[Federal Register Volume 65, Number 69 (Monday, April 10, 2000)]
[Proposed Rules]
[Pages 19046-19150]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-8155]



[[Page 19045]]

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Part II





Environmental Protection Agency





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40 CFR Parts 141 and 142



National Primary Drinking Water Regulations: Long Term 1 Enhanced 
Surface Water Treatment and Filter Backwash Rule; Proposed Rule

  Federal Register / Vol. 65, No. 69 / Monday, April 10, 2000 / 
Proposed Rules  

[[Page 19046]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 141 and 142

[WH-FRL-6570-5]
RIN 2040-AD18


National Primary Drinking Water Regulations: Long Term 1 Enhanced 
Surface Water Treatment and Filter Backwash Rule

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: In this document, EPA is proposing the Long Term 1 Enhanced 
Surface Water Treatment and Filter Backwash Rule (LT1FBR). The purposes 
of the LT1FBR are to: Improve control of microbial pathogens in 
drinking water, including Cryptosporidium, for public water systems 
(PWSs) serving fewer than 10,000 people; prevent increases in microbial 
risk while PWSs serving fewer than 10,000 people control for 
disinfection byproducts, and; require certain PWSs to institute changes 
to the return of recycle flows within the treatment process to reduce 
the effects of recycle on compromising microbial control. Today's 
proposal addresses two statutory requirements of the 1996 Safe Drinking 
Water Act (SDWA) Amendments. First, it addresses the statutory 
requirement to establish a Long Term Final Enhanced Surface Water 
Treatment Rule (LTESWTR) for PWSs that serve under 10,000 people. 
Second, it addresses the statutory requirement to promulgate a 
regulation which ``governs'' the recycle of filter backwash within the 
treatment process of public utilities.
    Today's proposed LT1FBR contains 5 key provisions for surface water 
and ground water under the direct influence of surface water (GWUDI) 
systems serving fewer than 10,000 people: A treatment technique 
requiring a 2-log (99 percent) Cryptosporidium removal requirement; 
strengthened combined filter effluent turbidity performance standards 
and new individual filter turbidity provisions; disinfection benchmark 
provisions to assure continued microbial protection is provided while 
facilities take the necessary steps to comply with new disinfection 
byproduct standards; inclusion of Cryptosporidium in the definition of 
GWUDI and in the watershed control requirements for unfiltered public 
water systems; and requirements for covers on new finished water 
reservoirs.
    Today's proposed LT1FBR contains three key provisions for all 
conventional and direct filtration systems which recycle and use 
surface water or GWUDI: A provision requiring recycle flows to be 
introduced prior to the point of primary coagulant addition; a 
requirement for systems meeting criteria to perform a one-time self 
assessment of their recycle practice and consult with their primacy 
agency to address and correct high risk recycle operations; and a 
requirement for direct filtration systems to provide information to the 
State on their current recycle practice.
    The Agency believes implementing the provisions contained in 
today's proposal will improve public health protection in two 
fundamental ways. First, the provisions will reduce the level of 
Cryptosporidium in filtered finished drinking water supplies through 
improvements in filtration and recycle practice resulting in a reduced 
likelihood of outbreaks of cryptosporidiosis. Second, the filtration 
provisions are expected to increase the level of protection from 
exposure to other pathogens (i.e. Giardia or other waterborne bacterial 
or viral pathogens). It is also important to note that while today's 
proposed rule contains new provisions which in some cases strengthen or 
modify requirements of the 1989 Surface Water Treatment Rule, each 
public water system must continue to comply with the current rules 
while new microbial and disinfectants/disinfection byproducts rules are 
being developed. In conjunction with the Maximum Contaminant Level Goal 
(MCLG) established in the Interim Enhanced Surface Water Treatment 
Rule, the Agency developed a treatment technique in lieu of a Maximum 
Contaminant Level (MCL) for Cryptosporidium because it is not 
economically and technologically feasible to accurately ascertain the 
level of Cryptosporidium using current analytical methods.

DATES: The Agency requests comments on today's proposal. Comments must 
be received or post-marked by midnight June 9, 2000. Comments received 
after this date may not be considered in decision making on the 
proposed rule.

ADDRESSES: Send written comments on today's proposed rule to the LT1FBR 
Comment Clerk: Water Docket MC 410, W-99-10, Environmental Protection 
Agency 401 M Street, S.W., Washington, DC 20460. Please submit an 
original and three copies of comments and enclosures (including 
references).
    Those who comment and want EPA to acknowledge receipt of their 
comments must enclose a self-addressed stamped envelope. No facsimiles 
(faxes) will be accepted. Comments may also be submitted electronically 
to [email protected]. For additional information on submitting 
electronic comments see Supplementary Information Section.
    Public comments on today's proposal, other major supporting 
documents, and a copy of the index to the public docket for this 
rulemaking are available for review at EPA's Office of Water Docket: 
401 M Street, SW., Rm. EB57, Washington, DC 20460 from 9:00 a.m. to 
4:00 p.m., Eastern Time, Monday through Friday, excluding legal 
holidays. For access to docket materials or to schedule an appointment 
please call (202) 260-3027.

FOR FURTHER INFORMATION CONTACT: Technical inquiries on the rule should 
be directed to Jeffery Robichaud at 401 M Street, SW., MC4607, 
Washington, DC 20460 or (202) 260-2568. For general information contact 
the Safe Drinking Water Hotline, Telephone (800) 426-4791. The Safe 
Drinking Water Hotline is open Monday through Friday, excluding federal 
holidays, from 9:00 a.m. to 5:30 p.m. Eastern Time.

SUPPLEMENTARY INFORMATION: Entities potentially regulated by the LT1FBR 
are public water systems (PWSs) that use surface water or ground water 
under the direct influence of surface water (GWUDI). The recycle 
control provisions are applicable to all PWSs using surface water or 
GWUDI, regardless of the population served. All other provisions of the 
LT1FBR are only applicable to PWSs serving under 10,000 people. 
Regulated categories and entities include:

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           Category                  Examples of regulated entities
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Industry.....................  Public Water Systems that use surface
                                water or ground water under the direct
                                influence of surface water.
State, Local, Tribal or        Public Water Systems that use surface
 Federal Governments.           water or ground water under the direct
                                influence of surface water.
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    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by the 
LT1FBR. This table lists the types of entities that EPA is now aware 
could potentially be regulated by this rule. 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 Sec. 141.3 of the Code of 
Federal Regulations and applicability criteria in Secs. 141.76 and 
141.501 of today's proposal. If you have questions regarding the 
applicability of the LT1FBR to a particular entity, consult the person 
listed in the preceding section entitled FOR FURTHER INFORMATION 
CONTACT.

Submitting Comments

    Send an original and three copies of your comments and enclosures 
(including references) to W-99-10 Comment Clerk, Water Docket (MC4101), 
USEPA, 401 M Street, SW., Washington, D.C. 20460. Comments must be 
received or post-marked by midnight June 9, 2000. Note that the Agency 
is not soliciting comment on, nor will it respond to, comments on 
previously published regulatory language that is included in this 
document to ease the reader's understanding of the proposed language.
    To ensure that EPA can read, understand and therefore properly 
respond to comments, the Agency would prefer that commenters cite, 
where possible, the paragraph(s) or sections in the proposed rule or 
supporting documents to which each comment refers. Commenters should 
use a separate paragraph for each issue discussed.

Electronic Comments

    Comments may also be submitted electronically to [email protected]. Electronic comments must be submitted as an 
ASCII, WP5.1, WP6.1 or WP8 file avoiding the use of special characters 
and form of encryption. Electronic comments must be identified by the 
docket number W-99-10. Comments and data will also be accepted on disks 
in WP 5.1, 6.1, 8 or ASCII file format. Electronic comments on this 
document may be filed online at many Federal Depository Libraries.
    The record for this rulemaking has been established under docket 
number W-99-10, and includes supporting documentation as well as 
printed, paper versions of electronic comments. The record is available 
for inspection from 9 a.m. to 4 p.m., Monday through Friday, excluding 
legal holidays at the Water Docket, EB 57, USEPA Headquarters, 401 M 
Street, SW., Washington, D.C. For access to docket materials, please 
call (202) 260-3027 to schedule an appointment.
List of Abbreviations Used in This Document
ASCE  American Society of Civil Engineers
ASDWA  Association of State Drinking Water Administrators
ASTM  American Society for Testing Materials
AWWA  American Water Works Association
AWWARF  American Water Works Association Research Foundation
 deg.C  Degrees Centigrade
CCP  Composite Correction Program
CDC  Centers for Disease Control
CFE  Combined Filter Effluent
CFR  Code of Federal Regulations
COI  Cost of Illness
CPE   Comprehensive Performance Evaluation
CT  The Residual Concentration of Disinfectant (mg/L) Multiplied by the 
Contact Time (in minutes)
CTA  Comprehensive Technical Assistance
CWSS  Community Water System Survey
DBPs  Disinfection Byproducts
DBPR  Disinfectants/Disinfection Byproducts Rule
ESWTR  Enhanced Surface Water Treatment Rule
FACA  Federal Advisory Committee Act
GAC   Granular Activated Carbon
GAO  Government Accounting Office
GWUDI  Ground Water Under the Direct Influence of Surface Water
HAA5  Haloacetic acids (Monochloroacetic, Dichloroacetic, 
Trichloroacetic, Monobromoacetic and Dibromoacetic Acids)
HPC  Heterotropic Plate Count
hrs  Hours
ICR  Information Collection Rule
IESWTR  Interim Enhanced Surface Water Treatment Rule
IFA  Immunofluorescence Assay
Log Inactivation  Logarithm of (No/NT)
Log  Logarithm (common, base 10)
LTESWTR  Long Term Enhanced Surface Water Treatment Rule
LT1FBR  Long Term 1 Enhanced Surface Water Treatment and Filter 
Backwash Rule
MCL  Maximum Contaminant Level
MCLG  Maximum Contaminant Level Goal
MGD  Million Gallons per Day
M-DBP  Microbial and Disinfectants/Disinfection Byproducts
MPA  Microscopic Particulate Analysis
NODA  Notice of Data Availability
NPDWR  National Primary Drinking Water Regulation
NT  The Concentration of Surviving Microorganisms at Time T
NTTAA  National Technology Transfer and Advancement Act
NTU  Nephelometric Turbidity Unit
PE  Performance Evaluation
PWS  Public Water System
Reg. Neg.  Regulatory Negotiation
RIA  Regulatory Impact Analysis
RFA  Regulatory Flexibility Act
RSD  Relative Standard Deviation
SAB  Science Advisory Board
SDWA  Safe Drinking Water Act
SWTR  Surface Water Treatment Rule
TC  Total Coliforms
TCR  Total Coliform Rule
TTHM  Total Trihalomethanes
TWG  Technical Work Group
TWS  Transient Non-Community Water System
UMRA  Unfunded Mandates Reform Act
URCIS  Unregulated Contaminant Information System
x log removal  Reduction to 1/10\x\ of original concentration

Table of Contents

I. Introduction and Background

A. Statutory Requirements and Legal Authority
B. Existing Regulations and Stakeholder Involvement
    1. 1979 Total Trihalomethane Rule
    2. Total Coliform Rule
    3. Surface Water Treatment Rule
    4. Information Collection Rule
    5. Interim Enhanced Surface Water Treatment Rule
    6. Stage 1 Disinfectants and Disinfection Byproduct Rule
    7. Stakeholder Involvement

II. Public Health Risk

A. Introduction
B. Health Effects of Cryptosporidiosis and Sources and Transmission 
of Cryptosporidium
C. Waterborne Disease Outbreaks In the United States
D. Source Water Occurrence Studies
E. Filter Backwash and Other Process Streams: Occurrence and Impact 
Studies
F. Summary and Conclusions

III. Baseline Information-Systems Potentially Affected By Today's 
Proposed Rule

IV. Discussion of Proposed LT1FBR Requirements

A. Enhanced Filtration Requirements
    1. Two Log Cryptosporidium Removal Requirement
    a. Two Log Removal
    i. Overview and Purpose
    ii. Data
    iii. Proposed Requirements
    iv. Request for Comments
    2. Turbidity Requirements
    a. Combined Filter Effluent

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    i. Overview and Purpose
    ii. Data
    iii. Proposed Requirements
    iv. Request for Comments
    b. Individual Filter Turbidity
    i. Overview and Purpose
    ii. Data
    iii. Proposed Requirements
    iv. Request for Comments
B. Disinfection Benchmarking Requirements
    1. Applicability Monitoring
    a. Overview and Purpose
    b. Data
    c. Proposed Requirements
    d. Request for Comment
    2. Disinfection Profiling
    a. Overview and Purpose
    b. Data
    c. Proposed Requirements
    d. Request for Comments
    3. Disinfection Benchmarking
    a. Overview and Purpose
    b. Data
    c. Proposed Requirements
    d. Request for Comments

C. Additional Requirements

1. Inclusion of Cryptosporidium In Definition of GWUDI
    a. Overview and Purpose
    b. Data
    c. Proposed Requirements
    d. Request for Comments
2. Inclusion of Cryptosporidium Watershed Requirements for 
Unfiltered Systems
    a. Overview and Purpose
    b. Data
    c. Proposed Requirements
    d. Request for Comments
3. Requirements for Covering New Reservoirs
    a. Overview and Purpose
    b. Data
    c. Proposed Requirements
    d. Request for Comments
    D. Recycle Provisions for Public Water Systems Employing Rapid 
Granular Filtration Using Surface Water and GWUDI as a Source
    1. Treatment Processes that Commonly Recycle and Recycle Flow 
Occurrence Data
    a. Treatment Processes that Commonly Recycle
    i. Conventional Treatment Plants
    ii. Direct Filtration Plants
    iii. Softening Plants
    iv. Contact Clarification Plants
    v. Package Plants
    vi. Summary of Recycle Disposal Options
    b. Recycle Flow Occurrence Data
    i. Untreated Spent Filter Backwash Water
    ii. Gravity Settled Spent Filter Backwash Water
    iii. Combined Gravity Thickener Supernatant
    iv. Gravity Thickener Supernatant from Sedimentation Solids
    v. Mechanical Dewatering Device Liquids
    2. National Recycle Practices
    a. Information Collection Rule
    i. Recycle Practice
    b. Recycle FAX Survey
    i. Recycle practice
    ii. Options to recycle
    iii. Conclusions
    3. Recycle Provisions for PWSs Employing Rapid Granular 
Filtration Using Surface Water or Ground Water Under the Direct 
Influence of Surface Water Influence of Surface Water
    a. Return Select Recycle Streams Prior to the Point of Primary 
Coagulant Addition
    i. Overview and Purpose
    ii. Data
    iii. Proposed Requirements
    iv. Request for Comments
    b. Recycle Requirements for Systems Practicing Direct Recycle 
and Meeting Specific Criteria
    i. Overview and Purpose
    ii. Data
    iii. Proposed Requirements
    iv. Request for Comments
    c. Requirements for Direct Filtration Plants that Recycle Using 
Surface Water or GWUDI
    i. Overview and Purpose
    ii. Data
iii. Proposed Requirements
iv. Request for Comments
d. Request for Additional Comment

V. State Implementation and Compliance Schedules

A. Special State Primacy Requirements
B. State Recordkeeping Requirements
C. State Reporting Requirements
D. Interim Primacy
E. Compliance Deadlines

VI. Economic Analysis

A. Overview
B. Quantifiable and Non-Quantifiable Costs
    1. Total Annual Costs
    2. Annual Costs of Rule Provisions
    3. Non Quantifiable Costs
C. Quantifiable and Non-Quantifiable Health Benefits
    1. Quantified Health Benefits
    2. Non-Quantified Health and Non-Health Related Benefits
    a. Recycle Provisions
    b. Issues Associated with Unquantified Benefits
D. Incremental Costs and Benefits
E. Impacts on Households
F. Benefits From the Reduction of Co-Occurring Contaminants
G. Risk Increases From Other Contaminants
H. Other Factors: Uncertainty in Risk, Benefits, and Cost Estimates
I. Benefit Cost Determination
J. Request for Comment

VII. Other Requirements

A. Regulatory Flexibility Act
    1. Today's Proposed Rule
    2. Use of Alternative Definition
    3. Background and Analysis
    a. Number of Small Entities Affected
    b. Recordkeeping and Reporting
    c. Interaction with Other Federal Rules
    d. Significant Alternatives
    i. Turbidity Provisions
    ii. Disinfection Benchmarking Applicability Monitoring 
Provisions
    iii. Recycling Provisions
    e. Other Comments
B. Paperwork Reduction Act
C. Unfunded Mandates Reform Act
    1. Summary of UMRA requirements
    2. Written Statement for Rules With Federal Mandates of $100 
Million or More
    a. Authorizing Legislation
    b. Cost Benefit Analysis
    c. Estimates of Future Compliance Costs and Disproportionate 
Budgetary Effects
    d. Macro-economic Effects
    e. Summary of EPA's Consultation with State, Local, and Tribal 
Governments and Their Concerns
    f. Regulatory Alternatives Considered
    g. Selection of the Least Costly, Most-Cost Effective or Least 
Burdensome Alternative That Achieves the Objectives of the Rule
    3. Impacts on Small Governments
D. National Technology Transfer and Advancement Act
E. Executive Order 12866: Regulatory Planning and Review
F. Executive Order 12898: Environmental Justice
G. Executive Order 13045: Protection of Children from Environmental 
Health Risks and Safety Risks
H. Consultations with the Science Advisory Board, National Drinking 
Water Advisory Council, and the Secretary of Health and Human 
Services
I. Executive Order 13132: Executive Orders on Federalism
J. Executive Order 13084: Consultation and Coordination With Indian 
Tribal Governments
K. Likely Effect of Compliance with the LT1FBR on the Technical, 
Financial, and Managerial Capacity of Public Water Systems
L. Plain Language

VIII. Public Comment Procedures

A. Deadlines for Comment
B. Where to Send Comment
C. Guidelines for Commenting

IX. References

I. Introduction and Background

A. Statutory Requirements and Legal Authority

    The Safe Drinking Water Act (SDWA or the Act), as amended in 1986, 
requires U.S. Environmental Protection Agency (EPA) to publish a 
maximum contaminant level goal (MCLG) for each contaminant which, in 
the judgement of the EPA Administrator, ``may have any adverse effect 
on the health of persons and which is known or anticipated to occur in 
public water systems' (Section 1412(b)(3)(A)). MCLGs are to be set at a 
level at which ``no known or anticipated adverse effect on the health 
of persons occur and which allows an adequate margin of safety'' 
(Section 1412(b)(4)).
    The Act was again amended in August 1996, resulting in the 
renumbering and augmentation of certain sections with additional 
statutory language. New sections were added establishing new drinking 
water requirements. These modifications are outlined below.
    The Act requires EPA to publish a National Primary Drinking Water 
Regulation (NPDWR) that specifies

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either a maximum contaminant level (MCL) or treatment technique 
(Sections 1401(1) and 1412(a)(3)) at the same time it publishes an 
MCLG, which is a non-enforceable health goal. EPA is authorized to 
promulgate a 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.'' EPA's general authority to set MCLGs and NPDWRs applies 
to contaminants that may ``have an adverse effect on the health of 
persons,'' that are ``known to occur or there is a substantial 
likelihood that the contaminant will occur in public water systems 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 public water systems'' (SDWA Section 
1412(b)(1)(A)).
    The 1996 amendments, also require EPA, when proposing a NPDWR that 
includes an MCL or treatment technique, to publish and seek public 
comment on an analysis of health risk reduction and cost impacts. EPA 
is required to take into consideration the effects of contaminants upon 
sensitive subpopulations (i.e., infants, children, pregnant women, the 
elderly, and individuals with a history of serious illness), and other 
relevant factors (Section 1412(b)(3)(C)).
    The amendments established a number of regulatory deadlines, 
including schedules for a Stage 1 Disinfection Byproduct Rule (DBPR), 
an Interim Enhanced Surface Water Treatment Rule (IESWTR), a Long Term 
Final Enhanced Surface Water Treatment Rule (LTESWTR), and a Stage 2 
DBPR (Section 1412(b)(2)(C)). To provide additional time for systems 
serving fewer than 10,000 people to comply with the IESWTR provisions 
and also ensure these systems implement Stage 1 DBPR and the IESWTR 
provisions simultaneously, the Agency split the IESWTR into two rules: 
the IESWR and the LT1ESWTR. The Act as amended also requires EPA to 
promulgate regulations to ``govern'' the recycle of filter backwash 
within the treatment process of public utilities (Section 1412(b)(14)).
    Under 1412(b)(4)(E)(ii), EPA must develop a Small System Technology 
List for the LT1FBR. The filtration technologies listed in the Small 
System Compliance Technology List for the Surface Water Treatment Rule 
and Total Coliform Rule (EPA-815-R-98-001, September 1998) are also the 
technologies which would achieve compliance with the provisions of the 
LT1FBR. EPA will develop a separate list for the LT1FBR as new 
technologies become available.
    Although the Act permits small system variances for compliance with 
a requirement of a national primary drinking water regulation which 
specifies a maximum contaminant level or treatment technique, Section 
1415(e)(6)(B) of SDWA, excludes variances for any national primary 
drinking water regulation for a microbial contaminant or an indicator 
or treatment technique for a microbial contaminant. LT1FBR requires 
treatment techniques to control Cryptosporidium (a microbial 
contaminant), and as such systems governed by the LT1FBR are ineligible 
for variances.
    Finally, as part of the 1996 SDWA Amendments, recordkeeping 
requirements were modified to apply to every person who is subject to a 
requirement of this title or who is a grantee (Section 1445(a)(1)(A)). 
Such persons are required to establish and maintain such records, make 
such reports, conduct such monitoring, and provide such information as 
the Administrator may reasonably require by regulation.

B. Existing Regulations and Stakeholder Involvement

1. 1979 Total Trihalomethane Rule
    In November 1979 (44 FR 68624) (EPA, 1979) EPA set an interim MCL 
for total trihalomethanes (TTHM--the sum of chloroform, bromoform, 
bromodichloromethane, dibromochloromethane) of 0.10 mg/l as an annual 
average. Compliance is defined on the basis of a running annual average 
of quarterly averages for four samples taken in the distribution 
system. The value for each sample is the sum of the measured 
concentrations of chloroform, bromodichloromethane, 
dibromochloromethane and bromoform.
    The interim TTHM standard applies to community water systems using 
surface water and/or ground water serving at least 10,000 people that 
add a disinfectant to the drinking water during any part of the 
treatment process. At their discretion, States may extend coverage to 
smaller PWSs; however, most States have not exercised this option. The 
Stage 1 DBPR (as discussed later) contains updated TTHM requirements.
2. Total Coliform Rule
    The Total Coliform Rule (TCR) (54 FR 27544, June 29, 1989) (EPA, 
1989a) applies to all public water systems. The TCR sets compliance 
with the Maximum Contaminant Level (MCL) for total coliforms (TC) as 
follows. For systems that collect 40 or more samples per month, no more 
than 5 percent of the samples may be TC-positive; for those that 
collect fewer than 40 samples, no more than one sample may be TC-
positive. If a system has a TC-positive sample, it must test that 
sample for the presence of fecal coliforms or E. coli. The system must 
also collect a set of repeat samples, and analyze for TC (and fecal 
coliform or E. coli within 24 hours of the first TC-positive sample).
    In addition, any fecal coliform-positive repeat sample, E-coli.-
positive repeat sample, or any total-coliform-positive repeat sample 
following a fecal coliform-positive or E-coli-positive routine sample 
constitutes an acute violation of the MCL for total coliforms. If a 
system exceeds the MCL, it must notify the public using mandatory 
language developed by the EPA. The required monitoring frequency for a 
system depends on the number of people served and ranges from 480 
samples per month for the largest systems to once annually for the 
smallest systems. All systems must have a written plan identifying 
where samples are to be collected.
    The TCR also requires an on-site inspection (referred to as a 
sanitary survey) every 5 years for each system that collects fewer than 
five samples per month. This requirement is extended to every 10 years 
for non-community systems using only protected and disinfected ground 
water.
3. Surface Water Treatment Rule
    Under the Surface Water Treatment Rule (SWTR) (54 FR 27486, June 
29, 1989) (EPA, 1989b), EPA set maximum contaminant level goals of zero 
for Giardia lamblia, viruses, and Legionella and promulgated regulatory 
requirements for all PWSs using surface water sources or ground water 
sources under the direct influence of surface water. The SWTR includes 
treatment technique requirements for filtered and unfiltered systems 
that are intended to protect against the adverse health effects of 
exposure to Giardia lamblia, viruses, and Legionella, as well as many 
other pathogenic organisms. Briefly, those requirements include (1) 
Requirements for maintenance of a disinfectant residual in the 
distribution system; (2) removal and/or inactivation of 3 log (99.9 
percent) for Giardia and 4 log (99.99 percent) for viruses; (3) 
combined filter effluent turbidity performance standard of 5 
nephelometric turbidity units (NTU) as a maximum and 0.5 NTU

[[Page 19050]]

at the 95th percentile monthly, based on 4-hour monitoring for 
treatment plants using conventional treatment or direct filtration 
(with separate standards for other filtration technologies); and (4) 
watershed protection and other requirements for unfiltered systems. 
Systems seeking to avoid filtration were required to meet avoidance 
criteria and obtain avoidance determination by December 30, 1991, 
otherwise filtration must have been provided by June 29, 1993. For 
systems properly avoiding filtration, later failures to meet avoidance 
criteria triggered a requirement that filtration be provided within 18 
months.
4. Information Collection Rule
    The Information Collection Rule (ICR), which was promulgated on May 
14, 1996 (61 FR 24354) (EPA, 1996) applied to large public water 
systems serving populations of 100,000 or more. A more limited set of 
ICR requirements pertain to ground water systems serving between 50,000 
and 100,000 people. About 300 PWSs operating 500 treatment plants were 
involved with the extensive ICR data collection. Under the ICR, these 
PWSs monitored for water quality factors affecting disinfection 
byproduct (DBP) formation and DBPs within the treatment plant and in 
the distribution system on a monthly basis for 18 months. In addition, 
PWSs were required to provide treatment train schematics, operating 
data and source water occurrence data for bacteria, viruses, and 
protozoa. Finally, a subset of PWSs performed treatment studies, using 
either granular activated carbon (GAC) or membrane processes, to 
evaluate DBP precursor removal and control of DBPs. Monitoring for 
treatment study applicability began in September 1996. The remaining 
occurrence monitoring began in July 1997 and concluded in December 
1998.
    The purpose of the ICR was to collect occurrence and treatment 
information to help evaluate the need for possible changes to the 
current microbial requirements and existing microbial treatment 
practices, and to help evaluate the need for future regulation of 
disinfectants and disinfection byproducts (DBPs). The ICR will provide 
EPA with additional information on the national occurrence in drinking 
water of (1) chemical byproducts that form when disinfectants used for 
microbial control react with naturally occurring compounds already 
present in source water; and (2) disease-causing microorganisms, 
including Cryptosporidium, Giardia, and viruses. Analysis of ICR data 
is not expected to be completed in the time frame necessary for 
inclusion in the LT1FBR, however if the data is available and has been 
quality controlled and peer reviewed during the necessary time frame, 
EPA will consider the datat as it refines its analysis for the final 
rule.
    The ICR also required PWSs to provide engineering data on how they 
currently control for such contaminants. The ICR monthly sampling data 
will also provide information on the quality of the recycle waters via 
monthly monitoring (for 18 months) of pH, alkalinity, turbidity, 
temperature, calcium and total hardness, TOC, UV254, 
bromide, ammonia, and disinfectant residual (if disinfectant is used). 
This data will provide some indication of the treatability of the 
water, the extent to which contaminant concentration effects may occur, 
and the potential for contribution to DBP formation. However, sampling 
to determine the occurrence of pathogens in recycle waters was not 
performed.
5. Interim Enhanced Surface Water Treatment Rule
    Public water systems serving 10,000 or more people that use surface 
water or ground water under the direct influence of surface water 
(GWUDI) are required to comply with the IESWTR (63 FR 69477, December 
16, 1998) (EPA, 1998a) by December of 2001. The purposes of the IESWTR 
are to improve control of microbial pathogens, specifically the 
protozoan Cryptosporidium, and address risk trade-offs between 
pathogens and disinfection byproducts. Key provisions established by 
the rule include: a Maximum Contaminant Level Goal (MCLG) of zero for 
Cryptosporidium; 2-log (99 percent) Cryptosporidium removal 
requirements for systems that filter; strengthened combined filter 
effluent turbidity performance standards of 1.0 NTU as a maximum and 
0.3 NTU at the 95th percentile monthly, based on 4-hour monitoring for 
treatment plants using conventional treatment or direct filtration; 
requirements for individual filter turbidity monitoring; disinfection 
benchmark provisions to assess the level of microbial protection 
provided as facilities take the necessary steps to comply with new 
disinfection byproduct standards; inclusion of Cryptosporidium in the 
definition of GWUDI and in the watershed control requirements for 
unfiltered public water systems; requirements for covers on new 
finished water reservoirs; and sanitary surveys for all surface water 
systems regardless of size.
6. Stage 1 Disinfectants and Disinfection Byproduct Rule
    The Stage 1 DBPR applies to all PWSs that are community water 
systems (CWSs) or nontransient noncommunity water systems (NTNCWs) that 
treat their water with a chemical disinfectant for either primary or 
residual treatment. In addition, certain requirements for chlorine 
dioxide apply to transient noncommunity water systems (TNCWSs). The 
Stage 1 DBPR (EPA, 1998c) was published at the same time as the IESWTR 
(63 FR 69477, December 16, 1998) (EPA, 1998a). Surface water and GWUDI 
systems serving at least 10,000 persons are required to comply with the 
Stage 1 Disinfectants and Disinfection Byproducts Rule by December 
2001. Ground water systems and surface water and GWUDI systems serving 
fewer than 10,000 must comply with the Stage 1 Disinfectants and 
Disinfection Byproducts Rule by December 2003.
    The Stage 1 DBPR finalizes maximum residual disinfectant level 
goals (MRDLGs) for chlorine, chloramines, and chlorine dioxide; MCLGs 
for four trihalomethanes (chloroform, bromodichloromethane, 
dibromochloromethane, and bromoform), two haloacetic acids 
(dichloroacetic acid and trichloroacetic acid), bromate, and chlorite; 
and NPDWRs for three disinfectants (chlorine, chloramines, and chlorine 
dioxide), two groups of organic disinfection byproducts TTHMs and HAA5 
and two inorganic disinfection byproducts, chlorite and bromate. The 
NPDWRs consist of maximum residual disinfectant levels (MRDLs) or 
maximum contaminant levels (MCLs) or treatment techniques for these 
disinfectants and their byproducts. The NPDWRs also include monitoring, 
reporting, and public notification requirements for these compounds. 
The Stage 1 DBPR includes the best available technologies (BATs) upon 
which the MRDLs and MCLs are based. EPA believes the implementation of 
the Stage 1 DBPR will reduce the levels of disinfectants and 
disinfection byproducts in drinking water supplies. The Agency believes 
the rule will provide public health protection for an additional 20 
million households that were not previously covered by drinking water 
rules for disinfection byproducts.
7. Stakeholder Involvement
    EPA conducted two stakeholder meetings to solicit feedback and 
information from the regulated community and other concerned 
stakeholders on issues relating to

[[Page 19051]]

today's proposed rule. The first meeting was held July 22 and 23, 1998 
in Lakewood, Colorado. EPA presented potential regulatory components 
for the LT1FBR. Breakout sessions with stakeholders were held to 
generate feedback on the regulatory provisions being considered and to 
solicit feedback on next steps for rule development and stakeholder 
involvement. Additionally, information was presented summarizing 
ongoing research and data gathering activities regarding the recycle of 
filter backwash. The presentations generated useful discussion and 
provided substantial feedback to EPA regarding technical issues, 
stakeholder concerns, and possible regulatory options (EPA 1999k). The 
second stakeholder meeting was held in Dallas, Texas on March 3 and 4, 
1999. EPA presented new analyses, summaries of current research, and 
revised regulatory options and data collected since the July 
stakeholder meeting. Regional perspectives on turbidity and 
disinfection benchmarking components were also discussed with 
presentations from EPA Region VI and the Texas Natural Resources 
Conservation Commission. Four break-out sessions were extremely useful 
and generated a wide range of information, issues, and technical input 
from a diverse group of stakeholders (EPA 1999j).
    The Agency utilized the feedback received during these two 
stakeholder meetings in developing today's proposed rule. EPA also 
mailed a draft version of the preamble for today's proposed rule to the 
attendees of these meetings. Several of the options which are presented 
today represent modifications suggested by stakeholders.

II. Public Health Risk

    The purpose of this section is to discuss the health risk 
associated with pathogens, particularly Cryptosporidium, in surface 
waters and GWUDI. More detailed information about such pathogens and 
other contaminants of concern may be found in an EPA criteria document 
for Giardia (EPA 1998d), three EPA criteria documents for viruses (EPA, 
1985; 1999a; 1999b), the Cryptosporidium and Giardia Occurrence 
Assessment for the Interim Enhanced Surface Water Treatment Rule (EPA, 
1998b) and the LT1FBR Occurrence and Assessment Document (EPA 1999c). 
EPA requests comment on today's proposed rule, the information 
supporting the proposal, and the potential impact of proposed 
regulatory provisions on public health risk.

A. Introduction

    In 1990, EPA's Science Advisory Board (SAB), an independent panel 
of experts established by Congress, cited drinking water contamination 
as one of the most important environmental risks and indicated that 
disease-causing microbial contaminants (i.e., bacteria, protozoa and 
viruses) are probably the greatest remaining health risk management 
challenge for drinking water suppliers (EPA/SAB, 1990). Information on 
the number of waterborne disease outbreaks from the U.S. Centers for 
Disease Control and Prevention (CDC) underscores this concern. CDC 
indicates that, between 1980 and 1996, 401 waterborne disease outbreaks 
were reported, with over 750,000 associated cases of disease. During 
this period, a number of agents were implicated as the cause, including 
protozoa, viruses and bacteria.
    Waterborne disease caused by Cryptosporidium is of particular 
concern, as it is difficult to inactivate Cryptosporidium oocysts with 
standard disinfection practices (unlike pathogens such as viruses and 
bacteria), and there is currently no therapeutic treatment for 
cryptosporidiosis (unlike giardiasis). Because Cryptosporidium is not 
generally inactivated in systems using standard disinfection practices, 
the control of Cryptosporidium is dependent on physical removal 
processes (e.g., filtration).
    The filter effluent turbidity limits specified under the SWTR were 
created to remove large parasite cysts such as Giardia and did not 
specifically control for smaller Cryptosporidium oocysts. In addition, 
filter backwash water recycling practices such as adding recycled water 
to the treatment train after primary coagulant addition may overwhelm 
the plant and harm efforts to control Giardia lamblia, Cryptosporidium, 
and emerging pathogens. Despite filtration and disinfection, 
Cryptosporidium oocysts have been found in filtered drinking water 
(LeChevallier, et al., 1991a; EPA, 1999c), and many of the individuals 
affected by waterborne disease outbreaks caused by Cryptosporidium were 
served by filtered surface water supplies (Solo-Gabriele and 
Neumeister, 1996). Surface water systems that filter and disinfect may 
still be vulnerable to Cryptosporidium, depending on the source water 
quality and treatment effectiveness. EPA believes that today's 
proposal, however, will ensure that drinking water treatment is 
operating efficiently to control Cryptosporidium (see Sections IV.A and 
IV.D) and other microbiological contaminants of concern (e.g., 
Giardia).
    In order to assess the public health risk associated with 
consumption of surface water or GWUDI from PWSs, EPA has evaluated 
information and conducted analysis in four important areas discussed in 
the following paragraphs. These areas are: (1) The health effects of 
cryptosporidiosis; (2) cryptosporidiosis waterborne disease outbreak 
data; (3) Cryptosporidium occurrence data from raw surface water, raw 
GWUDI, finished water, and recycle stream studies; and (4) an 
assessment of the current baseline surface water treatment required by 
existing regulations.

B. Health Effects of Cryptosporidiosis and Sources and Transmission of 
Cryptosporidium

    Waterborne diseases are usually acute (i.e., sudden onset and 
typically lasting a short time in healthy people), and most waterborne 
pathogens cause gastrointestinal illness, with diarrhea, abdominal 
discomfort, nausea, vomiting, and/or other symptoms. Some waterborne 
pathogens cause or are associated with more serious disorders such as 
hepatitis, gastric cancer, peptic ulcers, myocarditis, swollen lymph 
glands, meningitis, encephalitis, and many other diseases. 
Cryptosporidiosis is a protozoal infection that usually causes 7-14 
days of diarrhea with possibly a low-grade fever, nausea, and abdominal 
cramps in healthy individuals (Juranek, 1995). Unlike giardiasis for 
which effective antibiotic therapy is available, an antibiotic 
treatment for cryptosporidiosis does not exist (Framm and Soave, 1997).
    There are several species of Cryptosporidium which have been 
identified, including C. baileyi and C. meleagridis (bird host); C. 
muris (mouse host); C. nasorum (fish host), C. parvum (mammalian host), 
and C. serpentis (snake host). Cryptosporidium parvum was first 
recognized as a human pathogen in 1976 (Juranek, 1995). Recently, both 
the human and cattle types of C. parvum have been found in healthy 
individuals, and these types, C. felis, and a dog type have been found 
in immunocompromised individuals (Pieniazek et al., 1999). Transmission 
of cryptosporidiosis often occurs through the ingestion of infective 
Cryptosporidium oocysts from feces-contaminated food or water, but may 
also result from direct or indirect contact with infected persons or 
mammals (Casemore, 1990; Cordell and Addiss, 1994). Dupont, et. al., 
1995, found through a human feeding study that a low dose of C. parvum 
is

[[Page 19052]]

sufficient to cause infection in healthy adults (Dupont et. al., 1995). 
Animal agriculture as a nonpoint source of C. parvum has been 
implicated as the source of contamination for the 1993 outbreak in 
Milwaukee, Wisconsin, the largest outbreak of waterborne disease in the 
history of the United States (Walker et al., 1998). Other sources of C. 
parvum include discharges from municipal wastewater treatment 
facilities and drainage from slaughterhouses. In addition, rainfall 
appears to increase the concentration of Cryptosporidium in surface 
water, documented in a study by Atherholt, et al. (1998).
    There is evidence that an immune response to Cryptosporidium 
exists, but the degree and duration of this immunity is not well 
characterized (Fayer and Ungar, 1986). Recent work conducted by 
Chappell, et al. (1999) indicates that individuals with evidence of 
prior exposure to Cryptosporidium parvum have demonstrated immunity to 
low doses of oocysts (approximately 500 oocysts). The investigators 
found the 50 percent infectious dose for previously exposed individuals 
(possessing a pre-existing blood serum antibody) to be 1,880 oocysts 
compared to 132 oocysts for individuals without prior exposure, and 
individuals with prior exposure who became infected shed fewer oocysts. 
Because of this type of immune response, symptomatic infection in 
communities exposed to chronic low levels of oocysts will primarily be 
observed in newcomers (e.g., visitors, young children) (Frost et al., 
1997; Okhuysen et al., 1998).
    Sensitive populations are more likely to become infected and ill, 
and gastrointestinal illness among this population may be chronic. 
These sensitive populations include children, especially the very 
young; the elderly; pregnant women; and the immunocompromised (Gerba et 
al., 1996; Fayer and Ungar, 1986; EPA 1998e). This sensitive segment 
represents almost 20 percent of the population in the U.S. (Gerba et 
al., 1996). EPA is particularly concerned about the exposure of 
severely immunocompromised persons to Cryptosporidium in drinking 
water, because the severity and duration of illness is often greater in 
immunocompromised persons than in healthy individuals, and it may be 
fatal among this population. For instance, a follow-up study of the 
1993 Milwaukee, Wisconsin, waterborne disease outbreak reported that at 
least 50 Cryptosporidium-associated deaths occurred among the severely 
immunocompromised (Hoxie et al., 1997).
    Cases of illness from cryptosporidiosis were rarely reported until 
1982, when the disease became prevalent due to the AIDS epidemic 
(Current, 1983). As laboratory diagnostic techniques improved during 
subsequent years, outbreaks among immunocompetent persons were 
recognized as well. Over the last several years there have been a 
number of documented waterborne cryptosporidiosis outbreaks in the 
U.S., United Kingdom, Canada and other countries (Rose, 1997, Craun et 
al., 1998).

C. Waterborne Disease Outbreaks in the United States

    The occurrence of outbreaks of waterborne gastrointestinal 
infections, including cryptosporidiosis, may be much greater than 
suggested by reported surveillance data (Craun and Calderon 1996). The 
CDC-EPA, and the Council of State and Territorial Epidemiologists have 
maintained a collaborative surveillance program for collection and 
periodic reporting of data on waterborne disease outbreaks since 1971. 
The CDC database and biennial CDC-EPA surveillance summaries include 
data reported voluntarily by the States on the incidence and prevalence 
of waterborne illnesses. However, the following information 
demonstrates why the reported surveillance data may under-report actual 
outbreaks.
    The U.S. National Research Council strongly suggests that the 
number of identified and reported outbreaks in the CDC database (both 
for surface and ground waters) represents a small percentage of actual 
waterborne disease outbreaks National Research Council, 1997; Bennett 
et al., 1987). In practice, most waterborne outbreaks in community 
water systems are not recognized until a sizable proportion of the 
population is ill (Perz et al.)
    Healthy adults with cryptosporidiosis may not suffer severe 
symptoms from the disease; therefore, infected individuals may not seek 
medical assistance, and their cases are subsequently not reported. Even 
if infected individuals consult a physician, Cryptosporidium may not be 
identified by routine diagnostic tests for gastroenteritis and, 
therefore, tends to be under-reported in the general population 
(Juranek 1995). Such obstacles to outbreak reporting indicate that the 
incidence of disease and outbreaks of cryptosporidiosis may be much 
higher than officially reported by the CDC.
    The CDC database is based upon responses to a voluntary and 
confidential survey that is completed by State and local public health 
officials. CDC defines a waterborne disease outbreak as occurring when 
at least two persons experience a similar illness after ingesting water 
(Kramer et al., 1996). Cryptosporidiosis water system outbreak data 
from the CDC database appear in Table II.1 and Table II.2.
    Table II.1 illustrates the reported number of waterborne disease 
outbreaks in U.S. community, noncommunity, and individual drinking 
water systems between 1971 and 1996. According to the CDC-EPA database, 
a total of 652 outbreaks and 572,829 cases of illnesses were reported 
between 1971 and 1996 (see Table II-1). The total number of outbreaks 
reported includes outbreaks resulting from protozoan contamination, 
virus contamination, bacterial contamination, chemical contamination, 
and unknown factors.

 Table II.1.--Comparison of Outbreaks and Outbreak-Related Illnesses From Ground Water and Surface Water for the
                                              Period 1971-1996 \1\
----------------------------------------------------------------------------------------------------------------
                                                           Cases of \2\                           Outbreaks in
           Water source               Total outbreaks        illnesses      Outbreaks in CWSs        NCWSs
--------------------------------------------\2\-----------------------------------------------------------------
Ground............................  371 (57%).........  90,815 (16%)......                113                258
Surface...........................  223 (34%).........  471,375 (82%).....                148                 43
Other.............................  58 (9%)...........  10,639 (2%).......                 30                 19

[[Page 19053]]

 
All Systems \3\...................  652 (100%)........  572,829 (100%)....                291               320
----------------------------------------------------------------------------------------------------------------
\1\ Craun and Calderon, 1994, CDC, 1998.
\2\ Includes outbreaks in CWSs + NCWSs + Private wells.

    Epidemiological investigations of outbreaks in populations served 
by filtered systems have shown that treatment deficiencies have 
resulted in the plants' failure to remove contamination from the water. 
Sometimes operational deficiencies have been discovered only during 
post-outbreak investigations. Rose (1997) identified the following 
types of environmental and operating conditions commonly present in 
filtered surface water systems at the time cryptosporidiosis outbreaks 
have occurred:
     Improperly-installed, -operated, -maintained, or -
interpreted monitoring
     Equipment (e.g., turbidimeters);
     Inoperable flocculators, chemical injectors, or filters;
     Inadequate personnel response to failures of primary 
monitoring equipment;
     Filter backwash recycle;
     High concentrations of oocysts in source water with no 
mitigative barrier;
     Flushing of oocysts (by heavy rain or snow melt) from land 
surfaces upstream of the plant intakes; and
     Altered or suboptimal filtration during periods of high 
turbidity, with turbidity spikes detected in finished water.
    From 1984 to 1994, there have been 19 reported outbreaks of 
cryptosporidiosis in the U.S. (Craun et al., 1998). As mentioned 
previously, C. parvum was not identified as a human pathogen until 
1976. Furthermore, cryptosporidiosis outbreaks were not reported in the 
U.S. prior to 1984. Ten of these cryptosporidiosis outbreaks have been 
documented in CWSs, NCWSs, and a private water system (Moore et al., 
1993; Kramer et al., 1996; Levy et al., 1998; ; Craun et al., 1998). 
The remaining nine outbreaks were associated with recreational 
activities (Craun et al., 1998). The cryptosporidiosis outbreaks in 
U.S. drinking water systems are presented in Table II.2.

                                         Table II.2.--Cryptosporidiosis Outbreaks in U.S. Drinking Water Systems
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                        Location and CWS,       Cases of  illness
                Year                    NCWS, or private           (estimated)            Source water            Treatment           Suspected cause
--------------------------------------------------------------------------------------------------------------------------------------------------------
1984...............................  Braun Station, TX, CWS  117 (2,000)...........  Well.................  Chlorination.........  Sewage-contaminated
                                                                                                                                    well.
1987...............................  Carrollton, GA, CWS...  (13,000)..............  River................  Conventional           Treatment
                                                                                                             filtration/            deficiencies.
                                                                                                             chlorination;
                                                                                                             inadequate
                                                                                                             backwashing of some
                                                                                                             filters.
1991...............................  Berks County, PA, NCWS  (551).................  Well.................  Chlorination.........  Ground water under
                                                                                                                                    the influence of
                                                                                                                                    surface water.
1992...............................  Medford (Jackson        (3,000; combined total  Spring/River.........  Chlorination/package   Source not
                                      County), OR, CWS.       for Jackson County                             filtration plant.      identified.
                                                              and Talent, below).
1992...............................  Talent, OR, CWS.......  see Medford, OR.......  Spring/River.........  Chlorination/package   Treatment
                                                                                                             filtration plant.      deficiencies.
1993...............................  Milwaukee, WI, CWS....  (403,000).............  Lake.................  Conventional           High source water
                                                                                                             filtration.            contamination and
                                                                                                                                    treatment
                                                                                                                                    deficiencies.
1993...............................  Yakima, WA, private...  7.....................  Well.................  N/A..................  Ground water under
                                                                                                                                    the influence of
                                                                                                                                    surface water.
1993...............................  Cook County, MN, NCWS.  27....................  Lake.................  Filtered, chlorinated  Possible sewage
                                                                                                                                    backflow from toilet/
                                                                                                                                    septic tank.
1994...............................  Clark County, NV, CWS.  103; many confirmed     River/Lake...........  Prechlorination,       Source not
                                                              for cryptosporidiosis                          filtration and post-   identified.
                                                              were HIV positive.                             filtration
                                                                                                             chlorination.
1994...............................  Walla Walla, WA, CWS..  134...................  Well.................  None reported........  Sewage contamination.
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
Craun, et al., 1998.


[[Page 19054]]

    Six of the ten cryptosporidiosis outbreaks reported in Table II.2 
originated from surface water or possibly GWUDI supplied by public 
drinking water systems serving fewer than 10,000 persons. The first 
outbreak (117 known cases, 2,000 estimated cases of illness), in Braun 
Station, Texas in 1984, was caused by sewage leaking into a ground 
water well suspected to be under the influence of surface water. A 
second outbreak in Pennsylvania in 1991 (551 estimated cases of 
illness), occurred at a well also under the influence of surface water. 
The third and fourth (multi-episodic) outbreaks took place in Jackson 
County, Oregon in 1992 (3,000 estimated cases of illness) and were 
linked to treatment deficiencies in the Talent, OR surface water 
system. A fifth outbreak (27 cases of illness) in Minnesota, in 1993, 
occurred at a resort supplied by lake water. Finally, a sixth outbreak 
(134 cases of illness) in Washington in 1994, occurred due to sewage-
contaminated wells at a CWS.
    Three of the ten outbreaks (Carollton, GA (1987); Talent, OR 
(1992); Milwaukee, WI (1993)) were caused by water supplied by water 
treatment plants where the recycle of filter backwash was implicated as 
a possible cause of the outbreak. In total, the nine outbreaks which 
have taken place in PWSs have caused an estimated 419,939 cases of 
illness. These outbreaks illustrate that when treatment in place is not 
operating optimally or when source water is highly contaminated, 
Cryptosporidium may enter the finished drinking water and infect 
drinking water consumers, ultimately resulting in waterborne disease 
outbreaks.

D. Source Water Occurrence Studies

    Cryptosporidium is common in the environment (Rose, 1988; 
LeChevallier et al., 1991b). Runoff from unprotected watersheds allows 
the transport of these microorganisms from sources of oocysts (e.g., 
untreated wastewater, agricultural runoff) to water bodies used as 
intake sites for drinking water treatment plants. If treatment operates 
inefficiently, oocysts may enter the finished water at levels of public 
health concern. A particular public health challenge is that simply 
increasing existing disinfection levels above those most commonly 
practiced for standard disinfectants (i.e., chlorine or chloramines) in 
the U.S. today does not appear to be an effective strategy for 
controlling Cryptosporidium.
    Cryptosporidium oocysts have been detected in wastewater, pristine 
surface water, surface water receiving agricultural runoff or 
contaminated by sewage, ground water under the direct influence of 
surface water (GWUDI), water for recreational use, and drinking water 
(Rose 1997, Soave 1995). Over 25 environmental surveys have reported 
Cryptosporidium source water occurrence data from surface water or 
GWUDI (presented in Tables II.3 and II.4), which typically involved the 
collection of a few water samples from a number of sampling locations 
having different characteristics (e.g., polluted vs. pristine; lakes or 
reservoirs vs. rivers). Results are presented as oocysts per 100 
liters, unless otherwise marked.
    Each of the studies cited in Tables II.3 and II.4 presents 
Cryptosporidium source water occurrence information, including (where 
possible): (1) The number of samples collected; (2) the number of 
samples positive; and (3) both the means and ranges for the 
concentrations of Cryptosporidium detected (where available). However, 
the immunofluorescence assay (IFA) method and other Cryptosporidium 
detection methods are inaccurate and lack adequate precision. Current 
methods do not indicate the species of Cryptosporidium identified or 
whether the oocysts detected are viable or infectious (Frey et al., 
1997). The methods for detecting Cryptosporidium were modeled from 
Giardia methods, therefore recovery of Cryptosporidium is deficient 
primarily because Cryptosporidium oocysts are more difficult to capture 
due to their size (Cryptosporidium oocysts are 4-
6m; Giardia cysts are 8-
12m). In addition, it is a challenge to 
recover Cryptosporidium oocysts from the filters when they are 
concentrated, due to the adhesive character of the organisms. Other 
potential limitations to the protozoan detection methods include: (1) 
Filters used to concentrate the water samples are easily clogged by 
debris from the water sample; (2) interference occurs between debris or 
particulates that fluoresce due to cross reactivity of antibodies, 
which results in false positive identifications; (3) it is difficult to 
view the structure of oocysts on the membrane filter or slide, 
resulting in false negative determinations; and (4) most methods 
require an advanced level of skill to be performed accurately.
    Despite these limitations, the occurrence information generated 
from these studies demonstrates that Cryptosporidium occurs in source 
waters. The source waters for which EPA has compiled information 
include rivers, reservoirs, lakes, streams, raw water intakes, springs, 
wells under the influence of surface water and infiltration galleries. 
The most comprehensive study in scope and national representation 
(LeChevallier and Norton, 1995) will be described in further detail 
following Tables II.3 and II.4.

                              Table II.3.--Summary of Surface Water Survey and Monitoring Data for Cryptosporidium Oocysts
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                        Samples
                                        Number of    positive  for      Range of oocyst  conc.
            Sample source              samples (n)  Cryptosporidium         (oocysts/100L)             Mean  (oocysts/100L)             Reference
                                                       (percent)a
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rivers...............................           25            100    200-11,200..................  2510........................  Ongerth and Stibbs
                                                                                                                                  1987.
River................................            6            100    200-580,000.................  192,000(a)..................  Madore et al. 1987.
Reservoirs/rivers (polluted).........            6            100    19-300......................  99(a).......................  Rose 1988.
Reservoir (pristine).................            6             83    1-13........................  2(a)........................  Rose 1988.
Impacted river.......................           11            100    200-11,200b.................  2,500(g)....................  Rose et al. 1988ab.
Lake.................................           20             71    0-2200......................  58(g).......................  Rose et al. 1988bb.
Stream...............................           19             74    0-24,000....................  109(g)......................  Rose et al. 1988bb
Raw water............................           85             87    7-48,400....................  270(g) detectable...........  LeChevallier et al.
                                                                                                                                  1991c.
River (pristine).....................           59             32    NR..........................  29(g).......................  Rose et al. 1991.
River (polluted).....................           38             74    0.1-4,400b..................  66(g).......................  Rose et al. 1991.
Lake/reservoir (pristine)............           34             53    NR..........................  9.3(g)......................  Rose et al. 1991.
Lake/reservoir (polluted)............           24             58    0.1-380b....................  103(g)......................  Rose et al. 1991.

[[Page 19055]]

 
River (all samples)..................           36             97    15-45 (pristine) 1000-6,350   20 (pristine) 1,830           Hansen and Ongerth
                                                                      (agricultural).               (agricultural).               1991.
Protected drinking water supply                  6             81    15-42.......................  24(g).......................  Hansen and Ongerth
 (subset of all).                                                                                                                 1991.
Pristine river, forestry area (subset            6            100    46-697......................  162(g)......................  Hansen and Ongerth
 of all).                                                                                                                         1991.
River below rural community in                   6            100    54-360......................  107(g)......................  Hansen and Ongerth
 forested area (subset of all).                                                                                                   1991.
River below dairy farming                        6            100    330-6,350...................  1,072(g)....................  Hansen and Ongerth
 agricultural activities (subset of                                                                                               1991.
 all).
Reservoirs...........................           56             45    NR..........................  NR..........................  Consonery et al. 1992.
Streams..............................           33             48    NR..........................  NR..........................  Consonery et al. 1992.
Rivers...............................           37             51    NR..........................  NR..........................  Consonery et al. 1992.
Site 1--River source (high turbidity)           10            100    82-7,190....................  480.........................  LeChevallier and Norton
                                                                                                                                  1992.
Site 2--River source (moderate                  10             70    42-510......................  250.........................  LeChevallier and Norton
 turbidity).                                                                                                                      1992.
Site 3--Reservoir source (low                   10             70    77-870......................  250.........................  LeChevallier and Norton
 turbidity).                                                                                                                      1992.
Lakes................................          179              6    0-2,240.....................  3.3 (median)................  Archer et al. 1995.
Streams..............................          210              6    0-2,000.....................  7 (median)..................  Archer et al. 1995.
Finished water.......................          262             13    0.29-57.....................  33 (detectable).............  LeChevallier and Norton
                                                                                                                                  1995.
River/lake...........................          262             52    6.5-6,510...................  240 (detectable)............  LeChevallier and Norton
                                                                                                                                  1995.
River/lake...........................          147             20    30-980......................  200.........................  LeChevallier et al.
                                                                                                                                  1995.
River 1..............................           15             73    0-2,230.....................  188 (a) all samples 43 (g)    States et al. 1995.
                                                                                                    detected.
River 2..............................           15             80    0-1,470.....................  147 (a) all samples 61 (g)    States et al. 1995.
                                                                                                    detected.
Dairy farm stream....................           13             77    0-1,110.....................  126 (a) all samples 55 (g)    States et al. 1995.
                                                                                                    detected.
Reservoir inlets.....................           60              5    0.7-24......................  1.9(g) 1.6 (median).........  LeChevallier et al.
                                                                                                                                  1997b.
Reservoir outlets....................           60             12    1.2-107.....................  6.1(g) 60 (median)..........  LeChevallier et al.
                                                                                                                                  1997b.
River (polluted).....................           72             40    20-280......................  24(g).......................  LeChevallier et al.
                                                                                                                                  1997a.
Source water.........................           NR             24    1-5,390c....................  740(a)c 71(g)c..............  Swertfeger et al. 1997.
First flush (storm event)............           20             35    0-41,700....................  NR..........................  Stewart et al. 1997.
Grab (non-storm event)...............           21             19    0-650.......................  NR..........................  Stewart et al. 1997.
River 1..............................           24             63    0-1,470.....................  58(g).......................  States et al. 1997.
Stream by dairy farm.................           22             82    0-2,300.....................  42(g).......................  States et al. 1997.
River 2 (at plant intake)............           24             63    0-2,200.....................  31(g).......................  States et al. 1997.
Reservoirs (unfiltered system).......           NR         37-52d    15-43 (maxima)d.............  0.8-1.4d....................  Okun et al. 1997.
Raw water intakes....................          148             25    0.04-18.....................  0.3.........................  Consonery et al. 1997.
Raw water intakes (rural)............           NR             NR    40-400......................  NR..........................  Swiger et al. 1999.
Raw Water............................   100 plants             77    0.5-117.....................  3(g)........................  McTigue, et al. 1998.
DE River, Winter.....................           18             NR    NR..........................  70 per 500L(g)..............  Atherholt, et al. 1998.
DE River, Spring.....................           18             NR    NR..........................  100 per 500L(g).............  Atherholt, et al. 1998.
DE River, Summer.....................           18             NR    NR..........................  30 per 500L(g)..............  Atherholt, et al. 1998.
DE River, Fall.......................           18             NR    NR..........................  20 per 500L(g)..............  Atherholt, et al. 1998.
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
a Rounded to nearest percent.
b As cited in Lisle and Rose 1995.
c Based on presumptive oocyst count
d Combined monitoring results for multiple sites in large urban water supply.
e As cited in States et al. 1997.
(a) = arithmetic average.
(g) = geometric average.
NR = not reported, NA = not applicable.


[[Page 19056]]


                                     Table II.4.--Summary of U.S. GWUDI Monitoring Data for Cryptosporidium Oocysts
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Samples positive for
           Sample source             Number of samples (n)      Cryptosporidium        Range of positive    Mean (oocysts/ 100L) a        Reference
                                                               oocysts (percent)     values (oocysts/100L)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Well..............................  17 (6 wells)..........  (1 sample)............  .085L                   NA                      Archer et al. 1995.
Ground water sources (all           199 sites\b\..........  11\b\.................  0.002-0.45d             NR                      Hancock et al. 1998.
 categories).
Vertical wells (subcategory of      149 sites\b\..........  5\b\..................  NR                      NR                      Hancock et al. 1998.
 above ground water sources).
Springs (subcategory of above       35 sites\b\...........  20\b\.................  NR                      NR                      Hancock et al. 1998.
 ground water sources).
Infiltration galleries              4 sites\b\............  50\b\.................  NR                      NR                      Hancock et al. 1998.
 (subcategory of above ground
 water sources).
Horizontal wells (subcategory of    11 sites\b\...........   45\b\................  NR                      NR                      Hancock et al. 1998.
 above ground water sources).
Ground water......................  17....................  41.2..................  NR                      NR                      Rosen et al., 1996.
Ground water......................  18....................  5.6...................  .13                     .13                     Rose et al. 1991.
Springs...........................  7 (4 springs).........   57\b\................  0.25-10                 4                       Rose et al. 1991.
Wells.............................  5 sites...............  100...................  0.26-3                  0.9                     SAIC, 1997 c
Vertical well Lemont Well #4        6.....................  66.7..................  NR                      NR                      Lee, 1993.
 (Center Co., PA, Aug. 1992).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Geometric mean reported unless otherwise indicated.
\b\ Data are presented as the percentage of positive sites.
\c\ Data included are confirmed positive samples not reported in Hancock, 1998.
NA = not applicable.
NR = not reported.

    The LeChevallier and Norton (1995) study collected the most samples 
and repeat samples from the largest number of surface water plants 
nationally. LeChevallier and Norton conducted the study to determine 
the level of Cryptosporidium in surface water supplies and plant 
effluent water. In total, surface water sources for 72 treatment plants 
in 15 States and 2 Canadian provinces were sampled. Sixty-seven surface 
water locations were examined. The generated data set covered a two-
year monitoring period (March, 1991 to January, 1993) which was 
combined with a previous set of data (October, 1988 to June, 1990) 
collected from most of the same set of systems to create a database 
containing five samples (IFA) per site or more for 94 percent of the 67 
systems sampled. Cryptosporidium oocysts were detected in 135 (51.5 
percent) of the 262 raw water samples collected between March 1991 and 
January 1993, while 87 percent of the 85 samples were positive during 
the survey period from October, 1988 to June, 1990. The geometric mean 
of detectable Cryptosporidium was 240 oocysts/100L, with a range from 
6.5 to 6510 oocysts/100L. When the 1991-1993 results (n=262) were 
combined with the previous results (n=85), Cryptosporidium was detected 
in 60.2 percent of the samples. The authors hypothesize the origin of 
the decrease in detections in the second round of sampling to be most 
probably linked to fluctuating or declining source water concentrations 
of Cryptosporidium oocysts from the first reporting period to the 
second.
    LeChevallier and Norton (1995) also detected Cryptosporidium 
oocysts in 35 of 262 plant effluent samples (13.4 percent) analyzed 
between 1991 and 1993. When detected, the oocyst levels averaged 3.3 
oocysts/100 L (range = 0.29 to 57 oocysts/100 L). A summary of 
occurrence data for all samples in filtered effluents for the years 
1988 to 1993 showed that 32 of the water treatment plants (45 percent) 
were consistently negative for Cryptosporidium; 24 plants (34 percent) 
were positive once; and 15 plants (21 percent) were positive for 
Cryptosporidium two or more times between 1988 to 1993. Forty-four of 
the plants (62 percent) were positive for Giardia, Cryptosporidium, or 
both at one time or another (LeChevallier and Norton 1995).
    The oocyst recoveries and densities reported by LeChevallier and 
Norton (1995) are comparable to the results of another survey of 
treated, untreated, protected (pristine) and feces-contaminated 
(polluted) water supplies (Rose et al. 1991). Six of thirty-six samples 
(17 percent) taken from potable drinking water were positive for 
Cryptosporidium, and concentrations in these waters ranged from .5 to 
1.7 oocysts/100L. In addition, a total of 188 surface water samples 
were analyzed from rivers, lakes, or springs in 17 States. The majority 
of surface water samples were obtained from Arizona, California, and 
Utah (126 samples in all), with others from eastern States (28 
samples), northwestern States (14 samples), southern States (13 
samples), midwestern States (6 samples), and Hawaii (1 sample). 
Arithmetic average oocyst concentrations ranged from less than 1 to 
4,400 oocysts/100 L, depending on the type of water analyzed. 
Cryptosporidium oocysts were found in 55 percent of the surface water 
samples at an average concentration of 43 oocysts/100 L.
    The LeChevallier and Norton (1995) study collected the most samples 
and repeat samples from the most surface water plants on a national 
level. Therefore, the data from this study were analyzed by EPA (EPA, 
1998n) to generate a distribution of source water occurrence, presented 
in Table II.5.

  Table II.5.--Baseline Expected National Source Water Cryptosporidium
                              Distributions
------------------------------------------------------------------------
                                                          Source  water
                      Percentile                          concentration
                                                         (oocysts/100L)
------------------------------------------------------------------------
25....................................................               103
50....................................................               231
75....................................................               516
90....................................................              1064
95....................................................              1641
    Mean..............................................               470
    Standard Deviation................................               841
------------------------------------------------------------------------

    Although limited by the small number of samples per site (one to 
sixteen samples; most sites were sampled five times), the mean 
concentration at the 69

[[Page 19057]]

sites from the eastern and central U.S. seems to be represented by a 
lognormal distribution.
    In addition to the source water data, several studies have detected 
Cryptosporidium oocysts in finished water. The results of these studies 
have been compiled in Table II.6.

                                 Table II.6.--Summary of U.S. Finished Water Monitoring Data for Cryptosporidium Oocysts
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                            Samples
                                           Number of      positive for      Range of oocyst conc.
             Sample source                samples (n)   Cryptosporidium        (oocysts/100L)           Mean (oocysts/100L)             Reference
                                                           (percent)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Filtered water........................              82               27  0.1-48....................  1.5......................  LeChevallier et al.
                                                                                                                                 1991a.
Finished water (unfiltered)...........               6               33  0.1-1.7...................  0.2......................  LeChevallier et al.
                                                                                                                                 1992.
Finished water........................             262               13  0.29-57...................  33 (detectable)..........  LeChevallier and Norton
                                                                                                                                 1995.
Finished water (clearwell)............              14               14  NR........................  NR.......................  Consonery et al. 1992.
Finished water (filter effluents).....             118               26  NR........................  NR.......................  Consonery et al. 1992.
Site 1--Filter effluent...............              10               70  1-4.......................  NR.......................  LeChevallier and Norton
                                                                                                                                 1992.
Site 2--Filter effluent...............              10               10  0.5.......................  NA.......................  LeChevallier and Norton
                                                                                                                                 1992.
Site 3--Filter effluent...............              10               10  2.........................  NA.......................  LeChevallier and Norton
                                                                                                                                 1992.
Finished water........................           1,237                7  NR........................  NR.......................  Rosen et al. 1996.
Filtered (non-storm event)............              87               10  0-420.....................  NR.......................  Stewart et al. 1997a.
Finished water........................              24              **8  0-0.6.....................  0.5 (g)..................  States et al. 1997.
                                                                  ***13
Finished water........................             155              2.5  0.02-0.8..................  0.2......................  Consonery et al. 1997.
Finished water........................             100               15  0.04-0.08.................  0.08 (g).................  McTigue, et al. 1998.
--------------------------------------------------------------------------------------------------------------------------------------------------------
*Plants
**Confirmed
***Presumed

    These studies show that despite some treatment in place, 
Cryptosporidium may still pass through the treatment plant and into 
finished water.
    In general, oocysts are detected more frequently and in higher 
concentrations in rivers and streams than in lakes and reservoirs 
(LeChevallier et al., 1991b; Rose et al., 1988a,b). Madore et al. 
(1987) found high concentrations of oocysts in a river affected by 
agricultural runoff (5800 oocysts/L). Such concentrations are 
especially significant if the contaminant removal process (e.g., 
sedimentation, filtration) of the treatment plant is not operating 
effectively. Oocysts may pass through to the finished water, as 
LeChevallier and Norton (1995) and several other researchers also 
found, and infect drinking water consumers.

E. Filter Backwash and Other Process Streams: Occurrence and Impact 
Studies

    Pathogenic microorganisms are removed during the sedimentation and/
or filtration processes in a water treatment plant. Recycle streams 
generated during treatment, such as spent filter backwash water, 
sedimentation basin sludge, or thickener supernatant are often returned 
to the treatment train. These recycle streams, therefore, may contain 
high concentrations of pathogens, including chlorine-resistant 
Cryptosporidium oocysts. Recycle can degrade the treatment process, 
especially when entering the treatment train after the rapid mix stage, 
by causing a chemical imbalance, hydraulic surge and potentially 
overwhelming the plant's filtration capacity with a large concentration 
of pathogens. High oocyst concentrations found in recycle waters can 
increase the risk of pathogens passing through the treatment plant into 
finished water.
    AWWA has compiled issue papers on each of the following recycle 
streams: Spent filter backwash water, sedimentation basin solids, 
combined thickener supernatant, ion-exchange regenerate, membrane 
concentrate, lagoon decant, mechanical dewatering device concentrate, 
monofill leachate, sludge drying bed leachate, and small-volume streams 
(e.g., floor, roof, lab drains) (Environmental Engineering & 
Technology, 1999). In addition, EPA compiled existing occurrence data 
on Cryptosporidium in recycle streams. Through these efforts, 
Cryptosporidium occurrence data has been found for three types of 
recycle streams: Spent filter backwash water, sedimentation basin 
solids, and thickener supernatant.
    Nine studies have reported the occurrence of Cryptosporidium for 
these process streams. Each study's scope and results are presented in 
Table II.7, and brief narratives on each major study follow the table. 
Note that the results of the studies, if not presented in the published 
report as oocysts/100L, have been converted into oocysts/100L.

                                  Table II.7.--Cryptosporidium Occurrence in Filter Backwash and Other Recycle Streams
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                               Number of treatment
      Name/location of study        Number of samples (n)      Type of sample      Cyst/oocyst concentration     plants sampled           Reference
--------------------------------------------------------------------------------------------------------------------------------------------------------
Drinking water treatment            2....................  backflush waters from  sample 1: 26,000 oocysts/   2...................  Rose et al. 1986.
 facilities.                                                rapid sand filters.    gal (calc. as 686,900
                                                                                   oocysts/100L).
                                                                                  sample 2: 92,000 oocysts/
                                                                                   gal (calc as 2,430,600
                                                                                   oocysts/100L)

[[Page 19058]]

 
Thames, U.K.,.....................  not reported.........  backwash water from    Over 1,000,000 oocysts/     1...................  Colbourne 1989.
                                                            rapid sand filter.     100L in backwash water on
                                                                                   2/19/89.
                                                                                  100,000 oocysts/100L in
                                                                                   supernatant from
                                                                                   settlement tanks during
                                                                                   the next few days
Potable water supplies in 17        not reported.........  filter backwash from   217 oocysts/ 100 L          not reported........  Rose et al. 1991.
 States.                                                    rapid sand filters     (geometric mean).
                                                            (10 to 40 L sample
                                                            vol.).
Name/location not reported........  not reported.........  raw water............  7 to 108 oocysts/100L.....  not reported........  LeChevallier et al.
                                                           initial backwash       detected at levels 57 to    not reported........   1991c.
                                                            water.                 61 times higher than in
                                                                                   the raw water.
Bangor Water Treatment Plant (PA).  Round 1: 1 (8-hour     raw water............  902 oocysts/100L.           141 oocysts/100L. 1   Cornwell and Lee
                                     composite).           filter backwash......                                                     1993.
                                                           supernatant recycle 6
                                                            oocysts/100L.
Round 2: 1 (8-hour composite).....  raw water............  140 oocysts/100L.....  850 oocysts/100L.           750 oocysts/100L. 1   Cornwell and Lee
                                    filter backwash......                                                                            1993.
                                    supernatant recycle..
Moshannon Valley Water Treatment    Round 1: 1 (8-hour     raw water............  16,613 oocysts/100L.        82 oocysts/100L.      2,642 oocysts/100L.
 Plant.                              composite).           spent backwash.......                                                     1 Cornwell and Lee
                                                           supernatant recycle..                                                     1993.
                                                           sludge 13 oocysts/
                                                            100L.
                                    Round 2: 1 (8-hour     raw water............  20 oocysts/100L...........  420 oocysts/100L. 1   Cornwell and Lee
                                     composite).           supernatant recycle..                                                     1993.
Plant ``C''.......................  11 samples using       39 samples using       backwash water from rapid   continuous flow:      cartridge filters:
                                     continuous flow        cartridge filters.     sand filters; samples       range 1 to 69         ranges 0.8 to 252/
                                     centrifugation;.                              collected from              oocysts/100 L; 8 of   100 L; 33 of 39
                                                                                   sedimentation basins        11 samples positive.  samples positive 1
                                                                                   during sedimentation                              Karanis et al.
                                                                                   phase of backwash water                           1996.
                                                                                   at depths of 1, 2, 3, and
                                                                                   3.3 m.
Pittsburgh Drinking Water           24 (two years of       filter backwash......  328 oocysts/ 100 L          non-detect-13,158     States et al. 1997.
 Treatment Plant.                    monthly samples).                             (geometric mean); (38       oocysts/100L. 1
                                                                                   percent occurrence rate).
``Plant Number 3''................  not reported.........  raw water............  140 oocysts/100L..........  850 oocysts/100L.     not reported
                                                           spent backwash.......                                                     Cornwell 1997.
``Plant C'' (see Karanis, et al.,   12...................  raw water............  avg. 23.2 oocysts/100L      avg. 22.1 oocysts/    1 Karanis et al
 1996).                             50...................  backwash water from     (max. 109 oocysts/100L)     100L (max. 257        1998.
                                                            rapid sand filters.    in 8 of 12 samples.         oocysts/100L) in 41
                                                                                                               of 50 samples
``Plant A''.......................  1....................  rapid sand filter      150 oocysts/100L..........
                                                            (sample taken 10
                                                            min. after start of
                                                            backwashing).
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The occurrence data available and reported are primarily for raw 
and recycle stream water. If filter backwash enters the treatment train 
as a slug load and disrupts the treatment process, it is possible its 
effects would not be readily seen in the finished water until several 
minutes or hours after returning the filter to service. In addition, 
the poor recovery efficiencies of the IFA Cryptosporidium detection 
method complicate measurements in dilute finished effluent waters.
    As shown in Table II.7, the concentrations of oocysts in backwash 
water and other recycle streams are greater than the concentrations 
generally found in raw water. For example, four studies (Cornwell and 
Lee, 1993; States et al., 1997; Rose et al., 1986; and Colbourne, 1989) 
have reported Cryptosporidium oocyst concentrations in filter backwash 
water exceeding 10,000 oocysts/100L. Such concentrations illustrate 
that the treatment plant has been removing oocysts from the influent 
water during the sedimentation and/or filtration processes. As 
expected, the oocysts have concentrated on the filters and/or in the 
sedimentation basin sludge. Therefore, the recycling of such process 
streams (e.g., filter backwash, thickener supernatant, sedimentation 
basin

[[Page 19059]]

sludge) re-introduces high concentrations of oocysts to the drinking 
water treatment train.
    Recycle can potentially return a significant number of oocysts to 
the treatment plant in a short amount of time, particularly if the 
recycle is returned to the treatment process without prior treatment, 
equalization, or some other type of hydraulic detention. In addition, 
Di Giovanni, et al. (1999) presented data indicating that viable 
oocysts have been detected in filter backwash samples using a cell 
culture/polymerase chain reaction (PCR) method. Cell culture is a test 
of the viability/infectivity of the oocysts, while PCR identified the 
cells infected by C. parvum. Although recovery by IFA was poor (6 to 8 
percent for backwash samples), 9 filter backwash recycle samples were 
found to contain viable and infectious oocysts, and the infectious 
agent was determined to be more than 98 percent similar in structure to 
C. parvum. Should filter backwash recycle disrupt normal treatment 
operations or should treatment not function efficiently due to other 
deficiencies, high concentrations of potentially viable, infectious 
oocysts may pass through the plant into finished drinking water. The 
recycle stream occurrence studies presented in Table II.7 are described 
in further detail in the following sections.

Thames, U.K. Water Utilities Experience with Cryptosporidium, Colbourne 
(1989)

    In response to a cryptosporidiosis outbreak reported in February of 
1989, Thames Water undertook an investigation of pathogen 
concentrations within the Farmoor conventional treatment plant's 
treatment train, finished and raw waters. The investigation occurred 
over a two month period, from February to April 1989 and included 
sampling of settled filter backwash, the supernatant from spent filter 
backwash, raw water, and water sampled at the end of various Thames 
distribution points.
    On February 19, 1989 at the start of the outbreak investigation, a 
concentration of approximately 1,000,000 oocysts/100L was detected in 
the filter backwash water. During the first few days of the following 
investigation, the supernatant of the settled backwash water contained 
approximately 100,000 oocysts/100L. At the peak of the outbreak, thirty 
percent of Thames' distribution system samples were positive for 
oocysts, and ranged in concentration from 0.2 to 7700 oocysts/100L. Raw 
reservoir water contained oocyst concentrations ranging from .2 to 1400 
oocysts/100L. After washing the filters twice in 24 hours, no oocysts 
were found in the settled backwash waters. Thames, U.K. Water Utilities 
determined that a storm causing intense precipitation and runoff 
resulted in elevated levels of oocysts in the source water which led to 
the high concentrations of oocysts entering the plant and subsequently 
deposited on the filters and recycled as filter backwash.

Survey of Potable Water Supplies for Cryptosporidium and Giardia, Rose, 
et al., 1991

    In this survey, Rose, et al., collected 257 samples from 17 States 
from 1985 to 1988. The samples were collected on cartridge filters and 
analyzed using variations of the IFA method. The reported percent 
recovery for the method was 29 to 58 percent. Filter backwash samples 
were a subset of the 257, 10 to 40 L samples were collected from rapid 
sand filters.
    Rose, et al. reported the geometric mean of the backwash samples at 
217 Cryptosporidium oocysts/100L. This was the highest reported average 
Cryptosporidium concentration of any of the water types tested, which 
included polluted and pristine surface and ground water sources, 
drinking water sources in addition to filter backwash recycle water.

Giardia and Cryptosporidium in Water Supplies, LeChevallier, et al. 
(1991c)

    LeChevallier et al. conducted a study to determine ``whether 
compliance with the SWTR would ensure control of Giardia in potable 
water supplies.'' Raw water and plant effluent samples were collected 
from 66 surface water treatment plants in 14 States and one Canadian 
province, although only selected sites were tested for Cryptosporidium 
oocysts in filter backwash and settled backwash water.
    In the analysis of pathogen concentrations in the raw water and 
filter backwash water of the water treatment process, LeChevallier et 
al. (1991c) found very high oocyst levels in backwash water of 
utilities that had low raw water parasite concentrations. The pathogens 
were detected using a combined IFA method that the authors developed. 
Cryptosporidium levels in the initial backwash water were 57 to 61 
times higher than in the raw water supplies. Raw water samples were 
found to contain from 7 to 108 oocysts/100L. LeChevallier et al. 
(1991c) also noted that when Cryptosporidium were detected in plant 
effluent samples (12 of 13 times), the organisms were also observed in 
the backwash samples. The study concluded that the consistency of these 
results shows that accumulation of parasites in the treatment filters 
(and subsequent release in the filter backwash recycle water) could be 
related to subsequent passage through treatment barriers.

Recycle Stream Effects on Water Treatment, Cornwell and Lee (1993, 
1994)

    The results described in Cornwell and Lee's 1993 American Water 
Works Association Research Foundation Report and 1994 Journal of the 
American Water Works Association article on the Bangor and Moshannon 
Valley, PA water treatment plants are consistent with the results of 
States et al. (1997). In total, Cornwell and Lee investigated eight 
water treatment plants, examining treatment efficiencies including 
several recycle streams and their impacts, and reporting a range of 
pathogen and other water quality data. All of the pathogen testing was 
conducted using the EPA IFA method refined by LeChevallier, et al. 
(1991c).
    Cornwell and Lee (1993) conducted two rounds of sampling at both 
the Bangor and Moshannon plants, sampling the different recycle and 
treatment streams as eight-hour composites. They detected 
Cryptosporidium concentrations of over 16,500 Cryptosporidium oocysts/
100L in the backwash water at an adsorption clarifier plant (Moshannon 
Valley) and over 850 Cryptosporidium oocysts/100L in backwash water 
from a direct filtration plant (Bangor). The parasite levels in the 
backwash samples were significantly higher than concentrations found in 
the raw source water, which contained Cryptosporidium oocyst 
concentrations of 13-20 oocysts/100L at the Moshannon Valley plant and 
6-140 oocysts/100L at the Bangor plant.
    In addition, Cornwell and Lee determined oocyst concentrations for 
two other recycle streams, combined thickener supernatant and 
sedimentation basin solids. The supernatant pathogen concentrations 
were reported at 141 Cryptosporidium oocysts/100L at the Bangor plant, 
and levels were reported at 82 to 420 oocysts/100L for the Moshannon 
plant in Rounds 1 and 2 of sampling, respectively. The sedimentation 
basin sludge was reported at 2,642 Cryptosporidium oocysts/100L in the 
clarifier sludge from the Moshannon Valley plant.

[[Page 19060]]

Giardia and Cryptosporidium in Backwash Water from Rapid Sand Filters 
Used for Drinking Water, Karanis et al. (1996) and Distribution and 
Removal of Giardia and Cryptosporidium in Water Supplies in Germany 
Karanis, et al. (1998)

    Karanis et al. (1996 and 1998) conducted a four-year research study 
(samples collected from July, 1993-December, 1995) on the efficiency of 
Cryptosporidium removal by six different surface water treatment plants 
from Germany, all of which treat by conventional filtration. The method 
used was an IFA method dubbed the ``EPA method'', developed by 
Jakubowski and Ericksen, 1979.
    Karanis et al. (1996) detected Cryptosporidium in 82 percent of the 
samples of backwash water from rapid sand filters of a water treatment 
plant (``Plant C'') supplied by small rivers. Eight out of 12 raw water 
samples tested were positive for Cryptosporidium (range of 0.8 to 109 
oocysts/100L). Backwash water samples collected by continuous flow 
centrifugation were positive for Cryptosporidium in 8 of 11 samples 
(range of 1 to 69/100L). Of 39 samples collected using cartridge 
filters, 33 were positive for Cryptosporidium (range of 0.8 to 252/
100L). The authors called attention to the high detection rate of 
Cryptosporidium in the backwash waters (82 percent) of Plant C and to 
the fact that the supernatant following sedimentation was not free from 
cysts and oocysts (Karanis et al. 1996).
    In the 1998 publication, Karanis et al. compiled the data from the 
1996 study with more backwash occurrence data collected from another 
treatment plant (``Plant A''). The filter backwash of Plant A was 
sampled 10 minutes after the start of backwashing, and the backwash 
water was found to contain 150 Cryptosporidium oocysts/100L.

Protozoa in River Water: Sources, Occurrence, and Treatment, States, et 
al. (1997)

    Over a two year period (July, 1994-June, 1996), States et al. 
sampled monthly for Cryptosporidium in the raw, settled, filtered and 
filter backwash water at the Pittsburgh Drinking Water Treatment Plant, 
in order to gauge the efficiency of pathogen removal at the plant. 
States et al. identified several sources contributing oocysts to the 
influent water, including sewage plant effluent, combined sewer 
overflows, dairy farm streams, and recycling of backwash water. All 
pathogen sampling was conducted with the IFA method.
    Cryptosporidium occurred in the raw Allegheny river water supplying 
the plant with a geometric mean of 31 oocysts/100L in 63 percent of 
samples collected, and ranged from non-detect to 2,333 oocysts/100L 
(see Table II.3 for source water information). Of the filter backwash 
samples, a geometric mean of 328 oocysts/100L was found at an 
occurrence rate of 38 percent of samples, with a range from non-detect 
to 13,158 oocysts/100L. The fact that the mean concentration of 
Cryptosporidium oocysts in backwash water can be substantially higher 
than the oocyst concentration in untreated river water suggests that 
recycling untreated filter backwash water can be a significant source 
of this parasite to water within the treatment process.

F. Summary and Conclusions

    Cryptosporidiosis is a disease without a therapeutic cure, and its 
causative agent, Cryptosporidium, is resistant to chlorine 
disinfection. Cryptosporidium has been known to cause severe illness, 
especially in immunocompromised individuals, and can be fatal. Several 
waterborne cryptosporidiosis outbreaks have been reported, and it is 
likely that others have occurred but have gone unreported. 
Cryptosporidium has been detected in a wide range of source waters, 
documented in over 30 studies from the literature, and it has been 
found at levels of concern in filter backwash water and other recycle 
streams.
    One of the key regulations EPA has developed and implemented to 
counter pathogens in drinking water is the SWTR (54 FR 27486, June 19, 
1989). The SWTR requires that surface water systems have sufficient 
treatment to reduce the source water concentration of Giardia and 
viruses by at least 99.9 percent (3 log) and 99.99 percent (4 log), 
respectively. A shortcoming of the SWTR, however, is that the rule does 
not specifically control for Cryptosporidium. The first report of a 
recognized waterborne outbreak caused by Cryptosporidium was published 
during the development of the SWTR (D'Antonio et al. 1985).
    In 1998, the Agency finalized the IESWTR that enhances the 
microbial pathogen protection provided by the SWTR for systems serving 
10,000 or more persons. The IESWTR includes an MCLG of zero for 
Cryptosporidium and requires a minimum 2-log (99 percent) removal of 
Cryptosporidium, linked to enhanced combined filter effluent and 
individual filter turbidity control provisions.
    Several provisions of today's proposed rule, the LT1FBR, are 
designed to address the concerns covered by the IESWTR, improving 
control of Cryptosporidium and other microbial contaminants, for the 
portion of the public served by small PWSs (i.e., serving less than 
10,000 persons). The LT1FBR also addresses the concern that for all 
PWSs that practice recycling, Cryptosporidium (and other emerging 
pathogens resistant to standard disinfection practice) are reintroduced 
to the treatment process of PWSs by the recycle of spent filter 
backwash water, solids treatment residuals, and other process streams.
    Insufficient treatment practices have been cited as the cause of 
several reported waterborne disease outbreaks (Rose, 1997). Rose (1997) 
also found that a reduction in turbidity is indicative of a more 
efficient filtration process. Therefore, the turbidity and filter 
monitoring requirements of today's proposed LT1FBR will ensure that the 
removal process necessary to protect the public from cryptosporidiosis 
is operating properly, and the recycle stream provisions will ensure 
that the treatment process is not disrupted or operating inefficiently. 
The LT1FBR requirements that address the potential for Cryptosporidium 
to enter the finished drinking water supply will be described in more 
detail in the following sections.

III. Baseline Information-Systems Potentially Affected By Today's 
Proposed Rule

    EPA utilized the 1997 state-verified version of the Safe Drinking 
Water Information System (SDWIS) to develop the total universe of 
systems which utilize surface water or groundwater under the direct 
influence (GWUDI) as sources. This universe consists of 11,593 systems 
serving fewer than 10,000 persons, and 2,096 systems serving 10,000 or 
more persons. Given this initial baseline, the Agency developed 
estimates of the number of systems which would be affected by 
components of today's proposed rule by utilizing three primary sources: 
Safe Drinking Water Information Systems; Community Water Supply Survey; 
and Water: Stats. A brief overview of each of the data sources is 
described in the following paragraphs.

Safe Drinking Water Information System (SDWIS)

    SDWIS contains information about PWSs including violations of EPA's 
regulations for safe drinking water. Pertinent information in this 
database includes system name and ID, population served, geographic 
location,

[[Page 19061]]

type of source water, and type of treatment (if provided).

Community Water System Survey (CWSS)

    EPA conducted the 1995 CWSS to obtain data to support its 
development and evaluation of drinking water regulations. The survey 
consisted of a stratified random sample of 3,700 water systems 
nationwide (surface water and groundwater). The survey asked 24 
operational and 13 financial questions.

Water:/Stats (WaterStats)

    WaterStats is an in-depth database of water utility information 
compiled by the American Water Works Association. The database consists 
of 898 utilities of all sizes and provides a variety of data including 
treatment information.
    Information regarding estimates of the number of systems which may 
potentially be affected by specific components of today's proposed rule 
can be found in the discussion of each proposed rule component in 
Section IV.

IV. Discussion of Proposed LT1FBR Requirements

A. Enhanced Filtration Requirements

    As discussed earlier in this preamble, one of the key objectives of 
today's proposed rule is ensuring that an adequate level of public 
health protection is maintained in order to minimize the risk 
associated with Cryptosporidium. While the current SWTR provides 
protection from viruses and Giardia, it does not specifically address 
Cryptosporidium, which has been linked to outbreaks resulting in over 
420,000 cases of gastrointestinal illness in the 1990s (403,000 
associated with the Milwaukee outbreak). Because of Cryptosporidium's 
resistance to disinfection practices currently in place at small 
systems throughout the country, the Agency believes enhanced filtration 
requirements are necessary to improve control of this microbial 
pathogen.
    In the IESWTR, the Agency utilized an approach consisting of three 
major components to address Cryptosporidium at plants serving 
populations of 10,000 or more. The first component required systems to 
achieve a 2 log removal of Cryptosporidium. The second component 
consisted of strengthened turbidity requirements for combined filter 
effluent. The third component required individual filter turbidity 
monitoring.
    In today's proposed rule addressing systems serving fewer than 
10,000 persons, the Agency is utilizing the same framework. Where 
appropriate, EPA has evaluated additional options in an effort to 
alleviate burden on small systems while still maintaining a comparable 
level of public health protection.
    The following sections describe the overview and purpose of each of 
the rule components, relevant data utilized during development, the 
requirements of today's proposed rule (including consideration of 
additional options where appropriate), and a request for comment 
regarding each component.
1. Two Log Cryptosporidium Removal Requirement
a. Two Log Removal
i. Overview and Purpose
    The 1998 IESWTR (63 FR 69477, December 16, 1998) establishes an 
MCLG of zero for Cryptosporidium in order to adequately protect public 
health. In conjunction with the MCLG, the IESWTR also established a 
treatment technique requiring 2 log Cryptosporidium removal for all 
surface water and GWUDI systems which filter and serve populations of 
10,000 or more people, because it was not economically and 
technologically feasible to accurately ascertain the level of 
Cryptosporidium using current analytical methods. The Agency believes 
it is appropriate and necessary to extend this treatment technique of 2 
log Cryptosporidium removal requirement to systems serving fewer than 
10,000 people.
ii. Data
    As detailed later in this section, EPA believes that the data and 
principles supporting requirements established for systems serving 
populations of 10,000 or more are also applicable to systems serving 
populations fewer than 10,000. The following section provides 
information and data regarding: (1) the estimated number of small 
systems subject to the proposed 2 log Cryptosporidium removal 
requirement; and (2) Cryptosporidium removal using various filtration 
technologies.

Estimate of the Number of Systems Subject to 2 log Cryptosporidium 
Removal Requirement

    Using the baseline described in Section III of today's proposed 
rule, the Agency applied percentages of surface water and GWUDI systems 
which filter (taken from the 1995 CWSS) in order to develop an estimate 
of the number of systems which filter and serve fewer than 10,000 
persons. This resulted in an estimated 9,133 surface water and GWUDI 
systems that filter which may be subject to the proposed removal 
requirement. Table IV.1 provides this estimate broken down by system 
size and type.

             Table IV.1.--Estimate of Systems Subject to 2 Log Cryptosporidium Removal Requirement a
----------------------------------------------------------------------------------------------------------------
                                                                  Population served
            System type            -----------------------------------------------------------------------------
                                        100        101-500      501-1K b    1K-3.3K b    3.3K-10K b  Total #Sys.
----------------------------------------------------------------------------------------------------------------
Community.........................          888         1453          950         2022         1591         6903
Non Community.....................         1099          374           78           64           35         1649
NTNC..............................          214          204           82           64           17          581
                                   -----------------------------------------------------------------------------
      Total.......................         2201         2031         1110         2150         1643     b 9134b
----------------------------------------------------------------------------------------------------------------
 a Numbers may not add due to rounding
 b K = thousands

Cryptosporidium Removal Using Conventional and Direct Filtration

    During development of the LT1FBR, the Agency reviewed the results 
of several studies that demonstrated the ability of conventional and 
direct filtration systems to achieve 2 log removal of Cryptosporidium 
at well operated plants achieving low turbidity levels. Table IV.2 
provides key information from these studies. A brief description of 
each study follows the table.

[[Page 19062]]



                         Table IV.2.--Conventional and Direct Filtration Removal Studies
----------------------------------------------------------------------------------------------------------------
        Type of treatment                 Log removal            Experimental design           Researcher
----------------------------------------------------------------------------------------------------------------
Conventional.....................  Cryptosporidium 4.2-5.2..  Pilot plants............  Patania et al. 1995
                                   Giardia 4.1-5.1..........  Pilot plants............  Patania et al. 1995
                                   Cryptosporidium 1.9-4.0..  Pilot-scale plants......  Nieminski/Ongerth 1995
                                   Giardia 2.2-3.9..........  Pilot-scale plants......  Nieminski/Ongerth 1995
                                   Cryptosporidium 1.9-2.8..  Full-scale plants.......  Nieminski/Ongerth 1995
                                   Giardia 2.8-3.7..........  Full-scale plants.......  Nieminski/Ongerth 1995
                                   Cryptosporidium 2.3-2.5..  Full-scale plants.......  LeChevallier and Norton
                                                                                         1992
                                   Giardia 2.2-2.8..........  Full-scale plants.......  ........................
                                   Cryptosporidium 2-3......  Pilot plants............  LeChevallier and Norton
                                                                                         1992
                                   Giardia and Crypto 1.5-2.  Full-scale plant          Foundation for Water
                                                               (operation considered     Research, Britain 1994
                                                               not optimized).
                                   Cryptosporidium 4.1-5.2..  Pilot Plant (optimal      Kelley et al. 1995
                                                               treatment).
                                   Cryptosporidum .2-1.7....  Pilot Plant (suboptimal   Dugan et al. 1999
                                                               treatment).              Dugan et al. 1999
Direct filtration................  Cryptosporidium 2.7-3.1..  Pilot plants............  Ongerth/Pecaroro 1995
                                   Giardia 3.1-3.5..........  Pilot plants............  Ongerth/Pecaroro 1995
                                   Cryptosporidium 2.7-5.9..  Pilot plants............  Patania et al. 1995
                                   Giardia 3.4-5.0..........  Pilot plants............  Patania et al. 1995
                                   Cryptosporidium 1.3-3.8..  Pilot plants............  Nieminski/Ongerth 1995
                                   Giardia 2.9-4.0..........  Pilot plants............  Nieminski/Ongerth 1995
                                   Cryptosporidium 2-3......  Pilot plants............  West et al. 1994
Rapid Granular Filtration (alone)  Cryptosporidium 2.3-4.9..  Pilot plant.............  Swertfeger et al., 1998
                                   Giardia 2.7-5.4..........  ........................  ........................
----------------------------------------------------------------------------------------------------------------

Patania, Nancy L, et al. 1995

    This study consisted of four pilot studies which evaluated 
treatment variables for their impact on Cryptosporidium and Giardia 
removal efficiencies. Raw water turbidities in the study ranged between 
0.2 and 13 NTU. When treatment conditions were optimized for turbidity 
and particle removal at four different sites, Cryptosporidium removal 
ranged from 2.7 to 5.9 log and Giardia removal ranged from 3.4 to 5.1 
log during stable filter operation. The median turbidity removal was 
1.4 log, whereas the median particle removal was 2 log. Median oocyst 
and cyst removal was 4.2 log. A filter effluent turbidity of 0.1 NTU or 
less resulted in the most effective cyst removal, up to 1 log greater 
than when filter effluent turbidities were greater than 0.1 NTU (within 
the 0.1 to 0.3 NTU range). Cryptosporidium removal rates of less than 
2.0 log occurred at the end of the filtration cycle.

Nieminski, Eva C. and Ongerth, Jerry E. 1995

    This 2-year study evaluated Giardia and Cryptosporidium cyst 
removal through direct and conventional filtration. The source water of 
the full scale plant had turbidities typically between 2.5 and 11 NTU 
with a maximum of 28 NTU. The source water of the pilot plant typically 
had turbidities of 4 NTU with a maximum of 23 NTU. For the pilot plant 
achieving filtered water turbidities between 0.1-0.2 NTU, 
Cryptosporidium removals averaged 3.0 log for conventional treatment 
and 3.0 log for direct filtration, while the respective Giardia 
removals averaged 3.4 log and 3.3 log. For the full scale plant 
achieving similar filtered water turbidities, Cryptosporidium removal 
averaged 2.25 log for conventional treatment and 2.8 log for direct 
filtration, while the respective Giardia removals averaged 3.3 log for 
conventional treatment and 3.9 log for direct filtration. Differences 
in performance between direct filtration and conventional treatment by 
the full scale plant were attributed to differences in source water 
quality during the filter runs.

Ongerth, Jerry E. and Pecaroro, J.P. 1995

    A 1 gallon per minute (gpm) pilot scale water filtration plant was 
used to measure removal efficiencies of Cryptosporidium and Giardia 
using very low turbidity source waters (0.35 to 0.58 NTU). With optimal 
coagulation, 3 log removal for both pathogens were obtained. In one 
test run, where coagulation was intentionally sub-optimal, the removals 
were only 1.5 log for Cryptosporidium and 1.3 log for Giardia. This 
demonstrates the importance of proper coagulation for cyst removal even 
though the effluent turbidity was less than 0.5 NTU.

LeChevallier, Mark W. and Norton, William D. 1992

    The purpose of this study was to evaluate the relationships among 
Giardia, Cryptosporidium, turbidity, and particle counts in raw water 
and filtered water effluent samples at three different systems. Source 
water turbidities ranged from less than 1 to 120 NTU. Removals of 
Giardia and Cryptosporidium (2.2 to 2.8 log) were slightly less than 
those reported by other researchers, possibly because full scale plants 
were studied under less ideal conditions than the pilot plants. The 
participating treatment plants operated within varying stages of 
treatment optimization. The median removal achieved was 2.5 log for 
Cryptosporidium and Giardia.

LeChevallier, Mark W.; Norton, William D.; and Lee, Raymond G. 1991b

    This study evaluated removal efficiencies for Giardia and 
Cryptosporidium in 66 surface water treatment plants in 14 States and 1 
Canadian province. Most of the utilities achieved between 2 and 2.5 log 
removals for both Giardia and Cryptosporidium. When no oocysts were 
detected in the finished water, occurrence levels were assumed at the 
detection limit for calculating removal efficiencies.

Foundation for Water Research 1994

    This study evaluated Cryptosporidium removal efficiencies for 
several treatment processes (including conventional filtration) using a 
pilot plant and bench-scale testing. Raw water turbidity ranged from 1 
to 30 NTU. Cryptosporidium oocyst removal was between 2 and 3 log using 
conventional filtration. Investigators

[[Page 19063]]

concluded that any measure which reduced filter effluent turbidity 
should reduce risk from Cryptosporidium, and also showed the importance 
of selecting proper coagulants, dosages, and treatment pH. In addition 
to turbidity, increased color and dissolved metal ion coagulant 
concentration in the effluent are indicators of reduced efficiency of 
coagulation/flocculation and possible reduced oocysts removal 
efficiency.

Kelley, M.B. et al. 1995

    This study evaluated two U.S. Army installation drinking water 
treatment systems for the removal of Giardia and Cryptosporidium. 
Protozoa removal was between 1.5 and 2 log. The authors speculated that 
this low Cryptosporidium removal efficiency occurred because the 
coagulation process was not optimized, although the finished water 
turbidity was less than 0.5 NTU.

West, Thomas; et al. 1994

    This study evaluated the removal efficiency of Cryptosporidium 
through direct filtration using anthracite mono-media at filtration 
rates of 6 and 14 gpm/sq.ft. Raw water turbidity ranged from 0.3 to 0.7 
NTU. Removal efficiencies for Cryptosporidium at both filtration rates 
were 2 log during filter ripening (despite turbidity exceeding 0.2 
NTU), and 2 to 3 log for the stable filter run. Log removal declined 
significantly during particle breakthrough. When effluent turbidity was 
less than 0.1 NTU, removal typically exceeded 2 log. Log removals of 
Cryptosporidium generally exceeded that for particle removal.

Swertfeger et al., 1998

    The Cincinnati Water Works conducted a 13 month pilot study to 
determine the optimum filtration media and depth of the media to 
replace media at its surface water treatment plant. The study 
investigated cyst and oocyst removal through filtration alone 
(excluding chemical addition, mixing, or sedimentation) and examined 
sand media, dual media, and deep dual media. Cyst and oocyst removal by 
each of the media designs was > 2.5 log by filtration alone.

Dugan et al., 1999

    EPA conducted pilot scale experiments to assess the ability of 
conventional treatment to control Cryptosporidium oocysts under steady 
state conditions. The work was performed with a pilot plant designed to 
minimize flow rates and the number of oocysts required for spiking. 
With proper coagulation control, the conventional treatment process 
achieved at least 2 log removal of Cryptosporidium. In all cases where 
2 log removal was not achieved, the plant also did not comply with the 
IESWTR filter effluent turbidity requirements.
    All of the studies described above indicate that rapid granular 
filtration, when operated under appropriate coagulation conditions and 
optimized to achieve a filtered water turbidity level of less than 0.3 
NTU, should achieve at least 2 log of Cryptosporidium removal. Removal 
rates vary widely, up to almost 6 log, depending upon water matrix 
conditions, filtered water turbidity effluent levels, and where and 
when removal efficiencies are measured within the filtration cycle. The 
highest log pathogen removal rates occurred in those pilot plants and 
systems which achieved very low finished water turbidities (less than 
0.1 NTU). Other key points related to the studies include:
     As turbidity performance improves for treatment of a 
particular water, there tends to be greater removal of Cryptosporidium.
     Pilot plant study data in particular indicate high 
likelihood of achieving at least 2 log removal when plant operation is 
optimized to achieve low turbidity levels. Moreover, pilot studies 
represented in Table IV.2.a tend to be for low-turbidity waters, which 
are considered to be the most difficult to treat regarding particulate 
removal and associated protozoan removal.
     Because high removal rates were demonstrated in pilot 
studies using lower-turbidity source waters, it is likely that similar 
or higher removal rates can be achieved for higher-turbidity source 
waters.
     Determining Cryptosporidium removal in full-scale plants 
can be difficult due to the fact that data includes many non-detects in 
the finished water. In these cases, finished water concentration levels 
are assigned at the detection limit and are likely to result in over-
estimation of oocysts in the finished water. This tends to under-
estimate removal levels.
     Another factor that contributes to differences among the 
data is that some of the full-scale plant data comes from plants that 
are not optimized, but meet existing SWTR requirements. In such cases, 
oocyst removal may be less than 2 log. In those studies that indicate 
that full-scale plants are achieving greater than 2 log removal 
(LeChevallier studies in particular), the following characteristics 
pertain:

--Substantial numbers of filtered water measurements resulted in oocyst 
detections;
--Source water turbidity tended to be relatively high compared to some 
of the other studies; and
--A significant percentage of these systems were also achieving low 
filtered water turbidities, substantially less than 0.5 NTU.

    Removal of Cryptosporidium can vary significantly in the 
course of the filtration cycle (i.e., at the start-up and end of filter 
operations versus the stable period of operation).

Cryptosporidium Removal Using Slow Sand and Diatomaceous Earth 
Filtration

    During development of the IESWTR, the Agency also evaluated several 
studies which demonstrated that slow sand and diatomaceous earth 
filtration were capable of achieving at least 2 log removal of 
Cryptosporidium. Table IV.3 provides key information from these 
studies. A brief description of each study follows the table.

                    Table IV.3.--Slow Sand and Diatomaceous Earth Filtration Removal Studies
----------------------------------------------------------------------------------------------------------------
        Type of treatment                 Log removal            Experimental design           Researcher
----------------------------------------------------------------------------------------------------------------
Slow-sand filtration.............  Giardia & Cryptosporidium  Pilot plant at 4.5 to     Shuler and Ghosh 1991.
                                    > 3.                       16.5 deg.C..             imms et. al. 1995.
                                   Cryptosporidium 4.5......  Full-scale plant........
Diatomaceous earth filtration....  Giardia & Cryptosporidium  Pilot plant,............  Shuler et. al. 1990.
                                    > 3.                      Bench scale.............  Ongerth & Hutton, 1997.
                                   Cryptosporidium 3.3-6.68.
----------------------------------------------------------------------------------------------------------------

Shuler and Ghosh 1991

    This pilot study was conducted to evaluate the ability of slow sand 
filters to remove Giardia, Cryptosporidium, coliforms, and turbidity. 
The pilot study was conducted at Pennsylvania State University using a 
raw water source with a turbidity ranging from 0.2-0.4 NTU. Influent 
concentration of

[[Page 19064]]

Cryptosporidium oocysts during the pilot study ranged from 1,300 to 
13,000 oocysts/gallon. Oocyst removal was shown to be greater than 4 
log.

Timms et al 1995

    This pilot study was conducted to evaluate the efficiency of slow 
sand filters at removing Cryptosporidium. A pilot plant was constructed 
of 1.13 m\2\ in area and 0.5 m in depth with a filtration rate of 0.3m/
h. The filter was run for 4-5 weeks before the experiment to ensure 
proper operation. Cryptosporidium oocysts were spiked to a 
concentration of 4,000/L. Results of the study indicated a 4.5 log 
removal of Cryptosporidium oocysts.

Shuler et al 1990

    In this study, diatomaceous earth (DE) filtration was evaluated for 
removal of Giardia, Cryptosporidium, turbidity and coliform bacteria. 
The study used a 0.1m\2\ pilot scale DE filter with three grades of 
diatomaceous earth (A, B, and C). The raw water turbidity varied 
between 0.1 and 1 NTU. Filter runs ranged from 2 days to 34 days. A 
greater than 3 log removal of Cryptosporidium was demonstrated in the 9 
filter runs which made up the study.

Ongerth and Hutton, 1997

    Bench scale studies were used to define basic characteristics of DE 
filtration as a function of DE grade and filtration rate. Three grades 
of DE were used in the tests. Cryptosporidium removal was measured by 
applying river water seeded with Cryptosporidium to Walton test 
filters. Tests were run for filtration rates of 1 and 2 gpm/sq ft. Each 
run was replicated 3 times. Approximately 6 logs reduction in the 
concentration of Cryptosporidium oocysts was expected under normal 
operating conditions.

Cryptosporidium Removal Using Alternative Filtration Technologies

    EPA recognizes that systems serving fewer than 10,000 individuals 
employ a variety of filtration technologies other than those previously 
discussed. EPA collected information regarding several other popular 
treatment techniques in an effort to verify that these treatments were 
also technically capable of achieving a 2 log removal of 
Cryptosporidium. A brief discussion of these alternative technologies 
follows along with studies demonstrating effective Cryptosporidium 
removals.

Membrane Filtration

    Membrane filtration (Reverse Osmosis, Nanofiltration, 
Ultrafiltration, and Microfiltration) relies upon pore size in order to 
remove particles from water. Membranes possess a pore size smaller than 
that of a Cryptosporidium oocyst, enabling them to achieve effective 
log removals. The smaller the pore size, the more effective the rate of 
removal. Typical pore sizes for each of the four types of membrane 
filtration are shown below:
     Microfiltration--1-0.1 microns (m)
     Ultrafiltration--0.1-.01 (m)
     Nanofiltration--.01-.001 (m)
     Reverse Osmosis--.001 (m)

Bag Filtration

    Bag filters are non-rigid, disposable, fabric filters where water 
flows from inside of the bag to the outside of the bag. One or more 
filter bags are contained within a pressure vessel designed to 
facilitate rapid change of the filter bags when the filtration capacity 
has been used up. Bag filters do not generally employ any chemical 
coagulation. The pore sizes in the filter bags designed for protozoa 
removal generally are small enough to remove protozoan cysts and 
oocysts but large enough that bacteria, viruses and fine colloidal 
clays would pass through. Bag filter studies have shown a significant 
range of results in the removal of Cryptosporidium oocysts (0.33-3.2 
log). (Goodrich, 1995)

Cartridge Filtration

    Cartridge filtration also relies on physical screening to remove 
particles from water. Typical cartridge filters are pressure filters 
with glass, fiber or ceramic membranes, or strings wrapped around a 
filter element housed in a pressure vessel (USEPA, 1997a).
    The Agency evaluated several studies which demonstrate the ability 
of various alternative filtration technologies to achieve 2 log removal 
of Cryptosporidium ( in several studies 2 log removal of 4-5 
(m) microspheres were used as a surrogate for 
Cryptosporidium). These studies demonstrate that 2 log removal was 
consistently achievable in all but bag filters. Table IV.4 provides key 
information from these studies. A brief description of each study 
follows:

                               Table IV.4.--Alternative Filtration Removal Studies
----------------------------------------------------------------------------------------------------------------
        Type of treatment                 Log removal            Experimental design           Researcher
----------------------------------------------------------------------------------------------------------------
Microfiltration..................  Cryptosporidium 4.2-4.9    Bench Scale.............  Jacangelo et al. 1997.
                                    log.
                                   Giardia 4.6-5.2 log......                            ........................
                                   Cryptosporidium 6.0--7.0   Pilot Plant.............  ........................
                                    log.
                                   Cryptosporidium 4.3--5.0   Pilot Plant.............  Drozd & Schartzbrod,
                                    log.                                                 1997.
                                   Cryptosporidium 7.0-7.7    Bench Scale.............  Hirata & Hashimoto,
                                    log.                                                 1998.
                                   Microspheres 3.57-3.71     Full Scale..............  Goodrich et al. 1995.
                                    log.
Ultrafiltration..................  Cryptosporidium 4.4--4.9   Bench Scale.............  Jacangelo et al. 1997.
                                    log.
                                   Giardia 4.7-5.2 log......                            ........................
                                   Cryptosporidium 5.73-5.89  Bench Scale.............  Collins et al. 1996.
                                    log.
                                   Giardia 5.75-5.85 log....                            ........................
                                   Cryptosporidium 7.1-7.4    Bench Scale.............  Hirata & Hashimoto,
                                    log.                                                 1998.
                                   Cryptosporidium 3.5 log..  pilot Plant.............  Lykins et al. 1994.
                                   Microspheres 3-4 log.....
Reverse Osmosis..................  Cryptosporidium > 5.7 log  Pilot Scale.............  Adham et al. 1998
                                   Giardia > 5.7 log........
Hybrid Membrane..................  Microspheres 4.18 log....  Bench Scale.............  Goodrich et al. 1995
Bag Filtration...................  Microspheres .33-3.2 log.  Pilot Plant.............  Goodrich et al. 1995
Cartridge filtration.............  Microspheres 3.52-3.68     Pilot Plant.............  Goodrich et al. 1995
                                    log.                      Bench Scale.............  Land, 1998.
                                   Particles (5-15 um) > 2
                                    log.
----------------------------------------------------------------------------------------------------------------


[[Page 19065]]

Jacangelo et al., 1997

    Bench scale and pilot plant tests were conducted with 
microfiltration and ultrafiltration filters (using six different 
membranes) in order to evaluate microorganism removal. Bench scale 
studies were conducted under worst case operating conditions (direct 
flow filtration at the maximum recommended transmembrane pressure using 
deionized water slightly buffered at pH 7). Log removal ranged from 4.7 
to 5.2 log removal. Pilot plant results ranged from 6.0-7.0 log removal 
during worst-case operating conditions (i.e., direct filtration 
immediately after backwashing at the maximum recommended operating 
transmembrane pressure).

Drozd and Schartzbrod, 1997

    A pilot plant system was established to evaluate the removal of 
Cryptosporidium using crossflow microfiltration (.2 m 
porosity). Results demonstrated Cryptosporidium log removals of 4.3 to 
greater than 5.5 with a corresponding mean filtrate turbidity of 0.25 
NTU.

Collins et. al., 1996

    This study consisted of bench scale testing of Cryptosporidium and 
Giardia log removals using an ultrafiltration system. Log removal of 
Cryptosporidium ranged from 5.73 to 5.89 log, while removal of Giardia 
ranged from 5.75 to 5.85 log.

Hirata & Hashimoto, 1998

    Pilot scale testing using microfiltration (nominal pore size of .25 
m) and ultrafiltration (nominal cut-off molecular weight (MW) 
13,000 daltons) was conducted to determine Cryptosporidium oocyst 
removal. Results conducted on the ultrafiltration units ranged from 7.1 
to 7.5 logs of Cryptosporidium removal. Results of the microfiltration 
studies yielded log removals from 7.0 to 7.7 log.

Lykins et al., [1994]

    An ultrafiltration system was evaluated for the removal of 
Cryptosporidium oocysts at the USEPA Test and Evaluation Facility in 
Cincinnati, Ohio. The filter run was just over 48 hours. A 3.5 log 
removal of Cryptosporidium oocysts was observed. Additionally, twenty-
four experiments were performed using 4.5 m polystyrene 
microspheres as a surrogate for Cryptosporidium because of a similar 
particle distribution. Log removal of microspheres ranged from 3 to 4 
log.

Adham et al., 1998

    This study was conducted to evaluate monitoring methods for 
membrane integrity. In addition to other activities, microbial 
challenge tests were conducted on reverse osmosis (RO) membranes to 
both determine log removals and evaluate system integrity. Log removal 
of Cryptosporidium and Giardia was >5.7 log in uncompromised 
conditions, and > 4.5 log in compromised conditions.

Goodrich et al., 1995

    This study was conducted to evaluate removal efficiencies of three 
different bag filtration systems. Average filter pore size of the 
filters was 1 m while surface area ranged from 35 to 47 sq ft. 
Bags were operated at 25, 50 and 100 percent of their maximum flow rate 
while spiked with 4.5 m polystyrene microspheres (beads) as a 
surrogate for Cryptosporidium. Bead removal ranged from .33 to 3.2 log 
removal.

Goodrich et al 1995.

    This study evaluated a cartridge filter with a 2 m rating 
and 200 square feet of surface area for removal efficiency of 
Cryptosporidium sized particles. The filter was challenge tested with 
4.5 m polystyrene microspheres as a surrogate for 
Cryptosporidium. Flow was set at 25 gpm with 50 psi at the inlet. 
Results from two runs under the same conditions exhibited log removals 
of 3.52 and 3.68.

Land, 1998

    An alternative technology demonstration test was conducted to 
evaluate the ability of a cartridge filter to achieve 2 log removal of 
particles in the 5 to 15 m range. The cartridge achieved at 
least 2 log removal of the 5 to 25 m particles 95 percent of 
the time up to a 20 psi pressure differential. The filter achieved at 
least 2 log removal of 5 to 15 m particles up to 30-psi 
pressure differential.
    While the studies above note that alternative filtration 
technologies have demonstrated in the lab the capability to achieve a 2 
log removal of Cryptosporidium, the Agency believes that the 
proprietary nature of these technologies necessitates a more rigorous 
technology-specific determination be made. Given this issue, the Agency 
believes that its Environmental Technology Verification (ETV) Program 
can be utilized to verify the performance of innovative technologies. 
Managed by EPA's Office of Research and Development, ETV was created to 
substantially accelerate the entrance of new environmental technologies 
into the domestic and international marketplace. ETV consists of 12 
pilot programs, one of which focuses on drinking water. The program 
contains a protocol for physical removal of microbiological and 
particulate contaminants, including test plans for bag and cartridge 
filters and membrane filters (NSF, 1999). These protocols can be 
utilized to determine whether a specific alternative technology can 
effectively achieve a 2 log removal of Cryptosporidium, and under what 
parameters that technology must be operated to ensure consistent levels 
of removal. Additional information on the ETV program can be found on 
the Agency's website at http://www.epa.gov/etv.
iii. Proposed Requirements
    Today's proposed rule establishes a requirement for 2 log removal 
of Cryptosporidium for surface water and GWUDI systems serving fewer 
than 10,000 people that are required to filter under the SWTR. 
Compliance with the combined filter effluent turbidity requirements, as 
described later, ensures compliance with the 2 log removal requirement. 
The requirement for a 2 log removal of Cryptosporidium applies between 
a point where the raw water is not subject to recontamination by 
surface water runoff and a point downstream before or at the first 
customer.
iv. Request for Comments
    EPA requests comment on the 2 log removal requirement as discussed. 
The Agency is also soliciting public comment and data on the ability of 
alternative filtration technologies to achieve 2 log Cryptosporidium 
removal.
2. Turbidity Requirements
a. Combined Filter Effluent
i. Overview and Purpose
    In order to address concern with Cryptosporidium, EPA has analyzed 
log removal performance by well operated plants (as described in the 
previous section) as well as filter performance among small systems to 
develop an appropriate treatment technique requirement that assures an 
increased level of Cryptosporidium removal. In evaluating combined 
filter performance requirements, EPA considered the strengthened 
turbidity provisions within the IESWTR and evaluated whether these were 
appropriate for small systems as well.
ii. Data
    In an effort to evaluate combined filter effluent (CFE) 
requirements, EPA collected data in several areas to

[[Page 19066]]

supplement existing data, and address situations unique to smaller 
systems. This data includes:
     An estimate of the number of systems subject to the 
proposed strengthened turbidity requirements;
     Current turbidity levels at systems throughout the U.S. 
serving populations fewer than 10,000;
     The ability of package plants to meet strengthened 
turbidity standards; and
     The correlation between meeting CFE requirements and 
achieving 2 log removal of Cryptosporidium.

Estimate of the Number of Systems Subject to Strengthened CFE Turbidity 
Standards

    Using the estimate of 9,134 systems which filter and serve fewer 
than 10,000 persons (as described in Section IV.A.1 of today's 
proposal), the Agency used the information contained within the CWSS 
database to estimate the number of systems which utilized specific 
types of filtration. The data was segregated based on the type of 
filtration utilized and the population size of the system. Percentages 
were derived for each of the following types of filtration:
     Conventional and Direct Filtration;
     Slow Sand Filtration;
     Diatomaceous Earth Filtration; and
     Alternative Filtration Technologies.
    The percentages were applied to the estimate discussed in Section 
IV.A.1 of today's proposal for each of the respective population 
categories. Based on this analysis, the Agency estimates 5,896 
conventional and direct filtration systems will be subject to the 
strengthened combined filter effluent turbidity standards. EPA 
estimates 1,756 systems utilize slow sand or diatomaceous earth 
filtration, and must continue to meet turbidity standards set forth in 
the SWTR. The remaining 1,482 systems are estimated to use alternative 
filtration technologies and will be required to meet turbidity 
standards as set forth by the State upon analysis of a 2 log 
Cryptosporidium demonstration conducted by the system.

Current Turbidity Levels

    EPA has developed a data set which summarizes the historical 
turbidity performance of various filtration plants serving populations 
fewer than 10,000 (EPA, 1999d). The data set represents those systems 
that were in compliance with the turbidity requirements of the SWTR 
during all months being analyzed. The data set consists of 167 plants 
from 15 States. Table IV.5 provides information regarding the number of 
plants from each State. The data set includes plants representing each 
of the five population groups utilized in the CWSS (25-100, 101-500, 
501-1,000, 1,001-3,300, and 3,301-10,000). The Agency has also received 
an additional data set from the State of California (EPA, 2000). This 
data has not been included in the assessments described below. The 
California data demonstrates similar results to the larger data set 
discussed below.

            Table IV.5.--Summary of LT1FBR Turbidity Data Set
------------------------------------------------------------------------
                                                              Number of
                           State                                Plants
------------------------------------------------------------------------
Alabama....................................................            1
California.................................................            1
Colorado...................................................           16
Illinois...................................................           13
Kansas.....................................................           20
Louisiana..................................................            6
Minnesota..................................................            3
Montana....................................................            2
North Carolina.............................................           16
Ohio.......................................................            4
Pennsylvania...............................................           27
South Carolina.............................................           16
Texas......................................................           23
Washington.................................................           17
West Virginia..............................................            2
                                                            ------------
    Total..................................................         167
------------------------------------------------------------------------
(EPA, 1999d)

    This data was evaluated to assess the national impact of modifying 
existing turbidity requirements. The current performance of plants was 
assessed with respect to the number of months in which selected 95th 
percentile and maximum turbidity levels were met. The data show that 
approximately 88 percent of systems are also currently meeting the new 
requirements of a maximum turbidity limit of 1 NTU (Figure IV.1). With 
respect to the 95th percentile turbidity limit, roughly 46 percent of 
these systems are currently meeting the new requirement of 0.3 NTU 
(Figure IV.2) while approximately 70 percent meet this requirement 9 
months out of the year. Estimates for systems needing to make changes 
to meet a turbidity performance limit of 0.3 NTU were based on the 
ability of systems currently to meet a 0.2 NTU. This assumption was 
intended to take into account a utility's concern with possible 
turbidity measurement error and to reflect the expectation that a 
number of utilities will attempt to achieve finished water turbidity 
levels below the regulatory performance level to assure compliance.
    As depicted in Figure IV.1 and IV.2, the tighter turbidity 
performance standards for combined filter effluent in today's proposed 
rule reflect the actual, current performance many systems already 
achieve nationally. Revising the turbidity criteria effectively ensures 
that these systems continue to perform at their current level while 
also improving performance of a substantial number of systems that 
currently meet existing SWTR criteria, but operate at turbidity levels 
higher than proposed in today's rule.

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Package Plants

    During development of today's proposed rule, some stakeholders 
expressed concern regarding the ability of ``package plants'' to meet 
the proposed requirements. EPA evaluated these systems by gathering 
data from around the country. The information affirms the Agency's 
belief that package plants can and currently do meet the turbidity 
limits in today's proposed rule.
    Package plants combine the processes of rapid mixing, flocculation, 
sedimentation and filtration (rapid sand, mixed or dual media filters) 
into a single package system. Package Filtration Plants are 
preconstructed, skid mounted and transported virtually assembled to the 
site. The use of tube settlers, plate settlers, or adsorption 
clarifiers in some Package Filtration Plants results in a compact size 
and more treatment capacity.
    Package Filtration Plants are appropriate for treating water of a 
fairly consistent quality with low to moderate turbidity. Effective 
treatment of source waters containing high levels of or extreme 
variability in turbidity levels requires skilled operators and close 
operational attention. High turbidity or excessive color in the source 
water could require chemical dosages above the manufacturer's 
recommendations for the particular plant. Excessive turbidity levels 
may require presedimentation or a larger capacity plant. Specific 
design criteria of a typical package plant and operating and 
maintenance requirements can vary, but an example schematic is depicted 
in Figure IV.3.

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    The Agency believes that historic data show that package plants 
have a comparable ability to meet turbidity requirements as 
conventional or direct filtration systems.
    A 1987 report of pilot testing using a trailer-mounted package 
plant system to treat raw water from Clear Lake in Lakeport, California 
demonstrates the ability of such systems to achieve low turbidity 
requirements. The raw water contained moderate to high turbidity (18 to 
103 NTU). Finished water turbidities ranged from 0.07 to 0.11 NTU (EPA, 
1987). Two previous studies (USEPA, 1980a,b and Cambell et al., 1995) 
also illustrate the ability of package systems throughout the country 
to meet historic turbidity performance criteria. These studies are 
described briefly:

Package Water Treatment Plant Performance Evaluation (USEPA, 1980a,b)

    The Agency conducted a study of package water treatment systems 
which encompassed 36 plants in Kentucky, West Virginia, and Tennessee. 
Results from that study showed that the plants could provide water that 
met the existing turbidity limits established under the National 
Interim Primary Drinking Water Standards. Of the 31 plants at which 
turbidity measurements were made, 23 (75 percent) were found to be 
meeting existing standards. Of the 8 which did not meet requirements, 
one did not use chemical coagulants, and 6 operated less than four 
hours per day. (USEPA, 1980a, b)

Package Plants for Small Systems: A Field Study (Cambell et al, 1995)

    This 1992 project evaluated the application of package plant 
technology to small communities across the U.S. The project team 
visited 48 facilities across the U.S. Of the 29 surface water and GWUDI 
systems, 21 (72 percent) had grab turbidity samples less than 0.5 NTU, 
the 95 percent limit which became effective in June of 1993. Twelve 
systems (41 percent) had values less than today's proposed 0.3 NTU 95 
percent turbidity limit. (Cambell et al., 1995) It should be noted that 
today's rule requires compliance with turbidity limits based on 4 hour 
measurments.
    The Agency recently evaluated Filter Plant Performance Evaluations 
(FPPEs) conducted by the State of Pennsylvania, in an effort to 
quantify the comparative abilities of package plants and conventional 
filtration systems to meet the required turbidity limits. The data set 
consisted of 100 FPPEs conducted at systems serving populations fewer 
than 10,000 (PADEP, 1999). Thirty-seven FPPEs were conducted at 
traditional conventional filtration systems while 37 were conducted at 
package plants or ``pre-engineered'' systems. The remaining 26 systems 
utilized other filtration technologies.
    The FPPEs provided a rating of either acceptable or unacceptable as 
determined by the evaluation team. This rating was based on an 
assessment of the capability of individual unit processes to 
continuously provide an effective barrier to the passage of 
microorganisms. Specific performance goals were utilized to evaluate 
the performance of the system including the consistent ability to 
produce a finished water turbidity of less than 0.1 NTU, which is lower 
than the combined filter effluent turbidity requirement in today's 
proposed rule. Seventy-three percent of the traditional conventional 
filtration systems were rated acceptable and 89 percent of the package 
plants were rated acceptable.
    The Agency also evaluated historic turbidity data graphs contained 
within each FPPE to provide a comparison of the ability of package 
plants and conventional systems to meet the 1 NTU max and 0.3 NTU 95 
percent requirements that are contained in today's proposed rule. 
Sixty-seven percent of the conventional systems would meet today's 
proposed requirements while 74 percent of package systems in the data 
set would meet today's proposed requirements. The Agency believes that, 
when viewed alongside the aforementioned studies (USEPA, 1980a,b and 
Cambell et al., 1995), it is apparent that package systems have the 
ability to achieve more stringent turbidity limits.

Correlation Between CFE Requirements and 2-log Cryptosporidium Removal

    Recent pilot scale experiments performed by the Agency assessed the 
ability of conventional treatment to control Cryptosporidium under 
steady state conditions. The work was performed with a pilot plant that 
was designed to minimize flow rates and as a result the number of 
oocyst required for continuous spiking. (Dugan et al. 1999)
    Viable oocysts were fed into the plant influent at a concentration 
of 106/L for 36 to 60 hours. The removals of oocysts and the 
surrogate parameters turbidity, total particle counts and aerobic 
endospores were measured through sedimentation and filtration. There 
was a positive correlation between the log removals of oocysts and all 
surrogate parameters through the coagulation and settling process. With 
proper coagulation control, the conventional treatment process achieved 
the 2 log total Cryptosporidium removal required by the IESWTR. In all 
cases where 2 log total removal was not achieved, the plant also did 
not comply with the IESWTR's CFE turbidity requirements. Table IV.6 
provides information on Cryptosporidium removals from this study.

         Table IV.6.--Log Removal of Oocysts (Dugan et al. 1999)
------------------------------------------------------------------------
                                   Log removal
               Run                    crypto    Exceeds CFE requirements
------------------------------------------------------------------------
1................................          4.5  No.
2................................          5.2  No.
3................................          1.6  Yes, average CFE 2.1
                                                 NTU.
4................................          1.7  Yes, only 88% CFE under
                                                 0.3 NTU.
5................................          4.1  No.
6................................          5.1  No.
7................................          0.2  Yes, average CFE 0.5
                                                 NTU.
8................................          0.5  Yes, only 83% CFE under
                                                 0.3 NTU.
9................................          5.1  No.
10...............................          4.8  No.
------------------------------------------------------------------------


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iii. Proposed Requirements

    Today's proposed rule establishes combined filter effluent 
turbidity requirements which apply to all surface water and GWUDI 
systems which filter and serve populations fewer than 10,000. For 
conventional and direct filtration systems, the turbidity level of 
representative samples of a system's combined filter effluent water 
must be less than or equal to 0.3 NTU in at least 95 percent of the 
measurements taken each month. The turbidity level of representative 
samples of a system's filtered water must not exceed 1 NTU at any time.
    For membrane filtration, (microfiltration, ultrafiltration, 
nanofiltration, and reverse osmosis) the Agency is proposing to require 
that the turbidity level of representative samples of a system's 
combined filter effluent water must be less than or equal to 0.3 NTU in 
at least 95 percent of the measurements taken each month. The turbidity 
level of representative samples of a system's filtered water must not 
exceed 1 NTU at any time. EPA included turbidity limits for membrane 
systems to allow such systems the ability to opt out of a possible 
costly demonstration of the ability to remove Cryptosporidium. The 
studies displayed previously in Table IV.4, demonstrate the ability of 
these technologies to achieve log-removals in excess of 2 log. In lieu 
of these turbidity limits, a public water system which utilizes 
membrane filtration may demonstrate to the State for purposes of 
membrane approval (using pilot plant studies or other means) that 
membrane filtration in combination with disinfection treatment 
consistently achieves 3 log removal and/or inactivation of Giardia 
lamblia cysts, 4 log removal and/or inactivation of viruses, and 2 log 
removal of Cryptosporidium oocysts. For each approval, the State will 
set turbidity performance requirements that the system must meet at 
least 95 percent of the time and that the system may not exceed at any 
time at a level that consistently achieves 3 log removal and/or 
inactivation of Giardia lamblia cysts, 4 log removal and/or 
inactivation of viruses, and 2 log removal of Cryptosporidium oocysts.
    Systems utilizing slow sand or diatomaceous earth filtration must 
continue to meet the combined filter effluent limits established for 
these technologies under the SWTR (found in Sec. 141.73 (b) and (c)). 
Namely, the turbidity level of representative samples of a system's 
filtered water must be less than or equal to 1 NTU in at least 95 
percent of the measurements taken each month and the turbidity level of 
representative samples of a system's filtered water must at no time 
exceed 5 NTU.
    For all other alternative filtration technologies (those other than 
conventional, direct, slow sand, diatomaceous earth, or membrane), 
public water systems must demonstrate to the State for purposes of 
approval (using pilot plant studies or other means), that the 
alternative filtration technology in combination with disinfection 
treatment, consistently achieves 3 log removal and/or inactivation of 
Giardia lamblia cysts, 4 log removal and/or inactivation of viruses, 
and 2 log removal of Cryptosporidium oocysts. For each approval, the 
State will set turbidity performance requirements that the system must 
meet at least 95 percent of the time and that the system may not exceed 
at any time at a level that consistently achieves 3 log removal and/or 
inactivation of Giardia lamblia cysts, 4 log removal and/or 
inactivation of viruses, and 2 log removal of Cryptosporidium oocysts.

iv. Request for Comments

    EPA solicits comment on the proposal to require systems to meet the 
proposed combined filter effluent turbidity requirements. Additionally, 
EPA solicits comment on the following:
     The ability of package plants and/or other unique 
conventional and/or direct systems to meet the combined filter effluent 
requirements;
     Microbial attachment to particulate material or inert 
substances in water systems may have the effect of providing 
``shelter'' to microbes by reducing their exposure to disinfectants 
(USEPA, 1999e). While inactivation of Cryptosporidium is not a 
consideration of this rule, should maximum combined filter effluent 
limits for slow sand and diatomaceous earth filtration systems be 
lowered to 1 or 2 NTU and/or 95th percentile requirements lowered to 
0.3 NTU to minimize the ability of turbidity particles to ``shelter'' 
Cryptosporidium oocysts?
     Systems which practice enhanced coagulation may produce 
higher turbidity effluent because of the process. Should such systems 
be allowed to apply to the State for alternative exceedance levels 
similar to the provisions contained in the rule for systems which 
practice lime softening?
     Issues specific to small systems regarding the proposed 
combined filter effluent requirements;
     Establishment of turbidity limits for alternative 
filtration technologies;
     Allowance of a demonstration to establish site specific 
limits in lieu of generic turbidity limits, including components of 
such demonstration; and
     The number of small membrane systems employed throughout 
the country.
    The Agency also requests comment on establishment of turbidity 
limits for membrane systems. While integrity of membranes provides the 
clearest understanding of the effectiveness of membranes, turbidity has 
been utilized as an indicator of performance (and corresponding 
Cryptosporidium log removal) for all filtration technologies. EPA 
solicits comment on modifying the requirements for membrane filters to 
meet integrity testing, as approved by the State and with a frequency 
approved by the State.
b. Individual Filter Turbidity
i. Overview and Purpose
    During development of the IESWTR, it was recognized that 
performance of individual filters within a plant were of paramount 
importance to producing low-turbidity water. Two important concepts 
regarding individual filters were discussed. First, it was recognized 
that poor performance (and potential pathogen breakthrough) of one 
filter could be masked by optimal performance in other filters, with no 
discernable rise in combined filter effluent turbidity. Second, it was 
noted that individual filters are susceptible to turbidity spikes (of 
short duration) which would not be captured by four-hour combined 
filter effluent measurements. To address the shortcomings associated 
with individual filters, EPA established individual filter monitoring 
requirements in the IESWTR. For the reasons discussed below, the Agency 
believes it appropriate and necessary to extend individual filter 
monitoring requirements to systems serving populations fewer than 
10,000 in the LT1FBR.
ii. Data
    EPA believes that the support and underlying principles regarding 
the IESWTR individual filter monitoring requirements are also 
applicable for the LT1FBR. The Agency has estimated that 5,897 
conventional and direct filtration systems will be subject to today's 
proposed individual filter turbidity requirements. Information 
regarding this estimate is found in Section IV.A.2.a of today's 
proposal. The Agency has analyzed information regarding turbidity 
spikes and filter masking which are presented next.

[[Page 19073]]

Turbidity Spikes

    During a turbidity spike, significant amounts of particulate matter 
(including Cryptosporidium oocysts, if present) may pass through the 
filter. Various factors affect the duration and amplitude of filter 
spikes, including sudden changes to the flow rate through the filter, 
treatment of the filter backwash water, filter-to-waste capability, and 
site-specific water quality conditions. Recent experiments have suggest 
that surging has a significant effect on rapid sand filtration 
performance (Glasgow and Wheatley, 1998). An example filter profile 
depicting turbidity spikes is shown in Figure IV.4.
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    Studies considered by both EPA and the M-DBP Advisory Committee 
noted that the greatest potential for a peak in turbidity (and thus, 
pathogen breakthrough) is near the beginning of the filter run after 
filter backwash or start up of operation (Amirtharajah, 1988; Bucklin, 
et al. 1988; Cleasby, 1990; and Hall and Croll, 1996). This phenomenon 
is depicted in Figure IV.4. Turbidity spikes also may occur for a 
variety of other reasons. These include:
     Outages or maintenance activities at processes within the 
treatment train;
     Coagulant feed pump or equipment failure;
     Filters being run at significantly higher loading rates 
than approved;
     Disruption in filter media;
     Excessive or insufficient coagulant dosage; and
     Hydraulic surges due to pump changes or other filters 
being brought on/off-line.
    A recent study was completed which evaluated particle removal by 
filtration throughout the country. While the emphasis of this study was 
particle counting and removal, fifty-two of the 100 plants surveyed 
were also surveyed for turbidity with on-line turbidimeters. While all 
of the plants were able to meet 0.5 NTU 95 percent of the time, it was 
noted that there was a significant occurrence of spikes during the 
filter runs. These were determined to be a major source of raising the 
95th percentile value for most of the filter runs. (McTigue et al. 
1998)
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Masking of Filter Performance

    Combined Filter Effluent monitoring can mask poor performance of 
individual filters which may allow passage of particulates (including 
Cryptosporidium oocysts). One poorly performing filter, can be 
effectively ``masked'' by other well operated filters because water 
from each of the filters is combined before an effluent turbidity 
measurement is taken. The following example illustrates this 
phenomenon.
    The fictitious City of ``Smithville'' (depicted in Figure IV.6) 
operates a conventional filtration plant with four rapid granular 
filters as shown below. Filter number 1 has significant problems 
because the depth and placement of the media are contributing to 
elevated turbidities. Filters 2, 3, and 4 do not have these problems 
and are operating properly.
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    Turbidity measurements taken at the clearwell indicate 0.3 NTU. 
Filter 4 produces water with a turbidity of 0.08 NTU, Filter 3 a 
turbidity of 0.2 NTU, Filter 2 a turbidity of 0.1 NTU, and Filter 1 a 
turbidity of 0.9 NTU. Each filter contributes an equal proportion of 
water, but each is operating at different turbidity levels which 
contributes to the combined filter effluent of 0.32 NTU. 
([0.08+0.2+0.1+0.9]4 = 0.32 NTU)
    As discussed previously in Section IV.2.a, the Agency believes that 
a system must meet 0.3 NTU 95 percent of the time an appropriate 
treatment technique requirement that assures an increased level of 
Cryptosporidium removal. While the fictitious system described above 
would barely meet the required CFE turbidity, it is entirely possible 
that they would not be achieving an overall 2 log removal of 
Cryptosporidium with one filter achieving considerably less than 2-log 
removal. This issue highlights the importance of understanding the 
performance of individual filters relative to overall plant 
performance.
iii. Proposed Requirements
    Today's proposed rule establishes an individual filter turbidity 
requirement which applies to all surface water and GWUDI systems using 
filtration and which serve populations fewer than 10,000 and utilize 
direct or conventional filtration. In developing this requirement, the 
Agency evaluated several alternatives (A, B and C) in an attempt to 
reduce the burden faced by small systems while still providing: (1) A 
comparable level of public health protection as that afforded to 
systems serving 10,000 or more people and (2) an early-warning tool 
systems can use to detect and correct problems with filters.

Alternative A

    The first alternative considered by the Agency was requiring direct 
and conventional filtration systems serving populations fewer than 
10,000 to meet the same requirements as established for systems serving 
10,000 or more people. This alternative would require that all 
conventional and direct filtration systems must conduct continuous 
monitoring of turbidity (one turbidity measurement every 15 minutes) 
for each individual filter. Systems must provide an exceptions report 
to the State as part of the existing combined filter effluent reporting 
process for any of the following circumstances:
    (1) Any individual filter with a turbidity level greater than 1.0 
NTU based on two consecutive measurements fifteen minutes apart;
    (2) Any individual filter with a turbidity greater than 0.5 NTU at 
the end of the first four hours of filter operation based on two 
consecutive measurements fifteen minutes apart;
    (3) Any individual filter with turbidity levels greater than 1.0 
NTU based on two consecutive measurements fifteen minutes apart at any 
time in each of three consecutive months (the system must, in addition 
to filing an exceptions report, conduct a self-assessment of the 
filter); and
    (4) Any individual filter with turbidity levels greater than 2.0 
NTU based on two consecutive measurements fifteen minutes apart at any 
time in each of two consecutive months (the system must file an 
exceptions report and must arrange for a comprehensive performance 
evaluation (CPE) to be conducted by the State or a third party approved 
by the State).
    Under the first two circumstances identified, a system must produce 
a filter profile if no obvious reason for the abnormal filter 
performance can be identified.

Alternative B

    The second alternative considered by the Agency represents a slight 
modification from the individual filter monitoring requirements of 
large systems. The 0.5 NTU exceptions report trigger would be omitted 
in an effort to reduce the burden associated with daily data 
evaluation. Additionally, the filter profile requirement would be 
removed. Requirement language was slightly modified in an effort to 
simplify the requirement for small system operators. This alternative 
would still require that all conventional and direct filtration systems 
conduct continuous monitoring (one turbidity measurement every 15 
minutes) for each individual filter, but includes the following three 
requirements:
    (1) A system must provide an exceptions report to the State as part 
of the existing combined effluent reporting process if any individual 
filter turbidity measurement exceeds 1.0 NTU (unless the system can 
show that the next reading is less than 1.0 NTU);
    (2) If a system is required to submit an exceptions report for the 
same filter in three consecutive months, the system must conduct a 
self-assessment of the filter.
    (3) If a system is required to submit an exceptions report for the 
same filter in two consecutive months which contains an exceedance of 
2.0 NTU by the same filter, the system must arrange for a CPE to be 
conducted by the State or a third party approved by the State.

Alternative C

    The third alternative considered by the Agency would include new 
triggers for reporting and follow-up action in an effort to reduce the 
daily burden associated with data review. This alternative would still 
require that all conventional and direct filtration systems must 
conduct continuous monitoring (one turbidity measurement every 15 
minutes) for each individual filter, but would include the following 
three requirements:
    (1) A system must provide an exceptions report to the State as part 
of the existing combined effluent reporting process if filter samples 
exceed 0.5 NTU in at least 5 percent of the measurements taken each 
month and/or any individual filter measurement exceeds 2.0 NTU (unless 
the system can show that the following reading was   2.0 NTU).
    (2) If a system is required to submit an exceptions report for the 
same filter in three consecutive months the system must conduct a self-
assessment of the filter.
    (3) If a system is required to submit an exceptions report for the 
same filter in two consecutive months which contains an exceedance of 
2.0 NTU by the same filter, the system must arrange for a CPE to be 
conducted by the State or a third party approved by the State.
    For all three alternatives the requirements regarding self 
assessments and CPEs are the same. If a CPE is required, the system 
must arrange for the State or a third party approved by the State to 
conduct the CPE no later than 30 days following the exceedance. The CPE 
must be completed and submitted to the State no later than 90 days 
following the exceedance which triggered the CPE. If a self-assessment 
is required it must take place within 14 days of the exceedance and the 
system must report to the State that the self-assessment was conducted. 
The self assessment must consist of at least the following components:
     assessment of filter performance;
     development of a filter profile;
     identification and prioritization of factors limiting 
filter performance;
     assessment of the applicability of corrections; and
     preparation of a filter self assessment report.
    In considering each of the above alternatives, the Agency attempted 
to reduce the burden faced by small systems. Each of the three 
alternatives was judged to provide levels of public health protection 
comparable to those in the IESWTR for large systems. Alternative A, 
because it contains the

[[Page 19085]]

same requirements as IESWTR, was expected to afford the same level of 
public health protection. Alternative B, (which removes the four-hour 
0.5 NTU trigger and the filter profile requirement) was expected to 
afford comparable health protection because the core components which 
provide the overwhelming majority of the public health protection 
(monitoring frequency, trigger which requires follow-up action, and the 
follow-up actions) are the same as the IESWTR. Alternative C was 
expected to provide comparable health protection because follow-up 
action is the same as under the IESWTR and a 0.5 NTU 95percent 
percentile trigger was expected to identify the same systems which the 
triggers established under the IESWTR would identify. All three were 
also considered useful diagnostic tools for small systems to evaluate 
the performance of filters and correct problems before follow-up action 
was necessary. The first alternative was viewed as significantly more 
challenging to implement and burdensome for smaller systems due to the 
amount of required daily data review. This evaluation was also echoed 
by small entity representatives during the Agency's SBREFA process as 
well as stakeholders at each of the public meetings held to discuss 
issues related to today's proposed rule. While Alternative C reduced 
burden associated with daily data review, it would institute a very 
different trigger for small systems than established by the IESWTR for 
large systems. This was viewed as problematic by several stakeholders 
who stressed the importance of maintaining similar requirements in 
order to limit transactional costs and additional State burden. 
Therefore, the Agency is proposing Alternative B as described above, 
which allows operators to expend less time to evaluate their turbidity 
data. Alternative B maintains a comparable level of public health 
protection as those afforded large systems, reduces much of the burden 
associated with daily data collection and review (removing the 
requirement to conduct a filter profile allows systems to review data 
once a week instead of daily if they so choose), yet still serves as a 
self-diagnostic tool for operators and provides the mechanism for State 
follow-up when significant performance problems exist.
iv. Request for Comments
    The individual filter monitoring provisions represent a challenging 
opportunity to provide systems with a useful tool for assessing filters 
and correcting problems before State intervention is necessary or 
combined filter turbidity is affected and treatment technique 
violations occur. The Agency is actively seeking comment on this 
provision. Because of the complexity of this provision, specific 
requests for comment have been broken down into five distinct areas.

Comments on the Alternatives

    EPA requests comment on today's proposed individual filter 
requirement and each of the alternatives as well as additional 
alternatives for this provision such as establishing a different 
frequency for individual filter monitoring (e.g., 60 minute or 30 
minute increments). The Agency also seeks comment or information on:
     Tools and or guidance which would be useful and necessary 
in order to educate operators on how to comply with individual filter 
provisions and perform any necessary calculations;
     Data correlating individual filter performance relative to 
combined filter effluent;
     Contributing factors to turbidity spikes associated with 
reduced filter performance;
     Practices which contribute to poor individual filter 
performance and filter spikes; and
     Any additional concerns with individual filter 
performance.

Modifications to the Alternatives

    The Agency also seeks comment on a variety of proposed 
modifications to the individual filter monitoring alternatives 
discussed which could be incorporated in order to better address the 
concerns and realities of small surface water systems. These 
modifications include:
     Modification of the alternatives to include a provision 
which would require systems which do not staff the plant during all 
hours of operation, to utilize an alarm/phone system to alert off-site 
operators of significantly elevated turbidity levels and poor 
individual filter performance;
     A modification to allow conventional and direct filtration 
systems with either 2-3 or less filters to sample combined filter 
effluent continuously (every 15 minutes) in lieu of monitoring 
individual filter turbidity. This modification would reduce the data 
collection/analysis burden for the smallest systems while not 
compromising the level of public health protection;
     A modification to lengthen the period of time (120 days or 
a period of time established by the State but not to exceed 120 days) 
for completion of the CPE and/or a modification to lengthen the 
requirement that a CPE must be conducted no later than 60 or 90 days 
following the exceedance; and
     A modification to require systems to notify the State 
within 24 hours of triggering the CPE or IFA. This would inform States 
sooner so they can begin to work with systems to address performance of 
filters and conduct CPEs and IFAs as necessary.

Establishment of Subcategories

    The Agency is also evaluating the need to establish subcategories 
in the final rule for individual filter monitoring/reporting. EPA is 
currently considering these three categories:
    1. Systems serving populations of 3,300 or more persons;
    2. Systems with more than 2 filters, but less than 3,300 persons; 
and
    3. Systems with 2 or fewer filters serving populations fewer than 
3,300 persons.
    Individual filter monitoring requirements would also be based on 
these subcategories. Systems serving 3,300 or greater would be required 
to meet the same individual turbidity requirements as the IESWTR 
(Alternative A as described above). Systems serving fewer than 3,300 
but using more than 2 filters would be required to meet a modified 
version of the IESWTR individual filter requirements (Alternative B as 
described above). Systems serving fewer than 3,300 and using 2 or fewer 
filters would continue to monitor and report only combined filter 
effluent turbidity at an increased frequency (once every 15 minutes, 30 
minutes, or one hour).
    Input and or comment on cut-offs for subcategories and how to apply 
subcategories to Alternatives is requested. The Agency would also like 
to take comment on additional strategies to tailor individual filter 
monitoring for the smallest systems while continuing to maintain an 
adequate level of public health protection. Such possible strategies 
include:
     Since small systems are often understaffed one approach 
would require those systems utilizing only two or fewer filters to 
utilize, maintain, and continually operate an alarm/phone system during 
all hours of operation, which alert off-site operators of significantly 
elevated turbidity levels and poor individual filter performance and/or 
automatically shuts the system down if turbidity levels exceed a 
specified performance level. This modification would be in addition to 
the proposed requirements.
     Establishing a more general modification which would 
require systems which do not staff the plant during all hours of 
operation to utilize

[[Page 19086]]

an alarm/phone system to alert off-site operators of significantly 
elevated turbidity levels and poor individual filter performance, and/
or to automatically shut the system down if turbidity levels exceed a 
specified performance level.
     If systems with 2 or fewer filters is allowed to sample 
combined filter effluent in lieu of individual filter effluent with a 
frequency of a reading every hour and combined filter effluent 
turbidity exceeds 0.5 NTU, should the system be required to take grab 
samples of individual filter turbidity for all filters every 15 minutes 
until the results of those samples are lower than 0.5 NTU?

Reliability

    Maintaining reliable performance at systems using filtration 
requires that the filters be examined at intervals to determine if 
problems are developing. This can mean that a filter must go off-line 
for replacement or upgrades of media, underdrains, backwash lines etc. 
In order to provide adequate public health protection at small systems, 
the lack of duplicate units can be a problem. EPA is considering 
requiring any system with only one filter to install an additional 
filter. The schedule would be set by the primacy agency, but the filter 
would have to be installed no later than 6 years after promulgation. 
EPA is requesting comment on this potential requirement.

Data Gathering Recordkeeping and Reporting

    The Agency is evaluating data gathering/reporting requirements for 
systems. A system collecting data at a frequency of once every 15 
minutes, (and operating) 24 hours a day, would record approximately 
2800 data points for each filter throughout the course of the month. 
Although the smallest systems in operation today routinely operate on 
the average of 4 to 12 hours a day (resulting in 480 to 1400 data 
points per filter), these systems do not typically use sophisticated 
data recording systems such as SCADAs. The lack of modern equipment at 
small systems may result in difficulty with retrieving and analyzing 
data for reporting purposes. While the Agency intends to issue guidance 
targeted at aiding these systems with the data gathering requirements, 
EPA is also seeking feedback on a modification to the frequency of data 
gathering required under each of the aforementioned options. 
Specifically, the Agency would like to request comment on modifying the 
frequency for systems serving fewer than 3,300 to continuous monitoring 
on a 30 or 60 minute basis. EPA also requests comment on the 
availability and practicality of data systems that would allow small 
systems, State inspectors, and technical assistance providers to use 
individual filter turbidity data to improve performance, perform filter 
analysis, conduct individual filter self assessments, etc. The Agency 
is interested in specific practical combinations of data recorders, 
charts, hand written recordings from turbidimeters, that would 
accomplish this.

Failure of Continuous Turbidity Monitoring

    Under today's proposed rule, the Agency requires that if there is a 
failure in the continuous turbidity monitoring equipment, the system 
must conduct grab sampling every four hours in lieu of continuous 
monitoring until the turbidimeter is back on-line. A system has five 
working days to resume continuous monitoring before a violation is 
incurred. EPA would like to solicit comment on modifying this component 
to require systems to take grab samples at an increased frequency, 
specifically every 30 minutes, 1 hour, or 2 hours.

B. Disinfection Benchmarking Requirements

    Small systems will be required to comply with the Stage 1 
Disinfection Byproduct Rule (Stage 1 DBPR) in the first calendar 
quarter of 2004. The Stage 1 DBPR set Maximum Contaminant Levels (MCLs) 
for Total Trihalomethanes (chloroform, bromodichloromethane, 
chlorodibromomethane, and bromoform), and five Haloacetic Acids (i.e., 
the sum of the concentrations of mono-, di-, and trichloroacetic acids 
and mono- and dibromoacetic acids.) The LT1FBR follows the principles 
set forth in earlier FACA negotiations, i.e., that existing microbial 
protection must not be significantly reduced or undercut as a result of 
systems taking the necessary steps to comply with the MCL's for TTHM 
and HAA5 set forth in Stage 1 DBPR. The disinfection benchmarking 
requirements are designed to ensure that risk from one contaminant is 
not increased while risk from another contaminant is decreased.
    The Stage 1 DBPR was promulgated because disinfectants such as 
chlorine can react with natural organic and inorganic matter in source 
water and distribution systems to form disinfection byproducts (DBPs). 
Results from toxicology studies have shown several DBPs (e.g., 
bromodichloromethane, bromoform, chloroform, dichloroacetic acid, and 
bromate) to potentially cause cancer in laboratory animals. Other DBPs 
(e.g., certain haloacetic acids) have been shown to cause adverse 
reproductive or developmental effects in laboratory animals. Concern 
about these health effects may cause public water utilities to consider 
altering their disinfection practices to minimize health risks to 
consumers.
    A fundamental principle, therefore, of the 1992-1993 regulatory 
negotiation reflected in the 1994 proposal for the IESWTR was that new 
standards for control of DBPs must not result in significant increases 
in microbial risk. This principle was also one of the underlying 
premises of the 1997 M-DBP Advisory Committee's deliberations, i.e., 
that existing microbial protection must not be significantly reduced or 
undercut as a result of systems taking the necessary steps to comply 
with the MCL's for TTHM and HAA5 set forth in Stage 1 DBPR. The 
Advisory Committee reached agreement on the use of microbial profiling 
and benchmarking as a process by which a PWS and the State, working 
together, could assure that there would be no significant reduction in 
microbial protection as the result of modifying disinfection practices 
in order to comply with Stage 1 DBPR.
    The process established under the IESWTR has three components: (1) 
Applicability Monitoring; (2) Disinfection Profiling; and (3) 
Disinfection Benchmarking. These components have the following three 
goals respectively: (1) determine which systems have annual average 
TTHM and HAA5 levels close enough to the MCL (e.g., 80 percent of the 
MCL) that they may need to consider altering their disinfection 
practices to comply with Stage 1 DBPR; (2) those systems that have TTHM 
and HAA5 levels of at least 80 percent of the MCLs must develop a 
baseline of current microbial inactivation over the period of 1 year; 
and (3) determine the benchmark, or the month with the lowest average 
level of microbial inactivation, which becomes the critical period for 
that year.
    The aforementioned components were applied to systems serving 
10,000 or more people in the IESWTR and were carried out sequentially. 
In response to concerns about early implementation (any requirement 
which would require action prior to 2 years after the promulgation date 
of the rule), the Agency is considering modifying the IESWTR approach 
for small systems, as described in the following section. Additionally, 
the specific provisions have been modified to take into account

[[Page 19087]]

specific needs of small systems. EPA's goal in developing these 
requirements is to recognize the specific needs of small system and 
States, while providing small systems with a useful means of ensuring 
that existing microbial protection must not be significantly reduced or 
undercut as a result of systems taking the necessary steps to comply 
with the MCL's for TTHM and HAA5 set forth in Stage 1 DBPR.
    The description of the disinfection benchmarking components of 
today's proposed rule will be broken into the three segments: (1) 
Applicability Monitoring; (2) Disinfection Profiling; and (3) 
Disinfection Benchmarking. Each section will provide an overview and 
purpose, data, a description of the proposed requirements, and request 
for comment.
1. Applicability Monitoring
a. Overview and Purpose
    The purpose of the TTHM and HAA5 applicability monitoring is to 
serve as an indicator for systems that are likely to consider making 
changes to their disinfection practices in order to comply with the 
Stage 1 DBPR. TTHM samples which equal or exceed 0.064 mg/L and/or HAA5 
samples equal or exceed 0.048 mg/L (80 percent of their respective 
MCLs) represent DBP levels of concern. Systems with TTHM or HAA5 levels 
exceeding 80 percent of the respective MCLs may consider changing their 
disinfection practice in order to comply with the Stage 1 DBPR.
b. Data
    In 1987, EPA established monitoring requirements for 51 unregulated 
synthetic organic chemicals. Subsequently, an additional 113 
unregulated contaminants were added to the monitoring requirements. 
Information on TTHMs has become available from the first round of 
monitoring conducted by systems serving fewer than 10,000 people.
    Preliminary analysis of the data from the Unregulated Contaminant 
Information System (URCIS, Data) suggest that roughly 12 percent of 
systems serving fewer than 10,000 would exceed 64 /L or 80 
percent of the MCL for TTHM (Table IV.7). This number is presented only 
as an indicator, as it represents samples taken at the entrance to 
distribution systems. In general, TTHMs and HAA5s tend to increase with 
time as water travels through the distribution system. The Stage 1 
Disinfection Byproducts Rule estimated 20 percent of systems serving 
fewer than 10,000 would exceed 80 percent of the MCLs for either TTHMs 
or HAA5s or both. EPA is working to improve the knowledge of TTHM and 
HAA5 formation kinetics in the distribution systems for systems serving 
fewer than 10,000 people. EPA is currently developing a model to 
predict the formation of TTHM and HAA5 in the distribution system based 
on operational measurements. This model is not yet available. In order 
to develop a better estimate of the percent of small systems that would 
be triggered into the profiling requirements (i.e., develop a profile 
of microbial inactivation over a period of 1 year) EPA is considering 
the following method:
     Use URCIS data to show how many systems serving 10,000 or 
more people have TTHM levels at or above 0.064 mg/L;
     Compare those values to the data received from the 
Information Collection Rule for TTHM average values taken at 
representative points in the distribution system;
     Determine the mathematical factor by which the two values 
differ; and
     Apply that factor to the URCIS data for systems serving 
fewer than 10,000 people to estimate the percent of those systems that 
would have TTHM values at or above 0.064mg/L as an average of values 
taken at representative points in the distribution system.

            Table IV.7.--TTHM Levels at Small Surface Systems
        [Data from Unregulated Contaminant Database, 1987-92 \1\]
------------------------------------------------------------------------
                                                Number of
                                                systems w/
                                                ave. TTHM      Maximum
                                     Total         level of
 System size (population served)   number of    64 g/L  (80  (g/
                                                % of MCL)        L)
 
------------------------------------------------------------------------
500.............................           74       0 (0%)            56
501-1,000.......................           44    6 (13.6%)           222
1,001-3,300.....................          114   12 (10.5%)           172
3,301-10,000....................          116   25 (21.6%)           279
                                 ---------------------------------------
    Total.......................          348   43 (12.4%)          279
------------------------------------------------------------------------
\1\ In Unregulated Contaminant Database (1987-1992), there are ten
  States (i.e., CA, DE, IN, MD, MI, MO, NC, NY, PR, WV). However, only
  eight of them can be identified with the data of both population and
  TTHM for systems serving fewer than 10,000 people (See next page).

    The Agency requests comment on this approach to estimating TTHM 
levels in the distribution system based on TTHM levels at the entry 
point to the distribution system. The Agency also requests comment on 
the relationship of HAA5 formation relative to TTHM formation in the 
distribution system. Specifically, is there data to support the 
hypothesis that HAA5s do not peak at the same point in the distribution 
system as TTHMs?
    The Agency also received two full years of TTHM data for seventy-
four systems in the State of Missouri (Missouri, 1998). This data 
consisted of quarterly TTHM data, which was converted into an annual 
average. The data (presented in Table IV.8) demonstrates a very 
different picture than that displayed by the URCIS data described 
above. In 1996, 88 percent of the systems exceeded 64 g/L, 
while in 1997, 85 percent exceeded 64 g/L. Figure IV.7 
graphically displays this data set.

[[Page 19088]]



    Table IV.8.--TTHM Levels at Small Surface Systems in the State of
                                Missouri
                     [State of Missouri, 1996, 1997]
------------------------------------------------------------------------
                                                Number of
                                                systems w/
                                                ave. TTHM      Maximum
                                     Total         Level of
              Year                 number of    64 g/L (80   (g/
                                                percent of       L)
                                                   MCL)
 
------------------------------------------------------------------------
1996............................           74     65 (88%)           276
1997............................           75     64 (85%)           251
All years.......................          149    129 (87%)           276
------------------------------------------------------------------------

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    There are several potential reasons for the differences between the 
data shown in Tables IV.7 and IV.8. Data in Table IV.7 contains zero 
values which may be indicative of no sample being taken rather than a 
sample with a value of zero. Additionally, data shown in IV.8 was 
collected within the distribution system, while data in Table IV.7 was 
taken at the entry point to the distribution system. The data 
collection method used in collecting the data

[[Page 19090]]

shown in Table IV.8 is similar to the methodology required under the 
Stage 1 DBPR.
c. Proposed Requirements
    EPA considered four alternatives for systems to use TTHM and HAA5 
data to determine which systems whether they would be required to 
develop a disinfection profile. In today's proposed rule, EPA is 
proposing Alternative 4.

Alternative 1

    The IESWTR required that systems monitor for TTHMs at four points 
in the distribution system each quarter. At least one of those samples 
must be taken at a point which represents the maximum residence time of 
the water in the system. The remaining three must be taken at 
representative locations in the distribution system, taking into 
account number of persons served, different sources of water and 
different treatment methods employed. The results of all analyses per 
quarter are averaged and reported to the State.
    EPA considered applying this alternative to systems serving fewer 
than 10,000 people and requested input from small system operators and 
other interested parties, including the public. Based on the feedback 
EPA received, two other alternatives were developed for consideration 
(listed as Alternatives 2 and 3).

Alternative 2

    EPA considered requiring systems serving fewer than 10,000 people 
to monitor for TTHM and HAA5 at the point of maximum residence time 
according to the following schedule:
     No less than once per quarter per treatment plant operated 
for systems serving populations between 500 and 10,000 persons; and no 
less than once per year per treatment plant during the month of warmest 
water temperature for systems serving populations less than 500. If 
systems wish to take additional samples, however, they would be 
permitted to do so.
     Systems may consult with States and elect not to perform 
TTHM and HAA5 monitoring and proceed directly with the development of a 
disinfection profile.
    This alternative provides an applicability monitoring frequency 
identical to the DBP monitoring frequency under the Stage 1 DBPR that 
systems will have to comply with in 2004. In addition, it allows 
systems the flexibility to skip TTHM and HAA5 monitoring completely, 
pending State approval, and begin profiling immediately.

Alternative 3

    EPA considered requiring all systems serving fewer than 10,000 
people to monitor once per year per system during the month of warmest 
water temperature of 2002 and at the point of maximum residence time.
    During the SBREFA process and during stakeholder meetings, EPA 
received some positive comments regarding Alternative 3 as the least 
burdensome approach. Other stakeholders, however, pointed out that 
Alternative 3 does not allow systems to measure seasonal variation as 
is done in Alternative 2 for systems serving populations between 500 
and 10,000. Several stakeholders agreed that despite the costs, the 
information obtained from applicability monitoring will be useful. EPA 
agrees that it is valuable to systems to monitor and understand the 
seasonal variation in TTHM and HAA5 values, however, EPA has determined 
that requiring a full year of monitoring may place an excessive burden 
on both States and systems. In order to complete a full year of 
monitoring and another full year of disinfection data gathering, 
systems would have to start TTHM and HAA5 monitoring January of 2002.
    Under SDWA, States have two years to develop their own regulations 
as part of their primacy requirements, EPA recognized that requiring 
Applicability Monitoring during this period would pose a burden on 
States. In response to these concerns, the Agency developed a new 
alternative, described in the following paragraph.

Alternative 4

    Applicability Monitoring is optional and not a requirement under 
today's proposed rule. If a system has TTHM and HAA5 data taken during 
the month of warmest water temperature (from 1998-2002) and taken at 
the point of maximum residence time, they may submit this data to the 
State prior to [DATE 2 YEARS AFTER PUBLICATION OF FINAL RULE]. If the 
data shows TTHM and HAA5 levels less than 80 percent of the MCLs, the 
system does not have to develop a disinfection profile. If the data 
shows TTHM and HAA5 levels at or above 80 percent of the MCLs, the 
system would be required to develop a disinfection profile in 2003 as 
described later in section IV.B.2. If the system does not have, or does 
not gather TTHM and HAA5 data during the month of warmest water 
temperature and at the point of maximum residence time in the 
distribution system as described, then the system would automatically 
be required to develop a disinfection profile starting January 1 of 
2003. This option still provides systems with the necessary tools for 
assessing potential changes to their disinfection practice, (i.e. the 
generation of the profile), while not forcing States to pass their 
primacy regulations, contact all small systems within their 
jurisdiction, and set up TTHM and HAA5 monitoring all within the first 
year after promulgation of this rule. Systems will still be able to 
ensure public health protection by having the disinfection profile when 
monitoring under Stage 1 DBPR takes effect. It should be noted that EPA 
estimates the cost for applicability monitoring (as described in 
Alternative 4) and disinfection profiling (as described in Alternative 
3 in Section IV.B.2.c of this preamble) are roughly equivalent. EPA 
anticipates that systems with known low levels of TOC may opt to 
conduct the applicability monitoring while the remaining systems will 
develop a disinfection profile.
d. Request for Comment
    EPA requests comment on the proposed requirement, other 
alternatives listed, or other alternatives that have not yet been 
raised for consideration. The Agency also requests comment on 
approaches for determining the percent of systems that would be 
affected by this requirement. Specifically:
     With respect to Alternative 4, the Agency requests comment 
on approaches for determining the percent of systems that might 
demonstrate TTHM and HAA5 levels less than 80 percent of their 
respective MCLs and would therefore not develop a disinfection profile.
     The Agency requests additional information (similar to the 
State of Missouri data discussed previously) on the current levels of 
TTHM and HAA5s in the distribution systems of systems serving fewer 
than 10,000 people.
     The Agency requests comment on developing a TTHM and HAA5 
monitoring scheme during the winter months as opposed to the current 
monitoring scheme based on the highest TTHM/HAA5 formation potential 
during the month of warmest water temperature. If a relationship can be 
established, and shown to be consistent through geographical 
variations, EPA would consider modifying an alternative so that 
applicability monitoring would occur during the 1st quarter of 2003.
     The Agency requests comment on modifying Alternative 3, to 
require systems to begin monitor for TTHMs and HAA5s during the warmest 
water temperature month of 2003. The results of this monitoring would 
be used to

[[Page 19091]]

determine whether a system would need to develop a disinfection profile 
during 2004. This option is closer in structure and timing to the 
IESWTR and has been included for comment. It should be noted, however, 
that postponing the disinfection profile until 2004 would prevent 
systems from having inactivation data prior to their compliance date 
with the Stage 1 DBPR, possibly compromising simultaneous compliance.
2. Disinfection Profiling
a. Overview and Purpose
    The disinfection profile is a graphical representation showing how 
disinfection varies at a given plant over time. The profile gives the 
plant operator an idea of how seasonal changes in water quality and 
water demand can have a direct effect on the level of disinfection the 
plant is achieving.
    The strategy of disinfection profiling and benchmarking stemmed 
from data provided to the EPA and M-DBP Advisory Committee by PWSs and 
reviewed by stakeholders. The microbial inactivation data (expressed as 
logs of Giardia lamblia inactivation) used by the M-DBP Advisory 
Committee demonstrated high variability. Inactivation varied by several 
log on a day-to-day basis at any particular treatment plant and by as 
much as tens of logs over a year due to changes in water temperature, 
flow rate (and, consequently, contact time), seasonal changes in 
residual disinfectant, pH, and disinfectant demand and, consequently, 
disinfectant residual. There were also differences between years at 
individual plants. To address these variations, M-DBP stakeholders 
developed the procedure of profiling inactivation levels at an 
individual plant over a period of at least one year, and then 
establishing a benchmark of minimum inactivation as a way to 
characterize disinfection practice. This approach makes it possible for 
a plant that may need to change its disinfection practice in order to 
meet DBP MCLs to determine the impact the change would have on its 
current level of disinfection or inactivation and, thereby, to assure 
that there is no significant increase in microbial risk. In order to 
develop the profile, a system must measure four parameters (EPA is 
assuming most small systems use chlorine as their disinfection agent, 
and these requirements are based on this assumption):
    (1) Disinfectant residual concentration (C, in mg/L) before or at 
the first customer and just prior to each additional point of 
disinfectant addition;
    (2) Contact time (T, in minutes) during peak flow conditions;
    (3) Water temperature ( deg.C); and
    (4) pH.
    Systems convert this operational data to a number representing log 
inactivation values for Giardia by using tables provided by EPA. 
Systems graph this information over time to develop a profile of their 
microbial inactivation. EPA will prepare guidance specifically 
developed for small systems to assist in the development of the 
disinfection profile. Several spreadsheets and simple programs are 
currently available to aid in calculating microbial inactivation and 
the Agency intends to make such spreadsheets available in guidance.
b. Data
    Figure IV.8a depicts a hypothetical disinfection profile showing 
seasonal variation in microbial inactivation.
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[[Page 19093]]


c. Proposed Requirements
    EPA considered four alternatives for requiring systems to develop 
the disinfection profile.

Alternative 1

    The IESWTR requires systems serving 10,000 or more persons to 
measure the four parameters described above and develop a profile of 
microbial inactivation on a daily basis. EPA considered extending this 
requirement to systems serving fewer than 10,000 persons and requested 
input from small system operators and other interested stakeholders 
including the public. EPA received feedback that this requirement would 
place too heavy of a burden on the small system operator for at least 
two reasons:
     Small system operators are not present at the plant every 
day; and
     Small systems often have only one operator at a plant who 
is responsible for all aspects of maintenance, monitoring and 
operation.

Alternative 2

    EPA also considered not requiring the disinfection profile at all. 
After consideration of the feedback of small system operators and other 
interested stakeholders, however, EPA believes that there is a strong 
benefit in the plant operator knowing the level of microbial 
inactivation, and that the principles developed during the regulation 
negotiation and Federal Advisory Committee prior to promulgation of the 
IESWTR could be applied to small systems for the purpose of public 
health protection. Recognizing the potential burdens the profiling 
procedures placed on small systems, EPA considered two additional 
alternatives.

Alternative 3

    EPA considered requiring all systems serving fewer than 10,000 
persons, to develop a disinfection profile based on weekly measurements 
for one year during or prior to 2003. A system with TTHM and HAA5 
levels less than 80 percent of the MCLs (based on either required or 
optional monitoring as described in section IV.B.1) would not be 
required to conduct disinfection profiling. EPA believes this 
alternative would save the operator time (in comparison to Alternative 
1), and still provide information on seasonal variation over the period 
of one year.

Alternative 4

    Finally, EPA considered a monitoring requirement only during a one 
month critical monitoring period to be determined by the State. In 
general, colder temperatures reduce disinfection efficiency. For 
systems in warmer climates, or climates that do not change very much 
during the course of the year, the State would identify other critical 
periods or conditions. This alternative reduces the number of times the 
operator has to calculate the microbial inactivation.
    EPA considered all of the above alternatives, and in today's 
proposed rule, EPA is proposing Alternative 3. First, this alternative 
does not require systems to begin monitoring before States have two 
years to develop their regulations as part of primacy requirements. 
Given early implementation concerns, the timing of this alternative 
appears to be the most appropriate in balancing early implementation 
issues with the need for systems to prepare for implementation of the 
Stage 1 DBPR and ensuring adequate and effective microbial protection. 
Second, it allows systems and States which have been proactive in 
conducting applicability monitoring to reduce costs for those systems 
which can demonstrate low TTHM and HAA5 levels. Third, this alternative 
allows systems and States the opportunity to understand seasonal 
variability in microbial disinfection. Finally, this alternative takes 
into account the flexibility needed by the smallest systems while 
maintaining comparable levels of public health protection with the 
larger systems.
Request for Comments
    EPA requests comment on this proposed requirement as well as 
Alternatives 1,2, and 4. The Agency also requests comment on a possible 
modification to Alternatives 1, 3 and 4. Under this modification, 
systems serving populations fewer than 500 would have the opportunity 
to apply to the State to perform the weekly inactivation calculation 
(although data weekly data collection would still be required). If the 
system decided to make a change in disinfection practice, then the 
State would assist the system with the development of the disinfection 
profile.
    The Agency also requests comment on a modification to Alternative 3 
which would require systems to develop a disinfection profile in 2004 
only if Applicability Monitoring conducted in 2003 indicated TTHM and 
HAA5 levels of 80 percent or greater of the MCL. This modification 
would be coupled with the applicability monitoring modification 
discussed in the previous section.
3. Disinfection Benchmarking
a. Overview and Purpose
    The DBPR requires systems to meet lower MCLs for a number of 
disinfection byproducts. In order to meet these requirements, many 
systems will require changes to their current disinfection practices. 
In order to ensure that current microbial inactivation does not fall 
below those levels required for adequate Giardia and virus inactivation 
as required by the SWTR, a disinfection benchmark is necessary. A 
disinfection benchmark represents the lowest average monthly Giardia 
inactivation level achieved by a system. Using this benchmark States 
and systems can begin to understand the current inactivation achieved 
at the system, and estimate how changes to disinfection practices will 
affect inactivation.
b. Data
    Based on the hypothetical disinfection profile depicted in Figure 
IV.8a, the benchmark, or critical period, is the lowest level of 
inactivation achieved by the system over the course of the year. Figure 
IV.8b shows that this benchmark (denoted by the dotted line) takes 
place in December for the hypothetical system.
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c. Proposed Requirements
    If a system that is required to produce a disinfection profile 
decides to make a significant change in disinfection practice after the 
profile is developed, it must consult with the State and receive 
approval before implementing such a change. Significant changes in 
disinfection practice are defined as: (1) moving the point of 
disinfection (other than 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. Supporting materials for such consultation 
with the State must include a description of the proposed change, the 
disinfection profile developed under today's proposed rule for Giardia 
lamblia (and, if necessary, viruses for systems using ozone or 
chloramines), and an analysis of how the proposed change might affect 
the current level of Giardia inactivation. In addition, the State is 
required to review disinfection profiles as part of its periodic 
sanitary survey.
    A log inactivation benchmark is calculated as follows:
    (1) Calculate the average log inactivation for either each calendar 
month, or critical monitoring period (depending on final rule 
requirement for the profiling provisions).
    (2) Determine the calendar month with the lowest average log 
inactivation; or lowest inactivation level within the critical 
monitoring period.
    (3) The lowest average month, or lowest level during the critical 
monitoring period becomes the critical measurement for that year.
    (4) If acceptable data from multiple years are available, the 
average of critical periods for each year becomes the benchmark.
    (5) If only one year of data is available, the critical period 
(lowest monthly average inactivation level) for that year is the 
benchmark.
d. Request for Comments
    EPA has included a requirement that State approval be obtained 
prior to making a significant change to disinfection practice. EPA 
requests comment on whether the rule should require State approval or 
whether only state consultation is necessary.
    EPA also requests comment on providing systems serving fewer than 
500 the option to provide raw data to the State, and allowing the State 
to determine the benchmark.

C. Additional Requirements

1. Inclusion of Cryptosporidium in definition of GWUDI
a. Overview and Purpose
    Groundwater sources are found to be under the direct influence of 
surface water (GWUDI) if they exhibit specific traits. The SWTR defined 
ground waters containing Giardia lamblia as GWUDI. One such trait is 
the presence of protozoa such as Giardia which migrate from surface 
water to groundwater. The IESWTR expanded the SWTR's definition of 
GWUDI to include the presence of Cryptosporidium. The Agency believes 
it appropriate and necessary to extend this modification of the 
definition of GWUDI to systems serving fewer than 10,000 persons.
b. Data
    The Agency issued guidance on the Microscopic Particulate Analysis 
(MPA) in October 1992 as the Consensus Method for Determining 
Groundwater Under the Direct Influence of Surface Water Using 
Microscopic Particulate Analysis (EPA, 1992). Additional guidance for 
making GWUDI determinations is also available (USEPA, 1994a,b). Since 
1990, States have acquired substantial experience in making GWUDI 
determinations and have documented their approaches (Massachusetts 
Department of Environmental Protection, 1993; Maryland, 1993; Sonoma 
County Water Agency, 1991). Guidance on existing practices undertaken 
by States in response to the SWTR may also be found in the State 
Sanitary Survey Resource Directory, jointly published in December 1995 
by EPA and the Association of State Drinking Water Administrators (EPA/
ASDWA). AWWARF has also published guidance (Wilson et al., 1996).
    Most recently, Hancock et al. (1997) used the MPA test to study the 
occurrence of Giardia and Cryptosporidium in the subsurface. They found 
that, in a study of 383 ground water samples, the presence of Giardia 
correlated with the presence of Cryptosporidium. The presence of both 
pathogens correlated with the amount of sample examined, but not with 
the month of sampling. There was a correlation between source depth and 
occurrence of Giardia but not Cryptosporidium. The investigators also 
found no correlation between the distance of the ground water source 
from adjacent surface water and the occurrence of either Giardia or 
Cryptosporidium. However, they did find a correlation between distance 
from a surface water source and generalized MPA risk ratings of high 
(high represents an MPA score of 20 or greater), medium or low, but no 
correlation was found with the specific numerical values that are 
calculated by the MPA scoring system. An additional two reports (SAIC 
1997a and 1997b) provide data on wells with Giardia cyst and 
Cryptosporidium oocyst recovery and concurrent MPA analysis.
c. Proposed Requirements
    In today's proposed rule, EPA is modifying the definition of GWUDI 
to include Cryptosporidium for systems serving fewer than 10,000 
persons.
    Under the SWTR, States were required to determine whether systems 
using ground water were using ground water under the direct influence 
of surface water (GWUDI). State determinations were required to be 
completed by June 29, 1994 for CWSs and by June 29, 1999 for NCWSs. EPA 
does not believe that it is necessary to make a new determination of 
GWUDI for this rule based on the addition of Cryptosporidium to the 
definition of ``ground water under the direct influence of surface 
water''. While a new determination is not required, States may elect to 
conduct a new analysis based on such factors as a new land use pattern 
(conversion to dairy farming, addition of septic tanks).
    EPA does not believe that a new determination is necessary because 
the current screening methods appear to adequately address the 
possibility of Cryptosporidium in the ground water.
d. Request for Comments
    The Agency requests comment on the proposal to modify the 
definition of GWUDI to include Cryptosporidium for systems serving 
fewer than 10,000 persons.
2. Inclusion of Cryptosporidium Watershed Requirements for Unfiltered 
Systems
a. Overview and Purpose
    Existing SWTR requirements for unfiltered surface water and GWUDI 
systems require these systems to minimize the potential for source 
water contamination by Giardia lamblia and viruses. Because 
Cryptosporidium has proven resistant to levels of disinfection 
currently practiced at systems throughout the country, the Agency felt 
it imperative to include Cryptosporidium in the watershed control 
provisions wherever Giardia lamblia is mentioned. The IESWTR therefore, 
modified existing watershed regulatory requirements for unfiltered 
systems to include the control of

[[Page 19096]]

Cryptosporidium. The Agency believes it appropriate and necessary to 
extend this requirement to systems serving fewer than 10,000 persons.
    It should be noted that today's proposed requirements do not 
replace requirements established for unfiltered systems under the SWTR. 
Systems must continue to maintain compliance with the requirements of 
the SWTR for avoidance of filtration. If an unfiltered system fails any 
of the avoidance criteria, that system must install filtration within 
18 months, regardless of future compliance with avoidance criteria.
    EPA anticipates that in the planned Long Term 2 Enhanced Surface 
Water Treatment rule, the Agency will reevaluate treatment requirements 
necessary to manage risks posed by Cryptosporidium and other microbial 
pathogens in both filtered and unfiltered surface water systems. In 
conducting this reevaluation, EPA will utilize the results of several 
large surveys, including the Information Collection Rule (ICR) and ICR 
Supplemental Surveys, to more fully characterize the occurrence of 
waterborne pathogens, as well as watershed and water quality parameters 
which might serve as indicators of pathogen risk level. The LT2ESWTR 
will also incorporate the results of ongoing research on removal and 
inactivation efficiencies of treatment processes, as well as studies of 
pathogen health effects and disease transmission. Promulgation of the 
LT2ESWTR is currently scheduled for May, 2002.
b. Data
    Watershed control requirements were initially established in 1989 
(54 FR 27496, June 29, 1989) (EPA, 1989b), as one of a number of 
preconditions that a public water system using surface water must meet 
to avoid filtration. The SWTR specifies the conditions under which a 
system can avoid filtration (40 CFR 141.71). These conditions include 
good source water quality, as measured by concentrations of coliforms 
and turbidity; disinfection requirements; watershed control; periodic 
on-site inspections; the absence of waterborne disease outbreaks; and 
compliance with the Total Coliform Rule and the MCL for TTHMs. The 
watershed control program under the SWTR must include a 
characterization of the watershed hydrology characteristics, land 
ownership, and activities which may have an adverse effect on source 
water quality, and must minimize the potential for source water 
contamination by Giardia lamblia and viruses.
    The SWTR Guidance Manual (EPA, 1991a) identifies both natural and 
human-caused sources of contamination to be controlled. These sources 
include wild animal populations, wastewater treatment plants, grazing 
animals, feedlots, and recreational activities. The SWTR Guidance 
Manual recommends that grazing and sewage discharges not be permitted 
within the watershed of unfiltered systems, but indicates that these 
activities may be permissible on a case-by-case basis where there is a 
long detention time and a high degree of dilution between the point of 
activity and the water intake. Although there are no specific 
monitoring requirements in the watershed protection program, the non-
filtering utility is required to develop State-approved techniques to 
eliminate or minimize the impact of identified point and non-point 
sources of pathogenic contamination. The guidance already suggests 
identifying sources of microbial contamination, other than Giardia, 
transmitted by animals, and points out specifically that 
Cryptosporidium may be present if there is grazing in the watershed.
c. Proposed Requirements
    In today's proposed rule, EPA is extending the existing watershed 
control regulatory requirements for unfiltered systems serving fewer 
than 10,000 people to include the control of Cryptosporidium. 
Cryptosporidium will be included in the watershed control provisions 
for these systems wherever Giardia lamblia is mentioned.
    Specifically, the public water system must maintain a watershed 
control program which minimizes the potential for contamination by 
Giardia lamblia, and Cryptosporidium oocysts and viruses in the water. 
The State must determine whether the watershed control program is 
adequate to meet this goal. The adequacy of a program to limit 
potential contamination by Giardia lamblia cysts, Cryptosporidium 
oocysts and viruses must be based on: The comprehensiveness of the 
watershed review; the effectiveness of the system's program to monitor 
and control detrimental activities occurring in the watershed; and the 
extent to which the water system has maximized land ownership and/or 
controlled land use within the watershed.
    It should be noted that unfiltered systems must continue to 
maintain compliance with the requirements of the SWTR for avoidance of 
filtration. If an unfiltered system fails any of the avoidance 
criteria, that system must install filtration within 18 months, 
regardless of future compliance with avoidance criteria.
d. Request for Comments
    EPA requests comment on the inclusion of these requirements for 
unfiltered systems serving fewer than 10,000 people.
3. Requirements for Covering New Reservoirs
a. Overview and Purpose
    Open finished water reservoirs, holding tanks, and storage tanks 
are utilized by public water systems throughout the country. Because 
these reservoirs are open to the environment and outside influences, 
they can be subject to the reintroduction of contaminants which the 
treatment plant was designed to remove. The IESWTR contains a 
requirement that all newly constructed finished water reservoirs, 
holding tanks, and storage tanks be covered. The Agency believes it 
appropriate and necessary to extend this requirement to systems serving 
fewer than 10,000 people.
b. Data
    Existing EPA guidelines recommend that all finished water 
reservoirs and storage tanks be covered (EPA, 1991b). The American 
Water Works Association (AWWA) also has issued a policy statement 
strongly supporting the covering of reservoirs that store potable water 
(AWWA, 1993). In addition, a survey of nine States was conducted in the 
summer of 1996 (Montgomery Watson, 1996). The States which were 
surveyed included several in the West (Oregon, Washington, California, 
Idaho, Arizona, and Utah), two States in the East known to have water 
systems with open reservoirs (New York and New Jersey), and one 
midwestern State (Wisconsin). Seven of the nine States which were 
surveyed require by direct rule that all new finished water reservoirs 
and tanks be covered.
    Under the IESWTR, systems serving populations of 10,000 or greater 
were prohibited from constructing uncovered finished water reservoirs 
after February 16, 1999. The Agency developed an Uncovered Finished 
Water Reservoirs Guidance Manual (USEPA, 1999f) which provides a basic 
understanding of the potential sources of external contamination in 
uncovered finished water reservoirs. It also provides guidance to water 
treatment operators for evaluating and maintaining water quality in 
reservoirs. The document discusses:
     Existing regulations and policies pertaining to uncovered 
reservoirs;
     Development of a reservoir management plan;

[[Page 19097]]

     Potential sources of water quality degradation and 
contamination;
     Operation and maintenance of reservoirs to maintain water 
quality; and
     Mitigating potential water quality degradation.
    As discussed in the 1997 IESWTR NODA (EPA, 1997b), when a finished 
water reservoir is open to the atmosphere it may be subject to some of 
the environmental factors that surface water is subject to, depending 
upon site-specific characteristics and the extent of protection 
provided. Potential sources of contamination to uncovered reservoirs 
and tanks include airborne chemicals, surface water runoff, animal 
carcasses, animal or bird droppings and growth of algae and other 
aquatic organisms due to sunlight that results in biomass (Bailey and 
Lippy, 1978). In addition, uncovered reservoirs may be subject to 
contamination by persons tossing items into the reservoir or illegal 
swimming (Pluntze 1974; Erb, 1989). Increases in algal cells, 
heterotrophic plate count (HPC) bacteria, turbidity, color, particle 
counts, biomass and decreases in chlorine residuals have been reported 
(Pluntze, 1974, AWWA Committee Report, 1983, Silverman et al., 1983, 
LeChevallier et al. 1997a).
    Small mammals, birds, fish, and the growth of algae may contribute 
to the microbial degradation of an open finished water reservoir 
(Graczyk et al., 1996a; Geldreich, 1990; Fayer and Ungar, 1986;). In 
one study, sea gulls contaminated a 10 million gallon reservoir and 
increased bacteriological growth, and in another study waterfowl were 
found to elevate coliform levels in small recreational lakes by twenty 
times their normal levels (Morra, 1979). Algal growth increases the 
biomass in the reservoir, which reduces dissolved oxygen and thereby 
increases the release of iron, manganese, and nutrients from the 
sediments. This, in turn, supports more growth (Cooke and Carlson, 
1989). In addition, algae can cause drinking water taste and odor 
problems as well as impact water treatment processes. A 1997 study 
conducted by the City of Seattle (Seattle Public Utilities, 1997) 
evaluated nutrient loadings by three groups of birds at Seattle's open 
reservoirs. Table IV.9 indicated the amount of soluble nutrient 
loadings estimated over the course of the year. It shows that bird 
feces may contribute nutrient loadings that can enhance algal growth in 
the reservoir.

                                     Table IV.9.--1997 Nutrient Loadings by Bird Groups in Seattle's Open Reservoirs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                          Geese                 Gulls                 Ducks                Overall
                                                                 ---------------------------------------------------------------------------------------
                            Reservoir                             Nitr. kg/  Phos. kg/  Nitr. kg/  Phos. kg/  Nitr. kg/  Phos. kg/  Total kg/  Conc. (mg/
                                                                      yr         yr         yr         yr         yr         yr         yr         L)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Beacon Hill*....................................................       0.00       0.00       0.00       0.00       0.00       0.00       0.00       0.00
Bitter Lake.....................................................       0.82       0.24       0.01       0.00       0.06       0.02       1.15      14.09
Green Lake......................................................       1.78       0.52       0.03       0.01       0.53       0.16       3.04      16.05
Lake Forest.....................................................       2.23       0.65       0.36       0.11       0.07       0.02       3.43      15.09
Lincoln.........................................................       0.00       0.00       0.24       0.07       0.01       0.00       0.31       3.96
Maple Leaf......................................................       2.16       0.63       0.13       0.04       0.35       0.10       3.42      15.43
Myrtle..........................................................       0.00       0.00       0.08       0.02       0.01       0.00       0.12       4.35
Volunteer.......................................................       0.00       0.00       0.01       0.00       0.01       0.00       0.03       0.42
West Seattle....................................................       0.40       0.12       0.38       0.11       0.02       0.01       1.03          4
--------------------------------------------------------------------------------------------------------------------------------------------------------

c. Proposed Requirements
    In today's proposed rule EPA is requiring surface water and GWUDI 
systems that serve fewer than 10,000 people to cover all new 
reservoirs, holding tanks or other storage facilities for finished 
water for which construction begins 60 days after the publication of 
the final rule in the Federal Register. Today's proposed rule does not 
apply these requirements to existing uncovered finished water 
reservoirs.
d. Request for Comments
    EPA solicits comments regarding the requirement to require that all 
new reservoirs, holding tanks and storage facilities for finished water 
be covered.

D. Recycle Provisions for Public Water Systems Employing Rapid Granular 
Filtration Using Surface Water and GWUDI as a Source

    Section 1412(b)(14) of the 1996 SDWA Amendments requires EPA to 
promulgate a regulation to govern the recycle of filter backwash within 
the treatment process of public water systems. The Agency is concerned 
that the recycle of spent filter backwash and other recycle streams may 
introduce additional Cryptosporidium oocysts to the treatment process. 
Adding oocysts to the treatment process may increase the risk oocysts 
will occur in finished water supplies and threaten public health. The 
Agency is further concerned because Cryptosporidium is not inactivated 
by standard disinfection practice, an important treatment barrier 
employed to control microbial pathogens. Oocysts returned to the plant 
by recycle flow therefore remain a threat to pass through filters into 
the finished water.
    The Agency engaged in three primary information gathering 
activities to investigate the potential risk posed by returning recycle 
flows that may contain Cryptosporidium to the treatment process. First, 
the Agency performed a broad literature search to gather research 
papers and information on the occurrence of Cryptosporidium and organic 
and inorganic materials in recycle flows. The literature search also 
sought information regarding the potential impact recycle may have on 
plant treatment efficiency. Second, the Agency worked with AWWA, 
AWWSCo., and Cincinnati Water Works to develop twelve issue papers on 
commonly generated recycle flows (Environmental Engineering and 
Technology, Inc.,1999). These papers are summarized in the next 
section. Information from EPA's literature search was incorporated into 
the issue papers. Third, the Agency presented preliminary data and 
potential regulatory components to stakeholders, and solicited 
feedback, at public meetings in Denver, Colorado, and Dallas, Texas. 
EPA also received valuable input from representatives of small water 
systems through the SBREFA process.
    Through the above activities, the Agency has identified four 
primary concerns regarding the recycle of spent filter backwash and 
other recycle streams within the treatment process of PWSs. The first 
concern is that some recycle flows contain Cryptosporidium oocysts, 
frequently at higher concentrations than plant source waters. Recycling 
these flows may increase the number of oocysts entering the plant and 
the number of oocysts reaching the filters. Loading more oocysts to the

[[Page 19098]]

filters could increase finished water oocyst concentrations. The second 
concern regards the location in the treatment process recycle flow is 
returned. The return of recycle at the point of primary coagulant 
addition or downstream of it may disrupt treatment chemistry by 
introducing residual coagulant or other treatment chemicals to the 
process stream and thereby lower plant treatment efficiency. Also, 
recycle flow returned to the clarification process may not achieve 
sufficient residence time for oocysts in the recycle flow to be 
removed, or it may create hydraulic currents that lower the unit's 
overall oocyst removal efficiency. The third concern regards direct 
filtration plants. Direct filtration plants do not employ clarification 
in their primary treatment process to remove suspended solids and 
oocysts; all oocyst removal is achieved by the filters. If the recycle 
flow is not treated before being returned to the plant, all of the 
oocysts captured by a filter during a filter run will be returned to 
the plant and again loaded to the filters. This may lead to ever 
increasing levels of oocysts being applied to the filters and could 
increase the concentration of oocysts in finished water. Therefore, it 
is important for direct filtration plants to provide adequate recycle 
flow treatment to remove oocysts and protect the integrity of the 
filters and finished water quality. Finally, the fourth concern is that 
the direct recycle of spent filter backwash without first providing 
treatment, equalization, or some form of hydraulic detention for the 
recycle flow, may cause plants to exceed State-approved operating 
capacity during recycle events. This can cause clarification and filter 
loading rates to be exceeded, which may lower overall oocyst removal 
provided by the plant and increase finished water oocyst 
concentrations.
    EPA has particular concerns regarding the direct recycle of spent 
filter backwash water as it is produced (i.e., recycle flow is not 
retained in an equalization basin, treatment unit, or other hydraulic 
detention unit prior to reintroduction to the main treatment process) 
for the following reasons:
    (1) Direct recycle may cause operating rates for clarification and 
filtration to be exceeded, which may lower overall Cryptosporidium 
removal;
    (2) Direct recycle may hydraulically upset some plants, lowering 
overall plant treatment performance, and;
    (3) Clarification and filtration operating rates may be exceeded at 
precisely the time recycle flow may be returning large numbers of 
oocysts to the treatment process.
    The impact of direct recycle practice to smaller plants with few 
filters is of greatest concern because return of recycle flow can 
double or triple plant influent flow, which may hydraulically overload 
the plant and reduce oocyst removal.
    Since standard disinfection practice does not inactivate 
Cryptosporidium, its control is entirely dependent on physical removal 
processes. The Agency is concerned that direct recycle may cause some 
plants to exceed operating capacity and thus lower their physical 
removal capabilities. This can increase the risk of oocysts entering 
the finished water and lead to an increased risk to public health.
    The limited data (Cornwell and Lee, 1993) EPA has identified 
regarding plants with existing equalization and/or treatment indicates 
they may be at no greater risk of hydraulic upset or degradation of 
oocyst removal performance than non-recycle plants. Given current data 
limitations, it is reasonable to assume the presence and utilization of 
adequate recycle flow equalization and/or treatment processes will 
alleviate the potential for hydraulic disruptions and the impairment of 
treatment performance. Data suggesting otherwise is currently 
unavailable.
    The potential for recycle to return significant numbers of oocysts 
to the treatment train does provide a general basis for concern 
regarding the impact of recycle practice to finished water quality. 
However, the Agency does not currently believe data warrants a national 
regulation requiring all recycle plants to provide recycle flow 
equalization or treatment for the following reasons:
    (1) Data correlating oocyst occurrence in recycle streams to 
increased oocyst occurrence in finished water is unavailable;
    (2) Data regarding the response of full-scale plants to recycle 
events is limited;
    (3) Data is not available to determine the level of recycle flow 
equalization or treatment full-scale systems may need, if any, to 
control the risk of oocysts entering finished water, and;
    (4) Whether and the extent to which oocyst occurrence in source 
water influences the necessary level of recycle treatment and 
equalization is unknown.
    The Agency believes requiring plants that may be at greater risk 
due to recycle, such as direct recycle plants and direct filtration 
plants, to characterize their recycle practice and provide data to the 
State for its review provides a cost effective opportunity to increase 
public health protection and supply a measure of safety to finished 
drinking water supplies. EPA believes that today's proposal will 
address potentially higher risk recycle situations that may threaten 
the performance of some systems, and will do so by allowing State 
drinking water programs to consider site-specific treatment conditions 
and needs. The Agency believes these recycle provisions are needed to 
protect plant performance, the quality of finished water supplies, and 
to provide an additional measure of public health protection.
1. Treatment Processes That Commonly Recycle and Recycle Flow 
Occurrence Data
a. Treatment Processes That Commonly Recycle
    The purpose of this section is to provide general background on 
common treatment plant processes, fundamental plant operations, and the 
origin of plant recycle streams. Detailed information on the specific 
recycle flows these processes generate are presented after this 
background discussion. Four general types of water treatment processes, 
conventional filtration, direct filtration, softening, and contact 
clarification, are discussed. Although there are numerous variations of 
these four treatment processes, only the most basic configurations are 
discussed here. The operation of package plants and options to 
returning recycle to the treatment process are also summarized.
i. Conventional Treatment Plants
    Conventional water filtration plants are defined by the use of four 
essential unit processes: Rapid mix, coagulation/flocculation, 
sedimentation, and filtration. Sedimentation employs gravity settling 
to remove floc and particles. Particles not removed by sedimentation 
may be removed by the filters. Periodically, accumulated solids must be 
removed from the sedimentation unit. These solids, termed 
``residuals,'' are currently disposed to sanitary sewer, treated with 
gravity thickening, or some other process prior to returning them to 
plant headworks or other locations in the treatment train. 
Clarification processes other than sedimentation may also be used, and 
they also produce process residuals.
    Clarification sludge may be processed on-site if the plant is 
equipped with solids treatment facilities. Commonly employed treatment 
processes include thickeners, dewatering equipment (e.g., plate and 
frame presses, belt filter presses, or centrifuges), and lagoons. Each 
of these processes produces residual water streams that are currently 
returned to the treatment process at the

[[Page 19099]]

headworks or other locations prior to filtration. The volume of 
residuals produced by clarification depends upon the amount of solids 
present in the raw water, the dose and type of coagulant applied, and 
the concentration of solids in the treated water stream.
    The one residual stream associated with filtration, spent filter 
backwash water, is produced during periodic backwashing events 
performed to remove accumulated solids from the filter. Spent filter 
backwash is frequently returned to the treatment process at the head of 
the plant, other locations prior to the filters, or disposed of to 
sanitary sewer or surface water. Some plants have the capability to 
send the filtrate produced during the filter ripening period to plant 
headworks, a raw water reservoir, or to a sanitary sewer or surface 
water rather than to the clear well as finished water. This practice, 
referred to as ``filter-to-waste'' is used to prevent solids, which 
pass through the filter more easily during the ripening period, from 
entering the finished water.
    Filter backwash operations can differ significantly from plant to 
plant. The main variables are the time between backwashes (length of 
filter run), the rate of backwash flow, the duration of the backwash 
cycle, and the backwashing method. The time between filter backwashes 
is generally a function of either run time, headloss, or solids 
breakthrough. Both headloss and solids breakthrough can be dependent 
upon the quality of the sedimentation effluent. Regardless of the 
variable driving backwash frequency, the interval between backwashes 
typically vary from 24 to 72 hours. Recommended backwash frequency is 
every 24-48 hours (ASCE/AWWA, 1998).
    There are a number of different methods that can be used to 
backwash a filter. These include: Upflow water only, upflow water with 
surface wash, and air/water backwash. Air/water backwash systems 
typically use 30-50 percent less water than the other two methods. The 
filter backwash flow rate can vary, depending on media type, water 
temperature, and backwash method, but generally has a maximum of 15-23 
gpm/ft\2\ (air/water backwash may have a lower maximum rate of 6-7 gpm/
ft\2\). A number of different backwash sequences are employed, but a 
typical backwash consists of a low rate wash (6-7 gpm/ft\2\ for several 
minutes), followed by a high rate wash (15-23 gpm/ft\2\ for 5-15 
minutes), which is then followed by a final low rate wash (6-7 gpm/
ft\2\ for several additional minutes). Some treatment plants only use a 
high rate wash for 15 to 30 minutes. Backwash rates are significantly 
higher than filtration rates, which vary from 1 to 8 gpm/ft\2\.
ii. Direct Filtration Plants
    The direct filtration process is similar to conventional treatment, 
except the clarification process is not present. Direct filtration 
plants produce the same filter residual as conventional filtration 
plants, namely filter backwash, and may also generate a filter-to-waste 
flow. Direct filtration plants do not produce clarification residuals 
because clarification is not employed. Filter backwash may be either 
recycled to the head of the plant or discharged to surface waters or a 
sanitary sewer. Although direct filtration plants generally treat 
source waters that have low concentrations of suspended material, the 
solids loading to the filters may be higher than at conventional plants 
because solids are not removed in a clarification process prior to 
filtration. If spent filter backwash is not treated to remove solids 
prior to recycle, solids loading onto the filters will continue to 
increase over time, as an exit from the treatment process is 
unavailable. Filter run length may be shorter in some direct filtration 
plants relative to conventional plants because the solids loading to 
the filters may be higher due to the lack of a clarification process. 
The concentration of solids in the source water is a key variable in 
filter run length.
iii. Softening Plants
    Softening plants utilize the same basic treatment processes as 
conventional treatment plants. Softening plants remove hardness 
(calcium and magnesium ions) through precipitation, followed by solids 
removal. Many softening plants employ a two-stage process, which 
consists of a rapid mix-flocculation-sedimentation sequence, in series, 
followed by filtration. Others use a single stage process, resembling 
conventional treatment plants. Precipitation of the calcium and 
magnesium ions is accomplished through the addition of lime (calcium 
hydroxide), with or without soda ash (sodium carbonate), which reacts 
with the calcium and magnesium ions in the raw water to form calcium 
carbonate and magnesium hydroxide. The precipitation of the calcium 
carbonate can be improved by recirculating some of the calcium 
carbonate sludge into the rapid mix unit because the additional solids 
provide nucleation points for the precipitation of calcium and 
magnesium. Without this recirculation, additional hydraulic detention 
time in the flocculation and sedimentation basins may be required to 
prevent excessive scale deposits in the plant clearwell or in the 
distribution system.
    A softening plant generally has the same residual streams as a 
conventional plant: Filter backwash, sedimentation solids, and 
thickener supernatant and dewatering liquids. A filter-to-waste flow 
may also be generated. These residual streams are either disposed or 
recycled within the plant. A portion of the sedimentation basin solids 
are commonly recycled as the sedimentation basin solids contain 
significant quantities of precipitated calcium carbonate, recycle of 
these solids reduces the required chemical dose. Solids are generally 
recycled into the rapid mix chamber to maximize their effectiveness.
iv. Contact Clarification Plants
    In the contact clarification process, the flocculation and 
clarification (and often the rapid mix) processes are combined in one 
unit, an upflow solids contactor or contact clarifier. Contact 
clarifiers are employed in both softening and non-softening processes. 
Raw water flows into the contact clarifier at the top of the central 
compartment, where chemical addition and rapid mix occurs. The water 
then flows underneath a skirt and into the outer sedimentation zone 
where solid separation occurs. A large portion of previously settled 
solids from the sedimentation zone is circulated to the mixing zone to 
enhance flocculation. The remainder of the solids are disposed to 
prevent their accumulation. Circulation and disposal of accumulated 
solids allows clarifier loading rates to be 10 to 20 times greater than 
loading rates for conventional sedimentation basins. Solids 
recirculation rates are generally different for softening and turbidity 
removal applications, with rates of up to 12 times the raw water flow 
for softening processes and up to 8 times the raw water flow for non-
softening processes (ASCE/AWWA, 1998). Following clarification, treated 
water from the contactor is then filtered.
    The residual streams from contact clarification plants are similar 
to those for conventional filtration plants. They include filter 
backwash, clarification solids, thickener supernatant, and dewatering 
liquids. The key operational consideration for these types of systems 
is the maintenance of a high concentration of solids within the skirt 
to allow high loading rates while maintaining adequate solids removal. 
Solids recirculation (e.g., recycle) helps contact clarification 
processes maintain the necessary solids concentration.

[[Page 19100]]

Softening plants may also generate filter to waste flow.
v. Package Plants
    Package plants are typically used to produce between a few thousand 
to 1 million gallons of water per day. Package plants can employ a 
conventional treatment train, as well as proprietary unit processes. 
Package plants typically include the same processes found in large 
plants, including coagulation, flocculation, clarification and 
filtration. The potential recycle streams are also comparable. The 
recycle of filter backwash may occur, however, the typical package 
plant may not be designed to convey process streams back into the plant 
as recycle.
vi. Summary of Recycle Disposal Options
    Two recycle disposal options available to some plants are direct 
discharge to sanitary sewers or discharge to surface waters. Discharge 
of recycle waters to the municipal sewer system may occur when the 
treatment plant and Publicly Owned Treatment Works (POTW) are under the 
same authority or when the plant has access to a sanitary sewer and a 
POTW agrees to accept its discharge.
    There may be a fee associated with discharge to a sanitary sewer 
system, and the total fee may vary with the volume of backwash effluent 
discharged as well as the amount of solids in the effluent (Cornwell 
and Lee, 1994). In addition to the fee requirement, discharging into 
the sewer system may require the plant to equalize the effluent prior 
to discharging to the POTW. The equalization process requires holding 
the effluent in tanks and gradually releasing it into the sanitary 
sewer system. The fee associated with sanitary sewer discharge may 
influence whether a plant recycles to the treatment process or 
discharges to a sanitary sewer.
    Another option to recycle within the treatment process is the 
direct discharge of recycle flow to surface waters, such as creeks, 
streams, rivers, and reservoirs. Direct discharge is a relatively 
common method of disposal for water treatment plant flows. A National 
Pollutant Discharge Elimination System (NPDES) permit requires that 
certain water quality conditions be met prior to the discharge of 
effluent into surface waters. Treatment of the effluent prior to 
discharge may be required. The cost of effluent treatment may influence 
whether plants recycle within the treatment process or discharge to 
surface water.
b. Recycle Flow Occurrence Data
    EPA has not regulated recycle flows in previous rulemakings. The 
1996 SDWA Amendments have lead the Agency to perform an examination of 
recycle flow occurrence data for the first time. EPA discovered through 
its literature search and its work with AWWA, AWWSCo., and Cincinnati 
Water Works to develop the issue papers, that the amount of recycle 
stream occurrence data available is very limited, particularly for 
Cryptosporidium, the primary focus of this regulation. This may be 
because Cryptosporidium was identified as a contaminant of concern 
relatively recently and because currently available oocyst detection 
methods have limitations.
    Twelve issue papers were developed to compile information on 
several commonly produced recycle streams. Each individual paper 
summarizes how the recycle stream is generated, the typical volume 
generated, characterizes the occurrence of various recycle stream 
constituents to the extent data allows, (i.e., occurrence of 
Cryptosporidium and inorganic and organic material), and briefly 
discusses potential impacts of recycling the stream. The discussion of 
potential impacts is usually brief, due to overall data limitations and 
particularly due to a lack of data on Cryptosporidium occurrence. The 
12 recycle streams examined include:
     untreated spent filter backwash water
     gravity settled spent filter backwash water
     combined gravity thickener supernatant (spent filter 
backwash and clarification process solids)
     gravity thickener supernatant from sedimentation basin 
solids
     mechanical dewatering device concentrate
     untreated basin solids
     lagoon decant
     sludge drying bed leachate
     monofill leachate membrane concentrate
     ion exchange regenerate
     minor streams
    A total of 112 references were used to complete the issue papers, 
and AWWSCo. and Cincinnati Water Works performed sampling of non-
microbial recycle stream constituents to supplement occurrence 
information.
    Cryptosporidium occurrence data was only identified for five 
recycle streams, namely: untreated spent filter backwash water, gravity 
settled spent filter backwash water, untreated sedimentation basin 
solids, combined thickener supernatant, and sludge drying bed leachate. 
Oocysts may occur in the other recycle streams as well, but published 
occurrence data was not identified. The issue papers and supporting 
literature indicate data does not exist to correlate oocyst occurrence 
in recycle streams to the occurrence of oocysts in finished water. 
However, the issue papers did identify data showing that oocysts occur 
in recycle streams, often at concentrations higher than that of the 
source water.
    Cryptosporidium is not the only constituent of recycle waters. 
Other common constituents are manganese, iron, aluminum, disinfection 
byproducts, organic carbon, Giardia lamblia and particles. EPA does not 
currently have data to indicate these constituents occur in recycle 
streams at levels which threaten treatment plant performance, finished 
water quality, or public health. Additionally, current regulations may 
largely control any minor risk these constituents may present. For 
example, organic matter in recycle flow may form disinfection 
byproducts in the presence of oxidants. The Stage 1 DBPR, which 
requires monitoring for disinfection byproducts, will identify systems 
experiencing disinfection byproduct occurrence above or near applicable 
MCLs through distribution system monitoring. Additionally, Secondary 
Maximum Contaminant Levels (SMCLs) have been promulgated to control 
occurrence of aluminum, iron, and manganese at levels of .05-.2 mg/l, 
.3 mg/l, and .05 mg/l, respectively. Particle levels are controlled by 
effluent turbidity standards and Giardia lamblia is controlled through 
a combination of disinfection and filtration requirements. EPA believes 
existing regulations control these recycle stream constituents. 
Therefore, their control is not a primary goal of today's proposal. 
Additionally, detailed discussion of these constituents is not provided 
in the below summary of the issue papers because: (1) control of 
Cryptosporidium is the focus of the recycle provisions, and; (2) 
concentrations of inorganic and organic materials reported in the issue 
papers are for recycle streams, not finished water occurrence. The 
recycle stream concentrations will be significantly diluted by mixing 
with source water.
    The occurrence of recycle flow constituents other than 
Cryptosporidium is not discussed in today's preamble for the above 
reasons. The following discussion of recycle stream occurrence data 
covers only untreated spent filter backwash water, gravity settled 
spent filter backwash water, combined gravity thickener

[[Page 19101]]

supernatant (a combination of spent filter backwash and clarification 
process solids), gravity thickener supernatant from clarification 
process solids, and mechanical dewatering device liquids. These five 
recycle streams are discussed in detail because they are most likely to 
present a threat to treatment plant performance or finished water 
quality when recycled. For example, treated and untreated spent filter 
backwash water and thickener supernatant are the only two recycle 
streams of sufficient volume to cause plants to exceed their operating 
capacity during recycle events. The five recycle streams discussed 
below are also most likely to contain Cryptosporidium.
    Copies of all the issue papers are available for public review in 
the Office of Water docket for this rulemaking. Portions of the 
following recycle stream descriptions use excerpts from the issue 
papers.

i. Untreated Spent Filter Backwash Water

    Water treatment plants that employ rapid granular filtration (e.g., 
conventional, softening, direct filtration, contact clarification) 
generate spent filter backwash water. The backwash water is generated 
when water is forced through the filter, counter-current to the flow 
direction during treatment operations, to dislodge and remove 
accumulated particles and pathogens residing in the filter media. 
Backwash rates are typically five to eight times the process rate, and 
are used to clean the filter at the end of a filter run, which is 
generally 24 to 72 hours in length. Backwash operations usually last 
from 10 to 25 minutes. The flow rate and duration of backwashing are 
the primary factors that determine the volume of backwash water 
produced. Once the backwashing process is complete, the backwash water 
and entrained solids are either disposed of to a sanitary sewer, 
discharged to a surface water, or returned to the treatment process. 
Plants currently return spent filter backwash to the treatment process 
at a variety of locations, usually between plant headworks and 
clarification. Data regarding common recycle return locations is 
discussed in the next section of this preamble.
    Spent filter backwash can be returned to the treatment process 
directly as it is produced, be detained in an equalization basin, or 
passed through a treatment process, such as clarification, prior to 
being returned to the plant. On a daily basis, spent filter backwash 
can range from 2 to 10 percent of plant production. Spent filter 
backwash is usually produced on an intermittent basis, but large plants 
with numerous filters may produce it continuously. At small and mid-
size plants, large volume, short duration flows of spent filter 
backwash are usually produced. This may cause some plants, particularly 
smaller plants that recycle directly without flow equalization or 
treatment, to exceed their operating capacity or to experience 
hydraulic disruptions, both of which may negatively impact treatment 
efficiency and oocyst removal.
    The concentrations of Cryptosporidium reported in the untreated 
spent filter backwash issue paper ranges from non-detect to a 
concentration of 18,421 oocysts per 100 L. This range is not amenable 
to formal statistical analysis, but rather provides a summary of 
minimum and maximum oocyst concentrations reported in available 
literature. Although a few studies report isolated data points of 
greater than 10,000 oocysts/100L for filter backwash water (Rose et 
al., 1989; Cornwell and Lee, 1993; Colbourne, 1989), occurrence studies 
that collected the largest number of samples reported mean filter 
backwash oocyst occurrence concentrations of a few hundred oocysts per 
100L (States et al., 1997; Karanis et al., 1996). The high 
concentration of oocysts found in some spent filter backwash samples is 
cause for concern, because oocysts are not inactivated by standard 
disinfection practice. They remain a threat to pass through the plant 
into the finished water if they are returned to the treatment process. 
However, current oocyst detection methods do not allow the occurrence 
of oocysts in spent filter backwash water to be correlated to finished 
water oocyst concentrations for a range of plant types, source water 
qualities, and recycle practices. Today's proposal does not require the 
installation of recycle equalization or treatment for spent filter 
backwash water on a national basis due to these data limitations.
    The Agency is concerned that certain recycle practices, such as 
returning spent filter backwash to locations other than prior to the 
point of primary coagulant addition, or hydraulically overloading the 
plant with recycle flow so it exceeds its State approved operating 
capacity, may present risk to finished water quality and public health. 
Exceeding plant operating capacity during recycle events may cause 
greater risk to finished water quality, because plant performance is 
potentially being lowered at precisely the time oocysts are returned to 
the plant in the recycle flow. To address this concern, today's 
proposal requires that certain direct recycle plants that recycle spent 
filter backwash water and/or thickener supernatant to perform a self 
assessment of their recycle practice and report the results to the 
State. The self assessment requirements are discussed in detail later 
in this preamble.

ii. Gravity Settled Spent Filter Backwash Water

    Gravity settled spent filter backwash water is generated by the 
same filter backwash process and is produced in the same volume as 
untreated spent filter backwash water. The difference between the two 
streams is that the former is treated by gravity settling prior to its 
return to the primary treatment process. Sedimentation treatment is 
usually accomplished by retaining the spent filter backwash water in a 
treatment unit for a period of time to allow suspended solids 
(including oocysts) to settle to the bottom of the basin. Polymer may 
be used to improve process efficiency. The water that leaves the basin 
is gravity settled spent filter backwash water. Removing solids from 
the spent filter backwash causes only a minor reduction in volume as 
the solids content of the untreated stream is low, usually below 1 
percent.
    Providing gravity settling for spent filter backwash is 
advantageous for two reasons. First, the sedimentation process detains 
the spent filter backwash in treatment basins for a period of hours, 
which lowers the possibility a large recycle volume will be returned to 
the plant in a short amount of time and cause the plant operating 
capacity to be exceeded. Second, treating the spent filter backwash 
flow can remove Cryptosporidium oocysts from the flow, which will 
reduce the number of oocysts returned to the plant.
    Limited data show that sedimentation can effectively remove 
oocysts. Cornwell and Lee (1993) conducted limited sampling of spent 
filter backwash water at two plants prior to and after sedimentation 
treatment. The first facility practiced direct filtration and was 
sampled twice. The Cryptosporidium concentrations into and out of the 
sedimentation basin treating spent filter backwash were 900/100L and 
140/100L, respectively, for the first sampling and 850/100L in the 
influent and 750/100L in the effluent for the second sampling. At the 
second plant a sludge settling pond received both sedimentation basin 
sludge and spent filter backwash, and the spent filter backwash oocyst 
concentration was 16,500/100L, and the treated recycle water 
concentration was 420/100L. In a study by Karanis (1996), 
Cryptosporidium was regularly detected in settled backwash waters. Of 
the 50

[[Page 19102]]

samples collected, 82 percent tested positive for Cryptosporidium. The 
mean value for Cryptosporidium was 22 oocysts/100L.
    Sedimentation treatment can remove oocysts from spent filter 
backwash, but data indicate oocysts remain in gravity settled spent 
filter backwash water even after treatment. The Agency believes that 
sedimentation treatment for spent filter backwash waters is capable of 
removing oocysts and improving the quality of the water prior to 
recycle. However, given current data limitations, the Agency does not 
believe it is possible to specify, in a national regulation, the 
conditions (e.g., source water oocyst concentrations, primary treatment 
train performance, concentration of oocysts in spent filter backwash, 
ability of sedimentation to remove oocysts under a range of conditions) 
under which sedimentation treatment of spent filter backwash water may 
be appropriate. This decision is best made by State programs to allow 
consideration of site-specific conditions and treatment needs.

iii. Combined Gravity Thickener Supernatant

    Combined gravity thickener supernatant is derived from the 
treatment of filter backwash water and sedimentation basin solids in 
gravity thickener units. These two flows may not reside in the 
thickener at the same time or in equal volumes, depending on plant 
operations. The volume of thickener supernatant generated at a water 
treatment plant is a function of the type of flows it treats, the 
solids content of the influent stream, and the method of thickener 
operation. Regardless of whether a continuous or a batch process is 
used, a number of factors, including residuals production (a function 
of plant production, raw water suspended solids, and coagulant dose), 
volume of spent filter backwash water produced, and the level of 
treatment provided to thickener influent streams, directly affect the 
quantity of thickener supernatant produced.
    The flow entering the thickener is primarily spent filter backwash 
water. Sedimentation basin solids is the second largest flow. Flow from 
dewatering devices, which is generated by the dewatering of residuals, 
may comprise a minor volume entering the thickener. Combined thickeners 
will have an influent that may be eighty-percent spent filter backwash 
or more by volume. About eighty-percent of the solids entering the 
thickener will be from the sedimentation basin sludge, as spent filter 
backwash water has a comparatively low solids concentration.
    A recent FAX survey (AWWA, 1998) identified more than 300 water 
treatment plants in the United States with production capacities 
ranging from less than 2 mgd to greater than 50 mgd that recycle spent 
filter backwash water. Many of the survey respondents indicated that 
they recycle more than just spent filter backwash water. Based on the 
survey and published literature, thickener supernatant is probably the 
second largest and second most frequently recycled stream at water 
treatment facilities after spent filter backwash.
    Data summarized in the issue paper showed that thickener 
supernatant quality varies widely, due in large part because the type 
and quality of recycle streams entering thickeners varies over time and 
from plant to plant. The turbidity, total suspended solids, and 
particle counts of thickener effluent are directly impacted by the 
quality of water loaded onto the thickener, thickener design, and 
thickener operation (e.g., residence time, use of polymer).
    Data on the occurrence of Cryptosporidium was limited to two 
samples, with oocyst occurrence ranging from 82 to 420 oocysts per 100 
L. Data is too limited, and practice varies too widely, to draw 
conclusions on the impact recycle of this flow may have on plant 
performance. However, given that the contents of the thickener have 
been treated and the amount of flow produced by gravity thickeners is 
relatively modest, it may be feasible to recycle the flow in a manner 
that minimizes adverse impact. Additionally, treatment plant personnel 
have a vested interest in optimizing thickener operation to minimize 
sludge dewatering and handling costs; optimization of thickener 
operation is likely to assist oocyst removal. However, additional data 
is needed to characterize the occurrence of Cryptosporidium and the 
potential impact recycle of combined thickener supernatant may have on 
finished water quality.

iv. Gravity Thickener Supernatant from Sedimentation Solids

    Gravity settled sedimentation basin solids are sedimentation basin 
solids that have undergone settling to allow solid sludge components to 
settle to the bottom of a gravity thickener. The supernatant from the 
thickener is a potential recycle flow. The tank bottom is sloped to 
enhance solids thickening and collection and removal of settled solids 
is accomplished with a bottom scraper mechanism. If the supernatant is 
recycled, it can be returned to the plant continuously or 
intermittently, depending on whether the thickener is operated in batch 
mode. Thickeners may receive and treat both spent filter backwash water 
and sedimentation basin solids. For purposes of this discussion, and 
the data presented in the issue paper, the gravity thickener is only 
receiving sedimentation basin solids.
    The volume of treated sedimentation basin solids supernatant 
generated is dependent on the amount of sludge produced in the 
sedimentation basin, the solids content of the sludge, and method of 
thickener operation. Sludge production is a function of plant 
production, raw water suspended solids, coagulant type, and coagulant 
dose. The quantity of sedimentation basin sludge supernatant is 
approximately 75 to 90 percent of the original volume of sedimentation 
basin sludge produced.
    There is a very limited amount of data on the quality of thickener 
supernatant produced by gravity settling of only sedimentation basin 
solids (i.e., spent filter backwash and other flows are not added to 
the thickener), and no data was identified regarding the concentration 
of Cryptosporidium that occur in the supernatant. As is the case with 
combined gravity thickener supernatant, it is difficult to determine 
what impact, if any, the return of the supernatant may have on plant 
operations and finished water quality due to limited data. Additional 
data is necessary to determine the concentration of oocysts in this 
recycle stream, and to characterize the impact its recycle may have to 
plant performance.

v. Mechanical Dewatering Device Liquids

    Water treatment plant residuals (usually thickened sludge) are 
usually dewatered prior to disposal to remove water and reduce volume. 
Two common mechanical dewatering devices used to separate solids from 
water are the belt filter press, which compresses the residuals between 
two continuous porous belts stretched over a series of rollers, and the 
centrifuge, which applies a strong centrifugal force to separate solids 
from water. The plate and frame press is another dewatering device that 
contains a series of filter plates, supported and contained in a 
structured frame, which separate sludge solids from water using a 
positive pressure differential as the driving force. Water removed from 
the solids with a belt filter press is called filtrate, from a filter 
press it is called pressate, and the water separated from the residuals 
with a centrifuge is referred to as centrate.

[[Page 19103]]

These streams will be collectively referred to as ``dewatering liquid'' 
for the following discussion.
    The volume of dewatering liquid produced depends primarily on the 
volume and solids content of the thickened residuals fed to the 
mechanical dewatering device. Plants that produce small sludge volumes, 
and hence a low volume of thickener residuals, will process fewer 
residuals in the mechanical dewatering device and hence produce a 
smaller volume of dewatering liquid than a plant producing a large 
volume of solids, all else being equal. Since residuals are often 
thickened (typically to about 2 percent solids) prior to dewatering, 
the volume of the dewatering device feed stream is significantly lower 
than the volume of sedimentation basin residuals generated. If the 
sedimentation basin sludge flow is assumed to be 0.6 percent of plant 
production, then dewatering device flow may be approximately 0.1 to 0.2 
percent of plant flow. Generally these streams are mixed in with other 
recycle streams prior to being returned to the plant. Mechanical 
dewatering devices may be operated intermittently, after a suitable 
volume of residuals have been produced for dewatering. The production 
of dewatering liquid and its recycle may not be a continuous process.
    Data on the constituents in dewatering liquid were found in three 
references, one on belt filter press liquids, one on plate and frame 
pressate, and one on centrifuge centrate. Data on the occurrence of 
Cryptosporidium was not identified. Given the small, intermittent flow 
produced by mechanical dewatering devices, recycle flows from them are 
unlikely to cause plants to exceed operating capacity. However, it is 
possible that dewatering device liquid contains Cryptosporidium because 
it derived from solids likely to hold a large numbers of oocysts. 
Additional data is necessary to determine the concentration of oocysts 
in this recycle stream, and to characterize any impact its recycle may 
have to plant performance.
2. National Recycle Practices
a. Information Collection Rule
    Public water systems affected by the ICR were required to report 
whether recycle is practiced and sample washwater (i.e., recycle flow) 
between the washwater treatment plant (if one existed) and the point at 
which recycle is added to the process train. Sampling of plant recycle 
flow was required prior to blending with the process train. Monthly 
samples were required for pH, alkalinity, turbidity, temperature, 
calcium and total hardness, TOC, UV254, bromide, ammonia, 
and disinfectant residual if disinfectant was used. Systems were also 
required to measure recycle flow at the time of sampling, the twenty 
four hour average flow prior to sampling, and report whether treatment 
of the recycle was provided and, if so, the type of treatment. 
Reportable treatment types were plain sedimentation, coagulation and 
sedimentation, filtration, disinfection, or a description of an 
alternative treatment type. Plants were also required to submit a plant 
schematic to identify sampling locations. EPA used the sampling 
schematics and other reported information to compile a database of 
national recycle practice.

i. Recycle Practice

    The Agency developed a database from the ICR sampling schematics 
and other reported information. Table IV.10 summarizes the plants in 
the database. Of the 502 plants in the database at the time the 
analysis was performed, 362 used rapid granular filtration.

              Table IV.10.--Recycle Practice at ICR Plants
------------------------------------------------------------------------
                      Plant classification                        Number
------------------------------------------------------------------------
All ICR plants.................................................      502
Filtration plants \a\..........................................      362
Filtration plants recycling \b\................................      226
Filtration plants treating recycle.............................      148
Recycle plants serving 100,000......................      168
Recycle plants serving 100,000.................................      58
------------------------------------------------------------------------
\a\ Defined as conventional, lime softening, other softening, and direct
  filtration plants.
\b\ Plants report existence of a recycle stream, not its origin.

    These plants are classified as conventional, lime softening, other 
softening, and direct filtration. The remaining 140 plants in the 
database do not employ rapid granular filtration capability and 
generally provide disinfection for ground water. Of the 362 filtration 
plants in the database, 226 (62.4 percent) reported recycling to the 
treatment process. Seventy-four percent of the plants that recycle 
serve populations greater than 100,000 and 26 percent serve populations 
below 100,000. Figure IV.9 shows the distribution of plants by 
treatment type and Figure IV.10 shows the distribution of plants by 
population served. Table IV.11 shows that 88 percent of ICR recycle 
plants use surface water. An additional one percent use GWUDI and 
another one percent use a combination of ground water and surface 
water. Therefore, 90 percent of ICR recycle plants use a source water 
that could contain Cryptosporidium.
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          Table IV.11.--Source Water Use by ICR Recycle Plants
------------------------------------------------------------------------
                                                              Percent of
               Source water type                 Number of     recycle
                                                   plants       plants
------------------------------------------------------------------------
Total number of recycle plants................          226          100
Surface Water.................................          199           88
Ground water under the influence..............            3            1
Ground water and surface water................            2            1
Ground water only.............................           22           10
------------------------------------------------------------------------

    Table IV.12 shows that 65 percent of ICR recycle plants report 
providing treatment for the recycle flow. The percentage of plants 
providing treatment is the same for the subsets of plants serving 
greater than and less than 100,000 people. Sedimentation is the most 
widely reported treatment method, as 77 percent of plants providing 
treatment employ it. The database does not provide information on the 
solids removal efficiency of the sedimentation units. All direct 
filtration plants practicing recycle reported providing treatment for 
the recycle flow.

          Table IV.12.--Treatment of Recycle at ICR Plants \1\
------------------------------------------------------------------------
                                             Number of     Percentage of
          ICR recycling plants                plants      recycle plants
------------------------------------------------------------------------
Number of recycle plants................             226             100
Practice recycle treatment..............             147              65
Use sedimentation.......................             114              77
Use sedimentation/coagulation...........              14              10
Use two or more treatments..............              14              10
Other treatment.........................               5              3
------------------------------------------------------------------------
\1\ Disinfection not counted as treatment because it does not inactivate
  Cryptosporidium.

    Table IV.13 indicates that 75 percent of ICR recycle plants return 
recycle prior to rapid mix. Fifteen percent return it prior to 
sedimentation, and ten percent of plants return it prior to filtration. 
These percentages hold for the subsets of plants serving greater than 
and less than 100,000 people. The data indicate that introducing 
recycle prior to rapid mix may be a common practice. EPA believes that 
introducing recycle flow prior to the point of primary coagulant 
addition, is the best recycle return location because it limits the 
possibility residual treatment chemicals in the recycle flow will 
disrupt treatment chemistry.

                   Table IV.13.--Recycle Return Point
------------------------------------------------------------------------
                                             Number of      percent of
         Point of recycle return              plants          plants
------------------------------------------------------------------------
Number of recycle plants................          \1\224             100
Prior to point of primary coagulant                  169              75
 addition...............................
Prior to sedimentation..................              34              15
Prior to filtration.....................              21             10
------------------------------------------------------------------------
\1\ Recycle return point could not be determined for two plants.

    The data provides the following conclusions regarding the recycle 
practice of ICR plants: (1) The recycle of spent filter backwash and 
other process streams is a common practice; (2) the great majority of 
recycle plants in the database use filtration and surface water 
sources; (3) a majority of plants in the database that recycle provide 
treatment for recycle flow, and; (4) a large majority of plants in the 
database that recycle (approximately 3 out of 4) recycle prior to the 
point of primary coagulant addition.
b. Recycle FAX Survey
    The AWWA sent a FAX survey (AWWA, 1998) to its membership in June 
1998 to gather information on recycle practices. Plants were not 
targeted based on source water type, the type of treatment process 
employed, or any other factor. The survey was sent to the broad 
membership to increase the number of responses. Responses indicating a 
plant recycled spent filter backwash or other flows were compiled to 
create a database. The resulting database included 335 plants. The 
database does not contain information from respondents who reported 
recycle was not practiced. Data from some of the FAX survey respondents 
also populates the ICR database. Plants in the database are well 
distributed geographically and represent a broad range of plant sizes 
as measured by capacity. Figure IV.11 shows plant distribution by 
capacity and Figure IV.12 by geographic location. The following 
discussion of FAX survey data is divided into two sections. The first 
discusses national recycle practice and the second discusses options 
for recycle disposal in lieu of returning recycle to the treatment 
process.
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i. Recycle practice
    Data summarized in Table IV.14 show that 78 percent of plants in 
the database rely on a surface water as their source. The percentage of 
plants using source water influenced by a surface water (which may 
contain Cryptosporidium) could be higher because the data do not report 
whether wells were pure ground water or GWUDI.

          Table IV.14.--Source Water Used by FAX Survey Plants
------------------------------------------------------------------------
                                                                 Percent
                       Source water type                           of
                                                                 plants
------------------------------------------------------------------------
Surface Water.................................................        78
River.........................................................        27
Reservoir.....................................................        28
Lake..........................................................        16
Other.........................................................         7
Well \1\......................................................       22
------------------------------------------------------------------------
\1\ Wells sources not defined as either ground water or ground water
  under the direct influence of surface water.

    Table IV.15 shows that a wide variety of treatment process types 
are included in the data, with conventional filtration (rapid mix, 
coagulation, sedimentation, filtration) representing over half of the 
plants submitting data. Upflow clarification is the second most common 
treatment process reported. Ten percent of plants in the database use 
direct filtration. Only four percent of plants do not use rapid 
granular filtration.

           Table IV.15.--Treatment Trains of FAX Survey Plants
------------------------------------------------------------------------
                                                                Percent
                    Treatment process type                     of plants
                                                                  \1\
------------------------------------------------------------------------
Rapid mix, coagulation, filtration...........................         51
Upflow clarifier.............................................         21
Softening....................................................         14
Direct filtration............................................         10
Other........................................................         4
------------------------------------------------------------------------
\1\ 96 percent of plant in the database provide filtration.

    Table IV.16 indicates that a vast majority of plants recycle prior 
to the point of primary coagulant addition. Only six percent of plants 
returned recycle in the sedimentation basin or just prior to 
filtration.

         Table IV.16.--Recycle Return Point of FAX Survey Plants
------------------------------------------------------------------------
                                                                 Percent
                         Return point                              of
                                                                 plants
------------------------------------------------------------------------
Prior to point of primary coagulant addition..................        83
Pre-sedimentation (e.g., rapid mix)...........................        11
Sedimentation basin...........................................         4
Before filtration.............................................         2
------------------------------------------------------------------------

    Table IV.17 shows that the majority of plants in the database 
provide some type of treatment for the recycle flow prior to its 
reintroduction to the treatment process. Approximately 70 percent of 
plants reported providing treatment, with sedimentation being employed 
by over half of these plants. Equalization, defined as a treatment 
technology by the survey, is practiced by 20 percent of plants in the 
database. Fourteen percent of plants reported using both sedimentation 
and equalization.

          Table IV.17.--Recycle Treatment at FAX Survey Plants
------------------------------------------------------------------------
                                                                 Percent
                        Treatment type                             of
                                                                 plants
------------------------------------------------------------------------
No treatment..................................................        30
Treatment.....................................................        70
Sedimentation.................................................        54
Equalization..................................................        20
Sedimentation and equalization................................        14
Lagoon........................................................         5
Others........................................................         7
------------------------------------------------------------------------

    Table IV.18 summarizes recycle treatment practice and frequency of 
direct recycle based on population served. The table illustrates that, 
for plants supplying data, treatment of recycle with sedimentation is 
provided more frequently as plant service population deceases. Plants 
serving populations of less than 10,000 recycle directly (27.5 percent) 
less frequently than plants serving populations greater than 100,000 
(50 percent). The data indicate that a majority of small plants in the 
database may have installed equalization or sedimentation treatment to 
protect treatment process integrity from recycle induced hydraulic 
disruption. All direct filtration plants in the FAX survey provide 
recycle treatment or equalization.

                          Table IV.18.--Recycle Practice Based on Population Served \1\
----------------------------------------------------------------------------------------------------------------
                                                                           Recycle practice
                 Population served                  ------------------------------------------------------------
                                                      #Plants   Equalization    Sedimentation    Direct recycle
----------------------------------------------------------------------------------------------------------------
10,000.............................................        43        9% (n=4)       67% (n=29)        23% (n=10)
10,000-50,000......................................        79       10% (n=8)       57% (n=45)        33% (n=26)
50,000-100,000.....................................        35       17% (n=6)       54% (n=19)        29% (n=10)
100,000............................................        65      35% (n=23)       23% (n=15)       42% (n=27)
----------------------------------------------------------------------------------------------------------------
\1\ Based on 222 surface water plants suppling all necessary data to make determination.

    FAX survey data support the following conclusions regarding the 
recycle practice of plants supplying data: (1) The recycle of spent 
filter backwash and other process streams is a common practice; (2) the 
majority of recycle plants use surface water as their source and are 
thereby at risk from Cryptosporidium; (3) a large majority of plants 
providing data recycle prior to the point of primary coagulant 
addition, and; (4) a majority of plants supplying data provide 
treatment for recycle waters prior to reintroducing them to the 
treatment plant. The FAX survey provides an informative snapshot of 
national recycle practices due to the number of recycle plants it 
includes, the geographic distribution of respondents, and the good 
representation of plants serving populations of less than 10,000 
people.
ii. Options to recycle.
    The FAX survey asked whether feasible alternatives to recycle are 
available (i.e., NPDES surface water discharge permit, pretreatment 
permit for discharge to POTW) and the importance of recycle to 
optimizing treatment performance and meeting production requirements. 
Responses to these questions is summarized in Table IV.19.
    Table IV.19 shows that approximately 20 percent of respondents 
could not obtain either an NPDES surface water discharge permit or a 
pretreatment permit for discharge to a POTW. Approximately 90 percent 
of respondents stated that recycle flow is not important to meet 
typical demand.

[[Page 19110]]

Twenty-four percent of all respondents stated that returning recycle to 
the treatment process is important for optimal operation. ``Optimal 
operation'' was not defined by the survey and respondents may have 
considered not changing current plant operation (e.g., not changing 
current recycle practice) an aspect of optimal treatment, rather than 
addressing whether recycle practice is important for the plant to 
produce the highest quality finished water.

  Table IV.19.--Options to Recycle as Reported by FAX Survey Plants \1\
------------------------------------------------------------------------
                                          Percent    Percent    Percent
                Question                    Yes         No      Unknown
------------------------------------------------------------------------
Able to obtain NPDES surface discharge         41%        37%        22%
 permit?...............................    (n=131)    (n=120)     (n=70)
Able to obtain pretreatment permit for         43%        42%        15%
 POTW discharge?.......................    (n=137)    (n=136)     (n=48)
Can obtain either an NPDES or a POTW           60%      19.5%      20.5%
 discharge permit?.....................    (n=192)     (n=63)     (n=66)
Is recycle important to meet peak              14%        80%         6%
 demand?...............................     (n=44)    (n=257)     (n=20)
Is recycle important to meet typical            9%        85%         6%
 demand?...............................     (n=28)    (n=272)     (n=21)
Is recycle important to optimal                24%        70%         6%
 operation? (All plants in survey).....     (n=75)    (n=225)     (n=21)
Is recycle important to optimal                13%        83%         4%
 operation? \2\ (softening plants only)      (n=3)     (n=19)     (n=1)
------------------------------------------------------------------------
\1\ Number of plants varies from question to question due to different
  response rates.
\2\ Optimal operation not defined by survey. May include overall plant
  operation rather than importance of recycle to producing highest
  possible quality finished water.

iii. Conclusions
    The ICR and FAX survey data are complimentary, as the ICR data 
supplies a wealth of data regarding recycle practices at large capacity 
plants, while the FAX Survey provides data on recycle practices over a 
range of plant capacities. Taken together, the two data sets provide a 
good picture of current recycle practice. The data indicate that 
recycle is a common practice for plants sampled. Approximately half of 
the respondents providing data return recycle flow to the treatment 
process and 70 percent provide some type of recycle treatment. 
Sedimentation and equalization are the two most commonly employed 
treatment technologies for plants supplying data. Approximately 80 
percent of plants sampled return recycle prior to the point of primary 
coagulant addition. Examining the recycle practices of plants in the 
ICR and FAX survey data show that small plants (i.e., fewer than 10,000 
people served) are more than twice as likely as large plants (i.e., 
greater than 100,000 people served) to provide sedimentation for 
recycle treatment (58 versus 26 percent).
    The FAX survey responses show that approximately half of plants 
providing data have an option to recycle return, whether it be an NPDES 
surface water discharge permit or discharge to a POTW. Eighty-five 
percent of respondents stated that recycle flow is not important to 
meet peak demand. Less than a quarter of respondents have monitored 
pathogen concentrations in backwash water and fewer than half have any 
monitoring data to characterize the quality of the backwash water.
3. Recycle Provisions for PWSs Employing Rapid Granular Filtration 
Using Surface Water or Ground Water Under the Direct Influence of 
Surface Water
a. Return Select Recycle Streams Prior to the Point of Primary 
Coagulant Addition
i. Overview and Purpose
    Today's proposal requires that systems employing rapid granular 
filtration and using surface water or GWUDI as a source return filter 
backwash, thickener supernatant, and liquids from dewatering processes 
to the primary treatment process prior to the point of primary 
coagulant addition. The goal of this provision is to protect the 
integrity of chemical treatment and ensure these recycle streams are 
passed through as many physical removal processes as possible to 
provide maximum opportunity for removal of Cryptosporidium oocysts from 
the recycle flow. Since Cryptosporidium is resistant to standard 
disinfection practice, it is important that chemical treatment be 
optimized to protect treatment plant efficiency and that all available 
physical removal processes be employed to remove it.
    Today's proposal requires these flows be returned prior to the 
point of primary coagulant addition because these streams are either of 
sufficient volume to cause hydraulic disruption within the treatment 
process when recycled and/or are likely to contain Cryptosporidium 
oocysts. Minor recycle streams, such as lab sample lines, pump packing 
water, and infrequent process overflows are not likely to threaten 
plants' hydraulic stability or contain appreciable numbers of oocysts.
    Treatment plant types that need to return recycle to a location 
other than prior to the point of primary coagulant addition to maintain 
optimal treatment performance (optimal performance as indicated by 
finished water or intra-plant turbidity levels), plants that are 
designed to employ recycle flow as an intrinsic component of their 
operations, plants with very low influent turbidity levels that may 
need alternative recycle locations to obtain satisfactory suspended 
solids removal, or other types of plants constrained by unique 
treatment considerations, may apply to the State to recycle at an 
alternative location under today's proposal. Once approved by the 
State, plants may recycle to the specified location.
ii. Data
    Data from the ICR and FAX Survey indicate that 75 and 78 percent of 
plants, respectively, return recycle prior to the point of primary 
coagulant addition. The ``point of primary coagulant addition'' was 
defined in both analyses as the return of recycle prior to the rapid 
mix unit. The FAX Survey data indicate that 77 percent of plants 
serving under 10,000 people recycle prior to the point of primary 
coagulant

[[Page 19111]]

addition. It also showed that 78 percent percent of all plants in the 
database return recycle there, which suggests that plants serving 
smaller populations may return recycle prior to the point of primary 
coagulant addition as frequently as plants serving larger populations. 
Other common recycle return locations are the rapid mix unit, between 
rapid mix and clarification, or into the clarification unit itself.
    The Agency does not believe filter backwash, thickeners 
supernatant, or liquids from dewatering processes should be recycled at 
the point of primary coagulant addition or after it for three reasons:
    (1) Addition of these recycle streams, which can contain residual 
coagulant and other treatment chemicals, after the location of primary 
coagulant addition, may render the chemical dose applied less 
effective, potentially harming the efficiency of subsequent treatment 
processes;
    (2) Introduction of recycle into the flocculation unit or 
clarification unit may create hydraulic currents that exacerbate or 
create short circuiting, and;
    (3) Recycle introduced into the clarification process may not 
experience sufficient residence time for adequate solids removal to 
occur.
    The Agency is concerned that plants may not adjust chemical dosage 
during recycle events to account for: (1) The presence of a potentially 
significant amount of residual treatment chemical in recycle flow and 
changes in recycle flow quality, and; (2) potentially large 
fluctuations in plant influent flow during recycle events. EPA is 
concerned that changes in influent water quality and flow are not 
monitored on an instantaneous basis during recycle events. Since the 
chemistry of the recycle flow and source water may differ 
significantly, it is important plants mix source and recycle water to 
establish a uniform chemistry prior to applying treatment chemical so 
the dose is appropriate for the mixture. Additionally, wide fluctuation 
in plant influent flow during recycle events may cause chemical over-or 
under-dosing, which can lower overall oocyst removal efficiency. In an 
article concerning optimization of filtration performance, Lytle and 
Fox (1996) state, ``The capability to instantaneously monitor treatment 
processes and rapidly and effectively respond to raw and filter 
effluent quality changes are important factors in consistently 
producing low turbidity water.'' Logdson (1987) further states, ``For a 
plant to be operated properly, the total flow rate has to be known on 
an instantaneous basis or by volumetric measurement.'' EPA believes it 
is important plants diligently monitor the appropriateness of chemical 
dosing at all times, but particularly during recycle events, and strive 
for real-time chemical dose and influent flow management to optimize 
plant oocyst removal.
    Pilot-scale research conducted by Patania et al. (1995) to examine 
the optimization of filtration found that chemical pretreatment was the 
most important variable determining oocyst removal by filtration. 
Edzwald and Kelley (1998) performed pilot-scale work to determine the 
ability of sedimentation, DAF, and filtration to remove Cryptosporidium 
and found that coagulation is critical to effective Cryptosporidium 
control by clarification and filtration. Bellamy et al. (1993) stated 
that the most important factor in plant performance is the use of 
optimal chemical dosages. Coagulation was recognized as the single most 
important step in the process of water clarification by Conley (1965). 
Ten pilot scale runs performed by Dugan et al. (1999) showed that 
coagulation has a large influence on the log removal of Cryptosporidium 
achieved by sedimentation. The importance of proper coagulation to 
filter performance was noted by Robeck et al. (1964) in pilot and full-
scale work that showed proper coagulation is more important to the 
production of safe water than the filtration rate used. Results of 
direct filtration pilot studies, summarized by Trussell et al. (1980), 
showed that ``effective coagulant is absolutely necessary if good 
effluent qualities are to be consistently produced.''
    Given the critical role proper chemical dosing plays in maintaining 
effective clarification and filtration processes, the Agency believes 
it is prudent and necessary to minimize the possibility recycle of 
spent filter backwash, thickener supernatant, and dewatering liquids 
will render chemical dosages applied during recycle events inaccurate, 
due to the presence of residual chemical or variations in influent 
flow, by requiring they be returned prior to the point of primary 
coagulant addition.
    Finally, a fundamental tenet of water treatment is multiple 
treatment barriers should be provided to prevent microbial pathogens 
from entering finished water. To achieve this, conventional plants rely 
on coagulation, flocculation, clarification, and filtration as 
preventive microbial barriers. The Agency believes it is important that 
recycle waters be passed through each of these treatment processes to 
maximize the probability disinfection resistant oocysts will be removed 
in the plant and not enter the finished water supply.
iii. Proposed Requirements
    Today's proposal requires that rapid granular filtration plants 
using surface water or GWUDI as a source return filter backwash, 
thickener supernatant, and liquids from dewatering processes prior to 
the point of primary coagulant addition. Plants that require an 
alternative recycle return location to maintain optimal finished water 
quality (as indicated by finished water or intra-plant turbidity 
levels), plants that are designed to employ recycle flow as an 
intrinsic component of the treatment process, or plants with unique 
treatment requirements or processes may apply to the State to return 
recycle flows to an alternative location. Plants may utilize this 
alternative location once granted by the State. EPA will develop 
detailed guidance and make it available to States and PWSs.
    Softening systems may recycle process solids, but not spent filter 
backwash, thickener supernatant, or liquids from dewatering processes, 
at the point of lime addition immediately preceding the softening 
process to improve treatment efficiency. Literature establishes that 
return of process solids to point of lime addition decreases production 
of nuclei, increases the rate of crystallization, and increases crystal 
size, all of which enhance settling and process integrity (Randtke, 
1999; Snoeyink and Jenkins, 1980). Contact clarification systems may 
recycle process solids, but not spent filter backwash, thickener 
supernatant, or liquids from dewatering processes, directly into the 
contactor to improve treatment efficiency.
iv. Request for Comments
    EPA requests comment on the proposed requirements. The Agency also 
requests comment on the following aspects of this provision:
    (1) What regulatory options are available to ensure direct recycle 
plants practice real-time chemical dose and influent flow management? 
Should flow-paced coagulant feed be required at direct recycle plants 
to minimize potential harmful impacts of recycle? What regulatory 
requirements may be applicable to ensure the integrity of the 
coagulation process?
    (2) What treatment processes or treatment configurations may need 
an alternative recycle location to maintain optimal treatment?
    (3) What alternative recycle locations are appropriate for such 
treatment configurations and what location may be inappropriate?

[[Page 19112]]

    (4) Are there other reasons, beyond maintaining optimal treatment 
efficiency, to justify granting alternate recycle locations to plants? 
What are they?
    (5) What criteria, operating practices, or other parameters should 
be evaluated to determine whether an alternative recycle return 
location should be granted?
    (6) Does recycling at the point of primary coagulant addition, 
instead of prior to it, provide assurance that an appropriate dose of 
treatment chemicals will be consistently applied during recycle events? 
Is it necessary to mix the recycle and raw water prior to chemical 
addition to ensure a consistent water chemistry for chemical dosing?
    (7) Are there circumstances where it would be appropriate to allow 
systems to recycle at the point of primary coagulant addition?
b. Recycle Requirements for Systems Practicing Direct Recycle and 
Meeting Specific Criteria
i. Overview and Purpose
    Today's proposal requires that self assessments be performed at 
conventional filtration plants meeting all of the following criteria 
and the results of the self assessment reported to the State. The 
criteria are:
    (1) Use of surface water or GWUDI as a source;
    (2) Employ of 20 or fewer filters to meet production requirements 
during the highest production month in the 12 month period prior to 
LT1FBR's compliance date, and;
    (3) Recycle spent filter backwash or thickener supernatant directly 
to the treatment process (i.e., recycle flow is returned within the 
treatment process of a PWS without first passing the recycle flow 
through a treatment process designed to remove solids, a raw water 
storage reservoir, or some other structure with a volume equal to or 
greater than the volume of spent filter backwash water produced by one 
filter backwash event.)
    The goal of the self assessment is to identify those direct recycle 
plants that exceed their State approved operating capacity, on an 
instantaneous basis, during recycle events. Plants are required to 
submit a monitoring plan to the State prior to conducting the month 
long self assessment monitoring. Results of self assessment monitoring 
must be reported to the State. The State is required to determine, by 
reviewing the self assessment, whether the plant's current recycle 
practice should be modified to protect plant performance and provide an 
additional measure of public health protection. The State is required 
to report its determination for each plant performing a self assessment 
to EPA and briefly summarize the reason(s) supporting each 
determination.
    EPA selected the three aforementioned criteria to identify plants 
required to perform a self assessment for the following reasons. First, 
surface or GWUDI source waters may contain Cryptosporidium. Second, the 
hydraulic impact of recycle to plants typically employing more than 20 
filters to meet production requirements should be dampened because 
plant influent flow is of significantly greater magnitude than the flow 
produced by a backwash event. Third, plants that practice direct 
recycle of filter backwash and/or thickener supernatant may exceed 
their operating capacity during recycle events due to the large volume 
of these streams.
ii. Data
    Plants that recycle filter backwash and thickener supernatant, 
directly, without recycle flow equalization or treatment, may exceed 
their operating capacity during recycle events. Table IV.20 illustrates 
the magnitude by which direct recycle plants may exceed their operating 
capacity during recycle events. For purposes of the table, operating 
capacity is assumed to be either plant design flow or average flow (see 
example below). The values in the table are conservative, as they are 
likely to over predict the factor by which direct recycle plants will 
exceed operating capacity during recycle events. This conservatism is 
due to the assumed filter backwash rate of 15 gpm/ft\2\ and the assumed 
backwash duration of 15 minutes, the minimum backwash rate and duration 
recommended by the Great Lakes-Upper Mississippi River Board of State 
and Provincial Public Health and Environmental Managers (1997). Design 
and average flow values assumed for plant operating capacity were 
developed from equations presented in EPA's baseline handbook (1999g). 
For purposes of this example, plant design and average flow are assumed 
to equal State approved operating capacity to illustrate the potential 
for plants to exceed operating capacity during recycle events. Relevant 
equations and example calculations are shown below.

Example

    (1) Design to average ratios:

design flow  .25 mgd; ratio design flow : average flow = 3.2:1
design flow > .25 mgd to 1 mgd; ratio design flow : average flow = 
2.8:1
design flow > 1 mgd to 10 mgd; ration design flow : average flow = 
2.4:1
design flow > 10 mgd; ratio design flow : average flow = 2.0:1

    (2) Maximum filter size: 700 sq./ft\2\ (EPA, 1998a)
    (3) Backwash volume calculation:

Filter area (ft\2\)  x  15 gpm/ft\2\  x  15 minutes = volume of one 
backwash

    (4) Design and average capacity exceedence factors:
(Backwash flow + design (or average) flow)  design flow = 
exceedence factor

    (5) Percent Influent that is recycle:

Backwash flow  (Backwash flow + design (or average flow)) = 
percent of influent that is backwash

    (6) Design flow = State approved operating flow


                                     Table IV.20.--Impact of Direct Recycle
----------------------------------------------------------------------------------------------------------------
                                                                         Factor               Factor
                                                                         design    Percent    design    Percent
                                          Backwash                       flow is   influent   flow is   influent
                    Area of   Volume of    return                       exceeded   that is   exceeded   that is
 Design   Number      one        one     flow  (15   Design    Average     by      recycle      by      recycle
  flow      of      filter    backwash     minute     flow      flow     during      (at      during      (at
 (MGD)    filters  (sq. ft)   (gallons)   return;     (gpm)     (gpm)    recycle    design    recycle   average
                                            gpm)                           (at      flow)       (at      flow)
                                                                         design   (percent)   average  (percent)
                                                                          flow)                flow)
----------------------------------------------------------------------------------------------------------------
   .033         2         5      1,125         75         23         7       4.3        77       3.6         91
   .669         4        50     11,250        750        465       166       2.6        62       2.0         82
  2.02          6       100     22,500      1,500      1,403       584       2.1        52       1.5         72
  8.8           8       320     72,000      4,800      6,111     2,546       1.8        44       1.2         65
 14.5          10       425     95,625      6,375     10,069     5,135       1.6        39       1.1         55
 42.44         18       700    157,500     10,500     29,472    14,736       1.4        26        .86        42
 56.23         24       700    157,500     10,500     39,048    19,524       1.3        21        .77        35
----------------------------------------------------------------------------------------------------------------


[[Page 19113]]

    The purpose of Table IV.20 is to illustrate the impact direct 
recycle can have on plant hydraulic loading and the factor by which 
plant operating capacity can be exceeded during recycle events. As 
shown in Table IV.20, a plant with two filters would process influent 
at over three times its operating capacity during a recycle event. Even 
if the plant reduced or eliminated its raw water influent flow for the 
duration of the event, the remaining filter would be subject to a 
loading rate that exceeds its operating capacity, which could harm 
finished water quality.
    The amount of sedimentation basin or clarification process storage 
available during recycle events will have an impact on the hydraulic 
loading to the filters and the performance of the sedimentation or 
clarification process. The actual increase to filter loading rates may 
be less than predicted in Table IV.20 due to site-specific conditions. 
However, the potential for direct recycle plants to exceed operating 
capacity is cause for concern because oocyst removal can be 
compromised. The Agency believes 20 filters is an appropriate number 
for specifying which plants are required to perform a self assessment 
due to the results in Table IV.20 and the above considerations.
    The importance of maintaining proper plant hydraulics has been 
acknowledged, notably by Logdson (1987) who wrote, ``Both the quantity 
and quality of filtered water can be affected by plant hydraulics. 
Maximum hydraulic capacity is an obvious limitation. The adverse 
influences of rate of flow and flow patterns on water quality may not 
be so obvious, but they can be important.'' Fulton (1987) recognized 
that short circuiting can diminish the performance of settling basins, 
cause overloading of filters, and increase breakthrough of turbidity. 
Other publications (Cleasby, 1990) recognize that settled water quality 
deteriorates when the surface loading rate of sedimentation basins is 
increased. Direct recycle practice can give rise to short circuiting, 
cause plant operating capacity to be exceeded, and increase surface 
loading rates, all of which can be detrimental to Cryptosporidium 
removal.
    Direct recycle practice can abruptly increase filter loading rates, 
which has been shown to lower filter performance. Cleasby et al. (1963) 
performed experimental runs with three pilot plant filters by 
increasing the filtration rate ten, twenty-five, and fifty-percent over 
various time periods and monitoring the passage of a target material 
during the rate increase. Conclusions drawn from the experiments were:
    (1) Disturbance in filtration rate can cause filters to pass 
previously deposited material and the amount of material passed is 
dependent on the magnitude of the rate disturbance;
    (2) More rapid disturbances cause more material to be flushed 
through the filter;
    (3) The amount of material flushed through the filter is 
independent, or very nearly independent of disturbance's duration, and;
    (4) The amount of material flushed through the filter following a 
disturbance is dependent on the type of material being filtered.
    Pilot scale work was recently performed by Glasgow and Wheatley 
(1998) to investigate whether surges affect filtrate quality. Effluent 
turbidity and headloss within the filter media were monitored for two 
pilot filter columns that were surged at different magnitudes. The 
results were compared to control runs through the same pilot columns to 
determine the effect of the surge. Results indicated that surging may 
significantly affect full scale filter performance. Additional work is 
needed to confirm these results.
    Recent pilot scale work by McTigue et al. (1998) examined the 
impact of doubling the filter loading instantaneously and gradually 
(over an 80 minute period) on pilot filters that had been in operation 
for a period of time or were ``dirty.'' The experiments showed that 
Cryptosporidium removal achieved by the filters was lowered by changes 
in filtration rate regardless of whether loading rate was increased 
instantaneously or gradually. In the experiment, filter loading rates 
of 2 gpm/ft\2\ and 4 gpm/ft\2\ were doubled in six separate test runs 
to determine whether oocysts removal was affected. Results showed that 
log removal of oocysts was reduced by approximately 1.5 to 2.0 logs for 
when filter loading rates of 2 gpm/ft\2\ and 4 gpm/ft\2\ were either 
instantaneously and gradually doubled. The report states, ``These data 
clearly demonstrate that any change in filter loading rate on a filter 
that is dirty presents a risk for breakthrough of Giardia and 
Cryptosporidium to the finished water, should these organisms be 
present in the filter.'' Effluent turbidity values remained low during 
increases in filter loading rates but particle count concentrations 
immediately increased with increases in loading rate. This may indicate 
that turbidity is not a good indicator of oocyst passage by dirty 
filters during filtration rate increases.
    Results of three other pilot runs from the study showed that log 
removal of oocysts did not change when the influent oocyst 
concentration varied and all other treatment conditions were held 
constant. A four log removal of oocysts was obtained for all three runs 
despite influent oocyst concentrations of 4,610/L, 688/L, and 26/L. The 
report states, ``This finding indicates that the risk for passage of 
large numbers of cysts to the finished water is greater when a water 
treatment plant receives a highly concentrated slug of cysts at its 
intake.'' The Agency believes this is an interesting conclusion, even 
though it is based on a limited number of pilot runs. If further pilot 
and full-scale work verifies this finding, it indicates that log 
removal of oocysts does not increase as more oocysts are loaded to 
plant. Recycle of flows containing oocysts would therefore increase the 
number of oocysts present in finished water, relative to the number of 
oocysts that would occur were recycle not practiced, because plant 
treatment efficiency would not increase to remove the additional 
oocysts returned by recycle.
    In summary, the Agency is concerned that direct recycle of spent 
filter backwash, thickener supernatant, and liquids from dewatering 
process may increase the risk of oocyst occurrence in finished water 
for the following reasons:
    (1) Sampling has established that oocysts occur in finished water 
supplies (see Table II.6 of this preamble);
    (2) Data show that oocysts occur in recycle streams;
    (3) Literature indicates that hydraulically overloading the 
sedimentation process, as may happen during direct recycle events, can 
harm sedimentation performance;
    (4) Literature indicates increasing or abruptly changing filtration 
rates can lead to more material passing through filters, and;
    (5) Recent pilot scale work by McTigue et al. (1998) and Glasgow 
and Wheatley (1998) indicates that filter performance can be harmed by 
surges and changes to filtration rate.
    The Agency encourages the States to closely examine recycle self 
assessments performed by direct recycle plants to determine whether 
direct recycle poses an unacceptable risk to finished water quality and 
public health and needs to be modified due to the considerations cited 
above.
    Finally, EPA realizes that State programs may use different 
methodologies to set plant operating capacity. States may also apply 
safety factors of different magnitudes when determining operating 
capacity. The Agency does not believe it is

[[Page 19114]]

appropriate to erode any safety factor or margin of safety States 
provide when setting operating capacity. Safety factors are provided 
for a reason: to provide a margin of safety to public health protection 
efforts. The integrity and magnitude of a safety factor should be 
maintained, as it is in and of itself integral to adequate public 
health protection. The fact a safety factor is applied when plant 
operating capacity is set is not a justification, a priori, for 
allowing plants to operate above said operating capacity during recycle 
events.
    EPA also acknowledges that States may use different methodologies 
to set plant operating capacity. The Agency is confident that the State 
programs, its partners in public health protection, set plant capacity 
to provide necessary level of public health protection. The fact that 
some State programs may set plant operating capacities with different 
methodologies likely reflects geographical conditions and public 
expectations unique to certain States and sections of the country. EPA 
believes methodologies employed by the States results in establishment 
of operating capacities necessary to protect public health, meet 
regulatory requirements, and satisfy unique treatment needs and 
considerations where they exist.
iii. Proposed Requirements
    Self assessments must be performed at plants meeting all of the 
following criteria and the results of the self assessment reported to 
the State:
    (1) Use surface water or GWUDI as a source and employ conventional 
rapid granular filtration treatment;
    (2) Employ of 20 or fewer filters to meet production requirements 
during the highest production month in the 12 month period prior to 
LT1FBR's compliance date, and;
    (3) Recycle spent filter backwash or thickener supernatant directly 
to the treatment process (i.e., recycle flow is returned within the 
treatment process of a PWS without first passing the recycle flow 
through a treatment process designed to remove solids, a raw water 
storage reservoir, or some other structure with a volume equal to or 
greater than the volume of spent filter backwash water produced by one 
filter backwash event).
    Systems are required to develop and submit a recycle self 
assessment monitoring plan to the State no later than three months 
after the rule's compliance date for each plant the requirements are 
applicable to. At a minimum, the monitoring plan must identify the 
month during which monitoring will be conducted, contain a schematic 
identifying the location of raw and recycle flow monitoring devices, 
describe the type of flow monitoring devices to be used, and describe 
how data from the raw and recycle flow monitoring devices will be 
simultaneously retrieved and recorded.
    The self assessment of recycle practices shall consist of the 
following five steps:
    (1) From historical records, identify the month in the calendar 
year preceding LT1FBR's effective date with the highest water 
production.
    (2) Perform the monitoring described below in the twelve month 
period following submission of the monitoring plan to the State.
    (3) For each day of the month identified in (1), separately monitor 
source water influent flow and recycle flow before their confluence 
during one filter backwash recycle event per day, at three minute 
intervals during the duration of the event. Monitoring must be 
performed between 7:00 a.m. and 8:00 p.m. Systems that do not have a 
filter backwash recycle event every day between 7:00 am and 8:00 p.m. 
must monitor one filter backwash recycle event per day, any three days 
of the week, for each week during the month of monitoring, between 7:00 
a.m. and 8:00 p.m. Record the time filter backwash was initiated, the 
influent and recycle flow at three minute intervals during the duration 
of the event, and the time the filter backwash recycle event ended. 
Record the number of filters in use when the filter backwash recycle 
event is monitored.
    (4) Calculate the arithmetic average of all influent and recycle 
flow values taken at three minute intervals in (3). Sum the arithmetic 
average calculated for raw water influent and recycle flows. Record 
this value and the date the monitoring was performed. This value is 
referred to as event flow.
    (5) After monitoring is complete, order the event flow values in 
increasing order, from lowest to highest, and identify the monitoring 
events in which plant operating capacity is exceeded.
    Systems are required to submit a self assessment report to the 
State within one month of completing the self assessment monitoring. At 
a minimum, the report must provide the following information:
    (1) All source and recycle flow measurements taken and the dates 
they were taken. For all events monitored, report the times the filter 
backwash recycle event was initiated, the flow measurements taken at 
three minute intervals, and the time the filter backwash recycle event 
ended. Report the number of filters in use when the backwash recycle 
event is monitored.
    (2) All data and calculations performed to determine whether the 
plant exceeded its operating capacity. Report the number of event flows 
that exceed State approved operating capacity.
    (3) A plant schematic showing the origin of all recycle flows, the 
hydraulic conveyance used to transport them, and their final 
destination in the plant.
    (4) A list of all the recycle flows and the frequency at which they 
are returned to the plant.
    (5) Average and maximum backwash flow through the filters and the 
average and maximum duration of backwash events in minutes, for each 
monitoring event, and;
    (6) Typical filter run length, number of filters typically 
employed, and a written summary of how filter run length is determined 
(preset run time, headloss, turbidity level).
    EPA is proposing that the State review all self assessments 
submitted by PWSs and report to the Agency the below information as it 
applies to individual plants:
    (1) A finding that modifications to recycle practice are necessary, 
followed by a brief description of the required change and a summary of 
the reason(s) the change is required, or;
    (2) A finding that changes to recycle practice are not necessary 
and a brief description of the reason(s) this determination was made.
    The Agency also considered requiring all recycle plants without 
existing recycle flow equalization or treatment to install recycle flow 
equalization. As summarized in Table IV.21, several recommendations for 
recycle equalization and treatment have been provided. However, these 
recommendations are based on theoretical calculations and/or limited 
pilot-scale data that has not been verified by full-scale plant 
performance data. The Agency currently believes insufficient data is 
available to determine whether recycle flow equalization is necessary 
to protect finished water quality, and, if it is, the level of 
equalization required to provide protection to finished water supplies 
for a wide variety of source water qualities, treatment process types, 
and levels of treatment effectiveness. The Agency does not believe it 
is appropriate at this time to propose a national recycle flow 
equalization requirement for the following reasons:
    (1) Data on the occurrence of oocysts in recycle streams, and their 
impact to

[[Page 19115]]

finished water quality upon recycle, is very limited;
    (2) Data that establishes the magnitude of hydraulic disruption 
caused by direct recycle events for a variety of plant types, designs, 
and operational practices has not been identified; without this data, 
it is not possible to quantify how much treatment efficiency is reduced 
by the hydraulic disruption and the number of oocysts in the recycle 
flow that will enter the finished water due to the disruption. Without 
this information, it is not possible to specify the level of 
equalization necessary to control hydraulic disruption for a variety of 
plant configurations and operational practices with any degree of 
certainty and cost effectiveness, and;
    (3) A uniform, national equalization standard may not be 
appropriate because it would not allow consideration of site-specific 
factors such as plant treatment efficiency, loading capacity of 
clarification and filtration units, source water quality, and other 
site-specific factors that influence the level of equalization a plant 
may need to control recycle event induced hydraulic disruption.
    EPA believes some plants can realize substantial benefit by 
installing recycle flow equalization and will review data to determine 
the need for an equalization requirement when it becomes available. The 
Agency requests that commenters submit the following pilot or full-
scale data to assist its effort to conduct a thorough analysis of 
equalization based upon the best available science:
    (1) Data on the magnitude of hydraulic disruption caused by recycle 
events and its affect on finished water turbidity and particle count 
levels;
    (2) Data that correlate hydraulic disruption to increased oocyst 
concentration in finished water, and;
    (3) Any other data commenters believe that may be appropriate to 
analyze the need for equalization, and;
    (4) Whether the regulation should require States to specify 
modifications to recycle practice, for all plants that exceed operating 
capacity during monitoring, to ensure said plants' remain below their 
State approved operating capacity during recycle events.

                                Table IV.21--Recommended Equalization Percentages
----------------------------------------------------------------------------------------------------------------
                                                                                       Is recycle treatment
             Source of recommendation a               Equalization  Percentage             recommended?
----------------------------------------------------------------------------------------------------------------
Recommended Standards for Water Works. Great Lakes-- 10%.......................  No.
 Upper Mississippi River Board of State and
 Provincial Public Health and Environmental
 Managers. 1997. Albany: Health Education Services.
Removal of Cryptosporidium Oocysts by Water          10%.......................  Yes. Turbidity less than 5.0
 Treatment Process. Foundation for Water Research                                 NTU or residual of 10mg/L
 Limited, United Kingdom (1994).                                                  suspended solids in treated
                                                                                  recycle flow.
Recycle Stream Effects on Water Treatment.           Use equalized, continuous   Use proper waste stream
 Cornwell, D., and R. Lee. 1993. Denver: AWWARF.      recycle.                    treatment prior to recycle.
----------------------------------------------------------------------------------------------------------------
a See the reference list at the end of the preamble for complete citations.

    Finally, the Agency considered requiring conventional filtration 
plants that recycle within the treatment process to provide 
sedimentation or more advanced recycle treatment and concluded a 
national treatment requirement is inappropriate at this time due data 
deficiencies. The Agency believes the following data is necessary to 
determine whether recycle flow treatment is necessary to protect public 
health and the requisite level of treatment:
    (1) Significant amounts of additional data on the occurrence of 
oocysts for a complete range of recycle streams generated by a wide 
variety of source water qualities, treatment plant types, plant 
operational and recycle practices, and plant treatment efficiencies;
    (2) Data that correlates recycle stream oocyst occurrence to 
finished water occurrence;
    (3) Additional data on the ability of full-scale sedimentation 
basins to remove oocysts during normal operation and during recycle 
events. The Agency has identified only three full-scale studies, States 
et al. (1995), Baudin and Laine (1998), and Kelly et al. (1995), that 
allow quantification of oocyst removal by sedimentation basins. Pilot 
scale work, such as Edzwald and Kelley (1998) and Dugan et al. (1999) 
is also available, but the number of studies is not extensive. The 
removal achieved by sedimentation and other clarification processes is 
critical for determining the number of oocysts loaded to the filters, 
the likely concentration of oocysts in various recycle streams, and the 
impact recycle may have on intra-plant oocyst concentrations. Good 
oocyst removal in the clarification process will remove a large 
percentage of oocysts from recycle and source water flows before they 
reach the filters. The amount of removal provided by primary 
clarification therefore has a large influence on the level of recycle 
flow treatment that may be needed to mitigate risk to finished water 
quality. Given that data on oocyst removal by sedimentation and other 
clarification processes is very limited, the Agency does not believe it 
is possible to assess the need for recycle treatment and specify a 
minimum treatment level that is meaningful for a wide variety of plant 
types and recycle practices;
    (4) Data regarding the ability of DAF and other clarification 
processes to remove oocysts from recycle flow is very limited. This 
data is important, because the Agency anticipates plants may respond to 
any recycle treatment requirement by using DAF to treat recycle flow 
because of the advantages it provides relative to sedimentation. 
However, EPA has only identified four studies, Hall et al. (1995), 
Plummer et al. (1995), Edzwald and Kelley (1998), and Alvarez et al. 
(1999), that determined the ability of DAF to remove oocysts from 
source water. One study, by Grubb et al. (1997), addresses the ability 
of DAF to treat filter backwash waters has been identified, but 
sampling for oocyst removal was not performed, although turbidity and 
color removal were monitored and good results obtained. Additional data 
is needed to characterize the ability of DAF to remove oocysts from 
recycle flow before it can be used to meet any recycle treatment 
requirement;
    (5) Full-scale data on the ability of sedimentation and other 
clarification processes to remove oocysts from recycle streams before 
they are returned to the plant is very limited. EPA has identified two 
studies, one by Cornwell and Lee (1993) and a study by Karanis et al. 
(1998) that provide data regarding

[[Page 19116]]

sedimentation's ability to remove oocysts from recycle flows. 
Additional information is needed to establish lower and upper bounds on 
the oocyst removal sedimentation can achieve; without this data, it is 
difficult to specify a feasible level of oocyst removal in a recycle 
flow treatment requirement;
    (6) Microfiltration and ultrafiltration membranes appear to be very 
reliable at removing Cryptosporidium from source waters (Jacangelo et 
al., 1995). However, the Agency has identified limited data regarding 
the ability of membranes to effectively treat recycle flow, and 
treatment of backwash with membranes may not be appropriate at all 
locations (Thompson et al., 1995) due to incompatibility between 
membrane filter material and residual treatment chemical(s) in the 
backwash water. Additional information regarding the ability of 
microfiltration and ultrafiltration membranes to treat recycle flow is 
necessary to comprehensively evaluate their applicability, and;
    (7) EPA is not aware of a surrogate, including turbidity, particle 
counts, or any other common and easy to measure parameter, that can 
serve as an indicator of the log removal of Cryptosporidium recycle 
flow treatment units achieve. The Agency does not believe it is 
economically or technically feasible to directly monitor oocyst removal 
by treatment units. Without an accurate, easy to measure surrogate for 
Cryptosporidium removal, the Agency does not believe it is possible to 
ascertain the level of treatment recycle flow treatment units achieve 
during routine operations.
    Given the above limiting factors, the Agency does not believe it is 
prudent to establish a national recycle flow treatment requirement 
until additional data becomes available. EPA requests the following 
data be submitted:
    (1) Data regarding intra-plant and recycle stream occurrence of 
oocysts;
    (2) Information on the ability of individual treatment units of the 
primary treatment train to remove oocysts during normal, hydraulically 
challenged, and suboptimal chemical dose operations;
    (3) Data on the ability of sedimentation and other clarification 
processes to remove oocysts from a wide range of recycle streams;
    (4) Data on the compatibility of specific ultrafiltration and 
microfiltration membrane materials with residual chemicals that occur 
in recycle streams and data regarding the performance of these membrane 
materials at full and pilot scale, and;
    (5) Information on potential surrogates that can be easily measured 
and can accurately establish the log removal of oocysts removed by 
recycle flow treatment processes.
iv. Request for Comments
    EPA requests comment on the proposed requirements. The Agency also 
requests comment on the following:
    (1) What other parameters could be monitored or what other overall 
monitoring schemes could be employed to assess whether a plant is 
exceeding its operating capacity?
    (2) What data should the plant report to the State as part of its 
self assessment, beyond the monitoring data and other information 
listed above?
    (3) Is monitoring during the highest flow month appropriate? Is 
monitoring during additional months necessary? Is daily monitoring 
necessary or would less frequent monitoring during the month be 
sufficient?
    (4) Should systems be required to monitor and report turbidity 
measurements from a representative filter taken immediately preceding 
and after recycle events monitored during the self assessment to help 
characterize the impact of recycle on plant performance?
    (5) Is limiting the self assessment to plants with 20 or less 
filters appropriate? Should the number of filters be less or greater 
than 20? What is the appropriate number of filters?
    (6) Should systems be required to monitor sedimentation overflow 
rates or clarification loading rates while the recycle flow monitoring 
is performed?
    (7) EPA requests comment on criteria that may identify recycle 
plants that could receive substantial benefit from implementing recycle 
equalization or treatment as a standard practice.
    (8) What type and amount of data is required to determine whether 
recycle flow equalization would provide a benefit to finished water 
quality? What methodology could be used to determine an appropriate 
recycle flow equalization percentage, and how relevant are turbidity 
and particle counts, at various locations in a plant, to assessing an 
appropriate equalization percentage for a single plant or a plant type?

d. Requirements for Direct Filtration Plants that Recycle Using Surface 
Water or GWUDI

i. Overview and Purpose
    Today's proposal requires direct filtration plants that recycle to 
report to the State whether flow equalization or treatment is provided 
for recycle flow prior to its return to the treatment process. The 
purpose of today's proposed requirement is to assess whether the 
existing recycle practice of direct filtration plants addresses 
potential risks. The Agency believes that direct filtration plants need 
to remove oocysts from recycle flow prior to reintroducing it to the 
treatment process.
ii. Data
    Twenty-three direct filtration plants that used surface water 
responded to the FAX Survey (AWWA, 1998). In the FAX survey, plants 
could report whether they provide recycle flow equalization, 
sedimentation, or some other type of treatment. Of the respondents, 21 
reported providing treatment for the recycle flow and two plants 
reported providing only equalization. In the ICR database, there were 
23 direct filtration plants and fourteen of them recycled to the 
treatment process. All fourteen plants provide recycle treatment. It is 
not possible to determine the level of oocyst removal FAX survey and 
ICR plants achieve with available data.
    The treatment train of a direct filtration plant does not have a 
clarification process to remove Cryptosporidium before they reach the 
filters; all oocyst removal is achieved by the filters. If recycle flow 
treatment is not provided, all of the oocysts captured in the filters 
will be returned to the treatment process in the recycle flow. Because 
a primary clarification process is not present to remove recycled 
oocysts, they are caught in a closed ``loop'' from which the only exit 
is passage through the filters into the distribution system. The Agency 
believes direct filtration plants should provide solids removal 
treatment for recycle flows to limit the number of oocysts returned to 
the treatment plant.
iii. Proposed Requirements
    EPA is proposing that PWSs using direct filtration that recycle to 
the treatment process and utilize surface water or GWUDI as a source 
report data to the State that describes their current recycle practice. 
Plants should report the following information to the State:
    (1) Whether recycle flow treatment or equalization is in place;
    (2) The type of treatment provided for the recycle flow;
    (3) If equalization, sedimentation, or some type of clarification 
process is used, the following information should be provided: a) 
physical dimensions of the unit (length, width, (or circumference) 
depth,) sufficient to allow calculation of volume and the

[[Page 19117]]

type, typical dose, and frequency with which treatment chemicals are 
used;
    (4) The minimum and maximum hydraulic loading the treatment unit 
experiences, and;
    (5) Maximum backwash rate, duration, typical filter run length, and 
the number of filters at the plant.
    The State should use the above information to determine which 
plants need to modify recycle practice to provide additional public 
health protection. States are required to report to EPA whether they 
required individual direct filtration plants to modify recycle practice 
and provide a brief explanation of the reason(s) for the decision.
    The Agency also considered requiring that all direct filtration 
plants provide a specific level of treatment for the recycle flow. 
However, data necessary to determine the appropriate level of treatment 
is unavailable. Specifically, the following data is needed:
    (1) Data on the on the occurrence of oocysts in the spent filter 
backwash of direct filtration plants. Direct filtration plants 
generally use higher quality source water than conventional plants 
(AWWA, 1990) and it would be inaccurate to use spent filter backwash 
occurrence data from conventional plants to assess the level of 
treatment direct recycle plants may need;
    (2) Data regarding the ability of sedimentation and other 
clarification processes to remove oocysts from recycle flows is needed 
to determine what may be a feasible level of treatment. This data need 
was treated to a detailed discussion in the previous section of the 
preamble;
    (3) An easy to measure and accurate surrogate for oocyst removal is 
currently unavailable; without such a surrogate, it is not feasible to 
monitor the performance of recycle treatment units, and;
    (4) Data on the applicability of microfiltration and 
ultrafiltration for treating spent filter backwash produced by direct 
filtration plants. This data need was discussed in detail in the 
previous section.
    Given the lack of oocyst occurrence data for direct filtration 
recycle streams, and limited knowledge of the level of treatment 
clarification processes can achieve, the Agency does not currently 
believe it is possible to identify a treatment standard for direct 
filtration plants.
iv. Request for Comments
    EPA requests comment on the proposed requirements. The Agency also 
requests comment on the following:
    (1) Whether direct filtration plants should be required to provide 
treatment for recycle flows;
    (2) The level of treatment direct filtration plants should achieve;
    (3) Data that establishes turbidity, particle counting, or some 
other surrogate as an appropriate indicator of oocyst removal achieved 
by recycle treatment units, and;
    (4) Data on the ability of clarification processes to remove 
oocysts and criteria that can be used to determine the applicability of 
specific membrane materials for treatment of spent filter backwash 
produced by direct filtration plants.

d. Request for Additional Comment

    EPA requests comment on the following:
    (1) Should the recycle of untreated clarification sludges be 
allowed to continue, or should the Agency ban this practice? What 
affect would a ban have on the operation of specific plant types, such 
as softening plants?
    (2) Is it appropriate to apply regulatory requirements to the 
combined recycle flow rather than stipulating requirements for 
individual recycle flows? Which flows should be regulated individually 
and why?

V. State Implementation and Compliance Schedules

    This section describes the regulations and other procedures and 
policies States have to adopt, or have in place, to implement today's 
proposed rule. States must continue to meet all other conditions of 
primacy in 40 CFR part 142.
    Section 1413 of the SDWA establishes requirements that a State or 
eligible Indian tribe must meet to maintain primary enforcement 
responsibility (primacy) for its public water systems. These include: 
(1) Adopting drinking water regulations that are no less stringent than 
Federal NPDWRs in effect under sections 1412(a) and 1412(b) of the Act, 
(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 
by sections 1415 and 1416, and (5) adopting and being capable of 
implementing an adequate plan for the provision 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 section 1413 of the Act. In 
addition to adopting the basic primacy requirements, States may be 
required to adopt special primacy provisions pertaining to a specific 
regulation. These regulation-specific provisions may be necessary where 
implementation of the NPDWR involves activities beyond those in the 
generic rule. States are required by 40 CFR 142.12 to include these 
regulation-specific provisions in an application for approval of their 
program revisions. These State primacy requirements apply to today's 
proposed rule, along with the special primacy requirements discussed 
below.
    To implement today's proposed rule, States are required to adopt 
revisions to Sec. 141.2--definitions; Sec. 141.32--public notification; 
Sec. 141.70--general requirements; Sec. 141.73--filtration; 
Sec. 141.76--recycle; Sec. 141.153--content of the reports; 
Sec. 141.170--general requirements; Sec. 142.14--records kept by 
States; Sec. 142.16--special primacy requirements; and a new subpart T, 
consisting of Sec. 141.500 to Sec. 141.571.

A. Special State Primacy Requirements

    In addition to adopting drinking water regulations at least as 
stringent as the Federal regulations listed above, EPA requires that 
States adopt certain additional provisions related to this regulation 
to have their program revision application approved by EPA. This 
information advises the regulated community of State requirements and 
helps EPA in its oversight of State programs. States which require 
without exception subpart H systems (all public water systems using a 
surface water source or a ground water source under the direct 
influence of surface water) to provide filtration, need not demonstrate 
that the State program has provisions that apply to systems which do 
not provide filtration treatment. However, such States must provide the 
text of the State statutes or regulations which specifies that public 
water systems using a source water must provide filtration.
    EPA is currently developing, with stakeholders input, several 
guidance documents to aid the States and water systems in implementing 
today's proposed rule. This includes guidance for the following topics: 
Disinfection benchmarking and profiling, Turbidity, and Filter Backwash 
and Recycling. EPA will also work with States to develop a State 
implementation guidance manual.
    To ensure that the State program includes all the elements 
necessary for a complete enforcement program, the State's application 
must include the

[[Page 19118]]

following in order to obtain EPA's approval for implementing this rule:
    (1) Adoption of the promulgated LT1FBR.
    (2) Description of the procedures the State will use to determine 
the adequacy of changes in disinfection process by systems required to 
profile and benchmark under Sec. 142.16(h)(2)(ii) and how the State 
will consult with PWSs to approve modifications to disinfection 
practice.
    (3) Description of existing or adoption of appropriate rules or 
other authority under Sec. 142.16(h)(1) to require systems to 
participate in a Comprehensive Technical Assistance (CTA) activity, and 
the performance improvement phase of the Composite Correction Program 
(CCP).
    (4) Description of how the State will approve a method to calculate 
the logs of inactivation for viruses for a system that uses either 
chloramines or ozone for primary disinfection.
    (5) For filtration technologies other than conventional filtration 
treatment, direct filtration, slow sand filtration or diatomaceous 
earth filtration, a description of how the State will determine under 
Sec. 142.16(h)(2)(iii), that a public water system may use a filtration 
technology if the PWS demonstrates to the State, using pilot plant 
studies or other means, that the alternative filtration technology, in 
combination with the disinfection treatment that meets the requirements 
of Subpart T of this title, consistently achieves 99.9 percent removal 
and/or inactivation of Giardia lamblia cysts and 99.99 percent removal 
and/or inactivation of viruses, and 99 percent removal of 
Cryptosporidium oocysts; and a description of how, for the system that 
makes this demonstration, the State will set turbidity performance 
requirements that the system must meet 95 percent of the time and that 
the system may not exceed at any time a level that consistently 
achieves 99.9 percent removal and/or inactivation of Giardia lamblia 
cysts, 99.99 percent removal and/or inactivation of viruses, and 99 
percent removal of Cryptosporidium oocysts.
    (6) Description of the criteria the State will use under 
Sec. 142.16(b)(2)(vi) to determine whether public water systems 
completing self assessments under Sec. 141.76 (c) are required to 
modify recycle practice and the criteria that will be used to specify 
modifications to recycle practice.
    (7) Description of the criteria the State will use under 
Sec. 142.16(b)(2)(vii) to determine whether direct filtration systems 
reporting data under Sec. 141.76 (d) are required to change recycle 
practice and the criteria that will be used to specify changes to 
recycle practice.
    (8) The application must describe the criteria the State will use 
under Sec. 142.16(b)(2)(viii) to determine whether public water systems 
applying for a waiver to return recycle to a location other than prior 
to the point of primary coagulant addition, will be granted the waiver 
for an alternative recycle location.

B. State Recordkeeping Requirements

    Today's rule includes changes to the existing record-keeping 
provisions to implement the requirements in today's proposed rule. 
States must maintain records of the following: (1) Turbidity 
measurements must be kept for not less than one year;
    (2) disinfectant residual measurements and other parameters 
necessary to document disinfection effectiveness must be kept for not 
less than one year; (3) decisions made on a system-by-system basis and 
case-by-case basis under provisions of part 141, subpart H or subpart P 
or subpart T; (4) records of systems consulting with the State 
concerning a modification of disinfection practice (including the 
status of the consultation);
    (5) records of decisions that a system using alternative filtration 
technologies can consistently achieve a 99 percent removal of 
Cryptosporidium oocysts as well as the required levels of removal and/
or inactivation of Giardia and viruses for systems using alternative 
filtration technologies, including State-set enforceable turbidity 
limits for each system. A copy of the decision must be kept until the 
decision is reversed or revised and the State must provide a copy of 
the decision to the system, and; (6) records of systems required to do 
filter self-assessments, CPE or CCP. These decision records must be 
kept for 40 years (as currently required by Sec. 142.14 for other State 
decision records) or until a subsequent determination is made, 
whichever is shorter.

C. State Reporting Requirements

    Currently States must report to EPA information under 40 CFR 142.15 
regarding violations, variances and exemptions, enforcement actions and 
general operations of State public water supply programs. Today's 
proposal requires States to report a list of direct recycle plants 
performing self assessments, whether the State required these systems 
to modify recycle practice, and the reason(s)modifications were or were 
not required and a list of direct filtration plants performing self 
assessments, whether the State required these systems to modify recycle 
practice, and the reason(s) modifications were or were not required

D. Interim Primacy

    On April 28, 1998, EPA amended its State primacy regulations at 40 
CFR 142.12 (63 FR 23362) (EPA 1998i) 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. 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 proposed determination. However, this interim primacy 
authority is only available to a State that has primacy for every 
existing national primary drinking water regulation in effect when the 
new regulation is promulgated.
    As a result, States that have primacy for every existing NPDWR 
already in effect may obtain interim primacy for this rule, beginning 
on the date that the State submits its final application for primacy 
for this rule to EPA, or the effective date of its revised regulations, 
whichever is later. Interim primacy is available for the following 
rules:
     Stage 1 Disinfectants and Disinfection Byproducts Rule 
(December 16, 1998)(EPA,1998c)
     Interim Enhanced Surface Water Treatment Rule (EPA,1998a)
     Consumer Confidence Report Rule (EPA, 1998f)
     Variances and Exemptions Rule (EPA, 1998g)
     Drinking Water Contaminant Candidate List (EPA, 1998h)
     Revisions to State Primacy Requirements (EPA,1998i)
     Public Notification Rule (EPA, 1999i)
    In addition, a State which wishes to obtain interim primacy for 
future NPDWRs must obtain primacy for this rule. After the effective 
date of the final rule, any State that does not have primacy for this 
rule cannot obtain interim primacy for future rules.

E. Compliance Deadlines

    Section 1412(b)(10) of SDWA provides that drinking water rules 
become effective 36 months after promulgation unless the Administrator

[[Page 19119]]

determines that an earlier time is practicable. The Administrator may 
also extend the effective date by an additional 24 months if capital 
improvements are necessary. The Agency believes the three year 
effective date is appropriate for all of the provisions in today's 
notice except for those provisions that address the return of recycle 
flows. The Agency believes providing a five year compliance period for 
systems making modifications to recycle practice is appropriate and 
warranted under 1412(b)(10). To effectively modify recycle practice, 
capital improvements, such as installing additional equipment and/or 
constructing new facilities, will likely be required. Specific examples 
of potential capital improvements are installing new piping and pumps 
to convey recycle flow prior to the point of primary coagulant addition 
and constructing equalization basins or recycle flow treatment 
facilities. A limited number of systems may be able to make operational 
modifications, per the State's determination, that will effectively 
address potential risks. However, the Agency believes the great 
majority of systems required to either relocate their recycle return 
location or modify recycle practice as directed by the State will need 
to perform capital improvements. The capital improvement process is 
lengthy; systems will need to engage in preliminary planning 
activities, consult with State and local officials, develop engineering 
and construction designs, obtain financing, and construct the 
facilities. The Agency believes the widespread need that systems making 
modifications to recycle practice will have for capital improvements 
warrants the additional 24 months for compliance purposes. The Agency 
solicits comment on the appropriateness of providing an additional two 
years for compliance with the recycle provisions. EPA seeks comment on 
extending the compliance deadline an extra two years because systems 
are expected to make capital improvements to address recycle practice. 
EPA also seeks comment on a similar two year extension to comply with 
the turbidity provisions of today's proposed rule.

II. Economic Analysis

    This section summarizes the Health Risk Reduction and Cost Analysis 
in support of the Long Term 1 Enhanced Surface Water Treatment and 
Filter Backwash Rule (LT1FBR) as required by Section 1412(b)(3)(C) of 
the 1996 Amendments to the SDWA. In addition, under Executive Order 
12866, Regulatory Planning and Review, EPA must estimate the costs and 
benefits of LT1FBR in a Regulatory Impact Analysis (RIA) and submit the 
analysis to the Office of Management and Budget (OMB) in conjunction 
with publication of the proposed rule. EPA has prepared an RIA to 
comply with the requirements of this Order and the SDWA Health Risk 
Reduction and Cost Analysis (EPA, 1999h). The RIA has been published on 
the Agency's web site, and can be found at http://www.epa.gov/safewater. The RIA can also be found in the docket for this rulemaking.
    The goal of the following section is to provide an analysis of the 
costs, benefits, and other impacts of the proposed rule to support 
future decisions regarding the development of the LT1FBR.

A. Overview

    The analysis for this rule examines the costs and benefits for five 
rule provisions: filter effluent turbidity, applicability monitoring, 
disinfection benchmark profiling, uncovered finish water reservoirs, 
and recycle. Several options were considered for each provision. Costs 
were estimated for three individual turbidity options, three profiling 
options, and three applicability monitoring options. In addition, costs 
were estimated for four different recycle options. All four recycle 
options require spent filter backwash, thickener supernatant, and 
liquids from dewatering be returned to the treatment process prior to 
the point of primary coagulant addition. The extent of modifications to 
recycle practice varies among the rule options.
    The value of health benefits from the turbidity provision was 
estimated for the preferred option. The benefits from the other rule 
provisions are described qualitatively. Several non-health benefits 
from this rule were also considered by EPA but were not monetized. The 
non-health benefits of this rule include: avoided outbreak response 
costs and possibly reduced uncertainty and averting behavior costs. By 
adding the non-monetized benefits with those that are monetized, the 
overall benefits of these rule options increase beyond the dollar 
values reported.
    Additional analysis was conducted by EPA to look at the incremental 
impacts of the various rule options, impacts on households, benefits 
from reductions in co-occurring contaminants, and possible increases in 
risk from other contaminants. Finally, the Agency evaluated the 
uncertainty regarding the risk, benefits, and cost estimates.

B. Quantifiable and Non-Quantifiable Costs

    In estimating the costs of each rule option, the Agency considered 
impacts on public water systems and on States (including territories 
and EPA implementation in non-primacy States). The LT1FBR will result 
in increased costs to public water systems for improved turbidity 
treatment, applicability monitoring, disinfection benchmarking, 
covering new finished water reservoirs and modification to recycle 
practice. States will also face implementation costs. Most of the 
provisions of this rule, except the recycle provision, apply to systems 
using surface water or ground water under the direct influence of 
surface water that serve less than 10,000 people. The recycle 
provisions, however, apply to all surface water systems that recycle 
filter backwash, thickener supernatant, or liquids from dewatering.
1. Total Annual Costs
    EPA estimates that the annualized cost of the preferred 
alternatives for the proposed rule will be $97.5 million. This estimate 
includes capital costs for treatment changes and start-up labor costs 
for monitoring and reporting activities that have been annualized 
assuming a 7% discount rate and a 20-year amortization period. Other 
cost estimates reported in this section also use these same 
amortization assumptions. The estimated cost of the preferred 
alternatives also includes annual operating and maintenance costs for 
treatment changes and annual labor for turbidity monitoring activities.
    The turbidity provisions (including treatment changes, monitoring, 
and exceptions reporting) account for 70% ($68.6million annually) of 
total costs and the recycling provisions (i.e., recycle to headworks, 
self assessment, and direct filtration) account for 25% ($24.5 million 
annually) of total costs. Utility expenditures for all provisions equal 
almost 93% ($90.2 million annually) of total costs; State expenditures 
make up the other 7% ($6.7 million annually).
    To reduce the potential cost to small systems, EPA developed and 
evaluated the cost implications of several regulatory alternatives for 
four of the proposed LT1FBR provisions: individual filter turbidity 
monitoring, applicability monitoring, disinfection benchmark profiling, 
and recycle. Many of these alternatives reduce the labor burden on 
small systems relative to what it would be if the proposed rule used 
the same requirements as IESWTR. The total national costs previously

[[Page 19120]]

discussed only included the costs of the preferred alternatives. The 
following section will describe the cost estimates for each provision 
and discuss the cost of other alternatives that were considered.
2. Annual Costs of Rule Provisions
    The national estimate of annual utility costs for the proposed 
turbidity provisions is based on estimates of system-level costs for 
the various provisions of the rule and estimates of the number of 
systems expected to incur each type of cost. The following paragraphs 
describe the cost estimates for each of the rule provisions.
Turbidity Provision Costs
    The turbidity provisions are estimated to cost $69.0 million 
annually. This cost is associated with three primary activities that 
result from this provision: treatment changes, monitoring, and 
exceptions reporting.
    The treatment costs associated with meeting the revised turbidity 
standard of 0.3 NTU or less are the main costs associated with the 
turbidity provision. EPA estimates that 2,406 systems will modify their 
turbidity treatment in response to this rule. These costs are estimated 
to be $52.2 million annually. O&M expenditures account for 59% of 
annual costs and the remain 41% percent is annualized capital costs.
    In addition to the turbidity treatment costs, turbidity monitoring 
costs apply to all small surface water or GWUDI systems using 
conventional or direct filtration methods. There are an estimated 5,896 
systems that fall under this criteria. EPA estimated the costs to 
utilities for three turbidity monitoring alternatives. Alternative B, 
the preferred alternative, excludes the exceptions report for an 
individual filter exceeding 0.5 NTU in two consecutive measurements, 
enabling systems to shift from daily to weekly analysis and review of 
the monitoring data. The annualized individual filter turbidity cost to 
public water systems for this preferred option is approximately $10.1 
million. In contrast, under the IESWTR monitoring requirements of 
Alternative A, small systems would expend $63.3 million annually for 
turbidity monitoring. Alternative C, which only requires monthly 
analysis is estimated to cost $5.6 million annually. The total state 
turbidity start-up and monitoring annual costs are $4.98 million 
annually and is assumed to be the same for all of the three 
alternatives.
    In addition to the turbidity treatment and monitoring costs, 
individual filter turbidity exceptions are estimated to cost utilities 
$120 thousand annually for the preferred option. State costs will be 
approximately $1.17 million. This cost includes the annual exception 
reports and annual individual filter self assessment costs. Costs are 
slightly higher for the other two alternative individual filter 
turbidity monitoring options because they result in increased number of 
exception reports.
Disinfection Benchmarking Costs
    Disinfection benchmarking involves three components: profiling, 
applicability monitoring, and benchmarking. Four options were costed 
for applicability monitoring. Alternative 3, which uses the critical 
monitoring period, is estimated to cost less than $0.4 million 
annually. This is substantially lower than the $6.0 million estimated 
for Alternative 1, which has the same requirements as IESWTR. 
Alternative 2 requires sampling once per quarter for 4 quarters for 
systems serving 501-10,000, but allows systems under 500 to sample once 
during the critical monitoring period. This option has an annualized 
cost of $1.1 million. The preferred option, Alternative 4, makes it 
optional to sample during the critical monitoring period and is 
estimated to cost $0.04 million annualized.
    Three options were considered for disinfection profiling and 
benchmarking. They differed in the frequency and duration of data 
collection. The preferred alternative, Alternative 2, requires weekly 
monitoring for one year and is estimated to have an annualized cost of 
$0.8 million. In comparison, Alternative 1 which requires daily data 
collection for one year, has an annualized cost of approximately $1.3 
million. The final option, Alternative 3, requires daily monitoring for 
1 month and has an estimated annualized cost of $0.5 million.
    State disinfection benchmarking annualized costs are estimated to 
be $0.4 million. This estimate includes start-up, compliance tracking/
recordkeeping, and benchmark related costs.
Covered Finished Water Reservoir Provision Costs
    The proposed LT1FBR requires that new systems cover all finished 
water reservoirs, holding tanks, or other storage facilities for 
finished water. Historical construction rates suggest that new 
reservoirs over the next 20 years will roughly equal to five percent of 
the existing number of systems. Assuming then that 580 new uncovered 
finished water reservoirs would be built in the next 20 years, total 
annual costs, including annualized capital costs and one year of O&M 
costs are expected to be $2.6 million for this provision using a 7% 
discount rate. This estimate is calculated from a projected 
construction rate of new reservoirs and unit cost assumptions for 
covering new finished water reservoirs.
Recycle Provision Cost
    EPA considered four different regulatory options for recycle. Each 
of the four options requires spent filter backwash, thickener 
supernatant, and liquids from dewatering be returned prior to the point 
of primary coagulant addition. Alternative 1, is estimated to result in 
an annualized cost of $16.7 million. Of the total costs of this 
alternative, State start-up and review costs for this alternative are 
only $20 to $30 thousand annually.
    Alternative 2, the preferred option, further requires that 
conventional rapid granular filtration plants using surface water or 
GWUDI perform a self assessment if they recycle spent filter backwash 
and thickener supernatant, employ 20 or less filters, and practice 
direct recycle (treatment for the recycle flow or equalization in a 
basin that has a volume equal to the volume of spent filter backwash 
produced by a single filter backwash event is not provided). The 
results of the self assessment are reported to the State, and it 
specifies whether modifications to recycle practice are necessary. PWSs 
are required to implement the modification specified by the State. 
Under Alternative 2, direct filtration plants are required to submit 
data to the State on current recycle practice, and the State specifies 
whether changes to recycle practice are required. The total annualized 
cost of Alternative 2 is $17.4 to $24.5 million. $0.4 to $5.9 million 
of the total annualized cost is for the direct recycle component, $0.1 
to $1.7 million is for the direct filtration component, and the 
remaining cost is for the requirement to return recycle prior to the 
point of primary coagulant addition. Of the total costs of this 
alternative, State start-up, review, and self assessment costs for this 
alternative is only $115 thousand annually.
    Alternative 3 contain the same requirements for direct filtration 
plants and also requires the three recycle flows mentioned above be 
returned prior to the point of primary coagulant addition. Direct 
recycle plants are required to install equalization basins with a 
volume equal to or greater than the volume produced by two filter 
backwash events. The annualized cost of Alternative 3 is $55.0 to $56.7 
million. Of this range, $38.1 million of

[[Page 19121]]

the annualized cost is directly associated with requiring direct 
recycle plants to install equalization, and $0.1 to $1.7 million is 
associated with the direct filtration component. State start-up and 
self assessment costs for this alternative is $95 thousand annually.
    Alternative 4 requires the three recycle flows mentioned above be 
returned prior to the point of primary coagulant addition and also 
requires that all systems that recycle (conventional and direct 
systems) install sedimentation basins for recycle flow treatment. 
Systems may also install recycle flow treatment technologies that 
provide treatment capability equivalent or superior to sedimentation. 
For cost estimation purposes, sedimentation basins with tube settlers 
and polymer addition where used. The Agency approximated the annualized 
costs of this option to be $151.8 million. The sedimentation basin 
treatment requirement for conventional and direct filtration plants is 
88% ($133.3 million) of the total annualized cost of Alternative 4. 
State start-up and self assessment costs for this alternative is $100 
thousand annually.
3. Non-Quantifiable Costs
    Although EPA has estimated the cost of all the rule's components on 
drinking water systems and States, there are some costs that the Agency 
did not quantify. These non-quantifiable costs result from 
uncertainties surrounding rule assumptions and from modeling 
assumptions. For example, EPA did not estimate a cost for systems to 
acquire land if they needed to build a treatment facility or 
significantly expand their current facility. This was not costed 
because many systems will be able to construct new treatment facilities 
on land already owned by the utility. In addition, if the cost of land 
was prohibitive, a system may choose another lower cost alternative 
such as connecting to another source. A cost for systems choosing this 
alternative is unquantified in our analysis.

C. Quantifiable and Non-Quantifiable Health Benefits

    The primary benefits of today's proposed rule come from reductions 
in the risks of microbial illness from drinking water. In particular, 
LT1FBR focuses on reducing the risk associated with disinfection 
resistant pathogens, such as Cryptosporidium. Exposure to other 
pathogenic protozoa, such as Giardia, or other waterborne bacteria, 
viral pathogens, and other emerging pathogens are likely to be reduced 
by the provisions of this rule as well but are not quantified. In 
addition, LT1FBR produces nonquantifiable benefits associated with the 
risk reductions that result from the recycle provision, uncovered 
reservoirs provision, including Cryptosporidium in GWUDI definition, 
and including Cryptosporidium in watershed requirements for unfiltered 
systems.
1. Quantified Health Benefits
a. Turbidity Provisions
    The quantification of benefits from this rule is focused solely on 
reductions in the risk of cryptosporidiosis. Cryptosporidiosis is an 
infection caused by Cryptosporidium which is an acute, self-limiting 
illness lasting 7 to 14 days with symptoms that include diarrhea, 
abdominal cramping, nausea, vomiting and fever (Juranek, 1995). The 
cost of illness avoided of cryptosporidiosis is estimated to have a 
mean of $2,016 (Harrington et al., 1985; USEPA 1999h)
    The benefits of the turbidity provisions of LT1FBR come from 
improvements in filtration performance at water systems. The benefits 
analysis attempts to take into account some of the uncertainties in the 
analysis by estimating benefits under two different current treatment 
and three improved removal assumptions. The benefits analysis also used 
Monte Carlo simulations to derive a distribution of estimates, rather 
than a single point estimate.
    The benefits analysis focused on estimating changes in incidence of 
cryptosporidiosis that would result from the rule. The analysis 
included estimating the baseline (pre-LT1FBR) level of exposure from 
Cryptosporidium in drinking water, reductions in such exposure 
resulting from treatment changes to comply with the LT1FBR, and 
resultant reductions of risk.
    Baseline levels of Cryptosporidium in finished water were estimated 
by assuming national source water occurrence distribution (based on 
data by LeChevallier and Norton, 1995) and a national distribution of 
Cryptosporidium removal by treatment.
    In the LT1FBR RIA, the following two assumptions were made 
regarding the current Cryptosporidium oocyst performance to estimate 
finished water Cryptosporidium concentrations. First, based on 
treatment removal efficiency data presented in the 1997 IEWSTR, EPA 
assumed a national distribution of physical removal efficiencies with a 
mean of 2.0 logs and a standard deviation of  0.63 logs. 
Because the finished water concentrations of oocysts represent the 
baseline against which improved removal from the LT1FBR is compared, 
variations in the log removal assumption could have considerable impact 
on the risk assessment. Second, to evaluate the impact of the removal 
assumptions on the baseline and resulting improvements, an alternative 
mean log removal/inactivation assumption of 2.5 logs and a standard 
deviation of  0.63 logs was also used to calculate finished 
water concentrations of Cryptosporidium.
    For each of the two baseline assumptions, EPA assumed that a 
certain number of plants would show low, mid or high improved removal, 
depending upon factors such as water matrix conditions, filtered water 
turbidity effluent levels, and coagulant treatment conditions. As a 
result, the RIA considers six scenarios that encompass the range of 
endemic health damages avoided based on the rule.
    The finished water Cryptosporidium distributions that would result 
from additional log removal with the turbidity provisions, were derived 
assuming that additional log removal was dependent on current removal, 
i.e., that sites currently operating at the highest filtered water 
turbidity levels would show the largest improvements or high improved 
removal assumption (e.g., plants now failing to meet a 0.4 NTU limit 
would show greater removal improvements than plants now meeting a 0.3 
NTU limit).
    Table VI.1 indicates estimated annual benefits associated with 
implementing the LT1FBR. The benefits analysis quantitatively examines 
endemic health damages avoided based on the LT1FBR for each of the six 
scenarios mentioned above. For each of these scenarios, EPA calculated 
the mean of the distribution of the number of illnesses avoided. The 
10th and 90th percentiles imply that there is a 10 percent chance that 
the estimated value could be as low as the 10th percentile and there is 
a 10 percent chance that the estimated value could be as high as the 
90th percentile. EPA's Office of Water has evaluated drinking water 
consumption data from USDA's 1994-1996 Continuing Survey of Food 
Intakes by Individuals (CSFII) Study. EPA's analysis of the CSFII Study 
resulted in a daily water ingestion lognormally distributed with a mean 
of 1.2 liters per person (EPA, 2000a). The risk and benefit analysis 
contained within the RIA reflects this distribution.

[[Page 19122]]



             Table VI.1.--Number and Value of Illnesses Avoided Annually From Turbidity Provisions a
                                          [Dollar amounts in billions]
----------------------------------------------------------------------------------------------------------------
                                                                                 Daily Drinking Water Ingestion
                                                                                and Baseline Cryptosporidium Log-
                                                                                 Removal Assumptions (Mean = 1.2
                        Improved Log-Removal Assumption                                Liters per person)
                                                                               ---------------------------------
                                                                                    2.0 log          2.5 log
----------------------------------------------------------------------------------------------------------------
Illnesses Avoided with Low Improved Cryptosporidium Removal Assumption:
    Mean......................................................................         62,800.0         22,800.0
    10th Percentile...........................................................              0.0              0.0
    90th Percentile...........................................................        152,000.0         43,900.0
COI Avoided with Low Improved Cryptosporidium Removal Assumption:
    Mean......................................................................           $150.3            $53.9
    10th Percentile...........................................................             $0.0             $0.0
    90th Percentile...........................................................           $288.2            $81.4
Illnesses Avoided with Mid Improved Cryptosporidium Removal Assumption:
    Mean......................................................................         77,500.0         27,900.0
    10th Percentile...........................................................              0.0              .00
    90th Percentile...........................................................        184,000.0         52,900.0
COI Avoided with Mid Improved Cryptosporidium Removal Assumption:
    Mean......................................................................           $185.3            $66.2
    10th Percentile...........................................................             $0.0             $0.0
    90th Percentile...........................................................           $350.9            $98.8
Illnesses Avoided with High Improved Cryptosporidium Removal Assumption:
    Mean......................................................................         83,600.0         30,000.0
    10th Percentile...........................................................              0.0              0.0
    90th Percentile...........................................................        196,000.0         56,500.0
COI Avoided with High Improved Cryptosporidium Removal Assumption:
    Mean......................................................................           $199.5            $71.1
    10th Percentile...........................................................             $0.0             $0.0
    90th Percentile...........................................................           $376.7          $105.8
----------------------------------------------------------------------------------------------------------------
a All values presented are in January 1999 dollars.

    According to the RIA performed for the LT1FBR published today, the 
rule is estimated to reduce the mean annual number of illnesses caused 
by Cryptosporidium in water systems with improved filtration 
performance by 22,800 to 83,600 cases depending upon which of the six 
baseline and improved Cryptosporidium removal assumptions was used, and 
assuming the 1.2 liter drinking water consumption distribution. Based 
on these values, the mean estimated annual benefits of reducing the 
illnesses ranges from $54 million to $200 million per year. The RIA 
also indicated that the rule could result in a mean reduction of 3 to 
10 fatalities each year, depending upon the varied baseline and 
improved removal assumptions. Using a mean value of $5.7 million per 
statistical life saved, reducing these fatalities could produce 
benefits in the range of $16.0 million to $60 million.
    Combining the value of illnesses and mortalities avoided, the total 
benefits range from $70 million to $260 million assuming a 1.2 liter 
drinking water consumption distribution.
b. Sensitivity Analysis for Recycle Provisions
    Available literature research demonstrates that increased hydraulic 
loading or disruptive hydraulic currents, such as may be experienced 
when plants exceed State-approved operating capacity or when recycle is 
returned directly into the sedimentation basin, can disrupt filter 
(Cleasby, 1963; Glasgow and Wheatley, 1998; McTigue et al, 1998) and 
sedimentation (Fulton, 1987; Logsdon, 1987; Cleasby, 1990) performance. 
However, the literature does not quantify the extent to which 
performance can be lowered and, more specifically, does not quantify 
the log reduction in Cryptosporidium removal that may be experienced 
during direct recycle events.
    In the absence of quantified log reduction data, the Agency 
performed a sensitivity analysis to estimate a range of potential 
benefit provided by the recycle provisions. The analysis assumes a 
baseline Cryptosporidium log removal value of 2.0. The analysis 
estimates the effect of recycle by reducing the average baseline log 
removal by a range of values (reduction ranged from 0.05 to 0.50 log) 
to account for the reduction in removal performance plants may 
experience if they exceed State-approved operating capacity or return 
recycle to the sedimentation basin. The installation of equalization to 
eliminate exceedence of State-approved operating capacity or moving the 
recycle return location from the sedimentation basin to prior to the 
point of primary coagulant addition will result in the health benefit. 
The benefit estimate is conservative, because it does not account for 
the fact that recycle returns additional oocysts to the plant.
    Benefits are estimated by assuming that the installation of 
equalization or moving the recycle return point prior to the point of 
primary coagulant addition will return the plant to the baseline 
Cryptosporidium removal of 2.0 log. The difference between the number 
of illnesses that result from the baseline situation and the reduced 
performance is used to calculate the monetary benefit. The benefit is 
compared to the cost of returning recycle prior to the point of primary 
coagulant additional and the cost of installing equalization for two 
service populations. Service populations of 1,900 persons, which 
represents a plant serving fewer than 10,000 people, and a service 
population of 25,108, which represents a plant serving greater than 
10,000 people, are used. Results are summarized in Tables IV.2 and IV.3 
below.

[[Page 19123]]



                              Table IV.2.--Benefit for Service Population of 1,900
----------------------------------------------------------------------------------------------------------------
                                                                Benefit a for                       Cost a of
                    Log removal reduction                       population of      Cost a of        installing
                                                                    1,900        moving recycle    equalization
-------------------------------------------------------------------------------------return---------------------
0.05.........................................................           $1,400           $5,200          $25,200
0.50.........................................................           30,700            5,200          25,200
----------------------------------------------------------------------------------------------------------------
a Cost and benefit are annualized with a 7% capital cost over 20 years.


                           Table IV.3.--Benefit Range for Service Population of 25,108
----------------------------------------------------------------------------------------------------------------
                                                                Benefit a for                       Cost a of
                    Log removal reduction                       population of      Cost a of        installing
                                                                    25,108       moving recycle    rqualization
-------------------------------------------------------------------------------------return---------------------
0.05.........................................................          $18,700          $18,700          $57,200
0.50.........................................................          405,800           18,700          57,200
----------------------------------------------------------------------------------------------------------------
a Cost and benefit are annualized with a 7% capital cost over 20 years.

    Although literature research does not quantify the log reduction 
caused by specific recycle practices, the results of the sensitivity 
analysis show that the benefit a plant serving 25,108 people would 
realize by improving its baseline performance to 2.0 logs would range 
from $18,700 to $405,800. $27,256 Benefits would range from $1,400 to 
$30,700 for a plant serving 1,900. This benefit range supports the 
Agency's determination that unquantified benefits will justify costs. 
The determination is discussed in the Benefit Cost Determination 
section.
2. Non-Quantified Health and Non-Health Related Benefits
a. Recycle Provisions
    The benefits associated with the filter backwash provision are 
unquantified because of data limitations. Specifically, there is a lack 
of treatment performance data to accurately model the oocysts removal 
achieved by individual full-scale treatment processes and the impact 
recycle may have on treatment unit performance and finished water 
quality. Additional data on the ability of unit processes 
(sedimentation, DAF, contact clarification, filtration) to remove 
oocysts from source and recycle flows, the extent to which recycle may 
generate hydraulic surge within plants and lower the performance of 
individual treatment processes, data on the potential for recycle to 
threaten the integrity of chemical treatment, and additional 
information on the occurrence of oocysts in recycle streams are all 
needed before an impact model can be calibrated and used as a 
predictive tool.
    However, available data demonstrate that oocysts occur in recycle 
streams, often at concentrations higher than found in source water, and 
returning recycle streams to the plant will increase intra-plant oocyst 
concentrations. Data also shows that oocysts frequently occur in the 
finished water of treatment plants that are not operating under 
stressed conditions. Engineering literature also shows that proper 
coagulation and the maintenance of balanced hydraulic conditions within 
the plant (i.e., not exceeding State approved sedimentation/
clarification and filtration operating rates) are important to protect 
the integrity of the entire treatment process. Some recycle practices, 
such as direct recycle, can potentially upset coagulation and the 
proper hydraulic operation of sedimentation/clarification and 
filtration processes. The benefits of the recycle provisions are 
derived from protecting the coagulation process and the hydraulic 
performance of sedimentation/clarification and filtration processes. 
Today's recycle provisions reduce the risk posed by recycle and 
provided additional public health protection in the following ways:
    (1) Returning spent filter backwash, thickener supernatant, and 
liquids from dewatering into, or downstream of, the point of primary 
coagulant addition may disrupt treatment chemistry by introducing 
residual coagulant or other treatment chemicals to the process stream. 
The wide variation in plant influent flow can also result in chemical 
over-or under-dosing if chemical dosage is not adjusted to account for 
flow variation. Returning the above flows prior to the point of primary 
coagulant addition will help protect the integrity of coagulation and 
protect the performance of downstream unit processes, such as 
clarification and filtration, that require proper coagulation be 
conducted to maintain proper performance. This will provide an 
additional measure of public health protection.
    (2) The direct recycle of spent filter backwash without first 
providing treatment, equalization, or some form of hydraulic detention 
for the flow, may cause plants to exceed State-approved operating 
capacity during recycle events. This may lead to lower overall oocyst 
removal performance due to the hydraulic overload unit processes (i.e., 
clarification and filtration) experience and increase finished water 
oocyst concentrations. The self assessment provision in today's rule 
will help the States identify direct recycle systems that may 
experience this problem so modifications to recycle practice can be 
made to protect public health.
    (3) Direct filtration plants do not employ a sedimentation basin in 
their primary treatment process to remove solids and oocysts; all 
oocyst removal is achieved by the filters. If treatment for the recycle 
flow is not provided prior to its return to the plant, all of the 
oocysts captured by a filter during a filter run will be returned to 
the plant and again loaded to the filters. This may lead to ever 
increasing levels of oocysts being applied to the filters and could 
increase the concentration of oocysts in finished water. Today's 
provision for direct recycle systems will help States identify those 
systems that are not obtaining sufficient oocyst removal from the 
recycle flow. Public health protection will be increased when systems 
implement modifications to recycle practice specified by the State.
    The goal of the recycle provisions is to reduce the potential for 
oocysts getting into the finished water and causing cases of 
cryptosporidiosis. Other disinfection resistant pathogens may also be 
removed more efficiently due to implementation of these provisions.

[[Page 19124]]

b. Issues Associated With Unquantified Benefits
    The monetized benefits from filter performance improvements are 
likely not to fully capture all the benefits of the turbidity 
provisions. EPA monetized the benefits from reductions in 
cryptosporidiosis by using cost-of-illness (COI) estimates. This may 
underestimate the actual benefits of these reductions because COI 
estimates do not include pain and suffering. In general, the COI 
approach is considered a lower bound estimate of willingness-to-pay 
(WTP) to avoid illnesses. EPA requests comment on the use of an 
appropriate WTP study to calculate the benefits of this rule.
    Several non-health benefits from this rule were also considered by 
EPA but were not monetized. The non-health benefits of this rule 
include avoided outbreak response costs and possibly reduced 
uncertainty and averting behavior costs. By adding the non-monetized 
benefits with those that are monetized, the overall benefits of this 
rule would increase beyond the dollar values reported.

D. Incremental Costs and Benefits

    EPA evaluated the incremental or marginal costs of today's proposed 
turbidity option by analyzing various turbidity limits, 0.3 NTU, 0.2 
NTU, and 0.1 NTU. For each turbidity limit, EPA developed assumptions 
about which process changes systems might implement to meet the 
turbidity level and how many systems would adopt each change. The 
comparison of total compliance cost estimates show that costs are 
expected to increase significantly across turbidity limits. The total 
cost of a 0.1 NTU limit, $404.6 million, is almost eight times higher 
than the cost of the 0.3 NTU limit, which is $52.2 million. Similarly, 
the total cost of the 0.2 NTU limit, $134.1 million, is more than twice 
as great as the 0.3 NTU cost.
    Analytical limitations in the estimation of the benefits of LT1FBR 
prevent the Agency from quantitatively describing the incremental 
benefits of alternatives. The Agency requests comment on how to analyze 
and the appropriateness of analyzing incremental benefits and costs for 
treatment techniques that address microbial contaminants.

E. Impacts on Households

    The cost impact of LT1FBR at the household level was also assessed. 
Household costs are a way to represent water system treatment costs as 
costs to the system's customers. As expected, costs per household 
increase as system size decreases. Costs to households are higher for 
households served by smaller systems than larger systems for two 
reasons. First, smaller systems serve far fewer households than larger 
systems, and consequently, each household must bear a greater 
percentage share of capital and O&M costs. Second, filter backwash 
recycling may pose a greater risk because the flow of water from filter 
backwash recycling is a larger portion of the total water flow in 
smaller systems. This greater risk potential in small systems makes it 
more likely that some form of recycle treatment might be needed.
    The average (mean) annual cost for the turbidity, benchmarking, and 
covered finished water provision per household is $8.66. For almost 86 
percent of the 6.6 million households affected by these provisions, the 
per-household costs are $10 per year or less, and costs of $120 per 
year (i.e., $10 per month) or less for approximately 99 percent of the 
households. Costs exceeding $500 per household occur only for the 
smallest size category, and the number of affected households represent 
about 34 of the smallest systems. The highest per-household cost 
estimate is $2,177. This extreme estimate, however, is an artifact of 
the way the system cost distribution was generated. It is unlikely that 
any small system will incur annual costs of this magnitude because less 
costly options are available.
    The average household cost for the recycle provisions is $1.80 per 
year for households that are served by systems that recycle. The cost 
per household is less than $10 per year for almost 99% of 12.9 million 
households potentially affected by the proposed rule. The cost per 
household exceeds $120 per year for less than 1800 households and it 
exceeds $500 per year for approximately 100 households. The maximum 
cost of $1,238 per year would only be incurred if a direct filtration 
system that serves less than 100 customers installed a sedimentation 
basin for backwash treatment.
    There are approximately 1.5 million households served by small 
drinking water systems that may be affected by the recycling provisions 
in addition to the turbidity, benchmarking, and covered finished water 
provisions. The expected aggregate annual cost to these households can 
be approximated by the sum of the expected cost for each distribution, 
which is $10.45 per year.
    The assumptions and structure of this analysis tend to overestimate 
the highest costs. To face the highest household costs, a system would 
have to implement all, or almost all, of the treatment activities. 
These systems, however, might seek less costly alternatives, such as 
connecting into a larger regional water system.

F. Benefits From the Reduction of Co-Occurring Contaminants

    If a system chooses to install treatment, it may choose a 
technology that would also address other drinking water contaminants. 
For example, some membrane technologies installed to remove bacteria or 
viruses can reduce or eliminate many other drinking water contaminants 
including arsenic.
    The technologies used to reduce individual filter turbidities have 
the potential to reduce concentrations of other pollutants as well. 
Reduction in turbidity that result from today's proposed rule are aimed 
at reducing Cryptosporidium by physical removal. It is reasonable to 
assume that similar microbial contaminants will also be reduced as a 
result of improvements in turbidity removal. Health risks from Giardia 
lamblia and emerging disinfection resistant pathogens, such as 
microsporidia, Toxoplasma, and Cyclospora, are also likely to be 
reduced as a result of improvements in turbidity removal and recycle 
practices. The frequency and extent that LT1FBR would reduce risk from 
other contaminants has not been quantitatively evaluated because of the 
Agency's lack of data on the removal efficiencies of various 
technologies for emerging pathogens and the lack of co-occurrence data 
for microbial pathogens and other contaminants from drink water 
systems.

G. Risk Increases From Other Contaminants

    It is unlikely that LT1FBR will result in any increased risk from 
other contaminants. Improvements in plant turbidity performance will 
not result in any increases in risk. In addition, the benchmarking and 
profiling provisions were designed to minimize the potential reductions 
in microbial disinfection in order to lower disinfection byproduct 
levels to comply with the Stage 1 Disinfection Byproducts Rule. 
Furthermore, the filter backwash provision does not potentially 
increase the risk from other contaminants.

H. Other Factors: Uncertainty in Risk, Benefits, and Cost Estimates

    There is uncertainty in the baseline number of systems, the risk 
calculation, and the cost estimates. Many of these uncertainties are 
discussed in more detail in previous sections of today's proposal.

[[Page 19125]]

    First, the baseline number of systems is uncertain because of data 
limitation problems in SDWIS. For example, some systems use both ground 
and surface water but because of other regulatory requirements are 
labeled in SDWIS as surface water. Therefore, EPA does not have a 
reliable estimate of how many of these mixed systems exist. The SDWIS 
data on non-community water systems does not have a consistent 
reporting convention for population served. Some states may report the 
population served over the course of a year, while others may report 
the population served on an average day. Also, SDWIS does not require 
states to provide information on current filtration practices and, in 
some cases, it may overestimate the daily population served. For 
example, a park may report the population served yearly instead of 
daily. EPA is looking at new approaches to address these issues and 
both are discussed below in request for comment.
    Second, there are several important sources of uncertainty that 
enter the benefits assessment. They include the following:
     Occurrence of Cryptosporidium oocysts in source waters
     Baseline occurrence of Cryptosporidium oocysts in finished 
waters
     Reduction of Cryptosporidium oocysts due to improved 
treatment, including filtration and disinfection
     Viability of Cryptosporidium oocysts after treatment
     Infectivity of Cryptosporidium
     Incidence of infections (including impact of under 
reporting)
     Characterization of the risk Willingness-to-pay to reduce 
risk and avoid costs.
     The baseline water system treatment efficiency for the 
removal of Cryptosporidium is uncertain. Turbidity measurements have 
been used as a means of estimating removal treatment efficiency (i.e. 
log removal). In addition to the baseline treatment efficiency 
estimates, improvements in treatment efficiency for Cryptosporidium 
removal that result from this rule are uncertain.
    The benefit analysis incorporates all of the uncertainties 
associated with the benefits assessment in either the Monte Carlo 
simulations or the assumption of two baselines--2.0 log removal and 2.5 
log removal. The results in table VI.1 show that benefits are more 
sensitive to the baseline log removal assumptions than the range of low 
to high improved removal assumptions. Third, some costs of today's 
proposed rule are uncertain because of the diverse nature of the 
modifications that may be made to address turbidity limits. Cost 
analysis uncertainties are primarily caused by assumptions made about 
how many systems will be affected by various provisions and how they 
will likely respond. Capital and O&M expenditures account for a 
majority of total costs. EPA derived these costs for a ``model'' system 
in each size category using engineering models, best professional 
judgement, and existing cost and technology documents. Costs for 
systems affected by the proposed rule could be higher or lower, which 
would affect total costs. Also, the filter backwash provision's 
flexibility for States to assess plants' need to modify recycle 
practices leads to some uncertainty in the estimates of how many plants 
will have to potentially install some form of recycle equalization or 
treatment. These uncertainties could either under or overestimate the 
costs of the rule.

I. Benefit Cost Determination

    The Agency has determined that the benefits of the LT1FBR justify 
the costs. EPA made this determination for both the LT1 and the FBR 
portions of the rule separately as described below.
    The Agency has determined that the benefits of the LT1 provisions 
justify their costs on a quantitative basis. The LT1 provisions include 
enhanced filtration, disinfection benchmarking and other non-recycle 
related provisions. The quantified benefits of $70 million to $259.4 
million annually exceed the costs of $73 million at the seven percent 
cost of capital over a substantial portion of the range of benefits. In 
addition, the non-quantified benefits include avoided outbreak response 
costs and possibly reduced uncertainty and averting behavior costs.
    The Agency has determined that the benefits of the recycle 
provisions (FBR) justify their cost on a qualitative basis. The recycle 
provisions will reduce the potential for certain recycle practices to 
lower or upset treatment plant performance during recycle events; the 
provisions will therefore help prevent Cryptosporidium oocysts from 
entering finished drinking water supplies and will increase public 
health protection.
    The Agency strongly believes that returning Cryptosporidium to the 
treatment process in recycle flows, if performed improperly, can create 
additional public health risk. The Agency holds this belief for three 
reasons. First, returning recycle flow directly to the plant, without 
equalization or treatment, can cause large variations in the influent 
flow magnitude and influent water quality. If chemical dosing is not 
adjusted to reflect this, less than optimal chemical dosing can occur, 
which may lower the performance of sedimentation and filtration. 
Returning recycle flows prior to the point of primary coagulant 
addition will help diminish the risk of less than optimal chemical 
dosing and diminished sedimentation and filtration performance. Second, 
exceeding State-approved operating capacity, which is likely to occur 
if recycle equalization or treatment is not in place, can hydraulically 
overload plants and diminish the ability of individual unit processes 
to remove Cryptosporidium. Exceeding approved operating capacity 
violates fundamental engineering principles and water treatment 
objectives. States set limits on plant operating capacity and loading 
rates for individual unit processes to ensure treatment plants and 
individual treatment processes are operated to within their 
capabilities so that necessary levels of public health protection are 
provided. Third, returning recycle flows directly into flocculation or 
sedimentation basins, which can generate disruptive hydraulic currents, 
may lower the performance of these units and increase the risk of 
Cryptosporidium in finished water supplies.
    The recycle provisions in today's proposal are designed to address 
those recycle practices that are inconsistent with fundamental 
engineering and water treatment principles. The objective of the 
provisions is to eliminate practices that are counter to common sense, 
sound engineering judgement, and that create additional and preventable 
risk to public health. EPA believes the public health protection 
benefit provided by the recycle provisions justifies their cost because 
they are based upon sound engineering principles and are designed to 
eliminate recycle practices that are very likely to create additional 
public health risk.

J. Request for Comment

    Pursuant to Section 3142(b)(3)(C), the Agency requests comment on 
all aspects of the rule's economic impact analysis. Specifically, EPA 
seeks input into the following two issues.
NTNC and TNC Flow Estimates
    As part of the total cost estimates for LT1FBR, EPA estimated the 
cost of the rule on NTNC and TNC water systems by using flow models. 
However, these flow models were developed to estimate flows only for 
CWS and they may not accurately represent the much smaller flows 
generally found in NTNC and TNC systems. The effect of the overestimate 
in flow would be to inflate

[[Page 19126]]

the cost of the rule for these systems. The Agency requests comment on 
an alternative flow analysis for NTNC and TNC water systems described 
below.
    Instead of using the population served to determine the average 
flow for use in the rule's cost calculations, this alternative approach 
would re-categorize NTNC and TNC water systems based on service type 
(e.g., restaurants or parks). Service type would be obtained from SDWIS 
data. However, service type data is not always available because it is 
a voluntary SDWIS data field. Where unavailable, the service type would 
be assigned based on statistical analysis. Estimates of service type 
design flows would be obtained from engineering design manuals and best 
professional judgement if no design manual specifications exist.
    In addition, each service type category would also have 
corresponding rates for average population served and average water 
consumption. These would be used to determine contaminant exposure 
which is used in the benefit determination. For example, schools and 
churches would be two separate service type categories. They each would 
have their own corresponding average design flow, average population 
served (rather than the population as reported in SDWIS), and average 
water consumption rates. These elements could be used to estimate a 
rule's benefits and costs for the average church and the average 
school.
Mixed Systems
    Current regulations require that all systems that use any amount of 
surface water as a source be categorized as surface water systems. This 
classification applies even if the majority of water in a system is 
from a ground water source. Therefore, SDWIS does not provide the 
Agency with information to identify how many mixed systems exist. This 
information would help the Agency to better understand regulatory 
impacts.
    EPA is investigating ways to identify how many mixed systems exist 
and how many mix their ground and surface water sources at the same 
entry point or at separate entry points within the same distribution 
systems. For example, a system may have several plants/entry points 
that feed the same distribution system. One of these entry points may 
mix and treat surface water with ground water prior to its entry into 
the distribution system. Another entry point might use ground water 
exclusively for its source while a different entry point would 
exclusively use surface water. However, all three entry points would 
supply the same system classified in SDWIS as surface water.
    One method EPA could use to address this issue would be to analyze 
CWSS data then extrapolate this information to SDWIS to obtain a 
national estimate of mixed systems. CWSS data, from approximately 1,900 
systems, details sources of supply at the level of the entry point to 
the distribution system and further subdivides flow by source type. The 
Agency is considering this national estimate of mixed systems to 
regroup surface water systems for certain impact analyses when 
regulations only impact one type of source. For example, surface water 
systems that get more than fifty percent of their flow from ground 
water would be counted as a ground water system in the regulatory 
impact analysis for this rule. The Agency requests comment on this 
methodology and its applicability for use in regulatory impact 
analysis.

VII. Other Requirements

A. Regulatory Flexibility Act (RFA), as amended by the Small Business 
Regulatory Enforcement Fairness Act of 1996 (SBREFA), 5 USC 601 et seq.

1. Background
    The RFA, generally requires an agency to prepare a regulatory 
flexibility analysis of any rule subject to notice and comment 
rulemaking requirements under the Administrative Procedure Act or any 
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.
2. Use of Alternative Definition
    The RFA provides default definitions for each type of small entity. 
It 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. secs. 601(3)-(5). In 
addition to the above, to establish an alternative small business 
definition, agencies must consult with SBA's Chief Counsel for 
Advocacy.
    EPA is proposing the LT1FBR which contains provisions which apply 
to small PWSs serving fewer than 10,000 persons. This is the cut-off 
level specified by Congress in the 1996 Amendments to the Safe Drinking 
Water Act for small system flexibility provisions. Because this 
definition does not correspond to the definitions of ``small'' for 
small businesses, governments, and non-profit organizations, EPA 
requested comment on an alternative definition of ``small entity'' in 
the preamble to the proposed Consumer Confidence Report (CCR) 
regulation (63 FR 7620, February 13, 1998). Comments showed that 
stakeholders support the proposed alternative definition. EPA also 
consulted with the SBA Office of Advocacy on the definition as it 
relates to small business analysis. In the preamble to the final CCR 
regulation (63 FR 4511, August 19, 1998). EPA stated its intent to 
establish this alternative definition for regulatory flexibility 
assessments under the RFA for all drinking water regulations and has 
thus used it in this proposed rulemaking.
    In accordance with Section 603 of the RFA, EPA prepared an initial 
regulatory flexibility analysis (IRFA) that examines the impact of the 
proposed rule on small entities along with regulatory alternatives that 
could reduce that impact. The IRFA is available for review in the 
docket and is summarized below.
3. Initial Regulatory Flexibility Analysis
    As part of the 1996 amendments to the Safe Drinking Water Act 
(SDWA), Congress required the U.S. Environmental Protection Agency 
(EPA) to develop a Long Term Stage 1 Enhanced Surface Water Treatment 
Rule (LT1ESWTR) under Section 1412(b)(2)(C) which focuses on surface 
water drinking water systems that serve fewer than 10,000 persons. 
Congress also required EPA to develop a companion Filter Backwash 
Recycle Rule (FBRR) under Section 1412(b)(14) which will require that 
all surface water public water systems, regardless of size, meet new 
requirements governing the recycle of filter backwash within the 
drinking water treatment process. The goal of both the LT1ESWTR and the 
related FBRR is to provide additional protection from disease-causing 
microbial pathogens for community and non-community public water 
systems (PWSs) utilizing surface water.
    For purposes of assessing the impacts of today's rule on small 
entities, small entity is defined by systems serving fewer than 10,000 
people. The small entities directly regulated by this proposed rule are 
surface water and systems using ground water under the direct influence 
of surface water (GWUDI), using filtration and serving fewer than 
10,000 people. We have determined that the final rule would result in 
approximately 2,400 systems needing capital improvement to meet the 
turbidity requirements, approximately 3,360 systems would need to 
significantly change their

[[Page 19127]]

disinfection practices, and approximately 790 systems would need to 
make capital improvements to change the location of return of their 
filter backwash recycle stream. A discussion of the impacts on small 
entities is described in more detail in chapters six and seven of the 
Regulatory Impact Analysis of the LT1FBR (EPA, 1999).
    The following recordkeeping and reporting burdens were projected in 
the IRFA:
Turbidity Monitoring and Reporting Costs
    Utility monitoring activities at the plant level include data 
collection, data review, data reporting and monthly reporting to the 
State. The labor burden hours for data collection and review were 
calculated under the assumption that plants are using on-line 
monitoring, in the form of a SCADA or other automated data collection 
system. The data collection process requires that a plant engineer 
gather and organize turbidimeter readings from the SCADA output and 
enter them into either a spreadsheet or a log once per 8-hour shift 
(three times per day).
    After data retrieval, the turbidity data from each turbidimeter 
will be reviewed by a plant engineer once per 8-hour shift (three times 
per day) to ensure that the filters are functioning properly and are 
not displaying erratic or exceptional patterns. A monthly summary data 
report would be prepared. This task involves the review of daily 
spreadsheets and the compilation of a summary report. It is assumed to 
take one employee 8 hours per month to prepare. Recordkeeping is 
expected to take 5 hours per month. Recordkeeping entails organizing 
daily monitoring spreadsheets and monthly summary reports.
    Plant-level data will also be reviewed monthly at the system level 
to ensure that each plant in a system is in compliance with the rule. A 
system-level manager or technical worker will review the daily 
monitoring spreadsheets and monthly summary reports that are generated 
at the plant level. This task is estimated to take about 4 hours per 
month. Once the plant-level data have been reviewed, the system manager 
or technical worker will also compile a monthly system summary report. 
These reports are estimated to take 4 hours each month to prepare.
Disinfection Benchmarking Monitoring and Reporting Costs
    It is assumed that all Subpart H systems currently collect the 
daily inactivation data required to generate a disinfection profile, in 
either an electronic or paper format, and therefore would not incur 
additional data collection expenses due to microbial profiling. Costs 
per plant are divided into costs per plant using paper data, costs per 
plant using mainframe data and costs per plant using PC data. Plants 
with paper data were assumed to represent half of the number of plants 
needing benchmarking, while plants with mainframe and plants with PC 
data each represent a quarter.
Filter Backwash Monitoring and Reporting Costs
    The proposed requirements are as follows: All subpart H systems, 
regardless of size, that use conventional rapid granular filtration, 
and that return spent filter backwash, thickener supernatant, or 
liquids from dewatering process to submit a schematic diagram to the 
State showing their intended changes to move the return location above 
the point of primary coagulant addition.
    All subpart H systems, regardless of size, that use conventional 
rapid granular filtration and employ 20 or fewer filters during the 
highest production month and that use direct recycling, to perform a 
self assessment of their recycle practice and report the results to the 
State.
    All subpart H systems, regardless of system size that use direct 
filtration must submit a report of their recycling practices to the 
State. The State would then determine whether changes in recycling 
practices were warranted.
    EPA believes that the skill level required for compliance with all 
of the above recordkeeping, reporting and other compliance activities 
are similar or equivalent to the skill level required to pass the first 
level of operator certification required by most States.

Relevant Federal Rules

    EPA has issued a Stage 1 Disinfectants/Disinfection Byproducts Rule 
(DBPR) along with an Interim Enhanced Surface Water Treatment Rule 
(IESWTR) in December 1998, as required by the Safe Drinking Water Act 
Amendments of 1996. EPA proposed these rules in July 1994. The Stage 1 
DBPR includes a THM MCL of 0.080 mg/L (reduced from the existing THM 
MCL of 0.10 mg/L established in 1979) and an MCL of 0.060 mg/L for five 
haloacetic acids (another group of chlorination) as well as MCLs for 
chlorite (1.0 mg/L) and bromate (0.010 mg/L) byproducts. The Stage 1 
DBPR also finalized MRDLs for chlorine (4 mg/L as Cl2), 
chloramine (4 mg/L as Cl2) and chlorine dioxide (0.8 mg/L as 
ClO2).
    In addition, the Stage 1 DBPR includes requirements for enhanced 
coagulation to reduce the concentration of TOC in the water and thereby 
reduce DBP formation potential. The IESWTR was proposed to improve 
control of microbial pathogens and to control potential risk trade-offs 
related to the need to meet lower DBP levels under the Stage 1 DBPR.
    None of these regulations duplicate, overlap or conflict with this 
proposed rule.

Significant Alternatives

    As a result of consultations during the SBREFA process, and public 
meetings held subsequently, EPA has developed several alternative 
options to those presented in the IRFA, and has selected preferred 
alternatives for each of the turbidity, disinfection benchmarking and 
filter backwash recycle provisions. These alternatives were developed 
based on feedback from small system operators and trade associations 
and are designed to protect public health, while minimizing the burden 
to small systems. In summary, the proposed turbidity requirements are 
structured to require recordkeeping once a week as opposed to daily 
which was written in the IRFA; the proposed disinfection profile 
requirements are structured to be taken once per week, as opposed to 
daily which was written in the IRFA; and the filter backwash 
requirements have been scaled back significantly from those included in 
the IRFA, i.e. a ban on recycle is no longer being considered, nor are 
several treatment techniques now being considered that were in the IRFA 
prior to discussions with stakeholders. The provisions being proposed 
are: systems that recycle will be required to return recycle flows 
prior to the rapid mix unit; direct recycle systems will need to 
perform a self assessment to determine whether capacity is exceeded 
during recycle events, and States will determine whether recycle 
practices need to be changed based on the self-assessment; and direct 
filtration systems will need to report their recycle practices to the 
State, which will determine whether changes to recycle practices are 
required.
4. Small Entity Outreach and Small Business Advocacy Review Panel
    As required by section 609(b) of the RFA, as amended by SBREFA, EPA 
also conducted outreach to small entities and convened a Small Business 
Advocacy Review Panel to obtain advice and recommendations of 
representatives of the small entities that potentially would be subject 
to the rule's

[[Page 19128]]

requirements. The SBAR Panel produced two final reports; one for the 
LT1 provisions and the other for the filter backwash provisions. 
Although the LT1 and filter backwash provisions have since been 
combined into the same rule, the projected economic impact of the 
provisions have not significantly changed, and the relevance of SERs' 
comments has not been affected.
    The Agency invited 24 SERs to participate in the SBREFA process, 
and 16 agreed to participate. The SERs were provided with background 
information on the Safe Drinking Water Act and the LT1FBR in 
preparation for a teleconference on April 28, 1998. This information 
package included data on options as well as preliminary unit costs for 
treatment enhancements under consideration. Eight SERs provided 
comments on these materials.
    On August 25, 1998, EPA's Small Business Advocacy Chair person 
convened the Panel under section 609(b) of the Regulatory Flexibility 
Act as amended by the Small Business Regulatory Enforcement Fairness 
Act (SBREFA). In addition to its chairperson, the Panel consisted of 
the Director of the Standards and Risk Management Division of the 
Office of Ground Water and Drinking Water within EPA's Office of Water, 
the Administrator of the Office of Information and Regulatory Affairs 
within the Office of Management and Budget, and the Chief Counsel for 
Advocacy of the Small Business Administration. The SBAR Panels reports, 
Final Report of the SBREFA Small Business Advocacy Review Panel on 
EPA's Planned Proposed Rule: Long Term 1 Enhanced Surface Water 
Treatment (EPA, 1998k) and the Final Report of the SBREFA Small 
Business Advocacy Review Panel on EPA's Planned Proposed Rule: Filter 
Backwash Recycling (EPA, 1998l), contain the SERs comments on the 
components of the LT1FBR.
    The SERs were provided with additional information on potential 
costs related to LT1FBR regulatory options during teleconferences on 
September 22 and 25, 1998. Nine SERs provided additional comments 
during the September 22 teleconference, four SERs provided additional 
comments during the September 25 teleconference, and three SERs 
provided written comment on these materials.
    In general, the SERs that were consulted on the LT1FBR were 
concerned about the impact of the proposed rule on small water systems 
(because of their small staff and limited budgets), small systems' 
ability to acquire the technical and financial capability to implement 
requirements, and maintaining flexibility to tailor requirements to the 
needs and limitations of small systems. Consistent with the RFA/SBREFA 
requirements, the Panel evaluated the assembled materials and small-
entity comments on issues related to the elements of the IRFA. The 
background information provided to the SBAR Panel and the SERs are 
available for review in the water docket. A copy of the Panel report is 
also included in the docket for this proposed rule. The Panel's 
recommendations to address the SERs concerns are described next.
a. Number of Small Entities Affected
    When the IRFA was prepared, EPA initially estimated that there were 
5,165 small public water systems that use surface water or GWUDI. A 
more detailed discussion of the impact of the proposed rule and the 
number of entities affected is found in Section VI. None of the 
commenters questioned the information provided by EPA on the number and 
types of small entities which may be impacted by the LT1FBR. This 
information is based upon the national Safe Drinking Water Information 
System (SDWIS) database, which contains data on all public water 
systems in the country. The Panel believed this was a reasonable data 
source to characterize the number and types of systems impacted by the 
proposed rule.
b. Recordkeeping and Reporting
    The Panel noted that some small systems are operated by a sole, 
part time operator with many duties beyond operating and maintaining 
the drinking water treatment system and that several components of the 
proposed rule may require significant additional operator time to 
implement. These included disinfection profiling, individual filter 
monitoring, and ensuring that short-term turbidity spikes are corrected 
quickly.
    One SER stated that assumptions can be made that small systems will 
have to add an additional person to comply with the monitoring and 
recordkeeping portions of the rule. Another SER commented that the most 
viable and economical option would be to use circuit riders (a trained 
operator who travels between plants) to fill staffing needs, but the 
LT1FBR would increase the amount of time that a circuit rider would be 
required to spend at each plant. An additional option recommended by 
several SERs to reduce monitoring burden and cost was to allow the use 
of one on-line turbidimeter to measure several filters. This would 
entail less frequent monitoring of each filter but might still be 
adequate to ensure that individual filter performance is maintained.
    The proposed LT1FBR takes into consideration the recordkeeping and 
reporting concerns identified by the Panel and the SERs. For example, 
initially the Agency considered requiring systems to develop a profile 
of individual filter performance. Based on concerns from the SERs this 
requirement was eliminated. In addition, the Agency initially 
considered requiring operators to record pH, temperature, residual 
chlorine and peak hourly flow every day. This requirement has been 
scaled back to once per week to meet difficulties faced by small system 
operators. Finally, in today's proposed rule the Agency is requesting 
comment on a modification to allow one on-line turbidimeter instead of 
several to be used at the smallest size systems (systems serving fewer 
than 100 people).
c. Interaction With Other Federal Rules
    The Panel noted that the LT1FBR and Stage 1 DBP rules will affect 
small systems virtually simultaneously and that the Agency should 
analyze the net impact of these rules and consider regulatory options 
that would minimize the impact on small systems.
    One SER commented that any added responsibility or workload due to 
regulations will have to be absorbed by him and his staff. He noted 
that many systems, including his own, are losing staff through 
attrition and are unable to hire replacements. The SER stated that he 
hoped the Panel was aware of the volume of rules and regulations to 
which small systems are currently subject. As an example, the SER 
stated that he had spent a week's time collecting samples for the 
mandated tests of the Lead and Copper rule. He noted that the sampling 
had delayed important maintenance to his system by over a month.
    The Agency considered these comments when developing the 
requirements of today's proposed rule, and developed the alternatives 
with the realization that small systems will be required to implement 
several rules in a short time frame. In today's proposed rule, the 
preferred options attempt to minimize the impact on small systems by 
reducing the amount of monitoring and the amount of operator's time 
necessary to collect and analyze data. For example, under the IESWTR, 
large systems are required to monitor disinfection byproducts for 1 
year to determine whether or not they must develop a disinfection 
profile (based on

[[Page 19129]]

daily measurements of operating conditions). In response to SERs 
concerns, the Agency is proposing to eliminate the requirement for 
disinfection byproduct monitoring all together. Under the proposed 
requirements, all systems would develop a disinfection profile based on 
weekly measurements of operating parameters for 1 year. Overall, this 
will save small system operators both time and money. The proposed rule 
also requests comment on several additional strategies for reducing 
impacts.
d. Significant Alternatives
    During the SBAR panel several alternatives were discussed with the 
Panel and SERs. These alternatives and the Panel's recommendations are 
discussed next.
i. Turbidity Provisions
    During the SBAR Panel, the Agency presented the IESWTR turbidity 
provisions as appropriate components for the LT1FBR. The Panel noted 
that one SER commented that it was a fair assumption that turbidity up 
to 1 NTU maximum and 0.3 NTU in 95% of all monthly samples is a good 
indicator of two log removal of Cryptosporidium, but stressed the need 
to allow operators adequate time to respond to exceedances in automated 
systems. They were referring to the fact the small system operators are 
often away from the plant performing other duties, and cannot respond 
immediately if the turbidity levels exceed a predetermined level. The 
Panel recommended that EPA consider this limitation when developing 
reporting and recordkeeping requirements.
    The Panel also noted that another SER agreed that lowered turbidity 
level is a good indicator of overall plant performance but thought the 
0.3 NTU limit for the 95th percentile reading was too low in light of 
studies which appear to show variability and inaccuracies in low level 
turbidity measurements. This SER referenced specific data suggesting 
that current equipment used to measure turbidity levels below the 0.3 
NTU may nonetheless give readings above 0.3 which would put the system 
out of compliance. EPA has evaluated this issue in the context of the 
1997 IESWTR FACA negotiations and believes that readings below the 0.3 
NTU are reliable. Moreover, EPA notes that the SERs' concern was based 
on raw performance evaluation data that had not been fully analyzed.
    Finally, the Panel recognized that several SERs supported 
individual filter monitoring, provided there was flexibility for short 
duration turbidity spikes. Other SERs, however, noted that the 
assumption that individual filter monitoring was necessary was 
unreasonable. The Panel recommended that EPA consider the likelihood 
and significance of short duration spikes (i.e., during the first 15-30 
minutes of filter operation) when evaluating the frequency of 
individual filter monitoring and reporting requirements and the number 
and types of exceedances that will trigger requirements for 
Comprehensive Performance Evaluations (CPEs). The Panel also noted the 
concern expressed by several SERs that individual filter monitoring may 
not be practical or feasible in all situations.
    The Agency has structured today's proposed rule with an emphasis on 
providing flexibility for small systems. The individual filter 
provisions have been tailored to be easier to understand and implement 
and require less data analysis. For example, the operator can look at 
monitoring data once per week under this rule, as opposed to having to 
review turbidity data every day as the larger systems are required to 
do. The proposed rule also requests comment on several modifications to 
provide additional flexibility to small systems.
ii. Disinfection Benchmarking: Applicability Monitoring Provisions
    None of the SERs commented specifically on the applicability 
monitoring provisions which are designed to identify systems that may 
consider cutting back on their disinfection doses in order to avoid 
problems with disinfection byproducts formation. The Panel noted, 
however, that burden on small systems might be reduced if alternative 
applicability monitoring provisions were adopted. In consideration of 
the Panel's suggestions, the Agency first considered limiting the 
applicability monitoring, and has now eliminated this requirement from 
the proposal. It is optional, however, for systems who believe their 
disinfection byproduct levels are below 80% of the MCL--as required 
under the Stage 1 DBPR.
    The Panel noted SER comments that monitoring and computing Giardia 
lamblia inactivation on a daily basis for a year would place a heavy 
burden on operators that may only staff the plant for a few hours per 
day. The Panel therefore recommended that EPA consider alternative 
profiling strategies which ensure adequate public health protection, 
but will minimize monitoring and recordkeeping requirements for small 
system operators.
    The Agency considered several alternatives to the profile 
development strategies, and decided to propose that systems perform the 
necessary monitoring and record the results once per week, instead of 
every day as the larger systems are required to do. This will 
significantly reduce burden and costs for small systems.
iii. Recycling Provisions
    During the SBAR Panel, the Agency proposed several alternatives for 
consideration in the LT1FBR including a ban on recycle, a requirement 
to return recycle flow to the head of the plant, recycle flow 
equalization, and recycle flow treatment. The Panel noted the concern 
of the SERs regarding a ban on the recycle of filter backwash water. 
These concerns included the expense of filter backwash disposal and the 
economic and operational concerns of western and southwestern drinking 
water systems which depend on recycled flow to maintain adequate 
supply. The Panel strongly recommended that EPA explore alternatives to 
an outright ban on the recycle of filter backwash and other recycle 
flows.
    The Panel noted that SERs supported a requirement that all recycled 
water be reintroduced at the head of the plant. This was considered an 
element of sound engineering practice. The Panel recommended that EPA 
consider including such a requirement in the proposed rule, and 
investigate whether there are small systems for which such a 
requirement would present a significant financial and operational 
burden.
    The Panel noted that SERs agreed with the appropriateness of flow 
equalization for filter backwash. The Panel supported the concept of 
flow equalization as a means to minimize hydraulic surges that may be 
caused by recycle and the reintroduction of a large number of 
Cryptosporidium oocysts or other pathogenic contaminants to the plant 
in a brief period of time. The Panel noted that there are various ways 
of achieving flow equalization and suggested that specific requirements 
remain flexible.
    The Panel noted the concerns of SERs regarding installation of 
treatment, solely for the purpose of treating filter backwash water 
and/or recycle streams may be costly and potentially prohibitive for 
small systems. The Agency addressed this concern by allowing the States 
to determine whether recycle flow equalization or treatment is 
necessary based on the results of the self assessment prepared by the 
system rather than requiring universal flow equalization or treatment. 
This will allow site-specific

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factors to be considered and help minimize cost and burden.
e. Other Comments
    The Panel also noted the concern of several SERs that flexibility 
be provided in the compliance schedule of the rule. SERs noted the 
technical and financial limitations that some small systems will have 
to address, the significant learning curve for operators with limited 
experience, and the need to continue providing uninterrupted service as 
reasons why additional compliance time may be needed for small systems. 
The panel encouraged EPA to keep these limitations in mind in 
developing the proposed rule and provide as much compliance flexibility 
to small systems as is allowable under the SDWA. We invite comments on 
all aspects of the proposal and its impacts on small entities.
    The Agency structured the timing of the LT1ESWTR provisions 
specifically to follow the promulgation of the IESWTR. Since the IESWTR 
served as a template for the establishment of the LT1ESWTR provisions, 
the Agency decided that small systems would have an advantage by giving 
them an opportunity to see what was in the rule, and how it was 
implemented by larger systems.
    Under SDWA, systems have 3 years to comply with the requirements of 
the final rule. If capital improvements are necessary for a particular 
PWS, a State may allow the system up to an additional 2 years to comply 
with the regulation. The Agency is developing guidance manuals to 
assist the compliance efforts of small entities.

B. Paperwork Reduction Act

    The information collection requirements in this proposed rule have 
been submitted for approval to the Office of Management and Budget 
(OMB) under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. An 
Information Collection Request (ICR) document has been prepared by EPA 
(ICR No. 1928.01) and a copy may be obtained from Sandy Farmer by mail 
at OP Regulatory Information Division; U.S. Environmental Protection 
Agency (2137); 401 M St., S.W.; Washington, DC 20460, by email at 
[email protected], or by calling (202) 260-2740. A copy may 
also be downloaded off the Internet at http://www.epa.gov/icr. For 
technical information about the collection contact Jini Mohanty by 
calling (202) 260-6415.
    The information collected as a result of this rule will allow the 
States and EPA to determine appropriate requirements for specific 
systems, in some cases, and to evaluate compliance with the rule. For 
the first three years after the effective date (six years after 
promulgation) of the LT1FBR, the major information requirements are (1) 
monitor filter performance and submit any exceedances of turbidity 
requirements (i.e. exceptions reports) to the State; (2) develop a 1 
month recycle monitoring plan and submit both plan and results to the 
State; (3) submit flow monitoring plan and results to the State; and 
(4) report data on current recycle treatment (self assessment) to the 
State. The information collection requirements in Part 141, for 
systems, and Part 142, for States are mandatory. The information 
collected is not confidential.
    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.
    The preliminary estimate of aggregate annual average burden hours 
for LT1FBR is 311,486. Annual average aggregate cost estimate is 
$10,826,919 for labor, $2,713,815 for capital, and $1,898,595 for 
operation and maintenance including lab costs which is a purchase of 
service. The burden hours per response is 18.9. The frequency of 
response (average responses per respondent) is 2.7 annually. The 
estimated number of likely respondents is 6,019 (the product of burden 
hours per response, frequency, and respondents does not total the 
annual average burden hours due to rounding). Most of the regulatory 
provisions discussed in this notice entail new reporting and 
recordkeeping requirements for States, Tribes, and members of the 
regulated public. 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 are listed in 40 CFR Part 9 and 48 CFR Chapter 
15.
    Comments are requested on the Agency's need for this information, 
the accuracy of the provided burden estimates, and any suggested 
methods for minimizing respondent burden, including through the use of 
automated collection techniques. Send comments on the ICR to the 
Director, OP Regulatory Information Division; U.S. Environmental 
Protection Agency (2137); 401 M St., S.W.; Washington, DC 20460; and to 
the Office of Information and Regulatory Affairs, Office of Management 
and Budget, 725 17th St., N.W., Washington, DC 20503, marked 
``Attention: Desk Officer for EPA.'' Include the ICR number in any 
correspondence. Since OMB is required to make a decision concerning the 
ICR between 30 and 60 days after April 10, 2000, a comment to OMB is 
best assured of having its full effect if OMB receives it by May 10, 
2000. The final rule will respond to any OMB or public comments on the 
information collection requirements contained in this proposal.

C. Unfunded Mandates Reform Act

1. Summary of UMRA requirements
    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, and tribal 
governments and the private sector. Under UMRA section 202, 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 by 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 notification to 
potentially affected small governments, enabling officials of

[[Page 19131]]

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.
2. Written Statement for Rules With Federal Mandates of $100 Million or 
More
    EPA has determined that this rule does not contain a Federal 
mandate that may result in expenditures of $100 million or more for the 
State, local and Tribal governments, in the aggregate, or the private 
sector in any one year. Thus today's rule is not subject to the 
requirements of sections 202 and 205 of the UMRA. Nevertheless, since 
the estimate of annual impact is close to $100 million under certain 
assumptions EPA has prepared a written statement, which is summarized 
below, even though one is not required. A more detailed description of 
this analysis is presented in EPA's Regulatory Impact Analysis of the 
LT1FBR (EPA, 1999h) which is available for public review in the Office 
of Water docket under docket number W-99-10. The document is available 
for inspection from 9 a.m. to 4 p.m., Monday through Friday, excluding 
legal holidays. The docket is located in room EB 57, USEPA 
Headquarters, 401 M St. SW, Washington, D.C. 20460. For access to 
docket materials, please call (202) 260-3027 to schedule an 
appointment.
a. Authorizing Legislation
    Today's rule is proposed pursuant to Section 1412 (b)(2)(C) and 
1412(b)(14) of the SDWA. Section 1412 (b)(2)(C) directs EPA to 
establish a series of regulations including an interim and final 
enhanced surface water treatment rule. Section 1412(b)(14) directs EPA 
to promulgate a regulation to govern the recycling of filter backwash 
water. EPA intends to finalize the LT1FBR in the year 2000 to allow 
systems to consider the dual impact of this rule and the Stage 1 DBP 
rule on their capital investment decisions.
b. Cost Benefit Analysis
    Section VI of this preamble discusses the cost and benefits 
associated with the LT1FBR. Also, the EPA's Regulatory Impact Analysis 
of the LT1FBR (EPA, 1999h) contains a detailed cost benefit analysis. 
Today's proposal is expected to have a total annualized cost of 
approximately $ 97.5 million using a 7 percent discount rate. At a 3 
percent discount rate the annualized costs drop to $87.6 million. The 
national cost estimate includes cost for all of the rule's major 
provisions including turbidity monitoring, disinfection benchmarking 
monitoring, disinfection profiling, covered finished storage, and 
recycling. The majority of the costs for this rule will be incurred by 
the public sector. A more detailed discussion of these costs is located 
in Section VI of this preamble.
    In addition, the regulatory impact analysis includes both monetized 
benefits and descriptions of unquantified benefits for improvements to 
public health and safety the rule will achieve. Because of scientific 
uncertainty regarding LT1FBR's exposure and risk assessment, the Agency 
has used Monte Carlo methods and sensitivity analysis to assess the 
quantified benefits of today's rule. The monetary analysis was based 
upon quantification of the number of cryptosporidiosis illnesses 
avoided due to improved particulate removal that results from the 
turbidity provisions. The Agency was not able to monetize the benefits 
from the other rule provisions such as disinfection benchmarking and 
covered finished storage. The monetized annual benefits of today's rule 
range from $70.1 million to $259.4 million depending on the baseline 
and removal assumptions. Better management of recycle streams required 
by the proposal also result in nonquantifiable health risk reductions 
from disinfection resistant pathogens. The rule may also decrease 
illness caused by Giardia and other emerging disinfection resistant 
pathogens, further increasing the benefits.
    Several non-health benefits from this rule were also identified by 
EPA but were not monetized. The non-health benefits of this rule 
include outbreak response costs avoided, and possibly reduced 
uncertainty and averting behavior costs. By adding the non-monetized 
benefits with those that are monetized, the overall benefits of this 
rule increase beyond the dollar values reported.
    Various Federal programs exist to provide financial assistance to 
State, local, and Tribal governments in complying with this rule. The 
Federal government provides funding to States that have primary 
enforcement responsibility for their drinking water programs through 
the Public Water Systems Supervision Grants program. Additional funding 
is available from other programs administered either by EPA, or other 
Federal Agencies. These include EPA's Drinking Water State Revolving 
Fund (DWSRF), U.S. Department of Agriculture's Rural Utilities' Loan 
and Grant Program, and Housing and Urban Development's Community 
Development Block Grant Program.
    For example, SDWA authorizes the Administrator of the EPA to award 
capitalization grants to States, which in turn can provide low cost 
loans and other types of assistance to eligible public water systems. 
The DWSRF helps public water systems finance the cost of infrastructure 
necessary to achieve or maintain compliance with SDWA requirements. 
Each State has considerable flexibility to design its program and to 
direct funding toward the most pressing compliance and public health 
protection needs. States may also, on a matching basis, use up to ten 
percent of their DWSRF allotments each fiscal year to run the State 
drinking water program.
    Furthermore, a State can use the financial resources of the DWSRF 
to assist small systems. In fact, a minimum of 15% of a State's DWSRF 
grant must be used to provide infrastructure loans to small systems. 
Two percent of the State's grant may be used to provide technical 
assistance to small systems. For small systems that are disadvantaged, 
up to 30% of a State's DWSRF may be used for increased loan subsidies. 
Under the DWSRF, Tribes have a separate set-aside which they can use. 
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 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 up to 10,000 
people. In fiscal year 1997, the RUS had over $1.3 billion in available 
funds. Also, three sources of funding exist under the CDBG program to 
finance building and improvements of public faculties such as water 
systems. The three sources of funding include: (1) Direct grants to 
communities with populations over 200,000; (2) direct grants to States, 
which they in turn award to smaller communities, rural areas, and 
colonias in Arizona, California, New Mexico, and Texas; and (3) direct 
grants to US. Territories and Trusts. The CDBG budget for fiscal year 
1997 totaled over $4 billion dollars.
c. Estimates of Future Compliance Costs and Disproportionate Budgetary 
Effects
    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 previously and 
discussed in

[[Page 19132]]

more detail in Section VI of this preamble, accurately characterize 
future compliance costs.
    In analyzing the disproportionate impacts, EPA considered four 
measures:
    (1) The impacts of small versus large systems and the impacts 
within the five small system size categories;
    (2) The costs to public versus private water systems;
    (3) The costs to households, and;
    (4) The distribution of costs across States.
    First, small systems will experience a greater impact than large 
systems under LT1FBR because large systems are subject only to the 
recycle provisions. The Interim Enhanced Surface Water Treatment Rule 
(IESWTR) promulgated turbidity, benchmarking, and covered finished 
storage provisions for large systems in December, 1998. However, small 
systems have realized cost savings over time due to their exclusion 
from the IESWTR. Also, some provisions in the LT1FBR have been modified 
so they would not be as burdensome for small systems. Further 
information on these changes can be found in section VII.A.3.of this 
proposal.
    The second measure of impact is the relative total cost to 
privately owned water systems compared to the incurred by publicly 
owned water systems. A majority of the systems are publicly owned (60 
percent of the total). As a result, publicly owned systems will incur a 
larger share of the total costs of the rule.
    The third measure, household costs, is described in further detail 
in VI.E of this preamble. The fourth measure, distribution of costs 
across States, is described in greater detail in the RIA for today's 
proposed rule (EPA, 1999h). There is nothing to suggest that costs to 
individual systems would vary significantly from State to State, but as 
expected, the States with the greatest number of systems experience the 
greatest costs.
d. Macro-Economic Effects
    As required 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 1998, real GDP was $7,552 billion. This proposal 
would have to cost at least $18 billion to have a measurable effect. A 
regulation of less cost is unlikely to have any measurable effect 
unless it is highly focused on a particular geographic region or 
economic sector. The macro-economic effects on the national economy 
from LT1FBR should not have a measurable effect because the total 
annual cost of the preferred option is approximately $ 97.5 million per 
year (at a seven percent discount rate). The costs are not expected to 
be highly focused on a particular geographic region or sector.
e. Summary of EPA's Consultation with State, Local, and Tribal 
Governments and Their Concerns
    Consistent with the intergovernmental consultation provisions of 
section 204 of UMRA EPA has already initiated consultation with the 
governmental entities affected by this rule.
    EPA began outreach efforts to develop the LT1FBR in the summer of 
1998. Two public stakeholder meetings, which were announced in the 
Federal Register, were held on July 22-23, 1998, in Lakewood, Colorado, 
and on March 3-4, 1999, in Dallas, Texas. In addition to these 
meetings, EPA has held several formal and informal meetings with 
stakeholders including the Association of State Drinking Water 
Administrators. A summary of each meeting and attendees is available in 
the public docket for this rule. EPA also convened a Small Business 
Advocacy Review (SBAR) Panel in accordance with the Regulatory 
Flexibility Act (RFA), as amended by the Small Business Regulatory 
Enforcement Fairness Act (SBREFA) to address small entity concerns 
including those of small local governments. The SBAR Panel allows small 
regulated entities to provide input to EPA early in the regulatory 
development process. In early June, 1999, EPA mailed an informal draft 
of the LT1FBR preamble to the approximately 100 stakeholders who 
attended one of the public stakeholder meetings. Members of trade 
associations and the SBREFA Panel also received the draft preamble. EPA 
received valuable comments and stakeholder input from 15 State 
representatives, trade associations, environmental interest groups, and 
individual stakeholders. The majority of concerns dealt with reducing 
burden on small systems and maintaining flexibility. After receipt of 
comments, EPA made every effort to make modifications to address these 
concerns.
    To inform and involve Tribal governments in the rulemaking process, 
EPA presented the LT1FBR at three venues: the 16th Annual Consumer 
Conference of the National Indian Health Board, the annual conference 
of the National Tribal Environmental Council, and the OGWDW/Inter 
Tribal Council of Arizona, Inc. tribal consultation meeting. Over 900 
attendees representing tribes from across the country attended the 
National Indian Health Board's Consumer Conference and over 100 tribes 
were represented at the annual conference of the National Tribal 
Environmental Council. At both conferences, an OGWDW representative 
conducted two workshops on EPA's drinking water program and upcoming 
regulations, including the LT1FBR.
    At the OGWDW/Inter Tribal Council of Arizona meeting, 
representatives from 15 tribes participated. The presentation materials 
and meeting summary were sent to over 500 tribes and tribal 
organizations. Additionally, EPA contacted each of our 12 Native 
American Drinking Water State Revolving Fund Advisors to invite them, 
and representatives of their organizations to the stakeholder meetings 
described previously. A list of tribal representatives contacted can be 
found in the docket for this rule.
    The primary concern expressed by State, local and Tribal 
governments is the difficulty the smallest systems will encounter in 
adequately staffing drinking water treatment facilities to perform the 
monitoring and reporting associated with the new requirements. Today's 
proposal attempts to minimize the monitoring and reporting burden to 
the greatest extent feasible and still accomplish the rule's objective 
of protecting public health. The Agency believes the monitoring and 
reporting requirements are necessary to ensure consumers served by 
small systems receive the same level of public health protection as 
consumers served by large systems. Summaries of the meetings have been 
included in the public docket for this rulemaking.
f. Regulatory Alternatives Considered
    As required under Section 205 of the UMRA, EPA considered several 
regulatory alternatives for individual filter monitoring and 
disinfection benchmarking, as well as several alternative strategies 
for addressing recycle practices. A detailed discussion of these 
alternatives can be found in Section IV and also in the RIA for today's 
proposed rule (EPA, 1999h). Today's proposal also seeks comment on 
several regulatory alternatives that EPA will consider for the final 
rule.

[[Page 19133]]

g. Selection of the Least Costly, Most-Cost Effective or Least 
Burdensome Alternative That Achieves the Objectives of the Rule
    As discussed previously, EPA has considered and requested comment 
on various regulatory options that would reduce Cryptosporidium 
occurrence in the finished water of surface water systems. The Agency 
believes that the preferred option for turbidity performance, 
disinfection benchmarking, and recycle management are the most cost 
effective combination of options to achieve the rule's objective; the 
reduction of illness and death from Cryptosporidium occurrence in the 
finished water of PWSs using surface water. The Agency will carefully 
review comments on the proposal and assess suggested changes to the 
requirements.
3. Impacts on Small Governments
    In developing this proposal, EPA consulted with small governments 
to address impacts of regulatory requirements in the rule that might 
significantly or uniquely affect small governments. As discussed 
previously, a variety of stakeholders, including small governments, 
were provided the opportunity for timely and meaningful participation 
in the regulatory development process through the SBREFA panel, public 
stakeholder and Tribal meetings. EPA used these processes to notify 
potentially affected small governments of regulatory requirements being 
considered and provided officials of affected small governments with an 
opportunity to have meaningful and timely input to the regulatory 
development process.
    In addition, EPA will educate, inform, and advise small systems, 
including those run by small governments, about LT1FBR requirements. 
One of the most important components of this outreach effort will be 
the Small Entity Compliance Guide, required by the Small Business 
Regulatory Enforcement Fairness Act of 1996. This plain-English guide 
will explain what actions a small entity must take to comply with the 
rule. Also, the Agency is developing fact sheets that concisely 
describe various aspects and requirements of the LT1FBR and detailed 
guidance manuals to assist the compliance effort of PWSs and small 
government entities.

D. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (NTAA), Public Law No. 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, business practices) that are developed or adopted 
by voluntary consensus standards bodies. The NTAA directs EPA to 
provide Congress, through the Office of Management and Budget, 
explanations when the Agency decides not to use available and 
applicable voluntary consensus standards.
    Today's rule requires the use of previously approved technical 
standards for the measurement of turbidity. In previous rulemakings, 
EPA approved three methods for measuring turbidity in drinking water. 
These can be found in 40 CFR, Part 141.74 (a). Turbidity is a method-
defined parameter and therefore modifications to any of the three 
approved methods requires prior EPA approval. One of the approved 
methods was published by the Standard Methods Committee of American 
Public Health Association, the American Water Works Association, and 
the Water Environment Federation, the latter being a voluntary 
consensus standard body. That method, Method 2130B (APHA, 1995), is 
published in Standard Methods for the Examination of Water and 
Wastewater (19th ed.). Standard Methods is a widely used reference 
which has been peer-reviewed by the scientific community. In addition 
to this voluntary consensus standard, EPA approved two additional 
methods for the measurement of turbidity. One is the Great Lakes 
Instrument Method 2, which can be used as an alternate test procedure 
for the measurement of turbidity (Great Lakes Instruments, 1992). 
Second, the Agency approved revised EPA Method 180.1 for turbidity 
measurement in August 1993 in Methods for the Determination of 
Inorganic Substances in Environmental Samples (EPA-600/R-93-100) (EPA, 
1993).
    In 1994, EPA reviewed and rejected an additional technical 
standard, a voluntary consensus standard, for the measurement of 
turbidity, the ISO 7027 standard, an analytical method which measures 
turbidity at a higher wavelength than the approved test measurement 
standards. ISO 7027 measures turbidity using either 90 deg. scattered 
or transmitted light depending on the turbidity concentration 
evaluated. Although instruments conforming to ISO 7027 specifications 
are similar to the GLI instrument, only the GLI instrument uses pulsed, 
multiple detectors to simultaneously read both 90 deg. scattered and 
transmitted light. EPA has no data upon which to evaluate whether the 
separate 90 deg. scattered or transmitted light measurement 
evaluations, according to the ISO 7027 method, would produce results 
that are equivalent to results produced using GLI Method 2, Standard 
Method 2130B (APHA, 1995), or EPA Method 180.1 (EPA, 1993).
    Today's proposed rule also requires continuous individual filter 
monitoring for turbidity and requires PWSs to calibrate the individual 
turbidimeter according to the turbidimeter manufacturer's instructions. 
These calibration instructions may constitute technical standards as 
that term is defined in the NTTAA. EPA has looked for voluntary 
consensus standards with regard to calibration of turbidimeters. The 
American Society for Testing and Materials (ASTM) is developing such 
voluntary consensus standards, however, there do not appear to be any 
voluntary consensus standards available at this time. EPA welcomes 
comments on this aspect of the proposed rulemaking and, specifically 
invites the public to identify potentially applicable voluntary 
consensus standards and to explain why such standards should be used in 
this regulation.
    EPA plans to implement in the future a performance-based 
measurement system (PBMS) that would allow the option of using either 
performance criteria or reference methods in its drinking water 
regulatory programs. The Agency is currently determining the specific 
steps necessary to implement PBMS in its programs and preparing an 
implementation plan. Final decisions have not yet been made concerning 
the implementation of PBMS in water programs. However, EPA is currently 
evaluating what relevant performance characteristics should be 
specified for monitoring methods used in the water programs under a 
PBMS approach to ensure adequate data quality. EPA would then specify 
performance requirements in its regulations to ensure that any method 
used for determination of a regulated analyte is at least equivalent to 
the performance achieved by other currently approved methods.
    Once EPA has made its final determinations regarding implementation 
of PBMS in programs under the Safe Drinking Water Act, EPA would 
incorporate specific provisions of PBMS into its regulations, which may 
include specification of the performance characteristics for 
measurement of regulated contaminants in the drinking water program 
regulations.

[[Page 19134]]

E. 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:
    1. 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, 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 entitlement, 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.'' As 
such, this action was submitted to OMB for review. Changes made in 
response to OMB suggestions or recommendations will be documented in 
the public record.

F. Executive Order 12898: Environmental Justice

    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. The 
Agency has considered environmental justice related issues concerning 
the potential impacts of this action and consulted with minority and 
low-income stakeholders.
    This preamble has discussed many times how the IESWTR served as a 
template for the development of the LT1FBR. As such, the Agency also 
built on the efforts conducted during the IESWTRs development to comply 
with E.O. 12898. On March 12, 1998, the Agency held a stakeholder 
meeting to address various components of pending drinking water 
regulations and how they may impact sensitive sub-populations, minority 
populations, and low-income populations. Topics discussed included 
treatment techniques, costs and benefits, data quality, health effects, 
and the regulatory process. Participants included national, State, 
tribal, municipal, and individual stakeholders. EPA conducted the 
meetings by video conference call between eleven cities. This meeting 
was a continuation of stakeholder meetings that started in 1995 to 
obtain input on the Agency's Drinking Water Programs. The major 
objectives for the March 12, 1998 meeting were:
    (1) Solicit ideas from stakeholders on known issues concerning 
current drinking water regulatory efforts;
    (2) Identify key issues of concern to stakeholders, and;
    (3) Receive suggestions from stakeholders concerning ways to 
increase representation of communities in OGWDW regulatory efforts.
    In addition, EPA developed a plain-English guide specifically for 
this meeting to assist stakeholders in understanding the multiple and 
sometimes complex issues surrounding drinking water regulation.
    The LT1FBR applies to community water systems, non-transient non-
community water systems, and transient non-community water systems that 
use surface water or ground water under the direct influence (GWUDI) as 
their source water for PWSs serving less than 10,000 people. The 
recycle provisions apply to all conventional and direct surface water 
or GWUDI systems regardless of size.
    EPA believes this rule will provide equal health protection for all 
minority and low-income populations served by systems regulated under 
this rule from exposure to microbial contamination. These requirements 
will also be consistent with the protection already afforded to people 
being served by systems with larger population bases.

G. Executive Order 13045: Protection of Children from Environmental 
Health Risks 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 E.O. 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.
    While this proposed rule is not subject to the Executive Order 
because it is not economically significant as defined by E.O. 12866, we 
nonetheless have reason to believe that the environmental health or 
safety risk addressed by this action may have a disproportionate effect 
on children. Accordingly, EPA evaluated available data on the health 
effect of Cryptosporidium on children. The results of this evaluation 
are contained in Section II.B of this preamble and in the LT1FBR RIA 
(EPA, 1999h). A copy of the RIA and supporting documents is available 
for public review in the Office of Water docket at 401 M St. SW, 
Washington, D.C.
    The risk of illness and death due to cryptosporidiosis depends on 
several factors, including the age, nutrition, exposure, and the immune 
status of the individual. Information on mortality from diarrhea shows 
the greatest risk of mortality occurring among the very young and 
elderly (Gerba et al., 1996). Specifically, young children are a 
vulnerable population subject to infectious diarrhea caused by 
Cryptosporidium (CDC 1994). Cryptosporidiosis is prevalent worldwide, 
and its occurrence is higher in children than in adults (Fayer and 
Ungar, 1986).
    Cryptosporidiosis appears to be more prevalent in populations that 
may not have established immunity against the disease and may be in 
greater contact with environmentally contaminated surfaces, such as 
infants (DuPont, et al., 1995). Once a child is infected it may spread 
the disease to other children or family members. Evidence of such 
secondary transmission of cryptosporidiosis from children to household 
and other close contacts has been found in many outbreak investigations 
(Casemore, 1990; Cordell et al., 1997; Frost et al., 1997). Chapell et 
al., 1999, found that prior exposure to Cryptosporidium through the 
ingestion of a low oocyst dose provides protection from infection and 
illness. However, it is not known whether this immunity is life-long or 
temporary. Data also indicate that either mothers confer short term 
immunity to their children or that babies have reduced exposure to 
Cryptosporidium, resulting in a decreased incidence of infection during 
the first year of life. For example, in a survey of over 30,000 stool 
sample analyses from different UK patients, the 1-5 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

[[Page 19135]]

six months of age showed a higher rate of infection than individuals 
aged fewer than six months (Casemore, 1990).
    EPA has not been able to quantify the differential health effects 
for children as a result of Cryptosporidium-contaminated drinking 
water. However, the result of the LT1FBR will be a reduction in the 
risk of illness for the entire population, including children. 
Furthermore, the available anecdotal evidence indicates that children 
may be more vulnerable to cryptosporidiosis than the rest of the 
population. The LT1FBR would, therefore, result in greater risk 
reduction for children than for the general population.
    The public is invited to submit or identify peer-reviewed studies 
and data, of which EPA may not be aware, that assessed results of early 
life exposure to Cryptosporidium.

H. 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 
will consult with the National Drinking Water Advisory Council (NDWAC) 
and the Secretary of Health and Human Services and request comment from 
the Science Advisory Board on the proposed LT1FBR.

I. Executive Order 13132: Executive Orders on 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 section 6 of 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 proposed regulation. EPA also may not issue a regulation 
that has federalism implications and that preempts State law, unless 
the Agency consults with State and local officials early in the process 
of developing the proposed regulation.
    If EPA complies by consulting, Executive Order 13132 requires EPA 
to provide to the Office of Management and Budget (OMB), in a 
separately identified section of the preamble to the final rule, a 
federalism summary impact statement (FSIS). The FSIS must include a 
description of the extent of EPA's prior consultation with State and 
local officials, a summary of the nature of their concerns and the 
agency's position supporting the need to issue the regulation, and a 
statement of the extent to which the concerns of State and local 
officials have been met. Also, when EPA transmits a draft final rule 
with federalism implications to OMB for review pursuant to Executive 
Order 12866, EPA must include a certification from the agency's 
Federalism Official stating that EPA has met the requirements of 
Executive Order 13132 in a meaningful and timely manner.
    EPA has concluded that this proposed rule may have federalism 
implications since it may impose substantial direct compliance costs on 
local governments, and the Federal government will not provide the 
funds necessary to pay those cost. Accordingly, EPA provides the 
following FSIS as required by section 6(b) of Executive Order 13132.
    As discussed further in section VII.C.2.e, EPA met with a variety 
of State and local representatives, who provided meaningful and timely 
input in the development of the proposed rule. Summaries of the 
meetings have been included in the public record for this proposed 
rulemaking. EPA consulted extensively with State, local, and tribal 
governments. For example, two public stakeholder meetings were held on 
July 22-23, 1998, in Lakewood, Colorado, and on March 3-4, 1999, in 
Dallas, Texas. Several key issues were raised by stakeholders regarding 
the LT1 provisions, many of which were related to reducing burden and 
maintaining flexibility. The Office of Water was able to significantly 
reduce burden and increase flexibility by tailoring requirements to 
reduce monitoring, reporting, and recordkeeping requirements faced by 
small systems. These modifications and others aided in lowering the 
cost of the LT1FBR by $87 million (from $184.5 million to $97.5 
million). It should be noted that this rule is important because it 
will reduce the level of Cryptosporidium in filtered finished drinking 
water supplies through improvements in filtration and recycle practices 
resulting in a reduced likelihood of outbreaks of cryptosporidiosis. 
The rule is also expected to increase the level of protection from 
exposure to other pathogens (i.e., Giardia and other waterborne 
bacterial or viral pathogens). Because consultation on this proposed 
rule occurred before the November 2, 1999 effective date of Executive 
Order 13132, EPA will initiate discussions with State and local elected 
officials regarding the implications of this rule during the public 
comment period.

J. Executive Order 13084: Consultation and Coordination With Indian 
Tribal Governments

    Under Executive Order 13084, EPA may not issue a regulation that is 
not required by statute, that significantly or uniquely affects the 
communities of Indian tribal governments, and that imposes substantial 
direct compliance costs on those communities, unless the Federal 
government provides the funds necessary to pay the direct compliance 
costs incurred by the tribal governments or EPA consults with those 
governments. If EPA complies by consulting, Executive Order 13084 
requires EPA to provide to the Office of Management and Budget, in a 
separately identified section of the preamble to the rule, a 
description of the extent of EPA's prior consultation with 
representatives of affected tribal governments, a summary of the nature 
of their concerns, and a statement supporting the need to issue the 
regulation. In addition, Executive Order 13084 requires EPA to develop 
an effective process permitting elected officials and other 
representatives of Indian tribal governments ``to provide meaningful 
and timely input in the development of regulatory policies on matters 
that significantly or uniquely affect their communities.''
    EPA has concluded that this rule may significantly or unique affect 
the communities of Indian tribal governments. It may also impose 
substantial direct compliance costs on such communities. The Federal 
government will not provide the funds necessary to pay all the direct 
costs incurred by the Tribal governments in complying with the rule. In 
developing this rule, EPA consulted with representatives of Tribal 
governments pursuant to UMRA and Executive Order 13084. EPA held 
extensive meetings that provided Indian Tribal governments the 
opportunity for meaningful and timely input in the development of the 
proposed rule. Summaries of the meetings have been included in the 
public docket for this rulemaking. EPA's consultation, the nature of 
the government's concerns, and the position supporting the need for

[[Page 19136]]

this rule are discussed in Section VII.C.2.e, which addresses 
compliance with UMRA.

K. Likely Effect of Compliance with the LT1FBR on the Technical, 
Financial, and Managerial Capacity of Public Water Systems

    Section 1420(d)(3) of the SDWA as amended requires that, in 
promulgating a NPDWR, the Administrator shall include an analysis of 
the likely effect of compliance with the regulation on the technical, 
financial, and managerial capacity of public water systems. This 
analysis can be found in the LT1FBR RIA (EPA, 1999h).
    Overall water system capacity is defined in EPA guidance (EPA, 
1998j) as the ability to plan for, achieve, and maintain compliance 
with applicable drinking water standards. Capacity has three 
components: technical, managerial, and financial.
    Technical capacity is the physical and operational ability of a 
water system to meet SDWA requirements. Technical capacity 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. A water system's 
technical capacity can be determined by examining key issues and 
questions, including:
     Source water adequacy. Does the system have a reliable 
source of drinking water? Is the source of generally good quality and 
adequately protected?
     Infrastructure adequacy. Can the system provide water that 
meets SDWA standards? What is the condition of its infrastructure, 
including well(s) or source water intakes, treatment, storage, and 
distribution? What is the infrastructure's life expectancy? Does the 
system have a capital improvement plan?
     Technical knowledge and implementation. Is the system's 
operator certified? Does the operator have sufficient technical 
knowledge of applicable standards? Can the operator effectively 
implement this technical knowledge? Does the operator understand the 
system's technical and operational characteristics? Does the system 
have an effective operation and maintenance program?
    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. Managerial capacity can be assessed 
through key issues and questions, including:
     Ownership accountability. Are the system owner(s) clearly 
identified? Can they be held accountable for the system?
     Staffing and organization. Are the system operator(s) and 
manager(s) clearly identified? Is the system properly organized and 
staffed? Do personnel understand the management aspects of regulatory 
requirements and system operations? Do they have adequate expertise to 
manage water system operations? Do personnel have the necessary 
licenses and certifications?
     Effective external linkages. Does the system interact well 
with customers, regulators, and other entities? Is the system aware of 
available external resources, such as technical and financial 
assistance?
    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. Financial capacity can 
be assessed through key issues and questions, including:
     Revenue sufficiency. Do revenues cover costs? Are water 
rates and charges adequate to cover the cost of water?
     Credit worthiness. Is the system financially healthy? Does 
it have access to capital through public or private sources?
     Fiscal management and controls. Are adequate books and 
records maintained? Are appropriate budgeting, accounting, and 
financial planning methods used? Does the system manage its revenues 
effectively?
    Systems not making significant modifications to the treatment 
process to meet LT1FBR requirements are not expected to require 
significantly increased technical, financial, or managerial capacity.

L. Plain Language

    Executive Order 12866 and the President's memorandum of June 1, 
1998, require each agency to write its rules in plain language. We 
invite your comments on how to make this proposed rule easier to 
understand. For example: Have we organized the material to suit your 
needs? Are the requirements in the rule clearly stated? Does the rule 
contain technical language or jargon that is not clear? Would a 
different format (grouping and order of sections, use of headings, 
paragraphing) make the rule easier to understand? Would shorter 
sections make the final rule easier to understand? Could we improve 
clarity by adding tables, lists, or diagrams? What else could we do to 
make the rule easier to understand?

VIII. Public Comment Procedures

    EPA invites you to provide your views on this proposal, approaches 
we have not considered, the potential impacts of the various options 
(including possible unintended consequences), and any data or 
information that you would like the Agency to consider. Many of the 
sections within today's proposed rule contain ``Request for Comment'' 
portions which the Agency is also interested in receiving comment on.

A. Deadlines for Comment

    Send your comments on or before June 9, 2000. Comments received 
after this date may not be considered in decision making on the 
proposed rule. Again, comments must be received or post-marked by 
midnight June 9, 2000.

B. Where To Send Comment

    Send an original and 3 copies of your comments and enclosures 
(including references) to W-99-10 Comment Clerk, Water Docket (MC4101), 
USEPA, 401 M, Washington, D.C. 20460. Comments may also be submitted 
electronically to [email protected]. Electronic comments must 
be submitted as an ASCII, WP5.1, WP6.1 or WP8 file avoiding the use of 
special characters and form of encryption. Electronic comments must be 
identified by the docket number W-99-10. Comments and data will also be 
accepted on disks in WP 5.1, 6.1, 8 or ASCII file format. Electronic 
comments on this notice may be filed online at many Federal Depository 
Libraries. Those who comment and want EPA to acknowledge receipt of 
their comments must enclose a self-addressed stamped envelope. No 
facsimiles (faxes) will be accepted. Comments may also be submitted 
electronically to [email protected].

C. Guidelines for Commenting

    To ensure that EPA can read, understand and therefore properly 
respond to comments, the Agency would prefer that commenters cite, 
where possible, the paragraph(s) or sections in the notice or 
supporting documents to which each comment refers. Commenters should 
use a separate paragraph for each issue discussed. Note that the Agency 
is not soliciting comment on, nor will it respond to, comments on 
previously published regulatory language that is included in this 
notice to ease the reader's understanding of proposed language. You may 
find the following

[[Page 19137]]

suggestions helpful for preparing your comments:
    1. Explain your views as clearly as possible.
    2. Describe any assumptions that you used.
    3. Provide solid technical information and/or data to support your 
views.
    4. If you estimate potential burden or costs, explain how you 
arrived at the estimate.
    5. Indicate what you support, as well as what you disagree with.
    6. Provide specific examples to illustrate your concerns.
    7. Make sure to submit your comments by the deadline in this 
proposed rule.
    8. At the beginning of your comments (e.g., as part of the 
``Subject'' heading), be sure to properly identify the document you are 
commenting on. You can do this by providing the docket control number 
assigned to the proposed rule, along with the name, date, and Federal 
Register citation.

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List of Subjects

40 CFR Part 141

    Environmental protection, Chemicals, Indians-lands, 
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: March 27, 2000.
Carol M. Browner,
Administrator.
    For the reasons set forth in the preamble, title 40 chapter I of 
the Code of Federal Regulations is proposed to be amended as follows:

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-1, 300g-2, 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4, 300j-9, and 300j-11.

    4. Section 141.2 is amended by revising the definition of ``Ground 
water under the direct influence of surface water'' and ``Disinfection 
profile'' and adding the following definitions in alphabetical order to 
read as follows:


Sec. 141.2  Definitions.

* * * * *
    Direct recycle is the return of recycle flow within the treatment 
process of a public water system without first passing the recycle flow 
through a treatment process designed to remove solids, a raw water 
storage reservoir, or some other structure with a volume equal to or 
greater than the volume of spent filter backwash water produced by one 
filter backwash event.
* * * * *
    Disinfection profile is a summary of Giardia lamblia inactivation 
through the treatment plant, from the point of disinfectant application 
to the first customer. The procedure for developing a disinfection 
profile is contained in Sec. 141.172 (Disinfection profiling and 
benchmarking) in subpart P and Secs. 141.530-141.536 (Disinfection 
profile) in subpart T of this part.
* * * * *
    Equalization is the detention of recycle flow in a structure with a 
volume equal to or greater than the volume of spent filter backwash 
produced by one filter backwash event.
* * * * *
    Ground water under the direct influence of surface water (GWUDI) 
means any water beneath the surface of the ground with significant 
occurrence of insects or other macroorganisms, algae, or large-diameter 
pathogens such as Giardia lamblia or Cryptosporidium, or significant 
and relatively rapid shifts in water characteristics such as turbidity, 
temperature, conductivity, or pH which closely correlate to 
climatological or surface water conditions. Direct influence must be 
determined for individual sources in accordance with criteria 
established by the State. The State determination of direct influence 
may be based on site-specific measurements of water quality and/or 
documentation of well construction characteristics and geology with 
field evaluation.
* * * * *
    Membrane Filtration means any filtration process using tubular or 
spiral wound elements that exhibits the ability to mechanically 
separate water from other ions and solids by creating a pressure 
differential and flow across a membrane with an absolute pore size 1 
micron.
* * * * *
    Operating capacity is the maximum finished water production rate 
approved by the State drinking water program.
* * * * *
    Recycle is the return of any water, solid, or semisolid generated 
by plant treatment processes, operational processes, maintenance 
processes, and residuals treatment processes into a PWS's primary 
treatment processes.
* * * * *
    5. Section 141.32 is amended by revising paragraph (e)(10) to read 
as follows:


Sec. 141.32  Public notification.

* * * * *
    (e) * * *
    (10) Microbiological contaminants (for use when there is a 
violation of the treatment technique requirements for filtration and 
disinfection in subpart H, subpart P, or subpart T of this part). The 
United States Environmental Protection Agency (EPA) sets drinking water 
standards and has determined that the presence of microbiological 
contaminants are a health concern at certain levels of exposure. If 
water is inadequately treated, microbiological contaminants in that 
water may cause disease. Disease symptoms may include diarrhea, cramps, 
nausea, and possibly jaundice, and any associated headaches and 
fatigue. These symptoms, however, are not just associated with disease-
causing organisms in drinking water, but also may be caused by a number 
of factors other than your drinking water. EPA has set enforceable 
requirements for treating drinking water to reduce the risk of these 
adverse health effects. Treatment such as filtering and disinfecting 
the water removes or destroys microbiological contaminants. Drinking 
water which is treated to meet EPA requirements is associated with 
little to none of this risk and should be considered safe.
* * * * *
    6. Section 141.70 is amended by revising paragraph (b)(2) and 
adding paragraph (e) to read as follows:


Sec. 141.70  General requirements.

* * * * *
    (b) * * *
    (2) It meets the filtration requirements in Sec. 141.73, the 
disinfection

[[Page 19142]]

requirements in Sec. 141.72(b) and the recycle requirements in 
Sec. 141.76.
* * * * *
    (e) Additional requirements for systems serving fewer than 10,000 
people. In addition to complying with requirements in this subpart, 
systems serving fewer than 10,000 people must also comply with the 
requirements in subpart T of this part.
    7. Section 141.73 is amended by adding paragraph (a)(4) and 
revising paragraph (d) to read as follows:


Sec. 141.73  Filtration.

* * * * *
    (a) * * *
    (4) Beginning [DATE 36 MONTHS AFTER DATE OF PUBLICATION OF FINAL 
RULE IN THE FEDERAL REGISTER], systems serving fewer than 10,000 people 
must meet the turbidity requirements in Secs. 141.550 through 141.553.
* * * * *
    (d) Other filtration technologies. A public water system may use a 
filtration technology not listed in paragraphs (a) through (c) of this 
section if it demonstrates to the State, using pilot plant studies or 
other means, that the alternative filtration technology, in combination 
with disinfection treatment that meets the requirements of 
Sec. 141.72(b), consistently achieves 99.9 percent removal and/or 
inactivation of Giardia lamblia cysts and 99.99 percent removal and/or 
inactivation of viruses. For a system that makes this demonstration, 
the requirements of paragraph (b) of this section apply. Beginning 
December 17, 2001, systems serving at least 10,000 people must meet the 
requirements for other filtration technologies in paragraph (b) of this 
section. Beginning [DATE 36 MONTHS AFTER DATE OF PUBLICATION OF FINAL 
RULE IN THE FEDERAL REGISTER], systems serving fewer than 10,000 people 
must meet the requirements for treatment technologies in Secs. 141.550 
through141.553.
    8. Subpart H is amended by adding a new Sec. 141.76 to subpart H to 
read as follows:


Sec. 141.76  Recycle Provisions.

    (a) Public water systems employing conventional filtration or 
direct filtration that use surface water or ground water under the 
direct influence of surface water and recycle within the treatment 
process must meet all applicable requirements of this section. 
Requirements are summarized in the following table.

                Recycle Provisions for subpart H Systems
------------------------------------------------------------------------
                                            You are required to meet the
            If you are a . . .                  requirements in . . .
------------------------------------------------------------------------
(1) subpart H public water system           Sec.  141.76 (b).
 employing conventional or direct
 filtration returning spent filter
 backwash, thickener supernatant, or
 liquids from dewatering processes
 concurrent with or downstream of the
 point of primary coagulant addition.
(2) Plant that is part of a subpart H       Sec.  141.76 (c).
 public water system, employ conventional
 filtration treatment, practice direct
 recycle, employ 20 or fewer filters to
 meet production requirements during the
 highest production month in the 12 month
 period [date 60 months after publication
 of final rule], and recycle spent filter
 backwash or thickener supernatant to the
 treatment process.
(3) subpart H public water system           Sec.  141.76 (d).
 practicing direct filtration and
 recycling to the treatment process.
------------------------------------------------------------------------

    (b) Recycle return location. All subpart H systems employing 
conventional filtration or direct filtration and returning spent filter 
backwash, thickener supernatant, or liquids from dewatering processes 
at or after the point of primary coagulant addition must return these 
recycle flows prior to the point of primary coagulant addition by [DATE 
60 MONTHS AFTER DATE OF PUBLICATION OF FINAL RULE IN THE FEDERAL 
REGISTER]. The system must apply to the State for approval of the 
change in recycle location before the system implements it.
    (1) All subpart H systems employing conventional filtration or 
direct filtration, returning spent filter backwash, thickener 
supernatant, or liquids from dewatering processes at or after the point 
of primary coagulant addition must submit a plant schematic to the 
State by [DATE 42 MONTHS AFTER DATE OF PUBLICATION OF FINAL RULE IN THE 
FEDERAL REGISTER] showing the current recycle return location(s) for 
the recycle stream(s) and the new return location that will be used to 
establish compliance. The system must keep the plant schematic on file 
for review during sanitary surveys.
    (2) Softening systems may recycle process solids at the point of 
lime addition preceding the softening process to improve treatment 
efficiency. Process solids may not be returned prior to the point of 
lime addition. Softening systems shall not return spent filter 
backwash, thickener supernatant, or liquids from dewatering processes 
to a location other than prior to the point of primary coagulant 
addition unless an alternate location is granted by the State.
    (3) Contact clarification systems may recycle process solids 
directly into the contactor. Contact clarification systems shall not 
return spent filter backwash, thickener supernatant, or liquids from 
dewatering processes to a location other than prior to the point of 
primary coagulant addition unless an alternate location is granted by 
the State.
    (4) Systems may apply to the State to return spent filter backwash, 
thickener supernatant, or liquids from dewatering processes to an 
alternate location other than prior to the point of primary coagulant 
addition.
    (c) Plants that are part of subpart H public water systems that 
employ conventional rapid granular filtration, practice direct recycle, 
employ 20 or fewer filters to meet production requirements during the 
highest production month in the 12 month period prior to [DATE 60 
MONTHS AFTER PUBLICATION OF FINAL RULE IN THE Federal Register], and 
recycle spent filter backwash or thickener supernatant to the primary 
treatment process shall complete a recycle self assessment, as 
stipulated in paragraphs(c)(1) and (c)(2) by [Date 51 Months After Date 
of Publication of Final Rule in the Federal Register]. Systems required 
to perform the self assessment shall:
    (1) Submit a recycle self assessment monitoring plan to the State 
no later than [Date 39 Months After Date of Publication of Final Rule 
in the Federal Register]. At a minimum, the monitoring plan must 
identify the highest water production month during

[[Page 19143]]

which monitoring will be conducted, contain a schematic identifying the 
location of raw and recycle flow monitoring devices, describe the type 
of flow monitoring devices to be used, identify the system's State 
approved operating capacity, and describe how data from the raw and 
recycle flow monitoring devices will be simultaneously retrieved and 
recorded.
    (2) Implement the following recycle self assessment monitoring and 
analysis steps:
    (i) Steps for Implementation of Recycle Self Assessment:
    (A) Identify the highest water production month during the 12 month 
period preceding [Date 36 Months After Date of Publication of Final 
Rule in the Federal Register].
    (B) Perform the monitoring described in paragraph (c)(2)(i)(C) of 
this section during the 12 month period after submission of the 
monitoring plan to the State. The twelve month period must begin no 
later than [Date 39 Months After Date of Publication of Final Rule in 
the Federal Register].
    (C) For each day of the month identified in paragraph (c)(2)(i)(A) 
of this section, separately monitor source water influent flow and 
recycle flow before their confluence during one filter backwash recycle 
event per day, at three minute intervals during the duration of the 
event. Monitoring must be performed between 7:00 a.m. and 8:00 p.m. 
Systems that do not have a filter backwash recycle event every day 
between 7:00 am and 8:00 p.m. must monitor one filter backwash recycle 
event per day, any three days of the week, for each week during the 
month of monitoring, between 7:00 a.m. and 8:00 p.m. Record the time 
filter backwash was initiated, the influent and recycle flow at three 
minute intervals during the duration of the event, and the time the 
filter backwash recycle event ended. Record the number of filters in 
use when the filter backwash recycle event is monitored.
    (D) Calculate the arithmetic average of all influent and recycle 
flow values taken at three minute intervals in paragraph (c)(2)(i)(c) 
of this section. Sum the arithmetic average calculated for raw water 
influent and recycle flows. Record this value and the date the 
monitoring was performed. This value is referred to as event flow.
    (E) After the month of monitoring is complete, order the event 
flows in a list of increasing order, from lowest to highest. Highlight 
the event flows that exceed State approved operating capacity and then 
sum the number of event flows highlighted.
    (ii) [Reserved]
    (3) Subpart H systems performing recycle self assessments are 
required to report the results of the self assessment and supporting 
documentation to the State within one month of completing raw water 
influent and recycle flow monitoring. The report must be submitted no 
later than [DATE 52 MONTHS AFTER DATE OF PUBLICATION OF FINAL RULE IN 
THE FEDERAL REGISTER]. If the State determines the self assessment is 
incomplete or inaccurate, it may require the system to correct 
deficiencies or perform an additional self assessment. At a minimum, 
the report must contain the following information:
    (i) Minimum Information Included in Recycle Assessment Report to 
State:
    (A) All source and recycle flow measurements taken and the dates 
they were taken. For all events monitored, report the times the filter 
backwash recycle event was initiated, the flow measurements taken at 
three minute intervals, and the time the filter backwash recycle event 
ended. Report the number of filters in use when the backwash recycle 
event is monitored.
    (B) All data used and calculations performed to determine whether 
the system exceeded operating capacity during monitored recycle events 
and the number of event flow values that exceeded State approved 
operating capacity.
    (C) A plant schematic showing the origin of all recycle flows, the 
hydraulic conveyance used to transport them, and their final 
destination in the plant.
    (D) A list of all the recycle flows and the frequency at which they 
are returned to the plant's primary treatment process.
    (E) Average and maximum backwash flow rate through the filters and 
the average and maximum duration of the filter backwash process, in 
minutes.
    (F) Typical filter run length and a written summary of how filter 
run length is determined (preset run time, headloss, turbidity 
breakthrough, etc.).
    (ii) [Reserved]
    (4) All subpart H systems performing self assessments are required 
to modify their recycle practice in accordance with the State 
determination by [DATE 60 MONTHS AFTER DATE OF PUBLICATION OF FINAL 
RULE IN THE FEDERAL REGISTER] and keep a copy of the self assessment 
report submitted to the State on file for review during sanitary 
surveys.
    (d) Subpart H public water systems practicing direct filtration and 
recycling to the primary treatment process are required to submit data 
to the State on their current recycle treatment no later than [DATE 42 
MONTHS AFTER DATE OF PUBLICATION OF FINAL RULE IN THE FEDERAL 
REGISTER.]
    (1) Direct filtration systems submitting data to the State shall 
report the following information, at a minimum:
    (i) Data Submitted to States by Direct Filtration Systems:
    (A) A plant schematic showing the origin of all recycle flows, the 
hydraulic conveyance used to transport them, and their final 
destination in the plant.
    (B) The number of filters used at the plant to meet average daily 
production requirements and average and maximum backwash flow rate 
through the filter and the average and maximum duration of the filter 
backwash process, in minutes.
    (C) Whether recycle flow treatment or equalization is in place.
    (D) The type of treatment provided for the recycle flow.
    (E) For recycle equalization and treatment units: data on the 
physical dimensions of the unit (length, width (or circumference), 
depth,) sufficient to allow calculation of volume; typical and maximum 
hydraulic loading rate; type of treatment chemicals used and average 
dose and frequency of use, and frequency at which solids are removed 
from the unit, if applicable.
    (ii) [Reserved]
    (2) All direct filtration systems submitting data to the State are 
required to modify their recycle practice in accordance with the State 
determination no later than [DATE 60 MONTHS AFTER DATE OF PUBLICATION 
OF FINAL RULE IN THE FEDERAL REGISTER] and keep a copy of the report 
submitted to the State on file for review during sanitary surveys.
    9. Section 141.153 is amended by revising the first sentence of 
paragraph (d)(4)(v)(C) to read as follows:


Sec. 141.153  Content of the reports.

* * * * *
    (d) * * *
    (4) * * *
    (v) * * *
    (C) When it is reported pursuant to Sec. 141.73 or Sec. 141.173 or 
Sec. 141.551: the highest single measurement and the lowest monthly 
percentage of samples meeting the turbidity limits specified in 
Sec. 141.73 or Sec. 141.173, or Sec. 141.551 for the filtration 
technology being used. * * *
* * * * *
    10. The heading to Subpart P is revised as follows:

Subpart P--Enhanced Filtration and Disinfection-Systems Serving 
10,000 or More People

* * * * *

[[Page 19144]]

    11. Section 141.170 is amended by adding paragraph (d) to read as 
follows:


Sec. 141.170  General requirements.

* * * * *
    (d) Subpart H systems that did not conduct applicability monitoring 
under Sec. 141.172 because they served fewer than 10,000 persons when 
such monitoring was required but serve more than 10,000 persons prior 
to [DATE 36 MONTHS AFTER DATE OF PUBLICATION OF FINAL RULE IN THE 
FEDERAL REGISTER] must comply with Secs. 141.170, 141.171, 141.173, 
141.174, and 141.175. These systems must also consult with the State to 
establish a disinfection benchmark. A system that decides to make a 
significant change to its disinfection practice, as described in 
Sec. 141.172(c)(1)(i) through (iv) must consult with the State prior to 
making such change.
* * * * *
    12. Part 141 is amended by adding a new subpart T to read as 
follows:

Subpart T--Enhanced Filtration and Disinfection--Systems Serving 
Fewer than 10,000 People

Sec.

General Requirements

141.500   General requirements.
141.501   Who is subject to the requirements of subpart T?
141.502   When must my system comply with these requirements?
141.503   What does subpart T require?

Finished Water Reservoirs

141.510   Is my system subject to the new finished water reservoir 
requirements?
141.511   What is required of new finished water reservoirs?

Additional Watershed Control Requirements

141.520   Is my system subject to the updated watershed control 
requirements?
141.521   What updated watershed control requirements must my system 
comply with?
141.522   How does the State determine whether my system's watershed 
control requirements are adequate?

Disinfection Profile

141.530   Who must develop a Disinfection Profile and what is a 
Disinfection Profile?
141.531   How does my system demonstrate TTHM and HAA5 levels below 
0.064 mg/l and 0.048 mg/l respectively?
141.532   How does my system develop a Disinfection Profile and when 
must it begin?
141.533   What measurements must my system collect to calculate a 
Disinfection Profile?
141.534   How does my system use these measurements to calculate an 
inactivation ratio?
141.535   How does my system develop a Disinfection Profile if we 
use chloramines, ozone, or chlorine dioxide for primary 
disinfection?
141.536   If my system has developed an inactivation ratio; what 
must we do now?

Disinfection Benchmark

141.540   Who has to develop a Disinfection Benchmark?
141.541   What are significant changes to disinfection practice?
141.542   How is the Disinfection Benchmark calculated?
141.543   What if my system uses chloramines or ozone for primary 
disinfection?
141.544   What must my system do if considering a significant change 
to disinfection practices?

Combined Filter Effluent Requirements

141.550   Is my system required to meet subpart T combined filter 
effluent turbidity limits?
141.551   What strengthened combined filter effluent turbidity 
limits must my system meet?
141.552   If my system consists of ``alternative filtration'' and is 
required to conduct a demonstration, what is required of my system 
and how does the State establish my turbidity limits?
141.553   If my system practices lime softening, is there any 
special provision regarding my combined filter effluent?

Individual Filter Turbidity Requirements

141.560   Is my system subject to individual filter turbidity 
requirements?
141.561   What happens if my turbidity monitoring equipment fails?
141.562   What follow-up action is my system required to take based 
on turbidity monitoring of individual filters?
141.563   My system practices lime softening. Is there any special 
provision regarding my individual filter turbidity monitoring?

Reporting and Recordkeeping Requirements

142.570  What does subpart T require that my system report to the 
State?
142.571  What records does subpart T require my system to keep?
Subpart T--Enhanced Filtration and Disinfection--Systems Serving Fewer 
Than 10,000 People

General Requirements


Sec. 141.500  General requirements.

    The requirements of subpart T constitute national primary drinking 
water regulations. These regulations establish requirements for 
filtration and disinfection that are in addition to criteria under 
which filtration and disinfection are required under subpart H of this 
part. The regulations in this subpart establish or extend treatment 
technique requirements in lieu of maximum contaminant levels for the 
following contaminants: Giardia lamblia, viruses, heterotrophic plate 
count bacteria, Legionella, Cryptosporidium and turbidity. The 
treatment technique requirements consist of installing and properly 
operating water treatment processes which reliably achieve:
    (a) At least 99 percent (2 log) removal of Cryptosporidium between 
a point where the raw water is not subject to recontamination by 
surface water runoff and a point downstream before or at the first 
customer for filtered systems, or Cryptosporidium control under the 
watershed control plan for unfiltered systems.
    (b) Compliance with the profiling and benchmark requirements in 
Secs. 141.530 through 141.544.


Sec. 141.501  Who is subject to the requirements of subpart T?

    You are subject to these requirements if your system:
    (a) Is a public water system;
    (b) Uses surface water or GWUDI as a source; and
    (c) Serves fewer than 10,000 persons annually.


Sec. 141.502  When must my system comply with these requirements?

    You must comply with these requirements beginning [DATE 36 MONTHS 
AFTER DATE OF PUBLICATION OF FINAL RULE IN THE FEDERAL REGISTER] except 
where otherwise noted.


Sec. 141.503  What does subpart T require?

    There are six requirements of this subpart which your system may 
need to comply with. These requirements are discussed in detail later 
in this subpart. They are:
    (a) Any finished water reservoir for which construction begins on 
or after [DATE 60 DAYS AFTER DATE OF PUBLICATION OF FINAL RULE IN THE 
FEDERAL REGISTER] must be covered;
    (b) Unfiltered systems must comply with updated watershed control 
requirements;
    (c) All systems subject to the requirements of this subpart must 
develop a disinfection profile;
    (d) All systems subject to the requirements of this subpart that 
are considering a significant change to their disinfection practice 
must develop a disinfection benchmark and receive State approval before 
changing their disinfection practice;
    (e) Filtered systems must comply with specific combined filter 
effluent turbidity limits and monitoring and reporting requirements; 
and
    (f) Filtered systems using conventional or direct filtration must

[[Page 19145]]

comply with individual filter turbidity limits and monitoring and 
reporting requirements.

Finished Water Reservoirs


Sec. 141.510  Is my system subject to the new finished water reservoir 
requirements?

    All subpart H systems which serve populations fewer than 10,000 are 
subject to this requirement.


Sec. 141.511  What is required for new finished water reservoirs?

    If your system initiates construction of a finished water reservoir 
after [DATE 60 DAYS AFTER DATE OF PUBLICATION OF FINAL RULE IN THE 
FEDERAL REGISTER the reservoir must be covered. Finished water 
reservoirs constructed prior to [DATE 60 DAYS AFTER DATE OF PUBLICATION 
OF FINAL RULE IN THE FEDERAL REGISTER are not subject to this 
requirement.

Additional Watershed Control Requirements


Sec. 141.520  Is my system subject to the updated watershed control 
requirements?

    If you are a subpart H system serving fewer than 10,000 persons 
which does not provide filtration, you must continue to comply with all 
of the watershed control requirements in Sec. 141.71, as well as the 
additional watershed control requirements in Sec. 141.521.


Sec. 141.521  What additional watershed control requirements must my 
system comply with?

    Your system must also maintain the existing watershed control 
program to minimize the potential for contamination by Cryptosporidium 
oocysts in the source water. Your system's watershed control program 
must, for Cryptosporidium:
    (a) Identify watershed characteristics and activities which may 
have an adverse effect on source water quality; and
    (b) Monitor the occurrence of activities which may have an adverse 
effect on source water quality.


Sec. 141.522  How does the State determine whether my system's 
watershed control requirements are adequate?

    During an onsite inspection conducted under the provisions of 
Sec. 141.71(b)(3), the State must determine whether your watershed 
control program is adequate to limit potential contamination by 
Cryptosporidium oocysts. The adequacy of the program must be based on 
the comprehensiveness of the watershed review; the effectiveness of 
your program to monitor and control detrimental activities occurring in 
the watershed; and the extent to which your system has maximized land 
ownership and/or controlled land use within the watershed.

Disinfection Profile


Sec. 141.530  Who must develop a Disinfection Profile and what is a 
Disinfection Profile?

    All subpart H community and non-transient non-community water 
systems which serve fewer than 10,000 persons must develop a 
disinfection profile. A disinfection profile is a graphical 
representation of your system's level of Giardia lamblia or virus 
inactivation measured during the course of a year. Your system must 
develop a disinfection profile unless you can demonstrate to the State 
that your TTHM and HAA5 levels are less than 0.064 mg/l and 0.048 mg/l 
respectively, prior to January 7, 2003.


Sec. 141.531  How does my system demonstrate TTHM and HAA5 levels below 
0.064 mg/l and 0.048 mg/l respectively?

    In order to demonstrate that your TTHM and HAA5 levels are below 
0.064 mg/L and 0.048 mg/L, respectively your system must have collected 
one TTHM and one HAA5 sample taken between 1998-2002. Samples must have 
been collected during the month with the warmest water temperature, at 
the point of maximum residence time in your distribution system which 
indicate TTHM levels below 0.064 mg/l and HAA5 levels below 0.048 mg/L. 
By January 7, 2003, you must submit a copy of the results to the State 
along with a letter indicating your intention to forgo development of a 
disinfection profile because of the results of the sampling. This 
letter, along with a copy of your TTHM and HAA5 sample lab results must 
be kept on file for review by the State during a sanitary survey. If 
the data you have collected is either equal to or exceeds either 0.064 
mg/l for TTHM and/or 0.048 mg/l for HAA5s, you must develop a 
disinfection profile.


Sec. 141.532  How does my system develop a Disinfection Profile and 
when must it begin?

    A disinfection profile consists of three steps:
    (a) First, your system must collect measurements for several 
treatment parameters from the plant as discussed in Sec. 141.533. Your 
system must begin this monitoring no later than January 7, 2003.
    (b) Second, your system must use these measurements to calculate 
inactivation ratios as discussed in Secs. 141.534 and 141.535; and
    (c) Third, your system must use these inactivation ratios to 
develop a disinfection profile as discussed in Sec. 141.536.


Sec. 141.533  What measurements must my system collect to calculate a 
Disinfection Profile?

    Your system must monitor the parameters necessary to determine the 
total inactivation ratio using analytical methods in Sec. 141.74 (a), 
once per week on the same calendar day each week as follows:
    (a) The temperature of the disinfected water must be measured at 
each residual disinfectant concentration sampling point during peak 
hourly flow;
    (b) If the system uses chlorine, the pH of the disinfected water 
must be measured at each chlorine residual disinfectant concentration 
sampling point during peak hourly flow;
    (c) The disinfectant contact time(s) (``T'') must be determined 
during peak hourly flow; and
    (d) The residual disinfectant concentration(s) (``C'') of the water 
before or at the first customer and prior to each additional point of 
disinfection must be measured during peak hourly flow.


Sec. 141.534  How does my system use these measurements to calculate an 
inactivation ratio?

    Calculate the total inactivation ratio as follows, and multiply the 
value by 3.0 to determine log inactivation of Giardia lamblia:

------------------------------------------------------------------------
             If a system...                The system must determine...
------------------------------------------------------------------------
(a) Uses only one point of disinfectant  (1) One inactivation ratio
 application.                             (CTcalc/CT99.9) before or at
                                          the first customer during peak
                                          hourly flow, or

[[Page 19146]]

 
                                         (2) 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. Under this alternative,
                                          the system must calculate the
                                          total inactivation ratio by
                                          determining (CTcalc/CT99.9)
                                          for each sequence and then
                                          adding the (CTcalc/CT99.9)
                                          values together to determine
                                          ( (CTcalc/CT99.9)).
                                          You may use a spreadsheet that
                                          calculates CT and/or contains
                                          the necessary inactivation
                                          tables.
(b) Uses more than one point of          (1) The CTcalc/CT99.9 value of
 disinfectant application before the      each disinfection segment
 first customer.                          immediately prior to the next
                                          point of disinfectant
                                          application, or for the final
                                          segment, before or at the
                                          first customer, during peak
                                          hourly flow using the
                                          procedure described in the
                                          above paragraph.
------------------------------------------------------------------------

Sec. 141.535  How does my system develop a Disinfection Profile if we 
use chloramines, ozone, or chlorine dioxide for primary disinfection?

    If your system uses either chloramines, ozone or chlorine dioxide 
for primary disinfection, you must also calculate the logs of 
inactivation for viruses. You must develop an additional disinfection 
profile for viruses using a method approved by the State.


Sec. 141.536  If my system has developed an inactivation ratio, what 
must we do now?

    Each inactivation ratio serves as a data point in your disinfection 
profile. Your system will have obtained 52 measurements (one for every 
week of the year). This will allow your system and the State the 
opportunity to evaluate how microbial inactivation varied over the 
course of the year by looking at all 52 measurements (your Disinfection 
Profile). Your system must retain the Disinfection Profile data in 
graphic form, as a spreadsheet, or in some other format acceptable to 
the State for review as part of sanitary surveys conducted by the 
State. Your system will need to use this data to calculate a benchmark 
if considering changes to disinfection practices.

Disinfection Benchmark


Sec. 141.540  Who has to develop a Disinfection Benchmark?

    If you are a subpart H system required to develop a disinfection 
profile under Secs. 141.530 through 141.536, your system must develop a 
Disinfection Benchmark if you decide to make a significant change to 
disinfection practice. State approval must be obtained before you can 
implement a significant disinfection practice change.


Sec. 141.541  What are significant changes to disinfection practice?

    Significant changes to disinfection practice are:
    (a) Changes to the point of disinfection;
    (b) Changes to the disinfectant(s) used in the treatment plant;
    (c) Changes to the disinfection process; or
    (d) Any other modification identified by the State.


Sec. 141.542  How is the Disinfection Benchmark Calculated?

    If your system is making a significant change to its disinfection 
practice, it must calculate a disinfection benchmark using the 
following procedure:
    (a) To calculate a disinfection benchmark a system must perform the 
following steps:
    Step 1: Using the data your system collected to develop the 
Disinfection Profile, determine the average Giardia lamblia 
inactivation for each calender month by dividing the sum of all Giardia 
lamblia inactivations for that month by the number of values calculated 
for that month.
    Step 2: Determine the lowest monthly average value out of the 
twelve values. This value becomes the disinfection benchmark.
    (b) [Reserved]


Sec. 141.543  What if my system uses chloramines or ozone for primary 
disinfection?

    If your system uses chloramines, ozone or chlorinated dioxide for 
primary disinfection your system must calculate the disinfection 
benchmark from the data your system collected for viruses to develop 
the disinfection profile in addition to the Giardia lamblia 
disinfection benchmark calculated under Sec. 141.542. The disinfection 
benchmark must be calculated as described in Sec. 141.542.


Sec. 141.544  What must my system do if considering a significant 
change to disinfection practices?

    If your system is considering a significant change to the 
disinfection practice, it must complete a disinfection benchmark(s) as 
described in Secs. 141.542 and 141.543 and provide the benchmark(s) to 
your State. Your system may only make a significant disinfection 
practice change after receiving State approval. The following 
information must be submitted to the State as part of their review and 
approval process:
    (a) A description of the proposed change;
    (b) The disinfection profile for Giardia lamblia (and, if 
necessary, viruses) and disinfection benchmark;
    (c) An analysis of how the proposed change will affect the current 
levels of disinfection; and
    (d) Additional information requested by the State.

Combined Filter Effluent Requirements


Sec. 141.550  Is my system required to meet subpart T combined filter 
effluent turbidity limits?

    All subpart H systems which serve populations fewer than 10,000, 
and are required to filter, must meet combined filter effluent 
requirements. Unless your system consists of slow sand or diatomaceous 
earth filtration, you are required to meet the combined filter effluent 
turbidity limits in Sec. 141.551. If your system uses slow sand or 
diatomaceous earth filtration you must continue to meet the combined 
filter effluent turbidity limits in Sec. 141.73.


Sec. 141.551  What strengthened combined filter effluent turbidity 
limits must my system meet?

    Your system must meet two strengthened combined filter effluent 
turbidity limits.
    (a) The first combined filter effluent turbidity limit is a ``95th 
percentile'' turbidity limit which your system must meet in at least 95 
percent of the turbidity measurements taken each month. Measurements 
must continue to be taken as described in Sec. 141.74(a) and (c). The 
following table describes the required limits for specific filtration 
technologies.

[[Page 19147]]



------------------------------------------------------------------------
                                          Your 95th percentile turbidity
    If your system consists of . . .              value is . . .
------------------------------------------------------------------------
(1) Conventional filtration or direct    0.3 NTU.
 filtration.
(2) Membrane filtration................  0.3 NTU or a value determined
                                          by the State (not to exceed 1
                                          NTU) based on a demonstration
                                          conducted by the system as
                                          described in Sec.  141.552.
(3) All other ``alternative''            A value determined by the State
 filtration.                              (not to exceed 1 NTU) based on
                                          the demonstration described in
                                          Sec.  141.552.
------------------------------------------------------------------------

    (b) The second combined filter effluent turbidity limit is a 
``maximum'' turbidity limit which your system may at no time exceed 
during the month. Measurements must continue to be taken as described 
in Sec. 141.74(a) and (c). The following table describes the required 
limits for specific filtration technologies.

------------------------------------------------------------------------
                                         Your maximum turbidity value is
    If your system consists of . . .                  . . .
------------------------------------------------------------------------
(1) Conventional filtration or direct    1 NTU.
 filtration.
(2) Membrane filtration................  1 NTU or a value determined by
                                          the State (not to exceed 5
                                          NTU) based on a demonstration
                                          conducted by the system as
                                          described in Sec.  141.552.
(3) All other ``alternative''            A value determined by the State
 filtration.                              (not to exceed 5 NTU) based on
                                          the demonstration as described
                                          in Sec.  141.552.
------------------------------------------------------------------------

Sec. 141.552  If my system consists of ``alternative filtration'' and 
is required to conduct a demonstration, What is required of my system 
and how does the State establish my turbidity limits?

    (a) If your system is required to conduct a demonstration (see 
tables in Sec. 141.551), your system must demonstrate to the State, 
using pilot plant studies or other means, that your system's 
filtration, in combination with disinfection treatment, consistently 
achieves:
    (1) 99.9 percent removal and/or inactivation of Giardia lamblia 
cysts;
    (2) 99.99 percent removal and/or inactivation of viruses; and
    (3) 99 percent removal of Cryptosporidium oocysts.
    (b) If the State approves your demonstration, it will set turbidity 
performance requirements that your system must meet:
    (1) At least 95 percent of the time (not to exceed 1 NTU); and
    (2) That your system must not exceed at any time (not to exceed 5 
NTU).


Sec. 141.553  If my system practices lime softening, is there any 
special provision regarding my combined filter effluent?

    If your system practices lime softening, you may acidify 
representative combined filter effluent turbidity samples prior to 
analysis using a protocol approved by the State.

Individual Filter Turbidity Requirements


Sec. 141.560  Is my system subject to individual filter turbidity 
requirements?

    If your system is a subpart H system serving fewer than 10,000 
people and utilizing conventional filtration or direct filtration, you 
must conduct continuous monitoring of turbidity for each individual 
filter at your system. The following requirements apply to individual 
filter turbidity monitoring:
    (a) Monitoring must be conducted using an approved method in 
Sec. 141.74(a);
    (b) Calibration of turbidimeters must be conducted using procedures 
specified by the manufacturer;
    (c) Results of individual filter turbidity monitoring must be 
recorded every 15 minutes;
    (d) Monthly reporting must be completed according Sec. 141.570; and
    (e) Records must be maintained according to Sec. 141.571.


Sec. 141.561  What happens if my system's turbidity monitoring 
equipment fails?

    If there is a failure in the continuous turbidity monitoring 
equipment, the system must conduct grab sampling every four hours in 
lieu of continuous monitoring until the turbidimeter is back on-line. A 
system has five working days to resume continuous monitoring before a 
violation is incurred.


Sec. 141.562  What follow-up action is my system required to take based 
on turbidity monitoring of individual filters?

    Follow-up action is required according to the following tables:

------------------------------------------------------------------------
   If the turbidity of an individual
           filter exceeds...                    The system must...
------------------------------------------------------------------------
(a) If the turbidity of an individual    Submit an exceptions report to
 filter exceeds 1.0 NTU (in two           the State by the 10th of the
 consecutive recordings).                 month which includes the
                                          filter number(s),
                                          corresponding date(s), and the
                                          turbidity value(s) which
                                          exceeded 1.0 NTU.
------------------------------------------------------------------------


------------------------------------------------------------------------
  If an exceptions report is submitted
         for the same filter...                 The system must...
------------------------------------------------------------------------
(b) If an exceptions report is           Conduct a self-assessment of
 submitted for the same filter three      the filter within 14 days of
 months in a row.                         the exceedance and report that
                                          the self assessment was
                                          conducted by the 10th of the
                                          following month. The self
                                          assessment must consist of at
                                          least the following
                                          components: Assessment of
                                          filter performance;
                                          development of a filter
                                          profile; identification and
                                          prioritization of factors
                                          limiting filter performance;
                                          assessment of the
                                          applicability of corrections;
                                          and preparation of a filter
                                          self-assessment report.

[[Page 19148]]

 
(c) If an exceptions report is           (1) Arrange to have a
 submitted for the same filter two        comprehensive performance
 months in a row and both months          evaluation (CPE) conducted by
 contain exceedances of 2.0 NTU (in 2     the State or a third party
 consecutive recordings).                 approved by the State no later
                                          than 30 days following the
                                          exceedance and have the
                                          evaluation completed and
                                          submitted to the State no
                                          later than 90 days following
                                          the exceedance, Unless--
                                         (2) A CPE has been completed by
                                          the State or a third party
                                          approved by the State within
                                          the 12 prior months or the
                                          system and State are jointly
                                          participating in an ongoing
                                          Comprehensive Technical
                                          Assistance (CTA) project at
                                          the system.
------------------------------------------------------------------------

Sec. 141.563  My system practices lime softening. Is there any special 
provision regarding my individual filter turbidity monitoring?

    If your system utilizes lime softening, you may apply to the State 
for alternative turbidity exceedance levels for the levels specified in 
the table in Sec. 141.562. You must be able to demonstrate to the State 
that higher turbidity levels in individual filters are due to lime 
carryover only, and not due to degraded filter performance.

Reporting and Recordkeeping Requirements


Sec. 141.570  What does subpart T require that my system report to the 
State?

    This subpart T requires your system to report several items to the 
State. The following table describes the items which must be reported 
and the frequency of reporting. Your system is required to report the 
information described below, if it is subject to the specific 
requirement shown in the first column.

----------------------------------------------------------------------------------------------------------------
        Corresponding requirement            Description of information to report              Frequency
----------------------------------------------------------------------------------------------------------------
(a) Combined Filter Effluent              (1)The total number of filtered water       By the 10th of the
 Requirements.                             turbidity measurements taken during the     following month.
                                           month.
                                         -----------------------------------------------------------------------
                                          (2) The number and percentage of filtered   By the 10th of the
                                           water turbidity measurements taken during   following month.
                                           the month which are greater than your
                                           system's required 95th percentile limit.
                                         -----------------------------------------------------------------------
                                          (3) The date and value of any turbidity     (i) Within 24 hours of
                                           measurements taken during the month which   exceedance and
                                           exceed the maximum turbidity value for
                                           your filtration system.
                                                                                      (ii) By the 10th of the
                                                                                       following month.
                                         -----------------------------------------------------------------------
(b) Individual Filter Turbidity           (1) That your system conducted individual   By the 10th of the
 Requirements.                             filter turbidity monitoring during the      following month.
                                           month.
                                         -----------------------------------------------------------------------
                                          (2) The filter number(s), corresponding     By the 10th of the
                                           date(s), and the turbidity value(s) which   following month only if--
                                           exceeded 1.0 NTU during the month..
                                                                                      (ii) 2 consecutive values
                                                                                       exceeded 1.0 NTU.
                                         -----------------------------------------------------------------------
                                          (3) That a self assessment was conducted    (i) By the 10th of the
                                           within 14 days of the date it was           following month (or 14
                                           triggered.                                  days after the self
                                                                                       assessment was triggered
                                                                                       only if the self
                                                                                       assessment was triggered
                                                                                       during the last four days
                                                                                       of the month) only if--
                                                                                      (ii) A self-assessment is
                                                                                       required.
                                         -----------------------------------------------------------------------
                                          (4) That a CPE is required and the date     (i) By the 10th of the
                                           that it was triggered.                      following month only if--
                                                                                      (ii) A CPE is required.
                                         -----------------------------------------------------------------------
                                          (5) Copy of completed CPE report..........  Within 90 days after the
                                                                                       CPE was triggered.
                                         -----------------------------------------------------------------------
(c) Disinfection Profiling..............  (1) Results of applicability monitoring     No later than January 7,
                                           which show TTHM levels 0.064 mg/l and       2003.
                                           HAA5 levels 0.048 mg/l. (Only if your
                                           system wishes to forgo profiling) or that
                                           your system has begun disinfection
                                           profiling.
                                         -----------------------------------------------------------------------
(d) Disinfection Benchmarking...........  (1) A description of the proposed change    Anytime your system is
                                           in disinfection, your system's              considering a significant
                                           disinfection profile for Giardia lamblia    change to its
                                           (and, if necessary, viruses) and            disinfection practice.
                                           disinfection benchmark, and an analysis
                                           of how the proposed change will affect
                                           the current levels of disinfection.
----------------------------------------------------------------------------------------------------------------


[[Page 19149]]

Sec. 141.571  What records does subpart T require my system to keep?

    Your system must keep several types of records based on the 
requirements of subpart T. The following table describes the necessary 
records, the length of time these records must be kept, and for which 
requirement the records pertain. Your system is required to maintain 
records described in this table, if it is subject to the specific 
requirement shown in the first column. For example, if your system uses 
slow sand filtration, you would not be required to keep individual 
filter turbidity records:

----------------------------------------------------------------------------------------------------------------
                                                                                       Duration of time records
        Corresponding requirement              Description of necessary records              must be kept
----------------------------------------------------------------------------------------------------------------
(a) Individual Filter Turbidity           Results of individual filter monitoring...  At least 3 years.
 Requirements.
                                         -----------------------------------------------------------------------
(b) Disinfection Profiling..............  Results of Profile (including raw data and  Indefinitely.
                                           analysis).
                                         -----------------------------------------------------------------------
(c) Disinfection Benchmarking...........  Benchmark (including raw data and           Indefinitely.
                                           analysis).
                                         -----------------------------------------------------------------------
(d) Covered Reservoirs..................  Date of construction for all uncovered      Indefinitely.
                                           finished water reservoirs utilized by
                                           your system.
----------------------------------------------------------------------------------------------------------------

PART 142--NATIONAL PRIMARY DRINKING WATER REGULATIONS IMPLEMENTATION
    13. The authority citation for Part 142 continues to read as 
follows:

    Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4, 300j-9, and 300j-11.

    14. Section 142.14 is amended by revising paragraphs (a)(3), 
(a)(4)(i), (a)(4)(ii) introductory text, and (a)(7) to read as follows:


Sec. 142.14  Records kept by States.

    (a)* * *
    (3) Records of turbidity measurements must be kept for not less 
than one year. The information retained must be set forth in a form 
which makes possible comparison with the limits specified in 
Secs. 141.71, 141.73, 141.173 and 141.175, 141.550-141.553 and 141.560-
141.563 of this chapter. Until June 29, 1993, for any public water 
system which is providing filtration treatment and until December 30, 
1991, for any public water system not providing filtration treatment 
and not required by the State to provide filtration treatment, records 
kept must be set forth in a form which makes possible comparison with 
the limits contained in Sec. 141.13 of this chapter.
* * * * *
    (4)(i) Records of disinfectant residual measurements and other 
parameters necessary to document disinfection effectiveness in 
accordance with Secs. 141.72 and 141.74 of this chapter and the 
reporting requirements of Secs. 141.75, 141.175, and 141.570, of this 
chapter must be kept for not less than one year.
    (ii) Records of decisions made on a system-by-system and case-by-
case basis under provisions of part 141, subpart H, subpart P, or 
subpart T of this chapter, must be made in writing and kept at the 
State.
* * * * *
    (7) Any decisions made pursuant to the provisions of part 141, 
subpart P or subpart T of this chapter.
    (i) Records of systems consulting with the State concerning a 
modification to disinfection practice under Secs. 141.172(c), 
141.170(d), and 141.544 of this chapter, including the status of the 
consultation or approval.
    (ii) Records of decisions that a system using alternative 
filtration technologies, as allowed under Secs. 141.173(b) and 
Sec. 141.552 of this chapter, can consistently achieve a 99.9 percent 
removal and/or inactivation of Giardia lamblia cysts, 99.99 percent 
removal and/or inactivation of viruses, and 99 percent removal of 
Cryptosporidium oocysts. The decisions must include State-set 
enforceable turbidity limits for each system. A copy of the decision 
must be kept until the decision is reversed or revised. The State must 
provide a copy of the decision to the system.
    (iii) Records of systems required to do filter self-assessment, 
CPE, or CCP under the requirements of Sec. 141.175 and Sec. 141.562 of 
this chapter.
* * * * *
    15. Section 142.15 is amended by adding paragraphs (c)(6) and 
(c)(7) and (c)(8).


Sec. 142.15  Reports by States.

* * * * *
    (c) * * *
    (6) Recycle return location. A list of all systems moving the 
recycle return location prior to the point of primary coagulant 
addition. The list must also contain all the systems the State granted 
alternate recycle locations, describe the alternative recycle return 
location, and briefly discuss the reason(s) the alternate recycle 
location was granted and is due [DATE 60 MONTHS AFTER DATE OF 
PUBLICATION OF FINAL RULE IN THE FEDERAL REGISTER].
    (7) Self assessment determination. A list of all systems performing 
self assessments must be reported to EPA. The list must state whether 
individual plants exceeded State approved operating capacity during 
self assessment monitoring and whether the State required modification 
to recycle practice. A brief description of the modification to recycle 
practice required at each plant must be provided. If a plant exceeded 
State approved operating capacity, and the State did not require 
modification of recycle practice, the State must provide a brief 
explanation for this decision. Self assessment results must be reported 
no later than [DATE 54 MONTHS AFTER DATE OF PUBLICATION OF FINAL RULE 
IN THE FEDERAL REGISTER].
    (8) Direct filtration determination. A list of all direct 
filtration systems recycling within the treatment process must be 
submitted to EPA. The list must state which systems were required to 
modify recycle practice and briefly describe the modification and the 
reason it was required. It must also identify systems not required to 
modify recycle practice and provide a brief description of the reason 
modification to recycle practice was not required. The list must be 
submitted no later than [DATE 54 MONTHS AFTER DATE OF PUBLICATION OF 
FINAL RULE IN THE FEDERAL REGISTER].
* * * * *
    16. Section 142.16 is amended by adding paragraph (b)(2)(v), 
(b)(2)(vi), and (b)(2)(vii) and (i) to read as follows:


Sec. 142.16  Special primacy requirements.

* * * * *
    (b) * * *
    (2) * * *
    (v) The application must describe the criteria the State will use 
to determine alternate recycle locations for public water systems 
applying to return spent filter backwash, thickener supernatant,

[[Page 19150]]

or liquids from dewatering to an alternate location other than prior to 
the point of primary coagulant addition.
    (vi) The application must describe the criteria the State will use 
to determine whether public water systems completing self assessments 
are required to modify recycle practice and the criteria that will be 
used to specify modifications to recycle practice.
    (vii) The application must describe the criteria the State will use 
to determine whether direct filtration systems are required to change 
recycle practice and the criteria that will be used to specify changes 
to recycle practice.
* * * * *
    (i) Requirements for States to adopt 40 CFR part 141, subpart T 
Enhanced Filtration and Disinfection. In addition to the general 
primacy requirements enumerated elsewhere in this part, including the 
requirement that State provisions are no less stringent than the 
federal requirements, an application for approval of a State program 
revision that adopts 40 CFR part 141, subpart T Enhanced Filtration and 
Disinfection, must contain the information specified in this paragraph:
    (1) Enforceable requirements. States must have rules or other 
authority to require systems to participate in a Comprehensive 
Technical Assistance (CTA) activity, the performance improvement phase 
of the Composite Correction Program (CCP). The State shall determine 
whether a CTA must be conducted based on results of a CPE which 
indicate the potential for improved performance, and a finding by the 
State that the system is able to receive and implement technical 
assistance provided through the CTA. A CPE is a thorough review and 
analysis of a system's performance-based capabilities and associated 
administrative, operation and maintenance practices. It is conducted to 
identify factors that may be adversely impacting a plant's capability 
to achieve compliance. During the CTA phase, the system must identify 
and systematically address factors limiting performance. The CTA is a 
combination of utilizing CPE results as a basis for follow-up, 
implementing process control priority-setting techniques and 
maintaining long-term involvement to systematically train staff and 
administrators.
    (2) State practices or procedures. (i) Section 141.536 of this 
chapter--How the State will approve a method to calculate the logs of 
inactivation for viruses for a system that uses either chloramines or 
ozone for primary disinfection.
    (ii) Section 141.544 of this chapter--How the State will approve 
modifications to disinfection practice.
    (iii) Section 141.552 of this chapter--For filtration technologies 
other than conventional filtration treatment, direct filtration, slow 
sand filtration, diatomaceous earth filtration, or membrane filtration, 
how the State will determine that a public water system may use a 
filtration technology if the PWS demonstrates to the State, using pilot 
plant studies or other means, that the alternative filtration 
technology (or membrane filtration), in combination with disinfection 
treatment that meets the requirements of Sec. 141.72(b) of this 
chapter, consistently achieves 99.9 percent removal and/or inactivation 
of Giardia lamblia cysts and 99.99 percent removal and/or inactivation 
of viruses, and 99 percent removal of Cryptosporidium oocysts. For a 
system that makes this demonstration, how the State will set turbidity 
performance requirements that the system must meet 95 percent of the 
time and that the system may not exceed at any time at a level that 
consistently achieves 99.9 percent removal and/or inactivation of 
Giardia lamblia cysts, 99.99 percent removal and/or inactivation of 
viruses, and 99 percent removal of Cryptosporidium oocysts.
[FR Doc. 00-8155 Filed 4-7-00; 8:45 am]
BILLING CODE 6560-50-P