed discussion of this analysis.

Table VII-2.--Reduction in Average DBP Levels from Pre-Stage 2 to Post-Stage 2 (all plants)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Average plant-level TTHM Average plant-level HAA5
System size concentrations ([mu]g/L) concentrations ([mu]g/L)
Source water (population -----------------------------------------------------------------------------
served) Post-stage Percent Post-stage Percent
Pre-stage 2 2 reduction Pre-stage 2 2 reduction
--------------------------------------------------------------------------------------------------------------------------------------------------------
SW........................................................ <= 10,000 35.5 33.8 4.7 25.0 23.8 4.7

[[Page 49627]]

£ 35.5 33.8 4.7 25.0 23.8 4.7
10,000
-----------------------------------------------------------
GW........................................................ <= 10,000 16.0 15.6 2.2 8.5 8.3 2.2
10,000 16.2 16.0 1.7 8.6 8.5 1.7
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Due to rounding, percent reductions calculated from data in the tables may differ from the actual values presented here
Source: Economic Analysis (USEPA 2003i) Exhibit 5.22b

C. Benefits of the Proposed Stage 2 DBPR

As described previously, the Stage 2 DBPR is expected to reduce
both peak and long-term exposure to DBPs, thereby reducing the
potential risk of both adverse reproductive and developmental health
effects and bladder cancer. As discussed in section III of this
preamble, both epidemiological and toxicological evidence suggest a
possible increased risk for pregnant women and their fetuses who are
exposed to DBPs in drinking water. The Agency believes and the Advisory
Committee concluded that the weight of evidence is enough to take
regulatory action to help address the potential reproductive and
developmental endpoints in the Stage 2 DBPR. However, data are not
available at this time to conduct a traditional quantitative risk
assessment. Instead, the benefits from reducing most reproductive and
developmental risks are discussed qualitatively in this preamble. For
one endpoint, fetal loss, the Agency provides an illustrative
calculation to explore the implications of some published results for
potential benefits associated with reducing fetal losses that may be
attributable to certain DBP exposures.
In addition to achieving greater protection from possible adverse
reproductive and developmental health effects, the rule may provide
additional reduction in bladder cancer cases as the overall level of
DBPs in distribution systems nation-wide decreases. The Agency
estimated and monetized the potential benefits from reduction in
bladder cancers resulting from this rule. Reductions in bladder cancer
(including both fatal and non-fatal cases) provide a range of
annualized present value benefits from $0 to $986 million using a three
percent discount rate ($0 to $854 million using a seven percent
discount rate) depending on the risk level assumed. These estimates are
based on the assumption that the percent reductions in TTHM and HAAs
will correspond to the percent reductions in bladder cancer risk
attributed to populations receiving chlorinated drinking water as
indicated by various epidemiology studies (USEPA 1998a). Zero is
included in this range because of the inconsistent evidence regarding
the association between exposure from DBPs and cancer.
Other regulatory alternatives considered by the FACA committee and
the Agency could provide greater benefits but with greater technology
cost implications. Table VII-3 presents benefits estimates of the
proposed Stage 2 DBPR using two population attributable risks derived
from published studies (2% and 17%) and assuming there is a causal link
between DBP exposure and bladder cancer. In subsection VII.G., Table
VII-14 shows potential benefits of all regulatory alternatives
considered by the Agency.
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It is important to note that the monetized benefits only reflect
estimated benefits from reductions in bladder cancer. As shown in
subsection VII.C.1.and in Table VII-3, there may be significant
nonquantifiable benefits associated with regulating DBPs in drinking
water. Were EPA able to quantify some of the currently nonquantifiable
health effects and other benefits potentially associated with DBP
regulation, monetized benefits estimates could be significantly higher
than what is shown in the table. A complete discussion of how EPA
calculated the risks and the corresponding health benefits potentially
associated with exposure to DBPs in drinking water can be found in the
Stage 2 DBPR EA (USEPA 2003i).
For additional perspective EPA used updated cancer risk factors for
four DBPs for which we have toxicological data. Table III-3 (see
section III of this preamble) shows the estimated pre-Stage 2
concentrations of these four compounds and the estimated number

[[Page 49629]]

of people exposed to them. The Agency used these four DBPs to calculate
an alternative baseline number of annual pre-Stage 2 cancer cases. The
calculations use the linearized multistage model and predict 37 cases
for the ED₁₀ risk factors and 87 cases for the
LED₁₀ risk factors. The ED₁₀ risk factors (also
known as the maximum likelihood estimate) are based on the estimated
dose that the model predicts will result in a carcinogenic response in
10 percent of the subjects, while LED₁₀ risk factors
correspond to the lower 95% confidence bound on the dose that the model
predicts will result in a carcinogenic response in 10% of the subjects
(LED₁₀ is EPA's more conservative and more commonly used
expression of toxicologically based cancer risk). Assuming that DBP
risk reductions for Stage 2 for the entire population average 4.2%
(corresponding to the reduction in average TTHM levels), Stage 2 cancer
cases avoided based on the toxicological data range from 1.7 to 4.0
cases per year. Section 5.2.2.2 of the Economic Analysis (USEPA 2003i)
presents a more detailed basis for the derivation of these estimates.
It is important to note that these estimates do not include risks from
dermal or inhalation exposure nor do they account for many other DBPs
(or the mixture of DBPs seen in actual PWSs) for which occurrence or
toxicological risk data do not exist.
1. Non-Quantifiable Health and Non-Health Related Benefits
Although there are significant monetized benefits that may result
from this rule from the reduction in bladder cancer, other important
potential benefits of this rule are not quantified including potential
reductions in adverse reproductive and developmental effects and other
cancers.
The primary purpose of the Stage 2 DBPR is to address potential
adverse reproductive and developmental health effects that might be
associated with DBP exposure. EPA concludes that, ``the epidemiologic
data, although not conclusive, are suggestive of potential
developmental, reproductive, or carcinogenic health effects in humans
exposed to DBPs'' (Simmons et al 2002). EPA does not believe the
available evidence provides an adequate basis for quantifying potential
reproductive/developmental risks. Nevertheless, given the widespread
nature of exposure to DBPs and the priority our society places on
reproductive/developmental health, and the large number of fetal losses
experienced each year in the U.S. (nearly 1 million (Ventura et al.
2000)), we believe it is important to provide some quantitative
indication of the potential risk suggested by some of the published
results on reproductive/developmental endpoints, despite the absence of
certainty regarding a causal link between disinfection byproducts and
these risks. To do this, we have adapted illustrative PAR calculations
from several studies on the relationship between chlorinated water
exposure and fetal loss and applied these to national statistics on
annual incidence of fetal loss.
Specifically, we calculate the unadjusted population attributable
risk associated with each of the three distinct population-based
epidemiological studies of fetal loss published: Waller et al. 2001,
King et al. 2000a, and Savitz et al. 1995. All three are high quality
studies that have sufficient sample sizes and high response rates,
adjust for known confounders \2\, and have exposure assessment
information from water treatment data, residential histories, and THM
measurements. Because the populations in these three studies appear to
have TTHM exposures significantly greater than those of the general
U.S. population, we have chosen to scale the results using Information
Collection Rule data to allow us to derive population attributable
risks that may be more relevant to the general U.S. population (USEPA
2003i).
---------------------------------------------------------------------------

\2\ Use of unadjusted PAR estimates has the effect of removing
the adjustments for known confounders, however, EPA believes the
unadjusted estimates are adequate for purposes of the illustrative
calculations presented here.
---------------------------------------------------------------------------

These three studies (using unadjusted data to allow for
comparability, and scaled to the TTHM levels reported in the
Information Collection Rule data base) yield median PARs of 0.4%, 1.7%,
and 1.7% (with 95% confidence intervals for each of the studies of 0 to
4%) \3\. Using the prevalence of fetal loss reported by CDC, the median
PARs for these three studies suggest that the incidence of fetal loss
attributable to exposure to chlorinated drinking water could range from
3,900 to 16,700 annually. As part of the analysis to evaluate potential
reduction in fetal loss for the Stage 2 DBPR, EPA assumed that
reductions in risk are proportional to the 28 percent reductions in the
number of locations having one or more quarterly TTHM measurements that
exceed the study population cut-offs (£75 to £81
ug/l, depending on study). This analysis implies that a range of 1,100
to 4,700 fetal losses could be avoided per year as a result of the
Stage 2 rule.
---------------------------------------------------------------------------

\3\ The negative lower 95% confidence intervals for all three
studies was truncated at zero.
---------------------------------------------------------------------------

Caution is required in interpreting the numbers because many
experts recommend that population attributable risk analysis should not
be conducted unless causality has been established. Causality has not
been established between exposure to disinfection byproducts and fetal
loss. The estimates presented here are not part of EPA's quantitative
benefits analysis, and the ranges are not meant to suggest upper and
lower bounds. Rather, they are intended to illustrate quantitatively
the potential risk implications of some of the published results.
EPA has not monetized the value of potential reductions in fetal
loss, but recognizes that there is a significant value associated with
improvements in reproductive and developmental health. In the absence
of valuation studies specific to the health endpoints of concern, the
Agency typically draws upon existing studies of similar health
endpoints to estimate benefits. The ``transfer'' of the results of
these studies to value similar health endpoints must be done carefully
and methodically, controlling for differences in the health endpoints
and in the relevant populations. Some researchers have attempted to
transfer values using sophisticated analytical techniques such as
preference calibration methods (e.g., Smith et al. 2002). Regardless of
the approach used, ``benefit transfer'' requires systematic comparison
of the differences in the health effects in the studies and those
resulting from the regulation. Application of benefit transfer leads to
a detailed qualitative examination of the implications of using those
studies and potentially to empirical adjustments to the results of the
existing studies.
The Agency is investigating further work specific to the case of
fetal loss valuation. One possible area of further research is the
value that prospective parents attach to reducing risks during
pregnancy. In this regard, the substantial lifestyle changes that
prospective parents often undertake during pregnancy suggests that
reducing these kinds of risks is of value. A second possible area of
further investigation would be work on benefit transfer methodologies
that address how existing studies can inform the estimation of the
benefits of reduced fetal loss.
EPA has not monetized the potential reductions in fetal loss.
Without more information and discussion on these subjects the Agency
cannot fully consider and describe the implications of relying upon
existing studies.

[[Page 49630]]

However, research on valuation and benefit transfer continues to
progress and the Agency anticipates new research and future efforts to
value reproductive and developmental endpoints.
EPA was also unable to quantify or monetize the benefit from
potential reductions in other cancers, such as colon and rectal, that
may result from this rule. Both toxicology and epidemiology studies
indicate that other cancers may be associated with DBP exposure but
currently there is not enough data to quantify or monetize these cancer
risks.
Other potential non-health related benefits not quantified or
monetized in today's proposed rule include reduced uncertainty about
becoming ill from consumption of DBPs in drinking water, the ability
for some treatment technologies to eliminate or reduce multiple
contaminants, and monitoring changes that will ensure that systems can
effectively measure their DBP levels resulting in greater equity in
protection from DBPs. First, the reduced uncertainty concept depends on
several factors including consumer's degree of risk aversion, their
perceptions about drinking water quality (degree to which they will be
affected by the regulatory action), and the expected probability and
severity of human health effects associated with DBPs in drinking
water. This effect could be positive or negative depending on whether
knowledge of the rule decreases or increases their concern about DBPs
in drinking water and potentially associated health effects.
Another nonquantified potential benefit is the impact of technology
selection to address DBPs on a system's ability to address other
contaminants. For example, membrane technology (depending on pore
size), can be used to lower DBP formation but it can also remove other
contaminants that EPA is in the process of regulating or considering
regulating. Therefore, by installing membrane technology, a system may
not have to make new capital improvement to comply with future
regulations.
Last, today's proposed rule makes changes to Stage 1 monitoring
requirements. The IDSE monitoring provision of the proposed Stage 2
DBPR will help systems identify locations to conduct their routine
monitoring to capture high DBP occurrence levels. Also, the proposed
Stage 2 DBPR will prevent a system from conducting sampling designed to
avoid monitoring when DBP formation is generally higher. For example,
the Stage 1 DBPR required systems to take quarterly samples but samples
could conceivably be taken in December (4th quarter) and January (1st
quarter) when the waters in the distribution system are colder and DBP
formation generally lower. The proposed Stage 2 DBPR addresses this
issue by requiring that the samples must be taken about 90 days apart.
The benefits of these provisions include the greater certainty that
health protection is actually achieved because it is more likely that a
system's high DBP levels will be identified. In addition, the rule will
reduce variability in the DBP levels throughout the distribution
system, ensuring greater equity in public health protection.
2. Quantifiable Health Benefits
Although DBPs in drinking water have been associated with non-
cancerous health effects discussed previously, the quantified benefits
that result from today's rule are associated only with estimated
reductions in DBP-related bladder cancer. A complete discussion of risk
assessment methodology and assumptions can be found in Chapter 5 of the
Stage 2 DBPR Economic Analysis (USEPA 2003i). Section III of this
preamble also discusses the health effects that have been associated
with DBP exposure.
The annualized present value benefits for reductions in bladder
cancer that are the result of today's rule for both community water
system (CWS) and non-transient non-community water systems (NTNCWSs)
range from $0 to $986 million using a three percent discount rate ($0
to $854 million using a seven percent discount rate). Overall, the
Stage 2 DBPR may reduce on average 0 to 182 bladder cancer cases per
year.
The lower estimate of zero is included because of inconsistent
evidence regarding the association between exposure to DBPs and cancer.
The upper estimate of monetized benefits and cases avoided is based on
a population attributable risk (PAR) of 17 percent. Table VII-3 also
presents monetized benefits based on a PAR value of 2%. The PAR
estimates are derived from an analysis of five epidemiological studies
which indicate that perhaps 2 to 17 percent of bladder cancers may be
attributable to DBP exposure. These PAR estimates are described in more
detail in section III of today's document. These are the same PAR
values that EPA used in the Stage 1 DBPR benefits analysis, as
discussed in the Regulatory Impact Analysis for the Stage 1 DBPR (USEPA
1998f). Table VII-3 shows the estimated benefits associated with
bladder cancer reduction as a result of the proposed rule. Table VII-4
summarizes the mean, median and confidence intervals used to value
reductions in bladder cancer.
To calculate the total value of benefits derived from reductions in
bladder cancer cases as a result of the Stage 2 DBPR, a stream of
estimated monetary benefits is calculated by combining the annual cases
avoided with valuation inputs using Monte Carlo simulation. Use of a
Monte Carlo simulation allows the characterization of uncertainty
around final modeling outputs based on the uncertainty underlying the
various valuation inputs. The Stage 2 DBPR benefits model uses
distributions of value of statistical life (VSL), willingness-to-pay
(WTP), and income elasticity values to attribute monetary values (with
uncertainty bounds) to the number of bladder cancer cases avoided.
Several of the inputs needed in the benefit analysis, such as the
VSL and WTP estimates, are based on older studies that were updated to
current dollar values. In addition, both the VSL and WTP values are
dependent on income levels. Therefore, these values also have to be
adjusted for increases in real income growth from when the studies were
conducted. The valuation inputs and an explanation of the update
factors used to bring these values to current price levels and
discussed in the following two sections.
Valuation inputs. In order to monetize the benefit from the bladder
cancer fatalities, EPA applied a VSL estimate to the cancer cases that
result in mortality. EPA assumed a 26 percent mortality rate for
bladder cancer (USEPA 1999d). The Agency uses a distribution of VSL
values which are based on 26 wage-risk studies. The mean VSL value from
these studies is $4.8 million in 1990 dollars. The mean value reflects
the best estimate in the range of plausible values reflected by the 26
studies. A more detailed discussion of these studies and the VSL
estimate can be found in EPA's Guidelines for Preparing Economic
Analyses (USEPA 2000b).
The VSL represents the value of reducing the risk of a premature
death. This valuation, however, does not take into account the medical
costs associated with the period of illness (morbidity increment)
leading up to a death. In its review of the Arsenic Rule, the Science
Advisory Board (SAB) suggested that the appropriate measure to use in
valuing the avoidance of the morbidity increment is the medical cost
attributable to a cancer case (USEPA 2001e). Based on available medical
data, EPA estimates the medical costs for a fatal bladder cancer case
to be $93,927 at a 1996 price level (USEPA 1999d). This medical cost
value (updated to 2000 price levels) is applied as a point

[[Page 49631]]

estimate to each fatal case of bladder cancer in the benefits model.
A review of the available literature did not reveal any studies
that specifically measured the WTP to avoid risks of contracting
nonfatal cases of bladder cancer. Instead, two alternates were used,
the WTP to avoid the risk of contracting a case of curable lymph cancer
(lymphoma) and the WTP to avoid a case of chronic bronchitis. The SAB
suggested this approach in their review of the Arsenic Rule (USEPA
2001e). The median risk-risk trade-off for a curable case of lymphoma
was equivalent to 58.3 percent of the risk attributed to reducing the
chances of facing a sudden death and are derived from the Magat et al.
study (1996). Therefore, the Agency applies the 58.3 percent to the VSL
distribution to derive a range of value for non-fatal cancers with a
mean WTP value of $2.8 million ($4.8 million * 58.3 percent) at a 1990
price level. The WTP for avoiding a case of chronic bronchitis is based
on the same methodology used for the Stage 1 DBPR (see Stage 2 DBPR EA
(USEPA 2003i) for a complete discussion). The estimate is based on a
lognormal distribution that uses the risk-dollar tradeoff estimate and
has a mean of $587,500, standard deviation of $264,826, and a maximum
value of $1.5 million at 1998 price values.
Update factors. All valuation parameters must be updated to the
same price level so comparisons can be made in real terms. Values for
VSL, WTP, and the morbidity increment used in the model are updated
based on adjustment factors derived from Bureau of Labor Statistics
(BLS) consumer price index (CPI) data so that each represents a year
2000 price level. Table VII-4 summarizes these updates.
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Although the price level (year 2000) is held constant throughout
the benefits model, projections of benefits in future years are subject
to income elasticity adjustments. Income elasticity adjustments
represent changes in valuation in relation to changes in real income.
For fatal cancers, the Agency used a triangular distribution with a
central estimate of 0.40 (low end: 0.08; high end:1.00) to represent
the uncertainty of the income elasticity value. For non-fatal cancers,
the Agency uses a triangular distribution with a central estimate of
0.45 (low end: 0.25; high end: 0.60). These distributions are used as
assumptions in the Monte Carlo simulation to further characterize
uncertainty in benefits estimates.
In order to apply the income elasticity values in the model, they
are combined with projections of real income growth over the time frame
for analysis. Population and real gross domestic product (GDP)
projections are combined to calculate per-capita real GDP values. A
more detailed discussion of these adjustments is in Chapter 5 of the EA
(USEPA 2003i).
The development of cancer due to exposure to environmental
carcinogens involves a complex set of processes that are not well-
understood for most specific substances. In general, however, the
development of cancer involves some time period, usually referred to as
the latency period, between the initial exposure and the manifestation
of disease. Defining a latency period is highly uncertain because the
mode of action for most chemical contaminants are poorly understood.
Latency periods in humans often involve many years, even decades.
EPA recognizes that despite uncertainties in the latency period
associated with different types of carcinogens, it is unlikely that all
cancer reduction benefits would be realized immediately upon exposure
reduction. If it is assumed that lower risk is attained immediately
upon reduction in exposure, this would tend to overestimate the
benefits. On the other hand, assuming that no risk reduction occurs for
some period of time following exposure reduction may lead to an
underestimation of the benefits. There will likely be some transition
period as individual risks become more reflective of the new lower
exposures than the past higher exposures.
Recently, the Arsenic Rule Benefits Review Panel of the EPA Science
Advisory Board (SAB) addressed this issue in detail and provided some
guidance for computing benefits to account for this transition period
between higher and lower steady-state risks (USEPA 2003s). The Arsenic
Rule Benefits Review Panel coined the term ``cessation-lag'' to
emphasize the focus on the timing of the attenuation of risk after
reduction in exposures to avoid confusion with the more traditional
term of ``latency'' that reflects the increased risk \4\ from the time
of initial exposure.
---------------------------------------------------------------------------

\4\ SAB included the following in its report on arsenic to
emphasize this difference: ``An important point is that the time to
benefits from reducing arsenic in drinking water may not equal the
estimated time since first exposure to an adverse effect. A good
example is cigarette smoking: the latency between initiation of
exposure and an increase in lung cancer risk is approximately 20
years. However, after cessation of exposure, risk for lung cancer
begins to decline rather quickly. A benefits analysis of smoking
cessation programs based on the observed latency would greatly
underestimate the actual benefits.''

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[[Page 49632]]

Although the focus of the cessation lag discussion in the SAB
review was on reducing levels of arsenic in drinking water, much of
their consideration of this issue has more general applications beyond
just the arsenic issue at hand. In particular, SAB noted the following:
? The same model should be used to estimate the time pattern
of exposure and response as is used to estimate the potency of the
carcinogen.
? If possible, information about the mechanism by which
cancer occurs should be used in estimating the cessation lag (noting
that late-stage mechanisms in cancer formation imply a shorter
cessation lag than early stage mechanisms).
? If specific data are not available for characterizing the
cessation lag, an upper bound for benefits can be provided based on the
assumption of immediately attaining steady-state results.
? In the absence of specific cessation lag data, other models
should be considered to examine the influence of the lag.
Following the release of the SAB report on arsenic, EPA initiated
an effort to explore approaches to including the cessation lag in
modeling risk reduction and calculating benefits for the arsenic
regulation. EPA recognized, however, that the concept of cessation lag
is not only applicable to arsenic but to other drinking water
contaminants having a cancer end-point as well.
In response to the SAB cessation lag recommendations, EPA has:
? Conducted a study using data on lung cancer risk reductions
following cessation of smoking that resulted in the January 2003 report
Arsenic in Drinking Water: Cessation Lag Model (USEPA 2003s).
? Conducted an expert scientific peer review of that draft
report.
? Initiated development of general criteria for incorporating
cessation lag modeling in benefits analyses for other drinking water
regulations.
In the effort to develop a cessation lag model specific to DBPs,
EPA reviewed the available epidemiological literature for information
relating to the timing of exposure and response, but could not identify
any studies that were adequate, alone or in combination, to support a
specific cessation lag model for DBPs in drinking water. Thus, in
keeping with the SAB recommendation to consider other models in the
absence of specific cessation lag information, EPA explored the use of
information on other carcinogens that could be used as a indicator to
characterize the influence of cessation lag in calculating benefits.
The carcinogen for which the most extensive database was available for
characterizing cessation lag was for cigarette smoking. EPA examined
several extensive epidemiological studies on the comparison of the
risks of adverse health effects, including lung cancer, for smokers and
former smokers. EPA selected the Hrubek and McLaughlin (1997) study as
the most appropriate study for development of a statistical model of
disease response to smoking cessation. This was a comprehensive study
involving a 26-year follow-up of almost 300,000 U.S. male military
veterans. More detail about this study and how it is applied to
estimate the cessation lag can be found in Chapter 5 of the EA (USEPA
2003i) and the cessation lag document (USEPA 2003s).
The smoking cessation lag data imply that the majority of the
potential steady state cases avoided occur within the first several
years, but with diminishing incremental increases in later years. For
example, the cessation lag model indicates that approximately 40
percent of the steady-state cases avoided are achieved by the end of
the second year, with 70 percent achieved by the end of the fifth year,
and approximately 80 percent by the tenth year. By the twentieth year,
90 percent of the steady state cases are avoided.
EPA recognizes that there are several factors that contribute to
the uncertainty in the application of the specific cessation lag model
used in the estimation of the benefits of the proposed Stage 2
regulation. A key factor to consider in assessing this impact is the
likely mode of action of DBPs in eliciting bladder cancer versus the
mode of action of tobacco smoke in producing lung cancer, and in
particular whether they behave as initiators or promoters of the
carcinogenic process. As discussed in the SAB report and the EPA
Cessation Lag report (USEPA 2001e, USEPA 2003s), carcinogens that act
solely or primarily as initiators would tend to show a longer cessation
lag (lower rate of risk reduction following reductions in exposure)
than carcinogens that act solely or primarily as promoters. The
available information on tobacco smoke and lung cancer suggests that it
involves a mixture of both initiators and promoters, and therefore the
cessation lag derived from smoking data is expected to reflect the
combined influence of these divergent mechanisms. There are no data
available on the mechanism of action for DBPs and bladder cancer;
indeed the specific carcinogenic agent(s) present in disinfected water
responsible for the observed effect have not been identified. The use
of the tobacco smoke cessation lag model reflecting a mixture of
initiators and promoters would be expected to attenuate a possible bias
in either direction if the DBPs responsible for bladder cancer are
acting predominately as either initiators or promoters.
Another factor to consider is that the cessation lag model used is
based upon exposure to tobacco smoke where lung cancer is the end-point
but is being applied to exposure to disinfection by-products where the
end-point is bladder cancer. Of concern here is that there is a more
direct correlation between inhalation and the site of cancer for
smoking than there is for ingestion and inhalation of drinking water
and the sites of cancer for DBP exposure. Unfortunately, EPA does not
have data on which to develop a cessation lag model using data specific
to how changes in DBP exposures affect the risks of developing bladder
cancer.
Another divergence, and perhaps the most important, between the
smoking model and the DBP application is that the smoking model is
based on complete cessation of exposure, whereas in the case of DBP
exposure is only being reduced. In some water systems the reduction is
only 10 percent, whereas in others it may be as high as 60 percent,
with an average of approximately 30%. This moderate reduction in
exposure may prevent full DNA repair, which some scientists interpret
as the basis for the short cessation lag associated with smoking.
Currently, smoking is the only contaminant for which enough data
exist to estimate a cessation lag. In the absence of a reliable
cessation lag model based specifically on DBPs and bladder cancer, EPA
used the cessation lag model based on smoking to provide a means of
estimating the rate at which bladder cancer risk in the exposed
population falls from the pre-Stage 2 levels to the post-Stage 2
levels. However, this model is derived from data involving notable
differences from DBPs in drinking water, including different cancer
sites (lung versus bladder), different exposure pathways (inhalation
versus a combination of ingestion, inhalation and dermal), different
risk levels, and, perhaps most importantly, complete cessation for
smoking versus small exposure decreases for DBPs. For these reasons,
the extent to which the smoking / lung cancer model is directly
transferable to DBP / bladder cancer is uncertain. It is not possible
to know, however, whether and to what degree the tobacco smoke

[[Page 49633]]

cessation lag model either over-states or under-states the rate at
which population risk reduction for bladder cancer occurs following DBP
exposure reductions.
EPA is currently examining the recently published meta-analysis by
Villanueva et al. (2003) to determine if the information provided on
increases in risk as a function of duration of exposure can provide any
insight on how reductions in risk over time might occur following
reductions in exposure. Villanueva et al. (2003) demonstrated that the
risk associated with chlorinated drinking water and bladder cancer are
related to exposure duration. Specifically, they estimated a unit
increase in the odds ratio of 1.006 per year (95% CI of 1.004 to
1.009). The model suggests a cumulative odds ratio of 1.13 after 20
years of exposure (95% CI of 1.08 to 1.20), and 1.27 (95% CI of 1.17 to
1.43) after 40 years. This result is consistent with most of the
individual studies which do not show statistically significant risk
increases until at least 30-40 years of exposure. However, these
studies provide indirect evidence only about the latency of potential
effects. For perspective, it is important to note that the latency
between initiation of exposure and an increase in lung cancer risk is
approximately 20 years. As noted above, latency is not the same as the
cessation lag. EPA is requesting comment on (a) the potential
application of the Villanueva et al. (2003) model to estimate
reductions in bladder cancer risk that might accompany decreased
exposure to DBPs as a result of the Stage 2 Rule; (b) the advantages
and disadvantages of using the current approach--i.e., application of
the smoking cessation lag model; and (c) suggestions for alternative
data sets or approaches to characterize cessation lag.
In addition to the delay in reaching a new steady-state level of
risk reduction as a result of cessation lag effects, there is a delay
in exposure reduction resulting from the Stage 2 DBPR implementation.
In general, EPA assumes that a fairly uniform increment of systems will
complete installation of new treatment technologies each year, with the
last systems installing treatment by 2013. EPA recognizes that more
systems may start in early or later years, but believes that a uniform
schedule is a reasonable assumption. Appendix D of the EA presents
detailed information regarding the rule activity schedule assumptions
(USEPA 2003i).
The delay in exposure reduction resulting from the rule
implementation schedule is incorporated into the benefits model by
adjusting the cessation lag weighting factor. For example, if ten
percent of systems install treatment equipment (and start realizing
reductions in cancer cases) in year one, only that portion of the cases
are modeled to begin the cessation lag equilibrium process in that
year. Thus, the resulting ``weighted weighting factor'' is higher
relative to the base factor. Appendix E in the EA (USEPA 2003i)
presents detailed breakdowns of all weighting factor adjustments and
resulting cancer cases avoided, by year, for each rule alternative
based on the application of the cessation lag methodology.
3. Benefit Sensitivity Analyses
The Agency performed one other benefit sensitivity analysis which
is included in the EA to allow for comparison with the benefit
estimates calculated for the Stage 1 DBPR. This analysis assumes that
there is not a cessation lag or latency adjustment associated with
bladder cancer reductions that result from the rule. In this case, the
analysis assumes that the steady state reduction in bladder cancer
occurs immediately with rule implementation. This is the same
methodology used to estimate the quantified benefits of the Stage 1
DBPR.

D. Costs of the Proposed Stage 2 DBPR

In estimating the costs of today's proposed rule, the Agency
considered impacts on water systems (CWSs and NTNCWSs) and on States
(including territories and EPA implementation in non-primacy States).
EPA assumed that systems would be in compliance with the Stage 1 DBPR,
which has a compliance date of January 2004 for ground water systems
and small surface water systems and January 2002 for large surface
water systems. Therefore, the cost estimate only considers the
additional requirements that are a direct result of the Stage 2 DBPR.
More detailed information on cost estimates are described later and a
complete discussion can be found in Chapter 6 of the Stage 2 DBPR EA
(USEPA 2003i)
1. National cost estimates
EPA estimates that the mean annualized cost of the proposed rule
ranges from approximately $59.1 million using a three percent discount
rate to $64.6 million using a seven percent discount rate. Drinking
water utilities will incur approximately 98 percent of the rule's
costs. States will incur the remaining rule cost. Tables VII-5 a and b
summarize the total annualized cost estimates for the proposed Stage 2
DBPR. In addition to mean estimates of costs, the Agency calculated 90
percent confidence bounds by considering the uncertainty around the
mean unit technology costs. Table VII-6 shows the undiscounted capital
cost and all one-time costs broken out by rule component. A table
comparing total annualized costs among the regulatory alternatives
considered by the Agency is located in subsection VII.G.
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2. Water system costs
The proposed Stage 2 DBPR applies to all community or nontransient
noncommunity water systems that add a chemical disinfectant other than
UV or distribute water that has been treated with a disinfectant other
than UV. EPA has estimated the cost impacts for both types of public
water systems. As shown in Tables VII-5 a and b, the total annualized
present value costs for CWSs is approximately $55.8 million and for
NTNCWSs, $2.2 million, using a three percent discount rate ($60.8
million and $2.2 million using a seven percent discount rate).
Although the number of systems adding treatment is small, treatment
costs make up a significant portion of the total costs of the rule
(more than 75 percent of total rule costs). Table VII-7 shows the
baseline number of plants and the estimated percent of those plants
adding treatment. The estimated percent of plants adding advanced
treatment or converting to chloramines is 2.8 percent of all systems. A
higher percentage of surface water plants are predicted to add
treatment compared to ground water plants. However, the baseline number
of ground water plants is larger than that of surface water plants, so
there is a larger number of ground water plants adding treatment.
Subsection VII.F. provides a more detailed explanation of treatment
changes that may occur as a result of the proposed rule.
All systems will incur costs for rule implementation. Some will
need to conduct a one-time Initial Distribution System Evaluation
(IDSE) and others (a different subgroup depending on the system size)
may incur additional costs for routine DBP monitoring. Some systems may
also have to conduct a peak excursion evaluation if single samples
indicate high DBP levels.
Sixty-nine percent of surface water and 7 percent of ground water
CWSs are predicted to conduct the IDSE monitoring. EPA estimates that a
very small portion of systems (approximately 16 percent overall) will
conduct additional routine monitoring beyond the Stage 1 DBPR
requirements. However, fewer samples overall would be required if a
population-based approach is implemented instead of the plant-based
approach that is currently being used to estimate monitoring costs.
Section V describes the population-based approach in more detail and a
discussion of how this approach may influence costs is provided in
Appendix H of the EA (USEPA 2003i). A small percentage of systems
(approximately 3.0 percent of surface water CWSs and 0 percent of
ground water systems) are expected to experience significant
excursions.
A complete discussion of the rule provisions is located in section
V of this preamble; the Stage 2 DBPR Economic Analysis includes a
complete analysis of rule impacts (USEPA 2003i). Table VII-8 summarizes
the number of systems subject to non-treatment related rule activities.
Column D indicates the number of systems expected to use the standard
monitoring program to implement the IDSE. Column F indicates the number
of systems expected to increase monitoring sites beyond that required
by Stage 1. The last two columns show the number and percent of plants
estimated to experience significant excursions each year.

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[[Page 49640]]

In addition to using distributions to develop unit cost estimates,
the Agency conducted sensitivity analyses to further explore
uncertainty regarding system compliance estimates. The first two
sensitivity analyses were prepared to evaluate the possibility that the
IDSE monitoring requirement will result in more systems needing to
install treatment beyond what is predicted in the current cost model
(see chapter 7 of the EA, USEPA 2003i, for details of this analysis).
Table VII-9 lists the high-end estimates of the number of systems
adding treatment in IDSE sensitivity analyses No. 1 and No. 2. For both
IDSE sensitivity analyses, only small additional impacts were assumed
possible for systems serving 10,000 people or fewer because such
systems generally have much less complicated distribution systems than
larger systems. EPA estimated that the mean annualized costs at the 3%
discount rate could be as high as $77.5 million (IDSE Sensitivity
Analysis No. 1) or $108.8 million (IDSE Sensitivity Analysis No. 2)
versus the Preferred Alternative analysis estimate of $57.4 million. At
the 7% discount rate these estimates would respectively correspond to
$86.1 million, $120.7 million, and $63.3 million.
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EPA believes that the percentage of systems estimated to add
treatment under IDSE sensitivity analyses No. 1 and No. 2 are
overestimates and that the estimate for the Preferred Alternative is
likely to already capture the influence of the IDSE because of the
conservative assumptions used in the analysis. For example, the
compliance forecast analysis assumes that systems will try to meet the
LRAA MCLs with a 20% margin of safety. Systems complying by switching
to chloramines may choose to meet the new MCLs with a much smaller
margin of safety since chloramines dampen the variability of DBP
concentrations within the distribution system. Furthermore, EPA
believes that the number of ground water and small surface water
systems adding chloramines or changing technology in the baseline
analysis may be overestimated because their monitoring requirements are
expected to be very similar from Stage 1 to Stage 2. The Stage 1 DBPR
required only one compliance monitoring location (at the point of
maximum residence time) for producing surface water systems serving
between 500 and 10,000 people and for all ground water systems. The
Stage 2 DBPR requires that these systems add an additional site if they
determine that their high TTHM and high HAA5 concentrations do not
occur at the same location. If systems maintain a single monitoring
location for the Stage 2 DBPR, as many are expected to do, calculation
of compliance will produce the same results for the running annual
average (RAA) and locational running annual average (LRAA) measure,
implying that they are not likely to add treatment for the Stage 2 DBPR
if they comply with the Stage 1 DBPR.
EPA conducted a third sensitivity analysis to evaluate the
possibility that small systems will continue to monitor at one point in
their distribution system. In this sensitivity analysis, EPA assumed
that no surface water plants serving fewer than 10,000 people and no
ground water plants would add treatment to meet Stage 2 DBPR
requirements (i.e., only costs are associated for large surface water
systems). Under this analysis, the average cost figures are reduced
dramatically from $57.4 million or $63.3 million to $22.9 million or
$25.7 million using a 3 percent or 7 percent discount rate,
respectively, for the Preferred Regulatory Alternative. Chapter 7 of
the Economic Analysis (USEPA 2003i) contains a detailed explanation of
the aforementioned sensitivity analysis.
3. State Costs
The Agency estimates that the States and primacy agencies will
incur an annualized present value cost of $1.1 million to $1.5 million
(using a three percent and seven percent discount rate, respectively).
In order to estimate the cost impact to States, EPA considered initial
implementation costs, costs for assisting systems in evaluating IDSE
information, and for annual rule implementation activities. EPA
considered the incremental change in activities that result from the
Stage 2 DBPR. For example, States may have to update their databases to
track the new Stage 2 DBPR monitoring strategy but could modify the
system they developed for the Stage 1 DBPR. EPA accounted for the cost
of a Stage 1 DBPR database in the Stage 1 Regulatory Impact Analysis
(USEPA 1998f). State costs are not expected to change dramatically
between alternatives.
4. Non-quantifiable
EPA has identified and quantified costs that it believes are likely
to be significant. In some instances, EPA did not include a potential
cost element because it believes the effects are relatively minor and
difficult to estimate. For example, the Stage 2 DBPR may be the
determining factor in the decision by some small water systems to merge
with neighboring systems. Such changes have both costs (legal fees and
connecting infrastructure) and benefits (economies of scale). Likewise,
costs for procuring a new source of water would have costs for new
infrastructure but could result in lower treatment costs.
Also, EPA was unable to quantify several distribution system-
related

[[Page 49641]]

changes that can reduce TTHM and HAA5 levels. Activities such as
looping distribution systems and optimizing storage can minimize
retention times and help to control DBP formation. Costs for these
activities range from almost zero (modifying retention time) to more
substantial costs for modifying distribution systems. In the absence of
detailed information needed to make cost evaluations for situations
such as these, EPA has included a discussion of possible effects where
appropriate.

E. Expected System Treatment Changes

In order to quantify the effects of the Stage 2 DBPR, it is
necessary to predict how plants will modify their treatment processes
to meet the proposed requirements. To estimate the incremental impacts
of the Stage 2 DBPR, relative to the Stage 1 DBPR, EPA compared
predicted ``ending technologies'' (types of treatment in use after
implementation of the Stage 2 DBPR) to the distribution of baseline
technologies predicted to be in place after the implementation of the
Stage 1 DBPR. This subsection outlines the process for deriving
baseline and ending Stage 2 technology distributions that are the basis
for the national cost estimates of today's proposed rule.
1. Pre-Stage 2 DBPR Baseline Conditions
Development of the Pre-Stage 2 baseline (i.e., conditions following
the Stage 1 DBPR) consists of the following processes:
? Compiling an industry profile--identifying and collecting
information on the segment(s) of the water supply industry subject to
the Stage 2 DBPR;
? Characterizing influent water quality--summarizing the
relevant characteristics of the raw water treated by the industry; and
? Characterizing treatment for the Stage 1 DBPR--predicting
what the industry will do to comply with the provisions of the Stage 1
DBPR.
Section IV of this document details the data sources EPA used to
characterize water quality and treatment practices for the nation's
public water systems. EPA also used information in the Water Industry
Baseline Handbook (USEPA 2000j) to develop the industry profile. The
Baseline Handbook uses data derived from the 1995 Community Water
Systems Survey and the Safe Drinking Water Information System to
characterize the U.S. drinking water systems. Another EPA study,
Geometries and Characteristics of Water Systems Report (USEPA 2000k),
also provided information for the industry profile.
EPA developed and used a model (SWAT) to characterize treatment
following the Stage 1 DBPR and Stage 2 DBPR options considered. SWAT
served as the primary tool to predict changes in treatment and DBP
occurrence. The model used a series of algorithms and decision rules to
predict the type of treatment a large surface water plant will use
given a specific regulatory alternative and source water quality. Other
tools were used to estimate practices at large ground water systems or
any medium or small systems. A Delphi process (a detailed technical
treatment characterization and DBP occurrence review by drinking water
experts) was used to predict treatment changes for large ground water
systems (those serving 10,000 or more people). The results of the SWAT
analyses and the Delphi process were extrapolated to the medium surface
water and ground water systems based on analysis of source water
treatment characteristics and treatment decision trees. For the small
surface and ground water systems analyses, a group of experts provided
predictions for a pre-Stage 2 baseline and resulting treatment and
water quality conditions under the Stage 2 DBPR regulatory
alternatives. A detailed description of these analyses can be found in
the Economic Analysis for the Stage 2 DBPR (USEPA 2003i).
2. Predicted Technology Distributions Post-Stage 2 DBPR
The treatment compliance forecast for the Stage 2 DBPR has two
components--1) the percent of plants that must add treatment to comply
with Stage 2 DBPR requirements, and 2) the treatment technologies these
plants are predicted to select. This information, coupled with the
baseline data discussed before, provides an estimate of the total
number of plants using specific technologies to meet the requirements
of the proposed Stage 2 DBPR. National costs are then generated using
technology unit cost information.
The four step process EPA used to develop a Stage 2 DBPR compliance
forecast is summarized in table VII-10. The difference between the
Stage 1 DBPR Technology Selections and Stage 2 DBPR Technology
Selections (Step 4--Incremental Technology Selections) was used to
develop national cost estimates for today's proposed rule. Tables VII-
11 a and b (surface water) and VII-12 a and b (ground water) show the
incremental technology selections shown as the percent change between
Stage 1 and Stage 2 DBP rules.

Table VII-10.--Stage 2 DBPR Compliance Forecast Summary
------------------------------------------------------------------------
Step Description of Step
------------------------------------------------------------------------
1............................... Model a pre-Stage 1 baseline scenario
using Information Collection Rule
data to allow consistent comparison
between different rule alternatives.
2............................... Model technology selection to meet
Stage 1 DBPR requirements (Stage 1
DBPR Technology Selection).
3............................... Model technology selection to meet
Stage 2 DBPR requirements (Stage 2
DBPR Technology Selection).
4............................... Subtract the results in Step 2 from
Step 3 and adjust to obtain the
incremental impact of an alternative
(Stage 2 DBPR incremental technology
selection).
------------------------------------------------------------------------

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F. Estimated Household Costs of the Proposed Rule

This analysis considers the potential increase in a household's
water bill if a system passed the entire cost increase resulting from
this rule on to their customers. It is a tool to gauge potential
impacts and should not be construed as precise estimates of potential
changes to individual water bills.
Overall, the potential increase in mean annual water bill per
household is estimated to be $8.38 for those systems that need to
install technology to comply with this rule. Table VII-13 shows the
range of household costs for all surface and ground water systems
subject to the rule and also only for those systems installing
technology to comply with this rule. For all systems, including those
that may not have to take any additional action to comply with this
rule but are still subject to its provisions, the mean annual household
cost is $0.51. The last two columns of Table VII-13 show the potential
impact as the percent of households that will incur either less than a
$1 or less than a $10 increase in their monthly water bills (shown in
the table as annual values). For systems adding treatment, 84% of
households will face less than a $1 increase in their monthly bill,
while 99% are expected to face less than a $10 increase.

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Both household cost estimates reflect costs for rule implementation
(e.g., reading and understanding the rule), IDSE, additional routine
monitoring, and treatment changes. Although implementation and the IDSE
represent relatively small, one-time costs, they have been annualized
and included in the analysis to provide a complete picture of household
costs.
Overall, EPA estimates that 99 percent of the 98 million households
that are provided disinfected drinking water would face less than $1
increase in their monthly water bill. Approximately 86 percent of the
households impacted by the rule are served by systems serving at least
10,000 people; these systems experience the lowest increases in costs
due to significant economies of scale. Households served by small
systems that install advanced technologies will face the greatest
increases in annual costs. The cumulative distributions of household
costs for all systems are presented in the Economic Analysis (USEPA
2003i).
When interpreting the results of the household cost analysis, it is
important to remember that systems, especially small systems, may have
other options that were not included in the compliance forecast. For
example, the system may identify another water source that may form
lower levels of TTHM and HAA5. Systems that can identify such an
alternate water source may not have to treat that water as much as
their current source, resulting in lower treatment costs that may
offset the costs of obtaining water from the alternate source. Systems
may also be able to connect to a neighboring water system. While
connecting to another system may not be feasible for some remote
systems, EPA estimates that more than 22 percent of all small water
systems are located within metropolitan regions (USEPA 2000c) where
distances between potential connecting water systems may not present a
prohibitive barrier. Consolidation was not an element used in
developing the compliance forecasts for small systems. Costs for
consolidation may be either greater or less than the costs for changing
technologies, and consolidation may have other benefits (e.g., lower
costs for compliance with future regulations). In addition, potentially
lower cost alternatives such as controlling water residence time in the
distribution systems were not included in the compliance forecast.
Also, more small systems than projected in the primary analysis may
already be in compliance with Stage 2 DBPR. A sensitivity analysis
discussed in the subsection VII.D.2 describes this issue in more
detail. Also, certain technologies installed to treat DBPs may treat
many other contaminants thus eliminating the need to install additional
equipment to comply with future drinking water regulations.

G. Incremental Costs and Benefits of the Proposed Stage 2 DBPR

Incremental costs and benefits are those that are incurred or
realized in reducing DBP exposures from one alternative to the next
more stringent alternative. Estimates of incremental costs and benefits
are useful in considering the economic efficiency of different
regulatory options considered by the Agency. However, as pointed out by
the Environmental Economics Advisory Committee of the Science Advisory
Board, efficiency is not the only appropriate criterion for social
decision making (USEPA 2000n).
Generally, the goal of an incremental analysis is to identify the
regulatory option where net social benefits are maximized. If net
incremental benefits

[[Page 49645]]

are positive, society is incurring greater costs as a result of the
health damages compared to the costs society could pay to reduce those
health damages (i.e. society would be better off to invest more in
controlling the health damage). If net incremental benefits are
negative, than the cost of the additional control is higher than the
value of the additional health damages avoided. Therefore, the
``efficient'' regulatory level is where the next additional incremental
reduction in health damages equals the incremental cost of achieving
that reduction. However, the usefulness of this analysis is constrained
when major benefits and/or costs are unquantified or not monetized.
For the proposed Stage 2 DBPR, presentation of incremental
quantitative benefit and cost comparisons may be unrepresentative of
the true net benefits of the rule because a significant portion of the
rule's potential benefits are non-quantifiable (see section C.1).
Tables VII-14 and VII-15 show the total estimated costs and benefits
for each alternative. Evaluation of the incremental changes between
different rows in the tables shows that incremental costs generally
fall within the range of incremental benefits for each more stringent
alternative. Equally important, the addition of any benefits
attributable to the non-quantified categories would add to the benefits
without any increase in costs.

Table VII-14.--Total Annualized Present Value Costs by Rule Alternative
($millions, 2000$)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total annualized cost ($millions)
-----------------------------------------------------------------------------------------------
3 Percent discount rate 7 Percent discount rate
-----------------------------------------------------------------------------------------------
Rule alternative 90 Percent confidence bound 90 Percent confidence bound
-------------------------------- -------------------------------
Mean estimate Lower (5th % Upper (95th % Mean estimate Lower (5th % Upper (95th %
tile) tile) tile) tile)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Preferred............................................... $59.1 $54.3 $63.9 $64.6 $59.2 $70.0
Alt. 1.................................................. 182.2 165.1 199.6 195.1 175.9 214.3
Alt. 2.................................................. 409.6 383.6 435.7 442.7 413.4 472.2
Alt. 3.................................................. 594.3 556.3 631.9 644.2 601.1 686.9
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Costs represent values in millions of 2000 dollars. Estimates are discounted to 2003--90 percent Confidence Intervals reflect uncertainty in
technology unit cost estimates
Source: Economic Analysis (USEPA 2003i) exhibit 6.24

[[Page 49646]]
[GRAPHIC]
[TIFF OMITTED]
TP18AU03.029

The range of quantified benefits increases significantly with
Alternatives 2 and 3. However, the associated costs also increase
significantly--cost figures presented in Table VII-14 show values
approaching or exceeding $500 million

[[Continued on page 49647]]

Notices For
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994

National Primary Drinking Water Regulations: Stage 2 Disinfectants and Disinfection Byproducts Rule; National Primary and Secondary Drinking Water Regulations: Approval of Analytical Methods for Chemical Contaminants [[pp. 49597-49646]]

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