EPA 815-Z-06 001
Thursday,
January 5, 2006
Part II
Environmental
Protection Agency
40 CFR Parts 9, 141, and 142
National Primary Drinking Water
Regulations: Long Term 2 Enhanced
Surface Water Treatment Rule; Final Rule
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4968
Corrections
Federal Register
Vol 71, No. 19
Monday, January 30, 2006
This section of the FEDERAL REGISTER
contains editorial corrections of previously
published Presidential, Rule, Proposed Rule,
and Notice documents. These corrections are
prepared by the Office of the Federal
Register Agency prepared corrections are
issued as signed documents and appear in
the appropriate document categories
elsewhere in the issue.
January 23, 2006, make the following
correction:
On page 3460, the table is corrected
in part to read as follows:
DEPARTMENT OF COMMERCE
International Trade Administration
[A-122-838]
Notice of Amended Final Results of
Antidumping Duty Administrative
Review; Certain Softwood Lumber
Products From Canada
Correction
In notice document E5-653 beginning
on page 3458 in the issue of Monday,
Producer/exporter
Original weighted-
average margin
(percentage)
Amended
weighted-average
margin
(percentage)
Buchanan (and its affiliates Atikokan Forest Products Ltd., Long Lake Forest Products Inc., Nakina
Forest Products Limited,9 Buchanan Distribution Inc., Buchanan Forest Products Ltd , Great West
Timber Ltd , Dubreuil Forest Products Ltd , Northern Sawmills Inc., McKenzie Forest Products Inc ,
Buchanan Northern Hardwoods Inc , Northern Wood, and Solid Wood Products Inc.)
Canfor10 (and its affiliates Canfor Wood Products Marketing Ltd., Canadian Forest Products, Ltd., Bois
Daaquam Inc. / Daaquam Lumber Inc., Lakeland Mills Ltd , The Pas Lumber Company Ltd. / Winton
Sales, Howe Sound Pulp and Paper Limited Partnership, Winton Global Lumber Ltd , and Skeena
Cellulose)
Tembec (and its affiliates Marks Lumber Ltd., Excel Forest Products, Les Industries Davidson Inc.,
Produits Forestiers Temrex Limited Partnership, Tembec Industries Inc , Spruce Falls Inc)
286
1 36
402
276
1.35
4.02
|FR Doc Z6-653 Filed 1-27-06; 8:45 am]
BILLING CODE 1505-01-D
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Parts 9,141, and 142
[EPA-HQ-OW-2002-0039; FRL-8013-1]
RIN 2040-AD37
National Primary Drinking Water
Regulations: Long Term 2 Enhanced
Surface Water Treatment Rule
Correction
In rule document 06-4 beginning on
page 654 in the issue of Thursday,
January 5, 2006. make the following
corrections:
1. On page 716, in Table IV.G-1, in
the third column, in the fifth entry, "No
later than October 1, 20133" should read
"No later than October 1, 20123".
2. On the same page, in the same
table, in the fourth column, in the fifth
entry, "No later than October 1, 20123"
should read "No later than October 1,
20133".
3. On the same page, in Table IV.G—
2, in the first column, in the fourth line,
"Report notice intent" should read
"Report notice of intent".
4. On page 724, in Table IV.J-1, in
footnote 8, in the first and second lines,
"enzyme glucuronidase" should read
"enzyme Pglucuronidase".
[FR Doc. C6-4 Filed 1-27-06; 8:45 am]
BILLING CODE 1505-01-D
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6136
Corrections
Federal Register
Vol. 71, No. 24
Mondav, February 6, 2006
This section of the FEDERAL REGISTER
contains editorial corrections of previously
published Presidential, Rule, Proposed Rule,
and Notice documents These corrections are
prepared by the Office of the Federal
Register. Agency prepared corrections are
issued as signed documents and appear in
the appropriate document categories
elsewhere in the issue.
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Parts 9,141, and 142
[EPA-HQ-OW-2002-0039; FRL-8013-1]
RIN 2040-AD37
National Primary Drinking Water
Regulations: Long Term 2 Enhanced
Surface Water Treatment Rule
Correction
In rule document 06^ beginning on
page 654 in the issue of Thursday,
January 5, 2006, make the following
correction:
§141.719 [Corrected]
On page 781, in §141.719(b)(v), in the
second column, the equation "LRV =
LOGio(Cf) x LOGio(Cp)" should read
"LRV = LOG,0(Q) - LOG,0(Cp)".
[FR Doc. C6-4 Filed 2-3-06; 8:45 am]
BILLING CODE 1505-01-D
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654
Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Parts 9,141, and 142
[EPA-HQ-OW-2002-0039; FRL-8013-1 ]
RIN 2040—AD37
National Primary Drinking Water
Regulations: Long Term 2 Enhanced
Surface Water Treatment Rule
AGENCY: Environmental Protection
Agency (EPA).
ACTION: Final rule.
SUMMARY: EPA is promulgating National
Primary Drinking Water Regulations
that require the use of treatment
techniques, along with monitoring,
reporting, and public notification
requirements, for all public water
systems that use surface water sources.
The purposes of the Long Term 2
Enhanced Surface Water Treatment Rule
(LT2ESWTR) are to protect public
health from illness due to
Cryptosporidium and other microbial
pathogens in drinking water and to
address risk-risk trade-offs with the
control of disinfection byproducts.
Key provisions in the LT2ESWTR
include the following: source water
monitoring for Cryptosporidium. with a
screening procedure to reduce
monitoring costs for small systems; risk-
targeted Cryptosporidium treatment by
filtered systems with the highest source
water Cryptosporidium levels;
inactivation of Cryptosporidium by all
unfiltered systems; criteria for the use of
Cryptosporidium treatment and control
processes; and covering or treating
uncovered finished water storage
facilities.
EPA believes that implementation of
the LT2ESWTR will significantly reduce
levels of infectious Cryptosporidium in
finished drinking water. This will
substantially lower rates of endemic
cryptosporidiosis, the illness caused by
Cryptosporidium, which can be severe
and sometimes fatal in sensitive
subpopulations (e.g., infants, people
writh weakened immune systems). In
addition, the treatment technique
requirements of this regulation will
increase protection against other
microbial pathogens like Giardia
lamblia.
DATES: This final rule is effective on
March 6, 2O06. The incorporation by
reference of certain publications listed
in the rule is approved by the Director
of the Federal Register as of March 6,
2006. For judicial review purposes, this
final rule is promulgated as of January
5, 2006.
ADDRESSES: EPA has established a
docket for this action under Docket ID
No. EPA-HQ-OW-2002-0039. All
documents in the docket are listed on
the www.regulations.gov Web site.
Although listed in the index, some
information is not publicly available,
i.e., CBI or other information whose
disclosure is restricted by statute.
Certain other material, such as
copyrighted material, is not placed on
the Internet and will be publicly
available only in hard copy form.
Publicly available docket materials are
available either electronical!}' through
www.regulations.gov or in hard copy at
the Water Docket, EPA/DC, EPA West,
Room B102, 1301 Constitution Ave..
NW., Washington, DC. The Public
Reading Room is open from 8:30 a.m. to
4:30 p.m., Monday through Friday,
excluding legal holidays. The telephone
number for the Public Reading Room is
(202) 566-1744, and the telephone
number for the Water Docket is (202)
566-2426.
FOR FURTHER INFORMATION CONTACT:
Daniel C. Schmelling, Standards and
Risk Management Division, Office of
Ground Water and Drinking Water (MC
4607M). Environmental Protection
Agency, 1200 Pennsylvania Ave., NW.,
Washington, DC 20460; telephone
number: (202) 564-5281: fax number:
(202) 564-3767; e-mail address:
schmelling.dan@epa.gov. For general
information, contact the Safe Drinking
Water Hotline, telephone number: (800)
426-4791. The Safe Drinking Water
Hotline is open Monday through Friday,
excluding legal holidays, from 9 a.m. to
5 p.m., Eastern time.
SUPPLEMENTARY INFORMATION:
I. General Information
A. Who Is Regulated by This Action?
Entities potentially regulated by the
LT2ESWTR are public water systems
(PWSs) that use surface water or ground
water under the direct influence of
surface water (GWUDI). Regulated
categories and entities are identified in
the following chart.
Industry
State Local
Category
Tribal or Federal Governments
Examples of regulated entities
Public Water Systems that use surface water or ground water under
the direct influence of surface water
Public Water Systems that use surface water or ground water under
the direct influence of surface water
This table is not intended to be
exhaustive, but rather provides a guide
for readers regarding entities likely to be
regulated by this action. This table lists
the types of entities that EPA is now
aware could potentially be regulated by
this action. Other types of entities not
listed in this table could also be
regulated. To determine whether your
facility is regulated by this action, you
should carefully examine the definition
of public water system in § 141.3 of
Title 40 of the Code of Federal
Regulations and applicability criteria in
§ 141.700(b) of today's rule. If you have
questions regarding the applicability of
the LT2ESWTR to a particular entity,
consult one of the persons listed in the
preceding section entitled FOR FURTHER
INFORMATION CONTACT.
Abbreviations Used in This Document
ASTM American Society for Testing
and Materials
AWWA American Water Works
Association
°C Degrees Centigrade
CDC Centers for Disease Control and
Prevention
CFE Combined Filter Effluent
CFR Code of Federal Regulations
COI Cost-of-Illness
CT The Residual Concentration of
Disinfectant (mg/L) Multiplied by the
Contact Time (in minutes)
CWS Community Water Systems
DAPI 4',6-Diamindino-2-phenylindole
DBFs Disinfection Byproducts
DBPR Disinfectants/Disinfection
Byproducts Rule
DE Diatomaceous Earth
DIG Differential Interference Contrast
(microscopy)
EA Economic Analysis
EPA United States Environmental
Protection Agency
GAG Granular Activated Carbon
GWUDI Ground Water Under the
Direct Influence of Surface Water
HAAS Five Haloacetic Acids
(Monochloroacetic, Dichloroacetic,
Trichloroacetic, Monobromoacetic
and Dibromoacetic Acids)
ICR Information Collection Rule (also
Information Collection Request)
ICRSS Information Collection Rule
Supplemental Surveys
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
655
ICRSSM Information Collection Rule
Supplemental Survey of Medium
Systems
ICRSSL Information Collection Rule
Supplemental Survey of Large
Systems
IESWTR Interim Enhanced Surface
Water Treatment Rule
Log Logarithm (common, base 10)
LRAA Locational Running Annual
Average
LRV Log Removal Value
LTlESWTR Long Term 1 Enhanced
Surface Water Treatment Rule
LT2ESWTR Long Term 2 Enhanced
Surface Water Treatment Rule
MCL Maximum Contaminant Level
MCLG Maximum Contaminant Level
Goal
MG Million Gallons
M-DBP Microbial and Disinfectants/
Disinfection Byproducts
MF Microfiltration
NPDWR National Primary Drinking
Water Regulation
NTTAA National Technology Transfer
and Advancement Act
NTU Nephelometric Turbidity Unit
OMB Office of Management and
Budget
PE Performance Evaluation
PWS Public Water System
QC Quality Control
QCRV Quality Control Release Value
RAA Running Annual Average
RFA Regulatory Flexibility Act
RO Reverse Osmosis
SAB Science Advisory Board
SBAR Small Business Advocacy
Review
SDWA Safe Drinking Water Act
SWAP Source Water Assessment
Program
SWTR Surface Water Treatment Rule
TCR Total Coliform Rule
TTHM Total Trihalomethanes
UF Ultrafiltration
UMRA Unfunded Mandates Reform
Act
Table of Contents
I. General Information
A. Who Is Regulated by This Action?
II. Summary of the Final Rule
A. Why Is EPA Promulgating the
LT2ESWTR?
B. What Does the LT2ESWTR Require?
1. Source water monitoring
2. Additional treatment for
Cryptosporidium
3. Uncovered finished water storage
facilities
C. Will This Regulation Apply to My Water
System?
III. Background Information
A. Statutory Requirements and Legal
Authority
B. Existing Regulations for Microbial
Pathogens in Drinking Water
1. Surface Water Treatment Rule
2. Total Coliform Rule
3. Interim Enhanced Surface Water
Treatment Rule
4. Long Term 1 Enhanced Surface Water
Treatment Rule
5. Filter Backwash Recycle Rule
C. Concern with Cryptosporidium in
Drinking Water
1. Introduction
2. What is Cryptosporidium?
3. Cryptosporidium health effects
4. Efficacy of water treatment processes on
Cryptosporidium
5. Epidemic and endemic disease from
Cryptosporidium
D. Specific Concerns Following the
IESWTR and LTlESWTR
E. New Information on Cryptosporidium
Risk Management
1. Infectivity
2. Occurrence
3 Analytical methods
4. Treatment
F. Federal Advisory Committee
Recommendations
IV. Explanation of Today's Action
A. Source Water Monitoring Requirements
1. Today's rule
a. Sampling parameters and frequency
b. Sampling location
c. Sampling schedule
d. Plants operating only part of the year
e. Failing to monitor
f. Providing treatment instead of
monitoring
g. Grandfathering previously collected data
h. Ongoing watershed assessment
i. Second round of monitoring
j. New source monitoring
2. Background and analysis
a. Sampling parameters and frequency
b. Sampling location
c. Sampling schedule
d. Plants operating only part of the year
e. Failing to monitor
f Grandfathering previously collected data
g. Ongoing watershed assessment
h. Second round of monitoring
3. Summary of major comments
a. Sampling parameters and frequency
b. Sampling location
c. Sampling schedule
d. Plants operating only part of the year
e. Failing to monitor
f. Providing treatment instead of
monitoring
g. Grandfathering previously collected data
h. Ongoing watershed assessment
i Second round of monitoring
j. New source monitoring
B. Filtered System Cryptosporidium
Treatment Requirements
1. Today's rule
a. Bin classification
b. Bin treatment requirements
2. Background and analysis
a. Basis for targeted treatment requirements
b. Basis for bin concentration ranges and
treatment requirements
3. Summary of major comments
C. Unfiltered System Cryptosporidium
Treatment Requirements
1 Today's rule
a. Determination of mean Cryptosporidium
level
b. Cryptosporidium treatment requirements
c. Use of two disinfectants
2. Background and analysis
a. Basis for Cryptosporidium treatment
requirements
b. Basis for requiring the use of two
disinfectants
c. Filtration avoidance
3. Summary of major comments
D. Options for Systems to Meet
Cryptosporidium Treatment
Requirements
1. Microbial toolbox overview
2. Watershed control program
a. Today's rule
b. Background and analysis
c. Summary of major comments
3. Alternative source
a. Today's rule
b. Background and analysis
c. Summary of major comments
4. Pre-sedimentation with coagulant
a. Today's rule
b Background and analysis
c. Summary of major comments
5. Two-stage lime softening
a. Today's rule
b. Background and analysis
c. Summary of major comments
6. Bank filtration
a. Today's rule
b. Background and analysis
c. Summary of ma|or comments
7. Combined filter performance
a. Today's rule
b. Background and analysis
c. Summary of major comments
8. Individual filter performance
a. Today's rule
b. Background and analysis
c. Summary of major comments
9. Demonstration of performance
a. Today's rule
b. Background and analysis
c. Summary of major comments
10. Bag and cartridge filtration
a. Today's rule
b. Background and analysis
c. Summary of ma]or comments
11. Membrane filtration
a. Today's rule
b. Background and analysis
c. Summary of major comments
12. Second stage filtration
a. Today's rule
b. Background and analysis
c. Summary of major comments
13. Slow sand filtration
a. Today's rule
b Background and analysis
c. Summary of major comments
14. Ozone and chlorine dioxide
a. Today's rule
b. Background and analysis
c. Summary of major comments
15. Ultraviolet light
a. Today's rule
b. Background and analysis
c. Summary of major comments
E. Disinfection Benchmarking for Giardia
lamblia and Viruses
1. Today's rule
2. Background and analysis
3. Summary of ma)or comments
F. Requirements for Systems with
Uncovered Finished Water Storage
Facilities
1. Today's rule
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Federal Register/ Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
2. Background and analysis
a. Types and sources of contaminants in
open reservoirs
b. Regulatory approaches to reduce risk
from contamination in open reservoirs
c. Definition of uncovered finished water
storage facility
3. Summary of major comments
G. Compliance Schedules
1. Today's rule
2. Background and analysis
3. Summary of major comments
H. Public Notice Requirements
1. Today's rule
2 Background and analysis
3. Summary of major comments
I. Reporting Source Water Monitoring
Results
1. Today's rule
2. Background and analysis
3. Summary of major comments
J. Analytical Methods
1. Analytical methods overview
2. Cryptosporidium methods
a. Today's rule
b Background and analysis
c. Summary of major comments
3. E. coli methods
a. Today's rule
b Background and analysis
c. Summary of major comments
4 Turbidity methods
a Today's rule
b. Background and analysis
c. Summary of major comments
K. Laboratory Approval
1. Cryptosporidium laboratory approval
a. Today's rule
b. Background and analysis
c. Summary of major comments
2. E. coli laboratory approval
a. Today's rule
b. Background and analysis
c. Summary of major comments
3. Turbidity analyst approval
a Today's rule
b Background and analysis
c. Summary of major comments
L. Requirements for Sanitary Surveys
Conducted by EPA
1. Today's rule
2. Background and analysis
3. Summary of major comments
M. Variances and Exemptions
1. Variances
2. Exemptions
V. State Implementation
A. Today's Rule
1. Special State primacy requirements
2. State recordkeeping requirements
3. State reporting requirements
4 Interim primacy
B. Background and Analysis
C. Summary of Major Comments
VI. Economic Analysis
A. What Regulatory Alternatives Did the
Agency Consider?
B What Analyses Support Today's Final
Rule?
C. What Are the Benefits of the
LT2ESWTR?
1. Nonquantified benefits
2. Quantified benefits
a Filtered PWSs
b. Unfiltered PWSs
3. Timing of benefits accrual (latency)
D. What Are the Costs of the LT2ESWTR?
1. Total annualized present value costs
2 PWS costs
a. Source water monitoring costs
b. Filtered PWSs treatment costs
c. Unfiltered PWSs treatment costs
d. Uncovered finished water storage
facilities
e. Future monitoring costs
f. Sensitivity analysis—influent bromide
levels on technology selection for filtered
plants
3. State/Primacy agency costs
4. Non-quantified costs
E. What Are the Household Costs of the
LT2ESWTR?
F. What Are the Incremental Costs and
Benefits of the LT2ESWTR?
H. Are there Increased Risks From Other
Contaminants?
I. What Are the Effects of the Contaminant
on the General Population and Groups
within the General Populations that Are
Identified as Likely to be at Greater Risk
of Adverse Health/Effects?
J. What Are the Uncertainties in the Risk.
Benefit, and Cost Estimates for the
LT2ESWTR?
K. What Is the Benefit/Cost Determination
for the LT2ESWTR?
L. Summary of Major Comments
1 Cryptosporidium occurrence
a. Quality of the ICR and ICRSS data sets
b. Treatment of observed zeros
2. Drinking water consumption
3. Cryptosporidium infectivity
4. Valuation of benefits
a. Valuation ol morbidity
b. Valuation of lost time under the
enhanced cost of illness (COI) approach
VII. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory
Planning and Review
B. Paperwork Reduction Act
C. Regulatory Flexibilitv Act
D. Unfunded Mandates Reform Act
E. Executive Order 13132- Federalism
F. Executive Order 13175. Consultation
and Coordination With Indian Tribal
Governments
G. Executive Order 13045: Protection of
Children from Environmental Health and
Safety Risks
H. Executive Order 13211: Actions that
Significantly Affect Energy Supply,
Distribution, or Use
I. National Technology Transfer and
Advancement Act
J. Executive Order 12898: Federal Actions
to Address Environmental Justice in
Minority Populations or Low-Income
Populations
K. Consultations with the Science
Advisory Board. National Drinking
Water Advisory Council, and the
Secretary of Health and Human Services
L. Plain Language
M. Analysis of the Likely Effect of
Compliance with the LT2ESWTR on the
Technical, Financial, and Managerial
Capacity of Public Water Systems
N. Congressional Review Act
VIII. References
II. Summary of the Final Rule
A. Whv Is EPA Promulgating the
LT2ESWTR?
EPA is promulgating the Long Term 2
Enhanced Surface Water Treatment Rule
(LT2ESWTR) to further protect public
health against Cryptosporidium and
other microbial pathogens in drinking
water. Cryptosporidium is a protozoan
parasite that is common in surface water
used as drinking water sources by
public water systems (PWSs). In
drinking water, Cryptosporidium is a
particular concern because it is highly
resistant to chemical disinfectants like
chlorine. When ingested,
Cryptosporidium can cause acute
gastrointestinal illness, which may be
severe and sometimes fatal for people
with weakened immune systems.
Cryptosporidium has been identified as
the cause of a number of waterborne
disease outbreaks in the United States
(details in section III.C).
The LT2ESWTR supplements existing
microbial treatment regulations and
targets PWSs with higher potential risk
from Cryptosporidium. Existing
regulations require most PWSs using
surface water sources to filter the water,
and those PWSs that are required to
filter must remove at least 99 percent (2-
log) of the Cryptosporidium (details in
section III.B). As explained in the
proposal for today's rule (68 FR 47640.
August 11. 2003) (USEPA 2003a), new
data on the occurrence, infectivity, and
treatment of Cryptosporidium in
drinking water indicate that existing
regulations are sufficient for most PWSs.
A subset of PWSs with greater
vulnerability to Cryptosporidium,
however, requires additional treatment.
In particular, recent national survey
data show that the level of
Cryptosporidium in the sources of most
filtered PWSs is lower than previously
estimated, but also that
Cryptosporidium levels vary widely
from source to source. Accordingly, a
subset of filtered PWSs has relatively
high levels of source water
Cryptosporidium contamination. In
addition, data from human health
studies indicate that the potential for
Cryptosporidium to cause infection is
likely greater than previously
recognized (details in section III.E).
These findings have led EPA to
conclude that existing requirements do
not provide adequate public health
protection in filtered PWSs with the
highest source water Cryptosporidium
levels. Consequently, EPA is
establishing risk-targeted additional
treatment requirements for such filtered
PWSs under the LT2ESWTR.
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For PWSs that use surface water
sources and are not required to filter
(i.e., unfiltered PWSs), existing
regulations do not require any treatment
for Cryptosporidium. New survey data
suggest that typical Cryptosporidium
levels in the treated water of unfiltered
PWSs are higher than in the treated
water of filtered PWSs (USEPA 2003a).
Thus, Cryptosporidium treatment by
unfiltered PWSs is needed to achieve
comparable public health protection
(details in section III.E). Further, results
from recent treatment studies have
allowed EPA to develop standards for
the inactivation of Cryptosporidium by
ozone, ultraviolet (UV) light, and
chlorine dioxide (details in section
IV.D). Based on these developments,
EPA is establishing requirements under
the LT2ESWTR for all unfiltered PWSs
to treat for Cryptosporidium, with the
required degree of treatment depending
on the source water contamination
level.
Additionally, the LT2ESWTR
addresses risks in uncovered finished
water storage facilities, in which treated
water can be subject to significant
contamination as a result of runoff, bird
and animal wastes, human activity,
algal growth, insects, fish, and airborne
deposition (details in section IV.F).
Existing regulations prohibit the
building of new uncovered finished
water storage facilities but do not deal
with existing ones. Under the
LT2ESWTR, PWSs must limit potential
risks by covering or treating the
discharge of such storage facilities.
Most of the requirements in today's
final LT2ESWTR reflect consensus"
recommendations from the Stage 2
Microbial and Disinfection Byproducts
(M-DBP) Federal Advisory Committee.
These recommendations are set forth in
the Stage 2 M-DBP Agreement in
Principle (65 FR 83015, December 29,
2000) (USEPA 2000a).
B. What Does the LT2ESWTR Require?
1. Source Water Monitoring
The LT2ESWTR requires PWSs using
surface water or ground water under the
direct influence (GWUDI) of surface
water to monitor their source water (i.e.,
the influent water entering the treatment
plant) to determine an average
Cryptosporidium level. As described in
the next section, monitoring results
determine the extent of
Cryptosporidium treatment
requirements under the LT2ESWTR.
Large PWSs (serving at least 10,000
people) must monitor for
Cryptosporidium (plus E. coli and
turbidity in filtered PWSs) for a period
of two years. To reduce monitoring
costs, small filtered PWSs (serving fewer
than 10,000 people) initially monitor
just for E. coli for one year as a
screening analysis and are required to
monitor for Cryptosporidium only if
their E. coli levels exceed specified
"trigger" values. Small filtered PWSs
that exceed the E. coli trigger, as well as
all small unfiltered PWSs, must monitor
for Cryptosporidium for one or two
years, depending on the sampling
frequency (details sections IV.A).
Under the LT2ESWTR, specific
criteria are set for sampling frequency
and schedule, sampling location, using
previously collected data (i.e.,
grandfathering), providing treatment
instead of monitoring, sampling by
PWSs that use surface water for only
part of the year, and monitoring of new
plants and sources (details in section
IV.A). The LT2ESWTR also establishes
requirements for reporting of monitoring
results (details in section IV.I), using
analytical methods (details in section
IV.J), and using approved laboratories
(details in section IV.K).
The date for PWSs to begin
monitoring is staggered by PWS size,
with smaller PWSs starting at a later
time than larger ones (details in section
IV.G). Today's rule also requires a
second round of monitoring to begin
approximately 6.5 years after the first
round concludes in order to determine
if source water quality has changed to
a degree that should affect treatment
requirements (details in section IV.A).
2. Additional Treatment for
Cryptosporidium
The LT2ESWTR establishes risk-
targeted treatment technique
requirements to control
Cryptosporidium in PWSs using surface
water or GWUDI. These treatment
requirements supplement those
established by existing regulations, all
of which remain in effect under the
LT2ESWTR.
Filtered PWSs will be classified in
one of four treatment categories (or
"bins") based on the results of the
source water Cryptosporidium
monitoring described in the previous
section. This bin classification
determines the degree of additional
Cryptosporidium treatment, if any, the
filtered PWS must provide. Occurrence
data indicate that the majority of filtered
PWSs will be classified in Bin 1, which
carries no additional treatment
requirements. PWSs classified in Bins 2,
3, or 4 must achieve 1.0- to 2.5-log of
treatment (i.e., 90 to 99.7 percent
reduction) for Crvptosporidium over
and above that provided with
conventional treatment. Different
additional treatment requirements may
apply to PWSs using other than
conventional treatment, such as direct
filtration, membranes, or cartridge filters
(details in section. IV.B). Filtered PWSs
must meet the additional
Cryptosporidium treatment required in
Bins 2, 3, or 4 by using one or more
treatment or control processes from a
"microbial toolbox" of options (details
in section. IV.D).
The LT2ESWTR requires all
unfiltered PWSs to provide at least 2-log
(i.e., 99 percent) inactivation of
Cryptosporidium. If the average source
water Cryptosporidium level exceeds
0.01 oocysts/L based on the monitoring
described in the previous section, the
unfiltered PWS must provide at least 3-
log (i.e.. 99.9 percent) inactivation of
Cryptosporidium. Further, under the
LT2ESWTR, unfiltered PWSs must
achieve their overall inactivation
requirements (including Giardia lamblia
and virus inactivation as established by
earlier regulations) using a minimum of
two disinfectants (details in section
IV.C).
3. Uncovered Finished Water Storage
Facilities
Under the LT2ESWTR, PWSs with
uncovered finished water storage
facilities must take steps to address
contamination risks. Existing
regulations require PWSs to cover all
new storage facilities for finished water
but do not address existing uncovered
finished water storage facilities. Under
the LT2ESWTR, PWSs using uncovered
finished water storage facilities must
either cover the storage facility or treat
the storage facility discharge to achieve
inactivation and/or removal of 4-log
virus, 3-log Giardia lamblia. and 2-log
Cryptosporidium on a State-approved
schedule (details in section. IV.F).
C. Will This Regulation Apply to My
Water System?
The LT2ESWTR applies to all PWSs
using surface water or GWUDI,
including both large and small PWSs,
community and non-community PWSs,
and non-transient and transient PWSs.
Wholesale PWSs must comply with the
requirements of today's rule based on
the population of the largest PWS in the
combined distribution system.
Consecutive PWSs that purchase treated
water from wholesale PWSs that fully
comply with the monitoring and
treatment requirements of the
LT2ESWTR are not required to take
additional steps for that water under
today's rule.
III. Background Information
The sections in this part provide
summary background information for
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today's final LT2ESWTR. Individual
sections address the following topics:
(A) Statutory requirements and legal
authority for the LT2ESWTR; (B)
existing regulations for microbial
pathogens in drinking water; (C) the
problem with Cryptosporidium in
drinking water; (D) specific public
health concerns addressed by the
LT2ESWTR; (E) new information for
Cryptosporidium risk management in
PWSs; and (F) recommendations from
the Stage 2 M-DBP Advisory Committee
for the LT2ESWTR. For additional
information on these topics, see the
proposed LT2ESWTR (USEPA 2003a)
and supporting technical material where
cited.
A. Statutory Requirements and Legal
Authority
The Safe Drinking Water Act (SDWA
or the Act), as amended in 1996.
requires EPA to publish a maximum
contaminant level goal (MCLG) and
promulgate a national primary drinking
water regulation (NPDWR) with
enforceable requirements for any
contaminant that the Administrator
determines may have an adverse effect
on the health of persons, is known to
occur or has a substantial likelihood of
occurring in public water systems
(PWSs) with a frequency and at levels
of public health concern, and for which,
in the sole judgement of the
Administrator, regulation of such
contaminant presents a meaningful
opportunity for health risk reduction for
persons served by PWSs (section 1412
MCLGs are non-enforceable health
goals and are to be set at a level at which
no known or anticipated adverse effects
on the health of persons occur and
which allows an adequate margin of
safety (sections 1412(b)(4) and
1412(a)(3)). EPA established an MCLG
of zero for Cryptosporidium under the
Interim Enhanced Surface Water
Treatment Rule (IESWTR) (63 FR 69478,
December 16, 1998) (USEPA 1998a). In
today's rule, the Agency is not making
any changes to the current MCLG for
Cryptosporidium.
The Act also requires each NPDWR
for which an MCLG is established to
specify a maximum contaminant level
(MCLJ that is as close to the MCLG as
is feasible (sections 1412(b)(4) and
1401(1)(Q). The Agency is authorized to
promulgate an NPDWR that requires the
use of a treatment technique in lieu of
establishing an MCL if the Agency finds
that it is not economically or
technologically feasible to ascertain the
level of the contaminant (sections
1412(b)(7)(A) and 1401(l)(Q). The Act
specifies that in such cases, the Agency
shall identify those treatment
techniques that would prevent known
or anticipated adverse effects on the
health of persons to the extent feasible
(section 1412(b)(7)(A)).
The Agency has concluded that it is
not currently economically or
technologically feasible for PWSs to
determine the level of Cryptosporidium
in finished drinking water for the
purpose of compliance with a finished
water standard. As described in section
IV.C, the LT2ESWTR is designed to
protect public health by lowering the
level of infectious Cryptosporidium in
finished drinking water to less than 1
oocyst/10,000 L. Approved
Cryptosporidium analytical methods,
which are described in section IV.K, are
not sufficient to routinely determine the
level of Cryptosporidium at this
concentration. Consequently, the
LT2ESWTR relies on treatment
technique requirements to reduce health
risks from Cryptosporidium in PWSs.
When proposing an NPDWR that
includes an MCL or treatment
technique, the Act requires EPA to
publish and seek public comment on an
analysis of health risk reduction and
costs. This includes an analysis of
quantifiable and nonquantifiable costs
and health risk reduction benefits,
incremental costs and benefits of each
alternative considered, the effects of the
contaminant upon sensitive
subpopulations (e.g.. infants, children,
pregnant women, the elderly, and
individuals with a history of serious
illness), any increased risk that may
occur as the result of compliance, and
other relevant factors (section
1412(b)(3)(C)). EPA's analysis of health
benefits and costs associated with the
LT2ESWTR is presented in the
Economic Analysis of the LT2ESWTR
(USEPA 2005a) and is summarized in
section VI of this preamble. The Act
does not, however, authorize the
Administrator to use a determination of
whether benefits justify costs to
establish an MCL or treatment technique
requirement for the control of
Cryptosporidium (section 1412(b)(6)(C)).
Finally, section 1412(b)(2)(C) of the
Act requires EPA to promulgate a Stage
2 Disinfectants and Disinfection
Byproducts Rule within 18 months after
promulgation of the LTlESWTR, which
occurred on January 14, 2002.
Consistent with statutory requirements
for risk balancing (section
1412(b)(5)(B)), EPA is finalizing the
LT2ESWTR in conjunction with the
Stage 2 DBPR to ensure parallel
protection from microbial and DBF
risks.
B. Existing Regulations for Microbial
Pathogens in Drinking Water
This section summarizes existing
rules that regulate treatment for
pathogenic microorganisms by PWSs
using surface water sources. The
LT2ESWTR supplements these rules
with additional risk-targeted
requirements, but does not withdraw
any existing requirements.
1. Surface Water Treatment Rule
The Surface Water Treatment Rule
(SWTR) (54 FR 27486, June 29, 1989)
(USEPA 1989a) applies to all PWSs
using surface water or ground water
under the direct influence (GWUDI) of
surface water as sources (i.e., Subpart H
PWSs). It established MCLGs of zero for
Giardia lamblia, viruses, and Legionella,
and includes the following treatment
technique requirements to reduce
exposure to pathogenic microorganisms:
(1) Filtration, unless specific avoidance
criteria are met; (2) maintenance of a
disinfectant residual in the distribution
system; (3) removal and/or inactivation
of 3-log (99.9%) of Giardia lamblia and
4-log (99.99%) of viruses; (4) maximum
allowable turbidity in the combined
filter effluent (CFE) of 5 nephelometric
turbidity units (NTU) and 95th
percentile CFE turbidity of 0.5 NTU or
less for plants using conventional
treatment or direct filtration (with
different standards for other filtration
technologies); and (5) watershed
protection and source water quality
requirements for unfiltered PWSs.
2. Total Coliform Rule
The Total Coliform Rule (TCR) (54 FR
27544, June 29, 1989) (USEPA 1989b)
applies to all PWSs. It established an
MCLG of zero for total and fecal
coliform bacteria and an MCL based on
the percentage of positive samples
collected during a compliance period.
Coliforms are used as an indicator of
fecal contamination and to determine
the integrity of the water treatment
process and distribution system. Under
the TCR. no more than 5 percent of
distribution system samples collected in
any month may contain coliform
bacteria (no more than 1 sample per
month may be coliform positive in those
PWSs that collect fewer than 40 samples
per month). The number of samples to
be collected in a month is based on the
number of people served by the PWS.
3. Interim Enhanced Surface Water
Treatment Rule
The Interim Enhanced Surface Water
Treatment Rule (IESWTR) (63 FR 69478,
December 16, 1998) (USEPA 1998a)
applies to PWSs serving at least 10,000
people and using surface water or
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659
GWUDI sources. Key provisions
established by the IESWTR include the
following: (1) An MCLG of zero for
Cryptosporidium; (2) Cryptosporidium
removal requirements of 2-log (99
percent) for PWSs that filter; (3) more
stringent CFE turbidity performance
standards of 1.0 NTU as a maximum
and 0.3 NTU or less at the 95th
percentile monthly for treatment plants
using conventional treatment or direct
filtration; (4) requirements for
individual filter turbidity monitoring;
(5) disinfection benchmark provisions to
assess the level of microbial protection
that PWSs provide as they take steps to
comply with new DBF standards; (6)
inclusion of Cryptosporidium in the
definition of GWUDI and in the
watershed control requirements for
unfiltered PWSs; (7) requirements for
covers on new finished water storage
facilities; and (8) sanitary surveys for all
surface water systems regardless of size.
The IESWTR was developed in
conjunction with the Stage 1
Disinfectants and Disinfection
Byproducts Rule (Stage 1 DBPR) (63 FR
69389, December 16, 1998) (USEPA
1998b), which reduced allowable levels
of certain DBPs, including
trihalomethanes, haloacetic acids,
chlorite, and bromate.
4. Long Term 1 Enhanced Surface Water
Treatment Rule
The Long Term 1 Enhanced Surface
Water Treatment Rule ( LTlESWTR) (67
FR 1812, January 14, 2002) (USEPA
2002a) builds upon the microbial
control provisions established by the
IESWTR for large PWSs through"
extending similar requirements to small
PWSs. The LTlESWTR applies to PWSs
that use surface water or GWUDI as
sources and that serve fewer than 10,000
people. Like the IESWTR, the
LTlESWTR established the following: 2-
log (99 percent) Cryptosporidium
removal requirements by PWSs that
filter; individual filter turbidity
monitoring and more stringent
combined filter effluent turbidity
standards for conventional and direct
filtration plants: disinfection profiling
and benchmarking; inclusion of
Cryptosporidium in the definition of
GWUDI and in the watershed control
requirements for unfiltered PWSs; and
the requirement that new finished water
storage facilities be covered.
5. Filter Backwash Recycle Rule
The Filter Backwash Recycling Rule
(FBRR) (66 FR 31085, June 8, 2001)
(USEPA 2001a) requires PWSs to
consider the potential risks associated
with recycling contaminants removed
during the filtration process. The
provisions of the FBRR apply to all
PWSs that recycle, regardless of
population served. In general, the
provisions include the following: (1)
PWSs must return certain recycle
streams to a point in the treatment
process that is prior to primary
coagulant addition unless the State
specifies an alternative location; (2)
direct filtration PWSs recycling to the
treatment process must provide detailed
recycle treatment information to the
State; and (3) certain conventional
PWSs that practice direct recycling must
perform a one-month, one-time
recycling self assessment.
C. Concern With Cryptosporidium in
Drinking Water
1. Introduction
EPA is promulgating the LT2ESWTR
to reduce the public health risk
associated with Cryptosporidium in
drinking water. This section describes
the general basis for this public health
concern through reviewing information
in several areas: the nature of
Cryptosporidium, health effects, efficacy
of water treatment processes, and the
incidence of epidemic and endemic
disease. Further information about
Cryptosporidium is available in the
following documents: Cryptosporidium:
Human Health Criteria Document
(USEPA 2001b), Cryptosporidium:
Drinking Water Advisory (USEPA
2001c), and Cryptosporidium: Risks for
Infants and Children (USEPA 2001d).
2. What Is Cryptosporidium?
Cryptosporidium is a protozoan
parasite that lives and reproduces
entirely in one host. Ingestion of
Cryptosporidium can cause
cryptosporidiosis, a gastrointestinal (GI)
illness. Cryptosporidium is excreted in
feces. Transmission of cryptosporidiosis
occurs through consumption of water or
food contaminated with feces or by
direct or indirect contact with infected
persons or animals (Casemore 1990).
In the environment, Cryptosporidium
is present as a thick-walled oocyst
containing four organisms (sporozoites);
the oocyst wall insulates the sporozoites
from harsh environmental conditions.
Oocysts are 4-5 microns in length and
width. Upon a host's ingestion of
oocysts, enzymes and chemicals
produced by the host's digestive system
cause the oocyst to excyst, or break
open. The excysted sporozoites embed
themselves in the surfaces of the
epithelial cells of the lower small
intestine. The organisms then begin
absorbing nutrients from their host cells.
When these organisms sexually
reproduce, they produce thick- and
thin-walled oocysts. The host excretes
the thick-walled oocysts in its feces;
thin-walled oocysts excyst within the
host and contribute to further host
infection.
The exact mechanism by which
Cryptosporidium causes GI illness is not
known. Factors may include damage to
intestinal structure and cells, changes in
the absorption/secretion processes of
the intestine, toxins produced by
Cryptosporidium or the host, and
proteins that allow Cryptosporidium to
adhere to host cell surfaces (Carey et al.
2004).
Upon excretion, Cryptosporidium
oocysts may survive for months in
various environmental media, including
soil, river water, seawater, and human
and cattle feces at ambient temperatures
(Kato et al. 2001, Pokorny et al. 2002,
Payer et al. 1998a and 1998b, and
Robertson et al. 1992). Cryptosporidium
can also withstand temperatures as low
as — 20 °C for periods of a few hours
(Payer and Nerad 1996) but are
susceptible to desiccation (Robertson et
al. 1992).
Cryptosporidium is a widespread
contaminant in surface water used as
drinking water supplies. For example,
among 67 drinking water sources
surveyed by LeChevallier and Norton
(1995), 87 percent had positive samples
for Cryptosporidium. A more recent
survey of 80 medium and large PWSs
conducted by EPA detected
Cryptosporidium in 85 percent of water
sources (USEPA 2003a).
Cryptosporidium contamination can
come from animal agriculture,
wastewater treatment plant discharges,
slaughterhouses, birds, wild animals,
and other sources of fecal matter.
Because different species of
Cryptosporidium are very similar in
morphology, researchers have focused
on genetic differences in trying to
classify them. However, discussion on
Cryptosporidium taxonomy is
complicated by the fact that even within
species or strains, there may be
differences in infectivity and virulence.
Cryptosporidium parvum (C. parvum)
has been the primary species of concern
to humans. Until recently, some
researchers divided C. parvum into two
primary strains, genotype 1, which
infects humans, and genotype 2, which
infects both humans and cattle (Carey et
al. 2004). In 2002, Morgan-Ryan et al.
proposed that genotype 1 be designated
a separate species, C. hominis.
Additional Cryptosporidium species
infecting other mammals, birds, and
reptiles have been documented. In some
cases, these species can infect both
immunocompromised (having
weakened immune systems) and
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otherwise healthy humans (Carey et al.
2004).
3. Cryptosporidium Health Effects
Cryptosporidium infection is
characterized by mild to severe
diarrhea, dehydration, stomach cramps,
and/or a slight fever. Incubation is
thought to range from 2 to 10 days
(Arrowood 1997). Symptoms typically
last from several days to 2 weeks,
though in a small percentage of cases,
the symptoms may persist for months or
longer in otherwise healthy individuals.
Symptoms may be more severe in
immunocompromised persons (Frisby et
al. 1997, Carey et al. 2004). Such
persons include those with AIDS,
cancer patients undergoing
chemotherapy, organ transplant
recipients treated with drugs that
suppress the immune system, and
patients with autoimmune disorders
(e.g., Lupus). In AIDS patients,
Cryptosporidium has been found in the
lungs, ear, stomach, bile duct, and
pancreas in addition to the small
intestine (Farthing 2000).
Immunocompromised patients with
severe persistent cryptosporidiosis may
die (Carey et al. 2004). Besides the
immunocompromised, children and the
elderly may be at higher risk from
Cryptosporidium than the general
population (discussed in section VII.G).
Studies with human volunteers have
demonstrated that a low dose of C.
parvum (e.g., 10 oocysts) is sufficient to
cause infection in healthy adults,
although some strains are more
infectious than others (DuPont et al.
1995, Chappell et al. 1999, Okhuysen et
al. 2002). Studies of immunosuppressed
adult mice have demonstrated that a
single viable oocyst can induce C.
parvum infections (Yang et al. 2000,
Okhuysen et al. 2002). The lowest dose
tested in any of the human challenge
studies was 10 oocysts. Because
drinking water exposures are generally
projected to be at lower levels (e.g., 1
oocyst), statistical modeling is necessary
to project the effects of such exposure.
Following the advice of its Science
Advisory Board (SAB), EPA has
developed a range of models to predict
effects of exposure to low doses of
Cryptosporidium. These models are
discussed in section VI and in the
LT2ESWTR Economic Analysis (USEPA
2005a).
The degree and duration of the
immune response to Cryptosporidium is
not well characterized. In a study by
Chappell et al. (1999), volunteers with
IgG Cryptosporidium antibodies in their
blood were immune to low doses of
oocysts. The ID50 (the dose that infects
50 percent of the challenged population)
was 1,880 oocysts for those individuals
compared to 132 oocysts for individuals
that tested negativafor those antibodies.
However, earlier studies did not observe
a correlation between the development
of antibodies after Cryptosporidium
infection and subsequent protection
from illness (Okhuysen et al. 1998).
No cure for cryptosporidiosis is
known. Medical care usually involves
treatment for dehydration and nutrient
loss. Certain antimicrobial drugs like
Azithromycin, Paromomycin, and
nitazoxanide, the only drug approved
for cryptosporidiosis in children, have
been partially effective in treating
immunocompromised patients
(Rossignol et al. 1998). Therapies used
to treat retroviruses can be helpful in
fighting cryptosporidiosis in people
with AIDS and are more effective when
used in conjunction with antimicrobial
therapy. The effectiveness of
antiretroviral therapy is thought to be
related to the associated increase in
white blood cells rather than the
decrease in the amount of virus present.
4. Efficacy of Water Treatment Processes
on Cryptosporidium
EPA is particularly concerned about
Cryptosporidium because, unlike
pathogens such as bacteria and most
viruses, Cryptosporidium oocysts are
highly resistant to standard
disinfectants like chlorine and
c iloramines (Korich et al. 1990,
Ransome et al. 1993, Finch et al. 1997).
Consequently, control of
Cryptosporidium in most treatment
plants is dependent on physical removal
processes. However, due to their size
(4—5 microns), oocysts can sometimes
pass through filters.
Monitoring data on finished water
show that Cryptosporidium is
sometimes present in filtered, treated
drinking water (LeChevallier et al. 1991,
Aboytes et al. 2004). For example,
Aboytes et al. (2004) analyzed 1,690
finished water samples from 82 plants.
Of these, 22 plants had at least one
positive sample for infectious
Cryptosporidium (1.4 percent of all
samples were positive). All positive
samples occurred at plants that met
existing regulatory standards and many
had very low turbidity.
Waterborne outbreaks of
cryptosporidiosis have occurred even in
areas served by filtered surface water
supplies (Solo-Gabriele and Neumeister,
1996). In some cases, outbreaks were
attributed to treatment deficiencies, but
in others, the treatment provided by the
water system met the regulatory
requirements in place at that time.
These data indicate that even surface
water systems that filter and disinfect
can still be vulnerable to
Cryptosporidium, depending on the
source water quality and treatment
effectiveness.
Certain alternative disinfectants can
be more effective in treating for
Cryptosporidium. Both ozone and
chlorine dioxide have been shown to
inactivate Cryptosporidium, albeit at
doses much higher than those required
to inactivate Giardia, which has
typically been used to set disinfectant
doses (summarized in USEPA 2003a).
Studies have also demonstrated a
synergistic effect of treatment using
ozone followed by chlorine or
monochloramine (Rennecker et al. 2000,
Driedger et al. 2001). Significantly. UV
light has recently been shown to achieve
high levels of Cryptosporidium
inactivation at feasible doses
(summarized in USEPA 2003a).
Other processes that can help reduce
Cryptosporidium levels in finished
water include watershed management
programs, pretreatment processes like
bank filtration, and additional
clarification and filtration processes
during water treatment. Further,
optimizing treatment performance and
achieving very low levels of turbidity in
the finished water has been shown to
improve Cryptosporidium removal in
treatment plants (summarized in USEPA
2003a).
5. Epidemic: and Endemic Disease From
Cryptosporidium
Cryptosporidium has caused a
number of waterborne disease outbreaks
since 1984 when the first was reported
in the United States. Data from the
Centers for Disease Control and
Prevention (CDC) include ten outbreaks
caused by Cryptosporidium in drinking
water between 1984 and 2000, with
approximately 421,000 cases of illness
(CDC 1993, 1996, 1998, 2000, and 2002).
The most serious outbreak occurred in
1993 in Milwaukee; an estimated
403,000 people became sick (MacKenzie
et al. 1994), and at least 50
Cryptosporidium-associated deaths
occurred among the severely
immunocompromised (Hoxie et al.
1997). Further, a study by McDonald et
al. (2001) using blood samples from
Milwaukee children suggests that
Cryptosporidium infection was more
widespread than might be inferred from
the illness estimates by MacKenzie et al.
(1994).
The number of identified and
reported outbreaks in the CDC database
is believed to substantially understate
the actual incidence of waterborne
disease outbreaks and cases (Craun and
Calderon 1996, National Research
Council 1997). This under reporting is
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661
due to a number of factors. Many people
experiencing gastrointestinal illness do
not seek medical attention. Where
medical attention is provided, the
pathogenic agent may not be identified
through routine testing. Physicians and
patients often lack sufficient
information to attribute gastrointestinal
illness to any specific origin, such as
drinking water, and few States have an
active outbreak surveillance program. In
addition, if drinking water is
investigated as the source of an
outbreak, oocysts may not be detected in
water samples even if they are present,
due to limitations in analytical methods.
Consequently, outbreaks may not be
recognized in a community or, if
recognized, may not be traced to a
drinking water source.
In addition, an unknown but probably
significant portion of waterborne
disease is endemic (i.e., isolated cases
not associated with an outbreak) and,
thus, is even more difficult to recognize.
In an outbreak, if the pathogen has been
identified, medical providers and public
health investigators know what to look
for. In endemic disease, there is no
investigation, so the illness may never
be identified, or if it is, it may not be
linked to a source (e.g., drinking water,
person-to-person transmission). In
addition, where a pathogen is identified,
lab results may not be reported to public
health agencies.
Because of this under reporting, the
actual incidence of cryptosporidiosis
associated with drinking water is
unknown. However, indications of this
incidence rate can be roughly
extrapolated from different sources.
Mead et al. (1999) estimated
approximately 300,000 total cases of
cryptosporidiosis annually that result in
a physician visit, with 90 percent of
these attributed to waterborne (drinking
water and recreational water) and
secondary transmission. This estimate is
based on the percentage of stools that
test positive for Cryptosporidium and
applying this percentage to the
approximately 15 million physician
visits for diarrhea each year. While the
fraction of cryptosporidiosis cases that
result in a physician visit is unknown,
Corso et al. (2003) reported that during
the 1993 outbreak in Milwaukee,
medical care was sought in
approximately 12 percent of all
cryptosporidiosis cases.
Surveillance data from the CDC for
2001 show an overall incidence of 1.5
laboratory diagnosed cases of
cryptosporidiosis per 100,000
population (CDC, 2002). Although the
fraction of all cryptosporidiosis cases
that are laboratory confirmed is
unknown, during the 1993 Milwaukee
outbreak, 739 cases from an estimated
403,000 cases total were confirmed by a
laboratory (MacKenzie et al., 1994).
These data indicate a ratio of 1
laboratory confirmed case per 545
people estimated to be ill with
cryptosporidiosis.
A few studies have attempted to
determine exposure in certain areas by
measuring seroprevalence of
Cryptosporidium antibodies (the
frequency at which antibodies are found
in the blood). Detection of such
antibodies (seropositivity), however,
does not mean that the person actually
experienced symptoms of
cryptosporidiosis. An individual can be
asymptomatically infected and still
excrete oocysts. Seroprevalence, though,
is still a method for estimating the
exposure to Cryptosporidium that has
occurred within a limited time period
(the antibodies may last only a few
months).
Frost et al. (2001) conducted a paired
city study, in which the serological
response of blood donors in a city using
ground water as its water source was
compared to that of donors in a city
using surface water as its source. Rates
of seropositivity were higher (49 vs. 36
percent) in the city with the surface
water source. A similar study in two
other cities (Frost et al. 2002) showed a
seropositivity rate of 54 percent in the
city served by surface water compared
to 38 percent in the city served by
ground water. These studies suggest that
drinking water from surface sources
may be a factor in the higher rates of
seropositivity.
D. Specific Concerns Following the
IESWTR and LT1ESWTR
In the LT2ESWTR, EPA is addressing
a number of public health concerns that
remain following implementation of the
IESWTR and LT1ESWTR. These are as
follows:
• The need for filtered PWSs with
higher levels of source water
Cryptosporidium contamination to
provide additional risk-based treatment
for Cryptosporidium beyond IESWTR or
LT1ESWTR requirements;
• The need for unfiltered PWSs to
provide risk-based treatment for
Crvptosporidium to achieve equivalent
public health protection with filtered
PWSs; and
• The need for PWSs with uncovered
finished water storage facilities to take
steps to reduce the risk of
contamination of treated water prior to
distribution to consumers.
EPA and stakeholders identified each
of these issues as public health concerns
during development of the IESWTR
(USEPA 1994, 1997). However, the
Agency was unable to address these
concerns in those regulations due to
data gaps in the areas of health effects,
occurrence, analytical methods, and
treatment. Consequently, EPA followed
a two-stage strategy for microbial and
disinfection byproducts rules. Under
this strategy, the IESWTR and
LT1ESWTR were promulgated to
provide an initial improvement in
public health protection in large and
small PWSs, respectively, while
additional data to support a more
comprehensive regulatory approach
were collected.
Since promulgating the IESWTR and
LTlESWTR, EPA has worked with
stakeholders to collect and analyze
significant new information to fill data
gaps related to Cryptosporidium risk
management in PWSs. The next section
presents EPA's evaluation of these data
and their implications for both the risk
of Cryptosporidium in filtered and
unfiltered PWSs and the feasibility of
steps to limit this risk. In addition, the
Agency has evaluated additional data
related to mitigating risks with
uncovered finished water storage
facilities, which are presented in section
IV.F.
E. New Information on Cryptosporidium
Risk Management
EPA and stakeholders determined
during development of the IESWTR that
in order to establish risk-based
treatment requirements for
Cryptosporidium, additional
information was needed in the
following areas: (l) The risk associated
with a given level of Cryptosporidium
(i.e., inactivity); (2) the occurrence of
Cryptosporidium in PWS sources; (3)
analytical methods that would suffice
for making site-specific source water
Cryptosporidium density estimates; and
(4) the use of treatment technologies to
achieve specific levels of
Cryptosporidium disinfection (USEPA
1997).
In today's final LT2ESWTR, EPA is
promulgating risk-based
Cryptosporidium treatment
requirements for filtered and unfiltered
PWSs. The Agency believes that the
critical data gaps in the areas of
infectivity, occurrence, analytical
methods, and treatment that prevented
the adoption of such an approach under
earlier regulations have been addressed.
The new information that the Agency
and stakeholders evaluated in each of
these areas and its significance for
today's LT2ESWTR are summarized as
follows. See section VI.L for a summary
of public comments on EPA's use of
Cryptosporidium infectivity and
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occurrence data in assessing benefits of
the LT2ESWTR.
1. Infectivity
Infectivity relates the probability of
infection to the number of
Cryptosporidium oocysts that a person
ingests. It is used to predict the disease
burden associated with a particular
Cryptosporidium level in drinking
water. Information on Cryptosporidium
infectivity comes from dose-response
studies where healthy human
volunteers ingest different numbers of
oocysts (i.e., the "dose") and are
subsequently evaluated for signs of
infection and illness (i.e., the
"response").
Prior to the IESWTR, data from a
human dose-response study of one
Cryptosporidium isolate (IOWA) had
been published (DuPont et al. 1995).
Following IESWTR promulgation, a
study of two additional isolates (TAMU
and tlCP) was completed and published
(Okhuysen et al. 1999). This 1999 study
also reanalyzed the IOWA study results.
The measured infectivity of
Cryptosporidium oocysts varied over a
wide range in the Okhuysen et al. (1999)
study. The UCP oocysts were much less
infective than the IOWA oocysts, and
the TAMU oocysts were much more
infective.
EPA analyzed these new data for the
proposed LT 2ESWTR using two
different dose-response models. This
analysis suggested that the overall
infectivity of Cryptosporidium is greater
than was estimated for the IESWTR
(USEPA 2003a). Specifically, EPA
estimated the mean probability of
infection from ingesting a single
infectious oocyst ranges from 7 to 10
percent. This infection rate is
approximately 20 times higher than the
estimate of 0.4 percent used in the
IESWTR.
Since the publication of the proposed
LT2ESWTR, EPA has evaluated three
additional studies of Cryptosporidium
infectivity. EPA also received a
recommendation from the SAB that it
analyze Cryptosporidium infectivity
data using a wider range of models.
Accordingly, EPA re-estimated
Cryptosporidium infectivity using the
new data and six different dose-
response models, including the two
models used at proposal. Estimates from
the new data and models for the
probability of infection from ingesting a
single infectious oocyst range from 4 to
16 percent. A detailed discussion of the
models and their varying assumptions is
provided in the LT2ESWTR Economic
Analysis (USEPA 2005a).
As is apparent from these results,
substantial uncertainty about the
infectivity of Cryptosporidium remains
in several areas. These include the
variability in host susceptibility,
response at very low oocyst doses
typical of drinking water ingestion, and
the relative infectivity and occurrence of
different Cryptosporidium isolates in
the environment. To address this
uncertainty, EPA conducted its health
risk reduction and benefits analyses
using a representative range of model
results. In the summary tables for these
analyses, three sets of estimates are
presented: A "high" estimate based on
the model that showed the highest mean
baseline risk; a "medium" estimate,
based on the models and data used at
proposal, which also happens to be in
the middle of the range of estimates
produced by the six models using the
newly available data; and a "low"
estimate, based on the model that
showed the lowest mean baseline risk.
These estimates should not be
construed as upper and lower bounds
on illnesses avoided and benefits. For
each model, a distribution of effects is
estimated, and the "high" and "low"
estimates show only the means of these
distributions for two different model
choices. The detailed distribution of
effects is presented for the proposal
model in the Economic Analysis
(USEPA 2005a). Further, the "six dose-
response models used in this analysis
do not cover all possible variations of
models that might have been used with
the data, and it is possible that estimates
with other models would fall outside
the range presented. However, as
discussed in the Economic Analysis,
EPA believes that the models used in
the analyses reflect a reasonable range of
results based on important dimensions
of model choice.
Regardless of which model is chosen,
the available infectivity data suggest
that the risk associated" with a given
concentration of Cryptosporidium is
most likely higher than EPA had
estimated for the IESWTR. This finding
supports the need for increased
treatment for Cryptosporidium as
required under the LT2ESWTR.
2. Occurrence
Information on the occurrence of
Cryptosporidium oocysts in drinking
water sources is a critical parameter for
assessing risk and the need for
additional treatment for this pathogen.
For the IESWTR, EPA had no national
survey data on Cryptosporidium
occurrence and relied instead on several
studies that were local or regional. After
promulgating the IESWTR, EPA
obtained data from two national
surveys, the Information Collection Rule
(ICR) and the ICR Supplemental Surveys
(ICRSS), which were designed to
provide improved estimates of
occurrence on a national basis.
The ICR included monthly sampling
for Cryptosporidium and other water
quality parameters from the sources of
approximately 350 large PWSs over 18
months. The ICRSS involved twice-per-
month Cryptosporidium sampling from
the sources of a statistically random
sample of 40 large and 40 medium
PWSs over 12 months. In addition, the
ICRSS required the use of an improved
analytical method for Cryptosporidium
analysis that had a higher method
recovery (the likelihood that an oocyst
present in the sample will be counted)
and enhanced sample preparation
procedures.
EPA analyzed ICR and ICRSS data
using a statistical model to account for
factors like method recovery and sample
volume analyzed. As described in more
detail in EPA's Occurrence and
Exposure Assessment for the
LT2ESWTR (USEPA 2005b), the ICR
and ICRSS results demonstrate two
main differences for filtered PWSs in
comparison to Cryptosporidium
occurrence data used for the IESWTR:
(1) The occurrence of Crvptosporidium in
many drinking water sources is lower than
was indicated by the data used in IESWTR.
For example, median Cryptosporidium levels
for the ICR and ICRSS data are approximately
0.05/L. which is nearly 50 times lower than
the median IESWTR estimates of 2.3 oocysts/
MUSEPA 1998a).
(2) Cryptosporidium occurrence is more
variable from location to location than was
shown by the data considered for the
IESWTR. This finding demonstrates that.
although median occurrence levels are below
those estimated for the IESWTR, a subset of
PWSs contains Cryptosporidium levels that
are considerably greater than the median.
These results, therefore, indicate that
Cryptosporidium levels are relatively
low in most water sources, but a subset
of sources with relatively higher
concentrations may require additional
treatment. These findings support a risk-
targeted approach for the LT2ESWTR
wherein additional Cryptosporidium
treatment is required only for filtered
PWSs with the highest source water
pathogen levels.
Only the ICR provided data to
evaluate Cryptosporidium occurrence in
unfiltered PWS sources. The median
Cryptosporidium level among unfiltered
PWS sources was 0.0079 oocysts/L. This
level is approximately 10 times lower
than the median level for filtered PWS
sources.
When the Cryptosporidium removal
that filtered PWSs achieve is taken into
account, these occurrence data suggest
that unfiltered PWSs typically have
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663
higher concentrations of
Cryptosporidium in their treated water
than filtered PWSs. EPA has estimated
that on average, conventional filtration
plants remove around 99.9 percent (3-
log) of the Cryptosporidium present in
the source water. Most unfiltered PWSs,
however, provide no treatment for
Cryptosporidium. If an unfiltered PWS
had a source water Cryptosporidium
level 10 times lower than a filtered PWS
and the filtered PWS achieved 3-log
Cryptosporidium removal, then the
Cryptosporidium level in the treated
water of the unfiltered PWS would be
100 times higher than in the filtered
PWS.
These results suggest that to achieve
public health protection equivalent to
that provided by filtered PWSs,
unfiltered PWSs must take additional
steps. Thus, this finding supports the
need for Cryptosporidium treatment
requirements for unfiltered PWSs under
the LT2ESWTR.
3. Analytical Methods
To establish risk-targeted treatment
requirements, analytical methods must
be available to estimate the contaminant
densities in PWS sources. These density
estimates are used to determine the
level of treatment that is needed at a
particular site.
When EPA developed the IESWTR,
the best available method for measuring
Cryptosporidium was the Information
Collection Rule Protozoan Method (ICR
Method). The ICR Method provided a
quantitative measurement of
Cryptosporidium oocysts, but typically
undercounted the actual occurrence due
to low method recovery. For example, in
a spiking study (studies in which
known quantities of oocysts are added
to water samples) conducted during the
ICR survey, the mean recovery of spiked
Cryptosporidium oocysts was only 12
percent (Scheller et al. 2002). EPA
concluded that the ICR Method was
adequate for making national
occurrence estimates in the ICR survey
but would not suffice for making
estimates of Cryptosporidium levels at
specific sites.
Subsequent to promulgating the
IESWTR, EPA developed an improved
Cryptosporidium method, EPA Method
1622 (and later, 1623), to achieve higher
recovery rates and lower inter- and
intra-laboratory variability than
previous methods. Methods 1622 and
1623 incorporate improvements in the
concentration, separation, staining, and
microscope examination procedures.
During the ICRSS, which required the
use of Method 1622 or 1623, a spiking
study demonstrated a mean
Cryptosporidium recovery of 43 percent
(Connell et al. 2000). Thus, mean
Cryptosporidium recovery with
Methods 1622 and 1623 was more than
3.5 times higher compared to the ICR
Method performance in the earlier
spiking study. In addition, the relative
variation in recovery from sample to
sample was lower with Methods 1622
and 1623.
As described in section IV of this
preamble, EPA has concluded that a
monitoring program using Methods
1622 or 1623 can be effective in
characterizing PWSs source water
Cryptosporidium levels for purposes of
determining the need for additional
treatment requirements. This finding
supports the feasibility of risk-targeted
treatment requirements under the
LT2ESWTR.
4. Treatment
To establish risk-targeted
Cryptosporidium treatment
requirements, feasible treatment
processes must be available that allow
PWSs to inactivate or remove
Cryptosporidium. PWSs may then
implement these treatment processes to
comply with additional treatment
requirements.
During development of the IESWTR,
EPA recognized that chlorine, the most
commonly used disinfectant, is
ineffective for inactivating
Cryptosporidium. Studies suggested that
other disinfectants like ozone and
chlorine dioxide could be effective
against Cryptosporidium. However, EPA
concluded that data available at that
time were not sufficient to define how
any disinfectant could be applied to
achieve a specific level of
Cryptosporidium inactivation (USEPA
1997). This conclusion was due in part
to methodological inconsistencies and
shortcomings in the available studies.
With the completion of major studies
since promulgation of the IESWTR, EPA
has acquired the data necessary to
establish standards for Cryptosporidium
inactivation by several disinfectants. For
ozone and chlorine dioxide, EPA
reviewed new studies by Rennecker et
al. (1999), Owens et al. (1999, 2000),
Oppenheimer et al. (2000), Ruffell et al.
(2000), and Li et al. (2001). Collectively,
these studies cover a wide range of both
natural and laboratory water conditions.
Based on these studies, EPA has
developed tables that specify the
product of ozone or chlorine dioxide
concentration and time of exposure (i.e.,
CT tables) needed to achieve up to 3-log
Cryptosporidium inactivation. Section
IV.D of this preamble shows these
tables.
Most significantly, many recent
studies have demonstrated that UV light
is efficient for inactivating high levels of
Cryptosporidium. These studies include
Clancy et al. (1998, 2000, 2002), Bukhari
et al. (1999), Craik et al. (2000, 2001),
Landis et al. 2000), Sommer et al.
(2001), Shin et al. (2001), and
Oppenheimer et al. (2002). Using results
from these studies, EPA has defined the
UV light intensity and exposure time
required for up to 4-log
Cryptosporidium inactivation. Section
IV.D presents these values. EPA has
determined that UV light is a feasible
technology for PWSs of all sizes to
inactivate Cryptosporidium.
EPA has also developed standards for
processes that physically remove
Cryptosporidium contamination. These
processes include river bank filtration,
sedimentation basins, bag filters,
cartridge filters, and membranes.
Section IV.D presents design and
operational standards for these
processes, along with a summary of
supporting studies.
The development of these standards
for Cryptosporidium inactivation and
removal processes overcomes a
significant limitation that existed when
EPA developed the IESWTR. These
standards will allow PWSs to
implement cost-effective strategies to
comply with additional
Cryptosporidium treatment
requirements under the LT2ESWTR.
F. Federal Advisory Committee
Recommendations
EPA convened the Stage 2 M-DBP
Federal Advisory Committee in March
1999 to evaluate new information and
develop recommendations for the
LT2ESWTR and Stage 2 DBPR. The
Committee was comprised of
representatives from EPA, State and
local public health and regulatory
agencies, local elected officials, Indian
Tribes, drinking water suppliers,
chemical and equipment manufacturers,
and public interest groups. A technical
workgroup provided analytical support
for the Committee's discussions.
Committee members signed an
Agreement in Principle in September
2000 stating consensus
recommendations of the group. The
Agreement was published in a
December 29, 2000 Federal Register
notice (USEPA 2000a). For the
LT2ESWTR, the consensus
recommendations of the Committee are
summarized as follows:
(1) Supplemental risk-targeted
Cryptosporidium treatment by filtered
PWSs with higher source water
contaminant levels as shown by
monitoring results;
(2) Cryptosporidium inactivation by
all unfiltered PWSs, which must meet
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overall treatment requirements using a
minimum of 2 disinfectants;
(3) A "toolbox" of treatment and
control processes for PWSs to comply
with Cryptosporidium treatment
requirements;
(4) Reduced monitoring burden for
small filtered PWSs;
(5) Future monitoring to confirm or
revise source water quality assessments;
(6) Development of guidance for UV
disinfection and other toolbox
components; and
(7) Cover or treat existing uncovered
finished water reservoirs (i.e., storage
facilities) or implement risk mitigation
plans.
These recommendations reflect a
Committee judgement that, based on
available information, additional risk-
based Cryptosporidium treatment
requirements for filtered and unfiltered
PWSs are appropriate and feasible
under the LT2ESWTR. Much of today's
final LT2ESWTR reflects the
Committee's recommendations. The
next part of this preamble describes
specific requirements of the rule.
IV. Explanation of Today's Action
A. Source Water Monitoring
Requirements
Today's rule requires PWSs using
surface water or GWUDI sources to
monitor their source water to assess the
level of Cryptosporidium. Monitoring
results assign a PWS to a
Cryptosporidium treatment bin, which
determines the extent of additional
Cryptosporidium treatment
requirements (sections IV.B and IV.C
described treatment requirements for
filtered and unfiltered PWSs,
respectively).
Source water monitoring under the
LT2ESWTR is designed to ascertain the
mean level of Cryptosporidium in the
influent to a surface water treatment
plant. Requirements differ by PWS size
(above or below 10,000 people served)
and treatment plant type (filtered or
unfiltered PWS). This section describes
monitoring requirements for sampling
parameters and frequency, sampling
location, sampling schedule, monitoring
plants that operate only part of the year,
failing to monitor, providing treatment
instead of monitoring, grandfathering
previously collected data, ongoing
watershed assessment, second round of
monitoring, and new source monitoring.
Other sections of this preamble
describe additional requirements related
to monitoring, including compliance
schedules (section IV.G), reporting of
monitoring results (section IV.I), use of
approved analytical methods, including
minimum sample volume (section IV.J),
and use of approved laboratories
(section IV.K). As described in section
IV.G, monitoring compliance dates
under the LT2ESWTR are staggered:
smaller PWSs begin monitoring after
larger PWSs.
For additional information, see
Source Water Monitoring Guidance
Manual for Public Water Systems under
the Long Term 2 Enhanced Surface
Water Treatment Rule. This document
provides guidance on sampling location,
procedures for collecting and shipping
samples, contracting with laboratories,
and related topics to assist PWSs in
complying with LT2ESWTR monitoring
requirements. It may be acquired from
EPA's Safe Drinking Water Hotline,
which can be contacted as described
under FOR FURTHER INFORMATION
CONTACT at the beginning of this
document.
1. Today's Rule
a. Sampling parameters and
frequency. Requirements for the source
water parameters that PWSs must
measure under the LT2ESWTR, as well
as the sampling frequency and duration,
are stated as follows for large and small
PWSs, including both filtered and
unfiltered plants:
Large Filtered PWSs
Filtered PWSs serving at least 10,000
people must sample at least monthly for
Cryptosporidium, E. coli, and turbidity
for a period of two years. Sampling may
be conducted at a higher frequency (e.g.,
twice-per-month, once-per-week) but
the sampling must be evenly spaced
throughout the monitoring period. As
described in section IV.B, filtered PWSs
that sample at least twice-per-month
over two years use a different
calculation, which is less conservative,
to determine their treatment bin
classification under the LT2ESWTR.
Large Unfiltered PWSs
Unfiltered PWSs serving at least
10,000 people must also sample for
Cryptosporidium at least monthly for a
period of 2 years. No E. coli or turbidity
monitoring is required for unfiltered
PWSs. Unfiltered PWSs may choose to
sample more frequently; however, as
described in section IV.C, a higher
sampling frequency does not change the
calculation used to determine unfiltered
PWS Cryptosporidium treatment
requirements.
Small Filtered PWSs
Filtered PWSs serving fewer than
10,000 people (i.e., small PWSs)
monitor under the LT2ESWTR using a
two-phase strategy that begins with an
indicator screening analysis. Small
filtered PWSs must initially sample for
E. coli at least once every two weeks for
a period of one year. Cryptosporidium
monitoring is required of these PWSs
only if the indicator monitoring results
meet one of the following conditions:
(1) For PWSs using lake/reservoir
sources, the annual mean E. coli
concentration is greater than 10 E. coli/
100 mL.
(2) For PWSs using flowing stream
sources, the annual mean E. coli
concentration is greater than 50 E. coli/
100 mL.
PWSs using ground water under the
direct influence of surface water must
comply with the requirement to monitor
for Cryptosporidium based on the E. coli
level that applies to the nearest surface
water body. If no surface water body is
nearby, the PWS must comply based on
the requirements that apply to PWSs
using lake/reservoir sources.
The State may approve small filtered
PWSs to monitor for an indicator other
than E. coli. The State also may approve
an alternative E. coli concentration to
trigger Cryptosporidium monitoring.
This approval must be in writing and
must be based on a State determination
that the alternative indicator and/or
trigger level will more accurately
identify whether a PWS will exceed the
Bin 1 Cryptosporidium level of 0.075
oocysts/L, as stated in section IV.B.I of
this preamble. EPA will issue guidance
to States on alternative indicators and
trigger levels, if warranted, based on
large PWS monitoring results.
Small filtered PWSs may elect to skip
E. coli monitoring if they notify the
State that they will monitor for
Cryptosporidium. PWSs must notify the
State no later than three months prior to
the date the PWS is required to begin
monitoring (see section IV.G for specific
dates).
Small filtered PWSs that are required
to monitor for Cryptosporidium must
conduct this monitoring using either of
two frequencies: (1) Sample at least
twice-per-month for a period of one year
or (2) sample at least once-per-month lor
a period of two years. Note that the
same treatment compliance dates apply
to the PWS regardless of which
Cryptosporidium sampling frequency is
used (i.e., selecting the two-year
Cryptosporidium sampling frequency
does not extend Cryptosporidium
treatment compliance deadlines).
Small Unfiltered PWSs
All unfiltered PWSs serving fewer
than 10,000 people must monitor for
Cryptosporidium. The E. coli screening
analysis used by small filtered PWSs is
not applicable to small unfiltered PWSs.
Small unfiltered PWSs must use either
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665
of the same two Cryptosporidium
sampling frequencies available to small
filtered PWSs: (1) Sample twice-per-
month for one year or (2) sample once-
per-month for two years. As with small
filtered PWSs, the same treatment
compliance dates apply to the PWS
regardless of which Cryptosporidium
sampling frequency is used.
b. Sampling location. PWSs must
collect source water samples for each
plant that treats a surface water or
GWUDI source. However, where
multiple plants receive all of their water
from the same influent, such as plants
that draw water from the same intake or
pipe, the State may approve one set of
monitoring results to be applied to all
plants.
PWSs must collect source water
samples prior to chemical treatment,
such as coagulants, oxidants, and
disinfectants, unless the following
condition is met: The State may approve
a system to collect a sample after
chemical treatment if the State
determines that collecting a sample
prior to chemical-treatment is not
feasible and that the chemical treatment
is unlikely to have a significant adverse
effect on the analysis of the sample.
PWSs that recycle filter backwash must
collect samples prior to the point of
filter backwash addition due to the
likely presence of coagulant and other
treatment chemicals in the backwash.
See section IV.D.6 for directions on
sampling location for PWSs using bank
filtration.
For plants that use multiple water
sources at the same time, PWSs must
collect samples from a tap where the
sources are combined prior to treatment,
if available. If a blended source tap is
not available, PWSs must collect
samples from each source and either
analyze a weighted composite (blended)
sample or analyze samples from each
source separately and determine a
weighted average of the results. The
weighting of sources must reflect the
relative usage of the different sources by
the treatment plant at the time the
sample is collected.
PWSs must submit a description of
their proposed sampling location(s) to
the State no later than three months
prior to the date the PWS must begin
monitoring (see section IV.G for specific
dates). This description must address
the position of the sampling location in
relation to the PWS's water source(s)
and treatment processes, including
points of chemical addition and filter
backwash recycle. If the State does not
respond to a PWS regarding sampling
location(s), the PWS must begin
sampling at the reported location. See
Source Water Monitoring Guidance
Manual for Public Water Systems under
the Long Term 2 Enhanced Surface
Water Treatment Rule, which can be
acquired as stated previously, for
guidance on sampling location
descriptions.
c. Sampling schedule. PWSs must
collect samples in accordance with a
schedule that the PWS develops and
reports prior to initiating monitoring.
The sampling schedule must specify the
calendar dates when the PWS will
collect each required sample in a
particular round of monitoring.
Scheduled sampling dates must be
evenly distributed throughout the
monitoring period, but may be arranged
to accommodate holidays, weekends,
and other events when collecting or
analyzing a sample would be
problematic (e.g., a PWS is not required
to schedule samples on the same
calendar date each month).
PWSs must submit sampling
schedules no later than three months
prior to the date the PWS must begin a
round of monitoring (see section IV.G
for specific dates). Unless the State
approves an alternative procedure, large
PWSs (serving at least 10,000 people)
must report their sampling schedule for
initial source water monitoring to EPA
using the LT2ESWTR electronic data
reporting and review system described
in section IV.I. Schedules for initial
monitoring by small PWSs and for the
second round of monitoring by all PWSs
must be reported to the State. PWSs
should verify that their laboratory can
accommodate the scheduled sampling
dates before submitting the schedule.
EPA will not formally approve
sampling schedules but will notify a
PWS if its sampling schedules does not
meet the requirements of today's rule
(e.g., does not include the required
number of samples). If a PWS does not
receive notification from the State or
EPA regarding the sampling schedule,
the PWS must begin monitoring
according to the reported sampling
schedule.
PWSs must collect samples within
two days before or two days after the
dates indicated in their sampling
schedules {i.e., within a 5-day period
around the schedule date) unless one of
the following two conditions applies:
(1) If an extreme condition or
situation exists that may pose danger to
the sample collector, or that cannot be
avoided and causes the PWS to be
unable to sample in the scheduled 5-day
period, the PWS must sample as close
to the scheduled date as is feasible
unless the State approves an alternative
sampling date. The PWS must submit an
explanation for the delayed sampling
date to the State concurrent with the
shipment of the samples to the
laboratory.
(2) If a PWS is unable to report a valid
analytical result for a scheduled
sampling date due to equipment failure,
loss of or damage to the sample, failure
to comply with the analytical method
requirements, or the failure of an
approved laboratory to analyze the
sample, then the PWS must collect a
replacement sample. Collection of the
replacement sample must occur within
21 days of the PWS receiving
information that an analytical result
cannot be reported for the scheduled
date unless the PWS demonstrates that
collecting a replacement sample within
this time frame is not feasible or the
State approves an alternative resampling
date. The PWS must submit an
explanation for the resampling date to
the State concurrent with the shipment
of the sample to the laboratory.
Failure to collect a required sample
within the 5-day period around a
scheduled date that does not meet one
of these two conditions is a monitoring
violation. PWSs must revise their
sampling schedules to add dates for
collecting all missed samples and must
submit the revised schedule to the State
for approval prior to when the PWS
begins collecting the missed samples.
d. Plants operating only part of the
year. Some PWSs operate surface water
treatment plants for only part of the
year. This includes PWSs that provide
water for only a fraction of the year (e.g.,
resorts open only in the summer) and
PWSs that use a surface water plant to
supplement another source only during
periods of high demand.
Most LT2ESWTR monitoring,
treatment, and implementation schedule
requirements apply to such plants.
Monitoring requirements, however,
differ in two respects:
(!) PWSs must conduct sampling only
during months of the 2 year monitoring
period when the plant operates unless
the State specifies another monitoring
period based on plant operating
practices; and
(2) For plants that operate less than
six months per year and where
Cryptosporidium monitoring is
required, PWSs must collect at least six
Cryptosporidium samples per year
during each of two years of monitoring.
e. Failing to monitor. Today's rule
requires PWSs to provide a Tier 3 public
notice for violation of monitoring and
testing procedure requirements,
including the failure to collect one or
two source water Cryptosporidium
samples. If a PWS fails to collect three
or more Cryptosporidium samples, other
than in specifically exempted situations
(see section IV.A.l.c), the PWS must
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provide a Tier 2 special public notice.
Violations for failing to monitor persist
until the State determines that the PWS
has begun sampling on a revised
schedule that includes dates for the
collection of missed samples. Section
IV.H provides further details on public
notice requirements of the LT2ESWTR.
PWSs must report their bin
classification (or mean Cryptosporidium
level for unfiltered PWSs) no later than
six months after the end of the
scheduled monitoring period (specific
dates in section IV.G). Failure by a PWS
to collect the required number of
Cryptosporidium samples to report its
bin classification or mean
Cryptosporidium level by the
compliance date is a treatment
technique violation and the PWS must
provide a Tier 2 special public notice
(unless the PWS has already provided a
Tier 2 public notice for missing three
sampling dates and is successfully
meeting a State-approved schedule for
sampling). The treatment technique
violation and public notice
requirements persist until the State
determines that the PWS is
implementing a State-approved
monitoring plan to allow bin
classification or will install the highest
level of treatment required under the
rule, as described next.
f. Providing treatment instead of
monitoring. PWSs are not required to
conduct source water monitoring under
the LT2ESWTR for plants that will
provide the highest level of treatment
required under the rule. This applies
both to plants that provide this level of
treatment at the time the plant would
otherwise begin source water
monitoring and to plants that commit to
install technology to achieve this level
of treatment by the applicable
compliance date for meeting
Cryptosporidium treatment
requirements under the LT2ESWTR.
Filtered PWSs are not required to
monitor at plants that will provide a
total of at least 5.5-log of treatment for
Cryptosporidium, equivalent to meeting
the treatment requirements of Bin 4 as
discussed in section IV.B. Unfiltered
PWSs are not required to monitor for
plants that will provide a total of at least
3-log of Cryptosporidium inactivation,
equivalent to meeting the treatment
requirements for unfiltered PWSs with
source water Cryptosporidium levels
above 0.01 oocysts/L as discussed in
section IV.C.
PWSs that intend to provide this level
of treatment rather than initiate
monitoring must notify the State no
later than three months prior to the
month the PWS must otherwise begin
monitoring. PWSs submit this
notification in lieu of submitting a
sampling schedule. In addition, a PWS
may choose to stop sampling at any
point after it has initiated monitoring if
it notifies the State that it will provide
the highest level of treatment. In both
cases, the PWSs must install and
operate technologies to achieve this
level of treatment no later than the
applicable Cryptosporidium treatment
compliance date for the PWS as
specified in section IV.G. Failure to
provide this treatment by the
compliance date is a treatment
technique violation.
g. Grandfathering previously collected
data. If the State approves, PWSs may
comply with the initial source water
monitoring requirements of today's rule
by using (i.e., grandfathering) sample
results collected before the PWS is
required to begin monitoring. PWSs may
grandfather monitoring results either in
lieu of or in addition to conducting new
monitoring under the rule. To be
eligible for grandfathering, monitoring
results must be equivalent in data
quality to monitoring PWSs conduct
under today's rule and the PWS must
comply with reporting requirements.
Details of these requirements follow.
Grandfathered Data Quality
Requirements
• Analysis of E. coli samples must
meet the analytical method and
approved laboratory requirements for
source water monitoring under today's
rule. PWSs are not required to report E.
coli and turbidity data in order to
grandfather Cryptosporidium
monitoring results, although EPA
requests that PWSs report these data if
they are available. PWSs that
grandfather Cryptosporidium data
without associated E. coli and turbidity
data are not required to conduct
separate monitoring for these
parameters when they have satisfied
Cryptosporidium monitoring
requirements.
• Analysis of Cryptosporidium
samples must meet the criteria of a
validated version of EPA Method 1622
or 1623, which are described in USEPA
1999a, USEPA 1999b, USEPA 2001e,
USEPA 2001f, USEPA 2005c, and
USEPA 2005d. The volume analyzed for
each sample must meet the criteria
described in section IV.J, which are at
least 10 L of sample or at least 2 mL of
packet pellet volume or as much volume
as two approved filters can
accommodate before clogging.
• The sampling location must meet
the criteria for LT2ESWTR monitoring,
as described previously.
• For Cryptosporidium samples, the
sampling frequency must be at least
monthly and on a regular schedule. The
collection of individual samples may
deviate from a regular schedule under
the same criteria that apply to deviation
from LT2ESWTR sampling schedules, as
described previously. Additionally,
deviations in the sampling frequency of
previously collected data are allowed
under the following conditions: (1)
PWSs may grandfather data where there
are gaps in the sampling frequency if the
State approves and if the PWS conducts
additional monitoring when specified
by the State to ensure the data used for
bin classification are seasonally
representative and unbiased; and (2)
PWSs may grandfather data where the
sampling frequency varies (e.g., one year
of sampling monthly and one year of
sampling twice-per-month); monthly
average sample concentrations must be
used to calculate the bin classification,
as described in section IV.B.
Grandfathered Data Reporting
Requirements
PWSs that request to grandfather
previously collected monitoring results
must report the following information
by the applicable dates listed in this
section. PWSs serving at least 10,000
people must report this information to
EPA unless the State approves an
alternate procedure for reporting. PWSs
serving fewer than 10,000 people must
report this information to the State,
PWSs must report that they intend to
submit previously collected monitoring
results for grandfathering. This report
must specify the number of previously
collected results the PWS will submit,
the dates of the first and last sample,
and whether a PWS will conduct
additional source water monitoring for
initial bin classification. PWSs must
report this information no later than
three months prior to the date the PWSs
is required to start monitoring, as shown
in section IV.G.
PWSs must report previously
collected monitoring results for
grandfathering, along with the required
documentation listed in this section, no
later than two months after the month
the PWS is required to start monitoring,
as shown in section IV.G.
• For each sample Cryptosporidium
or E. coli result, PWSs must report the
applicable data elements in section
IV.I.l.
• PWSs must certify to EPA or the
State that the reported monitoring
results include all results the PWS
generated during the time period
beginning with the first reported result
and ending with the final reported
result. This applies to samples that were
collected from the sampling location
specified for source water monitoring
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under this subpart, not spiked, and
analyzed using the laboratory's routine
process for the analytical methods listed
in this section.
• PWSs must certify to EPA or the
State that the samples were
representative of a plant's source
water(s) and the source water(s) have
not changed. PWSs must submit to EPA
a description of the sampling location(s)
for each water treatment plant, which
must address the position of the
sampling location in relation to the
PWS's water source(s) and treatment
processes, including points of chemical
addition and filter backwash recycle.
• For Cryptosporidium samples, the
laboratory or laboratories that analyzed
the samples must provide a letter
certifying that the quality control
criteria specified in the methods listed
in this section were met for each sample
batch associated with the reported
results. Alternatively, the laboratory
may provide bench sheets and sample
examination report forms for each field,
matrix spike, initial precision and
recovery (IPR), ongoing precision and
recovery (OPR), and method blank
sample associated with the reported
results.
• If the State determines that a
previously collected data set submitted
for grandfathering was generated during
source water conditions that were not
normal for the PWS, such as a drought,
the State may disapprove the data.
Alternatively, the State may approve the
previously collected data if the PWS
reports additional source water
monitoring data, as determined by the
State, to ensure that the overall data set
used for bin classification represents
average source water conditions for the
PWS.
If a PWS submits previously collected
data that fully meet the number of
samples required for initial source water
monitoring and some of the data are
rejected due to not meeting the
requirements of this section, PWSs must
conduct additional monitoring to
replace rejected data on a schedule the
State approves. PWSs are not required
to begin this additional monitoring until
at least two months after notification
that data have been rejected and
additional monitoring is necessary.
h. Ongoing watershed assessment.
Today's rule includes provisions to
assess changes in a PWS's source water
quality following initial bin
classification. As required by 40 CFR
142.16(b)(3)(i), source water is one of
the components that States must
address during the sanitary surveys that
are required for surface water PWSs.
These sanitary surveys must be
conducted every 3 years for community
PWSs and every 5 years for non-
community PWSs. Under today's rule, if
the State determines during the sanitary
survey or an equivalent source water
assessment that significant changes have
occurred in the watershed that could
lead to increased contamination of the
source water by Cryptosporidium, the
PWS must take actions specified by the
State to address the contamination.
These actions may include additional
source water monitoring and/or
implementing options from the
microbial toolbox discussed in section
IV.D.
i. Second round of monitoring. PWSs
must begin a second round of source
water monitoring beginning six years
after initial bin classification (see
compliance dates in section IV.G). If
EPA does not modify LT2ESWTR
requirements by issuing a new
regulation prior to the second round of
monitoring, PWSs must carry out this
monitoring according to the
requirements that apply to the initial
round of source water monitoring. PWSs
will then be reclassified in LT2ESWTR
treatment bins based on the second-
round monitoring result. However, if
EPA changes the LT2ESWTR treatment
bin structure to reflect a new analytical
method or new risk information, PWSs
will undergo a risk characterization in
accordance with the revised rule.
j. New source monitoring. A PWS that
begins using a new surface water source
after the date the PWS is required to
conduct source water monitoring under
the LT2ESWTR must monitor the new
source on a schedule approved by the
State. This applies to both new plants
that begin operation and previously
operating plants that bring a new source
on-line after the required monitoring
date for the PWS. The State may
determine that monitoring should be
conducted before a new plant or source
is brought on-line or initiated within
some time period afterward. The new
source monitoring must meet all
LT2ESWTR requirements as specified
previously in this section. The PWS
must also determine its treatment bin
classification and comply with any
additional Cryptosporidium treatment
requirements based on the monitoring
results on a schedule approved by the
State.
2. Background and Analysis
Monitoring requirements in today's
rule are designed to ascertain
Cryptosporidium levels with suitable
accuracy for making treatment bin
classifications and in a time frame that
does not delay the installation of
Cryptosporidium treatment where
needed. The following discussion
summarizes the basis for monitoring
requirements with respect to sampling
parameters and frequency, sampling
location, sampling schedule, monitoring
plants that operate for only part of the
year, failing to monitor, grandfathering
previously collected data, ongoing
watershed assessment, and the second
round of monitoring. Most of these
requirements were part of the August
11. 2003, proposal for today's final rule,
and supporting analyses are presented
in greater detail in the proposal (USEPA
2003a). Differences from proposed
requirements are noted in the following
discussion where applicable.
a. Sampling parameters and
frequency. The requirements in today's
final rule for the parameters and
frequency of source water monitoring
are unchanged from those in the
proposed rule [USEPA 2003a), with the
exception of an additional option for
lower frequency Cryptosporidium
sampling by small PWSs. These
requirements reflect recommendations
by the Stage 2 M-DBP Advisory
Committee. They are designed to ensure
a low potential for misclassification in
assigning PWSs to Cryptosporidium
treatment bins. The supporting analyses
are summarized as follows for
Cryptosporidium and indicator (E. coli)
monitoring:
Cryptosporidium Monitoring
EPA analyzed bin misclassification
rates for different Cryptosporidium
monitoring programs by evaluating the
likelihood of two types of errors:
(1) A PWS with a true mean
Cryptosporidium concentration of 0.5-
log (i.e., factor of 3.2) above a bin
boundary is incorrectly assigned to a
lower bin (false negative) and
(2) A PWS with a true mean
concentration of 0.5-log below a bin
boundary is incorrectly assigned to a
higher bin (false positive).
The first type of error, a false negative,
could lead to PWSs not providing an
adequate level of treatment while the
second type of error, a false positive,
could lead to PWSs incurring additional
costs for unnecessary treatment.
EPA evaluated false positive and false
negative rates for monitoring programs
that differed based on the number of
samples collected and the calculation
used to determine the bin classification.
The analysis accounted for the sample
volume assayed, variation in source
water Cryptosporidium occurrence,
variation in analytical method recovery,
and other factors.
Results of this analysis indicate that
PWSs must collect at least 24 samples
in order to keep the likelihood of both
false positives and false negatives at five
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percent or less. Under a monitoring
program involving fewer samples, such
as eight or twelve, a very conservative
calculation for bin classification would
be required to achieve a low false
negative rate (e.g., bin classification
based on the maximum or second
highest sample concentration).
However, such an approach would
result in false positive rates in the range
of 50 to 70 percent. Conversely,
collecting more than 24 samples can
further reduce false positive and false
negative rates, albeit to a small degree.
See the proposed LT2ESWTR for
additional details on this analysis
(USEPA 2003a).
Based on the results of this analysis,
EPA concluded that PWSs operating
year-round should collect at least 24
samples when they monitor fdr
Cryptosporidium. This number of
samples ensures a high likelihood of
appropriate bin classification. Today's
rule does not allow bin classification
based on fewer samples (except in the
case of PWSs operating only part of the
year) as this would involve
unacceptably high false positive or false
negative rates and would, therefore, be
an inappropriate basis to determine
Cryptosporidium treatment
requirements. EPA believes, though,
that PWSs should have the choice to
collect more than 24 samples to further
improve the accuracy of bin
classification, and today's rule allows
this.
In regard to the time frame for
LT2ESWTR monitoring, the Agency
considered the trade-off between
monitoring over a long period to better
capture temporal fluctuations and the
desire to prescribe additional treatment
quickly to PWSs with higher
Cryptosporidium levels. Today's rule
requires large PWSs to evaluate their
source water Cryptosporidium levels
using two years of monitoring. This will
account for some degree of yearly
variability, without significantly
delaying additional public health
protection where needed.
Because many small PWSs will
monitor for E. coli for one year before
monitoring for Cryptosporidium, today's
rule allows two options. Small PWSs
can collect 24 Cryptosporidium samples
over just one year (resulting in a total of
two years of source water monitoring
when E. coli monitoring is considered)
or they can spread their 24
Cryptosporidium samples over two
years. Spreading the Cryptosporidium
monitoring over two years will reduce
the monitoring costs a PWS incurs in a
single year but will not push back the
treatment compliance deadline. This
allowance for small PWSs to monitor for
Cryptosporidium over two years is a
change from the proposal (USEPA
2003a). It stems from recognition of the
benefit this approach will provide to
some small PWSs in budgeting for
monitoring.
Indicator Monitoring
Due to the relatively high cost of
analyzing samples for Cryptosporidium,
the Advisory Committee and EPA
investigated indicators that are less
costly to analyze to determine if any
could be used in place of
Cryptosporidium monitoring. No
indicators were identified that
correlated strongly with
Cryptosporidium and could fully
substitute for Cryptosporidium
monitoring for determining treatment
bin classifications. However, this
investigation did identify an indicator,
E. coli, that can be used to identify some
of the water sources that are unlikely to
exceed a Cryptosporidium level of 0.075
oocysts/L—the level at which filtered
PWSs must provide additional
treatment under the LT2ESWTR.
Data from the ICR and ICRSS were
used in the investigation of indicators.
With these data, E. coli performed the
best in identifying sources with low
Cryptosporidium levels. In addition,
analyzing plants separately based on
source water type was necessary due to
a different relationship between E. coli
and Cryptosporidium in reservoir/lake
sources compared to flowing stream
sources.
The analysis of E. coli concentrations
that could trigger Cryptosporidium
monitoring was based on false negative
and false positive rates. For this
indicator, false negatives occur when
sources do not exceed the E. coli trigger
value but exceed a Cryptosporidium
level of 0.075 oocysts/L. False positives
occur when sources exceed the E. coli
trigger value but do not exceed a
Cryptosporidium level of 0.075 oocysts/
L. The false negative rate is critical
because it characterizes the ability of the
indicator to identify those plants with
higher Cryptosporidium levels that
should conduct Cryptosporidium
monitoring to determine if additional
treatment is needed.
For plants with flowing stream
sources, a mean E. coli trigger
concentration of 50/100 mL produced
zero false negatives for both ICR and
ICRSS data sets. This means that in
these data sets, all plants that exceeded
mean Cryptosporidium concentrations
of 0.075 oocysts/L also exceeded the E.
coli trigger concentration. The false
positive rate for this trigger
concentration was near 50 percent,
meaning it was not highly specific in
targeting only those plants with high
Cryptosporidium levels. However, at a
higher E. coli trigger concentration, such
as 100/100 mL, the false negative rate
increased without a significant
reduction in the false positive rate.
For plants with lake or reservoir
sources, a mean E. coli trigger of 10/100
mL resulted in a false negative rate of 20
percent with ICR data and 67 percent
with ICRSS data. While this false
negative rate in the ICRSS data set
appears high, it is based on just three
plants in this survey that used a
reservoir/lake source and had a mean
Cryptosporidium level above 0.075
oocysts/L. With a lower E. coli trigger
concentration, such as 5/100 mL, the
number of false negatives in both data
sets decreased by one plant, but the
false positive rate increased from 20 to
40 percent.
After evaluating these results, the
Advisory Committee recommended that
all large PWSs monitor for
Cryptosporidium. rather than using E.
coli in a screening analysis. EPA
concurred with this recommendation
because it achieves the highest certainty
that these PWSs will be classified in the
correct Cryptosporidium treatment bin
and provide the appropriate level of
public health protection. In addition,
the Advisory Committee recommended
and today's rule requires that large
filtered PWSs collect E. coli and
turbidity samples along with
Cryptosporidium. EPA will use these
data to confirm or, if necessary, further
refine the use of E. coli and possibly
turbidity as indicators for monitoring by
small filtered PWSs.
Cryptosporidium monitoring places a
relatively greater economic burden on
small PWSs, and EPA will have
additional E. coli and Cryptosporidium
data from large PWS monitoring prior to
the initiation of small PWS monitoring.
Based on these considerations and the
available data on E. coli as an indicator
of sources with lower Cryptosporidium
levels, the Advisory Committee
recommended that small filtered PWSs
initially monitor for E. coli for one year
as a screening analysis. Biweekly
sampling (i.e., 1 sample every two
weeks) for E. coli is required to achieve
high confidence in the results, since no
additional monitoring is required if the
E. coli level is less than the trigger
value. Mean E. coli concentrations
above 10 and 50/100 mL trigger
Cryptosporidium monitoring in PWSs
using reservoir/lake and flowing stream
sources, respectively.
EPA concurred with these
recommendations by the Advisory
Committee and believes they achieve an
appropriate balance between enhancing
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669
public health protection and reducing
the economic impact of today's rule on
small PWSs. Survey data indicate that
approximately 75 to 80 percent of small
PWSs will not exceed the E. coli trigger
values and, consequently, will not be
required to monitor for
Cryptosporidium. Because E. coli is far
less costly to analyze than
Cryptosporidium (costs listed in USEPA
2005a), this approach will significantly
reduce the burden of today's rule for
these PWSs. Further, EPA will review
indicator data from large PWS
monitoring and, if appropriate, issue
guidance to States on alternative
indicator triggers prior to when small
PWSs begin monitoring. Today's rule
allows States to approve alternative
approaches to indicator monitoring for
small PWSs.
EPA could not identify an indicator
screening analysis for unfiltered PWSs.
As described in section IV.C, a mean
Cryptosporidium concentration of 0.01
oocysts/L determines whether unfiltered
PWSs are required to provide 2- or 3-log
Cryptosporidium inactivation. No E.
coli concentration was effective in
determining whether PWSs were likely
to fall above or below this level.
Consequently, today's rule requires all
unfiltered PWSs to monitor for
Cryptosporidium, unless they choose to
provide 3-log Cryptosporidium
inactivation.
fa. Sampling location. The
requirements in today's final rule for the
source water sample collection location
are similar to those in the proposed rule
(USEPA 2003a). They are designed to
achieve two objectives: (1) Characterize
the influent water to the treatment plant
at the time each sample is collected and
(2) ensure that samples are not affected
by treatment chemicals that could
interfere with Cryptosporidium
analysis.
The first objective is the basis for
requiring PWSs that use multiple
sources to either analyze a blended
source sample or calculate a weighted
average of sources that reflects the
influent at the time of sample collection.
It is also the reason that PWSs are
required to sample after certain
pretreatment processes like bank
filtration (described in section IV.D) that
do not involve chemical addition.
The second objective is why PWSs are
generally required to sample upstream
of chemical addition and prior to
backwash addition (for PWSs that
recycle filter backwash). However, EPA
recognizes that in some situations,
sampling prior to chemical addition will
not be feasible and discontinuing
chemical addition for a period of time
prior to sampling will not be advisable.
This situation could occur when a
treatment chemical is added at an intake
that is difficult to access. Further, some
treatment chemicals may not interfere
with Cryptosporidium analyses when
present at very low levels.
Consequently, today's rule allows States
to approve PWSs sampling after
chemical addition when the State
determines that collection prior to
chemical treatment is not feasible and
the treatment chemical is not expected
to interfere with the analysis of the
sample.
EPA believes that States should
review source water monitoring
locations for their PWSs. State review of
monitoring locations will ensure that
PWSs collect source water samples at
the correct location to determine the
appropriate level of public health
protection. Consequently, today's rule
requires PWSs to report a description of
their monitoring location to the State.
This requirement is a change from the
proposed rule, which did not require
PWSs to report a description of their
sampling location (USEPA 2003a). This
change reflects public comment on the
proposal, as described later, which
strongly supported State review of
monitoring locations. If a PWS does not
hear back from the State by the time it
is scheduled to begin sampling, it may
assume that its monitoring location is
acceptable.
c. Sampling schedule. The
requirement in today's final rule that
PWSs must develop a schedule for
sample collection before the start of
monitoring was part of the proposal
(USEPA 2003a). This requirement will
help to ensure that monitoring
determines the mean concentration of
Cryptosporidium in the treatment plant
influent. To achieve this objective, the
timing of sample collection must not be
adjusted in response to fluctuations in
water quality—for example, the
avoidance of sampling when the
influent water is expected to be of poor
quality.
EPA believes that the 5-day window
for sample collection and associated
allowances for sampling outside this
window provide sufficient flexibility. If
circumstances arise that prevent the
PWS from sampling within the
scheduled 5-day window, such as a
weather event or plant emergency, the
PWS must collect a sample as soon as
feasible. In this case, feasibility includes
both the ability of the PWS to safely
collect a sample and the availability of
an approved laboratory to conduct the
analysis within method specifications.
In addition, today's rule allows States to
authorize a different date for collecting
the delayed sample. Such an
authorization may be appropriate in
cases where sampling is significantly
delayed and collecting the delayed
sample during the same time period in
the following year of monitoring is
preferable.
PWSs that collect a sample as
scheduled but are unable to have the
sample analyzed as required due to
problems like shipping or laboratory
analysis must collect a replacement
sample within 21 days of receiving
information that one is needed, unless
the PWS demonstrates that collecting a
replacement sample within this time
frame is not feasible. This time frame is
a minor change from the proposal,
which allowed only 14 days for
resampling (USEPA 2003a), and it
provides greater flexibility for
scheduling replacement samples.
Information that resampling is needed
includes information the PWS acquires
directly, as well as notice from the
shipping company, laboratory, State, or
EPA. Today's rule allows States to
authorize an alternative date for
collection of the replacement sample.
This may be needed for resampling to
occur during the same conditions as the
originally scheduled sample.
If collecting a sample was feasible but
the PWS failed to do so, EPA believes
that the PWSs must develop a revised
sampling schedule and submit it to the
State. This will allow for State
consultation regarding the reason for the
missed sample(s) and strategies for the
PWS to complete the required
monitoring.
d. Plants operating onlv part of the
year. The proposed LT2ESWTR did not
include distinct monitoring
requirements for plants that operate
only part-year. However, EPA requested
comment in the proposal on an
approach to plants that operate only
part-year that is similar to the
requirements in today's final rule
(USEPA 2003a).
Monitoring requirements for plants
that operate only part-year derive from
three considerations: (1) A PWS should
sample only during the months when a
treatment plant operates; (2) the mean
Cryptosporidium level used for bin
classification can be determined with
fewer samples in plants that operate
only part-year because source water
quality typically varies less during the
shorter operating period; and (3) a
minimum number of samples is
necessary to classify any plant in an
LT2ESWTR bin with high confidence.
The basis for the first consideration is
straightforward. Source water
monitoring under the LT2ESWTR is
used to establish treatment
requirements, and these should be based
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on the water quality when a plant is in
operation. The rationale for the second
and third considerations stems from
analyses, similar to those described
previously, of potential
misclassification rates in assigning
plants to LT2ESWTR treatment bins.
Source water variability is one factor
that influences the number of samples
needed to accurately classify plants in
LT2ESWTR treatment bins. As
variability increases, more samples are
needed to determine the mean
Cryptosporidium level with high
confidence. EPA does not have data on
source water variability specifically in
plants that operate only part-year.
However, survey data show that
pathogen levels vary seasonally, and
plants operating part-year will generally
experience less variability during a
given year than plants operating year-
round. Consequently, fewer samples are
typically needed to determine the mean
Cryptosporidium level during the
period of operation for a part-year plant.
Nevertheless, even when a plant
operates for only a few months per year
and source water exhibits little
variability, a minimum number of
samples is necessary for bin
classification. This is due to the
relatively low sample volume, variable
method recovery, nonhomogeneous
distribution of Cryptosporidium in
water, and other factors that limit the
accuracy of any individual sample for
characterizing the source water. Data
suggest that for plants operating for six
months per year or less, collecting a
minimum of six samples per year over
two years may allow bin classification
with comparable accuracy to that
achieved by year-round plants sampling
monthly (USEPA 2005a).
Based on these considerations, today's
rule requires similar source water
monitoring for plants that operate only
part-year during their months of
operation as is required for year-round
plants. However, if the plant is required
to monitor for Cryptosporidium and
operates for six months or less, the PWS
must collect at least six
Cryptosporidium samples per year over
two years.
e. Failing to monitor. Requirements
for PWSs that fail to conduct source
water monitoring are based on the need
for PWSs to determine a
Cryptosporidium bin classification and
provide the appropriate level of public
health protection within the compliance
time frame. The LT2ESWTR proposal
required PWSs that did not complete all
source water monitoring requirements
to meet the requirements of the highest
treatment bin (USEPA 2003a). In today's
final rule, EPA has significantly
changed requirements from those in the
proposal for PWSs that fail to monitor.
These changes are intended to give
States more flexibility in working with
PWSs to fulfill monitoring requirements
and ensure they achieve the appropriate
Cryptosporidium treatment level.
For most monitoring and testing
procedure violations under the
LT2ESWTR, PWSs must provide a Tier
3 public notification, which is standard
for this type of violation under an
NPDWR. However, if a PWS fails to
collect three or more Cryptosporidium
samples, the violation is elevated to a
Tier 2 special public notice. The reason
for elevating the public notice at this
point is the persistence of the violation
and the difficulty the PWS will have in
collecting the required number of
samples for bin classification by the
compliance date. Section IV.H provides
further details on public notice
requirements of the LT2ESWTR.
As described in section IV.G, today's
rule requires bin classification within
six months following the end of the
monitoring period specified for the
PWS. This six-month period provides
some opportunity for collecting and
analyzing missed samples. The number
of samples that can be made up in this
period is limited, though, due to the
need for samples to be evenly
distributed throughout the year, as well
as for PWSs and States to spend time
during this period evaluating
monitoring results to determine bin
classification. In consideration of these
factors, EPA believes that elevating the
public notice when a PWS has missed
three or more Cryptosporidium samples
is appropriate. This violation will end
when the State determines that the PWS
has begun sampling on a schedule to
collect the required number of samples.
Failure by a PWS to collect the
required number of Cryptosporidium
samples for bin classification by the
compliance date is a treatment
technique violation with a required Tier
2 public notice. This violation reflects
the inability of the PWS to determine
and comply with its Cryptosporidium
treatment requirements under the
LT2ESWTR and provide the appropriate
level of public health protection. The
violation ends when the State
determines that the PWS is carrying out
a monitoring plan that will lead to bin
classification. A PWS that has already
provided a Tier 2 public notice for
missing three sampling dates and is
successfully meeting a State-approved
sampling schedule is not required to
issue another public notice for missing
the bin classification date. Alternatively,
the PWS can choose to provide the
highest level of Cryptosporidium
treatment required under the rule,
which is 5.5-log for filtered PWSs and
3-log for unfiltered PWSs.
f. Grandfathering previously collected
data. Requirements for grandfathering
previously collected monitoring data in
today's final rule are similar to those in
the proposal (USEPA 2003a). These
requirements are based on the principle
that to be eligible for grandfathering,
previously collected data must be
equivalent in quality to data that will be
collected under the rule.
The Stage 2 M-DBP Advisory
Committee recommended that EPA
accept previously collected
Cryptosporidium data that are
"equivalent in sample number,
frequency, and data quality (e.g. volume
analyzed, percent recovery) to data that
would be collected under the
LT2ESWTR * * * to determine bin
classification in lieu of further
monitoring" (USEPA 2000a). The
Advisory Committee recognized that
accepting previously collected data
could have a number of benefits,
including early determination of
LT2ESWTR compliance needs,
increasing laboratory capacity, and
allowing PWSs to determine their bin
classification using a larger, and
potentially more representative, data
set.
To ensure equivalent data quality.
today's rule requires that grandfathered
data meet the same requirements for
analytical methods, sampling location,
and sample volume as data collected
under the rule. PWSs must not
selectively report monitoring results for
grandfathering. Further, grandfathered
Cryptosporidium data must generally be
collected at least monthly and on a
regular schedule, with the same
provisions for delayed or replacement
samples as allowed for regular
monitoring. Today's final rule differs
from the proposal, however, in making
allowances for use of previously
collected data where irregularities or
gaps in the sampling frequency occur.
EPA recognizes that when PWSs
collected Cryptosporidium data prior to
the proposed or final LT2ESWTR. there
may have been months when a PWS
either failed to collect or lost a sample
due to problems with equipment,
transportation, laboratory analysis, or
other reasons. If the PWS did not collect
a replacement sample, gaps in the
previously collected data set occurred.
EPA believes that grandfathering of such
a data set may be appropriate despite
these gaps if the PWS conducts
additional monitoring, as necessary, to
"fill-in" gaps and ensure that the data
set is unbiased. Consequently, today's
rule allows grandfathering of data with
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671
gaps in the sampling frequency if
approved by the State.
In addition, if the frequency of
sampling in a previously collected data
set varies, EPA believes the data could
still be appropriate for use in bin
classification. For example, a PWS
might have sampled for
Cryptosporidium once per month for a
number of months and then increased
the sampling frequency to twice per
month. Today's rule allows the use of
such a data set. However, to avoid bias,
the PWS must calculate a monthly
average for each month of sampling and
then determine the bin classification
using these monthly averages, rather
than the individual sample
concentrations.
Today's rule requires PWSs that plan
to grandfather monitoring data to notify
EPA or the State regarding the number
and time span of sample results no later
than three months prior to when the
PWS must begin monitoring. The timing
for submission of this notice is
concurrent with the submission of a
sampling schedule. This notification is
necessary for the State to determine that
a PWS is not required to submit a
sampling schedule (when a PWS will
fully comply with initial monitoring
through grandfathering) or that a
sampling schedule may include less
than the full number of required
samples (when a PWS will conduct new
monitoring in conjunction with
grandfathering to complete a data set).
Further, this notice will assist EPA and
States in determining the resources
necessary to ensure timely review of
grandfathered data.
PWSs must submit all monitoring
results for grandfathering to EPA or the
State, along with required supporting
documentation, no later than two
months after the PWS is required to
begin monitoring. This timing will
allow a PWS to continue collecting data
for grandfathering until the month the
PWS is required to begin monitoring
under today's rule, plus an additional
two months for sample analysis and
compilation of the data for submission.
This reporting deadline for
grandfathering monitoring results is a
change from the proposed rule. In the
proposal, a PWS that intended to
grandfather data in lieu of conducting
new monitoring under the rule had to
submit its grandfathered results no later
than four months prior to when the
PWS was otherwise required to begin
monitoring under the rule. This
proposed approach had the shortcoming
that a PWS could not complete its
monitoring for grandfathering within
this four month period. In today's final
rule, a PWS may continue monitoring
for grandfathering all the way until the
date when the PWS must begin
monitoring under the rule, if necessary.
PWSs that conclude their monitoring for
grandfathering earlier may submit the
data at an earlier date.
g. Ongoing watershed assessment.
Treatment requirements under the
LT2ESWTR are based on source water
quality. Consequently, today's rule
requires watershed assessment and, as
described in the next section, a second
round of monitoring following initial
bin classification to determine if source
water quality has changed to the degree
that the treatment level should be
modified. These requirements are
unchanged from those in the proposed
LT2ESWTR' (USEPA 2003a), with the
exception of an allowance for States to
use programs other than the sanitary
survey to assess changes in the
watershed.
Today's rule leverages the existing
requirement for States to perform
sanitary surveys on surface water PWSs.
During the source water review in the
sanitary survey, today's rule requires
States to determine if significant
changes have occurred in the watershed
that could lead to increased
contamination by Cryptosporidium. The
State can also choose to make this
determination through an equivalent
review of the source water under a
program other than the sanitary survey,
such as a Source Water Protection
Assessment. If the State determines that
significant changes have occurred, the
State may specify that the PWS conduct
additional source water monitoring or
treat the potential contamination. This
approach allows the PWS and State to
respond to a significant change in
source water quality prior to initiating a
second round of monitoring or any time
thereafter.
h. Second round of monitoring. A
more rigorous reassessment of the
source water occurs through a second
round of monitoring that begins six
years after initial bin classification. If
EPA does not develop and finalize
modifications to the LT2ESWTR prior to
the date when PWSs must begin the
second round of monitoring, then this
second round must conform to the same
requirements that applied to the initial
round of monitoring. PWSs may be
classified in a different treatment bin,
depending on the results of the second
round of monitoring.
The Stage 2 M-DBP Advisory
Committee recommended that EPA
initiate a stakeholder process several
years prior to the second round of
monitoring to review new information
and determine if today's rule should be
modified. If the Agency modifies the
LT2ESWTR, the second round of
monitoring would potentially involve a
new analytical method and a different
treatment bin structure.
3. Summary of Major Comments
Public comment on the August 11,
2003, LT2ESWTR proposal generally
supported the use of source water
monitoring to determine additional
treatment requirements. The following
discussion summarizes major comments
and EPA's responses in regard to
sampling parameters and frequency,
sampling location, sampling schedule,
monitoring plants that operate only
part-year, failing to monitor, providing
treatment instead of monitoring,
grandfathering previously collected
data, ongoing source water assessment,
second round of monitoring, and new
source monitoring.
a. Sampling parameters and
frequency. Most commenters supported
the proposed requirements for large
PWSs to sample monthly for
Cryptosporidium, as well as for E. coli
and turbidity in filtered PWSs, for 24
months. Alternatives recommended by
some commenters included ending
monitoring after one year if no oocysts
are detected, allowing large PWSs to use
an E. coli screening analysis to
determine if Cryptosporidium
monitoring is necessary, and using
watershed data to determine treatment
needs instead of source water
monitoring.
In response, EPA continues to believe
that large PWSs should complete 24
months of Cryptosporidium monitoring,
regardless of the first-year results, in
order to capture a degree of annual
variability in Cryptosporidium
occurrence. Moreover, for the reasons
discussed previously in this preamble,
EPA continues to support the Advisory
Committee recommendation that all
large PWSs should monitor for
Cryptosporidium, rather than use the E.
coli screening analysis. EPA is not
aware of studies that support the use of
other watershed data in place of
Cryptosporidium monitoring to
determine treatment needs.
Regarding requirements for small
PWSs, most commenters supported the
E. coli screening analysis for small
filtered PWSs. Several commenters
recommended more options for
Cryptosporidium monitoring by small
PWSs, such as allowing monitoring to
be spread over two years, instead of the
one year required in the proposal, or
allowing fewer samples. EPA agrees that
budgeting for Cryptosporidium
monitoring by some small PWSs will be
easier if it is spread over two years, and
today's rule allows this as an option.
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However, based on the analysis of false
negative and false positive rates
described previously, EPA continues to
believe that at least 24 Cryptosporidium
samples are necessary to determine the
appropriate bin classification for year-
round plants.
b. Sampling location. With respect to
sampling location requirements, several
commenters recommended that PWSs
be allowed to collect samples either
before or after pretreatment processes.
These commenters stated that the
chemicals used in pretreatment
processes are unlikely to affect the
analysis of Cryptosporidium oocysts at
typical concentrations. Further, where
sampling is conducted prior to a
pretreatment process like
presedimentation, commenters
supported allowing PWSs to receive
additional treatment credit for the
process.
In response, EPA continues to believe
that common pretreatment chemicals
like oxidants and coagulants have the
potential to adversely affect the
performance of Cryptosporidium
analytical methods. Consequently,
today's rule requires that in most cases,
PWSs must sample upstream of
chemical addition. Where PWSs sample
prior to pretreatment processes like
presedimentation with coagulation, they
are eligible to receive additional
treatment credit for the process.
However, if sampling prior to chemical
addition is not feasible for a particular
plant and the treatment chemical is
present at a very low level that is
unlikely to interfere with sample
analysis, the State may approve
sampling after chemical addition.
Many commenters recommended that
States approve sampling locations for
their PWSs. Commenters indicated that
State review and approval of monitoring
plans will help to prevent confusion
and PWSs potentially sampling at an
incorrect location. EPA agrees with
these commenters and has established a
requirement in today's rule for PWSs to
report a description of the sampling
location to the State. If a PWS does not
hear back from the State by the time it
is scheduled to begin sampling, it may
assume that its monitoring location is
acceptable.
c. Sampling schedule. In regard to
sampling schedule requirements,
several commenters requested that
PWSs be given a time window larger
than 5 days around scheduled sampling
dates to collect samples. Recommended
alternatives included a 7 or 9-day
window, or only requiring that PWSs
collect a sample within a specified
month. In addition, commenters
identified situations that interfere with
sample collection, such as plant
interruptions and laboratory or
transportation problems, and noted that
some of these are outside the conditions
under which the proposal allowed a
PWS to collect a delayed or replacement
sample without penalty.
In response, EPA continues to believe
that for routine sample collection, a 5-
day window provides sufficient
flexibility, given that PWSs will pick the
sampling days and can schedule around
holidays, weekends, and other times
when sampling would be problematic.
However, today's rule allows PWSs to
sample outside of this window without
penalty if necessary due to unforeseen
conditions. Further, if a PWS collects a
sample but is unable to have it analyzed
due to problems with equipment,
transportation or the laboratory, today's
rule allows the PWS to collect a
replacement sample without penalty.
In regard to the time frame for
collecting missed or replacement
samples, commenters recommended a
number of approaches. These include
adding extra sampling days to the
original sampling schedule, which a
PWS could then use in the event of
missed sampling dates, and allowing
PWSs to collect make-up samples either
immediately after the scheduled
sampling date or at the end of the
monitoring period.
In general, EPA considers it preferable
for PWSs to collect missed or
replacement samples as close as is
feasible to scheduled sampling dates.
However, if there is a significant delay
with respect to the original sampling
date, collecting make-up samples at an
alternate time may be appropriate to
ensure that sampling results are
seasonally representative. Therefore,
today's rule requires PWSs to collect a
missed sample as close as is feasible to
the scheduled sampling date, and to
collect replacement samples within 21
days of receiving information that one is
needed, unless doing so within this time
frame is not feasible. However, the State
can authorize alternative sampling dates
so that monitoring is not seasonally
biased. This could include sampling
during the same time in the following
year, if the missed sample occurred
during the first year of monitoring, or
sampling after the end of the scheduled
monitoring period.
d. Plants operating only part of the
year. Commenters on monitoring
requirements for surface water plants
that operate for only part of the year
generally recommended that sampling
occur only during the period of
operation. However, several different
options were put forward for how the
sampling be conducted. Some
commenters recommended a minimum
of 12 samples per year for two years
distributed evenly over the period that
the plant operates. Others suggested
allowing the PWS to collect the required
number of samples over a longer time
period in order to limit the frequency of
required samples when the plant is
operating. Several commenters said that
State input is critical to determining the
appropriate monitoring period since
States may have historical knowledge of
plant operating practices.
In response, EPA agrees that
monitoring of plants that operate only
part-year under today's rule should be
conducted only during months when
the plant is operating, unless the State
determines that a longer monitoring
period is appropriate due to historical
operating practices. Further, plants that
operate only part-year should maintain
the same sampling frequency as plants
operating year-round, with the
exception that plants monitoring for
Cryptosporidium must collect at least
six samples per year to allow for
appropriate bin classification. EPA does
not believe extending monitoring over
more years in plants that operate only
part-year is appropriate, as this would
delay the installation of additional
treatment where needed.
e. Failing to monitor. Most
commenters opposed automatically
classifying PWSs in the highest
treatment bin (Bin 4) if they fail to
complete required monitoring, as the
proposed rule stipulated. Commenters
suggested alternative approaches, such
as giving States the flexibility to address
missed samples using current
enforcement mechanisms, classifying a
PWS only one level higher than the bin
determined by the collected data,
allowing an additional year of sampling,
and allowing States to use other
information (e.g., sanitary surveys, other
monitoring data) to aid in the
classification. A few commenters,
however, supported Bin 4 classification
for PWSs that fail to monitor, on the
basis that any other approach would
create an incentive for PWSs to stop
testing if poor water quality is
suspected.
EPA agrees that States should have
flexibility in dealing with PWSs that fail
to monitor. Further, providing the
highest level of treatment may not be in
the best interests of consumers where a
PWS has minor problems in carrying
out source water monitoring. However,
EPA also believes that violations for
monitoring failures must reasonably
ensure that PWSs complete monitoring
as required to determine a bin
classification within the compliance
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673
date. Failure to do so would potentially
compromise public health protection.
Based on these considerations, EPA
has not established an automatic Bin 4
classification for monitoring failures
under today's rule. Rather, if a PWS
misses three or more Cryptosporidium
samples, this persistent violation
requires a Tier 2 public notice (other
violations require a Tier 3 notice).
Further, if a PWS is unable to determine
a bin classification by the compliance
date due to failure to collect the
required number of Cryptosporidium
samples, this is a treatment technique
violation with a required Tier 2 public
notice (unless the PWS has already
issued a Tier 2 notice for missing 3
Cryptosporidium samples and is
monitoring on a State-approved
schedule). These violations last until the
State determines that a PWS has begun
monitoring on a schedule that will lead
to bin classification or the PWS agrees
to install treatment instead of
monitoring.
f. Providing treatment instead of
monitoring. Commenters supported the
option for a PWS to provide the highest
level of Cryptosporidium treatment
required under today's rule rather than
conducting source water monitoring.
Several commenters recommended that
a PWS should be allowed to take this
option after having initiated monitoring.
EPA agrees, and today's rule allows a
PWS to stop monitoring at any time by
notifying the State that it will provide
5.5-log Cryptosporidium treatment for
filtered PWSs or 3-log Cryptosporidium
inactivation for unfiltered PWSs by the
compliance deadline specified in
section IV.G.
g. Grandfathering previously collected
data. With respect to grandfathering
previously collected data, many
commenters expressed concern with a
proposed requirement that samples
must have been collected in equal time
intervals. Commenters stated that
although PWSs may have sampled on a
regular schedule, previously collected
data sets are likely to have gaps due to
samples rejected for method QC
violations or periods when the PWS was
unable to collect a sample. In addition,
there are instances where PWSs have
changed the frequency of sampling,
such as from monthly to twice per
month.
EPA agrees that if a PWS has collected
samples according to a regular schedule
and met other data quality standards,
then rejecting a large data set due to
isolated gaps in the sampling frequency
would be inappropriate. Consequently,
today's rule allows States to approve
grandfathering of previously collected
data with omissions in the sampling
interval, provided the PWS conducts
additional monitoring if required by the
State to ensure the data set is seasonally
representative. Further, PWSs may
grandfather previously collected data
sets in which the sampling frequency
varies, as long as samples were collected
at least monthly. In this situation, PWSs
must use monthly average
concentrations, rather than individual
sample concentrations, for bin
classification.
With respect to data quality
standards, such as meeting analytical
method QC criteria, sampling at the
correct location, and analyzing the
minimum sample volume, several
commenters stated that EPA should
apply the same acceptance standards to
previously collected data as are applied
to data collected under today's rule.
Other commenters, though, suggested
that States should have the flexibility to
accept previously collected data that
deviate from the data quality standards
for monitoring under the rule. These
commenters stated that such data sets
might include samples collected over a
longer period of time and may reflect
more worst-case weather events.
In response, EPA believes that data
quality standards should be uniformly
applied under today's rule, so that
previously collected data should not be
held to a lower standard than new data
or evaluated differently from State to
State. The requirements in today's rule
with respect to Cryptosporidium
analytical methods and minimum
sample volume reflect recommendations
of the Advisory Committee, which also
recommended that the same data quality
standards be applied for grandfathering.
Further, because today's rule allows
PWSs to collect make-up samples to
address gaps in previously collected
data sets, PWSs will have the
opportunity to collect make-up samples
for results that are rejected due to data
quality standards without losing an
entire data set.
In regard to notification of the
acceptability of data for grandfathering,
commenters recommended that if
previously collected data submitted by
a PWS are rejected, the PWS should
have at least two months between
notification and the date new
monitoring must be initiated. These two
months will give the PWS time to
address rejection of the data and prepare
for sampling. EPA agrees with this
recommendation. Under today's rule, if
a PWS properly submits a complete data
set for grandfathering and the PWS must
conduct new monitoring due to
rejection of the data, the PWS has at
least two months following notification
by the State to initiate sampling.
h. Ongoing watershed assessment.
Commenters asked for greater flexibility
in the requirement for States to
determine whether there have been
significant changes in the watersheds of
their PWSs that could lead to increased
contamination. The proposed rule
specified that States must make this
determination during sanitary surveys.
However, several commenters noted
that some States perform source water
protection assessments on the same
frequency as sanitary surveys, and these
detailed assessments might be a better
mechanism to monitor changes in the
watershed. EPA agrees and today's rule
allows States to determine whether
significant changes have occurred in the
watershed through either a sanitary
survey or an equivalent review of the
source water under another program.
i. Second round of monitoring. Some
commenters supported the proposed
requirement for a second round of
source water monitoring, but most
opposed requiring it for all PWSs. These
commenters recommended that States
should be authorized to use sanitary
surveys, source water assessments,
ambient water quality data, treatment
plant data, and other information to
determine if a second round of
monitoring is necessary for a PWS.
Some commenters suggested that EPA
fund research to allow the use of
finished water monitoring as the
determinant for treatment requirements
in a second round of monitoring.
In response, EPA continues to believe
that PWSs should conduct a second
round of monitoring to determine if the
level of treatment required as a result of
the first round of monitoring is still
appropriate. Consequently, today's rule
requires this. However, EPA agrees that
prior to a second round of monitoring,
the Agency should evaluate the results
of the first round of monitoring, along
with whatever new information is
available on Cryptosporidium analytical
methods, risk, and other relevant issues.
If EPA determines that there should be
changes to the requirements for a
second round of monitoring in today's
rule, the Agency will issue a new rule
establishing those changes.
j. New source monitoring. EPA
requested comment in the proposal on
monitoring requirements for new plants
and sources (USEPA 2003a). Most
commenters recommended that new
plants and sources undergo monitoring
equivalent to that required for existing
plants and sources, and suggested that
States should have discretion to
determine when monitoring should take
place. EPA agrees with these
recommendations and today's rule
requires PWS to conduct source water
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monitoring for new plants and sources
on a schedule approved by the State.
This schedule must include dates for
the PWS to determine its treatment bin
classification and, if necessary, comply
with additional Cryptosporidium
treatment requirements.
B. Filtered System Cryptosporidium
Treatment Requirements
1. Today's Rule
Today's rule requires filtered PWSs
using surface water or GWUDI sources
to provide greater levels of treatment if
their source waters have higher
concentrations of Cryptosporidium.
Specifically, filtered PWSs are classified
in one of four treatment bins based on
results from the source water
monitoring described in the previous
section. PWSs classified in the lowest
concentration bin are subject to no
additional treatment requirements,
while PWSs assigned to higher
concentration bins must reduce
Cryptosporidium levels beyond IESWTR
and LT1ESWTR requirements. All PWSs
must continue to comply with the
requirements of the SWTR, IESWTR,
and LTlESWTR, as applicable.
This section addresses procedures for
classifying filtered PWSs in
Cryptosporidium treatment bins and the
treatment requirements associated with
each bin. Section IV.D presents the
treatment and control options,
collectively termed the "microbial
toolbox," that PWSs must use to meet
additional Cryptosporidium treatment
requirements under today's rule.
a. Bin classification. After completing
initial source water monitoring, filtered
PWSs must calculate a Cryptosporidium
bin concentration for each treatment
plant where Cryptosporidium
monitoring is required. This
Cryptosporidium bin concentration is
used to classify filtration plants in one
of the four treatment bins shown in
Table IV.B-1.
TABLE IV.B-1 .—BIN CLASSIFICATION TABLE FOR FILTERED PWSs
For PWSs that are
with a Cryptosporidium bin concentration of .
The bin classification
is ...
* required to monitor for Cryptosporidium
* * serving fewer than 10,000 people and NOT re-
quired to monitor for Cryptosporidium 1
less than 0.075 oocysts/L
0.075 oocysts/L or higher, but less than 1.0 oocysts/L ..
1.0 oocysts/L or higher, but less than 3 0 oocysts/L .. ..
3 0 oocysts/L or higher
NA
Bin 1.
Bin 2.
Bin 3.
Bin 4
Bin 1
1 Filtered PWSs serving fewer than 10,000 people are not required to monitor for Cryptosporidium if they monitor for E coh and demonstrate a
mean concentration of E. coh less than or equal to 10/100 mL for lake/reservoir sources or 50/100 mL for flowing stream sources or do not ex-
ceed an alternative State-approved indicator trigger (see section IV A 1)
In general, the Cryptosporidium bin
concentration is calculated by averaging
individual sample results from one or
more years of monitoring. Specific
procedures vary, however, depending
on the frequency and duration of
monitoring. These procedures are as
follows:
(1) For PWSs that collect a total of at
least 24 but not more than 47
Cryptosporidium samples over two or
more years, the Cryptosporidium bin
concentration is equal to the highest
arithmetic mean of all sample
concentrations in any 12 consecutive
months of Cryptosporidium monitoring.
(2) For PWSs that collect a total of at
least 48 samples, the Cryptosporidium
bin concentration is equal to the
arithmetic mean of all sample
concentrations.
(3) For PWSs that serve fewer than
10,000 people and monitor for
Cryptosporidium for only one year (i.e.,
collect 24 samples in 12 months), the
Cryptosporidium bin concentration is
equal to the arithmetic mean of all
sample concentrations.
(4) For PWSs with plants that operate
only part-year that monitor for less than
12 months per year, the
Cryptosporidium bin concentration is
equal to the highest arithmetic mean of
all sample concentrations during any
year of Cryptosporidium monitoring.
In data sets with variable sampling
frequency, PWSs must first calculate an
arithmetic mean for each month of
sampling and then apply one of these
four procedures using the monthly
mean concentrations. As described in
section IV.A, PWSs may grandfather
previously collected Cryptosporidium
data where the sampling frequency
varies (e.g., one year of monthly
sampling and one year of twice-per-
month sampling).
Filtered PWSs serving fewer than
10,000 pedple are not required to
monitor for Cryptosporidium if they
demonstrate a mean E. coli
concentration less than or equal to 10/
100 mL for lake/reservoir sources or 50/
100 mL for flowing stream sources or do
not exceed an alternative State-
approved indicator trigger. PWSs that
meet this criterion are classified in Bin
1 as shown in Table IV.B-1.
When determining the
Cryptosporidium bin concentration,
PWSs must calculate individual sample
concentrations as the total number of
oocysts counted, divided by the volume
assayed (see section V.K for details). In
samples where no oocysts are detected,
the result is assigned a value of zero for
the purpose of calculating the bin
concentration. Sample analysis results
are not adjusted for analytical method
recovery or the percent of
Cryptosporidium oocysts that are
infectious.
PWSs must report their treatment bin
classification to the State for approval
following initial source water
monitoring (see section IV.G for specific
compliance dates). The report must
include a summary of the data and
calculation procedure used to determine
the bin concentration. If EPA does not
amend today's rule before the second
round of monitoring described in
section IV.A, PWSs must recalculate
their bin classification after completing
the second round of monitoring and
report the results to the State for
approval. If the State does not respond
to a PWS regarding its bin classification
after either report, the PWS must
comply with the Cryptosporidium
treatment requirements of today's rule
based on the reported bin classification.
b. Bin treatment requirements. Table
IV.B-2 shows the additional
Cryptosporidium treatment
requirements associated with the four
treatment bins for filtered PWSs under
today's rule. All filtered PWSs must
comply with these treatment
requirements based on their bin
classification, which must be
determined using the procedures just
described.
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675
TABLE IV.B-2.—TREATMENT REQUIREMENTS FOR LT2ESWTR BIN CLASSIFICATIONS
If your bin classification
is ...
Bin 1
Bin 2
Bin 3
Bin 4
And you use the following filtration treatment in full compliance with the SWTR, IESWTR, and LT1ESWTR (as ap-
plicable), then your additional treatment requirements are
Conventional filtration treatment ' , di-
atomaceous earth filtration, or slow
sand filtration
No additional treatment
1-log treatment2
2-log treatment3
2. 5-loa treatment3
Direct filtration
No additional treatment
1.5-log treatment2
2 5-log treatment 3
3-loa treatment3
Alternative filtration technologies
No additional treatment.
As determined by the State 2 4
As determined by the State ^ ^
As determined bv the State 3 6
1 Applies to a treatment tram using separate, sequential, unit processes for coagulation/flocculation, clarification, and granular media filtration
Clarification includes any solid/liquid separation process following coagulation where accumulated solids are removed during this separate com-
ponent of the treatment system.
2PWSs may use any technology or combination of technologies from the microbial toolbox in section IV.D.
3 PWSs must achieve at least 1-log of the required treatment using ozone, chlorine dioxide, UV, membranes, bag filtration, cartridge filtration,
or bank filtration
4Total Cryptosporidium removal and mactivation must be at least 4.0 log.
5Total Cryptosporidium removal and mactivation must be at least 5.0 log.
6Total Cryptosporidium removal and inactivation must be at least 5 5 log.
The total Cryptosporidium treatment
required for plants in Bins 2, 3, and 4
is 4.0-log, 5.0-log, and 5.5-log,
respective!}'. Conventional treatment
(including softening), slow sand, and
diatomaceous earth filtration plants in
compliance with the IESWTR or
LT1ESWTR, as applicable, receive a
prescribed 3.0-log Cryptosporidium
treatment credit toward these total bin
treatment requirements. Accordingly,
these plant types must provide 1.0- to
2.5-log of additional treatment when
classified in Bins 2-4, respectively.
Direct filtration plants in compliance
with existing regulations receive a
prescribed 2.5-log treatment credit and,
consequently, must achieve 0.5-log
greater treatment to comply with Bins
2-4. Section IV.D describes how States
may award a level of treatment credit
that differs from the prescribed credit
based on a demonstration of
performance by the PWS.
For PWSs using alternative filtration
technologies, such as membranes, bag
filters, or cartridge filters, no prescribed
treatment credit is available because the
performance of these processes is
specific to individual products.
Consequently, when PWSs using these
processes are classified in Bins 2—4, the
State must determine additional
treatment requirements based on the
credit the State awards to a particular
technology. The additional treatment
requirements must ensure that plants
classified in Bins 2-4 achieve total
Cryptosporidium reductions of 4.0- to
5.5-log, respectively. Section IV.D
describes challenge testing procedures
to determine treatment credit for
membranes, bag filters, and cartridge
filters.
PWSs can achieve additional
Cryptosporidium treatment credit
through implementing pretreatment
processes like presedimentation or bank
filtration, by developing a watershed
control program, and by applying
additional treatment steps like ozone,
chlorine dioxide, UV, and membranes.
In addition, PWSs can receive a higher
level of credit for existing treatment
processes through achieving very low
filter effluent turbidity or through a
demonstration of performance. Section
IV.D presents criteria for awarding
Cryptosporidium treatment credit to
these and other treatment and control
options, which collectively comprise
the microbial toolbox.
PWSs in Bin 2 can meet additional
Cryptosporidium treatment
requirements by using any option or
combination of options from the
microbial toolbox. For Bins 3 and 4,
PWSs must achieve at least 1-log of the
additional treatment requirement by
using ozone, chlorine dioxide, UV,
membranes, bag filtration, cartridge
filtration, or bank filtration.
2. Background and Analysis
Today's rule will increase protection
against Cryptosporidium and other
pathogens in PWSs with the highest
source water contamination levels. This
targeted approach builds upon existing
regulations under which all filtered
PWSs must provide the same level of
treatment regardless of source water
quality. EPA's intent with today's rule is
to ensure that PWSs with higher risk
source waters achieve public health
protection commensurate with PWSs
with less contaminated sources.
The Cryptosporidium treatment
requirements for filtered PWSs in
today's rule are unchanged from the
August 11, 2003 proposal (USEPA
2003a) and reflect consensus
recommendations by the Stage 2 M-DBP
Advisory Committee (USEPA 2000a).
The following discussion summarizes
the Agency's basis for establishing risk-
targeted Cryptosporidium treatment
requirements and for setting the specific
bin concentration ranges and treatment
requirements that apply to filtered
PWSs in today's rule.
a. Basis for targeted treatment
requirements. In developing today's
rule, EPA evaluated the degree to which
new information on Cryptosporidium
warranted moving beyond existing
regulations. As discussed in section III,
the IESWTR established a
Cryptosporidium MCLG of zero and
requires large filtered PWSs to achieve
2-log Cryptosporidium removal. The
LTlESWTR extended this requirement
to small PWSs. After these rules were
promulgated, advances were made in
analytical methods and treatment for
Cryptosporidium, and EPA collected
new information on Cryptosporidium
occurrence and infectivity.
Consequently, EPA assessed the
implications of these developments for
further controlling Cryptosporidium to
approach the zero MCLG.
The risk-targeted approach for filtered
PWSs in today's final rule stems from
four general findings based on new
information on Cryptosporidium:
(1) New data on Cryptosporidium
infectivity suggest that the risk
associated with a particular level of
Cryptosporidium is most likely higher
than EPA estimated at the time of earlier
rules;
(2) New data on Cryptosporidium
occurrence indicate that levels are
relatively low in most water sources, but
a subset of sources has substantially
higher concentrations;
(3) The finding that UV light can
readily inactivate Cryptosporidium, as
well as other technology developments,
makes achieving high levels of
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676 Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
treatment for Cryptosporidium feasible
for PWSs of all sizes; and
(4) EPA Methods 1622 and 1623 are
capable of assessing annual mean levels
of Cryptosporidium in drinking water
sources.
These findings led EPA to conclude
that most filtered PWSs currently
provide sufficient treatment for
Cryptosporidium, but additional
treatment is needed in those PWSs with
the highest source water
Cryptosporidium levels to protect
public health. Further, PWSs can
characterize Cryptosporidium levels in
their source waters with available
analytical methods and can provide
higher levels of treatment with available
technologies. Consequently, risk-
targeted treatment requirements for
Cryptosporidium based on source water
contamination levels are appropriate
and feasible to implement.
b. Basis for bin concentration ranges
and treatment requirements. To
establish the risk-targeted treatment
requirements in today's rule, EPA had to
determine the degree of treatment that
should be required for different source
water Crvptosporidium levels to protect
public health. This determination
involved addressing several questions:
• What is the risk associated with
Cryptosporidium in a drinking water
source?
• How much Cryptosporidium
removal do filtration plants achieve?
• What is the appropriate statistical
measure for classifying PWSs into
treatment bins?
• What degree of additional treatment
is needed for higher source water
Cryptosporidium levels?
• How should PWSs calculate their
treatment bin classification?
This section summarizes how EPA
evaluated these questions in developing
today's rule. See the proposed
LT2ESWTR for further details [USEPA
2003a).
What is the Risk Associated With
Cryptosporidium in a Drinking Water
Source?
The risk of infection from
Cryptosporidium in drinking water is a
function of exposure (i.e., the dose of
oocysts ingested) and infectivity (i.e.,
likelihood of infection as a function of
ingested dose). Primary (i.e., direct)
exposure to Cryptosporidium depends
on the concentration of oocysts in the
source water, the fraction removed by
the treatment plant, and the volume of
water consumed (secondary exposure
occurs through interactions with
infected individuals). Thus, the daily
risk of infection (DR) is as follows:
DR = (oocysts/L in source water) x
(fraction remaining after treatment) x
(liters consumed per day) x (likelihood
of infection per oocyst dose).
Assuming 350 days of consumption
per year for people served by
community water systems (CWSs), the
annual risk (AR) of infection is as
follows:
AR = 1 - (1 - DR) 35°.
As discussed in section III.E, EPA has
estimated the mean likelihood of
infection from ingesting one
Cryptosporidium oocyst to range from 4
to 16 percent. Median individual daily
water consumption is estimated as 1.07
L/day. Figure IV.B-l illustrates ranges
for the annual risk of infection by
Cryptosporidium in CWSs based on
these values for different source water
infectious oocyst concentrations and
treatment plant removal efficiencies.
The dashed lines represent the
uncertainty associated with
Cryptosporidium infectivity for each
log-removal curve. See Chapter 5 of the
LT2ESWTR Economic Analysis for
details (USEPA 2005a).
BILLING CODE 6560-50-P
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations 677
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BILLING CODE 6560-so-c concentration of infectious 0.1 oocysts/L and the plant achieved 3-
The results in Figure IV.B-1 show, for Cryptosporidium in the source water of log removal, the mean annual risk of
example, that if a treatment plant had a
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678
Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
Cryptosporidium infection would range
from 0.0017 to 0.0060 (17 to 60
infections per 10,000 consumers). In
comparison, if the same plant had a
source water infectious
Cryptosporidium level of 0.01 oocysts/
L, the annual infection risk would range
from 1.7 to 6 per 10,000 consumers.
How much Cryptosporidium removal do
filtration plants achieve?
The amount of Cryptosporidium
removal that filtration plants achieve
was a key factor in assessing the
additional treatment that plants with
higher source water Cryptosporidium
levels should provide. To evaluate this
factor. EPA reviewed studies of
Cryptosporidium removal by common
treatment processes. As described in the
proposal for today's rule, these
processes were conventional treatment,
direct, slow sand, and diatomaceous
earth filtration, as well as membrane.
bag, and cartridge filtration (USEPA
2003a).
The majority of plants treating surface
water use conventional treatment,
which is defined in 40 CFR 141.2 as
coagulation, flocculation,
sedimentation, and filtration. In the
proposal, EPA reviewed studies of
conventional treatment by Dugan et al.
(2001), Nieminski and Bellamy (2000),
McTigue et al. (1998), Patania et al.
(1999), Huck et al. (2000). Emelko et al.
(2000), and Harrington et al. (2001).
Based on these studies, EPA estimated
that conventional treatment plants in
compliance with the IESWTR or
LTlESWTR typically achieve a
Cryptosporidium removal efficiency of
approximately 3-log. Consequently,
conventional treatment plants receive 3-
log credit toward Cryptosporidium
treatment requirements under today's
rule.
This 3-log credit for conventional
treatment is consistent with the Stage 2
M-DBP Agreement in Principle (USEPA
2000a), which states as follows:
"The additional treatment requirements in
the bin requirement table are based, in part,
on the assumption that conventional
treatment plants in compliance with the
IESWTR achieve an average of 3 logs removal
of Cryptosporidium."
The M-DBP Advisory Committee did
not recommend a level of
Cryptosporidium treatment credit for
otber types of filtration plants.
EPA also reviewed studies of the
performance of clarification processes
like dissolved air flotation, which can
be used in place of sedimentation in a
conventional treatment train (Gregory
and Zabel 1990, Plummer et al. 1995,
Edzwald and Kelley 1998). These
studies indicate that plants using
clarification processes other than
sedimentation that are located after
coagulation and prior to filtration can
achieve performance equivalent to
conventional treatment plants. As a
result, any treatment train that includes
coagulation/flocculation. clarification,
and granular media filtration is regarded
as conventional treatment for purposes
of awarding treatment credit under
today's rule. The clarification step must
be a solid/liquid separation process
where accumulated solids are removed
during this separate component of the
treatment system.
Direct filtration plants use
coagulation, flocculation, and filtration
processes just as conventional treatment
plants do, but they lack a sedimentation
basin or equivalent clarification process.
In the proposal, EPA reviewed studies
of sedimentation by Dugan et al. (2001),
States et al. (1997),'Edzwald and Kelly
(1998), Payment and Franco (1993),
Kelly et al. (1995), and Patania et al.
(1995). Results from these studies
demonstrate that sedimentation basins
can achieve 0.5-log or greater
Cryptosporidium removal. In addition.
some studies have observed that direct
filtration achieves less Cryptosporidium
removal than conventional treatment
(Patania et al. 1995) and the incidence
of Cryptosporidium in the treated water
is higher (McTigue et al. 1998). Given
these findings, EPA has awarded direct
filtration plants a 2.5-log credit towards
Cryptosporidium treatment
requirements under today's rule (i.e.,
0.5-log less credit than for conventional
treatment).
Slow sand filtration involves passing
raw water through a bed of sand at low
velocity and without prior coagulation.
Diatomaceous earth filtration is a
process by which a filtration medium is
initially deposited onto a support
membrane and medium is added
throughout the operation to keep the
filter from clogging. In the proposal,
EPA reviewed slow sand filtration
studies by Fogel et al. (1993). Hall et al.
(1994), Schuler and Ghosh (1991), and
Timms et al. (1995) and diatomaceous
earth filtration studies by Schuler and
Gosh (1990) and Ongerth and Hutton
(1997, 2001). For both processes, these
studies indicate that a well-designed
and properly operated filter can achieve
Cryptosporidium removal efficiencies
similar to those observed for
conventional treatment plants. Slow
sand and diatomaceous earth filtration
plants, therefore, receive a 3-log credit
towards Cryptosporidium treatment
requirements under today's rule.
Estimating a typical Cryptosporidium
removal efficiency for filtration
technologies like membranes, bag filters,
and cartridge filters is not possible
because the performance of such filters
is specific to a particular product. As a
result, credit for these devices must be
determined by the State based on
product-specific testing using the
procedures described in section IV.D or
other criteria approved by the State.
Table IV.B-3 summarizes the credits
various types of filtration plants receive
toward Cryptosporidium treatment
requirements under today's rule. This
credit determines the degree of
additional treatment that plants
classified in Bins 2-4 must apply, as
shown in Table IV.B-2.
TABLE IV.B-3.—CRYPTOSPORIDIUM TREATMENT CREDIT TOWARDS LT2ESWTR REQUIREMENTS "
Plant type
Treatment credit
Conventional treatment (in-
cludes softening)
3.0-loq
Direct filtration
2.5-loa
Slow sand or diatoma-
ceous earth filtration
3.0-loa
Alternative filtration tech-
nologies
Determined bv State 2
1 Applies to plants in full compliance with the IESWTR or LT1ESWTR as applicable
2 Credit must be determined through product or site-specific assessment
As discussed previously, studies
indicate that conventional treatment
plants producing very low filtered water
turbidity can achieve a higher level of
Cryptosporidium removal than 3-log,
and today's rule allows such plants to
receive additional treatment credit.
Further, States can award a higher or
lower level of credit to an individual
plant based on a site-specific
demonstration of performance. Section
IV.D provides details on both of these
topics.
The Cryptosporidium removal credits
for filtration plants in today's rule differ
from the amount of credit awarded
under the IESWTR and LTlESWTR. As
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
679
discussed in section III, those rules
require all filtered PWSs to achieve 2-
log removal of Cryptosporidium. PWSs
using conventional treatment, or direct,
slow sand, or diatomaceous earth
filtration are in compliance with this
requirement if they meet specified
filtered water turbidity standards. These
regulatory criteria were based on
consideration of the minimum level of
removal that all these filtration
processes will achieve (USEPA 1998a).
However, in the risk assessments that
supported these regulations, EPA
estimated that most filtration plants will
achieve significantly more removal,
with median Cryptosporidium
reductions near 3-log.
Today's rule will supplement
IESWTR and LTlESWTR requirements
by mandating additional treatment at
certain PWSs based on source-water
Cryptosporidium levels. When assessing
the need for additional treatment at
potentially higher risk PWSs, EPA
believes that considering the full
removal efficiency achieved by different
types of treatment plants is appropriate.
Because making a site-specific
assessment of removal efficiency at all
treatment plants individually is not
feasible, establishing prescribed
treatment credits based on available
data is necessary. Accordingly, EPA has
concluded that available data support
the higher levels of prescribed credit
towards Cryptosporidium treatment
requirements for filtration plants
established by today's rule.
What is the appropriate statistical
measure for classifying PWSs into
treatment bins?
EPA and the Advisory Committee
evaluated different statistical measures
for characterizing Cryptosporidium
monitoring results to determine if
additional treatment should be required.
These measures included the arithmetic
mean, median, 90th percentile, and
maximum.
EPA concluded, consistent with
Advisory Committee recommendations,
that Cryptosporidium levels should be
characterized by an arithmetic mean.
This conclusion is based on two factors:
(1) Available data suggest that the mean
concentration directly relates to the
average risk of the exposed population
(i.e., drinking water consumers); and (2)
with a limited number of samples, the
mean can be estimated more accurately
than other statistical measures, such as
a 90th percentile estimate.
What degree of additional treatment is
needed for higher source water
Cryptosporidium levels?
Development of the risk-based
treatment requirements in today's rule
involved first determining the threshold
source-water Cryptosporidium level at
which filtered PWSs should provide
additional treatment to protect public
health. The key factors in making this
determination were the estimations of
Cryptosporidium risk and treatment
plant removal efficiency discussed
previously, along with the performance
of analytical methods for classifying
PWSs in different treatment bins.
EPA and Advisory Committee
deliberations focused on mean source-
water Cryptosporidium concentrations
in the range of 0.01 to 0.1 oocysts/L as
threshold levels for requiring additional
treatment. Based on the type of risk
information shown in Figure IV.B-1,
these levels are estimated to result in an
annual infection risk in the range of 1.7
x 10-4to6.0 x 10-Mor 1.7 to 60
infections per 10,000 consumers) for a
treatment plant achieving 3-log
Cryptosporidium removal (the treatment
efficiency estimated for conventional
plants under existing regulations).
A shortcoming with establishing the
threshold for additional treatment at
0.01 oocysts/L, however, is that a PWS
would exceed this concentration with
only a very few oocysts being detected.
For a PWS collecting monthly 10-L
samples and bin classification based on
the maximum running annual average,
as required under today's rule, detecting
two oocysts during one year of
monitoring would exceed a mean of
0.01 oocysts/L. Given the uncertainty '
associated with Cryptosporidium
monitoring, EPA and the Advisory
Committee did not support requiring
additional treatment for filtered PWSs
based on so few counts. Although this
shortcoming could theoretically be
addressed by a higher sampling
frequency, the feasibility of increased
sampling is limited by the capacity of
laboratories and the cost of sample
analysis.
A related concern in establishing the
threshold concentration for requiring
additional treatment was bin
misclassification. If the threshold
concentration was set at 0.1 oocysts/L,
for example, some PWSs with actual
mean source-water concentrations
greater than this level would measure a
concentration less than this level and
would be misclassified in the bin that
requires no additional treatment.
Consequently, they would not provide
sufficient public health protection. As
discussed previously, this type of error
is due to the limited number and
volume of samples that can be analyzed,
imperfect method recovery, and
variability in Cryptosporidium
occurrence.
Based on these considerations, the
Advisory Committee recommended and
today's rule establishes that filtered
PWSs must provide additional
treatment for Cryptosporidium w7hen
their mean source-water concentration
exceeds 0.075 oocysts/L. At this
concentration, PWSs collecting monthly
10-L samples must count at least nine
oocysts in one year (9 oocysts per 120
L total sample volume) before additional
treatment is required. Further, any PWS
with a mean source-water infectious
Cryptosporidium level above 0.1
oocysts/L, which corresponds to an
estimated infection risk range of 1.7 to
6.0 x 10 -?, is highly likely to be
appropriately classified in a bin
requiring additional treatment.
After identifying this first threshold
for requiring additional treatment,
determining the Cryptosporidium
concentrations that should bound
higher treatment bins was necessary. In
making these determinations, EPA
concurred with Advisory Committee
recommendations that sought to balance
the possibility of bin misclassification
against equitable risk reduction and
public health protection.
Treatment bins that span a wider
concentration range result in lower bin
misclassification rates. The analysis
summarized in section IV.A shows that
the monitoring required under today's
rule can accurately characterize a PWS's
mean Cryptosporidium level within a
0.5-log margin, but error rates increase
for smaller margins (USEPA 2005a).
Conversely, treatment bins that span a
narrower concentration range provide
more equitable protection from risk
among different PWSs. This is due to
identical treatment requirements
applying to all PWSs in the same bin.
In consideration of these issues, today's
rule establishes two higher treatment
bins at Cryptosporidium concentrations
of 1.0 oocysts/L and 3.0 oocysts/L.
These values result in the four bins
shown in Table IV.B-1. Available
occurrence data indicate that few PWSs
will measure mean Cryptosporidium
concentrations greater than 3.0 oocysts/
L, so there is no need to establish a
treatment bin above this level.
With respect to the degree of
additional Cryptosporidium treatment
that PWSs in Bins 2-4 must provide,
EPA and the Advisory Committee
considered values of 0.5-log and greater.
Today's rule establishes a 1-log
additional treatment requirement for
conventional plants in Bin 2. Because
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the concentration range of Bin 2 spans
approximately one order of magnitude,
this degree of treatment ensures that
plants classified in Bin 2 will achieve
treated water Cryptosporidium levels
comparable to plants in Bin 1.
Conventional plants in Bins 3 and 4
must provide 2.0- and 2.5-log of
additional treatment, respectively. As
recommended by the Advisory
Committee, these higher additional
treatment levels are required based on
the recognition that plants in Bins 3 and
4 have a much greater potential
vulnerability to Cryptosporidium.
Consequently, significantly higher
treatment is appropriate to protect
public health.
These additional treatment
requirements for conventional treatment
plants in Bins 2-4 are based on a
prescribed 3-log Cryptosporidium
treatment credit for compliance with the
IESWTR or LT1ESWTR. as discussed
previously. They translate to total
Cryptosporidium treatment
requirements of 4.0-, 5.0-, and 5.5-log
for Bins 2,3, and 4, respectively. Plants
receiving higher or lower levels of
prescribed treatment credit are required
to provide less or more additional
treatment if classified in Bins 2-4.
Plants using slow sand or
diatomaceous earth filtration, which
also receive a 3-log treatment credit.
incur the same additional treatment
requirements as conventional plants if
classified in Bins 2-4. Direct filtration
plants, however, must provide 0.5-log
greater additional treatment if classified
in Bins 2-4 because they receive a 2.5-
log prescribed credit. EPA expects,
though, that most direct filtration plants
will be classified in Bin 1 because direct
filtration is typically applied only to
higher quality source waters.
Because EPA is unable to establish a
prescribed treatment credit for other
types of filtration technologies like
membranes, bag filters, and cartridge
filters, today's rule requires that States
assign a treatment credit to a particular
filtration product. This credit then
determines the amount of additional
treatment that a plant using this product
must provide if classified in Bins 2—4 in
order to achieve the required total
treatment level. Section IV.D provides
criteria for assigning Cryptosporidium
treatment credit to membranes, bag
filters, and cartridge filters.
As described in Section IV.D, today's
rule establishes a wide range of
treatment and control options through
the microbial toolbox for PWSs to meet
additional Cryptosporidium treatment
requirements. PWSs may choose any
option or combination of options from
the microbial toolbox to meet the
treatment requirements of plants in Bin
2. For plants in Bins 3 or 4, though,
PWSs must achieve at least 1-log of the
additional treatment requirement using
UV, ozone, chlorine dioxide,
membranes, bag filters, cartridge filters,
or bank filtration. EPA is establishing
this provision in today's rule as
recommended by the Advisory
Committee because these processes will
serve as significant additional treatment
barriers for PWSs with the highest levels
of pathogens in their sources.
How should PWSs calculate their
treatment bin classification?
The specific calculations that PWSs
use to determine their bin classification
are based on analyses of
misclassification rates and bias. As
described in section IV.A, today's rule
requires PWSs to collect at least 24
samples (except for plants that operate
only part-year) when they monitor for
Cryptosporidium. Most PWSs will
collect these 24 samples over two years,
but PWSs may sample at a higher
frequency and small PWSs may
complete this monitoring in one year.
These differences affect the bin
classification calculation.
PWSs that sample monthly over two
years (24 samples total) must use the
maximum running annual average
(Max-RAA) for bin classification
because this achieves a low false
negative rate (the likelihood a PWS will
be incorrectly classified in a lower bin).
In comparison, if such PWSs used the
mean of all samples over two years tor
bin classification, the false negative rate
would be almost four times higher (see
Table IV.B.4).
PWSs that choose to sample at least
twice per month over two years (48
samples total) must use the mean of all
48 samples for their bin classification.
This approach achieves a low false
negative rate similar to the Max-RAA for
24 samples and, in addition, reduces the
false positive rate (the likelihood a PWS
will be incorrectly classified in higher
bin—see Table IV.B.4). Due to the lower
false positive rate associated with 48
samples, EPA expects that some PWSs
will choose to sample for
Cryptosporidium twice per month.
Small PWSs (serving fewer than
10,000 people) that complete their
Cryptosporidium monitoring over one
year must use the mean of all 24
samples for bin classification. This
approach has a higher false negative rate
than the approaches allowed for PWSs
that monitor over two years. However,
it is the only feasible option for PWSs
that conduct just one year of
Cryptosporidium sampling. Averaging
sample concentrations over less than
one year is not appropriate (except in
the case of plants that operate only part-
year that monitor for less than one year)
as this would bias the bin classification
due to seasonal variation in water
quality.
TABLE IV.B-4.—FALSE POSITIVE AND
FALSE NEGATIVE RATES FOR MONI-
TORING AND BINNING STRATEGIES
CONSIDERED FOR THE LT2ESWTR
Strategy
48 sample arith-
metic mean
24 sample Max-
RAA
24 sample arith-
metic mean ...
False
positive '
1 .7%
5.3%
2.8%
False
negative 2
1 4%
1 7%
6.2%
1 False positive rates calculated for systems
with Cryptosporidium concentrations 0.5 log
below the Bin 1 boundary of 0 075 oocysts/L
2 False negative rates calculated for systems
with Cryptosporidium concentrations 0.5 log
above the Bin 1 boundary of 0.075 oocysts/L.
Two additional considerations that
relate to characterizing Cryptosporidium
monitoring results to determine
treatment requirements are (1) fewer
than 100 percent of oocysts in a sample
are recovered and counted by the
analyst and (2) not all the oocysts
measured with Methods 1622 or 1623
are capable of causing infection. These
two factors are offsetting, in that oocyst
counts not adjusted for recovery tend to
underestimate the true concentration,
while the total oocyst count typically
overestimates the infectious
concentration that presents a health
risk.
As described in section III, matrix
spike data indicate that average recovery
of Cryptosporidium oocysts with
Methods 1622 or 1623 in a national
monitoring program will be
approximately 40 percent. Regarding the
fraction of oocysts that are infectious,
LeChevallier et al. (2003) tested natural
waters for Cryptosporidium using both
Method 1623 and a method (cell
culture-PCR) to test for infectivity.
Results suggested that 37 percent of the
Cryptosporidium oocysts detected by
Method 1623 were infectious. This
finding is consistent with the
observation that 37 percent of the
oocysts counted during the ICRSS using
Methods 1622 or 1623 had internal
structures, which indicate a higher
likelihood of infectivity (among the
remaining oocysts, 47 percent had
amorphous structures and 16 percent
were empty).
While it is not possible to establish a
precise value for method recovery or the
fraction of oocysts that are infectious,
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681
available data suggest that these
parameters may be of similar
magnitude. Consequently, the Advisory
Committee recommended that
monitoring results should not be
adjusted to account for either recovery
or the fraction infectious. EPA concurs
with this recommendation and today's
rule requires that PWSs be classified in
treatment bins using the total number of
Cryptosporidium oocysts counted,
without further adjustment. The
LT2ESWTR treatment bins in today's
rule are constructed to reflect this
approach.
3. Summary of Major Comments
For filtered PWS treatment
requirements in the LT2ESWTR
proposal, EPA received significant
public comment on the risk-based
approach to requiring additional
treatment, the role of States in
determining bin classification, and the
treatment credit for filtration plants. The
following discussion summarizes
comments in these areas and EPA's
responses.
Most commenters supported the risk-
based approach of the LT2ESWTR in
which filtered PWSs monitor for
microbial contaminants and only those
PWSs finding higher levels of
contamination are required to provide
additional treatment for
Cryptosporidium. Among these
comments, many stated support for the
four treatment bins for filtered PWSs,
with some noting that future research
will indicate whether the bins should be
restructured in a later rulemaking.
Several commenters expressed support
for EPA's combination of the Stage 2
DBPR and LT2ESWTR as essential to
creating a balanced approach between
DBF control and microbial risk.
A few commenters opposed the
expenditure of funds to reduce risk from
Cryptosporidium on the basis that
epidemiological evidence suggests this
risk is low and most communities have
not experienced cryptosporidiosis
outbreaks. EPA agrees that additional
treatment for Cryptosporidium in
drinking water is not warranted in all
communities. Under today's rule, most
PWSs are expected to be classified in
the lowest bin, which requires no
additional treatment. However, based on
risk information presented in USEPA
(2005a) and summarized in this
preamble, EPA believes that additional
treatment is necessary to protect public
health in PWSs with the highest
Cryptosporidium levels. Further, as
described in USEPA (2005a), EPA's
assessment of Cryptosporidium risk in
drinking water is consistent with the
limited available epidemiological data
on disease incidence.
With respect to the role of States in
bin classification, most commenters
recommended that States assign or
approve the bin classification for their
PWSs. Commenters maintained that
State approval of bin classification is an
inherent governmental function and
will avoid confusion as to the level of
treatment each PWS must provide.
Further, the approval process will
provide an opportunity for dialog
between States and PWSs. EPA agrees
with these comments and today's rule
requires PWSs to submit their
calculation of bin classification to the
State for review. If the PWS does not
hear back from the State, it must
proceed to apply the level of treatment
appropriate for its calculated bin
classification in accordance with its
applicable compliance schedule.
In regard to the Cryptosporidium
treatment credit that should be awarded
to filtration plants, many commenters
supported the 3-log Cryptosporidium
removal credit for conventional
treatment and slow sand filtration.
Some comments included data showing
that conventional treatment can achieve
greater than 4-log removal of
Cryptosporidium, and several
commenters stated concerns that EPA
has underestimated the level of
treatment achievable through
conventional treatment. Commenters
supported the inclusion of plants using
softening and dissolved air flotation for
conventional treatment credit and
requested that EPA extend this credit to
similar treatment trains using other
types of clarification processes.
EPA recognizes that studies show
conventional treatment can achieve
more than 3-log Cryptosporidium
removal under optimal conditions.
However, studies also demonstrate that
removal efficiencies can be significantly
less for suboptimal plant set-up and
operation. EPA does not expect that all
plants will operate under optimal
conditions at all times. Consequently,
today's rule awards a prescribed 3-log
credit to conventional plants complying
with the IESWTR or LTlESWTR and
allows plants to receive higher credit
through demonstrating low finished
water turbidity or through an alternative
demonstration of performance, as
describe in section IV.D. EPA agrees that
plants using alternative clarification
process that involves solids removal
between coagulation and filtration
should qualify for 3-log credit and
today's rule provides for this.
C. Unfiltered System Cryptosporidium
Treatment Requirements
I. Today's Rule
Today's rule requires all PWSs that
use a surface water or GWUDI source
and are unfiltered to provide treatment
for Cryptosporidium. The degree of
required treatment depends on the level
of Cryptosporidium in the source water,
as determined through required
monitoring. Further, unfiltered PWSs
must meet overall treatment
requirements using at least two
disinfectants and must continue to meet
all applicable filtration avoidance
criteria. Details of these requirements
follow.
a. Determination of mean
Cryptosporidium level. Following
completion of the required initial source
water monitoring described in section
IV.A, each unfiltered PWS must
determine the arithmetic mean of all its
Cryptosporidium sample results
generated during the monitoring period.
As required for filtered PWSs,
individual sample results must be
calculated as the total number of oocysts
counted, divided by the volume assayed
(see section V.K for details). Samples are
not adjusted for method recovery and,
in samples where no oocysts are
detected, the result is treated as zero.
Unfiltered PWSs must report their
mean Cryptosporidium level to the State
for approval (see section IV.G for
specific reporting dates). The report
must include a summary of the data
used to determine the mean
concentration. If the State does not
respond to a PWS regarding its mean
Cryptosporidium level, the PWS must
comply with the Cryptosporidium
treatment requirements of today's rule,
as described next, based on the reported
level.
If EPA does not amend today's rule
before the second round of monitoring
described in section IV.A, unfiltered
PWSs must recalculate their mean
Cryptosporidium level using results
from the second round of monitoring.
Unfiltered PWSs must report this level
to the State as described for the initial
round of monitoring.
b. Cryptosporidium treatment
requirements. Unfiltered PWSs must
comply with the following treatment
requirements based on their mean
source-water Cryptosporidium level: if
the level is less than or equal to 0.01
oocysts/L then at least 2-log
Cryptosporidium inactivation is
required; if the level is greater than 0.01
oocysts/L, or if the unfiltered PWS
chooses not to monitor for
Cryptosporidium, then at least 3-log
Cryptosporidium inactivation is
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required. See section IV.G for treatment
compliance dates.
EPA has developed criteria, described
in section IV.D, to award
Cryptosporidium inactivation credit for
treatment with chlorine dioxide, ozone,
or UV light. Unfiltered PWSs may use
ariy of these disinfectants to meet their
Cryptosporidium inactivation
requirements under today's rule.
Further, unfiltered PWSs must achieve
the following with respect to
disinfection treatment:
(1) A PWS that uses chlorine dioxide
or ozone and fails to achieve the
required level of Cryptosporidium
inactivation on more than one day in
the calendar month is in violation of the
treatment technique requirement.
(2) A PWS that uses UV light and fails
to achieve the required level of
Cryptosporidium inactivation in at least
95 percent of the water delivered to the
public every month is in violation of the
treatment technique requirement.
c. Use of two disinfectants, Unfiltered
PWSs must use at least two different
disinfectants to provide 4-log virus, 3-
log Giardia lamblia, and 2- or 3-log
Cryptosporidium inactivation as
required under 40 CFR 141.72(a) and
today's rule. Further, each of two
disinfectants must achieve by itself the
total inactivation required for one of
these target pathogens. This requirement
does not modify the existing
requirement under 40 CFR 141.72(a) for
PWSs to provide a disinfectant residual
in the distribution system.
2. Background and Analysis
The intent of the Cryptosporidium
treatment requirements for unfiltered
PWSs in today's final rule is to ensure
that they achieve public health
protection equivalent to that achieved
by filtered PWSs. These requirements
are unchanged from the August 11, 2003
proposal (USEPA 2003a), and they
reflect consensus recommendations by
the Stage 2 M-DBP Advisory Committee
(USEPA 2000a). The following
discussion summarizes the Agency's
basis for establishing risk-targeted
Cryptosporidium treatment
requirements for unfiltered PWSs in
today's rule and for requiring the use of
two disinfectants.
a. Basis for Cryptosporidium
treatment requirements. As described in
section III, available data suggest that
unfiltered PWSs must take additional
steps to achieve public health protection
against Cryptosporidium equivalent to
that provided by filtered PWSs.
In occurrence data from the ICR, the
median Cryptosporidium level in
unfiltered PWS sources was 0.0079
oocysts/L, which is approximately 10
times less than the median level of
0.052 oocysts/L in filtered PWS sources.
In translating these source water levels
to finished water concentrations, EPA
and the Advisory Committee assumed
that conventional filtration treatment
plants in compliance with the IESWTR
or LT1ESWTR achieve an average of 3-
log (99.9 percent) removal of
Cryptosporidium. Existing regulations
do not require unfiltered PWSs to
provide any treatment for
Cryptosporidium.
If the median source water
Cryptosporidium level in filtered PWSs
is approximately 10 times higher than in
unfiltered PWSs, and filtered PWSs
achieve 3-log Cryptosporidium removal,
then the median finished water
Cryptosporidium level in filtered PWSs
is approximately 100 times lower than
in unfiltered PWSs. Thus, these data
suggest that most unfiltered PWSs must
provide 2-log Cryptosporidium
treatment to ensure equivalent public
health protection.
Some unfiltered PWSs must provide
greater than 2-log Cryptosporidium
treatment to ensure equitable protection.
depending on their source water level.
Under today's rule, the
Cryptosporidium treatment
requirements for filtered PWSs. as
described in section IV.B.I, will achieve
mean finished water Cryptosporidium
levels of less than 1 oocyst/10.000 L. An
unfiltered PWS with a mean source
water Cryptosporidium concentration
above 0.01 oocysts/L would have to
provide at least 3-log inactivation to
achieve an equivalent finished water
Cryptosporidium level.
As stated earlier, EPA has determined
that UV light is a feasible technology for
PWSs of all sizes, including unfiltered
PWSs, to inactivate Cryptosporidium. In
addition, treating for Cryptosporidium
using ozone is feasible for some
unfiltered PWSs. Inactivating
Cryptosporidium with chlorine dioxide,
while allowed under today's rule, does
not appear to be feasible for most
unfiltered PWSs due to regulatory limits
on chlorite—a chlorine dioxide
byproduct.
Based on these findings, today's rule
requires all unfiltered PWSs to provide
at least 2-log Cryptosporidium
inactivation, and to provide at least 3-
log inactivation if the mean source
water level exceeds 0.01 oocysts/L.
These treatment requirements will
ensure that unfiltered PWSs achieve
public health protection against
Cryptosporidium that is comparable to
filtered PWSs in the finished water that
is distributed to consumers.
Available data indicate that no
unfiltered PWSs will show measured
mean source water Cryptosporidium
levels of 0.075 oocysts/L or higher—the
level at which a filtered PWS must
provide at least 4-log Cryptosporidium
under today's rule. Consequently, EPA
is not establishing treatment
requirements in today's rule to address
Cryptosporidium at this higher level.
Under existing regulations (40 CFR
141.171 and 141.521), unfiltered PWSs
must maintain a watershed control
program that minimizes the potential for
contamination by Cryptosporidium
oocysts in the source water. If the
measured mean Cryptosporidium level
in an unfiltered PWS is 0.075 oocysts/
L or higher, EPA believes the State
should critically evaluate the adequacy
of the watershed control program,
Under today's rule, unfiltered PWSs
using ozone or chlorine dioxide to treat
for Cryptosporidium must demonstrate
the required 2- or 3-log inactivation
every day the PWS serves water to the
public, except any one day each month.
Existing regulations (40 CFR
141.72(a)(lj) require unfiltered PWSs to
ensure inactivation of 3-log Giardia
lamblia and 4-log viruses every day
except any one day per month.
Consequently, today's rule extends this
compliance standard to
Cryptosporidium inactivation.
For unfiltered PWSs that use UV to
treat for Cryptosporidium, today's rule
requires demonstration of the required
2- or 3-log inactivation in at least 95
percent of the water delivered to the
public every month. EPA intends this
standard to be comparable to the "every
day except any one day per month"
standard established for ozone and
chlorine dioxide. Because UV
disinfection systems will typically
consist of multiple reactors that will be
monitored continuously, EPA believes
that a compliance standard based on the
percentage of water disinfected to the
required level is more appropriate than
a single daily measurement. Section
IV.D describes an equivalent standard
for filtered PWSs.
b. Basis for requiring the use of two
disinfectants. Unfiltered PWSs must use
at least two different disinfectants to
meet the inactivation requirements for
Cryptosporidium (2- or 3-log), Giardia
lamblia (3-log) and viruses (4-log), and
each of two disinfectants must achieve
by itself the total inactivation required
for one of these target pathogens. For
example, a PWS could use UV light to
achieve 3-log inactivation of Giardia
lamblia and Cryptosporidium and use
chlorine to provide 4-log virus
inactivation. The use of two
disinfectants protects public health by
creating multiple barriers against
microbial pathogens. This has two
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683
general advantages over a single barrier:
improved reliability and a broader
spectrum of efficacy.
Because unfiltered PWSs rely solely
on inactivation for microbial treatment,
an unfiltered PWS using only one
disinfectant would provide no primary
microbial treatment if that disinfection
process were to fail. While disinfection
processes should be designed for a high
level of reliability, they are not generally
100 percent reliable. Existing
regulations and today's rule recognize
this limitation by allowing unfiltered
PWSs to fail to achieve required
disinfection levels one day per month.
Consequently, EPA believes that for
effective public health protection,
unfiltered PWSs should use at least two
primary disinfection processes. If one
process fails, a second process will
provide some degree of protection
against pathogens.
A second advantage of a PWS using
multiple disinfectants is that this
approach will typically be more
effective against a broad spectrum of
pathogens. The efficacy of different
disinfectants against different types of
pathogens varies widely. For example,
UV light appears to be very effective for
inactivating protozoa like
Cryptosporidium and Giardia lamblia,
but is less effective against certain
enteric viruses like adenovirus.
Chlorine, however, is highly effective
against enteric viruses but less effective
against protozoa. As a result, multiple
disinfectants will generally provide
more effective inactivation of a wide
range of pathogens than a single
disinfectant.
c. Filtration avoidance. Today's rule
does not withdraw or modify any
existing criteria for avoiding filtration
under 40 CFR 141.71. Accordingly,
unfiltered PWSs must continue to
comply with all existing filtration
avoidance criteria. EPA believes these
criteria help to ensure that watershed
protection provides a microbial barrier
in those PWSs that do not filter.
Further, today's rule does not
establish any new criteria for filtration
avoidance. In the proposed LT2ESWTR,
EPA indicated that compliance with
DBP standards under the Stage 2 DBPR
would be incorporated into the criteria
for filtration avoidance. However, EPA
has not done this in today's final rule in
order to give States more flexibility in
working with unfiltered PWSs to
comply with the Stage 2 DBPR.
3. Summary of Major Comments
EPA received significant public
comment on the following treatment
requirements for unfiltered PWSs in the
LT2ESWTR proposal: the requirement
for all unfiltered PWSs to provide at
least 2-log Cryptosporidium
inactivation, treatment requirements for
unfiltered PWSs with high
Cryptosporidium levels, and the
requirement for unfiltered PWSs to use
at least two disinfectants. A summary of
these comments and EPA's responses
follows.
Several commenters supported the
requirement that all unfiltered PWSs
achieve at least 2-log inactivation of
Cryptosporidium, noting that this was
part of the Agreement in Principle
(USEPA 2000a). Some commenters,
however, requested that EPA not
establish a minimum Cryptosporidium
treatment level due to the following
factors: monitoring of unfiltered PWS
sources has shown very low levels of
Cryptosporidium, and some sources
may have no Cryptosporidium; the
Cryptosporidium in an unfiltered PWS
source are likely to be of non-human
origin and are less likely to infect
humans; and disease incidence data
have not established a link between
unfiltered PWSs and cryptosporidiosis
in consumers.
In response, EPA continues to believe
that all unfiltered PWSs should provide
treatment for Cryptosporidium to
protect public health. Monitoring has
shown that unfiltered PWS sources are
contaminated with Cryptosporidium,
and no source is likely to be entirely
free of Cryptosporidium due to the
ubiquity of Cryptosporidium in both
human and many animal populations.
Studies, such as those cited in section
III, have established that
Cryptosporidium from animals can
infect humans. EPA does not regard the
absence of cryptosporidiosis cases
attributed to drinking water in a
particular community as evidence that
no treatment for Cryptosporidium is
needed. As described in section III,
cryptosporidiosis incidence data
generally do not indicate overall disease
burden because most cases are
undetected, unreported, and not traced
to a particular source.
Some commenters recommended that
EPA require only 1-log Cryptosporidium
inactivation for unfiltered PWSs that
demonstrate source water levels below
0.001 oocysts/L. EPA does not support
this approach, though, due to concerns
with the reliability of monitoring to
establish such an extremely low level of
Cryptosporidium. In addition, UV light
is a feasible technology for unfiltered
PWSs of all sizes to achieve at least 2-
log Cryptosporidium inactivation. For
these reasons, EPA has concluded that
the minimum Cryptosporidium
treatment level should be 2-log, as
recommended by the Advisory
Committee.
In the proposed LT2ESWTR, EPA
requested comment on the treatment
that should be required if an unfiltered
PWS measured a Cryptosporidium level
of 0.075 oocysts/L or higher—the
concentration at which a filtered PWS
must provide at least 4-log treatment.
Several commenters supported
equivalent treatment requirements (i.e.,
at least 4-log reduction) for unfiltered
and filtered PWSs with
Cryptosporidium at this level. Other
commenters stated that available data
indicate no unfiltered PWSs are likely to
measure Cryptosporidium at such a high
level.
EPA agrees that available data on
Cryptosporidium occurrence suggest
that no unfiltered PWSs will measure a
mean level of 0.075 oocysts/L or higher.
Moreover, establishing a 4-log treatment
requirement on the precautionary basis
that an unfi Itered PWS might measure a
high level of Cryptosporidium has a
significant cost—it would require any
unfiltered PWS to provide 4-log, rather
than 3-log, inactivation to avoid
Cryptosporidium monitoring. EPA
expects that many small unfiltered
PWSs will choose to provide 3-log
Cryptosporidium inactivation rather
than monitor for Cryptosporidium.
Accordingly, EPA has concluded that
establishing a 4-log Cryptosporidium
treatment requirement for unfiltered
PWSs that neasure a Cryptosporidium
level of 0.075 oocysts/L or higher is
unnecessary and inappropriate at this
time. In the event that an unfiltered
PWS does measure Cryptosporidium at
this level, the State can require the PWS
to take steps to reduce the
contamination under existing watershed
control program requirements for
unfiltered PWSs.
Some commenters supported the
requirement for unfiltered PWSs to use
at least two disinfectants to meet overall
inactivation requirements for
Cryptosporidium, Giardia lamblia, and
viruses anc: for each disinfectant to
achieve the total inactivation required
for one target pathogen. These
commenters stated that this requirement
will improve inactivation against a wide
variety of pathogens and increase
treatment reliability. Other commenters,
though, opposed this requirement for a
number of reasons: it will unnecessarily
limit the ability of PWSs to minimize
DBPs, there is no similar requirement
for filtered PWSs, the requirement for
each disinfectant to achieve the total
inactivation for one pathogen goes
beyond the Agreement in Principle, and
EPA has not provided a risk analysis to
justify the requirement.
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In response, EPA believes that the
benefits of both redundancy and a broad
spectrum of microbial protection justify
requiring the use of two disinfectants.
Further, requiring each disinfectant to
achieve the full inactivation of one
target pathogen establishes a minimal
performance level so that each
disinfectant will serve as a substantive
barrier. In most cases, PWSs will
comply with this requirement by using
UV or ozone to inactivate Giardia
lamblia and Cryptosporidium and using
chlorine to inactivate viruses.
D. Options for Systems To Meet
Crvptosporidium Treatment
Requirements
I. Microbial Toolbox Overview
Today's rule includes a variety of
treatment and control options,
collectively termed the "microbial
toolbox," that PWSs can implement to
comply with additional
Cryptosporidium treatment
requirements. Options in the microbial
toolbox include source protection and
management programs, prefiltration
processes, treatment performance
programs, additional filtration
components, and inactivation
technologies. The Stage 2 M-DBP
Advisory Committee recommended the
microbial toolbox to provide PWSs with
broad flexibility in selecting cost-
effective LT2ESWTR compliance
strategies.
Most options in the microbial toolbox
carry prescribed credits toward
Cryptosporidium treatment
requirements. PWSs receive these
credits by demonstrating compliance
with required design and operational
criteria, which are described in the
sections that follow. In addition, States
may award treatment credits other than
the prescribed credit through a
"demonstration of performance." which
involves site-specific testing by a PWS
with a State-approved protocol. Under a
demonstration of performance, a State
may award credit to a treatment plant or
to a unit process of a treatment plant
that is higher or lower than the
prescribed credit. This option also
allows States to award credit to a unit
process that does not meet the design
and operational criteria in the microbial
toolbox for prescribed credit.
To be eligible for treatment credit for
a microbial toolbox option, PWSs must
initially report compliance with design
criteria, where required, to the State
(some options do not require design
criteria). Thereafter, for most options,
PWSs must report compliance with
required operational criteria to the State
each month (the watershed control
program option requires yearly
reporting). Failure by a PWS in any
month to demonstrate treatment credit
equal to or greater than its
Cryptosporidium treatment
requirements under today's rule is a
treatment technique violation. This
violation lasts until the PWS
demonstrates that it is meeting criteria
for sufficient treatment credit to satisfy
its Cryptosporidium treatment
requirements.
As described in section IV.B, filtered
PWSs may use any option or
combination of options from the
microbial toolbox to comply with the
additional Crvptosporidium treatment
requirements of Bin 2. PWSs in Bins 3
or 4 must achieve at least 1-log of the
additional Cryptosporidium treatment
requirement by using ozone, chlorine
dioxide, UV, membranes, bag filtration,
cartridge filtration, or bank filtration.
If allowed by the State, PWSs may use
different microbial toolbox options in
different months to comply with
Cryptosporidium treatment
requirements under today's rule. For
example, a PWS in Bin 2, which
requires 1-log additional
Cryptosporidium treatment, could
comply with this requirement in one
month using "individual filter
performance," which carries a 1-log
credit; in a subsequent month, this PWS
could use "combined filter
performance" and "presedimentation
basin with coagulation," which each
carry 0.5-log credit. This approach is
intended to provide greater operational
flexibility to PWSs. It allows a PWS to
receive treatment credit for a microbial
toolbox option in any month the PWS
is able to meet required operational
criteria, even if the PWS does not meet
these criteria during all months of the
year.
Table IV.D-1 summarizes prescribed
treatment credits and associated design
and operational criteria for microbial
toolbox options. The sections that
follow describe each toolbox option in
detail. In addition, EPA has developed
three guidance documents to assist
PWSs with selecting and implementhig
microbial toolbox options: Toolbox
Guidance Manual, UV Disinfection
Guidance Manual, and Membrane
Filtration Guidance Manual. Each may
be acquired from EPA's Safe Drinking
Water Hotline, which can be contacted
as described under FOR FURTHER
INFORMATION CONTACT at the beginning of
this notice.
TABLE IV.D-1.—MICROBIAL TOOLBOX: OPTIONS, CREDITS AND CRITERIA
Toolbox option
Cryptosporidium treatment credit with design and operational criteria1
Source Protection and Management Toolbox Options
Watershed control program
Alternative source/intake manage-
ment.
0.5-log credit for State-approved program comprising required elements, annual program status report to
State, and regular watershed survey Unfiltered PWSs are not eligible for credit
No prescribed credit PWSs may conduct simultaneous monitoring for treatment bin classification at alter-
native intake locations or under alternative intake management strategies
Prefiltration Toolbox Options
Presedimentation basin with coagu-
lation
Two-stage lime softening
Bank filtration
0.5-log credit during any month that presedimentation basins achieve a monthly mean reduction of 0.5-log
or greater in turbidity or alternative State-approved performance criteria To be eligible, basins must be
operated continuously with coagulant addition and all plant flow must pass through basins
0.5-log credit for two-stage softening where chemical addition and hardness precipitation occur in both
stages All plant flow must pass through both stages. Single-stage softening is credited as equivalent to
conventional treatment.
0.5-log credit for 25-foot setback, 1.0-log credit for 50-foot setback, horizontal and vertical wells only, aqui-
fer must be unconsolidated sand containing at least 10 percent fines (as defined in rule); average tur-
bidity in wells must be less than 1 NTU. PWSs using existing wells followed by filtration must monitor
the well effluent to determine bin classification and are not eligible for additional credit.
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TABLE IV.D-1— MICROBIAL TOOLBOX: OPTIONS, CREDITS AND CRITERIA—Continued
Toolbox option
Cryptospondium treatment credit with design and operational criteria'
Treatment Performance Toolbox Options
Combined filter performance ...
Individual filter performance
Demonstration of performance
0.5-log credit for combined filter effluent turbidity less than or equal to 0.15 NTU in at least 95 percent of
measurements each month
0.5-log credit (in addition to 0.5-log combined filter performance credit) if individual filter effluent turbidity is
less than or equal to 0 15 NTU in at least 95 percent of samples each month in each filter and is never
greater than 0 3 NTU in two consecutive measurements in any filter
Credit awarded to unit process or treatment tram based on a demonstration to the State with a State-ap-
proved protocol.
Additional Filtration Toolbox Options
Bag and cartridge filters
Membrane filtration
Second stage filtration ..
Slow sand filters
Up to 2-log credit with demonstration of at least 1-log greater removal in a challenge test when used sin-
gly. Up to 2 5-log credit with demonstration of at least 0.5-log greater removal in a challenge test when
used in series
Log credit equivalent to removal efficiency demonstrated in challenge test for device if supported by direct
integrity testing.
0 5-log credit for second separate granular media filtration stage if treatment train includes coagulation
prior to first filter
2.5-log credit as a secondary filtration step, 3.0-log credit as a primary filtration process No prior
chlonnation.
Inactivation Toolbox Options
Chlorine dioxide
Ozone
UV
Log credit based on measured CT in relation to CT table.
Log credit based on measured CT in relation to CT table.
Log credit based on validated UV dose in relation to UV dose table; reactor validation testing required to
establish UV dose and associated operating conditions.
Table provides summary information only, refer to following preamble and regulatory language for detailed requirements.
2. Watershed Control Program
a. Today's Rule
Filtered PWSs can receive 0.5-log
credit toward Cryptosporidium
treatment requirements under today's
rule for implementing a State-approved
watershed control program designed to
reduce the level of Cryptosporidium. To
be eligible to receive this credit initially,
PWSs must perform the following steps:
• Notify the State of the intent to
develop a new or continue an existing
watershed control program for
Cryptosporidium treatment credit no
later than two years prior to the date the
PWS must comply with additional
Cryptosporidium treatment
requirements under today's rule.
• Submit a proposed watershed
control plan to the State for approval no
later than one year prior to the date the
PWS must comply with additional
Cryptosporidium treatment
requirements under today's rule. The
watershed control plan must contain
these elements:
(I) The designation of an "area of
influence" in the watershed, which is
defined as the area outside of which the
likelihood of Cryptosporidium
contamination affecting the treatment
plant intake is not significant;
(2) The identification of both potential
and actual sources of Cryptosporidium
contamination, including a qualitative
assessment of the relative impact of
these contamination sources on water
quality at the treatment plant intake;
(3) An analysis of control measures
that could mitigate the sources of
Cryptosporidium contamination,
including the relative effectiveness of
control measures in reducing
Cryptosporidium loading to the source
water and their feasibility; and
(4) A statement of goals and specific
actions the PWS will undertake to
reduce source water Cryptosporidium
levels, including a description of how
the actions will contribute to specific
goals, watershed partners and their
roles, resource requirements and
commitments, and a schedule for plan
implementation.
If the State approves the watershed
control plan for Cryptosporidium
treatment credit, PWSs must perform
the following steps to be eligible to
maintain the credit:
• Submit an annual watershed
control program status report to the
State no later than a date specified by
the State. The status report must
describe the following: (1) how the PWS
is implementing the approved
watershed control plan; (2) the
adequacy of the plan to meet its goals;
(3) how the PWS is addressing any
shortcomings in plan implementation;
and (4) any significant changes that
have occurred in the watershed since
the last watershed sanitary survey.
• Notify the State prior to making any
significant changes to the approved
watershed control plan. If any change is
likely to reduce the planned level of
source water protection, the PWS must
include in this notification a statement
of actions that will be taken to mitigate
this effect.
• Perform a watershed sanitary
survey no less frequently than the PWS
must undergo a sanitary survey under
40 CFR 142.16(b)(3)(i), which is every
three to five years, and submit the
survey report to the State for approval.
The State may require a PWS to perform
a watershed sanitary survey at an earlier
date if the State determines that
significant changes may have occurred
in the watershed since the previous
sanitary survey. A person approved by
the State must conduct the watershed
sanitary survey and the survey must
meet applicable State guidelines. The
watershed sanitary survey must
encompass the area of influence as
identified in the State-approved
watershed control plan, assess the
implementation of actions to reduce
source water Cryptosporidium levels,
and identify any significant new sources
of Cryptosporidium.
PWSs are eligible to receive
Cryptosporidium treatment credit under
today's rule for preexisting watershed
control programs (e.g., programs in
place at the time of rule promulgation).
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To be eligible for credit, such programs
must meet the requirements stated in
this section and the watershed control
plan must address future actions that
will further reduce source water
Cryptosporidium levels.
If the State determines that a PWS is
not implementing the approved
watershed control plan (i.e., the PWS is
not carrying out the actions on the
schedule in the approved plan), the
State may revoke the Cryptosporidium
treatment credit for the watershed
control program. Failure by a PWS to
demonstrate treatment credit at least
equal to its Cryptosporidium treatment
requirement under today's rule due to
such a revocation of credit is a treatment
technique violation. The violation lasts
until the State determines that the PWS
is implementing an approved watershed
control plan or is otherwise achieving
the required level of Cryptosporidium
treatment credit.
PWSs must make the approved
watershed control plan, annual status
reports, and watershed sanitary surveys
available to the public; upon request.
These documents must be in a plain
language style and include criteria by
which to evaluate the success of the
program in achieving plan goals. If
approved by the State, the PWS may
withhold portions of these documents
based on security considerations.
Unfiltered PVVSs are not eligible to
receive Cryptosporidium treatment
credit for a watershed control program
under today's rule. Under existing
regulations (40 CFR 141.71), unfiltered
PWSs must maintain a watershed
control program that minimizes the
potential for contamination by
Cryptosporidium as a condition for
avoiding filtration.
b. Background and Analysis
Cryptosporidium enters drinking
water through fecal contamination of
PWS source waters. Implementing a
watershed control program that reduces
or treats sources of fecal contamination
in PWS sources will benefit public
health by lowering the exposure of
drinking water consumers to
Cryptosporidium and other pathogenic
microorganisms. In addition, a
watershed control program may
enhance treatment plant management
practices through generating knowledge
of the sources, fate, and transport of
pathogens.
The Stage 2 M-DBP Advisory
Committee recommended 0.5-log
Cryptosporidium treatment credit for a
watershed control program (USEPA
2000a), and the August 11, 2003
proposal included criteria for PWSs to
receive this credit (USEPA 2003a). The
following discussion summarizes the
basis for this credit and for differences
in associated requirements between the
proposal and today's final rule.
The efficacy of a watershed control
program in reducing levels of
Cryptosporidium and other microbial'
pathogens depends on the ability of a
PWS to identify and control sources of
fecal contamination. The fecal sources
that are significant in a particular
watershed and the control measures that
will be effective in mitigating these
sources are site specific. Consequently,
EPA believes that States should
determine whether a watershed control
program developed by a PWS to reduce
Crvptosporidium contamination
warrants 0.5-log treatment credit.
Accordingly, today's rule requires State
approval of watershed control programs
for PWSs to receive credit.
If a PWS intends to implement a
watershed control program to comply
with Cryptosporidium treatment
requirements under today's rule, EPA
believes the PWS should notify the State
at least two years prior to the required
treatment compliance date. This
notification will give the State an
opportunity to communicate with the
PWS regarding site-specific
considerations for a watershed control
program. Further, the PWS should
submit the proposed watershed control
plan to the State for approval at least
one year prior to the treatment
compliance date. This schedule will
give the State time to evaluate the
program for approval and, if necessary,
allow the PWS to make modifications
necessary for approval. Thus, today's
rule establishes these reporting
deadlines.
The required elements for a watershed
control plan in today's rule are the
minimum necessary for a program that
will be effective in reducing levels of
Cryptosporidium and other pathogens
in a treatment plant intake. These
elements include defining the area of
the watershed where contamination can
affect the intake water quality,
identifying sources of contamination
within this area, evaluating control
measures to reduce contamination, and
developing an action plan to implement
specific control measures.
EPA encourages PWSs to leverage
other Federal, State, and local programs
in developing the elements of their
watershed control plans. For example,
SDWA section 1453 requires States to
carry out a source water assessment
program (SWAP) for PWSs. Depending
on how a State implements this
program, the SWAP may be used to
define the area of influence in the
watershed and identify actual and
potential contamination sources. In
2002, EPA launched the Watershed
Initiative (67 FR 36172, May 23, 2002)
(USEPA 2002b), which will provide
grants to support watershed-based
approaches to preventing, reducing, and
eliminating water pollution. In addition,
EPA recently promulgated regulations
for Concentrated Animal Feeding
Operations that will limit discharges
that contribute microbial pathogens to
watersheds.
Many PWSs do not control the
watersheds of their sources of supply.
Their watershed control plans should
involve partnerships with watershed
landowners and government agencies
that have authority over activities in the
watershed that mav contribute
Cryptosporidium to the water supply.
Stakeholders that control activities that
could contribute to Cryptosporidium
contamination include municipal
government and private operators of
wastewater treatment plants, livestock
farmers and persons who spread
manure, individuals with failing septic
systems, logging operations, and other
government and commercial
organizations.
After a State approves a watershed
control plan for a PWS and initially
awards 0.5-log Cryptosporidium
treatment credit, the PWS must submit
a watershed control program status
report to the State each year. These
reports are required for States to
exercise oversight and ensure that PWSs
implement the approved watershed
control plan. They also provide a
mechanism for PWSs to work with the
States to address any shortcomings or
necessary modifications in watershed
control plans that are identified after
plan approval.
In addition, PWSs must undergo
watershed sanitary surveys every three
to five years by a State-approved party.
These surveys will provide information
to PWSs and States regarding significant
changes in the watershed that may
warrant modification of the approved
watershed control plan. Also, they allow
for an assessment of watershed control
plan implementation.
The proposed rule required watershed
sanitary surveys annually, but EPA has
reduced the frequency to every three to
five years in today's final rule. This
frequency is consistent with existing
requirements for PWS sanitary surveys.
EPA is establishing this longer
frequency on the basis that most
watersheds will not undergo significant
changes over the course of a single year.
If significant changes in the watershed
do occur, however, PWSs must identify
these changes in their annual program
status reports. In addition, States have
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687
the authority to require that a watershed
sanitary survey be conducted at an
earlier date if the State determines that
significant changes may have occurred
in the watershed since the previous
survey.
In trie proposed rule, approval of a
watershed control program expired after
a PWS completed the second round of
source water monitoring, and the PWS
had to reapply for program approval.
Today's final rule, however, does not
include this requirement. Instead,
today's rule gives States authority to
revoke Cryptosporidium treatment
credit for a watershed control program
at any point if a State determines that
a PWS is not implementing the
approved watershed control plan. EPA
believes this approach is preferable to
the automatic expiration of credit in the
proposed rule for two reasons: (1) It
assures PWSs that if they implement the
approved watershed control plan, they
will maintain the treatment credit; and
(2) it gives States the authority to ensure
PWSs implement watershed control
programs for which they receive
treatment credit and to take action at
any time if a PWS does not.
EPA believes that PWSs should be
eligible to receive Cryptosporidium
treatment credit for watershed control
programs that are in place prior to the
treatment compliance date. The same
requirements for watershed control
program treatment credit apply
regardless of whether the program is
new or existing at the time the PWS
submits the watershed control plan for
approval. In the case of existing
programs, the watershed control plan
must list future activities the PWS will
undertake that will reduce source water
contamination.
The Toolbox Guidance Manual lists
programmatic resources and guidance
available to assist PWSs in building
partnerships and implementing
watershed protection activities. It also
incorporates information on the
effectiveness of different control
measures to reduce Cryptosporidium
levels and provides case studies of
watershed control programs. This
guidance is intended to assist both
PWSs in developing watershed control
programs and States in assessing and
approving these programs.
In addition to this guidance and other
technical resources, EPA provides
funding for watershed and source water
protection -through the Drinking Water
State Revolving Fund (DWSRF) and
Clean Water State Revolving Fund
{DWSRF). Under the DWSRF program,
States may fund source water protection
activities by PWSs, including watershed
management and pathogen source
reduction plans. CWSRF funds can be
used for agricultural best management
practices to reduce pathogen loading in
receiving waters and for the
replacement of failing septic systems.
c. Summary of Major Comments
Public comments on the August 11,
2003, LT2ESWTR proposal supported
the concept of awarding credit towards
Cryptosporidium treatment
requirements for an effective watershed
control program. Commenters expressed
concerns, however, with specific criteria
for awarding this credit, including
annual watershed sanitary surveys, re-
approval of watershed control programs,
standards for existing watershed control
programs, and public availability of
documents related to the watershed
control program. A summary of these
comments and EPA's responses follows.
Regarding the proposed requirement
for annual watershed sanitary surveys,
commenters stated that this frequency is
too high because activities to reduce
Cryptosporidium contamination in the
watershed will often take many years to
implement. These commenters
recommended that watershed sanitary
surveys be performed every three to five
years in conjunction with PWSs sanitary
surveys or longer. In contrast, other
commenters supported annual
watershed sanitary surveys as being
necessary to allow proper responses to
new sources of contamination that can
occur quickly in watersheds. Such
sources can occur through development,
new recreation programs, fires,
unauthorized activities, and other
factors.
While EPA believes that regular
watershed sanitary surveys are
necessary to identify new sources of
contamination and allow States to
properly oversee watershed control
programs, EPA agrees that significant
changes typically will not occur over
one year. Therefore, today's final rule
requires PWSs that receive
Cryptosporidium treatment credit for a
watershed control program to undergo
watershed sanitary surveys every three
to five years, rather than every year. To
address the concern that new sources of
watershed contamination can arise
quickly, today's rule requires PWSs to
identify any significant changes that
have occurred in their watersheds in
their annual program status reports.
States can then require a watershed
sanitary survey at an earlier date if
significant changes have occurred since
the previous survey.
Many commenters opposed the
proposed requirement for PWSs to
reapply for approval of their watershed
control programs after completing the
second round of source water
monitoring. The concern was that this
requirement would discourage PWSs
from pursuing watershed control
programs because they would be
uncertain about whether they would
continue to receive treatment credit for
their programs in the future. As an
alternative, commenters recommended
that States monitor the progress of PWSs
in implementing watershed control
programs through the watershed
sanitary surveys and annual status
reports. A State could then deny
treatment credit to a PWS if it failed to
demonstrate adequate commitment to
its approved watershed control plan.
EPA agrees with these comments and
today's final rule does not include a
requirement for re-approval of the
watershed control program after the
second round of monitoring. Instead,
PWSs must submit annual program
status reports to the State and undergo
regular watershed sanitary surveys. If
the State determines that a PWS is not
implementing its approved watershed
control plan on the basis of these
measures, it can withdraw the treatment
credit associated with the program.
PWSs that implement their approved
watershed control plans, however, can
maintain the associated treatment credit
indefinitely under today's rule.
Several commenters stated that PWSs
with existing watershed control
programs should be eligible for
Cryptosporidium treatment credit under
the same standards that apply to new
programs. EPA agrees that both existing
and new watershed control programs
should be eligible for Cryptosporidium
treatment credit under the same
standards, and today's rule allows this.
As is required for new programs, PWSs
with existing watershed control
programs must submit a watershed
control plan that details future activities
the PWS will implement to reduce
source water contamination. As with
new programs, States will have the
discretion to approve the proposed
watershed control plan for 0.5-log
Cryptosporidium treatment credit.
With respect to a proposed
requirement that the watershed control
plan, annual status reports, and
watershed sanitary surveys be made
available to the public, commenters
stated that homeland security concerns
are associated with these documents.
Homeland security concerns apply to
information on the location of treatment
plant intakes and other structures. EPA
agrees that there are security concerns
associated with watershed control
program documents. EPA also believes,
though, that the public should be
allowed to learn about the actions PWSs
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plan to take to address Cryptosporidium
contamination and the progress of PWSs
in implementing these actions.
Consequently, today's rule requires
PWSs to make the approved watershed
control plan, annual status reports, and
watershed sanitary surveys available to
the public. However, PWSs may
withhold portions of these documents
that raise security concerns with State
approval.
3. Alternative Source
a. Today's Rule
If approved by the State, a PWS may
determine its Cryptosporidium
treatment requirements under today's
rule using additional source water
monitoring results for an alternative
treatment plant intake location or an
alternative intake operational strategy.
By meeting the requirements of this
option, which are described as follows,
a PWS may reduce its Cryptosporidium
treatment requirements under today's
rule.
• Monitoring for an alternative intake
location or operational strategy, termed
"alternative source monitoring," may
only be performed in addition to
monitoring the existing plant intake(s)
(i.e., the intake(s) the PWS uses when it
must begin monitoring under today's
rule).
• Alternative source monitoring must
meet the sample number, sample
frequency, and data quality
requirements that apply to source water
monitoring for bin classification, as
described in section IV.A.
• PWSs that perform alternative
source monitoring must complete this
monitoring by the applicable deadline
for treatment bin classification under
today's rule, as described in section
IV.G. Unless a PWS grandfathers
monitoring data for the existing plant
intake, alternative source monitoring
must be performed concurrently with
monitoring the existing intake.
• PWSs must submit the results of
alternative source monitoring to the
State, along with supporting
information documenting the location
and/or operating conditions under
which the alternative source monitoring
was conducted. If a PWS fulfills these
requirements, the PWS may request that
the State classify the PWS in a treatment
bin under today's rule using the
alternative source monitoring results.
• If the State approves bin
classification for a PWS using
alternative source monitoring results,
the PWS must relocate the plant intake
or implement the intake operational
strategy to reflect the alternative source
monitoring. The PWS must complete
these actions no later than the
applicable date for the PWS to comply
with Cryptosporidium treatment
requirements under today's rule. The
State may specify reporting
requirements to verify operational
practices.
Failure by a PWS that is classified in
a treatment bin using alternative source
monitoring to relocate the intake or
implement the new intake operational
strategy, as required, by the applicable
treatment compliance deadline is a
treatment technique violation. This
violation lasts until the State determines
that the PWS has carried out required
changes to the intake location or
operation or is providing the level of
Cryptosporidium treatment required for
the existing intake location and
operation.
b. Background and Analysis
Plant intake refers to the works or
structures at the head of a conduit
through which water is diverted from a
source (e.g., river or lake) into a
treatment plant. Plants may be able to
reduce influent Cryptosporidium levels
by changing the intake placement
(either within the same source or to an
alternate source) or managing the timing
or level of withdrawal.
The Stage 2 M-DBP Advisory
Committee recommended that PWSs be
allowed to modify their plant intakes to
comply with today's rule, and the
August 11, 2003 proposal included this
option (USEPA 2000a). The
requirements for this option in today's
final rule are unchanged from the
proposal. The following discussion
summarizes the basis for these
requirements.
The effect of changing the location or
operation of a plant intake on influent
Cryptosporidium levels can only be
ascertained through monitoring.
Consequently, EPA is not establishing a
prescriptive credit for this option.
Rather, if a PWS expects that
Cryptosporidium levels from a current
plant intake will result in a bin
classification requiring additional
treatment under today's rule, the PWS
may conduct additional
Crvptosporidium monitoring reflecting a
different intake location or operational
strategy (alternative source monitoring).
The PWS may then request that the
State approve bin classification for the
plant based on alternative source
monitoring results, provided the PWS
will implement the corresponding
changes to the intake location or
operation.
PWSs that conduct alternative source
monitoring must also monitor their
existing plant intakes. Monitoring the
existing intake is required for the State
to determine a treatment bin
classification for a plant in the event the
PWS does not modify the intake (to
reflect alternative source monitoring)
prior to the treatment compliance
deadline under today's rule.
Further, PWSs must conduct
alternative source monitoring within the
applicable time frame for source water
monitoring under today's rule. This
approach is required for the State to
determine a bin classification for the
plant based on alternative source
monitoring by the bin classification
deadline. In addition, this timing will
allow the PWS to modify the intake or
implement additional treatment, if
necessary, by the treatment compliance
deadline. This requirement means,
however, that unless a PWS meets the
requirement for monitoring its existing
intake through grandfathering, the PWS
must perform alternative source
monitoring concurrently with existing
intake monitoring, although it does not
have to be on exactly the same schedule.
Because alternative source monitoring
will be used for bin classification, this
monitoring must comply with all
applicable requirements for source
water monitoring that are described in
section IV.A. Further, the PWS must
provide the State with supporting
information documenting the
conditions, such as the source location.
under which the alternative source
monitoring was conducted. This
documentation is required so that if bin
classification is based on alternative
source monitoring results, the State can
ensure the PWS implements the
corresponding modifications to the
intake.
c. Summary of Major Comments
Public comments on the August 11,
2003, LT2ESWTR proposal supported
allowing PWSs to determine treatment
bin classification by monitoring for an
alternative intake location or
operational strategy. Several
commenters stated they were unsure if
this option would be widely used due
to the burden of performing
Cryptosporidium monitoring at both the
current intake and the alternative
source. Commenters also recommended
that PWSs first conduct source water
assessments or watershed sanitary
surveys to evaluate intake management
strategies to reduce Cryptosporidium
levels in the plant influent.
In response, EPA believes that PWSs
who choose alternative source
monitoring must also monitor their
current intake so that the State can
determine the appropriate bin
classification if the PWS does not
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689
subsequently modify its intake. While
few PWSs may choose to pursue
alternative source monitoring, EPA
believes this option should be available
for PWSs that elect to do so. EPA agrees
that it is appropriate for PWSs to assess
contamination sources in the watershed
when considering whether to relocate or
change the operation of their intakes.
The Toolbox Guidance Manual provides
direction to PWSs on conducting these
assessments.
EPA requested comment on whether
representative Cryptosporidium
monitoring can be performed prior to
implementation of a new intake strategy
(e.g., monitoring a new source prior to
constructing a new intake structure).
Commenters stated that there may be
situations where allowing
Cryptosporidium monitoring to
demonstrate a reduction in oocyst levels
prior to implementation of a new intake
strategy is appropriate. Incurring costs
for constructing a new intake before
determining whether the strategy will
reduce oocyst levels is not cost effective.
EPA agrees with this comment and
today's rule allows PWSs to conduct
alternative source monitoring prior to
constructing a new intake and to base
their bin classification on these
monitoring results with State approval.
4. Pre-Sedimentation With Coagulant
a. Today's Rule
Presedimentation is a preliminary
treatment process used to remove
gravel, sand and other particulate
material from the source water through
settling before the water enters the
primary clarification and filtration
processes in a treatment plant. PWSs
receive 0.5-log credit towards
Cryptosporidium treatment
requirements under today's rule for a
presedimentation process that meets the
following conditions:
• Treats all flow reaching the
treatment plant;
• Continuously adds a coagulant to
the presedimentation basin;
• Achieves one of the following two
performance criteria:
(1) Demonstrates at least 0.5-log mean
reduction of influent turbidity. This
reduction must be determined using
daily turbidity measurements in the
presedimentation process influent and
effluent and must be calculated as
follows: logio (monthly mean of daily
influent turbidity)—logio (monthly
mean of daily effluent turbidity).
(2) Complies with State-approved
performance criteria that demonstrate at
least 0.5-log mean removal of micron-
sized particulate material, such as
aerobic spores, through the
presedimentation process.
PWSs may receive treatment credit for
a presedimentation process during any
month the process meets these
conditions. To be eligible for credit,
PWSs must report compliance with
these conditions to the State each
month. PWSs may earn
presedimentation treatment credit for
only part of the year if the process does
not meet these conditions year-round. In
this situation, PWSs must fully meet
their Cryptosporidium treatment
requirements under today's rule using
other microbial toolbox options during
those months when the PWS does not
receive treatment credit for
presedimentation.
Alternatively, PWSs may apply to the
State for Cryptosporidium treatment
credit for presedimentation processes
using a demonstration of performance,
as described in section IV.D.9.
Demonstration of performance provides
an option for PWSs with
presedimentation processes that do not
meet these prescribed conditions for
treatment credit and for PWSs who seek
greater than 0.5-log Cryptosporidium
treatment credit for their
presedimentation processes.
PWSs are not eligible for
Cryptosporidium treatment credit for a
presedimentation process if their
sampling point for the source water
Cryptosporidium monitoring used for
bin classification was after (i.e.,
downstream of) the presedimentation
process. In this case, the removal
achieved by the presedimentation
process will be reflected in the
monitoring results and bin
classification.
b. Background and Analysis
Presedimentation involves passing
raw water through retention basins in
which particulate material is removed
through settling. PWSs use
presedimentation to reduce and
stabilize particle concentrations prior to
the primary clarification and filtration
processes in a treatment plant.
Presedimentation is often operated at
higher hydraulic overflow rates than
conventional sedimentation (the
sedimentation process that directly
precedes filtration in a conventional
treatment plant) and may not involve
coagulant addition. PWSs may operate a
presedimentation process only during
periods of high raw water turbidity.
As a process for removing particles,
presedimentation can reduce
Cryptosporidium levels to some degree.
In addition, presedimentation can
improve the performance of subsequent
treatment processes by dampening
variability in raw water quality. The
efficacy of presedimentation in
removing particles, including
Cryptosporidium, is influenced by the
use of coagulant, the hydraulic loading
rate, water quality parameters like
temperature and turbidity, and physical
characteristics of the sedimentation
basin.
The Stage 2 M-DBP Advisory
Committee recommended 0.5-log
Cryptosporidium treatment credit for
presedimentation with coagulation
(USEPA 2000a). The August 11, 2003
proposal included criteria, which were
similar to those in today's final rule, for
PWSs to receive this credit (USEPA
2003a). The following discussion
summarizes the basis for this credit and
for differences in associated
requirements between the proposal and
today's final rule.
In the proposal, EPA reviewed
published studies of Cryptosporidium
removal through conventional
sedimentation processes by Payment
and Franco (1993), Kelly et al. '(1995),
Patania et al. (1995), States et al. (1997),
Edzwald and Kelly (1998), and Dugan et
al. (2001). These studies included
bench-, pilot-, and full-scale processes,
and the reported levels of
Cryptosporidium removal varied
widely, ranging from 0.4- to 3.8-log. In
addition, these studies also supported
two other significant findings:
(1) Proper coagulation significantly
improves Cryptosporidium removal through
sedimentation. In Dugan et al. (2001), for
example, average Cryptosporidium removal
across a sedimentation basin was 1.3-log with
optimal coagulation and decreased to 0.2-log
when the coagulant dose was insufficient.
(2) The removal of aerobic spores correlates
well with the removal of Cryptosporidium
when a coagulant is present. This indicates
that aerobic spores, which are naturally
present in surface waters, may be used as an
indicator of Cryptosporidium removal in
coagulated full-scale sedimentation
processes.
Cryptosporidium removal efficiencies
in conventional sedimentation may be
higher than in presedimentation due to
differences in hydraulic loading rates,
coagulant doses, and other factors. EPA
identified no published studies of
Cryptosporidium removal through
presedimentation processes. In the
proposal, however, EPA evaluated data
on the removal of aerobic spores in the
presedimentation processes of three
PWSs as an indicator of
Cryptosporidium removal (USEPA
2003a). All three PWSs added a
coagulant (polymer, metal salts, or
recycled sludge) to the
presedimentation process. The mean
removal of aerobic spores through
presedimentation in the three PWSs
ranged from 0.5- to 1.1-log over time
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spans ranging from several months to
several years.
These data support the finding that
full-scale presedimentation processes
can achieve Cryptosporidium removals
of 0.5-log and greater under routine
operating conditions and over an
extended time period. Accordingly, EPA
concluded that 0.5-log Cryptosporidium
treatment credit for presedimentation
processes is appropriate under certain
conditions. Today's rule establishes
three conditions for PWSs to receive
this credit.
The first condition for
presedimentation to receive 0.5-log
Cryptosporidium treatment credit is that
the process must treat all flow reaching
the treatment plant. Presedimentation
cannot reduce the Cryptosporidium
level entering a treatment plant by 0.5-
log or greater on a continuous basis if
the process is operated intermittently or
treats only a fraction of the plant flow.
EPA recognizes that for some PWSs,
operating a presedimentation process
intermittently in response to high
turbidity levels is preferable to
continuous operation. By establishing a
requirement for continuous operation as
a condition for treatment credit, EPA is
not recommending against intermittent
operation of presedimentation
processes. Rather, EPA is only
identifying one of the conditions under
which a 0.5-log Cryptosporidium
treatment credit for presedimentation
appears to be justified.
A second condition for
presedimentation treatment credit is
that the process must operate with
coagulant addition. Available data
support awarding 0.5-log
Cryptosporidium treatment credit to a
presedimentation process only when a
coagulant is present. The full-scale
presedimentation data reviewed in the
proposal involved coagulant addition,
and literature studies indicate that
Cryptosporidium removal through
sedimentation can be substantially
lower in the absence of sufficient
coagulant. Further, the Stage 2 M-DBP
Advisory Committee specifically
recommended 0.5-log Cryptosporidium
treatment credit for presedimentation
with coagulation (USEPA ZOOOa). Based
on these factors. EPA concluded that
coagulation is a necessary condition for
PWSs to receive treatment credit for
presedimentation.
The third condition for awarding
treatment credit to presedimentation is
that the process must achieve a monthly
mean turbidity reduction of at least 0.5-
log or meet alternative State-approved
performance criteria. This requirement
stems from a recommendation by the
SAB, which reviewed data for awarding
treatment credit to presedimentation
under the LT2ESWTR. In their report,
the SAB concluded that available data
were minimal to support 0.5-log
prescribed credit for presedimentation
and recommended that performance
criteria other than overflow rate be
included if credit is given for
presedimentation [SAB 2003).
In response to this recommendation
by the SAB, EPA analyzed the
relationship between removal of aerobic
spores (as an indicator of
Cryptosporidium removal) and
reduction in turbidity in the full-scale
presedimentation processes of three
PWSs. The results of this analysis,
which are shown in Table IV.D-2,
suggest that presedimentation processes
achieving a monthly mean reduction in
turbidity of at least 0.5-log have a high
likelihood of reducing mean
Cryptosporidium levels by 0.5-log or
more. Consequently, EPA concluded
that turbidity reduction is an
appropriate performance criterion for
awarding Cryptosporidium treatment
credit to presedimentation basins. The
Agency believes this performance
criterion addresses the concern raised
by the SAB.
TABLE IV.D-2.—RELATIONSHIP BE-
TWEEN MEAN TURBIDITY REDUCTION
AND THE PERCENT OF MONTHS
WHEN MEAN SPORE REMOVAL WAS
AT LEAST 0.5 LOG
Log reduction in turbidity
(monthly mean)
at least 0 1 -log
at least 0.2-log
at least 0 3-log .
at least 0 4-log .
at least 0.5-log
at least 0 6-log
at least 0 7-log
at least 0.8-log
at least 0 9-log ....
at least 1.0-loa
Percent of
months with at
least 0.5 Log
Mean Reduc-
tion in spores
(percent)
64
68
73
78
89
91
90
89
95
96
Source: Data from Cincinnati Water Works,
Kansas City Water Services Department, and
St Louis Water Division
The proposed rule required PWSs to
achieve at least 0.5-log turbidity
reduction through presedimentation in
at least 11 of the 12 previous
consecutive months to be eligible for
presedimentation treatment credit. EPA
recognizes, however, that some PWSs
will not be able to demonstrate at least
0.5-log turbidity reduction through
presedimentation during months when
raw water turbidity is lower. As a result,
these PWSs would not be able to
achieve treatment credit for their
presedimentation basins. To provide
more options for these PWSs. EPA has
modified this requirement in today's
final rule in two respects.
The first modification is that in
today's final rule, PWSs must
demonstrate compliance with the
conditions for presedimentation
treatment credit on a monthly, rather
that a yearly basis. This requirement
allows treatment credit for
presedimentation in any month a PWS
can demonstrate at least 0.5-log
turbidity reduction, even if the PWS
cannot achieve this level of turbidity
reduction in all months of the year.
A PWS that meets the conditions for
presedimentation treatment credit for
only part of the year must implement
other microbial toolbox options to
comply with Cryptosporidium treatment
requirements in the remainder of the
year. Nevertheless, achieving
presedimentation treatment credit for
even part of the year may benefit certain
PWSs. For example, a PWS may be able
to reduce the level of disinfection it
provides during the months it receives
presedimentation treatment credit, or
this treatment credit may provide a
margin of safety to ensure compliance
with Cryptosporidium treatment
requirements.
The second modification is the
allowance for States to approve
alternative performance criteria to
turbidity reduction that demonstrate at
least 0.5-log mean removal of micron-
sized particulate material through the
presedimentation process. EPA believes
that aerobic spores are an appropriate
alternative criterion. As described
earlier, studies support the use of
aerobic spores as an indicator of
Cryptosporidium removal in coagulated
sedimentation processes. If approved by
the State, a PWS could receive 0.5-log
treatment credit for presedimentation by
demonstrating at least 0.5-log reduction
in aerobic spores. The Toolbox
Guidance Manual provides information
on analytical methods for measuring
aerobic spores. This may provide an
option for PWSs that are not able to
demonstrate 0.5-log turbidity reduction
but have a sufficient concentration of
aerobic spores in their raw water. PWSs
may work with States to identify other
alternative criteria, as well as
appropriate monitoring to support use
of the criteria.
c. Summary of Major Comments
Public comments on the August 11,
2003, LT2ESWTR proposal supported
allowing PWSs to achieve 0.5-log credit
towards Cryptosporidium treatment
requirements for presedimentation with
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691
coagulation. Some commenters also
supported the proposed operational,
monitoring, and performance conditions
required for PWSs to receive this credit.
Other commenters, however, opposed
the proposed requirement for turbidity
reduction as a condition for receiving
presedimentation treatment credit. A
summary of these commenters' concerns
and EPA's responses follows.
Commenters who opposed requiring
turbidity reduction for presedimentation
treatment credit were concerned that
PWSs cannot achieve this criterion
during periods when raw water
turbidity is low. Further, these
commenters stated that turbidity
removal does not reflect the overall
benefits of presedimentation, which
improves the performance of the
primary treatment train by equalizing
water quality. Some commenters also
provided data showing the reduction in
turbidity and aerobic spore levels in the
presedimentation processes of several
PWSs and stated that turbidity removal
may not be an appropriate indicator of
acceptable performance for
presedimentation basins. Several
commenters suggested that EPA
establish a limit on hydraulic overflow
rate in place of a turbidity removal
requirement.
In response, EPA continues to
believes that 0.5-log turbidity reduction
is an appropriate performance indicator
for 0.5-log Cryptosporidium reduction
in presedimentation processes. EPA has
reviewed the additional data submitted
by commenters on the removal of
turbidity and aerobic spores (as an
indicator of Cryptosporidium removal)
in full-scale presedimentation basins.
These data are consistent with data
reviewed for the proposal in showing
that when turbidity removal was below
0.5-log, removal of aerobic spores was
also usually below 0.5-log. Conversely,
when turbidity reduction exceeded 0.5-
log, aerobic spore removal was typically
higher than 0.5-log. Consequently, while
there is not a one-to-one relationship
between reduction in turbidity and
reduction in aerobic spores, 0.5-log
turbidity reduction is a reasonable
indicator of when Cryptosporidium
removal is likely to be at least 0.5-log.
EPA recognizes, though, that 0.5-log
turbidity reduction through
presedimentation will not be feasible for
some PWSs when raw water turbidity is
low. Today's final rule contains several
provisions to address this concern. First,
PWSs can receive credit for
presedimentation during any month the
process achieves 0.5-log turbidity
removal. Thus, PWSs that cannot
achieve 0.5-log turbidity reduction year-
round may receive credit for
presedimentation in those months when
they can meet this condition. Today's
rule also allows PWSs to receive
presedimentation credit using State-
approved performance criteria other
than turbidity reduction. If approved by
the State, a PWS may receive credit for
presedimentation by demonstrating, for
example, 0.5-log reduction in aerobic
spores. Finally, if presedimentation
improves treatment plant performance
by reducing and equalizing particle
loading, a PWS can receive additional
treatment credit under today's rule for
achieving lower filtered water turbidity
(see section IV.D.7).
5. Two-Stage Lime Softening
a. Today's Rule
Lime softening in drinking water
treatment involves the addition of lime
and other chemicals to remove hardness
(calcium and magnesium) through
precipitation. In single-stage softening,
chemical addition and hardness
precipitation occur in a single
clarification process prior to filtration.
In two-stage softening, chemical
addition and hardness precipitation
occur in each of two sequential
clarification processes prior to filtration.
In some water treatment plants, a
portion of the raw water bypasses a
softening process (i.e., split softening) in
order to achieve a desired pH and
alkalinity level in the treated water.
Under today's rule, single-stage
softening with filtration receives a
prescribed 3.0-log credit towards
Cryptosporidium treatment
requirements, which is equivalent to
conventional treatment (see section
IV.B). Two-stage softening receives an
additional 0.5-log Cryptosporidium
treatment credit during any month a
PWS meets the following conditions:
(1) Chemical addition and hardness
precipitation occur in two separate and
sequential softening stages prior to filtration;
and
(2) Both softening stages treat the entire
plant flow taken from surface water sources
orGWUDI (i.e., no portion of the plant flow
from a surface water source may bypass
either softening st
Alternatively, PWSs may apply to the
State for Cryptosporidium treatment
credit for softening processes using a
demonstration of performance, as
described in section IV.D.9.
Demonstration of performance provides
an option for PWSs with softening
processes that do not meet these
conditions for prescribed treatment
credit and for PWSs who seek greater
than the prescribed Cryptosporidium
treatment credit for their softening
processes.
b. Background and Analysis
Lime softening is a common practice
that PWSs use to reduce water hardness,
which is primarily calcium and
magnesium. The addition of lime
elevates the pH of the raw water.
Elevation to pH 9.4 or higher causes
precipitation of calcium carbonate and
further elevation to pH 10.6 or higher
causes precipitation of magnesium
hydroxide. Soda ash may be added with
lime to precipitate non-carbonate
hardness. Removal of the precipitate
occurs through clarification (e.g.,
sedimentation basin) and filtration
processes. Coagulants and recycled
softening sludge are often used to
enhance removal. In two-stage
softening, the second stage is commonly
used to precipitate magnesium, along
with increased levels of calcium.
In addition to reducing hardness,
softening processes remove particulate
material present in the raw water,
including microbial pathogens like
Cryptosporidium. Particulate material
flocculates with the softening
precipitate and is removed through the
clarification and filtration processes,
similar to a conventional treatment
plant. The degree of Cryptosporidium
removal will depend on the amount of
precipitate formation, the use of
coagulants, the raw water quality, and
other factors. Available data indicate
that the elevated pH used in softening
does not inactivate Cryptosporidium or
Giardia (Logsdon et al. 1994, Li et al.
2001), though it does inactivate some
microorganisms like viruses (Battigelli
and Sobsey, 1993, Logsdon et al. 1994).
The Stage 2 M-DBP Advisory
Committee recommended that lime
softening be eligible for up to 1.0-log
additional Cryptosporidium treatment
credit based on a site-specific
demonstration of performance, but did
not recommend any prescribed credit
for this process (USEPA ZOOOa). After
reviewing available data, however, EPA
included a prescribed 0.5-log
Cryptosporidium treatment credit for
two-stage lime softening in the August
11, 2003 proposal (USEPA 2003a). This
approach reflected a recommendation
by the SAB, which supported an
additional 0.5-log treatment credit for
two-stage lime softening if all the water
passes through both stages (SAB 2003).
The proposal also allowed for greater
treatment credit through a
demonstration of performance. The
following discussion summarizes the
basis for the lime softening treatment
credit in today's final rule and
differences with the proposal.
In the proposal, EPA reviewed a study
by Logsdon et al. (1994) that evaluated
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Cryptosporidium removal in full-scale
lime softening plants. Cryptosporidium
was detected in the raw water at 5
plants: one single-stage plant and four
two-stage plants. Based on measured
levels, the removal of Cryptosporidium
across the softening clarification
(sedimentation) stages was 1.0-log in the
single stage plant and ranged from 1.1-
to 2.3-log in the two-stage plants.
Cryptosporidium reductions from raw to
filtered water were 0.6- and 2.2-log in
the single stage plant and ranged from
greater than 2.67- to greater than 3.85-
log in the two-stage plants.
EPA also evaluated data collected by
PWSs on the removal of aerobic spores
in full-scale lime softening plants. As
discussed earlier, studies have shown
the removal of aerobic spores to be an
indicator for Cryptosporidium removal.
and one pilot-scale study of a softening
plant found significantly greater
removal of Cryptosporidium than
aerobic spores under similar treatment
conditions (Clark et al., 2001). For the
full-scale plants, average reductions in
aerobic spores across the softening
clarification stages were 2.4- and 2.8-log
for two plants that practice two-stage
softening and were 1.6- and 2.4-log for
two plants that practice single-stage
softening (USEPA 2003a).
The Cryptosporidium removal data
from Logsdon et al. (1994) and the
aerobic spore removal data provided by
PWSs indicate that a lime softening
clarification stage can achieve greater
than 0.5-log Cryptosporidium removal
during routine operation. Consequently,
EPA agrees with the SAB
recommendation to award an additional
0.5-log Cryptosporidium treatment
credit for two-stage softening. Today's
rule establishes two-conditions for
PWSs to receive this credit.
The first condition for 0.5-log
treatment credit for two-stage softening
is that chemical addition and hardness
precipitation must occur in two separate
and sequential softening stages prior to
filtration. The purpose of this condition
is to ensure that plants receiving
additional credit for two-stage softening
actually have softening and associated
particle removal occurring in each of
two sequential clarification stages.
Plants with other types of clarification
processes in series with a softening
stage are not eligible for two-stage
softening credit. Such plants may,
however, be eligible for additional
treatment credit for other microbial
toolbox options, such as
presedimentation, or may achieve
additional credit through a
demonstration of performance.
The second condition for two-stage
softening treatment credit is that both
softening stages must treat the entire
plant flow taken from a surface water
source or GWUDI. The SAB
recommended this condition, which
reflects the understanding that a
softening stage is unlikely to reduce
overall Cryptosporidium levels by 0.5-
log or more if it treats only a fraction of
the plant flow.
EPA recognizes that some PWSs using
softening will bypass a softening stage
in order to maintain a desired pH and
alkalinity level in the treated water, and
EPA is not recommending against this
practice generally. Rather, the
restriction on bypassing a softening
stage in today's rule applies only to
PWSs that seek additional treatment
credit for softening. Additionally, plants
that soften both surface water and
ground water are eligible for softening
treatment credit if they bypass a
softening stage only with ground water
that is not under the direct influence of
surface water.
The proposal also required that a
coagulant be present in both clarifiers
for a PWS to be eligible for additional
treatment credit for two-stage softening.
EPA is not establishing this requirement
in today's final rule. While many PWSs
that practice softening add coagulants to
improve the removal of precipitates and
other particles, the SAB did not
recommend coagulant addition as a
condition for receiving treatment credit.
Further, available data do not indicate
that additional coagulant is necessary to
achieve at least 0.5-log Cryptosporidium
removal across a softening clarification
stage if hardness precipitation is
occurring.
c. Summary of Major Comments
Public comments on the August 11,
2003, LT2ESWTR proposal supported
awarding additional Cryptosporidium
treatment credit for lime softening
processes. EPA received specific
comments on the types of lime softening
processes eligible for additional
treatment credit, the amount of
additional treatment credit awarded,
and the need for a coagulant. A
summary of these commenters' concerns
and EPA's responses follows.
In regard to the types of lime
softening processes eligible for
treatment credit, commenters
recommended that EPA better define
two-stage softening. Commenters stated
that two-stage softening involves two
separate reaction chambers with the
addition of the softening chemical at the
beginning of each chamber. Some
commenters recommended that
eligibility for additional treatment credit
should be based on the level of
softening precipitate formed or the
settled water turbidity and not on
whether a plant practices single- or two-
stage softening. Another commenter
recommended that any plant designs
with multiple, continuously operated
clarification processes in series should
be eligible for additional treatment
credit.
In response, EPA has refined the
definition of two-stage softening in
today's final rule, which requires that
softening processes employ chemical
addition and hardness precipitation in
two sequential stages to be eligible for
the prescribed additional treatment
credit. EPA agrees with commenters that
the level of precipitate formation will
influence the degree of Cryptosporidium
removal. Available data, however,
indicate that two-stage softening will
generally achieve more
Cryptosporidium removal than single-
stage softening. Consequently, EPA
believes that two-stage softening should
be eligible for the additional prescribed
0.5-log treatment credit. Plants with
single-stage softening may receive
additional treatment credit under
today's rule through a demonstration of
performance. Similarly, plants that
employ multiple clarification process
other than softening in series may
receive additional treatment credit
either as presedimentation or through a
demonstration of performance.
With respect to the amount of
additional Cryptosporidium treatment
credit for two-stage softening, most
commenters supported awarding 3.0-log
treatment credit to single-stage lime
softening, equivalent to a conventional
treatment plant, and an additional
prescribed 0.5-log treatment credit for
two-stage lime softening. A few
commenters requested that two-stage
lime be granted an additional
Cryptosporidium treatment credit of 1.0-
log, based on the level of aerobic spore
removal measured across softening
clarifiers.
EPA agrees with most commenters
and the SAB that 0.5-log is an
appropriate level of additional
prescribed Cryptosporidium treatment
credit for two-stage softening. Where
plants are able to demonstrate a
significantly higher level of removal of
Cryptosporidium or an indicator like
aerobic spores, they may apply for
additional treatment credit through a
demonstration of performance.
Commenters stated that achieving
particle removal in lime softening is not
dependent on a coagulant like a metal
salt or organic polymer. Some
commenters recommended that
coagulant be defined to include
softening chemicals like lime and
magnesium hydroxide (a softening
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693
precipitate). EPA agrees that available
data do not demonstrate the need for a
traditional metal salt or organic
coagulant for effective particle removal
in softening. Accordingly, today's final
rule does not require the use of a
coagulant as a condition for additional
treatment credit in two-stage softening.
Instead, each stage must involve
chemical addition and hardness
precipitation. EPA intends this
requirement to ensure that softening and
associated particle removal occur in
each stage if a plant is to receive
additional treatment credit for two-stage
softening.
6. Bank Filtration
a. Today's Rule
Bank filtration is a water treatment
process that uses one or more pumping
wells to induce or enhance natural
surface water infiltration and to recover
that surface water from the subsurface
after passage through a river bed or
bank(s). Under today's rule, bank
filtration that serves as pretreatment to
a filtration plant is eligible for
Cryptosporidium treatment credit if it
meets the following criteria:
• Wells with a ground water flow
path of at least 25 feet receive 0.5-log
treatment credit; wells with a ground
water flow path of at least 50 feet
receive 1.0-log treatment credit. The
ground water flow path must be
determined as specified in this section.
• Only wells in granular aquifers are
eligible for treatment credit. Granular
aquifers are those comprised of sand,
clay, silt, rock fragments, pebbles or
larger particles, and minor cement. A
system must characterize the aquifer at
the well site to determine aquifer
properties. Systems must extract a core
from the aquifer and demonstrate that in
at least 90 percent of the core length,
grains less than 1.0 mm in diameter
constitute at least 10 percent of the core
material.
• Only horizontal and vertical wells
are eligible for treatment credit.
• For vertical wells, the ground water
flow path is the measured distance from
the edge of the surface water body under
high flow conditions (determined by the
100 year floodplain elevation boundary
or by the floodway, as defined in
Federal Emergency Management Agency
flood hazard maps) to the well screen.
For horizontal wells, the ground water
flow path is the measured distance from
the bed of the river under normal flow
conditions to the closest horizontal well
lateral screen.
• Systems must monitor each
wellhead for turbidity at least once
every iour hours while the bank
filtration process is in operation. If
monthly average turbidity levels, based
on daily maximum values in the well,
exceed 1 NTU, the system must report
this result to the State and conduct an
assessment within 30 days to determine
the cause of the high turbidity levels in
the well. If the State determines that
microbial removal has been
compromised, the State may revoke
treatment credit until the system
implements corrective actions approved
by the State to remediate the problem.
• Springs and infiltration galleries are
not eligible for treatment credit under
this section, but are eligible for credit
under the demonstration of performance
provisions described in section IV.D.9.
Alternatively, PWSs may apply to the
State for Cryptosporidium treatment
credit for bank filtration using a
demonstration of performance. States
may award greater than 1.0-log
Cryptosporidium treatment credit for
bank filtration based on a site-specific
demonstration. For a bank filtration
demonstration of performance study,
today's rule establishes the following
criteria:
• The study must follow a State-
approved protocol and must involve the
collection of data on the removal of
Cryptosporidium or a surrogate for
Cryptosporidium and related
hydrogeologic and water quality
parameters during the full range of
operating conditions.
• The study must include sampling
both from the production well(s) and
from monitoring wells that are screened
and located along the shortest flow path
between the surface water source and
the production well(s).
The Toolbox Guidance Manual provides
guidance on conducting site-specific
bank filtration studies, including
analytical methods for measuring
aerobic and anaerobic spores, which
may serve as surrogates for
Cryptosporidium removal.
PWSs using existing bank filtration as
pretreatment to a filtration plant at the
time the PWS must begin source water
Cryptosporidium monitoring under
today's rule must sample the well for
the purpose of determining bin
classification. These PWSs are not
eligible to receive additional treatment
credit for bank filtration. In these cases,
the performance of the bank filtration
process in reducing Cryptosporidium
levels will be reflected in the
monitoring results and bin
classification.
PWSs using bank filtration without
additional filtration must collect source
water samples in the surface water (i.e.,
prior to bank filtration) to determine bin
classification unless the State approves
an alternative monitoring location. This
applies to systems using bank filtration
to meet the Cryptosporidium removal
requirements of the IESWTR or
LTlESWTR under the provisions for
alternative filtration demonstration in
40 CFR 141.173(b) or 141.552(a). Bank
filtration criteria for Cryptosporidium
removal credit under today's rule do not
apply to existing State actions regarding
alternative filtration Cryptosporidium
removal credit for IESWTR or
LTlESWTR compliance. PWSs using
GWUDI sources must collect samples
from the well (i.e., the ground water).
b. Background and Analysis
Bank filtration is a water treatment
process that makes use of surface water
that has naturally infiltrated into ground
water through a river bed or bank and
is recovered via a pumping well. River
bed infiltration is typically enhanced by
the pumping action of nearby wells.
Bank filtrate is water that is drawn into
a pumping well from a nearby surface
water source after having traveled
through the subsurface (i.e., aquifer) and
mixing with other ground water. In bank
filtration, microorganisms and other
particles are removed by contact with
the aquifer materials.
The Stage 2 M-DBP Advisory
Committee recommended a prescribed
Cryptosporidium treatment credit of 1.0-
log for bank filtration with the option
for PWSs to receive greater treatment
credit through a site-specific
demonstration of performance (USEPA
2000a). The August 11, 2003 proposal
included criteria, similar to those in
today's final rule, for PWSs to receive
prescribed treatment credits of 0.5- and
1.0-log (USEPA 2000a). The following
discussion summarizes the basis for
these credits and for differences in
associated requirements between the
proposal and today's final rule.
Directly measuring the removal of
Cryptosporidium through bank filtration
is difficult due to the relatively low
oocyst concentrations typically present
in surface and ground water. In the
proposal, EPA reviewed bank filtration
field studies that measured the removal
of Cryptosporidium surrogates,
specifically aerobic and anaerobic
bacterial endospores (Havelaar et al.
1995, Rice et al. 1996, Pang et al. 1998,
Arora et al. 2000, Medema et al. 2000,
and Wang et al. 2001). These
microorganisms are suitable surrogates
because they are resistant to inactivation
in the subsurface, similar in size and
shape to Cryptosporidium, and present
in both surface and ground water at
concentrations that allow calculation of
log removal across the surface water-
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ground water interface and within the
aquifer. In addition, EPA reviewed
studies of the transport of
Cryptosporidium through soil materials
in laboratory column studies (Harter et
al. 2000).
Based on these studies, EPA
concluded that bank filtration processes
can achieve significant Cryptosporidium
removal and that prescribed
Cryptosporidium treatment credits of
0.5-log and 1.0-log are appropriate
under certain conditions. These
conditions are as follows: Only wells
located in unconsolidated,
predominantly sandy aquifers are
eligible
The bank filtration removal process
performs most efficiently when the
aquifer is comprised of granular
materials with open pore-space for
water flow around the grains. In these
granular porous aquifers, the flow path
is meandering, thereby providing ample
opportunity for microorganisms to come
into contact with and attach to a grain
surface. Accordingly, only wells located
in unconsolidated, granular aquifers are
eligible for bank filtration treatment
credit.
Granular aquifers are those comprised
of sand, clay, silt, rock fragments,
pebbles or larger particles and minor
cement. Specifically, a PWS must
extract a core from the aquifer and
demonstrate that in at least 90 percent
of the core length, grains less than f.O
mm in diameter constitute at least 10
percent of the core material. Laboratory
column studies of Cryptosporidium
transport (Harter et al., 2000) and field
studies of aerobic bacterial endospore
passage in the subsurface (Pang et al.,
1998) support these criteria.
Only Horizontal and Vertical Wells Are
Eligible
A number of devices are used for the
collection of ground water including
horizontal and vertical wells, spring
boxes, and infiltration galleries. Among
these, only horizontal and vertical wells
are eligible for log removal credit
because spring boxes and infiltration
galleries are components of engineered
systems designed to speed transport
through or by-pass the naturally
protective riverbed or bank.
Wells Must be Located 25 Feet From the
Surface Water Source To Be Eligible for
0.5-Log Credit and Located at Least 50
Feet From the Surface Water Source To
Be Eligible for 1.0-Log Credit
A vertical or horizontal well located
adjacent to a surface water body is
eligible for bank filtration credit if there
is sufficient ground water flow path
length to effectively remove oocysts.
Specifically, the ground water flow path
must be at least 25 feet and 50 feet for
0.5-log and 1.0-log Cryptosporidium
treatment credit, respectively. The
ground water flow path to a vertical
well is the measured distance from the
edge of the surface water body under
high flow conditions (determined by the
100 year floodplain elevation boundary
or floodway, as defined in Federal
Emergency Management Agency flood
hazard maps) to the wellhead. The
ground water flow path to a horizontal
well is the measured distance from the
bed of the river under normal flow
conditions to the closest horizontal well
lateral.
These required flow path distances for
Cryptosporidium treatment credit are
based on pathogen and surrogate
monitoring data from bank filtration
field studies (Wang et al. 2001, Havelaar
et al. 1995, Medema et al. 2000). Results
from these studies show that significant
removal of anaerobic and aerobic spores
can occur during passage across the
surface water—ground water interface,
with lesser removal occurring during
ground water transport within the
aquifer away from that interface. The
ground water—surface water interface is
usually comprised of finer grained
material that lines the bottom of the
riverbed. Typically, the thickness of the
interface is small, ranging from a few
inches to a foot.
These results suggest that during
normal and low surface water
elevations, the surface water-ground
water interface will perform effectively
to remove microbial contamination like
Cryptosporidium. During short periods
of flooding, substantially lower removal
rates may occur due to scouring of the
riverbed and removal of the protective,
fine-grained material. Assessing the
mean Cryptosporidium removal that a
bank filtration process will achieve over
the period of a year requires
consideration of both high and low
removal periods. By considering all time
intervals with differing removal rates
over the period of a year, EPA
concluded that 0.5-log removal over 25
feet and 1.0-log removal over 50 feet .are
appropriate estimates of the mean
performance of a bank filtration process
(USEPA 2003a).
Wells Must Be Continuously Monitored
for Turbidity
Similar pathogen removal
mechanisms are expected to occur in
slow sand filtration and bank filtration.
Under the 40 CFR 141.73(b)(l), the
turbidity level of slow sand filtered
water must be 1 NTU or less in 95
percent of the measurements taken each
month. Turbidity sampling is required
once every four hours, but may be
reduced to once per day under certain
conditions. Just as turbidity monitoring
is used to provide assurance that the
removal credit assigned to a slow sand
filter is being realized, today's rule
requires turbidity monitoring at least
once every 4 hours for all bank filtration
wells that receive treatment credit.
If monthly average turbidity levels
(based on daily maximum values in the
well) exceed 1 NTU, the PWS must
report this result to the State and
conduct an assessment to determine the
cause of the high turbidity levels in the
well. If the State determines that
microbial removal has been
compromised, the State may revoke
treatment credit until the PWS
implements corrective actions to
remediate the problem.
Demonstration of Performance
EPA recognizes that some bank
filtration processes may achieve mean
Cryptosporidium removal greater than
1-log. Consequently, today's rule allows
PWSs to receive greater than 1.0-log
Cryptosporidium treatment credit for
bank filtration through a State-approved
demonstration of performance study.
This allowance is a change from the
proposed rule, which did not explicitly
recognize demonstration of performance
for bank filtration (USEPA 2003a). This
change reflects EPA's agreement with
public comment, described next, which
recommended that EPA explicitly
recognize the option to conduct a bank
filtration performance study for greater
than 1.0-log treatment credit.
A demonstration of performance
study must involve the collection of
data on the removal of Cryptosporidium
or surrogates and related hydrogeologic
and water quality parameters during the
full range of operating conditions. PWSs
must sample from both the production
well(s) and one or more monitoring
wells that are screened and located
along the shortest flow path between the
surface water and the production
well(s). This will allow determination of
the removal efficiency of the aquifer.
Because directly measuring
Cryptosporidium removal will not be
feasible for most PWSs. today's rule
allows PWSs to sample for a State-
approved indicator, such as aerobic
bacterial endospores. Research has
shown that aerobic spores can be very
mobile in the subsurface environment
(Pang et al. 1998), and data collected by
Wang et al. (2001) indicate that aerobic
spores are present in some surface
waters in sufficient quantity to allow
measurement of log removal values.
EPA has provided guidance on
conducting site-specific bank filtration
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studies in the Toolbox Guidance
Manual. This guidance discusses data
needs and analysis for a performance
demonstration so that the State may
tailor the study plan to meet site-
specific hydrogeological and operational
conditions.
In summary, EPA believes that full-
scale field data support prescribed
Cryptosporidium treatment credit up to
1.0-log for bank filtration under the
required conditions for set-back
distance, aquifer material, collection
device type, and turbidity monitoring.
Demonstration of performance provides
an appropriate opportunity for States to
award higher Cryptosporidium
treatment credit for bank filtration on a
site-specific basis.
For PWSs using bank filtration when
they must conduct source water
monitoring for bin classification, the
required sampling locations reflect the
intent for this monitoring to capture the
level of Cryptosporidium entering a
PWS's primary filtration treatment
process. Where bank filtration serves as
pretreatment to a filtration plant, PWSs.
must collect source water samples after
bank filtration but prior to the filtration
plant. In this case, the Cryptosporidium
removal that bank filtration achieves
will be reflected in the monitoring
results and bin classification for the
filtration plant. In contrast, where bank
filtration is the primary filtration
process, meaning that a PWS uses bank
filtration to comply with the
Cryptosporidium treatment
requirements of the IESWTR or
LTlESWTR, PWSs must collect samples
in the surface water source (e.g, the
river).
c. Summary of Major Comments
Public comments on the August 11,
2003, LT2ESWTR proposal supported
awarding Cryptosporidium treatment
credit for bank filtration. Many
commenters, however, stated that the
proposed levels of credit (0.5- and 1.0-
log) were insufficient. To address this
issue, commenters supported allowing
PWSs to obtain greater treatment credit
by performing a site-specific study of
bank filtration removal efficiency.
Commenters recommended that site-
specific bank filtration studies involve
the measurement of surrogates for
Cryptosporidium removal using
monitoring wells located along the
shortest flow path between the surface
water and the production well.
EPA agrees that some bank filtration
sites may achieve greater than 1.0-log
Cryptosporidium removal. Today's rule
establishes the proposed bank filtration
Cryptosporidium treatment credits of
0.5- and 1.0-log and allows PWSs to
apply to the State for higher levels of
credit through a site-specific
demonstration of performance. In such
a study, PWSs must measure the
removal of Cryptosporidium or a State-
approved surrogate using monitoring
wells located along the flow path, as
recommended by commenters.
Some commenters cited research
addressing appropriate surrogate
organisms for estimating
Cryptosporidium removal in surface
water treatment plants and bank
filtration sites. Commenters
recommended that EPA recognize
aerobic endospores as a surrogate
measure in Cryptosporidium removal
studies, including those for bank
filtration.
EPA agrees that based on available
information, aerobic spores are suitable
Cryptosporidium removal surrogates for
bank filtration processes due to their
size, resistance to inactivation, and
concentration in surface and ground
waters. Data from several bank filtration
sites on the use of aerobic spores as a
Cryptosporidium removal surrogate are
available. The Toolbox Guidance
Manual identifies aerobic spores as
suitable in conjunction with other
hydrogeologic data for making site-
specific determinations for additional
Cryptosporidium removal credit.
In guidance, EPA suggests that where
feasible, PWSs measure diatom species
in conjunction with aerobic spores in
bank filtration studies because
Cryptosporidium oocysts are
intermediate in size between the two
surrogate groups. Further, EPA
recognizes the current uncertainties and
limitations in available information on
surrogates for bank filtration and will
update guidance as warranted by new
information.
7. Combined Filter Performance
a. Today's Rule
For water treatment plants that use
filtration, the turbidity of the filtered
water is an indicator of how effectively
the plant is removing particulate matter,
including microbial pathogens, from the
raw water. PWSs using conventional
filtration treatment or direct filtration
receive an additional 0.5-log
Cryptosporidium treatment credit
during any month the PWS meets the
following standard:
• The turbidity level of representative
samples of a PWS's filtered water (i.e.,
the combined filter effluent) is less than
or equal to 0.15 NTU in at least 95
percent of the measurements taken each
month. PWSs must continue to measure
turbidity as specified in 40 CFR
141.74(a) and (c), which generally
require sampling at least every four
hours using approved methods.
PWSs using other types of filtration
processes, including slow sand,
diatomaceous earth, membranes, bag, or
cartridge filtration, are not eligible for
this treatment credit.
b. Background and Analysis
Turbidity is a method defined
parameter that is based on measuring
the amount of light scattered by
suspended particles in a solution. This
measure can detect the presence of a
wide variety of particles in water,
including microorganisms, but cannot
provide specific information on particle
type, number, or size. In filtered water,
the turbidity level indicates how well
the filtration and other upstream
clarification processes have performed
in removing particles from the raw
water, with lower turbidity indicating
better particle removal. Thus, lower
filtered water turbidity is associated
with a decreased likelihood that
microbial pathogens like
Cryptosporidium have passed through
the filtration plant and into the water
distributed to consumers.
Under existing regulations, PWSs that
filter must monitor turbidity in the
combined filter effluent (CFE) at least
every four hours using approved
methods, although States may reduce
this frequency to once per day for PWSs
serving 500 people or fewer (40 CFR
141.74(a) and (c)). For PWSs using
conventional or direct filtration, at least
95 percent of the CFE turbidity
measurements must be less than or
equal to 0.3 NTU, and the turbidity
must never exceed I NTU (40 CFR
141.173(a) and 141.551(a)-(b)).
The Stage 2 M-DBP Advisory
Committee recommended an additional
0.5-log Cryptosporidium treatment
credit for PWSs that achieve a CFE
turbidity less than or equal to 0.15 NTU
in at least 95 percent of measurements
per month (USEPA 2000a). This 95th
percentile turbidity standard is one half
the level required under existing
regulations for PWSs using conventional
or direct filtration, as stated earlier. The
August 11, 2003 proposal included this
treatment credit for PWSs using
conventional or direct filtration (USEPA
2003a), and EPA is establishing it in
today's final rule with no changes from
the proposal. The following discussion
summarizes the basis for this treatment
credit.
In the proposal, EPA analyzed the
improvement in Cryptosporidium
removal that conventional and direct
filtration plants realize when operating
at lower effluent turbidity levels. For
this analysis, EPA estimated that PWSs
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complying with the existing 95th
percentile CFE turbidity standard of 0.3
NTU will typically operate with filter
effluent turbidity between 0.1-0.2 NTU;
PWSs complying with a CFE standard of
0.15 NTU were estimated to operate
with filter effluent turbidity less than
0.1 NTU. Accordingly, EPA compared
Cryptosporidium removal efficiencies
when effluent turbidity was below 0.1
NTU with those when effluent turbidity
was in the range of 0.1-0.2 NTU.
Studies by Patania et al. (1995),
Emelko et al. (1999), and Dugan et al.
(2001) observed the average removal of
Cryptosporidium to be 0.5-to 1.2-log
greater when filter effluent turbidity was
less than 0.1 NTU in comparison to
removal with effluent turbidity between
0.1-0.2 NTU. These studies, therefore,
indicate that PWSs complying with a
filter effluent turbidity standard of 0.15
NTU will achieve at least 0.5-log greater
Cryptosporidium removal than PWSs
complying with the existing 0.3 NTU
standard. Based on this finding, EPA
concluded that an additional 0.5-log
Cryptosporidium treatment credit is
appropriate for PWSs using
conventional or direct filtration that
meet a 95th percentile CFE turbidity
standard of 0.15 NTU.
Other types of filtration processes,
such as slow sand, diatomaceous earth.
membranes, bag, or cartridge filtration.
are not eligible for this treatment credit,
These filtration processes remove
Cryptosporidium through different
mechanisms than those operative in
rapid granular media filtration, which is
used in conventional and direct
filtration. Available data do not
establish a similar relationship between
lower filter effluent turbidity and
improved Cryptosporidium removal
efficiency for these other filtration
processes.
The SAB reviewed the proposed
additional Cryptosporidium treatment
credit for PWSs that operate with very
low filtered water turbidity. In their
report, the SAB stated that further
lowering of turbidity would result in
further reductions in Cryptosporidium
in the effluent from filtration processes,
but available data were limited in
showing the exact removal that can be
achieved. Based on the data provided,
the SAB recommended that no
additional treatment credit be given to
plants that demonstrate a CFE turbidity
of 0.15 NTU or less (SAB 2003).
In addressing this SAB
recommendation, EPA recognizes that
precisely quantifying the increase in
Cryptosporidium removal that a
particular filtration plant will realize
when operating at lower filter effluent
turbidity is not generally feasible.
Available data, though, consistently
show that removal of Cryptosporidium
is at least 0.5-log greater when filter
effluent turbidity reflects compliance
with a 0.15 NTU standard in
comparison to a 0.3 NTU standard.
Further, treatment plants operating at
lower filter effluent turbidity will
achieve increased removal of other
microbial pathogens present in the raw
water. In consideration of these factors,
EPA believes that PWSs should receive
an additional 0.5-log Cryptosporidium
treatment credit when at least 95
percent of CFE turbidity measurements
are less than or equal to 0.15 NTU.
Another key issue in establishing
additional treatment credit based on low
filtered water turbidity is the
performance of analytical instruments
(turbidimeters) to accurately measure
turbidity at low levels. In the proposal,
EPA reviewed studies of low level
turbidity measurements by EPA (1998c),
Sadar (1999), and Letterman et al.
(2001). Among the significant findings
of these studies are the following:
(1) On-line turbidimeters typically had a
positive bias (i.e., a higher turbidity reading)
in comparison to bench-top turbidimetors.
EPA expects that most PWSs that receive
additional treatment credit for low filter
effluent turbidity will use on-line
turbidimoters. This finding suggests that the
error in turbidimeter readings may be
generally conservative, so that PWSs will
operate at lower than required turbidity
levels.
(2) Different turbidimoters did not agree
well when used to measure low level
turbidity, which may bo due to differences in
instrument design, this finding suggests that
low level turbidity measurements may be
viewed as a relative indicator of water quality
improvement at a particular PWS but may be
less applicable for making comparisons
among different PWSs.
In addition, the American Society for
Testing and Materials (ASTM) has '
issued standard test methods for
measurement of turbidity below 5 NTU
by on-line (ASTM 2001)'and static:
(ASTM 2003) instruments. These
methods specify that the instrument
should permit detection of turbidity
differences of 0.01 NTU or less in waters
having turbidities of less than 1.00 NTU
(ASTM 2001) and 5.0 NTU (ASTM
2003), respectively.
After reviewing these studies and the
ASTM methods, EPA concluded that
currently available monitoring
equipment can reliably measure
turbidity at levels of 0.15 NTU and
lower. Rigorous calibration and
maintenance of turbidity monitoring
equipment is necessary, however. EPA
has developed guidance on proper
calibration, operation, and maintenance
of turbidimeters (USEPA 1999c).
c. Summary of Major Comments
Public comment on the August 11,
2003, LT2ESWTR proposal supported
awarding additional Cryptosporidium
treatment credit for PWSs that achieve
lower filtered water turbidity.
Commenters raised specific concerns
with the criteria for PWSs to receive this
credit, the available data that support
this credit, and the performance of
turbidimeters for measuring turbidity at
very low levels. A summary of these
comments and EPA's responses follows.
Most commenters supported awarding
0.5-log additional Cryptosporidium
treatment credit for PWSs that achieve
at least 95 percent of CFE turbidity
measurements less than or equal to 0.15
NTU. A few commenters, however,
recommended that PWSs only receive
additional treatment credit for
demonstrating this level of turbidity
performance in each individual filter
effluent (IFE), rather than the CFE. In
addition, one commenter stated that
PWSs should be required to monitor
CFE turbidity every 15 minutes, rather
than every four hours as required under
current regulations.
In response, EPA agrees with the
recommendation of most commenters
and has established additional
Cryptosporidium treatment credit based
on meeting a 95th percentile turbidity
level of 0.15 NTU in the CFE. EPA
recognizes, however, that achieving low
turbidity in each IFE may represent a
higher level of performance than
achieving low turbidity in the CFE. As
described in the next section, EPA has
also established standards for additional
Cryptosporidium treatment credit based
on low IFE turbidity in today's rule.
EPA does not have data indicating that
PWSs should monitor the CFE turbidity
at a higher frequency than every four
hours, as required under existing
regulations. Consequently, EPA is not
changing the frequency of required CFE
turbidity monitoring as a condition for
PWSs to receive additional treatment
credit under today's rule.
One commenter summarized
additional studies that provide data on
the improvement in Cryptosporidium
removal efficiency at lower filter
effluent turbidity levels. According to
this commenter, these studies
demonstrate that lowering filter effluent
turbidity from 0.3 to 0.15 NTU
translates to an improvement in
Cryptosporidium removal of more than
1.5-log, with individual studies showing
a range of >0.7-log to >3-log based on
median removal. EPA finds that these
studies bolster the conclusion that
PWSs operating to meet 0.15 NTU in the
filter effluent will achieve at least 0.5-
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697
log greater Cryptosporidium removal
than PWSs operating to meet 0.3 NTU.
Thus, they support the additional 0.5-
log Cryptosporidium treatment credit
under today's rule for PWSs meeting
0.15 NTU at the 95th percentile in the
CFE.
In regard to the measurement of low
level turbidity, some commenters raised
concerns that turbidimeters used by the
U.S. water supply industry do not agree
when used to measure turbidity in the
0.01 to 0.5 NTU range. Further^ these
differences are independent of the
calibration method used and can be
significant when comparing instruments
by different manufacturers. Other
commenters stated that turbidimeters
can accurately reflect turbidity values
less than 0.15 NTU if properly
calibrated, and some commenters cited
the ASTM method development process
to support this assessment. In addition,
commenters suggested that available
guidance on turbidity measurement
provides quality assurance measure that
can reduce analytical uncertainty.
EPA agrees with commenters that
available methods and instruments are
adequate to demonstrate compliance
with a 0.15 NTU turbidity level. In
particular, EPA believes that monitoring
low level turbidity can be effective for
demonstrating water quality
improvements at individual plants, but
also recognizes that the performance of
turbidimeters used at different plants
may vary. Further, calibration and
maintenance of turbidity monitoring
equipment is critical, and EPA has
developed guidance on these
procedures (USEPA I999c).
8. Individual Filter Performance
a. Today's Rule
PWSs using conventional filtration
treatment or direct filtration receive an
additional 0.5-log Cryptosporidium
treatment credit during any month the
PWS meets the following criteria:
• The filtered water turbidity for each
individual filter is less than or equal to
0.15 NTU in at least 95 percent of the
measurements recorded each month;
and
• No individual filter has a measured
turbidity level greater than 0.3 NTU in
two consecutive measurements taken 15
minutes apart.
PWSs must continue to monitor
turbidity for each individual filter
continuously and record the results
every 15 minutes, as required under 40
CFR 141.174 and 141.560.
PWSs that receive this 0.5-log
Cryptosporidium treatment credit for
individual filter performance also
receive 0.5-log treatment credit for
combined filter performance, as
described in section IV.D.7, for a total
additional treatment credit of 1.0-log.
Conversely, PWSs are not required to
pursue individual filter performance
credit to remain eligible for combined
filter performance credit.
If a PWS has received credit for
individual filter performance to comply
with its Cryptosporidium treatment
requirements and fails to meet the
required criteria for this credit during
any month, the PWS will not incur a
treatment technique violation if the
State determines the following:
• The failure to meet the required
criteria for individual filter performance
treatment credit was due to unusual and
short-term circumstances that could not
reasonably be prevented through
optimizing treatment plant design,
operation, and maintenance; and
• The PWS has experienced no more
than two such failures in any calendar
year.
This treatment credit is not applicable
to other types of filtration processes,
including slow sand, diatomaceous
earth, membranes, bag, or cartridge
filtration.
b. Background and Analysis
Awarding additional treatment credit
for individual filter performance is
based on the expectation that achieving
low filtered water turbiditv in each
individual filter will provide increased
protection against microbial pathogens.
Most treatment plants have multiple
filters. Moderately elevated turbidity in
the effluent from a single filter may not
significantly affect the turbidity of the
combined filter effluent, but may
indicate a reduction in the overall
pathogen removal efficiency of the
filtration process. Consequently, a
primary goal in optimizing water
treatment plant performance is ensuring
that each filter always produces very
low turbidity water.
The criteria for PWSs to achieve the
additional 1.0-log Cryptosporidium
treatment credit for individual filter
performance reflect goals of Phase IV of
the Partnership for Safe Water
(Partnership). The Partnership is a
voluntary cooperative program
involving PWSs, professional
associations, and Federal and State
regulatory agencies that seeks to
increase protection against microbial
contaminants by optimizing water
treatment plant performance. The Stage
2 M-DBP Advisory Committee
recommended 1.0-log treatment credit
for PWSs that successfully participate in
a peer review program and identified
Phase IV of the Partnership as a program
where such credit would be appropriate
(USEPA 2000a).
At the time of the Advisory
Committee recommendation, the
performance goals for Phase IV of the
Partnership reflected those of the EPA
Composite Correction Program (USEPA
1991a) and involved an on-site
evaluation by a third-party team. Phase
IV performance goals for individual
filters included filtered water turbidity
less than 0.1 NTU at least 95 percent of
the time based on daily maximum
values and a maximum measurement of
0.3 NTU. The purpose of the on-site
evaluation was to confirm that a PWS
had met Phase IV performance goals or
had achieved the highest level of
performance given its unique raw water
quality.
After the Stage 2 M-DBP Agreement
in Principle was signed in September
2000, the Partnership eliminated on-site
third-party evaluation as a component
of Phase IV. Instead, Phase IV required
completion of an Optimization
Assessment Spreadsheet in which the
PWS entered water treatment data to
demonstrate that it had achieved Phase
IV performance levels. The application
also required narratives related to the
administrative support and operational
capabilities necessary to sustain
performance long-term.
The August 11, 2003 LT2ESWTR
proposal included a 1.0-log
Cryptosporidium treatment credit for
PWSs that met the individual filter
performance goals of Phase IV of the
Partnership (i.e., 95 percent of daily
maximum values below 0.1 and no
values above 0.3 NTU) (USEPA 2003a).
Rather than requiring an application
package with historical data and
narratives, however, the proposed rule
required PWSs to report filter effluent
turbidity data to the State each month
to demonstrate compliance with these
filter performance goals.
The Partnership modified the Phase
IV goals for individual filter
performance in 2003. A revised goal is
filtered water turbidity less than 0.10
NTU at least 95 percent of the time
based on values recorded at 15 minute
time intervals. Thus, where the earlier
goal was based on daily maximum
values for each filter, the revised goal is
based on all values for each filter—a less
stringent approach. The Partnership
made this modification after finding that
none of the water treatment plants that
had been evaluated could consistently
meet the 0.1 NTU goal using daily
maximum values and, further, that this
goal was biased against plants with
more filters.
In today's final rule, EPA has adjusted
the criteria from the proposal for PWSs
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to receive additional treatment credit
based on individual filter effluent
turbidity. These adjustments are in
response to the changes the Partnership
made to Phase IV individual filter
performance goals. Under today's rule,
PWSs receive 1.0-log additional
Cryptosporidium treatment credit if
effluent turbidity from each filter is less
than or equal to 0.15 NTU at least 95
percent of the time and never exceeds
0.3 NTU in two consecutive
measurements taken 15 minutes apart.
EPA expects that PWSs will operate at
less than 0.1 NTU in order to comply
with a regulatory limit of 0.15 NTU.
Further, EPA believes that assessing
individual filter compliance with a
maximum turbidity level of 0.3 NTU
based on two consecutive measurements
taken 15 minutes apart is appropriate.
This approach allows for brief
fluctuations in turbidimeter readings
that may not indicate a degradation in
filtered water quality to occur without
penalizing a PWS, but it should catch
filters that significantly exceed 0.3 NTU
over the course of a month. EPA applied
this approach to individual filter
monitoring under the IESWTR and
LTlESWTR. Consequently, EPA regards
these criteria as comparable to the
revised Partnership Phase IV standards
for individual filter performance.
In addition, today's rule gives States
authority to determine whether to issue
a treatment technique violation for
PWSs that exceed individual filter
performance limits. This authority
applies in the case where a PWS
receives credit for individual filter
performance to meet the treatment
requirements of today's rule and fails to
achieve the criteria to receive this credit
during a month. If the State determines
that this failure was due to unusual and
short-term circumstances that could not
reasonably be prevented through
treatment optimization, the State may
choose not to issue a treatment
technique violation, which the PWS
otherwise will incur. Because this
authority should be applied only to
unusual plant circumstances, a State
cannot make this determination if a
PWS has experienced more than two
such failures in any calendar year.
EPA is granting States this authority
because PWSs that consistently meet the
criteria for individual filter performance
treatment credit may occasionally
experience short-term deviations from
these criteria due to circumstances
largely beyond the PWS's control. An
example of such a circumstance may be
malfunctioning equipment that a PWS
quickly removes from service, but that
nevertheless prevents the PWS from
fully meeting individual filter
performance criteria in a particular
month. EPA believes that States should
only apply this authority in cases where
PWSs have consistently achieved the
criteria for individual filter performance
treatment credit in previous months.
The approach in today's final rule for
valuing individual filter performance
treatment credit differs from the
approach in the proposal. EPA's intent
in both the proposal and today's rule is
to award an additional 1.0-log
Cryptosporidium treatment credit to
PWSs that meet the criteria for
individual filter performance. In the
proposal, however, PWSs could receive
1.0-log additional treatment credit
specifically for meeting the individual
filter performance criteria, but were
then not eligible to receive any
treatment credit under the combined
filter performance option. In today's
rule, PWSs receive 0.5-log credit for the
individual filter performance option and
also receive an additional 0.5-log
treatment credit for the combined filter
performance option (discussed in
section IV.D.7), resulting in 1.0-log total
additional credit. EPA has made this
modification so that if a PWS fails in an
attempt to achieve individual filter
performance credit, the PWS is clearly
still eligible to received combined filter
performance credit.
In a review of a draft LT2ESWTR
proposal, the SAB recommended that
PWSs receive 0.5-log. rather than 1.0-
log, additional Cryptosporidium
treatment credit for achieving
individual filter effluent turbidity below
0.15 NTU at the 95th percentile ("SAB
2003). In response to this SAB
recommendation, today's rule requires
additional individual filter performance
criteria to support 1.0-log total
additional treatment credit. Specifically,
today's rule incorporates the
Partnership Phase IV performance goal
that individual filter effluent turbidity
never exceed 0.3 NTU (as described
earlier, EPA concluded that determining
compliance with this standard based on
two consecutive measurements taken 15
minutes is appropriate and consistent
with existing regulations). Thus, EPA
believes that these criteria, in
conjunction with the expectation that
controlling effluent turbidity at all
filters individually rather than just the
combined filter effluent will generally
result in lower microbial risk, justify
1.0-log additional treatment credit.
c. Summary of Major Comments
Public comment on additional
treatment credit for individual filter
performance in the August 11, 2003
proposal raised a number of issues:
changes in the Partnership Phase IV
criteria and achievability of the
proposed criteria for this credit, credit
for participating in peer review
programs, and a review process for data
that exceed regulatory limit. A summary
of these comments and EPA's responses
follows.
Several commenters stated that PWSs
could not consistently achieve the
proposed individual filter effluent
turbidity criterion of 95 percent of daily
maximum measurements less than or
equal to 0.1 NTU. Commenters provided
data on turbidity levels in PWSs to
support this assertion and indicated that
the Partnership modified this criterion
in the Phase IV individual filter
performance goals because PWSs could
not meet it. Alternatives recommended
by commenters for the final rule
included the use of the revised
Partnership Phase IV goals for
individual filter effluent turbidity or a
more stringent criterion for combined
filter effluent turbidity.
In response, EPA agrees that current
Partnership Phase IV goals provide
appropriate criteria for awarding 1.0-log
total additional Cryptosporidium
treatment credit. Today's rule grants this
total credit to PWSs that meet a 95th
percentile individual filter effluent
turbidity limit of 0.15 NTU. and EPA
expects that PWSs complying with this
limit will operate under the Partnership
goal of 0.10 NTU. EPA does not support
awarding a higher level of additional
treatment credit for a more stringent
combined filter effluent turbidity
criterion, beyond the 0.5-log credit
available under combined filter
performance (see section IV.D.7). The
purpose of the individual filter
performance toolbox option is to
recognize the higher pathogen removal
PWSs will likely achieve by maintaining
very low effluent turbidity for each
individual filter.
A few commenters suggested that as
an alternative to establishing numerical
criteria for individual filter
performance, today's rule should award
additional treatment credit for PWSs
that successfully participate in a peer
review program. In addition to the
Partnership, commenters listed the Area
Wide Optimization Program and the
Texas Optimization Program as
examples of programs that will provide
for comprehensive improvements in
treatment performance.
EPA agrees that participation in peer
review programs is beneficial for PWSs.
Further, such programs may assist PWSs
in meeting the filtration performance
criteria in today's rule for additional
Cryptosporidium treatment credit. EPA
does not believe, however, that mere
participation in a peer review program
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is an appropriate basis for awarding
additional treatment credit. Rather, to
ensure national consistency in
standards for compliance with treatment
requirements, EPA has concluded that
additional treatment credit should be
based on PWSs meeting specified
criteria for enhanced treatment
performance.
Another significant issue raised by
commenters is the need for a review
process for deviations from the criteria
for individual filter performance due to
circumstances that cannot be prevented
through plant optimization. An example
given by several commenters is a filter
that malfunctions and is taken out of
service, but that may have exceeded the
individual filter performance turbidity
criteria for a short period when the filter
was operating.
EPA agrees that circumstances may
occur that are beyond the PWS's control
and that prevent the PWS from fully
meeting the criteria for individual filter
performance in a particular month. If a
PWS relies on individual filter
performance treatment credit to meet
the treatment requirements of today's
rule and the PWS fails to meet all
criteria for this credit in a given month,
the State may review the reasons for this
failure. If the State finds that the failure
was due to circumstances that could not
be prevented through plant
optimization, the State may choose not
to issue a treatment technique violation
on up to two such occasions in a
calendar year.
9. Demonstration of Performance
a. Today's Rule
A demonstration of performance is a
site-specific test that assesses the
Cryptosporidium removal efficiency of a
water treatment plant or a treatment
process within a plant. Under today's
rule, PWSs may undertake
demonstration of performance testing
for the following purposes:
(1) To establish a Cryptosporidium
treatment credit that is higher than the
proscribed treatment credit in today's rule for
a water treatment plant or a treatment
process in the microbial toolbox: or
(2) To establish a Cryptosporidium
treatment credit for a treatment process that
is not included in the microbial toolbox or
that does not meet the design or operational
criteria for prescribed treatment credit in the
microbial toolbox.
The specific requirements that apply
to demonstration of performance testing
are as follows:
• PWSs may receive Cryptosporidium
treatment credit for a water treatment
plant or a treatment process within a
plant that is based on a site-specific
demonstration of Cryptosporidium
removal efficiency. This demonstration
of performance treatment credit may be
greater than or less than any prescribed
treatment credit in today's rule.
• The site-specific demonstration of
Cryptosporidium removal efficiency
must follow a State-approved protocol
and may involve the use of surrogates
rather than Cryptosporidium.
• The State must approve through
written notification any treatment credit
based on a demonstration of
performance. As a condition of
approval, the State may designate
monitoring and treatment performance
criteria the PWS must meet and report
on an ongoing basis to remain eligible
for the credit. The State may designate
such criteria to verify that the PWS
maintains the operating conditions
under which the State approved the
demonstration of performance treatment
credit.
• PWSs are not eligible for prescribed
treatment credit for any treatment
process that is included in a
demonstration of performance credit.
b. Background and Analysis
The prescribed Cryptosporidium
treatment credits in today's rule for
water treatment plants and for treatment
processes in the microbial toolbox are
based on conservative estimates of mean
Cryptosporidium removal efficiencies.
Due to site-specific conditions,
however, some PWSs will achieve
greater Cryptosporidium removal than
reflected in the prescribed treatment
credits. In addition, some PWSs will
have treatment processes that are not
included in the microbial toolbox or
that do not meet microbial toolbox
criteria for prescribed treatment credit.
In all these cases, PWSs have the option
to undertake demonstration of
performance testing to establish an
appropriate level of Cryptosporidium
treatment credit for the treatment plant
or treatment process.
The option for demonstration of
performance testing in today's rule
reflects a recommendation by the Stage
2 M-DBP Advisory Committee.
Specifically, the Committee stated that
the LT2ESWTR should allow site-
specific testing both to establish
Cryptosporidium treatment credit above
the prescribed credit for microbial
toolbox processes and to demonstrate
Cryptosporidium removal for
technologies not listed in the microbial
toolbox. The August 11, 2003
LT2ESWTR proposal included the
demonstration of performance option
(USEPA 2003a), and EPA is establishing
it in today's final rule.
Demonstration of performance testing
will be specific to a particular site and
will depend on the treatment processes
being tested, water quality, plant
infrastructure, PWS resources, and other
factors. Consequently, today's rule does
not establish specific protocols for
demonstration of performance testing.
Rather, today's rule gives States the
authority to approve testing protocols
developed by PWSs and to determine
what level of Cryptosporidium
treatment credit is appropriate. The
Toolbox Guidance Manual provides
recommendations to PWSs and States
on conducting demonstration of
performance testing, including
analytical methods for measuring
aerobic and anaerobic spores.
In general, demonstration of
performance testing should encompass
the full range of expected operating
conditions and should conservatively
assess the degree of Cryptosporidium
removal that a treatment process can
reliably achieve. Directly quantifying
the removal of Cryptosporidium
typically is not feasible in full-scale
testing due to limitations in source
water concentrations and analytical
method performance. Consequently,
demonstration of performance testing
that is conducted at full-scale may
involve the use of surrogates, such as
aerobic spores, that have been shown to
correlate with the removal of
Cryptosporidium. PWSs and States may
also consider the use of pilot-scale
studies in conjunction with full-scale
studies for demonstration of
performance testing.
As a condition of approving a
demonstration of performance credit,
the State may designate treatment
performance criteria the PWS must meet
on an ongoing basis to remain eligible
for the credit. For example, if a PWS
conducts a demonstration of
performance study while operating with
very low filtered water turbidity, the
State may establish as a condition of
approving treatment credit based on the
study that the PWS must continue
operating at the low filtered water
turbidity. EPA believes this condition is
necessary because, in this example, if
the PWS were to begin operating at a
higher filtered water turbidity level, the
demonstration of performance study
results might no longer represent the
PWSs actual performance.
PWSs are not eligible for prescribed
treatment credit for any treatment
process that is included in a
demonstration of performance credit.
For example, if a PWS receives a
demonstration of performance treatment
credit of 4-log for Cryptosporidium
removal through a conventional
treatment plant (i.e., coagulation/
sedimentation/filtration), the PWS is not
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also eligible for additional treatment
credit for combined filter performance.
In this case, the demonstration of
performance testing accounts for the
removal achieved by filtration.
c. Summary of Major Comments
Public comment on the August 11,
2003 LT2ESWTR proposed supported
inclusion of the demonstration of
performance option to award site-
specific treatment credit to PWSs.
Commenters stated that many well-run
surface water treatment plants achieve
significantly greater Cryptosporidium
removal than the prescribed treatment
credit, and demonstration of
performance testing is needed to award
an appropriate level of credit in such
cases. Two aspects of this option that
received significant public comment are
the provision for States to award less
than the prescribed treatment credit if
indicated by testing results and the need
for guidance on demonstration of
performance testing. These comments
and EPA's responses are summarized as
follows.
Several commenters recommended
that EPA eliminate the provision that
allows States to award less than the
prescribed treatment credit based on
demonstration of performance testing.
These commenters stated that pilot- and
full-scale testing is conservative and
challenging to implement and that for
past regulations, States generally have
not awarded lower treatment credit
based on a site-specific study. If this
provision remains in the regulation,
commenters suggested that EPA provide
criteria addressing how it should be
applied. Such criteria should recognize
the conservative nature of testing with
surrogates for Cryptosporidium removal
and the potential for misleading or
flawed testing results.
In response, EPA believes that States
should have the discretion to award
either more or less treatment credit than
the prescribed credit on a case-by-case
basis where a State has site-specific
information that an alternative credit is
appropriate. Today's rule allows this.
EPA recognizes, however, that
demonstration of performance testing
should be designed to provide a
conservative estimate of treatment
efficiency and, as such, is not generally
intended to reduce the level of
treatment credit a PWS receives.
Further, results from demonstration of
performance testing should be
rigorously evaluated for flaws and bias
prior to being used to support either a
higher or lower treatment credit. The
Toolbox Guidance Manual identifies
approaches States may wish to consider
in awarding higher or lower treatment
credit.
Many commenters stated that EPA
should provide thorough guidance on
demonstration of performance testing.
Topics for this guidance suggested by
commenters include approaches to
demonstrating treatment credit,
minimum duration of testing, the use of
safety factors, and periodic
reconfirmation of testing results. Some
commenters recommended that
guidance address both full-scale testing
with surrogates like aerobic spores and
pilot-scale testing with Cryptosporidium
or surrogates. Other commenters
recommended that testing should be
limited to full-scale processes and that
testing with pilot-scale representations
of full-scale equipment should be
discouraged.
In the Toolbox Guidance Manual,
EPA provides direction on procedures
for demonstration of performance
testing that addresses issues raised by
commenters. These issues include
surrogates for full-scale testing,
potential roles for pilot-scale testing in
conjunction with full-scale testing,
minimum duration of testing to capture
the full range of operating conditions,
the analysis of data from testing to
establish treatment credit, and routine
monitoring to verify that the conditions
under which demonstration of
performance credit is awarded are
maintained during routine operation.
EPA believes that this guidance will
assist PWSs and States with
implementing demonstration of
performance testing appropriately.
10. Bag and Cartridge Filtration
a. Today's Rule
Under today's rule, PWSs may receive
Cryptosporidium treatment credit of up
to 2.0-log for an individual bag or
cartridge filter and up to 2.5-log for two
or more bag or cartridge filters operated
in series. To be eligible for this
treatment credit, filters must meet the
definition of a bag or cartridge filter and
must undergo challenge testing to
demonstrate removal efficiency with an
applied safety factor, as described in
this section.
Today's rule defines bag and cartridge
filters as pressure driven separation
processes that remove particulate matter
larger than 1 micrometer using an
engineered porous filtration media
through either surface or depth
filtration. Bag filters are constructed of
a non-rigid, fabric filtration media
housed in a pressure vessel in which the
direction of flow is from the inside of
the bag to the outside. Cartridge filters
are typically constructed as rigid or
semi-rigid, self-supporting filter
elements housed in a pressure vessel in
which flow is from the outside of the
cartridge to the inside.
Today's rule treats bag and cartridge
filters equivalently, with the following
exception: If a cartridge filter meets the
definition of a membrane filtration
process and can be direct integrity
tested according to the criteria specified
in section IV.D.ll, a PWS has the option
to seek greater treatment credit for the
filter as a membrane. Section IV.D.ll
describes criteria for awarding treatment
credit to membranes.
Today's rule requires challenge
testing to establish Cryptosporidium
treatment credit for bag and cartridge
filters. This challenge testing is product-
specific and not site-specific. Once
challenge testing is performed on a
specific bag or cartridge filtration
product, PWSs that install the specific
filtration product are not required to
repeat challenge testing at individual
sites. For a PWS to receive
Cryptosporidium treatment credit for a
bag or cartridge filter, challenge testing
must meet the following criteria:
• Challenge testing must be
conducted on full-scale filters that
match the filters the PWS will use in
materials, construction, and associated
housing or pressure vessel. If treatment
credit will be based on filters operated
in series then challenge testing must be
performed on the filters in series.
• Challenge testing must involve
measuring the removal by the filter of
either Cryptosporidium or a surrogate
that is removed no more efficiently than
Cryptosporidium (i.e., the "challenge
particulate").
• The analytical method used to
measure removal in the challenge test
must discretely quantify the specific
challenge particulate. The maximum
allowable feed water concentration of
the challenge particulate used during a
challenge test is 10,000 times the
analytical method detection limit of the
challenge particulate in the filtrate.
• During challenge testing, filters
must be operated at the maximum
design flow rate and for a duration
sufficient to reach the maximum design
pressure drop (i.e., "terminal pressure
drop"). PWSs may not operate bag or
cartridge filters outside of these design
parameters during routine use. In order
to achieve terminal pressure drop
during challenge testing, adding
particulate matter, such as fine carbon
test dust or bentonite clay particles, to
the test water is allowed and may be
necessary.
• In each challenge test, the removal
of the challenge particulate must be
measured during three periods over the
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filtration cycle: (1) Within two hours of
start-up of a new filter, (2] when the
pressure drop is between 45 and 55
percent of the terminal pressure drop,
and (3) when the pressure drop has
reached 100 percent of the terminal
pressure drop. A log removal value
(LRV) must be calculated for each of
these periods as follows: LOGi<> (filter
influent challenge particulate level) -
LOGio (filter effluent challenge
particulate level). For each filter tested,
the LRV for the filter (LRVmier) is equal
to the minimum of these three LRVs.
• The LRVflller values for each filter
that is tested are used to determine the
removal efficiency that is assigned to
the specific bag or cartridge filter
product (i.e., a filter product line) or
combination of filters in series. If fewer
than twenty filters are tested, the
removal efficiency of the filter product
line is equal to the lowest LRVf,llei
among the filters tested (today's rule
does not specify a minimum number of
filters to test). If twenty or more filters
are tested, the removal efficiency of the
filter product line is equal to the 10th
percentile of the LRVfn,,,, values among
the filters tested.
• The Cryptosporidium treatment
credit assigned to an individual bag or
cartridge filter is equal to the removal
efficiency established during challenge
testing minus a 1.0-log factor of safety,
up to a maximum treatment credit of
2.0-log (e.g., if challenge testing
demonstrates a removal efficiency of
3.0-log or greater, the filter is eligible to
receive 2.0-log Cryptosporidium
treatment credit).
• The Cryptosporidium treatment
credit assigned to configurations of two
or more bag or cartridge filters operated
in series is equal to the removal
efficiency established during challenge
testing minus a 0.5-log factor of safety,
up to a maximum treatment credit of
2.5-log (e.g., if challenge testing
demonstrates a removal efficiency of 3-
log or greater, the filter receives 2.5-log
Cryptosporidium treatment credit).
If a previously tested bag or cartridge
filter is modified in a manner that could
change the removal efficiency of the
filter product line, a new removal
efficiency must be established for the
modified filter through challenge
testing. If approved by the State, data
from challenge testing conducted prior
to promulgation of today's rule may be
considered in lieu of additional testing.
However, the prior testing must have
been conducted in a manner that
demonstrates a removal efficiency for
Cryptosporidium commensurate with
the treatment credit awarded to the
filter.
b. Background and Analysis
Bag and cartridge filters are widely
used by very small PWSs and in point-
of-entry applications to remove
particulate material from raw water,
including microbial pathogens like
Cryptosporidium. Depending on water
quality and treatment plant
infrastructure, these filters may be used
as the sole filtration step or as a
polishing filter that follows primary
filtration processes. A critical aspect of
bag and cartridge filters as defined in
today's rule is that they cannot undergo
direct integrity testing, which is used to
detect leaks that could result in
contamination of the treated water.
Cartridge filters that meet the definition
of a membrane process and can be direct
integrity tested are considered
membranes under today's rule, and
these are described in section IV.D.ll.
The Stage 2 M-DBP Advisory
Committee recommended
Cryptosporidium treatment credits of
1.0- and 2.0-log for bag and cartridge
filters, respectively (USEPA 2000a), and
the August 11, 2003 LT2ESWTR
proposal included criteria for PWSs to
receive these treatment credits. The
proposed criteria required challenge
testing and the application of a 1.0-log
factor of safety to establish treatment
credit. In today's final rule, EPA has
modified these criteria to allow both bag
and cartridge filters to be eligible for
2.0-log credit and to allow 2.5-log credit
with a 0.5-log factor of safety for bag or
cartridge filters operated in series. The
following discussion summarizes the
basis for these criteria and for
differences between the proposal and
today's final rule.
In the proposal, EPA reviewed bag
and cartridge filtration studies by Long
(1983), Schaub et al. (1993), Goodrich et
al. (1995), Ciardelli (1996a and 1996b),
Li et al. (1997). Roessler (1998),
Enriquez et al. (1999), NSF (2001a and
2001b), and Cornwell and LeChevallier
(2002). Results from these studies
indicated that both bag and cartridge
filters exhibit variable removal
efficiency, ranging from 0.5- to 3.6-log.
No correlation between the pore size
rating established by the manufacturer
and the removal efficiency of the filter
was apparent. Additionally, available
data did not indicate a strong
relationship between commonly used
process monitoring parameters, such as
turbidity and pressure drop, and
Cryptosporidium removal efficiency.
Due to this lack of correlation
between either design criteria or process
monitoring and removal efficiency,
today's rule requires challenge testing of
filters to establish Cryptosporidium
treatment credit. Challenge testing must
measure the removal across the filter of
Cryptosporidium or a surrogate, like
polystyrene microspheres, that is
removed no more efficiently than
Cryptosporidium (Long 1983, Li et al.
1997, NSF 2002b). Further, because
studies have shown the removal
efficiency of some bag and cartridge
filters to decrease over the course of a
filtration cycle (Li et al. 1997, NSF
2001a,b), challenge testing must assess
removal efficiency during three periods:
within two hours of startup of a new
filter, between 45-55 percent of
terminal pressure drop, and at the end
of the run after terminal pressure drop
is realized.
Bag and cartridge filter challenge
testing is product-specific and not site-
specific since the intent of this testing
is to demonstrate the removal
capabilities of the filtration device
rather than evaluate the feasibility of
implementing the technology at a
specific plant. Challenge testing must be
conducted using full-scale filter
elements to assess the performance of
the entire unit, including the filtration
media, seals, filter housing and other
components integral to the filtration
system. To be eligible for treatment
credit when operated in series, filters
must be tested in series. Multiple filters
of the same type can be tested to
provide a better statistical basis for
estimating removal efficiency. The
Toolbox Guidance Manual provides
information on bag and cartridge filter
challenge testing.
Today's rule establishes the proposed
requirement that a 1.0-log factor of
safety be applied to the removal
efficiency established during challenge
testing for individual bag or cartridge
filters when determining treatment
credit. Thus, to receive a 2.0-log
treatment credit, a removal efficiency of
at least 3.0-log must be demonstrated
during challenge testing. EPA believes
that this factor of safety is necessary
because integrity testing with bag and
cartridge filters is not possible (note:
under today's rule, cartridge filters that
can be integrity tested are classified as
membranes and no safety factor is
required; see section IV.D.ll).
Challenge testing provides an estimate
of the removal efficiency of a bag or
cartridge filter product line but does not
involve testing every filter. Further, it
does not fully capture the variation in
filter performance that will occur over
time during routine use. For
membranes, the use of direct integrity
tests, such as a pressure hold test, that
is correlated to removal efficiency
addresses this problem. With bag and
cartridge filters, however, EPA is aware
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of no equivalent test, and parameters
like turbidity and pressure differential
that may be monitored with these filters
have not been shown to correlate with
Cryptosporidium removal efficiency.
Consequently, a safety factor is
necessary to account for variation in
individual filter performance relative to
challenge test results.
Individual bag and cartridge filters are
eligible for a maximum
Cryptosporidium treatment credit of 2.0-
log. EPA proposed this level of credit for
cartridge filters but proposed a 1.0-log
maximum credit for bag filters, as
recommended by the Advisory
Committee. However, after further
reviewing available data, EPA has
concluded that treatment studies do not
support establishing different limits on
treatment credit for bag and cartridge
filters. Accordingly, today's rule treats
bag and cartridge filters equivalently.
EPA continues to believe that 2.0-log is
an appropriate maximum treatment
credit for a single bag or cartridge filter,
based on available data on the removal
of Cryptosporidium and surrogates by
these processes and the absence of a
direct integrity test.
Today's rule also establishes criteria
for awarding treatment credit to bag or
cartridge filters operated in series. EPA
believes that the use of these filters in
series provides clear advantages in
comparison to operation of a single
filter. Series operation will achieve both
greater removal efficiency and improved
reliability by lessening the impact of
variation in the performance of a single
filter. In consideration of these factors,
bag or cartridge filters operated in series
are eligible for a higher
Cryptosporidium treatment credit of 2.5-
log and require a lower safety factor of
0.5-log applied to challenge test results
when determining treatment credit.
c. Summary of Major Comments
In response to the August 11, 2003
proposal, EPA received significant
public comment on the following issues
related to bag and cartridge filtration:
the allowable treatment credit, the factor
of safety applied to challenge testing
results to determine treatment credit,
and the procedure for determining the
removal efficiency. A summary of these
comments and EPA's responses follows.
In regard to the proposed treatment
credits, several commenters
recommended that bag and cartridge
filters should be eligible for up to 2.0-
and 2.5-log credit, respectively, if
supported by the challenge test results.
Others commented that filters should be
allowed to qualify for removal credits at
or below the 1.0- and 2.0-log credits in
the proposal. EPA agrees that additional
flexibility should be provided with
respect to the removal credit awarded to
bag and cartridge filters. After reviewing
these comments and reassessing data
presented in the proposal on the
removal efficiencies of bag and cartridge
filters, EPA revised the proposal to
allow up to 2.0-log treatment credit for
either a single bag or cartridge filter. In
addition, today's rule allows up to 2.5-
log credit for bag or cartridge filters
operated in series.
With respect to the 1.0-log safety
factor applied to challenge test results to
determine treatment credit, some
commenters supported this approach,
while others recommended a reduced
safety factor. In response, EPA
continues to believe that a 1.0-log safety
factor is appropriate to address
variability in individual filter
performance and in the absence of a
direct integrity test for bag and cartridge
filters. Where filters are operated in
series, however, EPA agrees that the
safety factor should be reduced. Series
operation provides an intrinsic process
safety and will dampen some of the
variability in removal efficiency
observed for individual filters. Thus,
EPA is reducing the factor of safety to
0.5-log for configurations consisting of
two or more filters in series.
Commenters requested that EPA
clarify the procedure used to determine
the removal efficiency of bag and
cartridge filters. In response, expanded
and clarified guidance on conducting
challenge tests to determine removal
efficiency for bag and cartridge filters
has been included in the Toolbox
Guidance Manual.
11. Membrane Filtration
a. Today's Rule
Today's final rule establishes criteria
for awarding Cryptosporidium treatment
credit to membrane filtration processes.
To receive removal credit, filters must
meet the definition of a membrane
filtration process and undergo challenge
testing to establish removal efficiency;
PWSs must periodically verify system
integrity through direct integrity testing
and perform continuous indirect
integrity monitoring during use. The
removal credit awarded to a membrane
process is based on the removal
efficiency demonstrated during
challenge testing and the sensitivity of
the direct integrity test.
For the purpose of today's rule,
membrane filtration is defined as a
pressure or vacuum driven separation
process in which particulate matter
larger than 1 micrometer is rejected by
an engineered barrier, primarily through
a size-exclusion mechanism, and which
has a measurable removal efficiency of
a target organism that can be verified
through the application of a direct
integrity test.
Membrane Challenge Testing
Any membrane filter used to meet the
treatment requirements of today's rule
must undergo challenge testing to
determine its Cryptosporidium removal
efficiency. Challenge testing establishes
the maximum Cryptosporidium
treatment credit a membrane filtration
process is eligible to receive, provided
this value is less than or equal to the
sensitivity of the direct integrity test, as
described later in this section. Challenge
testing for membranes is product-
specific, and PWSs that install
membranes that have successfully
undergone challenge testing are not
required to repeat testing at their sites.
Membrane challenge testing must meet
the following criteria:
• Challenge testing must be
conducted on either an identical full-
scale module or a smaller-scale module
identical in material and similar in
construction to the membrane modules
the PWS will use. A module is the
smallest component of a membrane unit
in which a specific membrane surface
area is housed in a device with a filtrate
outlet structure.
• Either Cryptosporidium or a
surrogate that is removed no more
efficiently than Cryptosporidium must
be used as the challenge particulate
during challenge testing.
• The analytical method used to
measure removal in the challenge test
must discretely quantify the specific
challenge particulate. The maximum
allowable feed water concentration used
during a challenge test is 6.5-log (3.16
x I0h) times the detection limit of the
challenge particulate in the filtrate.
• Challenge testing must be
conducted under representative
hydraulic conditions at the maximnm
design flux and maximum design
process recovery as specified by the
manufacturer for the membrane
filtration process. Flux is defined as the
throughput of a pressure driven
membrane process expressed as flow
per unit of membrane area. Recovery is
defined as the volumetric percent of
feed water that is converted to filtrate
over the course of an operating cycle
uninterrupted by events such as
chemical cleaning or a solids removal
process (i.e., backwashing).
• The removal efficiency for the
membrane is determined from the
results of the challenge test, expressed
as a log removal value (LRV). A LRV
must be calculated for each membrane
module evaluated during the challenge
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703
test based on the feed and filtrate
concentrations of the challenge
particulate for that module. The
individual LRVs for each module are
used to determine the overall removal
efficiency of the membrane product. If
fewer than twenty modules are tested,
the overall removal efficiency is
assigned a value equal to the lowest of
the representative LRVs for the various
modules tested. If twenty or more
modules are tested, then the overall
removal efficiency is assigned a value
equal to the 10th percentile of the
representative LRVs for the various
modules tested.
• As part of the challenge test, a
quality control release value (QCRV)
must be established for a non-
destructive performance test (e.g.,
bubble point test, diffusive airflow test,
pressure/vacuum decay test) that
demonstrates the Cryptosporidium
removal capability of the membrane
module. The non-destructive
performance test must be applied to
each membrane module a PWS uses in
order to verify Cryptosporidium
removal capability. Membrane modules
that do not meet the established QCRV
are not eligible for the Cryptosporidium
removal credit demonstrated during
challenge testing.
If a previously tested membrane
product is modified in a manner that
could change the removal efficiency of
the membrane or the applicability of
non-destructive performance test and
associated QCRV, the modified
membrane filter must be challenge
tested to establish the removal
efficiency and QCRV. If approved by the
State, data from challenge testing
conducted prior to promulgation of
today's rule may be considered in lieu
of additional testing. However, the prior
testing must have been conducted in a
manner that demonstrates a removal
efficiency for Cryptosporidium
commensurate with the treatment credit
awarded to the filter.
Membrane Direct Integrity Testing
In order to receive Cryptosporidium
treatment credit for a membrane
filtration process, PWSs must conduct
direct integrity testing in a manner that
demonstrates a removal efficiency equal
to or greater than the removal credit
awarded to the membrane filtration
process. A direct integrity test is defined
as a physical test applied to a membrane
unit in order to identify and isolate
integrity breaches (i.e., one or more
leaks that could result in contamination
of the filtrate).
Each membrane unit must be
independently direct integrity tested,
where a membrane unit is defined as a
group of membrane modules that share
common valving which allows the unit
to be isolated from the rest of the system
for the purpose of integrity testing or
other maintenance. The direct integrity
test must be applied to the physical
elements of the entire membrane unit
including membranes, seals, potting
material, associated valving and piping,
and all other components which under
compromised conditions could result in
contamination of the filtrate.
Common direct integrity tests include
those that apply pressure or vacuum
(such as the pressure decay test and
diffusive airflow test) and those that
measure the rejection of a particulate or
molecular marker (such as spiked
particle monitoring). Today's final rule
does not stipulate the use of a particular
direct integrity test. Instead, the direct
integrity test must meet performance
criteria for resolution, sensitivity, and
frequency.
"Resolution" is defined as the
smallest leak that contributes to the
response from a direct integrity test.
Any direct integrity test applied to meet
the requirements of this rule must have
a resolution of 3 micrometers or less.
The manner in which resolution is
determined will depend on the type of
direct integrity test used (i.e., pressure-
based versus marker-based tests).
"Sensitivity" is defined as the
maximum LRV that can be reliably
verified by the direct integrity test. The
sensitivity of the direct integrity test
applied to a membrane filtration process
to meet the Cryptosporidium treatment
requirements of this rule must be equal
to or greater than the removal credit
awarded to the membrane filtration
process. Furthermore, the increased
concentration of suspended solids that
occurs on the high pressure side of the
membrane in some module designs
must be considered in the sensitivity
determination (i.e., the scouring action
of some membrane designs keeps the
accumulated solids in suspension where
they may pass through an integrity
breach). Specifically, the sensitivity of
the direct integrity test is reduced by a
factor that quantifies the increased
concentration of suspended solids
relative to the feed concentration.
The "frequency" of direct integrity
testing specifies how often the test is
performed over an established time
interval. Direct integrity tests available
at the time of promulgation are applied
periodically and must be conducted on
each membrane unit at a frequency of
not less than once per day that the unit
is in operation, unless the State
determines that less frequent testing is
acceptable. If continuous direct integrity
test methods become available that also
meet the sensitivity and resolution
criteria described earlier, such a
continuous test may be used in lieu of
periodic testing.
PWSs must establish a direct integrity
test control limit that is indicative of an
integral membrane unit capable of
meeting the Cryptosporidium removal
credit awarded to the membrane. If the
control limit for the direct integrity test
is exceeded, the membrane unit must be
taken off-line for diagnostic testing and
repair. The membrane unit may only be
returned to service after the repair has
been completed and confirmed through
the application of a direct integrity test.
A monthly report must be submitted to
the State summarizing all direct
integrity test results above the control
limit and the corrective action that was
taken in each case.
Continuous Indirect Integrity Monitoring
Available direct integrity test methods
are applied periodically since the
membrane unit must be taken out of
service to conduct the test. In order to
provide some measure of process
performance between direct integrity
testing events, PWSs must perform
continuous indirect integrity monitoring
on each membrane unit. Continuous
indirect integrity monitoring is defined
as monitoring some aspect of filtrate
water quality that is indicative of the
removal of particulate matter at a
frequency of at least once every 15
minutes. If a continuous direct integrity
test is implemented that meets the
resolution and sensitivity criteria
described previously in this section,
continuous indirect integrity monitoring
is not required.
Unless the State approves an
alternative parameter, continuous
indirect integrity monitoring must
include continuous filtrate turbidity
monitoring. If the filtrate turbidity
readings are above 0.15 NTU for a
period greater than 15 minutes, the PWS
must perform direct integrity testing on
the associated membrane unit.
If the State approves an alternate
parameter for continuous indirect
integrity monitoring, the State must
approve a control limit for that
parameter. If the parameter exceeds the
control limit for a period greater than 15
minutes, the PWS must perform direct
integrity testing on the associated
membrane unit.
PWSs must submit a monthly report
to the State summarizing all continuous
indirect integrity monitoring results
triggering direct integrity testing and the
corrective action that was taken in each
case.
EPA has developed the Membrane
Filtration Guidance Manual to assist
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systems with implementation of these
requirements. This guidance may be
requested from EPA's Safe Drinking
Water Hotline, which may be contacted
as described under FOR FURTHER
INFORMATION CONTACT in the beginning
of this notice.
b. Background and Analysis
In the August 11, 2003 proposed
LT2ESWTR, EPA proposed to establish
criteria for awarding credit to membrane
filtration processes for removal of
Cryptosporidium (USEPA 2003g). The
Agency based these criteria on data
demonstrating the Cryptosporidium
removal efficiency of membrane
filtration processes, a critical evaluation
of available integrity monitoring
techniques, and study of State
approaches to the regulation of
membrane filtration for pathogen
removal. This information is
summarized in the report Low-Pressure
Membrane Filtration for Pathogen
Removal: Application, Implementation,
and Regulatory Issues (USEPA 2001g).
As summarized in this report, a
number of studies demonstrate the
ability of membrane filtration processes
to remove pathogens, including
Cryptosporidium, to below detection
levels (USEPA 2001g). In some studies
that used Cryptosporidium seeding,
measured removal efficiencies were as
high as 7-log (Jacangelo, et al., 1997;
Hagen, 1998; Kachalsky and Masterson,
1993). In other studies, removal
efficiencies ranged from 4.4- to 6.5-log
and were only limited by the seeded
concentration of Cryptosporidium
oocysts (Dwyer, et al. 1995, Jacangelo et
al. 1989, Trussel, et al. 1998, NSF
2000a-g, Olivieri 1989). Collectively,
these results demonstrate that an
integral membrane module (i.e., a
membrane module without any leaks or
defects, with an exclusion characteristic
smaller than Cryptosporidium) is
capable of removing this pathogen to
below detection in the filtrate,
independent of the influent
concentration.
The 2003 proposal included a
provision for challenge testing
membranes to demonstrate the removal
efficiency of Cryptosporidium. EPA
believes this requirement is necessary
due to the proprietary nature of these
products and the lack of any uniform
design criteria for establishing the
exclusion characteristic of a membrane.
Guidance on the design and conduct of
a challenge test to meet the
requirements of this rule is presented in
the Membrane Filtration Guidance
Manual.
Challenge testing is required on a
product-specific basis, rather than a site-
specific basis; thus, modules used in
full-scale facilities will generally not be
directly challenge tested. The removal
capability of production membrane
modules is verified through the
application of a non-destructive
performance test, such as a bubble point
test. A quality control release value
(QCRV) for the non-destructive
performance test can be related to the
results of the challenge test and used to
demonstrate the ability of production
modules to achieve the
Cryptosporidium removal efficiency
demonstrated during challenge testing.
Most membrane manufacturers have
adapted some form of non-destructive
testing for the purpose of product
quality control and have established a
QCRV that is indicative of an acceptable
product. It may be possible to apply
these existing practices to meet the
requirements of today's final rule.
While challenge testing demonstrates
the removal efficiency of an integral
membrane module, defects or leaks in
the membrane or other system
components can result in contamination
of the filtrate unless they are identified,
isolated, and repaired. In order to verify
continued performance of a membrane
system, today's final rule requires direct
integrity testing of membrane filtration
processes used to meet the
Cryptosporidium treatment
requirements of this rule.
An evaluation of available direct
integrity tests indicates that pressure-
based tests are widely applied and
sufficiently sensitive to provide
verification of removal efficiencies in
excess of 4-log. Marker-based direct
integrity tests are also available, and
new direct integrity tests may be
developed that present an improvement
over existing tests. Rather than specify
a particular direct integrity test, today's
final rule defines performance criteria
for direct integrity testing. These criteria
are resolution, sensitivity, and
frequency, as previously described. EPA
believes that this approach will provide
flexibility for the development and
implementation of future innovations in
direct integrity testing while ensuring
that any test applied to meet the
requirements of this rule will achieve
the required level of performance.
Since available direct integrity tests
require taking the membrane unit out of
service to conduct the test, today's rule
establishes a minimum test frequency
for direct integrity testing. Currently,
there is no standard frequency for direct
integrity testing that has been adopted
by all States and membrane treatment
facilities. In a 2000 survey, the required
frequency of integrity testing was found
to vary from once every four hours to
once per week; however, the most
common frequency for conducting a
direct integrity test was once every 24
hours (USEPA 2001g). Specifically, 10
out of 14 States that require periodic
direct integrity testing specify a
frequency of once per day. Furthermore,
many membrane manufacturers of
systems with automated integrity test
systems set up the membrane units to
automatical^' perform a direct integrity
test once per day.
EPA believes that daily direct
integrity testing is appropriate for most
membrane filtration installations, but
under some circumstances, less frequent
testing may be adequate. Thus, EPA is
allowing States to approve less frequent
direct integrity testing on the basis of
demonstrated process reliability, use of
multiple barriers effective for
Cryptosporidium, or reliable process
safeguards.
Due to the periodic nature of direct
integrity testing, today's rule includes a
provision for continuous indirect
integrity monitoring. While indirect
monitoring is not as sensitive as direct
testing, it provides an indication of
process performance to ensure that a
major failure has not occurred between
application of direct integrity tests.
c. Summary of Major Comments
In response to the 2003 proposal, the
Agency received significant comments
on the following issues related to
membrane filtration: the frequency of
direct integrity testing; the procedure
necessary to determine removal credit
for membrane filtration; and the
requirement for continuous indirect
integrity monitoring.
The 2003 proposal requested
comment on the proposed minimum
direct integrity test frequency of once
per day. Some commenters supported
the daily frequency and commented that
many states have already adopted this
standard. Others commented that direct
integrity testing once per day is too
frequent, citing the lack of data in the
proposal documenting the rate of
membrane failure, as well as the loss in
production that occurs when the
membrane unit is taken off-line for
testing.
While EPA recognizes these concerns,
a critical factor in establishing a testing
frequency is the amount of time that
water from a compromised membrane
unit is supplied to the public before the
integrity breach is detected. EPA
believes that this factor is most
important to public health protection
and that daily direct integrity testing is
appropriate for the majority of
membrane systems. However, EPA also
acknowledges that there may be
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705
circumstances under which less
frequent testing may provide adequate
public health protection, and has
revised the rule to allow States to permit
less frequent direct integrity testing
based on demonstrated process
reliability, use of multiple barriers
effective for Cryptosporidium, or
reliable process safeguards.
Several commenters expressed
concern with the process needed to
determine appropriate removal credit
for membrane filtration. However, many
commenters also supported the
flexibility provided to States in
determining the appropriate removal
credit for membrane filtration based on
the criteria defined in the 2003
proposal. EPA believes that the
proposed approach for awarding
Cryptosporidium removal credit to
membrane filtration is supported by the
available data and analysis, and will
allow higher removal credits to be
considered on a scientifically sound
basis. EPA recognizes that the flexibility
provided in the regulation does increase
the complexity of determining removal
credits for membrane filtration. To
address this issue, EPA has developed
extensive guidance to support the
implementation of requirements for
membrane filtration.
EPA received comment that
continuous indirect integrity monitoring
is unnecessary due to the poor
sensitivity of currently available
methods. EPA acknowledges that
currently available indirect monitoring
methods are less sensitive than available
direct integrity tests. However, EPA
believes that continuous indirect
integrity monitoring is necessary to
protect public health. Specifically,
continuous monitoring may alert a
system of potentially severe integrity
breaches that could result in bypass of
unfiltered water around the membrane
filtration process and pose a risk to
public health. Furthermore, EPA has
provided States with the flexibility to
permit use of more sensitive continuous
indirect monitoring methods and/or to
establish lower control limits. Also,
implementation of continuous direct
integrity testing would preclude the
need to implement any form of indirect
integrity monitoring.
12. Second Stage Filtration
a. Today's Rule
PWSs may receive 0.5-log credit
towards the Cryptosporidium treatment
requirements of today's rule for a
second filtration stage. To be eligible for
this credit, the second-stage filtration
must meet the following criteria:
• The filter must be a separate second
stage of granular media filtration, such
as sand, dual media, or granular
activated carbon (GAG), that follows a
first stage of granular media filtration
(e.g., follows a conventional treatment
or direct filtration plant).
• The first filtration stage must be
preceded by a coagulation process.
• Both filtration stages must treat 100
percent of the treatment plant flow.
• The State must approve the
treatment credit based on an assessment
of the design characteristics of the
filtration process.
This microbial toolbox option does
not apply to bag filters, cartridge filters,
membranes, or slow sand filters, which
are addressed separately in the
microbial toolbox. Further, this options
does not apply to roughing filters,
which are pretreatment processes that
typically consist of coarse media and are
not preceded by coagulation. States may
consider awarding treatment credit to
roughing filters under a demonstration
of performance.
PWSs may not receive additional
treatment credit for both second-stage
filtration and lower filter effluent
turbidity (i.e., combined or individual
filter performance) that is based on
turbidity levels following the second
filtration stage. PWSs may receive credit
for both options based on turbidity
following the first filtration stage.
b. Background and Analysis
The Stage 2 M-DBP Advisory
Committee recommended a 0.5-log
Cryptosporidium treatment credit for a
roughing filter with the stipulation that
EPA identify the design and operational
conditions under which such credit is
appropriate. After reviewing available
data; however, EPA was unable to
determine conditions under which a
roughing filter is likely to achieve at
least 0.5-log removal of
Cryptosporidium. Roughing filters
consist of coarse media like gravel and
usually are not preceded by coagulation.
They are used to remove sediment and
large particulate matter from raw water
prior to the primary treatment
processes. EPA identified no studies
indicating that roughing filters would be
effective for removal of
Cryptosporidium (USEPA 2003a).
In contrast, numerous studies have
demonstrated that granular media
filtration can be effective for removing
Cryptosporidium when preceded by
coagulation (Patania et al. 1995,
Nieminski and Ongerth 1995, Ongerth
and Pecoraro 1995, LeChevallier and
Norton 1992, LeChevallier et al. 1991,
Dugan et al. 2001, Nieminski and
Bellamy 2000, McTigue et al. 1998,
Patania et al. 1999, Huck et al. 2000,
Emelko et al. 2000). PWSs may
implement a second granular media
filtration stage to achieve various water
quality objectives, such as increased
removal of organic material in
biologically active filters or removal of
inorganic contaminants. Consequently,
EPA believes that consideration of
additional Cryptosporidium treatment
credit for a second granular media
filtration stage is appropriate.
The August 11, 2003 LT2ESWTR
proposal included an additional 0.5-log
Cryptosporidium treatment credit for
PWSs that use a second separate
filtration stage consisting of rapid sand,
dual media, GAC, or other fine grain
media. A cap, such as GAC, on a single
stage of filtration did not qualify. In
addition, the proposal required the first
stage of filtration to be preceded by a
coagulation step and both stages had to
treat 100 percent of the plant flow.
Today's final rule establishes this
treatment credit with minimal changes
from the proposal. The basis for this
credit and for changes from the
proposed rule are summarized in the
following discussion.
While the studies of Cryptosporidium
removal by granular media filtration
cited previously evaluated only a single
stage of filtration, the same removal
mechanisms will be operative in a
second stage of granular media
filtration. Secondary filters may remove
Cryptosporidium that were destabilized
but not trapped in primary filters or that
were trapped but subsequently detached
from primary filters prior to backwash.
Thus, EPA believes these studies are
supportive of additional removal credit
for a second filtration stage.
An important finding of these studies
is that coagulation is necessary to
achieve significant Cryptosporidium
removal by granular media filtration
(does not apply to slow sand filtration,
which is addressed in the next section).
Consequently, today's rule requires that
the first filtration stage be preceded by
coagulation for a PWS to receive
treatment credit for second-stage
filtration. This requirement is necessary
to ensure that both filtration stages are
effective for Cryptosporidium removal.
PWSs will already comply with this
requirement where a second filtration
stage is applied after conventional
treatment or direct filtration.
In the proposal, EPA also reviewed
data provided by a PWS on the removal
of aerobic spores through GAC filters
(i.e., contactors) following conventional
treatment. As discussed earlier, studies
have demonstrated that aerobic spores
can serve as an indicator of
Cryptosporidium removal by granular
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media filtration (Dugan et al. 2001,
Emelko et al. 1999 and 2000, Yates et al.
1998, Mazounie et al. 2000). Over a two
year period, the mean removal of
aerobic spores across the GAG filters
exceeded 0.5-log. These results support
the finding that a second stage of
granular media filtration can reduce
Cryptosporidium levels by 0.5-log or
greater.
Today's rule does not establish design
criteria such as filter depth or media
size for second-stage filters to be eligible
for treatment credit. While filter design
will influence Cryptosporidium removal
efficiency, EPA recognizes that
appropriate filter designs will vary
depending on the application. States
have traditionally provided oversight for
treatment process designs in PWSs.
Accordingly, today's rule requires State
review and approval of second-stage
filter design as a condition for PWSs to
receive additional treatment credit for
this process. The Microbial Toolbox
Guidance Manual addresses second-
stage filtration for Cryptosporidium
treatment credit.
c. Summary of Major Comments
Public comment on the August 11,
2003 LT2ESWTR proposal generally
supported additional treatment credit
for second-stage filtration. Commenters
raised specific concerns with EPA
establishing design requirements for
filtration, the sufficiency of data to
support prescribed treatment credit, and
the expansion of this credit to include
other filtration technologies. These
comments and EPA's responses are
summarized as follows.
In the proposal, EPA requested
comment on whether a minimum filter
depth should be required for PWSs to
receive treatment credit for a second
filtration stage. All commenters opposed
EPA setting regulatory design standards
for filters on the basis that PWSs and
States need the flexibility to determine
appropriate treatment designs. In
response, EPA agrees that effective filter
designs will vary depending on the
application. Consequently, EPA is not
establishing filter design criteria in
today's rule, but is requiring that States
approve designs for PWSs to receive
treatment credit for second-stage
filtration.
Many commenters stated that
available data support the prescribed
0.5-log Cryptosporidium treatment
credit for second-stage filtration. Some
commenters provided additional data
on the removal of aerobic spores
through GAG filters following
conventional treatment that showed a
mean reduction greater than 1-log. In
contrast, other commenters were
concerned about the lack of data to
support increased removal through a
second filtration stage. These
commenters recommended that
treatment credit for second-stage
filtration should be awarded only on a
site-specific basis through a
demonstration of performance.
EPA has concluded that available data
are sufficient to support the prescribed
0.5-log treatment credit for second-stage
filtration. Studies of granular media
filtration demonstrate high levels of
Cryptosporidium removal and one study
has shown greater than 1.0-log removal
through secondary GAG filters.
Secondary filters can remove
Cryptosporidium that pass through or
detach from the primary filters. This
added removal will help to stabilize
finished water quality by providing a
barrier during periods of the filtration
cycle when the primary filters are not
performing optimally. Therefore, EPA is
establishing this credit in today's rule.
Several commenters recommended
that EPA expand the second-stage
filtration option to include membranes,
bag filters, and DE filtration. EPA notes
that today's rule establishes prescribed
treatment credits specifically for bag
and cartridge filters and membranes as
microbial toolbox options, and
prescribed credit for DE filtration is
addressed in section IV.B. PWSs may
seek treatment credit for other filtration
technologies through a demonstration of
performance under today's rule.
13. Slow Sand Filtration
a. Today's Rule
PWSs may receive a 2.5-log credit
towards the Cryptosporidium treatment
requirements in today's rule for
implementing slow sand filtration as a
secondary filtration stage following a
primary filtration process. To be eligible
for this credit, the slow sand filtration
must meet the following criteria:
• The slow sand filter must be a
separate second stage of filtration that
follows a first stage of filtration like
conventional treatment or direct
filtration;
• There must be no disinfectant
residual in the influent water to the
slow sand filtration process;
• Both filtration stages must treat 100
percent of the treatment plant flow from
a surface water or GWUDI source: and
• The State must approve the
treatment credit based on an assessment
of the design characteristics of the
filtration process.
Slow sand filtration used as a primary
filtration process receives a prescribed
3-log Cryptosporidium treatment credit,
as described in section IV.B.
b. Background and Analysis
Slow sand filtration is a process
involving passage of raw water through
a bed of sand at low velocity (generally
less than 0.4 m/h), resulting in
substantial particulate removal. Several
studies have demonstrated that slow
sand filtration can achieve significant
Cryptosporidium removal (Schuler and
Ghosh, 1991, Timms et al. 1995, Hall et
al. 1994). Slow sand filtration is
typically used as a primary filtration
process, usually in small systems, rather
than as a secondary filtration stage
following conventional treatment or
another primary filtration process. EPA
expects, however, that slow sand
filtration would be effective for
Cryptosporidium removal in such an
application, which warrants
consideration of treatment credit under
today's rule.
The Stage 2 M-DBP Advisory
Committee recommended that slow
sand filtration receive 2.5-log or greater
Cryptosporidium treatment credit when
used in addition to existing treatment
that achieves compliance with the
IESWTR or LT1ESWTR. The August 11,
2003 LT2ESWTR proposal included 2.5-
log treatment credit for slow sand as a
secondary filtration process, with the
only associated condition being no
disinfectant residual in the water
influent to the filter. In today's rule,
EPA is establishing this treatment credit
with minimal changes from the
proposal. The following discussion
summarizes the basis for this credit and
for changes from the proposal.
Removal of microbial pathogens in
slow sand filters is complex and is
believed to occur through a combination
of physical, chemical, and biological
mechanisms, both on the surface and in
the interior of the filter bed. In
particular, biological activity in the
upper layers of the filter is believed to
promote microbial removal. Based on
previously cited studies demonstrating
greater than 4-log removal of
Cryptosporidium through slow sand
filtration, today's rule awards a
prescribed 3-log Cryptosporidium
removal credit to slow sand filtration as
a primary filtration process.
The effectiveness of slow sand as a
secondary filtration process is more
uncertain. In general, EPA expects that
the same microbial removal
mechanisms will be operative. However,
due to the quality of treated water
following a primary filtration process,
filter ripening and development of the
biologically active layer in a secondary
slow sand filter may be inhibited. One
study that evaluated Cryptosporidium
removal by slow sand filtration alone
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707
and slow sand filtration preceded by a
rapid sand filter observed similar
removal levels in the two treatment
trains (Hall et al. 1994). Because of the
uncertainty regarding the performance
of slow sand as a secondary filtration
step and in consideration of the
Advisory Committee recommendation,
today's rule establishes a 2.5-log
additional Cryptosporidium treatment
credit for this application.
Due to the importance of biological
activity to slow sand filter performance,
PWSs may not receive the prescribed
treatment credit if the influent water to
the slow sand filter contains a
disinfectant residual. EPA is not
establishing design standards for slow
sand filters in today's rule. Studies have
shown, however, that design
deficiencies in slow sand filters may
lead to poor Cryptosporidium removal
(Fogel et al. 1993). Consequently, States
must approve slow sand filter designs as
a secondary filtration stage for PWSs to
receive treatment credit under today's
rule.
c. Summary of Major Comments
Public comment on the August 11,
2003 proposal focused on the question
of whether the 2.5-log Cryptosporidium
treatment credit for slow sand as a
secondary filtration process is
appropriate. Many commenters
supported the proposed treatment
credit. These commenters cited studies
demonstrating greater than 4-log
Cryptosporidium removal by slow sand
filtration and concluded that the data
justify a 2.5-log treatment credit for slow
sand filtration added to a clarification
and filtration treatment train.
Several commenters, however, stated
that this treatment credit is not justified
due to the lack of data on the
performance of slow sand as a
secondary filtration step. Available
studies on slow sand filter performance
for Cryptosporidium removal have
mostly been conducted on raw (i.e.,
unfiltered) water. These commenters
were concerned that if slow sand
filtration is applied following a primary
filtration process, the filter ripening
period and other factors will be
significantly affected. As a result, the
slow sand filtration may provide only
limited removal over a long ripening
period.
In response, EPA recognizes that little
testing has been conducted on the
performance of slow sand filtration
specifically as a second filtration stage
in a treatment train. However, available
data do not indicate that slow sand
filtration would be substantially less
effective when used in this capacity.
Slow sand filtration is recommended
only for higher quality source waters,
and water quality following a primary
filtration process would be well within
recommended design limits for slow
sand filtration (USEPA 1991a). EPA
agrees that filter ripening is critical to
slow sand filtration achieving its full
performance level, and this process may
require more time when slow sand
filtration follows a primary filtration
process. However, this effect may be
counterbalanced by very long filter run
times between cleaning the filter due to
the high quality influent water.
Consequently, EPA believes that 2.5-log
Cryptosporidium treatment credit for
slow sand as a secondary filtration
process is warranted.
14. Ozone and Chlorine Dioxide
a. Today's Rule
PWSs may use ozone and chlorine
dioxide to meet Cryptosporidium
treatment requirements under today's
rule. To receive treatment credit, PWSs
must measure the water temperature,
disinfectant contact time, and residual
disinfectant concentration at least once
each day and determine the log
inactivation credit using the tables in
this section. Specific criteria are as
follows:
• The temperature of the disinfected
water must be measured at least once
per day at each residual disinfectant
concentration sampling point.
• The disinfectant contact time(s)
("t") must be determined for each day
during peak hourly flow.
• The residual disinfectant
concentration(s) ("C") of the water
before or at the first customer must be
measured each day during peak hourly
flow.
• Tables IV.D-3 or IV.D-4 must be
used to determine Cryptosporidium log
inactivation credit for ozone or chlorine
dioxide, respectively, based on the
water temperature and the product of
disinfectant concentration and contact
time (CT).
TABLE IV.D-3.
VALUES FOR CRYPTOSPORIDIUM INACTIVATION BY OZONE 1 (MG/L x MIN)
Log credit
025
0 5
1 0
1 5
20
25
30
Water temperature, °C
<0.5
60
12
24
36
48
60
72
1
5.8
12
23
35
46
58
69
2
5.2
10
21
31
42
52
63
3
4.8
9.5
19
29
38
48
57
5
40
7.9
16
24
32
40
47
7
3.3
6.5
13
20
26
33
39
10
2.5
4.9
9.9
15
20
25
30
15
1 6
3.1
6.2
9.3
12
16
19
20
1.0
2.0
3.9
5.9
7.8
9.8
12
25
0.6
1.2
2.5
3.7
4.9
6.2
74
30
0.39
0.78
1 6
2.4
31
3.9
4.7
' PWSs may use this equation to determine log credit between the indicated values. Log credit = (0.0397 x (1.09757) le™p) x CT.
TABLE IV.D-4.—CT VALUES FOR CRYPTOSPORIDIUM INACTIVATION BY CHLORINE DIOXIDE 1 (MG/L x MIN)
Log credit
025
05
1 0
1 5
20
2.5 ..
3.0
Water temperature, °C
<0.5
159
319
637
956
1275
1594
1912
1 2
153
305
610
915
1220
1525
1830
140
279
558
838
1117
1396
1675
3
128
256
511
767
1023
1278
1534
5
107
214
429
643
858
1072
1286
7
90
180
360
539
719
899
1079
10
69
138
277
415
553
691
830
15
45
89
179
268
357
447
536
20
29
58
116
174
232
289
347
25
19
38
75
113
150
188
226
30
12
24
49
"73
98
122
147
1 PWSs may use this equation to determine log credit between the indicated values: Log credit = (0.001506 x (1.09116)Temp) x CT.
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PWSs may have several disinfection
segments in sequence along the
treatment train, where a disinfectant
segment is defined as a treatment unit
process with a measurable disinfectant
residual level and a liquid volume. In
determining the total log inactivation,
the PWS may calculate the CT for each
disinfection segment and use the sum of
these values to determine the log
inactivation achieved through the plant.
The Toolbox Guidance Manual provides
information on recommended •
methodologies for determining CT
values for different disinfection reactor
designs and operations.
Alternatively, the State may approve
alternative CT values to those specified
in Tables IV.D-3 or IV.D-4 based on a
site-specific study a PWSs conducts
following a State-approved protocol.
The Toolbox Guidance Manual
describes recommended approaches for
making such demonstrations.
b. Background and Analysis
Ozone and chlorine dioxide are
chemical disinfectants that have been
shown to be effective for inactivating
Cryptosporidium. The Stage 2 M-DBP
Advisory Committee recommended that
EPA develop criteria for PWSs to
achieve Cryptosporidium inactivation
credit with these disinfectants. The
August 11, 2003 LT2ESWTR proposal
included CT values for 0.5- to 3-log
Cryptosporidium inactivation credit by
ozone or chlorine dioxide at
temperatures ranging from less than 0.5
C to 25 C, along with daily required
monitoring (USEPA 2003a). Today's
final rule establishes these criteria with
no changes from the proposed rule, but
expands the CT tables down to 0.25-log
inactivation and up to a water
temperature of 30 C. The following
discussion summarizes the basis for
these criteria.
The requirements for at least daily
monitoring of the water temperature,
residual disinfectant concentration, and
contact time during peak hourly flow to
determine a daily inactivation level
reflect existing requirements for Giardia
inactivation by chemical disinfection in
40 CFR 141.74. EPA expects that in
practice, many PWSs using ozone or
chlorine dioxide will monitor more
frequently and for multiple disinfectant
segments. In the Toolbox Guidance
Manual, EPA provides information on
recommended approaches for
monitoring and calculating CT values
for ozone and chlorine dioxide reactors.
The CT values for both ozone and
chlorine dioxide are based on analyses
by Clark et al. (2002a,b), with additional
procedures to assess confidence bounds.
Clark et al. (2002a,b) developed
predictive equations for
Cryptosporidium inactivation through
evaluating studies on ozone by
Rennecker et al. (1999), Li et al. (2001),
Owens et al. (2000). and Oppenheimer
et al. (2000) and on chlorine dioxide by
Li et al. (2001), Owens et al. (1999) and
Ruffell et al (2000). EPA applied
confidence bounds to these predictive
equations to ensure that PWSs operating
at a given CT value are likely to achieve
at least the corresponding log
inactivation level in the CT table.
In identifying confidence bounds for
CT values, EPA was primarily
concerned with uncertainty in the
estimations by Clark et al. (2002a,b) of
the linear relationship between log
inactivation and CT (i.e., uncertainty in
the regression) and with real variability
in the inactivation rate. Such real
variability could be associated with
different populations of oocysts and
different water matrices. In contrast,
variability associated with experimental
error, such as the assays used to
measure loss of infectivity, was a lessor
concern. The purpose of the CT tables
is to ensure a given level of inactivation
and not to predict the measured result
of an individual experiment.
For developing earlier CT values, EPA
has used bounds for confidence in
prediction, which account for both real
variability and experimental error. EPA
believes that this approach was
appropriate due to limited inactivation
data and uncertainty in the sources of
variability in the data. However, the
high doses of ozone and chlorine
dioxide necessary to inactivate
Cryptosporidium create an offsetting
concern with the formation of DBFs
(e.g., bromate and chlorite). In
consideration of this concern, EPA has
employed a less conservative method to
calculate confidence bounds for the
ozone and chlorine dioxide CT values in
today's rule; specifically, EPA has
attempted to exclude experimental error
from the confidence bounds.
In order to estimate confidence
bounds that exclude experimental error,
EPA assessed the relative contribution
of experimental error to the variance
observed in the Cryptosporidium
inactivation data sets. This assessment
was done by comparing variance among
data points with consistent
experimental conditions, which was
attributed to experimental error, with
the total variance in a data set. By this
analysis, EPA estimated that 87.5 and 62
percent of the variance in the
Cryptosporidium inactivation data for
ozone and chlorine dioxide,
respectively, could be ascribed to
experimental error (Sivaganesan 2003,
Messner 2003). EPA then applied these
estimates to the predictive equations
developed by Clark et al. (2002a,b)
using a modified form of a formula for
calculating a 90 percent confidence
bound (Messner 2003).
This analysis produced the CT values
shown in tables IV.D-3 and IV.D-4 for
ozone and chlorine dioxide,
respectively. CT values are provided for
inactivation as low as 0.25-log. Such a
low inactivation level may be used by
PWSs applying ozone in combination
with other disinfectants. Available data
do not support the determination of
conditions for inactivation greater than
3-log, so the CT values in today's rule
do not go beyond this level. The
temperature range of CT values in
today's rule goes to 30 C (86 F), which
will accommodate most natural waters.
If the water temperature is higher than
30 C, temperature should be set to 30 C
for the log inactivation calculation.
PWSs may use the equations provided
as footnotes to tables IV.D-3 and IV.D-
4 to interpolate between CT values.
EPA recognizes that inactivation rates
may be sensitive to water quality and
operational conditions at individual
PWSs. To reflect this potential, PWSs
are allowed to perform a site-specific
inactivation study to determine CT
requirements. The State must approve
the protocols or other information used
to derive alternative CT values. EPA has
provided guidance for such studies in
the Toolbox Guidance Manual.
c. Summary of Major Comments
Public comment on the August 11.
2003 LT2ESWTR proposal supported
the inclusion of ozone and chlorine
dioxide in the microbial toolbox for
Cryptosporidium inactivation.
Commenters stated concerns with the
required criteria for achieving
Cryptosporidium treatment credit,
including the conservatism EPA applied
in developing the CT tables, the ability
of PWSs with different types of source
waters to use these disinfectants, and
the range of conditions covered by the
CT tables. Commenters also made
recommendations for guidance. These
comments and EPA's responses are
summarized as follows.
Some Commenters supported the
proposed CT tables, but others stated
that the statistical approach used to
calculate the confidence bounds from
which the CT values are derived is
overly conservative. These commenters
were concerned that this approach will
increase capital and operating costs and
lead to higher byproduct levels.
In response, EPA believes that the
confidence bounds used for the ozone
and chlorine dioxide CT tables in
today's rule are appropriate and
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709
necessary to ensure that PWSs achieve
intended levels of Cryptosporidium
inactivation. They account only for
uncertainty in the regression of
inactivation data and for variability in
inactivation data that cannot be
attributed to experimental error. This
approach is significantly less
conservative than the approaches used
in CT tables for earlier rules. EPA
employed this less conservative
approach in recognition of the high
disinfectant doses necessary for
Cryptosporidium inactivation and
concern with byproducts.
Commenters were concerned that due
to the relatively high ozone and chlorine
dioxide doses necessary for
Cryptosporidium inactivation, some
PWSs will be unable to use these
disinfectants to achieve required levels
of Cryptosporidium treatment. In
particular, using ozone for high
Cryptosporidium inactivation levels
will be difficult in areas where cold
water temperatures would necessitate
especially high doses or where high
source water bromide levels would
cause problems with bromate formation.
The use of chlorine dioxide for
Cryptosporidium inactivation may be
difficult due to chlorite formation.
EPA recognizes that the use of ozone
and chlorine dioxide to achieve
Cryptosporidium inactivation will
depend on source water factors and will
not be feasible for all PWSs. Due to the
availability of UV, which EPA has
determined to be a feasible technology
for Cryptosporidium inactivation by all
PWS sizes, the feasibility of today's rule
does not depend on the widespread use
of ozone or chlorine dioxide for
compliance. In assessing the impact of
today's rule on PWSs, EPA used ICR
survey data to estimate the fraction of
PWSs that could use ozone or chlorine
dioxide to achieve different levels of
Cryptosporidium inactivation without
exceeding DBP MCLs (see Economic
Analysis for the LT2ESWTR). While
EPA expects that some PWSs will use
these disinfectants, the microbial
toolbox provides many other options for
PWSs to comply with the
Cryptosporidium treatment
requirements of today's rule.
Commenters recommended that EPA
expand the range of conditions
encompassed in the CT tables.
Specifically, commenters asked that CT
tables include values for water
temperatures above 25 C and supported
this request by providing data showing
temperature profiles for water sources
with maximum temperatures near 30 C.
Commenters also requested CT values
for Cryptosporidium inactivation levels
below 0.5-log for PWSs that will use
multiple disinfectants to meet the
treatment requirements in today's rule.
In addition, commenters suggested that
EPA provide equations that PWSs can
use to interpolate between the listed CT
values.
EPA has addressed these
recommendations in today's final rule.
The CT tables for ozone and chlorine
dioxide include values for a water
temperature of 30 C and for 0.25-log
inactivation. Footnotes to these tables
contain equations that PWSs can use to
calculate log inactivation credit for
conditions between those provided in
the tables. PWSs may use these
equations in their process control
systems.
Commenters made recommendations
for guidance on the use of ozone and
chlorine dioxide to comply with today's
rule. These recommendations concern
topics like monitoring disinfection
reactors, procedures for calculating
disinfectant concentration and contact
time, site specific studies, and
synergistic effects of multiple
disinfectants. EPA has addressed these
topics in the Toolbox Guidance Manual.
15. Ultraviolet Light
a. Today's Rule
PWSs may use ultraviolet (UV) light
to comply with Cryptosporidium
treatment requirements in today's rule.
as well as Giardia lamblia and virus
treatment requirements in existing
regulations. To receive treatment credit,
PWSs must operate UV reactors
validated to achieve the required UV
dose, as shown in the table in this
section, and monitor their UV reactors
to demonstrate operation within
validated conditions. Specific criteria
are as follows:
Required UV Doses
• UV dose (fluence) is the product of
the UV intensity over a surface area
(fluence rate) and the exposure time.
PWSs must use validation testing to
demonstrate that a UV reactor achieves
the UV doses shown in Table IV.D-5 in
order to receive the associated
inactivation credit.
TABLE IV.D-5.—UV DOSE REQUIREMENTS FOR CRYPTOSPORIDIUM, GIARDIA LAMBLIA, AND VIRUS INACTIVATION CREDIT
Log credit
0 5 .
1 0
1 5 .
2 0
2 5
30
3 5
4.0
Cryptosporidium UV
dose (mJ/cm2)
1 6
2.5
39
58
8.5
12
15
22
Giardia lamblia UV
dose (mJ/cm2)
1 5
2.1
30
52
7.7
11
15
22
Virus UV dose (mJ/
cm2)
39
58
79
100
121
143
163
186
• The dose values in Table IV.D-5 are
for UV light at a wavelength of 254 nm
as delivered by a low pressure mercury
vapor lamp. However, PWSs may use
this table to determine treatment credits
for other lamp types through validation
testing, as described in the UV
Disinfection Guidance Manual. The
dose values in Table IV.D-5 apply to
post-filter applications of UV in
filtration plants and to PWSs that meet
all applicable filtration avoidance
criteria.
UV Reactor Validation Testing
• The validation test may be reactor-
specific or site-specific. Unless the State
approves an alternative approach, this
testing must involve the following: (1)
Full scale testing of a reactor that
conforms uniformly to the UV reactors
used by the PWS, and (2) inactivation of
a test microorganism whose dose
response characteristics have been
quantified with a low pressure mercury
vapor lamp.
• Validation testing must identify
ranges for parameters the PWS can
monitor to ensure that the required UV
dose is delivered during operation.
These parameters must include flow
rate, UV intensity as measured by UV
sensors, and UV lamp status.
• The operating parameters
determined by validation testing must
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account for the following factors: (1) UV
absorbance of the water, (2) lamp
fouling and aging, (3) measurement
uncertainty of UV sensors, (4) dose
distributions arising from the flow
velocity profiles through the reactor, (5)
failure of UV lamps or other critical
system components, and (6) inlet and
outlet piping or channel configurations
of the UV reactor. In the UV
Disinfection Guidance Manual, EPA
describes recommended approaches for
reactor validation that address these
factors.
UV Reactor Monitoring
• PWSs must monitor for the
parameters necessary to demonstrate
operation within the validated
conditions of the required UV dose.
These parameters must include flow
rate, UV intensity as measured by UV
sensors, and UV lamp status. PWSs
must check the calibration of UV
sensors and recalibrate in accordance
with a protocol approved by the State.
• For PWSs using UV light to meet
microbial treatment requirements, at
least 95 percent of the water delivered
to the public every month must be
treated by UV reactors operating within
validated conditions for the required UV
dose.
b. Background and Analysis
Numerous studies have demonstrated
that UV light is effective for inactivating
Cryptosporidium, Giardia lamblia, and
other microbial pathogens at relatively
low doses (Clancy et al. 1998, 2000,
2002, Bukhari et al. 1999, Craik et al.
2000, 2001, Landis et al. 2000, Sommer
et al. 2001, Shin et al. 2001, and
Oppenheimer et al. 2002). EPA has
determined that UV light is a feasible
technology for PWSs of all sizes to
inactivate Cryptosporidium.
Accordingly, EPA expects that UV is
one of the primary technologies PWSs
will use to comply with
Cryptosporidium treatment
requirements in today's rule.
The Stage 2 M-DBP Advisory
Committee recommended that EPA
establish standards for the use of UV to
comply with drinking water treatment
requirements. These standards include
the UV doses necessary for different
levels of Cryptosporidium, Giardia
lamblia, and virus inactivation and a
protocol for validating the disinfection
performance of UV reactors. The
Committee also directed EPA to develop
a UV disinfection guidance manual to
familiarize States and PWSs with
important design and operational issues
for UV installations.
The August 11, 2003 LT2ESWTR
proposal included UV doses for PWSs to
achieve treatment credit of up to 3-log
for Cryptosporidium and Giardia
lamblia and up to 4-log for viruses,
along with associated reactor validation
and monitoring requirements. The
proposal also required unfiltered PWSs
using UV to achieve the UV dose for the
required level of Cryptosporidium
inactivation in at least 95 percent of the
water delivered to the public even'
month (USEPA 2003a).
Today's final rule establishes these
criteria with no changes from the
proposed rule. However, EPA has
expanded the UV dose table to include
4-log inactivation of Cryptosporidium
and Giardia lamblia and has expanded
the 95 percent compliance requirement
to include filtered PWSs and to cover
Giardia lamblia and virus inactivation.
The following discussion summarizes
the basis for these criteria.
The UV dose values in Table IV.D-5
are based on meta-analyses of UV
inactivation studies with
Cryptosporidium parvum, Giardia
lamblia, Giardia muris, and adenovirus
(Qian et al. 2004, USEPA 2003a). EPA
has expanded the dose values for
Cryptosporidium and Giardia lamblia
from 3- to 4-log inactivation because
available data support criteria for this
level of treatment. Neither today's rule
nor any existing regulations require
PWSs to provide Cryptosporidium
inactivation above this level, so EPA has
not expanded the UV dose tables
further. While today's rule requires up
to 5.5-log Cryptosporidium treatment by
filtered PWSs, at least 2.0-log of this
treatment must be achieved by physical
removal.
The required UV doses for
inactivation of viruses are based on the
dose-response of adenovirus because
among waterborne pathogenic viruses
that have been studied, it appears to be
the most UV resistant. As summarized
in Embrey (1999), adenoviruses have
been identified as the second most
important agent of gastroenteritis in
children and can cause significant
adverse health effects, including death,
in persons with compromised immune
systems. They are associated with fecal
contamination in water and have been
implicated in waterborne disease
outbreaks.
EPA used data from studies
performed with low pressure mercury
vapor lamps on water with turbidity
representative of filtered water to derive
the UV dose values in Table IV.D-5.
Studies with low pressure mercury
vapor lamps were selected because they
allow the UV dose to be accurately
quantified (see USEPA 2003a for
specific studies). The UV dose values in
Table IV.D-5 can be applied to medium
pressure mercury vapor lamps and other
lamp types through UV reactor
validation testing, as described in the
UV Disinfection Guidance Manual. Due
to the potential for particulate matter to
interfere with UV disinfection, the
application of these dose values is
limited to post-filtration in filtered
PWSs and to unfiltered PWSs.
Flow-through UV reactors deliver a
distribution of doses due to variations in
light intensity and particle flow path
through the reactor. To best account for
the dose distribution, the validation test
must use a challenge microorganism to
determine the degree of inactivation
achieved by the UV reactor. This level
of performance must then be associated
to the UV dose requirements in Table
IV.D-5 through known dose-response
relationships for the challenge
microorganism and target pathogen in
order to assign disinfection credit to the
UV reactor. States may approve an
alternative basis for awarding UV
disinfection credit.
Today's rule requires full-scale testing
of UV reactors to validate the operating
conditions under which the reactors can
deliver a required UV dose. EPA
believes this testing is necessary due to
the uncertainty associated with
predicting reactor disinfection
performance entirely through modeling
or through reduced-scale testing. Under
today's rule. EPA intends UV reactor
validation testing to be reactor-specific
and not site-specific. This means that
once a UV reactor has been validated for
a range of operating conditions, the
validation test results can be applied by
all PWSs that will operate within those
conditions without the need for
retesting at each individual site.
Validation testing must account for
factors that will influence the dose
delivered by UV reactors during routine
operation. These factors include UV
absorbance, lamp fouling, lamp aging.
the performance of UV intensity
sensors, hydraulic flow path and
residence time distributions. UV lamp
failure, and reactor inlet and outlet
hydraulics. The successful outcome of
validation testing is the determination
of acceptable operating ranges for
parameters the PWSs can monitor to
ensure delivery of the required UV dose
during treatment. The specific
parameters will vary depending on the
reactor control strategy. In all cases,
however, PWSs must monitor UV
intensity within the reactor as measured
by UV sensors, the flow rate, and the
status of lamps. EPA believes that any
effective UV reactor control strategy will
involve monitoring for these parameters.
Today's rule requires all PWSs using
UV for disinfection compliance to treat
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711
at least 95 percent of the water
distributed to the public each month
with UV reactors operating within
validated conditions for the required UV
dose. EPA views this 95 percent limit as
a feasible minimum level of
performance for PWSs to achieve, while
ensuring the desired level of health
protection is provided. For purposes of
design and operation, PWSs should
strive to deliver the required UV dose at
all times during treatment.
EPA developed these requirements
and the associated UV Disinfection
Guidance Manual solely for public
water systems using UV light to meet
drinking water disinfection standards
established under SDWA. EPA has not
addressed and did not consider the
extension of these requirements and
guidance to other applications,
including point of entry or point of use
devices for residential water treatment
that are not operated by public water
systems to meet SDWA disinfection
standards.
c. Summary of Major Comments
Public comment on the August 11,
2003 LT2ESWTR proposal supported
the inclusion of UV light in the
microbial toolbox for Cryptosporidium
inactivation. EPA received significant
comment on the UV dose tables, the use
of adenovirus as the basis for virus UV
dose requirements, UV compliance
standards for filtered systems, and
safety factors associated with draft
guidance. These comments and EPA's
responses are summarized as follows.
Commenters generally supported the
proposed UV dose values for
Cryptosporidium and Giardia lamblia
inactivation and recommended that EPA
incorporate these values into the final
rule. Several commenters requested that
EPA provide values for 3.5-, 4.0- or
higher log inactivation of
Cryptosporidium and Giardia lamblia
because available dose-response data
include this range. Due to factors like
tailing and censoring in the underlying
dose-response data, some commenters
stated that the proposed UV dose values
are conservative and advised EPA to
consider this conservatism when
recommending additional safety factors
in guidance.
In response, EPA has extended the UV
dose table in today's rule to cover 3.5-
and 4.0-log Cryptosporidium and
Giardia lamblia inactivation. None of
EPA's regulations require inactivation of
Cryptosporidium or Giardia lamblia
above these levels, so EPA has not
established UV dose requirements for
inactivation above 4-log. EPA believes
that the statistical analysis used to
determine the required UV doses
appropriately accounts for variability,
tailing, and censoring in the underlying
dose-response data. However, the
required UV dose values do not account
for bias and uncertainty associated with
UV reactor validation and monitoring,
which are addressed in guidance.
Several commenters were concerned
with the use of adenovirus to set UV
dose requirements for virus inactivation
because the resulting dose values are
several times higher than typical UV
doses for drinking water disinfection.
These high dose values impact the
feasibility of PWSs using UV to fully
meet virus treatment requirements,
which will hinder the use of UV to
reduce DBPs and for point-of-entry
treatment. Commenters requested that
EPA consider waterborne viruses that
are more UV-sensitive, such as rotavirus
or hepatitus, when setting UV dose
requirements. Commenters noted that
adenovirus commonly causes infections
of the lung or eye, which are not
transmitted through water consumption,
and that no drinking water outbreaks
associated with adenovirus have been
reported in the United States.
EPA recognizes that the UV doses for
virus inactivation in today's rule are
relatively high and that this will limit
the degree to which PWSs can use UV
for virus treatment. Based on occurrence
and health effects, however, EPA
continues to believe that UV dose
requirements should be protective for
adenovirus. The existing requirement
for 4-log virus treatment, as established
under the SWTR, applies to all
waterborne viruses of public health
concern in PWSs. Adenovirus is
consistently found in water subject to
fecal contamination and can be
transmitted through consumption of or
exposure to contaminated water. It is a
common cause of diarrheal illness,
particularly in children, and fecal
shedding is prevalent in asymptomatic
adults. While illness from adenovirus is
typically self-limiting, severe health
effects, including death, can occur.
Consequently, EPA regards adenovirus
as a potential health concern in PWSs
and has established UV dose
requirements to address it.
Many commenters recommended that
EPA establish a compliance standard for
the operation of UV reactors within
validated conditions by filtered PWSs,
similar to the 95 percent standard
proposed for unfiltered PWSs.
Commenters were concerned that
without a clear compliance standard in
the rule, filtered PWSs would be held to
inconsistent and unclear standards,
which would impede the design and
implementation of UV systems. Some
commenters recommended that filtered
PWSs by held to the same 95 percent
standard as unfiltered PWSs, while
others recommended a lower 90 percent
standard on the basis that filtered PWSs
have more barriers of protection.
EPA agrees that establishing a clear
compliance standard for the use of UV
to meet inactivation requirements is
appropriate. For filtered PWSs using UV
to meet microbial treatment
requirements, today's final rule requires
at least 95 percent of the water
distributed to consumers to be treated
by UV reactors operating within
validated conditions. This is the same
standard that applies to unfiltered
PWSs. EPA believes that a 95th
percentile standard is feasible for all
PWSs and represents the minimum
level of performance that should be
achieved. During routine operation,
PWSs should endeavor to maintain UV
reactors within validated conditions for
the required UV dose at all times.
E. Disinfection Benchmarking for
Giardia lamblia and Viruses
1. Today's Rule
The purpose of disinfection
benchmarking under today's rule is to
ensure that PWSs maintain protection
against microbial pathogens as they
implement the Stage 2 DBPR and
LT2ESWTR. If a PWS proposes to make
a significant change in disinfection
practice, the PWS must perform the
following:
• Develop a disinfection profile for
Giardia lamblia and viruses. A
disinfection profile consists of
documenting Giardia lamblia and virus
log inactivation levels at least weekly
over a period of at least one year. PWSs
that operate for less than one year must
profile only during the period of
operation. The calculated log
inactivation levels must include the
entire treatment plant and must be
based on operational and water quality
data, such as disinfectant residual
concentration(s), contact time(s),
temperatur3(s), and, where necessary,
pH. PWSs ijnay create profiles by
conducting] new weekly (or more
frequent) monitoring and/or by using
previously collected data. A PWS that
created a Giardia lamblia disinfection
profile und|er the IESWTR or
LTlESWTR may use the operational
data collected for the Giardia lamblia
profile to create a virus disinfection
profile.
• Calculate a disinfection benchmark,
using the following procedure: (1)
Determine the calendar month with the
lowest log inactivation; (2) The lowest
month becomes the critical period for
that year; (3) If acceptable data from
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multiple years are available, the average
of critical periods for each year becomes
the benchmark; (4) If only one year of
data is available, the critical period for
that year is the benchmark.
• Notify the State before
implementing the significant change in
disinfection practice. The notification to
the State must include a description of
the proposed change, the disinfection
profiles and inactivation benchmarks for
Giardia lamblia and viruses, and an
analysis of how the proposed change
will affect the current inactivation
benchmarks.
For the purpose of these
requirements, significant changes in
disinfection practice are defined as (1)
moving the point of disinfection (this is
not intended to include routine seasonal
changes already approved by the State),
(2) changing the type of disinfectant, (3)
changing the disinfection process, or (4)
making other modifications designated
as significant by the State. The
Disinfection Profiling and
Benchmarking Guidance Manual
provides information to PWSs and
States on the development of
disinfection profiles, identification and
evaluation of significant changes in
disinfection practices, and
considerations for setting an alternative
benchmark (USEPA 1999d).
2. Background and Analysis
A goal in the development of rules to
control microbial pathogens and
disinfection byproducts (DBFs) is the
balancing risks between these two
classes of contaminants. EPA
established disinfection profiling and
benchmarking under the IESWTR and
LT1ESWTR. based on a
recommendation by the Stage 1 M-DBP
Advisory Committee, to ensure that
PWSs maintained adequate protection
against pathogens as they reduced risk
from DBFs. EPA is extending profiling
and benchmarking requirements to the
LT2ESWTR for the same objective.
Some PWSs will make significant
changes in their current disinfection
practice to meet TTHM and HAAS
requirements under the Stage 2 DBPR
and to provide additional treatment for
Cryptosporidium under the LT2ESWTR.
To ensure that these PWSs maintain
disinfection that is effective against a
broad spectrum of microbial pathogens,
EPA believes that PWSs and States
should evaluate the effects of significant
changes in disinfection practice on
current microbial treatment levels.
Disinfection profiling and
benchmarking serves as a tool for
making such evaluations.
The August 11, 2003 LT2ESWTR
proposal included disinfection profiling
and benchmarking requirements. Under
the proposal, profiling for Giardia
lamblia and viruses was required if a
PWS was required to monitor for
Cryptosporidium or, in the case of small
PWSs, exceeded 80 percent of the
TTHM or HAAS MCL based on a
locational running annual average.
Under this approach, most large PWSs
and a significant fraction of small PWSs
were required to develop profiles. The
proposal also included a schedule for
disinfection profile development. Those
PWSs that developed profiles were then
required to calculate a disinfection
benchmark and notify the State if they
proposed to make a significant change
in disinfection practice.
In today's final rule, EPA has
significantly modified the applicability
requirements for disinfection profiling.
PWSs are only required to develop a
disinfection profile if they propose to
make a significant change in
disinfection practice after completing
the first round of source water
monitoring. EPA has made this change
from the proposal because under the
LT2ESWTR and Stage 2 DBPR, most
PWSs will not be required to make
significant changes to their disinfection
practice. Consequently, most PWSs will
not need a disinfection profile. EPA
believes that disinfection profiling
requirements should be targeted to those
PWSs that will make significant
disinfection changes.
EPA has also eliminated the
scheduling requirements for
development of the disinfection profile
in order to provide more flexibility to
PWSs and States. Today's rule only
requires that PWSs notify States prior to
making a significant change in their
disinfection practice and that this
notification include the disinfection
profiles and benchmarks, along with an
analysis of how the proposed change
will affect the current benchmarks. EPA
believes that PWSs should collect the
operational data needed to develop
disinfection profiles, such as
disinfectant residual, water temperature,
and flow rate, as part of routine practice.
PWSs that do not have current
disinfection profiles should record this
operational information at least weekly
for one year so that they can use it to
develop disinfection profiles if required.
Today's rule retains the proposed
requirement that when disinfection
profiling is required, PWSs must
develop profiles for both Giardia
lamblia and viruses. EPA believes that
profiling for both target pathogens is
appropriate because the types of
treatment changes that PWSs will make
to comply with the Stage 2 DBPR or
LT2ESWTR could lead to a significant
change in the inactivation level for one
pathogen but not the other. For
example, a PWS that switches from
chlorine to UV light to meet Giardia
lamblia inactivation requirements is
likely to maintain a high level of
treatment for this pathogen. The level of
treatment for viruses, however, may be
significantly reduced. In general, viruses
are much more sensitive to chlorine
than Giardia but are more resistant to
UV. The situation for a PWS switching
to microfiltration is similar. The same
operational data are used to develop
disinfection profiles for both Giardia
lamblia and viruses.
As was the case with the IESWTR and
LTlESWTR, the disinfection benchmark
under today's rule is not intended to
function as a regulatory standard.
Rather, the objective of these provisions
is to facilitate interactions between the
States and PWSs to assess the impact on
microbial risk of proposed changes to
disinfection practice. Final decisions
regarding levels of disinfection for
Giardia lamblia and viruses beyond the
minimum required by regulation will
continue to be left to the States and
PWSs. To ensure that the level of
treatment for both protozoan and viral
pathogens is appropriate, States and
PWSs should consider site-specific
factors such as source water
contamination levels and the reliability
of treatment processes.
3. Summary of Major Comments
EPA received significant public
comment on disinfection profiling and
benchmarking requirements in the
August 11, 2003 proposal. A few
commenters supported the proposed
requirements but most raised concerns
with the burden and usefulness of
disinfection profiling and requested
greater flexibility. These comments and
EPA's responses are summarized as
follows.
Commenters stated that disinfection
profiling diverts PWS and State
resources from other public health
protection activities and presents an
incomplete picture of the information
that should be considered when
evaluating disinfection changes.
Further, some States can only require
the level of treatment specified in
regulations (e.g., the SWTR, IESWTR,
LTlESWTR) and cannot use a
disinfection benchmark to enforce a
higher treatment standard. Some
commenters also disagreed with
requiring a disinfection profile for
viruses, since current disinfection
practices targeting Giardia lamblia
typically achieve much greater virus
inactivation than required.
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713
To address these concerns,
commenters requested that profiling
only be required for PWSs prior to
switching disinfectants or that States be
allowed to grant waivers from
disinfection profiling requirements.
Commenters also recommended that
States be given flexibility to determine
the appropriate time for PWSs to
develop disinfection profiles, if
necessary. In regard to virus profiling,
some commenters suggested that it only
be required for PWSs that have not
developed profiles for Giardia lamblia
or that are switching disinfectants to
UV.
In response, EPA has modified the
proposed requirements for disinfection
profiling and benchmarking from the
proposal to significantly reduce the
burden on PWSs and States. In today's
final rule, profiling is only required for
PWSs that propose to make a significant
change in disinfection practice. EPA
projects that most PWSs will not be
required to make treatment changes to
comply with the LT2ESWTR and Stage
2 DBPR and, as a result, will not be
required to develop disinfection
profiles. Further, today's rule gives
PWSs and States flexibility to determine
the timing for developing disinfection
profiles and only requires that the
profiles and benchmarks be included in
a notification to the State before a PWS
implements a significant change in
disinfection practice. For PWSs that
have not developed disinfection
profiles, EPA recommends recording the
necessary operational data at least
weekly over one year so that a profile
can be prepared if needed.
For PWSs that propose to make a
significant change in disinfection
practice, today's rule maintains the
proposed requirement for a disinfection
profile for viruses. EPA recognizes that
current disinfection practices with
chlorine typically achieve far more virus
inactivation than required. However, the
types of treatment changes that PWSs
will make to comply with the Stage 2
DBPR or LT2ESWTR, such as
implementing UV or micro filtration, are
likely to maintain high levels of
treatment for Giardia lamblia but may
result in a significant decrease in
treatment for viruses. Consequently,
EPA believes that States and PWSs
should consider whether such a
decrease in virus treatment will occur
when evaluating proposed treatment
changes.
Moreover, developing a virus
disinfection profile does not require the
collection of operational data beyond
that necessary to develop a Giardia
lamblia disinfection profile. Therefore,
today's rule allows PWSs to use
previously developed Giardia lamblia
disinfection profiles and allows the
operational data that underlie the
Giardia lamblia profile to be used for a
virus disinfection profile.
F. Requirements for Systems With
Uncovered Finished Water Storage
Facilities
I. Today's Rule
Today's rule requires PWSs that store
treated water in an open reservoir (i.e.,
use uncovered finished water storage
facilities) to do either of the following:
• Cover the finished water storage
facility; or
• Treat the discharge of the
uncovered finished water storage
facility that is distributed to consumers
to achieve inactivation and/or removal
of 4-log virus, 3-log Giardia lamblia, and
2-log Cryptosporidium.
PWSs must notify the State if they use
uncovered finished water storage
facilities no later than April 1, 2008.
PWSs must either meet the
requirements of today's rule for covering
or treating each facility or be in
compliance with a State-approved
schedule for meeting these requirements
no later than April 1, 2009.
Today's rule revises the definition of
an uncovered finished water storage
facility as follows: uncovered finished
water storage facility is a tank, reservoir,
or other facility used to store water that
will undergo no further treatment to
reduce microbial pathogens except
residual disinfection and is directly
open to the atmosphere.
2. Background and Analysis
The requirements in today's rule for
PWSs that use uncovered finished water
storage facilities (open reservoirs) are
based on an assessment of the types and
sources of contaminants in open
reservoirs, the efficacy and feasibility of
regulatory approaches to reduce risks
from this contamination, and comments
on the August 11, 2003 proposal. The
following discussion summarizes this
assessment.
a. Types and sources of contaminants
in open reservoirs. The storage of treated
drinking water in open reservoirs can
lead to significant water quality
degradation and health risks to
consumers (USEPA 1999e). Examples of
such water quality degradation include
increases in algal cells, coliform
bacteria, heterotrophic plate count
bacteria, turbidity, particulates, DBFs,
metals, taste and odor, insect larvae,
Giardia, Cryptosporidium, and nitrate
(USEPA 1999e). Contamination of open
reservoirs occurs through surface water
runoff, bird and animal wastes, human
activity, algal growth, insects and fish,
and airborne deposition. Additional
information on these sources of
contamination follows.
If a reservoir receives surface water
runoff, the SWTR requires that it be
treated as raw water storage, rather than
a finished water reservoir (40 CFR
141.70(a)). Nevertheless, many
uncovered finished water reservoirs
have been found to be affected by
surface water runoff, which may include
agricultural fertilizers, pesticides,
microbial pathogens, automotive fluids
and residues, sediment, nutrients,
natural organic matter, and metals
(USEPA 1999e, LeChevallier et al.
1997).
Birds are a significant cause of
contamination in open reservoirs, and
bird feces may contain coliform
bacteria, viruses, and other human
pathogens, including vibrio cholera,
Salmonella, Mycobacteria, Typhoid,
Giardia, and Cryptosporidium
(Geldreich and Shaw 1993). Birds can
ingest pathogens at landfills or
wastewater treatment plants prior to
visiting a reservoir and have been
shown to carry and pass infectious
Cryptosporidium parvum (Graczyk et al.
1996). Five to twenty percent of birds
are estimated to be periodically infected
with human pathogens like Salmonella
(USEPA 1999e). A 1993 Salmonella
outbreak in Gideon, MO that resulted in
seven deaths was traced to pigeons
roosting in a finished water storage tank.
Animals that are either known or
suspected to contaminate open
reservoirs include dogs, cats, deer, rats,
mice, opossums, squirrels, muskrats,
raccoons, beavers, rabbits, and frogs.
Some animals are infected with human
pathogens like Cryptosporidium, which
can be discharged to the reservoirs in
feces or transmitted by direct contact
between animals and the water (Payer
and Unger 1986, Current 1986, USEPA
1999e).
Open reservoirs are exposed to
contamination through human
activities. Pesticides and fertilizers can
enter open reservoirs through runoff and
airborne drifts from spray applications.
Swimming in reservoirs can result in
pathogens being passed from the feces,
shedded skin, and mucus membranes of
infected persons. PWSs routinely find a
great variety of items that have been
thrown into open reservoirs, despite the
use of high fences and set-back
distances. Such items include baby
carriages, beer bottles, bicycles, bullets,
dead animals, dog waste bags, fireworks,
garbage cans, a pay phone, shoes, and
shovels (USEPA 1999e). These items are
a potential source of pathogens and
toxic substances and clearly indicate the
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susceptibility of open reservoirs to
intentional contamination.
Algal growth is common in open
reservoirs and can lead to aesthetic
problems like color, taste, and odor, and
may generate cyanobacterial toxins,
which cause headaches, fever, diarrhea,
abdominal pain, nausea, and vomiting.
In addition, algae can increase other
contaminants like DBFs by increasing
biomass within reservoirs, and
corrosion products like lead, through
causing significant pH fluctuations.
Algae have been shown to shield
bacteria from the effects of disinfection
(Geldreich and Shaw 1993).
Open reservoirs may be infested with
the larvae of insects such as midge flies,
water fleas, and gnats, which can be
carried through the distribution system
from the reservoir (USEPA 1999e).
Chlorination is ineffective against midge
fly larvae. Fly outbreaks may increase
the presence of insect-eating birds,
which present another source of
contamination as described earlier.
Some open finished water reservoirs
have been found to support fish
populations.
Open reservoirs also are subject to
airborne deposition of contaminants,
such as industrial pollutants,
automobile emissions, pollen, dust,
particulate matter, and bacteria.
Deposition occurs during all types of
weather conditions, but is likely to be
accelerated during precipitation events
as air pollutants are transported from
the air column above the reservoir by
' rain or snow.
b. Regulatory approaches to reduce
risk from contamination in open
reservoirs. For many decades, public
health agencies and professional
associations like the American Public
Health Association, the U.S. Public
Health Service, and the American Water
Works Association have recommended
that all finished water reservoirs be
covered (USEPA 1999e). In the IESWTR
and LTlESWTR, EPA prohibited the
construction of new uncovered finished
water reservoirs (40 CFR 141.170(c) and
141.511). These regulations did not
address existing uncovered finished
water reservoirs, however. In the
preamble to the IESWTR. EPA stated
that a requirement to cover existing
reservoirs would be considered when
data to develop national cost estimates
were available.
EPA has now collected the necessary
data to estimate costs associated with
regulatory control strategies for
uncovered finished water reservoirs.
The August 11, 2003 LT2ESWTR
proposal included three options for
PWSs with uncovered finished water
reservoirs to reduce risk: (1) cover the
reservoir, (2) treat the discharge to
achieve 4-log virus inactivation, or (3)
implement a State-approved risk
mitigation plan (USEPA 2003a). These
options reflected recommendations from
the Stage 2 M-DBP Advisory Committee
(USEPA 2000a). Today's final rule
includes the first option to cover,
modifies the second option to also
require 3-log Giardia and 2-log
Cryptosporidium treatment, and does
not establish an option for a risk
mitigation plan. The following
discussion describes the basis for these
changes.
As described earlier, studies have
shown that small mammals and birds
that live near water may be infected
with Cryptosporidium and Giardia and
may shed infectious oocysts and cysts
into the water (Graczyk et al. 1996,
Payer and Unger 1986, Current 1986).
LeChevallier et al. (1997) evaluated
Cryptosporidium and Giardia levels in
six uncovered finished water reservoirs.
The geometric mean concentration of
Cryptosporidium was 1.2 oocysts/100 L
in the inlet samples and 8.1 oocysts/100
L in the effluent samples (i.e., 600
percent increase in the reservoir). For
Giardia, the geometric mean
concentrations in the inlet and effluent
samples were 1.9 and 6.1 cysts/100 L,
respectively (i.e., 200 percent increase
in reservoir).
Most, if not all. PWSs would treat to
achieve 4-log virus inactivation with
chlorine. Based on EPA guidance, the
dose of chlorine necessary for 4-log
virus inactivation would not achieve
even 0.5-log Giardia inactivation and
would produce no inactivation of
Cryptosporidium (USEPA 1991b).
Consequently, PWSs treating for viruses
in open reservoirs, as proposed, would
provide very little protection against
contamination by Giardia and
Cryptosporidium.
Due to the demonstrated potential for
contamination by Giardia and
Cryptosporidium in open reservoirs and
the ineffectiveness of virus treatment
against these pathogens, today's rule
requires PWSs to treat for Giardia and
Cryptosporidium in addition to viruses
if they do not cover their finished water
reservoirs. Specifically, today's rule
specifies the same baseline treatment as
required for a raw unfiltered source,
which is 4-log virus, 3-log Giardia, and
2-log Cryptosporidium reduction.
EPA believes that requiring treatment
for viruses, Giardia, and
Cryptosporidium in uncovered finished
water reservoirs is consistent with
SDWA section 1412(b)(7)(A), which
authorizes the use of a treatment
technique to prevent adverse health
effects to the extent feasible if
measuring the contaminant is not
feasible. Monitoring for these pathogens
at the very low levels that would cause
public health concern and at the
frequency necessary to detect
contamination events is not feasible
with available analytical methods. EPA
has determined that with the
availability of technologies like UV,
treating for Giardia, Cryptosporidium,
and viruses is feasible for all PWS sizes.
Today's rule does not allow PWSs to
implement a risk mitigation plan as an
alternative to covering a reservoir or
treating the discharge because EPA does
not believe that a risk mitigation plan
would provide equivalent public health
protection. Consequently, a risk
mitigation plan would not meet the
statutory provision for a treatment
technique to prevent adverse health
effects from pathogens like Giardia and
Cryptosporidium to the extent feasible
(SDWA section 1412(b)(7)(A)).
As discussed earlier, open reservoirs
are subject to contamination from many
sources, including runoff, birds,
animals, humans, algae, insects, and
airborne deposition. Control measures
can provide a degree of protection
against some of these sources (e.g.. bird
deterrent wires, security fences with
setback distances). All PWSs are
significantly constrained, however, in
the degree to which they can implement
such measures with existing open
reservoirs due to factors like the size of
the reservoir, the location of the
reservoir (e.g., within residential
communities or parks), and the existing
infrastructure. For example, many open
finished water reservoirs are impacted
by runoff, despite the fact that this has
been prohibited for many years under
existing regulations (USEPA 1999e).
EPA has concluded that implementing
control measures that would be highly
effective against all sources of
contamination of open reservoirs would
not be feasible for PWSs. Accordingly,
today's rule does not allow this option.
c. Definition of uncovered finished
water storage facility. The IESWTR
established the following definition for
an uncovered finished water storage
facility: uncovered finished water
storage facility is a tank, reservoir, or
other facility used to store water that
will undergo no further treatment
except residual disinfection and is open
to the atmosphere.
In the August 11, 2003, proposed
LT2ESWTR, EPA requested comment on
whether this definition should be
revised. EPA was concerned that it
would not include certain cases in
which water is stored in an open
reservoir after a PWS completes
treatment to reduce microbial
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715
pathogens. Such a case would be a PWS
that applies a corrosion inhibitor to the
effluent of an open reservoir where
water is stored after filtration and
primary disinfection. In this case, the
PWS could claim that the corrosion
inhibitor constitutes additional
treatment and, consequently, the open
reservoir does not meet EPA's definition
of an uncovered finished water storage
facility. However, the water stored in
the open reservoir would be subject to
microbial contamination from the
sources described in this section and
would undergo no further treatment for
this contamination.
Today's rule revises the definition of
an uncovered finished water storage
facility in two ways: (1) The phrase "to
reduce microbial pathogens" is inserted
following the word "treatment;" and (2)
the word "directly" is inserted prior to
"open to the atmosphere." The first
change ensures that an open reservoir
where water is stored after a PWS has
completed filtration (where required)
and primary disinfection will be
appropriately classified as an uncovered
finished water storage facility. Whether
a PWS applies corrosion control or other
treatment to maintain water quality in
the distribution system will not affect
this determination.
The second change clarifies that
covered reservoirs with air vents or
overflow lines are not uncovered
finished water storage facilities. Such
air vents and overflow lines are open to
the atmosphere but are usually hooded
or screened to prevent contamination of
the water. Consequently, these
reservoirs are not directly open to the
atmosphere and are not subject to the
requirements of today's rule for
uncovered finished water storage
facilities.
3. Summary of Major Comments
EPA received significant public
comment on requirements for
uncovered finished water storage
facilities in the August 11, 2003
proposal. Major issues raised by
commenters include whether to require
all reservoirs to be covered, requiring
treatment for Giardia and
Cryptosporidium, support for the
proposed options, and revising the
definition of an uncovered finished
water storage facilities. A summary of
these comments and EPA's responses
follows.
Several commenters recommended
that EPA require all finished water
reservoirs to be covered. These
commenters stated that making an
uncovered reservoir equal in quality to
a covered reservoir is not possible—
open reservoirs will always be
contaminated by fecal material from
birds and small mammals, as well as
increased DBFs due to algae and other
aquatic organisms, airborne
contaminants, and sediment stirred up
by wind. Commenters were also
concerned that uncovered reservoirs are
a major vulnerability for PWS security
(i.e., intentional contamination). Some
commenters cited the fact that there are
hundreds of thousands of covered
finished water reservoirs in comparison
to approximately 100 uncovered
finished water reservoirs as evidence
that the public health risks of open
reservoirs are widely recognized.
EPA agrees that storing treated water
in open reservoirs presents a risk to
public health. With today's final rule,
EPA expects that many PWSs will cover
or eliminate uncovered finished water
reservoirs. For reservoirs where
covering is not feasible, EPA believes
that treating the water for Giardia,
Cryptosporidium, and viruses will
provide protection against the range of
pathogens likely to contaminate the
reservoir.
Many commenters supported
requiring treatment for Giardia and
Cryptosporidium for PWSs that treat the
reservoir discharge. Commenters stated
that reservoirs should either be covered
or treated as unfiltered sources
(meaning 3-log Giardia, 2-log
Cryptosporidium, and 4-log virus
treatment). The LeChevallier et al.
(1997) study was cited as demonstrating
increases in Giardia and
Cryptosporidium in uncovered finished
water reservoirs, and commenters noted
that treatment for viruses would not be
effective against these protozoa. EPA
agrees with these comments and today's
rule requires treatment for Giardia and
Cryptosporidium, as well as viruses, by
PWSs that do not cover their reservoirs.
Some commenters expressed support
for the proposed options, including
allowing risk mitigation plans as an
adequate remedy for an uncovered
reservoir. These commenters
characterized the proposal as providing
reasonable alternatives to the substantial
costs involved in covering reservoirs or
providing alternative storage.
Commenters stated that strategies
included in a risk management plan
could address the range of
microorganisms for which treatment is
necessary, depending on site-specific
circumstances.
EPA recognizes that covering or
finding alternative storage for uncovered
finished water reservoirs can be costly.
While EPA believes that covering
finished water reservoirs is the most
effective approach to protecting public
health, today's rule allows PWSs to
provide treatment for Giardia,
Cryptosporidium, and viruses as a
feasible alternative. As described earlier,
EPA does not believe that providing
treatment only for viruses, as proposed,
would be protective against the range of
pathogens that contaminate open
reservoirs. Further, EPA has concluded
that implementing a risk mitigation plan
that would provide equivalent
protection to covering or treating a
reservoir is not feasible. This is due to
the many potential sources of
contamination and the significant
limitations that all PWSs have in the
control measures they can implement
for existing open reservoirs.
Commenters supported revising the
definition of uncovered finished water
storage facilities to include situations
where PWSs apply a treatment like
corrosion control to water stored in an
open reservoir after the water has
undergone filtration, where required,
and primary disinfection. In addition,
commenters recommended that EPA
clarify that "open to the atmosphere" in
the definition does not include vents
and overflow lines in covered
reservoirs. EPA agrees with these
comments and today's rule is consistent
with them.
G. Compliance Schedules
1. Today's Rule
This section specifies compliance
dates for the monitoring and treatment
technique requirements in today's rule.
As described in sections IV.A through
IV.F of this preamble, today's rule
requires PWSs to carry out the following
activities:
• Conduct initial source water
monitoring on a reported schedule.
PWSs may grandfather previously
collected monitoring results and may
elect to provide the maximum
Cryptosporidium treatment level of 5.5-
log for filtered PWSs or 3.0-log for
unfiltered PWSs instead of monitoring.
• Determine a treatment bin
classification (or mean Cryptosporidium
level for unfiltered PWSs) based on
monitoring results.
• For filtered PWSs in Bins 2-4 and
all unfiltered PWSs, provide additional
treatment for Cryptosporidium by
selecting technologies from the
microbial toolbox.
• Report disinfection profiles and
benchmarks prior to making a
significant change in disinfection
practice.
• Report the use of uncovered
finished water storage facilities and
cover or treat the discharge of such
reservoirs on a State-approved schedule.
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• Conduct a second round of source
water monitoring approximately six
years after initial bin classification.
Compliance dates for these activities
vary bv PWS size. Tables IV.G-1 and
IV.G—2 specify source water monitoring
and treatment compliance dates for
large and small PWSs, respectively.
Table IV.G—3 shows compliance dates
for PWSs using uncovered finished
water storage facilities. Wholesale PWSs
must comply with the requirements of
today's rule based on the population of
the largest PWS in the combined
distribution svstem.
TABLE IV.G-1.—MONITORING AND TREATMENT COMPLIANCE DATES FOR PWSs SERVING AT LEAST 10,000 PEOPLE
Requirement
Compliance dates by PWS Size
PWSs serving at least
100,000 people
PWSs serving at least
50,000 but less than
100,000 people
PWSs serving at least
10,000 but less than
50,000 people
Report sampling schedule and sampling location de-
scription for initial source water monitoring for
Cryptosporidium (plus E coh and turbidity at filtered
PWSs)' -.
Report notice of intent to grandfather previously col-
lected Cryptosporidium data, if applicable
Report intent to provide the maximum Cryptosporidium
treatment level in lieu of monitoring, if applicable1
Begin initial source water monitoring for
Cryptosporidium (plus E coh and turbidity at filtered
PWSs)' ^
Submit previously collected Cryptosporidium data and
required documentation for grandfathenng, if applica-
ble
Report Cryptosporidium treatment bin classification (or
mean Cryptosporidium concentration for unfiltered
PWSs) and supporting data for approval
Report disinfection profiles and benchmarks, if applica-
ble
Comply with additional Cryptosporidium treatment re-
quirements based on treatment bin classification (or
mean Cryptosporidium concentration for unfiltered
PWSs)3
Report sampling schedule and sampling location de-
scription for second round of source water monitoring
for Cryptosporidium (plus E. coli and turbidity at fil-
tered PWSs)1
Report intent to provide maximum Cryptosporidium
treatment level in lieu of monitoring, if applicable '.
Begin second round of source water monitoring for
Cryptosporidium (plus E coh and turbidity at filtered
PWSs)1.
Report Cryptosporidium treatment bin classification (or
mean Cryptosporidium concentration for unfiltered
PWSs) and supporting data from second round of
monitoring for approval
Comply with additional Cryptosporidium treatment re-
quirements if bin classification (or mean
Cryptosporidium concentration for unfiltered PWSs)
changes based on second round of monitoring
No later than July 1, 2006.
No later than January 1,
2007.
No later than January 1,
2008.
No later than the month
beginning October 1,
2006
No later than December 1,
2006.
No later than the month
beginning April 1, 2009
No later than the month
beginning April 1, 2007
No later than June 1,
2007 .
No later than the month
beginning October 1,
2009
No later than the month
beginning April 1, 2008.
No later than June 1,
2008
No later than the month
beginning October 1,
2010
Prior to making a significant change in disinfection practice.
No later than April 1,
2012 3
No later than January 1,
2015.
No later than the month
beginning April 1, 2015
No later than the month
beginning October 1,
2017.
No later than October 1,
20133.
No later than July 1, 2015
No later than the month
beginning October 1,
2015.
No later than the month
beginning April 1, 2018.
No later than October 1,
20123
No later than July 1, 2016.
No later than the month
beginning October 1,
2016
No later than the month
beginning April 1, 2019
On a schedule the State approves
1 PWS are not required to conduct source water monitoring if they submit a notice of intent to provide the maximum Cryptosporidium treatment
level. 5.5-log for filtered PWSs or 3.0-log for unfiltered PWSs
2 Not required if PWS grandfathers at least 2 years of Cryptosporidium data
3 States may grant up to an additional 2 years for systems making capital improvements.
TABLE IV.G-2.—MONITORING AND TREATMENT COMPLIANCE DATES FOR PWSs SERVING FEWER THAN 10,000 PEOPLE
Requirement
Compliance dates
Indicator (E. coli) Monitoring Requirements for Filtered PWSs Only
Report sampling schedule and sampling location description for initial
source water monitoring for E coli or alternative State-approved indi-
cator1 2
Report notice intent to grandfather previously collected E. coli data, if
applicable
Report intent to provide the maximum Cryptosporidium treatment level
in lieu of monitoring, if applicable1.
Begin initial source water monitoring for E. coli1 -
Report E coli data for grandfathenng, if applicable
No later than July 1, 2008.
No later than the month beginning October 1, 2008.
No later than December 1, 2008
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717
TABLE IV.G-2.—MONITORING AND TREATMENT COMPLIANCE DATES FOR PWSs SERVING FEWER THAN 10,000
PEOPLE—Continued
Requirement
Compliance dates
Report sampling schedule and sampling location description for second
round of source water monitoring for E. coli1.
Report intent to provide the maximum Cryptosporidium treatment level
in lieu of monitoring, if applicable1.
Begin second round of source water monitoring for E coli1.
No later than July 1, 2017.
No later than the month beginning October 1, 2017.
Requirement
Compliance dates by monitoring option
PWSs monitoring twice-per-month
for 1 year
PWSs monitoring monthly for 2
years
Cryptosporidium Monitoring Requirements for Filtered PWSs That Exceed Indicator (E. coli) Trigger Concentration3 and All Unfiltered
PWSs
Report sampling schedule and sampling location description (if not re-
ported previously) for initial source water monitoring for
Cryptosporidium'4.
Report notice of intent to grandfather previously collected
Cryptosporidium data, if applicable
Begin initial source water monitoring for Cryptosporidium14
Submit previously collected Cryptosporidium data and required docu-
mentation for grandfathenng, if applicable.
Report Cryptosporidium treatment bin classification (or mean
Cryptosporidium concentration for unfiltered PWSs) and supporting
data for approval
Report disinfection profiles and benchmarks, if applicable
Comply with additional Cryptosporidium treatment requirements based
on treatment bin classification (or mean Cryptosporidium concentra-
tion for unfiltered PWSs)5.
Report sampling schedule sampling location description (if not re-
ported previously) for second round of source water
Cryptosporidium monitoring1.
Begin second round of source water monitoring for Cryptosporidium1.
Report Cryptosporidium treatment bin classification (or mean
Cryptosporidium concentration for unfiltered PWSs) and supporting
data from second round of monitoring for approval.
Comply with additional Cryptosporidium treatment requirements if bin
classification (or mean Cryptospondium concentration for unfiltered
PWSs) changes based on second round of monitoring
No later than January 1, 2010.
No later than the month beginning April 1, 2010.
No later than June 1, 2010.
No later than the month beginning
October 1, 2011.
No later than the month beginning
October 1, 2012
Prior to making a significant change in disinfection practice.
No later than October 1, 2014 5
No later than than January 1,
2019
No later than the month beginning
April 1, 2019.
No later than the month beginning
October 1, 2020.
On a schedule the State approves
No later than the month beginning
October 1, 2021
1 PWS are not required to conduct source water monitoring if they submit a notice of intent to provide the maximum Cryptosporidium treatment
level- 5.5-log for filtered PWSs or 3.0-log for unfiltered PWSs.
2 Not required if PWS grandfathers at least 1 year of E. coli data.
3 Filtered PWSs must conduct Cryptosporidium monitoring if the E coli annual mean concentration exceeds 10/100 mL for PWSs using lake or
reservoir sources or exceeds 50/100 mL for PWSs using flowing stream sources or a trigger value for an alternative State-approved indicator is
exceeded.
4 Not required if PWS grandfathers at least 1 year of twice-per-month or 2 years of monthly Cryptosporidium data.
5 States may grant up to an additional 2 years for PWSs making capital improvements
TABLE IV.G-3.—COMPLIANCE DATES FOR PWSs USING UNCOVERED FINISHED WATER STORAGE FACILITIES
Report the use of uncovered finished water storage facilities, if applica-
ble.
Either comply with requirement to cover or treat uncovered finished
water storage facilities or comply with State-approved schedule to
meet this requirement
No later than April 1, 2008
No later than April 1, 2009
2. Background and Analysis
The compliance schedule in today's
final rule stems from its risk-targeted
approach, wherein PWSs initially
conduct monitoring to determine
additional treatment requirements. A
primary objective of this schedule is to
ensure that PWSs provide additional
treatment without delay for higher risk
sources. This is especially important
with a risk-targeted rule, given the
significant time required for initial
monitoring. However, the compliance
schedule balances this objective with
the need to provide PWSs and States
with time to prepare for implementation
activities.
SDWA section 1412(b)(10) states that
a drinking water regulation shall take
effect 3 years from the promulgation
date unless the Administrator
determines that an earlier date is
practicable. Today's rule requires PWSs
to begin monitoring prior to 3 years
from the promulgation date. Based on
EPA's assessment and recommendations
of the Advisory Committee, as described
in this section, EPA has determined that
these monitoring start dates are
practicable and appropriate.
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In general, PWSs serving at least
10,000 people conduct two years of
source water monitoring for
Cryptosporidium (as well as E. coli and
turbidity in filtered PWSs). At the
conclusion of this monitoring, these
PWSs have six months to analyze
monitoring results and report their
treatment bin classification to the State
for approval. Where required. PWSs
must provide the necessary level of
additional Cryptosporidium treatment
within three years of bin classification,
though States may allow an additional
two years for PWSs making capital
improvements. A second round of
source water monitoring must be
initiated six years after initial bin
classification.
For PWSs serving at least 10,000
people, the timing of monitoring and
treatment activities in today's rule
partially reflects recommendations by
the Stage 2 M-DBP Advisory Committee
and the schedule in the August 11, 2003
proposed LT2ESWTR. EPA has
modified the proposed compliance
schedule to stagger monitoring start
dates for PWSs serving 10.000 to 99.999
people. The following discussion
addresses these changes from the
proposal.
The proposed rule required all PWSs
serving at least 10,000 people to begin
source water monitoring six months
after the rule was established, as
recommended by the Advisory
Committee. Under today's final rule,
PWSs serving at least 100,000 people
maintain this schedule. The monitoring
start date for PWSs serving 50,000 to
99,999 people is staggered by six
months and begins 12 months after the
rule is effective. For PWSs serving
10,000 to 49,999, the monitoring start
date is staggered by 18 months and
begins 24 months after the rule is
effective. Dates to comply with
additional treatment requirements are
staggered accordingly.
This staggering of monitoring start
dates for PWSs serving 10,000 to 99,999
people is advantageous in several
respects:
• Provides more time for PWSs that
have not monitored for
Cryptosporidium previously to prepare
for monitoring (PWSs serving at least
100,000 people monitored for
Cryptosporidium under the ICR). PWSs
can use this time to develop budgets,
establish contracts with
Cryptosporidium laboratories, identify
appropriate sampling locations, and
learn sampling procedures.
• Provides more time for
Cryptosporidium analytical laboratories
to build capacity as needed to
accommodate the sample analysis needs
of PWSs.
• Spreads out the transactional
demand for regulatory oversight. EPA
anticipates that the period of greatest
transactional demand for States and
EPA that oversee monitoring will be
when PWSs begin monitoring. The
staggered schedule will allow States and
EPA to provide more assistance to
individual PWSs.
• Eliminates the gap between the end
of large PWS monitoring and the start of
small PWS monitoring (under the
proposed rule schedule, a gap of 18
months existed between the time that
large PWSs completed and small PWSs
started Cryptosporidium monitoring).
Such a gap could create difficulties with
maintaining Cryptosporidium sampling
and laboratory analysis expertise to
support monitoring by small PWSs.
The timing of monitoring and
treatment activities in today's rule for
PWSs serving fewer than 10,000 people
is nearly identical to the schedule in the
August'll, 2003 proposed LT2ESWTR
and reflects recommendations by the
Advisory Committee. The only change
is allowing these PWSs the option to
spread their Cryptosporidium
monitoring over two years in order to
facilitate budgeting for this monitoring.
However, this change does not affect the
treatment compliance dates for these
PWSs.
Specifically, filtered PWSs serving
fewer than 10,000 people initially
conduct one year of source water
monitoring for E. coli or an alternative
indicator if approved by the State,
beginning 30 months after the rule is
effective. At the conclusion of this
monitoring, these PWSs have six
months to prepare for Cryptosporidium
monitoring, if required based on their
indicator monitoring results. Filtered
PWSs that exceed the indicator trigger
value and all unfiltered PWSs serving
fewer than 10,000 people must begin
Cryptosporidium monitoring 48 months
after the rule is effective. This
Cryptosporidium monitoring may
consist of sampling twice-per-month for
one year or once-per-month for two
years. PWSs must report their bin
classification to the State for approval
within six months of the scheduled
completion of Cryptosporidium
monitoring.
Regardless of the Cryptosporidium
sampling frequency, PWSs serving
fewer than 10,000 people must comply
with any additional Cryptosporidium
treatment requirements within 102
months (8.5 years) after the rule is
effective. States may allow an additional
two years for PWSs making capital
improvements. PWSs must begin a
second round of source water
monitoring for E. coli or an alternative
State-approved indicator within 11.5
years (138 months) after the rule is
effective (six years after the bin
classification date for PWSs that
sampled for Cryptosporidium twice-per-
month during initial source water
monitoring).
In summary, the compliance schedule
for today's rule maintains the earliest
compliance dates recommended by the
Advisory Committee for PWSs serving
at least 100,000 people. These PWSs
serve the majority of people that
consume water from surface sources.
The schedule also maintains the latest
compliance dates the Advisory
Committee recommended, which apply
to PWSs serving fewer than 10,000
people. EPA has staggered compliance
schedules for PWSs between these two
size categories in order to facilitate
implementation of the rule.
3. Summary of Major Comments
EPA received significant public
comment on the compliance schedule in
the August 11, 2003 proposal. Major
issues raised by commenters include
providing more time for PWSs to
prepare for monitoring, giving States
more time to oversee monitoring.
ensuring that laboratory capacity can
accommodate the compliance schedule,
and establishing consistent schedules
for consecutive PWSs. A summary of
these comments and EPA's responses
follows.
Commenters were concerned that
some PWSs, in particular PWSs serving
10,000 to 50,000 people, would need
more than the three months allowed
under the proposed rule to report
sampling schedules for monitoring. In
order to develop sampling schedules,
PWSs must establish contracts with
laboratories, which may involve using
municipal procurement procedures. For
smaller PWSs, budgeting for this
expense may require substantial time
and planning.
EPA recognizes this concern and
today's final rule provides significantly
more time for many PWSs to submit
sampling schedules. Specifically, PWSs
serving 50,000 to 99,999 people and
those serving 10,000 to 49,999 people
must submit sampling schedules 9 and
21 months after the rule is effective,
respectively. EPA believes that these
PWSs will have sufficient time to
develop sampling schedules with these
compliance dates. Today's rule still
requires PWSs serving at least 100,000
people to submit sampling schedules 3
months after the rule is effective.
Because these PWSs have monitored for
Cryptosporidium previously, however,
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719
EPA believes that this compliance date
is feasible for these PWSs.
Several commenters recommended
that States, rather than EPA, oversee
monitoring due to States' existing
relationships with and knowledge of
their PWSs. Commenters were
concerned that some States will not
participate in early implementation
activities and indicated that States
would prefer monitoring to begin 24
months after rule promulgation. States
need sufficient time to become familiar
with the rule, train their staff, prepare
primacy packages, and train PWSs.
In general, EPA would prefer that
States oversee monitoring by their PWSs
and will work with States to facilitate
their involvement with rule
implementation. Where States are
unable to implement today's rule,
however, EPA is prepared to oversee
implementation. Moreover, EPA
believes that the staggered compliance
schedule in today's final rule will
enhance States' ability to implement the
rule.
While EPA does not consider waiting
until 24 months after rule promulgation
to start monitoring for all PWSs to be
appropriate, most PWSs will not begin
monitoring until this time or later under
today's rule. Among large PWSs (i.e.,
those serving at least 10,000 people), the
majority are in the 10,000 to 49,999
person size category and these PWSs do
not begin monitoring until 24 months
after rule promulgation. Further, all
PWSs serving fewer than 10,000 people
do not begin monitoring until 30
months after rule promulgation. These
smaller PWSs are likely to need the
most assistance from States. By
staggering monitoring start dates,
today's rule also reduces the number of
PWSs that will begin monitoring at any
one time, when the most assistance from
regulatory agencies will be required.
Many commenters were concerned
that the capacity at Cryptosporidium
analytical laboratories would not be
sufficient for the proposed
implementation schedule. Commenters
noted that the proposed rule schedule
had a break of 18 months between the
end of large PWS Cryptosporidium
monitoring and the start of small PWS
Cryptosporidium monitoring and
thought that this break would
discourage laboratories from making
investments to improve capacity. Other
commenters stated that excess .
laboratory capacity exists and that upon
indication that a final rule is imminent,
commercial laboratories will hire staff to
handle the expected number of samples.
Laboratories will, however, need time to
train analysts.
EPA recognizes the concern with
ensuring that capacity at
Cryptosporidium laboratories will be
sufficient. Through EPA's laboratory
approval program (described in section
IV.K), the Agency has evaluated
capacity at Cryptosporidium
laboratories. Based on information
provided by laboratories, EPA believes
that current capacity at
Cryptosporidium laboratories will be
sufficient for the monitoring that PWSs
serving at least 100,000 people-will
begin six months after the rule is
effective. EPA expects that commercial
laboratories will increase capacity as
needed to serve the demand of smaller
PWSs that begin monitoring later.
Approximately six months are required
to train Cryptosporidium analysts.
Consequently, the staggered compliance
schedule should allow time for
laboratories to hire and train staff as
necessary. In addition, with the
compliance schedule in today's final
rule, no break exists between the time
that large PWSs end and small PWSs
begin Cryptosporidium monitoring.
Thus, EPA has eliminated this potential
disincentive to laboratories investing in
capacity.
However, EPA will continue to
monitor laboratory capacity and the
ability of PWSs to contract with
laboratories to meet their monitoring
requirements under the LT2ESWTR.
The Agency will assist with
implementation of the rule to help
maximize the use of available laboratory
capacity by PWSs. If evidence emerges
during implementation of the rule that
PWSs are experiencing problems with
insufficient laboratory capacity, the
Agency will undertake appropriate
action at that time.
In regard to consecutive PWSs (i.e.,
PWSs that buy and sell treated water),
commenters recommended that
compliance schedules in the Stage 2
DBPR and LT2ESWTR should be
consistent. Some commenters also
suggested that where a small PWS sells
water to a large PWS, the small PWS
should comply on the large PWS
schedule. In response, today's final rule
requires PWSs that sell treated drinking
water to other PWSs to comply
according to the schedule that applies to
the largest PWS in the combined
distribution system. This approach will
ensure that PWSs have the same
compliance schedule under both the
LT2ESWTR and Stage 2 DBPR.
H. Public Notice Requirements
1. Today's Rule
Today's rule establishes the following
public notice requirements:
• For violations of treatment
technique requirements, which today's
rule establishes for Cryptosporidium
treatment and for covering or treating
uncovered finished water reservoirs,
PWSs must issue a Tier 2 public notice
and must use existing health effects
language (except as provided below) for
microbiological contaminant treatment
technique violations, as stated in 40
CFR 141 Subpart Q, Appendix B.
• For violations of monitoring and
testing procedure requirements,
including the failure to collect one or
two source water Cryptosporidium
samples, PWSs must issue a Tier 3
public notice. If the State determines
that a PWS has failed to collect three or
more Cryptosporidium samples, the
PWS must provide a Tier 2 special
public notice. Violations for failing to
monitor continue until the State
determines that the PWS has begun
sampling on a revised schedule that
includes dates for collection of missed
samples. This schedule may also
include a revised bin determination date
where necessary.
• PWSs must report their bin
classification no later than six months
after the end of the scheduled
monitoring period (specific dates in
section IV.G.). Failure by a PWS to
collect the required number of
Cryptosporidium samples to report its
bin classification by the compliance
date is a treatment technique violation
and the PWS must provide a Tier 2
public notice. The treatment technique
violation persists until the State
determines that the PWS is
implementing a State-approved
monitoring plan to allow bin
classification or will install the highest
level of treatment required under the
rule. If the PWS has already provided a
Tier 2 special public notice for missing
3 sampling dates and is successfully
meeting a State-approved schedule for
sampling and bin determination, it need
not provide a second Tier 2 notice for
missing the bin determination deadline
in today's rule.
2. Background and Aalysis
In 2000, EPA published the Public
Notification Rule (65 FR 25982, May 4,
2000) (USEPA 2000b), which revised
the general public notification
regulations for PWSs in order to
implement the public notification
requirements of the 1996 SDWA
amendments. This regulation
established the requirements that PWSs
must follow regarding the form, manner,
frequency, and content of a public
notice. Public notification of violations
is an integral part of the public health
protection and consumer right-to-know
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provisions of the 1996 SDWA
Amendments.
Owners and operators of PWSs are
required to notify persons served when
they fail to comply with the
requirements of a NPDWR, have a
variance or exemption from the drinking
water regulations, or are facing other
situations posing a risk to public health.
The public notification requirements
divide violations into three categories
(Tier 1, Tier 2 and Tier 3) based on the
seriousness of the violations, with each
tier having different public notification
requirements.
EPA has limited its list of violations
and situations routinely requiring a Tier
1 notice to those with a significant
potential for serious adverse health
effects from short term exposure. Tier 1
violations contain language specified by
EPA that concisely and in non-technical
terms conveys to the public the adverse
health effects that may occur as a result
of the violation. States and water
utilities may add additional information
to each notice, as deemed appropriate
for specific situations. A State may
elevate to Tier 1 other violations and
situations with significant potential to
have serious adverse health effects from
short-term exposure, as determined by
the State.
Tier 2 public notices address other
violations with potential to have serious
adverse health effects on human health.
Tier 2 notices are required for the
following situations:
• All violations of the MCL,
maximum residual disinfectant level
(MRDL) and treatment technique
requirements, except where a Tier 1
notice is required or where the State
determines that a Tier 1 notice is
required; and
• Failure to comply with the terms
and conditions of any existing variance
or exemption. Tier 3 public notices
include all other violations and
situations requiring public notice,
including the following situations:
• A monitoring or testing procedure
violation, except where a Tier 1 or 2
notice is already required or where the
State has elevated the notice to Tier 1
or 2; and
• Operation under a variance or
exemption.
The State, at its discretion, may
elevate the notice requirement for
specific monitoring or testing
procedures from a Tier 3 to a Tier 2
notice, taking into account the potential
health impacts and persistence of the
violation.
As part of the IESWTR, EPA
established health effects language for
violations of treatment technique
requirements for microbiological
contaminants. EPA believes this
language, which was developed with
consideration of Cryptosporidium
health effects, is appropriate for
violations of some Cryptosporidium
treatment requirements under the
LT2ESWTR. However, for persistent
monitoring violations and missing the
deadline for bin determination, EPA is
promulgating alternative language that
better informs consumers of the nature
and potential health consequences of
the violation.
As described in section IV.C. EPA
proposed automatically classifying
PWSs in the highest treatment bin (Bin
4) if they fail to complete required
monitoring. For today's final rule, EPA
has determined that providing more
flexibility to States in dealing with
PWSs that fail to monitor is appropriate.
EPA also believes, however, that
responses to monitoring failures must
reasonably ensure that PWSs complete
monitoring as required to determine a
bin classification within the compliance
date, or as soon thereafter as possible.
Moreover, consistent with the public
health protection and consumer right-to-
know provisions of the 1996 SDWA
Amendments, consumers should be
informed of these monitoring failures.
Instead of the proposed automatic Bin
4 classification for monitoring failures
under today's rule, PWSs must provide
a Tier 3 public notice for monitoring
violations including up to two missed
Cryptosporidium samples. If a PWS
misses three or more Cryptosporidium
samples (other than the specifically
exempted situations described in
section IV.A.l.c), this persistent
violation requires a Tier 2 public notice.
This elevated public notice level reflects
significant concern that persistent
failure to collect required samples will
result in the PWS being unable to
determine its Cryptosporidium
treatment bin classification and the
corresponding required treatment level
by the compliance date.
Further, if a PWS is unable to
determine a bin classification by the
compliance date due to failure to collect
the required number of
Cryptosporidium samples, this is a
treatment technique violation that also
requires a Tier 2 public notice, unless
the system is already complying with an
alternate State-approved schedule for
monitoring and bin determination. A
PWS that does not determine its bin
classification by the required date may
not be able to comply with the
Cryptosporidium treatment technique
requirements of today's rule by the
required date and provide the
appropriate level of public health
protection.
3. Summary of Major Comments
In the August 11. 2003, proposal, EPA
requested comment on whether
violations of the treatment requirements
for Cryptosporidium under the
LT2ESWTR should require a Tier 2
public notice and whether the proposed
health effects language is appropriate
(USEPA 2003a). Most commenters
supported requiring a Tier 2 public
notice for violations of Cryptosporidium
treatment requirements under the
LT2ESWTR and agreed that no new
health effects language is needed for this
notification. One commenter stated that
a failure to meet Cryptosporidium
removal requirements under
LT2ESWTR should require Tier 1 public
notice.
Today's final rule reflects the views of
most commenters and is consistent with
existing regulations in requiring a Tier
2 public notice for Cryptosporidium
treatment technique violations. A State
may elevate a violation to Tier 1 if the
State determines that the violation
creates significant potential for serious
adverse health effects from short-term
exposure.
Another commenter agreed that Tier 2
notice was appropriate but
recommended that the LT2ESWTR and
any associated guidance be more
explicit as to when a treatment
technique violation occurs with the use
of microbial toolbox options. As
described in section IV.D, EPA has
stated in today's final rule that failure
by a PWS in any month to demonstrate
treatment credit with microbial toolbox
options equal to or greater than its
Cryptosporidium treatment
requirements is a treatment technique
violation. This violation lasts until the
PWS demonstrates that it is meeting
criteria for sufficient treatment credit to
satisfy its Cryptosporidium treatment
requirements.
I Reporting Source Water Monitoring
Results
This section presents specific
reporting requirements that apply to
source water monitoring under today's
rule, including EPA's data system for
reporting and reviewing monitoring
results. For related requirements, see
section IV.A for monitoring parameters
frequency, section IV.) for required
analytical methods, and section IV.K for
approved laboratories. General reporting
requirements under today's rule and
associated compliance dates are shown
in section IV.G.
1. Today's Rule
PWSs must report results from the
required source water monitoring
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
721
described in section IV. A no later than
10 days after the end of the first month
following the month when the sample is
collected. For Cryptosporidium
analyses, PWSs must report the data
elements specified in Table IV.I-1. For
samples in which at least 10 L is filtered
and all of the sample volume is
analyzed, only the sample volume
filtered and the number of oocysts
counted must be reported. Table IV.I—2
presents the data elements that PWSs
must report for E. coli and turbidity
analyses. PWSs, or approved
laboratories acting as the PWSs' agents,
must retain results from
Cryptosporidium and E. coli monitoring
until 36 months after bin determination
for the particular round of monitoring.
TABLE IV.1-1.—CRYPTOSPORIDIUM DATA ELEMENTS To BE REPORTED
Data element
Reason for data
element
Identifying information:
PWSID
Facility ID
Sample collection point
Sample collection date .
Sample type (field or matrix spike)'
Sample results-
Sample volume filtered (L), to nearest V* L 2
Was 100% of filtered volume examined9 3 ...
Number of oocysts counted
Needed to associate plant with public water system.
Needed to associate sample result with facility.
Needed to associate sample result with sampling point.
Needed to determine that utilities are collecting samples at the fre-
quency required.
Needed to distinguish field samples from matrix samples for recovery
calculations.
Needed to verify compliance with sample volume requirements
Needed to calculate the final concentration of oocysts/L and determine
if volume analyzed requirements are met
Needed to calculate the final concentration of oocysts/L
1 For matrix spike samples, sample volume spiked and estimated number of oocysts spiked must be reported. These data are not required for
field samples.
2For samples in which <10 L is filtered or <100% of the sample volume is examined, the number of filters used and the packed pellet volume
must also be reported to verify compliance with LT2ESWTR sample volume analysis requirements. These data are not required for most sam-
ples.
3 For samples in which <100% of sample is examined, the volume of resuspended concentrate and volume of this resuspension processed
through IMS must be reported to calculate the sample volume examined. These data are not required for most samples
TABLE IV.I-2.—E. COLI AND TURBIDITY DATA ELEMENTS To BE REPORTED
Data element
Reason for collecting data element
Identifying Information-
PWS ID
Facility ID
Sample collection point
Sample collection date .
Analytical method number
Method Type
Source water type
E. coh/100 mL
Turbidity Information:
Turbidity result ...
Needed to associate analytical result with public water system.
Needed to associate plant with public water system.
Needed to associate sample result with sampling point
Needed to determine that utilities are collecting samples at the fre-
quency required
Needed to associate analytical result with analytical method.
Needed to verify that an approved method was used and call up cor-
rect web entry form
Needed to assess Cryptosporidium indicator relationships
Sample result (although not required, the laboratory also will have the
option of entering primary measurements for a sample into the
LT2ESWTR internet-based database to have the database automati-
cally calculate the sample result).
Needed to assess Cryptosporidium indicator relationships
PWSs serving at least 10,000 people
must submit sampling schedules
(described in section IV. A) and
monitoring results for the initial source
water monitoring to EPA electronically
at the following Internet site: https://
intranet.epa.gov/lt2/. These PWSs
should instruct their laboratories to
electronically enter results at this site
using web-based manual entry forms or
by uploading XML files (extensible
markup language files—a standard
format that enables information
exchange between different systems)
from laboratory information
management systems (LIMS). After
laboratories enter sample results, PWSs
must review the results on-line at this
site. The State may approve an
alternative approach for reporting
source water monitoring schedules and
sample results if, for example, a PWS or
laboratory does not have the capability
to report data electronically.
If a PWS believes that its laboratory
entered a sample result into the data
system erroneously, the PWS may notify
the laboratory to rectify the entry. In
addition, if a PWS believes that a result
is incorrect, the PWS may electronically
mark the result as contested and
petition the State to invalidate the
sample. If a PWS contests a sample
result, the PWS should submit a
rationale to the State, including a
supporting statement from the
laboratory, providing a justification.
PWSs may arrange with laboratories to
review their sample results prior to the
results being entered into the EPA data
system.
PWSs serving fewer than 10,000
people must submit sampling schedules
and monitoring results for the initial
round of source water monitoring to the
State. Further, all PWSs must submit
sampling schedules and monitoring
results for the second round of
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
monitoring to the State. Regardless of
the reporting process used, PWSs must
report an analytical monitoring result to
the State no later than 10 days after the
end of the first month following the
month when the sample was collected.
2. Background and Analysis
The reporting requirements for source
water monitoring in today's final rule
reflect those in the August 11, 2003
proposed LT2ESWTR (USEPA 2003a).
The data elements that PWSs must
report for Cryptosporidium and E. coli
analyses are the minimum necessary to
identify the sample, determine the
sample concentration, and verify that
the PWS complied with rule
requirements like minimum sample
volume and approved analytical
methods. PWSs or laboratories must
keep bench sheets and slide reports for
Cryptosporidium analyses for three
years after bin determination for the
particular round of monitoring, at which
time PWSs must be in compliance with
any additional Cryptosporidium
treatment requirements based on the
monitoring results.
Due to the early implementation
schedule, EPA expects to partner with
States to implement initial source water
monitoring by large PWSs under today's
rule. EPA has developed an Internet-
based data system to allow electronic
reporting and review of source water
monitoring results by laboratories,
PWSs, States, and EPA. States may use
this data system to oversee monitoring
by their PWSs. Where States are unable
to provide this oversight, the data
system will allow EPA to implement
today's rule. Accordingly, PWSs serving
at least 10,000 people must use this data
system to report sampling schedules
and sample results for the initial round
of source water monitoring unless the
State approves an alternative method for
reporting.
EPA expects laboratories to report
analytical results for Cryptosporidium,
E. coli. and turbidity analyses directly to
the data system using web forms and
software that are available free of
charge. The data system will perform
logic checks on data entered and will
calculate results from primary data
where necessary. This is intended to
reduce reporting errors and limit the
time involved in investigating,
checking, and correcting errors at all
levels. The LT2ESWTR proposal
describes the analysis functions of the
data system in more detail (USEPA
2003a).
In general, EPA expects that States
will implement the initial source water
monitoring by small PWSs and the
second round of monitoring by all
PWSs. Thus, PWSs must submit
sampling schedules and monitoring
results for this monitoring to the State.
Note that where States do not assume
primacy for the rule, however, EPA will
act as the State.
3. Summary of Major Comments
EPA received significant public
comment on the following aspects of
reporting requirements for source water
monitoring in the August 11, 2003
proposed LT2ESWTR: the deadline for
reporting sample results, EPA's
electronic data system, and reporting
results to EPA rather than the State. A
summary of these comments and EPA's
responses follows.
Some commenters were concerned
with requiring PWSs to report sample
results no later than the 10th of the
second month after the month when the
sample is collected. Commenters stated
that this will cause most PWSs to
sample in the first part of the month,
which will exacerbate laboratory
capacity problems. As an alternative,
commenters recommended that PWSs
be required to report sample results 72
days after collection. This approach
would give all PWSs the same time
period to report sample results
regardless of the collection date and
would facilitate PWSs and laboratories
scheduling sample collection dates
more uniformly throughout the month.
In response, EPA believes that
requiring PWSs to report monitoring
results by the 10th of the second month
after sample collection is appropriate.
This will maintain consistency with
existing drinking water regulations,
which typically require monitoring
results to be reported by the 10th of the
following month. Thus, specifying this
reporting date under today's rule will
avoid causing PWSs and States to
develop different reporting dates for
different regulations. Due to the time
required for laboratories to analyze
Cryptosporidium samples, today's rule
gives PWSs an extra month to report
monitoring results; i.e., the minimum
time PWSs have to report results is
approximately 40 days (one month plus
10 days). This time frame, however, is
greater than what is necessary for
laboratories to analyze samples and for
PWSs to review results. Consequently,
EPA does not believe that PWSs will
benefit by collecting a sample at the
start of a month in comparison to the
end of a month.
Many commenters expressed concern
with trie readiness of the electronic data
system for reporting and reviewing
monitoring results under today's rule.
Commenters stated that PWSs have
experienced significant problems with
data systems that supported earlier
rules, such as the Information Collection
Rule and the Unregulated Contaminant
Monitoring Rule. Commenters
recommended that the data system be in
place and fully tested prior to
finalization of the rule and that EPA
provide training for users. If the data
system is not available when the rule is
finalized, commenters asked that the
monitoring be delayed as specified in
the Agreement in Principle (USEPA
2000a).
EPA has ensured that the LT2 data
system has been fully tested and
deployed prior to finalizing the rule.
During development of the data system,
EPA has involved stakeholders in a joint
requirements workgroup, which has
made recommendations for data system
characteristics and has participated in
data system testing. EPA has developed
guidance and other training materials
for PWSs, States, and laboratories on
how to use the data system and will
provide technical assistance on a
ongoing basis to data system users. EPA
believes these steps will help to avoid
problems that stakeholders experienced
with data systems for earlier rules.
Some commenters expressed concerns
about large PWSs reporting monitoring
results to EPA. Commenters stated that
implementation of the rule should be
administered by States, due to the
existing relationships States have with
the PWSs they regulate. For States that
will implement the rule, commenters
recommended allowing PWSs to report
to States, rather than EPA. Commenters
also requested that EPA provide copies
of all monitoring data and PWS
correspondence to States when they
assume primacy.
EPA will work with States to
implement today's rule and to help
States assume as much responsibility for
implementation as they can. Through
the LT2ESWTR data system, States will
have full access to monitoring results
reported by their PWSs. Today's rule
also allows States to direct their PWSs
to report monitoring results directly to
them, rather than EPA. Further, States
may require PWSs to submit
descriptions of monitoring locations for
approval. In general, EPA will seek to
involve States in any communications
with and decisions for their PWSs and
will allow States to take responsibility
for these activities if they choose to do
so. However, because monitoring for the
largest systems begins before States will
have had time to assume primacy, EPA
must be prepared to oversee monitoring
for these PWSs where States are unable
to do so.
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
723
/. Analytical Methods
1. Analytical Methods Overview
Today's final rule requires public
water systems to conduct LT2ESWTR
source water monitoring using approved
methods for Cryptosporidium, E. coli,
and turbidity analyses. PWSs must meet
the quality control criteria stipulated by
the approved methods and additional
method-specific requirements, as stated
in this section. Related requirements for
reporting source water monitoring
results and using approved laboratories
are discussed in sections IV.I and IV.K,
respectively.
EPA has developed guidance for
sampling and analyses under the
LT2ESWTR. The Source Water
Monitoring Guidance Manual for Public
Water Systems under the LT2ESWTR
provides recommendations on activities
like collecting samples and setting up
contracts with laboratories. The
Microbial Laboratory Manual for the
LT2ESWTR provides information for
laboratories that conduct analyses.
These guidance documents may be
requested from EPA's Safe Drinking
Water Hotline, which may be contacted
as described in the FOR FURTHER
INFORMATION CONTACT section in the
beginning of this notice, and are
available on the Internet at
www.epa.gov/safewater/disinfec.tion/lt2.
2. Cryptosporidium Methods
a. Today's Rule
Cryptosporidium analysis for source
water monitoring under today's rule
must be conducted using either Method
1622: Cryptosporidium in Water by
Filtration/IMS/FA (EPA 815-R-05-001,
USEPA 2005c) or Method 1623:
Cryptosporidium and Giardia in Water
by Filtration/IMS/FA (EPA 815-R-05-
002, USEPA 2005d). Additional method
requirements for today's rule include
the following:
• For each Cryptosporidium sample,
at least a 10-L sample volume must be
analyzed unless a PWS meets one of the
two exceptions stated in this section.
PWSs may collect and analyze greater
than a 10-L sample volume.
• The first exception to the sample
volume requirement stems from sample
turbidity. If a sample is very turbid, it
may generate a large packed pellet
volume upon centrifugation (a packed
pellet refers to the concentrated sample
after centrifugation has been performed
in EPA Methods 1622 and 1623).
Samples resulting in large packed
pellets must have the sample
concentrate aliquoted into multiple
"subsamples" for independent
processing through IMS, staining, and
examination. PWSs are not required to
analyze more than 2 mL of packed pellet
volume per sample.
• The second exception to the sample
volume requirement stems from filter
clogging. In cases where the filter clogs
prior to filtration of 10 L, the PWS must
analyze as much sample volume as can
be filtered by 2 filters, up to a packed
pellet volume of 2 mL. This condition
applies only to filters that have been
approved by EPA for nationwide use
with Methods 1622 and 1623—the Pall
Gelman Envirochek™ and
Envirochek™ HV filters, the IDEXX
Filta-Max™ foam filter, and the
Whatman CrypTest™ cartridge filter.
• Methods 1622 and 1623 include
fluorescein isothiocyanate (FITC) as the
primary antibody stain for
Cryptosporidium detection, DAPI
staining to detect nuclei, and DIG to
detect internal structures. Under today's
rule, PWSs must report total
Cryptosporidium oocysts as detected by
FITC as determined by the color (apple
green or alternative stain color approved
for the laboratory under the Lab QA
Program described in section IV.K), size
(4-6 micrometers) and shape (round to
oval). This total includes all of the
oocysts identified as described here, less
any atypical organisms identified by
FITC, DIG, or DAPI (e.g., possessing
spikes, stalks, appendages, pores, one or
two large nuclei filling the cell, red
fluorescing chloroplasts, crystals,
spores, etc.).
• As required by Method 1622 and
1623, PWSs must have 1 matrix spike
(MS) sample analyzed for each 20
source water samples. The volume of
the MS sample must be within ten
percent of the volume of the unspiked
sample that is collected at the same
time, and the samples must be collected
by splitting the sample stream or
collecting the samples sequentially. The
MS sample and the associated unspiked
sample must be analyzed by the same
procedure. MS samples must be spiked
and filtered in the laboratory. However,
if the volume of the MS sample is
greater than 10 L, the PWS is permitted
to filter all but 10 L of the MS sample
in the field, and ship the filtered sample
and the remaining 10 L of source water
to the laboratory. In this case, the
laboratory must spike the remaining 10
L of water and filter it through the filter
that was used to collect the balance of
the sample in the field.
• Laboratories must use flow
cytometer-counted spiking suspensions
for spiked QC samples.
b. Background and Analysis
The M-DBP Advisory Committee
recommended the use of Methods 1622
or 1623 and a minimum sample volume
of 10 L for source water
Cryptosporidium analyses under the
LT2ESWTR. The August 11, 2003
proposed rule reflected these
recommendations, with associated QC
requirements and exceptions to the
minimum sample volume for samples
that are highly turbid or cause
significant filter clogging (USEPA
2003a). Today's final rule is unchanged
from the proposal in these respects.
Today's rule requires the use of
methods 1622 or 1623 because they are
the best available methods that have
undergone full validation testing. As
described in section III.E, these methods
were used during the ICRSS, where MS
samples indicated a mean recovery and
relative standard deviation of 43 and 47
percent, respectively (Connell et al.
2000). EPA expects that PWSs will
achieve comparable performance with
these methods during source water
monitoring under today's rule. With the
minimum sample volume and QC
requirements in today's rule, this level
of performance will be sufficient to
assign PWSs to Cryptosporidium
treatment bins and realize the public
health goals intended by EPA and the
Advisory Committee for the
LT2ESWTR. EPA has also approved
these methods for ambient water
monitoring under a separate rulemaking
(68 FR 43272, July 21, 2003) (USEPA
2003b).
The proposed LT2ESWTR required
the use of April 2001 versions of
Methods 1622 or 1623 and requested
comment on approving revised versions
of these methods in the final rule
(USEPA 2003a). The revised methods
were included in the proposal as draft
June 2003 versions. The revisions in
these versions included increased
flexibility in some QC requirements,
clarification of certain method
procedures, an increase in the allowable
sample storage temperature to 10°C, the
addition of several approved analysis
modifications, and other refinements
(see the proposed rule for
detailsKUSEPA 2003a).
Today's rule requires the use of the
revised versions of Methods 1622 and
1623. In the versions of these methods
finalized with today's rule, the upper
temperature limit for sample receipt has
been increased to 20°C. This change
responds to public comment and recent
publications (Ware and Schafer 2005,
Francy et al. 2004, Nichols et al. 2004).
As described in section IV.A, PWSs may
grandfather data generated with earlier
approved versions of these methods
(i.e., 1999 or 2001 versions).
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
c. Summary of Major Comments
Public comment on the August 11,
2003 proposed LT2ESWTR supported
approval of the revised versions of
Methods 1622 and 1623, which today's
rule establishes for source water
Cryptosporidium monitoring. EPA also
received comment regarding the lack of
viability and infectivity information
with these methods and requirements
for analyzing QC samples.
Several commenters were concerned
that Methods 1622 and 1623 do not
indicate whether a Cryptosporidium
oocyst is viable and infectious. While
EPA recognizes that these methods do
not provide information on
Cryptosporidium infectivity, EPA's
analysis indicates that they can perform
effectively for identifying those PWSs
that should provide additional
Cryptosporidium treatment (USEPA
2005a). This analysis is based on the
actual performance of these methods in
the ICRSS. Further, EPA and the M-DBP
Advisory Committee, which
recommended Methods 1622 and 1623,
accounted for this lack of information
on infectivity when designing the
Cryptosporidium treatment bins in
today's rule. EPA has not identified any
feasible methods for quantifying
Cryptosporidium infectivity in a
national monitoring program.
Several commenters suggested that
laboratories should only be required to
perform one OPR test per day instead of
one for every 20 samples, as Methods
1622 and 16*23 require. EPA believes,
however, that the frequency of one OPR
test per 20 samples is appropriate for
identifying and correcting problems. For
example, if an OPR test is performed
once per day for a laboratory that
processes 60 samples per day, a problem
that occurs at sample 10 will be
continued through the next 50 samples.
If an OPR test is performed once per 20
samples, a problem that occurs at
sample 10 would only affect 10
additional samples. Consequently, EPA
is maintaining the current QC criteria in
Methods 1622 and 1623.
3. E. coli Methods
a. Today's Rule
For enumerating source water E. coli
density under the LT2ESWTR. EPA is
approving the same methods that are
currently approved for ambient water
monitoring under 40 CFR 136.3. EPA
established these methods through the
rulemaking "Guidelines Establishing
Test Procedures for the Analysis of
Pollutants; Analytical Methods for
Biological Pollutants in Ambient Water"
(USEPA 2003b). Table IV.J-1
summarizes these methods. Method
identification numbers are provided for
applicable standards published by EPA
and voluntary consensus standards
bodies including Standard Methods.
American Society of Testing Materials
(ASTM). and the Association of
Analytical Chemists (AOAC).
TABLE IV.J-1 .—LIST OF APPROVED ANALYTICAL METHODS FOR E. COLI
Method
MPN2^4 multiple tube
Multiple tube/multiple well
MF2 ^ l2 n 14 two step, or .. .
Single step
EPA
1103 1 lf> ..
160318
1604''*
Standard Methods 18th,
19th, 20th Ed.
9221 B. 1/9221 FSh7
9223B * *
9222B/9222GS ^ 92130s
ASTM
D5392-9317
AOAC
991 15M
Other
Cohlertk s lo Colilert-
•) 8 * x i o 1 1 .
mColiBlue 24 2"
1 Recommended for enumeration of E coli in ambient water only, number per 100 ml.
2Tests must be conducted to provide organism enumeration (density) Select the appropriate configuration of tubes/filtrations and dilutions/vol-
umes to account for the quality, character, consistency, and anticipated organism density of the water sample
'To assess the comparability of results obtained with individual methods, it is suggested that side-by-side tests be conducted across seasons
of the year with the water samples routinely tested in accordance with the most current Standard Methods for the Examination of Water and
Wastewater or EPA alternate test procedure (ATP) guidelines.
4 Samples shall be enumerated by the multiple-tube or multiple-well procedure Using multiple-tube procedures, employ an appropriate tube
and dilution configuration of the sample as needed and report the Most Probable Number (MPN) Samples tested with Colilertk may be enumer-
ated with the multiple-well procedures, Quanti-trayk, or Quanti-tray'k 2000, and the MPN calculated from the table provided by the manufacturer.
5APHA 1998, 1995, 1992 Standard Methods for the Examination of Water and Wastewater. American Public Health Association 20th, 19th,
and 18th Editions. Amer Publ. Hlth. Assoc , Washington, DC.
6The multiple-tube fermentation test is used in 9221 .B 1. Lactose broth may be used in lieu of lauryl tryptose broth (LTB), if at least 25 parallel
tests are conducted between this broth and LTB using the water samples normally tested, and this comparison demonstrates that the false-posi-
tive rate and false-negative rate for total coliform using lactose broth is less than 10 percent. No requirement exists to run the completed phase
on 10 percent of all total coliform-positive tubes on a seasonal basis
7 After prior enrichment in a presumptive medium for total coliform using 9221B 1, all presumptive tubes or bottles showing any amount of gas,
growth or acidity within 48± 3 h of incubation shall be submitted to 9221F. Commercially available EC-MUG media or EC media supplemented in
the laboratory with 50 ng/ml of MUG may be used
sThese tests are collectively known as defined enzyme substrate tests, where, for example, a substrate is used to detect the enzyme glucu-
ronidase produced by E. coli.
yAOAC 1995. Official Methods of Analysis of AOAC International, 16th Edition, Volume 1, Chapter 17 Association of Official Analytical Chem-
ists International 481 North Frederick Avenue, Suite 500, Gaithersburg, Maryland 20877-2417
"'Descriptions of the Colilert*, Colilert-18*, Quanti-Tray" and Quanti-Tray'k 2000 may be obtained from IDEXX Laboratories, Inc., One IDEXX
Drive, Westbrook, Maine 04092.
11 Colilert-18* is an optimized formulation of the Colilert*' for the determination of total coliforms and E. coli that provides results within 18 h of
incubation at 35 °C rather than the 24 h required for the Colilert* test and is recommended for marine samples
12 A 0.45 (im membrane filter (MF) or other pore size certified by the manufacturer to fully retain organisms to be cultivated and to be tree of
extractables which could interfere with their growth
n Because the MF technique usually yields low and variable recovery from chlorinated wastewaters, the Most Probable Number method will be
required to resolve any controversies.
14When the MF method has not been used previously to test ambient water with high turbidity, large number of noncoliform bacteria, or sam-
ples that may contain organisms stressed by chlorine, a parallel test should be conducted with a multiple-tube technique to demonstrate applica-
bility and comparability of results
15 Subject total coliform positive samples as determined by 9222B or other membrane filter procedure to 9222G using NA-MUG media
16 USEPA 2002c. Method 1103 V Eschenchia coli (E coli) In Water By Membrane Filtration Using membrane-Thermotolerant Eschenchia coli
Agar (mTEC) U S. Environmental Protection Agency, Office of Water, Washington, DC. EPA-821-R-02-020.
17 ASTM. 2000, 1999, 1996. Annual Book of ASTM Standards—Water and Environmental Technology Section 11.02. American Society for
Testing and Materials 100 Barr Harbor Drive, West Conshohocken, PA 19428.
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
725
18USEPA. 2002 Method 1610. Eschenchia coli (E coli) In Water By Membrane Filtration Using Modified membrane-Thermotolerant Esch-
enchia coli Agar (modified mTEC) U.S. Environmental Protection Agency, Office of Water, Washington, DC EPA-821-R-02-023.
'" Preparation and use of Ml agar with a standard membrane filter procedure is set forth in the article, Brenner et al 1993. "New Medium for
the Simultaneous Detection of Total Coliform and Eschenchia coli in Water." Appl. Environ Microbiol. 59:3534-3544 and in USEPA. 2002. Meth-
od 1604: Total Coliforms and Escherichia coli (E. coli) in Water by Membrane Filtration by Using a Simultaneous Detection Technique (Ml Me-
dium) U.S. Environmental Protection Agency, Office of Water, Washington, DC EPA-821-R-02-024.
-u A description of the mColiBlue24 test, Total Coliforms and E. coli, is available from Hach Company, 100 Dayton Ave., Ames, IA 50010
For most PWSs, the time from sample
collection to initiation of analysis (i.e.,
the holding time) for source water E.
coli samples may not exceed 30 hours
for all approved E. coli methods.
However, if the State determines on a
case-by-case basis that analyzing an E.
coli sample within 30 hours is not
feasible, the State may approve the
holding of an E. coli sample for up to
48 hours between collection and
initiation of analysis. E. coli samples
held between 30 to 48 hours must be
analyzed by the Colilert reagent version
of Standard Method 9223B as listed in
40 CFR 136.3. All E. coli samples must
be maintained below 10° C and not
allowed to freeze.
The E. coli sample holding time
established for source water monitoring
under the LT2ESWTR does not apply to
E. coli sample holding time
requirements that have been established
under other programs and regulations.
b. Background and Analysis
In the August 11, 2003 proposed
LT2ESWTR, EPA planned to approve
the same E. coli methods that the
Agency had proposed for ambient water
monitoring in an earlier rulemaking,
"Guidelines Establishing Test
Procedures for the Analysis of
Pollutants; Analytical Methods for
Biological Pollutants in Ambient Water"
(USEPA 2001h). EPA selected these
methods based on data generated by
EPA laboratories, submissions to the
EPA alternate test procedures program
and voluntary consensus standards
bodies, peer reviewed journal articles,
and publicly available study reports.
On July 21, 2003, EPA finalized
"Guidelines Establishing Test
Procedures for the Analysis of
Pollutants; Analytical Methods for
Biological Pollutants in Ambient Water"
(USEPA 2003b). The only method from
the proposal of this rule that was not
included in the final rule was Colisure,
which was excluded due to insufficient
data on its performance with surface
water. For the other methods, EPA
revised certain titles and added method
numbers to be consistent with other
microbiological methods, but the
technical content of these methods in
the final rule did not change from the
versions included in the proposed rule.
EPA is approving these same E. coli
methods for analyses under the
LT2ESWTR. The source water E. coli
analyses that PWSs will conduct under
the LT2ESWTR are similar to the
ambient water analyses for which EPA
approved E. coli methods under
"Guidelines Establishing Test
Procedures for the Analysis of
Pollutants; Analytical Methods for
Biological Pollutants in Ambient Water"
(USEPA 2003b). EPA continues to
support the findings of this rule and
believes that the E. coli methods
approved therein have the necessary
sensitivity and specificity to meet the
data quality objectives of the
.LT2ESWTR.
An important aspect of monitoring for
E. coli is the allowable sample holding
time (i.e., the time between sample
collection and initiation of analysis).
Existing regulations, such as 40 CFR
141.74, limit the holding time for E. coli
samples to 8 hours. However, for PWSs
'that must ship E. coli samples to an off-
site laboratory for analysis, meeting an
8 hour holding time is generally not
feasible. For example, during the ICRSS,
all of the PWSs that shipped samples
off-site for E. coli analysis exceeded an
8 hour holding time, and 12 percent of
these samples had holding times in
excess of 30 hours.
While most large PWSs that will
monitor for E. coli under the
LT2ESWTR will conduct these analyses
on-site, most small PWSs must ship
samples off-site to an approved
laboratory. To address the concern that
PWSs using off-site laboratories cannot
meet an 8-hour holding time, EPA
participated in studies to assess the
effect of increased sample holding time
on E. coli analysis results. These studies
are summarized in the proposed rule
(USEPA 2003a) and are described in
detail in Pope et al. (2003). Based on
these studies, EPA has concluded that
the holding time for E. coli samples can
be extended beyond 8 hours prior to
analysis without compromising the data
quality objectives of LT2ESWTR
monitoring.
In the proposed LT2ESWTR, EPA
required analysis of E. coli samples to
be initiated within 24 hours of sample
collection and required that samples be
kept below 10° C and not allowed to
freeze (USEPA 2003a). These proposed
requirements were based on data
showing that most samples maintained
within these temperature conditions
were not significantly different at 24
hours than at the standard holding time
of 8 hours. The proposal also noted that
data indicated no significant sample
degradation after longer time periods,
such as 30 or 48 hours, for certain
methods. Accordingly, EPA requested
comment on establishing a longer E. coli
holding time in the final rule.
For today's final rule, EPA is
establishing a holding time of 30 hours
for all approved E. coli methods. After
reviewing public comment on this issue,
which is summarized in the following
section, and reassessing the studies
described in the proposed rule, EPA has
concluded that a 30 hour holding time
limit for E. coli samples is appropriate
and consistent with the data quality
objectives of LT2ESWTR source water
monitoring. Further, EPA believes that
meeting a 30 hour holding time is
feasible for most PWSs that must ship
E. coli samples to an off-site laboratory
for analysis. This longer holding time,
however, does not apply to E. coli
monitoring conducted under other
programs and regulations.
EPA recognizes that in rare cases,
having an E. coli sample analyzed
within 30 hours may not be feasible for
a PWS due to distance to an approved
laboratory and limited transportation
options. In these cases, today's rule
allows the State to approve up to a 48
hour holding time for E. coli samples.
Samples held between 30 to 48 hours
must be analyzed by the Colilert reagent
version of Standard Method 9223B. This
is the only method evaluated in Pope et
al. (2003) where no significant sample
degradation occurred at 48 hours.
PWSs must maintain samples below
10°C and not allow them to freeze. EPA
has developing guidance for PWSs on
packing and shipping E. coli samples to
maintain these temperature conditions.
See the overview at the beginning of this
section for information on how to access
this guidance.
c. Summary of Major Comments
In the August 11, 2003 LT2ESWTR
proposal, EPA requested comment on
whether the E. coli methods proposed
for approval under the LT2ESWTR are
appropriate and whether there are
additional methods not proposed that
should be considered. EPA also
requested comment on the proposal to
extend the holding time for E. coli
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samples to 24 hours; whether EPA
should limit the extended holding time
to only those E. coli analytical methods
that were evaluated in the holding time
studies described in the proposal; and
whether EPA should increase the source
water E. coli holding time to 30 or 48
hours for samples evaluated by one
method, ONPG-MUG, and retain a 24-
hour holding time for samples analyzed
by other methods.
Most commenters stated that the
proposed E. coli analytical methods are
appropriate. Commenters also agreed
with the proposal to extend the holding
time for source water E. coli samples,
but recommendations about the
maximum holding time and the
methods to which the extended holding
time should apply differed among
commenters. Some suggested that EPA
increase the holding time to 30 hours for
the ONPG-MUG method, but retain a
24-hour holding time for the other
methods. Other commenters
recommended a 48-hour holding time
for some or all methods. Several
commenters advised that holding times
for all methods should be the same to
limit confusion. Some commenters were
concerned that a 30-hour holding time
would not be sufficient for small PWSs
in remote areas to ship samples to
distant laboratories.
After consideration of the comments
received, as well as the holding time
study data presented in the proposed
rule and the time required to ship
samples off-site for analysis as
evidenced in the ICRSS," EPA has
concluded that allowing a 30-hour
holding time for all E. coli methods
approved under today's final rule is
appropriate. Data indicate that a 30-hour
holding time for E. coli samples will not
adversely impact the data quality
objectives of LT2ESWTR monitoring.
Further, establishing the same holding
time for all methods will limit
confusion, and a 30-hour holding time
will allow most PWSs that ship samples
off site for analysis to meet the holding
time requirements. Today's rule also
allows the State to authorize a 48-hour
holding time for rare cases where a 30-
hour holding time is not feasible.
4. Turbidity Methods
a. Today's Rule
Today's rule requires PWSs to use the
analytical methods that have been
previously approved by EPA for
analysis of turbidity in drinking water,
as listed in 40 CFR 141.74. These are
Method 2130B as published in Standard
Methods for the Examination of Water
and Wastewater (APHA 1992), EPA
Method 180.1 (USEPA 1993), Great
Lakes Instruments Method 2 (Great
Lakes Instruments 1992), and Hach
FilterTrak Method 10133.
b. Background and Analysis
As stated in section IV.A, today's rule
requires filtered PWSs serving at least
10,000 people to monitor for turbidity
when they conduct source water
monitoring. EPA may use these data to
modify the indicator criteria that trigger
Cryptosporidium monitoring by small
filtered PWSs, as recommended by the
M-DBP Advisory Committee (USEPA
2000a). In addition, PWSs using
conventional or direct filtration may
achieve additional Cryptosporidium
treatment credit by demonstrating very
low turbidity in the combined filter
effluent, as described in section IV.D.7,
or the individual filter effluent, as
described in section IV.D.8.
The August 11, 2003 proposed
LT2ESWTR required PWSs to use
turbidity methods that EPA had
previously approved under 40 CFR
141.74 for analyzing drinking water
(USEPA 2003a). These are EPA Method
180.1 and Standard Method 2130B,
which are based on a comparison of the
intensity of light scattered by the sample
with the intensity of light scattered by
a standard reference suspension; Great
Lakes Instruments Method 2, which is a
modulated four beam infrared method
using a ratiometric algorithm to
calculate the turbidity value from the
four readings that are produced; and
Hach FilterTrak (Method 10133), which
is a laser-based method used to analyze
finished drinking water.
Today's final rule is unchanged from
the proposal in regard to analytical
methods for turbidity. Hence, PWSs
must use methods currently approved in
40 CFR 141.74 for turbidity analysis.
EPA believes the currently approved
methods are appropriate for turbidity
analvses that will be conducted under
the LT2ESWTR. PWSs must use
turbidimeter instruments as described
in the EPA-approved methods, which
may be either on-line or bench top
instruments. If a PWS chooses to use on-
line instruments for monitoring
turbidity, the PWS must validate the
continuous measurements for accuracy
on a regular basis using a protocol
approved by the State, as required in 40
CFR 141.74.
c. Summary of Major Comments
EPA received public comment on the
turbidity methods required in the
August 11, 2003 proposed LT2ESWTR.
While commenters, in general, agreed
that currently approved turbidity
methods are adequate to meet the
requirements of the rule, several
commenters were concerned with
turbidity measurement variation among
different instruments. One commenter
suggested voluntary third party testing,
while another recommended more
rigorous calibration and verification
processes.
As described in section IV.D.7, EPA
has reviewed studies of low level
turbidity measurements, as well as
standard test methods for measurement
of turbidity below 5 NTU. Alter
reviewing this information, EPA
concluded that currently available
monitoring equipment can reliably
measure turbidity at levels of 0.15 NTU
and lower. However, EPA agrees that
rigorous calibration and maintenance of
turbidity monitoring equipment is
necessary for PWSs pursuing the low
filtered water turbidity performance
options in the microbial toolbox. EPA
has developed guidance on proper
calibration, operation, and maintenance
of turbidimeters (USEPA 1999c).
A few commenters stated that the
LT2ESTWR does not recognize
advancements in turbidity measurement
and newly developed turbidity
measurement technologies. In response,
EPA has not received information that
supports approval of analytical methods
for turbidity in addition to those
currently approved under 40 CFR
141.74, which are also approved for
turbidity monitoring under today's rule.
If other turbidity methods are approved
and added to 40 CFR 141.74 in the
future, these methods will also be
approved under the LT2ESWTR.
One commenter requested that the
LT2ESWTR specifically address
turbidity measurements in plants that
practice lime softening. EPA notes that
additional treatment credit for
combined filter effluent turbidity is
based on measurements collected under
40 CFR 141.173 or 40 CFR 141.551 (the
IESWTR or LTlESWTR). These
regulations allow PWSs that use lime
softening to acidify samples prior to
analysis in order to address the efiects
of lime softening on turbidity
measurements. In regard to treatment
credit based on individual filter effluent
turbidity, EPA does not believe that
acidifying samples while measuring
turbidity every 15 minutes at each
individual filter, as the IESWTR and
LTlESWTR require, is feasible.
However, PWSs that practice lime
softening could use the demonstration
of performance toolbox option to
demonstrate that a plant is achieving
removal efficiencies equivalent to the
additional credit allowed for individual
filter performance.
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727
K. Laboratory Approval
Given the potentially significant
implications for PWSs and drinking
water consumers of microbial
monitoring under the LT2ESWTR,
laboratory analyses for
Cryptosporidium, E. coli, and turbidity
should be accurate and reliable within
the limits of approved methods.
Therefore, today's final rule requires
PWSs to use laboratories that have been
approved to conduct analyses for these
parameters by EPA or the State.
1. Cryptosporidium Laboratory
Approval
a. Today's Rule
Analysis of samples for
Cryptosporidium under today's rule
must be conducted by a laboratory that
is approved under EPA's Laboratory
Quality Assurance Evaluation Program
(Lab QA Program) for Analysis of
Cryptosporidium in Water (described in
67 FR 9731, March 4, 2002, USEPA
2002d). A list of laboratories that are
approved under this program is
available on the Internet at
www.epa.gov/safewatsr/disinfection/lt2.
If a State adopts an equivalent approval
process under a State laboratory
certification program, then PWSs can
use laboratories approved by the State.
b. Background and Analysis
Because States do not currently
approve laboratories for
Cryptosporidium analyses, EPA has
assumed initial responsibility for
Cryptosporidium laboratory approval.
EPA initiated the Cryptosporidium Lab
QA Program prior to LT2ESWTR
promulgation to ensure that adequate
analytical capacity will be available at
approved laboratories to support
required monitoring, which begins 6
months after rule promulgation. The
August 11, 2003 proposed LT2ESWTR
required PWSs to have Cryptosporidium
samples analyzed by laboratories
approved under the EPA Lab QA
Program. Today's final rule is
unchanged from the proposal with
respect to this requirement.
Laboratories seeking approval under
the EPA Lab QA Program for
Cryptosporidium analysis must submit
an interest application to EPA,
successfully analyze a set of initial
performance testing samples, and
undergo an on-site evaluation.
Laboratories that pass the quality
assurance evaluation are approved for
Cryptosporidium analysis under the
LT2ESWTR. To maintain approval,
laboratories must successfully analyze a
set of three ongoing proficiency testing
samples approximately every four
months. The Lab QA Program is
described in detail in USEPA (2002d)
and additional information can be found
on the Internet at www.epa.gov/
safewater/disinfection/lt2.
EPA tracks the Cryptosporidium
sample analysis capacity of approved
laboratories through the Lab QA
Program. Using information provided by
laboratories, EPA expects that existing
capacity should be sufficient to support
initial source water monitoring bv large
PWSs under the LT2ESWTR. Further,
the implementation schedule for today's
rule, which is described in section IV.G,
provides time for laboratories to
increase capacity through steps like
training new analysts as the demand for
sample analysis grows.
c. Summary of Major Comments
In regard to approval of laboratories
for Cryptosporidium analysis, major
comments on the August 11, 2003
proposal addressed the following issues:
laboratory capacity, State approval
programs, and analyst experience
criteria. Comments regarding
Cryptosporidium laboratory capacity are
summarized in section IV.G, while those
on the other issues are summarized as
follows.
EPA requested comment on States
approving Cryptosporidium
laboratories. Most commenters,
however, recommended that EPA
maintain the Lab QA Program, due to
the specialized nature of the work. EPA
intends to maintain the Lab QA
Program, but today's rule does allow
States to certify Cryptosporidium
laboratories by setting up an equivalent
program.
EPA also requested comment on the
experience criteria that Methods 1622
and 1623 include for Cryptosporidium
analysts. Some commenters
recommended lowering analyst training
and experience requirements, while
others recommended no change or an
increase in microscopy training. After
evaluating these comments, EPA has
concluded that the analyst criteria
included in Methods 1622 and 1623 are
reasonable for ensuring that analysts
have the experience to evaluate source
water samples under today's rule.
Consequently, EPA has not altered these
criteria from the approved methods.
2. E. coli Laboratory Approval
a. Today's Rule
PWSs must have E. coli samples
analyzed by a laboratory that has been
certified by EPA, the National
Environmental Laboratory Accreditation
Conference (NELAC) or the State for
total coliform or fecal coliform analysis
in drinking water under 40 CFR 141.74.
The laboratory must use the same
technique for E. coli analysis under
today's rule that the laboratory is
certified to use for drinking water under
40 CFR 141.74 (e.g., membrane
filtration, multiple-well, multiple-tube).
b. Background and Analysis
The August 11, 2003 proposed
LT2ESWTR required PWSs to have E.
coli samples analyzed by laboratories
that are certified to conduct total or
fecal coliform analyses in drinking
water (i.e., under 40 CFR 141.74) by
EPA, NELAC or the State. The proposal
required laboratories to use the same E.
coli analytical technique that they are
certified to use for coliform analyses in
drinking water. Today's final rule is
unchanged from the proposal in regard
to these requirements. EPA believes that
laboratories that are certified to conduct
coliform analyses in drinking water
have the expertise to conduct E. coli
analyses under today's rule, provided
they use the analytical technique for
which they are certified.
c. Summary of Major Comments
Two commenters on the August 11,
2003 proposal suggested that
laboratories should be certified
specifically for quantitative analyses of
total or fecal coliform in a source water
matrix. However, the methods approved
for source water E. coli analyses under
today's rule are also approved under the
drinking water certification program.
EPA believes that analysts certified for
these methods under the drinking water
certification program have the capability
to perform the same methods for a
source water matrix, even though
additional steps may be required (such
as dilutions). EPA has revised the
Laboratory Certification Manual to
suggest Performance Evaluation (PE)
samples for source water matrix
analyses and States have the option to
require PE samples as needed in their
State laboratory certification programs.
3. Turbidity Analyst Approval
a. Today's Rule
Under today's rule, measurements of
turbidity must be made by a party
approved by the State.
b. Background and Analysis
The August 11, 2003 proposed
LT2ESWTR required that measurements
of turbidity be made by a party
approved by the State. This reflects
existing requirements in 40 CFR 141.74
for measurement of turbidity in drinking
water. Today's final rule is unchanged
from the proposal in this respect.
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c. Summary of Major Comments
Commenters on requirements for
turbidity analyst approval in the August
11, 2003 proposal agreed that turbidity
analyses should be consistent with 40
CFR 141.74. Specifically, any person
that is currently approved to conduct
turbidity analysis under existing
drinking water regulations should be
approved to conduct turbidity analyses
under the LT2ESWTR. EPA agrees with
this comment and it is reflected in
today's final rule.
L. Requirements for Sanitary Surveys
Conducted by EPA
1. Today's Rule
Today's final rule establishes
requirements for PWSs to respond to
significant deficiencies identified in
sanitary surveys that EPA conducts.
These requirements give EPA authority
equivalent to that exercised by States
under existing regulations to ensure that
PWSs address significant deficiencies.
• For sanitary surveys conducted by
EPA under SDWA section 1445 or other
authority, PWSs must respond in
writing to significant deficiencies
outlined in sanitary survey reports no
later than 45 days after receipt of the
report, indicating how and on what
schedule the PWS will address
significant deficiencies noted in the
survey.
• PWSs must correct significant
deficiencies identified in sanitary
survey reports according to the schedule,
approved by EPA, or if there is no
approved schedule, according to the
schedule the PWS reported if such
deficiencies are within the control of the
PWS.
• A sanitary survey, as conducted by
EPA, is an onsite review of the water
source (identifying sources of
contamination by using results of source
water assessments where available),
facilities, equipment, operation,
maintenance, and monitoring
compliance of a PWS to evaluate the
adequacy of the PWS, its sources and
operations, and the distribution of safe
drinking water. A significant deficiency
includes a defect in design, operation,
or maintenance, or a failure or
malfunction of the sources, treatment,
storage, or distribution system that EPA
determines to be causing, or has the
potential for causing the introduction of
contamination into the water delivered
to consumers.
2. Background and Analysis
As established by the IESWTR in 40
CFR 142.16(b)(3), primacy States must
conduct sanitary surveys for PWSs
using surface water sources every three
or five years. The sanitary survey is an
onsite review of the following: (1)
Source, (2) treatment, (3) distribution
system, [4) finished water storage, (5)
pumps, pump facilities, and controls,
(6) monitoring, reporting, and data
verification, (7) system management and
operation, and (8) operator compliance
with State requirements.
Under the IESWTR, primacy States
must have the authority to assure that
PWSs respond in writing to significant
deficiencies identified in sanitary
survey reports no later than 45 days
after receipt of the report, indicating
how and on what schedule the system
will address the deficiency (40 CFR
142.16(b)(l)(ii)). Further, primacy States
must have the authority to assure that
systems take necessary steps to address
significant deficiencies identified in
sanitary survey reports if such
deficiencies are within the control of the
system and its governing body (40 CFR
EPA conducts sanitary surveys under
SDWA section 1445 for PWSs not
regulated by primacy States (e.g.. Tribal
systems, Wyoming). However, the
authority required of primacy States
under 40 CFR 142 to ensure that PWSs
address significant deficiencies
identified during sanitary surveys does
not extend to EPA. Consequently, the
sanitary survey requirements
established by the IESWTR created an
unequal standard. PWSs regulated by
primacy States are subject to the States'
authority to require correction of
significant deficiencies noted in sanitary
survey reports, while PWSs for which
EPA has direct implementation
authority did not have to meet an
equivalent requirement.
In the August 11, 2003 proposal, EPA
requested comment on establishing
requirements under 40 CFR 141 for
PWSs to correct significant deficiencies
identified in sanitary surveys conducted
by EPA. The requirements in today's
final rule follow closely on the language
presented in the proposal. Today's rule
ensures that PWSs in non-primacy
States are subject to comparable
requirements for sanitary surveys as
PWS regulated by States with primacy.
3. Summary of Major Comments
Most public comment on the August
11, 2003 proposal supported requiring
PWSs to correct significant deficiencies
identified in sanitary surveys conducted
by EPA. Commenters stated that
requirements for sanitary surveys
should be consistent for PWSs and
should not depend on the primacy
agency. EPA believes the requirements
in today's final rule will establish this
consistency.
One commenter requested that EPA
include a process for PWSs to appeal a
significant deficiency determination.
EPA expects that PWSs will raise any
concerns regarding significant
deficiency'determinations with the
primacy agency, either the State or EPA,
that conducts the sanitary survey. States
or EPA may withdraw or amend their
significant deficiency determinations as
appropriate. The IESWTR did not
establish a separate appeal process for
sanitary surveys conducted by States,
and EPA has not established such a
process for sanitary surveys conducted
by EPA under today's rule.
M. Variances and Exemptions
SDWA section 1415 allows States to
grant variances from national primary
drinking water regulations under certain
conditions; section 1416 establishes the
conditions under which States may
grant exemptions to MCL or treatment
technique requirements. These
conditions and EPA's view on their
applicability to the LT2ESWTR are
summarized as follows:
1. Variances
Section 1415 specifies two provisions
under which general variances to
treatment technique requirements may
be granted:
(1) A State that has primacy ma\ grant a
variance to a PWS from any requirement to
use a specified treatment technique for a
contaminant if the PWS demonstrates to the
satisfaction of the State that the treatment
technique is not necessary to protect public
health because of the nature of the PVVS's raw
water source. EPA may prescribe monitoring
and other requirements as conditions ol the
variance (section 1415(a)(l)(B)).
(2) EPA may grant a variance from any
treatment technique requirement upon a
showing by any person that an alternative
treatment technique not included in such
requirement is at least as efficient in lowering
the level of the contaminant (section
1415(a)(3))
EPA does not believe that the first
variance provision is applicable to
filtered PWSs under today's rule.
Filtered PWSs are required to
implement additional treatment under
the LT2ESWTR only when source water
monitoring demonstrates higher levels
of Cryptosporidium contamination.
Thus, this treatment technique
requirement accounts for the nature of
the PWS's raw water source. Unfiltered
PWS treatment requirements also
account for the nature of a PWS's raw
water source with respect to whether 2-
or 3-log Cryptosporidium inactivation is
required.
In theory, the first variance provision
could be applied to the requirement that
all unfiltered PWSs provide at least 2-
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729
log Cryptosporidium inactivation. If an
unfiltered PWS could show a raw water
Cryptosporidium level 3-log lower than
the Bin 1 cutoff for filtered PWSs (i.e.,
below 0.075 oocysts/1,000 L), this could
demonstrate that no treatment for
Cryptosporidium is necessary. The
unfiltered PWS would already be
achieving public health protection
against Cryptosporidium equivalent to
filtered PWSs due to the nature of the
raw water source.
In practice, EPA has not identified an
approach that is economically or
technologically feasible for a PWS to
demonstrate such a low level of
Cryptosporidium to support granting a
variance. This is due to the extremely
large volume and number of samples
that would be necessary to make such
a demonstration with confidence.
'However, unfiltered PWSs may choose
to pursue the development and
implementation of monitoring programs
to apply for a variance from
Cryptosporidium inactivation
requirements based on the nature of the
raw water source. A sufficient
monitoring program may be feasible in
site-specific circumstances or with the
use of innovative approaches.
The second provision for granting a
variance is not applicable to the
LT2ESWTR because the rule provides
broad flexibility in how PWSs achieve
the required level of Cryptosporidium
reduction through the microbial
toolbox. Moreover, the microbial
toolbox contains an option for
Demonstration of Performance, under
which States can award treatment credit
based on the demonstrated efficiency of
a treatment process in reducing
Cryptosporidium levels. Thus, there is
no need for this type of variance under
the LT2ESWTR. "
SDWA section 1415(e) describes small
PWS variances, but these cannot be
granted for a treatment technique for a
microbial contaminant. Hence, small
PWS variances are not allowed for the
LT2ESWTR.
2. Exemptions
Under SDWA section 1416(a), a State
may exempt any PWS from a treatment
technique requirement upon a finding
that (1) Due to compelling factors
(which may include economic factors
such as qualification of the PWS as
serving a disadvantaged community),
the PWS is unable to comply with the
requirement or implement measures to
develop an alternative source of water
supply; (2) the PWS was in operation on
the effective date of the treatment
technique requirement, or for a PWS
that was not in operation by that date,
no reasonable alternative source of
drinking water is available to the new
PWS; (3) the exemption will not result
in an unreasonable risk to health; and
(4) management or restructuring
changes (or both) cannot reasonably
result in compliance with the Act or
improve the quality of drinking water.
EPA believes that granting an
exemption to the Cryptosporidium
treatment requirements of the
LT2ESWTR would result in an
unreasonable risk to health. As
described in section III.C,
Cryptosporidium causes acute health
effects, which may be severe in sensitive
subpopulations and include risk of
mortality. Moreover, the additional
Cryptosporidium treatment
requirements of the LT2ESWTR are
targeted to PWSs with the highest
degree of risk. Due to these factors, EPA
does not support the granting
exemptions from the LT2ESWTR.
V. State Implementation
A. Today's Rule
This section describes the regulations
and other procedures and policies States
must adopt to implement today's rule.
States must continue to meet all other
conditions of primacy in 40 CFR Part
142. To implement the LT2ESWTR,
States must adopt revisions to the
following sections:
§ 141.2—Definitions
Subpart Q—Public Notification
New Subpart W—Additional treatment
technique requirements for
Cryptosporidium
§ 142.14—Records kept by States
§ 142.15—Reports by States
§142.16—Special primacy requirements
1. Special State primacy requirements
To ensure that a State program
includes all the elements necessary for
an effective and enforceable program
under today's rule, a State primacy
application must include a description
of how the State will perform the
following:
• Approve an alternative to the E. coli
levels that trigger Cryptosporidium
monitoring by filtered systems serving
fewer than 10,000 people (see section
IV.A.l);
• Approve watershed control
programs for the 0.5 log watershed
control program credit in the microbial
toolbox (see section IV.D.2);
• Assess significant changes in the
watershed and source water as part of
the sanitary survey process and
determine appropriate follow-up action
(see section IV.A); and
• Approve protocols for treatment
credit under the Demonstration of
Performance toolbox option (see section
IV.D.9), for site specific chlorine dioxide
and ozone CT tables (see section
IV.D.14), and for alternative UV reactor
validation testing (see section IV.D.15).
A State program can be more, but not
less, stringent than Federal regulations.
As such, some of the elements listed
here may not be applicable to a specific
State program.
2. State Recordkeeping Requirements
Today's rule requires States to keep
additional records of the following,
including all supporting information
and an explanation of the. technical
basis for each decision:
• Results of source water E. coli and
Cryptosporidium monitoring for not less
than 1 year;
• Cryptosporidium treatment bin
classification for each filtered PWS after
the initial and after the second round of
source water monitoring. Also, any
change in treatment requirements for
filtered systems due to watershed
assessment during sanitary surveys;
• Determination of whether each
unfiltered PWS has a mean source water
Cryptosporidium level above 0.01
oocysts/L after the initial and after the
second round of source water
monitoring;
• The treatment processes or control
measures that each PWS employs to
meet Cryptosporidium treatment
requirements under the LT2ESWTR,
including measures that systems may
use for only part of the year; and
• A list of PWSs required to cover or
treat the effluent of an uncovered
finished water storage facilities.
3. State Reporting Requirements
Today's rule requires States to report
the following information:
• The Cryptosporidium treatment bin
classification for each filtered PWS after
the initial and after the second round of
source water monitoring. Also, any
change in treatment requirements for
filtered systems due to watershed
assessment during sanitary surveys; and
• The determination of whether each
unfiltered PWS has a mean source water
Cryptosporidium level above 0.01
oocysts/L after the initial and after the
second round of source water
monitoring.
4. Interim Primacy
States that have primacy (including
interim 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 USEPA, or
the effective date of its revised
regulations, whichever is later. A State
that wishes to obtain interim primacy
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for future NPDWRs must obtain primacy
for today's rule. As described in Section
IV.A, EPA expects to work with States
to oversee the initial source water
monitoring that begins six months
following rule promulgation.
B. Background and Analysis
SDWA establishes requirements that a
State or eligible Indian Tribe must meet
to assume and maintain primary
enforcement responsibility (primacy) for
its PWSs. These requirements include
the following activities: (I) 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
SDWA; and (5) adopting and being
capable of implementing an adequate
plan for the provisions of safe drinking
water under emergency situations.
40 CFR part 142 sets out the specific
program implementation requirements
for States to obtain primacy for the
public water supply supervision
program as authorized under SDWA
section 1413. In addition to adopting
basic primacy requirements specified in
40 CFR Part 142, States may be required
to adopt special primacy provisions
pertaining to specific regulations where
implementation of the rule involves
activities beyond general primacy
provisions. States must include these
regulation specific provisions in an
application for approval of their
program revision.
The current regulations in 40 CFR
142.14 require States with primacy to
keep various records, including the
following: analytical results to
determine compliance with MCLs,
MRDLs, and treatment technique
requirements; PWS inventories; State
approvals; enforcement actions; and the
issuance of variances and exemptions.
Today's final rule requires States to
keep additional records, including all
supporting information and an
explanation of the technical basis for
decisions made by the State regarding
today's rule requirements. EPA
currently requires in 40 CFR 142.15 that
States report to EPA information such as
violations, variance and exemption
status, and enforcement actions, and
today's rule adds additional reporting
requirements related to monitoring and
treatment requirements.
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, April 28, 1998) (USEPA
1998c). 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 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
(including interim primacy) for every
existing NPDWR in effect when the new
regulation is promulgated. States that
have primacy for every existing NPDWR
already in effect may obtain interim
primacy for this rule and a State that
wishes to obtain interim primacy for
future NPDWRs must obtain primacy for
this rule.
C. Summary of Major Comments
Public comment generally supported
the special primacy requirements in the
August 11, 2003 proposal, and many
commenters expressed appreciation for
the flexibility the special primacy
requirements provided to States. One
commenter expressed concern that a
State that adopted this rule by reference
would lose the flexibility intended in
the proposal. In response, EPA
recognizes that some States may be
limited by their statutes in applying the
flexibility allowed under today's rule.
However. EPA believes that providing
flexibility for States to approve site-
specific approaches that achieve the
public health goals of the LT2ESWTR is
appropriate and will benefit some States
and PWSs.
A few commenters were concerned
that the special primacy requirement to
assess changes in watersheds as part of
the sanitary survey process would be
difficult to meet due to a lack of
resources or large watersheds that
overlap State boundaries. In response,
EPA notes that States are required to
evaluate PWS sources under the existing
sanitary survey requirements (40 CFR
142.16(b)(3}). if a State determines
during a sanitary survey that significant
changes have occurred in the watershed
that could lead to increased
contamination of the source by
Cryptosporidium, today's rule gives the
State the authority to require the PWS
to take actions to mitigate or treat the
contamination. Because the treatment
requirements in today's rule depend on
the degree of source water
contamination, EPA believes that this
assessment of changes in a PWS's
source water following initial bin
classification is necessary.
EPA also received comments on State
approval processes for laboratories
analyzing for Cryptosporidium to meet
LT2ESWTR requirements. Most
commenters stated that EPA should
maintain a national certification
program for laboratories approved for
Cryptosporidium analysis for
LT2ESTWR compliance. Commenters
indicated that requiring States to
approve laboratories for
Cryptosporidium analysis placed too
great a demand on State resources.
Today's rule does not include a State
primacy requirement for laboratory
certification for Cryptosporidium
analysis.
Some commenters were concerned
with the data tracking and review
burden on States from the reporting
requirements for the individual toolbox
components. EPA agrees with
commenters that, in some cases.
allowing PWSs to report summaries or
to self-certify that the PWS met the
performance requirements for microbial
toolbox treatment credit may be
appropriate. Today's rule allow States to
modify the level of reporting required
for toolbox components and
specifically, permit PWSs to self-certify
to the State that a toolbox component
has met its performance requirements.
VI. Economic Analysis
This section summarizes the
economic analysis (EA) for the final
LT2ESWTR. The EA is an assessment of
the benefits, both health and nonhealth-
related, and costs to the regulated
community of the final regulation, along
with those of regulatory alternatives that
the Agency considered. EPA developed
the EA to meet the requirement of
SDWA section 1412(b)(3)(C) for a Health
Risk Reduction and Cost Analysis
(HRRCA), as well as the requirements of
Executive Order 12866, Regulatory
Planning and Review, under which EPA
must estimate the costs and benefits of
the LT2ESWTR. The full EA is
presented in Economic Analysis for the
Long Term 2 Enhanced Surface Water
Treatment Rule (USEPA 2005a), which
includes additional details and
discussion on the topics presented
throughout this section of the preamble.
The LT2ESWTR is the second in a
staged set of rules that address public
health risks from microbial
contamination of surface and GWUDI
drinking water supplies and, more
specifically, prevent Cryptosporidium
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731
from reaching consumers. As described
in section III, EPA promulgated the
IESWTR and LTlESWTR to provide a
baseline of protection against
Cryptosporidium in large and small
PWSs, respectively. Today's final rule
will achieve further reductions in
Cryptosporidium exposure for PWSs
with the highest vulnerability. This EA
considers only the incremental
reduction in exposure beyond the two
previously promulgated rules (IESWTR
and LTlESWTR) from the alternatives
evaluated for the LT2ESWTR.
A. What Regulatory Alternatives Did the
Agency Consider?
Regulatory alternatives considered by
the Agency for the LT2ESWTR were
developed through the deliberations of
the Stage 2 M-DBP Federal Advisory
Committee (described in section III).
The Advisory Committee considered
several general approaches for reducing
the risk from Cryptosporidium in
drinking water. These approaches
included both additional treatment
requirements for all PWSs and risk-
targeted treatment requirements for
PWSs with the highest vulnerability to
Cryptosporidium following
implementation of the IESWTR and
LTlESWTR. In addition, the Advisory
Committee considered related issues
such as alternative monitoring
strategies.
After considering these general
approaches, the Advisory Committee
focused on four regulatory alternatives
for filtered PWSs (see Table VI.A-1).
With the exception of Alternative 1,
which requires all PWSs to provide
additional treatment for
Cryptosporidium, these alternatives
incorporate a risk-targeting approach in
which PWSs are classified in different
treatment bins based on the results of
source water monitoring. Additional
Cryptosporidium treatment
requirements are directly linked to the
treatment bin classification.
Accordingly, these rule alternatives are
differentiated by two criteria: (l) The
Cryptosporidium concentrations that
define the bin boundaries and (2) the
degree of treatment required for each
bin.
The Advisory Committee reached
consensus regarding additional
treatment requirements for unfiltered
PWSs without formally identifying
regulatory alternatives other than
requiring no treatment for
Cryptosporidium (i.e., no new
regulation).
TABLE VI.A-1.—SUMMARY OF REGU-
LATORY ALTERNATIVES FOR FIL-
TERED PWSs
Mean source water
Cryptosporidium moni-
toring result (oocysts/L)
Additional treatment
requirements1
Alternative A1
2.0-log inactivation required for all PWSs
Alternative A2
<0.03
> 0.03 and < 0.1
>0.1 and < 1.0 .
> 1.0
No additional treat-
ment
0.5-log
1.5-log
2.5-log.
Alternative A3—Today's Final Rule
0.075
> 0.075 and < 1.0
> 1.0 and < 3.0 ....
>3.0
No additional treat-
ment
1-log
2-log.
2.5-log
Alternative A4
< 0.1
> 0.1 and < 1.0
No additional treat-
ment.
0 5-log
1.0-log.
1 Note. "Additional treatment requirements"
are in addition to levels already required under
existing rules (e.g, the IESWTR and
LT1ESWTR) for PWSs using conventional
treatment or equivalent
B. What Analyses Support Today's Final
Rule?
EPA has quantified benefits and costs
for each of the filtered PWS regulatory
alternatives in Table VI.A-1 and for
unfiltered PWS requirements.
Quantified benefits stem from estimated
reductions in the incidence of
cryptosporidiosis resulting from the
regulation. To make these estimates, the
Agency employed Monte Carlo
modeling to account for uncertainty and
variability in key parameters like
Cryptosporidium occurrence,
infectivity, and treatment efficiency.
Costs result largely from the installation
of additional treatment, with lesser costs
due to monitoring and other
implementation activities.
Cryptosporidium occurrence
significantly influences the estimated
benefits and costs of regulatory
alternatives. As discussed in section
III.E, EPA analyzed data collected under
the ICR, the ICR Supplemental Surveys
of medium PWSs (ICRSSM), and the ICR
Supplemental Surveys of large PWSs
(ICRSSL) to estimate"the national
occurrence distribution of
Cryptosporidium in surface water. EPA
evaluated these distributions
independently when assessing benefits
and costs for different regulatory
alternatives.
Another parameter that significantly
influences estimated benefits is
Cryptosporidium infectivity (i.e., the
likelihood of infection after exposure to
a given dose of Cryptosporidium). As
discussed in section III.E, EPA
considered results from human
volunteer feeding studies and applied
six different model forms to estimate
dose-response relationships.
To address uncertainty in these
estimates, benefits are presented for
three different dose response models: A
"high" estimate based on the model that
showed the highest mean baseline risk,
a "medium" estimate based on the
model and data used at proposal, which
is in the middle of the range of estimates
produced by the six models, and a
"low" estimate, based on the model that
showed the lowest mean baseline risk.
These estimates are not upper and lower
bounds. For each model, a distribution
of effects is estimated, and the "high"
and "low" estimates show only the
means of these distributions for two
different model choices.
Both benefits and costs are
determined as-annualized present
values, which allows comparison of cost
and benefit streams that are variable
over time. The time frame used for both
benefit and cost comparisons is 25
years. The Agency uses social discount
rates of both 3 percent and 7 percent to
calculate present values from the stream
of benefits and costs and also to
annualize the present value estimates
over 25 years (see EPA's Guidelines for
Preparing Economic Analyses (USEPA
2000c) for a discussion of social
discount rates).
Results of these analyses are
summarized in this section of the
preamble. Detailed results and
descriptions of the supporting analyzes
are shown in the LT2ESWTR EA
(USEPA 2005a).
In evaluating the regulatory
alternatives shown in Table VI.A—1,
EPA and the Advisory Committee were
concerned with the following questions:
(1) Do the treatment requirements
adequately control Cryptosporidium
.concentrations in finished water? (2)
How many PWSs will be required to
add treatment? and (3) What is the
likelihood that PWSs will be
misclassified in higher or lower
treatment bins through monitoring?
Consistent with the consensus
recommendation of the Advisory
Committee, EPA selected Alternative A3
for today's final rule. EPA has
determined that this alternative will
significantly reduce the incidence of
cryptosporidiosis due to drinking water
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in vulnerable PWSs and is feasible for
PWSs to implement.
Alternative Al (across-the-board 2-log
inactivation) was not selected because it
would impose costs but provide few
benefits to PWSs with relatively low
Cryptosporidium risk. EPA was also
concerned about the feasibility of
requiring every surface water treatment
plant to install additional treatment
processes (e.g., UV) for
Cryptosporidium. With Alternative A2,
EPA was concerned with the feasibility
of accurately classifying PWSs in
treatment bins at a Cryptosporidium
concentration of 0.03 oocysts/L. EPA
does not believe that Alternative A4
would reduce risks from
Cryptosporidium in vulnerable PWSs to
the extent feasible, as required under
SDWA section 1412(b)(7)(A), because of
the low levels of treatment required.
C. What Are the Benefits of the
LT2ESWTR?
EPA has quantified and monetized
health benefits for reductions in
endemic cryptosporidiosis due to the
LT2ESWTR. In addition, today's rule is
expected to provide additional health
and nonhealth-related benefits that EPA
was unable to quantify. Table VI.C—1
summarizes these unquantified benefits.
I. Nonquantified Benefits
TABLE VI.C-1.—SUMMARY OF NONQUANTIFIED BENEFITS
Benefit type
Potential effect on
benefits
Comments
Reducing outbreak risks and response
costs.
Reducing averting behavior (e.g.. boil-
ing tap water or purchasing bottled
water).
Improving aesthetic water quality
Reducing risk from co-occurring and
emerging pathogens.
Increased source water monitoring
Reduced contamination due to cov-
ering or treating finished water stor-
age facilities.
Change in the levels of disinfection by-
products
Increase
Increase/No Change
Increase
Increase
Increase
Increase . ..
Increase/Decrease
Some human or equipment failures may occur even with the requirements of
today's rule; however, by adding barriers of protection for some PWSs, the
rule will reduce the possibility of such failures leading to outbreaks.
Consumers in PWSs that cease using uncovered finished water reservoirs
(through covering or taking such reservoirs off-line) may have greater con-
fidence in water quality This may result in less averting behavior that re-
duces both out-of-pocket costs (e g., purchase of bottled water) and oppor-
tunity costs (e.g., time to boil water)
Some technologies installed for this rule (e.g , ozone) are likely to reduce
taste and odor problems
Although focused on removal of Cryptosporidium from drinking water, PWSs
that change treatment processes will also increase removal of pathogens
that the rule does not specifically regulate.
The greater understanding of source water quality that results from monitoring
may enhance the ability of plants to optimize treatment operations in ways
other than those addressed in this rule.
Contaminants introduced through uncovered finished water storage facilities
will be reduced, which will produce positive public health benefits.
PWSs that install ozone to comply with the LT2ESWTR may experience an in-
crease in certain DBPs PWSs that install UV or microfiltration may reduce
the use of chlorine and experience a decrease in DBPs.
Source. Chapter 5 of the LT2ESWTR Economic Analysis (USEPA 2005a)
2. Quantified Benefits
In quantifying benefits for the
LT2ESWTR based on reductions in the
risk of endemic cryptosporidiosis, EPA
considered several categories of
monetized benefits. First, EPA estimated
the number of cases expected to result
in premature mortality (primarily for
members of sensitive subpopulations
such as AIDS patients). The mortality
estimate was developed using data from
the Milwaukee cryptosporidiosis
outbreak of 1993 (described in section
III), with adjustments to account for the
subsequent decrease in the mortality
rate among people with AIDS and for
the difference between the portion of
people living with AIDS in 1993 in
Milwaukee and the current and
projected national levels. EPA estimated
a mortality rate of 26.3 deaths per
100,000 illnesses for those served by
unfiltered PWSs and a mortality rate of
16.7 deaths per 100,000 illnesses for
those served by filtered PWSs. These
different rates are associated with the
incidence of AIDS in populations served
by unfiltered and filtered PWSs. A
complete discussion on how EPA
derived these rates can be found in
subchapter 5.2 of the LT2ESWTR EA
(USEPA 2005a).
Reductions in mortalities were
monetized using EPA's standard
methodology for monetizing mortality
risk reduction. This methodology is
based on a distribution of value of
statistical life (VSL) estimates from 26
labor market and stated preference
studies. The mean VSL is $7.4 million
in 2005 with a 5th to 95th percentile
range of $1.2 to $16.9 million. A more
detailed discussion of these studies and
the VSL estimate can be found in EPA's
Guidelines for Preparing Economic
Analyses (USEPA 2000c). A real income
growth factor was applied to these
estimates of approximately 1.9 percent
per year for the 20-year time span
following implementation. Income
elasticity for VSL was estimated as a
triangular distribution that ranged from
0.08 to 1.00, with a mode of 0.40. VSL
values for the 20-year span are shown in
the LT2ESWTR EA in Exhibit 5.24
(USEPA 2005a).
The substantial majority of cases are
not expected to be fatal and the Agency
separately estimated the value of non-
fatal illnesses avoided that would result
from the LT2ESWTR. For these, EPA
first divided projected cases into three
categories, mild, moderate, and severe.
and then calculated a monetized value
per case avoided for each severity level.
These were then combined into a
weighted average value per case based
on the relative frequency of each
severity level. According to a study
conducted by Corso et al. (2003), the
majority of illness fall into the mild
category (88 percent). Approximately 11
percent of illness fall into the moderate
category, which is defined as those who
seek medical treatment but are not
hospitalized. The final 1 percent have
severe symptoms that result in
hospitalization. EPA estimated different
medical expenses and time losses for
each category.
Benefits for non-fatal cases were
calculated using a cost-of-illness (COI)
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733
approach. Traditional COI valuations
focus on medical costs and lost wages,
and leave out significant categories of
benefits, specifically the reduced utility
from being sick (i.e., lost personal or
non-work time, including activities such
as child care, homemaking, community
service, time spent with family,
recreation, and pain and suffering),
although some COI studies also include
an estimate for unpaid labor (household
production) valued at an estimated wage
rate designed to reflect the market value
of such labor (e.g., median wage for
household domestic labor). Ideally, a
comprehensive willingness to pay
(WTP) estimate would be used that
includes all categories of loss in a single
number. However, a review of the
literature indicated that the available
studies were not suitable for valuing
cryptosporidiosis; hence, estimates from
this literature are inappropriate for use
in this analysis. Instead, EPA presents
two COI estimates: A traditional
approach that only includes valuation
for medical costs and lost work time
(including some portion of unpaid
household production); and an
enhanced approach that also factors in
valuations for lost unpaid work time for
employed people, reduced utility (or
sense of well-being) associated with
decreased enjoyment of time spent in
non-work activities, and lost
productivity at work on days when paid
workers are ill but go to work anyway.
Table VI.C-2 shows the various
categories of loss and how they were
valued for each estimate for a "typical"
case in 2003 (weighted average based on
severity level).
TABLE VI.C-2.—TRADITIONAL AND ENHANCED COI FOR CRYPTOSPORIDIOSIS, 2003$
[Weighted average cost per case]
Loss category
Direct Medical Costs
Lost Paid Work Days
Lost Unpaid Work Days 1
Lost Leisure Time2 .... .. ..
Lost Caregiver Days3
Lost Leisure Productivity4
Lost Productivity at Work
Total
Traditional
COI
$10691
120 13
24 32
not included
22 98
not included
not included
274.34
Enhanced COI
10691
120 13
4864
21779
61 50
162 98
12629
844.24
1 Assigned to 39 7% of the population not engaged in market work; assumes 40 hr unpaid work week, valued at $6.23/hr in traditional COI
and $12.46/hr in enhanced COI. Does not include lost unpaid work for employed people and may not include all unpaid work for people outside
the paid labor force.
2 Includes child care and homemaking (to the extent not covered in lost unpaid work days above), time with family, and recreation for people
within and outside the paid labor force, on days when subject is too sick to work.
3 Values lost work or leisure time for people caring for the ill. Traditional approach does not include lost leisure time Detail may not calculate to
totals due to independent rounding; Source Appendix L in LT2ESWTR EA (USEPA 2005a)
4 Analogous to lost productivity at work Includes reduced productivity in unpaid work and reduced enjoyment of recreation on days when sub-
ject is sick but engages in unpaid work or leisure activities anyway
The various loss categories were
calculated as follows; Medical costs are
a weighted average across the three
illness severity levels of actual costs for
doctor and emergency room visits,
medication, and hospital stays. Lost
paid work represents missed work time
of paid emploj^ees, valued at the median
pre-tax wage, plus benefits, of $20.82
hour. The average number of lost work
hours per illness day is 3.4 (this
assumes that 60 percent of the
population is in the paid labor force and
the loss is averaged over 7 days). The
weighted average number of lost work
days per case is 1.7 days. Medical costs
and lost work days reflect market
transactions. Medical costs are always
included in COI estimates and lost work
days are usually included in COI
estimates.
In the traditional COI estimate, an
equivalent amount of lost unpaid work
time was assigned to the 40 percent of
the population that are not in the paid
labor force. This includes homemakers,
students, children, retires, and
unemployed persons. This estimate
attempts to capture market-like work
(e.g., homemaking, volunteer work) that
is unpaid. EPA did not attempt to
calculate what percent of cases falls in
each of these five groups, or how many
hours per week each group works, but
rather assumed an across-the-board 40
hour unpaid work week. For this reason.
it likely overstates the value of unpaid,
market-like work, but EPA does not
have data on this. This time is valued
at $6.23 per hour, which is one half the
median post-tax wage (since work
performed by these groups is not taxed).
This is also approximately the median
wage for paid household domestic labor.
In the enhanced COI estimate, an
estimate of lost unpaid work days for
people outside the paid labor force was
made by assigning the value of $12.46
per hour to the same number of unpaid
work hours valued in the traditional
COI approach (i.e., 40 unpaid work
hours per week). Lost unpaid work for
employed people and any unpaid labor
beyond 40 hours per week for those not
in the labor market is shown as lost
leisure time in Table VI.C-2 for the
enhanced approach and is not included
in the traditional approach.
In the enhanced approach, all time
other than paid and market-like work
and sleep (8 hours per work day and 16
hours per non-work day) is valued at the
median after tax wage, or $12.46 per
hour. This includes lost unpaid
persona] work (e.g., chores, errands,
housework) and leisure time for people
within and outside the paid labor force.
The average number of unpaid work
hours per illness day is 2.3 (40 hours
per week averaged over 7 days x 40
percent of the population). Implicit in
this approach is that people would pay
the same amount not to be sick during
their leisure time as they require to give
up their leisure time to work (i.e., the
after tax wage). In reality, people might
be willing to pay either more than this
amount (if they were very sick and
suffering a lot) or less than this amount
(if they were not very sick and still got
some enjoyment out of activities such as
resting, reading, and watching TV), not
to be sick. Multiplying 10.3 hours by
$12.46 gives a value of about $128 for
a day of "lost" unpaid personal work
and leisure (i.e., lost utility of being
sick). The weighted average number of
lost leisure days per case is the same as
the weighted average number of lost
work days (1.7 days per case).
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
In addition, for days when an
individual is well enough to work but
is still experiencing symptoms, such as
diarrhea, the enhanced estimate also
includes a 30 percent loss of work and
leisure productivity, based on a study of
giardiasis illness (Harrington et al.
1985), which is similar to
cryptosporidiosis. Appendix P in the EA
describes similar productivity losses for
other illnesses such as influenza (35%-
73% productivity losses). In the
traditional COI analysis, productivity
losses are not included for either work
or nonwork time. The weighted average
number of reduced productivity days
per case, for both work and leisure, is
1.3 days.
EPA believes that losses in
productivity and lost leisure time are
unquestionably present and that these
categories have positive value;
consequently, the traditional COI
estimate understates the true value of
these loss categories. EPA notes that
these estimates should not be regarded
as upper and lower bounds. In
particular, the enhanced COI estimate
may not fully incorporate the value of
pain and suffering, as people may be
willing to pay more than $228 (the sum
of the valuation of lost work and leisure)
to avoid a day of illness. The traditional
COI estimate may not be a lower bound
because it includes a valuation for a lost
40 hour work week for all persons not
in the labor force, including children
and retirees. This may be an
overstatement of lost productivity for
these groups, which would depend on
the impact of such things as missed
school work or volunteer activities that
may be affected by illness.
As with the avoided mortality
valuation, the real wages used in the
COI estimates were increased by a real
income growth factor that varies by
year, but is the equivalent of about 1.9
percent over the 20 year period. This
approach of adjusting for real income
growth was recommended by the SAB
(USEPA 2000d) because the median real
wage is expected to grow each year (by
approximately 1.9 percent).
Correspondingly, the real income
growth factor of the COI estimates
increases by the equivalent of 1.9
percent per year (except for medical
costs, which are not directly tied to
wages). This approach gives a total COI
valuation per case in 2010 of $306
(undiscounted) for the traditional COI
estimate and $985 (undiscounted) for
the enhanced COI estimate; the
valuation in 2029 is $381
(undiscounted) for the traditional COI
estimate and $1,316 (undiscounted) for
the enhanced COI estimate. There is no
difference in the methodology for
calculating the COI over this 20 year
period of implementation; the change in
valuation is due to the underlying
change in projected real wages.
Table VI.C—3 summarizes the annual
cases of cryptosporidiosis illness and
associated deaths avoided due to the
LT2ESWTR proposal. Today's rule, on
average, is expected to reduce 89,375 to
1.459,126 illnesses and 20 to 314 deaths
annually after full implementation
(range based on the ICRSSL, ICRSSM,
and ICR data sets and model choice for
Cryptosporidium infectivity).
Table VI.C-3.-Summary of Annual Avoided Illness and Deaths
Data Set
Annual Illnesses Avoided
Low
Medium
High
Annual Deaths Avoided
Low
Medium
High
Total after Full implementation
ICR
ICRSSL
ICRSSM
358,732
89,375
177,101
964,360
230,730
455,170
1,459,126
372,507
711,123
76
20
39
207
52
100
314
84
156
Annual Average over 25 years
ICR
ICRSSL
ICRSSM
264,980
66,187
130,918
712,732
170,977
336,652
1 ,078,796
276,078
438,203
57
15
29
154
39
74
232
62
116
Source The LT2ESWTR Economic Analysis (USEPA 2005a)
Nole High, medium, and low estimates reflect the mean estimates for a range of dose-response modeling assumptions. See
Appendix N of the LT2ESWTR Economic Analysis (USEPA, 2005a)
Tables VI.C-4a and VI.C-4b show the
monetized present value of the benefit
for reductions in endemic
cryptosporidiosis estimated to result
from the LT2ESWTR for the enhanced
and traditional COI values, respectively.
Estimates are given for the ICR, ICRSSL,
and ICRSSM occurrence data sets and
for the three infectivity models.
With the enhanced COI and a 3
percent discount rate, the annual
present value of the mean benefit
estimate ranges from $177 million to
$2.8 billion; at a 7 percent discount rate.
the mean estimate ranges from $144
million to $2.3 billion. With the
traditional COI, the corresponding mean
benefit estimate at a 3 percent discount
rate ranges from $130 million to $2.0
billion; for a 7 percent discount rate, the
mean estimate ranges from $105 million
to $1.7 billion. None of these values
include the unquantified and
nonmonetized benefits listed in Table
VI.C-1.
BILLING CODE 6560-50-P
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735
Table VI.C-4a.-Summary of Quantified Benefits—Enhanced COI1 (Smillions, 2003$)
Data Set
Value of Benefits
($ Millions, 2003$)
Low
Medium
High
Annualized Value (at 3%, 25 Years)
ICR
ICRSSL
ICRSSM
$ 687
$ 177
$ 344
$ 1,853
$ 458
$ 886
$ 2,822
$ 744
$ 1,393
Annualized Value (at 7%, 25 Years)
ICR
ICRSSL
ICRSSM
$ 556
$ 144
$ 279
$ 1,501
$ 371
$ 718
$ 2,286
$ 603
$ 1,128
Table YI.C-4b.--Summary of Quantified Benefits—Traditional COI1 ($Millions, 2003$)
Data Set
Value of Benefits
($ Millions, 2003$)
Low
Medium
High
Annualized Value (at 3%, 25 Years)
ICR
ICRSSL
ICRSSM
$ 497
$ 130
$ 250
$ 1,341
$ 335
$ 644
$ 2,047
$ 546
$ 1,014
Annualized Value (at 7%, 25 Years)
ICR
ICRSSL
ICRSSM
$ 403
$ 105
$ 203
$ 1,089
$ 272
$ 523
$ 1,662
$ 443
$ 824
'The traditional COI only includes valuation for medical costs and lost work time (including some portion of unpaid household
production and other market like work) The enhanced COI also factors in valuations for lost personal time (non-\vorktime) such
as child care and homemaking (lo ihe extern nol co\ered by the traditional COI). time with family, and recreation, and lost
productivity in both work and leisure on days when workers ore ill but go to work anyway Source The LT2ESWTR Economic
Analysis (USEPA 2005a)
Note High, medium, and low estimates reflect the mean estimates for a range of dose-response modeling assumption1. See
Appendix N of the LT2ESWTR Economic Analysis (USEPA. 2005a)
BILLING CODE 6560-50-C
a. Filtered PWSs. Benefits to the
approximately 168 million people
served by filtered surface water and
GWUDI PWSs range from 34,000 to
702,000 reduction in mean annual cases
of endemic illness based on three
infectivity models and ICRSSL,
ICRSSM, and ICR data sets. In addition,
premature mortality is expected to be
reduced by an average of 6 to 116 deaths
annually.
b. Unfiltered PWSs. The 10 million
people served by unfiltered surface
water or GWUDI PWSs will see a
significant reduction in
cryptosporidiosis as a result of the
LT2ESWTR. In this population, the rule
is expected to reduce approximately
55,000 to 758,000 cases of illness and 14
to 197 premature deaths annually.
For unfiltered PWSs, only the ICR
data set is used to directly calculate
illness reduction because it is the only
data set that includes sufficient
information on unfiltered PWSs. Illness
reduction in unfiltered PWSs was
estimated for the ICRSSL and ICRSSM
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736
Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
data sets by multiplying the ICR
unfiltered PWS result by the ratio, for
the quantity estimated, between filtered
PWS results from the supplemental
survey data set (SSM or SSL) and
filtered PWS results from the ICR.
3. Timing of Benefits Accrual (latency)
In previous rulemakings, some
commenters have argued that the
Agency should consider an assumed
time lag or latency period in its benefits
calculations. The Agency has not
conducted a latency analysis for this
rule because cryptosporidiosis is an
acute illness; therefore, very little time
elapses between exposure, illness, and
mortality. However, EPA does account
for benefits and costs that occur in
future years by converting these to
present value estimates.
D. What Are the Costs of the
LT2ESWTR?
In order to estimate the costs of
today's rule, the Agency considered
impacts on PWSs and on States
(including territories and EPA
implementation in non-primacy States).
Summary information on these costs
follows, with more detailed information
in chapter 6 of the LT2ESWTR EA
(USEPA 2005a). A detailed discussion
of the requirements of today's rule is
located in section IV of this preamble.
1. Total Annualized Present Value Costs
Tables VI.D-1 summarizes the
annualized present value cost estimates
for the LT2ESWTR at 3 percent and 7
percent discount rates. The mean
annualized present value costs of the
LT2ESWTR are estimated to range from
approximately $93 to $133 million
using a 3 percent discount rate and $107
to $150 million using a 7 percent
discount rate. This range in mean cost
estimates is associated with the different
Cryptosporidium occurrence data sets.
In addition to mean estimates of costs,
the Agency calculated 90 percent
confidence bounds by considering the
uncertainty in Cryptosporidium
occurrence estimates and the
uncertainty around the mean unit
technology costs (USEPA 2005a).
PWSs will incur approximately 99
percent of the rule's total annualized
present value costs. States incur the
remaining rule costs. Table VI.D-2
shows the undiscounted initial capital
and one-time costs broken out by rule
component. A comparison of
annualized present value costs among
the rule alternatives considered by the
Agency is located in section VI,F of this
preamble.
BILLING CODE 6560-50-P
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738
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BILLING CODE 6560-50-C
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739
2. PWS Costs
Table VI.D-3 shows the number of
filtered and unfiltered PWSs that will
incur costs by rule provision. All PWSs
that treat surface water or GWUDI (j'.e.,
nonpurchased PWSs) will incur one-
time costs that include time for staff
training on rule requirements. PWSs
will incur monitoring costs to assess
source water Cryptosporidium levels,
though monitoring requirements vary by
PWS size (large vs. small) and PWS type
(filtered vs. unfiltered). Some PWSs will
incur costs for additional
Cryptosporidium treatment, where
required, and for covering or treating
uncovered finished water reservoirs.
Table VI.D-3.- Number of Filtered and Unfiltered PWSs and Plants Expected to Incur
Monitoring and Treatment Costs'
Dataset
ICR
ICRSSL
ICRSSM
Nonpurchased Systems and Plants
System Size
(population
served)
< 10,000
> 10,000
Total
< 10,000
> 10,000
Total
< 10,000
> 10,000
Total
Systems
Incurring
Implementation
Costs
A
5,663
1,493
7,156
Source Water Monitoring - Plants
Initial E.
Coli
Monitoring
B
5,575
1,733
7,308
Same as ICR
Same as ICR
Initial
Crypto
Monitoring
C
1,978
1,762
3,741
1,285
1,762
3,047
1,555
1,762
3,317
Future
E. coli
Monitoring
D
4,977
1,184
6,161
5,237
1,379
6,615
5,181
1,306
6,487
Future
Crypto
Monitoring
E
1,732
1,184
2,916
1,171
1,379
2,550
1,409
1,306
2,715
Plants
Adding
Treatment
F
2,205
677
2.882
1,428
440
1,868
1,729
531
2,260
Systems
with
Uncovered
Reservoirs
G
12
69
81
Same as
ICR
Same as
ICR
'Numbers shown for plants monitoring include nonpurchased plants only. Numbers shown for plants adding treatment include
both nonpurchased plants and a fraction of plants purchasing water that could not be linked to their wholesale plant Source
Chapter 6 of the LT2ESWTR Economic Analysis (L'SEPA 2005a)
a. Source wafer monitoring costs.
Source water monitoring costs are
structured on a per-plant basis. There
are three types of monitoring that plants
may be required to conduct—turbidity,
E. coli, and Cryptosporidium. Source
water turbidity is a common water
quality parameter used for plant
operational control. Also, to meet
SWTR, LT1ESWTR, and IESWTR
requirements, most PWSs have turbidity
analytical equipment in-house and
operators are experienced with turbidity
measurement. Thus, EPA assumes that
the incremental turbidity monitoring
burden associated with the LT2ESWTR
is negligible.
Filtered plants in small PWSs initially
will be required to conduct 1 year of
biweekly E. coli source water
monitoring. These plants will be
required to monitor for
Cryptosporidium if E. coli levels exceed
10 E. coli/100 mL for lakes and reservoir
sources or 50 E. coli/100 mL for flowing
stream sources. EPA estimated the
percent of small plants that would be
triggered into Cryptosporidium
monitoring as being equal to the percent
of large plants that would fall into any
bin requiring additional treatment.
Estimates of laboratory fees, shipping
costs, labor hours for sample collection,
and hours for reporting results were
used to predict PWS costs for initial
source water monitoring under the
LT2ESWTR. Table VI.D-4 summarizes
the present value of monitoring costs for
initial bin classification. Total present
value monitoring costs for initial bin
classification range from $45 million to
$59 million depending on the
occurrence data set and discount rate.
Appendix D of the LT2ESWTR EA
provides a full explanation of how these
costs were developed (USEPA 2005a).
b. Filtered PWSs treatment costs. The
Agency calculated treatment costs by
estimating the number of plants that
will add treatment technologies and
coupling these estimates with unit costs
($/plant) of the selected technologies.
Table VI.D-5 shows the number of
plants estimated to select different
treatment technologies; Table VI.D-6
summarizes the present value treatment
costs and annualized present value costs
for both filtered and unfiltered PWSs.
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
Table VI.D-4.- Summary of Present Value Monitoring Costs for Initial Bin Classification
($millions, 2003$)
System
Size
ICR
Mean
Confidence Bounds
5th %ile j 95th %ile
ICRSSL
Mean
Confidence Bounds
5th %ile
95th %ile
ICRSSM
Mean
Confidence Bounds
5th %ile
95th %ile
3 Percent
< 10,000
> 10,000
Total
$ 33.79
$ 25.22
$ 59.01
$ 32.11
$ 25.22
$ 57.33
$. 36.63
$ 25.22
$ 61.86
$ 25.24
$ 25.22
$ 50.46
$ 22.02
S 25.22
$ 47.24
$ 27.44
$ 25.22
$ 52.66
S 28.57
$ 25.22
S 53.79
$ 26.36
$ 25.22
$ 51.58
$ 30.43
$ 25.22
$ 55.66
7 Percent
< 10,000
> 10,000
Total
$ 29.05
$ 23.38
$ 52.42
$ 27.64
$ 2338
$ 51.01
$ 31.45
^$ 23.38
$ 54.82
$ 21 85 ' $ 1913
$ 2338 $ 23.38
$ 45.22 i S 42.50
S 23.70
S 23.38
S 47.07
S 24.65
$ 23.38
S 4802
$ 22.79
$ 23.38
$ 46.17
$ 26.22
$ 23.38
$ 49.60
Source Chapter 6 of the LT2ESWTR Economic Analysis (USEP'\ 2005a)
To estimate the number of filtered
plants that would select a particular
treatment technology, EPA followed a
two step process. First, the number of
plants that will be assigned to treatment
bins requiring additional treatment was
estimated. Second, the treatment
technologies that plants will choose to
meet these requirements was estimated
using a "least-cost decision tree." In this
estimate, EPA assumed that PWSs will
select the least expensive technology or
combination of technologies to meet the
log removal requirements of a given
treatment bin. Technology selections
were constrained by maximum use
percentages, which recognize that some
plants will not be able to implement
certain technologies because of site-
specific conditions. In addition, certain
potentially lower cost components of
the microbial toolbox, such as changes
to the plant intake, were not included
because EPA lacked data to estimate the
number of plants that could select it.
These limitations on technology use
may result in an overestimate of costs.
An in-depth discussion of the
technology selection methodology and
unit cost estimates can be found in
Appendices E and F of the LT2ESWTR
EA (USEPA 2005a).
Table VI.D-5.- Filtered Plant Technology Selection Forecasts
Technology
Selections1
Bag Filter
1 0 Log
Cartridge Filter
2.0 Log
Combined Filter
Performance
0.5 Log
In-bank Filtration
1.0 Log
MF/UF
2.5 Log
ICR
1,523
209
16
6
37
Data Set2
ICRSSL
1,219
20
12
5
13
ICRSSM
1,421
58
14
6
18
Technology
Selections'
Ozone
0.5 Log
Ozone
1.0 Log
Ozone
2.0 Log
Secondary Filter
1.0 Log
UV
2.5 Log
WS Control
0.5 Log
ICR
27
18 ,
10
o
979
0
Data Set'
ICRSSL
21
H
14
o
503
0
ICRSSM
25
16
4
0
641
0
'Some plants are projected to select more than one technology to meet LT2ESWTR bin requirements
'Forecasts represent the median occurrence distribution
Source. Chapter 6 of the LT2ESWTR Economic Analysis (USEPA 2005a)
c. Unfiltered PWSs treatment costs.
The LT2ESWTR requires all unfiltered
PWSs to achieve 2-log of inactivation if
their mean source water
Cryptosporidium concentration is less
than or equal to 0.01 oocysts/L and 3-
log of inactivation if it is greater than
0.01 oocysts/L. For most PWSs, UV
appears to be the least expensive
technology that can achieve these levels
of Cryptosporidium inactivation, and
EPA expects UV to be widely used by
unfiltered PWSs to meet today's rule
requirements. However, as with filtered
PWSs, EPA estimated that a small
percentage of plants would elect to
install a technology more expensive
than UV due to the configuration of
-------
Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
741
existing equipment or other factors.
Ozone is the next least expensive
technology that will meet the
inactivation requirements for some
PWSs and EPA estimated that it will be
used by plants that do not use UV.
All unfiltered PWSs must meet
requirements of the LT2ESWTR;
therefore, 100 percent of unfiltered
PWSs are estimated to add technology.
This assumes that no unfiltered PWSs
currently use these additional treatment
technologies. For this cost analysis, EPA
assumed that all very small unfiltered
PWSs will use UV; for all other
unfiltered PWS sizes, EPA estimated
that 90 percent will install UV and 10
percent will add ozone. Treatment costs
for unfiltered PWSs are included in
Table VI.D-6.
Table VI.D-6.-Total Present Value and Annualized Present Value Treatment Costs for
Filtered and Unfiltered Plants
Dataset
Capital - Present Value
Mean
A
5th %ile
B
95th %ile
c
O & M - Annualized
Mean
D
5th %ile
E
95th %ile
F
Total - Annualized
Mean
G
5th %ile
H
95th %ile
i
3 percent
ICR
ICRSSL
ICRSSM
$1,426.5
$ 998.5
$1,141.0
$1,128.4
$ 723.2
$ 8754
$1,780.9
$1,263.1
$1,4139
$ 337
$ 18.8
$ 23.2
$ 287
$ 14.2
$ 191
$ 39.6
$ 22.6
$ 27.2
$ 115.6
$ 76.1
$ 888
$ 93.5
$ 55.7
$ 69.4
S 141.9
$ 95.2
S 108.4
7 percent
ICR
ICRSSL
ICRSSM
$1,157.1
$ 812.2
$ 927.1
$ 915.3
$ 588.7
$ 711.5
$1,444.3
$1,027.0
$1,148.7
$ 294
$ 16.4 J
$ 203
$ 25.01
$ 12.4
$ 167
$ 34.6
$ 19.7
$ 23.7
$ 128.7
$ 86.1
$ 99.8
$ 103.6
$ 62.9
$ 77.7
$ 158.5
$ 107.9
$ 122.3
Source Chapter 6 of Ihe LT2ESWTR Economic Analysis (USEPA 2005a)
d. Uncovered finished water storage
facilities. As part of the LT2ESWTR,
PWSs with uncovered finished water
storage facilities must either cover the
storage facility or treat the discharge to
achieve inactivation and/or removal of
at least 2-log Cryptosporidium, 3-log
Giardia lamblia, and 4-log viruses. To
develop national cost estimates for
PWSs to comply with these provisions,
unit costs for each compliance
alternative and the percentage of PWSs
selecting each alternative were
estimated for the inventory of
uncovered finished water storage
facilities. From a recent survey of EPA
Regions, EPA estimates that there are
currently 81 uncovered finished water
storage facilities for which PWSs must
take steps to comply with the
LT2ESWTR. A full description of the
unit costs and other assumptions used
in this analysis is presented in Chapter
6 and Appendix I of the LT2ESWTR EA
(USEPA 2005a).
To comply with the treatment
requirements, EPA determined that the
least-cost treatment option is a
combination of chlorine and UV. For
PWSs with uncovered storage facility
capacities of 5 million gallons (MG) or
less, covering the storage facilities is the
least expensive alternative. Although
disinfection is the least expensive
alternative for the remaining PWSs, the
ability of a PWS to use booster
chlorination depends on their current
residual disinfectant type. Somewhat
less than half of all surface water PWSs
are predicted to use chloramination
following implementation of the Stage 2
DBPR. Adding chlorine to water that has
been treated with chloramines is not a
feasible alternative; therefore, the
fraction of PWSs projected to add UV
and booster chlorination to the effluent
from the uncovered storage facility was
estimated at 50 percent, with the
remaining 50 percent projected to add
covers.
Table VI.D-7 summarizes total
annualized present value costs for the
uncovered finished water storage
facility requirements using both 3 and 7
percent discount rates. EPA estimates
the total annualized present value cost
for covering or treating the water from
uncovered finished water storage
facilities to be approximately $10
million at a 3 percent discount rate and
$13 million at a 7 percent discount rate.
-------
742
Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
Table VI.D-7.- Estimated Annualized Present Value Cost for Uncovered Finished Water
Storage Facility Provision (Smillions, 2003$)
System Size
(Population
Served)
<1 0,000
>10,000
Total
Annualized Cost at 3%
Capital
$ 0.01
$ 6.52
$ 6.53
O&M
$ 0.00
$ 3.73
$ 3.73
Total
$ 0.01
$ 10.24
$ 10.26
Annualized Cost at 7%
Capital
$ 0.01
$ 9.39
$ 9.40
O&M
$ 0.00
$ 3.68
$ 3.68
Total
$ 0.02
$ 13.07
$ 13.08
Source Appendix II of the LT2ESWTR Economic Analysis (USEPA 2005a)
e. Future monitoring costs. Six years
after initial bin classification, filtered
and unfiltered PWSs must conduct a
second round of monitoring to assess
whether source water Cryptosporidium
levels have changed significantly. EPA
will evaluate new analytical methods
and surrogate indicators of microbial
water quality in the interim. While the
costs of monitoring are likely to change
in the 9 years following rule
promulgation, it is difficult to predict
how they will change. In the absence of
any other information, EPA assumed
that the laboratory costs will be the
same as for the initial monitoring.
All PWSs that conducted initial
monitoring were assumed to conduct
the second round of monitoring, except
for those PWSs that installed treatment
that achieves a total of 5.5-log or greater
treatment for Cryptosporidium as a
result of the rule. These PWSs are
exempt from monitoring under the
LT2ESWTR. EPA estimates that the cost
of the second round of source water
monitoring will range from $21 million
to $36 million, depending on the
occurrence data set and discount rate
used in the estimate. Appendix D of the
EA provides further details (USEPA
2005a).
f. Sensitivity analysis-influent
bromide levels on technology selection
for filtered plants. One concern with the
ICR data set is that it may not reflect
influent bromide levels in some PWSs
during droughts. High influent bromide
levels (the precursor for bromate
formation) limits ozone use because
some PWSs would not be able to meet
the MCL for bromate. EPA conducted a
sensitivity analysis to estimate the
impact that higher influent bromide
levels would have on technology
decisions. The sensitivity analysis
assumed influent bromide
concentrations of 50 parts per billion
(ppb) above the ICR concentrations.
Results of the analysis indicate that this
higher bromide level has a minimal
impact on costs.
3. State/Primacy Agency Costs
EPA estimates that States (including
primacy agencies) will incur an
annualized present value cost of $1.1 to
1.2 million using a 3 percent discount
rate and $1.4 million at 7 percent. State
implementation activities include
regulation adoption, program
implementation, training State staff,
training PWS staff, providing technical
assistance to PWSs, and updating
management systems. To estimate
implementation costs to States, the
number of full-time employees (FTEs)
per activity is multiplied by the number
of labor hours per FTE, the cost per
labor hour, and the number of States
and Territories.
In addition to implementation costs,
States will also incur costs associated
with managing monitoring data.
Because EPA will directly manage
reporting, approval, and analysis of
results from the initial round of
monitoring by large PWSs (serving at
least 10,000 people), States are not
predicted to incur costs for these
activities. States will, however, incur
costs associated with small PWS
monitoring. This is a result of the later
start of small PWS monitoring, which
will mean that some States will assume
primacy for small PWS monitoring. In
addition, States will review the second
round of monitoring results. States will
also incur costs for reviewing
technology compliance data and
consulting with PWSs regarding
disinfection benchmarking (for PWSs
that change their disinfection
procedures to comply with today's rule).
Appendix D of the LT2ESWTR EA
provides more information about the
State cost analysis (USEPA 2005a).
4. Non-Quantified Costs
EPA has quantified all the major costs
for this rule and has provided
uncertainty analyses to bound the over
or underestimates in the costs. There are
some costs that EPA has not quantified,
however, because of lack of data. For
example, some PWSs may merge with
neighboring PWSs to comply with this
rule. Such changes have both costs
(legal fees and connecting
infrastructure) and benefits (economies
of scale). Likewise, PWSs would incur
costs for procuring a new source of
water that may result in lower overall
treatment costs.
In addition, the Agency was unable to
predict the usage or estimate the costs
of several options in the microbial
toolbox. These options include intake
management and demonstrations of
performance. They have not been
included in the quantified analysis
because data are not available to
estimate the number of PWSs that may
use these toolbox options to comply
with the LT2ESWTR. Not including
these generally lower-cost options may
result in overestimation of costs.
E. What Are the Household Costs of the
LT2ESWTR?
Another way to assess a rule's impact
is to consider how it may impact
residential water bills. This analysis
considers the potential increase in a
household's water bill if a CWS passed
the entire cost increase resulting from
this rule on to its customers. This serves
as a tool to gauge potential impacts and
should not be construed as precise
estimates of potential changes to
individual water bills.
Included in this analysis are all PWS
costs, including rule implementation,
initial and future monitoring for bin
classification, additional
Cryptosporidium treatment, and treating
-------
Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
743
or covering uncovered finished water
storage facilities. Costs for
Cryptosporidium monitoring by small
PWSs, additional Cryptosporidium
treatment, and uncovered finished water
storage facilities are assigned only to the
subset of PWSs expected to incur them.
Although implementation and
monitoring represent relatively small,
one-time costs, they have been included
in the analysis to provide a complete
distribution of the potential household
cost. A detailed description of the
derivation of household costs is in
Chapter 6 and Appendix J of the
LT2ESTWR EA (USEPA 2005a).
For PWSs that purchase treated water
(i.e., purchased PWSs) from larger
nonpurchased PWSs, the households
costs are calculated based on the unit
treatment costs of the larger PWS but
included in the distribution for the size
category of the purchased PWS.
Households costs for these purchased
PWSs are based on the household usage
rates appropriate for the retail PWS and
not the PWS selling (wholesaling) the
water. This approach for purchased
PWSs reflects the fact that although they
will not face increased costs from
adding their own treatment, whatever
costs the wholesale PWS incurs will
likely be passed on as higher water
costs.
Table VI.E-1 shows the results of the
household cost analysis. In addition to
mean and median estimates, EPA
calculated the 90th and the 95th
percentiles. EPA estimates that all
households served by surface and
GWUDI sources will face some increase
in household costs due to
implementation of the LT2ESWTR. Of
all the households subject to the rule,
from 22 to 41 percent are projected to
incur costs for adding treatment,
depending on the Cryptosporidium
occurrence data set used.
Approximately 92 percent of the
households potentially subject to the
rule are served by PWSs serving at least
10,000 people and 99.8 percent are
served by PWSs serving at least 500
people; these PWSs experience the
lowest increases in costs due to
significant economies of scale. Over 95
percent of all households are estimated
to face an annual cost increase of less
than $12. Households served by small
PWSs that install advanced technologies
will face the greatest increases in annual
costs. EPA expects that the model's
projections for these PWSs are, in some
cases, overstated. Some PWSs are likely
to find alternative treatment techniques
such as other toolbox options not
included in this analysis, or sources of
water (ground water, purchased water,
or consolidating with another PWS] that
would be less costly than installing
more expensive treatment technologies.
Table VI.E-1.— Potential Annual Household Costs Impacts for the Preferred Regulatory
Option (2003$)
System Type/Size
Households
Mean
Median
90th
Percentile
95th
Percentile
Percent of
Systems with
Household
Cost Increase
<$12
Percent of
Systems with
Household
Cost Increase
<$120
ICR
All CWS
CWS< 10,000
CWS < 500
68,857,992
5,587,602
158,900
$2.59
$4.14
$13.09
$0.21
$0.56
$3.86
$6.43
$9.97
$28.66
$9.97
$14.79
$53.60
96.49%
91.19%
63.20%
99.99%
99.88%
98.87%
ICRSSL
All CWS
CWS< 10,000
CWS < 500
68,857,992
5,587,602
158,900
$1.67
$2.49
$8.58
$0.09
$0.36
$2.91
$6.37
$6.60
$1744
$6.42
$9.37
$29.01
97.96%
96.46%
72.61 %
100.00%
99.94%
99.50%
ICRSSM
All CWS
CWS < 10,000
CWS < 500
68,857,992'
5,587,602
158,900
$1.97
$300
$10.10
$0.09
$0.49
$2.90
$6.37
$7.02
$26.24
$6.85
$11.39
$35.97
97.47%
95.19%
68.73%
99.99%
99.93%
99.31%
ICR - High
All CWS
CWS< 10,000
CWS < 500
68,857,992
5,587,602
1 58,900
$2.84
$4.58
$721
$0.21
$0.61
$2.91
$6.43
$11 50
$16.81
$9.97
$15.30
$26.25
96.09%
90.22%
75.79%
99.99%
99.86%
99.80%
ICRSSL - Low
All CWS
CWS< 10,000
CWS < 500
68,857,992
5,587,602
158,900
$1.42
$2.06
S14.42
$0.03
$0.23
$4.79
$5.65
$6.58
S3000
$6.42
$7.47
$54.42
98.37%
97.21 %
62.07%
100.00%
99.96%
98.58%
Source Chapter 6 of the LT2ESWTR Economic Anal)sis (USEPA 2005a)
-------
744
Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
F. What Are the Incremental Costs and
Benefits of the LT2ESWTR?
Incremental costs and benefits are
those that are incurred or realized in
reducing Cryptosporidium exposures
from one regulatory alternative to the
next. Estimates of incremental costs and
benefits are useful in considering the
economic efficiency of different
regulatory alternatives evaluated by
EPA. Generally, the goal of an
incremental analysis is to identify the
most efficient regulatory alternative.
However, this analysis is incomplete
because some benefits from this rule are
unquantified and not monetized.
Incremental analyses should consider
both quantified and unquantified
(where possible) benefits and costs.
Usually an incremental analysis
implies increasing levels of stringency
along a single parameter, with each
alternative providing all the protection
of the previous alternative, plus
additional protection. However, the
regulatory alternatives evaluated for the
LT2ESWT R vary by multiple parameters
(e.g., treatment bin boundaries,
treatment requirements). The
comparison between any two
alternatives is, therefore, between two
separate sets of benefits, in the sense
that they may be distributed to
somewhat different population groups.
The regulatory alternatives, however,
do achieve increasing levels of benefits
at increasing levels of costs. As a result,
displaying incremental net benefits from
the baseline and alternative to
alternative is possible. Tables VI.F-la
and VI.F-lb show incremental costs,
benefits, and net benefits for the four
regulatory alternatives, A1-A4, shown
in Table VI.A-1, using the enhanced
and traditional COI, respectively. All
values are annualized present values
expressed in Year 2003 dollars. The
displayed values are the mean estimates
for each occurrence distribution and
infectivity model.
With the enhanced COI, incremental
costs are generally closest to
incremental benefits for A2. a more
stringent alternative than A3, which is
today's final rule. For the traditional
COI, incremental costs most closely
equal incremental benefits for A3 under
the majority of conditions evaluated.
G. Are There Benefits From the
Reduction of Co-Occurring
Contaminants?
While the quantified and monetized
benefits for the LT2ESWTR includes
only reductions in illness and mortality
attributable to Cryptosporidium, today's
rule will reduce exposure to and disease
from other microbial pathogens and, in
some cases, chemical contaminants.
-------
Federal Register/ Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
745
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All of the options in the microbial
toolbox that PWSs will implement to
comply with today's rule will also
reduce levels of other microbial
pathogens. For example, watershed
control programs and intake relocation
-------
Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
747
will cut overall pathogen levels by
reducing fecal contamination in the
source water. Membrane, bag, and
cartridge filters will remove pathogenic
protozoa like Giardia lamblia that are
similar in size to or larger than
Cryptosporidium. Lowering finished
water turbidity from conventional and
direct filtration will improve removal of
pathogens across a broad size range,
including viruses, bacteria, and
protozoa. Inactivation technologies like
ozone and UV are highly effective
against a large number of different
pathogen types.
Some membrane technologies that
PWSs may install to comply with the
LT2ESWTR can also reduce or eliminate
chemical contaminants including
arsenic, DBFs, and atrazine. The use of
UV for inactivation of Cryptosporidium
may reduce the chlorine dosage that
some PWSs must apply, which can
reduce levels of DBFs. EPA has recently
finalized a rule to further control arsenic
levels in drinking water and is
concurrently establishing the Stage 2
DBPR to address DBF control.
The extent to which the LT2ESWTR
can reduce the overall risk from other
contaminants has not been
quantitatively evaluated because EPA
lacks sufficient data on the co-
occurrence among Cryptosporidium and
other microbial pathogens and
contaminants. Further, due to the
difficulties in establishing which PWSs
would have multiple problems, such as
microbial contamination, arsenic, and
DBFs or any combination of the three,
no estimate was made of the potential
cost savings from addressing more than
one contaminant simultaneously.
H, Are There Increased Risks From
Other Contaminants?
It is unlikely that the LT2ESWTR will
result in a significant increase in risk
from other contaminants for most PWSs.
Many of the options that PWSs will
select to comply with the LT2ESWTR,
such as UV, additional or improved -
filtration, and watershed control, do not
form DBFs. Ozone, another technology
that is effective against
Cryptosporidium, does form DBFs (e.g.,
bromate). However, bromate is currently
regulated under the Stage 1 DBPR, and
PWSs will have to comply with this
regulation if they implement ozone to
meet the LT2ESWTR.
I. What Are the Effects of the
Contaminant on the General Population
and Groups Within the General
Populations That Are Identified as
Likely To he at Greater Risk of Adverse
Health Effects?
Section III of this preamble discusses
the health effects associated with
Cryptosporidium on the general
population as well as the effects on
other sensitive sub-populations. In
addition, health effects associated with
children and pregnant women are
discussed in greater detail in section
VII.G of this preamble.
/. What Are the Uncertainties in the
Risk, Benefit, and Cost Estimates for the
LT2ESWTR?
For today's final rule, EPA has
modeled the current baseline risk from
Cryptosporidium exposure through
drinking water, along with the reduction
in risk and the cost for various rule
alternatives. There is uncertainty in the
risk calculation, the benefit estimates,
the cost estimates, and the interaction
with other regulations. The LT2ESWTR
EA has an extensive discussion of
relevant uncertainties (USEPA 2005a),
and a brief summary of the major
uncertainties follows.
In regard to the risk estimates, the
most significant areas of uncertainty are
Cryptosporidium occurrence, treatment,
and infectivity. Among the three
available occurrence data sets, the ICR
plant-mean data were higher than the
ICRSSM or ICRSSL plant-mean data at
the 90th percentile. The reasons for
these differing results are not well
understood but may stem from year-to-
year variation in occurrence and
differences in the sampling and
measurement methods employed. The
ICRSSM and ICRSSL data sets use a
newer, more reliable sampling method
but include fewer plants and a shorter
time frame. Additional uncertainty is
associated with estimating finished
water occurrence because the analysis is
based on estimates of treatment plant
performance in removing
Cryptosporidium.
EPA has addressed some of the
uncertainty in occurrence by evaluating
benefits and costs for regulatory
alternatives with each Cryptosporidium
data set. Further, in the 2-dimensional
Monte Carlo simulation models used to
estimate risk, key parameters like
occurrence and treatment efficiency are
treated as both variable and uncertain.
This approach is intended to account for
the limitations in available data and the
recognized variability in these
parameters among PWSs.
EPA has also considered occurrence
data from additional sources. For
example, the LT2ESWTR EA discusses
a study of infectious Cryptosporidium
in the finished water of 82 filtration
plants by Aboytes et.al, 2004. The mean
level of infectious Cryptosporidium
measured in this study is higher than
EPA has estimated using the ICR,
ICRSSM, or ICRSSL data sets. This
result suggests that Cryptosporidium
occurrence at these plants may have
exceeded levels during the ICR and
ICRSS surveys or that EPA may have
overestimated the efficiency of
treatment plants in removing
Cryptosporidium.
In regard to Cryptosporidium
infectivity, EPA evaluated data from
human feeding studies conducted with
different Cryptosporidium isolates. The
measured infectivity of these isolates
varied widely, however, and how well
these isolates represent
Cryptosporidium that causes disease in
PWSs is uncertain. In addition,
extrapolating from the higher
Cryptosporidium dosing levels used in
the human feeding studies to the
exposure levels typical for drinking
water (e.g., one oocyst) is uncertain.
Another source of uncertainty is
differences that exist among populations
groups, such as individuals that are
more sensitive (e.g., children,
immunocompromised) or less sensitive
(previously infected adults).
EPA accounted for some of this
uncertainty in infectivity by treating the
human feeding study results for
different Cryptosporidium isolates as
random samples from a larger and
unknown environmental distribution of
Cryptosporidium infectivity. EPA used a
variety of models for this analysis, as
recommended by the SAB, and presents
results for a range of models to account
for uncertainty in model selection. In
addition, limited data on levels of
Cryptosporidium in the 1993
Milwaukee outbreak and associated
disease incidence suggest that the
infectivity of the Cryptosporidium
responsible for that outbreak is within
the range EPA has estimated for the risk
assessment in today's rule.
Unquantified benefits from the
reduction of co-occurring microbial
pathogens, as described earlier, are a
significant source of uncertainty in the
estimate of benefits for the LT2ESWTR.
EPA is also uncertain about the
monetization of avoided disease from
Cryptosporidium and has addressed this
uncertainty through the use of both
traditional and enhanced COI values for
benefits estimates.
While all of the significant costs of
today's rule have been identified by
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748
Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
EPA. there are uncertainties in the
estimates. Occurrence is the most
significant source of uncertainty in
costs, and EPA has attempted to account
for this uncertainty through the use of
different occurrence data sets and
Monte Carlo modeling as described
previously. EPA has also estimated
uncertainty in unit process costs for
treatment technologies. In addition, the
cost assessment for today's rule includes
sensitivity analyses, such an assessment
of the impact of influent bromide levels
on technology selection. Chapter 6 of
the LT2ESWT R EA provides a fuller
description of uncertainties in the cost
estimates (USEPA 2005a).
Last, EPA has recently finalized or is
currently finalizing new regulations for
arsenic, radon, Cryptosporidium in
small surface water PWSs, filter
backwash recycling, microbial
pathogens in PWSs using ground water,
and DBFs. These rules may have
overlapping impacts on some PWSs, but
the extent is not possible to estimate
due to lack of information on co-
occurrence. However, PWSs may choose
treatment technologies that will address
multiple contaminants. Therefore, while
the total cost impact of these drinking
water rules is uncertain, it is most likely
less than the estimated total cost of all
individual rules combined.
K. What Is the Benefit/Cost
Determination for the LT2ESWTR?
The Agency has determined that the
benefits of the LT2ESWTR justify the
costs. As discussed in section VII.C, the
rule provides a large reduction in
endemic cryptosporidiosis illness and
mortalities. More stringent alternatives
provide greater reductions but at higher
costs. Alternative Al provides the
greatest overall reduction in illnesses
and mortalities but the incremental
benefits between this option and
alternative A3 (today's final rule) are
relatively small while the incremental
costs are significant. In addition, today's
rule, unlike alternative Al, specifically
targets those PWSs whose source water
requires higher levels of treatment.
Tables VI.K-la and VI.K-lb present
net benefits for the four regulatory
alternatives that were evaluated.
Generally, analysis of net benefits is
used to identify alternatives where
benefits exceed costs, as well as the
alternative that maximizes net benefits.
However, as with the analysis of
incremental net benefits discussed
previously, the usefulness of this
analysis in evaluating regulatory
alternatives for the LT2ESWTR~is
somewhat limited because many
benefits from this rule are unquantified
and nonmonetized. Analyses of net
benefits should consider both quantified
and unquantified (where possible)
benefits and costs.
Also, as noted earlier, the regulatory
alternatives considered for the
LT2ESWTR vary both in the population
that experiences benefits and costs (i.e.,
treatment bin boundaries) and the
magnitude of the benefits and costs (i.e.,
treatment requirements). Consequently,
the more stringent regulatory
alternatives provide benefits to
population groups that do not
experience any benefit under less
stringent alternatives.
As shown by Tables VI.K-la and
VI.K-lb, net benefits are positive for all
four regulatory alternatives evaluated
under most occurrence and discount
rate scenarios. With both the enhanced
COI and traditional COI, net benefits are
highest for the alternative A3, which is
today's final rule, under the majority of
occurrence distributions and discount
rates evaluated.
Table VI.K-la.-Mean Net Benefits by Rule Option—Enhanced COI1 ($millions, 2003$)
Data
Set
ICR
Rule
Alternative
A1
A2
A3 - Preferred
A4
Annualized Value
3%, 25 Years
Low
$ 260
$ 498
$ 527
$ 550
Medium
$ 1,492
$ 1 ,708
$ 1,720
$ 1,673
High
$ 2,447
$ 2,655
$ 2,662
$ 2,566
7%, 25 Years
Low
$ 126
$ 366
$ 396
$ 427
Medium
$ 1 ,098
$ 1 ,333
$ 1,351
$ 1 ,328
High
$ 1,897
$ 2,112
$ 2,126
$ 2,061
iCRSSL
A1
A2
A3 - Preferred
A4
$ (223)
$ 43
$ 65
$ 87
$ 156
$ 366
$ 365
$ 347
$ 466
$ 647
$ 632
$ 589
$ (265)
$ 6
$ 32
$ 58
$ 15
$ 257
$ 264
$ 261
$ 292
$ 496
$ 491
$ 465
ICRSSM
A1
A2
A3 - Preferred
A4
$ (58)
$ 198
$ 218
$ 230
$ 578
$ 782
$ 780
$ 731
$ 1,104
$ 1,285
$ 1 ,267
$ 1,171
$ (132)
$ 130
$ 153
$ 172
$ 358
$ 591
$ 597
$ 569
$ 809
$ 1,010
$ 1 ,002
$ 935
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Federal Register/ Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
749
Table VI.K-lb.-Mean Net Benefits by Rule Option—Traditional CO!' ($millions, 2003$)
Data
Set
ICR
Rule
Alternative
A1
A2
A3 - Preferred
A4
Annualized Value
3%, 25 Years
Low
$ 64
$ 305
$ 337
$ 373
Medium
$ 967
^$ 1,190
$ 1 ,208
$ 1,193
High
$ 1 ,649
$ 1 ,870
$ 1 ,887
$ 1 ,842
7%, 25 Years
Low
$ (31)
$ 211
$ 243
$ 285
Medium
$ 675
$ 917
$ 939
$ 941
High
$ 1 ,256
$ 1,481
$ 1 ,502
$ 1 ,478
ICRSSL
A1
A2
A3 - Preferred
A4
$ (284)
$ (9)
$ 18
$ 46
$ 0
$ 233
$ 242
$ 242
$ 214
$ 432
$ 433
$ 418
$ (315)
$ (35)
$ (7)
$ 25
ICRSSM
A1
A2
A3 - Preferred
A4
$ (165)
$ 99
$ 124
$ 148
$ 306
$ 529
$ 538
$ 518
$ 676
$ 890
$ 889
$ 840
$ (218)
$ 50
$ 77
$ 106
$ (109)
$ 150
$ 166
$ 175
$ 90
$ 324
$ 331
$ 327
$ 138
$ 387
$ 402
$ 398
$ 465
S 692
$ 698
$ 668
'The traditional CO] only includes valuation for medical costs and lost work lime (including some portion of unpaid household
production) The enhanced COI also factors in valuations for lost personal time (non-worktime) such as child care and
homemaking (to the extent not covered by the traditional COI). time with family, and recreation, and lost productivity at work on
days when workers are ill but go to work anyway Source Chapter 8 of the LT7ESWTR Economic Analysis (USEPA 2005a)
High, medium, and low estimates reflect the mean estimates for a range of dose-response modeling assumptions See Appendix
N of the LT2ESWTR Econorruc Analysis
In addition to the net benefits of the
LT2ESWTR, the Agency used several
other techniques to compare costs and
benefits. For example, EPA calculated
the cost of the rule per case avoided.
Tables VI.K-2a, b and c show both the
cost of the rule per illness avoided and
cost of the rule per death avoided. This
cost effectiveness measure is another
way of examining the benefits and costs
of the rule but should not be used to
compare alternatives because an
alternative with the lowest cost per
illness/death avoided may not result in
the highest net benefits. With the
exception of alternative Al, the rule
options look favorable when the cost per
case avoided is compared to both the
weighted cost of cryptosporidiosis
illness ($844 and $274 for the two COI
approaches) and the mean value of a
statistical death avoided—
approximately $7 million dollars.
Additional information about this
analysis and other methods of
comparing benefits and costs can be
found in chapter 8 of the LT2ESWTR
EA (USEPA 2005a).
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
Table VI.K-2a.-Cost per Illness or Death Avoided1, Lou Estimate
Data
Set
ICR
ICRSSL
ICRSSM
Rule
Alternative
A4
A3 - Preferred
A2
A1
A4
A3 - Preferred
A2
A1
A4
A3 - Preferred
A2
A1
Cost Per Illness
Avoided ($)
3%
$ 398
$ 566
$ 739
$ 1,791
$ 1,241
$ 1 ,598
$ 2,073
$ 5,683
$ 690
$ 913
$ 1,207
$ 3,259
7%
$ 837
$ 1,172
$ 1,503
$ 3,546
$ 2,666
$ 3,366
$ 4,265
$ 11,259
$ 1,470
$ 1,913
$ 2.474
$ 6,456
Cost Per Death
Avoided
(SMillions, 2000S)
3%
$ 1 8
$ 27
S 35
$ 85
$ 53
$ 72
$ 94
$ 270
$ 3 1
$ 4.2
$ 56
$ 15.4
7%
$ 39
$ 56
$ 7 1
$ 167
$ 113
$ 15.1
$ 194
$ 533
$ 65
$ 89
$ 115
$ 30 6
Benefit/Cost
Ratio
(Enhanced COI)
3%
80
52
4.3
1 8
27
1 9
1 5
06
4 7
3.2
26
1 0
7%
56
37
3 1
1.3
1 9
1 3
L 1 1
0.5
33
2.3
1 9
07
Benefit/Cost Ratio
(Traditional COI)
3%
5 8
3 7
r~ 3 1
r 1 3
2.0
1 4
1 1
04
3 5
2 4
1 9
0.7
7%
4 1
2.7
22
0.9
1.4
1 0
08
03
24
1.7
1 4
0.5
Table VI.K-2b.-Cost per Illness or Death Avoided', Medium Estimate
Data
Set
ICR
ICRSSL
ICRSSM
Rule
Alternative
A4
A3 - Preferred
A2
A1
A4
A3 - Preferred
A2
A1
A4
A3 - Preferred
A2
A1
Cost Per Illness
Avoided (S)
3%
$ 147
$ 227
$ 275
$ 668
$ 476
$ 661
$ 808
$ 2,258
$ 265
$ 382
$ 473
$ 1,287
7%
$ 309
$ 468
$ 559
$ 1,322
$ 1,022
$ 1,385
$ 1.663
$ 4,472
$ 565
$ 796
$ 969
$ 2.548
Cost Per Death
Avoided (SMillions,
2000S)
3%
$ 07
$ 1 1
$ 1 3
^$ 3.1
$ 2.0
$ 29
$ 37
$ 106
$ 1.2
S 1.7
$ 2.2
$ 60
7%
$ 1.4
$ 2.2
$ 26
$ 62
$ 4.3
$ 6 1
$ 75
$ 21 0
$ 25
$ 36
$ 45
$ 119
Benefit/Cost
Ratio (Enhanced
COI)
3%
21 7
13 9
11 5
4.7
7 1
4 9
40
1 4
12 3
84
67
2 4
7%
153
10.0
8.3
3.5
4 9
35
2 9
1 0
8 5
59
48
1 8
Benefit/Cost Ratio
(Traditional COI)
3%
15.8
10.1
8.3
3 4
52
3 6
29
1 0
90
6 1
4 9
1 8
7%
11 1
7.2
6.0
2 5
36
2.6
2 1
0.7
63
4.3
35
1 3
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751
Table VI.K-2c.-Cost per Illness or Death Avoided1, High Estimate
Data
Set
ICR
ICRSSL
ICRSSM
1
Rule
Alternative
A4
A3 - Preferred
A2
A1
A4
A3 - Preferred
A2
A1
A4
A3 - Preferred
A2 |
A1
Cost Per Illness
Avoided (S)
3%
$ 97
$ 140
$ 182
$ 440
$ 295
$ 385
$ 500
$ 1,394
$ 170
$ 228
$ 302j
$ 820
7%
$ 205
$ 289
$ 369
$ 872
$ 633
$ 810
$ 1 ,029
$ 2,762
$ 363
$ 478
$ 619
$ 1,624
Cost Per Death
Avoided (SMillions,
2000S)
3%
$ 04
$ 0.7
$ 06
$ 2 1
$ 1 3
$ 1 7
$ 2.3
$ 6.6
$ 0.8
$ 1.1
$ 1.4
$ 39
7%
$ 09
$ 1 4
$ 1 7
$ 4 1
$ 27
$ 36
$ 46
$ 130
$ 1 6
$ 22
$ 29
$ 76
Benefit/Cost
Ratio
(Enhanced COI)
3%
330
21 2
175
7 2
11 4
80
65
23
19.3
13 1
10.6
38
7%
232
15.2
127
5 4
79
56
4.6
1.7
134
93
76
29
Benefit/Cost Ratio
(Traditional COI)
3%
24 0
15.3
12.7
5.2
85
59
4.7
1.6
142
9 6
77
28
7%
16.9
11.0
92
39
5 8
4.2
3.4
1.2
9.9
6.8
55
2.1
'The calculations presented here do not reflect discounting of the physical incidence of morbidity or mortality
Source Chapter 8 of the LT2ES\VTR Economic Analysis (USEPA 2005a)
Note High, medium, and low estimates reflect the mean estimates for a range of dose-response modeling assumptions
Appendix N of the LT2ESWTR Economic Analysis (USEPA, 2005a).
Sec
L. Summary? of Major Comments
EPA received significant public
comment on the analysis of benefits and
costs of the August 11, 2003 proposed
LT2ESWTR in the following areas:
Cryptosporidium occurrence, drinking
water consumption, Cryptosporidium
infectivity (i.e., dose-response), and
valuation of benefits. The following
discussion summarizes public comment
in these areas and EPA's responses.
1. Cryptosporidium Occurrence
With respect to the analysis of
Cryptosporidium occurrence, two areas
that received significant public
comment are the quality of the ICR and
ICRSS data sets (i.e., whether the
estimates derived from them should be
regarded as equally plausible) and the
treatment of samples in which no
Cryptosporidium is detected (i.e.,
observed zeros).
a. Quality of the ICR and ICRSS data
sets. As noted earlier, the ICR, ICRSSM,
and ICRSSL data sets differ significantly
in the high concentration portion of the
occurrence distribution (e.g., 90th
percentile). While the measurement
method employed in the ICRSS had
higher recovery and less variable
volumes assayed, the ICR produced a
much greater number of assays and
source waters sampled. Lacking a
technical basis to conclude that one data
set provides a better estimate, EPA
conducted separate analyses of costs
and benefits for all three data sets. EPA
requested comment on this approach.
The majority of commenters on this
issue supported EPA's approach of
analyzing the three data sets separately
to represent uncertainty about
occurrence. Two commenters suggested
that the ICR data would be more reliable
for estimating national occurrence due
to the larger number of samples, while
two others viewed the ICRSS data as
more reliable due to the improved
analytical method. No commenters
provided a technical analysis indicating
that one data set is more accurate. Given
these comments, EPA has retained the
approach of analyzing costs and benefits
separately for each occurrence data set
in today's final rule.
b. Treatment of observed zeros. One
commenter remarked that the majority
of samples in which no oocysts were
detected (i.e., observed zeros) likely
contained no oocysts in the volume
assayed. This commenter was
concerned with a parameter in EPA's
occurrence analysis model for "true
zero," which characterizes the
likelihood that a source water is entirely
free of Cryptosporidium at all times. In
EPA's model, the true zero parameter
was assigned a value of 0.1 percent. As
described in USEPA (2005b), EPA based
this assumption on the finding that
intensive sampling of surface waters
usually detects Cryptosporidium, even
in protected watersheds. The
commenter concluded, however, that
the true zero parameter resulted in the
model assigning a value of at least 1
oocyst to 99.9 percent of samples.
EPA responds that the true zero
parameter in the occurrence analysis
model does not operate in this way.
While the model is set-up to estimate
mean source water concentrations and
not the concentrations in individual
volumes assayed, the model recognizes
that the majority of samples in the ICR
and ICRSS contained no oocysts. The
model does assume that few, if any, of
the source waters sampled in these
surveys never contained a single oocyst
(the meaning of the true zero
parameter). EPA has clarified the
definition of the true zero parameter in
USEPA (2005b). EPA has also
conducted a sensitivity analysis in
which the true zero parameter was
varied from values of 0 to 50 percent,
with little effect on estimates of risk,
benefit, and cost for today's rule.
2, Drinking Water Consumption
Two commenters were concerned
with the distribution for drinking water
consumption that EPA used in the
proposed LT2ESWTR. This distribution,
which was based on a 1994-1996 survey
by the United States Department of
Agriculture (USDA), reflects water
consumption from all sources.
Commenters recommended two
modifications to this approach: (1)
Adjust the distribution to account for
factors like bottled water and boiled
water use; and (2) use an alternative
distribution from the USDA survey that
reflects consumption of community
water system (CWS) water only.
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Federal Register/Vol. 71, No. 3/Thursday. January 5, 2006/Rules and Regulations
In response, EPA agrees that the
distribution should be adjusted to
remove consumption attributable to
bottled water. For the consumption
distribution in today's final rule, EPA
subtracted bottled water usage, based on
information in the USDA survey, which
had the effect of reducing consumption
by approximately 14 percent in
comparison to the proposal. EPA does
not have information on the
effectiveness of heating water to make
coffee or tea for inactivating
Cryptosporidium and has not modified
the consumption distribution on this
basis.
EPA continues to believe that the
USDA distribution for consumption of
water from all sources, minus bottled
water consumption, provides the best
available estimate for consumption of
water from CWSs for people served by
CWSs. The USDA distribution for
consumption of CWS water only, which
a commenter recommended, includes
people not served by CWSs (e.g., people
with private wells). Inclusion these
individuals has the effect of
underestimating the consumption of
CWS water for people served by CWSs
in this distribution. In contrast, the
distribution for consumption of water
from all sources includes people not
served by CWSs and the sources those
people use (e.g., private wells). This
avoids the problem of underestimating
consumption for individuals served by
CWS. Accordingly, EPA has retained the
use of this distribution in today's final
rule, with the adjustment stated
previously for bottled water
consumption.
3. Cryptosporidium Infectivity
In regard to Cryptosporidium
infectivity (i.e., dose-response
assessment), EPA received significant
comment on limitations in the human
feeding studies (e.g. representativeness
of Cryptosporidium isolates used in the
studies, numbers of subjects) and
uncertainty in extrapolating from high
study doses to low drinking water
doses. EPA believes that the statistical
analysis of dose-response data, as
described in USEPA (2005a), properly
accounted for these limitations and
uncertainties.
The statistical models used by EPA
treated the isolates studied as a random
sample from a larger population of
environmental isolates, treated the
subjects studied as a random sample
from the larger population of healthy
individuals, and treated each
individual's outcome as a chance event,
where the infection probability is a
function of the challenge dose.
Collectively, these uncertainties
contributed to the significant
uncertainty in EPA's estimate of the
likelihood of infection given one oocyst
ingested.
Since the LT2ESWTR proposal, EPA
has reviewed results from additional
human feeding studies with
Cryptosporidium isolates and analyzed
data from these and the feeding studies
considered for the proposal with
additional dose-response models
(USEPA 2005a). As described in Chapter
5 and Appendix N of the LT2ESWTR
EA, the infectivity estimates from the
proposal are near the middle of the
range of estimates derived with the
additional feeding study data and dose-
response models. Further, the mean
estimates from these new analyses fall
within the 90th percentile uncertainty
bounds for infectivity estimates from the
proposal (USEPA 2005a). Consequently,
EPA believes that the infectivity
estimates from the additional feeding
study data and dose-response models
are consistent with and supportive of
the estimates of infectivity from the
proposal. Further, EPA's estimates of
infectivity are consistent with data on
the infectivity of Cryptosporidium in
the 1993 Milwaukee outbreak (USEPA
2005a).
4. Valuation of Benefits
In the area of benefits valuation, EPA
received significant public comment on
the valuation of morbidity, valuation of
lost time under the Enhanced COI
approach, and unquantified benefits.
a. Valuation of morbidity. EPA
received a comment that endemic cases
that do not show up in public health
surveillance data may be too mild (and
perhaps even asymptomatic) to be
economically significant. EPA believes
endemic cases are significant in terms of
public health risk and economic
impacts. As discussed earlier, only a
small fraction of the millions of cases of
gastrointestinal illnesses are traced to a
specific illness (such as
cryptosporidiosis); yet endemic disease
clearly exists and those illnesses, even
if mild, have public health
consequences and economic impacts
(e.g., missed work). For example, the
benefits model in the EA assumes that
88 percent of all cases are mild, and yet
those illnesses represent significant
impacts nationally. Further, the risk
assessment model separately computes
infections and illnesses. Thus,
asymptomatic infections are excluded;
only avoided illnesses are assigned
monetary benefits.
b. Valuation of lost time under the
enhanced cost of illness (COI) approach.
One commenter extensively questioned
the approach used to value lost leisure
and nonwork time under the Enhanced
COI approach, noting concerns about
the relationship of the approach to
standard economics practices, the
plausibility of the resulting values, and
the extent of peer review. The following
discussion summarizes EPA's responses
on these issues.
As discussed in detail in the EA
(USEPA 2005a), EPA recognizes that the
preferred approach for valuing health
risk reductions is to rely on estimates of
individual willingness to pay (WTP). In
the absence of suitable WTP estimates,
analysts often rely on approaches
similar to the Traditional COI approach
used for this rule, as noted by the
commenter. However, empirical
research as well as theoretic concerns
suggest that these types of COI
approaches will generally understate
true WTP.
EPA designed the Enhanced COI
approach to correct for one potential
source of understatement—the impact of
illness on unpaid work and leisure time.
While the Enhanced COI approach is
innovative, it is rooted in standard
welfare economic theory and builds on
approaches used to value time in
numerous studies in the labor,
transportation, recreation, and health
economics literature. The commenter is
concerned, however, that the Enhanced
COI approach values nonwork time at a
higher rate than many recreational
studies, several of which value travel
time at one-third of the wage rate. EPA's
extensive review of the recreational
literature suggests, however, that there
is no consensus regarding the value of
travel time, as discussed in the
Appendix P of the EA (USEPA 2005a).
In addition, travel has both pleasant and
unpleasant aspects and hence may be
valued less than other leisure activities,
many of which may be valued at a rate
higher than foregone wages.
To test the plausibility of the results.
the commenter compares the value of a
"lifetime case" of cryptosporidiosis to
the value of statistical life (VSL) and
suggests that the results (which show
that such a case would be roughly 70
percent of VSL) are improbably high.
However, EPA believes that this
comparison is seriously flawed. There is
no generally accepted standard for
determining whether values for nonfatal
risk reductions are "reasonable"
compared to values for fatal risk
reductions. In addition, the calculation
of the value of a lifetime case of
cryptosporidiosis contains several
computational errors, and represents the
loss of all waking time (not just losses
attributable to cryptosporidiosis) and so
is seriously overstated. Perhaps most
important, the approach used to value
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753
time losses in the Enhanced COI
estimate is appropriate only for
marginal changes in time use; it is not
appropriate for the types of lifetime
changes considered in the comparison.
The Enhanced COI estimates are
based on an approach developed in the
EPA report, Valuing Time Losses Due to
Illness under the 1996 Amendments to
the Safe Drinking Water Act (USEPA
2005e). This report has been subject to
two rounds of independent peer review.
In conclusion, EPA believes that
including the Enhanced COI in
conjunction with the Traditional COI is
justified theoretically and that including
both measures increases EPA's ability to
understand the impacts of the rule.
VII. Statutory and Executive Order
Reviews
A. Executive Order 12866: Regulatory
Planning and Review
Under Executive Order 12866, [58 FR
51735, (October 4, 1993)] the Agency
must determine whether the regulatory
action is "significant" and therefore
subject to OMB review and the
requirements of the Executive Order.
The Order defines "significant
regulatory action" as one that is likely
to result in a rule that may:
(I) Have an annual effect on the
economy of $100 million or more or
adversely affect in a material way the
economy, a sector of the economy,
productivity, competition, jobs, the
environment, public health or safety, or
State, local, or Tribal governments or
communities;
(2) Create a serious inconsistency or
otherwise interfere with an action taken
or planned by another agency;
(3) Materially alter the budgetary
impact of entitlements, grants, user fees,
or loan programs or the rights and
obligations of recipients thereof; or
(4) Raise novel legal or policy issues
arising out of legal mandates, the
President's priorities, or the principles
set forth in the Executive Order.
Pursuant to the terms of Executive
Order 12866, it has been determined
that this rule is a "significant regulatory
action" because it may have an annual
effect on the economy of $100 million
or more (estimated annual costs are $93
to 133 million and $107 to 150 million
at 3 and 7 percent discount rates,
respectively). As such, this action was
submitted to OMB for review. Changes
made in response to OMB suggestions or
recommendations are documented in
the public record.
B. Paperwork Reduction Act
The Office of Management and Budget
(OMB) has approved the information
collection requirements contained in
this rule under the provisions of the
Paperwork Reduction Act, 44 U.S.C.
3501 et seq. and has assigned OMB
control number 2040-0266.
The information collected as a result
of this rule will allow the States and
EPA to determine appropriate
requirements for specific PWSs and to
evaluate compliance with the rule. For
the first 3 years after LT2ESWTR
promulgation, the major information
requirements concern monitoring
activities and compliance tracking. The
information collection requirements are
mandatory (40 CFR part 141) and the
information collected is not
confidential.
The estimate of annual average
burden hours for the LT2ESWTR during
the first three years following
promulgation is 141,295 hours. The
annual average cost estimate is $4.4
million for labor and $7 million per year
for operation and maintenance
including lab costs (which is a purchase
of service). The burden hours per
response is 0.63 hours and the cost per
response is $50.35. The frequency of
response (average responses per
respondent) is 90.3, annually. The
estimated number of likely respondents
is 2,503 (the product of burden hours
per response, frequency, and
respondents does not total the annual
average burden hours due to rounding).
Note that the burden hour estimates for
the first 3-year cycle include some large
PWS but not small PWS monitoring.
Conversely, burden estimate for the
second 3-year cycle will include
remaining monitoring for large systems
(those serving between 10.000 and
49,999 people) and small PWS
monitoring, but not for large PWS
serving 50,000 or more, which will have
been completed by then.
Burden means the total time, effort, or
financial resources expended by persons
to generate, maintain, retain, or disclose
or provide information to or for a
Federal agency. This includes the time
needed to review instructions; develop,
acquire, install, and utilize technology
and systems for the purposes of
collecting, validating, and verifying
information, processing and
maintaining information, and disclosing
and providing information; adjust the
existing ways to comply with any
previously applicable instructions and
requirements; train personnel to be able
to respond to a collection of
information; search data sources;
complete and review the collection of
information; and transmit or otherwise
disclose the information.
An agency may not conduct or
sponsor, and a person is not required to
respond to a collection of information
unless it displays a currently valid OMB
control number. The OMB control
numbers for EPA's regulations in 40
CFR are listed in 40 CFR part 9. In
addition, EPA is amending the table in
40 CFR part 9 of currently approved
OMB control numbers for various
regulations to list the regulatory
citations for the information
requirements contained in this final
rule.
C. Regulatory Flexibility Act
The Regulatory Flexibility Act (RFA)
generally requires an agency to prepare
a regulatory flexibility analysis for any
rule subject to notice and comment
rulemaking requirements under the
Administrative Procedure Act or other
statute unless the agency certifies that
the rule will not have a significant
economic impact on a substantial
number of small entities. Small entities
include small businesses, small
organizations, and small governmental
jurisdictions.
The RFA provides default definitions
for each type of small entity. Small
entities are defined as: (1) a small
business as defined by the Small
Business Administrations's (SBA)
regulations at 13 CFR 121.201; (2) a
small governmental jurisdiction that is a
government of a city, county, town,
school district or special district with a
population of less than 50,000; and (3)
a small organization that is any "not-for-
profit enterprise which is independently
owned and operated and is not
dominant in its field." However, the
RFA also authorizes an agency to use
alternative definitions for each category
of small entity, "which are appropriate
to the activities of the agency" after
proposing the alternative definition(s) in
the Federal Register and taking
comment. 5 U.S.C. 601(3)-(5). In
addition, to establish an alternative
small business definition, agencies must
consult with SBA's Chief Counsel for
Advocacy.
For purposes of assessing the impacts
of today's rule on small entities, EPA
considered small entities to be public
water systems serving 10,000 or fewer
persons. As required by the RFA, EPA
proposed using this alternative
definition in the Federal Register (63 FR
7620, February 13, 1998), requested
public comment, consulted with the
Small Business Administration (SBA),
and finalized the alternative definition
in the Consumer Confidence Reports
regulation (63 FR 44511, August 19,
1998). As stated in that Final Rule, the
alternative definition is applied to this
regulation as well.
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
After considering the economic
impacts of today's final rule on small
entities, I certify that this action will not
have a significant economic impact on
a substantial number of small entities.
The small entities directly regulated by
this final rule are PWSs serving fewer
than 10,000 people. We have
determined that 152 of the 6,574 small
PWSs, or 2.3 percent, regulated by the
LT2ESWTR will experience an impact
of 1 percent or greater of average annual
revenues; further, 18 PWSs, which are
0.3 percent of the small PWSs regulated
by this rule, will experience an impact
of 3 percent or greater of average annual
revenues (see Table VII.C-l).
TABLE VII.C-1.—ANNUALIZED COMPLIANCE COST AS A PERCENTAGE OF REVENUES FOR SMALL ENTITIES (2003$)
PWSs by ownership type and system
size
Small Government PWSs
Small Business PWSs
Small Organization PWSs .
All Small Entitv PWSs
Number of
small
systems
A
2,827
2,452
1,295
6.574
Percent of
small
systems
B
43
37
20
100
Average
annual
estimated
revenues
per sys-
tem(S)
C
2,649,186
2,555,888
4,750,838
2.981.331
Systems experiencing
costs of >1% of their
revenues
Number of
systems
D=A*E
65
57
5
152
Percent of
systems
E
2.3
2.3
0.4
2.3
Systems experiencing
costs of >3% of their
revenues
Number of
systems
F=A*G
8
7
2
18
Percent of
systems
G
03
0.3
0.1
0.3
Note: Detail may not add due to independent rounding Data are based on the means of the highest modeled distributions using Information
Collection Rule occurrence data set Costs are discounted at 3 percent, summed to present value, and annualized over 25 years Source Chap-
ter 7 and Appendix H of the LT2ESWTR EA (USEPA 2005a).
Although this final rule will not have
a significant economic impact on a
substantial number of small entities.
EPA nonetheless has tried to reduce the
impact of this rule on small entities. The
LT2ESWTR contains a number of
provisions to minimize the impact of
the rule on PWSs generally, and on
small PWSs in particular. The risk-
targeted approach of the LT2ESWTR
will impose additional treatment
requirements only on the subset of
PWSs with the highest vulnerability to
Cryptosporidium, as indicated by source
water pathogen levels. This approach
will spare the majority of PWSs from the
cost of installing additional treatment.
Also, development of the microbial
toolbox under the LT2ESWTR will
provide both large and small PWSs with
broad flexibility in selecting cost-
effective compliance options to meet
additional treatment requirements.
Small PWSs will monitor for E. coli
as a screening analysis for source waters
with low levels of fecal contamination.
Cryptosporidium monitoring will only
be required of small PWSs if they
exceed the E. coli trigger value. Because
E. coli analysis is much cheaper than
Cryptosporidium analysis, the use of E.
coli as a screen will significantly reduce
monitoring costs for the majority of
small PWSs. Further, small PWSs will
not be required to initiate their
monitoring until large PWS monitoring
has been completed. This will provide
small PWSs with additional time to
become familiar with the rule and to
prepare for monitoring and other
compliance activities.
Funding may be available from
programs administered by EPA and
other Federal agencies to assist small
PWSs in complying with the
LT2ESWTR. The Drinking Water State
Revolving Fund (DWSRF) assists PWSs
with financing the costs of
infrastructure needed to achieve or
maintain compliance with SDWA
requirements. Through the DWSRF,
EPA awards capitalization grants to
States, which in turn can provide low-
cost loans and other types of assistance
to eligible PWSs. Loans made under the
program can have interest rates between
0 percent and market rate and
repayment terms of up to 20 years.
States prioritize funding based on
projects that address the most serious
risks to human health and assist PWSs
most in need. Congress provided $1.275
billion for the DWSRF program in fiscal
year 1997, and has provided an
additional $4.113 billion for the DWSRF
program for fiscal years 1999 through
2003.
The DWSRF places an emphasis on
small and disadvantaged communities.
States must provide a minimum of 15%
of the available funds for loans to small
communities. A State has the option of
providing up to 30% of the grant
awarded to the State to furnish
additional assistance to State-defined
disadvantaged communities. This
assistance can take the form of lower
interest rates, principal forgiveness, or
negative interest rate loans. The State
may also extend repayment terms of
loans for disadvantaged communities to
up to 30 years. A State can set aside up
to 2% of the grant to provide technical
assistance to PWSs serving communities
with populations fewer than 10,000.
In addition to the DWSRF, money is
available from the Department of
Agriculture's Rural Utility Service
(RUS) and Housing and Urban
Development's Community
Development Block Grant'(CDBG)
program. RUS provides loans,
guaranteed loans, and grants to improve.
repair, or construct water supply and
distribution systems in rural areas and
towns of up to 10,000 people. In fiscal
year 2003, RUS had over $1.5 billion of
available funds for water and
environmental programs. The CDBG
program includes direct grants to States,
which in turn are awarded to smaller
communities, rural areas, and colonas in
Arizona, California, New Mexico, and
Texas and direct grants to U.S.
territories and trusts. The CDBG budget
for fiscal year 2003 totaled over $4.4
billion.
Although not required by the RFA to
convene a Small Business Advocacy
Review (SBAR) Panel because EPA~
determined that the proposed rule
would not have a significant economic
impact on a substantial number of small
entities, EPA did convene a panel to
obtain advice and recommendations
from representatives of the small
entities potentially subject to this rule's
requirements. For a description of the
SBAR Panel and stakeholder
recommendations, please see the
proposed rule (USEPA 2003a).
D. Unfunded Mandates Reform Act
Title II of the Unfunded Mandates
Reform Act of 1995 (UMRA), Public
Law 104—4, establishes requirements for
Federal agencies to assess the effects of
their regulatory actions on State, local,
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755
and Tribal governments and the private
sector. Under section 202 of the UMRA,
EPA generally must prepare a written
statement, including a cost-benefit
analysis, for proposed and final rules
with "Federal mandates" that may
result in expenditures to State, local and
Tribal governments, in the aggregate, or
to the private sector, of $100 million or
more in any one year. Before
promulgating an EPA rule for which a
written statement is needed, section 205
of the UMRA generally requires EPA to
identify and consider a reasonable
number of regulatory alternatives and
adopt the least costly, most cost-
effective or least burdensome alternative
that achieves the objectives of the rule.
The provisions of section 205 do not
apply when they are inconsistent with
applicable law. Moreover, section 205
allows EPA to adopt an alternative other
than the least costly, most cost-effective
or least burdensome alternative if the
Administrator publishes with the final
rule an explanation why that alternative
was not adopted.
Before EPA establishes any regulatory
requirements that may significantly or
uniquely affect small governments,
including Tribal governments, it must
have developed under section 203 of the
UMRA a small government agency plan.
The plan must provide for notifying
potentially affected small governments,
enabling officials of affected small
governments to have meaningful and
timely input in the development of EPA
regulatory proposals with significant
Federal intergovernmental mandates,
and informing, educating, and advising
small governments on compliance with
the regulatory requirements.
EPA has determined that this rule
contains a Federal mandate that may
result in expenditures of $100 million or
more for State, local, and Tribal
governments, in the aggregate, or the
private sector in any one year.
Accordingly, EPA has prepared under
section 202 of the UMRA a written
statement which is summarized below.
Table VII.D-1 illustrates the
annualized public and private costs for
the LT2ESWTR.
Table VII.D-1.- Public and Private Costs of the LT2ESWTR
Publicly Owned PWS
Costs
State Costs
Tribal Costs
Total Public Costs
Total Private Costs
Total Costs
Range of Annualized Costs
(Millions, 2003$)
3% Discount Rate
$57.4 - $82.7
$1 1 - $1.2
$0.2 - $0.2
$58.6 - 84.1
$34.3 - 49.4
$92.9 - $133.4
7% Discount Rate
$65.9 - $88.6
$1.4 - 1.4
$0.2 - $0.3
$67.5 - 90.3
$39.3 - 60.2
$106.8 - 150.5
Percent of Total Cost
61.8% - 62.0%
1.2% - 0.9%
0.2% - 0.2%
63.1% - 63.0%
36.9% - 37.0%
100.0% - 100.0%
Note: The ranges represent the ICRSSL (lowest) and Information Collection Rule (highest) modeled Cryptosporidium
occurrence distributions Detail may not add due to independent rounding
Source: The LT2ESWTR Economic Analysis (USEPA 2005a).
A more detailed description of this
analysis is presented in Economic
Analysis for the LT2ESWTR (USEPA
2005a).
As noted in section III, today's final
rule is promulgated pursuant to section
1412 (b)(l)(A) of the Safe Drinking
Water Act (SOWA), as amended in 1996,
which directs EPA to promulgate a
national primary drinking water
regulation for a contaminant if EPA
determines that the contaminant may
have an adverse effect on the health of
persons, occurs in PWSs with a
frequency and at levels of public health
concern, and regulation presents a
meaningful opportunity for health risk
reduction.
Section VI of this preamble discusses
the cost and benefits associated with the
LT2ESWTR. Details are presented in the
Economic Analysis for the LT2ESTWR
(USEPA 2005a). EPA quantified costs
and benefits for four regulatory
alternatives. The four alternatives are
described in section VI. Table VII.D—2
summarizes the range of annual costs
and benefits for each alternative.
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Table VII.D-2.- Annual Benefits and Costs of Rule Alternatives ($mi)lion, 2003$)
Regulatory Alternative
Alternative A1
Alternative A2
Alternative A3
(Preferred Alternative)
Alternative A4
Enhanced COI
Range of
Annualized
Benefits (3%)
221 - 2891
191 - 2851
177 - 2822
155 - 2661
Traditional CO!
Range of
Annualized
Benefits (3%)
160 - 2093
139 - 2066
130 - 2047
115 - 1937
Enhanced COI
Range of
Annualized
Benefits (7%)
221 - 2341
154 - 2309
144 • 2286
126 - 2156
Traditional COI
Range of
Annualized
Benefits (7%)
130 - 1700
113 - 1678
105 - 1662
93 - 1574
Range of
Anualized Costs
(3%)
^_ 403-403
123 - 163
93 - 133
57 - 81
Range of
Anualized Costs
(7%)
437 - 436
139 - 182
107 - 150
68 - 93
Source. The LT2ESWTR Economic Analysis (USEPA 2005a)
To meet the UMRA requirement in
section 202, EPA analyzed future
compliance costs and possible
disproportionate budgetary effects. The
Agency believes that the cost estimates,
indicated earlier and discussed in more
detail in section VI of this preamble.
accurately characterize future
compliance costs of today's rule.
In analyzing disproportionate
impacts. EPA considered the impact on
(1) different regions of the United States.
(2) State, local, and Tribal governments,
(3) urban, rural and other types of
communities, and (4) any segment of the
private sector. This analysis is presented
in Chapter 7 of Economic Analysis for
the LT2ESWTR (USEPA 2005a).
EPA has concluded that the
LT2ESWTR will not cause a
disproportionate budgetary effect. This
rule imposes the same requirements on
PWSs nationally and does not
disproportionately affect any segment.
This rule will treat similarly situated
PWSs (in terms of size, water quality.
available data, installed technology, and
presence of uncovered finished storage
facilities) in similar (proportionate)
ways, without regard to geographic
location, type of community, or segment
of industry. The LT2ESWTR is a rule
where requirements are proportionate to
risk. Although some groups may have
differing budgetary effects as a result of
the LT2ESWTR, those costs are
proportional to the need for greater
information (monitoring) and risk posed
(degree of treatment required). The
variation in cost between large and
small PWSs is due to economies of scale
(a larger PWS can distribute cost across
more customers). Regions will have
varying impacts due to the number of
affected PWSs.
Under UMRA section 202, EPA is
required to estimate the potential
macro-economic effects of the
regulation. These types of effects
include those on productivity, economic
growth, full employment, creation of
productive jobs, and international
competitiveness. Macro-economic
effects tend to be measurable in
nationwide econometric models only if
the economic impact of the regulation
reaches 0.25 percent to 0.5 percent of
Gross Domestic Product (GDP). In 2003,
real GDP was $10,398 billion, so a rule
would have to cost at least $26 billion
to have a measurable effect. A regulation
with a smaller aggregate effect is
unlikely to have any measurable impact
unless it is highly focused on a
particular geographic region or
economic sector.
The macro-economic effects on the
national economy from the LT2ESWTR
should not have a measurable effect
because the total annual costs for
today's rule range from $93 million to
$133 million based on median
Cryptosporidium occurrence
distributions from the ICRSSL and
Information Collection Rule data sets
and a discount rate of 3 percent ($107
to $150 million at a 7 percent discount
rate). These annualized figures will
remain constant over the 25-year
implementation period that was
evaluated, while GDP will probably
continue to rise. Thus, the LT2ESWTR
costs as a percentage of the national
GDP will only decline over time. Costs
will not be highly focused on a
particular geographic region or sector.
Consistent with the intergovernmental
consultation provisions of section 204 of
the UMRA, EPA initiated consultations
with the governmental entities affected
by this rule prior to the proposal. A
description of the consultations is found
in the proposed rule (USEPA 2003a).
As required under section 205 of
UMRA, EPA considered several
regulatory alternatives to address PWSs
at risk for contamination by microbial
pathogens, specifically including
Cryptosporidium. A detailed discussion
of these alternatives can be found in
section VI of the preamble and also in
the Economic Analysis for the
LT2ESWTR (USEPA 2005a).
Among the regulatory alternatives
considered for the LT2ESWTR, as
described in section VI, EPA believes
the alternative in today's rule is the
most cost-effective that achieves the
objectives of the rule. The objective of
the LT2ESWTR is to achieve feasible
risk reduction from Cryptosporidium
and other pathogens in vulnerable PWSs
where current regulations do not
provide sufficient protection.
EPA evaluated a less costly and less
burdensome alternative. However, that
alternative would provide no benefit to
several thousand consumers who, under
the alternative in today's final rule, will
receive benefits that most likely exceed
their costs, based on EPA estimates.
This is illustrated in the LT2ESWTR
Economic Analysis (USEPA 2005a). By
failing to reduce risk for consumers
where additional treatment
requirements would be cost-effective.
the less costly alternative does not
appear to achieve the objectives of the
LT2ESWTR.
The other alternatives considered by
the Agency achieve the objectives of the
rule, but are more costly, more
burdensome, and potentially less cost-
effective. The alternative in today's rule
targets additional treatment
requirements to PWSs with the highest
vulnerability to Cryptosporidium and
maximizes net benefits under a broad
range of conditions (USEPA 2005a).
Consequently, EPA has found the
alternative in today's rule to be the most
cost-effective among those that achieve
the objectives of the rule.
EPA has determined that this rule
contains no regulatory requirements that
might significantly or uniquely affect
small governments. Thus, today's rule is
not subject to the requirements of
section 203 of UMRA. As described in
section VII.C, EPA has certified that
today's rule will not have a significant
economic impact on a substantial
number of small entities. Average
annual expenditures for small PWSs to
comply with the LT2ESWTR range from
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757
$8.1 to $13.4 million at a 3% discount
rate and $8.3 to $13.5 million at a 7%
discount rate. While the treatment
requirements of the LT2ESWTR apply
uniformly to both small and large PWSs,
large PWSs bear a majority of the total
costs of compliance with the rule. This
is due to the fact that large PWSs treat
a majority of the drinking water that
originates from surface water sources.
E. Executive Order 13132: Federalism
Executive Order 13132, entitled
"Federalism" (64 FR 43255, August 10,
1999), requires EPA to develop an
accountable process to ensure
"meaningful and timely input by State
and local officials in the development of
regulatory policies that have federalism
implications." "Policies that have
federalism implications" is defined in
the Executive Order to include
regulations that have "substantial direct
effects on the States, on the relationship
between the national government and
the States, or on the distribution of
power and responsibilities among the
various levels of government."
Under Executive Order 13132, EPA
may not issue a regulation that has
federalism implications, that imposes
substantial direct compliance costs, and
that is not required by statute, unless
the Federal government provides the
funds necessary to pay the direct
compliance costs incurred by State and
local governments, or EPA consults with
State and local officials early in the
process of developing the regulation.
EPA has concluded that this final rule
ma}' have federalism implications,
because it may impose substantial direct
compliance costs on State or local
governments, and the Federal
government will not provide the funds
necessary to pay those costs. The final
rule may result in expenditures by State,
local, and Tribal governments, in the
aggregate of $100 million or more in any
one year. Costs are estimated to range
from $93 to $133 million at a 3 percent
discount rate and $107 to $150 million
using a 7 percent discount rate based on
the median distribution modeled from
ICRSSL and Information Collection Rule
Cryptosporidium occurrence data sets.
Accordingly, EPA provides the
following federalism summary impact
statement as required by section 6(b) of
Executive Order 13132.'
EPA consulted with representatives of
State and local officials early in the
process of developing today's rule to
permit them to have meaningful and
timely input into its development. As
described in the proposed rule (USEPA
2003a), this consultation included State
and local government representatives on
the Stage 2 M-DBP Federal Advisory
Committee (whose recommendations
were largely adopted in today's rule),
the representatives from small local
governments to the SBAR panel, a
meeting with representatives from the
Association of State Drinking Water
Administrators, the National Governors'
Association, the National Conference of
State Legislatures, the International
City/County Management Association,
the National League of Cities, the
County Executives of America, and
health departments, consultation with
Tribal governments at four meetings and
through the Advisory Committee
process, and comments from State and
local governments on a pre-proposal
draft of the LT2ESWTR.
Representatives of State and local
officials were generally concerned with
ensuring that drinking water regulations
are adequately protective of public
health and that any additional
regulations achieve significant health
benefits in return for required
expenditures. They were specifically
concerned with the burden of the rule,
both in cost and technical complexity,
giving flexibility to PWSs and States,
balancing the control of microbial risks
and DBF risks, funding for
implementing new regulations, equal
protection for small PWSs, and early
implementation of monitoring by large
PWSs.
EPA has concluded that the
LT2ESWTR is needed to reduce the
public health risk associated with
Cryptosporidium in drinking water. As
shown in section VI, estimated benefits
for the rule are significantly higher than
costs. Further, EPA believes that today's
rule addresses many of the concerns
expressed by representatives of
government officials.
Under the LT2ESWTR, expenditures
for additional treatment are targeted to
the fraction of PWSs with the highest
vulnerability to Cryptosporidium,
thereby minimizing burden for the
majority of PWSs, which will not be
required to provide additional
treatment. The microbial toolbox of
compliance options will provide
flexibility to PWSs in meeting
additional treatment requirements, and
States have the flexibility to award
treatment credits based on site-specific
demonstrations. Disinfection profiling
provisions are intended to ensure that
PWSs do not reduce microbial
protection as they take steps to reduce
exposures to DBFs.
The LT2ESWTR achieves equal public
health protection for small PWSs.
However, the use of E. coli monitoring
by small PWSs as a screening analysis
to determine the need for
Cryptosporidium monitoring will
reduce monitoring costs for most small
PWSs. Capital projects related to the
rule will be eligible for funding from the
Drinking Water State Revolving Fund,
which includes specific funding for
small communities. EPA is planning to
support the initial monitoring by large
PWSs that takes place within the first
few years after rule promulgation. This
will substantially reduce the burden on
States associated with early
implementation of monitoring
requirements.
In the spirit of Executive Order 13132,
and consistent with EPA policy to
promote communications between EPA
and State and local governments, EPA
specifically solicited comment on the
proposed rule from State and local
officials.
As required by section 8(a) of
Executive Order 13132, EPA included a
certification from its Federalism Official
stating that EPA had met the Executive
Order's requirements in a meaningful
and timely manner, when it sent the
draft of this final rule to OMB for review
pursuant to Executive Order 12866. A
copy of this certification has been
included in the public version of the
official record for this final rule.
F. Executive Order 13175: Consultation
and Coordination With Indian Tribal
Governments
Executive Order 13175, entitled
"Consultation and Coordination with
Indian Tribal Governments" (65 FR
67249, November 9, 2000), requires EPA
to develop "an accountable process to
ensure meaningful and timely input by
tribal officials in the development of
regulatory policies that have tribal
implications." Under Executive Order
13175, EPA may not issue a regulation
that has Tribal implications, that
imposes substantial direct compliance
costs, and that is not required by statute,
unless the Federal government provides
the funds necessary to pay the direct
compliance costs incurred by Tribal
governments, or EPA consults with
Tribal officials early in the process of
developing the proposed regulation and
develops a Tribal summary impact
statement.
EPA has concluded that this final rule
may have Tribal implications, because it
may impose substantial direct
compliance costs on Tribal
governments, and the Federal
government will not provide the funds
necessary to pay those costs. EPA has
identified 93 Tribal water systems
serving a total population of 82,216 that
may be subject to the LT2ESWTR. They
will bear an estimated total annualized
cost of $207,105 at a 3 percent discount
rate ($309,583 at 7 percent) to
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implement this rule. Estimated mean
annualized cost per system ranges from
$1,944 to $7,068 at a 3 percent discount
rate [$2,905 to $10,681 at 7 percent)
depending on PWS size (see Chapter 7
of the LT2ESWTR Economic Analysis
(USEPA 2005a) for details).
Accordingly, EPA provides the
following Tribal summary impact
statement as required by section 5(b).
EPA consulted with Tribal officials
early in the process of developing this
regulation to permit them to have
meaningful and timely input into its
development. This consultation is
described in the proposed rule (USEPA
2003a). Tribal officials were represented
on the M-DBP Advisory Committee.
As required by section 7(a), EPA's
Tribal Consultation Official has certified
that the requirements of the Executive
Order have been met in a meaningful
and timely manner. A copy of this
certification is included in the docket
for this rule.
G. Executive Order 13045: Protection of
Children From Environmental Health
and Safety Risks
Executive Order 13045: "Protection of
Children from Environmental Health
Risks and Safety Risks" (62 FR 19885,
April 23, 1997) applies to any rule that:
(1) is determined to be "economically
significant" as defined under Executive
Order 12866, and (2) concerns an
environmental health or safety risk that
EPA has reason to believe may have a
disproportionate effect on children. If
the regulatory action meets both criteria.
the Agency must evaluate the
environmental health or safety effects of
the planned rule on children and
explain why the planned regulation is
preferable to other potentially effective
and reasonably feasible alternatives
considered by the Agency.
This final rule is subject to the
Executive Order because it is an
economically significant regulatory
action as defined in Executive Order
12866, and we believe that the
environmental health or safety risk
addressed by this action may have a
disproportionate effect on children.
Accordingly, we have evaluated the
environmental health or safety effects of
Cryptosporidium on children. The
results of this evaluation are contained
in Cryptosporidium: Risk for Infants and
Children (USEPA 2001 d), which is
available in the public docket for this
action, and are summarized in this
section of the preamble. Further, while
available information is not adequate to
conduct a quantitative risk assessment
specifically for children, EPA has
assessed the risk associated with
Cryptosporidium in drinking water for
the general population, including
children. This assessment is described
in the Economic Analysis for the
LT2ESWTR (USEPA 2005a) and is
summarized in section VI of this
preamble.
Children's Environmental Health
Cryptosporidiosis in children is
similar to adult disease (USEPA 2001d).
Diarrhea is the most common symptom.
Other common symptoms in otherwise
healthy (i.e., immunocompetent)
children include anorexia, vomiting,
abdominal pain, fever, dehydration and
weight loss.
The risk of illness and death due to
Cryptosporidiosis depends on several
factors, including age, nutrition,
exposure, genetic variability, disease
and the immune status of the
individual. Mortality resulting from
diarrhea generally occurs at a greater
rate among the very young and elderly
(Gerba et al., 1996)'. During the 1993
Milwaukee drinking water outbreak.
associated mortalities in children were
reported. Also, children with laboratory-
confirmed Cryptosporidiosis were more
likely to have an underlying disease that
altered their immune status (Cicirello et
al., 1997). In that study, the observed
association between increasing age of
children and increased numbers of
laboratory-confirmed Cryptosporidiosis
suggested to the authors that the data
are consistent with increased tap water
consumption of older children.
Asymptomatic infection can have a
substantial effect on childhood growth
(Bern et al., 2002).
Cryptosporidiosis appears to be more
prevalent in populations, such as
children, that may not have established
immunity against the disease and may
be in greater contact with
environmentally contaminated surfaces
(DuPont et al.. 1995). In the United
States, children aged one to four years
are more likely than adults to have the
disease. The most recent reported data
on Cryptosporidiosis shows the
occurrence rate (for the year 1999) is
higher in children ages one to four (3.03
incidence rate per 100,000) than in any
adult age group (CDC, 2001). Evidence
from blood sera antibodies collected
from children during the 1993
Milwaukee outbreak suggest that
children had greater levels of
Cryptosporidium infection than
predicted for the general community
(based on the random-digit dialing
telephone survey method) (McDonald et
al., 2001).
Data indicate a lower incidence of
Cryptosporidiosis infection during the
first year of life. This is attributed to
breast-fed infants consuming less tap
water and, hence, having less exposure
to Cryptosporidium, as well as the
possibility that mothers confer short
term immunity to their children. For
example, in a survey of over 30,000
stool sample analyses from different
patients in the United Kingdom, the one
to five year age group suffered a much
higher infection rate than individuals
less than one year of age. For children
under one year of age, those older than
six months of age showed a higher rate
of infection than individuals aged less
than six months (Casemore, 1990).
Similarly, in the U.S., of 2,566 reported
Cryptosporidium illnesses in 1999, 525
occurred in ages one to four (incidence
rate of 3.03 per 100,000) compared with
58 cases in infants under one year
(incidence rate of 1.42 per 100,000)
(CDC. 2001).
An infected child may spread the
disease to other children or family
members (Heijbel et al., 1987, Osewe et
al., 1996). Millard et al. (1994)
documented greater household
secondary transmission of
Cryptosporidiosis from children than
from adults to household and other
close contacts. Children continued to
shed oocysts for more than two weeks
(mean 16.5 days) after diarrhea
cessation (Tangerman et al., 1991).
While Cryptosporidium may have a
disproportionate effect on children,
available data are not adequate to
distinctly assess the health risk for
children resulting from
Cryptosporidium-contaminated
drinking water. In assessing risk to
children when evaluating regulatory
alternatives for the LT2ESWTR, EPA
assumed the same risk for children as
for the population as a whole.
Section VI of this preamble presents
the regulatory alternatives that EPA
evaluated for the proposed LT2ESWTR.
Among the four alternatives the Agency
considered, three involved a risk-
targeting approach in which additional
Cryptosporidium treatment
requirements are based on source water
monitoring results. A fourth alternative
involved additional treatment
requirements for all PWSs. The
alternative requiring additional
treatment by all PWSs was not selected
because of concerns about feasibility
and because it imposed costs but
provided few benefits to PWSs with
high quality source water (i.e., relatively
low Cryptosporidium risk). The three
risk-targeting alternatives were
evaluated based on several factors,
including costs, benefits, net benefits,
feasibility of implementation, and other
specific impacts (e.g., impacts on small
PWSs or sensitive subpopulations).
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759
The alternative that today's final rule
establishes was recommended by the
M-DBP Federal Advisory Committee
and selected by EPA as the Preferred
Regulatory Alternative because it was
deemed feasible and provides
significant public health benefits in
terms of avoided illnesses and deaths.
EPA's analysis of benefits and costs
indicates that this alternative ranks
highly among those evaluated with
respect to maximizing net benefits, as
shown in the LT2ESWTR Economic
Analysis (USEPA 2005a). This
document is available in the docket for
this action.
The result of the LT2ESWTR will be
a reduction in the risk of illness for the
entire population, including children.
Because available evidence indicates
that children may be more vulnerable to
cryptosporidiosis than the rest of the
population, the LT2ESWTR may,
therefore, result in greater risk reduction
for children than for the general
population.
H. Executive Order 13211: Actions That
Significantly Affect Energy Supply,
Distribution, or Use
This rule is not a "significant energy
action" as defined in Executive Order
13211, "Actions Concerning Regulations
That Significantly Affect Energy Supply,
Distribution, or Use" (66 FR 28355 (May
22, 2001)) because it is not likely to
have a significant adverse effect on the
supply, distribution, or use of energy.
This determination is based on the
following analysis.
The first consideration is whether the
LT2ESWTR would adversely affect the
supply of energy. The LT2ESWTR does
not regulate power generation, either
directly or indirectly. The public and
private utilities that the LT2ESWTR
regulates do not, as a rule, generate
power. Further, the cost increases borne
by customers of water utilities as a
result of the LT2ESWTR are a low
percentage of the total cost of water,
except for a very few small PWSs that
might install advanced technologies and
then need to spread that cost over a
narrow customer base. Therefore, the
customers that are power generation
utilities are unlikely to face any
significant effects as a result of the
LT2ESWTR. In sum, the LT2ESWTR
does not regulate the supply of energy,
does not generally regulate the utilities
that supply energy, and is unlikely to
affect significantly the customer base of
energy suppliers."Thus, the LT2ESWTR
would not translate into adverse effects
on the supply of energy.
The second consideration is whether
the LT2ESWTR would adversely affect
the distribution of energy. The
LT2ESWTR does not regulate any aspect
of energy distribution. The utilities that
are regulated by the LT2ESWTR already
have electrical service. As derived later
in this section, the final rule is projected
to increase peak electricity demand at
water utilities by only 0.036 percent.
Therefore, EPA estimates that the
existing connections are adequate and
that the LT2ESWTR has no discernable
adverse effect on energy distribution.
The third consideration is whether
the LT2ESWTR would adversely affect
the use of energy. Because some
drinking water utilities are expected to
add treatment technologies that use
electrical power, this potential impact is
evaluated in more detail. The analyses
that underlay the estimation of costs for
the LT2ESWTR are national in scope
and do not identify specific plants or
utilities that may install treatment in
response to the rule. As a result, no
analysis of the effect on specific energy
suppliers is possible with the available
data. The approach used to estimate the
impact of energy use, therefore, focuses
on national-level impacts. The analysis
estimates the additional energy use due
to the LT2ESWTR, and compares that to
the national levels of power generation
in terms of average and peak loads.
The first step in the analysis is to
estimate the energy used by the
technologies expected to be installed as
a result of the LT2ESWTR. Energy use
is not directly stated in Technologies
and Costs for Control of Microbial
Contaminants and Disinfection By-
Products (USEPA 2003c), but the annual
cost of energy for each technology
addition or upgrade necessitated by the
LT2ESWTR is provided. An estimate of
plant-level energy use is derived by
dividing the total energy cost per plant
for a range of flows by an average
national cost of electricity of $0.070/
kWh (USDOE 2004a). These
calculations are shown in detail in
Chapter 7 of the Economic Analysis for
the LT2ESWTR (USEPA 2005a)."The
energy use per plant for each flow range
and technology is then multiplied by
the number of plants predicted to install
each technology in a given flow range.
The energy requirements for each flow
range are then added to produce a
national total. No electricity use is
subtracted to account for the
technologies that may be replaced by
new technologies, resulting in a
conservative estimate of the increase in
energy use. Results of the analysis are
shown in Table VII.H-l for each of the
modeled Cryptosporidium occurrence
distributions. The incremental national
annual energy usage is estimated at 165
million megawatt-hours (mW) based on
the modeled Information Collection
Rule occurrence distribution.
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
Table VII.H-1.- Total Increased Annual National Energy Usage Attributable to the
LT2ESWTR
Technology
UV
03 (0.5 log)
03 (1.0 log)
O3 (2.0 log)
ME/UF
Bag Filters
Cartridge Filters
Total
Plants Selecting
Technology
A
1,038
27
18
14
37
1,523
209
2,867
Total Annual
Energy Required
(kWh/yr)
B
100,829,791
20,617,993
18,827,749
16,245,643
7,343,320
1,605,380
82,022
165,551,898
Source: The LT2ESWTR Economic Arah5/5 (USEPA 2005a)
To determine if the additional energy
required for PWSs to comply with the
rule would have a significant adverse
effect on the use of energy, the numbers
in Table VII.H-1 are compared to the
national production figures for
electricity. According to the U.S.
Department of Energy's Information
Administration, electricity producers
generated 3,848 million mW of
electricity in 2003 (USDOE 2004b).
Therefore, even using the highest
assumed energy use for the LT2ESWTR,
the rule when fully implemented would
result in only a 0.004 percent increase
in annual average energy use.
In addition to average energy use, the
impact at times of peak power demand
is important. To examine whether
increased energy usage might
significantly affect the capacity margins
of energy suppliers, their peak season
generating capacity reserve was
compared to an estimate of peak
incremental power demand by water
utilities.
Both energy use and water use are
highest in the summer months, so the
most significant effects on supply would
be seen then. In the year of 2003, U.S.
generation capacity exceeded
consumption by 15 percent, or
approximately 160,00 mW (USDOE EIA
2004b). Assuming around-the-clock
operation of water treatment plants, the
total energy requirement can be divided
by 8,760 hours per year to obtain an
average power demand of 19 mW for the
modeled Information Collection Rule
occurrence distribution. A more
detailed derivation of this value is
shown in Chapter 7 of the Economic
Analysis for the LT2ESWTR (USEPA
2005a). Assuming that power demand is
proportional to water flow through the
plant, and that peak flow can be as high
as twice the average daily flow during
the summer months, about 38 mW
could be needed for treatment
technologies installed to comply with
the LT2ESWTR. This is only 0.024
percent of the capacity margin available
at peak use.
Although EPA recognizes that not all
areas have a 15 percent capacity margin
and that this margin varies across
regions and through time, this analysis
reflects the effect of the rule on national
energy supply, distribution, or use.
While certain areas, notably California,
have experienced shortfalls in
generating capacity in the recent past, a
peak incremental power requirement of
38 mW nationwide is not likely to
significantly change the energy supply,
distribution, or use in any given area.
Considering this analysis. EPA has
concluded that LT2ESWTR is not likely
to have a significant adverse effect on
the supply, distribution, or use of
energy.
/. National Technology Transfer and
Advancement Act
As noted in the proposed rule.
Section 12(d) of the National
Technology Transfer and Advancement
Act ("NTTAA") of 1995, Public Law
104-113, section 12(d) (15 U.S.C. 272
note) directs EPA to use voluntary
consensus standards in its regulatory
activities unless to do so would be
inconsistent with applicable law or
otherwise impractical. Voluntary
consensus standards are technical
standards (e.g., materials specifications,
test methods, sampling procedures, and
business practices) that are developed or
adopted by voluntary consensus
standard bodies. The NTTAA directs
EPA to provide Congress, through OMB.
explanations when the Agency decides
not to use available and applicable
voluntary consensus standards.
This rulemaking involves technical
standards. EPA has decided to use
methods previously approved in 40 CFR
136.3 for the analysis of E. coli in
surface waters. These include several
voluntary consensus methods that were
developed or adopted by the following
organizations: American Public Health
Association in Standard Methods for the
Examination of Water and Wastewater,
20th. 19th, and 18th Editions, the
American Society of Testing Materials
in Annual Book of ASTM Standards—
Water and Environmental Technology.
and the Association of Analytical
Chemists in Official Methods of
Analysis of AOAC International, 16th
Edition. EPA has concluded that these
methods have the necessary sensitivity
and specificity to meet the data quality
objectives of the LT2ESWTR.
The Agency conducted a search to
identify potentially applicable voluntary
consensus standards for analysis of
Cryptosporidium. However, we
identified no such standards. Therefore,
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761
EPA approves the use of the following
methods for Cryptosporidium analysis:
Method 1623: Cryptosporidium and
Giardia in Water "by Filtration/IMS/FA,
2004, United States Environmental
Protection Agency, EPA-815-R-05-002
or Method 1622: Cryptosporidium in
Water by Filtration/IMS/FA, 2004,
United States Environmental Protection
Agency, EPA-815-R-05-001.
/. Executive Order 12898: Federal
Actions To Address Environmental
Justice in Minority Populations or Low-
Income Populations
Executive Order 12898 establishes a
Federal policy for incorporating
environmental justice into Federal
agency missions by directing agencies to
identify and address disproportionately
high and adverse human health or
environmental effects of its programs,
policies, and activities on minority and
low-income populations. EPA has
considered environmental justice
related issues concerning the potential
impacts of this action and consulted
with minority and low-income
stakeholders. A description of this
consultation can be found in the
proposed rule (USEPA 2003a).
K. Consultations With the Science
Advisory Board, National Drinking
Water Advisory Council, and the
Secretary of Health and Human Services
In accordance with Section 1412 (d)
and (e) of the SDWA, the Agency did
consult with the Science Advisory
Board, the National Drinking Water
Advisory Council (NOWAC), and the
Secretary of Health and Human Services
on today's rule.
EPA charged the SAB panel with
reviewing the following aspects of the
LT2ESWTR proposal:
• The analysis of Cryptosporidium
occurrence;
• The pre- and post-LT2ESWTR
Cryptosporidium risk assessment; and
• The treatment credits for the
following four microbial toolbox
components: raw water off-stream
storage, pre-sedimentation, lime
softening, and lower finished water
turbidity.
EPA met with the SAB to discuss the
LT2ESWTR on June 13, 2001
(Washington, DC), September 25-26,
2001 (teleconference), and December
10-12, 2001 (Los Angeles, CA). The
SAB issued its final report for this
review, Disinfection Byproducts and
Surface Water Treatment: A EPA
Science Advisory Board Review of
Certain Elements of the Stage 2
Regulatory Proposals, in May 2003.
Comments from the SAB were
generally supportive of EPA's analysis
of Cryptosporidium occurrence and the
Cryptosporidium risk assessment for
today's rule. The SAB recommended
some additional quality assurance
checks for statistical models, improved
descriptions of underlying data sets, and
better characterization of uncertainty for
key parameters. USEPA 2005a and
2005b provide information on revisions
EPA made in response to these
comments.
SAB comments on microbial toolbox
options and the Agency's responses to
those comments are described in section
IIII.D of this preamble. In general, the
SAB supported treatment credit for two-
stage softening, recommended
additional performance criteria to award
treatment credit to presedimentation
basins, recommended modifications to
the treatment credit for combined and
individual filter performance, and
opposed treatment credit for off-stream
raw water storage.
EPA met with the NDWAC on
November 8, 2001, in Washington, DC,
to discuss the LT2ESWTR proposal.
EPA specifically requested comments
from the NDWAC on the regulatory
approach taken in the proposed
microbial toolbox (e.g., proposal of
specific design and implementation
criteria for treatment credits). The
Council was generally supportive of
EPA establishing criteria for awarding
treatment credit to toolbox components,
but recommended that EPA provide
flexibility for States to address PWS
specific situations. EPA believes that the
demonstration of performance credit,
described in section IV.D.9 provides this
flexibility by allowing States to award
higher or lower levels of treatment
credit for microbial toolbox components
based on site specific conditions.
EPA has consulted with the U.S.
Department of Health and Human
Services (HHS) regarding
Cryptosporidium health effects and has
provided HHS with today's rule.
L. Plain Language
Executive Order 12866 requires each
agency to write its rules in plain
language. Readable regulations help the
public find requirements quickly and
understand them easily. They increase
compliance, strengthen enforcement,
and decrease mistakes, frustration,
phone calls, appeals, and distrust of
government. EPA made every effort to
write this preamble to the final rule in
as clear, concise, and unambiguous
manner as possible.
M. Analysis of the Likely Effect of
Compliance With the LT2ESWTR on the
Technical, Financial, and Managerial
Capacity of Public Water Systems
Section 1420(d)(3) of SDWA, as
amended, requires that in promulgating
an NPDWR, the Administrator shall
include an analysis of the likely effect
of compliance with the regulation on
the technical, managerial, and financial
capacity of public water systems. This
analysis can be found in the LT2ESWTR
Economic Analysis (USEPA 2005a).
Analyses reflect only the impact of new
or revised requirements, as established
by the LT2ESWTR; the impacts of
previously established requirements on
system capacity are not considered.
EPA has defined overall water system
capacity as the ability to plan for,
achieve, and maintain compliance with
applicable drinking water standards.
Capacity encompasses three
components: technical, managerial, and
financial. Technical capacity is the
physical and operational ability of a
water system to meet SDWA
requirements. This refers to the physical
infrastructure of the water system,
including the adequacy of source water
and the adequacy of treatment, storage.
and distribution infrastructure. It also
refers to the ability of system personnel
to adequately operate and maintain the
system and to otherwise implement
requisite technical knowledge.
Managerial capacity is the ability of a
water system to conduct its affairs to
achieve and maintain compliance with
SDWA requirements. Managerial
capacity refers to the system's
institutional and administrative
capabilities. Financial capacity is a
water system's ability to acquire and
manage sufficient financial resources to
allow the system to achieve and
maintain compliance with SDWA
requirements. Technical, managerial,
and financial capacity can be assessed
through key issues and questions,
including the following:
Technical Capacity
Source water adequacy
Does the system have a reliable source of water with adequate quantity? Is the source generally of good
quality and adequately protected?
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
Infrastructure adequacy
Technical knowledge and imple-
mentation
Can the system provide water that meets SDWA standards9 What is the condition of its infrastructure, in-
cluding wells or source water intakes, treatment and storage facilities, and distribution systems? What is
the infrastructure's life expectancy9 Does the system have a capital improvement plan?
Are the system's operators certified9 Do the operators have sufficient knowledge of applicable standards7
Can the operators effectively implement this technical knowledge9 Do the operators understand the sys-
tem's technical and operational characteristics9 Does the system have an effective O&M program9
Managerial Capacity
Ownership accountability
Staffing and organization
Effective external linkages
Are the owners clearly identified9 Can they be held accountable for the system9
Are the operators and managers clearly identified9 is the system properly organized and staffed9 Do per-
sonnel understand the management aspects of regulatory requirements and system operations' Do they
have adequate expertise to manage water system operations (i.e., to conduct implementation, monitor
for E coli and Cryptospondium, install treatment, and cover or disinfect reservoir discharge to meet the
LT2ESWTR requirements)9 Do personnel have the necessary licenses and certifications9
Does the system interact well with customers, regulators, and other entities? Is the system aware of avail-
able external resources, such as technical and financial assistance9
Financial Capacity
Revenue sufficiency
Creditworthiness
Fiscal management and controls
Do revenues cover costs9
Is the system financially healthy9 Does it have access to capital through public or private sources9
Are adequate books and records maintained9 Are appropriate budgeting, accounting, and financial plan-
ning methods used9 Does the system manage its revenues effectively9
After determining the type and
number of systems to which each
requirement applies, EPA evaluated the
capacity impact of each rule
requirement on large and small systems
affected by that particular requirement.
EPA determined that the overall impacts
on small systems' technical, managerial,
and financial capacity will vary.
Monitoring and familiarization with
new rules will have no significant
effects on small systems, with the
exception of moderate revenue
constraints on those systems that need
to implement monitoring for
Cryptosporidium. The largest impacts
will occur as a result of attaining 2.5 log
treatment levels, covering uncovered
reservoirs, or disinfecting reservoir
discharge. EPA assumed that large
systems will have the technical,
financial, and managerial capacity to
implement LT2ESWTR requirements
based on the scale and complexity of
their operations. The nature of their
operations generally assures that they
have access to the technical and
managerial expertise to carry out all
activities required by the LT2ESWTR. It
is also generally easier for large systems
to fund capital improvements than
small systems, since costs can be spread
over a larger customer base, making
them smaller on a per-household basis.
To meet challenges posed by rule
requirements, it is likely that some
small and medium systems will need to
develop or enhance linkages with
technical and financial assistance
providers (including State extension
agents). Technical and financial
assistance providers can help systems
analyze their needs as well as the trade-
offs between cost and health protection.
In addition, they may be able to assist
systems in finding the funding
necessary to install and operate new
equipment. The Safe Drinking Water
Act, as amended in 1996. established
the Drinking Water State Revolving
Fund to make funds available to
drinking water systems to finance
infrastructure improvements. EPA also
works closely with organizations such
as the National Rural Water Association
and the American Water Works
Association to develop technical and
managerial tools, materials, and
assistance to aid small systems.
N. Congressional Review Act
The Congressional Review Act. 5
U.S.C. 801 et seq., as added by the Small
Business Regulatory Enforcement
Fairness Act of 1996, generally provides
that before a rule may take effect, the
agency promulgating the rule must
submit a rule report, which includes a
copy of the rule, to each House of the
Congress and to the Comptroller General
of the United States. EPA will submit a
report containing this rule and other
required information to the U.S. Senate,
the U.S. House of Representatives, and
the Comptroller General of the United
States prior to publication of the rule in
the Federal Register. A Major rule
cannot take effect until 60 days after it
is published in the Federal Register.
This action is a "major rule'' as defined
by 5 U.S.C. 804(2). This rule will be
effective March 6, 2006.
VIII. References
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Arora. H., M. LeChevallier. R. Aboytes. E
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Protection Agency. Guidelines for
Preparing Economic Analyses
Washington. DC. EPA 240-R-00-003.
September 2000.
USEPA. 2000cl SAB Report from the
Environmental Economics Advisory
Committee on EPA's White Paper
"Valuing the Benefits of Fatal Cancer
Risk Reduction." EPA-SAB-EEAC-00-
013.
USEPA. 2001a. National Primary Drinking
Water; Filter Backwash Recycling Rule.
Final Rule. 66 FR 31086: June 8. 2001.
EPA-815-Z-01-001.
USEPA. 2001 b. Cryptosporidium- Human
Health Criteria Document. EPA-822-K-
94-001.
USEPA 2001 c. Cryptosporidium: Drinking
Water Advisory. EPA-822-R-01-009
USEPA. 200ld Cryptosporidium: Risk for
Infants and Children. February 23. 2001.
USEPA. 2001e. Method 1622'
"Cryptosporidium in Water by
Filtration/IMS/FA" EPA-821-R-01-026.
April 2001.
USEPA. 200lf. Method 1623:
"Cryptosporidium and Giardia in Water
by Filtration/IMS/FA" EPA 821-R-01-
025. April 2001.
USEPA. 2001g. Low-Pressure Membrane
Filtration for Pathogen Removal:
Application, Implementation and
Regulatory Issues. EPA 815-C-01-001.
USEPA. 200lh. Guidelines Establishing Test
Procedures ior_the Analysis of
Pollutants; Analytical Methods for
Biological Pollutants in Ambient Water;
Proposed Rule. Federal Register. August
30,2001
USEPA. 2002a. National Primary Drinking
Water Regulations: Long Term 1
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
767
Enhanced Surface Water Treatment Rule;
Final Rule. Federal Register. January 14,
2002. 67 FR 1812. EPA 815-Z-02-001.
USEPA. 2002b. Process for Designing a
Watershed Initiative. 67 FR 36172. May
23,2002.
USEPA. 2002c. Method 1103.1: Escherichia
coh (E. coli) In Water By Membrane
Filtration Using membrane-
Thermotolerant Escherichia coli Agar
(mTEC). U.S. Environmental Protection
Agency, Office of Water, Washington,
DC. EPA-821-R-02-020.
USEPA. 2002d. Laboratory Quality
Assurance Evaluation Program for
Analysis of Cryptosporidium Under the
Safe Drinking Water Act; Agency
Information Collection: Proposed
Collection; Comment Request. Federal
Register: March 4, 2002. 67 FR 9731.
USEPA. 2003a. National Primary Drinking
Water Regulations: Long Term 2
Enhanced Surface Water Treatment Rule;
Proposed Rule. 68 FR 47640, August 11,
2003.
USEPA. 2003b. Guidelines Establishing Test
Procedures for the Analysis of
Pollutants; Analytical Methods for
Biological Pollutants in Ambient Water.
68 FR 43272, July 21, 2003.
USEPA. 2005a. Economic Analysis for the
Long Term 2 Enhanced Surface Water
Treatment Rule. U.S. Environmental
Protection Agency, Office of Water,
Washington. DC. EPA-821-R-06-001.
USEPA. 2005b. Occurrence and Exposure
Assessment for the Long Term 2
Enhanced Surface Water Treatment Rule.
U.S. Environmental Protection Agency,
Office of Water. Washington, DC. EPA-
821-R-06-002
USEPA. 2005c. Method 1622:
Cryptosporidium in Water by Filtration/
IMS/FA. EPA 815-R-05-OOi.
USEPA. 2005d. Method 1623-
Cryptosporidium and Giardia in Water
by>iltration/IMS/FA. EPA 815-R-05-
002.
USEPA. 2005e. Valuing Time Losses Duo to
Illness under tho 1996 Amendments to
the Safe Drinking Water Act. EPA Office
of Water. Prepared by IEC Consultants.
Wang. ]., R. Song, and S. Hubbs 2001.
Particle removal through riverbank
filtration process, in W. Julich and J.
Schubert, eds., Proceedings of the
Internation Riverbank Filtration
Conference. November 2-4, 2000,
Dusseldorf. Germany, Internationale
Arbeitsgemeinschaft der Wasserwork im
Rheineinzugsgebiet.
Ware and Schaefer. 2005 The effects of time
and temperature on flow cytometry
enumerated live Cryptosporidium
parvum oocysts. Letters in Applied
Microbiology 41:385-389.
Yang, S., S.K. Benson. C. Du, and M.C.
Healey. 2000. Infection of
immunosuppressed C57BL/6N adult
mice with a single oocyst of
Cryptosporidium parvum. ] Parasitol.
86(4):884-7.
Yates. R., K. Scott, J. Green. |. Bruno, and R.
De Leon. 1998. Using Aerobic Spores to
Evaluate Treatment Plant Performance.
Proceedings, Annual Conference of the
American Water Works Association,
Denver, CO.
List of Subjects
40 CFR Part 9
Reporting and recordkeeping.
40 CFR Part 141
Environmental protection, Chemicals,
Indians-lands, Incorporation by
reference, Intergovernmental relations,
Radiation protection, Reporting and
recordkeeping requirements, Water
supply.
40 CFR Part 142
Environmental protection.
Administrative practice and procedure,
Chemicals, Indians-lands. Radiation
protection, Reporting and recordkeeping
requirements, Water supply.
Dated: December 15. 2005.
Stephen L. Johnson,
Administrator.
• For the reasons set forth in the
preamble, title 40 chapter I of the Code
of Federal Regulations is amended as
follows:
PART 9—[AMENDED]
• 1. The authority citation for part 9
continues to read as follows:
Authority: 7 U.S.C. 135 et seq.. 136-136y;
15 U.S.C. 2001, 2003. 2005, 2006, 2601-2671;
21 U.S.C. 331j, 346a, 348; 31 U.S.C. 9701; 33
U.S.C. 1251 et seq.. 1311, 1313d, 1314. 1318,
1321.1326, 1330, 1342, 1344. 1345 (d) and
(e), 1361; Executive Order 11735, 38 FR
21243, 3 CFR, 1971-1975 Comp. p. 973: 42
U.S.C. 241, 242b, 243, 246. 300f, 300g, 300g-
1. 300g-2. 300g-3. 300g-4, 300g-5. 300g-6,
300J-1, 300J-2, 300J-3. 300J-4, 300J-9. 1857
et seq.. 6901-6992k, 7401-7671q. 7542,
9601-9657, 11023. 11048.
• 2. In § 9.1 the table is amended as
follows:
• a. Under the heading "National
Primary Drinking Water Regulations
Implementation" by adding entries in
numerical order for "§ 141.706-141.710,
141.713-141.714, 141.716-141.723".
• b. Under the heading "National
Primary Drinking Water Regulations
Implementation" by removing entries
§142.15(c), 142.15(c)(6)-(7) and adding
entries in numerical order for
"142.14(a)(9), 142.15(c)(6), and
142.16(n)" as follows:
§9.1 OMB approvals under the Paperwork
Reduction Act.
40 CFR citation
OMB control No.
National Primary Drinking Water Regulations
141.706-141.710
141.713-141.714
141 716-141.723
2040-0266
2040-0266
2040-0266
National Primary Drinking Water Regulations Implementation
142.14(a)(9)
142.15(c)(6)
142.16(n)
2040-0266
2040-0266
2040-0266
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Federal Register/ Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
PART 141—NATIONAL PRIMARY
DRINKING WATER REGULATIONS
• 3. The authority citation for Part 141
continues to read as follows:
Authority: 42 U.S.C. 300f. 300g-l, 300g-2,
300g-3, 300g-4, 300g-5. 300g-6. 300J-4,
300J-9. andSOOj-ll.
• 4. Section 141.2 is amended by
adding, in alphabetical order,
definitions for "Bag filters", "Bank
filtration", "Cartridge filters", "Flowing
stream", "Lake/reservoir", "Membrane
filtration", "Plant intake",
"Presedimentation", and "Two-stage
lime softening", and revising the
definition for "Uncovered finished
water storage facility" to read as
follows:
§141.2 Definitions.
*****
Bag filters are pressure-driven
separation devices that remove
particulate matter larger than 1
micrometer using an engineered porous
filtration media. They are typically
constructed of a non-rigid, fabric
filtration media housed in a pressure
vessel in which the direction of flow is
from the inside of the bag to outside.
Bank filtration is a water treatment
process that uses a well to recover
surface water that has naturally
infiltrated into ground water through a
river bed or bank(s). Infiltration is
typically enhanced bv the hydraulic
gradient imposed by a nearby pumping
water supply or other well(s).
*****
Cartridge filters are pressure-driven
separation devices that remove
particulate matter larger than 1
micrometer using an engineered porous
filtration media. They are typically
constructed as rigid or semi-rigid, self-
supporting filter elements housed in
pressure vessels in which flow is from
the outside of the cartridge to the inside.
*****
Flowing stream is a course of running
water flowing in a definite channel.
*****
Lake/reservoir refers to a natural or
man made basin or hollow on the
Earth's surface in which water collects
or is stored that may or may not have
a current or single direction of flow.
*****
Membrane filtration is a pressure or
vacuum driven separation process in
which particulate matter larger than 1
micrometer is rejected by an engineered
barrier, primarily through a size-
exclusion mechanism, and which has a
measurable removal efficiency of a
target organism that can be verified
through the application of a direct
integrity test. This definition includes
the common membrane technologies of
microfiltration, ultrafiltration,
nanofiltration, and reverse osmosis.
*****
Plant intake refers to the works or
structures at the head of a conduit
through which water is diverted from a
source (e.g., river or lake) into the
treatment plant.
*****
Presedimentation is a preliminary
treatment process used to remove
gravel, sand and other particulate
material from the source water through
settling before the water enters the
primary clarification and filtration
processes in a treatment plant.
*****
Two-stage lime softening is a process
in which chemical addition and
hardness precipitation occur in each of
two distinct unit clarification processes
in series prior to filtration.
Uncovered finished water storage
facility is a tank, reservoir, or other
facility used to store water that will
undergo no further treatment to reduce
microbial pathogens except residual
disinfection and is directly open to the
atmosphere.
*****
• 5. Subpart Q of part 141 is amended
by adding § 141.211 to read as follows:
§ 141.211 Special notice for repeated
failure to conduct monitoring of the source
water for Cryptosporidium and for failure to
determine bin classification or mean
Cryptosporidium level.
(a) When is the special notice for
repeated failure to monitor to be given?
The owner or operator of a community
or non-community water system that is
required to monitor source water under
§ 141.701 must notify persons served by
the water system that monitoring has
not been completed as specified no later
than 30 days after the system has failed
to collect any 3 months of monitoring as
specified in § 141.701(c). The notice
must be repeated as specified in
§141.203 (b).
(b) When is the special notice for
failure to determine bin classification or
mean Cryptosporidium level to be
given? The owner or operator of a
community or non-community water
system that is required to determine a
bin classification under § 141.710, or to
determine mean Cryptosporidium level
under § 141.712, must notify persons
served by the water system that the
determination has not been made as
required no later than 30 days after the
system has failed report the
determination as specified in
§ 141.710(e) or § 141.712(a),
respectively. The notice must be
repeated as specified in § 141.203(b).
The notice is not required if the system
is complying with a State-approved
schedule to address the violation.
(c) What is the form and manner of
the special notice? The form and
manner of the public notice must follow
the requirements for a Tier 2 public
notice prescribed in § 141.203(c). The
public notice must be presented as
required in § 141.205(c).
(d) What mandatory language must be
contained in the special notice? The
notice must contain the following
language, including the language
necessary to fill in the blanks.
(1) The special notice for repeated
failure to conduct monitoring must
contain the following language:
We are required to monitor the source of
your drinking water for Crvptosporidium
Results of the monitoring are to be used to
determine whether water treatment at the
[treatment plant name) is sufficient to
adequately remove Crvptosporidium from
your drinking water. We are required to
complete this monitoring and make this
determination by (required bin determination
date). We "did not monitor or test" or "did
not complete all monitoring or testing" on
schedule and. therefore, we may not be ablo
to determine by the required date what
treatment modifications, if any. must be
made to ensure adequate Crvptosporidium
removal. Missing this deadline mav. in turn.
jeopardize our ability to have the required
treatment modifications if any, completed b\
the deadline required, (date)
For more information, please call (name of
water system contact) of (name of water
system) at (phone number)
(2) The special notice for failure to
determine bin classification or mean
Cryptosporidium level must contain the
following language:
We are required to monitor the source of
your drinking water for Cryptosporidium in
order to determine by (date) whether water
treatment at the (treatment plant name) is
sufficient to adequately remove
Cryptosporidium from your drinking water.
We have not made this determination by the
required date. Our failure to do this may
jeopardize our ability to have the required
treatment modifications, if any. completed by
the required deadline of (date). For more
information, please call (name of water
system contact) of (name of water system) at
(phone number).
(3) Each special notice must also
include a description of what the system
is doing to correct the violation and
when the system expects to return to
compliance or resolve the situation.
• 6. Appendix A to Subpart Q of part
141 is amended by adding entry number
10 under LA. to read as follows:
Subpart Q—Public Notification of
Drinking Water Violations
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
769
APPENDIX A TO SUBPART Q OF PART 141—NPDWR VIOLATIONS AND OTHER SITUATIONS REQUIRING PUBLIC NOTICE"
Contaminant
MCL/MRDLATT violations2
Tier of
public notice Citation
required
Monitoring & testing procedure violations
Tier of
public notice Citation
required
I Violations of National Primary Drinking
Water Regulations (NPDWR).3
A. Microbiological Contaminants
10. LT2ESWTR violations
2 141.710-141.720
222, 3 141 701-141.705 and 141.708-141.709.
1 Violations and other situations not listed in this table (e.g , failure to prepare Consumer Confidence Reports) do not require notice, unless
otherwise determined by the primary agency. Primacy agencies may, at their option, also require a more stringent public notice tier (e.g., Tier 1
instead of Tier 2 or Tier 2 instead of Tier 3) for specific violations and situations listed in this Appendix, as authorized under §141.202(a) and
§141.203(a).
2MCL—Maximum contaminant level, MRDL—Maximum residual disinfectant level, TT—Treatment technique.
3The term Violations of National Primary Drinking Water Regulations (NPDWR) is used here to include violations of MCL, MRDL, treatment
technique, monitoring, and testing procedure requirements.
22 Failure to collect three or more samples for Cryptosporidium analysis is a Tier 2 violation requiring special notice as specified in §141.211
All other monitoring and testing procedure violations are Tier 3.
• 7. Part 141 is amended by adding a
new subpart W to read as follows:
Subpart W—Enhanced Treatment for
Cryptosporidium
General Requirements
Sec.
141.700 General requirements
Source Water Monitoring Requirements
141.701 Source water monitoring.
141.702 Sampling schedules.
141.703 Sampling locations.
141.704 Analytical methods.
141.705 Approved laboratories.
141.706 Reporting source water monitoring
results.
141.707 Grandfathering previously
collected data.
Disinfection Profiling and Benchmarking
Requirements
141.708 Requirements when making a
significant change in disinfection
practice.
141.709 Developing the disinfection profiJe
and benchmark.
Treatment Technique Requirements
141.710 Bin classification for filtered
systems.
141.711 Filtered system additional
Cryptosporidium treatment
requirements.
141.712 Unfiltered system Cryptosporidium
treatment requirements.
141.713 Schedule for compliance with
Cryptosporidium treatment
requirements.
141.714 Requirements for uncovered
finished water storage facilities
Requirements for Microbial Toolbox
Components
141.715 Microbial toolbox options for
meeting Crvptosporidium treatment
requirements
141.716 Source toolbox components.
141.717 Pre-filtration treatment toolbox
components.
141.718 Treatment performance toolbox
components.
141.719 Additional filtration toolbox
components.
141.720 Inactivation toolbox components.
Reporting and Recordkeeping Requirements
141.721 Reporting requirements.
141.722 Recordkeeping requirements.
Requirements for Sanitary Surveys
Performed by EPA
141.723 Requirements to respond to
significant deficiencies identified in
sanitary surveys performed by EPA.
Subpart W—Enhanced Treatment for
Cryptosporidium
General Requirements
§ 141.700 General requirements.
(a) The requirements of this subpart
W are national primary drinking water
regulations. The regulations in this
subpart establish or extend treatment
technique requirements in lieu of
maximum contaminant levels for
Cryptosporidium. These requirements
are in addition to requirements for
filtration and disinfection in subparts H,
P, and T of this part.
(b) Applicability- The requirements of
this subpart apply to all subpart H
systems, which are public water systems
supplied by a surface water source and
public water systems supplied by a
ground water source under the direct
influence of surface water.
(1) Wholesale systems, as defined in
§ 141.2, must comply with the
requirements of this subpart based on
the population of the largest system in
the combined distribution system.
(2) The requirements of this subpart
for filtered systems apply to systems
required by National Primary Drinking
Water Regulations to provide filtration
treatment, whether or not the system is
currently operating a filtration system.
(3) The requirements of this subpart
for unfiltered systems apply only to
unfiltered systems that timely met and
continue to meet the filtration
avoidance criteria in subparts H, P, and
T of this part, as applicable.
(c) Requirements. Systems subject to
this subpart must comply with the
following requirements:
(1) Systems must conduct an initial
and a second round of source water
monitoring for each plant that treats a
surface water or GWUDI source. This
monitoring may include sampling for
Cryptosporidium, E. coli, and turbidity
as described in §§ 141.701 through
141.706, to determine what level, if any,
of additional Cryptosporidium treatment
they must provide.
(2) Systems that plan to make a
significant change to their disinfection
practice must develop disinfection
profiles and calculate disinfection
benchmarks, as described in §§ 141.708
through 141.709.
(3) Filtered systems must determine
their Cryptosporidium treatment bin
classification as described in § 141.710
and provide additional treatment for
Cryptosporidium, if required, as
described in § 141.711. All unfiltered
systems must provide treatment for
Cryptosporidium as described in
§ 141.712. Filtered and unfiltered
systems must implement
Cryptosporidium treatment according to
the schedule in § 141.713.
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Federal Register/Vol. 71, No. 3/Thursday, January 5. 2006/Rules and Regulations
(4) Systems with uncovered finished
water storage facilities must comply
with the requirements to cover the
facility or treat the discharge from the
facility as described in § 141.714.
[5) Systems required to provide
additional treatment for
Cryptospondium must implement
microbial toolbox options that are
designed and operated as described in
§§ 141.715 through 141.720.
(6) Systems must comply with the
applicable recordkeeping and reporting
requirements described in §§ 141.721
through 141.722.
(7) Systems must address significant
deficiencies identified in sanitary
surveys performed by EPA as described
in §141.723.
Source Water Monitoring Requirements
§141.701 Source water monitoring.
(a) Initial round of source water
monitoring. Systems must conduct the
following monitoring on the schedule in
paragraph (c) of this section unless they
meet the monitoring exemption criteria
in paragraph (d) of this section.
(1) Filtered systems serving at least
10.000 people must sample their source
water for Cryptospondium. E. coli, and
turbidity at least monthly for 24 months.
[2) Unfiltered systems serving at least
10,000 people must sample their source
water for Cryptospondium at least
monthly for 24 months.
(3)(i) Filtered systems serving fewer
than 10,000 people must sample their
source water for E. coli at least once
everv two weeks for 12 months.
(ii) A filtered system serving fewer
than 10,000 people may avoid E. coli
monitoring if the system notifies the
State that it will monitor for
Cryptospondium as described in
paragraph (a)(4) of this section. The
system must notify the State no later
than 3 months prior to the date the
system is otherwise required to start E.
coli monitoring under § 141.701(c).
(4) Filtered systems serving fewer
than 10,000 people must sample their
source water for Cryptosporidium at
least twice per month for 12 months or
at least monthly for 24 months if they
meet one of the following, based on
monitoring conducted under paragraph
(a)(3) of this section:
(i) For systems using lake/reservoir
sources, the annual mean E. coli
concentration is greater than 10 E. coli/
100 mL.
(ii) For systems using flowing stream
sources, the annual mean E. coli
concentration is greater than 50 E. coli/
100 mL.
(iii) The system does not conduct E.
coli monitoring as described in
paragraph (a)(3) of this section.
(iv) Systems using ground water
under the direct influence of surface
water (GWUDI) must comply with the
requirements of paragraph (a)(4) of this
section based on the E. coli level that
applies to the nearest surface water
body. If no surface water body is nearby,
the system must comply based on the
requirements that apply to systems
using lake/reservoir sources.
[5) For filtered systems serving fewer
than 10,000 people, the State may
approve monitoring for an indicator
other than E. coli under paragraph (a)(3)
of this section. The State also may
approve an alternative to the E. coli
concentration in paragraph (a)(4)(i), (ii)
or (iv) of this section to trigger
Cryptospondium monitoring. This
approval by the State must be provided
to the system in writing and must
include the basis for the State's
determination that the alternative
indicator and/or trigger level will
provide a more accurate identification
of whether a system will exceed the Bin
1 Cryptospondium level in § 141.710.
(6) Unfiltered systems serving fewer
than 10,000 people must sample their
source water for Cryptosporidium at
least twice per month for 12 months or
at least monthly for 24 months.
(7) Systems may sample more
frequently than required under this
section if the sampling frequency is
evenly spaced throughout the
monitoring period.
(b) Second round of source water
monitoring. Systems must conduct a
second round of source water
monitoring that meets the requirements
for monitoring parameters, frequency,
and duration described in paragraph (a)
of this section, unless they meet the
monitoring exemption criteria in
paragraph (d) of this section. Systems
must conduct this monitoring on the
schedule in paragraph (c) of this section.
(c) Monitoring schedule. Systems
must begin the monitoring required in
paragraphs (a) and (b) of this section no
later than the month beginning with the
date listed in this table:
SOURCE WATER MONITORING STARTING DATES TABLE
Systems that serve
Must begin the first round of source water
monitoring no later than the month
beginning
And must begin the second round of source
water monitoring no later than the month be-
ginning .
(1) At least 100,000 people
(2) From 50,000 to 99,999 people
(3) From 10,000 to 49,999 people
(4) Fewer than 10,000 and monitor for E. co//a
(5) Fewer than 10,000 and monitor for
Cryptosporidium^.
(i) October 1, 2006
(i) April 1, 2007 ..
(i) April 1, 2008 . ...
(i) October 1, 2008 .
(i) April 1, 2010
(n)-April 1, 2015
(ii) October 1, 2015
(n) October 1, 2016
(n) October 1, 2017.
(n) April 1, 2019
a Applies only to filtered systems.
b Applies to filtered systems that meet the conditions of paragraph (a)(4) of this section and unfiltered systems.
(d) Monitoring avoidance. (1) Filtered
systems are not required to conduct
source water monitoring under this
subpart if the system will provide a total
of at least 5.5-log of treatment for
Cryptospondium. equivalent to meeting
the treatment requirements of Bin 4 in
§141.711.
(2) Unfiltered systems are not
required to conduct source water
monitoring under this subpart if the
system will provide a total of at least 3-
log Cryptosporidium inactivation,
equivalent to meeting the treatment
requirements for unfiltered systems
with a mean Cryptosporidium
concentration of greater than 0.01
oocysts/Lin §141.712.
(3) If a system chooses to provide the
level of treatment in paragraph (d)(l) or
(2) of this section, as applicable, rather
than start source water monitoring, the
system must notify the State in writing
no later than the date the system is
otherwise required to submit a sampling
schedule for monitoring under
§ 141.702. Alternatively, a system may
choose to stop sampling at any point
after it has initiated monitoring if it
notifies the State in writing that it will
provide this level of treatment. Systems
must install and operate technologies to
provide this level of treatment by the
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771
applicable treatment compliance date in
§141.713.
(e) Plants operating only part of the
year. Systems with subpart H plants that
operate for only part of the year must
conduct source water monitoring in
accordance with this subpart, but with
the following modifications:
(1) Systems must sample their source
water only during the months that the
plant operates unless the State specifies
another monitoring period based on
plant operating practices.
(2) Systems with plants that operate
less than six months per year and that
monitor for Cryptosporidium must
collect at least six Cryptosporidium
samples per year during each of two
years of monitoring. Samples must be
evenly spaced throughout the period the
plant operates.
(f)(l) New sources. A system that
begins using a new source of surface
water or GWUDI after the system is
required to begin monitoring under
paragraph (c) of this section must
monitor the new source on a schedule
the State approves. Source water
monitoring must meet the requirements
of this subpart. The system must also
meet the bin classification and
Cryptosporidium treatment
requirements of §§ 141.710 and 141.711
or § 141.712, as applicable, for the new
source on a schedule the State approves.
(2) The requirements of § 141.701(f)
apply to subpart H systems that begin
operation after the monitoring start date
applicable to the system's size under
paragraph (c) of this section.
(3) The system must begin a second
round of source water monitoring no
later than 6 years following initial bin
classification under § 141.710 or
determination of the mean
Cryptosporidium level under § 141.712,
as applicable.
(g) Failure to collect any source water
sample required under this section in
accordance with the sampling schedule,
sampling location, analytical method,
approved laboratory, and reporting
requirements of §§ 141.702 through
141.706 is a monitoring violation.
(h) Grandfathering monitoring data.
Systems may use (grandfather)
monitoring data collected prior to the
applicable monitoring start date in
paragraph (c) of this section to meet the
initial source water monitoring
requirements in paragraph (a) of this
section. Grandfathered data may
substitute for an equivalent number of
months at the end of the monitoring
period. All data submitted under this
paragraph must meet the requirements
in §141.707.
§141.702 Sampling schedules.
(a) Systems required to conduct
source water monitoring under
§ 141.701 must submit a sampling
schedule that specifies the calendar
dates when the system will collect each
required sample.
(1) Systems must submit sampling
schedules no later than 3 months prior
to the applicable date listed in
§ 141.701(c) for each round of required
monitoring.
(2)(i) Systems serving at least 10,000
people must submit their sampling
schedule for the initial round of source
water monitoring under § 141.701(a) to
EPA electronically at https://
intranet.epa.gov/lt2/.
(ii) If a system is unable to submit the
sampling schedule electronically, the
system may use an alternative approach
for submitting the sampling schedule
that EPA approves.
(3) Systems serving fewer than 10,000
people must submit their sampling
schedules for the initial round of source
water monitoring § 141.701(a) to the
State.
(4) Systems must submit sampling
schedules for the second round of
source water monitoring § 141.701(b) to
the State.
(5) If EPA or the State does not
respond to a system regarding its
sampling schedule, the system must
sample at the reported schedule.
(b) Systems must collect samples
within two days before or two days after
the dates indicated in their sampling
schedule (i.e., within a five-day period
around the schedule date) unless one of
the conditions of paragraph (b)(l) or (2)
of this section applies.
(1) If an extreme condition or
situation exists that may pose danger to
the sample collector, or that cannot be
avoided and causes the system to be
unable to sample in the scheduled five-
day period, the system must sample as
close to the scheduled date as is feasible
unless the State approves an alternative
sampling date. The system must submit
an explanation for the delayed sampling
date to the State concurrent with the
shipment of the sample to the
laboratory.
(2)(i) If a system is unable to report a
valid analytical result for a scheduled
sampling date due to equipment failure,
loss of or damage to the sample, failure
to comply with the analytical method
requirements, including the quality
control requirements in § 141.704, or the
failure of an approved laboratory to
analyze the sample, then the system
must collect a replacement sample.
(ii) The system must collect the
replacement sample not later than 21
days after receiving information that an
analytical result cannot be reported for
the scheduled date unless the system
demonstrates that collecting a
replacement sample within this time
frame is not feasible or the State
approves an alternative resampling date.
The system must submit an explanation
for the delayed sampling date to the
State concurrent with the shipment of
the sample to the laboratory.
(c) Systems that fail to meet the
criteria of paragraph (b) of this section
for any source water sample required
under § 141.701 must revise their
sampling schedules to add dates for
collecting all missed samples. Systems
must submit the revised schedule to the
State for approval prior to when the
system begins collecting the missed
samples.
§ 141.703 Sampling locations.
(a) Systems required to conduct
source water monitoring under
§ 141.701 must collect samples for each
plant that treats a surface water or
GWUDI source. Where multiple plants
draw water from the same influent, such
as the same pipe or intake, the State
may approve one set of monitoring
results to be used to satisfy the
requirements of § 141.701 for all plants.
(b)(l) Systems must collect source
water samples prior to chemical
treatment, such as coagulants, oxidants
and disinfectants, unless the system
meets the condition of paragraph (b)(2)
of this section.
(2) The State may approve a system to
collect a source water sample after
chemical treatment. To grant this
approval, the State must determine that
collecting a sample prior to chemical
treatment is not feasible for the system
and that the chemical treatment is
unlikely to have a significant adverse
effect on the analysis of the sample.
(c) Systems that recycle filter
backwash water must collect source
water samples prior to the point of filter
backwash water addition.
(d) Bank filtration. (1) Systems that
receive Cryptosporidium treatment
credit for bank filtration under
§ 141.173(b) or § 141.552(a), as
applicable, must collect source water
samples in the surface water prior to
bank filtration.
(2) Systems that use bank filtration as
pretreatment to a filtration plant must
collect source water samples from the
well (i.e., after bank filtration). Use of
bank filtration during monitoring must
be consistent with routine operational
practice. Systems collecting samples
after a bank filtration process may not
receive treatment credit for the bank
filtration under § 141.717(c).
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
(e) Multiple sources. Systems with
plants that use multiple water sources,
including multiple surface water
sources and blended surface water and
ground water sources, must collect
samples as specified in paragraph (e)(l)
or (2) of this section. The use of
multiple sources during monitoring
must be consistent with routine
operational practice.
(1) If a sampling tap is available
where the sources are combined prior to
treatment, systems must collect samples
from the tap.
(2) If a sampling tap where the
sources are combined prior to treatment
is not available, systems must collect
samples at each source near the intake
on the same day and must follow either
paragraph (e)(2)(i) or (ii) of this section
for sample analysis.
(i) Systems may composite samples
from each source into one sample prior
to analysis. The volume of sample from
each source must be weighted according
to the proportion of the source in the
total plant flow at the time the sample
is collected.
(ii) Systems may analyze samples
from each source separately and
calculate a weighted average of the
analysis results for each sampling date.
The weighted average must be
calculated by multiplying the analysis
result for each source by the fraction the
source contributed to total plant flow at
the time the sample was collected and
then summing these values.
(f) Additional Requirements. Systems
must submit a description of their
sampling location(s) to the State at the
same time as the sampling schedule
required under § 141.702. This
description must address the position of
the sampling location in relation to the
system's water source(s) and treatment
processes, including pretreatment,
points of chemical treatment, and filter
backwash recycle. If the State does not
respond to a system regarding sampling
location(s), the system must sample at
the reported location(s).
§141.704 Analytical methods.
(a) Cryptosporidium. Systems must
analyze for Crvptosporidnim using
Method 1623: Crvptosporidium and
Giardia in Water by Filtration/IMS/FA,
2005, United States Environmental
Protection Agency, EPA-815-R-05-002
or Method 1622: Cryptosporidium in
Water by Filtration/IMS/FA, 2005,
United States Environmental Protection
Agency, EPA-815-R-05-001, which are
incorporated by reference. The Director
of the Federal Register approves this
incorporation by reference in
accordance with 5 U.S.C. 552(a) and 1
CFR part 51. You may obtain a copy of
these methods online from http://
www.epa.gov/safewater/disinfection/lt2
or from the United States Environmental
Protection Agency, Office of Ground
Water and Drinking Water, 1201
Constitution Ave.. NW, Washington, DC
20460 (Telephone: 800-426-4791). You
may inspect a copy at the Water Docket
in the EPA Docket Center, 1301
Constitution Ave., NW, Washington,
DC, (Telephone: 202-566-2426) or at
the National Archives and Records
Administration (NARA). For
information on the availability of this
material at NARA, call 202-741-6030,
or go to: \\ttp://www.archives.gov/
federal^register/
code_of_federal_regulations/
ibrjocations.html.
(1) Systems must analyze at least a 10
L sample or a packed pellet volume of
at least 2 mL as generated by the
methods listed in paragraph (a) of this
section. Systems unable to process a 10
L sample must analyze as much sample
volume as can be filtered by two filters
approved by EPA for the methods listed
in paragraph (a) of this section, up to a
packed pellet volume of at least 2 mL.
(2)(i) Matrix spike (MS) samples, as
required by the methods in paragraph
(a) of this section, must be spiked and
filtered by a laboratory approved for
Cryptosporidium analysis under
§141.705.
(ii) If the volume of the MS sample is
greater than 10 L, the system may filter
all but 10 L of the MS sample in the
field, and ship the filtered sample and
the remaining 10 L of source water to
the laboratory. In this case, the
laboratory must spike the remaining 10
L of water and filter it through the filter
used to collect the balance of the sample
in the field.
(3) Flow cytometer-counted spiking
suspensions must be used for MS
samples and ongoing precision and
recovery (OPR) samples.
(b) E. coli. Systems must use methods
for enumeration of E. coli in source
water approved in §136.3(a) of this title.
(1) The time from sample collection to
initiation of analysis may not exceed 30
hours unless the system meets the
condition of paragraph (b)(2) of this
section.
(2) The State may approve on a case-
by-case basis the holding of an E. coli
sample for up to 48 hours between
sample collection and initiation of
analysis if the State determines that
analyzing an E. coli sample within 30
hours is not feasible. E. coli samples
held between 30 to 48 hours must be
analyzed by the Colilert reagent version
of Standard Method 9223B as listed in
§136.3(a) of this title.
(3) Systems must maintain samples
between 0°C and 10°C during storage
and transit to the laboratory.
(c) Turbidity Systems must use
methods for turbidity measurement
approved in § 141.74(a)(l).
§141.705 Approved laboratories.
(a) Cryptosporidium. Systems must
have Cryptosporidium samples analyzed
by a laboratory that is approved under
EPA's Laboratory Quality Assurance
Evaluation Program for Analysis of
Cryptosporidium in Water or a
laboratory that has been certified for
Cryptosporidium analysis by an
equivalent State laboratory certification
program.
(b) E. coli. Any laboratory certified by
the EPA, the National Environmental
Laboratory Accreditation Conference or
the State for total coliform or fecal
coliform analysis under § 141.74 is
approved for E. coli analysis under this
subpart when the laboratory uses the
same technique for E. call that the
laboratory uses for § 141.74.
(c) Turbidity. Measurements of
turbidity must be made by a party
approved by the State.
§141.706 Reporting source water
monitoring results.
(a) Systems must report results from
the source water monitoring required
under § 141.701 no later than 10 days
after the end of the first month
following the month when the sample is
collected.
(b)(l) All systems serving at least
10,000 people must report the results
from the initial source water monitoring
required under § 141.701(a) to EPA
electronically at https://
intranet.epa.gov/lt2/.
(2) If a system is unable to report
monitoring results electronically, the
system may use an alternative approach
for reporting monitoring results that
EPA approves.
(c) Systems serving fewer than 10,000
people must report results from the
initial source water monitoring required
under § 141.701(a) to the State.
(d) All systems must report results
from the second round of source water
monitoring required under § 141.701(b)
to the State.
(e) Systems must report the applicable
information in paragraphs (e)(l) and (2)
of this section for the source water
monitoring required under § 141.701.
(1) Systems must report the following
data elements for each Crvptosporidium
analysis:
Data element.
1. PWS ID.
2. Facility ID
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773
Data element
3. Sample collection date.
4. Sample type (field or matrix spike).
5. Sample volume filtered (L), to nearest 'A
L.
6. Was 100% of filtered volume examined.
7. Number of oocysts counted.
(i) For matrix spike samples, systems
must also report the sample volume
spiked and estimated number of oocysts
spiked. These data are not required for
field samples.
(ii) For samples in which less than 10
L is filtered or less than 100% of the
sample volume is examined, systems
must also report the number of filters
used and the packed pellet volume.
(iii) For samples in which less than
100% of sample volume is examined,
systems must also report the volume of
resuspended concentrate and volume of
this resuspension processed through
immunomagnetic separation.
(2) Systems must report the following
data elements for each E. coli analysis:
Data element
1 PWS ID
2. Facility ID.
3. Sample collection date.
4. Analytical method number.
5 Method type.
6 Source tvpe (flowing stream, lake/reservoir.
GWUDI).
7. E co/i/100 mL.
8. Turbidity.'
1 Systems serving fewer than 10.000 people
that are not required to monitor for turbidity
under §141.701 are not required to report
turbidity with their £. coli results.
§ 141.707 Grandfathering previously
collected data.
(a)(l) Systems may comply with the
initial source water monitoring
requirements of § 141.701(a) by
grandfathering sample results collected
before the system is required to begin
monitoring (i.e., previously collected
data). To be grandfathered, the sample
results and analysis must meet the
criteria in this section and the State
must approve.
(2) A filtered system may grandfather
Cryptosporidium samples to meet the
requirements of § 141.701(a) when the
system does not have corresponding E.
coli and turbidity samples. A system
that grandfathers Cryptosporidium
samples without E. coli and turbidity
samples is not required to collect E. coli
and turbidity samples when the system
completes the requirements for
Cryptosporidium monitoring under
§141.701(a).
(b) E. coli sample analysis. The
analysis oiE. coli samples must meet
the analytical method and approved
laboratory requirements of §§ 141.704
through 141.705.
(c) Cryptosporidium sample analysis.
The analysis of Crvptosporidium
samples must meet the criteria in this
paragraph.
(1) Laboratories analyzed
Cryptosporidium samples using one of
the analytical methods in paragraphs
(c)(l)(i) through (vi) of this section,
which are incorporated by reference.
The Director of the Federal Register
approves this incorporation by reference
in accordance with 5 U.S.C. 552(a) and
1 CFR part 51. You may obtain a copy
of these methods on-line from the
United States Environmental Protection
Agency, Office of Ground Water and
Drinking Water, 1201 Constitution Ave,
NW, Washington, DC 20460 (Telephone:
800-426-4791). You may inspect a copy
at the Water Docket in the EPA Docket "
Centerr 1301 Constitution Ave., NW,
Washington, DC, (Telephone: 202-566-
2426) or at the National Archives and
Records Administration (NARA). For
information on the availability of this
material at NARA, call 202-741-6030,
or go to: http://www.archives.gov/
federal_ register/code_of_federal_
regulations/ibrJocations.html.
(i) Method 1623: Cryptosporidium
and Giardia in Water by Filtration/IMS/
FA, 2005, United States Environmental
Protection Agency, EPA-815-R-05-002.
(ii) Method 1622: Crvptosporidium. in
Water by Filtration/IMS/FA, 2005,
United States Environmental Protection
Agency, EPA-815-R-05-001.
(iii) 'Method 1623: Cryptosporidium
and Giardia in Water by Filtration/IMS/
FA. 2001, United States Environmental
Protection Agency, EPA-821-R-01-025.
(iv) Method 1622: Cryptosporidium in
Water by Filtration/IMS/FA, 2001,
United States Environmental Protection
Agency, EPA-821—R-01-026.
(v) Method 1623: Cryptosporidium
and Giardia in Water by Filtration/IMS/
FA, 1999, United States Environmental
Protection Agency, EPA-821-R-99-006.
(vi) Method 1622: Cryptosporidium in
Water by Filtration/IMS/FA, 1999,
United States Environmental Protection
Agency, EPA-821-R-99-001.
(2) For each Cryptosporidium sample,
the laboratory analyzed at least 10 L of
sample or at least 2 mL of packed pellet
or as much volume as could be filtered
by 2 filters that EPA approved for the
methods listed in paragraph (c)(l) of
this section.
(d) Sampling location. The sampling
location must meet the conditions in
§141.703.
(e) Sampling frequency.
Cryptosporidium samples were
collected no less frequently than each
calendar month on a regular schedule,
•beginning no earlier than January 1999.
Sample collection intervals may vary for
the conditions specified in
§ 141.702(b)(l) and (2) if the system
provides documentation of the
condition when reporting monitoring
results.
(1) The State may approve
grandfathering of previously collected
data where there are time gaps in the
sampling frequency if the system
conducts additional monitoring the
State specifies to ensure that the data
used to comply with the initial source
water monitoring requirements of
§141.701(a) are seasonally
representative and unbiased.
(2) Systems may grandfather
previously collected data where the
sampling frequency within each month
varied. If the Cryptosporidium sampling
frequency varied, systems must follow
the monthly averaging procedure in
§ 141.710(b)(5) or § 141.712(a)(3), as
applicable, when calculating the bin
classification for filtered systems or the
mean Cryptosporidium concentration
for unfiltered systems.
(f) Reporting monitoring results for
grandfathering. Systems that request to
grandfather previously collected
monitoring results must report the
following information by the applicable
dates listed in this paragraph. Systems
serving at least 10,000 people must
report this information to EPA unless
the State approves reporting to the State
rather than EPA. Systems serving fewer
than 10,000 people must report this
information to the State.
(I) Systems must report that they
intend to submit previously collected
monitoring results for grandfathering.
This report must specify the number of
previously collected results the system
will submit, the dates of the first and
last sample, and whether a system will
conduct additional source water
monitoring to meet the requirements of
§ 141.701(a). Systems must report this
information no later than the date the
sampling schedule under § 141.702 is
required.
(2) Systems must report previously
collected monitoring results for
grandfathering, along with the
associated documentation listed in
paragraphs (f)(2)(i) through (iv) of this
section, no later than two months after
the applicable date listed in
§141.701(c).
(i) For each sample result, systems
must report the applicable data
elements in § 141.706.
(ii) Systems must certify that the
reported monitoring results include all
results the system generated during the
time period beginning with the first
reported result and ending with the
final reported result. This applies to
samples that were collected from the
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sampling location specified for source
water monitoring under this subpart,
not spiked, and analyzed using the
laboratory's routine process for the
analytical methods listed in this section.
(iii) Systems must certify that the
samples were representative of a plant's
source water(s) and the source water(s)
have not changed. Systems must report
a description of the sampling
location(s), which must address the
position of the sampling location in
relation to the system's water source(s)
and treatment processes, including
points of chemical addition and filter
backwash recycle.
(iv) For Cryptosporidium samples, the
laboratory or laboratories that analyzed
the samples must provide a letter
certifying that the quality control
criteria specified in the methods listed
in paragraph (c)(l) of this section were
met for each sample batch associated
with the reported results. Alternatively,
the laboratory may provide bench sheets
and sample examination report forms
for each field, matrix spike, IPR, OPR,
and method blank sample associated
with the reported results.
(g) If the State determines that a
previously collected data set submitted
for grandfathering was generated during
source water conditions that were not
normal for the system, such as a
drought, the State may disapprove the
data. Alternatively, the State may
approve the previously collected data if
the system reports additional source
water monitoring data, as determined by
the State, to ensure that the data set
used under § 141.710 or § 141.712
represents average source water
conditions for the system.
(h) If a system submits previously
collected data that fully meet the
number of samples required for initial
source water monitoring under
§ 141.701(a) and some of the data are
rejected due to not meeting the
requirements of this section, systems
must conduct additional monitoring to
replace rejected data on a schedule the
State approves. Systems are not required
to begin this additional monitoring until
two months after notification that data
have been rejected and additional
monitoring is necessary,
Disinfection Profiling and
Benchmarking Requirements
§141.708 Requirements when making a
significant change in disinfection practice.
(a) Following the completion of initial
source water monitoring under
§ 141.701(a), a system that plans to
make a significant change to its
disinfection practice, as defined in
paragraph (b) of this section, must
develop disinfection profiles and
calculate disinfection benchmarks for
Giardia lamblia and viruses as
described in § 141.709. Prior to
changing the disinfection practice, the
system must notify the State and must
include in this notice the information in
paragraphs (a)(l) through (3) of this
section.
(l) A completed disinfection profile
and disinfection benchmark for Giardia
lamblia and viruses as described in
§141.709.
(2) A description of the proposed
change in disinfection practice.
(3) An analysis of how the proposed
change will affect the current level of
disinfection.
(b) Significant changes to disinfection
practice are defined as follows:
(1) Changes to the point of
disinfection;
(2) Changes to the disinfectant(s) used
in the treatment plant;
(3) Changes to the disinfection
process; or
[4) Any other modification identified
by the State as a significant change to
disinfection practice.
§ 141.709 Developing the disinfection
profile and benchmark.
(a) Systems required to develop
disinfection profiles under §141.708
must follow the requirements of this
section. Systems must monitor at least
weekly for a period of 12 consecutive
months to determine the total log
inactivation for Giardia lamblia and
viruses. If systems monitor more
frequently, the monitoring frequency
must be evenly spaced. Systems that
operate for fewer than 12 months per
year must monitor weekly during the
period of operation. Systems must
determine log inactivation for Giardia
lamblia through the entire plant, based
on CT999 values in Tables 1.1 through
1.6, 2.1 and 3.1 of § 141.74(b) as
applicable. Systems must determine log
inactivation for viruses through the
entire treatment plant based on a
protocol approved by the State.
(b) Systems with a single point of
disinfectant application prior to the
entrance to the distribution system must
conduct the monitoring in paragraphs
(b)(l) through (4) of this section.
Systems with more than one point of
disinfectant application must conduct
the monitoring in paragraphs (b)(l)
through (4) of this section for each
disinfection segment. Systems must
monitor the parameters necessary to
determine the total inactivation ratio,
using analytical methods in § 141.74(a).
(1) For systems using a disinfectant
other than UV, the temperature of the
disinfected water must be measured at
each residual disinfectant concentration
sampling point during peak hourly flow
or at an alternative location approved by
the State.
(2) For systems using chlorine, the pH
of the disinfected water must be
measured at each chlorine residual
disinfectant concentration sampling
point during peak hourly flow or at an
alternative location approved by the
State.
(3) The disinfectant contact time(s) (t)
must be determined during peak hourly
flow.
(4) The residual disinfectant
concentration(s) (C) of the water before
or at the first customer and prior to each
additional point of disinfectant
application must be measured during
peak hourly flow.
(c) In lieu of conducting new
monitoring under paragraph (b) of this
section, systems may elect to meet the
requirements of paragraphs (c)(l) or (2)
of this section.
(1) Systems that have at least one year
of existing data that are substantially
equivalent to data collected under the
provisions of paragraph (b) of this
section may use these data to develop
disinfection profiles as specified in this
section if the system has neither made
a significant change to its treatment
practice nor changed sources since the
data were collected. Systems may
develop disinfection profiles using up to
three years of existing data.
(2) Systems may use disinfection
profile(s) developed under § 141.172 or
§§ 141.530 through 141.536 in lieu of
developing a new profile if the system
has neither made a significant change to
its treatment practice nor changed
sources since the profile was developed.
Systems that have not developed a virus
profile under § 141.172 or §§ 141.530
through 141.536 must develop a virus
profile using the same monitoring data
on which the Giardia lamblia profile is
based.
(d) Systems must calculate the total
inactivation ratio for Giardia lamblia as
specified in paragraphs (d)(l) through
(3) of this section.
(1) Systems using only one point of
disinfectant application may determine
the total inactivation ratio for the
disinfection segment based on either of
the methods in paragraph (d)(l)(i) or (ii)
of this section.
(i) Determine one inactivation ratio
(CTcalc/CT«q 9) before or at the first
customer during peak hourly flow.
(ii) Determine successive CTcalc/
CT99 9 values, representing sequential
inactivation ratios, between the point of
disinfectant application and a point
before or at the first customer during
peak hourly flow. The system must
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775
calculate the total inactivation ratio by
determining (CTcalc/CT99 9) for each
sequence and then adding the (CTcalc/
CT99 9) values together to determine (I
(CTcalc/CTw,)).
(2) Systems using more than one point
of disinfectant application before the
first customer must determine the CT
value of each disinfection segment
immediately prior to the next point of
disinfectant application, or for the final
segment, before or at the first customer,
during peak hourly flow. The (CTcalc/
CT999) value of each segment and (Z
(CTcalc/CT999)) must be calculated
using the method in paragraph (d)(l)(ii)
of this section.
(3) The system must determine the
total logs of inactivation by multiplying
the value calculated in paragraph (d)(l)
or (d)(2) of this section by 3.0.
(4) Systems must calculate the log of
inactivation for viruses using a protocol
approved by the State.
(e) Systems must use the procedures
specified in paragraphs (e)(l) and (2) of
this section to calculate a disinfection
benchmark.
(1) For each year of profiling data
collected and calculated under
paragraphs (a) through (d) of this
section, systems must determine the
lowest mean monthly level of both
Giardia lamblia and virus inactivation.
Systems must determine the mean
Giardia lamblia and virus inactivation
for each calendar month for each year of
profiling data by dividing the sum of
daily or weekly Giardia lamblia and
virus log inactivation by the number of
values calculated for that month.
(2) The disinfection benchmark is the
lowest monthly mean value (for systems
with one year of profiling data) or the
mean of the lowest monthly mean
values (for systems with more than one
year of profiling data) of Giardia lamblia
and virus log inactivation in each year
of profiling data.
Treatment Technique Requirements
§141.710 Bin classification for filtered
systems.
(a) Following completion of the initial
round of source water monitoring
required under § 141.701(a), filtered
systems must calculate an initial
Cryptosporidium bin concentration for
each plant for which monitoring was
required. Calculation of the bin
concentration must use the
Cryptosporidium results reported under
§ 141.701(a) and must follow the
procedures in paragraphs (b)(l) through
(5) of this section.
(b)(l) For systems that collect a total
of at least 48 samples, the bin
concentration is equal to the arithmetic
mean of all sample concentrations.
(2) For systems that collect a total of
at least 24 samples, but not more than
47 samples, the bin concentration is
equal to the highest arithmetic mean of
all sample concentrations in any 12
consecutive months during which
Cryptosporidium samples were
collected.
(3) For systems that serve fewer than
10,000 people and monitor for
Cryptosporidium for only one year (i.e.,
collect 24 samples in 12 months), the
bin concentration is equal to the
arithmetic mean of all sample
concentrations.
(4) For systems with plants operating
only part of the year that monitor fewer
than 12 months per year under
§ 141.701(e), the bin concentration is
equal to the highest arithmetic mean of
all sample concentrations during any
year of Cryptosporidium monitoring.
(5) If the monthly Cryptosporidium
sampling frequency varies, systems
must first calculate a monthly average
for each month of monitoring. Systems
must then use these monthly average
concentrations, rather than individual
sample concentrations, in the applicable
calculation for bin classification in
paragraphs (b)(l) through (4) of this
section.
(c) Filtered systems must determine
their initial bin classification from the
following table and using the
Cryptosporidium bin concentration
calculated under paragraphs (a)-(b) of
this section:
BIN CLASSIFICATION TABLE FOR FILTERED SYSTEMS
For systems that are:
With a Cryptosporidium bin concentration of
The bin classification is
. required to monitor for Cryptosporidium under
§141.701.
. . serving fewer than 10,000 people and NOT required
to monitor for Cryptosporidium under § 141 701 (a)(4)
Cryptosporidium <0 075 oocyst/L
0.075 oocysts/L 3.0 oocysts/L
NA
Bin 1.
Bin 2.
Bin 3.
Bin 4
Bin 1
1 Based on calculations in paragraph (a) or (d) of this section, as applicable.
(d) Following completion of the
second round of source water
monitoring required under § 141.701(b),
filtered systems must recalculate their
Cryptosporidium bin concentration
using the Cryptosporidium results
reported under § 141.701(b) and
following the procedures in paragraphs
(b)(l) through (4) of this section.
Systems must then redetermine their
bin classification using this bin
concentration and the table in paragraph
(c) of this section.
(e)(l) Filtered systems must report
their initial bin classification under
paragraph (c) of this section to the State
for approval no later than 6 months after
the system is required to complete
initial source water monitoring based on
the schedule in § 141.701(c).
(2) Systems must report their bin
classification under paragraph (d) of this
section to the State for approval no later
than 6 months after the system is
required to complete the second round
of source water monitoring based on the
schedule in § 141.701(c).
(3) The bin classification report to the
State must include a summary of source
water monitoring data and the
calculation procedure used to determine
bin classification.
(f) Failure to comply with the
conditions of paragraph (e) of this
section is a violation of the treatment
technique requirement.
§ 141.711 Filtered system additional
Cryptosporidium treatment requirements.
(a) Filtered systems must provide the
level of additional treatment for
Cryptosporidium specified in this
paragraph based on their bin
classification as determined under
§ 141.710 and according to the schedule
in §141.713.
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If the system
bin classifica-
tion IS ...
Bin 1
Bin 2
Bin 3
Bin 4
And the system uses the following filtration treatment in full compliance with subparts H, P, and T of this part (as applicable),
then the additional Cryptospondium treatment requirements are . . .
Conventional filtration treat-
ment
(including softening)
No additional treatment
1-log treatment
2-log treatment
2.5-loa treatment
Direct filtration
No additional treatment
1 ,5-log treatment
2 5-log treatment
3-loa treatment
Slow sand or diatomaceous
earth filtration
No additional treatment
1 -log treatment
2-log treatment
2 5-loa treatment
Alternative filtration tech-
nologies
No additional treatment
D
(2)
(3)
1 As determined by the State such that the total Cryptospondium removal and mactivation is at least 4.0-log.
2 As determined by the State such that the total Cryptospondium removal and mactivation is at least 5.0-log.
3 As determined by the State such that the total Cryptospondium removal and mactivation is at least 5.5-log
(b)[l) Filtered systems must use one
or more of the treatment and
management options listed in § 141.715.
termed the microbial toolbox, to comply
with the additional Cryptosporidium
treatment required in paragraph (a) of
this section.
(2) Systems classified in Bin 3 and
Bin 4 must achieve at least 1-log of the
additional Cryptosporidium treatment
required under paragraph (a) of this
section using either one or a
combination of the following: bag filters,
bank filtration, cartridge filters, chlorine
dioxide, membranes, ozone, or UV, as
described in §§ 141.716 through
141.720.
(c) Failure by a system in any month
to achieve treatment credit by meeting
criteria in §§ 141.716 through 141.720
for microbial toolbox options that is at
least equal to the level of treatment
required in paragraph (a) of this section
is a violation of the treatment technique
requirement.
(d) If the State determines during a
sanitary survey or an equivalent source
water assessment that after a system
completed the monitoring conducted
under § 141.701(a) or § 141.70l(b),
significant changes occurred in the
system's watershed that could lead to
increased contamination of the source
water by Cryptosporidium, the system
must take actions specified by the State
to address the contamination. These
actions may include additional source
water monitoring and/or implementing
microbial toolbox options listed in
§141.715.
§141.712 Unfiltered system
Cryptosporidium treatment requirements.
[a) Determination of mean
Cryptosporidium level. (1) Following
completion of the initial source water
monitoring required under § 141.701[a),
unfiltered systems must calculate the
arithmetic mean of all Cryptosporidium
sample concentrations reported under
§ 141,701(a). Systems must report this
value to the State for approval no later
than 6 months after the month the
system is required to complete initial
source water monitoring based on the
schedule in §141.701(c).
(2) Following completion of the
second round of source water
monitoring required under § 141.701(b),
unfiltered systems must calculate the
arithmetic mean of all Cryptosporidium
sample concentrations reported under
§ 141.701(h). Systems must report this
value to the State for approval no later
than 6 months after the month the
system is required to complete the
second round of source water
monitoring based on the schedule in
§141.701(c).
(3) If the monthly Cryptosporidium
sampling frequency varies, systems
must first calculate a monthly average
for each month of monitoring. Systems
must then use these monthly average
concentrations, rather than individual
sample concentrations, in the
calculation of the mean
Cryptosporidium level in paragraphs
(a)(l) or (2) of this section.
(4) The report to the State of the mean
Cryptosporidium levels calculated
under paragraphs (a)(l) and (2) of this
section must include a summary of the
source water monitoring data used for
the calculation.
(5) Failure to comply with the
conditions of paragraph (a) of this
section is a violation of the treatment
technique requirement.
(b) Cryptosporidium inactivation
requirements. Unfiltered systems must
provide the level of inactivation for
Cryptosporidium specified in this
paragraph, based on their mean
Cryptosporidium levels as determined
under paragraph (a) of this section and
according to the schedule in § 141.713.
(1) Unfiltered systems with a mean
Cryptosporidium level of 0.01 oocysts/L
or less must provide at least 2-log
Cryptosporidium inactivation.
(2) Unfiltered systems with a mean
Cryptosporidium level of greater than
0.01 oocysts/L must provide at least 3-
log Crypfosporidium inactivation.
(c) Inactivation treatment technology
requirements. Unfiltered systems must
use chlorine dioxide, ozone, or UV as
described in § 141.720 to meet the
Cryptosporidium inactivation
requirements of this section.
(1) Systems that use chlorine dioxide
or ozone and fail to achieve the
Cryptosporidium inactivation required
in paragraph (b) of this section on more
than one day in the calendar month are
in violation of the treatment technique
requirement.
(2) Systems that use UV light and fail
to achieve the Cryptosporidium
inactivation required in paragraph (b) of
this section by meeting the criteria in
§ 141.720(d)(3)(ii) are in violation of the
treatment technique requirement.
(d) Use of two disinfectants.
Unfiltered systems must meet the
combined Cryptosporidium inactivation
requirements of this section and Giardia
lamhlia and virus inactivation
requirements of § 141.72(a) using a
minimum of two disinfectants, and each
of two disinfectants must separately
achieve the total inactivation required
for either Cryptosporidium. Giardia
lamblia. or viruses.
§ 141.713 Schedule for compliance with
Cryptosporidium treatment requirements.
(a) Following initial bin classification
under § 141.710(c), filtered systems
must provide the level of treatment for
Cryptosporidium required under
§141.711 according to the schedule in
paragraph (c) of this section.
(b) Following initial determination of
the mean Cryptosporidium level under
§141.712{a)(l), unfiltered systems must
provide the level of treatment for
Cryptosporidium required under
§ 141.712 according to the schedule in
paragraph (c) of this section.
(c) Cryptosporidium treatment
compliance dates.
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
777
CRYPTOSPORIDIUM TREATMENT
COMPLIANCE DATES TABLE
Systems that serve
(1) At least 100,000
people
(2) From 50,000 to
99,999 people.
(3) From 10,000 to
49,999 people.
(4) Fewer than
10,000 people.
Must comply with
Cryptosporidium treat-
ment requirements no
later than . a
(i) April 1,2012.
(i) October 1, 2012.
(i) October 1, 2013
(i) October 1, 2014.
a States may allow up to an additional two
years for complying with the treatment require-
ment for systems making capital
improvements.
(d) If the bin classification for a
filtered system changes following the
second round of source water
monitoring, as determined under
§ 141.710(d), the system must provide
the level of treatment for
Cryptosporidium required under
§ 141.711 on a schedule the State
approves.
(e) If the mean Cryptosporidium level
for an unfiltered system changes
following the second round of
monitoring, as determined under
§ 141.712(a)(2), and if the system must
provide a different level of
Cryptosporidium treatment under
§ 141.712 due to this change, the system
must meet this treatment requirement
on a schedule the State approves.
§ 141.714 Requirements for uncovered
finished water storage facilities.
(a) Systems using uncovered finished
water storage facilities must comply
with the conditions of this section.
(b) Systems must notify the State of
the use of each uncovered finished
water storage facility no later than April
1,2008.
(c) Systems must meet the conditions
of paragraph (c)(l) or (2) of this section
for each uncovered finished water
storage facility or be in compliance with
a State-approved schedule to meet these
conditions no later than April 1, 2009.
(1) Systems must cover any uncovered
finished water storage facility.
(2) Systems must treat the discharge
from the uncovered finished water
storage facility to the distribution
system to achieve inactivation and/or
removal of at least 4-log virus, 3-log
Giardia lamblia, and 2-log
Cryptosporidium using a protocol
approved by the State.
(d) Failure to comply with the
requirements of this section is a
violation of the treatment technique
requirement.
Requirements for Microbial Toolbox
Components
§ 141.715 Microbial toolbox options for
meeting Cryptosporidium treatment
requirements.
(a)(l) Systems receive the treatment
credits listed in the table in paragraph
(b) of this section by meeting the
conditions for microbial toolbox options
described in §§ 141.716 through
141.720. Systems apply these treatment
credits to meet the treatment
requirements in § 141.711 or § 141.712,
as applicable.
(2) Unfiltered systems are eligible for
treatment credits for the microbial
toolbox options described in § 141.720
only.
(b) The following table summarizes
options in the microbial toolbox:
MICROBIAL TOOLBOX SUMMARY TABLE: OPTIONS, TREATMENT CREDITS AND CRITERIA
Toolbox Option
Cryptosporidium treatment credit with design and implementation criteria
Source Protection and Management Toolbox Options
(1) Watershed control program
(2) Alternative source/intake management
0.5-log credit for State-approved program comprising required elements, annual program sta-
tus report to State, and regular watershed survey. Unfiltered systems are not eligible for
credit. Specific criteria are in §141.716(a)
No prescribed credit Systems may conduct simultaneous monitoring for treatment bin classi-
fication at alternative intake locations or under alternative intake management strategies.
Specific criteria are in §141.716(b).
Pre Filtration Toolbox Options
(3) Presedimentation basin with coagulation
(4) Two-stage lime softening
(5) Bank filtration
0 5-log credit during any month that presedimentation basins achieve a monthly mean reduc-
tion of 0.5-log or greater in turbidity or alternative State-approved performance criteria. To
be eligible, basins must be operated continuously with coagulant addition and all plant flow
must pass through basins. Specific criteria are in §141 717(a).
0.5-log credit for two-stage softening where chemical addition and hardness precipitation occur
in both stages All plant flow must pass through both stages Single-stage softening is cred-
ited as equivalent to conventional treatment Specific criteria are in § 141.717(b).
0.5-log credit for 25-foot setback; 1.0-log credit for 50-foot setback; aquifer must be unconsoh-
dated sand containing at least 10 percent fines; average turbidity in wells must be less than
1 NTU. Systems using wells followed by filtration when conducting source water monitoring
must sample the well to determine bin classification and are not eligible for additional credit.
Specific criteria are in §141.717(c).
Treatment Performance Toolbox Options
(6) Combined filter performance
(7) Individual filter performance .
(8) Demonstration of performance
0.5-log credit for combined filter effluent turbidity less than or equal to 0.15 NTU in at least 95
percent of measurements each month. Specific criteria are in §141.7!8(a).
0.5-log credit (in addition to 0.5-log combined filter performance credit) if individual filter efflu-
ent turbidity is less than or equal to 0.15 NTU in at least 95 percent of samples each month
in each filter and is never greater than 0.3 NTU in two consecutive measurements in any fil-
ter. Specific criteria are in § 141.718(b)
Credit awarded to unit process or treatment tram based on a demonstration to the State with a
State- approved protocol. Specific criteria are in § 141.718(c).
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
MICROBIAL TOOLBOX SUMMARY TABLE: OPTIONS, TREATMENT CREDITS AND CRITERIA—Continued
Toolbox Option
Cryptosporidium treatment credit with design and implementation criteria
Additional Filtration Toolbox Options
(9) Bag or cartridge filters (individual filters)
(10) Bag or cartridge filters (in series)
(11) Membrane filtration
(12) Second stage filtration
(13) Slow sand filters
Up to 2-log credit based on the removal efficiency demonstrated during challenge testing with
a 1.0-log factor of safety. Specific criteria are in §141.719(a)
Up to 2.5-log credit based on the removal efficiency demonstrated during challenge testing
with a 0.5-log factor of safety Specific criteria are in § 141.719(a).
Log credit equivalent to removal efficiency demonstrated in challenge test for device if sup-
ported by direct integrity testing Specific criteria are in § 141.719(b).
0.5-log credit for second separate granular media filtration stage if treatment train includes co-
agulation prior to first filter. Specific criteria are in § 141.719(c)
2.5-log credit as a secondary filtration step, 3.0-log credit as a primary filtration process. No
prior chlorination for either option. Specific criteria are in § 141.719(d).
Inactivation Toolbox Options
(14) Chlorine dioxide
(15) Ozone
(16) UV
Log credit based on measured CT in relation to CT table Specific criteria in § 141.720(b)
Log credit based on measured CT in relation to CT table. Specific criteria in § 141.720(b)
Log credit based on validated UV dose in relation to UV dose table, reactor validation testing
required to establish UV dose and associated operating conditions. Specific criteria in
§141.720(d).
§ 141.716 Source toolbox components.
(a) Watershed control program.
Systems receive 0.5-log
Cryptosporidium treatment credit for
implementing a watershed control
program that meets the requirements of
this section.
(l) Systems that intend to apply for
the watershed control program credit
must notify the State of this intent no
later than two years prior to the
treatment compliance date applicable to
the system in §141.713.
(2) Systems must submit to the State
a proposed watershed control plan no
later than one year before the applicable
treatment compliance date in § 141.713.
The State must approve the watershed
control plan for the system to receive
watershed control program treatment
credit. The watershed control plan must
include the elements in paragraphs
(a)(2)(i) through (iv) of this section.
(i) Identification of an "area of
influence" outside of which the
likelihood of Cryptosporidium or fecal
contamination affecting the treatment
plant intake is not significant. This is
the area to be evaluated in future
watershed surveys under paragraph
(a)(5)(ii) of this section.
(ii) Identification of both potential
and actual sources of Cryptosporidium
contamination and an assessment of the
relative impact of these sources on the
system's source water quality.
{iii) An analysis of the effectiveness
and feasibility of control measures that
could reduce Cryptosporidium loading
from sources of contamination to the
system's source water.
(iv) A statement of goals and specific
actions the system will undertake to
reduce source water Cryptosporidium
levels. The plan must explain how the
actions are expected to contribute to
specific goals, identify watershed
partners and their roles, identify
resource requirements and
commitments, and include a schedule
for plan implementation with deadlines
for completing specific actions
identified in the plan.
(3) Systems with existing watershed
control programs (i.e., programs in place
on January 5, 2006) are eligible to seek
this credit. Their watershed control
plans must meet the criteria in
paragraph (a)(2) of this section and must
specify ongoing and future actions that
will reduce source water
Cryptosporidium levels.
(4) If the State does not respond to a
system regarding approval of a
watershed control plan submitted under
this section and the system meets the
other requirements of this section, the
watershed control program will be
considered approved and 0.5 log
Cryptosporidium treatment credit will
be awarded unless and until the State
subsequently withdraws such approval.
(5) Systems must complete the actions
in paragraphs (a)(5)(i) through (iii) of
this section to maintain the 0.5-log
credit.
(i) Submit an annual watershed
control program status report to the
State. The annual watershed control
program status report must describe the
system's implementation of the
approved plan and assess the adequacy
of the plan to meet its goals. It must
explain how the system is addressing
any shortcomings in plan
implementation, including those
previously identified by the State or as
the result of the watershed survey
conducted under paragraph (a)(5)(ii) of
this section. It must also describe any
significant changes that have occurred
in the watershed since the last
watershed sanitary survey. If a system
determines during implementation that
making a significant change to its
approved watershed control program is
necessary, the system must notify the
State prior to making any such changes.
If any change is likely to reduce the
level of source water protection, the
system must also list in its notification
the actions the system will take to
mitigate this effect.
(ii) Undergo a watershed sanitary
survey every three years for community
water systems and every five years for
noncommunity water systems and
submit the survey report to the State.
The survey must be conducted
according to State guidelines and by
persons the State approves.
(A) The watershed sanitary survey
must meet the following criteria:
encompass the region identified in the
State-approved watershed control plan
as the area of influence; assess the
implementation of actions to reduce
source water Cryptosporidium levels;
and identify any significant new sources
of Cryptosporidium.
(B) If the State determines that
significant changes may have occurred
in the watershed since the previous
watershed sanitary survey, systems
must undergo another watershed
sanitary survey by a date the State
requires, which may be earlier than the
regular date in paragraph (a)(5)(ii) of
this section.
(iii) The system must make the
watershed control plan, annual status
reports, and watershed sanitary survey
reports available to the public upon
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779
request. These documents must be in a
plain language style and include criteria
by which to evaluate the success of the
program in achieving plan goals. The
State may approve systems to withhold
from the public portions of the annual
status report, watershed control plan,
and watershed sanitary survey based on
water supply security considerations.
(6) If the State determines that a
system is not carrying out the approved
watershed control plan, the State may
withdraw the watershed control
program treatment credit.
(b) Alternative source. (1) A system
may conduct source water monitoring
that reflects a different intake location
(either in the same source or for an
alternate source) or a different
procedure for the timing or level of
withdrawal from the source (alternative
source monitoring). If the State
approves, a system may determine its
bin classification under § 141.710 based
on the alternative source monitoring
results.
(2) If systems conduct alternative
source monitoring under paragraph
(b)(l) of this section, systems must also
monitor their current plant intake
concurrently as described in § 141.701.
(3) Alternative source monitoring
under paragraph (b)(l) of this section
must meet the requirements for source
monitoring to determine bin
classification, as described in §§ 141.701
through 141.706. Systems must report
the alternative source monitoring results
to the State, along with supporting
information documenting the operating
conditions under which the samples
were collected.
(4) If a system determines its bin
classification under §141.710 using
alternative source monitoring results
that reflect a different intake location or
a different procedure for managing the
timing or level of withdrawal from the
source, the system must relocate the
intake or permanently adopt the
withdrawal procedure, as applicable, no
later than the applicable treatment
compliance date in § 141.713.
§ 141.717 Pre-f iltration treatment toolbox
components.
(a) Presedimentation. Systems receive
0.5-log Cryptosporidium treatment
credit for a presedimentation basin
during any month the process meets the
criteria in this paragraph.
(1) The presedimentation basin must
be in continuous operation and must
treat the entire plant flow taken from a
surface water or GWUDI source.
(2) The system must continuously add
a coagulant to the presedimentation
basin.
(3) The presedimentation basin must
achieve the performance criteria in
paragraph (3)(i) or (ii) of this section.
(i) Demonstrates at least 0.5-log mean
reduction of influent turbidity. This
reduction must be determined using
daily turbidity measurements in the
presedimentation process influent and
effluent and must be calculated as
follows: logiofmonthly mean of daily
influent turbidity) -logio(monthly mean
of daily effluent turbidity).
(ii) Complies with State-approved
performance criteria that demonstrate at
least 0.5-log mean removal of micron-
sized particulate material through the
presedimentation process.
(b) Two-stage lime softening. Systems
receive an additional 0.5-log
Cryptosporidium treatment credit for a
two-stage lime softening plant if
chemical addition and hardness
precipitation occur in two separate and
sequential softening stages prior to
filtration. Both softening stages must
treat the entire plant flow taken from a
surface water or GWUDI source.
(c) Bank filtration. Systems receive
Cryptosporidium treatment credit for
bank filtration that serves as
pretreatment to a filtration plant by
meeting the criteria in this paragraph.
Systems using bank filtration when they
begin source water monitoring under
§ 141.701(a) must collect samples as
described in § 141.703(d) and are not
eligible for this credit.
(1) Wells with a ground water flow
path of at least 25 feet receive 0.5-log
treatment credit; wells with a ground
water flow path of at least 50 feet
receive 1.0-log treatment credit. The
ground water flow path must be
determined as specified in paragraph
(c)(4) of this section.
(2) Only wells in granular aquifers are
eligible for treatment credit. Granular
aquifers are those comprised of sand,
clay, silt, rock fragments, pebbles or
larger particles, and minor cement. A
system must characterize the aquifer at
the well site to determine aquifer
properties. Systems must extract a core
from the aquifer and demonstrate that in
at least 90 percent of the core length,
grains less than 1.0 mm in diameter
constitute at least 10 percent of the core
material.
(3) Only horizontal and vertical wells
are eligible for treatment credit.
(4) For vertical wells, the ground
water flow path is the measured
distance from the edge of the surface
water body under high flow conditions
(determined by the 100 year floodplain
elevation boundary or by the floodway,
as defined in Federal Emergency
Management Agency flood hazard
maps) to the well screen. For horizontal
wells, the ground water flow path is the
measured distance from the bed of the
river under normal flow conditions to
the closest horizontal well lateral
screen.
(5) Systems must monitor each
wellhead for turbidity at least once
every four hours while the bank
filtration process is in operation. If
monthly average turbidity levels, based
on daily maximum values in the well,
exceed 1 NTU, the system must report
this result to the State and conduct an
assessment within 30 days to determine
the cause of the high turbidity levels in
the well. If the State determines that
microbial removal has been
compromised, the State may revoke
treatment credit until the system
implements corrective actions approved
by the State to remediate the problem.
' (6) Springs and infiltration galleries
are not eligible for treatment credit
under this section, but are eligible for
credit under § 141.718(c).
(7) Bank filtration demonstration of
performance. The State may approve
Cryptosporidium treatment credit for
bank filtration based on a demonstration
of performance study that meets the
criteria in this paragraph. This treatment
credit may be greater than 1.0-log and
may be awarded to bank filtration that
does not meet the criteria in paragraphs
(c)(l)-(5) of this section.
(i) The study must follow a State-
approved protocol and must involve the
collection of data on the removal of
Cryptosporidium or a surrogate for
Cryptosporidium and related
hydrogeologic and water quality
parameters during the full range of
operating conditions.
(ii) The study must include sampling
both from the production well(s) and
from monitoring wells that are screened
and located along the shortest flow path
between the surface water source and
the production well(s).
§ 141.718 Treatment performance toolbox
components.
(a) Combined filter performance.
Systems using conventional filtration
treatment or direct filtration treatment
receive an additional 0.5-log
Cryptosporidium treatment credit
during any month the system meets the
criteria in this paragraph. Combined
filter effluent (CFE) turbidity must be
less than or equal to 0.15 NTU in at least
95 percent of the measurements.
Turbidity must be measured as
described in § 141.74(a) and (c).
(b) Individual filter performance.
Systems using conventional filtration
treatment or direct filtration treatment
receive 0.5-log Cryptosporidium
treatment credit, which can be in
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
addition to the 0.5-log credit under
paragraph (a) of this section, during any
month the system meets the criteria in
this paragraph. Compliance with these
criteria must be based on individual
filter turbidity monitoring as described
in § 141.174 or § 141.560, as applicable.
(1) The filtered water turbidity for
each individual filter must be less than
or equal to 0.15 NTU in at least 95
percent of the measurements recorded
each month.
(2) No individual filter may have a
measured turbidity greater than 0.3 NTU
in two consecutive measurements taken
15 minutes apart.
(3) Any system that has received
treatment credit for individual filter
performance and fails to meet the
requirements of paragraph (b)(l) or (2)
of this section during any month does
not receive a treatment technique
violation under § 141.711(c) if the State
determines the following:
(i) The failure was due to unusual and
short-term circumstances that could not
reasonably be prevented through
optimizing treatment plant design,
operation, and maintenance.
(ii) The system has experienced no
more than two such failures in any
calendar year.
(c) Demonstration of performance.
The State may approve Cryptosporidium
treatment credit for drinking water
treatment processes based on a
demonstration of performance study
that meets the criteria in this paragraph.
This treatment credit may be greater
than or less than the prescribed
treatment credits in § 141.711 or
§§ 141.717 through 141.720 and may be
awarded to treatment processes that do
not meet the criteria for the prescribed
credits.
(1) Systems cannot receive the
prescribed treatment credit for any
toolbox box option in §§ 141.717
through 141.720 if that toolbox option is
included in a demonstration of
performance study for which treatment
credit is awarded under this paragraph.
(2) The demonstration of performance
study must follow a State-approved
protocol and must demonstrate the level
of Cnrptosporidium reduction the
treatment process will achieve under
the full range of expected operating
conditions for the system.
(3) Approval by the State must be in
writing and may include monitoring
and treatment performance criteria that
the system must demonstrate and report
on an ongoing basis to remain eligible
for the treatment credit. The State may
designate such criteria where necessary
to verify that the conditions under
which the demonstration of
performance credit was approved are
maintained during routine operation.
§ 141.719 Additional filtration toolbox
components.
(a) Bag and cartridge filters. Systems
receive Cryptosporidium treatment
credit of up to 2.0-log for individual bag
or cartridge filters and up to 2.5-log for
bag or cartridge filters operated in series
by meeting the criteria in paragraphs
(a)(l) through (10) of this section. To be
eligible for this credit, systems must
report the results of challenge testing
that meets the requirements of
paragraphs (a)(2) through (9) of this
section to the State. The filters must
treat the entire plant flow taken from a
subpart H source.
(1) The Cryptosporidium treatment
credit awarded to bag or cartridge filters
must be based on the removal efficiency
demonstrated during challenge testing
that is conducted according to the
criteria in paragraphs (a)(2) through
(a)(9) of this section. A factor of safety
equal to 1-log for individual bag or
cartridge filters and 0.5-log for bag or
cartridge filters in series must be
applied to challenge testing results to
determine removal credit. Systems may
use results from challenge testing
conducted prior to January 5, 2006 if the
prior testing was consistent with the
criteria specified in paragraphs (a)(2)
through (9) of this section.
(2) Challenge testing must be
performed on full-scale bag or cartridge
filters, and the associated filter housing
or pressure vessel, that are identical in
material and construction to the filters
and housings the system will use for
removal of Cryptosporidium. Bag or
cartridge filters must be challenge tested
in the same configuration that the
system will use, either as individual
filters or as a series configuration of
filters.
(3) Challenge testing must be
conducted using Cryptosporidium or a
surrogate that is removed no more
efficiently than Cryptosporidium. The
microorganism or surrogate used during
challenge testing is referred to as the
challenge participate. The concentration
of the challenge particulate must be
determined using a method capable of
discreetly quantifying the specific
microorganism or surrogate used in the
test; gross measurements such as
turbidity may not be used.
(4) The maximum feed water
concentration that can be used during a
challenge test must be based on the
detection limit of the challenge
particulate in the filtrate (i.e., filtrate
detection limit) and must be calculated
using the following equation:
Maximum Feed Concentration = 1 x 10 4
x (Filtrate Detection Limit)
(5) Challenge testing must be
conducted at the maximum design flow
rate for the filter as specified by the
manufacturer.
(6) Each filter evaluated must be
tested for a duration sufficient to reach
100 percent of the terminal pressure
drop, which establishes the maximum
pressure drop under which the filter
may be used to comply with the
requirements of this subpart.
(7) Removal efficiency of a filter must
be determined from the results of the
challenge test and expressed in terms of
log removal values using the following
equation:
LRV = LOGio(Cr) - LOG,o(Cr)
Where:
LRV = log removal value demonstrated
during challenge testing; G = the
feed concentration measured during
the challenge test; and Cp = the
filtrate concentration measured
during the challenge test. In
applying this equation, the same
units must be used for the feed and
filtrate concentrations. If the
challenge particulate is not detected
in the filtrate, then the term Cp must
be set equal to the detection limit.
(8) Each filter tested must be
challenged with the challenge
particulate during three periods over the
filtration cycle: within two hours of
start-up of a new filter; when the
pressure drop is between 45 and 55
percent of the terminal pressure drop;
and at the end of the cycle after the
pressure drop has reached 100 percent
of the terminal pressure drop. An LRV
must be calculated for each of these
challenge periods for each filter tested.
The LRV for the filter (LRVfIhc,) must be
assigned the value of the minimum LRV
observed during the three challenge
periods for that filter.
(9) If fewer than 20 filters are tested,
the overall removal efficiency for the
filter product line must be set equal to
the lowest LRV),!,,,, among the filters
tested. If 20 or more filters are tested,
the overall removal efficiency for the
filter product line must be set equal to
the 10th percentile of the set of LRVf,],c,-
values for the various filters tested. The
percentile is defined by (i/(n+l)) where
i is the rank of n individual data points
ordered lowest to highest. If necessary,
the 10th percentile may be calculated
using linear interpolation.
(10) If a previously tested filter is
modified in a manner that could change
the removal efficiency of the filter
product line, challenge testing to
demonstrate the removal efficiency of
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
781
the modified filter must be conducted
and submitted to the State.
(b) Membrane filtration. (I) Systems
receive Cryptosporidium treatment
credit for membrane filtration that meets
the criteria of this paragraph. Membrane
cartridge filters that meet the definition
of membrane filtration in § 141.2 are
eligible for this credit. The level of
treatment credit a system receives is
equal to the lower of the values
determined under paragraph (b)(l)(i)
and (ii) of this section.
(i) The removal efficiency
demonstrated during challenge testing
conducted under the conditions in
paragraph (b)(2) of this section.
(ii) The maximum removal efficiency
that can be verified through direct
integrity testing used with the
membrane filtration process under the
conditions in paragraph (b)(3) of this
section.
(2) Challenge Testing. The membrane
used by the system must undergo
challenge testing to evaluate removal
efficiency, and the system must report
the results of challenge testing to the
State. Challenge testing must be
conducted according to the criteria in
paragraphs (b)(2)(i) through (vii) of this
section. Systems may use data from
challenge testing conducted prior to
January 5, 2006 if the prior testing was
consistent with the criteria in
paragraphs (b)(2)(i) through (vii) of this
section.
(i) Challenge testing must be
conducted on either a full-scale
membrane module, identical in material
and construction to the membrane
modules used in the system's treatment
facility, or a smaller-scale membrane
module, identical in material and
similar in construction to the full-scale
module. A module is defined as the
smallest component of a membrane unit
in which a specific membrane surface
area is housed in a device with a filtrate
outlet structure.
(ii) Challenge testing must be
conducted using Cryptosporidium
oocysts or a surrogate that is removed
no more efficiently than
Cryptosporidium oocysts. The organism
or surrogate used during challenge
testing is referred to as the challenge
particulate. The concentration of the
challenge particulate, in both the feed
and filtrate water, must be determined
using a method capable of discretely
quantifying the specific challenge
particulate used in the test; gross
measurements such as turbidity may not
be used.
(iii) The maximum feed water
concentration that can be used during a
challenge test is based on the detection
limit of the challenge particulate in the
filtrate and must be determined
according to the following equation:
Maximum Feed Concentration = 3.16 x
106 x (Filtrate Detection Limit)
(iv) Challenge testing must be
conducted under representative
hydraulic conditions at the maximum
design flux and maximum design
process recovery specified by the
manufacturer for the membrane module.
Flux is defined as the throughput of a
pressure driven membrane process
expressed as flow per unit of membrane
area. Recovery is defined as the
volumetric percent of feed water that is
converted to filtrate over the course of
an operating cycle uninterrupted by
events such as chemical cleaning or a
solids removal process (i.e.,
backwashing).
(v) Removal efficiency of a membrane
module must be calculated from the
challenge test results and expressed as
a log removal value according to the
following equation:
LRV = LOGio(Cf) x LOG,o(Cp)
Where:
LRV = log removal value demonstrated
during the challenge test; Cf = the
feed concentration measured during
the challenge test; and CP = the
filtrate concentration measured
during the challenge test.
Equivalent units must be used for
the feed and filtrate concentrations.
If the challenge particulate is not
detected in the filtrate, the term Cr
is set equal to the detection limit for
the purpose of calculating the LRV.
An LRV must be calculated for each
membrane module evaluated during
the challenge test.
(vi) The removal efficiency of a
membrane filtration process
demonstrated during challenge testing
must be expressed as a log removal
value (LRVc-TcJ. If fewer than 20
modules are tested, then LRVt--Tesi is
equal to the lowest of the representative
LRVs among the modules tested. If 20 or
more modules are tested, then LRVc-xesi
is equal to the 10th percentile of the
representative LRVs among the modules
tested. The percentile is defined by
(i/(n+l)) where i is the rank of n
individual data points ordered lowest to
highest. If necessary, the 10th percentile
may be calculated using linear
interpolation.
(vii) The challenge test must establish
a quality control release value (QCRV)
for a non-destructive performance test
that demonstrates the Cryptosporidium
removal capability of the membrane
filtration module. This performance test
must be applied to each production
membrane module used by the system
that was not directly challenge tested in
order to verify Cryptosporidium removal
capability. Production modules that do
not meet the established QCRV are not
eligible for the treatment credit
demonstrated during the challenge test.
(viii) If a previously tested membrane
is modified in a manner that could
change the removal efficiency of the
membrane or the applicability of the
non-destructive performance test and
associated QCRV, additional challenge
testing to demonstrate the removal
efficiency of, and determine a new
QCRV for, the modified membrane must
be conducted and submitted to the
State.
(3) Direct integrity testing. Systems
must conduct direct integrity testing in
a manner that demonstrates a removal
efficiency equal to or greater than the
removal credit awarded to the
membrane filtration process and meets
the requirements described in
paragraphs (b)(3)(i) through (vi) of this
section. A direct integrity test is defined
as a physical test applied to a membrane
unit in order to identify and isolate
integrity breaches (i.e., one or more
leaks that could result in contamination
of the filtrate).
(i) The direct integrity test must be
independently applied to each
membrane unit in service. A membrane
unit is defined as a group of membrane
modules that share common valving
that allows the unit to be isolated from
the rest of the system for the purpose of
integrity testing or other maintenance.
(ii) The direct integrity method must
have a resolution of 3 micrometers or
less, where resolution is defined as the
size of the smallest integrity breach that
contributes to a response from the direct
integrity test.
(iii) The direct integrity test must
have a sensitivity sufficient to verify the
log treatment credit awarded to the
membrane filtration process by the
State, where sensitivity is defined as the
maximum log removal value that can be
reliably verified by a direct integrity
test. Sensitivity must be determined
using the approach in either paragraph
(b)(3)(iii)(A) or (B) of this section as
applicable to the type of direct integrity
test the system uses.
(A) For direct integrity tests that use
an applied pressure or vacuum, the
direct integrity test sensitivity must be
calculated according to the following
equation:
LRVDIT = LOG,,, (Qp /(VCF x Qhreach))
Where:
LRVoix = the sensitivity of the direct
integrity test; Qp = total design
filtrate flow from the membrane
unit; Qbreach = flow of water from an
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Federal Register/ Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
integrity breach associated with the
smallest integrity test response that
can be reliably measured, and VCF
= volumetric concentration factor.
The volumetric concentration factor
is the ratio of the suspended solids
concentration on the high pressure
side of the membrane relative to
that in the feed water.
(B) For direct integrity tests that use
a particulate or molecular marker, the
direct integrity test sensitivity must be
calculated according to the following
equation:
LRVDIT = LOG,o(Cf) - LOG10(CP)
Where:
LRVDiT = the sensitivity of the direct
integrity test; Cf = the typical feed
concentration of the marker used in
the test; and Cr = the filtrate
concentration of the marker from an
integral membrane unit.
(iv) Systems must establish a control
limit within the sensitivity limits of the
direct integrity test that is indicative of
an integral membrane unit capable of
meeting the removal credit awarded by
the State.
(v) If the result of a direct integrity
test exceeds the control limit
established under paragraph (b)(3)(iv) of
this section, the system must remove the
membrane unit from service. Systems
must conduct a direct integrity test to
verify any repairs, and may return the
membrane unit to service only if the
direct integrity test is within the
established control limit.
(vi) Systems must conduct direct
integrity testing on each membrane unit
at a frequency of not less than once each
day that the membrane unit is in
operation. The State may approve less
frequent testing, based on demonstrated
process reliability, the use of multiple
barriers effective for Cryptosporidium,
or reliable process safeguards.
(4) Indirect integrity monitoring.
Systems must conduct continuous
indirect integrity monitoring on each
membrane unit according to the criteria
in paragraphs (b)(4)(i) through (v) of this
section. Indirect integrity monitoring is
defined as monitoring some aspect of
filtrate water quality that is indicative of
the removal of particulate matter. A
system that implements continuous
direct integrity testing of membrane
units in accordance with the criteria in
paragraphs (b)(3)(i) through (v) of this
section is not subject to the
requirements for continuous indirect
integrity monitoring. Systems must
submit a monthly report to the State
summarizing all continuous indirect
integrity monitoring results triggering
direct integrity testing and the
corrective action that was taken in each
case.
(i) Unless the State approves an
alternative parameter, continuous
indirect integrity monitoring must
include continuous filtrate turbidity
monitoring.
(ii) Continuous monitoring must be
conducted at a frequency of no less than
once every 15 minutes.
(iii) Continuous monitoring must be
separately conducted on each
membrane unit.
(iv) If indirect integrity monitoring
includes turbidity and if the filtrate
turbidity readings are above 0.15 NTU
for a period greater than 15 minutes
(i.e., two consecutive 15-minute
readings above 0.15 NTU), direct
integrity testing must immediately be
performed on the associated membrane
unit as specified in paragraphs (b)(3)(i)
through (v) of this section.
(v) If indirect integrity monitoring
includes a State-approved alternative
parameter and if the alternative
parameter exceeds a State-approved
control limit for a period greater than 15
minutes, direct integrity testing must
immediately be performed on the
associated membrane units as specified
in paragraphs (b)(3)(i) through (v) of this
section.
(c) Second stage filtration. Systems
receive 0.5-log Cryptosporidium
treatment credit for a separate second
stage of filtration that consists of sand,
dual media, GAG. or other fine grain
media following granular media
filtration if the State approves. To be
eligible for this credit, the first stage of
filtration must be preceded by a
coagulation step and both filtration
stages must treat the entire plant flow
taken from a surface water or GWUDI
source. A cap, such as GAG, on a single
stage of filtration is not eligible for this
credit. The State must approve the
treatment credit based on an assessment
of the design characteristics of the
filtration process.
(d) Slow sand filtration (as secondary
filter). Systems are eligible to receive
2.5-log Cryptosporidium treatment
credit for a slow sand filtration process
that follows a separate stage of filtration
if both filtration stages treat entire plant
flow taken from a surface water or
GWUDI source and no disinfectant
residual is present in the influent water
to the slow sand filtration process. The
State must approve the treatment credit
based on an assessment of the design
characteristics of the filtration process.
This paragraph does not apply to
treatment credit awarded to slow sand
filtration used as a primary filtration
process.
§141.720 Inactivation toolbox
components.
(a) Calculation of CT values. (1) CT is
the product of the disinfectant contact
time (T, in minutes) and disinfectant
concentration (C, in milligrams per
liter). Systems with treatment credit for
chlorine dioxide or ozone under
paragraph (b) or (c) of this section must
calculate CT at least once each day, with
both C and T measured during peak
hourly flow as specified in §§ 141.74(a)
through (b).
[2) Systems with several disinfection
segments in sequence may calculate CT
for each segment, where a disinfection
segment is defined as a treatment unit
process with a measurable disinfectant
residual level and a liquid volume.
Under this approach, systems must add
the Cryptosporidium CT values in each
segment to determine the total CT for
the treatment plant.
(b) CT vanies for chlorine dioxide and
ozone. (I) Systems receive the
Cryptosporidium treatment credit listed
in this table by meeting the
corresponding chlorine dioxide CT
value for the applicable water
temperature, as described in paragraph
(a) of this section.
CT VALUES (MG-MIN/L) FOR Cryptosporidium INACTIVATION BY CHLORINE DIOXIDE
Log credit
(j) 025
(h) 05 ...
(iii) 1 0
(iv) 1 5
(v) 20
(vi) 2.5
Water Temperature, °C
<=0.5
159
319
637
956
1275
1594
1
153
305
610
915
1220
1525
2
140
279
558
838
1117
1396
3
128
256
511
767
1023
1278
5
107
214
429
643
858
1072
7
90
180
360
539
719
899
10
69
138
277
415
553
691
15
45
89
179
268
357
447
20
29
58
116
174
232
289
25
19
38
75
113
150
188
30
12
24
49
73
98
122
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Federal Register/Vol. 71, No, 3/Thursday, January 5, 2006/Rules and Regulations
783
CT VALUES (MG-MIN/L) FOR Cryptosporidium INACTIVATION BY CHLORINE DIOXIDE 1—Continued
Log credit
(vii) 3.0
Water Temperature, °C
<=0.5
1912
1
1830
2
1675
3
1534
5
1286
7
1079
10
830
15
536
20
347
25
226
30
147
1 Systems may use this equation to determine log credit between the indicated values Log credit = (0.001506 x (1 09116)Temi>) x CT.
(2) Systems receive the corresponding ozone CT values for the
Cryptosporidium treatment credit listed applicable water temperature, as
in this table by meeting the
described in paragraph (a) of this
section.
CT VALUES (MG-MIN/L) FOR Cryptosporidium INACTIVATION BY OZONE "
Log credit
(i) 025
(ii) 0.5
(ni) 1 0
(iv) 1 5
(v) 2 0
(vi) 2 5
(vii) 3 0
Water Temperature, °C
<=0.5
6.0
12
24
36
48
60
72
1
5.8
12
23
35
46
58
69
2
5.2
10
21
31
42
52
63
3
48
9.5
19
29
38
48
57
5
40
7.9
16
24
32
40
47
7
3.3
6.5
13
20
26
33
39
10
2.5
4.9
9.9
15
20
25
30
15
1.6
31
6.2
9.3
12
16
19
20
1.0
2.0
3.9
5.9
7.8
9.8
12
25
0.6
1.2
2.5
3.7
49
6.2
7.4
30
0.39
0.78
1.6
24
3.1
39
4.7
1 Systems may use this equation to determine log credit between the indicated values Log credit = (0.0397 x (1.09757) |C™P) x CT.
(c) Site-specific study. The State may
approve alternative chlorine dioxide or
ozone CT values to those listed in
paragraph (b) of this section on a site-
specific basis. The State must base this
approval on a site-specific study a
system conducts that follows a State-
approved protocol.
(d) Ultraviolet light. Systems receive
Cryptosporidium. Giardia lamblia, and
virus treatment credits for ultraviolet
(UV) light reactors by achieving the
corresponding UV dose values shown in
paragraph (d)(l) of this section. Systems
must validate and monitor UV reactors
as described in paragraphs (d)(2) and (3)
of this section to demonstrate that they
are achieving a particular UV dose value
for treatment credit.
(1) UVdose table. The treatment
credits listed in this table are for UV
light at a wavelength of 254 nm as
produced by a low pressure mercury
vapor lamp. To receive treatment credit
for other lamp types, systems must
demonstrate an equivalent germicidal
dose through reactor validation testing,
as described in paragraph (d)(2) of this
section. The UV dose values in this
table are applicable only to post-filter
applications of UVin filtered systems
and to unfiltered systems.
UV DOSE TABLE FOR Cryptosporidium, Giardia lamblia, AND VIRUS INACTIVATION CREDIT
Log credit
(i) 05
(n) 1 o
(iii) 1 5 ..
dv) 2 0 ...
(v) 2.5
(vi) 3 0
(vii) 3 5
(vili) 4 0 ...
Cryptosporidium
UV dose (mJ/cm2)
1 6
2.5
3 9
5 8
8.5
12
15
22
Giardia lamblia
UV dose (mJ/cm2)
1 5
2 1
30
5.2
7.7
11
15
22
Virus
UV dose (mJ/cm2)
39
58
79
100
121
143
163
186
(2) Reactor validation testing. Systems
must use UV reactors that have
undergone validation testing to
determine the operating conditions
under which the reactor delivers the UV
dose required in paragraph (d)(l) of this
section (i.e., validated operating
conditions). These operating conditions
must include flow rate, UV intensity as
measured by a UV sensor, and UV lamp
status.
(i) When determining validated
operating conditions, systems must
account for the following factors: UV
absorbance of the water; lamp fouling
and aging; measurement uncertainty of
on-line sensors; UV dose distributions
arising from the velocity profiles
through the reactor; failure of UV lamps
or other critical system components;
and inlet and outlet piping or channel
configurations of the UV reactor.
(ii) Validation testing must include
the following; Full scale testing of a
reactor that conforms uniformly to the
UV reactors used by the system and
inactivation of a test microorganism
whose dose response characteristics
have been quantified with a low
pressure mercury vapor lamp.
(iii) The State may approve an
alternative approach to validation
testing.
(3) Reactor monitoring, (i) Systems
must monitor their UV reactors to
determine if the reactors are operating
within validated conditions, as
determined under paragraph (d)(2) of
this section. This monitoring must
include UV intensity as measured by a
UV sensor, flow rate, lamp status, and
other parameters the State designates
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
based on UV reactor operation. Systems
must verify the calibration of UV
sensors and must recalibrate sensors in
accordance with a protocol the State
approves.
(ii) To receive treatment credit for UV
light, systems must treat at least 95
percent of the water delivered to the
public during each month by UV
reactors operating within validated
conditions for the required UV dose, as
described in paragraphs (d)(l) and (2) of
this section. Systems must demonstrate
compliance with this condition by the
monitoring required under paragraph
(d)(3)(i) of this section.
Reporting and Recordkeeping
Requirements
§141.721 Reporting requirements.
(a) Systems must report sampling
schedules under § 141.702 and source
water monitoring results under
§ 141.706 unless they notify the State
that they will not conduct source water
monitoring due to meeting the criteria of
§141.701(d).
(b) Systems must report the use of
uncovered finished water storage
facilities to the State as described in
§141.714.
(c) Filtered systems must report their
Cryptosporidium bin classification as
described in §141.710.
(d) Unfiltered systems must report
their mean source water
Crvptosporidium level as described in
§141.712.
(e) Systems must report disinfection
profiles and benchmarks to the State as
described in §§ 141:708 through 141.709
prior to making a significant change in
disinfection practice.
(f) Systems must report to the State in
accordance with the following table for
any microbial toolbox options used to
comply with treatment requirements
under §141.711 or §141.712.
Alternatively, the State may approve a
system to certify operation within
required parameters for treatment credit
rather than reporting monthly
operational data for toolbox options.
MICROBIAL TOOLBOX REPORTING REQUIREMENTS
Toolbox option
Systems must submit the following information
On the following schedule
(1) Watershed control pro-
gram (WCP)
(2) Alternative source/intake
management
(3) Presedimentation
(4) Two-stage lime softening
(5) Bank filtration .
(6) Combined filter perform-
ance
(7) Individual filter perform-
ance.
(8) Demonstration of per-
formance.
(i) Notice of intention to develop a new or continue an
existing watershed control program
(n) Watershed control plan
(m) Annual watershed control program status report ....
(iv) Watershed sanitary survey report
Verification that system has relocated the intake or
adopted the intake withdrawal procedure reflected in
monitoring results.
Monthly verification of the following- (i) Continuous
basin operation (ii) Treatment of 100% of the flow (iii)
Continuous addition of a coagulant (iv) At least 0.5-
log mean reduction of influent turbidity or compliance
with alternative State-approved performance criteria.
Monthly verification of the following: (i) Chemical addi-
tion and hardness precipitation occurred in two sepa-
rate and sequential softening stages prior to filtration
(ii) Both stages treated 100% of the plant flow
(i) Initial demonstration of the following- (A) Unconsoli-
dated, predominantly sandy aquifer (B) Setback dis-
tance of at least 25 ft (0.5-log credit) or 50 ft. (1.0-
log credit).
(ii) If monthly average of daily max turbidity is greater
than 1 NTU then system must report result and sub-
mit an assessment of the cause.
Monthly verification of combined filter effluent (CFE)
turbidity levels less than or equal to 0.15 NTU in at
least 95 percent of the 4 hour CFE measurements
taken each month.
Monthly verification of the following (i) Individual filter
effluent (IFE ) turbidity levels less than or equal to
0.15 NTU in at least 95 percent of samples each
month in each filter (ii) No individual filter greater
than 0.3 NTU in two consecutive readings 15 min-
utes apart
(i) Results from testing following a State approved pro-
tocol.
(ii) As required by the State, monthly verification of op-
eration within conditions of State approval for dem-
onstration of performance credit.
No later than two years before the applicable treatment
compliance date in § 141 713
No later than one year before the applicable treatment
compliance date in §141.713
Every 12 months, beginning one year after the applica-
ble treatment compliance date in § 141.713.
For community water systems, every three years begin-
ning three years after the applicable treatment com-
pliance date in §141.713. For noncommunity water
systems, every five years beginning five years after
the applicable treatment compliance date in
§141.713
No later than the applicable treatment compliance date
in §141.713
Monthly reporting within 10 days following the month in
which the monitoring was conducted, beginning on
the applicable treatment compliance date in
§141.713.
Monthly reporting within 10 days following the month in
which the monitoring was conducted, beginning on
the applicable treatment compliance date in
§141.713
No later than the applicable treatment compliance date
in §141 713.
Report within 30 days following the month in which the
monitoring was conducted, beginning on the applica-
ble treatment compliance date in § 141 713.
Monthly reporting within 10 days following the month in
which the monitoring was conducted, beginning on
the applicable treatment compliance date in
§141.713.
Monthly reporting within 10 days following the month in
which the monitoring was conducted, beginning on
the applicable treatment compliance date in
§141.713.]
No later than the applicable treatment compliance date
in §141 713.
Within 10 days following the month in which monitoring
was conducted, beginning on the applicable treat-
ment compliance date in § 141.713
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Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
785
MICROBIAL TOOLBOX REPORTING REQUIREMENTS—Continued
Toolbox option
Systems must submit the following information
On the following schedule
(9) Bag filters and cartridge
filters.
(10) Membrane filtration
(11) Second stage filtration
(12) Slow sand filtration (as
secondary filter).
(13) Chlorine dioxide
(14) Ozone
(15) UV
(i) Demonstration that the following criteria are met (A)
Process meets the definition of bag or cartridge filtra-
tion; (B) Removal efficiency established through chal-
lenge testing that meets criteria in this subpart.
(ii) Monthly verification that 100% of plant flow was fil-
tered.
(i) Results of verification testing demonstrating the fol-
lowing. (A) Removal efficiency established through
challenge testing that meets criteria in this subpart;
(B) Integrity test method and parameters, including
resolution, sensitivity, test frequency, control limits,
and associated baseline.
(n) Monthly report summarizing the following: (A) All di-
rect integrity tests above the control limit; (B) If appli-
cable, any turbidity or alternative state-approved indi-
rect integrity monitoring results triggering direct integ-
rity testing and the corrective action that was taken
Monthly verification that 100% of flow was filtered
through both stages and that first stage was pre-
ceded by coagulation step
Monthly verification that both a slow sand filter and a
preceding separate stage of filtration treated 100% of
flow from subpart H sources..
Summary of CT values for each day as described in
§141.720..
Summary of CT values for each day as described in
§141.720.
(i) Validation test results demonstrating operating condi-
tions that achieve required UV dose.
(ii) Monthly report summarizing the percentage of water
entering the distribution system that was not treated
by UV reactors operating within validated conditions
for the required dose as specified in 141.720(d).
No later than the applicable treatment compliance date
in §141.713.
Within 10 days following the month in which monitoring
was conducted, beginning on the applicable treat-
ment compliance date in § 141.713.
No later than the applicable treatment compliance date
in §141.713
Within 10 days following the month in which monitoring
was conducted, beginning on the applicable treat-
ment compliance date in § 141.713.
Within 10 days following the month in which monitoring
was conducted, beginning on the applicable treat-
ment compliance date in §141.713.
Within 10 days following the month in which monitoring
was conducted, beginning on the applicable treat-
ment compliance date in § 141.713
Within 10 days following the month in which monitoring
was conducted, beginning on the applicable treat-
ment compliance date in § 141.713
Within 10 days following the month in which monitoring
was conducted, beginning on the applicable treat-
ment compliance date in §141.713.
No later than the applicable treatment compliance date
in §141.713.
Within 10 days following the month in which monitoring
was conducted, beginning on the applicable treat-
ment compliance date in § 141 713
§141.722 Recordkeeping requirements.
(a) Systems must keep results from
the initial round of source water
monitoring under § 141.701(a) and the
second round of source water
monitoring under § 141.701[b) until 3
years after bin classification under
§ 141.710 for filtered systems or
determination of the mean
Cryptosporidium level under § 141.710
for unfiltered systems for the particular
round of monitoring.
(b) Systems must keep any
notification to the State that they will
not conduct source water monitoring
due to meeting the criteria of
§141.701(d) for 3 years.
(c) Systems must keep the results of
treatment monitoring associated with
microbial toolbox options under
§§ 141.716 through 141.720 and with
uncovered finished water reservoirs
under § 141.714, as applicable, for 3
years.
Requirements for Sanitary Surveys
Performed by EPA
§141.723 Requirements to respond to
significant deficiencies identified in sanitary
surveys performed by EPA.
(a) A sanitary survey is an onsite
review of the water source (identifying
sources of contamination by using
results of source water assessments
where available), facilities, equipment,
operation, maintenance, and monitoring
compliance of a PWS to evaluate the
adequacy of the PWS, its sources and
operations, and the distribution of safe
drinking water.
(b) For the purposes of this section, a
significant deficiency includes a defect
in design, operation, or maintenance, or
a failure or malfunction of the sources,
treatment, storage, or distribution
system that EPA determines to be
causing, or has the potential for causing
the introduction of contamination into
the water delivered to consumers.
(c) For sanitary surveys performed by
EPA, systems must respond in writing
to significant deficiencies identified in
sanitary survey reports no later than 45
days after receipt of the report,
indicating how and on what schedule
the system will address significant
deficiencies noted in the survey.
(d) Systems must correct significant
deficiencies identified in sanitary
survey reports according to the schedule
approved by EPA, or if there is no
approved schedule, according to the
schedule reported under paragraph (c)
of this section if such deficiencies are
within the control of the system.
PART 142—NATIONAL PRIMARY
DRINKING WATER REGULATIONS
IMPLEMENTATION
• 8. The authority citation for part 142
continues to read as follows:
Authority: 42 U.S.C. 300f, 300g-l, 300g-2,
300g-3, 300g-4, 300g-5, 300g-6, 300J-4. 300J-
9 and 300J-11.
• 9. Section 142.14 is amended by
adding paragraph (a)(9) to read as
follows:
§ 142.14 Records kept by States.
(a)* *
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786
Federal Register/Vol. 71, No. 3/Thursday, January 5, 2006/Rules and Regulations
(9) Any decisions made pursuant to
the provisions of part 141, subpart W of
this chapter.
(i) Results of source water E. coli and
Cryptosporidium monitoring.
(ii) The bin classification after the
initial and after the second round of
source water monitoring for each
filtered system, as described in
§ 141.710 of this chapter.
(iii) Any change in treatment
requirements for filtered systems due to
watershed assessment during sanitary
surveys, as described in § 141.711(d) of
this chapter.
(iv) The determination of whether the
mean Cryptosporidium level is greater
than 0.01 oocysts/L after the initial and
after the second round of source water
monitoring for each unfiltered system,
as described in § 141.712(a) of this
chapter.
(v) The treatment processes or control
measures that systems use to meet their
Cryptosporidium treatment
requirements under § 141.711 or
§ 141.712 of this chapter.
(vi) A list of systems required to cover
or treat the effluent of an uncovered
finished water storage facility, as
specified in § 141.714 of this chapter.
*****
• 10. Section 142.15 is amended by
adding paragraph (c)(6) to read as
follows:
§ 142.15 Reports by States.
(c) * * *
(6) Subpart W. (i) The bin
classification after the initial and after
the second round of source water
monitoring for each filtered system, as
described in § 141.710 of this chapter.
(ii) Any change in treatment
requirements for these systems due to
watershed assessment during sanitary
surveys, as described in §141.711(d) of
this chapter.
(iii} The determination of whether the
mean Cryptospondium level is greater
than 0.01 oocysts/L both after the initial
and after the second round of source
water monitoring for each unfiltered
system, as described in § 141.712(a) of
this chapter.
*****
• 11. Section 142.16 is amended by
adding paragraph (n) to read as follows:
§ 142.16 Special primacy conditions.
*****
(n) Requirements for States to adopt
40 CFRpart 141, subpart W. In addition
to the general primacy requirements
elsewhere in this part, including the
requirements that State regulations be at
least as stringent as Federal
requirements, an application for
approval of a State program revision
that adopts 40 CFR part 141, subpart W,
must contain a description of how the
State will accomplish the following
program requirements where allowed in
State programs.
(1) Approve an alternative to the E.
coli levels that trigger Cryptosporidium
monitoring by filtered systems serving
fewer than 10,000 people, as described
in§141.701(a)(5).
(2) Assess significant changes in the
watershed and source water as part of
the sanitary survey process and
determine appropriate follow-up action
for systems, as described in § 141.711(d)
of this chapter.
(3) Approve watershed control
programs for the 0.5-log treatment credit
in the microbial toolbox, as described in
§ 141.716(a) of this chapter.
(4) Approve protocols for
demonstration of performance treatment
credits in the microbial toolbox, as
allowed under § 141.718(c) of this
chapter.
(5) Approve protocols for alternative
ozone and chlorine dioxide CT values in
the microbial toolbox, as allowed under
§141.720(c) of this chapter.
(6) Approve an alternative approach
to UV reactor validation testing in the
microbial toolbox, as allowed under
§141.720(d)(2)(iii) of this chapter.
*****
|FR Doc. 06-4 Filed 1-4-06; 8:45 am]
BILLING CODE 6560-50-P
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